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principles_of_accounting,_volume_1:_financial_accounting
Summary 9.1 Explain the Revenue Recognition Principle and How It Relates to Current and Future Sales and Purchase Transactions According to the revenue recognition principle, a company will recognize revenue when a product or service is provided to a client. The revenue must be reported in the period when the earnings process completes. According to the matching principle, expenses must be matched with revenues in the period in which they are incurred. A mismatch in revenues and expenses can lead to financial statement misreporting. When a customer pays for a product or service on a line of credit, the Accounts Receivable account is used. Accounts receivable must satisfy the following criteria: the customer owes money and has yet to pay, the amount is due in less than a company’s operating cycle, and the account usually does not incur interest. When a customer purchases a product or service on credit, using an in-house account, Accounts Receivable increases and Sales Revenue increases. When the customer pays the amount due, Accounts Receivable decreases and Cash increases. When a customer purchases a product or service with a third-party credit card, such as Visa , Accounts Receivable increases, Credit Card Expense increases, and Sales Revenue increases. When the credit card company pays the amount due, Accounts Receivable decreases and Cash increases for the original sales price less the credit card usage fee. 9.2 Account for Uncollectible Accounts Using the Balance Sheet and Income Statement Approaches Bad debt is a result of unpaid and uncollectible customer accounts. Companies are required to record bad debt on financial statements as expenses. The direct write-off method records bad debt only when the due date has passed for a known amount. Bad Debt Expense increases (debit) and Accounts Receivable decreases (credit) for the amount uncollectible. The allowance method estimates uncollectible bad debt and matches the expense in the current period to revenues generated. There are three ways to calculate this estimation: the income statement method, balance sheet method/percentage of receivables, and balance sheet aging of receivables method. The income statement method estimates bad debt based on a percentage of credit sales. Bad Debt Expense increases (debit) and Allowance for Doubtful Accounts increases (credit) for the amount estimated as uncollectible. The balance sheet method estimates bad debt based on a percentage of outstanding accounts receivable. Bad Debt Expense increases (debit) and Allowance for Doubtful Accounts increases (credit) for the amount estimated as uncollectible. The balance sheet aging of receivables method estimates bad debt based on outstanding accounts receivable, but it considers the time period that an account is past due. Bad Debt Expense increases (debit) and Allowance for Doubtful Accounts increases (credit) for the amount estimated as uncollectible. 9.3 Determine the Efficiency of Receivables Management Using Financial Ratios Receivable ratios are best used to determine quick debt collection and lending practices. An investor, lender, or management may use these ratios—in conjunction with financial statement review, past performance, industry standards, and trends—to make an informed financial decision. The accounts receivable turnover ratio shows how many times receivables are collected during a period and converted to cash. The ratio is found by taking net credit sales and dividing by average accounts receivable for the period. The number of days’ sales in receivables ratio shows the expected number of days it will take to convert accounts receivable into cash. The ratio is found by taking 365 days and dividing by the accounts receivable turnover ratio. 9.4 Discuss the Role of Accounting for Receivables in Earnings Management Companies may look to report earnings differently to improve stakeholder’s views of financial position. Earnings management works within GAAP to accomplish this, while earnings manipulation ignores GAAP. Companies may choose to manage earnings to improve income level, increase borrowing opportunities, decrease tax liabilities, and improve company valuation for sales transactions. Accounts receivable is often prey to earnings manipulations. Earnings management can occur in several ways, including changes to bad debt estimation methods, percentage uncollectible figures, and category distribution within the balance sheet aging method. To understand company performance and unveil any management or manipulation to earnings, ratio analysis is paramount. Number of days’ sales in receivables ratio, and trend analysis, are most commonly used. 9.5 Apply Revenue Recognition Principles to Long-Term Projects Long-term construction projects may recognize revenue under the percentage of completion method or the completed contract method. The percentage of completion method distributes cost and revenues based on the amount of estimated contract completion during the period. Real estate installment sales require periodic payment from buyers. The installment method takes into account risk and distributes revenue based on a percentage of gross profit realized each period. With multi-year magazine subscriptions, customers pay in advance for subscription services, and the amount reported for revenue each period is reasonably estimated, until any disruption to the contract occurs. At that time, a new estimation will be distributed over the life of the subscription. In a combined equipment purchase with accompanying service contract, the customer pays for the contract up front, but there is no guarantee that service will be provided. Thus, a company may distribute estimated service revenues over the life of the contract or defer recognition and associated expenses until the contract period is complete. 9.6 Explain How Notes Receivable and Accounts Receivable Differ Accounts receivable is an informal agreement between customer and company, with collection occurring in less than a year, and no interest requirement. In contrast, notes receivable is a legal contract, with collection occurring typically over a year, and interest requirements. The terms of a note contract establish the principal collection amount, maturity date, and annual interest rate. Interest is computed as the principal amount multiplied by the part of the year, multiplied by the annual interest rate. The entry to record accumulated interest increases interest receivable and interest revenue. An honored note means collection occurred on time and in full. Recording an honored note includes an increase to cash and interest revenue, and a decrease to interest receivable and notes receivable. A dishonored note means collection did not occur on time or in full. In this case, a note and the accumulated interest would be converted to accounts receivable. When a company cannot collect on account, the company may consider selling the receivable to a collection agency. They will sell the receivable at a fraction of the value in order to apply resources elsewhere. If a customer cannot pay its accounts receivable on time, it may renegotiate terms that include a note and interest, thereby converting the accounts receivable to notes receivable. in this case, accounts receivable decreases, and notes receivable and cash increase.
Chapter Outline 9.1 Explain the Revenue Recognition Principle and How It Relates to Current and Future Sales and Purchase Transactions 9.2 Account for Uncollectible Accounts Using the Balance Sheet and Income Statement Approaches 9.3 Determine the Efficiency of Receivables Management Using Financial Ratios 9.4 Discuss the Role of Accounting for Receivables in Earnings Management 9.5 Apply Revenue Recognition Principles to Long-Term Projects 9.6 Explain How Notes Receivable and Accounts Receivable Differ 9.7 Appendix: Comprehensive Example of Bad Debt Estimation Why It Matters Marie owns Skateboards Unlimited, a skateboard lifestyle shop offering a variety of skate-specific clothing, equipment, and accessories. Marie prides herself on her ability to accommodate customer needs. One way she accomplishes this goal is by extending to the customer a line of credit, which would create an account receivable for Skateboards Unlimited. Even though she has yet to collect cash from her credit customers, she recognizes the revenue as earned when the sale occurs. This is important, as it allows her to match her sales correctly with sales-associated expenses in the proper period, based on the matching principle and revenue recognition guidelines. By offering credit terms, Skateboards Unlimited operates in good faith that customers will pay their accounts in full. Sometimes this does not occur, and the bad debt from the receivable has to be written off. Marie typically estimates this write-off amount, to show potential investors and lenders a consistent financial position. When writing off bad debt, Marie is guided by specific accounting principles that dictate the estimation and bad debt processes. Skateboards Unlimited will need to carefully manage its receivables and bad debt to reach budget projections and grow the business. This chapter explains and demonstrates demonstrate the two major methods of estimating and recording bad debt expenses that Skateboards Unlimited can apply under generally accepted accounting principles (GAAP).
[ { "answer": { "ans_choice": 2, "ans_text": "C" }, "bloom": null, "hl_context": "<hl> The revenue recognition principle , which states that companies must recognize revenue in the period in which it is earned , instructs companies to recognize revenue when a four-step process is completed . <hl> <hl> This may not necessarily be when cash is collected . <hl> Revenue can be recognized when all of the following criteria have been met : Revenue and expense recognition timing is critical to transparent financial presentation . GAAP governs recognition for publicly traded companies . Even though GAAP is required only for public companies , to display their financial position most accurately , private companies should manage their financial accounting using its rules . <hl> Two principles governed by GAAP are the revenue recognition principle and the matching principle . <hl> Both the revenue recognition principle and the matching principle give specific direction on revenue and expense reporting .", "hl_sentences": "The revenue recognition principle , which states that companies must recognize revenue in the period in which it is earned , instructs companies to recognize revenue when a four-step process is completed . This may not necessarily be when cash is collected . Two principles governed by GAAP are the revenue recognition principle and the matching principle .", "question": { "cloze_format": "___ is not a criterion to recognize revenue under GAAP.", "normal_format": "Which of the following is not a criterion to recognize revenue under GAAP?", "question_choices": [ "The earnings process must be completed.", "A product or service must be provided.", "Cash must be collected.", "GAAP requires that the accrual basis accounting principle be used in the revenue recognition process." ], "question_id": "fs-idm225158240", "question_text": "Which of the following is not a criterion to recognize revenue under GAAP?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 2, "ans_text": "Revenue and expenses are matched based on when expenses are paid." }, "bloom": null, "hl_context": "<hl> Accrual accounting also incorporates the matching principle ( otherwise known as the expense recognition principle ) , which instructs companies to record expenses related to revenue generation in the period in which they are incurred . <hl> The principle also requires that any expense not directly related to revenues be reported in an appropriate manner . For example , assume that a company paid $ 6,000 in annual real estate taxes . The principle has determined that costs cannot effectively be allocated based on an individual month ’ s sales ; instead , it treats the expense as a period cost . In this case , it is going to record 1/12 of the annual expense as a monthly period cost . Overall , the “ matching ” of expenses to revenues projects a more accurate representation of company financials . When this matching is not possible , then the expenses will be treated as period costs .", "hl_sentences": "Accrual accounting also incorporates the matching principle ( otherwise known as the expense recognition principle ) , which instructs companies to record expenses related to revenue generation in the period in which they are incurred .", "question": { "cloze_format": "The matching principle criteria is best represented as ___ .", "normal_format": "Which of the following best represents the matching principle criteria?", "question_choices": [ "Expenses are reported in the period in which they were incurred.", "Expenses may be reported in a different period than the matching revenues.", "Revenue and expenses are matched based on when expenses are paid.", "Revenue is recognized when an order occurs and not when the actual sale is initiated." ], "question_id": "fs-idm210789664", "question_text": "Which of the following best represents the matching principle criteria?" }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 1, "ans_text": "B" }, "bloom": null, "hl_context": "<hl> Accounts Receivable : Visa increases ( debit ) for the sale amount ( $ 300 ) less the credit card fee ( $ 15 ) , for a $ 285 Accounts Receivable balance due from Visa . <hl> <hl> BWW ’ s Credit Card Expense increases ( debit ) for the amount of the credit card fee ( $ 15 ; 300 × 5 % ) , and Sales Revenue increases ( credit ) for the original sales amount ( $ 300 ) . <hl> BWW recognizes revenue as earned for this transaction because it provided the canoe and completed the earnings process . Cost of Goods Sold increases ( debit ) and Merchandise Inventory decreases ( credit ) for $ 150 , the expense associated with the sale . As with the previous example , by recording both a sale and cost entry , the matching principle requirement is met . When Visa pays the amount owed to BWW , the following entry occurs in BWW ’ s records . <hl> Another credit transaction that requires recognition is when a customer pays with a credit card ( Visa and MasterCard , for example ) . <hl> This is different from credit extended directly to the customer from the company . In this case , the third-party credit card company accepts the payment responsibility . This reduces the risk of nonpayment , increases opportunities for sales , and expedites payment on accounts receivable . The tradeoff for the company receiving these benefits from the credit card company is that a fee is charged to use this service . The fee can be a flat figure per transaction , or it can be a percentage of the sales price . Using BWW as the example , let ’ s say one of its customers purchased a canoe for $ 300 , using his or her Visa credit card . The cost to BWW for the canoe is $ 150 . Visa charges BWW a service fee equal to 5 % of the sales price . <hl> At the time of sale , the following journal entries are recorded . <hl>", "hl_sentences": "Accounts Receivable : Visa increases ( debit ) for the sale amount ( $ 300 ) less the credit card fee ( $ 15 ) , for a $ 285 Accounts Receivable balance due from Visa . BWW ’ s Credit Card Expense increases ( debit ) for the amount of the credit card fee ( $ 15 ; 300 × 5 % ) , and Sales Revenue increases ( credit ) for the original sales amount ( $ 300 ) . Another credit transaction that requires recognition is when a customer pays with a credit card ( Visa and MasterCard , for example ) . At the time of sale , the following journal entries are recorded .", "question": { "cloze_format": "If a customer pays with a credit card and the service has been provided, the accounts that will be used to record the sales entry for this transaction are ___ .", "normal_format": "If a customer pays with a credit card and the service has been provided, which of the following accounts will be used to record the sales entry for this transaction?", "question_choices": [ "Cost of Goods Sold, Merchandise Inventory, Sales Revenue", "Sales Revenue, Credit Card Expense, Accounts Receivable", "Accounts Receivable, Merchandise Inventory, Credit Card Expense", "Cost of Goods Sold, Credit Card Expense, Sales Revenue" ], "question_id": "fs-idm203131264", "question_text": "If a customer pays with a credit card and the service has been provided, which of the following accounts will be used to record the sales entry for this transaction?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 2, "ans_text": "C" }, "bloom": null, "hl_context": "<hl> The direct write-off method delays recognition of bad debt until the specific customer accounts receivable is identified . <hl> Once this account is identified as uncollectible , the company will record a reduction to the customer ’ s accounts receivable and an increase to bad debt expense for the exact amount uncollectible .", "hl_sentences": "The direct write-off method delays recognition of bad debt until the specific customer accounts receivable is identified .", "question": { "cloze_format": "The method that delays recognition of bad debt until the specific customer accounts receivable is identified is the ___.", "normal_format": "Which method delays recognition of bad debt until the specific customer accounts receivable is identified?", "question_choices": [ "income statement method", "balance sheet method", "direct write-off method", "allowance method" ], "question_id": "fs-idm352226176", "question_text": "Which method delays recognition of bad debt until the specific customer accounts receivable is identified?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 3, "ans_text": "balance sheet aging of receivables method" }, "bloom": null, "hl_context": "<hl> The balance sheet aging of receivables method estimates bad debt expenses based on the balance in accounts receivable , but it also considers the uncollectible time period for each account . <hl> <hl> The longer the time passes with a receivable unpaid , the lower the probability that it will get collected . <hl> An account that is 90 days overdue is more likely to be unpaid than an account that is 30 days past due .", "hl_sentences": "The balance sheet aging of receivables method estimates bad debt expenses based on the balance in accounts receivable , but it also considers the uncollectible time period for each account . The longer the time passes with a receivable unpaid , the lower the probability that it will get collected .", "question": { "cloze_format": "The estimation method that considers the amount of time past due when computing bad debt is the ___ .", "normal_format": "Which of the following estimation methods considers the amount of time past due when computing bad debt?", "question_choices": [ "balance sheet method", "direct write-off method", "income statement method", "balance sheet aging of receivables method" ], "question_id": "fs-idm351395568", "question_text": "Which of the following estimation methods considers the amount of time past due when computing bad debt?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 0, "ans_text": "A" }, "bloom": null, "hl_context": "The ratio for 2017 is 73 days ( 365/5 ) , and for 2018 is 71.01 days ( 365/5 . 14 ) , rounded . <hl> This means it takes 73 days in 2017 and 71.01 days in 2018 to complete the collection cycle , which is a decrease from 2017 to 2018 . <hl> <hl> A downward trend is a positive for the company , and BWW outperforms the competition slightly . <hl> <hl> This is good because BWW can use the cash toward other business expenditures , or the downward trend could signal that the company needs to loosen credit terms or more aggressively collect outstanding accounts . <hl>", "hl_sentences": "This means it takes 73 days in 2017 and 71.01 days in 2018 to complete the collection cycle , which is a decrease from 2017 to 2018 . A downward trend is a positive for the company , and BWW outperforms the competition slightly . This is good because BWW can use the cash toward other business expenditures , or the downward trend could signal that the company needs to loosen credit terms or more aggressively collect outstanding accounts .", "question": { "cloze_format": "(The) ___ best represents a positive product of a lower number of days’ sales in receivables ratio.", "normal_format": "Which of the following best represents a positive product of a lower number of days’ sales in receivables ratio?", "question_choices": [ "collection of receivables is quick, and cash can be used for other business expenditures", "collection of receivables is slow, keeping cash secured to receivables", "credit extension is lenient", "the lender only lends to the top 10% of potential creditors" ], "question_id": "fs-idm219197184", "question_text": "Which of the following best represents a positive product of a lower number of days’ sales in receivables ratio?" }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 0, "ans_text": "A" }, "bloom": null, "hl_context": "<hl> Receivables ratios show company performance in relation to current debt collection , as well as credit policy effect on sales growth . <hl> One receivables ratio is called the accounts receivable turnover ratio . This ratio determines how many times ( i . e . , how often ) accounts receivable are collected during an operating period and converted to cash ( see Figure 9.3 ) . A higher number of times indicates that receivables are collected quickly . This quick cash collection may be viewed as a positive occurrence , because liquidity improves , and the company may reinvest in its business sooner when the value of the dollar has more buying power ( time value of money ) . The higher number of times may also be a negative occurrence , signaling that credit extension terms are too tight , and it may exclude qualified consumers from purchasing . Excluding these customers means that they may take their business to a competitor , thus reducing potential sales .", "hl_sentences": "Receivables ratios show company performance in relation to current debt collection , as well as credit policy effect on sales growth .", "question": { "cloze_format": "Information that can best be elicited from a receivable ratio is ___ .", "normal_format": "What information can best be elicited from a receivable ratio?", "question_choices": [ "company performance with current debt collection", "credit extension effect on cash sales", "likelihood of future customer bankruptcy filings", "an increase in future credit sales to current customers" ], "question_id": "fs-idm185529840", "question_text": "What information can best be elicited from a receivable ratio?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 3, "ans_text": "D" }, "bloom": null, "hl_context": "<hl> Another earnings management opportunity may occur with the balance sheet aging method . <hl> <hl> Past-due categories could expand to encompass greater ( or fewer ) time periods , accounts receivable balances could be placed in different categories , or estimation percentages could change for each category . <hl> However , please remember that such changes would need to be considered acceptable by the company ’ s outside auditors during the annual independent audit . <hl> Legitimate current economic conditions could allow BWW to alter its estimation percentages , aging categories , and method used . <hl> <hl> Altering estimation percentages could mean an increase or decrease in percentages . <hl> If BWW decreases its income statement method percentage from 5 % of credit sales to 4 % of credit sales , the bad debt estimation would go from $ 22,500 ( 5 % × $ 450,000 ) in 2018 to $ 18,000 ( 4 % × $ 450,000 ) . The bad debt expense would decrease for the period , and net income would increase . If BWW decreases its balance sheet method percentage from 15 % of accounts receivable to 12 % of accounts receivable , the bad debt estimation would go from $ 12,750 ( 15 % × $ 85,000 ) in 2018 to $ 10,200 ( 12 % × $ 85,000 ) . The bad debt expense would decrease for the period and net income would increase . Accounts receivable would also increase , and allowances for doubtful accounts would decrease . As mentioned , this increase to earnings and asset increase is attractive to investors and lenders . Accounts receivable may also be manipulated to delay revenue recognition . These deferred earnings allow for a reduced tax obligation in the current year . A company involved in the sale or acquisition of a business may show a higher income level to increase the value of the business . <hl> Whatever the reason , a company often has the flexibility to manage their earnings slightly , given the amount of estimations and potential bad debt write-offs required to meet the revenue recognition and matching principles . <hl>", "hl_sentences": "Another earnings management opportunity may occur with the balance sheet aging method . Past-due categories could expand to encompass greater ( or fewer ) time periods , accounts receivable balances could be placed in different categories , or estimation percentages could change for each category . Legitimate current economic conditions could allow BWW to alter its estimation percentages , aging categories , and method used . Altering estimation percentages could mean an increase or decrease in percentages . Whatever the reason , a company often has the flexibility to manage their earnings slightly , given the amount of estimations and potential bad debt write-offs required to meet the revenue recognition and matching principles .", "question": { "cloze_format": "___ is not a way to manage earnings.", "normal_format": "Which of the following is not a way to manage earnings?", "question_choices": [ "Change the method for bad debt estimation.", "Change the figure for the uncollectible percentage.", "Under the balance sheet aging method, change the past-due categories.", "Change the dates of common stock issuance." ], "question_id": "fs-idm359182160", "question_text": "Which of the following is not a way to manage earnings?" }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 4, "ans_text": "Both A and C" }, "bloom": null, "hl_context": "<hl> Earnings management works within GAAP constraints to improve stakeholders ’ views of the company ’ s financial position . <hl> <hl> Earnings manipulation is noticeably different in that it typically ignores GAAP rules to alter earnings significantly . <hl> Carried to an extreme , manipulation can lead to fraudulent behavior by a company . The major problem in income manipulation is not in manipulating the numbers that constitute the financial reports . Instead , the bigger issue is the engineering of the short-term financial operating decisions . Some of the techniques used include applying universal standards , loose interpretations of revenue recognition , unofficial earnings measures , fair value accounting , and cooking the decision and not the books . 4 4 H . David Sherman and S . David Young . “ Where Financial Reporting Still Falls Short . ” Harvard Business Review . July-August 2016 . https://hbr.org/2016/07/where-financial-reporting-still-falls-short", "hl_sentences": "Earnings management works within GAAP constraints to improve stakeholders ’ views of the company ’ s financial position . Earnings manipulation is noticeably different in that it typically ignores GAAP rules to alter earnings significantly .", "question": { "cloze_format": "A statement that is true about earnings management is that ___.", "normal_format": "Which of the following is true about earnings management?", "question_choices": [ "It works within the constraints of GAAP.", "It works outside the constraints of GAAP.", "It tries to improve stakeholder’s views of the company’s financial position.", "Both B and C", "Both A and C" ], "question_id": "fs-idm359654480", "question_text": "Which of the following is true about earnings management?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 1, "ans_text": "B" }, "bloom": null, "hl_context": "Notes receivable have several defining characteristics that include principal , length of contract terms , and interest . <hl> The principal of a note is the initial loan amount , not including interest , requested by the customer . <hl> <hl> If a customer approaches a lender , requesting $ 2,000 , this amount is the principal . <hl> The date on which the security agreement is initially established is the issue date . <hl> A note ’ s maturity date is the date at which the principal and interest become due and payable . <hl> <hl> The maturity date is established in the initial note contract . <hl> For example , when the previously mentioned customer requested the $ 2,000 loan on January 1 , 2018 , terms of repayment included a maturity date of 24 months . This means that the loan will mature in two years , and the principal and interest are due at that time . The following journal entries occur at the note ’ s established start date . The first entry shows a note receivable in exchange for a product or service , and the second entry illustrates the note from the point of view that a $ 2,000 loan was issued by a financial institution to a customer ( borrower ) .", "hl_sentences": "The principal of a note is the initial loan amount , not including interest , requested by the customer . If a customer approaches a lender , requesting $ 2,000 , this amount is the principal . A note ’ s maturity date is the date at which the principal and interest become due and payable . The maturity date is established in the initial note contract .", "question": { "cloze_format": "A true statement of a maturity date is that ___ .", "normal_format": "Which of the following is true of a maturity date?", "question_choices": [ "It must be calculated in days, not in months or years.", "It is the date when principal and interest on a note are to be repaid to the lender.", "It is the date of establishment of note terms between a lender and customer.", "It is not a characteristic of a note receivable." ], "question_id": "fs-idm178755408", "question_text": "Which of the following is true of a maturity date?" }, "references_are_paraphrase": null } ]
9
9.1 Explain the Revenue Recognition Principle and How It Relates to Current and Future Sales and Purchase Transactions You own a small clothing store and offer your customers cash, credit card, or in-house credit payment options. Many of your customers choose to pay with a credit card or charge the purchase to their in-house credit accounts. This means that your store is owed money in the future from either the customer or the credit card company, depending on payment method. Regardless of credit payment method, your company must decide when to recognize revenue. Do you recognize revenue when the sale occurs or when cash payment is received? When do you recognize the expenses associated with the sale? How are these transactions recognized? Accounting Principles and Assumptions Regulating Revenue Recognition Revenue and expense recognition timing is critical to transparent financial presentation. GAAP governs recognition for publicly traded companies. Even though GAAP is required only for public companies, to display their financial position most accurately, private companies should manage their financial accounting using its rules. Two principles governed by GAAP are the revenue recognition principle and the matching principle. Both the revenue recognition principle and the matching principle give specific direction on revenue and expense reporting. The revenue recognition principle , which states that companies must recognize revenue in the period in which it is earned, instructs companies to recognize revenue when a four-step process is completed. This may not necessarily be when cash is collected. Revenue can be recognized when all of the following criteria have been met: There is credible evidence that an arrangement exists. Goods have been delivered or services have been performed. The selling price or fee to the buyer is fixed or can be reasonably determined. There is reasonable assurance that the amount owed to the seller is collectible. The accrual accounting method aligns with this principle, and it records transactions related to revenue earnings as they occur, not when cash is collected. The revenue recognition principle may be updated periodically to reflect more current rules for reporting. For example, a landscaping company signs a $600 contract with a customer to provide landscaping services for the next six months (assume the landscaping workload is distributed evenly throughout the six months). The customer sets up an in-house credit line with the company, to be paid in full at the end of the six months. The landscaping company records revenue earnings each month and provides service as planned. To align with the revenue recognition principle, the landscaping company will record one month of revenue ($100) each month as earned; they provided service for that month, even though the customer has not yet paid cash for the service. Let’s say that the landscaping company also sells gardening equipment. It sells a package of gardening equipment to a customer who pays on credit. The landscaping company will recognize revenue immediately, given that they provided the customer with the gardening equipment (product), even though the customer has not yet paid cash for the product. Accrual accounting also incorporates the matching principle (otherwise known as the expense recognition principle ), which instructs companies to record expenses related to revenue generation in the period in which they are incurred. The principle also requires that any expense not directly related to revenues be reported in an appropriate manner. For example, assume that a company paid $6,000 in annual real estate taxes. The principle has determined that costs cannot effectively be allocated based on an individual month’s sales; instead, it treats the expense as a period cost. In this case, it is going to record 1/12 of the annual expense as a monthly period cost. Overall, the “matching” of expenses to revenues projects a more accurate representation of company financials. When this matching is not possible, then the expenses will be treated as period costs. For example, when the landscaping company sells the gardening equipment, there are costs associated with that sale, such as the costs of materials purchased or shipping charges. The cost is reported in the same period as revenue associated with the sale. There cannot be a mismatch in reporting expenses and revenues; otherwise, financial statements are presented unfairly to stakeholders. Misreporting has a significant impact on company stakeholders. If the company delayed reporting revenues until a future period, net income would be understated in the current period. If expenses were delayed until a future period, net income would be overstated. Let’s turn to the basic elements of accounts receivable, as well as the corresponding transaction journal entries. Ethical Considerations Ethics in Revenue Recognition Because each industry typically has a different method for recognizing income, revenue recognition is one of the most difficult tasks for accountants, as it involves a number of ethical dilemmas related to income reporting. To provide an industry-wide approach, Accounting Standards Update No. 2014-09 and other related updates were implemented to clarify revenue recognition rules. The American Institute of Certified Public Accountants (AICPA) announced that these updates would replace U.S. GAAP’s current industry-specific revenue recognition practices with a principle-based approach, potentially affecting both day-to-day business accounting and the execution of business contracts with customers. 1 The AICPA and the International Federation of Accountants (IFAC) require professional accountants to act with due care and to remain abreast of new accounting rules and methods of accounting for different transactions, including revenue recognition. 1 American Institute of Certified Public Accountants (AICPA). “Revenue from Contracts with Customers.” Revenue Recognition . n.d. https://www.aicpa.org/interestareas/frc/accountingfinancialreporting/revenuerecognition.html The IFAC emphasizes the role of professional accountants working within a business in ensuring the quality of financial reporting: “Management is responsible for the financial information produced by the company. As such, professional accountants in businesses therefore have the task of defending the quality of financial reporting right at the source where the numbers and figures are produced!” 2 In accordance with proper revenue recognition, accountants do not recognize revenue before it is earned. 2 International Federation of Accountants (IFAC). “Roles and Importance of Professional Accountants in Business.” n.d. https://www.ifac.org/news-events/2013-10/roles-and-importance-professional-accountants-business Concepts In Practice Gift Card Revenue Recognition Gift cards have become an essential part of revenue generation and growth for many businesses. Although they are practical for consumers and low cost to businesses, navigating revenue recognition guidelines can be difficult. Gift cards with expiration dates require that revenue recognition be delayed until customer use or expiration. However, most gift cards now have no expiration date. So, when do you recognize revenue? Companies may need to provide an estimation of projected gift card revenue and usage during a period based on past experience or industry standards. There are a few rules governing reporting. If the company determines that a portion of all of the issued gift cards will never be used, they may write this off to income. In some states, if a gift card remains unused, in part or in full, the unused portion of the card is transferred to the state government. It is considered unclaimed property for the customer, meaning that the company cannot keep these funds as revenue because, in this case, they have reverted to the state government. Short-Term Revenue Recognition Examples As mentioned, the revenue recognition principle requires that, in some instances, revenue is recognized before receiving a cash payment. In these situations, the customer still owes the company money. This money owed to the company is a type of receivable for the company and a payable for the company’s customer. A receivable is an outstanding amount owed from a customer. One specific receivable type is called accounts receivable. Accounts receivable is an outstanding customer debt on a credit sale. The company expects to receive payment on accounts receivable within the company’s operating period (less than a year). Accounts receivable is considered an asset, and it typically does not include an interest payment from the customer. Some view this account as extending a line of credit to a customer. The customer would then be sent an invoice with credit payment terms. If the company has provided the product or service at the time of credit extension, revenue would also be recognized. For example, Billie’s Watercraft Warehouse (BWW) sells various watercraft vehicles. They extend a credit line to customers purchasing vehicles in bulk. A customer bought 10 Jet Skis on credit at a sales price of $100,000. The cost of the sale to BWW is $70,000. The following journal entries occur. Accounts Receivable increases (debit) and Sales Revenue increases (credit) for $100,000. Accounts Receivable recognizes the amount owed from the customer, but not yet paid. Revenue recognition occurs because BWW provided the Jet Skis and completed the earnings process. Cost of Goods Sold increases (debit) and Merchandise Inventory decreases (credit) for $70,000, the expense associated with the sale. By recording both a sale and its related cost entry, the matching principle requirement is met. When the customer pays the amount owed, the following journal entry occurs. Cash increases (debit) and Accounts Receivable decreases (credit) for the full amount owed. If the customer made only a partial payment, the entry would reflect the amount of the payment. For example, if the customer paid only $75,000 of the $100,000 owed, the following entry would occur. The remaining $25,000 owed would remain outstanding, reflected in Accounts Receivable. Another credit transaction that requires recognition is when a customer pays with a credit card ( Visa and MasterCard , for example). This is different from credit extended directly to the customer from the company. In this case, the third-party credit card company accepts the payment responsibility. This reduces the risk of nonpayment, increases opportunities for sales, and expedites payment on accounts receivable. The tradeoff for the company receiving these benefits from the credit card company is that a fee is charged to use this service. The fee can be a flat figure per transaction, or it can be a percentage of the sales price. Using BWW as the example, let’s say one of its customers purchased a canoe for $300, using his or her Visa credit card. The cost to BWW for the canoe is $150. Visa charges BWW a service fee equal to 5% of the sales price. At the time of sale, the following journal entries are recorded. Accounts Receivable: Visa increases (debit) for the sale amount ($300) less the credit card fee ($15), for a $285 Accounts Receivable balance due from Visa . BWW’s Credit Card Expense increases (debit) for the amount of the credit card fee ($15; 300 × 5%), and Sales Revenue increases (credit) for the original sales amount ($300). BWW recognizes revenue as earned for this transaction because it provided the canoe and completed the earnings process. Cost of Goods Sold increases (debit) and Merchandise Inventory decreases (credit) for $150, the expense associated with the sale. As with the previous example, by recording both a sale and cost entry, the matching principle requirement is met. When Visa pays the amount owed to BWW, the following entry occurs in BWW’s records. Cash increases (debit) and Accounts Receivable: Visa decreases (credit) for the full amount owed, less the credit card fee. Once BWW receives the cash payment from Visa , it may use those funds in other business activities. An alternative to the journal entries shown is that the credit card company, in this case Visa , gives the merchant immediate credit in its cash account for the $285 due the merchant, without creating an account receivable. If that policy were in effect for this transaction, the following single journal entry would replace the prior two journal entry transactions. In the immediate cash payment method, an account receivable would not need to be recorded and then collected. The separate journal entry—to record the costs of goods sold and to reduce the canoe inventory that reflects the $150 cost of the sale—would still be the same. Here’s a final credit transaction to consider. A company allows a sales discount on a purchase if a customer charges a purchase but makes the payment within a stated period of time, such as 10 or 15 days from the point of sale. In such a situation, a customer would see credit terms in the following form: 2/10, n/30. This particular example shows that a customer who pays his or her account within 10 days will receive a 2% discount. Otherwise, the customer will have 30 days from the date of the purchase to pay in full, but will not receive a discount. Both sales discounts and purchase discounts were addressed in detail in Merchandising Transactions . Your Turn Maine Lobster Market Maine Lobster Market (MLM) provides fresh seafood products to customers. It allows customers to pay with cash, an in-house credit account, or a credit card. The credit card company charges Maine Lobster Market a 4% fee, based on credit sales using its card. From the following transactions, prepare journal entries for Maine Lobster Market. Aug. 5 Pat paid $800 cash for lobster. The cost to MLM was $480. Aug. 10 Pat purchased 30 pounds of shrimp at a sales price per pound of $25. The cost to MLM was $18.50 per pound and is charged to Pat’s in-store account. Aug. 19 Pat purchased $1,200 of fish with a credit card. The cost to MLM is $865. Solution Your Turn Jamal’s Music Supply Jamal’s Music Supply allows customers to pay with cash or a credit card. The credit card company charges Jamal’s Music Supply a 3% fee, based on credit sales using its card. From the following transactions, prepare journal entries for Jamal’s Music Supply. May 10 Kerry paid $1,790 for music supplies with a credit card. The cost to Jamal’s Music Supply was $1,100. May 19 Kerry purchased 80 drumstick pairs at a sales price per pair of $14 with a credit card. The cost to Jamal’s Music Supply was $7.30 per pair. May 28 Kerry purchased $345 of music supplies with cash. The cost to Jamal’s Music Supply was $122. Solution 9.2 Account for Uncollectible Accounts Using the Balance Sheet and Income Statement Approaches You lend a friend $500 with the agreement that you will be repaid in two months. At the end of two months, your friend has not repaid the money. You continue to request the money each month, but the friend has yet to repay the debt. How does this affect your finances? Think of this on a larger scale. A bank lends money to a couple purchasing a home (mortgage). The understanding is that the couple will make payments each month toward the principal borrowed, plus interest. As time passes, the loan goes unpaid. What happens when a loan that was supposed to be paid is not paid? How does this affect the financial statements for the bank? The bank may need to consider ways to recognize this bad debt. Fundamentals of Bad Debt Expenses and Allowances for Doubtful Accounts Bad debts are uncollectible amounts from customer accounts. Bad debt negatively affects accounts receivable (see Figure 9.2 ). When future collection of receivables cannot be reasonably assumed, recognizing this potential nonpayment is required. There are two methods a company may use to recognize bad debt: the direct write-off method and the allowance method. The direct write-off method delays recognition of bad debt until the specific customer accounts receivable is identified. Once this account is identified as uncollectible, the company will record a reduction to the customer’s accounts receivable and an increase to bad debt expense for the exact amount uncollectible. Under generally accepted accounting principles ( GAAP ), the direct write-off method is not an acceptable method of recording bad debts, because it violates the matching principle. For example, assume that a credit transaction occurs in September 2018 and is determined to be uncollectible in February 2019. The direct write-off method would record the bad debt expense in 2019, while the matching principle requires that it be associated with a 2018 transaction, which will better reflect the relationship between revenues and the accompanying expenses. This matching issue is the reason accountants will typically use one of the two accrual-based accounting methods introduced to account for bad debt expenses. It is important to consider other issues in the treatment of bad debts. For example, when companies account for bad debt expenses in their financial statements, they will use an accrual-based method; however, they are required to use the direct write-off method on their income tax returns. This variance in treatment addresses taxpayers’ potential to manipulate when a bad debt is recognized. Because of this potential manipulation, the Internal Revenue Service (IRS) requires that the direct write-off method must be used when the debt is determined to be uncollectible, while GAAP still requires that an accrual-based method be used for financial accounting statements. For the taxpayer, this means that if a company sells an item on credit in October 2018 and determines that it is uncollectible in June 2019, it must show the effects of the bad debt when it files its 2019 tax return. This application probably violates the matching principle, but if the IRS did not have this policy, there would typically be a significant amount of manipulation on company tax returns. For example, if the company wanted the deduction for the write-off in 2018, it might claim that it was actually uncollectible in 2018, instead of in 2019. The final point relates to companies with very little exposure to the possibility of bad debts, typically, entities that rarely offer credit to its customers. Assuming that credit is not a significant component of its sales, these sellers can also use the direct write-off method. The companies that qualify for this exemption, however, are typically small and not major participants in the credit market. Thus, virtually all of the remaining bad debt expense material discussed here will be based on an allowance method that uses accrual accounting, the matching principle, and the revenue recognition rules under GAAP. For example, a customer takes out a $15,000 car loan on August 1, 2018 and is expected to pay the amount in full before December 1, 2018. For the sake of this example, assume that there was no interest charged to the buyer because of the short-term nature or life of the loan. When the account defaults for nonpayment on December 1, the company would record the following journal entry to recognize bad debt. Bad Debt Expense increases (debit), and Accounts Receivable decreases (credit) for $15,000. If, in the future, any part of the debt is recovered, a reversal of the previously written-off bad debt, and the collection recognition is required. Let’s say this customer unexpectedly pays in full on May 1, 2019, the company would record the following journal entries (note that the company’s fiscal year ends on June 30) The first entry reverses the bad debt write-off by increasing Accounts Receivable (debit) and decreasing Bad Debt Expense (credit) for the amount recovered. The second entry records the payment in full with Cash increasing (debit) and Accounts Receivable decreasing (credit) for the amount received of $15,000. As you’ve learned, the delayed recognition of bad debt violates GAAP, specifically the matching principle. Therefore, the direct write-off method is not used for publicly traded company reporting; the allowance method is used instead. The allowance method is the more widely used method because it satisfies the matching principle. The allowance method estimates bad debt during a period, based on certain computational approaches. The calculation matches bad debt with related sales during the period. The estimation is made from past experience and industry standards. When the estimation is recorded at the end of a period, the following entry occurs. The journal entry for the Bad Debt Expense increases (debit) the expense’s balance, and the Allowance for Doubtful Accounts increases (credit) the balance in the Allowance. The allowance for doubtful accounts is a contra asset account and is subtracted from Accounts Receivable to determine the Net Realizable Value of the Accounts Receivable account on the balance sheet. A contra account has an opposite normal balance to its paired account, thereby reducing or increasing the balance in the paired account at the end of a period; the adjustment can be an addition or a subtraction from a controlling account. In the case of the allowance for doubtful accounts, it is a contra account that is used to reduce the Controlling account, Accounts Receivable. At the end of an accounting period, the Allowance for Doubtful Accounts reduces the Accounts Receivable to produce Net Accounts Receivable. Note that allowance for doubtful accounts reduces the overall accounts receivable account, not a specific accounts receivable assigned to a customer. Because it is an estimation, it means the exact account that is (or will become) uncollectible is not yet known. To demonstrate the treatment of the allowance for doubtful accounts on the balance sheet, assume that a company has reported an Accounts Receivable balance of $90,000 and a Balance in the Allowance of Doubtful Accounts of $4,800. The following table reflects how the relationship would be reflected in the current (short-term) section of the company’s Balance Sheet. There is one more point about the use of the contra account, Allowance for Doubtful Accounts. In this example, the $85,200 total is the net realizable value, or the amount of accounts anticipated to be collected. However, the company is owed $90,000 and will still try to collect the entire $90,000 and not just the $85,200. Under the balance sheet method of calculating bad debt expenses, if there is already a balance in Allowance for Doubtful Accounts from a previous period and accounts written off in the current year, this must be considered before the adjusting entry is made. For example, if a company already had a credit balance from the prior period of $1,000, plus any accounts that have been written off this year, and a current period estimated balance of $2,500, the company would need to subtract the prior period’s credit balance from the current period’s estimated credit balance in order to calculate the amount to be added to the Allowance for Doubtful Accounts. Therefore, the adjusting journal entry would be as follows. If a company already had a debit balance from the prior period of $1,000, and a current period estimated balance of $2,500, the company would need to add the prior period’s debit balance to the current period’s estimated credit balance. Therefore, the adjusting journal entry would be as follows. When a specific customer has been identified as an uncollectible account, the following journal entry would occur. Allowance for Doubtful Accounts decreases (debit) and Accounts Receivable for the specific customer also decreases (credit). Allowance for doubtful accounts decreases because the bad debt amount is no longer unclear. Accounts receivable decreases because there is an assumption that no debt will be collected on the identified customer’s account. Let’s say that the customer unexpectedly pays on the account in the future. The following journal entries would occur. The first entry reverses the previous entry where bad debt was written off. This reinstatement requires Accounts Receivable: Customer to increase (debit), and Allowance for Doubtful Accounts to increase (credit). The second entry records the payment on the account. Cash increases (debit) and Accounts Receivable: Customer decreases (credit) for the amount received. To compute the most accurate estimation possible, a company may use one of three methods for bad debt expense recognition: the income statement method, balance sheet method, or balance sheet aging of receivables method. Think It Through Bad Debt Estimation As the accountant for a large publicly traded food company, you are considering whether or not you need to change your bad debt estimation method. You currently use the income statement method to estimate bad debt at 4.5% of credit sales. You are considering switching to the balance sheet aging of receivables method. This would split accounts receivable into three past- due categories and assign a percentage to each group. While you know that the balance sheet aging of receivables method is more accurate, it does require more company resources (e.g., time and money) that are currently applied elsewhere in the business. Using the income statement method is acceptable under generally accepted accounting principles (GAAP), but should you switch to the more accurate method even if your resources are constrained? Do you have a responsibility to the public to change methods if you know one is a better estimation? Income Statement Method for Calculating Bad Debt Expenses The income statement method (also known as the percentage of sales method ) estimates bad debt expenses based on the assumption that at the end of the period, a certain percentage of sales during the period will not be collected. The estimation is typically based on credit sales only, not total sales (which include cash sales). In this example, assume that any credit card sales that are uncollectible are the responsibility of the credit card company. It may be obvious intuitively, but, by definition, a cash sale cannot become a bad debt, assuming that the cash payment did not entail counterfeit currency. The income statement method is a simple method for calculating bad debt, but it may be more imprecise than other measures because it does not consider how long a debt has been outstanding and the role that plays in debt recovery. To illustrate, let’s continue to use Billie’s Watercraft Warehouse (BWW) as the example. Billie’s end-of-year credit sales totaled $458,230. BWW estimates that 5% of its overall credit sales will result in bad debt. The following adjusting journal entry for bad debt occurs. Bad Debt Expense increases (debit), and Allowance for Doubtful Accounts increases (credit) for $22,911.50 ($458,230 × 5%). This means that BWW believes $22,911.50 will be uncollectible debt. Let’s say that on April 8, it was determined that Customer Robert Craft’s account was uncollectible in the amount of $5,000. The following entry occurs. In this case, Allowance for Doubtful Accounts decreases (debit) and Accounts Receivable: Craft decreases (credit) for the known uncollectible amount of $5,000. On June 5, Craft unexpectedly makes a partial payment on his account in the amount of $3,000. The following journal entries show the reinstatement of bad debt and the subsequent payment. The outstanding balance of $2,000 that Craft did not repay will remain as bad debt. Your Turn Heating and Air Company You run a successful heating and air conditioning company. Your net credit sales, accounts receivable, and allowance for doubtful accounts figures for year-end 2018, follow. Compute bad debt estimation using the income statement method, where the percentage uncollectible is 5%. Prepare the journal entry for the income statement method of bad debt estimation. Compute bad debt estimation using the balance sheet method of percentage of receivables, where the percentage uncollectible is 9%. Prepare the journal entry for the balance sheet method bad debt estimation. Solution $41,570; $831,400 × 5% $20,056.50; $222,850 × 9% Balance Sheet Method for Calculating Bad Debt Expenses The balance sheet method (also known as the percentage of accounts receivable method ) estimates bad debt expenses based on the balance in accounts receivable. The method looks at the balance of accounts receivable at the end of the period and assumes that a certain amount will not be collected. Accounts receivable is reported on the balance sheet; thus, it is called the balance sheet method. The balance sheet method is another simple method for calculating bad debt, but it too does not consider how long a debt has been outstanding and the role that plays in debt recovery. There is a variation on the balance sheet method, however, called the aging method that does consider how long accounts receivable have been owed, and it assigns a greater potential for default to those debts that have been owed for the longest period of time. Continuing our examination of the balance sheet method, assume that BWW’s end-of-year accounts receivable balance totaled $324,850. This entry assumes a zero balance in Allowance for Doubtful Accounts from the prior period. BWW estimates 15% of its overall accounts receivable will result in bad debt. The following adjusting journal entry for bad debt occurs. Bad Debt Expense increases (debit), and Allowance for Doubtful Accounts increases (credit) for $48,727.50 ($324,850 × 15%). This means that BWW believes $48,727.50 will be uncollectible debt. Let’s consider that BWW had a $23,000 credit balance from the previous period. The adjusting journal entry would recognize the following. This is different from the last journal entry, where bad debt was estimated at $48,727.50. That journal entry assumed a zero balance in Allowance for Doubtful Accounts from the prior period. This journal entry takes into account a credit balance of $23,000 and subtracts the prior period’s balance from the estimated balance in the current period of $48,727.50. Balance Sheet Aging of Receivables Method for Calculating Bad Debt Expenses The balance sheet aging of receivables method estimates bad debt expenses based on the balance in accounts receivable, but it also considers the uncollectible time period for each account. The longer the time passes with a receivable unpaid, the lower the probability that it will get collected. An account that is 90 days overdue is more likely to be unpaid than an account that is 30 days past due. With this method, accounts receivable is organized into categories by length of time outstanding, and an uncollectible percentage is assigned to each category. The length of uncollectible time increases the percentage assigned. For example, a category might consist of accounts receivable that is 0–30 days past due and is assigned an uncollectible percentage of 6%. Another category might be 31–60 days past due and is assigned an uncollectible percentage of 15%. All categories of estimated uncollectible amounts are summed to get a total estimated uncollectible balance. That total is reported in Bad Debt Expense and Allowance for Doubtful Accounts, if there is no carryover balance from a prior period. If there is a carryover balance, that must be considered before recording Bad Debt Expense. The balance sheet aging of receivables method is more complicated than the other two methods, but it tends to produce more accurate results. This is because it considers the amount of time that accounts receivable has been owed, and it assumes that the longer the time owed, the greater the possibility that individual accounts receivable will prove to be uncollectible. Looking at BWW, it has an accounts receivable balance of $324,850 at the end of the year. The company splits its past-due accounts into three categories: 0–30 days past due, 31–90 days past due, and over 90 days past due. The uncollectible percentages and the accounts receivable breakdown are shown here. For each of the individual categories, the accountant multiplies the uncollectible percentage by the accounts receivable total for that category to get the total balance of estimated accounts that will prove to be uncollectible for that category. Then all of the category estimates are added together to get one total estimated uncollectible balance for the period. The entry for bad debt would be as follows, if there was no carryover balance from the prior period. Bad Debt Expense increases (debit) as does Allowance for Doubtful Accounts (credit) for $58,097. BWW believes that $58,097 will be uncollectible debt. Let’s consider a situation where BWW had a $20,000 debit balance from the previous period. The adjusting journal entry would recognize the following. This is different from the last journal entry, where bad debt was estimated at $58,097. That journal entry assumed a zero balance in Allowance for Doubtful Accounts from the prior period. This journal entry takes into account a debit balance of $20,000 and adds the prior period’s balance to the estimated balance of $58,097 in the current period. You may notice that all three methods use the same accounts for the adjusting entry; only the method changes the financial outcome. Also note that it is a requirement that the estimation method be disclosed in the notes of financial statements so stakeholders can make informed decisions. Concepts In Practice Generally Accepted Accounting Principles As of January 1, 2018, GAAP requires a change in how health-care entities record bad debt expense. Before this change, these entities would record revenues for billed services, even if they did not expect to collect any payment from the patient. This uncollectible amount would then be reported in Bad Debt Expense. Under the new guidance, the bad debt amount may only be recorded if there is an unexpected circumstance that prevented the patient from paying the bill, and it may only be calculated from the amount that the providing entity anticipated collecting. For example, a patient receives medical services at a local hospital that cost $1,000. The hospital knows in advance that the patient will pay only $100 of the amount owed. The previous GAAP rules would allow the company to write off $900 to bad debt. Under the current rule, the company may only consider revenue to be the expected amount of $100. For example, if the patient ran into an unexpected job loss and is able to pay only $20 of the $100 expected, the hospital would record the $20 to revenue and the $80 ($100 – $20) as a write-off to bad debt. This is a significant change in revenue reporting and bad debt expense. Health-care entities will more than likely see a decrease in bad debt expense and revenues as a result of this change. 3 3 Tara Bannow. “New Bad Debt Accounting Standards Likely to Remake Community Benefit Reporting.” Modern Healthcare . March 17, 2018. http://www.modernhealthcare.com/article/20180317/NEWS/180319904 9.3 Determine the Efficiency of Receivables Management Using Financial Ratios You received an unexpected tax refund this year and want to invest the money in a profitable and growing company. After conducting research, you determine that it is important for a company to collect on outstanding debt quickly, while showing a willingness to offer customers credit options to increase sales opportunities, among other things. You are new to investing, so where do you begin? Stakeholders, such as investors, lenders, and management, look to financial statement data to make informed decisions about a company’s financial position. They will look at each statement—as well as ratio analysis—for trends, industry comparisons, and past performance to help make financing determinations. Because you are reviewing companies for quick debt collection, as well as credit extension to boost sales, you would consider receivables ratios to guide your decision. Discuss the Role of Accounting for Receivables in Earnings Management will explain and demonstrate two popular ratios—the accounts receivable turnover ratio and the number of days’ sales in receivables ratio—used to evaluate a company’s receivables experiences. It is important to remember, however, that for a comprehensive evaluation of a company’s true potential as an investment, you need to consider other types of ratios, in addition to the receivables ratios. For example, you might want to look at the company’s profitability, solvency, and liquidity performances using ratios. (See Appendix A for more information on ratios.) Basic Functions of the Receivables Ratios Receivables ratios show company performance in relation to current debt collection, as well as credit policy effect on sales growth. One receivables ratio is called the accounts receivable turnover ratio . This ratio determines how many times (i.e., how often) accounts receivable are collected during an operating period and converted to cash (see Figure 9.3 ). A higher number of times indicates that receivables are collected quickly. This quick cash collection may be viewed as a positive occurrence, because liquidity improves, and the company may reinvest in its business sooner when the value of the dollar has more buying power (time value of money). The higher number of times may also be a negative occurrence, signaling that credit extension terms are too tight, and it may exclude qualified consumers from purchasing. Excluding these customers means that they may take their business to a competitor, thus reducing potential sales. In contrast, a lower number of times indicates that receivables are collected at a slower rate. A slower collection rate could signal that lending terms are too lenient; management might consider tightening lending opportunities and more aggressively pursuing outstanding debt. The lower turnover also shows that the company has cash tied up in receivable longer, thus hindering its ability to reinvest this cash in other current projects. The lower turnover rate may signal a high level of bad debt accounts. The determination of a high or low turnover rate really depends on the standards of the company’s industry. Another receivables ratio one must consider is the number of days’ sales in receivables ratio . This ratio is similar to accounts receivable turnover in that it shows the expected days it will take to convert accounts receivable into cash. The reflected outcome is in number of days, rather than in number of times. Companies often have outstanding debt that requires scheduled payments. If it takes longer for a company to collect on outstanding receivables, this means it may not be able to meet its current obligations. It helps to know the number of days it takes to go through the accounts receivable collection cycle so a company can plan its debt repayments; this receivables ratio also signals how efficient its collection procedures are. As with the accounts receivable turnover ratio, there are positive and negative elements with a smaller and larger amount of days; in general, the fewer number of collection days on accounts receivable, the better. To illustrate the use of these ratios to make financial decisions, let’s use Billie’s Watercraft Warehouse (BWW) as the example. Included are the comparative income statement ( Figure 9.4 ) and the comparative balance sheet ( Figure 9.5 ) for BWW, followed by competitor ratio information, for the years 2016, 2017, and 2018 as shown in Table 9.1 . Comparison of Ratios: Industry Competitor to BWW Year Accounts Receivable Turnover Ratio Number of Days’ Sales in Receivables Ratio 2016 4.89 times 80 days 2017 4.92 times 79.23 days 2018 5.25 times 76.44 days Table 9.1 Industry Competitor Ratios for the years 2016, 2017, and 2018. Your Turn The Investor You are an investor looking to contribute financially to either Company A or Company B. The following select financial information follows. Based on the information provided: Compute the accounts receivable turnover ratio Compute the number of days’ sales in receivables ratio for both Company A and Company B (round all answers to two decimal places) Interpret the outcomes, stating which company you would invest in and why Solution Company A: ART = 8.46 times, Days’ Sales = 43.14 days, Company B: ART = 6.13 times, Days’ Sales = 59.54 days. Upon initial review of this limited information, Company A seems to be the better choice, since their turnover ratio is higher and the collection time is lower with 43.14 days. One might want more information on trends for each company with these ratios and a comparison to others in the same industry. More information is needed before making an informed decision. Accounts Receivable Turnover Ratio The ratio to determine accounts receivable turnover is as follows. Net credit sales are sales made on credit only; cash sales are not included because they do not produce receivables. However, many companies do not report credit sales separate from cash sales, so “net sales” may be substituted for “net credit sales” in this case. Beginning and ending accounts receivable refer to the beginning and ending balances in accounts receivable for the period. The beginning accounts receivable balance is the same figure as the ending accounts receivable balance from the prior period. Use this formula to compute BWW’s accounts receivable turnover for 2017 and 2018. The accounts receivable turnover ratio for 2017 is 5 × ($400,000/$80,000). Net credit sales for 2017 are $400,000, so Average accounts receivable = ( $ 70,000 + $ 90,000 ) 2 = $ 80,000 Average accounts receivable = ( $ 70,000 + $ 90,000 ) 2 = $ 80,000 The accounts receivable turnover ratio for 2018 is 5.14 times (rounded to two decimal places). Net credit sales for 2018 are $450,000, so Average accounts receivable = ( $ 90,000 + $ 85,000 ) 2 = $ 87,500 Average accounts receivable = ( $ 90,000 + $ 85,000 ) 2 = $ 87,500 The outcome for 2017 means that the company turns over receivables (converts receivables into cash) 5 times during the year. The outcome for 2018 shows that BWW converts cash at a quicker rate of 5.14 times. There is a trend increase from 2017 to 2018. BWW sells various watercraft. These products tend to have a higher sales price, making a customer more likely to pay with credit. This can also increase the length of debt repayment. Comparing to another company in the industry, BWW’s turnover rate is standard. To increase the turnover rate, BWW can consider extending credit to more customers who the company has determined will pay on a quicker basis or schedule, or BWW can more aggressively pursue the outstanding debt from current customers. Number of Days’ Sales in Receivables Ratio The ratio to determine number of days’ sales in receivables is as follows. The numerator is 365, the number of days in the year. Because the accounts receivable turnover ratio determines an average accounts receivable figure, the outcome for the days’ sales in receivables is also an average number. Using this formula, compute BWW’s number of days’ sales in receivables ratio for 2017 and 2018. The ratio for 2017 is 73 days (365/5), and for 2018 is 71.01 days (365/5.14), rounded. This means it takes 73 days in 2017 and 71.01 days in 2018 to complete the collection cycle, which is a decrease from 2017 to 2018. A downward trend is a positive for the company, and BWW outperforms the competition slightly. This is good because BWW can use the cash toward other business expenditures, or the downward trend could signal that the company needs to loosen credit terms or more aggressively collect outstanding accounts. Looking at both ratios, BWW seems well positioned within the industry, and a potential investor or lender may be more apt to contribute financially to the organization with this continued positive trend. Link to Learning American Superconductor Corporation specializes in the production and service of energy-efficient wind turbine systems, as well as energy grid construction solutions. On the company’s 2018–2019 financial statements, the accounts receivable turnover ratio is approximately 6.32 times, and the number of day’s sales in receivables ratio is approximately 58 days. This site providing American Superconductor Corporation’s current financial statements is available for review. 9.4 Discuss the Role of Accounting for Receivables in Earnings Management Assume that you are an accountant at a large public corporation and are on a team responsible for preparing financial statements. In one team discussion, a dilemma arises: What is the best way to report earnings to create the most favorable possible financial position for your company, while still complying in an ethical manner and also complying fully with generally accepted accounting procedures (GAAP)? Your company is required to follow GAAP rules, but is there a way to comply with these rules while showing the company in its best light? How does receivables accounting factor into this quandary? Before examining potential ways to improve the company’s financial image, let’s consider some important conditions. To begin, if the company is publicly traded on a national or regional stock exchange, it is subject to the accounting and financial regulations set by the Securities and Exchange Commission (SEC). Included in these rules is the requirement that each publicly traded company must prepare and make public each year its annual report, including the results of an extensive audit procedure performed by a major public accounting firm. In the process of auditing the company, the auditing firm will conduct tests to determine whether, in the auditor’s opinion, the financial statements accurately reflect the financial position of the company. If the auditor feels that transactions, financial schedules, or other records do not accurately reflect the company’s performance for the past year, then the auditor can issue a negative audit report, which could have major negative effects on the company’s image in the financial community. To sum up this issue, any attempts by companies to make their financial position look better must be based on assumptions by the company that can be verified by an outside, independent party, such as a major public accounting firm. As you learn about this topic, assume that any recommendations suggested must be legitimate changes in assumptions by the company and that the recommendations will pass public examination and scrutiny. Earnings management works within GAAP constraints to improve stakeholders’ views of the company’s financial position. Earnings manipulation is noticeably different in that it typically ignores GAAP rules to alter earnings significantly. Carried to an extreme, manipulation can lead to fraudulent behavior by a company. The major problem in income manipulation is not in manipulating the numbers that constitute the financial reports. Instead, the bigger issue is the engineering of the short-term financial operating decisions. Some of the techniques used include applying universal standards, loose interpretations of revenue recognition, unofficial earnings measures, fair value accounting, and cooking the decision and not the books. 4 4 H. David Sherman and S. David Young. “Where Financial Reporting Still Falls Short.” Harvard Business Review . July-August 2016. https://hbr.org/2016/07/where-financial-reporting-still-falls-short A company may be enticed to manipulate earnings for several reasons. It may want to show a healthier income level, meet or exceed market expectations, and receive management bonuses. This can produce more investment interest from potential investors. An increase to receivables and inventory can help a business to secure more borrowed funds. Ethical Considerations Improper Revenue Recognition Leads to New Accounting Laws and Regulations The complete financial collapse of the Enron Corporation was a catalyst for major changes in the accounting profession. Fraudulent revenue recognition and financial statement manipulation at Enron —an energy, commodities, and services company—helped provide support for the implementation of the Sarbanes-Oxley Act of 2002 (SOX). A federal law, SOX included the creation of the Public Company Accounting Oversight Board (PCAOB), a regulatory agency to oversee auditors and ensure compliance with SOX requirements. The PCAOB is charged by the Sarbanes-Oxley Act of 2002 with establishing auditing and professional practice standards for registered public accounting firms to follow in the preparation and issuing of audit reports. 5 The PCAOB regulates how publicly traded companies are audited and provides requirements and ethical standards that direct professional accountants in their work with publicly traded companies. Visit their website at www.pcaobus.org to learn more. 5 Public Company Accounting Oversight Board (PCAOB). “Standards.” n.d. https://pcaobus.org/Standards Accounts receivable may also be manipulated to delay revenue recognition. These deferred earnings allow for a reduced tax obligation in the current year. A company involved in the sale or acquisition of a business may show a higher income level to increase the value of the business. Whatever the reason, a company often has the flexibility to manage their earnings slightly, given the amount of estimations and potential bad debt write-offs required to meet the revenue recognition and matching principles. One area of estimation involves bad debt in relation to accounts receivable. As you’ve learned, the income statement method, balance sheet method, and the balance sheet aging method all require estimations of bad debt with receivables. The percentage uncollectible is supposed to be presented as an educated estimation based on past performance, industry standards, and other economic factors. However, this estimation is just that—an estimation—and it can be slightly manipulated or managed to overstate or understate bad debt, as well as accounts receivable. For example, a company does not usually benefit from bad debt write-off. It might legitimately—if past experience justifies the change—alter past-due dates to current accounts to avoid having to write off bad debt. This overstates accounts receivable and understates bad debt. The company could also change the percentage uncollectible to a lower or higher figure, if its financial information and the present economic environment justify the change. The company could change the percentage from 2% uncollectible to 1% uncollectible. This increases accounts receivable and potential earnings and reduces bad debt expenses in the current period. Link to Learning The Beneish M-Score is an earnings manipulation measurement system that incorporates eight financial ratios to identify potentially compromised companies. In 2000, a group of students from Cornell University used this measurement to sell all the “Cayuga Fund” stock holdings in Enron , one year before the total collapse of company. Read this article on the Cornell University Enron Case Study to learn more. Let’s take Billie’s Watercraft Warehouse (BWW), for example. BWW had the following net credit sales and accounts receivable from 2016–2018. It also used the following percentage calculations for doubtful accounts under each bad debt estimation method. Legitimate current economic conditions could allow BWW to alter its estimation percentages, aging categories, and method used. Altering estimation percentages could mean an increase or decrease in percentages. If BWW decreases its income statement method percentage from 5% of credit sales to 4% of credit sales, the bad debt estimation would go from $22,500 (5% × $450,000) in 2018 to $18,000 (4% × $450,000). The bad debt expense would decrease for the period, and net income would increase. If BWW decreases its balance sheet method percentage from 15% of accounts receivable to 12% of accounts receivable, the bad debt estimation would go from $12,750 (15% × $85,000) in 2018 to $10,200 (12% × $85,000). The bad debt expense would decrease for the period and net income would increase. Accounts receivable would also increase, and allowances for doubtful accounts would decrease. As mentioned, this increase to earnings and asset increase is attractive to investors and lenders. Another earnings management opportunity may occur with the balance sheet aging method. Past-due categories could expand to encompass greater (or fewer) time periods, accounts receivable balances could be placed in different categories, or estimation percentages could change for each category. However, please remember that such changes would need to be considered acceptable by the company’s outside auditors during the annual independent audit. To demonstrate the recommendation, assume that BWW has three categories: 0–30 days past due, 31–90 days past due, and over 90 days past due. These categories could change to 0–60 days, 61–120 days, and over 120 days. This could move accounts that previously had a higher bad debt percentage assigned to them into a lower percentage category. This category shift could produce an increase to accounts receivable, and a decrease to bad debt expense; thus, increasing net income estimation percentages can change within each category. The following is the original uncollectible distribution for BWW in 2018. The following is the uncollectible percentage distribution change. Comparing the two outcomes, the original uncollectible figure was $15,500 and the changed uncollectible figure is $12,450. This reduction produces a higher accounts receivable balance, a lower bad debt expense, and a higher net income. A company may also change the estimation method to produce a different net income outcome. For example, BWW may go from the income statement method to the balance sheet method. However, as mentioned, the change would have to be considered to reflect the company’s actual bad debt experiences accurately, and not just made for the sake of manipulating the income and expenses reported on their financial statements. A change in the estimation method that provides a comparison of the 2018 income statement follows. In this example, net income appears higher under the balance sheet method than the income statement method: $280,000 compared to $289,750, respectively. BWW could change to the balance sheet method for estimating bad debt to give the appearance that income is greater. An investor or lender looking at BWW may consider providing funds given the earnings performance, unaware that the estimation method alone may result in an inflated income. So, what can an investor or lender do to recognize earnings management (or manipulation)? An investor or lender can compare ratio analysis to others in the industry, and year-to-year trend analysis can be helpful. The number of days’ sales in receivables ratio is a usually a good indicator of manipulation activity. A quicker collection period found in the first two years of operation can signal negative earnings behavior (as compared to industry standards). Earnings management can be a bit more difficult, given its acceptability under GAAP. As with uncovering earnings manipulation, due diligence with ratio and trend analysis is paramount. These topics will be covered in more depth in Appendix A: Financial Statement Analysis . Concepts In Practice Competitor Acquisitions As companies become large players in industry, they may consider acquiring competitors. When acquisition discussions occur, financial information, future growth channels, and business organizational structure play heavy roles in the decision process. A level of financial transparency is expected with an acquisition candidate, but during buying negotiations, each business will present the best financial position possible. The seller’s goal is to yield a high sales price; the desire to present a rosy picture could lead to earnings manipulation. An acquirer needs to be mindful of this and review trend analysis and ratio comparisons before making a purchase decision. Consider General Electric Company (GE) . GE ’s growth model in recent years was based on acquiring additional businesses within the industry. The company did not do its due diligence on several acquisitions, including Baker Hughes , and it was misled to believe the acquired businesses were in a stable financial earnings position. The acquisitions led to a declining financial position and reduced stock price. In order for GE to restructure and return to a positive growth model, it had to sell its interests in Baker Hughes and other acquisitions that were underperforming based on expectations. 9.5 Apply Revenue Recognition Principles to Long-Term Projects While most receivable reporting is straightforward when recognizing revenue and matching expenses in the same period, a few unique situations require special revenue distribution for long-term projects. Long-term construction-company projects, real estate installment sales, multi-year magazine subscriptions, and a combined equipment sale with an accompanying service contract have special reporting requirements to meet revenue recognition and matching principles. Long-term construction projects, such as construction of a major sports stadium, can take several years to complete. Typically, revenue is recognized when the earnings process is complete; however, if the construction project did not begin work immediately, this could delay recognition of revenue, and expenses accumulated during the period would be unmatched. These unmatched expenses can misstate financial statements (particularly the income statement) and mislead stakeholders. There are also tax implications, where a company may benefit from tax breaks with reduced earnings. Two methods can be applied to long-term construction projects that are consistent with the revenue recognition criteria you’ve learned about. The methods commonly utilized by construction contractors are the percentage of completion and completed contract (see Figure 9.6 ). The percentage of completion method takes the percentage of work completed for the period and divides that by the total revenues from the contract. The percentage of work completed for the period distributes the estimated total project costs over the contract term based on the actual completion amount, up to that point. The percentage can be based on such factors as percentage of anticipated final costs incurred at a given point or an engineering report that estimates the percentage of completion of the project at a stage of production. The completed contract method delays reporting of both revenues and expenses until the entire contract is complete. This can create reporting issues and is typically used only where cost and earnings cannot be reasonably estimated throughout the contract term. Unlike most residential home loan transactions (usually labeled as mortgage loans), which tend to require monthly payments, commercial real estate sales are often structured as an installment sale (see Figure 9.7 ) and usually involve periodic installment payments from buyers. These payments can be structured with annual payments, interest-only payments, or any other payment format to which the parties agree. However, a seller/lender has no guarantee that the buyer will pay the debt in its entirety. In this event, the property serves as security for the seller/lender if legal action is taken. The longer the debt remains outstanding, the higher the risk the buyer will not complete payment. With traditional accrual accounting, risk is not considered and revenue is reported immediately. The installment method accounts for risk and defers revenue using a gross profit percentage. As installment payments are made, this percentage is applied to the current period. Multi-year magazine subscriptions are long-term service contracts with payment usually occurring in advance of any provided service. The company may not recognize this revenue until the subscription has been provided, but there is also no guarantee that the contract will be honored in its entirety at the conditions expected. Financial Accounting Standards Board, Topic 606, Revenue from Contracts with Customers , requires businesses to report revenue “in an amount that reflects the consideration to which the entity expects to be entitled in exchange for the goods or services.” 6 Thus, once a change occurs to the expected revenue distribution, this new amount is recorded going forward. 6 Financial Accounting Standards Board (FASB). “Revenue from Contracts with Customers (Topic 606).” FASB Accounting Standards Update, Financial Accounting Series . April 2016. https://asc.fasb.org/imageRoot/32/79982032.pdf A combined equipment purchase with an accompanying service contract requires separate reporting of the sale and service contract. An example of this is a cell phone purchase that has a service contract (warranty) for any damage to the unit. There is no guarantee that damage will occur or that service will be provided, but the customer has purchased this policy as insurance. Thus, the company must reasonably estimate this revenue each period and distribute this estimation over the life of the service contract. Or, the company may wait until the contract expires before reporting any revenue or expenses associated with the service contract. Concepts In Practice U.S. Bank Stadium Construction HKS, Inc. received a construction contract from the Minnesota Sports Facilities Authority to build the new U.S. Bank Stadium. The construction contract services began in 2012, but the stadium was not complete until 2016. The total construction cost was approximately $1.129 billion. The portion of construction revenues earned by HKS, Inc. could not be reported upon initial receipt of funds but were instead distributed using the percentage of completion method. Much of the costs and completion associated with building the stadium occurred in the later years of the project (specifically 2015); thus, the company experienced a sharp increase in percentage of completion in the 2015 period. This showed a substantial increase to revenues during this period. IFRS Connection Revenue and Receivables When Financial Accounting Standards Board (FASB) and International Accounting Standards Board (IASB) began their joint work to create converged standards, a primary goal was to develop a single, comprehensive revenue recognition standard. At the time work began, International Financial Reporting Stands (IFRS) had one general standard that was applied to all companies with little guidance for various industries or different revenue scenarios. On the other hand, U.S. generally accepted accounting principles (GAAP) had more than 100 standards that applied to revenue recognition. Because of the global nature of business, including investing and borrowing, it was important to increase the comparability of revenue measurement and reporting. After years of work, a new standard was agreed upon; both FASB and IASB released a revenue recognition standard that is essentially the same, with only a few differences. In the United States, the new revenue recognition standards became effective for reporting in 2018 for publicly traded companies. A few differences remain in the reporting of revenue. In accounting for long-term projects, IFRS does not allow the completed contract method. If estimating the percentage of completion of the project is not possible, IFRS allows revenues equal to costs to be recognized. This results in no profit recognized in the current period, but rather all profit being deferred until the completion of the project. Receivables represent amounts owed to the business from sales or service activities that have been charged or loans that have been made to customers or others. Proper reporting of receivables is important because it affects ratios used in the analysis of a company’s solvency and liquidity, and also because reporting of receivables should reflect future cash receipts. Under both U.S. GAAP and IFRS, receivables are reported as either current or noncurrent assets depending on when they are due. Also, receivables that do not have an interest component are carried at net realizable value or the amount the company expects to receive for the receivable. This requires estimation and reporting of an allowance for uncollectible accounts (sometimes referred to as “provisions” under IFRS). However, receivables that do have a significant financing component are reported at amortized cost adjusted for an estimate of uncollectible accounts. GAAP and IFRS can differ in the financial statement presentation of receivables. GAAP requires a liquidity presentation on the balance sheet, meaning assets are listed in order of liquidity (those assets most easily converted into cash to those assets least easily converted to cash). Thus, receivables—particularly accounts receivable, which are highly liquid—are presented right after cash. However, IFRS allows reverse liquidity presentation. Therefore, receivables may appear as one of the last items in the asset section of the balance sheet under IFRS. This requires careful observance of the presentation being used when comparing a company reporting under U.S. GAAP to one using IFRS when assessing receivables. In the case of notes receivable, the method for estimating uncollectible accounts differs between U.S. GAAP and IFRS. IFRS estimates uncollectible accounts on notes receivable in a three-level process, depending upon whether the note receivable has maintained its original credit risk, increased slightly in credit risk, or increased significantly in riskiness. For companies using U.S. GAAP, estimated uncollectible accounts are based on the overall lifetime riskiness. 9.6 Explain How Notes Receivable and Accounts Receivable Differ So far, our discussion of receivables has focused solely on accounts receivable. Companies, however, can expand their business models to include more than one type of receivable. This receivable expansion allows a company to attract a more diverse clientele and increase asset potential to further grow the business. As you’ve learned, accounts receivable is typically a more informal arrangement between a company and customer that is resolved within a year and does not include interest payments. In contrast, notes receivable (an asset) is a more formal legal contract between the buyer and the company, which requires a specific payment amount at a predetermined future date. The length of contract is typically over a year, or beyond one operating cycle. There is also generally an interest requirement because the financial loan amount may be larger than accounts receivable, and the length of contract is possibly longer. A note can be requested or extended in exchange for products and services or in exchange for cash (usually in the case of a financial lender). Several characteristics of notes receivable further define the contract elements and scope of use. Key Feature Comparison of Accounts Receivable and Notes Receivable Accounts Receivable Notes Receivable An informal agreement between customer and company Receivable in less than one year or within a company’s operating cycle Does not include interest A legal contract with established payment terms Receivable beyond one year and outside of a company’s operating cycle Includes interest Table 9.2 Think It Through Dishonored Note You are the owner of a retail health food store and have several large companies with whom you do business. Many competitors in your industry are vying for your customers’ business. For each sale, you issue a notes receivable to the company, with an interest rate of 10% and a maturity date 18 months after the issue date. Each note has a minimum principal amount of $500,000. Let’s say one of these companies is unable to pay in the established timeframe and dishonors the note. What would you do? How does this dishonored note affect your company both financially and nonfinancially? If your customer wanted to renegotiate the terms of the agreement, would you agree? If so, what would be the terms? Characteristics of Notes Receivable Notes receivable have several defining characteristics that include principal, length of contract terms, and interest. The principal of a note is the initial loan amount, not including interest, requested by the customer. If a customer approaches a lender, requesting $2,000, this amount is the principal. The date on which the security agreement is initially established is the issue date . A note’s maturity date is the date at which the principal and interest become due and payable. The maturity date is established in the initial note contract. For example, when the previously mentioned customer requested the $2,000 loan on January 1, 2018, terms of repayment included a maturity date of 24 months. This means that the loan will mature in two years, and the principal and interest are due at that time. The following journal entries occur at the note’s established start date. The first entry shows a note receivable in exchange for a product or service, and the second entry illustrates the note from the point of view that a $2,000 loan was issued by a financial institution to a customer (borrower). Before realization of the maturity date, the note is accumulating interest revenue for the lender. Interest is a monetary incentive to the lender that justifies loan risk. An annual interest rate is established with the loan terms. The interest rate is the part of a loan charged to the borrower, expressed as an annual percentage of the outstanding loan amount. Interest is accrued daily, and this accumulation must be recorded periodically (each month for example). The Revenue Recognition Principle requires that the interest revenue accrued is recorded in the period when earned. Periodic interest accrued is recorded in Interest Revenue and Interest Receivable. To calculate interest, the company can use the following formulas. The following example uses months but the calculation could also be based on a 365-day year. Another common way to state the interest formula is Interest = Principal × Rate × Time. From the previous example, the company offered a $2,000 note with a maturity date of 24 months. The annual interest rate on the loan is 10%. Each period the company needs to record an entry for accumulated interest during the period. In this example, the first year’s interest revenue accumulation is computed as 10% × $2,000 × (12/12) = $200. The $200 is recognized in Interest Revenue and Interest Receivable. When interest is due at the end of the note (24 months), the company may record the collection of the loan principal and the accumulated interest. These transactions can be recorded as one entry or two. The first set of entries show collection of principal, followed by collection of the interest. Interest revenue from year one had already been recorded in 2018, but the interest revenue from 2019 is not recorded until the end of the note term. Thus, Interest Revenue is increasing (credit) by $200, the remaining revenue earned but not yet recognized. Interest Receivable decreasing (credit) reflects the 2018 interest owed from the customer that is paid to the company at the end of 2019. The second possibility is one entry recognizing principal and interest collection. If the note term does not exceed one accounting period, the entry showing note collection may not reflect interest receivable. For example, let’s say the company’s note maturity date was 12 months instead of 24 (payment in full occurs December 31, 2018). The entry to record collection of the principal and interest follows. The examples provided account for collection of the note in full on the maturity date, which is considered an honored note. But what if the customer does not pay within the specified contract length? This situation is considered a dishonored note. A lender will still pursue collection of the note but will not maintain a long-term receivable on its books. Instead, the lender will convert the notes receivable and interest due into an account receivable. Sometimes a company will classify and label the uncollected account as a Dishonored Note Receivable. Using our example, if the company was unable to collect the $2,000 from the customer at the 12-month maturity date, the following entry would occur. If it is still unable to collect, the company may consider selling the receivable to a collection agency. When this occurs, the collection agency pays the company a fraction of the note’s value, and the company would write off any difference as a factoring (third-party debt collection) expense. Let’s say that our example company turned over the $2,200 accounts receivable to a collection agency on March 5, 2019 and received only $500 for its value. The difference between $2,200 and $500 of $1,700 is the factoring expense. Notes receivable can convert to accounts receivable, as illustrated, but accounts receivable can also convert to notes receivable. The transition from accounts receivable to notes receivable can occur when a customer misses a payment on a short-term credit line for products or services. In this case, the company could extend the payment period and require interest. For example, a company may have an outstanding account receivable in the amount of $1,000. The customer negotiates with the company on June 1 for a six-month note maturity date, 12% annual interest rate, and $250 cash up front. The company records the following entry at contract establishment. This examines a note from the lender’s perspective; see Current Liabilities for an in-depth discussion on the customer’s liability with a note (payable). Illustrated Examples of Notes Receivable To illustrate notes receivable scenarios, let’s return to Billie’s Watercraft Warehouse (BWW) as the example. BWW has a customer, Waterways Corporation, that tends to have larger purchases that require an extended payment period. On January 1, 2018, Waterways purchased merchandise in the amount of $250,000. BWW agreed to lend the $250,000 purchase cost (sales price) to Waterways under the following conditions. First, BWW agrees to accept a note payable issued by Waterways. The conditions of the note are that the principal amount is $250,000, the maturity date on the note is 24 months, and the annual interest rate is 12%. On January 1, 2018, BWW records the following entry. Notes Receivable: Waterways increases (debit), and Sales Revenue increases (credit) for the principal amount of $250,000. On December 31, 2018, BWW records interest accumulated on the note for 12 months. Interest Receivable: Waterways increases (debit) as does Interest Revenue (credit) for 12 months of interest computed as $250,000 × 12% × (12/12). On December 31, 2019, Waterways Corporation honors the note; BWW records this collection as a single entry. Cash increases (debit) for the principal and interest total of $310,000, Notes Receivable: Waterways decreases (credit) for the principal amount of $250,000, Interest Receivable: Waterways decreases (credit) for the 2018 accumulated interest amount of $30,000, and Interest Revenue increases (credit) for the 2019 interest collection amount of $30,000. BWW does business with Sea Ferries Inc. BWW issued Sea Ferries a note in the amount of $100,000 on January 1, 2018, with a maturity date of six months, at a 10% annual interest rate. On July 2, BWW determined that Sea Ferries dishonored its note and recorded the following entry to convert this debt into accounts receivable. Accounts Receivable: Sea Ferries increases (debit) for the principal note amount plus interest, Notes Receivable: Sea Ferries decreases (credit) for the principal amount due, and Interest Revenue increases (credit) for interest earned at maturity. Interest is computed as $100,000 × 10% × (6/12). On September 1, 2018, BWW determines that Sea Ferries’s account will be uncollectible and sells the balance to a collection agency for a total of $35,000. Cash increases (debit) for the agreed-upon discounted value of $35,000, Factoring Expense increases (debit) for the outstanding amount and the discounted sales price, and Accounts Receivable: Sea Ferries decreases (credit) for the original amount owed. Alliance Cruises is a customer of BWW with an outstanding accounts receivable balance of $50,000. Alliance is unable to pay in full on schedule, so it negotiates with BWW on March 1 to convert its accounts receivable into a notes receivable. BWW agrees to the following terms: six-month note maturity date, 18% annual interest rate, and $10,000 cash up front. BWW records the following entry at contract establishment. Cash increases (debit) for the up-front collection of $10,000, Notes Receivable: Alliance increases (debit) for the principal amount on the note of $40,000, and Accounts Receivable: Alliance decreases (credit) for the original amount Alliance owed of $50,000. Link to Learning Another opportunity for a company to issue a notes receivable is when one business tries to acquire another. As part of an acquisition sale between MMA Capital Management LLC and Hunt Companies Inc. , MMA “provided financing for the purchase price in the form of a seven-year, note receivable from Hunt” with an interest rate of 5%, payable in quarterly installments. Read this article on the terms of sale and the role of the notes receivable in the MMA / Hunt Acquisition to learn more. 9.7 Appendix: Comprehensive Example of Bad Debt Estimation The following comprehensive example will illustrate the bad debt estimation process from the sales transaction to adjusting entry reporting for all three bad debt estimation methods: income statement, balance sheet, and balance sheet aging of receivables. Furniture Direct sells office furniture to large scale businesses. Because the purchases are typically large, Furniture Direct allows customers to pay on credit using an in-house account. At the end of the year, Furniture Direct must estimate bad debt using one of the three estimation methods. It is currently using the income statement method and estimates bad debt at 5% of credit sales. If it were to switch to the balance sheet method, it would estimate bad debt at 8% of accounts receivable. If it were to use the balance sheet aging of receivables method, it would split its receivables into three categories: 0–30 days past due at 5%, 31–90 days past due at 10%, and over 90 days past due at 20%. There is currently a zero balance, transferred from the prior year’s Allowance for Doubtful Accounts. The following information is available from the year-end income statement and balance sheet. There is also additional information regarding the distribution of accounts receivable by age. If the company were to maintain the income statement method, the total bad debt estimation would be $67,500 ($1,350,000 × 5%), and the following adjusting entry would occur. If the company were to use the balance sheet method, the total bad debt estimation would be $59,600 ($745,000 × 8%), and the following adjusting entry would occur. If the company were to use the balance sheet aging of receivables method, the total bad debt estimation would be $58,250, calculated as shown: The adjusting entry recorded using the aging method is as follows. As you can see, the methods provide different financial figures. While it is up to the company to determine which method best describes its financial position, as you see in Account for Uncollectible Accounts Using the Balance Sheet and Income Statement Approaches , a company may manage these methods and figures to present the best financial position possible. Continuing Application Grocery Store Offerings Every week, millions of shoppers visit grocery stores. Consider the various transactions that are occurring at any given time. Most of the items found within a grocery store are perishable and have a finite shelf life. The majority of purchases are paid with cash, check, or credit card. Therefore, you might assume that a grocery store would not have a balance in accounts receivable. However, grocery stores have evolved to become a one-stop shop for many items. You can now purchase gas, seasonal decorations, cooking utensils, and even fill your prescriptions at many stores.
u.s._history
Summary 24.1 Prosperity and the Production of Popular Entertainment For many middle-class Americans, the 1920s was a decade of unprecedented prosperity. Rising earnings generated more disposable income for the consumption of entertainment, leisure, and consumer goods. This new wealth coincided with and fueled technological innovations, resulting in the booming popularity of entertainments like movies, sports, and radio programs. Henry Ford’s advances in assembly-line efficiency created a truly affordable automobile, making car ownership a possibility for many Americans. Advertising became as big an industry as the manufactured goods that advertisers represented, and many families relied on new forms of credit to increase their consumption levels and strive for a new American standard of living. 24.2 Transformation and Backlash The old and the new came into sharp conflict in the 1920s. In many cases, this divide was geographic as well as philosophical; city dwellers tended to embrace the cultural changes of the era, whereas those who lived in rural towns clung to traditional norms. The Sacco and Vanzetti trial in Massachusetts, as well as the Scopes trial in Tennessee, revealed many Americans’ fears and suspicions about immigrants, radical politics, and the ways in which new scientific theories might challenge traditional Christian beliefs. Some reacted more zealously than others, leading to the inception of nativist and fundamentalist philosophies, and the rise of terror groups such as the Second Ku Klux Klan. 24.3 A New Generation Different groups reacted to the upheavals of the 1920s in different ways. Some people, especially young urbanites, embraced the new amusements and social venues of the decade. Women found new opportunities for professional and political advancement, as well as new models of sexual liberation; however, the women’s rights movement began to wane with the passage of the Nineteenth Amendment. For Black artists of the Harlem Renaissance, the decade was marked less by leisure and consumption than by creativity and purpose. African American leaders like Marcus Garvey and W. E. B. Du Bois responded to the retrenched racism of the time with different campaigns for civil rights and Black empowerment. Others, like the writers of the Lost Generation, reveled in exposing the hypocrisies and shallowness of mainstream middle-class culture. Meanwhile, the passage of prohibition served to increase the illegal production of alcohol and led to a rise in organized crime. 24.4 Republican Ascendancy: Politics in the 1920s After World War I, Americans were ready for “a return to normalcy,” and Republican Warren Harding offered them just that. Under the guidance of his big-business backers, Harding’s policies supported businesses at home and isolation from foreign affairs. His administration was wracked by scandals, and after he died in 1923, Calvin Coolidge continued his policy legacy in much the same vein. Herbert Hoover, elected as Coolidge’s heir apparent, planned for more of the same until the stock market crash ended a decade of Republican ascendancy.
Chapter Outline 24.1 Prosperity and the Production of Popular Entertainment 24.2 Transformation and Backlash 24.3 A New Generation 24.4 Republican Ascendancy: Politics in the 1920s Introduction Following the hardships of the immediate postwar era, the United States embarked upon one of the most prosperous decades in history. Mass production, especially of the automobile, increased mobility and fostered new industries. Unemployment plummeted as businesses grew to meet this increased demand. Cities continued to grow and, according to the 1920 census, a majority of the population lived in urban areas of twenty-five hundred or more residents. Jazz music, movies, speakeasies, and new dances dominated the urban evening scene. Recent immigrants from southern and eastern Europe, many of them Catholic, now participated in the political system. This challenged rural Protestant fundamentalism, even as quota laws sought to limit new immigration patterns. The Ku Klux Klan rose to greater power, as they protested not only the changing role of African Americans but also the growing population of immigrant, Catholic, and Jewish Americans. This mixture of social, political, economic, and cultural change and conflict gave the decade the nickname the “Roaring Twenties” or the “Jazz Age.” The above illustration ( Figure 24.1 ), which graced the cover of F. Scott Fitzgerald’s Tales of the Jazz Age , embodies the popular view of the 1920s as a nonstop party, replete with dancing, music, flappers, and illegal drinking.
[ { "answer": { "ans_choice": 2, "ans_text": "C" }, "bloom": null, "hl_context": "<hl> In 1927 , the world of the silent movie began to wane with the New York release of the first “ talkie ” : The Jazz Singer . <hl> The plot of this film , which starred Al Jolson , told a distinctively American story of the 1920s . It follows the life of a Jewish man from his boyhood days of being groomed to be the cantor at the local synagogue to his life as a famous and “ Americanized ” jazz singer . Both the story and the new sound technology used to present it were popular with audiences around the country . <hl> It quickly became a huge hit for Warner Brothers , one of the “ big five ” motion picture studios in Hollywood along with Twentieth Century Fox , RKO Pictures , Paramount Pictures , and Metro-Goldwyn-Mayer . <hl>", "hl_sentences": "In 1927 , the world of the silent movie began to wane with the New York release of the first “ talkie ” : The Jazz Singer . It quickly became a huge hit for Warner Brothers , one of the “ big five ” motion picture studios in Hollywood along with Twentieth Century Fox , RKO Pictures , Paramount Pictures , and Metro-Goldwyn-Mayer .", "question": { "cloze_format": "___ was released in 1927 was the first successful talking motion picture.", "normal_format": "Which of the following films released in 1927 was the first successful talking motion picture?", "question_choices": [ "The Clansman", "The Great Gatsby", "The Jazz Singer", "The Birth of a Nation" ], "question_id": "fs-idm65978752", "question_text": "Which of the following films released in 1927 was the first successful talking motion picture?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 0, "ans_text": "radios" }, "bloom": null, "hl_context": "<hl> Radio also transformed how Americans enjoyed sports . <hl> <hl> The introduction of play-by-play descriptions of sporting events broadcast over the radio brought sports entertainment right into the homes of millions . <hl> <hl> Radio also helped to popularize sports figures and their accomplishments . <hl> Jim Thorpe , who grew up in the Sac and Fox Nation in Oklahoma , was known as one of the best athletes in the world : He medaled in the 1912 Olympic Games , played Major League Baseball , and was one of the founding members of the National Football League . Other sports superstars were soon household names . In 1926 , Gertrude Ederle became the first woman to swim the English Channel . Helen Wills dominated women ’ s tennis , winning Wimbledon eight times in the late 1920s ( Figure 24.8 ) , whereas “ Big Bill ” Tilden won the national singles title every year from 1920 to 1925 . In football , Harold “ Red ” Grange played for the University of Illinois , averaging over ten yards per carry during his college career . The biggest star of all was the “ Sultan of Swat , ” Babe Ruth , who became America ’ s first baseball hero ( Figure 24.8 ) . He changed the game of baseball from a low-scoring one dominated by pitchers to one where his hitting became famous . By 1923 , pitchers frequently chose to intentionally walk him . In 1927 , he hit sixty home runs . 24.2 Transformation and Backlash Learning Objectives By the end of this section , you will be able to : <hl> The power of radio further sped up the processes of nationalization and homogenization that were previously begun with the wide distribution of newspapers made possible by railroads and telegraphs . <hl> Far more effectively than these print media , however , radio created and pumped out American culture onto the airwaves and into the homes of families around the country . Syndicated radio programs like Amos ‘ n ’ Andy , which began in the late 1920s , entertained listeners around the country — in the case of the popular Amos ‘ n ’ Andy , it did so with racial stereotypes about African Americans familiar from minstrel shows of the previous century . No longer were small corners of the country separated by their access to information . With the radio , Americans from coast to coast could listen to exactly the same programming . <hl> This had the effect of smoothing out regional differences in dialect , language , music , and even consumer taste . <hl>", "hl_sentences": "Radio also transformed how Americans enjoyed sports . The introduction of play-by-play descriptions of sporting events broadcast over the radio brought sports entertainment right into the homes of millions . Radio also helped to popularize sports figures and their accomplishments . The power of radio further sped up the processes of nationalization and homogenization that were previously begun with the wide distribution of newspapers made possible by railroads and telegraphs . This had the effect of smoothing out regional differences in dialect , language , music , and even consumer taste .", "question": { "cloze_format": "The popularization of ________ expanded the communications and sports industries.", "normal_format": "Which popularization expanded the communications and sports industries?", "question_choices": [ "radios", "talkies", "the Model T", "airplanes" ], "question_id": "fs-idm185646032", "question_text": "The popularization of ________ expanded the communications and sports industries." }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 3, "ans_text": "D" }, "bloom": null, "hl_context": "The 1920s not only witnessed a transformation in ground transportation but also major changes in air travel . By the mid - 1920s , men — as well as some pioneering women like the African American stunt pilot Bessie Coleman ( Figure 24.6 ) — had been flying for two decades . But there remained doubts about the suitability of airplanes for long-distance travel . <hl> Orville Wright , one of the pioneers of airplane technology in the United States , once famously declared , “ No flying machine will ever fly from New York to Paris [ because ] no known motor can run at the requisite speed for four days without stopping . ” However , in 1927 , this skepticism was finally put to rest when Charles Lindbergh became the first person to fly solo across the Atlantic Ocean , flying from New York to Paris in thirty-three hours ( Figure 24.6 ) . <hl>", "hl_sentences": "Orville Wright , one of the pioneers of airplane technology in the United States , once famously declared , “ No flying machine will ever fly from New York to Paris [ because ] no known motor can run at the requisite speed for four days without stopping . ” However , in 1927 , this skepticism was finally put to rest when Charles Lindbergh became the first person to fly solo across the Atlantic Ocean , flying from New York to Paris in thirty-three hours ( Figure 24.6 ) .", "question": { "cloze_format": "___ was the first person to fly solo across the Atlantic Ocean.", "normal_format": "Who was the first person to fly solo across the Atlantic Ocean?", "question_choices": [ "Orville Wright", "Jim Thorpe", "Charlie Chaplin", "Charles Lindbergh" ], "question_id": "fs-idm242162400", "question_text": "Who was the first person to fly solo across the Atlantic Ocean?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 1, "ans_text": "B" }, "bloom": null, "hl_context": "The American Civil Liberties Union ( ACLU ) hoped to challenge the Butler Act as an infringement of the freedom of speech . As a defendant , the ACLU enlisted teacher and coach John Scopes , who suggested that he may have taught evolution while substituting for an ill biology teacher . Town leaders in Dayton , Tennessee , for their part , sensed an opportunity to promote their town , which had lost more than one-third of its population , and welcomed the ACLU to stage a test case against the Butler Act . <hl> The ACLU and the town got their wish as the Scopes Monkey Trial , as the newspapers publicized it , quickly turned into a carnival that captured the attention of the country and epitomized the nation ’ s urban / rural divide ( Figure 24.12 ) . <hl> In this urban / rural conflict , Tennessee lawmakers drew a battle line over the issue of evolution and its contradiction of the accepted , biblical explanation of history . Charles Darwin had first published his theory of natural selection in 1859 , and by the 1920s , many standard textbooks contained information about Darwin ’ s theory of evolution . Fundamentalist Protestants targeted evolution as representative of all that was wrong with urban society . <hl> Tennessee ’ s Butler Act made it illegal “ to teach any theory that denies the story of the Divine Creation of man as taught in the Bible , and to teach instead that man has descended from a lower order of animals . ” <hl>", "hl_sentences": "The ACLU and the town got their wish as the Scopes Monkey Trial , as the newspapers publicized it , quickly turned into a carnival that captured the attention of the country and epitomized the nation ’ s urban / rural divide ( Figure 24.12 ) . Tennessee ’ s Butler Act made it illegal “ to teach any theory that denies the story of the Divine Creation of man as taught in the Bible , and to teach instead that man has descended from a lower order of animals . ”", "question": { "cloze_format": "The Scopes Monkey Trial revolved around a law that banned teaching about ________ in public schools.", "normal_format": "The Scopes Monkey Trial revolved around a law that banned teaching about what in public schools?", "question_choices": [ "the Bible", "Darwinism", "primates", "Protestantism" ], "question_id": "fs-idp101056", "question_text": "The Scopes Monkey Trial revolved around a law that banned teaching about ________ in public schools." }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 3, "ans_text": "Billy Sunday" }, "bloom": null, "hl_context": "Indicative of the revival of Protestant fundamentalism and the rejection of evolution among rural and White Americans was the rise of Billy Sunday . <hl> As a young man , Sunday had gained fame as a baseball player with exceptional skill and speed . <hl> <hl> Later , he found even more celebrity as the nation ’ s most revered evangelist , drawing huge crowds at camp meetings around the country . <hl> He was one of the most influential evangelists of the time and had access to some of the wealthiest and most powerful families in the country ( Figure 24.13 ) . Sunday rallied many Americans around “ old-time ” fundamentalist religion and garnered support for prohibition . Recognizing Sunday ’ s popular appeal , Bryan attempted to bring him to Dayton for the Scopes trial , although Sunday politely refused .", "hl_sentences": "As a young man , Sunday had gained fame as a baseball player with exceptional skill and speed . Later , he found even more celebrity as the nation ’ s most revered evangelist , drawing huge crowds at camp meetings around the country .", "question": { "cloze_format": "___ was both a professional baseball player and an influential evangelist during the 1920s.", "normal_format": "Which man was both a professional baseball player and an influential evangelist during the 1920s?", "question_choices": [ "Babe Ruth", "H. L. Mencken", "Jim Thorpe", "Billy Sunday" ], "question_id": "fs-idp433152", "question_text": "Which man was both a professional baseball player and an influential evangelist during the 1920s?" }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 0, "ans_text": "Sigmund Freud" }, "bloom": null, "hl_context": "<hl> As men and women pushed social and cultural boundaries in the Jazz Age , sexual mores changed and social customs grew more permissive . <hl> <hl> “ Petting parties ” or “ necking parties ” became the rage on college campuses . <hl> <hl> Psychologist Sigmund Freud and British “ sexologist ” Havelock Ellis emphasized that sex was a natural and pleasurable part of the human experience . <hl> Margaret Sanger , the founder of Planned Parenthood , launched an information campaign on birth control to give women a choice in the realm in which suffrage had changed little — the family . The popularization of contraception and the private space that the automobile offered to teenagers and unwed couples also contributed to changes in sexual behavior . Many Americans were disillusioned in the post-World War I era , and their reactions took many forms . <hl> Rebellious American youth , in particular , adjusted to the changes by embracing a new morality that was far more permissive than the social mores of their parents . <hl> Many young women of the era shed their mother ’ s morality and adopted the dress and mannerisms of a flapper , the Jazz Age female stereotype , seeking the endless party . Flappers wore shorter skirts , shorter hair , and more makeup , and they drank and smoked with the boys ( Figure 24.14 ) . Flappers ’ dresses emphasized straight lines from the shoulders to the knees , minimizing breasts and curves while highlighting legs and ankles . The male equivalent of a flapper was a “ sheik , ” although that term has not remained as strong in the American vernacular . At the time , however , many of these fads became a type of conformity , especially among college-aged youths , with the signature bob haircut of the flapper becoming almost universal — in both the United States and overseas . The 1920s was a time of dramatic change in the United States . <hl> Many young people , especially those living in big cities , embraced a new morality that was much more permissive than that of previous generations . <hl> They listened to jazz music , especially in the nightclubs of Harlem . Although prohibition outlawed alcohol , criminal bootlegging and importing businesses thrived . The decade was not a pleasure cruise for everyone , however ; in the wake of the Great War , many were left awaiting the promise of a new generation .", "hl_sentences": "As men and women pushed social and cultural boundaries in the Jazz Age , sexual mores changed and social customs grew more permissive . “ Petting parties ” or “ necking parties ” became the rage on college campuses . Psychologist Sigmund Freud and British “ sexologist ” Havelock Ellis emphasized that sex was a natural and pleasurable part of the human experience . Rebellious American youth , in particular , adjusted to the changes by embracing a new morality that was far more permissive than the social mores of their parents . Many young people , especially those living in big cities , embraced a new morality that was much more permissive than that of previous generations .", "question": { "cloze_format": "___ ideas encouraged the new morality of the 1920s.", "normal_format": "The popularization of which psychologist’s ideas encouraged the new morality of the 1920s?", "question_choices": [ "Sigmund Freud", "Alice Paul", "W. E. B. Du Bois", "Margaret Sanger" ], "question_id": "fs-idm16581968", "question_text": "The popularization of which psychologist’s ideas encouraged the new morality of the 1920s?" }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 1, "ans_text": "B" }, "bloom": null, "hl_context": "Nor did the struggle for women ’ s rights through the promotion and passage of legislation cease in the 1920s . In 1921 , Congress passed the Promotion of the Welfare and Hygiene of Maternity and Infancy Act , also known as the Sheppard-Towner Act , which earmarked $ 1.25 million for well-baby clinics and educational programs , as well as nursing . This funding dramatically reduced the rate of infant mortality . <hl> Two years later , in 1923 , Alice Paul drafted and promoted an Equal Rights Amendment ( ERA ) that promised to end all sex discrimination by guaranteeing that “ Men and women shall have equal rights throughout the United States and every place subject to its jurisdiction . ” <hl>", "hl_sentences": "Two years later , in 1923 , Alice Paul drafted and promoted an Equal Rights Amendment ( ERA ) that promised to end all sex discrimination by guaranteeing that “ Men and women shall have equal rights throughout the United States and every place subject to its jurisdiction . ”", "question": { "cloze_format": "___ did Alice Paul promote to end gender discrimination.", "normal_format": "Which amendment did Alice Paul promote to end gender discrimination?", "question_choices": [ "Prohibition Amendment", "Equal Rights Amendment", "Sheppard-Towner Amendment", "Free Exercise Amendment" ], "question_id": "fs-idm11693216", "question_text": "Which amendment did Alice Paul promote to end gender discrimination?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 3, "ans_text": "Babbitt" }, "bloom": null, "hl_context": "Not all Lost Generation writers were like Fitzgerald or Hemingway . The writing of Sinclair Lewis , rather than expressing a defined disillusionment , was more influenced by the Progressivism of the previous generation . <hl> In Babbitt ( 1922 ) , he examined the “ sheep following the herd ” mentality that conformity promoted . <hl> <hl> He satirized American middle-class life as pleasure seeking and mindless . <hl> Similarly , writer Edith Wharton celebrated life in old New York , a vanished society , in The Age of Innocence , in 1920 . Wharton came from a very wealthy , socialite family in New York , where she was educated by tutors and never attended college . She lived for many years in Europe ; during the Great War , she worked in Paris helping women establish businesses . 24.4 Republican Ascendancy : Politics in the 1920s Learning Objectives By the end of this section , you will be able to :", "hl_sentences": "In Babbitt ( 1922 ) , he examined the “ sheep following the herd ” mentality that conformity promoted . He satirized American middle-class life as pleasure seeking and mindless .", "question": { "cloze_format": "___ satirized the conformity of the American middle class.", "normal_format": "Which novel of the era satirized the conformity of the American middle class?", "question_choices": [ "This Side of Paradise", "The Sun Also Rises", "A Farewell to Arms", "Babbitt" ], "question_id": "fs-idm172976", "question_text": "Which novel of the era satirized the conformity of the American middle class?" }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 2, "ans_text": "C" }, "bloom": null, "hl_context": "<hl> In the election of 1920 , professional Republicans were eager to nominate a man whom they could manage and control . <hl> <hl> Warren G . Harding , a senator from Ohio , represented just such a man ( Figure 24.20 ) . <hl> Before his nomination , Harding stated , “ America ’ s present need is not heroics but healing ; not nostrums but normalcy ; not revolution but restoration . ” Harding was genial and affable , but not everyone appreciated his speeches ; Democratic presidential-hopeful William Gibbs McAdoo described Harding ’ s speeches as “ an army of pompous phrases moving across the landscape in search of an idea . ” H . L . Mencken , the great social critic of the 1920s , wrote of Harding ’ s speaking , “ It drags itself out of the dark abysm of pish , and crawls insanely up to the top-most pinnacle of posh . It is rumble and bumble . It is flap and doodle . It is balder and dash . ”", "hl_sentences": "In the election of 1920 , professional Republicans were eager to nominate a man whom they could manage and control . Warren G . Harding , a senator from Ohio , represented just such a man ( Figure 24.20 ) .", "question": { "cloze_format": "___ was the Republican presidential nominee for the 1920 election.", "normal_format": "Who was the Republican presidential nominee for the 1920 election?", "question_choices": [ "Calvin Coolidge", "Woodrow Wilson", "Warren Harding", "James Cox" ], "question_id": "fs-idm2921312", "question_text": "Who was the Republican presidential nominee for the 1920 election?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 0, "ans_text": "Secretary of the Interior" }, "bloom": null, "hl_context": "The scandals mounted quickly . <hl> From 1920 to 1923 , Secretary of the Interior Albert B . <hl> <hl> Fall was involved in a scam that became known as the Teapot Dome scandal . <hl> <hl> Fall had leased navy reserves in Teapot Dome , Wyoming , and two other sites in California to private oil companies without opening the bidding to other companies . <hl> <hl> In exchange , the companies gave him $ 300,000 in cash and bonds , as well as a herd of cattle for his ranch . <hl> <hl> Fall was convicted of accepting bribes from the oil companies ; he was fined $ 100,000 and sentenced to a year in prison . <hl> It was the first time that a cabinet official had received such a sentence .", "hl_sentences": "From 1920 to 1923 , Secretary of the Interior Albert B . Fall was involved in a scam that became known as the Teapot Dome scandal . Fall had leased navy reserves in Teapot Dome , Wyoming , and two other sites in California to private oil companies without opening the bidding to other companies . In exchange , the companies gave him $ 300,000 in cash and bonds , as well as a herd of cattle for his ranch . Fall was convicted of accepting bribes from the oil companies ; he was fined $ 100,000 and sentenced to a year in prison .", "question": { "cloze_format": "In 1929, Albert Fall was convicted of bribery while holding the position of ________.", "normal_format": "In 1929, Albert Fall was convicted of bribery while holding the position of what? ", "question_choices": [ "Secretary of the Interior", "head of the Veterans’ Bureau", "Secretary of the Treasury", "Secretary of Commerce" ], "question_id": "fs-idm4560656", "question_text": "In 1929, Albert Fall was convicted of bribery while holding the position of ________." }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 1, "ans_text": "B" }, "bloom": null, "hl_context": "<hl> Thus , silence and inactivity became the dominant characteristics of the Coolidge presidency . <hl> Coolidge ’ s legendary reserve was famous in Washington society . Contemporaries told a possibly apocryphal story of how , at a dinner party at the White House , a woman bet her friends that she could get Coolidge to say more than three words . He looked at her and said , “ you lose . ”", "hl_sentences": "Thus , silence and inactivity became the dominant characteristics of the Coolidge presidency .", "question": { "cloze_format": "Coolidge’s presidency was characterized by ________.", "normal_format": "Which characterization Coolidge’s presidency was known for? ", "question_choices": [ "scandal and dishonesty", "silence and inactivity", "flamboyancy and extravagance", "ambition and greed" ], "question_id": "fs-idm3856768", "question_text": "Coolidge’s presidency was characterized by ________." }, "references_are_paraphrase": null } ]
24
24.1 Prosperity and the Production of Popular Entertainment Learning Objectives By the end of this section, you will be able to: Discuss the role of movies in the evolution of American culture Explain the rise of sports as a dominant social force Analyze the ways in which the automobile, especially the Model T, transformed American life In the 1920s, prosperity manifested itself in many forms, most notably in advancements in entertainment and technology that led to new patterns of leisure and consumption. Movies and sports became increasingly popular and buying on credit or “carrying” the debt allowed for the sale of more consumer goods and put automobiles within reach of average Americans. Advertising became a central institution in this new consumer economy, and commercial radio and magazines turned athletes and actors into national icons. MOVIES The increased prosperity of the 1920s gave many Americans more disposable income to spend on entertainment. As the popularity of “moving pictures” grew in the early part of the decade, “movie palaces,” capable of seating thousands, sprang up in major cities. A ticket for a double feature and a live show cost twenty-five cents; for a quarter, Americans could escape from their problems and lose themselves in another era or world. People of all ages attended the movies with far more regularity than today, often going more than once per week. By the end of the decade, weekly movie attendance swelled to ninety million people. The silent movies of the early 1920s gave rise to the first generation of movie stars. Rudolph Valentino, the lothario with the bedroom eyes, and Clara Bow, the “It Girl” with sex appeal, filled the imagination of millions of American moviegoers. However, no star captured the attention of the American viewing public more than Charlie Chaplin. This sad-eyed tramp with a moustache, baggy pants, and a cane was the top box office attraction of his time ( Figure 24.3 ). In 1927, the world of the silent movie began to wane with the New York release of the first “talkie”: The Jazz Singer . The plot of this film, which starred Al Jolson, told a distinctively American story of the 1920s. It follows the life of a Jewish man from his boyhood days of being groomed to be the cantor at the local synagogue to his life as a famous and “Americanized” jazz singer. Both the story and the new sound technology used to present it were popular with audiences around the country. It quickly became a huge hit for Warner Brothers, one of the “big five” motion picture studios in Hollywood along with Twentieth Century Fox, RKO Pictures, Paramount Pictures, and Metro-Goldwyn-Mayer. Southern California in the 1920s, however, had only recently become the center of the American film industry. Film production was originally based in and around New York, where Thomas Edison first debuted the kinetoscope in 1893. But in the 1910s, as major filmmakers like D. W. Griffith looked to escape the cost of Edison’s patents on camera equipment, this began to change. When Griffith filmed In Old California (1910), the first movie ever shot in Hollywood , California, the small town north of Los Angeles was little more than a village. As moviemakers flocked to southern California, not least because of its favorable climate and predictable sunshine, Hollywood swelled with moviemaking activity. By the 1920s, the once-sleepy village was home to a majorly profitable innovative industry in the United States. AUTOMOBILES AND AIRPLANES: AMERICANS ON THE MOVE Cinema was not the only major industry to make great technological strides in this decade. The 1920s opened up new possibilities of mobility for a large percentage of the U.S. population, as automobile manufacturers began to mass produce what had once been a luxury item, and daring aviators both demonstrated and drove advancements in aircraft technology. The most significant innovation of this era was Henry Ford’s Model T Ford, which made car ownership available to the average American. Ford did not invent the automobile—the Duryea brothers in Massachusetts as well as Gottlieb W. Daimler and Karl Friedrich Benz in Germany were early pioneers. By the early twentieth century, hundreds of car manufacturers existed. However, they all made products that were too expensive for most Americans. Ford’s innovation lay in his focus on using mass production to manufacture automobiles; he revolutionized industrial work by perfecting the assembly line, which enabled him to lower the Model T’s price from $850 in 1908 to $300 in 1924, making car ownership a real possibility for a large share of the population ( Figure 24.4 ). As prices dropped, more and more people could afford to own a car. Soon, people could buy used Model Ts for as little as five dollars, allowing students and others with low incomes to enjoy the freedom and mobility of car ownership. By 1929, there were over twenty-three million automobiles on American roads. The assembly line helped Ford reduce labor costs within the production process by moving the product from one team of workers to the next, each of them completing a step so simple they had to be, in Ford’s words, “no smarter than an ox” ( Figure 24.5 ). Ford’s reliance on the moving assembly line , scientific management, and time-motion studies added to his emphasis on efficiency over craftsmanship. Ford’s emphasis on cheap mass production brought both benefits and disadvantages to its workers. Ford would not allow his workers to unionize, and the boring, repetitive nature of the assembly line work generated a high turnover rate. However, to reduce the turnover rate, he doubled workers’ pay to five dollars a day and standardized the workday to eight hours (a reduction from the norm). Ford’s assembly line also offered greater equality than most opportunities of the time, as he paid White and Black workers equally. Seeking these wages, many African Americans from the South moved to Detroit and other large northern cities to work in factories. The automobile changed the face of America, both economically and socially. Industries like glass, steel, and rubber processing expanded to keep up with auto production. The oil industry in California, Oklahoma, and Texas expanded, as Americans’ reliance on oil increased and the nation transitioned from a coal-based economy to one driven by petroleum. The need for public roadways required local and state governments to fund a dramatic expansion of infrastructure, which permitted motels and restaurants to spring up and offer new services to millions of newly mobile Americans with cash to spend. With this new infrastructure, new shopping and living patterns emerged, and streetcar suburbs gave way to automobile suburbs as private automobile traffic on public roads began to replace mass transit on trains and trolleys. The 1920s not only witnessed a transformation in ground transportation but also major changes in air travel. By the mid-1920s, men—as well as some pioneering women like the African American stunt pilot Bessie Coleman ( Figure 24.6 )—had been flying for two decades. But there remained doubts about the suitability of airplanes for long-distance travel. Orville Wright, one of the pioneers of airplane technology in the United States, once famously declared, “No flying machine will ever fly from New York to Paris [because] no known motor can run at the requisite speed for four days without stopping.” However, in 1927, this skepticism was finally put to rest when Charles Lindbergh became the first person to fly solo across the Atlantic Ocean, flying from New York to Paris in thirty-three hours ( Figure 24.6 ). Lindbergh’s flight made him an international hero: the best-known American in the world. On his return, Americans greeted him with a ticker-tape parade—a celebration in which shredded paper thrown from surrounding buildings creates a festive, flurry effect. His flight, which he completed in the monoplane Spirit of St. Louis , seemed like a triumph of individualism in modern mass society and exemplified Americans’ ability to conquer the air with new technology. Following his success, the small airline industry began to blossom, fully coming into its own in the 1930s, as companies like Boeing and Ford developed airplanes designed specifically for passenger air transport. As technologies in engine and passenger compartment design improved, air travel became more popular. In 1934, the number of U.S. domestic air passengers was just over 450,000 annually. By the end of the decade, that number had increased to nearly two million. Technological innovation influenced more than just transportation. As access to electricity became more common and the electric motor was made more efficient, inventors began to churn out new and more complex household appliances. Newly developed innovations like radios, phonographs, vacuum cleaners, washing machines, and refrigerators emerged on the market during this period. While expensive, new consumer-purchasing innovations like store credit and installment plans made them available to a larger segment of the population. Many of these devices promised to give women—who continued to have primary responsibility for housework—more opportunities to step out of the home and expand their horizons. Ironically, however, these labor-saving devices tended to increase the workload for women by raising the standards of domestic work. With the aid of these tools, women ended up cleaning more frequently, washing more often, and cooking more elaborate meals rather than gaining spare time. Despite the fact that the promise of more leisure time went largely unfulfilled, the lure of technology as the gateway to a more relaxed lifestyle endured. This enduring dream was a testament to the influence of another growing industry: advertising. The mass consumption of cars, household appliances, ready-to-wear clothing, and processed foods depended heavily on the work of advertisers. Magazines like Ladies’ Home Journal and The Saturday Evening Post became vehicles to connect advertisers with middle-class consumers. Colorful and occasionally provocative print advertisements decorated the pages of these publications and became a staple in American popular culture ( Figure 24.7 ). The form of the advertisements, however, was not new. These colorful print ads were merely the modern incarnations of an advertising strategy that went back to the nineteenth century. The new medium for advertisers in the 1920s, the one that would reach out to consumers in radically new and innovative ways, was radio. THE POWER OF RADIO AND THE WORLD OF SPORTS After being introduced during World War I, radios became a common feature in American homes of the 1920s. Hundreds of radio stations popped up over the decade. These stations developed and broadcasted news, serial stories, and political speeches. Much like print media, advertising space was interspersed with entertainment. Yet, unlike magazines and newspapers, advertisers did not have to depend on the active participation of consumers: Advertisers could reach out to anyone within listening distance of the radio. On the other hand, their broader audience meant that they had to be more conservative and careful not to offend anyone. The power of radio further sped up the processes of nationalization and homogenization that were previously begun with the wide distribution of newspapers made possible by railroads and telegraphs. Far more effectively than these print media, however, radio created and pumped out American culture onto the airwaves and into the homes of families around the country. Syndicated radio programs like Amos ‘n’ Andy , which began in the late 1920s, entertained listeners around the country—in the case of the popular Amos ‘n’ Andy , it did so with racial stereotypes about African Americans familiar from minstrel shows of the previous century. No longer were small corners of the country separated by their access to information. With the radio, Americans from coast to coast could listen to exactly the same programming. This had the effect of smoothing out regional differences in dialect, language, music, and even consumer taste. Radio also transformed how Americans enjoyed sports. The introduction of play-by-play descriptions of sporting events broadcast over the radio brought sports entertainment right into the homes of millions. Radio also helped to popularize sports figures and their accomplishments. Jim Thorpe, who grew up in the Sac and Fox Nation in Oklahoma, was known as one of the best athletes in the world: He medaled in the 1912 Olympic Games, played Major League Baseball, and was one of the founding members of the National Football League. Other sports superstars were soon household names. In 1926, Gertrude Ederle became the first woman to swim the English Channel. Helen Wills dominated women’s tennis, winning Wimbledon eight times in the late 1920s ( Figure 24.8 ), whereas “Big Bill” Tilden won the national singles title every year from 1920 to 1925. In football, Harold “Red” Grange played for the University of Illinois, averaging over ten yards per carry during his college career. The biggest star of all was the “Sultan of Swat,” Babe Ruth, who became America’s first baseball hero ( Figure 24.8 ). He changed the game of baseball from a low-scoring one dominated by pitchers to one where his hitting became famous. By 1923, pitchers frequently chose to intentionally walk him. In 1927, he hit sixty home runs. 24.2 Transformation and Backlash Learning Objectives By the end of this section, you will be able to: Define nativism and analyze the ways in which it affected the politics and society of the 1920s Describe the conflict between urban Americans and rural fundamentalists Explain the issues in question in the Scopes trial While prosperous, middle-class Americans found much to celebrate about the new era of leisure and consumption, many Americans—often those in rural areas—disagreed on the meaning of a “good life” and how to achieve it. They reacted to the rapid social changes of modern urban society with a vigorous defense of religious values and a fearful rejection of cultural diversity and equality. NATIVISM Beginning at the end of the nineteenth century, immigration into the United States rocketed to never-before-seen heights. Many of these new immigrants were coming from eastern and southern Europe and, for many English-speaking, native-born Americans of northern European descent, the growing diversity of new languages, customs, and religions triggered anxiety and racial animosity. In reaction, some embraced nativism , prizing White Americans with older family trees over more recent immigrants, and rejecting outside influences in favor of their own local customs. Nativists also stoked a sense of fear over the perceived foreign threat, pointing to the anarchist assassinations of the Spanish prime minister in 1897, the Italian king in 1900, and even President William McKinley in 1901 as proof. Following the Bolshevik Revolution in Russia in November 1917, the sense of an inevitable foreign or communist threat only grew among those already predisposed to distrust immigrants. The sense of fear and anxiety over the rising tide of immigration came to a head with the trial of Nicola Sacco and Bartolomeo Vanzetti ( Figure 24.9 ). Sacco and Vanzetti were Italian immigrants who were accused of being part of a robbery and murder in Braintree, Massachusetts, in 1920. There was no direct evidence linking them to the crime, but (in addition to being immigrants) both men were anarchists who favored the destruction of the American market-based, capitalistic society through violence. At their trial, the district attorney emphasized Sacco and Vanzetti’s radical views, and the jury found them guilty on July 14, 1921. Despite subsequent motions and appeals based on ballistics testing, recanted testimony, and an ex-convict’s confession, both men were executed on August 23, 1927. Opinions on the trial and judgment tended to divide along nativist-immigrant lines, with immigrants supporting the innocence of the condemned pair. The verdict sparked protests from Italian and other immigrant groups, as well as from noted intellectuals such as writer John Dos Passos, satirist Dorothy Parker, and famed physicist Albert Einstein. Muckraker Upton Sinclair based his indictment of the American justice system, the “documentary novel” Boston , on Sacco and Vanzetti’s trial, which he considered a gross miscarriage of justice. As the execution neared, the radical labor union Industrial Workers of the World called for a three-day nationwide walkout, leading to the Great Colorado Coal Strike of 1927. Protests occurred worldwide from Tokyo to Buenos Aires to London ( Figure 24.9 ). One of the most articulate critics of the trial was then-Harvard Law School professor Felix Frankfurter, who would go on to be appointed to the U.S. Supreme Court by Franklin D. Roosevelt in 1939. In 1927, six years after the trial, he wrote in The Atlantic , “By systematic exploitation of the defendants’ alien blood, their imperfect knowledge of English, their unpopular social views, and their opposition to the war, the District Attorney invoked against them a riot of political passion and patriotic sentiment; and the trial judge connived at—one had almost written, cooperated in—the process.” To “preserve the ideal of American homogeneity,” the Emergency Immigration Act of 1921 introduced numerical limits on European immigration for the first time in U.S. history. These limits were based on a quota system that restricted annual immigration from any given country to 3 percent of the residents from that same country as counted in the 1910 census. The National Origins Act of 1924 went even further, lowering the level to 2 percent of the 1890 census, significantly reducing the share of eligible southern and eastern Europeans, since they had only begun to arrive in the United States in large numbers in the 1890s. Although New York congressmen Fiorello LaGuardia and Emanuel Celler spoke out against the act, there was minimal opposition in Congress, and both labor unions and the Ku Klux Klan supported the bill. When President Coolidge signed it into law, he declared, “America must be kept American.” THE KU KLUX KLAN The concern that a White, Protestant, Anglo-Saxon United States was under siege by throngs of undesirables was not exclusively directed at foreigners. The sense that the country was also facing a threat from within its borders and its own citizenry was also prevalent. This sense was clearly reflected in the popularity of the 1915 motion picture, D. W. Griffith’s The Birth of a Nation ( Figure 24.10 ). Based on The Clansman , a 1915 novel by Thomas Dixon, the film offers a racist, White-centric view of the Reconstruction Era. The film depicts noble White southerners made helpless by northern carpetbaggers who empower freed Black people to abuse White men and violate women. The heroes of the film were the Ku Klux Klan, who saved the Whites, the South, and the nation. While the film was reviled by many African Americans and the NAACP for its historical inaccuracies and its maligning of freed people, it was celebrated by many Whites who accepted the historical revisionism as an accurate portrayal of Reconstruction Era oppression. After viewing the film, President Wilson reportedly remarked, “It is like writing history with lightning, and my only regret is that it is all so terribly true.” Defining American Artistic License and the Censor In a letter dated April 17, 1915, Mary Childs Nerney, a secretary of the NAACP, wrote to a local censor to request that certain scenes be cut from The Birth of a Nation . My dear Mr. Packard: I am utterly disgusted with the situation in regard to “The Birth of a Nation.” As you will read in the next number of the Crisis, we have fought it at every possible point. In spite of the promise of the Mayor [of Chicago] to cut out the two objectionable scenes in the second part, which show a White girl committing suicide to escape from a Negro pursuer, and a mulatto politician trying to force marriage upon the daughter of his White benefactor, these two scenes still form the motif of the really unimportant incidents, of which I enclose a list. I have seen the thing four times and am positive that nothing more will be done about it. Jane Addams saw it when it was in its worst form in New York. I know of no one else from Chicago who saw it. I enclose Miss Addam’s opinion. When we took the thing before the Police Magistrate he told us that he could do nothing about it unless it [led] to a breach of the peace. Some kind of demonstration began in the Liberty Theatre Wednesday night but the colored people took absolutely no part in it, and the only man arrested was a White man. This, of course, is exactly what Littleton, counsel for the producer, Griffith, held in the Magistrates’ Court when we have our hearing and claimed that it might lead to a breach of the peace. Frankly, I do not think you can do one single thing. It has been to me a most liberal education and I purposely am through. The harm it is doing the colored people cannot be estimated. I hear echoes of it wherever I go and have no doubt that this was in the mind of the people who are producing it. Their profits here are something like $14,000 a day and their expenses about $400. I have ceased to worry about it, and if I seem disinterested, kindly remember that we have put six weeks of constant effort of this thing and have gotten nowhere. Sincerely yours, —Mary Childs Nerney, Secretary, NAACP On what grounds does Nerney request censorship? What efforts to get the movie shut down did she describe? The Ku Klux Klan, which had been dormant since the end of Reconstruction in 1877, experienced a resurgence of attention following the popularity of the film. Just months after the film’s release, a second incarnation of the Klan was established at Stone Mountain, Georgia, under the leadership of William Simmons. This new Klan now publicly eschewed violence and received mainstream support. Its embrace of Protestantism, anti-Catholicism, and anti-Semitism, and its appeals for stricter immigration policies, gained the group a level of acceptance by nativists with similar prejudices. The group was not merely a male organization: The ranks of the Klan also included many women, with chapters of its women’s auxiliary in locations across the country. These women’s groups were active in a number of reform-minded activities, such as advocating for prohibition and the distribution of Bibles at public schools. But they also participated in more expressly Klan activities like burning crosses and the public denunciation of Catholics and Jews ( Figure 24.11 ). By 1924, this Second Ku Klux Klan had six million members in the South, West, and, particularly, the Midwest—more Americans than there were in the nation’s labor unions at the time. While the organization publicly abstained from violence, its member continued to employ intimidation, violence, and terrorism against its victims, particularly in the South. The Klan’s newfound popularity proved to be fairly short-lived. Several states effectively combatted the power and influence of the Klan through anti-masking legislation, that is, laws that barred the wearing of masks publicly. As the organization faced a series of public scandals, such as when the Grand Dragon of Indiana was convicted of murdering a White schoolteacher, prominent citizens became less likely to openly express their support for the group without a shield of anonymity. More importantly, influential people and citizen groups explicitly condemned the Klan. Reinhold Niebuhr, a popular Protestant minister and conservative intellectual in Detroit, admonished the group for its ostensibly Protestant zealotry and anti-Catholicism. Jewish organizations, especially the Anti-Defamation League, which had been founded just a couple of years before the reemergence of the Klan, amplified Jewish discontent at being the focus of Klan attention. And the NAACP, which had actively sought to ban the film The Birth of a Nation , worked to lobby congress and educate the public on lynchings. Ultimately, however, it was the Great Depression that put an end to the Klan. As dues-paying members dwindled, the Klan lost its organizational power and sunk into irrelevance until the 1950s. FAITH, FUNDAMENTALISM, AND SCIENCE The sense of degeneration that the Klan and anxiety over mass immigration prompted in the minds of many Americans was in part a response to the process of postwar urbanization. Cities were swiftly becoming centers of opportunity, but the growth of cities, especially the growth of immigrant populations in those cities, sharpened rural discontent over the perception of rapid cultural change. As more of the population flocked to cities for jobs and quality of life, many left behind in rural areas felt that their way of life was being threatened. To rural Americans, the ways of the city seemed sinful and profligate. Urbanites, for their part, viewed rural Americans as hayseeds who were hopelessly behind the times. In this urban/rural conflict, Tennessee lawmakers drew a battle line over the issue of evolution and its contradiction of the accepted, biblical explanation of history. Charles Darwin had first published his theory of natural selection in 1859, and by the 1920s, many standard textbooks contained information about Darwin’s theory of evolution. Fundamentalist Protestants targeted evolution as representative of all that was wrong with urban society. Tennessee’s Butler Act made it illegal “to teach any theory that denies the story of the Divine Creation of man as taught in the Bible, and to teach instead that man has descended from a lower order of animals.” The American Civil Liberties Union (ACLU) hoped to challenge the Butler Act as an infringement of the freedom of speech. As a defendant, the ACLU enlisted teacher and coach John Scopes, who suggested that he may have taught evolution while substituting for an ill biology teacher. Town leaders in Dayton, Tennessee, for their part, sensed an opportunity to promote their town, which had lost more than one-third of its population, and welcomed the ACLU to stage a test case against the Butler Act. The ACLU and the town got their wish as the Scopes Monkey Trial , as the newspapers publicized it, quickly turned into a carnival that captured the attention of the country and epitomized the nation’s urban/rural divide ( Figure 24.12 ). Fundamentalist champion William Jennings Bryan argued the case for the prosecution. Bryan was a three-time presidential candidate and Woodrow Wilson’s Secretary of State until 1915, at which point he began preaching across the country about the spread of secularism and the declining role of religion in education. He was known for offering $100 to anyone who would admit to being descended from an ape. Clarence Darrow, a prominent lawyer and outspoken agnostic, led the defense team. His statement that, “Scopes isn’t on trial, civilization is on trial. No man’s belief will be safe if they win,” struck a chord in society. The outcome of the trial, in which Scopes was found guilty and fined $100, was never really in question, as Scopes himself had confessed to violating the law. Nevertheless, the trial itself proved to be high drama. The drama only escalated when Darrow made the unusual choice of calling Bryan as an expert witness on the Bible. Knowing of Bryan’s convictions of a literal interpretation of the Bible, Darrow peppered him with a series of questions designed to ridicule such a belief. The result was that those who approved of the teaching of evolution saw Bryan as foolish, whereas many rural Americans considered the cross-examination an attack on the Bible and their faith. Defining American H. L. Mencken on the Scopes Trial H. L. Mencken covered the trial for Baltimore’s The Evening Sun. One of most popular writers of social satire of his age, Mencken was very critical of the South, the trial, and especially Bryan. He coined the terms “monkey trial “and “Bible belt.” In the excerpt below, Mencken reflects on the trial’s outcome and its overall importance for the United States. The Scopes trial, from the start, has been carried on in a manner exactly fitted to the anti- evolution law and the simian imbecility under it. There hasn’t been the slightest pretense to decorum. The rustic judge, a candidate for re-election, has postured the yokels like a clown in a ten-cent side show, and almost every word he has uttered has been an undisguised appeal to their prejudices and superstitions. The chief prosecuting attorney, beginning like a competent lawyer and a man of self-respect, ended like a convert at a Billy Sunday revival. It fell to him, finally, to make a clear and astounding statement of theory of justice prevailing under fundamentalism. What he said, in brief, was that a man accused of infidelity had no rights whatever under Tennessee law. . . . Darrow has lost this case. It was lost long before he came to Dayton. But it seems to me that he has nevertheless performed a great public service by fighting it to a finish and in a perfectly serious way. Let no one mistake it for comedy, farcical though it may be in all its details. It serves notice on the country that Neanderthal man is organizing in these forlorn backwaters of the land, led by a fanatic, rid of sense and devoid of conscience. Tennessee, challenging him too timorously and too late, now sees its courts converted into camp meetings and its Bill of Rights made a mock of by its sworn officers of the law. There are other States that had better look to their arsenals before the Hun is at their gates. —H. L. Mencken, The Evening Sun , July 18, 1925 How does Mencken characterize Judge Raulston? About what threat is Mencken warning America? Indicative of the revival of Protestant fundamentalism and the rejection of evolution among rural and White Americans was the rise of Billy Sunday. As a young man, Sunday had gained fame as a baseball player with exceptional skill and speed. Later, he found even more celebrity as the nation’s most revered evangelist, drawing huge crowds at camp meetings around the country. He was one of the most influential evangelists of the time and had access to some of the wealthiest and most powerful families in the country ( Figure 24.13 ). Sunday rallied many Americans around “old-time” fundamentalist religion and garnered support for prohibition. Recognizing Sunday’s popular appeal, Bryan attempted to bring him to Dayton for the Scopes trial, although Sunday politely refused. Even more spectacular than the rise of Billy Sunday was the popularity of Aimee Semple McPherson, a Canadian Pentecostal preacher whose Foursquare Church in Los Angeles catered to the large community of midwestern transplants and newcomers to California ( Figure 24.13 ). Although her message promoted the fundamental truths of the Bible, her style was anything but old fashioned. Dressed in tight-fitting clothes and wearing makeup, she held radio-broadcast services in large venues that resembled concert halls and staged spectacular faith-healing performances. Blending Hollywood style and modern technology with a message of fundamentalist Christianity, McPherson exemplified the contradictions of the decade well before public revelations about her scandalous love affair cost her much of her status and following. 24.3 A New Generation Learning Objectives By the end of this section, you will be able to: Explain the factors that shaped the new morality and the changing role of women in the United States during the 1920s Describe the “new Negro” and the influence of the Harlem Renaissance Analyze the effects of prohibition on American society and culture Describe the character and main authors of the Lost Generation The 1920s was a time of dramatic change in the United States. Many young people, especially those living in big cities, embraced a new morality that was much more permissive than that of previous generations. They listened to jazz music, especially in the nightclubs of Harlem. Although prohibition outlawed alcohol, criminal bootlegging and importing businesses thrived. The decade was not a pleasure cruise for everyone, however; in the wake of the Great War, many were left awaiting the promise of a new generation. A NEW MORALITY Many Americans were disillusioned in the post-World War I era, and their reactions took many forms. Rebellious American youth, in particular, adjusted to the changes by embracing a new morality that was far more permissive than the social mores of their parents. Many young women of the era shed their mother’s morality and adopted the dress and mannerisms of a flapper , the Jazz Age female stereotype, seeking the endless party. Flappers wore shorter skirts, shorter hair, and more makeup, and they drank and smoked with the boys ( Figure 24.14 ). Flappers’ dresses emphasized straight lines from the shoulders to the knees, minimizing breasts and curves while highlighting legs and ankles. The male equivalent of a flapper was a “ sheik ,” although that term has not remained as strong in the American vernacular. At the time, however, many of these fads became a type of conformity, especially among college-aged youths, with the signature bob haircut of the flapper becoming almost universal—in both the United States and overseas. As men and women pushed social and cultural boundaries in the Jazz Age, sexual mores changed and social customs grew more permissive. “Petting parties” or “necking parties” became the rage on college campuses. Psychologist Sigmund Freud and British “sexologist” Havelock Ellis emphasized that sex was a natural and pleasurable part of the human experience. Margaret Sanger, the founder of Planned Parenthood, launched an information campaign on birth control to give women a choice in the realm in which suffrage had changed little—the family. The popularization of contraception and the private space that the automobile offered to teenagers and unwed couples also contributed to changes in sexual behavior. Flappers and sheiks also took their cues from the high-flying romances they saw on movie screens and confessions in movie magazines of immorality on movie sets. Movie posters promised: “Brilliant men, beautiful jazz babies, champagne baths, midnight revels, petting parties in the purple dawn, all ending in one terrific smashing climax that makes you gasp.” And “neckers, petters, white kisses, red kisses, pleasure-mad daughters, sensation-craving mothers . . . the truth: bold, naked, sensational.” New dances and new music—especially jazz—also characterized the Jazz Age. Born out of the African American community, jazz was a uniquely American music. The innovative sound emerged from a number of different communities and from a number of different musical traditions such as blues and ragtime. By the 1920s, jazz had spread from African American clubs in New Orleans and Chicago to reach greater popularity in New York and abroad. One New York jazz establishment, the Cotton Club, became particularly famous and attracted large audiences of hip, young, and White flappers and sheiks to see Black entertainers play jazz ( Figure 24.15 ). THE “NEW WOMAN” The Jazz Age and the proliferation of the flapper lifestyle of the 1920s should not be seen merely as the product of postwar disillusionment and newfound prosperity. Rather, the search for new styles of dress and new forms of entertainment like jazz was part of a larger women’s rights movement. The early 1920s, especially with the ratification of the Nineteenth Amendment guaranteeing full voting rights to women, was a period that witnessed the expansion of women’s political power. The public flaunting of social and sexual norms by flappers represented an attempt to match gains in political equality with gains in the social sphere. Women were increasingly leaving the Victorian era norms of the previous generation behind, as they broadened the concept of women’s liberation to include new forms of social expression such as dance, fashion, women’s clubs, and forays into college and the professions. Nor did the struggle for women’s rights through the promotion and passage of legislation cease in the 1920s. In 1921, Congress passed the Promotion of the Welfare and Hygiene of Maternity and Infancy Act, also known as the Sheppard-Towner Act, which earmarked $1.25 million for well-baby clinics and educational programs, as well as nursing. This funding dramatically reduced the rate of infant mortality. Two years later, in 1923, Alice Paul drafted and promoted an Equal Rights Amendment (ERA) that promised to end all sex discrimination by guaranteeing that “Men and women shall have equal rights throughout the United States and every place subject to its jurisdiction.” Yet, ironically, at precisely the time when the Progressive movement was achieving its long-sought-after goals, the movement itself was losing steam and the Progressive Era was coming to a close. As the heat of Progressive politics grew less intense, voter participation from both sexes declined over the course of the 1920s. After the passage of the Nineteenth Amendment, many women believed that they had accomplished their goals and dropped out of the movement. As a result, the proposed ERA stalled (the ERA eventually passed Congress almost fifty years later in 1972, but then failed to win ratification by a sufficient number of states), and, by the end of the 1920s, Congress even allowed funding for the Sheppard-Towner Act to lapse. The growing lethargy toward women’s rights was happening at a time when an increasing number of women were working for wages in the U.S. economy—not only in domestic service, but in retail, healthcare and education, offices, and manufacturing. Beginning in the 1920s, women’s participation in the labor force increased steadily. However, most were paid less than men for the same type of work based on the rationale that they did not have to support a family. While the employment of single and unmarried women had largely won social acceptance, married women often suffered the stigma that they were working for pin money—frivolous additional discretionary income. THE HARLEM RENAISSANCE AND THE NEW NEGRO It wasn’t only women who found new forms of expression in the 1920s. African Americans were also expanding their horizons and embracing the concept of the “new Negro.” The decade witnessed the continued Great Migration of African Americans to the North, with over half a million fleeing the strict Jim Crow laws of the South. Life in the northern states, as many African Americans discovered, was hardly free of discrimination and segregation. Even without Jim Crow, businesses, property owners, employers, and private citizens typically practiced de facto segregation, which could be quite stifling and oppressive. Nonetheless, many southern Blacks continued to move north into segregated neighborhoods that were already bursting at the seams, because the North, at the very least, offered two tickets toward Black progress: schools and the vote. The Black population of New York City doubled during the decade. As a result, Harlem, a neighborhood at the northern end of Manhattan, became a center for Afro-centric art, music, poetry, and politics. Political expression in the Harlem of the 1920s ran the gamut, as some leaders advocated a return to Africa, while others fought for inclusion and integration. Revived by the wartime migration and fired up by the violence of the postwar riots, urban Blacks developed a strong cultural expression in the 1920s that came to be known as the Harlem Renaissance. In this rediscovery of Black culture, African American artists and writers formulated an independent Black culture and encouraged racial pride, rejecting any emulation of American culture. Claude McKay’s poem “If We Must Die” called on African Americans to start fighting back in the wake of the Red Summer riots of 1919 (discussed in a previous chapter, Figure 24.16 ). Langston Hughes, often nicknamed the “poet laureate” of the movement, invoked sacrifice and the just cause of civil rights in “The Colored Soldier,” while another author of the movement, Zora Neale Hurston, celebrated the life and dialect of rural Blacks in a fictional, all-Black town in Florida. Hurston’s Their Eyes Were Watching God was published in 1937. The new Negro found political expression in a political ideology that celebrated African Americans distinct national identity. This Negro nationalism , as some referred to it, proposed that African Americans had a distinct and separate national heritage that should inspire pride and a sense of community. An early proponent of such nationalism was W. E. B. Du Bois. One of the founders of the NAACP, a brilliant writer and scholar, and the first African American to earn a Ph.D. from Harvard, Du Bois openly rejected assumptions of White supremacy. His conception of Negro nationalism encouraged Africans to work together in support of their own interests, promoted the elevation of Black literature and cultural expression, and, most famously, embraced the African continent as the true homeland of all ethnic Africans—a concept known as Pan-Africanism. Taking Negro nationalism to a new level was Marcus Garvey. Like many Black Americans, the Jamaican immigrant had become utterly disillusioned with the prospect of overcoming racism in the United States in the wake of the postwar riots and promoted a “Back to Africa” movement. To return African Americans to a presumably more welcoming home in Africa, Garvey founded the Black Star Steamship Line . He also started the United Negro Improvement Association (UNIA), which attracted thousands of primarily lower-income working people. UNIA members wore colorful uniforms and promoted the doctrine of a “negritude” that reversed the color hierarchy of White supremacy, prizing Blackness and identifying light skin as a mark of inferiority. Intellectual leaders like Du Bois, whose lighter skin put him low on Garvey’s social order, considered the UNIA leader a charlatan. Garvey was eventually imprisoned for mail fraud and then deported, but his legacy set the stage for Malcolm X and the Black Power movement of the 1960s. PROHIBITION At precisely the same time that African Americans and women were experimenting with new forms of social expression, the country as a whole was undergoing a process of austere and dramatic social reform in the form of alcohol prohibition. After decades of organizing to reduce or end the consumption of alcohol in the United States, temperance groups and the Anti-Saloon League finally succeeded in pushing through the Eighteenth Amendment in 1919, which banned the manufacture, sale, and transportation of intoxicating liquors ( Figure 24.17 ). The law proved difficult to enforce, as illegal alcohol soon poured in from Canada and the Caribbean, and rural Americans resorted to home-brewed “moonshine.” The result was an eroding of respect for law and order, as many people continued to drink illegal liquor. Rather than bringing about an age of sobriety, as Progressive reformers had hoped, it gave rise to a new subculture that included illegal importers, interstate smuggling (or bootlegging ), clandestine saloons referred to as “speakeasies,” hipflasks, cocktail parties, and the organized crime of trafficking liquor. Prohibition also revealed deep political divisions in the nation. The Democratic Party found itself deeply divided between urban, northern “wets” who hated the idea of abstinence, and rural, southern “dries” who favored the amendment. This divided the party and opened the door for the Republican Party to gain ascendancy in the 1920s. All politicians, including Woodrow Wilson, Herbert Hoover, Robert La Follette, and Franklin D. Roosevelt, equivocated in their support for the law. Publicly, they catered to the Anti-Saloon League; however, they failed to provide funding for enforcement. Prohibition sparked a rise in organized crime. “Scarface” Al Capone ( Figure 24.18 ) ran an extensive bootlegging and criminal operation known as the Chicago Outfit or Chicago mafia. By 1927, Capone’s organization included a number of illegal activities including bootlegging, prostitution, gambling, loan sharking, and even murder. His operation was earning him more than $100 million annually, and many local police were on his payroll. Although he did not have a monopoly on crime, his organizational structure was better than many other criminals of his era. His liquor trafficking business and his Chicago soup kitchens during the Great Depression led some Americans to liken Capone to a modern-day Robin Hood. Still, Capone was eventually imprisoned for eleven years for tax evasion, including a stint in California’s notorious Alcatraz prison. THE LOST GENERATION As the country struggled with the effects and side-effects of prohibition, many young intellectuals endeavored to come to grips with a lingering sense of disillusionment. World War I, fundamentalism, and the Red Scare—a pervasive American fear of Communist infiltrators prompted by the success of the Bolshevik Revolution—all left their mark on these intellectuals. Known as the Lost Generation , writers like F. Scott Fitzgerald, Ernest Hemingway, Sinclair Lewis, Edith Wharton, and John Dos Passos expressed their hopelessness and despair by skewering the middle class in their work. They felt alienated from society, so they tried to escape (some literally) to criticize it. Many lived an expatriate life in Paris for the decade, although others went to Rome or Berlin. The Lost Generation writer that best exemplifies the mood of the 1920s was F. Scott Fitzgerald, now considered one of the most influential writers of the twentieth century. His debut novel, This Side of Paradise , describes a generation of youth “grown up to find all gods dead, all wars fought, all faith in man shaken.” The Great Gatsby , published in 1925, exposed the doom that always follows the fun, fast-lived life. Fitzgerald depicted the modern millionaire Jay Gatsby living a profligate life: unscrupulous, coarse, and in love with another man’s wife. Both Fitzgerald and his wife Zelda lived this life as well, squandering the money he made from his writing. My Story F. Scott Fitzgerald on the 1920s In the 1920s, Fitzgerald was one of the most celebrated authors of his day, publishing This Side of Paradise , The Beautiful and Damned , and The Great Gatsby in quick succession. However, his profligate lifestyle with his wife Zelda sapped their funds, and Fitzgerald had to struggle to maintain their lavish lifestyle. Below is an excerpt from “The Crack-Up,” a personal essay by Fitzgerald originally published in Esquire in which he describes his “good life” during the 1920s. It seemed a romantic business to be a successful literary man—you were not ever going to be as famous as a movie star but what note you had was probably longer-lived; you were never going to have the power of a man of strong political or religious convictions but you were certainly more independent. Of course within the practice of your trade you were forever unsatisfied—but I, for one, would not have chosen any other. As the Twenties passed, with my own twenties marching a little ahead of them, my two juvenile regrets—at not being big enough (or good enough) to play football in college, and at not getting overseas during the war—resolved themselves into childish waking dreams of imaginary heroism that were good enough to go to sleep on in restless nights. The big problems of life seemed to solve themselves, and if the business of fixing them was difficult, it made one too tired to think of more general problems. —F. Scott Fitzgerald, “The Crack-Up,” 1936 How does Fitzgerald describe his life in the 1920s? How did his interpretation reflect the reality of the decade? Equally idiosyncratic and disillusioned was writer Ernest Hemingway ( Figure 24.19 ). He lived a peripatetic and adventurous lifestyle in Europe, Cuba, and Africa, working as an ambulance driver in Italy during World War I and traveling to Spain in the 1930s to cover the civil war there. His experiences of war and tragedy stuck with him, emerging in colorful scenes in his novels The Sun Also Rises (1926), A Farewell to Arms (1929), and For Whom the Bell Tolls (1940). In 1952, his novella, The Old Man and the Sea , won the Pulitzer Prize. Two years later, he won the Nobel Prize in Literature for this book and his overall influence on contemporary style. Not all Lost Generation writers were like Fitzgerald or Hemingway. The writing of Sinclair Lewis, rather than expressing a defined disillusionment, was more influenced by the Progressivism of the previous generation. In Babbitt (1922), he examined the “sheep following the herd” mentality that conformity promoted. He satirized American middle-class life as pleasure seeking and mindless. Similarly, writer Edith Wharton celebrated life in old New York, a vanished society, in The Age of Innocence , in 1920. Wharton came from a very wealthy, socialite family in New York, where she was educated by tutors and never attended college. She lived for many years in Europe; during the Great War, she worked in Paris helping women establish businesses. 24.4 Republican Ascendancy: Politics in the 1920s Learning Objectives By the end of this section, you will be able to: Discuss Warren G. Harding’s strengths and weaknesses as president Explain how Calvin Coolidge was able to defeat the Democratic Party Explain what Calvin Coolidge meant by “the business of America is business” The election of 1920 saw the weakening of the Democratic Party. The death of Theodore Roosevelt and Woodrow Wilson’s ill health meant the passing of a generation of Progressive leaders. The waning of the Red Scare took with it the last vestiges of Progressive zeal, and Wilson’s support of the League of Nations turned Irish and German immigrants against the Democrats. Americans were tired of reform, tired of witch hunts, and were more than ready for a return to “normalcy.” Above all, the 1920s signaled a return to a pro-business government—almost a return to the laissez-faire politics of the Gilded Age of the late nineteenth century. Calvin Coolidge’s statement that “the chief business of the American people is business,” often rendered as “the business of America is business” became the dominant attitude. WARREN HARDING AND THE RETURN TO NORMALCY In the election of 1920, professional Republicans were eager to nominate a man whom they could manage and control. Warren G. Harding, a senator from Ohio, represented just such a man ( Figure 24.20 ). Before his nomination, Harding stated, “America’s present need is not heroics but healing; not nostrums but normalcy; not revolution but restoration.” Harding was genial and affable, but not everyone appreciated his speeches; Democratic presidential-hopeful William Gibbs McAdoo described Harding’s speeches as “an army of pompous phrases moving across the landscape in search of an idea.” H. L. Mencken, the great social critic of the 1920s, wrote of Harding’s speaking, “It drags itself out of the dark abysm of pish, and crawls insanely up to the top-most pinnacle of posh. It is rumble and bumble. It is flap and doodle. It is balder and dash.” Harding was known for enjoying golf, alcohol, and poker (not necessarily in that order). Although his critics depicted him as weak, lazy, or incompetent, he was actually quite shrewd and politically astute. Together with his running mate, Calvin Coolidge, the governor of Massachusetts, they attracted the votes of many Americans who sought Harding’s promised return to normalcy . In the election, Harding defeated Governor James Cox of Ohio by the greatest majority in the history of two-party politics: 61 percent of the popular vote. Harding’s cabinet reflected his pro-business agenda. Herbert Hoover, a millionaire mechanical engineer and miner, became his Secretary of Commerce. Hoover had served as head of the relief effort for Belgium during World War I and helped to feed those in Russia and Germany after the war ended. He was a very effective administrator, seeking to limit inefficiency in the government and promoting partnerships between government and businesses. Harding’s Secretary of the Treasury, Andrew Mellon, was also a pro-business multimillionaire with a fortune built in banking and aluminum. Even more so than Hoover, Mellon entered public service with a strong sense that government should run as efficiently as any business, famously writing that “the Government is just a business, and can and should be run on business principles.” Consistent with his principles of running government with business-like efficiency, Harding proposed and signed into law tax rate cuts as well as the country’s first formal budgeting process, which created a presidential budget director and required that the president submit an annual budget to Congress. These policies helped to reduce the debt that the United States had incurred during World War I. However, as Europe began to recover, U.S. exports to the continent dwindled. In an effort to protect U.S. agriculture and other businesses threatened by lower-priced imports, Harding pushed through the Emergency Tariff of 1921. This defensive tariff had the effect of increasing American purchasing power, although it also inflated the prices of many goods. In the area of foreign policy, Harding worked to preserve the peace through international cooperation and the reduction of armaments around the world. Despite the refusal of the U.S. Senate to ratify the Treaty of Versailles, Harding was able to work with Germany and Austria to secure a formal peace. He convened a conference in Washington that brought world leaders together to agree on reducing the threat of future wars by reducing armaments. Out of these negotiations came a number of treaties designed to foster cooperation in the Far East, reduce the size of navies around the world, and establish guidelines for submarine usage. These agreements ultimately fell apart in the 1930s, as the world descended into war again. But, at the time, they were seen as a promising path to maintaining the peace. Despite these developments, the Harding administration has gone down in history as one that was especially ridden with scandal. While Harding was personally honest, he surrounded himself with politicians who weren’t. Harding made the mistake of often turning to unscrupulous advisors or even his “Ohio Gang” of drinking and poker buddies for advice and guidance. And, as he himself recognized, this group tended to cause him grief. “I have no trouble with my enemies,” he once commented. “I can take care of my enemies in a fight. But my friends, my goddamned friends, they’re the ones who keep me walking the floor at nights!” The scandals mounted quickly. From 1920 to 1923, Secretary of the Interior Albert B. Fall was involved in a scam that became known as the Teapot Dome scandal . Fall had leased navy reserves in Teapot Dome, Wyoming, and two other sites in California to private oil companies without opening the bidding to other companies. In exchange, the companies gave him $300,000 in cash and bonds, as well as a herd of cattle for his ranch. Fall was convicted of accepting bribes from the oil companies; he was fined $100,000 and sentenced to a year in prison. It was the first time that a cabinet official had received such a sentence. In 1923, Harding also learned that the head of the Veterans’ Bureau, Colonel Charles Forbes, had absconded with most of the $250 million set aside for extravagant bureau functions. Harding allowed Forbes to resign and leave the country; however, after the president died, Forbes returned and was tried, convicted, and sentenced to two years in Leavenworth prison. Although the Harding presidency had a number of large successes and variety of dark scandals, it ended before the first term was up. In July 1923, while traveling in Seattle, the president suffered a heart attack. On August 2, in his weakened condition, he suffered a stroke and died in San Francisco, leaving the presidency to his vice president, Calvin Coolidge. As for Harding, few presidents were so deeply mourned by the populace. His kindly nature and ability to poke fun at himself endeared him to the public. A MAN OF FEW WORDS Coolidge ended the scandals, but did little beyond that. Walter Lippman wrote in 1926 that “Mr. Coolidge’s genius for inactivity is developed to a very high point. It is a grim, determined, alert inactivity, which keeps Mr. Coolidge occupied constantly.” Coolidge had a strong belief in the Puritan work ethic: Work hard, save your money, keep your mouth shut and listen, and good things will happen to you. Known as “Silent Cal,” his clean image seemed capable of cleaning up scandals left by Harding. Republicans—and the nation—now had a president who combined a preference for normalcy with the respectability and honesty that was absent from the Harding administration. Coolidge’s first term was devoted to eliminating the taint of scandal that Harding had brought to the White House. Domestically, Coolidge adhered to the creed: “The business of America is business.” He stood in awe of Andrew Mellon and followed his fiscal policies, which made him the only president to turn a legitimate profit in the White House. Coolidge believed the rich were worthy of their property and that poverty was the wage of sin. Most importantly, Coolidge believed that since only the rich best understood their own interests, the government should let businessmen handle their own affairs with as little federal intervention as possible. Coolidge was quoted as saying, “The man who builds a factory builds a temple. The man who works there worships there.” Thus, silence and inactivity became the dominant characteristics of the Coolidge presidency. Coolidge’s legendary reserve was famous in Washington society. Contemporaries told a possibly apocryphal story of how, at a dinner party at the White House, a woman bet her friends that she could get Coolidge to say more than three words. He looked at her and said, “you lose.” The 1924 election saw Coolidge win easily over the divided Democrats, who fought over their nomination. Southerners wanted to nominate pro-prohibition, pro-Klan, anti-immigrant candidate William G. McAdoo. The eastern establishment wanted Alfred E. Smith, a Catholic, urban, and anti-prohibition candidate. After many battles, they compromised on corporation lawyer John W. Davis. Midwesterner Robert M. La Follette, promoted by farmers, socialists, and labor unions, attempted to resurrect the Progressive Party. Coolidge easily beat both candidates. THE ELECTION OF 1928 This cultural battle between the forces of reaction and rebellion appeared to culminate with the election of 1928, the height of Republican ascendancy. On August 2, 1927, Coolidge announced that he would not be participating in the 1928 election; “I choose not to run,” was his comment ( Figure 24.21 ). Republicans promoted the heir apparent, Secretary of Commerce Herbert Hoover. The Democrats nominated Governor Alfred E. Smith of New York. Smith represented everything that small-town, rural America hated: He was Irish, Catholic, anti-prohibition, and a big-city politician. He was very flamboyant and outspoken, which also did not go over well with many Americans. Republican prosperity carried the day once again, and Hoover won easily with twenty-one million votes over Al Smith’s fifteen million. The stock market continued to rise, and prosperity was the watchword of the day. Many Americans who had not done so before invested in the market, believing that the prosperous times would continue. As Hoover came into office, Americans had every reason to believe that prosperity would continue forever. In less than a year, however, the bubble would burst, and a harsh reality would take its place.
psychology
Summary 15.1 What Are Psychological Disorders? Psychological disorders are conditions characterized by abnormal thoughts, feelings, and behaviors. Although challenging, it is essential for psychologists and mental health professionals to agree on what kinds of inner experiences and behaviors constitute the presence of a psychological disorder. Inner experiences and behaviors that are atypical or violate social norms could signify the presence of a disorder; however, each of these criteria alone is inadequate. Harmful dysfunction describes the view that psychological disorders result from the inability of an internal mechanism to perform its natural function. Many of the features of harmful dysfunction conceptualization have been incorporated in the APA’s formal definition of psychological disorders. According to this definition, the presence of a psychological disorder is signaled by significant disturbances in thoughts, feelings, and behaviors; these disturbances must reflect some kind of dysfunction (biological, psychological, or developmental), must cause significant impairment in one’s life, and must not reflect culturally expected reactions to certain life events. 15.2 Diagnosing and Classifying Psychological Disorders The diagnosis and classification of psychological disorders is essential in studying and treating psychopathology. The classification system used by most U.S. professionals is the DSM-5. The first edition of the DSM was published in 1952, and has undergone numerous revisions. The 5th and most recent edition, the DSM-5, was published in 2013. The diagnostic manual includes a total of 237 specific diagnosable disorders, each described in detail, including its symptoms, prevalence, risk factors, and comorbidity. Over time, the number of diagnosable conditions listed in the DSM has grown steadily, prompting criticism from some. Nevertheless, the diagnostic criteria in the DSM are more explicit than that of any other system, which makes the DSM system highly desirable for both clinical diagnosis and research. 15.3 Perspectives on Psychological Disorders Psychopathology is very complex, involving a plethora of etiological theories and perspectives. For centuries, psychological disorders were viewed primarily from a supernatural perspective and thought to arise from divine forces or possession from spirits. Some cultures continue to hold this supernatural belief. Today, many who study psychopathology view mental illness from a biological perspective, whereby psychological disorders are thought to result largely from faulty biological processes. Indeed, scientific advances over the last several decades have provided a better understanding of the genetic, neurological, hormonal, and biochemical bases of psychopathology. The psychological perspective, in contrast, emphasizes the importance of psychological factors (e.g., stress and thoughts) and environmental factors in the development of psychological disorders. A contemporary, promising approach is to view disorders as originating from an integration of biological and psychosocial factors. The diathesis-stress model suggests that people with an underlying diathesis, or vulnerability, for a psychological disorder are more likely than those without the diathesis to develop the disorder when faced with stressful events. 15.4 Anxiety Disorders Anxiety disorders are a group of disorders in which a person experiences excessive, persistent, and distressing fear and anxiety that interferes with normal functioning. Anxiety disorders include specific phobia: a specific unrealistic fear; social anxiety disorder: extreme fear and avoidance of social situations; panic disorder: suddenly overwhelmed by panic even though there is no apparent reason to be frightened; agoraphobia: an intense fear and avoidance of situations in which it might be difficult to escape; and generalized anxiety disorder: a relatively continuous state of tension, apprehension, and dread. 15.5 Obsessive-Compulsive and Related Disorders Obsessive-compulsive and related disorders are a group of DSM-5 disorders that overlap somewhat in that they each involve intrusive thoughts and/or repetitive behaviors. Perhaps the most recognized of these disorders is obsessive-compulsive disorder, in which a person is obsessed with unwanted, unpleasant thoughts and/or compulsively engages in repetitive behaviors or mental acts, perhaps as a way of coping with the obsessions. Body dysmorphic disorder is characterized by the individual becoming excessively preoccupied with one or more perceived flaws in his physical appearance that are either nonexistent or unnoticeable to others. Preoccupation with the perceived physical defects causes the person to experience significant anxiety regarding how he appears to others. Hoarding disorder is characterized by persistent difficulty in discarding or parting with objects, regardless of their actual value, often resulting in the accumulation of items that clutter and congest her living area. 15.6 Posttraumatic Stress Disorder Posttraumatic stress disorder (PTSD) was described through much of the 20th century and was referred to as shell shock and combat neurosis in the belief that its symptoms were thought to emerge from the stress of active combat. Today, PTSD is defined as a disorder in which the experience of a traumatic or profoundly stressful event, such as combat, sexual assault, or natural disaster, produces a constellation of symptoms that must last for one month or more. These symptoms include intrusive and distressing memories of the event, flashbacks, avoidance of stimuli or situations that are connected to the event, persistently negative emotional states, feeling detached from others, irritability, proneness toward outbursts, and a tendency to be easily startled. Not everyone who experiences a traumatic event will develop PTSD; a variety of risk factors associated with its development have been identified. 15.7 Mood Disorders Mood disorders are those in which the person experiences severe disturbances in mood and emotion. They include depressive disorders and bipolar and related disorders. Depressive disorders include major depressive disorder, which is characterized by episodes of profound sadness and loss of interest or pleasure in usual activities and other associated features, and persistent depressive disorder, which marked by a chronic state of sadness. Bipolar disorder is characterized by mood states that vacillate between sadness and euphoria; a diagnosis of bipolar disorder requires experiencing at least one manic episode, which is defined as a period of extreme euphoria, irritability, and increased activity. Mood disorders appear to have a genetic component, with genetic factors playing a more prominent role in bipolar disorder than in depression. Both biological and psychological factors are important in the development of depression. People who suffer from mental health problems, especially mood disorders, are at heightened risk for suicide. 15.8 Schizophrenia Schizophrenia is a severe disorder characterized by a complete breakdown in one’s ability to function in life; it often requires hospitalization. People with schizophrenia experience hallucinations and delusions, and they have extreme difficulty regulating their emotions and behavior. Thinking is incoherent and disorganized, behavior is extremely bizarre, emotions are flat, and motivation to engage in most basic life activities is lacking. Considerable evidence shows that genetic factors play a central role in schizophrenia; however, adoption studies have highlighted the additional importance of environmental factors. Neurotransmitter and brain abnormalities, which may be linked to environmental factors such as obstetric complications or exposure to influenza during the gestational period, have also been implicated. A promising new area of schizophrenia research involves identifying individuals who show prodromal symptoms and following them over time to determine which factors best predict the development of schizophrenia. Future research may enable us to pinpoint those especially at risk for developing schizophrenia and who may benefit from early intervention. 15.9 Dissociative Disorders The main characteristic of dissociative disorders is that people become dissociated from their sense of self, resulting in memory and identity disturbances. Dissociative disorders listed in the DSM-5 include dissociative amnesia, depersonalization/derealization disorder, and dissociative identity disorder. A person with dissociative amnesia is unable to recall important personal information, often after a stressful or traumatic experience. Depersonalization/derealization disorder is characterized by recurring episodes of depersonalization (i.e., detachment from or unfamiliarity with the self) and/or derealization (i.e., detachment from or unfamiliarity with the world). A person with dissociative identity disorder exhibits two or more well-defined and distinct personalities or identities, as well as memory gaps for the time during which another identity was present. Dissociative identity disorder has generated controversy, mainly because some believe its symptoms can be faked by patients if presenting its symptoms somehow benefits the patient in avoiding negative consequences or taking responsibility for one’s actions. The diagnostic rates of this disorder have increased dramatically following its portrayal in popular culture. However, many people legitimately suffer over the course of a lifetime with this disorder. 15.10 Personality Disorders Individuals with personality disorders exhibit a personality style that is inflexible, causes distress and impairment, and creates problems for themselves and others. The DSM-5 recognizes 10 personality disorders, organized into three clusters. The disorders in Cluster A include those characterized by a personality style that is odd and eccentric. Cluster B includes personality disorders characterized chiefly by a personality style that is impulsive, dramatic, highly emotional, and erratic, and those in Cluster C are characterized by a nervous and fearful personality style. Two Cluster B personality disorders, borderline personality disorder and antisocial personality disorder, are especially problematic. People with borderline personality disorder show marked instability in mood, behavior, and self-image, as well as impulsivity. They cannot stand to be alone, are unpredictable, have a history of stormy relationships, and frequently display intense and inappropriate anger. Genetic factors and adverse childhood experiences (e.g., sexual abuse) appear to be important in its development. People with antisocial personality display a lack of regard for the rights of others; they are impulsive, deceitful, irresponsible, and unburdened by any sense of guilt. Genetic factors and socialization both appear to be important in the origin of antisocial personality disorder. Research has also shown that those with this disorder do not experience emotions the way most other people do. 15.11 Disorders in Childhood Neurodevelopmental disorders are a group of disorders that are typically diagnosed during childhood and are characterized by developmental deficits in personal, social, academic, and intellectual realms; these disorders include attention deficit/hyperactivity disorder (ADHD) and autism spectrum disorder. ADHD is characterized by a pervasive pattern of inattention and/or hyperactive and impulsive behavior that interferes with normal functioning. Genetic and neurobiological factors contribute to the development of ADHD, which can persist well into adulthood and is often associated with poor long-term outcomes. The major features of autism spectrum disorder include deficits in social interaction and communication and repetitive movements or interests. As with ADHD, genetic factors appear to play a prominent role in the development of autism spectrum disorder; exposure to environmental pollutants such as mercury have also been linked to the development of this disorder. Although it is believed by some that autism is triggered by the MMR vaccination, evidence does not support this claim.
Chapter Outline 15.1 What Are Psychological Disorders? 15.2 Diagnosing and Classifying Psychological Disorders 15.3 Perspectives on Psychological Disorders 15.4 Anxiety Disorders 15.5 Obsessive-Compulsive and Related Disorders 15.6 Posttraumatic Stress Disorder 15.7 Mood Disorders 15.8 Schizophrenia 15.9 Dissociative Disorders 15.10 Personality Disorders 15.11 Disorders in Childhood Introduction On Monday, September 16, 2013, a gunman killed 12 people as the workday began at the Washington Navy Yard in Washington, DC. Aaron Alexis, 34, had a troubled history: he thought that he was being controlled by radio waves. He called the police to complain about voices in his head and being under surveillance by “shadowy forces” (Thomas, Levine, Date, & Cloherty, 2013). While Alexis’s actions cannot be excused, it is clear that he had some form of mental illness. Mental illness is not necessarily a cause of violence; it is far more likely that the mentally ill will be victims rather than perpetrators of violence (Stuart, 2003). If, however, Alexis had received the help he needed, this tragedy might have been averted.
[ { "answer": { "ans_choice": 0, "ans_text": "the inability of an psychological mechanism to perform its function" }, "bloom": null, "hl_context": "If none of the criteria discussed so far is adequate by itself to define the presence of a psychological disorder , how can a disorder be conceptualized ? Many efforts have been made to identify the specific dimensions of psychological disorders , yet none is entirely satisfactory . No universal definition of psychological disorder exists that can apply to all situations in which a disorder is thought to be present ( Zachar & Kendler , 2007 ) . <hl> However , one of the more influential conceptualizations was proposed by Wakefield ( 1992 ) , who defined psychological disorder as a harmful dysfunction . <hl> Wakefield argued that natural internal mechanisms — that is , psychological processes honed by evolution , such as cognition , perception , and learning — have important functions , such as enabling us to experience the world the way others do and to engage in rational thought , problem solving , and communication . For example , learning allows us to associate a fear with a potential danger in such a way that the intensity of fear is roughly equal to the degree of actual danger . <hl> Dysfunction occurs when an internal mechanism breaks down and can no longer perform its normal function . <hl> But , the presence of a dysfunction by itself does not determine a disorder . The dysfunction must be harmful in that it leads to negative consequences for the individual or for others , as judged by the standards of the individual ’ s culture . The harm may include significant internal anguish ( e . g . , high levels of anxiety or depression ) or problems in day-to-day living ( e . g . , in one ’ s social or work life ) .", "hl_sentences": "However , one of the more influential conceptualizations was proposed by Wakefield ( 1992 ) , who defined psychological disorder as a harmful dysfunction . Dysfunction occurs when an internal mechanism breaks down and can no longer perform its normal function .", "question": { "cloze_format": "In the harmful dysfunction definition of psychological disorders, dysfunction involves ________.", "normal_format": "In the harmful dysfunction definition of psychological disorders, what does dysfunction involve?", "question_choices": [ "the inability of an psychological mechanism to perform its function", "the breakdown of social order in one’s community ", "communication problems in one’s immediate family", "all the above" ], "question_id": "fs-idm86813760", "question_text": "In the harmful dysfunction definition of psychological disorders, dysfunction involves ________." }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 1, "ans_text": "lead to significant distress and impairment in one’s life" }, "bloom": null, "hl_context": "<hl> The disturbances lead to significant distress or disability in one ’ s life . <hl> <hl> A person ’ s inner experiences and behaviors are considered to reflect a psychological disorder if they cause the person considerable distress , or greatly impair his ability to function as a normal individual ( often referred to as functional impairment , or occupational and social impairment ) . <hl> As an illustration , a person ’ s fear of social situations might be so distressing that it causes the person to avoid all social situations ( e . g . , preventing that person from being able to attend class or apply for a job ) .", "hl_sentences": "The disturbances lead to significant distress or disability in one ’ s life . A person ’ s inner experiences and behaviors are considered to reflect a psychological disorder if they cause the person considerable distress , or greatly impair his ability to function as a normal individual ( often referred to as functional impairment , or occupational and social impairment ) .", "question": { "cloze_format": "Patterns of inner experience and behavior are thought to reflect the presence of a psychological disorder if they ________.", "normal_format": "Patterns of inner experience and behavior are thought to reflect the presence of a psychological disorder if they what?", "question_choices": [ "are highly atypical", "lead to significant distress and impairment in one’s life", "embarrass one’s friends and/or family", "violate the norms of one’s culture" ], "question_id": "fs-idm30650016", "question_text": "Patterns of inner experience and behavior are thought to reflect the presence of a psychological disorder if they ________." }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 3, "ans_text": "Diagnostic and Statistical Manual of Mental Disorders" }, "bloom": null, "hl_context": "<hl> The Diagnostic and Statistical Manual of Mental Disorders ( DSM ) Although a number of classification systems have been developed over time , the one that is used by most mental health professionals in the United States is the Diagnostic and Statistical Manual of Mental Disorders ( DSM - 5 ) , published by the American Psychiatric Association ( 2013 ) . <hl> ( Note that the American Psychiatric Association differs from the American Psychological Association ; both are abbreviated APA . ) The first edition of the DSM , published in 1952 , classified psychological disorders according to a format developed by the U . S . Army during World War II ( Clegg , 2012 ) . In the years since , the DSM has undergone numerous revisions and editions . The most recent edition , published in 2013 , is the DSM - 5 ( APA , 2013 ) . The DSM - 5 includes many categories of disorders ( e . g . , anxiety disorders , depressive disorders , and dissociative disorders ) . Each disorder is described in detail , including an overview of the disorder ( diagnostic features ) , specific symptoms required for diagnosis ( diagnostic criteria ) , prevalence information ( what percent of the population is thought to be afflicted with the disorder ) , and risk factors associated with the disorder . Figure 15.4 shows lifetime prevalence rates — the percentage of people in a population who develop a disorder in their lifetime — of various psychological disorders among U . S . adults . These data were based on a national sample of 9,282 U . S . residents ( National Comorbidity Survey , 2007 ) .", "hl_sentences": "The Diagnostic and Statistical Manual of Mental Disorders ( DSM ) Although a number of classification systems have been developed over time , the one that is used by most mental health professionals in the United States is the Diagnostic and Statistical Manual of Mental Disorders ( DSM - 5 ) , published by the American Psychiatric Association ( 2013 ) .", "question": { "cloze_format": "The letters in the abbreviation DSM-5 stand for ________.", "normal_format": "What do the letters in the abbreviation DSM-5 stand for?", "question_choices": [ "Diseases and Statistics Manual of Medicine", "Diagnosable Standards Manual of Mental Disorders", "Diseases and Symptoms Manual of Mental Disorders", "Diagnostic and Statistical Manual of Mental Disorders" ], "question_id": "fs-idp96795840", "question_text": "The letters in the abbreviation DSM-5 stand for ________." }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 0, "ans_text": "vulnerability and adverse experiences" }, "bloom": null, "hl_context": "<hl> The diathesis-stress model ( Zuckerman , 1999 ) integrates biological and psychosocial factors to predict the likelihood of a disorder . <hl> <hl> This diathesis-stress model suggests that people with an underlying predisposition for a disorder ( i . e . , a diathesis ) are more likely than others to develop a disorder when faced with adverse environmental or psychological events ( i . e . , stress ) , such as childhood maltreatment , negative life events , trauma , and so on . <hl> <hl> A diathesis is not always a biological vulnerability to an illness ; some diatheses may be psychological ( e . g . , a tendency to think about life events in a pessimistic , self-defeating way ) . <hl>", "hl_sentences": "The diathesis-stress model ( Zuckerman , 1999 ) integrates biological and psychosocial factors to predict the likelihood of a disorder . This diathesis-stress model suggests that people with an underlying predisposition for a disorder ( i . e . , a diathesis ) are more likely than others to develop a disorder when faced with adverse environmental or psychological events ( i . e . , stress ) , such as childhood maltreatment , negative life events , trauma , and so on . A diathesis is not always a biological vulnerability to an illness ; some diatheses may be psychological ( e . g . , a tendency to think about life events in a pessimistic , self-defeating way ) .", "question": { "cloze_format": "The diathesis-stress model presumes that psychopathology results from ________.", "normal_format": "The diathesis-stress model presumes that psychopathology results from what?", "question_choices": [ "vulnerability and adverse experiences", "biochemical factors", "chemical imbalances and structural abnormalities in the brain", "adverse childhood experiences" ], "question_id": "fs-idp130712464", "question_text": "The diathesis-stress model presumes that psychopathology results from ________." }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 2, "ans_text": "biological" }, "bloom": null, "hl_context": "Since the 1950s , researchers have noted that depressed individuals have abnormal levels of cortisol , a stress hormone released into the blood by the neuroendocrine system during times of stress ( Mackin & Young , 2004 ) . When cortisol is released , the body initiates a fight-or-flight response in reaction to a threat or danger . <hl> Many people with depression show elevated cortisol levels ( Holsboer & Ising , 2010 ) , especially those reporting a history of early life trauma such as the loss of a parent or abuse during childhood ( Baes , Tofoli , Martins , & Juruena , 2012 ) . <hl> Such findings raise the question of whether high cortisol levels are a cause or a consequence of depression . High levels of cortisol are a risk factor for future depression ( Halligan , Herbert , Goodyer , & Murray , 2007 ) , and cortisol activates activity in the amygdala while deactivating activity in the PFC ( McEwen , 2005 ) — both brain disturbances are connected to depression . Thus , high cortisol levels may have a causal effect on depression , as well as on its brain function abnormalities ( van Praag , 2005 ) . Also , because stress results in increased cortisol release ( Michaud , Matheson , Kelly , Anisman , 2008 ) , it is equally reasonable to assume that stress may precipitate depression .", "hl_sentences": "Many people with depression show elevated cortisol levels ( Holsboer & Ising , 2010 ) , especially those reporting a history of early life trauma such as the loss of a parent or abuse during childhood ( Baes , Tofoli , Martins , & Juruena , 2012 ) .", "question": { "cloze_format": "Dr. Anastasia believes that major depressive disorder is caused by an over-secretion of cortisol. His view on the cause of major depressive disorder reflects a ________ perspective.", "normal_format": "Dr. Anastasia believes that major depressive disorder is caused by an over-secretion of cortisol. His view on the cause of major depressive disorder reflects which perspective?", "question_choices": [ "psychological", "supernatural", "biological", "diathesis-stress" ], "question_id": "fs-idm19981600", "question_text": "Dr. Anastasia believes that major depressive disorder is caused by an over-secretion of cortisol. His view on the cause of major depressive disorder reflects a ________ perspective." }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 1, "ans_text": "generalized anxiety disorder" }, "bloom": null, "hl_context": "<hl> Alex suffers from generalized anxiety disorder : a relatively continuous state of excessive , uncontrollable , and pointless worry and apprehension . <hl> <hl> People with generalized anxiety disorder often worry about routine , everyday things , even though their concerns are unjustified ( Figure 15.10 ) . <hl> For example , an individual may worry about her health and finances , the health of family members , the safety of her children , or minor matters ( e . g . , being late for an appointment ) without having any legitimate reason for doing so ( APA , 2013 ) . A diagnosis of generalized anxiety disorder requires that the diffuse worrying and apprehension characteristic of this disorder — what Sigmund Freud referred to as free-floating anxiety — is not part of another disorder , occurs more days than not for at least six months , and is accompanied by any three of the following symptoms : restlessness , difficulty concentrating , being easily fatigued , muscle tension , irritability , and sleep difficulties .", "hl_sentences": "Alex suffers from generalized anxiety disorder : a relatively continuous state of excessive , uncontrollable , and pointless worry and apprehension . People with generalized anxiety disorder often worry about routine , everyday things , even though their concerns are unjustified ( Figure 15.10 ) .", "question": { "cloze_format": "When a person is in a continuous state of excessive, pointless worry and apprehension, he has ____.", "normal_format": "In which of the following anxiety disorders is the person in a continuous state of excessive, pointless worry and apprehension?", "question_choices": [ "panic disorder", "generalized anxiety disorder", "agoraphobia", "social anxiety disorder" ], "question_id": "fs-idm76487856", "question_text": "In which of the following anxiety disorders is the person in a continuous state of excessive, pointless worry and apprehension?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 2, "ans_text": "avoiding eye contact" }, "bloom": null, "hl_context": "When people with social anxiety disorder are unable to avoid situations that provoke anxiety , they typically perform safety behaviors : mental or behavioral acts that reduce anxiety in social situations by reducing the chance of negative social outcomes . <hl> Safety behaviors include avoiding eye contact , rehearsing sentences before speaking , talking only briefly , and not talking about oneself ( Alden & Bieling , 1998 ) . <hl> Other examples of safety behaviors include the following ( Marker , 2013 ):", "hl_sentences": "Safety behaviors include avoiding eye contact , rehearsing sentences before speaking , talking only briefly , and not talking about oneself ( Alden & Bieling , 1998 ) .", "question": { "cloze_format": "___ would constitute a safety behavior.", "normal_format": "Which of the following would constitute a safety behavior?", "question_choices": [ "encountering a phobic stimulus in the company of other people", "avoiding a field where snakes are likely to be present", "avoiding eye contact", "worrying as a distraction from painful memories" ], "question_id": "fs-idm124218256", "question_text": "Which of the following would constitute a safety behavior?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 0, "ans_text": "mentally counting backward from 1,000" }, "bloom": null, "hl_context": "Compulsions are repetitive and ritualistic acts that are typically carried out primarily as a means to minimize the distress that obsessions trigger or to reduce the likelihood of a feared event ( APA , 2013 ) . <hl> Compulsions often include such behaviors as repeated and extensive hand washing , cleaning , checking ( e . g . , that a door is locked ) , and ordering ( e . g . , lining up all the pencils in a particular way ) , and they also include such mental acts as counting , praying , or reciting something to oneself ( Figure 15.11 ) . <hl> Compulsions characteristic of OCD are not performed out of pleasure , nor are they connected in a realistic way to the source of the distress or feared event . Approximately 2.3 % of the U . S . population will experience OCD in their lifetime ( Ruscio , Stein , Chiu , & Kessler , 2010 ) and , if left untreated , OCD tends to be a chronic condition creating lifelong interpersonal and psychological problems ( Norberg , Calamari , Cohen , & Riemann , 2008 ) .", "hl_sentences": "Compulsions often include such behaviors as repeated and extensive hand washing , cleaning , checking ( e . g . , that a door is locked ) , and ordering ( e . g . , lining up all the pencils in a particular way ) , and they also include such mental acts as counting , praying , or reciting something to oneself ( Figure 15.11 ) .", "question": { "cloze_format": "___ best illustrates a compulsion.", "normal_format": "Which of the following best illustrates a compulsion?", "question_choices": [ "mentally counting backward from 1,000", "persistent fear of germs", "thoughts of harming a neighbor", "falsely believing that a spouse has been cheating" ], "question_id": "fs-idm139657840", "question_text": "Which of the following best illustrates a compulsion?" }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 2, "ans_text": "are related to hyperactivity in the orbitofrontal cortex" }, "bloom": null, "hl_context": "<hl> A brain region that is believed to play a critical role in OCD is the orbitofrontal cortex ( Kopell & Greenberg , 2008 ) , an area of the frontal lobe involved in learning and decision-making ( Rushworth , Noonan , Boorman , Walton , & Behrens , 2011 ) ( Figure 15.13 ) . <hl> <hl> In people with OCD , the orbitofrontal cortex becomes especially hyperactive when they are provoked with tasks in which , for example , they are asked to look at a photo of a toilet or of pictures hanging crookedly on a wall ( Simon , Kaufmann , Müsch , Kischkel , & Kathmann , 2010 ) . <hl> The orbitofrontal cortex is part of a series of brain regions that , collectively , is called the OCD circuit ; this circuit consists of several interconnected regions that influence the perceived emotional value of stimuli and the selection of both behavioral and cognitive responses ( Graybiel & Rauch , 2000 ) . As with the orbitofrontal cortex , other regions of the OCD circuit show heightened activity during symptom provocation ( Rotge et al . , 2008 ) , which suggests that abnormalities in these regions may produce the symptoms of OCD ( Saxena , Bota , & Brody , 2001 ) . Consistent with this explanation , people with OCD show a substantially higher degree of connectivity of the orbitofrontal cortex and other regions of the OCD circuit than do those without OCD ( Beucke et al . , 2013 ) .", "hl_sentences": "A brain region that is believed to play a critical role in OCD is the orbitofrontal cortex ( Kopell & Greenberg , 2008 ) , an area of the frontal lobe involved in learning and decision-making ( Rushworth , Noonan , Boorman , Walton , & Behrens , 2011 ) ( Figure 15.13 ) . In people with OCD , the orbitofrontal cortex becomes especially hyperactive when they are provoked with tasks in which , for example , they are asked to look at a photo of a toilet or of pictures hanging crookedly on a wall ( Simon , Kaufmann , Müsch , Kischkel , & Kathmann , 2010 ) .", "question": { "cloze_format": "Research indicates that the symptoms of OCD ________.", "normal_format": "What does research indicate about the symptoms of OCD?", "question_choices": [ "are similar to the symptoms of panic disorder", "are triggered by low levels of stress hormones", "are related to hyperactivity in the orbitofrontal cortex", "are reduced if people are asked to view photos of stimuli that trigger the symptoms" ], "question_id": "fs-idm49703456", "question_text": "Research indicates that the symptoms of OCD ________." }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 3, "ans_text": "physical complaints that cannot be explained medically" }, "bloom": null, "hl_context": "PTSD was listed among the anxiety disorders in previous DSM editions . In DSM - 5 , it is now listed among a group called Trauma-and-Stressor-Related Disorders . <hl> For a person to be diagnosed with PTSD , she must be exposed to , witness , or experience the details of a traumatic experience ( e . g . , a first responder ) , one that involves “ actual or threatened death , serious injury , or sexual violence ” ( APA , 2013 , p . 271 ) . <hl> These experiences can include such events as combat , threatened or actual physical attack , sexual assault , natural disasters , terrorist attacks , and automobile accidents . This criterion makes PTSD the only disorder listed in the DSM in which a cause ( extreme trauma ) is explicitly specified . <hl> Symptoms of PTSD include intrusive and distressing memories of the event , flashbacks ( states that can last from a few seconds to several days , during which the individual relives the event and behaves as if the event were occurring at that moment [ APA , 2013 ] ) , avoidance of stimuli connected to the event , persistently negative emotional states ( e . g . , fear , anger , guilt , and shame ) , feelings of detachment from others , irritability , proneness toward outbursts , and an exaggerated startle response ( jumpiness ) . <hl> For PTSD to be diagnosed , these symptoms must occur for at least one month .", "hl_sentences": "For a person to be diagnosed with PTSD , she must be exposed to , witness , or experience the details of a traumatic experience ( e . g . , a first responder ) , one that involves “ actual or threatened death , serious injury , or sexual violence ” ( APA , 2013 , p . 271 ) . Symptoms of PTSD include intrusive and distressing memories of the event , flashbacks ( states that can last from a few seconds to several days , during which the individual relives the event and behaves as if the event were occurring at that moment [ APA , 2013 ] ) , avoidance of stimuli connected to the event , persistently negative emotional states ( e . g . , fear , anger , guilt , and shame ) , feelings of detachment from others , irritability , proneness toward outbursts , and an exaggerated startle response ( jumpiness ) .", "question": { "cloze_format": "Symptoms of PTSD include all of the following except ________.", "normal_format": "Symptoms of PTSD include all of the following except what?", "question_choices": [ "intrusive thoughts or memories of a traumatic event", "avoidance of things that remind one of a traumatic event", "jumpiness", "physical complaints that cannot be explained medically" ], "question_id": "fs-idp78100160", "question_text": "Symptoms of PTSD include all of the following except ________." }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 0, "ans_text": "severity of the trauma" }, "bloom": null, "hl_context": "<hl> Of course , not everyone who experiences a traumatic event will go on to develop PTSD ; several factors strongly predict the development of PTSD : trauma experience , greater trauma severity , lack of immediate social support , and more subsequent life stress ( Brewin , Andrews , & Valentine , 2000 ) . <hl> Traumatic events that involve harm by others ( e . g . , combat , rape , and sexual molestation ) carry greater risk than do other traumas ( e . g . , natural disasters ) ( Kessler , Sonnega , Bromet , Hughes , & Nelson , 1995 ) . Factors that increase the risk of PTSD include female gender , low socioeconomic status , low intelligence , personal history of mental disorders , history of childhood adversity ( abuse or other trauma during childhood ) , and family history of mental disorders ( Brewin et al . , 2000 ) . Personality characteristics such as neuroticism and somatization ( the tendency to experience physical symptoms when one encounters stress ) have been shown to elevate the risk of PTSD ( Bramsen , Dirkzwager , & van der Ploeg , 2000 ) . People who experience childhood adversity and / or traumatic experiences during adulthood are at significantly higher risk of developing PTSD if they possess one or two short versions of a gene that regulates the neurotransmitter serotonin ( Xie et al . , 2009 ) . This suggests a possible diathesis-stress interpretation of PTSD : its development is influenced by the interaction of psychosocial and biological factors .", "hl_sentences": "Of course , not everyone who experiences a traumatic event will go on to develop PTSD ; several factors strongly predict the development of PTSD : trauma experience , greater trauma severity , lack of immediate social support , and more subsequent life stress ( Brewin , Andrews , & Valentine , 2000 ) .", "question": { "cloze_format": "___ elevates the risk for developing PTSD.", "normal_format": "Which of the following elevates the risk for developing PTSD?", "question_choices": [ "severity of the trauma", "frequency of the trauma", "high levels of intelligence", "social support" ], "question_id": "fs-idp64237440", "question_text": "Which of the following elevates the risk for developing PTSD?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 0, "ans_text": "periods of extreme elation and euphoria" }, "bloom": null, "hl_context": "<hl> difficulty concentrating and indecisiveness ; and <hl> <hl> psychomotor agitation ( the person is noticeably fidgety and jittery , demonstrated by behaviors like the inability to sit , pacing , hand-wringing , pulling or rubbing of the skin , clothing , or other objects ) or psychomotor retardation ( the person talks and moves slowly , for example , talking softly , very little , or in a monotone ); <hl> <hl> To receive a diagnosis of major depressive disorder , one must experience a total of five symptoms for at least a two-week period ; these symptoms must cause significant distress or impair normal functioning , and they must not be caused by substances or a medical condition . <hl> At least one of the two symptoms mentioned above must be present , plus any combination of the following symptoms ( APA , 2013 ): <hl> According to the DSM - 5 , the defining symptoms of major depressive disorder include “ depressed mood most of the day , nearly every day ” ( feeling sad , empty , hopeless , or appearing tearful to others ) , and loss of interest and pleasure in usual activities ( APA , 2013 ) . <hl> In addition to feeling overwhelmingly sad most of each day , people with depression will no longer show interest or enjoyment in activities that previously were gratifying , such as hobbies , sports , sex , social events , time spent with family , and so on . Friends and family members may notice that the person has completely abandoned previously enjoyed hobbies ; for example , an avid tennis player who develops major depressive disorder no longer plays tennis ( Rothschild , 1999 ) .", "hl_sentences": "difficulty concentrating and indecisiveness ; and psychomotor agitation ( the person is noticeably fidgety and jittery , demonstrated by behaviors like the inability to sit , pacing , hand-wringing , pulling or rubbing of the skin , clothing , or other objects ) or psychomotor retardation ( the person talks and moves slowly , for example , talking softly , very little , or in a monotone ); To receive a diagnosis of major depressive disorder , one must experience a total of five symptoms for at least a two-week period ; these symptoms must cause significant distress or impair normal functioning , and they must not be caused by substances or a medical condition . According to the DSM - 5 , the defining symptoms of major depressive disorder include “ depressed mood most of the day , nearly every day ” ( feeling sad , empty , hopeless , or appearing tearful to others ) , and loss of interest and pleasure in usual activities ( APA , 2013 ) .", "question": { "cloze_format": "Common symptoms of major depressive disorder include all of the following except ________.", "normal_format": "Common symptoms of major depressive disorder don't include which of the following?", "question_choices": [ "periods of extreme elation and euphoria", "difficulty concentrating and making decisions", "loss of interest or pleasure in usual activities", "psychomotor agitation and retardation" ], "question_id": "fs-idm231323552", "question_text": "Common symptoms of major depressive disorder include all of the following except ________." }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 2, "ans_text": "higher; lower" }, "bloom": null, "hl_context": "<hl> Contrary to popular belief , suicide rates peak during the springtime ( April and May ) , not during the holiday season or winter . <hl> In fact , suicide rates are generally lowest during the winter months ( Postolache et al . , 2010 ) . <hl> Suicide among males is 4 times higher than among females and accounts for 79 % of all suicides ; firearms are the most commonly used method of suicide for males , whereas poisoning is the most commonly used method for females ( CDC , 2012 ) . <hl>", "hl_sentences": "Contrary to popular belief , suicide rates peak during the springtime ( April and May ) , not during the holiday season or winter . Suicide among males is 4 times higher than among females and accounts for 79 % of all suicides ; firearms are the most commonly used method of suicide for males , whereas poisoning is the most commonly used method for females ( CDC , 2012 ) .", "question": { "cloze_format": "Suicide rates are ________ among men than among women, and they are ________ during the winter holiday season than during the spring months.", "normal_format": "How are the rates of suicide among men than among women, and how are the rates of suicide during the winter holiday season than during the spring months?", "question_choices": [ "higher; higher", "lower; lower", "higher; lower", "lower; higher" ], "question_id": "fs-idm127496192", "question_text": "Suicide rates are ________ among men than among women, and they are ________ during the winter holiday season than during the spring months." }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 0, "ans_text": "a delusion" }, "bloom": null, "hl_context": "<hl> Delusions are beliefs that are contrary to reality and are firmly held even in the face of contradictory evidence . <hl> Many of us hold beliefs that some would consider odd , but a delusion is easily identified because it is clearly absurd . A person with schizophrenia may believe that his mother is plotting with the FBI to poison his coffee , or that his neighbor is an enemy spy who wants to kill him . These kinds of delusions are known as paranoid delusions , which involve the ( false ) belief that other people or agencies are plotting to harm the person . People with schizophrenia also may hold grandiose delusions , beliefs that one holds special power , unique knowledge , or is extremely important . For example , the person who claims to be Jesus Christ , or who claims to have knowledge going back 5,000 years , or who claims to be a great philosopher is experiencing grandiose delusions . Other delusions include the belief that one ’ s thoughts are being removed ( thought withdrawal ) or thoughts have been placed inside one ’ s head ( thought insertion ) . Another type of delusion is somatic delusion , which is the belief that something highly abnormal is happening to one ’ s body ( e . g . , that one ’ s kidneys are being eaten by cockroaches ) .", "hl_sentences": "Delusions are beliefs that are contrary to reality and are firmly held even in the face of contradictory evidence .", "question": { "cloze_format": "Clifford falsely believes that the police have planted secret cameras in his home to monitor his every movement. Clifford’s belief is an example of ________.", "normal_format": "Clifford falsely believes that the police have planted secret cameras in his home to monitor his every movement. Clifford’s belief is an example of which of the following?", "question_choices": [ "a delusion", "a hallucination", "tangentiality", "a negative symptom" ], "question_id": "fs-idm38213936", "question_text": "Clifford falsely believes that the police have planted secret cameras in his home to monitor his every movement. Clifford’s belief is an example of ________." }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 2, "ans_text": "if they were raised in a disturbed adoptive home environment" }, "bloom": null, "hl_context": "Although adoption studies have supported the hypothesis that genetic factors contribute to schizophrenia , they have also demonstrated that the disorder most likely arises from a combination of genetic and environmental factors , rather than just genes themselves . For example , investigators in one study examined the rates of schizophrenia among 303 adoptees ( Tienari et al . , 2004 ) . A total of 145 of the adoptees had biological mothers with schizophrenia ; these adoptees constituted the high genetic risk group . The other 158 adoptees had mothers with no psychiatric history ; these adoptees composed the low genetic risk group . The researchers managed to determine whether the adoptees ’ families were either healthy or disturbed . For example , the adoptees were considered to be raised in a disturbed family environment if the family exhibited a lot of criticism , conflict , and a lack of problem-solving skills . <hl> The findings revealed that adoptees whose mothers had schizophrenia ( high genetic risk ) and who had been raised in a disturbed family environment were much more likely to develop schizophrenia or another psychotic disorder ( 36.8 % ) than were adoptees whose biological mothers had schizophrenia but who had been raised in a healthy environment ( 5.8 % ) , or than adoptees with a low genetic risk who were raised in either a disturbed ( 5.3 % ) or healthy ( 4.8 % ) environment . <hl> Because the adoptees who were at high genetic risk were likely to develop schizophrenia only if they were raised in a disturbed home environment , this study supports a diathesis-stress interpretation of schizophrenia — both genetic vulnerability and environmental stress are necessary for schizophrenia to develop , genes alone do not show the complete picture .", "hl_sentences": "The findings revealed that adoptees whose mothers had schizophrenia ( high genetic risk ) and who had been raised in a disturbed family environment were much more likely to develop schizophrenia or another psychotic disorder ( 36.8 % ) than were adoptees whose biological mothers had schizophrenia but who had been raised in a healthy environment ( 5.8 % ) , or than adoptees with a low genetic risk who were raised in either a disturbed ( 5.3 % ) or healthy ( 4.8 % ) environment .", "question": { "cloze_format": "A study of adoptees whose biological mothers had schizophrenia found that the adoptees were most likely to develop schizophrenia ________.", "normal_format": "A study of adoptees whose biological mothers had schizophrenia found that the adoptees were most likely to develop schizophrenia if which of the following condition was met?", "question_choices": [ "if their childhood friends later developed schizophrenia", "if they abused drugs during adolescence", "if they were raised in a disturbed adoptive home environment", "regardless of whether they were raised in a healthy or disturbed home environment" ], "question_id": "fs-idp14872640", "question_text": "A study of adoptees whose biological mothers had schizophrenia found that the adoptees were most likely to develop schizophrenia ________." }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 1, "ans_text": "memory loss following stress" }, "bloom": null, "hl_context": "Amnesia refers to the partial or total forgetting of some experience or event . <hl> An individual with dissociative amnesia is unable to recall important personal information , usually following an extremely stressful or traumatic experience such as combat , natural disasters , or being the victim of violence . <hl> <hl> The memory impairments are not caused by ordinary forgetting . <hl> Some individuals with dissociative amnesia will also experience dissociative fugue ( from the word “ to flee ” in French ) , whereby they suddenly wander away from their home , experience confusion about their identity , and sometimes even adopt a new identity ( Cardeña & Gleaves , 2006 ) . Most fugue episodes last only a few hours or days , but some can last longer . One study of residents in communities in upstate New York reported that about 1.8 % experienced dissociative amnesia in the previous year ( Johnson , Cohen , Kasen , & Brook , 2006 ) .", "hl_sentences": "An individual with dissociative amnesia is unable to recall important personal information , usually following an extremely stressful or traumatic experience such as combat , natural disasters , or being the victim of violence . The memory impairments are not caused by ordinary forgetting .", "question": { "cloze_format": "Dissociative amnesia involves ________.", "normal_format": "What does dissociative amnesia involve?", "question_choices": [ "memory loss following head trauma", "memory loss following stress", "feeling detached from the self", "feeling detached from the world" ], "question_id": "fs-idp36529360", "question_text": "Dissociative amnesia involves ________." }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 3, "ans_text": "different personalities" }, "bloom": null, "hl_context": "<hl> By far , the most well-known dissociative disorder is dissociative identity disorder ( formerly called multiple personality disorder ) . <hl> <hl> People with dissociative identity disorder exhibit two or more separate personalities or identities , each well-defined and distinct from one another . <hl> They also experience memory gaps for the time during which another identity is in charge ( e . g . , one might find unfamiliar items in her shopping bags or among her possessions ) , and in some cases may report hearing voices , such as a child ’ s voice or the sound of somebody crying ( APA , 2013 ) . The study of upstate New York residents mentioned above ( Johnson et al . , 2006 ) reported that 1.5 % of their sample experienced symptoms consistent with dissociative identity disorder in the previous year .", "hl_sentences": "By far , the most well-known dissociative disorder is dissociative identity disorder ( formerly called multiple personality disorder ) . People with dissociative identity disorder exhibit two or more separate personalities or identities , each well-defined and distinct from one another .", "question": { "cloze_format": "Dissociative identity disorder mainly involves ________.", "normal_format": "What does dissociative identity disorder mainly involve?", "question_choices": [ "depersonalization", "derealization", "schizophrenia", "different personalities" ], "question_id": "fs-idm54290272", "question_text": "Dissociative identity disorder mainly involves ________." }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 2, "ans_text": "are impulsive and unpredictable" }, "bloom": null, "hl_context": "<hl> Genetic factors appear to be important in the development of borderline personality disorder . <hl> <hl> For example , core personality traits that characterize this disorder , such as impulsivity and emotional instability , show a high degree of heritability ( Livesley , 2008 ) . <hl> Also , the rates of borderline personality disorder among relatives of people with this disorder have been found to be as high as 24.9 % ( White , Gunderson , Zanarani , & Hudson , 2003 ) . Individuals with borderline personality disorder report experiencing childhood physical , sexual , and / or emotional abuse at rates far greater than those observed in the general population ( Afifi et al . , 2010 ) , indicating that environmental factors are also crucial . These findings would suggest that borderline personality disorder may be determined by an interaction between genetic factors and adverse environmental experiences . Consistent with this hypothesis , one study found that the highest rates of borderline personality disorder were among individuals with a borderline temperament ( characterized by high novelty seeking and high harm-avoidance ) and those who experienced childhood abuse and / or neglect ( Joyce et al . , 2003 ) . The “ borderline ” in borderline personality disorder was originally coined in the late 1930s in an effort to describe patients who appeared anxious , but were prone to brief psychotic experiences — that is , patients who were thought to be literally on the borderline between anxiety and psychosis ( Freeman , Stone , Martin , & Reinecke , 2005 ) . Today , borderline personality disorder has a completely different meaning . <hl> Borderline personality disorder is characterized chiefly by instability in interpersonal relationships , self-image , and mood , as well as marked impulsivity ( APA , 2013 ) . <hl> People with borderline personality disorder cannot tolerate the thought of being alone and will make frantic efforts ( including making suicidal gestures and engaging in self-mutilation ) to avoid abandonment or separation ( whether real or imagined ) . Their relationships are intense and unstable ; for example , a lover may be idealized early in a relationship , but then later vilified at the slightest sign she appears to no longer show interest . These individuals have an unstable view of self and , thus , might suddenly display a shift in personal attitudes , interests , career plans , and choice of friends . For example , a law school student may , despite having invested tens of thousands of dollars toward earning a law degree and despite having performed well in the program , consider dropping out and pursuing a career in another field . People with borderline personality disorder may be highly impulsive and may engage in reckless and self-destructive behaviors such as excessive gambling , spending money irresponsibly , substance abuse , engaging in unsafe sex , and reckless driving . They sometimes show intense and inappropriate anger that they have difficulty controlling , and they can be moody , sarcastic , bitter , and verbally abusive . The DSM - 5 recognizes 10 personality disorders , organized into 3 different clusters . Cluster A disorders include paranoid personality disorder , schizoid personality disorder , and schizotypal personality disorder . People with these disorders display a personality style that is odd or eccentric . <hl> Cluster B disorders include antisocial personality disorder , histrionic personality disorder , narcissistic personality disorder , and borderline personality disorder . <hl> <hl> People with these disorders usually are impulsive , overly dramatic , highly emotional , and erratic . <hl> Cluster C disorders include avoidant personality disorder , dependent personality disorder , and obsessive-compulsive personality disorder ( which is not the same thing as obsessive-compulsive disorder ) . People with these disorders often appear to be nervous and fearful . Table 15.2 provides a description of each of the DSM - 5 personality disorders :", "hl_sentences": "Genetic factors appear to be important in the development of borderline personality disorder . For example , core personality traits that characterize this disorder , such as impulsivity and emotional instability , show a high degree of heritability ( Livesley , 2008 ) . Borderline personality disorder is characterized chiefly by instability in interpersonal relationships , self-image , and mood , as well as marked impulsivity ( APA , 2013 ) . Cluster B disorders include antisocial personality disorder , histrionic personality disorder , narcissistic personality disorder , and borderline personality disorder . People with these disorders usually are impulsive , overly dramatic , highly emotional , and erratic .", "question": { "cloze_format": "People with borderline personality disorder often ________.", "normal_format": "What do people with borderline personality disorder often do?", "question_choices": [ "try to be the center of attention", "are shy and withdrawn", "are impulsive and unpredictable", "tend to accomplish goals through cruelty" ], "question_id": "fs-idm149440768", "question_text": "People with borderline personality disorder often ________." }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 0, "ans_text": "emotional deficits" }, "bloom": null, "hl_context": "Those with antisocial tendencies do not seem to experience emotions the way most other people do . These individuals fail to show fear in response to environment cues that signal punishment , pain , or noxious stimulation . For instance , they show less skin conductance ( sweatiness on hands ) in anticipation of electric shock than do people without antisocial tendencies ( Hare , 1965 ) . Skin conductance is controlled by the sympathetic nervous system and is used to assess autonomic nervous system functioning . When the sympathetic nervous system is active , people become aroused and anxious , and sweat gland activity increases . Thus , increased sweat gland activity , as assessed through skin conductance , is taken as a sign of arousal or anxiety . <hl> For those with antisocial personality disorder , a lack of skin conductance may indicate the presence of characteristics such as emotional deficits and impulsivity that underlie the propensity for antisocial behavior and negative social relationships ( Fung et al . , 2005 ) . <hl> <hl> People with antisocial personality disorder seem to view the world as self-serving and unkind . <hl> They seem to think that they should use whatever means necessary to get by in life . They tend to view others not as living , thinking , feeling beings , but rather as pawns to be used or abused for a specific purpose . They often have an over-inflated sense of themselves and can appear extremely arrogant . They frequently display superficial charm ; for example , without really meaning it they might say exactly what they think another person wants to hear . <hl> They lack empathy : they are incapable of understanding the emotional point-of-view of others . <hl> People with this disorder may become involved in illegal enterprises , show cruelty toward others , leave their jobs with no plans to obtain another job , have multiple sexual partners , repeatedly get into fights with others , and show reckless disregard for themselves and others ( e . g . , repeated arrests for driving while intoxicated ) ( APA , 2013 ) . <hl> According to the DSM - 5 , the individual with antisocial personality disorder ( sometimes referred to as psychopathy ) shows no regard at all for other people ’ s rights or feelings . <hl> This lack of regard is exhibited a number of ways and can include repeatedly performing illegal acts , lying to or conning others , impulsivity and recklessness , irritability and aggressiveness toward others , and failure to act in a responsible way ( e . g . , leaving debts unpaid ) ( APA , 2013 ) . The worst part about antisocial personality disorder , however , is that people with this disorder have no remorse over one ’ s misdeeds ; these people will hurt , manipulate , exploit , and abuse others and not feel any guilt . Signs of this disorder can emerge early in life ; however , a person must be at least 18 years old to be diagnosed with antisocial personality disorder .", "hl_sentences": "For those with antisocial personality disorder , a lack of skin conductance may indicate the presence of characteristics such as emotional deficits and impulsivity that underlie the propensity for antisocial behavior and negative social relationships ( Fung et al . , 2005 ) . People with antisocial personality disorder seem to view the world as self-serving and unkind . They lack empathy : they are incapable of understanding the emotional point-of-view of others . According to the DSM - 5 , the individual with antisocial personality disorder ( sometimes referred to as psychopathy ) shows no regard at all for other people ’ s rights or feelings .", "question": { "cloze_format": "Antisocial personality disorder is associated with ________.", "normal_format": "What is antisocial personality disorder associated with?", "question_choices": [ "emotional deficits", "memory deficits", "parental overprotection", "increased empathy" ], "question_id": "fs-idm133474576", "question_text": "Antisocial personality disorder is associated with ________." }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 2, "ans_text": "restricted and fixated interest" }, "bloom": null, "hl_context": "A child with ADHD shows a constant pattern of inattention and / or hyperactive and impulsive behavior that interferes with normal functioning ( APA , 2013 ) . Some of the signs of inattention include great difficulty with and avoidance of tasks that require sustained attention ( such as conversations or reading ) , failure to follow instructions ( often resulting in failure to complete school work and other duties ) , disorganization ( difficulty keeping things in order , poor time management , sloppy and messy work ) , lack of attention to detail , becoming easily distracted , and forgetfulness . <hl> Hyperactivity is characterized by excessive movement , and includes fidgeting or squirming , leaving one ’ s seat in situations when remaining seated is expected , having trouble sitting still ( e . g . , in a restaurant ) , running about and climbing on things , blurting out responses before another person ’ s question or statement has been completed , difficulty waiting one ’ s turn for something , and interrupting and intruding on others . <hl> Frequently , the hyperactive child comes across as noisy and boisterous . The child ’ s behavior is hasty , impulsive , and seems to occur without much forethought ; these characteristics may explain why adolescents and young adults diagnosed with ADHD receive more traffic tickets and have more automobile accidents than do others ( Thompson , Molina , Pelham , & Gnagy , 2007 ) . <hl> Diego likely has attention deficit / hyperactivity disorder ( ADHD ) . <hl> The symptoms of this disorder were first described by Hans Hoffman in the 1920s . <hl> While taking care of his son while his wife was in the hospital giving birth to a second child , Hoffman noticed that the boy had trouble concentrating on his homework , had a short attention span , and had to repeatedly go over easy homework to learn the material ( Jellinek & Herzog , 1999 ) . <hl> <hl> Later , it was discovered that many hyperactive children — those who are fidgety , restless , socially disruptive , and have trouble with impulse control — also display short attention spans , problems with concentration , and distractibility . <hl> By the 1970s , it had become clear that many children who display attention problems often also exhibit signs of hyperactivity . In recognition of such findings , the DSM-III ( published in 1980 ) included a new disorder : attention deficit disorder with and without hyperactivity , now known as attention deficit / hyperactivity disorder ( ADHD ) .", "hl_sentences": "Hyperactivity is characterized by excessive movement , and includes fidgeting or squirming , leaving one ’ s seat in situations when remaining seated is expected , having trouble sitting still ( e . g . , in a restaurant ) , running about and climbing on things , blurting out responses before another person ’ s question or statement has been completed , difficulty waiting one ’ s turn for something , and interrupting and intruding on others . Diego likely has attention deficit / hyperactivity disorder ( ADHD ) . While taking care of his son while his wife was in the hospital giving birth to a second child , Hoffman noticed that the boy had trouble concentrating on his homework , had a short attention span , and had to repeatedly go over easy homework to learn the material ( Jellinek & Herzog , 1999 ) . Later , it was discovered that many hyperactive children — those who are fidgety , restless , socially disruptive , and have trouble with impulse control — also display short attention spans , problems with concentration , and distractibility .", "question": { "cloze_format": "___ is not a primary characteristic of ADHD.", "normal_format": "Which of the following is not a primary characteristic of ADHD?", "question_choices": [ "short attention span", "difficulty concentrating and distractibility", "restricted and fixated interest", "excessive fidgeting and squirming" ], "question_id": "fs-idp35048288", "question_text": "Which of the following is not a primary characteristic of ADHD?" }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 1, "ans_text": "difficulty relating to others" }, "bloom": null, "hl_context": "<hl> Autism spectrum disorder is probably the most misunderstood and puzzling of the neurodevelopmental disorders . <hl> Children with this disorder show signs of significant disturbances in three main areas : ( a ) deficits in social interaction , ( b ) deficits in communication , and ( c ) repetitive patterns of behavior or interests . These disturbances appear early in life and cause serious impairments in functioning ( APA , 2013 ) . The child with autism spectrum disorder might exhibit deficits in social interaction by not initiating conversations with other children or turning their head away when spoken to . These children do not make eye contact with others and seem to prefer playing alone rather than with others . In a certain sense , it is almost as though these individuals live in a personal and isolated social world others are simply not privy to or able to penetrate . <hl> Communication deficits can range from a complete lack of speech , to one word responses ( e . g . , saying “ Yes ” or “ No ” when replying to questions or statements that require additional elaboration ) , to echoed speech ( e . g . , parroting what another person says , either immediately or several hours or even days later ) , to difficulty maintaining a conversation because of an inability to reciprocate others ’ comments . <hl> These deficits can also include problems in using and understanding nonverbal cues ( e . g . , facial expressions , gestures , and postures ) that facilitate normal communication .", "hl_sentences": "Autism spectrum disorder is probably the most misunderstood and puzzling of the neurodevelopmental disorders . Communication deficits can range from a complete lack of speech , to one word responses ( e . g . , saying “ Yes ” or “ No ” when replying to questions or statements that require additional elaboration ) , to echoed speech ( e . g . , parroting what another person says , either immediately or several hours or even days later ) , to difficulty maintaining a conversation because of an inability to reciprocate others ’ comments .", "question": { "cloze_format": "One of the primary characteristics of autism spectrum disorder is ________.", "normal_format": "What is one of the primary characteristics of autism spectrum disorder?", "question_choices": [ "bed-wetting", "difficulty relating to others", "short attention span", "intense and inappropriate interest in others" ], "question_id": "fs-idp93539616", "question_text": "One of the primary characteristics of autism spectrum disorder is ________." }, "references_are_paraphrase": null } ]
15
15.1 What Are Psychological Disorders? Learning Objectives By the end of this section, you will be able to: Understand the problems inherent in defining the concept of psychological disorder Describe what is meant by harmful dysfunction Identify the formal criteria that thoughts, feelings, and behaviors must meet to be considered abnormal and, thus, symptomatic of a psychological disorder A psychological disorder is a condition characterized by abnormal thoughts, feelings, and behaviors. Psychopathology is the study of psychological disorders, including their symptoms, etiology (i.e., their causes), and treatment. The term psychopathology can also refer to the manifestation of a psychological disorder. Although consensus can be difficult, it is extremely important for mental health professionals to agree on what kinds of thoughts, feelings, and behaviors are truly abnormal in the sense that they genuinely indicate the presence of psychopathology. Certain patterns of behavior and inner experience can easily be labeled as abnormal and clearly signify some kind of psychological disturbance. The person who washes his hands 40 times per day and the person who claims to hear the voices of demons exhibit behaviors and inner experiences that most would regard as abnormal: beliefs and behaviors that suggest the existence of a psychological disorder. But, consider the nervousness a young man feels when talking to attractive women or the loneliness and longing for home a freshman experiences during her first semester of college—these feelings may not be regularly present, but they fall in the range of normal. So, what kinds of thoughts, feelings, and behaviors represent a true psychological disorder? Psychologists work to distinguish psychological disorders from inner experiences and behaviors that are merely situational, idiosyncratic, or unconventional. Definition of a Psychological Disorder Perhaps the simplest approach to conceptualizing psychological disorders is to label behaviors, thoughts, and inner experiences that are atypical, distressful, dysfunctional, and sometimes even dangerous, as signs of a disorder. For example, if you ask a classmate for a date and you are rejected, you probably would feel a little dejected. Such feelings would be normal. If you felt extremely depressed—so much so that you lost interest in activities, had difficulty eating or sleeping, felt utterly worthless, and contemplated suicide—your feelings would be atypical , would deviate from the norm, and could signify the presence of a psychological disorder. Just because something is atypical, however, does not necessarily mean it is disordered. For example, only about 4% of people in the United States have red hair, so red hair is considered an atypical characteristic ( Figure 15.2 ), but it is not considered disordered, it’s just unusual. And it is less unusual in Scotland, where approximately 13% of the population has red hair (“DNA Project Aims,” 2012). As you will learn, some disorders, although not exactly typical, are far from atypical, and the rates in which they appear in the population are surprisingly high. If we can agree that merely being atypical is an insufficient criterion for a having a psychological disorder, is it reasonable to consider behavior or inner experiences that differ from widely expected cultural values or expectations as disordered? Using this criterion, a woman who walks around a subway platform wearing a heavy winter coat in July while screaming obscenities at strangers may be considered as exhibiting symptoms of a psychological disorder. Her actions and clothes violate socially accepted rules governing appropriate dress and behavior; these characteristics are atypical. Cultural Expectations Violating cultural expectations is not, in and of itself, a satisfactory means of identifying the presence of a psychological disorder. Since behavior varies from one culture to another, what may be expected and considered appropriate in one culture may not be viewed as such in other cultures. For example, returning a stranger’s smile is expected in the United States because a pervasive social norm dictates that we reciprocate friendly gestures. A person who refuses to acknowledge such gestures might be considered socially awkward—perhaps even disordered—for violating this expectation. However, such expectations are not universally shared. Cultural expectations in Japan involve showing reserve, restraint, and a concern for maintaining privacy around strangers. Japanese people are generally unresponsive to smiles from strangers (Patterson et al., 2007). Eye contact provides another example. In the United States and Europe, eye contact with others typically signifies honesty and attention. However, most Latin-American, Asian, and African cultures interpret direct eye contact as rude, confrontational, and aggressive (Pazain, 2010). Thus, someone who makes eye contact with you could be considered appropriate and respectful or brazen and offensive, depending on your culture ( Figure 15.3 ). Hallucinations (seeing or hearing things that are not physically present) in Western societies is a violation of cultural expectations, and a person who reports such inner experiences is readily labeled as psychologically disordered. In other cultures, visions that, for example, pertain to future events may be regarded as normal experiences that are positively valued (Bourguignon, 1970). Finally, it is important to recognize that cultural norms change over time: what might be considered typical in a society at one time may no longer be viewed this way later, similar to how fashion trends from one era may elicit quizzical looks decades later—imagine how a headband, legwarmers, and the big hair of the 1980s would go over on your campus today. Dig Deeper The Myth of Mental Illness In the 1950s and 1960s, the concept of mental illness was widely criticized. One of the major criticisms focused on the notion that mental illness was a “myth that justifies psychiatric intervention in socially disapproved behavior” (Wakefield, 1992). Thomas Szasz (1960), a noted psychiatrist, was perhaps the biggest proponent of this view. Szasz argued that the notion of mental illness was invented by society (and the mental health establishment) to stigmatize and subjugate people whose behavior violates accepted social and legal norms. Indeed, Szasz suggested that what appear to be symptoms of mental illness are more appropriately characterized as “problems in living” (Szasz, 1960). In his 1961 book, The Myth of Mental Illness: Foundations of a Theory of Personal Conduct , Szasz expressed his disdain for the concept of mental illness and for the field of psychiatry in general (Oliver, 2006). The basis for Szasz’s attack was his contention that detectable abnormalities in bodily structures and functions (e.g., infections and organ damage or dysfunction) represent the defining features of genuine illness or disease, and because symptoms of purported mental illness are not accompanied by such detectable abnormalities, so-called psychological disorders are not disorders at all. Szasz (1961/2010) proclaimed that “disease or illness can only affect the body; hence, there can be no mental illness” (p. 267). Today, we recognize the extreme level of psychological suffering experienced by people with psychological disorders: the painful thoughts and feelings they experience, the disordered behavior they demonstrate, and the levels of distress and impairment they exhibit. This makes it very difficult to deny the reality of mental illness. However controversial Szasz’s views and those of his supporters might have been, they have influenced the mental health community and society in several ways. First, lay people, politicians, and professionals now often refer to mental illness as mental health “problems,” implicitly acknowledging the “problems in living” perspective Szasz described (Buchanan-Barker & Barker, 2009). Also influential was Szasz’s view of homosexuality. Szasz was perhaps the first psychiatrist to openly challenge the idea that homosexuality represented a form of mental illness or disease (Szasz, 1965). By challenging the idea that homosexuality represented a form a mental illness, Szasz helped pave the way for the social and civil rights that gay and lesbian people now have (Barker, 2010). His work also inspired legal changes that protect the rights of people in psychiatric institutions and allow such individuals a greater degree of influence and responsibility over their lives (Buchanan-Barker & Barker, 2009). Harmful Dysfunction If none of the criteria discussed so far is adequate by itself to define the presence of a psychological disorder, how can a disorder be conceptualized? Many efforts have been made to identify the specific dimensions of psychological disorders, yet none is entirely satisfactory. No universal definition of psychological disorder exists that can apply to all situations in which a disorder is thought to be present (Zachar & Kendler, 2007). However, one of the more influential conceptualizations was proposed by Wakefield (1992), who defined psychological disorder as a harmful dysfunction . Wakefield argued that natural internal mechanisms—that is, psychological processes honed by evolution, such as cognition, perception, and learning—have important functions, such as enabling us to experience the world the way others do and to engage in rational thought, problem solving, and communication. For example, learning allows us to associate a fear with a potential danger in such a way that the intensity of fear is roughly equal to the degree of actual danger. Dysfunction occurs when an internal mechanism breaks down and can no longer perform its normal function. But, the presence of a dysfunction by itself does not determine a disorder. The dysfunction must be harmful in that it leads to negative consequences for the individual or for others, as judged by the standards of the individual’s culture. The harm may include significant internal anguish (e.g., high levels of anxiety or depression) or problems in day-to-day living (e.g., in one’s social or work life). To illustrate, Janet has an extreme fear of spiders. Janet’s fear might be considered a dysfunction in that it signals that the internal mechanism of learning is not working correctly (i.e., a faulty process prevents Janet from appropriately associating the magnitude of her fear with the actual threat posed by spiders). Janet’s fear of spiders has a significant negative influence on her life: she avoids all situations in which she suspects spiders to be present (e.g., the basement or a friend’s home), and she quit her job last month because she saw a spider in the restroom at work and is now unemployed. According to the harmful dysfunction model, Janet’s condition would signify a disorder because (a) there is a dysfunction in an internal mechanism, and (b) the dysfunction has resulted in harmful consequences. Similar to how the symptoms of physical illness reflect dysfunctions in biological processes, the symptoms of psychological disorders presumably reflect dysfunctions in mental processes. The internal mechanism component of this model is especially appealing because it implies that disorders may occur through a breakdown of biological functions that govern various psychological processes, thus supporting contemporary neurobiological models of psychological disorders (Fabrega, 2007). The American Psychiatric Association (APA) Definition Many of the features of the harmful dysfunction model are incorporated in a formal definition of psychological disorder developed by the American Psychiatric Association (APA). According to the APA (2013), a psychological disorder is a condition that is said to consist of the following: There are significant disturbances in thoughts, feelings, and behaviors . A person must experience inner states (e.g., thoughts and/or feelings) and exhibit behaviors that are clearly disturbed—that is, unusual, but in a negative, self-defeating way. Often, such disturbances are troubling to those around the individual who experiences them. For example, an individual who is uncontrollably preoccupied by thoughts of germs spends hours each day bathing, has inner experiences, and displays behaviors that most would consider atypical and negative (disturbed) and that would likely be troubling to family members. The disturbances reflect some kind of biological, psychological, or developmental dysfunction . Disturbed patterns of inner experiences and behaviors should reflect some flaw (dysfunction) in the internal biological, psychological, and developmental mechanisms that lead to normal, healthy psychological functioning. For example, the hallucinations observed in schizophrenia could be a sign of brain abnormalities. The disturbances lead to significant distress or disability in one’s life . A person’s inner experiences and behaviors are considered to reflect a psychological disorder if they cause the person considerable distress, or greatly impair his ability to function as a normal individual (often referred to as functional impairment, or occupational and social impairment). As an illustration, a person’s fear of social situations might be so distressing that it causes the person to avoid all social situations (e.g., preventing that person from being able to attend class or apply for a job). The disturbances do not reflect expected or culturally approved responses to certain events . Disturbances in thoughts, feelings, and behaviors must be socially unacceptable responses to certain events that often happen in life. For example, it is perfectly natural (and expected) that a person would experience great sadness and might wish to be left alone following the death of a close family member. Because such reactions are in some ways culturally expected, the individual would not be assumed to signify a mental disorder. Some believe that there is no essential criterion or set of criteria that can definitively distinguish all cases of disorder from nondisorder (Lilienfeld & Marino, 1999). In truth, no single approach to defining a psychological disorder is adequate by itself, nor is there universal agreement on where the boundary is between disordered and not disordered. From time to time we all experience anxiety, unwanted thoughts, and moments of sadness; our behavior at other times may not make much sense to ourselves or to others. These inner experiences and behaviors can vary in their intensity, but are only considered disordered when they are highly disturbing to us and/or others, suggest a dysfunction in normal mental functioning, and are associated with significant distress or disability in social or occupational activities. 15.10 Personality Disorders Learning Objectives By the end of this section, you will be able to: Describe the nature of personality disorders and how they differ from other disorders List and distinguish between the three clusters of personality disorders Identify the basic features of borderline personality disorder and antisocial personality disorder, and the factors that are important in the etiology of both The term personality refers loosely to one’s stable, consistent, and distinctive way of thinking about, feeling, acting, and relating to the world. People with personality disorders exhibit a personality style that differs markedly from the expectations of their culture, is pervasive and inflexible, begins in adolescence or early adulthood, and causes distress or impairment (APA, 2013). Generally, individuals with these disorders exhibit enduring personality styles that are extremely troubling and often create problems for them and those with whom they come into contact. Their maladaptive personality styles frequently bring them into conflict with others, disrupt their ability to develop and maintain social relationships, and prevent them from accomplishing realistic life goals. The DSM-5 recognizes 10 personality disorders, organized into 3 different clusters. Cluster A disorders include paranoid personality disorder , schizoid personality disorder , and schizotypal personality disorder . People with these disorders display a personality style that is odd or eccentric. Cluster B disorders include antisocial personality disorder, histrionic personality disorder , narcissistic personality disorder , and borderline personality disorder. People with these disorders usually are impulsive, overly dramatic, highly emotional, and erratic. Cluster C disorders include avoidant personality disorder , dependent personality disorder , and obsessive-compulsive personality disorder (which is not the same thing as obsessive-compulsive disorder). People with these disorders often appear to be nervous and fearful. Table 15.2 provides a description of each of the DSM-5 personality disorders: DSM-5 Personality Disorder Description Cluster Paranoid harbors a pervasive and unjustifiable suspiciousness and mistrust of others; reluctant to confide in or become close to others; reads hidden demeaning or threatening meaning into benign remarks or events; takes offense easily and bears grudges; not due to schizophrenia or other psychotic disorders A Schizoid lacks interest and desire to form relationships with others; aloof and shows emotional coldness and detachment; indifferent to approval or criticism of others; lacks close friends or confidants; not due to schizophrenia or other psychotic disorders, not an autism spectrum disorder A Schizotypal exhibits eccentricities in thought, perception, emotion, speech, and behavior; shows suspiciousness or paranoia; has unusual perceptual experiences; speech is often idiosyncratic; displays inappropriate emotions; lacks friends or confidants; not due to schizophrenia or other psychotic disorder, or to autism spectrum disorder A Antisocial continuously violates the rights of others; history of antisocial tendencies prior to age 15; often lies, fights, and has problems with the law; impulsive and fails to think ahead; can be deceitful and manipulative in order to gain profit or pleasure; irresponsible and often fails to hold down a job or pay financial debts; lacks feelings for others and remorse over misdeeds B Histrionic excessively overdramatic, emotional, and theatrical; feels uncomfortable when not the center of others’ attention; behavior is often inappropriately seductive or provocative; speech is highly emotional but often vague and diffuse; emotions are shallow and often shift rapidly; may alienate friends with demands for constant attention B Narcissistic overinflated and unjustified sense of self-importance and preoccupied with fantasies of success; believes he is entitled to special treatment from others; shows arrogant attitudes and behaviors; takes advantage of others; lacks empathy B Borderline unstable in self-image, mood, and behavior; cannot tolerate being alone and experiences chronic feelings of emptiness; unstable and intense relationships with others; behavior is impulsive, unpredictable, and sometimes self-damaging; shows inappropriate and intense anger; makes suicidal gestures B Avoidant socially inhibited and oversensitive to negative evaluation; avoids occupations that involve interpersonal contact because of fears of criticism or rejection; avoids relationships with others unless guaranteed to be accepted unconditionally; feels inadequate and views self as socially inept and unappealing; unwilling to take risks or engage in new activities if they may prove embarrassing C Dependent allows others to take over and run her life; is submissive, clingy, and fears separation; cannot make decisions without advice and reassurance from others; lacks self-confidence; cannot do things on her own; feels uncomfortable or helpless when alone C Obsessive-Compulsive pervasive need for perfectionism that interferes with the ability to complete tasks; preoccupied with details, rules, order, and schedules; excessively devoted to work at the expense of leisure and friendships; rigid, inflexible, and stubborn; insists things be done his way; miserly with money C Table 15.2 DSM-5 Personality Disorders Slightly over 9% of the U.S. population suffers from a personality disorder, with avoidant and schizoid personality disorders the most frequent (Lezenweger, Lane, Loranger, & Kessler, 2007). Two of these personality disorders, borderline personality disorder and antisocial personality disorder, are regarded by many as especially problematic. Borderline Personality Disorder The “borderline” in borderline personality disorder was originally coined in the late 1930s in an effort to describe patients who appeared anxious, but were prone to brief psychotic experiences—that is, patients who were thought to be literally on the borderline between anxiety and psychosis (Freeman, Stone, Martin, & Reinecke, 2005). Today, borderline personality disorder has a completely different meaning. Borderline personality disorder is characterized chiefly by instability in interpersonal relationships, self-image, and mood, as well as marked impulsivity (APA, 2013). People with borderline personality disorder cannot tolerate the thought of being alone and will make frantic efforts (including making suicidal gestures and engaging in self-mutilation) to avoid abandonment or separation (whether real or imagined). Their relationships are intense and unstable; for example, a lover may be idealized early in a relationship, but then later vilified at the slightest sign she appears to no longer show interest. These individuals have an unstable view of self and, thus, might suddenly display a shift in personal attitudes, interests, career plans, and choice of friends. For example, a law school student may, despite having invested tens of thousands of dollars toward earning a law degree and despite having performed well in the program, consider dropping out and pursuing a career in another field. People with borderline personality disorder may be highly impulsive and may engage in reckless and self-destructive behaviors such as excessive gambling, spending money irresponsibly, substance abuse, engaging in unsafe sex, and reckless driving. They sometimes show intense and inappropriate anger that they have difficulty controlling, and they can be moody, sarcastic, bitter, and verbally abusive. The prevalence of borderline personality disorder in the U.S. population is estimated to be around 1.4% (Lezenweger et al., 2007), but the rates are higher among those who use mental health services; approximately 10% of mental health outpatients and 20% of psychiatric inpatients meet the criteria for diagnosis (APA, 2013). Additionally, borderline personality disorder is comorbid with anxiety, mood, and substance use disorders (Lezenweger et al., 2007). Biological Basis for Borderline Personality Disorder Genetic factors appear to be important in the development of borderline personality disorder. For example, core personality traits that characterize this disorder, such as impulsivity and emotional instability, show a high degree of heritability (Livesley, 2008). Also, the rates of borderline personality disorder among relatives of people with this disorder have been found to be as high as 24.9% (White, Gunderson, Zanarani, & Hudson, 2003). Individuals with borderline personality disorder report experiencing childhood physical, sexual, and/or emotional abuse at rates far greater than those observed in the general population (Afifi et al., 2010), indicating that environmental factors are also crucial. These findings would suggest that borderline personality disorder may be determined by an interaction between genetic factors and adverse environmental experiences. Consistent with this hypothesis, one study found that the highest rates of borderline personality disorder were among individuals with a borderline temperament (characterized by high novelty seeking and high harm-avoidance) and those who experienced childhood abuse and/or neglect (Joyce et al., 2003). Antisocial Personality Disorder Most human beings live in accordance with a moral compass, a sense of right and wrong. Most individuals learn at a very young age that there are certain things that should not be done. We learn that we should not lie or cheat. We are taught that it is wrong to take things that do not belong to us, and that it is wrong to exploit others for personal gain. We also learn the importance of living up to our responsibilities, of doing what we say we will do. People with antisocial personality disorder, however, do not seem to have a moral compass. These individuals act as though they neither have a sense of nor care about right or wrong. Not surprisingly, these people represent a serious problem for others and for society in general. According to the DSM-5, the individual with antisocial personality disorder (sometimes referred to as psychopathy) shows no regard at all for other people’s rights or feelings. This lack of regard is exhibited a number of ways and can include repeatedly performing illegal acts, lying to or conning others, impulsivity and recklessness, irritability and aggressiveness toward others, and failure to act in a responsible way (e.g., leaving debts unpaid) (APA, 2013). The worst part about antisocial personality disorder, however, is that people with this disorder have no remorse over one’s misdeeds; these people will hurt, manipulate, exploit, and abuse others and not feel any guilt. Signs of this disorder can emerge early in life; however, a person must be at least 18 years old to be diagnosed with antisocial personality disorder. People with antisocial personality disorder seem to view the world as self-serving and unkind. They seem to think that they should use whatever means necessary to get by in life. They tend to view others not as living, thinking, feeling beings, but rather as pawns to be used or abused for a specific purpose. They often have an over-inflated sense of themselves and can appear extremely arrogant. They frequently display superficial charm; for example, without really meaning it they might say exactly what they think another person wants to hear. They lack empathy: they are incapable of understanding the emotional point-of-view of others. People with this disorder may become involved in illegal enterprises, show cruelty toward others, leave their jobs with no plans to obtain another job, have multiple sexual partners, repeatedly get into fights with others, and show reckless disregard for themselves and others (e.g., repeated arrests for driving while intoxicated) (APA, 2013). A useful way to conceptualize antisocial personality disorder is boiling the diagnosis down to three major concepts: disinhibition, boldness, and meanness (Patrick, Fowles, & Krueger, 2009). Disinhibition is a propensity toward impulse control problems, lack of planning and forethought, insistence on immediate gratification, and inability to restrain behavior. Boldness describes a tendency to remain calm in threatening situations, high self-assurance, a sense of dominance, and a tendency toward thrill-seeking. Meanness is defined as “aggressive resource seeking without regard for others,” and is signaled by a lack of empathy, disdain for and lack of close relationships with others, and a tendency to accomplish goals through cruelty (Patrick et al., 2009, p. 913). Risk Factors for Antisocial Personality Disorder Antisocial personality disorder is observed in about 3.6% of the population; the disorder is much more common among males, with a 3 to 1 ratio of men to women, and it is more likely to occur in men who are younger, widowed, separated, divorced, of lower socioeconomic status, who live in urban areas, and who live in the western United States (Compton, Conway, Stinson, Colliver, & Grant, 2005). Compared to men with antisocial personality disorder, women with the disorder are more likely to have experienced emotional neglect and sexual abuse during childhood, and they are more likely to have had parents who abused substances and who engaged in antisocial behaviors themselves (Alegria et al., 2013). Table 15.3 shows some of the differences in the specific types of antisocial behaviors that men and women with antisocial personality disorder exhibit (Alegria et al., 2013). Men with antisocial personality disorder are more likely than women with antisocial personality disorder to Women with antisocial personality disorder are more likely than men with antisocial personality to do things that could easily hurt themselves or others receive three or more traffic tickets for reckless driving have their driver’s license suspended destroy others’ property start a fire on purpose make money illegally do anything that could lead to arrest hit someone hard enough to injure them hurt an animal on purpose run away from home overnight frequently miss school or work lie frequently forge someone’s signature get into a fight that comes to blows with an intimate partner live with others besides the family for at least one month harass, threaten, or blackmail someone Table 15.3 Gender Differences in Antisocial Personality Disorder Family, twin, and adoption studies suggest that both genetic and environmental factors influence the development of antisocial personality disorder, as well as general antisocial behavior (criminality, violence, aggressiveness) (Baker, Bezdjian, & Raine, 2006). Personality and temperament dimensions that are related to this disorder, including fearlessness, impulsive antisociality, and callousness, have a substantial genetic influence (Livesley & Jang, 2008). Adoption studies clearly demonstrate that the development of antisocial behavior is determined by the interaction of genetic factors and adverse environmental circumstances (Rhee & Waldman, 2002). For example, one investigation found that adoptees of biological parents with antisocial personality disorder were more likely to exhibit adolescent and adult antisocial behaviors if they were raised in adverse adoptive family environments (e.g., adoptive parents had marital problems, were divorced, used drugs, and had legal problems) than if they were raised in a more normal adoptive environment (Cadoret, Yates, Ed, Woodworth, & Stewart, 1995). Researchers who are interested in the importance of environment in the development of antisocial personality disorder have directed their attention to such factors as the community, the structure and functioning of the family, and peer groups. Each of these factors influences the likelihood of antisocial behavior. One longitudinal investigation of more than 800 Seattle-area youth measured risk factors for violence at 10, 14, 16, and 18 years of age (Herrenkohl et al., 2000). The risk factors examined included those involving the family, peers, and community. A portion of the findings from this study are provided in Figure 15.19 . Those with antisocial tendencies do not seem to experience emotions the way most other people do. These individuals fail to show fear in response to environment cues that signal punishment, pain, or noxious stimulation. For instance, they show less skin conductance (sweatiness on hands) in anticipation of electric shock than do people without antisocial tendencies (Hare, 1965). Skin conductance is controlled by the sympathetic nervous system and is used to assess autonomic nervous system functioning. When the sympathetic nervous system is active, people become aroused and anxious, and sweat gland activity increases. Thus, increased sweat gland activity, as assessed through skin conductance, is taken as a sign of arousal or anxiety. For those with antisocial personality disorder, a lack of skin conductance may indicate the presence of characteristics such as emotional deficits and impulsivity that underlie the propensity for antisocial behavior and negative social relationships (Fung et al., 2005). While emotional deficits may contribute to antisocial personality disorder, so too might an inability to relate to others’ pain. In a recent study, 80 prisoners were shown photos of people being intentionally hurt by others (e.g., someone crushing a person’s hand in an automobile door) while undergoing brain imaging (Decety, Skelly, & Kiehl, 2013). Prisoners who scored high on a test of antisocial tendencies showed significantly less activation in brain regions involved in the experience of empathy and feeling concerned for others than did prisoners with low scores on the antisocial test. Notably, the prisoners who scored high on the antisocial test showed greater activation in a brain area involved self-awareness, cognitive function, and interpersonal experience. The investigators suggested that the heightened activation in this region when watching social interactions involving one person harming another may reflect a propensity or desire for this kind of behavior. 15.11 Disorders in Childhood Learning Objectives By the end of this section, you will be able to: Describe the nature and symptoms of attention deficit/hyperactivity disorder and autism spectrum disorder Discuss the prevalence and factors that contribute to the development of these disorders Most of the disorders we have discussed so far are typically diagnosed in adulthood, although they can and sometimes do occur during childhood. However, there are a group of conditions that, when present, are diagnosed early in childhood, often before the time a child enters school. These conditions are listed in the DSM-5 as neurodevelopmental disorders , and they involve developmental problems in personal, social, academic, and intellectual functioning (APA, 2013). In this section, we will discuss two such disorders: attention deficit/ hyperactivity disorder and autism. Attention Deficit/Hyperactivity Disorder Diego is always active, from the time he wakes up in the morning until the time he goes to bed at night. His mother reports that he came out the womb kicking and screaming, and he has not stopped moving since. He has a sweet disposition, but always seems to be in trouble with his teachers, parents, and after-school program counselors. He seems to accidently break things; he lost his jacket three times last winter, and he never seems to sit still. His teachers believe he is a smart child, but he never finishes anything he starts and is so impulsive that he does not seem to learn much in school. Diego likely has attention deficit/hyperactivity disorder (ADHD) . The symptoms of this disorder were first described by Hans Hoffman in the 1920s. While taking care of his son while his wife was in the hospital giving birth to a second child, Hoffman noticed that the boy had trouble concentrating on his homework, had a short attention span, and had to repeatedly go over easy homework to learn the material (Jellinek & Herzog, 1999). Later, it was discovered that many hyperactive children—those who are fidgety, restless, socially disruptive, and have trouble with impulse control—also display short attention spans, problems with concentration, and distractibility. By the 1970s, it had become clear that many children who display attention problems often also exhibit signs of hyperactivity. In recognition of such findings, the DSM-III (published in 1980) included a new disorder: attention deficit disorder with and without hyperactivity, now known as attention deficit/hyperactivity disorder (ADHD). A child with ADHD shows a constant pattern of inattention and/or hyperactive and impulsive behavior that interferes with normal functioning (APA, 2013). Some of the signs of inattention include great difficulty with and avoidance of tasks that require sustained attention (such as conversations or reading), failure to follow instructions (often resulting in failure to complete school work and other duties), disorganization (difficulty keeping things in order, poor time management, sloppy and messy work), lack of attention to detail, becoming easily distracted, and forgetfulness. Hyperactivity is characterized by excessive movement, and includes fidgeting or squirming, leaving one’s seat in situations when remaining seated is expected, having trouble sitting still (e.g., in a restaurant), running about and climbing on things, blurting out responses before another person’s question or statement has been completed, difficulty waiting one’s turn for something, and interrupting and intruding on others. Frequently, the hyperactive child comes across as noisy and boisterous. The child’s behavior is hasty, impulsive, and seems to occur without much forethought; these characteristics may explain why adolescents and young adults diagnosed with ADHD receive more traffic tickets and have more automobile accidents than do others (Thompson, Molina, Pelham, & Gnagy, 2007). ADHD occurs in about 5% of children (APA, 2013). On the average, boys are 3 times more likely to have ADHD than are girls; however, such findings might reflect the greater propensity of boys to engage in aggressive and antisocial behavior and thus incur a greater likelihood of being referred to psychological clinics (Barkley, 2006). Children with ADHD face severe academic and social challenges. Compared to their non-ADHD counterparts, children with ADHD have lower grades and standardized test scores and higher rates of expulsion, grade retention, and dropping out (Loe & Feldman, 2007). they also are less well-liked and more often rejected by their peers (Hoza et al., 2005). Previously, ADHD was thought to fade away by adolescence. However, longitudinal studies have suggested that ADHD is a chronic problem, one that can persist into adolescence and adulthood (Barkley, Fischer, Smallish, & Fletcher, 2002). A recent study found that 29.3% of adults who had been diagnosed with ADHD decades earlier still showed symptoms (Barbaresi et al., 2013). Somewhat troubling, this study also reported that nearly 81% of those whose ADHD persisted into adulthood had experienced at least one other comorbid disorder, compared to 47% of those whose ADHD did not persist. Life Problems from ADHD Children diagnosed with ADHD face considerably worse long-term outcomes than do those children who do not receive such a diagnosis. In one investigation, 135 adults who had been identified as having ADHD symptoms in the 1970s were contacted decades later and interviewed (Klein et al., 2012). Compared to a control sample of 136 participants who had never been diagnosed with ADHD, those who were diagnosed as children: had worse educational attainment (more likely to have dropped out of high school and less likely to have earned a bachelor’s degree); had lower socioeconomic status; held less prestigious occupational positions; were more likely to be unemployed; made considerably less in salary; scored worse on a measure of occupational functioning (indicating, for example, lower job satisfaction, poorer work relationships, and more firings); scored worse on a measure of social functioning (indicating, for example, fewer friendships and less involvement in social activities); were more likely to be divorced; and were more likely to have non-alcohol-related substance abuse problems. (Klein et al., 2012) Longitudinal studies also show that children diagnosed with ADHD are at higher risk for substance abuse problems. One study reported that childhood ADHD predicted later drinking problems, daily smoking, and use of marijuana and other illicit drugs (Molina & Pelham, 2003). The risk of substance abuse problems appears to be even greater for those with ADHD who also exhibit antisocial tendencies (Marshal & Molina, 2006). Causes of ADHD Family and twin studies indicate that genetics play a significant role in the development of ADHD. Burt (2009), in a review of 26 studies, reported that the median rate of concordance for identical twins was .66 (one study reported a rate of .90), whereas the median concordance rate for fraternal twins was .20. This study also found that the median concordance rate for unrelated (adoptive) siblings was .09; although this number is small, it is greater than 0, thus suggesting that the environment may have at least some influence. Another review of studies concluded that the heritability of inattention and hyperactivity were 71% and 73%, respectively (Nikolas & Burt, 2010). The specific genes involved in ADHD are thought to include at least two that are important in the regulation of the neurotransmitter dopamine (Gizer, Ficks, & Waldman, 2009), suggesting that dopamine may be important in ADHD. Indeed, medications used in the treatment of ADHD, such as methylphenidate (Ritalin) and amphetamine with dextroamphetamine (Adderall), have stimulant qualities and elevate dopamine activity. People with ADHD show less dopamine activity in key regions of the brain, especially those associated with motivation and reward (Volkow et al., 2009), which provides support to the theory that dopamine deficits may be a vital factor in the development this disorder (Swanson et al., 2007). Brain imaging studies have shown that children with ADHD exhibit abnormalities in their frontal lobes, an area in which dopamine is in abundance. Compared to children without ADHD, those with ADHD appear to have smaller frontal lobe volume, and they show less frontal lobe activation when performing mental tasks. Recall that one of the functions of the frontal lobes is to inhibit our behavior. Thus, abnormalities in this region may go a long way toward explaining the hyperactive, uncontrolled behavior of ADHD. By the 1970s, many had become aware of the connection between nutritional factors and childhood behavior. At the time, much of the public believed that hyperactivity was caused by sugar and food additives, such as artificial coloring and flavoring. Undoubtedly, part of the appeal of this hypothesis was that it provided a simple explanation of (and treatment for) behavioral problems in children. A statistical review of 16 studies, however, concluded that sugar consumption has no effect at all on the behavioral and cognitive performance of children (Wolraich, Wilson, & White, 1995). Additionally, although food additives have been shown to increase hyperactivity in non-ADHD children, the effect is rather small (McCann et al., 2007). Numerous studies, however, have shown a significant relationship between exposure to nicotine in cigarette smoke during the prenatal period and ADHD (Linnet et al., 2003). Maternal smoking during pregnancy is associated with the development of more severe symptoms of the disorder (Thakur et al., 2013). Is ADHD caused by poor parenting? Not likely. Remember, the genetics studies discussed above suggested that the family environment does not seem to play much of a role in the development of this disorder; if it did, we would expect the concordance rates to be higher for fraternal twins and adoptive siblings than has been demonstrated. All things considered, the evidence seems to point to the conclusion that ADHD is triggered more by genetic and neurological factors and less by social or environmental ones. Autism Spectrum Disorder A seminal paper published in 1943 by psychiatrist Leo Kanner described an unusual neurodevelopmental condition he observed in a group of children. He called this condition early infantile autism, and it was characterized mainly by an inability to form close emotional ties with others, speech and language abnormalities, repetitive behaviors, and an intolerance of minor changes in the environment and in normal routines (Bregman, 2005). What the DSM-5 refers to as autism spectrum disorder today, is a direct extension of Kanner’s work. Autism spectrum disorder is probably the most misunderstood and puzzling of the neurodevelopmental disorders. Children with this disorder show signs of significant disturbances in three main areas: (a) deficits in social interaction, (b) deficits in communication, and (c) repetitive patterns of behavior or interests. These disturbances appear early in life and cause serious impairments in functioning (APA, 2013). The child with autism spectrum disorder might exhibit deficits in social interaction by not initiating conversations with other children or turning their head away when spoken to. These children do not make eye contact with others and seem to prefer playing alone rather than with others. In a certain sense, it is almost as though these individuals live in a personal and isolated social world others are simply not privy to or able to penetrate. Communication deficits can range from a complete lack of speech, to one word responses (e.g., saying “Yes” or “No” when replying to questions or statements that require additional elaboration), to echoed speech (e.g., parroting what another person says, either immediately or several hours or even days later), to difficulty maintaining a conversation because of an inability to reciprocate others’ comments. These deficits can also include problems in using and understanding nonverbal cues (e.g., facial expressions, gestures, and postures) that facilitate normal communication. Repetitive patterns of behavior or interests can be exhibited a number of ways. The child might engage in stereotyped, repetitive movements (rocking, head-banging, or repeatedly dropping an object and then picking it up), or she might show great distress at small changes in routine or the environment. For example, the child might throw a temper tantrum if an object is not in its proper place or if a regularly-scheduled activity is rescheduled. In some cases, the person with autism spectrum disorder might show highly restricted and fixated interests that appear to be abnormal in their intensity. For instance, the person might learn and memorize every detail about something even though doing so serves no apparent purpose. Importantly, autism spectrum disorder is not the same thing as intellectual disability, although these two conditions are often comorbid. The DSM-5 specifies that the symptoms of autism spectrum disorder are not caused or explained by intellectual disability. Life Problems From Autism Spectrum Disorder Autism spectrum disorder is referred to in everyday language as autism; in fact, the disorder was termed “autistic disorder” in earlier editions of the DSM, and its diagnostic criteria were much narrower than those of autism spectrum disorder. The qualifier “spectrum” in autism spectrum disorder is used to indicate that individuals with the disorder can show a range, or spectrum, of symptoms that vary in their magnitude and severity: some severe, others less severe. The previous edition of the DSM included a diagnosis of Asperger’s disorder, generally recognized as a less severe form of autistic disorder; individuals diagnosed with Asperger’s disorder were described as having average or high intelligence and a strong vocabulary, but exhibiting impairments in social interaction and social communication, such as talking only about their special interests (Wing, Gould, & Gillberg, 2011). However, because research has failed to demonstrate that Asperger’s disorder differs qualitatively from autistic disorder, the DSM-5 does not include it, which is prompting concerns among some parents that their children may no longer be eligible for special services (“Asperger’s Syndrome Dropped,” 2012). Some individuals with autism spectrum disorder, particularly those with better language and intellectual skills, can live and work independently as adults. However, most do not because the symptoms remain sufficient to cause serious impairment in many realms of life (APA, 2013). Link to Learning Here is an instructive and poignant video highlighting severe autism. Currently, estimates indicate that nearly 1 in 88 children in the United States has autism spectrum disorder; the disorder is 5 times more common in boys (1 out of 54) than girls (1 out of 252) (CDC, 2012). Rates of autistic spectrum disorder have increased dramatically since the 1980s. For example, California saw an increase of 273% in reported cases from 1987 through 1998 (Byrd, 2002); between 2000 and 2008, the rate of autism diagnoses in the United States increased 78% (CDC, 2012). Although it is difficult to interpret this increase, it is possible that the rise in prevalence is the result of the broadening of the diagnosis, increased efforts to identify cases in the community, and greater awareness and acceptance of the diagnosis. In addition, mental health professionals are now more knowledgeable about autism spectrum disorder and are better equipped to make the diagnosis, even in subtle cases (Novella, 2008). Dig Deeper Why Is the Prevalence Rate of ADHD Increasing? Many people believe that the rates of ADHD have increased in recent years, and there is evidence to support this contention. In a recent study, investigators found that the parent-reported prevalence of ADHD among children (4–17 years old) in the United States increased by 22% during a 4-year period, from 7.8% in 2003 to 9.5% in 2007 (CDC, 2010). Over time this increase in parent-reported ADHD was observed in all sociodemographic groups and was reflected by substantial increases in 12 states (Indiana, North Carolina, and Colorado were the top three). The increases were greatest for older teens (ages 15–17), multiracial and Hispanic children, and children with a primary language other than English. Another investigation found that from 1998–2000 through 2007–2009 the parent-reported prevalence of ADHD increased among U.S. children between the ages of 5–17 years old, from 6.9% to 9.0% (Akinbami, Liu, Pastor, & Reuben, 2011). A major weakness of both studies was that children were not actually given a formal diagnosis. Instead, parents were simply asked whether or not a doctor or other health-care provider had ever told them their child had ADHD; the reported prevalence rates thus may have been affected by the accuracy of parental memory. Nevertheless, the findings from these studies raise important questions concerning what appears to be a demonstrable rise in the prevalence of ADHD. Although the reasons underlying this apparent increase in the rates of ADHD over time are poorly understood and, at best, speculative, several explanations are viable: ADHD may be over-diagnosed by doctors who are too quick to medicate children as a behavior treatment. There is greater awareness of ADHD now than in the past. Nearly everyone has heard of ADHD, and most parents and teachers are aware of its key symptoms. Thus, parents may be quick to take their children to a doctor if they believe their child possesses these symptoms, or teachers may be more likely now than in the past to notice the symptoms and refer the child for evaluation. The use of computers, video games, iPhones, and other electronic devices has become pervasive among children in the early 21st century, and these devices could potentially shorten children’s attentions spans. Thus, what might seem like inattention to some parents and teachers could simply reflect exposure to too much technology. ADHD diagnostic criteria have changed over time. Causes of Autism Spectrum Disorder Early theories of autism placed the blame squarely on the shoulders of the child’s parents, particularly the mother. Bruno Bettelheim (an Austrian-born American child psychologist who was heavily influenced by Sigmund Freud’s ideas) suggested that a mother’s ambivalent attitudes and her frozen and rigid emotions toward her child were the main causal factors in childhood autism. In what must certainly stand as one of the more controversial assertions in psychology over the last 50 years, he wrote, “I state my belief that the precipitating factor in infantile autism is the parent’s wish that his child should not exist” (Bettelheim, 1967, p. 125). As you might imagine, Bettelheim did not endear himself to a lot of people with this position; incidentally, no scientific evidence exists supporting his claims. The exact causes of autism spectrum disorder remain unknown despite massive research efforts over the last two decades (Meek, Lemery-Chalfant, Jahromi, & Valiente, 2013). Autism appears to be strongly influenced by genetics, as identical twins show concordance rates of 60%–90%, whereas concordance rates for fraternal twins and siblings are 5%–10% (Autism Genome Project Consortium, 2007). Many different genes and gene mutations have been implicated in autism (Meek et al., 2013). Among the genes involved are those important in the formation of synaptic circuits that facilitate communication between different areas of the brain (Gauthier et al., 2011). A number of environmental factors are also thought to be associated with increased risk for autism spectrum disorder, at least in part, because they contribute to new mutations. These factors include exposure to pollutants, such as plant emissions and mercury, urban versus rural residence, and vitamin D deficiency (Kinney, Barch, Chayka, Napoleon, & Munir, 2009). Child Vaccinations and Autism Spectrum Disorder In the late 1990s, a prestigious medical journal published an article purportedly showing that autism is triggered by the MMR (measles, mumps, and rubella) vaccine. These findings were very controversial and drew a great deal of attention, sparking an international forum on whether children should be vaccinated. In a shocking turn of events, some years later the article was retracted by the journal that had published it after accusations of fraud on the part of the lead researcher. Despite the retraction, the reporting in popular media led to concerns about a possible link between vaccines and autism persisting. A recent survey of parents, for example, found that roughly a third of respondents expressed such a concern (Kennedy, LaVail, Nowak, Basket, & Landry, 2011); and perhaps fearing that their children would develop autism, more than 10% of parents of young children refuse or delay vaccinations (Dempsey et al., 2011). Some parents of children with autism mounted a campaign against scientists who refuted the vaccine-autism link. Even politicians and several well-known celebrities weighed in; for example, actress Jenny McCarthy (who believed that a vaccination caused her son’s autism) co-authored a book on the matter. However, there is no scientific evidence that a link exists between autism and vaccinations (Hughes, 2007). Indeed, a recent study compared the vaccination histories of 256 children with autism spectrum disorder with that of 752 control children across three time periods during their first two years of life (birth to 3 months, birth to 7 months, and birth to 2 years) (DeStefano, Price, & Weintraub, 2013). At the time of the study, the children were between 6 and 13 years old, and their prior vaccination records were obtained. Because vaccines contain immunogens (substances that fight infections), the investigators examined medical records to see how many immunogens children received to determine if those children who received more immunogens were at greater risk for developing autism spectrum disorder. The results of this study, a portion of which are shown in Figure 15.20 , clearly demonstrate that the quantity of immunogens from vaccines received during the first two years of life were not at all related to the development of autism spectrum disorder. There is not a relationship between vaccinations and autism spectrum disorders. Why does concern over vaccines and autism spectrum disorder persist? Since the proliferation of the Internet in the 1990s, parents have been constantly bombarded with online information that can become magnified and take on a life of its own. The enormous volume of electronic information pertaining to autism spectrum disorder, combined with how difficult it can be to grasp complex scientific concepts, can make separating good research from bad challenging (Downs, 2008). Notably, the study that fueled the controversy reported that 8 out of 12 children—according to their parents—developed symptoms consistent with autism spectrum disorder shortly after receiving a vaccination. To conclude that vaccines cause autism spectrum disorder on this basis, as many did, is clearly incorrect for a number of reasons, not the least of which is because correlation does not imply causation, as you’ve learned. Additionally, as was the case with diet and ADHD in the 1970s, the notion that autism spectrum disorder is caused by vaccinations is appealing to some because it provides a simple explanation for this condition. Like all disorders, however, there are no simple explanations for autism spectrum disorder. Although the research discussed above has shed some light on its causes, science is still a long way from complete understanding of the disorder. 15.2 Diagnosing and Classifying Psychological Disorders Learning Objectives By the end of this section, you will be able to: Explain why classification systems are necessary in the study of psychopathology Describe the basic features of the Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition (DSM-5) Discuss changes in the DSM over time, including criticisms of the current edition Identify which disorders are generally the most common A first step in the study of psychological disorders is carefully and systematically discerning significant signs and symptoms. How do mental health professionals ascertain whether or not a person’s inner states and behaviors truly represent a psychological disorder? Arriving at a proper diagnosis —that is, appropriately identifying and labeling a set of defined symptoms—is absolutely crucial. This process enables professionals to use a common language with others in the field and aids in communication about the disorder with the patient, colleagues and the public. A proper diagnosis is an essential element to guide proper and successful treatment. For these reasons, classification systems that organize psychological disorders systematically are necessary. The Diagnostic and Statistical Manual of Mental Disorders (DSM) Although a number of classification systems have been developed over time, the one that is used by most mental health professionals in the United States is the Diagnostic and Statistical Manual of Mental Disorders (DSM-5) , published by the American Psychiatric Association (2013). (Note that the American Psychiatric Association differs from the American Psychological Association; both are abbreviated APA.) The first edition of the DSM, published in 1952, classified psychological disorders according to a format developed by the U.S. Army during World War II (Clegg, 2012). In the years since, the DSM has undergone numerous revisions and editions. The most recent edition, published in 2013, is the DSM-5 (APA, 2013). The DSM-5 includes many categories of disorders (e.g., anxiety disorders, depressive disorders, and dissociative disorders). Each disorder is described in detail, including an overview of the disorder (diagnostic features), specific symptoms required for diagnosis (diagnostic criteria), prevalence information (what percent of the population is thought to be afflicted with the disorder), and risk factors associated with the disorder. Figure 15.4 shows lifetime prevalence rates—the percentage of people in a population who develop a disorder in their lifetime—of various psychological disorders among U.S. adults. These data were based on a national sample of 9,282 U.S. residents (National Comorbidity Survey, 2007). The DSM-5 also provides information about comorbidity ; the co-occurrence of two disorders. For example, the DSM-5 mentions that 41% of people with obsessive-compulsive disorder (OCD) also meet the diagnostic criteria for major depressive disorder ( Figure 15.5 ). Drug use is highly comorbid with other mental illnesses; 6 out of 10 people who have a substance use disorder also suffer from another form of mental illness (National Institute on Drug Abuse [NIDA], 2007). The DSM has changed considerably in the half-century since it was originally published. The first two editions of the DSM, for example, listed homosexuality as a disorder; however, in 1973, the APA voted to remove it from the manual (Silverstein, 2009). Additionally, beginning with the DSM-III in 1980, mental disorders have been described in much greater detail, and the number of diagnosable conditions has grown steadily, as has the size of the manual itself. DSM-I included 106 diagnoses and was 130 total pages, whereas DSM-III included more than 2 times as many diagnoses (265) and was nearly seven times its size (886 total pages) (Mayes & Horowitz, 2005). Although DSM-5 is longer than DSM-IV, the volume includes only 237 disorders, a decrease from the 297 disorders that were listed in DSM-IV. The latest edition, DSM-5, includes revisions in the organization and naming of categories and in the diagnostic criteria for various disorders (Regier, Kuhl, & Kupfer, 2012), while emphasizing careful consideration of the importance of gender and cultural difference in the expression of various symptoms (Fisher, 2010). Some believe that establishing new diagnoses might overpathologize the human condition by turning common human problems into mental illnesses (The Associated Press, 2013). Indeed, the finding that nearly half of all Americans will meet the criteria for a DSM disorder at some point in their life (Kessler et al., 2005) likely fuels much of this skepticism. The DSM-5 is also criticized on the grounds that its diagnostic criteria have been loosened, thereby threatening to “turn our current diagnostic inflation into diagnostic hyperinflation” (Frances, 2012, para. 22). For example, DSM-IV specified that the symptoms of major depressive disorder must not be attributable to normal bereavement (loss of a loved one). The DSM-5, however, has removed this bereavement exclusion, essentially meaning that grief and sadness after a loved one’s death can constitute major depressive disorder. The International Classification of Diseases A second classification system, the International Classification of Diseases (ICD) , is also widely recognized. Published by the World Health Organization (WHO), the ICD was developed in Europe shortly after World War II and, like the DSM, has been revised several times. The categories of psychological disorders in both the DSM and ICD are similar, as are the criteria for specific disorders; however, some differences exist. Although the ICD is used for clinical purposes, this tool is also used to examine the general health of populations and to monitor the prevalence of diseases and other health problems internationally (WHO, 2013). The ICD is in its 10th edition (ICD-10); however, efforts are now underway to develop a new edition (ICD-11) that, in conjunction with the changes in DSM-5, will help harmonize the two classification systems as much as possible (APA, 2013). A study that compared the use of the two classification systems found that worldwide the ICD is more frequently used for clinical diagnosis, whereas the DSM is more valued for research (Mezzich, 2002). Most research findings concerning the etiology and treatment of psychological disorders are based on criteria set forth in the DSM (Oltmanns & Castonguay, 2013). The DSM also includes more explicit disorder criteria, along with an extensive and helpful explanatory text (Regier et al., 2012). The DSM is the classification system of choice among U.S. mental health professionals, and this chapter is based on the DSM paradigm. The Compassionate View of Psychological Disorders As these disorders are outlined, please bear two things in mind. First, remember that psychological disorders represent extremes of inner experience and behavior. If, while reading about these disorders, you feel that these descriptions begin to personally characterize you, do not worry—this moment of enlightenment probably means nothing more than you are normal. Each of us experiences episodes of sadness, anxiety, and preoccupation with certain thoughts—times when we do not quite feel ourselves. These episodes should not be considered problematic unless the accompanying thoughts and behaviors become extreme and have a disruptive effect on one’s life. Second, understand that people with psychological disorders are far more than just embodiments of their disorders. We do not use terms such as schizophrenics, depressives, or phobics because they are labels that objectify people who suffer from these conditions, thus promoting biased and disparaging assumptions about them. It is important to remember that a psychological disorder is not what a person is ; it is something that a person has —through no fault of his or her own. As is the case with cancer or diabetes, those with psychological disorders suffer debilitating, often painful conditions that are not of their own choosing. These individuals deserve to be viewed and treated with compassion, understanding, and dignity. 15.3 Perspectives on Psychological Disorders Learning Objectives By the end of this section, you will be able to: Discuss supernatural perspectives on the origin of psychological disorders, in their historical context Describe modern biological and psychological perspectives on the origin of psychological disorders Identify which disorders generally show the highest degree of heritability Describe the diathesis-stress model and its importance to the study of psychopathology Scientists and mental health professionals may adopt different perspectives in attempting to understand or explain the underlying mechanisms that contribute to the development of a psychological disorder. The perspective used in explaining a psychological disorder is extremely important, in that it will consist of explicit assumptions regarding how best to study the disorder, its etiology, and what kinds of therapies or treatments are most beneficial. Different perspectives provide alternate ways for how to think about the nature of psychopathology. Supernatural Perspectives of Psychological Disorders For centuries, psychological disorders were viewed from a supernatural perspective: attributed to a force beyond scientific understanding. Those afflicted were thought to be practitioners of black magic or possessed by spirits ( Figure 15.6 ) (Maher & Maher, 1985). For example, convents throughout Europe in the 16th and 17th centuries reported hundreds of nuns falling into a state of frenzy in which the afflicted foamed at the mouth, screamed and convulsed, sexually propositioned priests, and confessed to having carnal relations with devils or Christ. Although, today, these cases would suggest serious mental illness; at the time, these events were routinely explained as possession by devilish forces (Waller, 2009a). Similarly, grievous fits by young girls are believed to have precipitated the witch panic in New England late in the 17th century (Demos, 1983). Such beliefs in supernatural causes of mental illness are still held in some societies today; for example, beliefs that supernatural forces cause mental illness are common in some cultures in modern-day Nigeria (Aghukwa, 2012). Dig Deeper Dancing Mania Between the 11th and 17th centuries, a curious epidemic swept across Western Europe. Groups of people would suddenly begin to dance with wild abandon. This compulsion to dance—referred to as dancing mania —sometimes gripped thousands of people at a time ( Figure 15.7 ). Historical accounts indicate that those afflicted would sometimes dance with bruised and bloody feet for days or weeks, screaming of terrible visions and begging priests and monks to save their souls (Waller, 2009b). What caused dancing mania is not known, but several explanations have been proposed, including spider venom and ergot poisoning (“Dancing Mania,” 2011). Historian John Waller (2009a, 2009b) has provided a comprehensive and convincing explanation of dancing mania that suggests the phenomenon was attributable to a combination of three factors: psychological distress, social contagion, and belief in supernatural forces. Waller argued that various disasters of the time (such as famine, plagues, and floods) produced high levels of psychological distress that could increase the likelihood of succumbing to an involuntary trance state. Waller indicated that anthropological studies and accounts of possession rituals show that people are more likely to enter a trance state if they expect it to happen, and that entranced individuals behave in a ritualistic manner, their thoughts and behavior shaped by the spiritual beliefs of their culture. Thus, during periods of extreme physical and mental distress, all it took were a few people—believing themselves to have been afflicted with a dancing curse—to slip into a spontaneous trance and then act out the part of one who is cursed by dancing for days on end. Biological Perspectives of Psychological Disorders The biological perspective views psychological disorders as linked to biological phenomena, such as genetic factors, chemical imbalances, and brain abnormalities; it has gained considerable attention and acceptance in recent decades (Wyatt & Midkiff, 2006). Evidence from many sources indicates that most psychological disorders have a genetic component; in fact, there is little dispute that some disorders are largely due to genetic factors. The graph in Figure 15.8 shows heritability estimates for schizophrenia. Findings such as these have led many of today’s researchers to search for specific genes and genetic mutations that contribute to mental disorders. Also, sophisticated neural imaging technology in recent decades has revealed how abnormalities in brain structure and function might be directly involved in many disorders, and advances in our understanding of neurotransmitters and hormones have yielded insights into their possible connections. The biological perspective is currently thriving in the study of psychological disorders. The Diathesis-Stress Model of Psychological Disorders Despite advances in understanding the biological basis of psychological disorders, the psychosocial perspective is still very important. This perspective emphasizes the importance of learning, stress, faulty and self-defeating thinking patterns, and environmental factors. Perhaps the best way to think about psychological disorders, then, is to view them as originating from a combination of biological and psychological processes. Many develop not from a single cause, but from a delicate fusion between partly biological and partly psychosocial factors. The diathesis-stress model (Zuckerman, 1999) integrates biological and psychosocial factors to predict the likelihood of a disorder. This diathesis-stress model suggests that people with an underlying predisposition for a disorder (i.e., a diathesis) are more likely than others to develop a disorder when faced with adverse environmental or psychological events (i.e., stress), such as childhood maltreatment, negative life events, trauma, and so on. A diathesis is not always a biological vulnerability to an illness; some diatheses may be psychological (e.g., a tendency to think about life events in a pessimistic, self-defeating way). The key assumption of the diathesis-stress model is that both factors, diathesis and stress, are necessary in the development of a disorder. Different models explore the relationship between the two factors: the level of stress needed to produce the disorder is inversely proportional to the level of diathesis. 15.4 Anxiety Disorders Learning Objectives By the end of this section, you will be able to: Distinguish normal anxiety from pathological anxiety List and describe the major anxiety disorders, including their main features and prevalence Describe basic psychological and biological factors that are suspected to be important in the etiology of anxiety disorder Everybody experiences anxiety from time to time. Although anxiety is closely related to fear, the two states possess important differences. Fear involves an instantaneous reaction to an imminent threat, whereas anxiety involves apprehension, avoidance, and cautiousness regarding a potential threat, danger, or other negative event (Craske, 1999). While anxiety is unpleasant to most people, it is important to our health, safety, and well-being. Anxiety motivates us to take actions—such as preparing for exams, watching our weight, showing up to work on time—that enable us to avert potential future problems. Anxiety also motivates us to avoid certain things—such as running up debts and engaging in illegal activities—that could lead to future trouble. Most individuals’ level and duration of anxiety approximates the magnitude of the potential threat they face. For example, suppose a single woman in her late 30s who wishes to marry is concerned about the possibility of having to settle for a spouse who is less attractive and educated than desired. This woman likely would experience anxiety of greater intensity and duration than would a 21-year-old college junior who is having trouble finding a date for the annual social. Some people, however, experience anxiety that is excessive, persistent, and greatly out of proportion to the actual threat; if one’s anxiety has a disruptive influence on one’s life, this is a strong indicator that the individual is experiencing an anxiety disorder. Anxiety disorders are characterized by excessive and persistent fear and anxiety, and by related disturbances in behavior (APA, 2013). Although anxiety is universally experienced, anxiety disorders cause considerable distress. As a group, anxiety disorders are common: approximately 25%–30% of the U.S. population meets the criteria for at least one anxiety disorder during their lifetime (Kessler et al., 2005). Also, these disorders appear to be much more common in women than they are in men; within a 12-month period, around 23% of women and 14% of men will experience at least one anxiety disorder (National Comorbidity Survey, 2007). Anxiety disorders are the most frequently occurring class of mental disorders and are often comorbid with each other and with other mental disorders (Kessler, Ruscio, Shear, & Wittchen, 2009). Specific Phobia Phobia is a Greek word that means fear. A person diagnosed with a specific phobia (formerly known as simple phobia ) experiences excessive, distressing, and persistent fear or anxiety about a specific object or situation (such as animals, enclosed spaces, elevators, or flying) (APA, 2013). Even though people realize their level of fear and anxiety in relation to the phobic stimulus is irrational, some people with a specific phobia may go to great lengths to avoid the phobic stimulus (the object or situation that triggers the fear and anxiety). Typically, the fear and anxiety a phobic stimulus elicits is disruptive to the person’s life. For example, a man with a phobia of flying might refuse to accept a job that requires frequent air travel, thus negatively affecting his career. Clinicians who have worked with people who have specific phobias have encountered many kinds of phobias, some of which are shown in Table 15.1 . Phobia Feared Object or Situation Acrophobia heights Aerophobia flying Arachnophobia spiders Claustrophobia enclosed spaces Cynophobia dogs Hematophobia blood Ophidiophobia snakes Taphophobia being buried alive Trypanophobia injections Xenophobia strangers Table 15.1 Specific Phobias Specific phobias are common; in the United States, around 12.5% of the population will meet the criteria for a specific phobia at some point in their lifetime (Kessler et al., 2005). One type of phobia, agoraphobia , is listed in the DSM-5 as a separate anxiety disorder. Agoraphobia, which literally means “fear of the marketplace,” is characterized by intense fear, anxiety, and avoidance of situations in which it might be difficult to escape or receive help if one experiences symptoms of a panic attack (a state of extreme anxiety that we will discuss shortly). These situations include public transportation, open spaces (parking lots), enclosed spaces (stores), crowds, or being outside the home alone (APA, 2013). About 1.4% of Americans experience agoraphobia during their lifetime (Kessler et al., 2005). Acquisition of Phobias Through Learning Many theories suggest that phobias develop through learning. Rachman (1977) proposed that phobias can be acquired through three major learning pathways. The first pathway is through classical conditioning . As you may recall, classical conditioning is a form of learning in which a previously neutral stimulus is paired with an unconditioned stimulus (UCS) that reflexively elicits an unconditioned response (UCR), eliciting the same response through its association with the unconditioned stimulus. The response is called a conditioned response (CR). For example, a child who has been bitten by a dog may come to fear dogs because of her past association with pain. In this case, the dog bite is the UCS and the fear it elicits is the UCR. Because a dog was associated with the bite, any dog may come to serve as a conditioned stimulus, thereby eliciting fear; the fear the child experiences around dogs, then, becomes a CR. The second pathway of phobia acquisition is through vicarious learning, such as modeling . For example, a child who observes his cousin react fearfully to spiders may later express the same fears, even though spiders have never presented any danger to him. This phenomenon has been observed in both humans and nonhuman primates (Olsson & Phelps, 2007). A study of laboratory-reared monkeys readily acquired a fear of snakes after observing wild-reared monkeys react fearfully to snakes (Mineka & Cook, 1993). The third pathway is through verbal transmission or information. For example, a child whose parents, siblings, friends, and classmates constantly tell her how disgusting and dangerous snakes are may come to acquire a fear of snakes. Interestingly, people are more likely to develop phobias of things that do not represent much actual danger to themselves, such as animals and heights, and are less likely to develop phobias toward things that present legitimate danger in contemporary society, such as motorcycles and weapons (Öhman & Mineka, 2001). Why might this be so? One theory suggests that the human brain is evolutionarily predisposed to more readily associate certain objects or situations with fear (Seligman, 1971). This theory argues that throughout our evolutionary history, our ancestors associated certain stimuli (e.g., snakes, spiders, heights, and thunder) with potential danger. As time progressed, the mind has become adapted to more readily develop fears of these things than of others. Experimental evidence has consistently demonstrated that conditioned fears develop more readily to fear-relevant stimuli (images of snakes and spiders) than to fear-irrelevant stimuli (images of flowers and berries) (Öhman & Mineka, 2001). Such prepared learning has also been shown to occur in monkeys. In one study (Cook & Mineka, 1989), monkeys watched videotapes of model monkeys reacting fearfully to either fear-relevant stimuli (toy snakes or a toy crocodile) or fear-irrelevant stimuli (flowers or a toy rabbit). The observer monkeys developed fears of the fear-relevant stimuli but not the fear-irrelevant stimuli. Social Anxiety Disorder Social anxiety disorder (formerly called social phobia) is characterized by extreme and persistent fear or anxiety and avoidance of social situations in which the person could potentially be evaluated negatively by others (APA, 2013). As with specific phobias, social anxiety disorder is common in the United States; a little over 12% of all Americans experience social anxiety disorder during their lifetime (Kessler et al., 2005). The heart of the fear and anxiety in social anxiety disorder is the person’s concern that he may act in a humiliating or embarrassing way, such as appearing foolish, showing symptoms of anxiety (blushing), or doing or saying something that might lead to rejection (such as offending others). The kinds of social situations in which individuals with social anxiety disorder usually have problems include public speaking, having a conversation, meeting strangers, eating in restaurants, and, in some cases, using public restrooms. Although many people become anxious in social situations like public speaking, the fear, anxiety, and avoidance experienced in social anxiety disorder are highly distressing and lead to serious impairments in life. Adults with this disorder are more likely to experience lower educational attainment and lower earnings (Katzelnick et al., 2001), perform more poorly at work and are more likely to be unemployed (Moitra, Beard, Weisberg, & Keller, 2011), and report greater dissatisfaction with their family lives, friends, leisure activities, and income (Stein & Kean, 2000). When people with social anxiety disorder are unable to avoid situations that provoke anxiety, they typically perform safety behaviors : mental or behavioral acts that reduce anxiety in social situations by reducing the chance of negative social outcomes. Safety behaviors include avoiding eye contact, rehearsing sentences before speaking, talking only briefly, and not talking about oneself (Alden & Bieling, 1998). Other examples of safety behaviors include the following (Marker, 2013): assuming roles in social situations that minimize interaction with others (e.g., taking pictures, setting up equipment, or helping prepare food) asking people many questions to keep the focus off of oneself selecting a position to avoid scrutiny or contact with others (sitting in the back of the room) wearing bland, neutral clothes to avoid drawing attention to oneself avoiding substances or activities that might cause anxiety symptoms (such as caffeine, warm clothing, and physical exercise) Although these behaviors are intended to prevent the person with social anxiety disorder from doing something awkward that might draw criticism, these actions usually exacerbate the problem because they do not allow the individual to disconfirm his negative beliefs, often eliciting rejection and other negative reactions from others (Alden & Bieling, 1998). People with social anxiety disorder may resort to self-medication, such as drinking alcohol, as a means to avert the anxiety symptoms they experience in social situations (Battista & Kocovski, 2010). The use of alcohol when faced with such situations may become negatively reinforcing: encouraging individuals with social anxiety disorder to turn to the substance whenever they experience anxiety symptoms. The tendency to use alcohol as a coping mechanism for social anxiety, however, can come with a hefty price tag: a number of large scale studies have reported a high rate of comorbidity between social anxiety disorder and alcohol use disorder (Morris, Stewart, & Ham, 2005). As with specific phobias, it is highly probable that the fears inherent to social anxiety disorder can develop through conditioning experiences. For example, a child who is subjected to early unpleasant social experiences (e.g., bullying at school) may develop negative social images of herself that become activated later in anxiety-provoking situations (Hackmann, Clark, & McManus, 2000). Indeed, one study reported that 92% of a sample of adults with social anxiety disorder reported a history of severe teasing in childhood, compared to only 35% of a sample of adults with panic disorder (McCabe, Antony, Summerfeldt, Liss, & Swinson, 2003). One of the most well-established risk factors for developing social anxiety disorder is behavioral inhibition (Clauss & Blackford, 2012). Behavioral inhibition is thought to be an inherited trait, and it is characterized by a consistent tendency to show fear and restraint when presented with unfamiliar people or situations (Kagan, Reznick, & Snidman, 1988). Behavioral inhibition is displayed very early in life; behaviorally inhibited toddlers and children respond with great caution and restraint in unfamiliar situations, and they are often timid, fearful, and shy around unfamiliar people (Fox, Henderson, Marshall, Nichols, & Ghera, 2005). A recent statistical review of studies demonstrated that behavioral inhibition was associated with more than a sevenfold increase in the risk of development of social anxiety disorder, demonstrating that behavioral inhibition is a major risk factor for the disorder (Clauss & Blackford, 2012). Panic Disorder Imagine that you are at the mall one day with your friends and—suddenly and inexplicably—you begin sweating and trembling, your heart starts pounding, you have trouble breathing, and you start to feel dizzy and nauseous. This episode lasts for 10 minutes and is terrifying because you start to think that you are going to die. When you visit your doctor the following morning and describe what happened, she tells you that you have experienced a panic attack ( Figure 15.9 ). If you experience another one of these episodes two weeks later and worry for a month or more that similar episodes will occur in the future, it is likely that you have developed panic disorder. People with panic disorder experience recurrent (more than one) and unexpected panic attacks, along with at least one month of persistent concern about additional panic attacks, worry over the consequences of the attacks, or self-defeating changes in behavior related to the attacks (e.g., avoidance of exercise or unfamiliar situations) (APA, 2013). As is the case with other anxiety disorders, the panic attacks cannot result from the physiological effects of drugs and other substances, a medical condition, or another mental disorder. A panic attack is defined as a period of extreme fear or discomfort that develops abruptly and reaches a peak within 10 minutes. Its symptoms include accelerated heart rate, sweating, trembling, choking sensations, hot flashes or chills, dizziness or lightheadedness, fears of losing control or going crazy, and fears of dying (APA, 2013). Sometimes panic attacks are expected, occurring in response to specific environmental triggers (such as being in a tunnel); other times, these episodes are unexpected and emerge randomly (such as when relaxing). According to the DSM-5, the person must experience unexpected panic attacks to qualify for a diagnosis of panic disorder. Experiencing a panic attack is often terrifying. Rather than recognizing the symptoms of a panic attack merely as signs of intense anxiety, individuals with panic disorder often misinterpret them as a sign that something is intensely wrong internally (thinking, for example, that the pounding heart represents an impending heart attack). Panic attacks can occasionally precipitate trips to the emergency room because several symptoms of panic attacks are, in fact, similar to those associated with heart problems (e.g., palpitations, racing pulse, and a pounding sensation in the chest) (Root, 2000). Unsurprisingly, those with panic disorder fear future attacks and may become preoccupied with modifying their behavior in an effort to avoid future panic attacks. For this reason, panic disorder is often characterized as fear of fear (Goldstein & Chambless, 1978). Panic attacks themselves are not mental disorders. Indeed, around 23% of Americans experience isolated panic attacks in their lives without meeting the criteria for panic disorder (Kessler et al., 2006), indicating that panic attacks are fairly common. Panic disorder is, of course, much less common, afflicting 4.7% of Americans during their lifetime (Kessler et al., 2005). Many people with panic disorder develop agoraphobia, which is marked by fear and avoidance of situations in which escape might be difficult or help might not be available if one were to develop symptoms of a panic attack. People with panic disorder often experience a comorbid disorder, such as other anxiety disorders or major depressive disorder (APA, 2013). Researchers are not entirely sure what causes panic disorder. Children are at a higher risk of developing panic disorder if their parents have the disorder (Biederman et al., 2001), and family and twins studies indicate that the heritability of panic disorder is around 43% (Hettema, Neale, & Kendler, 2001). The exact genes and gene functions involved in this disorder, however, are not well-understood (APA, 2013). Neurobiological theories of panic disorder suggest that a region of the brain called the locus coeruleus may play a role in this disorder. Located in the brainstem, the locus coeruleus is the brain’s major source of norepinephrine, a neurotransmitter that triggers the body’s fight-or-flight response. Activation of the locus coeruleus is associated with anxiety and fear, and research with nonhuman primates has shown that stimulating the locus coeruleus either electrically or through drugs produces panic-like symptoms (Charney et al., 1990). Such findings have led to the theory that panic disorder may be caused by abnormal norepinephrine activity in the locus coeruleus (Bremner, Krystal, Southwick, & Charney, 1996). Conditioning theories of panic disorder propose that panic attacks are classical conditioning responses to subtle bodily sensations resembling those normally occurring when one is anxious or frightened (Bouton, Mineka, & Barlow, 2001). For example, consider a child who has asthma. An acute asthma attack produces sensations, such as shortness of breath, coughing, and chest tightness, that typically elicit fear and anxiety. Later, when the child experiences subtle symptoms that resemble the frightening symptoms of earlier asthma attacks (such as shortness of breath after climbing stairs), he may become anxious, fearful, and then experience a panic attack. In this situation, the subtle symptoms would represent a conditioned stimulus, and the panic attack would be a conditioned response. The finding that panic disorder is nearly three times as frequent among people with asthma as it is among people without asthma (Weiser, 2007) supports the possibility that panic disorder has the potential to develop through classical conditioning. Cognitive factors may play an integral part in panic disorder. Generally, cognitive theories (Clark, 1996) argue that those with panic disorder are prone to interpret ordinary bodily sensations catastrophically, and these fearful interpretations set the stage for panic attacks. For example, a person might detect bodily changes that are routinely triggered by innocuous events such getting up from a seated position (dizziness), exercising (increased heart rate, shortness of breath), or drinking a large cup of coffee (increased heart rate, trembling). The individual interprets these subtle bodily changes catastrophically (“Maybe I’m having a heart attack!”). Such interpretations create fear and anxiety, which trigger additional physical symptoms; subsequently, the person experiences a panic attack. Support of this contention rests with findings that people with more severe catastrophic thoughts about sensations have more frequent and severe panic attacks, and among those with panic disorder, reducing catastrophic cognitions about their sensations is as effective as medication in reducing panic attacks (Good & Hinton, 2009). Generalized Anxiety Disorder Alex was always worried about many things. He worried that his children would drown when they played at the beach. Each time he left the house, he worried that an electrical short circuit would start a fire in his home. He worried that his wife would lose her job at the prestigious law firm. He worried that his daughter’s minor staph infection could turn into a massive life-threatening condition. These and other worries constantly weighed heavily on Alex’s mind, so much so that they made it difficult for him to make decisions and often left him feeling tense, irritable, and worn out. One night, Alex’s wife was to drive their son home from a soccer game. However, his wife stayed after the game and talked with some of the other parents, resulting in her arriving home 45 minutes late. Alex had tried to call his cell phone three or four times, but he could not get through because the soccer field did not have a signal. Extremely worried, Alex eventually called the police, convinced that his wife and son had not arrived home because they had been in a terrible car accident. Alex suffers from generalized anxiety disorder : a relatively continuous state of excessive, uncontrollable, and pointless worry and apprehension. People with generalized anxiety disorder often worry about routine, everyday things, even though their concerns are unjustified ( Figure 15.10 ). For example, an individual may worry about her health and finances, the health of family members, the safety of her children, or minor matters (e.g., being late for an appointment) without having any legitimate reason for doing so (APA, 2013). A diagnosis of generalized anxiety disorder requires that the diffuse worrying and apprehension characteristic of this disorder—what Sigmund Freud referred to as free-floating anxiety—is not part of another disorder, occurs more days than not for at least six months, and is accompanied by any three of the following symptoms: restlessness, difficulty concentrating, being easily fatigued, muscle tension, irritability, and sleep difficulties. About 5.7% of the U.S. population will develop symptoms of generalized anxiety disorder during their lifetime (Kessler et al., 2005), and females are 2 times as likely as males to experience the disorder (APA, 2013). Generalized anxiety disorder is highly comorbid with mood disorders and other anxiety disorders (Noyes, 2001), and it tends to be chronic. Also, generalized anxiety disorder appears to increase the risk for heart attacks and strokes, especially in people with preexisting heart conditions (Martens et al., 2010). Although there have been few investigations aimed at determining the heritability of generalized anxiety disorder, a summary of available family and twin studies suggests that genetic factors play a modest role in the disorder (Hettema et al., 2001). Cognitive theories of generalized anxiety disorder suggest that worry represents a mental strategy to avoid more powerful negative emotions (Aikins & Craske, 2001), perhaps stemming from earlier unpleasant or traumatic experiences. Indeed, one longitudinal study found that childhood maltreatment was strongly related to the development of this disorder during adulthood (Moffitt et al., 2007); worrying might distract people from remembering painful childhood experiences. 15.5 Obsessive-Compulsive and Related Disorders Learning Objectives By the end of this section, you will be able to: Describe the main features and prevalence of obsessive-compulsive disorder, body dysmorphic disorder, and hoarding disorder Understand some of the factors in the development of obsessive-compulsive disorder Obsessive-compulsive and related disorders are a group of overlapping disorders that generally involve intrusive, unpleasant thoughts and repetitive behaviors. Many of us experience unwanted thoughts from time to time (e.g., craving double cheeseburgers when dieting), and many of us engage in repetitive behaviors on occasion (e.g., pacing when nervous). However, obsessive-compulsive and related disorders elevate the unwanted thoughts and repetitive behaviors to a status so intense that these cognitions and activities disrupt daily life. Included in this category are obsessive-compulsive disorder (OCD), body dysmorphic disorder, and hoarding disorder. Obsessive-Compulsive Disorder People with obsessive-compulsive disorder (OCD) experience thoughts and urges that are intrusive and unwanted (obsessions) and/or the need to engage in repetitive behaviors or mental acts (compulsions). A person with this disorder might, for example, spend hours each day washing his hands or constantly checking and rechecking to make sure that a stove, faucet, or light has been turned off. Obsessions are more than just unwanted thoughts that seem to randomly jump into our head from time to time, such as recalling an insensitive remark a coworker made recently, and they are more significant than day-to-day worries we might have, such as justifiable concerns about being laid off from a job. Rather, obsessions are characterized as persistent, unintentional, and unwanted thoughts and urges that are highly intrusive, unpleasant, and distressing (APA, 2013). Common obsessions include concerns about germs and contamination, doubts (“Did I turn the water off?”), order and symmetry (“I need all the spoons in the tray to be arranged a certain way”), and urges that are aggressive or lustful. Usually, the person knows that such thoughts and urges are irrational and thus tries to suppress or ignore them, but has an extremely difficult time doing so. These obsessive symptoms sometimes overlap, such that someone might have both contamination and aggressive obsessions (Abramowitz & Siqueland, 2013). Compulsions are repetitive and ritualistic acts that are typically carried out primarily as a means to minimize the distress that obsessions trigger or to reduce the likelihood of a feared event (APA, 2013). Compulsions often include such behaviors as repeated and extensive hand washing, cleaning, checking (e.g., that a door is locked), and ordering (e.g., lining up all the pencils in a particular way), and they also include such mental acts as counting, praying, or reciting something to oneself ( Figure 15.11 ). Compulsions characteristic of OCD are not performed out of pleasure, nor are they connected in a realistic way to the source of the distress or feared event. Approximately 2.3% of the U.S. population will experience OCD in their lifetime (Ruscio, Stein, Chiu, & Kessler, 2010) and, if left untreated, OCD tends to be a chronic condition creating lifelong interpersonal and psychological problems (Norberg, Calamari, Cohen, & Riemann, 2008). Body Dysmorphic Disorder An individual with body dysmorphic disorder is preoccupied with a perceived flaw in her physical appearance that is either nonexistent or barely noticeable to other people (APA, 2013). These perceived physical defects cause the person to think she is unattractive, ugly, hideous, or deformed. These preoccupations can focus on any bodily area, but they typically involve the skin, face, or hair. The preoccupation with imagined physical flaws drives the person to engage in repetitive and ritualistic behavioral and mental acts, such as constantly looking in the mirror, trying to hide the offending body part, comparisons with others, and, in some extreme cases, cosmetic surgery (Phillips, 2005). An estimated 2.4% of the adults in the United States meet the criteria for body dysmorphic disorder, with slightly higher rates in women than in men (APA, 2013). Hoarding Disorder Although hoarding was traditionally considered to be a symptom of OCD, considerable evidence suggests that hoarding represents an entirely different disorder (Mataix-Cols et al., 2010). People with hoarding disorder cannot bear to part with personal possessions, regardless of how valueless or useless these possessions are. As a result, these individuals accumulate excessive amounts of usually worthless items that clutter their living areas ( Figure 15.12 ). Often, the quantity of cluttered items is so excessive that the person is unable use his kitchen, or sleep in his bed. People who suffer from this disorder have great difficulty parting with items because they believe the items might be of some later use, or because they form a sentimental attachment to the items (APA, 2013). Importantly, a diagnosis of hoarding disorder is made only if the hoarding is not caused by another medical condition and if the hoarding is not a symptom of another disorder (e.g., schizophrenia) (APA, 2013). Causes of OCD The results of family and twin studies suggest that OCD has a moderate genetic component. The disorder is five times more frequent in the first-degree relatives of people with OCD than in people without the disorder (Nestadt et al., 2000). Additionally, the concordance rate of OCD among identical twins is around 57%; however, the concordance rate for fraternal twins is 22% (Bolton, Rijsdijk, O’Connor, Perrin, & Eley, 2007). Studies have implicated about two dozen potential genes that may be involved in OCD; these genes regulate the function of three neurotransmitters: serotonin, dopamine, and glutamate (Pauls, 2010). Many of these studies included small sample sizes and have yet to be replicated. Thus, additional research needs to be done in this area. A brain region that is believed to play a critical role in OCD is the orbitofrontal cortex (Kopell & Greenberg, 2008), an area of the frontal lobe involved in learning and decision-making (Rushworth, Noonan, Boorman, Walton, & Behrens, 2011) ( Figure 15.13 ). In people with OCD, the orbitofrontal cortex becomes especially hyperactive when they are provoked with tasks in which, for example, they are asked to look at a photo of a toilet or of pictures hanging crookedly on a wall (Simon, Kaufmann, Müsch, Kischkel, & Kathmann, 2010). The orbitofrontal cortex is part of a series of brain regions that, collectively, is called the OCD circuit; this circuit consists of several interconnected regions that influence the perceived emotional value of stimuli and the selection of both behavioral and cognitive responses (Graybiel & Rauch, 2000). As with the orbitofrontal cortex, other regions of the OCD circuit show heightened activity during symptom provocation (Rotge et al., 2008), which suggests that abnormalities in these regions may produce the symptoms of OCD (Saxena, Bota, & Brody, 2001). Consistent with this explanation, people with OCD show a substantially higher degree of connectivity of the orbitofrontal cortex and other regions of the OCD circuit than do those without OCD (Beucke et al., 2013). The findings discussed above were based on imaging studies, and they highlight the potential importance of brain dysfunction in OCD. However, one important limitation of these findings is the inability to explain differences in obsessions and compulsions. Another limitation is that the correlational relationship between neurological abnormalities and OCD symptoms cannot imply causation (Abramowitz & Siqueland, 2013). Connect the Concepts Conditioning and OCD The symptoms of OCD have been theorized to be learned responses, acquired and sustained as the result of a combination of two forms of learning: classical conditioning and operant conditioning (Mowrer, 1960; Steinmetz, Tracy, & Green, 2001). Specifically, the acquisition of OCD may occur first as the result of classical conditioning, whereby a neutral stimulus becomes associated with an unconditioned stimulus that provokes anxiety or distress. When an individual has acquired this association, subsequent encounters with the neutral stimulus trigger anxiety, including obsessive thoughts; the anxiety and obsessive thoughts (which are now a conditioned response) may persist until she identifies some strategy to relieve it. Relief may take the form of a ritualistic behavior or mental activity that, when enacted repeatedly, reduces the anxiety. Such efforts to relieve anxiety constitute an example of negative reinforcement (a form of operant conditioning). Recall from the chapter on learning that negative reinforcement involves the strengthening of behavior through its ability to remove something unpleasant or aversive. Hence, compulsive acts observed in OCD may be sustained because they are negatively reinforcing, in the sense that they reduce anxiety triggered by a conditioned stimulus. Suppose an individual with OCD experiences obsessive thoughts about germs, contamination, and disease whenever she encounters a doorknob. What might have constituted a viable unconditioned stimulus? Also, what would constitute the conditioned stimulus, unconditioned response, and conditioned response? What kinds of compulsive behaviors might we expect, and how do they reinforce themselves? What is decreased? Additionally, and from the standpoint of learning theory, how might the symptoms of OCD be treated successfully? 15.6 Posttraumatic Stress Disorder Learning Objectives By the end of this section, you will be able to: Describe the nature and symptoms of posttraumatic stress disorder Identify the risk factors associated with this disorder Understand the role of learning and cognitive factors in its development Extremely stressful or traumatic events, such as combat, natural disasters, and terrorist attacks, place the people who experience them at an increased risk for developing psychological disorders such as posttraumatic stress disorder (PTSD) . Throughout much of the 20th century, this disorder was called shell shock and combat neurosis because its symptoms were observed in soldiers who had engaged in wartime combat. By the late 1970s it had become clear that women who had experienced sexual traumas (e.g., rape, domestic battery, and incest) often experienced the same set of symptoms as did soldiers (Herman, 1997). The term posttraumatic stress disorder was developed given that these symptoms could happen to anyone who experienced psychological trauma. A Broader Definition of PTSD PTSD was listed among the anxiety disorders in previous DSM editions. In DSM-5, it is now listed among a group called Trauma-and-Stressor-Related Disorders. For a person to be diagnosed with PTSD, she must be exposed to, witness, or experience the details of a traumatic experience (e.g., a first responder), one that involves “actual or threatened death, serious injury, or sexual violence” (APA, 2013, p. 271). These experiences can include such events as combat, threatened or actual physical attack, sexual assault, natural disasters, terrorist attacks, and automobile accidents. This criterion makes PTSD the only disorder listed in the DSM in which a cause (extreme trauma) is explicitly specified. Symptoms of PTSD include intrusive and distressing memories of the event, flashbacks (states that can last from a few seconds to several days, during which the individual relives the event and behaves as if the event were occurring at that moment [APA, 2013]), avoidance of stimuli connected to the event, persistently negative emotional states (e.g., fear, anger, guilt, and shame), feelings of detachment from others, irritability, proneness toward outbursts, and an exaggerated startle response (jumpiness). For PTSD to be diagnosed, these symptoms must occur for at least one month. Roughly 7% of adults in the United States, including 9.7% of women and 3.6% of men, experience PTSD in their lifetime (National Comorbidity Survey, 2007), with higher rates among people exposed to mass trauma and people whose jobs involve duty-related trauma exposure (e.g., police officers, firefighters, and emergency medical personnel) (APA, 2013). Nearly 21% of residents of areas affected by Hurricane Katrina suffered from PTSD one year following the hurricane (Kessler et al., 2008), and 12.6% of Manhattan residents were observed as having PTSD 2–3 years after the 9/11 terrorist attacks (DiGrande et al., 2008). Risk Factors For PTSD Of course, not everyone who experiences a traumatic event will go on to develop PTSD; several factors strongly predict the development of PTSD: trauma experience, greater trauma severity, lack of immediate social support, and more subsequent life stress (Brewin, Andrews, & Valentine, 2000). Traumatic events that involve harm by others (e.g., combat, rape, and sexual molestation) carry greater risk than do other traumas (e.g., natural disasters) (Kessler, Sonnega, Bromet, Hughes, & Nelson, 1995). Factors that increase the risk of PTSD include female gender, low socioeconomic status, low intelligence, personal history of mental disorders, history of childhood adversity (abuse or other trauma during childhood), and family history of mental disorders (Brewin et al., 2000). Personality characteristics such as neuroticism and somatization (the tendency to experience physical symptoms when one encounters stress) have been shown to elevate the risk of PTSD (Bramsen, Dirkzwager, & van der Ploeg, 2000). People who experience childhood adversity and/or traumatic experiences during adulthood are at significantly higher risk of developing PTSD if they possess one or two short versions of a gene that regulates the neurotransmitter serotonin (Xie et al., 2009). This suggests a possible diathesis-stress interpretation of PTSD: its development is influenced by the interaction of psychosocial and biological factors. Support For Sufferers of PTSD Research has shown that social support following a traumatic event can reduce the likelihood of PTSD (Ozer, Best, Lipsey, & Weiss, 2003). Social support is often defined as the comfort, advice, and assistance received from relatives, friends, and neighbors. Social support can help individuals cope during difficult times by allowing them to discuss feelings and experiences and providing a sense of being loved and appreciated. A 14-year study of 1,377 American Legionnaires who had served in the Vietnam War found that those who perceived less social support when they came home were more likely to develop PTSD than were those who perceived greater support ( Figure 15.14 ). In addition, those who became involved in the community were less likely to develop PTSD, and they were more likely to experience a remission of PTSD than were those who were less involved (Koenen, Stellman, Stellman, & Sommer, 2003). Learning and the Development of PTSD PTSD learning models suggest that some symptoms are developed and maintained through classical conditioning. The traumatic event may act as an unconditioned stimulus that elicits an unconditioned response characterized by extreme fear and anxiety. Cognitive, emotional, physiological, and environmental cues accompanying or related to the event are conditioned stimuli. These traumatic reminders evoke conditioned responses (extreme fear and anxiety) similar to those caused by the event itself (Nader, 2001). A person who was in the vicinity of the Twin Towers during the 9/11 terrorist attacks and who developed PTSD may display excessive hypervigilance and distress when planes fly overhead; this behavior constitutes a conditioned response to the traumatic reminder (conditioned stimulus of the sight and sound of an airplane). Differences in how conditionable individuals are help to explain differences in the development and maintenance of PTSD symptoms (Pittman, 1988). Conditioning studies demonstrate facilitated acquisition of conditioned responses and delayed extinction of conditioned responses in people with PTSD (Orr et al., 2000). Cognitive factors are important in the development and maintenance of PTSD. One model suggests that two key processes are crucial: disturbances in memory for the event, and negative appraisals of the trauma and its aftermath (Ehlers & Clark, 2000). According to this theory, some people who experience traumas do not form coherent memories of the trauma; memories of the traumatic event are poorly encoded and, thus, are fragmented, disorganized, and lacking in detail. Therefore, these individuals are unable remember the event in a way that gives it meaning and context. A rape victim who cannot coherently remember the event may remember only bits and pieces (e.g., the attacker repeatedly telling her she is stupid); because she was unable to develop a fully integrated memory, the fragmentary memory tends to stand out. Although unable to retrieve a complete memory of the event, she may be haunted by intrusive fragments involuntarily triggered by stimuli associated with the event (e.g., memories of the attacker’s comments when encountering a person who resembles the attacker). This interpretation fits previously discussed material concerning PTSD and conditioning. The model also proposes that negative appraisals of the event (“I deserved to be raped because I’m stupid”) may lead to dysfunctional behavioral strategies (e.g., avoiding social activities where men are likely to be present) that maintain PTSD symptoms by preventing both a change in the nature of the memory and a change in the problematic appraisals. 15.7 Mood Disorders Learning Objectives By the end of this section, you will be able to: Distinguish normal states of sadness and euphoria from states of depression and mania Describe the symptoms of major depressive disorder and bipolar disorder Understand the differences between major depressive disorder and persistent depressive disorder, and identify two subtypes of depression Define the criteria for a manic episode Understand genetic, biological, and psychological explanations of major depressive disorder Discuss the relationship between mood disorders and suicidal ideation, as well as factors associated with suicide Blake cries all day and feeling that he is worthless and his life is hopeless, he cannot get out of bed. Crystal stays up all night, talks very rapidly, and went on a shopping spree in which she spent $3,000 on furniture, although she cannot afford it. Maria recently had a baby, and she feels overwhelmed, teary, anxious, and panicked, and believes she is a terrible mother—practically every day since the baby was born. All these individuals demonstrate symptoms of a potential mood disorder. Mood disorders ( Figure 15.15 ) are characterized by severe disturbances in mood and emotions—most often depression, but also mania and elation (Rothschild, 1999). All of us experience fluctuations in our moods and emotional states, and often these fluctuations are caused by events in our lives. We become elated if our favorite team wins the World Series and dejected if a romantic relationship ends or if we lose our job. At times, we feel fantastic or miserable for no clear reason. People with mood disorders also experience mood fluctuations, but their fluctuations are extreme, distort their outlook on life, and impair their ability to function. The DSM-5 lists two general categories of mood disorders. Depressive disorders are a group of disorders in which depression is the main feature. Depression is a vague term that, in everyday language, refers to an intense and persistent sadness. Depression is a heterogeneous mood state—it consists of a broad spectrum of symptoms that range in severity. Depressed people feel sad, discouraged, and hopeless. These individuals lose interest in activities once enjoyed, often experience a decrease in drives such as hunger and sex, and frequently doubt personal worth. Depressive disorders vary by degree, but this chapter highlights the most well-known: major depressive disorder (sometimes called unipolar depression). Bipolar and related disorders are a group of disorders in which mania is the defining feature. Mania is a state of extreme elation and agitation. When people experience mania, they may become extremely talkative, behave recklessly, or attempt to take on many tasks simultaneously. The most recognized of these disorders is bipolar disorder. Major Depressive Disorder According to the DSM-5, the defining symptoms of major depressive disorder include “depressed mood most of the day, nearly every day” (feeling sad, empty, hopeless, or appearing tearful to others), and loss of interest and pleasure in usual activities (APA, 2013). In addition to feeling overwhelmingly sad most of each day, people with depression will no longer show interest or enjoyment in activities that previously were gratifying, such as hobbies, sports, sex, social events, time spent with family, and so on. Friends and family members may notice that the person has completely abandoned previously enjoyed hobbies; for example, an avid tennis player who develops major depressive disorder no longer plays tennis (Rothschild, 1999). To receive a diagnosis of major depressive disorder, one must experience a total of five symptoms for at least a two-week period; these symptoms must cause significant distress or impair normal functioning, and they must not be caused by substances or a medical condition. At least one of the two symptoms mentioned above must be present, plus any combination of the following symptoms (APA, 2013): significant weight loss (when not dieting) or weight gain and/or significant decrease or increase in appetite; difficulty falling asleep or sleeping too much; psychomotor agitation (the person is noticeably fidgety and jittery, demonstrated by behaviors like the inability to sit, pacing, hand-wringing, pulling or rubbing of the skin, clothing, or other objects) or psychomotor retardation (the person talks and moves slowly, for example, talking softly, very little, or in a monotone); fatigue or loss of energy; feelings of worthlessness or guilt; difficulty concentrating and indecisiveness; and suicidal ideation : thoughts of death (not just fear of dying), thinking about or planning suicide, or making an actual suicide attempt. Major depressive disorder is considered episodic: its symptoms are typically present at their full magnitude for a certain period of time and then gradually abate. Approximately 50%–60% of people who experience an episode of major depressive disorder will have a second episode at some point in the future; those who have had two episodes have a 70% chance of having a third episode, and those who have had three episodes have a 90% chance of having a fourth episode (Rothschild, 1999). Although the episodes can last for months, a majority a people diagnosed with this condition (around 70%) recover within a year. However, a substantial number do not recover; around 12% show serious signs of impairment associated with major depressive disorder after 5 years (Boland & Keller, 2009). In the long-term, many who do recover will still show minor symptoms that fluctuate in their severity (Judd, 2012). Results of Major Depressive Disorder Major depressive disorder is a serious and incapacitating condition that can have a devastating effect on the quality of one’s life. The person suffering from this disorder lives a profoundly miserable existence that often results in unavailability for work or education, abandonment of promising careers, and lost wages; occasionally, the condition requires hospitalization. The majority of those with major depressive disorder report having faced some kind of discrimination, and many report that having received such treatment has stopped them from initiating close relationships, applying for jobs for which they are qualified, and applying for education or training (Lasalvia et al., 2013). Major depressive disorder also takes a toll on health. Depression is a risk factor for the development of heart disease in healthy patients, as well as adverse cardiovascular outcomes in patients with preexisting heart disease (Whooley, 2006). Risk Factors for Major Depressive Disorder Major depressive disorder is often referred to as the common cold of psychiatric disorders. Around 6.6% of the U.S. population experiences major depressive disorder each year; 16.9% will experience the disorder during their lifetime (Kessler & Wang, 2009). It is more common among women than among men, affecting approximately 20% of women and 13% of men at some point in their life (National Comorbidity Survey, 2007). The greater risk among women is not accounted for by a tendency to report symptoms or to seek help more readily, suggesting that gender differences in the rates of major depressive disorder may reflect biological and gender-related environmental experiences (Kessler, 2003). Lifetime rates of major depressive disorder tend to be highest in North and South America, Europe, and Australia; they are considerably lower in Asian countries (Hasin, Fenton, & Weissman, 2011). The rates of major depressive disorder are higher among younger age cohorts than among older cohorts, perhaps because people in younger age cohorts are more willing to admit depression (Kessler & Wang, 2009). A number of risk factors are associated with major depressive disorder: unemployment (including homemakers); earning less than $20,000 per year; living in urban areas; or being separated, divorced, or widowed (Hasin et al., 2011). Comorbid disorders include anxiety disorders and substance abuse disorders (Kessler & Wang, 2009). Subtypes of Depression The DSM-5 lists several different subtypes of depression. These subtypes—what the DSM-5 refer to as specifiers—are not specific disorders; rather, they are labels used to indicate specific patterns of symptoms or to specify certain periods of time in which the symptoms may be present. One subtype, seasonal pattern , applies to situations in which a person experiences the symptoms of major depressive disorder only during a particular time of year (e.g., fall or winter). In everyday language, people often refer to this subtype as the winter blues. Another subtype, peripartum onset (commonly referred to as postpartum depression ), applies to women who experience major depression during pregnancy or in the four weeks following the birth of their child (APA, 2013). These women often feel very anxious and may even have panic attacks. They may feel guilty, agitated, and be weepy. They may not want to hold or care for their newborn, even in cases in which the pregnancy was desired and intended. In extreme cases, the mother may have feelings of wanting to harm her child or herself. In a horrific illustration, a woman named Andrea Yates, who suffered from extreme peripartum-onset depression (as well as other mental illnesses), drowned her five children in a bathtub (Roche, 2002). Most women with peripartum-onset depression do not physically harm their children, but most do have difficulty being adequate caregivers (Fields, 2010). A surprisingly high number of women experience symptoms of peripartum-onset depression. A study of 10,000 women who had recently given birth found that 14% screened positive for peripartum-onset depression, and that nearly 20% reported having thoughts of wanting to harm themselves (Wisner et al., 2013). People with persistent depressive disorder (previously known as dysthymia) experience depressed moods most of the day nearly every day for at least two years, as well as at least two of the other symptoms of major depressive disorder. People with persistent depressive disorder are chronically sad and melancholy, but do not meet all the criteria for major depression. However, episodes of full-blown major depressive disorder can occur during persistent depressive disorder (APA, 2013). Bipolar Disorder A person with bipolar disorder (commonly known as manic depression ) often experiences mood states that vacillate between depression and mania; that is, the person’s mood is said to alternate from one emotional extreme to the other (in contrast to unipolar, which indicates a persistently sad mood). To be diagnosed with bipolar disorder, a person must have experienced a manic episode at least once in his life; although major depressive episodes are common in bipolar disorder, they are not required for a diagnosis (APA, 2013). According to the DSM-5, a manic episode is characterized as a “distinct period of abnormally and persistently elevated, expansive, or irritable mood and abnormally and persistently increased activity or energy lasting at least one week,” that lasts most of the time each day (APA, 2013, p. 124). During a manic episode, some experience a mood that is almost euphoric and become excessively talkative, sometimes spontaneously starting conversations with strangers; others become excessively irritable and complain or make hostile comments. The person may talk loudly and rapidly, exhibiting flight of ideas , abruptly switching from one topic to another. These individuals are easily distracted, which can make a conversation very difficult. They may exhibit grandiosity, in which they experience inflated but unjustified self-esteem and self-confidence. For example, they might quit a job in order to “strike it rich” in the stock market, despite lacking the knowledge, experience, and capital for such an endeavor. They may take on several tasks at the same time (e.g., several time-consuming projects at work) and yet show little, if any, need for sleep; some may go for days without sleep. Patients may also recklessly engage in pleasurable activities that could have harmful consequences, including spending sprees, reckless driving, making foolish investments, excessive gambling, or engaging in sexual encounters with strangers (APA, 2013). During a manic episode, individuals usually feel as though they are not ill and do not need treatment. However, the reckless behaviors that often accompany these episodes—which can be antisocial, illegal, or physically threatening to others—may require involuntary hospitalization (APA, 2013). Some patients with bipolar disorder will experience a rapid-cycling subtype, which is characterized by at least four manic episodes (or some combination of at least four manic and major depressive episodes) within one year. Link to Learning In the 1997 independent film Sweetheart , actress Janeane Garofalo plays the part of Jasmine, a young woman with bipolar disorder. Watch this firsthand account from a person living with bipolar disorder. Risk Factors for Bipolar Disorder Bipolar disorder is considerably less frequent than major depressive disorder. In the United States, 1 out of every 167 people meets the criteria for bipolar disorder each year, and 1 out of 100 meet the criteria within their lifetime (Merikangas et al., 2011). The rates are higher in men than in women, and about half of those with this disorder report onset before the age of 25 (Merikangas et al., 2011). Around 90% of those with bipolar disorder have a comorbid disorder, most often an anxiety disorder or a substance abuse problem. Unfortunately, close to half of the people suffering from bipolar disorder do not receive treatment (Merikangas & Tohen, 2011). Suicide rates are extremely high among those with bipolar disorder: around 36% of individuals with this disorder attempt suicide at least once in their lifetime (Novick, Swartz, & Frank, 2010), and between 15%–19% complete suicide (Newman, 2004). The Biological Basis of Mood Disorders Mood disorders have been shown to have a strong genetic and biological basis. Relatives of those with major depressive disorder have double the risk of developing major depressive disorder, whereas relatives of patients with bipolar disorder have over nine times the risk (Merikangas et al., 2011). The rate of concordance for major depressive disorder is higher among identical twins than fraternal twins (50% vs. 38%, respectively), as is that of bipolar disorder (67% vs. 16%, respectively), suggesting that genetic factors play a stronger role in bipolar disorder than in major depressive disorder (Merikangas et al. 2011). People with mood disorders often have imbalances in certain neurotransmitters, particularly norepinephrine and serotonin (Thase, 2009). These neurotransmitters are important regulators of the bodily functions that are disrupted in mood disorders, including appetite, sex drive, sleep, arousal, and mood. Medications that are used to treat major depressive disorder typically boost serotonin and norepinephrine activity, whereas lithium—used in the treatment of bipolar disorder—blocks norepinephrine activity at the synapses ( Figure 15.16 ). Depression is linked to abnormal activity in several regions of the brain (Fitzgerald, Laird, Maller, & Daskalakis, 2008) including those important in assessing the emotional significance of stimuli and experiencing emotions (amygdala), and in regulating and controlling emotions (like the prefrontal cortex, or PFC) (LeMoult, Castonguay, Joormann, & McAleavey, 2013). Depressed individuals show elevated amygdala activity (Drevets, Bogers, & Raichle, 2002), especially when presented with negative emotional stimuli, such as photos of sad faces ( Figure 15.17 ) (Surguladze et al., 2005). Interestingly, heightened amygdala activation to negative emotional stimuli among depressed persons occurs even when stimuli are presented outside of conscious awareness (Victor, Furey, Fromm, Öhman, & Drevets, 2010), and it persists even after the negative emotional stimuli are no longer present (Siegle, Thompson, Carter, Steinhauer, & Thase, 2007). Additionally, depressed individuals exhibit less activation in the prefrontal, particularly on the left side (Davidson, Pizzagalli, & Nitschke, 2009). Because the PFC can dampen amygdala activation, thereby enabling one to suppress negative emotions (Phan et al., 2005), decreased activation in certain regions of the PFC may inhibit its ability to override negative emotions that might then lead to more negative mood states (Davidson et al., 2009). These findings suggest that depressed persons are more prone to react to emotionally negative stimuli, yet have greater difficulty controlling these reactions. Since the 1950s, researchers have noted that depressed individuals have abnormal levels of cortisol, a stress hormone released into the blood by the neuroendocrine system during times of stress (Mackin & Young, 2004). When cortisol is released, the body initiates a fight-or-flight response in reaction to a threat or danger. Many people with depression show elevated cortisol levels (Holsboer & Ising, 2010), especially those reporting a history of early life trauma such as the loss of a parent or abuse during childhood (Baes, Tofoli, Martins, & Juruena, 2012). Such findings raise the question of whether high cortisol levels are a cause or a consequence of depression. High levels of cortisol are a risk factor for future depression (Halligan, Herbert, Goodyer, & Murray, 2007), and cortisol activates activity in the amygdala while deactivating activity in the PFC (McEwen, 2005)—both brain disturbances are connected to depression. Thus, high cortisol levels may have a causal effect on depression, as well as on its brain function abnormalities (van Praag, 2005). Also, because stress results in increased cortisol release (Michaud, Matheson, Kelly, Anisman, 2008), it is equally reasonable to assume that stress may precipitate depression. A Diathesis-Stress Model and Major Depressive Disorders Indeed, it has long been believed that stressful life events can trigger depression, and research has consistently supported this conclusion (Mazure, 1998). Stressful life events include significant losses, such as death of a loved one, divorce or separation, and serious health and money problems; life events such as these often precede the onset of depressive episodes (Brown & Harris, 1989). In particular, exit events—instances in which an important person departs (e.g., a death, divorce or separation, or a family member leaving home)—often occur prior to an episode (Paykel, 2003). Exit events are especially likely to trigger depression if these happenings occur in a way that humiliates or devalues the individual. For example, people who experience the breakup of a relationship initiated by the other person develop major depressive disorder at a rate more than 2 times that of people who experience the death of a loved one (Kendler, Hettema, Butera, Gardner, & Prescott, 2003). Likewise, individuals who are exposed to traumatic stress during childhood—such as separation from a parent, family turmoil, and maltreatment (physical or sexual abuse)—are at a heightened risk of developing depression at any point in their lives (Kessler, 1997). A recent review of 16 studies involving over 23,000 subjects concluded that those who experience childhood maltreatment are more than 2 times as likely to develop recurring and persistent depression (Nanni, Uher, & Danese, 2012). Of course, not everyone who experiences stressful life events or childhood adversities succumbs to depression—indeed, most do not. Clearly, a diathesis-stress interpretation of major depressive disorder, in which certain predispositions or vulnerability factors influence one’s reaction to stress, would seem logical. If so, what might such predispositions be? A study by Caspi and others (2003) suggests that an alteration in a specific gene that regulates serotonin (the 5-HTTLPR gene) might be one culprit. These investigators found that people who experienced several stressful life events were significantly more likely to experience episodes of major depression if they carried one or two short versions of this gene than if they carried two long versions. Those who carried one or two short versions of the 5-HTTLPR gene were unlikely to experience an episode, however, if they had experienced few or no stressful life events. Numerous studies have replicated these findings, including studies of people who experienced maltreatment during childhood (Goodman & Brand, 2009). In a recent investigation conducted in the United Kingdom (Brown & Harris, 2013), researchers found that childhood maltreatment before age 9 elevated the risk of chronic adult depression (a depression episode lasting for at least 12 months) among those individuals having one (LS) or two (SS) short versions of the 5-HTTLPR gene ( Figure 15.18 ). Childhood maltreatment did not increase the risk for chronic depression for those have two long (LL) versions of this gene. Thus, genetic vulnerability may be one mechanism through which stress potentially leads to depression. Cognitive Theories of Depression Cognitive theories of depression take the view that depression is triggered by negative thoughts, interpretations, self-evaluations, and expectations (Joormann, 2009). These diathesis-stress models propose that depression is triggered by a “cognitive vulnerability” (negative and maladaptive thinking) and by precipitating stressful life events (Gotlib & Joormann, 2010). Perhaps the most well-known cognitive theory of depression was developed in the 1960s by psychiatrist Aaron Beck, based on clinical observations and supported by research (Beck, 2008). Beck theorized that depression-prone people possess depressive schemas, or mental predispositions to think about most things in a negative way (Beck, 1976). Depressive schemas contain themes of loss, failure, rejection, worthlessness, and inadequacy, and may develop early in childhood in response to adverse experiences, then remain dormant until they are activated by stressful or negative life events. Depressive schemas prompt dysfunctional and pessimistic thoughts about the self, the world, and the future. Beck believed that this dysfunctional style of thinking is maintained by cognitive biases, or errors in how we process information about ourselves, which lead us to focus on negative aspects of experiences, interpret things negatively, and block positive memories (Beck, 2008). A person whose depressive schema consists of a theme of rejection might be overly attentive to social cues of rejection (more likely to notice another’s frown), and he might interpret this cue as a sign of rejection and automatically remember past incidents of rejection. Longitudinal studies have supported Beck’s theory, in showing that a preexisting tendency to engage in this negative, self-defeating style of thinking—when combined with life stress—over time predicts the onset of depression (Dozois & Beck, 2008). Cognitive therapies for depression, aimed at changing a depressed person’s negative thinking, were developed as an expansion of this theory (Beck, 1976). Another cognitive theory of depression, hopelessness theory , postulates that a particular style of negative thinking leads to a sense of hopelessness, which then leads to depression (Abramson, Metalsky, & Alloy, 1989). According to this theory, hopelessness is an expectation that unpleasant outcomes will occur or that desired outcomes will not occur, and there is nothing one can do to prevent such outcomes. A key assumption of this theory is that hopelessness stems from a tendency to perceive negative life events as having stable (“It’s never going to change”) and global (“It’s going to affect my whole life”) causes, in contrast to unstable (“It’s fixable”) and specific (“It applies only to this particular situation”) causes, especially if these negative life events occur in important life realms, such as relationships, academic achievement, and the like. Suppose a student who wishes to go to law school does poorly on an admissions test. If the student infers negative life events as having stable and global causes, she may believe that her poor performance has a stable and global cause (“I lack intelligence, and it’s going to prevent me from ever finding a meaningful career”), as opposed to an unstable and specific cause (“I was sick the day of the exam, so my low score was a fluke”). Hopelessness theory predicts that people who exhibit this cognitive style in response to undesirable life events will view such events as having negative implications for their future and self-worth, thereby increasing the likelihood of hopelessness—the primary cause of depression (Abramson et al., 1989). One study testing hopelessness theory measured the tendency to make negative inferences for bad life effects in participants who were experiencing uncontrollable stressors. Over the ensuing six months, those with scores reflecting high cognitive vulnerability were 7 times more likely to develop depression compared to those with lower scores (Kleim, Gonzalo, & Ehlers, 2011). A third cognitive theory of depression focuses on how people’s thoughts about their distressed moods—depressed symptoms in particular—can increase the risk and duration of depression. This theory, which focuses on rumination in the development of depression, was first described in the late 1980s to explain the higher rates of depression in women than in men (Nolen-Hoeksema, 1987). Rumination is the repetitive and passive focus on the fact that one is depressed and dwelling on depressed symptoms, rather that distracting one’s self from the symptoms or attempting to address them in an active, problem-solving manner (Nolen-Hoeksema, 1991). When people ruminate, they have thoughts such as “Why am I so unmotivated? I just can’t get going. I’m never going to get my work done feeling this way” (Nolen-Hoeksema & Hilt, 2009, p. 393). Women are more likely than men to ruminate when they are sad or depressed (Butler & Nolen-Hoeksema, 1994), and the tendency to ruminate is associated with increases in depression symptoms (Nolen-Hoeksema, Larson, & Grayson, 1999), heightened risk of major depressive episodes (Abela & Hankin, 2011), and chronicity of such episodes (Robinson & Alloy, 2003) Suicide For some people with mood disorders, the extreme emotional pain they experience becomes unendurable. Overwhelmed by hopelessness, devastated by incapacitating feelings of worthlessness, and burdened with the inability to adequately cope with such feelings, they may consider suicide to be a reasonable way out. Suicide , defined by the CDC as “death caused by self-directed injurious behavior with any intent to die as the result of the behavior” (CDC, 2013a), in a sense represents an outcome of several things going wrong all at the same time Crosby, Ortega, & Melanson, 2011). Not only must the person be biologically or psychologically vulnerable, but he must also have the means to perform the suicidal act, and he must lack the necessary protective factors (e.g., social support from friends and family, religion, coping skills, and problem-solving skills) that provide comfort and enable one to cope during times of crisis or great psychological pain (Berman, 2009). Suicide is not listed as a disorder in the DSM-5; however, suffering from a mental disorder—especially a mood disorder—poses the greatest risk for suicide. Around 90% of those who complete suicides have a diagnosis of at least one mental disorder, with mood disorders being the most frequent (Fleischman, Bertolote, Belfer, & Beautrais, 2005). In fact, the association between major depressive disorder and suicide is so strong that one of the criteria for the disorder is thoughts of suicide, as discussed above (APA, 2013). Suicide rates can be difficult to interpret because some deaths that appear to be accidental may in fact be acts of suicide (e.g., automobile crash). Nevertheless, investigations into U.S. suicide rates have uncovered these facts: Suicide was the 10th leading cause of death for all ages in 2010 (Centers for Disease Control and Prevention [CDC], 2012). There were 38,364 suicides in 2010 in the United States—an average of 105 each day (CDC, 2012). Suicide among males is 4 times higher than among females and accounts for 79% of all suicides; firearms are the most commonly used method of suicide for males, whereas poisoning is the most commonly used method for females (CDC, 2012). From 1991 to 2003, suicide rates were consistently higher among those 65 years and older. Since 2001, however, suicide rates among those ages 25–64 have risen consistently, and, since 2006, suicide rates have been greater for those ages 65 and older (CDC, 2013b). This increase in suicide rates among middle-aged Americans has prompted concern in some quarters that baby boomers (individuals born between 1946–1964) who face economic worry and easy access to prescription medication may be particularly vulnerable to suicide (Parker-Pope, 2013). The highest rates of suicide within the United States are among American Indians/Alaskan natives and Non-Hispanic Whites (CDC, 2013b). Suicide rates vary across the United States, with the highest rates consistently found in the mountain states of the west (Alaska, Montana, Nevada, Wyoming, Colorado, and Idaho) (Berman, 2009). Contrary to popular belief, suicide rates peak during the springtime (April and May), not during the holiday season or winter. In fact, suicide rates are generally lowest during the winter months (Postolache et al., 2010). Risk Factors For Suicide Suicidal risk is especially high among people with substance abuse problems. Individuals with alcohol dependence are at 10 times greater risk for suicide than the general population (Wilcox, Conner, & Caine, 2004). The risk of suicidal behavior is especially high among those who have made a prior suicide attempt. Among those who attempt suicide, 16% make another attempt within a year and over 21% make another attempt within four years (Owens, Horrocks, & House, 2002). Suicidal individuals may be at high risk for terminating their life if they have a lethal means in which to act, such as a firearm in the home (Brent & Bridge, 2003). Withdrawal from social relationships, feeling as though one is a burden to others, and engaging in reckless and risk-taking behaviors may be precursors to suicidal behavior (Berman, 2009). A sense of entrapment or feeling unable to escape one’s miserable feelings or external circumstances (e.g., an abusive relationship with no perceived way out) predicts suicidal behavior (O’Connor, Smyth, Ferguson, Ryan, & Williams, 2013). Tragically, reports of suicides among adolescents following instances of cyberbullying have emerged in recent years. In one widely-publicized case a few years ago, Phoebe Prince, a 15-year-old Massachusetts high school student, committed suicide following incessant harassment and taunting from her classmates via texting and Facebook (McCabe, 2010). Suicides can have a contagious effect on people. For example, another’s suicide, especially that of a family member, heightens one’s risk of suicide (Agerbo, Nordentoft, & Mortensen, 2002). Additionally, widely-publicized suicides tend to trigger copycat suicides in some individuals. One study examining suicide statistics in the United States from 1947–1967 found that the rates of suicide skyrocketed for the first month after a suicide story was printed on the front page of the New York Times (Phillips, 1974). Austrian researchers found a significant increase in the number of suicides by firearms in the three weeks following extensive reports in Austria’s largest newspaper of a celebrity suicide by gun (Etzersdorfer, Voracek, & Sonneck, 2004). A review of 42 studies concluded that media coverage of celebrity suicides is more than 14 times more likely to trigger copycat suicides than is coverage of non-celebrity suicides (Stack, 2000). This review also demonstrated that the medium of coverage is important: televised stories are considerably less likely to prompt a surge in suicides than are newspaper stories. Research suggests that a trend appears to be emerging whereby people use online social media to leave suicide notes, although it is not clear to what extent suicide notes on such media might induce copycat suicides (Ruder, Hatch, Ampanozi, Thali, & Fischer, 2011). Nevertheless, it is reasonable to conjecture that suicide notes left by individuals on social media may influence the decisions of other vulnerable people who encounter them (Luxton, June, & Fairall, 2012). One possible contributing factor in suicide is brain chemistry. Contemporary neurological research shows that disturbances in the functioning of serotonin are linked to suicidal behavior (Pompili et al., 2010). Low levels of serotonin predict future suicide attempts and suicide completions, and low levels have been observed post-mortem among suicide victims (Mann, 2003). Serotonin dysfunction, as noted earlier, is also known to play an important role in depression; low levels of serotonin have also been linked to aggression and impulsivity (Stanley et al., 2000). The combination of these three characteristics constitutes a potential formula for suicide—especially violent suicide. A classic study conducted during the 1970s found that patients with major depressive disorder who had very low levels of serotonin attempted suicide more frequently and more violently than did patients with higher levels (Asberg, Thorén, Träskman, Bertilsson, & Ringberger, 1976; Mann, 2003). Suicidal thoughts, plans, and even off-hand remarks (“I might kill myself this afternoon”) should always be taken extremely seriously. People who contemplate terminating their life need immediate help. Below are links to two excellent websites that contain resources (including hotlines) for people who are struggling with suicidal ideation, have loved ones who may be suicidal, or who have lost loved ones to suicide: http://www.afsp.org and http://suicidology.org. 15.8 Schizophrenia Learning Objectives By the end of this section, you will be able to: Recognize the essential nature of schizophrenia, avoiding the misconception that it involves a split personality Categorize and describe the major symptoms of schizophrenia Understand the interplay between genetic, biological, and environmental factors that are associated with the development of schizophrenia Discuss the importance of research examining prodromal symptoms of schizophrenia Schizophrenia is a devastating psychological disorder that is characterized by major disturbances in thought, perception, emotion, and behavior. About 1% of the population experiences schizophrenia in their lifetime, and usually the disorder is first diagnosed during early adulthood (early to mid-20s). Most people with schizophrenia experience significant difficulties in many day-to-day activities, such as holding a job, paying bills, caring for oneself (grooming and hygiene), and maintaining relationships with others. Frequent hospitalizations are more often the rule rather than the exception with schizophrenia. Even when they receive the best treatments available, many with schizophrenia will continue to experience serious social and occupational impairment throughout their lives. What is schizophrenia? First, schizophrenia is not a condition involving a split personality; that is, schizophrenia is not the same thing as dissociative identity disorder (better known as multiple personality disorder). These disorders are sometimes confused because the word schizophrenia first coined by the Swiss psychiatrist Eugen Bleuler in 1911, derives from Greek words that refer to a “splitting” (schizo) of psychic functions (phrene) (Green, 2001). Schizophrenia is considered a psychotic disorder, or one in which the person’s thoughts, perceptions, and behaviors are impaired to the point where she is not able to function normally in life. In informal terms, one who suffers from a psychotic disorder (that is, has a psychosis) is disconnected from the world in which most of us live. Symptoms of Schizophrenia The main symptoms of schizophrenia include hallucinations, delusions, disorganized thinking, disorganized or abnormal motor behavior, and negative symptoms (APA, 2013). A hallucination is a perceptual experience that occurs in the absence of external stimulation. Auditory hallucinations (hearing voices) occur in roughly two-thirds of patients with schizophrenia and are by far the most common form of hallucination (Andreasen, 1987). The voices may be familiar or unfamiliar, they may have a conversation or argue, or the voices may provide a running commentary on the person’s behavior (Tsuang, Farone, & Green, 1999). Less common are visual hallucinations (seeing things that are not there) and olfactory hallucinations (smelling odors that are not actually present). Delusions are beliefs that are contrary to reality and are firmly held even in the face of contradictory evidence. Many of us hold beliefs that some would consider odd, but a delusion is easily identified because it is clearly absurd. A person with schizophrenia may believe that his mother is plotting with the FBI to poison his coffee, or that his neighbor is an enemy spy who wants to kill him. These kinds of delusions are known as paranoid delusions , which involve the (false) belief that other people or agencies are plotting to harm the person. People with schizophrenia also may hold grandiose delusions , beliefs that one holds special power, unique knowledge, or is extremely important. For example, the person who claims to be Jesus Christ, or who claims to have knowledge going back 5,000 years, or who claims to be a great philosopher is experiencing grandiose delusions. Other delusions include the belief that one’s thoughts are being removed (thought withdrawal) or thoughts have been placed inside one’s head (thought insertion). Another type of delusion is somatic delusion , which is the belief that something highly abnormal is happening to one’s body (e.g., that one’s kidneys are being eaten by cockroaches). Disorganized thinking refers to disjointed and incoherent thought processes—usually detected by what a person says. The person might ramble, exhibit loose associations (jump from topic to topic), or talk in a way that is so disorganized and incomprehensible that it seems as though the person is randomly combining words. Disorganized thinking is also exhibited by blatantly illogical remarks (e.g., “Fenway Park is in Boston. I live in Boston. Therefore, I live at Fenway Park.”) and by tangentiality: responding to others’ statements or questions by remarks that are either barely related or unrelated to what was said or asked. For example, if a person diagnosed with schizophrenia is asked if she is interested in receiving special job training, she might state that she once rode on a train somewhere. To a person with schizophrenia, the tangential (slightly related) connection between job training and riding a train are sufficient enough to cause such a response. Disorganized or abnormal motor behavior refers to unusual behaviors and movements: becoming unusually active, exhibiting silly child-like behaviors (giggling and self-absorbed smiling), engaging in repeated and purposeless movements, or displaying odd facial expressions and gestures. In some cases, the person will exhibit catatonic behaviors , which show decreased reactivity to the environment, such as posturing, in which the person maintains a rigid and bizarre posture for long periods of time, or catatonic stupor, a complete lack of movement and verbal behavior. Negative symptoms are those that reflect noticeable decreases and absences in certain behaviors, emotions, or drives (Green, 2001). A person who exhibits diminished emotional expression shows no emotion in his facial expressions, speech, or movements, even when such expressions are normal or expected. Avolition is characterized by a lack of motivation to engage in self-initiated and meaningful activity, including the most basic of tasks, such as bathing and grooming. Alogia refers to reduced speech output; in simple terms, patients do not say much. Another negative symptom is asociality, or social withdrawal and lack of interest in engaging in social interactions with others. A final negative symptom, anhedonia, refers to an inability to experience pleasure. One who exhibits anhedonia expresses little interest in what most people consider to be pleasurable activities, such as hobbies, recreation, or sexual activity. Link to Learning Watch this video and try to identify which classic symptoms of schizophrenia are shown. Causes of Schizophrenia There is considerable evidence suggesting that schizophrenia has a genetic basis. The risk of developing schizophrenia is nearly 6 times greater if one has a parent with schizophrenia than if one does not (Goldstein, Buka, Seidman, & Tsuang, 2010). Additionally, one’s risk of developing schizophrenia increases as genetic relatedness to family members diagnosed with schizophrenia increases (Gottesman, 2001). Genes When considering the role of genetics in schizophrenia, as in any disorder, conclusions based on family and twin studies are subject to criticism. This is because family members who are closely related (such as siblings) are more likely to share similar environments than are family members who are less closely related (such as cousins); further, identical twins may be more likely to be treated similarly by others than might fraternal twins. Thus, family and twin studies cannot completely rule out the possible effects of shared environments and experiences. Such problems can be corrected by using adoption studies, in which children are separated from their parents at an early age. One of the first adoption studies of schizophrenia conducted by Heston (1966) followed 97 adoptees, including 47 who were born to mothers with schizophrenia, over a 36-year period. Five of the 47 adoptees (11%) whose mothers had schizophrenia were later diagnosed with schizophrenia, compared to none of the 50 control adoptees. Other adoption studies have consistently reported that for adoptees who are later diagnosed with schizophrenia, their biological relatives have a higher risk of schizophrenia than do adoptive relatives (Shih, Belmonte, & Zandi, 2004). Although adoption studies have supported the hypothesis that genetic factors contribute to schizophrenia, they have also demonstrated that the disorder most likely arises from a combination of genetic and environmental factors, rather than just genes themselves. For example, investigators in one study examined the rates of schizophrenia among 303 adoptees (Tienari et al., 2004). A total of 145 of the adoptees had biological mothers with schizophrenia; these adoptees constituted the high genetic risk group. The other 158 adoptees had mothers with no psychiatric history; these adoptees composed the low genetic risk group. The researchers managed to determine whether the adoptees’ families were either healthy or disturbed. For example, the adoptees were considered to be raised in a disturbed family environment if the family exhibited a lot of criticism, conflict, and a lack of problem-solving skills. The findings revealed that adoptees whose mothers had schizophrenia (high genetic risk) and who had been raised in a disturbed family environment were much more likely to develop schizophrenia or another psychotic disorder (36.8%) than were adoptees whose biological mothers had schizophrenia but who had been raised in a healthy environment (5.8%), or than adoptees with a low genetic risk who were raised in either a disturbed (5.3%) or healthy (4.8%) environment. Because the adoptees who were at high genetic risk were likely to develop schizophrenia only if they were raised in a disturbed home environment, this study supports a diathesis-stress interpretation of schizophrenia—both genetic vulnerability and environmental stress are necessary for schizophrenia to develop, genes alone do not show the complete picture. Neurotransmitters If we accept that schizophrenia is at least partly genetic in origin, as it seems to be, it makes sense that the next step should be to identify biological abnormalities commonly found in people with the disorder. Perhaps not surprisingly, a number of neurobiological factors have indeed been found to be related to schizophrenia. One such factor that has received considerable attention for many years is the neurotransmitter dopamine. Interest in the role of dopamine in schizophrenia was stimulated by two sets of findings: drugs that increase dopamine levels can produce schizophrenia-like symptoms, and medications that block dopamine activity reduce the symptoms (Howes & Kapur, 2009). The dopamine hypothesis of schizophrenia proposed that an overabundance of dopamine or too many dopamine receptors are responsible for the onset and maintenance of schizophrenia (Snyder, 1976). More recent work in this area suggests that abnormalities in dopamine vary by brain region and thus contribute to symptoms in unique ways. In general, this research has suggested that an overabundance of dopamine in the limbic system may be responsible for some symptoms, such as hallucinations and delusions, whereas low levels of dopamine in the prefrontal cortex might be responsible primarily for the negative symptoms (avolition, alogia, asociality, and anhedonia) (Davis, Kahn, Ko, & Davidson, 1991). In recent years, serotonin has received attention, and newer antipsychotic medications used to treat the disorder work by blocking serotonin receptors (Baumeister & Hawkins, 2004). Brain Anatomy Brain imaging studies reveal that people with schizophrenia have enlarged ventricles , the cavities within the brain that contain cerebral spinal fluid (Green, 2001). This finding is important because larger than normal ventricles suggests that various brain regions are reduced in size, thus implying that schizophrenia is associated with a loss of brain tissue. In addition, many people with schizophrenia display a reduction in gray matter (cell bodies of neurons) in the frontal lobes (Lawrie & Abukmeil, 1998), and many show less frontal lobe activity when performing cognitive tasks (Buchsbaum et al., 1990). The frontal lobes are important in a variety of complex cognitive functions, such as planning and executing behavior, attention, speech, movement, and problem solving. Hence, abnormalities in this region provide merit in explaining why people with schizophrenia experience deficits in these of areas. Events During Pregnancy Why do people with schizophrenia have these brain abnormalities? A number of environmental factors that could impact normal brain development might be at fault. High rates of obstetric complications in the births of children who later developed schizophrenia have been reported (Cannon, Jones, & Murray, 2002). In addition, people are at an increased risk for developing schizophrenia if their mother was exposed to influenza during the first trimester of pregnancy (Brown et al., 2004). Research has also suggested that a mother’s emotional stress during pregnancy may increase the risk of schizophrenia in offspring. One study reported that the risk of schizophrenia is elevated substantially in offspring whose mothers experienced the death of a relative during the first trimester of pregnancy (Khashan et al., 2008). Marijuana Another variable that is linked to schizophrenia is marijuana use. Although a number of reports have shown that individuals with schizophrenia are more likely to use marijuana than are individuals without schizophrenia (Thornicroft, 1990), such investigations cannot determine if marijuana use leads to schizophrenia, or vice versa. However, a number of longitudinal studies have suggested that marijuana use is, in fact, a risk factor for schizophrenia. A classic investigation of over 45,000 Swedish conscripts who were followed up after 15 years found that those individuals who had reported using marijuana at least once by the time of conscription were more than 2 times as likely to develop schizophrenia during the ensuing 15 years than were those who reported never using marijuana; those who had indicated using marijuana 50 or more times were 6 times as likely to develop schizophrenia (Andréasson, Allbeck, Engström, & Rydberg, 1987). More recently, a review of 35 longitudinal studies found a substantially increased risk of schizophrenia and other psychotic disorders in people who had used marijuana, with the greatest risk in the most frequent users (Moore et al., 2007). Other work has found that marijuana use is associated with an onset of psychotic disorders at an earlier age (Large, Sharma, Compton, Slade, & Nielssen, 2011). Overall, the available evidence seems to indicate that marijuana use plays a causal role in the development of schizophrenia, although it is important to point out that marijuana use is not an essential or sufficient risk factor as not all people with schizophrenia have used marijuana and the majority of marijuana users do not develop schizophrenia (Casadio, Fernandes, Murray, & Di Forti, 2011). One plausible interpretation of the data is that early marijuana use may disrupt normal brain development during important early maturation periods in adolescence (Trezza, Cuomo, & Vanderschuren, 2008). Thus, early marijuana use may set the stage for the development of schizophrenia and other psychotic disorders, especially among individuals with an established vulnerability (Casadio et al., 2011). Schizophrenia: Early Warning Signs Early detection and treatment of conditions such as heart disease and cancer have improved survival rates and quality of life for people who suffer from these conditions. A new approach involves identifying people who show minor symptoms of psychosis, such as unusual thought content, paranoia, odd communication, delusions, problems at school or work, and a decline in social functioning—which are coined prodromal symptoms —and following these individuals over time to determine which of them develop a psychotic disorder and which factors best predict such a disorder. A number of factors have been identified that predict a greater likelihood that prodromal individuals will develop a psychotic disorder: genetic risk (a family history of psychosis), recent deterioration in functioning, high levels of unusual thought content, high levels of suspicion or paranoia, poor social functioning, and a history of substance abuse (Fusar-Poli et al., 2013). Further research will enable a more accurate prediction of those at greatest risk for developing schizophrenia, and thus to whom early intervention efforts should be directed. 15.9 Dissociative Disorders Learning Objectives By the end of this section, you will be able to: Describe the essential nature of dissociative disorders Identify and differentiate the symptoms of dissociative amnesia, depersonalization/ derealization disorder, and dissociative identity disorder Discuss the potential role of both social and psychological factors in dissociative identity disorder Dissociative disorders are characterized by an individual becoming split off, or dissociated, from her core sense of self. Memory and identity become disturbed; these disturbances have a psychological rather than physical cause. Dissociative disorders listed in the DSM-5 include dissociative amnesia, depersonalization/derealization disorder, and dissociative identity disorder. Dissociative Amnesia Amnesia refers to the partial or total forgetting of some experience or event. An individual with dissociative amnesia is unable to recall important personal information, usually following an extremely stressful or traumatic experience such as combat, natural disasters, or being the victim of violence. The memory impairments are not caused by ordinary forgetting. Some individuals with dissociative amnesia will also experience dissociative fugue (from the word “to flee” in French), whereby they suddenly wander away from their home, experience confusion about their identity, and sometimes even adopt a new identity (Cardeña & Gleaves, 2006). Most fugue episodes last only a few hours or days, but some can last longer. One study of residents in communities in upstate New York reported that about 1.8% experienced dissociative amnesia in the previous year (Johnson, Cohen, Kasen, & Brook, 2006). Some have questioned the validity of dissociative amnesia (Pope, Hudson, Bodkin, & Oliva, 1998); it has even been characterized as a “piece of psychiatric folklore devoid of convincing empirical support” (McNally, 2003, p. 275). Notably, scientific publications regarding dissociative amnesia rose during the 1980s and reached a peak in the mid-1990s, followed by an equally sharp decline by 2003; in fact, only 13 cases of individuals with dissociative amnesia worldwide could be found in the literature that same year (Pope, Barry, Bodkin, & Hudson, 2006). Further, no description of individuals showing dissociative amnesia following a trauma exists in any fictional or nonfictional work prior to 1800 (Pope, Poliakoff, Parker, Boynes, & Hudson, 2006). However, a study of 82 individuals who enrolled for treatment at a psychiatric outpatient hospital found that nearly 10% met the criteria for dissociative amnesia, perhaps suggesting that the condition is underdiagnosed, especially in psychiatric populations (Foote, Smolin, Kaplan, Legatt, & Lipschitz, 2006). Depersonalization/Derealization Disorder Depersonalization/derealization disorder is characterized by recurring episodes of depersonalization, derealization, or both. Depersonalization is defined as feelings of “unreality or detachment from, or unfamiliarity with, one’s whole self or from aspects of the self” (APA, 2013, p. 302). Individuals who experience depersonalization might believe their thoughts and feelings are not their own; they may feel robotic as though they lack control over their movements and speech; they may experience a distorted sense of time and, in extreme cases, they may sense an “out-of-body” experience in which they see themselves from the vantage point of another person. Derealization is conceptualized as a sense of “unreality or detachment from, or unfamiliarity with, the world, be it individuals, inanimate objects, or all surroundings” (APA, 2013, p. 303). A person who experiences derealization might feel as though he is in a fog or a dream, or that the surrounding world is somehow artificial and unreal. Individuals with depersonalization/derealization disorder often have difficulty describing their symptoms and may think they are going crazy (APA, 2013). Dissociative Identity Disorder By far, the most well-known dissociative disorder is dissociative identity disorder (formerly called multiple personality disorder). People with dissociative identity disorder exhibit two or more separate personalities or identities, each well-defined and distinct from one another. They also experience memory gaps for the time during which another identity is in charge (e.g., one might find unfamiliar items in her shopping bags or among her possessions), and in some cases may report hearing voices, such as a child’s voice or the sound of somebody crying (APA, 2013). The study of upstate New York residents mentioned above (Johnson et al., 2006) reported that 1.5% of their sample experienced symptoms consistent with dissociative identity disorder in the previous year. Dissociative identity disorder (DID) is highly controversial. Some believe that people fake symptoms to avoid the consequences of illegal actions (e.g., “I am not responsible for shoplifting because it was my other personality”). In fact, it has been demonstrated that people are generally skilled at adopting the role of a person with different personalities when they believe it might be advantageous to do so. As an example, Kenneth Bianchi was an infamous serial killer who, along with his cousin, murdered over a dozen females around Los Angeles in the late 1970s. Eventually, he and his cousin were apprehended. At Bianchi’s trial, he pled not guilty by reason of insanity, presenting himself as though he had DID and claiming that a different personality (“Steve Walker”) committed the murders. When these claims were scrutinized, he admitted faking the symptoms and was found guilty (Schwartz, 1981). A second reason DID is controversial is because rates of the disorder suddenly skyrocketed in the 1980s. More cases of DID were identified during the five years prior to 1986 than in the preceding two centuries (Putnam, Guroff, Silberman, Barban, & Post, 1986). Although this increase may be due to the development of more sophisticated diagnostic techniques, it is also possible that the popularization of DID—helped in part by Sybil , a popular 1970s book (and later film) about a woman with 16 different personalities—may have prompted clinicians to overdiagnose the disorder (Piper & Merskey, 2004). Casting further scrutiny on the existence of multiple personalities or identities is the recent suggestion that the story of Sybil was largely fabricated, and the idea for the book might have been exaggerated (Nathan, 2011). Despite its controversial nature, DID is clearly a legitimate and serious disorder, and although some people may fake symptoms, others suffer their entire lives with it. People with this disorder tend to report a history of childhood trauma, some cases having been corroborated through medical or legal records (Cardeña & Gleaves, 2006). Research by Ross et al. (1990) suggests that in one study about 95% of people with DID were physically and/or sexually abused as children. Of course, not all reports of childhood abuse can be expected to be valid or accurate. However, there is strong evidence that traumatic experiences can cause people to experience states of dissociation, suggesting that dissociative states—including the adoption of multiple personalities—may serve as a psychologically important coping mechanism for threat and danger (Dalenberg et al., 2012).
anatomy_and_physiology
Chapter Objectives After studying this chapter, you will be able to: Describe the components of the autonomic nervous system Differentiate between the structures of the sympathetic and parasympathetic divisions in the autonomic nervous system Name the components of a visceral reflex specific to the autonomic division to which it belongs Predict the response of a target effector to autonomic input on the basis of the released signaling molecule Describe how the central nervous system coordinates and contributes to autonomic functions Introduction The autonomic nervous system is often associated with the “fight-or-flight response,” which refers to the preparation of the body to either run away from a threat or to stand and fight in the face of that threat. To suggest what this means, consider the (very unlikely) situation of seeing a lioness hunting out on the savannah. Though this is not a common threat that humans deal with in the modern world, it represents the type of environment in which the human species thrived and adapted. The spread of humans around the world to the present state of the modern age occurred much more quickly than any species would adapt to environmental pressures such as predators. However, the reactions modern humans have in the modern world are based on these prehistoric situations. If your boss is walking down the hallway on Friday afternoon looking for “volunteers” to come in on the weekend, your response is the same as the prehistoric human seeing the lioness running across the savannah: fight or flight. Most likely, your response to your boss—not to mention the lioness—would be flight. Run away! The autonomic system is responsible for the physiological response to make that possible, and hopefully successful. Adrenaline starts to flood your circulatory system. Your heart rate increases. Sweat glands become active. The bronchi of the lungs dilate to allow more air exchange. Pupils dilate to increase visual information. Blood pressure increases in general, and blood vessels dilate in skeletal muscles. Time to run. Similar physiological responses would occur in preparation for fighting off the threat. This response should sound a bit familiar. The autonomic nervous system is tied into emotional responses as well, and the fight-or-flight response probably sounds like a panic attack. In the modern world, these sorts of reactions are associated with anxiety as much as with response to a threat. It is engrained in the nervous system to respond like this. In fact, the adaptations of the autonomic nervous system probably predate the human species and are likely to be common to all mammals, and perhaps shared by many animals. That lioness might herself be threatened in some other situation. However, the autonomic nervous system is not just about responding to threats. Besides the fight-or-flight response, there are the responses referred to as “rest and digest.” If that lioness is successful in her hunting, then she is going to rest from the exertion. Her heart rate will slow. Breathing will return to normal. The digestive system has a big job to do. Much of the function of the autonomic system is based on the connections within an autonomic, or visceral, reflex.
[ { "answer": { "ans_choice": 3, "ans_text": "increased stomach motility" }, "bloom": "1", "hl_context": "In addition to its association with the fight-or-flight response and rest-and-digest functions , the autonomic system is responsible for certain everyday functions . For example , it comes into play when homeostatic mechanisms dynamically change , such as the physiological changes that accompany exercise . <hl> Getting on the treadmill and putting in a good workout will cause the heart rate to increase , breathing to be stronger and deeper , sweat glands to activate , and the digestive system to suspend activity . <hl> <hl> These are the same physiological changes associated with the fight-or-flight response , but there is nothing chasing you on that treadmill . <hl> Introduction The autonomic nervous system is often associated with the “ fight-or-flight response , ” which refers to the preparation of the body to either run away from a threat or to stand and fight in the face of that threat . To suggest what this means , consider the ( very unlikely ) situation of seeing a lioness hunting out on the savannah . Though this is not a common threat that humans deal with in the modern world , it represents the type of environment in which the human species thrived and adapted . The spread of humans around the world to the present state of the modern age occurred much more quickly than any species would adapt to environmental pressures such as predators . However , the reactions modern humans have in the modern world are based on these prehistoric situations . If your boss is walking down the hallway on Friday afternoon looking for “ volunteers ” to come in on the weekend , your response is the same as the prehistoric human seeing the lioness running across the savannah : fight or flight . Most likely , your response to your boss — not to mention the lioness — would be flight . Run away ! The autonomic system is responsible for the physiological response to make that possible , and hopefully successful . Adrenaline starts to flood your circulatory system . <hl> Your heart rate increases . <hl> <hl> Sweat glands become active . <hl> The bronchi of the lungs dilate to allow more air exchange . <hl> Pupils dilate to increase visual information . <hl> Blood pressure increases in general , and blood vessels dilate in skeletal muscles . Time to run . Similar physiological responses would occur in preparation for fighting off the threat . This response should sound a bit familiar . <hl> The autonomic nervous system is tied into emotional responses as well , and the fight-or-flight response probably sounds like a panic attack . <hl> In the modern world , these sorts of reactions are associated with anxiety as much as with response to a threat . It is engrained in the nervous system to respond like this . In fact , the adaptations of the autonomic nervous system probably predate the human species and are likely to be common to all mammals , and perhaps shared by many animals . That lioness might herself be threatened in some other situation . However , the autonomic nervous system is not just about responding to threats . Besides the fight-or-flight response , there are the responses referred to as “ rest and digest . ” If that lioness is successful in her hunting , then she is going to rest from the exertion . Her heart rate will slow . Breathing will return to normal . The digestive system has a big job to do . Much of the function of the autonomic system is based on the connections within an autonomic , or visceral , reflex .", "hl_sentences": "Getting on the treadmill and putting in a good workout will cause the heart rate to increase , breathing to be stronger and deeper , sweat glands to activate , and the digestive system to suspend activity . These are the same physiological changes associated with the fight-or-flight response , but there is nothing chasing you on that treadmill . Your heart rate increases . Sweat glands become active . Pupils dilate to increase visual information . The autonomic nervous system is tied into emotional responses as well , and the fight-or-flight response probably sounds like a panic attack .", "question": { "cloze_format": "___ is a physiological changes that would not be considered part of the sympathetic fight-or-flight response.", "normal_format": "Which of these physiological changes would not be considered part of the sympathetic fight-or-flight response?", "question_choices": [ "increased heart rate", "increased sweating", "dilated pupils", "increased stomach motility" ], "question_id": "fs-id1643874", "question_text": "Which of these physiological changes would not be considered part of the sympathetic fight-or-flight response?" }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 0, "ans_text": "preganglionic parasympathetic" }, "bloom": null, "hl_context": "The connections , or “ circuits , ” of the parasympathetic division are similar to the general layout of the sympathetic division with a few specific differences ( Figure 15.4 ) . The preganglionic fibers from the cranial region travel in cranial nerves , whereas preganglionic fibers from the sacral region travel in spinal nerves . The targets of these fibers are terminal ganglia , which are located near — or even within — the target effector . These ganglia are often referred to as intramural ganglia when they are found within the walls of the target organ . The postganglionic fiber projects from the terminal ganglia a short distance to the target effector , or to the specific target tissue within the organ . <hl> Comparing the relative lengths of axons in the parasympathetic system , the preganglionic fibers are long and the postganglionic fibers are short because the ganglia are close to — and sometimes within — the target effectors . <hl>", "hl_sentences": "Comparing the relative lengths of axons in the parasympathetic system , the preganglionic fibers are long and the postganglionic fibers are short because the ganglia are close to — and sometimes within — the target effectors .", "question": { "cloze_format": "The type of fiber that could be considered the longest is ___.", "normal_format": "Which type of fiber could be considered the longest?", "question_choices": [ "preganglionic parasympathetic", "preganglionic sympathetic", "postganglionic parasympathetic", "postganglionic sympathetic" ], "question_id": "fs-id2181456", "question_text": "Which type of fiber could be considered the longest?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 0, "ans_text": "intermural ganglion" }, "bloom": "1", "hl_context": "The projections of the sympathetic division of the autonomic nervous system diverge widely , resulting in a broad influence of the system throughout the body . As a response to a threat , the sympathetic system would increase heart rate and breathing rate and cause blood flow to the skeletal muscle to increase and blood flow to the digestive system to decrease . Sweat gland secretion should also increase as part of an integrated response . All of those physiological changes are going to be required to occur together to run away from the hunting lioness , or the modern equivalent . This divergence is seen in the branching patterns of preganglionic sympathetic neurons — a single preganglionic sympathetic neuron may have 10 – 20 targets . <hl> An axon that leaves a central neuron of the lateral horn in the thoracolumbar spinal cord will pass through the white ramus communicans and enter the sympathetic chain , where it will branch toward a variety of targets . <hl> <hl> At the level of the spinal cord at which the preganglionic sympathetic fiber exits the spinal cord , a branch will synapse on a neuron in the adjacent chain ganglion . <hl> Some branches will extend up or down to a different level of the chain ganglia . <hl> Other branches will pass through the chain ganglia and project through one of the splanchnic nerves to a collateral ganglion . <hl> Finally , some branches may project through the splanchnic nerves to the adrenal medulla . All of these branches mean that one preganglionic neuron can influence different regions of the sympathetic system very broadly , by acting on widely distributed organs . <hl> One type of preganglionic sympathetic fiber does not terminate in a ganglion . <hl> <hl> These are the axons from central sympathetic neurons that project to the adrenal medulla , the interior portion of the adrenal gland . <hl> These axons are still referred to as preganglionic fibers , but the target is not a ganglion . The adrenal medulla releases signaling molecules into the bloodstream , rather than using axons to communicate with target structures . The cells in the adrenal medulla that are contacted by the preganglionic fibers are called chromaffin cells . These cells are neurosecretory cells that develop from the neural crest along with the sympathetic ganglia , reinforcing the idea that the gland is , functionally , a sympathetic ganglion .", "hl_sentences": "An axon that leaves a central neuron of the lateral horn in the thoracolumbar spinal cord will pass through the white ramus communicans and enter the sympathetic chain , where it will branch toward a variety of targets . At the level of the spinal cord at which the preganglionic sympathetic fiber exits the spinal cord , a branch will synapse on a neuron in the adjacent chain ganglion . Other branches will pass through the chain ganglia and project through one of the splanchnic nerves to a collateral ganglion . One type of preganglionic sympathetic fiber does not terminate in a ganglion . These are the axons from central sympathetic neurons that project to the adrenal medulla , the interior portion of the adrenal gland .", "question": { "cloze_format": "___ is not a target of a sympathetic preganglionic fiber.", "normal_format": "Which of the following is not a target of a sympathetic preganglionic fiber?", "question_choices": [ "intermural ganglion", "collateral ganglion", "adrenal gland", "chain ganglion" ], "question_id": "fs-id2766993", "question_text": "Which of the following is not a target of a sympathetic preganglionic fiber?" }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 2, "ans_text": "baroreception" }, "bloom": "1", "hl_context": "The afferent branch of a reflex arc does differ between somatic and visceral reflexes in some instances . <hl> Many of the inputs to visceral reflexes are from special or somatic senses , but particular senses are associated with the viscera that are not part of the conscious perception of the environment through the somatic nervous system . <hl> <hl> For example , there is a specific type of mechanoreceptor , called a baroreceptor , in the walls of the aorta and carotid sinuses that senses the stretch of those organs when blood volume or pressure increases . <hl> You do not have a conscious perception of having high blood pressure , but that is an important afferent branch of the cardiovascular and , particularly , vasomotor reflexes . The sensory neuron is essentially the same as any other general sensory neuron . The baroreceptor apparatus is part of the ending of a unipolar neuron that has a cell body in a sensory ganglion . The baroreceptors from the carotid arteries have axons in the glossopharyngeal nerve , and those from the aorta have axons in the vagus nerve .", "hl_sentences": "Many of the inputs to visceral reflexes are from special or somatic senses , but particular senses are associated with the viscera that are not part of the conscious perception of the environment through the somatic nervous system . For example , there is a specific type of mechanoreceptor , called a baroreceptor , in the walls of the aorta and carotid sinuses that senses the stretch of those organs when blood volume or pressure increases .", "question": { "cloze_format": "___ represents a sensory input that is not part of both the somatic and autonomic systems.", "normal_format": "Which of the following represents a sensory input that is not part of both the somatic and autonomic systems?", "question_choices": [ "vision", "taste", "baroreception", "proprioception" ], "question_id": "fs-id2871108", "question_text": "Which of the following represents a sensory input that is not part of both the somatic and autonomic systems?" }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 3, "ans_text": "short reflex" }, "bloom": "1", "hl_context": "Somatic reflexes involve sensory neurons that connect sensory receptors to the CNS and motor neurons that project back out to the skeletal muscles . Visceral reflexes that involve the thoracolumbar or craniosacral systems share similar connections . <hl> However , there are reflexes that do not need to involve any CNS components . <hl> A long reflex has afferent branches that enter the spinal cord or brain and involve the efferent branches , as previously explained . <hl> A short reflex is completely peripheral and only involves the local integration of sensory input with motor output ( Figure 15.8 ) . <hl>", "hl_sentences": "However , there are reflexes that do not need to involve any CNS components . A short reflex is completely peripheral and only involves the local integration of sensory input with motor output ( Figure 15.8 ) .", "question": { "cloze_format": "A ___ is the term for a reflex that does not include a CNS component.", "normal_format": "What is the term for a reflex that does not include a CNS component?", "question_choices": [ "long reflex", "visceral reflex", "somatic reflex", "short reflex" ], "question_id": "fs-id2229746", "question_text": "What is the term for a reflex that does not include a CNS component?" }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 1, "ans_text": "acetylcholine" }, "bloom": null, "hl_context": "Another example is in the control of pupillary size ( Figure 15.9 ) . The afferent branch responds to light hitting the retina . Photoreceptors are activated , and the signal is transferred to the retinal ganglion cells that send an action potential along the optic nerve into the diencephalon . If light levels are low , the sympathetic system sends a signal out through the upper thoracic spinal cord to the superior cervical ganglion of the sympathetic chain . The postganglionic fiber then projects to the iris , where it releases norepinephrine onto the radial fibers of the iris ( a smooth muscle ) . When those fibers contract , the pupil dilates — increasing the amount of light hitting the retina . If light levels are too high , the parasympathetic system sends a signal out from the Edinger – Westphal nucleus through the oculomotor nerve . This fiber synapses in the ciliary ganglion in the posterior orbit . <hl> The postganglionic fiber then projects to the iris , where it releases ACh onto the circular fibers of the iris — another smooth muscle . <hl> <hl> When those fibers contract , the pupil constricts to limit the amount of light hitting the retina . <hl> Where an autonomic neuron connects with a target , there is a synapse . The electrical signal of the action potential causes the release of a signaling molecule , which will bind to receptor proteins on the target cell . <hl> Synapses of the autonomic system are classified as either cholinergic , meaning that acetylcholine ( ACh ) is released , or adrenergic , meaning that norepinephrine is released . <hl> The terms cholinergic and adrenergic refer not only to the signaling molecule that is released but also to the class of receptors that each binds .", "hl_sentences": "The postganglionic fiber then projects to the iris , where it releases ACh onto the circular fibers of the iris — another smooth muscle . When those fibers contract , the pupil constricts to limit the amount of light hitting the retina . Synapses of the autonomic system are classified as either cholinergic , meaning that acetylcholine ( ACh ) is released , or adrenergic , meaning that norepinephrine is released .", "question": { "cloze_format": "The neurotransmitter ___ will result in constriction of the pupil.", "normal_format": "What neurotransmitter will result in constriction of the pupil?", "question_choices": [ "norepinephrine", "acetylcholine", "epinephrine", "serotonin" ], "question_id": "fs-id1602322", "question_text": "What neurotransmitter will result in constriction of the pupil?" }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 0, "ans_text": "adrenal medulla" }, "bloom": null, "hl_context": "The adrenergic system also has two types of receptors , named the alpha ( α ) - adrenergic receptor and beta ( β ) - adrenergic receptor . Unlike cholinergic receptors , these receptor types are not classified by which drugs can bind to them . All of them are G protein – coupled receptors . There are two types of α-adrenergic receptors , termed α 1 , and α 2 , and there are three types of β-adrenergic receptors , termed β 1 , β 2 and β 3 . An additional aspect of the adrenergic system is that there is a second signaling molecule called epinephrine . The chemical difference between norepinephrine and epinephrine is the addition of a methyl group ( CH 3 ) in epinephrine . The prefix “ nor - ” actually refers to this chemical difference , in which a methyl group is missing . <hl> The term adrenergic should remind you of the word adrenaline , which is associated with the fight-or-flight response described at the beginning of the chapter . <hl> Adrenaline and epinephrine are two names for the same molecule . <hl> The adrenal gland ( in Latin , ad - = “ on top of ” ; renal = “ kidney ” ) secretes adrenaline . <hl> The ending “ - ine ” refers to the chemical being derived , or extracted , from the adrenal gland . A similar construction from Greek instead of Latin results in the word epinephrine ( epi - = “ above ” ; nephr - = “ kidney ” ) . In scientific usage , epinephrine is preferred in the United States , whereas adrenaline is preferred in Great Britain , because “ adrenalin ” was once a registered , proprietary drug name in the United States . Though the drug is no longer sold , the convention of referring to this molecule by the two different names persists . Similarly , norepinephrine and noradrenaline are two names for the same molecule . One type of preganglionic sympathetic fiber does not terminate in a ganglion . <hl> These are the axons from central sympathetic neurons that project to the adrenal medulla , the interior portion of the adrenal gland . <hl> These axons are still referred to as preganglionic fibers , but the target is not a ganglion . The adrenal medulla releases signaling molecules into the bloodstream , rather than using axons to communicate with target structures . The cells in the adrenal medulla that are contacted by the preganglionic fibers are called chromaffin cells . These cells are neurosecretory cells that develop from the neural crest along with the sympathetic ganglia , reinforcing the idea that the gland is , functionally , a sympathetic ganglion .", "hl_sentences": "The term adrenergic should remind you of the word adrenaline , which is associated with the fight-or-flight response described at the beginning of the chapter . The adrenal gland ( in Latin , ad - = “ on top of ” ; renal = “ kidney ” ) secretes adrenaline . These are the axons from central sympathetic neurons that project to the adrenal medulla , the interior portion of the adrenal gland .", "question": { "cloze_format": "A(n) ___ is a gland that produces a secretion that causes fight-or-flight responses in effectors.", "normal_format": "What gland produces a secretion that causes fight-or-flight responses in effectors?", "question_choices": [ "adrenal medulla", "salivatory gland", "reproductive gland", "thymus" ], "question_id": "fs-id2016044", "question_text": "What gland produces a secretion that causes fight-or-flight responses in effectors?" }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 2, "ans_text": "acetylcholine decreases digestion" }, "bloom": "3", "hl_context": "In a similar fashion , another aspect of the cardiovascular system is primarily under sympathetic control . Blood pressure is partially determined by the contraction of smooth muscle in the walls of blood vessels . <hl> These tissues have adrenergic receptors that respond to the release of norepinephrine from postganglionic sympathetic fibers by constricting and increasing blood pressure . <hl> <hl> The hormones released from the adrenal medulla — epinephrine and norepinephrine — will also bind to these receptors . <hl> Those hormones travel through the bloodstream where they can easily interact with the receptors in the vessel walls . The parasympathetic system has no significant input to the systemic blood vessels , so the sympathetic system determines their tone . Another example is in the control of pupillary size ( Figure 15.9 ) . The afferent branch responds to light hitting the retina . Photoreceptors are activated , and the signal is transferred to the retinal ganglion cells that send an action potential along the optic nerve into the diencephalon . If light levels are low , the sympathetic system sends a signal out through the upper thoracic spinal cord to the superior cervical ganglion of the sympathetic chain . <hl> The postganglionic fiber then projects to the iris , where it releases norepinephrine onto the radial fibers of the iris ( a smooth muscle ) . <hl> <hl> When those fibers contract , the pupil dilates — increasing the amount of light hitting the retina . <hl> If light levels are too high , the parasympathetic system sends a signal out from the Edinger – Westphal nucleus through the oculomotor nerve . This fiber synapses in the ciliary ganglion in the posterior orbit . The postganglionic fiber then projects to the iris , where it releases ACh onto the circular fibers of the iris — another smooth muscle . When those fibers contract , the pupil constricts to limit the amount of light hitting the retina .", "hl_sentences": "These tissues have adrenergic receptors that respond to the release of norepinephrine from postganglionic sympathetic fibers by constricting and increasing blood pressure . The hormones released from the adrenal medulla — epinephrine and norepinephrine — will also bind to these receptors . The postganglionic fiber then projects to the iris , where it releases norepinephrine onto the radial fibers of the iris ( a smooth muscle ) . When those fibers contract , the pupil dilates — increasing the amount of light hitting the retina .", "question": { "cloze_format": "___ is an incorrect pairing.", "normal_format": "Which of the following is an incorrect pairing?", "question_choices": [ "norepinephrine dilates the pupil", "epinephrine increases blood pressure", "acetylcholine decreases digestion", "norepinephrine increases heart rate" ], "question_id": "fs-id2473251", "question_text": "Which of the following is an incorrect pairing?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 0, "ans_text": "hypothalamus" }, "bloom": "1", "hl_context": "<hl> The hypothalamus is the control center for many homeostatic mechanisms . <hl> <hl> It regulates both autonomic function and endocrine function . <hl> The roles it plays in the pupillary reflexes demonstrates the importance of this control center . The optic nerve projects primarily to the thalamus , which is the necessary relay to the occipital cortex for conscious visual perception . Another projection of the optic nerve , however , goes to the hypothalamus .", "hl_sentences": "The hypothalamus is the control center for many homeostatic mechanisms . It regulates both autonomic function and endocrine function .", "question": { "cloze_format": "___ is the location in the forebrain that is the master control center for homeostasis through the autonomic and endocrine systems.", "normal_format": "Which of these locations in the forebrain is the master control center for homeostasis through the autonomic and endocrine systems?", "question_choices": [ "hypothalamus", "thalamus", "amygdala", "cerebral cortex" ], "question_id": "fs-id2299695", "question_text": "Which of these locations in the forebrain is the master control center for homeostasis through the autonomic and endocrine systems?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 2, "ans_text": "optic" }, "bloom": "1", "hl_context": "The hypothalamus then uses this visual system input to drive the pupillary reflexes . <hl> If the retina is activated by high levels of light , the hypothalamus stimulates the parasympathetic response . <hl> <hl> If the optic nerve message shows that low levels of light are falling on the retina , the hypothalamus activates the sympathetic response . <hl> Output from the hypothalamus follows two main tracts , the dorsal longitudinal fasciculus and the medial forebrain bundle ( Figure 15.11 ) . Along these two tracts , the hypothalamus can influence the Edinger – Westphal nucleus of the oculomotor complex or the lateral horns of the thoracic spinal cord .", "hl_sentences": "If the retina is activated by high levels of light , the hypothalamus stimulates the parasympathetic response . If the optic nerve message shows that low levels of light are falling on the retina , the hypothalamus activates the sympathetic response .", "question": { "cloze_format": "The ___ nerve projects to the hypothalamus to indicate the level of light stimuli in the retina.", "normal_format": "Which nerve projects to the hypothalamus to indicate the level of light stimuli in the retina?", "question_choices": [ "glossopharyngeal", "oculomotor", "optic", "vagus" ], "question_id": "fs-id2489364", "question_text": "Which nerve projects to the hypothalamus to indicate the level of light stimuli in the retina?" }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 1, "ans_text": "amygdala" }, "bloom": "1", "hl_context": "The amygdala is a group of nuclei in the medial region of the temporal lobe that is part of the limbic lobe ( Figure 15.12 ) . The limbic lobe includes structures that are involved in emotional responses , as well as structures that contribute to memory function . The limbic lobe has strong connections with the hypothalamus and influences the state of its activity on the basis of emotional state . For example , when you are anxious or scared , the amygdala will send signals to the hypothalamus along the medial forebrain bundle that will stimulate the sympathetic fight-or-flight response . <hl> The hypothalamus will also stimulate the release of stress hormones through its control of the endocrine system in response to amygdala input . <hl>", "hl_sentences": "The hypothalamus will also stimulate the release of stress hormones through its control of the endocrine system in response to amygdala input .", "question": { "cloze_format": "The region of the limbic lobe that is responsible for generating stress responses via the hypothalamus is the ___.", "normal_format": "What region of the limbic lobe is responsible for generating stress responses via the hypothalamus?", "question_choices": [ "hippocampus", "amygdala", "mammillary bodies", "prefrontal cortex" ], "question_id": "fs-id2139714", "question_text": "What region of the limbic lobe is responsible for generating stress responses via the hypothalamus?" }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 3, "ans_text": "cardiac accelerator nerve" }, "bloom": null, "hl_context": "The medulla contains nuclei referred to as the cardiovascular center , which controls the smooth and cardiac muscle of the cardiovascular system through autonomic connections . When the homeostasis of the cardiovascular system shifts , such as when blood pressure changes , the coordination of the autonomic system can be accomplished within this region . Furthermore , when descending inputs from the hypothalamus stimulate this area , the sympathetic system can increase activity in the cardiovascular system , such as in response to anxiety or stress . <hl> The preganglionic sympathetic fibers that are responsible for increasing heart rate are referred to as the cardiac accelerator nerves , whereas the preganglionic sympathetic fibers responsible for constricting blood vessels compose the vasomotor nerves . <hl>", "hl_sentences": "The preganglionic sympathetic fibers that are responsible for increasing heart rate are referred to as the cardiac accelerator nerves , whereas the preganglionic sympathetic fibers responsible for constricting blood vessels compose the vasomotor nerves .", "question": { "cloze_format": "___ is another name for the preganglionic sympathetic fibers that project to the heart.", "normal_format": "What is another name for the preganglionic sympathetic fibers that project to the heart?", "question_choices": [ "solitary tract", "vasomotor nerve", "vagus nerve", "cardiac accelerator nerve" ], "question_id": "fs-id2225878", "question_text": "What is another name for the preganglionic sympathetic fibers that project to the heart?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 1, "ans_text": "medial forebrain bundle" }, "bloom": "1", "hl_context": "These two tracts connect the hypothalamus with the major parasympathetic nuclei in the brain stem and the preganglionic ( central ) neurons of the thoracolumbar spinal cord . <hl> The hypothalamus also receives input from other areas of the forebrain through the medial forebrain bundle . <hl> The olfactory cortex , the septal nuclei of the basal forebrain , and the amygdala project into the hypothalamus through the medial forebrain bundle . These forebrain structures inform the hypothalamus about the state of the nervous system and can influence the regulatory processes of homeostasis . A good example of this is found in the amygdala , which is found beneath the cerebral cortex of the temporal lobe and plays a role in our ability to remember and feel emotions .", "hl_sentences": "The hypothalamus also receives input from other areas of the forebrain through the medial forebrain bundle .", "question": { "cloze_format": "The central fiber tract that connects forebrain and brain stem structures with the hypothalamus is the ___.", "normal_format": "What central fiber tract connects forebrain and brain stem structures with the hypothalamus?", "question_choices": [ "cardiac accelerator nerve", "medial forebrain bundle", "dorsal longitudinal fasciculus", "corticospinal tract" ], "question_id": "fs-id2821212", "question_text": "What central fiber tract connects forebrain and brain stem structures with the hypothalamus?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 0, "ans_text": "nicotinic" }, "bloom": "1", "hl_context": "<hl> All ganglionic neurons of the autonomic system , in both sympathetic and parasympathetic ganglia , are activated by ACh released from preganglionic fibers . <hl> <hl> The ACh receptors on these neurons are of the nicotinic type , meaning that they are ligand-gated ion channels . <hl> <hl> When the neurotransmitter released from the preganglionic fiber binds to the receptor protein , a channel opens to allow positive ions to cross the cell membrane . <hl> The result is depolarization of the ganglia . Nicotine acts as an ACh analog at these synapses , so when someone takes in the drug , it binds to these ACh receptors and activates the ganglionic neurons , causing them to depolarize . <hl> One important drug that affects the autonomic system broadly is not a pharmaceutical therapeutic agent associated with the system . <hl> <hl> This drug is nicotine . <hl> The effects of nicotine on the autonomic nervous system are important in considering the role smoking can play in health .", "hl_sentences": "All ganglionic neurons of the autonomic system , in both sympathetic and parasympathetic ganglia , are activated by ACh released from preganglionic fibers . The ACh receptors on these neurons are of the nicotinic type , meaning that they are ligand-gated ion channels . When the neurotransmitter released from the preganglionic fiber binds to the receptor protein , a channel opens to allow positive ions to cross the cell membrane . One important drug that affects the autonomic system broadly is not a pharmaceutical therapeutic agent associated with the system . This drug is nicotine .", "question": { "cloze_format": "A drug that affects both divisions of the autonomic system is going to bind to, or block, the neurotransmitter receptor ___ .", "normal_format": "A drug that affects both divisions of the autonomic system is going to bind to, or block, which type of neurotransmitter receptor?", "question_choices": [ "nicotinic", "muscarinic", "α-adrenergic", "β-adrenergic" ], "question_id": "fs-id1599720", "question_text": "A drug that affects both divisions of the autonomic system is going to bind to, or block, which type of neurotransmitter receptor?" }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 2, "ans_text": "acts like the endogenous neurotransmitter by binding to its receptor" }, "bloom": "1", "hl_context": "<hl> A common sympathomimetic drug is phenylephrine , which is a common component of decongestants . <hl> It can also be used to dilate the pupil and to raise blood pressure . <hl> Phenylephrine is known as an α 1 - adrenergic agonist , meaning that it binds to a specific adrenergic receptor , stimulating a response . <hl> In this role , phenylephrine will bind to the adrenergic receptors in bronchioles of the lungs and cause them to dilate . By opening these structures , accumulated mucus can be cleared out of the lower respiratory tract . Phenylephrine is often paired with other pharmaceuticals , such as analgesics , as in the “ sinus ” version of many over-the-counter drugs , such as Tylenol Sinus ® or Excedrin Sinus ® , or in expectorants for chest congestion such as in Robitussin CF ® . A related molecule , called pseudoephedrine , was much more commonly used in these applications than was phenylephrine , until the molecule became useful in the illicit production of amphetamines . Phenylephrine is not as effective as a drug because it can be partially broken down in the digestive tract before it is ever absorbed . Like the adrenergic agents , phenylephrine is effective in dilating the pupil , known as mydriasis ( Figure 15.14 ) . Phenylephrine is used during an eye exam in an ophthalmologist ’ s or optometrist ’ s office for this purpose . It can also be used to increase blood pressure in situations in which cardiac function is compromised , such as under anesthesia or during septic shock .", "hl_sentences": "A common sympathomimetic drug is phenylephrine , which is a common component of decongestants . Phenylephrine is known as an α 1 - adrenergic agonist , meaning that it binds to a specific adrenergic receptor , stimulating a response .", "question": { "cloze_format": "A drug is called an agonist if it ________.", "normal_format": "When is a drug called an agonist?", "question_choices": [ "blocks a receptor", "interferes with neurotransmitter reuptake", "acts like the endogenous neurotransmitter by binding to its receptor", "blocks the voltage-gated calcium ion channel" ], "question_id": "fs-id1483088", "question_text": "A drug is called an agonist if it ________." }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 2, "ans_text": "muscarinic agonist" }, "bloom": "1", "hl_context": "Atropine and scopolamine are part of a class of muscarinic antagonists that come from the Atropa genus of plants that include belladonna or deadly nightshade ( Figure 15.15 ) . The name of one of these plants , belladonna , refers to the fact that extracts from this plant were used cosmetically for dilating the pupil . The active chemicals from this plant block the muscarinic receptors in the iris and allow the pupil to dilate , which is considered attractive because it makes the eyes appear larger . Humans are instinctively attracted to anything with larger eyes , which comes from the fact that the ratio of eye-to-head size is different in infants ( or baby animals ) and can elicit an emotional response . The cosmetic use of belladonna extract was essentially acting on this response . Atropine is no longer used in this cosmetic capacity for reasons related to the other name for the plant , which is deadly nightshade . Suppression of parasympathetic function , especially when it becomes systemic , can be fatal . Autonomic regulation is disrupted and anticholinergic symptoms develop . The berries of this plant are highly toxic , but can be mistaken for other berries . <hl> The antidote for atropine or scopolamine poisoning is pilocarpine . <hl> <hl> Pilocarpine is a nonspecific muscarinic agonist commonly used to treat disorders of the eye . <hl> It reverses mydriasis , such as is caused by phenylephrine , and can be administered after an eye exam . Along with constricting the pupil through the smooth muscle of the iris , pilocarpine will also cause the ciliary muscle to contract . This will open perforations at the base of the cornea , allowing for the drainage of aqueous humor from the anterior compartment of the eye and , therefore , reducing intraocular pressure related to glaucoma .", "hl_sentences": "The antidote for atropine or scopolamine poisoning is pilocarpine . Pilocarpine is a nonspecific muscarinic agonist commonly used to treat disorders of the eye .", "question": { "cloze_format": "The ___ drug would be an antidote to atropine poisoning.", "normal_format": "Which type of drug would be an antidote to atropine poisoning?", "question_choices": [ "nicotinic agonist", "anticholinergic", "muscarinic agonist", "α-blocker" ], "question_id": "fs-id2278782", "question_text": "Which type of drug would be an antidote to atropine poisoning?" }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 3, "ans_text": "α-blocker" }, "bloom": "1", "hl_context": "<hl> Possibly the most familiar type of sympatholytic drug are the β-blockers . <hl> These drugs are often used to treat cardiovascular disease because they block the β-receptors associated with vasoconstriction and cardioacceleration . By allowing blood vessels to dilate , or keeping heart rate from increasing , these drugs can improve cardiac function in a compromised system , such as for a person with congestive heart failure or who has previously suffered a heart attack . A couple of common versions of β-blockers are metoprolol , which specifically blocks the β 1 - receptor , and propanolol , which nonspecifically blocks β-receptors . <hl> There are other drugs that are α-blockers and can affect the sympathetic system in a similar way . <hl> <hl> Other uses for sympatholytic drugs are as antianxiety medications . <hl> A common example of this is clonidine , which is an α-agonist . The sympathetic system is tied to anxiety to the point that the sympathetic response can be referred to as “ fight , flight , or fright . ” Clonidine is used for other treatments aside from hypertension and anxiety , including pain conditions and attention deficit hyperactivity disorder .", "hl_sentences": "Possibly the most familiar type of sympatholytic drug are the β-blockers . There are other drugs that are α-blockers and can affect the sympathetic system in a similar way . Other uses for sympatholytic drugs are as antianxiety medications .", "question": { "cloze_format": "___ is a kind of drug that would have anti-anxiety effects.", "normal_format": "Which kind of drug would have anti-anxiety effects?", "question_choices": [ "nicotinic agonist", "anticholinergic", "muscarinic agonist", "α-blocker" ], "question_id": "fs-id2006177", "question_text": "Which kind of drug would have anti-anxiety effects?" }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 1, "ans_text": "sympathomimetic drug" }, "bloom": "1", "hl_context": "<hl> A common sympathomimetic drug is phenylephrine , which is a common component of decongestants . <hl> It can also be used to dilate the pupil and to raise blood pressure . Phenylephrine is known as an α 1 - adrenergic agonist , meaning that it binds to a specific adrenergic receptor , stimulating a response . <hl> In this role , phenylephrine will bind to the adrenergic receptors in bronchioles of the lungs and cause them to dilate . <hl> <hl> By opening these structures , accumulated mucus can be cleared out of the lower respiratory tract . <hl> Phenylephrine is often paired with other pharmaceuticals , such as analgesics , as in the “ sinus ” version of many over-the-counter drugs , such as Tylenol Sinus ® or Excedrin Sinus ® , or in expectorants for chest congestion such as in Robitussin CF ® . A related molecule , called pseudoephedrine , was much more commonly used in these applications than was phenylephrine , until the molecule became useful in the illicit production of amphetamines . Phenylephrine is not as effective as a drug because it can be partially broken down in the digestive tract before it is ever absorbed . Like the adrenergic agents , phenylephrine is effective in dilating the pupil , known as mydriasis ( Figure 15.14 ) . Phenylephrine is used during an eye exam in an ophthalmologist ’ s or optometrist ’ s office for this purpose . It can also be used to increase blood pressure in situations in which cardiac function is compromised , such as under anesthesia or during septic shock .", "hl_sentences": "A common sympathomimetic drug is phenylephrine , which is a common component of decongestants . In this role , phenylephrine will bind to the adrenergic receptors in bronchioles of the lungs and cause them to dilate . By opening these structures , accumulated mucus can be cleared out of the lower respiratory tract .", "question": { "cloze_format": "The drug that could be used to treat asthma by opening airways wider is the ___ .", "normal_format": "Which type of drug could be used to treat asthma by opening airways wider?", "question_choices": [ "sympatholytic drug", "sympathomimetic drug", "anticholinergic drug", "parasympathomimetic drug" ], "question_id": "fs-id1632365", "question_text": "Which type of drug could be used to treat asthma by opening airways wider?" }, "references_are_paraphrase": 0 } ]
15
15.1 Divisions of the Autonomic Nervous System Learning Objectives By the end of this section, you will be able to: Name the components that generate the sympathetic and parasympathetic responses of the autonomic nervous system Explain the differences in output connections within the two divisions of the autonomic nervous system Describe the signaling molecules and receptor proteins involved in communication within the two divisions of the autonomic nervous system The nervous system can be divided into two functional parts: the somatic nervous system and the autonomic nervous system. The major differences between the two systems are evident in the responses that each produces. The somatic nervous system causes contraction of skeletal muscles. The autonomic nervous system controls cardiac and smooth muscle, as well as glandular tissue. The somatic nervous system is associated with voluntary responses (though many can happen without conscious awareness, like breathing), and the autonomic nervous system is associated with involuntary responses, such as those related to homeostasis. The autonomic nervous system regulates many of the internal organs through a balance of two aspects, or divisions. In addition to the endocrine system, the autonomic nervous system is instrumental in homeostatic mechanisms in the body. The two divisions of the autonomic nervous system are the sympathetic division and the parasympathetic division . The sympathetic system is associated with the fight-or-flight response , and parasympathetic activity is referred to by the epithet of rest and digest . Homeostasis is the balance between the two systems. At each target effector, dual innervation determines activity. For example, the heart receives connections from both the sympathetic and parasympathetic divisions. One causes heart rate to increase, whereas the other causes heart rate to decrease. Interactive Link Watch this video to learn more about adrenaline and the fight-or-flight response. When someone is said to have a rush of adrenaline, the image of bungee jumpers or skydivers usually comes to mind. But adrenaline, also known as epinephrine, is an important chemical in coordinating the body’s fight-or-flight response. In this video, you look inside the physiology of the fight-or-flight response, as envisioned for a firefighter. His body’s reaction is the result of the sympathetic division of the autonomic nervous system causing system-wide changes as it prepares for extreme responses. What two changes does adrenaline bring about to help the skeletal muscle response? Sympathetic Division of the Autonomic Nervous System To respond to a threat—to fight or to run away—the sympathetic system causes divergent effects as many different effector organs are activated together for a common purpose. More oxygen needs to be inhaled and delivered to skeletal muscle. The respiratory, cardiovascular, and musculoskeletal systems are all activated together. Additionally, sweating keeps the excess heat that comes from muscle contraction from causing the body to overheat. The digestive system shuts down so that blood is not absorbing nutrients when it should be delivering oxygen to skeletal muscles. To coordinate all these responses, the connections in the sympathetic system diverge from a limited region of the central nervous system (CNS) to a wide array of ganglia that project to the many effector organs simultaneously. The complex set of structures that compose the output of the sympathetic system make it possible for these disparate effectors to come together in a coordinated, systemic change. The sympathetic division of the autonomic nervous system influences the various organ systems of the body through connections emerging from the thoracic and upper lumbar spinal cord. It is referred to as the thoracolumbar system to reflect this anatomical basis. A central neuron in the lateral horn of any of these spinal regions projects to ganglia adjacent to the vertebral column through the ventral spinal roots. The majority of ganglia of the sympathetic system belong to a network of sympathetic chain ganglia that runs alongside the vertebral column. The ganglia appear as a series of clusters of neurons linked by axonal bridges. There are typically 23 ganglia in the chain on either side of the spinal column. Three correspond to the cervical region, 12 are in the thoracic region, four are in the lumbar region, and four correspond to the sacral region. The cervical and sacral levels are not connected to the spinal cord directly through the spinal roots, but through ascending or descending connections through the bridges within the chain. A diagram that shows the connections of the sympathetic system is somewhat like a circuit diagram that shows the electrical connections between different receptacles and devices. In Figure 15.2 , the “circuits” of the sympathetic system are intentionally simplified. To continue with the analogy of the circuit diagram, there are three different types of “junctions” that operate within the sympathetic system ( Figure 15.3 ). The first type is most direct: the sympathetic nerve projects to the chain ganglion at the same level as the target effector (the organ, tissue, or gland to be innervated). An example of this type is spinal nerve T1 that synapses with the T1 chain ganglion to innervate the trachea. The fibers of this branch are called white rami communicantes (singular = ramus communicans); they are myelinated and therefore referred to as white (see Figure 15.3 a ). The axon from the central neuron (the preganglionic fiber shown as a solid line) synapses with the ganglionic neuron (with the postganglionic fiber shown as a dashed line). This neuron then projects to a target effector—in this case, the trachea—via gray rami communicantes , which are unmyelinated axons. In some cases, the target effectors are located superior or inferior to the spinal segment at which the preganglionic fiber emerges. With respect to the “wiring” involved, the synapse with the ganglionic neuron occurs at chain ganglia superior or inferior to the location of the central neuron. An example of this is spinal nerve T1 that innervates the eye. The spinal nerve tracks up through the chain until it reaches the superior cervical ganglion , where it synapses with the postganglionic neuron (see Figure 15.3 b ). The cervical ganglia are referred to as paravertebral ganglia , given their location adjacent to prevertebral ganglia in the sympathetic chain. Not all axons from the central neurons terminate in the chain ganglia. Additional branches from the ventral nerve root continue through the chain and on to one of the collateral ganglia as the greater splanchnic nerve or lesser splanchnic nerve . For example, the greater splanchnic nerve at the level of T5 synapses with a collateral ganglion outside the chain before making the connection to the postganglionic nerves that innervate the stomach (see Figure 15.3 c ). Collateral ganglia , also called prevertebral ganglia , are situated anterior to the vertebral column and receive inputs from splanchnic nerves as well as central sympathetic neurons. They are associated with controlling organs in the abdominal cavity, and are also considered part of the enteric nervous system. The three collateral ganglia are the celiac ganglion , the superior mesenteric ganglion , and the inferior mesenteric ganglion (see Figure 15.2 ). The word celiac is derived from the Latin word “coelom,” which refers to a body cavity (in this case, the abdominal cavity), and the word mesenteric refers to the digestive system. An axon from the central neuron that projects to a sympathetic ganglion is referred to as a preganglionic fiber or neuron, and represents the output from the CNS to the ganglion. Because the sympathetic ganglia are adjacent to the vertebral column, preganglionic sympathetic fibers are relatively short, and they are myelinated. A postganglionic fiber —the axon from a ganglionic neuron that projects to the target effector—represents the output of a ganglion that directly influences the organ. Compared with the preganglionic fibers, postganglionic sympathetic fibers are long because of the relatively greater distance from the ganglion to the target effector. These fibers are unmyelinated. (Note that the term “postganglionic neuron” may be used to describe the projection from a ganglion to the target. The problem with that usage is that the cell body is in the ganglion, and only the fiber is postganglionic. Typically, the term neuron applies to the entire cell.) One type of preganglionic sympathetic fiber does not terminate in a ganglion. These are the axons from central sympathetic neurons that project to the adrenal medulla , the interior portion of the adrenal gland. These axons are still referred to as preganglionic fibers, but the target is not a ganglion. The adrenal medulla releases signaling molecules into the bloodstream, rather than using axons to communicate with target structures. The cells in the adrenal medulla that are contacted by the preganglionic fibers are called chromaffin cells . These cells are neurosecretory cells that develop from the neural crest along with the sympathetic ganglia, reinforcing the idea that the gland is, functionally, a sympathetic ganglion. The projections of the sympathetic division of the autonomic nervous system diverge widely, resulting in a broad influence of the system throughout the body. As a response to a threat, the sympathetic system would increase heart rate and breathing rate and cause blood flow to the skeletal muscle to increase and blood flow to the digestive system to decrease. Sweat gland secretion should also increase as part of an integrated response. All of those physiological changes are going to be required to occur together to run away from the hunting lioness, or the modern equivalent. This divergence is seen in the branching patterns of preganglionic sympathetic neurons—a single preganglionic sympathetic neuron may have 10–20 targets. An axon that leaves a central neuron of the lateral horn in the thoracolumbar spinal cord will pass through the white ramus communicans and enter the sympathetic chain, where it will branch toward a variety of targets. At the level of the spinal cord at which the preganglionic sympathetic fiber exits the spinal cord, a branch will synapse on a neuron in the adjacent chain ganglion. Some branches will extend up or down to a different level of the chain ganglia. Other branches will pass through the chain ganglia and project through one of the splanchnic nerves to a collateral ganglion. Finally, some branches may project through the splanchnic nerves to the adrenal medulla. All of these branches mean that one preganglionic neuron can influence different regions of the sympathetic system very broadly, by acting on widely distributed organs. Parasympathetic Division of the Autonomic Nervous System The parasympathetic division of the autonomic nervous system is named because its central neurons are located on either side of the thoracolumbar region of the spinal cord (para- = “beside” or “near”). The parasympathetic system can also be referred to as the craniosacral system (or outflow) because the preganglionic neurons are located in nuclei of the brain stem and the lateral horn of the sacral spinal cord. The connections, or “circuits,” of the parasympathetic division are similar to the general layout of the sympathetic division with a few specific differences ( Figure 15.4 ). The preganglionic fibers from the cranial region travel in cranial nerves, whereas preganglionic fibers from the sacral region travel in spinal nerves. The targets of these fibers are terminal ganglia , which are located near—or even within—the target effector. These ganglia are often referred to as intramural ganglia when they are found within the walls of the target organ. The postganglionic fiber projects from the terminal ganglia a short distance to the target effector, or to the specific target tissue within the organ. Comparing the relative lengths of axons in the parasympathetic system, the preganglionic fibers are long and the postganglionic fibers are short because the ganglia are close to—and sometimes within—the target effectors. The cranial component of the parasympathetic system is based in particular nuclei of the brain stem. In the midbrain, the Edinger–Westphal nucleus is part of the oculomotor complex, and axons from those neurons travel with the fibers in the oculomotor nerve (cranial nerve III) that innervate the extraocular muscles. The preganglionic parasympathetic fibers within cranial nerve III terminate in the ciliary ganglion , which is located in the posterior orbit. The postganglionic parasympathetic fibers then project to the smooth muscle of the iris to control pupillary size. In the upper medulla, the salivatory nuclei contain neurons with axons that project through the facial and glossopharyngeal nerves to ganglia that control salivary glands. Tear production is influenced by parasympathetic fibers in the facial nerve, which activate a ganglion, and ultimately the lacrimal (tear) gland. Neurons in the dorsal nucleus of the vagus nerve and the nucleus ambiguus project through the vagus nerve (cranial nerve X) to the terminal ganglia of the thoracic and abdominal cavities. Parasympathetic preganglionic fibers primarily influence the heart, bronchi, and esophagus in the thoracic cavity and the stomach, liver, pancreas, gall bladder, and small intestine of the abdominal cavity. The postganglionic fibers from the ganglia activated by the vagus nerve are often incorporated into the structure of the organ, such as the mesenteric plexus of the digestive tract organs and the intramural ganglia. Chemical Signaling in the Autonomic Nervous System Where an autonomic neuron connects with a target, there is a synapse. The electrical signal of the action potential causes the release of a signaling molecule, which will bind to receptor proteins on the target cell. Synapses of the autonomic system are classified as either cholinergic , meaning that acetylcholine (ACh) is released, or adrenergic , meaning that norepinephrine is released. The terms cholinergic and adrenergic refer not only to the signaling molecule that is released but also to the class of receptors that each binds. The cholinergic system includes two classes of receptor: the nicotinic receptor and the muscarinic receptor . Both receptor types bind to ACh and cause changes in the target cell. The nicotinic receptor is a ligand-gated cation channel and the muscarinic receptor is a G protein–coupled receptor . The receptors are named for, and differentiated by, other molecules that bind to them. Whereas nicotine will bind to the nicotinic receptor, and muscarine will bind to the muscarinic receptor, there is no cross-reactivity between the receptors. The situation is similar to locks and keys. Imagine two locks—one for a classroom and the other for an office—that are opened by two separate keys. The classroom key will not open the office door and the office key will not open the classroom door. This is similar to the specificity of nicotine and muscarine for their receptors. However, a master key can open multiple locks, such as a master key for the Biology Department that opens both the classroom and the office doors. This is similar to ACh that binds to both types of receptors. The molecules that define these receptors are not crucial—they are simply tools for researchers to use in the laboratory. These molecules are exogenous , meaning that they are made outside of the human body, so a researcher can use them without any confounding endogenous results (results caused by the molecules produced in the body). The adrenergic system also has two types of receptors, named the alpha (α)-adrenergic receptor and beta (β)-adrenergic receptor . Unlike cholinergic receptors, these receptor types are not classified by which drugs can bind to them. All of them are G protein–coupled receptors. There are two types of α-adrenergic receptors, termed α 1 , and α 2 , and there are three types of β-adrenergic receptors, termed β 1 , β 2 and β 3 . An additional aspect of the adrenergic system is that there is a second signaling molecule called epinephrine . The chemical difference between norepinephrine and epinephrine is the addition of a methyl group (CH 3 ) in epinephrine. The prefix “nor-” actually refers to this chemical difference, in which a methyl group is missing. The term adrenergic should remind you of the word adrenaline, which is associated with the fight-or-flight response described at the beginning of the chapter. Adrenaline and epinephrine are two names for the same molecule. The adrenal gland (in Latin, ad- = “on top of”; renal = “kidney”) secretes adrenaline. The ending “-ine” refers to the chemical being derived, or extracted, from the adrenal gland. A similar construction from Greek instead of Latin results in the word epinephrine (epi- = “above”; nephr- = “kidney”). In scientific usage, epinephrine is preferred in the United States, whereas adrenaline is preferred in Great Britain, because “adrenalin” was once a registered, proprietary drug name in the United States. Though the drug is no longer sold, the convention of referring to this molecule by the two different names persists. Similarly, norepinephrine and noradrenaline are two names for the same molecule. Having understood the cholinergic and adrenergic systems, their role in the autonomic system is relatively simple to understand. All preganglionic fibers, both sympathetic and parasympathetic, release ACh. All ganglionic neurons—the targets of these preganglionic fibers—have nicotinic receptors in their cell membranes. The nicotinic receptor is a ligand-gated cation channel that results in depolarization of the postsynaptic membrane. The postganglionic parasympathetic fibers also release ACh, but the receptors on their targets are muscarinic receptors, which are G protein–coupled receptors and do not exclusively cause depolarization of the postsynaptic membrane. Postganglionic sympathetic fibers release norepinephrine, except for fibers that project to sweat glands and to blood vessels associated with skeletal muscles, which release ACh ( Table 15.1 ). Autonomic System Signaling Molecules Sympathetic Parasympathetic Preganglionic Acetylcholine → nicotinic receptor Acetylcholine → nicotinic receptor Postganglionic Norepinephrine → α- or β-adrenergic receptors Acetylcholine → muscarinic receptor (associated with sweat glands and the blood vessels associated with skeletal muscles only Acetylcholine → muscarinic receptor Table 15.1 Signaling molecules can belong to two broad groups. Neurotransmitters are released at synapses, whereas hormones are released into the bloodstream. These are simplistic definitions, but they can help to clarify this point. Acetylcholine can be considered a neurotransmitter because it is released by axons at synapses. The adrenergic system, however, presents a challenge. Postganglionic sympathetic fibers release norepinephrine, which can be considered a neurotransmitter. But the adrenal medulla releases epinephrine and norepinephrine into circulation, so they should be considered hormones. What are referred to here as synapses may not fit the strictest definition of synapse. Some sources will refer to the connection between a postganglionic fiber and a target effector as neuroeffector junctions; neurotransmitters, as defined above, would be called neuromodulators. The structure of postganglionic connections are not the typical synaptic end bulb that is found at the neuromuscular junction, but rather are chains of swellings along the length of a postganglionic fiber called a varicosity ( Figure 15.5 ). Everyday Connection Fight or Flight? What About Fright and Freeze? The original usage of the epithet “fight or flight” comes from a scientist named Walter Cannon who worked at Harvard in 1915. The concept of homeostasis and the functioning of the sympathetic system had been introduced in France in the previous century. Cannon expanded the idea, and introduced the idea that an animal responds to a threat by preparing to stand and fight or run away. The nature of this response was thoroughly explained in a book on the physiology of pain, hunger, fear, and rage. When students learn about the sympathetic system and the fight-or-flight response, they often stop and wonder about other responses. If you were faced with a lioness running toward you as pictured at the beginning of this chapter, would you run or would you stand your ground? Some people would say that they would freeze and not know what to do. So isn’t there really more to what the autonomic system does than fight, flight, rest, or digest. What about fear and paralysis in the face of a threat? The common epithet of “fight or flight” is being enlarged to be “fight, flight, or fright” or even “fight, flight, fright, or freeze.” Cannon’s original contribution was a catchy phrase to express some of what the nervous system does in response to a threat, but it is incomplete. The sympathetic system is responsible for the physiological responses to emotional states. The name “sympathetic” can be said to mean that (sym- = “together”; -pathos = “pain,” “suffering,” or “emotion”). Interactive Link Watch this video to learn more about the nervous system. As described in this video, the nervous system has a way to deal with threats and stress that is separate from the conscious control of the somatic nervous system. The system comes from a time when threats were about survival, but in the modern age, these responses become part of stress and anxiety. This video describes how the autonomic system is only part of the response to threats, or stressors. What other organ system gets involved, and what part of the brain coordinates the two systems for the entire response, including epinephrine (adrenaline) and cortisol? 15.2 Autonomic Reflexes and Homeostasis Learning Objectives By the end of this section, you will be able to: Compare the structure of somatic and autonomic reflex arcs Explain the differences in sympathetic and parasympathetic reflexes Differentiate between short and long reflexes Determine the effect of the autonomic nervous system on the regulation of the various organ systems on the basis of the signaling molecules involved Describe the effects of drugs that affect autonomic function The autonomic nervous system regulates organ systems through circuits that resemble the reflexes described in the somatic nervous system. The main difference between the somatic and autonomic systems is in what target tissues are effectors. Somatic responses are solely based on skeletal muscle contraction. The autonomic system, however, targets cardiac and smooth muscle, as well as glandular tissue. Whereas the basic circuit is a reflex arc , there are differences in the structure of those reflexes for the somatic and autonomic systems. The Structure of Reflexes One difference between a somatic reflex , such as the withdrawal reflex, and a visceral reflex , which is an autonomic reflex, is in the efferent branch . The output of a somatic reflex is the lower motor neuron in the ventral horn of the spinal cord that projects directly to a skeletal muscle to cause its contraction. The output of a visceral reflex is a two-step pathway starting with the preganglionic fiber emerging from a lateral horn neuron in the spinal cord, or a cranial nucleus neuron in the brain stem, to a ganglion—followed by the postganglionic fiber projecting to a target effector. The other part of a reflex, the afferent branch , is often the same between the two systems. Sensory neurons receiving input from the periphery—with cell bodies in the sensory ganglia, either of a cranial nerve or a dorsal root ganglion adjacent to the spinal cord—project into the CNS to initiate the reflex ( Figure 15.6 ). The Latin root “effere” means “to carry.” Adding the prefix “ef-” suggests the meaning “to carry away,” whereas adding the prefix “af-” suggests “to carry toward or inward.” Afferent Branch The afferent branch of a reflex arc does differ between somatic and visceral reflexes in some instances. Many of the inputs to visceral reflexes are from special or somatic senses, but particular senses are associated with the viscera that are not part of the conscious perception of the environment through the somatic nervous system. For example, there is a specific type of mechanoreceptor, called a baroreceptor , in the walls of the aorta and carotid sinuses that senses the stretch of those organs when blood volume or pressure increases. You do not have a conscious perception of having high blood pressure, but that is an important afferent branch of the cardiovascular and, particularly, vasomotor reflexes. The sensory neuron is essentially the same as any other general sensory neuron. The baroreceptor apparatus is part of the ending of a unipolar neuron that has a cell body in a sensory ganglion. The baroreceptors from the carotid arteries have axons in the glossopharyngeal nerve, and those from the aorta have axons in the vagus nerve. Though visceral senses are not primarily a part of conscious perception, those sensations sometimes make it to conscious awareness. If a visceral sense is strong enough, it will be perceived. The sensory homunculus—the representation of the body in the primary somatosensory cortex—only has a small region allotted for the perception of internal stimuli. If you swallow a large bolus of food, for instance, you will probably feel the lump of that food as it pushes through your esophagus, or even if your stomach is distended after a large meal. If you inhale especially cold air, you can feel it as it enters your larynx and trachea. These sensations are not the same as feeling high blood pressure or blood sugar levels. When particularly strong visceral sensations rise to the level of conscious perception, the sensations are often felt in unexpected places. For example, strong visceral sensations of the heart will be felt as pain in the left shoulder and left arm. This irregular pattern of projection of conscious perception of visceral sensations is called referred pain . Depending on the organ system affected, the referred pain will project to different areas of the body ( Figure 15.7 ). The location of referred pain is not random, but a definitive explanation of the mechanism has not been established. The most broadly accepted theory for this phenomenon is that the visceral sensory fibers enter into the same level of the spinal cord as the somatosensory fibers of the referred pain location. By this explanation, the visceral sensory fibers from the mediastinal region, where the heart is located, would enter the spinal cord at the same level as the spinal nerves from the shoulder and arm, so the brain misinterprets the sensations from the mediastinal region as being from the axillary and brachial regions. Projections from the medial and inferior divisions of the cervical ganglia do enter the spinal cord at the middle to lower cervical levels, which is where the somatosensory fibers enter. Disorders of the... Nervous System: Kehr’s Sign Kehr’s sign is the presentation of pain in the left shoulder, chest, and neck regions following rupture of the spleen. The spleen is in the upper-left abdominopelvic quadrant, but the pain is more in the shoulder and neck. How can this be? The sympathetic fibers connected to the spleen are from the celiac ganglion, which would be from the mid-thoracic to lower thoracic region whereas parasympathetic fibers are found in the vagus nerve, which connects in the medulla of the brain stem. However, the neck and shoulder would connect to the spinal cord at the mid-cervical level of the spinal cord. These connections do not fit with the expected correspondence of visceral and somatosensory fibers entering at the same level of the spinal cord. The incorrect assumption would be that the visceral sensations are coming from the spleen directly. In fact, the visceral fibers are coming from the diaphragm. The nerve connecting to the diaphragm takes a special route. The phrenic nerve is connected to the spinal cord at cervical levels 3 to 5. The motor fibers that make up this nerve are responsible for the muscle contractions that drive ventilation. These fibers have left the spinal cord to enter the phrenic nerve, meaning that spinal cord damage below the mid-cervical level is not fatal by making ventilation impossible. Therefore, the visceral fibers from the diaphragm enter the spinal cord at the same level as the somatosensory fibers from the neck and shoulder. The diaphragm plays a role in Kehr’s sign because the spleen is just inferior to the diaphragm in the upper-left quadrant of the abdominopelvic cavity. When the spleen ruptures, blood spills into this region. The accumulating hemorrhage then puts pressure on the diaphragm. The visceral sensation is actually in the diaphragm, so the referred pain is in a region of the body that corresponds to the diaphragm, not the spleen. Efferent Branch The efferent branch of the visceral reflex arc begins with the projection from the central neuron along the preganglionic fiber. This fiber then makes a synapse on the ganglionic neuron that projects to the target effector. The effector organs that are the targets of the autonomic system range from the iris and ciliary body of the eye to the urinary bladder and reproductive organs. The thoracolumbar output, through the various sympathetic ganglia, reaches all of these organs. The cranial component of the parasympathetic system projects from the eye to part of the intestines. The sacral component picks up with the majority of the large intestine and the pelvic organs of the urinary and reproductive systems. Short and Long Reflexes Somatic reflexes involve sensory neurons that connect sensory receptors to the CNS and motor neurons that project back out to the skeletal muscles. Visceral reflexes that involve the thoracolumbar or craniosacral systems share similar connections. However, there are reflexes that do not need to involve any CNS components. A long reflex has afferent branches that enter the spinal cord or brain and involve the efferent branches, as previously explained. A short reflex is completely peripheral and only involves the local integration of sensory input with motor output ( Figure 15.8 ). The difference between short and long reflexes is in the involvement of the CNS. Somatic reflexes always involve the CNS, even in a monosynaptic reflex in which the sensory neuron directly activates the motor neuron. That synapse is in the spinal cord or brain stem, so it has to involve the CNS. However, in the autonomic system there is the possibility that the CNS is not involved. Because the efferent branch of a visceral reflex involves two neurons—the central neuron and the ganglionic neuron—a “short circuit” can be possible. If a sensory neuron projects directly to the ganglionic neuron and causes it to activate the effector target, then the CNS is not involved. A division of the nervous system that is related to the autonomic nervous system is the enteric nervous system. The word enteric refers to the digestive organs, so this represents the nervous tissue that is part of the digestive system. There are a few myenteric plexuses in which the nervous tissue in the wall of the digestive tract organs can directly influence digestive function. If stretch receptors in the stomach are activated by the filling and distension of the stomach, a short reflex will directly activate the smooth muscle fibers of the stomach wall to increase motility to digest the excessive food in the stomach. No CNS involvement is needed because the stretch receptor is directly activating a neuron in the wall of the stomach that causes the smooth muscle to contract. That neuron, connected to the smooth muscle, is a postganglionic parasympathetic neuron that can be controlled by a fiber found in the vagus nerve. Interactive Link Read this article to learn about a teenager who experiences a series of spells that suggest a stroke. He undergoes endless tests and seeks input from multiple doctors. In the end, one expert, one question, and a simple blood pressure cuff answers the question. Why would the heart have to beat faster when the teenager changes his body position from lying down to sitting, and then to standing? Balance in Competing Autonomic Reflex Arcs The autonomic nervous system is important for homeostasis because its two divisions compete at the target effector. The balance of homeostasis is attributable to the competing inputs from the sympathetic and parasympathetic divisions (dual innervation). At the level of the target effector, the signal of which system is sending the message is strictly chemical. A signaling molecule binds to a receptor that causes changes in the target cell, which in turn causes the tissue or organ to respond to the changing conditions of the body. Competing Neurotransmitters The postganglionic fibers of the sympathetic and parasympathetic divisions both release neurotransmitters that bind to receptors on their targets. Postganglionic sympathetic fibers release norepinephrine, with a minor exception, whereas postganglionic parasympathetic fibers release ACh. For any given target, the difference in which division of the autonomic nervous system is exerting control is just in what chemical binds to its receptors. The target cells will have adrenergic and muscarinic receptors. If norepinephrine is released, it will bind to the adrenergic receptors present on the target cell, and if ACh is released, it will bind to the muscarinic receptors on the target cell. In the sympathetic system, there are exceptions to this pattern of dual innervation. The postganglionic sympathetic fibers that contact the blood vessels within skeletal muscle and that contact sweat glands do not release norepinephrine, they release ACh. This does not create any problem because there is no parasympathetic input to the sweat glands. Sweat glands have muscarinic receptors and produce and secrete sweat in response to the presence of ACh. At most of the other targets of the autonomic system, the effector response is based on which neurotransmitter is released and what receptor is present. For example, regions of the heart that establish heart rate are contacted by postganglionic fibers from both systems. If norepinephrine is released onto those cells, it binds to an adrenergic receptor that causes the cells to depolarize faster, and the heart rate increases. If ACh is released onto those cells, it binds to a muscarinic receptor that causes the cells to hyperpolarize so that they cannot reach threshold as easily, and the heart rate slows. Without this parasympathetic input, the heart would work at a rate of approximately 100 beats per minute (bpm). The sympathetic system speeds that up, as it would during exercise, to 120–140 bpm, for example. The parasympathetic system slows it down to the resting heart rate of 60–80 bpm. Another example is in the control of pupillary size ( Figure 15.9 ). The afferent branch responds to light hitting the retina. Photoreceptors are activated, and the signal is transferred to the retinal ganglion cells that send an action potential along the optic nerve into the diencephalon. If light levels are low, the sympathetic system sends a signal out through the upper thoracic spinal cord to the superior cervical ganglion of the sympathetic chain. The postganglionic fiber then projects to the iris, where it releases norepinephrine onto the radial fibers of the iris (a smooth muscle). When those fibers contract, the pupil dilates—increasing the amount of light hitting the retina. If light levels are too high, the parasympathetic system sends a signal out from the Edinger–Westphal nucleus through the oculomotor nerve. This fiber synapses in the ciliary ganglion in the posterior orbit. The postganglionic fiber then projects to the iris, where it releases ACh onto the circular fibers of the iris—another smooth muscle. When those fibers contract, the pupil constricts to limit the amount of light hitting the retina. In this example, the autonomic system is controlling how much light hits the retina. It is a homeostatic reflex mechanism that keeps the activation of photoreceptors within certain limits. In the context of avoiding a threat like the lioness on the savannah, the sympathetic response for fight or flight will increase pupillary diameter so that more light hits the retina and more visual information is available for running away. Likewise, the parasympathetic response of rest reduces the amount of light reaching the retina, allowing the photoreceptors to cycle through bleaching and be regenerated for further visual perception; this is what the homeostatic process is attempting to maintain. Interactive Link Watch this video to learn about the pupillary reflexes. The pupillary light reflex involves sensory input through the optic nerve and motor response through the oculomotor nerve to the ciliary ganglion, which projects to the circular fibers of the iris. As shown in this short animation, pupils will constrict to limit the amount of light falling on the retina under bright lighting conditions. What constitutes the afferent and efferent branches of the competing reflex (dilation)? Autonomic Tone Organ systems are balanced between the input from the sympathetic and parasympathetic divisions. When something upsets that balance, the homeostatic mechanisms strive to return it to its regular state. For each organ system, there may be more of a sympathetic or parasympathetic tendency to the resting state, which is known as the autonomic tone of the system. For example, the heart rate was described above. Because the resting heart rate is the result of the parasympathetic system slowing the heart down from its intrinsic rate of 100 bpm, the heart can be said to be in parasympathetic tone. In a similar fashion, another aspect of the cardiovascular system is primarily under sympathetic control. Blood pressure is partially determined by the contraction of smooth muscle in the walls of blood vessels. These tissues have adrenergic receptors that respond to the release of norepinephrine from postganglionic sympathetic fibers by constricting and increasing blood pressure. The hormones released from the adrenal medulla—epinephrine and norepinephrine—will also bind to these receptors. Those hormones travel through the bloodstream where they can easily interact with the receptors in the vessel walls. The parasympathetic system has no significant input to the systemic blood vessels, so the sympathetic system determines their tone. There are a limited number of blood vessels that respond to sympathetic input in a different fashion. Blood vessels in skeletal muscle, particularly those in the lower limbs, are more likely to dilate. It does not have an overall effect on blood pressure to alter the tone of the vessels, but rather allows for blood flow to increase for those skeletal muscles that will be active in the fight-or-flight response. The blood vessels that have a parasympathetic projection are limited to those in the erectile tissue of the reproductive organs. Acetylcholine released by these postganglionic parasympathetic fibers cause the vessels to dilate, leading to the engorgement of the erectile tissue. Homeostatic Imbalances Orthostatic Hypotension Have you ever stood up quickly and felt dizzy for a moment? This is because, for one reason or another, blood is not getting to your brain so it is briefly deprived of oxygen. When you change position from sitting or lying down to standing, your cardiovascular system has to adjust for a new challenge, keeping blood pumping up into the head while gravity is pulling more and more blood down into the legs. The reason for this is a sympathetic reflex that maintains the output of the heart in response to postural change. When a person stands up, proprioceptors indicate that the body is changing position. A signal goes to the CNS, which then sends a signal to the upper thoracic spinal cord neurons of the sympathetic division. The sympathetic system then causes the heart to beat faster and the blood vessels to constrict. Both changes will make it possible for the cardiovascular system to maintain the rate of blood delivery to the brain. Blood is being pumped superiorly through the internal branch of the carotid arteries into the brain, against the force of gravity. Gravity is not increasing while standing, but blood is more likely to flow down into the legs as they are extended for standing. This sympathetic reflex keeps the brain well oxygenated so that cognitive and other neural processes are not interrupted. Sometimes this does not work properly. If the sympathetic system cannot increase cardiac output, then blood pressure into the brain will decrease, and a brief neurological loss can be felt. This can be brief, as a slight “wooziness” when standing up too quickly, or a loss of balance and neurological impairment for a period of time. The name for this is orthostatic hypotension, which means that blood pressure goes below the homeostatic set point when standing. It can be the result of standing up faster than the reflex can occur, which may be referred to as a benign “head rush,” or it may be the result of an underlying cause. There are two basic reasons that orthostatic hypotension can occur. First, blood volume is too low and the sympathetic reflex is not effective. This hypovolemia may be the result of dehydration or medications that affect fluid balance, such as diuretics or vasodilators. Both of these medications are meant to lower blood pressure, which may be necessary in the case of systemic hypertension, and regulation of the medications may alleviate the problem. Sometimes increasing fluid intake or water retention through salt intake can improve the situation. The second underlying cause of orthostatic hypotension is autonomic failure. There are several disorders that result in compromised sympathetic functions. The disorders range from diabetes to multiple system atrophy (a loss of control over many systems in the body), and addressing the underlying condition can improve the hypotension. For example, with diabetes, peripheral nerve damage can occur, which would affect the postganglionic sympathetic fibers. Getting blood glucose levels under control can improve neurological deficits associated with diabetes. 15.3 Central Control Learning Objectives By the end of this section, you will be able to: Describe the role of higher centers of the brain in autonomic regulation Explain the connection of the hypothalamus to homeostasis Describe the regions of the CNS that link the autonomic system with emotion Describe the pathways important to descending control of the autonomic system The pupillary light reflex ( Figure 15.10 ) begins when light hits the retina and causes a signal to travel along the optic nerve. This is visual sensation, because the afferent branch of this reflex is simply sharing the special sense pathway. Bright light hitting the retina leads to the parasympathetic response, through the oculomotor nerve, followed by the postganglionic fiber from the ciliary ganglion, which stimulates the circular fibers of the iris to contract and constrict the pupil. When light hits the retina in one eye, both pupils contract. When that light is removed, both pupils dilate again back to the resting position. When the stimulus is unilateral (presented to only one eye), the response is bilateral (both eyes). The same is not true for somatic reflexes. If you touch a hot radiator, you only pull that arm back, not both. Central control of autonomic reflexes is different than for somatic reflexes. The hypothalamus, along with other CNS locations, controls the autonomic system. Forebrain Structures Autonomic control is based on the visceral reflexes, composed of the afferent and efferent branches. These homeostatic mechanisms are based on the balance between the two divisions of the autonomic system, which results in tone for various organs that is based on the predominant input from the sympathetic or parasympathetic systems. Coordinating that balance requires integration that begins with forebrain structures like the hypothalamus and continues into the brain stem and spinal cord. The Hypothalamus The hypothalamus is the control center for many homeostatic mechanisms. It regulates both autonomic function and endocrine function. The roles it plays in the pupillary reflexes demonstrates the importance of this control center. The optic nerve projects primarily to the thalamus, which is the necessary relay to the occipital cortex for conscious visual perception. Another projection of the optic nerve, however, goes to the hypothalamus. The hypothalamus then uses this visual system input to drive the pupillary reflexes. If the retina is activated by high levels of light, the hypothalamus stimulates the parasympathetic response. If the optic nerve message shows that low levels of light are falling on the retina, the hypothalamus activates the sympathetic response. Output from the hypothalamus follows two main tracts, the dorsal longitudinal fasciculus and the medial forebrain bundle ( Figure 15.11 ). Along these two tracts, the hypothalamus can influence the Edinger–Westphal nucleus of the oculomotor complex or the lateral horns of the thoracic spinal cord. These two tracts connect the hypothalamus with the major parasympathetic nuclei in the brain stem and the preganglionic (central) neurons of the thoracolumbar spinal cord. The hypothalamus also receives input from other areas of the forebrain through the medial forebrain bundle. The olfactory cortex, the septal nuclei of the basal forebrain, and the amygdala project into the hypothalamus through the medial forebrain bundle. These forebrain structures inform the hypothalamus about the state of the nervous system and can influence the regulatory processes of homeostasis. A good example of this is found in the amygdala, which is found beneath the cerebral cortex of the temporal lobe and plays a role in our ability to remember and feel emotions. The Amygdala The amygdala is a group of nuclei in the medial region of the temporal lobe that is part of the limbic lobe ( Figure 15.12 ). The limbic lobe includes structures that are involved in emotional responses, as well as structures that contribute to memory function. The limbic lobe has strong connections with the hypothalamus and influences the state of its activity on the basis of emotional state. For example, when you are anxious or scared, the amygdala will send signals to the hypothalamus along the medial forebrain bundle that will stimulate the sympathetic fight-or-flight response. The hypothalamus will also stimulate the release of stress hormones through its control of the endocrine system in response to amygdala input. The Medulla The medulla contains nuclei referred to as the cardiovascular center , which controls the smooth and cardiac muscle of the cardiovascular system through autonomic connections. When the homeostasis of the cardiovascular system shifts, such as when blood pressure changes, the coordination of the autonomic system can be accomplished within this region. Furthermore, when descending inputs from the hypothalamus stimulate this area, the sympathetic system can increase activity in the cardiovascular system, such as in response to anxiety or stress. The preganglionic sympathetic fibers that are responsible for increasing heart rate are referred to as the cardiac accelerator nerves , whereas the preganglionic sympathetic fibers responsible for constricting blood vessels compose the vasomotor nerves . Several brain stem nuclei are important for the visceral control of major organ systems. One brain stem nucleus involved in cardiovascular function is the solitary nucleus. It receives sensory input about blood pressure and cardiac function from the glossopharyngeal and vagus nerves, and its output will activate sympathetic stimulation of the heart or blood vessels through the upper thoracic lateral horn. Another brain stem nucleus important for visceral control is the dorsal motor nucleus of the vagus nerve, which is the motor nucleus for the parasympathetic functions ascribed to the vagus nerve, including decreasing the heart rate, relaxing bronchial tubes in the lungs, and activating digestive function through the enteric nervous system. The nucleus ambiguus, which is named for its ambiguous histology, also contributes to the parasympathetic output of the vagus nerve and targets muscles in the pharynx and larynx for swallowing and speech, as well as contributing to the parasympathetic tone of the heart along with the dorsal motor nucleus of the vagus. Everyday Connection Exercise and the Autonomic System In addition to its association with the fight-or-flight response and rest-and-digest functions, the autonomic system is responsible for certain everyday functions. For example, it comes into play when homeostatic mechanisms dynamically change, such as the physiological changes that accompany exercise. Getting on the treadmill and putting in a good workout will cause the heart rate to increase, breathing to be stronger and deeper, sweat glands to activate, and the digestive system to suspend activity. These are the same physiological changes associated with the fight-or-flight response, but there is nothing chasing you on that treadmill. This is not a simple homeostatic mechanism at work because “maintaining the internal environment” would mean getting all those changes back to their set points. Instead, the sympathetic system has become active during exercise so that your body can cope with what is happening. A homeostatic mechanism is dealing with the conscious decision to push the body away from a resting state. The heart, actually, is moving away from its homeostatic set point. Without any input from the autonomic system, the heart would beat at approximately 100 bpm, and the parasympathetic system slows that down to the resting rate of approximately 70 bpm. But in the middle of a good workout, you should see your heart rate at 120–140 bpm. You could say that the body is stressed because of what you are doing to it. Homeostatic mechanisms are trying to keep blood pH in the normal range, or to keep body temperature under control, but those are in response to the choice to exercise. Interactive Link Watch this video to learn about physical responses to emotion. The autonomic system, which is important for regulating the homeostasis of the organ systems, is also responsible for our physiological responses to emotions such as fear. The video summarizes the extent of the body’s reactions and describes several effects of the autonomic system in response to fear. On the basis of what you have already studied about autonomic function, which effect would you expect to be associated with parasympathetic, rather than sympathetic, activity? 15.4 Drugs that Affect the Autonomic System Learning Objectives By the end of this section, you will be able to: List the classes of pharmaceuticals that interact with the autonomic nervous system Differentiate between cholinergic and adrenergic compounds Differentiate between sympathomimetic and sympatholytic drugs Relate the consequences of nicotine abuse with respect to autonomic control of the cardiovascular system An important way to understand the effects of native neurochemicals in the autonomic system is in considering the effects of pharmaceutical drugs. This can be considered in terms of how drugs change autonomic function. These effects will primarily be based on how drugs act at the receptors of the autonomic system neurochemistry. The signaling molecules of the nervous system interact with proteins in the cell membranes of various target cells. In fact, no effect can be attributed to just the signaling molecules themselves without considering the receptors. A chemical that the body produces to interact with those receptors is called an endogenous chemical , whereas a chemical introduced to the system from outside is an exogenous chemical . Exogenous chemicals may be of a natural origin, such as a plant extract, or they may be synthetically produced in a pharmaceutical laboratory. Broad Autonomic Effects One important drug that affects the autonomic system broadly is not a pharmaceutical therapeutic agent associated with the system. This drug is nicotine. The effects of nicotine on the autonomic nervous system are important in considering the role smoking can play in health. All ganglionic neurons of the autonomic system, in both sympathetic and parasympathetic ganglia, are activated by ACh released from preganglionic fibers. The ACh receptors on these neurons are of the nicotinic type, meaning that they are ligand-gated ion channels. When the neurotransmitter released from the preganglionic fiber binds to the receptor protein, a channel opens to allow positive ions to cross the cell membrane. The result is depolarization of the ganglia. Nicotine acts as an ACh analog at these synapses, so when someone takes in the drug, it binds to these ACh receptors and activates the ganglionic neurons, causing them to depolarize. Ganglia of both divisions are activated equally by the drug. For many target organs in the body, this results in no net change. The competing inputs to the system cancel each other out and nothing significant happens. For example, the sympathetic system will cause sphincters in the digestive tract to contract, limiting digestive propulsion, but the parasympathetic system will cause the contraction of other muscles in the digestive tract, which will try to push the contents of the digestive system along. The end result is that the food does not really move along and the digestive system has not appreciably changed. The system in which this can be problematic is in the cardiovascular system, which is why smoking is a risk factor for cardiovascular disease. First, there is no significant parasympathetic regulation of blood pressure. Only a limited number of blood vessels are affected by parasympathetic input, so nicotine will preferentially cause the vascular tone to become more sympathetic, which means blood pressure will be increased. Second, the autonomic control of the heart is special. Unlike skeletal or smooth muscles, cardiac muscle is intrinsically active, meaning that it generates its own action potentials. The autonomic system does not cause the heart to beat, it just speeds it up (sympathetic) or slows it down (parasympathetic). The mechanisms for this are not mutually exclusive, so the heart receives conflicting signals, and the rhythm of the heart can be affected ( Figure 15.13 ). Sympathetic Effect The neurochemistry of the sympathetic system is based on the adrenergic system. Norepinephrine and epinephrine influence target effectors by binding to the α-adrenergic or β-adrenergic receptors. Drugs that affect the sympathetic system affect these chemical systems. The drugs can be classified by whether they enhance the functions of the sympathetic system or interrupt those functions. A drug that enhances adrenergic function is known as a sympathomimetic drug , whereas a drug that interrupts adrenergic function is a sympatholytic drug . Sympathomimetic Drugs When the sympathetic system is not functioning correctly or the body is in a state of homeostatic imbalance, these drugs act at postganglionic terminals and synapses in the sympathetic efferent pathway. These drugs either bind to particular adrenergic receptors and mimic norepinephrine at the synapses between sympathetic postganglionic fibers and their targets, or they increase the production and release of norepinephrine from postganglionic fibers. Also, to increase the effectiveness of adrenergic chemicals released from the fibers, some of these drugs may block the removal or reuptake of the neurotransmitter from the synapse. A common sympathomimetic drug is phenylephrine, which is a common component of decongestants. It can also be used to dilate the pupil and to raise blood pressure. Phenylephrine is known as an α 1 -adrenergic agonist , meaning that it binds to a specific adrenergic receptor, stimulating a response. In this role, phenylephrine will bind to the adrenergic receptors in bronchioles of the lungs and cause them to dilate. By opening these structures, accumulated mucus can be cleared out of the lower respiratory tract. Phenylephrine is often paired with other pharmaceuticals, such as analgesics, as in the “sinus” version of many over-the-counter drugs, such as Tylenol Sinus ® or Excedrin Sinus ® , or in expectorants for chest congestion such as in Robitussin CF ® . A related molecule, called pseudoephedrine, was much more commonly used in these applications than was phenylephrine, until the molecule became useful in the illicit production of amphetamines. Phenylephrine is not as effective as a drug because it can be partially broken down in the digestive tract before it is ever absorbed. Like the adrenergic agents, phenylephrine is effective in dilating the pupil, known as mydriasis ( Figure 15.14 ). Phenylephrine is used during an eye exam in an ophthalmologist’s or optometrist’s office for this purpose. It can also be used to increase blood pressure in situations in which cardiac function is compromised, such as under anesthesia or during septic shock. Other drugs that enhance adrenergic function are not associated with therapeutic uses, but affect the functions of the sympathetic system in a similar fashion. Cocaine primarily interferes with the uptake of dopamine at the synapse and can also increase adrenergic function. Caffeine is an antagonist to a different neurotransmitter receptor, called the adenosine receptor. Adenosine will suppress adrenergic activity, specifically the release of norepinephrine at synapses, so caffeine indirectly increases adrenergic activity. There is some evidence that caffeine can aid in the therapeutic use of drugs, perhaps by potentiating (increasing) sympathetic function, as is suggested by the inclusion of caffeine in over-the-counter analgesics such as Excedrin ® . Sympatholytic Drugs Drugs that interfere with sympathetic function are referred to as sympatholytic, or sympathoplegic, drugs. They primarily work as an antagonist to the adrenergic receptors. They block the ability of norepinephrine or epinephrine to bind to the receptors so that the effect is “cut” or “takes a blow,” to refer to the endings “-lytic” and “-plegic,” respectively. The various drugs of this class will be specific to α-adrenergic or β-adrenergic receptors, or to their receptor subtypes. Possibly the most familiar type of sympatholytic drug are the β-blockers. These drugs are often used to treat cardiovascular disease because they block the β-receptors associated with vasoconstriction and cardioacceleration. By allowing blood vessels to dilate, or keeping heart rate from increasing, these drugs can improve cardiac function in a compromised system, such as for a person with congestive heart failure or who has previously suffered a heart attack. A couple of common versions of β-blockers are metoprolol, which specifically blocks the β 1 -receptor, and propanolol, which nonspecifically blocks β-receptors. There are other drugs that are α-blockers and can affect the sympathetic system in a similar way. Other uses for sympatholytic drugs are as antianxiety medications. A common example of this is clonidine, which is an α-agonist. The sympathetic system is tied to anxiety to the point that the sympathetic response can be referred to as “fight, flight, or fright.” Clonidine is used for other treatments aside from hypertension and anxiety, including pain conditions and attention deficit hyperactivity disorder. Parasympathetic Effects Drugs affecting parasympathetic functions can be classified into those that increase or decrease activity at postganglionic terminals. Parasympathetic postganglionic fibers release ACh, and the receptors on the targets are muscarinic receptors. There are several types of muscarinic receptors, M1–M5, but the drugs are not usually specific to the specific types. Parasympathetic drugs can be either muscarinic agonists or antagonists, or have indirect effects on the cholinergic system. Drugs that enhance cholinergic effects are called parasympathomimetic drugs , whereas those that inhibit cholinergic effects are referred to as anticholinergic drugs . Pilocarpine is a nonspecific muscarinic agonist commonly used to treat disorders of the eye. It reverses mydriasis, such as is caused by phenylephrine, and can be administered after an eye exam. Along with constricting the pupil through the smooth muscle of the iris, pilocarpine will also cause the ciliary muscle to contract. This will open perforations at the base of the cornea, allowing for the drainage of aqueous humor from the anterior compartment of the eye and, therefore, reducing intraocular pressure related to glaucoma. Atropine and scopolamine are part of a class of muscarinic antagonists that come from the Atropa genus of plants that include belladonna or deadly nightshade ( Figure 15.15 ). The name of one of these plants, belladonna, refers to the fact that extracts from this plant were used cosmetically for dilating the pupil. The active chemicals from this plant block the muscarinic receptors in the iris and allow the pupil to dilate, which is considered attractive because it makes the eyes appear larger. Humans are instinctively attracted to anything with larger eyes, which comes from the fact that the ratio of eye-to-head size is different in infants (or baby animals) and can elicit an emotional response. The cosmetic use of belladonna extract was essentially acting on this response. Atropine is no longer used in this cosmetic capacity for reasons related to the other name for the plant, which is deadly nightshade. Suppression of parasympathetic function, especially when it becomes systemic, can be fatal. Autonomic regulation is disrupted and anticholinergic symptoms develop. The berries of this plant are highly toxic, but can be mistaken for other berries. The antidote for atropine or scopolamine poisoning is pilocarpine. Sympathetic and Parasympathetic Effects of Different Drug Types Drug type Example(s) Sympathetic effect Parasympathetic effect Overall result Nicotinic agonists Nicotine Mimic ACh at preganglionic synapses, causing activation of postganglionic fibers and the release of norepinephrine onto the target organ Mimic ACh at preganglionic synapses, causing activation of postganglionic fibers and the release of ACh onto the target organ Most conflicting signals cancel each other out, but cardiovascular system is susceptible to hypertension and arrhythmias Sympathomimetic drugs Phenylephrine Bind to adrenergic receptors or mimics sympathetic action in some other way No effect Increase sympathetic tone Sympatholytic drugs β-blockers such as propanolol or metoprolol; α-agonists such as clonidine Block binding to adrenergic drug or decrease adrenergic signals No effect Increase parasympathetic tone Parasymphatho-mimetics/muscarinic agonists Pilocarpine No effect, except on sweat glands Bind to muscarinic receptor, similar to ACh Increase parasympathetic tone Anticholinergics/muscarinic antagonists Atropine, scopolamine, dimenhydrinate No effect Block muscarinic receptors and parasympathetic function Increase sympathetic tone Table 15.2 Disorders of the... Autonomic Nervous System Approximately 33 percent of people experience a mild problem with motion sickness, whereas up to 66 percent experience motion sickness under extreme conditions, such as being on a tossing boat with no view of the horizon. Connections between regions in the brain stem and the autonomic system result in the symptoms of nausea, cold sweats, and vomiting. The part of the brain responsible for vomiting, or emesis, is known as the area postrema. It is located next to the fourth ventricle and is not restricted by the blood–brain barrier, which allows it to respond to chemicals in the bloodstream—namely, toxins that will stimulate emesis. There are significant connections between this area, the solitary nucleus, and the dorsal motor nucleus of the vagus nerve. These autonomic system and nuclei connections are associated with the symptoms of motion sickness. Motion sickness is the result of conflicting information from the visual and vestibular systems. If motion is perceived by the visual system without the complementary vestibular stimuli, or through vestibular stimuli without visual confirmation, the brain stimulates emesis and the associated symptoms. The area postrema, by itself, appears to be able to stimulate emesis in response to toxins in the blood, but it is also connected to the autonomic system and can trigger a similar response to motion. Autonomic drugs are used to combat motion sickness. Though it is often described as a dangerous and deadly drug, scopolamine is used to treat motion sickness. A popular treatment for motion sickness is the transdermal scopolamine patch. Scopolamine is one of the substances derived from the Atropa genus along with atropine. At higher doses, those substances are thought to be poisonous and can lead to an extreme sympathetic syndrome. However, the transdermal patch regulates the release of the drug, and the concentration is kept very low so that the dangers are avoided. For those who are concerned about using “The Most Dangerous Drug,” as some websites will call it, antihistamines such as dimenhydrinate (Dramamine ® ) can be used. Interactive Link Watch this video to learn about the side effects of 3-D movies. As discussed in this video, movies that are shot in 3-D can cause motion sickness, which elicits the autonomic symptoms of nausea and sweating. The disconnection between the perceived motion on the screen and the lack of any change in equilibrium stimulates these symptoms. Why do you think sitting close to the screen or right in the middle of the theater makes motion sickness during a 3-D movie worse?
business_ethics
Summary 3.1 Adopting a Stakeholder Orientation An organization has duties and responsibilities with regard to each stakeholder; however, the implicit social contract between business and society means that meeting legal requirements might support only minimal ethical standards. Society on the whole and in the long run requires that business consider a broader range of duties in its relationships with key stakeholders. 3.2 Weighing Stakeholder Claims There are three approaches to stakeholder theory: the descriptive approach, the instrumental approach, and the normative approach. The normative approach takes the most comprehensive view of the organization and its stakeholders and is the fundamental basis of stakeholder theory. Organizations can analyze stakeholder claims by classifying them on the basis of their intensity and impact on the firm, as well as on the basis of their relationship to the firm. Such classifications may include enabling stakeholders, normative stakeholders, functional stakeholders, and diffused stakeholders. Using the lens of the four “publics” (the nonpublic, the latent, the aware, and the active), we can also understand a stakeholder claim on the basis of the public’s degree of awareness of a problem and ability to do something about it. 3.3 Ethical Decision-Making and Prioritizing Stakeholders Business leaders prioritize those stakeholders who have immediate needs or high urgency or great significance to the organization, and the identity of these groups may shift over time. Stakeholders can also be prioritized on the basis of their relationship to the organization using a matrix of their power and interest. Steps in the MITRE stakeholder management process are to establish trust, identify stakeholders, gather and analyze appropriate data, present information to management, and let stakeholders know they matter. Because customers are often considered high-priority stakeholders, it can be essential for corporations and nonprofit organizations to manage any expectations that customers (or donors) may have. 3.4 Corporate Social Responsibility (CSR) Most organizations must practice genuine corporate social responsibility to be successful in the modern marketplace. The triple bottom line places people and the planet on equal standing with profit in the mission of an organization. The genuine practice of CSR, unlike greenwashing, requires a commitment to an additional stakeholder, the planet, whose continued healthy existence is essential for any organization to operate.
Chapter Outline 3.1 Adopting a Stakeholder Orientation 3.2 Weighing Stakeholder Claims 3.3 Ethical Decision-Making and Prioritizing Stakeholders 3.4 Corporate Social Responsibility (CSR) Introduction In May 2018, in the wake of a global uproar after two Black men in a Philadelphia Starbucks were arrested while awaiting a friend, Starbucks closed its approximately eight thousand U.S. stores to conduct racial bias training ( Figure 3.1 ). 1 The company also officially changed its policy to allow people to visit its stores and restrooms without making a purchase, hoping to avoid more incidents like this one (sparked by a White employee calling 9-1-1 when the men did not buy anything). The two men who were arrested eventually settled with Starbucks for an undisclosed sum. As one of the largest beverage retailers in the world, Starbucks directly affects countless stakeholders: food and drink distributors; coffee and tea growers; milk producers; urban and suburban communities; local, state, and national governments; more than 300,000 employees and 1,600 institutional investors; and millions of customers. 2 The company’s decision to close its U.S. stores for half a day was financially costly, and the training session could never fully solve the problem of conscious or unconscious bias. But the firm believed it was the right thing to do. Why does it matter to its stakeholders what Starbucks does? What role do stakeholders play in a company’s decisions about its ethical behavior, and why?
[ { "answer": { "ans_choice": 3, "ans_text": "D" }, "bloom": null, "hl_context": "<hl> When a product does not live up to its maker ’ s claims for whatever reason , the manufacturer needs to correct the problem to retain or regain customers ’ trust . <hl> <hl> Without this trust , the interdependence between the company and its stakeholders can fail . <hl> By choosing to recognize and repay its customer stakeholders , Samsung acted at an ethical maximum , taking the strongest possible action to behave ethically in a given situation . An ethical minimum , or the least a company might do that complies with the law , would have been to offer the warning and nothing more . This may have been a defensible position in court , but the warning might not have reached all purchasers of the defective machine and many children could have been hurt . Samsung , based in South Korea , is a large , multinational corporation that makes a variety of products , including household appliances such as washers and dryers . When Samsung ’ s washers developed a problem with the spin cycle in 2017 , the company warned customers that the machines could become unbalanced and tip over , and that children should be kept away . The problem persisted , however , and Samsung ’ s responsibility and legal exposure increased . The eventual fix was to offer all owners of the particular washer model a full refund even if the customer did not have a complaint , and to offer free pick up of the machine as well . The recall covered almost three million washers , which ranged in price from $ 450 to $ 1500 . By choosing to spend billions to rectify the problem , Samsung limited its legal exposure to potential lawsuits , settlement of which would likely have far exceeded the refunds it paid . <hl> This example demonstrates the weight of the implicit social contract between a company and its stakeholders and the potential impact on the bottom line if that contract is broken . <hl>", "hl_sentences": "When a product does not live up to its maker ’ s claims for whatever reason , the manufacturer needs to correct the problem to retain or regain customers ’ trust . Without this trust , the interdependence between the company and its stakeholders can fail . This example demonstrates the weight of the implicit social contract between a company and its stakeholders and the potential impact on the bottom line if that contract is broken .", "question": { "cloze_format": "Maintaining trust between stakeholders and organizations is ________.", "normal_format": "What is maintaining trust between stakeholders and organizations?", "question_choices": [ "the stakeholder’s responsibility", "an ethical minimum", "an ethical maximum", "a social contract" ], "question_id": "fs-idm364200496", "question_text": "Maintaining trust between stakeholders and organizations is ________." }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 0, "ans_text": "A" }, "bloom": null, "hl_context": "<hl> Essential to Stout ’ s point is that shareholders do not necessarily behave as a class . <hl> <hl> Some will want to maximize their investment even at a cost to other stakeholders . <hl> Some may want to extend beyond the legal minimum and seek a long-term perspective on profit maximization , demanding better treatment of stakeholders to maximize future potential value and to do more good than harm .", "hl_sentences": "Essential to Stout ’ s point is that shareholders do not necessarily behave as a class . Some will want to maximize their investment even at a cost to other stakeholders .", "question": { "cloze_format": "A shareholder is a stakeholder who ________.", "normal_format": "Which of the following is correct about a shareholder that is a stakeholder?", "question_choices": [ "holds stock for investment", "has a general interest in the fate of all publicly traded companies", "focuses on the means by which firms get their products to market", "always purchases the product or service of a particular company" ], "question_id": "fs-idm208658784", "question_text": "A shareholder is a stakeholder who ________." }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 2, "ans_text": "C" }, "bloom": null, "hl_context": "If we carry the idea of stakeholder to the extreme , every person is a stakeholder of every company . <hl> The first step in stakeholder management , the process of accurately assessing stakeholder claims so an organization can manage them effectively , is therefore to define and prioritize stakeholders significant to the firm . <hl> <hl> Then , it must consider their claims . <hl> <hl> A challenge for business leaders is to assign appropriate weights to stakeholder claims on their companies in an ethical manner . <hl> This task is even more difficult because a claim is not necessarily a formal process . “ Essentially , stakeholders ‘ want something ’ from an organization . Some want . . . to influence what the organization does . . . and others are , or potentially could be , concerned with the way they are affected by the organization . ” 15", "hl_sentences": "The first step in stakeholder management , the process of accurately assessing stakeholder claims so an organization can manage them effectively , is therefore to define and prioritize stakeholders significant to the firm . Then , it must consider their claims . A challenge for business leaders is to assign appropriate weights to stakeholder claims on their companies in an ethical manner .", "question": { "cloze_format": "A stakeholder claim ________.", "normal_format": "What is a stakeholder claim?", "question_choices": [ "is usually a complaint", "is always financial", "is any matter of concern for the corporation or company", "is the same as a lawsuit" ], "question_id": "fs-idm232732272", "question_text": "A stakeholder claim ________." }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 2, "ans_text": "C" }, "bloom": null, "hl_context": "<hl> Overall , MITRE stresses that an organization must sustain trust with its stakeholders through communication efforts . <hl> <hl> To accomplish this , however , stakeholders must first be clearly identified and then periodically reidentified , because stakeholder cohorts change in size and significance over time . <hl> <hl> The concerns or claims of stakeholders are identified through data gathering and analysis . <hl> Sometimes a firm will conduct surveys or focus groups with customers , suppliers , or other stakeholders . Other times , product usage data will be available as a function of sales figures and marketing data . For software in web and mobile applications , for example , user data may be readily available to show how stakeholders are using the company ’ s digital services or why they appear to be purchasing its products . Another source of stakeholder data is social media , where firms can monitor topics stakeholders of all types are talking about . What matters is gathering relevant and accurate data and ensuring that key stakeholders are providing it . <hl> In the next step , managers present the results of their research to the company ’ s decision makers or make decisions themselves . <hl> <hl> 19 Finally , stakeholders should be informed that their concerns were taken into consideration and that the company will continue to heed them . <hl> <hl> In other words , the firm should convey to them that they are important . <hl>", "hl_sentences": "Overall , MITRE stresses that an organization must sustain trust with its stakeholders through communication efforts . To accomplish this , however , stakeholders must first be clearly identified and then periodically reidentified , because stakeholder cohorts change in size and significance over time . The concerns or claims of stakeholders are identified through data gathering and analysis . In the next step , managers present the results of their research to the company ’ s decision makers or make decisions themselves . 19 Finally , stakeholders should be informed that their concerns were taken into consideration and that the company will continue to heed them . In other words , the firm should convey to them that they are important .", "question": { "cloze_format": "In correct order, the stakeholder management steps adapted from the approach of the MITRE consulting firm are to ________.", "normal_format": "In correct order, the stakeholder management steps adapted from the approach of the MITRE consulting firm are to which of the following?", "question_choices": [ "build trust, identify stakeholders, prioritize claims, visualize changes, and perform triage", "build trust, identify stakeholders, gather and analyze data, present results, make changes, and prepare a communication strategy", "build trust, identify stakeholders, gather and analyze data, present findings to management, and communicate key messages to stakeholders conveying the company’s appreciation of them", "identify stakeholders, gather and analyze data, make changes, and present results" ], "question_id": "fs-idm337094208", "question_text": "In correct order, the stakeholder management steps adapted from the approach of the MITRE consulting firm are to ________." }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 2, "ans_text": "C" }, "bloom": null, "hl_context": "Corporations have responded to stakeholder concerns about the environment and sustainability . In 1999 , Dow Jones began publishing an annual list of companies for which sustainability was important . Sustainability is the practice of preserving resources and operating in a way that is ecologically responsible in the long term . <hl> 24 The Dow Jones Sustainability Indices “ serve as benchmarks for investors who integrate sustainability considerations into their portfolios . ” 25 There is a growing awareness that human actions can , and do , harm the environment . <hl> Destruction of the environment can ultimately lead to reduction of resources , declining business opportunities , and lowered quality of life . Enlightened business stakeholders realize that profit is only one positive effect of business operations . In addition to safeguarding the environment , other ethical contributions that stakeholders could lobby corporate management to make include establishing schools and health clinics in impoverished neighborhoods and endowing worthwhile philanthropies in the communities where companies have a presence .", "hl_sentences": "24 The Dow Jones Sustainability Indices “ serve as benchmarks for investors who integrate sustainability considerations into their portfolios . ” 25 There is a growing awareness that human actions can , and do , harm the environment .", "question": { "cloze_format": "The Dow Jones Sustainability Indices provides information for ________.", "normal_format": "For whom do the Dow Jones Sustainability Indices provide information?", "question_choices": [ "investors who seek quick profit", "investors who seek long-term returns", "investors who value CSR in companies", "marketing promotions of each of its members" ], "question_id": "fs-idm233245152", "question_text": "The Dow Jones Sustainability Indices provides information for ________." }, "references_are_paraphrase": 0 } ]
3
3.1 Adopting a Stakeholder Orientation Learning Objectives By the end of this section, you will be able to: Identify key types of business-stakeholder relationships Explain why laws do not dictate every ethical responsibility a company may owe key stakeholders Discuss why stakeholders’ welfare must be at the heart of ethical business decisions Have you ever had a stake in a decision someone else was making? Depending on your relationship with that person and your level of interest in the decision, you may have tried to ensure that the choice made was in your best interests. Understanding your somewhat analogous role as a stakeholder in businesses large and small, local and global, will help you realize the value of prioritizing stakeholders in your own professional life and business decisions. Stakeholder Relationships Many individuals and groups inside and outside a business have an interest in the way it brings products or services to market to turn a profit. These stakeholders include customers, clients, employees, shareholders, communities, the environment, the government, and the media (traditional and social), among others. All stakeholders should be considered essential to a business, but not all have equal priority. Different groups of stakeholders carry different weights with decision makers in companies and assert varying levels of interest and influence. As we examine their roles, consider how an organization benefits by working with its stakeholders and how it may benefit from encouraging stakeholders to work together to promote their mutual interests. What are the roles of an organization’s many stakeholders? We begin with the internal stakeholders. The board of directors—in a company large enough to have one—is responsible for defining and evaluating the ongoing mission of a business after its founding. It broadly oversees decisions about the mission and direction of the business, the products or services offered, the markets in which the business will operate, and salary and benefits for the senior officers of the organization. The board also sets goals for income and profitability. Its most important function is to select and hire the chief executive officer (CEO) or president. The CEO is usually the only employee who reports directly to the board of directors, and he or she is charged with implementing the policies the board sets and consulting with them on significant issues pertaining to the company, such as a dramatic shift in products or services offered or discussions to acquire—or be acquired by—another firm. In turn, the CEO hires executives to lead initiatives and carry out procedures in the various functional areas of the business, such as finance, sales and marketing, public relations, manufacturing, quality control, human resources (sometimes called human capital), accounting, and legal compliance. Employees in these areas are internal stakeholders in the success of both their division and the larger corporation. Some interact with the outside environment in which the business operates and serve as contact points for external stakeholders, such as media and government, as well. In terms of external stakeholders for a business, customers certainly are an essential group. They need to be able to trust that products and services are backed by the integrity of the company. They also provide reviews, positive or negative, and referrals. Customers’ perceptions of the business matter, too. Those who learn that a business is not treating employees fairly, for instance, may reconsider their loyalty or even boycott the business to try to influence change in the organization. Stakeholder relationships, good and bad, can have compound effects, particularly when social media can spread word of unethical behavior quickly and widely. Key external stakeholders are usually those outside of the organization who most directly influence a business’s bottom line and hold power over the business. Besides customers and clients, suppliers have a great deal of influence and command a great deal of attention from businesses of all sizes. Governments hold power through regulatory bodies, from federal agencies such as the Environmental Protection Agency to the local planning and zoning boards of the communities in which businesses exist. These latter groups often exercise influence over the physical spaces where businesses work and try to grow ( Figure 3.2 ). Businesses are responsible to their stakeholders. Every purchase of a product or a service carries with it a sort of promise. Buyers promise that their money or credit is good, and businesses promise a level of quality that will deliver what is advertised. The relationship can quickly get more complex, though. Stakeholders also may demand that the businesses they patronize give back to the local community or protect the global environment while developing their products or providing services. Employees may demand a certain level of remuneration for their work. Governments demand that companies comply with laws, and buyers in business-to-business exchanges (B2B, in business jargon) demand not only high-quality products and services but on-time delivery and responsive maintenance and service should something go wrong. Meeting core obligations to stakeholders is primarily about delivering good products and services, but it is also about communicating and preparing for potential problems, whether from within the company or from external circumstances like a natural disaster. Ethical Responsibilities Often Extend Beyond Legal Requirements We have seen that stakeholders include the people and entities invested in and influential in the success of an organization. It is also true that stakeholders can have multiple, and simultaneous, roles. For example, an employee can also be a customer and a stockholder. Any transaction between a stakeholder and a business organization may appear finite. For instance, after you purchase something from a store you leave and go home. But your relationship with the store probably continues. You might want to repurchase the item or ask a question about a warranty. The store may have collected future marketing data about you and your purchases through its customer loyalty program or your use of a credit card. Samsung, based in South Korea, is a large, multinational corporation that makes a variety of products, including household appliances such as washers and dryers. When Samsung’s washers developed a problem with the spin cycle in 2017, the company warned customers that the machines could become unbalanced and tip over, and that children should be kept away. The problem persisted, however, and Samsung’s responsibility and legal exposure increased. The eventual fix was to offer all owners of the particular washer model a full refund even if the customer did not have a complaint, and to offer free pick up of the machine as well. The recall covered almost three million washers, which ranged in price from $450 to $1500. By choosing to spend billions to rectify the problem, Samsung limited its legal exposure to potential lawsuits, settlement of which would likely have far exceeded the refunds it paid. This example demonstrates the weight of the implicit social contract between a company and its stakeholders and the potential impact on the bottom line if that contract is broken. When a product does not live up to its maker’s claims for whatever reason, the manufacturer needs to correct the problem to retain or regain customers’ trust. Without this trust, the interdependence between the company and its stakeholders can fail. By choosing to recognize and repay its customer stakeholders, Samsung acted at an ethical maximum , taking the strongest possible action to behave ethically in a given situation. An ethical minimum , or the least a company might do that complies with the law, would have been to offer the warning and nothing more. This may have been a defensible position in court, but the warning might not have reached all purchasers of the defective machine and many children could have been hurt. Each case of a faulty product or poorly delivered service is different. If laws reach above a minimum standard, they can grow cumbersome and impede business growth. If businesses adhere only to laws and ethical minimums, however, they can develop poor reputations and people can be harmed. The ethically minimal course of action is not illegal or necessarily unethical, but the company choosing it will have failed to recognize the value of its customers. Cases from the Real World Amazon Sets a Demanding Pace on the Job In a visit to an Amazon distribution center, a group of business students and their professors met with the general manager. 3 After taking them on an extensive tour of the five-acre facility, the general manager commented on the slowness of the visitors’ walking pace. He described the Amazon Pace, a fast, aggressive walk, and confirmed that the average employee walks eight or nine miles during a shift. These employees are called “pickers,” and their task is to fill an order and deliver it to the processing and packing center as quickly as possible. The design of the center is a trade secret that results in a random distribution of products. Therefore, the picker has to cover a number of directions and distances while filling an order. Those who cannot keep up the pace are usually let go, just as would be those who steal. Critical Thinking Does the requirement to walk an average of eight or nine miles at a fast pace every day strike you as a reasonable expectation for employees at Amazon, or any other workplace? Why or why not? Should a company that wants to impose this requirement tell job applicants beforehand? Is it ethical for customers to patronize a company that imposes this kind of requirement on its employees? And if not, what other choices do customers have and what can they do about it? The center’s general manager may have been exaggerating about the Amazon Pace to impress upon his visitors how quickly and nimbly pickers fill customer orders for the company. If not, however, is such a pace sustainable without the risk of physiological and psychological stress? The law only partly captures the ethical obligations firms owe their stakeholders. One way many companies go beyond the legally required minimum as employers is to offer lavish amenities —that is, resources made available to employees in addition to wages, salary, and other standard benefits. They include such offerings as on-site exercise rooms and other services, company discounts, complimentary or subsidized snacks or meals, and the opportunity to buy stock in the company at a discounted price. Astute business leaders see the increased costs of amenities as an investment in retaining employees as long-term stakeholders. Stakeholder loyalty within and outside the firm is essential in sustaining any business venture, no matter how small or large. What Would You Do? The Social Responsibility of Business There are two opposing views about how businesses, and large publicly held corporations in particular, should approach ethics and social responsibility. One view holds that businesses should behave ethically within the marketplace but concern themselves only with serving shareholders and other investors. This view places economic considerations above all others. The other view is that stakeholders are not the means to the end (profit) but are ends in and of themselves as human beings (see our earlier discussion of deontological ethics in Ethics from Antiquity to the Present ). Thus, the social responsibility of business view is that being responsible to customers, employees, and a host of other stakeholders should be not only a corporate concern but central to a business’s mission. In essence, this view places a premium on the careful consideration of stakeholders. Consider what approach you might take if you were the CEO of a multinational corporation. Critical Thinking Would your business be driven primarily by a particular social mission or simply by economics? How do you think stakeholder relationships would influence your approach to business? Why? Link to Learning Read a detailed consideration of the social responsibility of business in the form of polite but fiercely oppositional correspondence between economist Milton Friedman and John Mackey, founder and CEO of Whole Foods to learn more. One challenge for any organization’s managers is that not all stakeholders agree on where the company should strive to land when it chooses between ethical minimums and maximums. Take stockholders, for example. Logically, most stockholders are interested in maximizing the return on their investment in the firm, which earns profit for them in the form of dividends. Lynn Stout, late Professor of Law at Cornell Law School, described the role of shareholder in this way: “Shareholders as a class want companies to be able to treat their stakeholders well, because this encourages employee and customer loyalty . . . Yet individual shareholders can profit from pushing boards to exploit committed stakeholders—say, by threatening to outsource jobs unless employees agree to lower wages, or refusing to support products customers have come to rely on unless they buy expensive new products as well. In the long run, such corporate opportunism makes it difficult for companies to attract employee and customer loyalty in the first place.” 4 Essential to Stout’s point is that shareholders do not necessarily behave as a class. Some will want to maximize their investment even at a cost to other stakeholders. Some may want to extend beyond the legal minimum and seek a long-term perspective on profit maximization, demanding better treatment of stakeholders to maximize future potential value and to do more good than harm. In the long run, stakeholder welfare must be kept at the heart of each company’s business operations for these significant, twin reasons: It is the right thing to do and it is good for business. Still, if managers need additional incentive to act on the basis of policies that benefit stakeholders, it is useful to recall that stakeholders who believe their interests have been ignored will readily make their displeasure known, both to company management and to the much wider community of social media. 3.2 Weighing Stakeholder Claims Learning Objectives By the end of this section, you will be able to: Explain why stakeholders’ claims vary in importance Categorize stakeholders to better understand their claims As we saw earlier in this chapter and in Why Ethics Matter , the law only partially captures the ethical obligations firms owe their stakeholder s. A particular stakeholder claim , that is, any given stakeholder’s interest in a business decision, may therefore challenge the ethical stance even of an organization that complies with the law. For example, some community members may oppose the opening of a “big box” chain store that threatens the livelihoods of small-business owners in the area, while shareholders, creditors, employees, and consumers within the nearby neighborhoods support it as an additional opportunity for profit and quality goods at competitive prices. Conflicts like this illustrate how complicated prioritizing stakeholder claims can be, particularly when there are ethical pros and cons on both sides. A big box store may offer a wider selection of goods at lower prices, for example, and create jobs for teens and part-time workers. A related theme to recall is that even though all stakeholder claims are important for a company to acknowledge, not all claims are of equal importance. Most business leaders appreciate that a company’s key stakeholders are essential to its efficient operation and growth, and that its overall mission, goals, and limited resources will force its managers to make choices by prioritizing stakeholders’ needs. In this section, we look at ethical ways in which business managers can begin to make those decisions. The Ethical Basis of Stakeholders’ Claims Stakeholder claims vary in their significance for a firm. According to Donaldson and Preston, 5 there are three theoretical approaches to considering stakeholder claims: a descriptive approach, an instrumental approach, and a normative approach. The descriptive approach sees the company as composed of various stakeholder groups, each with its own interests. These interests impinge on the company to a greater or lesser degree; thus, the main point of the descriptive approach is to develop the most accurate model and act on it in ways that weigh and balance these interests as fairly as possible. The instrumental approach connects stakeholder management and financial outcomes, proposing that appropriate management of stakeholder interests is important and useful because it contributes to a positive bottom line. The normative approach considers stakeholders as ends in themselves rather than simply as means to achieve better financial results. According to Donaldson and Preston, in the normative approach “the interests of all stakeholders are of intrinsic value. That is, each group of stakeholders merits consideration for its own sake and not merely because of its ability to further the interests of some other group, such as the shareowners.” 6 This approach is the one that most appropriately represents ethical stakeholder theory, according to Donaldson and Preston, and it places an objective consideration of all stakeholders’ interests ahead of fiscal considerations alone. We can also view these three approaches to stakeholders as occupying levels of increasing comprehensiveness. At the lowest level is the descriptive approach, which merely sets the stage for consideration of stakeholder claims and concerns. The instrumental aspect combines a consideration for profit along with other stakeholder concerns and attempts to balance these interests with particular attention to the way the company and its shareholders might be affected. The normative approach takes the most comprehensive view of the organization and its stakeholders, putting the focus squarely on stakeholders. Although Donaldson and Preston stress that the descriptive and instrumental approaches are integral to stakeholder theory, they contend that the fundamental basis of stakeholder theory is normative. 7 Of course, these are theoretical approaches, and the extent to which any of them is implemented in a given company will vary. But unfortunately, the decision to disconnect from stakeholders is both real and expensive for a corporation. A 2005 survey of customers of 362 companies is demonstrative: “Only 8% of customers described their experience as ‘superior.’ However, 80% of the companies surveyed believe that the experience they have been providing is indeed superior.” 8 Another study found significant links between levels of customer satisfaction and a firm’s performance, including rates of retention, overall revenue, and stock price. 9 Enlightened companies spend time and resources testing their stakeholders’ concerns and eliciting their feedback while there is time to incorporate it into management decisions. Link to Learning This article discusses a recent video showing United Airlines removing ticketed, seated passengers from a plane to make room for four of its employees who needed to fly to another airport igniting debate over company policies and how they are implemented. This related article about the United Airlines overbooking situation provides some more information. Upon being asked to deplane and take a later flight, should a customer who has booked the fare for the earlier flight have the right to refuse? Which stakeholder(s) do you think United valued more in this incident? Why? Airlines overbook to ensure that despite any no-shows or cancellations, any given flight will have as many occupied seats as possible, because an unoccupied seat represents lost revenue. In terms of valuing stakeholders, does this strategy make sense to you? Why or why not? A classic example of negative consumer reaction is the response that met Ford Motor Company’s 1958 introduction of the Edsel ( Figure 3.3 ). Ford had done extensive research to create a luxury family sedan aimed at an upper-income segment of the market then dominated by Buick, Oldsmobile, and Chrysler. However, the market did not identify Ford products with high status, and the Edsel did not last three years in the marketplace. Ford failed to serve the investors, suppliers, and employees who depended on the company for their livelihoods. Of course, the corporation survived that failure, perhaps because it learned the lessons of stakeholder management the hard way. Entertainers too (as well as their clubs, venues, and studios) are sensitive to the views of their stakeholders—that is, fans and the consuming public as a whole. Scarlett Johansson recently signed on to play the role of Dante “Tex” Gill in a biographical film (or “biopic”). Gill had been identified as female at birth but spent much of his professional career self-identifying as male. When the casting was announced in July 2018, it provoked a controversy among transgender rights groups, and within a few days, Johansson announced she had withdrawn from the role. 10 “In light of recent ethical questions raised surrounding my casting as Dante Tex Gill, I have decided to respectfully withdraw my participation in the project. . . . While I would have loved the opportunity to bring Dante’s story and transition to life, I understand why many feel he should be portrayed by a transgender person, and I am thankful that this casting debate, albeit controversial, has sparked a larger conversation about diversity and representation in film,” she said. 11 Defining Stakeholder Categories To better understand stakeholder theory and, ultimately, manage stakeholder claims and expectations, it may be helpful to take a closer look at categories of stakeholders. One way to categorize stakeholders is by defining their impact. For example, regulatory stakeholders including stockholders, legislatures, government regulators, and boards of directors are enabling stakeholder s because they permit the firm to function. Normative stakeholders such as competitors and peers influence the norms or informal rules of the industry; functional stakeholder s are those who influence inputs, such as suppliers, employees, and unions, and those influencing outputs such as customers, distributors, and retailers. Finally, diffused stakeholder s include other organizations such as nongovernmental organizations (NGOs), voters, and mass media organizations with less direct relationships but potential for meaningful impacts on firms ( Figure 3.4 ). 12 As the Figure 3.4 shows, enabling and functional stakeholders are those active in design, production, and marketing. They provide input for the products or services the organization distributes in the form of output. Companies should identify all the stakeholders shown in the figure and consider how they are linked to the firm. Although the diffused linkage stakeholders will vary according to place and time, the enabling, functional, and normative linkage stakeholders are constant, because they are integral to the operation of the firm. Stakeholders, in turn, can exert some control and authority by serving on the board of directors, by exercising their power as purchasers, by being elected to public office, or by joining employees’ unions. In many cases, if one stakeholder effects a change in the firm, other stakeholders will be affected. For example, if an NGO raises concerns about unequal pay of laborers on a rubber plantation that provides raw materials for gasket makers, the supplier may be forced to equalize pay, incurring additional expense. The supplier has taken the ethical action, but ultimately the cost is likely passed through the supply chain to the end user, the retail purchaser at the local car dealer. The supplier could also have absorbed the additional cost, diminishing the bottom line and reducing returns for stockholders, who may withdraw their investment from the company. Although this model of stakeholder relationships is complex, it is useful in understanding the impact of each individual group on the organization as a whole. James E. Grunig, now professor emeritus at University of Maryland, and Todd Hunt, who together developed the organizational linkage model in Figure 3.4 , looked at these relationships through the lens of four “publics” or cohorts: the nonpublic, the latent, the aware, and the active. These publics are distinguished by their degree of awareness of a problem and ability to do something about it. In the nonpublic cohort, no problem is recognized or exists. For the latent public, a problem is there but the public does not recognize it. The aware public recognizes that a problem exists. The active public is aware of the problem and organizes to respond to it. These categories help the organization design its message about a problem and decide how to communicate. Herein lies the ethical significance. If an organization is aware of a problem and the public is not, the organization has an opportunity to communicate and guide the public in recognizing and dealing with it, as the example of Johnson & Johnson’s Tylenol product in the following box illustrates. Cases from the Real World The Chicago Tylenol Murders In the fall of 1982, Johnson & Johnson faced a public relations nightmare when customers in Cook County, Illinois, began dying—eventually, a total of seven people died—after taking over-the-counter, Tylenol-branded acetaminophen capsules. Analysis showed the presence of potassium cyanide, a fatal poison in no way connected with the production of the pill. Johnson & Johnson voluntarily removed all Tylenol products from the U.S. marketplace and offered to pay full retail price for any pills returned to the company. This represented about thirty million bottles of capsules worth more than $100 million. (Significantly, too, Johnson & Johnson decided on this wide-ranging action despite the fact that it and law enforcement realized the cyanide poisoning was limited to Cook County, Illinois.) Because Tylenol was a flagship product bringing in significant revenue, this was an extreme action but one based on the company’s ethics, rooted in its corporate credo. Investigation showed that someone had tinkered with the bottles and injected cyanide into the product in stores. Although no one was ever apprehended, the entire drug industry responded, following Johnson & Johnson’s lead, by introducing tamper-proof containers that warned consumers not to use the product if the packaging appeared in any way compromised. The strong ethical stance taken by Johnson & Johnson executives resulted in immediate action that reassured the public. When the company eventually returned Tylenol to the market, it introduced it first to clinics, hospitals, and physicians’ offices, promoting medicine’s professional trust in the product. The strategy was successful. Before the poisonings, Tylenol had 37 percent of the market of over-the-counter analgesics. That plunged to 7 percent in fall 1982 but was resurrected to 30 percent by fall 1983. Critical Thinking In its corporate credo, Johnson & Johnson identifies multiple stakeholders: users of its products (output), employees (input), employees’ families (diffused linkage), and the government (enabling linkage). Applying Grunig and Hunt’s theory, do you believe Johnson & Johnson acted as an enlightened company that includes and communicates with a variety of publics? U.S. business leaders are often accused of acting on a short-term obsession with profitability at the expense of the long-term interests of their corporation. Which aspects of the Tylenol crisis demonstrate a short-term perspective? Which show the value of a longer-term perspective? Link to Learning With the adoption of its credo, Johnson & Johnson became one of the first corporations to create something like a mission statement. Read the Johnson & Johnson credo to learn more. On the other hand, a company might try to manage a problem by covering it up or denying it. For example, Volkswagen had data that showed its diesel engine’s emissions exceeded U.S. pollution standards. Rather than redesign the engine, Volkswagen engineers installed a unit in each car to interpret the emissions as if they met Environmental Protection Agency standards. When the fraud was discovered, Volkswagen was required to buy back millions of cars. As of September 2017, the company had incurred fines and expenses in excess of $30 billion, and some employees had gone to jail. Such damage is bad enough, but loss of reputation and the trust of consumers and stockholders has hurt the company’s value and share price. 13 Volkswagen’s management of stakeholder relationships was poor and extremely expensive. Once-loyal stakeholders became part of an aware and active public—a group of people united by a common problem and organized for satisfaction, sometimes demanding compensation. 14 A challenge for business leaders is to assign appropriate weights to stakeholder claims on their companies in an ethical manner. This task is even more difficult because a claim is not necessarily a formal process. “Essentially, stakeholders ‘want something’ from an organization. Some want . . . to influence what the organization does . . . and others are, or potentially could be, concerned with the way they are affected by the organization.” 15 If a stakeholder has its own identity or voice, or if members of a stakeholder group are many, the claim can be clear and direct, such as in the case of a union negotiating for better pay and benefits, or a community trying to lure a corporation to open operations there. Think of the enormous effort communities around the world make to try to get the Olympics or World Cup organizers to bring the competition to their locale. In spite of significant investment and debt, these communities see a real advantage to their local economy. Many stakeholder claims are indirect, or “voiceless,” due perhaps to their representing relatively few individuals relative to the size and power of the organization and the time required to evoke a response from a large, bureaucratic company. If you have ever had a problem with a cable television or satellite company, you can immediately understand this stakeholder relationship, because it is so difficult to find someone with enough authority to make a decision on behalf of the company. Some companies count on individuals’ growing frustrated and giving up on the claim. An indirect stakeholder claim might also be one that affects future generations, such as concerns about air and water pollution. For example, University of Southern California law professor Christopher D. Stone introduced in 1972 what was then a radical concept for the law in the United States, that the environment itself is entitled to legal standing in the courts. If this were so, then the environment might also be eligible for certain protections under the law. Appearing at the dawn of increasing social awareness of ecologic concerns, Stone’s influential law review article “Should Trees Have Standing?” gave many environmentalists a new legal philosophy to harness in defense of the natural world. 16 Link to Learning Try playing a game of stakeholder identification, mapping, and analysis, such as this one from the “Gamestorming” website to learn more. 3.3 Ethical Decision-Making and Prioritizing Stakeholders Learning Objectives By the end of this section, you will be able to: Identify the factors that affect stakeholder prioritization Explain why priorities will vary based upon the interest and power of the stakeholder Describe how to prioritize stakeholder claims, particularly when they conflict If we carry the idea of stakeholder to the extreme, every person is a stakeholder of every company. The first step in stakeholder management , the process of accurately assessing stakeholder claims so an organization can manage them effectively, is therefore to define and prioritize stakeholders significant to the firm. Then, it must consider their claims. Given that there are numerous types of stakeholders, how do managers balance these claims? Ethically, no group should be treated better than another, and managers should respond to as many stakeholders as possible. However, time and resource limitations require organizations to prioritize claims as stakeholder needs rise and fall. Stakeholder Prioritization First, it may help to speak to the expectations that any stakeholders may have of a particular business or institution. It depends on particular stakeholders, of course, but we can safely say that all stakeholders expect a form of satisfaction from an organization. If these stakeholders are shareholders (stockowners), then they generally wish to see a high return on their purchase of company shares. If, on the other hand, they are employees, they typically hope for interesting tasks, a safe work environment, job security, and rewarding pay and benefits. If, yet again, the stakeholders are members of the community surrounding a business, they usually wish that the company not harm the physical environment or degrade the quality of life within it. So the task confronting an organization’s management begins with understanding these multiple and sometimes conflicting expectations and ethically deciding which stakeholders to focus on and in what sequence, if not all stakeholders cannot be addressed simultaneously, that is, stakeholder prioritization . It helps to actively gather information about all key stakeholders and their claims. First, managers must establish that an individual with a concern is a member of a stakeholder group. For example, a brand may attract hundreds or thousands of mentions on Twitter each day. Which ones should be taken seriously as representative of key stakeholders? Brand managers look for patterns of communication and for context when deciding whether to engage with customers in the open expanses of social media platforms. Link to Learning Read this article “Five Questions to Identify Key Stakeholders” in the Harvard Business Review to learn more about identifying your key stakeholders. After establishing that a key stakeholder group is being represented, the manager should identify what the company needs from the stakeholder. This simply helps clarify the relationship. If nothing is needed immediately or for the foreseeable future, this does not mean the stakeholder group does not matter, but it can be a good indication that the stakeholder need not be prioritized at the moment. Note that managers are often considering these questions in real time, usually with limited resources and power, and that circumstances can change in a matter of moments. In one sense, all representatives of a company are constantly practicing stakeholder prioritization. It need not be a formal process. At times, it is a question of which supplier should be praised or prodded or which customer has a larger order to fill or a special request that might be met. What matters is establishing that someone is a stakeholder, that the concern is currently important, and that the relationship matters for the growth of the business. If the firm cannot survive without this particular stakeholder or replace him or her relatively easily, then such a person should have priority over other stakeholders who do not meet this criterion. Key suppliers, lucrative or steady customers, and influential regulators must all be attended to but not necessarily capitulated to. For example, a local state legislator representing the district where a business is located may be urging the legislature to raise business taxes to generate more revenue for the state. By him- or herself, the legislator may not have sufficient political clout to persuade the legislature to raise taxes. Yet wise business leaders will not ignore such a representative and will engage in dialogue with him or her. The legislator may eventually be able to win others over to the cause, so it behooves perceptive management to establish a working relationship with him or her. Not every stakeholder can command constant attention, and no firm has unlimited time or resources, so in one sense, this prioritizing is simply the business of management. Combine the inherent priority of the stakeholder relationship with the level of exigency , that is, the level of urgency of a stakeholder claim, to arrive at a decision about where to begin focusing resources and efforts. Stakeholder prioritization will also vary based on time and circumstance. For example, a large retailer facing aggressive new competitors must prioritize customer service and value. With Amazon acquiring Whole Foods and drastically cutting prices, the grocery chain’s customer base may very well grow because prices could become more attractive while the perception of high quality may persist. Potential customers may no longer need to economize by shopping elsewhere. 17 Whole Foods’ competitors, on the other hand, must now prioritize customer service, whereas before they could compete on price alone. Whole Foods can become a serious competitor to discount grocery stores like ALDI and Walmart. Another way to prioritize stakeholder relationships is with a matrix of their power and interest. As Figure 3.5 shows, a stakeholder group can be weighted on the basis of its influence (or power) over and interest in its relationship to the firm. A stakeholder with a high level of both power and interest is a key stakeholder. If this type of stakeholder group encounters a problem, its priority rises. On the supplier side, a small farmer or seasonal supplier could fall in the low-power, low-interest category, particularly if that farmer were selling various retailers produce from his or her fields. However, if that same farmer could connect to a huge purveyor like Kroger, he or she could sell this giant customer its entire crop. This relationship places the farmer in the low-power, high-interest category, meaning he or she will most likely have to make price adjustments to make the sale. The model’s focus on power reveals a need for any company to carefully cultivate relationships with stakeholders. Not all stakeholders have equal influence with a firm. Still, no organization can blithely ignore any stakeholder without potentially debilitating economic consequences. For example, now that Amazon has acquired Whole Foods and increased the size of the customer stakeholder group, it must also find ways to personalize its communications with this group, because personal service has traditionally been more a hallmark of Whole Foods than of Amazon. Successful business practice today hinges on the ethical acknowledgement of stakeholder claims. It is the right thing to do. Not only that, it also engenders satisfied stakeholders, whether they be customers, stockowners, employees, or the community in which a firm is located. Naturally, satisfied stakeholders lead to the financial well-being of a company. Managing Stakeholder Expectations Stakeholder management does not work if the firm’s prioritizing decisions are based on flawed, inaccurate, or incomplete information. Some tools are available to help. MITRE is a nonprofit research and development consulting firm that helps governments and other large organizations with many stakeholders conduct stakeholder assessment. The MITRE Guide to Stakeholder Assessment and Management lays out a five-step system for stakeholder management. 18 Overall, MITRE stresses that an organization must sustain trust with its stakeholders through communication efforts. To accomplish this, however, stakeholders must first be clearly identified and then periodically reidentified, because stakeholder cohorts change in size and significance over time. The concerns or claims of stakeholders are identified through data gathering and analysis. Sometimes a firm will conduct surveys or focus groups with customers, suppliers, or other stakeholders. Other times, product usage data will be available as a function of sales figures and marketing data. For software in web and mobile applications, for example, user data may be readily available to show how stakeholders are using the company’s digital services or why they appear to be purchasing its products. Another source of stakeholder data is social media, where firms can monitor topics stakeholders of all types are talking about. What matters is gathering relevant and accurate data and ensuring that key stakeholders are providing it. In the next step, managers present the results of their research to the company’s decision makers or make decisions themselves. 19 Finally, stakeholders should be informed that their concerns were taken into consideration and that the company will continue to heed them. In other words, the firm should convey to them that they are important. Link to Learning One methodology for prioritizing stakeholder claims is the Stakeholder Circle, developed by Dr. Linda Bourne. Visit the Stakeholder Management website detailing the five key actions an organization can take using this model to learn more. What Would You Do? Malaysia Airlines Malaysia Airlines is owned by individual investors and the Malaysian government, which took over the company in 2014 after two mysterious jet crashes. The airline has lost money and struggled since that time, going through three CEOs. The current CEO, Peter Bellew, is experienced in tourism and travel and has been asked to cut costs and increase revenues. His strategy is to maximize the number of Malaysian Muslims (who make up more than 60 percent of the population) flying to Mecca for hajj, the annual holy pilgrimage and an obligation for all Muslims who are well enough to travel and can afford the trip. Bellew plans to provide charter flights to make the pilgrimage easier on travelers. 20 Critical Thinking Describe the passenger stakeholder claims on Malaysia Airlines. Describe the government stakeholder claims on Malaysia Airlines. What would you advise Bellew to identify as a priority—the demand from pilgrims for easy travel at a reduced price or the demand from the government for profitable operations? Explain your answer. Because every firm, no matter its mission, ultimately depends on the marketplace, its clients or customers are often high-priority stakeholders. Ethically, the company owes allegiance to customer stakeholders, but it also has an opportunity and perhaps a responsibility to shape their expectations in ways that encourage its growth and allow it to continue to provide for employees, suppliers, distributors, and shareholders. We should note, too, that nonprofit organizations are beholden, for the most part, to the same rules that apply to for-profits for their sustainability. Nonprofits typically provide a service that is just as dependent on cash flow as is the service or product of a for-profit. A significant difference, of course, is that the client or customer for a nonprofit’s service often is unable to pay for it. Therefore, the necessary cash must come from other sources, often in the form of donations or endowments. Hence, those who give to philanthropies constitute essential stakeholders for these nonprofits and must be acknowledged as such. Wesley E. Lindahl, who studies and advises nonprofits, notes that philanthropies have an ethical obligation to safeguard the donations that come their way. He likens this to a stewardship, because the monies given to charities are gifts intended for others very much in need of them. So those who manage nonprofits have a special obligation to ensure that these donations are well spent and distributed appropriately. 21 There are three major components to bringing about change in customer or donor expectations: (1) customer receptivity to a product or service offered by the company, (2) acknowledgement of the gap between customer receptivity and corporate action to reduce it, and (3) a system to bring about and maintain change in customer desires to bring it in line with precisely what the corporation can deliver. One example of firms altering customers’ habits is the evolution of beverage containers. Most soft drinks and other beverages such as beer were once delivered in reusable glass bottles. Customers were motivated to return the bottles by the refund of a minimal cash deposit originally paid at the time of purchase. The bottles had to be thick and sturdy for reuse, which resulted in substantial transportation costs, due to their weight. To reduce these costs of manufacturing and transportation, manufacturers first redesigned production to be local, and then, when technology allowed, introduced aluminum cans and pull tabs. Eventually, the cardboard carton that held bottles together was replaced by a plastic set of rings to hold aluminum cans together. Now, however, customers and other stakeholders object to the hazard these rings present to wildlife. Some firms have responded by redesigning their packaging yet again. This ongoing process of developing new packaging, listening to feedback, and redesigning the product over time ultimately changed stakeholder behavior and modernized the beverage industry. Stakeholders are essential parts of a cycle of mutual interest and involvement. Ethics Across Time and Cultures Going King Sized in the United States and Crashing on the Couch in China IKEA is a multinational corporation with a proven track record of listening to stakeholders in ways that improve relationships and the bottom line. The Swedish company has had success in the United States and, more recently, in China by adapting to local cultural norms. For example, in the United States, IKEA solicited the concerns of many of its approximately fifty thousand in-store customers and even visited some at home. The company learned, among other things, that U.S. customers assumed IKEA featured only European-size beds. In fact, IKEA has offered king-size beds for years; they simply were not on display. IKEA then began to focus on displaying furniture U.S. consumers were more familiar with and so grew its bedroom furniture sales in 2012 and 2013. 22 As IKEA expands into China, it has welcomed a different trend—people taking naps on the furniture on display. “While snoozing is prohibited at IKEA stores elsewhere, the Swedish retailer has long permitted Chinese customers to doze off, rather than alienate shoppers accustomed to sleeping in public.” 23 Adapting to local culture, as these examples demonstrate, is one way a company can respond to stakeholder wishes. The firm abandons some of its usual protocols in exchange for increasing consumer identification with its products. IKEA appears to have learned what many companies with a global presence have concluded: Stakeholders, and particularly consumer-stakeholders, have different expectations in different geographic settings. Because a firm’s ethical obligations include listening and responding to the needs of stakeholders, it behooves all international companies to appreciate the varying perspectives that geography and culture may produce among them. Critical Thinking Does IKEA have a system to influence stakeholder behavior? If so, describe the system and explain who changes more under the system, IKEA or its consumers. Does IKEA’s strategy reflect a normative approach to managing stakeholder claims? If so, how? The ethical responsibility of a stakeholder is to make known his or her preferences to the companies he or she purchases from or relies on. Such communication can lead to an increased commitment on the part of corporations to improve. To the extent they do so, companies act more ethically in responding to the wishes and needs of their stakeholders. 3.4 Corporate Social Responsibility (CSR) Learning Objectives By the end of this section, you will be able to: Define corporate social responsibility and the triple bottom line approach Compare the sincere application of CSR and its use as merely a public relations tool Explain why CSR ultimately benefits both companies and their stakeholders Thus far, we have discussed stakeholders mostly as individuals and groups outside the organization. This section focuses on the business firm as a stakeholder in its environment and examines the concept of a corporation as a socially responsible entity conscious of the influences it has on society. That is, we look at the role companies, and large corporations in particular, play as active stakeholders in communities. Corporations, by their sheer size, affect their local, regional, national, and global communities. Creating a positive impact in these communities may mean providing jobs, strengthening economies, or driving innovation. Negative impacts may include doing damage to the environment, forcing the exit of smaller competitors, and offering poor customer service, to name a few. This section examines the concept of a corporation as a socially responsible entity conscious of the influences it has on society. Corporate Social Responsibility Defined In recent years, many organizations have embraced corporate social responsibility (CSR), a philosophy (introduced in Why Ethics Matter ,) in which the company’s expected actions include not only producing a reliable product, charging a fair price with fair profit margins, and paying a fair wage to employees, but also caring for the environment and acting on other social concerns. Many corporations work on prosocial endeavors and share that information with their customers and the communities where they do business. CSR, when conducted in good faith, is beneficial to corporations and their stakeholders. This is especially true for stakeholders that have typically been given low priority and little voice, such as the natural environment and community members who live near corporate sites and manufacturing facilities. CSR in its ideal form focuses managers on demonstrating the social good of their new products and endeavors. It can be framed as a response to the backlash corporations face for a long track record of harming environments and communities in their efforts to be more efficient and profitable. Pushback is not new. Charles Dickens wrote about the effects of the coal economy on nineteenth-century England and shaped the way we think about the early industrial revolution. The twentieth-century writer Chinua Achebe, among many others, wrote about colonization and its transformative and often painful effect on African cultures. Rachel Carson first brought public attention to corporation’s chemical poisoning of U.S. waterways in her 1962 book Silent Spring . Betty Friedan’s The Feminine Mystique (1963) critiqued the way twentieth-century industrialization boxed women into traditional roles and limited their agency. Kate Chopin’s novel The Awakening (1899) and the nineteenth-century novels of Jane Austen had already outlined how limited options were for women despite massive social and economic shifts in the industrializing West. Stakeholder communities left out of or directly harmed by the economic revolution have demanded that they be able to influence corporate and governmental economic practices to benefit more directly from corporate growth as well as entrepreneurship opportunities. The trend to adopt CSR may represent an opportunity for greater engagement and involvement by groups mostly ignored until now by the wave of corporate economic growth reshaping the industrialized world. CSR and the Environment Corporations have responded to stakeholder concerns about the environment and sustainability. In 1999, Dow Jones began publishing an annual list of companies for which sustainability was important. Sustainability is the practice of preserving resources and operating in a way that is ecologically responsible in the long term. 24 The Dow Jones Sustainability Indices “serve as benchmarks for investors who integrate sustainability considerations into their portfolios.” 25 There is a growing awareness that human actions can, and do, harm the environment. Destruction of the environment can ultimately lead to reduction of resources, declining business opportunities, and lowered quality of life. Enlightened business stakeholders realize that profit is only one positive effect of business operations. In addition to safeguarding the environment, other ethical contributions that stakeholders could lobby corporate management to make include establishing schools and health clinics in impoverished neighborhoods and endowing worthwhile philanthropies in the communities where companies have a presence. Other stakeholders, such as state governments, NGOs, citizen groups, and political action committees in the United States apply social and legal pressure on businesses to improve their environmental practices. For example, the state of California in 2015 enacted a set of laws, referred to as the California Transparency in Supply Chains Act, which requires firms to report on the working conditions of the employees of their suppliers. The law requires only disclosures, but the added transparency is a step toward holding U.S. and other multinational corporations responsible for what goes on before their products appear in shiny packages in stores. The legislators who wrote California’s Supply Chains Act recognize that consumer stakeholders are likely to bring pressure to bear on companies found to use slave labor in their supply chains, so forcing disclosure can bring about change because corporations would rather adjust their relationships with supply-chain stakeholders than risk alienating massive numbers of customers. 26 As instances of this type of pressure on corporations increase around the world, stakeholder groups become simultaneously less isolated and more powerful. Firms need customers. Customers need employment, and the state needs taxes just as firms need resources. All stakeholders exist in an interdependent network of relationships, and what is most needed is a sustainable system that enables all types of key stakeholders to establish and apply influence. People, Planet, Profit: The Triple Bottom Line How can corporations and their stakeholders measure some of the effects of CSR programs? The triple bottom line (TBL) offers a way. TBL is a measure described in 1994 by John Elkington, a British business consultant ( Figure 3.6 ), and it forces us to reconsider the very concept of the “bottom line.” Most businesses, and most consumers for that matter, think of the bottom line as a shorthand expression of their financial well-being. Are they making a profit, staying solvent, or falling into debt? That is the customary bottom line, but Elkington suggests that businesses need to consider not just one but rather three measures of their true bottom line: the economic and also the social and environmental results of their actions. The social and environmental impacts of doing business, called people and planet in the TBL, are the externalities of their operations that companies must take into account. The TBL concept recognizes that external stakeholders consider it a corporation’s responsibility to go beyond making money. If increasing wealth damages the environment or makes people sick, society demands that the corporation revise its methods or leave the community. Society, businesses, and governments have realized that all stakeholders have to work for the common good. When they are successful at acting in a socially responsible way, corporations will and should claim credit. In acting according to the TBL model and promoting such acts, many corporations have reinvested their efforts and their profits in ways that can ultimately lead to the development of a sustainable economic system. CSR as Public Relations Tool On the other hand, for some, CSR is nothing more than an opportunity for publicity as a firm tries to look good through various environmentally or socially friendly initiatives without making systemic changes that will have long-term positive effects. Carrying out superficial CSR efforts that merely cover up systemic ethics problems in this inauthentic way (especially as it applies to the environment), and acting simply for the sake of public relations is called greenwashing . To truly understand a company’s approach toward the environment, we need to do more than blindly accept the words on its website or its advertising. Cases from the Real World When an Image of Social Responsibility May Be Greenwashing Ben and Jerry’s Ice Cream started as a small ice cream stand in Vermont and based its products on pure, locally supplied dairy and agricultural products. The company grew quickly and is now a global brand owned by Unilever, an international consumer goods company co-headquartered in Rotterdam, The Netherlands, and London, United Kingdom. According to its statement of values, Ben and Jerry’s mission is threefold: “Our Product Mission drives us to make fantastic ice cream—for its own sake. Our Economic Mission asks us to manage our Company for sustainable financial growth. Our Social Mission compels us to use our Company in innovative ways to make the world a better place.” With its expansion, however, Ben and Jerry’s had to get its milk—the main raw ingredient of ice cream—from larger suppliers, most of which use confined-animal feeding operations (CAFOs). CAFOs have been condemned by animal-rights activists as harmful to the well-being of the animals. Consumer activists also claim that CAFOs contribute significantly to pollution because they release heavy concentrations of animal waste into the ground, water sources, and air. Critical Thinking Does the use of CAFOs compromise Ben and Jerry’s mission? Why or why not? Has the growth of Ben and Jerry’s contributed to any form of greenwashing by the parent company, Unilever? If so, how? Link to Learning Read Ben and Jerry’s Statement of Mission for more on the company’s values and mission. Coca-Cola provides another example of practices some would identify as greenwashing. The company states the following on its website: “Engaging our diverse stakeholders in long-term dialogue provides important input that informs our decision making, and helps us continuously improve and make progress toward our 2020 sustainability goals . . . We are committed to ongoing stakeholder engagement as a core component of our business and sustainability strategies, our annual reporting process, and our activities around the world. As active members of the communities where we live and work, we want to strengthen the fabric of our communities so that we can prosper together.” 27 Let us take a close look at this statement. “Engaging stakeholders in long-term dialogue” appears to describe an ongoing and reciprocal relationship that helps improvement be continuous. Commitment to “stakeholder engagement as a core component of business and sustainability strategies” appears to focus the company on the requirement to conduct clear, honest, transparent reporting. Currently 20 percent of the people on Earth consume a Coca-Cola product each day, meaning a very large portion of the global population belongs to the company’s consumer stakeholder group. Depending on the process and location, it is estimated that it takes more than three liters of water to produce a liter of Coke. Each day, therefore, millions of liters of water are removed from the Earth to make Coke products, so the company’s water footprint can endanger the water supplies of both employee and neighbor stakeholders. For example, in Chiapas, Mexico, the Coca-Cola bottling plant consumes more than one billion liters of water daily, but only about half the population has running water. 28 Mexico leads the world in per capita consumption of Coke products. If consumers are aware only of Coca-Cola’s advertising campaigns and corporate public relations writings online, they will miss the very real concerns about water security associated with it and other corporations producing beverages in similar fashion. Thus it requires interest on the part of stakeholders to continue to drive real CSR practices and to differentiate true CSR efforts from greenwashing. The Ultimate Stakeholder Benefit CSR used in good faith has the potential to reshape the orientation of multinational corporations to their stakeholders. By positioning themselves as stakeholders in a broader global community, conscientious corporations can be exemplary organizations. They can demonstrate interest and influence on a global scale and improve the way the manufacture of goods and delivery of services serve the local and global environment. They can return to communities as much as they extract and foster automatic financial reinvestment so that people willing and able to work for them can afford not only the necessities but a chance to pursue happiness. In return, global corporations will have sustainable business models that look beyond short-term growth forecasts. They will have a method of operating and a framework for thinking about sustained growth with stakeholders and as stakeholders. Ethical stakeholder relationships systematically grow wealth and opportunity in dynamic fashion. Without them, the global consumer economy may fail. On an alternate and ethical path of prosperity, today’s supplier is a consumer in the next generation and Earth is still inhabitable after many generations of dynamic change and continued global growth.
biology
Chapter Outline 8.1 Overview of Photosynthesis 8.2 The Light-Dependent Reactions of Photosynthesis 8.3 Using Light Energy to Make Organic Molecules Introduction The processes in all organisms—from bacteria to humans—require energy. To get this energy, many organisms access stored energy by eating, that is, by ingesting other organisms. But where does the stored energy in food originate? All of this energy can be traced back to photosynthesis.
[ { "answer": { "ans_choice": 0, "ans_text": "chloroplasts" }, "bloom": "2", "hl_context": "<hl> In plants , carbon dioxide ( CO 2 ) enters the leaves through stomata , where it diffuses over short distances through intercellular spaces until it reaches the mesophyll cells . <hl> <hl> Once in the mesophyll cells , CO 2 diffuses into the stroma of the chloroplast — the site of light-independent reactions of photosynthesis . <hl> These reactions actually have several names associated with them . Another term , the Calvin cycle , is named for the man who discovered it , and because these reactions function as a cycle . Others call it the Calvin-Benson cycle to include the name of another scientist involved in its discovery . The most outdated name is dark reactions , because light is not directly required ( Figure 8.17 ) . However , the term dark reaction can be misleading because it implies incorrectly that the reaction only occurs at night or is independent of light , which is why most scientists and instructors no longer use it . In plants , photosynthesis generally takes place in leaves , which consist of several layers of cells . The process of photosynthesis occurs in a middle layer called the mesophyll . The gas exchange of carbon dioxide and oxygen occurs through small , regulated openings called stomata ( singular : stoma ) , which also play roles in the regulation of gas exchange and water balance . The stomata are typically located on the underside of the leaf , which helps to minimize water loss . Each stoma is flanked by guard cells that regulate the opening and closing of the stomata by swelling or shrinking in response to osmotic changes . <hl> In all autotrophic eukaryotes , photosynthesis takes place inside an organelle called a chloroplast . <hl> <hl> For plants , chloroplast-containing cells exist in the mesophyll . <hl> Chloroplasts have a double membrane envelope ( composed of an outer membrane and an inner membrane ) . Within the chloroplast are stacked , disc-shaped structures called thylakoids . Embedded in the thylakoid membrane is chlorophyll , a pigment ( molecule that absorbs light ) responsible for the initial interaction between light and plant material , and numerous proteins that make up the electron transport chain . The thylakoid membrane encloses an internal space called the thylakoid lumen . As shown in Figure 8.6 , a stack of thylakoids is called a granum , and the liquid-filled space surrounding the granum is called stroma or “ bed ” ( not to be confused with stoma or “ mouth , ” an opening on the leaf epidermis ) . Visual Connection", "hl_sentences": "In plants , carbon dioxide ( CO 2 ) enters the leaves through stomata , where it diffuses over short distances through intercellular spaces until it reaches the mesophyll cells . Once in the mesophyll cells , CO 2 diffuses into the stroma of the chloroplast — the site of light-independent reactions of photosynthesis . In all autotrophic eukaryotes , photosynthesis takes place inside an organelle called a chloroplast . For plants , chloroplast-containing cells exist in the mesophyll .", "question": { "cloze_format": "The component ___ is not used by both plants and cyanobacteria to carry out photosynthesis.", "normal_format": "Which of the following components is not used by both plants and cyanobacteria to carry out photosynthesis?", "question_choices": [ "chloroplasts", "chlorophyll", "carbon dioxide", "water" ], "question_id": "fs-idm106883952", "question_text": "Which of the following components is not used by both plants and cyanobacteria to carry out photosynthesis?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 2, "ans_text": "sugars/carbohydrates and oxygen" }, "bloom": "2", "hl_context": "Photosynthesis is a multi-step process that requires sunlight , carbon dioxide ( which is low in energy ) , and water as substrates ( Figure 8.4 ) . <hl> After the process is complete , it releases oxygen and produces glyceraldehyde - 3 - phosphate ( GA3P ) , simple carbohydrate molecules ( which are high in energy ) that can subsequently be converted into glucose , sucrose , or any of dozens of other sugar molecules . <hl> These sugar molecules contain energy and the energized carbon that all living things need to survive .", "hl_sentences": "After the process is complete , it releases oxygen and produces glyceraldehyde - 3 - phosphate ( GA3P ) , simple carbohydrate molecules ( which are high in energy ) that can subsequently be converted into glucose , sucrose , or any of dozens of other sugar molecules .", "question": { "cloze_format": "The two main products that result from photosynthesis are ___ .", "normal_format": "What two main products result from photosynthesis?", "question_choices": [ "oxygen and carbon dioxide", "chlorophyll and oxygen", "sugars/carbohydrates and oxygen", "sugars/carbohydrates and carbon dioxide" ], "question_id": "fs-idp62360928", "question_text": "What two main products result from photosynthesis?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 1, "ans_text": "stroma" }, "bloom": "2", "hl_context": "In plants , carbon dioxide ( CO 2 ) enters the leaves through stomata , where it diffuses over short distances through intercellular spaces until it reaches the mesophyll cells . <hl> Once in the mesophyll cells , CO 2 diffuses into the stroma of the chloroplast — the site of light-independent reactions of photosynthesis . <hl> These reactions actually have several names associated with them . Another term , the Calvin cycle , is named for the man who discovered it , and because these reactions function as a cycle . Others call it the Calvin-Benson cycle to include the name of another scientist involved in its discovery . The most outdated name is dark reactions , because light is not directly required ( Figure 8.17 ) . However , the term dark reaction can be misleading because it implies incorrectly that the reaction only occurs at night or is independent of light , which is why most scientists and instructors no longer use it .", "hl_sentences": "Once in the mesophyll cells , CO 2 diffuses into the stroma of the chloroplast — the site of light-independent reactions of photosynthesis .", "question": { "cloze_format": "The compartment of the plant cell in which the light-independent reactions of photosynthesis take place is the ___ .", "normal_format": "In which compartment of the plant cell do the light-independent reactions of photosynthesis take place?", "question_choices": [ "thylakoid", "stroma", "outer membrane", "mesophyll" ], "question_id": "fs-idm83342320", "question_text": "In which compartment of the plant cell do the light-independent reactions of photosynthesis take place?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 1, "ans_text": "Thylakoids exist as a maze of folded membranes." }, "bloom": null, "hl_context": "In plants , photosynthesis generally takes place in leaves , which consist of several layers of cells . The process of photosynthesis occurs in a middle layer called the mesophyll . The gas exchange of carbon dioxide and oxygen occurs through small , regulated openings called stomata ( singular : stoma ) , which also play roles in the regulation of gas exchange and water balance . The stomata are typically located on the underside of the leaf , which helps to minimize water loss . Each stoma is flanked by guard cells that regulate the opening and closing of the stomata by swelling or shrinking in response to osmotic changes . In all autotrophic eukaryotes , photosynthesis takes place inside an organelle called a chloroplast . For plants , chloroplast-containing cells exist in the mesophyll . Chloroplasts have a double membrane envelope ( composed of an outer membrane and an inner membrane ) . <hl> Within the chloroplast are stacked , disc-shaped structures called thylakoids . <hl> <hl> Embedded in the thylakoid membrane is chlorophyll , a pigment ( molecule that absorbs light ) responsible for the initial interaction between light and plant material , and numerous proteins that make up the electron transport chain . <hl> The thylakoid membrane encloses an internal space called the thylakoid lumen . <hl> As shown in Figure 8.6 , a stack of thylakoids is called a granum , and the liquid-filled space surrounding the granum is called stroma or “ bed ” ( not to be confused with stoma or “ mouth , ” an opening on the leaf epidermis ) . <hl> Visual Connection", "hl_sentences": "Within the chloroplast are stacked , disc-shaped structures called thylakoids . Embedded in the thylakoid membrane is chlorophyll , a pigment ( molecule that absorbs light ) responsible for the initial interaction between light and plant material , and numerous proteins that make up the electron transport chain . As shown in Figure 8.6 , a stack of thylakoids is called a granum , and the liquid-filled space surrounding the granum is called stroma or “ bed ” ( not to be confused with stoma or “ mouth , ” an opening on the leaf epidermis ) .", "question": { "cloze_format": "The statement about thylakoids in eukaryotes that is not correct is that ___.", "normal_format": "Which statement about thylakoids in eukaryotes is not correct?", "question_choices": [ "Thylakoids are assembled into stacks.", "Thylakoids exist as a maze of folded membranes.", "The space surrounding thylakoids is called stroma.", "Thylakoids contain chlorophyll." ], "question_id": "fs-idm72864672", "question_text": "Which statement about thylakoids in eukaryotes is not correct?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 0, "ans_text": "ATP synthase" }, "bloom": "1", "hl_context": "<hl> The reaction center of PSII ( called P680 ) delivers its high-energy electrons , one at the time , to the primary electron acceptor , and through the electron transport chain ( Pq to cytochrome complex to plastocyanine ) to PSI . <hl> P680 ’ s missing electron is replaced by extracting a low-energy electron from water ; thus , water is split and PSII is re-reduced after every photoact . Splitting one H 2 O molecule releases two electrons , two hydrogen atoms , and one atom of oxygen . Splitting two molecules is required to form one molecule of diatomic O 2 gas . About 10 percent of the oxygen is used by mitochondria in the leaf to support oxidative phosphorylation . The remainder escapes to the atmosphere where it is used by aerobic organisms to support respiration . As electrons move through the proteins that reside between PSII and PSI , they lose energy . That energy is used to move hydrogen atoms from the stromal side of the membrane to the thylakoid lumen . Those hydrogen atoms , plus the ones produced by splitting water , accumulate in the thylakoid lumen and will be used synthesize ATP in a later step . Because the electrons have lost energy prior to their arrival at PSI , they must be re-energized by PSI , hence , another photon is absorbed by the PSI antenna . That energy is relayed to the PSI reaction center ( called P700 ) . P700 is oxidized and sends a high-energy electron to NADP + to form NADPH . Thus , PSII captures the energy to create proton gradients to make ATP , and PSI captures the energy to reduce NADP + into NADPH . The two photosystems work in concert , in part , to guarantee that the production of NADPH will roughly equal the production of ATP . Other mechanisms exist to fine tune that ratio to exactly match the chloroplast ’ s constantly changing energy needs . Generating an Energy Carrier : ATP <hl> Both photosystems have the same basic structure ; a number of antenna proteins to which the chlorophyll molecules are bound surround the reaction center where the photochemistry takes place . <hl> Each photosystem is serviced by the light-harvesting complex , which passes energy from sunlight to the reaction center ; it consists of multiple antenna proteins that contain a mixture of 300 – 400 chlorophyll a and b molecules as well as other pigments like carotenoids . The absorption of a single photon or distinct quantity or “ packet ” of light by any of the chlorophylls pushes that molecule into an excited state . In short , the light energy has now been captured by biological molecules but is not stored in any useful form yet . The energy is transferred from chlorophyll to chlorophyll until eventually ( after about a millionth of a second ) , it is delivered to the reaction center . Up to this point , only energy has been transferred between molecules , not electrons .", "hl_sentences": "The reaction center of PSII ( called P680 ) delivers its high-energy electrons , one at the time , to the primary electron acceptor , and through the electron transport chain ( Pq to cytochrome complex to plastocyanine ) to PSI . Both photosystems have the same basic structure ; a number of antenna proteins to which the chlorophyll molecules are bound surround the reaction center where the photochemistry takes place .", "question": { "cloze_format": "The ___ is a structure that is not a component of a photosystem.", "normal_format": "Which of the following structures is not a component of a photosystem?", "question_choices": [ "ATP synthase", "antenna molecule", "reaction center", "primary electron acceptor" ], "question_id": "fs-idm197809616", "question_text": "Which of the following structures is not a component of a photosystem?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 2, "ans_text": "photosystem II" }, "bloom": null, "hl_context": "As in the intermembrane space of the mitochondria during cellular respiration , the buildup of hydrogen ions inside the thylakoid lumen creates a concentration gradient . <hl> The passive diffusion of hydrogen ions from high concentration ( in the thylakoid lumen ) to low concentration ( in the stroma ) is harnessed to create ATP , just as in the electron transport chain of cellular respiration . <hl> The ions build up energy because of diffusion and because they all have the same electrical charge , repelling each other . To release this energy , hydrogen ions will rush through any opening , similar to water jetting through a hole in a dam . <hl> In the thylakoid , that opening is a passage through a specialized protein channel called the ATP synthase . <hl> The energy released by the hydrogen ion stream allows ATP synthase to attach a third phosphate group to ADP , which forms a molecule of ATP ( Figure 8.16 ) . The flow of hydrogen ions through ATP synthase is called chemiosmosis because the ions move from an area of high to an area of low concentration through a semi-permeable structure . Link to Learning <hl> The reaction center of PSII ( called P680 ) delivers its high-energy electrons , one at the time , to the primary electron acceptor , and through the electron transport chain ( Pq to cytochrome complex to plastocyanine ) to PSI . <hl> P680 ’ s missing electron is replaced by extracting a low-energy electron from water ; thus , water is split and PSII is re-reduced after every photoact . Splitting one H 2 O molecule releases two electrons , two hydrogen atoms , and one atom of oxygen . Splitting two molecules is required to form one molecule of diatomic O 2 gas . About 10 percent of the oxygen is used by mitochondria in the leaf to support oxidative phosphorylation . The remainder escapes to the atmosphere where it is used by aerobic organisms to support respiration . <hl> As electrons move through the proteins that reside between PSII and PSI , they lose energy . <hl> <hl> That energy is used to move hydrogen atoms from the stromal side of the membrane to the thylakoid lumen . <hl> <hl> Those hydrogen atoms , plus the ones produced by splitting water , accumulate in the thylakoid lumen and will be used synthesize ATP in a later step . <hl> Because the electrons have lost energy prior to their arrival at PSI , they must be re-energized by PSI , hence , another photon is absorbed by the PSI antenna . That energy is relayed to the PSI reaction center ( called P700 ) . P700 is oxidized and sends a high-energy electron to NADP + to form NADPH . <hl> Thus , PSII captures the energy to create proton gradients to make ATP , and PSI captures the energy to reduce NADP + into NADPH . <hl> <hl> The two photosystems work in concert , in part , to guarantee that the production of NADPH will roughly equal the production of ATP . <hl> Other mechanisms exist to fine tune that ratio to exactly match the chloroplast ’ s constantly changing energy needs . Generating an Energy Carrier : ATP The reaction center contains a pair of chlorophyll a molecules with a special property . Those two chlorophylls can undergo oxidation upon excitation ; they can actually give up an electron in a process called a photoact . It is at this step in the reaction center , this step in photosynthesis , that light energy is converted into an excited electron . All of the subsequent steps involve getting that electron onto the energy carrier NADPH for delivery to the Calvin cycle where the electron is deposited onto carbon for long-term storage in the form of a carbohydrate.PSII and PSI are two major components of the photosynthetic electron transport chain , which also includes the cytochrome complex . <hl> The cytochrome complex , an enzyme composed of two protein complexes , transfers the electrons from the carrier molecule plastoquinone ( Pq ) to the protein plastocyanin ( Pc ) , thus enabling both the transfer of protons across the thylakoid membrane and the transfer of electrons from PSII to PSI . <hl>", "hl_sentences": "The passive diffusion of hydrogen ions from high concentration ( in the thylakoid lumen ) to low concentration ( in the stroma ) is harnessed to create ATP , just as in the electron transport chain of cellular respiration . In the thylakoid , that opening is a passage through a specialized protein channel called the ATP synthase . The reaction center of PSII ( called P680 ) delivers its high-energy electrons , one at the time , to the primary electron acceptor , and through the electron transport chain ( Pq to cytochrome complex to plastocyanine ) to PSI . As electrons move through the proteins that reside between PSII and PSI , they lose energy . That energy is used to move hydrogen atoms from the stromal side of the membrane to the thylakoid lumen . Those hydrogen atoms , plus the ones produced by splitting water , accumulate in the thylakoid lumen and will be used synthesize ATP in a later step . Thus , PSII captures the energy to create proton gradients to make ATP , and PSI captures the energy to reduce NADP + into NADPH . The two photosystems work in concert , in part , to guarantee that the production of NADPH will roughly equal the production of ATP . The cytochrome complex , an enzyme composed of two protein complexes , transfers the electrons from the carrier molecule plastoquinone ( Pq ) to the protein plastocyanin ( Pc ) , thus enabling both the transfer of protons across the thylakoid membrane and the transfer of electrons from PSII to PSI .", "question": { "cloze_format": "___ is a complex that is not involved in the establishment of conditions for ATP synthesis.", "normal_format": "Which complex is not involved in the establishment of conditions for ATP synthesis?", "question_choices": [ "photosystem I", "ATP synthase", "photosystem II", "cytochrome complex" ], "question_id": "fs-idm144749168", "question_text": "Which complex is not involved in the establishment of conditions for ATP synthesis?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 1, "ans_text": "photosystem I" }, "bloom": null, "hl_context": "The reaction center of PSII ( called P680 ) delivers its high-energy electrons , one at the time , to the primary electron acceptor , and through the electron transport chain ( Pq to cytochrome complex to plastocyanine ) to PSI . P680 ’ s missing electron is replaced by extracting a low-energy electron from water ; thus , water is split and PSII is re-reduced after every photoact . Splitting one H 2 O molecule releases two electrons , two hydrogen atoms , and one atom of oxygen . Splitting two molecules is required to form one molecule of diatomic O 2 gas . About 10 percent of the oxygen is used by mitochondria in the leaf to support oxidative phosphorylation . The remainder escapes to the atmosphere where it is used by aerobic organisms to support respiration . As electrons move through the proteins that reside between PSII and PSI , they lose energy . That energy is used to move hydrogen atoms from the stromal side of the membrane to the thylakoid lumen . Those hydrogen atoms , plus the ones produced by splitting water , accumulate in the thylakoid lumen and will be used synthesize ATP in a later step . Because the electrons have lost energy prior to their arrival at PSI , they must be re-energized by PSI , hence , another photon is absorbed by the PSI antenna . That energy is relayed to the PSI reaction center ( called P700 ) . P700 is oxidized and sends a high-energy electron to NADP + to form NADPH . <hl> Thus , PSII captures the energy to create proton gradients to make ATP , and PSI captures the energy to reduce NADP + into NADPH . <hl> The two photosystems work in concert , in part , to guarantee that the production of NADPH will roughly equal the production of ATP . Other mechanisms exist to fine tune that ratio to exactly match the chloroplast ’ s constantly changing energy needs . Generating an Energy Carrier : ATP", "hl_sentences": "Thus , PSII captures the energy to create proton gradients to make ATP , and PSI captures the energy to reduce NADP + into NADPH .", "question": { "cloze_format": "___ is the component of the light-dependent reactions from which NADPH form most directly.", "normal_format": "From which component of the light-dependent reactions does NADPH form most directly?", "question_choices": [ "photosystem II", "photosystem I", "cytochrome complex", "ATP synthase" ], "question_id": "fs-idm133171248", "question_text": "From which component of the light-dependent reactions does NADPH form most directly?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 3, "ans_text": "CO2" }, "bloom": "1", "hl_context": "<hl> In plants , carbon dioxide ( CO 2 ) enters the leaves through stomata , where it diffuses over short distances through intercellular spaces until it reaches the mesophyll cells . <hl> <hl> Once in the mesophyll cells , CO 2 diffuses into the stroma of the chloroplast — the site of light-independent reactions of photosynthesis . <hl> <hl> These reactions actually have several names associated with them . <hl> <hl> Another term , the Calvin cycle , is named for the man who discovered it , and because these reactions function as a cycle . <hl> Others call it the Calvin-Benson cycle to include the name of another scientist involved in its discovery . The most outdated name is dark reactions , because light is not directly required ( Figure 8.17 ) . However , the term dark reaction can be misleading because it implies incorrectly that the reaction only occurs at night or is independent of light , which is why most scientists and instructors no longer use it .", "hl_sentences": "In plants , carbon dioxide ( CO 2 ) enters the leaves through stomata , where it diffuses over short distances through intercellular spaces until it reaches the mesophyll cells . Once in the mesophyll cells , CO 2 diffuses into the stroma of the chloroplast — the site of light-independent reactions of photosynthesis . These reactions actually have several names associated with them . Another term , the Calvin cycle , is named for the man who discovered it , and because these reactions function as a cycle .", "question": { "cloze_format": "The ___ molecule must enter the Calvin cycle continually for the light-independent reactions to take place.", "normal_format": "Which molecule must enter the Calvin cycle continually for the light-independent reactions to take place?", "question_choices": [ "RuBisCO", "RuBP", "3-PGA", "CO2" ], "question_id": "fs-idm107405520", "question_text": "Which molecule must enter the Calvin cycle continually for the light-independent reactions to take place?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 2, "ans_text": "chloroplast stroma" }, "bloom": null, "hl_context": "In plants , carbon dioxide ( CO 2 ) enters the leaves through stomata , where it diffuses over short distances through intercellular spaces until it reaches the mesophyll cells . <hl> Once in the mesophyll cells , CO 2 diffuses into the stroma of the chloroplast — the site of light-independent reactions of photosynthesis . <hl> <hl> These reactions actually have several names associated with them . <hl> <hl> Another term , the Calvin cycle , is named for the man who discovered it , and because these reactions function as a cycle . <hl> Others call it the Calvin-Benson cycle to include the name of another scientist involved in its discovery . The most outdated name is dark reactions , because light is not directly required ( Figure 8.17 ) . However , the term dark reaction can be misleading because it implies incorrectly that the reaction only occurs at night or is independent of light , which is why most scientists and instructors no longer use it .", "hl_sentences": "Once in the mesophyll cells , CO 2 diffuses into the stroma of the chloroplast — the site of light-independent reactions of photosynthesis . These reactions actually have several names associated with them . Another term , the Calvin cycle , is named for the man who discovered it , and because these reactions function as a cycle .", "question": { "cloze_format": "In eukaryotic cells the Calvin cycle takes place in the ___.", "normal_format": "Where in eukaryotic cells does the Calvin cycle take place?", "question_choices": [ "thylakoid membrane", "thylakoid lumen", "chloroplast stroma", "granum" ], "question_id": "fs-idm99331456", "question_text": "Where in eukaryotic cells does the Calvin cycle take place?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 0, "ans_text": "the conversion of CO2 into an organic compound" }, "bloom": "2", "hl_context": "RuBisCO catalyzes a reaction between CO 2 and RuBP . For each CO 2 molecule that reacts with one RuBP , two molecules of another compound ( 3 - PGA ) form . PGA has three carbons and one phosphate . Each turn of the cycle involves only one RuBP and one carbon dioxide and forms two molecules of 3 - PGA . The number of carbon atoms remains the same , as the atoms move to form new bonds during the reactions ( 3 atoms from 3CO 2 + 15 atoms from 3RuBP = 18 atoms in 3 atoms of 3 - PGA ) . <hl> This process is called carbon fixation , because CO 2 is “ fixed ” from an inorganic form into organic molecules . <hl>", "hl_sentences": "This process is called carbon fixation , because CO 2 is “ fixed ” from an inorganic form into organic molecules .", "question": { "cloze_format": "Carbon fixation is correctly described as ___ .", "normal_format": "Which statement correctly describes carbon fixation?", "question_choices": [ "the conversion of CO2 into an organic compound", "the use of RuBisCO to form 3-PGA", "the production of carbohydrate molecules from G3P", "the formation of RuBP from G3P molecules", "the use of ATP and NADPH to reduce CO2" ], "question_id": "fs-idm55613456", "question_text": "Which statement correctly describes carbon fixation?" }, "references_are_paraphrase": null } ]
8
8.1 Overview of Photosynthesis Learning Objectives By the end of this section, you will be able to: Explain the relevance of photosynthesis to other living things Describe the main structures involved in photosynthesis Identify the substrates and products of photosynthesis Summarize the process of photosynthesis Photosynthesis is essential to all life on earth; both plants and animals depend on it. It is the only biological process that can capture energy that originates in outer space (sunlight) and convert it into chemical compounds (carbohydrates) that every organism uses to power its metabolism. In brief, the energy of sunlight is captured and used to energize electrons, which are then stored in the covalent bonds of sugar molecules. How long lasting and stable are those covalent bonds? The energy extracted today by the burning of coal and petroleum products represents sunlight energy captured and stored by photosynthesis almost 200 million years ago. Plants, algae, and a group of bacteria called cyanobacteria are the only organisms capable of performing photosynthesis ( Figure 8.2 ). Because they use light to manufacture their own food, they are called photoautotrophs (literally, “self-feeders using light”). Other organisms, such as animals, fungi, and most other bacteria, are termed heterotrophs (“other feeders”), because they must rely on the sugars produced by photosynthetic organisms for their energy needs. A third very interesting group of bacteria synthesize sugars, not by using sunlight’s energy, but by extracting energy from inorganic chemical compounds; hence, they are referred to as chemoautotrophs . The importance of photosynthesis is not just that it can capture sunlight’s energy. A lizard sunning itself on a cold day can use the sun’s energy to warm up. Photosynthesis is vital because it evolved as a way to store the energy in solar radiation (the “photo-” part) as high-energy electrons in the carbon-carbon bonds of carbohydrate molecules (the “-synthesis” part). Those carbohydrates are the energy source that heterotrophs use to power the synthesis of ATP via respiration. Therefore, photosynthesis powers 99 percent of Earth’s ecosystems. When a top predator, such as a wolf, preys on a deer ( Figure 8.3 ), the wolf is at the end of an energy path that went from nuclear reactions on the surface of the sun, to light, to photosynthesis, to vegetation, to deer, and finally to wolf. Main Structures and Summary of Photosynthesis Photosynthesis is a multi-step process that requires sunlight, carbon dioxide (which is low in energy), and water as substrates ( Figure 8.4 ). After the process is complete, it releases oxygen and produces glyceraldehyde-3-phosphate (GA3P), simple carbohydrate molecules (which are high in energy) that can subsequently be converted into glucose, sucrose, or any of dozens of other sugar molecules. These sugar molecules contain energy and the energized carbon that all living things need to survive. The following is the chemical equation for photosynthesis ( Figure 8.5 ): Although the equation looks simple, the many steps that take place during photosynthesis are actually quite complex. Before learning the details of how photoautotrophs turn sunlight into food, it is important to become familiar with the structures involved. In plants, photosynthesis generally takes place in leaves, which consist of several layers of cells. The process of photosynthesis occurs in a middle layer called the mesophyll . The gas exchange of carbon dioxide and oxygen occurs through small, regulated openings called stomata (singular: stoma), which also play roles in the regulation of gas exchange and water balance. The stomata are typically located on the underside of the leaf, which helps to minimize water loss. Each stoma is flanked by guard cells that regulate the opening and closing of the stomata by swelling or shrinking in response to osmotic changes. In all autotrophic eukaryotes, photosynthesis takes place inside an organelle called a chloroplast . For plants, chloroplast-containing cells exist in the mesophyll. Chloroplasts have a double membrane envelope (composed of an outer membrane and an inner membrane). Within the chloroplast are stacked, disc-shaped structures called thylakoids . Embedded in the thylakoid membrane is chlorophyll, a pigment (molecule that absorbs light) responsible for the initial interaction between light and plant material, and numerous proteins that make up the electron transport chain. The thylakoid membrane encloses an internal space called the thylakoid lumen . As shown in Figure 8.6 , a stack of thylakoids is called a granum , and the liquid-filled space surrounding the granum is called stroma or “bed” (not to be confused with stoma or “mouth,” an opening on the leaf epidermis). Visual Connection On a hot, dry day, plants close their stomata to conserve water. What impact will this have on photosynthesis? The Two Parts of Photosynthesis Photosynthesis takes place in two sequential stages: the light-dependent reactions and the light independent-reactions. In the light-dependent reactions , energy from sunlight is absorbed by chlorophyll and that energy is converted into stored chemical energy. In the light-independent reactions , the chemical energy harvested during the light-dependent reactions drive the assembly of sugar molecules from carbon dioxide. Therefore, although the light-independent reactions do not use light as a reactant, they require the products of the light-dependent reactions to function. In addition, several enzymes of the light-independent reactions are activated by light. The light-dependent reactions utilize certain molecules to temporarily store the energy: These are referred to as energy carriers. The energy carriers that move energy from light-dependent reactions to light-independent reactions can be thought of as “full” because they are rich in energy. After the energy is released, the “empty” energy carriers return to the light-dependent reaction to obtain more energy. Figure 8.7 illustrates the components inside the chloroplast where the light-dependent and light-independent reactions take place. Link to Learning Click the link to learn more about photosynthesis. Everyday Connection Photosynthesis at the Grocery Store Major grocery stores in the United States are organized into departments, such as dairy, meats, produce, bread, cereals, and so forth. Each aisle ( Figure 8.8 ) contains hundreds, if not thousands, of different products for customers to buy and consume. Although there is a large variety, each item links back to photosynthesis. Meats and dairy link, because the animals were fed plant-based foods. The breads, cereals, and pastas come largely from starchy grains, which are the seeds of photosynthesis-dependent plants. What about desserts and drinks? All of these products contain sugar—sucrose is a plant product, a disaccharide, a carbohydrate molecule, which is built directly from photosynthesis. Moreover, many items are less obviously derived from plants: For instance, paper goods are generally plant products, and many plastics (abundant as products and packaging) are derived from algae. Virtually every spice and flavoring in the spice aisle was produced by a plant as a leaf, root, bark, flower, fruit, or stem. Ultimately, photosynthesis connects to every meal and every food a person consumes. 8.2 The Light-Dependent Reactions of Photosynthesis Learning Objectives By the end of this section, you will be able to: Explain how plants absorb energy from sunlight Describe short and long wavelengths of light Describe how and where photosynthesis takes place within a plant How can light be used to make food? When a person turns on a lamp, electrical energy becomes light energy. Like all other forms of kinetic energy, light can travel, change form, and be harnessed to do work. In the case of photosynthesis, light energy is converted into chemical energy, which photoautotrophs use to build carbohydrate molecules ( Figure 8.9 ). However, autotrophs only use a few specific components of sunlight. What Is Light Energy? The sun emits an enormous amount of electromagnetic radiation (solar energy). Humans can see only a fraction of this energy, which portion is therefore referred to as “visible light.” The manner in which solar energy travels is described as waves. Scientists can determine the amount of energy of a wave by measuring its wavelength , the distance between consecutive points of a wave. A single wave is measured from two consecutive points, such as from crest to crest or from trough to trough ( Figure 8.10 ). Visible light constitutes only one of many types of electromagnetic radiation emitted from the sun and other stars. Scientists differentiate the various types of radiant energy from the sun within the electromagnetic spectrum. The electromagnetic spectrum is the range of all possible frequencies of radiation ( Figure 8.11 ). The difference between wavelengths relates to the amount of energy carried by them. Each type of electromagnetic radiation travels at a particular wavelength. The longer the wavelength (or the more stretched out it appears in the diagram), the less energy is carried. Short, tight waves carry the most energy. This may seem illogical, but think of it in terms of a piece of moving a heavy rope. It takes little effort by a person to move a rope in long, wide waves. To make a rope move in short, tight waves, a person would need to apply significantly more energy. The electromagnetic spectrum ( Figure 8.11 ) shows several types of electromagnetic radiation originating from the sun, including X-rays and ultraviolet (UV) rays. The higher-energy waves can penetrate tissues and damage cells and DNA, explaining why both X-rays and UV rays can be harmful to living organisms. Absorption of Light Light energy initiates the process of photosynthesis when pigments absorb the light. Organic pigments, whether in the human retina or the chloroplast thylakoid, have a narrow range of energy levels that they can absorb. Energy levels lower than those represented by red light are insufficient to raise an orbital electron to a populatable, excited (quantum) state. Energy levels higher than those in blue light will physically tear the molecules apart, called bleaching. So retinal pigments can only “see” (absorb) 700 nm to 400 nm light, which is therefore called visible light. For the same reasons, plants pigment molecules absorb only light in the wavelength range of 700 nm to 400 nm; plant physiologists refer to this range for plants as photosynthetically active radiation. The visible light seen by humans as white light actually exists in a rainbow of colors. Certain objects, such as a prism or a drop of water, disperse white light to reveal the colors to the human eye. The visible light portion of the electromagnetic spectrum shows the rainbow of colors, with violet and blue having shorter wavelengths, and therefore higher energy. At the other end of the spectrum toward red, the wavelengths are longer and have lower energy ( Figure 8.12 ). Understanding Pigments Different kinds of pigments exist, and each has evolved to absorb only certain wavelengths (colors) of visible light. Pigments reflect or transmit the wavelengths they cannot absorb, making them appear in the corresponding color. Chlorophylls and carotenoids are the two major classes of photosynthetic pigments found in plants and algae; each class has multiple types of pigment molecules. There are five major chlorophylls: a , b , c and d and a related molecule found in prokaryotes called bacteriochlorophyll. Chlorophyll a and chlorophyll b are found in higher plant chloroplasts and will be the focus of the following discussion. With dozens of different forms, carotenoids are a much larger group of pigments. The carotenoids found in fruit—such as the red of tomato (lycopene), the yellow of corn seeds (zeaxanthin), or the orange of an orange peel (β-carotene)—are used as advertisements to attract seed dispersers. In photosynthesis, carotenoids function as photosynthetic pigments that are very efficient molecules for the disposal of excess energy. When a leaf is exposed to full sun, the light-dependent reactions are required to process an enormous amount of energy; if that energy is not handled properly, it can do significant damage. Therefore, many carotenoids reside in the thylakoid membrane, absorb excess energy, and safely dissipate that energy as heat. Each type of pigment can be identified by the specific pattern of wavelengths it absorbs from visible light, which is the absorption spectrum . The graph in Figure 8.13 shows the absorption spectra for chlorophyll a , chlorophyll b , and a type of carotenoid pigment called β-carotene (which absorbs blue and green light). Notice how each pigment has a distinct set of peaks and troughs, revealing a highly specific pattern of absorption. Chlorophyll a absorbs wavelengths from either end of the visible spectrum (blue and red), but not green. Because green is reflected or transmitted, chlorophyll appears green. Carotenoids absorb in the short-wavelength blue region, and reflect the longer yellow, red, and orange wavelengths. Many photosynthetic organisms have a mixture of pigments; using them, the organism can absorb energy from a wider range of wavelengths. Not all photosynthetic organisms have full access to sunlight. Some organisms grow underwater where light intensity and quality decrease and change with depth. Other organisms grow in competition for light. Plants on the rainforest floor must be able to absorb any bit of light that comes through, because the taller trees absorb most of the sunlight and scatter the remaining solar radiation ( Figure 8.14 ). When studying a photosynthetic organism, scientists can determine the types of pigments present by generating absorption spectra. An instrument called a spectrophotometer can differentiate which wavelengths of light a substance can absorb. Spectrophotometers measure transmitted light and compute from it the absorption. By extracting pigments from leaves and placing these samples into a spectrophotometer, scientists can identify which wavelengths of light an organism can absorb. Additional methods for the identification of plant pigments include various types of chromatography that separate the pigments by their relative affinities to solid and mobile phases. How Light-Dependent Reactions Work The overall function of light-dependent reactions is to convert solar energy into chemical energy in the form of NADPH and ATP. This chemical energy supports the light-independent reactions and fuels the assembly of sugar molecules. The light-dependent reactions are depicted in Figure 8.15 . Protein complexes and pigment molecules work together to produce NADPH and ATP. The actual step that converts light energy into chemical energy takes place in a multiprotein complex called a photosystem , two types of which are found embedded in the thylakoid membrane, photosystem II (PSII) and photosystem I (PSI) ( Figure 8.16 ). The two complexes differ on the basis of what they oxidize (that is, the source of the low-energy electron supply) and what they reduce (the place to which they deliver their energized electrons). Both photosystems have the same basic structure; a number of antenna proteins to which the chlorophyll molecules are bound surround the reaction center where the photochemistry takes place. Each photosystem is serviced by the light-harvesting complex , which passes energy from sunlight to the reaction center; it consists of multiple antenna proteins that contain a mixture of 300–400 chlorophyll a and b molecules as well as other pigments like carotenoids. The absorption of a single photon or distinct quantity or “packet” of light by any of the chlorophylls pushes that molecule into an excited state. In short, the light energy has now been captured by biological molecules but is not stored in any useful form yet. The energy is transferred from chlorophyll to chlorophyll until eventually (after about a millionth of a second), it is delivered to the reaction center. Up to this point, only energy has been transferred between molecules, not electrons. Visual Connection What is the initial source of electrons for the chloroplast electron transport chain? water oxygen carbon dioxide NADPH The reaction center contains a pair of chlorophyll a molecules with a special property. Those two chlorophylls can undergo oxidation upon excitation; they can actually give up an electron in a process called a photoact . It is at this step in the reaction center, this step in photosynthesis, that light energy is converted into an excited electron. All of the subsequent steps involve getting that electron onto the energy carrier NADPH for delivery to the Calvin cycle where the electron is deposited onto carbon for long-term storage in the form of a carbohydrate.PSII and PSI are two major components of the photosynthetic electron transport chain , which also includes the cytochrome complex . The cytochrome complex, an enzyme composed of two protein complexes, transfers the electrons from the carrier molecule plastoquinone (Pq) to the protein plastocyanin (Pc), thus enabling both the transfer of protons across the thylakoid membrane and the transfer of electrons from PSII to PSI. The reaction center of PSII (called P680 ) delivers its high-energy electrons, one at the time, to the primary electron acceptor , and through the electron transport chain (Pq to cytochrome complex to plastocyanine) to PSI. P680’s missing electron is replaced by extracting a low-energy electron from water; thus, water is split and PSII is re-reduced after every photoact. Splitting one H 2 O molecule releases two electrons, two hydrogen atoms, and one atom of oxygen. Splitting two molecules is required to form one molecule of diatomic O 2 gas. About 10 percent of the oxygen is used by mitochondria in the leaf to support oxidative phosphorylation. The remainder escapes to the atmosphere where it is used by aerobic organisms to support respiration. As electrons move through the proteins that reside between PSII and PSI, they lose energy. That energy is used to move hydrogen atoms from the stromal side of the membrane to the thylakoid lumen. Those hydrogen atoms, plus the ones produced by splitting water, accumulate in the thylakoid lumen and will be used synthesize ATP in a later step. Because the electrons have lost energy prior to their arrival at PSI, they must be re-energized by PSI, hence, another photon is absorbed by the PSI antenna. That energy is relayed to the PSI reaction center (called P700 ). P700 is oxidized and sends a high-energy electron to NADP + to form NADPH. Thus, PSII captures the energy to create proton gradients to make ATP, and PSI captures the energy to reduce NADP + into NADPH. The two photosystems work in concert, in part, to guarantee that the production of NADPH will roughly equal the production of ATP. Other mechanisms exist to fine tune that ratio to exactly match the chloroplast’s constantly changing energy needs. Generating an Energy Carrier: ATP As in the intermembrane space of the mitochondria during cellular respiration, the buildup of hydrogen ions inside the thylakoid lumen creates a concentration gradient. The passive diffusion of hydrogen ions from high concentration (in the thylakoid lumen) to low concentration (in the stroma) is harnessed to create ATP, just as in the electron transport chain of cellular respiration. The ions build up energy because of diffusion and because they all have the same electrical charge, repelling each other. To release this energy, hydrogen ions will rush through any opening, similar to water jetting through a hole in a dam. In the thylakoid, that opening is a passage through a specialized protein channel called the ATP synthase. The energy released by the hydrogen ion stream allows ATP synthase to attach a third phosphate group to ADP, which forms a molecule of ATP ( Figure 8.16 ). The flow of hydrogen ions through ATP synthase is called chemiosmosis because the ions move from an area of high to an area of low concentration through a semi-permeable structure. Link to Learning Watch this video to view the process of photosynthesis within a leaf. 8.3 Using Light Energy to Make Organic Molecules Learning Objectives By the end of this section, you will be able to: Describe the Calvin cycle Define carbon fixation Explain how photosynthesis works in the energy cycle of all living organisms After the energy from the sun is converted into chemical energy and temporarily stored in ATP and NADPH molecules, the cell has the fuel needed to build carbohydrate molecules for long-term energy storage. The products of the light-dependent reactions, ATP and NADPH, have lifespans in the range of millionths of seconds, whereas the products of the light-independent reactions (carbohydrates and other forms of reduced carbon) can survive for hundreds of millions of years. The carbohydrate molecules made will have a backbone of carbon atoms. Where does the carbon come from? It comes from carbon dioxide, the gas that is a waste product of respiration in microbes, fungi, plants, and animals. The Calvin Cycle In plants, carbon dioxide (CO 2 ) enters the leaves through stomata, where it diffuses over short distances through intercellular spaces until it reaches the mesophyll cells. Once in the mesophyll cells, CO 2 diffuses into the stroma of the chloroplast—the site of light-independent reactions of photosynthesis. These reactions actually have several names associated with them. Another term, the Calvin cycle , is named for the man who discovered it, and because these reactions function as a cycle. Others call it the Calvin-Benson cycle to include the name of another scientist involved in its discovery. The most outdated name is dark reactions, because light is not directly required ( Figure 8.17 ). However, the term dark reaction can be misleading because it implies incorrectly that the reaction only occurs at night or is independent of light, which is why most scientists and instructors no longer use it. The light-independent reactions of the Calvin cycle can be organized into three basic stages: fixation, reduction, and regeneration. Stage 1: Fixation In the stroma, in addition to CO 2 , two other components are present to initiate the light-independent reactions: an enzyme called ribulose-1,5-bisphosphate carboxylase/oxygenase (RuBisCO), and three molecules of ribulose bisphosphate (RuBP), as shown in Figure 8.18 . RuBP has five atoms of carbon, flanked by two phosphates. Visual Connection Which of the following statements is true? In photosynthesis, oxygen, carbon dioxide, ATP, and NADPH are reactants. GA3P and water are products. In photosynthesis, chlorophyll, water, and carbon dioxide are reactants. GA3P and oxygen are products. In photosynthesis, water, carbon dioxide, ATP, and NADPH are reactants. RuBP and oxygen are products. In photosynthesis, water and carbon dioxide are reactants. GA3P and oxygen are products. RuBisCO catalyzes a reaction between CO 2 and RuBP. For each CO 2 molecule that reacts with one RuBP, two molecules of another compound (3-PGA) form. PGA has three carbons and one phosphate. Each turn of the cycle involves only one RuBP and one carbon dioxide and forms two molecules of 3-PGA. The number of carbon atoms remains the same, as the atoms move to form new bonds during the reactions (3 atoms from 3CO 2 + 15 atoms from 3RuBP = 18 atoms in 3 atoms of 3-PGA). This process is called carbon fixation , because CO 2 is “fixed” from an inorganic form into organic molecules. Stage 2: Reduction ATP and NADPH are used to convert the six molecules of 3-PGA into six molecules of a chemical called glyceraldehyde 3-phosphate (G3P). That is a reduction reaction because it involves the gain of electrons by 3-PGA. Recall that a reduction is the gain of an electron by an atom or molecule. Six molecules of both ATP and NADPH are used. For ATP, energy is released with the loss of the terminal phosphate atom, converting it into ADP; for NADPH, both energy and a hydrogen atom are lost, converting it into NADP + . Both of these molecules return to the nearby light-dependent reactions to be reused and reenergized. Stage 3: Regeneration Interestingly, at this point, only one of the G3P molecules leaves the Calvin cycle and is sent to the cytoplasm to contribute to the formation of other compounds needed by the plant. Because the G3P exported from the chloroplast has three carbon atoms, it takes three “turns” of the Calvin cycle to fix enough net carbon to export one G3P. But each turn makes two G3Ps, thus three turns make six G3Ps. One is exported while the remaining five G3P molecules remain in the cycle and are used to regenerate RuBP, which enables the system to prepare for more CO 2 to be fixed. Three more molecules of ATP are used in these regeneration reactions. Link to Learning This link leads to an animation of the Calvin cycle. Click stage 1, stage 2, and then stage 3 to see G3P and ATP regenerate to form RuBP. Evolution Connection Photosynthesis During the evolution of photosynthesis, a major shift occurred from the bacterial type of photosynthesis that involves only one photosystem and is typically anoxygenic (does not generate oxygen) into modern oxygenic (does generate oxygen) photosynthesis, employing two photosystems. This modern oxygenic photosynthesis is used by many organisms—from giant tropical leaves in the rainforest to tiny cyanobacterial cells—and the process and components of this photosynthesis remain largely the same. Photosystems absorb light and use electron transport chains to convert energy into the chemical energy of ATP and NADH. The subsequent light-independent reactions then assemble carbohydrate molecules with this energy. Photosynthesis in desert plants has evolved adaptations that conserve water. In the harsh dry heat, every drop of water must be used to survive. Because stomata must open to allow for the uptake of CO 2 , water escapes from the leaf during active photosynthesis. Desert plants have evolved processes to conserve water and deal with harsh conditions. A more efficient use of CO 2 allows plants to adapt to living with less water. Some plants such as cacti ( Figure 8.19 ) can prepare materials for photosynthesis during the night by a temporary carbon fixation/storage process, because opening the stomata at this time conserves water due to cooler temperatures. In addition, cacti have evolved the ability to carry out low levels of photosynthesis without opening stomata at all, an extreme mechanism to face extremely dry periods. The Energy Cycle Whether the organism is a bacterium, plant, or animal, all living things access energy by breaking down carbohydrate molecules. But if plants make carbohydrate molecules, why would they need to break them down, especially when it has been shown that the gas organisms release as a “waste product” (CO 2 ) acts as a substrate for the formation of more food in photosynthesis? Remember, living things need energy to perform life functions. In addition, an organism can either make its own food or eat another organism—either way, the food still needs to be broken down. Finally, in the process of breaking down food, called cellular respiration, heterotrophs release needed energy and produce “waste” in the form of CO 2 gas. In nature, there is no such thing as waste. Every single atom of matter and energy is conserved, recycling over and over infinitely. Substances change form or move from one type of molecule to another, but their constituent atoms never disappear ( Figure 8.20 ). CO 2 is no more a form of waste than oxygen is wasteful to photosynthesis. Both are byproducts of reactions that move on to other reactions. Photosynthesis absorbs light energy to build carbohydrates in chloroplasts, and aerobic cellular respiration releases energy by using oxygen to metabolize carbohydrates in the cytoplasm and mitochondria. Both processes use electron transport chains to capture the energy necessary to drive other reactions. These two powerhouse processes, photosynthesis and cellular respiration, function in biological, cyclical harmony to allow organisms to access life-sustaining energy that originates millions of miles away in a burning star humans call the sun.
business_law_i_essentials
Chapter Outline 13.1 Introduction to International Law 13.2 Sources and Practice of International Law Introduction Learning Outcome Explain international law and its role in business.
[ { "answer": { "ans_choice": 2, "ans_text": "Both a and b." }, "bloom": null, "hl_context": "<hl> The second important clause related to international law is the Treaty Clause , which states that the president has the power “ by and with the advice and consent of the senate ” to create treaties with other nations ( Clarkson , Miller , & Cross , 2018 , p . 440 ) . <hl> This clause restricts treaties to federal authority , meaning that states do not have the power to enter a treaty with another nation . For example , the United States and Mexico can sign a treaty to reduce trade barriers between both nations , but the state of Texas cannot sign a treaty with Mexico to reduce trade barriers between Texas businesses and Mexico . Additionally , any treaties established with other countries become U . S . law , and any conflicting law is null and void . <hl> There are two important clauses in the U . S . Constitution related to international law . <hl> First , the Foreign Commerce Clause enables Congress to “ regulate commerce with foreign nations ” ( Cheeseman , 2016 , p . 904 ) . This clause permits U . S . businesses to actively negotiate and implement taxes or other regulations as they relate to international commerce . However , businesses cannot unduly burden foreign commerce . For example , General Motors , which is based in Michigan , cannot suggest that the state impose a 50 percent tax on foreign-made automobiles sold in the state , while not imposing the same tax on U . S . - made vehicles . Michigan can , however , impose a 10 percent tax on all automobile sales in the state to offset the costs of foreign trade and commerce .", "hl_sentences": "The second important clause related to international law is the Treaty Clause , which states that the president has the power “ by and with the advice and consent of the senate ” to create treaties with other nations ( Clarkson , Miller , & Cross , 2018 , p . 440 ) . There are two important clauses in the U . S . Constitution related to international law .", "question": { "cloze_format": "___ is/are clauses in the U.S. Constitution that are relate to international law.", "normal_format": "What are clauses in the U.S. Constitution that relate to international law?", "question_choices": [ "Treaty Clause.", "Foreign Commerce Clause.", "Both a and b.", "Neither a nor b." ], "question_id": "fs-2232531356", "question_text": "The following are clauses in the U.S. Constitution that relate to international law." }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 0, "ans_text": "a" }, "bloom": null, "hl_context": "<hl> The UN Security Council includes five permanent members and 10 countries selected by the General Assembly to serve two-year terms . <hl> The five countries that hold permanent membership are China , France , Russia , the United Kingdom , and the United States ( Cheeseman , 2016 , p . 558 ) . This Council is primarily responsible for overseeing global peace and security measures . The World Bank is a UN organization , financed by contributions from developed countries and headquartered in Washington , D . C . Its primary functions include providing money to developing countries to fund projects that relieve suffering , including building roads and dams , establishing hospitals , developing agriculture , and other humanitarian efforts . The World Bank provides both grants and long-term low interest rate loans to countries , often granting debt relief for outstanding loans ( Cheeseman , 2016 , p . 559 ) .", "hl_sentences": "The UN Security Council includes five permanent members and 10 countries selected by the General Assembly to serve two-year terms .", "question": { "cloze_format": "The types of companies that must register with the SEC are ___ .", "normal_format": "Which types of companies must register with the SEC?", "question_choices": [ "5 members and 10 countries.", "10 members and 5 countries.", "10 members and 10 countries.", "5 members and 5 countries." ], "question_id": "fs-223531356", "question_text": "The UN Security Council is made up of:" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 3, "ans_text": "Customs, treaties, and organizations." }, "bloom": null, "hl_context": "<hl> The sources of international law are customs , treaties , and organizations , as discussed in the previous section . <hl> These three components work synergistically to influence how the international community facilitates business trade and commerce . More importantly , international law is enforced when a country violates the principles set forth by globally shared customs , treaties , and organizations . <hl> International law is primarily governed by customs , treaties , and organizations that influence how laws are understood , interpreted , and enforced around the world . <hl> Since there is not a central court to enforce international law , each country utilizes its own courts to settle disputes . Collective action , reciprocity , and shaming are three examples of non-legislative methods that influence trade when enacted against nations that violate international law .", "hl_sentences": "The sources of international law are customs , treaties , and organizations , as discussed in the previous section . International law is primarily governed by customs , treaties , and organizations that influence how laws are understood , interpreted , and enforced around the world .", "question": { "cloze_format": "___ is not considered a report required by the Securities Exchange Act of 1934.", "normal_format": "All of the following are considered reports required by the Securities Exchange Act of 1934 except which one?", "question_choices": [ "Customs, treaties, and laws.", "Customs, treaties, and edict.", "Treaties, laws, and edicts.", "Customs, treaties, and organizations." ], "question_id": "fs-22325313560", "question_text": "Sources of international law include:" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 1, "ans_text": "b" }, "bloom": null, "hl_context": "<hl> One of the most important governing documents for international law is the United Nations Convention on Contracts for the International Sale of Goods ( CISG ) , which was established in 1980 . <hl> This law governs contracts of countries that have ratified it as the priority contract for trade . <hl> By January 2018 , 84 countries had adopted CISG , including the countries that account for more than two-thirds of all global trade . <hl> Those countries include the United States , Canada , China , Japan , Mexico , Argentina , Brazil , and most European countries . The CISG is enforced whenever international transactions occur without the presence of written contracts to govern those transactions . There are limits to the CISG , however , as the CISG does not apply to consumer sales or contracts for services ( Clarkson , Miller , & Cross , 2018 , p . 376 ) .", "hl_sentences": "One of the most important governing documents for international law is the United Nations Convention on Contracts for the International Sale of Goods ( CISG ) , which was established in 1980 . By January 2018 , 84 countries had adopted CISG , including the countries that account for more than two-thirds of all global trade .", "question": { "cloze_format": "___ countries have adopted the United Nations Convention on Contracts for the International Sale of Goods (CISG).", "normal_format": "How many countries have adopted the United Nations Convention on Contracts for the International Sale of Goods (CISG)?", "question_choices": [ "74.", "84.", "94.", "104." ], "question_id": "fs-2235313560", "question_text": "How many countries have adopted the United Nations Convention on Contracts for the International Sale of Goods (CISG)?" }, "references_are_paraphrase": null } ]
13
13.1 Introduction to International Law In 1945, President Harry Truman stated, “When Kansas and Colorado have a quarrel over the water in the Arkansas River they don’t call out the National Guard in each state and go to war over it. They bring a suit in the Supreme Court of the United States and abide by the decision. There isn’t a reason in the world why we cannot do that internationally” (Cheeseman, 2016, p. 903). Customs, which vary among global communities and international organizations, are a primary reason why the world cannot pursue such an answer to trade and commerce dealings. The priorities and aims for Chinese businesses differ from those of Brazil. Each of those two countries have radically different business perspectives from the United States. For this reason, international law utilizes customs, treaties, and organizations to guide relationships among nations, with the goal of allowing each country as much leverage as possible over its own business dealings. International Law International law relates to the policies and procedures that govern relationships among nations (Clarkson, Miller, & Cross, 2018). These are crucial for businesses for multiple reasons. First, there is not a single authoritative legislative source for global business affairs, nor a single world court responsible for interpreting international law (Cheeseman, 2016, p. 903). There is also not a global executive branch that enforces international law, which leaves global business affairs particularly vulnerable. Secondly, if a nation violates an international law and persuasive tactics fail, then the countries that were violated, or international organizations tasked with overseeing global trade, may act. Often these actions use force to correct the offenses and may include economic sanctions, severance of diplomatic relations, boycotts, or even war against the offending nation (Clarkson, Miller, & Cross, 2018, p. 439). The purpose of international laws is to permit countries as much authority as possible over their own international business affairs, while maximizing economic benefits of trade and working relationships with other nations. Since many countries have historically allowed governance by international agreements when conducting global business, there exists an evolving body of international laws that facilitate global trade and commerce. U.S. Constitutional Clauses There are two important clauses in the U.S. Constitution related to international law. First, the Foreign Commerce Clause enables Congress to “regulate commerce with foreign nations” (Cheeseman, 2016, p. 904). This clause permits U.S. businesses to actively negotiate and implement taxes or other regulations as they relate to international commerce. However, businesses cannot unduly burden foreign commerce. For example, General Motors, which is based in Michigan, cannot suggest that the state impose a 50 percent tax on foreign-made automobiles sold in the state, while not imposing the same tax on U.S.-made vehicles. Michigan can, however, impose a 10 percent tax on all automobile sales in the state to offset the costs of foreign trade and commerce. The second important clause related to international law is the Treaty Clause , which states that the president has the power “by and with the advice and consent of the senate” to create treaties with other nations (Clarkson, Miller, & Cross, 2018, p. 440). This clause restricts treaties to federal authority, meaning that states do not have the power to enter a treaty with another nation. For example, the United States and Mexico can sign a treaty to reduce trade barriers between both nations, but the state of Texas cannot sign a treaty with Mexico to reduce trade barriers between Texas businesses and Mexico. Additionally, any treaties established with other countries become U.S. law, and any conflicting law is null and void. Primary Sources of International Law International customs, treaties, and organizations are the primary sources of international law (Clarkson, Miller, & Cross, 2018, p. 439). These three components work together to guide how nations understand, define, and interpret international laws that govern global business affairs. International Customs Customs are general practices between nations that guide their business relationships. According to the Statute of the International Court of Justice, international customs are “accepted as law” (Clarkson, Miller, & Cross, 2018, p. 439). While customary international law (CIL) is not written, nor does it require ratification to become binding, CIL nonetheless provides guidelines for how nations conduct business affairs (Bradley & Gulati, 2010, p. 204). One example of a custom is the international protection of ambassadors. For thousands of years, ambassadors have been protected while serving diplomatic missions. For this reason, countries protect foreign ambassadors with the understanding that any harm caused to ambassadors would be a violation of international law. International Treaties Treaties and other agreements between nations are authorized and ratified by the countries that acknowledge their legality. There are two different types of agreements: bilateral, which is formed by two nations; and multilateral, which is formed by several nations. The Peru-United States Trade Promotion Agreement is an example of a bilateral agreement. It was signed in 2006, ratified by Peru the same year, and ratified by the United States in 2007. This bilateral agreement is considered beneficial to the United States because it improves access to Peruvian goods, while promoting security and democracy in the South American country. The North American Free Trade Agreement, or NAFTA, is an example of a multilateral agreement. It was ratified in 1994, when Mexico joined the previous trade agreement between the United States and Canada. In September 2018, the Trump administration successfully completed re-negotiations with Mexico and Canada that lasted over one year. Among other aims, these negotiations worked to increase auto industry wages for workers in Mexico and modify pharmaceutical regulations with Canada. International Organizations International organizations are comprised of officials who represent member nations that have established a treaty to oversee shared interests, including trade and commerce. The U.S. participates in more than 120 bilateral and multilateral organizations around the world. International organizations adopt resolutions that standardize behavior and create uniform rules related to trade and commerce. Two of the most significant international organizations established in the twentieth century that significantly impact U.S. trade and commerce are the United Nations and the European Union. United Nations The United Nations (UN) was created as a multilateral treaty in 1945. The UN’s organizational goals include maintaining global peace and security, promoting economic and social cooperation, and protecting human rights, especially related to women and children (Cheeseman, 2016, p. 905). The UN General Assembly includes representatives from each member nation. As of 2018, the UN acknowledges 195 sovereign states, with all but two participating as full members. These two, Palestine and the Vatican City, are classified as “observer states.” Six additional countries are not UN members, but are recognized as a country by at least one UN member country: Abkhazia, Kosovo, Northern Cypress, South Ossetia, Taiwan, and Western Sahara. The UN Security Council includes five permanent members and 10 countries selected by the General Assembly to serve two-year terms. The five countries that hold permanent membership are China, France, Russia, the United Kingdom, and the United States (Cheeseman, 2016, p. 558). This Council is primarily responsible for overseeing global peace and security measures. The World Bank is a UN organization, financed by contributions from developed countries and headquartered in Washington, D.C. Its primary functions include providing money to developing countries to fund projects that relieve suffering, including building roads and dams, establishing hospitals, developing agriculture, and other humanitarian efforts. The World Bank provides both grants and long-term low interest rate loans to countries, often granting debt relief for outstanding loans (Cheeseman, 2016, p. 559). The United Nations Commission International Trade Law is one of the most important international organizations to date, establishing the 1980 Convention on Contracts for the International Sale of Goods (CISG), which will be discussed further in the next section. European Union The European Union (EU) is a regional international organization that includes many countries in Europe. It was established to create peace across the region and promote economic, social, and cultural development (Cheeseman, 2016, p. 561). As of 2018, there are 28 countries affiliated with the EU, although the United Kingdom has begun steps to withdraw its membership. Additionally, Macedonia is actively seeking a path toward EU membership, although as of September 2018, the country’s citizens remain divided. The EU organization has established a treaty for its members that creates open borders for trade among member nations, especially for capital, labor, goods, and services. The impact on U.S. commerce is significant, as the EU represents more than 500 million people and a gross community product that exceeds that of the United States, Canada, and Mexico combined (Cheeseman, 2016, p. 561). Sovereignty National sovereignty defines a nation. While clearly defined borders and independent governments also set parameters for a nation, sovereignty is an important legal principle that allows nations to enter negotiated treaties with other countries and honor territorial boundaries. It is among the most important international law principles, thus greatly impacting international trade and commerce. Since the 1800s, most established nations allowed for absolute sovereignty among the global community. However, by the 1940s, that allowance was significantly reduced, as countries revisited sovereignty in light of globalization, transportation, and communication advances, and the rise of international organizations (Goldsmith, 2000, p. 959). Consequentially, doctrines of limited immunity were created that established guidelines for how countries may prosecute, or hold foreign nationals accountable, during international trade and commerce dealings. A doctrine of sovereign immunity states that countries are granted immunity from lawsuits in courts of other countries (p. 569). Although the United States initially granted absolute immunity to foreign governments from lawsuits in U.S. courts, in 1952, the United States adapted federal law to qualified immunity, which is the immunity regulation adopted in most Western nations. This law led to the Foreign Sovereign Immunities Act of 1976 , allowing U.S. governance over lawsuits against other nations in the United States in either federal- or state-level courts. Simply stated, a foreign country is not immune to lawsuits in the United States when the country has waived its immunity, or if the commercial activity against which the lawsuit is intended causes a direct effect in the United States. 13.2 Sources and Practice of International Law International law is primarily governed by customs, treaties, and organizations that influence how laws are understood, interpreted, and enforced around the world. Since there is not a central court to enforce international law, each country utilizes its own courts to settle disputes. Collective action, reciprocity, and shaming are three examples of non-legislative methods that influence trade when enacted against nations that violate international law. Sources of International Law The sources of international law are customs, treaties, and organizations, as discussed in the previous section. These three components work synergistically to influence how the international community facilitates business trade and commerce. More importantly, international law is enforced when a country violates the principles set forth by globally shared customs, treaties, and organizations. One of the most important governing documents for international law is the United Nations Convention on Contracts for the International Sale of Goods (CISG) , which was established in 1980. This law governs contracts of countries that have ratified it as the priority contract for trade. By January 2018, 84 countries had adopted CISG, including the countries that account for more than two-thirds of all global trade. Those countries include the United States, Canada, China, Japan, Mexico, Argentina, Brazil, and most European countries. The CISG is enforced whenever international transactions occur without the presence of written contracts to govern those transactions. There are limits to the CISG, however, as the CISG does not apply to consumer sales or contracts for services (Clarkson, Miller, & Cross, 2018, p. 376). International Principles and Doctrines There are three significant principles that help establish and enforce international law: the Principle of Comity, the Act of State Doctrine, and the Doctrine of Sovereign Immunity. The Principle of Comity states that nations will defer to the laws and decrees of other nations when those laws are consistent with their own, essentially upholding reciprocity between nations with similar laws. For example, a U.S. court will most likely uphold a business contract as valid even if it was drafted in England, since the United Kingdom’s legal procedures are consistent with U.S. procedures (Cross & Miller, 2018, p. 216). The Act of State Doctrine is a law applicable in England and the United States. It states that these two nations will not pass legal judgement on public acts committed by a recognized government if those acts occur within that government’s own territory (Cross & Miller, 2018, p. 216). For example, the United States will not file a lawsuit against Petrobras, a Brazilian oil company, alleging price fixing, since the act of pricing oil occurs in Brazil, which is a nation that holds control over its own natural resources. The Doctrine of Sovereign Immunity , which was introduced in the previous section, states that foreign nations are immune from U.S. jurisdiction when certain circumstances are applied. However, there are exceptions to this law. If a foreign country conducts commercial business activity in the United States and an entity in the United States files a lawsuit against the foreign business, then the foreign state is not immune from U.S. jurisdiction (Cross & Miller, 2018, p. 216). International Law Enforcement One of the most important considerations for international business is understanding that companies operating in foreign nations are subject to the laws of those nations (Cross & Miller, 2018, p. 212). When international laws are violated, disputes are often resolved through the legal systems within individual nations. Most countries have either common law or civil law systems. Common law systems operate independently by developing their own rules that govern areas of business law, such as torts and contracts. The United States has a common law system. One-third of all people in the world live in nations in which common law is practiced. Civil law systems base their legislation on Roman civil law, which utilizes statutory codes as the primary source of law (p. 212). Common Law Civil Law Australia Malaysia Argentina Indonesia Bangladesh New Zealand Austria Iran Canada Nigeria Brazil Italy Ghana Singapore Chile Japan India United Kingdom China Mexico Israel United States Egypt Poland Jamaica Zambia Finland South Korea Kenya France Sweden Germany Tunisia Greece Venezuela Table 13.1 Impact on International Trade There are three international law enforcement methods that can radically impact trade: collective action, reciprocity, and shaming. Collective action occurs when businesses work collectively to strengthen their resources and achieve a shared goal. In February 2018, the UN Conference on Trade and Development Secretary-General argued that collective action can be one of the most effective methods for protecting international trade in the current global climate. Due to recent trade restructuring from the United States and the United Kingdom (pending its withdrawal from the EU), collective action was promoted as a way to “harness energy that will not fragment the [international trade] system” (UNCTAD, 2018). By leveraging nations to defend “rules-based multilateral trading systems as a force for creating inclusive prosperity,” the Secretary-General promoted collective action as the primary way to assure continued international peace and economic viability for generations to come. Reciprocity is central to international trade and at the core of CIL. It happens most commonly in international business exchanges as countries lower import duties, or other trade barriers, in exchange for mutual arrangements extended by the other country. Reciprocity can be beneficial to the nations involved, or it can be punitive. In 2016, presidential candidate Donald Trump campaigned for an international trade climate that would produce fairer options for the United States. Since his inauguration, he has increasingly pressured the global community by imposing taxes on imports from Canada, China, the EU, and Mexico, each of which has retaliated in reciprocity. In 2018, China accused the United States of launching the “largest trade war in economic history,” of which the final global impacts remain largely unknown (BBC, 2018). Shaming is a deliberate attempt to negatively impact a state, regime, or governmental leader’s reputation by publicizing and targeting violations of international laws, including customary norms, treaty breaches, and violations of organizational expectations (Gopalan & Fuller, 2014, p. 75). However, shaming is not viewed as particularly effective without more concrete measures to accompany it (Klymak, 2017). A recent research study conducted by the Department of Economics in Dublin, Ireland, found that there is no evidence to suggest that there has been a decrease in the imports of goods to the United States from countries where foreign goods are likely produced by child and forced labor. Despite media coverage and the International Labour Organization’s coverage that routinely shames certain nations for producing goods by child or forced labor, those goods are nonetheless regularly imported for international sale.
biology
Chapter Outline 16.1 Regulation of Gene Expression 16.2 Prokaryotic Gene Regulation 16.3 Eukaryotic Epigenetic Gene Regulation 16.4 Eukaryotic Transcription Gene Regulation 16.5 Eukaryotic Post-transcriptional Gene Regulation 16.6 Eukaryotic Translational and Post-translational Gene Regulation 16.7 Cancer and Gene Regulation Introduction Each somatic cell in the body generally contains the same DNA. A few exceptions include red blood cells, which contain no DNA in their mature state, and some immune system cells that rearrange their DNA while producing antibodies. In general, however, the genes that determine whether you have green eyes, brown hair, and how fast you metabolize food are the same in the cells in your eyes and your liver, even though these organs function quite differently. If each cell has the same DNA, how is it that cells or organs are different? Why do cells in the eye differ so dramatically from cells in the liver? Whereas each cell shares the same genome and DNA sequence, each cell does not turn on, or express, the same set of genes. Each cell type needs a different set of proteins to perform its function. Therefore, only a small subset of proteins is expressed in a cell. For the proteins to be expressed, the DNA must be transcribed into RNA and the RNA must be translated into protein. In a given cell type, not all genes encoded in the DNA are transcribed into RNA or translated into protein because specific cells in our body have specific functions. Specialized proteins that make up the eye (iris, lens, and cornea) are only expressed in the eye, whereas the specialized proteins in the heart (pacemaker cells, heart muscle, and valves) are only expressed in the heart. At any given time, only a subset of all of the genes encoded by our DNA are expressed and translated into proteins. The expression of specific genes is a highly regulated process with many levels and stages of control. This complexity ensures the proper expression in the proper cell at the proper time.
[ { "answer": { "ans_choice": 3, "ans_text": "epigenetic, transcriptional, post-transcriptional, translational, and post-translational levels" }, "bloom": "2", "hl_context": "Cancer can be described as a disease of altered gene expression . There are many proteins that are turned on or off ( gene activation or gene silencing ) that dramatically alter the overall activity of the cell . <hl> A gene that is not normally expressed in that cell can be switched on and expressed at high levels . <hl> <hl> This can be the result of gene mutation or changes in gene regulation ( epigenetic , transcription , post-transcription , translation , or post-translation ) . <hl> <hl> Gene expression is regulated primarily at the transcriptional level Gene expression is regulated at many levels ( epigenetic , transcriptional , nuclear shuttling , post-transcriptional , translational , and post-translational ) <hl>", "hl_sentences": "A gene that is not normally expressed in that cell can be switched on and expressed at high levels . This can be the result of gene mutation or changes in gene regulation ( epigenetic , transcription , post-transcription , translation , or post-translation ) . Gene expression is regulated primarily at the transcriptional level Gene expression is regulated at many levels ( epigenetic , transcriptional , nuclear shuttling , post-transcriptional , translational , and post-translational )", "question": { "cloze_format": "The level(s) at which control of gene expression in eukaryotic cells occurs, is/are ___.", "normal_format": "Control of gene expression in eukaryotic cells occurs at which level(s)?", "question_choices": [ "only the transcriptional level", "epigenetic and transcriptional levels", "epigenetic, transcriptional, and translational levels", "epigenetic, transcriptional, post-transcriptional, translational, and post-translational levels" ], "question_id": "fs-id2187777", "question_text": "Control of gene expression in eukaryotic cells occurs at which level(s)?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 1, "ans_text": "regulation of gene expression after translation" }, "bloom": null, "hl_context": "<hl> Changes in epigenetic regulation , transcription , RNA stability , protein translation , and post-translational control can be detected in cancer . <hl> While these changes don ’ t occur simultaneously in one cancer , changes at each of these levels can be detected when observing cancer at different sites in different individuals . Therefore , changes in histone acetylation ( epigenetic modification that leads to gene silencing ) , activation of transcription factors by phosphorylation , increased RNA stability , increased translational control , and protein modification can all be detected at some point in various cancer cells . Scientists are working to understand the common changes that give rise to certain types of cancer or how a modification might be exploited to destroy a tumor cell . Cancer can be described as a disease of altered gene expression . There are many proteins that are turned on or off ( gene activation or gene silencing ) that dramatically alter the overall activity of the cell . <hl> A gene that is not normally expressed in that cell can be switched on and expressed at high levels . <hl> <hl> This can be the result of gene mutation or changes in gene regulation ( epigenetic , transcription , post-transcription , translation , or post-translation ) . <hl>", "hl_sentences": "Changes in epigenetic regulation , transcription , RNA stability , protein translation , and post-translational control can be detected in cancer . A gene that is not normally expressed in that cell can be switched on and expressed at high levels . This can be the result of gene mutation or changes in gene regulation ( epigenetic , transcription , post-transcription , translation , or post-translation ) .", "question": { "cloze_format": "The location where a large percentage of e-waste wind up is ___ .", "normal_format": "What does post-translational control refer to?", "question_choices": [ "regulation of gene expression after transcription", "regulation of gene expression after translation", "control of epigenetic activation", "period between transcription and translation" ], "question_id": "fs-id1472236", "question_text": "Post-translational control refers to:" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 1, "ans_text": "repressed" }, "bloom": null, "hl_context": "<hl> The lac Operon : An Inducer Operon The third type of gene regulation in prokaryotic cells occurs through inducible operons , which have proteins that bind to activate or repress transcription depending on the local environment and the needs of the cell . <hl> The lac operon is a typical inducible operon . As mentioned previously , E . coli is able to use other sugars as energy sources when glucose concentrations are low . To do so , the cAMP – CAP protein complex serves as a positive regulator to induce transcription . One such sugar source is lactose . The lac operon encodes the genes necessary to acquire and process the lactose from the local environment . CAP binds to the operator sequence upstream of the promoter that initiates transcription of the lac operon . However , for the lac operon to be activated , two conditions must be met . First , the level of glucose must be very low or non-existent . <hl> Second , lactose must be present . <hl> <hl> Only when glucose is absent and lactose is present will the lac operon be transcribed ( Figure 16.5 ) . <hl> This makes sense for the cell , because it would be energetically wasteful to create the proteins to process lactose if glucose was plentiful or lactose was not available .", "hl_sentences": "The lac Operon : An Inducer Operon The third type of gene regulation in prokaryotic cells occurs through inducible operons , which have proteins that bind to activate or repress transcription depending on the local environment and the needs of the cell . Second , lactose must be present . Only when glucose is absent and lactose is present will the lac operon be transcribed ( Figure 16.5 ) .", "question": { "cloze_format": "If glucose is absent, but so is lactose, the lac operon will be ________.", "normal_format": "If glucose is absent, but so is lactose, what happens to the lac operon?", "question_choices": [ "activated", "repressed", "activated, but only partially", "mutated" ], "question_id": "fs-idm153813744", "question_text": "If glucose is absent, but so is lactose, the lac operon will be ________." }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 3, "ans_text": "b and c are both true" }, "bloom": null, "hl_context": "<hl> Prokaryotic organisms are single-celled organisms that lack a cell nucleus , and their DNA therefore floats freely in the cell cytoplasm . <hl> <hl> To synthesize a protein , the processes of transcription and translation occur almost simultaneously . <hl> <hl> When the resulting protein is no longer needed , transcription stops . <hl> <hl> As a result , the primary method to control what type of protein and how much of each protein is expressed in a prokaryotic cell is the regulation of DNA transcription . <hl> All of the subsequent steps occur automatically . When more protein is required , more transcription occurs . Therefore , in prokaryotic cells , the control of gene expression is mostly at the transcriptional level .", "hl_sentences": "Prokaryotic organisms are single-celled organisms that lack a cell nucleus , and their DNA therefore floats freely in the cell cytoplasm . To synthesize a protein , the processes of transcription and translation occur almost simultaneously . When the resulting protein is no longer needed , transcription stops . As a result , the primary method to control what type of protein and how much of each protein is expressed in a prokaryotic cell is the regulation of DNA transcription .", "question": { "cloze_format": "Prokaryotic cells lack a nucleus. Therefore, the genes in prokaryotic cells are ___.", "normal_format": "Prokaryotic cells lack a nucleus. Therefore, Which genes are in prokaryotic cells?", "question_choices": [ "all expressed, all of the time", "transcribed and translated almost simultaneously", "transcriptionally controlled because translation begins before transcription ends", "b and c are both true" ], "question_id": "fs-idm98160192", "question_text": "Prokaryotic cells lack a nucleus. Therefore, the genes in prokaryotic cells are:" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 0, "ans_text": "the addition of reversible changes to histone proteins and DNA" }, "bloom": "3", "hl_context": "<hl> Silencing genes through epigenetic mechanisms is also very common in cancer cells . <hl> <hl> There are characteristic modifications to histone proteins and DNA that are associated with silenced genes . <hl> In cancer cells , the DNA in the promoter region of silenced genes is methylated on cytosine DNA residues in CpG islands . Histone proteins that surround that region lack the acetylation modification that is present when the genes are expressed in normal cells . This combination of DNA methylation and histone deacetylation ( epigenetic modifications that lead to gene silencing ) is commonly found in cancer . When these modifications occur , the gene present in that chromosomal region is silenced . Increasingly , scientists understand how epigenetic changes are altered in cancer . Because these changes are temporary and can be reversed — for example , by preventing the action of the histone deacetylase protein that removes acetyl groups , or by DNA methyl transferase enzymes that add methyl groups to cytosines in DNA — it is possible to design new drugs and new therapies to take advantage of the reversible nature of these processes . Indeed , many researchers are testing how a silenced gene can be switched back on in a cancer cell to help re-establish normal growth patterns . <hl> This type of gene regulation is called epigenetic regulation . <hl> <hl> Epigenetic means “ around genetics . ” The changes that occur to the histone proteins and DNA do not alter the nucleotide sequence and are not permanent . <hl> Instead , these changes are temporary ( although they often persist through multiple rounds of cell division ) and alter the chromosomal structure ( open or closed ) as needed . A gene can be turned on or off depending upon the location and modifications to the histone proteins and DNA . If a gene is to be transcribed , the histone proteins and DNA are modified surrounding the chromosomal region encoding that gene . This opens the chromosomal region to allow access for RNA polymerase and other proteins , called transcription factors , to bind to the promoter region , located just upstream of the gene , and initiate transcription . If a gene is to remain turned off , or silenced , the histone proteins and DNA have different modifications that signal a closed chromosomal configuration . In this closed configuration , the RNA polymerase and transcription factors do not have access to the DNA and transcription cannot occur ( Figure 16.7 ) .", "hl_sentences": "Silencing genes through epigenetic mechanisms is also very common in cancer cells . There are characteristic modifications to histone proteins and DNA that are associated with silenced genes . This type of gene regulation is called epigenetic regulation . Epigenetic means “ around genetics . ” The changes that occur to the histone proteins and DNA do not alter the nucleotide sequence and are not permanent .", "question": { "cloze_format": "Epigenetic modifications is (the) ___.", "normal_format": "What are epigenetic modifications?", "question_choices": [ "the addition of reversible changes to histone proteins and DNA", "the removal of nucleosomes from the DNA", "the addition of more nucleosomes to the DNA", "mutation of the DNA sequence" ], "question_id": "fs-id3112360", "question_text": "What are epigenetic modifications?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 3, "ans_text": "all of the above" }, "bloom": "3", "hl_context": "Silencing genes through epigenetic mechanisms is also very common in cancer cells . There are characteristic modifications to histone proteins and DNA that are associated with silenced genes . In cancer cells , the DNA in the promoter region of silenced genes is methylated on cytosine DNA residues in CpG islands . Histone proteins that surround that region lack the acetylation modification that is present when the genes are expressed in normal cells . This combination of DNA methylation and histone deacetylation ( epigenetic modifications that lead to gene silencing ) is commonly found in cancer . When these modifications occur , the gene present in that chromosomal region is silenced . <hl> Increasingly , scientists understand how epigenetic changes are altered in cancer . <hl> <hl> Because these changes are temporary and can be reversed — for example , by preventing the action of the histone deacetylase protein that removes acetyl groups , or by DNA methyl transferase enzymes that add methyl groups to cytosines in DNA — it is possible to design new drugs and new therapies to take advantage of the reversible nature of these processes . <hl> Indeed , many researchers are testing how a silenced gene can be switched back on in a cancer cell to help re-establish normal growth patterns . This type of gene regulation is called epigenetic regulation . <hl> Epigenetic means “ around genetics . ” The changes that occur to the histone proteins and DNA do not alter the nucleotide sequence and are not permanent . <hl> Instead , these changes are temporary ( although they often persist through multiple rounds of cell division ) and alter the chromosomal structure ( open or closed ) as needed . <hl> A gene can be turned on or off depending upon the location and modifications to the histone proteins and DNA . <hl> <hl> If a gene is to be transcribed , the histone proteins and DNA are modified surrounding the chromosomal region encoding that gene . <hl> This opens the chromosomal region to allow access for RNA polymerase and other proteins , called transcription factors , to bind to the promoter region , located just upstream of the gene , and initiate transcription . If a gene is to remain turned off , or silenced , the histone proteins and DNA have different modifications that signal a closed chromosomal configuration . In this closed configuration , the RNA polymerase and transcription factors do not have access to the DNA and transcription cannot occur ( Figure 16.7 ) .", "hl_sentences": "Increasingly , scientists understand how epigenetic changes are altered in cancer . Because these changes are temporary and can be reversed — for example , by preventing the action of the histone deacetylase protein that removes acetyl groups , or by DNA methyl transferase enzymes that add methyl groups to cytosines in DNA — it is possible to design new drugs and new therapies to take advantage of the reversible nature of these processes . Epigenetic means “ around genetics . ” The changes that occur to the histone proteins and DNA do not alter the nucleotide sequence and are not permanent . A gene can be turned on or off depending upon the location and modifications to the histone proteins and DNA . If a gene is to be transcribed , the histone proteins and DNA are modified surrounding the chromosomal region encoding that gene .", "question": { "cloze_format": "The statement about epigenetic changes that is true is that ___.", "normal_format": "Which of the following are true of epigenetic changes?", "question_choices": [ "allow DNA to be transcribed", "move histones to open or close a chromosomal region", "are temporary", "all of the above" ], "question_id": "fs-id2072168", "question_text": "Which of the following are true of epigenetic changes?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 2, "ans_text": "RNA polymerase" }, "bloom": null, "hl_context": "Like prokaryotic cells , the transcription of genes in eukaryotes requires the actions of an RNA polymerase to bind to a sequence upstream of a gene to initiate transcription . <hl> However , unlike prokaryotic cells , the eukaryotic RNA polymerase requires other proteins , or transcription factors , to facilitate transcription initiation . <hl> Transcription factors are proteins that bind to the promoter sequence and other regulatory sequences to control the transcription of the target gene . RNA polymerase by itself cannot initiate transcription in eukaryotic cells . Transcription factors must bind to the promoter region first and recruit RNA polymerase to the site for transcription to be established . A DNA sequence that codes for proteins is referred to as the coding region . The five coding regions for the tryptophan biosynthesis enzymes are arranged sequentially on the chromosome in the operon . Just before the coding region is the transcriptional start site . <hl> This is the region of DNA to which RNA polymerase binds to initiate transcription . <hl> The promoter sequence is upstream of the transcriptional start site ; each operon has a sequence within or near the promoter to which proteins ( activators or repressors ) can bind and regulate transcription .", "hl_sentences": "However , unlike prokaryotic cells , the eukaryotic RNA polymerase requires other proteins , or transcription factors , to facilitate transcription initiation . This is the region of DNA to which RNA polymerase binds to initiate transcription .", "question": { "cloze_format": "The binding of ________ is required for transcription to start.", "normal_format": "The binding of which is required for transcription to start?", "question_choices": [ "a protein", "DNA polymerase", "RNA polymerase", "a transcription factor" ], "question_id": "fs-id1808039", "question_text": "The binding of ________ is required for transcription to start." }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 1, "ans_text": "increased transcription of a distant gene" }, "bloom": "3", "hl_context": "Alterations in cells that give rise to cancer can affect the transcriptional control of gene expression . Mutations that activate transcription factors , such as increased phosphorylation , can increase the binding of a transcription factor to its binding site in a promoter . This could lead to increased transcriptional activation of that gene that results in modified cell growth . <hl> Alternatively , a mutation in the DNA of a promoter or enhancer region can increase the binding ability of a transcription factor . <hl> <hl> This could also lead to the increased transcription and aberrant gene expression that is seen in cancer cells . <hl>", "hl_sentences": "Alternatively , a mutation in the DNA of a promoter or enhancer region can increase the binding ability of a transcription factor . This could also lead to the increased transcription and aberrant gene expression that is seen in cancer cells .", "question": { "cloze_format": "The result from the binding of a transcription factor to an enhancer region is a(n) ___ .", "normal_format": "What will result from the binding of a transcription factor to an enhancer region?", "question_choices": [ "decreased transcription of an adjacent gene", "increased transcription of a distant gene", "alteration of the translation of an adjacent gene", "initiation of the recruitment of RNA polymerase" ], "question_id": "fs-id1394736", "question_text": "What will result from the binding of a transcription factor to an enhancer region?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 3, "ans_text": "all of the above" }, "bloom": "2", "hl_context": "Chemical modifications occur in response to external stimuli such as stress , the lack of nutrients , heat , or ultraviolet light exposure . These changes can alter epigenetic accessibility , transcription , mRNA stability , or translation — all resulting in changes in expression of various genes . This is an efficient way for the cell to rapidly change the levels of specific proteins in response to the environment . <hl> Because proteins are involved in every stage of gene regulation , the phosphorylation of a protein ( depending on the protein that is modified ) can alter accessibility to the chromosome , can alter translation ( by altering transcription factor binding or function ) , can change nuclear shuttling ( by influencing modifications to the nuclear pore complex ) , can alter RNA stability ( by binding or not binding to the RNA to regulate its stability ) , can modify translation ( increase or decrease ) , or can change post-translational modifications ( add or remove phosphates or other chemical modifications ) . <hl> <hl> Control of RNA Stability <hl> <hl> RNA splicing , the first stage of post-transcriptional control In eukaryotic cells , the RNA transcript often contains regions , called introns , that are removed prior to translation . <hl> The regions of RNA that code for protein are called exons ( Figure 16.10 ) . After an RNA molecule has been transcribed , but prior to its departure from the nucleus to be translated , the RNA is processed and the introns are removed by splicing . Evolution Connection Alternative RNA Splicing RNA is transcribed , but must be processed into a mature form before translation can begin . <hl> This processing after an RNA molecule has been transcribed , but before it is translated into a protein , is called post-transcriptional modification . <hl> As with the epigenetic and transcriptional stages of processing , this post-transcriptional step can also be regulated to control gene expression in the cell . If the RNA is not processed , shuttled , or translated , then no protein will be synthesized .", "hl_sentences": "Because proteins are involved in every stage of gene regulation , the phosphorylation of a protein ( depending on the protein that is modified ) can alter accessibility to the chromosome , can alter translation ( by altering transcription factor binding or function ) , can change nuclear shuttling ( by influencing modifications to the nuclear pore complex ) , can alter RNA stability ( by binding or not binding to the RNA to regulate its stability ) , can modify translation ( increase or decrease ) , or can change post-translational modifications ( add or remove phosphates or other chemical modifications ) . Control of RNA Stability RNA splicing , the first stage of post-transcriptional control In eukaryotic cells , the RNA transcript often contains regions , called introns , that are removed prior to translation . This processing after an RNA molecule has been transcribed , but before it is translated into a protein , is called post-transcriptional modification .", "question": { "cloze_format": "___ is involved in post-transcriptional control.", "normal_format": "Which of the following are involved in post-transcriptional control?", "question_choices": [ "control of RNA splicing", "control of RNA shuttling", "control of RNA stability", "all of the above" ], "question_id": "fs-id2685625", "question_text": "Which of the following are involved in post-transcriptional control?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 3, "ans_text": "either increase or decrease" }, "bloom": null, "hl_context": "<hl> In addition to RBPs that bind to and control ( increase or decrease ) RNA stability , other elements called microRNAs can bind to the RNA molecule . <hl> These microRNAs , or miRNAs , are short RNA molecules that are only 21 – 24 nucleotides in length . The miRNAs are made in the nucleus as longer pre-miRNAs . These pre-miRNAs are chopped into mature miRNAs by a protein called dicer . Like transcription factors and RBPs , mature miRNAs recognize a specific sequence and bind to the RNA ; however , miRNAs also associate with a ribonucleoprotein complex called the RNA-induced silencing complex ( RISC ) . RISC binds along with the miRNA to degrade the target mRNA . Together , miRNAs and the RISC complex rapidly destroy the RNA molecule . 16.6 Eukaryotic Translational and Post-translational Gene Regulation Learning Objectives By the end of this section , you will be able to : Before the mRNA leaves the nucleus , it is given two protective \" caps \" that prevent the end of the strand from degrading during its journey . The 5 ' cap , which is placed on the 5 ' end of the mRNA , is usually composed of a methylated guanosine triphosphate molecule ( GTP ) . The poly-A tail , which is attached to the 3 ' end , is usually composed of a series of adenine nucleotides . Once the RNA is transported to the cytoplasm , the length of time that the RNA resides there can be controlled . Each RNA molecule has a defined lifespan and decays at a specific rate . This rate of decay can influence how much protein is in the cell . If the decay rate is increased , the RNA will not exist in the cytoplasm as long , shortening the time for translation to occur . Conversely , if the rate of decay is decreased , the RNA molecule will reside in the cytoplasm longer and more protein can be translated . This rate of decay is referred to as the RNA stability . If the RNA is stable , it will be detected for longer periods of time in the cytoplasm . Binding of proteins to the RNA can influence its stability . <hl> Proteins , called RNA-binding proteins , or RBPs , can bind to the regions of the RNA just upstream or downstream of the protein-coding region . <hl> These regions in the RNA that are not translated into protein are called the untranslated regions , or UTRs . They are not introns ( those have been removed in the nucleus ) . Rather , these are regions that regulate mRNA localization , stability , and protein translation . The region just before the protein-coding region is called the 5 ' UTR , whereas the region after the coding region is called the 3 ' UTR ( Figure 16.12 ) . <hl> The binding of RBPs to these regions can increase or decrease the stability of an RNA molecule , depending on the specific RBP that binds . <hl>", "hl_sentences": "In addition to RBPs that bind to and control ( increase or decrease ) RNA stability , other elements called microRNAs can bind to the RNA molecule . Proteins , called RNA-binding proteins , or RBPs , can bind to the regions of the RNA just upstream or downstream of the protein-coding region . The binding of RBPs to these regions can increase or decrease the stability of an RNA molecule , depending on the specific RBP that binds .", "question": { "cloze_format": "Binding of an RNA binding protein will ________ the stability of the RNA molecule.", "normal_format": "Which effect will the binding of an RNA binding protein have on the stability of the RNA molecule?", "question_choices": [ "increase", "decrease", "neither increase nor decrease", "either increase or decrease" ], "question_id": "fs-id685962", "question_text": "Binding of an RNA binding protein will ________ the stability of the RNA molecule." }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 0, "ans_text": "protein function" }, "bloom": "3", "hl_context": "<hl> There are many examples of how translational or post-translational modifications of proteins arise in cancer . <hl> <hl> Modifications are found in cancer cells from the increased translation of a protein to changes in protein phosphorylation to alternative splice variants of a protein . <hl> An example of how the expression of an alternative form of a protein can have dramatically different outcomes is seen in colon cancer cells . The c-Flip protein , a protein involved in mediating the cell death pathway , comes in two forms : long ( c-FLIPL ) and short ( c-FLIPS ) . Both forms appear to be involved in initiating controlled cell death mechanisms in normal cells . However , in colon cancer cells , expression of the long form results in increased cell growth instead of cell death . Clearly , the expression of the wrong protein dramatically alters cell function and contributes to the development of cancer .", "hl_sentences": "There are many examples of how translational or post-translational modifications of proteins arise in cancer . Modifications are found in cancer cells from the increased translation of a protein to changes in protein phosphorylation to alternative splice variants of a protein .", "question": { "cloze_format": "Post-translational modifications of proteins can affect ___ .", "normal_format": "Post-translational modifications of proteins can affect which of the following?", "question_choices": [ "protein function", "transcriptional regulation", "chromatin modification", "all of the above" ], "question_id": "fs-id1404412", "question_text": "Post-translational modifications of proteins can affect which of the following?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 2, "ans_text": "oncogenes" }, "bloom": null, "hl_context": "<hl> Proto-oncogenes are positive cell-cycle regulators . <hl> <hl> When mutated , proto-oncogenes can become oncogenes and cause cancer . <hl> <hl> Overexpression of the oncogene can lead to uncontrolled cell growth . <hl> <hl> This is because oncogenes can alter transcriptional activity , stability , or protein translation of another gene that directly or indirectly controls cell growth . <hl> An example of an oncogene involved in cancer is a protein called myc . Myc is a transcription factor that is aberrantly activated in Burkett ’ s Lymphoma , a cancer of the lymph system . Overexpression of myc transforms normal B cells into cancerous cells that continue to grow uncontrollably . High B-cell numbers can result in tumors that can interfere with normal bodily function . Patients with Burkett ’ s lymphoma can develop tumors on their jaw or in their mouth that interfere with the ability to eat .", "hl_sentences": "Proto-oncogenes are positive cell-cycle regulators . When mutated , proto-oncogenes can become oncogenes and cause cancer . Overexpression of the oncogene can lead to uncontrolled cell growth . This is because oncogenes can alter transcriptional activity , stability , or protein translation of another gene that directly or indirectly controls cell growth .", "question": { "cloze_format": "Cancer causing genes are called ________.", "normal_format": "What are cancer causing genes called?", "question_choices": [ "transformation genes", "tumor suppressor genes", "oncogenes", "mutated genes" ], "question_id": "fs-id1674486", "question_text": "Cancer causing genes are called ________." }, "references_are_paraphrase": null } ]
16
16.1 Regulation of Gene Expression Learning Objectives By the end of this section, you will be able to: Discuss why every cell does not express all of its genes Describe how prokaryotic gene regulation occurs at the transcriptional level Discuss how eukaryotic gene regulation occurs at the epigenetic, transcriptional, post-transcriptional, translational, and post-translational levels For a cell to function properly, necessary proteins must be synthesized at the proper time. All cells control or regulate the synthesis of proteins from information encoded in their DNA. The process of turning on a gene to produce RNA and protein is called gene expression . Whether in a simple unicellular organism or a complex multi-cellular organism, each cell controls when and how its genes are expressed. For this to occur, there must be a mechanism to control when a gene is expressed to make RNA and protein, how much of the protein is made, and when it is time to stop making that protein because it is no longer needed. The regulation of gene expression conserves energy and space. It would require a significant amount of energy for an organism to express every gene at all times, so it is more energy efficient to turn on the genes only when they are required. In addition, only expressing a subset of genes in each cell saves space because DNA must be unwound from its tightly coiled structure to transcribe and translate the DNA. Cells would have to be enormous if every protein were expressed in every cell all the time. The control of gene expression is extremely complex. Malfunctions in this process are detrimental to the cell and can lead to the development of many diseases, including cancer. Prokaryotic versus Eukaryotic Gene Expression To understand how gene expression is regulated, we must first understand how a gene codes for a functional protein in a cell. The process occurs in both prokaryotic and eukaryotic cells, just in slightly different manners. Prokaryotic organisms are single-celled organisms that lack a cell nucleus, and their DNA therefore floats freely in the cell cytoplasm. To synthesize a protein, the processes of transcription and translation occur almost simultaneously. When the resulting protein is no longer needed, transcription stops. As a result, the primary method to control what type of protein and how much of each protein is expressed in a prokaryotic cell is the regulation of DNA transcription. All of the subsequent steps occur automatically. When more protein is required, more transcription occurs. Therefore, in prokaryotic cells, the control of gene expression is mostly at the transcriptional level. Eukaryotic cells, in contrast, have intracellular organelles that add to their complexity. In eukaryotic cells, the DNA is contained inside the cell’s nucleus and there it is transcribed into RNA. The newly synthesized RNA is then transported out of the nucleus into the cytoplasm, where ribosomes translate the RNA into protein. The processes of transcription and translation are physically separated by the nuclear membrane; transcription occurs only within the nucleus, and translation occurs only outside the nucleus in the cytoplasm. The regulation of gene expression can occur at all stages of the process ( Figure 16.2 ). Regulation may occur when the DNA is uncoiled and loosened from nucleosomes to bind transcription factors ( epigenetic level), when the RNA is transcribed (transcriptional level), when the RNA is processed and exported to the cytoplasm after it is transcribed ( post-transcriptional level), when the RNA is translated into protein (translational level), or after the protein has been made ( post-translational level). The differences in the regulation of gene expression between prokaryotes and eukaryotes are summarized in Table 16.1 . The regulation of gene expression is discussed in detail in subsequent modules. Differences in the Regulation of Gene Expression of Prokaryotic and Eukaryotic Organisms Prokaryotic organisms Eukaryotic organisms Lack nucleus Contain nucleus DNA is found in the cytoplasm DNA is confined to the nuclear compartment RNA transcription and protein formation occur almost simultaneously RNA transcription occurs prior to protein formation, and it takes place in the nucleus. Translation of RNA to protein occurs in the cytoplasm. Gene expression is regulated primarily at the transcriptional level Gene expression is regulated at many levels (epigenetic, transcriptional, nuclear shuttling, post-transcriptional, translational, and post-translational) Table 16.1 Evolution Connection Evolution of Gene Regulation Prokaryotic cells can only regulate gene expression by controlling the amount of transcription. As eukaryotic cells evolved, the complexity of the control of gene expression increased. For example, with the evolution of eukaryotic cells came compartmentalization of important cellular components and cellular processes. A nuclear region that contains the DNA was formed. Transcription and translation were physically separated into two different cellular compartments. It therefore became possible to control gene expression by regulating transcription in the nucleus, and also by controlling the RNA levels and protein translation present outside the nucleus. Some cellular processes arose from the need of the organism to defend itself. Cellular processes such as gene silencing developed to protect the cell from viral or parasitic infections. If the cell could quickly shut off gene expression for a short period of time, it would be able to survive an infection when other organisms could not. Therefore, the organism evolved a new process that helped it survive, and it was able to pass this new development to offspring. 16.2 Prokaryotic Gene Regulation Learning Objectives By the end of this section, you will be able to: Describe the steps involved in prokaryotic gene regulation Explain the roles of activators, inducers, and repressors in gene regulation The DNA of prokaryotes is organized into a circular chromosome supercoiled in the nucleoid region of the cell cytoplasm. Proteins that are needed for a specific function, or that are involved in the same biochemical pathway, are encoded together in blocks called operons . For example, all of the genes needed to use lactose as an energy source are coded next to each other in the lactose (or lac ) operon. In prokaryotic cells, there are three types of regulatory molecules that can affect the expression of operons: repressors, activators, and inducers. Repressors are proteins that suppress transcription of a gene in response to an external stimulus, whereas activators are proteins that increase the transcription of a gene in response to an external stimulus. Finally, inducers are small molecules that either activate or repress transcription depending on the needs of the cell and the availability of substrate. The trp Operon: A Repressor Operon Bacteria such as E. coli need amino acids to survive. Tryptophan is one such amino acid that E. coli can ingest from the environment. E. coli can also synthesize tryptophan using enzymes that are encoded by five genes. These five genes are next to each other in what is called the tryptophan ( trp ) operon ( Figure 16.3 ). If tryptophan is present in the environment, then E. coli does not need to synthesize it and the switch controlling the activation of the genes in the trp operon is switched off. However, when tryptophan availability is low, the switch controlling the operon is turned on, transcription is initiated, the genes are expressed, and tryptophan is synthesized. A DNA sequence that codes for proteins is referred to as the coding region. The five coding regions for the tryptophan biosynthesis enzymes are arranged sequentially on the chromosome in the operon. Just before the coding region is the transcriptional start site . This is the region of DNA to which RNA polymerase binds to initiate transcription. The promoter sequence is upstream of the transcriptional start site; each operon has a sequence within or near the promoter to which proteins (activators or repressors) can bind and regulate transcription. A DNA sequence called the operator sequence is encoded between the promoter region and the first trp coding gene. This operator contains the DNA code to which the repressor protein can bind. When tryptophan is present in the cell, two tryptophan molecules bind to the trp repressor, which changes shape to bind to the trp operator. Binding of the tryptophan–repressor complex at the operator physically prevents the RNA polymerase from binding, and transcribing the downstream genes. When tryptophan is not present in the cell, the repressor by itself does not bind to the operator; therefore, the operon is active and tryptophan is synthesized. Because the repressor protein actively binds to the operator to keep the genes turned off, the trp operon is negatively regulated and the proteins that bind to the operator to silence trp expression are negative regulators . Link to Learning Watch this video to learn more about the trp operon. Click to view content Catabolite Activator Protein (CAP): An Activator Regulator Just as the trp operon is negatively regulated by tryptophan molecules, there are proteins that bind to the operator sequences that act as a positive regulator to turn genes on and activate them. For example, when glucose is scarce, E. coli bacteria can turn to other sugar sources for fuel. To do this, new genes to process these alternate genes must be transcribed. When glucose levels drop, cyclic AMP (cAMP) begins to accumulate in the cell. The cAMP molecule is a signaling molecule that is involved in glucose and energy metabolism in E. coli . When glucose levels decline in the cell, accumulating cAMP binds to the positive regulator catabolite activator protein (CAP) , a protein that binds to the promoters of operons that control the processing of alternative sugars. When cAMP binds to CAP, the complex binds to the promoter region of the genes that are needed to use the alternate sugar sources ( Figure 16.4 ). In these operons, a CAP binding site is located upstream of the RNA polymerase binding site in the promoter. This increases the binding ability of RNA polymerase to the promoter region and the transcription of the genes. The lac Operon: An Inducer Operon The third type of gene regulation in prokaryotic cells occurs through inducible operons , which have proteins that bind to activate or repress transcription depending on the local environment and the needs of the cell. The lac operon is a typical inducible operon. As mentioned previously, E. coli is able to use other sugars as energy sources when glucose concentrations are low. To do so, the cAMP–CAP protein complex serves as a positive regulator to induce transcription. One such sugar source is lactose. The lac operon encodes the genes necessary to acquire and process the lactose from the local environment. CAP binds to the operator sequence upstream of the promoter that initiates transcription of the lac operon. However, for the lac operon to be activated, two conditions must be met. First, the level of glucose must be very low or non-existent. Second, lactose must be present. Only when glucose is absent and lactose is present will the lac operon be transcribed ( Figure 16.5 ). This makes sense for the cell, because it would be energetically wasteful to create the proteins to process lactose if glucose was plentiful or lactose was not available. Visual Connection In E. coli , the trp operon is on by default, while the lac operon is off. Why do you think this is the case? If glucose is absent, then CAP can bind to the operator sequence to activate transcription. If lactose is absent, then the repressor binds to the operator to prevent transcription. If either of these requirements is met, then transcription remains off. Only when both conditions are satisfied is the lac operon transcribed ( Table 16.2 ). Signals that Induce or Repress Transcription of the lac Operon Glucose CAP binds Lactose Repressor binds Transcription + - - + No + - + - Some - + - + No - + + - Yes Table 16.2 Link to Learning Watch an animated tutorial about the workings of lac operon here. Click to view content 16.3 Eukaryotic Epigenetic Gene Regulation Learning Objectives By the end of this section, you will be able to: Explain the process of epigenetic regulation Describe how access to DNA is controlled by histone modification Eukaryotic gene expression is more complex than prokaryotic gene expression because the processes of transcription and translation are physically separated. Unlike prokaryotic cells, eukaryotic cells can regulate gene expression at many different levels. Eukaryotic gene expression begins with control of access to the DNA. This form of regulation, called epigenetic regulation, occurs even before transcription is initiated. Epigenetic Control: Regulating Access to Genes within the Chromosome The human genome encodes over 20,000 genes; each of the 23 pairs of human chromosomes encodes thousands of genes. The DNA in the nucleus is precisely wound, folded, and compacted into chromosomes so that it will fit into the nucleus. It is also organized so that specific segments can be accessed as needed by a specific cell type. The first level of organization, or packing, is the winding of DNA strands around histone proteins. Histones package and order DNA into structural units called nucleosome complexes, which can control the access of proteins to the DNA regions ( Figure 16.6 a ). Under the electron microscope, this winding of DNA around histone proteins to form nucleosomes looks like small beads on a string ( Figure 16.6 b ). These beads (histone proteins) can move along the string (DNA) and change the structure of the molecule. If DNA encoding a specific gene is to be transcribed into RNA, the nucleosomes surrounding that region of DNA can slide down the DNA to open that specific chromosomal region and allow for the transcriptional machinery (RNA polymerase) to initiate transcription ( Figure 16.7 ). Nucleosomes can move to open the chromosome structure to expose a segment of DNA, but do so in a very controlled manner. Visual Connection In females, one of the two X chromosomes is inactivated during embryonic development because of epigenetic changes to the chromatin. What impact do you think these changes would have on nucleosome packing? How the histone proteins move is dependent on signals found on both the histone proteins and on the DNA. These signals are tags added to histone proteins and DNA that tell the histones if a chromosomal region should be open or closed ( Figure 16.8 depicts modifications to histone proteins and DNA). These tags are not permanent, but may be added or removed as needed. They are chemical modifications (phosphate, methyl, or acetyl groups) that are attached to specific amino acids in the protein or to the nucleotides of the DNA. The tags do not alter the DNA base sequence, but they do alter how tightly wound the DNA is around the histone proteins. DNA is a negatively charged molecule; therefore, changes in the charge of the histone will change how tightly wound the DNA molecule will be. When unmodified, the histone proteins have a large positive charge; by adding chemical modifications like acetyl groups, the charge becomes less positive. The DNA molecule itself can also be modified. This occurs within very specific regions called CpG islands. These are stretches with a high frequency of cytosine and guanine dinucleotide DNA pairs (CG) found in the promoter regions of genes. When this configuration exists, the cytosine member of the pair can be methylated (a methyl group is added). This modification changes how the DNA interacts with proteins, including the histone proteins that control access to the region. Highly methylated (hypermethylated) DNA regions with deacetylated histones are tightly coiled and transcriptionally inactive. This type of gene regulation is called epigenetic regulation. Epigenetic means “around genetics.” The changes that occur to the histone proteins and DNA do not alter the nucleotide sequence and are not permanent. Instead, these changes are temporary (although they often persist through multiple rounds of cell division) and alter the chromosomal structure (open or closed) as needed. A gene can be turned on or off depending upon the location and modifications to the histone proteins and DNA. If a gene is to be transcribed, the histone proteins and DNA are modified surrounding the chromosomal region encoding that gene. This opens the chromosomal region to allow access for RNA polymerase and other proteins, called transcription factors , to bind to the promoter region, located just upstream of the gene, and initiate transcription. If a gene is to remain turned off, or silenced, the histone proteins and DNA have different modifications that signal a closed chromosomal configuration. In this closed configuration, the RNA polymerase and transcription factors do not have access to the DNA and transcription cannot occur ( Figure 16.7 ). Link to Learning View this video that describes how epigenetic regulation controls gene expression. Click to view content 16.4 Eukaryotic Transcription Gene Regulation Learning Objectives By the end of this section, you will be able to: Discuss the role of transcription factors in gene regulation Explain how enhancers and repressors regulate gene expression Like prokaryotic cells, the transcription of genes in eukaryotes requires the actions of an RNA polymerase to bind to a sequence upstream of a gene to initiate transcription. However, unlike prokaryotic cells, the eukaryotic RNA polymerase requires other proteins, or transcription factors, to facilitate transcription initiation. Transcription factors are proteins that bind to the promoter sequence and other regulatory sequences to control the transcription of the target gene. RNA polymerase by itself cannot initiate transcription in eukaryotic cells. Transcription factors must bind to the promoter region first and recruit RNA polymerase to the site for transcription to be established. Link to Learning View the process of transcription—the making of RNA from a DNA template. Click to view content The Promoter and the Transcription Machinery Genes are organized to make the control of gene expression easier. The promoter region is immediately upstream of the coding sequence. This region can be short (only a few nucleotides in length) or quite long (hundreds of nucleotides long). The longer the promoter, the more available space for proteins to bind. This also adds more control to the transcription process. The length of the promoter is gene-specific and can differ dramatically between genes. Consequently, the level of control of gene expression can also differ quite dramatically between genes. The purpose of the promoter is to bind transcription factors that control the initiation of transcription. Within the promoter region, just upstream of the transcriptional start site, resides the TATA box. This box is simply a repeat of thymine and adenine dinucleotides (literally, TATA repeats). RNA polymerase binds to the transcription initiation complex, allowing transcription to occur. To initiate transcription, a transcription factor (TFIID) is the first to bind to the TATA box. Binding of TFIID recruits other transcription factors, including TFIIB, TFIIE, TFIIF, and TFIIH to the TATA box. Once this complex is assembled, RNA polymerase can bind to its upstream sequence. When bound along with the transcription factors, RNA polymerase is phosphorylated. This releases part of the protein from the DNA to activate the transcription initiation complex and places RNA polymerase in the correct orientation to begin transcription; DNA-bending protein brings the enhancer, which can be quite a distance from the gene, in contact with transcription factors and mediator proteins ( Figure 16.9 ). In addition to the general transcription factors, other transcription factors can bind to the promoter to regulate gene transcription. These transcription factors bind to the promoters of a specific set of genes. They are not general transcription factors that bind to every promoter complex, but are recruited to a specific sequence on the promoter of a specific gene. There are hundreds of transcription factors in a cell that each bind specifically to a particular DNA sequence motif. When transcription factors bind to the promoter just upstream of the encoded gene, it is referred to as a cis -acting element , because it is on the same chromosome just next to the gene. The region that a particular transcription factor binds to is called the transcription factor binding site . Transcription factors respond to environmental stimuli that cause the proteins to find their binding sites and initiate transcription of the gene that is needed. Enhancers and Transcription In some eukaryotic genes, there are regions that help increase or enhance transcription. These regions, called enhancers , are not necessarily close to the genes they enhance. They can be located upstream of a gene, within the coding region of the gene, downstream of a gene, or may be thousands of nucleotides away. Enhancer regions are binding sequences, or sites, for transcription factors. When a DNA-bending protein binds, the shape of the DNA changes ( Figure 16.9 ). This shape change allows for the interaction of the activators bound to the enhancers with the transcription factors bound to the promoter region and the RNA polymerase. Whereas DNA is generally depicted as a straight line in two dimensions, it is actually a three-dimensional object. Therefore, a nucleotide sequence thousands of nucleotides away can fold over and interact with a specific promoter. Turning Genes Off: Transcriptional Repressors Like prokaryotic cells, eukaryotic cells also have mechanisms to prevent transcription. Transcriptional repressors can bind to promoter or enhancer regions and block transcription. Like the transcriptional activators, repressors respond to external stimuli to prevent the binding of activating transcription factors. 16.5 Eukaryotic Post-transcriptional Gene Regulation Learning Objectives By the end of this section, you will be able to: Understand RNA splicing and explain its role in regulating gene expression Describe the importance of RNA stability in gene regulation RNA is transcribed, but must be processed into a mature form before translation can begin. This processing after an RNA molecule has been transcribed, but before it is translated into a protein, is called post-transcriptional modification. As with the epigenetic and transcriptional stages of processing, this post-transcriptional step can also be regulated to control gene expression in the cell. If the RNA is not processed, shuttled, or translated, then no protein will be synthesized. RNA splicing, the first stage of post-transcriptional control In eukaryotic cells, the RNA transcript often contains regions, called introns, that are removed prior to translation. The regions of RNA that code for protein are called exons ( Figure 16.10 ). After an RNA molecule has been transcribed, but prior to its departure from the nucleus to be translated, the RNA is processed and the introns are removed by splicing. Evolution Connection Alternative RNA Splicing In the 1970s, genes were first observed that exhibited alternative RNA splicing. Alternative RNA splicing is a mechanism that allows different protein products to be produced from one gene when different combinations of introns, and sometimes exons, are removed from the transcript ( Figure 16.11 ). This alternative splicing can be haphazard, but more often it is controlled and acts as a mechanism of gene regulation, with the frequency of different splicing alternatives controlled by the cell as a way to control the production of different protein products in different cells or at different stages of development. Alternative splicing is now understood to be a common mechanism of gene regulation in eukaryotes; according to one estimate, 70 percent of genes in humans are expressed as multiple proteins through alternative splicing. How could alternative splicing evolve? Introns have a beginning and ending recognition sequence; it is easy to imagine the failure of the splicing mechanism to identify the end of an intron and instead find the end of the next intron, thus removing two introns and the intervening exon. In fact, there are mechanisms in place to prevent such intron skipping, but mutations are likely to lead to their failure. Such “mistakes” would more than likely produce a nonfunctional protein. Indeed, the cause of many genetic diseases is alternative splicing rather than mutations in a sequence. However, alternative splicing would create a protein variant without the loss of the original protein, opening up possibilities for adaptation of the new variant to new functions. Gene duplication has played an important role in the evolution of new functions in a similar way by providing genes that may evolve without eliminating the original, functional protein. Link to Learning Visualize how mRNA splicing happens by watching the process in action in this video. Click to view content Control of RNA Stability Before the mRNA leaves the nucleus, it is given two protective "caps" that prevent the end of the strand from degrading during its journey. The 5' cap , which is placed on the 5' end of the mRNA, is usually composed of a methylated guanosine triphosphate molecule (GTP). The poly-A tail , which is attached to the 3' end, is usually composed of a series of adenine nucleotides. Once the RNA is transported to the cytoplasm, the length of time that the RNA resides there can be controlled. Each RNA molecule has a defined lifespan and decays at a specific rate. This rate of decay can influence how much protein is in the cell. If the decay rate is increased, the RNA will not exist in the cytoplasm as long, shortening the time for translation to occur. Conversely, if the rate of decay is decreased, the RNA molecule will reside in the cytoplasm longer and more protein can be translated. This rate of decay is referred to as the RNA stability. If the RNA is stable, it will be detected for longer periods of time in the cytoplasm. Binding of proteins to the RNA can influence its stability. Proteins, called RNA-binding proteins , or RBPs, can bind to the regions of the RNA just upstream or downstream of the protein-coding region. These regions in the RNA that are not translated into protein are called the untranslated regions , or UTRs. They are not introns (those have been removed in the nucleus). Rather, these are regions that regulate mRNA localization, stability, and protein translation. The region just before the protein-coding region is called the 5' UTR , whereas the region after the coding region is called the 3' UTR ( Figure 16.12 ). The binding of RBPs to these regions can increase or decrease the stability of an RNA molecule, depending on the specific RBP that binds. RNA Stability and microRNAs In addition to RBPs that bind to and control (increase or decrease) RNA stability, other elements called microRNAs can bind to the RNA molecule. These microRNAs , or miRNAs, are short RNA molecules that are only 21–24 nucleotides in length. The miRNAs are made in the nucleus as longer pre-miRNAs. These pre-miRNAs are chopped into mature miRNAs by a protein called dicer . Like transcription factors and RBPs, mature miRNAs recognize a specific sequence and bind to the RNA; however, miRNAs also associate with a ribonucleoprotein complex called the RNA-induced silencing complex (RISC) . RISC binds along with the miRNA to degrade the target mRNA. Together, miRNAs and the RISC complex rapidly destroy the RNA molecule. 16.6 Eukaryotic Translational and Post-translational Gene Regulation Learning Objectives By the end of this section, you will be able to: Understand the process of translation and discuss its key factors Describe how the initiation complex controls translation Explain the different ways in which the post-translational control of gene expression takes place After the RNA has been transported to the cytoplasm, it is translated into protein. Control of this process is largely dependent on the RNA molecule. As previously discussed, the stability of the RNA will have a large impact on its translation into a protein. As the stability changes, the amount of time that it is available for translation also changes. The Initiation Complex and Translation Rate Like transcription, translation is controlled by proteins that bind and initiate the process. In translation, the complex that assembles to start the process is referred to as the initiation complex . The first protein to bind to the RNA to initiate translation is the eukaryotic initiation factor-2 (eIF-2) . The eIF-2 protein is active when it binds to the high-energy molecule guanosine triphosphate (GTP) . GTP provides the energy to start the reaction by giving up a phosphate and becoming guanosine diphosphate (GDP) . The eIF-2 protein bound to GTP binds to the small 40S ribosomal subunit . When bound, the methionine initiator tRNA associates with the eIF-2/40S ribosome complex, bringing along with it the mRNA to be translated. At this point, when the initiator complex is assembled, the GTP is converted into GDP and energy is released. The phosphate and the eIF-2 protein are released from the complex and the large 60S ribosomal subunit binds to translate the RNA. The binding of eIF-2 to the RNA is controlled by phosphorylation. If eIF-2 is phosphorylated, it undergoes a conformational change and cannot bind to GTP. Therefore, the initiation complex cannot form properly and translation is impeded ( Figure 16.13 ). When eIF-2 remains unphosphorylated, it binds the RNA and actively translates the protein. Visual Connection An increase in phosphorylation levels of eIF-2 has been observed in patients with neurodegenerative diseases such as Alzheimer’s, Parkinson’s, and Huntington’s. What impact do you think this might have on protein synthesis? Chemical Modifications, Protein Activity, and Longevity Proteins can be chemically modified with the addition of groups including methyl, phosphate, acetyl, and ubiquitin groups. The addition or removal of these groups from proteins regulates their activity or the length of time they exist in the cell. Sometimes these modifications can regulate where a protein is found in the cell—for example, in the nucleus, the cytoplasm, or attached to the plasma membrane. Chemical modifications occur in response to external stimuli such as stress, the lack of nutrients, heat, or ultraviolet light exposure. These changes can alter epigenetic accessibility, transcription, mRNA stability, or translation—all resulting in changes in expression of various genes. This is an efficient way for the cell to rapidly change the levels of specific proteins in response to the environment. Because proteins are involved in every stage of gene regulation, the phosphorylation of a protein (depending on the protein that is modified) can alter accessibility to the chromosome, can alter translation (by altering transcription factor binding or function), can change nuclear shuttling (by influencing modifications to the nuclear pore complex), can alter RNA stability (by binding or not binding to the RNA to regulate its stability), can modify translation (increase or decrease), or can change post-translational modifications (add or remove phosphates or other chemical modifications). The addition of an ubiquitin group to a protein marks that protein for degradation. Ubiquitin acts like a flag indicating that the protein lifespan is complete. These proteins are moved to the proteasome , an organelle that functions to remove proteins, to be degraded ( Figure 16.14 ). One way to control gene expression, therefore, is to alter the longevity of the protein. 16.7 Cancer and Gene Regulation Learning Objectives By the end of this section, you will be able to: Describe how changes to gene expression can cause cancer Explain how changes to gene expression at different levels can disrupt the cell cycle Discuss how understanding regulation of gene expression can lead to better drug design Cancer is not a single disease but includes many different diseases. In cancer cells, mutations modify cell-cycle control and cells don’t stop growing as they normally would. Mutations can also alter the growth rate or the progression of the cell through the cell cycle. One example of a gene modification that alters the growth rate is increased phosphorylation of cyclin B, a protein that controls the progression of a cell through the cell cycle and serves as a cell-cycle checkpoint protein. For cells to move through each phase of the cell cycle, the cell must pass through checkpoints. This ensures that the cell has properly completed the step and has not encountered any mutation that will alter its function. Many proteins, including cyclin B, control these checkpoints. The phosphorylation of cyclin B, a post-translational event, alters its function. As a result, cells can progress through the cell cycle unimpeded, even if mutations exist in the cell and its growth should be terminated. This post-translational change of cyclin B prevents it from controlling the cell cycle and contributes to the development of cancer. Cancer: Disease of Altered Gene Expression Cancer can be described as a disease of altered gene expression. There are many proteins that are turned on or off (gene activation or gene silencing) that dramatically alter the overall activity of the cell. A gene that is not normally expressed in that cell can be switched on and expressed at high levels. This can be the result of gene mutation or changes in gene regulation (epigenetic, transcription, post-transcription, translation, or post-translation). Changes in epigenetic regulation, transcription, RNA stability, protein translation, and post-translational control can be detected in cancer. While these changes don’t occur simultaneously in one cancer, changes at each of these levels can be detected when observing cancer at different sites in different individuals. Therefore, changes in histone acetylation (epigenetic modification that leads to gene silencing), activation of transcription factors by phosphorylation, increased RNA stability, increased translational control, and protein modification can all be detected at some point in various cancer cells. Scientists are working to understand the common changes that give rise to certain types of cancer or how a modification might be exploited to destroy a tumor cell. Tumor Suppressor Genes, Oncogenes, and Cancer In normal cells, some genes function to prevent excess, inappropriate cell growth. These are tumor suppressor genes, which are active in normal cells to prevent uncontrolled cell growth. There are many tumor suppressor genes in cells. The most studied tumor suppressor gene is p53, which is mutated in over 50 percent of all cancer types. The p53 protein itself functions as a transcription factor. It can bind to sites in the promoters of genes to initiate transcription. Therefore, the mutation of p53 in cancer will dramatically alter the transcriptional activity of its target genes. Link to Learning Watch this animation to learn more about the use of p53 in fighting cancer. Proto-oncogenes are positive cell-cycle regulators. When mutated, proto-oncogenes can become oncogenes and cause cancer. Overexpression of the oncogene can lead to uncontrolled cell growth. This is because oncogenes can alter transcriptional activity, stability, or protein translation of another gene that directly or indirectly controls cell growth. An example of an oncogene involved in cancer is a protein called myc. Myc is a transcription factor that is aberrantly activated in Burkett’s Lymphoma, a cancer of the lymph system. Overexpression of myc transforms normal B cells into cancerous cells that continue to grow uncontrollably. High B-cell numbers can result in tumors that can interfere with normal bodily function. Patients with Burkett’s lymphoma can develop tumors on their jaw or in their mouth that interfere with the ability to eat. Cancer and Epigenetic Alterations Silencing genes through epigenetic mechanisms is also very common in cancer cells. There are characteristic modifications to histone proteins and DNA that are associated with silenced genes. In cancer cells, the DNA in the promoter region of silenced genes is methylated on cytosine DNA residues in CpG islands. Histone proteins that surround that region lack the acetylation modification that is present when the genes are expressed in normal cells. This combination of DNA methylation and histone deacetylation (epigenetic modifications that lead to gene silencing) is commonly found in cancer. When these modifications occur, the gene present in that chromosomal region is silenced. Increasingly, scientists understand how epigenetic changes are altered in cancer. Because these changes are temporary and can be reversed—for example, by preventing the action of the histone deacetylase protein that removes acetyl groups, or by DNA methyl transferase enzymes that add methyl groups to cytosines in DNA—it is possible to design new drugs and new therapies to take advantage of the reversible nature of these processes. Indeed, many researchers are testing how a silenced gene can be switched back on in a cancer cell to help re-establish normal growth patterns. Genes involved in the development of many other illnesses, ranging from allergies to inflammation to autism, are thought to be regulated by epigenetic mechanisms. As our knowledge of how genes are controlled deepens, new ways to treat diseases like cancer will emerge. Cancer and Transcriptional Control Alterations in cells that give rise to cancer can affect the transcriptional control of gene expression. Mutations that activate transcription factors, such as increased phosphorylation, can increase the binding of a transcription factor to its binding site in a promoter. This could lead to increased transcriptional activation of that gene that results in modified cell growth. Alternatively, a mutation in the DNA of a promoter or enhancer region can increase the binding ability of a transcription factor. This could also lead to the increased transcription and aberrant gene expression that is seen in cancer cells. Researchers have been investigating how to control the transcriptional activation of gene expression in cancer. Identifying how a transcription factor binds, or a pathway that activates where a gene can be turned off, has led to new drugs and new ways to treat cancer. In breast cancer, for example, many proteins are overexpressed. This can lead to increased phosphorylation of key transcription factors that increase transcription. One such example is the overexpression of the epidermal growth factor receptor (EGFR) in a subset of breast cancers. The EGFR pathway activates many protein kinases that, in turn, activate many transcription factors that control genes involved in cell growth. New drugs that prevent the activation of EGFR have been developed and are used to treat these cancers. Cancer and Post-transcriptional Control Changes in the post-transcriptional control of a gene can also result in cancer. Recently, several groups of researchers have shown that specific cancers have altered expression of miRNAs. Because miRNAs bind to the 3' UTR of RNA molecules to degrade them, overexpression of these miRNAs could be detrimental to normal cellular activity. Too many miRNAs could dramatically decrease the RNA population leading to a decrease in protein expression. Several studies have demonstrated a change in the miRNA population in specific cancer types. It appears that the subset of miRNAs expressed in breast cancer cells is quite different from the subset expressed in lung cancer cells or even from normal breast cells. This suggests that alterations in miRNA activity can contribute to the growth of breast cancer cells. These types of studies also suggest that if some miRNAs are specifically expressed only in cancer cells, they could be potential drug targets. It would, therefore, be conceivable that new drugs that turn off miRNA expression in cancer could be an effective method to treat cancer. Cancer and Translational/Post-translational Control There are many examples of how translational or post-translational modifications of proteins arise in cancer. Modifications are found in cancer cells from the increased translation of a protein to changes in protein phosphorylation to alternative splice variants of a protein. An example of how the expression of an alternative form of a protein can have dramatically different outcomes is seen in colon cancer cells. The c-Flip protein, a protein involved in mediating the cell death pathway, comes in two forms: long (c-FLIPL) and short (c-FLIPS). Both forms appear to be involved in initiating controlled cell death mechanisms in normal cells. However, in colon cancer cells, expression of the long form results in increased cell growth instead of cell death. Clearly, the expression of the wrong protein dramatically alters cell function and contributes to the development of cancer. New Drugs to Combat Cancer: Targeted Therapies Scientists are using what is known about the regulation of gene expression in disease states, including cancer, to develop new ways to treat and prevent disease development. Many scientists are designing drugs on the basis of the gene expression patterns within individual tumors. This idea, that therapy and medicines can be tailored to an individual, has given rise to the field of personalized medicine. With an increased understanding of gene regulation and gene function, medicines can be designed to specifically target diseased cells without harming healthy cells. Some new medicines, called targeted therapies, have exploited the overexpression of a specific protein or the mutation of a gene to develop a new medication to treat disease. One such example is the use of anti-EGF receptor medications to treat the subset of breast cancer tumors that have very high levels of the EGF protein. Undoubtedly, more targeted therapies will be developed as scientists learn more about how gene expression changes can cause cancer. Career Connection Clinical Trial Coordinator A clinical trial coordinator is the person managing the proceedings of the clinical trial. This job includes coordinating patient schedules and appointments, maintaining detailed notes, building the database to track patients (especially for long-term follow-up studies), ensuring proper documentation has been acquired and accepted, and working with the nurses and doctors to facilitate the trial and publication of the results. A clinical trial coordinator may have a science background, like a nursing degree, or other certification. People who have worked in science labs or in clinical offices are also qualified to become a clinical trial coordinator. These jobs are generally in hospitals; however, some clinics and doctor’s offices also conduct clinical trials and may hire a coordinator.
microbiology
Summary 6.1 Viruses Viruses are generally ultramicroscopic, typically from 20 nm to 900 nm in length. Some large viruses have been found. Virions are acellular and consist of a nucleic acid, DNA or RNA, but not both, surrounded by a protein capsid . There may also be a phospholipid membrane surrounding the capsid. Viruses are obligate intracellular parasites. Viruses are known to infect various types of cells found in plants, animals, fungi, protists, bacteria, and archaea. Viruses typically have limited host ranges and infect specific cell types. Viruses may have helical , polyhedral, or complex shapes. Classification of viruses is based on morphology, type of nucleic acid, host range, cell specificity, and enzymes carried within the virion. Like other diseases, viral diseases are classified using ICD codes. 6.2 The Viral Life Cycle Many viruses target specific hosts or tissues. Some may have more than one host. Many viruses follow several stages to infect host cells. These stages include attachment, penetration, uncoating, biosynthesis, maturation, and release . Bacteriophages have a lytic or lysogenic cycle . The lytic cycle leads to the death of the host, whereas the lysogenic cycle leads to integration of phage into the host genome. Bacteriophages inject DNA into the host cell, whereas animal viruses enter by endocytosis or membrane fusion. Animal viruses can undergo latency , similar to lysogeny for a bacteriophage. The majority of plant viruses are positive-strand ssRNA and can undergo latency, chronic, or lytic infection, as observed for animal viruses. The growth curve of bacteriophage populations is a one-step multiplication curve and not a sigmoidal curve, as compared to the bacterial growth curve. Bacteriophages transfer genetic information between hosts using either generalized or specialized transduction . 6.3 Isolation, Culture, and Identification of Viruses Viral cultivation requires the presence of some form of host cell (whole organism, embryo, or cell culture). Viruses can be isolated from samples by filtration. Viral filtrate is a rich source of released virions. Bacteriophages are detected by presence of clear plaques on bacterial lawn. Animal and plant viruses are detected by cytopathic effects , molecular techniques (PCR, RT-PCR), enzyme immunoassays, and serological assays (hemagglutination assay, hemagglutination inhibition assay). 6.4 Viroids, Virusoids, and Prions Other acellular agents such as viroids , virusoids , and prions also cause diseases. Viroids consist of small, naked ssRNAs that cause diseases in plants. Virusoids are ssRNAs that require other helper viruses to establish an infection. Prions are proteinaceous infectious particles that cause transmissible spongiform encephalopathies . Prions are extremely resistant to chemicals, heat, and radiation. There are no treatments for prion infection.
Chapter Outline 6.1 Viruses 6.2 The Viral Life Cycle 6.3 Isolation, Culture, and Identification of Viruses 6.4 Viroids, Virusoids, and Prions Introduction Public health measures in the developed world have dramatically reduced mortality from viral epidemics. But when epidemics do occur, they can spread quickly with global air travel. In 2009, an outbreak of H1N1 influenza spread across various continents. In early 2014, cases of Ebola in Guinea led to a massive epidemic in western Africa. This included the case of an infected man who traveled to the United States, sparking fears the epidemic might spread beyond Africa. Until the late 1930s and the advent of the electron microscope, no one had seen a virus. Yet treatments for preventing or curing viral infections were used and developed long before that. Historical records suggest that by the 17th century, and perhaps earlier, inoculation (also known as variolation) was being used to prevent the viral disease smallpox in various parts of the world. By the late 18th century, Englishman Edward Jenner was inoculating patients with cowpox to prevent smallpox, a technique he coined vaccination . 1 1 S. Riedel “Edward Jenner and the History of Smallpox and Vaccination.” Baylor University Medical Center Proceedings 18, no. 1 (January 2005): 21–25. Today, the structure and genetics of viruses are well defined, yet new discoveries continue to reveal their complexities. In this chapter, we will learn about the structure, classification, and cultivation of viruses, and how they impact their hosts. In addition, we will learn about other infective particles such as viroids and prions.
[ { "answer": { "ans_choice": 1, "ans_text": "B" }, "bloom": null, "hl_context": "Extending outward and away from the capsid on some naked viruses and enveloped viruses are protein structures called spike s . <hl> At the tips of these spikes are structures that allow the virus to attach and enter a cell , like the influenza virus hemagglutinin spikes ( H ) or enzymes like the neuraminidase ( N ) influenza virus spikes that allow the virus to detach from the cell surface during release of new virions . <hl> Influenza viruses are often identified by their H and N spikes . For example , H1N1 influenza viruses were responsible for the pandemics in 1918 and 2009 , 8 H2N2 for the pandemic in 1957 , and H3N2 for the pandemic in 1968 . 8 J . Cohen . “ What ’ s Old Is New : 1918 Virus Matches 2009 H1N1 Strain . Science 327 , no . 5973 ( 2010 ): 1563 – 1564 .", "hl_sentences": "At the tips of these spikes are structures that allow the virus to attach and enter a cell , like the influenza virus hemagglutinin spikes ( H ) or enzymes like the neuraminidase ( N ) influenza virus spikes that allow the virus to detach from the cell surface during release of new virions .", "question": { "cloze_format": "The component(s) of a virus that is/are extended from the envelope for attachment is/are the ___ .", "normal_format": "What is/are the component(s) of a virus that is/are extended from the envelope for attachment?", "question_choices": [ "capsomeres", "spikes", "nucleic acid", "viral whiskers" ], "question_id": "fs-id1168325632138", "question_text": "The component(s) of a virus that is/are extended from the envelope for attachment is/are the:" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 1, "ans_text": "B" }, "bloom": null, "hl_context": "There are two categories of viruses based on general composition . Viruses formed from only a nucleic acid and capsid are called naked virus es or nonenveloped virus es . Viruses formed with a nucleic-acid packed capsid surrounded by a lipid layer are called enveloped virus es ( see Figure 6.5 ) . <hl> The viral envelope is a small portion of phospholipid membrane obtained as the virion buds from a host cell . <hl> <hl> The viral envelope may either be intracellular or cytoplasmic in origin . <hl>", "hl_sentences": "The viral envelope is a small portion of phospholipid membrane obtained as the virion buds from a host cell . The viral envelope may either be intracellular or cytoplasmic in origin .", "question": { "cloze_format": "The envelope of a virus is derived from the host’s ___.", "normal_format": "The envelope of a virus is derived from which host’s part?", "question_choices": [ "nucleic acids", "membrane structures", "cytoplasm", "genome" ], "question_id": "fs-id1168327871169", "question_text": "The envelope of a virus is derived from the host’s" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 1, "ans_text": "B" }, "bloom": null, "hl_context": "Although viruses are not classified in the three domains of life , their numbers are great enough to require classification . Since 1971 , the International Union of Microbiological Societies Virology Division has given the task of developing , refining , and maintaining a universal virus taxonomy to the International Committee on Taxonomy of Viruses ( ICTV ) . Since viruses can mutate so quickly , it can be difficult to classify them into a genus and a species epithet using the binomial nomenclature system . Thus , the ICTV ’ s viral nomenclature system classifies viruses into families and genera based on viral genetics , chemistry , morphology , and mechanism of multiplication . <hl> To date , the ICTV has classified known viruses in seven orders , 96 families , and 350 genera . <hl> <hl> Viral family names end in - viridae ( e . g , Parvoviridae ) and genus names end in − virus ( e . g . , Parvovirus ) . <hl> <hl> The names of viral orders , families , and genera are all italicized . <hl> When referring to a viral species , we often use a genus and species epithet such as Pandoravirus dulcis or Pandoravirus salinus .", "hl_sentences": "To date , the ICTV has classified known viruses in seven orders , 96 families , and 350 genera . Viral family names end in - viridae ( e . g , Parvoviridae ) and genus names end in − virus ( e . g . , Parvovirus ) . The names of viral orders , families , and genera are all italicized .", "question": { "cloze_format": "In naming viruses, the family name ends with ________ and genus name ends with _________.", "normal_format": "In naming viruses, How the family name and genus name respectively end with?", "question_choices": [ "−virus; −viridae", "−viridae; −virus", "−virion; virus", "−virus; virion" ], "question_id": "fs-id1168327927708", "question_text": "In naming viruses, the family name ends with ________ and genus name ends with _________." }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 2, "ans_text": "C" }, "bloom": null, "hl_context": "There are two categories of viruses based on general composition . <hl> Viruses formed from only a nucleic acid and capsid are called naked virus es or nonenveloped virus es . <hl> Viruses formed with a nucleic-acid packed capsid surrounded by a lipid layer are called enveloped virus es ( see Figure 6.5 ) . The viral envelope is a small portion of phospholipid membrane obtained as the virion buds from a host cell . The viral envelope may either be intracellular or cytoplasmic in origin .", "hl_sentences": "Viruses formed from only a nucleic acid and capsid are called naked virus es or nonenveloped virus es .", "question": { "cloze_format": "Another name for a nonenveloped virus is a/an ___.", "normal_format": "What is another name for a nonenveloped virus?", "question_choices": [ "enveloped virus", "provirus", "naked virus", "latent virus" ], "question_id": "fs-id1168328214168", "question_text": "What is another name for a nonenveloped virus?" }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 1, "ans_text": "B" }, "bloom": null, "hl_context": "Transduction occurs when a bacteriophage transfers bacterial DNA from one bacterium to another during sequential infections . There are two types of transduction : generalized and specialized transduction . <hl> During the lytic cycle of viral replication , the virus hijacks the host cell , degrades the host chromosome , and makes more viral genomes . <hl> As it assembles and packages DNA into the phage head , packaging occasionally makes a mistake . Instead of packaging viral DNA , it takes a random piece of host DNA and inserts it into the capsid . Once released , this virion will then inject the former host ’ s DNA into a newly infected host . The asexual transfer of genetic information can allow for DNA recombination to occur , thus providing the new host with new genes ( e . g . , an antibiotic-resistance gene , or a sugar-metabolizing gene ) . Generalized transduction occurs when a random piece of bacterial chromosomal DNA is transferred by the phage during the lytic cycle . Specialized transduction occurs at the end of the lysogenic cycle , when the prophage is excised and the bacteriophage enters the lytic cycle . Since the phage is integrated into the host genome , the prophage can replicate as part of the host . However , some conditions ( e . g . , ultraviolet light exposure or chemical exposure ) stimulate the prophage to undergo induction , causing the phage to excise from the genome , enter the lytic cycle , and produce new phages to leave host cells . During the process of excision from the host chromosome , a phage may occasionally remove some bacterial DNA near the site of viral integration . The phage and host DNA from one end or both ends of the integration site are packaged within the capsid and are transferred to the new , infected host . Since the DNA transferred by the phage is not randomly packaged but is instead a specific piece of DNA near the site of integration , this mechanism of gene transfer is referred to as specialized transduction ( see Figure 6.9 ) . The DNA can then recombine with host chromosome , giving the latter new characteristics . Transduction seems to play an important role in the evolutionary process of bacteria , giving them a mechanism for asexual exchange of genetic information .", "hl_sentences": "During the lytic cycle of viral replication , the virus hijacks the host cell , degrades the host chromosome , and makes more viral genomes .", "question": { "cloze_format": "The ___ leads to the destruction of the host cells.", "normal_format": "Which of the following leads to the destruction of the host cells?", "question_choices": [ "lysogenic cycle", "lytic cycle", "prophage", "temperate phage" ], "question_id": "fs-id1168329265123", "question_text": "Which of the following leads to the destruction of the host cells?" }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 3, "ans_text": "D" }, "bloom": null, "hl_context": "<hl> Extending outward and away from the capsid on some naked viruses and enveloped viruses are protein structures called spike s . <hl> <hl> At the tips of these spikes are structures that allow the virus to attach and enter a cell , like the influenza virus hemagglutinin spikes ( H ) or enzymes like the neuraminidase ( N ) influenza virus spikes that allow the virus to detach from the cell surface during release of new virions . <hl> Influenza viruses are often identified by their H and N spikes . For example , H1N1 influenza viruses were responsible for the pandemics in 1918 and 2009 , 8 H2N2 for the pandemic in 1957 , and H3N2 for the pandemic in 1968 . 8 J . Cohen . “ What ’ s Old Is New : 1918 Virus Matches 2009 H1N1 Strain . Science 327 , no . 5973 ( 2010 ): 1563 – 1564 .", "hl_sentences": "Extending outward and away from the capsid on some naked viruses and enveloped viruses are protein structures called spike s . At the tips of these spikes are structures that allow the virus to attach and enter a cell , like the influenza virus hemagglutinin spikes ( H ) or enzymes like the neuraminidase ( N ) influenza virus spikes that allow the virus to detach from the cell surface during release of new virions .", "question": { "cloze_format": "A virus obtains its envelope during the ___ phase.", "normal_format": "A virus obtains its envelope during which of the following phases?", "question_choices": [ "attachment", "penetration", "assembly", "release" ], "question_id": "fs-id1168329265156", "question_text": "A virus obtains its envelope during which of the following phases?" }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 3, "ans_text": "D" }, "bloom": null, "hl_context": "An alternative mechanism for viral nucleic acid synthesis is observed in the retrovirus es , which are + ssRNA viruses ( see Figure 6.12 ) . <hl> Single-stranded RNA viruses such as HIV carry a special enzyme called reverse transcriptase within the capsid that synthesizes a complementary ssDNA ( cDNA ) copy using the + ssRNA genome as a template . <hl> The ssDNA is then made into dsDNA , which can integrate into the host chromosome and become a permanent part of the host . The integrated viral genome is called a provirus . The virus now can remain in the host for a long time to establish a chronic infection . The provirus stage is similar to the prophage stage in a bacterial infection during the lysogenic cycle . However , unlike prophage , the provirus does not undergo excision after splicing into the genome .", "hl_sentences": "Single-stranded RNA viruses such as HIV carry a special enzyme called reverse transcriptase within the capsid that synthesizes a complementary ssDNA ( cDNA ) copy using the + ssRNA genome as a template .", "question": { "cloze_format": "The component that is brought into a cell by HIV is ___ .", "normal_format": "Which of the following components is brought into a cell by HIV?", "question_choices": [ "a DNA-dependent DNA polymerase", "RNA polymerase", "ribosome", "reverse transcriptase" ], "question_id": "fs-id1168329002208", "question_text": "Which of the following components is brought into a cell by HIV?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 1, "ans_text": "B" }, "bloom": null, "hl_context": "<hl> If the viral genome is RNA , a different mechanism must be used . <hl> There are three types of RNA genome : dsRNA , positive ( + ) single-strand ( + ssRNA ) or negative ( − ) single-strand RNA ( − ssRNA ) . <hl> If a virus has a + ssRNA genome , it can be translated directly to make viral proteins . <hl> Viral genomic + ssRNA acts like cellular mRNA . However , if a virus contains a − ssRNA genome , the host ribosomes cannot translate it until the − ssRNA is replicated into + ssRNA by viral RNA-dependent RNA polymerase ( RdRP ) ( see Figure 6.11 ) . The RdRP is brought in by the virus and can be used to make + ssRNA from the original − ssRNA genome . The RdRP is also an important enzyme for the replication of dsRNA viruses , because it uses the negative strand of the double-stranded genome as a template to create + ssRNA . The newly synthesized + ssRNA copies can then be translated by cellular ribosomes .", "hl_sentences": "If the viral genome is RNA , a different mechanism must be used . If a virus has a + ssRNA genome , it can be translated directly to make viral proteins .", "question": { "cloze_format": "A positive-strand RNA virus ___ .", "normal_format": "What is a characteristic of a positive-strand RNA virus?", "question_choices": [ "must first be converted to a mRNA before it can be translated.", "can be used directly to translate viral proteins.", "will be degraded by host enzymes.", "is not recognized by host ribosomes." ], "question_id": "fs-id1168329038074", "question_text": "A positive-strand RNA virus:" }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 0, "ans_text": "A" }, "bloom": null, "hl_context": "<hl> Transduction occurs when a bacteriophage transfers bacterial DNA from one bacterium to another during sequential infections . <hl> There are two types of transduction : generalized and specialized transduction . During the lytic cycle of viral replication , the virus hijacks the host cell , degrades the host chromosome , and makes more viral genomes . As it assembles and packages DNA into the phage head , packaging occasionally makes a mistake . Instead of packaging viral DNA , it takes a random piece of host DNA and inserts it into the capsid . Once released , this virion will then inject the former host ’ s DNA into a newly infected host . The asexual transfer of genetic information can allow for DNA recombination to occur , thus providing the new host with new genes ( e . g . , an antibiotic-resistance gene , or a sugar-metabolizing gene ) . Generalized transduction occurs when a random piece of bacterial chromosomal DNA is transferred by the phage during the lytic cycle . Specialized transduction occurs at the end of the lysogenic cycle , when the prophage is excised and the bacteriophage enters the lytic cycle . Since the phage is integrated into the host genome , the prophage can replicate as part of the host . However , some conditions ( e . g . , ultraviolet light exposure or chemical exposure ) stimulate the prophage to undergo induction , causing the phage to excise from the genome , enter the lytic cycle , and produce new phages to leave host cells . During the process of excision from the host chromosome , a phage may occasionally remove some bacterial DNA near the site of viral integration . The phage and host DNA from one end or both ends of the integration site are packaged within the capsid and are transferred to the new , infected host . Since the DNA transferred by the phage is not randomly packaged but is instead a specific piece of DNA near the site of integration , this mechanism of gene transfer is referred to as specialized transduction ( see Figure 6.9 ) . The DNA can then recombine with host chromosome , giving the latter new characteristics . Transduction seems to play an important role in the evolutionary process of bacteria , giving them a mechanism for asexual exchange of genetic information .", "hl_sentences": "Transduction occurs when a bacteriophage transfers bacterial DNA from one bacterium to another during sequential infections .", "question": { "cloze_format": "___ is the name for the transfer of genetic information from one bacterium to another bacterium by a phage.", "normal_format": "What is the name for the transfer of genetic information from one bacterium to another bacterium by a phage?", "question_choices": [ "transduction", "penetration", "excision", "translation" ], "question_id": "fs-id1168329066690", "question_text": "What is the name for the transfer of genetic information from one bacterium to another bacterium by a phage?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 1, "ans_text": "B" }, "bloom": null, "hl_context": "<hl> The embryo or host animal serves as an incubator for viral replication ( see Figure 6.18 ) . <hl> Location within the embryo or host animal is important . Many viruses have a tissue tropism , and must therefore be introduced into a specific site for growth . Within an embryo , target sites include the amniotic cavity , the chorioallantoic membrane , or the yolk sac . Viral infection may damage tissue membranes , producing lesions called pox ; disrupt embryonic development ; or cause the death of the embryo . <hl> Animal viruses require cells within a host animal or tissue-culture cells derived from an animal . <hl> Animal virus cultivation is important for 1 ) identification and diagnosis of pathogenic viruses in clinical specimens , 2 ) production of vaccines , and 3 ) basic research studies . In vivo host sources can be a developing embryo in an embryonated bird ’ s egg ( e . g . , chicken , turkey ) or a whole animal . For example , most of the influenza vaccine manufactured for annual flu vaccination programs is cultured in hens ’ eggs . <hl> Viruses can be grown in vivo ( within a whole living organism , plant , or animal ) or in vitro ( outside a living organism in cells in an artificial environment . <hl> Flat horizontal cell culture flasks ( see Figure 6.17 ( a ) ) are a common vessel used for in vitro work . Bacteriophages can be grown in the presence of a dense layer of bacteria ( also called a bacterial lawn ) grown in a 0.7 % soft agar in a Petri dish or flat ( horizontal ) flask ( see Figure 6.17 ( b ) ) . As the phage kills the bacteria , many plaques are observed among the cloudy bacterial lawn .", "hl_sentences": "The embryo or host animal serves as an incubator for viral replication ( see Figure 6.18 ) . Animal viruses require cells within a host animal or tissue-culture cells derived from an animal . Viruses can be grown in vivo ( within a whole living organism , plant , or animal ) or in vitro ( outside a living organism in cells in an artificial environment .", "question": { "cloze_format": "The ___ cannot be used to culture viruses.", "normal_format": "Which of the followings cannot be used to culture viruses?", "question_choices": [ "tissue culture", "liquid medium only", "embryo", "animal host" ], "question_id": "fs-id1168327925720", "question_text": "Which of the followings cannot be used to culture viruses?" }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 3, "ans_text": "D" }, "bloom": null, "hl_context": "<hl> Enzyme immunoassays ( EIAs ) rely on the ability of antibodies to detect and attach to specific biomolecules called antigens . <hl> <hl> The detecting antibody attaches to the target antigen with a high degree of specificity in what might be a complex mixture of biomolecules . <hl> Also included in this type of assay is a colorless enzyme attached to the detecting antibody . The enzyme acts as a tag on the detecting antibody and can interact with a colorless substrate , leading to the production of a colored end product . EIAs often rely on layers of antibodies to capture and react with antigens , all of which are attached to a membrane filter ( see Figure 6.23 ) . <hl> EIAs for viral antigens are often used as preliminary screening tests . <hl> If the results are positive , further confirmation will require tests with even greater sensitivity , such as a western blot or an NAAT . EIAs are discussed in more detail in EIAs and ELISAs . <hl> Reverse transcriptase-PCR ( RT-PCR ) is an NAAT used to detect the presence of RNA viruses . <hl> RT-PCR differs from PCR in that the enzyme reverse transcriptase ( RT ) is used to make a cDNA from the small amount of viral RNA in the specimen . The cDNA can then be amplified by PCR . <hl> Both PCR and RT-PCR are used to detect and confirm the presence of the viral nucleic acid in patient specimens . <hl> <hl> Nucleic acid amplification tests ( NAAT ) are used in molecular biology to detect unique nucleic acid sequences of viruses in patient samples . <hl> <hl> Polymerase chain reaction ( PCR ) is an NAAT used to detect the presence of viral DNA in a patient ’ s tissue or body fluid sample . <hl> PCR is a technique that amplifies ( i . e . , synthesizes many copies ) of a viral DNA segment of interest . Using PCR , short nucleotide sequences called primers bind to specific sequences of viral DNA , enabling identification of the virus .", "hl_sentences": "Enzyme immunoassays ( EIAs ) rely on the ability of antibodies to detect and attach to specific biomolecules called antigens . The detecting antibody attaches to the target antigen with a high degree of specificity in what might be a complex mixture of biomolecules . EIAs for viral antigens are often used as preliminary screening tests . Reverse transcriptase-PCR ( RT-PCR ) is an NAAT used to detect the presence of RNA viruses . Both PCR and RT-PCR are used to detect and confirm the presence of the viral nucleic acid in patient specimens . Nucleic acid amplification tests ( NAAT ) are used in molecular biology to detect unique nucleic acid sequences of viruses in patient samples . Polymerase chain reaction ( PCR ) is an NAAT used to detect the presence of viral DNA in a patient ’ s tissue or body fluid sample .", "question": { "cloze_format": "The test that can be used to detect the presence of a specific virus is the ___.", "normal_format": "Which of the following tests can be used to detect the presence of a specific virus?", "question_choices": [ "EIA", "RT-PCR", "PCR", "all of the above" ], "question_id": "fs-id1168327875814", "question_text": "Which of the following tests can be used to detect the presence of a specific virus?" }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 2, "ans_text": "C" }, "bloom": null, "hl_context": "Regardless of the method of cultivation , once a virus has been introduced into a whole host organism , embryo , or tissue-culture cell , a sample can be prepared from the infected host , embryo , or cell line for further analysis under a brightfield , electron , or fluorescent microscope . Cytopathic effects ( CPEs ) are distinct observable cell abnormalities due to viral infection . <hl> CPEs can include loss of adherence to the surface of the container , changes in cell shape from flat to round , shrinkage of the nucleus , vacuoles in the cytoplasm , fusion of cytoplasmic membranes and the formation of multinucleated syncytia , inclusion bodies in the nucleus or cytoplasm , and complete cell lysis ( see Figure 6.21 ) . <hl>", "hl_sentences": "CPEs can include loss of adherence to the surface of the container , changes in cell shape from flat to round , shrinkage of the nucleus , vacuoles in the cytoplasm , fusion of cytoplasmic membranes and the formation of multinucleated syncytia , inclusion bodies in the nucleus or cytoplasm , and complete cell lysis ( see Figure 6.21 ) .", "question": { "cloze_format": "___ is/are NOT a cytopathic effect.", "normal_format": "Which of the following is NOT a cytopathic effect?", "question_choices": [ "transformation", "cell fusion", "mononucleated cell", "inclusion bodies" ], "question_id": "fs-id1168328248091", "question_text": "Which of the following is NOT a cytopathic effect?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 3, "ans_text": "D" }, "bloom": null, "hl_context": "<hl> Research attempts to discover the causative agents of previously uninvestigated diseases have led to the discovery of nonliving disease agents quite different from viruses . <hl> <hl> These include particles consisting only of RNA or only of protein that , nonetheless , are able to self-propagate at the expense of a host — a key similarity to viruses that allows them to cause disease conditions . <hl> <hl> To date , these discoveries include viroids , virusoids , and the proteinaceous prions . <hl>", "hl_sentences": "Research attempts to discover the causative agents of previously uninvestigated diseases have led to the discovery of nonliving disease agents quite different from viruses . These include particles consisting only of RNA or only of protein that , nonetheless , are able to self-propagate at the expense of a host — a key similarity to viruses that allows them to cause disease conditions . To date , these discoveries include viroids , virusoids , and the proteinaceous prions .", "question": { "cloze_format": "The infectious agents that do not have nucleic acid are ___.", "normal_format": "Which of these infectious agents do not have nucleic acid?", "question_choices": [ "viroids", "viruses", "bacteria", "prions" ], "question_id": "fs-id1168327894164", "question_text": "Which of these infectious agents do not have nucleic acid?" }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 2, "ans_text": "C" }, "bloom": null, "hl_context": "<hl> A prion is a misfolded rogue form of a normal protein ( PrPc ) found in the cell . <hl> This rogue prion protein ( PrPsc ) , which may be caused by a genetic mutation or occur spontaneously , can be infectious , stimulating other endogenous normal proteins to become misfolded , forming plaques ( see Figure 6.25 ) . Today , prions are known to cause various forms of transmissible spongiform encephalopathy ( TSE ) in human and animals . TSE is a rare degenerative disorder that affects the brain and nervous system . The accumulation of rogue proteins causes the brain tissue to become sponge-like , killing brain cells and forming holes in the tissue , leading to brain damage , loss of motor coordination , and dementia ( see Figure 6.26 ) . Infected individuals are mentally impaired and become unable to move or speak . There is no cure , and the disease progresses rapidly , eventually leading to death within a few months or years .", "hl_sentences": "A prion is a misfolded rogue form of a normal protein ( PrPc ) found in the cell .", "question": { "cloze_format": "A true statement of prions is that ___ .", "normal_format": "Which of the following is true of prions?", "question_choices": [ "They can be inactivated by boiling at 100 °C.", "They contain a capsid.", "They are a rogue form of protein, PrP.", "They can be reliably inactivated by an autoclave." ], "question_id": "fs-id1168327940737", "question_text": "Which of the following is true of prions?" }, "references_are_paraphrase": null } ]
6
6.1 Viruses Learning Objectives Describe the general characteristics of viruses as pathogens Describe viral genomes Describe the general characteristics of viral life cycles Differentiate among bacteriophages, plant viruses, and animal viruses Describe the characteristics used to identify viruses as obligate intracellular parasites Clinical Focus Part 1 David, a 45-year-old journalist, has just returned to the U.S. from travels in Russia, China, and Africa. He is not feeling well, so he goes to his general practitioner complaining of weakness in his arms and legs, fever, headache, noticeable agitation, and minor discomfort. He thinks it may be related to a dog bite he suffered while interviewing a Chinese farmer. He is experiencing some prickling and itching sensations at the site of the bite wound, but he tells the doctor that the dog seemed healthy and that he had not been concerned until now. The doctor ordered a culture and sensitivity test to rule out bacterial infection of the wound, and the results came back negative for any possible pathogenic bacteria. Based on this information, what additional tests should be performed on the patient? What type of treatment should the doctor recommend? Jump to the next Clinical Focus box. Despite their small size, which prevented them from being seen with light microscopes, the discovery of a filterable component smaller than a bacterium that causes tobacco mosaic disease (TMD) dates back to 1892. 2 At that time, Dmitri Ivanovski , a Russian botanist, discovered the source of TMD by using a porcelain filtering device first invented by Charles Chamberland and Louis Pasteur in Paris in 1884. Porcelain Chamberland filters have a pore size of 0.1 µm, which is small enough to remove all bacteria ≥0.2 µm from any liquids passed through the device. An extract obtained from TMD-infected tobacco plants was made to determine the cause of the disease. Initially, the source of the disease was thought to be bacterial. It was surprising to everyone when Ivanovski, using a Chamberland filter, found that the cause of TMD was not removed after passing the extract through the porcelain filter. So if a bacterium was not the cause of TMD, what could be causing the disease? Ivanovski concluded the cause of TMD must be an extremely small bacterium or bacterial spore. Other scientists, including Martinus Beijerinck , continued investigating the cause of TMD. It was Beijerinck, in 1899, who eventually concluded the causative agent was not a bacterium but, instead, possibly a chemical, like a biological poison we would describe today as a toxin. As a result, the word virus , Latin for poison, was used to describe the cause of TMD a few years after Ivanovski’s initial discovery. Even though he was not able to see the virus that caused TMD, and did not realize the cause was not a bacterium, Ivanovski is credited as the original discoverer of viruses and a founder of the field of virology. 2 H. Lecoq. “[Discovery of the First Virus, the Tobacco Mosaic Virus: 1892 or 1898?].” Comptes Rendus de l’Academie des Sciences – Serie III – Sciences de la Vie 324, no. 10 (2001): 929–933. Today, we can see viruses using electron microscopes ( Figure 6.2 ) and we know much more about them. Viruses are distinct biological entities; however, their evolutionary origin is still a matter of speculation. In terms of taxonomy, they are not included in the tree of life because they are acellular (not consisting of cells). In order to survive and reproduce, viruses must infect a cellular host, making them obligate intracellular parasites. The genome of a virus enters a host cell and directs the production of the viral components, proteins and nucleic acids, needed to form new virus particles called virion s . New virions are made in the host cell by assembly of viral components. The new virions transport the viral genome to another host cell to carry out another round of infection. Table 6.1 summarizes the properties of viruses. Characteristics of Viruses Infectious, acellular pathogens Obligate intracellular parasites with host and cell-type specificity DNA or RNA genome (never both) Genome is surrounded by a protein capsid and, in some cases, a phospholipid membrane studded with viral glycoproteins Lack genes for many products needed for successful reproduction, requiring exploitation of host-cell genomes to reproduce Table 6.1 Check Your Understanding Why was the first virus investigated mistaken for a toxin? Hosts and Viral Transmission Viruses can infect every type of host cell, including those of plants, animals, fungi, protists, bacteria, and archaea. Most viruses will only be able to infect the cells of one or a few species of organism. This is called the host range . However, having a wide host range is not common and viruses will typically only infect specific hosts and only specific cell types within those hosts. The viruses that infect bacteria are called bacteriophage s , or simply phages. The word phage comes from the Greek word for devour. Other viruses are just identified by their host group, such as animal or plant viruses. Once a cell is infected, the effects of the virus can vary depending on the type of virus. Viruses may cause abnormal growth of the cell or cell death, alter the cell’s genome, or cause little noticeable effect in the cell. Viruses can be transmitted through direct contact, indirect contact with fomites , or through a vector : an animal that transmits a pathogen from one host to another. Arthropods such as mosquitoes, ticks, and flies, are typical vectors for viral diseases, and they may act as mechanical vector s or biological vector s . Mechanical transmission occurs when the arthropod carries a viral pathogen on the outside of its body and transmits it to a new host by physical contact. Biological transmission occurs when the arthropod carries the viral pathogen inside its body and transmits it to the new host through biting. In humans, a wide variety of viruses are capable of causing various infections and diseases. Some of the deadliest emerging pathogens in humans are viruses, yet we have few treatments or drugs to deal with viral infections, making them difficult to eradicate. Viruses that can be transmitted from an animal host to a human host can cause zoonoses . For example, the avian influenza virus originates in birds, but can cause disease in humans. Reverse zoonoses are caused by infection of an animal by a virus that originated in a human. Micro Connections Fighting Bacteria with Viruses The emergence of superbugs, or multidrug resistant bacteria , has become a major challenge for pharmaceutical companies and a serious health-care problem. According to a 2013 report by the US Centers for Disease Control and Prevention (CDC), more than 2 million people are infected with drug-resistant bacteria in the US annually, resulting in at least 23,000 deaths. 3 The continued use and overuse of antibiotics will likely lead to the evolution of even more drug-resistant strains. 3 US Department of Health and Human Services, Centers for Disease Control and Prevention. “Antibiotic Resistance Threats in the United States, 2013.” http://www.cdc.gov/drugresistance/pdf/ar-threats-2013-508.pdf (accessed September 22, 2015). One potential solution is the use of phage therapy , a procedure that uses bacteria-killing viruses (bacteriophages) to treat bacterial infections. Phage therapy is not a new idea. The discovery of bacteriophages dates back to the early 20th century, and phage therapy was first used in Europe in 1915 by the English bacteriologist Frederick Twort . 4 However, the subsequent discovery of penicillin and other antibiotics led to the near abandonment of this form of therapy, except in the former Soviet Union and a few countries in Eastern Europe. Interest in phage therapy outside of the countries of the former Soviet Union is only recently re-emerging because of the rise in antibiotic-resistant bacteria. 5 4 M. Clokie et al. “Phages in Nature.” Bacteriophage 1, no. 1 (2011): 31–45. 5 A. Sulakvelidze et al. “Bacteriophage Therapy.” Antimicrobial Agents and Chemotherapy 45, no. 3 (2001): 649–659. Phage therapy has some advantages over antibiotics in that phages kill only one specific bacterium, whereas antibiotics kill not only the pathogen but also beneficial bacteria of the normal microbiota. Development of new antibiotics is also expensive for drug companies and for patients, especially for those who live in countries with high poverty rates. Phages have also been used to prevent food spoilage. In 2006, the US Food and Drug Administration approved the use of a solution containing six bacteriophages that can be sprayed on lunch meats such as bologna, ham, and turkey to kill Listeria monocytogenes , a bacterium responsible for listeriosis, a form of food poisoning. Some consumers have concerns about the use of phages on foods, however, especially given the rising popularity of organic products. Foods that have been treated with phages must declare “ bacteriophage preparation ” in the list of ingredients or include a label declaring that the meat has been “treated with antimicrobial solution to reduce microorganisms.” 6 6 US Food and Drug Administration. “FDA Approval of Listeria -specific Bacteriophage Preparation on Ready-to-Eat (RTE) Meat and Poultry Products.” http://www.fda.gov/food/ingredientspackaginglabeling/ucm083572.htm (accessed September 22, 2015). Check Your Understanding Why do humans not have to be concerned about the presence of bacteriophages in their food? What are three ways that viruses can be transmitted between hosts? Viral Structures In general, virions (viral particles) are small and cannot be observed using a regular light microscope. They are much smaller than prokaryotic and eukaryotic cells; this is an adaptation allowing viruses to infect these larger cells (see Figure 6.3 ). The size of a virion can range from 20 nm for small viruses up to 900 nm for typical, large viruses (see Figure 6.4 ). Recent discoveries, however, have identified new giant viral species , such as Pandoravirus salinus and Pithovirus sibericum , with sizes approaching that of a bacterial cell. 7 7 N. Philippe et al. “Pandoraviruses: Amoeba Viruses with Genomes up to 2.5 Mb Reaching that of Parasitic Eukaryotes.” Science 341, no. 6143 (2013): 281–286. In 1935, after the development of the electron microscope, Wendell Stanley was the first scientist to crystallize the structure of the tobacco mosaic virus and discovered that it is composed of RNA and protein. In 1943, he isolated Influenza B virus , which contributed to the development of an influenza (flu) vaccine. Stanley’s discoveries unlocked the mystery of the nature of viruses that had been puzzling scientists for over 40 years and his contributions to the field of virology led to him being awarded the Nobel Prize in 1946. As a result of continuing research into the nature of viruses, we now know they consist of a nucleic acid (either RNA or DNA, but never both) surrounded by a protein coat called a capsid (see Figure 6.5 ). The interior of the capsid is not filled with cytosol, as in a cell, but instead it contains the bare necessities in terms of genome and enzymes needed to direct the synthesis of new virions. Each capsid is composed of protein subunits called capsomere s made of one or more different types of capsomere proteins that interlock to form the closely packed capsid. There are two categories of viruses based on general composition. Viruses formed from only a nucleic acid and capsid are called naked virus es or nonenveloped virus es . Viruses formed with a nucleic-acid packed capsid surrounded by a lipid layer are called enveloped virus es (see Figure 6.5 ). The viral envelope is a small portion of phospholipid membrane obtained as the virion buds from a host cell. The viral envelope may either be intracellular or cytoplasmic in origin. Extending outward and away from the capsid on some naked viruses and enveloped viruses are protein structures called spike s . At the tips of these spikes are structures that allow the virus to attach and enter a cell, like the influenza virus hemagglutinin spikes (H) or enzymes like the neuraminidase (N) influenza virus spikes that allow the virus to detach from the cell surface during release of new virions. Influenza viruses are often identified by their H and N spikes. For example, H1N1 influenza viruses were responsible for the pandemics in 1918 and 2009, 8 H2N2 for the pandemic in 1957, and H3N2 for the pandemic in 1968. 8 J. Cohen. “What’s Old Is New: 1918 Virus Matches 2009 H1N1 Strain. Science 327, no. 5973 (2010): 1563–1564. Viruses vary in the shape of their capsids, which can be either helical , polyhedral , or complex . A helical capsid forms the shape of tobacco mosaic virus (TMV), a naked helical virus , and Ebola virus, an enveloped helical virus. The capsid is cylindrical or rod shaped, with the genome fitting just inside the length of the capsid. Polyhedral capsids form the shapes of poliovirus and rhinovirus, and consist of a nucleic acid surrounded by a polyhedral (many-sided) capsid in the form of an icosahedron. An icosahedral capsid is a three-dimensional, 20-sided structure with 12 vertices. These capsids somewhat resemble a soccer ball. Both helical and polyhedral viruses can have envelopes. Viral shapes seen in certain types of bacteriophages, such as T4 phage, and poxviruses, like vaccinia virus, may have features of both polyhedral and helical viruses so they are described as a complex viral shape (see Figure 6.6 ). In the bacteriophage complex form, the genome is located within the polyhedral head and the sheath connects the head to the tail fiber s and tail pins that help the virus attach to receptors on the host cell’s surface. Poxviruses that have complex shapes are often brick shaped, with intricate surface characteristics not seen in the other categories of capsid. Check Your Understanding Which types of viruses have spikes? Classification and Taxonomy of Viruses Although viruses are not classified in the three domains of life, their numbers are great enough to require classification. Since 1971, the International Union of Microbiological Societies Virology Division has given the task of developing, refining, and maintaining a universal virus taxonomy to the International Committee on Taxonomy of Viruses (ICTV) . Since viruses can mutate so quickly, it can be difficult to classify them into a genus and a species epithet using the binomial nomenclature system. Thus, the ICTV’s viral nomenclature system classifies viruses into families and genera based on viral genetics, chemistry, morphology, and mechanism of multiplication. To date, the ICTV has classified known viruses in seven orders, 96 families, and 350 genera. Viral family names end in - viridae (e.g, Parvoviridae ) and genus names end in −virus (e.g., Parvovirus ). The names of viral orders, families, and genera are all italicized. When referring to a viral species, we often use a genus and species epithet such as Pandoravirus dulcis or Pandoravirus salinus. The Baltimore classification system is an alternative to ICTV nomenclature. The Baltimore system classifies viruses according to their genomes (DNA or RNA, single versus double stranded, and mode of replication). This system thus creates seven groups of viruses that have common genetics and biology. Link to Learning Explore the latest virus taxonomy at the ICTV website. Aside from formal systems of nomenclature, viruses are often informally grouped into categories based on chemistry, morphology, or other characteristics they share in common. Categories may include naked or enveloped structure, single-stranded (ss) or double-stranded (ds) DNA or ss or ds RNA genomes, segmented or nonsegmented genomes, and positive-strand (+) or negative-strand (−) RNA. For example, herpes viruses can be classified as a dsDNA enveloped virus; human immunodeficiency virus (HIV) is a +ssRNA enveloped virus, and tobacco mosaic virus is a +ssRNA virus. Other characteristics such as host specificity, tissue specificity, capsid shape, and special genes or enzymes may also be used to describe groups of similar viruses. Table 6.2 lists some of the most common viruses that are human pathogens by genome type. Common Pathogenic Viruses Genome Family Example Virus Clinical Features dsDNA, enveloped Poxviridae Orthopoxvirus Skin papules, pustules, lesions Poxviridae Parapoxvirus Skin lesions Herpesviridae Simplexvirus Cold sores, genital herpes, sexually transmitted disease dsDNA, naked Adenoviridae Atadenovirus Respiratory infection (common cold) Papillomaviridae Papillomavirus Genital warts, cervical, vulvar, or vaginal cancer Reoviridae Reovirus Gastroenteritis severe diarrhea (stomach flu) ssDNA, naked Parvoviridae Adeno-associated dependoparvovirus A Respiratory tract infection Parvoviridae Adeno-associated dependoparvovirus B Respiratory tract infection dsRNA, naked Reoviridae Rotavirus Gastroenteritis +ssRNA, naked Picornaviridae Enterovirus C Poliomyelitis Picornaviridae Rhinovirus Upper respiratory tract infection (common cold) Picornaviridae Hepatovirus Hepatitis +ssRNA, enveloped Togaviridae Alphavirus Encephalitis, hemorrhagic fever Togaviridae Rubivirus Rubella Retroviridae Lentivirus Acquired immune deficiency syndrome (AIDS) −ssRNA, enveloped Filoviridae Zaire Ebolavirus Hemorrhagic fever Orthomyxoviridae Influenzavirus A, B, C Flu Rhabdoviridae Lyssavirus Rabies Table 6.2 Check Your Understanding What are the types of virus genomes? Classification of Viral Diseases While the ICTV has been tasked with the biological classification of viruses, it has also played an important role in the classification of diseases caused by viruses. To facilitate the tracking of virus-related human diseases, the ICTV has created classifications that link to the International Classification of Diseases (ICD) , the standard taxonomy of disease that is maintained and updated by the World Health Organization (WHO). The ICD assigns an alphanumeric code of up to six characters to every type of viral infection, as well as all other types of diseases, medical conditions, and causes of death. This ICD code is used in conjunction with two other coding systems (the Current Procedural Terminology, and the Healthcare Common Procedure Coding System) to categorize patient conditions for treatment and insurance reimbursement. For example, when a patient seeks treatment for a viral infection, ICD codes are routinely used by clinicians to order laboratory tests and prescribe treatments specific to the virus suspected of causing the illness. This ICD code is then used by medical laboratories to identify tests that must be performed to confirm the diagnosis. The ICD code is used by the health-care management system to verify that all treatments and laboratory work performed are appropriate for the given virus. Medical coders use ICD codes to assign the proper code for procedures performed, and medical billers, in turn, use this information to process claims for reimbursement by insurance companies. Vital-records keepers use ICD codes to record cause of death on death certificates, and epidemiologists used ICD codes to calculate morbidity and mortality statistics. Check Your Understanding Identify two locations where you would likely find an ICD code. Clinical Focus Part 2 David’s doctor was concerned that his symptoms included prickling and itching at the site of the dog bite; these sensations could be early symptoms of rabies. Several tests are available to diagnose rabies in live patients, but no single antemortem test is adequate. The doctor decided to take samples of David’s blood, saliva, and skin for testing. The skin sample was taken from the nape of the neck (posterior side of the neck near the hairline). It was about 6-mm long and contained at least 10 hair follicles, including the superficial cutaneous nerve. An immunofluorescent staining technique was used on the skin biopsy specimen to detect rabies antibodies in the cutaneous nerves at the base of the hair follicles. A test was also performed on a serum sample from David’s blood to determine whether any antibodies for the rabies virus had been produced. Meanwhile, the saliva sample was used for reverse transcriptase-polymerase chain reaction (RT-PCR) analysis, a test that can detect the presence of viral nucleic acid (RNA). The blood tests came back positive for the presence of rabies virus antigen, prompting David’s doctor to prescribe prophylactic treatment. David is given a series of intramuscular injections of human rabies immunoglobulin along with a series of rabies vaccines. Why does the immunofluorescent technique look for rabies antibodies rather than the rabies virus itself? If David has contracted rabies, what is his prognosis? Jump to the next Clinical Focus box. Go back to the previous Clinical Focus box. 6.2 The Viral Life Cycle Learning Objectives Describe the lytic and lysogenic life cycles Describe the replication process of animal viruses Describe unique characteristics of retroviruses and latent viruses Discuss human viruses and their virus-host cell interactions Explain the process of transduction Describe the replication process of plant viruses All viruses depend on cells for reproduction and metabolic processes. By themselves, viruses do not encode for all of the enzymes necessary for viral replication. But within a host cell, a virus can commandeer cellular machinery to produce more viral particles. Bacteriophages replicate only in the cytoplasm, since prokaryotic cells do not have a nucleus or organelles. In eukaryotic cells, most DNA viruses can replicate inside the nucleus, with an exception observed in the large DNA viruses, such as the poxviruses, that can replicate in the cytoplasm. With a few exceptions, RNA viruses that infect animal cells replicate in the cytoplasm. An important exception that will be highlighted later is Influenza virus. The Life Cycle of Viruses with Prokaryote Hosts The life cycle of bacteriophages has been a good model for understanding how viruses affect the cells they infect, since similar processes have been observed for eukaryotic viruses, which can cause immediate death of the cell or establish a latent or chronic infection. Virulent phages typically lead to the death of the cell through cell lysis. Temperate phages , on the other hand, can become part of a host chromosome and are replicated with the cell genome until such time as they are induced to make newly assembled viruses, or progeny virus es . The Lytic Cycle During the lytic cycle of virulent phage, the bacteriophage takes over the cell, reproduces new phages, and destroys the cell. T-even phage is a good example of a well-characterized class of virulent phages. There are five stages in the bacteriophage lytic cycle (see Figure 6.7 ). Attachment is the first stage in the infection process in which the phage interacts with specific bacterial surface receptors (e.g., lipopolysaccharides and OmpC protein on host surfaces). Most phages have a narrow host range and may infect one species of bacteria or one strain within a species. This unique recognition can be exploited for targeted treatment of bacterial infection by phage therapy or for phage typing to identify unique bacterial subspecies or strains. The second stage of infection is entry or penetration . This occurs through contraction of the tail sheath, which acts like a hypodermic needle to inject the viral genome through the cell wall and membrane. The phage head and remaining components remain outside the bacteria. The third stage of infection is biosynthesis of new viral components. After entering the host cell, the virus synthesizes virus-encoded endonucleases to degrade the bacterial chromosome. It then hijacks the host cell to replicate, transcribe, and translate the necessary viral components (capsomeres, sheath, base plates, tail fibers, and viral enzymes) for the assembly of new viruses. Polymerase genes are usually expressed early in the cycle, while capsid and tail proteins are expressed later. During the maturation phase, new virions are created. To liberate free phages, the bacterial cell wall is disrupted by phage proteins such as holin or lysozyme. The final stage is release. Mature viruses burst out of the host cell in a process called lysis and the progeny viruses are liberated into the environment to infect new cells. The Lysogenic Cycle In a lysogenic cycle , the phage genome also enters the cell through attachment and penetration. A prime example of a phage with this type of life cycle is the lambda phage. During the lysogenic cycle, instead of killing the host, the phage genome integrates into the bacterial chromosome and becomes part of the host. The integrated phage genome is called a prophage . A bacterial host with a prophage is called a lysogen . The process in which a bacterium is infected by a temperate phage is called lysogeny . It is typical of temperate phages to be latent or inactive within the cell. As the bacterium replicates its chromosome, it also replicates the phage’s DNA and passes it on to new daughter cells during reproduction. The presence of the phage may alter the phenotype of the bacterium, since it can bring in extra genes (e.g., toxin genes that can increase bacterial virulence). This change in the host phenotype is called lysogenic conversion or phage conversion . Some bacteria, such as Vibrio cholerae and Clostridium botulinum , are less virulent in the absence of the prophage. The phages infecting these bacteria carry the toxin genes in their genome and enhance the virulence of the host when the toxin genes are expressed. In the case of V. cholera , phage encoded toxin can cause severe diarrhea; in C. botulinum , the toxin can cause paralysis. During lysogeny, the prophage will persist in the host chromosome until induction , which results in the excision of the viral genome from the host chromosome. After induction has occurred the temperate phage can proceed through a lytic cycle and then undergo lysogeny in a newly infected cell (see Figure 6.8 ). Link to Learning This video illustrates the stages of the lysogenic life cycle of a bacteriophage and the transition to a lytic phase. Check Your Understanding Is a latent phage undetectable in a bacterium? Transduction Transduction occurs when a bacteriophage transfers bacterial DNA from one bacterium to another during sequential infections. There are two types of transduction: generalized and specialized transduction. During the lytic cycle of viral replication, the virus hijacks the host cell, degrades the host chromosome, and makes more viral genomes. As it assembles and packages DNA into the phage head, packaging occasionally makes a mistake. Instead of packaging viral DNA, it takes a random piece of host DNA and inserts it into the capsid. Once released, this virion will then inject the former host’s DNA into a newly infected host. The asexual transfer of genetic information can allow for DNA recombination to occur, thus providing the new host with new genes (e.g., an antibiotic-resistance gene, or a sugar-metabolizing gene). Generalized transduction occurs when a random piece of bacterial chromosomal DNA is transferred by the phage during the lytic cycle. Specialized transduction occurs at the end of the lysogenic cycle, when the prophage is excised and the bacteriophage enters the lytic cycle. Since the phage is integrated into the host genome, the prophage can replicate as part of the host. However, some conditions (e.g., ultraviolet light exposure or chemical exposure) stimulate the prophage to undergo induction, causing the phage to excise from the genome, enter the lytic cycle, and produce new phages to leave host cells. During the process of excision from the host chromosome, a phage may occasionally remove some bacterial DNA near the site of viral integration. The phage and host DNA from one end or both ends of the integration site are packaged within the capsid and are transferred to the new, infected host. Since the DNA transferred by the phage is not randomly packaged but is instead a specific piece of DNA near the site of integration, this mechanism of gene transfer is referred to as specialized transduction (see Figure 6.9 ). The DNA can then recombine with host chromosome, giving the latter new characteristics. Transduction seems to play an important role in the evolutionary process of bacteria, giving them a mechanism for asexual exchange of genetic information. Check Your Understanding Which phage life cycle is associated with which forms of transduction? Life Cycle of Viruses with Animal Hosts Lytic animal viruses follow similar infection stages to bacteriophages: attachment, penetration, biosynthesis, maturation, and release (see Figure 6.10 ). However, the mechanisms of penetration, nucleic-acid biosynthesis, and release differ between bacterial and animal viruses. After binding to host receptors, animal viruses enter through endocytosis (engulfment by the host cell) or through membrane fusion (viral envelope with the host cell membrane). Many viruses are host specific, meaning they only infect a certain type of host; and most viruses only infect certain types of cells within tissues. This specificity is called a tissue tropism . Examples of this are demonstrated by the poliovirus , which exhibits tropism for the tissues of the brain and spinal cord, or the influenza virus , which has a primary tropism for the respiratory tract. Animal viruses do not always express their genes using the normal flow of genetic information—from DNA to RNA to protein. Some viruses have a dsDNA genome like cellular organisms and can follow the normal flow. However, others may have ssDNA , dsRNA , or ssRNA genomes. The nature of the genome determines how the genome is replicated and expressed as viral proteins. If a genome is ssDNA, host enzymes will be used to synthesize a second strand that is complementary to the genome strand, thus producing dsDNA. The dsDNA can now be replicated, transcribed, and translated similar to host DNA. If the viral genome is RNA, a different mechanism must be used. There are three types of RNA genome: dsRNA, positive (+) single-strand (+ssRNA) or negative (−) single-strand RNA (−ssRNA) . If a virus has a +ssRNA genome, it can be translated directly to make viral proteins. Viral genomic +ssRNA acts like cellular mRNA. However, if a virus contains a −ssRNA genome, the host ribosomes cannot translate it until the −ssRNA is replicated into +ssRNA by viral RNA-dependent RNA polymerase (RdRP) (see Figure 6.11 ). The RdRP is brought in by the virus and can be used to make +ssRNA from the original −ssRNA genome. The RdRP is also an important enzyme for the replication of dsRNA viruses, because it uses the negative strand of the double-stranded genome as a template to create +ssRNA. The newly synthesized +ssRNA copies can then be translated by cellular ribosomes. An alternative mechanism for viral nucleic acid synthesis is observed in the retrovirus es , which are +ssRNA viruses (see Figure 6.12 ). Single-stranded RNA viruses such as HIV carry a special enzyme called reverse transcriptase within the capsid that synthesizes a complementary ssDNA (cDNA) copy using the +ssRNA genome as a template. The ssDNA is then made into dsDNA, which can integrate into the host chromosome and become a permanent part of the host. The integrated viral genome is called a provirus . The virus now can remain in the host for a long time to establish a chronic infection. The provirus stage is similar to the prophage stage in a bacterial infection during the lysogenic cycle. However, unlike prophage, the provirus does not undergo excision after splicing into the genome. Check Your Understanding Is RNA-dependent RNA polymerase made from a viral gene or a host gene? Persistent Infections Persistent infection occurs when a virus is not completely cleared from the system of the host but stays in certain tissues or organs of the infected person. The virus may remain silent or undergo productive infection without seriously harming or killing the host. Mechanisms of persistent infection may involve the regulation of the viral or host gene expressions or the alteration of the host immune response. The two primary categories of persistent infections are latent infection and chronic infection . Examples of viruses that cause latent infections include herpes simplex virus (oral and genital herpes), varicella-zoster virus (chickenpox and shingles), and Epstein-Barr virus (mononucleosis). Hepatitis C virus and HIV are two examples of viruses that cause long-term chronic infections. Latent Infection Not all animal viruses undergo replication by the lytic cycle. There are viruses that are capable of remaining hidden or dormant inside the cell in a process called latency. These types of viruses are known as latent virus es and may cause latent infections. Viruses capable of latency may initially cause an acute infection before becoming dormant. For example, the varicella-zoster virus infects many cells throughout the body and causes chickenpox , characterized by a rash of blisters covering the skin. About 10 to 12 days postinfection, the disease resolves and the virus goes dormant, living within nerve-cell ganglia for years. During this time, the virus does not kill the nerve cells or continue replicating. It is not clear why the virus stops replicating within the nerve cells and expresses few viral proteins but, in some cases, typically after many years of dormancy, the virus is reactivated and causes a new disease called shingles ( Figure 6.13 ). Whereas chickenpox affects many areas throughout the body, shingles is a nerve cell-specific disease emerging from the ganglia in which the virus was dormant. Latent viruses may remain dormant by existing as circular viral genome molecules outside of the host chromosome. Others become proviruses by integrating into the host genome. During dormancy, viruses do not cause any symptoms of disease and may be difficult to detect. A patient may be unaware that he or she is carrying the virus unless a viral diagnostic test has been performed. Chronic Infection A chronic infection is a disease with symptoms that are recurrent or persistent over a long time. Some viral infections can be chronic if the body is unable to eliminate the virus. HIV is an example of a virus that produces a chronic infection, often after a long period of latency. Once a person becomes infected with HIV, the virus can be detected in tissues continuously thereafter, but untreated patients often experience no symptoms for years. However, the virus maintains chronic persistence through several mechanisms that interfere with immune function, including preventing expression of viral antigens on the surface of infected cells, altering immune cells themselves, restricting expression of viral genes, and rapidly changing viral antigens through mutation. Eventually, the damage to the immune system results in progression of the disease leading to acquired immunodeficiency syndrome (AIDS). The various mechanisms that HIV uses to avoid being cleared by the immune system are also used by other chronically infecting viruses, including the hepatitis C virus. Check Your Understanding In what two ways can a virus manage to maintain a persistent infection? Life Cycle of Viruses with Plant Hosts Plant viruses are more similar to animal viruses than they are to bacteriophages. Plant viruses may be enveloped or non-enveloped. Like many animal viruses, plant viruses can have either a DNA or RNA genome and be single stranded or double stranded. However, most plant viruses do not have a DNA genome; the majority have a +ssRNA genome, which acts like messenger RNA (mRNA). Only a minority of plant viruses have other types of genomes. Plant viruses may have a narrow or broad host range. For example, the citrus tristeza virus infects only a few plants of the Citrus genus, whereas the cucumber mosaic virus infects thousands of plants of various plant families. Most plant viruses are transmitted by contact between plants, or by fungi, nematodes, insects, or other arthropods that act as mechanical vectors. However, some viruses can only be transferred by a specific type of insect vector; for example, a particular virus might be transmitted by aphids but not whiteflies. In some cases, viruses may also enter healthy plants through wounds, as might occur due to pruning or weather damage. Viruses that infect plants are considered biotrophic parasites, which means that they can establish an infection without killing the host, similar to what is observed in the lysogenic life cycles of bacteriophages. Viral infection can be asymptomatic (latent) or can lead to cell death (lytic infection). The life cycle begins with the penetration of the virus into the host cell. Next, the virus is uncoated within the cytoplasm of the cell when the capsid is removed. Depending on the type of nucleic acid, cellular components are used to replicate the viral genome and synthesize viral proteins for assembly of new virions. To establish a systemic infection, the virus must enter a part of the vascular system of the plant, such as the phloem. The time required for systemic infection may vary from a few days to a few weeks depending on the virus, the plant species, and the environmental conditions. The virus life cycle is complete when it is transmitted from an infected plant to a healthy plant. Check Your Understanding What is the structure and genome of a typical plant virus? Viral Growth Curve Unlike the growth curve for a bacterial population, the growth curve for a virus population over its life cycle does not follow a sigmoidal curve. During the initial stage, an inoculum of virus causes infection. In the eclipse phase , viruses bind and penetrate the cells with no virions detected in the medium. The chief difference that next appears in the viral growth curve compared to a bacterial growth curve occurs when virions are released from the lysed host cell at the same time. Such an occurrence is called a burst , and the number of virions per bacterium released is described as the burst size . In a one-step multiplication curve for bacteriophage , the host cells lyse, releasing many viral particles to the medium, which leads to a very steep rise in viral titer (the number of virions per unit volume). If no viable host cells remain, the viral particles begin to degrade during the decline of the culture (see Figure 6.14 ). Check Your Understanding What aspect of the life cycle of a virus leads to the sudden increase in the growth curve? Eye on Ethics Unregistered Treatments Ebola is incurable and deadly. The outbreak in West Africa in 2014 was unprecedented, dwarfing other human Ebola epidemics in the level of mortality. Of 24,666 suspected or confirmed cases reported, 10,179 people died. 9 9 World Health Organization. “WHO Ebola Data and Statistics.” March 18, 2005. http://apps.who.int/gho/data/view.ebola-sitrep.ebola-summary-20150318?lang=en No approved treatments or vaccines for Ebola are available. While some drugs have shown potential in laboratory studies and animal models, they have not been tested in humans for safety and effectiveness. Not only are these drugs untested or unregistered but they are also in short supply. Given the great suffering and high mortality rates, it is fair to ask whether unregistered and untested medications are better than none at all. Should such drugs be dispensed and, if so, who should receive them, in light of their extremely limited supplies? Is it ethical to treat untested drugs on patients with Ebola? On the other hand, is it ethical to withhold potentially life-saving drugs from dying patients? Or should the drugs perhaps be reserved for health-care providers working to contain the disease? In August 2014, two infected US aid workers and a Spanish priest were treated with ZMapp , an unregistered drug that had been tested in monkeys but not in humans. The two American aid workers recovered, but the priest died. Later that month, the WHO released a report on the ethics of treating patients with the drug. Since Ebola is often fatal, the panel reasoned that it is ethical to give the unregistered drugs and unethical to withhold them for safety concerns. This situation is an example of “compassionate use” outside the well-established system of regulation and governance of therapies. Case in Point Ebola in the US On September 24, 2014, Thomas Eric Duncan arrived at the Texas Health Presbyterian Hospital in Dallas complaining of a fever, headache, vomiting, and diarrhea—symptoms commonly observed in patients with the cold or the flu. After examination, an emergency department doctor diagnosed him with sinusitis, prescribed some antibiotics, and sent him home. Two days later, Duncan returned to the hospital by ambulance. His condition had deteriorated and additional blood tests confirmed that he has been infected with the Ebola virus. Further investigations revealed that Duncan had just returned from Liberia, one of the countries in the midst of a severe Ebola epidemic. On September 15, nine days before he showed up at the hospital in Dallas, Duncan had helped transport an Ebola-stricken neighbor to a hospital in Liberia. The hospital continued to treat Duncan, but he died several days after being admitted. The timeline of the Duncan case is indicative of the life cycle of the Ebola virus. The incubation time for Ebola ranges from 2 days to 21 days. Nine days passed between Duncan’s exposure to the virus infection and the appearance of his symptoms. This corresponds, in part, to the eclipse period in the growth of the virus population. During the eclipse phase, Duncan would have been unable to transmit the disease to others. However, once an infected individual begins exhibiting symptoms, the disease becomes very contagious. Ebola virus is transmitted through direct contact with droplets of bodily fluids such as saliva, blood, and vomit. Duncan could conceivably have transmitted the disease to others at any time after he began having symptoms, presumably some time before his arrival at the hospital in Dallas. Once a hospital realizes a patient like Duncan is infected with Ebola virus, the patient is immediately quarantined, and public health officials initiate a back trace to identify everyone with whom a patient like Duncan might have interacted during the period in which he was showing symptoms. Public health officials were able to track down 10 high-risk individuals (family members of Duncan) and 50 low-risk individuals to monitor them for signs of infection. None contracted the disease. However, one of the nurses charged with Duncan’s care did become infected. This, along with Duncan’s initial misdiagnosis, made it clear that US hospitals needed to provide additional training to medical personnel to prevent a possible Ebola outbreak in the US. What types of training can prepare health professionals to contain emerging epidemics like the Ebola outbreak of 2014? What is the difference between a contagious pathogen and an infectious pathogen? Link to Learning For additional information about Ebola, please visit the CDC website. 6.3 Isolation, Culture, and Identification of Viruses Learning Objectives Discuss why viruses were originally described as filterable agents Describe the cultivation of viruses and specimen collection and handling Compare in vivo and in vitro techniques used to cultivate viruses At the beginning of this chapter, we described how porcelain Chamberland filters with pores small enough to allow viruses to pass through were used to discover TMV. Today, porcelain filters have been replaced with membrane filters and other devices used to isolate and identify viruses. Isolation of Viruses Unlike bacteria, many of which can be grown on an artificial nutrient medium, viruses require a living host cell for replication. Infected host cells (eukaryotic or prokaryotic) can be cultured and grown, and then the growth medium can be harvested as a source of virus. Virions in the liquid medium can be separated from the host cells by either centrifugation or filtration. Filters can physically remove anything present in the solution that is larger than the virions; the viruses can then be collected in the filtrate (see Figure 6.16 ). Check Your Understanding What size filter pore is needed to collect a virus? Cultivation of Viruses Viruses can be grown in vivo (within a whole living organism, plant, or animal) or in vitro (outside a living organism in cells in an artificial environment. Flat horizontal cell culture flasks (see Figure 6.17 (a) ) are a common vessel used for in vitro work. Bacteriophages can be grown in the presence of a dense layer of bacteria (also called a bacterial lawn ) grown in a 0.7 % soft agar in a Petri dish or flat (horizontal) flask (see Figure 6.17 (b) ). As the phage kills the bacteria, many plaques are observed among the cloudy bacterial lawn. Animal viruses require cells within a host animal or tissue-culture cells derived from an animal. Animal virus cultivation is important for 1) identification and diagnosis of pathogenic viruses in clinical specimens, 2) production of vaccines, and 3) basic research studies. In vivo host sources can be a developing embryo in an embryonated bird’s egg (e.g., chicken, turkey) or a whole animal. For example, most of the influenza vaccine manufactured for annual flu vaccination programs is cultured in hens’ eggs. The embryo or host animal serves as an incubator for viral replication (see Figure 6.18 ). Location within the embryo or host animal is important. Many viruses have a tissue tropism, and must therefore be introduced into a specific site for growth. Within an embryo, target sites include the amniotic cavity, the chorioallantoic membrane, or the yolk sac. Viral infection may damage tissue membranes, producing lesions called pox; disrupt embryonic development; or cause the death of the embryo. For in vitro studies, various types of cells can be used to support the growth of viruses. A primary cell culture is freshly prepared from animal organs or tissues. Cells are extracted from tissues by mechanical scraping or mincing to release cells or by an enzymatic method using trypsin or collagenase to break up tissue and release single cells into suspension. Because of anchorage-dependence requirements, primary cell cultures require a liquid culture medium in a Petri dish or tissue-culture flask so cells have a solid surface such as glass or plastic for attachment and growth. Primary cultures usually have a limited life span. When cells in a primary culture undergo mitosis and a sufficient density of cells is produced, cells come in contact with other cells. When this cell-to-cell-contact occurs, mitosis is triggered to stop. This is called contact inhibition and it prevents the density of the cells from becoming too high. To prevent contact inhibition, cells from the primary cell culture must be transferred to another vessel with fresh growth medium. This is called a secondary cell culture. Periodically, cell density must be reduced by pouring off some cells and adding fresh medium to provide space and nutrients to maintain cell growth. In contrast to primary cell cultures, continuous cell line s, usually derived from transformed cells or tumors, are often able to be subcultured many times or even grown indefinitely (in which case they are called immortal). Continuous cell lines may not exhibit anchorage dependency (they will grow in suspension) and may have lost their contact inhibition. As a result, continuous cell lines can grow in piles or lumps resembling small tumor growths (see Figure 6.19 ). An example of an immortal cell line is the HeLa cell line , which was originally cultivated from tumor cells obtained from Henrietta Lacks , a patient who died of cervical cancer in 1951. HeLa cells were the first continuous tissue-culture cell line and were used to establish tissue culture as an important technology for research in cell biology, virology, and medicine. Prior to the discovery of HeLa cells, scientists were not able to establish tissue cultures with any reliability or stability. More than six decades later, this cell line is still alive and being used for medical research. See Eye on Ethics: The Immortal Cell Line of Henrietta Lacks to read more about this important cell line and the controversial means by which it was obtained. Check Your Understanding What property of cells makes periodic dilutions of primary cell cultures necessary? Eye on Ethics The Immortal Cell Line of Henrietta Lacks In January 1951, Henrietta Lacks , a 30-year-old African American woman from Baltimore, was diagnosed with cervical cancer at Johns Hopkins Hospital. We now know her cancer was caused by the human papillomavirus (HPV). Cytopathic effects of the virus altered the characteristics of her cells in a process called transformation, which gives the cells the ability to divide continuously. This ability, of course, resulted in a cancerous tumor that eventually killed Mrs. Lacks in October at age 31. Before her death, samples of her cancerous cells were taken without her knowledge or permission. The samples eventually ended up in the possession of Dr. George Gey, a biomedical researcher at Johns Hopkins University. Gey was able to grow some of the cells from Lacks’s sample, creating what is known today as the immortal HeLa cell line . These cells have the ability to live and grow indefinitely and, even today, are still widely used in many areas of research. According to Lacks’s husband, neither Henrietta nor the family gave the hospital permission to collect her tissue specimen. Indeed, the family was not aware until 20 years after Lacks’s death that her cells were still alive and actively being used for commercial and research purposes. Yet HeLa cells have been pivotal in numerous research discoveries related to polio, cancer, and AIDS, among other diseases. The cells have also been commercialized, although they have never themselves been patented. Despite this, Henrietta Lacks’s estate has never benefited from the use of the cells, although, in 2013, the Lacks family was given control over the publication of the genetic sequence of her cells. This case raises several bioethical issues surrounding patients’ informed consent and the right to know. At the time Lacks’s tissues were taken, there were no laws or guidelines about informed consent. Does that mean she was treated fairly at the time? Certainly by today’s standards, the answer would be no. Harvesting tissue or organs from a dying patient without consent is not only considered unethical but illegal, regardless of whether such an act could save other patients’ lives. Is it ethical, then, for scientists to continue to use Lacks’s tissues for research, even though they were obtained illegally by today’s standards? Ethical or not, Lacks’s cells are widely used today for so many applications that it is impossible to list them all. Is this a case in which the ends justify the means? Would Lacks be pleased to know about her contribution to science and the millions of people who have benefited? Would she want her family to be compensated for the commercial products that have been developed using her cells? Or would she feel violated and exploited by the researchers who took part of her body without her consent? Because she was never asked, we will never know. Detection of a Virus Regardless of the method of cultivation, once a virus has been introduced into a whole host organism, embryo, or tissue-culture cell, a sample can be prepared from the infected host, embryo, or cell line for further analysis under a brightfield, electron, or fluorescent microscope. Cytopathic effects (CPEs) are distinct observable cell abnormalities due to viral infection. CPEs can include loss of adherence to the surface of the container, changes in cell shape from flat to round, shrinkage of the nucleus, vacuoles in the cytoplasm, fusion of cytoplasmic membranes and the formation of multinucleated syncytia, inclusion bodies in the nucleus or cytoplasm, and complete cell lysis (see Figure 6.21 ). Further pathological changes include viral disruption of the host genome and altering normal cells into transformed cells, which are the types of cells associated with carcinomas and sarcomas. The type or severity of the CPE depends on the type of virus involved. Figure 6.21 lists CPEs for specific viruses. Link to Learning Watch this video to learn about the effects of viruses on cells. Hemagglutination Assay A serological assay is used to detect the presence of certain types of viruses in patient serum. Serum is the straw-colored liquid fraction of blood plasma from which clotting factors have been removed. Serum can be used in a direct assay called a hemagglutination assay to detect specific types of viruses in the patient’s sample. Hemagglutination is the agglutination (clumping) together of erythrocytes (red blood cells). Many viruses produce surface proteins or spikes called hemagglutinins that can bind to receptors on the membranes of erythrocytes and cause the cells to agglutinate. Hemagglutination is observable without using the microscope, but this method does not always differentiate between infectious and noninfectious viral particles, since both can agglutinate erythrocytes. To identify a specific pathogenic virus using hemagglutination, we must use an indirect approach. Proteins called antibodies, generated by the patient’s immune system to fight a specific virus, can be used to bind to components such as hemagglutinins that are uniquely associated with specific types of viruses. The binding of the antibodies with the hemagglutinins found on the virus subsequently prevent erythrocytes from directly interacting with the virus. So when erythrocytes are added to the antibody-coated viruses, there is no appearance of agglutination; agglutination has been inhibited. We call these types of indirect assays for virus-specific antibodies hemagglutination inhibition (HAI) assays . HAI can be used to detect the presence of antibodies specific to many types of viruses that may be causing or have caused an infection in a patient even months or years after infection (see Figure 6.22 ). This assay is described in greater detail in Agglutination Assays . Check Your Understanding What is the outcome of a positive HIA test? Nucleic Acid Amplification Test Nucleic acid amplification tests (NAAT) are used in molecular biology to detect unique nucleic acid sequences of viruses in patient samples. Polymerase chain reaction (PCR) is an NAAT used to detect the presence of viral DNA in a patient’s tissue or body fluid sample. PCR is a technique that amplifies (i.e., synthesizes many copies) of a viral DNA segment of interest. Using PCR, short nucleotide sequences called primers bind to specific sequences of viral DNA, enabling identification of the virus. Reverse transcriptase-PCR (RT-PCR) is an NAAT used to detect the presence of RNA viruses. RT-PCR differs from PCR in that the enzyme reverse transcriptase (RT) is used to make a cDNA from the small amount of viral RNA in the specimen. The cDNA can then be amplified by PCR. Both PCR and RT-PCR are used to detect and confirm the presence of the viral nucleic acid in patient specimens. Case in Point HPV Scare Michelle, a 21-year-old nursing student, came to the university clinic worried that she might have been exposed to a sexually transmitted disease (STD). Her sexual partner had recently developed several bumps on the base of his penis. He had put off going to the doctor, but Michelle suspects they are genital warts caused by HPV. She is especially concerned because she knows that HPV not only causes warts but is a prominent cause of cervical cancer. She and her partner always use condoms for contraception, but she is not confident that this precaution will protect her from HPV. Michelle’s physician finds no physical signs of genital warts or any other STDs, but recommends that Michelle get a Pap smear along with an HPV test. The Pap smear will screen for abnormal cervical cells and the CPEs associated with HPV; the HPV test will test for the presence of the virus. If both tests are negative, Michelle can be more assured that she most likely has not become infected with HPV. However, her doctor suggests it might be wise for Michelle to get vaccinated against HPV to protect herself from possible future exposure. Why does Michelle’s physician order two different tests instead of relying on one or the other? Enzyme Immunoassay Enzyme immunoassays (EIAs) rely on the ability of antibodies to detect and attach to specific biomolecules called antigens. The detecting antibody attaches to the target antigen with a high degree of specificity in what might be a complex mixture of biomolecules. Also included in this type of assay is a colorless enzyme attached to the detecting antibody. The enzyme acts as a tag on the detecting antibody and can interact with a colorless substrate, leading to the production of a colored end product. EIAs often rely on layers of antibodies to capture and react with antigens, all of which are attached to a membrane filter (see Figure 6.23 ). EIAs for viral antigens are often used as preliminary screening tests. If the results are positive, further confirmation will require tests with even greater sensitivity, such as a western blot or an NAAT . EIAs are discussed in more detail in EIAs and ELISAs . Check Your Understanding What typically indicates a positive EIA test? Clinical Focus Part 3 Along with the RT/PCR analysis, David’s saliva was also collected for viral cultivation. In general, no single diagnostic test is sufficient for antemortem diagnosis, since the results will depend on the sensitivity of the assay, the quantity of virions present at the time of testing, and the timing of the assay, since release of virions in the saliva can vary. As it turns out, the result was negative for viral cultivation from the saliva. This is not surprising to David’s doctor, because one negative result is not an absolute indication of the absence of infection. It may be that the number of virions in the saliva is low at the time of sampling. It is not unusual to repeat the test at intervals to enhance the chance of detecting higher virus loads. Should David’s doctor modify his course of treatment based on these test results? Jump to the next Clinical Focus box. Go back to the previous Clinical Focus box. 6.4 Viroids, Virusoids, and Prions Learning Objectives Describe viroids and their unique characteristics Describe virusoids and their unique characteristics Describe prions and their unique characteristics Research attempts to discover the causative agents of previously uninvestigated diseases have led to the discovery of nonliving disease agents quite different from viruses. These include particles consisting only of RNA or only of protein that, nonetheless, are able to self-propagate at the expense of a host—a key similarity to viruses that allows them to cause disease conditions. To date, these discoveries include viroids, virusoids, and the proteinaceous prions. Viroids In 1971, Theodor Diener , a pathologist working at the Agriculture Research Service, discovered an acellular particle that he named a viroid, meaning “virus-like.” Viroids consist only of a short strand of circular RNA capable of self-replication. The first viroid discovered was found to cause potato tuber spindle disease , which causes slower sprouting and various deformities in potato plants (see Figure 6.24 ). Like viruses, potato spindle tuber viroids (PSTVs) take control of the host machinery to replicate their RNA genome. Unlike viruses, viroids do not have a protein coat to protect their genetic information. Viroids can result in devastating losses of commercially important agricultural food crops grown in fields and orchards. Since the discovery of PSTV, other viroids have been discovered that cause diseases in plants. Tomato planta macho viroid (TPMVd) infects tomato plants, which causes loss of chlorophyll, disfigured and brittle leaves, and very small tomatoes, resulting in loss of productivity in this field crop. Avocado sunblotch viroid (ASBVd) results in lower yields and poorer-quality fruit. ASBVd is the smallest viroid discovered thus far that infects plants. Peach latent mosaic viroid (PLMVd) can cause necrosis of flower buds and branches, and wounding of ripened fruit, which leads to fungal and bacterial growth in the fruit. PLMVd can also cause similar pathological changes in plums, nectarines, apricots, and cherries, resulting in decreased productivity in these orchards, as well. Viroids, in general, can be dispersed mechanically during crop maintenance or harvesting, vegetative reproduction, and possibly via seeds and insects, resulting in a severe drop in food availability and devastating economic consequences. Check Your Understanding What is the genome of a viroid made of? Virusoids A second type of pathogenic RNA that can infect commercially important agricultural crops are the virusoid s , which are subviral particles best described as non–self-replicating ssRNAs. RNA replication of virusoid s is similar to that of viroids but, unlike viroids, virusoids require that the cell also be infected with a specific “helper” virus. There are currently only five described types of virusoids and their associated helper viruses . The helper viruses are all from the family of Sobemoviruses . An example of a helper virus is the subterranean clover mottle virus, which has an associated virusoid packaged inside the viral capsid. Once the helper virus enters the host cell, the virusoids are released and can be found free in plant cell cytoplasm, where they possess ribozyme activity. The helper virus undergoes typical viral replication independent of the activity of the virusoid. The virusoid genomes are small, only 220 to 388 nucleotides long. A virusoid genome does not code for any proteins, but instead serves only to replicate virusoid RNA. Virusoids belong to a larger group of infectious agents called satellite RNA s, which are similar pathogenic RNAs found in animals. Unlike the plant virusoids, satellite RNAs may encode for proteins; however, like plant virusoids, satellite RNAs must coinfect with a helper virus to replicate. One satellite RNA that infects humans and that has been described by some scientists as a virusoid is the hepatitis delta virus (HDV) , which, by some reports, is also called hepatitis delta virusoid. Much larger than a plant virusoid, HDV has a circular, ssRNA genome of 1,700 nucleotides and can direct the biosynthesis of HDV-associated proteins. The HDV helper virus is the hepatitis B virus (HBV) . Coinfection with HBV and HDV results in more severe pathological changes in the liver during infection, which is how HDV was first discovered. Check Your Understanding What is the main difference between a viroid and a virusoid? Prions At one time, scientists believed that any infectious particle must contain DNA or RNA. Then, in 1982, Stanley Prusiner , a medical doctor studying scrapie (a fatal, degenerative disease in sheep) discovered that the disease was caused by proteinaceous infectious particles, or prion s . Because proteins are acellular and do not contain DNA or RNA, Prusiner’s findings were originally met with resistance and skepticism; however, his research was eventually validated, and he received the Nobel Prize in Physiology or Medicine in 1997. A prion is a misfolded rogue form of a normal protein (PrPc) found in the cell. This rogue prion protein (PrPsc), which may be caused by a genetic mutation or occur spontaneously, can be infectious, stimulating other endogenous normal proteins to become misfolded, forming plaques (see Figure 6.25 ). Today, prions are known to cause various forms of transmissible spongiform encephalopathy (TSE) in human and animals. TSE is a rare degenerative disorder that affects the brain and nervous system. The accumulation of rogue proteins causes the brain tissue to become sponge-like, killing brain cells and forming holes in the tissue, leading to brain damage, loss of motor coordination, and dementia (see Figure 6.26 ). Infected individuals are mentally impaired and become unable to move or speak. There is no cure, and the disease progresses rapidly, eventually leading to death within a few months or years. TSEs in humans include kuru , fatal familial insomnia , Gerstmann-Straussler-Scheinker disease , and Creutzfeldt-Jakob disease (see Figure 6.26 ). TSEs in animals include mad cow disease , scrapie (in sheep and goats), and chronic wasting disease (in elk and deer). TSEs can be transmitted between animals and from animals to humans by eating contaminated meat or animal feed. Transmission between humans can occur through heredity (as is often the case with GSS and CJD) or by contact with contaminated tissue, as might occur during a blood transfusion or organ transplant. There is no evidence for transmission via casual contact with an infected person. Table 6.3 lists TSEs that affect humans and their modes of transmission. Transmissible Spongiform Encephalopathies (TSEs) in Humans Disease Mechanism(s) of Transmission 10 10 National Institute of Neurological Disorders and Stroke. “Creutzfeldt-Jakob Disease Fact Sheet.” http://www.ninds.nih.gov/disorders/cjd/detail_cjd.htm (accessed December 31, 2015). Sporadic CJD (sCJD) Not known; possibly by alteration of normal prior protein (PrP) to rogue form due to somatic mutation Variant CJD (vCJD) Eating contaminated cattle products and by secondary bloodborne transmission Familial CJD (fCJD) Mutation in germline PrP gene Iatrogenic CJD (iCJD) Contaminated neurosurgical instruments, corneal graft, gonadotrophic hormone, and, secondarily, by blood transfusion Kuru Eating infected meat through ritualistic cannibalism Gerstmann-Straussler-Scheinker disease (GSS) Mutation in germline PrP gene Fatal familial insomnia (FFI) Mutation in germline PrP gene Table 6.3 Prions are extremely difficult to destroy because they are resistant to heat, chemicals, and radiation. Even standard sterilization procedures do not ensure the destruction of these particles. Currently, there is no treatment or cure for TSE disease, and contaminated meats or infected animals must be handled according to federal guidelines to prevent transmission. Check Your Understanding Does a prion have a genome? Link to Learning For more information on the handling of animals and prion-contaminated materials, visit the guidelines published on the CDC and WHO websites. Clinical Focus Resolution A few days later, David’s doctor receives the results of the immunofluorescence test on his skin sample. The test is negative for rabies antigen. A second viral antigen test on his saliva sample also comes back negative. Despite these results, the doctor decides to continue David’s current course of treatment. Given the positive RT-PCR test, it is best not to rule out a possible rabies infection. Near the site of the bite, David receives an injection of rabies immunoglobulin, which attaches to and inactivates any rabies virus that may be present in his tissues. Over the next 14 days, he receives a series of four rabies-specific vaccinations in the arm. These vaccines activate David’s immune response and help his body recognize and fight the virus. Thankfully, with treatment, David symptoms improve and he makes a full recovery. Not all rabies cases have such a fortunate outcome. In fact, rabies is usually fatal once the patient starts to exhibit symptoms, and postbite treatments are mainly palliative (i.e., sedation and pain management). Go back to the previous Clinical Focus box.
anatomy_and_physiology
Chapter Objectives After studying this chapter, you will be able to: List the structures of the respiratory system List the major functions of the respiratory system Outline the forces that allow for air movement into and out of the lungs Outline the process of gas exchange Summarize the process of oxygen and carbon dioxide transport within the respiratory system Create a flow chart illustrating how respiration is controlled Discuss how the respiratory system responds to exercise Describe the development of the respiratory system in the embryo Introduction Hold your breath. Really! See how long you can hold your breath as you continue reading…How long can you do it? Chances are you are feeling uncomfortable already. A typical human cannot survive without breathing for more than 3 minutes, and even if you wanted to hold your breath longer, your autonomic nervous system would take control. This is because every cell in the body needs to run the oxidative stages of cellular respiration, the process by which energy is produced in the form of adenosine triphosphate (ATP). For oxidative phosphorylation to occur, oxygen is used as a reactant and carbon dioxide is released as a waste product. You may be surprised to learn that although oxygen is a critical need for cells, it is actually the accumulation of carbon dioxide that primarily drives your need to breathe. Carbon dioxide is exhaled and oxygen is inhaled through the respiratory system, which includes muscles to move air into and out of the lungs, passageways through which air moves, and microscopic gas exchange surfaces covered by capillaries. The circulatory system transports gases from the lungs to tissues throughout the body and vice versa. A variety of diseases can affect the respiratory system, such as asthma, emphysema, chronic obstruction pulmonary disorder (COPD), and lung cancer. All of these conditions affect the gas exchange process and result in labored breathing and other difficulties.
[ { "answer": { "ans_choice": 0, "ans_text": "increase surface area" }, "bloom": "1", "hl_context": "The external nose consists of the surface and skeletal structures that result in the outward appearance of the nose and contribute to its numerous functions ( Figure 22.3 ) . The root is the region of the nose located between the eyebrows . The bridge is the part of the nose that connects the root to the rest of the nose . The dorsum nasi is the length of the nose . The apex is the tip of the nose . On either side of the apex , the nostrils are formed by the alae ( singular = ala ) . An ala is a cartilaginous structure that forms the lateral side of each naris ( plural = nares ) , or nostril opening . The philtrum is the concave surface that connects the apex of the nose to the upper lip . Underneath the thin skin of the nose are its skeletal features ( see Figure 22.3 , lower illustration ) . While the root and bridge of the nose consist of bone , the protruding portion of the nose is composed of cartilage . As a result , when looking at a skull , the nose is missing . The nasal bone is one of a pair of bones that lies under the root and bridge of the nose . The nasal bone articulates superiorly with the frontal bone and laterally with the maxillary bones . Septal cartilage is flexible hyaline cartilage connected to the nasal bone , forming the dorsum nasi . The alar cartilage consists of the apex of the nose ; it surrounds the naris . The nares open into the nasal cavity , which is separated into left and right sections by the nasal septum ( Figure 22.4 ) . The nasal septum is formed anteriorly by a portion of the septal cartilage ( the flexible portion you can touch with your fingers ) and posteriorly by the perpendicular plate of the ethmoid bone ( a cranial bone located just posterior to the nasal bones ) and the thin vomer bones ( whose name refers to its plough shape ) . Each lateral wall of the nasal cavity has three bony projections , called the superior , middle , and inferior nasal conchae . The inferior conchae are separate bones , whereas the superior and middle conchae are portions of the ethmoid bone . <hl> Conchae serve to increase the surface area of the nasal cavity and to disrupt the flow of air as it enters the nose , causing air to bounce along the epithelium , where it is cleaned and warmed . <hl> The conchae and meatuses also conserve water and prevent dehydration of the nasal epithelium by trapping water during exhalation . The floor of the nasal cavity is composed of the palate . The hard palate at the anterior region of the nasal cavity is composed of bone . The soft palate at the posterior portion of the nasal cavity consists of muscle tissue . Air exits the nasal cavities via the internal nares and moves into the pharynx .", "hl_sentences": "Conchae serve to increase the surface area of the nasal cavity and to disrupt the flow of air as it enters the nose , causing air to bounce along the epithelium , where it is cleaned and warmed .", "question": { "cloze_format": "The function of the conchae in the nasal cavity is to ___ .", "normal_format": "What is the function of the conchae in the nasal cavity?", "question_choices": [ "increase surface area", "exchange gases", "maintain surface tension", "maintain air pressure" ], "question_id": "fs-id1983853", "question_text": "What is the function of the conchae in the nasal cavity?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 3, "ans_text": "oral cavity" }, "bloom": "1", "hl_context": "The oropharynx is a passageway for both air and food . The oropharynx is bordered superiorly by the nasopharynx and anteriorly by the oral cavity . <hl> The fauces is the opening at the connection between the oral cavity and the oropharynx . <hl> As the nasopharynx becomes the oropharynx , the epithelium changes from pseudostratified ciliated columnar epithelium to stratified squamous epithelium . The oropharynx contains two distinct sets of tonsils , the palatine and lingual tonsils . A palatine tonsil is one of a pair of structures located laterally in the oropharynx in the area of the fauces . The lingual tonsil is located at the base of the tongue . Similar to the pharyngeal tonsil , the palatine and lingual tonsils are composed of lymphoid tissue , and trap and destroy pathogens entering the body through the oral or nasal cavities .", "hl_sentences": "The fauces is the opening at the connection between the oral cavity and the oropharynx .", "question": { "cloze_format": "The fauces connects ___ structures to the oropharynx.", "normal_format": "The fauces connects which of the following structures to the oropharynx?", "question_choices": [ "nasopharynx", "laryngopharynx", "nasal cavity", "oral cavity" ], "question_id": "fs-id2486872", "question_text": "The fauces connects which of the following structures to the oropharynx?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 0, "ans_text": "C-shaped cartilage" }, "bloom": "1", "hl_context": "Trachea The trachea ( windpipe ) extends from the larynx toward the lungs ( Figure 22.9 a ) . <hl> The trachea is formed by 16 to 20 stacked , C-shaped pieces of hyaline cartilage that are connected by dense connective tissue . <hl> The trachealis muscle and elastic connective tissue together form the fibroelastic membrane , a flexible membrane that closes the posterior surface of the trachea , connecting the C-shaped cartilages . The fibroelastic membrane allows the trachea to stretch and expand slightly during inhalation and exhalation , whereas the rings of cartilage provide structural support and prevent the trachea from collapsing . In addition , the trachealis muscle can be contracted to force air through the trachea during exhalation . The trachea is lined with pseudostratified ciliated columnar epithelium , which is continuous with the larynx . The esophagus borders the trachea posteriorly .", "hl_sentences": "The trachea is formed by 16 to 20 stacked , C-shaped pieces of hyaline cartilage that are connected by dense connective tissue .", "question": { "cloze_format": "___ are structural features of the trachea.", "normal_format": "Which of the following are structural features of the trachea?", "question_choices": [ "C-shaped cartilage", "smooth muscle fibers", "cilia", "all of the above" ], "question_id": "fs-id2311072", "question_text": "Which of the following are structural features of the trachea?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 2, "ans_text": "to remove pathogens and debris" }, "bloom": "1", "hl_context": "An alveolar sac is a cluster of many individual alveoli that are responsible for gas exchange . An alveolus is approximately 200 μm in diameter with elastic walls that allow the alveolus to stretch during air intake , which greatly increases the surface area available for gas exchange . Alveoli are connected to their neighbors by alveolar pores , which help maintain equal air pressure throughout the alveoli and lung ( Figure 22.11 ) . The alveolar wall consists of three major cell types : type I alveolar cells , type II alveolar cells , and alveolar macrophages . A type I alveolar cell is a squamous epithelial cell of the alveoli , which constitute up to 97 percent of the alveolar surface area . These cells are about 25 nm thick and are highly permeable to gases . A type II alveolar cell is interspersed among the type I cells and secretes pulmonary surfactant , a substance composed of phospholipids and proteins that reduces the surface tension of the alveoli . <hl> Roaming around the alveolar wall is the alveolar macrophage , a phagocytic cell of the immune system that removes debris and pathogens that have reached the alveoli . <hl>", "hl_sentences": "Roaming around the alveolar wall is the alveolar macrophage , a phagocytic cell of the immune system that removes debris and pathogens that have reached the alveoli .", "question": { "cloze_format": "The role of alveolar macrophages is ___.", "normal_format": "What is the role of alveolar macrophages?", "question_choices": [ "to secrete pulmonary surfactant", "to secrete antimicrobial proteins", "to remove pathogens and debris", "to facilitate gas exchange" ], "question_id": "fs-id2093382", "question_text": "What is the role of alveolar macrophages?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 1, "ans_text": "fissure" }, "bloom": "1", "hl_context": "<hl> Each lung is composed of smaller units called lobes . <hl> <hl> Fissures separate these lobes from each other . <hl> The right lung consists of three lobes : the superior , middle , and inferior lobes . The left lung consists of two lobes : the superior and inferior lobes . A bronchopulmonary segment is a division of a lobe , and each lobe houses multiple bronchopulmonary segments . Each segment receives air from its own tertiary bronchus and is supplied with blood by its own artery . Some diseases of the lungs typically affect one or more bronchopulmonary segments , and in some cases , the diseased segments can be surgically removed with little influence on neighboring segments . A pulmonary lobule is a subdivision formed as the bronchi branch into bronchioles . Each lobule receives its own large bronchiole that has multiple branches . An interlobular septum is a wall , composed of connective tissue , which separates lobules from one another .", "hl_sentences": "Each lung is composed of smaller units called lobes . Fissures separate these lobes from each other .", "question": { "cloze_format": "The structures that separates the lung into lobes is ___.", "normal_format": "Which of the following structures separates the lung into lobes?", "question_choices": [ "mediastinum", "fissure", "root", "pleura" ], "question_id": "fs-id2614454", "question_text": "Which of the following structures separates the lung into lobes?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 0, "ans_text": "bronchopulmonary segment" }, "bloom": "1", "hl_context": "Each lung is composed of smaller units called lobes . Fissures separate these lobes from each other . The right lung consists of three lobes : the superior , middle , and inferior lobes . The left lung consists of two lobes : the superior and inferior lobes . <hl> A bronchopulmonary segment is a division of a lobe , and each lobe houses multiple bronchopulmonary segments . <hl> <hl> Each segment receives air from its own tertiary bronchus and is supplied with blood by its own artery . <hl> Some diseases of the lungs typically affect one or more bronchopulmonary segments , and in some cases , the diseased segments can be surgically removed with little influence on neighboring segments . A pulmonary lobule is a subdivision formed as the bronchi branch into bronchioles . Each lobule receives its own large bronchiole that has multiple branches . An interlobular septum is a wall , composed of connective tissue , which separates lobules from one another .", "hl_sentences": "A bronchopulmonary segment is a division of a lobe , and each lobe houses multiple bronchopulmonary segments . Each segment receives air from its own tertiary bronchus and is supplied with blood by its own artery .", "question": { "cloze_format": "A section of the lung that receives its own tertiary bronchus is called the ________.", "normal_format": "What is a section of the lung that receives its own tertiary bronchus called?", "question_choices": [ "bronchopulmonary segment", "pulmonary lobule", "interpulmonary segment", "respiratory segment" ], "question_id": "fs-id2112277", "question_text": "A section of the lung that receives its own tertiary bronchus is called the ________." }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 2, "ans_text": "respiratory" }, "bloom": "1", "hl_context": "<hl> The purpose of the respiratory system is to perform gas exchange . <hl> Pulmonary ventilation provides air to the alveoli for this gas exchange process . At the respiratory membrane , where the alveolar and capillary walls meet , gases move across the membranes , with oxygen entering the bloodstream and carbon dioxide exiting . <hl> It is through this mechanism that blood is oxygenated and carbon dioxide , the waste product of cellular respiration , is removed from the body . <hl> <hl> The major organs of the respiratory system function primarily to provide oxygen to body tissues for cellular respiration , remove the waste product carbon dioxide , and help to maintain acid-base balance . <hl> Portions of the respiratory system are also used for non-vital functions , such as sensing odors , speech production , and for straining , such as during childbirth or coughing ( Figure 22.2 ) .", "hl_sentences": "The purpose of the respiratory system is to perform gas exchange . It is through this mechanism that blood is oxygenated and carbon dioxide , the waste product of cellular respiration , is removed from the body . The major organs of the respiratory system function primarily to provide oxygen to body tissues for cellular respiration , remove the waste product carbon dioxide , and help to maintain acid-base balance .", "question": { "cloze_format": "The ________ circulation picks up oxygen for cellular use and drops off carbon dioxide for removal from the body.", "normal_format": "Which circulation picks up oxygen for cellular use and drops off carbon dioxide for removal from the body?", "question_choices": [ "pulmonary", "interlobular", "respiratory", "bronchial" ], "question_id": "fs-id2321808", "question_text": "The ________ circulation picks up oxygen for cellular use and drops off carbon dioxide for removal from the body." }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 0, "ans_text": "pulmonary ventilation" }, "bloom": "1", "hl_context": "<hl> Pulmonary ventilation is dependent on three types of pressure : atmospheric , intra-alveolar , and intrapleural . <hl> Atmospheric pressure is the amount of force that is exerted by gases in the air surrounding any given surface , such as the body . Atmospheric pressure can be expressed in terms of the unit atmosphere , abbreviated atm , or in millimeters of mercury ( mm Hg ) . One atm is equal to 760 mm Hg , which is the atmospheric pressure at sea level . Typically , for respiration , other pressure values are discussed in relation to atmospheric pressure . Therefore , negative pressure is pressure lower than the atmospheric pressure , whereas positive pressure is pressure that it is greater than the atmospheric pressure . A pressure that is equal to the atmospheric pressure is expressed as zero . Intra-alveolar pressure ( intrapulmonary pressure ) is the pressure of the air within the alveoli , which changes during the different phases of breathing ( Figure 22.16 ) . Because the alveoli are connected to the atmosphere via the tubing of the airways ( similar to the two - and one-liter containers in the example above ) , the intrapulmonary pressure of the alveoli always equalizes with the atmospheric pressure . Intrapleural pressure is the pressure of the air within the pleural cavity , between the visceral and parietal pleurae . Similar to intra-alveolar pressure , intrapleural pressure also changes during the different phases of breathing . However , due to certain characteristics of the lungs , the intrapleural pressure is always lower than , or negative to , the intra-alveolar pressure ( and therefore also to atmospheric pressure ) . Although it fluctuates during inspiration and expiration , intrapleural pressure remains approximately – 4 mm Hg throughout the breathing cycle . <hl> Pulmonary ventilation is the act of breathing , which can be described as the movement of air into and out of the lungs . <hl> <hl> The major mechanisms that drive pulmonary ventilation are atmospheric pressure ( P atm ); the air pressure within the alveoli , called intra-alveolar pressure ( P alv ); and the pressure within the pleural cavity , called intrapleural pressure ( P ip ) . <hl> Mechanisms of Breathing", "hl_sentences": "Pulmonary ventilation is dependent on three types of pressure : atmospheric , intra-alveolar , and intrapleural . Pulmonary ventilation is the act of breathing , which can be described as the movement of air into and out of the lungs . The major mechanisms that drive pulmonary ventilation are atmospheric pressure ( P atm ); the air pressure within the alveoli , called intra-alveolar pressure ( P alv ); and the pressure within the pleural cavity , called intrapleural pressure ( P ip ) .", "question": { "cloze_format": "Atmospheric pressure play a role in is the ___ process.", "normal_format": "Which of the following processes does atmospheric pressure play a role in?", "question_choices": [ "pulmonary ventilation", "production of pulmonary surfactant", "resistance", "surface tension" ], "question_id": "fs-id1748683", "question_text": "Which of the following processes does atmospheric pressure play a role in?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 2, "ans_text": "increase in" }, "bloom": "1", "hl_context": "Inspiration ( or inhalation ) and expiration ( or exhalation ) are dependent on the differences in pressure between the atmosphere and the lungs . In a gas , pressure is a force created by the movement of gas molecules that are confined . For example , a certain number of gas molecules in a two-liter container has more room than the same number of gas molecules in a one-liter container ( Figure 22.15 ) . In this case , the force exerted by the movement of the gas molecules against the walls of the two-liter container is lower than the force exerted by the gas molecules in the one-liter container . Therefore , the pressure is lower in the two-liter container and higher in the one-liter container . At a constant temperature , changing the volume occupied by the gas changes the pressure , as does changing the number of gas molecules . Boyle ’ s law describes the relationship between volume and pressure in a gas at a constant temperature . <hl> Boyle discovered that the pressure of a gas is inversely proportional to its volume : If volume increases , pressure decreases . <hl> <hl> Likewise , if volume decreases , pressure increases . <hl> Pressure and volume are inversely related ( P = k / V ) . Therefore , the pressure in the one-liter container ( one-half the volume of the two-liter container ) would be twice the pressure in the two-liter container . Boyle ’ s law is expressed by the following formula :", "hl_sentences": "Boyle discovered that the pressure of a gas is inversely proportional to its volume : If volume increases , pressure decreases . Likewise , if volume decreases , pressure increases .", "question": { "cloze_format": "A decrease in volume leads to a(n) ________ pressure.", "normal_format": "When volume decreases, what happens to pressure?", "question_choices": [ "decrease in", "equalization of", "increase in", "zero" ], "question_id": "fs-id2568609", "question_text": "A decrease in volume leads to a(n) ________ pressure." }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 3, "ans_text": "transpulmonary pressure" }, "bloom": null, "hl_context": "Competing forces within the thorax cause the formation of the negative intrapleural pressure . One of these forces relates to the elasticity of the lungs themselves — elastic tissue pulls the lungs inward , away from the thoracic wall . Surface tension of alveolar fluid , which is mostly water , also creates an inward pull of the lung tissue . This inward tension from the lungs is countered by opposing forces from the pleural fluid and thoracic wall . Surface tension within the pleural cavity pulls the lungs outward . Too much or too little pleural fluid would hinder the creation of the negative intrapleural pressure ; therefore , the level must be closely monitored by the mesothelial cells and drained by the lymphatic system . Since the parietal pleura is attached to the thoracic wall , the natural elasticity of the chest wall opposes the inward pull of the lungs . Ultimately , the outward pull is slightly greater than the inward pull , creating the – 4 mm Hg intrapleural pressure relative to the intra-alveolar pressure . <hl> Transpulmonary pressure is the difference between the intrapleural and intra-alveolar pressures , and it determines the size of the lungs . <hl> A higher transpulmonary pressure corresponds to a larger lung .", "hl_sentences": "Transpulmonary pressure is the difference between the intrapleural and intra-alveolar pressures , and it determines the size of the lungs .", "question": { "cloze_format": "The pressure difference between the intra-alveolar and intrapleural pressures is called ________.", "normal_format": "What is the pressure difference between the intra-alveolar and intrapleural pressures called?", "question_choices": [ "atmospheric pressure", "pulmonary pressure", "negative pressure", "transpulmonary pressure" ], "question_id": "fs-id2502141", "question_text": "The pressure difference between the intra-alveolar and intrapleural pressures is called ________." }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 0, "ans_text": "resistance" }, "bloom": "1", "hl_context": "Other characteristics of the lungs influence the effort that must be expended to ventilate . <hl> Resistance is a force that slows motion , in this case , the flow of gases . <hl> The size of the airway is the primary factor affecting resistance . A small tubular diameter forces air through a smaller space , causing more collisions of air molecules with the walls of the airways . The following formula helps to describe the relationship between airway resistance and pressure changes :", "hl_sentences": "Resistance is a force that slows motion , in this case , the flow of gases .", "question": { "cloze_format": "Gas flow decreases as ________ increases.", "normal_format": "Gas flow decreases as what increases?", "question_choices": [ "resistance", "pressure", "airway diameter", "friction" ], "question_id": "fs-id2353220", "question_text": "Gas flow decreases as ________ increases." }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 3, "ans_text": "The ribs and sternum move upward." }, "bloom": "3", "hl_context": "Pulmonary ventilation comprises two major steps : inspiration and expiration . Inspiration is the process that causes air to enter the lungs , and expiration is the process that causes air to leave the lungs ( Figure 22.17 ) . A respiratory cycle is one sequence of inspiration and expiration . In general , two muscle groups are used during normal inspiration : the diaphragm and the external intercostal muscles . Additional muscles can be used if a bigger breath is required . When the diaphragm contracts , it moves inferiorly toward the abdominal cavity , creating a larger thoracic cavity and more space for the lungs . <hl> Contraction of the external intercostal muscles moves the ribs upward and outward , causing the rib cage to expand , which increases the volume of the thoracic cavity . <hl> Due to the adhesive force of the pleural fluid , the expansion of the thoracic cavity forces the lungs to stretch and expand as well . This increase in volume leads to a decrease in intra-alveolar pressure , creating a pressure lower than atmospheric pressure . As a result , a pressure gradient is created that drives air into the lungs .", "hl_sentences": "Contraction of the external intercostal muscles moves the ribs upward and outward , causing the rib cage to expand , which increases the volume of the thoracic cavity .", "question": { "cloze_format": "Contraction of the external intercostal muscles causes ___ .", "normal_format": "Contraction of the external intercostal muscles causes which of the following to occur?", "question_choices": [ "The diaphragm moves downward.", "The rib cage is compressed.", "The thoracic cavity volume decreases.", "The ribs and sternum move upward." ], "question_id": "fs-id2304737", "question_text": "Contraction of the external intercostal muscles causes which of the following to occur?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 0, "ans_text": "residual volume" }, "bloom": "1", "hl_context": "Respiratory volume is the term used for various volumes of air moved by or associated with the lungs at a given point in the respiratory cycle . There are four major types of respiratory volumes : tidal , residual , inspiratory reserve , and expiratory reserve ( Figure 22.18 ) . Tidal volume ( TV ) is the amount of air that normally enters the lungs during quiet breathing , which is about 500 milliliters . Expiratory reserve volume ( ERV ) is the amount of air you can forcefully exhale past a normal tidal expiration , up to 1200 milliliters for men . Inspiratory reserve volume ( IRV ) is produced by a deep inhalation , past a tidal inspiration . This is the extra volume that can be brought into the lungs during a forced inspiration . Residual volume ( RV ) is the air left in the lungs if you exhale as much air as possible . <hl> The residual volume makes breathing easier by preventing the alveoli from collapsing . <hl> Respiratory volume is dependent on a variety of factors , and measuring the different types of respiratory volumes can provide important clues about a person ’ s respiratory health ( Figure 22.19 ) .", "hl_sentences": "The residual volume makes breathing easier by preventing the alveoli from collapsing .", "question": { "cloze_format": "The ___ prevents the alveoli from collapsing.", "normal_format": "Which of the following prevents the alveoli from collapsing?", "question_choices": [ "residual volume", "tidal volume", "expiratory reserve volume", "inspiratory reserve volume" ], "question_id": "fs-id1234182", "question_text": "Which of the following prevents the alveoli from collapsing?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 3, "ans_text": "high; low" }, "bloom": "1", "hl_context": "Table 22.2 Partial pressure is extremely important in predicting the movement of gases . Recall that gases tend to equalize their pressure in two regions that are connected . <hl> A gas will move from an area where its partial pressure is higher to an area where its partial pressure is lower . <hl> In addition , the greater the partial pressure difference between the two areas , the more rapid is the movement of gases .", "hl_sentences": "A gas will move from an area where its partial pressure is higher to an area where its partial pressure is lower .", "question": { "cloze_format": "Gas moves from an area of ________ partial pressure to an area of ________ partial pressure.", "normal_format": "From which area of partial pressure to which area of partial pressure does gas moves?", "question_choices": [ "low; high", "low; low", "high; high", "high; low" ], "question_id": "fs-id2347595", "question_text": "Gas moves from an area of ________ partial pressure to an area of ________ partial pressure." }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 0, "ans_text": "The capillary constricts." }, "bloom": "1", "hl_context": "The partial pressure of oxygen in alveolar air is about 104 mm Hg , whereas the partial pressure of oxygenated blood in pulmonary veins is about 100 mm Hg . When ventilation is sufficient , oxygen enters the alveoli at a high rate , and the partial pressure of oxygen in the alveoli remains high . In contrast , when ventilation is insufficient , the partial pressure of oxygen in the alveoli drops . Without the large difference in partial pressure between the alveoli and the blood , oxygen does not diffuse efficiently across the respiratory membrane . The body has mechanisms that counteract this problem . <hl> In cases when ventilation is not sufficient for an alveolus , the body redirects blood flow to alveoli that are receiving sufficient ventilation . <hl> <hl> This is achieved by constricting the pulmonary arterioles that serves the dysfunctional alveolus , which redirects blood to other alveoli that have sufficient ventilation . <hl> At the same time , the pulmonary arterioles that serve alveoli receiving sufficient ventilation vasodilate , which brings in greater blood flow . Factors such as carbon dioxide , oxygen , and pH levels can all serve as stimuli for adjusting blood flow in the capillary networks associated with the alveoli . Ventilation is regulated by the diameter of the airways , whereas perfusion is regulated by the diameter of the blood vessels . The diameter of the bronchioles is sensitive to the partial pressure of carbon dioxide in the alveoli . A greater partial pressure of carbon dioxide in the alveoli causes the bronchioles to increase their diameter as will a decreased level of oxygen in the blood supply , allowing carbon dioxide to be exhaled from the body at a greater rate . As mentioned above , a greater partial pressure of oxygen in the alveoli causes the pulmonary arterioles to dilate , increasing blood flow .", "hl_sentences": "In cases when ventilation is not sufficient for an alveolus , the body redirects blood flow to alveoli that are receiving sufficient ventilation . This is achieved by constricting the pulmonary arterioles that serves the dysfunctional alveolus , which redirects blood to other alveoli that have sufficient ventilation .", "question": { "cloze_format": "When ventilation is not sufficient, it occurs that ___.", "normal_format": "When ventilation is not sufficient, which of the following occurs?", "question_choices": [ "The capillary constricts.", "The capillary dilates.", "The partial pressure of oxygen in the affected alveolus increases.", "The bronchioles dilate." ], "question_id": "fs-id2228521", "question_text": "When ventilation is not sufficient, which of the following occurs?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 2, "ans_text": "internal respiration" }, "bloom": "1", "hl_context": "<hl> Internal respiration is gas exchange that occurs at the level of body tissues ( Figure 22.23 ) . <hl> Similar to external respiration , internal respiration also occurs as simple diffusion due to a partial pressure gradient . However , the partial pressure gradients are opposite of those present at the respiratory membrane . The partial pressure of oxygen in tissues is low , about 40 mm Hg , because oxygen is continuously used for cellular respiration . In contrast , the partial pressure of oxygen in the blood is about 100 mm Hg . This creates a pressure gradient that causes oxygen to dissociate from hemoglobin , diffuse out of the blood , cross the interstitial space , and enter the tissue . Hemoglobin that has little oxygen bound to it loses much of its brightness , so that blood returning to the heart is more burgundy in color . Gas exchange occurs at two sites in the body : in the lungs , where oxygen is picked up and carbon dioxide is released at the respiratory membrane , and at the tissues , where oxygen is released and carbon dioxide is picked up . External respiration is the exchange of gases with the external environment , and occurs in the alveoli of the lungs . <hl> Internal respiration is the exchange of gases with the internal environment , and occurs in the tissues . <hl> The actual exchange of gases occurs due to simple diffusion . Energy is not required to move oxygen or carbon dioxide across membranes . Instead , these gases follow pressure gradients that allow them to diffuse . The anatomy of the lung maximizes the diffusion of gases : The respiratory membrane is highly permeable to gases ; the respiratory and blood capillary membranes are very thin ; and there is a large surface area throughout the lungs .", "hl_sentences": "Internal respiration is gas exchange that occurs at the level of body tissues ( Figure 22.23 ) . Internal respiration is the exchange of gases with the internal environment , and occurs in the tissues .", "question": { "cloze_format": "Gas exchange that occurs at the level of the tissues is called ________.", "normal_format": "What is gas exchange that occurs at the level of the tissues called?", "question_choices": [ "external respiration", "interpulmonary respiration", "internal respiration", "pulmonary ventilation" ], "question_id": "fs-id2602080", "question_text": "Gas exchange that occurs at the level of the tissues is called ________." }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 2, "ans_text": "hemoglobin and oxygen" }, "bloom": "1", "hl_context": "Even though oxygen is transported via the blood , you may recall that oxygen is not very soluble in liquids . A small amount of oxygen does dissolve in the blood and is transported in the bloodstream , but it is only about 1.5 % of the total amount . The majority of oxygen molecules are carried from the lungs to the body ’ s tissues by a specialized transport system , which relies on the erythrocyte — the red blood cell . Erythrocytes contain a metalloprotein , hemoglobin , which serves to bind oxygen molecules to the erythrocyte ( Figure 22.25 ) . Heme is the portion of hemoglobin that contains iron , and it is heme that binds oxygen . Each hemoglobin molecule contains four iron-containing heme molecules , and because of this , one hemoglobin molecule is capable of carrying up to four molecules of oxygen . As oxygen diffuses across the respiratory membrane from the alveolus to the capillary , it also diffuses into the red blood cell and is bound by hemoglobin . <hl> The following reversible chemical reaction describes the production of the final product , oxyhemoglobin ( HbO 2 ) , which is formed when oxygen binds to hemoglobin . <hl> Oxyhemoglobin is a bright red-colored molecule that contributes to the bright red color of oxygenated blood .", "hl_sentences": "The following reversible chemical reaction describes the production of the final product , oxyhemoglobin ( HbO 2 ) , which is formed when oxygen binds to hemoglobin .", "question": { "cloze_format": "Oxyhemoglobin forms by a chemical reaction between ___.", "normal_format": "Oxyhemoglobin forms by a chemical reaction between which of the following?", "question_choices": [ "hemoglobin and carbon dioxide", "carbonic anhydrase and carbon dioxide", "hemoglobin and oxygen", "carbonic anhydrase and oxygen" ], "question_id": "fs-id2585421", "question_text": "Oxyhemoglobin forms by a chemical reaction between which of the following?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 3, "ans_text": "all of the above" }, "bloom": null, "hl_context": "<hl> The pH of the blood is another factor that influences the oxygen – hemoglobin saturation / dissociation curve ( see Figure 22.26 ) . <hl> The Bohr effect is a phenomenon that arises from the relationship between pH and oxygen ’ s affinity for hemoglobin : A lower , more acidic pH promotes oxygen dissociation from hemoglobin . In contrast , a higher , or more basic , pH inhibits oxygen dissociation from hemoglobin . The greater the amount of carbon dioxide in the blood , the more molecules that must be converted , which in turn generates hydrogen ions and thus lowers blood pH . Furthermore , blood pH may become more acidic when certain byproducts of cell metabolism , such as lactic acid , carbonic acid , and carbon dioxide , are released into the bloodstream . <hl> Factors other than partial pressure also affect the oxygen – hemoglobin saturation / dissociation curve . <hl> <hl> For example , a higher temperature promotes hemoglobin and oxygen to dissociate faster , whereas a lower temperature inhibits dissociation ( see Figure 22.26 , middle ) . <hl> However , the human body tightly regulates temperature , so this factor may not affect gas exchange throughout the body . The exception to this is in highly active tissues , which may release a larger amount of energy than is given off as heat . As a result , oxygen readily dissociates from hemoglobin , which is a mechanism that helps to provide active tissues with more oxygen . <hl> Certain hormones , such as androgens , epinephrine , thyroid hormones , and growth hormone , can affect the oxygen – hemoglobin saturation / disassociation curve by stimulating the production of a compound called 2,3- bisphosphoglycerate ( BPG ) by erythrocytes . <hl> BPG is a byproduct of glycolysis . Because erythrocytes do not contain mitochondria , glycolysis is the sole method by which these cells produce ATP . BPG promotes the disassociation of oxygen from hemoglobin . Therefore , the greater the concentration of BPG , the more readily oxygen dissociates from hemoglobin , despite its partial pressure . Partial pressure is an important aspect of the binding of oxygen to and disassociation from heme . An oxygen – hemoglobin dissociation curve is a graph that describes the relationship of partial pressure to the binding of oxygen to heme and its subsequent dissociation from heme ( Figure 22.26 ) . Remember that gases travel from an area of higher partial pressure to an area of lower partial pressure . In addition , the affinity of an oxygen molecule for heme increases as more oxygen molecules are bound . <hl> Therefore , in the oxygen – hemoglobin saturation curve , as the partial pressure of oxygen increases , a proportionately greater number of oxygen molecules are bound by heme . <hl> Not surprisingly , the oxygen – hemoglobin saturation / dissociation curve also shows that the lower the partial pressure of oxygen , the fewer oxygen molecules are bound to heme . As a result , the partial pressure of oxygen plays a major role in determining the degree of binding of oxygen to heme at the site of the respiratory membrane , as well as the degree of dissociation of oxygen from heme at the site of body tissues .", "hl_sentences": "The pH of the blood is another factor that influences the oxygen – hemoglobin saturation / dissociation curve ( see Figure 22.26 ) . Factors other than partial pressure also affect the oxygen – hemoglobin saturation / dissociation curve . For example , a higher temperature promotes hemoglobin and oxygen to dissociate faster , whereas a lower temperature inhibits dissociation ( see Figure 22.26 , middle ) . Certain hormones , such as androgens , epinephrine , thyroid hormones , and growth hormone , can affect the oxygen – hemoglobin saturation / disassociation curve by stimulating the production of a compound called 2,3- bisphosphoglycerate ( BPG ) by erythrocytes . Therefore , in the oxygen – hemoglobin saturation curve , as the partial pressure of oxygen increases , a proportionately greater number of oxygen molecules are bound by heme .", "question": { "cloze_format": "The ___ factor plays a role in the oxygen–hemoglobin saturation/dissociation curve.", "normal_format": "Which of the following factors play a role in the oxygen–hemoglobin saturation/dissociation curve?", "question_choices": [ "temperature", "pH", "BPG", "all of the above" ], "question_id": "fs-id2072180", "question_text": "Which of the following factors play a role in the oxygen–hemoglobin saturation/dissociation curve?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 1, "ans_text": "Chloride is exchanged for bicarbonate." }, "bloom": "1", "hl_context": "Bicarbonate tends to build up in the erythrocytes , so that there is a greater concentration of bicarbonate in the erythrocytes than in the surrounding blood plasma . <hl> As a result , some of the bicarbonate will leave the erythrocytes and move down its concentration gradient into the plasma in exchange for chloride ( Cl – ) ions . <hl> <hl> This phenomenon is referred to as the chloride shift and occurs because by exchanging one negative ion for another negative ion , neither the electrical charge of the erythrocytes nor that of the blood is altered . <hl>", "hl_sentences": "As a result , some of the bicarbonate will leave the erythrocytes and move down its concentration gradient into the plasma in exchange for chloride ( Cl – ) ions . This phenomenon is referred to as the chloride shift and occurs because by exchanging one negative ion for another negative ion , neither the electrical charge of the erythrocytes nor that of the blood is altered .", "question": { "cloze_format": "___ occurs during the chloride shift.", "normal_format": "Which of the following occurs during the chloride shift?", "question_choices": [ "Chloride is removed from the erythrocyte.", "Chloride is exchanged for bicarbonate.", "Bicarbonate is removed from the erythrocyte.", "Bicarbonate is removed from the blood." ], "question_id": "fs-id1525443", "question_text": "Which of the following occurs during the chloride shift?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 0, "ans_text": "Haldane effect" }, "bloom": null, "hl_context": "In addition to the partial pressure of carbon dioxide , the oxygen saturation of hemoglobin and the partial pressure of oxygen in the blood also influence the affinity of hemoglobin for carbon dioxide . <hl> The Haldane effect is a phenomenon that arises from the relationship between the partial pressure of oxygen and the affinity of hemoglobin for carbon dioxide . <hl> Hemoglobin that is saturated with oxygen does not readily bind carbon dioxide . However , when oxygen is not bound to heme and the partial pressure of oxygen is low , hemoglobin readily binds to carbon dioxide .", "hl_sentences": "The Haldane effect is a phenomenon that arises from the relationship between the partial pressure of oxygen and the affinity of hemoglobin for carbon dioxide .", "question": { "cloze_format": "A low partial pressure of oxygen promotes hemoglobin binding to carbon dioxide. This is an example of the ________.", "normal_format": "A low partial pressure of oxygen promotes hemoglobin binding to carbon dioxide. What is this an example of?", "question_choices": [ "Haldane effect", "Bohr effect", "Dalton’s law", "Henry’s law" ], "question_id": "fs-id1493008", "question_text": "A low partial pressure of oxygen promotes hemoglobin binding to carbon dioxide. This is an example of the ________." }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 0, "ans_text": "hyperventilation" }, "bloom": "1", "hl_context": "Hyperpnea is an increased depth and rate of ventilation to meet an increase in oxygen demand as might be seen in exercise or disease , particularly diseases that target the respiratory or digestive tracts . This does not significantly alter blood oxygen or carbon dioxide levels , but merely increases the depth and rate of ventilation to meet the demand of the cells . <hl> In contrast , hyperventilation is an increased ventilation rate that is independent of the cellular oxygen needs and leads to abnormally low blood carbon dioxide levels and high ( alkaline ) blood pH . <hl>", "hl_sentences": "In contrast , hyperventilation is an increased ventilation rate that is independent of the cellular oxygen needs and leads to abnormally low blood carbon dioxide levels and high ( alkaline ) blood pH .", "question": { "cloze_format": "Increased ventilation that results in an increase in blood pH is called ________.", "normal_format": "What is increased ventilation that results in an increase in blood pH called?", "question_choices": [ "hyperventilation", "hyperpnea", "acclimatization", "apnea" ], "question_id": "fs-id2772648", "question_text": "Increased ventilation that results in an increase in blood pH is called ________." }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 3, "ans_text": "small venous reserve of oxygen" }, "bloom": null, "hl_context": "<hl> Acute mountain sickness ( AMS ) , or altitude sickness , is a condition that results from acute exposure to high altitudes due to a low partial pressure of oxygen at high altitudes . <hl> AMS typically can occur at 2400 meters (8 000 feet ) above sea level . <hl> AMS is a result of low blood oxygen levels , as the body has acute difficulty adjusting to the low partial pressure of oxygen . <hl> In serious cases , AMS can cause pulmonary or cerebral edema . Symptoms of AMS include nausea , vomiting , fatigue , lightheadedness , drowsiness , feeling disoriented , increased pulse , and nosebleeds . The only treatment for AMS is descending to a lower altitude ; however , pharmacologic treatments and supplemental oxygen can improve symptoms . AMS can be prevented by slowly ascending to the desired altitude , allowing the body to acclimate , as well as maintaining proper hydration .", "hl_sentences": "Acute mountain sickness ( AMS ) , or altitude sickness , is a condition that results from acute exposure to high altitudes due to a low partial pressure of oxygen at high altitudes . AMS is a result of low blood oxygen levels , as the body has acute difficulty adjusting to the low partial pressure of oxygen .", "question": { "cloze_format": "Exercise can trigger symptoms of AMS due to ___ .", "normal_format": "Exercise can trigger symptoms of AMS due to which of the following?", "question_choices": [ "low partial pressure of oxygen", "low atmospheric pressure", "abnormal neural signals", "small venous reserve of oxygen" ], "question_id": "fs-id2180766", "question_text": "Exercise can trigger symptoms of AMS due to which of the following?" }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 3, "ans_text": "erythropoietin" }, "bloom": null, "hl_context": "Especially in situations where the ascent occurs too quickly , traveling to areas of high altitude can cause AMS . Acclimatization is the process of adjustment that the respiratory system makes due to chronic exposure to a high altitude . Over a period of time , the body adjusts to accommodate the lower partial pressure of oxygen . The low partial pressure of oxygen at high altitudes results in a lower oxygen saturation level of hemoglobin in the blood . In turn , the tissue levels of oxygen are also lower . <hl> As a result , the kidneys are stimulated to produce the hormone erythropoietin ( EPO ) , which stimulates the production of erythrocytes , resulting in a greater number of circulating erythrocytes in an individual at a high altitude over a long period . <hl> With more red blood cells , there is more hemoglobin to help transport the available oxygen . Even though there is low saturation of each hemoglobin molecule , there will be more hemoglobin present , and therefore more oxygen in the blood . Over time , this allows the person to partake in physical exertion without developing AMS . 22.7 Embryonic Development of the Respiratory System Learning Objectives By the end of this section , you will be able to :", "hl_sentences": "As a result , the kidneys are stimulated to produce the hormone erythropoietin ( EPO ) , which stimulates the production of erythrocytes , resulting in a greater number of circulating erythrocytes in an individual at a high altitude over a long period .", "question": { "cloze_format": "___ stimulates the production of erythrocytes.", "normal_format": "Which of the following stimulates the production of erythrocytes?", "question_choices": [ "AMS", "high blood levels of carbon dioxide", "low atmospheric pressure", "erythropoietin" ], "question_id": "fs-id1959452", "question_text": "Which of the following stimulates the production of erythrocytes?" }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 2, "ans_text": "ectoderm" }, "bloom": null, "hl_context": "Respiratory development in the embryo begins around week 4 . <hl> Ectodermal tissue from the anterior head region invaginates posteriorly to form olfactory pits , which fuse with endodermal tissue of the developing pharynx . <hl> An olfactory pit is one of a pair of structures that will enlarge to become the nasal cavity . At about this same time , the lung bud forms . The lung bud is a dome-shaped structure composed of tissue that bulges from the foregut . The foregut is endoderm just inferior to the pharyngeal pouches . The laryngotracheal bud is a structure that forms from the longitudinal extension of the lung bud as development progresses . The portion of this structure nearest the pharynx becomes the trachea , whereas the distal end becomes more bulbous , forming bronchial buds . A bronchial bud is one of a pair of structures that will eventually become the bronchi and all other lower respiratory structures ( Figure 22.29 ) .", "hl_sentences": "Ectodermal tissue from the anterior head region invaginates posteriorly to form olfactory pits , which fuse with endodermal tissue of the developing pharynx .", "question": { "cloze_format": "The olfactory pits form from ___ .", "normal_format": "The olfactory pits form from which of the following?", "question_choices": [ "mesoderm", "cartilage", "ectoderm", "endoderm" ], "question_id": "fs-id13721390", "question_text": "The olfactory pits form from which of the following?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 0, "ans_text": "early childhood, around 8 years of age" }, "bloom": null, "hl_context": "Major growth and maturation of the respiratory system occurs from week 24 until term . More alveolar precursors develop , and larger amounts of pulmonary surfactant are produced . Surfactant levels are not generally adequate to create effective lung compliance until about the eighth month of pregnancy . The respiratory system continues to expand , and the surfaces that will form the respiratory membrane develop further . At this point , pulmonary capillaries have formed and continue to expand , creating a large surface area for gas exchange . The major milestone of respiratory development occurs at around week 28 , when sufficient alveolar precursors have matured so that a baby born prematurely at this time can usually breathe on its own . <hl> However , alveoli continue to develop and mature into childhood . <hl> <hl> A full complement of functional alveoli does not appear until around 8 years of age . <hl> The development of the respiratory system begins at about week 4 of gestation . By week 28 , enough alveoli have matured that a baby born prematurely at this time can usually breathe on its own . <hl> The respiratory system , however , is not fully developed until early childhood , when a full complement of mature alveoli is present . <hl>", "hl_sentences": "However , alveoli continue to develop and mature into childhood . A full complement of functional alveoli does not appear until around 8 years of age . The respiratory system , however , is not fully developed until early childhood , when a full complement of mature alveoli is present .", "question": { "cloze_format": "A full complement of mature alveoli are present by ________.", "normal_format": "A full complement of mature alveoli are present by what?", "question_choices": [ "early childhood, around 8 years of age", "birth", "37 weeks", "16 weeks" ], "question_id": "fs-id2069835", "question_text": "A full complement of mature alveoli are present by ________." }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 1, "ans_text": "difficulty inflating the lungs" }, "bloom": null, "hl_context": "<hl> Respiratory distress syndrome ( RDS ) primarily occurs in infants born prematurely . <hl> Up to 50 percent of infants born between 26 and 28 weeks and fewer than 30 percent of infants born between 30 and 31 weeks develop RDS . <hl> RDS results from insufficient production of pulmonary surfactant , thereby preventing the lungs from properly inflating at birth . <hl> A small amount of pulmonary surfactant is produced beginning at around 20 weeks ; however , this is not sufficient for inflation of the lungs . As a result , dyspnea occurs and gas exchange cannot be performed properly . Blood oxygen levels are low , whereas blood carbon dioxide levels and pH are high .", "hl_sentences": "Respiratory distress syndrome ( RDS ) primarily occurs in infants born prematurely . RDS results from insufficient production of pulmonary surfactant , thereby preventing the lungs from properly inflating at birth .", "question": { "cloze_format": "If a baby is born prematurely before type II cells produce sufficient pulmonary surfactant, you might expect ___ .", "normal_format": "If a baby is born prematurely before type II cells produce sufficient pulmonary surfactant, which of the following might you expect?", "question_choices": [ "difficulty expressing fluid", "difficulty inflating the lungs", "difficulty with pulmonary capillary flow", "no difficulty as type I cells can provide enough surfactant for normal breathing" ], "question_id": "fs-id2288656", "question_text": "If a baby is born prematurely before type II cells produce sufficient pulmonary surfactant, which of the following might you expect?" }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 0, "ans_text": "around week 20" }, "bloom": null, "hl_context": "<hl> Although the function of fetal breathing movements is not entirely clear , they can be observed starting at 20 – 21 weeks of development . <hl> Fetal breathing movements involve muscle contractions that cause the inhalation of amniotic fluid and exhalation of the same fluid , with pulmonary surfactant and mucus . Fetal breathing movements are not continuous and may include periods of frequent movements and periods of no movements . Maternal factors can influence the frequency of breathing movements . For example , high blood glucose levels , called hyperglycemia , can boost the number of breathing movements . Conversely , low blood glucose levels , called hypoglycemia , can reduce the number of fetal breathing movements . Tobacco use is also known to lower fetal breathing rates . Fetal breathing may help tone the muscles in preparation for breathing movements once the fetus is born . It may also help the alveoli to form and mature . Fetal breathing movements are considered a sign of robust health . Once the respiratory bronchioles form , further development includes extensive vascularization , or the development of the blood vessels , as well as the formation of alveolar ducts and alveolar precursors . At about week 19 , the respiratory bronchioles have formed . In addition , cells lining the respiratory structures begin to differentiate to form type I and type II pneumocytes . Once type II cells have differentiated , they begin to secrete small amounts of pulmonary surfactant . <hl> Around week 20 , fetal breathing movements may begin . <hl>", "hl_sentences": "Although the function of fetal breathing movements is not entirely clear , they can be observed starting at 20 – 21 weeks of development . Around week 20 , fetal breathing movements may begin .", "question": { "cloze_format": "Fetal breathing movements begin ___ .", "normal_format": "When do fetal breathing movements begin?", "question_choices": [ "around week 20", "around week 37", "around week 16", "after birth" ], "question_id": "fs-id2019566", "question_text": "When do fetal breathing movements begin?" }, "references_are_paraphrase": null } ]
22
22.1 Organs and Structures of the Respiratory System Learning Objectives By the end of this section, you will be able to: List the structures that make up the respiratory system Describe how the respiratory system processes oxygen and CO 2 Compare and contrast the functions of upper respiratory tract with the lower respiratory tract The major organs of the respiratory system function primarily to provide oxygen to body tissues for cellular respiration, remove the waste product carbon dioxide, and help to maintain acid-base balance. Portions of the respiratory system are also used for non-vital functions, such as sensing odors, speech production, and for straining, such as during childbirth or coughing ( Figure 22.2 ). Functionally, the respiratory system can be divided into a conducting zone and a respiratory zone. The conducting zone of the respiratory system includes the organs and structures not directly involved in gas exchange. The gas exchange occurs in the respiratory zone . Conducting Zone The major functions of the conducting zone are to provide a route for incoming and outgoing air, remove debris and pathogens from the incoming air, and warm and humidify the incoming air. Several structures within the conducting zone perform other functions as well. The epithelium of the nasal passages, for example, is essential to sensing odors, and the bronchial epithelium that lines the lungs can metabolize some airborne carcinogens. The Nose and its Adjacent Structures The major entrance and exit for the respiratory system is through the nose. When discussing the nose, it is helpful to divide it into two major sections: the external nose, and the nasal cavity or internal nose. The external nose consists of the surface and skeletal structures that result in the outward appearance of the nose and contribute to its numerous functions ( Figure 22.3 ). The root is the region of the nose located between the eyebrows. The bridge is the part of the nose that connects the root to the rest of the nose. The dorsum nasi is the length of the nose. The apex is the tip of the nose. On either side of the apex, the nostrils are formed by the alae (singular = ala). An ala is a cartilaginous structure that forms the lateral side of each naris (plural = nares), or nostril opening. The philtrum is the concave surface that connects the apex of the nose to the upper lip. Underneath the thin skin of the nose are its skeletal features (see Figure 22.3 , lower illustration). While the root and bridge of the nose consist of bone, the protruding portion of the nose is composed of cartilage. As a result, when looking at a skull, the nose is missing. The nasal bone is one of a pair of bones that lies under the root and bridge of the nose. The nasal bone articulates superiorly with the frontal bone and laterally with the maxillary bones. Septal cartilage is flexible hyaline cartilage connected to the nasal bone, forming the dorsum nasi. The alar cartilage consists of the apex of the nose; it surrounds the naris. The nares open into the nasal cavity, which is separated into left and right sections by the nasal septum ( Figure 22.4 ). The nasal septum is formed anteriorly by a portion of the septal cartilage (the flexible portion you can touch with your fingers) and posteriorly by the perpendicular plate of the ethmoid bone (a cranial bone located just posterior to the nasal bones) and the thin vomer bones (whose name refers to its plough shape). Each lateral wall of the nasal cavity has three bony projections, called the superior, middle, and inferior nasal conchae. The inferior conchae are separate bones, whereas the superior and middle conchae are portions of the ethmoid bone. Conchae serve to increase the surface area of the nasal cavity and to disrupt the flow of air as it enters the nose, causing air to bounce along the epithelium, where it is cleaned and warmed. The conchae and meatuses also conserve water and prevent dehydration of the nasal epithelium by trapping water during exhalation. The floor of the nasal cavity is composed of the palate. The hard palate at the anterior region of the nasal cavity is composed of bone. The soft palate at the posterior portion of the nasal cavity consists of muscle tissue. Air exits the nasal cavities via the internal nares and moves into the pharynx. Several bones that help form the walls of the nasal cavity have air-containing spaces called the paranasal sinuses, which serve to warm and humidify incoming air. Sinuses are lined with a mucosa. Each paranasal sinus is named for its associated bone: frontal sinus, maxillary sinus, sphenoidal sinus, and ethmoidal sinus. The sinuses produce mucus and lighten the weight of the skull. The nares and anterior portion of the nasal cavities are lined with mucous membranes, containing sebaceous glands and hair follicles that serve to prevent the passage of large debris, such as dirt, through the nasal cavity. An olfactory epithelium used to detect odors is found deeper in the nasal cavity. The conchae, meatuses, and paranasal sinuses are lined by respiratory epithelium composed of pseudostratified ciliated columnar epithelium ( Figure 22.5 ). The epithelium contains goblet cells, one of the specialized, columnar epithelial cells that produce mucus to trap debris. The cilia of the respiratory epithelium help remove the mucus and debris from the nasal cavity with a constant beating motion, sweeping materials towards the throat to be swallowed. Interestingly, cold air slows the movement of the cilia, resulting in accumulation of mucus that may in turn lead to a runny nose during cold weather. This moist epithelium functions to warm and humidify incoming air. Capillaries located just beneath the nasal epithelium warm the air by convection. Serous and mucus-producing cells also secrete the lysozyme enzyme and proteins called defensins, which have antibacterial properties. Immune cells that patrol the connective tissue deep to the respiratory epithelium provide additional protection. Interactive Link View the University of Michigan WebScope to explore the tissue sample in greater detail. Pharynx The pharynx is a tube formed by skeletal muscle and lined by mucous membrane that is continuous with that of the nasal cavities (see Figure 22.4 ). The pharynx is divided into three major regions: the nasopharynx, the oropharynx, and the laryngopharynx ( Figure 22.6 ). The nasopharynx is flanked by the conchae of the nasal cavity, and it serves only as an airway. At the top of the nasopharynx are the pharyngeal tonsils. A pharyngeal tonsil , also called an adenoid, is an aggregate of lymphoid reticular tissue similar to a lymph node that lies at the superior portion of the nasopharynx. The function of the pharyngeal tonsil is not well understood, but it contains a rich supply of lymphocytes and is covered with ciliated epithelium that traps and destroys invading pathogens that enter during inhalation. The pharyngeal tonsils are large in children, but interestingly, tend to regress with age and may even disappear. The uvula is a small bulbous, teardrop-shaped structure located at the apex of the soft palate. Both the uvula and soft palate move like a pendulum during swallowing, swinging upward to close off the nasopharynx to prevent ingested materials from entering the nasal cavity. In addition, auditory (Eustachian) tubes that connect to each middle ear cavity open into the nasopharynx. This connection is why colds often lead to ear infections. The oropharynx is a passageway for both air and food. The oropharynx is bordered superiorly by the nasopharynx and anteriorly by the oral cavity. The fauces is the opening at the connection between the oral cavity and the oropharynx. As the nasopharynx becomes the oropharynx, the epithelium changes from pseudostratified ciliated columnar epithelium to stratified squamous epithelium. The oropharynx contains two distinct sets of tonsils, the palatine and lingual tonsils. A palatine tonsil is one of a pair of structures located laterally in the oropharynx in the area of the fauces. The lingual tonsil is located at the base of the tongue. Similar to the pharyngeal tonsil, the palatine and lingual tonsils are composed of lymphoid tissue, and trap and destroy pathogens entering the body through the oral or nasal cavities. The laryngopharynx is inferior to the oropharynx and posterior to the larynx. It continues the route for ingested material and air until its inferior end, where the digestive and respiratory systems diverge. The stratified squamous epithelium of the oropharynx is continuous with the laryngopharynx. Anteriorly, the laryngopharynx opens into the larynx, whereas posteriorly, it enters the esophagus. Larynx The larynx is a cartilaginous structure inferior to the laryngopharynx that connects the pharynx to the trachea and helps regulate the volume of air that enters and leaves the lungs ( Figure 22.7 ). The structure of the larynx is formed by several pieces of cartilage. Three large cartilage pieces—the thyroid cartilage (anterior), epiglottis (superior), and cricoid cartilage (inferior)—form the major structure of the larynx. The thyroid cartilage is the largest piece of cartilage that makes up the larynx. The thyroid cartilage consists of the laryngeal prominence , or “Adam’s apple,” which tends to be more prominent in males. The thick cricoid cartilage forms a ring, with a wide posterior region and a thinner anterior region. Three smaller, paired cartilages—the arytenoids, corniculates, and cuneiforms—attach to the epiglottis and the vocal cords and muscle that help move the vocal cords to produce speech. The epiglottis , attached to the thyroid cartilage, is a very flexible piece of elastic cartilage that covers the opening of the trachea (see Figure 22.4 ). When in the “closed” position, the unattached end of the epiglottis rests on the glottis. The glottis is composed of the vestibular folds, the true vocal cords, and the space between these folds ( Figure 22.8 ). A vestibular fold , or false vocal cord, is one of a pair of folded sections of mucous membrane. A true vocal cord is one of the white, membranous folds attached by muscle to the thyroid and arytenoid cartilages of the larynx on their outer edges. The inner edges of the true vocal cords are free, allowing oscillation to produce sound. The size of the membranous folds of the true vocal cords differs between individuals, producing voices with different pitch ranges. Folds in males tend to be larger than those in females, which create a deeper voice. The act of swallowing causes the pharynx and larynx to lift upward, allowing the pharynx to expand and the epiglottis of the larynx to swing downward, closing the opening to the trachea. These movements produce a larger area for food to pass through, while preventing food and beverages from entering the trachea. Continuous with the laryngopharynx, the superior portion of the larynx is lined with stratified squamous epithelium, transitioning into pseudostratified ciliated columnar epithelium that contains goblet cells. Similar to the nasal cavity and nasopharynx, this specialized epithelium produces mucus to trap debris and pathogens as they enter the trachea. The cilia beat the mucus upward towards the laryngopharynx, where it can be swallowed down the esophagus. Trachea The trachea (windpipe) extends from the larynx toward the lungs ( Figure 22.9 a ). The trachea is formed by 16 to 20 stacked, C-shaped pieces of hyaline cartilage that are connected by dense connective tissue. The trachealis muscle and elastic connective tissue together form the fibroelastic membrane , a flexible membrane that closes the posterior surface of the trachea, connecting the C-shaped cartilages. The fibroelastic membrane allows the trachea to stretch and expand slightly during inhalation and exhalation, whereas the rings of cartilage provide structural support and prevent the trachea from collapsing. In addition, the trachealis muscle can be contracted to force air through the trachea during exhalation. The trachea is lined with pseudostratified ciliated columnar epithelium, which is continuous with the larynx. The esophagus borders the trachea posteriorly. Bronchial Tree The trachea branches into the right and left primary bronchi at the carina. These bronchi are also lined by pseudostratified ciliated columnar epithelium containing mucus-producing goblet cells ( Figure 22.9 b ). The carina is a raised structure that contains specialized nervous tissue that induces violent coughing if a foreign body, such as food, is present. Rings of cartilage, similar to those of the trachea, support the structure of the bronchi and prevent their collapse. The primary bronchi enter the lungs at the hilum, a concave region where blood vessels, lymphatic vessels, and nerves also enter the lungs. The bronchi continue to branch into bronchial a tree. A bronchial tree (or respiratory tree) is the collective term used for these multiple-branched bronchi. The main function of the bronchi, like other conducting zone structures, is to provide a passageway for air to move into and out of each lung. In addition, the mucous membrane traps debris and pathogens. A bronchiole branches from the tertiary bronchi. Bronchioles, which are about 1 mm in diameter, further branch until they become the tiny terminal bronchioles, which lead to the structures of gas exchange. There are more than 1000 terminal bronchioles in each lung. The muscular walls of the bronchioles do not contain cartilage like those of the bronchi. This muscular wall can change the size of the tubing to increase or decrease airflow through the tube. Respiratory Zone In contrast to the conducting zone, the respiratory zone includes structures that are directly involved in gas exchange. The respiratory zone begins where the terminal bronchioles join a respiratory bronchiole , the smallest type of bronchiole ( Figure 22.10 ), which then leads to an alveolar duct, opening into a cluster of alveoli. Alveoli An alveolar duct is a tube composed of smooth muscle and connective tissue, which opens into a cluster of alveoli. An alveolus is one of the many small, grape-like sacs that are attached to the alveolar ducts. An alveolar sac is a cluster of many individual alveoli that are responsible for gas exchange. An alveolus is approximately 200 μm in diameter with elastic walls that allow the alveolus to stretch during air intake, which greatly increases the surface area available for gas exchange. Alveoli are connected to their neighbors by alveolar pores , which help maintain equal air pressure throughout the alveoli and lung ( Figure 22.11 ). The alveolar wall consists of three major cell types: type I alveolar cells, type II alveolar cells, and alveolar macrophages. A type I alveolar cell is a squamous epithelial cell of the alveoli, which constitute up to 97 percent of the alveolar surface area. These cells are about 25 nm thick and are highly permeable to gases. A type II alveolar cell is interspersed among the type I cells and secretes pulmonary surfactant , a substance composed of phospholipids and proteins that reduces the surface tension of the alveoli. Roaming around the alveolar wall is the alveolar macrophage , a phagocytic cell of the immune system that removes debris and pathogens that have reached the alveoli. The simple squamous epithelium formed by type I alveolar cells is attached to a thin, elastic basement membrane. This epithelium is extremely thin and borders the endothelial membrane of capillaries. Taken together, the alveoli and capillary membranes form a respiratory membrane that is approximately 0.5 μm (micrometers) thick. The respiratory membrane allows gases to cross by simple diffusion, allowing oxygen to be picked up by the blood for transport and CO 2 to be released into the air of the alveoli. Diseases of the... Respiratory System: Asthma Asthma is common condition that affects the lungs in both adults and children. Approximately 8.2 percent of adults (18.7 million) and 9.4 percent of children (7 million) in the United States suffer from asthma. In addition, asthma is the most frequent cause of hospitalization in children. Asthma is a chronic disease characterized by inflammation and edema of the airway, and bronchospasms (that is, constriction of the bronchioles), which can inhibit air from entering the lungs. In addition, excessive mucus secretion can occur, which further contributes to airway occlusion ( Figure 22.12 ). Cells of the immune system, such as eosinophils and mononuclear cells, may also be involved in infiltrating the walls of the bronchi and bronchioles. Bronchospasms occur periodically and lead to an “asthma attack.” An attack may be triggered by environmental factors such as dust, pollen, pet hair, or dander, changes in the weather, mold, tobacco smoke, and respiratory infections, or by exercise and stress. Symptoms of an asthma attack involve coughing, shortness of breath, wheezing, and tightness of the chest. Symptoms of a severe asthma attack that requires immediate medical attention would include difficulty breathing that results in blue (cyanotic) lips or face, confusion, drowsiness, a rapid pulse, sweating, and severe anxiety. The severity of the condition, frequency of attacks, and identified triggers influence the type of medication that an individual may require. Longer-term treatments are used for those with more severe asthma. Short-term, fast-acting drugs that are used to treat an asthma attack are typically administered via an inhaler. For young children or individuals who have difficulty using an inhaler, asthma medications can be administered via a nebulizer. In many cases, the underlying cause of the condition is unknown. However, recent research has demonstrated that certain viruses, such as human rhinovirus C (HRVC), and the bacteria Mycoplasma pneumoniae and Chlamydia pneumoniae that are contracted in infancy or early childhood, may contribute to the development of many cases of asthma. Interactive Link Visit this site to learn more about what happens during an asthma attack. What are the three changes that occur inside the airways during an asthma attack? 22.2 The Lungs Learning Objectives By the end of this section, you will be able to: Describe the overall function of the lung Summarize the blood flow pattern associated with the lungs Outline the anatomy of the blood supply to the lungs Describe the pleura of the lungs and their function A major organ of the respiratory system, each lung houses structures of both the conducting and respiratory zones. The main function of the lungs is to perform the exchange of oxygen and carbon dioxide with air from the atmosphere. To this end, the lungs exchange respiratory gases across a very large epithelial surface area—about 70 square meters—that is highly permeable to gases. Gross Anatomy of the Lungs The lungs are pyramid-shaped, paired organs that are connected to the trachea by the right and left bronchi; on the inferior surface, the lungs are bordered by the diaphragm. The diaphragm is a dome-shaped muscle located at the base of the lungs and thoracic cavity. The lungs are enclosed by the pleurae, which are attached to the mediastinum. The right lung is shorter and wider than the left lung, and the left lung occupies a smaller volume than the right. The cardiac notch is an indentation on the surface of the left lung, and it allows space for the heart ( Figure 22.13 ). The apex of the lung is the superior region, whereas the base is the opposite region near the diaphragm. The costal surface of the lung borders the ribs. The mediastinal surface faces the midline. Each lung is composed of smaller units called lobes. Fissures separate these lobes from each other. The right lung consists of three lobes: the superior, middle, and inferior lobes. The left lung consists of two lobes: the superior and inferior lobes. A bronchopulmonary segment is a division of a lobe, and each lobe houses multiple bronchopulmonary segments. Each segment receives air from its own tertiary bronchus and is supplied with blood by its own artery. Some diseases of the lungs typically affect one or more bronchopulmonary segments, and in some cases, the diseased segments can be surgically removed with little influence on neighboring segments. A pulmonary lobule is a subdivision formed as the bronchi branch into bronchioles. Each lobule receives its own large bronchiole that has multiple branches. An interlobular septum is a wall, composed of connective tissue, which separates lobules from one another. Blood Supply and Nervous Innervation of the Lungs The blood supply of the lungs plays an important role in gas exchange and serves as a transport system for gases throughout the body. In addition, innervation by the both the parasympathetic and sympathetic nervous systems provides an important level of control through dilation and constriction of the airway. Blood Supply The major function of the lungs is to perform gas exchange, which requires blood from the pulmonary circulation. This blood supply contains deoxygenated blood and travels to the lungs where erythrocytes, also known as red blood cells, pick up oxygen to be transported to tissues throughout the body. The pulmonary artery is an artery that arises from the pulmonary trunk and carries deoxygenated, arterial blood to the alveoli. The pulmonary artery branches multiple times as it follows the bronchi, and each branch becomes progressively smaller in diameter. One arteriole and an accompanying venule supply and drain one pulmonary lobule. As they near the alveoli, the pulmonary arteries become the pulmonary capillary network. The pulmonary capillary network consists of tiny vessels with very thin walls that lack smooth muscle fibers. The capillaries branch and follow the bronchioles and structure of the alveoli. It is at this point that the capillary wall meets the alveolar wall, creating the respiratory membrane. Once the blood is oxygenated, it drains from the alveoli by way of multiple pulmonary veins, which exit the lungs through the hilum . Nervous Innervation Dilation and constriction of the airway are achieved through nervous control by the parasympathetic and sympathetic nervous systems. The parasympathetic system causes bronchoconstriction , whereas the sympathetic nervous system stimulates bronchodilation . Reflexes such as coughing, and the ability of the lungs to regulate oxygen and carbon dioxide levels, also result from this autonomic nervous system control. Sensory nerve fibers arise from the vagus nerve, and from the second to fifth thoracic ganglia. The pulmonary plexus is a region on the lung root formed by the entrance of the nerves at the hilum. The nerves then follow the bronchi in the lungs and branch to innervate muscle fibers, glands, and blood vessels. Pleura of the Lungs Each lung is enclosed within a cavity that is surrounded by the pleura. The pleura (plural = pleurae) is a serous membrane that surrounds the lung. The right and left pleurae, which enclose the right and left lungs, respectively, are separated by the mediastinum. The pleurae consist of two layers. The visceral pleura is the layer that is superficial to the lungs, and extends into and lines the lung fissures ( Figure 22.14 ). In contrast, the parietal pleura is the outer layer that connects to the thoracic wall, the mediastinum, and the diaphragm. The visceral and parietal pleurae connect to each other at the hilum. The pleural cavity is the space between the visceral and parietal layers. The pleurae perform two major functions: They produce pleural fluid and create cavities that separate the major organs. Pleural fluid is secreted by mesothelial cells from both pleural layers and acts to lubricate their surfaces. This lubrication reduces friction between the two layers to prevent trauma during breathing, and creates surface tension that helps maintain the position of the lungs against the thoracic wall. This adhesive characteristic of the pleural fluid causes the lungs to enlarge when the thoracic wall expands during ventilation, allowing the lungs to fill with air. The pleurae also create a division between major organs that prevents interference due to the movement of the organs, while preventing the spread of infection. Everyday Connection The Effects of Second-Hand Tobacco Smoke The burning of a tobacco cigarette creates multiple chemical compounds that are released through mainstream smoke, which is inhaled by the smoker, and through sidestream smoke, which is the smoke that is given off by the burning cigarette. Second-hand smoke, which is a combination of sidestream smoke and the mainstream smoke that is exhaled by the smoker, has been demonstrated by numerous scientific studies to cause disease. At least 40 chemicals in sidestream smoke have been identified that negatively impact human health, leading to the development of cancer or other conditions, such as immune system dysfunction, liver toxicity, cardiac arrhythmias, pulmonary edema, and neurological dysfunction. Furthermore, second-hand smoke has been found to harbor at least 250 compounds that are known to be toxic, carcinogenic, or both. Some major classes of carcinogens in second-hand smoke are polyaromatic hydrocarbons (PAHs), N-nitrosamines, aromatic amines, formaldehyde, and acetaldehyde. Tobacco and second-hand smoke are considered to be carcinogenic. Exposure to second-hand smoke can cause lung cancer in individuals who are not tobacco users themselves. It is estimated that the risk of developing lung cancer is increased by up to 30 percent in nonsmokers who live with an individual who smokes in the house, as compared to nonsmokers who are not regularly exposed to second-hand smoke. Children are especially affected by second-hand smoke. Children who live with an individual who smokes inside the home have a larger number of lower respiratory infections, which are associated with hospitalizations, and higher risk of sudden infant death syndrome (SIDS). Second-hand smoke in the home has also been linked to a greater number of ear infections in children, as well as worsening symptoms of asthma. 22.3 The Process of Breathing Learning Objectives By the end of this section, you will be able to: Describe the mechanisms that drive breathing Discuss how pressure, volume, and resistance are related List the steps involved in pulmonary ventilation Discuss the physical factors related to breathing Discuss the meaning of respiratory volume and capacities Define respiratory rate Outline the mechanisms behind the control of breathing Describe the respiratory centers of the medulla oblongata Describe the respiratory centers of the pons Discuss factors that can influence the respiratory rate Pulmonary ventilation is the act of breathing, which can be described as the movement of air into and out of the lungs. The major mechanisms that drive pulmonary ventilation are atmospheric pressure ( P atm ); the air pressure within the alveoli, called intra-alveolar pressure ( P alv ); and the pressure within the pleural cavity, called intrapleural pressure ( P ip ). Mechanisms of Breathing The intra-alveolar and intrapleural pressures are dependent on certain physical features of the lung. However, the ability to breathe—to have air enter the lungs during inspiration and air leave the lungs during expiration—is dependent on the air pressure of the atmosphere and the air pressure within the lungs. Pressure Relationships Inspiration (or inhalation) and expiration (or exhalation) are dependent on the differences in pressure between the atmosphere and the lungs. In a gas, pressure is a force created by the movement of gas molecules that are confined. For example, a certain number of gas molecules in a two-liter container has more room than the same number of gas molecules in a one-liter container ( Figure 22.15 ). In this case, the force exerted by the movement of the gas molecules against the walls of the two-liter container is lower than the force exerted by the gas molecules in the one-liter container. Therefore, the pressure is lower in the two-liter container and higher in the one-liter container. At a constant temperature, changing the volume occupied by the gas changes the pressure, as does changing the number of gas molecules. Boyle’s law describes the relationship between volume and pressure in a gas at a constant temperature. Boyle discovered that the pressure of a gas is inversely proportional to its volume: If volume increases, pressure decreases. Likewise, if volume decreases, pressure increases. Pressure and volume are inversely related ( P = k/ V ). Therefore, the pressure in the one-liter container (one-half the volume of the two-liter container) would be twice the pressure in the two-liter container. Boyle’s law is expressed by the following formula: P 1 V 1 = P 2 V 2 P 1 V 1 = P 2 V 2 In this formula, P 1 represents the initial pressure and V 1 represents the initial volume, whereas the final pressure and volume are represented by P 2 and V 2, respectively. If the two- and one-liter containers were connected by a tube and the volume of one of the containers were changed, then the gases would move from higher pressure (lower volume) to lower pressure (higher volume). Pulmonary ventilation is dependent on three types of pressure: atmospheric, intra-alveolar, and intrapleural. Atmospheric pressure is the amount of force that is exerted by gases in the air surrounding any given surface, such as the body. Atmospheric pressure can be expressed in terms of the unit atmosphere, abbreviated atm, or in millimeters of mercury (mm Hg). One atm is equal to 760 mm Hg, which is the atmospheric pressure at sea level. Typically, for respiration, other pressure values are discussed in relation to atmospheric pressure. Therefore, negative pressure is pressure lower than the atmospheric pressure, whereas positive pressure is pressure that it is greater than the atmospheric pressure. A pressure that is equal to the atmospheric pressure is expressed as zero. Intra-alveolar pressure (intrapulmonary pressure) is the pressure of the air within the alveoli, which changes during the different phases of breathing ( Figure 22.16 ). Because the alveoli are connected to the atmosphere via the tubing of the airways (similar to the two- and one-liter containers in the example above), the intrapulmonary pressure of the alveoli always equalizes with the atmospheric pressure. Intrapleural pressure is the pressure of the air within the pleural cavity, between the visceral and parietal pleurae. Similar to intra-alveolar pressure, intrapleural pressure also changes during the different phases of breathing. However, due to certain characteristics of the lungs, the intrapleural pressure is always lower than, or negative to, the intra-alveolar pressure (and therefore also to atmospheric pressure). Although it fluctuates during inspiration and expiration, intrapleural pressure remains approximately –4 mm Hg throughout the breathing cycle. Competing forces within the thorax cause the formation of the negative intrapleural pressure. One of these forces relates to the elasticity of the lungs themselves—elastic tissue pulls the lungs inward, away from the thoracic wall. Surface tension of alveolar fluid, which is mostly water, also creates an inward pull of the lung tissue. This inward tension from the lungs is countered by opposing forces from the pleural fluid and thoracic wall. Surface tension within the pleural cavity pulls the lungs outward. Too much or too little pleural fluid would hinder the creation of the negative intrapleural pressure; therefore, the level must be closely monitored by the mesothelial cells and drained by the lymphatic system. Since the parietal pleura is attached to the thoracic wall, the natural elasticity of the chest wall opposes the inward pull of the lungs. Ultimately, the outward pull is slightly greater than the inward pull, creating the –4 mm Hg intrapleural pressure relative to the intra-alveolar pressure. Transpulmonary pressure is the difference between the intrapleural and intra-alveolar pressures, and it determines the size of the lungs. A higher transpulmonary pressure corresponds to a larger lung. Physical Factors Affecting Ventilation In addition to the differences in pressures, breathing is also dependent upon the contraction and relaxation of muscle fibers of both the diaphragm and thorax. The lungs themselves are passive during breathing, meaning they are not involved in creating the movement that helps inspiration and expiration. This is because of the adhesive nature of the pleural fluid, which allows the lungs to be pulled outward when the thoracic wall moves during inspiration. The recoil of the thoracic wall during expiration causes compression of the lungs. Contraction and relaxation of the diaphragm and intercostals muscles (found between the ribs) cause most of the pressure changes that result in inspiration and expiration. These muscle movements and subsequent pressure changes cause air to either rush in or be forced out of the lungs. Other characteristics of the lungs influence the effort that must be expended to ventilate. Resistance is a force that slows motion, in this case, the flow of gases. The size of the airway is the primary factor affecting resistance. A small tubular diameter forces air through a smaller space, causing more collisions of air molecules with the walls of the airways. The following formula helps to describe the relationship between airway resistance and pressure changes: F = ∆ P / R F = ∆ P / R As noted earlier, there is surface tension within the alveoli caused by water present in the lining of the alveoli. This surface tension tends to inhibit expansion of the alveoli. However, pulmonary surfactant secreted by type II alveolar cells mixes with that water and helps reduce this surface tension. Without pulmonary surfactant, the alveoli would collapse during expiration. Thoracic wall compliance is the ability of the thoracic wall to stretch while under pressure. This can also affect the effort expended in the process of breathing. In order for inspiration to occur, the thoracic cavity must expand. The expansion of the thoracic cavity directly influences the capacity of the lungs to expand. If the tissues of the thoracic wall are not very compliant, it will be difficult to expand the thorax to increase the size of the lungs. Pulmonary Ventilation The difference in pressures drives pulmonary ventilation because air flows down a pressure gradient, that is, air flows from an area of higher pressure to an area of lower pressure. Air flows into the lungs largely due to a difference in pressure; atmospheric pressure is greater than intra-alveolar pressure, and intra-alveolar pressure is greater than intrapleural pressure. Air flows out of the lungs during expiration based on the same principle; pressure within the lungs becomes greater than the atmospheric pressure. Pulmonary ventilation comprises two major steps: inspiration and expiration. Inspiration is the process that causes air to enter the lungs, and expiration is the process that causes air to leave the lungs ( Figure 22.17 ). A respiratory cycle is one sequence of inspiration and expiration. In general, two muscle groups are used during normal inspiration: the diaphragm and the external intercostal muscles. Additional muscles can be used if a bigger breath is required. When the diaphragm contracts, it moves inferiorly toward the abdominal cavity, creating a larger thoracic cavity and more space for the lungs. Contraction of the external intercostal muscles moves the ribs upward and outward, causing the rib cage to expand, which increases the volume of the thoracic cavity. Due to the adhesive force of the pleural fluid, the expansion of the thoracic cavity forces the lungs to stretch and expand as well. This increase in volume leads to a decrease in intra-alveolar pressure, creating a pressure lower than atmospheric pressure. As a result, a pressure gradient is created that drives air into the lungs. The process of normal expiration is passive, meaning that energy is not required to push air out of the lungs. Instead, the elasticity of the lung tissue causes the lung to recoil, as the diaphragm and intercostal muscles relax following inspiration. In turn, the thoracic cavity and lungs decrease in volume, causing an increase in intrapulmonary pressure. The intrapulmonary pressure rises above atmospheric pressure, creating a pressure gradient that causes air to leave the lungs. There are different types, or modes, of breathing that require a slightly different process to allow inspiration and expiration. Quiet breathing , also known as eupnea, is a mode of breathing that occurs at rest and does not require the cognitive thought of the individual. During quiet breathing, the diaphragm and external intercostals must contract. A deep breath, called diaphragmatic breathing, requires the diaphragm to contract. As the diaphragm relaxes, air passively leaves the lungs. A shallow breath, called costal breathing, requires contraction of the intercostal muscles. As the intercostal muscles relax, air passively leaves the lungs. In contrast, forced breathing , also known as hyperpnea, is a mode of breathing that can occur during exercise or actions that require the active manipulation of breathing, such as singing. During forced breathing, inspiration and expiration both occur due to muscle contractions. In addition to the contraction of the diaphragm and intercostal muscles, other accessory muscles must also contract. During forced inspiration, muscles of the neck, including the scalenes, contract and lift the thoracic wall, increasing lung volume. During forced expiration, accessory muscles of the abdomen, including the obliques, contract, forcing abdominal organs upward against the diaphragm. This helps to push the diaphragm further into the thorax, pushing more air out. In addition, accessory muscles (primarily the internal intercostals) help to compress the rib cage, which also reduces the volume of the thoracic cavity. Respiratory Volumes and Capacities Respiratory volume is the term used for various volumes of air moved by or associated with the lungs at a given point in the respiratory cycle. There are four major types of respiratory volumes: tidal, residual, inspiratory reserve, and expiratory reserve ( Figure 22.18 ). Tidal volume (TV) is the amount of air that normally enters the lungs during quiet breathing, which is about 500 milliliters. Expiratory reserve volume (ERV) is the amount of air you can forcefully exhale past a normal tidal expiration, up to 1200 milliliters for men. Inspiratory reserve volume (IRV) is produced by a deep inhalation, past a tidal inspiration. This is the extra volume that can be brought into the lungs during a forced inspiration. Residual volume (RV) is the air left in the lungs if you exhale as much air as possible. The residual volume makes breathing easier by preventing the alveoli from collapsing. Respiratory volume is dependent on a variety of factors, and measuring the different types of respiratory volumes can provide important clues about a person’s respiratory health ( Figure 22.19 ). Respiratory capacity is the combination of two or more selected volumes, which further describes the amount of air in the lungs during a given time. For example, total lung capacity (TLC) is the sum of all of the lung volumes (TV, ERV, IRV, and RV), which represents the total amount of air a person can hold in the lungs after a forceful inhalation. TLC is about 6000 mL air for men, and about 4200 mL for women. Vital capacity (VC) is the amount of air a person can move into or out of his or her lungs, and is the sum of all of the volumes except residual volume (TV, ERV, and IRV), which is between 4000 and 5000 milliliters. Inspiratory capacity (IC) is the maximum amount of air that can be inhaled past a normal tidal expiration, is the sum of the tidal volume and inspiratory reserve volume. On the other hand, the functional residual capacity (FRC) is the amount of air that remains in the lung after a normal tidal expiration; it is the sum of expiratory reserve volume and residual volume (see Figure 22.18 ). Interactive Link Watch this video to learn more about lung volumes and spirometers. Explain how spirometry test results can be used to diagnose respiratory diseases or determine the effectiveness of disease treatment. In addition to the air that creates respiratory volumes, the respiratory system also contains anatomical dead space , which is air that is present in the airway that never reaches the alveoli and therefore never participates in gas exchange. Alveolar dead space involves air found within alveoli that are unable to function, such as those affected by disease or abnormal blood flow. Total dead space is the anatomical dead space and alveolar dead space together, and represents all of the air in the respiratory system that is not being used in the gas exchange process. Respiratory Rate and Control of Ventilation Breathing usually occurs without thought, although at times you can consciously control it, such as when you swim under water, sing a song, or blow bubbles. The respiratory rate is the total number of breaths, or respiratory cycles, that occur each minute. Respiratory rate can be an important indicator of disease, as the rate may increase or decrease during an illness or in a disease condition. The respiratory rate is controlled by the respiratory center located within the medulla oblongata in the brain, which responds primarily to changes in carbon dioxide, oxygen, and pH levels in the blood. The normal respiratory rate of a child decreases from birth to adolescence. A child under 1 year of age has a normal respiratory rate between 30 and 60 breaths per minute, but by the time a child is about 10 years old, the normal rate is closer to 18 to 30. By adolescence, the normal respiratory rate is similar to that of adults, 12 to 18 breaths per minute. Ventilation Control Centers The control of ventilation is a complex interplay of multiple regions in the brain that signal the muscles used in pulmonary ventilation to contract ( Table 22.1 ). The result is typically a rhythmic, consistent ventilation rate that provides the body with sufficient amounts of oxygen, while adequately removing carbon dioxide. Summary of Ventilation Regulation System component Function Medullary respiratory center Sets the basic rhythm of breathing Ventral respiratory group (VRG) Generates the breathing rhythm and integrates data coming into the medulla Dorsal respiratory group (DRG) Integrates input from the stretch receptors and the chemoreceptors in the periphery Pontine respiratory group (PRG) Influences and modifies the medulla oblongata’s functions Aortic body Monitors blood PCO 2 , PO 2 , and pH Carotid body Monitors blood PCO 2 , PO 2 , and pH Hypothalamus Monitors emotional state and body temperature Cortical areas of the brain Control voluntary breathing Proprioceptors Send impulses regarding joint and muscle movements Pulmonary irritant reflexes Protect the respiratory zones of the system from foreign material Inflation reflex Protects the lungs from over-inflating Table 22.1 Neurons that innervate the muscles of the respiratory system are responsible for controlling and regulating pulmonary ventilation. The major brain centers involved in pulmonary ventilation are the medulla oblongata and the pontine respiratory group ( Figure 22.20 ). The medulla oblongata contains the dorsal respiratory group (DRG) and the ventral respiratory group (VRG) . The DRG is involved in maintaining a constant breathing rhythm by stimulating the diaphragm and intercostal muscles to contract, resulting in inspiration. When activity in the DRG ceases, it no longer stimulates the diaphragm and intercostals to contract, allowing them to relax, resulting in expiration. The VRG is involved in forced breathing, as the neurons in the VRG stimulate the accessory muscles involved in forced breathing to contract, resulting in forced inspiration. The VRG also stimulates the accessory muscles involved in forced expiration to contract. The second respiratory center of the brain is located within the pons, called the pontine respiratory group, and consists of the apneustic and pneumotaxic centers. The apneustic center is a double cluster of neuronal cell bodies that stimulate neurons in the DRG, controlling the depth of inspiration, particularly for deep breathing. The pneumotaxic center is a network of neurons that inhibits the activity of neurons in the DRG, allowing relaxation after inspiration, and thus controlling the overall rate. Factors That Affect the Rate and Depth of Respiration The respiratory rate and the depth of inspiration are regulated by the medulla oblongata and pons; however, these regions of the brain do so in response to systemic stimuli. It is a dose-response, negative-feedback relationship in which the greater the stimulus, the greater the response. Thus, increasing stimuli results in forced breathing. Multiple systemic factors are involved in stimulating the brain to produce pulmonary ventilation. The major factor that stimulates the medulla oblongata and pons to produce respiration is surprisingly not oxygen concentration, but rather the concentration of carbon dioxide in the blood. As you recall, carbon dioxide is a waste product of cellular respiration and can be toxic. Concentrations of chemicals are sensed by chemoreceptors. A central chemoreceptor is one of the specialized receptors that are located in the brain and brainstem, whereas a peripheral chemoreceptor is one of the specialized receptors located in the carotid arteries and aortic arch. Concentration changes in certain substances, such as carbon dioxide or hydrogen ions, stimulate these receptors, which in turn signal the respiration centers of the brain. In the case of carbon dioxide, as the concentration of CO 2 in the blood increases, it readily diffuses across the blood-brain barrier, where it collects in the extracellular fluid. As will be explained in more detail later, increased carbon dioxide levels lead to increased levels of hydrogen ions, decreasing pH. The increase in hydrogen ions in the brain triggers the central chemoreceptors to stimulate the respiratory centers to initiate contraction of the diaphragm and intercostal muscles. As a result, the rate and depth of respiration increase, allowing more carbon dioxide to be expelled, which brings more air into and out of the lungs promoting a reduction in the blood levels of carbon dioxide, and therefore hydrogen ions, in the blood. In contrast, low levels of carbon dioxide in the blood cause low levels of hydrogen ions in the brain, leading to a decrease in the rate and depth of pulmonary ventilation, producing shallow, slow breathing. Another factor involved in influencing the respiratory activity of the brain is systemic arterial concentrations of hydrogen ions. Increasing carbon dioxide levels can lead to increased H + levels, as mentioned above, as well as other metabolic activities, such as lactic acid accumulation after strenuous exercise. Peripheral chemoreceptors of the aortic arch and carotid arteries sense arterial levels of hydrogen ions. When peripheral chemoreceptors sense decreasing, or more acidic, pH levels, they stimulate an increase in ventilation to remove carbon dioxide from the blood at a quicker rate. Removal of carbon dioxide from the blood helps to reduce hydrogen ions, thus increasing systemic pH. Blood levels of oxygen are also important in influencing respiratory rate. The peripheral chemoreceptors are responsible for sensing large changes in blood oxygen levels. If blood oxygen levels become quite low—about 60 mm Hg or less—then peripheral chemoreceptors stimulate an increase in respiratory activity. The chemoreceptors are only able to sense dissolved oxygen molecules, not the oxygen that is bound to hemoglobin. As you recall, the majority of oxygen is bound by hemoglobin; when dissolved levels of oxygen drop, hemoglobin releases oxygen. Therefore, a large drop in oxygen levels is required to stimulate the chemoreceptors of the aortic arch and carotid arteries. The hypothalamus and other brain regions associated with the limbic system also play roles in influencing the regulation of breathing by interacting with the respiratory centers. The hypothalamus and other regions associated with the limbic system are involved in regulating respiration in response to emotions, pain, and temperature. For example, an increase in body temperature causes an increase in respiratory rate. Feeling excited or the fight-or-flight response will also result in an increase in respiratory rate. Disorders of the... Respiratory System: Sleep Apnea Sleep apnea is a chronic disorder that can occur in children or adults, and is characterized by the cessation of breathing during sleep. These episodes may last for several seconds or several minutes, and may differ in the frequency with which they are experienced. Sleep apnea leads to poor sleep, which is reflected in the symptoms of fatigue, evening napping, irritability, memory problems, and morning headaches. In addition, many individuals with sleep apnea experience a dry throat in the morning after waking from sleep, which may be due to excessive snoring. There are two types of sleep apnea: obstructive sleep apnea and central sleep apnea. Obstructive sleep apnea is caused by an obstruction of the airway during sleep, which can occur at different points in the airway, depending on the underlying cause of the obstruction. For example, the tongue and throat muscles of some individuals with obstructive sleep apnea may relax excessively, causing the muscles to push into the airway. Another example is obesity, which is a known risk factor for sleep apnea, as excess adipose tissue in the neck region can push the soft tissues towards the lumen of the airway, causing the trachea to narrow. In central sleep apnea, the respiratory centers of the brain do not respond properly to rising carbon dioxide levels and therefore do not stimulate the contraction of the diaphragm and intercostal muscles regularly. As a result, inspiration does not occur and breathing stops for a short period. In some cases, the cause of central sleep apnea is unknown. However, some medical conditions, such as stroke and congestive heart failure, may cause damage to the pons or medulla oblongata. In addition, some pharmacologic agents, such as morphine, can affect the respiratory centers, causing a decrease in the respiratory rate. The symptoms of central sleep apnea are similar to those of obstructive sleep apnea. A diagnosis of sleep apnea is usually done during a sleep study, where the patient is monitored in a sleep laboratory for several nights. The patient’s blood oxygen levels, heart rate, respiratory rate, and blood pressure are monitored, as are brain activity and the volume of air that is inhaled and exhaled. Treatment of sleep apnea commonly includes the use of a device called a continuous positive airway pressure (CPAP) machine during sleep. The CPAP machine has a mask that covers the nose, or the nose and mouth, and forces air into the airway at regular intervals. This pressurized air can help to gently force the airway to remain open, allowing more normal ventilation to occur. Other treatments include lifestyle changes to decrease weight, eliminate alcohol and other sleep apnea–promoting drugs, and changes in sleep position. In addition to these treatments, patients with central sleep apnea may need supplemental oxygen during sleep. 22.4 Gas Exchange Learning Objectives By the end of this section, you will be able to: Compare the composition of atmospheric air and alveolar air Describe the mechanisms that drive gas exchange Discuss the importance of sufficient ventilation and perfusion, and how the body adapts when they are insufficient Discuss the process of external respiration Describe the process of internal respiration The purpose of the respiratory system is to perform gas exchange. Pulmonary ventilation provides air to the alveoli for this gas exchange process. At the respiratory membrane, where the alveolar and capillary walls meet, gases move across the membranes, with oxygen entering the bloodstream and carbon dioxide exiting. It is through this mechanism that blood is oxygenated and carbon dioxide, the waste product of cellular respiration, is removed from the body. Gas Exchange In order to understand the mechanisms of gas exchange in the lung, it is important to understand the underlying principles of gases and their behavior. In addition to Boyle’s law, several other gas laws help to describe the behavior of gases. Gas Laws and Air Composition Gas molecules exert force on the surfaces with which they are in contact; this force is called pressure. In natural systems, gases are normally present as a mixture of different types of molecules. For example, the atmosphere consists of oxygen, nitrogen, carbon dioxide, and other gaseous molecules, and this gaseous mixture exerts a certain pressure referred to as atmospheric pressure ( Table 22.2 ). Partial pressure ( P x ) is the pressure of a single type of gas in a mixture of gases. For example, in the atmosphere, oxygen exerts a partial pressure, and nitrogen exerts another partial pressure, independent of the partial pressure of oxygen ( Figure 22.21 ). Total pressure is the sum of all the partial pressures of a gaseous mixture. Dalton’s law describes the behavior of nonreactive gases in a gaseous mixture and states that a specific gas type in a mixture exerts its own pressure; thus, the total pressure exerted by a mixture of gases is the sum of the partial pressures of the gases in the mixture. Partial Pressures of Atmospheric Gases Gas Percent of total composition Partial pressure (mm Hg) Nitrogen (N 2 ) 78.6 597.4 Oxygen (O 2 ) 20.9 158.8 Water (H 2 O) 0.4 3.0 Carbon dioxide (CO 2 ) 0.04 0.3 Others 0.06 0.5 Total composition/total atmospheric pressure 100% 760.0 Table 22.2 Partial pressure is extremely important in predicting the movement of gases. Recall that gases tend to equalize their pressure in two regions that are connected. A gas will move from an area where its partial pressure is higher to an area where its partial pressure is lower. In addition, the greater the partial pressure difference between the two areas, the more rapid is the movement of gases. Solubility of Gases in Liquids Henry’s law describes the behavior of gases when they come into contact with a liquid, such as blood. Henry’s law states that the concentration of gas in a liquid is directly proportional to the solubility and partial pressure of that gas. The greater the partial pressure of the gas, the greater the number of gas molecules that will dissolve in the liquid. The concentration of the gas in a liquid is also dependent on the solubility of the gas in the liquid. For example, although nitrogen is present in the atmosphere, very little nitrogen dissolves into the blood, because the solubility of nitrogen in blood is very low. The exception to this occurs in scuba divers; the composition of the compressed air that divers breathe causes nitrogen to have a higher partial pressure than normal, causing it to dissolve in the blood in greater amounts than normal. Too much nitrogen in the bloodstream results in a serious condition that can be fatal if not corrected. Gas molecules establish an equilibrium between those molecules dissolved in liquid and those in air. The composition of air in the atmosphere and in the alveoli differs. In both cases, the relative concentration of gases is nitrogen > oxygen > water vapor > carbon dioxide. The amount of water vapor present in alveolar air is greater than that in atmospheric air ( Table 22.3 ). Recall that the respiratory system works to humidify incoming air, thereby causing the air present in the alveoli to have a greater amount of water vapor than atmospheric air. In addition, alveolar air contains a greater amount of carbon dioxide and less oxygen than atmospheric air. This is no surprise, as gas exchange removes oxygen from and adds carbon dioxide to alveolar air. Both deep and forced breathing cause the alveolar air composition to be changed more rapidly than during quiet breathing. As a result, the partial pressures of oxygen and carbon dioxide change, affecting the diffusion process that moves these materials across the membrane. This will cause oxygen to enter and carbon dioxide to leave the blood more quickly. Composition and Partial Pressures of Alveolar Air Gas Percent of total composition Partial pressure (mm Hg) Nitrogen (N 2 ) 74.9 569 Oxygen (O 2 ) 13.7 104 Water (H 2 O) 6.2 40 Carbon dioxide (CO 2 ) 5.2 47 Total composition/total alveolar pressure 100% 760.0 Table 22.3 Ventilation and Perfusion Two important aspects of gas exchange in the lung are ventilation and perfusion. Ventilation is the movement of air into and out of the lungs, and perfusion is the flow of blood in the pulmonary capillaries. For gas exchange to be efficient, the volumes involved in ventilation and perfusion should be compatible. However, factors such as regional gravity effects on blood, blocked alveolar ducts, or disease can cause ventilation and perfusion to be imbalanced. The partial pressure of oxygen in alveolar air is about 104 mm Hg, whereas the partial pressure of oxygenated blood in pulmonary veins is about 100 mm Hg. When ventilation is sufficient, oxygen enters the alveoli at a high rate, and the partial pressure of oxygen in the alveoli remains high. In contrast, when ventilation is insufficient, the partial pressure of oxygen in the alveoli drops. Without the large difference in partial pressure between the alveoli and the blood, oxygen does not diffuse efficiently across the respiratory membrane. The body has mechanisms that counteract this problem. In cases when ventilation is not sufficient for an alveolus, the body redirects blood flow to alveoli that are receiving sufficient ventilation. This is achieved by constricting the pulmonary arterioles that serves the dysfunctional alveolus, which redirects blood to other alveoli that have sufficient ventilation. At the same time, the pulmonary arterioles that serve alveoli receiving sufficient ventilation vasodilate, which brings in greater blood flow. Factors such as carbon dioxide, oxygen, and pH levels can all serve as stimuli for adjusting blood flow in the capillary networks associated with the alveoli. Ventilation is regulated by the diameter of the airways, whereas perfusion is regulated by the diameter of the blood vessels. The diameter of the bronchioles is sensitive to the partial pressure of carbon dioxide in the alveoli. A greater partial pressure of carbon dioxide in the alveoli causes the bronchioles to increase their diameter as will a decreased level of oxygen in the blood supply, allowing carbon dioxide to be exhaled from the body at a greater rate. As mentioned above, a greater partial pressure of oxygen in the alveoli causes the pulmonary arterioles to dilate, increasing blood flow. Gas Exchange Gas exchange occurs at two sites in the body: in the lungs, where oxygen is picked up and carbon dioxide is released at the respiratory membrane, and at the tissues, where oxygen is released and carbon dioxide is picked up. External respiration is the exchange of gases with the external environment, and occurs in the alveoli of the lungs. Internal respiration is the exchange of gases with the internal environment, and occurs in the tissues. The actual exchange of gases occurs due to simple diffusion. Energy is not required to move oxygen or carbon dioxide across membranes. Instead, these gases follow pressure gradients that allow them to diffuse. The anatomy of the lung maximizes the diffusion of gases: The respiratory membrane is highly permeable to gases; the respiratory and blood capillary membranes are very thin; and there is a large surface area throughout the lungs. External Respiration The pulmonary artery carries deoxygenated blood into the lungs from the heart, where it branches and eventually becomes the capillary network composed of pulmonary capillaries. These pulmonary capillaries create the respiratory membrane with the alveoli ( Figure 22.22 ). As the blood is pumped through this capillary network, gas exchange occurs. Although a small amount of the oxygen is able to dissolve directly into plasma from the alveoli, most of the oxygen is picked up by erythrocytes (red blood cells) and binds to a protein called hemoglobin, a process described later in this chapter. Oxygenated hemoglobin is red, causing the overall appearance of bright red oxygenated blood, which returns to the heart through the pulmonary veins. Carbon dioxide is released in the opposite direction of oxygen, from the blood to the alveoli. Some of the carbon dioxide is returned on hemoglobin, but can also be dissolved in plasma or is present as a converted form, also explained in greater detail later in this chapter. External respiration occurs as a function of partial pressure differences in oxygen and carbon dioxide between the alveoli and the blood in the pulmonary capillaries. Although the solubility of oxygen in blood is not high, there is a drastic difference in the partial pressure of oxygen in the alveoli versus in the blood of the pulmonary capillaries. This difference is about 64 mm Hg: The partial pressure of oxygen in the alveoli is about 104 mm Hg, whereas its partial pressure in the blood of the capillary is about 40 mm Hg. This large difference in partial pressure creates a very strong pressure gradient that causes oxygen to rapidly cross the respiratory membrane from the alveoli into the blood. The partial pressure of carbon dioxide is also different between the alveolar air and the blood of the capillary. However, the partial pressure difference is less than that of oxygen, about 5 mm Hg. The partial pressure of carbon dioxide in the blood of the capillary is about 45 mm Hg, whereas its partial pressure in the alveoli is about 40 mm Hg. However, the solubility of carbon dioxide is much greater than that of oxygen—by a factor of about 20—in both blood and alveolar fluids. As a result, the relative concentrations of oxygen and carbon dioxide that diffuse across the respiratory membrane are similar. Internal Respiration Internal respiration is gas exchange that occurs at the level of body tissues ( Figure 22.23 ). Similar to external respiration, internal respiration also occurs as simple diffusion due to a partial pressure gradient. However, the partial pressure gradients are opposite of those present at the respiratory membrane. The partial pressure of oxygen in tissues is low, about 40 mm Hg, because oxygen is continuously used for cellular respiration. In contrast, the partial pressure of oxygen in the blood is about 100 mm Hg. This creates a pressure gradient that causes oxygen to dissociate from hemoglobin, diffuse out of the blood, cross the interstitial space, and enter the tissue. Hemoglobin that has little oxygen bound to it loses much of its brightness, so that blood returning to the heart is more burgundy in color. Considering that cellular respiration continuously produces carbon dioxide, the partial pressure of carbon dioxide is lower in the blood than it is in the tissue, causing carbon dioxide to diffuse out of the tissue, cross the interstitial fluid, and enter the blood. It is then carried back to the lungs either bound to hemoglobin, dissolved in plasma, or in a converted form. By the time blood returns to the heart, the partial pressure of oxygen has returned to about 40 mm Hg, and the partial pressure of carbon dioxide has returned to about 45 mm Hg. The blood is then pumped back to the lungs to be oxygenated once again during external respiration. Everyday Connection Hyperbaric Chamber Treatment A type of device used in some areas of medicine that exploits the behavior of gases is hyperbaric chamber treatment. A hyperbaric chamber is a unit that can be sealed and expose a patient to either 100 percent oxygen with increased pressure or a mixture of gases that includes a higher concentration of oxygen than normal atmospheric air, also at a higher partial pressure than the atmosphere. There are two major types of chambers: monoplace and multiplace. Monoplace chambers are typically for one patient, and the staff tending to the patient observes the patient from outside of the chamber ( Figure 22.24 ). Some facilities have special monoplace hyperbaric chambers that allow multiple patients to be treated at once, usually in a sitting or reclining position, to help ease feelings of isolation or claustrophobia. Multiplace chambers are large enough for multiple patients to be treated at one time, and the staff attending these patients is present inside the chamber. In a multiplace chamber, patients are often treated with air via a mask or hood, and the chamber is pressurized. Hyperbaric chamber treatment is based on the behavior of gases. As you recall, gases move from a region of higher partial pressure to a region of lower partial pressure. In a hyperbaric chamber, the atmospheric pressure is increased, causing a greater amount of oxygen than normal to diffuse into the bloodstream of the patient. Hyperbaric chamber therapy is used to treat a variety of medical problems, such as wound and graft healing, anaerobic bacterial infections, and carbon monoxide poisoning. Exposure to and poisoning by carbon monoxide is difficult to reverse, because hemoglobin’s affinity for carbon monoxide is much stronger than its affinity for oxygen, causing carbon monoxide to replace oxygen in the blood. Hyperbaric chamber therapy can treat carbon monoxide poisoning, because the increased atmospheric pressure causes more oxygen to diffuse into the bloodstream. At this increased pressure and increased concentration of oxygen, carbon monoxide is displaced from hemoglobin. Another example is the treatment of anaerobic bacterial infections, which are created by bacteria that cannot or prefer not to live in the presence of oxygen. An increase in blood and tissue levels of oxygen helps to kill the anaerobic bacteria that are responsible for the infection, as oxygen is toxic to anaerobic bacteria. For wounds and grafts, the chamber stimulates the healing process by increasing energy production needed for repair. Increasing oxygen transport allows cells to ramp up cellular respiration and thus ATP production, the energy needed to build new structures. 22.5 Transport of Gases Learning Objectives By the end of this section, you will be able to: Describe the principles of oxygen transport Describe the structure of hemoglobin Compare and contrast fetal and adult hemoglobin Describe the principles of carbon dioxide transport The other major activity in the lungs is the process of respiration, the process of gas exchange. The function of respiration is to provide oxygen for use by body cells during cellular respiration and to eliminate carbon dioxide, a waste product of cellular respiration, from the body. In order for the exchange of oxygen and carbon dioxide to occur, both gases must be transported between the external and internal respiration sites. Although carbon dioxide is more soluble than oxygen in blood, both gases require a specialized transport system for the majority of the gas molecules to be moved between the lungs and other tissues. Oxygen Transport in the Blood Even though oxygen is transported via the blood, you may recall that oxygen is not very soluble in liquids. A small amount of oxygen does dissolve in the blood and is transported in the bloodstream, but it is only about 1.5% of the total amount. The majority of oxygen molecules are carried from the lungs to the body’s tissues by a specialized transport system, which relies on the erythrocyte—the red blood cell. Erythrocytes contain a metalloprotein, hemoglobin, which serves to bind oxygen molecules to the erythrocyte ( Figure 22.25 ). Heme is the portion of hemoglobin that contains iron, and it is heme that binds oxygen. Each hemoglobin molecule contains four iron-containing heme molecules, and because of this, one hemoglobin molecule is capable of carrying up to four molecules of oxygen. As oxygen diffuses across the respiratory membrane from the alveolus to the capillary, it also diffuses into the red blood cell and is bound by hemoglobin. The following reversible chemical reaction describes the production of the final product, oxyhemoglobin (HbO 2 ), which is formed when oxygen binds to hemoglobin. Oxyhemoglobin is a bright red-colored molecule that contributes to the bright red color of oxygenated blood. Hb + O 2 ↔ Hb O 2 Hb + O 2 ↔ Hb O 2 MathType@MTEF@5@5@+=feaagyart1ev2aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLnhiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq=Jc9vqaqpepm0xbba9pwe9Q8fs0=yqaqpepae9pg0FirpepeKkFr0xfr=xfr=xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaGaaeisaiaabkgacaqGGaGaae4kaiaabccacaqGpbWaaSbaaSqaaiaabkdaaeqaaOGaeyiLHSQaaeisaiaabkgacaqGGaGaeyOeI0Iaaeiiaiaab+eadaWgaaWcbaGaaeOmaaqabaaaaa@42D6@ In this formula, Hb represents reduced hemoglobin, that is, hemoglobin that does not have oxygen bound to it. There are multiple factors involved in how readily heme binds to and dissociates from oxygen, which will be discussed in the subsequent sections. Function of Hemoglobin Hemoglobin is composed of subunits, a protein structure that is referred to as a quaternary structure. Each of the four subunits that make up hemoglobin is arranged in a ring-like fashion, with an iron atom covalently bound to the heme in the center of each subunit. Binding of the first oxygen molecule causes a conformational change in hemoglobin that allows the second molecule of oxygen to bind more readily. As each molecule of oxygen is bound, it further facilitates the binding of the next molecule, until all four heme sites are occupied by oxygen. The opposite occurs as well: After the first oxygen molecule dissociates and is “dropped off” at the tissues, the next oxygen molecule dissociates more readily. When all four heme sites are occupied, the hemoglobin is said to be saturated. When one to three heme sites are occupied, the hemoglobin is said to be partially saturated. Therefore, when considering the blood as a whole, the percent of the available heme units that are bound to oxygen at a given time is called hemoglobin saturation. Hemoglobin saturation of 100 percent means that every heme unit in all of the erythrocytes of the body is bound to oxygen. In a healthy individual with normal hemoglobin levels, hemoglobin saturation generally ranges from 95 percent to 99 percent. Oxygen Dissociation from Hemoglobin Partial pressure is an important aspect of the binding of oxygen to and disassociation from heme. An oxygen–hemoglobin dissociation curve is a graph that describes the relationship of partial pressure to the binding of oxygen to heme and its subsequent dissociation from heme ( Figure 22.26 ). Remember that gases travel from an area of higher partial pressure to an area of lower partial pressure. In addition, the affinity of an oxygen molecule for heme increases as more oxygen molecules are bound. Therefore, in the oxygen–hemoglobin saturation curve, as the partial pressure of oxygen increases, a proportionately greater number of oxygen molecules are bound by heme. Not surprisingly, the oxygen–hemoglobin saturation/dissociation curve also shows that the lower the partial pressure of oxygen, the fewer oxygen molecules are bound to heme. As a result, the partial pressure of oxygen plays a major role in determining the degree of binding of oxygen to heme at the site of the respiratory membrane, as well as the degree of dissociation of oxygen from heme at the site of body tissues. The mechanisms behind the oxygen–hemoglobin saturation/dissociation curve also serve as automatic control mechanisms that regulate how much oxygen is delivered to different tissues throughout the body. This is important because some tissues have a higher metabolic rate than others. Highly active tissues, such as muscle, rapidly use oxygen to produce ATP, lowering the partial pressure of oxygen in the tissue to about 20 mm Hg. The partial pressure of oxygen inside capillaries is about 100 mm Hg, so the difference between the two becomes quite high, about 80 mm Hg. As a result, a greater number of oxygen molecules dissociate from hemoglobin and enter the tissues. The reverse is true of tissues, such as adipose (body fat), which have lower metabolic rates. Because less oxygen is used by these cells, the partial pressure of oxygen within such tissues remains relatively high, resulting in fewer oxygen molecules dissociating from hemoglobin and entering the tissue interstitial fluid. Although venous blood is said to be deoxygenated, some oxygen is still bound to hemoglobin in its red blood cells. This provides an oxygen reserve that can be used when tissues suddenly demand more oxygen. Factors other than partial pressure also affect the oxygen–hemoglobin saturation/dissociation curve. For example, a higher temperature promotes hemoglobin and oxygen to dissociate faster, whereas a lower temperature inhibits dissociation (see Figure 22.26 , middle ). However, the human body tightly regulates temperature, so this factor may not affect gas exchange throughout the body. The exception to this is in highly active tissues, which may release a larger amount of energy than is given off as heat. As a result, oxygen readily dissociates from hemoglobin, which is a mechanism that helps to provide active tissues with more oxygen. Certain hormones, such as androgens, epinephrine, thyroid hormones, and growth hormone, can affect the oxygen–hemoglobin saturation/disassociation curve by stimulating the production of a compound called 2,3-bisphosphoglycerate (BPG) by erythrocytes. BPG is a byproduct of glycolysis. Because erythrocytes do not contain mitochondria, glycolysis is the sole method by which these cells produce ATP. BPG promotes the disassociation of oxygen from hemoglobin. Therefore, the greater the concentration of BPG, the more readily oxygen dissociates from hemoglobin, despite its partial pressure. The pH of the blood is another factor that influences the oxygen–hemoglobin saturation/dissociation curve (see Figure 22.26 ). The Bohr effect is a phenomenon that arises from the relationship between pH and oxygen’s affinity for hemoglobin: A lower, more acidic pH promotes oxygen dissociation from hemoglobin. In contrast, a higher, or more basic, pH inhibits oxygen dissociation from hemoglobin. The greater the amount of carbon dioxide in the blood, the more molecules that must be converted, which in turn generates hydrogen ions and thus lowers blood pH. Furthermore, blood pH may become more acidic when certain byproducts of cell metabolism, such as lactic acid, carbonic acid, and carbon dioxide, are released into the bloodstream. Hemoglobin of the Fetus The fetus has its own circulation with its own erythrocytes; however, it is dependent on the mother for oxygen. Blood is supplied to the fetus by way of the umbilical cord, which is connected to the placenta and separated from maternal blood by the chorion. The mechanism of gas exchange at the chorion is similar to gas exchange at the respiratory membrane. However, the partial pressure of oxygen is lower in the maternal blood in the placenta, at about 35 to 50 mm Hg, than it is in maternal arterial blood. The difference in partial pressures between maternal and fetal blood is not large, as the partial pressure of oxygen in fetal blood at the placenta is about 20 mm Hg. Therefore, there is not as much diffusion of oxygen into the fetal blood supply. The fetus’ hemoglobin overcomes this problem by having a greater affinity for oxygen than maternal hemoglobin ( Figure 22.27 ). Both fetal and adult hemoglobin have four subunits, but two of the subunits of fetal hemoglobin have a different structure that causes fetal hemoglobin to have a greater affinity for oxygen than does adult hemoglobin. Carbon Dioxide Transport in the Blood Carbon dioxide is transported by three major mechanisms. The first mechanism of carbon dioxide transport is by blood plasma, as some carbon dioxide molecules dissolve in the blood. The second mechanism is transport in the form of bicarbonate (HCO 3 – ), which also dissolves in plasma. The third mechanism of carbon dioxide transport is similar to the transport of oxygen by erythrocytes ( Figure 22.28 ). Dissolved Carbon Dioxide Although carbon dioxide is not considered to be highly soluble in blood, a small fraction—about 7 to 10 percent—of the carbon dioxide that diffuses into the blood from the tissues dissolves in plasma. The dissolved carbon dioxide then travels in the bloodstream and when the blood reaches the pulmonary capillaries, the dissolved carbon dioxide diffuses across the respiratory membrane into the alveoli, where it is then exhaled during pulmonary ventilation. Bicarbonate Buffer A large fraction—about 70 percent—of the carbon dioxide molecules that diffuse into the blood is transported to the lungs as bicarbonate. Most bicarbonate is produced in erythrocytes after carbon dioxide diffuses into the capillaries, and subsequently into red blood cells. Carbonic anhydrase (CA) causes carbon dioxide and water to form carbonic acid (H 2 CO 3 ), which dissociates into two ions: bicarbonate (HCO 3 – ) and hydrogen (H + ). The following formula depicts this reaction: CO 2  + H 2 O  CA ↔  H 2 CO 3 ↔ H +  + HCO 3 − CO 2  + H 2 O  CA ↔  H 2 CO 3 ↔ H +  + HCO 3 − MathType@MTEF@5@5@+=feaagyart1ev2aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLnhiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq=Jc9vqaqpepm0xbba9pwe9Q8fs0=yqaqpepae9pg0FirpepeKkFr0xfr=xfr=xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaGaae4qaiaab+eadaWgaaWcbaGaaeOmaaqabaGccaqGGaGaae4kaiaabccacaqGibWaaSbaaSqaaiaabkdaaeqaaOGaae4taiaabccajaaOdaahaaqcbaCabKazbakabaqcba6aa8XbaKazbakabaGaae4qaiaabgeaaiaawgoiaaaakiaabccacaqGibWaaSbaaSqaaiaabkdaaeqaaOGaae4qaiaab+eadaWgaaWcbaGaae4maaqabaGccqGHugYQcaqGibWaaWbaaSqabeaacaqGRaaaaOGaaeiiaiaabUcacaqGGaGaaeisaiaaboeacaqGpbWaaSbaaSqaaiaaiodacqGHsislaeqaaaaa@53ED@ Bicarbonate tends to build up in the erythrocytes, so that there is a greater concentration of bicarbonate in the erythrocytes than in the surrounding blood plasma. As a result, some of the bicarbonate will leave the erythrocytes and move down its concentration gradient into the plasma in exchange for chloride (Cl – ) ions. This phenomenon is referred to as the chloride shift and occurs because by exchanging one negative ion for another negative ion, neither the electrical charge of the erythrocytes nor that of the blood is altered. At the pulmonary capillaries, the chemical reaction that produced bicarbonate (shown above) is reversed, and carbon dioxide and water are the products. Much of the bicarbonate in the plasma re-enters the erythrocytes in exchange for chloride ions. Hydrogen ions and bicarbonate ions join to form carbonic acid, which is converted into carbon dioxide and water by carbonic anhydrase. Carbon dioxide diffuses out of the erythrocytes and into the plasma, where it can further diffuse across the respiratory membrane into the alveoli to be exhaled during pulmonary ventilation. Carbaminohemoglobin About 20 percent of carbon dioxide is bound by hemoglobin and is transported to the lungs. Carbon dioxide does not bind to iron as oxygen does; instead, carbon dioxide binds amino acid moieties on the globin portions of hemoglobin to form carbaminohemoglobin , which forms when hemoglobin and carbon dioxide bind. When hemoglobin is not transporting oxygen, it tends to have a bluish-purple tone to it, creating the darker maroon color typical of deoxygenated blood. The following formula depicts this reversible reaction: CO 2  + Hb ↔ HbCO 2 CO 2  + Hb ↔ HbCO 2 MathType@MTEF@5@5@+=feaagyart1ev2aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLnhiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq=Jc9vqaqpepm0xbba9pwe9Q8fs0=yqaqpepae9pg0FirpepeKkFr0xfr=xfr=xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaGaae4qaiaab+eadaWgaaWcbaGaaeOmaaqabaGccaqGGaGaae4kaiaabccacaqGibGaaeOyaiabgsziRkaabIeacaqGIbGaae4qaiaab+eadaWgaaWcbaGaaeOmaaqabaaaaa@422F@ Similar to the transport of oxygen by heme, the binding and dissociation of carbon dioxide to and from hemoglobin is dependent on the partial pressure of carbon dioxide. Because carbon dioxide is released from the lungs, blood that leaves the lungs and reaches body tissues has a lower partial pressure of carbon dioxide than is found in the tissues. As a result, carbon dioxide leaves the tissues because of its higher partial pressure, enters the blood, and then moves into red blood cells, binding to hemoglobin. In contrast, in the pulmonary capillaries, the partial pressure of carbon dioxide is high compared to within the alveoli. As a result, carbon dioxide dissociates readily from hemoglobin and diffuses across the respiratory membrane into the air. In addition to the partial pressure of carbon dioxide, the oxygen saturation of hemoglobin and the partial pressure of oxygen in the blood also influence the affinity of hemoglobin for carbon dioxide. The Haldane effect is a phenomenon that arises from the relationship between the partial pressure of oxygen and the affinity of hemoglobin for carbon dioxide. Hemoglobin that is saturated with oxygen does not readily bind carbon dioxide. However, when oxygen is not bound to heme and the partial pressure of oxygen is low, hemoglobin readily binds to carbon dioxide. Interactive Link Watch this video to see the transport of oxygen from the lungs to the tissues. Why is oxygenated blood bright red, whereas deoxygenated blood tends to be more of a purple color? 22.6 Modifications in Respiratory Functions Learning Objectives By the end of this section, you will be able to: Define the terms hyperpnea and hyperventilation Describe the effect of exercise on the respiratory system Describe the effect of high altitude on the respiratory system Discuss the process of acclimatization At rest, the respiratory system performs its functions at a constant, rhythmic pace, as regulated by the respiratory centers of the brain. At this pace, ventilation provides sufficient oxygen to all the tissues of the body. However, there are times that the respiratory system must alter the pace of its functions in order to accommodate the oxygen demands of the body. Hyperpnea Hyperpnea is an increased depth and rate of ventilation to meet an increase in oxygen demand as might be seen in exercise or disease, particularly diseases that target the respiratory or digestive tracts. This does not significantly alter blood oxygen or carbon dioxide levels, but merely increases the depth and rate of ventilation to meet the demand of the cells. In contrast, hyperventilation is an increased ventilation rate that is independent of the cellular oxygen needs and leads to abnormally low blood carbon dioxide levels and high (alkaline) blood pH. Interestingly, exercise does not cause hyperpnea as one might think. Muscles that perform work during exercise do increase their demand for oxygen, stimulating an increase in ventilation. However, hyperpnea during exercise appears to occur before a drop in oxygen levels within the muscles can occur. Therefore, hyperpnea must be driven by other mechanisms, either instead of or in addition to a drop in oxygen levels. The exact mechanisms behind exercise hyperpnea are not well understood, and some hypotheses are somewhat controversial. However, in addition to low oxygen, high carbon dioxide, and low pH levels, there appears to be a complex interplay of factors related to the nervous system and the respiratory centers of the brain. First, a conscious decision to partake in exercise, or another form of physical exertion, results in a psychological stimulus that may trigger the respiratory centers of the brain to increase ventilation. In addition, the respiratory centers of the brain may be stimulated through the activation of motor neurons that innervate muscle groups that are involved in the physical activity. Finally, physical exertion stimulates proprioceptors, which are receptors located within the muscles, joints, and tendons, which sense movement and stretching; proprioceptors thus create a stimulus that may also trigger the respiratory centers of the brain. These neural factors are consistent with the sudden increase in ventilation that is observed immediately as exercise begins. Because the respiratory centers are stimulated by psychological, motor neuron, and proprioceptor inputs throughout exercise, the fact that there is also a sudden decrease in ventilation immediately after the exercise ends when these neural stimuli cease, further supports the idea that they are involved in triggering the changes of ventilation. High Altitude Effects An increase in altitude results in a decrease in atmospheric pressure. Although the proportion of oxygen relative to gases in the atmosphere remains at 21 percent, its partial pressure decreases ( Table 22.4 ). As a result, it is more difficult for a body to achieve the same level of oxygen saturation at high altitude than at low altitude, due to lower atmospheric pressure. In fact, hemoglobin saturation is lower at high altitudes compared to hemoglobin saturation at sea level. For example, hemoglobin saturation is about 67 percent at 19,000 feet above sea level, whereas it reaches about 98 percent at sea level. Partial Pressure of Oxygen at Different Altitudes Example location Altitude (feet above sea level) Atmospheric pressure (mm Hg) Partial pressure of oxygen (mm Hg) New York City, New York 0 760 159 Boulder, Colorado 5000 632 133 Aspen, Colorado 8000 565 118 Pike’s Peak, Colorado 14,000 447 94 Denali (Mt. McKinley), Alaska 20,000 350 73 Mt. Everest, Tibet 29,000 260 54 Table 22.4 As you recall, partial pressure is extremely important in determining how much gas can cross the respiratory membrane and enter the blood of the pulmonary capillaries. A lower partial pressure of oxygen means that there is a smaller difference in partial pressures between the alveoli and the blood, so less oxygen crosses the respiratory membrane. As a result, fewer oxygen molecules are bound by hemoglobin. Despite this, the tissues of the body still receive a sufficient amount of oxygen during rest at high altitudes. This is due to two major mechanisms. First, the number of oxygen molecules that enter the tissue from the blood is nearly equal between sea level and high altitudes. At sea level, hemoglobin saturation is higher, but only a quarter of the oxygen molecules are actually released into the tissue. At high altitudes, a greater proportion of molecules of oxygen are released into the tissues. Secondly, at high altitudes, a greater amount of BPG is produced by erythrocytes, which enhances the dissociation of oxygen from hemoglobin. Physical exertion, such as skiing or hiking, can lead to altitude sickness due to the low amount of oxygen reserves in the blood at high altitudes. At sea level, there is a large amount of oxygen reserve in venous blood (even though venous blood is thought of as “deoxygenated”) from which the muscles can draw during physical exertion. Because the oxygen saturation is much lower at higher altitudes, this venous reserve is small, resulting in pathological symptoms of low blood oxygen levels. You may have heard that it is important to drink more water when traveling at higher altitudes than you are accustomed to. This is because your body will increase micturition (urination) at high altitudes to counteract the effects of lower oxygen levels. By removing fluids, blood plasma levels drop but not the total number of erythrocytes. In this way, the overall concentration of erythrocytes in the blood increases, which helps tissues obtain the oxygen they need. Acute mountain sickness (AMS) , or altitude sickness, is a condition that results from acute exposure to high altitudes due to a low partial pressure of oxygen at high altitudes. AMS typically can occur at 2400 meters (8000 feet) above sea level. AMS is a result of low blood oxygen levels, as the body has acute difficulty adjusting to the low partial pressure of oxygen. In serious cases, AMS can cause pulmonary or cerebral edema. Symptoms of AMS include nausea, vomiting, fatigue, lightheadedness, drowsiness, feeling disoriented, increased pulse, and nosebleeds. The only treatment for AMS is descending to a lower altitude; however, pharmacologic treatments and supplemental oxygen can improve symptoms. AMS can be prevented by slowly ascending to the desired altitude, allowing the body to acclimate, as well as maintaining proper hydration. Acclimatization Especially in situations where the ascent occurs too quickly, traveling to areas of high altitude can cause AMS. Acclimatization is the process of adjustment that the respiratory system makes due to chronic exposure to a high altitude. Over a period of time, the body adjusts to accommodate the lower partial pressure of oxygen. The low partial pressure of oxygen at high altitudes results in a lower oxygen saturation level of hemoglobin in the blood. In turn, the tissue levels of oxygen are also lower. As a result, the kidneys are stimulated to produce the hormone erythropoietin (EPO), which stimulates the production of erythrocytes, resulting in a greater number of circulating erythrocytes in an individual at a high altitude over a long period. With more red blood cells, there is more hemoglobin to help transport the available oxygen. Even though there is low saturation of each hemoglobin molecule, there will be more hemoglobin present, and therefore more oxygen in the blood. Over time, this allows the person to partake in physical exertion without developing AMS. 22.7 Embryonic Development of the Respiratory System Learning Objectives By the end of this section, you will be able to: Create a timeline of the phases of respiratory development in the fetus Propose reasons for fetal breathing movements Explain how the lungs become inflated after birth Development of the respiratory system begins early in the fetus. It is a complex process that includes many structures, most of which arise from the endoderm. Towards the end of development, the fetus can be observed making breathing movements. Until birth, however, the mother provides all of the oxygen to the fetus as well as removes all of the fetal carbon dioxide via the placenta. Time Line The development of the respiratory system begins at about week 4 of gestation. By week 28, enough alveoli have matured that a baby born prematurely at this time can usually breathe on its own. The respiratory system, however, is not fully developed until early childhood, when a full complement of mature alveoli is present. Weeks 4–7 Respiratory development in the embryo begins around week 4. Ectodermal tissue from the anterior head region invaginates posteriorly to form olfactory pits, which fuse with endodermal tissue of the developing pharynx. An olfactory pit is one of a pair of structures that will enlarge to become the nasal cavity. At about this same time, the lung bud forms. The lung bud is a dome-shaped structure composed of tissue that bulges from the foregut. The foregut is endoderm just inferior to the pharyngeal pouches. The laryngotracheal bud is a structure that forms from the longitudinal extension of the lung bud as development progresses. The portion of this structure nearest the pharynx becomes the trachea, whereas the distal end becomes more bulbous, forming bronchial buds. A bronchial bud is one of a pair of structures that will eventually become the bronchi and all other lower respiratory structures ( Figure 22.29 ). Weeks 7–16 Bronchial buds continue to branch as development progresses until all of the segmental bronchi have been formed. Beginning around week 13, the lumens of the bronchi begin to expand in diameter. By week 16, respiratory bronchioles form. The fetus now has all major lung structures involved in the airway. Weeks 16–24 Once the respiratory bronchioles form, further development includes extensive vascularization, or the development of the blood vessels, as well as the formation of alveolar ducts and alveolar precursors. At about week 19, the respiratory bronchioles have formed. In addition, cells lining the respiratory structures begin to differentiate to form type I and type II pneumocytes. Once type II cells have differentiated, they begin to secrete small amounts of pulmonary surfactant. Around week 20, fetal breathing movements may begin. Weeks 24–Term Major growth and maturation of the respiratory system occurs from week 24 until term. More alveolar precursors develop, and larger amounts of pulmonary surfactant are produced. Surfactant levels are not generally adequate to create effective lung compliance until about the eighth month of pregnancy. The respiratory system continues to expand, and the surfaces that will form the respiratory membrane develop further. At this point, pulmonary capillaries have formed and continue to expand, creating a large surface area for gas exchange. The major milestone of respiratory development occurs at around week 28, when sufficient alveolar precursors have matured so that a baby born prematurely at this time can usually breathe on its own. However, alveoli continue to develop and mature into childhood. A full complement of functional alveoli does not appear until around 8 years of age. Fetal “Breathing” Although the function of fetal breathing movements is not entirely clear, they can be observed starting at 20–21 weeks of development. Fetal breathing movements involve muscle contractions that cause the inhalation of amniotic fluid and exhalation of the same fluid, with pulmonary surfactant and mucus. Fetal breathing movements are not continuous and may include periods of frequent movements and periods of no movements. Maternal factors can influence the frequency of breathing movements. For example, high blood glucose levels, called hyperglycemia, can boost the number of breathing movements. Conversely, low blood glucose levels, called hypoglycemia, can reduce the number of fetal breathing movements. Tobacco use is also known to lower fetal breathing rates. Fetal breathing may help tone the muscles in preparation for breathing movements once the fetus is born. It may also help the alveoli to form and mature. Fetal breathing movements are considered a sign of robust health. Birth Prior to birth, the lungs are filled with amniotic fluid, mucus, and surfactant. As the fetus is squeezed through the birth canal, the fetal thoracic cavity is compressed, expelling much of this fluid. Some fluid remains, however, but is rapidly absorbed by the body shortly after birth. The first inhalation occurs within 10 seconds after birth and not only serves as the first inspiration, but also acts to inflate the lungs. Pulmonary surfactant is critical for inflation to occur, as it reduces the surface tension of the alveoli. Preterm birth around 26 weeks frequently results in severe respiratory distress, although with current medical advancements, some babies may survive. Prior to 26 weeks, sufficient pulmonary surfactant is not produced, and the surfaces for gas exchange have not formed adequately; therefore, survival is low. Disorders of the... Respiratory System: Respiratory Distress Syndrome Respiratory distress syndrome (RDS) primarily occurs in infants born prematurely. Up to 50 percent of infants born between 26 and 28 weeks and fewer than 30 percent of infants born between 30 and 31 weeks develop RDS. RDS results from insufficient production of pulmonary surfactant, thereby preventing the lungs from properly inflating at birth. A small amount of pulmonary surfactant is produced beginning at around 20 weeks; however, this is not sufficient for inflation of the lungs. As a result, dyspnea occurs and gas exchange cannot be performed properly. Blood oxygen levels are low, whereas blood carbon dioxide levels and pH are high. The primary cause of RDS is premature birth, which may be due to a variety of known or unknown causes. Other risk factors include gestational diabetes, cesarean delivery, second-born twins, and family history of RDS. The presence of RDS can lead to other serious disorders, such as septicemia (infection of the blood) or pulmonary hemorrhage. Therefore, it is important that RDS is immediately recognized and treated to prevent death and reduce the risk of developing other disorders. Medical advances have resulted in an improved ability to treat RDS and support the infant until proper lung development can occur. At the time of delivery, treatment may include resuscitation and intubation if the infant does not breathe on his or her own. These infants would need to be placed on a ventilator to mechanically assist with the breathing process. If spontaneous breathing occurs, application of nasal continuous positive airway pressure (CPAP) may be required. In addition, pulmonary surfactant is typically administered. Death due to RDS has been reduced by 50 percent due to the introduction of pulmonary surfactant therapy. Other therapies may include corticosteroids, supplemental oxygen, and assisted ventilation. Supportive therapies, such as temperature regulation, nutritional support, and antibiotics, may be administered to the premature infant as well.
biology
Chapter Outline 12.1 Mendel’s Experiments and the Laws of Probability 12.2 Characteristics and Traits 12.3 Laws of Inheritance Introduction Genetics is the study of heredity. Johann Gregor Mendel set the framework for genetics long before chromosomes or genes had been identified, at a time when meiosis was not well understood. Mendel selected a simple biological system and conducted methodical, quantitative analyses using large sample sizes. Because of Mendel’s work, the fundamental principles of heredity were revealed. We now know that genes, carried on chromosomes, are the basic functional units of heredity with the capability to be replicated, expressed, or mutated. Today, the postulates put forth by Mendel form the basis of classical, or Mendelian, genetics. Not all genes are transmitted from parents to offspring according to Mendelian genetics, but Mendel’s experiments serve as an excellent starting point for thinking about inheritance.
[ { "answer": { "ans_choice": 0, "ans_text": "anther" }, "bloom": null, "hl_context": "<hl> Mendel performed hybridizations , which involve mating two true-breeding individuals that have different traits . <hl> <hl> In the pea , which is naturally self-pollinating , this is done by manually transferring pollen from the anther of a mature pea plant of one variety to the stigma of a separate mature pea plant of the second variety . <hl> In plants , pollen carries the male gametes ( sperm ) to the stigma , a sticky organ that traps pollen and allows the sperm to move down the pistil to the female gametes ( ova ) below . To prevent the pea plant that was receiving pollen from self-fertilizing and confounding his results , Mendel painstakingly removed all of the anthers from the plant ’ s flowers before they had a chance to mature .", "hl_sentences": "Mendel performed hybridizations , which involve mating two true-breeding individuals that have different traits . In the pea , which is naturally self-pollinating , this is done by manually transferring pollen from the anther of a mature pea plant of one variety to the stigma of a separate mature pea plant of the second variety .", "question": { "cloze_format": "Mendel performed hybridizations by transferring pollen from the _______ of the male plant to the female ova.", "normal_format": "Mendel performed hybridizations by transferring pollen from which of the male plant to the female ova?", "question_choices": [ "anther", "pistil", "stigma", "seed" ], "question_id": "fs-id1438253", "question_text": "Mendel performed hybridizations by transferring pollen from the _______ of the male plant to the female ova." }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 1, "ans_text": "seed texture" }, "bloom": "1", "hl_context": "<hl> Mendel demonstrated that the pea-plant characteristics he studied were transmitted as discrete units from parent to offspring . <hl> <hl> As will be discussed , Mendel also determined that different characteristics , like seed color and seed texture , were transmitted independently of one another and could be considered in separate probability analyses . <hl> For instance , performing a cross between a plant with green , wrinkled seeds and a plant with yellow , round seeds still produced offspring that had a 3:1 ratio of green : yellow seeds ( ignoring seed texture ) and a 3:1 ratio of round : wrinkled seeds ( ignoring seed color ) . The characteristics of color and texture did not influence each other .", "hl_sentences": "Mendel demonstrated that the pea-plant characteristics he studied were transmitted as discrete units from parent to offspring . As will be discussed , Mendel also determined that different characteristics , like seed color and seed texture , were transmitted independently of one another and could be considered in separate probability analyses .", "question": { "cloze_format": "___ is one of the seven characteristics that Mendel observed in pea plants.", "normal_format": "Which is one of the seven characteristics that Mendel observed in pea plants?", "question_choices": [ "flower size", "seed texture", "leaf shape", "stem color" ], "question_id": "fs-id2571565", "question_text": "Which is one of the seven characteristics that Mendel observed in pea plants?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 0, "ans_text": "phenotype" }, "bloom": "2", "hl_context": "Two alleles for a given gene in a diploid organism are expressed and interact to produce physical characteristics . <hl> The observable traits expressed by an organism are referred to as its phenotype . <hl> An organism ’ s underlying genetic makeup , consisting of both physically visible and non-expressed alleles , is called its genotype . Mendel ’ s hybridization experiments demonstrate the difference between phenotype and genotype . When true-breeding plants in which one parent had yellow pods and one had green pods were cross-fertilized , all of the F 1 hybrid offspring had yellow pods . That is , the hybrid offspring were phenotypically identical to the true-breeding parent with yellow pods . However , we know that the allele donated by the parent with green pods was not simply lost because it reappeared in some of the F 2 offspring . Therefore , the F 1 plants must have been genotypically different from the parent with yellow pods .", "hl_sentences": "The observable traits expressed by an organism are referred to as its phenotype .", "question": { "cloze_format": "The observable traits expressed by an organism are described as its ________.", "normal_format": "What are the observable traits expressed by an organism described as?", "question_choices": [ "phenotype", "genotype", "alleles", "zygote" ], "question_id": "fs-id1451758", "question_text": "The observable traits expressed by an organism are described as its ________." }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 2, "ans_text": "homozygous" }, "bloom": null, "hl_context": "Observing that true-breeding pea plants with contrasting traits gave rise to F 1 generations that all expressed the dominant trait and F 2 generations that expressed the dominant and recessive traits in a 3:1 ratio , Mendel proposed the law of segregation . This law states that paired unit factors ( genes ) must segregate equally into gametes such that offspring have an equal likelihood of inheriting either factor . <hl> For the F 2 generation of a monohybrid cross , the following three possible combinations of genotypes could result : homozygous dominant , heterozygous , or homozygous recessive . <hl> <hl> Because heterozygotes could arise from two different pathways ( receiving one dominant and one recessive allele from either parent ) , and because heterozygotes and homozygous dominant individuals are phenotypically identical , the law supports Mendel ’ s observed 3:1 phenotypic ratio . <hl> The equal segregation of alleles is the reason we can apply the Punnett square to accurately predict the offspring of parents with known genotypes . The physical basis of Mendel ’ s law of segregation is the first division of meiosis , in which the homologous chromosomes with their different versions of each gene are segregated into daughter nuclei . The role of the meiotic segregation of chromosomes in sexual reproduction was not understood by the scientific community during Mendel ’ s lifetime .", "hl_sentences": "For the F 2 generation of a monohybrid cross , the following three possible combinations of genotypes could result : homozygous dominant , heterozygous , or homozygous recessive . Because heterozygotes could arise from two different pathways ( receiving one dominant and one recessive allele from either parent ) , and because heterozygotes and homozygous dominant individuals are phenotypically identical , the law supports Mendel ’ s observed 3:1 phenotypic ratio .", "question": { "cloze_format": "A recessive trait will be observed in individuals that are ________ for that trait.", "normal_format": "Which recessive trait will be observed in individuals?", "question_choices": [ "heterozygous", "homozygous or heterozygous", "homozygous", "diploid" ], "question_id": "fs-id2186982", "question_text": "A recessive trait will be observed in individuals that are ________ for that trait." }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 3, "ans_text": "incomplete dominance" }, "bloom": "2", "hl_context": "Mendel ’ s results , that traits are inherited as dominant and recessive pairs , contradicted the view at that time that offspring exhibited a blend of their parents ’ traits . However , the heterozygote phenotype occasionally does appear to be intermediate between the two parents . <hl> For example , in the snapdragon , Antirrhinum majus ( Figure 12.7 ) , a cross between a homozygous parent with white flowers ( C W C W ) and a homozygous parent with red flowers ( C R C R ) will produce offspring with pink flowers ( C R C W ) . <hl> <hl> ( Note that different genotypic abbreviations are used for Mendelian extensions to distinguish these patterns from simple dominance and recessiveness . ) <hl> <hl> This pattern of inheritance is described as incomplete dominance , denoting the expression of two contrasting alleles such that the individual displays an intermediate phenotype . <hl> The allele for red flowers is incompletely dominant over the allele for white flowers . However , the results of a heterozygote self-cross can still be predicted , just as with Mendelian dominant and recessive crosses . In this case , the genotypic ratio would be 1 C R C R : 2 C R C W : 1 C W C W , and the phenotypic ratio would be 1:2 : 1 for red :p ink : white .", "hl_sentences": "For example , in the snapdragon , Antirrhinum majus ( Figure 12.7 ) , a cross between a homozygous parent with white flowers ( C W C W ) and a homozygous parent with red flowers ( C R C R ) will produce offspring with pink flowers ( C R C W ) . ( Note that different genotypic abbreviations are used for Mendelian extensions to distinguish these patterns from simple dominance and recessiveness . ) This pattern of inheritance is described as incomplete dominance , denoting the expression of two contrasting alleles such that the individual displays an intermediate phenotype .", "question": { "cloze_format": "If black and white true-breeding mice are mated and the result is all gray offspring, this would be indicative of the ___ inheritance pattern.", "normal_format": "If black and white true-breeding mice are mated and the result is all gray offspring, what inheritance pattern would this be indicative of?", "question_choices": [ "dominance", "codominance", "multiple alleles", "incomplete dominance" ], "question_id": "fs-id2012396", "question_text": "If black and white true-breeding mice are mated and the result is all gray offspring, what inheritance pattern would this be indicative of?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 1, "ans_text": "product rule" }, "bloom": "2", "hl_context": "<hl> While the forked-line method is a diagrammatic approach to keeping track of probabilities in a cross , the probability method gives the proportions of offspring expected to exhibit each phenotype ( or genotype ) without the added visual assistance . <hl> <hl> Both methods make use of the product rule and consider the alleles for each gene separately . <hl> Earlier , we examined the phenotypic proportions for a trihybrid cross using the forked-line method ; now we will use the probability method to examine the genotypic proportions for a cross with even more genes .", "hl_sentences": "While the forked-line method is a diagrammatic approach to keeping track of probabilities in a cross , the probability method gives the proportions of offspring expected to exhibit each phenotype ( or genotype ) without the added visual assistance . Both methods make use of the product rule and consider the alleles for each gene separately .", "question": { "cloze_format": "The probability rule that the forked line and probability methods make use of is called the ___ .", "normal_format": "The forked line and probability methods make use of what probability rule?", "question_choices": [ "test cross", "product rule", "monohybrid rule", "sum rule" ], "question_id": "fs-id1397496", "question_text": "The forked line and probability methods make use of what probability rule?" }, "references_are_paraphrase": null } ]
12
12.1 Mendel’s Experiments and the Laws of Probability Learning Objectives By the end of this section, you will be able to: Describe the scientific reasons for the success of Mendel’s experimental work Describe the expected outcomes of monohybrid crosses involving dominant and recessive alleles Apply the sum and product rules to calculate probabilities Johann Gregor Mendel (1822–1884) ( Figure 12.2 ) was a lifelong learner, teacher, scientist, and man of faith. As a young adult, he joined the Augustinian Abbey of St. Thomas in Brno in what is now the Czech Republic. Supported by the monastery, he taught physics, botany, and natural science courses at the secondary and university levels. In 1856, he began a decade-long research pursuit involving inheritance patterns in honeybees and plants, ultimately settling on pea plants as his primary model system (a system with convenient characteristics used to study a specific biological phenomenon to be applied to other systems). In 1865, Mendel presented the results of his experiments with nearly 30,000 pea plants to the local Natural History Society. He demonstrated that traits are transmitted faithfully from parents to offspring independently of other traits and in dominant and recessive patterns. In 1866, he published his work, Experiments in Plant Hybridization, 1 in the proceedings of the Natural History Society of Brünn. 1 Johann Gregor Mendel, Versuche über Pflanzenhybriden Verhandlungen des naturforschenden Vereines in Brünn, Bd. IV für das Jahr , 1865 Abhandlungen, 3–47. [for English translation see http://www.mendelweb.org/Mendel.plain.html] Mendel’s work went virtually unnoticed by the scientific community that believed, incorrectly, that the process of inheritance involved a blending of parental traits that produced an intermediate physical appearance in offspring; this hypothetical process appeared to be correct because of what we know now as continuous variation. Continuous variation results from the action of many genes to determine a characteristic like human height. Offspring appear to be a “blend” of their parents’ traits when we look at characteristics that exhibit continuous variation. The blending theory of inheritance asserted that the original parental traits were lost or absorbed by the blending in the offspring, but we now know that this is not the case. Mendel was the first researcher to see it. Instead of continuous characteristics, Mendel worked with traits that were inherited in distinct classes (specifically, violet versus white flowers); this is referred to as discontinuous variation . Mendel’s choice of these kinds of traits allowed him to see experimentally that the traits were not blended in the offspring, nor were they absorbed, but rather that they kept their distinctness and could be passed on. In 1868, Mendel became abbot of the monastery and exchanged his scientific pursuits for his pastoral duties. He was not recognized for his extraordinary scientific contributions during his lifetime. In fact, it was not until 1900 that his work was rediscovered, reproduced, and revitalized by scientists on the brink of discovering the chromosomal basis of heredity. Mendel’s Model System Mendel’s seminal work was accomplished using the garden pea, Pisum sativum , to study inheritance. This species naturally self-fertilizes, such that pollen encounters ova within individual flowers. The flower petals remain sealed tightly until after pollination, preventing pollination from other plants. The result is highly inbred, or “true-breeding,” pea plants. These are plants that always produce offspring that look like the parent. By experimenting with true-breeding pea plants, Mendel avoided the appearance of unexpected traits in offspring that might occur if the plants were not true breeding. The garden pea also grows to maturity within one season, meaning that several generations could be evaluated over a relatively short time. Finally, large quantities of garden peas could be cultivated simultaneously, allowing Mendel to conclude that his results did not come about simply by chance. Mendelian Crosses Mendel performed hybridizations , which involve mating two true-breeding individuals that have different traits. In the pea, which is naturally self-pollinating, this is done by manually transferring pollen from the anther of a mature pea plant of one variety to the stigma of a separate mature pea plant of the second variety. In plants, pollen carries the male gametes (sperm) to the stigma, a sticky organ that traps pollen and allows the sperm to move down the pistil to the female gametes (ova) below. To prevent the pea plant that was receiving pollen from self-fertilizing and confounding his results, Mendel painstakingly removed all of the anthers from the plant’s flowers before they had a chance to mature. Plants used in first-generation crosses were called P 0 , or parental generation one, plants ( Figure 12.3 ). Mendel collected the seeds belonging to the P 0 plants that resulted from each cross and grew them the following season. These offspring were called the F 1 , or the first filial ( filial = offspring, daughter or son), generation. Once Mendel examined the characteristics in the F 1 generation of plants, he allowed them to self-fertilize naturally. He then collected and grew the seeds from the F 1 plants to produce the F 2 , or second filial, generation. Mendel’s experiments extended beyond the F 2 generation to the F 3 and F 4 generations, and so on, but it was the ratio of characteristics in the P 0 −F 1 −F 2 generations that were the most intriguing and became the basis for Mendel’s postulates. Garden Pea Characteristics Revealed the Basics of Heredity In his 1865 publication, Mendel reported the results of his crosses involving seven different characteristics, each with two contrasting traits. A trait is defined as a variation in the physical appearance of a heritable characteristic. The characteristics included plant height, seed texture, seed color, flower color, pea pod size, pea pod color, and flower position. For the characteristic of flower color, for example, the two contrasting traits were white versus violet. To fully examine each characteristic, Mendel generated large numbers of F 1 and F 2 plants, reporting results from 19,959 F 2 plants alone. His findings were consistent. What results did Mendel find in his crosses for flower color? First, Mendel confirmed that he had plants that bred true for white or violet flower color. Regardless of how many generations Mendel examined, all self-crossed offspring of parents with white flowers had white flowers, and all self-crossed offspring of parents with violet flowers had violet flowers. In addition, Mendel confirmed that, other than flower color, the pea plants were physically identical. Once these validations were complete, Mendel applied the pollen from a plant with violet flowers to the stigma of a plant with white flowers. After gathering and sowing the seeds that resulted from this cross, Mendel found that 100 percent of the F 1 hybrid generation had violet flowers. Conventional wisdom at that time would have predicted the hybrid flowers to be pale violet or for hybrid plants to have equal numbers of white and violet flowers. In other words, the contrasting parental traits were expected to blend in the offspring. Instead, Mendel’s results demonstrated that the white flower trait in the F 1 generation had completely disappeared. Importantly, Mendel did not stop his experimentation there. He allowed the F 1 plants to self-fertilize and found that, of F 2 -generation plants, 705 had violet flowers and 224 had white flowers. This was a ratio of 3.15 violet flowers per one white flower, or approximately 3:1. When Mendel transferred pollen from a plant with violet flowers to the stigma of a plant with white flowers and vice versa, he obtained about the same ratio regardless of which parent, male or female, contributed which trait. This is called a reciprocal cross —a paired cross in which the respective traits of the male and female in one cross become the respective traits of the female and male in the other cross. For the other six characteristics Mendel examined, the F 1 and F 2 generations behaved in the same way as they had for flower color. One of the two traits would disappear completely from the F 1 generation only to reappear in the F 2 generation at a ratio of approximately 3:1 ( Table 12.1 ). The Results of Mendel’s Garden Pea Hybridizations Characteristic Contrasting P 0 Traits F 1 Offspring Traits F 2 Offspring Traits F 2 Trait Ratios Flower color Violet vs. white 100 percent violet 705 violet 224 white 3.15:1 Flower position Axial vs. terminal 100 percent axial 651 axial 207 terminal 3.14:1 Plant height Tall vs. dwarf 100 percent tall 787 tall 277 dwarf 2.84:1 Seed texture Round vs. wrinkled 100 percent round 5,474 round 1,850 wrinkled 2.96:1 Seed color Yellow vs. green 100 percent yellow 6,022 yellow 2,001 green 3.01:1 Pea pod texture Inflated vs. constricted 100 percent inflated 882 inflated 299 constricted 2.95:1 Pea pod color Green vs. yellow 100 percent green 428 green 152 yellow 2.82:1 Table 12.1 Upon compiling his results for many thousands of plants, Mendel concluded that the characteristics could be divided into expressed and latent traits. He called these, respectively, dominant and recessive traits. Dominant traits are those that are inherited unchanged in a hybridization. Recessive traits become latent, or disappear, in the offspring of a hybridization. The recessive trait does, however, reappear in the progeny of the hybrid offspring. An example of a dominant trait is the violet-flower trait. For this same characteristic (flower color), white-colored flowers are a recessive trait. The fact that the recessive trait reappeared in the F 2 generation meant that the traits remained separate (not blended) in the plants of the F 1 generation. Mendel also proposed that plants possessed two copies of the trait for the flower-color characteristic, and that each parent transmitted one of its two copies to its offspring, where they came together. Moreover, the physical observation of a dominant trait could mean that the genetic composition of the organism included two dominant versions of the characteristic or that it included one dominant and one recessive version. Conversely, the observation of a recessive trait meant that the organism lacked any dominant versions of this characteristic. So why did Mendel repeatedly obtain 3:1 ratios in his crosses? To understand how Mendel deduced the basic mechanisms of inheritance that lead to such ratios, we must first review the laws of probability. Probability Basics Probabilities are mathematical measures of likelihood. The empirical probability of an event is calculated by dividing the number of times the event occurs by the total number of opportunities for the event to occur. It is also possible to calculate theoretical probabilities by dividing the number of times that an event is expected to occur by the number of times that it could occur. Empirical probabilities come from observations, like those of Mendel. Theoretical probabilities come from knowing how the events are produced and assuming that the probabilities of individual outcomes are equal. A probability of one for some event indicates that it is guaranteed to occur, whereas a probability of zero indicates that it is guaranteed not to occur. An example of a genetic event is a round seed produced by a pea plant. In his experiment, Mendel demonstrated that the probability of the event “round seed” occurring was one in the F 1 offspring of true-breeding parents, one of which has round seeds and one of which has wrinkled seeds. When the F 1 plants were subsequently self-crossed, the probability of any given F 2 offspring having round seeds was now three out of four. In other words, in a large population of F 2 offspring chosen at random, 75 percent were expected to have round seeds, whereas 25 percent were expected to have wrinkled seeds. Using large numbers of crosses, Mendel was able to calculate probabilities and use these to predict the outcomes of other crosses. The Product Rule and Sum Rule Mendel demonstrated that the pea-plant characteristics he studied were transmitted as discrete units from parent to offspring. As will be discussed, Mendel also determined that different characteristics, like seed color and seed texture, were transmitted independently of one another and could be considered in separate probability analyses. For instance, performing a cross between a plant with green, wrinkled seeds and a plant with yellow, round seeds still produced offspring that had a 3:1 ratio of green:yellow seeds (ignoring seed texture) and a 3:1 ratio of round:wrinkled seeds (ignoring seed color). The characteristics of color and texture did not influence each other. The product rule of probability can be applied to this phenomenon of the independent transmission of characteristics. The product rule states that the probability of two independent events occurring together can be calculated by multiplying the individual probabilities of each event occurring alone. To demonstrate the product rule, imagine that you are rolling a six-sided die (D) and flipping a penny (P) at the same time. The die may roll any number from 1–6 (D # ), whereas the penny may turn up heads (P H ) or tails (P T ). The outcome of rolling the die has no effect on the outcome of flipping the penny and vice versa. There are 12 possible outcomes of this action ( Table 12.2 ), and each event is expected to occur with equal probability. Twelve Equally Likely Outcomes of Rolling a Die and Flipping a Penny Rolling Die Flipping Penny D 1 P H D 1 P T D 2 P H D 2 P T D 3 P H D 3 P T D 4 P H D 4 P T D 5 P H D 5 P T D 6 P H D 6 P T Table 12.2 Of the 12 possible outcomes, the die has a 2/12 (or 1/6) probability of rolling a two, and the penny has a 6/12 (or 1/2) probability of coming up heads. By the product rule, the probability that you will obtain the combined outcome 2 and heads is: (D 2 ) x (P H ) = (1/6) x (1/2) or 1/12 ( Table 12.3 ). Notice the word “and” in the description of the probability. The “and” is a signal to apply the product rule. For example, consider how the product rule is applied to the dihybrid cross: the probability of having both dominant traits in the F 2 progeny is the product of the probabilities of having the dominant trait for each characteristic, as shown here: 3 4   ×   3 4   =   ​ 9 16 3 4   ×   3 4   =   ​ 9 16 On the other hand, the sum rule of probability is applied when considering two mutually exclusive outcomes that can come about by more than one pathway. The sum rule states that the probability of the occurrence of one event or the other event, of two mutually exclusive events, is the sum of their individual probabilities. Notice the word “or” in the description of the probability. The “or” indicates that you should apply the sum rule. In this case, let’s imagine you are flipping a penny (P) and a quarter (Q). What is the probability of one coin coming up heads and one coin coming up tails? This outcome can be achieved by two cases: the penny may be heads (P H ) and the quarter may be tails (Q T ), or the quarter may be heads (Q H ) and the penny may be tails (P T ). Either case fulfills the outcome. By the sum rule, we calculate the probability of obtaining one head and one tail as [(P H ) × (Q T )] + [(Q H ) × (P T )] = [(1/2) × (1/2)] + [(1/2) × (1/2)] = 1/2 ( Table 12.3 ). You should also notice that we used the product rule to calculate the probability of P H and Q T , and also the probability of P T and Q H , before we summed them. Again, the sum rule can be applied to show the probability of having just one dominant trait in the F 2 generation of a dihybrid cross: 3 16   +   3 4   =   ​ 15 16 3 16   +   3 4   =   ​ 15 16 The Product Rule and Sum Rule Product Rule Sum Rule For independent events A and B, the probability (P) of them both occurring (A and B) is (P A × P B ) For mutually exclusive events A and B, the probability (P) that at least one occurs (A or B) is (P A + P B ) Table 12.3 To use probability laws in practice, it is necessary to work with large sample sizes because small sample sizes are prone to deviations caused by chance. The large quantities of pea plants that Mendel examined allowed him calculate the probabilities of the traits appearing in his F 2 generation. As you will learn, this discovery meant that when parental traits were known, the offspring’s traits could be predicted accurately even before fertilization. 12.2 Characteristics and Traits Learning Objectives By the end of this section, you will be able to: Explain the relationship between genotypes and phenotypes in dominant and recessive gene systems Develop a Punnett square to calculate the expected proportions of genotypes and phenotypes in a monohybrid cross Explain the purpose and methods of a test cross Identify non-Mendelian inheritance patterns such as incomplete dominance, codominance, recessive lethals, multiple alleles, and sex linkage The seven characteristics that Mendel evaluated in his pea plants were each expressed as one of two versions, or traits. The physical expression of characteristics is accomplished through the expression of genes carried on chromosomes. The genetic makeup of peas consists of two similar or homologous copies of each chromosome, one from each parent. Each pair of homologous chromosomes has the same linear order of genes. In other words, peas are diploid organisms in that they have two copies of each chromosome. The same is true for many other plants and for virtually all animals. Diploid organisms utilize meiosis to produce haploid gametes, which contain one copy of each homologous chromosome that unite at fertilization to create a diploid zygote. For cases in which a single gene controls a single characteristic, a diploid organism has two genetic copies that may or may not encode the same version of that characteristic. Gene variants that arise by mutation and exist at the same relative locations on homologous chromosomes are called alleles . Mendel examined the inheritance of genes with just two allele forms, but it is common to encounter more than two alleles for any given gene in a natural population. Phenotypes and Genotypes Two alleles for a given gene in a diploid organism are expressed and interact to produce physical characteristics. The observable traits expressed by an organism are referred to as its phenotype . An organism’s underlying genetic makeup, consisting of both physically visible and non-expressed alleles, is called its genotype . Mendel’s hybridization experiments demonstrate the difference between phenotype and genotype. When true-breeding plants in which one parent had yellow pods and one had green pods were cross-fertilized, all of the F 1 hybrid offspring had yellow pods. That is, the hybrid offspring were phenotypically identical to the true-breeding parent with yellow pods. However, we know that the allele donated by the parent with green pods was not simply lost because it reappeared in some of the F 2 offspring. Therefore, the F 1 plants must have been genotypically different from the parent with yellow pods. The P 1 plants that Mendel used in his experiments were each homozygous for the trait he was studying. Diploid organisms that are homozygous at a given gene, or locus, have two identical alleles for that gene on their homologous chromosomes. Mendel’s parental pea plants always bred true because both of the gametes produced carried the same trait. When P 1 plants with contrasting traits were cross-fertilized, all of the offspring were heterozygous for the contrasting trait, meaning that their genotype reflected that they had different alleles for the gene being examined. Dominant and Recessive Alleles Our discussion of homozygous and heterozygous organisms brings us to why the F 1 heterozygous offspring were identical to one of the parents, rather than expressing both alleles. In all seven pea-plant characteristics, one of the two contrasting alleles was dominant, and the other was recessive. Mendel called the dominant allele the expressed unit factor; the recessive allele was referred to as the latent unit factor. We now know that these so-called unit factors are actually genes on homologous chromosome pairs. For a gene that is expressed in a dominant and recessive pattern, homozygous dominant and heterozygous organisms will look identical (that is, they will have different genotypes but the same phenotype). The recessive allele will only be observed in homozygous recessive individuals ( Table 12.4 ). Human Inheritance in Dominant and Recessive Patterns Dominant Traits Recessive Traits Achondroplasia Albinism Brachydactyly Cystic fibrosis Huntington’s disease Duchenne muscular dystrophy Marfan syndrome Galactosemia Neurofibromatosis Phenylketonuria Widow’s peak Sickle-cell anemia Wooly hair Tay-Sachs disease Table 12.4 Several conventions exist for referring to genes and alleles. For the purposes of this chapter, we will abbreviate genes using the first letter of the gene’s corresponding dominant trait. For example, violet is the dominant trait for a pea plant’s flower color, so the flower-color gene would be abbreviated as V (note that it is customary to italicize gene designations). Furthermore, we will use uppercase and lowercase letters to represent dominant and recessive alleles, respectively. Therefore, we would refer to the genotype of a homozygous dominant pea plant with violet flowers as VV , a homozygous recessive pea plant with white flowers as vv , and a heterozygous pea plant with violet flowers as Vv . The Punnett Square Approach for a Monohybrid Cross When fertilization occurs between two true-breeding parents that differ in only one characteristic, the process is called a monohybrid cross, and the resulting offspring are monohybrids. Mendel performed seven monohybrid crosses involving contrasting traits for each characteristic. On the basis of his results in F 1 and F 2 generations, Mendel postulated that each parent in the monohybrid cross contributed one of two paired unit factors to each offspring, and every possible combination of unit factors was equally likely. To demonstrate a monohybrid cross, consider the case of true-breeding pea plants with yellow versus green pea seeds. The dominant seed color is yellow; therefore, the parental genotypes were YY for the plants with yellow seeds and yy for the plants with green seeds, respectively. A Punnett square , devised by the British geneticist Reginald Punnett, can be drawn that applies the rules of probability to predict the possible outcomes of a genetic cross or mating and their expected frequencies. To prepare a Punnett square, all possible combinations of the parental alleles are listed along the top (for one parent) and side (for the other parent) of a grid, representing their meiotic segregation into haploid gametes. Then the combinations of egg and sperm are made in the boxes in the table to show which alleles are combining. Each box then represents the diploid genotype of a zygote, or fertilized egg, that could result from this mating. Because each possibility is equally likely, genotypic ratios can be determined from a Punnett square. If the pattern of inheritance (dominant or recessive) is known, the phenotypic ratios can be inferred as well. For a monohybrid cross of two true-breeding parents, each parent contributes one type of allele. In this case, only one genotype is possible. All offspring are Yy and have yellow seeds ( Figure 12.4 ). A self-cross of one of the Yy heterozygous offspring can be represented in a 2 × 2 Punnett square because each parent can donate one of two different alleles. Therefore, the offspring can potentially have one of four allele combinations: YY , Yy , yY , or yy ( Figure 12.4 ). Notice that there are two ways to obtain the Yy genotype: a Y from the egg and a y from the sperm, or a y from the egg and a Y from the sperm. Both of these possibilities must be counted. Recall that Mendel’s pea-plant characteristics behaved in the same way in reciprocal crosses. Therefore, the two possible heterozygous combinations produce offspring that are genotypically and phenotypically identical despite their dominant and recessive alleles deriving from different parents. They are grouped together. Because fertilization is a random event, we expect each combination to be equally likely and for the offspring to exhibit a ratio of YY : Yy : yy genotypes of 1:2:1 ( Figure 12.4 ). Furthermore, because the YY and Yy offspring have yellow seeds and are phenotypically identical, applying the sum rule of probability, we expect the offspring to exhibit a phenotypic ratio of 3 yellow:1 green. Indeed, working with large sample sizes, Mendel observed approximately this ratio in every F 2 generation resulting from crosses for individual traits. Mendel validated these results by performing an F 3 cross in which he self-crossed the dominant- and recessive-expressing F 2 plants. When he self-crossed the plants expressing green seeds, all of the offspring had green seeds, confirming that all green seeds had homozygous genotypes of yy . When he self-crossed the F 2 plants expressing yellow seeds, he found that one-third of the plants bred true, and two-thirds of the plants segregated at a 3:1 ratio of yellow:green seeds. In this case, the true-breeding plants had homozygous ( YY ) genotypes, whereas the segregating plants corresponded to the heterozygous ( Yy ) genotype. When these plants self-fertilized, the outcome was just like the F 1 self-fertilizing cross. The Test Cross Distinguishes the Dominant Phenotype Beyond predicting the offspring of a cross between known homozygous or heterozygous parents, Mendel also developed a way to determine whether an organism that expressed a dominant trait was a heterozygote or a homozygote. Called the test cross , this technique is still used by plant and animal breeders. In a test cross, the dominant-expressing organism is crossed with an organism that is homozygous recessive for the same characteristic. If the dominant-expressing organism is a homozygote, then all F 1 offspring will be heterozygotes expressing the dominant trait ( Figure 12.5 ). Alternatively, if the dominant expressing organism is a heterozygote, the F 1 offspring will exhibit a 1:1 ratio of heterozygotes and recessive homozygotes ( Figure 12.5 ). The test cross further validates Mendel’s postulate that pairs of unit factors segregate equally. Visual Connection In pea plants, round peas ( R ) are dominant to wrinkled peas ( r ). You do a test cross between a pea plant with wrinkled peas (genotype rr ) and a plant of unknown genotype that has round peas. You end up with three plants, all which have round peas. From this data, can you tell if the round pea parent plant is homozygous dominant or heterozygous? If the round pea parent plant is heterozygous, what is the probability that a random sample of 3 progeny peas will all be round? Many human diseases are genetically inherited. A healthy person in a family in which some members suffer from a recessive genetic disorder may want to know if he or she has the disease-causing gene and what risk exists of passing the disorder on to his or her offspring. Of course, doing a test cross in humans is unethical and impractical. Instead, geneticists use pedigree analysis to study the inheritance pattern of human genetic diseases ( Figure 12.6 ). Visual Connection What are the genotypes of the individuals labeled 1, 2 and 3? Alternatives to Dominance and Recessiveness Mendel’s experiments with pea plants suggested that: (1) two “units” or alleles exist for every gene; (2) alleles maintain their integrity in each generation (no blending); and (3) in the presence of the dominant allele, the recessive allele is hidden and makes no contribution to the phenotype. Therefore, recessive alleles can be “carried” and not expressed by individuals. Such heterozygous individuals are sometimes referred to as “carriers.” Further genetic studies in other plants and animals have shown that much more complexity exists, but that the fundamental principles of Mendelian genetics still hold true. In the sections to follow, we consider some of the extensions of Mendelism. If Mendel had chosen an experimental system that exhibited these genetic complexities, it’s possible that he would not have understood what his results meant. Incomplete Dominance Mendel’s results, that traits are inherited as dominant and recessive pairs, contradicted the view at that time that offspring exhibited a blend of their parents’ traits. However, the heterozygote phenotype occasionally does appear to be intermediate between the two parents. For example, in the snapdragon, Antirrhinum majus ( Figure 12.7 ), a cross between a homozygous parent with white flowers ( C W C W ) and a homozygous parent with red flowers ( C R C R ) will produce offspring with pink flowers ( C R C W ). (Note that different genotypic abbreviations are used for Mendelian extensions to distinguish these patterns from simple dominance and recessiveness.) This pattern of inheritance is described as incomplete dominance , denoting the expression of two contrasting alleles such that the individual displays an intermediate phenotype. The allele for red flowers is incompletely dominant over the allele for white flowers. However, the results of a heterozygote self-cross can still be predicted, just as with Mendelian dominant and recessive crosses. In this case, the genotypic ratio would be 1 C R C R :2 C R C W :1 C W C W , and the phenotypic ratio would be 1:2:1 for red:pink:white. Codominance A variation on incomplete dominance is codominance , in which both alleles for the same characteristic are simultaneously expressed in the heterozygote. An example of codominance is the MN blood groups of humans. The M and N alleles are expressed in the form of an M or N antigen present on the surface of red blood cells. Homozygotes ( L M L M and L N L N ) express either the M or the N allele, and heterozygotes ( L M L N ) express both alleles equally. In a self-cross between heterozygotes expressing a codominant trait, the three possible offspring genotypes are phenotypically distinct. However, the 1:2:1 genotypic ratio characteristic of a Mendelian monohybrid cross still applies. Multiple Alleles Mendel implied that only two alleles, one dominant and one recessive, could exist for a given gene. We now know that this is an oversimplification. Although individual humans (and all diploid organisms) can only have two alleles for a given gene, multiple alleles may exist at the population level such that many combinations of two alleles are observed. Note that when many alleles exist for the same gene, the convention is to denote the most common phenotype or genotype among wild animals as the wild type (often abbreviated “+”); this is considered the standard or norm. All other phenotypes or genotypes are considered variants of this standard, meaning that they deviate from the wild type. The variant may be recessive or dominant to the wild-type allele. An example of multiple alleles is coat color in rabbits ( Figure 12.8 ). Here, four alleles exist for the c gene. The wild-type version, C + C + , is expressed as brown fur. The chinchilla phenotype, c ch c ch , is expressed as black-tipped white fur. The Himalayan phenotype, c h c h , has black fur on the extremities and white fur elsewhere. Finally, the albino, or “colorless” phenotype, cc , is expressed as white fur. In cases of multiple alleles, dominance hierarchies can exist. In this case, the wild-type allele is dominant over all the others, chinchilla is incompletely dominant over Himalayan and albino, and Himalayan is dominant over albino. This hierarchy, or allelic series, was revealed by observing the phenotypes of each possible heterozygote offspring. The complete dominance of a wild-type phenotype over all other mutants often occurs as an effect of “dosage” of a specific gene product, such that the wild-type allele supplies the correct amount of gene product whereas the mutant alleles cannot. For the allelic series in rabbits, the wild-type allele may supply a given dosage of fur pigment, whereas the mutants supply a lesser dosage or none at all. Interestingly, the Himalayan phenotype is the result of an allele that produces a temperature-sensitive gene product that only produces pigment in the cooler extremities of the rabbit’s body. Alternatively, one mutant allele can be dominant over all other phenotypes, including the wild type. This may occur when the mutant allele somehow interferes with the genetic message so that even a heterozygote with one wild-type allele copy expresses the mutant phenotype. One way in which the mutant allele can interfere is by enhancing the function of the wild-type gene product or changing its distribution in the body. One example of this is the Antennapedia mutation in Drosophila ( Figure 12.9 ). In this case, the mutant allele expands the distribution of the gene product, and as a result, the Antennapedia heterozygote develops legs on its head where its antennae should be. Evolution Connection Multiple Alleles Confer Drug Resistance in the Malaria Parasite Malaria is a parasitic disease in humans that is transmitted by infected female mosquitoes, including Anopheles gambiae ( Figure 12.10 a ), and is characterized by cyclic high fevers, chills, flu-like symptoms, and severe anemia. Plasmodium falciparum and P. vivax are the most common causative agents of malaria, and P. falciparum is the most deadly ( Figure 12.10 b ) . When promptly and correctly treated, P. falciparum malaria has a mortality rate of 0.1 percent. However, in some parts of the world, the parasite has evolved resistance to commonly used malaria treatments, so the most effective malarial treatments can vary by geographic region. In Southeast Asia, Africa, and South America, P. falciparum has developed resistance to the anti-malarial drugs chloroquine, mefloquine, and sulfadoxine-pyrimethamine. P. falciparum , which is haploid during the life stage in which it is infectious to humans, has evolved multiple drug-resistant mutant alleles of the dhps gene. Varying degrees of sulfadoxine resistance are associated with each of these alleles. Being haploid, P. falciparum needs only one drug-resistant allele to express this trait. In Southeast Asia, different sulfadoxine-resistant alleles of the dhps gene are localized to different geographic regions. This is a common evolutionary phenomenon that occurs because drug-resistant mutants arise in a population and interbreed with other P. falciparum isolates in close proximity. Sulfadoxine-resistant parasites cause considerable human hardship in regions where this drug is widely used as an over-the-counter malaria remedy. As is common with pathogens that multiply to large numbers within an infection cycle, P. falciparum evolves relatively rapidly (over a decade or so) in response to the selective pressure of commonly used anti-malarial drugs. For this reason, scientists must constantly work to develop new drugs or drug combinations to combat the worldwide malaria burden. 2 2 Sumiti Vinayak, et al., “Origin and Evolution of Sulfadoxine Resistant Plasmodium falciparum ,” Public Library of Science Pathogens 6, no. 3 (2010): e1000830, doi:10.1371/journal.ppat.1000830. X-Linked Traits In humans, as well as in many other animals and some plants, the sex of the individual is determined by sex chromosomes. The sex chromosomes are one pair of non-homologous chromosomes. Until now, we have only considered inheritance patterns among non-sex chromosomes, or autosomes . In addition to 22 homologous pairs of autosomes, human females have a homologous pair of X chromosomes, whereas human males have an XY chromosome pair. Although the Y chromosome contains a small region of similarity to the X chromosome so that they can pair during meiosis, the Y chromosome is much shorter and contains many fewer genes. When a gene being examined is present on the X chromosome, but not on the Y chromosome, it is said to be X-linked . Eye color in Drosophila was one of the first X-linked traits to be identified. Thomas Hunt Morgan mapped this trait to the X chromosome in 1910. Like humans, Drosophila males have an XY chromosome pair, and females are XX. In flies, the wild-type eye color is red (X W ) and it is dominant to white eye color (X w ) ( Figure 12.11 ). Because of the location of the eye-color gene, reciprocal crosses do not produce the same offspring ratios. Males are said to be hemizygous , because they have only one allele for any X-linked characteristic. Hemizygosity makes the descriptions of dominance and recessiveness irrelevant for XY males. Drosophila males lack a second allele copy on the Y chromosome; that is, their genotype can only be X W Y or X w Y. In contrast, females have two allele copies of this gene and can be X W X W , X W X w , or X w X w . In an X-linked cross, the genotypes of F 1 and F 2 offspring depend on whether the recessive trait was expressed by the male or the female in the P 1 generation. With regard to Drosophila eye color, when the P 1 male expresses the white-eye phenotype and the female is homozygous red-eyed, all members of the F 1 generation exhibit red eyes ( Figure 12.12 ). The F 1 females are heterozygous (X W X w ), and the males are all X W Y, having received their X chromosome from the homozygous dominant P 1 female and their Y chromosome from the P 1 male. A subsequent cross between the X W X w female and the X W Y male would produce only red-eyed females (with X W X W or X W X w genotypes) and both red- and white-eyed males (with X W Y or X w Y genotypes). Now, consider a cross between a homozygous white-eyed female and a male with red eyes. The F 1 generation would exhibit only heterozygous red-eyed females (X W X w ) and only white-eyed males (X w Y). Half of the F 2 females would be red-eyed (X W X w ) and half would be white-eyed (X w X w ). Similarly, half of the F 2 males would be red-eyed (X W Y) and half would be white-eyed (X w Y). Visual Connection What ratio of offspring would result from a cross between a white-eyed male and a female that is heterozygous for red eye color? Discoveries in fruit fly genetics can be applied to human genetics. When a female parent is homozygous for a recessive X-linked trait, she will pass the trait on to 100 percent of her offspring. Her male offspring are, therefore, destined to express the trait, as they will inherit their father's Y chromosome. In humans, the alleles for certain conditions (some forms of color blindness, hemophilia, and muscular dystrophy) are X-linked. Females who are heterozygous for these diseases are said to be carriers and may not exhibit any phenotypic effects. These females will pass the disease to half of their sons and will pass carrier status to half of their daughters; therefore, recessive X-linked traits appear more frequently in males than females. In some groups of organisms with sex chromosomes, the sex with the non-homologous sex chromosomes is the female rather than the male. This is the case for all birds. In this case, sex-linked traits will be more likely to appear in the female, in which they are hemizygous. Human Sex-linked Disorders Sex-linkage studies in Morgan’s laboratory provided the fundamentals for understanding X-linked recessive disorders in humans, which include red-green color blindness, and Types A and B hemophilia. Because human males need to inherit only one recessive mutant X allele to be affected, X-linked disorders are disproportionately observed in males. Females must inherit recessive X-linked alleles from both of their parents in order to express the trait. When they inherit one recessive X-linked mutant allele and one dominant X-linked wild-type allele, they are carriers of the trait and are typically unaffected. Carrier females can manifest mild forms of the trait due to the inactivation of the dominant allele located on one of the X chromosomes. However, female carriers can contribute the trait to their sons, resulting in the son exhibiting the trait, or they can contribute the recessive allele to their daughters, resulting in the daughters being carriers of the trait ( Figure 12.13 ). Although some Y-linked recessive disorders exist, typically they are associated with infertility in males and are therefore not transmitted to subsequent generations. Link to Learning Watch this video to learn more about sex-linked traits. Click to view content Lethality A large proportion of genes in an individual’s genome are essential for survival. Occasionally, a nonfunctional allele for an essential gene can arise by mutation and be transmitted in a population as long as individuals with this allele also have a wild-type, functional copy. The wild-type allele functions at a capacity sufficient to sustain life and is therefore considered to be dominant over the nonfunctional allele. However, consider two heterozygous parents that have a genotype of wild-type/nonfunctional mutant for a hypothetical essential gene. In one quarter of their offspring, we would expect to observe individuals that are homozygous recessive for the nonfunctional allele. Because the gene is essential, these individuals might fail to develop past fertilization, die in utero , or die later in life, depending on what life stage requires this gene. An inheritance pattern in which an allele is only lethal in the homozygous form and in which the heterozygote may be normal or have some altered non-lethal phenotype is referred to as recessive lethal . For crosses between heterozygous individuals with a recessive lethal allele that causes death before birth when homozygous, only wild-type homozygotes and heterozygotes would be observed. The genotypic ratio would therefore be 2:1. In other instances, the recessive lethal allele might also exhibit a dominant (but not lethal) phenotype in the heterozygote. For instance, the recessive lethal Curly allele in Drosophila affects wing shape in the heterozygote form but is lethal in the homozygote. A single copy of the wild-type allele is not always sufficient for normal functioning or even survival. The dominant lethal inheritance pattern is one in which an allele is lethal both in the homozygote and the heterozygote; this allele can only be transmitted if the lethality phenotype occurs after reproductive age. Individuals with mutations that result in dominant lethal alleles fail to survive even in the heterozygote form. Dominant lethal alleles are very rare because, as you might expect, the allele only lasts one generation and is not transmitted. However, just as the recessive lethal allele might not immediately manifest the phenotype of death, dominant lethal alleles also might not be expressed until adulthood. Once the individual reaches reproductive age, the allele may be unknowingly passed on, resulting in a delayed death in both generations. An example of this in humans is Huntington’s disease, in which the nervous system gradually wastes away ( Figure 12.14 ). People who are heterozygous for the dominant Huntington allele ( Hh ) will inevitably develop the fatal disease. However, the onset of Huntington’s disease may not occur until age 40, at which point the afflicted persons may have already passed the allele to 50 percent of their offspring. 12.3 Laws of Inheritance Learning Objectives By the end of this section, you will be able to: Explain Mendel’s law of segregation and independent assortment in terms of genetics and the events of meiosis Use the forked-line method and the probability rules to calculate the probability of genotypes and phenotypes from multiple gene crosses Explain the effect of linkage and recombination on gamete genotypes Explain the phenotypic outcomes of epistatic effects between genes Mendel generalized the results of his pea-plant experiments into four postulates, some of which are sometimes called “laws,” that describe the basis of dominant and recessive inheritance in diploid organisms. As you have learned, more complex extensions of Mendelism exist that do not exhibit the same F 2 phenotypic ratios (3:1). Nevertheless, these laws summarize the basics of classical genetics. Pairs of Unit Factors, or Genes Mendel proposed first that paired unit factors of heredity were transmitted faithfully from generation to generation by the dissociation and reassociation of paired factors during gametogenesis and fertilization, respectively. After he crossed peas with contrasting traits and found that the recessive trait resurfaced in the F 2 generation, Mendel deduced that hereditary factors must be inherited as discrete units. This finding contradicted the belief at that time that parental traits were blended in the offspring. Alleles Can Be Dominant or Recessive Mendel’s law of dominance states that in a heterozygote, one trait will conceal the presence of another trait for the same characteristic. Rather than both alleles contributing to a phenotype, the dominant allele will be expressed exclusively. The recessive allele will remain “latent” but will be transmitted to offspring by the same manner in which the dominant allele is transmitted. The recessive trait will only be expressed by offspring that have two copies of this allele ( Figure 12.15 ), and these offspring will breed true when self-crossed. Since Mendel’s experiments with pea plants, other researchers have found that the law of dominance does not always hold true. Instead, several different patterns of inheritance have been found to exist. Equal Segregation of Alleles Observing that true-breeding pea plants with contrasting traits gave rise to F 1 generations that all expressed the dominant trait and F 2 generations that expressed the dominant and recessive traits in a 3:1 ratio, Mendel proposed the law of segregation . This law states that paired unit factors (genes) must segregate equally into gametes such that offspring have an equal likelihood of inheriting either factor. For the F 2 generation of a monohybrid cross, the following three possible combinations of genotypes could result: homozygous dominant, heterozygous, or homozygous recessive. Because heterozygotes could arise from two different pathways (receiving one dominant and one recessive allele from either parent), and because heterozygotes and homozygous dominant individuals are phenotypically identical, the law supports Mendel’s observed 3:1 phenotypic ratio. The equal segregation of alleles is the reason we can apply the Punnett square to accurately predict the offspring of parents with known genotypes. The physical basis of Mendel’s law of segregation is the first division of meiosis, in which the homologous chromosomes with their different versions of each gene are segregated into daughter nuclei. The role of the meiotic segregation of chromosomes in sexual reproduction was not understood by the scientific community during Mendel’s lifetime. Independent Assortment Mendel’s law of independent assortment states that genes do not influence each other with regard to the sorting of alleles into gametes, and every possible combination of alleles for every gene is equally likely to occur. The independent assortment of genes can be illustrated by the dihybrid cross, a cross between two true-breeding parents that express different traits for two characteristics. Consider the characteristics of seed color and seed texture for two pea plants, one that has green, wrinkled seeds ( yyrr ) and another that has yellow, round seeds ( YYRR ). Because each parent is homozygous, the law of segregation indicates that the gametes for the green/wrinkled plant all are yr , and the gametes for the yellow/round plant are all YR . Therefore, the F 1 generation of offspring all are YyRr ( Figure 12.16 ). Visual Connection In pea plants, purple flowers (P) are dominant to white flowers (p) and yellow peas (Y) are dominant to green peas (y). What are the possible genotypes and phenotypes for a cross between PpYY and ppYy pea plants? How many squares do you need to do a Punnett square analysis of this cross? For the F2 generation, the law of segregation requires that each gamete receive either an R allele or an r allele along with either a Y allele or a y allele. The law of independent assortment states that a gamete into which an r allele sorted would be equally likely to contain either a Y allele or a y allele. Thus, there are four equally likely gametes that can be formed when the YyRr heterozygote is self-crossed, as follows: YR , Yr , yR , and yr . Arranging these gametes along the top and left of a 4 × 4 Punnett square ( Figure 12.16 ) gives us 16 equally likely genotypic combinations. From these genotypes, we infer a phenotypic ratio of 9 round/yellow:3 round/green:3 wrinkled/yellow:1 wrinkled/green ( Figure 12.16 ). These are the offspring ratios we would expect, assuming we performed the crosses with a large enough sample size. Because of independent assortment and dominance, the 9:3:3:1 dihybrid phenotypic ratio can be collapsed into two 3:1 ratios, characteristic of any monohybrid cross that follows a dominant and recessive pattern. Ignoring seed color and considering only seed texture in the above dihybrid cross, we would expect that three quarters of the F 2 generation offspring would be round, and one quarter would be wrinkled. Similarly, isolating only seed color, we would assume that three quarters of the F 2 offspring would be yellow and one quarter would be green. The sorting of alleles for texture and color are independent events, so we can apply the product rule. Therefore, the proportion of round and yellow F 2 offspring is expected to be (3/4) × (3/4) = 9/16, and the proportion of wrinkled and green offspring is expected to be (1/4) × (1/4) = 1/16. These proportions are identical to those obtained using a Punnett square. Round, green and wrinkled, yellow offspring can also be calculated using the product rule, as each of these genotypes includes one dominant and one recessive phenotype. Therefore, the proportion of each is calculated as (3/4) × (1/4) = 3/16. The law of independent assortment also indicates that a cross between yellow, wrinkled ( YYrr ) and green, round ( yyRR ) parents would yield the same F 1 and F 2 offspring as in the YYRR x yyrr cross. The physical basis for the law of independent assortment also lies in meiosis I, in which the different homologous pairs line up in random orientations. Each gamete can contain any combination of paternal and maternal chromosomes (and therefore the genes on them) because the orientation of tetrads on the metaphase plane is random. Forked-Line Method When more than two genes are being considered, the Punnett-square method becomes unwieldy. For instance, examining a cross involving four genes would require a 16 × 16 grid containing 256 boxes. It would be extremely cumbersome to manually enter each genotype. For more complex crosses, the forked-line and probability methods are preferred. To prepare a forked-line diagram for a cross between F 1 heterozygotes resulting from a cross between AABBCC and aabbcc parents, we first create rows equal to the number of genes being considered, and then segregate the alleles in each row on forked lines according to the probabilities for individual monohybrid crosses ( Figure 12.17 ). We then multiply the values along each forked path to obtain the F 2 offspring probabilities. Note that this process is a diagrammatic version of the product rule. The values along each forked pathway can be multiplied because each gene assorts independently. For a trihybrid cross, the F 2 phenotypic ratio is 27:9:9:9:3:3:3:1. Probability Method While the forked-line method is a diagrammatic approach to keeping track of probabilities in a cross, the probability method gives the proportions of offspring expected to exhibit each phenotype (or genotype) without the added visual assistance. Both methods make use of the product rule and consider the alleles for each gene separately. Earlier, we examined the phenotypic proportions for a trihybrid cross using the forked-line method; now we will use the probability method to examine the genotypic proportions for a cross with even more genes. For a trihybrid cross, writing out the forked-line method is tedious, albeit not as tedious as using the Punnett-square method. To fully demonstrate the power of the probability method, however, we can consider specific genetic calculations. For instance, for a tetrahybrid cross between individuals that are heterozygotes for all four genes, and in which all four genes are sorting independently and in a dominant and recessive pattern, what proportion of the offspring will be expected to be homozygous recessive for all four alleles? Rather than writing out every possible genotype, we can use the probability method. We know that for each gene, the fraction of homozygous recessive offspring will be 1/4. Therefore, multiplying this fraction for each of the four genes, (1/4) × (1/4) × (1/4) × (1/4), we determine that 1/256 of the offspring will be quadruply homozygous recessive. For the same tetrahybrid cross, what is the expected proportion of offspring that have the dominant phenotype at all four loci? We can answer this question using phenotypic proportions, but let’s do it the hard way—using genotypic proportions. The question asks for the proportion of offspring that are 1) homozygous dominant at A or heterozygous at A, and 2) homozygous at B or heterozygous at B , and so on. Noting the “or” and “and” in each circumstance makes clear where to apply the sum and product rules. The probability of a homozygous dominant at A is 1/4 and the probability of a heterozygote at A is 1/2. The probability of the homozygote or the heterozygote is 1/4 + 1/2 = 3/4 using the sum rule. The same probability can be obtained in the same way for each of the other genes, so that the probability of a dominant phenotype at A and B and C and D is, using the product rule, equal to 3/4 × 3/4 × 3/4 × 3/4, or 27/64. If you are ever unsure about how to combine probabilities, returning to the forked-line method should make it clear. Rules for Multihybrid Fertilization Predicting the genotypes and phenotypes of offspring from given crosses is the best way to test your knowledge of Mendelian genetics. Given a multihybrid cross that obeys independent assortment and follows a dominant and recessive pattern, several generalized rules exist; you can use these rules to check your results as you work through genetics calculations ( Table 12.5 ). To apply these rules, first you must determine n , the number of heterozygous gene pairs (the number of genes segregating two alleles each). For example, a cross between AaBb and AaBb heterozygotes has an n of 2. In contrast, a cross between AABb and AABb has an n of 1 because A is not heterozygous. General Rules for Multihybrid Crosses General Rule Number of Heterozygous Gene Pairs Number of different F 1 gametes 2 n Number of different F 2 genotypes 3 n Given dominant and recessive inheritance, the number of different F 2 phenotypes 2 n Table 12.5 Linked Genes Violate the Law of Independent Assortment Although all of Mendel’s pea characteristics behaved according to the law of independent assortment, we now know that some allele combinations are not inherited independently of each other. Genes that are located on separate non-homologous chromosomes will always sort independently. However, each chromosome contains hundreds or thousands of genes, organized linearly on chromosomes like beads on a string. The segregation of alleles into gametes can be influenced by linkage , in which genes that are located physically close to each other on the same chromosome are more likely to be inherited as a pair. However, because of the process of recombination, or “crossover,” it is possible for two genes on the same chromosome to behave independently, or as if they are not linked. To understand this, let’s consider the biological basis of gene linkage and recombination. Homologous chromosomes possess the same genes in the same linear order. The alleles may differ on homologous chromosome pairs, but the genes to which they correspond do not. In preparation for the first division of meiosis, homologous chromosomes replicate and synapse. Like genes on the homologs align with each other. At this stage, segments of homologous chromosomes exchange linear segments of genetic material ( Figure 12.18 ). This process is called recombination, or crossover, and it is a common genetic process. Because the genes are aligned during recombination, the gene order is not altered. Instead, the result of recombination is that maternal and paternal alleles are combined onto the same chromosome. Across a given chromosome, several recombination events may occur, causing extensive shuffling of alleles. When two genes are located in close proximity on the same chromosome, they are considered linked, and their alleles tend to be transmitted through meiosis together. To exemplify this, imagine a dihybrid cross involving flower color and plant height in which the genes are next to each other on the chromosome. If one homologous chromosome has alleles for tall plants and red flowers, and the other chromosome has genes for short plants and yellow flowers, then when the gametes are formed, the tall and red alleles will go together into a gamete and the short and yellow alleles will go into other gametes. These are called the parental genotypes because they have been inherited intact from the parents of the individual producing gametes. But unlike if the genes were on different chromosomes, there will be no gametes with tall and yellow alleles and no gametes with short and red alleles. If you create the Punnett square with these gametes, you will see that the classical Mendelian prediction of a 9:3:3:1 outcome of a dihybrid cross would not apply. As the distance between two genes increases, the probability of one or more crossovers between them increases, and the genes behave more like they are on separate chromosomes. Geneticists have used the proportion of recombinant gametes (the ones not like the parents) as a measure of how far apart genes are on a chromosome. Using this information, they have constructed elaborate maps of genes on chromosomes for well-studied organisms, including humans. Mendel’s seminal publication makes no mention of linkage, and many researchers have questioned whether he encountered linkage but chose not to publish those crosses out of concern that they would invalidate his independent assortment postulate. The garden pea has seven chromosomes, and some have suggested that his choice of seven characteristics was not a coincidence. However, even if the genes he examined were not located on separate chromosomes, it is possible that he simply did not observe linkage because of the extensive shuffling effects of recombination. Scientific Method Connection Testing the Hypothesis of Independent Assortment To better appreciate the amount of labor and ingenuity that went into Mendel’s experiments, proceed through one of Mendel’s dihybrid crosses. Question : What will be the offspring of a dihybrid cross? Background : Consider that pea plants mature in one growing season, and you have access to a large garden in which you can cultivate thousands of pea plants. There are several true-breeding plants with the following pairs of traits: tall plants with inflated pods, and dwarf plants with constricted pods. Before the plants have matured, you remove the pollen-producing organs from the tall/inflated plants in your crosses to prevent self-fertilization. Upon plant maturation, the plants are manually crossed by transferring pollen from the dwarf/constricted plants to the stigmata of the tall/inflated plants. Hypothesis : Both trait pairs will sort independently according to Mendelian laws. When the true-breeding parents are crossed, all of the F 1 offspring are tall and have inflated pods, which indicates that the tall and inflated traits are dominant over the dwarf and constricted traits, respectively. A self-cross of the F 1 heterozygotes results in 2,000 F 2 progeny. Test the hypothesis : Because each trait pair sorts independently, the ratios of tall:dwarf and inflated:constricted are each expected to be 3:1. The tall/dwarf trait pair is called T/t , and the inflated/constricted trait pair is designated I/i . Each member of the F 1 generation therefore has a genotype of TtIi . Construct a grid analogous to Figure 12.16 , in which you cross two TtIi individuals. Each individual can donate four combinations of two traits: TI , Ti , tI , or ti , meaning that there are 16 possibilities of offspring genotypes. Because the T and I alleles are dominant, any individual having one or two of those alleles will express the tall or inflated phenotypes, respectively, regardless if they also have a t or i allele. Only individuals that are tt or ii will express the dwarf and constricted alleles, respectively. As shown in Figure 12.19 , you predict that you will observe the following offspring proportions: tall/inflated:tall/constricted:dwarf/inflated:dwarf/constricted in a 9:3:3:1 ratio. Notice from the grid that when considering the tall/dwarf and inflated/constricted trait pairs in isolation, they are each inherited in 3:1 ratios. Test the hypothesis : You cross the dwarf and tall plants and then self-cross the offspring. For best results, this is repeated with hundreds or even thousands of pea plants. What special precautions should be taken in the crosses and in growing the plants? Analyze your data : You observe the following plant phenotypes in the F 2 generation: 2706 tall/inflated, 930 tall/constricted, 888 dwarf/inflated, and 300 dwarf/constricted. Reduce these findings to a ratio and determine if they are consistent with Mendelian laws. Form a conclusion : Were the results close to the expected 9:3:3:1 phenotypic ratio? Do the results support the prediction? What might be observed if far fewer plants were used, given that alleles segregate randomly into gametes? Try to imagine growing that many pea plants, and consider the potential for experimental error. For instance, what would happen if it was extremely windy one day? Epistasis Mendel’s studies in pea plants implied that the sum of an individual’s phenotype was controlled by genes (or as he called them, unit factors), such that every characteristic was distinctly and completely controlled by a single gene. In fact, single observable characteristics are almost always under the influence of multiple genes (each with two or more alleles) acting in unison. For example, at least eight genes contribute to eye color in humans. Link to Learning Eye color in humans is determined by multiple genes. Use the Eye Color Calculator to predict the eye color of children from parental eye color. In some cases, several genes can contribute to aspects of a common phenotype without their gene products ever directly interacting. In the case of organ development, for instance, genes may be expressed sequentially, with each gene adding to the complexity and specificity of the organ. Genes may function in complementary or synergistic fashions, such that two or more genes need to be expressed simultaneously to affect a phenotype. Genes may also oppose each other, with one gene modifying the expression of another. In epistasis , the interaction between genes is antagonistic, such that one gene masks or interferes with the expression of another. “Epistasis” is a word composed of Greek roots that mean “standing upon.” The alleles that are being masked or silenced are said to be hypostatic to the epistatic alleles that are doing the masking. Often the biochemical basis of epistasis is a gene pathway in which the expression of one gene is dependent on the function of a gene that precedes or follows it in the pathway. An example of epistasis is pigmentation in mice. The wild-type coat color, agouti ( AA ), is dominant to solid-colored fur ( aa ). However, a separate gene ( C ) is necessary for pigment production. A mouse with a recessive c allele at this locus is unable to produce pigment and is albino regardless of the allele present at locus A ( Figure 12.20 ). Therefore, the genotypes AAcc , Aacc , and aacc all produce the same albino phenotype. A cross between heterozygotes for both genes ( AaCc x AaCc ) would generate offspring with a phenotypic ratio of 9 agouti:3 solid color:4 albino ( Figure 12.20 ). In this case, the C gene is epistatic to the A gene. Epistasis can also occur when a dominant allele masks expression at a separate gene. Fruit color in summer squash is expressed in this way. Homozygous recessive expression of the W gene ( ww ) coupled with homozygous dominant or heterozygous expression of the Y gene ( YY or Yy ) generates yellow fruit, and the wwyy genotype produces green fruit. However, if a dominant copy of the W gene is present in the homozygous or heterozygous form, the summer squash will produce white fruit regardless of the Y alleles. A cross between white heterozygotes for both genes ( WwYy × WwYy ) would produce offspring with a phenotypic ratio of 12 white:3 yellow:1 green. Finally, epistasis can be reciprocal such that either gene, when present in the dominant (or recessive) form, expresses the same phenotype. In the shepherd’s purse plant ( Capsella bursa-pastoris ), the characteristic of seed shape is controlled by two genes in a dominant epistatic relationship. When the genes A and B are both homozygous recessive ( aabb ), the seeds are ovoid. If the dominant allele for either of these genes is present, the result is triangular seeds. That is, every possible genotype other than aabb results in triangular seeds, and a cross between heterozygotes for both genes ( AaBb x AaBb ) would yield offspring with a phenotypic ratio of 15 triangular:1 ovoid. As you work through genetics problems, keep in mind that any single characteristic that results in a phenotypic ratio that totals 16 is typical of a two-gene interaction. Recall the phenotypic inheritance pattern for Mendel’s dihybrid cross, which considered two non-interacting genes—9:3:3:1. Similarly, we would expect interacting gene pairs to also exhibit ratios expressed as 16 parts. Note that we are assuming the interacting genes are not linked; they are still assorting independently into gametes. Link to Learning For an excellent review of Mendel’s experiments and to perform your own crosses and identify patterns of inheritance, visit the Mendel’s Peas web lab.
american_government
Summary 2.1 The Pre-Revolutionary Period and the Roots of the American Political Tradition For many years the British colonists in North America had peacefully accepted rule by the king and Parliament. They were proud to be Englishmen. Much of their pride, however, stemmed from their belief that they were heirs to a tradition of limited government and royal acknowledgement of the rights of their subjects. Colonists’ pride in their English liberties gave way to dismay when they perceived that these liberties were being abused. People had come to regard life, liberty, and property not as gifts from the monarch but as natural rights no government could take away. A chain of incidents—the Proclamation of 1763, the trial of smugglers in courts without juries, the imposition of taxes without the colonists’ consent, and the attempted interference with self-government in the colonies—convinced many colonists that the social contract between the British government and its citizens had been broken. In 1776, the Second Continental Congress declared American independence from Great Britain. 2.2 The Articles of Confederation Fearful of creating a system so powerful that it might abuse its citizens, the men who drafted the Articles of Confederation deliberately sought to limit the powers of the national government. The states maintained the right to govern their residents, while the national government could declare war, coin money, and conduct foreign affairs but little else. Its inability to impose taxes, regulate commerce, or raise an army hindered its ability to defend the nation or pay its debts. A solution had to be found. 2.3 The Development of the Constitution Realizing that flaws in the Articles of Confederation could harm the new country and recognizing that the Articles could not easily be revised as originally intended, delegates from the states who met in Philadelphia from May through September 1787 set about drafting a new governing document. The United States that emerged from the Constitutional Convention in September was not a confederation, but it was a republic whose national government had been strengthened greatly. Congress had been transformed into a bicameral legislature with additional powers, and a national judicial system had been created. Most importantly, a federal system had been established with the power to govern the new country. To satisfy the concerns of those who feared an overly strong central government, the framers of the Constitution created a system with separation of powers and checks and balances. Although such measures satisfied many, concerns still lingered that the federal government remained too powerful. 2.4 The Ratification of the Constitution Anti-Federalists objected to the power the Constitution gave the federal government and the absence of a bill of rights to protect individual liberties. The Federalists countered that a strong government was necessary to lead the new nation and promised to add a bill of rights to the Constitution. The Federalist Papers , in particular, argued in favor of ratification and sought to convince people that the new government would not become tyrannical. Finally, in June 1788, New Hampshire became the ninth state to approve the Constitution, making it the law of the land. The large and prosperous states of Virginia and New York followed shortly thereafter, and the remaining states joined as well. 2.5 Constitutional Change One of the problems with the Articles of Confederation was the difficulty of changing it. To prevent this difficulty from recurring, the framers provided a method for amending the Constitution that required a two-thirds majority in both houses of Congress and in three-quarters of state legislatures to approve a change. The possibility of amending the Constitution helped ensure its ratification, although many feared the powerful federal government it created would deprive them of their rights. To allay their anxieties, the framers promised that a Bill of Rights safeguarding individual liberties would be added following ratification. These ten amendments were formally added to the document in 1791 and other amendments followed over the years. Among the most important were those ending slavery, granting citizenship to African Americans, and giving the right to vote to Americans regardless of race, color, or sex.
Chapter Outline 2.1 The Pre-Revolutionary Period and the Roots of the American Political Tradition 2.2 The Articles of Confederation 2.3 The Development of the Constitution 2.4 The Ratification of the Constitution 2.5 Constitutional Change Introduction The U.S. Constitution , see Figure 2.1 , is one of the world’s most enduring symbols of democracy. It is also the oldest, and shortest, written constitutions of the modern era still in existence. Its writing was by no means inevitable, however. Indeed, in many ways the Constitution was not the beginning but rather the culmination of American (and British) political thought about government power as well as a blueprint for the future. It is tempting to think of the framers of the Constitution as a group of like-minded men aligned in their lofty thinking regarding rights and freedoms. This assumption makes it hard to oppose constitutional principles in modern-day politics because people admire the longevity of the Constitution and like to consider its ideals above petty partisan politics. However, the Constitution was designed largely out of necessity following the failure of the first revolutionary government, and it featured a series of pragmatic compromises among its disparate stakeholders. It is therefore quite appropriate that more than 225 years later the U.S. government still requires compromise to function properly. How did the Constitution come to be written? What compromises were needed to ensure the ratification that made it into law? This chapter addresses these questions and also describes why the Constitution remains a living, changing document.
[ { "answer": { "ans_choice": 2, "ans_text": "C" }, "bloom": null, "hl_context": "The beliefs and attitudes that led to the call for independence had long been an important part of colonial life . <hl> Of all the political thinkers who influenced American beliefs about government , the most important is surely John Locke ( Figure 2.2 ) . <hl> The most significant contributions of Locke , a seventeenth-century English philosopher , were his ideas regarding the relationship between government and natural rights , which were believed to be God-given rights to life , liberty , and property .", "hl_sentences": "Of all the political thinkers who influenced American beliefs about government , the most important is surely John Locke ( Figure 2.2 ) .", "question": { "cloze_format": "British colonists in North America in the late seventeenth century were greatly influenced by the political thought of ________.", "normal_format": "British colonists in North America in the late seventeenth century were greatly influenced by whose political thought?", "question_choices": [ "King James II", "Thomas Jefferson", "John Locke", "James Madison" ], "question_id": "fs-id1166226382712", "question_text": "British colonists in North America in the late seventeenth century were greatly influenced by the political thought of ________." }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 2, "ans_text": "a bill of rights" }, "bloom": null, "hl_context": "So committed were the British to the protection of these natural rights that when the royal Stuart dynasty began to intrude upon them in the seventeenth century , Parliament removed King James II , already disliked because he was Roman Catholic , in the Glorious Revolution and invited his Protestant daughter and her husband to rule the nation . Before offering the throne to William and Mary , however , Parliament passed the English Bill of Rights in 1689 . <hl> A bill of rights is a list of the liberties and protections possessed by a nation ’ s citizens . <hl> The English Bill of Rights , heavily influenced by Locke ’ s ideas , enumerated the rights of English citizens and explicitly guaranteed rights to life , liberty , and property . This document would profoundly influence the U . S . Constitution and Bill of Rights .", "hl_sentences": "A bill of rights is a list of the liberties and protections possessed by a nation ’ s citizens .", "question": { "cloze_format": "The agreement that citizens will consent to be governed so long as government protects their natural rights is called ________.", "normal_format": "What is the agreement that citizens will consent to be governed so long as government protects their natural rights?", "question_choices": [ "the divine right of kings", "the social contract", "a bill of rights", "due process" ], "question_id": "fs-id1166226303386", "question_text": "The agreement that citizens will consent to be governed so long as government protects their natural rights is called ________." }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 2, "ans_text": "C" }, "bloom": null, "hl_context": "<hl> Congress was given great power , including the power to tax , maintain an army and a navy , and regulate trade and commerce . <hl> <hl> Congress had authority that the national government lacked under the Articles of Confederation . <hl> It could also coin and borrow money , grant patents and copyrights , declare war , and establish laws regulating naturalization and bankruptcy . While legislation could be proposed by either chamber of Congress , it had to pass both chambers by a majority vote before being sent to the president to be signed into law , and all bills to raise revenue had to begin in the House of Representatives . Only those men elected by the voters to represent them could impose taxes upon them . There would be no more taxation without representation . Others , however , feared that a strong national government might become too powerful and use its authority to oppress citizens and deprive them of their rights . They advocated a central government with sufficient authority to defend the nation but insisted that other powers be left to the states , which were believed to be better able to understand and protect the needs and interests of their residents . <hl> Such delegates approved the approach of the New Jersey Plan , which retained the unicameral Congress that had existed under the Articles of Confederation . <hl> It gave additional power to the national government , such as the power to regulate interstate and foreign commerce and to compel states to comply with laws passed by Congress . <hl> However , states still retained a lot of power , including power over the national government . <hl> <hl> Congress , for example , could not impose taxes without the consent of the states . <hl> Furthermore , the nation ’ s chief executive , appointed by the Congress , could be removed by Congress if state governors demanded it .", "hl_sentences": "Congress was given great power , including the power to tax , maintain an army and a navy , and regulate trade and commerce . Congress had authority that the national government lacked under the Articles of Confederation . Such delegates approved the approach of the New Jersey Plan , which retained the unicameral Congress that had existed under the Articles of Confederation . However , states still retained a lot of power , including power over the national government . Congress , for example , could not impose taxes without the consent of the states .", "question": { "cloze_format": "An important power that the national government lacked under the Articles of Confederation is that ___ .", "normal_format": "What important power did the national government lack under the Articles of Confederation?", "question_choices": [ "It could not coin money.", "It could not declare war.", "It could not impose taxes.", "It could not conduct foreign affairs." ], "question_id": "fs-id1166226348599", "question_text": "What important power did the national government lack under the Articles of Confederation?" }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 2, "ans_text": "C" }, "bloom": null, "hl_context": "After debating at length over whether the Virginia Plan or the New Jersey Plan provided the best model for the nation ’ s legislature , the framers of the Constitution had ultimately arrived at what is called the Great Compromise , suggested by Roger Sherman of Connecticut . <hl> Congress , it was decided , would consist of two chambers : the Senate and the House of Representatives . <hl> Each state , regardless of size , would have two senators , making for equal representation as in the New Jersey Plan . <hl> Representation in the House would be based on population . <hl> Senators were to be appointed by state legislatures , a variation on the Virginia Plan . Members of the House of Representatives would be popularly elected by the voters in each state . Elected members of the House would be limited to two years in office before having to seek reelection , and those appointed to the Senate by each state ’ s political elite would serve a term of six years .", "hl_sentences": "Congress , it was decided , would consist of two chambers : the Senate and the House of Representatives . Representation in the House would be based on population .", "question": { "cloze_format": "According to the Great Compromise, representation in Congress would be apportioned as ___ .", "normal_format": "According to the Great Compromise, how would representation in Congress be apportioned?", "question_choices": [ "Each state would have equal representation in both the House of Representatives and the Senate.", "Congress would be a unicameral legislature with each state receiving equal representation.", "Representation in the House of Representatives would be based on each state’s population and every state would have two senators.", "Representation in both the House of Representatives and the Senate would be based on a state’s population." ], "question_id": "fs-id1166227453471", "question_text": "According to the Great Compromise, how would representation in Congress be apportioned?" }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 3, "ans_text": "It was agreed that 60 percent of a state’s slave population would be counted for purposes of both representation and taxation." }, "bloom": null, "hl_context": "The Three-Fifths Compromise , illustrated in Figure 2.8 , resolved the impasse , although not in a manner that truly satisfied anyone . <hl> For purposes of Congressional apportionment , slaveholding states were allowed to count all their free population , including free African Americans and 60 percent ( three-fifths ) of their enslaved population . <hl> <hl> To mollify the north , the compromise also allowed counting 60 percent of a state ’ s slave population for federal taxation , although no such taxes were ever collected . <hl> Another compromise regarding the institution of slavery granted Congress the right to impose taxes on imports in exchange for a twenty-year prohibition on laws attempting to ban the importation of slaves to the United States , which would hurt the economy of southern states more than that of northern states . Because the southern states , especially South Carolina , had made it clear they would leave the convention if abolition were attempted , no serious effort was made by the framers to abolish slavery in the new nation , even though many delegates disapproved of the institution .", "hl_sentences": "For purposes of Congressional apportionment , slaveholding states were allowed to count all their free population , including free African Americans and 60 percent ( three-fifths ) of their enslaved population . To mollify the north , the compromise also allowed counting 60 percent of a state ’ s slave population for federal taxation , although no such taxes were ever collected .", "question": { "cloze_format": "The delegates to the Constitutional Convention resolved their disagreement regarding slavery because ___.", "normal_format": "How did the delegates to the Constitutional Convention resolve their disagreement regarding slavery?", "question_choices": [ "It was agreed that Congress would abolish slavery in 1850.", "It was agreed that a state’s slave population would be counted for purposes of representation but not for purposes of taxation.", "It was agreed that a state’s slave population would be counted for purposes of taxation but not for purposes of representation.", "It was agreed that 60 percent of a state’s slave population would be counted for purposes of both representation and taxation." ], "question_id": "fs-id1166227364942", "question_text": "How did the delegates to the Constitutional Convention resolve their disagreement regarding slavery?" }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 1, "ans_text": "To encourage New York to ratify the Constitution." }, "bloom": null, "hl_context": "<hl> The arguments of the Federalists were persuasive , but whether they actually succeeded in changing the minds of New Yorkers is unclear . <hl> Once Virginia ratified the Constitution on June 25 , 1788 , New York realized that it had little choice but to do so as well . If it did not ratify the Constitution , it would be the last large state that had not joined the union . Thus , on July 26 , 1788 , the majority of delegates to New York ’ s ratification convention voted to accept the Constitution . A year later , North Carolina became the twelfth state to approve . Alone and realizing it could not hope to survive on its own , Rhode Island became the last state to ratify , nearly two years after New York had done so .", "hl_sentences": "The arguments of the Federalists were persuasive , but whether they actually succeeded in changing the minds of New Yorkers is unclear .", "question": { "cloze_format": "The Federalist Papers were written ___.", "normal_format": "Why were The Federalist Papers written?", "question_choices": [ "To encourage states to oppose the Constitution.", "To encourage New York to ratify the Constitution.", "To oppose the admission of slaveholding states to the federal union.", "To encourage people to vote for George Washington as the nation’s first president." ], "question_id": "fs-id1166227571558", "question_text": "Why were The Federalist Papers written?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 3, "ans_text": "D" }, "bloom": null, "hl_context": "For those who worried that the president might indeed grow too ambitious or king-like , Hamilton , in Federalist No . 68 , provided assurance that placing the leadership of the country in the hands of one person was not dangerous . Electors from each state would select the president . Because these men would be members of a “ transient ” body called together only for the purpose of choosing the president and would meet in separate deliberations in each state , they would be free of corruption and beyond the influence of the “ heats and ferments ” of the voters . <hl> Indeed , Hamilton argued in Federalist No . <hl> <hl> 70 , instead of being afraid that the president would become a tyrant , Americans should realize that it was easier to control one person than it was to control many . <hl> <hl> Furthermore , one person could also act with an “ energy ” that Congress did not possess . <hl> Making decisions alone , the president could decide what actions should be taken faster than could Congress , whose deliberations , because of its size , were necessarily slow . At times , the “ decision , activity , secrecy , and dispatch ” of the chief executive might be necessary .", "hl_sentences": "Indeed , Hamilton argued in Federalist No . 70 , instead of being afraid that the president would become a tyrant , Americans should realize that it was easier to control one person than it was to control many . Furthermore , one person could also act with an “ energy ” that Congress did not possess .", "question": { "cloze_format": "The argument that Alexander Hamilton used to convince people that it was not dangerous to place power in the hands of one man was that ___.", "normal_format": "What argument did Alexander Hamilton use to convince people that it was not dangerous to place power in the hands of one man?", "question_choices": [ "That man would have to pass a religious test before he could become president; thus, citizens could be sure that he was of good character.", "One man could respond to crises more quickly than a group of men like Congress.", "It was easier to control the actions of one man than the actions of a group.", "both B and C" ], "question_id": "fs-id1166227586710", "question_text": "What argument did Alexander Hamilton use to convince people that it was not dangerous to place power in the hands of one man?" }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 1, "ans_text": "B" }, "bloom": null, "hl_context": "Madison followed the procedure outlined in Article V that says amendments can originate from one of two sources . First , they can be proposed by Congress . Then , they must be approved by a two-thirds majority in both the House and the Senate before being sent to the states for potential ratification . States have two ways to ratify or defeat a proposed amendment . First , if three-quarters of state legislatures vote to approve an amendment , it becomes part of the Constitution . <hl> Second , if three-quarters of state-ratifying conventions support the amendment , it is ratified . <hl> A second method of proposal of an amendment allows for the petitioning of Congress by the states : Upon receiving such petitions from two-thirds of the states , Congress must call a convention for the purpose of proposing amendments , which would then be forwarded to the states for ratification by the required three-quarters . All the current constitutional amendments were created using the first method of proposal ( via Congress ) . Having drafted nineteen proposed amendments , Madison submitted them to Congress . Only twelve were approved by two-thirds of both the Senate and the House of Representatives and sent to the states for ratification . Of these , only ten were accepted by three-quarters of the state legislatures . In 1791 , these first ten amendments were added to the Constitution and became known as the Bill of Rights .", "hl_sentences": "Second , if three-quarters of state-ratifying conventions support the amendment , it is ratified .", "question": { "cloze_format": "___ states must ratify an amendment before it becomes law.", "normal_format": "How many states must ratify an amendment before it becomes law?", "question_choices": [ "all", "three-fourths", "two-thirds", "one-half" ], "question_id": "fs-id1166226319583", "question_text": "How many states must ratify an amendment before it becomes law?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 0, "ans_text": "first ten amendments to the Constitution that protect individual freedoms" }, "bloom": null, "hl_context": "<hl> The Bill of Rights was intended to quiet the fears of Anti-Federalists that the Constitution did not adequately protect individual liberties and thus encourage their support of the new national government . <hl> <hl> Many of these first ten amendments were based on provisions of the English Bill of Rights and the Virginia Declaration of Rights . <hl> For example , the right to bear arms for protection ( Second Amendment ) , the right not to have to provide shelter and provision for soldiers in peacetime ( Third Amendment ) , the right to a trial by jury ( Sixth and Seventh Amendments ) , and protection from excessive fines and from cruel and unusual punishment ( Eighth Amendment ) are taken from the English Bill of Rights . The Fifth Amendment , which requires among other things that people cannot be deprived of their life , liberty , or property except by a legal proceeding , was also greatly influenced by English law as well as the protections granted to Virginians in the Virginia Declaration of Rights .", "hl_sentences": "The Bill of Rights was intended to quiet the fears of Anti-Federalists that the Constitution did not adequately protect individual liberties and thus encourage their support of the new national government . Many of these first ten amendments were based on provisions of the English Bill of Rights and the Virginia Declaration of Rights .", "question": { "cloze_format": "The Bill of Rights is the ___.", "normal_format": "What is the Bill of Rights?", "question_choices": [ "first ten amendments to the Constitution that protect individual freedoms", "powers given to Congress in Article I of the Constitution", "twenty-seven amendments added to the Constitution over the years", "document authored by Thomas Jefferson that details the rights of the citizens" ], "question_id": "fs-id1166226318625", "question_text": "What is the Bill of Rights?" }, "references_are_paraphrase": null } ]
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2.1 The Pre-Revolutionary Period and the Roots of the American Political Tradition Learning Objectives By the end of this section, you will be able to: Identify the origins of the core values in American political thought, including ideas regarding representational government Summarize Great Britain’s actions leading to the American Revolution American political ideas regarding liberty and self-government did not suddenly emerge full-blown at the moment the colonists declared their independence from Britain. The varied strands of what became the American republic had many roots, reaching far back in time and across the Atlantic Ocean to Europe. Indeed, it was not new ideas but old ones that led the colonists to revolt and form a new nation. POLITICAL THOUGHT IN THE AMERICAN COLONIES The beliefs and attitudes that led to the call for independence had long been an important part of colonial life. Of all the political thinkers who influenced American beliefs about government, the most important is surely John Locke ( Figure 2.2 ). The most significant contributions of Locke, a seventeenth-century English philosopher, were his ideas regarding the relationship between government and natural rights , which were believed to be God-given rights to life, liberty, and property. Locke was not the first Englishman to suggest that people had rights. The British government had recognized its duty to protect the lives, liberties, and property of English citizens long before the settling of its North American colonies. In 1215, King John signed Magna Carta —a promise to his subjects that he and future monarchs would refrain from certain actions that harmed, or had the potential to harm, the people of England. Prominent in Magna Carta’s many provisions are protections for life, liberty, and property. For example, one of the document’s most famous clauses promises, “No freemen shall be taken, imprisoned . . . or in any way destroyed . . . except by the lawful judgment of his peers or by the law of the land.” Although it took a long time for modern ideas regarding due process to form, this clause lays the foundation for the Fifth and Sixth Amendments to the U.S. Constitution. While Magna Carta was intended to grant protections only to the English barons who were in revolt against King John in 1215, by the time of the American Revolution, English subjects, both in England and in North America, had come to regard the document as a cornerstone of liberty for men of all stations—a right that had been recognized by King John I in 1215, but the people had actually possessed long before then. The rights protected by Magna Carta had been granted by the king, and, in theory, a future king or queen could take them away. The natural rights Locke described, however, had been granted by God and thus could never be abolished by human beings, even royal ones, or by the institutions they created. So committed were the British to the protection of these natural rights that when the royal Stuart dynasty began to intrude upon them in the seventeenth century, Parliament removed King James II, already disliked because he was Roman Catholic, in the Glorious Revolution and invited his Protestant daughter and her husband to rule the nation. Before offering the throne to William and Mary, however, Parliament passed the English Bill of Rights in 1689. A bill of rights is a list of the liberties and protections possessed by a nation’s citizens. The English Bill of Rights, heavily influenced by Locke’s ideas, enumerated the rights of English citizens and explicitly guaranteed rights to life, liberty, and property. This document would profoundly influence the U.S. Constitution and Bill of Rights. American colonists also shared Locke’s concept of property rights. According to Locke, anyone who invested labor in the commons —the land, forests, water, animals, and other parts of nature that were free for the taking—might take as much of these as needed, by cutting trees, for example, or building a fence around a field. The only restriction was that no one could take so much that others were deprived of their right to take from the commons as well. In the colonists’ eyes, all free white males should have the right to acquire property, and once it had been acquired, government had the duty to protect it. (The rights of women remained greatly limited for many more years.) Perhaps the most important of Locke’s ideas that influenced the British settlers of North America were those regarding the origins and purpose of government. Most Europeans of the time believed the institution of monarchy had been created by God, and kings and queens had been divinely appointed to rule. Locke, however, theorized that human beings, not God, had created government. People sacrificed a small portion of their freedom and consented to be ruled in exchange for the government’s protection of their lives, liberty, and property. Locke called this implicit agreement between a people and their government the social contract . Should government deprive people of their rights by abusing the power given to it, the contract was broken and the people were no longer bound by its terms. The people could thus withdraw their consent to obey and form another government for their protection. The belief that government should not deprive people of their liberties and should be restricted in its power over citizens’ lives was an important factor in the controversial decision by the American colonies to declare independence from England in 1776. For Locke, withdrawing consent to be ruled by an established government and forming a new one meant replacing one monarch with another. For those colonists intent on rebelling, however, it meant establishing a new nation and creating a new government, one that would be greatly limited in the power it could exercise over the people. The desire to limit the power of government is closely related to the belief that people should govern themselves. This core tenet of American political thought was rooted in a variety of traditions. First, the British government did allow for a degree of self-government. Laws were made by Parliament, and property-owning males were allowed to vote for representatives to Parliament. Thus, Americans were accustomed to the idea of representative government from the beginning. For instance, Virginia established its House of Burgesses in 1619. Upon their arrival in North America a year later, the English Separatists who settled the Plymouth Colony, commonly known as the Pilgrims, promptly authored the Mayflower Compact , an agreement to govern themselves according to the laws created by the male voters of the colony. 1 By the eighteenth century, all the colonies had established legislatures to which men were elected to make the laws for their fellow colonists. When American colonists felt that this longstanding tradition of representative self-government was threatened by the actions of Parliament and the King, the American Revolution began. THE AMERICAN REVOLUTION The American Revolution began when a small and vocal group of colonists became convinced the king and Parliament were abusing them and depriving them of their rights. By 1776, they had been living under the rule of the British government for more than a century, and England had long treated the thirteen colonies with a degree of benign neglect. Each colony had established its own legislature. Taxes imposed by England were low, and property ownership was more widespread than in England. People readily proclaimed their loyalty to the king. For the most part, American colonists were proud to be British citizens and had no desire to form an independent nation. All this began to change in 1763 when the Seven Years War between Great Britain and France came to an end, and Great Britain gained control of most of the French territory in North America. The colonists had fought on behalf of Britain, and many colonists expected that after the war they would be allowed to settle on land west of the Appalachian Mountains that had been taken from France. However, their hopes were not realized. Hoping to prevent conflict with Indian tribes in the Ohio Valley, Parliament passed the Proclamation of 1763 , which forbade the colonists to purchase land or settle west of the Appalachian Mountains. 2 To pay its debts from the war and maintain the troops it left behind to protect the colonies, the British government had to take new measures to raise revenue. Among the acts passed by Parliament were laws requiring American colonists to pay British merchants with gold and silver instead of paper currency and a mandate that suspected smugglers be tried in vice-admiralty courts, without jury trials. What angered the colonists most of all, however, was the imposition of direct taxes: taxes imposed on individuals instead of on transactions. Because the colonists had not consented to direct taxation, their primary objection was that it reduced their status as free men. The right of the people or their representatives to consent to taxation was enshrined in both Magna Carta and the English Bill of Rights. Taxes were imposed by the House of Commons, one of the two houses of the British Parliament. The North American colonists, however, were not allowed to elect representatives to that body. In their eyes, taxation by representatives they had not voted for was a denial of their rights. Members of the House of Commons and people living in England had difficulty understanding this argument. All British subjects had to obey the laws passed by Parliament, including the requirement to pay taxes. Those who were not allowed to vote, such as women and black people, were considered to have virtual representation in the British legislature; representatives elected by those who could vote made laws on behalf of those who could not. Many colonists, however, maintained that anything except direct representation was a violation of their rights as English subjects. The first such tax to draw the ire of colonists was the Stamp Act , passed in 1765, which required that almost all paper goods, such as diplomas, land deeds, contracts, and newspapers, have revenue stamps placed on them. The outcry was so great that the new tax was quickly withdrawn, but its repeal was soon followed by a series of other tax acts, such as the Townshend Acts (1767), which imposed taxes on many everyday objects such as glass, tea, and paint. The taxes imposed by the Townshend Acts were as poorly received by the colonists as the Stamp Act had been. The Massachusetts legislature sent a petition to the king asking for relief from the taxes and requested that other colonies join in a boycott of British manufactured goods. British officials threatened to suspend the legislatures of colonies that engaged in a boycott and, in response to a request for help from Boston’s customs collector, sent a warship to the city in 1768. A few months later, British troops arrived, and on the evening of March 5, 1770, an altercation erupted outside the customs house. Shots rang out as the soldiers fired into the crowd ( Figure 2.3 ). Several people were hit; three died immediately. Britain had taxed the colonists without their consent. Now, British soldiers had taken colonists’ lives. Following this event, later known as the Boston Massacre, resistance to British rule grew, especially in the colony of Massachusetts. In December 1773, a group of Boston men boarded a ship in Boston harbor and threw its cargo of tea, owned by the British East India Company, into the water to protest British policies, including the granting of a monopoly on tea to the British East India Company, which many colonial merchants resented. 3 This act of defiance became known as the Boston Tea Party . Today, many who do not agree with the positions of the Democratic or the Republican Party have organized themselves into an oppositional group dubbed the Tea Party ( Figure 2.4 ). In the early months of 1774, Parliament responded to this latest act of colonial defiance by passing a series of laws called the Coercive Acts , intended to punish Boston for leading resistance to British rule and to restore order in the colonies. These acts virtually abolished town meetings in Massachusetts and otherwise interfered with the colony’s ability to govern itself. This assault on Massachusetts and its economy enraged people throughout the colonies, and delegates from all the colonies except Georgia formed the First Continental Congress to create a unified opposition to Great Britain. Among other things, members of the institution developed a declaration of rights and grievances. In May 1775, delegates met again in the Second Continental Congress . By this time, war with Great Britain had already begun, following skirmishes between colonial militiamen and British troops at Lexington and Concord, Massachusetts. Congress drafted a Declaration of Causes explaining the colonies’ reasons for rebellion. On July 2, 1776, Congress declared American independence from Britain and two days later signed the Declaration of Independence . Drafted by Thomas Jefferson , the Declaration of Independence officially proclaimed the colonies’ separation from Britain. In it, Jefferson eloquently laid out the reasons for rebellion. God, he wrote, had given everyone the rights of life, liberty, and the pursuit of happiness. People had created governments to protect these rights and consented to be governed by them so long as government functioned as intended. However, “whenever any Form of Government becomes destructive of these ends, it is the Right of the People to alter or to abolish it, and to institute new Government.” Britain had deprived the colonists of their rights. The king had “establish[ed] . . . an absolute Tyranny over these States.” Just as their English forebears had removed King James II from the throne in 1689, the colonists now wished to establish a new rule. Jefferson then proceeded to list the many ways in which the British monarch had abused his power and failed in his duties to his subjects. The king, Jefferson charged, had taxed the colonists without the consent of their elected representatives, interfered with their trade, denied them the right to trial by jury, and deprived them of their right to self-government. Such intrusions on their rights could not be tolerated. With their signing of the Declaration of Independence ( Figure 2.5 ), the founders of the United States committed themselves to the creation of a new kind of government. Link to Learning Thomas Jefferson explains in the Declaration of Independence why many colonists felt the need to form a new nation. His evocation of the natural rights of man and his list of grievances against the king also served as the model for the Declaration of Sentiments that was written in 1848 in favor of giving women in the United States rights equal to those of men. View both documents and compare. 2.2 The Articles of Confederation Learning Objectives By the end of this section, you will be able to: Describe the steps taken during and after the American Revolution to create a government Identify the main features of the Articles of Confederation Describe the crises resulting from key features of the Articles of Confederation Waging a successful war against Great Britain required that the individual colonies, now sovereign states that often distrusted one another, form a unified nation with a central government capable of directing the country’s defense. Gaining recognition and aid from foreign nations would also be easier if the new United States had a national government able to borrow money and negotiate treaties. Accordingly, the Second Continental Congress called upon its delegates to create a new government strong enough to win the country’s independence but not so powerful that it would deprive people of the very liberties for which they were fighting. PUTTING A NEW GOVERNMENT IN PLACE The final draft of the Articles of Confederation , which formed the basis of the new nation’s government, was accepted by Congress in November 1777 and submitted to the states for ratification. It would not become the law of the land until all thirteen states had approved it. Within two years, all except Maryland had done so. Maryland argued that all territory west of the Appalachians, to which some states had laid claim, should instead be held by the national government as public land for the benefit of all the states. When the last of these states, Virginia, relinquished its land claims in early 1781, Maryland approved the Articles. 4 A few months later, the British surrendered. Americans wished their new government to be a republic , a regime in which the people, not a monarch, held power and elected representatives to govern according to the rule of law. Many, however, feared that a nation as large as the United States could not be ruled effectively as a republic. Many also worried that even a government of representatives elected by the people might become too powerful and overbearing. Thus, a confederation was created—an entity in which independent, self-governing states form a union for the purpose of acting together in areas such as defense. Fearful of replacing one oppressive national government with another, however, the framers of the Articles of Confederation created an alliance of sovereign states held together by a weak central government. Link to Learning View the Articles of Confederation at the National Archives. The timeline for drafting and ratifying the Articles of Confederation is available at the Library of Congress. Following the Declaration of Independence , each of the thirteen states had drafted and ratified a constitution providing for a republican form of government in which political power rested in the hands of the people, although the right to vote was limited to free (white) men, and the property requirements for voting differed among the states. Each state had a governor and an elected legislature. In the new nation, the states remained free to govern their residents as they wished. The central government had authority to act in only a few areas, such as national defense, in which the states were assumed to have a common interest (and would, indeed, have to supply militias). This arrangement was meant to prevent the national government from becoming too powerful or abusing the rights of individual citizens. In the careful balance between power for the national government and liberty for the states, the Articles of Confederation favored the states. Thus, powers given to the central government were severely limited. The Confederation Congress , formerly the Continental Congress , had the authority to exchange ambassadors and make treaties with foreign governments and Indian tribes, declare war, coin currency and borrow money, and settle disputes between states. Each state legislature appointed delegates to the Congress; these men could be recalled at any time. Regardless of its size or the number of delegates it chose to send, each state would have only one vote. Delegates could serve for no more than three consecutive years, lest a class of elite professional politicians develop. The nation would have no independent chief executive or judiciary. Nine votes were required before the central government could act, and the Articles of Confederation could be changed only by unanimous approval of all thirteen states. WHAT WENT WRONG WITH THE ARTICLES? The Articles of Confederation satisfied the desire of those in the new nation who wanted a weak central government with limited power. Ironically, however, their very success led to their undoing. It soon became apparent that, while they protected the sovereignty of the states, the Articles had created a central government too weak to function effectively. One of the biggest problems was that the national government had no power to impose taxes . To avoid any perception of “taxation without representation,” the Articles of Confederation allowed only state governments to levy taxes. To pay for its expenses, the national government had to request money from the states, which were required to provide funds in proportion to the value of the land within their borders. The states, however, were often negligent in this duty, and the national government was underfunded. Without money, it could not pay debts owed from the Revolution and had trouble conducting foreign affairs. For example, the inability of the U.S. government to raise sufficient funds to compensate colonists who had remained loyal to Great Britain for their property losses during and after the American Revolution was one of the reasons the British refused to evacuate the land west of the Appalachians. The new nation was also unable to protect American ships from attacks by the Barbary pirates. 5 Foreign governments were also, understandably, reluctant to loan money to a nation that might never repay it because it lacked the ability to tax its citizens. The fiscal problems of the central government meant that the currency it issued, called the Continental, was largely worthless and people were reluctant to use it. Furthermore, while the Articles of Confederation had given the national government the power to coin money, they had not prohibited the states from doing so as well. As a result, numerous state banks issued their own banknotes, which had the same problems as the Continental. People who were unfamiliar with the reputation of the banks that had issued the banknotes often refused to accept them as currency. This reluctance, together with the overwhelming debts of the states, crippled the young nation’s economy. The country’s economic woes were made worse by the fact that the central government also lacked the power to impose tariffs on foreign imports or regulate interstate commerce. Thus, it was unable to prevent British merchants from flooding the U.S. market with low-priced goods after the Revolution, and American producers suffered from the competition. Compounding the problem, states often imposed tariffs on items produced by other states and otherwise interfered with their neighbors’ trade. The national government also lacked the power to raise an army or navy. Fears of a standing army in the employ of a tyrannical government had led the writers of the Articles of Confederation to leave defense largely to the states. Although the central government could declare war and agree to peace, it had to depend upon the states to provide soldiers. If state governors chose not to honor the national government’s request, the country would lack an adequate defense. This was quite dangerous at a time when England and Spain still controlled large portions of North America ( Table 2.1 ). Problems with the Articles of Confederation Weakness of the Articles of Confederation Why Was This a Problem? The national government could not impose taxes on citizens. It could only request money from the states. Requests for money were usually not honored. As a result, the national government did not have money to pay for national defense or fulfill its other responsibilities. The national government could not regulate foreign trade or interstate commerce. The government could not prevent foreign countries from hurting American competitors by shipping inexpensive products to the United States. It could not prevent states from passing laws that interfered with domestic trade. The national government could not raise an army. It had to request the states to send men. State governments could choose not to honor Congress’s request for troops. This would make it hard to defend the nation. Each state had only one vote in Congress regardless of its size. Populous states were less well represented. The Articles could not be changed without a unanimous vote to do so. Problems with the Articles could not be easily fixed. There was no national judicial system. Judiciaries are important enforcers of national government power. Table 2.1 The Articles of Confederation suffered from many problems that could not be easily repaired. The biggest problem was the lack of power given to the national government. The weaknesses of the Articles of Confederation, already recognized by many, became apparent to all as a result of an uprising of Massachusetts farmers, led by Daniel Shays . Known as Shays’ Rebellion , the incident panicked the governor of Massachusetts, who called upon the national government for assistance. However, with no power to raise an army, the government had no troops at its disposal. After several months, Massachusetts crushed the uprising with the help of local militias and privately funded armies, but wealthy people were frightened by this display of unrest on the part of poor men and by similar incidents taking place in other states. 6 To find a solution and resolve problems related to commerce, members of Congress called for a revision of the Articles of Confederation. Milestone Shays’ Rebellion: Symbol of Disorder and Impetus to Act In the summer of 1786, farmers in western Massachusetts were heavily in debt, facing imprisonment and the loss of their lands. They owed taxes that had gone unpaid while they were away fighting the British during the Revolution. The Continental Congress had promised to pay them for their service, but the national government did not have sufficient money. Moreover, the farmers were unable to meet the onerous new tax burden Massachusetts imposed in order to pay its own debts from the Revolution. Led by Daniel Shays ( Figure 2.6 ), the heavily indebted farmers marched to a local courthouse demanding relief. Faced with the refusal of many Massachusetts militiamen to arrest the rebels, with whom they sympathized, Governor James Bowdoin called upon the national government for aid, but none was available. The uprising was finally brought to an end the following year by a privately funded militia after the protestors’ unsuccessful attempt to raid the Springfield Armory. Were Shays and his followers justified in their attacks on the government of Massachusetts? What rights might they have sought to protect? 2.3 The Development of the Constitution Learning Objectives By the end of this section, you will be able to: Identify the conflicts present and the compromises reached in drafting the Constitution Summarize the core features of the structure of U.S. government under the Constitution In 1786, Virginia and Maryland invited delegates from the other eleven states to meet in Annapolis, Maryland, for the purpose of revising the Articles of Confederation . However, only five states sent representatives. Because all thirteen states had to agree to any alteration of the Articles, the convention in Annapolis could not accomplish its goal. Two of the delegates, Alexander Hamilton and James Madison , requested that all states send delegates to a convention in Philadelphia the following year to attempt once again to revise the Articles of Confederation. All the states except Rhode Island chose delegates to send to the meeting, a total of seventy men in all, but many did not attend. Among those not in attendance were John Adams and Thomas Jefferson , both of whom were overseas representing the country as diplomats. Because the shortcomings of the Articles of Confederation proved impossible to overcome, the convention that met in Philadelphia in 1787 decided to create an entirely new government. POINTS OF CONTENTION Fifty-five delegates arrived in Philadelphia in May 1787 for the meeting that became known as the Constitutional Convention . Many wanted to strengthen the role and authority of the national government but feared creating a central government that was too powerful. They wished to preserve state autonomy, although not to a degree that prevented the states from working together collectively or made them entirely independent of the will of the national government. While seeking to protect the rights of individuals from government abuse, they nevertheless wished to create a society in which concerns for law and order did not give way in the face of demands for individual liberty. They wished to give political rights to all free men but also feared mob rule, which many felt would have been the result of Shays’ Rebellion had it succeeded. Delegates from small states did not want their interests pushed aside by delegations from more populous states like Virginia. And everyone was concerned about slavery. Representatives from southern states worried that delegates from states where it had been or was being abolished might try to outlaw the institution. Those who favored a nation free of the influence of slavery feared that southerners might attempt to make it a permanent part of American society. The only decision that all could agree on was the election of George Washington , the former commander of the Continental Army and hero of the American Revolution, as the president of the convention. The Question of Representation: Small States vs. Large States One of the first differences among the delegates to become clear was between those from large states, such as New York and Virginia, and those who represented small states, like Delaware. When discussing the structure of the government under the new constitution, the delegates from Virginia called for a bicameral legislature consisting of two houses. The number of a state’s representatives in each house was to be based on the state’s population. In each state, representatives in the lower house would be elected by popular vote. These representatives would then select their state’s representatives in the upper house from among candidates proposed by the state’s legislature. Once a representative’s term in the legislature had ended, the representative could not be reelected until an unspecified amount of time had passed. Delegates from small states objected to this Virginia Plan . Another proposal, the New Jersey Plan , called for a unicameral legislature with one house, in which each state would have one vote. Thus, smaller states would have the same power in the national legislature as larger states. However, the larger states argued that because they had more residents, they should be allotted more legislators to represent their interests ( Figure 2.7 ). Slavery and Freedom Another fundamental division separated the states. Following the Revolution, some of the northern states had either abolished slavery or instituted plans by which slaves would gradually be emancipated. Pennsylvania, for example, had passed the Act for the Gradual Abolition of Slavery in 1780. All people born in the state to enslaved mothers after the law’s passage would become indentured servants to be set free at age twenty-eight. In 1783, Massachusetts had freed all enslaved people within the state. Many Americans believed slavery was opposed to the ideals stated in the Declaration of Independence. Others felt it was inconsistent with the teachings of Christianity. Some feared for the safety of the country’s white population if the number of slaves and white Americans’ reliance on them increased. Although some southerners shared similar sentiments, none of the southern states had abolished slavery and none wanted the Constitution to interfere with the institution. In addition to supporting the agriculture of the South, slaves could be taxed as property and counted as population for purposes of a state’s representation in the government. Federal Supremacy vs. State Sovereignty Perhaps the greatest division among the states split those who favored a strong national government and those who favored limiting its powers and allowing states to govern themselves in most matters. Supporters of a strong central government argued that it was necessary for the survival and efficient functioning of the new nation. Without the authority to maintain and command an army and navy, the nation could not defend itself at a time when European powers still maintained formidable empires in North America. Without the power to tax and regulate trade, the government would not have enough money to maintain the nation’s defense, protect American farmers and manufacturers from foreign competition, create the infrastructure necessary for interstate commerce and communications, maintain foreign embassies, or pay federal judges and other government officials. Furthermore, other countries would be reluctant to loan money to the United States if the federal government lacked the ability to impose taxes in order to repay its debts. Besides giving more power to populous states, the Virginia Plan also favored a strong national government that would legislate for the states in many areas and would have the power to veto laws passed by state legislatures. Others, however, feared that a strong national government might become too powerful and use its authority to oppress citizens and deprive them of their rights. They advocated a central government with sufficient authority to defend the nation but insisted that other powers be left to the states, which were believed to be better able to understand and protect the needs and interests of their residents. Such delegates approved the approach of the New Jersey Plan, which retained the unicameral Congress that had existed under the Articles of Confederation. It gave additional power to the national government, such as the power to regulate interstate and foreign commerce and to compel states to comply with laws passed by Congress. However, states still retained a lot of power, including power over the national government. Congress, for example, could not impose taxes without the consent of the states. Furthermore, the nation’s chief executive, appointed by the Congress, could be removed by Congress if state governors demanded it. Individual Liberty vs. Social Stability The belief that the king and Parliament had deprived colonists of their liberties had led to the Revolution, and many feared the government of the United States might one day attempt to do the same. They wanted and expected their new government to guarantee the rights of life, liberty, and property. Others believed it was more important for the national government to maintain order, and this might require it to limit personal liberty at times. All Americans, however, desired that the government not intrude upon people’s rights to life, liberty, and property without reason. COMPROMISE AND THE CONSTITUTIONAL DESIGN OF AMERICAN GOVERNMENT Beginning in May 1787 and throughout the long, hot Philadelphia summer, the delegations from twelve states discussed, debated, and finally—after compromising many times—by September had worked out a new blueprint for the nation. The document they created, the U.S. Constitution, was an ingenious instrument that allayed fears of a too-powerful central government and solved the problems that had beleaguered the national government under the Articles of Confederation. For the most part, it also resolved the conflicts between small and large states, northern and southern states, and those who favored a strong federal government and those who argued for state sovereignty. Link to Learning The closest thing to minutes of the Constitutional Convention is the collection of James Madison’s letters and notes about the proceedings in Philadelphia. Several such letters and notes may be found at the Library of Congress’s American Memory project. The Great Compromise The Constitution consists of a preamble and seven articles. The first three articles divide the national government into three branches—Congress, the executive branch, and the federal judiciary—and describe the powers and responsibilities of each. In Article I, ten sections describe the structure of Congress , the basis for representation and the requirements for serving in Congress, the length of Congressional terms, and the powers of Congress. The national legislature created by the article reflects the compromises reached by the delegates regarding such issues as representation, slavery, and national power. After debating at length over whether the Virginia Plan or the New Jersey Plan provided the best model for the nation’s legislature, the framers of the Constitution had ultimately arrived at what is called the Great Compromise , suggested by Roger Sherman of Connecticut. Congress, it was decided, would consist of two chambers: the Senate and the House of Representatives. Each state, regardless of size, would have two senators, making for equal representation as in the New Jersey Plan. Representation in the House would be based on population. Senators were to be appointed by state legislatures, a variation on the Virginia Plan. Members of the House of Representatives would be popularly elected by the voters in each state. Elected members of the House would be limited to two years in office before having to seek reelection, and those appointed to the Senate by each state’s political elite would serve a term of six years. Congress was given great power, including the power to tax, maintain an army and a navy, and regulate trade and commerce. Congress had authority that the national government lacked under the Articles of Confederation. It could also coin and borrow money, grant patents and copyrights, declare war, and establish laws regulating naturalization and bankruptcy. While legislation could be proposed by either chamber of Congress, it had to pass both chambers by a majority vote before being sent to the president to be signed into law, and all bills to raise revenue had to begin in the House of Representatives. Only those men elected by the voters to represent them could impose taxes upon them. There would be no more taxation without representation. The Three-Fifths Compromise and the Debates over Slavery The Great Compromise that determined the structure of Congress soon led to another debate, however. When states took a census of their population for the purpose of allotting House representatives, should slaves be counted? Southern states were adamant that they should be, while delegates from northern states were vehemently opposed, arguing that representatives from southern states could not represent the interests of enslaved people. If slaves were not counted, however, southern states would have far fewer representatives in the House than northern states did. For example, if South Carolina were allotted representatives based solely on its free population, it would receive only half the number it would have received if slaves, who made up approximately 43 percent of the population, were included. 7 The Three-Fifths Compromise , illustrated in Figure 2.8 , resolved the impasse, although not in a manner that truly satisfied anyone. For purposes of Congressional apportionment, slaveholding states were allowed to count all their free population, including free African Americans and 60 percent (three-fifths) of their enslaved population. To mollify the north, the compromise also allowed counting 60 percent of a state’s slave population for federal taxation, although no such taxes were ever collected. Another compromise regarding the institution of slavery granted Congress the right to impose taxes on imports in exchange for a twenty-year prohibition on laws attempting to ban the importation of slaves to the United States, which would hurt the economy of southern states more than that of northern states. Because the southern states, especially South Carolina, had made it clear they would leave the convention if abolition were attempted, no serious effort was made by the framers to abolish slavery in the new nation, even though many delegates disapproved of the institution. Indeed, the Constitution contained two protections for slavery. Article I postponed the abolition of the foreign slave trade until 1808, and in the interim, those in slaveholding states were allowed to import as many slaves as they wished. 8 Furthermore, the Constitution placed no restrictions on the domestic slave trade, so residents of one state could still sell enslaved people to other states. Article IV of the Constitution—which, among other things, required states to return fugitives to the states where they had been charged with crimes—also prevented slaves from gaining their freedom by escaping to states where slavery had been abolished. Clause 3 of Article IV (known as the fugitive slave clause) allowed slave owners to reclaim their human property in the states where slaves had fled. 9 Separation of Powers and Checks and Balances Although debates over slavery and representation in Congress occupied many at the convention, the chief concern was the challenge of increasing the authority of the national government while ensuring that it did not become too powerful. The framers resolved this problem through a separation of powers , dividing the national government into three separate branches and assigning different responsibilities to each one, as shown in Figure 2.9 . They also created a system of checks and balances by giving each of three branches of government the power to restrict the actions of the others, thus requiring them to work together. Congress was given the power to make laws, but the executive branch, consisting of the president and the vice president, and the federal judiciary, notably the Supreme Court, were created to, respectively, enforce laws and try cases arising under federal law. Neither of these branches had existed under the Articles of Confederation. Thus, Congress can pass laws, but its power to do so can be checked by the president, who can veto potential legislation so that it cannot become a law. Later, in the 1803 case of Marbury v. Madison , the U.S. Supreme Court established its own authority to rule on the constitutionality of laws, a process called judicial review. Other examples of checks and balances include the ability of Congress to limit the president’s veto. Should the president veto a bill passed by both houses of Congress, the bill is returned to Congress to be voted on again. If the bill passes both the House of Representatives and the Senate with a two-thirds vote in its favor, it becomes law even though the president has refused to sign it. Congress is also able to limit the president’s power as commander-in-chief of the armed forces by refusing to declare war or provide funds for the military. To date, the Congress has never refused a president’s request for a declaration of war. The president must also seek the advice and consent of the Senate before appointing members of the Supreme Court and ambassadors, and the Senate must approve the ratification of all treaties signed by the president. Congress may even remove the president from office. To do this, both chambers of Congress must work together. The House of Representatives impeaches the president by bringing formal charges against him or her, and the Senate tries the case in a proceeding overseen by the Chief Justice of the Supreme Court. The president is removed from office if found guilty. According to political scientist Richard Neustadt, the system of separation of powers and checks and balances does not so much allow one part of government to control another as it encourages the branches to cooperate. Instead of a true separation of powers, the Constitutional Convention “created a government of separated institutions sharing powers.” 10 For example, knowing the president can veto a law he or she disapproves, Congress will attempt to draft a bill that addresses the president’s concerns before sending it to the White House for signing. Similarly, knowing that Congress can override a veto, the president will use this power sparingly. Federal Power vs. State Power The strongest guarantee that the power of the national government would be restricted and the states would retain a degree of sovereignty was the framers’ creation of a federal system of government. In a federal system , power is divided between the federal (or national) government and the state governments. Great or explicit powers, called enumerated powers , were granted to the federal government to declare war, impose taxes, coin and regulate currency, regulate foreign and interstate commerce, raise and maintain an army and a navy, maintain a post office, make treaties with foreign nations and with Native American tribes, and make laws regulating the naturalization of immigrants. All powers not expressly given to the national government, however, were intended to be exercised by the states. These powers are known as reserved powers ( Figure 2.10 ). Thus, states remained free to pass laws regarding such things as intrastate commerce (commerce within the borders of a state) and marriage. Some powers, such as the right to levy taxes, were given to both the state and federal governments. Both the states and the federal government have a chief executive to enforce the laws (a governor and the president, respectively) and a system of courts. Although the states retained a considerable degree of sovereignty, the supremacy clause in Article VI of the Constitution proclaimed that the Constitution, laws passed by Congress, and treaties made by the federal government were “the supreme Law of the Land.” In the event of a conflict between the states and the national government, the national government would triumph. Furthermore, although the federal government was to be limited to those powers enumerated in the Constitution, Article I provided for the expansion of Congressional powers if needed. The “necessary and proper” clause of Article I provides that Congress may “make all Laws which shall be necessary and proper for carrying into Execution the foregoing [enumerated] Powers, and all other Powers vested by this Constitution in the Government of the United States, or in any Department or Officer thereof.” The Constitution also gave the federal government control over all “Territory or other Property belonging to the United States.” This would prove problematic when, as the United States expanded westward and population growth led to an increase in the power of the northern states in Congress, the federal government sought to restrict the expansion of slavery into newly acquired territories. Link to Learning A growing number of institutes and study centers focus on the Constitution and the founding of the republic. Examples such as the Institute for the American Constitutional Heritage and the Bill of Rights Institute have informative public websites with documents and videos. Another example is the National Constitution Center that also holds programs related to aspects of the enduring U.S. Constitution. 2.4 The Ratification of the Constitution Learning Objectives By the end of this section, you will be able to: Identify the steps required to ratify the Constitution Describe arguments the framers raised in support of a strong national government and counterpoints raised by the Anti-Federalists On September 17, 1787, the delegates to the Constitutional Convention in Philadelphia voted to approve the document they had drafted over the course of many months. Some did not support it, but the majority did. Before it could become the law of the land, however, the Constitution faced another hurdle. It had to be ratified by the states. THE RATIFICATION PROCESS Article VII, the final article of the Constitution, required that before the Constitution could become law and a new government could form, the document had to be ratified by nine of the thirteen states. Eleven days after the delegates at the Philadelphia convention approved it, copies of the Constitution were sent to each of the states, which were to hold ratifying conventions to either accept or reject it. This approach to ratification was an unusual one. Since the authority inherent in the Articles of Confederation and the Confederation Congress had rested on the consent of the states, changes to the nation’s government should also have been ratified by the state legislatures. Instead, by calling upon state legislatures to hold ratification conventions to approve the Constitution, the framers avoided asking the legislators to approve a document that would require them to give up a degree of their own power. The men attending the ratification conventions would be delegates elected by their neighbors to represent their interests. They were not being asked to relinquish their power; in fact, they were being asked to place limits upon the power of their state legislators, whom they may not have elected in the first place. Finally, because the new nation was to be a republic in which power was held by the people through their elected representatives, it was considered appropriate to leave the ultimate acceptance or rejection of the Constitution to the nation’s citizens. If convention delegates, who were chosen by popular vote, approved it, then the new government could rightly claim that it ruled with the consent of the people. The greatest sticking point when it came to ratification, as it had been at the Constitutional Convention itself, was the relative power of the state and federal governments. The framers of the Constitution believed that without the ability to maintain and command an army and navy, impose taxes, and force the states to comply with laws passed by Congress, the young nation would not survive for very long. But many people resisted increasing the powers of the national government at the expense of the states. Virginia’s Patrick Henry , for example, feared that the newly created office of president would place excessive power in the hands of one man. He also disapproved of the federal government’s new ability to tax its citizens. This right, Henry believed, should remain with the states. Other delegates, such as Edmund Randolph of Virginia, disapproved of the Constitution because it created a new federal judicial system. Their fear was that the federal courts would be too far away from where those who were tried lived. State courts were located closer to the homes of both plaintiffs and defendants, and it was believed that judges and juries in state courts could better understand the actions of those who appeared before them. In response to these fears, the federal government created federal courts in each of the states as well as in Maine, which was then part of Massachusetts, and Kentucky, which was part of Virginia. 11 Perhaps the greatest source of dissatisfaction with the Constitution was that it did not guarantee protection of individual liberties. State governments had given jury trials to residents charged with violating the law and allowed their residents to possess weapons for their protection. Some had practiced religious tolerance as well. The Constitution, however, did not contain reassurances that the federal government would do so. Although it provided for habeas corpus and prohibited both a religious test for holding office and granting noble titles, some citizens feared the loss of their traditional rights and the violation of their liberties. This led many of the Constitution’s opponents to call for a bill of rights and the refusal to ratify the document without one. The lack of a bill of rights was especially problematic in Virginia, as the Virginia Declaration of Rights was the most extensive rights-granting document among the states. The promise that a bill of rights would be drafted for the Constitution persuaded delegates in many states to support ratification. 12 Insider Perspective Thomas Jefferson on the Bill of Rights John Adams and Thomas Jefferson carried on a lively correspondence regarding the ratification of the Constitution. In the following excerpt (reproduced as written) from a letter dated March 15, 1789, after the Constitution had been ratified by nine states but before it had been approved by all thirteen, Jefferson reiterates his previously expressed concerns that a bill of rights to protect citizens’ freedoms was necessary and should be added to the Constitution: “In the arguments in favor of a declaration of rights, . . . I am happy to find that on the whole you are a friend to this amendment. The Declaration of rights is like all other human blessings alloyed with some inconveniences, and not accomplishing fully it’s object. But the good in this instance vastly overweighs the evil. . . . This instrument [the Constitution] forms us into one state as to certain objects, and gives us a legislative & executive body for these objects. It should therefore guard us against their abuses of power. . . . Experience proves the inefficacy of a bill of rights. True. But tho it is not absolutely efficacious under all circumstances, it is of great potency always, and rarely inefficacious. . . . There is a remarkeable difference between the . . . Inconveniences which attend a Declaration of rights, & those which attend the want of it. . . . The inconveniences of the want of a Declaration are permanent, afflicting & irreparable: they are in constant progression from bad to worse.” 13 What were some of the inconveniences of not having a bill of rights that Jefferson mentioned? Why did he decide in favor of having one? It was clear how some states would vote. Smaller states, like Delaware, favored the Constitution. Equal representation in the Senate would give them a degree of equality with the larger states, and a strong national government with an army at its command would be better able to defend them than their state militias could. Larger states, however, had significant power to lose. They did not believe they needed the federal government to defend them and disliked the prospect of having to provide tax money to support the new government. Thus, from the very beginning, the supporters of the Constitution feared that New York, Massachusetts, Pennsylvania, and Virginia would refuse to ratify it. That would mean all nine of the remaining states would have to, and Rhode Island, the smallest state, was unlikely to do so. It had not even sent delegates to the convention in Philadelphia. And even if it joined the other states in ratifying the document and the requisite nine votes were cast, the new nation would not be secure without its largest, wealthiest, and most populous states as members of the union. THE RATIFICATION CAMPAIGN On the question of ratification, citizens quickly separated into two groups: Federalists and Anti-Federalists. The Federalists supported it. They tended to be among the elite members of society—wealthy and well-educated landowners, businessmen, and former military commanders who believed a strong government would be better for both national defense and economic growth. A national currency, which the federal government had the power to create, would ease business transactions. The ability of the federal government to regulate trade and place tariffs on imports would protect merchants from foreign competition. Furthermore, the power to collect taxes would allow the national government to fund internal improvements like roads, which would also help businessmen. Support for the Federalists was especially strong in New England. Opponents of ratification were called Anti-Federalists . Anti-Federalists feared the power of the national government and believed state legislatures, with which they had more contact, could better protect their freedoms. Although some Anti-Federalists, like Patrick Henry , were wealthy, most distrusted the elite and believed a strong federal government would favor the rich over those of “the middling sort.” This was certainly the fear of Melancton Smith , a New York merchant and landowner, who believed that power should rest in the hands of small, landowning farmers of average wealth who “are more temperate, of better morals and less ambitious than the great.” 14 Even members of the social elite, like Henry, feared that the centralization of power would lead to the creation of a political aristocracy, to the detriment of state sovereignty and individual liberty. Related to these concerns were fears that the strong central government Federalists advocated for would levy taxes on farmers and planters, who lacked the hard currency needed to pay them. Many also believed Congress would impose tariffs on foreign imports that would make American agricultural products less welcome in Europe and in European colonies in the western hemisphere. For these reasons, Anti-Federalist sentiment was especially strong in the South. Some Anti-Federalists also believed that the large federal republic that the Constitution would create could not work as intended. Americans had long believed that virtue was necessary in a nation where people governed themselves (i.e., the ability to put self-interest and petty concerns aside for the good of the larger community). In small republics, similarities among members of the community would naturally lead them to the same positions and make it easier for those in power to understand the needs of their neighbors. In a larger republic, one that encompassed nearly the entire Eastern Seaboard and ran west to the Appalachian Mountains, people would lack such a strong commonality of interests. 15 Likewise, Anti-Federalists argued, the diversity of religion tolerated by the Constitution would prevent the formation of a political community with shared values and interests. The Constitution contained no provisions for government support of churches or of religious education, and Article VI explicitly forbade the use of religious tests to determine eligibility for public office. This caused many, like Henry Abbot of North Carolina, to fear that government would be placed in the hands of “pagans . . . and Mahometans [Muslims].” 16 It is difficult to determine how many people were Federalists and how many were Anti-Federalists in 1787. The Federalists won the day, but they may not have been in the majority. First, the Federalist position tended to win support among businessmen, large farmers, and, in the South, plantation owners. These people tended to live along the Eastern Seaboard. In 1787, most of the states were divided into voting districts in a manner that gave more votes to the eastern part of the state than to the western part. 17 Thus, in some states, like Virginia and South Carolina, small farmers who may have favored the Anti-Federalist position were unable to elect as many delegates to state ratification conventions as those who lived in the east. Small settlements may also have lacked the funds to send delegates to the convention. 18 In all the states, educated men authored pamphlets and published essays and cartoons arguing either for or against ratification ( Figure 2.11 ). Although many writers supported each position, it is the Federalist essays that are now best known. The arguments these authors put forth, along with explicit guarantees that amendments would be added to protect individual liberties, helped to sway delegates to ratification conventions in many states. For obvious reasons, smaller, less populous states favored the Constitution and the protection of a strong federal government. As shown in Figure 2.12 , Delaware and New Jersey ratified the document within a few months after it was sent to them for approval in 1787. Connecticut ratified it early in 1788. Some of the larger states, such as Pennsylvania and Massachusetts, also voted in favor of the new government. New Hampshire became the ninth state to ratify the Constitution in the summer of 1788. Although the Constitution went into effect following ratification by New Hampshire, four states still remained outside the newly formed union. Two were the wealthy, populous states of Virginia and New York. In Virginia, James Madison’s active support and the intercession of George Washington, who wrote letters to the convention, changed the minds of many. Some who had initially opposed the Constitution, such as Edmund Randolph, were persuaded that the creation of a strong union was necessary for the country’s survival and changed their position. Other Virginia delegates were swayed by the promise that a bill of rights similar to the Virginia Declaration of Rights would be added after the Constitution was ratified. On June 25, 1788, Virginia became the tenth state to grant its approval. The approval of New York was the last major hurdle. Facing considerable opposition to the Constitution in that state, Alexander Hamilton , James Madison , and John Jay wrote a series of essays, beginning in 1787, arguing for a strong federal government and support of the Constitution ( Figure 2.13 ). Later compiled as The Federalist and now known as The Federalist Papers , these eighty-five essays were originally published in newspapers in New York and other states under the name of Publius, a supporter of the Roman Republic. The essays addressed a variety of issues that troubled citizens. For example, in Federalist No. 51, attributed to James Madison ( Figure 2.14 ), the author assured readers they did not need to fear that the national government would grow too powerful. The federal system, in which power was divided between the national and state governments, and the division of authority within the federal government into separate branches would prevent any one part of the government from becoming too strong. Furthermore, tyranny could not arise in a government in which “the legislature necessarily predominates.” Finally, the desire of office holders in each branch of government to exercise the powers given to them, described as “personal motives,” would encourage them to limit any attempt by the other branches to overstep their authority. According to Madison , “Ambition must be made to counteract ambition.” Other essays countered different criticisms made of the Constitution and echoed the argument in favor of a strong national government. In Federalist No. 35 , for example, Hamilton ( Figure 2.14 ) argued that people’s interests could in fact be represented by men who were not their neighbors. Indeed, Hamilton asked rhetorically, would American citizens best be served by a representative “whose observation does not travel beyond the circle of his neighbors and his acquaintances” or by someone with more extensive knowledge of the world? To those who argued that a merchant and land-owning elite would come to dominate Congress, Hamilton countered that the majority of men currently sitting in New York’s state senate and assembly were landowners of moderate wealth and that artisans usually chose merchants, “their natural patron[s] and friend[s],” to represent them. An aristocracy would not arise, and if it did, its members would have been chosen by lesser men. Similarly, Jay reminded New Yorkers in Federalist No. 2 that union had been the goal of Americans since the time of the Revolution. A desire for union was natural among people of such “similar sentiments” who “were united to each other by the strongest ties,” and the government proposed by the Constitution was the best means of achieving that union. Objections that an elite group of wealthy and educated bankers, businessmen, and large landowners would come to dominate the nation’s politics were also addressed by Madison in Federalist No. 10 . Americans need not fear the power of factions or special interests, he argued, for the republic was too big and the interests of its people too diverse to allow the development of large, powerful political parties. Likewise, elected representatives, who were expected to “possess the most attractive merit,” would protect the government from being controlled by “an unjust and interested [biased in favor of their own interests] majority.” For those who worried that the president might indeed grow too ambitious or king-like, Hamilton, in Federalist No. 68 , provided assurance that placing the leadership of the country in the hands of one person was not dangerous. Electors from each state would select the president. Because these men would be members of a “transient” body called together only for the purpose of choosing the president and would meet in separate deliberations in each state, they would be free of corruption and beyond the influence of the “heats and ferments” of the voters. Indeed, Hamilton argued in Federalist No. 70 , instead of being afraid that the president would become a tyrant, Americans should realize that it was easier to control one person than it was to control many. Furthermore, one person could also act with an “energy” that Congress did not possess. Making decisions alone, the president could decide what actions should be taken faster than could Congress, whose deliberations, because of its size, were necessarily slow. At times, the “decision, activity, secrecy, and dispatch” of the chief executive might be necessary. Link to Learning The Library of Congress has The Federalist Papers on their website. The Anti-Federalists also produced a body of writings, less extensive than The Federalists Papers , which argued against the ratification of the Constitution. However, these were not written by one small group of men as The Federalist Papers had been. A collection of the writings that are unofficially called The Anti-Federalist Papers is also available online. The arguments of the Federalists were persuasive, but whether they actually succeeded in changing the minds of New Yorkers is unclear. Once Virginia ratified the Constitution on June 25, 1788, New York realized that it had little choice but to do so as well. If it did not ratify the Constitution, it would be the last large state that had not joined the union. Thus, on July 26, 1788, the majority of delegates to New York’s ratification convention voted to accept the Constitution. A year later, North Carolina became the twelfth state to approve. Alone and realizing it could not hope to survive on its own, Rhode Island became the last state to ratify, nearly two years after New York had done so. Finding a Middle Ground Term Limits One of the objections raised to the Constitution’s new government was that it did not set term limits for members of Congress or the president. Those who opposed a strong central government argued that this failure could allow a handful of powerful men to gain control of the nation and rule it for as long as they wished. Although the framers did not anticipate the idea of career politicians, those who supported the Constitution argued that reelecting the president and reappointing senators by state legislatures would create a body of experienced men who could better guide the country through crises. A president who did not prove to be a good leader would be voted out of office instead of being reelected. In fact, presidents long followed George Washington’s example and limited themselves to two terms. Only in 1951, after Franklin Roosevelt had been elected four times, was the Twenty-Second Amendment passed to restrict the presidency to two terms. Are term limits a good idea? Should they have originally been included in the Constitution? Why or why not? Are there times when term limits might not be good? 2.5 Constitutional Change Learning Objectives By the end of this section, you will be able to: Describe how the Constitution can be formally amended Explain the contents and significance of the Bill of Rights Discuss the importance of the Thirteenth, Fourteenth, Fifteenth, and Nineteenth Amendments A major problem with the Articles of Confederation had been the nation’s inability to change them without the unanimous consent of all the states. The framers learned this lesson well. One of the strengths they built into the Constitution was the ability to amend it to meet the nation’s needs, reflect the changing times, and address concerns or structural elements they had not anticipated. THE AMENDMENT PROCESS Since ratification in 1789, the Constitution has been amended only twenty-seven times. The first ten amendments were added in 1791. Responding to charges by Anti-Federalists that the Constitution made the national government too powerful and provided no protections for the rights of individuals, the newly elected federal government tackled the issue of guaranteeing liberties for American citizens. James Madison , a member of Congress from Virginia, took the lead in drafting nineteen potential changes to the Constitution. Madison followed the procedure outlined in Article V that says amendments can originate from one of two sources. First, they can be proposed by Congress. Then, they must be approved by a two-thirds majority in both the House and the Senate before being sent to the states for potential ratification. States have two ways to ratify or defeat a proposed amendment. First, if three-quarters of state legislatures vote to approve an amendment, it becomes part of the Constitution. Second, if three-quarters of state-ratifying conventions support the amendment, it is ratified. A second method of proposal of an amendment allows for the petitioning of Congress by the states: Upon receiving such petitions from two-thirds of the states, Congress must call a convention for the purpose of proposing amendments, which would then be forwarded to the states for ratification by the required three-quarters. All the current constitutional amendments were created using the first method of proposal (via Congress). Having drafted nineteen proposed amendments, Madison submitted them to Congress. Only twelve were approved by two-thirds of both the Senate and the House of Representatives and sent to the states for ratification. Of these, only ten were accepted by three-quarters of the state legislatures. In 1791, these first ten amendments were added to the Constitution and became known as the Bill of Rights . The ability to change the Constitution has made it a flexible, living document that can respond to the nation’s changing needs and has helped it remain in effect for more than 225 years. At the same time, the framers made amending the document sufficiently difficult that it has not been changed repeatedly; only seventeen amendments have been added since the ratification of the first ten (one of these, the Twenty-Seventh Amendment, was among Madison’s rejected nine proposals). KEY CONSTITUTIONAL CHANGES The Bill of Rights was intended to quiet the fears of Anti-Federalists that the Constitution did not adequately protect individual liberties and thus encourage their support of the new national government. Many of these first ten amendments were based on provisions of the English Bill of Rights and the Virginia Declaration of Rights . For example, the right to bear arms for protection ( Second Amendment ), the right not to have to provide shelter and provision for soldiers in peacetime ( Third Amendment ), the right to a trial by jury (Sixth and Seventh Amendments), and protection from excessive fines and from cruel and unusual punishment ( Eighth Amendment ) are taken from the English Bill of Rights. The Fifth Amendment , which requires among other things that people cannot be deprived of their life, liberty, or property except by a legal proceeding, was also greatly influenced by English law as well as the protections granted to Virginians in the Virginia Declaration of Rights. Link to Learning Learn more about the formal process of amending the Constitution and view exhibits related to the passage of specific amendments at the National Archives website. Other liberties, however, do not derive from British precedents. The protections for religion, speech, the press, and assembly that are granted by the First Amendment did not exist under English law. (The right to petition the government did, however.) The prohibition in the First Amendment against the establishment of an official church by the federal government differed significantly from both English precedent and the practice of several states that had official churches. The Fourth Amendment , which protects Americans from unwarranted search and seizure of their property, was also new. The Ninth and Tenth Amendments were intended to provide yet another assurance that people’s rights would be protected and that the federal government would not become too powerful. The Ninth Amendment guarantees that liberties extend beyond those described in the preceding documents. This was an important acknowledgment that the protected rights were extensive, and the government should not attempt to interfere with them. The Supreme Court, for example, has held that the Ninth Amendment protects the right to privacy even though none of the preceding amendments explicitly mentions this right. The Tenth Amendment , one of the first submitted to the states for ratification, ensures that states possess all powers not explicitly assigned to the federal government by the Constitution. This guarantee protects states’ reserved powers to regulate such things as marriage, divorce, and intrastate transportation and commerce, and to pass laws affecting education and public health and safety. Of the later amendments only one, the Twenty-First, repealed another amendment, the Eighteenth, which had prohibited the manufacture, import, export, distribution, transportation, and sale of alcoholic beverages. Other amendments rectify problems that have arisen over the years or that reflect changing times. For example, the Seventeenth Amendment , ratified in 1913, gave voters the right to directly elect U.S. senators. The Twentieth Amendment , which was ratified in 1933 during the Great Depression, moved the date of the presidential inauguration from March to January. In a time of crisis, like a severe economic depression, the president needed to take office almost immediately after being elected, and modern transportation allowed the new president to travel to the nation’s capital quicker than before. The Twenty-Second Amendment , added in 1955, limits the president to two terms in office, and the Twenty-Seventh Amendment , first submitted for ratification in 1789, regulates the implementation of laws regarding salary increases or decreases for members of Congress. Of the remaining amendments, four are of especially great significance. The Thirteenth, Fourteenth, and Fifteenth Amendments, ratified at the end of the Civil War, changed the lives of African Americans who had been held in slavery. The Thirteenth Amendment abolished slavery in the United States. The Fourteenth Amendment granted citizenship to African Americans and equal protection under the law regardless of race or color. It also prohibited states from depriving their residents of life, liberty, or property without a legal proceeding. Over the years, the Fourteenth Amendment has been used to require states to protect most of the same federal freedoms granted by the Bill of Rights. The Fifteenth and Nineteenth Amendments extended the right to vote. The Constitution had given states the power to set voting requirements, but the states had used this authority to deny women the right to vote. Most states before the 1830s had also used this authority to deny suffrage to property-less men and often to African American men as well. When states began to change property requirements for voters in the 1830s, many that had allowed free, property-owning African American men to vote restricted the suffrage to white men. The Fifteenth Amendment gave men the right to vote regardless of race or color, but women were still prohibited from voting in most states. After many years of campaigns for suffrage, as shown in Figure 2.15 , the Nineteenth Amendment finally gave women the right to vote in 1920. Subsequent amendments further extended the suffrage. The Twenty-Third Amendment (1961) allowed residents of Washington, DC to vote for the president. The Twenty-Fourth Amendment (1964) abolished the use of poll taxes. Many southern states had used a poll tax, a tax placed on voting, to prevent poor African Americans from voting. Thus, the states could circumvent the Fifteenth Amendment; they argued that they were denying African American men and women the right to vote not because of their race but because of their inability to pay the tax. The last great extension of the suffrage occurred in 1971 in the midst of the Vietnam War. The Twenty-Sixth Amendment reduced the voting age from twenty-one to eighteen. Many people had complained that the young men who were fighting in Vietnam should have the right to vote for or against those making decisions that might literally mean life or death for them. Many other amendments have been proposed over the years, including an amendment to guarantee equal rights to women, but all have failed. Get Connected! Guaranteeing Your First Amendment Rights The liberties of U.S. citizens are protected by the Bill of Rights, but potential or perceived threats to these freedoms arise constantly. This is especially true regarding First Amendment rights. Read about some of these threats at the American Civil Liberties Union (ACLU) website and let people know how you feel about these issues. What issue regarding First Amendment protections causes you the most concern?
anatomy_and_physiology
Chapter Objectives After studying this chapter, you will be able to: Identify the main tissue types and discuss their roles in the human body Identify the four types of tissue membranes and the characteristics of each that make them functional Explain the functions of various epithelial tissues and how their forms enable their functions Explain the functions of various connective tissues and how their forms enable their functions Describe the characteristics of muscle tissue and how these enable function Discuss the characteristics of nervous tissue and how these enable information processing and control of muscular and glandular activities Introduction The body contains at least 200 distinct cell types. These cells contain essentially the same internal structures yet they vary enormously in shape and function. The different types of cells are not randomly distributed throughout the body; rather they occur in organized layers, a level of organization referred to as tissue. The micrograph that opens this chapter shows the high degree of organization among different types of cells in the tissue of the cervix. You can also see how that organization breaks down when cancer takes over the regular mitotic functioning of a cell. The variety in shape reflects the many different roles that cells fulfill in your body. The human body starts as a single cell at fertilization. As this fertilized egg divides, it gives rise to trillions of cells, each built from the same blueprint, but organizing into tissues and becoming irreversibly committed to a developmental pathway.
[ { "answer": { "ans_choice": 2, "ans_text": "embryonic" }, "bloom": null, "hl_context": "The next level of organization is the organ , where several types of tissues come together to form a working unit . Just as knowing the structure and function of cells helps you in your study of tissues , knowledge of tissues will help you understand how organs function . <hl> The epithelial and connective tissues are discussed in detail in this chapter . <hl> <hl> Muscle and nervous tissues will be discussed only briefly in this chapter . <hl> <hl> Although there are many types of cells in the human body , they are organized into four broad categories of tissues : epithelial , connective , muscle , and nervous . <hl> Each of these categories is characterized by specific functions that contribute to the overall health and maintenance of the body . A disruption of the structure is a sign of injury or disease . Such changes can be detected through histology , the microscopic study of tissue appearance , organization , and function .", "hl_sentences": "The epithelial and connective tissues are discussed in detail in this chapter . Muscle and nervous tissues will be discussed only briefly in this chapter . Although there are many types of cells in the human body , they are organized into four broad categories of tissues : epithelial , connective , muscle , and nervous .", "question": { "cloze_format": "The ___ is not a type of tissue.", "normal_format": "Which of the following is not a type of tissue?", "question_choices": [ "muscle", "nervous", "embryonic", "epithelial" ], "question_id": "fs-id1433317", "question_text": "Which of the following is not a type of tissue?" }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 0, "ans_text": "differentiation" }, "bloom": "1", "hl_context": "The mesenchymal cell is a multipotent adult stem cell . <hl> These cells can differentiate into any type of connective tissue cells needed for repair and healing of damaged tissue . <hl> Embryonic Origin of Tissues The zygote , or fertilized egg , is a single cell formed by the fusion of an egg and sperm . After fertilization the zygote gives rise to rapid mitotic cycles , generating many cells to form the embryo . <hl> The first embryonic cells generated have the ability to differentiate into any type of cell in the body and , as such , are called totipotent , meaning each has the capacity to divide , differentiate , and develop into a new organism . <hl> As cell proliferation progresses , three major cell lineages are established within the embryo . As explained in a later chapter , each of these lineages of embryonic cells forms the distinct germ layers from which all the tissues and organs of the human body eventually form . Each germ layer is identified by its relative position : ectoderm ( ecto - = “ outer ” ) , mesoderm ( meso - = “ middle ” ) , and endoderm ( endo - = “ inner ” ) . Figure 4.3 shows the types of tissues and organs associated with the each of the three germ layers . Note that epithelial tissue originates in all three layers , whereas nervous tissue derives primarily from the ectoderm and muscle tissue from mesoderm . Interactive Link", "hl_sentences": "These cells can differentiate into any type of connective tissue cells needed for repair and healing of damaged tissue . The first embryonic cells generated have the ability to differentiate into any type of cell in the body and , as such , are called totipotent , meaning each has the capacity to divide , differentiate , and develop into a new organism .", "question": { "cloze_format": "The process by which a less specialized cell matures into a more specialized cell is called ________.", "normal_format": "Which is the process called by which a less specialized cell matures into a more specialized cell?", "question_choices": [ "differentiation", "maturation", "modification", "specialization" ], "question_id": "fs-id1524093", "question_text": "The process by which a less specialized cell matures into a more specialized cell is called ________." }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 1, "ans_text": "ectoderm, mesoderm, and endoderm" }, "bloom": "1", "hl_context": "Epithelial cells derive from all three major embryonic layers . <hl> The epithelia lining the skin , parts of the mouth and nose , and the anus develop from the ectoderm . <hl> <hl> Cells lining the airways and most of the digestive system originate in the endoderm . <hl> <hl> The epithelium that lines vessels in the lymphatic and cardiovascular system derives from the mesoderm and is called an endothelium . <hl> Embryonic Origin of Tissues The zygote , or fertilized egg , is a single cell formed by the fusion of an egg and sperm . After fertilization the zygote gives rise to rapid mitotic cycles , generating many cells to form the embryo . The first embryonic cells generated have the ability to differentiate into any type of cell in the body and , as such , are called totipotent , meaning each has the capacity to divide , differentiate , and develop into a new organism . As cell proliferation progresses , three major cell lineages are established within the embryo . As explained in a later chapter , each of these lineages of embryonic cells forms the distinct germ layers from which all the tissues and organs of the human body eventually form . <hl> Each germ layer is identified by its relative position : ectoderm ( ecto - = “ outer ” ) , mesoderm ( meso - = “ middle ” ) , and endoderm ( endo - = “ inner ” ) . <hl> Figure 4.3 shows the types of tissues and organs associated with the each of the three germ layers . Note that epithelial tissue originates in all three layers , whereas nervous tissue derives primarily from the ectoderm and muscle tissue from mesoderm . Interactive Link", "hl_sentences": "The epithelia lining the skin , parts of the mouth and nose , and the anus develop from the ectoderm . Cells lining the airways and most of the digestive system originate in the endoderm . The epithelium that lines vessels in the lymphatic and cardiovascular system derives from the mesoderm and is called an endothelium . Each germ layer is identified by its relative position : ectoderm ( ecto - = “ outer ” ) , mesoderm ( meso - = “ middle ” ) , and endoderm ( endo - = “ inner ” ) .", "question": { "cloze_format": "Differentiated cells in a developing embryo derive from ________.", "normal_format": "What do differentiated cells in a developing embryo derive from?", "question_choices": [ "endothelium, mesothelium, and epithelium", "ectoderm, mesoderm, and endoderm", "connective tissue, epithelial tissue, and muscle tissue", "epidermis, mesoderm, and endothelium" ], "question_id": "fs-id1097582", "question_text": "Differentiated cells in a developing embryo derive from ________." }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 3, "ans_text": "mucosa" }, "bloom": "1", "hl_context": "The epithelial membrane is composed of epithelium attached to a layer of connective tissue , for example , your skin . The mucous membrane is also a composite of connective and epithelial tissues . <hl> Sometimes called mucosae , these epithelial membranes line the body cavities and hollow passageways that open to the external environment , and include the digestive , respiratory , excretory , and reproductive tracts . <hl> Mucus , produced by the epithelial exocrine glands , covers the epithelial layer . The underlying connective tissue , called the lamina propria ( literally “ own layer ” ) , help support the fragile epithelial layer . A serous membrane is an epithelial membrane composed of mesodermally derived epithelium called the mesothelium that is supported by connective tissue . These membranes line the coelomic cavities of the body , that is , those cavities that do not open to the outside , and they cover the organs located within those cavities . They are essentially membranous bags , with mesothelium lining the inside and connective tissue on the outside . Serous fluid secreted by the cells of the thin squamous mesothelium lubricates the membrane and reduces abrasion and friction between organs . Serous membranes are identified according locations . Three serous membranes line the thoracic cavity ; the two pleura that cover the lungs and the pericardium that covers the heart . A fourth , the peritoneum , is the serous membrane in the abdominal cavity that covers abdominal organs and forms double sheets of mesenteries that suspend many of the digestive organs .", "hl_sentences": "Sometimes called mucosae , these epithelial membranes line the body cavities and hollow passageways that open to the external environment , and include the digestive , respiratory , excretory , and reproductive tracts .", "question": { "cloze_format": "___ lines the body cavities exposed to the external environment.", "normal_format": "Which of the following lines the body cavities exposed to the external environment?", "question_choices": [ "mesothelium", "lamina propria", "mesenteries", "mucosa" ], "question_id": "fs-id1058496", "question_text": "Which of the following lines the body cavities exposed to the external environment?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 2, "ans_text": "simple squamous" }, "bloom": "1", "hl_context": "Simple Epithelium The shape of the cells in the single cell layer of simple epithelium reflects the functioning of those cells . <hl> The cells in simple squamous epithelium have the appearance of thin scales . <hl> <hl> Squamous cell nuclei tend to be flat , horizontal , and elliptical , mirroring the form of the cell . <hl> <hl> The endothelium is the epithelial tissue that lines vessels of the lymphatic and cardiovascular system , and it is made up of a single layer of squamous cells . <hl> Simple squamous epithelium , because of the thinness of the cell , is present where rapid passage of chemical compounds is observed . The alveoli of lungs where gases diffuse , segments of kidney tubules , and the lining of capillaries are also made of simple squamous epithelial tissue . The mesothelium is a simple squamous epithelium that forms the surface layer of the serous membrane that lines body cavities and internal organs . Its primary function is to provide a smooth and protective surface . Mesothelial cells are squamous epithelial cells that secrete a fluid that lubricates the mesothelium .", "hl_sentences": "The cells in simple squamous epithelium have the appearance of thin scales . Squamous cell nuclei tend to be flat , horizontal , and elliptical , mirroring the form of the cell . The endothelium is the epithelial tissue that lines vessels of the lymphatic and cardiovascular system , and it is made up of a single layer of squamous cells .", "question": { "cloze_format": "The ganglion that is responsible for cutaneous sensations of the face is the ___ .", "normal_format": "Which ganglion is responsible for cutaneous sensations of the face?", "question_choices": [ "columnar", "pseudostratified", "simple squamous", "transitional" ], "question_id": "fs-id1493258", "question_text": "Which of the following is the epithelial tissue that lines the interior of blood vessels?" }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 1, "ans_text": "stratified columnar" }, "bloom": null, "hl_context": "View the University of Michigan WebScope to explore the tissue sample in greater detail . <hl> Stratified Epithelium A stratified epithelium consists of several stacked layers of cells . <hl> This epithelium protects against physical and chemical wear and tear . <hl> The stratified epithelium is named by the shape of the most apical layer of cells , closest to the free space . <hl> Stratified squamous epithelium is the most common type of stratified epithelium in the human body . The apical cells are squamous , whereas the basal layer contains either columnar or cuboidal cells . The top layer may be covered with dead cells filled with keratin . Mammalian skin is an example of this dry , keratinized , stratified squamous epithelium . The lining of the mouth cavity is an example of an unkeratinized , stratified squamous epithelium . Stratified cuboidal epithelium and stratified columnar epithelium can also be found in certain glands and ducts , but are uncommon in the human body . <hl> The skin is an epithelial membrane also called the cutaneous membrane . <hl> <hl> It is a stratified squamous epithelial membrane resting on top of connective tissue . <hl> <hl> The apical surface of this membrane is exposed to the external environment and is covered with dead , keratinized cells that help protect the body from desiccation and pathogens . <hl> 4.2 Epithelial Tissue Learning Objectives By the end of this section , you will be able to :", "hl_sentences": "Stratified Epithelium A stratified epithelium consists of several stacked layers of cells . The stratified epithelium is named by the shape of the most apical layer of cells , closest to the free space . The skin is an epithelial membrane also called the cutaneous membrane . It is a stratified squamous epithelial membrane resting on top of connective tissue . The apical surface of this membrane is exposed to the external environment and is covered with dead , keratinized cells that help protect the body from desiccation and pathogens .", "question": { "cloze_format": "The type of epithelial tissue that specializes in moving particles across its surface is ___.", "normal_format": "Which type of epithelial tissue specializes in moving particles across its surface?", "question_choices": [ "transitional", "stratified columnar", "pseudostratified ciliated columnar", "stratified squamous" ], "question_id": "fs-id730244", "question_text": "Which type of epithelial tissue specializes in moving particles across its surface?" }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 0, "ans_text": "holocrine; apocrine" }, "bloom": "1", "hl_context": "<hl> Apocrine secretion accumulates near the apical portion of the cell . <hl> That portion of the cell and its secretory contents pinch off from the cell and are released . Apocrine sweat glands in the axillary and genital areas release fatty secretions that local bacteria break down ; this causes body odor . Both merocrine and apocrine glands continue to produce and secrete their contents with little damage caused to the cell because the nucleus and golgi regions remain intact after secretion . <hl> In contrast , the process of holocrine secretion involves the rupture and destruction of the entire gland cell . <hl> The cell accumulates its secretory products and releases them only when it bursts . New gland cells differentiate from cells in the surrounding tissue to replace those lost by secretion . The sebaceous glands that produce the oils on the skin and hair are holocrine glands / cells ( Figure 4.11 ) .", "hl_sentences": "Apocrine secretion accumulates near the apical portion of the cell . In contrast , the process of holocrine secretion involves the rupture and destruction of the entire gland cell .", "question": { "cloze_format": "The ________ exocrine gland stores its secretion until the glandular cell ruptures, whereas the ________ gland releases its apical region and reforms.", "normal_format": "Which exocrine gland stores its secretion until the glandular cell ruptures, whereas which gland releases its apical region and reforms?", "question_choices": [ "holocrine; apocrine", "eccrine; endocrine", "apocrine; holocrine", "eccrine; apocrine" ], "question_id": "fs-id1103469", "question_text": "The ________ exocrine gland stores its secretion until the glandular cell ruptures, whereas the ________ gland releases its apical region and reforms." }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 1, "ans_text": "cells, ground substance, and protein fibers" }, "bloom": null, "hl_context": "As may be obvious from its name , one of the major functions of connective tissue is to connect tissues and organs . Unlike epithelial tissue , which is composed of cells closely packed with little or no extracellular space in between , connective tissue cells are dispersed in a matrix . The matrix usually includes a large amount of extracellular material produced by the connective tissue cells that are embedded within it . The matrix plays a major role in the functioning of this tissue . The major component of the matrix is a ground substance often crisscrossed by protein fibers . This ground substance is usually a fluid , but it can also be mineralized and solid , as in bones . <hl> Connective tissues come in a vast variety of forms , yet they typically have in common three characteristic components : cells , large amounts of amorphous ground substance , and protein fibers . <hl> The amount and structure of each component correlates with the function of the tissue , from the rigid ground substance in bones supporting the body to the inclusion of specialized cells ; for example , a phagocytic cell that engulfs pathogens and also rids tissue of cellular debris .", "hl_sentences": "Connective tissues come in a vast variety of forms , yet they typically have in common three characteristic components : cells , large amounts of amorphous ground substance , and protein fibers .", "question": { "cloze_format": "The three essential components that connective tissue is made of are ___.", "normal_format": "Connective tissue is made of which three essential components?", "question_choices": [ "cells, ground substance, and carbohydrate fibers", "cells, ground substance, and protein fibers", "collagen, ground substance, and protein fibers", "matrix, ground substance, and fluid" ], "question_id": "fs-id1153084", "question_text": "Connective tissue is made of which three essential components?" }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 1, "ans_text": "adipose tissue" }, "bloom": "1", "hl_context": "<hl> Adipose tissue consists mostly of fat storage cells , with little extracellular matrix ( Figure 4.13 ) . <hl> A large number of capillaries allow rapid storage and mobilization of lipid molecules . White adipose tissue is most abundant . It can appear yellow and owes its color to carotene and related pigments from plant food . White fat contributes mostly to lipid storage and can serve as insulation from cold temperatures and mechanical injuries . White adipose tissue can be found protecting the kidneys and cushioning the back of the eye . Brown adipose tissue is more common in infants , hence the term “ baby fat . ” In adults , there is a reduced amount of brown fat and it is found mainly in the neck and clavicular regions of the body . The many mitochondria in the cytoplasm of brown adipose tissue help explain its efficiency at metabolizing stored fat . Brown adipose tissue is thermogenic , meaning that as it breaks down fats , it releases metabolic heat , rather than producing adenosine triphosphate ( ATP ) , a key molecule used in metabolism . Areolar tissue shows little specialization . It contains all the cell types and fibers previously described and is distributed in a random , web-like fashion . It fills the spaces between muscle fibers , surrounds blood and lymph vessels , and supports organs in the abdominal cavity . Areolar tissue underlies most epithelia and represents the connective tissue component of epithelial membranes , which are described further in a later section . Connective tissues perform many functions in the body , but most importantly , they support and connect other tissues ; from the connective tissue sheath that surrounds muscle cells , to the tendons that attach muscles to bones , and to the skeleton that supports the positions of the body . Protection is another major function of connective tissue , in the form of fibrous capsules and bones that protect delicate organs and , of course , the skeletal system . Specialized cells in connective tissue defend the body from microorganisms that enter the body . Transport of fluid , nutrients , waste , and chemical messengers is ensured by specialized fluid connective tissues , such as blood and lymph . <hl> Adipose cells store surplus energy in the form of fat and contribute to the thermal insulation of the body . <hl>", "hl_sentences": "Adipose tissue consists mostly of fat storage cells , with little extracellular matrix ( Figure 4.13 ) . Adipose cells store surplus energy in the form of fat and contribute to the thermal insulation of the body .", "question": { "cloze_format": "The ___ is a connective tissue that specializes in storage of fat.", "normal_format": "Which connective tissue specializes in storage of fat?", "question_choices": [ "tendon", "adipose tissue", "reticular tissue", "dense connective tissue" ], "question_id": "fs-id1303296", "question_text": "Which connective tissue specializes in storage of fat?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 2, "ans_text": "dense regular connective tissue" }, "bloom": "3", "hl_context": "<hl> Dense connective tissue contains more collagen fibers than does loose connective tissue . <hl> <hl> As a consequence , it displays greater resistance to stretching . <hl> There are two major categories of dense connective tissue : regular and irregular . Dense regular connective tissue fibers are parallel to each other , enhancing tensile strength and resistance to stretching in the direction of the fiber orientations . Ligaments and tendons are made of dense regular connective tissue , but in ligaments not all fibers are parallel . Dense regular elastic tissue contains elastin fibers in addition to collagen fibers , which allows the ligament to return to its original length after stretching . The ligaments in the vocal folds and between the vertebrae in the vertebral column are elastic . The three broad categories of connective tissue are classified according to the characteristics of their ground substance and the types of fibers found within the matrix ( Table 4.1 ) . Connective tissue proper includes loose connective tissue and dense connective tissue . Both tissues have a variety of cell types and protein fibers suspended in a viscous ground substance . <hl> Dense connective tissue is reinforced by bundles of fibers that provide tensile strength , elasticity , and protection . <hl> In loose connective tissue , the fibers are loosely organized , leaving large spaces in between . Supportive connective tissue — bone and cartilage — provide structure and strength to the body and protect soft tissues . A few distinct cell types and densely packed fibers in a matrix characterize these tissues . In bone , the matrix is rigid and described as calcified because of the deposited calcium salts . In fluid connective tissue , in other words , lymph and blood , various specialized cells circulate in a watery fluid containing salts , nutrients , and dissolved proteins .", "hl_sentences": "Dense connective tissue contains more collagen fibers than does loose connective tissue . As a consequence , it displays greater resistance to stretching . Dense connective tissue is reinforced by bundles of fibers that provide tensile strength , elasticity , and protection .", "question": { "cloze_format": "Ligaments connect bones together and withstand a lot of stress. The type of connective tissue you should expect ligaments to contain is the ___.", "normal_format": "Ligaments connect bones together and withstand a lot of stress. What type of connective tissue should you expect ligaments to contain?", "question_choices": [ "areolar tissue", "adipose tissue", "dense regular connective tissue", "dense irregular connective tissue" ], "question_id": "fs-id1139303", "question_text": "Ligaments connect bones together and withstand a lot of stress. What type of connective tissue should you expect ligaments to contain?" }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 1, "ans_text": "mesenchyme" }, "bloom": "1", "hl_context": "<hl> The mesenchymal cell is a multipotent adult stem cell . <hl> These cells can differentiate into any type of connective tissue cells needed for repair and healing of damaged tissue . All connective tissues derive from the mesodermal layer of the embryo ( see Figure 4.3 ) . <hl> The first connective tissue to develop in the embryo is mesenchyme , the stem cell line from which all connective tissues are later derived . <hl> Clusters of mesenchymal cells are scattered throughout adult tissue and supply the cells needed for replacement and repair after a connective tissue injury . A second type of embryonic connective tissue forms in the umbilical cord , called mucous connective tissue or Wharton ’ s jelly . This tissue is no longer present after birth , leaving only scattered mesenchymal cells throughout the body .", "hl_sentences": "The mesenchymal cell is a multipotent adult stem cell . The first connective tissue to develop in the embryo is mesenchyme , the stem cell line from which all connective tissues are later derived .", "question": { "cloze_format": "In adults, new connective tissue cells originate from the ________.", "normal_format": "In adults, new connective tissue cells originate from what?\n", "question_choices": [ "mesoderm", "mesenchyme", "ectoderm", "endoderm" ], "question_id": "fs-id1076026", "question_text": "In adults, new connective tissue cells originate from the ________." }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 3, "ans_text": "osteocytes" }, "bloom": "1", "hl_context": "Bone is the hardest connective tissue . It provides protection to internal organs and supports the body . Bone ’ s rigid extracellular matrix contains mostly collagen fibers embedded in a mineralized ground substance containing hydroxyapatite , a form of calcium phosphate . Both components of the matrix , organic and inorganic , contribute to the unusual properties of bone . Without collagen , bones would be brittle and shatter easily . Without mineral crystals , bones would flex and provide little support . <hl> Osteocytes , bone cells like chondrocytes , are located within lacunae . <hl> The histology of transverse tissue from long bone shows a typical arrangement of osteocytes in concentric circles around a central canal . Bone is a highly vascularized tissue . Unlike cartilage , bone tissue can recover from injuries in a relatively short time .", "hl_sentences": "Osteocytes , bone cells like chondrocytes , are located within lacunae .", "question": { "cloze_format": "In bone, the main cells are ________.", "normal_format": "What are the main cells in bone?", "question_choices": [ "fibroblasts", "chondrocytes", "lymphocytes", "osteocytes" ], "question_id": "fs-id1211308", "question_text": "In bone, the main cells are ________." }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 0, "ans_text": "skeletal muscle only" }, "bloom": "1", "hl_context": "Skeletal muscle is attached to bones and its contraction makes possible locomotion , facial expressions , posture , and other voluntary movements of the body . Forty percent of your body mass is made up of skeletal muscle . Skeletal muscles generate heat as a byproduct of their contraction and thus participate in thermal homeostasis . Shivering is an involuntary contraction of skeletal muscles in response to perceived lower than normal body temperature . The muscle cell , or myocyte , develops from myoblasts derived from the mesoderm . Myocytes and their numbers remain relatively constant throughout life . <hl> Skeletal muscle tissue is arranged in bundles surrounded by connective tissue . <hl> <hl> Under the light microscope , muscle cells appear striated with many nuclei squeezed along the membranes . <hl> The striation is due to the regular alternation of the contractile proteins actin and myosin , along with the structural proteins that couple the contractile proteins to connective tissues . <hl> The cells are multinucleated as a result of the fusion of the many myoblasts that fuse to form each long muscle fiber . <hl>", "hl_sentences": "Skeletal muscle tissue is arranged in bundles surrounded by connective tissue . Under the light microscope , muscle cells appear striated with many nuclei squeezed along the membranes . The cells are multinucleated as a result of the fusion of the many myoblasts that fuse to form each long muscle fiber .", "question": { "cloze_format": "Striations, cylindrical cells, and multiple nuclei are observed in ________.", "normal_format": "Where are striations, cylindrical cells, and multiple nuclei observed?", "question_choices": [ "skeletal muscle only", "cardiac muscle only", "smooth muscle only", "skeletal and cardiac muscles" ], "question_id": "fs-id1491111", "question_text": "Striations, cylindrical cells, and multiple nuclei are observed in ________." }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 0, "ans_text": "myoblasts" }, "bloom": "1", "hl_context": "Skeletal muscle is attached to bones and its contraction makes possible locomotion , facial expressions , posture , and other voluntary movements of the body . Forty percent of your body mass is made up of skeletal muscle . Skeletal muscles generate heat as a byproduct of their contraction and thus participate in thermal homeostasis . Shivering is an involuntary contraction of skeletal muscles in response to perceived lower than normal body temperature . <hl> The muscle cell , or myocyte , develops from myoblasts derived from the mesoderm . <hl> Myocytes and their numbers remain relatively constant throughout life . Skeletal muscle tissue is arranged in bundles surrounded by connective tissue . Under the light microscope , muscle cells appear striated with many nuclei squeezed along the membranes . The striation is due to the regular alternation of the contractile proteins actin and myosin , along with the structural proteins that couple the contractile proteins to connective tissues . The cells are multinucleated as a result of the fusion of the many myoblasts that fuse to form each long muscle fiber .", "hl_sentences": "The muscle cell , or myocyte , develops from myoblasts derived from the mesoderm .", "question": { "cloze_format": "The cells of muscles, myocytes, develop from ________.", "normal_format": "Where do the cells of muscles, myocytes, develop from?", "question_choices": [ "myoblasts", "endoderm", "fibrocytes", "chondrocytes" ], "question_id": "fs-id1511818", "question_text": "The cells of muscles, myocytes, develop from ________." }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 0, "ans_text": "neurons" }, "bloom": "1", "hl_context": "<hl> Neurons display distinctive morphology , well suited to their role as conducting cells , with three main parts . <hl> The cell body includes most of the cytoplasm , the organelles , and the nucleus . Dendrites branch off the cell body and appear as thin extensions . A long “ tail , ” the axon , extends from the neuron body and can be wrapped in an insulating layer known as myelin , which is formed by accessory cells . <hl> The synapse is the gap between nerve cells , or between a nerve cell and its target , for example , a muscle or a gland , across which the impulse is transmitted by chemical compounds known as neurotransmitters . <hl> Neurons categorized as multipolar neurons have several dendrites and a single prominent axon . Bipolar neurons possess a single dendrite and axon with the cell body , while unipolar neurons have only a single process extending out from the cell body , which divides into a functional dendrite and into a functional axon . When a neuron is sufficiently stimulated , it generates an action potential that propagates down the axon towards the synapse . If enough neurotransmitters are released at the synapse to stimulate the next neuron or target , a response is generated . Nervous tissue is characterized as being excitable and capable of sending and receiving electrochemical signals that provide the body with information . Two main classes of cells make up nervous tissue : the neuron and neuroglia ( Figure 4.19 ) . <hl> Neurons propagate information via electrochemical impulses , called action potentials , which are biochemically linked to the release of chemical signals . <hl> Neuroglia play an essential role in supporting neurons and modulating their information propagation .", "hl_sentences": "Neurons display distinctive morphology , well suited to their role as conducting cells , with three main parts . The synapse is the gap between nerve cells , or between a nerve cell and its target , for example , a muscle or a gland , across which the impulse is transmitted by chemical compounds known as neurotransmitters . Neurons propagate information via electrochemical impulses , called action potentials , which are biochemically linked to the release of chemical signals .", "question": { "cloze_format": "The cells responsible for the transmission of the nerve impulse are ________.", "normal_format": "What are the cells responsible for the transmission of the nerve impulse?", "question_choices": [ "neurons", "oligodendrocytes", "astrocytes", "microglia" ], "question_id": "fs-id12720570", "question_text": "The cells responsible for the transmission of the nerve impulse are ________." }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 1, "ans_text": "axon" }, "bloom": "1", "hl_context": "Neurons display distinctive morphology , well suited to their role as conducting cells , with three main parts . The cell body includes most of the cytoplasm , the organelles , and the nucleus . Dendrites branch off the cell body and appear as thin extensions . <hl> A long “ tail , ” the axon , extends from the neuron body and can be wrapped in an insulating layer known as myelin , which is formed by accessory cells . <hl> The synapse is the gap between nerve cells , or between a nerve cell and its target , for example , a muscle or a gland , across which the impulse is transmitted by chemical compounds known as neurotransmitters . Neurons categorized as multipolar neurons have several dendrites and a single prominent axon . Bipolar neurons possess a single dendrite and axon with the cell body , while unipolar neurons have only a single process extending out from the cell body , which divides into a functional dendrite and into a functional axon . When a neuron is sufficiently stimulated , it generates an action potential that propagates down the axon towards the synapse . If enough neurotransmitters are released at the synapse to stimulate the next neuron or target , a response is generated .", "hl_sentences": "A long “ tail , ” the axon , extends from the neuron body and can be wrapped in an insulating layer known as myelin , which is formed by accessory cells .", "question": { "cloze_format": "The nerve impulse travels down a(n) ________, away from the cell body.", "normal_format": "Down what does the nerve impulse travel, away from the body?", "question_choices": [ "dendrite", "axon", "microglia", "collagen fiber" ], "question_id": "fs-id865633", "question_text": "The nerve impulse travels down a(n) ________, away from the cell body." }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 3, "ans_text": "astrocytes" }, "bloom": null, "hl_context": "The second class of neural cells comprises the neuroglia or glial cells , which have been characterized as having a simple support role . The word “ glia ” comes from the Greek word for glue . Recent research is shedding light on the more complex role of neuroglia in the function of the brain and nervous system . Astrocyte cells , named for their distinctive star shape , are abundant in the central nervous system . <hl> The astrocytes have many functions , including regulation of ion concentration in the intercellular space , uptake and / or breakdown of some neurotransmitters , and formation of the blood-brain barrier , the membrane that separates the circulatory system from the brain . <hl> Microglia protect the nervous system against infection but are not nervous tissue because they are related to macrophages . Oligodendrocyte cells produce myelin in the central nervous system ( brain and spinal cord ) while the Schwann cell produces myelin in the peripheral nervous system ( Figure 4.20 ) . 4.6 Tissue Injury and Aging Learning Objectives By the end of this section , you will be able to :", "hl_sentences": "The astrocytes have many functions , including regulation of ion concentration in the intercellular space , uptake and / or breakdown of some neurotransmitters , and formation of the blood-brain barrier , the membrane that separates the circulatory system from the brain .", "question": { "cloze_format": "The central nervous system cells that regulate ions, regulate the uptake and/or breakdown of some neurotransmitters, and contribute to the formation of the blood-brain barrier are ___.", "normal_format": "Which of the following central nervous system cells regulate ions, regulate the uptake and/or breakdown of some neurotransmitters, and contribute to the formation of the blood-brain barrier?", "question_choices": [ "microglia", "neuroglia", "oligodendrocytes", "astrocytes" ], "question_id": "fs-id1436751", "question_text": "Which of the following central nervous system cells regulate ions, regulate the uptake and/or breakdown of some neurotransmitters, and contribute to the formation of the blood-brain barrier?" }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 2, "ans_text": "fever" }, "bloom": null, "hl_context": "<hl> The four cardinal signs of inflammation — redness , swelling , pain , and local heat — were first recorded in antiquity . <hl> Cornelius Celsus is credited with documenting these signs during the days of the Roman Empire , as early as the first century AD . <hl> A fifth sign , loss of function , may also accompany inflammation . <hl>", "hl_sentences": "The four cardinal signs of inflammation — redness , swelling , pain , and local heat — were first recorded in antiquity . A fifth sign , loss of function , may also accompany inflammation .", "question": { "cloze_format": "The processe that is not a cardinal sign of inflammation is ___.", "normal_format": "Which of the following processes is not a cardinal sign of inflammation?", "question_choices": [ "redness", "heat", "fever", "swelling" ], "question_id": "fs-id912375", "question_text": "Which of the following processes is not a cardinal sign of inflammation?" }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 1, "ans_text": "histamine" }, "bloom": "3", "hl_context": "<hl> Upon tissue injury , damaged cells release inflammatory chemical signals that evoke local vasodilation , the widening of the blood vessels . <hl> <hl> Increased blood flow results in apparent redness and heat . <hl> <hl> In response to injury , mast cells present in tissue degranulate , releasing the potent vasodilator histamine . <hl> Increased blood flow and inflammatory mediators recruit white blood cells to the site of inflammation . The endothelium lining the local blood vessel becomes “ leaky ” under the influence of histamine and other inflammatory mediators allowing neutrophils , macrophages , and fluid to move from the blood into the interstitial tissue spaces . The excess liquid in tissue causes swelling , more properly called edema . The swollen tissues squeezing pain receptors cause the sensation of pain . Prostaglandins released from injured cells also activate pain neurons . Non-steroidal anti-inflammatory drugs ( NSAIDs ) reduce pain because they inhibit the synthesis of prostaglandins . High levels of NSAIDs reduce inflammation . Antihistamines decrease allergies by blocking histamine receptors and as a result the histamine response . The mast cell , found in connective tissue proper , has many cytoplasmic granules . These granules contain the chemical signals histamine and heparin . <hl> When irritated or damaged , mast cells release histamine , an inflammatory mediator , which causes vasodilation and increased blood flow at a site of injury or infection , along with itching , swelling , and redness you recognize as an allergic response . <hl> Like blood cells , mast cells are derived from hematopoietic stem cells and are part of the immune system .", "hl_sentences": "Upon tissue injury , damaged cells release inflammatory chemical signals that evoke local vasodilation , the widening of the blood vessels . Increased blood flow results in apparent redness and heat . In response to injury , mast cells present in tissue degranulate , releasing the potent vasodilator histamine . When irritated or damaged , mast cells release histamine , an inflammatory mediator , which causes vasodilation and increased blood flow at a site of injury or infection , along with itching , swelling , and redness you recognize as an allergic response .", "question": { "cloze_format": "When a mast cell reacts to an irritation, it releases the ___ chemical.", "normal_format": "When a mast cell reacts to an irritation, which of the following chemicals does it release?", "question_choices": [ "collagen", "histamine", "hyaluronic acid", "meylin" ], "question_id": "fs-id1467980", "question_text": "When a mast cell reacts to an irritation, which of the following chemicals does it release?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 1, "ans_text": "loss of mass" }, "bloom": "1", "hl_context": "According to poet Ralph Waldo Emerson , “ The surest poison is time . ” In fact , biology confirms that many functions of the body decline with age . All the cells , tissues , and organs are affected by senescence , with noticeable variability between individuals owing to different genetic makeup and lifestyles . The outward signs of aging are easily recognizable . The skin and other tissues become thinner and drier , reducing their elasticity , contributing to wrinkles and high blood pressure . Hair turns gray because follicles produce less melanin , the brown pigment of hair and the iris of the eye . The face looks flabby because elastic and collagen fibers decrease in connective tissue and muscle tone is lost . Glasses and hearing aids may become parts of life as the senses slowly deteriorate , all due to reduced elasticity . Overall height decreases as the bones lose calcium and other minerals . With age , fluid decreases in the fibrous cartilage disks intercalated between the vertebrae in the spine . Joints lose cartilage and stiffen . <hl> Many tissues , including those in muscles , lose mass through a process called atrophy . <hl> Lumps and rigidity become more widespread . As a consequence , the passageways , blood vessels , and airways become more rigid . The brain and spinal cord lose mass . Nerves do not transmit impulses with the same speed and frequency as in the past . Some loss of thought clarity and memory can accompany aging . More severe problems are not necessarily associated with the aging process and may be symptoms of underlying illness .", "hl_sentences": "Many tissues , including those in muscles , lose mass through a process called atrophy .", "question": { "cloze_format": "Atrophy refers to ________.", "normal_format": "What is atrophy refers to?", "question_choices": [ "loss of elasticity", "loss of mass", "loss of rigidity", "loss of permeability" ], "question_id": "fs-id1148822", "question_text": "Atrophy refers to ________." }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 2, "ans_text": "genetic factors" }, "bloom": null, "hl_context": "<hl> The progressive impact of aging on the body varies considerably among individuals , but Studies indicate , however , that exercise and healthy lifestyle choices can slow down the deterioration of the body that comes with old age . <hl>", "hl_sentences": "The progressive impact of aging on the body varies considerably among individuals , but Studies indicate , however , that exercise and healthy lifestyle choices can slow down the deterioration of the body that comes with old age .", "question": { "cloze_format": "Individuals can slow the rate of aging by modifying all of these lifestyle aspects except for ________.", "normal_format": "Individuals can slow the rate of aging by modifying all of these lifestyle aspects except for which of the following?", "question_choices": [ "diet", "exercise", "genetic factors", "stress" ], "question_id": "fs-id1518097", "question_text": "Individuals can slow the rate of aging by modifying all of these lifestyle aspects except for ________." }, "references_are_paraphrase": 0 } ]
4
4.1 Types of Tissues Learning Objectives By the end of this section, you will be able to: Identify the four main tissue types Discuss the functions of each tissue type Relate the structure of each tissue type to their function Discuss the embryonic origin of tissue Identify the three major germ layers Identify the main types of tissue membranes The term tissue is used to describe a group of cells found together in the body. The cells within a tissue share a common embryonic origin. Microscopic observation reveals that the cells in a tissue share morphological features and are arranged in an orderly pattern that achieves the tissue’s functions. From the evolutionary perspective, tissues appear in more complex organisms. For example, multicellular protists, ancient eukaryotes, do not have cells organized into tissues. Although there are many types of cells in the human body, they are organized into four broad categories of tissues: epithelial, connective, muscle, and nervous. Each of these categories is characterized by specific functions that contribute to the overall health and maintenance of the body. A disruption of the structure is a sign of injury or disease. Such changes can be detected through histology , the microscopic study of tissue appearance, organization, and function. The Four Types of Tissues Epithelial tissue , also referred to as epithelium, refers to the sheets of cells that cover exterior surfaces of the body, line internal cavities and passageways, and form certain glands. Connective tissue , as its name implies, binds the cells and organs of the body together and functions in the protection, support, and integration of all parts of the body. Muscle tissue is excitable, responding to stimulation and contracting to provide movement, and occurs as three major types: skeletal (voluntary) muscle, smooth muscle, and cardiac muscle in the heart. Nervous tissue is also excitable, allowing the propagation of electrochemical signals in the form of nerve impulses that communicate between different regions of the body ( Figure 4.2 ). The next level of organization is the organ, where several types of tissues come together to form a working unit. Just as knowing the structure and function of cells helps you in your study of tissues, knowledge of tissues will help you understand how organs function. The epithelial and connective tissues are discussed in detail in this chapter. Muscle and nervous tissues will be discussed only briefly in this chapter. Embryonic Origin of Tissues The zygote, or fertilized egg, is a single cell formed by the fusion of an egg and sperm. After fertilization the zygote gives rise to rapid mitotic cycles, generating many cells to form the embryo. The first embryonic cells generated have the ability to differentiate into any type of cell in the body and, as such, are called totipotent , meaning each has the capacity to divide, differentiate, and develop into a new organism. As cell proliferation progresses, three major cell lineages are established within the embryo. As explained in a later chapter, each of these lineages of embryonic cells forms the distinct germ layers from which all the tissues and organs of the human body eventually form. Each germ layer is identified by its relative position: ectoderm (ecto- = “outer”), mesoderm (meso- = “middle”), and endoderm (endo- = “inner”). Figure 4.3 shows the types of tissues and organs associated with the each of the three germ layers. Note that epithelial tissue originates in all three layers, whereas nervous tissue derives primarily from the ectoderm and muscle tissue from mesoderm. Interactive Link View this slideshow to learn more about stem cells. How do somatic stem cells differ from embryonic stem cells? Tissue Membranes A tissue membrane is a thin layer or sheet of cells that covers the outside of the body (for example, skin), the organs (for example, pericardium), internal passageways that lead to the exterior of the body (for example, abdominal mesenteries), and the lining of the moveable joint cavities. There are two basic types of tissue membranes: connective tissue and epithelial membranes ( Figure 4.4 ). Connective Tissue Membranes The connective tissue membrane is formed solely from connective tissue. These membranes encapsulate organs, such as the kidneys, and line our movable joints. A synovial membrane is a type of connective tissue membrane that lines the cavity of a freely movable joint. For example, synovial membranes surround the joints of the shoulder, elbow, and knee. Fibroblasts in the inner layer of the synovial membrane release hyaluronan into the joint cavity. The hyaluronan effectively traps available water to form the synovial fluid, a natural lubricant that enables the bones of a joint to move freely against one another without much friction. This synovial fluid readily exchanges water and nutrients with blood, as do all body fluids. Epithelial Membranes The epithelial membrane is composed of epithelium attached to a layer of connective tissue, for example, your skin. The mucous membrane is also a composite of connective and epithelial tissues. Sometimes called mucosae, these epithelial membranes line the body cavities and hollow passageways that open to the external environment, and include the digestive, respiratory, excretory, and reproductive tracts. Mucus, produced by the epithelial exocrine glands, covers the epithelial layer. The underlying connective tissue, called the lamina propria (literally “own layer”), help support the fragile epithelial layer. A serous membrane is an epithelial membrane composed of mesodermally derived epithelium called the mesothelium that is supported by connective tissue. These membranes line the coelomic cavities of the body, that is, those cavities that do not open to the outside, and they cover the organs located within those cavities. They are essentially membranous bags, with mesothelium lining the inside and connective tissue on the outside. Serous fluid secreted by the cells of the thin squamous mesothelium lubricates the membrane and reduces abrasion and friction between organs. Serous membranes are identified according locations. Three serous membranes line the thoracic cavity; the two pleura that cover the lungs and the pericardium that covers the heart. A fourth, the peritoneum, is the serous membrane in the abdominal cavity that covers abdominal organs and forms double sheets of mesenteries that suspend many of the digestive organs. The skin is an epithelial membrane also called the cutaneous membrane . It is a stratified squamous epithelial membrane resting on top of connective tissue. The apical surface of this membrane is exposed to the external environment and is covered with dead, keratinized cells that help protect the body from desiccation and pathogens. 4.2 Epithelial Tissue Learning Objectives By the end of this section, you will be able to: Explain the structure and function of epithelial tissue Distinguish between tight junctions, anchoring junctions, and gap junctions Distinguish between simple epithelia and stratified epithelia, as well as between squamous, cuboidal, and columnar epithelia Describe the structure and function of endocrine and exocrine glands and their respective secretions Most epithelial tissues are essentially large sheets of cells covering all the surfaces of the body exposed to the outside world and lining the outside of organs. Epithelium also forms much of the glandular tissue of the body. Skin is not the only area of the body exposed to the outside. Other areas include the airways, the digestive tract, as well as the urinary and reproductive systems, all of which are lined by an epithelium. Hollow organs and body cavities that do not connect to the exterior of the body, which includes, blood vessels and serous membranes, are lined by endothelium (plural = endothelia), which is a type of epithelium. Epithelial cells derive from all three major embryonic layers. The epithelia lining the skin, parts of the mouth and nose, and the anus develop from the ectoderm. Cells lining the airways and most of the digestive system originate in the endoderm. The epithelium that lines vessels in the lymphatic and cardiovascular system derives from the mesoderm and is called an endothelium. All epithelia share some important structural and functional features. This tissue is highly cellular, with little or no extracellular material present between cells. Adjoining cells form a specialized intercellular connection between their cell membranes called a cell junction . The epithelial cells exhibit polarity with differences in structure and function between the exposed or apical facing surface of the cell and the basal surface close to the underlying body structures. The basal lamina , a mixture of glycoproteins and collagen, provides an attachment site for the epithelium, separating it from underlying connective tissue. The basal lamina attaches to a reticular lamina , which is secreted by the underlying connective tissue, forming a basement membrane that helps hold it all together. Epithelial tissues are nearly completely avascular. For instance, no blood vessels cross the basement membrane to enter the tissue, and nutrients must come by diffusion or absorption from underlying tissues or the surface. Many epithelial tissues are capable of rapidly replacing damaged and dead cells. Sloughing off of damaged or dead cells is a characteristic of surface epithelium and allows our airways and digestive tracts to rapidly replace damaged cells with new cells. Generalized Functions of Epithelial Tissue Epithelial tissues provide the body’s first line of protection from physical, chemical, and biological wear and tear. The cells of an epithelium act as gatekeepers of the body controlling permeability and allowing selective transfer of materials across a physical barrier. All substances that enter the body must cross an epithelium. Some epithelia often include structural features that allow the selective transport of molecules and ions across their cell membranes. Many epithelial cells are capable of secretion and release mucous and specific chemical compounds onto their apical surfaces. The epithelium of the small intestine releases digestive enzymes, for example. Cells lining the respiratory tract secrete mucous that traps incoming microorganisms and particles. A glandular epithelium contains many secretory cells. The Epithelial Cell Epithelial cells are typically characterized by the polarized distribution of organelles and membrane-bound proteins between their basal and apical surfaces. Particular structures found in some epithelial cells are an adaptation to specific functions. Certain organelles are segregated to the basal sides, whereas other organelles and extensions, such as cilia, when present, are on the apical surface. Cilia are microscopic extensions of the apical cell membrane that are supported by microtubules. They beat in unison and move fluids as well as trapped particles. Ciliated epithelium lines the ventricles of the brain where it helps circulate the cerebrospinal fluid. The ciliated epithelium of your airway forms a mucociliary escalator that sweeps particles of dust and pathogens trapped in the secreted mucous toward the throat. It is called an escalator because it continuously pushes mucous with trapped particles upward. In contrast, nasal cilia sweep the mucous blanket down towards your throat. In both cases, the transported materials are usually swallowed, and end up in the acidic environment of your stomach. Cell to Cell Junctions Cells of epithelia are closely connected and are not separated by intracellular material. Three basic types of connections allow varying degrees of interaction between the cells: tight junctions, anchoring junctions, and gap junctions ( Figure 4.5 ). At one end of the spectrum is the tight junction , which separates the cells into apical and basal compartments. When two adjacent epithelial cells form a tight junction, there is no extracellular space between them and the movement of substances through the extracellular space between the cells is blocked. This enables the epithelia to act as selective barriers. An anchoring junction includes several types of cell junctions that help stabilize epithelial tissues. Anchoring junctions are common on the lateral and basal surfaces of cells where they provide strong and flexible connections. There are three types of anchoring junctions: desmosomes, hemidesmosomes, and adherens. Desmosomes occur in patches on the membranes of cells. The patches are structural proteins on the inner surface of the cell’s membrane. The adhesion molecule, cadherin, is embedded in these patches and projects through the cell membrane to link with the cadherin molecules of adjacent cells. These connections are especially important in holding cells together. Hemidesmosomes, which look like half a desmosome, link cells to the extracellular matrix, for example, the basal lamina. While similar in appearance to desmosomes, they include the adhesion proteins called integrins rather than cadherins. Adherens junctions use either cadherins or integrins depending on whether they are linking to other cells or matrix. The junctions are characterized by the presence of the contractile protein actin located on the cytoplasmic surface of the cell membrane. The actin can connect isolated patches or form a belt-like structure inside the cell. These junctions influence the shape and folding of the epithelial tissue. In contrast with the tight and anchoring junctions, a gap junction forms an intercellular passageway between the membranes of adjacent cells to facilitate the movement of small molecules and ions between the cytoplasm of adjacent cells. These junctions allow electrical and metabolic coupling of adjacent cells, which coordinates function in large groups of cells. Classification of Epithelial Tissues Epithelial tissues are classified according to the shape of the cells and number of the cell layers formed ( Figure 4.6 ). Cell shapes can be squamous (flattened and thin), cuboidal (boxy, as wide as it is tall), or columnar (rectangular, taller than it is wide). Similarly, the number of cell layers in the tissue can be one—where every cell rests on the basal lamina—which is a simple epithelium, or more than one, which is a stratified epithelium and only the basal layer of cells rests on the basal lamina. Pseudostratified (pseudo- = “false”) describes tissue with a single layer of irregularly shaped cells that give the appearance of more than one layer. Transitional describes a form of specialized stratified epithelium in which the shape of the cells can vary. Simple Epithelium The shape of the cells in the single cell layer of simple epithelium reflects the functioning of those cells. The cells in simple squamous epithelium have the appearance of thin scales. Squamous cell nuclei tend to be flat, horizontal, and elliptical, mirroring the form of the cell. The endothelium is the epithelial tissue that lines vessels of the lymphatic and cardiovascular system, and it is made up of a single layer of squamous cells. Simple squamous epithelium, because of the thinness of the cell, is present where rapid passage of chemical compounds is observed. The alveoli of lungs where gases diffuse, segments of kidney tubules, and the lining of capillaries are also made of simple squamous epithelial tissue. The mesothelium is a simple squamous epithelium that forms the surface layer of the serous membrane that lines body cavities and internal organs. Its primary function is to provide a smooth and protective surface. Mesothelial cells are squamous epithelial cells that secrete a fluid that lubricates the mesothelium. In simple cuboidal epithelium , the nucleus of the box-like cells appears round and is generally located near the center of the cell. These epithelia are active in the secretion and absorptions of molecules. Simple cuboidal epithelia are observed in the lining of the kidney tubules and in the ducts of glands. In simple columnar epithelium , the nucleus of the tall column-like cells tends to be elongated and located in the basal end of the cells. Like the cuboidal epithelia, this epithelium is active in the absorption and secretion of molecules. Simple columnar epithelium forms the lining of some sections of the digestive system and parts of the female reproductive tract. Ciliated columnar epithelium is composed of simple columnar epithelial cells with cilia on their apical surfaces. These epithelial cells are found in the lining of the fallopian tubes and parts of the respiratory system, where the beating of the cilia helps remove particulate matter. Pseudostratified columnar epithelium is a type of epithelium that appears to be stratified but instead consists of a single layer of irregularly shaped and differently sized columnar cells. In pseudostratified epithelium, nuclei of neighboring cells appear at different levels rather than clustered in the basal end. The arrangement gives the appearance of stratification; but in fact all the cells are in contact with the basal lamina, although some do not reach the apical surface. Pseudostratified columnar epithelium is found in the respiratory tract, where some of these cells have cilia. Both simple and pseudostratified columnar epithelia are heterogeneous epithelia because they include additional types of cells interspersed among the epithelial cells. For example, a goblet cell is a mucous-secreting unicellular “gland” interspersed between the columnar epithelial cells of mucous membranes ( Figure 4.7 ). Interactive Link View the University of Michigan WebScope to explore the tissue sample in greater detail. Stratified Epithelium A stratified epithelium consists of several stacked layers of cells. This epithelium protects against physical and chemical wear and tear. The stratified epithelium is named by the shape of the most apical layer of cells, closest to the free space. Stratified squamous epithelium is the most common type of stratified epithelium in the human body. The apical cells are squamous, whereas the basal layer contains either columnar or cuboidal cells. The top layer may be covered with dead cells filled with keratin. Mammalian skin is an example of this dry, keratinized, stratified squamous epithelium. The lining of the mouth cavity is an example of an unkeratinized, stratified squamous epithelium. Stratified cuboidal epithelium and stratified columnar epithelium can also be found in certain glands and ducts, but are uncommon in the human body. Another kind of stratified epithelium is transitional epithelium , so-called because of the gradual changes in the shapes of the apical cells as the bladder fills with urine. It is found only in the urinary system, specifically the ureters and urinary bladder. When the bladder is empty, this epithelium is convoluted and has cuboidal apical cells with convex, umbrella shaped, apical surfaces. As the bladder fills with urine, this epithelium loses its convolutions and the apical cells transition from cuboidal to squamous. It appears thicker and more multi-layered when the bladder is empty, and more stretched out and less stratified when the bladder is full and distended. Figure 4.8 summarizes the different categories of epithelial cell tissue cells. Interactive Link Watch this video to find out more about the anatomy of epithelial tissues. Where in the body would one find non-keratinizing stratified squamous epithelium? Glandular Epithelium A gland is a structure made up of one or more cells modified to synthesize and secrete chemical substances. Most glands consist of groups of epithelial cells. A gland can be classified as an endocrine gland , a ductless gland that releases secretions directly into surrounding tissues and fluids (endo- = “inside”), or an exocrine gland whose secretions leave through a duct that opens directly, or indirectly, to the external environment (exo- = “outside”). Endocrine Glands The secretions of endocrine glands are called hormones. Hormones are released into the interstitial fluid, diffused into the bloodstream, and delivered to targets, in other words, cells that have receptors to bind the hormones. The endocrine system is part of a major regulatory system coordinating the regulation and integration of body responses. A few examples of endocrine glands include the anterior pituitary, thymus, adrenal cortex, and gonads. Exocrine Glands Exocrine glands release their contents through a duct that leads to the epithelial surface. Mucous, sweat, saliva, and breast milk are all examples of secretions from exocrine glands. They are all discharged through tubular ducts. Secretions into the lumen of the gastrointestinal tract, technically outside of the body, are of the exocrine category. Glandular Structure Exocrine glands are classified as either unicellular or multicellular. The unicellular glands are scattered single cells, such as goblet cells, found in the mucous membranes of the small and large intestine. The multicellular exocrine glands known as serous glands develop from simple epithelium to form a secretory surface that secretes directly into an inner cavity. These glands line the internal cavities of the abdomen and chest and release their secretions directly into the cavities. Other multicellular exocrine glands release their contents through a tubular duct. The duct is single in a simple gland but in compound glands is divided into one or more branches ( Figure 4.9 ). In tubular glands, the ducts can be straight or coiled, whereas tubes that form pockets are alveolar (acinar), such as the exocrine portion of the pancreas. Combinations of tubes and pockets are known as tubuloalveolar (tubuloacinar) compound glands. In a branched gland, a duct is connected to more than one secretory group of cells. Methods and Types of Secretion Exocrine glands can be classified by their mode of secretion and the nature of the substances released, as well as by the structure of the glands and shape of ducts ( Figure 4.10 ). Merocrine secretion is the most common type of exocrine secretion. The secretions are enclosed in vesicles that move to the apical surface of the cell where the contents are released by exocytosis. For example, watery mucous containing the glycoprotein mucin, a lubricant that offers some pathogen protection is a merocrine secretion. The eccrine glands that produce and secrete sweat are another example. Apocrine secretion accumulates near the apical portion of the cell. That portion of the cell and its secretory contents pinch off from the cell and are released. Apocrine sweat glands in the axillary and genital areas release fatty secretions that local bacteria break down; this causes body odor. Both merocrine and apocrine glands continue to produce and secrete their contents with little damage caused to the cell because the nucleus and golgi regions remain intact after secretion. In contrast, the process of holocrine secretion involves the rupture and destruction of the entire gland cell. The cell accumulates its secretory products and releases them only when it bursts. New gland cells differentiate from cells in the surrounding tissue to replace those lost by secretion. The sebaceous glands that produce the oils on the skin and hair are holocrine glands/cells ( Figure 4.11 ). Glands are also named after the products they produce. The serous gland produces watery, blood-plasma-like secretions rich in enzymes such as alpha amylase, whereas the mucous gland releases watery to viscous products rich in the glycoprotein mucin. Both serous and mucous glands are common in the salivary glands of the mouth. Mixed exocrine glands contain both serous and mucous glands and release both types of secretions. 4.3 Connective Tissue Supports and Protects Learning Objectives By the end of this section, you will be able to: Identify and distinguish between the types of connective tissue: proper, supportive, and fluid Explain the functions of connective tissues As may be obvious from its name, one of the major functions of connective tissue is to connect tissues and organs. Unlike epithelial tissue, which is composed of cells closely packed with little or no extracellular space in between, connective tissue cells are dispersed in a matrix . The matrix usually includes a large amount of extracellular material produced by the connective tissue cells that are embedded within it. The matrix plays a major role in the functioning of this tissue. The major component of the matrix is a ground substance often crisscrossed by protein fibers. This ground substance is usually a fluid, but it can also be mineralized and solid, as in bones. Connective tissues come in a vast variety of forms, yet they typically have in common three characteristic components: cells, large amounts of amorphous ground substance, and protein fibers. The amount and structure of each component correlates with the function of the tissue, from the rigid ground substance in bones supporting the body to the inclusion of specialized cells; for example, a phagocytic cell that engulfs pathogens and also rids tissue of cellular debris. Functions of Connective Tissues Connective tissues perform many functions in the body, but most importantly, they support and connect other tissues; from the connective tissue sheath that surrounds muscle cells, to the tendons that attach muscles to bones, and to the skeleton that supports the positions of the body. Protection is another major function of connective tissue, in the form of fibrous capsules and bones that protect delicate organs and, of course, the skeletal system. Specialized cells in connective tissue defend the body from microorganisms that enter the body. Transport of fluid, nutrients, waste, and chemical messengers is ensured by specialized fluid connective tissues, such as blood and lymph. Adipose cells store surplus energy in the form of fat and contribute to the thermal insulation of the body. Embryonic Connective Tissue All connective tissues derive from the mesodermal layer of the embryo (see Figure 4.3 ). The first connective tissue to develop in the embryo is mesenchyme , the stem cell line from which all connective tissues are later derived. Clusters of mesenchymal cells are scattered throughout adult tissue and supply the cells needed for replacement and repair after a connective tissue injury. A second type of embryonic connective tissue forms in the umbilical cord, called mucous connective tissue or Wharton’s jelly. This tissue is no longer present after birth, leaving only scattered mesenchymal cells throughout the body. Classification of Connective Tissues The three broad categories of connective tissue are classified according to the characteristics of their ground substance and the types of fibers found within the matrix ( Table 4.1 ). Connective tissue proper includes loose connective tissue and dense connective tissue . Both tissues have a variety of cell types and protein fibers suspended in a viscous ground substance. Dense connective tissue is reinforced by bundles of fibers that provide tensile strength, elasticity, and protection. In loose connective tissue, the fibers are loosely organized, leaving large spaces in between. Supportive connective tissue —bone and cartilage—provide structure and strength to the body and protect soft tissues. A few distinct cell types and densely packed fibers in a matrix characterize these tissues. In bone, the matrix is rigid and described as calcified because of the deposited calcium salts. In fluid connective tissue , in other words, lymph and blood, various specialized cells circulate in a watery fluid containing salts, nutrients, and dissolved proteins. Connective Tissue Examples Connective tissue proper Supportive connective tissue Fluid connective tissue Loose connective tissue Areolar Adipose Reticular Cartilage Hyaline Fibrocartilage Elastic Blood Dense connective tissue Regular elastic Irregular elastic Bones Compact bone Cancellous bone Lymph Table 4.1 Connective Tissue Proper Fibroblasts are present in all connective tissue proper ( Figure 4.12 ). Fibrocytes, adipocytes, and mesenchymal cells are fixed cells, which means they remain within the connective tissue. Other cells move in and out of the connective tissue in response to chemical signals. Macrophages, mast cells, lymphocytes, plasma cells, and phagocytic cells are found in connective tissue proper but are actually part of the immune system protecting the body. Cell Types The most abundant cell in connective tissue proper is the fibroblast . Polysaccharides and proteins secreted by fibroblasts combine with extra-cellular fluids to produce a viscous ground substance that, with embedded fibrous proteins, forms the extra-cellular matrix. As you might expect, a fibrocyte , a less active form of fibroblast, is the second most common cell type in connective tissue proper. Adipocytes are cells that store lipids as droplets that fill most of the cytoplasm. There are two basic types of adipocytes: white and brown. The brown adipocytes store lipids as many droplets, and have high metabolic activity. In contrast, white fat adipocytes store lipids as a single large drop and are metabolically less active. Their effectiveness at storing large amounts of fat is witnessed in obese individuals. The number and type of adipocytes depends on the tissue and location, and vary among individuals in the population. The mesenchymal cell is a multipotent adult stem cell. These cells can differentiate into any type of connective tissue cells needed for repair and healing of damaged tissue. The macrophage cell is a large cell derived from a monocyte, a type of blood cell, which enters the connective tissue matrix from the blood vessels. The macrophage cells are an essential component of the immune system, which is the body’s defense against potential pathogens and degraded host cells. When stimulated, macrophages release cytokines, small proteins that act as chemical messengers. Cytokines recruit other cells of the immune system to infected sites and stimulate their activities. Roaming, or free, macrophages move rapidly by amoeboid movement, engulfing infectious agents and cellular debris. In contrast, fixed macrophages are permanent residents of their tissues. The mast cell, found in connective tissue proper, has many cytoplasmic granules. These granules contain the chemical signals histamine and heparin. When irritated or damaged, mast cells release histamine, an inflammatory mediator, which causes vasodilation and increased blood flow at a site of injury or infection, along with itching, swelling, and redness you recognize as an allergic response. Like blood cells, mast cells are derived from hematopoietic stem cells and are part of the immune system. Connective Tissue Fibers and Ground Substance Three main types of fibers are secreted by fibroblasts: collagen fibers, elastic fibers, and reticular fibers. Collagen fiber is made from fibrous protein subunits linked together to form a long and straight fiber. Collagen fibers, while flexible, have great tensile strength, resist stretching, and give ligaments and tendons their characteristic resilience and strength. These fibers hold connective tissues together, even during the movement of the body. Elastic fiber contains the protein elastin along with lesser amounts of other proteins and glycoproteins. The main property of elastin is that after being stretched or compressed, it will return to its original shape. Elastic fibers are prominent in elastic tissues found in skin and the elastic ligaments of the vertebral column. Reticular fiber is also formed from the same protein subunits as collagen fibers; however, these fibers remain narrow and are arrayed in a branching network. They are found throughout the body, but are most abundant in the reticular tissue of soft organs, such as liver and spleen, where they anchor and provide structural support to the parenchyma (the functional cells, blood vessels, and nerves of the organ). All of these fiber types are embedded in ground substance. Secreted by fibroblasts, ground substance is made of polysaccharides, specifically hyaluronic acid, and proteins. These combine to form a proteoglycan with a protein core and polysaccharide branches. The proteoglycan attracts and traps available moisture forming the clear, viscous, colorless matrix you now know as ground substance. Loose Connective Tissue Loose connective tissue is found between many organs where it acts both to absorb shock and bind tissues together. It allows water, salts, and various nutrients to diffuse through to adjacent or imbedded cells and tissues. Adipose tissue consists mostly of fat storage cells, with little extracellular matrix ( Figure 4.13 ). A large number of capillaries allow rapid storage and mobilization of lipid molecules. White adipose tissue is most abundant. It can appear yellow and owes its color to carotene and related pigments from plant food. White fat contributes mostly to lipid storage and can serve as insulation from cold temperatures and mechanical injuries. White adipose tissue can be found protecting the kidneys and cushioning the back of the eye. Brown adipose tissue is more common in infants, hence the term “baby fat.” In adults, there is a reduced amount of brown fat and it is found mainly in the neck and clavicular regions of the body. The many mitochondria in the cytoplasm of brown adipose tissue help explain its efficiency at metabolizing stored fat. Brown adipose tissue is thermogenic, meaning that as it breaks down fats, it releases metabolic heat, rather than producing adenosine triphosphate (ATP), a key molecule used in metabolism. Areolar tissue shows little specialization. It contains all the cell types and fibers previously described and is distributed in a random, web-like fashion. It fills the spaces between muscle fibers, surrounds blood and lymph vessels, and supports organs in the abdominal cavity. Areolar tissue underlies most epithelia and represents the connective tissue component of epithelial membranes, which are described further in a later section. Reticular tissue is a mesh-like, supportive framework for soft organs such as lymphatic tissue, the spleen, and the liver ( Figure 4.14 ). Reticular cells produce the reticular fibers that form the network onto which other cells attach. It derives its name from the Latin reticulus , which means “little net.” Dense Connective Tissue Dense connective tissue contains more collagen fibers than does loose connective tissue. As a consequence, it displays greater resistance to stretching. There are two major categories of dense connective tissue: regular and irregular. Dense regular connective tissue fibers are parallel to each other, enhancing tensile strength and resistance to stretching in the direction of the fiber orientations. Ligaments and tendons are made of dense regular connective tissue, but in ligaments not all fibers are parallel. Dense regular elastic tissue contains elastin fibers in addition to collagen fibers, which allows the ligament to return to its original length after stretching. The ligaments in the vocal folds and between the vertebrae in the vertebral column are elastic. In dense irregular connective tissue, the direction of fibers is random. This arrangement gives the tissue greater strength in all directions and less strength in one particular direction. In some tissues, fibers crisscross and form a mesh. In other tissues, stretching in several directions is achieved by alternating layers where fibers run in the same orientation in each layer, and it is the layers themselves that are stacked at an angle. The dermis of the skin is an example of dense irregular connective tissue rich in collagen fibers. Dense irregular elastic tissues give arterial walls the strength and the ability to regain original shape after stretching ( Figure 4.15 ). Disorders of the... Connective Tissue: Tendinitis Your opponent stands ready as you prepare to hit the serve, but you are confident that you will smash the ball past your opponent. As you toss the ball high in the air, a burning pain shoots across your wrist and you drop the tennis racket. That dull ache in the wrist that you ignored through the summer is now an unbearable pain. The game is over for now. After examining your swollen wrist, the doctor in the emergency room announces that you have developed wrist tendinitis. She recommends icing the tender area, taking non-steroidal anti-inflammatory medication to ease the pain and to reduce swelling, and complete rest for a few weeks. She interrupts your protests that you cannot stop playing. She issues a stern warning about the risk of aggravating the condition and the possibility of surgery. She consoles you by mentioning that well known tennis players such as Venus and Serena Williams and Rafael Nadal have also suffered from tendinitis related injuries. What is tendinitis and how did it happen? Tendinitis is the inflammation of a tendon, the thick band of fibrous connective tissue that attaches a muscle to a bone. The condition causes pain and tenderness in the area around a joint. On rare occasions, a sudden serious injury will cause tendinitis. Most often, the condition results from repetitive motions over time that strain the tendons needed to perform the tasks. Persons whose jobs and hobbies involve performing the same movements over and over again are often at the greatest risk of tendinitis. You hear of tennis and golfer’s elbow, jumper's knee, and swimmer’s shoulder. In all cases, overuse of the joint causes a microtrauma that initiates the inflammatory response. Tendinitis is routinely diagnosed through a clinical examination. In case of severe pain, X-rays can be examined to rule out the possibility of a bone injury. Severe cases of tendinitis can even tear loose a tendon. Surgical repair of a tendon is painful. Connective tissue in the tendon does not have abundant blood supply and heals slowly. While older adults are at risk for tendinitis because the elasticity of tendon tissue decreases with age, active people of all ages can develop tendinitis. Young athletes, dancers, and computer operators; anyone who performs the same movements constantly is at risk for tendinitis. Although repetitive motions are unavoidable in many activities and may lead to tendinitis, precautions can be taken that can lessen the probability of developing tendinitis. For active individuals, stretches before exercising and cross training or changing exercises are recommended. For the passionate athlete, it may be time to take some lessons to improve technique. All of the preventive measures aim to increase the strength of the tendon and decrease the stress put on it. With proper rest and managed care, you will be back on the court to hit that slice-spin serve over the net. Interactive Link Watch this animation to learn more about tendonitis, a painful condition caused by swollen or injured tendons. Supportive Connective Tissues Two major forms of supportive connective tissue, cartilage and bone, allow the body to maintain its posture and protect internal organs. Cartilage The distinctive appearance of cartilage is due to polysaccharides called chondroitin sulfates, which bind with ground substance proteins to form proteoglycans. Embedded within the cartilage matrix are chondrocytes , or cartilage cells, and the space they occupy are called lacunae (singular = lacuna). A layer of dense irregular connective tissue, the perichondrium, encapsulates the cartilage. Cartilaginous tissue is avascular, thus all nutrients need to diffuse through the matrix to reach the chondrocytes. This is a factor contributing to the very slow healing of cartilaginous tissues. The three main types of cartilage tissue are hyaline cartilage, fibrocartilage, and elastic cartilage ( Figure 4.16 ). Hyaline cartilage , the most common type of cartilage in the body, consists of short and dispersed collagen fibers and contains large amounts of proteoglycans. Under the microscope, tissue samples appear clear. The surface of hyaline cartilage is smooth. Both strong and flexible, it is found in the rib cage and nose and covers bones where they meet to form moveable joints. It makes up a template of the embryonic skeleton before bone formation. A plate of hyaline cartilage at the ends of bone allows continued growth until adulthood. Fibrocartilage is tough because it has thick bundles of collagen fibers dispersed through its matrix. Menisci in the knee joint and the intervertebral discs are examples of fibrocartilage. Elastic cartilage contains elastic fibers as well as collagen and proteoglycans. This tissue gives rigid support as well as elasticity. Tug gently at your ear lobes, and notice that the lobes return to their initial shape. The external ear contains elastic cartilage. Bone Bone is the hardest connective tissue. It provides protection to internal organs and supports the body. Bone’s rigid extracellular matrix contains mostly collagen fibers embedded in a mineralized ground substance containing hydroxyapatite, a form of calcium phosphate. Both components of the matrix, organic and inorganic, contribute to the unusual properties of bone. Without collagen, bones would be brittle and shatter easily. Without mineral crystals, bones would flex and provide little support. Osteocytes, bone cells like chondrocytes, are located within lacunae. The histology of transverse tissue from long bone shows a typical arrangement of osteocytes in concentric circles around a central canal. Bone is a highly vascularized tissue. Unlike cartilage, bone tissue can recover from injuries in a relatively short time. Cancellous bone looks like a sponge under the microscope and contains empty spaces between trabeculae, or arches of bone proper. It is lighter than compact bone and found in the interior of some bones and at the end of long bones. Compact bone is solid and has greater structural strength. Fluid Connective Tissue Blood and lymph are fluid connective tissues. Cells circulate in a liquid extracellular matrix. The formed elements circulating in blood are all derived from hematopoietic stem cells located in bone marrow ( Figure 4.17 ). Erythrocytes, red blood cells, transport oxygen and some carbon dioxide. Leukocytes, white blood cells, are responsible for defending against potentially harmful microorganisms or molecules. Platelets are cell fragments involved in blood clotting. Some white blood cells have the ability to cross the endothelial layer that lines blood vessels and enter adjacent tissues. Nutrients, salts, and wastes are dissolved in the liquid matrix and transported through the body. Lymph contains a liquid matrix and white blood cells. Lymphatic capillaries are extremely permeable, allowing larger molecules and excess fluid from interstitial spaces to enter the lymphatic vessels. Lymph drains into blood vessels, delivering molecules to the blood that could not otherwise directly enter the bloodstream. In this way, specialized lymphatic capillaries transport absorbed fats away from the intestine and deliver these molecules to the blood. Interactive Link View the University of Michigan Webscope to explore the tissue sample in greater detail. Interactive Link Visit this link to test your connective tissue knowledge with this 10-question quiz. Can you name the 10 tissue types shown in the histology slides? 4.4 Muscle Tissue and Motion Learning Objectives By the end of this section, you will be able to: Identify the three types of muscle tissue Compare and contrast the functions of each muscle tissue type Explain how muscle tissue can enable motion Muscle tissue is characterized by properties that allow movement. Muscle cells are excitable; they respond to a stimulus. They are contractile, meaning they can shorten and generate a pulling force. When attached between two movable objects, in other words, bones, contractions of the muscles cause the bones to move. Some muscle movement is voluntary, which means it is under conscious control. For example, a person decides to open a book and read a chapter on anatomy. Other movements are involuntary, meaning they are not under conscious control, such as the contraction of your pupil in bright light. Muscle tissue is classified into three types according to structure and function: skeletal, cardiac, and smooth ( Table 4.2 ). Comparison of Structure and Properties of Muscle Tissue Types Tissue Histology Function Location Skeletal Long cylindrical fiber, striated, many peripherally located nuclei Voluntary movement, produces heat, protects organs Attached to bones and around entrance points to body (e.g., mouth, anus) Cardiac Short, branched, striated, single central nucleus Contracts to pump blood Heart Smooth Short, spindle-shaped, no evident striation, single nucleus in each fiber Involuntary movement, moves food, involuntary control of respiration, moves secretions, regulates flow of blood in arteries by contraction Walls of major organs and passageways Table 4.2 Skeletal muscle is attached to bones and its contraction makes possible locomotion, facial expressions, posture, and other voluntary movements of the body. Forty percent of your body mass is made up of skeletal muscle. Skeletal muscles generate heat as a byproduct of their contraction and thus participate in thermal homeostasis. Shivering is an involuntary contraction of skeletal muscles in response to perceived lower than normal body temperature. The muscle cell, or myocyte , develops from myoblasts derived from the mesoderm. Myocytes and their numbers remain relatively constant throughout life. Skeletal muscle tissue is arranged in bundles surrounded by connective tissue. Under the light microscope, muscle cells appear striated with many nuclei squeezed along the membranes. The striation is due to the regular alternation of the contractile proteins actin and myosin, along with the structural proteins that couple the contractile proteins to connective tissues. The cells are multinucleated as a result of the fusion of the many myoblasts that fuse to form each long muscle fiber. Cardiac muscle forms the contractile walls of the heart. The cells of cardiac muscle, known as cardiomyocytes, also appear striated under the microscope. Unlike skeletal muscle fibers, cardiomyocytes are single cells typically with a single centrally located nucleus. A principal characteristic of cardiomyocytes is that they contract on their own intrinsic rhythms without any external stimulation. Cardiomyocyte attach to one another with specialized cell junctions called intercalated discs. Intercalated discs have both anchoring junctions and gap junctions. Attached cells form long, branching cardiac muscle fibers that are, essentially, a mechanical and electrochemical syncytium allowing the cells to synchronize their actions. The cardiac muscle pumps blood through the body and is under involuntary control. The attachment junctions hold adjacent cells together across the dynamic pressures changes of the cardiac cycle. Smooth muscle tissue contraction is responsible for involuntary movements in the internal organs. It forms the contractile component of the digestive, urinary, and reproductive systems as well as the airways and arteries. Each cell is spindle shaped with a single nucleus and no visible striations ( Figure 4.18 ). Interactive Link Watch this video to learn more about muscle tissue. In looking through a microscope how could you distinguish skeletal muscle tissue from smooth muscle? 4.5 Nervous Tissue Mediates Perception and Response Learning Objectives By the end of this section, you will be able to: Identify the classes of cells that make up nervous tissue Discuss how nervous tissue mediates perception and response Nervous tissue is characterized as being excitable and capable of sending and receiving electrochemical signals that provide the body with information. Two main classes of cells make up nervous tissue: the neuron and neuroglia ( Figure 4.19 ). Neurons propagate information via electrochemical impulses, called action potentials, which are biochemically linked to the release of chemical signals. Neuroglia play an essential role in supporting neurons and modulating their information propagation. Interactive Link Follow this link to learn more about nervous tissue. What are the main parts of a nerve cell? Neurons display distinctive morphology, well suited to their role as conducting cells, with three main parts. The cell body includes most of the cytoplasm, the organelles, and the nucleus. Dendrites branch off the cell body and appear as thin extensions. A long “tail,” the axon, extends from the neuron body and can be wrapped in an insulating layer known as myelin , which is formed by accessory cells. The synapse is the gap between nerve cells, or between a nerve cell and its target, for example, a muscle or a gland, across which the impulse is transmitted by chemical compounds known as neurotransmitters. Neurons categorized as multipolar neurons have several dendrites and a single prominent axon. Bipolar neurons possess a single dendrite and axon with the cell body, while unipolar neurons have only a single process extending out from the cell body, which divides into a functional dendrite and into a functional axon. When a neuron is sufficiently stimulated, it generates an action potential that propagates down the axon towards the synapse. If enough neurotransmitters are released at the synapse to stimulate the next neuron or target, a response is generated. The second class of neural cells comprises the neuroglia or glial cells, which have been characterized as having a simple support role. The word “glia” comes from the Greek word for glue. Recent research is shedding light on the more complex role of neuroglia in the function of the brain and nervous system. Astrocyte cells, named for their distinctive star shape, are abundant in the central nervous system. The astrocytes have many functions, including regulation of ion concentration in the intercellular space, uptake and/or breakdown of some neurotransmitters, and formation of the blood-brain barrier, the membrane that separates the circulatory system from the brain. Microglia protect the nervous system against infection but are not nervous tissue because they are related to macrophages. Oligodendrocyte cells produce myelin in the central nervous system (brain and spinal cord) while the Schwann cell produces myelin in the peripheral nervous system ( Figure 4.20 ). 4.6 Tissue Injury and Aging Learning Objectives By the end of this section, you will be able to: Identify the cardinal signs of inflammation List the body’s response to tissue injury Explain the process of tissue repair Discuss the progressive impact of aging on tissue Describe cancerous mutations’ effect on tissue Tissues of all types are vulnerable to injury and, inevitably, aging. In the former case, understanding how tissues respond to damage can guide strategies to aid repair. In the latter case, understanding the impact of aging can help in the search for ways to diminish its effects. Tissue Injury and Repair Inflammation is the standard, initial response of the body to injury. Whether biological, chemical, physical, or radiation burns, all injuries lead to the same sequence of physiological events. Inflammation limits the extent of injury, partially or fully eliminates the cause of injury, and initiates repair and regeneration of damaged tissue. Necrosis , or accidental cell death, causes inflammation. Apoptosis is programmed cell death, a normal step-by-step process that destroys cells no longer needed by the body. By mechanisms still under investigation, apoptosis does not initiate the inflammatory response. Acute inflammation resolves over time by the healing of tissue. If inflammation persists, it becomes chronic and leads to diseased conditions. Arthritis and tuberculosis are examples of chronic inflammation. The suffix “-itis” denotes inflammation of a specific organ or type, for example, peritonitis is the inflammation of the peritoneum, and meningitis refers to the inflammation of the meninges, the tough membranes that surround the central nervous system The four cardinal signs of inflammation—redness, swelling, pain, and local heat—were first recorded in antiquity. Cornelius Celsus is credited with documenting these signs during the days of the Roman Empire, as early as the first century AD. A fifth sign, loss of function, may also accompany inflammation. Upon tissue injury, damaged cells release inflammatory chemical signals that evoke local vasodilation , the widening of the blood vessels. Increased blood flow results in apparent redness and heat. In response to injury, mast cells present in tissue degranulate, releasing the potent vasodilator histamine . Increased blood flow and inflammatory mediators recruit white blood cells to the site of inflammation. The endothelium lining the local blood vessel becomes “leaky” under the influence of histamine and other inflammatory mediators allowing neutrophils, macrophages, and fluid to move from the blood into the interstitial tissue spaces. The excess liquid in tissue causes swelling, more properly called edema. The swollen tissues squeezing pain receptors cause the sensation of pain. Prostaglandins released from injured cells also activate pain neurons. Non-steroidal anti-inflammatory drugs (NSAIDs) reduce pain because they inhibit the synthesis of prostaglandins. High levels of NSAIDs reduce inflammation. Antihistamines decrease allergies by blocking histamine receptors and as a result the histamine response. After containment of an injury, the tissue repair phase starts with removal of toxins and waste products. Clotting (coagulation) reduces blood loss from damaged blood vessels and forms a network of fibrin proteins that trap blood cells and bind the edges of the wound together. A scab forms when the clot dries, reducing the risk of infection. Sometimes a mixture of dead leukocytes and fluid called pus accumulates in the wound. As healing progresses, fibroblasts from the surrounding connective tissues replace the collagen and extracellular material lost by the injury. Angiogenesis, the growth of new blood vessels, results in vascularization of the new tissue known as granulation tissue. The clot retracts pulling the edges of the wound together, and it slowly dissolves as the tissue is repaired. When a large amount of granulation tissue forms and capillaries disappear, a pale scar is often visible in the healed area. A primary union describes the healing of a wound where the edges are close together. When there is a gaping wound, it takes longer to refill the area with cells and collagen. The process called secondary union occurs as the edges of the wound are pulled together by what is called wound contraction . When a wound is more than one quarter of an inch deep, sutures (stitches) are recommended to promote a primary union and avoid the formation of a disfiguring scar. Regeneration is the addition of new cells of the same type as the ones that were injured ( Figure 4.21 ). Interactive Link Watch this video to see a hand heal. Over what period of time do you think these images were taken? Tissue and Aging According to poet Ralph Waldo Emerson, “The surest poison is time.” In fact, biology confirms that many functions of the body decline with age. All the cells, tissues, and organs are affected by senescence, with noticeable variability between individuals owing to different genetic makeup and lifestyles. The outward signs of aging are easily recognizable. The skin and other tissues become thinner and drier, reducing their elasticity, contributing to wrinkles and high blood pressure. Hair turns gray because follicles produce less melanin, the brown pigment of hair and the iris of the eye. The face looks flabby because elastic and collagen fibers decrease in connective tissue and muscle tone is lost. Glasses and hearing aids may become parts of life as the senses slowly deteriorate, all due to reduced elasticity. Overall height decreases as the bones lose calcium and other minerals. With age, fluid decreases in the fibrous cartilage disks intercalated between the vertebrae in the spine. Joints lose cartilage and stiffen. Many tissues, including those in muscles, lose mass through a process called atrophy . Lumps and rigidity become more widespread. As a consequence, the passageways, blood vessels, and airways become more rigid. The brain and spinal cord lose mass. Nerves do not transmit impulses with the same speed and frequency as in the past. Some loss of thought clarity and memory can accompany aging. More severe problems are not necessarily associated with the aging process and may be symptoms of underlying illness. As exterior signs of aging increase, so do the interior signs, which are not as noticeable. The incidence of heart diseases, respiratory syndromes, and type 2 diabetes increases with age, though these are not necessarily age-dependent effects. Wound healing is slower in the elderly, accompanied by a higher frequency of infection as the capacity of the immune system to fend off pathogen declines. Aging is also apparent at the cellular level because all cells experience changes with aging. Telomeres, regions of the chromosomes necessary for cell division, shorten each time cells divide. As they do, cells are less able to divide and regenerate. Because of alterations in cell membranes, transport of oxygen and nutrients into the cell and removal of carbon dioxide and waste products from the cell are not as efficient in the elderly. Cells may begin to function abnormally, which may lead to diseases associated with aging, including arthritis, memory issues, and some cancers. The progressive impact of aging on the body varies considerably among individuals, but Studies indicate, however, that exercise and healthy lifestyle choices can slow down the deterioration of the body that comes with old age. Homeostatic Imbalances Tissues and Cancer Cancer is a generic term for many diseases in which cells escape regulatory signals. Uncontrolled growth, invasion into adjacent tissues, and colonization of other organs, if not treated early enough, are its hallmarks. Health suffers when tumors “rob” blood supply from the “normal” organs. A mutation is defined as a permanent change in the DNA of a cell. Epigenetic modifications, changes that do not affect the code of the DNA but alter how the DNA is decoded, are also known to generate abnormal cells. Alterations in the genetic material may be caused by environmental agents, infectious agents, or errors in the replication of DNA that accumulate with age. Many mutations do not cause any noticeable change in the functions of a cell. However, if the modification affects key proteins that have an impact on the cell’s ability to proliferate in an orderly fashion, the cell starts to divide abnormally. As changes in cells accumulate, they lose their ability to form regular tissues. A tumor, a mass of cells displaying abnormal architecture, forms in the tissue. Many tumors are benign, meaning they do not metastasize nor cause disease. A tumor becomes malignant, or cancerous, when it breaches the confines of its tissue, promotes angiogenesis, attracts the growth of capillaries, and metastasizes to other organs ( Figure 4.22 ). The specific names of cancers reflect the tissue of origin. Cancers derived from epithelial cells are referred to as carcinomas. Cancer in myeloid tissue or blood cells form myelomas. Leukemias are cancers of white blood cells, whereas sarcomas derive from connective tissue. Cells in tumors differ both in structure and function. Some cells, called cancer stem cells, appear to be a subtype of cell responsible for uncontrolled growth. Recent research shows that contrary to what was previously assumed, tumors are not disorganized masses of cells, but have their own structures. Interactive Link Watch this video to learn more about tumors. What is a tumor? Cancer treatments vary depending on the disease’s type and stage. Traditional approaches, including surgery, radiation, chemotherapy, and hormonal therapy, aim to remove or kill rapidly dividing cancer cells, but these strategies have their limitations. Depending on a tumor’s location, for example, cancer surgeons may be unable to remove it. Radiation and chemotherapy are difficult, and it is often impossible to target only the cancer cells. The treatments inevitably destroy healthy tissue as well. To address this, researchers are working on pharmaceuticals that can target specific proteins implicated in cancer-associated molecular pathways.
u.s._history
Summary 4.1 Charles II and the Restoration Colonies After the English Civil War and interregnum, England began to fashion a stronger and larger empire in North America. In addition to wresting control of New York and New Jersey from the Dutch, Charles II established the Carolinas and Pennsylvania as proprietary colonies. Each of these colonies added immensely to the Empire, supplying goods not produced in England, such as rice and indigo. The Restoration colonies also contributed to the rise in population in English America as many thousands of Europeans made their way to the colonies. Their numbers were further augmented by the forced migration of enslaved Africans. Starting in 1651, England pursued mercantilist policies through a series of Navigation Acts designed to make the most of England’s overseas possessions. Nonetheless, without proper enforcement of Parliament’s acts and with nothing to prevent colonial traders from commanding their own fleets of ships, the Navigation Acts did not control trade as intended. 4.2 The Glorious Revolution and the English Empire The threat of a Catholic absolute monarchy prompted not only the overthrow of James II but also the adoption of laws and policies that changed English government. The Glorious Revolution restored a Protestant monarchy and at the same time limited its power by means of the 1689 Bill of Rights. Those who lived through the events preserved the memory of the Glorious Revolution and the defense of liberty that it represented. Meanwhile, thinkers such as John Locke provided new models and inspirations for the evolving concept of government. 4.3 An Empire of Slavery and the Consumer Revolution The seventeenth and eighteenth centuries saw the expansion of slavery in the American colonies from South Carolina to Boston. The institution of slavery created a false sense of superiority in Whites, while simultaneously fueling fears of slave revolt. White response to such revolts, or even the threat of them, led to gross overreactions and further constraints on enslaved people’s activities. The development of the Atlantic economy also allowed colonists access to more British goods than ever before. The buying habits of both commoners and the rising colonial gentry fueled the consumer revolution, creating even stronger ties with Great Britain by means of a shared community of taste and ideas. 4.4 Great Awakening and Enlightenment The eighteenth century saw a host of social, religious, and intellectual changes across the British Empire. While the Great Awakening emphasized vigorously emotional religiosity, the Enlightenment promoted the power of reason and scientific observation. Both movements had lasting impacts on the colonies. The beliefs of the New Lights of the First Great Awakening competed with the religions of the first colonists, and the religious fervor in Great Britain and her North American colonies bound the eighteenth-century British Atlantic together in a shared, common experience. The British colonist Benjamin Franklin gained fame on both sides of the Atlantic as a printer, publisher, and scientist. He embodied Enlightenment ideals in the British Atlantic with his scientific experiments and philanthropic endeavors. Enlightenment principles even guided the founding of the colony of Georgia, although those principles could not stand up to the realities of colonial life, and slavery soon took hold in the colony. 4.5 Wars for Empire From 1688 to 1763, Great Britain engaged in almost continuous power struggles with France and Spain. Most of these conflicts originated in Europe, but their engagements spilled over into the colonies. For almost eighty years, Great Britain and France fought for control of eastern North America. During most of that time, neither force was able to win a decisive victory, though each side saw occasional successes with the crucial help of native peoples. It was not until halfway through the French and Indian War (1754–1763), when Great Britain swelled its troops with more volunteers and native allies, that the balance of power shifted toward the British. With the 1763 Treaty of Paris, New France was eliminated, and Great Britain gained control of all the lands north of Florida and east of the Mississippi. British subjects on both sides of the Atlantic rejoiced.
Chapter Outline 4.1 Charles II and the Restoration Colonies 4.2 The Glorious Revolution and the English Empire 4.3 An Empire of Slavery and the Consumer Revolution 4.4 Great Awakening and Enlightenment 4.5 Wars for Empire Introduction The eighteenth century witnessed the birth of Great Britain (after the union of England and Scotland in 1707) and the expansion of the British Empire. By the mid-1700s, Great Britain had developed into a commercial and military powerhouse; its economic sway ranged from India, where the British East India Company had gained control over both trade and territory, to the West African coast, where British slave traders predominated, and to the British West Indies, whose lucrative sugar plantations, especially in Barbados and Jamaica, provided windfall profits for British planters. Meanwhile, the population rose dramatically in Britain’s North American colonies. In the early 1700s the population in the colonies had reached 250,000. By 1750, however, over a million British migrants and enslaved Africans had established a near-continuous zone of settlement on the Atlantic coast from Maine to Georgia. During this period, the ties between Great Britain and the American colonies only grew stronger. Anglo-American colonists considered themselves part of the British Empire in all ways: politically, militarily, religiously (as Protestants), intellectually, and racially. The portrait of the Royall family ( Figure 4.1 ) exemplifies the colonial American gentry of the eighteenth century. Successful and well-to-do, they display fashions, hairstyles, and furnishings that all speak to their identity as proud and loyal British subjects.
[ { "answer": { "ans_choice": 2, "ans_text": "C" }, "bloom": null, "hl_context": "Though Cromwell enjoyed widespread popularity at first , over time he appeared to many in England to be taking on the powers of a military dictator . Dissatisfaction with Cromwell grew . When he died in 1658 and control passed to his son Richard , who lacked the political skills of his father , a majority of the English people feared an alternate hereditary monarchy in the making . They had had enough and asked Charles II to be king . <hl> In 1660 , they welcomed the son of the executed king Charles I back to the throne to resume the English monarchy and bring the interregnum to an end ( Figure 4.3 ) . <hl> <hl> The return of Charles II is known as the Restoration . <hl> <hl> When Charles II ascended the throne in 1660 , English subjects on both sides of the Atlantic celebrated the restoration of the English monarchy after a decade of living without a king as a result of the English Civil Wars . <hl> Charles II lost little time in strengthening England ’ s global power . From the 1660s to the 1680s , Charles II added more possessions to England ’ s North American holdings by establishing the Restoration colonies of New York and New Jersey ( taking these areas from the Dutch ) as well as Pennsylvania and the Carolinas . In order to reap the greatest economic benefit from England ’ s overseas possessions , Charles II enacted the mercantilist Navigation Acts , although many colonial merchants ignored them because enforcement remained lax .", "hl_sentences": "In 1660 , they welcomed the son of the executed king Charles I back to the throne to resume the English monarchy and bring the interregnum to an end ( Figure 4.3 ) . The return of Charles II is known as the Restoration . When Charles II ascended the throne in 1660 , English subjects on both sides of the Atlantic celebrated the restoration of the English monarchy after a decade of living without a king as a result of the English Civil Wars .", "question": { "cloze_format": "The term \"Restoration\" refers to ___.", "normal_format": "To what does the term “Restoration” refer?", "question_choices": [ "the restoration of New York to English power", "the restoration of Catholicism as the official religion of England", "the restoration of Charles II to the English throne", "the restoration of Parliamentary power in England" ], "question_id": "fs-idm22658320", "question_text": "To what does the term “Restoration” refer?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 0, "ans_text": "Quakerism" }, "bloom": null, "hl_context": "The English crown persecuted Quakers in England , and colonial governments were equally harsh ; Massachusetts even executed several early Quakers who had gone to proselytize there . <hl> To avoid such persecution , Quakers and their families at first created a community on the sugar island of Barbados . <hl> <hl> Soon after its founding , however , Pennsylvania became the destination of choice . <hl> Quakers flocked to Pennsylvania as well as New Jersey , where they could preach and practice their religion in peace . Unlike New England , whose official religion was Puritanism , Pennsylvania did not establish an official church . Indeed , the colony allowed a degree of religious tolerance found nowhere else in English America . To help encourage immigration to his colony , Penn promised fifty acres of land to people who agreed to come to Pennsylvania and completed their term of service . Not surprisingly , those seeking a better life came in large numbers , so much so that Pennsylvania relied on indentured servants more than any other colony .", "hl_sentences": "To avoid such persecution , Quakers and their families at first created a community on the sugar island of Barbados . Soon after its founding , however , Pennsylvania became the destination of choice .", "question": { "cloze_format": "___ was the predominant religion in Pennsylvania.", "normal_format": "What was the predominant religion in Pennsylvania?", "question_choices": [ "Quakerism", "Puritanism", "Catholicism", "Protestantism" ], "question_id": "fs-idm6272400", "question_text": "What was the predominant religion in Pennsylvania?" }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 3, "ans_text": "that he would institute a Catholic absolute monarchy" }, "bloom": null, "hl_context": "King James II ( Figure 4.7 ) , the second son of Charles I , ascended the English throne in 1685 on the death of his brother , Charles II . James then worked to model his rule on the reign of the French Catholic King Louis XIV , his cousin . This meant centralizing English political strength around the throne , giving the monarchy absolute power . Also like Louis XIV , James II practiced a strict and intolerant form of Roman Catholicism after he converted from Protestantism in the late 1660s . He had a Catholic wife , and when they had a son , the potential for a Catholic heir to the English throne became a threat to English Protestants . James also worked to modernize the English army and navy . The fact that the king kept a standing army in times of peace greatly alarmed the English , who believed that such a force would be used to crush their liberty . <hl> As James ’ s strength grew , his opponents feared their king would turn England into a Catholic monarchy with absolute power over her people . <hl> <hl> During the brief rule of King James II , many in England feared the imposition of a Catholic absolute monarchy by the man who modeled his rule on that of his French Catholic cousin , Louis XIV . <hl> Opposition to James II , spearheaded by the English Whig party , overthrew the king in the Glorious Revolution of 1688 – 1689 . This paved the way for the Protestant reign of William of Orange and his wife Mary ( James ’ s Protestant daughter ) .", "hl_sentences": "As James ’ s strength grew , his opponents feared their king would turn England into a Catholic monarchy with absolute power over her people . During the brief rule of King James II , many in England feared the imposition of a Catholic absolute monarchy by the man who modeled his rule on that of his French Catholic cousin , Louis XIV .", "question": { "cloze_format": "Those in England and het colonies maintained a concern about James II ____.", "normal_format": "Which of the following represents a concern that those in England and her colonies maintained about James II?", "question_choices": [ "that he would promote the spread of Protestantism", "that he would reduce the size of the British army and navy, leaving England and her colonies vulnerable to attack", "that he would advocate for Parliament’s independence from the monarchy", "that he would institute a Catholic absolute monarchy" ], "question_id": "fs-idm69581264", "question_text": "Which of the following represents a concern that those in England and her colonies maintained about James II?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 1, "ans_text": "B" }, "bloom": null, "hl_context": "<hl> In 1686 , James II applied his concept of a centralized state to the colonies by creating an enormous colony called the Dominion of New England . <hl> The Dominion included all the New England colonies ( Massachusetts , New Hampshire , Plymouth , Connecticut , New Haven , and Rhode Island ) and in 1688 was enlarged by the addition of New York and New Jersey . James placed in charge Sir Edmund Andros , a former colonial governor of New York . Loyal to James II and his family , Andros had little sympathy for New Englanders . His regime caused great uneasiness among New England Puritans when it called into question the many land titles that did not acknowledge the king and imposed fees for their reconfirmation . Andros also committed himself to enforcing the Navigation Acts , a move that threatened to disrupt the region ’ s trade , which was based largely on smuggling .", "hl_sentences": "In 1686 , James II applied his concept of a centralized state to the colonies by creating an enormous colony called the Dominion of New England .", "question": { "cloze_format": "___ was the Dominion of New England.", "normal_format": "What was the Dominion of New England?", "question_choices": [ "James II’s overthrow of the New England colonial governments", "the consolidated New England colony James II created", "Governor Edmund Andros’s colonial government in New York", "the excise taxes New England colonists had to pay to James II" ], "question_id": "fs-idm59484912", "question_text": "What was the Dominion of New England?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 1, "ans_text": "B" }, "bloom": null, "hl_context": "<hl> In the wake of the Stono Rebellion , South Carolina passed a new slave code in 1740 called An Act for the Better Ordering and Governing of Negroes and Other Slaves in the Province , also known as the Negro Act of 1740 . <hl> This law imposed new limits on enslaved people ’ s behavior , prohibiting them from assembling , growing their own food , learning to write , and traveling freely .", "hl_sentences": "In the wake of the Stono Rebellion , South Carolina passed a new slave code in 1740 called An Act for the Better Ordering and Governing of Negroes and Other Slaves in the Province , also known as the Negro Act of 1740 .", "question": { "cloze_format": "The Negro Act of 1740 was a reaction to ________.", "normal_format": "The Negro Act of 1740 was a reaction to what?", "question_choices": [ "fears of a slave conspiracy in the setting of thirteen fires in New York City", "the Stono Rebellion", "the Royal African Company’s monopoly", "the growing power of maroon communities" ], "question_id": "fs-idm16595280", "question_text": "The Negro Act of 1740 was a reaction to ________." }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 2, "ans_text": "Enslaved people conspiring to burn down the city and take control" }, "bloom": null, "hl_context": "That year , thirteen fires broke out in the city , one of which reduced the colony ’ s Fort George to ashes . <hl> Ever fearful of an uprising among enslaved New Yorkers , the city ’ s White residents spread rumors that the fires were part of a massive revolt in which enslaved people would murder White people , burn the city , and take over the colony . <hl> The Stono Rebellion was only a few years in the past , and throughout British America , fears of similar incidents were still fresh . Searching for solutions , and convinced their captives were the principal danger , nervous British authorities interrogated almost two hundred enslaved people and accused them of conspiracy . Rumors that Roman Catholics had joined the suspected conspiracy and planned to murder Protestant inhabitants of the city only added to the general hysteria . Very quickly , two hundred people were arrested , including a large number of the city ’ s enslaved population .", "hl_sentences": "Ever fearful of an uprising among enslaved New Yorkers , the city ’ s White residents spread rumors that the fires were part of a massive revolt in which enslaved people would murder White people , burn the city , and take over the colony .", "question": { "cloze_format": "The \"conspiracy\" of the New York Conspiracy Trials of 1741 was that ___.", "normal_format": "What was the “conspiracy” of the New York Conspiracy Trials of 1741?", "question_choices": [ "American patriots conspiring to overthrow the royal government", "indentured servants conspiring to overthrow their masters", "Enslaved people conspiring to burn down the city and take control", "Protestants conspiring to murder Catholics" ], "question_id": "fs-idp2581680", "question_text": "What was the “conspiracy” of the New York Conspiracy Trials of 1741?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 1, "ans_text": "B" }, "bloom": null, "hl_context": "<hl> During the eighteenth century , the British Atlantic experienced an outburst of Protestant revivalism known as the First Great Awakening . <hl> ( A Second Great Awakening would take place in the 1800s . ) During the First Great Awakening , evangelists came from the ranks of several Protestant denominations : Congregationalists , Anglicans ( members of the Church of England ) , and Presbyterians . They rejected what appeared to be sterile , formal modes of worship in favor of a vigorous emotional religiosity . <hl> Whereas Martin Luther and John Calvin had preached a doctrine of predestination and close reading of scripture , new evangelical ministers spread a message of personal and experiential faith that rose above mere book learning . <hl> Individuals could bring about their own salvation by accepting Christ , an especially welcome message for those who had felt excluded by traditional Protestantism : women , the young , and people at the lower end of the social spectrum .", "hl_sentences": "During the eighteenth century , the British Atlantic experienced an outburst of Protestant revivalism known as the First Great Awakening . Whereas Martin Luther and John Calvin had preached a doctrine of predestination and close reading of scripture , new evangelical ministers spread a message of personal and experiential faith that rose above mere book learning .", "question": { "cloze_format": "The First Great Awakening was ___.", "normal_format": "What was the First Great Awakening?", "question_choices": [ "a cultural and intellectual movement that emphasized reason and science over superstition and religion", "a Protestant revival that emphasized emotional, experiential faith over book learning", "a cultural shift that promoted Christianity among enslaved communities", "the birth of an American identity, promoted by Benjamin Franklin" ], "question_id": "fs-idm22490416", "question_text": "What was the First Great Awakening?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 0, "ans_text": "atheism" }, "bloom": null, "hl_context": "<hl> Several ideas dominated Enlightenment thought , including rationalism , empiricism , progressivism , and cosmopolitanism . <hl> Rationalism is the idea that humans are capable of using their faculty of reason to gain knowledge . This was a sharp turn away from the prevailing idea that people needed to rely on scripture or church authorities for knowledge . Empiricism promotes the idea that knowledge comes from experience and observation of the world . Progressivism is the belief that through their powers of reason and observation , humans could make unlimited , linear progress over time ; this belief was especially important as a response to the carnage and upheaval of the English Civil Wars in the seventeenth century . Finally , cosmopolitanism reflected Enlightenment thinkers ’ view of themselves as citizens of the world and actively engaged in it , as opposed to being provincial and close-minded . In all , Enlightenment thinkers endeavored to be ruled by reason , not prejudice .", "hl_sentences": "Several ideas dominated Enlightenment thought , including rationalism , empiricism , progressivism , and cosmopolitanism .", "question": { "cloze_format": "___ is not a tenet of Enlightenment.", "normal_format": "Which of the following is not a tenet of the Enlightenment?", "question_choices": [ "atheism", "empiricism", "progressivism", "rationalism" ], "question_id": "fs-idm42602160", "question_text": "Which of the following is not a tenet of the Enlightenment?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 2, "ans_text": "greater power in Europe and the world" }, "bloom": null, "hl_context": "<hl> Wars for empire composed a final link connecting the Atlantic sides of the British Empire . <hl> <hl> Great Britain fought four separate wars against Catholic France from the late 1600s to the mid - 1700s . <hl> Another war , the War of Jenkins ’ Ear , pitted Britain against Spain . These conflicts for control of North America also helped colonists forge important alliances with native peoples , as different tribes aligned themselves with different European powers .", "hl_sentences": "Wars for empire composed a final link connecting the Atlantic sides of the British Empire . Great Britain fought four separate wars against Catholic France from the late 1600s to the mid - 1700s .", "question": { "cloze_format": "The primary goal of Britain's war for empire from 1688 to 1763 was ___.", "normal_format": "What was the primary goal of Britain’s wars for empire from 1688 to 1763?", "question_choices": [ "control of North America", "control of Native Americans", "greater power in Europe and the world", "defeat of Catholicism" ], "question_id": "fs-idm35145952", "question_text": "What was the primary goal of Britain’s wars for empire from 1688 to 1763?" }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 3, "ans_text": "D" }, "bloom": null, "hl_context": "<hl> The British fared poorly in the first years of the war . <hl> <hl> In 1754 , the French and their native allies forced Washington to surrender at Fort Necessity , a hastily built fort constructed after his attack on the French . <hl> In 1755 , Britain dispatched General Edward Braddock to the colonies to take Fort Duquesne . The French , aided by the Potawotomis , Ottawas , Shawnees , and Delawares , ambushed the fifteen hundred British soldiers and Virginia militia who marched to the fort . The attack sent panic through the British force , and hundreds of British soldiers and militiamen died , including General Braddock . The campaign of 1755 proved to be a disaster for the British . In fact , the only British victory that year was the capture of Nova Scotia . In 1756 and 1757 , Britain suffered further defeats with the fall of Fort Oswego and Fort William Henry ( Figure 4.18 ) . <hl> The final imperial war , the French and Indian War ( 1754 – 1763 ) , known as the Seven Years ’ War ( 1756 – 1763 ) in Europe , proved to be the decisive contest between Britain and France in America . <hl> It began over rival claims along the frontier in present-day western Pennsylvania . Well-connected planters from Virginia faced stagnant tobacco prices and hoped expanding into these western lands would stabilize their wealth and status . Some of them established the Ohio Company of Virginia in 1748 , and the British crown granted the company half a million acres in 1749 . However , the French also claimed the lands of the Ohio Company , and to protect the region they established Fort Duquesne in 1754 , where the Ohio , Monongahela , and Allegheny Rivers met . The war began in May 1754 because of these competing claims between Britain and France . Twenty-two-year-old Virginian George Washington , a surveyor whose family helped to found the Ohio Company , gave the command to fire on French soldiers near present-day Uniontown , Pennsylvania . This incident on the Pennsylvania frontier proved to be a decisive event that led to imperial war . For the next decade , fighting took place along the frontier of New France and British America from Virginia to Maine . The war also spread to Europe as France and Britain looked to gain supremacy in the Atlantic World .", "hl_sentences": "The British fared poorly in the first years of the war . In 1754 , the French and their native allies forced Washington to surrender at Fort Necessity , a hastily built fort constructed after his attack on the French . The final imperial war , the French and Indian War ( 1754 – 1763 ) , known as the Seven Years ’ War ( 1756 – 1763 ) in Europe , proved to be the decisive contest between Britain and France in America .", "question": { "cloze_format": "The main combatants in the French and Indian war were ___.", "normal_format": "Who were the main combatants in the French and Indian War?", "question_choices": [ "France against Native Americans", "Great Britain against Native Americans", "Great Britain against France", "Great Britain against the French and their Native American allies" ], "question_id": "fs-idm34276800", "question_text": "Who were the main combatants in the French and Indian War?" }, "references_are_paraphrase": null } ]
4
4.1 Charles II and the Restoration Colonies Learning Objectives By the end of this section, you will be able to: Analyze the causes and consequences of the Restoration Identify the Restoration colonies and their role in the expansion of the Empire When Charles II ascended the throne in 1660, English subjects on both sides of the Atlantic celebrated the restoration of the English monarchy after a decade of living without a king as a result of the English Civil Wars. Charles II lost little time in strengthening England’s global power. From the 1660s to the 1680s, Charles II added more possessions to England’s North American holdings by establishing the Restoration colonies of New York and New Jersey (taking these areas from the Dutch) as well as Pennsylvania and the Carolinas. In order to reap the greatest economic benefit from England’s overseas possessions, Charles II enacted the mercantilist Navigation Acts, although many colonial merchants ignored them because enforcement remained lax. CHARLES II The chronicle of Charles II begins with his father, Charles I. Charles I ascended the English throne in 1625 and soon married a French Catholic princess, Henrietta Maria, who was not well liked by English Protestants because she openly practiced Catholicism during her husband’s reign. The most outspoken Protestants, the Puritans, had a strong voice in Parliament in the 1620s, and they strongly opposed the king’s marriage and his ties to Catholicism. When Parliament tried to contest his edicts, including the king’s efforts to impose taxes without Parliament’s consent, Charles I suspended Parliament in 1629 and ruled without one for the next eleven years. The ensuing struggle between the king and Parliament led to the outbreak of war. The English Civil War lasted from 1642 to 1649 and pitted the king and his Royalist supporters against Oliver Cromwell and his Parliamentary forces. After years of fighting, the Parliamentary forces gained the upper hand, and in 1649, they charged Charles I with treason and beheaded him. The monarchy was dissolved, and England became a republic: a state without a king. Oliver Cromwell headed the new English Commonwealth, and the period known as the English interregnum , or the time between kings, began. Though Cromwell enjoyed widespread popularity at first, over time he appeared to many in England to be taking on the powers of a military dictator. Dissatisfaction with Cromwell grew. When he died in 1658 and control passed to his son Richard, who lacked the political skills of his father, a majority of the English people feared an alternate hereditary monarchy in the making. They had had enough and asked Charles II to be king. In 1660, they welcomed the son of the executed king Charles I back to the throne to resume the English monarchy and bring the interregnum to an end ( Figure 4.3 ). The return of Charles II is known as the Restoration. Charles II was committed to expanding England’s overseas possessions. His policies in the 1660s through the 1680s established and supported the Restoration colonies : the Carolinas, New Jersey, New York, and Pennsylvania. All the Restoration colonies started as proprietary colonies , that is, the king gave each colony to a trusted individual, family, or group. THE CAROLINAS Charles II hoped to establish English control of the area between Virginia and Spanish Florida. To that end, he issued a royal charter in 1663 to eight trusted and loyal supporters, each of whom was to be a feudal-style proprietor of a region of the province of Carolina. These proprietors did not relocate to the colonies, however. Instead, English plantation owners from the tiny Caribbean island of Barbados, already a well-established English sugar colony fueled by slave labor, migrated to the southern part of Carolina to settle there. In 1670, they established Charles Town (later Charleston), named in honor of Charles II, at the junction of the Ashley and Cooper Rivers ( Figure 4.4 ). As the settlement around Charles Town grew, it began to produce livestock for export to the West Indies. In the northern part of Carolina, settlers used sap from pine trees to create tar and pitch used to waterproof wooden ships. Political disagreements between settlers in the northern and southern parts of Carolina escalated in the 1710s through the 1720s and led to the creation, in 1729, of two colonies, North and South Carolina. The southern part of Carolina had been producing rice and indigo (a plant that yields a dark blue dye used by English royalty) since the 1700s, and South Carolina continued to depend on these main crops. North Carolina continued to produce items for ships, especially turpentine and tar, and its population increased as Virginians moved there to expand their tobacco holdings. Tobacco was the primary export of both Virginia and North Carolina, which also traded in deerskins and captured people from Africa. Slavery developed quickly in the Carolinas, largely because so many of the early migrants came from Barbados, where slavery was well established. By the end of the 1600s, a very wealthy class of rice planters, who relied on enslaved people for labor, had attained dominance in the southern part of the Carolinas, especially around Charles Town. By 1715, South Carolina had a Black majority because of the number of enslaved people in the colony. The legal basis for slavery was established in the early 1700s as the Carolinas began to pass slave laws based on the Barbados slave codes of the late 1600s. These laws reduced Africans to the status of property to be bought and sold as other commodities. As in other areas of English settlement, native peoples in the Carolinas suffered tremendously from the introduction of European diseases. Despite the effects of disease, Native Americans in the area endured and, following the pattern elsewhere in the colonies, grew dependent on European goods. Local Yamasee and Creek tribes built up a trade deficit with the English, trading deerskins and captive people for European guns. English settlers exacerbated tensions with local Native American tribes, especially the Yamasee, by expanding their rice and tobacco fields into Native American lands. Worse still, English traders took Native women captive as payment for debts. The outrages committed by traders, combined with the seemingly unstoppable expansion of English settlement onto native land, led to the outbreak of the Yamasee War (1715–1718), an effort by a coalition of local tribes to drive away the European invaders. This native effort to force the newcomers back across the Atlantic nearly succeeded in annihilating the Carolina colonies. Only when the Cherokee allied themselves with the English did the coalition’s goal of eliminating the English from the region falter. The Yamasee War demonstrates the key role native peoples played in shaping the outcome of colonial struggles and, perhaps most important, the disunity that existed between different native groups. NEW YORK AND NEW JERSEY Charles II also set his sights on the Dutch colony of New Netherland. The English takeover of New Netherland originated in the imperial rivalry between the Dutch and the English. During the Anglo-Dutch wars of the 1650s and 1660s, the two powers attempted to gain commercial advantages in the Atlantic World. During the Second Anglo-Dutch War (1664–1667), English forces gained control of the Dutch fur trading colony of New Netherland, and in 1664, Charles II gave this colony (including present-day New Jersey) to his brother James, Duke of York (later James II). The colony and city were renamed New York in his honor. The Dutch in New York chafed under English rule. In 1673, during the Third Anglo-Dutch War (1672–1674), the Dutch recaptured the colony. However, at the end of the conflict, the English had regained control ( Figure 4.5 ). The Duke of York had no desire to govern locally or listen to the wishes of local colonists. It wasn’t until 1683, therefore, almost 20 years after the English took control of the colony, that colonists were able to convene a local representative legislature. The assembly’s 1683 Charter of Liberties and Privileges set out the traditional rights of Englishmen, like the right to trial by jury and the right to representative government. The English continued the Dutch patroonship system, granting large estates to a favored few families. The largest of these estates, at 160,000 acres, was given to Robert Livingston in 1686. The Livingstons and the other manorial families who controlled the Hudson River Valley formed a formidable political and economic force. Eighteenth-century New York City, meanwhile, contained a variety of people and religions—as well as Dutch and English people, it held French Protestants (Huguenots), Jews, Puritans, Quakers, Anglicans, and a large population of enslaved people. As they did in other zones of colonization, native peoples played a key role in shaping the history of colonial New York. After decades of war in the 1600s, the powerful Five Nations of the Iroquois, composed of the Mohawk, Oneida, Onondaga, Cayuga, and Seneca, successfully pursued a policy of neutrality with both the English and, to the north, the French in Canada during the first half of the 1700s. This native policy meant that the Iroquois continued to live in their own villages under their own government while enjoying the benefits of trade with both the French and the English. PENNSYLVANIA The Restoration colonies also included Pennsylvania, which became the geographic center of British colonial America. Pennsylvania (which means “Penn’s Woods” in Latin) was created in 1681, when Charles II bestowed the largest proprietary colony in the Americas on William Penn ( Figure 4.6 ) to settle the large debt he owed the Penn family. William Penn’s father, Admiral William Penn, had served the English crown by helping take Jamaica from the Spanish in 1655. The king personally owed the Admiral money as well. Like early settlers of the New England colonies, Pennsylvania’s first colonists migrated mostly for religious reasons. William Penn himself was a Quaker, a member of a new Protestant denomination called the Society of Friends. George Fox had founded the Society of Friends in England in the late 1640s, having grown dissatisfied with Puritanism and the idea of predestination. Rather, Fox and his followers stressed that everyone had an “inner light” inside him or her, a spark of divinity. They gained the name Quakers because they were said to quake when the inner light moved them. Quakers rejected the idea of worldly rank, believing instead in a new and radical form of social equality. Their speech reflected this belief in that they addressed all others as equals, using “thee” and “thou” rather than terms like “your lordship” or “my lady” that were customary for privileged individuals of the hereditary elite. The English crown persecuted Quakers in England, and colonial governments were equally harsh; Massachusetts even executed several early Quakers who had gone to proselytize there. To avoid such persecution, Quakers and their families at first created a community on the sugar island of Barbados. Soon after its founding, however, Pennsylvania became the destination of choice. Quakers flocked to Pennsylvania as well as New Jersey, where they could preach and practice their religion in peace. Unlike New England, whose official religion was Puritanism, Pennsylvania did not establish an official church. Indeed, the colony allowed a degree of religious tolerance found nowhere else in English America. To help encourage immigration to his colony, Penn promised fifty acres of land to people who agreed to come to Pennsylvania and completed their term of service. Not surprisingly, those seeking a better life came in large numbers, so much so that Pennsylvania relied on indentured servants more than any other colony. One of the primary tenets of Quakerism is pacifism, which led William Penn to establish friendly relationships with local native peoples. He formed a covenant of friendship with the Lenni Lenape (Delaware) tribe, buying their land for a fair price instead of taking it by force. In 1701, he also signed a treaty with the Susquehannocks to avoid war. Unlike other colonies, Pennsylvania did not experience war on the frontier with native peoples during its early history. As an important port city, Philadelphia grew rapidly. Quaker merchants there established contacts throughout the Atlantic world and participated in the thriving African slave trade. Some Quakers, who were deeply troubled by the contradiction between their belief in the “inner light” and the practice of slavery, rejected the practice and engaged in efforts to abolish it altogether. Philadelphia also acted as a magnet for immigrants, who came not only from England, but from all over Europe by the hundreds of thousands. The city, and indeed all of Pennsylvania, appeared to be the best country for poor men and women, many of whom arrived as servants and dreamed of owning land. A very few, like the fortunate Benjamin Franklin, a runaway from Puritan Boston, did extraordinarily well. Other immigrant groups in the colony, most notably Germans and Scotch-Irish (families from Scotland and England who had first lived in Ireland before moving to British America), greatly improved their lot in Pennsylvania. Of course, Africans imported into the colony to labor for White masters fared far worse. Americana John Wilson Offers Reward for Escaped Prisoners The American Weekly Mercury , published by William Bradford, was Philadelphia’s first newspaper. This advertisement from “John Wilson, Goaler ” (jailer) offers a reward for anyone capturing several men who escaped from the jail. BROKE out of the Common Goal of Philadelphia, the 15th of this Instant February, 1721, the following Persons : John Palmer, also Plumly, alias Paine, Servant to Joseph Jones, run away and was lately taken up at New-York. He is fully described in the American Mercury, Novem. 23, 1721. He has a Cinnamon coloured Coat on, a middle sized fresh coloured Man. His Master will give a Pistole Reward to any who Shall Secure him, besides what is here offered. Daniel Oughtopay, A Dutchman, aged about 24 Years, Servant to Dr. Johnston in Amboy. He is a thin Spare man, grey Drugget Waistcoat and Breeches and a light-coloured Coat on. Ebenezor Mallary, a New-England, aged about 24 Years, is a middle-sized thin Man, having on a Snuff colour’d Coat, and ordinary Ticking Waistcoat and Breeches. He has dark brown strait Hair. Matthew Dulany, an Irish Man, down-look’d Swarthy Complexion, and has on an Olive-coloured Cloth Coat and Waistcoat with Cloth Buttons. John Flemming, an Irish Lad, aged about 18, belonging to Mr. Miranda, Merchant in this City. He has no Coat, a grey Drugget Waistcoat, and a narrow brim’d Hat on. John Corbet, a Shropshire Man, a Runaway Servant from Alexander Faulkner of Maryland, broke out on the 12th Instant. He has got a double-breasted Sailor’s Jacket on lined with red Bays, pretends to be a Sailor, and once taught School at Josephs Collings’s in the Jerseys. Whoever takes up and secures all, or any One of these Felons, shall have a Pistole Reward for each of them and reasonable Charges, paid them by John Wilson, Goaler —Advertisement from the American Weekly Mercury , 1722 What do the descriptions of the men tell you about life in colonial Philadelphia? THE NAVIGATION ACTS Creating wealth for the Empire remained a primary goal, and in the second half of the seventeenth century, especially during the Restoration, England attempted to gain better control of trade with the American colonies. The mercantilist policies by which it tried to achieve this control are known as the Navigation Acts . The 1651 Navigation Ordinance, a product of Cromwell’s England, required that only English ships carry goods between England and the colonies, and that the captain and three-fourths of the crew had to be English. The ordinance further listed “enumerated articles” that could be transported only to England or to English colonies, including the most lucrative commodities like sugar and tobacco as well as indigo, rice, molasses, and naval stores such as turpentine. All were valuable goods not produced in England and in demand by the British navy. After ascending the throne, Charles II approved the 1660 Navigation Act, which restated the 1651 act to ensure a monopoly on imports from the colonies. Other Navigation Acts included the 1663 Staple Act and the 1673 Plantation Duties Act. The Staple Act barred colonists from importing goods that had not been made in England, creating a profitable monopoly for English exporters and manufacturers. The Plantation Duties Act taxed enumerated articles exported from one colony to another, a measure aimed principally at New Englanders, who transported great quantities of molasses from the West Indies, including smuggled molasses from French-held islands, to make into rum. In 1675, Charles II organized the Lords of Trade and Plantation, commonly known as the Lords of Trade, an administrative body intended to create stronger ties between the colonial governments and the crown. However, the 1696 Navigation Act created the Board of Trade, replacing the Lords of Trade. This act, meant to strengthen enforcement of customs laws, also established vice-admiralty courts where the crown could prosecute customs violators without a jury. Under this act, customs officials were empowered with warrants known as “writs of assistance” to board and search vessels suspected of containing smuggled goods. Despite the Navigation Acts, however, Great Britain exercised lax control over the English colonies during most of the eighteenth century because of the policies of Prime Minister Robert Walpole. During his long term (1721–1742), Walpole governed according to his belief that commerce flourished best when it was not encumbered with restrictions. Historians have described this lack of strict enforcement of the Navigation Acts as salutary neglect . In addition, nothing prevented colonists from building their own fleet of ships to engage in trade. New England especially benefited from both salutary neglect and a vibrant maritime culture made possible by the scores of trading vessels built in the northern colonies. The case of the 1733 Molasses Act illustrates the weaknesses of British mercantilist policy. The 1733 act placed a sixpence-per-gallon duty on raw sugar, rum, and molasses from Britain’s competitors, the French and the Dutch, in order to give an advantage to British West Indian producers. Because the British did not enforce the 1733 law, however, New England mariners routinely smuggled these items from the French and Dutch West Indies more cheaply than they could buy them on English islands. 4.2 The Glorious Revolution and the English Empire Learning Objectives By the end of this section, you will be able to: Identify the causes of the Glorious Revolution Explain the outcomes of the Glorious Revolution During the brief rule of King James II, many in England feared the imposition of a Catholic absolute monarchy by the man who modeled his rule on that of his French Catholic cousin, Louis XIV. Opposition to James II, spearheaded by the English Whig party, overthrew the king in the Glorious Revolution of 1688–1689. This paved the way for the Protestant reign of William of Orange and his wife Mary (James’s Protestant daughter). JAMES II AND THE GLORIOUS REVOLUTION King James II ( Figure 4.7 ), the second son of Charles I, ascended the English throne in 1685 on the death of his brother, Charles II. James then worked to model his rule on the reign of the French Catholic King Louis XIV, his cousin. This meant centralizing English political strength around the throne, giving the monarchy absolute power. Also like Louis XIV, James II practiced a strict and intolerant form of Roman Catholicism after he converted from Protestantism in the late 1660s. He had a Catholic wife, and when they had a son, the potential for a Catholic heir to the English throne became a threat to English Protestants. James also worked to modernize the English army and navy. The fact that the king kept a standing army in times of peace greatly alarmed the English, who believed that such a force would be used to crush their liberty. As James’s strength grew, his opponents feared their king would turn England into a Catholic monarchy with absolute power over her people. In 1686, James II applied his concept of a centralized state to the colonies by creating an enormous colony called the Dominion of New England . The Dominion included all the New England colonies (Massachusetts, New Hampshire, Plymouth, Connecticut, New Haven, and Rhode Island) and in 1688 was enlarged by the addition of New York and New Jersey. James placed in charge Sir Edmund Andros, a former colonial governor of New York. Loyal to James II and his family, Andros had little sympathy for New Englanders. His regime caused great uneasiness among New England Puritans when it called into question the many land titles that did not acknowledge the king and imposed fees for their reconfirmation. Andros also committed himself to enforcing the Navigation Acts, a move that threatened to disrupt the region’s trade, which was based largely on smuggling. In England, opponents of James II’s efforts to create a centralized Catholic state were known as Whigs. The Whigs worked to depose James, and in late 1688 they succeeded, an event they celebrated as the Glorious Revolution while James fled to the court of Louis XIV in France. William III (William of Orange) and his wife Mary II ascended the throne in 1689. The Glorious Revolution spilled over into the colonies. In 1689, Bostonians overthrew the government of the Dominion of New England and jailed Sir Edmund Andros as well as other leaders of the regime ( Figure 4.8 ). The removal of Andros from power illustrates New England’s animosity toward the English overlord who had, during his tenure, established Church of England worship in Puritan Boston and vigorously enforced the Navigation Acts, to the chagrin of those in port towns. In New York, the same year that Andros fell from power, Jacob Leisler led a group of Protestant New Yorkers against the dominion government. Acting on his own authority, Leisler assumed the role of King William’s governor and organized intercolonial military action independent of British authority. Leisler’s actions usurped the crown’s prerogative and, as a result, he was tried for treason and executed. In 1691, England restored control over the Province of New York. The Glorious Revolution provided a shared experience for those who lived through the tumult of 1688 and 1689. Subsequent generations kept the memory of the Glorious Revolution alive as a heroic defense of English liberty against a would-be tyrant. ENGLISH LIBERTY The Glorious Revolution led to the establishment of an English nation that limited the power of the king and provided protections for English subjects. In October 1689, the same year that William and Mary took the throne, the 1689 Bill of Rights established a constitutional monarchy. It stipulated Parliament’s independence from the monarchy and protected certain of Parliament’s rights, such as the right to freedom of speech, the right to regular elections, and the right to petition the king. The 1689 Bill of Rights also guaranteed certain rights to all English subjects, including trial by jury and habeas corpus (the requirement that authorities bring an imprisoned person before a court to demonstrate the cause of the imprisonment). John Locke (1632–1704), a doctor and educator who had lived in exile in Holland during the reign of James II and returned to England after the Glorious Revolution, published his Two Treatises of Government in 1690. In it, he argued that government was a form of contract between the leaders and the people, and that representative government existed to protect “life, liberty and property.” Locke rejected the divine right of kings and instead advocated for the central role of Parliament with a limited monarchy. Locke’s political philosophy had an enormous impact on future generations of colonists and established the paramount importance of representation in government. The Glorious Revolution also led to the English Toleration Act of 1689, a law passed by Parliament that allowed for greater religious diversity in the Empire. This act granted religious tolerance to nonconformist Trinitarian Protestants (those who believed in the Holy Trinity of God the Father, Son, and Holy Ghost), such as Baptists (those who advocated adult baptism) and Congregationalists (those who followed the Puritans’ lead in creating independent churches). While the Church of England remained the official state religious establishment, the Toleration Act gave much greater religious freedom to nonconformists. However, this tolerance did not extend to Catholics, who were routinely excluded from political power. The 1689 Toleration Act extended to the British colonies, where several colonies—Pennsylvania, Rhode Island, Delaware, and New Jersey—refused to allow the creation of an established colonial church, a major step toward greater religious diversity. 4.3 An Empire of Slavery and the Consumer Revolution Learning Objectives By the end of this section, you will be able to: Analyze the role slavery played in the history and economy of the British Empire Explain the effects of the 1739 Stono Rebellion and the 1741 New York Conspiracy Trials Describe the consumer revolution and its effect on the life of the colonial gentry and other settlers Slavery formed a cornerstone of the British Empire in the eighteenth century. Every colony had enslaved people, from the southern rice plantations in Charles Town, South Carolina, to the northern wharves of Boston. Slavery was more than a labor system; it also influenced every aspect of colonial thought and culture. The uneven relationship it engendered gave White colonists an exaggerated sense of their own status. English liberty gained greater meaning and coherence for White people when they contrasted their status to that of the unfree class of enslaved Black people in British America. African slavery provided White colonists with a shared racial bond and identity. SLAVERY AND THE STONO REBELLION The transport of captured Africans to the American colonies accelerated in the second half of the seventeenth century. In 1660, Charles II created the Royal African Company ( Figure 4.9 ) to trade in African goods and enslaved people.. His brother, James II, led the company before ascending the throne. Under both these kings, the Royal African Company had a monopoly on the slave trade to the English colonies. Between 1672 and 1713, the company bought 125,000 captives on the African coast, losing 20 percent of them to death on the Middle Passage, the journey from the African coast to the Americas. The Royal African Company’s monopoly ended in 1689 as a result of the Glorious Revolution. After that date, many more English merchants engaged in the slave trade, greatly increasing the number of captives being transported. Africans who survived the brutal Middle Passage usually arrived in the West Indies, often in Barbados. From there, they were transported to the mainland English colonies on company ships. While merchants in London, Bristol, and Liverpool lined their pockets, Africans trafficked by the company endured a nightmare of misery, privation, and dislocation. Enslaved Africans strove to adapt to their new lives by forming new communities among themselves, often adhering to traditional African customs and healing techniques. Indeed, the development of families and communities formed the most important response to the trauma of being enslaved. Others dealt with the trauma of their situation by actively resisting their condition, whether by defying their captors or running away. Escaped enslaved people formed what were called “maroon” communities, groups that successfully resisted recapture and formed their own autonomous groups. The most prominent of these communities lived in the interior of Jamaica, controlling the area and keeping the British away. Enslaved people everywhere resisted their exploitation and attempted to gain freedom. They fully understood that rebellions would bring about massive retaliation from White people and therefore had little chance of success. Even so, rebellions occurred frequently. One notable uprising that became known as the Stono Rebellion took place in South Carolina in September 1739. A literate Angolan named Jemmy led a large group of captive Africans in an armed insurrection against White colonists. The militia suppressed the rebellion after a battle in which both enslaved people and militiamen were killed, and the remaining rebels were executed or sold to enslavers in the West Indies. Jemmy is believed to have been taken from the Kingdom of Kongo, an area where the Portuguese had introduced Catholicism. Other enslaved people in South Carolina may have had a similar background: Africa-born and familiar with White people. If so, this common background may have made it easier for Jemmy to communicate with the other rebels, enabling them to work together to resist their enslavement even though enslavers labored to keep their captives from forging such communities. In the wake of the Stono Rebellion, South Carolina passed a new slave code in 1740 called An Act for the Better Ordering and Governing of Negroes and Other Slaves in the Province, also known as the Negro Act of 1740. This law imposed new limits on enslaved people’s behavior, prohibiting them from assembling, growing their own food, learning to write, and traveling freely. THE NEW YORK CONSPIRACY TRIALS OF 1741 Eighteenth-century New York City contained many different ethnic groups, and conflicts among them created strain. In addition, one in five New Yorkers was an enslaved person, and tensions ran high between the enslaved and the free population, especially in the aftermath of the Stono Rebellion. These tensions burst forth in 1741. That year, thirteen fires broke out in the city, one of which reduced the colony’s Fort George to ashes. Ever fearful of an uprising among enslaved New Yorkers, the city’s White residents spread rumors that the fires were part of a massive revolt in which enslaved people would murder White people, burn the city, and take over the colony. The Stono Rebellion was only a few years in the past, and throughout British America, fears of similar incidents were still fresh. Searching for solutions, and convinced their captives were the principal danger, nervous British authorities interrogated almost two hundred enslaved people and accused them of conspiracy. Rumors that Roman Catholics had joined the suspected conspiracy and planned to murder Protestant inhabitants of the city only added to the general hysteria. Very quickly, two hundred people were arrested, including a large number of the city’s enslaved population. After a quick series of trials at City Hall, known as the New York Conspiracy Trials of 1741, the government executed seventeen New Yorkers. Thirteen Black men were publicly burned at the stake, while the others (including four Whites) were hanged ( Figure 4.10 ). Seventy people were sold to the West Indies. Little evidence exists to prove that an elaborate conspiracy, like the one White New Yorkers imagined, actually existed. The events of 1741 in New York City illustrate the racial divide in British America, where panic among Whites spurred great violence against and repression of the feared enslaved population. In the end, the Conspiracy Trials furthered White dominance and power over enslaved New Yorkers. COLONIAL GENTRY AND THE CONSUMER REVOLUTION British Americans’ reliance on indentured servitude and slavery to meet the demand for colonial labor helped give rise to a wealthy colonial class—the gentry—in the Chesapeake tobacco colonies and elsewhere. To be “genteel,” that is, a member of the gentry, meant to be refined, free of all rudeness. The British American gentry modeled themselves on the English aristocracy, who embodied the ideal of refinement and gentility. They built elaborate mansions to advertise their status and power. William Byrd II of Westover, Virginia, exemplifies the colonial gentry; a wealthy planter and slaveholder, he is known for founding Richmond and for his diaries documenting the life of a gentleman planter ( Figure 4.11 ). My Story William Byrd’s Secret Diary The diary of William Byrd, a Virginia planter, provides a unique way to better understand colonial life on a plantation ( Figure 4.12 ). What does it show about daily life for a "gentleman" planter and enslaver? What does it show about slavery? August 27, 1709 I rose at 5 o’clock and read two chapters in Hebrew and some Greek in Josephus. I said my prayers and ate milk for breakfast. I danced my dance. I had like to have whipped my maid Anaka for her laziness but I forgave her. I read a little geometry. I denied my man G-r-l to go to a horse race because there was nothing but swearing and drinking there. I ate roast mutton for dinner. In the afternoon I played at piquet with my own wife and made her out of humor by cheating her. I read some Greek in Homer. Then I walked about the plantation. I lent John H-ch £7 [7 English pounds] in his distress. I said my prayers and had good health, good thoughts, and good humor, thanks be to God Almighty. September 6, 1709 About one o’clock this morning my wife was happily delivered of a son, thanks be to God Almighty. I was awake in a blink and rose and my cousin Harrison met me on the stairs and told me it was a boy. We drank some French wine and went to bed again and rose at 7 o’clock. I read a chapter in Hebrew and then drank chocolate with the women for breakfast. I returned God humble thanks for so great a blessing and recommended my young son to His divine protection. . . . September 15, 1710 I rose at 5 o’clock and read two chapters in Hebrew and some Greek in Thucydides. I said my prayers and ate milk and pears for breakfast. About 7 o’clock the negro boy [ or Betty] that ran away was brought home. My wife against my will caused little Jenny to be burned with a hot iron, for which I quarreled with her. . . . One of the ways in which the gentry set themselves apart from others was through their purchase, consumption, and display of goods. An increased supply of consumer goods from England that became available in the eighteenth century led to a phenomenon called the consumer revolution. These products linked the colonies to Great Britain in real and tangible ways. Indeed, along with the colonial gentry, ordinary settlers in the colonies also participated in the frenzy of consumer spending on goods from Great Britain. Tea, for example, came to be regarded as the drink of the Empire, with or without fashionable tea sets. The consumer revolution also made printed materials more widely available. Before 1680, for instance, no newspapers had been printed in colonial America. In the eighteenth century, however, a flood of journals, books, pamphlets, and other publications became available to readers on both sides of the Atlantic. This shared trove of printed matter linked members of the Empire by creating a community of shared tastes and ideas. Cato’s Letters , by Englishmen John Trenchard and Thomas Gordon, was one popular series of 144 pamphlets. These Whig circulars were published between 1720 and 1723 and emphasized the glory of England, especially its commitment to liberty. However, the pamphlets cautioned readers to be ever vigilant and on the lookout for attacks upon that liberty. Indeed, Cato’s Letters suggested that there were constant efforts to undermine and destroy it. Another very popular publication was the English gentlemen’s magazine the Spectator , published between 1711 and 1714. In each issue, “Mr. Spectator” observed and commented on the world around him. What made the Spectator so wildly popular was its style; the essays were meant to persuade, and to cultivate among readers a refined set of behaviors, rejecting deceit and intolerance and focusing instead on the polishing of genteel taste and manners. Novels, a new type of literature, made their first appearance in the eighteenth century and proved very popular in the British Atlantic. Daniel Defoe’s Robinson Crusoe and Samuel Richardson’s Pamela: Or, Virtue Rewarded found large and receptive audiences. Reading also allowed female readers the opportunity to interpret what they read without depending on a male authority to tell them what to think. Few women beyond the colonial gentry, however, had access to novels. 4.4 Great Awakening and Enlightenment Learning Objectives By the end of this section, you will be able to: Explain the significance of the Great Awakening Describe the genesis, central ideas, and effects of the Enlightenment in British North America Two major cultural movements further strengthened Anglo-American colonists’ connection to Great Britain: the Great Awakening and the Enlightenment. Both movements began in Europe, but they advocated very different ideas: the Great Awakening promoted a fervent, emotional religiosity, while the Enlightenment encouraged the pursuit of reason in all things. On both sides of the Atlantic, British subjects grappled with these new ideas. THE FIRST GREAT AWAKENING During the eighteenth century, the British Atlantic experienced an outburst of Protestant revivalism known as the First Great Awakening . (A Second Great Awakening would take place in the 1800s.) During the First Great Awakening, evangelists came from the ranks of several Protestant denominations: Congregationalists, Anglicans (members of the Church of England), and Presbyterians. They rejected what appeared to be sterile, formal modes of worship in favor of a vigorous emotional religiosity. Whereas Martin Luther and John Calvin had preached a doctrine of predestination and close reading of scripture, new evangelical ministers spread a message of personal and experiential faith that rose above mere book learning. Individuals could bring about their own salvation by accepting Christ, an especially welcome message for those who had felt excluded by traditional Protestantism: women, the young, and people at the lower end of the social spectrum. The Great Awakening caused a split between those who followed the evangelical message (the “New Lights”) and those who rejected it (the “Old Lights”). The elite ministers in British America were firmly Old Lights, and they censured the new revivalism as chaos. Indeed, the revivals did sometimes lead to excess. In one notorious incident in 1743, an influential New Light minister named James Davenport urged his listeners to burn books. The next day, he told them to burn their clothes as a sign of their casting off the sinful trappings of the world. He then took off his own pants and threw them into the fire, but a woman saved them and tossed them back to Davenport, telling him he had gone too far. Another outburst of Protestant revivalism began in New Jersey, led by a minister of the Dutch Reformed Church named Theodorus Frelinghuysen. Frelinghuysen’s example inspired other ministers, including Gilbert Tennent, a Presbyterian. Tennant helped to spark a Presbyterian revival in the Middle Colonies (Pennsylvania, New York, and New Jersey), in part by founding a seminary to train other evangelical clergyman. New Lights also founded colleges in Rhode Island and New Hampshire that would later become Brown University and Dartmouth College. In Northampton, Massachusetts, Jonathan Edwards led still another explosion of evangelical fervor. Edwards had grown frustrated with lack of religious emotion among practicing Christians within his community. He wanted to enliven religious practice. An important component of his approach involved using vivid depictions of the terrors of hell ( Figure 4.13 ). Edward's best-known sermon, “Sinners in the Hands of an Angry God,” perfectly exemplifies this terrifying approach. One passage reads: “The wrath of God burns against them [sinners], their damnation don’t slumber, the pit is prepared, the fire is made ready, the furnace is now hot, ready to receive them, the flames do now rage and glow. The glittering sword is whet, and held over them, and the pit hath opened her mouth under them.” Edwards’s revival spread along the Connecticut River Valley, and news of the event spread rapidly through the frequent reprinting of his famous sermon. The foremost evangelical of the Great Awakening was an Anglican minister named George Whitefield. Like many evangelical ministers, Whitefield was itinerant, traveling the countryside instead of having his own church and congregation. Between 1739 and 1740, he electrified colonial listeners with his brilliant oratory. Americana Two Opposing Views of George Whitefield Not everyone embraced George Whitefield and other New Lights. Many established Old Lights decried the way the new evangelical religions appealed to people’s passions, rather than to traditional religious values. The two illustrations below present two very different visions of George Whitefield ( Figure 4.14 ). Compare the two images above. On the left is an illustration for Whitefield’s memoirs, while on the right is a cartoon satirizing the circus-like atmosphere that his preaching seemed to attract (Dr. Squintum was a nickname for Whitefield, who was cross-eyed). How do these two artists portray the same man? What emotions are the illustration for his memoirs intended to evoke? What details can you find in the cartoon that indicate the artist’s distaste for the preacher? The Great Awakening saw the rise of several Protestant denominations, including Methodists, Presbyterians, and Baptists (who emphasized adult baptism of converted Christians rather than infant baptism). These new churches gained converts and competed with older Protestant groups like Anglicans (members of the Church of England), Congregationalists (the heirs of Puritanism in America), and Quakers. The influence of these older Protestant groups, such as the New England Congregationalists, declined because of the Great Awakening. Nonetheless, the Great Awakening touched the lives of thousands on both sides of the Atlantic and provided a shared experience in the eighteenth-century British Empire. THE ENLIGHTENMENT The Enlightenment , or the Age of Reason, was an intellectual and cultural movement in the eighteenth century that emphasized reason over superstition and science over blind faith. Using the power of the press, Enlightenment thinkers like John Locke, Isaac Newton, and Voltaire questioned accepted knowledge and spread new ideas about openness, investigation, and religious tolerance throughout Europe and the Americas. Many consider the Enlightenment a major turning point in Western civilization, an age of light replacing an age of darkness. Several ideas dominated Enlightenment thought, including rationalism, empiricism, progressivism, and cosmopolitanism. Rationalism is the idea that humans are capable of using their faculty of reason to gain knowledge. This was a sharp turn away from the prevailing idea that people needed to rely on scripture or church authorities for knowledge. Empiricism promotes the idea that knowledge comes from experience and observation of the world. Progressivism is the belief that through their powers of reason and observation, humans could make unlimited, linear progress over time; this belief was especially important as a response to the carnage and upheaval of the English Civil Wars in the seventeenth century. Finally, cosmopolitanism reflected Enlightenment thinkers’ view of themselves as citizens of the world and actively engaged in it, as opposed to being provincial and close-minded. In all, Enlightenment thinkers endeavored to be ruled by reason, not prejudice. The Freemasons were a fraternal society that advocated Enlightenment principles of inquiry and tolerance. Freemasonry originated in London coffeehouses in the early eighteenth century, and Masonic lodges (local units) soon spread throughout Europe and the British colonies. One prominent Freemason, Benjamin Franklin, stands as the embodiment of the Enlightenment in British America ( Figure 4.15 ). Born in Boston in 1706 to a large Puritan family, Franklin loved to read, although he found little beyond religious publications in his father’s house. In 1718 he was apprenticed to his brother to work in a print shop, where he learned how to be a good writer by copying the style he found in the Spectator , which his brother printed. At the age of seventeen, the independent-minded Franklin ran away, eventually ending up in Quaker Philadelphia. There he began publishing the Pennsylvania Gazette in the late 1720s, and in 1732 he started his annual publication Poor Richard: An Almanack , in which he gave readers much practical advice, such as “Early to bed, early to rise, makes a man healthy, wealthy, and wise.” Franklin subscribed to deism , an Enlightenment-era belief in a God who created, but has no continuing involvement in, the world and the events within it. Deists also advanced the belief that personal morality—an individual’s moral compass, leading to good works and actions—is more important than strict church doctrines. Franklin’s deism guided his many philanthropic projects. In 1731, he established a reading library that became the Library Company of Philadelphia. In 1743, he founded the American Philosophical Society to encourage the spirit of inquiry. In 1749, he provided the foundation for the University of Pennsylvania, and in 1751, he helped found Pennsylvania Hospital. His career as a printer made Franklin wealthy and well-respected. When he retired in 1748, he devoted himself to politics and scientific experiments. His most famous work, on electricity, exemplified Enlightenment principles. Franklin observed that lightning strikes tended to hit metal objects and reasoned that he could therefore direct lightning through the placement of metal objects during an electrical storm. He used this knowledge to advocate the use of lightning rods: metal poles connected to wires directing lightning’s electrical charge into the ground and saving wooden homes in cities like Philadelphia from catastrophic fires. He published his findings in 1751, in Experiments and Observations on Electricity . Franklin also wrote of his “rags to riches” tale, his Memoir , in the 1770s and 1780s. This story laid the foundation for the American Dream of upward social mobility. THE FOUNDING OF GEORGIA The reach of Enlightenment thought was both broad and deep. In the 1730s, it even prompted the founding of a new colony. Having witnessed the terrible conditions of debtors’ prison, as well as the results of releasing penniless debtors onto the streets of London, James Oglethorpe, a member of Parliament and advocate of social reform, petitioned King George II for a charter to start a new colony. George II, understanding the strategic advantage of a British colony standing as a buffer between South Carolina and Spanish Florida, granted the charter to Oglethorpe and twenty like-minded proprietors in 1732. Oglethorpe led the settlement of the colony, which was called Georgia in honor of the king. In 1733, he and 113 immigrants arrived on the ship Anne . Over the next decade, Parliament funded the migration of twenty-five hundred settlers, making Georgia the only government-funded colonial project. Oglethorpe’s vision for Georgia followed the ideals of the Age of Reason , seeing it as a place for England’s “worthy poor” to start anew. To encourage industry, he gave each male immigrant fifty acres of land, tools, and a year’s worth of supplies. In Savannah, the Oglethorpe Plan provided for a utopia: “an agrarian model of sustenance while sustaining egalitarian values holding all men as equal.” Oglethorpe’s vision called for alcohol and slavery to be banned. However, colonists who relocated from other colonies, especially South Carolina, disregarded these prohibitions. Despite its proprietors’ early vision of a colony guided by Enlightenment ideals and free of slavery, by the 1750s, Georgia was producing quantities of rice grown and harvested by the enslaved. 4.5 Wars for Empire Learning Objectives By the end of this section, you will be able to: Describe the wars for empire Analyze the significance of these conflicts Wars for empire composed a final link connecting the Atlantic sides of the British Empire. Great Britain fought four separate wars against Catholic France from the late 1600s to the mid-1700s. Another war, the War of Jenkins’ Ear, pitted Britain against Spain. These conflicts for control of North America also helped colonists forge important alliances with native peoples, as different tribes aligned themselves with different European powers. GENERATIONS OF WARFARE Generations of British colonists grew up during a time when much of North America, especially the Northeast, engaged in war. Colonists knew war firsthand. In the eighteenth century, fighting was seasonal. Armies mobilized in the spring, fought in the summer, and retired to winter quarters in the fall. The British army imposed harsh discipline on its soldiers, who were drawn from the poorer classes, to ensure they did not step out of line during engagements. If they did, their officers would kill them. On the battlefield, armies dressed in bright uniforms to advertise their bravery and lack of fear. They stood in tight formation and exchanged volleys with the enemy. They often feared their officers more than the enemy. Most imperial conflicts had both American and European fronts, leaving us with two names for each war. For instance, King William’s War (1688–1697) is also known as the War of the League of Augsburg. In America, the bulk of the fighting in this conflict took place between New England and New France. The war proved inconclusive, with no clear victor ( Figure 4.16 ). Queen Anne’s War (1702–1713) is also known as the War of Spanish Succession. England fought against both Spain and France over who would ascend the Spanish throne after the last of the Hapsburg rulers died. In North America, fighting took place in Florida, New England, and New France. In Canada, the French prevailed but lost Acadia and Newfoundland; however, the victory was again not decisive because the English failed to take Quebec, which would have given them control of Canada. This conflict is best remembered in the United States for the French and Native raid against Deerfield, Massachusetts, in 1704. A small French force, combined with a native group made up of Catholic Mohawks and Abenaki (Pocumtucs), attacked the frontier outpost of Deerfield, killing scores and taking 112 prisoners. Among the captives was the seven-year-old daughter of Deerfield’s minister John Williams, named Eunice. She was held by the Mohawks for years as her family tried to get her back, and became assimilated into the tribe. To the horror of the Puritan leaders, when she grew up Eunice married a Mohawk and refused to return to New England. In North America, possession of Georgia and trade with the interior was the focus of the War of Jenkins’ Ear (1739–1742), a conflict between Britain and Spain over contested claims to the land occupied by the fledgling colony between South Carolina and Florida. The war got its name from an incident in 1731 in which a Spanish Coast Guard captain severed the ear of British captain Robert Jenkins as punishment for raiding Spanish ships in Panama. Jenkins fueled the growing animosity between England and Spain by presenting his ear to Parliament and stirring up British public outrage. More than anything else, the War of Jenkins’ Ear disrupted the Atlantic trade, a situation that hurt both Spain and Britain and was a major reason the war came to a close in 1742. Georgia, founded six years earlier, remained British and a buffer against Spanish Florida. King George’s War (1744–1748), known in Europe as the War of Austrian Succession (1740–1748), was fought in the northern colonies and New France. In 1745, the British took the massive French fortress at Louisbourg on Cape Breton Island, Nova Scotia ( Figure 4.17 ). However, three years later, under the terms of the Treaty of Aix-la-Chapelle, Britain relinquished control of the fortress to the French. Once again, war resulted in an incomplete victory for both Britain and France. THE FRENCH AND INDIAN WAR The final imperial war, the French and Indian War (1754–1763), known as the Seven Years’ War (1756–1763) in Europe, proved to be the decisive contest between Britain and France in America. It began over rival claims along the frontier in present-day western Pennsylvania. Well-connected planters from Virginia faced stagnant tobacco prices and hoped expanding into these western lands would stabilize their wealth and status. Some of them established the Ohio Company of Virginia in 1748, and the British crown granted the company half a million acres in 1749. However, the French also claimed the lands of the Ohio Company, and to protect the region they established Fort Duquesne in 1754, where the Ohio, Monongahela, and Allegheny Rivers met. The war began in May 1754 because of these competing claims between Britain and France. Twenty-two-year-old Virginian George Washington, a surveyor whose family helped to found the Ohio Company, gave the command to fire on French soldiers near present-day Uniontown, Pennsylvania. This incident on the Pennsylvania frontier proved to be a decisive event that led to imperial war. For the next decade, fighting took place along the frontier of New France and British America from Virginia to Maine. The war also spread to Europe as France and Britain looked to gain supremacy in the Atlantic World. The British fared poorly in the first years of the war. In 1754, the French and their native allies forced Washington to surrender at Fort Necessity, a hastily built fort constructed after his attack on the French. In 1755, Britain dispatched General Edward Braddock to the colonies to take Fort Duquesne. The French, aided by the Potawotomis, Ottawas, Shawnees, and Delawares, ambushed the fifteen hundred British soldiers and Virginia militia who marched to the fort. The attack sent panic through the British force, and hundreds of British soldiers and militiamen died, including General Braddock. The campaign of 1755 proved to be a disaster for the British. In fact, the only British victory that year was the capture of Nova Scotia. In 1756 and 1757, Britain suffered further defeats with the fall of Fort Oswego and Fort William Henry ( Figure 4.18 ). The war began to turn in favor of the British in 1758, due in large part to the efforts of William Pitt, a very popular member of Parliament. Pitt pledged huge sums of money and resources to defeating the hated Catholic French, and Great Britain spent part of the money on bounties paid to new young recruits in the colonies, helping invigorate the British forces. In 1758, the Iroquois, Delaware, and Shawnee signed the Treaty of Easton, aligning themselves with the British in return for some contested land around Pennsylvania and Virginia. In 1759, the British took Quebec, and in 1760, Montreal. The French empire in North America had crumbled. The war continued until 1763, when the French signed the Treaty of Paris . This treaty signaled a dramatic reversal of fortune for France. Indeed, New France, which had been founded in the early 1600s, ceased to exist. The British Empire had now gained mastery over North America. The Empire not only gained New France under the treaty; it also acquired French sugar islands in the West Indies, French trading posts in India, and French-held posts on the west coast of Africa. Great Britain’s victory in the French and Indian War meant that it had become a truly global empire. British colonists joyously celebrated, singing the refrain of “Rule, Britannia! / Britannia, rule the waves! / Britons never, never, never shall be slaves!” In the American colonies, ties with Great Britain were closer than ever. Professional British soldiers had fought alongside Anglo-American militiamen, forging a greater sense of shared identity. With Great Britain’s victory, colonial pride ran high as colonists celebrated their identity as British subjects. This last of the wars for empire, however, also sowed the seeds of trouble. The war led Great Britain deeply into debt, and in the 1760s and 1770s, efforts to deal with the debt through imperial reforms would have the unintended consequence of causing stress and strain that threatened to tear the Empire apart.
microbiology
Summary 17.1 Physical Defenses Nonspecific innate immunity provides a first line of defense against infection by nonspecifically blocking entry of microbes and targeting them for destruction or removal from the body. The physical defenses of innate immunity include physical barriers, mechanical actions that remove microbes and debris, and the microbiome, which competes with and inhibits the growth of pathogens. The skin, mucous membranes, and endothelia throughout the body serve as physical barriers that prevent microbes from reaching potential sites of infection. Tight cell junctions in these tissues prevent microbes from passing through. Microbes trapped in dead skin cells or mucus are removed from the body by mechanical actions such as shedding of skin cells, mucociliary sweeping, coughing, peristalsis , and flushing of bodily fluids (e.g., urination, tears) The resident microbiota provide a physical defense by occupying available cellular binding sites and competing with pathogens for available nutrients. 17.2 Chemical Defenses Numerous chemical mediators produced endogenously and exogenously exhibit nonspecific antimicrobial functions. Many chemical mediators are found in body fluids such as sebum, saliva, mucus, gastric and intestinal fluids, urine, tears, cerumen, and vaginal secretions. Antimicrobial peptides (AMPs) found on the skin and in other areas of the body are largely produced in response to the presence of pathogens. These include dermcidin, cathelicidin, defensins, histatins, and bacteriocins. Plasma contains various proteins that serve as chemical mediators, including acute-phase proteins , complement proteins , and cytokines . The complement system involves numerous precursor proteins that circulate in plasma. These proteins become activated in a cascading sequence in the presence of microbes, resulting in the opsonization of pathogens, chemoattraction of leukocytes, induction of inflammation, and cytolysis through the formation of a membrane attack complex (MAC) . Cytokines are proteins that facilitate various nonspecific responses by innate immune cells, including production of other chemical mediators, cell proliferation, cell death, and differentiation. Cytokines play a key role in the inflammatory response, triggering production of inflammation-eliciting mediators such as acute-phase proteins, histamine , leukotrienes, prostaglandins , and bradykinin . 17.3 Cellular Defenses The formed elements of the blood include red blood cells ( erythrocytes ), white blood cells ( leukocytes ), and platelets (thrombocytes ). Of these, leukocytes are primarily involved in the immune response. All formed elements originate in the bone marrow as stem cells (HSCs) that differentiate through hematopoiesis . Granulocytes are leukocytes characterized by a lobed nucleus and granules in the cytoplasm. These include neutrophils (PMNs) , eosinophils , and basophils . Neutrophils are the leukocytes found in the largest numbers in the bloodstream and they primarily fight bacterial infections. Eosinophils target parasitic infections. Eosinophils and basophils are involved in allergic reactions. Both release histamine and other proinflammatory compounds from their granules upon stimulation. Mast cells function similarly to basophils but can be found in tissues outside the bloodstream. Natural killer ( NK ) cells are lymphocytes that recognize and kill abnormal or infected cells by releasing proteins that trigger apoptosis. Monocytes are large, mononuclear leukocytes that circulate in the bloodstream. They may leave the bloodstream and take up residence in body tissues, where they differentiate and become tissue-specific macrophages and dendritic cells . 17.4 Pathogen Recognition and Phagocytosis Phagocytes are cells that recognize pathogens and destroy them through phagocytosis. Recognition often takes place by the use of phagocyte receptors that bind molecules commonly found on pathogens, known as pathogen-associated molecular patterns (PAMPs) . The receptors that bind PAMPs are called pattern recognition receptors , or PRRs . Toll-like receptors ( TLRs ) are one type of PRR found on phagocytes. Extravasation of white blood cells from the bloodstream into infected tissue occurs through the process of transendothelial migration . Phagocytes degrade pathogens through phagocytosis , which involves engulfing the pathogen, killing and digesting it within a phagolysosome , and then excreting undigested matter. 17.5 Inflammation and Fever Inflammation results from the collective response of chemical mediators and cellular defenses to an injury or infection. Acute inflammation is short lived and localized to the site of injury or infection. Chronic inflammation occurs when the inflammatory response is unsuccessful, and may result in the formation of granulomas (e.g., with tuberculosis) and scarring (e.g., with hepatitis C viral infections and liver cirrhosis). The five cardinal signs of inflammation are erythema , edema , heat, pain, and altered function. These largely result from innate responses that draw increased blood flow to the injured or infected tissue. Fever is a system-wide sign of inflammation that raises the body temperature and stimulates the immune response. Both inflammation and fever can be harmful if the inflammatory response is too severe.
Chapter Outline 17.1 Physical Defenses 17.2 Chemical Defenses 17.3 Cellular Defenses 17.4 Pathogen Recognition and Phagocytosis 17.5 Inflammation and Fever Introduction Despite relatively constant exposure to pathogenic microbes in the environment, humans do not generally suffer from constant infection or disease. Under most circumstances, the body is able to defend itself from the threat of infection thanks to a complex immune system designed to repel, kill, and expel disease-causing invaders. Immunity as a whole can be described as two interrelated parts: nonspecific innate immunity , which is the subject of this chapter, and specific adaptive host defenses, which are discussed in the next chapter. The nonspecific innate immune response provides a first line of defense that can often prevent infections from gaining a solid foothold in the body. These defenses are described as nonspecific because they do not target any specific pathogen; rather, they defend against a wide range of potential pathogens. They are called innate because they are built-in mechanisms of the human organism. Unlike the specific adaptive defenses, they are not acquired over time and they have no “memory” (they do not improve after repeated exposures to specific pathogens). Broadly speaking, nonspecific innate defenses provide an immediate (or very rapid) response against potential pathogens. However, these responses are neither perfect nor impenetrable. They can be circumvented by pathogens on occasion, and sometimes they can even cause damage to the body, contributing to the signs and symptoms of infection ( Figure 17.1 ).
[ { "answer": { "ans_choice": 1, "ans_text": "B" }, "bloom": null, "hl_context": "<hl> Nonspecific innate immunity can be characterized as a multifaceted system of defenses that targets invading pathogens in a nonspecific manner . <hl> In this chapter , we have divided the numerous defenses that make up this system into three categories : physical defenses , chemical defenses , and cellular defenses . However , it is important to keep in mind that these defenses do not function independently , and the categories often overlap . Table 17.1 provides an overview of the nonspecific defenses discussed in this chapter .", "hl_sentences": "Nonspecific innate immunity can be characterized as a multifaceted system of defenses that targets invading pathogens in a nonspecific manner .", "question": { "cloze_format": "___ best describes the innate nonspecific immune system.", "normal_format": "Which of the following best describes the innate nonspecific immune system?", "question_choices": [ "a targeted and highly specific response to a single pathogen or molecule", "a generalized and nonspecific set of defenses against a class or group of pathogens", "a set of barrier mechanisms that adapts to specific pathogens after repeated exposure", "the production of antibody molecules against pathogens" ], "question_id": "fs-id1172100760283", "question_text": "Which of the following best describes the innate nonspecific immune system?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 0, "ans_text": "A" }, "bloom": null, "hl_context": "The topmost layer of skin , the epidermis , consists of cells that are packed with keratin . These dead cells remain as a tightly connected , dense layer of protein-filled cell husks on the surface of the skin . The keratin makes the skin ’ s surface mechanically tough and resistant to degradation by bacterial enzymes . <hl> Fatty acids on the skin ’ s surface create a dry , salty , and acidic environment that inhibits the growth of some microbes and is highly resistant to breakdown by bacterial enzymes . <hl> <hl> In addition , the dead cells of the epidermis are frequently shed , along with any microbes that may be clinging to them . <hl> Shed skin cells are continually replaced with new cells from below , providing a new barrier that will soon be shed in the same way .", "hl_sentences": "Fatty acids on the skin ’ s surface create a dry , salty , and acidic environment that inhibits the growth of some microbes and is highly resistant to breakdown by bacterial enzymes . In addition , the dead cells of the epidermis are frequently shed , along with any microbes that may be clinging to them .", "question": { "cloze_format": "The ___ constantly sheds dead cells along with any microbes that may be attached to those cells.", "normal_format": "Which of the following constantly sheds dead cells along with any microbes that may be attached to those cells?", "question_choices": [ "epidermis", "dermis", "hypodermis", "mucous membrane" ], "question_id": "fs-id1172100959355", "question_text": "Which of the following constantly sheds dead cells along with any microbes that may be attached to those cells?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 2, "ans_text": "C" }, "bloom": null, "hl_context": "<hl> The epithelial cells lining the urogenital tract , blood vessels , lymphatic vessels , and certain other tissues are known as endothelia . <hl> <hl> These tightly packed cells provide a particularly effective frontline barrier against invaders . <hl> <hl> The endothelia of the blood-brain barrier , for example , protect the central nervous system ( CNS ) , which consists of the brain and the spinal cord . <hl> The CNS is one of the most sensitive and important areas of the body , as microbial infection of the CNS can quickly lead to serious and often fatal inflammation . <hl> The cell junctions in the blood vessels traveling through the CNS are some of the tightest and toughest in the body , preventing any transient microbes in the bloodstream from entering the CNS . <hl> This keeps the cerebrospinal fluid that surrounds and bathes the brain and spinal cord sterile under normal conditions .", "hl_sentences": "The epithelial cells lining the urogenital tract , blood vessels , lymphatic vessels , and certain other tissues are known as endothelia . These tightly packed cells provide a particularly effective frontline barrier against invaders . The endothelia of the blood-brain barrier , for example , protect the central nervous system ( CNS ) , which consists of the brain and the spinal cord . The cell junctions in the blood vessels traveling through the CNS are some of the tightest and toughest in the body , preventing any transient microbes in the bloodstream from entering the CNS .", "question": { "cloze_format": "___ uses a particularly dense suite of tight junctions to prevent microbes from entering the underlying tissue.", "normal_format": "Which of the following uses a particularly dense suite of tight junctions to prevent microbes from entering the underlying tissue?", "question_choices": [ "the mucociliary escalator", "the epidermis", "the blood-brain barrier", "the urethra" ], "question_id": "fs-id1172100827434", "question_text": "Which of the following uses a particularly dense suite of tight junctions to prevent microbes from entering the underlying tissue?" }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 0, "ans_text": "A" }, "bloom": null, "hl_context": "<hl> Cytokines are soluble proteins that act as communication signals between cells . <hl> <hl> In a nonspecific innate immune response , various cytokines may be released to stimulate production of chemical mediators or other cell functions , such as cell proliferation , cell differentiation , inhibition of cell division , apoptosis , and chemotaxis . <hl>", "hl_sentences": "Cytokines are soluble proteins that act as communication signals between cells . In a nonspecific innate immune response , various cytokines may be released to stimulate production of chemical mediators or other cell functions , such as cell proliferation , cell differentiation , inhibition of cell division , apoptosis , and chemotaxis .", "question": { "cloze_format": "___ serve as chemical signals between cells and stimulate a wide range of nonspecific defenses.", "normal_format": "Which of the following serve as chemical signals between cells and stimulate a wide range of nonspecific defenses?", "question_choices": [ "cytokines", "antimicrobial peptides", "complement proteins", "antibodies" ], "question_id": "fs-id1172101856437", "question_text": "Which of the following serve as chemical signals between cells and stimulate a wide range of nonspecific defenses?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 3, "ans_text": "D" }, "bloom": null, "hl_context": "<hl> A family of AMPs called defensins can be produced by epithelial cells throughout the body as well as by cellular defenses such as macrophages and neutrophils ( see Cellular Defenses ) . <hl> <hl> Defensins may be secreted or act inside host cells ; they combat microorganisms by damaging their plasma membranes . <hl> <hl> AMPs called bacteriocins are produced exogenously by certain members of the resident microbiota within the gastrointestinal tract . <hl> The genes coding for these types of AMPs are often carried on plasmids and can be passed between different species within the resident microbiota through lateral or horizontal gene transfer . AMPs may induce cell damage in microorganisms in a variety of ways , including by inflicting damage to membranes , destroying DNA and RNA , or interfering with cell-wall synthesis . <hl> Depending on the specific antimicrobial mechanism , a particular AMP may inhibit only certain groups of microbes ( e . g . , gram-positive or gram-negative bacteria ) or it may be more broadly effective against bacteria , fungi , protozoa , and viruses . <hl> Many AMPs are found on the skin , but they can also be found in other regions of the body .", "hl_sentences": "A family of AMPs called defensins can be produced by epithelial cells throughout the body as well as by cellular defenses such as macrophages and neutrophils ( see Cellular Defenses ) . Defensins may be secreted or act inside host cells ; they combat microorganisms by damaging their plasma membranes . AMPs called bacteriocins are produced exogenously by certain members of the resident microbiota within the gastrointestinal tract . Depending on the specific antimicrobial mechanism , a particular AMP may inhibit only certain groups of microbes ( e . g . , gram-positive or gram-negative bacteria ) or it may be more broadly effective against bacteria , fungi , protozoa , and viruses .", "question": { "cloze_format": "Bacteriocins and defensins are types of ___.", "normal_format": "Bacteriocins and defensins are types of which of the following?", "question_choices": [ "leukotrienes", "cytokines", "inflammation-eliciting mediators", "antimicrobial peptides" ], "question_id": "fs-id1172101911308", "question_text": "Bacteriocins and defensins are types of which of the following?" }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 1, "ans_text": "B" }, "bloom": null, "hl_context": "<hl> Fluids produced by the skin include examples of both endogenous and exogenous mediators . <hl> <hl> Sebaceous glands in the dermis secrete an oil called sebum that is released onto the skin surface through hair follicles . <hl> This sebum is an endogenous mediator , providing an additional layer of defense by helping seal off the pore of the hair follicle , preventing bacteria on the skin ’ s surface from invading sweat glands and surrounding tissue ( Figure 17.8 ) . Certain members of the microbiome , such as the bacterium Propionibacterium acnes and the fungus Malassezia , among others , can use lipase enzymes to degrade sebum , using it as a food source . This produces oleic acid , which creates a mildly acidic environment on the surface of the skin that is inhospitable to many pathogenic microbes . Oleic acid is an example of an exogenously produced mediator because it is produced by resident microbes and not directly by body cells .", "hl_sentences": "Fluids produced by the skin include examples of both endogenous and exogenous mediators . Sebaceous glands in the dermis secrete an oil called sebum that is released onto the skin surface through hair follicles .", "question": { "cloze_format": "___ is a chemical mediator that is secreted onto the surface of the skin.", "normal_format": "Which of the following chemical mediators is secreted onto the surface of the skin?", "question_choices": [ "cerumen", "sebum", "gastric acid", "prostaglandin" ], "question_id": "fs-id1172097305753", "question_text": "Which of the following chemical mediators is secreted onto the surface of the skin?" }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 2, "ans_text": "C" }, "bloom": null, "hl_context": "Many of the chemical mediators discussed in this section contribute in some way to inflammation and fever , which are nonspecific immune responses discussed in more detail in Inflammation and Fever . Cytokines stimulate the production of acute-phase proteins such as C-reactive protein and mannose-binding lectin in the liver . <hl> These acute-phase proteins act as opsonins , activating complement cascades through the lectin pathway . <hl> <hl> The lectin activation pathway is similar to the classical pathway , but it is triggered by the binding of mannose-binding lectin , an acute-phase protein , to carbohydrates on the microbial surface . <hl> Like other acute-phase proteins , lectins are produced by liver cells and are commonly upregulated in response to inflammatory signals received by the body during an infection ( Figure 17.9 ) .", "hl_sentences": "These acute-phase proteins act as opsonins , activating complement cascades through the lectin pathway . The lectin activation pathway is similar to the classical pathway , but it is triggered by the binding of mannose-binding lectin , an acute-phase protein , to carbohydrates on the microbial surface .", "question": { "cloze_format": "The complement activation pathway that is triggered by the binding of an acute-phase protein to a pathogen is called ___.", "normal_format": "Which complement activation pathway is triggered by the binding of an acute-phase protein to a pathogen?", "question_choices": [ "classical", "alternate", "lectin", "cathelicidin" ], "question_id": "fs-id1172101756535", "question_text": "Identify the complement activation pathway that is triggered by the binding of an acute-phase protein to a pathogen." }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 1, "ans_text": "B" }, "bloom": null, "hl_context": "<hl> Certain cytokines also stimulate the production of prostaglandins , chemical mediators that promote the inflammatory effects of kinins and histamines . <hl> Prostaglandins can also help to set the body temperature higher , leading to fever , which promotes the activities of white blood cells and slightly inhibits the growth of pathogenic microbes ( see Inflammation and Fever ) . <hl> In addition to histamine , mast cells may release other chemical mediators , such as leukotrienes . <hl> <hl> Leukotrienes are lipid-based proinflammatory mediators that are produced from the metabolism of arachidonic acid in the cell membrane of leukocytes and tissue cells . <hl> <hl> Compared with the proinflammatory effects of histamine , those of leukotrienes are more potent and longer lasting . <hl> Together , these chemical mediators can induce coughing , vomiting , and diarrhea , which serve to expel pathogens from the body .", "hl_sentences": "Certain cytokines also stimulate the production of prostaglandins , chemical mediators that promote the inflammatory effects of kinins and histamines . In addition to histamine , mast cells may release other chemical mediators , such as leukotrienes . Leukotrienes are lipid-based proinflammatory mediators that are produced from the metabolism of arachidonic acid in the cell membrane of leukocytes and tissue cells . Compared with the proinflammatory effects of histamine , those of leukotrienes are more potent and longer lasting .", "question": { "cloze_format": "Histamine, leukotrienes, prostaglandins, and bradykinin are examples of ___.", "normal_format": "Histamine, leukotrienes, prostaglandins, and bradykinin are examples of which of the following?", "question_choices": [ "chemical mediators primarily found in the digestive system", "chemical mediators that promote inflammation", "antimicrobial peptides found on the skin", "complement proteins that form MACs" ], "question_id": "fs-id1172097182412", "question_text": "Histamine, leukotrienes, prostaglandins, and bradykinin are examples of which of the following?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 2, "ans_text": "C" }, "bloom": null, "hl_context": "In the previous section , we discussed some of the chemical mediators found in plasma , the fluid portion of blood . The nonfluid portion of blood consists of various types of formed elements , so called because they are all formed from the same stem cells found in bone marrow . <hl> The three major categories of formed elements are : red blood cells ( RBCs ) , also called erythrocyte s ; platelets , also called thrombocytes ; and white blood cells ( WBCs ) , also called leukocytes . <hl>", "hl_sentences": "The three major categories of formed elements are : red blood cells ( RBCs ) , also called erythrocyte s ; platelets , also called thrombocytes ; and white blood cells ( WBCs ) , also called leukocytes .", "question": { "cloze_format": "White blood cells are also referred to as ___ .", "normal_format": "White blood cells are also referred to as which of the following?", "question_choices": [ "platelets", "erythrocytes", "leukocytes", "megakaryocytes" ], "question_id": "fs-id1172100621865", "question_text": "White blood cells are also referred to as which of the following?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 1, "ans_text": "B" }, "bloom": null, "hl_context": "<hl> All of the formed elements of blood are derived from pluripotent hematopoietic stem cells ( HSCs ) in the bone marrow . <hl> <hl> As the HSCs make copies of themselves in the bone marrow , individual cells receive different cues from the body that control how they develop and mature . <hl> As a result , the HSCs differentiate into different types of blood cells that , once mature , circulate in peripheral blood . <hl> This process of differentiation , called hematopoiesis , is shown in more detail in Figure 17.12 . <hl>", "hl_sentences": "All of the formed elements of blood are derived from pluripotent hematopoietic stem cells ( HSCs ) in the bone marrow . As the HSCs make copies of themselves in the bone marrow , individual cells receive different cues from the body that control how they develop and mature . This process of differentiation , called hematopoiesis , is shown in more detail in Figure 17.12 .", "question": { "cloze_format": "Hematopoiesis occurs in the ___.", "normal_format": "Hematopoiesis occurs in which of the following?", "question_choices": [ "liver", "bone marrow", "kidneys", "central nervous system" ], "question_id": "fs-id1172100735358", "question_text": "Hematopoiesis occurs in which of the following?" }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 3, "ans_text": "D" }, "bloom": null, "hl_context": "In terms of sheer numbers , the vast majority of HSCs become erythrocytes . Much smaller numbers become leukocytes and platelets . <hl> Leukocytes can be further subdivided into granulocytes , which are characterized by numerous granules visible in the cytoplasm , and agranulocytes , which lack granules . <hl> Figure 17.13 provides an overview of the various types of formed elements , including their relative numbers , primary function , and lifespans .", "hl_sentences": "Leukocytes can be further subdivided into granulocytes , which are characterized by numerous granules visible in the cytoplasm , and agranulocytes , which lack granules .", "question": { "cloze_format": "Granulocytes are a ___ type of cell.", "normal_format": "Granulocytes are which type of cell?", "question_choices": [ "lymphocyte", "erythrocyte", "megakaryocyte", "leukocyte" ], "question_id": "fs-id1172098258754", "question_text": "Granulocytes are which type of cell?" }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 0, "ans_text": "A" }, "bloom": null, "hl_context": "As described in the previous section , opsonization of pathogens by antibody ; complement factors C1q , C3b , and C4b ; and lectins can assist phagocytic cells in recognition of pathogens and attachment to initiate phagocytosis . However , not all pathogen recognition is opsonin dependent . <hl> Phagocytes can also recognize molecular structures that are common to many groups of pathogenic microbes . <hl> <hl> Such structures are called pathogen-associated molecular patterns ( PAMPs ) . <hl> Common PAMPs include the following :", "hl_sentences": "Phagocytes can also recognize molecular structures that are common to many groups of pathogenic microbes . Such structures are called pathogen-associated molecular patterns ( PAMPs ) .", "question": { "cloze_format": "PAMPs would be found on the surface of ___.", "normal_format": "PAMPs would be found on the surface of which of the following?", "question_choices": [ "pathogen", "phagocyte", "skin cell", "blood vessel wall" ], "question_id": "fs-id1172100928824", "question_text": "PAMPs would be found on the surface of which of the following?" }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 0, "ans_text": "A" }, "bloom": null, "hl_context": "<hl> The structures that allow phagocytic cells to detect PAMPs are called pattern recognition receptors ( PRRs ) . <hl> <hl> One group of PRRs is the toll-like receptors ( TLRs ) , which bind to various PAMPs and communicate with the nucleus of the phagocyte to elicit a response . <hl> Many TLRs ( and other PRRs ) are located on the surface of a phagocyte , but some can also be found embedded in the membranes of interior compartments and organelles ( Figure 17.20 ) . These interior PRRs can be useful for the binding and recognition of intracellular pathogens that may have gained access to the inside of the cell before phagocytosis could take place . Viral nucleic acids , for example , might encounter an interior PRR , triggering production of the antiviral cytokine interferon .", "hl_sentences": "The structures that allow phagocytic cells to detect PAMPs are called pattern recognition receptors ( PRRs ) . One group of PRRs is the toll-like receptors ( TLRs ) , which bind to various PAMPs and communicate with the nucleus of the phagocyte to elicit a response .", "question": { "cloze_format": "________ on phagocytes bind to PAMPs on bacteria, which triggers the uptake and destruction of the bacterial pathogens?", "normal_format": "What on phagocytes bind to PAMPs on bacteria, which triggers the uptake and destruction of the bacterial pathogens? ", "question_choices": [ "PRRs", "AMPs", "PAMPs", "PMNs" ], "question_id": "fs-id1172100637317", "question_text": "________ on phagocytes bind to PAMPs on bacteria, which triggers the uptake and destruction of the bacterial pathogens?" }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 2, "ans_text": "C" }, "bloom": null, "hl_context": "<hl> Although each complement activation pathway is initiated in a different way , they all provide the same protective outcomes : opsonization , inflammation , chemotaxis , and cytolysis . <hl> <hl> The term opsonization refers to the coating of a pathogen by a chemical substance ( called an opsonin ) that allows phagocytic cells to recognize , engulf , and destroy it more easily . <hl> Opsonins from the complement cascade include C1q , C3b , and C4b . Additional important opsonins include mannose-binding proteins and antibodies . The complement fragments C3a and C5a are well-characterized anaphylatoxins with potent proinflammatory functions . Anaphylatoxins activate mast cells , causing degranulation and the release of inflammatory chemical signals , including mediators that cause vasodilation and increased vascular permeability . C5a is also one of the most potent chemoattractants for neutrophils and other white blood cells , cellular defenses that will be discussed in the next section .", "hl_sentences": "Although each complement activation pathway is initiated in a different way , they all provide the same protective outcomes : opsonization , inflammation , chemotaxis , and cytolysis . The term opsonization refers to the coating of a pathogen by a chemical substance ( called an opsonin ) that allows phagocytic cells to recognize , engulf , and destroy it more easily .", "question": { "cloze_format": "The model of pathogen recognition for opsononin-dependent phagocytosis is best descrbed in that ___.", "normal_format": "Which of the following best characterizes the mode of pathogen recognition for opsonin-dependent phagocytosis?", "question_choices": [ "Opsonins produced by a pathogen attract phagocytes through chemotaxis.", "A PAMP on the pathogen’s surface is recognized by a phagocyte’s toll-like receptors.", "A pathogen is first coated with a molecule such as a complement protein, which allows it to be recognized by phagocytes.", "A pathogen is coated with a molecule such as a complement protein that immediately lyses the cell." ], "question_id": "fs-id1172096159045", "question_text": "Which of the following best characterizes the mode of pathogen recognition for opsonin-dependent phagocytosis?" }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 1, "ans_text": "B" }, "bloom": null, "hl_context": "An early , if not immediate , response to tissue injury is acute inflammation . Immediately following an injury , vasoconstriction of blood vessels will occur to minimize blood loss . The amount of vasoconstriction is related to the amount of vascular injury , but it is usually brief . Vasoconstriction is followed by vasodilation and increased vascular permeability , as a direct result of the release of histamine from resident mast cells . Increased blood flow and vascular permeability can dilute toxins and bacterial products at the site of injury or infection . <hl> They also contribute to the five observable signs associated with the inflammatory response : erythema ( redness ) , edema ( swelling ) , heat , pain , and altered function . <hl> Vasodilation and increased vascular permeability are also associated with an influx of phagocytes at the site of injury and / or infection . This can enhance the inflammatory response because phagocytes may release proinflammatory chemicals when they are activated by cellular distress signals released from damaged cells , by PAMPs , or by opsonins on the surface of pathogens . Activation of the complement system can further enhance the inflammatory response through the production of the anaphylatoxin C5a . Figure 17.23 illustrates a typical case of acute inflammation at the site of a skin wound .", "hl_sentences": "They also contribute to the five observable signs associated with the inflammatory response : erythema ( redness ) , edema ( swelling ) , heat , pain , and altered function .", "question": { "cloze_format": "___ refers to swelling as a result of inflammation.", "normal_format": "Which refers to swelling as a result of inflammation?", "question_choices": [ "erythema", "edema", "granuloma", "vasodilation" ], "question_id": "fs-id1172098647252", "question_text": "Which refers to swelling as a result of inflammation?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 0, "ans_text": "A" }, "bloom": null, "hl_context": "<hl> An early , if not immediate , response to tissue injury is acute inflammation . <hl> Immediately following an injury , vasoconstriction of blood vessels will occur to minimize blood loss . The amount of vasoconstriction is related to the amount of vascular injury , but it is usually brief . Vasoconstriction is followed by vasodilation and increased vascular permeability , as a direct result of the release of histamine from resident mast cells . Increased blood flow and vascular permeability can dilute toxins and bacterial products at the site of injury or infection . They also contribute to the five observable signs associated with the inflammatory response : erythema ( redness ) , edema ( swelling ) , heat , pain , and altered function . Vasodilation and increased vascular permeability are also associated with an influx of phagocytes at the site of injury and / or infection . This can enhance the inflammatory response because phagocytes may release proinflammatory chemicals when they are activated by cellular distress signals released from damaged cells , by PAMPs , or by opsonins on the surface of pathogens . Activation of the complement system can further enhance the inflammatory response through the production of the anaphylatoxin C5a . Figure 17.23 illustrates a typical case of acute inflammation at the site of a skin wound .", "hl_sentences": "An early , if not immediate , response to tissue injury is acute inflammation .", "question": { "cloze_format": "The type of inflammation that occurs at the site of an injury or infection is ___.", "normal_format": "Which type of inflammation occurs at the site of an injury or infection?", "question_choices": [ "acute", "chronic", "endogenous", "exogenous" ], "question_id": "fs-id1172101039318", "question_text": "Which type of inflammation occurs at the site of an injury or infection?" }, "references_are_paraphrase": null } ]
17
17.1 Physical Defenses Learning Objectives Describe the various physical barriers and mechanical defenses that protect the human body against infection and disease Describe the role of microbiota as a first-line defense against infection and disease Clinical Focus Part 1 Angela, a 25-year-old female patient in the emergency department, is having some trouble communicating verbally because of shortness of breath. A nurse observes constriction and swelling of the airway and labored breathing. The nurse asks Angela if she has a history of asthma or allergies. Angela shakes her head no, but there is fear in her eyes. With some difficulty, she explains that her father died suddenly at age 27, when she was just a little girl, of a similar respiratory attack. The underlying cause had never been identified. What are some possible causes of constriction and swelling of the airway? What causes swelling of body tissues in general? Jump to the next Clinical Focus box. Nonspecific innate immunity can be characterized as a multifaceted system of defenses that targets invading pathogens in a nonspecific manner. In this chapter, we have divided the numerous defenses that make up this system into three categories: physical defenses, chemical defenses, and cellular defenses. However, it is important to keep in mind that these defenses do not function independently, and the categories often overlap. Table 17.1 provides an overview of the nonspecific defenses discussed in this chapter. Overview of Nonspecific Innate Immune Defenses Physical defenses Physical barriers Mechanical defenses Microbiome Chemical defenses Chemicals and enzymes in body fluids Antimicrobial peptides Plasma protein mediators Cytokines Inflammation-eliciting mediators Cellular defenses Granulocytes Agranulocytes Table 17.1 Physical defenses provide the body’s most basic form of nonspecific defense. They include physical barriers to microbes, such as the skin and mucous membranes, as well as mechanical defenses that physically remove microbes and debris from areas of the body where they might cause harm or infection. In addition, the microbiome provides a measure of physical protection against disease, as microbes of the normal microbiota compete with pathogens for nutrients and cellular binding sites necessary to cause infection. Physical Barriers Physical barriers play an important role in preventing microbes from reaching tissues that are susceptible to infection. At the cellular level, barriers consist of cells that are tightly joined to prevent invaders from crossing through to deeper tissue. For example, the endothelial cells that line blood vessels have very tight cell-to-cell junctions, blocking microbes from gaining access to the bloodstream. Cell junctions are generally composed of cell membrane proteins that may connect with the extracellular matrix or with complementary proteins from neighboring cells. Tissues in various parts of the body have different types of cell junctions . These include tight junctions, desmosomes, and gap junctions, as illustrated in Figure 17.2 . Invading microorganisms may attempt to break down these substances chemically, using enzymes such as proteases that can cause structural damage to create a point of entry for pathogens. The Skin Barrier One of the body’s most important physical barriers is the skin barrier , which is composed of three layers of closely packed cells. The thin upper layer is called the epidermis. A second, thicker layer, called the dermis, contains hair follicles, sweat glands, nerves, and blood vessels. A layer of fatty tissue called the hypodermis lies beneath the dermis and contains blood and lymph vessels ( Figure 17.3 ). The topmost layer of skin, the epidermis , consists of cells that are packed with keratin. These dead cells remain as a tightly connected, dense layer of protein-filled cell husks on the surface of the skin. The keratin makes the skin’s surface mechanically tough and resistant to degradation by bacterial enzymes. Fatty acids on the skin’s surface create a dry, salty, and acidic environment that inhibits the growth of some microbes and is highly resistant to breakdown by bacterial enzymes. In addition, the dead cells of the epidermis are frequently shed, along with any microbes that may be clinging to them. Shed skin cells are continually replaced with new cells from below, providing a new barrier that will soon be shed in the same way. Infections can occur when the skin barrier is compromised or broken. A wound can serve as a point of entry for opportunistic pathogens, which can infect the skin tissue surrounding the wound and possibly spread to deeper tissues. Case in Point Every Rose Has its Thorn Mike, a gardener from southern California, recently noticed a small red bump on his left forearm. Initially, he did not think much of it, but soon it grew larger and then ulcerated (opened up), becoming a painful lesion that extended across a large part of his forearm ( Figure 17.4 ). He went to an urgent care facility, where a physician asked about his occupation. When he said he was a landscaper, the physician immediately suspected a case of sporotrichosis , a type of fungal infection known as rose gardener’s disease because it often afflicts landscapers and gardening enthusiasts. Under most conditions, fungi cannot produce skin infections in healthy individuals. Fungi grow filaments known as hyphae, which are not particularly invasive and can be easily kept at bay by the physical barriers of the skin and mucous membranes. However, small wounds in the skin, such as those caused by thorns, can provide an opening for opportunistic pathogens like Sporothrix schenkii , a soil-dwelling fungus and the causative agent of rose gardener’s disease. Once it breaches the skin barrier, S. schenkii can infect the skin and underlying tissues, producing ulcerated lesions like Mike’s. Compounding matters, other pathogens may enter the infected tissue, causing secondary bacterial infections. Luckily, rose gardener’s disease is treatable. Mike’s physician wrote him a prescription for some antifungal drugs as well as a course of antibiotics to combat secondary bacterial infections. His lesions eventually healed, and Mike returned to work with a new appreciation for gloves and protective clothing. Mucous Membranes The mucous membrane s lining the nose, mouth, lungs, and urinary and digestive tracts provide another nonspecific barrier against potential pathogens. Mucous membranes consist of a layer of epithelial cells bound by tight junctions. The epithelial cells secrete a moist, sticky substance called mucus , which covers and protects the more fragile cell layers beneath it and traps debris and particulate matter, including microbes. Mucus secretions also contain antimicrobial peptides. In many regions of the body, mechanical actions serve to flush mucus (along with trapped or dead microbes) out of the body or away from potential sites of infection. For example, in the respiratory system, inhalation can bring microbes, dust, mold spores, and other small airborne debris into the body. This debris becomes trapped in the mucus lining the respiratory tract, a layer known as the mucociliary blanket. The epithelial cells lining the upper parts of the respiratory tract are called ciliated epithelial cells because they have hair-like appendages known as cilia. Movement of the cilia propels debris-laden mucus out and away from the lungs. The expelled mucus is then swallowed and destroyed in the stomach, or coughed up, or sneezed out ( Figure 17.5 ). This system of removal is often called the mucociliary escalator . The mucociliary escalator is such an effective barrier to microbes that the lungs, the lowermost (and most sensitive) portion of the respiratory tract, were long considered to be a sterile environment in healthy individuals. Only recently has research suggested that healthy lungs may have a small normal microbiota. Disruption of the mucociliary escalator by the damaging effects of smoking or diseases such as cystic fibrosis can lead to increased colonization of bacteria in the lower respiratory tract and frequent infections, which highlights the importance of this physical barrier to host defenses. Like the respiratory tract, the digestive tract is a portal of entry through which microbes enter the body, and the mucous membranes lining the digestive tract provide a nonspecific physical barrier against ingested microbes. The intestinal tract is lined with epithelial cells, interspersed with mucus-secreting goblet cells ( Figure 17.6 ). This mucus mixes with material received from the stomach, trapping foodborne microbes and debris. The mechanical action of peristalsis , a series of muscular contractions in the digestive tract, moves the sloughed mucus and other material through the intestines, rectum, and anus, excreting the material in feces. Endothelia The epithelial cells lining the urogenital tract, blood vessels, lymphatic vessels, and certain other tissues are known as endothelia . These tightly packed cells provide a particularly effective frontline barrier against invaders. The endothelia of the blood-brain barrier , for example, protect the central nervous system (CNS), which consists of the brain and the spinal cord. The CNS is one of the most sensitive and important areas of the body, as microbial infection of the CNS can quickly lead to serious and often fatal inflammation. The cell junctions in the blood vessels traveling through the CNS are some of the tightest and toughest in the body, preventing any transient microbes in the bloodstream from entering the CNS. This keeps the cerebrospinal fluid that surrounds and bathes the brain and spinal cord sterile under normal conditions. Check Your Understanding Describe how the mucociliary escalator functions. Name two places you would find endothelia. Mechanical Defenses In addition to physical barriers that keep microbes out, the body has a number of mechanical defenses that physically remove pathogens from the body, preventing them from taking up residence. We have already discussed several examples of mechanical defenses, including the shedding of skin cells, the expulsion of mucus via the mucociliary escalator, and the excretion of feces through intestinal peristalsis. Other important examples of mechanical defenses include the flushing action of urine and tears, which both serve to carry microbes away from the body. The flushing action of urine is largely responsible for the normally sterile environment of the urinary tract, which includes the kidneys, ureters, and urinary bladder. Urine passing out of the body washes out transient microorganisms, preventing them from taking up residence. The eyes also have physical barriers and mechanical mechanisms for preventing infections. The eyelashes and eyelids prevent dust and airborne microorganisms from reaching the surface of the eye. Any microbes or debris that make it past these physical barriers may be flushed out by the mechanical action of blinking, which bathes the eye in tears, washing debris away ( Figure 17.7 ). Check Your Understanding Name two mechanical defenses that protect the eyes. Microbiome In various regions of the body, resident microbiota serve as an important first-line defense against invading pathogens. Through their occupation of cellular binding sites and competition for available nutrients, the resident microbiota prevent the critical early steps of pathogen attachment and proliferation required for the establishment of an infection. For example, in the vagina , members of the resident microbiota compete with opportunistic pathogens like the yeast Candida . This competition prevents infections by limiting the availability of nutrients, thus inhibiting the growth of Candida , keeping its population in check. Similar competitions occur between the microbiota and potential pathogens on the skin, in the upper respiratory tract, and in the gastrointestinal tract. As will be discussed later in this chapter, the resident microbiota also contribute to the chemical defenses of the innate nonspecific host defenses. The importance of the normal microbiota in host defenses is highlighted by the increased susceptibility to infectious diseases when the microbiota is disrupted or eliminated. Treatment with antibiotics can significantly deplete the normal microbiota of the gastrointestinal tract, providing an advantage for pathogenic bacteria to colonize and cause diarrheal infection. In the case of diarrhea caused by Clostridium difficile , the infection can be severe and potentially lethal. One strategy for treating C. difficile infections is fecal transplantation , which involves the transfer of fecal material from a donor (screened for potential pathogens) into the intestines of the recipient patient as a method of restoring the normal microbiota and combating C. difficile infections. Table 17.2 provides a summary of the physical defenses discussed in this section. Physical Defenses of Nonspecific Innate Immunity Defense Examples Function Cellular barriers Skin, mucous membranes, endothelial cells Deny entry to pathogens Mechanical defenses Shedding of skin cells, mucociliary sweeping, peristalsis, flushing action of urine and tears Remove pathogens from potential sites of infection Microbiome Resident bacteria of the skin, upper respiratory tract, gastrointestinal tract, and genitourinary tract Compete with pathogens for cellular binding sites and nutrients Table 17.2 Check Your Understanding List two ways resident microbiota defend against pathogens. 17.2 Chemical Defenses Learning Objectives Describe how enzymes in body fluids provide protection against infection or disease List and describe the function of antimicrobial peptides, complement components, cytokines, and acute-phase proteins Describe similarities and differences among classic, alternate, and lectin complement pathways In addition to physical defenses, the innate nonspecific immune system uses a number of chemical mediators that inhibit microbial invaders. The term “chemical mediators” encompasses a wide array of substances found in various body fluids and tissues throughout the body. Chemical mediators may work alone or in conjunction with each other to inhibit microbial colonization and infection. Some chemical mediators are endogenously produced, meaning they are produced by human body cells; others are produced exogenously, meaning that they are produced by certain microbes that are part of the microbiome. Some mediators are produced continually, bathing the area in the antimicrobial substance; others are produced or activated primarily in response to some stimulus, such as the presence of microbes. Chemical and Enzymatic Mediators Found in Body Fluids Fluids produced by the skin include examples of both endogenous and exogenous mediators. Sebaceous glands in the dermis secrete an oil called sebum that is released onto the skin surface through hair follicles. This sebum is an endogenous mediator, providing an additional layer of defense by helping seal off the pore of the hair follicle, preventing bacteria on the skin’s surface from invading sweat glands and surrounding tissue ( Figure 17.8 ). Certain members of the microbiome, such as the bacterium Propionibacterium acnes and the fungus Malassezia , among others, can use lipase enzymes to degrade sebum, using it as a food source. This produces oleic acid , which creates a mildly acidic environment on the surface of the skin that is inhospitable to many pathogenic microbes. Oleic acid is an example of an exogenously produced mediator because it is produced by resident microbes and not directly by body cells. Environmental factors that affect the microbiota of the skin can have a direct impact on the production of chemical mediators. Low humidity or decreased sebum production, for example, could make the skin less habitable for microbes that produce oleic acid, thus making the skin more susceptible to pathogens normally inhibited by the skin’s low pH. Many skin moisturizers are formulated to counter such effects by restoring moisture and essential oils to the skin. The digestive tract also produces a large number of chemical mediators that inhibit or kill microbes. In the oral cavity, saliva contains mediators such as lactoperoxidase enzymes, and mucus secreted by the esophagus contains the antibacterial enzyme lysozyme . In the stomach, highly acidic gastric fluid kills most microbes. In the lower digestive tract, the intestines have pancreatic and intestinal enzymes, antibacterial peptides (cryptins), bile produced from the liver, and specialized Paneth cells that produce lysozyme. Together, these mediators are able to eliminate most pathogens that manage to survive the acidic environment of the stomach. In the urinary tract, urine flushes microbes out of the body during urination. Furthermore, the slight acidity of urine (the average pH is about 6) inhibits the growth of many microbes and potential pathogens in the urinary tract. The female reproductive system employs lactate, an exogenously produced chemical mediator, to inhibit microbial growth. The cells and tissue layers composing the vagina produce glycogen, a branched and more complex polymer of glucose. Lactobacilli in the area ferment glycogen to produce lactate, lowering the pH in the vagina and inhibiting transient microbiota, opportunistic pathogens like Candida (a yeast associated with vaginal infections), and other pathogens responsible for sexually transmitted diseases. In the eyes, tears contain the chemical mediators lysozyme and lactoferrin , both of which are capable of eliminating microbes that have found their way to the surface of the eyes. Lysozyme cleaves the bond between NAG and NAM in peptidoglycan, a component of the cell wall in bacteria. It is more effective against gram-positive bacteria, which lack the protective outer membrane associated with gram-negative bacteria. Lactoferrin inhibits microbial growth by chemically binding and sequestering iron. This effectually starves many microbes that require iron for growth. In the ears, cerumen (earwax) exhibits antimicrobial properties due to the presence of fatty acids, which lower the pH to between 3 and 5. The respiratory tract uses various chemical mediators in the nasal passages, trachea, and lungs. The mucus produced in the nasal passages contains a mix of antimicrobial molecules similar to those found in tears and saliva (e.g., lysozyme, lactoferrin, lactoperoxidase). Secretions in the trachea and lungs also contain lysozyme and lactoferrin, as well as a diverse group of additional chemical mediators, such as the lipoprotein complex called surfactant , which has antibacterial properties. Check Your Understanding Explain the difference between endogenous and exogenous mediators Describe how pH affects antimicrobial defenses Antimicrobial Peptides The antimicrobial peptides (AMPs) are a special class of nonspecific cell-derived mediators with broad-spectrum antimicrobial properties. Some AMPs are produced routinely by the body, whereas others are primarily produced (or produced in greater quantities) in response to the presence of an invading pathogen. Research has begun exploring how AMPs can be used in the diagnosis and treatment of disease. AMPs may induce cell damage in microorganisms in a variety of ways, including by inflicting damage to membranes, destroying DNA and RNA, or interfering with cell-wall synthesis. Depending on the specific antimicrobial mechanism, a particular AMP may inhibit only certain groups of microbes (e.g., gram-positive or gram-negative bacteria) or it may be more broadly effective against bacteria, fungi, protozoa, and viruses. Many AMPs are found on the skin, but they can also be found in other regions of the body. A family of AMPs called defensins can be produced by epithelial cells throughout the body as well as by cellular defenses such as macrophages and neutrophils (see Cellular Defenses ). Defensins may be secreted or act inside host cells; they combat microorganisms by damaging their plasma membranes. AMPs called bacteriocins are produced exogenously by certain members of the resident microbiota within the gastrointestinal tract. The genes coding for these types of AMPs are often carried on plasmids and can be passed between different species within the resident microbiota through lateral or horizontal gene transfer. There are numerous other AMPs throughout the body. The characteristics of a few of the more significant AMPs are summarized in Table 17.3 . Characteristics of Selected Antimicrobial Peptides (AMPs) AMP Secreted by Body site Pathogens inhibited Mode of action Bacteriocins Resident microbiota Gastrointestinal tract Bacteria Disrupt membrane Cathelicidin Epithelial cells, macrophages, and other cell types Skin Bacteria and fungi Disrupts membrane Defensins Epithelial cells, macrophages, neutrophils Throughout the body Fungi, bacteria, and many viruses Disrupt membrane Dermicidin Sweat glands Skin Bacteria and fungi Disrupts membrane integrity and ion channels Histatins Salivary glands Oral cavity Fungi Disrupt intracellular function Table 17.3 Check Your Understanding Why are antimicrobial peptides (AMPs) considered nonspecific defenses? Plasma Protein Mediators Many nonspecific innate immune factors are found in plasma , the fluid portion of blood. Plasma contains electrolytes, sugars, lipids, and proteins, each of which helps to maintain homeostasis (i.e., stable internal body functioning), and contains the proteins involved in the clotting of blood. Additional proteins found in blood plasma, such as acute-phase proteins, complement proteins, and cytokines, are involved in the nonspecific innate immune response. Micro Connections Plasma versus Serum There are two terms for the fluid portion of blood: plasma and serum. How do they differ if they are both fluid and lack cells? The fluid portion of blood left over after coagulation (blood cell clotting) has taken place is serum . Although molecules such as many vitamins, electrolytes, certain sugars, complement proteins, and antibodies are still present in serum, clotting factors are largely depleted. Plasma, conversely, still contains all the clotting elements. To obtain plasma from blood, an anticoagulant must be used to prevent clotting. Examples of anticoagulants include heparin and ethylene diamine tetraacetic acid (EDTA). Because clotting is inhibited, once obtained, the sample must be gently spun down in a centrifuge. The heavier, denser blood cells form a pellet at the bottom of a centrifuge tube, while the fluid plasma portion, which is lighter and less dense, remains above the cell pellet. Acute-Phase Proteins The acute-phase proteins are another class of antimicrobial mediators. Acute-phase proteins are primarily produced in the liver and secreted into the blood in response to inflammatory molecules from the immune system. Examples of acute-phase proteins include C-reactive protein , serum amyloid A , ferritin , transferrin , fibrinogen , and mannose-binding lectin . Each of these proteins has a different chemical structure and inhibits or destroys microbes in some way ( Table 17.4 ). Some Acute-Phase Proteins and Their Functions C-reactive protein Coats bacteria (opsonization), preparing them for ingestion by phagocytes Serum amyloid A Ferritin Bind and sequester iron, thereby inhibiting the growth of pathogens Transferrin Fibrinogen Involved in formation of blood clots that trap bacterial pathogens Mannose-binding lectin Activates complement cascade Table 17.4 The Complement System The complement system is a group of plasma protein mediators that can act as an innate nonspecific defense while also serving to connect innate and adaptive immunity (discussed in the next chapter). The complement system is composed of more than 30 proteins (including C1 through C9) that normally circulate as precursor proteins in blood. These precursor proteins become activated when stimulated or triggered by a variety of factors, including the presence of microorganisms. Complement proteins are considered part of innate nonspecific immunity because they are always present in the blood and tissue fluids, allowing them to be activated quickly. Also, when activated through the alternative pathway (described later in this section), complement proteins target pathogens in a nonspecific manner. The process by which circulating complement precursors become functional is called complement activation . This process is a cascade that can be triggered by one of three different mechanisms, known as the alternative, classical, and lectin pathways. The alternative pathway is initiated by the spontaneous activation of the complement protein C3. The hydrolysis of C3 produces two products, C3a and C3b. When no invader microbes are present, C3b is very quickly degraded in a hydrolysis reaction using the water in the blood. However, if invading microbes are present, C3b attaches to the surface of these microbes. Once attached, C3b will recruit other complement proteins in a cascade ( Figure 17.9 ). The classical pathway provides a more efficient mechanism of activating the complement cascade, but it depends upon the production of antibodies by the specific adaptive immune defenses. To initiate the classical pathway, a specific antibody must first bind to the pathogen to form an antibody-antigen complex. This activates the first protein in the complement cascade, the C1 complex. The C1 complex is a multipart protein complex, and each component participates in the full activation of the overall complex. Following recruitment and activation of the C1 complex, the remaining classical pathway complement proteins are recruited and activated in a cascading sequence ( Figure 17.9 ). The lectin activation pathway is similar to the classical pathway, but it is triggered by the binding of mannose-binding lectin, an acute-phase protein, to carbohydrates on the microbial surface. Like other acute-phase proteins, lectins are produced by liver cells and are commonly upregulated in response to inflammatory signals received by the body during an infection ( Figure 17.9 ). Although each complement activation pathway is initiated in a different way, they all provide the same protective outcomes: opsonization, inflammation, chemotaxis , and cytolysis. The term opsonization refers to the coating of a pathogen by a chemical substance (called an opsonin ) that allows phagocytic cells to recognize, engulf, and destroy it more easily. Opsonins from the complement cascade include C1q, C3b, and C4b. Additional important opsonins include mannose-binding proteins and antibodies. The complement fragments C3a and C5a are well-characterized anaphylatoxins with potent proinflammatory functions. Anaphylatoxins activate mast cells, causing degranulation and the release of inflammatory chemical signals, including mediators that cause vasodilation and increased vascular permeability. C5a is also one of the most potent chemoattractants for neutrophils and other white blood cells, cellular defenses that will be discussed in the next section. The complement proteins C6, C7, C8, and C9 assemble into a membrane attack complex (MAC) , which allows C9 to polymerize into pores in the membranes of gram-negative bacteria. These pores allow water, ions, and other molecules to move freely in and out of the targeted cells, eventually leading to cell lysis and death of the pathogen ( Figure 17.9 ). However, the MAC is only effective against gram-negative bacteria; it cannot penetrate the thick layer of peptidoglycan associated with cell walls of gram-positive bacteria. Since the MAC does not pose a lethal threat to gram-positive bacterial pathogens, complement-mediated opsonization is more important for their clearance. Cytokines Cytokines are soluble proteins that act as communication signals between cells. In a nonspecific innate immune response, various cytokines may be released to stimulate production of chemical mediators or other cell functions, such as cell proliferation, cell differentiation, inhibition of cell division, apoptosis, and chemotaxis. When a cytokine binds to its target receptor, the effect can vary widely depending on the type of cytokine and the type of cell or receptor to which it has bound. The function of a particular cytokine can be described as autocrine, paracrine, or endocrine ( Figure 17.10 ). In autocrine function , the same cell that releases the cytokine is the recipient of the signal; in other words, autocrine function is a form of self-stimulation by a cell. In contrast, paracrine function involves the release of cytokines from one cell to other nearby cells, stimulating some response from the recipient cells. Last, endocrine function occurs when cells release cytokines into the bloodstream to be carried to target cells much farther away. Three important classes of cytokines are the interleukins, chemokines, and interferons. The interleukins were originally thought to be produced only by leukocytes (white blood cells) and to only stimulate leukocytes, thus the reasons for their name. Although interleukins are involved in modulating almost every function of the immune system, their role in the body is not restricted to immunity. Interleukins are also produced by and stimulate a variety of cells unrelated to immune defenses. The chemokines are chemotactic factors that recruit leukocytes to sites of infection, tissue damage, and inflammation. In contrast to more general chemotactic factors, like complement factor C5a, chemokines are very specific in the subsets of leukocytes they recruit. Interferons are a diverse group of immune signaling molecules and are especially important in our defense against viruses. Type I interferons (interferon-α and interferon-β) are produced and released by cells infected with virus. These interferons stimulate nearby cells to stop production of mRNA, destroy RNA already produced, and reduce protein synthesis. These cellular changes inhibit viral replication and production of mature virus, slowing the spread of the virus. Type I interferons also stimulate various immune cells involved in viral clearance to more aggressively attack virus-infected cells. Type II interferon (interferon-γ) is an important activator of immune cells ( Figure 17.11 ). Inflammation-Eliciting Mediators Many of the chemical mediators discussed in this section contribute in some way to inflammation and fever, which are nonspecific immune responses discussed in more detail in Inflammation and Fever . Cytokines stimulate the production of acute-phase proteins such as C-reactive protein and mannose-binding lectin in the liver. These acute-phase proteins act as opsonins , activating complement cascades through the lectin pathway. Some cytokines also bind mast cells and basophils , inducing them to release histamine , a proinflammatory compound. Histamine receptors are found on a variety of cells and mediate proinflammatory events, such as bronchoconstriction (tightening of the airways) and smooth muscle contraction. In addition to histamine, mast cells may release other chemical mediators, such as leukotrienes . Leukotrienes are lipid-based proinflammatory mediators that are produced from the metabolism of arachidonic acid in the cell membrane of leukocytes and tissue cells. Compared with the proinflammatory effects of histamine, those of leukotrienes are more potent and longer lasting. Together, these chemical mediators can induce coughing, vomiting, and diarrhea, which serve to expel pathogens from the body. Certain cytokines also stimulate the production of prostaglandins , chemical mediators that promote the inflammatory effects of kinins and histamines. Prostaglandins can also help to set the body temperature higher, leading to fever , which promotes the activities of white blood cells and slightly inhibits the growth of pathogenic microbes (see Inflammation and Fever ). Another inflammatory mediator, bradykinin , contributes to edema , which occurs when fluids and leukocytes leak out of the bloodstream and into tissues. It binds to receptors on cells in the capillary walls, causing the capillaries to dilate and become more permeable to fluids. Check Your Understanding What do the three complement activation pathways have in common? Explain autocrine, paracrine, and endocrine signals. Name two important inflammation-eliciting mediators. Clinical Focus Part 2 To relieve the constriction of her airways, Angela is immediately treated with antihistamines and administered corticosteroids through an inhaler, and then monitored for a period of time. Though her condition does not worsen, the drugs do not seem to be alleviating her condition. She is admitted to the hospital for further observation, testing, and treatment. Following admission, a clinician conducts allergy testing to try to determine if something in her environment might be triggering an allergic inflammatory response. A doctor orders blood analysis to check for levels of particular cytokines. A sputum sample is also taken and sent to the lab for microbial staining, culturing, and identification of pathogens that could be causing an infection. Which aspects of the innate immune system could be contributing to Angela’s airway constriction? Why was Angela treated with antihistamines? Why would the doctor be interested in levels of cytokines in Angela’s blood? Jump to the next Clinical Focus box. Go back to the previous Clinical Focus box. Table 17.5 provides a summary of the chemical defenses discussed in this section. Chemical Defenses of Nonspecific Innate Immunity Defense Examples Function Chemicals and enzymes in body fluids Sebum from sebaceous glands Provides oil barrier protecting hair follicle pores from pathogens Oleic acid from sebum and skin microbiota Lowers pH to inhibit pathogens Lysozyme in secretions Kills bacteria by attacking cell wall Acid in stomach, urine, and vagina Inhibits or kills bacteria Digestive enzymes and bile Kill bacteria Lactoferrin and transferrin Bind and sequester iron, inhibiting bacterial growth Surfactant in lungs Kills bacteria Antimicrobial peptides Defensins, bacteriocins, dermicidin, cathelicidin, histatins, Kill bacteria by attacking membranes or interfering with cell functions Plasma protein mediators Acute-phase proteins (C-reactive protein, serum amyloid A, ferritin, fibrinogen, transferrin, and mannose-binding lectin) Inhibit the growth of bacteria and assist in the trapping and killing of bacteria Complements C3b and C4b Opsonization of pathogens to aid phagocytosis Complement C5a Chemoattractant for phagocytes Complements C3a and C5a Proinflammatory anaphylatoxins Cytokines Interleukins Stimulate and modulate most functions of immune system Chemokines Recruit white blood cells to infected area Interferons Alert cells to viral infection, induce apoptosis of virus-infected cells, induce antiviral defenses in infected and nearby uninfected cells, stimulate immune cells to attack virus-infected cells Inflammation-eliciting mediators Histamine Promotes vasodilation, bronchoconstriction, smooth muscle contraction, increased secretion and mucus production Leukotrienes Promote inflammation; stronger and longer lasting than histamine Prostaglandins Promote inflammation and fever Bradykinin Increases vasodilation and vascular permeability, leading to edema Table 17.5 17.3 Cellular Defenses Learning Objectives Identify and describe the components of blood Explain the process by which the formed elements of blood are formed (hematopoiesis) Describe the characteristics of formed elements found in peripheral blood, as well as their respective functions within the innate immune system In the previous section, we discussed some of the chemical mediators found in plasma, the fluid portion of blood. The nonfluid portion of blood consists of various types of formed elements , so called because they are all formed from the same stem cells found in bone marrow. The three major categories of formed elements are: red blood cells (RBCs), also called erythrocyte s ; platelets , also called thrombocytes ; and white blood cells (WBCs), also called leukocytes . Red blood cells are primarily responsible for carrying oxygen to tissues. Platelets are cellular fragments that participate in blood clot formation and tissue repair. Several different types of WBCs participate in various nonspecific mechanisms of innate and adaptive immunity. In this section, we will focus primarily on the innate mechanisms of various types of WBCs. Hematopoiesis All of the formed elements of blood are derived from pluripotent hematopoietic stem cells (HSCs) in the bone marrow. As the HSCs make copies of themselves in the bone marrow, individual cells receive different cues from the body that control how they develop and mature. As a result, the HSCs differentiate into different types of blood cells that, once mature, circulate in peripheral blood. This process of differentiation, called hematopoiesis , is shown in more detail in Figure 17.12 . In terms of sheer numbers, the vast majority of HSCs become erythrocytes. Much smaller numbers become leukocytes and platelets. Leukocytes can be further subdivided into granulocytes , which are characterized by numerous granules visible in the cytoplasm, and agranulocytes , which lack granules. Figure 17.13 provides an overview of the various types of formed elements, including their relative numbers, primary function, and lifespans. Granulocytes The various types of granulocytes can be distinguished from one another in a blood smear by the appearance of their nuclei and the contents of their granules, which confer different traits, functions, and staining properties. The neutrophils , also called polymorphonuclear neutrophils (PMNs) , have a nucleus with three to five lobes and small, numerous, lilac-colored granules. Each lobe of the nucleus is connected by a thin strand of material to the other lobes. The eosinophils have fewer lobes in the nucleus (typically 2–3) and larger granules that stain reddish-orange. The basophils have a two-lobed nucleus and large granules that stain dark blue or purple ( Figure 17.14 ). Neutrophils (PMNs) Neutrophils (PMNs) are frequently involved in the elimination and destruction of extracellular bacteria. They are capable of migrating through the walls of blood vessels to areas of bacterial infection and tissue damage, where they seek out and kill infectious bacteria. PMN granules contain a variety of defensins and hydrolytic enzymes that help them destroy bacteria through phagocytosis (described in more detail in Pathogen Recognition and Phagocytosis ) In addition, when many neutrophils are brought into an infected area, they can be stimulated to release toxic molecules into the surrounding tissue to better clear infectious agents. This is called degranulation . Another mechanism used by neutrophils is neutrophil extracellular traps (NETs) , which are extruded meshes of chromatin that are closely associated with antimicrobial granule proteins and components. Chromatin is DNA with associated proteins (usually histone proteins, around which DNA wraps for organization and packing within a cell). By creating and releasing a mesh or lattice-like structure of chromatin that is coupled with antimicrobial proteins, the neutrophils can mount a highly concentrated and efficient attack against nearby pathogens. Proteins frequently associated with NETs include lactoferrin, gelatinase, cathepsin G, and myeloperoxidase. Each has a different means of promoting antimicrobial activity, helping neutrophils eliminate pathogens. The toxic proteins in NETs may kill some of the body’s own cells along with invading pathogens. However, this collateral damage can be repaired after the danger of the infection has been eliminated. As neutrophils fight an infection, a visible accumulation of leukocytes, cellular debris, and bacteria at the site of infection can be observed. This buildup is what we call pus (also known as purulent or suppurative discharge or drainage). The presence of pus is a sign that the immune defenses have been activated against an infection; historically, some physicians believed that inducing pus formation could actually promote the healing of wounds. The practice of promoting “laudable pus” (by, for instance, wrapping a wound in greasy wool soaked in wine) dates back to the ancient physician Galen in the 2nd century AD, and was practiced in variant forms until the 17th century (though it was not universally accepted). Today, this method is no longer practiced because we now know that it is not effective. Although a small amount of pus formation can indicate a strong immune response, artificially inducing pus formation does not promote recovery. Eosinophils Eosinophils are granulocytes that protect against protozoa and helminths; they also play a role in allergic reactions. The granules of eosinophils , which readily absorb the acidic reddish dye eosin, contain histamine, degradative enzymes, and a compound known as major basic protein (MBP) ( Figure 17.14 ). MBP binds to the surface carbohydrates of parasites, and this binding is associated with disruption of the cell membrane and membrane permeability. Basophils Basophils have cytoplasmic granules of varied size and are named for their granules’ ability to absorb the basic dye methylene blue ( Figure 17.14 ). Their stimulation and degranulation can result from multiple triggering events. Activated complement fragments C3a and C5a, produced in the activation cascades of complement proteins, act as anaphylatoxins by inducing degranulation of basophils and inflammatory responses. This cell type is important in allergic reactions and other responses that involve inflammation. One of the most abundant components of basophil granules is histamine , which is released along with other chemical factors when the basophil is stimulated. These chemicals can be chemotactic and can help to open the gaps between cells in the blood vessels. Other mechanisms for basophil triggering require the assistance of antibodies, as discussed in B Lymphocytes and Humoral Immunity . Mast Cells Hematopoiesis also gives rise to mast cells , which appear to be derived from the same common myeloid progenitor cell as neutrophils, eosinophils, and basophils. Functionally, mast cells are very similar to basophils, containing many of the same components in their granules (e.g., histamine ) and playing a similar role in allergic responses and other inflammatory reactions. However, unlike basophils, mast cells leave the circulating blood and are most frequently found residing in tissues. They are often associated with blood vessels and nerves or found close to surfaces that interface with the external environment, such as the skin and mucous membranes in various regions of the body ( Figure 17.15 ). Check Your Understanding Describe the granules and nuclei of neutrophils, eosinophils, basophils, and mast cells. Name three antimicrobial mechanisms of neutrophils Clinical Focus Part 3 Angela’s tests come back negative for all common allergens, and her sputum samples contain no abnormal presence of pathogenic microbes or elevated levels of members of the normal respiratory microbiota. She does, however, have elevated levels of inflammatory cytokines in her blood. The swelling of her airway has still not responded to treatment with antihistamines or corticosteroids. Additional blood work shows that Angela has a mildly elevated white blood cell count but normal antibody levels. Also, she has a lower-than-normal level of the complement protein C4. What does this new information reveal about the cause of Angela’s constricted airways? What are some possible conditions that could lead to low levels of complement proteins? Jump to the next Clinical Focus box. Go back to the previous Clinical Focus box. Agranulocytes As their name suggests, agranulocytes lack visible granules in the cytoplasm. Agranulocytes can be categorized as lymphocytes or monocytes ( Figure 17.13 ). Among the lymphocytes are natural killer cells, which play an important role in nonspecific innate immune defenses. Lymphocytes also include the B cells and T cells, which are discussed in the next chapter because they are central players in the specific adaptive immune defenses. The monocytes differentiate into macrophages and dendritic cells , which are collectively referred to as the mononuclear phagocyte system. Natural Killer Cells Most lymphocytes are primarily involved in the specific adaptive immune response, and thus will be discussed in the following chapter. An exception is the natural killer cells (NK cells) ; these mononuclear lymphocytes use nonspecific mechanisms to recognize and destroy cells that are abnormal in some way. Cancer cells and cells infected with viruses are two examples of cellular abnormalities that are targeted by NK cells. Recognition of such cells involves a complex process of identifying inhibitory and activating molecular markers on the surface of the target cell. Molecular markers that make up the major histocompatibility complex (MHC) are expressed by healthy cells as an indication of “self.” This will be covered in more detail in next chapter. NK cells are able to recognize normal MHC markers on the surface of healthy cells, and these MHC markers serve as an inhibitory signal preventing NK cell activation. However, cancer cells and virus-infected cells actively diminish or eliminate expression of MHC markers on their surface. When these MHC markers are diminished or absent, the NK cell interprets this as an abnormality and a cell in distress. This is one part of the NK cell activation process ( Figure 17.16 ). NK cells are also activated by binding to activating molecular molecules on the target cell. These activating molecular molecules include “altered self” or “nonself” molecules. When a NK cell recognizes a decrease in inhibitory normal MHC molecules and an increase in activating molecules on the surface of a cell, the NK cell will be activated to eliminate the cell in distress. Once a cell has been recognized as a target, the NK cell can use several different mechanisms to kill its target. For example, it may express cytotoxic membrane proteins and cytokines that stimulate the target cell to undergo apoptosis , or controlled cell suicide. NK cells may also use perforin-mediated cytotoxicity to induce apoptosis in target cells. This mechanism relies on two toxins released from granules in the cytoplasm of the NK cell: perforin , a protein that creates pores in the target cell, and granzymes , proteases that enter through the pores into the target cell’s cytoplasm, where they trigger a cascade of protein activation that leads to apoptosis. The NK cell binds to the abnormal target cell, releases its destructive payload, and detaches from the target cell. While the target cell undergoes apoptosis, the NK cell synthesizes more perforin and proteases to use on its next target. NK cells contain these toxic compounds in granules in their cytoplasm. When stained, the granules are azurophilic and can be visualized under a light microscope ( Figure 17.17 ). Even though they have granules, NK cells are not considered granulocytes because their granules are far less numerous than those found in true granulocytes. Furthermore, NK cells have a different lineage than granulocytes, arising from lymphoid rather than myeloid stem cells ( Figure 17.12 ). Monocytes The largest of the white blood cells, monocytes have a nucleus that lacks lobes, and they also lack granules in the cytoplasm ( Figure 17.18 ). Nevertheless, they are effective phagocytes, engulfing pathogens and apoptotic cells to help fight infection. When monocytes leave the bloodstream and enter a specific body tissue, they differentiate into tissue-specific phagocytes called macrophages and dendritic cells . They are particularly important residents of lymphoid tissue, as well as nonlymphoid sites and organs. Macrophages and dendritic cells can reside in body tissues for significant lengths of time. Macrophages in specific body tissues develop characteristics suited to the particular tissue. Not only do they provide immune protection for the tissue in which they reside but they also support normal function of their neighboring tissue cells through the production of cytokines. Macrophages are given tissue-specific names, and a few examples of tissue-specific macrophages are listed in Table 17.6 . Dendritic cells are important sentinels residing in the skin and mucous membranes, which are portals of entry for many pathogens. Monocytes, macrophages, and dendritic cells are all highly phagocytic and important promoters of the immune response through their production and release of cytokines. These cells provide an essential bridge between innate and adaptive immune responses, as discussed in the next section as well as the next chapter. Macrophages Found in Various Body Tissues Tissue Macrophage Brain and central nervous system Microglial cells Liver Kupffer cells Lungs Alveolar macrophages (dust cells) Peritoneal cavity Peritoneal macrophages Table 17.6 Check Your Understanding Describe the signals that activate natural killer cells. What is the difference between monocytes and macrophages? 17.4 Pathogen Recognition and Phagocytosis Learning Objectives Explain how leukocytes migrate from peripheral blood into infected tissues Explain the mechanisms by which leukocytes recognize pathogens Explain the process of phagocytosis and the mechanisms by which phagocytes destroy and degrade pathogens Several of the cell types discussed in the previous section can be described as phagocytes—cells whose main function is to seek, ingest, and kill pathogens. This process, called phagocytosis , was first observed in starfish in the 1880s by Nobel Prize-winning zoologist Ilya Metchnikoff (1845–1916), who made the connection to white blood cells (WBCs) in humans and other animals. At the time, Pasteur and other scientists believed that WBCs were spreading pathogens rather than killing them (which is true for some diseases, such as tuberculosis). But in most cases, phagocytes provide a strong, swift, and effective defense against a broad range of microbes, making them a critical component of innate nonspecific immunity. This section will focus on the mechanisms by which phagocytes are able to seek, recognize, and destroy pathogens. Extravasation (Diapedesis) of Leukocytes Some phagocytes are leukocytes (WBCs) that normally circulate in the bloodstream. To reach pathogens located in infected tissue, leukocytes must pass through the walls of small capillary blood vessels within tissues. This process, called extravasation , or diapedesis , is initiated by complement factor C5a, as well as cytokines released into the immediate vicinity by resident macrophages and tissue cells responding to the presence of the infectious agent ( Figure 17.19 ). Similar to C5a, many of these cytokines are proinflammatory and chemotactic, and they bind to cells of small capillary blood vessels, initiating a response in the endothelial cells lining the inside of the blood vessel walls. This response involves the upregulation and expression of various cellular adhesion molecules and receptors. Leukocytes passing through will stick slightly to the adhesion molecules, slowing down and rolling along the blood vessel walls near the infected area. When they reach a cellular junction, they will bind to even more of these adhesion molecules, flattening out and squeezing through the cellular junction in a process known as transendothelial migration . This mechanism of “rolling adhesion” allows leukocytes to exit the bloodstream and enter the infected areas, where they can begin phagocytosing the invading pathogens. Note that extravasation does not occur in arteries or veins. These blood vessels are surrounded by thicker, multilayer protective walls, in contrast to the thin single-cell-layer walls of capillaries. Furthermore, the blood flow in arteries is too turbulent to allow for rolling adhesion. Also, some leukocytes tend to respond to an infection more quickly than others. The first to arrive typically are neutrophils , often within hours of a bacterial infection. By contract, monocytes may take several days to leave the bloodstream and differentiate into macrophages . Link to Learning Watch the following videos on leukocyte extravasation and leukocyte rolling to learn more. Check Your Understanding Explain the role of adhesion molecules in the process of extravasation. Pathogen Recognition As described in the previous section, opsonization of pathogens by antibody; complement factors C1q, C3b, and C4b; and lectins can assist phagocytic cells in recognition of pathogens and attachment to initiate phagocytosis. However, not all pathogen recognition is opsonin dependent. Phagocytes can also recognize molecular structures that are common to many groups of pathogenic microbes. Such structures are called pathogen-associated molecular patterns (PAMPs) . Common PAMPs include the following: peptidoglycan , found in bacterial cell walls; flagellin , a protein found in bacterial flagella; lipopolysaccharide (LPS) from the outer membrane of gram-negative bacteria; lipopeptides , molecules expressed by most bacteria; and nucleic acids such as viral DNA or RNA. Like numerous other PAMPs, these substances are integral to the structure of broad classes of microbes. The structures that allow phagocytic cells to detect PAMPs are called pattern recognition receptors (PRRs) . One group of PRRs is the toll-like receptors (TLRs) , which bind to various PAMPs and communicate with the nucleus of the phagocyte to elicit a response. Many TLRs (and other PRRs) are located on the surface of a phagocyte, but some can also be found embedded in the membranes of interior compartments and organelles ( Figure 17.20 ). These interior PRRs can be useful for the binding and recognition of intracellular pathogens that may have gained access to the inside of the cell before phagocytosis could take place. Viral nucleic acids, for example, might encounter an interior PRR, triggering production of the antiviral cytokine interferon. In addition to providing the first step of pathogen recognition, the interaction between PAMPs and PRRs on macrophages provides an intracellular signal that activates the phagocyte, causing it to transition from a dormant state of readiness and slow proliferation to a state of hyperactivity, proliferation, production/secretion of cytokines, and enhanced intracellular killing. PRRs on macrophages also respond to chemical distress signals from damaged or stressed cells. This allows macrophages to extend their responses beyond protection from infectious diseases to a broader role in the inflammatory response initiated from injuries or other diseases. Check Your Understanding Name four pathogen-associated molecular patterns (PAMPs). Describe the process of phagocyte activation. Pathogen Degradation Once pathogen recognition and attachment occurs, the pathogen is engulfed in a vesicle and brought into the internal compartment of the phagocyte in a process called phagocytosis ( Figure 17.21 ). PRRs can aid in phagocytosis by first binding to the pathogen’s surface, but phagocytes are also capable of engulfing nearby items even if they are not bound to specific receptors. To engulf the pathogen, the phagocyte forms a pseudopod that wraps around the pathogen and then pinches it off into a membrane vesicle called a phagosome . Acidification of the phagosome (pH decreases to the range of 4–5) provides an important early antibacterial mechanism. The phagosome containing the pathogen fuses with one or more lysosomes, forming a phagolysosome . Formation of the phagolysosome enhances the acidification, which is essential for activation of pH-dependent digestive lysosomal enzymes and production of hydrogen peroxide and toxic reactive oxygen species. Lysosomal enzymes such as lysozyme , phospholipase, and proteases digest the pathogen. Other enzymes are involved in a respiratory burst. During the respiratory burst , phagocytes will increase their uptake and consumption of oxygen, but not for energy production. The increased oxygen consumption is focused on the production of superoxide anion, hydrogen peroxide, hydroxyl radicals, and other reactive oxygen species that are antibacterial. In addition to the reactive oxygen species produced by the respiratory burst, reactive nitrogen compounds with cytotoxic (cell-killing) potential can also form. For example, nitric oxide can react with superoxide to form peroxynitrite, a highly reactive nitrogen compound with degrading capabilities similar to those of the reactive oxygen species. Some phagocytes even contain an internal storehouse of microbicidal defensin proteins (e.g., neutrophil granules). These destructive forces can be released into the area around the cell to degrade microbes externally. Neutrophils, especially, can be quite efficient at this secondary antimicrobial mechanism. Once degradation is complete, leftover waste products are excreted from the cell in an exocytic vesicle. However, it is important to note that not all remains of the pathogen are excreted as waste. Macrophages and dendritic cells are also antigen-presenting cells involved in the specific adaptive immune response. These cells further process the remains of the degraded pathogen and present key antigens (specific pathogen proteins) on their cellular surface. This is an important step for stimulation of some adaptive immune responses, as will be discussed in more detail in the next chapter. Link to Learning Visit this link to view a phagocyte chasing and engulfing a pathogen. Check Your Understanding What is the difference between a phagosome and a lysosome? Micro Connections When Phagocytosis Fails Although phagocytosis successfully destroys many pathogens, some are able to survive and even exploit this defense mechanism to multiply in the body and cause widespread infection. Protozoans of the genus Leishmania are one example. These obligate intracellular parasites are flagellates transmitted to humans by the bite of a sand fly. Infections cause serious and sometimes disfiguring sores and ulcers in the skin and other tissues ( Figure 17.22 ). Worldwide, an estimated 1.3 million people are newly infected with leishmaniasis annually. 1 1 World Health Organization. “Leishmaniasis.” 2016. http://www.who.int/mediacentre/factsheets/fs375/en/. Salivary peptides from the sand fly activate host macrophages at the site of their bite. The classic or alternate pathway for complement activation ensues with C3b opsonization of the parasite. Leishmania cells are phagocytosed, lose their flagella, and multiply in a form known as an amastigote (Leishman-Donovan body) within the phagolysosome. Although many other pathogens are destroyed in the phagolysosome, survival of the Leishmania amastigotes is maintained by the presence of surface lipophosphoglycan and acid phosphatase. These substances inhibit the macrophage respiratory burst and lysosomal enzymes. The parasite then multiplies inside the cell and lyses the infected macrophage, releasing the amastigotes to infect other macrophages within the same host. Should another sand fly bite an infected person, it might ingest amastigotes and then transmit them to another individual through another bite. There are several different forms of leishmaniasis. The most common is a localized cutaneous form of the illness caused by L. tropica , which typically resolves spontaneously over time but with some significant lymphocyte infiltration and permanent scarring. A mucocutaneous form of the disease, caused by L. viannia brasilienfsis , produces lesions in the tissue of the nose and mouth and can be life threatening. A visceral form of the illness can be caused by several of the different Leishmania species. It affects various organ systems and causes abnormal enlargement of the liver and spleen. Irregular fevers, anemia, liver dysfunction, and weight loss are all signs and symptoms of visceral leishmaniasis. If left untreated, it is typically fatal. 17.5 Inflammation and Fever Learning Objectives Identify the signs of inflammation and fever and explain why they occur Explain the advantages and risks posed by inflammatory responses The inflammatory response, or inflammation , is triggered by a cascade of chemical mediators and cellular responses that may occur when cells are damaged and stressed or when pathogens successfully breach the physical barriers of the innate immune system. Although inflammation is typically associated with negative consequences of injury or disease, it is a necessary process insofar as it allows for recruitment of the cellular defenses needed to eliminate pathogens, remove damaged and dead cells, and initiate repair mechanisms. Excessive inflammation, however, can result in local tissue damage and, in severe cases, may even become deadly. Acute Inflammation An early, if not immediate, response to tissue injury is acute inflammation . Immediately following an injury, vasoconstriction of blood vessels will occur to minimize blood loss. The amount of vasoconstriction is related to the amount of vascular injury, but it is usually brief. Vasoconstriction is followed by vasodilation and increased vascular permeability, as a direct result of the release of histamine from resident mast cells. Increased blood flow and vascular permeability can dilute toxins and bacterial products at the site of injury or infection. They also contribute to the five observable signs associated with the inflammatory response: erythema (redness), edema (swelling), heat, pain, and altered function. Vasodilation and increased vascular permeability are also associated with an influx of phagocytes at the site of injury and/or infection. This can enhance the inflammatory response because phagocytes may release proinflammatory chemicals when they are activated by cellular distress signals released from damaged cells, by PAMPs , or by opsonins on the surface of pathogens. Activation of the complement system can further enhance the inflammatory response through the production of the anaphylatoxin C5a. Figure 17.23 illustrates a typical case of acute inflammation at the site of a skin wound. During the period of inflammation, the release of bradykinin causes capillaries to remain dilated, flooding tissues with fluids and leading to edema. Increasing numbers of neutrophils are recruited to the area to fight pathogens. As the fight rages on, pus forms from the accumulation of neutrophils, dead cells, tissue fluids, and lymph. Typically, after a few days, macrophages will help to clear out this pus. Eventually, tissue repair can begin in the wounded area. Chronic Inflammation When acute inflammation is unable to clear an infectious pathogen, chronic inflammation may occur. This often results in an ongoing (and sometimes futile) lower-level battle between the host organism and the pathogen. The wounded area may heal at a superficial level, but pathogens may still be present in deeper tissues, stimulating ongoing inflammation. Additionally, chronic inflammation may be involved in the progression of degenerative neurological diseases such as Alzheimer’s and Parkinson’s, heart disease, and metastatic cancer. Chronic inflammation may lead to the formation of granuloma s , pockets of infected tissue walled off and surrounded by WBCs. Macrophages and other phagocytes wage an unsuccessful battle to eliminate the pathogens and dead cellular materials within a granuloma. One example of a disease that produces chronic inflammation is tuberculosis , which results in the formation of granulomas in lung tissues. A tubercular granuloma is called a tubercle ( Figure 17.24 ). Tuberculosis will be covered in more detail in Bacterial Infections of the Respiratory Tract . Chronic inflammation is not just associated with bacterial infections. Chronic inflammation can be an important cause of tissue damage from viral infections. The extensive scarring observed with hepatitis C infections and liver cirrhosis is the result of chronic inflammation. Check Your Understanding Name the five signs of inflammation. Is a granuloma an acute or chronic form of inflammation? Explain. Micro Connections Chronic Edema In addition to granulomas, chronic inflammation can also result in long-term edema. A condition known as lymphatic filariasis (also known as elephantiasis ) provides an extreme example. Lymphatic filariasis is caused by microscopic nematodes (parasitic worms) whose larvae are transmitted between human hosts by mosquitoes. Adult worms live in the lymphatic vessels, where their presence stimulates infiltration by lymphocytes, plasma cells, eosinophils, and thrombocytes (a condition known as lymphangitis). Because of the chronic nature of the illness, granulomas, fibrosis, and blocking of the lymphatic system may eventually occur. Over time, these blockages may worsen with repeated infections over decades, leading to skin thickened with edema and fibrosis. Lymph (extracellular tissue fluid) may spill out of the lymphatic areas and back into tissues, causing extreme swelling ( Figure 17.25 ). Secondary bacterial infections commonly follow. Because it is a disease caused by a parasite, eosinophilia (a dramatic rise in the number of eosinophils in the blood) is characteristic of acute infection. However, this increase in antiparasite granulocytes is not sufficient to clear the infection in many cases. Lymphatic filariasis affects an estimated 120 million people worldwide, mostly concentrated in Africa and Asia. 2 Improved sanitation and mosquito control can reduce transmission rates. 2 Centers for Disease Control and Prevention. “Parasites–Lymphatic Filiariasis.” 2016. http://www.cdc.gov/parasites/lymphaticfilariasis/gen_info/faqs.html. Fever A fever is an inflammatory response that extends beyond the site of infection and affects the entire body, resulting in an overall increase in body temperature. Body temperature is normally regulated and maintained by the hypothalamus, an anatomical section of the brain that functions to maintain homeostasis in the body. However, certain bacterial or viral infections can result in the production of pyrogens , chemicals that effectively alter the “thermostat setting” of the hypothalamus to elevate body temperature and cause fever. Pyrogens may be exogenous or endogenous. For example, the endotoxin lipopolysaccharide (LPS) , produced by gram-negative bacteria, is an exogenous pyrogen that may induce the leukocytes to release endogenous pyrogens such as interleukin-1 (IL-1), IL-6, interferon-γ (IFN-γ), and tumor necrosis factor (TNF). In a cascading effect, these molecules can then lead to the release of prostaglandin E2 (PGE 2 ) from other cells, resetting the hypothalamus to initiate fever ( Figure 17.26 ). Like other forms of inflammation, a fever enhances the innate immune defenses by stimulating leukocytes to kill pathogens. The rise in body temperature also may inhibit the growth of many pathogens since human pathogens are mesophiles with optimum growth occurring around 35 °C (95 °F). In addition, some studies suggest that fever may also stimulate release of iron-sequestering compounds from the liver, thereby starving out microbes that rely on iron for growth. 3 3 N. Parrow et al. “Sequestration and Scavenging of Iron in Infection.” Infection and Immunity 81 no. 10 (2013):3503–3514 During fever , the skin may appear pale due to vasoconstriction of the blood vessels in the skin, which is mediated by the hypothalamus to divert blood flow away from extremities, minimizing the loss of heat and raising the core temperature. The hypothalamus will also stimulate shivering of muscles, another effective mechanism of generating heat and raising the core temperature. The crisis phase occurs when the fever breaks. The hypothalamus stimulates vasodilation , resulting in a return of blood flow to the skin and a subsequent release of heat from the body. The hypothalamus also stimulates sweating, which cools the skin as the sweat evaporates. Although a low-level fever may help an individual overcome an illness, in some instances, this immune response can be too strong, causing tissue and organ damage and, in severe cases, even death. The inflammatory response to bacterial superantigens is one scenario in which a life-threatening fever may develop. Superantigens are bacterial or viral proteins that can cause an excessive activation of T cells from the specific adaptive immune defense, as well as an excessive release of cytokines that overstimulates the inflammatory response. For example, Staphylococcus aureus and Streptococcus pyogenes are capable of producing superantigens that cause toxic shock syndrome and scarlet fever , respectively. Both of these conditions can be associated with very high, life-threatening fevers in excess of 42 °C (108 °F). Check Your Understanding Explain the difference between exogenous and endogenous pyrogens. How does a fever inhibit pathogens? Clinical Focus Resolution Given her father’s premature death, Angela’s doctor suspects that she has hereditary angioedema , a genetic disorder that compromises the function of C1 inhibitor protein. Patients with this genetic abnormality may have occasional episodes of swelling in various parts of the body. In Angela’s case, the swelling has occurred in the respiratory tract, leading to difficulty breathing. Swelling may also occur in the gastrointestinal tract, causing abdominal cramping, diarrhea, and vomiting, or in the muscles of the face or limbs. This swelling may be nonresponsive to steroid treatment and is often misdiagnosed as an allergy. Because there are three types of hereditary angioedema, the doctor orders a more specific blood test to look for levels of C1-INH, as well as a functional assay of Angela’s C1 inhibitors. The results suggest that Angela has type I hereditary angioedema, which accounts for 80%–85% of all cases. This form of the disorder is caused by a deficiency in C1 esterase inhibitors, the proteins that normally help suppress activation of the complement system. When these proteins are deficient or nonfunctional, overstimulation of the system can lead to production of inflammatory anaphylatoxins, which results in swelling and fluid buildup in tissues. There is no cure for hereditary angioedema, but timely treatment with purified and concentrated C1-INH from blood donors can be effective, preventing tragic outcomes like the one suffered by Angela’s father. A number of therapeutic drugs, either currently approved or in late-stage human trials, may also be considered as options for treatment in the near future. These drugs work by inhibiting inflammatory molecules or the receptors for inflammatory molecules. Thankfully, Angela’s condition was quickly diagnosed and treated. Although she may experience additional episodes in the future, her prognosis is good and she can expect to live a relatively normal life provided she seeks treatment at the onset of symptoms. Go back to the previous Clinical Focus box.
biology
Chapter Outline 22.1 Prokaryotic Diversity 22.2 Structure of Prokaryotes 22.3 Prokaryotic Metabolism 22.4 Bacterial Diseases in Humans 22.5 Beneficial Prokaryotes Introduction In the recent past, scientists grouped living things into five kingdoms—animals, plants, fungi, protists, and prokaryotes—based on several criteria, such as the absence or presence of a nucleus and other membrane-bound organelles, the absence or presence of cell walls, multicellularity, and so on. In the late 20 th century, the pioneering work of Carl Woese and others compared sequences of small-subunit ribosomal RNA (SSU rRNA), which resulted in a more fundamental way to group organisms on Earth. Based on differences in the structure of cell membranes and in rRNA, Woese and his colleagues proposed that all life on Earth evolved along three lineages, called domains. The domain Bacteria comprises all organisms in the kingdom Bacteria, the domain Archaea comprises the rest of the prokaryotes, and the domain Eukarya comprises all eukaryotes—including organisms in the kingdoms Animalia, Plantae, Fungi, and Protista. Two of the three domains—Bacteria and Archaea—are prokaryotic. Prokaryotes were the first inhabitants on Earth, appearing 3.5 to 3.8 billion years ago. These organisms are abundant and ubiquitous; that is, they are present everywhere. In addition to inhabiting moderate environments, they are found in extreme conditions: from boiling springs to permanently frozen environments in Antarctica; from salty environments like the Dead Sea to environments under tremendous pressure, such as the depths of the ocean; and from areas without oxygen, such as a waste management plant, to radioactively contaminated regions, such as Chernobyl. Prokaryotes reside in the human digestive system and on the skin, are responsible for certain illnesses, and serve an important role in the preparation of many foods.
[ { "answer": { "ans_choice": 1, "ans_text": "prokaryotes" }, "bloom": null, "hl_context": "When and where did life begin ? What were the conditions on Earth when life began ? <hl> Prokaryotes were the first forms of life on Earth , and they existed for billions of years before plants and animals appeared . <hl> The Earth and its moon are thought to be about 4.54 billion years old . This estimate is based on evidence from radiometric dating of meteorite material together with other substrate material from Earth and the moon . Early Earth had a very different atmosphere ( contained less molecular oxygen ) than it does today and was subjected to strong radiation ; thus , the first organisms would have flourished where they were more protected , such as in ocean depths or beneath the surface of the Earth . At this time too , strong volcanic activity was common on Earth , so it is likely that these first organisms — the first prokaryotes — were adapted to very high temperatures . Early Earth was prone to geological upheaval and volcanic eruption , and was subject to bombardment by mutagenic radiation from the sun . The first organisms were prokaryotes that could withstand these harsh conditions .", "hl_sentences": "Prokaryotes were the first forms of life on Earth , and they existed for billions of years before plants and animals appeared .", "question": { "cloze_format": "The first forms of life on Earth were thought to be_________.", "normal_format": "Which were the first forms of life on Earth thought to be?", "question_choices": [ "single-celled plants", "prokaryotes", "insects", "large animals such as dinosaurs" ], "question_id": "fs-idm35076832", "question_text": "The first forms of life on Earth were thought to be_________." }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 3, "ans_text": "all of the above" }, "bloom": null, "hl_context": "The first microbial mats likely obtained their energy from chemicals found near hydrothermal vents . A hydrothermal vent is a breakage or fissure in the Earth ’ s surface that releases geothermally heated water . <hl> With the evolution of photosynthesis about 3 billion years ago , some prokaryotes in microbial mats came to use a more widely available energy source — sunlight — whereas others were still dependent on chemicals from hydrothermal vents for energy and food . <hl> <hl> Microbial mats or large biofilms may represent the earliest forms of life on Earth ; there is fossil evidence of their presence starting about 3.5 billion years ago . <hl> <hl> A microbial mat is a multi-layered sheet of prokaryotes ( Figure 22.2 ) that includes mostly bacteria , but also archaea . <hl> Microbial mats are a few centimeters thick , and they typically grow where different types of materials interface , mostly on moist surfaces . The various types of prokaryotes that comprise them carry out different metabolic pathways , and that is the reason for their various colors . Prokaryotes in a microbial mat are held together by a glue-like sticky substance that they secrete called extracellular matrix .", "hl_sentences": "With the evolution of photosynthesis about 3 billion years ago , some prokaryotes in microbial mats came to use a more widely available energy source — sunlight — whereas others were still dependent on chemicals from hydrothermal vents for energy and food . Microbial mats or large biofilms may represent the earliest forms of life on Earth ; there is fossil evidence of their presence starting about 3.5 billion years ago . A microbial mat is a multi-layered sheet of prokaryotes ( Figure 22.2 ) that includes mostly bacteria , but also archaea .", "question": { "cloze_format": "Microbial mats __________.", "normal_format": "Which of the following is correct about microbial mats?", "question_choices": [ "are the earliest forms of life on Earth", "obtained their energy and food from hydrothermal vents", "are multi-layered sheet of prokaryotes including mostly bacteria but also archaea", "all of the above" ], "question_id": "fs-idp163375200", "question_text": "Microbial mats __________." }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 0, "ans_text": "cyanobacteria" }, "bloom": null, "hl_context": "<hl> Evidence indicates that during the first two billion years of Earth ’ s existence , the atmosphere was anoxic , meaning that there was no molecular oxygen . <hl> <hl> Therefore , only those organisms that can grow without oxygen — anaerobic organisms — were able to live . <hl> <hl> Autotrophic organisms that convert solar energy into chemical energy are called phototrophs , and they appeared within one billion years of the formation of Earth . <hl> <hl> Then , cyanobacteria , also known as blue-green algae , evolved from these simple phototrophs one billion years later . <hl> <hl> Cyanobacteria ( Figure 22.4 ) began the oxygenation of the atmosphere . <hl> Increased atmospheric oxygen allowed the development of more efficient O 2 - utilizing catabolic pathways . It also opened up the land to increased colonization , because some O 2 is converted into O 3 ( ozone ) and ozone effectively absorbs the ultraviolet light that would otherwise cause lethal mutations in DNA . Ultimately , the increase in O 2 concentrations allowed the evolution of other life forms .", "hl_sentences": "Evidence indicates that during the first two billion years of Earth ’ s existence , the atmosphere was anoxic , meaning that there was no molecular oxygen . Therefore , only those organisms that can grow without oxygen — anaerobic organisms — were able to live . Autotrophic organisms that convert solar energy into chemical energy are called phototrophs , and they appeared within one billion years of the formation of Earth . Then , cyanobacteria , also known as blue-green algae , evolved from these simple phototrophs one billion years later . Cyanobacteria ( Figure 22.4 ) began the oxygenation of the atmosphere .", "question": { "cloze_format": "The first organisms that oxygenated the atmosphere were ___.", "normal_format": "What were the first organisms that oxygenated the atmosphere?", "question_choices": [ "cyanobacteria", "phototrophic organisms", "anaerobic organisms", "all of the above" ], "question_id": "fs-idp45747584", "question_text": "The first organisms that oxygenated the atmosphere were" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 0, "ans_text": "a salt concentration of at least 0.2 M" }, "bloom": null, "hl_context": "<hl> Salt concentration of at least 0.2 M <hl> <hl> Halophiles <hl>", "hl_sentences": "Salt concentration of at least 0.2 M Halophiles", "question": { "cloze_format": "Halophiles are organisms that require________.", "normal_format": "Halophiles are organisms that require which of the following?", "question_choices": [ "a salt concentration of at least 0.2 M", "high sugar concentration", "the addition of halogens", "all of the above" ], "question_id": "fs-idp124475872", "question_text": "Halophiles are organisms that require________." }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 1, "ans_text": "eukaryotic cells" }, "bloom": null, "hl_context": "<hl> There are many differences between prokaryotic and eukaryotic cells . <hl> <hl> However , all cells have four common structures : the plasma membrane , which functions as a barrier for the cell and separates the cell from its environment ; the cytoplasm , a jelly-like substance inside the cell ; nucleic acids , the genetic material of the cell ; and ribosomes , where protein synthesis takes place . <hl> Prokaryotes come in various shapes , but many fall into three categories : cocci ( spherical ) , bacilli ( rod-shaped ) , and spirilli ( spiral-shaped ) ( Figure 22.9 ) .", "hl_sentences": "There are many differences between prokaryotic and eukaryotic cells . However , all cells have four common structures : the plasma membrane , which functions as a barrier for the cell and separates the cell from its environment ; the cytoplasm , a jelly-like substance inside the cell ; nucleic acids , the genetic material of the cell ; and ribosomes , where protein synthesis takes place .", "question": { "cloze_format": "The presence of a membrane-enclosed nucleus is a characteristic of ________.", "normal_format": "The presence of a membrane-enclosed nucleus characterizes what?", "question_choices": [ "prokaryotic cells", "eukaryotic cells", "all cells", "viruses" ], "question_id": "fs-idp317200", "question_text": "The presence of a membrane-enclosed nucleus is a characteristic of ________." }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 3, "ans_text": "bacteria and archaea" }, "bloom": null, "hl_context": "<hl> The composition of the cell wall differs significantly between the domains Bacteria and Archaea . <hl> <hl> The composition of their cell walls also differs from the eukaryotic cell walls found in plants ( cellulose ) or fungi and insects ( chitin ) . <hl> <hl> The cell wall functions as a protective layer , and it is responsible for the organism ’ s shape . <hl> <hl> Some bacteria have an outer capsule outside the cell wall . <hl> <hl> Other structures are present in some prokaryotic species , but not in others ( Table 22.2 ) . <hl> For example , the capsule found in some species enables the organism to attach to surfaces , protects it from dehydration and attack by phagocytic cells , and makes pathogens more resistant to our immune responses . Some species also have flagella ( singular , flagellum ) used for locomotion , and pili ( singular , pilus ) used for attachment to surfaces . Plasmids , which consist of extra-chromosomal DNA , are also present in many species of bacteria and archaea .", "hl_sentences": "The composition of the cell wall differs significantly between the domains Bacteria and Archaea . The composition of their cell walls also differs from the eukaryotic cell walls found in plants ( cellulose ) or fungi and insects ( chitin ) . The cell wall functions as a protective layer , and it is responsible for the organism ’ s shape . Some bacteria have an outer capsule outside the cell wall . Other structures are present in some prokaryotic species , but not in others ( Table 22.2 ) .", "question": { "cloze_format": "___ consist of prokaryotic cells.", "normal_format": "Which of the following consist of prokaryotic cells?", "question_choices": [ "bacteria and fungi", "archaea and fungi", "protists and animals", "bacteria and archaea" ], "question_id": "fs-idp45217456", "question_text": "Which of the following consist of prokaryotic cells?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 1, "ans_text": "exterior to the cell membrane" }, "bloom": null, "hl_context": "The cytoplasm of prokaryotic cells has a high concentration of dissolved solutes . Therefore , the osmotic pressure within the cell is relatively high . <hl> The cell wall is a protective layer that surrounds some cells and gives them shape and rigidity . <hl> <hl> It is located outside the cell membrane and prevents osmotic lysis ( bursting due to increasing volume ) . <hl> The chemical composition of the cell walls varies between archaea and bacteria , and also varies between bacterial species .", "hl_sentences": "The cell wall is a protective layer that surrounds some cells and gives them shape and rigidity . It is located outside the cell membrane and prevents osmotic lysis ( bursting due to increasing volume ) .", "question": { "cloze_format": "The cell wall is ________.", "normal_format": "Which of the following is correct about the cell wall?", "question_choices": [ "interior to the cell membrane", "exterior to the cell membrane", "a part of the cell membrane", "interior or exterior, depending on the particular cell" ], "question_id": "fs-idm38396544", "question_text": "The cell wall is ________." }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 1, "ans_text": "bacteria" }, "bloom": null, "hl_context": "<hl> Other bacteria and archaea are adapted to grow under extreme conditions and are called extremophiles , meaning “ lovers of extremes . ” Extremophiles have been found in all kinds of environments : the depth of the oceans , hot springs , the Artic and the Antarctic , in very dry places , deep inside Earth , in harsh chemical environments , and in high radiation environments ( Figure 22.5 ) , just to mention a few . <hl> These organisms give us a better understanding of prokaryotic diversity and open up the possibility of finding new prokaryotic species that may lead to the discovery of new therapeutic drugs or have industrial applications . Because they have specialized adaptations that allow them to live in extreme conditions , many extremophiles cannot survive in moderate environments . There are many different groups of extremophiles : They are identified based on the conditions in which they grow best , and several habitats are extreme in multiple ways . For example , a soda lake is both salty and alkaline , so organisms that live in a soda lake must be both alkaliphiles and halophiles ( Table 22.1 ) . Other extremophiles , like radioresistant organisms , do not prefer an extreme environment ( in this case , one with high levels of radiation ) , but have adapted to survive in it ( Figure 22.5 ) . Chapter Outline 22.1 Prokaryotic Diversity 22.2 Structure of Prokaryotes 22.3 Prokaryotic Metabolism 22.4 Bacterial Diseases in Humans 22.5 Beneficial Prokaryotes Introduction In the recent past , scientists grouped living things into five kingdoms — animals , plants , fungi , protists , and prokaryotes — based on several criteria , such as the absence or presence of a nucleus and other membrane-bound organelles , the absence or presence of cell walls , multicellularity , and so on . In the late 20 th century , the pioneering work of Carl Woese and others compared sequences of small-subunit ribosomal RNA ( SSU rRNA ) , which resulted in a more fundamental way to group organisms on Earth . Based on differences in the structure of cell membranes and in rRNA , Woese and his colleagues proposed that all life on Earth evolved along three lineages , called domains . <hl> The domain Bacteria comprises all organisms in the kingdom Bacteria , the domain Archaea comprises the rest of the prokaryotes , and the domain Eukarya comprises all eukaryotes — including organisms in the kingdoms Animalia , Plantae , Fungi , and Protista . <hl> <hl> Two of the three domains — Bacteria and Archaea — are prokaryotic . <hl> Prokaryotes were the first inhabitants on Earth , appearing 3.5 to 3.8 billion years ago . <hl> These organisms are abundant and ubiquitous ; that is , they are present everywhere . <hl> <hl> In addition to inhabiting moderate environments , they are found in extreme conditions : from boiling springs to permanently frozen environments in Antarctica ; from salty environments like the Dead Sea to environments under tremendous pressure , such as the depths of the ocean ; and from areas without oxygen , such as a waste management plant , to radioactively contaminated regions , such as Chernobyl . <hl> Prokaryotes reside in the human digestive system and on the skin , are responsible for certain illnesses , and serve an important role in the preparation of many foods .", "hl_sentences": "Other bacteria and archaea are adapted to grow under extreme conditions and are called extremophiles , meaning “ lovers of extremes . ” Extremophiles have been found in all kinds of environments : the depth of the oceans , hot springs , the Artic and the Antarctic , in very dry places , deep inside Earth , in harsh chemical environments , and in high radiation environments ( Figure 22.5 ) , just to mention a few . The domain Bacteria comprises all organisms in the kingdom Bacteria , the domain Archaea comprises the rest of the prokaryotes , and the domain Eukarya comprises all eukaryotes — including organisms in the kingdoms Animalia , Plantae , Fungi , and Protista . Two of the three domains — Bacteria and Archaea — are prokaryotic . These organisms are abundant and ubiquitous ; that is , they are present everywhere . In addition to inhabiting moderate environments , they are found in extreme conditions : from boiling springs to permanently frozen environments in Antarctica ; from salty environments like the Dead Sea to environments under tremendous pressure , such as the depths of the ocean ; and from areas without oxygen , such as a waste management plant , to radioactively contaminated regions , such as Chernobyl .", "question": { "cloze_format": "Organisms most likely to be found in extreme environments are ________.", "normal_format": "What are organisms most likely to be found in extreme environments?", "question_choices": [ "fungi", "bacteria", "viruses", "archaea" ], "question_id": "fs-idm178498368", "question_text": "Organisms most likely to be found in extreme environments are ________." }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 0, "ans_text": "wall" }, "bloom": null, "hl_context": "Bacteria are divided into two major groups : Gram positive and Gram negative , based on their reaction to Gram staining . Note that all Gram-positive bacteria belong to one phylum ; bacteria in the other phyla ( Proteobacteria , Chlamydias , Spirochetes , Cyanobacteria , and others ) are Gram-negative . <hl> The Gram staining method is named after its inventor , Danish scientist Hans Christian Gram ( 1853 – 1938 ) . <hl> <hl> The different bacterial responses to the staining procedure are ultimately due to cell wall structure . <hl> Gram-positive organisms typically lack the outer membrane found in Gram-negative organisms ( Figure 22.15 ) . Up to 90 percent of the cell wall in Gram-positive bacteria is composed of peptidoglycan , and most of the rest is composed of acidic substances called teichoic acids . Teichoic acids may be covalently linked to lipids in the plasma membrane to form lipoteichoic acids . Lipoteichoic acids anchor the cell wall to the cell membrane . Gram-negative bacteria have a relatively thin cell wall composed of a few layers of peptidoglycan ( only 10 percent of the total cell wall ) , surrounded by an outer envelope containing lipopolysaccharides ( LPS ) and lipoproteins . This outer envelope is sometimes referred to as a second lipid bilayer . The chemistry of this outer envelope is very different , however , from that of the typical lipid bilayer that forms plasma membranes . Visual Connection", "hl_sentences": "The Gram staining method is named after its inventor , Danish scientist Hans Christian Gram ( 1853 – 1938 ) . The different bacterial responses to the staining procedure are ultimately due to cell wall structure .", "question": { "cloze_format": "Prokaryotes stain as Gram-positive or Gram-negative because of differences in the cell _______.", "normal_format": "Prokaryotes stain as Gram-positive or Gram-negative because of differences in which cell?", "question_choices": [ "wall", "cytoplasm", "nucleus", "chromosome" ], "question_id": "fs-idm223022752", "question_text": "Prokaryotes stain as Gram-positive or Gram-negative because of differences in the cell _______." }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 2, "ans_text": "archaean prokaryotic cells" }, "bloom": null, "hl_context": "Archaean cell walls do not have peptidoglycan . <hl> There are four different types of Archaean cell walls . <hl> <hl> One type is composed of pseudopeptidoglycan , which is similar to peptidoglycan in morphology but contains different sugars in the polysaccharide chain . <hl> The other three types of cell walls are composed of polysaccharides , glycoproteins , or pure protein .", "hl_sentences": "There are four different types of Archaean cell walls . One type is composed of pseudopeptidoglycan , which is similar to peptidoglycan in morphology but contains different sugars in the polysaccharide chain .", "question": { "cloze_format": "Pseudopeptidoglycan is a characteristic of the walls of ________.", "normal_format": "Pseudopeptidoglycan is a characteristic of which walls? ", "question_choices": [ "eukaryotic cells", "bacterial prokaryotic cells", "archaean prokaryotic cells", "bacterial and archaean prokaryotic cells" ], "question_id": "fs-idm99890064", "question_text": "Pseudopeptidoglycan is a characteristic of the walls of ________." }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 1, "ans_text": "Gram-negative bacteria" }, "bloom": null, "hl_context": "Bacteria are divided into two major groups : Gram positive and Gram negative , based on their reaction to Gram staining . Note that all Gram-positive bacteria belong to one phylum ; bacteria in the other phyla ( Proteobacteria , Chlamydias , Spirochetes , Cyanobacteria , and others ) are Gram-negative . The Gram staining method is named after its inventor , Danish scientist Hans Christian Gram ( 1853 – 1938 ) . The different bacterial responses to the staining procedure are ultimately due to cell wall structure . Gram-positive organisms typically lack the outer membrane found in Gram-negative organisms ( Figure 22.15 ) . Up to 90 percent of the cell wall in Gram-positive bacteria is composed of peptidoglycan , and most of the rest is composed of acidic substances called teichoic acids . Teichoic acids may be covalently linked to lipids in the plasma membrane to form lipoteichoic acids . Lipoteichoic acids anchor the cell wall to the cell membrane . <hl> Gram-negative bacteria have a relatively thin cell wall composed of a few layers of peptidoglycan ( only 10 percent of the total cell wall ) , surrounded by an outer envelope containing lipopolysaccharides ( LPS ) and lipoproteins . <hl> This outer envelope is sometimes referred to as a second lipid bilayer . The chemistry of this outer envelope is very different , however , from that of the typical lipid bilayer that forms plasma membranes . Visual Connection", "hl_sentences": "Gram-negative bacteria have a relatively thin cell wall composed of a few layers of peptidoglycan ( only 10 percent of the total cell wall ) , surrounded by an outer envelope containing lipopolysaccharides ( LPS ) and lipoproteins .", "question": { "cloze_format": "The lipopolysaccharide layer (LPS) is a characteristic of the wall of ________.", "normal_format": "The lipopolysaccharide layer (LPS) is a characteristic of the which wall? ", "question_choices": [ "archaean cells", "Gram-negative bacteria", "bacterial prokaryotic cells", "eukaryotic cells" ], "question_id": "fs-idm220121616", "question_text": "The lipopolysaccharide layer (LPS) is a characteristic of the wall of ________." }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 1, "ans_text": "calcium" }, "bloom": null, "hl_context": "In addition to these macronutrients , prokaryotes require various metallic elements in small amounts . <hl> These are referred to as micronutrients or trace elements . <hl> <hl> For example , iron is necessary for the function of the cytochromes involved in electron-transport reactions . <hl> <hl> Some prokaryotes require other elements — such as boron ( B ) , chromium ( Cr ) , and manganese ( Mn ) — primarily as enzyme cofactors . <hl>", "hl_sentences": "These are referred to as micronutrients or trace elements . For example , iron is necessary for the function of the cytochromes involved in electron-transport reactions . Some prokaryotes require other elements — such as boron ( B ) , chromium ( Cr ) , and manganese ( Mn ) — primarily as enzyme cofactors .", "question": { "cloze_format": "The element ___ is not a micronutrient.", "normal_format": "Which of the following elements is not a micronutrient?", "question_choices": [ "boron", "calcium", "chromium", "manganese" ], "question_id": "fs-idm73098672", "question_text": "Which of the following elements is not a micronutrient?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 2, "ans_text": "chemotrophs" }, "bloom": null, "hl_context": "Prokaryotes can use different sources of energy to assemble macromolecules from smaller molecules . Phototrophs ( or phototrophic organisms ) obtain their energy from sunlight . <hl> Chemotrophs ( or chemosynthetic organisms ) obtain their energy from chemical compounds . <hl> <hl> Chemotrophs that can use organic compounds as energy sources are called chemoorganotrophs . <hl> Those that can also use inorganic compounds as energy sources are called chemolitotrophs .", "hl_sentences": "Chemotrophs ( or chemosynthetic organisms ) obtain their energy from chemical compounds . Chemotrophs that can use organic compounds as energy sources are called chemoorganotrophs .", "question": { "cloze_format": "Prokaryotes that obtain their energy from chemical compounds are called _____.", "normal_format": "What are prokaryotes that obtain their energy from chemical compounds called?", "question_choices": [ "phototrophs", "auxotrophs", "chemotrophs", "lithotrophs" ], "question_id": "fs-idm97968528", "question_text": "Prokaryotes that obtain their energy from chemical compounds are called _____." }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 0, "ans_text": "ammonia is released during the decomposition of nitrogen-containing organic compounds" }, "bloom": null, "hl_context": "Nitrogen is a very important element for life because it is part of proteins and nucleic acids . It is a macronutrient , and in nature , it is recycled from organic compounds to ammonia , ammonium ions , nitrate , nitrite , and nitrogen gas by myriad processes , many of which are carried out only by prokaryotes . As illustrated in Figure 22.19 , prokaryotes are key to the nitrogen cycle . The largest pool of nitrogen available in the terrestrial ecosystem is gaseous nitrogen from the air , but this nitrogen is not usable by plants , which are primary producers . Gaseous nitrogen is transformed , or “ fixed ” into more readily available forms such as ammonia through the process of nitrogen fixation . <hl> Ammonia can be used by plants or converted to other forms . <hl> <hl> Another source of ammonia is ammonification , the process by which ammonia is released during the decomposition of nitrogen-containing organic compounds . <hl> Ammonia released to the atmosphere , however , represents only 15 percent of the total nitrogen released ; the rest is as N 2 and N 2 O . Ammonia is catabolized anaerobically by some prokaryotes , yielding N 2 as the final product . Nitrification is the conversion of ammonium to nitrite and nitrate . Nitrification in soils is carried out by bacteria belonging to the genera Nitrosomas , Nitrobacter , and Nitrospira . The bacteria performs the reverse process , the reduction of nitrate from the soils to gaseous compounds such as N 2 O , NO , and N 2 , a process called denitrification . Visual Connection", "hl_sentences": "Ammonia can be used by plants or converted to other forms . Another source of ammonia is ammonification , the process by which ammonia is released during the decomposition of nitrogen-containing organic compounds .", "question": { "cloze_format": "Ammonification is the process by which _____.", "normal_format": "What is ammonification?", "question_choices": [ "ammonia is released during the decomposition of nitrogen-containing organic compounds", "ammonium is converted to nitrite and nitrate in soils", "nitrate from soil is transformed to gaseous nitrogen compounds such as NO, N2O, and N2", "gaseous nitrogen is fixed to yield ammonia" ], "question_id": "fs-idm27200192", "question_text": "Ammonification is the process by which _____." }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 1, "ans_text": "producers" }, "bloom": null, "hl_context": "<hl> A large amount of available carbon is found in land plants . <hl> <hl> Plants , which are producers , use carbon dioxide from the air to synthesize carbon compounds . <hl> Related to this , one very significant source of carbon compounds is humus , which is a mixture of organic materials from dead plants and prokaryotes that have resisted decomposition . Consumers such as animals use organic compounds generated by producers and release carbon dioxide to the atmosphere . Then , bacteria and fungi , collectively called decomposers , carry out the breakdown ( decomposition ) of plants and animals and their organic compounds . The most important contributor of carbon dioxide to the atmosphere is microbial decomposition of dead material ( dead animals , plants , and humus ) that undergo respiration .", "hl_sentences": "A large amount of available carbon is found in land plants . Plants , which are producers , use carbon dioxide from the air to synthesize carbon compounds .", "question": { "cloze_format": "Plants use carbon dioxide from the air and are therefore called _____.", "normal_format": "Plants use carbon dioxide from the air and are therefore called what?", "question_choices": [ "consumers", "producers", "decomposer", "carbon fixers" ], "question_id": "fs-idm83225968", "question_text": "Plants use carbon dioxide from the air and are therefore called _____." }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 1, "ans_text": "epidemic" }, "bloom": null, "hl_context": "Epidemiologists study how diseases affect a population . <hl> An epidemic is a disease that occurs in an unusually high number of individuals in a population at the same time . <hl> <hl> A pandemic is a widespread , usually worldwide , epidemic . <hl> An endemic disease is a disease that is constantly present , usually at low incidence , in a population .", "hl_sentences": "An epidemic is a disease that occurs in an unusually high number of individuals in a population at the same time . A pandemic is a widespread , usually worldwide , epidemic .", "question": { "cloze_format": "A disease that is constantly present in a population is called _____.", "normal_format": "What is a disease that is constantly present in a population called?", "question_choices": [ "pandemic", "epidemic", "endemic", "re-emerging" ], "question_id": "fs-idp166702752", "question_text": "A disease that is constantly present in a population is called _____." }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 3, "ans_text": "All statements are incorrect." }, "bloom": null, "hl_context": "<hl> Recall that biofilms are microbial communities that are very difficult to destroy . <hl> <hl> They are responsible for diseases such as infections in patients with cystic fibrosis , Legionnaires ’ disease , and otitis media . <hl> <hl> They produce dental plaque and colonize catheters , prostheses , transcutaneous and orthopedic devices , contact lenses , and internal devices such as pacemakers . <hl> <hl> They also form in open wounds and burned tissue . <hl> In healthcare environments , biofilms grow on hemodialysis machines , mechanical ventilators , shunts , and other medical equipment . In fact , 65 percent of all infections acquired in the hospital ( nosocomial infections ) are attributed to biofilms . Biofilms are also related to diseases contracted from food because they colonize the surfaces of vegetable leaves and meat , as well as food-processing equipment that isn ’ t adequately cleaned .", "hl_sentences": "Recall that biofilms are microbial communities that are very difficult to destroy . They are responsible for diseases such as infections in patients with cystic fibrosis , Legionnaires ’ disease , and otitis media . They produce dental plaque and colonize catheters , prostheses , transcutaneous and orthopedic devices , contact lenses , and internal devices such as pacemakers . They also form in open wounds and burned tissue .", "question": { "cloze_format": "The false statement about biofilms is that ___ .", "normal_format": "Which of the statements about biofilms is incorrect?", "question_choices": [ "Biofilms are considered responsible for diseases such as cystic fibrosis.", "Biofilms produce dental plaque, and colonize catheters and prostheses.", "Biofilms colonize open wounds and burned tissue.", "All statements are incorrect." ], "question_id": "fs-idp17951280", "question_text": "Which of the statements about biofilms is incorrect?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 3, "ans_text": "All of the above occur." }, "bloom": null, "hl_context": "Cyanobacteria are the most important nitrogen fixers in aquatic environments . In soil , members of the genus Clostridium are examples of free-living , nitrogen-fixing bacteria . Other bacteria live symbiotically with legume plants , providing the most important source of BNF . Symbionts may fix more nitrogen in soils than free-living organisms by a factor of 10 . <hl> Soil bacteria , collectively called rhizobia , are able to symbiotically interact with legumes to form nodules , specialized structures where nitrogen fixation occurs ( Figure 22.27 ) . <hl> <hl> Nitrogenase , the enzyme that fixes nitrogen , is inactivated by oxygen , so the nodule provides an oxygen-free area for nitrogen fixation to take place . <hl> <hl> This process provides a natural and inexpensive plant fertilizer , as it reduces atmospheric nitrogen to ammonia , which is easily usable by plants . <hl> The use of legumes is an excellent alternative to chemical fertilization and is of special interest to sustainable agriculture , which seeks to minimize the use of chemicals and conserve natural resources . Through symbiotic nitrogen fixation , the plant benefits from using an endless source of nitrogen : the atmosphere . <hl> Bacteria benefit from using photosynthates ( carbohydrates produced during photosynthesis ) from the plant and having a protected niche . <hl> Additionally , the soil benefits from being naturally fertilized . <hl> Therefore , the use of rhizobia as biofertilizers is a sustainable practice . <hl> Why are legumes so important ? Some , like soybeans , are key sources of agricultural protein . Some of the most important grain legumes are soybean , peanuts , peas , chickpeas , and beans . Other legumes , such as alfalfa , are used to feed cattle .", "hl_sentences": "Soil bacteria , collectively called rhizobia , are able to symbiotically interact with legumes to form nodules , specialized structures where nitrogen fixation occurs ( Figure 22.27 ) . Nitrogenase , the enzyme that fixes nitrogen , is inactivated by oxygen , so the nodule provides an oxygen-free area for nitrogen fixation to take place . This process provides a natural and inexpensive plant fertilizer , as it reduces atmospheric nitrogen to ammonia , which is easily usable by plants . Bacteria benefit from using photosynthates ( carbohydrates produced during photosynthesis ) from the plant and having a protected niche . Therefore , the use of rhizobia as biofertilizers is a sustainable practice .", "question": { "cloze_format": "It occurs through symbiotic nitrogen fixation that ___.", "normal_format": "Which of these occurs through symbiotic nitrogen fixation?", "question_choices": [ "The plant benefits from using an endless source of nitrogen.", "The soil benefits from being naturally fertilized.", "Bacteria benefit from using photosynthates from the plant.", "All of the above occur." ], "question_id": "fs-idm24905408", "question_text": "Which of these occurs through symbiotic nitrogen fixation?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 1, "ans_text": "the use of prokaryotes to clean up pollutants" }, "bloom": null, "hl_context": "<hl> Microbial bioremediation is the use of prokaryotes ( or microbial metabolism ) to remove pollutants . <hl> Bioremediation has been used to remove agricultural chemicals ( pesticides , fertilizers ) that leach from soil into groundwater and the subsurface . Certain toxic metals and oxides , such as selenium and arsenic compounds , can also be removed from water by bioremediation . The reduction of SeO 4 - 2 to SeO 3 - 2 and to Se 0 ( metallic selenium ) is a method used to remove selenium ions from water . Mercury is an example of a toxic metal that can be removed from an environment by bioremediation . As an active ingredient of some pesticides , mercury is used in industry and is also a by-product of certain processes , such as battery production . Methyl mercury is usually present in very low concentrations in natural environments , but it is highly toxic because it accumulates in living tissues . Several species of bacteria can carry out the biotransformation of toxic mercury into nontoxic forms . These bacteria , such as Pseudomonas aeruginosa , can convert Hg + 2 into Hg 0 , which is nontoxic to humans .", "hl_sentences": "Microbial bioremediation is the use of prokaryotes ( or microbial metabolism ) to remove pollutants .", "question": { "cloze_format": "Bioremediation includes _____.", "normal_format": "What does bioremediation include?", "question_choices": [ "the use of prokaryotes that can fix nitrogen", "the use of prokaryotes to clean up pollutants", "the use of prokaryotes as natural fertilizers", "All of the above" ], "question_id": "fs-idm36358320", "question_text": "Bioremediation includes _____." }, "references_are_paraphrase": null } ]
22
22.1 Prokaryotic Diversity Learning Objectives By the end of this section, you will be able to: Describe the evolutionary history of prokaryotes Discuss the distinguishing features of extremophiles Explain why it is difficult to culture prokaryotes Prokaryotes are ubiquitous. They cover every imaginable surface where there is sufficient moisture, and they live on and inside of other living things. In the typical human body, prokaryotic cells outnumber human body cells by about ten to one. They comprise the majority of living things in all ecosystems. Some prokaryotes thrive in environments that are inhospitable for most living things. Prokaryotes recycle nutrients —essential substances (such as carbon and nitrogen)—and they drive the evolution of new ecosystems, some of which are natural and others man-made. Prokaryotes have been on Earth since long before multicellular life appeared. Prokaryotes, the First Inhabitants of Earth When and where did life begin? What were the conditions on Earth when life began? Prokaryotes were the first forms of life on Earth, and they existed for billions of years before plants and animals appeared. The Earth and its moon are thought to be about 4.54 billion years old. This estimate is based on evidence from radiometric dating of meteorite material together with other substrate material from Earth and the moon. Early Earth had a very different atmosphere (contained less molecular oxygen) than it does today and was subjected to strong radiation; thus, the first organisms would have flourished where they were more protected, such as in ocean depths or beneath the surface of the Earth. At this time too, strong volcanic activity was common on Earth, so it is likely that these first organisms—the first prokaryotes—were adapted to very high temperatures. Early Earth was prone to geological upheaval and volcanic eruption, and was subject to bombardment by mutagenic radiation from the sun. The first organisms were prokaryotes that could withstand these harsh conditions. Microbial Mats Microbial mats or large biofilms may represent the earliest forms of life on Earth; there is fossil evidence of their presence starting about 3.5 billion years ago. A microbial mat is a multi-layered sheet of prokaryotes ( Figure 22.2 ) that includes mostly bacteria, but also archaea. Microbial mats are a few centimeters thick, and they typically grow where different types of materials interface, mostly on moist surfaces. The various types of prokaryotes that comprise them carry out different metabolic pathways, and that is the reason for their various colors. Prokaryotes in a microbial mat are held together by a glue-like sticky substance that they secrete called extracellular matrix. The first microbial mats likely obtained their energy from chemicals found near hydrothermal vents. A hydrothermal vent is a breakage or fissure in the Earth’s surface that releases geothermally heated water. With the evolution of photosynthesis about 3 billion years ago, some prokaryotes in microbial mats came to use a more widely available energy source—sunlight—whereas others were still dependent on chemicals from hydrothermal vents for energy and food. Stromatolites Fossilized microbial mats represent the earliest record of life on Earth. A stromatolite is a sedimentary structure formed when minerals are precipitated out of water by prokaryotes in a microbial mat ( Figure 22.3 ). Stromatolites form layered rocks made of carbonate or silicate. Although most stromatolites are artifacts from the past, there are places on Earth where stromatolites are still forming. For example, growing stromatolites have been found in the Anza-Borrego Desert State Park in San Diego County, California. The Ancient Atmosphere Evidence indicates that during the first two billion years of Earth’s existence, the atmosphere was anoxic , meaning that there was no molecular oxygen. Therefore, only those organisms that can grow without oxygen— anaerobic organisms—were able to live. Autotrophic organisms that convert solar energy into chemical energy are called phototrophs , and they appeared within one billion years of the formation of Earth. Then, cyanobacteria , also known as blue-green algae, evolved from these simple phototrophs one billion years later. Cyanobacteria ( Figure 22.4 ) began the oxygenation of the atmosphere. Increased atmospheric oxygen allowed the development of more efficient O 2 -utilizing catabolic pathways. It also opened up the land to increased colonization, because some O 2 is converted into O 3 (ozone) and ozone effectively absorbs the ultraviolet light that would otherwise cause lethal mutations in DNA. Ultimately, the increase in O 2 concentrations allowed the evolution of other life forms. Microbes Are Adaptable: Life in Moderate and Extreme Environments Some organisms have developed strategies that allow them to survive harsh conditions. Prokaryotes thrive in a vast array of environments: Some grow in conditions that would seem very normal to us, whereas others are able to thrive and grow under conditions that would kill a plant or animal. Almost all prokaryotes have a cell wall, a protective structure that allows them to survive in both hyper- and hypo-osmotic conditions. Some soil bacteria are able to form endospores that resist heat and drought, thereby allowing the organism to survive until favorable conditions recur. These adaptations, along with others, allow bacteria to be the most abundant life form in all terrestrial and aquatic ecosystems. Other bacteria and archaea are adapted to grow under extreme conditions and are called extremophiles , meaning “lovers of extremes.” Extremophiles have been found in all kinds of environments: the depth of the oceans, hot springs, the Artic and the Antarctic, in very dry places, deep inside Earth, in harsh chemical environments, and in high radiation environments ( Figure 22.5 ), just to mention a few. These organisms give us a better understanding of prokaryotic diversity and open up the possibility of finding new prokaryotic species that may lead to the discovery of new therapeutic drugs or have industrial applications. Because they have specialized adaptations that allow them to live in extreme conditions, many extremophiles cannot survive in moderate environments. There are many different groups of extremophiles: They are identified based on the conditions in which they grow best, and several habitats are extreme in multiple ways. For example, a soda lake is both salty and alkaline, so organisms that live in a soda lake must be both alkaliphiles and halophiles ( Table 22.1 ). Other extremophiles, like radioresistant organisms, do not prefer an extreme environment (in this case, one with high levels of radiation), but have adapted to survive in it ( Figure 22.5 ). Extremophiles and Their Preferred Conditions Extremophile Type Conditions for Optimal Growth Acidophiles pH 3 or below Alkaliphiles pH 9 or above Thermophiles Temperature 60–80 °C (140–176 °F) Hyperthermophiles Temperature 80–122 °C (176–250 °F) Psychrophiles Temperature of -15-10 °C (5-50 °F) or lower Halophiles Salt concentration of at least 0.2 M Osmophiles High sugar concentration Table 22.1 Prokaryotes in the Dead Sea One example of a very harsh environment is the Dead Sea, a hypersaline basin that is located between Jordan and Israel. Hypersaline environments are essentially concentrated seawater. In the Dead Sea, the sodium concentration is 10 times higher than that of seawater, and the water contains high levels of magnesium (about 40 times higher than in seawater) that would be toxic to most living things. Iron, calcium, and magnesium, elements that form divalent ions (Fe 2+ , Ca 2+ , and Mg 2+ ), produce what is commonly referred to as “hard” water. Taken together, the high concentration of divalent cations, the acidic pH (6.0), and the intense solar radiation flux make the Dead Sea a unique, and uniquely hostile, ecosystem 1 ( Figure 22.6 ). 1 Bodaker, I, Itai, S, Suzuki, MT, Feingersch, R, Rosenberg, M, Maguire, ME, Shimshon, B, and others. Comparative community genomics in the Dead Sea: An increasingly extreme environment. The ISME Journal 4 (2010): 399–407, doi:10.1038/ismej.2009.141 . published online 24 December 2009. What sort of prokaryotes do we find in the Dead Sea? The extremely salt-tolerant bacterial mats include Halobacterium , Haloferax volcanii (which is found in other locations, not only the Dead Sea), Halorubrum sodomense , and Halobaculum gomorrense , and the archaea Haloarcula marismortui , among others. Unculturable Prokaryotes and the Viable-but-Non-Culturable State Microbiologists typically grow prokaryotes in the laboratory using an appropriate culture medium containing all the nutrients needed by the target organism. The medium can be liquid, broth, or solid. After an incubation time at the right temperature, there should be evidence of microbial growth ( Figure 22.7 ). The process of culturing bacteria is complex and is one of the greatest discoveries of modern science. German physician Robert Koch is credited with discovering the techniques for pure culture, including staining and using growth media. His assistant Julius Petri invented the Petri dish whose use persists in today’s laboratories. Koch worked primarily with the Mycobacterium tuberculosis bacterium that causes tuberculosis and developed postulates to identify disease-causing organisms that continue to be widely used in the medical community. Koch’s postulates include that an organism can be identified as the cause of disease when it is present in all infected samples and absent in all healthy samples, and it is able to reproduce the infection after being cultured multiple times. Today, cultures remain a primary diagnostic tool in medicine and other areas of molecular biology. Some prokaryotes, however, cannot grow in a laboratory setting. In fact, over 99 percent of bacteria and archaea are unculturable. For the most part, this is due to a lack of knowledge as to what to feed these organisms and how to grow them; they have special requirements for growth that remain unknown to scientists, such as needing specific micronutrients, pH, temperature, pressure, co-factors, or co-metabolites. Some bacteria cannot be cultured because they are obligate intracellular parasites and cannot be grown outside a host cell. In other cases, culturable organisms become unculturable under stressful conditions, even though the same organism could be cultured previously. Those organisms that cannot be cultured but are not dead are in a viable-but-non-culturable (VBNC) state. The VBNC state occurs when prokaryotes respond to environmental stressors by entering a dormant state that allows their survival. The criteria for entering into the VBNC state are not completely understood. In a process called resuscitation , the prokaryote can go back to “normal” life when environmental conditions improve. Is the VBNC state an unusual way of living for prokaryotes? In fact, most of the prokaryotes living in the soil or in oceanic waters are non-culturable. It has been said that only a small fraction, perhaps one percent, of prokaryotes can be cultured under laboratory conditions. If these organisms are non-culturable, then how is it known whether they are present and alive? Microbiologists use molecular techniques, such as the polymerase chain reaction (PCR), to amplify selected portions of DNA of prokaryotes, demonstrating their existence. Recall that PCR can make billions of copies of a DNA segment in a process called amplification. The Ecology of Biofilms Until a couple of decades ago, microbiologists used to think of prokaryotes as isolated entities living apart. This model, however, does not reflect the true ecology of prokaryotes, most of which prefer to live in communities where they can interact. A biofilm is a microbial community ( Figure 22.8 ) held together in a gummy-textured matrix that consists primarily of polysaccharides secreted by the organisms, together with some proteins and nucleic acids. Biofilms grow attached to surfaces. Some of the best-studied biofilms are composed of prokaryotes, although fungal biofilms have also been described as well as some composed of a mixture of fungi and bacteria. Biofilms are present almost everywhere: they can cause the clogging of pipes and readily colonize surfaces in industrial settings. In recent, large-scale outbreaks of bacterial contamination of food, biofilms have played a major role. They also colonize household surfaces, such as kitchen counters, cutting boards, sinks, and toilets, as well as places on the human body, such as the surfaces of our teeth. Interactions among the organisms that populate a biofilm, together with their protective exopolysaccharidic (EPS) environment, make these communities more robust than free-living, or planktonic, prokaryotes. The sticky substance that holds bacteria together also excludes most antibiotics and disinfectants, making biofilm bacteria hardier than their planktonic counterparts. Overall, biofilms are very difficult to destroy because they are resistant to many common forms of sterilization. Visual Connection Compared to free-floating bacteria, bacteria in biofilms often show increased resistance to antibiotics and detergents. Why do you think this might be the case? 22.2 Structure of Prokaryotes Learning Objectives By the end of this section, you will be able to: Describe the basic structure of a typical prokaryote Describe important differences in structure between Archaea and Bacteria There are many differences between prokaryotic and eukaryotic cells. However, all cells have four common structures: the plasma membrane, which functions as a barrier for the cell and separates the cell from its environment; the cytoplasm, a jelly-like substance inside the cell; nucleic acids, the genetic material of the cell; and ribosomes, where protein synthesis takes place. Prokaryotes come in various shapes, but many fall into three categories: cocci (spherical), bacilli (rod-shaped), and spirilli (spiral-shaped) ( Figure 22.9 ). The Prokaryotic Cell Recall that prokaryotes ( Figure 22.10 ) are unicellular organisms that lack organelles or other internal membrane-bound structures. Therefore, they do not have a nucleus but instead generally have a single chromosome—a piece of circular, double-stranded DNA located in an area of the cell called the nucleoid. Most prokaryotes have a cell wall outside the plasma membrane. Recall that prokaryotes are divided into two different domains, Bacteria and Archaea, which together with Eukarya, comprise the three domains of life ( Figure 22.11 ). The composition of the cell wall differs significantly between the domains Bacteria and Archaea. The composition of their cell walls also differs from the eukaryotic cell walls found in plants (cellulose) or fungi and insects (chitin). The cell wall functions as a protective layer, and it is responsible for the organism’s shape. Some bacteria have an outer capsule outside the cell wall. Other structures are present in some prokaryotic species, but not in others ( Table 22.2 ). For example, the capsule found in some species enables the organism to attach to surfaces, protects it from dehydration and attack by phagocytic cells, and makes pathogens more resistant to our immune responses. Some species also have flagella (singular, flagellum) used for locomotion, and pili (singular, pilus) used for attachment to surfaces. Plasmids, which consist of extra-chromosomal DNA, are also present in many species of bacteria and archaea. Characteristics of phyla of Bacteria are described in Figure 22.12 and Figure 22.13 ; Archaea are described in Figure 22.14 . The Plasma Membrane The plasma membrane is a thin lipid bilayer (6 to 8 nanometers) that completely surrounds the cell and separates the inside from the outside. Its selectively permeable nature keeps ions, proteins, and other molecules within the cell and prevents them from diffusing into the extracellular environment, while other molecules may move through the membrane. Recall that the general structure of a cell membrane is a phospholipid bilayer composed of two layers of lipid molecules. In archaeal cell membranes, isoprene (phytanyl) chains linked to glycerol replace the fatty acids linked to glycerol in bacterial membranes. Some archaeal membranes are lipid monolayers instead of bilayers ( Figure 22.14 ). The Cell Wall The cytoplasm of prokaryotic cells has a high concentration of dissolved solutes. Therefore, the osmotic pressure within the cell is relatively high. The cell wall is a protective layer that surrounds some cells and gives them shape and rigidity. It is located outside the cell membrane and prevents osmotic lysis (bursting due to increasing volume). The chemical composition of the cell walls varies between archaea and bacteria, and also varies between bacterial species. Bacterial cell walls contain peptidoglycan , composed of polysaccharide chains that are cross-linked by unusual peptides containing both L- and D-amino acids including D-glutamic acid and D-alanine. Proteins normally have only L-amino acids; as a consequence, many of our antibiotics work by mimicking D-amino acids and therefore have specific effects on bacterial cell wall development. There are more than 100 different forms of peptidoglycan. S-layer (surface layer) proteins are also present on the outside of cell walls of both archaea and bacteria. Bacteria are divided into two major groups: Gram positive and Gram negative , based on their reaction to Gram staining. Note that all Gram-positive bacteria belong to one phylum; bacteria in the other phyla (Proteobacteria, Chlamydias, Spirochetes, Cyanobacteria, and others) are Gram-negative. The Gram staining method is named after its inventor, Danish scientist Hans Christian Gram (1853–1938). The different bacterial responses to the staining procedure are ultimately due to cell wall structure. Gram-positive organisms typically lack the outer membrane found in Gram-negative organisms ( Figure 22.15 ). Up to 90 percent of the cell wall in Gram-positive bacteria is composed of peptidoglycan, and most of the rest is composed of acidic substances called teichoic acids . Teichoic acids may be covalently linked to lipids in the plasma membrane to form lipoteichoic acids. Lipoteichoic acids anchor the cell wall to the cell membrane. Gram-negative bacteria have a relatively thin cell wall composed of a few layers of peptidoglycan (only 10 percent of the total cell wall), surrounded by an outer envelope containing lipopolysaccharides (LPS) and lipoproteins. This outer envelope is sometimes referred to as a second lipid bilayer. The chemistry of this outer envelope is very different, however, from that of the typical lipid bilayer that forms plasma membranes. Visual Connection Which of the following statements is true? Gram-positive bacteria have a single cell wall anchored to the cell membrane by lipoteichoic acid. Porins allow entry of substances into both Gram-positive and Gram-negative bacteria. The cell wall of Gram-negative bacteria is thick, and the cell wall of Gram-positive bacteria is thin. Gram-negative bacteria have a cell wall made of peptidoglycan, whereas Gram-positive bacteria have a cell wall made of lipoteichoic acid. Archaean cell walls do not have peptidoglycan. There are four different types of Archaean cell walls. One type is composed of pseudopeptidoglycan , which is similar to peptidoglycan in morphology but contains different sugars in the polysaccharide chain. The other three types of cell walls are composed of polysaccharides, glycoproteins, or pure protein. Structural Differences and Similarities between Bacteria and Archaea Structural Characteristic Bacteria Archaea Cell type Prokaryotic Prokaryotic Cell morphology Variable Variable Cell wall Contains peptidoglycan Does not contain peptidoglycan Cell membrane type Lipid bilayer Lipid bilayer or lipid monolayer Plasma membrane lipids Fatty acids Phytanyl groups Table 22.2 Reproduction Reproduction in prokaryotes is asexual and usually takes place by binary fission. Recall that the DNA of a prokaryote exists as a single, circular chromosome. Prokaryotes do not undergo mitosis. Rather the chromosome is replicated and the two resulting copies separate from one another, due to the growth of the cell. The prokaryote, now enlarged, is pinched inward at its equator and the two resulting cells, which are clones, separate. Binary fission does not provide an opportunity for genetic recombination or genetic diversity, but prokaryotes can share genes by three other mechanisms. In transformation , the prokaryote takes in DNA found in its environment that is shed by other prokaryotes. If a nonpathogenic bacterium takes up DNA for a toxin gene from a pathogen and incorporates the new DNA into its own chromosome, it too may become pathogenic. In transduction , bacteriophages, the viruses that infect bacteria, sometimes also move short pieces of chromosomal DNA from one bacterium to another. Transduction results in a recombinant organism. Archaea are not affected by bacteriophages but instead have their own viruses that translocate genetic material from one individual to another. In conjugation , DNA is transferred from one prokaryote to another by means of a pilus, which brings the organisms into contact with one another. The DNA transferred can be in the form of a plasmid or as a hybrid, containing both plasmid and chromosomal DNA. These three processes of DNA exchange are shown in Figure 22.17 . Reproduction can be very rapid: a few minutes for some species. This short generation time coupled with mechanisms of genetic recombination and high rates of mutation result in the rapid evolution of prokaryotes, allowing them to respond to environmental changes (such as the introduction of an antibiotic) very quickly. Evolution Connection The Evolution of Prokaryotes How do scientists answer questions about the evolution of prokaryotes? Unlike with animals, artifacts in the fossil record of prokaryotes offer very little information. Fossils of ancient prokaryotes look like tiny bubbles in rock. Some scientists turn to genetics and to the principle of the molecular clock, which holds that the more recently two species have diverged, the more similar their genes (and thus proteins) will be. Conversely, species that diverged long ago will have more genes that are dissimilar. Scientists at the NASA Astrobiology Institute and at the European Molecular Biology Laboratory collaborated to analyze the molecular evolution of 32 specific proteins common to 72 species of prokaryotes. 2 The model they derived from their data indicates that three important groups of bacteria—Actinobacteria, Deinococcus , and Cyanobacteria (which the authors call Terrabacteria )—were the first to colonize land. (Recall that Deinococcus is a genus of prokaryote—a bacterium—that is highly resistant to ionizing radiation.) Cyanobacteria are photosynthesizers, while Actinobacteria are a group of very common bacteria that include species important in decomposition of organic wastes. 2 Battistuzzi, FU, Feijao, A, and Hedges, SB. A genomic timescale of prokaryote evolution: Insights into the origin of methanogenesis, phototrophy, and the colonization of land. BioMed Central: Evolutionary Biology 4 (2004): 44, doi:10.1186/1471-2148-4-44. The timelines of divergence suggest that bacteria (members of the domain Bacteria) diverged from common ancestral species between 2.5 and 3.2 billion years ago, whereas archaea diverged earlier: between 3.1 and 4.1 billion years ago. Eukarya later diverged off the Archaean line. The work further suggests that stromatolites that formed prior to the advent of cyanobacteria (about 2.6 billion years ago) photosynthesized in an anoxic environment and that because of the modifications of the Terrabacteria for land (resistance to drying and the possession of compounds that protect the organism from excess light), photosynthesis using oxygen may be closely linked to adaptations to survive on land. 22.3 Prokaryotic Metabolism Learning Objectives By the end of this section, you will be able to: Identify the macronutrients needed by prokaryotes, and explain their importance Describe the ways in which prokaryotes get energy and carbon for life processes Describe the roles of prokaryotes in the carbon and nitrogen cycles Prokaryotes are metabolically diverse organisms. There are many different environments on Earth with various energy and carbon sources, and variable conditions. Prokaryotes have been able to live in every environment by using whatever energy and carbon sources are available. Prokaryotes fill many niches on Earth, including being involved in nutrient cycles such as nitrogen and carbon cycles, decomposing dead organisms, and thriving inside living organisms, including humans. The very broad range of environments that prokaryotes occupy is possible because they have diverse metabolic processes. Needs of Prokaryotes The diverse environments and ecosystems on Earth have a wide range of conditions in terms of temperature, available nutrients, acidity, salinity, and energy sources. Prokaryotes are very well equipped to make their living out of a vast array of nutrients and conditions. To live, prokaryotes need a source of energy, a source of carbon, and some additional nutrients. Macronutrients Cells are essentially a well-organized assemblage of macromolecules and water. Recall that macromolecules are produced by the polymerization of smaller units called monomers. For cells to build all of the molecules required to sustain life, they need certain substances, collectively called nutrients . When prokaryotes grow in nature, they obtain their nutrients from the environment. Nutrients that are required in large amounts are called macronutrients, whereas those required in smaller or trace amounts are called micronutrients. Just a handful of elements are considered macronutrients—carbon, hydrogen, oxygen, nitrogen, phosphorus, and sulfur. (A mnemonic for remembering these elements is the acronym CHONPS .) Why are these macronutrients needed in large amounts? They are the components of organic compounds in cells, including water. Carbon is the major element in all macromolecules: carbohydrates, proteins, nucleic acids, lipids, and many other compounds. Carbon accounts for about 50 percent of the composition of the cell. Nitrogen represents 12 percent of the total dry weight of a typical cell and is a component of proteins, nucleic acids, and other cell constituents. Most of the nitrogen available in nature is either atmospheric nitrogen (N 2 ) or another inorganic form. Diatomic (N 2 ) nitrogen, however, can be converted into an organic form only by certain organisms, called nitrogen-fixing organisms. Both hydrogen and oxygen are part of many organic compounds and of water. Phosphorus is required by all organisms for the synthesis of nucleotides and phospholipids. Sulfur is part of the structure of some amino acids such as cysteine and methionine, and is also present in several vitamins and coenzymes. Other important macronutrients are potassium (K), magnesium (Mg), calcium (Ca), and sodium (Na). Although these elements are required in smaller amounts, they are very important for the structure and function of the prokaryotic cell. Micronutrients In addition to these macronutrients, prokaryotes require various metallic elements in small amounts. These are referred to as micronutrients or trace elements. For example, iron is necessary for the function of the cytochromes involved in electron-transport reactions. Some prokaryotes require other elements—such as boron (B), chromium (Cr), and manganese (Mn)—primarily as enzyme cofactors. The Ways in Which Prokaryotes Obtain Energy Prokaryotes can use different sources of energy to assemble macromolecules from smaller molecules. Phototrophs (or phototrophic organisms) obtain their energy from sunlight. Chemotrophs (or chemosynthetic organisms) obtain their energy from chemical compounds. Chemotrophs that can use organic compounds as energy sources are called chemoorganotrophs. Those that can also use inorganic compounds as energy sources are called chemolitotrophs. The Ways in Which Prokaryotes Obtain Carbon Prokaryotes not only can use different sources of energy but also different sources of carbon compounds. Recall that organisms that are able to fix inorganic carbon are called autotrophs. Autotrophic prokaryotes synthesize organic molecules from carbon dioxide. In contrast, heterotrophic prokaryotes obtain carbon from organic compounds. To make the picture more complex, the terms that describe how prokaryotes obtain energy and carbon can be combined. Thus, photoautotrophs use energy from sunlight, and carbon from carbon dioxide and water, whereas chemoheterotrophs obtain energy and carbon from an organic chemical source. Chemolitoautotrophs obtain their energy from inorganic compounds, and they build their complex molecules from carbon dioxide. The table below ( Table 22.3 ) summarizes carbon and energy sources in prokaryotes. Carbon and Energy Sources in Prokaryotes Energy Sources Carbon Sources Light Chemicals Carbon dioxide Organic compounds Phototrophs Chemotrophs Autotrophs Heterotrophs Organic chemicals Inorganic chemicals Chemo-organotrophs Chemolithotrophs Table 22.3 Role of Prokaryotes in Ecosystems Prokaryotes are ubiquitous: There is no niche or ecosystem in which they are not present. Prokaryotes play many roles in the environments they occupy. The roles they play in the carbon and nitrogen cycles are vital to life on Earth. Prokaryotes and the Carbon Cycle Carbon is one of the most important macronutrients, and prokaryotes play an important role in the carbon cycle ( Figure 22.18 ). Carbon is cycled through Earth’s major reservoirs: land, the atmosphere, aquatic environments, sediments and rocks, and biomass. The movement of carbon is via carbon dioxide, which is removed from the atmosphere by land plants and marine prokaryotes, and is returned to the atmosphere via the respiration of chemoorganotrophic organisms, including prokaryotes, fungi, and animals. Although the largest carbon reservoir in terrestrial ecosystems is in rocks and sediments, that carbon is not readily available. A large amount of available carbon is found in land plants. Plants, which are producers, use carbon dioxide from the air to synthesize carbon compounds. Related to this, one very significant source of carbon compounds is humus, which is a mixture of organic materials from dead plants and prokaryotes that have resisted decomposition. Consumers such as animals use organic compounds generated by producers and release carbon dioxide to the atmosphere. Then, bacteria and fungi, collectively called decomposers , carry out the breakdown (decomposition) of plants and animals and their organic compounds. The most important contributor of carbon dioxide to the atmosphere is microbial decomposition of dead material (dead animals, plants, and humus) that undergo respiration. In aqueous environments and their anoxic sediments, there is another carbon cycle taking place. In this case, the cycle is based on one-carbon compounds. In anoxic sediments, prokaryotes, mostly archaea, produce methane (CH 4 ). This methane moves into the zone above the sediment, which is richer in oxygen and supports bacteria called methane oxidizers that oxidize methane to carbon dioxide, which then returns to the atmosphere. Prokaryotes and the Nitrogen Cycle Nitrogen is a very important element for life because it is part of proteins and nucleic acids. It is a macronutrient, and in nature, it is recycled from organic compounds to ammonia, ammonium ions, nitrate, nitrite, and nitrogen gas by myriad processes, many of which are carried out only by prokaryotes. As illustrated in Figure 22.19 , prokaryotes are key to the nitrogen cycle. The largest pool of nitrogen available in the terrestrial ecosystem is gaseous nitrogen from the air, but this nitrogen is not usable by plants, which are primary producers. Gaseous nitrogen is transformed, or “fixed” into more readily available forms such as ammonia through the process of nitrogen fixation . Ammonia can be used by plants or converted to other forms. Another source of ammonia is ammonification , the process by which ammonia is released during the decomposition of nitrogen-containing organic compounds. Ammonia released to the atmosphere, however, represents only 15 percent of the total nitrogen released; the rest is as N 2 and N 2 O. Ammonia is catabolized anaerobically by some prokaryotes, yielding N 2 as the final product. Nitrification is the conversion of ammonium to nitrite and nitrate. Nitrification in soils is carried out by bacteria belonging to the genera Nitrosomas , Nitrobacter , and Nitrospira . The bacteria performs the reverse process, the reduction of nitrate from the soils to gaseous compounds such as N 2 O, NO, and N 2 , a process called denitrification . Visual Connection Which of the following statements about the nitrogen cycle is false? Nitrogen fixing bacteria exist on the root nodules of legumes and in the soil. Denitrifying bacteria convert nitrates (NO 3 - ) into nitrogen gas (N 2 ). Ammonification is the process by which ammonium ion (NH 4 + ) is released from decomposing organic compounds. Nitrification is the process by which nitrites (NO 2 - ) are converted to ammonium ion (NH 4 + ). 22.4 Bacterial Diseases in Humans Learning Objectives By the end of this section, you will be able to: Identify bacterial diseases that caused historically important plagues and epidemics Describe the link between biofilms and foodborne diseases Explain how overuse of antibiotic may be creating “super bugs” Explain the importance of MRSA with respect to the problems of antibiotic resistance Devastating pathogen-borne diseases and plagues, both viral and bacterial in nature, have affected humans since the beginning of human history. The true cause of these diseases was not understood at the time, and some people thought that diseases were a spiritual punishment. Over time, people came to realize that staying apart from afflicted persons, and disposing of the corpses and personal belongings of victims of illness, reduced their own chances of getting sick. Epidemiologists study how diseases affect a population. An epidemic is a disease that occurs in an unusually high number of individuals in a population at the same time. A pandemic is a widespread, usually worldwide, epidemic. An endemic disease is a disease that is constantly present, usually at low incidence, in a population. Long History of Bacterial Disease There are records about infectious diseases as far back as 3000 B.C. A number of significant pandemics caused by bacteria have been documented over several hundred years. Some of the most memorable pandemics led to the decline of cities and nations. In the 21 st century, infectious diseases remain among the leading causes of death worldwide, despite advances made in medical research and treatments in recent decades. A disease spreads when the pathogen that causes it is passed from one person to another. For a pathogen to cause disease, it must be able to reproduce in the host’s body and damage the host in some way. The Plague of Athens In 430 B.C., the Plague of Athens killed one-quarter of the Athenian troops that were fighting in the great Peloponnesian War and weakened Athens’ dominance and power. The plague impacted people living in overcrowded Athens as well as troops aboard ships that had to return to Athens. The source of the plague may have been identified recently when researchers from the University of Athens were able to use DNA from teeth recovered from a mass grave. The scientists identified nucleotide sequences from a pathogenic bacterium, Salmonella enterica serovar Typhi ( Figure 22.20 ), which causes typhoid fever. 3 This disease is commonly seen in overcrowded areas and has caused epidemics throughout recorded history. 3 Papagrigorakis MJ , Synodinos PN , and Yapijakis C . Ancient typhoid epidemic reveals possible ancestral strain of Salmonella enterica serovar Typhi. Infect Genet Evol 7 (2007): 126–7, Epub 2006 Jun. Bubonic Plagues From 541 to 750, an outbreak of what was likely a bubonic plague (the Plague of Justinian), eliminated one-quarter to one-half of the human population in the eastern Mediterranean region. The population in Europe dropped by 50 percent during this outbreak. Bubonic plague would strike Europe more than once. One of the most devastating pandemics was the Black Death (1346 to 1361) that is believed to have been another outbreak of bubonic plague caused by the bacterium Yersinia pestis . It is thought to have originated initially in China and spread along the Silk Road, a network of land and sea trade routes, to the Mediterranean region and Europe, carried by rat fleas living on black rats that were always present on ships. The Black Death reduced the world’s population from an estimated 450 million to about 350 to 375 million. Bubonic plague struck London hard again in the mid-1600s ( Figure 22.21 ). In modern times, approximately 1,000 to 3,000 cases of plague arise globally each year. Although contracting bubonic plague before antibiotics meant almost certain death, the bacterium responds to several types of modern antibiotics, and mortality rates from plague are now very low. Link to Learning Watch a video on the modern understanding of the Black Death—bubonic plague in Europe during the 14 th century. Migration of Diseases to New Populations Over the centuries, Europeans tended to develop genetic immunity to endemic infectious diseases, but when European conquerors reached the western hemisphere, they brought with them disease-causing bacteria and viruses, which triggered epidemics that completely devastated populations of Native Americans, who had no natural resistance to many European diseases. It has been estimated that up to 90 percent of Native Americans died from infectious diseases after the arrival of Europeans, making conquest of the New World a foregone conclusion. Emerging and Re-emerging Diseases The distribution of a particular disease is dynamic. Therefore, changes in the environment, the pathogen, or the host population can dramatically impact the spread of a disease. According to the World Health Organization (WHO) an emerging disease ( Figure 22.22 ) is one that has appeared in a population for the first time, or that may have existed previously but is rapidly increasing in incidence or geographic range. This definition also includes re-emerging diseases that were previously under control. Approximately 75 percent of recently emerging infectious diseases affecting humans are zoonotic diseases, zoonoses , diseases that primarily infect animals and are transmitted to humans; some are of viral origin and some are of bacterial origin. Brucellosis is an example of a prokaryotic zoonosis that is re-emerging in some regions, and necrotizing fasciitis (commonly known as flesh-eating bacteria) has been increasing in virulence for the last 80 years for unknown reasons. Some of the present emerging diseases are not actually new, but are diseases that were catastrophic in the past ( Figure 22.23 ). They devastated populations and became dormant for a while, just to come back, sometimes more virulent than before, as was the case with bubonic plague. Other diseases, like tuberculosis, were never eradicated but were under control in some regions of the world until coming back, mostly in urban centers with high concentrations of immunocompromised people. The WHO has identified certain diseases whose worldwide re-emergence should be monitored. Among these are two viral diseases (dengue fever and yellow fever), and three bacterial diseases (diphtheria, cholera, and bubonic plague). The war against infectious diseases has no foreseeable end. Biofilms and Disease Recall that biofilms are microbial communities that are very difficult to destroy. They are responsible for diseases such as infections in patients with cystic fibrosis, Legionnaires’ disease, and otitis media. They produce dental plaque and colonize catheters, prostheses, transcutaneous and orthopedic devices, contact lenses, and internal devices such as pacemakers. They also form in open wounds and burned tissue. In healthcare environments, biofilms grow on hemodialysis machines, mechanical ventilators, shunts, and other medical equipment. In fact, 65 percent of all infections acquired in the hospital (nosocomial infections) are attributed to biofilms. Biofilms are also related to diseases contracted from food because they colonize the surfaces of vegetable leaves and meat, as well as food-processing equipment that isn’t adequately cleaned. Biofilm infections develop gradually; sometimes, they do not cause symptoms immediately. They are rarely resolved by host defense mechanisms. Once an infection by a biofilm is established, it is very difficult to eradicate, because biofilms tend to be resistant to most of the methods used to control microbial growth, including antibiotics. Biofilms respond poorly or only temporarily to antibiotics; it has been said that they can resist up to 1,000 times the antibiotic concentrations used to kill the same bacteria when they are free-living or planktonic. An antibiotic dose that large would harm the patient; therefore, scientists are working on new ways to get rid of biofilms. Antibiotics: Are We Facing a Crisis? The word antibiotic comes from the Greek anti meaning “against” and bios meaning “life.” An antibiotic is a chemical, produced either by microbes or synthetically, that is hostile to the growth of other organisms. Today’s news and media often address concerns about an antibiotic crisis. Are the antibiotics that easily treated bacterial infections in the past becoming obsolete? Are there new “superbugs”—bacteria that have evolved to become more resistant to our arsenal of antibiotics? Is this the beginning of the end of antibiotics? All these questions challenge the healthcare community. One of the main causes of resistant bacteria is the abuse of antibiotics. The imprudent and excessive use of antibiotics has resulted in the natural selection of resistant forms of bacteria. The antibiotic kills most of the infecting bacteria, and therefore only the resistant forms remain. These resistant forms reproduce, resulting in an increase in the proportion of resistant forms over non-resistant ones. Another major misuse of antibiotics is in patients with colds or the flu, for which antibiotics are useless. Another problem is the excessive use of antibiotics in livestock. The routine use of antibiotics in animal feed promotes bacterial resistance as well. In the United States, 70 percent of the antibiotics produced are fed to animals. These antibiotics are given to livestock in low doses, which maximize the probability of resistance developing, and these resistant bacteria are readily transferred to humans. Link to Learning Watch a recent news report on the problem of routine antibiotic administration to livestock and antibiotic-resistant bacteria. One of the Superbugs: MRSA The imprudent use of antibiotics has paved the way for bacteria to expand populations of resistant forms. For example, Staphylococcus aureu s, often called “staph,” is a common bacterium that can live in the human body and is usually easily treated with antibiotics. A very dangerous strain, however, methicillin-resistant Staphylococcus aureus (MRSA) has made the news over the past few years ( Figure 22.24 ). This strain is resistant to many commonly used antibiotics, including methicillin, amoxicillin, penicillin, and oxacillin. MRSA can cause infections of the skin, but it can also infect the bloodstream, lungs, urinary tract, or sites of injury. While MRSA infections are common among people in healthcare facilities, they have also appeared in healthy people who haven’t been hospitalized but who live or work in tight populations (like military personnel and prisoners). Researchers have expressed concern about the way this latter source of MRSA targets a much younger population than those residing in care facilities. The Journal of the American Medical Association reported that, among MRSA-afflicted persons in healthcare facilities, the average age is 68, whereas people with “community-associated MRSA” ( CA-MRSA ) have an average age of 23. 4 4 Naimi, TS, LeDell, KH, Como-Sabetti, K, et al. Comparison of community- and health care-associated methicillin-resistant Staphylococcus aureus infection. JAMA 290 (2003): 2976–84, doi: 10.1001/jama.290.22.2976 . In summary, the medical community is facing an antibiotic crisis. Some scientists believe that after years of being protected from bacterial infections by antibiotics, we may be returning to a time in which a simple bacterial infection could again devastate the human population. Researchers are developing new antibiotics, but it takes many years to of research and clinical trials, plus financial investments in the millions of dollars, to generate an effective and approved drug. Foodborne Diseases Prokaryotes are everywhere: They readily colonize the surface of any type of material, and food is not an exception. Most of the time, prokaryotes colonize food and food-processing equipment in the form of a biofilm. Outbreaks of bacterial infection related to food consumption are common. A foodborne disease (colloquially called “food poisoning”) is an illness resulting from the consumption the pathogenic bacteria, viruses, or other parasites that contaminate food. Although the United States has one of the safest food supplies in the world, the U.S. Centers for Disease Control and Prevention (CDC) has reported that “76 million people get sick, more than 300,000 are hospitalized, and 5,000 Americans die each year from foodborne illness.” The characteristics of foodborne illnesses have changed over time. In the past, it was relatively common to hear about sporadic cases of botulism , the potentially fatal disease produced by a toxin from the anaerobic bacterium Clostridium botulinum . Some of the most common sources for this bacterium were non-acidic canned foods, homemade pickles, and processed meat and sausages. The can, jar, or package created a suitable anaerobic environment where Clostridium could grow. Proper sterilization and canning procedures have reduced the incidence of this disease. While people may tend to think of foodborne illnesses as associated with animal-based foods, most cases are now linked to produce. There have been serious, produce-related outbreaks associated with raw spinach in the United States and with vegetable sprouts in Germany, and these types of outbreaks have become more common. The raw spinach outbreak in 2006 was produced by the bacterium E. coli serotype O157:H7. A serotype is a strain of bacteria that carries a set of similar antigens on its cell surface, and there are often many different serotypes of a bacterial species. Most E. coli are not particularly dangerous to humans, but serotype O157:H7 can cause bloody diarrhea and is potentially fatal. All types of food can potentially be contaminated with bacteria. Recent outbreaks of Salmonella reported by the CDC occurred in foods as diverse as peanut butter, alfalfa sprouts, and eggs. A deadly outbreak in Germany in 2010 was caused by E. coli contamination of vegetable sprouts ( Figure 22.25 ). The strain that caused the outbreak was found to be a new serotype not previously involved in other outbreaks, which indicates that E. coli is continuously evolving. Career Connection Epidemiologist Epidemiology is the study of the occurrence, distribution, and determinants of health and disease in a population. It is, therefore, part of public health. An epidemiologist studies the frequency and distribution of diseases within human populations and environments. Epidemiologists collect data about a particular disease and track its spread to identify the original mode of transmission. They sometimes work in close collaboration with historians to try to understand the way a disease evolved geographically and over time, tracking the natural history of pathogens. They gather information from clinical records, patient interviews, surveillance, and any other available means. That information is used to develop strategies, such as vaccinations ( Figure 22.26 ), and design public health policies to reduce the incidence of a disease or to prevent its spread. Epidemiologists also conduct rapid investigations in case of an outbreak to recommend immediate measures to control it. An epidemiologist has a bachelor’s degree, plus a master’s degree in public health (MPH). Many epidemiologists are also physicians (and have an M.D.), or they have a Ph.D. in an associated field, such as biology or microbiology. 22.5 Beneficial Prokaryotes Learning Objectives By the end of this section, you will be able to: Explain the need for nitrogen fixation and how it is accomplished Identify foods in which prokaryotes are used in the processing Describe the use of prokaryotes in bioremediation Describe the beneficial effects of bacteria that colonize our skin and digestive tracts Not all prokaryotes are pathogenic. On the contrary, pathogens represent only a very small percentage of the diversity of the microbial world. In fact, our life would not be possible without prokaryotes. Just think about the role of prokaryotes in biogeochemical cycles. Cooperation between Bacteria and Eukaryotes: Nitrogen Fixation Nitrogen is a very important element to living things, because it is part of nucleotides and amino acids that are the building blocks of nucleic acids and proteins, respectively. Nitrogen is usually the most limiting element in terrestrial ecosystems, with atmospheric nitrogen, N 2 , providing the largest pool of available nitrogen. However, eukaryotes cannot use atmospheric, gaseous nitrogen to synthesize macromolecules. Fortunately, nitrogen can be “fixed,” meaning it is converted into ammonia (NH 3 ) either biologically or abiotically. Abiotic nitrogen fixation occurs as a result of lightning or by industrial processes. Biological nitrogen fixation (BNF) is exclusively carried out by prokaryotes: soil bacteria, cyanobacteria, and Frankia spp. (filamentous bacteria interacting with actinorhizal plants such as alder, bayberry, and sweet fern). After photosynthesis, BNF is the second most important biological process on Earth. The equation representing the process is as follows N 2  + 16ATP + 8e −  + 8H +   →  2NH 3  + 16ADP + 16Pi + H 2 N 2  + 16ATP + 8e −  + 8H +   →  2NH 3  + 16ADP + 16Pi + H 2 where Pi stands for inorganic phosphate. The total fixed nitrogen through BNF is about 100 to 180 million metric tons per year. Biological processes contribute 65 percent of the nitrogen used in agriculture. Cyanobacteria are the most important nitrogen fixers in aquatic environments. In soil, members of the genus Clostridium are examples of free-living, nitrogen-fixing bacteria. Other bacteria live symbiotically with legume plants, providing the most important source of BNF. Symbionts may fix more nitrogen in soils than free-living organisms by a factor of 10. Soil bacteria, collectively called rhizobia, are able to symbiotically interact with legumes to form nodules , specialized structures where nitrogen fixation occurs ( Figure 22.27 ). Nitrogenase, the enzyme that fixes nitrogen, is inactivated by oxygen, so the nodule provides an oxygen-free area for nitrogen fixation to take place. This process provides a natural and inexpensive plant fertilizer, as it reduces atmospheric nitrogen to ammonia, which is easily usable by plants. The use of legumes is an excellent alternative to chemical fertilization and is of special interest to sustainable agriculture, which seeks to minimize the use of chemicals and conserve natural resources. Through symbiotic nitrogen fixation, the plant benefits from using an endless source of nitrogen: the atmosphere. Bacteria benefit from using photosynthates (carbohydrates produced during photosynthesis) from the plant and having a protected niche. Additionally, the soil benefits from being naturally fertilized. Therefore, the use of rhizobia as biofertilizers is a sustainable practice. Why are legumes so important? Some, like soybeans, are key sources of agricultural protein. Some of the most important grain legumes are soybean, peanuts, peas, chickpeas, and beans. Other legumes, such as alfalfa, are used to feed cattle. Early Biotechnology: Cheese, Bread, Wine, Beer, and Yogurt According to the United Nations Convention on Biological Diversity, biotechnology is “any technological application that uses biological systems, living organisms, or derivatives thereof, to make or modify products or processes for specific use." 5 The concept of “specific use” involves some sort of commercial application. Genetic engineering, artificial selection, antibiotic production, and cell culture are current topics of study in biotechnology. However, humans have used prokaryotes before the term biotechnology was even coined. In addition, some of the goods and services are as simple as cheese, bread, wine, beer, and yogurt, which employ both bacteria and other microbes, such as yeast, a fungus ( Figure 22.28 ). 5 http://www.cbd.int/convention/articles/?a=cbd-02, United Nations Convention on Biological Diversity: Article 2: Use of Terms. Cheese production began around 4,000–7,000 years ago when humans began to breed animals and process their milk. Fermentation in this case preserves nutrients: Milk will spoil relatively quickly, but when processed as cheese, it is more stable. As for beer, the oldest records of brewing are about 6,000 years old and refer to the Sumerians. Evidence indicates that the Sumerians discovered fermentation by chance. Wine has been produced for about 4,500 years, and evidence suggests that cultured milk products, like yogurt, have existed for at least 4,000 years. Using Prokaryotes to Clean up Our Planet: Bioremediation Microbial bioremediation is the use of prokaryotes (or microbial metabolism) to remove pollutants. Bioremediation has been used to remove agricultural chemicals (pesticides, fertilizers) that leach from soil into groundwater and the subsurface. Certain toxic metals and oxides, such as selenium and arsenic compounds, can also be removed from water by bioremediation. The reduction of SeO 4 -2 to SeO 3 -2 and to Se 0 (metallic selenium) is a method used to remove selenium ions from water. Mercury is an example of a toxic metal that can be removed from an environment by bioremediation. As an active ingredient of some pesticides, mercury is used in industry and is also a by-product of certain processes, such as battery production. Methyl mercury is usually present in very low concentrations in natural environments, but it is highly toxic because it accumulates in living tissues. Several species of bacteria can carry out the biotransformation of toxic mercury into nontoxic forms. These bacteria, such as Pseudomonas aeruginosa , can convert Hg +2 into Hg 0 , which is nontoxic to humans. One of the most useful and interesting examples of the use of prokaryotes for bioremediation purposes is the cleanup of oil spills. The importance of prokaryotes to petroleum bioremediation has been demonstrated in several oil spills in recent years, such as the Exxon Valdez spill in Alaska (1989) ( Figure 22.29 ), the Prestige oil spill in Spain (2002), the spill into the Mediterranean from a Lebanon power plant (2006), and more recently, the BP oil spill in the Gulf of Mexico (2010). To clean up these spills, bioremediation is promoted by the addition of inorganic nutrients that help bacteria to grow. Hydrocarbon-degrading bacteria feed on hydrocarbons in the oil droplet, breaking down the hydrocarbons. Some species, such as Alcanivorax borkumensis , produce surfactants that solubilize the oil, whereas other bacteria degrade the oil into carbon dioxide. In the case of oil spills in the ocean, ongoing, natural bioremediation tends to occur, inasmuch as there are oil-consuming bacteria in the ocean prior to the spill. In addition to naturally occurring oil-degrading bacteria, humans select and engineer bacteria that possess the same capability with increased efficacy and spectrum of hydrocarbon compounds that can be processed. Under ideal conditions, it has been reported that up to 80 percent of the nonvolatile components in oil can be degraded within one year of the spill. Other oil fractions containing aromatic and highly branched hydrocarbon chains are more difficult to remove and remain in the environment for longer periods of time. Everyday Connection Microbes on the Human Body The commensal bacteria that inhabit our skin and gastrointestinal tract do a host of good things for us. They protect us from pathogens, help us digest our food, and produce some of our vitamins and other nutrients. These activities have been known for a long time. More recently, scientists have gathered evidence that these bacteria may also help regulate our moods, influence our activity levels, and even help control weight by affecting our food choices and absorption patterns. The Human Microbiome Project has begun the process of cataloging our normal bacteria (and archaea) so we can better understand these functions. A particularly fascinating example of our normal flora relates to our digestive systems. People who take high doses of antibiotics tend to lose many of their normal gut bacteria, allowing a naturally antibiotic-resistant species called Clostridium difficile to overgrow and cause severe gastric problems, especially chronic diarrhea ( Figure 22.30 ). Obviously, trying to treat this problem with antibiotics only makes it worse. However, it has been successfully treated by giving the patients fecal transplants from healthy donors to reestablish the normal intestinal microbial community. Clinical trials are underway to ensure the safety and effectiveness of this technique. Scientists are also discovering that the absence of certain key microbes from our intestinal tract may set us up for a variety of problems. This seems to be particularly true regarding the appropriate functioning of the immune system. There are intriguing findings that suggest that the absence of these microbes is an important contributor to the development of allergies and some autoimmune disorders. Research is currently underway to test whether adding certain microbes to our internal ecosystem may help in the treatment of these problems as well as in treating some forms of autism.
principles_of_accounting,_volume_2:_managerial_accounting
Summary 3.1 Explain Contribution Margin and Calculate Contribution Margin per Unit, Contribution Margin Ratio, and Total Contribution Margin Contribution margin can be used to calculate how much of every dollar in sales is available to cover fixed expenses and contribute to profit. Contribution margin can be expressed on a per-unit basis, as a ratio, or in total. A specialized income statement, the Contribution Margin Income Statement, can be useful in looking at total sales and total contribution margin at varying levels of activity. 3.2 Calculate a Break-Even Point in Units and Dollars Break-even analysis is a tool that almost any business can use for planning and evaluation purposes. It helps identify a level of activity that is necessary before an organization starts to generate a profit. A break-even point can be found on a per-unit basis or as a dollar amount, depending upon whether a per-unit contribution margin or a contribution margin ratio is applied. 3.3 Perform Break-Even Sensitivity Analysis for a Single Product Under Changing Business Situations Cost-volume-profit analysis can be used to conduct a sensitivity analysis that shows what will happen if there are changes in any of the variables: sales price, units sold, variable cost per unit, or fixed costs. The break-even point may or may not be impacted by changes in costs depending on the type of cost affected. 3.4 Perform Break-Even Sensitivity Analysis for a Multi-Product Environment Under Changing Business Situations Companies provide multiple products, goods, and services to the consumer and, as result, need to calculate their break-even point based on the mix of the products, goods, and services. In a multi-product environment, calculating the break-even point is more complex and is usually calculated using a composite unit, which represents the sales mix of the business. If the sales mix of a company changes, then the break-even point changes, regardless of whether total sales dollars change or not. 3.5 Calculate and Interpret a Company’s Margin of Safety and Operating Leverage Businesses determine a margin of safety (sales dollars beyond the break-even point). The higher the margin of safety is, the lower the risk is of not breaking even and incurring a loss. Operating leverage is a measurement of how sensitive net operating income is to a percentage change in sales dollars. A high degree of operating leverage results from a cost structure that is heavily weighted in fixed costs.
Chapter Outline 3.1 Explain Contribution Margin and Calculate Contribution Margin per Unit, Contribution Margin Ratio, and Total Contribution Margin 3.2 Calculate a Break-Even Point in Units and Dollars 3.3 Perform Break-Even Sensitivity Analysis for a Single Product Under Changing Business Situations 3.4 Perform Break-Even Sensitivity Analysis for a Multi-Product Environment Under Changing Business Situations 3.5 Calculate and Interpret a Company’s Margin of Safety and Operating Leverage Why It Matters As president of the Accounting Club, you are working on a fundraiser selling T-shirts on campus. You have gotten quotes from several suppliers ranging from $8 to $10 per shirt and now have to select a vendor. The prices vary based on whether the T-shirts have pockets, have long sleeves or short sleeves, and are printed on one side or both. You are confident that you can sell them for $15 each. However, the college charges clubs a $100 “student sale” fee, and your T-shirt sales must cover this cost and still net the club enough money to pay for your spring trip In addition, several of the vendors will give volume discounts—the more shirts you purchase, the less each shirt costs. In short, you need to know exactly which style of T-shirt, vendor, and quantity will allow you to reach your desired net income and cover your fixed expense of $100. You decide on a short-sleeve shirt with a pocket that costs $10 each and that you can sell for $15. This $5 per shirt “gross profit” will first go toward covering the $100 student sale fee. That means you will have to sell 20 shirts to pay the fee ($100/$5 = 20 shirts). After selling the first 20 shirts, the $5 profit will be available to start paying for the cost of the trip. Your faculty advisor has calculated that the trip will cost $125 per student, and you have 6 people signed up for the trip. This means the sale will need to generate an additional $750 from the sale (6 students × $125). At $5 per shirt you will need to sell 150 shirts to cover the student costs ($750/$5). So, you will need to sell a total of 170 shirts: 20 to cover your fixed cost of $100 and an additional 150 to cover the student’s cost of the trip ($750). What you have just completed is a cost-volume-profit analysis. In this chapter, we will explore how managers can use this type of analysis to make a wide range of decisions about their business operations.
[ { "answer": { "ans_choice": 0, "ans_text": "A" }, "bloom": null, "hl_context": "<hl> The contribution margin ratio is the percentage of a unit ’ s selling price that exceeds total unit variable costs . <hl> In other words , contribution margin is expressed as a percentage of sales price and is calculated using this formula : <hl> Contribution margin is the amount by which a product ’ s selling price exceeds its total variable cost per unit . <hl> This difference between the sales price and the per unit variable cost is called the contribution margin because it is the per unit contribution toward covering the fixed costs . It typically is calculated by comparing the sales revenue generated by the sale of one item versus the variable cost of the item :", "hl_sentences": "The contribution margin ratio is the percentage of a unit ’ s selling price that exceeds total unit variable costs . Contribution margin is the amount by which a product ’ s selling price exceeds its total variable cost per unit .", "question": { "cloze_format": "The amount of a unit’s sales price that helps to cover fixed expenses is its ________.", "normal_format": "Which amount of a unit’s sales price helps to cover fixed expenses?", "question_choices": [ "contribution margin", "profit", "variable cost", "stepped cost" ], "question_id": "fs-idm189575152", "question_text": "The amount of a unit’s sales price that helps to cover fixed expenses is its ________." }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 2, "ans_text": "decrease" }, "bloom": null, "hl_context": "<hl> The analysis shows the expected result : an increase in the per-unit contribution margin , a decrease in the break-even point , and an increase in the net operating income . <hl> She has changed three variables in her costs — sales price , variable cost , and fixed cost . In fact , the small price increase almost gets her back to the net operating income she realized before the purchase of the new expresso machine .", "hl_sentences": "The analysis shows the expected result : an increase in the per-unit contribution margin , a decrease in the break-even point , and an increase in the net operating income .", "question": { "cloze_format": "When sales price increases and all other variables are held constant, the break-even point will ________.", "normal_format": "How will the break-even point perform when sales price increases and all other variables are held constant?", "question_choices": [ "remain unchanged", "increase", "decrease", "produce a lower contribution margin" ], "question_id": "fs-idm238534608", "question_text": "When sales price increases and all other variables are held constant, the break-even point will ________." }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 1, "ans_text": "B" }, "bloom": null, "hl_context": "When a company sells more than one product or provides more than one service , break-even analysis is more complex because not all of the products sell for the same price or have the same costs associated with them : Each product has its own margin . Consequently , the break-even point in a multi-product environment depends on the mix of products sold . Further , when the mix of products changes , so does the break-even point . <hl> If demand shifts and customers purchase more low-margin products , then the break-even point rises . <hl> Conversely , if customers purchase more high-margin products , the break-even point falls . In fact , even if total sales dollars remain unchanged , the break-even point can change based on the sales mix . Let ’ s look at an example of how break-even analysis works in a multi-product environment .", "hl_sentences": "If demand shifts and customers purchase more low-margin products , then the break-even point rises .", "question": { "cloze_format": "When sales price decreases and all other variables are held constant, the break-even point will ________.", "normal_format": "How will the break-even point perform when sales price decreases and all other variables are held constant?", "question_choices": [ "remain unchanged", "increase", "decrease", "produce a higher contribution margin" ], "question_id": "fs-idm222724000", "question_text": "When sales price decreases and all other variables are held constant, the break-even point will ________." }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 1, "ans_text": "increase" }, "bloom": null, "hl_context": "<hl> Break-Even Point Increases ( Contribution Margin is Lower , Need More Sales to Break Even ) <hl> <hl> Variable Costs Increase <hl>", "hl_sentences": "Break-Even Point Increases ( Contribution Margin is Lower , Need More Sales to Break Even ) Variable Costs Increase", "question": { "cloze_format": "When variable costs increase and all other variables remain unchanged, the break-even point will ________.", "normal_format": "How will the break-even point perform when variable costs increase and all other variables remain unchanged?", "question_choices": [ "remain unchanged", "increase", "decrease", "produce a lower contribution margin" ], "question_id": "fs-idm242215072", "question_text": "When variable costs increase and all other variables remain unchanged, the break-even point will ________." }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 2, "ans_text": "C" }, "bloom": null, "hl_context": "<hl> Break-Even Point Decreases ( Contribution Margin Does Not Change , but Need Fewer Sales to Meet Fixed Costs ) <hl> <hl> Fixed Costs Decrease <hl>", "hl_sentences": "Break-Even Point Decreases ( Contribution Margin Does Not Change , but Need Fewer Sales to Meet Fixed Costs ) Fixed Costs Decrease", "question": { "cloze_format": "When fixed costs decrease and all other variables remain unchanged, the break-even point will ________.", "normal_format": "When fixed costs decrease and all other variables remain unchanged, what will the break-even point do?", "question_choices": [ "remain unchanged", "increase", "decrease", "produce a lower contribution margin" ], "question_id": "fs-idm246893536", "question_text": "When fixed costs decrease and all other variables remain unchanged, the break-even point will ________." }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 2, "ans_text": "decrease" }, "bloom": null, "hl_context": "<hl> Because the rent increase is a change in a fixed cost , the contribution margin per unit remains the same . <hl> However , the break-even point in both units and dollars increase because more units of contribution are needed to cover the $ 225 monthly increase in fixed costs . If the owner of the Back Door agrees to the increase in rent for the new lease , she will likely look for ways to increase the contribution margin per unit to offset this increase in fixed costs .", "hl_sentences": "Because the rent increase is a change in a fixed cost , the contribution margin per unit remains the same .", "question": { "cloze_format": "When fixed costs increase and all other variables remain unchanged, the contribution margin will ________.", "normal_format": "When fixed costs increase and all other variables remain unchanged, what will the contribution margin do?", "question_choices": [ "remain unchanged", "increase", "decrease", "increase variable costs per unit" ], "question_id": "fs-idm218692112", "question_text": "When fixed costs increase and all other variables remain unchanged, the contribution margin will ________." }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 2, "ans_text": "C" }, "bloom": null, "hl_context": "When a company sells more than one product or provides more than one service , break-even analysis is more complex because not all of the products sell for the same price or have the same costs associated with them : Each product has its own margin . Consequently , the break-even point in a multi-product environment depends on the mix of products sold . Further , when the mix of products changes , so does the break-even point . <hl> If demand shifts and customers purchase more low-margin products , then the break-even point rises . <hl> <hl> Conversely , if customers purchase more high-margin products , the break-even point falls . <hl> In fact , even if total sales dollars remain unchanged , the break-even point can change based on the sales mix . Let ’ s look at an example of how break-even analysis works in a multi-product environment .", "hl_sentences": "If demand shifts and customers purchase more low-margin products , then the break-even point rises . Conversely , if customers purchase more high-margin products , the break-even point falls .", "question": { "cloze_format": "If the sales mix in a multi-product environment shifts to a higher volume in low contribution margin products, the break-even point will ________.", "normal_format": "If the sales mix in a multi-product environment shifts to a higher volume in low contribution margin products, what will the break-even point do?", "question_choices": [ "remain unchanged because all products are included in the calculation of break-even", "increase because the low contribution margin products have little effect on break-even", "increase because the per composite unit contribution margin will decrease", "decrease because the per composite unit contribution margin will increase" ], "question_id": "fs-idm235160704", "question_text": "If the sales mix in a multi-product environment shifts to a higher volume in low contribution margin products, the break-even point will ________." }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 0, "ans_text": "can be calculated by dividing total fixed costs by the contribution margin of a composite unit" }, "bloom": null, "hl_context": "<hl> Break-Even Point per Composite Unit = Total fixed costs Contribution margin per composite unit = $ 145,000 $ 30.75 = 4,715 . 45 composite units Break-Even Point per Composite Unit = Total fixed costs Contribution margin per composite unit = $ 145,000 $ 30.75 = 4,715 . 45 composite units <hl> <hl> Break-Even Point in Units = Total fixed costs Contribution margin per unit = $ 14,000 $ 250 = 56 returns Break-Even Point in Units = Total fixed costs Contribution margin per unit = $ 14,000 $ 250 = 56 returns <hl>", "hl_sentences": "Break-Even Point per Composite Unit = Total fixed costs Contribution margin per composite unit = $ 145,000 $ 30.75 = 4,715 . 45 composite units Break-Even Point per Composite Unit = Total fixed costs Contribution margin per composite unit = $ 145,000 $ 30.75 = 4,715 . 45 composite units Break-Even Point in Units = Total fixed costs Contribution margin per unit = $ 14,000 $ 250 = 56 returns Break-Even Point in Units = Total fixed costs Contribution margin per unit = $ 14,000 $ 250 = 56 returns", "question": { "cloze_format": "Break-even for a multiple product firm ________.", "normal_format": "Which of the following is correct about a break-even for a multiple product firm?", "question_choices": [ "can be calculated by dividing total fixed costs by the contribution margin of a composite unit", "can be calculated by multiplying fixed costs by the contribution margin ratio of a composite unit", "can only be calculated when the proportion of products sold is the same for all products", "can be calculated by multiplying fixed costs by the contribution margin ratio of the most common product in the sales mix" ], "question_id": "fs-idm236428528", "question_text": "Break-even for a multiple product firm ________." }, "references_are_paraphrase": 0 } ]
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3.1 Explain Contribution Margin and Calculate Contribution Margin per Unit, Contribution Margin Ratio, and Total Contribution Margin Before examining contribution margins, let’s review some key concepts: fixed costs, relevant range, variable costs, and contribution margin. Fixed costs are those costs that will not change within a given range of production. For example, in the current case, the fixed costs will be the student sales fee of $100. No matter how many shirts the club produces within the relevant range, the fee will be locked in at $100. The relevant range is the anticipated production activity level. Fixed costs remain constant within a relevant range. If production levels exceed expectations, then additional fixed costs will be required. For example, assume that the students are going to lease vans from their university’s motor pool to drive to their conference. A university van will hold eight passengers, at a cost of $200 per van. If they send one to eight participants, the fixed cost for the van would be $200. If they send nine to sixteen students, the fixed cost would be $400 because they will need two vans. We would consider the relevant range to be between one and eight passengers, and the fixed cost in this range would be $200. If they exceed the initial relevant range, the fixed costs would increase to $400 for nine to sixteen passengers. Variable costs are those costs that vary per unit of production. Direct materials are often typical variable costs, because you normally use more direct materials when you produce more items. In our example, if the students sold 100 shirts, assuming an individual variable cost per shirt of $10, the total variable costs would be $1,000 (100 × $10). If they sold 250 shirts, again assuming an individual variable cost per shirt of $10, then the total variable costs would $2,500 (250 × $10). Contribution margin is the amount by which a product’s selling price exceeds its total variable cost per unit. This difference between the sales price and the per unit variable cost is called the contribution margin because it is the per unit contribution toward covering the fixed costs. It typically is calculated by comparing the sales revenue generated by the sale of one item versus the variable cost of the item: In our example, the sales revenue from one shirt is $15 and the variable cost of one shirt is $10, so the individual contribution margin is $5. This $5 contribution margin is assumed to first cover fixed costs first and then realized as profit. As you will see, it is not just small operations, such as the accounting club scenario provided in Why It Matters , that benefit from cost-volume-profit (CVP) analysis. At some point, all businesses find themselves asking the same basic questions: How many units must be sold in order to reach a desired income level? How much will each unit cost? How much of the sales price from each unit will help cover our fixed costs? For example, Starbucks faces these same questions every day, only on a larger scale. When they introduce new menu items, such as seasonal specialty drinks, they must determine the fixed and variable costs associated with each item. Adding menu items may not only increase their fixed costs in the short run (via advertising and promotions) but will bring new variable costs. Starbucks needs to price these drinks in a way that covers the variable costs per unit and additional fixed costs and contributes to overall net income. Regardless of how large or small the enterprise, understanding how fixed costs, variable costs, and volume are related to income is vital for sound decision-making. Understanding how to use fixed costs, variable costs, and sales in CVP analyses requires an understanding of the term margin. You may have heard that restaurants and grocery stores have very low margins, while jewelry stores and furniture stores have very high margins. What does “margin” mean? In the broadest terms, margin is the difference between a product or service's selling price and its cost of production. Recall the accounting club’s T-shirt sale. The difference between the sales price per T-shirt and the purchase price of the T-shirts was the accounting club’s margin: Recall that Building Blocks of Managerial Accounting explained the characteristics of fixed and variable costs and introduced the basics of cost behavior. Let’s now apply these behaviors to the concept of contribution margin. The company will use this “margin” to cover fixed expenses and hopefully to provide a profit. Let’s begin by examining contribution margin on a per unit basis. Unit Contribution Margin When the contribution margin is calculated on a per unit basis, it is referred to as the contribution margin per unit or unit contribution margin . You can find the contribution margin per unit using the equation shown in Figure 3.2 . It is important to note that this unit contribution margin can be calculated either in dollars or as a percentage. To demonstrate this principle, let’s consider the costs and revenues of Hicks Manufacturing, a small company that manufactures and sells birdbaths to specialty retailers. Hicks Manufacturing sells its Blue Jay Model for $100 and incurs variable costs of $20 per unit. In order to calculate their per unit contribution margin, we use the formula in Figure 3.2 to determine that on a per unit basis, their contribution margin is: This means that for every Blue Jay model they sell, they will have $80 to contribute toward covering fixed costs, such as rent, insurance, and manager salaries. But Hicks Manufacturing manufactures and sells more than one model of birdbath. They also sell a Cardinal Model for $75, and these birdbaths incur variable costs of $15 per unit. For the Cardinal Model, their contribution margin on a per unit basis is the $75 sales price less the $15 per unit variable costs is as follows: This demonstrates that, for every Cardinal model they sell, they will have $60 to contribute toward covering fixed costs and, if there is any left, toward profit. Every product that a company manufactures or every service a company provides will have a unique contribution margin per unit. In these examples, the contribution margin per unit was calculated in dollars per unit, but another way to calculate contribution margin is as a ratio (percentage). Contribution Margin Ratio The contribution margin ratio is the percentage of a unit’s selling price that exceeds total unit variable costs. In other words, contribution margin is expressed as a percentage of sales price and is calculated using this formula: For Hicks Manufacturing and their Blue Jay Model, the contribution margin ratio will be At a contribution margin ratio of 80%, approximately $0.80 of each sales dollar generated by the sale of a Blue Jay Model is available to cover fixed expenses and contribute to profit. The contribution margin ratio for the birdbath implies that, for every $1 generated by the sale of a Blue Jay Model, they have $0.80 that contributes to fixed costs and profit. Thus, 20% of each sales dollar represents the variable cost of the item and 80% of the sales dollar is margin. Just as each product or service has its own contribution margin on a per unit basis, each has a unique contribution margin ratio. Although this process is extremely useful for analyzing the profitability of a single product, good, or service, managers also need to see the “big picture” and will examine contribution margin in total across all products, goods, or services. Your Turn Margin at the Kiosk You rent a kiosk in the mall for $300 a month and use it to sell T-shirts with college logos from colleges and universities all over the world. You sell each T-shirt for $25, and your cost for each shirt is $15. You also pay your sales person a commission of $0.50 per T-shirt sold in addition to a salary of $400 per month. Construct a contribution margin income statement for two different months: in one month, assume 100 T-shirts are sold, and in the other, assume 200 T-shirts are sold. Solution Total Contribution Margin This “big picture” is gained by calculating total contribution margin —the total amount by which total sales exceed total variable costs. We calculate total contribution margin by multiplying per unit contribution margin by sales volume or number of units sold. This approach allows managers to determine how much profit a company is making before paying its fixed expenses. For Hicks Manufacturing, if the managers want to determine how much their Blue Jay Model contributes to the overall profitability of the company, they can calculate total contribution margin as follows: For the month of April, sales from the Blue Jay Model contributed $36,000 toward fixed costs. Looking at contribution margin in total allows managers to evaluate whether a particular product is profitable and how the sales revenue from that product contributes to the overall profitability of the company. In fact, we can create a specialized income statement called a contribution margin income statement to determine how changes in sales volume impact the bottom line. To illustrate how this form of income statement can be used, contribution margin income statements for Hicks Manufacturing are shown for the months of April and May. In April, Hicks sold 500 Blue Jay Models at $100 per unit, which resulted in the operating income shown on the contribution margin income statement: In May, 750 of the Blue Jay models were sold as shown on the contribution margin income statement. When comparing the two statements, take note of what changed and what remained the same from April to May. Using this contribution margin format makes it easy to see the impact of changing sales volume on operating income. Fixed costs remained unchanged; however, as more units are produced and sold, more of the per-unit sales price is available to contribute to the company’s net income. Before going further, let’s note several key points about CVP and the contribution margin income statement. First, the contribution margin income statement is used for internal purposes and is not shared with external stakeholders. Secondly, in this specialized income statement, when “ operating income” is shown, it actually refers to “net operating income” without regard to income taxes . Companies can also consider taxes when performing a CVP analysis to project both net operating income and net income. (The preparation of contribution margin income statements with regard to taxes is covered in advanced accounting courses; here, we will consider net income as net operating income without regard to taxes.) Regardless of whether contribution margin is calculated on a per-unit basis, calculated as a ratio, or incorporated into an income statement, all three express how much sales revenue is available to cover fixed expenses and contribute to profit. Let’s examine how all three approaches convey the same financial performance, although represented somewhat differently. You will recall that the per-unit contribution margin was $80 for a Hicks Blue Jay birdbath. When Hicks sold 500 units, each unit contributed $80 to fixed expenses and profit, which can be verified from April’s income statement: Now, let’s use May’s Contribution Margin Income Statement as previously calculated to verify the contribution margin based on the contribution margin ratio previously calculated, which was 80%, by applying this formula: Regardless of how contribution margin is expressed, it provides critical information for managers. Understanding how each product, good, or service contributes to the organization’s profitability allows managers to make decisions such as which product lines they should expand or which might be discontinued. When allocating scarce resources, the contribution margin will help them focus on those products or services with the highest margin, thereby maximizing profits. The Evolution of Cost-Volume-Profit Relationships The CVP relationships of many organizations have become more complex recently because many labor-intensive jobs have been replaced by or supplemented with technology, changing both fixed and variable costs. For those organizations that are still labor-intensive, the labor costs tend to be variable costs, since at higher levels of activity there will be a demand for more labor usage. For example, assuming one worker is needed for every 50 customers per hour, we might need two workers for an average sales season, but during the Thanksgiving and Christmas season, the store might experience 250 customers per hour and thus would need five workers. However, the growing trend in many segments of the economy is to convert labor-intensive enterprises (primarily variable costs) to operations heavily dependent on equipment or technology (primarily fixed costs). For example, in retail, many functions that were previously performed by people are now performed by machines or software, such as the self-checkout counters in stores such as Walmart , Costco , and Lowe’s . Since machine and software costs are often depreciated or amortized, these costs tend to be the same or fixed, no matter the level of activity within a given relevant range. In China, completely unmanned grocery stores have been created that use facial recognition for accessing the store. Patrons will shop, bag the purchased items, leave the store, and be billed based on what they put in their bags. Along with managing the purchasing process, inventory is maintained by sensors that let managers know when they need to restock an item. In the United States, similar labor-saving processes have been developed, such as the ability to order groceries or fast food online and have it ready when the customer arrives. Another major innovation affecting labor costs is the development of driverless cars and trucks (primarily fixed costs), which will have a major impact on the number of taxi and truck drivers in the future (primarily variable costs). Do these labor-saving processes change the cost structure for the company? Are variable costs decreased? What about fixed costs? Let’s look at this in more detail. When ordering food through an app, there is no need to have an employee take the order, but someone still needs to prepare the food and package it for the customer. The variable costs associated with the wages of order takers will likely decrease, but the fixed costs associated with additional technology to allow for online ordering will likely increase. When grocery customers place their orders online, this not only requires increased fixed costs for the new technology, but it can also increase variable labor costs, as employees are needed to fill customers’ online orders. Many stores may move cashier positions to online order fulfillment rather than hiring additional employees. Other stores may have employees fill online grocery orders during slow or downtimes. Using driverless cars and trucks decreases the variable costs tied to the wages of the drivers but requires a major investment in fixed-cost assets—the autonomous vehicles—and companies would need to charge prices that allowed them to recoup their expensive investments in the technology as well as make a profit. Alternatively, companies that rely on shipping and delivery companies that use driverless technology may be faced with an increase in transportation or shipping costs (variable costs). These costs may be higher because technology is often more expensive when it is new than it will be in the future, when it is easier and more cost effective to produce and also more accessible. A good example of the change in cost of a new technological innovation over time is the personal computer, which was very expensive when it was first developed but has decreased in cost significantly since that time. The same will likely happen over time with the cost of creating and using driverless transportation. You might wonder why a company would trade variable costs for fixed costs. One reason might be to meet company goals, such as gaining market share. Other reasons include being a leader in the use of innovation and improving efficiencies. If a company uses the latest technology, such as online ordering and delivery, this may help the company attract a new type of customer or create loyalty with longstanding customers. In addition, although fixed costs are riskier because they exist regardless of the sales level, once those fixed costs are met, profits grow. All of these new trends result in changes in the composition of fixed and variable costs for a company and it is this composition that helps determine a company’s profit. As you will learn in future chapters, in order for businesses to remain profitable, it is important for managers to understand how to measure and manage fixed and variable costs for decision-making. In this chapter, we begin examining the relationship among sales volume, fixed costs, variable costs, and profit in decision-making. We will discuss how to use the concepts of fixed and variable costs and their relationship to profit to determine the sales needed to break even or to reach a desired profit. You will also learn how to plan for changes in selling price or costs, whether a single product, multiple products, or services are involved. Think It Through Deciding Between Orders You are evaluating orders from two new customers, but you will only be able to accept one of the orders without increasing your fixed costs. Management has directed you to choose the one that is most profitable for the company. Customer A is ordering 500 units and is willing to pay $200 per unit, and these units have a contribution margin of $60 per unit. Customer B is ordering 1,000 units and is willing to pay $140 per unit, and these units have a contribution margin ratio of 40%. Which order do you select and why? Link to Learning Watch this video from Investopedia reviewing the concept of contribution margin to learn more. Keep in mind that contribution margin per sale first contributes to meeting fixed costs and then to profit. 3.2 Calculate a Break-Even Point in Units and Dollars In Building Blocks of Managerial Accounting , you learned how to determine and recognize the fixed and variable components of costs, and now you have learned about contribution margin. Those concepts can be used together to conduct cost-volume-profit (CVP) analysis , which is a method used by companies to determine what will occur financially if selling prices change, costs (either fixed or variable) change, or sales/production volume changes. It is important, first, to make several assumptions about operations in order to understand CVP analysis and the associated contribution margin income statement. However, while the following assumptions are typical in CVP analysis, there can be exceptions. For example, while we typically assume that the sales price will remain the same, there might be exceptions where a quantity discount might be allowed. Our CVP analysis will be based on these assumptions: Costs are linear and can clearly be designated as either fixed or variable. In other words, fixed costs remain fixed in total over the relevant range and variable costs remain fixed on a per-unit basis. For example, if a company has the capability of producing up to 1,000 units a month of a product given its current resources, the relevant range would be 0 to 1,000. If they decided that they wanted to produce 1,800 units a month, they would have to secure additional production capacity. While they might be able to add an extra production shift and then produce 1,800 units a month without buying an additional machine that would increase production capacity to 2,000 units a month, companies often have to buy additional production equipment to increase their relevant range. In this example, the production capacity between 1,800 and 2,000 would be an expense that currently would not provide additional contribution toward fixed costs. Selling price per unit remains constant and does not increase or decrease based on volume (i.e., customers are not given discounts based on quantity purchased). In the case of manufacturing businesses, inventory does not change because we make the assumption that all units produced are sold. In the case of a company that sells multiple products, the sales mix remains constant. For example, if we are a beverage supplier, we might assume that our beverage sales are 3 units of coffee pods and two units of tea bags. Using these assumptions, we can begin our discussion of CVP analysis with the break-even point. Basics of the Break-Even Point The break-even point is the dollar amount (total sales dollars) or production level (total units produced) at which the company has recovered all variable and fixed costs. In other words, no profit or loss occurs at break-even because Total Cost = Total Revenue. Figure 3.3 illustrates the components of the break-even point: The basic theory illustrated in Figure 3.3 is that, because of the existence of fixed costs in most production processes, in the first stages of production and subsequent sale of the products, the company will realize a loss. For example, assume that in an extreme case the company has fixed costs of $20,000, a sales price of $400 per unit and variable costs of $250 per unit, and it sells no units. It would realize a loss of $20,000 (the fixed costs) since it recognized no revenue or variable costs. This loss explains why the company’s cost graph recognized costs (in this example, $20,000) even though there were no sales. If it subsequently sells units, the loss would be reduced by $150 (the contribution margin) for each unit sold. This relationship will be continued until we reach the break-even point, where total revenue equals total costs. Once we reach the break-even point for each unit sold the company will realize an increase in profits of $150. For each additional unit sold, the loss typically is lessened until it reaches the break-even point. At this stage, the company is theoretically realizing neither a profit nor a loss. After the next sale beyond the break-even point, the company will begin to make a profit, and the profit will continue to increase as more units are sold. While there are exceptions and complications that could be incorporated, these are the general guidelines for break-even analysis. As you can imagine, the concept of the break-even point applies to every business endeavor—manufacturing, retail, and service. Because of its universal applicability, it is a critical concept to managers, business owners, and accountants. When a company first starts out, it is important for the owners to know when their sales will be sufficient to cover all of their fixed costs and begin to generate a profit for the business. Larger companies may look at the break-even point when investing in new machinery, plants, or equipment in order to predict how long it will take for their sales volume to cover new or additional fixed costs. Since the break-even point represents that point where the company is neither losing nor making money, managers need to make decisions that will help the company reach and exceed this point as quickly as possible. No business can operate for very long below break-even. Eventually the company will suffer losses so great that they are forced to close their doors. Ethical Considerations Break-Even Analysis and Profitability The first step in determining the viability of the business decision to sell a product or provide a service is analyzing the true cost of the product or service and the timeline of payment for the product or service. Ethical managers need an estimate of a product or service's cost and related revenue streams to evaluate the chance of reaching the break-even point. Determining an accurate price for a product or service requires a detailed analysis of both the cost and how the cost changes as the volume increases. This analysis includes the timing of both costs and receipts for payment, as well as how these costs will be financed. An example is an IT service contract for a corporation where the costs will be frontloaded. When costs or activities are frontloaded, a greater proportion of the costs or activities occur in an earlier stage of the project. An IT service contract is typically employee cost intensive and requires an estimate of at least 120 days of employee costs before a payment will be received for the costs incurred. An IT service contract for $100,000 in monthly services with a 30% profit margin will require 4 months of upfront financing of $280,000 balanced over the four months before a single payment is received. The overall profit at a specific point in time requires a careful determination of all of the costs associated with creating and selling the product or providing the service. An ethical managerial accountant will provide a realistic cost estimate, regardless of management's desire to sell a product or provide a service. What might be a lucrative product on its face needs additional analysis provided by the managerial accountant. To illustrate the concept of break-even, we will return to Hicks Manufacturing and look at the Blue Jay birdbath they manufacture and sell. Link to Learning Watch this video of an example of performing the first steps of cost-volume-profit analysis to learn more. Sales Where Operating Income Is $0 Hicks Manufacturing is interested in finding out the point at which they break even selling their Blue Jay Model birdbath. They will break even when the operating income is $0. The operating income is determined by subtracting the total variable and fixed costs from the sales revenue generated by an enterprise. In other words, the managers at Hicks want to know how many Blue Jay birdbaths they will need to sell in order to cover their fixed expenses and break even. Information on this product is: In order to find their break-even point, we will use the contribution margin for the Blue Jay and determine how many contribution margins we need in order to cover the fixed expenses, as shown in the formula in Figure 3.4 . Applying this to Hicks calculates as: $18,000 $80 = 225 units $18,000 $80 = 225 units What this tells us is that Hicks must sell 225 Blue Jay Model birdbaths in order to cover their fixed expenses. In other words, they will not begin to show a profit until they sell the 226 th unit. This is illustrated in their contribution margin income statement. The break-even point for Hicks Manufacturing at a sales volume of $22,500 (225 units) is shown graphically in Figure 3.5 . As you can see, when Hicks sells 225 Blue Jay Model birdbaths, they will make no profit, but will not suffer a loss because all of their fixed expenses are covered. However, what happens when they do not sell 225 units? If that happens, their operating income is negative. Sales Where Operating Income Is Negative In a recent month, local flooding caused Hicks to close for several days, reducing the number of units they could ship and sell from 225 units to 175 units. The information in Figure 3.6 reflects this drop in sales. At 175 units ($17,500 in sales), Hicks does not generate enough sales revenue to cover their fixed expenses and they suffer a loss of $4,000. They did not reach the break-even point of 225 units. Sales Where Operating Income Is Positive What happens when Hicks has a busy month and sells 300 Blue Jay birdbaths? We have already established that the contribution margin from 225 units will put them at break-even. When sales exceed the break-even point the unit contribution margin from the additional units will go toward profit. This is reflected on their income statement. Again, looking at the graph for break-even ( Figure 3.8 ), you will see that their sales have moved them beyond the point where total revenue is equal to total cost and into the profit area of the graph. Hicks Manufacturing can use the information from these different scenarios to inform many of their decisions about operations, such as sales goals. However, using the contribution margin per unit is not the only way to determine a break-even point. Recall that we were able to determine a contribution margin expressed in dollars by finding the contribution margin ratio. We can apply that contribution margin ratio to the break-even analysis to determine the break-even point in dollars. For example, we know that Hicks had $18,000 in fixed costs and a contribution margin ratio of 80% for the Blue Jay model. We will use this ratio ( Figure 3.9 ) to calculate the break-even point in dollars. Applying the formula to Hicks gives this calculation: $18,000 0.80 = $22,500 $18,000 0.80 = $22,500 Hicks Manufacturing will have to generate $22,500 in monthly sales in order to cover all of their fixed costs. In order for us to verify that Hicks’ break-even point is $22,500 (or 225 units) we will look again at the contribution margin income statement at break-even: By knowing at what level sales are sufficient to cover fixed expenses is critical, but companies want to be able to make a profit and can use this break-even analysis to help them. Think It Through The Cost of a Haircut You are the manager of a hair salon and want to know how many ladies’ haircuts your salon needs to sell in a month in order to cover the fixed costs of running the salon. You have determined that, at the current price of $35 per haircut, you have $20 in variable costs associated with each cut. These variable costs include stylist wages, hair product, and shop supplies. Your fixed costs are $3,000 per month. You perform a break-even analysis on a per-unit basis and discover the following: You have 4 stylists plus yourself working in the salon and are open 6 days per week. Considering the break-even point and the number of available stylists, will the salon ever break even? If it does, what will need to happen? What can be done to achieve the break-even point? Examples of the Effects of Variable and Fixed Costs in Determining the Break-Even Point Companies typically do not want to simply break even, as they are in business to make a profit. Break-even analysis also can help companies determine the level of sales (in dollars or in units) that is needed to make a desired profit. The process for factoring a desired level of profit into a break-even analysis is to add the desired level of profit to the fixed costs and then calculate a new break-even point. We know that Hicks Manufacturing breaks even at 225 Blue Jay birdbaths, but what if they have a target profit for the month of July? They can simply add that target to their fixed costs. By calculating a target profit, they will produce and (hopefully) sell enough bird baths to cover both fixed costs and the target profit. If Hicks wants to earn $16,000 in profit in the month of May, we can calculate their new break-even point as follows: Target Profit = Fixed costs + desired profit Contribution margin per unit = $18,000 + $16,000 $80 = 425 units Target Profit = Fixed costs + desired profit Contribution margin per unit = $18,000 + $16,000 $80 = 425 units We have already established that the $18,000 in fixed costs is covered at the 225 units mark, so an additional 200 units will cover the desired profit (200 units × $80 per unit contribution margin = $16,000). Alternatively, we can calculate this in terms of dollars by using the contribution margin ratio. Target Profit = Fixed costs + desired profit Contribution margin ratio = $18,000 + $16,000 0.80 = $42,500 Target Profit = Fixed costs + desired profit Contribution margin ratio = $18,000 + $16,000 0.80 = $42,500 As done previously, we can confirm this calculation using the contribution margin income statement: Note that the example calculations ignored income taxes, which implies we were finding target operating income. However, companies may want to determine what level of sales would generate a desired after-tax profit. To find the break-even point at a desired after-tax profit, we simply need to convert the desired after-tax profit to the desired pre-tax profit, also referred to as operating income, and then follow through as in the example. Suppose Hicks wants to earn $24,000 after-taxes, what level of sales (units and dollars) would be needed to meet that goal? First, the after-tax profit needs to be converted to a pre-tax desired profit: Pre-tax desired profit = After-tax profit (1 – tax rate) Pre-tax desired profit = After-tax profit (1 – tax rate) If the tax rate for Hicks is 40%, then the $24,000 after-tax profit is equal to a pre-tax profit of $40,000: $40,000 = $24,000 (1 – 0.40) $40,000 = $24,000 (1 – 0.40) The tax rate indicates the amount of tax expense that will result from any profits and 1 – tax rate indicates the amount remaining after taking out tax expense. The concept is similar to buying an item on sale. If an item costs $80 and is on sale for 40% off, then the amount being paid for the item is 60% of the sale price, or $48 ($80 × 60%). Another way to find this involves two steps. First find the discount ($80 × 40% = $32) and then subtract the discount from the sales price ($80 – $32 = $48). Taxes and profit work in a similar fashion. If we know the profit before tax is $100,000 and the tax rate is 30%, then tax expenses are $100,000 × 30% = $30,000. This means the after-tax income is $100,000 – $30,000 = $70,000. However, in most break-even situations, as well as other decision-making areas, the desired after-tax profit is known, and the pre-tax profit must be determined by dividing the after-tax profit by 1 – tax rate. To demonstrate the combination of both a profit and the after-tax effects and subsequent calculations, let’s return to the Hicks Manufacturing example. Let’s assume that we want to calculate the target volume in units and revenue that Hicks must sell to generate an after-tax return of $24,000, assuming the same fixed costs of $18,000. Since we earlier determined $24,000 after-tax equals $40,000 before-tax if the tax rate is 40%, we simply use the break-even at a desired profit formula to determine the target sales. Target sales = ( Fixed costs + Desired profit ) Contribution margin per unit = ( $ 18,000 + $ 40,000 ) $ 80 = 725 units Target sales = ( Fixed costs + Desired profit ) Contribution margin per unit = ( $ 18,000 + $ 40,000 ) $ 80 = 725 units This calculation demonstrates that Hicks would need to sell 725 units at $100 a unit to generate $72,500 in sales to earn $24,000 in after-tax profits. Alternatively, target sales in sales dollars could have been calculated using the contribution margin ratio: Target sales = ( Fixed costs + Desired profit ) Contribution margin per unit = ( $ 18,000 + $ 40,000 ) 0.80 = $72,500 Target sales = ( Fixed costs + Desired profit ) Contribution margin per unit = ( $ 18,000 + $ 40,000 ) 0.80 = $72,500 Once again, the contribution margin income statement proves the sales and profit relationships. Thus, to calculate break-even point at a particular after-tax income, the only additional step is to convert after-tax income to pre-tax income prior to utilizing the break-even formula. It is good to understand the impact of taxes on break-even analysis as companies will often want to plan based on the after-tax effects of a decision as the after-tax portion of income is the only part of income that will be available for future use. Application of Break-Even Concepts for a Service Organization Because break-even analysis is applicable to any business enterprise, we can apply these same principles to a service organization. For example, Marshall & Hirito is a mid-sized accounting firm that provides a wide range of accounting services to its clients but relies heavily on personal income tax preparation for much of its revenue. They have analyzed the cost to the firm associated with preparing these returns. They have determined the following cost structure for the preparation of a standard 1040A Individual Income Tax Return: They have fixed costs of $14,000 per month associated with the salaries of the accountants who are responsible for preparing the Form 1040A . In order to determine their break-even point, they first determine the contribution margin for the Form 1040A as shown: Now they can calculate their break-even point: Break-Even Point in Units = Total fixed costs Contribution margin per unit = $14,000 $250 = 56 returns Break-Even Point in Units = Total fixed costs Contribution margin per unit = $14,000 $250 = 56 returns Remember, this is the break-even point in units (the number of tax returns) but they can also find a break-even point expressed in dollars by using the contribution margin ratio. First, they find the contribution margin ratio. Then, they use the ratio to calculate the break-even point in dollars: Break-Even Point in Dollars = Fixed costs Contribution margin ratio = $14,000 0.625 = $22,400 Break-Even Point in Dollars = Fixed costs Contribution margin ratio = $14,000 0.625 = $22,400 We can confirm these figures by preparing a contribution margin income statement: Therefore, as long as Marshall & Hirito prepares 56 Form 1040 income tax returns, they will earn no profit but also incur no loss. What if Marshall & Hirito has a target monthly profit of $10,000? They can use the break-even analysis process to determine how many returns they will need to prepare in order to cover their fixed expenses and reach their target profit: Target Profit = Fixed costs + desired profit Contribution margin per unit = $14,000 + $10,000 $250 = 96 returns Target Profit = Fixed costs + desired profit Contribution margin per unit = $14,000 + $10,000 $250 = 96 returns They will need to prepare 96 returns during the month in order to realize a $10,000 profit. Expressing this in dollars instead of units requires that we use the contribution margin ratio as shown: Target Profit = Fixed costs + desired profit Contribution margin per unit = $14,000 + $10,000 0.625 = $38,400 Target Profit = Fixed costs + desired profit Contribution margin per unit = $14,000 + $10,000 0.625 = $38,400 Marshall & Hirito now knows that, in order to cover the fixed costs associated with this service, they must generate $38,400 in revenue. Once again, let’s verify this by constructing a contribution margin income statement: As you can see, the $38,400 in revenue will not only cover the $14,000 in fixed costs, but will supply Marshall & Hirito with the $10,000 in profit (net income) they desire. As you’ve learned, break-even can be calculated using either contribution margin per unit or the contribution margin ratio. Now that you have seen this process, let’s look at an example of these two concepts presented together to illustrate how either method will provide the same financial results. Suppose that Channing’s Chairs designs, builds, and sells unique ergonomic desk chairs for home and business. Their bestselling chair is the Spine Saver. Figure 3.10 illustrates how Channing could determine the break-even point in sales dollars using either the contribution margin per unit or the contribution margin ratio. Note that in either scenario, the break-even point is the same in dollars and units, regardless of approach. Thus, you can always find the break-even point (or a desired profit) in units and then convert it to sales by multiplying by the selling price per unit. Alternatively, you can find the break-even point in sales dollars and then find the number of units by dividing by the selling price per unit. Your Turn College Creations College Creations, Inc (CC), builds a loft that is easily adaptable to most dorm rooms or apartments and can be assembled into a variety of configurations. Each loft is sold for $500, and the cost to produce one loft is $300, including all parts and labor. CC has fixed costs of $100,000. What happens if CC produces nothing? Now, assume CC produces and sells one unit (loft). What are their financial results? Now, what do you think would happen if they produced and sold 501 units? How many units would CC need to sell in order to break even? How many units would CC need to sell if they wanted to have a pretax profit of $50,000? Solution A. If they produce nothing, they will still incur fixed costs of $100,000. They will suffer a net loss of $100,000. B. If they sell one unit, they will have a net loss of $99,800. C. If they produce 501 units, they will have operating income of $200 as shown: D. Break-even can be determined by FC/CM per unit: $100,000 ÷ $200 = 500. Five hundred lofts must be sold to break even. E. The desired profit can be treated like a fixed cost, and the target profit would be (FC + Desired Profit)/CM or ($100,000 + $50,000) ÷ $200 = 750. Seven hundred fifty lofts need to be sold to reach a desired income of $50,000. Another way to have found this is to know that, after fixed costs are met, the $200 per unit contribution margin will go toward profit. The desired profit of $50,000 ÷ $200 per unit contribution margin = 250. This means that 250 additional units must be sold. To break even requires 500 units to be sold, and to reach the desired profit of $50,000 requires an additional 250 units, for a total of 750 units. 3.3 Perform Break-Even Sensitivity Analysis for a Single Product Under Changing Business Situations Finding the break-even point or the sales necessary to meet a desired profit is very useful to a business, but cost-volume-profit analysis also can be used to conduct a sensitivity analysis , which shows what will happen if the sales price, units sold, variable cost per unit, or fixed costs change. Companies use this type of analysis to consider possible scenarios that assist them in planning. Link to Learning Watch this video that shows what happens if one or more of the variables in a break-even analysis is changed to learn more. The Effects on Break-Even under Changing Business Conditions Circumstances often change within a company, within an industry, or even within the economy that impact the decision-making of an organization. Sometimes, these effects are sudden and unexpected, for example, if a hurricane destroyed the factory of a company’s major supplier; other times, they occur more slowly, such as when union negotiations affect your labor costs. In either of these situations, costs to the company will be affected. Using CVP analysis, the company can predict how these changes will affect profits. Changing a Single Variable To demonstrate the effects of changing any one of these variables, consider Back Door Café, a small coffee shop that roasts its own beans to make espresso drinks and gourmet coffee. They also sell a variety of baked goods and T-shirts with their logo on them. They track their costs carefully and use CVP analysis to make sure that their sales cover their fixed costs and provide a reasonable level of profit for the owners. Change in Sales Price The owner of Back Door has one of her employees conduct a survey of the other coffee shops in the area and finds that they are charging $0.75 more for espresso drinks. As a result, the owner wants to determine what would happen to operating income if she increased her price by just $0.50 and sales remained constant, so she performs the following analysis: The only variable that has changed is the $0.50 increase in the price of their espresso drinks, but the net operating income will increase by $750. Another way to think of this increase in income is that, if the sales price increases by $0.50 per expresso drink and the estimated sales are 1,500 units, then this will result in an increase in overall contribution margin of $750. Moreover, since all of the fixed costs were met by the lower sales price, all of this $750 goes to profit. Again, this is assuming the higher sales price does not decrease the number of units sold. Since the other coffee shops will still be priced higher than Back Door, the owner believes that there will not be a decrease in sales volume. When making this adjustment to their sales price, Back Door Café is engaging in target pricing , a process in which a company uses market analysis and production information to determine the maximum price customers are willing to pay for a good or service in addition to the markup percentage. If the good can be produced at a cost that allows both the desired profit percentage as well as deliver the good at a price acceptable to the customer, then the company should proceed with the product; otherwise, the company will not achieve its desired profit goals. Change in Variable Cost In March, the owner of Back Door receives a letter from her cups supplier informing her that there is a $0.05 price increase due to higher material prices. Assume that the example uses the original $3.75 per unit sales price. The owner wants to know what would happen to net operating income if she absorbs the cost increase, so she performs the following analysis: She is surprised to see that just a $0.05 increase in variable costs (cups) will reduce her net income by $75. The owner may decide that she is fine with the lower income, but if she wants to maintain her income, she will need to find a new cup supplier, reduce other costs, or pass the price increase on to her customers. Because the increase in the cost of the cups was a variable cost, the impact on net income can be seen by taking the increase in cost per unit, $0.05, and multiplying that by the units expected to be sold, 1,500, to see the impact on the contribution margin, which in this case would be a decrease of $75. This also means a decrease in net income of $75. Change in Fixed Cost Back Door Café’s lease is coming up for renewal. The owner calls the landlord to indicate that she wants to renew her lease for another 5 years. The landlord is happy to hear she will continue renting from him but informs her that the rent will increase $225 per month. She is not certain that she can afford an additional $225 per month and tells him she needs to look at her numbers and will call him back. She pulls out her CVP spreadsheet and adjusts her monthly fixed costs upwards by $225. Assume that the example uses the original $3.75 per unit sales price. The results of her analysis of the impact of the rent increase on her annual net income are: Because the rent increase is a change in a fixed cost, the contribution margin per unit remains the same. However, the break-even point in both units and dollars increase because more units of contribution are needed to cover the $225 monthly increase in fixed costs. If the owner of the Back Door agrees to the increase in rent for the new lease, she will likely look for ways to increase the contribution margin per unit to offset this increase in fixed costs. In each of the prior examples, only one variable was changed—sales volume, variable costs, or fixed costs. There are some generalizations that can be made regarding how a change in any one of these variables affects the break-even point. These generalizations are summarized in Table 3.1 . Generalizations Regarding Changes in Break-Even Point from a Change in One Variable Condition Result Sales Price Increases Break-Even Point Decreases (Contribution Margin is Higher, Need Fewer Sales to Break Even) Sales Price Decreases Break-Even Point Increases (Contribution Margin is Lower, Need More Sales to Break Even) Variable Costs Increase Break-Even Point Increases (Contribution Margin is Lower, Need More Sales to Break Even) Variable Costs Decrease Break-Even Point Decreases (Contribution Margin is Higher, Need Fewer Sales to Break Even) Fixed Costs Increase Break-Even Point Increases (Contribution Margin Does Not Change, but Need More Sales to Meet Fixed Costs) Fixed Costs Decrease Break-Even Point Decreases (Contribution Margin Does Not Change, but Need Fewer Sales to Meet Fixed Costs) Table 3.1 Link to Learning Watch this video that walks through, step by step, how to calculate break even in units and dollars and at a desired profit or sales level to learn more. Changing Multiple Variables We have analyzed situations in which one variable changes, but often, more than one change will occur at a time. For example, a company may need to lower its selling price to compete, but they may also be able to lower certain variable costs by switching suppliers. Suppose Back Door Café has the opportunity to purchase a new espresso machine that will reduce the amount of coffee beans required for an espresso drink by putting the beans under higher pressure. The new machine will cost $15,000, but it will decrease the variable cost per cup by $0.05. The owner wants to see what the effect will be on the net operating income and break-even point if she purchases the new machine. She has arranged financing for the new machine and the monthly payment will increase her fixed costs by $400 per month. When she conducts this analysis, she gets the following results: Looking at the “what-if” analysis, we see that the contribution margin per unit increases because of the $0.05 reduction in variable cost per unit. As a result, she has a higher total contribution margin available to cover fixed expenses. This is good, because the monthly payment on the espresso machine represents an increased fixed cost. Even though the contribution margin ratio increases, it is not enough to totally offset the increase in fixed costs, and her monthly break-even point has risen from $4,125.00 to $4,687.50. If the new break-even point in units is a realistic number (within the relevant range), then she would decide to purchase the new machine because, once it has been paid for, her break-even point will fall and her net income will rise. Performing this analysis is an effective way for managers and business owners to look into the future, so to speak, and see what impact business decisions will have on their financial position. Let’s look at another option the owner of the Back Door Café has to consider when making the decision about this new machine. What would happen if she purchased the new machine to realize the variable cost savings and also raised her price by just $0.20? She feels confident that such a small price increase will go virtually unnoticed by her customers but may help her offset the increase in fixed costs. She runs the analysis as follows: The analysis shows the expected result: an increase in the per-unit contribution margin, a decrease in the break-even point, and an increase in the net operating income. She has changed three variables in her costs—sales price, variable cost, and fixed cost. In fact, the small price increase almost gets her back to the net operating income she realized before the purchase of the new expresso machine. By now, you should begin to understand why CVP analysis is such a powerful tool. The owner of Back Door Café can run an unlimited number of these what-if scenarios until she meets the financial goals for her company. There are very few tools in managerial accounting as powerful and meaningful as a cost-volume-profit analysis. Concepts In Practice Value Menus In January 2018, McDonald’s brought back its $1 value menu. After discontinuing its popular Dollar Menu six years previously, the new version has a list of items priced not only at $1, but at $2 and $3 as well. How can McDonald’s afford to offer menu items at this discounted price? Volume! Although the margin on each unit is very small, the food chain hopes to make up the difference in quantity. They also hope that consumers will add higher priced (and higher margin) items to their orders. 1 The strategy is not without its risks, however, as rising food or labor costs could put franchisees in a position where the value pricing does not cover their product costs. Rivals Taco Bell and Dunkin’ Donuts have aggressively marketed their value menus, making it almost impossible for McDonald’s to ignore the growing trend among consumers for “value pricing.” Watch this video to see what McDonald’s is offering consumers. 1 Zlati Meyer. “McDonald’s Hope Customers Buck Up Thursday to New Dollar Menu.” USA Today. January 3, 2018. https://www.usatoday.com/story/money/2018/01/03/mcdonalds-hopes-customers-buck-up-thursday-new-dollar-menu/996350001/ 3.4 Perform Break-Even Sensitivity Analysis for a Multi-Product Environment Under Changing Business Situations Up to this point in our CVP analysis, we have assumed that a company only sells one product, but we know that, realistically, this is not the case. Most companies operate in a multi-product environment , in which they sell different products, manufacture different products, or offer different types of services. Companies price each one of their products or services differently, and the costs associated with each of those products or services vary as well. In addition, companies have limited resources, such as time and labor, and must decide which products to sell or produce and in what quantities, or which services to offer in order to be the most profitable. These profitability considerations are often what contributes substance to a sales mix decision The Basics of Break-Even Analysis in a Multi-Product Environment In order to perform a break-even analysis for a company that sells multiple products or provides multiple services, it is important to understand the concept of a sales mix. A sales mix represents the relative proportions of the products that a company sells—in other words, the percentage of the company’s total revenue that comes from product A, product B, product C, and so forth. Sales mix is important to business owners and managers because they seek to have a mix that maximizes profit, since not all products have the same profit margin. Companies can maximize their profits if they are able to achieve a sales mix that is heavy with high-margin products, goods, or services. If a company focuses on a sales mix heavy with low-margin items, overall company profitability will often suffer. Performing a break-even analysis for these multi-product businesses is more complex because each product has a different selling price, a different variable cost, and, ultimately, a different contribution margin. We must also proceed under the assumption that the sales mix remains constant; if it does change, the CVP analysis must be revised to reflect the change in sales mix. For the sake of clarity, we will also assume that all costs are companywide costs, and each product contributes toward covering these companywide costs. Think It Through Selling Subs You are the manager of a sub shop located near a college campus. The college has recently added a fast-food style café to the student center, which has reduced the number of students eating at your restaurant. Your highest margin items are drinks (a contribution margin of approximately 90%) and vegetarian subs (a contribution margin of approximately 75%). How can you use CVP analysis to help you compete with the college’s café? What would you suggest as possible ways to increase business while maintaining target income levels? Calculating Break-Even Analysis in a Multi-Product Environment When a company sells more than one product or provides more than one service, break-even analysis is more complex because not all of the products sell for the same price or have the same costs associated with them: Each product has its own margin. Consequently, the break-even point in a multi-product environment depends on the mix of products sold. Further, when the mix of products changes, so does the break-even point. If demand shifts and customers purchase more low-margin products, then the break-even point rises. Conversely, if customers purchase more high-margin products, the break-even point falls. In fact, even if total sales dollars remain unchanged, the break-even point can change based on the sales mix. Let’s look at an example of how break-even analysis works in a multi-product environment. In multi-product CVP analysis, the company’s sales mix is viewed as a composite unit , a selection of discrete products associated together in proportion to the sales mix. The composite unit is not sold to customers but is a concept used to calculate a combined contribution margin, which is then used to estimate the break-even point. Think of a composite unit as a virtual basket of fruit that contains the proportion of individual fruits equal to the company’s sales mix. If we purchased these items individually to make the fruit basket, each one would have a separate price and a different contribution margin. This is how a composite unit works in CVP analysis. We calculate the contribution margins of all of the component parts of the composite unit and then use the total to calculate the break-even point. It is important to note that fixed costs are allocated among the various components (products) that make up this composite unit. Should a product be eliminated from the composite unit or sales mix, the fixed costs must be re-allocated among the remaining products. If we use the fruit basket as an example, we can look at the individual fruits that make up the basket: apples, oranges, bananas, and pears. We see that each individual fruit has a selling price and a cost. Each fruit has its own contribution margin. But how would we determine the contribution margin for a composite of fruit, or in other words, for our basket of fruit? For our particular baskets, we will use 5 apples, 3 oranges, 2 bananas, and 1 pear. This means that our product mix is 5:3:2:1, as shown in Figure 3.11 . Notice that the composite contribution margin is based on the number of units of each item that is included in the composite item. If we change the composition of the basket, then the composite contribution margin would change even though contribution margin of the individual items would not change. For example, if we only include 4 apples, the contribution margin of a single apple is still $0.35, but the contribution margin of the apples in the basket is $1.40, not $1.75 as it is when 5 apples are included in the basket. Let’s look at an additional example and see how we find the break-even point for a composite good. We will consider West Brothers for an example of a multi-product break-even analysis. West Brothers manufactures and sells 3 types of house siding: restoration vinyl, architectural vinyl, and builder grade vinyl, each with its own sales price, variable cost, and contribution margin, as shown: The sales mix for West Brothers is 5 ft 2 of builder grade to 3 ft 2 of architectural grade to 2 ft 2 of restoration grade vinyl (a ratio of 5:3:2). This sales mix represents one composite unit, and the selling price of one composite unit is: West Brothers’ fixed costs are $145,000 per year, and the variable costs for one composite unit are: We will calculate the contribution margin of a composite unit for West Brothers using the same formula as before: Applying the formula, we determine that $73 – $42.25 = 30.75. We then use the contribution margin per composite unit to determine West Brothers’ break-even point: Break-Even Point per Composite Unit = Total fixed costs Contribution margin per composite unit = $145,000 $30.75 = 4,715.45 composite units Break-Even Point per Composite Unit = Total fixed costs Contribution margin per composite unit = $145,000 $30.75 = 4,715.45 composite units West Brothers will break even when it sells 4,715.45 (or 4,716 since it can’t sell a partial unit) composite units. To determine how many of each product West Brothers needs to sell, we apply their sales mix ratio (5:3:2) to the break-even quantity as follows: Using a forecasted or estimated contribution margin income statement, we can verify that the quantities listed will place West Brothers at break-even. West Brothers can use this CVP analysis for a wide range of business decisions and for planning purposes. Remember, however, that if the sales mix changes from its current ratio, then the break-even point will change. For planning purposes, West Brothers can change the sales mix, sales price, or variable cost of one or more of the products in the composite unit and perform a “what-if” analysis. Your Turn Margins in the Sales Mix The sales mix of a company selling two products, A and B, is 3:1. The per-unit variable costs is $4 for Product A and $5 for Product B. Product A sells for $10 and product B sells for $9. Fixed costs for the company are $220,000. What is the contribution margin per composite unit? What is the break-even point in composite units? How many units of product A and product B will the company sell at the break-even point? Solution A. B. Break-even per composite unit = 15,385. C. 3.5 Calculate and Interpret a Company’s Margin of Safety and Operating Leverage Our discussion of CVP analysis has focused on the sales necessary to break even or to reach a desired profit, but two other concepts are useful regarding our break-even sales. Those concepts are margin of safety and operating leverage. Margin of Safety A company’s margin of safety is the difference between its current sales and its break-even sales. The margin of safety tells the company how much they could lose in sales before the company begins to lose money, or, in other words, before the company falls below the break-even point. The higher the margin of safety is, the lower the risk is of not breaking even or incurring a loss. In order to calculate margin of safety, we use the following formula: Let’s look at Manteo Machine, a company that machines parts that are then sold and used in the manufacture of farm equipment. For their core product, the break-even analysis is as follows: Interpreting this information tells Manteo Machine that, when sales equal $153,000, they will be at the break-even point. However, as soon as sales fall below this figure, they will have negative net operating income. They have decided that they want a margin of safety of $10,000. They can add this as if it were a fixed cost (very much the same way we added target profit earlier) and then find a new break-even point that includes a $10,000 margin of safety. If they approached it from this perspective, their new break-even would appear as follows: As shown in Figure 3.12 , the margin of safety of 1,900 units is found from (FC + Margin of Safety)/CM per unit = $95,000/$50. Thus, 1,900 units must be sold in order to meet fixed cost and have a $10,000 margin of safety. Another way to see this is to realize the $10,000 margin of safety will be met in $50 increments based on the current contribution margin. This means the company will need to sell an additional 200 units, which is an additional $18,000 in sales to have the desired margin of safety. The true break-even, where only fixed costs were met, was 1,700 units, or $153,000 in sales. The point at which the company would have a $10,000 margin of safety is 1,900 units, or $171,000 in sales. Note that the new level of units is the break-even units of 1,700 plus the 200 units for the margin of safety. The same can be seen for the sales dollar. The new level of desired sales dollars is the break-even sales of $153,000 plus the additional $18,000 in sales for the margin of safety. The margin of safety can also be determined when a company knows its sales volume. For example, Manteo Machine sold 2,500 units in March and wants to know its margin of safety at that sales volume: From this analysis, Manteo Machine knows that sales will have to decrease by $72,000 from their current level before they revert to break-even operations and are at risk to suffer a loss. Ethical Considerations The Importance of Relevant Range Analysis Ethical managerial decision-making requires that information be communicated fairly and objectively. The failure to include the demand for individual products in the company's mixture of products may be misleading. Providing misleading or inaccurate managerial accounting information can lead to a company becoming unprofitable. Ignoring relevant range(s) in setting assumptions about cost behavior and ignoring the actual demand for the product in the company's market also distorts the information provided to management and may cause the management of the company to produce products that cannot be sold. Many companies prefer to consider the margin of safety as a percentage of sales, rather than as a dollar amount. In order to express margin of safety as a percentage, we divide the margin of safety (in dollars) by the total budgeted or actual sales volume. The formula to express margin of safety as a percentage is: Previously, we calculated Manteo Machine’s margin of safety as $72,000. As a percentage, it would be $72,000 $225,000 = 0.32 or 32% $72,000 $225,000 = 0.32 or 32% This tells management that as long as sales do not decrease by more than 32%, they will not be operating at or near the break-even point, where they would run a higher risk of suffering a loss. Often, the margin of safety is determined when sales budgets and forecasts are made at the start of the fiscal year and also are regularly revisited during periods of operational and strategic planning. Operating Leverage In much the same way that managers control the risk of incurring a net loss by watching their margin of safety, being aware of the company’s operating leverage is critical to the financial well-being of the firm. Operating leverage is a measurement of how sensitive net operating income is to a percentage change in sales dollars. Typically, the higher the level of fixed costs, the higher the level of risk. However, as sales volumes increase, the payoff is typically greater with higher fixed costs than with higher variable costs. In other words, the higher the risk the greater the payoff. First, let’s look at this from a general example to understand payoff. Suppose you had $10,000 to invest and you were debating between putting that money in low risk bonds earning 3% or taking a chance and buying stock in a new company that currently is not profitable but has an innovative product that many analysts predict will take off and be the next “big thing.” Obviously, there is more risk with buying the stock than with buying the bonds. If the company remains unprofitable, or fails, you stand to lose all or a portion of your investment ,whereas the bonds are less risky and will continue to pay 3% interest. However, the risk associated with the stock investment could result in a much higher payoff if the company is successful. So how does this relate to fixed costs and companies? Companies have many types of fixed costs including salaries, insurance, and depreciation. These costs are present regardless of our production or sales levels. This makes fixed costs riskier than variable costs, which only occur if we produce and sell items or services. As we sell items, we have learned that the contribution margin first goes to meeting fixed costs and then to profits. Here is an example of how changes in fixed costs affects profitability. Gray Co. has the following income statement: What is the effect of switching $10,000 of fixed costs to variable costs? What is the effect of switching $10,000 of variable costs to fixed costs? Notice that in this instance, the company’s net income stayed the same. Now, look at the effect on net income of changing fixed to variable costs or variable costs to fixed costs as sales volume increases. Assume sales volume increase by 10%. As you can see from this example, moving variable costs to fixed costs, such as making hourly employees salaried, is riskier in that fixed costs are higher. However, the payoff, or resulting net income, is higher as sales volume increases. This is why companies are so concerned with managing their fixed and variable costs and will sometimes move costs from one category to another to manage this risk. Some examples include, as previously mentioned, moving hourly employees (variable) to salaried employees (fixed), or replacing an employee (variable) with a machine (fixed). Keep in mind that managing this type of risk not only affects operating leverage but can have an effect on morale and corporate climate as well. Concepts In Practice Fluctuating Operating Leverage: Why Do Stores Add Self-Service Checkout Lanes? Operating leverage fluctuations result from changes in a company’s cost structure. While any change in either variable or fixed costs will change operating leverage, the fluctuations most often result from management’s decision to shift costs from one category to another. As the next example shows, the advantage can be great when there is economic growth (increasing sales); however, the disadvantage can be just as great when there is economic decline (decreasing sales). This is the risk that must be managed when deciding how and when to cause operating leverage to fluctuate. Consider the impact of reducing variable costs (fewer employee staffed checkout lanes) and increasing fixed costs (more self-service checkout lanes). A store with $125,000,000 per year in sales installs some self-service checkout lanes. This increases its fixed costs by 10% but reduces its variable costs by 5%. As Figure 3.13 shows, at the current sales level, this could produce a whopping 35% increase in net operating income. And, if the change results in higher sales, the increase in net operating income would be even more dramatic. Do the math and you will see that each 1% increase in sales would produce a 6% increase in net operating income: well worth the change, indeed. (in 000s) Without Selfservice Checkout Lanes, With Selfservice Checkout Lanes (respectively): Sales $125,000, 125,000; Variable Costs 93,750, 89,063; Contribution Margin 31,250, 35,938; Fixed Costs 25,000, 27,500; Net Operating Income 6,250 8,438; Percent Increase in Income 35 percent. The company in this example also faces a downside risk, however. If customers disliked the change enough that sales decreased by more than 6%, net operating income would drop below the original level of $6,250 and could even become a loss. Operating leverage has a multiplier effect. A multiplier effect is one in which a change in an input (such as variable cost per unit) by a certain percentage has a greater effect (a higher percentage effect) on the output (such as net income). To explain the concept of a multiplier effect, think of having to open a very large, heavy wooden crate. You could pull and pull with your hands all day and still not exert enough force to get it open. But, what if you used a lever in the form of a pry bar to multiply your effort and strength? For every additional amount of force you apply to the pry bar, a much larger amount of force is applied to the crate. Before you know it, you have the crate open. Operating leverage works much like that pry bar: if operating leverage is high, then a very small increase in sales can result in a large increase in net operating income. How does a company increase its operating leverage? Operating leverage is a function of cost structure, and companies that have a high proportion of fixed costs in their cost structure have higher operating leverage. There is, however, a cautionary side to operating leverage. Since high operating leverage is the result of high fixed costs, if the market for the company’s products, goods, or services shrinks, or if demand for the company’s products, goods, or services declines, the company may find itself obligated to pay for fixed costs with little or no sales revenue to spare. Managers who have made the decision to chase large increases in net operating income through the use of operating leverage have found that, when market demand falls, their only recourse is to close their doors. In fact, many large companies are making the decision to shift costs away from fixed costs to protect them from this very problem. Link to Learning During periods of sales downturns, there are many examples of companies working to shift costs away from fixed costs. This Yahoo Finance article reports that many airlines are changing their cost structure to move away from fixed costs and toward variable costs such as Delta Airlines. Although they are decreasing their operating leverage, the decreased risk of insolvency more than makes up for it. In order to calculate the degree of operating leverage at a given level of sales, we will apply the following formula: To explain further the concept of operating leverage, we will look at two companies and their operating leverage positions: Both companies have the same net income of $85,000, but company B has a higher degree of operating leverage because its fixed costs are higher than that of company A. If we want to see how operating leverage impacts net operating income, then we can apply the following formula: Let’s assume that both company A and company B are anticipating a 10% increase in sales. Based on their respective degrees of operating leverage, what will their percentage change in net operating income be? Company A: 1.71 × 10% = 17.4% Company B: 2.47 × 10% = 24.7% Company A: 1.71 × 10% = 17.4% Company B: 2.47 × 10% = 24.7% For company A, for every 10% increase in sales, net operating income will increase 17.4%. But company B has a much higher degree of operating leverage, and a 10% increase in sales will result in a 24.7% increase in net operating income. These examples clearly show why, during periods of growth, companies have been willing to risk incurring higher fixed costs in exchange for large percentage gains in net operating income. But what happens in periods where income declines? We will return to Company A and Company B, only this time, the data shows that there has been a 20% decrease in sales. Note that the degree of operating leverage changes for each company. The reduced income resulted in a higher operating leverage, meaning a higher level of risk. It is equally important to realize the percentage decrease in income for both companies. The decrease in sales by 20% resulted in a 31.9% decrease in net income for Company A. For Company B, the 20% decrease in sales resulted in a 46.9% decrease in net income. This also could have been found by taking the initial operating leverage times the 20% decrease: Company A: 20% decreases × 1.74 operating leverage = 34.8% decrease in net income Company B: 20% decreases × 2.47 operating leverage = 49.4% decrease in net income Company A: 20% decreases × 1.74 operating leverage = 34.8% decrease in net income Company B: 20% decreases × 2.47 operating leverage = 49.4% decrease in net income This example also shows why, during periods of decline, companies look for ways to reduce their fixed costs to avoid large percentage reductions in net operating income. Think It Through Moving Costs You are the managerial accountant for a large manufacturing firm. The company has sales that are well above its break-even point, but they have historically carried most of their costs as fixed costs. The outlook for the industry you are in is not positive. How could you move more costs away from fixed costs to put the company in a better financial position if the industry does, in fact, take a downturn? Continuing Application Viking Grocery Stores You might wonder why the grocery industry is not comparable to other big-box retailers such as hardware or large sporting goods stores. Just like other big-box retailers, the grocery industry has a similar product mix, carrying a vast of number of name brands as well as house brands. The main difference, then, is that the profit margin per dollar of sales (i.e., profitability) is smaller than the typical big-box retailer. Also, the inventory turnover and degree of product spoilage is greater for grocery stores. Overall, while the fixed and variable costs are similar to other big-box retailers, a grocery store must sell vast quantities in order to create enough revenue to cover those costs. This is reflected in the business plan. Unlike a manufacturer, a grocery store will have hundreds of products at one time with various levels of margin, all of which will be taken into account in the development of their break-even analysis. Review a business plan developed by Viking Grocery Stores in consideration of opening a new site in Springfield, Missouri to see how a grocery store develops a business plan and break-even based upon multiple products.
introduction_to_sociology
Learning Objectives 15.1 The Sociological Approach to Religion Discuss historical view of religion from a sociological perspective Understand how the major sociological paradigms view religion 15.2 World Religions Explain the differences between various types of religious organizations Understand classifications of religion, like animism, polytheism, monotheism, and atheism Describe several major world religions 15.3 Religion in the United States Give examples of religion as an agent of social change Describe current U.S. trends including megachurches and secularization Introduction to Religion Why do sociologists study religion? For centuries, humankind has sought to understand and explain the “meaning of life.” Many philosophers believe this contemplation and the desire to understand our place in the universe are what differentiate humankind from other species. Religion, in one form or another, has been found in all human societies since human societies first appeared. Archaeological digs have revealed ritual objects, ceremonial burial sites, and other religious artifacts. Social conflict and even wars often result from religious disputes. To understand a culture, sociologists must study its religion. What is religion? Pioneer sociologist Emile Durkheim described it with the ethereal statement that it consists of “things that surpass the limits of our knowledge” (1915). He went on to elaborate: Religion is “a unified system of beliefs and practices relative to sacred things, that is to say set apart and forbidden, beliefs and practices which unite into one single moral community, called a church, all those who adhere to them” (1915). Some people associate religion with places of worship (a synagogue or church), others with a practice (confession or meditation), and still others with a concept that guides their daily lives (like dharma or sin). All of these people can agree that religion is a system of beliefs, values, and practices concerning what a person holds sacred or considers to be spiritually significant. Religion can also serve as a filter for examining other issues in society and other components of a culture. For example, after the terrorist attacks of September 11, 2001, it became important for teachers, church leaders, and the media to educate Americans about Islam to prevent stereotyping and to promote religious tolerance. Sociological tools and methods, such as surveys, polls, interviews, and analysis of historical data, can be applied to the study of religion in a culture to help us better understand the role religion plays in people’s lives and the way it influences society.
[ { "answer": { "ans_choice": 3, "ans_text": "All of the above" }, "bloom": null, "hl_context": "<hl> Functionalists contend that religion serves several functions in society . <hl> Religion , in fact , depends on society for its existence , value , and significance , and vice versa . <hl> From this perspective , religion serves several purposes , like providing answers to spiritual mysteries , offering emotional comfort , and creating a place for social interaction and social control . <hl> While some people think of religion as something individual because religious beliefs can be highly personal , religion is also a social institution . <hl> Social scientists recognize that religion exists as an organized and integrated set of beliefs , behaviors , and norms centered on basic social needs and values . <hl> Moreover , religion is a cultural universal found in all social groups . For instance , in every culture , funeral rites are practiced in some way , although these customs vary between cultures and within religious affiliations . Despite differences , there are common elements in a ceremony marking a person ’ s death , such as announcement of the death , care of the deceased , disposition , and ceremony or ritual . These universals , and the differences in how societies and individuals experience religion , provide rich material for sociological study .", "hl_sentences": "Functionalists contend that religion serves several functions in society . From this perspective , religion serves several purposes , like providing answers to spiritual mysteries , offering emotional comfort , and creating a place for social interaction and social control . Social scientists recognize that religion exists as an organized and integrated set of beliefs , behaviors , and norms centered on basic social needs and values .", "question": { "cloze_format": "Religion serve the role of a social institution in the way that ___.", "normal_format": "In what ways does religion serve the role of a social institution?", "question_choices": [ "Religions have a complex and integrated set of norms. ", "Religious practices and beliefs are related to societal values. ", "Religions often meet several basic needs. ", "All of the above" ], "question_id": "fs-id1417905", "question_text": "In what ways does religion serve the role of a social institution?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 1, "ans_text": "is found in all cultures " }, "bloom": "1", "hl_context": "While some people think of religion as something individual because religious beliefs can be highly personal , religion is also a social institution . Social scientists recognize that religion exists as an organized and integrated set of beliefs , behaviors , and norms centered on basic social needs and values . <hl> Moreover , religion is a cultural universal found in all social groups . <hl> <hl> For instance , in every culture , funeral rites are practiced in some way , although these customs vary between cultures and within religious affiliations . <hl> Despite differences , there are common elements in a ceremony marking a person ’ s death , such as announcement of the death , care of the deceased , disposition , and ceremony or ritual . These universals , and the differences in how societies and individuals experience religion , provide rich material for sociological study .", "hl_sentences": "Moreover , religion is a cultural universal found in all social groups . For instance , in every culture , funeral rites are practiced in some way , although these customs vary between cultures and within religious affiliations .", "question": { "cloze_format": "A cultural universal is something that ___ .", "normal_format": "What is a cultural universal?", "question_choices": [ "addresses all aspects of a group’s behavior ", "is found in all cultures ", "is based on social norms ", "may or may not be of value in meeting social needs" ], "question_id": "fs-id1378609", "question_text": "A cultural universal is something that:" }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 1, "ans_text": "Symbolic interactionism" }, "bloom": "1", "hl_context": "<hl> Rising from the concept that our world is socially constructed , symbolic interactionism studies the symbols and interactions of everyday life . <hl> To interactionists , beliefs and experiences are not sacred unless individuals in a society regard them as sacred . <hl> The Star of David in Judaism , the cross in Christianity , and the crescent and star in Islam are examples of sacred symbols . <hl> Interactionists are interested in what these symbols communicate . Additionally , because interactionists study one-on-one everyday interactions between individuals , a scholar using this approach might ask questions focused on this dynamic . The interaction between religious leaders and practitioners , the role of religion in the banal components of everyday life , and the ways people express religious values in social interactions — all might be topics of study to an interactionist . 15.2 World Religions", "hl_sentences": "Rising from the concept that our world is socially constructed , symbolic interactionism studies the symbols and interactions of everyday life . The Star of David in Judaism , the cross in Christianity , and the crescent and star in Islam are examples of sacred symbols .", "question": { "cloze_format": "The main theoretical perspective that would approach religion from the micro-level, studying how religion impacts an individual’s sense of support and well-being is (the) ___.", "normal_format": "Which of the main theoretical perspectives would approach religion from the micro-level, studying how religion impacts an individual’s sense of support and well-being?", "question_choices": [ "Functionalism", "Symbolic interactionism", "Conflict theory", "Feminism" ], "question_id": "fs-id1384557", "question_text": "Which of the main theoretical perspectives would approach religion from the micro-level, studying how religion impacts an individual’s sense of support and well-being?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 0, "ans_text": "Functional perspective" }, "bloom": "1", "hl_context": "<hl> Functionalists contend that religion serves several functions in society . <hl> <hl> Religion , in fact , depends on society for its existence , value , and significance , and vice versa . <hl> <hl> From this perspective , religion serves several purposes , like providing answers to spiritual mysteries , offering emotional comfort , and creating a place for social interaction and social control . <hl>", "hl_sentences": "Functionalists contend that religion serves several functions in society . Religion , in fact , depends on society for its existence , value , and significance , and vice versa . From this perspective , religion serves several purposes , like providing answers to spiritual mysteries , offering emotional comfort , and creating a place for social interaction and social control .", "question": { "cloze_format": "The ___ is the perspective that most emphasizes the ways in which religion helps to keep the social system running smoothly.", "normal_format": "Which perspective most emphasizes the ways in which religion helps to keep the social system running smoothly?", "question_choices": [ "Functional perspective", "Symbolic interactionist perspective", "Conflict perspective", "Feminist perspective " ], "question_id": "fs-id1441476", "question_text": "Which perspective most emphasizes the ways in which religion helps to keep the social system running smoothly?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 2, "ans_text": "Conflict theory" }, "bloom": null, "hl_context": "<hl> Conflict theorists view religion as an institution that helps maintain patterns of social inequality . <hl> For example , the Vatican has a tremendous amount of wealth , while the average income of Catholic parishioners is small . <hl> According to this perspective , religion has been used to support the “ divine right ” of oppressive monarchs and to justify unequal social structures , like India ’ s caste system . <hl>", "hl_sentences": "Conflict theorists view religion as an institution that helps maintain patterns of social inequality . According to this perspective , religion has been used to support the “ divine right ” of oppressive monarchs and to justify unequal social structures , like India ’ s caste system .", "question": { "cloze_format": "The socialist perspective that most emphasizes the ways in which religion helps to maintain social inequalities within a society is the ___.", "normal_format": "Which socialist perspective most emphasizes the ways in which religion helps to maintain social inequalities within a society?", "question_choices": [ "Functional ", "Symbolic interactionist", "Conflict theory", "Feminist perspective " ], "question_id": "fs-id1452284", "question_text": "Which socialist perspective most emphasizes the ways in which religion helps to maintain social inequalities within a society?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 0, "ans_text": "Position that religion relates to social control, enforcing social norms" }, "bloom": null, "hl_context": "<hl> Conflict theorists view religion as an institution that helps maintain patterns of social inequality . <hl> For example , the Vatican has a tremendous amount of wealth , while the average income of Catholic parishioners is small . <hl> According to this perspective , religion has been used to support the “ divine right ” of oppressive monarchs and to justify unequal social structures , like India ’ s caste system . <hl> <hl> One of the most important functions of religion , from a functionalist perspective , is the opportunities it creates for social interaction and the formation of groups . <hl> It provides social support and social networking , offering a place to meet others who hold similar values and a place to seek help ( spiritual and material ) in times of need . Moreover , it can foster group cohesion and integration . Because religion can be central to many people ’ s concept of themselves , sometimes there is an “ in group ” versus “ out group ” feeling toward other religions in our society or within a particular practice . On an extreme level , the Inquisition , the Salem witch trials , and anti-Semitism are all examples of this dynamic . <hl> Finally , religion promotes social control : It reinforces social norms such as appropriate styles of dress , following the law , and regulating sexual behavior . <hl>", "hl_sentences": "Conflict theorists view religion as an institution that helps maintain patterns of social inequality . According to this perspective , religion has been used to support the “ divine right ” of oppressive monarchs and to justify unequal social structures , like India ’ s caste system . One of the most important functions of religion , from a functionalist perspective , is the opportunities it creates for social interaction and the formation of groups . Finally , religion promotes social control : It reinforces social norms such as appropriate styles of dress , following the law , and regulating sexual behavior .", "question": { "cloze_format": "The functionalist and conflict perspectives share the ___.", "normal_format": "Which of the following do the functionalist and conflict perspectives share?", "question_choices": [ "Position that religion relates to social control, enforcing social norms", "Emphasis on religion as providing social support", "Belief that religion helps explain the mysteries of life", "None of the above" ], "question_id": "fs-id1370186", "question_text": "Which of the following do the functionalist and conflict perspectives share?" }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 1, "ans_text": "capitalism" }, "bloom": null, "hl_context": "<hl> Sociological Research The Protestant Work Ethic in the Information Age Max Weber ( 1904 ) posited that , in Europe in his time , Protestants were more likely than Catholics to value capitalist ideology , believing in hard work and savings . <hl> <hl> He showed that Protestant values directly influenced the rise of capitalism and helped create the modern world order . <hl> Weber thought the emphasis on community in Catholicism versus the emphasis on individual achievement in Protestantism made a difference . His century-old claim that the Protestant work ethic led to the development of capitalism has been one of the most important and controversial topics in the sociology of religion . In fact , scholars have found little merit to his contention when applied to modern society ( Greeley 1989 ) . Whereas Durkheim saw religion as a source of social stability , German sociologist and political economist Max Weber ( 1864 – 1920 ) believed it was a precipitator of social change . He examined the effects of religion on economic activities and noticed that heavily Protestant societies — such as those in the Netherlands , England , Scotland , and Germany — were the most highly developed capitalist societies and that their most successful business leaders were Protestant . <hl> In his writing The Protestant Work Ethic and the Spirit of Capitalism ( 1905 ) , he contends that the Protestant work ethic influenced the development of capitalism . <hl> Weber noted that certain kinds of Protestantism supported the pursuit of material gain by motivating believers to work hard , be successful , and not spend their profits on frivolous things . ( The modern use of “ work ethic ” comes directly from Weber ’ s Protestant ethic , although it has now lost its religious connotations . )", "hl_sentences": "Sociological Research The Protestant Work Ethic in the Information Age Max Weber ( 1904 ) posited that , in Europe in his time , Protestants were more likely than Catholics to value capitalist ideology , believing in hard work and savings . He showed that Protestant values directly influenced the rise of capitalism and helped create the modern world order . In his writing The Protestant Work Ethic and the Spirit of Capitalism ( 1905 ) , he contends that the Protestant work ethic influenced the development of capitalism .", "question": { "cloze_format": "The Protestant work ethic was viewed in terms of its relationship to ___ .", "normal_format": "In terms of which relationship the Protestant work ethic was viewed?", "question_choices": [ "evolution and natural selection", "capitalism", "determinism", "prejudice and discrimination" ], "question_id": "fs-id1434199", "question_text": "The Protestant work ethic was viewed in terms of its relationship to:" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 3, "ans_text": "Methodist and Seventh-day Adventist" }, "bloom": null, "hl_context": "<hl> A denomination is a large , mainstream religious organization , but it does not claim to be official or state sponsored . <hl> It is one religion among many . <hl> For example , Baptist , African Methodist Episcopal , Catholic , and Seventh-day Adventist are all Christian denominations . <hl>", "hl_sentences": "A denomination is a large , mainstream religious organization , but it does not claim to be official or state sponsored . For example , Baptist , African Methodist Episcopal , Catholic , and Seventh-day Adventist are all Christian denominations .", "question": { "cloze_format": "___ are some denominations of the Christian Protestant church.", "normal_format": "What are some denominations of the Christian Protestant church?", "question_choices": [ "Catholic and Jewish", "Jehovah’s Witnesses and Presbyterians", "Scientology and Hare Krishna", "Methodist and Seventh-day Adventist" ], "question_id": "fs-id1566465", "question_text": "What are some denominations of the Christian Protestant church?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 1, "ans_text": "often believes it must split from the larger group to return to important fundamentals" }, "bloom": "3", "hl_context": "<hl> Occasionally , a sect is breakaway group that may be in tension with larger society . <hl> They sometimes claim to be returning to “ the fundamentals ” or to contest the veracity of a particular doctrine . When membership in a sect increases over time , it may grow into a denomination . <hl> Often a sect begins as an offshoot of a denomination , when a group of members believes they should separate from the larger group . <hl>", "hl_sentences": "Occasionally , a sect is breakaway group that may be in tension with larger society . Often a sect begins as an offshoot of a denomination , when a group of members believes they should separate from the larger group .", "question": { "cloze_format": "A sect ___ .", "normal_format": "What is the characteristic of a sect?", "question_choices": [ "has generally grown so large that it needs new buildings and multiple leaders ", "often believes it must split from the larger group to return to important fundamentals", "is another term for a cult", "All of the above" ], "question_id": "fs-id1798422", "question_text": "A sect:" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 2, "ans_text": "ecclesia are state-sponsored and considered an official religion" }, "bloom": "4", "hl_context": "<hl> The term ecclesia , originally referring to a political assembly of citizens in ancient Athens , Greece , now refers to a congregation . <hl> In sociology , the term is used to refer to a religious group that most all members of a society belong to . <hl> It is considered a nationally recognized , or official , religion that holds a religious monopoly and is closely allied with state and secular powers . <hl> The United States does not have an ecclesia by this standard ; in fact , this is the type of religious organization that many of the first colonists came to America to escape . <hl> A denomination is a large , mainstream religious organization , but it does not claim to be official or state sponsored . <hl> It is one religion among many . For example , Baptist , African Methodist Episcopal , Catholic , and Seventh-day Adventist are all Christian denominations .", "hl_sentences": "The term ecclesia , originally referring to a political assembly of citizens in ancient Athens , Greece , now refers to a congregation . It is considered a nationally recognized , or official , religion that holds a religious monopoly and is closely allied with state and secular powers . A denomination is a large , mainstream religious organization , but it does not claim to be official or state sponsored .", "question": { "cloze_format": "The main difference between an ecclesia and a denomination is that ___ .", "normal_format": "What is the main difference between an ecclesia and a denomination?", "question_choices": [ "the number of followers or believers is much larger for denominations", "the geographical location varies for ecclesia versus denominations", "ecclesia are state-sponsored and considered an official religion", "there are no important differences; the terms are interchangeable " ], "question_id": "fs-id1842222", "question_text": "The main difference between an ecclesia and a denomination is:" }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 0, "ans_text": "Scientology and the Hare Krishna" }, "bloom": null, "hl_context": "<hl> Controversy exists over whether some groups are cults , perhaps due in part to media sensationalism over groups like polygamous Mormons or the Peoples Temple followers who died at Jonestown , Guyana . <hl> <hl> Some groups that are controversially labeled as cults today include the Church of Scientology and the Hare Krishna movement . <hl>", "hl_sentences": "Controversy exists over whether some groups are cults , perhaps due in part to media sensationalism over groups like polygamous Mormons or the Peoples Temple followers who died at Jonestown , Guyana . Some groups that are controversially labeled as cults today include the Church of Scientology and the Hare Krishna movement .", "question": { "cloze_format": "Some controversial groups that may be mislabeled as cults include ___.", "normal_format": "What is an example of some controversial groups that may be mislabeled as cults?", "question_choices": [ "Scientology and the Hare Krishna", "the Peoples Temple and Heaven’s Gate", "the Branch Davidians and the Manson Family", "Quakers and Pentecostals " ], "question_id": "fs-id1551769", "question_text": "Some controversial groups that may be mislabeled as cults include:" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 2, "ans_text": "China" }, "bloom": "1", "hl_context": "<hl> In Taoism , the purpose of life is inner peace and harmony . <hl> <hl> Tao is usually translated as “ way ” or “ path . ” The founder of the religion is generally recognized to be a man named Laozi , who lived sometime in the sixth century B . C . E . <hl> <hl> in China . <hl> Taoist beliefs emphasize the virtues of compassion and moderation . <hl> Confucianism was the official religion of China from 200 B . C . E . <hl> until it was officially abolished when communist leadership discouraged religious practice in 1949 . The religion was developed by Kung Fu-Tzu ( Confucius ) , who lived in the sixth and fifth centuries B . C . E . An extraordinary teacher , his lessons — which were about self-discipline , respect for authority and tradition , and jen ( the kind treatment of every person ) — were collected in a book called the Analects .", "hl_sentences": "In Taoism , the purpose of life is inner peace and harmony . Tao is usually translated as “ way ” or “ path . ” The founder of the religion is generally recognized to be a man named Laozi , who lived sometime in the sixth century B . C . E . in China . Confucianism was the official religion of China from 200 B . C . E .", "question": { "cloze_format": "The part of the world where Confucianism and Taoism have been primarily practiced is ___.", "normal_format": "In what part of the world have Confucianism and Taoism been primarily practiced?", "question_choices": [ "India", "Europe", "China", "The Middle East " ], "question_id": "fs-id1388813", "question_text": "In what part of the world have Confucianism and Taoism been primarily practiced?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 2, "ans_text": "shared by Christianity and Islam" }, "bloom": "1", "hl_context": "<hl> The sacred text for Christians is the Bible . <hl> <hl> While Jews , Christians , and Muslims share many of same historical religious stories , their beliefs verge . <hl> In their shared sacred stories , it is suggested that the son of God — a messiah — will return to save God ’ s followers . While Christians believe that he already appeared in the person of Jesus Christ , Jews and Muslims disagree . While they recognize Christ as an important historical figure , their traditions don ’ t believe he ’ s the son of God , and their faiths see the prophecy of the messiah ’ s arrival as not yet fulfilled .", "hl_sentences": "The sacred text for Christians is the Bible . While Jews , Christians , and Muslims share many of same historical religious stories , their beliefs verge .", "question": { "cloze_format": "Many stories in the sacred text of Judaism are ___ .", "normal_format": "What is the characteristic of many stories in the sacred text of Judaism?", "question_choices": [ "referred to as the Apocrypha", "oral traditions only because Judaism has no sacred text", "shared by Christianity and Islam", "no longer part of the Torah" ], "question_id": "fs-id1832749", "question_text": "Many stories in the sacred text of Judaism are:" }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 3, "ans_text": "All of the above" }, "bloom": "1", "hl_context": "Different Christian groups have variations among their sacred texts . For instance , Mormons , an established Christian sect , also use the Book of Mormon , which they believe details other parts of Christian doctrine and Jesus ’ life that aren ’ t included in the Bible . Similarly , the Catholic Bible includes the Apocrypha , a collection that , while part of the 1611 King James translation , is no longer included in Protestant versions of the Bible . <hl> Although monotheistic , Christians often describe their god through three manifestations that they call the Holy Trinity : the father ( God ) , the son ( Jesus ) , and the Holy Spirit . <hl> The Holy Spirit is a term Christians often use to describe religious experience , or how they feel the presence of the sacred in their lives . One foundation of Christian doctrine is the Ten Commandments , which decry acts considered sinful , including theft , murder , and adultery . 15.3 Religion in the United States <hl> Islam is monotheistic religion and it follows the teaching of the prophet Muhammad , born in Mecca , Saudi Arabia , in 570 C . E . <hl> Muhammad is seen only as a prophet , not as a divine being , and he is believed to be the messenger of Allah ( God ) , who is divine . The followers of Islam , whose U . S . population is projected to double in the next 20 years ( Pew Research Forum 2011 ) , are called Muslims . <hl> Islam means “ peace ” and “ submission . ” The sacred text for Muslims is the Qur ’ an ( or Koran ) . <hl> <hl> As with Christianity ’ s Old Testament , many of the Qur ’ an stories are shared with the Jewish faith . <hl> Divisions exist within Islam , but all Muslims are guided by five beliefs or practices , often called “ pillars ” : 1 ) Allah is the only god and Muhammad is his prophet , 2 ) daily prayer , 3 ) helping those in poverty , 4 ) fasting as a spiritual practice , and 5 ) pilgrimage to the holy center of Mecca . Conflict theorists are critical of the way many religions promote the idea that one should be satisfied with existing circumstances because they are divinely ordained . <hl> This power dynamic has been used by Christian institutions for centuries to keep poor people poor , teaching them that they shouldn ’ t be concerned with what they lack because their “ true ” reward ( from a religious perspective ) will come after death . <hl> Conflict theorists also point out that those in power in a religion are often able to dictate practices , rituals , and beliefs through their interpretation of religious texts or via proclaimed direct communication from the divine .", "hl_sentences": "Although monotheistic , Christians often describe their god through three manifestations that they call the Holy Trinity : the father ( God ) , the son ( Jesus ) , and the Holy Spirit . Islam is monotheistic religion and it follows the teaching of the prophet Muhammad , born in Mecca , Saudi Arabia , in 570 C . E . Islam means “ peace ” and “ submission . ” The sacred text for Muslims is the Qur ’ an ( or Koran ) . As with Christianity ’ s Old Testament , many of the Qur ’ an stories are shared with the Jewish faith . This power dynamic has been used by Christian institutions for centuries to keep poor people poor , teaching them that they shouldn ’ t be concerned with what they lack because their “ true ” reward ( from a religious perspective ) will come after death .", "question": { "cloze_format": "Christianity and Islam have in common that ___ .", "normal_format": "What do Christianity and Islam have in common?", "question_choices": [ "Both believe in a single supreme God.", "Both share many of the same stories in their central religious texts.", "Both believe in an afterlife.", "All of the above" ], "question_id": "fs-id1376481", "question_text": "What do Christianity and Islam have in common?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 2, "ans_text": "liberation theology" }, "bloom": "1", "hl_context": "<hl> Liberation theology began as a movement within the Roman Catholic Church in the 1950s and 1960s in Latin America , and it combines Christian principles with political activism . <hl> <hl> It uses the church to promote social change via the political arena , and it is most often seen in attempts to reduce or eliminate social injustice , discrimination , and poverty . <hl> A list of proponents of this kind of social justice ( although some pre-date liberation theory ) could include Francis of Assisi , Leo Tolstoy , Martin Luther King Jr . , and Desmond Tutu . Although begun as a moral reaction against the poverty caused by social injustice in that part of the world , today liberation theology is an international movement that encompasses many churches and denominations . Liberation theologians discuss theology from the point of view of the poor and the oppressed , and some interpret the scriptures as a call to action against poverty and injustice . In Europe and North America , feminist theology has emerged from liberation theology , as a movement to bring social justice to women .", "hl_sentences": "Liberation theology began as a movement within the Roman Catholic Church in the 1950s and 1960s in Latin America , and it combines Christian principles with political activism . It uses the church to promote social change via the political arena , and it is most often seen in attempts to reduce or eliminate social injustice , discrimination , and poverty .", "question": { "cloze_format": "Social scientists refer to the use of a church to combat social injustice in the political realm as ___.", "normal_format": "What do social scientists call the use of a church to combat social injustice in the political realm?", "question_choices": [ "the protestant work ethic", "conflict management", "liberation theology", "justice work " ], "question_id": "fs-id2314402", "question_text": "Social scientists refer to the use of a church to combat social injustice in the political realm as:" }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 3, "ans_text": "large arenas where services are held" }, "bloom": null, "hl_context": "<hl> A megachurch is a Christian church that has a very large congregation averaging more than 2,000 people who attend regular weekly services . <hl> As of 2009 , the largest megachurch in the United States was in Houston Texas , boasting an average weekly attendance of more than 43,000 ( Bogan 2009 ) . Megachurches exist in other parts of the world , especially in South Korea , Brazil , and several African countries , but the rise of the megachurch in the United States is a fairly recent phenomenon that has developed primarily in California , Florida , Georgia , and Texas . Since 1970 the number of megachurches in this country has grown from about 50 to more than 1,000 , most of which are attached to the Southern Baptist denomination ( Bogan 2009 ) . Approximately 6 million people are members of these churches ( Bird and Thumma 2011 ) . <hl> The architecture of these church buildings often resembles a sport or concert arena . <hl> The church may include jumbotrons ( large-screen televisual technology usually used in sports arenas to show close-up shots of an event ) . Worship services feature contemporary music with drums and electric guitars and use state-of-the-art sound equipment . The buildings sometimes include food courts , sports and recreation facilities , and bookstores . Services such as child care and mental health counseling are often offered .", "hl_sentences": "A megachurch is a Christian church that has a very large congregation averaging more than 2,000 people who attend regular weekly services . The architecture of these church buildings often resembles a sport or concert arena .", "question": { "cloze_format": "Megachurches tend to have ___ .", "normal_format": "What do megachurches tend to have?", "question_choices": [ "a variety of male and female clergy", "numerous buildings in which to meet", "high attendance for only a limited time", "large arenas where services are held" ], "question_id": "fs-id2080167", "question_text": "Megachurches tend to have:" }, "references_are_paraphrase": null } ]
15
15.1 The Sociological Approach to Religion From the Latin religio (respect for what is sacred) and religare (to bind, in the sense of an obligation), the term religion describes various systems of belief and practice concerning what people determine to be sacred or spiritual (Fasching and deChant 2001; Durkheim 1915). Throughout history, and in societies across the world, leaders have used religious narratives, symbols, and traditions in an attempt to give more meaning to life and understand the universe. Some form of religion is found in every known culture, and it is usually practiced in a public way by a group. The practice of religion can include feasts and festivals, God or gods, marriage and funeral services, music and art, meditation or initiation, sacrifice or service, and other aspects of culture. While some people think of religion as something individual because religious beliefs can be highly personal, religion is also a social institution. Social scientists recognize that religion exists as an organized and integrated set of beliefs, behaviors, and norms centered on basic social needs and values. Moreover, religion is a cultural universal found in all social groups. For instance, in every culture, funeral rites are practiced in some way, although these customs vary between cultures and within religious affiliations. Despite differences, there are common elements in a ceremony marking a person’s death, such as announcement of the death, care of the deceased, disposition, and ceremony or ritual. These universals, and the differences in how societies and individuals experience religion, provide rich material for sociological study. In studying religion, sociologists distinguish between what they term the experience, beliefs, and rituals of a religion. Religious experience refers to the conviction or sensation that one is connected to “the divine.” This type of communion might be experienced when people are praying or meditating. Religious beliefs are specific ideas that members of a particular faith hold to be true, such as that Jesus Christ was the son of God, or believing in reincarnation. Another illustration of religious beliefs is that different religions adhere to certain stories of world creation. Religious rituals are behaviors or practices that are either required or expected of the members of a particular group, such as bar mitzvah or confession (Barkan and Greenwood 2003). The History of Religion as a Sociological Concept In the wake of 19th century European industrialization and secularization, three social theorists attempted to examine the relationship between religion and society: Émile Durkheim, Max Weber, and Karl Marx. They are among the founding thinkers of modern sociology. As stated earlier, French sociologist Émile Durkheim (1858–1917) defined religion as a “unified system of beliefs and practices relative to sacred things” (1915). To him, sacred meant extraordinary—something that inspired wonder and which seemed connected to the concept of “the divine.” Durkheim argued that “religion happens” in society when there is a separation between the profane (ordinary life) and the sacred (1915). A rock, for example, isn’t sacred or profane as it exists. But if someone makes it into a headstone, or another person uses it for landscaping, it takes on different meanings—one sacred, one profane. Durkheim is generally considered the first sociologist who analyzed religion in terms of its societal impact. Above all, Durkheim believed that religion is about community: It binds people together (social cohesion), promotes behavior consistency (social control), and offers strength for people during life’s transitions and tragedies (meaning and purpose). By applying the methods of natural science to the study of society, he held that the source of religion and morality is the collective mind-set of society and that the cohesive bonds of social order result from common values in a society. He contended that these values need to be maintained to maintain social stability. But what would happen if religion were to decline? This question led Durkheim to posit that religion is not just a social creation but something that represents the power of society: When people celebrate sacred things, they celebrate the power of their society. By this reasoning, even if traditional religion disappeared, society wouldn’t necessarily dissolve. Whereas Durkheim saw religion as a source of social stability, German sociologist and political economist Max Weber (1864–1920) believed it was a precipitator of social change. He examined the effects of religion on economic activities and noticed that heavily Protestant societies—such as those in the Netherlands, England, Scotland, and Germany—were the most highly developed capitalist societies and that their most successful business leaders were Protestant. In his writing The Protestant Work Ethic and the Spirit of Capitalism (1905), he contends that the Protestant work ethic influenced the development of capitalism. Weber noted that certain kinds of Protestantism supported the pursuit of material gain by motivating believers to work hard, be successful, and not spend their profits on frivolous things. (The modern use of “work ethic” comes directly from Weber’s Protestant ethic, although it has now lost its religious connotations.) Sociological Research The Protestant Work Ethic in the Information Age Max Weber (1904) posited that, in Europe in his time, Protestants were more likely than Catholics to value capitalist ideology, believing in hard work and savings. He showed that Protestant values directly influenced the rise of capitalism and helped create the modern world order. Weber thought the emphasis on community in Catholicism versus the emphasis on individual achievement in Protestantism made a difference. His century-old claim that the Protestant work ethic led to the development of capitalism has been one of the most important and controversial topics in the sociology of religion. In fact, scholars have found little merit to his contention when applied to modern society (Greeley 1989). What does the concept of work ethic mean today? The work ethic in the information age has been affected by tremendous cultural and social change, just as workers in the mid- to late 19th century were influenced by the wake of the Industrial Revolution. Factory jobs tend to be simple and uninvolved and require very little thinking or decision making on the part of the worker. Today, the work ethic of the modern workforce has been transformed, as more thinking and decision making is required. Employees also seek autonomy and fulfillment in their jobs, not just wages. Higher levels of education have become necessary, as well as people management skills and access to the most recent information on any given topic. The information age has increased the rapid pace of production expected in many jobs. On the other hand, the “McDonaldization” of the United States, in which many service industries, such as the fast-food industry, have established routinized roles and tasks, has resulted in a “discouragement” of the work ethic. In jobs where roles and tasks are highly prescribed, workers have no opportunity to make decisions. They are considered replaceable commodities as opposed to valued employees. During times of recession, these service jobs may be the only employment possible for younger individuals or those with low-level skills. The pay, working conditions, and robotic nature of the tasks dehumanizes the workers and strips them of incentives for doing quality work. Working hard also doesn’t seem to have any relationship with Catholic or Protestant religious beliefs anymore, or those of other religions; information age workers expect talent and hard work to be rewarded by material gain and career advancement. German philosopher, journalist, and revolutionary socialist Karl Marx (1818–1883) also studied the social impact of religion. He believed religion reflects the social stratification of society and that it maintains inequality and perpetuates the status quo. For him, religion was just an extension of working-class (proletariat) economic suffering. He famously argued that religion is “is the opium of the people” (1844). For Durkheim, Weber, and Marx, who were reacting to the great social and economic upheaval of the late 19th century and early 20th century in Europe, religion was an integral part of society. For Durkheim, religion was a force for cohesion that helped bind the members of society to the group, while Weber believed religion could be understood as something separate from society. Marx considered religion inseparable from the economy and the worker. Religion could not be understood apart from the capitalist society that perpetuated inequality. Despite their different views, these social theorists all believed in the centrality of religion to society. Theoretical Perspectives on Religion Modern-day sociologists often apply one of three major theoretical perspectives. These views offer different lenses through which to study and understand society: functionalism, symbolic interactionism, and conflict theory. Let’s explore how scholars applying these paradigms understand religion. Functionalism Functionalists contend that religion serves several functions in society. Religion, in fact, depends on society for its existence, value, and significance, and vice versa. From this perspective, religion serves several purposes, like providing answers to spiritual mysteries, offering emotional comfort, and creating a place for social interaction and social control. In providing answers, religion defines the spiritual world and spiritual forces, including divine beings. For example, it helps answer questions like “How was the world created?” “Why do we suffer?” “Is there a plan for our lives?” and “Is there an afterlife?” As another function, religion provides emotional comfort in times of crisis. Religious rituals bring order, comfort, and organization through shared familiar symbols and patterns of behavior. One of the most important functions of religion, from a functionalist perspective, is the opportunities it creates for social interaction and the formation of groups. It provides social support and social networking, offering a place to meet others who hold similar values and a place to seek help (spiritual and material) in times of need. Moreover, it can foster group cohesion and integration. Because religion can be central to many people’s concept of themselves, sometimes there is an “in group” versus “out group” feeling toward other religions in our society or within a particular practice. On an extreme level, the Inquisition, the Salem witch trials, and anti-Semitism are all examples of this dynamic. Finally, religion promotes social control: It reinforces social norms such as appropriate styles of dress, following the law, and regulating sexual behavior. Conflict Theory Conflict theorists view religion as an institution that helps maintain patterns of social inequality. For example, the Vatican has a tremendous amount of wealth, while the average income of Catholic parishioners is small. According to this perspective, religion has been used to support the “divine right” of oppressive monarchs and to justify unequal social structures, like India’s caste system. Conflict theorists are critical of the way many religions promote the idea that one should be satisfied with existing circumstances because they are divinely ordained. This power dynamic has been used by Christian institutions for centuries to keep poor people poor, teaching them that they shouldn’t be concerned with what they lack because their “true” reward (from a religious perspective) will come after death. Conflict theorists also point out that those in power in a religion are often able to dictate practices, rituals, and beliefs through their interpretation of religious texts or via proclaimed direct communication from the divine. The feminist perspective is a conflict theory view that focuses specifically on gender inequality. In terms of religion, feminist theorists assert that, although women are typically the ones to socialize children into a religion, they have traditionally held very few positions of power within religions. A few religions and religious denominations are more gender equal, but male dominance remains the norm of most. Sociological Research Rational Choice Theory: Can Economic Theory Be Applied to Religion? How do people decide which religion to follow, if any? How does one pick a church or decide which denomination “fits” best? Rational choice theory (RCT) is one way social scientists have attempted to explain these behaviors. The theory proposes that people are self-interested, though not necessarily selfish, and that people make rational choices—choices that can reasonably be expected to maximize positive outcomes while minimizing negative outcomes. Sociologists Roger Finke and Rodney Stark (1988) first considered the use of RCT to explain some aspects of religious behavior, with the assumption that there is a basic human need for religion in terms of providing belief in a supernatural being, a sense of meaning in life, and belief in life after death. Religious explanations of these concepts are presumed to be more satisfactory than scientific explanations, which may help to account for the continuation of strong religious connectedness in countries such as the United States, despite predictions of some competing theories for a great decline in religious affiliation due to modernization and religious pluralism. Another assumption of RCT is that religious organizations can be viewed in terms of “costs” and “rewards.” Costs are not only monetary requirements, but also include the time, effort, and commitment demands of any particular religious organization. Rewards are the intangible benefits in terms of belief and satisfactory explanations about life, death, and the supernatural, as well as social rewards from membership. RCT proposes that, in a pluralistic society with many religious options, religious organizations will compete for members, and people will choose between different churches or denominations in much the same way they select other consumer goods, balancing costs and rewards in a rational manner. In this framework, RCT also explains the development and decline of churches, denominations, sects, and even cults; this limited part of the very complex RCT theory is the only aspect well supported by research data. Critics of RCT argue that it doesn’t fit well with human spiritual needs, and many sociologists disagree that the costs and rewards of religion can even be meaningfully measured or that individuals use a rational balancing process regarding religious affiliation. The theory doesn’t address many aspects of religion that individuals may consider essential (such as faith) and further fails to account for agnostics and atheists who don’t seem to have a similar need for religious explanations. Critics also believe this theory overuses economic terminology and structure, and point out that terms such as “rational” and “reward” are unacceptably defined by their use; they would argue that the theory is based on faulty logic and lacks external, empirical support. A scientific explanation for why something occurs can’t reasonably be supported by the fact that it does occur. RCT is widely used in economics and to a lesser extent in criminal justice, but the application of RCT in explaining the religious beliefs and behaviors of people and societies is still being debated in sociology today. Symbolic Interactionism Rising from the concept that our world is socially constructed, symbolic interactionism studies the symbols and interactions of everyday life. To interactionists, beliefs and experiences are not sacred unless individuals in a society regard them as sacred. The Star of David in Judaism, the cross in Christianity, and the crescent and star in Islam are examples of sacred symbols. Interactionists are interested in what these symbols communicate. Additionally, because interactionists study one-on-one everyday interactions between individuals, a scholar using this approach might ask questions focused on this dynamic. The interaction between religious leaders and practitioners, the role of religion in the banal components of everyday life, and the ways people express religious values in social interactions—all might be topics of study to an interactionist. 15.2 World Religions The major religions of the world (Hinduism, Buddhism, Islam, Confucianism, Christianity, Taoism, and Judaism) differ in many respects, including how each religion is organized and the belief system each upholds. Other differences include the nature of belief in a higher power, the history of how the world and the religion began, and the use of sacred texts and objects. Types of Religious Organizations Religions organize themselves—their institutions, practitioners, and structures—in a variety of fashions. For instance, when the Roman Catholic Church emerged, it borrowed many of its organizational principles from the ancient Roman military, turning senators into cardinals, for example. Sociologists use different terms, like ecclesia, denomination, and sect, to define these types of organizations. Scholars are also aware that these definitions are not static. Most religions transition through different organizational phases. For example, Christianity began as a cult, transformed into a sect, and today exists as an ecclesia. Cults , like sects, are new religious groups. In modern America this term often carries pejorative connotations. However, almost all religions began as cults and gradually progressed to levels of greater size and organization. The term cult is sometimes used interchangeably with the term new religious movement (NRM). In its pejorative use, these groups are often disparaged as being secretive, highly controlling of members’ lives, and dominated by a single, charismatic leader. Controversy exists over whether some groups are cults, perhaps due in part to media sensationalism over groups like polygamous Mormons or the Peoples Temple followers who died at Jonestown, Guyana. Some groups that are controversially labeled as cults today include the Church of Scientology and the Hare Krishna movement. A sect  is a small and relatively new group. Most of the well-known Christian denominations in the United States today began as sects. For example, the Methodists and Baptists protested against their parent Anglican Church in England, just as Henry VIII protested against the Catholic Church by forming the Anglican Church. From “protest” comes the term Protestant. Occasionally, a sect is breakaway group that may be in tension with larger society. They sometimes claim to be returning to “the fundamentals” or to contest the veracity of a particular doctrine. When membership in a sect increases over time, it may grow into a denomination. Often a sect begins as an offshoot of a denomination, when a group of members believes they should separate from the larger group. Some sects dissolve without growing into denominations. Sociologists call these established sects . Established sects, such as the Amish or Jehovah’s Witnesses fall halfway between sect and denomination on the ecclesia–cult continuum because they have a mixture of sect-like and denomination-like characteristics. A denomination is a large, mainstream religious organization, but it does not claim to be official or state sponsored. It is one religion among many. For example, Baptist, African Methodist Episcopal, Catholic, and Seventh-day Adventist are all Christian denominations. The term ecclesia , originally referring to a political assembly of citizens in ancient Athens, Greece, now refers to a congregation. In sociology, the term is used to refer to a religious group that most all members of a society belong to. It is considered a nationally recognized, or official, religion that holds a religious monopoly and is closely allied with state and secular powers. The United States does not have an ecclesia by this standard; in fact, this is the type of religious organization that many of the first colonists came to America to escape. One way to remember these religious organizational terms is to think of cults, sects, denominations, and ecclesia representing a continuum, with increasing influence on society, where cults are least influential and ecclesia are most influential. Types of Religions Scholars from a variety of disciplines have strived to classify religions. One widely accepted categorization that helps people understand different belief systems considers what or who people worship (if anything). Using this method of classification, religions might fall into one of these basic categories, as shown in Table 15.1 . Religious Classification What/Who Is Divine Example Polytheism Multiple gods Ancient Greeks and Romans Monotheism Single god Judaism, Islam Atheism No deities Atheism Animism Nonhuman beings (animals, plants, natural world) Indigenous nature worship (Shinto) Totemism Human-natural being connection Ojibwa (Native American) Table 15.1 One way scholars have categorized religions is by classifying what or who they hold to be divine. Note that some religions may be practiced—or understood—in various categories. For instance, the Christian notion of the Holy Trinity (God, Jesus, Holy Spirit) defies the definition of monotheism to some scholars. Similarly, many Westerners view the multiple manifestations of Hinduism’s godhead as polytheistic, while Hindus might describe those manifestations are a monotheistic parallel to the Christian Trinity. It is also important to note that every society also has nonbelievers, such as atheists, who do not believe in a divine being or entity, and agnostics, who hold that ultimate reality (such as God) is unknowable. While typically not an organized group, atheists and agnostics represent a significant portion of the population. It is important to recognize that being a nonbeliever in a divine entity does not mean the individual subscribes to no morality. Indeed, many Nobel Peace Prize winners and other great humanitarians over the centuries would have classified themselves as atheists or agnostics. The World’s Religions Religions have emerged and developed across the world. Some have been short-lived, while others have persisted and grown. In this section, we will explore seven of the world’s major religions. Hinduism The oldest religion in the world, Hinduism originated in the Indus River Valley about 4,500 years ago in what is now modern-day northwest India and Pakistan. It arose contemporaneously with ancient Egyptian and Mesopotamian cultures. With roughly 1 billion followers, Hinduism is the third-largest of the world’s religions. Hindus believe in a divine power that can manifest as different entities. Three main incarnations—Brahma, Vishnu, and Shiva—are sometimes compared to the manifestations of the divine in the Christian Trinity. Multiple sacred texts, collectively called the Vedas, contain hymns and rituals from ancient India and are mostly written in Sanskrit. Hindus generally believe in a set of principles called dharma, which refer to one’s duty in the world that corresponds with “right” actions. Hindus also believe in karma, or the notion that spiritual ramifications of one’s actions are balanced cyclically in this life or a future life. Buddhism Buddhism was founded by Siddhartha Gautama around 500 B.C.E. Siddhartha was said to have given up a comfortable, upper-class life to follow one of poverty and spiritual devotion. At the age of 35, he famously meditated under a sacred fig tree and vowed not to rise before he achieved enlightenment ( bodhi ). After this experience, he became known as Buddha, or “enlightened one.” Followers were drawn to Buddha’s teachings and the practice of meditation, and he later established a monastic order. Buddha’s teachings encourage Buddhists to lead a moral life by accepting the four Noble Truths: 1) life is suffering, 2) suffering arises from attachment to desires, 3) suffering ceases when attachment to desires ceases, and 4) freedom from suffering is possible by following the “middle way.” The concept of “middle way” is central to Buddhist thinking, which encourages people to live in the present and to practice acceptance of others (Smith 1991). Buddhism also tends to deemphasize the role of a godhead, instead stressing the importance of personal responsibility (Craig 2002). Confucianism Confucianism was the official religion of China from 200 B.C.E. until it was officially abolished when communist leadership discouraged religious practice in 1949. The religion was developed by Kung Fu-Tzu (Confucius), who lived in the sixth and fifth centuries B.C.E. An extraordinary teacher, his lessons—which were about self-discipline, respect for authority and tradition, and jen (the kind treatment of every person)—were collected in a book called the Analects . Some religious scholars consider Confucianism more of a social system than a religion because it focuses on sharing wisdom about moral practices but doesn’t involve any type of specific worship; nor does it have formal objects. In fact, its teachings were developed in context of problems of social anarchy and a near-complete deterioration of social cohesion. Dissatisfied with the social solutions put forth, Kung Fu-Tzu developed his own model of religious morality to help guide society (Smith 1991). Taoism In Taoism, the purpose of life is inner peace and harmony. Tao is usually translated as “way” or “path.” The founder of the religion is generally recognized to be a man named Laozi, who lived sometime in the sixth century B.C.E. in China. Taoist beliefs emphasize the virtues of compassion and moderation. The central concept of tao can be understood to describe a spiritual reality, the order of the universe, or the way of modern life in harmony with the former two. The ying-yang symbol and the concept of polar forces are central Taoist ideas (Smith 1991). Some scholars have compared this Chinese tradition to its Confucian counterpart by saying that “whereas Confucianism is concerned with day-to-day rules of conduct, Taoism is concerned with a more spiritual level of being” (Feng and English 1972). Judaism After their Exodus from Egypt in the 13th century B.C.E., Jews, a nomadic society, became monotheistic, worshipping only one God. The Jews’ covenant, or promise of a special relationship with Yahweh (God), is an important element of Judaism, and their sacred text is the Torah, which Christians also follow as the first five books of the Bible. Talmud refers to a collection of sacred Jewish oral interpretation of the Torah. Jews emphasize moral behavior and action in this world as opposed to beliefs or personal salvation in the next world. Islam Islam is monotheistic religion and it follows the teaching of the prophet Muhammad, born in Mecca, Saudi Arabia, in 570 C.E. Muhammad is seen only as a prophet, not as a divine being, and he is believed to be the messenger of Allah (God), who is divine. The followers of Islam, whose U.S. population is projected to double in the next 20 years (Pew Research Forum 2011), are called Muslims. Islam means “peace” and “submission.” The sacred text for Muslims is the Qur’an (or Koran). As with Christianity’s Old Testament, many of the Qur’an stories are shared with the Jewish faith. Divisions exist within Islam, but all Muslims are guided by five beliefs or practices, often called “pillars”: 1) Allah is the only god and Muhammad is his prophet, 2) daily prayer, 3) helping those in poverty, 4) fasting as a spiritual practice, and 5) pilgrimage to the holy center of Mecca. Christianity Today the largest religion in the world, Christianity began 2,000 years ago in Palestine, with Jesus of Nazareth, a charismatic leader who taught his followers about caritas (charity) or treating others as you would like to be treated yourself. The sacred text for Christians is the Bible. While Jews, Christians, and Muslims share many of same historical religious stories, their beliefs verge. In their shared sacred stories, it is suggested that the son of God—a messiah—will return to save God’s followers. While Christians believe that he already appeared in the person of Jesus Christ, Jews and Muslims disagree. While they recognize Christ as an important historical figure, their traditions don’t believe he’s the son of God, and their faiths see the prophecy of the messiah’s arrival as not yet fulfilled. Different Christian groups have variations among their sacred texts. For instance, Mormons, an established Christian sect, also use the Book of Mormon, which they believe details other parts of Christian doctrine and Jesus’ life that aren’t included in the Bible. Similarly, the Catholic Bible includes the Apocrypha, a collection that, while part of the 1611 King James translation, is no longer included in Protestant versions of the Bible. Although monotheistic, Christians often describe their god through three manifestations that they call the Holy Trinity: the father (God), the son (Jesus), and the Holy Spirit. The Holy Spirit is a term Christians often use to describe religious experience, or how they feel the presence of the sacred in their lives. One foundation of Christian doctrine is the Ten Commandments, which decry acts considered sinful, including theft, murder, and adultery. 15.3 Religion in the United States In examining the state of religion in the United States today, we see the complexity of religious life in our society, plus emerging trends like the rise of the megachurch, secularization, and the role of religion in social change. Religion and Social Change Religion has historically been an impetus to social change. The translation of sacred texts into everyday, non-scholarly language empowered people to shape their religions. Disagreements between religious groups and instances of religious persecution have led to wars and genocides. The United States is no stranger to religion as an agent of social change. In fact, our nation’s first European arrivals were acting largely on religious convictions when they were compelled to settle in America. Liberation Theology Liberation theology began as a movement within the Roman Catholic Church in the 1950s and 1960s in Latin America, and it combines Christian principles with political activism. It uses the church to promote social change via the political arena, and it is most often seen in attempts to reduce or eliminate social injustice, discrimination, and poverty. A list of proponents of this kind of social justice (although some pre-date liberation theory) could include Francis of Assisi, Leo Tolstoy, Martin Luther King Jr., and Desmond Tutu. Although begun as a moral reaction against the poverty caused by social injustice in that part of the world, today liberation theology is an international movement that encompasses many churches and denominations. Liberation theologians discuss theology from the point of view of the poor and the oppressed, and some interpret the scriptures as a call to action against poverty and injustice. In Europe and North America, feminist theology has emerged from liberation theology, as a movement to bring social justice to women. Social Policy and Debate Religious Leaders and the Rainbow of Gay Pride What happens when a religious leader officiates a gay marriage against denomination policies? What about when that same minister defends the action in part by coming out and making her own lesbian relationship known to the church? In the case of the Reverend Amy DeLong, it meant a church trial. Some leaders in her denomination assert that homosexuality is incompatible with their faith, while others feel this type of discrimination has no place in a modern church (Barrick 2011). As the LBGT community increasingly advocates for, and earns, basic civil rights, how will religious communities respond? Many religious groups have traditionally discounted LBGT sexualities as “wrong.” However, these organizations have moved closer to respecting human rights by, for example, increasingly recognizing females as an equal gender. The Roman Catholic Church drew controversial attention to this issue in 2010 when the Vatican secretary of state suggested homosexuality was in part to blame for pedophilic sexual abuse scandals that have plagued the church (Beck 2010). Because numerous studies have shown there to be no relationship between homosexuality and pedophilia, nor a higher incidence of pedophilia among homosexuals than among heterosexuals (Beck 2010), the Vatican’s comments seem suspect. No matter the situation, most religions have a tenuous (at best) relationship with practitioners and leaders in the gay community. As one of the earliest Christian denominations to break barriers by ordaining women to serve as pastors, will Amy DeLong’s United Methodist denomination also be a leader in LBGT rights within Christian churchgoing society? Megachurches A megachurch is a Christian church that has a very large congregation averaging more than 2,000 people who attend regular weekly services. As of 2009, the largest megachurch in the United States was in Houston Texas, boasting an average weekly attendance of more than 43,000 (Bogan 2009). Megachurches exist in other parts of the world, especially in South Korea, Brazil, and several African countries, but the rise of the megachurch in the United States is a fairly recent phenomenon that has developed primarily in California, Florida, Georgia, and Texas. Since 1970 the number of megachurches in this country has grown from about 50 to more than 1,000, most of which are attached to the Southern Baptist denomination (Bogan 2009). Approximately 6 million people are members of these churches (Bird and Thumma 2011). The architecture of these church buildings often resembles a sport or concert arena. The church may include jumbotrons (large-screen televisual technology usually used in sports arenas to show close-up shots of an event). Worship services feature contemporary music with drums and electric guitars and use state-of-the-art sound equipment. The buildings sometimes include food courts, sports and recreation facilities, and bookstores. Services such as child care and mental health counseling are often offered. Typically, a single, highly charismatic pastor leads the megachurch; at present, all are male. Some megachurches and their preachers have a huge television presence, and viewers all around the country watch and respond to their shows and fundraising. Besides size, U.S. megachurches share other traits, including conservative theology, evangelism, use of technology and social networking (Facebook, Twitter, podcasts, blogs), hugely charismatic leaders, few financial struggles, multiple sites, and predominantly white membership. They list their main focuses as youth activities, community service, and study of the Scripture (Hartford Institute for Religion Research b). Critics of megachurches believe they are too large to promote close relationships among fellow church members or the pastor, as could occur in smaller houses of worship. Supporters note that, in addition to the large worship services, congregations generally meet in small groups and some megachurches have informal events throughout the week to allow for community-building (Hartford Institute for Religion Research a). Secularization Historical sociologists Émile Durkheim, Max Weber, and Karl Marx and psychoanalyst Sigmund Freud anticipated secularization, claiming that the modernization of society would bring about a decrease in the influence of religion. Weber believed membership in distinguished clubs would outpace membership in Protestant sects as a way for people to gain authority or respect. Conversely, some people contend that secularization is a root cause of many social problems, such as divorce, drug use, and educational downturn. Presidential contender Michele Bachmann even linked Hurricane Irene and the 2011 earthquake felt in Washington D.C. to politicians’ failure to listen to God (Ward 2011). While some scholars see the United States becoming increasingly secular, others observe a rise in fundamentalism. Compared to other democratic, industrialized countries, the U.S. is generally perceived to be a fairly religious nation. Whereas 65 percent of Americans in a 2009 Gallup survey said religion was an important part of their daily lives, the numbers were lower in Spain (49 percent), Canada (42 percent), France (30 percent), the United Kingdom (27 percent), and Sweden (17 percent) (Crabtree and Pelham 2009). Secularization interests social observers because it entails a pattern of change in a fundamental social institution. Sociology in the Real World Thank God for That Touchdown: Separation of Church and State Imagine three public universities with football games scheduled on Saturday. At University A, a group of students in the stands who share the same faith decide to form a circle amid the spectators to pray for the team. For 15 minutes, people in the circle share their prayers aloud among their group. At University B, the team ahead at halftime decides to join together in prayer, giving thanks and seeking support from God. This lasts for the first 10 minutes of halftime on the sidelines of the field while spectators watch. At University C, the game program includes, among its opening moments, two minutes set aside for the team captain to share a prayer of his choosing with spectators. In the tricky area of separation of church and state, which of these actions is allowed and which is forbidden? In these three fictional scenarios, the last example is against the law while the first two situations are perfectly acceptable. In the United States, a nation founded on the principles of religious freedom (many settlers were escaping religious persecution in Europe), how stringently do we adhere to this ideal? How well do we respect people’s right to practice any belief system of their choosing? The answer just might depend on what religion you practice. In 2003, for example, a lawsuit escalated in Alabama regarding a monument to the Ten Commandments in a public building. In response, a poll was conducted by USA Today , CNN, and Gallup. Among the findings: 70 percent of people approved of a Christian Ten Commandments monument in public, while only 33 percent approved of a monument to the Islamic Qur’an in the same space. Similarly, survey respondents showed a 64 percent approval of social programs run by Christian organizations, but only 41 percent approved of the same programs run by Muslim groups (Newport 2003). These statistics suggest that, for most Americans, freedom of religion is less important than the religion under discussion. And this is precisely the point made by those who argue for separation of church and state. According to their contention, any state-sanctioned recognition of religion suggests endorsement of one belief system at the expense of all others—contradictory to the idea of freedom of religion. So what violates separation of church and state and what is acceptable? A myriad of lawsuits continue to contribute to the answer. In the case of the three fictional examples above, the issue of spontaneity is key, as is the existence (or lack thereof) of planning on the part of event organizers. The next time you’re at a state event—political, public school, community—and the topic of religion comes up, consider where it falls in this debate.
anatomy_and_physiology
Chapter Objectives After studying this chapter, you will be able to: Describe the composition of urine Label structures of the urinary system Characterize the roles of each of the parts of the urinary system Illustrate the macroscopic and microscopic structures of the kidney Trace the flow of blood through the kidney Outline how blood is filtered in the kidney nephron Provide symptoms of kidney failure List some of the solutes filtered, secreted, and reabsorbed in different parts of the nephron Describe the role of a portal system in the kidney Explain how urine osmolarity is hormonally regulated Describe the regulation of major ions by the kidney Summarize the role of the kidneys in maintaining acid–base balance Introduction The urinary system has roles you may be well aware of: cleansing the blood and ridding the body of wastes probably come to mind. However, there are additional, equally important functions played by the system. Take for example, regulation of pH, a function shared with the lungs and the buffers in the blood. Additionally, the regulation of blood pressure is a role shared with the heart and blood vessels. What about regulating the concentration of solutes in the blood? Did you know that the kidney is important in determining the concentration of red blood cells? Eighty-five percent of the erythropoietin (EPO) produced to stimulate red blood cell production is produced in the kidneys. The kidneys also perform the final synthesis step of vitamin D production, converting calcidiol to calcitriol, the active form of vitamin D. If the kidneys fail, these functions are compromised or lost altogether, with devastating effects on homeostasis. The affected individual might experience weakness, lethargy, shortness of breath, anemia, widespread edema (swelling), metabolic acidosis, rising potassium levels, heart arrhythmias, and more. Each of these functions is vital to your well-being and survival. The urinary system, controlled by the nervous system, also stores urine until a convenient time for disposal and then provides the anatomical structures to transport this waste liquid to the outside of the body. Failure of nervous control or the anatomical structures leading to a loss of control of urination results in a condition called incontinence. This chapter will help you to understand the anatomy of the urinary system and how it enables the physiologic functions critical to homeostasis. It is best to think of the kidney as a regulator of plasma makeup rather than simply a urine producer. As you read each section, ask yourself this question: “What happens if this does not work?” This question will help you to understand how the urinary system maintains homeostasis and affects all the other systems of the body and the quality of one’s life. Interactive Link Watch this video from the Howard Hughes Medical Institute for an introduction to the urinary system.
[ { "answer": { "ans_choice": 1, "ans_text": "polyuria" }, "bloom": null, "hl_context": "Urine volume varies considerably . The normal range is one to two liters per day ( Table 25.2 ) . The kidneys must produce a minimum urine volume of about 500 mL / day to rid the body of wastes . Output below this level may be caused by severe dehydration or renal disease and is termed oliguria . The virtual absence of urine production is termed anuria . <hl> Excessive urine production is polyuria , which may be due to diabetes mellitus or diabetes insipidus . <hl> In diabetes mellitus , blood glucose levels exceed the number of available sodium-glucose transporters in the kidney , and glucose appears in the urine . The osmotic nature of glucose attracts water , leading to its loss in the urine . In the case of diabetes insipidus , insufficient pituitary antidiuretic hormone ( ADH ) release or insufficient numbers of ADH receptors in the collecting ducts means that too few water channels are inserted into the cell membranes that line the collecting ducts of the kidney . Insufficient numbers of water channels ( aquaporins ) reduce water absorption , resulting in high volumes of very dilute urine .", "hl_sentences": "Excessive urine production is polyuria , which may be due to diabetes mellitus or diabetes insipidus .", "question": { "cloze_format": "Diabetes insipidus or diabetes mellitus would most likely be indicated by ________.", "normal_format": "What would diabetes insipidus or diabetes mellitus most likely be indicated by?", "question_choices": [ "anuria", "polyuria", "oliguria", "none of the above" ], "question_id": "fs-id2378375", "question_text": "Diabetes insipidus or diabetes mellitus would most likely be indicated by ________." }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 2, "ans_text": "byproducts of red blood cell breakdown" }, "bloom": "1", "hl_context": "Urinalysis ( urine analysis ) often provides clues to renal disease . Normally , only traces of protein are found in urine , and when higher amounts are found , damage to the glomeruli is the likely basis . Unusually large quantities of urine may point to diseases like diabetes mellitus or hypothalamic tumors that cause diabetes insipidus . <hl> The color of urine is determined mostly by the breakdown products of red blood cell destruction ( Figure 25.2 ) . <hl> The “ heme ” of hemoglobin is converted by the liver into water-soluble forms that can be excreted into the bile and indirectly into the urine . This yellow pigment is urochrome . Urine color may also be affected by certain foods like beets , berries , and fava beans . A kidney stone or a cancer of the urinary system may produce sufficient bleeding to manifest as pink or even bright red urine . Diseases of the liver or obstructions of bile drainage from the liver impart a dark “ tea ” or “ cola ” hue to the urine . Dehydration produces darker , concentrated urine that may also possess the slight odor of ammonia . Most of the ammonia produced from protein breakdown is converted into urea by the liver , so ammonia is rarely detected in fresh urine . The strong ammonia odor you may detect in bathrooms or alleys is due to the breakdown of urea into ammonia by bacteria in the environment . About one in five people detect a distinctive odor in their urine after consuming asparagus ; other foods such as onions , garlic , and fish can impart their own aromas ! These food-caused odors are harmless .", "hl_sentences": "The color of urine is determined mostly by the breakdown products of red blood cell destruction ( Figure 25.2 ) .", "question": { "cloze_format": "The color of urine is determined mainly by ________.", "normal_format": "What is the color of urine mainly determined by?", "question_choices": [ "diet", "filtration rate", "byproducts of red blood cell breakdown", "filtration efficiency" ], "question_id": "fs-id2871180", "question_text": "The color of urine is determined mainly by ________." }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 2, "ans_text": "ureters" }, "bloom": "1", "hl_context": "The kidneys and ureters are completely retroperitoneal , and the bladder has a peritoneal covering only over the dome . As urine is formed , it drains into the calyces of the kidney , which merge to form the funnel-shaped renal pelvis in the hilum of each kidney . The renal pelvis narrows to become the ureter of each kidney . As urine passes through the ureter , it does not passively drain into the bladder but rather is propelled by waves of peristalsis . As the ureters enter the pelvis , they sweep laterally , hugging the pelvic walls . As they approach the bladder , they turn medially and pierce the bladder wall obliquely . This is important because it creates an one-way valve ( a physiological sphincter rather than an anatomical sphincter ) that allows urine into the bladder but prevents reflux of urine from the bladder back into the ureter . Children born lacking this oblique course of the ureter through the bladder wall are susceptible to “ vesicoureteral reflux , ” which dramatically increases their risk of serious UTI . Pregnancy also increases the likelihood of reflux and UTI . The ureters are approximately 30 cm long . The inner mucosa is lined with transitional epithelium ( Figure 25.6 ) and scattered goblet cells that secrete protective mucus . <hl> The muscular layer of the ureter consists of longitudinal and circular smooth muscles that create the peristaltic contractions to move the urine into the bladder without the aid of gravity . <hl> Finally , a loose adventitial layer composed of collagen and fat anchors the ureters between the parietal peritoneum and the posterior abdominal wall . 25.3 Gross Anatomy of the Kidney Learning Objectives By the end of this section , you will be able to :", "hl_sentences": "The muscular layer of the ureter consists of longitudinal and circular smooth muscles that create the peristaltic contractions to move the urine into the bladder without the aid of gravity .", "question": { "cloze_format": "Peristaltic contractions occur in the ________.", "normal_format": "Where do Peristaltic contractions occur?", "question_choices": [ "urethra", "bladder", "ureters", "urethra, bladder, and ureters" ], "question_id": "fs-id2773194", "question_text": "Peristaltic contractions occur in the ________." }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 1, "ans_text": "inhibited" }, "bloom": null, "hl_context": "Normal micturition is a result of stretch receptors in the bladder wall that transmit nerve impulses to the sacral region of the spinal cord to generate a spinal reflex . The resulting parasympathetic neural outflow causes contraction of the detrusor muscle and relaxation of the involuntary internal urethral sphincter . <hl> At the same time , the spinal cord inhibits somatic motor neurons , resulting in the relaxation of the skeletal muscle of the external urethral sphincter . <hl> The micturition reflex is active in infants but with maturity , children learn to override the reflex by asserting external sphincter control , thereby delaying voiding ( potty training ) . This reflex may be preserved even in the face of spinal cord injury that results in paraplegia or quadriplegia . However , relaxation of the external sphincter may not be possible in all cases , and therefore , periodic catheterization may be necessary for bladder emptying .", "hl_sentences": "At the same time , the spinal cord inhibits somatic motor neurons , resulting in the relaxation of the skeletal muscle of the external urethral sphincter .", "question": { "cloze_format": "Somatic motor neurons must be ________ to relax the external urethral sphincter to allow urination.", "normal_format": "What must Somatic motor neurons be to relax the external urethral sphincter to allow urination? ", "question_choices": [ "stimulated", "inhibited" ], "question_id": "fs-id2606009", "question_text": "Somatic motor neurons must be ________ to relax the external urethral sphincter to allow urination." }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 2, "ans_text": "bladder" }, "bloom": "1", "hl_context": "<hl> The kidneys and ureters are completely retroperitoneal , and the bladder has a peritoneal covering only over the dome . <hl> As urine is formed , it drains into the calyces of the kidney , which merge to form the funnel-shaped renal pelvis in the hilum of each kidney . The renal pelvis narrows to become the ureter of each kidney . As urine passes through the ureter , it does not passively drain into the bladder but rather is propelled by waves of peristalsis . As the ureters enter the pelvis , they sweep laterally , hugging the pelvic walls . As they approach the bladder , they turn medially and pierce the bladder wall obliquely . This is important because it creates an one-way valve ( a physiological sphincter rather than an anatomical sphincter ) that allows urine into the bladder but prevents reflux of urine from the bladder back into the ureter . Children born lacking this oblique course of the ureter through the bladder wall are susceptible to “ vesicoureteral reflux , ” which dramatically increases their risk of serious UTI . Pregnancy also increases the likelihood of reflux and UTI . The ureters are approximately 30 cm long . The inner mucosa is lined with transitional epithelium ( Figure 25.6 ) and scattered goblet cells that secrete protective mucus . The muscular layer of the ureter consists of longitudinal and circular smooth muscles that create the peristaltic contractions to move the urine into the bladder without the aid of gravity . Finally , a loose adventitial layer composed of collagen and fat anchors the ureters between the parietal peritoneum and the posterior abdominal wall . 25.3 Gross Anatomy of the Kidney Learning Objectives By the end of this section , you will be able to :", "hl_sentences": "The kidneys and ureters are completely retroperitoneal , and the bladder has a peritoneal covering only over the dome .", "question": { "cloze_format": "(The) ___ is/are a part of the urinary system that is not completely retroperitoneal.", "normal_format": "Which part of the urinary system is not completely retroperitoneal?", "question_choices": [ "kidneys", "ureters", "bladder", "nephrons" ], "question_id": "fs-id2587679", "question_text": "Which part of the urinary system is not completely retroperitoneal?" }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 3, "ans_text": "renal columns" }, "bloom": "1", "hl_context": "A frontal section through the kidney reveals an outer region called the renal cortex and an inner region called the medulla ( Figure 25.8 ) . <hl> The renal columns are connective tissue extensions that radiate downward from the cortex through the medulla to separate the most characteristic features of the medulla , the renal pyramids and renal papillae . <hl> The papillae are bundles of collecting ducts that transport urine made by nephrons to the calyces of the kidney for excretion . The renal columns also serve to divide the kidney into 6 – 8 lobes and provide a supportive framework for vessels that enter and exit the cortex . The pyramids and renal columns taken together constitute the kidney lobes .", "hl_sentences": "The renal columns are connective tissue extensions that radiate downward from the cortex through the medulla to separate the most characteristic features of the medulla , the renal pyramids and renal papillae .", "question": { "cloze_format": "The renal pyramids are separated from each other by extensions of the renal cortex called ________.", "normal_format": "The renal pyramids are separated from each other by which extensions of the renal cortex?", "question_choices": [ "renal medulla", "minor calyces", "medullary cortices", "renal columns" ], "question_id": "fs-id1688445", "question_text": "The renal pyramids are separated from each other by extensions of the renal cortex called ________." }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 0, "ans_text": "loop of Henle" }, "bloom": null, "hl_context": "The loop of Henle consists of two sections : thick and thin descending and thin and thick ascending sections . The loops of cortical nephrons do not extend into the renal medulla very far , if at all . <hl> Juxtamedullary nephrons have loops that extend variable distances , some very deep into the medulla . <hl> The descending and ascending portions of the loop are highly specialized to enable recovery of much of the Na + and water that were filtered by the glomerulus . As the forming urine moves through the loop , the osmolarity will change from isosmotic with blood ( about 278 – 300 mOsmol / kg ) to both a very hypertonic solution of about 1200 mOsmol / kg and a very hypotonic solution of about 100 mOsmol / kg . These changes are accomplished by osmosis in the descending limb and active transport in the ascending limb . Solutes and water recovered from these loops are returned to the circulation by way of the vasa recta . In a dissected kidney , it is easy to identify the cortex ; it appears lighter in color compared to the rest of the kidney . All of the renal corpuscles as well as both the proximal convoluted tubules ( PCTs ) and distal convoluted tubules are found here . Some nephrons have a short loop of Henle that does not dip beyond the cortex . These nephrons are called cortical nephrons . <hl> About 15 percent of nephrons have long loops of Henle that extend deep into the medulla and are called juxtamedullary nephrons . <hl> 25.4 Microscopic Anatomy of the Kidney Learning Objectives By the end of this section , you will be able to :", "hl_sentences": "Juxtamedullary nephrons have loops that extend variable distances , some very deep into the medulla . About 15 percent of nephrons have long loops of Henle that extend deep into the medulla and are called juxtamedullary nephrons .", "question": { "cloze_format": "The primary structure found within the medulla is the ________.", "normal_format": "What is the primary structure found within the medulla?", "question_choices": [ "loop of Henle", "minor calyces", "portal system", "ureter" ], "question_id": "fs-id2321507", "question_text": "The primary structure found within the medulla is the ________." }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 0, "ans_text": "it is displaced by the liver" }, "bloom": "1", "hl_context": "<hl> The left kidney is located at about the T12 to L3 vertebrae , whereas the right is lower due to slight displacement by the liver . <hl> Upper portions of the kidneys are somewhat protected by the eleventh and twelfth ribs ( Figure 25.7 ) . Each kidney weighs about 125 – 175 g in males and 115 – 155 g in females . They are about 11 – 14 cm in length , 6 cm wide , and 4 cm thick , and are directly covered by a fibrous capsule composed of dense , irregular connective tissue that helps to hold their shape and protect them . This capsule is covered by a shock-absorbing layer of adipose tissue called the renal fat pad , which in turn is encompassed by a tough renal fascia . The fascia and , to a lesser extent , the overlying peritoneum serve to firmly anchor the kidneys to the posterior abdominal wall in a retroperitoneal position .", "hl_sentences": "The left kidney is located at about the T12 to L3 vertebrae , whereas the right is lower due to slight displacement by the liver .", "question": { "cloze_format": "The right kidney is slightly lower because ________.", "normal_format": "Why is the right kidney slightly lower?", "question_choices": [ "it is displaced by the liver", "it is displace by the heart", "it is slightly smaller", "it needs protection of the lower ribs" ], "question_id": "fs-id2415782", "question_text": "The right kidney is slightly lower because ________." }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 1, "ans_text": "Bowman’s capsule" }, "bloom": "1", "hl_context": "Renal Corpuscle As discussed earlier , the renal corpuscle consists of a tuft of capillaries called the glomerulus that is largely surrounded by Bowman ’ s ( glomerular ) capsule . The glomerulus is a high-pressure capillary bed between afferent and efferent arterioles . <hl> Bowman ’ s capsule surrounds the glomerulus to form a lumen , and captures and directs this filtrate to the PCT . <hl> The outermost part of Bowman ’ s capsule , the parietal layer , is a simple squamous epithelium . It transitions onto the glomerular capillaries in an intimate embrace to form the visceral layer of the capsule . Here , the cells are not squamous , but uniquely shaped cells ( podocytes ) extending finger-like arms ( pedicels ) to cover the glomerular capillaries ( Figure 25.11 ) . These projections interdigitate to form filtration slits , leaving small gaps between the digits to form a sieve . As blood passes through the glomerulus , 10 to 20 percent of the plasma filters between these sieve-like fingers to be captured by Bowman ’ s capsule and funneled to the PCT . Where the fenestrae ( windows ) in the glomerular capillaries match the spaces between the podocyte “ fingers , ” the only thing separating the capillary lumen and the lumen of Bowman ’ s capsule is their shared basement membrane ( Figure 25.12 ) . These three features comprise what is known as the filtration membrane . This membrane permits very rapid movement of filtrate from capillary to capsule though pores that are only 70 nm in diameter .", "hl_sentences": "Bowman ’ s capsule surrounds the glomerulus to form a lumen , and captures and directs this filtrate to the PCT .", "question": { "cloze_format": "Blood filtrate is captured in the lumen of the ________.", "normal_format": "Blood filtrate is captured in the lumen of the what?", "question_choices": [ "glomerulus", "Bowman’s capsule", "calyces", "renal papillae" ], "question_id": "fs-id2057188", "question_text": "Blood filtrate is captured in the lumen of the ________." }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 2, "ans_text": "peritubular and vasa recta" }, "bloom": null, "hl_context": "Nephrons are the “ functional units ” of the kidney ; they cleanse the blood and balance the constituents of the circulation . The afferent arterioles form a tuft of high-pressure capillaries about 200 µm in diameter , the glomerulus . The rest of the nephron consists of a continuous sophisticated tubule whose proximal end surrounds the glomerulus in an intimate embrace — this is Bowman ’ s capsule . The glomerulus and Bowman ’ s capsule together form the renal corpuscle . As mentioned earlier , these glomerular capillaries filter the blood based on particle size . <hl> After passing through the renal corpuscle , the capillaries form a second arteriole , the efferent arteriole ( Figure 25.10 ) . <hl> <hl> These will next form a capillary network around the more distal portions of the nephron tubule , the peritubular capillaries and vasa recta , before returning to the venous system . <hl> As the glomerular filtrate progresses through the nephron , these capillary networks recover most of the solutes and water , and return them to the circulation . Since a capillary bed ( the glomerulus ) drains into a vessel that in turn forms a second capillary bed , the definition of a portal system is met . This is the only portal system in which an arteriole is found between the first and second capillary beds . ( Portal systems also link the hypothalamus to the anterior pituitary , and the blood vessels of the digestive viscera to the liver . )", "hl_sentences": "After passing through the renal corpuscle , the capillaries form a second arteriole , the efferent arteriole ( Figure 25.10 ) . These will next form a capillary network around the more distal portions of the nephron tubule , the peritubular capillaries and vasa recta , before returning to the venous system .", "question": { "cloze_format": "___ are the names of the capillaries following the efferent arteriole.", "normal_format": "What are the names of the capillaries following the efferent arteriole?", "question_choices": [ "arcuate and medullary", "interlobar and interlobular", "peritubular and vasa recta", "peritubular and medullary" ], "question_id": "fs-id2582561", "question_text": "What are the names of the capillaries following the efferent arteriole?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 2, "ans_text": "the nephron" }, "bloom": "1", "hl_context": "<hl> Nephrons are the “ functional units ” of the kidney ; they cleanse the blood and balance the constituents of the circulation . <hl> The afferent arterioles form a tuft of high-pressure capillaries about 200 µm in diameter , the glomerulus . The rest of the nephron consists of a continuous sophisticated tubule whose proximal end surrounds the glomerulus in an intimate embrace — this is Bowman ’ s capsule . The glomerulus and Bowman ’ s capsule together form the renal corpuscle . As mentioned earlier , these glomerular capillaries filter the blood based on particle size . After passing through the renal corpuscle , the capillaries form a second arteriole , the efferent arteriole ( Figure 25.10 ) . These will next form a capillary network around the more distal portions of the nephron tubule , the peritubular capillaries and vasa recta , before returning to the venous system . As the glomerular filtrate progresses through the nephron , these capillary networks recover most of the solutes and water , and return them to the circulation . Since a capillary bed ( the glomerulus ) drains into a vessel that in turn forms a second capillary bed , the definition of a portal system is met . This is the only portal system in which an arteriole is found between the first and second capillary beds . ( Portal systems also link the hypothalamus to the anterior pituitary , and the blood vessels of the digestive viscera to the liver . )", "hl_sentences": "Nephrons are the “ functional units ” of the kidney ; they cleanse the blood and balance the constituents of the circulation .", "question": { "cloze_format": "The functional unit of the kidney is called ________.", "normal_format": "What is the functional unit of the kidney called?", "question_choices": [ "the renal hilus", "the renal corpuscle", "the nephron", "Bowman’s capsule" ], "question_id": "fs-id1483005", "question_text": "The functional unit of the kidney is called ________." }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 1, "ans_text": "Hydrostatic" }, "bloom": null, "hl_context": "To understand why this is so , look more closely at the microenvironment on either side of the filtration membrane . You will find osmotic pressure exerted by the solutes inside the lumen of the capillary as well as inside of Bowman ’ s capsule . Since the filtration membrane limits the size of particles crossing the membrane , the osmotic pressure inside the glomerular capillary is higher than the osmotic pressure in Bowman ’ s capsule . Recall that cells and the medium-to-large proteins cannot pass between the podocyte processes or through the fenestrations of the capillary endothelial cells . This means that red and white blood cells , platelets , albumins , and other proteins too large to pass through the filter remain in the capillary , creating an average colloid osmotic pressure of 30 mm Hg within the capillary . The absence of proteins in Bowman ’ s space ( the lumen within Bowman ’ s capsule ) results in an osmotic pressure near zero . <hl> Thus , the only pressure moving fluid across the capillary wall into the lumen of Bowman ’ s space is hydrostatic pressure . <hl> Hydrostatic ( fluid ) pressure is sufficient to push water through the membrane despite the osmotic pressure working against it . The sum of all of the influences , both osmotic and hydrostatic , results in a net filtration pressure ( NFP ) of about 10 mm Hg ( Figure 25.16 ) .", "hl_sentences": "Thus , the only pressure moving fluid across the capillary wall into the lumen of Bowman ’ s space is hydrostatic pressure .", "question": { "cloze_format": "________ pressure must be greater on the capillary side of the filtration membrane to achieve filtration.", "normal_format": "What pressure must be greater on the capillary side of the filtration membrane to achieve filtration?", "question_choices": [ "Osmotic", "Hydrostatic" ], "question_id": "fs-id2052012", "question_text": "________ pressure must be greater on the capillary side of the filtration membrane to achieve filtration." }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 3, "ans_text": "filtration, absorption, and secretion" }, "bloom": "1", "hl_context": "Nephrons take a simple filtrate of the blood and modify it into urine . Many changes take place in the different parts of the nephron before urine is created for disposal . The term forming urine will be used hereafter to describe the filtrate as it is modified into true urine . <hl> The principle task of the nephron population is to balance the plasma to homeostatic set points and excrete potential toxins in the urine . <hl> <hl> They do this by accomplishing three principle functions — filtration , reabsorption , and secretion . <hl> They also have additional secondary functions that exert control in three areas : blood pressure ( via production of renin ) , red blood cell production ( via the hormone EPO ) , and calcium absorption ( via conversion of calcidiol into calcitriol , the active form of vitamin D ) .", "hl_sentences": "The principle task of the nephron population is to balance the plasma to homeostatic set points and excrete potential toxins in the urine . They do this by accomplishing three principle functions — filtration , reabsorption , and secretion .", "question": { "cloze_format": "Production of urine to modify plasma makeup is the result of ________.", "normal_format": "Production of urine to modify plasma makeup is the result of what?", "question_choices": [ "filtration", "absorption", "secretion", "filtration, absorption, and secretion" ], "question_id": "fs-id1908137", "question_text": "Production of urine to modify plasma makeup is the result of ________." }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 1, "ans_text": "false" }, "bloom": null, "hl_context": "As you can see , there is a low net pressure across the filtration membrane . Intuitively , you should realize that minor changes in osmolarity of the blood or changes in capillary blood pressure result in major changes in the amount of filtrate formed at any given point in time . The kidney is able to cope with a wide range of blood pressures . In large part , this is due to the autoregulatory nature of smooth muscle . When you stretch it , it contracts . Thus , when blood pressure goes up , smooth muscle in the afferent capillaries contracts to limit any increase in blood flow and filtration rate . When blood pressure drops , the same capillaries relax to maintain blood flow and filtration rate . The net result is a relatively steady flow of blood into the glomerulus and a relatively steady filtration rate in spite of significant systemic blood pressure changes . Mean arterial blood pressure is calculated by adding 1/3 of the difference between the systolic and diastolic pressures to the diastolic pressure . Therefore , if the blood pressure is 110/80 , the difference between systolic and diastolic pressure is 30 . One third of this is 10 , and when you add this to the diastolic pressure of 80 , you arrive at a calculated mean arterial pressure of 90 mm Hg . <hl> Therefore , if you use mean arterial pressure for the GBHP in the formula for calculating NFP , you can determine that as long as mean arterial pressure is above approximately 60 mm Hg , the pressure will be adequate to maintain glomerular filtration . <hl> Blood pressures below this level will impair renal function and cause systemic disorders that are severe enough to threaten survival . This condition is called shock .", "hl_sentences": "Therefore , if you use mean arterial pressure for the GBHP in the formula for calculating NFP , you can determine that as long as mean arterial pressure is above approximately 60 mm Hg , the pressure will be adequate to maintain glomerular filtration .", "question": { "cloze_format": "It is ___ that systemic blood pressure must stay above 60 so that the proper amount of filtration occurs.", "normal_format": "Systemic blood pressure must stay above 60 so that the proper amount of filtration occurs.", "question_choices": [ "true", "false" ], "question_id": "fs-id2459453", "question_text": "Systemic blood pressure must stay above 60 so that the proper amount of filtration occurs." }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 1, "ans_text": "the collecting ducts" }, "bloom": "1", "hl_context": "<hl> Regulation of urine volume and osmolarity are major functions of the collecting ducts . <hl> <hl> By varying the amount of water that is recovered , the collecting ducts play a major role in maintaining the body ’ s normal osmolarity . <hl> If the blood becomes hyperosmotic , the collecting ducts recover more water to dilute the blood ; if the blood becomes hyposmotic , the collecting ducts recover less of the water , leading to concentration of the blood . Another way of saying this is : If plasma osmolarity rises , more water is recovered and urine volume decreases ; if plasma osmolarity decreases , less water is recovered and urine volume increases . This function is regulated by the posterior pituitary hormone ADH ( vasopressin ) . With mild dehydration , plasma osmolarity rises slightly . This increase is detected by osmoreceptors in the hypothalamus , which stimulates the release of ADH from the posterior pituitary . If plasma osmolarity decreases slightly , the opposite occurs . With up to 180 liters per day passing through the nephrons of the kidney , it is quite obvious that most of that fluid and its contents must be reabsorbed . That recovery occurs in the PCT , loop of Henle , DCT , and the collecting ducts ( Table 25.5 and Figure 25.17 ) . Various portions of the nephron differ in their capacity to reabsorb water and specific solutes . While much of the reabsorption and secretion occur passively based on concentration gradients , the amount of water that is reabsorbed or lost is tightly regulated . This control is exerted directly by ADH and aldosterone , and indirectly by renin . Most water is recovered in the PCT , loop of Henle , and DCT . About 10 percent ( about 18 L ) reaches the collecting ducts . <hl> The collecting ducts , under the influence of ADH , can recover almost all of the water passing through them , in cases of dehydration , or almost none of the water , in cases of over-hydration . <hl>", "hl_sentences": "Regulation of urine volume and osmolarity are major functions of the collecting ducts . By varying the amount of water that is recovered , the collecting ducts play a major role in maintaining the body ’ s normal osmolarity . The collecting ducts , under the influence of ADH , can recover almost all of the water passing through them , in cases of dehydration , or almost none of the water , in cases of over-hydration .", "question": { "cloze_format": "The fine tuning of water recovery or disposal occurs in ________.", "normal_format": "Where does the fine tuning of water recovery or disposal occur in?", "question_choices": [ "the proximal convoluted tubule", "the collecting ducts", "the ascending loop of Henle", "the distal convoluted tubule" ], "question_id": "fs-id1165447814956", "question_text": "The fine tuning of water recovery or disposal occurs in ________." }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 1, "ans_text": "less frequent action potentials" }, "bloom": null, "hl_context": "The body cannot directly measure blood volume , but blood pressure can be measured . Blood pressure often reflects blood volume and is measured by baroreceptors in the aorta and carotid sinuses . <hl> When blood pressure increases , baroreceptors send more frequent action potentials to the central nervous system , leading to widespread vasodilation . <hl> Included in this vasodilation are the afferent arterioles supplying the glomerulus , resulting in increased GFR , and water loss by the kidneys . If pressure decreases , fewer action potentials travel to the central nervous system , resulting in more sympathetic stimulation-producing vasoconstriction , which will result in decreased filtration and GFR , and water loss .", "hl_sentences": "When blood pressure increases , baroreceptors send more frequent action potentials to the central nervous system , leading to widespread vasodilation .", "question": { "cloze_format": "Vasodilation of blood vessels to the kidneys is due to ________.", "normal_format": "Vasodilation of blood vessels to the kidneys is due to what?", "question_choices": [ "more frequent action potentials", "less frequent action potentials" ], "question_id": "fs-id2528617", "question_text": "Vasodilation of blood vessels to the kidneys is due to ________." }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 0, "ans_text": "contract" }, "bloom": null, "hl_context": "As you can see , there is a low net pressure across the filtration membrane . Intuitively , you should realize that minor changes in osmolarity of the blood or changes in capillary blood pressure result in major changes in the amount of filtrate formed at any given point in time . The kidney is able to cope with a wide range of blood pressures . In large part , this is due to the autoregulatory nature of smooth muscle . When you stretch it , it contracts . <hl> Thus , when blood pressure goes up , smooth muscle in the afferent capillaries contracts to limit any increase in blood flow and filtration rate . <hl> When blood pressure drops , the same capillaries relax to maintain blood flow and filtration rate . The net result is a relatively steady flow of blood into the glomerulus and a relatively steady filtration rate in spite of significant systemic blood pressure changes . Mean arterial blood pressure is calculated by adding 1/3 of the difference between the systolic and diastolic pressures to the diastolic pressure . Therefore , if the blood pressure is 110/80 , the difference between systolic and diastolic pressure is 30 . One third of this is 10 , and when you add this to the diastolic pressure of 80 , you arrive at a calculated mean arterial pressure of 90 mm Hg . Therefore , if you use mean arterial pressure for the GBHP in the formula for calculating NFP , you can determine that as long as mean arterial pressure is above approximately 60 mm Hg , the pressure will be adequate to maintain glomerular filtration . Blood pressures below this level will impair renal function and cause systemic disorders that are severe enough to threaten survival . This condition is called shock .", "hl_sentences": "Thus , when blood pressure goes up , smooth muscle in the afferent capillaries contracts to limit any increase in blood flow and filtration rate .", "question": { "cloze_format": "When blood pressure increases, blood vessels supplying the kidney will ________ to mount a steady rate of filtration.", "normal_format": "When blood pressure increases, how will blood vessels supplying the kidney change to mount a steady filtration rate?", "question_choices": [ "contract", "relax" ], "question_id": "fs-id2340300", "question_text": "When blood pressure increases, blood vessels supplying the kidney will ________ to mount a steady rate of filtration." }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 0, "ans_text": "ATP" }, "bloom": null, "hl_context": "<hl> ATP and adenosine decrease , causing vasodilation <hl>", "hl_sentences": "ATP and adenosine decrease , causing vasodilation", "question": { "cloze_format": "The paracrine chemical ___ causes vasodilation.", "normal_format": "Which of these three paracrine chemicals cause vasodilation?", "question_choices": [ "ATP", "adenosine", "nitric oxide" ], "question_id": "fs-id1848165", "question_text": "Which of these three paracrine chemicals cause vasodilation?" }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 3, "ans_text": "aldosterone" }, "bloom": "1", "hl_context": "Cardiomyocytes of the atria also respond to greater stretch ( as blood pressure rises ) by secreting ANH . <hl> ANH opposes the action of aldosterone by inhibiting the recovery of Na + by the DCT and collecting ducts . <hl> More Na + is lost , and as water follows , total blood volume and pressure decline . In low-pressure states , ANH does not seem to have much effect . <hl> Natriuretic hormones are peptides that stimulate the kidneys to excrete sodium — an effect opposite that of aldosterone . <hl> Natriuretic hormones act by inhibiting aldosterone release and therefore inhibiting Na + recovery in the collecting ducts . If Na + remains in the forming urine , its osmotic force will cause a concurrent loss of water . Natriuretic hormones also inhibit ADH release , which of course will result in less water recovery . Therefore , natriuretic peptides inhibit both Na + and water recovery . One example from this family of hormones is atrial natriuretic hormone ( ANH ) , a 28 - amino acid peptide produced by heart atria in response to over-stretching of the atrial wall . The over-stretching occurs in persons with elevated blood pressure or heart failure . It increases GFR through concurrent vasodilation of the afferent arteriole and vasoconstriction of the efferent arteriole . These events lead to an increased loss of water and sodium in the forming urine . It also decreases sodium reabsorption in the DCT . There is also B-type natriuretic peptide ( BNP ) of 32 amino acids produced in the ventricles of the heart . It has a 10 - fold lower affinity for its receptor , so its effects are less than those of ANH . Its role may be to provide “ fine tuning ” for the regulation of blood pressure . BNP ’ s longer biologic half-life makes it a good diagnostic marker of congestive heart failure ( Figure 25.21 ) .", "hl_sentences": "ANH opposes the action of aldosterone by inhibiting the recovery of Na + by the DCT and collecting ducts . Natriuretic hormones are peptides that stimulate the kidneys to excrete sodium — an effect opposite that of aldosterone .", "question": { "cloze_format": "The hormone that directly opposes the actions of natriuretic hormones is ___.", "normal_format": "What hormone directly opposes the actions of natriuretic hormones?", "question_choices": [ "renin", "nitric oxide", "dopamine", "aldosterone" ], "question_id": "fs-id1530205", "question_text": "What hormone directly opposes the actions of natriuretic hormones?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 3, "ans_text": "angiotensin II" }, "bloom": "1", "hl_context": "<hl> Angiotensin II is a potent vasoconstrictor that plays an immediate role in the regulation of blood pressure . <hl> It acts systemically to cause vasoconstriction as well as constriction of both the afferent and efferent arterioles of the glomerulus . In instances of blood loss or dehydration , it reduces both GFR and renal blood flow , thereby limiting fluid loss and preserving blood volume . Its release is usually stimulated by decreases in blood pressure , and so the preservation of adequate blood pressure is its primary role . As Na + is pumped from the forming urine , water is passively recaptured for the circulation ; this preservation of vascular volume is critically important for the maintenance of a normal blood pressure . Aldosterone is secreted by the adrenal cortex in response to angiotensin II stimulation . <hl> As an extremely potent vasoconstrictor , angiotensin II functions immediately to increase blood pressure . <hl> By also stimulating aldosterone production , it provides a longer-lasting mechanism to support blood pressure by maintaining vascular volume ( water recovery ) .", "hl_sentences": "Angiotensin II is a potent vasoconstrictor that plays an immediate role in the regulation of blood pressure . As an extremely potent vasoconstrictor , angiotensin II functions immediately to increase blood pressure .", "question": { "cloze_format": "___ is a vasoconstrictor.", "normal_format": "Which of these is a vasoconstrictor?", "question_choices": [ "nitric oxide", "natriuretic hormone", "bradykinin", "angiotensin II" ], "question_id": "fs-id1968776", "question_text": "Which of these is a vasoconstrictor?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 0, "ans_text": "increased blood pressure" }, "bloom": "3", "hl_context": "Natriuretic hormones are peptides that stimulate the kidneys to excrete sodium — an effect opposite that of aldosterone . Natriuretic hormones act by inhibiting aldosterone release and therefore inhibiting Na + recovery in the collecting ducts . If Na + remains in the forming urine , its osmotic force will cause a concurrent loss of water . Natriuretic hormones also inhibit ADH release , which of course will result in less water recovery . Therefore , natriuretic peptides inhibit both Na + and water recovery . <hl> One example from this family of hormones is atrial natriuretic hormone ( ANH ) , a 28 - amino acid peptide produced by heart atria in response to over-stretching of the atrial wall . <hl> <hl> The over-stretching occurs in persons with elevated blood pressure or heart failure . <hl> It increases GFR through concurrent vasodilation of the afferent arteriole and vasoconstriction of the efferent arteriole . These events lead to an increased loss of water and sodium in the forming urine . It also decreases sodium reabsorption in the DCT . There is also B-type natriuretic peptide ( BNP ) of 32 amino acids produced in the ventricles of the heart . It has a 10 - fold lower affinity for its receptor , so its effects are less than those of ANH . Its role may be to provide “ fine tuning ” for the regulation of blood pressure . BNP ’ s longer biologic half-life makes it a good diagnostic marker of congestive heart failure ( Figure 25.21 ) .", "hl_sentences": "One example from this family of hormones is atrial natriuretic hormone ( ANH ) , a 28 - amino acid peptide produced by heart atria in response to over-stretching of the atrial wall . The over-stretching occurs in persons with elevated blood pressure or heart failure .", "question": { "cloze_format": "The signal that causes the heart to secrete atrial natriuretic hormone is ___.", "normal_format": "What signal causes the heart to secrete atrial natriuretic hormone?", "question_choices": [ "increased blood pressure", "decreased blood pressure", "increased Na+ levels", "decreased Na+ levels" ], "question_id": "fs-id2484096", "question_text": "What signal causes the heart to secrete atrial natriuretic hormone?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 3, "ans_text": "milk" }, "bloom": "1", "hl_context": "<hl> A diuretic is a compound that increases urine volume . <hl> <hl> Three familiar drinks contain diuretic compounds : coffee , tea , and alcohol . <hl> The caffeine in coffee and tea works by promoting vasodilation in the nephron , which increases GFR . Alcohol increases GFR by inhibiting ADH release from the posterior pituitary , resulting in less water recovery by the collecting duct . In cases of high blood pressure , diuretics may be prescribed to reduce blood volume and , thereby , reduce blood pressure . The most frequently prescribed anti-hypertensive diuretic is hydrochlorothiazide . It inhibits the Na + / Cl – symporter in the DCT and collecting duct . The result is a loss of Na + with water following passively by osmosis . Diuretics are drugs that can increase water loss by interfering with the recapture of solutes and water from the forming urine . They are often prescribed to lower blood pressure . <hl> Coffee , tea , and alcoholic beverages are familiar diuretics . <hl> ADH , a 9 - amino acid peptide released by the posterior pituitary , works to do the exact opposite . It promotes the recovery of water , decreases urine volume , and maintains plasma osmolarity and blood pressure . It does so by stimulating the movement of aquaporin proteins into the apical cell membrane of principal cells of the collecting ducts to form water channels , allowing the transcellular movement of water from the lumen of the collecting duct into the interstitial space in the medulla of the kidney by osmosis . From there , it enters the vasa recta capillaries to return to the circulation . Water is attracted by the high osmotic environment of the deep kidney medulla .", "hl_sentences": "A diuretic is a compound that increases urine volume . Three familiar drinks contain diuretic compounds : coffee , tea , and alcohol . Coffee , tea , and alcoholic beverages are familiar diuretics .", "question": { "cloze_format": "The beverage that does not have a diuretic effect is ___.", "normal_format": "Which of these beverages does not have a diuretic effect?", "question_choices": [ "tea", "coffee", "alcohol", "milk" ], "question_id": "fs-id2576304", "question_text": "Which of these beverages does not have a diuretic effect?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 1, "ans_text": "decreased blood pressure" }, "bloom": "1", "hl_context": "<hl> Decreased blood pressure is also sensed by the granular cells in the afferent arteriole of the JGA . <hl> <hl> In response , the enzyme renin is released . <hl> You saw earlier in the chapter that renin activity leads to an almost immediate rise in blood pressure as activated angiotensin II produces vasoconstriction . The rise in pressure is sustained by the aldosterone effects initiated by angiotensin II ; this includes an increase in Na + retention and water volume . As an aside , late in the menstrual cycle , progesterone has a modest influence on water retention . Due to its structural similarity to aldosterone , progesterone binds to the aldosterone receptor in the collecting duct of the kidney , causing the same , albeit weaker , effect on Na + and water retention .", "hl_sentences": "Decreased blood pressure is also sensed by the granular cells in the afferent arteriole of the JGA . In response , the enzyme renin is released .", "question": { "cloze_format": "Renin is released in response to ________.", "normal_format": "Renin is released in response to which of the following?", "question_choices": [ "increased blood pressure", "decreased blood pressure", "ACE", "diuretics" ], "question_id": "fs-id2302736", "question_text": "Renin is released in response to ________." }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 1, "ans_text": "converts calcidiol into calcitriol" }, "bloom": "1", "hl_context": "Introduction The urinary system has roles you may be well aware of : cleansing the blood and ridding the body of wastes probably come to mind . However , there are additional , equally important functions played by the system . Take for example , regulation of pH , a function shared with the lungs and the buffers in the blood . Additionally , the regulation of blood pressure is a role shared with the heart and blood vessels . What about regulating the concentration of solutes in the blood ? Did you know that the kidney is important in determining the concentration of red blood cells ? Eighty-five percent of the erythropoietin ( EPO ) produced to stimulate red blood cell production is produced in the kidneys . <hl> The kidneys also perform the final synthesis step of vitamin D production , converting calcidiol to calcitriol , the active form of vitamin D . If the kidneys fail , these functions are compromised or lost altogether , with devastating effects on homeostasis . <hl> The affected individual might experience weakness , lethargy , shortness of breath , anemia , widespread edema ( swelling ) , metabolic acidosis , rising potassium levels , heart arrhythmias , and more . Each of these functions is vital to your well-being and survival . The urinary system , controlled by the nervous system , also stores urine until a convenient time for disposal and then provides the anatomical structures to transport this waste liquid to the outside of the body . Failure of nervous control or the anatomical structures leading to a loss of control of urination results in a condition called incontinence . This chapter will help you to understand the anatomy of the urinary system and how it enables the physiologic functions critical to homeostasis . It is best to think of the kidney as a regulator of plasma makeup rather than simply a urine producer . As you read each section , ask yourself this question : “ What happens if this does not work ? ” This question will help you to understand how the urinary system maintains homeostasis and affects all the other systems of the body and the quality of one ’ s life . Interactive Link", "hl_sentences": "The kidneys also perform the final synthesis step of vitamin D production , converting calcidiol to calcitriol , the active form of vitamin D . If the kidneys fail , these functions are compromised or lost altogether , with devastating effects on homeostasis .", "question": { "cloze_format": "The step in vitamin D production that the kidney performs is that it ___.", "normal_format": "Which step in vitamin D production does the kidney perform?", "question_choices": [ "converts cholecalciferol into calcidiol", "converts calcidiol into calcitriol", "stores vitamin D", "none of these" ], "question_id": "fs-id2138805", "question_text": "Which step in vitamin D production does the kidney perform?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 2, "ans_text": "EPO" }, "bloom": "1", "hl_context": "<hl> EPO is a 193 - amino acid protein that stimulates the formation of red blood cells in the bone marrow . <hl> <hl> The kidney produces 85 percent of circulating EPO ; the liver , the remainder . <hl> If you move to a higher altitude , the partial pressure of oxygen is lower , meaning there is less pressure to push oxygen across the alveolar membrane and into the red blood cell . One way the body compensates is to manufacture more red blood cells by increasing EPO production . If you start an aerobic exercise program , your tissues will need more oxygen to cope , and the kidney will respond with more EPO . If erythrocytes are lost due to severe or prolonged bleeding , or under produced due to disease or severe malnutrition , the kidneys come to the rescue by producing more EPO . Renal failure ( loss of EPO production ) is associated with anemia , which makes it difficult for the body to cope with increased oxygen demands or to supply oxygen adequately even under normal conditions . Anemia diminishes performance and can be life threatening . Introduction The urinary system has roles you may be well aware of : cleansing the blood and ridding the body of wastes probably come to mind . However , there are additional , equally important functions played by the system . Take for example , regulation of pH , a function shared with the lungs and the buffers in the blood . Additionally , the regulation of blood pressure is a role shared with the heart and blood vessels . What about regulating the concentration of solutes in the blood ? Did you know that the kidney is important in determining the concentration of red blood cells ? <hl> Eighty-five percent of the erythropoietin ( EPO ) produced to stimulate red blood cell production is produced in the kidneys . <hl> The kidneys also perform the final synthesis step of vitamin D production , converting calcidiol to calcitriol , the active form of vitamin D . If the kidneys fail , these functions are compromised or lost altogether , with devastating effects on homeostasis . The affected individual might experience weakness , lethargy , shortness of breath , anemia , widespread edema ( swelling ) , metabolic acidosis , rising potassium levels , heart arrhythmias , and more . Each of these functions is vital to your well-being and survival . The urinary system , controlled by the nervous system , also stores urine until a convenient time for disposal and then provides the anatomical structures to transport this waste liquid to the outside of the body . Failure of nervous control or the anatomical structures leading to a loss of control of urination results in a condition called incontinence . This chapter will help you to understand the anatomy of the urinary system and how it enables the physiologic functions critical to homeostasis . It is best to think of the kidney as a regulator of plasma makeup rather than simply a urine producer . As you read each section , ask yourself this question : “ What happens if this does not work ? ” This question will help you to understand how the urinary system maintains homeostasis and affects all the other systems of the body and the quality of one ’ s life . Interactive Link", "hl_sentences": "EPO is a 193 - amino acid protein that stimulates the formation of red blood cells in the bone marrow . The kidney produces 85 percent of circulating EPO ; the liver , the remainder . Eighty-five percent of the erythropoietin ( EPO ) produced to stimulate red blood cell production is produced in the kidneys .", "question": { "cloze_format": "The hormone that the kidney produces that stimulates red blood cell production is ___.", "normal_format": "Which hormone does the kidney produce that stimulates red blood cell production?", "question_choices": [ "thrombopoeitin", "vitamin D", "EPO", "renin" ], "question_id": "fs-id2586003", "question_text": "Which hormone does the kidney produce that stimulates red blood cell production?" }, "references_are_paraphrase": null } ]
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25.1 Physical Characteristics of Urine Learning Objectives By the end of this section, you will be able to: Compare and contrast blood plasma, glomerular filtrate, and urine characteristics Describe the characteristics of a normal urine sample, including normal range of pH, osmolarity, and volume The urinary system’s ability to filter the blood resides in about 2 to 3 million tufts of specialized capillaries—the glomeruli—distributed more or less equally between the two kidneys. Because the glomeruli filter the blood based mostly on particle size, large elements like blood cells, platelets, antibodies, and albumen are excluded. The glomerulus is the first part of the nephron, which then continues as a highly specialized tubular structure responsible for creating the final urine composition. All other solutes, such as ions, amino acids, vitamins, and wastes, are filtered to create a filtrate composition very similar to plasma. The glomeruli create about 200 liters (189 quarts) of this filtrate every day, yet you excrete less than two liters of waste you call urine. Characteristics of the urine change, depending on influences such as water intake, exercise, environmental temperature, nutrient intake, and other factors ( Table 25.1 ). Some of the characteristics such as color and odor are rough descriptors of your state of hydration. For example, if you exercise or work outside, and sweat a great deal, your urine will turn darker and produce a slight odor, even if you drink plenty of water. Athletes are often advised to consume water until their urine is clear. This is good advice; however, it takes time for the kidneys to process body fluids and store it in the bladder. Another way of looking at this is that the quality of the urine produced is an average over the time it takes to make that urine. Producing clear urine may take only a few minutes if you are drinking a lot of water or several hours if you are working outside and not drinking much. Normal Urine Characteristics Characteristic Normal values Color Pale yellow to deep amber Odor Odorless Volume 750–2000 mL/24 hour pH 4.5–8.0 Specific gravity 1.003–1.032 Osmolarity 40–1350 mOsmol/kg Urobilinogen 0.2–1.0 mg/100 mL White blood cells 0–2 HPF (per high-power field of microscope) Leukocyte esterase None Protein None or trace Bilirubin <0.3 mg/100 mL Ketones None Nitrites None Blood None Glucose None Table 25.1 Urinalysis (urine analysis) often provides clues to renal disease. Normally, only traces of protein are found in urine, and when higher amounts are found, damage to the glomeruli is the likely basis. Unusually large quantities of urine may point to diseases like diabetes mellitus or hypothalamic tumors that cause diabetes insipidus. The color of urine is determined mostly by the breakdown products of red blood cell destruction ( Figure 25.2 ). The “heme” of hemoglobin is converted by the liver into water-soluble forms that can be excreted into the bile and indirectly into the urine. This yellow pigment is urochrome . Urine color may also be affected by certain foods like beets, berries, and fava beans. A kidney stone or a cancer of the urinary system may produce sufficient bleeding to manifest as pink or even bright red urine. Diseases of the liver or obstructions of bile drainage from the liver impart a dark “tea” or “cola” hue to the urine. Dehydration produces darker, concentrated urine that may also possess the slight odor of ammonia. Most of the ammonia produced from protein breakdown is converted into urea by the liver, so ammonia is rarely detected in fresh urine. The strong ammonia odor you may detect in bathrooms or alleys is due to the breakdown of urea into ammonia by bacteria in the environment. About one in five people detect a distinctive odor in their urine after consuming asparagus; other foods such as onions, garlic, and fish can impart their own aromas! These food-caused odors are harmless. Urine volume varies considerably. The normal range is one to two liters per day ( Table 25.2 ). The kidneys must produce a minimum urine volume of about 500 mL/day to rid the body of wastes. Output below this level may be caused by severe dehydration or renal disease and is termed oliguria . The virtual absence of urine production is termed anuria . Excessive urine production is polyuria , which may be due to diabetes mellitus or diabetes insipidus. In diabetes mellitus, blood glucose levels exceed the number of available sodium-glucose transporters in the kidney, and glucose appears in the urine. The osmotic nature of glucose attracts water, leading to its loss in the urine. In the case of diabetes insipidus, insufficient pituitary antidiuretic hormone (ADH) release or insufficient numbers of ADH receptors in the collecting ducts means that too few water channels are inserted into the cell membranes that line the collecting ducts of the kidney. Insufficient numbers of water channels (aquaporins) reduce water absorption, resulting in high volumes of very dilute urine. Urine Volumes Volume condition Volume Causes Normal 1–2 L/day Polyuria >2.5 L/day Diabetes mellitus; diabetes insipidus; excess caffeine or alcohol; kidney disease; certain drugs, such as diuretics; sickle cell anemia; excessive water intake Oliguria 300–500 mL/day Dehydration; blood loss; diarrhea; cardiogenic shock; kidney disease; enlarged prostate Anuria <50 mL/day Kidney failure; obstruction, such as kidney stone or tumor; enlarged prostate Table 25.2 The pH (hydrogen ion concentration) of the urine can vary more than 1000-fold, from a normal low of 4.5 to a maximum of 8.0. Diet can influence pH; meats lower the pH, whereas citrus fruits, vegetables, and dairy products raise the pH. Chronically high or low pH can lead to disorders, such as the development of kidney stones or osteomalacia. Specific gravity is a measure of the quantity of solutes per unit volume of a solution and is traditionally easier to measure than osmolarity. Urine will always have a specific gravity greater than pure water (water = 1.0) due to the presence of solutes. Laboratories can now measure urine osmolarity directly, which is a more accurate indicator of urinary solutes than specific gravity . Remember that osmolarity is the number of osmoles or milliosmoles per liter of fluid (mOsmol/L). Urine osmolarity ranges from a low of 50–100 mOsmol/L to as high as 1200 mOsmol/L H 2 O. Cells are not normally found in the urine. The presence of leukocytes may indicate a urinary tract infection. Leukocyte esterase is released by leukocytes; if detected in the urine, it can be taken as indirect evidence of a urinary tract infection (UTI). Protein does not normally leave the glomerular capillaries, so only trace amounts of protein should be found in the urine, approximately 10 mg/100 mL in a random sample. If excessive protein is detected in the urine, it usually means that the glomerulus is damaged and is allowing protein to “leak” into the filtrate. Ketones are byproducts of fat metabolism. Finding ketones in the urine suggests that the body is using fat as an energy source in preference to glucose. In diabetes mellitus when there is not enough insulin (type I diabetes mellitus) or because of insulin resistance (type II diabetes mellitus), there is plenty of glucose, but without the action of insulin, the cells cannot take it up, so it remains in the bloodstream. Instead, the cells are forced to use fat as their energy source, and fat consumed at such a level produces excessive ketones as byproducts. These excess ketones will appear in the urine. Ketones may also appear if there is a severe deficiency of proteins or carbohydrates in the diet. Nitrates (NO 3 – ) occur normally in the urine. Gram-negative bacteria metabolize nitrate into nitrite (NO 2 – ), and its presence in the urine is indirect evidence of infection. There should be no blood found in the urine. It may sometimes appear in urine samples as a result of menstrual contamination, but this is not an abnormal condition. Now that you understand what the normal characteristics of urine are, the next section will introduce you to how you store and dispose of this waste product and how you make it. 25.10 The Urinary System and Homeostasis Learning Objectives By the end of this section, you will be able to: Describe the role of the kidneys in vitamin D activation Describe the role of the kidneys in regulating erythropoiesis Provide specific examples to demonstrate how the urinary system responds to maintain homeostasis in the body Explain how the urinary system relates to other body systems in maintaining homeostasis Predict factors or situations affecting the urinary system that could disrupt homeostasis Predict the types of problems that would occur in the body if the urinary system could not maintain homeostasis All systems of the body are interrelated. A change in one system may affect all other systems in the body, with mild to devastating effects. A failure of urinary continence can be embarrassing and inconvenient, but is not life threatening. The loss of other urinary functions may prove fatal. A failure to synthesize vitamin D is one such example. Vitamin D Synthesis In order for vitamin D to become active, it must undergo a hydroxylation reaction in the kidney, that is, an –OH group must be added to calcidiol to make calcitriol (1,25-dihydroxycholecalciferol). Activated vitamin D is important for absorption of Ca ++ in the digestive tract, its reabsorption in the kidney, and the maintenance of normal serum concentrations of Ca ++ and phosphate. Calcium is vitally important in bone health, muscle contraction, hormone secretion, and neurotransmitter release. Inadequate Ca ++ leads to disorders like osteoporosis and osteomalacia in adults and rickets in children. Deficits may also result in problems with cell proliferation, neuromuscular function, blood clotting, and the inflammatory response. Recent research has confirmed that vitamin D receptors are present in most, if not all, cells of the body, reflecting the systemic importance of vitamin D. Many scientists have suggested it be referred to as a hormone rather than a vitamin. Erythropoiesis EPO is a 193-amino acid protein that stimulates the formation of red blood cells in the bone marrow. The kidney produces 85 percent of circulating EPO; the liver, the remainder. If you move to a higher altitude, the partial pressure of oxygen is lower, meaning there is less pressure to push oxygen across the alveolar membrane and into the red blood cell. One way the body compensates is to manufacture more red blood cells by increasing EPO production. If you start an aerobic exercise program, your tissues will need more oxygen to cope, and the kidney will respond with more EPO. If erythrocytes are lost due to severe or prolonged bleeding, or under produced due to disease or severe malnutrition, the kidneys come to the rescue by producing more EPO. Renal failure (loss of EPO production) is associated with anemia, which makes it difficult for the body to cope with increased oxygen demands or to supply oxygen adequately even under normal conditions. Anemia diminishes performance and can be life threatening. Blood Pressure Regulation Due to osmosis, water follows where Na + leads. Much of the water the kidneys recover from the forming urine follows the reabsorption of Na + . ADH stimulation of aquaporin channels allows for regulation of water recovery in the collecting ducts. Normally, all of the glucose is recovered, but loss of glucose control (diabetes mellitus) may result in an osmotic dieresis severe enough to produce severe dehydration and death. A loss of renal function means a loss of effective vascular volume control, leading to hypotension (low blood pressure) or hypertension (high blood pressure), which can lead to stroke, heart attack, and aneurysm formation. The kidneys cooperate with the lungs, liver, and adrenal cortex through the renin–angiotensin–aldosterone system (see Figure 25.14 ). The liver synthesizes and secretes the inactive precursor angiotensinogen. When the blood pressure is low, the kidney synthesizes and releases renin. Renin converts angiotensinogen into angiotensin I, and ACE produced in the lung converts angiotensin I into biologically active angiotensin II ( Figure 25.23 ). The immediate and short-term effect of angiotensin II is to raise blood pressure by causing widespread vasoconstriction. angiotensin II also stimulates the adrenal cortex to release the steroid hormone aldosterone, which results in renal reabsorption of Na + and its associated osmotic recovery of water. The reabsorption of Na + helps to raise and maintain blood pressure over a longer term. Regulation of Osmolarity Blood pressure and osmolarity are regulated in a similar fashion. Severe hypo-osmolarity can cause problems like lysis (rupture) of blood cells or widespread edema, which is due to a solute imbalance. Inadequate solute concentration (such as protein) in the plasma results in water moving toward an area of greater solute concentration, in this case, the interstitial space and cell cytoplasm. If the kidney glomeruli are damaged by an autoimmune illness, large quantities of protein may be lost in the urine. The resultant drop in serum osmolarity leads to widespread edema that, if severe, may lead to damaging or fatal brain swelling. Severe hypertonic conditions may arise with severe dehydration from lack of water intake, severe vomiting, or uncontrolled diarrhea. When the kidney is unable to recover sufficient water from the forming urine, the consequences may be severe (lethargy, confusion, muscle cramps, and finally, death) . Recovery of Electrolytes Sodium, calcium, and potassium must be closely regulated. The role of Na + and Ca ++ homeostasis has been discussed at length. Failure of K + regulation can have serious consequences on nerve conduction, skeletal muscle function, and most significantly, on cardiac muscle contraction and rhythm. pH Regulation Recall that enzymes lose their three-dimensional conformation and, therefore, their function if the pH is too acidic or basic. This loss of conformation may be a consequence of the breaking of hydrogen bonds. Move the pH away from the optimum for a specific enzyme and you may severely hamper its function throughout the body, including hormone binding, central nervous system signaling, or myocardial contraction. Proper kidney function is essential for pH homeostasis. Everyday Connection Stem Cells and Repair of Kidney Damage Stem cells are unspecialized cells that can reproduce themselves via cell division, sometimes after years of inactivity. Under certain conditions, they may differentiate into tissue-specific or organ-specific cells with special functions. In some cases, stem cells may continually divide to produce a mature cell and to replace themselves. Stem cell therapy has an enormous potential to improve the quality of life or save the lives of people suffering from debilitating or life-threatening diseases. There have been several studies in animals, but since stem cell therapy is still in its infancy, there have been limited experiments in humans. Acute kidney injury can be caused by a number of factors, including transplants and other surgeries. It affects 7–10 percent of all hospitalized patients, resulting in the deaths of 35–40 percent of inpatients. In limited studies using mesenchymal stem cells, there have been fewer instances of kidney damage after surgery, the length of hospital stays has been reduced, and there have been fewer readmissions after release. How do these stem cells work to protect or repair the kidney? Scientists are unsure at this point, but some evidence has shown that these stem cells release several growth factors in endocrine and paracrine ways. As further studies are conducted to assess the safety and effectiveness of stem cell therapy, we will move closer to a day when kidney injury is rare, and curative treatments are routine. 25.2 Gross Anatomy of Urine Transport Learning Objectives By the end of this section, you will be able to: Identify the ureters, urinary bladder, and urethra, as well as their location, structure, histology, and function Compare and contrast male and female urethras Describe the micturition reflex Describe voluntary and involuntary neural control of micturition Rather than start with urine formation, this section will start with urine excretion. Urine is a fluid of variable composition that requires specialized structures to remove it from the body safely and efficiently. Blood is filtered, and the filtrate is transformed into urine at a relatively constant rate throughout the day. This processed liquid is stored until a convenient time for excretion. All structures involved in the transport and storage of the urine are large enough to be visible to the naked eye. This transport and storage system not only stores the waste, but it protects the tissues from damage due to the wide range of pH and osmolarity of the urine, prevents infection by foreign organisms, and for the male, provides reproductive functions. Urethra The urethra transports urine from the bladder to the outside of the body for disposal. The urethra is the only urologic organ that shows any significant anatomic difference between males and females; all other urine transport structures are identical ( Figure 25.3 ). The urethra in both males and females begins inferior and central to the two ureteral openings forming the three points of a triangular-shaped area at the base of the bladder called the trigone (Greek tri- = “triangle” and the root of the word “trigonometry”). The urethra tracks posterior and inferior to the pubic symphysis (see Figure 25.3 a ). In both males and females, the proximal urethra is lined by transitional epithelium, whereas the terminal portion is a nonkeratinized, stratified squamous epithelium. In the male, pseudostratified columnar epithelium lines the urethra between these two cell types. Voiding is regulated by an involuntary autonomic nervous system-controlled internal urinary sphincter , consisting of smooth muscle and voluntary skeletal muscle that forms the external urinary sphincter below it. Female Urethra The external urethral orifice is embedded in the anterior vaginal wall inferior to the clitoris, superior to the vaginal opening (introitus), and medial to the labia minora. Its short length, about 4 cm, is less of a barrier to fecal bacteria than the longer male urethra and the best explanation for the greater incidence of UTI in women. Voluntary control of the external urethral sphincter is a function of the pudendal nerve. It arises in the sacral region of the spinal cord, traveling via the S2–S4 nerves of the sacral plexus. Male Urethra The male urethra passes through the prostate gland immediately inferior to the bladder before passing below the pubic symphysis (see Figure 25.3 b ). The length of the male urethra varies between men but averages 20 cm in length. It is divided into four regions: the preprostatic urethra, the prostatic urethra, the membranous urethra, and the spongy or penile urethra. The preprostatic urethra is very short and incorporated into the bladder wall. The prostatic urethra passes through the prostate gland. During sexual intercourse, it receives sperm via the ejaculatory ducts and secretions from the seminal vesicles. Paired Cowper’s glands (bulbourethral glands) produce and secrete mucus into the urethra to buffer urethral pH during sexual stimulation. The mucus neutralizes the usually acidic environment and lubricates the urethra, decreasing the resistance to ejaculation. The membranous urethra passes through the deep muscles of the perineum, where it is invested by the overlying urethral sphincters. The spongy urethra exits at the tip (external urethral orifice) of the penis after passing through the corpus spongiosum. Mucous glands are found along much of the length of the urethra and protect the urethra from extremes of urine pH. Innervation is the same in both males and females. Bladder The urinary bladder collects urine from both ureters ( Figure 25.4 ). The bladder lies anterior to the uterus in females, posterior to the pubic bone and anterior to the rectum. During late pregnancy, its capacity is reduced due to compression by the enlarging uterus, resulting in increased frequency of urination. In males, the anatomy is similar, minus the uterus, and with the addition of the prostate inferior to the bladder. The bladder is a retroperitoneal organ whose "dome" distends superiorly when the bladder is filling with urine. Interactive Link View the University of Michigan WebScope to explore the tissue sample in greater detail. The bladder is a highly distensible organ comprised of irregular crisscrossing bands of smooth muscle collectively called the detrusor muscle . The interior surface is made of transitional cellular epithelium that is structurally suited for the large volume fluctuations of the bladder. When empty, it resembles columnar epithelia, but when stretched, it “transitions” (hence the name) to a squamous appearance (see Figure 25.4 ). Volumes in adults can range from nearly zero to 500–600 mL. The detrusor muscle contracts with significant force in the young. The bladder’s strength diminishes with age, but voluntary contractions of abdominal skeletal muscles can increase intra-abdominal pressure to promote more forceful bladder emptying. Such voluntary contraction is also used in forceful defecation and childbirth. Micturition Reflex Micturition is a less-often used, but proper term for urination or voiding. It results from an interplay of involuntary and voluntary actions by the internal and external urethral sphincters. When bladder volume reaches about 150 mL, an urge to void is sensed but is easily overridden. Voluntary control of urination relies on consciously preventing relaxation of the external urethral sphincter to maintain urinary continence. As the bladder fills, subsequent urges become harder to ignore. Ultimately, voluntary constraint fails with resulting incontinence , which will occur as bladder volume approaches 300 to 400 mL. Normal micturition is a result of stretch receptors in the bladder wall that transmit nerve impulses to the sacral region of the spinal cord to generate a spinal reflex. The resulting parasympathetic neural outflow causes contraction of the detrusor muscle and relaxation of the involuntary internal urethral sphincter. At the same time, the spinal cord inhibits somatic motor neurons, resulting in the relaxation of the skeletal muscle of the external urethral sphincter. The micturition reflex is active in infants but with maturity, children learn to override the reflex by asserting external sphincter control, thereby delaying voiding (potty training). This reflex may be preserved even in the face of spinal cord injury that results in paraplegia or quadriplegia. However, relaxation of the external sphincter may not be possible in all cases, and therefore, periodic catheterization may be necessary for bladder emptying. Nerves involved in the control of urination include the hypogastric, pelvic, and pudendal ( Figure 25.5 ). Voluntary micturition requires an intact spinal cord and functional pudendal nerve arising from the sacral micturition center . Since the external urinary sphincter is voluntary skeletal muscle, actions by cholinergic neurons maintain contraction (and thereby continence) during filling of the bladder. At the same time, sympathetic nervous activity via the hypogastric nerves suppresses contraction of the detrusor muscle. With further bladder stretch, afferent signals traveling over sacral pelvic nerves activate parasympathetic neurons. This activates efferent neurons to release acetylcholine at the neuromuscular junctions, producing detrusor contraction and bladder emptying. Ureters The kidneys and ureters are completely retroperitoneal, and the bladder has a peritoneal covering only over the dome. As urine is formed, it drains into the calyces of the kidney, which merge to form the funnel-shaped renal pelvis in the hilum of each kidney. The renal pelvis narrows to become the ureter of each kidney. As urine passes through the ureter, it does not passively drain into the bladder but rather is propelled by waves of peristalsis. As the ureters enter the pelvis, they sweep laterally, hugging the pelvic walls. As they approach the bladder, they turn medially and pierce the bladder wall obliquely. This is important because it creates an one-way valve (a physiological sphincter rather than an anatomical sphincter ) that allows urine into the bladder but prevents reflux of urine from the bladder back into the ureter. Children born lacking this oblique course of the ureter through the bladder wall are susceptible to “vesicoureteral reflux,” which dramatically increases their risk of serious UTI. Pregnancy also increases the likelihood of reflux and UTI. The ureters are approximately 30 cm long. The inner mucosa is lined with transitional epithelium ( Figure 25.6 ) and scattered goblet cells that secrete protective mucus. The muscular layer of the ureter consists of longitudinal and circular smooth muscles that create the peristaltic contractions to move the urine into the bladder without the aid of gravity. Finally, a loose adventitial layer composed of collagen and fat anchors the ureters between the parietal peritoneum and the posterior abdominal wall. 25.3 Gross Anatomy of the Kidney Learning Objectives By the end of this section, you will be able to: Describe the external structure of the kidney, including its location, support structures, and covering Identify the major internal divisions and structures of the kidney Identify the major blood vessels associated with the kidney and trace the path of blood through the kidney Compare and contrast the cortical and juxtamedullary nephrons Name structures found in the cortex and medulla Describe the physiological characteristics of the cortex and medulla The kidneys lie on either side of the spine in the retroperitoneal space between the parietal peritoneum and the posterior abdominal wall, well protected by muscle, fat, and ribs. They are roughly the size of your fist, and the male kidney is typically a bit larger than the female kidney. The kidneys are well vascularized, receiving about 25 percent of the cardiac output at rest. Interactive Link There have never been sufficient kidney donations to provide a kidney to each person needing one. Watch this video to learn about the TED (Technology, Entertainment, Design) Conference held in March 2011. In this video, Dr. Anthony Atala discusses a cutting-edge technique in which a new kidney is “printed.” The successful utilization of this technology is still several years in the future, but imagine a time when you can print a replacement organ or tissue on demand. External Anatomy The left kidney is located at about the T12 to L3 vertebrae, whereas the right is lower due to slight displacement by the liver. Upper portions of the kidneys are somewhat protected by the eleventh and twelfth ribs ( Figure 25.7 ). Each kidney weighs about 125–175 g in males and 115–155 g in females. They are about 11–14 cm in length, 6 cm wide, and 4 cm thick, and are directly covered by a fibrous capsule composed of dense, irregular connective tissue that helps to hold their shape and protect them. This capsule is covered by a shock-absorbing layer of adipose tissue called the renal fat pad , which in turn is encompassed by a tough renal fascia. The fascia and, to a lesser extent, the overlying peritoneum serve to firmly anchor the kidneys to the posterior abdominal wall in a retroperitoneal position. On the superior aspect of each kidney is the adrenal gland. The adrenal cortex directly influences renal function through the production of the hormone aldosterone to stimulate sodium reabsorption. Internal Anatomy A frontal section through the kidney reveals an outer region called the renal cortex and an inner region called the medulla ( Figure 25.8 ). The renal columns are connective tissue extensions that radiate downward from the cortex through the medulla to separate the most characteristic features of the medulla, the renal pyramids and renal papillae . The papillae are bundles of collecting ducts that transport urine made by nephrons to the calyces of the kidney for excretion. The renal columns also serve to divide the kidney into 6–8 lobes and provide a supportive framework for vessels that enter and exit the cortex. The pyramids and renal columns taken together constitute the kidney lobes. Renal Hilum The renal hilum is the entry and exit site for structures servicing the kidneys: vessels, nerves, lymphatics, and ureters. The medial-facing hila are tucked into the sweeping convex outline of the cortex. Emerging from the hilum is the renal pelvis, which is formed from the major and minor calyxes in the kidney. The smooth muscle in the renal pelvis funnels urine via peristalsis into the ureter. The renal arteries form directly from the descending aorta, whereas the renal veins return cleansed blood directly to the inferior vena cava. The artery, vein, and renal pelvis are arranged in an anterior-to-posterior order. Nephrons and Vessels The renal artery first divides into segmental arteries, followed by further branching to form interlobar arteries that pass through the renal columns to reach the cortex ( Figure 25.9 ). The interlobar arteries, in turn, branch into arcuate arteries, cortical radiate arteries, and then into afferent arterioles. The afferent arterioles service about 1.3 million nephrons in each kidney. Nephrons are the “functional units” of the kidney; they cleanse the blood and balance the constituents of the circulation. The afferent arterioles form a tuft of high-pressure capillaries about 200 µm in diameter, the glomerulus . The rest of the nephron consists of a continuous sophisticated tubule whose proximal end surrounds the glomerulus in an intimate embrace—this is Bowman’s capsule . The glomerulus and Bowman’s capsule together form the renal corpuscle . As mentioned earlier, these glomerular capillaries filter the blood based on particle size. After passing through the renal corpuscle, the capillaries form a second arteriole, the efferent arteriole ( Figure 25.10 ). These will next form a capillary network around the more distal portions of the nephron tubule, the peritubular capillaries and vasa recta , before returning to the venous system. As the glomerular filtrate progresses through the nephron, these capillary networks recover most of the solutes and water, and return them to the circulation. Since a capillary bed (the glomerulus) drains into a vessel that in turn forms a second capillary bed, the definition of a portal system is met. This is the only portal system in which an arteriole is found between the first and second capillary beds. (Portal systems also link the hypothalamus to the anterior pituitary, and the blood vessels of the digestive viscera to the liver.) Interactive Link Visit this link to view an interactive tutorial of the flow of blood through the kidney. Cortex In a dissected kidney, it is easy to identify the cortex; it appears lighter in color compared to the rest of the kidney. All of the renal corpuscles as well as both the proximal convoluted tubules (PCTs) and distal convoluted tubules are found here. Some nephrons have a short loop of Henle that does not dip beyond the cortex. These nephrons are called cortical nephrons . About 15 percent of nephrons have long loops of Henle that extend deep into the medulla and are called juxtamedullary nephrons . 25.4 Microscopic Anatomy of the Kidney Learning Objectives By the end of this section, you will be able to: Distinguish the histological differences between the renal cortex and medulla Describe the structure of the filtration membrane Identify the major structures and subdivisions of the renal corpuscles, renal tubules, and renal capillaries Discuss the function of the peritubular capillaries and vasa recta Identify the location of the juxtaglomerular apparatus and describe the cells that line it Describe the histology of the proximal convoluted tubule, loop of Henle, distal convoluted tubule, and collecting ducts The renal structures that conduct the essential work of the kidney cannot be seen by the naked eye. Only a light or electron microscope can reveal these structures. Even then, serial sections and computer reconstruction are necessary to give us a comprehensive view of the functional anatomy of the nephron and its associated blood vessels. Nephrons: The Functional Unit Nephrons take a simple filtrate of the blood and modify it into urine. Many changes take place in the different parts of the nephron before urine is created for disposal. The term forming urine will be used hereafter to describe the filtrate as it is modified into true urine. The principle task of the nephron population is to balance the plasma to homeostatic set points and excrete potential toxins in the urine. They do this by accomplishing three principle functions—filtration, reabsorption, and secretion. They also have additional secondary functions that exert control in three areas: blood pressure (via production of renin ), red blood cell production (via the hormone EPO), and calcium absorption (via conversion of calcidiol into calcitriol, the active form of vitamin D). Renal Corpuscle As discussed earlier, the renal corpuscle consists of a tuft of capillaries called the glomerulus that is largely surrounded by Bowman’s (glomerular) capsule. The glomerulus is a high-pressure capillary bed between afferent and efferent arterioles. Bowman’s capsule surrounds the glomerulus to form a lumen, and captures and directs this filtrate to the PCT. The outermost part of Bowman’s capsule, the parietal layer, is a simple squamous epithelium. It transitions onto the glomerular capillaries in an intimate embrace to form the visceral layer of the capsule. Here, the cells are not squamous, but uniquely shaped cells ( podocytes ) extending finger-like arms ( pedicels ) to cover the glomerular capillaries ( Figure 25.11 ). These projections interdigitate to form filtration slits , leaving small gaps between the digits to form a sieve. As blood passes through the glomerulus, 10 to 20 percent of the plasma filters between these sieve-like fingers to be captured by Bowman’s capsule and funneled to the PCT. Where the fenestrae (windows) in the glomerular capillaries match the spaces between the podocyte “fingers,” the only thing separating the capillary lumen and the lumen of Bowman’s capsule is their shared basement membrane ( Figure 25.12 ). These three features comprise what is known as the filtration membrane. This membrane permits very rapid movement of filtrate from capillary to capsule though pores that are only 70 nm in diameter. The fenestrations prevent filtration of blood cells or large proteins, but allow most other constituents through. These substances cross readily if they are less than 4 nm in size and most pass freely up to 8 nm in size. An additional factor affecting the ability of substances to cross this barrier is their electric charge. The proteins associated with these pores are negatively charged, so they tend to repel negatively charged substances and allow positively charged substances to pass more readily. The basement membrane prevents filtration of medium-to-large proteins such as globulins. There are also mesangial cells in the filtration membrane that can contract to help regulate the rate of filtration of the glomerulus. Overall, filtration is regulated by fenestrations in capillary endothelial cells, podocytes with filtration slits, membrane charge, and the basement membrane between capillary cells. The result is the creation of a filtrate that does not contain cells or large proteins, and has a slight predominance of positively charged substances. Lying just outside Bowman’s capsule and the glomerulus is the juxtaglomerular apparatus (JGA) ( Figure 25.13 ). At the juncture where the afferent and efferent arterioles enter and leave Bowman’s capsule, the initial part of the distal convoluted tubule (DCT) comes into direct contact with the arterioles. The wall of the DCT at that point forms a part of the JGA known as the macula densa . This cluster of cuboidal epithelial cells monitors the fluid composition of fluid flowing through the DCT. In response to the concentration of Na + in the fluid flowing past them, these cells release paracrine signals. They also have a single, nonmotile cilium that responds to the rate of fluid movement in the tubule. The paracrine signals released in response to changes in flow rate and Na + concentration are adenosine triphosphate (ATP) and adenosine. A second cell type in this apparatus is the juxtaglomerular cell . This is a modified, smooth muscle cell lining the afferent arteriole that can contract or relax in response to ATP or adenosine released by the macula densa. Such contraction and relaxation regulate blood flow to the glomerulus. If the osmolarity of the filtrate is too high (hyperosmotic), the juxtaglomerular cells will contract, decreasing the glomerular filtration rate (GFR) so less plasma is filtered, leading to less urine formation and greater retention of fluid. This will ultimately decrease blood osmolarity toward the physiologic norm. If the osmolarity of the filtrate is too low, the juxtaglomerular cells will relax, increasing the GFR and enhancing the loss of water to the urine, causing blood osmolarity to rise. In other words, when osmolarity goes up, filtration and urine formation decrease and water is retained. When osmolarity goes down, filtration and urine formation increase and water is lost by way of the urine. The net result of these opposing actions is to keep the rate of filtration relatively constant. A second function of the macula densa cells is to regulate renin release from the juxtaglomerular cells of the afferent arteriole ( Figure 25.14 ). Active renin is a protein comprised of 304 amino acids that cleaves several amino acids from angiotensinogen to produce angiotensin I . Angiotensin I is not biologically active until converted to angiotensin II by angiotensin-converting enzyme (ACE) from the lungs. Angiotensin II is a systemic vasoconstrictor that helps to regulate blood pressure by increasing it. Angiotensin II also stimulates the release of the steroid hormone aldosterone from the adrenal cortex. Aldosterone stimulates Na + reabsorption by the kidney, which also results in water retention and increased blood pressure. Proximal Convoluted Tubule (PCT) Filtered fluid collected by Bowman’s capsule enters into the PCT. It is called convoluted due to its tortuous path. Simple cuboidal cells form this tubule with prominent microvilli on the luminal surface, forming a brush border . These microvilli create a large surface area to maximize the absorption and secretion of solutes (Na + , Cl – , glucose, etc.), the most essential function of this portion of the nephron. These cells actively transport ions across their membranes, so they possess a high concentration of mitochondria in order to produce sufficient ATP. Loop of Henle The descending and ascending portions of the loop of Henle (sometimes referred to as the nephron loop) are, of course, just continuations of the same tubule. They run adjacent and parallel to each other after having made a hairpin turn at the deepest point of their descent. The descending loop of Henle consists of an initial short, thick portion and long, thin portion, whereas the ascending loop consists of an initial short, thin portion followed by a long, thick portion. The descending thick portion consists of simple cuboidal epithelium similar to that of the PCT. The descending and ascending thin portions consists of simple squamous epithelium. As you will see later, these are important differences, since different portions of the loop have different permeabilities for solutes and water. The ascending thick portion consists of simple cuboidal epithelium similar to the DCT. Distal Convoluted Tubule (DCT) The DCT, like the PCT, is very tortuous and formed by simple cuboidal epithelium, but it is shorter than the PCT. These cells are not as active as those in the PCT; thus, there are fewer microvilli on the apical surface. However, these cells must also pump ions against their concentration gradient, so you will find of large numbers of mitochondria, although fewer than in the PCT. Collecting Ducts The collecting ducts are continuous with the nephron but not technically part of it. In fact, each duct collects filtrate from several nephrons for final modification. Collecting ducts merge as they descend deeper in the medulla to form about 30 terminal ducts, which empty at a papilla. They are lined with simple squamous epithelium with receptors for ADH. When stimulated by ADH, these cells will insert aquaporin channel proteins into their membranes, which as their name suggests, allow water to pass from the duct lumen through the cells and into the interstitial spaces to be recovered by the vasa recta. This process allows for the recovery of large amounts of water from the filtrate back into the blood. In the absence of ADH, these channels are not inserted, resulting in the excretion of water in the form of dilute urine. Most, if not all, cells of the body contain aquaporin molecules, whose channels are so small that only water can pass. At least 10 types of aquaporins are known in humans, and six of those are found in the kidney. The function of all aquaporins is to allow the movement of water across the lipid-rich, hydrophobic cell membrane ( Figure 25.15 ). 25.5 Physiology of Urine Formation Learning Objectives By the end of this section, you will be able to: Describe the hydrostatic and colloid osmotic forces that favor and oppose filtration Describe glomerular filtration rate (GFR), state the average value of GFR, and explain how clearance rate can be used to measure GFR Predict specific factors that will increase or decrease GFR State the percent of the filtrate that is normally reabsorbed and explain why the process of reabsorption is so important Calculate daily urine production List common symptoms of kidney failure Having reviewed the anatomy and microanatomy of the urinary system, now is the time to focus on the physiology. You will discover that different parts of the nephron utilize specific processes to produce urine: filtration, reabsorption, and secretion. You will learn how each of these processes works and where they occur along the nephron and collecting ducts. The physiologic goal is to modify the composition of the plasma and, in doing so, produce the waste product urine. Failure of the renal anatomy and/or physiology can lead suddenly or gradually to renal failure. In this event, a number of symptoms, signs, or laboratory findings point to the diagnosis ( Table 25.3 ). Symptoms of Kidney Failure Weakness Lethargy Shortness of breath Widespread edema Anemia Metabolic acidosis Metabolic alkalosis Heart arrhythmias Uremia (high urea level in the blood) Loss of appetite Fatigue Excessive urination Oliguria (too little urine output) Table 25.3 Glomerular Filtration Rate (GFR) The volume of filtrate formed by both kidneys per minute is termed the glomerular filtration rate (GFR) . The heart pumps about 5 L blood per min under resting conditions. Approximately 20 percent or one liter enters the kidneys to be filtered. On average, this liter results in the production of about 125 mL/min filtrate produced in men (range of 90 to 140 mL/min) and 105 mL/min filtrate produced in women (range of 80 to 125 mL/min). This amount equates to a volume of about 180 L/day in men and 150 L/day in women. Ninety-nine percent of this filtrate is returned to the circulation by reabsorption so that only about 1–2 liters of urine are produced per day ( Table 25.4 ). Calculating Urine Formation per Day Flow per minute (mL) Calculation Renal blood flow 1050 Cardiac output is about 5000 mL/minute, of which 21 percent flows through the kidney. 5000*0.21 = 1050 mL blood/min Renal plasma flow 578 Renal plasma flow equals the blood flow per minute times the hematocrit. If a person has a hematocrit of 45, then the renal plasma flow is 55 percent. 1050*0.55 = 578 mL plasma/min Glomerular filtration rate 110 The GFR is the amount of plasma entering Bowman’s capsule per minute. It is the renal plasma flow times the fraction that enters the renal capsule (19 percent). 578*0.19 = 110 mL filtrate/min Urine 1296 ml/day The filtrate not recovered by the kidney is the urine that will be eliminated. It is the GFR times the fraction of the filtrate that is not reabsorbed (0.8 percent). 110*.008 = 0.9 mL urine /min Multiply urine/min times 60 minutes times 24 hours to get daily urine production. 0.9*60*24 = 1296 mL/day urine Table 25.4 GFR is influenced by the hydrostatic pressure and colloid osmotic pressure on either side of the capillary membrane of the glomerulus. Recall that filtration occurs as pressure forces fluid and solutes through a semipermeable barrier with the solute movement constrained by particle size. Hydrostatic pressure is the pressure produced by a fluid against a surface. If you have a fluid on both sides of a barrier, both fluids exert a pressure in opposing directions. Net fluid movement will be in the direction of the lower pressure. Osmosis is the movement of solvent (water) across a membrane that is impermeable to a solute in the solution. This creates a pressure, osmotic pressure, which will exist until the solute concentration is the same on both sides of a semipermeable membrane. As long as the concentration differs, water will move. Glomerular filtration occurs when glomerular hydrostatic pressure exceeds the luminal hydrostatic pressure of Bowman’s capsule. There is also an opposing force, the osmotic pressure, which is typically higher in the glomerular capillary. To understand why this is so, look more closely at the microenvironment on either side of the filtration membrane. You will find osmotic pressure exerted by the solutes inside the lumen of the capillary as well as inside of Bowman’s capsule. Since the filtration membrane limits the size of particles crossing the membrane, the osmotic pressure inside the glomerular capillary is higher than the osmotic pressure in Bowman’s capsule. Recall that cells and the medium-to-large proteins cannot pass between the podocyte processes or through the fenestrations of the capillary endothelial cells. This means that red and white blood cells, platelets, albumins, and other proteins too large to pass through the filter remain in the capillary, creating an average colloid osmotic pressure of 30 mm Hg within the capillary. The absence of proteins in Bowman’s space (the lumen within Bowman’s capsule) results in an osmotic pressure near zero. Thus, the only pressure moving fluid across the capillary wall into the lumen of Bowman’s space is hydrostatic pressure. Hydrostatic (fluid) pressure is sufficient to push water through the membrane despite the osmotic pressure working against it. The sum of all of the influences, both osmotic and hydrostatic, results in a net filtration pressure (NFP) of about 10 mm Hg ( Figure 25.16 ). A proper concentration of solutes in the blood is important in maintaining osmotic pressure both in the glomerulus and systemically. There are disorders in which too much protein passes through the filtration slits into the kidney filtrate. This excess protein in the filtrate leads to a deficiency of circulating plasma proteins. In turn, the presence of protein in the urine increases its osmolarity; this holds more water in the filtrate and results in an increase in urine volume. Because there is less circulating protein, principally albumin, the osmotic pressure of the blood falls. Less osmotic pressure pulling water into the capillaries tips the balance towards hydrostatic pressure, which tends to push it out of the capillaries. The net effect is that water is lost from the circulation to interstitial tissues and cells. This “plumps up” the tissues and cells, a condition termed systemic edema . Net Filtration Pressure (NFP) NFP determines filtration rates through the kidney. It is determined as follows: NFP = Glomerular blood hydrostatic pressure (GBHP) – [capsular hydrostatic pressure (CHP) + blood colloid osmotic pressure (BCOP)] = 10 mm Hg That is: NFP = GBHP – [CHP + BCOP] = 10 mm Hg Or: NFP = 55 – [15 + 30] = 10 mm Hg As you can see, there is a low net pressure across the filtration membrane. Intuitively, you should realize that minor changes in osmolarity of the blood or changes in capillary blood pressure result in major changes in the amount of filtrate formed at any given point in time. The kidney is able to cope with a wide range of blood pressures. In large part, this is due to the autoregulatory nature of smooth muscle. When you stretch it, it contracts. Thus, when blood pressure goes up, smooth muscle in the afferent capillaries contracts to limit any increase in blood flow and filtration rate. When blood pressure drops, the same capillaries relax to maintain blood flow and filtration rate. The net result is a relatively steady flow of blood into the glomerulus and a relatively steady filtration rate in spite of significant systemic blood pressure changes. Mean arterial blood pressure is calculated by adding 1/3 of the difference between the systolic and diastolic pressures to the diastolic pressure. Therefore, if the blood pressure is 110/80, the difference between systolic and diastolic pressure is 30. One third of this is 10, and when you add this to the diastolic pressure of 80, you arrive at a calculated mean arterial pressure of 90 mm Hg. Therefore, if you use mean arterial pressure for the GBHP in the formula for calculating NFP, you can determine that as long as mean arterial pressure is above approximately 60 mm Hg, the pressure will be adequate to maintain glomerular filtration. Blood pressures below this level will impair renal function and cause systemic disorders that are severe enough to threaten survival. This condition is called shock. Determination of the GFR is one of the tools used to assess the kidney’s excretory function. This is more than just an academic exercise. Since many drugs are excreted in the urine, a decline in renal function can lead to toxic accumulations. Additionally, administration of appropriate drug dosages for those drugs primarily excreted by the kidney requires an accurate assessment of GFR. GFR can be estimated closely by intravenous administration of inulin . Inulin is a plant polysaccharide that is neither reabsorbed nor secreted by the kidney. Its appearance in the urine is directly proportional to the rate at which it is filtered by the renal corpuscle. However, since measuring inulin clearance is cumbersome in the clinical setting, most often, the GFR is estimated by measuring naturally occurring creatinine, a protein-derived molecule produced by muscle metabolism that is not reabsorbed and only slightly secreted by the nephron. 25.6 Tubular Reabsorption Learning Objectives By the end of this section, you will be able to: List specific transport mechanisms occurring in different parts of the nephron, including active transport, osmosis, facilitated diffusion, and passive electrochemical gradients List the different membrane proteins of the nephron, including channels, transporters, and ATPase pumps Compare and contrast passive and active tubular reabsorption Explain why the differential permeability or impermeability of specific sections of the nephron tubules is necessary for urine formation Describe how and where water, organic compounds, and ions are reabsorbed in the nephron Explain the role of the loop of Henle, the vasa recta, and the countercurrent multiplication mechanisms in the concentration of urine List the locations in the nephron where tubular secretion occurs With up to 180 liters per day passing through the nephrons of the kidney, it is quite obvious that most of that fluid and its contents must be reabsorbed. That recovery occurs in the PCT, loop of Henle, DCT, and the collecting ducts ( Table 25.5 and Figure 25.17 ). Various portions of the nephron differ in their capacity to reabsorb water and specific solutes. While much of the reabsorption and secretion occur passively based on concentration gradients, the amount of water that is reabsorbed or lost is tightly regulated. This control is exerted directly by ADH and aldosterone, and indirectly by renin. Most water is recovered in the PCT, loop of Henle, and DCT. About 10 percent (about 18 L) reaches the collecting ducts. The collecting ducts, under the influence of ADH, can recover almost all of the water passing through them, in cases of dehydration, or almost none of the water, in cases of over-hydration. Substances Secreted or Reabsorbed in the Nephron and Their Locations Substance PCT Loop of Henle DCT Collecting ducts Glucose Almost 100 percent reabsorbed; secondary active transport with Na + Oligopeptides, proteins, amino acids Almost 100 percent reabsorbed; symport with Na + Vitamins Reabsorbed Lactate Reabsorbed Creatinine Secreted Urea 50 percent reabsorbed by diffusion; also secreted Secretion, diffusion in descending limb Reabsorption in medullary collecting ducts; diffusion Sodium 65 percent actively reabsorbed 25 percent reabsorbed in thick ascending limb; active transport 5 percent reabsorbed; active 5 percent reabsorbed, stimulated by aldosterone; active Chloride Reabsorbed, symport with Na + , diffusion Reabsorbed in thin and thick ascending limb; diffusion in ascending limb Reabsorbed; diffusion Reabsorbed; symport Water 67 percent reabsorbed osmotically with solutes 15 percent reabsorbed in descending limb; osmosis 8 percent reabsorbed if ADH; osmosis Variable amounts reabsorbed, controlled by ADH, osmosis HCO 3 - 80–90 percent symport reabsorption with Na + Reabsorbed, symport with Na + and antiport with Cl – ; in ascending limb Reabsorbed antiport with Cl – H + Secreted; diffusion Secreted; active Secreted; active NH 4 + Secreted; diffusion Secreted; diffusion Secreted; diffusion Some drugs Secreted Secreted; active Secreted; active Potassium 65 percent reabsorbed; diffusion 20 percent reabsorbed in thick ascending limb; symport Secreted; active Secretion controlled by aldosterone; active Calcium Reabsorbed; diffusion Reabsorbed in thick ascending limb; diffusion Reabsorbed if parathyroid hormone present; active Magnesium Reabsorbed; diffusion Reabsorbed in thick ascending limb; diffusion Reabsorbed Phosphate 85 percent reabsorbed, inhibited by parathyroid hormone, diffusion Reabsorbed; diffusion Table 25.5 Mechanisms of Recovery Mechanisms by which substances move across membranes for reabsorption or secretion include active transport, diffusion, facilitated diffusion, secondary active transport, and osmosis. These were discussed in an earlier chapter, and you may wish to review them. Active transport utilizes energy, usually the energy found in a phosphate bond of ATP, to move a substance across a membrane from a low to a high concentration. It is very specific and must have an appropriately shaped receptor for the substance to be transported. An example would be the active transport of Na + out of a cell and K + into a cell by the Na + /K + pump. Both ions are moved in opposite directions from a lower to a higher concentration. Simple diffusion moves a substance from a higher to a lower concentration down its concentration gradient. It requires no energy and only needs to be soluble. Facilitated diffusion is similar to diffusion in that it moves a substance down its concentration gradient. The difference is that it requires specific membrane receptors or channel proteins for movement. The movement of glucose and, in certain situations, Na + ions, is an example of facilitated diffusion. In some cases of mediated transport, two different substances share the same channel protein port; these mechanisms are described by the terms symport and antiport. Symport mechanisms move two or more substances in the same direction at the same time, whereas antiport mechanisms move two or more substances in opposite directions across the cell membrane. Both mechanisms may utilize concentration gradients maintained by ATP pumps. As described previously, when active transport powers the transport of another substance in this way, it is called “secondary active transport.” Glucose reabsorption in the kidneys is by secondary active transport. Na + /K + ATPases on the basal membrane of a tubular cell constantly pump Na + out of the cell, maintaining a strong electrochemical gradient for Na + to move into the cell from the tubular lumen. On the luminal (apical) surface, a Na + /glucose symport protein assists both Na+ and glucose movement into the cell. The cotransporter moves glucose into the cell against its concentration gradient as Na + moves down the electrochemical gradient created by the basal membranes Na + /K + ATPases. The glucose molecule then diffuses across the basal membrane by facilitated diffusion into the interstitial space and from there into peritubular capillaries. Most of the Ca ++ , Na + , glucose, and amino acids must be reabsorbed by the nephron to maintain homeostatic plasma concentrations. Other substances, such as urea, K + , ammonia (NH 3) , creatinine, and some drugs are secreted into the filtrate as waste products. Acid–base balance is maintained through actions of the lungs and kidneys: The lungs rid the body of H + , whereas the kidneys secrete or reabsorb H + and HCO 3 – ( Table 25.6 ). In the case of urea, about 50 percent is passively reabsorbed by the PCT. More is recovered by in the collecting ducts as needed. ADH induces the insertion of urea transporters and aquaporin channel proteins. Substances Filtered and Reabsorbed by the Kidney per 24 Hours Substance Amount filtered (grams) Amount reabsorbed (grams) Amount in urine (grams) Water 180 L 179 L 1 L Proteins 10–20 10–20 0 Chlorine 630 625 5 Sodium 540 537 3 Bicarbonate 300 299.7 0.3 Glucose 180 180 0 Urea 53 28 25 Potassium 28 24 4 Uric acid 8.5 7.7 0.8 Creatinine 1.4 0 1.4 Table 25.6 Reabsorption and Secretion in the PCT The renal corpuscle filters the blood to create a filtrate that differs from blood mainly in the absence of cells and large proteins. From this point to the ends of the collecting ducts, the filtrate or forming urine is undergoing modification through secretion and reabsorption before true urine is produced. The first point at which the forming urine is modified is in the PCT. Here, some substances are reabsorbed, whereas others are secreted. Note the use of the term “reabsorbed.” All of these substances were “absorbed” in the digestive tract—99 percent of the water and most of the solutes filtered by the nephron must be reabsorbed. Water and substances that are reabsorbed are returned to the circulation by the peritubular and vasa recta capillaries. It is important to understand the difference between the glomerulus and the peritubular and vasa recta capillaries. The glomerulus has a relatively high pressure inside its capillaries and can sustain this by dilating the afferent arteriole while constricting the efferent arteriole. This assures adequate filtration pressure even as the systemic blood pressure varies. Movement of water into the peritubular capillaries and vasa recta will be influenced primarily by osmolarity and concentration gradients. Sodium is actively pumped out of the PCT into the interstitial spaces between cells and diffuses down its concentration gradient into the peritubular capillary. As it does so, water will follow passively to maintain an isotonic fluid environment inside the capillary. This is called obligatory water reabsorption, because water is “obliged” to follow the Na + ( Figure 25.18 ). More substances move across the membranes of the PCT than any other portion of the nephron. Many of these substances (amino acids and glucose) use symport mechanisms for transport along with Na + . Antiport, active transport, diffusion, and facilitated diffusion are additional mechanisms by which substances are moved from one side of a membrane to the other. Recall that cells have two surfaces: apical and basal. The apical surface is the one facing the lumen or open space of a cavity or tube, in this case, the inside of the PCT. The basal surface of the cell faces the connective tissue base to which the cell attaches (basement membrane) or the cell membrane closer to the basement membrane if there is a stratified layer of cells. In the PCT, there is a single layer of simple cuboidal endothelial cells against the basement membrane. The numbers and particular types of pumps and channels vary between the apical and basilar surfaces. A few of the substances that are transported with Na + (symport mechanism) on the apical membrane include Cl – , Ca ++ , amino acids, glucose, and PO 4 3 − PO 4 3 − MathType@MTEF@5@5@+=feaagyart1ev2aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLnhiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq=Jc9vqaqpepm0xbba9pwe9Q8fs0=yqaqpepae9pg0FirpepeKkFr0xfr=xfr=xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaGaaeiuaiaab+eadaqhaaWcbaGaaGinaaqaaiaaiodacqGHsislaaaaaa@3A2D@ . Sodium is actively exchanged for K + using ATP on the basal membrane. Most of the substances transported by a symport mechanism on the apical membrane are transported by facilitated diffusion on the basal membrane. At least three ions, K + , Ca ++ , and Mg ++ , diffuse laterally between adjacent cell membranes (transcellular). About 67 percent of the water, Na + , and K + entering the nephron is reabsorbed in the PCT and returned to the circulation. Almost 100 percent of glucose, amino acids, and other organic substances such as vitamins are normally recovered here. Some glucose may appear in the urine if circulating glucose levels are high enough that all the glucose transporters in the PCT are saturated, so that their capacity to move glucose is exceeded (transport maximum, or T m ). In men, the maximum amount of glucose that can be recovered is about 375 mg/min, whereas in women, it is about 300 mg/min. This recovery rate translates to an arterial concentration of about 200 mg/dL. Though an exceptionally high sugar intake might cause sugar to appear briefly in the urine, the appearance of glycosuria usually points to type I or II diabetes mellitus. The transport of glucose from the lumen of the PCT to the interstitial space is similar to the way it is absorbed by the small intestine. Both glucose and Na + bind simultaneously to the same symport proteins on the apical surface of the cell to be transported in the same direction, toward the interstitial space. Sodium moves down its electrochemical and concentration gradient into the cell and takes glucose with it. Na + is then actively pumped out of the cell at the basal surface of the cell into the interstitial space. Glucose leaves the cell to enter the interstitial space by facilitated diffusion. The energy to move glucose comes from the Na + /K + ATPase that pumps Na + out of the cell on the basal surface. Fifty percent of Cl – and variable quantities of Ca ++ , Mg ++ , and HPO 4 2 − HPO 4 2 − MathType@MTEF@5@5@+=feaagyart1ev2aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLnhiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq=Jc9vqaqpepm0xbba9pwe9Q8fs0=yqaqpepae9pg0FirpepeKkFr0xfr=xfr=xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaGaaeisaiaabcfacaqGpbWaa0baaSqaaiaaisdaaeaacaaIYaGaeyOeI0caaaaa@3AF7@ are also recovered in the PCT. Recovery of bicarbonate (HCO 3 – ) is vital to the maintenance of acid–base balance, since it is a very powerful and fast-acting buffer. An important enzyme is used to catalyze this mechanism: carbonic anhydrase (CA). This same enzyme and reaction is used in red blood cells in the transportation of CO 2 , in the stomach to produce hydrochloric acid, and in the pancreas to produce HCO 3 – to buffer acidic chyme from the stomach. In the kidney, most of the CA is located within the cell, but a small amount is bound to the brush border of the membrane on the apical surface of the cell. In the lumen of the PCT, HCO 3 – combines with hydrogen ions to form carbonic acid (H 2 CO 3 ). This is enzymatically catalyzed into CO 2 and water, which diffuse across the apical membrane into the cell. Water can move osmotically across the lipid bilayer membrane due to the presence of aquaporin water channels. Inside the cell, the reverse reaction occurs to produce bicarbonate ions (HCO 3 – ). These bicarbonate ions are cotransported with Na + across the basal membrane to the interstitial space around the PCT ( Figure 25.19 ). At the same time this is occurring, a Na + /H + antiporter excretes H + into the lumen, while it recovers Na + . Note how the hydrogen ion is recycled so that bicarbonate can be recovered. Also, note that a Na + gradient is created by the Na + /K + pump. HCO 3 − + H + ↔ H 2 CO 3 ↔ CO 2  + H 2 O HCO 3 − + H + ↔ H 2 CO 3 ↔ CO 2  + H 2 O MathType@MTEF@5@5@+=feaagyart1ev2aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLnhiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq=Jc9vqaqpepm0xbba9pwe9Q8fs0=yqaqpepae9pg0FirpepeKkFr0xfr=xfr=xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaGaaeisaiaaboeacaqGpbWaaSbaaSqaaiaaiodacqGHsislaeqaaOGaae4kaiaabccacaqGibWaaWbaaSqabeaacaqGRaaaaOGaeyiLHSQaaeisamaaBaaaleaacaqGYaaabeaakiaaboeacaqGpbWaaSbaaSqaaiaabodaaeqaaOGaeyiLHSQaae4qaiaab+eadaWgaaWcbaGaaeOmaaqabaGccaqGGaGaae4kaiaabccacaqGibWaaSbaaSqaaiaabkdaaeqaaOGaae4taaaa@4C48@ The significant recovery of solutes from the PCT lumen to the interstitial space creates an osmotic gradient that promotes water recovery. As noted before, water moves through channels created by the aquaporin proteins. These proteins are found in all cells in varying amounts and help regulate water movement across membranes and through cells by creating a passageway across the hydrophobic lipid bilayer membrane. Changing the number of aquaporin proteins in membranes of the collecting ducts also helps to regulate the osmolarity of the blood. The movement of many positively charged ions also creates an electrochemical gradient. This charge promotes the movement of negative ions toward the interstitial spaces and the movement of positive ions toward the lumen. Reabsorption and Secretion in the Loop of Henle The loop of Henle consists of two sections: thick and thin descending and thin and thick ascending sections. The loops of cortical nephrons do not extend into the renal medulla very far, if at all. Juxtamedullary nephrons have loops that extend variable distances, some very deep into the medulla. The descending and ascending portions of the loop are highly specialized to enable recovery of much of the Na + and water that were filtered by the glomerulus. As the forming urine moves through the loop, the osmolarity will change from isosmotic with blood (about 278–300 mOsmol/kg) to both a very hypertonic solution of about 1200 mOsmol/kg and a very hypotonic solution of about 100 mOsmol/kg. These changes are accomplished by osmosis in the descending limb and active transport in the ascending limb. Solutes and water recovered from these loops are returned to the circulation by way of the vasa recta. Descending Loop The majority of the descending loop is comprised of simple squamous epithelial cells; to simplify the function of the loop, this discussion focuses on these cells. These membranes have permanent aquaporin channel proteins that allow unrestricted movement of water from the descending loop into the surrounding interstitium as osmolarity increases from about 300 mOsmol/kg to about 1200 mOsmol/kg. This increase results in reabsorption of up to 15 percent of the water entering the nephron. Modest amounts of urea, Na + , and other ions are also recovered here. Most of the solutes that were filtered in the glomerulus have now been recovered along with a majority of water, about 82 percent. As the forming urine enters the ascending loop, major adjustments will be made to the concentration of solutes to create what you perceive as urine. Ascending Loop The ascending loop is made of very short thin and longer thick portions. Once again, to simplify the function, this section only considers the thick portion. The thick portion is lined with simple cuboidal epithelium without a brush border. It is completely impermeable to water due to the absence of aquaporin proteins, but ions, mainly Na + and CL – , are actively reabsorbed by a cotransport system. This has two significant effects: Removal of NaCl while retaining water leads to a hypoosomotic filtrate by the time it reaches the DCT; pumping NaCl into the interstitial space contributes to the hyperosmotic environment in the kidney medulla. The Na +/ K + ATPase pumps in the basal membrane create an electrochemical gradient, allowing reabsorption of Cl – by Na + /Cl – symporters in the apical membrane. At the same time that Na + is actively pumped from the basal side of the cell into the interstitial fluid, Cl – follows the Na + from the lumen into the interstitial fluid by a paracellular route between cells through leaky tight junctions . These are found between cells of the ascending loop, where they allow certain solutes to move according to their concentration gradient. Most of the K + that enters the cell via symporters returns to the lumen (down its concentration gradient) through leaky channels in the apical membrane. Note the environment now created in the interstitial space: With the “back door exiting” K + , there is one Na + and two Cl – ions left in the interstitium surrounding the ascending loop. Therefore, in comparison to the lumen of the loop, the interstitial space is now a negatively charged environment. This negative charge attracts cations (Na + , K + , Ca ++ , and Mg ++ ) from the lumen via a paracellular route to the interstitial space and vasa recta. Countercurrent Multiplier System The structure of the loop of Henle and associated vasa recta create a countercurrent multiplier system ( Figure 25.20 ). The countercurrent term comes from the fact that the descending and ascending loops are next to each other and their fluid flows in opposite directions (countercurrent). The multiplier term is due to the action of solute pumps that increase (multiply) the concentrations of urea and Na + deep in the medulla. As discussed above, the ascending loop actively reabsorbs NaCl out of the forming urine into the interstitial spaces. In addition, collecting ducts have urea pumps that actively pump urea into the interstitial spaces. This results in the recovery of NaCl to the circulation via the vasa recta and creates a high osmolar environment in the depths of the medulla. Ammonia (NH 3 ) is a toxic byproduct of protein metabolism. It is formed as amino acids are deaminated by liver hepatocytes. That means that the amine group, NH 2 , is removed from amino acids as they are broken down. Most of the resulting ammonia is converted into urea by liver hepatocytes. Urea is not only less toxic but is utilized to aid in the recovery of water by the loop of Henle and collecting ducts. At the same time that water is freely diffusing out of the descending loop through aquaporin channels into the interstitial spaces of the medulla, urea freely diffuses into the lumen of the descending loop as it descends deeper into the medulla, much of it to be reabsorbed from the forming urine when it reaches the collecting duct. Thus, the movement of Na + and urea into the interstitial spaces by these mechanisms creates the hyperosmotic environment of the medulla. The net result of this countercurrent multiplier system is to recover both water and Na + in the circulation. The amino acid glutamine can be deaminated by the kidney. As NH 2 from the amino acid is converted into NH 3 and pumped into the lumen of the PCT, Na + and HCO 3 – are excreted into the interstitial fluid of the renal pyramid via a symport mechanism. When this process occurs in the cells of the PCT, the added benefit is a net loss of a hydrogen ion (complexed to ammonia to form the weak acid NH 4 + ) in the urine and a gain of a bicarbonate ion (HCO 3 – ) in the blood. Ammonia and bicarbonate are exchanged in a one-to-one ratio. This exchange is yet another means by which the body can buffer and excrete acid. The presence of aquaporin channels in the descending loop allows prodigious quantities of water to leave the loop and enter the hyperosmolar interstitium of the pyramid, where it is returned to the circulation by the vasa recta. As the loop turns to become the ascending loop, there is an absence of aquaporin channels, so water cannot leave the loop. However, in the basal membrane of cells of the thick ascending loop, ATPase pumps actively remove Na + from the cell. A Na + /K + /2Cl – symporter in the apical membrane passively allows these ions to enter the cell cytoplasm from the lumen of the loop down a concentration gradient created by the pump. This mechanism works to dilute the fluid of the ascending loop ultimately to approximately 50–100 mOsmol/L. At the transition from the DCT to the collecting duct, about 20 percent of the original water is still present and about 10 percent of the sodium. If no other mechanism for water reabsorption existed, about 20–25 liters of urine would be produced. Now consider what is happening in the adjacent capillaries, the vasa recta. They are recovering both solutes and water at a rate that preserves the countercurrent multiplier system. In general, blood flows slowly in capillaries to allow time for exchange of nutrients and wastes. In the vasa recta particularly, this rate of flow is important for two additional reasons. The flow must be slow to allow blood cells to lose and regain water without either crenating or bursting. Second, a rapid flow would remove too much Na + and urea, destroying the osmolar gradient that is necessary for the recovery of solutes and water. Thus, by flowing slowly to preserve the countercurrent mechanism, as the vasa recta descend, Na + and urea are freely able to enter the capillary, while water freely leaves; as they ascend, Na + and urea are secreted into the surrounding medulla, while water reenters and is removed. Interactive Link Watch this video to learn about the countercurrent multiplier system. Reabsorption and Secretion in the Distal Convoluted Tubule Approximately 80 percent of filtered water has been recovered by the time the dilute forming urine enters the DCT. The DCT will recover another 10–15 percent before the forming urine enters the collecting ducts. Aldosterone increases the amount of Na + /K + ATPase in the basal membrane of the DCT and collecting duct. The movement of Na + out of the lumen of the collecting duct creates a negative charge that promotes the movement of Cl – out of the lumen into the interstitial space by a paracellular route across tight junctions. Peritubular capillaries receive the solutes and water, returning them to the circulation. Cells of the DCT also recover Ca ++ from the filtrate. Receptors for parathyroid hormone (PTH) are found in DCT cells and when bound to PTH, induce the insertion of calcium channels on their luminal surface. The channels enhance Ca ++ recovery from the forming urine. In addition, as Na + is pumped out of the cell, the resulting electrochemical gradient attracts Ca ++ into the cell. Finally, calcitriol (1,25 dihydroxyvitamin D, the active form of vitamin D) is very important for calcium recovery. It induces the production of calcium-binding proteins that transport Ca ++ into the cell. These binding proteins are also important for the movement of calcium inside the cell and aid in exocytosis of calcium across the basolateral membrane. Any Ca ++ not reabsorbed at this point is lost in the urine. Collecting Ducts and Recovery of Water Solutes move across the membranes of the collecting ducts, which contain two distinct cell types, principal cells and intercalated cells. A principal cell possesses channels for the recovery or loss of sodium and potassium. An intercalated cell secretes or absorbs acid or bicarbonate. As in other portions of the nephron, there is an array of micromachines (pumps and channels) on display in the membranes of these cells. Regulation of urine volume and osmolarity are major functions of the collecting ducts. By varying the amount of water that is recovered, the collecting ducts play a major role in maintaining the body’s normal osmolarity. If the blood becomes hyperosmotic, the collecting ducts recover more water to dilute the blood; if the blood becomes hyposmotic, the collecting ducts recover less of the water, leading to concentration of the blood. Another way of saying this is: If plasma osmolarity rises, more water is recovered and urine volume decreases; if plasma osmolarity decreases, less water is recovered and urine volume increases. This function is regulated by the posterior pituitary hormone ADH (vasopressin). With mild dehydration, plasma osmolarity rises slightly. This increase is detected by osmoreceptors in the hypothalamus, which stimulates the release of ADH from the posterior pituitary. If plasma osmolarity decreases slightly, the opposite occurs. When stimulated by ADH, aquaporin channels are inserted into the apical membrane of principal cells, which line the collecting ducts. As the ducts descend through the medulla, the osmolarity surrounding them increases (due to the countercurrent mechanisms described above). If aquaporin water channels are present, water will be osmotically pulled from the collecting duct into the surrounding interstitial space and into the peritubular capillaries. Therefore, the final urine will be more concentrated. If less ADH is secreted, fewer aquaporin channels are inserted and less water is recovered, resulting in dilute urine. By altering the number of aquaporin channels, the volume of water recovered or lost is altered. This, in turn, regulates the blood osmolarity, blood pressure, and osmolarity of the urine. As Na + is pumped from the forming urine, water is passively recaptured for the circulation; this preservation of vascular volume is critically important for the maintenance of a normal blood pressure. Aldosterone is secreted by the adrenal cortex in response to angiotensin II stimulation. As an extremely potent vasoconstrictor, angiotensin II functions immediately to increase blood pressure. By also stimulating aldosterone production, it provides a longer-lasting mechanism to support blood pressure by maintaining vascular volume (water recovery). In addition to receptors for ADH, principal cells have receptors for the steroid hormone aldosterone. While ADH is primarily involved in the regulation of water recovery, aldosterone regulates Na + recovery. Aldosterone stimulates principal cells to manufacture luminal Na + and K + channels as well as Na + /K + ATPase pumps on the basal membrane of the cells. When aldosterone output increases, more Na + is recovered from the forming urine and water follows the Na + passively. As the pump recovers Na + for the body, it is also pumping K + into the forming urine, since the pump moves K + in the opposite direction. When aldosterone decreases, more Na + remains in the forming urine and more K + is recovered in the circulation. Symport channels move Na + and Cl – together. Still other channels in the principal cells secrete K + into the collecting duct in direct proportion to the recovery of Na + . Intercalated cells play significant roles in regulating blood pH. Intercalated cells reabsorb K + and HCO 3 – while secreting H + . This function lowers the acidity of the plasma while increasing the acidity of the urine. 25.7 Regulation of Renal Blood Flow Learning Objectives By the end of this section, you will be able to: Describe the myogenic and tubuloglomerular feedback mechanisms and explain how they affect urine volume and composition Describe the function of the juxtaglomerular apparatus It is vital that the flow of blood through the kidney be at a suitable rate to allow for filtration. This rate determines how much solute is retained or discarded, how much water is retained or discarded, and ultimately, the osmolarity of blood and the blood pressure of the body. Sympathetic Nerves The kidneys are innervated by the sympathetic neurons of the autonomic nervous system via the celiac plexus and splanchnic nerves. Reduction of sympathetic stimulation results in vasodilation and increased blood flow through the kidneys during resting conditions. When the frequency of action potentials increases, the arteriolar smooth muscle constricts (vasoconstriction), resulting in diminished glomerular flow, so less filtration occurs. Under conditions of stress, sympathetic nervous activity increases, resulting in the direct vasoconstriction of afferent arterioles (norepinephrine effect) as well as stimulation of the adrenal medulla. The adrenal medulla, in turn, produces a generalized vasoconstriction through the release of epinephrine. This includes vasoconstriction of the afferent arterioles, further reducing the volume of blood flowing through the kidneys. This process redirects blood to other organs with more immediate needs. If blood pressure falls, the sympathetic nerves will also stimulate the release of renin. Additional renin increases production of the powerful vasoconstrictor angiotensin II. Angiotensin II, as discussed above, will also stimulate aldosterone production to augment blood volume through retention of more Na + and water. Only a 10 mm Hg pressure differential across the glomerulus is required for normal GFR, so very small changes in afferent arterial pressure significantly increase or decrease GFR. Autoregulation The kidneys are very effective at regulating the rate of blood flow over a wide range of blood pressures. Your blood pressure will decrease when you are relaxed or sleeping. It will increase when exercising. Yet, despite these changes, the filtration rate through the kidney will change very little. This is due to two internal autoregulatory mechanisms that operate without outside influence: the myogenic mechanism and the tubuloglomerular feedback mechanism. Arteriole Myogenic Mechanism The myogenic mechanism regulating blood flow within the kidney depends upon a characteristic shared by most smooth muscle cells of the body. When you stretch a smooth muscle cell, it contracts; when you stop, it relaxes, restoring its resting length. This mechanism works in the afferent arteriole that supplies the glomerulus. When blood pressure increases, smooth muscle cells in the wall of the arteriole are stretched and respond by contracting to resist the pressure, resulting in little change in flow. When blood pressure drops, the same smooth muscle cells relax to lower resistance, allowing a continued even flow of blood. Tubuloglomerular Feedback The tubuloglomerular feedback mechanism involves the JGA and a paracrine signaling mechanism utilizing ATP, adenosine, and nitric oxide (NO). This mechanism stimulates either contraction or relaxation of afferent arteriolar smooth muscle cells ( Table 25.7 ). Recall that the DCT is in intimate contact with the afferent and efferent arterioles of the glomerulus. Specialized macula densa cells in this segment of the tubule respond to changes in the fluid flow rate and Na + concentration. As GFR increases, there is less time for NaCl to be reabsorbed in the PCT, resulting in higher osmolarity in the filtrate. The increased fluid movement more strongly deflects single nonmotile cilia on macula densa cells. This increased osmolarity of the forming urine, and the greater flow rate within the DCT, activates macula densa cells to respond by releasing ATP and adenosine (a metabolite of ATP). ATP and adenosine act locally as paracrine factors to stimulate the myogenic juxtaglomerular cells of the afferent arteriole to constrict, slowing blood flow and reducing GFR. Conversely, when GFR decreases, less Na + is in the forming urine, and most will be reabsorbed before reaching the macula densa, which will result in decreased ATP and adenosine, allowing the afferent arteriole to dilate and increase GFR. NO has the opposite effect, relaxing the afferent arteriole at the same time ATP and adenosine are stimulating it to contract. Thus, NO fine-tunes the effects of adenosine and ATP on GFR. Paracrine Mechanisms Controlling Glomerular Filtration Rate Change in GFR NaCl Absorption Role of ATP and adenosine/Role of NO Effect on GFR Increased GFR Tubular NaCl increases ATP and adenosine increase, causing vasoconstriction Vasoconstriction slows GFR Decreased GFR Tubular NaCl decreases ATP and adenosine decrease, causing vasodilation Vasodilation increases GFR Increased GFR Tubular NaCl increases NO increases, causing vasodilation Vasodilation increases GFR Decreased GFR Tubular NaCl decreases NO decreases, causing vasoconstricton Vasoconstriction decreases GFR Table 25.7 25.8 Endocrine Regulation of Kidney Function Learning Objectives By the end of this section, you will be able to: Describe how each of the following functions in the extrinsic control of GFR: renin–angiotensin mechanism, natriuretic peptides, and sympathetic adrenergic activity Describe how each of the following works to regulate reabsorption and secretion, so as to affect urine volume and composition: renin–angiotensin system, aldosterone, antidiuretic hormone, and natriuretic peptides Name and define the roles of other hormones that regulate kidney control Several hormones have specific, important roles in regulating kidney function. They act to stimulate or inhibit blood flow. Some of these are endocrine, acting from a distance, whereas others are paracrine, acting locally. Renin–Angiotensin–Aldosterone Renin is an enzyme that is produced by the granular cells of the afferent arteriole at the JGA. It enzymatically converts angiotensinogen (made by the liver, freely circulating) into angiotensin I. Its release is stimulated by prostaglandins and NO from the JGA in response to decreased extracellular fluid volume. ACE is not a hormone but it is functionally important in regulating systemic blood pressure and kidney function. It is produced in the lungs but binds to the surfaces of endothelial cells in the afferent arterioles and glomerulus. It enzymatically converts inactive angiotensin I into active angiotensin II. ACE is important in raising blood pressure. People with high blood pressure are sometimes prescribed ACE inhibitors to lower their blood pressure. Angiotensin II is a potent vasoconstrictor that plays an immediate role in the regulation of blood pressure. It acts systemically to cause vasoconstriction as well as constriction of both the afferent and efferent arterioles of the glomerulus. In instances of blood loss or dehydration, it reduces both GFR and renal blood flow, thereby limiting fluid loss and preserving blood volume. Its release is usually stimulated by decreases in blood pressure, and so the preservation of adequate blood pressure is its primary role. Aldosterone, often called the “salt-retaining hormone,” is released from the adrenal cortex in response to angiotensin II or directly in response to increased plasma K + . It promotes Na + reabsorption by the nephron, promoting the retention of water. It is also important in regulating K + , promoting its excretion. (This dual effect on two minerals and its origin in the adrenal cortex explains its designation as a mineralocorticoid.) As a result, renin has an immediate effect on blood pressure due to angiotensin II–stimulated vasoconstriction and a prolonged effect through Na + recovery due to aldosterone. At the same time that aldosterone causes increased recovery of Na + , it also causes greater loss of K + . Progesterone is a steroid that is structurally similar to aldosterone. It binds to the aldosterone receptor and weakly stimulates Na + reabsorption and increased water recovery. This process is unimportant in men due to low levels of circulating progesterone. It may cause increased retention of water during some periods of the menstrual cycle in women when progesterone levels increase. Antidiuretic Hormone (ADH) Diuretics are drugs that can increase water loss by interfering with the recapture of solutes and water from the forming urine. They are often prescribed to lower blood pressure. Coffee, tea, and alcoholic beverages are familiar diuretics. ADH, a 9-amino acid peptide released by the posterior pituitary, works to do the exact opposite. It promotes the recovery of water, decreases urine volume, and maintains plasma osmolarity and blood pressure. It does so by stimulating the movement of aquaporin proteins into the apical cell membrane of principal cells of the collecting ducts to form water channels, allowing the transcellular movement of water from the lumen of the collecting duct into the interstitial space in the medulla of the kidney by osmosis. From there, it enters the vasa recta capillaries to return to the circulation. Water is attracted by the high osmotic environment of the deep kidney medulla. Endothelin Endothelins , 21-amino acid peptides, are extremely powerful vasoconstrictors. They are produced by endothelial cells of the renal blood vessels, mesangial cells, and cells of the DCT. Hormones stimulating endothelin release include angiotensin II, bradykinin, and epinephrine. They do not typically influence blood pressure in healthy people. On the other hand, in people with diabetic kidney disease, endothelin is chronically elevated, resulting in sodium retention. They also diminish GFR by damaging the podocytes and by potently vasoconstricting both the afferent and efferent arterioles. Natriuretic Hormones Natriuretic hormones are peptides that stimulate the kidneys to excrete sodium—an effect opposite that of aldosterone. Natriuretic hormones act by inhibiting aldosterone release and therefore inhibiting Na + recovery in the collecting ducts. If Na + remains in the forming urine, its osmotic force will cause a concurrent loss of water. Natriuretic hormones also inhibit ADH release, which of course will result in less water recovery. Therefore, natriuretic peptides inhibit both Na + and water recovery. One example from this family of hormones is atrial natriuretic hormone (ANH), a 28-amino acid peptide produced by heart atria in response to over-stretching of the atrial wall. The over-stretching occurs in persons with elevated blood pressure or heart failure. It increases GFR through concurrent vasodilation of the afferent arteriole and vasoconstriction of the efferent arteriole. These events lead to an increased loss of water and sodium in the forming urine. It also decreases sodium reabsorption in the DCT. There is also B-type natriuretic peptide (BNP) of 32 amino acids produced in the ventricles of the heart. It has a 10-fold lower affinity for its receptor, so its effects are less than those of ANH. Its role may be to provide “fine tuning” for the regulation of blood pressure. BNP’s longer biologic half-life makes it a good diagnostic marker of congestive heart failure ( Figure 25.21 ). Parathyroid Hormone Parathyroid hormone (PTH) is an 84-amino acid peptide produced by the parathyroid glands in response to decreased circulating Ca ++ levels. Among its targets is the PCT, where it stimulates the hydroxylation of calcidiol to calcitriol (1,25-hydroxycholecalciferol, the active form of vitamin D). It also blocks reabsorption of phosphate (PO 3 – ), causing its loss in the urine. The retention of phosphate would result in the formation of calcium phosphate in the plasma, reducing circulating Ca ++ levels. By ridding the blood of phosphate, higher circulating Ca ++ levels are permitted. 25.9 Regulation of Fluid Volume and Composition Learning Objectives By the end of this section, you will be able to: Explain the mechanism of action of diuretics Explain why the differential permeability or impermeability of specific sections of the nephron tubules is necessary for urine formation The major hormones influencing total body water are ADH, aldosterone, and ANH. Circumstances that lead to fluid depletion in the body include blood loss and dehydration. Homeostasis requires that volume and osmolarity be preserved. Blood volume is important in maintaining sufficient blood pressure, and there are nonrenal mechanisms involved in its preservation, including vasoconstriction, which can act within seconds of a drop in pressure. Thirst mechanisms are also activated to promote the consumption of water lost through respiration, evaporation, or urination. Hormonal mechanisms are activated to recover volume while maintaining a normal osmotic environment. These mechanisms act principally on the kidney. Volume-sensing Mechanisms The body cannot directly measure blood volume, but blood pressure can be measured. Blood pressure often reflects blood volume and is measured by baroreceptors in the aorta and carotid sinuses. When blood pressure increases, baroreceptors send more frequent action potentials to the central nervous system, leading to widespread vasodilation. Included in this vasodilation are the afferent arterioles supplying the glomerulus, resulting in increased GFR, and water loss by the kidneys. If pressure decreases, fewer action potentials travel to the central nervous system, resulting in more sympathetic stimulation-producing vasoconstriction, which will result in decreased filtration and GFR, and water loss. Decreased blood pressure is also sensed by the granular cells in the afferent arteriole of the JGA. In response, the enzyme renin is released. You saw earlier in the chapter that renin activity leads to an almost immediate rise in blood pressure as activated angiotensin II produces vasoconstriction. The rise in pressure is sustained by the aldosterone effects initiated by angiotensin II; this includes an increase in Na + retention and water volume. As an aside, late in the menstrual cycle, progesterone has a modest influence on water retention. Due to its structural similarity to aldosterone, progesterone binds to the aldosterone receptor in the collecting duct of the kidney, causing the same, albeit weaker, effect on Na + and water retention. Cardiomyocytes of the atria also respond to greater stretch (as blood pressure rises) by secreting ANH. ANH opposes the action of aldosterone by inhibiting the recovery of Na + by the DCT and collecting ducts. More Na + is lost, and as water follows, total blood volume and pressure decline. In low-pressure states, ANH does not seem to have much effect. ADH is also called vasopressin. Early researchers found that in cases of unusually high secretion of ADH, the hormone caused vasoconstriction (vasopressor activity, hence the name). Only later were its antidiuretic properties identified. Synthetic ADH is still used occasionally to stem life-threatening esophagus bleeding in alcoholics. When blood volume drops 5–10 percent, causing a decrease in blood pressure, there is a rapid and significant increase in ADH release from the posterior pituitary. Immediate vasoconstriction to increase blood pressure is the result. ADH also causes activation of aquaporin channels in the collecting ducts to affect the recovery of water to help restore vascular volume. Diuretics and Fluid Volume A diuretic is a compound that increases urine volume. Three familiar drinks contain diuretic compounds: coffee, tea, and alcohol. The caffeine in coffee and tea works by promoting vasodilation in the nephron, which increases GFR. Alcohol increases GFR by inhibiting ADH release from the posterior pituitary, resulting in less water recovery by the collecting duct. In cases of high blood pressure, diuretics may be prescribed to reduce blood volume and, thereby, reduce blood pressure. The most frequently prescribed anti-hypertensive diuretic is hydrochlorothiazide. It inhibits the Na + / Cl – symporter in the DCT and collecting duct. The result is a loss of Na + with water following passively by osmosis. Osmotic diuretics promote water loss by osmosis. An example is the indigestible sugar mannitol, which is most often administered to reduce brain swelling after head injury. However, it is not the only sugar that can produce a diuretic effect. In cases of poorly controlled diabetes mellitus, glucose levels exceed the capacity of the tubular glucose symporters, resulting in glucose in the urine. The unrecovered glucose becomes a powerful osmotic diuretic. Classically, in the days before glucose could be detected in the blood and urine, clinicians identified diabetes mellitus by the three Ps: polyuria (diuresis), polydipsia (increased thirst), and polyphagia (increased hunger). Regulation of Extracellular Na + Sodium has a very strong osmotic effect and attracts water. It plays a larger role in the osmolarity of the plasma than any other circulating component of the blood. If there is too much Na + present, either due to poor control or excess dietary consumption, a series of metabolic problems ensue. There is an increase in total volume of water, which leads to hypertension (high blood pressure). Over a long period, this increases the risk of serious complications such as heart attacks, strokes, and aneurysms. It can also contribute to system-wide edema (swelling). Mechanisms for regulating Na + concentration include the renin–angiotensin–aldosterone system and ADH (see Figure 25.14 ). Aldosterone stimulates the uptake of Na + on the apical cell membrane of cells in the DCT and collecting ducts, whereas ADH helps to regulate Na + concentration indirectly by regulating the reabsorption of water. Regulation of Extracellular K + Potassium is present in a 30-fold greater concentration inside the cell than outside the cell. A generalization can be made that K + and Na + concentrations will move in opposite directions. When more Na + is reabsorbed, more K + is secreted; when less Na + is reabsorbed (leading to excretion by the kidney), more K + is retained. When aldosterone causes a recovery of Na + in the nephron, a negative electrical gradient is created that promotes the secretion of K + and Cl – into the lumen. Regulation of Cl – Chloride is important in acid–base balance in the extracellular space and has other functions, such as in the stomach, where it combines with hydrogen ions in the stomach lumen to form hydrochloric acid, aiding digestion. Its close association with Na + in the extracellular environment makes it the dominant anion of this compartment, and its regulation closely mirrors that of Na + . Regulation of Ca ++ and Phosphate The parathyroid glands monitor and respond to circulating levels of Ca ++ in the blood. When levels drop too low, PTH is released to stimulate the DCT to reabsorb Ca ++ from the forming urine. When levels are adequate or high, less PTH is released and more Ca ++ remains in the forming urine to be lost. Phosphate levels move in the opposite direction. When Ca ++ levels are low, PTH inhibits reabsorption of HPO 4 2 − HPO 4 2 − MathType@MTEF@5@5@+=feaagyart1ev2aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLnhiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq=Jc9vqaqpepm0xbba9pwe9Q8fs0=yqaqpepae9pg0FirpepeKkFr0xfr=xfr=xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaGaaeisaiaabcfacaqGpbWaa0baaSqaaiaaisdaaeaacaaIYaGaeyOeI0caaaaa@3AF7@ so that its blood level drops, allowing Ca ++ levels to rise. PTH also stimulates the renal conversion of calcidiol into calcitriol, the active form of vitamin D. Calcitriol then stimulates the intestines to absorb more Ca ++ from the diet. Regulation of H + , Bicarbonate, and pH The acid–base homeostasis of the body is a function of chemical buffers and physiologic buffering provided by the lungs and kidneys. Buffers, especially proteins, HCO 3 − HCO 3 − MathType@MTEF@5@5@+=feaagyart1ev2aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLnhiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq=Jc9vqaqpepm0xbba9pwe9Q8fs0=yqaqpepae9pg0FirpepeKkFr0xfr=xfr=xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaGaaeisaiaaboeacaqGpbWaa0baaSqaaiaaiodaaeaacaaIYaGaeyOeI0caaaaa@3AE9@ , and ammonia have a very large capacity to absorb or release H + as needed to resist a change in pH. They can act within fractions of a second. The lungs can rid the body of excess acid very rapidly (seconds to minutes) through the conversion of HCO 3 – into CO 2 , which is then exhaled. It is rapid but has limited capacity in the face of a significant acid challenge. The kidneys can rid the body of both acid and base. The renal capacity is large but slow (minutes to hours). The cells of the PCT actively secrete H + into the forming urine as Na + is reabsorbed. The body rids itself of excess H + and raises blood pH. In the collecting ducts, the apical surfaces of intercalated cells have proton pumps that actively secrete H + into the luminal, forming urine to remove it from the body. As hydrogen ions are pumped into the forming urine, it is buffered by bicarbonate (HCO 3 – ), H 2 PO 4 – (dihydrogen phosphate ion), or ammonia (forming NH 4 + , ammonium ion). Urine pH typically varies in a normal range from 4.5 to 8.0. Regulation of Nitrogen Wastes Nitrogen wastes are produced by the breakdown of proteins during normal metabolism. Proteins are broken down into amino acids, which in turn are deaminated by having their nitrogen groups removed. Deamination converts the amino (NH 2 ) groups into ammonia (NH 3 ), ammonium ion (NH 4 + ), urea, or uric acid ( Figure 25.22 ). Ammonia is extremely toxic, so most of it is very rapidly converted into urea in the liver. Human urinary wastes typically contain primarily urea with small amounts of ammonium and very little uric acid. Elimination of Drugs and Hormones Water-soluble drugs may be excreted in the urine and are influenced by one or all of the following processes: glomerular filtration, tubular secretion, or tubular reabsorption. Drugs that are structurally small can be filtered by the glomerulus with the filtrate. Large drug molecules such as heparin or those that are bound to plasma proteins cannot be filtered and are not readily eliminated. Some drugs can be eliminated by carrier proteins that enable secretion of the drug into the tubule lumen. There are specific carriers that eliminate basic (such as dopamine or histamine) or acidic drugs (such as penicillin or indomethacin). As is the case with other substances, drugs may be both filtered and reabsorbed passively along a concentration gradient.
introduction_to_sociology
Learning Objectives 20.1 Demography and Population Understand demographic measurements like fertility and mortality rates Describe a variety of demographic theories, such as Malthusian, cornucopian, zero population growth, and demographic transition theories Be familiar with current population trends and patterns 20.2 Urbanization Describe the process of urbanization in the United States Understand the function of suburbs, exurbs, and concentric zones Discuss urbanization from various sociological perspectives 20.3 The Environment and Society Apply the concept of carrying capacity to environmental concerns Understand the challenges presented by pollution, garbage, e-waste, and toxic hazards Describe climate change and its importance Discuss real-world instances of environmental racism Introduction to Population, Urbanization, and the Environment There used to be a place called Centralia, Pennsylvania. Some current maps might still show the town, which was on Route 61 in the heart of Pennsylvania’s coal region. But many others have removed the defunct town from atlases, despite the fact that there are still a few die-hard residents there. The town incorporated in the 1860s and once had several thousand residents, largely coal workers. But the story of its demise begins a century later, in 1962. That year, a trash-burning fire was lit in the pit of the old abandoned coalmine outside of town. The fire moved down the mineshaft and ignited a vein of coal. That fire is still burning. Of course, some initial efforts were made to put out the fire, both above ground and below. But it continued to burn a few days later. It was put out again, and again it flared up. This is when it traveled down the vein and ignited the coal deposit beneath the ground. For more than 20 years, people tried to extinguish the underground fire, but no matter what they did, it returned. There was little government action, and people had to abandon their homes as toxic gases engulfed the area and sinkholes developed. The situation drew national attention when the ground collapsed under 12-year-old Todd Domboski in 1981. He was in his yard when a sinkhole four feet wide and 150 feet deep opened up beneath him. He clung to exposed tree roots and saved his life; if he had fallen a few feet farther, the heat or carbon monoxide would have killed him instantly. In 1983, engineers studying the fire concluded that it could burn for another century or more, and could spread over nearly 4,000 acres. At this point, the government offered to “buy out” existing residents, relocating them to nearby towns. A few determined Centralians refused, and they are the only ones who remain. In one field, signs warn people to enter at their own risk, as the ground is hot and unstable. As we examine population, urbanization, and the environment, we will see how these subjects relate to Centralia. Environmental disaster. Abandoned ghost town. A population forced from their homes. Today, the few stalwart residents refuse to leave, but the government owns their homes. And the fire burns on (DeKok 1986). Many of you have seen the 2000 movie, Erin Brokovich , about a legal assistant who spearheads a $300 million lawsuit against a California power company. The story is true, and the town of Hinkley, California, is an example of a cancer cluster , a geographic area with proportionately higher cancer rates (in the Erin Brokovich case caused by a toxin leaked into the groundwater) . It can be very challenging to go up against major governmental or corporate interests, and the Hinkley case is an inspiring example of success; however, the damage wrought on that area’s population cannot be undone. As the stories of Centralia and Hinkley illustrate, there are important societal issues connected to the environment and how and where people live. Sociologists begin to examine these issues through demography, or the study of population, and how it relates to urbanization, the study of the social, political, and economic relationships in cities. Environmental sociologists look at the study of how humans interact with their environments. Today, as has been the case many times in history, we are at a point of conflict in a number of these areas. The world’s population has recently reached seven billion. When will it reach eight billion? Can our planet sustain such a population? We generate more trash than ever, from Starbucks cups to obsolete cell phones with toxic chemicals to food waste that could be composted. Where it is all going? Chances are that you are likely unaware of where your trash ends up. And while this problem exists worldwide, trash issues are often more acute in urban areas. Cities and city living create new challenges for both society and the environment. These kinds of interactions between people and places are of critical importance. How do sociologists study these issues? A functionalist sociologist might focus on the way that all aspects of population, urbanization, and the environment serve as vital and cohesive elements, ensuring the continuing stability of society. A functionalist might study how the growth of the global population encourages emigration and immigration, and how emigration and immigration serve to strengthen ties between nations. Or she might research how migration impacts environmental issues; for example, how have forced migrations, and the resulting changes in a region’s ability to support a new people group, affected both the displaced people and the area of relocation? Another topic a functionalist might research is the way that various urban neighborhoods specialize to serve cultural and financial needs. A conflict theorist, interested in the creation and reproduction of inequality, might ask how peripheral nations’ lack of family planning impacts the overall population in comparison to core nations that tend to have lower fertility rates? Or, how do inner cities become ghettos, nearly devoid of jobs, education, and other opportunities? A conflict theorist might also study environmental racism and other forms of environmental inequality. For example, looking at Hurricane Katrina, which parts of New Orleans’ society were the most responsive to the evacuation order? Which area was most affected by the flooding? And where (and in what conditions) were people living in those areas housed, both during and before the evacuation? A symbolic interactionist interested in the day-to-day interaction of groups and individuals might research topics like how family-planning information is presented to and understood by different population groups, how people experience and understand urban life, and what language people use to convince others of the presence (or absence) of global climate change. For example, some politicians wish to present the study of global warming as junk science, and other politicians insist it is a proven fact.
[ { "answer": { "ans_choice": 0, "ans_text": "6 billion" }, "bloom": null, "hl_context": "As mentioned earlier , the earth ’ s population is seven billion . That number might not seem particularly jarring on its own ; after all , we all know there are lots of people around . <hl> But consider the fact that human population grew very slowly for most of our existence , then doubled in the span of half a century to reach six billion in 1999 . <hl> And now , just over ten years later , we have added another billion . A look at the graph of projected population indicates that growth is not only going to continue , but it will continue at a rapid rate .", "hl_sentences": "But consider the fact that human population grew very slowly for most of our existence , then doubled in the span of half a century to reach six billion in 1999 .", "question": { "cloze_format": "The population of the planet doubled in 50 years to reach _______ in 1999?", "normal_format": "The population of the planet doubled in 50 years to reach which of the following in 1999?", "question_choices": [ "6 billion", "7 billion", "5 billion", "10 billion" ], "question_id": "fs-id3634219", "question_text": "The population of the planet doubled in 50 years to reach _______ in 1999?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 1, "ans_text": "The way that immigration and emigration trends strengthen global relationships" }, "bloom": "1", "hl_context": "Many of you have seen the 2000 movie , Erin Brokovich , about a legal assistant who spearheads a $ 300 million lawsuit against a California power company . The story is true , and the town of Hinkley , California , is an example of a cancer cluster , a geographic area with proportionately higher cancer rates ( in the Erin Brokovich case caused by a toxin leaked into the groundwater ) . It can be very challenging to go up against major governmental or corporate interests , and the Hinkley case is an inspiring example of success ; however , the damage wrought on that area ’ s population cannot be undone . As the stories of Centralia and Hinkley illustrate , there are important societal issues connected to the environment and how and where people live . Sociologists begin to examine these issues through demography , or the study of population , and how it relates to urbanization , the study of the social , political , and economic relationships in cities . Environmental sociologists look at the study of how humans interact with their environments . Today , as has been the case many times in history , we are at a point of conflict in a number of these areas . The world ’ s population has recently reached seven billion . When will it reach eight billion ? Can our planet sustain such a population ? We generate more trash than ever , from Starbucks cups to obsolete cell phones with toxic chemicals to food waste that could be composted . Where it is all going ? Chances are that you are likely unaware of where your trash ends up . And while this problem exists worldwide , trash issues are often more acute in urban areas . Cities and city living create new challenges for both society and the environment . These kinds of interactions between people and places are of critical importance . How do sociologists study these issues ? A functionalist sociologist might focus on the way that all aspects of population , urbanization , and the environment serve as vital and cohesive elements , ensuring the continuing stability of society . <hl> A functionalist might study how the growth of the global population encourages emigration and immigration , and how emigration and immigration serve to strengthen ties between nations . <hl> Or she might research how migration impacts environmental issues ; for example , how have forced migrations , and the resulting changes in a region ’ s ability to support a new people group , affected both the displaced people and the area of relocation ? Another topic a functionalist might research is the way that various urban neighborhoods specialize to serve cultural and financial needs .", "hl_sentences": "A functionalist might study how the growth of the global population encourages emigration and immigration , and how emigration and immigration serve to strengthen ties between nations .", "question": { "cloze_format": "The issue that a functionalist would address is ___ .", "normal_format": "A functionalist would address which issue?", "question_choices": [ "The way that inner city areas become ghettoized and limit availability to jobs", "The way that immigration and emigration trends strengthen global relationships", "How racism and sexism impact the population composition of rural communities ", "The way that humans interact with environmental resources on a daily basis" ], "question_id": "fs-id3021680", "question_text": "A functionalist would address which issue?" }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 2, "ans_text": "The amount of life that can be supported sustainably in a particular environment" }, "bloom": "1", "hl_context": "The subfield of environmental sociology studies how humans interact with their environments . This field is closely related to human ecology , which focuses on the relationship between people and their built and natural environment . This is an area that is garnering more attention as extreme weather patterns and policy battles over climate change dominate the news . <hl> A key factor of environmental sociology is the concept of carrying capacity , which refers to the maximum amount of life that can be sustained within a given area . <hl> While this concept can refer to grazing lands or to rivers , it also can be applied to the earth as a whole .", "hl_sentences": "A key factor of environmental sociology is the concept of carrying capacity , which refers to the maximum amount of life that can be sustained within a given area .", "question": { "cloze_format": "Carrying capacity refers to ___.", "normal_format": "What does carrying capacity refer to?", "question_choices": [ "The ability of a community to welcome new immigrants", "The capacity for globalism within a given ethnic group", "The amount of life that can be supported sustainably in a particular environment", "The amount of weight that urban centers can bear if vertical growth is mandated" ], "question_id": "fs-id3021644", "question_text": "What does carrying capacity refer to?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 3, "ans_text": "War, famine, and disease" }, "bloom": "1", "hl_context": "<hl> Thomas Malthus ( 1766 – 1834 ) was an English clergyman who made dire predictions about earth ’ s ability to sustain its growing population . <hl> According to Malthusian theory , three factors would control human population that exceeded the earth ’ s carrying capacity , or how many people can live in a given area considering the amount of available resources . <hl> He identified these factors as war , famine , and disease ( Malthus 1798 ) . <hl> He termed these “ positive checks ” because they increased mortality rates , thus keeping the population in check , so to speak . These are countered by “ preventative checks , ” which also seek to control the population , but by reducing fertility rates ; preventive checks include birth control and celibacy . Thinking practically , Malthus saw that people could only produce so much food in a given year , yet the population was increasing at an exponential rate . Eventually , he thought people would run out of food and begin to starve . They would go to war over the increasingly scarce resources , reduce the population to a manageable level , and the cycle would begin anew .", "hl_sentences": "Thomas Malthus ( 1766 – 1834 ) was an English clergyman who made dire predictions about earth ’ s ability to sustain its growing population . He identified these factors as war , famine , and disease ( Malthus 1798 ) .", "question": { "cloze_format": "___ are the three factors that Malthus believed would limit human population.", "normal_format": "What three factors did Malthus believe would limit human population?", "question_choices": [ "Self-preservation, old age, and illness", "Natural cycles, illness, and immigration", "Violence, new diseases, and old age", "War, famine, and disease" ], "question_id": "fs-id3062106", "question_text": "What three factors did Malthus believe would limit human population?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 0, "ans_text": "That human ingenuity will solve any issues that overpopulation creates" }, "bloom": null, "hl_context": "Of course , some theories are less focused on the pessimistic hypothesis that the world ’ s population will meet a detrimental challenge to sustaining itself . <hl> Cornucopian theory scoffs at the idea of humans wiping themselves out ; it asserts that human ingenuity can resolve any environmental or social issues that develop . <hl> As an example , it points to the issue of food supply . If we need more food , the theory contends , agricultural scientists will figure out how to grow it , as they have already been doing for centuries . After all , in this perspective , human ingenuity has been up to the task for thousands of years and there is no reason for that pattern not to continue ( Simon 1981 ) .", "hl_sentences": "Cornucopian theory scoffs at the idea of humans wiping themselves out ; it asserts that human ingenuity can resolve any environmental or social issues that develop .", "question": { "cloze_format": "The cornucopian theory believes ___.", "normal_format": "What does cornucopian theory believe?", "question_choices": [ "That human ingenuity will solve any issues that overpopulation creates", "That new diseases will always keep populations stable", "That the earth will naturally provide enough for whatever number of humans exist ", "That the greatest risk is population reduction, not population growth" ], "question_id": "fs-id2351171", "question_text": "What does cornucopian theory believe?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 2, "ans_text": "Formerly wealthy homes split into cheap apartments" }, "bloom": "3", "hl_context": "The concentric zone model ( Burgess 1925 ) is perhaps the most famous example of human ecology . This model views a city as a series of concentric circular areas , expanding outward from the center of the city , with various “ zones ” invading ( new categories of people and businesses overrun the edges of nearby zones ) and succeeding ( after invasion , the new inhabitants repurpose the areas they have invaded and push out the previous inhabitants ) adjacent zones . In this model , Zone A , in the heart of the city , is the center of the business and cultural district . <hl> Zone B , the concentric circle surrounding the city center , is composed of formerly wealthy homes split into cheap apartments for new immigrant populations ; this zone also houses small manufacturers , pawn shops , and other marginal businesses . <hl> Zone C consists of the homes of the working class and established ethnic enclaves . Zone D consists of wealthy homes , white-collar workers , and shopping centers . Zone E contains the estates of the upper class ( exurbs ) and the suburbs .", "hl_sentences": "Zone B , the concentric circle surrounding the city center , is composed of formerly wealthy homes split into cheap apartments for new immigrant populations ; this zone also houses small manufacturers , pawn shops , and other marginal businesses .", "question": { "cloze_format": "In the Concentric Zone model, Zone B is likely to house ___ .", "normal_format": "In the Concentric Zone model, Zone B is likely to house what?", "question_choices": [ "The city’s industrial center", "Wealthy commuter homes", "Formerly wealthy homes split into cheap apartments", "Rural outposts" ], "question_id": "fs-id1336843", "question_text": "In the Concentric Zone model, Zone B is likely to house what?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 3, "ans_text": "All of the above" }, "bloom": "1", "hl_context": "<hl> According to sociologist Gideon Sjoberg ( 1965 ) , there are three prerequisites for the development of a city . <hl> <hl> First , good environment with fresh water and a favorable climate ; second , advanced technology , which will produce a food surplus to support non-farmers ; and third , strong social organization to ensure social stability and a stable economy . <hl> Most scholars agree that the first cities were developed somewhere in ancient Mesopotamia , though there are disagreements about exactly where . Most early cities were small by today ’ s standards , and the largest city at the time was most likely Rome , with about 650,000 inhabitants ( Chandler and Fox 1974 ) . The factors limiting the size of ancient cities included lack of adequate sewage control , limited food supply , and immigration restrictions . For example , serfs were tied to the land , and transportation was limited and inefficient . Today , the primary influence on cities ’ growth is economic forces . Since the recent economic recession has reduced housing prices , researchers are waiting to see what happens to urban migration patterns in response .", "hl_sentences": "According to sociologist Gideon Sjoberg ( 1965 ) , there are three prerequisites for the development of a city . First , good environment with fresh water and a favorable climate ; second , advanced technology , which will produce a food surplus to support non-farmers ; and third , strong social organization to ensure social stability and a stable economy .", "question": { "cloze_format": "The prerequisites for the existence of a city are a(n) ___ .", "normal_format": "What are the prerequisites for the existence of a city?", "question_choices": [ "Good environment with water and a favorable climate", "Advanced agricultural technology ", "Strong social organization", "All of the above" ], "question_id": "fs-id1391063", "question_text": "What are the prerequisites for the existence of a city?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 2, "ans_text": "The Chicago meatpacking industry" }, "bloom": null, "hl_context": "<hl> Upton Sinclair ’ s The Jungle ( 1906 ) offers a snapshot of the rapid change taking place at the time . <hl> <hl> In the book , Sinclair explored the difficult living conditions and hideous and unsafe working conditions in a Chicago-area meatpacking plant . <hl> <hl> The book brought the plight of the urban working poor to the front and center of the public ’ s eye , as well as turning the stomachs of most modern readers with its graphic discussion of food preparation before the advent of government regulation . <hl>", "hl_sentences": "Upton Sinclair ’ s The Jungle ( 1906 ) offers a snapshot of the rapid change taking place at the time . In the book , Sinclair explored the difficult living conditions and hideous and unsafe working conditions in a Chicago-area meatpacking plant . The book brought the plight of the urban working poor to the front and center of the public ’ s eye , as well as turning the stomachs of most modern readers with its graphic discussion of food preparation before the advent of government regulation .", "question": { "cloze_format": "Upton Sinclair’s The Jungle examines the circumstances of the working poor people in the area of ___.", "normal_format": "Upton Sinclair’s The Jungle examines the circumstances of the working poor people in what area?", "question_choices": [ "The jungles of Africa", "An American farm", "The Chicago meatpacking industry", "A New England mill town" ], "question_id": "fs-id1584332", "question_text": "Upton Sinclair’s The Jungle examines the circumstances of the working poor people in what area?" }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 0, "ans_text": "Urban sprawl and crowds moving into the city" }, "bloom": "1", "hl_context": "<hl> As the suburbs became more crowded and lost their charm , those who could afford it turned to the exurbs , communities that exist outside the ring of suburbs and are typically populated by even wealthier families who want more space and have the resources to lengthen their commute . <hl> Together , the suburbs , exurbs , and metropolitan areas all combine to form a metropolis . New York was the first American megalopolis , a huge urban corridor encompassing multiple cities and their surrounding suburbs . These metropolises use vast quantities of natural resources and are a growing part of the U . S . landscape . As cities grew more crowded , and often more impoverished and costly , more and more people began to migrate back out of them . But instead of returning to rural small towns ( like they ’ d resided in before moving to the city ) , these people needed close access to the cities for their jobs . In the 1850s , as the urban population greatly expanded and transportation options improved , suburbs developed . <hl> Suburbs are the communities surrounding cities , typically close enough for a daily commute in , but far enough away to allow for more space than city living affords . <hl> The bucolic suburban landscape of the early 20th century has largely disappeared due to sprawl . <hl> Suburban sprawl contributes to traffic congestion , which in turn contributes to commuting time . <hl> And commuting times and distances have continued to increase as new suburbs developed farther and farther from city centers . Simultaneously , this dynamic contributed to an exponential increase in natural resource use , like petroleum , which sequentially increased pollution in the form of carbon emissions .", "hl_sentences": "As the suburbs became more crowded and lost their charm , those who could afford it turned to the exurbs , communities that exist outside the ring of suburbs and are typically populated by even wealthier families who want more space and have the resources to lengthen their commute . Suburbs are the communities surrounding cities , typically close enough for a daily commute in , but far enough away to allow for more space than city living affords . Suburban sprawl contributes to traffic congestion , which in turn contributes to commuting time .", "question": { "cloze_format": "___ led to the creation of the exurbs.", "normal_format": "What led to the creation of the exurbs?", "question_choices": [ "Urban sprawl and crowds moving into the city", "The high cost of suburban living", "The housing boom of the 1980s", "Gentrification" ], "question_id": "fs-id1344438", "question_text": "What led to the creation of the exurbs?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 2, "ans_text": "They are synonymous with housing projects and urban poor." }, "bloom": null, "hl_context": "Social Policy and Debate Suburbs Are Not All White Picket Fences : The Banlieues of Paris What makes a suburb a suburb ? Simply , a suburb is a community surrounding a city . But when you picture a suburb in your mind , your image may vary widely depending on which nation you call home . <hl> In the United States , most consider the suburbs home to upper and middle class people with private homes . <hl> <hl> In other countries , like France , the suburbs – – or “ banlieues ” – – are synonymous with housing projects and impoverished communities . <hl> <hl> In fact , the banlieues of Paris are notorious for their ethnic violence and crime , with higher unemployment and more residents living in poverty than in the city center . <hl> Further , the banlieues have a much higher immigrant population , which in Paris is mostly Arabic and African immigrants . This contradicts the clichéd American image of a typical white-picket-fence suburb .", "hl_sentences": "In the United States , most consider the suburbs home to upper and middle class people with private homes . In other countries , like France , the suburbs – – or “ banlieues ” – – are synonymous with housing projects and impoverished communities . In fact , the banlieues of Paris are notorious for their ethnic violence and crime , with higher unemployment and more residents living in poverty than in the city center .", "question": { "cloze_format": "The suburbs of Paris are different than those of most U.S. cities because ___.", "normal_format": "How are the suburbs of Paris different than those of most U.S. cities?", "question_choices": [ "They are connected by public transportation.", "There are more industrial and business opportunities there.", "They are synonymous with housing projects and urban poor.", "They are less populated." ], "question_id": "fs-id1509811", "question_text": "How are the suburbs of Paris different than those of most U.S. cities?" }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 1, "ans_text": "Less affluent residents are pushed into less desirable areas." }, "bloom": "1", "hl_context": "As was the case in America , other coronations experienced a growth spurt during the Industrial Era . The development of factories brought people from rural to urban areas , and new technology increased the efficiency of transportation , food production , and food preservation . For example , from the mid - 1670s to the early 1900s , London increased its population from 550,000 to 7 million ( Old Bailey Proceedings Online 2011 ) . The most recent phenomenon shaping urbanization around the world is the development of postindustrial cities whose economic base depends on service and information rather than the manufacturing of industry . The professional , educated class populates the postindustrial city , and they expect convenient access to culturally based entertainment ( libraries , museums , historical downtowns , and the like ) uncluttered by factories and the other features of an industrial city . Global favorites like New York , London , and Tokyo are all examples of postindustrial cities . As cities evolve from industrial to postindustrial , gentrification becomes more common . <hl> The practice of gentrification refers to members of the middle and upper classes entering city areas that have been historically less affluent and renovating properties while the poor urban underclass are forced by resulting price pressures to leave those neighborhoods . <hl> This practice is widespread and the lower class is pushed into increasingly decaying portions of the city .", "hl_sentences": "The practice of gentrification refers to members of the middle and upper classes entering city areas that have been historically less affluent and renovating properties while the poor urban underclass are forced by resulting price pressures to leave those neighborhoods .", "question": { "cloze_format": "Gentrification affect cities because ___.", "normal_format": "How does gentrification affect cities?", "question_choices": [ "They become more crowded.", "Less affluent residents are pushed into less desirable areas.", "Traffic issues, including pollution, become worse.", "All of the above" ], "question_id": "fs-id1704916", "question_text": "How does gentrification affect cities?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 0, "ans_text": "The relationship between humans and their environments" }, "bloom": "1", "hl_context": "<hl> The subfield of environmental sociology studies how humans interact with their environments . <hl> <hl> This field is closely related to human ecology , which focuses on the relationship between people and their built and natural environment . <hl> This is an area that is garnering more attention as extreme weather patterns and policy battles over climate change dominate the news . A key factor of environmental sociology is the concept of carrying capacity , which refers to the maximum amount of life that can be sustained within a given area . While this concept can refer to grazing lands or to rivers , it also can be applied to the earth as a whole . <hl> Human ecology is a functionalist field of study that focuses on the relationship between people and their built and natural physical environments ( Park 1915 ) . <hl> Generally speaking , urban land use and urban population distribution occurs in a predictable pattern once we understand how people relate to their living environment . For example , in the United States , we have a transportation system geared to accommodate individuals and families in the form of interstate highways built for cars . In contrast , most parts of Europe emphasize public transportation such as high-speed rail and commuter lines , as well as walking and bicycling . The challenge for a human ecologist working in American urban planning would be to design landscapes and waterscapes with natural beauty , while also figuring out how to provide for free flowing transport of innumerable vehicles — not to mention parking !", "hl_sentences": "The subfield of environmental sociology studies how humans interact with their environments . This field is closely related to human ecology , which focuses on the relationship between people and their built and natural environment . Human ecology is a functionalist field of study that focuses on the relationship between people and their built and natural physical environments ( Park 1915 ) .", "question": { "cloze_format": "Human ecology theory addresses ___ .", "normal_format": "What does human ecology theory address?", "question_choices": [ "The relationship between humans and their environments", "The way that humans impact technology", "How human population reduces the variety of nonhuman species", "The relationship between humans and other species" ], "question_id": "fs-id1316964", "question_text": "What does human ecology theory address?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 3, "ans_text": "All of the above" }, "bloom": "1", "hl_context": "As the examples above illustrate , the issues of urbanization play significant roles in the study of sociology . <hl> Race , economics , and human behavior intersect in cities . <hl> <hl> Let ’ s look at urbanization through the sociological perspectives of functionalism and conflict theory . <hl> <hl> Functional perspectives on urbanization focus generally on the ecology of the city , while conflict perspective tends to focus on political economy . <hl> <hl> Urbanization is the study of the social , political , and economic relationships in cities , and someone specializing in urban sociology would study those relationships . <hl> <hl> In some ways , cities can be microcosms of universal human behavior , while in others they provide a unique environment that yields their own brand of human behavior . <hl> There is no strict dividing line between rural and urban ; rather , there is a continuum where one bleeds into the other . However , once a geographically concentrated population has reached approximately 100,000 people , it typically behaves like a city regardless of what its designation might be .", "hl_sentences": "Race , economics , and human behavior intersect in cities . Let ’ s look at urbanization through the sociological perspectives of functionalism and conflict theory . Functional perspectives on urbanization focus generally on the ecology of the city , while conflict perspective tends to focus on political economy . Urbanization is the study of the social , political , and economic relationships in cities , and someone specializing in urban sociology would study those relationships . In some ways , cities can be microcosms of universal human behavior , while in others they provide a unique environment that yields their own brand of human behavior .", "question": { "cloze_format": "Urbanization includes the sociological study of ___.", "normal_format": "Urbanization includes the sociological study of what?", "question_choices": [ "Urban economics", "Urban politics", "Urban environments", "All of the above" ], "question_id": "fs-id1487098", "question_text": "Urbanization includes the sociological study of what?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 2, "ans_text": "The common grazing lands in Oxford" }, "bloom": "1", "hl_context": "<hl> Big Picture The Tragedy of the Commons You might have heard the expression “ the tragedy of the commons . ” In 1968 , an article of the same title written by Garrett Hardin describes how a common pasture is ruined by overgrazing . <hl> But Hardin was not the first to notice the phenomenon . <hl> Back in the 1800s , Oxford economist William Forster Lloyd looked at the devastated public grazing commons and the unhealthy cattle subject to such limited grazing , and saw , in essence , that the carrying capacity of the commons had been exceeded . <hl> However , since no one held responsibility for the land ( as it was open to all ) , no one was willing to make sacrifices to improve it . Cattle grazers benefitted from adding more cattle to their herd , but they did not have to take on the responsibility of the destroyed lands that were being damaged by overgrazing . So there was an incentive for them to add more head of cattle , and no incentive for restraint .", "hl_sentences": "Big Picture The Tragedy of the Commons You might have heard the expression “ the tragedy of the commons . ” In 1968 , an article of the same title written by Garrett Hardin describes how a common pasture is ruined by overgrazing . Back in the 1800s , Oxford economist William Forster Lloyd looked at the devastated public grazing commons and the unhealthy cattle subject to such limited grazing , and saw , in essence , that the carrying capacity of the commons had been exceeded .", "question": { "cloze_format": "The “tragedy of the commons” is a reference to ___ .", "normal_format": "The “tragedy of the commons” is a reference to what?", "question_choices": [ "Global warming", "African landowners", "The common grazing lands in Oxford", "The misuse of private space" ], "question_id": "fs-id1886527", "question_text": "The “tragedy of the commons” is a reference to what?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 3, "ans_text": "All of the above" }, "bloom": "3", "hl_context": "<hl> As a consequence of population concentrations , water close to human settlements is frequently polluted with untreated or partially treated human waste ( sewage ) , chemicals , radioactivity , and levels of heat sufficient to create large “ dead zones ” incapable of supporting aquatic life . <hl> <hl> The methods of food production used by many core nations rely on liberal doses of nitrogen and pesticides , which end up back in the water supply . <hl> In some cases , water pollution affects the quality of the aquatic life consumed by water and land animals . As we move along the food chain , the pollutants travel from prey to predator . Since humans consume at all levels of the food chain , we ultimately consume the carcinogens , such as mercury , accumulated through several branches of the food web .", "hl_sentences": "As a consequence of population concentrations , water close to human settlements is frequently polluted with untreated or partially treated human waste ( sewage ) , chemicals , radioactivity , and levels of heat sufficient to create large “ dead zones ” incapable of supporting aquatic life . The methods of food production used by many core nations rely on liberal doses of nitrogen and pesticides , which end up back in the water supply .", "question": { "cloze_format": "A way that human activity impacts the water supply is ___ .", "normal_format": "What are ways that human activity impacts the water supply?", "question_choices": [ "Creating sewage", "Spreading chemicals ", "Increasing radioactivity", "All of the above" ], "question_id": "fs-id1809279", "question_text": "What are ways that human activity impacts the water supply?" }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 0, "ans_text": "The fact that a disproportionate percentage of people of color live in environmentally hazardous areas" }, "bloom": "3", "hl_context": "<hl> Environmental racism refers to the way in which minority group neighborhoods ( populated primarily by people of color and members of low socioeconomic groups ) are burdened with a disproportionate number of hazards , including toxic waste facilities , garbage dumps , and other sources of environmental pollution and foul odors that lower the quality of life . <hl> All around the globe , members of minority groups bear a greater burden of the health problems resulting from higher exposure to waste and pollution . This can occur due to unsafe or unhealthy work conditions where no regulations exist ( or are enforced ) for poor workers , or in neighborhoods that are uncomfortably close to toxic materials .", "hl_sentences": "Environmental racism refers to the way in which minority group neighborhoods ( populated primarily by people of color and members of low socioeconomic groups ) are burdened with a disproportionate number of hazards , including toxic waste facilities , garbage dumps , and other sources of environmental pollution and foul odors that lower the quality of life .", "question": { "cloze_format": "An example of environmental racism is ___ .", "normal_format": "Which is an example of environmental racism?", "question_choices": [ "The fact that a disproportionate percentage of people of color live in environmentally hazardous areas", "Greenpeace protests", "The prevalence of asbestos in formerly “whites only” schools", "Prejudice similar to racism against people with different environmental views than one’s own" ], "question_id": "fs-id1485265", "question_text": "Which is an example of environmental racism?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 3, "ans_text": "Reduction of human population" }, "bloom": "1", "hl_context": "<hl> Dredging certain beaches in an attempt to maintain valuable beachfront property from coastal erosion has resulted in greater storm impact on shorelines , and damage to beach ecosystems ( Turneffe Atoll Trust 2008 ) . <hl> <hl> The results of these dredging projects have damaged reefs , sea grass beds , and shorelines , and can kill off large swaths of marine life . <hl> Ultimately , this damage threatens local fisheries , tourism , and other parts of the local economy .", "hl_sentences": "Dredging certain beaches in an attempt to maintain valuable beachfront property from coastal erosion has resulted in greater storm impact on shorelines , and damage to beach ecosystems ( Turneffe Atoll Trust 2008 ) . The results of these dredging projects have damaged reefs , sea grass beds , and shorelines , and can kill off large swaths of marine life .", "question": { "cloze_format": "___ is not a negative outcome of shoreline dredging.", "normal_format": "What is not a negative outcome of shoreline dredging?", "question_choices": [ "Damaged coral reefs", "Death of marine life", "Ruined sea grass beds", "Reduction of human population" ], "question_id": "fs-id1809432", "question_text": "What is not a negative outcome of shoreline dredging?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 0, "ans_text": "Landfill and incineration" }, "bloom": "1", "hl_context": "<hl> There are two primary means of waste disposal in the U . S . : landfill and incineration . <hl> When it comes to dangerous toxins , neither is a good choice . In the case of more innocuous trash , the synthetic Styrofoam and plastics that many of us use every day do not dissolve in a natural way . Burn them , and they release carcinogens into the air . Their improper ( intentional or not ) incineration adds to air pollution and increases smog . Dump them in landfills , and they do not decompose . As landfill sites fill up , we risk an increase in groundwater contamination .", "hl_sentences": "There are two primary means of waste disposal in the U . S . : landfill and incineration .", "question": { "cloze_format": "The two primary methods of waste disposal are ___.", "normal_format": "What are the two primary methods of waste disposal?", "question_choices": [ "Landfill and incineration", "Incineration and compost", "Decomposition and incineration", "Marine dumping and landfills" ], "question_id": "fs-id1986187", "question_text": "What are the two primary methods of waste disposal?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 1, "ans_text": "Recycled in peripheral nations" }, "bloom": null, "hl_context": "So where do they go ? <hl> Many companies ship their e-waste to developing nations in Africa and Asia to be “ recycled . ” While they are , in some senses , recycled , the result is not exactly clean . <hl> In fact , it is one of the dirtiest jobs around . <hl> Overseas , without the benefit of environmental regulation , e-waste dumps become a kind of boomtown for entrepreneurs willing to sort through endless stacks of broken-down electronics for tiny bits of valuable copper , silver , and other precious metals . <hl> Unfortunately , in their hunt , these workers are exposed to deadly toxins .", "hl_sentences": "Many companies ship their e-waste to developing nations in Africa and Asia to be “ recycled . ” While they are , in some senses , recycled , the result is not exactly clean . Overseas , without the benefit of environmental regulation , e-waste dumps become a kind of boomtown for entrepreneurs willing to sort through endless stacks of broken-down electronics for tiny bits of valuable copper , silver , and other precious metals .", "question": { "cloze_format": "A large percentage of e-waste winds up ___. ", "normal_format": "Where does a large percentage of e-waste wind up?", "question_choices": [ "Incinerators", "Recycled in peripheral nations", "Repurposed into new electronics ", "Dumped into ocean repositories" ], "question_id": "fs-id1833753", "question_text": "Where does a large percentage of e-waste wind up?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 0, "ans_text": "Toxic dumps or other objectionable projects" }, "bloom": "1", "hl_context": "<hl> Why does environmental racism exist ? <hl> The reason is simple . Those with resources can raise awareness , money , and public attention to ensure that their communities are unsullied . This has led to an inequitable distribution of environmental burdens . Another method of keeping this inequity alive is NIMBY protests . NIMBY , or Not in My Back Yard , is the name for a movement of engaged citizens who are mostly protesting something objectionable that will happen to them , rather than its existence at all . <hl> Chemical plants , airports , landfills , and other municipal or corporate projects are often the subject of NIMBY demonstrations . <hl> <hl> And equally often , the NIMBYists win , and the objectionable project is moved closer to those who have fewer resources to fight it . <hl>", "hl_sentences": "Why does environmental racism exist ? Chemical plants , airports , landfills , and other municipal or corporate projects are often the subject of NIMBY demonstrations . And equally often , the NIMBYists win , and the objectionable project is moved closer to those who have fewer resources to fight it .", "question": { "cloze_format": "Municipal projects that often result in environmental racism are ___ .", "normal_format": "What types of municipal projects often result in environmental racism?", "question_choices": [ "Toxic dumps or other objectionable projects", "The location of schools, libraries, and other cultural institutions", "Hospitals and other health and safety sites", "Public transportation options" ], "question_id": "fs-id1418414", "question_text": "What types of municipal projects often result in environmental racism?" }, "references_are_paraphrase": 0 } ]
20
20.1 Demography and Population We recently hit a population milestone of seven billion humans on the earth’s surface. The rapidity with which this happened demonstrated an exponential increase from the time it took to grow from five billion to six billion people. In short, the planet is filling up. How quickly will we go from seven billion to eight billion? How will that population be distributed? Where is population the highest? Where is it slowing down? Where will people live? To explore these questions, we turn to demography , or the study of populations. Three of the most important components affecting the issues above are fertility, mortality, and migration. The fertility rate of a society is a measure noting the number of children born. The fertility number is generally lower than the fecundity number, which measures the potential number of children that could be born to women of childbearing age. Sociologists measure fertility using the crude birthrate (the number of live births per 1,000 people per year). Just as fertility measures childbearing, the mortality rate is a measure of the number of people who die. The crude death rate is a number derived from the number of deaths per 1,000 people per year. When analyzed together, fertility and mortality rates help researchers understand the overall growth occurring in a population. Another key element in studying populations is the movement of people into and out of an area. Migration may take the form of immigration, which describes movement into an area to take up permanent residence, or emigration, which refers to movement out of an area to another place of permanent residence. Migration might be voluntary (as when college students study abroad), involuntary (as when Somalians left the drought and famine-stricken portion of their nation to stay in refugee camps), or forced (as when many Native American tribes were removed from the lands they’d lived in for generations). Population Growth Changing fertility, mortality, and migration rates make up the total population composition , a snapshot of the demographic profile of a population. This number can be measured for societies, nations, world regions, or other groups. The population composition includes the sex ratio (the number of men for every hundred women) as well as the population pyramid (a picture of population distribution by sex and age). Country Population (in millions) Fertility Rate Mortality Rate Sex Ratio Male to Female Afghanistan 29.8 5.4% 17.4% 1.05 Sweden 9.1 1.7% 10.2% 0.98 United States of America 313.2 2.1% 8.4% 0.97 Table 20.1 Varying Fertility and Mortality Rated by Country As the table above illustrates, countries vary greatly in fertility rates and mortality rates—the components that make up a population composition. (Chart courtesy of CIA World Factbook 2011) Comparing these three countries reveals that there are more men than women in Afghanistan, whereas the reverse is true in Sweden and the United States. Afghanistan also has significantly higher fertility and mortality rates than either of the other two countries. Do these statistics surprise you? How do you think the population makeup impacts the political climate and economics of the different countries? Demographic Theories Sociologists have long looked at population issues as central to understanding human interactions. Below we will look at four theories about population that inform sociological thought: Malthusian, zero population growth, cornucopian, and demographic transition theories. Malthusian Theory Thomas Malthus (1766–1834) was an English clergyman who made dire predictions about earth’s ability to sustain its growing population. According to Malthusian theory , three factors would control human population that exceeded the earth’s carrying capacity , or how many people can live in a given area considering the amount of available resources. He identified these factors as war, famine, and disease (Malthus 1798). He termed these “positive checks” because they increased mortality rates, thus keeping the population in check, so to speak. These are countered by “preventative checks,” which also seek to control the population, but by reducing fertility rates; preventive checks include birth control and celibacy. Thinking practically, Malthus saw that people could only produce so much food in a given year, yet the population was increasing at an exponential rate. Eventually, he thought people would run out of food and begin to starve. They would go to war over the increasingly scarce resources, reduce the population to a manageable level, and the cycle would begin anew. Of course, this has not exactly happened. The human population has continued to grow long past Malthus’s predictions. So what happened? Why didn’t we die off? There are three reasons that sociologists suggest we continue to expand the population of our planet. First, technological increases in food production have increased both the amount and quality of calories we can produce per person. Second, human ingenuity has developed new medicine to curtail death through disease. Finally, the development and widespread use of contraception and other forms of family planning have decreased the speed at which our population increases. But what about the future? Some still believe that Malthus was correct and that ample resources to support the earth’s population will soon run out. Zero Population Growth A neo-Malthusian researcher named Paul Ehrlich brought Malthus’s predictions into the 20th century. However, according to Ehrlich, it is the environment, not specifically the food supply, that will play a crucial role in the continued health of planet’s population (Ehrlich 1968). His ideas suggest that the human population is moving rapidly toward complete environmental collapse, as privileged people use up or pollute a number of environmental resources, such as water and air. He advocated for a goal of zero population growth (ZPG), in which the number of people entering a population through birth or immigration is equal to the number of people leaving it via death or emigration. While support for this concept is mixed, it is still considered a possible solution to global overpopulation. Cornucopian Theory Of course, some theories are less focused on the pessimistic hypothesis that the world’s population will meet a detrimental challenge to sustaining itself. Cornucopian theory scoffs at the idea of humans wiping themselves out; it asserts that human ingenuity can resolve any environmental or social issues that develop. As an example, it points to the issue of food supply. If we need more food, the theory contends, agricultural scientists will figure out how to grow it, as they have already been doing for centuries. After all, in this perspective, human ingenuity has been up to the task for thousands of years and there is no reason for that pattern not to continue (Simon 1981). Demographic Transition Theory Whether you believe that we are headed for environmental disaster and the end of human existence as we know it, or you think people will always adapt to changing circumstances, there are clear patterns that can be seen in population growth. Societies develop along a predictable continuum as they evolve from unindustrialized to postindustrial. Demographic transition theory (Caldwell and Caldwell 2006) suggests that future population growth will develop along a predictable four-stage model. In Stage 1, birth, death, and infant mortality rates are all high, while life expectancy is short. An example of this stage is 1800s America. As countries begin to industrialize, they enter Stage 2, where birthrates are higher while infant mortality and the death rates drop. Life expectancy also increases. Afghanistan is currently in this stage. Stage 3 occurs once a society is thoroughly industrialized; birthrates decline, while life expectancy continues to increase. Death rates continue to decrease. Mexico’s population is at this stage. In the final phase, Stage 4, we see the postindustrial era of a society. Birth and death rates are low, people are healthier and live longer, and society enters a phase of population stability. Overall population may even decline. Sweden and the United States are considered Stage 4. Current Population Trends As mentioned earlier, the earth’s population is seven billion. That number might not seem particularly jarring on its own; after all, we all know there are lots of people around. But consider the fact that human population grew very slowly for most of our existence, then doubled in the span of half a century to reach six billion in 1999. And now, just over ten years later, we have added another billion. A look at the graph of projected population indicates that growth is not only going to continue, but it will continue at a rapid rate. The United Nations Population Fund (2008) categorizes nations as high fertility, intermediate fertility, or low fertility. They anticipate the population growth to triple between 2011 and 2100 in high-fertility countries, which are currently concentrated in sub-Saharan Africa. For countries with intermediate fertility rates (the U.S., India, and Mexico all fall into this category), growth is expected to be about 26 percent. And low-fertility countries like China, Australia, and most of Europe will actually see population declines of approximately 20 percent. The graphs below illustrate this trend. It would be impossible to discuss population growth and trends without addressing access to family planning resources and birth control. As the stages of population growth indicate, more industrialized countries see birthrates decline as families limit the number of children they have. Today, many people—over 200 million—still lack access to safe family planning, according to USAID (2010). By their report, this need is growing, with demand projected to increase by 40 percent in the next 15 years. Many social scholars would assert that until women are able to have only the children they want and can care for, the poorest countries will always bear the worst burden of overpopulation. 20.2 Urbanization Urbanization is the study of the social, political, and economic relationships in cities, and someone specializing in urban sociology would study those relationships. In some ways, cities can be microcosms of universal human behavior, while in others they provide a unique environment that yields their own brand of human behavior. There is no strict dividing line between rural and urban; rather, there is a continuum where one bleeds into the other. However, once a geographically concentrated population has reached approximately 100,000 people, it typically behaves like a city regardless of what its designation might be. The Growth of Cities According to sociologist Gideon Sjoberg (1965), there are three prerequisites for the development of a city. First, good environment with fresh water and a favorable climate; second, advanced technology, which will produce a food surplus to support non-farmers; and third, strong social organization to ensure social stability and a stable economy. Most scholars agree that the first cities were developed somewhere in ancient Mesopotamia, though there are disagreements about exactly where. Most early cities were small by today’s standards, and the largest city at the time was most likely Rome, with about 650,000 inhabitants (Chandler and Fox 1974). The factors limiting the size of ancient cities included lack of adequate sewage control, limited food supply, and immigration restrictions. For example, serfs were tied to the land, and transportation was limited and inefficient. Today, the primary influence on cities’ growth is economic forces. Since the recent economic recession has reduced housing prices, researchers are waiting to see what happens to urban migration patterns in response. Urbanization in the United States Urbanization in the United States proceeded rapidly during the Industrial Era. As more and more opportunities for work appeared in factories, workers left farms (and the rural communities that housed them) to move to the cities. From mill towns in Massachusetts to tenements in New York, the industrial era saw an influx of poor workers into America’s cities. At various times throughout the country’s history, certain demographic groups, from recent immigrants to post-Civil War southern Blacks, made their way to urban centers to seek a better life in the city. Upton Sinclair’s The Jungle (1906) offers a snapshot of the rapid change taking place at the time. In the book, Sinclair explored the difficult living conditions and hideous and unsafe working conditions in a Chicago-area meatpacking plant. The book brought the plight of the urban working poor to the front and center of the public’s eye, as well as turning the stomachs of most modern readers with its graphic discussion of food preparation before the advent of government regulation. Sociology in the Real World A Postmillennial Jungle : A Story of Coming of Age in the Bronx In 1906, Upton Sinclair’s book of the harsh life and difficult reality of the urban poor burst onto the scene. Almost 100 years later in 2003, Adrien Nicole LeBlanc wrote Random Family: Love, Drugs, Trouble, and Coming of Age in the Bronx . To write her book, LeBlanc spent 10 years with a family in the Bronx, New York, following their struggles, their daily lives, and the extreme difficulties of their urban existence. Her research methods and resulting work reflect the symbolic interactionist perspective of sociology. Unlike most nonfiction books that focus on urban poverty issues, Random Family is not about social or economic policies, declining teenage pregnancy rates, welfare reform, or any of the other critical issues that matter to this demographic. It is the story of a family, starting with two young women and following them through their relationships with abusive boyfriends, through their first jobs (as heroin packers), and through the births of their many children. LeBlanc does not judge them or offer advice, nor does she take the long view and offer perspective on what confluences of history brought them to this place. Instead, she allows readers to follow these young women on their painful attempt to get to a better place, despite having no idea which way to go. The book is eye-opening and offers a compelling look at today’s urban life in an intimate portrait. The lives LeBlanc portrays are not unusual, nor does the book offer a trite solution. It does offer a personal and up-close view of the people who make up the distressing urban statistics that are part of American society. Suburbs and Exurbs As cities grew more crowded, and often more impoverished and costly, more and more people began to migrate back out of them. But instead of returning to rural small towns (like they’d resided in before moving to the city), these people needed close access to the cities for their jobs. In the 1850s, as the urban population greatly expanded and transportation options improved, suburbs developed. Suburbs are the communities surrounding cities, typically close enough for a daily commute in, but far enough away to allow for more space than city living affords. The bucolic suburban landscape of the early 20th century has largely disappeared due to sprawl. Suburban sprawl contributes to traffic congestion, which in turn contributes to commuting time. And commuting times and distances have continued to increase as new suburbs developed farther and farther from city centers. Simultaneously, this dynamic contributed to an exponential increase in natural resource use, like petroleum, which sequentially increased pollution in the form of carbon emissions. As the suburbs became more crowded and lost their charm, those who could afford it turned to the exurbs , communities that exist outside the ring of suburbs and are typically populated by even wealthier families who want more space and have the resources to lengthen their commute. Together, the suburbs, exurbs, and metropolitan areas all combine to form a metropolis . New York was the first American megalopolis , a huge urban corridor encompassing multiple cities and their surrounding suburbs. These metropolises use vast quantities of natural resources and are a growing part of the U.S. landscape. Social Policy and Debate Suburbs Are Not All White Picket Fences: The Banlieues of Paris What makes a suburb a suburb? Simply, a suburb is a community surrounding a city. But when you picture a suburb in your mind, your image may vary widely depending on which nation you call home. In the United States, most consider the suburbs home to upper and middle class people with private homes. In other countries, like France, the suburbs––or “banlieues”–– are synonymous with housing projects and impoverished communities. In fact, the banlieues of Paris are notorious for their ethnic violence and crime, with higher unemployment and more residents living in poverty than in the city center. Further, the banlieues have a much higher immigrant population, which in Paris is mostly Arabic and African immigrants. This contradicts the clichéd American image of a typical white-picket-fence suburb. In 2005, serious riots broke out in the banlieue of Clichy-sous-Bois after two boys were electrocuted while hiding from the police. They were hiding, it is believed, because they were in the wrong place at the wrong time, near the scene of a break-in, and they were afraid the police would not believe their innocence. Only a few days earlier, interior minister Nicolas Sarkozy (who later became president), gave a speech touting new measures against urban violence and referring to the people of the banlieue as “rabble” (BBC 2005). After the deaths and subsequent riots, Sarkozy reiterated his zero tolerance policy toward violence and sent in more police. Ultimately, the violence spread across more than 30 towns and cities in France. Thousands of cars were burned, many hundred were arrested, and both police and protesters suffered serious injuries. Then-President Jacques Chirac responded by pledging more money for housing programs, jobs programs, and education programs to help the banlieues solve the underlying problems that led to such disastrous unrest. But none of the newly launched programs were effective. President Sarkozy ran on a platform of tough regulations toward young offenders, and in 2007 the country elected him. More riots ensued as a response to his election. In 2010, Sarkozy promised “war without mercy” against the crime in the banlieues (France24 2010). Six years after the Clichy-sous-Bois riot, circumstances are no better for those in the banlieues. As the above feature illustrates, the suburbs also have their share of socio-economic problems. In the U.S., the trend of white flight refers to the migration of economically secure white people from racially mixed urban areas toward the suburbs. This has happened throughout the 20th century—due to causes as diverse as the legal end of racial segregation established by Brown v. Board of Education to the Mariel boatlift of Cubans fleeing Cuba’s Mariel port for Miami. The issue only becomes more complex as time goes on. Current trends include middle-class African-American families following “white flight” patterns out of cities, while affluent whites return to cities that have historically had a black majority. The result is that the issues of race, socio-economics, neighborhoods, and communities remain complicated and challenging. Urbanization around the World As was the case in America, other coronations experienced a growth spurt during the Industrial Era. The development of factories brought people from rural to urban areas, and new technology increased the efficiency of transportation, food production, and food preservation. For example, from the mid-1670s to the early 1900s, London increased its population from 550,000 to 7 million (Old Bailey Proceedings Online 2011). The most recent phenomenon shaping urbanization around the world is the development of postindustrial cities whose economic base depends on service and information rather than the manufacturing of industry. The professional, educated class populates the postindustrial city, and they expect convenient access to culturally based entertainment (libraries, museums, historical downtowns, and the like) uncluttered by factories and the other features of an industrial city. Global favorites like New York, London, and Tokyo are all examples of postindustrial cities. As cities evolve from industrial to postindustrial, gentrification becomes more common. The practice of gentrification refers to members of the middle and upper classes entering city areas that have been historically less affluent and renovating properties while the poor urban underclass are forced by resulting price pressures to leave those neighborhoods. This practice is widespread and the lower class is pushed into increasingly decaying portions of the city. Theoretical Perspectives on Urbanization As the examples above illustrate, the issues of urbanization play significant roles in the study of sociology. Race, economics, and human behavior intersect in cities. Let’s look at urbanization through the sociological perspectives of functionalism and conflict theory. Functional perspectives on urbanization focus generally on the ecology of the city, while conflict perspective tends to focus on political economy. Human ecology is a functionalist field of study that focuses on the relationship between people and their built and natural physical environments (Park 1915). Generally speaking, urban land use and urban population distribution occurs in a predictable pattern once we understand how people relate to their living environment. For example, in the United States, we have a transportation system geared to accommodate individuals and families in the form of interstate highways built for cars. In contrast, most parts of Europe emphasize public transportation such as high-speed rail and commuter lines, as well as walking and bicycling. The challenge for a human ecologist working in American urban planning would be to design landscapes and waterscapes with natural beauty, while also figuring out how to provide for free flowing transport of innumerable vehicles—not to mention parking! The concentric zone model (Burgess 1925) is perhaps the most famous example of human ecology. This model views a city as a series of concentric circular areas, expanding outward from the center of the city, with various “zones” invading (new categories of people and businesses overrun the edges of nearby zones) and succeeding (after invasion, the new inhabitants repurpose the areas they have invaded and push out the previous inhabitants) adjacent zones. In this model, Zone A, in the heart of the city, is the center of the business and cultural district. Zone B, the concentric circle surrounding the city center, is composed of formerly wealthy homes split into cheap apartments for new immigrant populations; this zone also houses small manufacturers, pawn shops, and other marginal businesses. Zone C consists of the homes of the working class and established ethnic enclaves. Zone D consists of wealthy homes, white-collar workers, and shopping centers. Zone E contains the estates of the upper class (exurbs) and the suburbs. In contrast to the functionalist approach, theoretical models in the conflict perspective focus on the way that urban areas change according to specific decisions made by political and economic leaders. These decisions generally benefit the middle and upper classes while exploiting the working and lower classes. For example, sociologists Feagin and Parker (1990) suggested three aspects to understanding how political and economic leaders control urban growth. First, economic and political leaders work alongside each other to affect change in urban growth and decline, determining where money flows and how land use is regulated. Second, exchange value and use value are balanced to favor the middle and upper classes so that, for example, public land in poor neighborhoods may be rezoned for use as industrial land. Finally, urban development is dependent on both structure (groups such as local government) and agency (individuals including businessmen and activists), and these groups engage in a push-pull dynamic that determines where and how land is actually used. For example, NIMBY (Not In My Backyard) movements are more likely to emerge in middle and upper-class neighborhoods, so these groups have more control over the usage of local land. Big Picture The Migration of Mothers For some women, caring for their children is a part of everyday life. For others, caring for other people’s children is a job, and often it is a job that takes them away from their own families and increasingly, their own countries. Feminist sociologists (a branch of the conflict theory perspective) find topics like these rich sources of research for the discipline. A 2001 article by sociologist Arlie Hochschild in American Prospect magazine discusses the global phenomenon of women leaving their own families behind in developing countries in order to come to America to be a nanny for wealthy U.S. families. These women’s own children, left behind, might be looked after by an older sibling, a spouse, or a paid care worker. These workers leave their countries to earn $400 a week as a nanny in the U.S., sending home $40 a week to pay the caregiver for their own children (Hochschild 2001). The Commercialization of Intimate Life is Hochschild’s book on the subject. The statistics are startling. Over half the people immigrating to the United States are women, mostly between the ages of 25 and 34. Many of them find employment as domestic workers, and the demand for this type of care in the U.S. is rising. The number of American women in the workforce rose from 28.8 percent in 1950 to 47 percent in 2010 (Waite 1981; United States Department of Labor 2010). Simultaneously, the number of American families that rely on relatives to care for children is steadily decreasing. So the search for trusted, professional care for their children has become a priority worth paying for. So what is the impact of these “global care chains,” as the article calls them? What does it mean for the children left behind? The American children being cared for? The parents? There are no easy answers to these questions, but it does not mean they should not be asked. Just as a conscientious consumer would pay attention to the company that makes her sneakers or computer, so too do we need to pay attention to who is sacrificing what to care for core nation children. This is not to say it is exploitative to hire a nanny from overseas. Many women come to the United States expressly for the purpose of finding those jobs that enable them to send enough money home to pay for schooling and a better life. They do this in the hopes that, someday, their own children will have better opportunities (Hochschild 2001). 20.3 The Environment and Society The subfield of environmental sociology studies how humans interact with their environments. This field is closely related to human ecology, which focuses on the relationship between people and their built and natural environment. This is an area that is garnering more attention as extreme weather patterns and policy battles over climate change dominate the news. A key factor of environmental sociology is the concept of carrying capacity, which refers to the maximum amount of life that can be sustained within a given area. While this concept can refer to grazing lands or to rivers, it also can be applied to the earth as a whole. Big Picture The Tragedy of the Commons You might have heard the expression “the tragedy of the commons.” In 1968, an article of the same title written by Garrett Hardin describes how a common pasture is ruined by overgrazing. But Hardin was not the first to notice the phenomenon. Back in the 1800s, Oxford economist William Forster Lloyd looked at the devastated public grazing commons and the unhealthy cattle subject to such limited grazing, and saw, in essence, that the carrying capacity of the commons had been exceeded. However, since no one held responsibility for the land (as it was open to all), no one was willing to make sacrifices to improve it. Cattle grazers benefitted from adding more cattle to their herd, but they did not have to take on the responsibility of the destroyed lands that were being damaged by overgrazing. So there was an incentive for them to add more head of cattle, and no incentive for restraint. Satellite photos of Africa taken in the 1970s showed this practice to dramatic effect. The images depicted a dark irregular area over 300 miles around. When seen from above, there was a large fenced area, where plenty of grass was growing. Outside the fence, the ground was bare and devastated. The reason was simple: the fenced land was privately owned by informed farmers who carefully rotated their grazing animals and allowed the fields to lie fallow periodically. Outside the fence was land used by nomads. The nomads, like the herdsmen in 1800s Oxford, increased their heads of cattle without planning for its impact on the greater good. The soil eroded, the plants died, then the cattle died, and, ultimately, some of the people died. How does this affect those of us who don’t need to graze our cattle? Well, like the cows, we all need food, water, and clean air to survive. With the increasing world population and the ever-larger megalopolises with tens of millions of people, the limit of the earth’s carrying capacity is called into question. Whether for cattle or humans, when too many take with too little thought to the rest of the population, the result is usually tragedy. Pollution Pollution describes when contaminants are introduced into an environment (water, air, land) at levels that are damaging. Directly related to carrying capacity, environments can often sustain a limited amount of contaminants without marked change, and water, air, and soil can “heal” themselves to a certain degree. However, once contaminant levels reach a certain point, the results can be catastrophic. Water Look at your watch. Wait 15 seconds. Then another 15. In that time, two children have died from lack of access to clean drinking water. Access to safe water is one of the most basic human needs, and it is woefully out of reach for millions of people on the planet. Many of the major diseases that peripheral countries battle, such as diarrhea, cholera, and typhoid, are caused by contaminated water. Often, young children are unable to go to school because they must instead walk several hours a day just to collect potable water for their family. The situation is only getting more dire as the global population increases. Water is a key resource battleground in the 21st century. As every child learns in school, 70 percent of Earth is made of water. Despite that figure, there is a finite amount of water usable by humans and it is constantly used and reused in a sustainable water cycle. The way that humans use this abundant natural resource, however, renders much of it unsuitable for consumption and unable to sustain life. For instance, it takes two and a half liters of water to produce a single liter of Coca-Cola. The company and its bottlers use close to 300 billion liters of water a year, often in locales that are short of useable water (Blanchard 2007). As a consequence of population concentrations, water close to human settlements is frequently polluted with untreated or partially treated human waste (sewage), chemicals, radioactivity, and levels of heat sufficient to create large “dead zones” incapable of supporting aquatic life. The methods of food production used by many core nations rely on liberal doses of nitrogen and pesticides, which end up back in the water supply. In some cases, water pollution affects the quality of the aquatic life consumed by water and land animals. As we move along the food chain, the pollutants travel from prey to predator. Since humans consume at all levels of the food chain, we ultimately consume the carcinogens, such as mercury, accumulated through several branches of the food web. Soil Some of you might have read The Grapes of Wrath in English class years ago. Steinbeck’s tale of the Joads, driven out of their home by the Dust Bowl, is still playing out today. In China, as in Depression-era Oklahoma, over-tilling soil in an attempt to expand agriculture has resulted in the disappearance of large patches of topsoil. Soil erosion and desertification are just two of the many forms of soil pollution. In addition, all of the chemicals and pollutants that harm our water supplies can also leach into soil with similar effects. Brown zones where nothing can grow are common results of soil pollution. One demand of the population boom on the planet is an attendant requirement for more food to be produced. The so-called “Green Revolution” in the 1960s saw chemists and world aid organizations working together to bring modern farming methods, complete with pesticides, to developing countries. The immediate result was positive: food yields went up and burgeoning populations were fed. But as time has gone on, these areas have fallen into even more difficult straits as the damage done by modern methods leave traditional farmers with less than they had to start. Dredging certain beaches in an attempt to maintain valuable beachfront property from coastal erosion has resulted in greater storm impact on shorelines, and damage to beach ecosystems (Turneffe Atoll Trust 2008). The results of these dredging projects have damaged reefs, sea grass beds, and shorelines, and can kill off large swaths of marine life. Ultimately, this damage threatens local fisheries, tourism, and other parts of the local economy. Garbage Where is your last cell phone? What about the one before that? Or the huge old television set your family had before flat screens became popular? For most of us, the answer is a sheepish shrug. We don’t pay attention to the demise of old items, and since electronics drop in price and increase in innovation at an incredible clip, we have been trained by their manufacturers to upgrade frequently. Garbage creation and control are major issues for most core and industrializing nations, quickly becoming one of the most critical environmental issues faced in America. Americans buy products, use them, and then throw them away. When you got rid of those old electronics, where did they go? Did you dispose of them according to government safety guidelines? Chances are good you didn’t even know there are guidelines. Multiply your electronics times a few million, take into account the numerous toxic chemicals they contain, and then imagine either burying those chemicals in the ground, or lighting them on fire. There are two primary means of waste disposal in the U.S.: landfill and incineration. When it comes to dangerous toxins, neither is a good choice. In the case of more innocuous trash, the synthetic Styrofoam and plastics that many of us use every day do not dissolve in a natural way. Burn them, and they release carcinogens into the air. Their improper (intentional or not) incineration adds to air pollution and increases smog. Dump them in landfills, and they do not decompose. As landfill sites fill up, we risk an increase in groundwater contamination. What Should Apple (and Friends) Do about E-Waste? Electronic waste, or e-waste, is one of the fastest growing segments of garbage. And it is far more problematic than even the mountains of broken plastic and rusty metal that plague the environment. E-waste is the name for obsolete, broken, and worn-out electronics—from computers to mobile phones to televisions. The challenge is that these products, which are multiplying at alarming rates thanks in part to planned obsolescence (designing products to quickly become outdated and then replaced by the constant emergence of newer and cheaper electronics), have toxic chemicals and precious metals in them, which makes for a dangerous combination. So where do they go? Many companies ship their e-waste to developing nations in Africa and Asia to be “recycled.” While they are, in some senses, recycled, the result is not exactly clean. In fact, it is one of the dirtiest jobs around. Overseas, without the benefit of environmental regulation, e-waste dumps become a kind of boomtown for entrepreneurs willing to sort through endless stacks of broken-down electronics for tiny bits of valuable copper, silver, and other precious metals. Unfortunately, in their hunt, these workers are exposed to deadly toxins. Governments are beginning to take notice of the impending disaster, and the European Union, as well as the state of California, has put stricter regulations in place. These regulations both limit the amount of toxins allowed in electronics and address the issue of end-of-life recycling. But not surprisingly, corporations, while insisting they are greening their process, often fight stricter regulations. Meanwhile, many environmental groups, including the activist group Greenpeace, have taken up the cause. Greenpeace states that it is working to get companies to: measure and reduce emissions with energy efficiency, renewable energy, and energy policy advocacy make greener, efficient, longer lasting products that are free of hazardous substance reduce environmental impacts throughout company operations, from materials and energy used to make products right through to global take-back programs for old products (Greenpeace 2011). Greenpeace produces annual ratings of how well companies are meeting these goals so that consumers can see how brands stack up. For instance, Apple moved up five spots since the 2010 report. Hopefully, consumers will vote with their wallets, and the greener companies will be rewarded. Air China’s fast-growing economy and burgeoning industry have translated into notoriously poor air quality. Smog hangs heavily over the major cities, sometimes grounding aircraft that cannot navigate through it. Pedestrians and cyclists wear masks to protect themselves. In Beijing, citizens are skeptical that the government-issued daily pollution ratings are trustworthy. Increasingly, they are taking their own pollution measurements in the hopes that accurate information will galvanize others to action. Given that some days they can barely see down the street, they hope that action comes soon (Papenfuss 2011). Humanity, with its growing population, use of fossil fuels, and increasingly urbanized society, is putting too much stress on the earth’s atmosphere. The amount of air pollution varies from locale to locale, and you may be more personally affected than you realize. How often do you check air quality reports before leaving your house? Depending on where you live, this question can sound utterly strange or like an everyday matter. Along with oxygen, most of the time we are also breathing in soot, hydrocarbons, carbon, nitrogen, and sulfur oxides. As discussed above, in some parts of the world, it is a necessity for people to check air quality levels, and it is not uncommon to wear air filters on particularly bad days. Much of the pollution in the air comes from human activity. How many college students move their cars across campus at least once a day? Who checks the environmental report card on how many pollutants each company throws into the air before purchasing a cell phone? Many of us are guilty of taking our environment for granted without concern for how everyday decisions add up to a long-term global problem. How many minor adjustments can you think of, like walking instead of driving, that would reduce your overall carbon footprint? Remember the example of the “tragedy of the commons.” Each of us is affected by air pollution. But like the herder who adds one more head of cattle to realize the benefits of owning more cows, but who does not have to pay the price of the overgrazed land, we take the benefit of driving or buying the latest cell phones without worrying about the end result. Air pollution accumulates in the body, much like the effects of smoking cigarettes accumulate over time, leading to more chronic illnesses. And in addition to directly affecting human health, air pollution affects crop quality as well as heating and cooling costs. In other words, we all pay a lot more than the price at the pump when we fill up our tank with gas. Toxic and Radioactive Waste Radioactivity is a form of air pollution. While nuclear energy promises a safe and abundant power source, increasingly it is looked upon as a danger to the environment and to those who inhabit it. We accumulate nuclear waste, which we must then keep track of long term and ultimately figure out how to store the toxic waste material without damaging the environment or putting future generations at risk. The recent earthquake in Japan illustrates the dangers of even safe, government-monitored nuclear energy. When disaster occurs, how can we safely evacuate the large numbers of affected people? Indeed, how can we even be sure how far the evacuation radius should extend? Radiation can also enter the food chain, causing damage from the bottom (phytoplankton and microscopic soil organisms) all the way to the top. Once again, the price paid for cheap power is much greater than what is seen on the electric bill. The enormous oil disaster that hit the Louisiana Gulf Coast is just one of a frighteningly high number of environmental crises that have led to toxic residue. From the Love Canal neighborhood of the 1970s to the Exxon Valdez oil tanker crash of 1989, from the Chernobyl disaster of 1986 to Japan’s Fukushima nuclear plant incident in 2011—the list goes on. Often, the stories are not newsmakers, but simply an unpleasant part of life for the people who live near toxic sites such as in the stories of Centralia, Pennsylvania and Hinkley, California. In many cases, people in these neighborhoods can be part of a cancer cluster without realizing the cause. Climate Change World systems analysis suggests that core nations (like the U.S. and Western Europe) were historically the greatest source of greenhouse gases, but have now evolved into postindustrial societies. Now that semi-peripheral and peripheral nations are industrializing, the core nations wish to enact strict protocols regarding the causes of global warming (since their economies are no longer so dependent on greenhouse-gas-causing industries). However, the semi-peripheral and peripheral nations rightly point out that they only want the same economic chance to evolve their economies, and since they were unduly affected by the progress of core nations, if the core nations now insist on “green” policies, they should pay offsets or subsidies of some kind. There are no easy answers to this conflict. It may well not be “fair” that the core nations benefited from ignorance during their industrial boom. But with China leading the way as a top greenhouse gas emitter, it matters less to the planet whether they get their fair shake at polluting. The international community continues to work toward a way to manage climate change. The Durban Talks that concluded in December 2011 point to a willingness by both core countries and peripheral nations to move toward a legally binding instrument for all countries (World Resource Institute 2011). Climate change, which used to be called global warming, is a deeply controversial subject, despite decades of scientific research that demonstrates its existence. Climate change refers to long-term shifts in temperatures due to human activity and, in particular, the release of greenhouse gases into the environment. While the planet as a whole is warming––hence the term global warming––the term climate change is now used because the short-term variations can include higher or lower temperatures, despite the overarching trend toward warmth. Another effect is more extreme weather. There are increasingly more record-breaking weather phenomena, from the number of Category 4 hurricanes to the amount of snowfall in a given winter. These extremes, while they make for dramatic television coverage, can cause immeasurable damage to crops, property, and even lives. So why is climate change a controversy? The National Oceanographic and Atmospheric Association (NOAA) recognizes its existence. So do the close to 200 countries that signed the Kyoto Protocol, a document intended to engage countries in voluntary actions to limit the activity that leads to climate change. (The United States was not one of the 200 nations committed to this initiative to reduce environmental damage, and the refusal to sign continues to be a source of contention.) So what’s the argument about? Well, for the companies making billions of dollars in the production of goods and services, climate change is a dirty concept indeed. The idea of costly regulations that would require expensive operational upgrades has been a source of great anxiety to much of the business community, and as a rebuttal they argue, via lobbyists, that such regulations would be disastrous for the economy. Some go so far as to question the science used as evidence. There is a lot of finger-pointing among countries, especially when the issue arises of who “gets” to pollute. Sociology in the Real World Would You Buy an Environmental Cause from This Woman? From breakfast cereals to sports cars, we are used to seeing our favorite actors touting products of all kinds. But what about environmental causes? Who is more trustworthy when it comes to promoting the health of our planet: former vice-president Al Gore or international superstar Angelina Jolie? According to a report by Nielsen and the Environmental Change Institute, the answer may vary depending on what country you’re in. Globally, Kofi Annan and Al Gore won top spots as trustworthy spokespeople, but among respondents under age 25, Oprah Winfrey and Angelina Jolie joined Kofi as the most influential spokespeople. And regionally, results varied, with some countries preferring rock stars while others liked getting their environmental messages from sports heroes (Nielsen 2007). Why do we trust the message when it comes from these sources? Most of us don’t think that these famous people are scientists in their own right, so it is unclear why their word regarding climate change is so valuable. But it clearly is. Many environmental nonprofits have connected with a celebrity to help them raise money and awareness. But before you write a check to Angelina Jolie’s favorite charity or support Bono’s most recent project, it is important to look behind the celebrity, and at the organizations themselves. Environmental Racism Environmental racism refers to the way in which minority group neighborhoods (populated primarily by people of color and members of low socioeconomic groups) are burdened with a disproportionate number of hazards, including toxic waste facilities, garbage dumps, and other sources of environmental pollution and foul odors that lower the quality of life. All around the globe, members of minority groups bear a greater burden of the health problems resulting from higher exposure to waste and pollution. This can occur due to unsafe or unhealthy work conditions where no regulations exist (or are enforced) for poor workers, or in neighborhoods that are uncomfortably close to toxic materials. The statistics on environmental racism are shocking. When studying the impact on African Americans, research shows that it pervades all aspects of their lives: environmentally unsound housing, schools with asbestos problems, facilities and playgrounds with lead paint. A 20-year comparative study led by sociologist Robert Bullard determined “race to be more important than socioeconomic status in predicting the location of the nation’s commercial hazardous waste facilities” (Bullard et al. 2007). His research found, for example, that African American children are five times more likely to have lead poisoning (the leading environmental health threat for children) than their Caucasian counterparts, and that a disproportionate number of people of color reside in areas with hazardous waste facilities (Bullard et al. 2007). Sociologists involved with the project are examining how environmental racism is addressed in the long-term cleanup of the environmental disasters caused by Hurricane Katrina. Big Picture American Indian Tribes and Environmental Racism Native Americans are unquestionably victims of environmental racism. The Commission for Racial Justice found that about 50 percent of all American Indians live in communities with uncontrolled hazardous waste sites (Asian Pacific Environmental Network 2002). There’s no question that, worldwide, indigenous populations are suffering from similar fates. For Native American tribes, the issues can be complicated—and their solutions hard to attain—because of the complicated governmental issues arising from a history of institutionalized disenfranchisement. Unlike other racial minorities in the U.S., Native American tribes are sovereign nations. However, much of their land is held in “trust,” meaning that “the federal government holds title to the land in trust on behalf of the tribe” (Bureau of Indian Affairs 2012). Some instances of environmental damage arise from this crossover, where the U.S. government’s title has meant it acts without approval of the tribal government. Other significant contributors to environmental racism as experienced by tribes are forcible removal and preposterous red tape to receive the same reparation benefits afforded to non-Indians. To better understand how this happens, let’s consider a few example cases. The Skull Valley Band of Goshute Indians was targeted as the site for a high-level nuclear waste dumping ground, amid allegations of a payoff of as high as $200 million (Kamps 2001). Keith Lewis, an indigenous advocate for Indian rights, commented on this buyout, after his people endured decades of uranium contamination, saying that “there is nothing moral about tempting a starving man with money” (Kamps 2001). In another example, the Western Shoshone’s Yucca Mountain area has been pursued by mining companies for its rich uranium stores, a threat that adds to the existing radiation exposure this area suffers from U.S. and British nuclear bomb testing (Environmental Justice Case Studies 2004). In the “four corners” area where Colorado, Utah, Arizona, and New Mexico meet, a group of Hopi and Navajo families have been forcibly removed from their homes so the land could be mined by the Peabody Mining Company for coal valued at $10 billion (American Indian Cultural Support 2006). Years of uranium mining on the lands of the Navajo of New Mexico have led to serious health consequences, and reparations have been difficult to secure; in addition to the loss of life, people’s homes and other facilities have been contaminated (Frosch 2009). In yet another case, members of the Chippewa near White Pine, Michigan, were unable to stop the transport of hazardous sulfuric acid across reservation lands, but their activism helped bring an end to the mining project that used the acid (Environmental Justice Case Studies 2004). These examples are only a few of the hundreds of incidents that American Indian tribes have faced and continue to battle against. Sadly, the mistreatment of the land’s original inhabitants continues via this institution of environmental racism. How might the work of sociologists help draw attention to—and eventually mitigate—this social problem? Why does environmental racism exist? The reason is simple. Those with resources can raise awareness, money, and public attention to ensure that their communities are unsullied. This has led to an inequitable distribution of environmental burdens. Another method of keeping this inequity alive is NIMBY protests. NIMBY , or Not in My Back Yard, is the name for a movement of engaged citizens who are mostly protesting something objectionable that will happen to them, rather than its existence at all. Chemical plants, airports, landfills, and other municipal or corporate projects are often the subject of NIMBY demonstrations. And equally often, the NIMBYists win, and the objectionable project is moved closer to those who have fewer resources to fight it.
biology
Chapter Outline 18.1 Understanding Evolution 18.2 Formation of New Species 18.3 Reconnection and Rates of Speciation Introduction All species of living organisms, from bacteria to baboons to blueberries, evolved at some point from a different species. Although it may seem that living things today stay much the same, that is not the case—evolution is an ongoing process. The theory of evolution is the unifying theory of biology, meaning it is the framework within which biologists ask questions about the living world. Its power is that it provides direction for predictions about living things that are borne out in experiment after experiment. The Ukrainian-born American geneticist Theodosius Dobzhansky famously wrote that “nothing makes sense in biology except in the light of evolution.” 1 He meant that the tenet that all life has evolved and diversified from a common ancestor is the foundation from which we approach all questions in biology. 1 Theodosius Dobzhansky. “Biology, Molecular and Organismic.” American Zoologist 4, no. 4 (1964): 449.
[ { "answer": { "ans_choice": 1, "ans_text": "natural selection" }, "bloom": "1", "hl_context": "<hl> Wallace and Darwin both observed similar patterns in other organisms and they independently developed the same explanation for how and why such changes could take place . <hl> <hl> Darwin called this mechanism natural selection . <hl> Natural selection , also known as “ survival of the fittest , ” is the more prolific reproduction of individuals with favorable traits that survive environmental change because of those traits ; this leads to evolutionary change .", "hl_sentences": "Wallace and Darwin both observed similar patterns in other organisms and they independently developed the same explanation for how and why such changes could take place . Darwin called this mechanism natural selection .", "question": { "cloze_format": "The scientific concept that Charles Darwin and Alfred Wallace independently discovered is ___.", "normal_format": "Which scientific concept did Charles Darwin and Alfred Wallace independently discover?", "question_choices": [ "mutation", "natural selection", "overbreeding", "sexual reproduction" ], "question_id": "fs-idp17417072", "question_text": "Which scientific concept did Charles Darwin and Alfred Wallace independently discover?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 3, "ans_text": "all of the above" }, "bloom": null, "hl_context": "Natural selection , Darwin argued , was an inevitable outcome of three principles that operated in nature . First , most characteristics of organisms are inherited , or passed from parent to offspring . Although no one , including Darwin and Wallace , knew how this happened at the time , it was a common understanding . <hl> Second , more offspring are produced than are able to survive , so resources for survival and reproduction are limited . <hl> The capacity for reproduction in all organisms outstrips the availability of resources to support their numbers . Thus , there is competition for those resources in each generation . Both Darwin and Wallace ’ s understanding of this principle came from reading an essay by the economist Thomas Malthus who discussed this principle in relation to human populations . <hl> Third , offspring vary among each other in regard to their characteristics and those variations are inherited . <hl> Darwin and Wallace reasoned that offspring with inherited characteristics which allow them to best compete for limited resources will survive and have more offspring than those individuals with variations that are less able to compete . Because characteristics are inherited , these traits will be better represented in the next generation . This will lead to change in populations over generations in a process that Darwin called descent with modification . <hl> Ultimately , natural selection leads to greater adaptation of the population to its local environment ; it is the only mechanism known for adaptive evolution . <hl> Wallace and Darwin both observed similar patterns in other organisms and they independently developed the same explanation for how and why such changes could take place . Darwin called this mechanism natural selection . <hl> Natural selection , also known as “ survival of the fittest , ” is the more prolific reproduction of individuals with favorable traits that survive environmental change because of those traits ; this leads to evolutionary change . <hl>", "hl_sentences": "Second , more offspring are produced than are able to survive , so resources for survival and reproduction are limited . Third , offspring vary among each other in regard to their characteristics and those variations are inherited . Ultimately , natural selection leads to greater adaptation of the population to its local environment ; it is the only mechanism known for adaptive evolution . Natural selection , also known as “ survival of the fittest , ” is the more prolific reproduction of individuals with favorable traits that survive environmental change because of those traits ; this leads to evolutionary change .", "question": { "cloze_format": "The situation that will lead to natural selection is ___.", "normal_format": "Which of the following situations will lead to natural selection?", "question_choices": [ "The seeds of two plants land near each other and one grows larger than the other.", "Two types of fish eat the same kind of food, and one is better able to gather food than the other.", "Male lions compete for the right to mate with females, with only one possible winner.", "all of the above" ], "question_id": "fs-idp75629984", "question_text": "Which of the following situations will lead to natural selection?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 3, "ans_text": "all of the above" }, "bloom": "2", "hl_context": "The evolution of species has resulted in enormous variation in form and function . Sometimes , evolution gives rise to groups of organisms that become tremendously different from each other . <hl> When two species evolve in diverse directions from a common point , it is called divergent evolution . <hl> Such divergent evolution can be seen in the forms of the reproductive organs of flowering plants which share the same basic anatomies ; however , they can look very different as a result of selection in different physical environments and adaptation to different kinds of pollinators ( Figure 18.5 ) . <hl> In other cases , similar phenotypes evolve independently in distantly related species . <hl> <hl> For example , flight has evolved in both bats and insects , and they both have structures we refer to as wings , which are adaptations to flight . <hl> <hl> However , the wings of bats and insects have evolved from very different original structures . <hl> <hl> This phenomenon is called convergent evolution , where similar traits evolve independently in species that do not share a common ancestry . <hl> <hl> The two species came to the same function , flying , but did so separately from each other . <hl> These physical changes occur over enormous spans of time and help explain how evolution occurs . Natural selection acts on individual organisms , which in turn can shape an entire species . Although natural selection may work in a single generation on an individual , it can take thousands or even millions of years for the genotype of an entire species to evolve . It is over these large time spans that life on earth has changed and continues to change .", "hl_sentences": "When two species evolve in diverse directions from a common point , it is called divergent evolution . In other cases , similar phenotypes evolve independently in distantly related species . For example , flight has evolved in both bats and insects , and they both have structures we refer to as wings , which are adaptations to flight . However , the wings of bats and insects have evolved from very different original structures . This phenomenon is called convergent evolution , where similar traits evolve independently in species that do not share a common ancestry . The two species came to the same function , flying , but did so separately from each other .", "question": { "cloze_format": "The situation that is most likely an example of convergent evolution is ___.", "normal_format": "Which situation is most likely an example of convergent evolution?", "question_choices": [ "Squid and humans have eyes similar in structure.", "Worms and snakes both move without legs.", "Some bats and birds have wings that allow them to fly", "all of the above" ], "question_id": "fs-idp75619248", "question_text": "Which situation is most likely an example of convergent evolution?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 0, "ans_text": " flood causes the formation of a new lake." }, "bloom": "2", "hl_context": "<hl> Isolation of populations leading to allopatric speciation can occur in a variety of ways : a river forming a new branch , erosion forming a new valley , a group of organisms traveling to a new location without the ability to return , or seeds floating over the ocean to an island . <hl> The nature of the geographic separation necessary to isolate populations depends entirely on the biology of the organism and its potential for dispersal . If two flying insect populations took up residence in separate nearby valleys , chances are , individuals from each population would fly back and forth continuing gene flow . <hl> However , if two rodent populations became divided by the formation of a new lake , continued gene flow would be unlikely ; therefore , speciation would be more likely . <hl>", "hl_sentences": "Isolation of populations leading to allopatric speciation can occur in a variety of ways : a river forming a new branch , erosion forming a new valley , a group of organisms traveling to a new location without the ability to return , or seeds floating over the ocean to an island . However , if two rodent populations became divided by the formation of a new lake , continued gene flow would be unlikely ; therefore , speciation would be more likely .", "question": { "cloze_format": "The situation that would most likely lead to allopatric speciation is ___.", "normal_format": "Which situation would most likely lead to allopatric speciation?", "question_choices": [ " flood causes the formation of a new lake.", "A storm causes several large trees to fall down.", "A mutation causes a new trait to develop.", "An injury causes an organism to seek out a new food source." ], "question_id": "fs-idm19556240", "question_text": "Which situation would most likely lead to allopatric speciation?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 1, "ans_text": "One involves the movement of the organism, and the other involves a change in the environment." }, "bloom": null, "hl_context": "<hl> Biologists group allopatric processes into two categories : dispersal and vicariance . <hl> <hl> Dispersal is when a few members of a species move to a new geographical area , and vicariance is when a natural situation arises to physically divide organisms . <hl>", "hl_sentences": "Biologists group allopatric processes into two categories : dispersal and vicariance . Dispersal is when a few members of a species move to a new geographical area , and vicariance is when a natural situation arises to physically divide organisms .", "question": { "cloze_format": "The main difference between dispersal and vicariance is that ___.", "normal_format": "What is the main difference between dispersal and vicariance?", "question_choices": [ "One leads to allopatric speciation, whereas the other leads to sympatric speciation.", "One involves the movement of the organism, and the other involves a change in the environment.", "One depends on a genetic mutation occurring, and the other does not.", "One involves closely related organisms, and the other involves only individuals of the same species." ], "question_id": "fs-idm147867984", "question_text": "What is the main difference between dispersal and vicariance?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 1, "ans_text": "longer distance between divided groups" }, "bloom": "2", "hl_context": "<hl> Additionally , scientists have found that the further the distance between two groups that once were the same species , the more likely it is that speciation will occur . <hl> <hl> This seems logical because as the distance increases , the various environmental factors would likely have less in common than locations in close proximity . <hl> Consider the two owls : in the north , the climate is cooler than in the south ; the types of organisms in each ecosystem differ , as do their behaviors and habits ; also , the hunting habits and prey choices of the southern owls vary from the northern owls . These variances can lead to evolved differences in the owls , and speciation likely will occur . <hl> Allopatric Speciation <hl>", "hl_sentences": "Additionally , scientists have found that the further the distance between two groups that once were the same species , the more likely it is that speciation will occur . This seems logical because as the distance increases , the various environmental factors would likely have less in common than locations in close proximity . Allopatric Speciation", "question": { "cloze_format": "The variable that increases the likelihood of allopatric speciation taking place more quickly is ___ .", "normal_format": "Which variable increases the likelihood of allopatric speciation taking place more quickly?", "question_choices": [ "lower rate of mutation", "longer distance between divided groups", "increased instances of hybrid formation", "equivalent numbers of individuals in each population" ], "question_id": "fs-idp21033648", "question_text": "Which variable increases the likelihood of allopatric speciation taking place more quickly?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 2, "ans_text": "the source of the extra chromosomes" }, "bloom": null, "hl_context": "<hl> Polyploidy is a condition in which a cell or organism has an extra set , or sets , of chromosomes . <hl> Scientists have identified two main types of polyploidy that can lead to reproductive isolation of an individual in the polyploidy state . Reproductive isolation is the inability to interbreed . <hl> In some cases , a polyploid individual will have two or more complete sets of chromosomes from its own species in a condition called autopolyploidy ( Figure 18.15 ) . <hl> <hl> The prefix “ auto - ” means “ self , ” so the term means multiple chromosomes from one ’ s own species . <hl> Polyploidy results from an error in meiosis in which all of the chromosomes move into one cell instead of separating .", "hl_sentences": "Polyploidy is a condition in which a cell or organism has an extra set , or sets , of chromosomes . In some cases , a polyploid individual will have two or more complete sets of chromosomes from its own species in a condition called autopolyploidy ( Figure 18.15 ) . The prefix “ auto - ” means “ self , ” so the term means multiple chromosomes from one ’ s own species .", "question": { "cloze_format": "The main difference between autopolyploid and allopolyploid is ___ .", "normal_format": "What is the main difference between autopolyploid and allopolyploid?", "question_choices": [ "the number of chromosomes", "the functionality of the chromosomes", "the source of the extra chromosomes", "the number of mutations in the extra chromosomes" ], "question_id": "fs-idm124500272", "question_text": "What is the main difference between autopolyploid and allopolyploid?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 2, "ans_text": "when members of closely related species reproduce" }, "bloom": null, "hl_context": "After speciation , two species may recombine or even continue interacting indefinitely . Individual organisms will mate with any nearby individual who they are capable of breeding with . <hl> An area where two closely related species continue to interact and reproduce , forming hybrids , is called a hybrid zone . <hl> <hl> Over time , the hybrid zone may change depending on the fitness of the hybrids and the reproductive barriers ( Figure 18.22 ) . <hl> If the hybrids are less fit than the parents , reinforcement of speciation occurs , and the species continue to diverge until they can no longer mate and produce viable offspring . If reproductive barriers weaken , fusion occurs and the two species become one . Barriers remain the same if hybrids are fit and reproductive : stability may occur and hybridization continues .", "hl_sentences": "An area where two closely related species continue to interact and reproduce , forming hybrids , is called a hybrid zone . Over time , the hybrid zone may change depending on the fitness of the hybrids and the reproductive barriers ( Figure 18.22 ) .", "question": { "cloze_format": "The reproductive combination that produces hybrids is ___.", "normal_format": "Which reproductive combination produces hybrids?", "question_choices": [ "when individuals of the same species in different geographical areas reproduce", "when any two individuals sharing the same habitat reproduce", "when members of closely related species reproduce", "when offspring of the same parents reproduce" ], "question_id": "fs-idm37813424", "question_text": "Which reproductive combination produces hybrids?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 2, "ans_text": "It does not exchange genetic information with other species." }, "bloom": null, "hl_context": "Some types of prezygotic barriers prevent reproduction entirely . Many organisms only reproduce at certain times of the year , often just annually . <hl> Differences in breeding schedules , called temporal isolation , can act as a form of reproductive isolation . <hl> For example , two species of frogs inhabit the same area , but one reproduces from January to March , whereas the other reproduces from March to May ( Figure 18.17 ) . In some cases , populations of a species move or are moved to a new habitat and take up residence in a place that no longer overlaps with the other populations of the same species . This situation is called habitat isolation . <hl> Reproduction with the parent species ceases , and a new group exists that is now reproductively and genetically independent . <hl> For example , a cricket population that was divided after a flood could no longer interact with each other . Over time , the forces of natural selection , mutation , and genetic drift will likely result in the divergence of the two groups ( Figure 18.18 ) . Behavioral isolation occurs when the presence or absence of a specific behavior prevents reproduction from taking place . For example , male fireflies use specific light patterns to attract females . Various species of fireflies display their lights differently . If a male of one species tried to attract the female of another , she would not recognize the light pattern and would not mate with the male .", "hl_sentences": "Differences in breeding schedules , called temporal isolation , can act as a form of reproductive isolation . Reproduction with the parent species ceases , and a new group exists that is now reproductively and genetically independent .", "question": { "cloze_format": "The condition that is the basis for a species to be reproductively isolated from other members is that ___.", "normal_format": "Which condition is the basis for a species to be reproductively isolated from other members?", "question_choices": [ "It does not share its habitat with related species.", "It does not exist out of a single habitat.", "It does not exchange genetic information with other species.", "It does not undergo evolutionary changes for a significant period of time." ], "question_id": "fs-idm23518704", "question_text": "Which condition is the basis for a species to be reproductively isolated from other members?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 3, "ans_text": "Two species of insects produce infertile offspring." }, "bloom": null, "hl_context": "<hl> Some types of prezygotic barriers prevent reproduction entirely . <hl> <hl> Many organisms only reproduce at certain times of the year , often just annually . <hl> <hl> Differences in breeding schedules , called temporal isolation , can act as a form of reproductive isolation . <hl> <hl> For example , two species of frogs inhabit the same area , but one reproduces from January to March , whereas the other reproduces from March to May ( Figure 18.17 ) . <hl> <hl> In some cases , populations of a species move or are moved to a new habitat and take up residence in a place that no longer overlaps with the other populations of the same species . <hl> <hl> This situation is called habitat isolation . <hl> Reproduction with the parent species ceases , and a new group exists that is now reproductively and genetically independent . For example , a cricket population that was divided after a flood could no longer interact with each other . Over time , the forces of natural selection , mutation , and genetic drift will likely result in the divergence of the two groups ( Figure 18.18 ) . Behavioral isolation occurs when the presence or absence of a specific behavior prevents reproduction from taking place . For example , male fireflies use specific light patterns to attract females . Various species of fireflies display their lights differently . If a male of one species tried to attract the female of another , she would not recognize the light pattern and would not mate with the male .", "hl_sentences": "Some types of prezygotic barriers prevent reproduction entirely . Many organisms only reproduce at certain times of the year , often just annually . Differences in breeding schedules , called temporal isolation , can act as a form of reproductive isolation . For example , two species of frogs inhabit the same area , but one reproduces from January to March , whereas the other reproduces from March to May ( Figure 18.17 ) . In some cases , populations of a species move or are moved to a new habitat and take up residence in a place that no longer overlaps with the other populations of the same species . This situation is called habitat isolation .", "question": { "cloze_format": "___ is a situation that is not an example of a prezygotic barrier.", "normal_format": "Which situation is not an example of a prezygotic barrier?", "question_choices": [ "Two species of turtles breed at different times of the year.", "Two species of flowers attract different pollinators.", "Two species of birds display different mating dances.", "Two species of insects produce infertile offspring." ], "question_id": "fs-idp102553968", "question_text": "Which situation is not an example of a prezygotic barrier?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 0, "ans_text": "reinforcement" }, "bloom": null, "hl_context": "<hl> Hybrids can be either less fit than the parents , more fit , or about the same . <hl> <hl> Usually hybrids tend to be less fit ; therefore , such reproduction diminishes over time , nudging the two species to diverge further in a process called reinforcement . <hl> <hl> This term is used because the low success of the hybrids reinforces the original speciation . <hl> <hl> If the hybrids are as fit or more fit than the parents , the two species may fuse back into one species ( Figure 18.23 ) . <hl> Scientists have also observed that sometimes two species will remain separate but also continue to interact to produce some hybrid individuals ; this is classified as stability because no real net change is taking place . After speciation , two species may recombine or even continue interacting indefinitely . Individual organisms will mate with any nearby individual who they are capable of breeding with . An area where two closely related species continue to interact and reproduce , forming hybrids , is called a hybrid zone . Over time , the hybrid zone may change depending on the fitness of the hybrids and the reproductive barriers ( Figure 18.22 ) . <hl> If the hybrids are less fit than the parents , reinforcement of speciation occurs , and the species continue to diverge until they can no longer mate and produce viable offspring . <hl> If reproductive barriers weaken , fusion occurs and the two species become one . Barriers remain the same if hybrids are fit and reproductive : stability may occur and hybridization continues .", "hl_sentences": "Hybrids can be either less fit than the parents , more fit , or about the same . Usually hybrids tend to be less fit ; therefore , such reproduction diminishes over time , nudging the two species to diverge further in a process called reinforcement . This term is used because the low success of the hybrids reinforces the original speciation . If the hybrids are as fit or more fit than the parents , the two species may fuse back into one species ( Figure 18.23 ) . If the hybrids are less fit than the parents , reinforcement of speciation occurs , and the species continue to diverge until they can no longer mate and produce viable offspring .", "question": { "cloze_format": "___ is a term used to describe the continued divergence of species based on the low fitness of hybrid offspring.", "normal_format": "Which term is used to describe the continued divergence of species based on the low fitness of hybrid offspring?", "question_choices": [ "reinforcement", "fusion", "stability", "punctuated equilibrium" ], "question_id": "fs-idp101132192", "question_text": "Which term is used to describe the continued divergence of species based on the low fitness of hybrid offspring?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 2, "ans_text": "ongoing gene flow among all individuals" }, "bloom": null, "hl_context": "<hl> In the gradual speciation model , species diverge gradually over time in small steps . <hl> <hl> In the punctuated equilibrium model , a new species undergoes changes quickly from the parent species , and then remains largely unchanged for long periods of time afterward ( Figure 18.23 ) . <hl> <hl> This early change model is called punctuated equilibrium , because it begins with a punctuated or periodic change and then remains in balance afterward . <hl> <hl> While punctuated equilibrium suggests a faster tempo , it does not necessarily exclude gradualism . <hl>", "hl_sentences": "In the gradual speciation model , species diverge gradually over time in small steps . In the punctuated equilibrium model , a new species undergoes changes quickly from the parent species , and then remains largely unchanged for long periods of time afterward ( Figure 18.23 ) . This early change model is called punctuated equilibrium , because it begins with a punctuated or periodic change and then remains in balance afterward . While punctuated equilibrium suggests a faster tempo , it does not necessarily exclude gradualism .", "question": { "cloze_format": "The component of speciation that would be least likely to be a part of punctuated equilibrium is (an) ___.", "normal_format": "Which components of speciation would be least likely to be a part of punctuated equilibrium?", "question_choices": [ "a division of populations", "a change in environmental conditions", "ongoing gene flow among all individuals", "a large number of mutations taking place at once" ], "question_id": "fs-idp10501840", "question_text": "Which components of speciation would be least likely to be a part of punctuated equilibrium?" }, "references_are_paraphrase": null } ]
18
18.1 Understanding Evolution Learning Objectives By the end of this section, you will be able to: Describe how the present-day theory of evolution was developed Define adaptation Explain convergent and divergent evolution Describe homologous and vestigial structures Discuss misconceptions about the theory of evolution Evolution by natural selection describes a mechanism for how species change over time. That species change had been suggested and debated well before Darwin began to explore this idea. The view that species were static and unchanging was grounded in the writings of Plato, yet there were also ancient Greeks who expressed evolutionary ideas. In the eighteenth century, ideas about the evolution of animals were reintroduced by the naturalist Georges-Louis Leclerc Comte de Buffon who observed that various geographic regions have different plant and animal populations, even when the environments are similar. It was also accepted that there were extinct species. During this time, James Hutton, a Scottish naturalist, proposed that geological change occurred gradually by the accumulation of small changes from processes operating like they are today over long periods of time. This contrasted with the predominant view that the geology of the planet was a consequence of catastrophic events occurring during a relatively brief past. Hutton’s view was popularized in the nineteenth century by the geologist Charles Lyell who became a friend to Darwin. Lyell’s ideas were influential on Darwin’s thinking: Lyell’s notion of the greater age of Earth gave more time for gradual change in species, and the process of change provided an analogy for gradual change in species. In the early nineteenth century, Jean-Baptiste Lamarck published a book that detailed a mechanism for evolutionary change. This mechanism is now referred to as an inheritance of acquired characteristics by which modifications in an individual are caused by its environment, or the use or disuse of a structure during its lifetime, could be inherited by its offspring and thus bring about change in a species. While this mechanism for evolutionary change was discredited, Lamarck’s ideas were an important influence on evolutionary thought. Charles Darwin and Natural Selection In the mid-nineteenth century, the actual mechanism for evolution was independently conceived of and described by two naturalists: Charles Darwin and Alfred Russel Wallace. Importantly, each naturalist spent time exploring the natural world on expeditions to the tropics. From 1831 to 1836, Darwin traveled around the world on H.M.S. Beagle , including stops in South America, Australia, and the southern tip of Africa. Wallace traveled to Brazil to collect insects in the Amazon rainforest from 1848 to 1852 and to the Malay Archipelago from 1854 to 1862. Darwin’s journey, like Wallace’s later journeys to the Malay Archipelago, included stops at several island chains, the last being the Galápagos Islands west of Ecuador. On these islands, Darwin observed species of organisms on different islands that were clearly similar, yet had distinct differences. For example, the ground finches inhabiting the Galápagos Islands comprised several species with a unique beak shape ( Figure 18.2 ). The species on the islands had a graded series of beak sizes and shapes with very small differences between the most similar. He observed that these finches closely resembled another finch species on the mainland of South America. Darwin imagined that the island species might be species modified from one of the original mainland species. Upon further study, he realized that the varied beaks of each finch helped the birds acquire a specific type of food. For example, seed-eating finches had stronger, thicker beaks for breaking seeds, and insect-eating finches had spear-like beaks for stabbing their prey. Wallace and Darwin both observed similar patterns in other organisms and they independently developed the same explanation for how and why such changes could take place. Darwin called this mechanism natural selection. Natural selection , also known as “survival of the fittest,” is the more prolific reproduction of individuals with favorable traits that survive environmental change because of those traits; this leads to evolutionary change. For example, a population of giant tortoises found in the Galapagos Archipelago was observed by Darwin to have longer necks than those that lived on other islands with dry lowlands. These tortoises were “selected” because they could reach more leaves and access more food than those with short necks. In times of drought when fewer leaves would be available, those that could reach more leaves had a better chance to eat and survive than those that couldn’t reach the food source. Consequently, long-necked tortoises would be more likely to be reproductively successful and pass the long-necked trait to their offspring. Over time, only long-necked tortoises would be present in the population. Natural selection, Darwin argued, was an inevitable outcome of three principles that operated in nature. First, most characteristics of organisms are inherited, or passed from parent to offspring. Although no one, including Darwin and Wallace, knew how this happened at the time, it was a common understanding. Second, more offspring are produced than are able to survive, so resources for survival and reproduction are limited. The capacity for reproduction in all organisms outstrips the availability of resources to support their numbers. Thus, there is competition for those resources in each generation. Both Darwin and Wallace’s understanding of this principle came from reading an essay by the economist Thomas Malthus who discussed this principle in relation to human populations. Third, offspring vary among each other in regard to their characteristics and those variations are inherited. Darwin and Wallace reasoned that offspring with inherited characteristics which allow them to best compete for limited resources will survive and have more offspring than those individuals with variations that are less able to compete. Because characteristics are inherited, these traits will be better represented in the next generation. This will lead to change in populations over generations in a process that Darwin called descent with modification. Ultimately, natural selection leads to greater adaptation of the population to its local environment; it is the only mechanism known for adaptive evolution. Papers by Darwin and Wallace ( Figure 18.3 ) presenting the idea of natural selection were read together in 1858 before the Linnean Society in London. The following year Darwin’s book, On the Origin of Species, was published. His book outlined in considerable detail his arguments for evolution by natural selection. Demonstrations of evolution by natural selection are time consuming and difficult to obtain. One of the best examples has been demonstrated in the very birds that helped to inspire Darwin’s theory: the Galápagos finches. Peter and Rosemary Grant and their colleagues have studied Galápagos finch populations every year since 1976 and have provided important demonstrations of natural selection. The Grants found changes from one generation to the next in the distribution of beak shapes with the medium ground finch on the Galápagos island of Daphne Major. The birds have inherited variation in the bill shape with some birds having wide deep bills and others having thinner bills. During a period in which rainfall was higher than normal because of an El Niño, the large hard seeds that large-billed birds ate were reduced in number; however, there was an abundance of the small soft seeds which the small-billed birds ate. Therefore, survival and reproduction were much better in the following years for the small-billed birds. In the years following this El Niño, the Grants measured beak sizes in the population and found that the average bill size was smaller. Since bill size is an inherited trait, parents with smaller bills had more offspring and the size of bills had evolved to be smaller. As conditions improved in 1987 and larger seeds became more available, the trend toward smaller average bill size ceased. Career Connection Field Biologist Many people hike, explore caves, scuba dive, or climb mountains for recreation. People often participate in these activities hoping to see wildlife. Experiencing the outdoors can be incredibly enjoyable and invigorating. What if your job was to be outside in the wilderness? Field biologists by definition work outdoors in the “field.” The term field in this case refers to any location outdoors, even under water. A field biologist typically focuses research on a certain species, group of organisms, or a single habitat ( Figure 18.4 ). One objective of many field biologists includes discovering new species that have never been recorded. Not only do such findings expand our understanding of the natural world, but they also lead to important innovations in fields such as medicine and agriculture. Plant and microbial species, in particular, can reveal new medicinal and nutritive knowledge. Other organisms can play key roles in ecosystems or be considered rare and in need of protection. When discovered, these important species can be used as evidence for environmental regulations and laws. Processes and Patterns of Evolution Natural selection can only take place if there is variation , or differences, among individuals in a population. Importantly, these differences must have some genetic basis; otherwise, the selection will not lead to change in the next generation. This is critical because variation among individuals can be caused by non-genetic reasons such as an individual being taller because of better nutrition rather than different genes. Genetic diversity in a population comes from two main mechanisms: mutation and sexual reproduction. Mutation, a change in DNA, is the ultimate source of new alleles, or new genetic variation in any population. The genetic changes caused by mutation can have one of three outcomes on the phenotype. A mutation affects the phenotype of the organism in a way that gives it reduced fitness—lower likelihood of survival or fewer offspring. A mutation may produce a phenotype with a beneficial effect on fitness. And, many mutations will also have no effect on the fitness of the phenotype; these are called neutral mutations. Mutations may also have a whole range of effect sizes on the fitness of the organism that expresses them in their phenotype, from a small effect to a great effect. Sexual reproduction also leads to genetic diversity: when two parents reproduce, unique combinations of alleles assemble to produce the unique genotypes and thus phenotypes in each of the offspring. A heritable trait that helps the survival and reproduction of an organism in its present environment is called an adaptation . Scientists describe groups of organisms becoming adapted to their environment when a change in the range of genetic variation occurs over time that increases or maintains the “fit” of the population to its environment. The webbed feet of platypuses are an adaptation for swimming. The snow leopards’ thick fur is an adaptation for living in the cold. The cheetahs’ fast speed is an adaptation for catching prey. Whether or not a trait is favorable depends on the environmental conditions at the time. The same traits are not always selected because environmental conditions can change. For example, consider a species of plant that grew in a moist climate and did not need to conserve water. Large leaves were selected because they allowed the plant to obtain more energy from the sun. Large leaves require more water to maintain than small leaves, and the moist environment provided favorable conditions to support large leaves. After thousands of years, the climate changed, and the area no longer had excess water. The direction of natural selection shifted so that plants with small leaves were selected because those populations were able to conserve water to survive the new environmental conditions. The evolution of species has resulted in enormous variation in form and function. Sometimes, evolution gives rise to groups of organisms that become tremendously different from each other. When two species evolve in diverse directions from a common point, it is called divergent evolution . Such divergent evolution can be seen in the forms of the reproductive organs of flowering plants which share the same basic anatomies; however, they can look very different as a result of selection in different physical environments and adaptation to different kinds of pollinators ( Figure 18.5 ). In other cases, similar phenotypes evolve independently in distantly related species. For example, flight has evolved in both bats and insects, and they both have structures we refer to as wings, which are adaptations to flight. However, the wings of bats and insects have evolved from very different original structures. This phenomenon is called convergent evolution , where similar traits evolve independently in species that do not share a common ancestry. The two species came to the same function, flying, but did so separately from each other. These physical changes occur over enormous spans of time and help explain how evolution occurs. Natural selection acts on individual organisms, which in turn can shape an entire species. Although natural selection may work in a single generation on an individual, it can take thousands or even millions of years for the genotype of an entire species to evolve. It is over these large time spans that life on earth has changed and continues to change. Evidence of Evolution The evidence for evolution is compelling and extensive. Looking at every level of organization in living systems, biologists see the signature of past and present evolution. Darwin dedicated a large portion of his book, On the Origin of Species , to identifying patterns in nature that were consistent with evolution, and since Darwin, our understanding has become clearer and broader. Fossils Fossils provide solid evidence that organisms from the past are not the same as those found today, and fossils show a progression of evolution. Scientists determine the age of fossils and categorize them from all over the world to determine when the organisms lived relative to each other. The resulting fossil record tells the story of the past and shows the evolution of form over millions of years ( Figure 18.6 ). For example, scientists have recovered highly detailed records showing the evolution of humans and horses ( Figure 18.6 ). The whale flipper shares a similar morphology to appendages of birds and mammals ( Figure 18.7 ) indicating that these species share a common ancestor. Anatomy and Embryology Another type of evidence for evolution is the presence of structures in organisms that share the same basic form. For example, the bones in the appendages of a human, dog, bird, and whale all share the same overall construction ( Figure 18.7 ) resulting from their origin in the appendages of a common ancestor. Over time, evolution led to changes in the shapes and sizes of these bones in different species, but they have maintained the same overall layout. Scientists call these synonymous parts homologous structures . Some structures exist in organisms that have no apparent function at all, and appear to be residual parts from a past common ancestor. These unused structures without function are called vestigial structures . Other examples of vestigial structures are wings on flightless birds, leaves on some cacti, and hind leg bones in whales. Link to Learning Visit this interactive site to guess which bones structures are homologous and which are analogous, and see examples of evolutionary adaptations to illustrate these concepts. Another evidence of evolution is the convergence of form in organisms that share similar environments. For example, species of unrelated animals, such as the arctic fox and ptarmigan, living in the arctic region have been selected for seasonal white phenotypes during winter to blend with the snow and ice ( Figure 18.8 ab ). These similarities occur not because of common ancestry, but because of similar selection pressures—the benefits of not being seen by predators. Embryology, the study of the development of the anatomy of an organism to its adult form, also provides evidence of relatedness between now widely divergent groups of organisms. Mutational tweaking in the embryo can have such magnified consequences in the adult that embryo formation tends to be conserved. As a result, structures that are absent in some groups often appear in their embryonic forms and disappear by the time the adult or juvenile form is reached. For example, all vertebrate embryos, including humans, exhibit gill slits and tails at some point in their early development. These disappear in the adults of terrestrial groups but are maintained in adult forms of aquatic groups such as fish and some amphibians. Great ape embryos, including humans, have a tail structure during their development that is lost by the time of birth. Biogeography The geographic distribution of organisms on the planet follows patterns that are best explained by evolution in conjunction with the movement of tectonic plates over geological time. Broad groups that evolved before the breakup of the supercontinent Pangaea (about 200 million years ago) are distributed worldwide. Groups that evolved since the breakup appear uniquely in regions of the planet, such as the unique flora and fauna of northern continents that formed from the supercontinent Laurasia and of the southern continents that formed from the supercontinent Gondwana. The presence of members of the plant family Proteaceae in Australia, southern Africa, and South America is best by their presence prior to the southern supercontinent Gondwana breaking up. The great diversification of marsupials in Australia and the absence of other mammals reflect Australia’s long isolation. Australia has an abundance of endemic species—species found nowhere else—which is typical of islands whose isolation by expanses of water prevents species to migrate. Over time, these species diverge evolutionarily into new species that look very different from their ancestors that may exist on the mainland. The marsupials of Australia, the finches on the Galápagos, and many species on the Hawaiian Islands are all unique to their one point of origin, yet they display distant relationships to ancestral species on mainlands. Molecular Biology Like anatomical structures, the structures of the molecules of life reflect descent with modification. Evidence of a common ancestor for all of life is reflected in the universality of DNA as the genetic material and in the near universality of the genetic code and the machinery of DNA replication and expression. Fundamental divisions in life between the three domains are reflected in major structural differences in otherwise conservative structures such as the components of ribosomes and the structures of membranes. In general, the relatedness of groups of organisms is reflected in the similarity of their DNA sequences—exactly the pattern that would be expected from descent and diversification from a common ancestor. DNA sequences have also shed light on some of the mechanisms of evolution. For example, it is clear that the evolution of new functions for proteins commonly occurs after gene duplication events that allow the free modification of one copy by mutation, selection, or drift (changes in a population’s gene pool resulting from chance), while the second copy continues to produce a functional protein. Misconceptions of Evolution Although the theory of evolution generated some controversy when it was first proposed, it was almost universally accepted by biologists, particularly younger biologists, within 20 years after publication of On the Origin of Species . Nevertheless, the theory of evolution is a difficult concept and misconceptions about how it works abound. Link to Learning This site addresses some of the main misconceptions associated with the theory of evolution. Evolution Is Just a Theory Critics of the theory of evolution dismiss its importance by purposefully confounding the everyday usage of the word “theory” with the way scientists use the word. In science, a “theory” is understood to be a body of thoroughly tested and verified explanations for a set of observations of the natural world. Scientists have a theory of the atom, a theory of gravity, and the theory of relativity, each of which describes understood facts about the world. In the same way, the theory of evolution describes facts about the living world. As such, a theory in science has survived significant efforts to discredit it by scientists. In contrast, a “theory” in common vernacular is a word meaning a guess or suggested explanation; this meaning is more akin to the scientific concept of “hypothesis.” When critics of evolution say evolution is “just a theory,” they are implying that there is little evidence supporting it and that it is still in the process of being rigorously tested. This is a mischaracterization. Individuals Evolve Evolution is the change in genetic composition of a population over time, specifically over generations, resulting from differential reproduction of individuals with certain alleles. Individuals do change over their lifetime, obviously, but this is called development and involves changes programmed by the set of genes the individual acquired at birth in coordination with the individual’s environment. When thinking about the evolution of a characteristic, it is probably best to think about the change of the average value of the characteristic in the population over time. For example, when natural selection leads to bill-size change in medium-ground finches in the Galápagos, this does not mean that individual bills on the finches are changing. If one measures the average bill size among all individuals in the population at one time and then measures the average bill size in the population several years later, this average value will be different as a result of evolution. Although some individuals may survive from the first time to the second, they will still have the same bill size; however, there will be many new individuals that contribute to the shift in average bill size. Evolution Explains the Origin of Life It is a common misunderstanding that evolution includes an explanation of life’s origins. Conversely, some of the theory’s critics believe that it cannot explain the origin of life. The theory does not try to explain the origin of life. The theory of evolution explains how populations change over time and how life diversifies the origin of species. It does not shed light on the beginnings of life including the origins of the first cells, which is how life is defined. The mechanisms of the origin of life on Earth are a particularly difficult problem because it occurred a very long time ago, and presumably it just occurred once. Importantly, biologists believe that the presence of life on Earth precludes the possibility that the events that led to life on Earth can be repeated because the intermediate stages would immediately become food for existing living things. However, once a mechanism of inheritance was in place in the form of a molecule like DNA either within a cell or pre-cell, these entities would be subject to the principle of natural selection. More effective reproducers would increase in frequency at the expense of inefficient reproducers. So while evolution does not explain the origin of life, it may have something to say about some of the processes operating once pre-living entities acquired certain properties. Organisms Evolve on Purpose Statements such as “organisms evolve in response to a change in an environment” are quite common, but such statements can lead to two types of misunderstandings. First, the statement must not be understood to mean that individual organisms evolve. The statement is shorthand for “a population evolves in response to a changing environment.” However, a second misunderstanding may arise by interpreting the statement to mean that the evolution is somehow intentional. A changed environment results in some individuals in the population, those with particular phenotypes, benefiting and therefore producing proportionately more offspring than other phenotypes. This results in change in the population if the characteristics are genetically determined. It is also important to understand that the variation that natural selection works on is already in a population and does not arise in response to an environmental change. For example, applying antibiotics to a population of bacteria will, over time, select a population of bacteria that are resistant to antibiotics. The resistance, which is caused by a gene, did not arise by mutation because of the application of the antibiotic. The gene for resistance was already present in the gene pool of the bacteria, likely at a low frequency. The antibiotic, which kills the bacterial cells without the resistance gene, strongly selects individuals that are resistant, since these would be the only ones that survived and divided. Experiments have demonstrated that mutations for antibiotic resistance do not arise as a result of antibiotic. In a larger sense, evolution is not goal directed. Species do not become “better” over time; they simply track their changing environment with adaptations that maximize their reproduction in a particular environment at a particular time. Evolution has no goal of making faster, bigger, more complex, or even smarter species, despite the commonness of this kind of language in popular discourse. What characteristics evolve in a species are a function of the variation present and the environment, both of which are constantly changing in a non-directional way. What trait is fit in one environment at one time may well be fatal at some point in the future. This holds equally well for a species of insect as it does the human species. 18.2 Formation of New Species Learning Objectives By the end of this section, you will be able to: Define species and describe how species are identified as different Describe genetic variables that lead to speciation Identify prezygotic and postzygotic reproductive barriers Explain allopatric and sympatric speciation Describe adaptive radiation Although all life on earth shares various genetic similarities, only certain organisms combine genetic information by sexual reproduction and have offspring that can then successfully reproduce. Scientists call such organisms members of the same biological species. Species and the Ability to Reproduce A species is a group of individual organisms that interbreed and produce fertile, viable offspring. According to this definition, one species is distinguished from another when, in nature, it is not possible for matings between individuals from each species to produce fertile offspring. Members of the same species share both external and internal characteristics, which develop from their DNA. The closer relationship two organisms share, the more DNA they have in common, just like people and their families. People’s DNA is likely to be more like their father or mother’s DNA than their cousin or grandparent’s DNA. Organisms of the same species have the highest level of DNA alignment and therefore share characteristics and behaviors that lead to successful reproduction. Species’ appearance can be misleading in suggesting an ability or inability to mate. For example, even though domestic dogs ( Canis lupus familiaris ) display phenotypic differences, such as size, build, and coat, most dogs can interbreed and produce viable puppies that can mature and sexually reproduce ( Figure 18.9 ). In other cases, individuals may appear similar although they are not members of the same species. For example, even though bald eagles ( Haliaeetus leucocephalus ) and African fish eagles ( Haliaeetus vocifer ) are both birds and eagles, each belongs to a separate species group ( Figure 18.10 ). If humans were to artificially intervene and fertilize the egg of a bald eagle with the sperm of an African fish eagle and a chick did hatch, that offspring, called a hybrid (a cross between two species), would probably be infertile—unable to successfully reproduce after it reached maturity. Different species may have different genes that are active in development; therefore, it may not be possible to develop a viable offspring with two different sets of directions. Thus, even though hybridization may take place, the two species still remain separate. Populations of species share a gene pool: a collection of all the variants of genes in the species. Again, the basis to any changes in a group or population of organisms must be genetic for this is the only way to share and pass on traits. When variations occur within a species, they can only be passed to the next generation along two main pathways: asexual reproduction or sexual reproduction. The change will be passed on asexually simply if the reproducing cell possesses the changed trait. For the changed trait to be passed on by sexual reproduction, a gamete, such as a sperm or egg cell, must possess the changed trait. In other words, sexually-reproducing organisms can experience several genetic changes in their body cells, but if these changes do not occur in a sperm or egg cell, the changed trait will never reach the next generation. Only heritable traits can evolve. Therefore, reproduction plays a paramount role for genetic change to take root in a population or species. In short, organisms must be able to reproduce with each other to pass new traits to offspring. Speciation The biological definition of species, which works for sexually reproducing organisms, is a group of actually or potentially interbreeding individuals. There are exceptions to this rule. Many species are similar enough that hybrid offspring are possible and may often occur in nature, but for the majority of species this rule generally holds. In fact, the presence in nature of hybrids between similar species suggests that they may have descended from a single interbreeding species, and the speciation process may not yet be completed. Given the extraordinary diversity of life on the planet there must be mechanisms for speciation : the formation of two species from one original species. Darwin envisioned this process as a branching event and diagrammed the process in the only illustration found in On the Origin of Species ( Figure 18.11 a ). Compare this illustration to the diagram of elephant evolution ( Figure 18.11 b ), which shows that as one species changes over time, it branches to form more than one new species, repeatedly, as long as the population survives or until the organism becomes extinct. For speciation to occur, two new populations must be formed from one original population and they must evolve in such a way that it becomes impossible for individuals from the two new populations to interbreed. Biologists have proposed mechanisms by which this could occur that fall into two broad categories. Allopatric speciation (allo- = "other"; -patric = "homeland") involves geographic separation of populations from a parent species and subsequent evolution. Sympatric speciation (sym- = "same"; -patric = "homeland") involves speciation occurring within a parent species remaining in one location. Biologists think of speciation events as the splitting of one ancestral species into two descendant species. There is no reason why there might not be more than two species formed at one time except that it is less likely and multiple events can be conceptualized as single splits occurring close in time. Allopatric Speciation A geographically continuous population has a gene pool that is relatively homogeneous. Gene flow, the movement of alleles across the range of the species, is relatively free because individuals can move and then mate with individuals in their new location. Thus, the frequency of an allele at one end of a distribution will be similar to the frequency of the allele at the other end. When populations become geographically discontinuous, that free-flow of alleles is prevented. When that separation lasts for a period of time, the two populations are able to evolve along different trajectories. Thus, their allele frequencies at numerous genetic loci gradually become more and more different as new alleles independently arise by mutation in each population. Typically, environmental conditions, such as climate, resources, predators, and competitors for the two populations will differ causing natural selection to favor divergent adaptations in each group. Isolation of populations leading to allopatric speciation can occur in a variety of ways: a river forming a new branch, erosion forming a new valley, a group of organisms traveling to a new location without the ability to return, or seeds floating over the ocean to an island. The nature of the geographic separation necessary to isolate populations depends entirely on the biology of the organism and its potential for dispersal. If two flying insect populations took up residence in separate nearby valleys, chances are, individuals from each population would fly back and forth continuing gene flow. However, if two rodent populations became divided by the formation of a new lake, continued gene flow would be unlikely; therefore, speciation would be more likely. Biologists group allopatric processes into two categories: dispersal and vicariance. Dispersal is when a few members of a species move to a new geographical area, and vicariance is when a natural situation arises to physically divide organisms. Scientists have documented numerous cases of allopatric speciation taking place. For example, along the west coast of the United States, two separate sub-species of spotted owls exist. The northern spotted owl has genetic and phenotypic differences from its close relative: the Mexican spotted owl, which lives in the south ( Figure 18.12 ). Additionally, scientists have found that the further the distance between two groups that once were the same species, the more likely it is that speciation will occur. This seems logical because as the distance increases, the various environmental factors would likely have less in common than locations in close proximity. Consider the two owls: in the north, the climate is cooler than in the south; the types of organisms in each ecosystem differ, as do their behaviors and habits; also, the hunting habits and prey choices of the southern owls vary from the northern owls. These variances can lead to evolved differences in the owls, and speciation likely will occur. Adaptive Radiation In some cases, a population of one species disperses throughout an area, and each finds a distinct niche or isolated habitat. Over time, the varied demands of their new lifestyles lead to multiple speciation events originating from a single species. This is called adaptive radiation because many adaptations evolve from a single point of origin; thus, causing the species to radiate into several new ones. Island archipelagos like the Hawaiian Islands provide an ideal context for adaptive radiation events because water surrounds each island which leads to geographical isolation for many organisms. The Hawaiian honeycreeper illustrates one example of adaptive radiation. From a single species, called the founder species, numerous species have evolved, including the six shown in Figure 18.13 . Notice the differences in the species’ beaks in Figure 18.13 . Evolution in response to natural selection based on specific food sources in each new habitat led to evolution of a different beak suited to the specific food source. The seed-eating bird has a thicker, stronger beak which is suited to break hard nuts. The nectar-eating birds have long beaks to dip into flowers to reach the nectar. The insect-eating birds have beaks like swords, appropriate for stabbing and impaling insects. Darwin’s finches are another example of adaptive radiation in an archipelago. Link to Learning Click through this interactive site to see how island birds evolved in evolutionary increments from 5 million years ago to today. Sympatric Speciation Can divergence occur if no physical barriers are in place to separate individuals who continue to live and reproduce in the same habitat? The answer is yes. The process of speciation within the same space is called sympatric speciation; the prefix “sym” means same, so “sympatric” means “same homeland” in contrast to “allopatric” meaning “other homeland.” A number of mechanisms for sympatric speciation have been proposed and studied. One form of sympatric speciation can begin with a serious chromosomal error during cell division. In a normal cell division event chromosomes replicate, pair up, and then separate so that each new cell has the same number of chromosomes. However, sometimes the pairs separate and the end cell product has too many or too few individual chromosomes in a condition called aneuploidy ( Figure 18.14 ). Visual Connection Which is most likely to survive, offspring with 2 n +1 chromosomes or offspring with 2 n -1 chromosomes? Polyploidy is a condition in which a cell or organism has an extra set, or sets, of chromosomes. Scientists have identified two main types of polyploidy that can lead to reproductive isolation of an individual in the polyploidy state. Reproductive isolation is the inability to interbreed. In some cases, a polyploid individual will have two or more complete sets of chromosomes from its own species in a condition called autopolyploidy ( Figure 18.15 ). The prefix “auto-” means “self,” so the term means multiple chromosomes from one’s own species. Polyploidy results from an error in meiosis in which all of the chromosomes move into one cell instead of separating. For example, if a plant species with 2 n = 6 produces autopolyploid gametes that are also diploid (2 n = 6, when they should be n = 3), the gametes now have twice as many chromosomes as they should have. These new gametes will be incompatible with the normal gametes produced by this plant species. However, they could either self-pollinate or reproduce with other autopolyploid plants with gametes having the same diploid number. In this way, sympatric speciation can occur quickly by forming offspring with 4 n called a tetraploid. These individuals would immediately be able to reproduce only with those of this new kind and not those of the ancestral species. The other form of polyploidy occurs when individuals of two different species reproduce to form a viable offspring called an allopolyploid . The prefix “allo-” means “other” (recall from allopatric): therefore, an allopolyploid occurs when gametes from two different species combine. Figure 18.16 illustrates one possible way an allopolyploid can form. Notice how it takes two generations, or two reproductive acts, before the viable fertile hybrid results. The cultivated forms of wheat, cotton, and tobacco plants are all allopolyploids. Although polyploidy occurs occasionally in animals, it takes place most commonly in plants. (Animals with any of the types of chromosomal aberrations described here are unlikely to survive and produce normal offspring.) Scientists have discovered more than half of all plant species studied relate back to a species evolved through polyploidy. With such a high rate of polyploidy in plants, some scientists hypothesize that this mechanism takes place more as an adaptation than as an error. Reproductive Isolation Given enough time, the genetic and phenotypic divergence between populations will affect characters that influence reproduction: if individuals of the two populations were to be brought together, mating would be less likely, but if mating occurred, offspring would be non-viable or infertile. Many types of diverging characters may affect the reproductive isolation , the ability to interbreed, of the two populations. Reproductive isolation can take place in a variety of ways. Scientists organize them into two groups: prezygotic barriers and postzygotic barriers. Recall that a zygote is a fertilized egg: the first cell of the development of an organism that reproduces sexually. Therefore, a prezygotic barrier is a mechanism that blocks reproduction from taking place; this includes barriers that prevent fertilization when organisms attempt reproduction. A postzygotic barrier occurs after zygote formation; this includes organisms that don’t survive the embryonic stage and those that are born sterile. Some types of prezygotic barriers prevent reproduction entirely. Many organisms only reproduce at certain times of the year, often just annually. Differences in breeding schedules, called temporal isolation , can act as a form of reproductive isolation. For example, two species of frogs inhabit the same area, but one reproduces from January to March, whereas the other reproduces from March to May ( Figure 18.17 ). In some cases, populations of a species move or are moved to a new habitat and take up residence in a place that no longer overlaps with the other populations of the same species. This situation is called habitat isolation . Reproduction with the parent species ceases, and a new group exists that is now reproductively and genetically independent. For example, a cricket population that was divided after a flood could no longer interact with each other. Over time, the forces of natural selection, mutation, and genetic drift will likely result in the divergence of the two groups ( Figure 18.18 ). Behavioral isolation occurs when the presence or absence of a specific behavior prevents reproduction from taking place. For example, male fireflies use specific light patterns to attract females. Various species of fireflies display their lights differently. If a male of one species tried to attract the female of another, she would not recognize the light pattern and would not mate with the male. Other prezygotic barriers work when differences in their gamete cells (eggs and sperm) prevent fertilization from taking place; this is called a gametic barrier . Similarly, in some cases closely related organisms try to mate, but their reproductive structures simply do not fit together. For example, damselfly males of different species have differently shaped reproductive organs. If one species tries to mate with the female of another, their body parts simply do not fit together. ( Figure 18.19 ). In plants, certain structures aimed to attract one type of pollinator simultaneously prevent a different pollinator from accessing the pollen. The tunnel through which an animal must access nectar can vary widely in length and diameter, which prevents the plant from being cross-pollinated with a different species ( Figure 18.20 ). When fertilization takes place and a zygote forms, postzygotic barriers can prevent reproduction. Hybrid individuals in many cases cannot form normally in the womb and simply do not survive past the embryonic stages. This is called hybrid inviability because the hybrid organisms simply are not viable. In another postzygotic situation, reproduction leads to the birth and growth of a hybrid that is sterile and unable to reproduce offspring of their own; this is called hybrid sterility. Habitat Influence on Speciation Sympatric speciation may also take place in ways other than polyploidy. For example, consider a species of fish that lives in a lake. As the population grows, competition for food also grows. Under pressure to find food, suppose that a group of these fish had the genetic flexibility to discover and feed off another resource that was unused by the other fish. What if this new food source was found at a different depth of the lake? Over time, those feeding on the second food source would interact more with each other than the other fish; therefore, they would breed together as well. Offspring of these fish would likely behave as their parents: feeding and living in the same area and keeping separate from the original population. If this group of fish continued to remain separate from the first population, eventually sympatric speciation might occur as more genetic differences accumulated between them. This scenario does play out in nature, as do others that lead to reproductive isolation. One such place is Lake Victoria in Africa, famous for its sympatric speciation of cichlid fish. Researchers have found hundreds of sympatric speciation events in these fish, which have not only happened in great number, but also over a short period of time. Figure 18.21 shows this type of speciation among a cichlid fish population in Nicaragua. In this locale, two types of cichlids live in the same geographic location but have come to have different morphologies that allow them to eat various food sources. 18.3 Reconnection and Rates of Speciation Learning Objectives By the end of this section, you will be able to: Describe pathways of species evolution in hybrid zones Explain the two major theories on rates of speciation Speciation occurs over a span of evolutionary time, so when a new species arises, there is a transition period during which the closely related species continue to interact. Reconnection After speciation, two species may recombine or even continue interacting indefinitely. Individual organisms will mate with any nearby individual who they are capable of breeding with. An area where two closely related species continue to interact and reproduce, forming hybrids, is called a hybrid zone . Over time, the hybrid zone may change depending on the fitness of the hybrids and the reproductive barriers ( Figure 18.22 ). If the hybrids are less fit than the parents, reinforcement of speciation occurs, and the species continue to diverge until they can no longer mate and produce viable offspring. If reproductive barriers weaken, fusion occurs and the two species become one. Barriers remain the same if hybrids are fit and reproductive: stability may occur and hybridization continues. Visual Connection If two species eat a different diet but one of the food sources is eliminated and both species are forced to eat the same foods, what change in the hybrid zone is most likely to occur? Hybrids can be either less fit than the parents, more fit, or about the same. Usually hybrids tend to be less fit; therefore, such reproduction diminishes over time, nudging the two species to diverge further in a process called reinforcement . This term is used because the low success of the hybrids reinforces the original speciation. If the hybrids are as fit or more fit than the parents, the two species may fuse back into one species ( Figure 18.23 ). Scientists have also observed that sometimes two species will remain separate but also continue to interact to produce some hybrid individuals; this is classified as stability because no real net change is taking place. Varying Rates of Speciation Scientists around the world study speciation, documenting observations both of living organisms and those found in the fossil record. As their ideas take shape and as research reveals new details about how life evolves, they develop models to help explain rates of speciation. In terms of how quickly speciation occurs, two patterns are currently observed: gradual speciation model and punctuated equilibrium model. In the gradual speciation model , species diverge gradually over time in small steps. In the punctuated equilibrium model, a new species undergoes changes quickly from the parent species, and then remains largely unchanged for long periods of time afterward ( Figure 18.23 ). This early change model is called punctuated equilibrium, because it begins with a punctuated or periodic change and then remains in balance afterward. While punctuated equilibrium suggests a faster tempo, it does not necessarily exclude gradualism. Visual Connection Which of the following statements is false? Punctuated equilibrium is most likely to occur in a small population that experiences a rapid change in its environment. Punctuated equilibrium is most likely to occur in a large population that lives in a stable climate. Gradual speciation is most likely to occur in species that live in a stable climate. Gradual speciation and punctuated equilibrium both result in the divergence of species. The primary influencing factor on changes in speciation rate is environmental conditions. Under some conditions, selection occurs quickly or radically. Consider a species of snails that had been living with the same basic form for many thousands of years. Layers of their fossils would appear similar for a long time. When a change in the environment takes place—such as a drop in the water level—a small number of organisms are separated from the rest in a brief period of time, essentially forming one large and one tiny population. The tiny population faces new environmental conditions. Because its gene pool quickly became so small, any variation that surfaces and that aids in surviving the new conditions becomes the predominant form. Link to Learning Visit this website to continue the speciation story of the snails.
anatomy_and_physiology
Chapter Objectives After studying this chapter, you will be able to: Describe the structure and function of the cell membrane, including its regulation of materials into and out of the cell Describe the functions of the various cytoplasmic organelles Explain the structure and contents of the nucleus, as well as the process of DNA replication Explain the process by which a cell builds proteins using the DNA code List the stages of the cell cycle in order, including the steps of cell division in somatic cells Discuss how a cell differentiates and becomes more specialized List the morphological and physiological characteristics of some representative cell types in the human body Introduction You developed from a single fertilized egg cell into the complex organism containing trillions of cells that you see when you look in a mirror. During this developmental process, early, undifferentiated cells differentiate and become specialized in their structure and function. These different cell types form specialized tissues that work in concert to perform all of the functions necessary for the living organism. Cellular and developmental biologists study how the continued division of a single cell leads to such complexity and differentiation. Consider the difference between a structural cell in the skin and a nerve cell. A structural skin cell may be shaped like a flat plate (squamous) and live only for a short time before it is shed and replaced. Packed tightly into rows and sheets, the squamous skin cells provide a protective barrier for the cells and tissues that lie beneath. A nerve cell, on the other hand, may be shaped something like a star, sending out long processes up to a meter in length and may live for the entire lifetime of the organism. With their long winding appendages, nerve cells can communicate with one another and with other types of body cells and send rapid signals that inform the organism about its environment and allow it to interact with that environment. These differences illustrate one very important theme that is consistent at all organizational levels of biology: the form of a structure is optimally suited to perform particular functions assigned to that structure. Keep this theme in mind as you tour the inside of a cell and are introduced to the various types of cells in the body. A primary responsibility of each cell is to contribute to homeostasis. Homeostasis is a term used in biology that refers to a dynamic state of balance within parameters that are compatible with life. For example, living cells require a water-based environment to survive in, and there are various physical (anatomical) and physiological mechanisms that keep all of the trillions of living cells in the human body moist. This is one aspect of homeostasis. When a particular parameter, such as blood pressure or blood oxygen content, moves far enough out of homeostasis (generally becoming too high or too low), illness or disease—and sometimes death—inevitably results. The concept of a cell started with microscopic observations of dead cork tissue by scientist Robert Hooke in 1665. Without realizing their function or importance, Hook coined the term “cell” based on the resemblance of the small subdivisions in the cork to the rooms that monks inhabited, called cells. About ten years later, Antonie van Leeuwenhoek became the first person to observe living and moving cells under a microscope. In the century that followed, the theory that cells represented the basic unit of life would develop. These tiny fluid-filled sacs house components responsible for the thousands of biochemical reactions necessary for an organism to grow and survive. In this chapter, you will learn about the major components and functions of a prototypical, generalized cell and discover some of the different types of cells in the human body.
[ { "answer": { "ans_choice": 1, "ans_text": "integral proteins" }, "bloom": "1", "hl_context": "The lipid bilayer forms the basis of the cell membrane , but it is peppered throughout with various proteins . Two different types of proteins that are commonly associated with the cell membrane are the integral proteins and peripheral protein ( Figure 3.4 ) . <hl> As its name suggests , an integral protein is a protein that is embedded in the membrane . <hl> A channel protein is an example of an integral protein that selectively allows particular materials , such as certain ions , to pass into or out of the cell .", "hl_sentences": "As its name suggests , an integral protein is a protein that is embedded in the membrane .", "question": { "cloze_format": "Because they are embedded within the membrane, ion channels are examples of ________.", "normal_format": "Because they are embedded within the membrane, ion channels are examples of what?", "question_choices": [ "receptor proteins", "integral proteins", "peripheral proteins", "glycoproteins" ], "question_id": "fs-id1509790", "question_text": "Because they are embedded within the membrane, ion channels are examples of ________." }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 3, "ans_text": "down; concentration" }, "bloom": null, "hl_context": "Another mechanism besides diffusion to passively transport materials between compartments is filtration . <hl> Unlike diffusion of a substance from where it is more concentrated to less concentrated , filtration uses a hydrostatic pressure gradient that pushes the fluid — and the solutes within it — from a higher pressure area to a lower pressure area . <hl> Filtration is an extremely important process in the body . For example , the circulatory system uses filtration to move plasma and substances across the endothelial lining of capillaries and into surrounding tissues , supplying cells with the nutrients . Filtration pressure in the kidneys provides the mechanism to remove wastes from the bloodstream . In order to understand how substances move passively across a cell membrane , it is necessary to understand concentration gradients and diffusion . A concentration gradient is the difference in concentration of a substance across a space . Molecules ( or ions ) will spread / diffuse from where they are more concentrated to where they are less concentrated until they are equally distributed in that space . <hl> ( When molecules move in this way , they are said to move down their concentration gradient . ) <hl> Diffusion is the movement of particles from an area of higher concentration to an area of lower concentration . A couple of common examples will help to illustrate this concept . Imagine being inside a closed bathroom . If a bottle of perfume were sprayed , the scent molecules would naturally diffuse from the spot where they left the bottle to all corners of the bathroom , and this diffusion would go on until no more concentration gradient remains . Another example is a spoonful of sugar placed in a cup of tea . Eventually the sugar will diffuse throughout the tea until no concentration gradient remains . In both cases , if the room is warmer or the tea hotter , diffusion occurs even faster as the molecules are bumping into each other and spreading out faster than at cooler temperatures . Having an internal body temperature around 98.6 ° F thus also aids in diffusion of particles within the body .", "hl_sentences": "Unlike diffusion of a substance from where it is more concentrated to less concentrated , filtration uses a hydrostatic pressure gradient that pushes the fluid — and the solutes within it — from a higher pressure area to a lower pressure area . ( When molecules move in this way , they are said to move down their concentration gradient . )", "question": { "cloze_format": "The diffusion of substances within a solution tends to move those substances ________ their ________ gradient.", "normal_format": "The diffusion of substances within a solution tends to move them where to their what gradient?", "question_choices": [ "up; electrical", "up; electrochemical", "down; pressure", "down; concentration" ], "question_id": "fs-id1490602", "question_text": "The diffusion of substances within a solution tends to move those substances ________ their ________ gradient." }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 2, "ans_text": "active transport" }, "bloom": null, "hl_context": "The sodium-potassium pump , which is also called Na + / K + ATPase , transports sodium out of a cell while moving potassium into the cell . The Na + / K + pump is an important ion pump found in the membranes of many types of cells . These pumps are particularly abundant in nerve cells , which are constantly pumping out sodium ions and pulling in potassium ions to maintain an electrical gradient across their cell membranes . An electrical gradient is a difference in electrical charge across a space . In the case of nerve cells , for example , the electrical gradient exists between the inside and outside of the cell , with the inside being negatively-charged ( at around - 70 mV ) relative to the outside . The negative electrical gradient is maintained because each Na + / K + pump moves three Na + ions out of the cell and two K + ions into the cell for each ATP molecule that is used ( Figure 3.9 ) . This process is so important for nerve cells that it accounts for the majority of their ATP usage . <hl> Active transport pumps can also work together with other active or passive transport systems to move substances across the membrane . <hl> For example , the sodium-potassium pump maintains a high concentration of sodium ions outside of the cell . Therefore , if the cell needs sodium ions , all it has to do is open a passive sodium channel , as the concentration gradient of the sodium ions will drive them to diffuse into the cell . <hl> In this way , the action of an active transport pump ( the sodium-potassium pump ) powers the passive transport of sodium ions by creating a concentration gradient . <hl> When active transport powers the transport of another substance in this way , it is called secondary active transport . Symporters are secondary active transporters that move two substances in the same direction . For example , the sodium-glucose symporter uses sodium ions to “ pull ” glucose molecules into the cell . Because cells store glucose for energy , glucose is typically at a higher concentration inside of the cell than outside . However , due to the action of the sodium-potassium pump , sodium ions will easily diffuse into the cell when the symporter is opened . The flood of sodium ions through the symporter provides the energy that allows glucose to move through the symporter and into the cell , against its concentration gradient . Conversely , antiporters are secondary active transport systems that transport substances in opposite directions . For example , the sodium-hydrogen ion antiporter uses the energy from the inward flood of sodium ions to move hydrogen ions ( H + ) out of the cell . The sodium-hydrogen antiporter is used to maintain the pH of the cell's interior . <hl> Other forms of active transport do not involve membrane carriers . <hl> <hl> Endocytosis ( bringing “ into the cell ” ) is the process of a cell ingesting material by enveloping it in a portion of its cell membrane , and then pinching off that portion of membrane ( Figure 3.10 ) . <hl> Once pinched off , the portion of membrane and its contents becomes an independent , intracellular vesicle . A vesicle is a membranous sac — a spherical and hollow organelle bounded by a lipid bilayer membrane . Endocytosis often brings materials into the cell that must to be broken down or digested . <hl> Phagocytosis ( “ cell eating ” ) is the endocytosis of large particles . <hl> <hl> Many immune cells engage in phagocytosis of invading pathogens . <hl> Like little Pac-men , their job is to patrol body tissues for unwanted matter , such as invading bacterial cells , phagocytize them , and digest them . In contrast to phagocytosis , pinocytosis ( “ cell drinking ” ) brings fluid containing dissolved substances into a cell through membrane vesicles .", "hl_sentences": "Active transport pumps can also work together with other active or passive transport systems to move substances across the membrane . In this way , the action of an active transport pump ( the sodium-potassium pump ) powers the passive transport of sodium ions by creating a concentration gradient . Other forms of active transport do not involve membrane carriers . Endocytosis ( bringing “ into the cell ” ) is the process of a cell ingesting material by enveloping it in a portion of its cell membrane , and then pinching off that portion of membrane ( Figure 3.10 ) . Phagocytosis ( “ cell eating ” ) is the endocytosis of large particles . Many immune cells engage in phagocytosis of invading pathogens .", "question": { "cloze_format": "Ion pumps and phagocytosis are both examples of ________.", "normal_format": "What are ion pumps and phagocytosis both examples of?", "question_choices": [ "endocytosis", "passive transport", "active transport", "facilitated diffusion" ], "question_id": "fs-id1506227", "question_text": "Ion pumps and phagocytosis are both examples of ________." }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 3, "ans_text": "the water" }, "bloom": null, "hl_context": "Now that you have learned that the cell membrane surrounds all cells , you can dive inside of a prototypical human cell to learn about its internal components and their functions . <hl> All living cells in multicellular organisms contain an internal cytoplasmic compartment , and a nucleus within the cytoplasm . <hl> <hl> Cytosol , the jelly-like substance within the cell , provides the fluid medium necessary for biochemical reactions . <hl> Eukaryotic cells , including all animal cells , also contain various cellular organelles . An organelle ( “ little organ ” ) is one of several different types of membrane-enclosed bodies in the cell , each performing a unique function . Just as the various bodily organs work together in harmony to perform all of a human ’ s functions , the many different cellular organelles work together to keep the cell healthy and performing all of its important functions . <hl> The organelles and cytosol , taken together , compose the cell ’ s cytoplasm . <hl> The nucleus is a cell ’ s central organelle , which contains the cell ’ s DNA ( Figure 3.13 ) .", "hl_sentences": "All living cells in multicellular organisms contain an internal cytoplasmic compartment , and a nucleus within the cytoplasm . Cytosol , the jelly-like substance within the cell , provides the fluid medium necessary for biochemical reactions . The organelles and cytosol , taken together , compose the cell ’ s cytoplasm .", "question": { "cloze_format": "Choose the term that best completes the following analogy: Cytoplasm is to cytosol as a swimming pool containing chlorine and flotation toys is to ________.", "normal_format": "Cytoplasm is to cytosol as a swimming pool containing chlorine and flotation toys is to what?", "question_choices": [ "the walls of the pool", "the chlorine", "the flotation toys", "the water" ], "question_id": "fs-id1514835", "question_text": "Choose the term that best completes the following analogy: Cytoplasm is to cytosol as a swimming pool containing chlorine and flotation toys is to ________." }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 1, "ans_text": "ribosomes" }, "bloom": "1", "hl_context": "In contrast with the smooth ER , the primary job of the rough ER is the synthesis and modification of proteins destined for the cell membrane or for export from the cell . <hl> For this protein synthesis , many ribosomes attach to the ER ( giving it the studded appearance of rough ER ) . <hl> Typically , a protein is synthesized within the ribosome and released inside the channel of the rough ER , where sugars can be added to it ( by a process called glycosylation ) before it is transported within a vesicle to the next stage in the packaging and shipping process : the Golgi apparatus . The endoplasmic reticulum ( ER ) is a system of channels that is continuous with the nuclear membrane ( or “ envelope ” ) covering the nucleus and composed of the same lipid bilayer material . The ER can be thought of as a series of winding thoroughfares similar to the waterway canals in Venice . The ER provides passages throughout much of the cell that function in transporting , synthesizing , and storing materials . The winding structure of the ER results in a large membranous surface area that supports its many functions ( Figure 3.14 ) . Endoplasmic reticulum can exist in two forms : rough ER and smooth ER . These two types of ER perform some very different functions and can be found in very different amounts depending on the type of cell . <hl> Rough ER ( RER ) is so-called because its membrane is dotted with embedded granules — organelles called ribosomes , giving the RER a bumpy appearance . <hl> A ribosome is an organelle that serves as the site of protein synthesis . It is composed of two ribosomal RNA subunits that wrap around mRNA to start the process of translation , followed by protein synthesis . Smooth ER ( SER ) lacks these ribosomes .", "hl_sentences": "For this protein synthesis , many ribosomes attach to the ER ( giving it the studded appearance of rough ER ) . Rough ER ( RER ) is so-called because its membrane is dotted with embedded granules — organelles called ribosomes , giving the RER a bumpy appearance .", "question": { "cloze_format": "The associated structures the rough ER has its name due to are ___.", "normal_format": "The rough ER has its name due to what associated structures?", "question_choices": [ "Golgi apparatus", "ribosomes", "lysosomes", "proteins" ], "question_id": "fs-id1286938", "question_text": "The rough ER has its name due to what associated structures?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 0, "ans_text": "production of proteins" }, "bloom": "1", "hl_context": "<hl> In contrast with the smooth ER , the primary job of the rough ER is the synthesis and modification of proteins destined for the cell membrane or for export from the cell . <hl> <hl> For this protein synthesis , many ribosomes attach to the ER ( giving it the studded appearance of rough ER ) . <hl> Typically , a protein is synthesized within the ribosome and released inside the channel of the rough ER , where sugars can be added to it ( by a process called glycosylation ) before it is transported within a vesicle to the next stage in the packaging and shipping process : the Golgi apparatus . The endoplasmic reticulum ( ER ) is a system of channels that is continuous with the nuclear membrane ( or “ envelope ” ) covering the nucleus and composed of the same lipid bilayer material . The ER can be thought of as a series of winding thoroughfares similar to the waterway canals in Venice . The ER provides passages throughout much of the cell that function in transporting , synthesizing , and storing materials . The winding structure of the ER results in a large membranous surface area that supports its many functions ( Figure 3.14 ) . Endoplasmic reticulum can exist in two forms : rough ER and smooth ER . These two types of ER perform some very different functions and can be found in very different amounts depending on the type of cell . <hl> Rough ER ( RER ) is so-called because its membrane is dotted with embedded granules — organelles called ribosomes , giving the RER a bumpy appearance . <hl> <hl> A ribosome is an organelle that serves as the site of protein synthesis . <hl> It is composed of two ribosomal RNA subunits that wrap around mRNA to start the process of translation , followed by protein synthesis . Smooth ER ( SER ) lacks these ribosomes .", "hl_sentences": "In contrast with the smooth ER , the primary job of the rough ER is the synthesis and modification of proteins destined for the cell membrane or for export from the cell . For this protein synthesis , many ribosomes attach to the ER ( giving it the studded appearance of rough ER ) . Rough ER ( RER ) is so-called because its membrane is dotted with embedded granules — organelles called ribosomes , giving the RER a bumpy appearance . A ribosome is an organelle that serves as the site of protein synthesis .", "question": { "cloze_format": "The ___ is a function of the rough ER.", "normal_format": "Which of the following is a function of the rough ER?", "question_choices": [ "production of proteins", "detoxification of certain substances", "synthesis of steroid hormones", "regulation of intracellular calcium concentration" ], "question_id": "fs-id1517273", "question_text": "Which of the following is a function of the rough ER?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 2, "ans_text": "They are all polymers of protein subunits." }, "bloom": null, "hl_context": "Much like the bony skeleton structurally supports the human body , the cytoskeleton helps the cells to maintain their structural integrity . <hl> The cytoskeleton is a group of fibrous proteins that provide structural support for cells , but this is only one of the functions of the cytoskeleton . <hl> Cytoskeletal components are also critical for cell motility , cell reproduction , and transportation of substances within the cell .", "hl_sentences": "The cytoskeleton is a group of fibrous proteins that provide structural support for cells , but this is only one of the functions of the cytoskeleton .", "question": { "cloze_format": "A feature common to all three components of the cytoskeleton is that ___ .", "normal_format": "Which of the following is a feature common to all three components of the cytoskeleton?", "question_choices": [ "They all serve to scaffold the organelles within the cell.", "They are all characterized by roughly the same diameter.", "They are all polymers of protein subunits.", "They all help the cell resist compression and tension." ], "question_id": "fs-id1739716", "question_text": "Which of the following is a feature common to all three components of the cytoskeleton?" }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 0, "ans_text": "mitochondria" }, "bloom": "1", "hl_context": "<hl> A mitochondrion ( plural = mitochondria ) is a membranous , bean-shaped organelle that is the “ energy transformer ” of the cell . <hl> Mitochondria consist of an outer lipid bilayer membrane as well as an additional inner lipid bilayer membrane ( Figure 3.16 ) . The inner membrane is highly folded into winding structures with a great deal of surface area , called cristae . It is along this inner membrane that a series of proteins , enzymes , and other molecules perform the biochemical reactions of cellular respiration . <hl> These reactions convert energy stored in nutrient molecules ( such as glucose ) into adenosine triphosphate ( ATP ) , which provides usable cellular energy to the cell . <hl> <hl> Cells use ATP constantly , and so the mitochondria are constantly at work . <hl> Oxygen molecules are required during cellular respiration , which is why you must constantly breathe it in . One of the organ systems in the body that uses huge amounts of ATP is the muscular system because ATP is required to sustain muscle contraction . As a result , muscle cells are packed full of mitochondria . Nerve cells also need large quantities of ATP to run their sodium-potassium pumps . Therefore , an individual neuron will be loaded with over a thousand mitochondria . On the other hand , a bone cell , which is not nearly as metabolically-active , might only have a couple hundred mitochondria .", "hl_sentences": "A mitochondrion ( plural = mitochondria ) is a membranous , bean-shaped organelle that is the “ energy transformer ” of the cell . These reactions convert energy stored in nutrient molecules ( such as glucose ) into adenosine triphosphate ( ATP ) , which provides usable cellular energy to the cell . Cells use ATP constantly , and so the mitochondria are constantly at work .", "question": { "cloze_format": "The organelle that produces large quantities of ATP when both glucose and oxygen are available to the cell is the ___.", "normal_format": "Which of the following organelles produces large quantities of ATP when both glucose and oxygen are available to the cell?", "question_choices": [ "mitochondria", "peroxisomes", "lysosomes", "ER" ], "question_id": "fs-id1319018", "question_text": "Which of the following organelles produces large quantities of ATP when both glucose and oxygen are available to the cell?" }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 1, "ans_text": "a double cell membrane" }, "bloom": null, "hl_context": "A mitochondrion ( plural = mitochondria ) is a membranous , bean-shaped organelle that is the “ energy transformer ” of the cell . <hl> Mitochondria consist of an outer lipid bilayer membrane as well as an additional inner lipid bilayer membrane ( Figure 3.16 ) . <hl> The inner membrane is highly folded into winding structures with a great deal of surface area , called cristae . It is along this inner membrane that a series of proteins , enzymes , and other molecules perform the biochemical reactions of cellular respiration . These reactions convert energy stored in nutrient molecules ( such as glucose ) into adenosine triphosphate ( ATP ) , which provides usable cellular energy to the cell . Cells use ATP constantly , and so the mitochondria are constantly at work . Oxygen molecules are required during cellular respiration , which is why you must constantly breathe it in . One of the organ systems in the body that uses huge amounts of ATP is the muscular system because ATP is required to sustain muscle contraction . As a result , muscle cells are packed full of mitochondria . Nerve cells also need large quantities of ATP to run their sodium-potassium pumps . Therefore , an individual neuron will be loaded with over a thousand mitochondria . On the other hand , a bone cell , which is not nearly as metabolically-active , might only have a couple hundred mitochondria .", "hl_sentences": "Mitochondria consist of an outer lipid bilayer membrane as well as an additional inner lipid bilayer membrane ( Figure 3.16 ) .", "question": { "cloze_format": "The nucleus and mitochondria share ___ .", "normal_format": "The nucleus and mitochondria share which of the following features?", "question_choices": [ "protein-lined membrane pores", "a double cell membrane", "the synthesis of ribosomes", "the production of cellular energy" ], "question_id": "fs-id1613843", "question_text": "The nucleus and mitochondria share which of the following features?" }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 2, "ans_text": "ribosomes" }, "bloom": null, "hl_context": "Inside the nuclear envelope is a gel-like nucleoplasm with solutes that include the building blocks of nucleic acids . There also can be a dark-staining mass often visible under a simple light microscope , called a nucleolus ( plural = nucleoli ) . <hl> The nucleolus is a region of the nucleus that is responsible for manufacturing the RNA necessary for construction of ribosomes . <hl> <hl> Once synthesized , newly made ribosomal subunits exit the cell ’ s nucleus through the nuclear pores . <hl> The genetic instructions that are used to build and maintain an organism are arranged in an orderly manner in strands of DNA . Within the nucleus are threads of chromatin composed of DNA and associated proteins ( Figure 3.22 ) . Along the chromatin threads , the DNA is wrapped around a set of histone proteins . A nucleosome is a single , wrapped DNA-histone complex . Multiple nucleosomes along the entire molecule of DNA appear like a beaded necklace , in which the string is the DNA and the beads are the associated histones . When a cell is in the process of division , the chromatin condenses into chromosomes , so that the DNA can be safely transported to the “ daughter cells . ” The chromosome is composed of DNA and proteins ; it is the condensed form of chromatin . It is estimated that humans have almost 22,000 genes distributed on 46 chromosomes .", "hl_sentences": "The nucleolus is a region of the nucleus that is responsible for manufacturing the RNA necessary for construction of ribosomes . Once synthesized , newly made ribosomal subunits exit the cell ’ s nucleus through the nuclear pores .", "question": { "cloze_format": "The structure that could be found within the nucleolus is the ___ .", "normal_format": "Which of the following structures could be found within the nucleolus?", "question_choices": [ "chromatin", "histones", "ribosomes", "nucleosomes" ], "question_id": "fs-id1966803", "question_text": "Which of the following structures could be found within the nucleolus?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 2, "ans_text": "CGAATATA" }, "bloom": "3", "hl_context": "A DNA molecule is made of two strands that “ complement ” each other in the sense that the molecules that compose the strands fit together and bind to each other , creating a double-stranded molecule that looks much like a long , twisted ladder . This double helix can be constructed easily because the two strands are antiparallel , meaning the two strands run in opposite directions . Each side rail of the DNA ladder is composed of alternating sugar and phosphate groups ( Figure 3.23 ) . The two sides of the ladder are not identical , but are complementary . These two backbones are bonded to each other across pairs of protruding bases , each bonded pair forming one “ rung , ” or cross member . The four DNA bases are adenine ( A ) , thymine ( T ) , cytosine ( C ) , and guanine ( G ) . Because of their shape and charge , the two bases that compose a pair always bond together . <hl> Adenine always binds with thymine , and cytosine always binds with guanine . <hl> The particular sequence of bases along the DNA molecule determines the genetic code . Therefore , if the two complementary strands of DNA were pulled apart , you could infer the order of the bases in one strand from the bases in the other , complementary strand . For example , if one strand has a region with the sequence AGTGCCT , then the sequence of the complementary strand would be TCACGGA . DNA replication is the copying of DNA that occurs before cell division can take place . After a great deal of debate and experimentation , the general method of DNA replication was deduced in 1958 by two scientists in California , Matthew Meselson and Franklin Stahl . This method is illustrated in Figure 3.24 and described below .", "hl_sentences": "Adenine always binds with thymine , and cytosine always binds with guanine .", "question": { "cloze_format": "The sequence on a DNA molecule that would be complementary to GCTTATAT is ___.", "normal_format": "Which of the following sequences on a DNA molecule would be complementary to GCTTATAT?", "question_choices": [ "TAGGCGCG", "ATCCGCGC", "CGAATATA", "TGCCTCTC" ], "question_id": "fs-id14398440", "question_text": "Which of the following sequences on a DNA molecule would be complementary to GCTTATAT?" }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 0, "ans_text": "DNA, nucleosome, chromatin, chromosome" }, "bloom": "3", "hl_context": "Inside the nuclear envelope is a gel-like nucleoplasm with solutes that include the building blocks of nucleic acids . There also can be a dark-staining mass often visible under a simple light microscope , called a nucleolus ( plural = nucleoli ) . The nucleolus is a region of the nucleus that is responsible for manufacturing the RNA necessary for construction of ribosomes . Once synthesized , newly made ribosomal subunits exit the cell ’ s nucleus through the nuclear pores . The genetic instructions that are used to build and maintain an organism are arranged in an orderly manner in strands of DNA . <hl> Within the nucleus are threads of chromatin composed of DNA and associated proteins ( Figure 3.22 ) . <hl> <hl> Along the chromatin threads , the DNA is wrapped around a set of histone proteins . <hl> <hl> A nucleosome is a single , wrapped DNA-histone complex . <hl> <hl> Multiple nucleosomes along the entire molecule of DNA appear like a beaded necklace , in which the string is the DNA and the beads are the associated histones . <hl> <hl> When a cell is in the process of division , the chromatin condenses into chromosomes , so that the DNA can be safely transported to the “ daughter cells . ” The chromosome is composed of DNA and proteins ; it is the condensed form of chromatin . <hl> It is estimated that humans have almost 22,000 genes distributed on 46 chromosomes .", "hl_sentences": "Within the nucleus are threads of chromatin composed of DNA and associated proteins ( Figure 3.22 ) . Along the chromatin threads , the DNA is wrapped around a set of histone proteins . A nucleosome is a single , wrapped DNA-histone complex . Multiple nucleosomes along the entire molecule of DNA appear like a beaded necklace , in which the string is the DNA and the beads are the associated histones . When a cell is in the process of division , the chromatin condenses into chromosomes , so that the DNA can be safely transported to the “ daughter cells . ” The chromosome is composed of DNA and proteins ; it is the condensed form of chromatin .", "question": { "cloze_format": "The structures ___ are in order from least to most complex organization.", "normal_format": "What is the correct order from least to most complex organization in chromatin, nucleosome, DNA and chromosome structures?", "question_choices": [ "DNA, nucleosome, chromatin, chromosome", "nucleosome, DNA, chromosome, chromatin", "DNA, chromatin, nucleosome, chromosome", "nucleosome, chromatin, DNA, chromosome" ], "question_id": "fs-id1070949", "question_text": "Place the following structures in order from least to most complex organization: chromatin, nucleosome, DNA, chromosome" }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 1, "ans_text": "attaching complementary nucleotides to the template strand" }, "bloom": "1", "hl_context": "Stage 2 : Elongation . Transcription starts when RNA polymerase unwinds the DNA segment . <hl> One strand , referred to as the coding strand , becomes the template with the genes to be coded . <hl> <hl> The polymerase then aligns the correct nucleic acid ( A , C , G , or U ) with its complementary base on the coding strand of DNA . <hl> RNA polymerase is an enzyme that adds new nucleotides to a growing strand of RNA . This process builds a strand of mRNA . Stage 2 : Elongation . <hl> Each strand becomes a template along which a new complementary strand is built . <hl> DNA polymerase brings in the correct bases to complement the template strand , synthesizing a new strand base by base . A DNA polymerase is an enzyme that adds free nucleotides to the end of a chain of DNA , making a new double strand . This growing strand continues to be built until it has fully complemented the template strand .", "hl_sentences": "One strand , referred to as the coding strand , becomes the template with the genes to be coded . The polymerase then aligns the correct nucleic acid ( A , C , G , or U ) with its complementary base on the coding strand of DNA . Each strand becomes a template along which a new complementary strand is built .", "question": { "cloze_format": "___ is part of the elongation step of DNA synthesis.", "normal_format": "Which of the following is part of the elongation step of DNA synthesis?", "question_choices": [ "pulling apart the two DNA strands", "attaching complementary nucleotides to the template strand", "untwisting the DNA helix", "none of the above" ], "question_id": "fs-id1259347", "question_text": "Which of the following is part of the elongation step of DNA synthesis?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 2, "ans_text": "DNA contains alternating sugar-phosphate molecules whereas RNA does not contain sugars" }, "bloom": null, "hl_context": "There are several different types of RNA , each having different functions in the cell . The structure of RNA is similar to DNA with a few small exceptions . <hl> For one thing , unlike DNA , most types of RNA , including mRNA , are single-stranded and contain no complementary strand . <hl> <hl> Second , the ribose sugar in RNA contains an additional oxygen atom compared with DNA . <hl> <hl> Finally , instead of the base thymine , RNA contains the base uracil . <hl> This means that adenine will always pair up with uracil during the protein synthesis process . A DNA molecule is made of two strands that “ complement ” each other in the sense that the molecules that compose the strands fit together and bind to each other , creating a double-stranded molecule that looks much like a long , twisted ladder . This double helix can be constructed easily because the two strands are antiparallel , meaning the two strands run in opposite directions . <hl> Each side rail of the DNA ladder is composed of alternating sugar and phosphate groups ( Figure 3.23 ) . <hl> The two sides of the ladder are not identical , but are complementary . These two backbones are bonded to each other across pairs of protruding bases , each bonded pair forming one “ rung , ” or cross member . The four DNA bases are adenine ( A ) , thymine ( T ) , cytosine ( C ) , and guanine ( G ) . Because of their shape and charge , the two bases that compose a pair always bond together . Adenine always binds with thymine , and cytosine always binds with guanine . The particular sequence of bases along the DNA molecule determines the genetic code . Therefore , if the two complementary strands of DNA were pulled apart , you could infer the order of the bases in one strand from the bases in the other , complementary strand . For example , if one strand has a region with the sequence AGTGCCT , then the sequence of the complementary strand would be TCACGGA . DNA replication is the copying of DNA that occurs before cell division can take place . After a great deal of debate and experimentation , the general method of DNA replication was deduced in 1958 by two scientists in California , Matthew Meselson and Franklin Stahl . This method is illustrated in Figure 3.24 and described below .", "hl_sentences": "For one thing , unlike DNA , most types of RNA , including mRNA , are single-stranded and contain no complementary strand . Second , the ribose sugar in RNA contains an additional oxygen atom compared with DNA . Finally , instead of the base thymine , RNA contains the base uracil . Each side rail of the DNA ladder is composed of alternating sugar and phosphate groups ( Figure 3.23 ) .", "question": { "cloze_format": "The difference between DNA and RNA includes all of the following cases, except if ___.", "normal_format": "Which of the following is not a difference between DNA and RNA?", "question_choices": [ "DNA contains thymine whereas RNA contains uracil", "DNA contains deoxyribose and RNA contains ribose", "DNA contains alternating sugar-phosphate molecules whereas RNA does not contain sugars", "RNA is single stranded and DNA is double stranded" ], "question_id": "fs-id1506288", "question_text": "Which of the following is not a difference between DNA and RNA?" }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 0, "ans_text": "nucleus; cytoplasm" }, "bloom": null, "hl_context": "Before the mRNA molecule leaves the nucleus and proceeds to protein synthesis , it is modified in a number of ways . For this reason , it is often called a pre-mRNA at this stage . For example , your DNA , and thus complementary mRNA , contains long regions called non-coding regions that do not code for amino acids . Their function is still a mystery , but the process called splicing removes these non-coding regions from the pre-mRNA transcript ( Figure 3.27 ) . A spliceosome — a structure composed of various proteins and other molecules — attaches to the mRNA and “ splices ” or cuts out the non-coding regions . The removed segment of the transcript is called an intron . The remaining exons are pasted together . An exon is a segment of RNA that remains after splicing . Interestingly , some introns that are removed from mRNA are not always non-coding . When different coding regions of mRNA are spliced out , different variations of the protein will eventually result , with differences in structure and function . This process results in a much larger variety of possible proteins and protein functions . <hl> When the mRNA transcript is ready , it travels out of the nucleus and into the cytoplasm . <hl>", "hl_sentences": "When the mRNA transcript is ready , it travels out of the nucleus and into the cytoplasm .", "question": { "cloze_format": "Transcription and translation take place in the ________ and ________, respectively.", "normal_format": "Where do transcription and translation take place, respectively?", "question_choices": [ "nucleus; cytoplasm", "nucleolus; nucleus", "nucleolus; cytoplasm", "cytoplasm; nucleus" ], "question_id": "fs-id2433737", "question_text": "Transcription and translation take place in the ________ and ________, respectively." }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 2, "ans_text": "3" }, "bloom": "3", "hl_context": "Remember that many of a cell ’ s ribosomes are found associated with the rough ER , and carry out the synthesis of proteins destined for the Golgi apparatus . Ribosomal RNA ( rRNA ) is a type of RNA that , together with proteins , composes the structure of the ribosome . Ribosomes exist in the cytoplasm as two distinct components , a small and a large subunit . When an mRNA molecule is ready to be translated , the two subunits come together and attach to the mRNA . The ribosome provides a substrate for translation , bringing together and aligning the mRNA molecule with the molecular “ translators ” that must decipher its code . The other major requirement for protein synthesis is the translator molecules that physically “ read ” the mRNA codons . Transfer RNA ( tRNA ) is a type of RNA that ferries the appropriate corresponding amino acids to the ribosome , and attaches each new amino acid to the last , building the polypeptide chain one-by-one . Thus tRNA transfers specific amino acids from the cytoplasm to a growing polypeptide . The tRNA molecules must be able to recognize the codons on mRNA and match them with the correct amino acid . The tRNA is modified for this function . On one end of its structure is a binding site for a specific amino acid . On the other end is a base sequence that matches the codon specifying its particular amino acid . <hl> This sequence of three bases on the tRNA molecule is called an anticodon . <hl> For example , a tRNA responsible for shuttling the amino acid glycine contains a binding site for glycine on one end . On the other end it contains an anticodon that complements the glycine codon ( GGA is a codon for glycine , and so the tRNAs anticodon would read CCU ) . Equipped with its particular cargo and matching anticodon , a tRNA molecule can read its recognized mRNA codon and bring the corresponding amino acid to the growing chain ( Figure 3.28 ) .", "hl_sentences": "This sequence of three bases on the tRNA molecule is called an anticodon .", "question": { "cloze_format": "The number of “letters” of an RNA molecule, in sequence, that it takes to provide the code for a single amino acid is ___ .", "normal_format": "How many “letters” of an RNA molecule, in sequence, does it take to provide the code for a single amino acid?", "question_choices": [ "1", "2", "3", "4" ], "question_id": "fs-id2256955", "question_text": "How many “letters” of an RNA molecule, in sequence, does it take to provide the code for a single amino acid?" }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 1, "ans_text": "the ribosome" }, "bloom": null, "hl_context": "Much like the processes of DNA replication and transcription , translation consists of three main stages : initiation , elongation , and termination . Initiation takes place with the binding of a ribosome to an mRNA transcript . The elongation stage involves the recognition of a tRNA anticodon with the next mRNA codon in the sequence . <hl> Once the anticodon and codon sequences are bound ( remember , they are complementary base pairs ) , the tRNA presents its amino acid cargo and the growing polypeptide strand is attached to this next amino acid . <hl> This attachment takes place with the assistance of various enzymes and requires energy . <hl> The tRNA molecule then releases the mRNA strand , the mRNA strand shifts one codon over in the ribosome , and the next appropriate tRNA arrives with its matching anticodon . <hl> <hl> This process continues until the final codon on the mRNA is reached which provides a “ stop ” message that signals termination of translation and triggers the release of the complete , newly synthesized protein . <hl> Thus , a gene within the DNA molecule is transcribed into mRNA , which is then translated into a protein product ( Figure 3.29 ) . Remember that many of a cell ’ s ribosomes are found associated with the rough ER , and carry out the synthesis of proteins destined for the Golgi apparatus . Ribosomal RNA ( rRNA ) is a type of RNA that , together with proteins , composes the structure of the ribosome . Ribosomes exist in the cytoplasm as two distinct components , a small and a large subunit . When an mRNA molecule is ready to be translated , the two subunits come together and attach to the mRNA . The ribosome provides a substrate for translation , bringing together and aligning the mRNA molecule with the molecular “ translators ” that must decipher its code . The other major requirement for protein synthesis is the translator molecules that physically “ read ” the mRNA codons . <hl> Transfer RNA ( tRNA ) is a type of RNA that ferries the appropriate corresponding amino acids to the ribosome , and attaches each new amino acid to the last , building the polypeptide chain one-by-one . <hl> Thus tRNA transfers specific amino acids from the cytoplasm to a growing polypeptide . The tRNA molecules must be able to recognize the codons on mRNA and match them with the correct amino acid . The tRNA is modified for this function . On one end of its structure is a binding site for a specific amino acid . On the other end is a base sequence that matches the codon specifying its particular amino acid . This sequence of three bases on the tRNA molecule is called an anticodon . For example , a tRNA responsible for shuttling the amino acid glycine contains a binding site for glycine on one end . On the other end it contains an anticodon that complements the glycine codon ( GGA is a codon for glycine , and so the tRNAs anticodon would read CCU ) . Equipped with its particular cargo and matching anticodon , a tRNA molecule can read its recognized mRNA codon and bring the corresponding amino acid to the growing chain ( Figure 3.28 ) . Before the mRNA molecule leaves the nucleus and proceeds to protein synthesis , it is modified in a number of ways . For this reason , it is often called a pre-mRNA at this stage . For example , your DNA , and thus complementary mRNA , contains long regions called non-coding regions that do not code for amino acids . Their function is still a mystery , but the process called splicing removes these non-coding regions from the pre-mRNA transcript ( Figure 3.27 ) . <hl> A spliceosome — a structure composed of various proteins and other molecules — attaches to the mRNA and “ splices ” or cuts out the non-coding regions . <hl> <hl> The removed segment of the transcript is called an intron . <hl> <hl> The remaining exons are pasted together . <hl> An exon is a segment of RNA that remains after splicing . Interestingly , some introns that are removed from mRNA are not always non-coding . When different coding regions of mRNA are spliced out , different variations of the protein will eventually result , with differences in structure and function . This process results in a much larger variety of possible proteins and protein functions . When the mRNA transcript is ready , it travels out of the nucleus and into the cytoplasm . <hl> DNA is housed within the nucleus , and protein synthesis takes place in the cytoplasm , thus there must be some sort of intermediate messenger that leaves the nucleus and manages protein synthesis . <hl> This intermediate messenger is messenger RNA ( mRNA ) , a single-stranded nucleic acid that carries a copy of the genetic code for a single gene out of the nucleus and into the cytoplasm where it is used to produce proteins .", "hl_sentences": "Once the anticodon and codon sequences are bound ( remember , they are complementary base pairs ) , the tRNA presents its amino acid cargo and the growing polypeptide strand is attached to this next amino acid . The tRNA molecule then releases the mRNA strand , the mRNA strand shifts one codon over in the ribosome , and the next appropriate tRNA arrives with its matching anticodon . This process continues until the final codon on the mRNA is reached which provides a “ stop ” message that signals termination of translation and triggers the release of the complete , newly synthesized protein . Transfer RNA ( tRNA ) is a type of RNA that ferries the appropriate corresponding amino acids to the ribosome , and attaches each new amino acid to the last , building the polypeptide chain one-by-one . A spliceosome — a structure composed of various proteins and other molecules — attaches to the mRNA and “ splices ” or cuts out the non-coding regions . The removed segment of the transcript is called an intron . The remaining exons are pasted together . DNA is housed within the nucleus , and protein synthesis takes place in the cytoplasm , thus there must be some sort of intermediate messenger that leaves the nucleus and manages protein synthesis .", "question": { "cloze_format": "___ is not made out of RNA.", "normal_format": "Which of the following is not made out of RNA?", "question_choices": [ "the carriers that shuffle amino acids to a growing polypeptide strand", "the ribosome", "the messenger molecule that provides the code for protein synthesis", "the intron" ], "question_id": "fs-id1087021", "question_text": "Which of the following is not made out of RNA?" }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 1, "ans_text": "G1" }, "bloom": "1", "hl_context": "<hl> A cell grows and carries out all normal metabolic functions and processes in a period called G 1 ( Figure 3.30 ) . <hl> <hl> G 1 phase ( gap 1 phase ) is the first gap , or growth phase in the cell cycle . <hl> For cells that will divide again , G 1 is followed by replication of the DNA , during the S phase . The S phase ( synthesis phase ) is period during which a cell replicates its DNA .", "hl_sentences": "A cell grows and carries out all normal metabolic functions and processes in a period called G 1 ( Figure 3.30 ) . G 1 phase ( gap 1 phase ) is the first gap , or growth phase in the cell cycle .", "question": { "cloze_format": "The ___ phase is characterized by preparation for DNA synthesis.", "normal_format": "Which of the following phases is characterized by preparation for DNA synthesis?", "question_choices": [ "G0", "G1", "G2", "S" ], "question_id": "fs-id1312469", "question_text": "Which of the following phases is characterized by preparation for DNA synthesis?" }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 3, "ans_text": "any of the above" }, "bloom": "2", "hl_context": "These two contrasting classes of genes , proto-oncogenes and tumor suppressor genes , are like the accelerator and brake pedal of the cell ’ s own “ cruise control system , ” respectively . Under normal conditions , these stop and go signals are maintained in a homeostatic balance . <hl> Generally speaking , there are two ways that the cell ’ s cruise control can lose control : a malfunctioning ( overactive ) accelerator , or a malfunctioning ( underactive ) brake . <hl> <hl> When compromised through a mutation , or otherwise altered , proto-oncogenes can be converted to oncogenes , which produce oncoproteins that push a cell forward in its cycle and stimulate cell division even when it is undesirable to do so . <hl> For example , a cell that should be programmed to self-destruct ( a process called apoptosis ) due to extensive DNA damage might instead be triggered to proliferate by an oncoprotein . <hl> On the other hand , a dysfunctional tumor suppressor gene may fail to provide the cell with a necessary stop signal , also resulting in unwanted cell division and proliferation . <hl>", "hl_sentences": "Generally speaking , there are two ways that the cell ’ s cruise control can lose control : a malfunctioning ( overactive ) accelerator , or a malfunctioning ( underactive ) brake . When compromised through a mutation , or otherwise altered , proto-oncogenes can be converted to oncogenes , which produce oncoproteins that push a cell forward in its cycle and stimulate cell division even when it is undesirable to do so . On the other hand , a dysfunctional tumor suppressor gene may fail to provide the cell with a necessary stop signal , also resulting in unwanted cell division and proliferation .", "question": { "cloze_format": "A mutation in the gene for a cyclin protein might result in ___.", "normal_format": "A mutation in the gene for a cyclin protein might result in which of the following?", "question_choices": [ "a cell with additional genetic material than normal", "cancer", "a cell with less genetic material than normal", "any of the above" ], "question_id": "fs-id1486401", "question_text": "A mutation in the gene for a cyclin protein might result in which of the following?" }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 1, "ans_text": "stop certain cells from dividing" }, "bloom": "1", "hl_context": "<hl> A delicate homeostatic balance between the many proto-oncogenes and tumor suppressor genes delicately controls the cell cycle and ensures that only healthy cells replicate . <hl> <hl> Therefore , a disruption of this homeostatic balance can cause aberrant cell division and cancerous growths . <hl> In addition to cyclins , a class of proteins that are encoded by genes called proto-oncogenes provide important signals that regulate the cell cycle and move it forward . Examples of proto-oncogene products include cell-surface receptors for growth factors , or cell-signaling molecules , two classes of molecules that can promote DNA replication and cell division . In contrast , a second class of genes known as tumor suppressor genes sends stop signals during a cell cycle . <hl> For example , certain protein products of tumor suppressor genes signal potential problems with the DNA and thus stop the cell from dividing , while other proteins signal the cell to die if it is damaged beyond repair . <hl> Some tumor suppressor proteins also signal a sufficient surrounding cellular density , which indicates that the cell need not presently divide . The latter function is uniquely important in preventing tumor growth : normal cells exhibit a phenomenon called “ contact inhibition ; ” thus , extensive cellular contact with neighboring cells causes a signal that stops further cell division .", "hl_sentences": "A delicate homeostatic balance between the many proto-oncogenes and tumor suppressor genes delicately controls the cell cycle and ensures that only healthy cells replicate . Therefore , a disruption of this homeostatic balance can cause aberrant cell division and cancerous growths . For example , certain protein products of tumor suppressor genes signal potential problems with the DNA and thus stop the cell from dividing , while other proteins signal the cell to die if it is damaged beyond repair .", "question": { "cloze_format": "A primary function of tumor suppressor genes is to ___ .", "normal_format": "What is a primary function of tumor suppressor genes?", "question_choices": [ "stop all cells from dividing", "stop certain cells from dividing", "help oncogenes produce oncoproteins", "allow the cell to skip certain phases of the cell cycle" ], "question_id": "fs-id1211344", "question_text": "What is a primary function of tumor suppressor genes?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 2, "ans_text": "hematopoietic" }, "bloom": null, "hl_context": "A multipotent stem cell has the potential to differentiate into different types of cells within a given cell lineage or small number of lineages , such as a red blood cell or white blood cell . Finally , multipotent cells can become further specialized oligopotent cells . An oligopotent stem cell is limited to becoming one of a few different cell types . In contrast , a unipotent cell is fully specialized and can only reproduce to generate more of its own specific cell type . Stem cells are unique in that they can also continually divide and regenerate new stem cells instead of further specializing . There are different stem cells present at different stages of a human ’ s life . They include the embryonic stem cells of the embryo , fetal stem cells of the fetus , and adult stem cells in the adult . One type of adult stem cell is the epithelial stem cell , which gives rise to the keratinocytes in the multiple layers of epithelial cells in the epidermis of skin . <hl> Adult bone marrow has three distinct types of stem cells : hematopoietic stem cells , which give rise to red blood cells , white blood cells , and platelets ( Figure 3.34 ); endothelial stem cells , which give rise to the endothelial cell types that line blood and lymph vessels ; and mesenchymal stem cells , which give rise to the different types of muscle cells . <hl>", "hl_sentences": "Adult bone marrow has three distinct types of stem cells : hematopoietic stem cells , which give rise to red blood cells , white blood cells , and platelets ( Figure 3.34 ); endothelial stem cells , which give rise to the endothelial cell types that line blood and lymph vessels ; and mesenchymal stem cells , which give rise to the different types of muscle cells .", "question": { "cloze_format": "___ is the type of stem cell that gives rise to red and white blood cells.", "normal_format": "Which type of stem cell gives rise to red and white blood cells?", "question_choices": [ "endothelial", "epithelial", "hematopoietic", "mesenchymal" ], "question_id": "fs-id1497003", "question_text": "Which type of stem cell gives rise to red and white blood cells?" }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 2, "ans_text": "cells from the umbilical cord and from baby teeth" }, "bloom": null, "hl_context": "The mechanisms that induce a non-differentiated cell to become a specialized cell are poorly understood . In a laboratory setting , it is possible to induce stem cells to differentiate into specialized cells by changing the physical and chemical conditions of growth . Several sources of stem cells are used experimentally and are classified according to their origin and potential for differentiation . Human embryonic stem cells ( hESCs ) are extracted from embryos and are pluripotent . <hl> The adult stem cells that are present in many organs and differentiated tissues , such as bone marrow and skin , are multipotent , being limited in differentiation to the types of cells found in those tissues . <hl> <hl> The stem cells isolated from umbilical cord blood are also multipotent , as are cells from deciduous teeth ( baby teeth ) . <hl> Researchers have recently developed induced pluripotent stem cells ( iPSCs ) from mouse and human adult stem cells . These cells are genetically reprogrammed multipotent adult cells that function like embryonic stem cells ; they are capable of generating cells characteristic of all three germ layers .", "hl_sentences": "The adult stem cells that are present in many organs and differentiated tissues , such as bone marrow and skin , are multipotent , being limited in differentiation to the types of cells found in those tissues . The stem cells isolated from umbilical cord blood are also multipotent , as are cells from deciduous teeth ( baby teeth ) .", "question": { "cloze_format": "The multipotent stem cells from children that are sometimes banked by parents are the ___ .", "normal_format": "What multipotent stem cells from children sometimes banked by parents?", "question_choices": [ "fetal stem cells", "embryonic stem cells", "cells from the umbilical cord and from baby teeth", "hematopoietic stem cells from red and white blood cells" ], "question_id": "fs-id1526011", "question_text": "What multipotent stem cells from children sometimes banked by parents?" }, "references_are_paraphrase": 0 } ]
3
3.1 The Cell Membrane Learning Objectives By the end of this section, you will be able to: Describe the molecular components that make up the cell membrane Explain the major features and properties of the cell membrane Differentiate between materials that can and cannot diffuse through the lipid bilayer Compare and contrast different types of passive transport with active transport, providing examples of each Despite differences in structure and function, all living cells in multicellular organisms have a surrounding cell membrane. As the outer layer of your skin separates your body from its environment, the cell membrane (also known as the plasma membrane) separates the inner contents of a cell from its exterior environment. This cell membrane provides a protective barrier around the cell and regulates which materials can pass in or out. Structure and Composition of the Cell Membrane The cell membrane is an extremely pliable structure composed primarily of back-to-back phospholipids (a “bilayer”). Cholesterol is also present, which contributes to the fluidity of the membrane, and there are various proteins embedded within the membrane that have a variety of functions. A single phospholipid molecule has a phosphate group on one end, called the “head,” and two side-by-side chains of fatty acids that make up the lipid tails ( Figure 3.2 ). The phosphate group is negatively charged, making the head polar and hydrophilic—or “water loving.” A hydrophilic molecule (or region of a molecule) is one that is attracted to water. The phosphate heads are thus attracted to the water molecules of both the extracellular and intracellular environments. The lipid tails, on the other hand, are uncharged, or nonpolar, and are hydrophobic—or “water fearing.” A hydrophobic molecule (or region of a molecule) repels and is repelled by water. Some lipid tails consist of saturated fatty acids and some contain unsaturated fatty acids. This combination adds to the fluidity of the tails that are constantly in motion. Phospholipids are thus amphipathic molecules. An amphipathic molecule is one that contains both a hydrophilic and a hydrophobic region. In fact, soap works to remove oil and grease stains because it has amphipathic properties. The hydrophilic portion can dissolve in water while the hydrophobic portion can trap grease in micelles that then can be washed away. The cell membrane consists of two adjacent layers of phospholipids. The lipid tails of one layer face the lipid tails of the other layer, meeting at the interface of the two layers. The phospholipid heads face outward, one layer exposed to the interior of the cell and one layer exposed to the exterior ( Figure 3.3 ). Because the phosphate groups are polar and hydrophilic, they are attracted to water in the intracellular fluid. Intracellular fluid (ICF) is the fluid interior of the cell. The phosphate groups are also attracted to the extracellular fluid. Extracellular fluid (ECF) is the fluid environment outside the enclosure of the cell membrane. Interstitial fluid (IF) is the term given to extracellular fluid not contained within blood vessels. Because the lipid tails are hydrophobic, they meet in the inner region of the membrane, excluding watery intracellular and extracellular fluid from this space. The cell membrane has many proteins, as well as other lipids (such as cholesterol), that are associated with the phospholipid bilayer. An important feature of the membrane is that it remains fluid; the lipids and proteins in the cell membrane are not rigidly locked in place. Membrane Proteins The lipid bilayer forms the basis of the cell membrane, but it is peppered throughout with various proteins. Two different types of proteins that are commonly associated with the cell membrane are the integral proteins and peripheral protein ( Figure 3.4 ). As its name suggests, an integral protein is a protein that is embedded in the membrane. A channel protein is an example of an integral protein that selectively allows particular materials, such as certain ions, to pass into or out of the cell. Another important group of integral proteins are cell recognition proteins, which serve to mark a cell’s identity so that it can be recognized by other cells. A receptor is a type of recognition protein that can selectively bind a specific molecule outside the cell, and this binding induces a chemical reaction within the cell. A ligand is the specific molecule that binds to and activates a receptor. Some integral proteins serve dual roles as both a receptor and an ion channel. One example of a receptor-ligand interaction is the receptors on nerve cells that bind neurotransmitters, such as dopamine. When a dopamine molecule binds to a dopamine receptor protein, a channel within the transmembrane protein opens to allow certain ions to flow into the cell. Some integral membrane proteins are glycoproteins. A glycoprotein is a protein that has carbohydrate molecules attached, which extend into the extracellular matrix. The attached carbohydrate tags on glycoproteins aid in cell recognition. The carbohydrates that extend from membrane proteins and even from some membrane lipids collectively form the glycocalyx. The glycocalyx is a fuzzy-appearing coating around the cell formed from glycoproteins and other carbohydrates attached to the cell membrane. The glycocalyx can have various roles. For example, it may have molecules that allow the cell to bind to another cell, it may contain receptors for hormones, or it might have enzymes to break down nutrients. The glycocalyces found in a person’s body are products of that person’s genetic makeup. They give each of the individual’s trillions of cells the “identity” of belonging in the person’s body. This identity is the primary way that a person’s immune defense cells “know” not to attack the person’s own body cells, but it also is the reason organs donated by another person might be rejected. Peripheral proteins are typically found on the inner or outer surface of the lipid bilayer but can also be attached to the internal or external surface of an integral protein. These proteins typically perform a specific function for the cell. Some peripheral proteins on the surface of intestinal cells, for example, act as digestive enzymes to break down nutrients to sizes that can pass through the cells and into the bloodstream. Transport across the Cell Membrane One of the great wonders of the cell membrane is its ability to regulate the concentration of substances inside the cell. These substances include ions such as Ca ++ , Na + , K + , and Cl – ; nutrients including sugars, fatty acids, and amino acids; and waste products, particularly carbon dioxide (CO 2 ), which must leave the cell. The membrane’s lipid bilayer structure provides the first level of control. The phospholipids are tightly packed together, and the membrane has a hydrophobic interior. This structure causes the membrane to be selectively permeable. A membrane that has selective permeability allows only substances meeting certain criteria to pass through it unaided. In the case of the cell membrane, only relatively small, nonpolar materials can move through the lipid bilayer (remember, the lipid tails of the membrane are nonpolar). Some examples of these are other lipids, oxygen and carbon dioxide gases, and alcohol. However, water-soluble materials—like glucose, amino acids, and electrolytes—need some assistance to cross the membrane because they are repelled by the hydrophobic tails of the phospholipid bilayer. All substances that move through the membrane do so by one of two general methods, which are categorized based on whether or not energy is required. Passive transport is the movement of substances across the membrane without the expenditure of cellular energy. In contrast, active transport is the movement of substances across the membrane using energy from adenosine triphosphate (ATP). Passive Transport In order to understand how substances move passively across a cell membrane, it is necessary to understand concentration gradients and diffusion. A concentration gradient is the difference in concentration of a substance across a space. Molecules (or ions) will spread/diffuse from where they are more concentrated to where they are less concentrated until they are equally distributed in that space. (When molecules move in this way, they are said to move down their concentration gradient.) Diffusion is the movement of particles from an area of higher concentration to an area of lower concentration. A couple of common examples will help to illustrate this concept. Imagine being inside a closed bathroom. If a bottle of perfume were sprayed, the scent molecules would naturally diffuse from the spot where they left the bottle to all corners of the bathroom, and this diffusion would go on until no more concentration gradient remains. Another example is a spoonful of sugar placed in a cup of tea. Eventually the sugar will diffuse throughout the tea until no concentration gradient remains. In both cases, if the room is warmer or the tea hotter, diffusion occurs even faster as the molecules are bumping into each other and spreading out faster than at cooler temperatures. Having an internal body temperature around 98.6 ° F thus also aids in diffusion of particles within the body. Interactive Link Visit this link to see diffusion and how it is propelled by the kinetic energy of molecules in solution. How does temperature affect diffusion rate, and why? Whenever a substance exists in greater concentration on one side of a semipermeable membrane, such as the cell membranes, any substance that can move down its concentration gradient across the membrane will do so. Consider substances that can easily diffuse through the lipid bilayer of the cell membrane, such as the gases oxygen (O 2 ) and CO 2 . O 2 generally diffuses into cells because it is more concentrated outside of them, and CO 2 typically diffuses out of cells because it is more concentrated inside of them. Neither of these examples requires any energy on the part of the cell, and therefore they use passive transport to move across the membrane. Before moving on, you need to review the gases that can diffuse across a cell membrane. Because cells rapidly use up oxygen during metabolism, there is typically a lower concentration of O 2 inside the cell than outside. As a result, oxygen will diffuse from the interstitial fluid directly through the lipid bilayer of the membrane and into the cytoplasm within the cell. On the other hand, because cells produce CO 2 as a byproduct of metabolism, CO 2 concentrations rise within the cytoplasm; therefore, CO 2 will move from the cell through the lipid bilayer and into the interstitial fluid, where its concentration is lower. This mechanism of molecules moving across a cell membrane from the side where they are more concentrated to the side where they are less concentrated is a form of passive transport called simple diffusion ( Figure 3.5 ). Large polar or ionic molecules, which are hydrophilic, cannot easily cross the phospholipid bilayer. Very small polar molecules, such as water, can cross via simple diffusion due to their small size. Charged atoms or molecules of any size cannot cross the cell membrane via simple diffusion as the charges are repelled by the hydrophobic tails in the interior of the phospholipid bilayer. Solutes dissolved in water on either side of the cell membrane will tend to diffuse down their concentration gradients, but because most substances cannot pass freely through the lipid bilayer of the cell membrane, their movement is restricted to protein channels and specialized transport mechanisms in the membrane. Facilitated diffusion is the diffusion process used for those substances that cannot cross the lipid bilayer due to their size, charge, and/or polarity ( Figure 3.6 ). A common example of facilitated diffusion is the movement of glucose into the cell, where it is used to make ATP. Although glucose can be more concentrated outside of a cell, it cannot cross the lipid bilayer via simple diffusion because it is both large and polar. To resolve this, a specialized carrier protein called the glucose transporter will transfer glucose molecules into the cell to facilitate its inward diffusion. As an example, even though sodium ions (Na + ) are highly concentrated outside of cells, these electrolytes are charged and cannot pass through the nonpolar lipid bilayer of the membrane. Their diffusion is facilitated by membrane proteins that form sodium channels (or “pores”), so that Na + ions can move down their concentration gradient from outside the cells to inside the cells. There are many other solutes that must undergo facilitated diffusion to move into a cell, such as amino acids, or to move out of a cell, such as wastes. Because facilitated diffusion is a passive process, it does not require energy expenditure by the cell. Water also can move freely across the cell membrane of all cells, either through protein channels or by slipping between the lipid tails of the membrane itself. Osmosis is the diffusion of water through a semipermeable membrane ( Figure 3.7 ). The movement of water molecules is not itself regulated by some cells, so it is important that these cells are exposed to an environment in which the concentration of solutes outside of the cells (in the extracellular fluid) is equal to the concentration of solutes inside the cells (in the cytoplasm). Two solutions that have the same concentration of solutes are said to be isotonic (equal tension). When cells and their extracellular environments are isotonic, the concentration of water molecules is the same outside and inside the cells, and the cells maintain their normal shape (and function). Osmosis occurs when there is an imbalance of solutes outside of a cell versus inside the cell. A solution that has a higher concentration of solutes than another solution is said to be hypertonic , and water molecules tend to diffuse into a hypertonic solution ( Figure 3.8 ). Cells in a hypertonic solution will shrivel as water leaves the cell via osmosis. In contrast, a solution that has a lower concentration of solutes than another solution is said to be hypotonic , and water molecules tend to diffuse out of a hypotonic solution. Cells in a hypotonic solution will take on too much water and swell, with the risk of eventually bursting. A critical aspect of homeostasis in living things is to create an internal environment in which all of the body’s cells are in an isotonic solution. Various organ systems, particularly the kidneys, work to maintain this homeostasis. Another mechanism besides diffusion to passively transport materials between compartments is filtration. Unlike diffusion of a substance from where it is more concentrated to less concentrated, filtration uses a hydrostatic pressure gradient that pushes the fluid—and the solutes within it—from a higher pressure area to a lower pressure area. Filtration is an extremely important process in the body. For example, the circulatory system uses filtration to move plasma and substances across the endothelial lining of capillaries and into surrounding tissues, supplying cells with the nutrients. Filtration pressure in the kidneys provides the mechanism to remove wastes from the bloodstream. Active Transport For all of the transport methods described above, the cell expends no energy. Membrane proteins that aid in the passive transport of substances do so without the use of ATP. During active transport, ATP is required to move a substance across a membrane, often with the help of protein carriers, and usually against its concentration gradient. One of the most common types of active transport involves proteins that serve as pumps. The word “pump” probably conjures up thoughts of using energy to pump up the tire of a bicycle or a basketball. Similarly, energy from ATP is required for these membrane proteins to transport substances—molecules or ions—across the membrane, usually against their concentration gradients (from an area of low concentration to an area of high concentration). The sodium-potassium pump , which is also called Na + /K + ATPase, transports sodium out of a cell while moving potassium into the cell. The Na + /K + pump is an important ion pump found in the membranes of many types of cells. These pumps are particularly abundant in nerve cells, which are constantly pumping out sodium ions and pulling in potassium ions to maintain an electrical gradient across their cell membranes. An electrical gradient is a difference in electrical charge across a space. In the case of nerve cells, for example, the electrical gradient exists between the inside and outside of the cell, with the inside being negatively-charged (at around -70 mV) relative to the outside. The negative electrical gradient is maintained because each Na + /K + pump moves three Na + ions out of the cell and two K + ions into the cell for each ATP molecule that is used ( Figure 3.9 ). This process is so important for nerve cells that it accounts for the majority of their ATP usage. Active transport pumps can also work together with other active or passive transport systems to move substances across the membrane. For example, the sodium-potassium pump maintains a high concentration of sodium ions outside of the cell. Therefore, if the cell needs sodium ions, all it has to do is open a passive sodium channel, as the concentration gradient of the sodium ions will drive them to diffuse into the cell. In this way, the action of an active transport pump (the sodium-potassium pump) powers the passive transport of sodium ions by creating a concentration gradient. When active transport powers the transport of another substance in this way, it is called secondary active transport. Symporters are secondary active transporters that move two substances in the same direction. For example, the sodium-glucose symporter uses sodium ions to “pull” glucose molecules into the cell. Because cells store glucose for energy, glucose is typically at a higher concentration inside of the cell than outside. However, due to the action of the sodium-potassium pump, sodium ions will easily diffuse into the cell when the symporter is opened. The flood of sodium ions through the symporter provides the energy that allows glucose to move through the symporter and into the cell, against its concentration gradient. Conversely, antiporters are secondary active transport systems that transport substances in opposite directions. For example, the sodium-hydrogen ion antiporter uses the energy from the inward flood of sodium ions to move hydrogen ions (H+) out of the cell. The sodium-hydrogen antiporter is used to maintain the pH of the cell's interior. Other forms of active transport do not involve membrane carriers. Endocytosis (bringing “into the cell”) is the process of a cell ingesting material by enveloping it in a portion of its cell membrane, and then pinching off that portion of membrane ( Figure 3.10 ). Once pinched off, the portion of membrane and its contents becomes an independent, intracellular vesicle. A vesicle is a membranous sac—a spherical and hollow organelle bounded by a lipid bilayer membrane. Endocytosis often brings materials into the cell that must to be broken down or digested. Phagocytosis (“cell eating”) is the endocytosis of large particles. Many immune cells engage in phagocytosis of invading pathogens. Like little Pac-men, their job is to patrol body tissues for unwanted matter, such as invading bacterial cells, phagocytize them, and digest them. In contrast to phagocytosis, pinocytosis (“cell drinking”) brings fluid containing dissolved substances into a cell through membrane vesicles. Phagocytosis and pinocytosis take in large portions of extracellular material, and they are typically not highly selective in the substances they bring in. Cells regulate the endocytosis of specific substances via receptor-mediated endocytosis. Receptor-mediated endocytosis is endocytosis by a portion of the cell membrane that contains many receptors that are specific for a certain substance. Once the surface receptors have bound sufficient amounts of the specific substance (the receptor’s ligand), the cell will endocytose the part of the cell membrane containing the receptor-ligand complexes. Iron, a required component of hemoglobin, is endocytosed by red blood cells in this way. Iron is bound to a protein called transferrin in the blood. Specific transferrin receptors on red blood cell surfaces bind the iron-transferrin molecules, and the cell endocytoses the receptor-ligand complexes. In contrast with endocytosis, exocytosis (taking “out of the cell”) is the process of a cell exporting material using vesicular transport ( Figure 3.11 ). Many cells manufacture substances that must be secreted, like a factory manufacturing a product for export. These substances are typically packaged into membrane-bound vesicles within the cell. When the vesicle membrane fuses with the cell membrane, the vesicle releases it contents into the interstitial fluid. The vesicle membrane then becomes part of the cell membrane. Cells of the stomach and pancreas produce and secrete digestive enzymes through exocytosis ( Figure 3.12 ). Endocrine cells produce and secrete hormones that are sent throughout the body, and certain immune cells produce and secrete large amounts of histamine, a chemical important for immune responses. Interactive Link View the University of Michigan WebScope to explore the tissue sample in greater detail. Diseases of the... Cell: Cystic Fibrosis Cystic fibrosis (CF) affects approximately 30,000 people in the United States, with about 1,000 new cases reported each year. The genetic disease is most well known for its damage to the lungs, causing breathing difficulties and chronic lung infections, but it also affects the liver, pancreas, and intestines. Only about 50 years ago, the prognosis for children born with CF was very grim—a life expectancy rarely over 10 years. Today, with advances in medical treatment, many CF patients live into their 30s. The symptoms of CF result from a malfunctioning membrane ion channel called the cystic fibrosis transmembrane conductance regulator, or CFTR. In healthy people, the CFTR protein is an integral membrane protein that transports Cl – ions out of the cell. In a person who has CF, the gene for the CFTR is mutated, thus, the cell manufactures a defective channel protein that typically is not incorporated into the membrane, but is instead degraded by the cell. The CFTR requires ATP in order to function, making its Cl – transport a form of active transport. This characteristic puzzled researchers for a long time because the Cl – ions are actually flowing down their concentration gradient when transported out of cells. Active transport generally pumps ions against their concentration gradient, but the CFTR presents an exception to this rule. In normal lung tissue, the movement of Cl – out of the cell maintains a Cl – -rich, negatively charged environment immediately outside of the cell. This is particularly important in the epithelial lining of the respiratory system. Respiratory epithelial cells secrete mucus, which serves to trap dust, bacteria, and other debris. A cilium (plural = cilia) is one of the hair-like appendages found on certain cells. Cilia on the epithelial cells move the mucus and its trapped particles up the airways away from the lungs and toward the outside. In order to be effectively moved upward, the mucus cannot be too viscous; rather it must have a thin, watery consistency. The transport of Cl – and the maintenance of an electronegative environment outside of the cell attract positive ions such as Na + to the extracellular space. The accumulation of both Cl – and Na + ions in the extracellular space creates solute-rich mucus, which has a low concentration of water molecules. As a result, through osmosis, water moves from cells and extracellular matrix into the mucus, “thinning” it out. This is how, in a normal respiratory system, the mucus is kept sufficiently watered-down to be propelled out of the respiratory system. If the CFTR channel is absent, Cl – ions are not transported out of the cell in adequate numbers, thus preventing them from drawing positive ions. The absence of ions in the secreted mucus results in the lack of a normal water concentration gradient. Thus, there is no osmotic pressure pulling water into the mucus. The resulting mucus is thick and sticky, and the ciliated epithelia cannot effectively remove it from the respiratory system. Passageways in the lungs become blocked with mucus, along with the debris it carries. Bacterial infections occur more easily because bacterial cells are not effectively carried away from the lungs. 3.2 The Cytoplasm and Cellular Organelles Learning Objectives By the end of this section, you will be able to: Describe the structure and function of the cellular organelles associated with the endomembrane system, including the endoplasmic reticulum, Golgi apparatus, and lysosomes Describe the structure and function of mitochondria and peroxisomes Explain the three components of the cytoskeleton, including their composition and functions Now that you have learned that the cell membrane surrounds all cells, you can dive inside of a prototypical human cell to learn about its internal components and their functions. All living cells in multicellular organisms contain an internal cytoplasmic compartment, and a nucleus within the cytoplasm. Cytosol , the jelly-like substance within the cell, provides the fluid medium necessary for biochemical reactions. Eukaryotic cells, including all animal cells, also contain various cellular organelles. An organelle (“little organ”) is one of several different types of membrane-enclosed bodies in the cell, each performing a unique function. Just as the various bodily organs work together in harmony to perform all of a human’s functions, the many different cellular organelles work together to keep the cell healthy and performing all of its important functions. The organelles and cytosol, taken together, compose the cell’s cytoplasm . The nucleus is a cell’s central organelle, which contains the cell’s DNA ( Figure 3.13 ). Organelles of the Endomembrane System A set of three major organelles together form a system within the cell called the endomembrane system. These organelles work together to perform various cellular jobs, including the task of producing, packaging, and exporting certain cellular products. The organelles of the endomembrane system include the endoplasmic reticulum, Golgi apparatus, and vesicles. Endoplasmic Reticulum The endoplasmic reticulum (ER) is a system of channels that is continuous with the nuclear membrane (or “envelope”) covering the nucleus and composed of the same lipid bilayer material. The ER can be thought of as a series of winding thoroughfares similar to the waterway canals in Venice. The ER provides passages throughout much of the cell that function in transporting, synthesizing, and storing materials. The winding structure of the ER results in a large membranous surface area that supports its many functions ( Figure 3.14 ). Endoplasmic reticulum can exist in two forms: rough ER and smooth ER. These two types of ER perform some very different functions and can be found in very different amounts depending on the type of cell. Rough ER (RER) is so-called because its membrane is dotted with embedded granules—organelles called ribosomes, giving the RER a bumpy appearance. A ribosome is an organelle that serves as the site of protein synthesis. It is composed of two ribosomal RNA subunits that wrap around mRNA to start the process of translation, followed by protein synthesis. Smooth ER (SER) lacks these ribosomes. One of the main functions of the smooth ER is in the synthesis of lipids. The smooth ER synthesizes phospholipids, the main component of biological membranes, as well as steroid hormones. For this reason, cells that produce large quantities of such hormones, such as those of the female ovaries and male testes, contain large amounts of smooth ER. In addition to lipid synthesis, the smooth ER also sequesters (i.e., stores) and regulates the concentration of cellular Ca ++ , a function extremely important in cells of the nervous system where Ca ++ is the trigger for neurotransmitter release. The smooth ER additionally metabolizes some carbohydrates and performs a detoxification role, breaking down certain toxins. In contrast with the smooth ER, the primary job of the rough ER is the synthesis and modification of proteins destined for the cell membrane or for export from the cell. For this protein synthesis, many ribosomes attach to the ER (giving it the studded appearance of rough ER). Typically, a protein is synthesized within the ribosome and released inside the channel of the rough ER, where sugars can be added to it (by a process called glycosylation) before it is transported within a vesicle to the next stage in the packaging and shipping process: the Golgi apparatus. The Golgi Apparatus The Golgi apparatus is responsible for sorting, modifying, and shipping off the products that come from the rough ER, much like a post-office. The Golgi apparatus looks like stacked flattened discs, almost like stacks of oddly shaped pancakes. Like the ER, these discs are membranous. The Golgi apparatus has two distinct sides, each with a different role. One side of the apparatus receives products in vesicles. These products are sorted through the apparatus, and then they are released from the opposite side after being repackaged into new vesicles. If the product is to be exported from the cell, the vesicle migrates to the cell surface and fuses to the cell membrane, and the cargo is secreted ( Figure 3.15 ). Lysosomes Some of the protein products packaged by the Golgi include digestive enzymes that are meant to remain inside the cell for use in breaking down certain materials. The enzyme-containing vesicles released by the Golgi may form new lysosomes, or fuse with existing, lysosomes. A lysosome is an organelle that contains enzymes that break down and digest unneeded cellular components, such as a damaged organelle. (A lysosome is similar to a wrecking crew that takes down old and unsound buildings in a neighborhood.) Autophagy (“self-eating”) is the process of a cell digesting its own structures. Lysosomes are also important for breaking down foreign material. For example, when certain immune defense cells (white blood cells) phagocytize bacteria, the bacterial cell is transported into a lysosome and digested by the enzymes inside. As one might imagine, such phagocytic defense cells contain large numbers of lysosomes. Under certain circumstances, lysosomes perform a more grand and dire function. In the case of damaged or unhealthy cells, lysosomes can be triggered to open up and release their digestive enzymes into the cytoplasm of the cell, killing the cell. This “self-destruct” mechanism is called autolysis , and makes the process of cell death controlled (a mechanism called “apoptosis”). Interactive Link Watch this video to learn about the endomembrane system, which includes the rough and smooth ER and the Golgi body as well as lysosomes and vesicles. What is the primary role of the endomembrane system? Organelles for Energy Production and Detoxification In addition to the jobs performed by the endomembrane system, the cell has many other important functions. Just as you must consume nutrients to provide yourself with energy, so must each of your cells take in nutrients, some of which convert to chemical energy that can be used to power biochemical reactions. Another important function of the cell is detoxification. Humans take in all sorts of toxins from the environment and also produce harmful chemicals as byproducts of cellular processes. Cells called hepatocytes in the liver detoxify many of these toxins. Mitochondria A mitochondrion (plural = mitochondria) is a membranous, bean-shaped organelle that is the “energy transformer” of the cell. Mitochondria consist of an outer lipid bilayer membrane as well as an additional inner lipid bilayer membrane ( Figure 3.16 ). The inner membrane is highly folded into winding structures with a great deal of surface area, called cristae. It is along this inner membrane that a series of proteins, enzymes, and other molecules perform the biochemical reactions of cellular respiration. These reactions convert energy stored in nutrient molecules (such as glucose) into adenosine triphosphate (ATP), which provides usable cellular energy to the cell. Cells use ATP constantly, and so the mitochondria are constantly at work. Oxygen molecules are required during cellular respiration, which is why you must constantly breathe it in. One of the organ systems in the body that uses huge amounts of ATP is the muscular system because ATP is required to sustain muscle contraction. As a result, muscle cells are packed full of mitochondria. Nerve cells also need large quantities of ATP to run their sodium-potassium pumps. Therefore, an individual neuron will be loaded with over a thousand mitochondria. On the other hand, a bone cell, which is not nearly as metabolically-active, might only have a couple hundred mitochondria. Peroxisomes Like lysosomes, a peroxisome is a membrane-bound cellular organelle that contains mostly enzymes ( Figure 3.17 ). Peroxisomes perform a couple of different functions, including lipid metabolism and chemical detoxification. In contrast to the digestive enzymes found in lysosomes, the enzymes within peroxisomes serve to transfer hydrogen atoms from various molecules to oxygen, producing hydrogen peroxide (H 2 O 2 ). In this way, peroxisomes neutralize poisons such as alcohol. In order to appreciate the importance of peroxisomes, it is necessary to understand the concept of reactive oxygen species. Reactive oxygen species (ROS) such as peroxides and free radicals are the highly reactive products of many normal cellular processes, including the mitochondrial reactions that produce ATP and oxygen metabolism. Examples of ROS include the hydroxyl radical OH, H 2 O 2 , and superoxide ( O 2 − O 2 − ). Some ROS are important for certain cellular functions, such as cell signaling processes and immune responses against foreign substances. Free radicals are reactive because they contain free unpaired electrons; they can easily oxidize other molecules throughout the cell, causing cellular damage and even cell death. Free radicals are thought to play a role in many destructive processes in the body, from cancer to coronary artery disease. Peroxisomes, on the other hand, oversee reactions that neutralize free radicals. Peroxisomes produce large amounts of the toxic H 2 O 2 in the process, but peroxisomes contain enzymes that convert H 2 O 2 into water and oxygen. These byproducts are safely released into the cytoplasm. Like miniature sewage treatment plants, peroxisomes neutralize harmful toxins so that they do not wreak havoc in the cells. The liver is the organ primarily responsible for detoxifying the blood before it travels throughout the body, and liver cells contain an exceptionally high number of peroxisomes. Defense mechanisms such as detoxification within the peroxisome and certain cellular antioxidants serve to neutralize many of these molecules. Some vitamins and other substances, found primarily in fruits and vegetables, have antioxidant properties. Antioxidants work by being oxidized themselves, halting the destructive reaction cascades initiated by the free radicals. Sometimes though, ROS accumulate beyond the capacity of such defenses. Oxidative stress is the term used to describe damage to cellular components caused by ROS. Due to their characteristic unpaired electrons, ROS can set off chain reactions where they remove electrons from other molecules, which then become oxidized and reactive, and do the same to other molecules, causing a chain reaction. ROS can cause permanent damage to cellular lipids, proteins, carbohydrates, and nucleic acids. Damaged DNA can lead to genetic mutations and even cancer. A mutation is a change in the nucleotide sequence in a gene within a cell’s DNA, potentially altering the protein coded by that gene. Other diseases believed to be triggered or exacerbated by ROS include Alzheimer’s disease, cardiovascular diseases, diabetes, Parkinson’s disease, arthritis, Huntington’s disease, and schizophrenia, among many others. It is noteworthy that these diseases are largely age-related. Many scientists believe that oxidative stress is a major contributor to the aging process. Aging and the... Cell: The Free Radical Theory The free radical theory on aging was originally proposed in the 1950s, and still remains under debate. Generally speaking, the free radical theory of aging suggests that accumulated cellular damage from oxidative stress contributes to the physiological and anatomical effects of aging. There are two significantly different versions of this theory: one states that the aging process itself is a result of oxidative damage, and the other states that oxidative damage causes age-related disease and disorders. The latter version of the theory is more widely accepted than the former. However, many lines of evidence suggest that oxidative damage does contribute to the aging process. Research has shown that reducing oxidative damage can result in a longer lifespan in certain organisms such as yeast, worms, and fruit flies. Conversely, increasing oxidative damage can shorten the lifespan of mice and worms. Interestingly, a manipulation called calorie-restriction (moderately restricting the caloric intake) has been shown to increase life span in some laboratory animals. It is believed that this increase is at least in part due to a reduction of oxidative stress. However, a long-term study of primates with calorie-restriction showed no increase in their lifespan. A great deal of additional research will be required to better understand the link between reactive oxygen species and aging. The Cytoskeleton Much like the bony skeleton structurally supports the human body, the cytoskeleton helps the cells to maintain their structural integrity. The cytoskeleton is a group of fibrous proteins that provide structural support for cells, but this is only one of the functions of the cytoskeleton. Cytoskeletal components are also critical for cell motility, cell reproduction, and transportation of substances within the cell. The cytoskeleton forms a complex thread-like network throughout the cell consisting of three different kinds of protein-based filaments: microfilaments, intermediate filaments, and microtubules ( Figure 3.18 ). The thickest of the three is the microtubule , a structural filament composed of subunits of a protein called tubulin. Microtubules maintain cell shape and structure, help resist compression of the cell, and play a role in positioning the organelles within the cell. Microtubules also make up two types of cellular appendages important for motion: cilia and flagella. Cilia are found on many cells of the body, including the epithelial cells that line the airways of the respiratory system. Cilia move rhythmically; they beat constantly, moving waste materials such as dust, mucus, and bacteria upward through the airways, away from the lungs and toward the mouth. Beating cilia on cells in the female fallopian tubes move egg cells from the ovary towards the uterus. A flagellum (plural = flagella) is an appendage larger than a cilium and specialized for cell locomotion. The only flagellated cell in humans is the sperm cell that must propel itself towards female egg cells. A very important function of microtubules is to set the paths (somewhat like railroad tracks) along which the genetic material can be pulled (a process requiring ATP) during cell division, so that each new daughter cell receives the appropriate set of chromosomes. Two short, identical microtubule structures called centrioles are found near the nucleus of cells. A centriole can serve as the cellular origin point for microtubules extending outward as cilia or flagella or can assist with the separation of DNA during cell division. Microtubules grow out from the centrioles by adding more tubulin subunits, like adding additional links to a chain. In contrast with microtubules, the microfilament is a thinner type of cytoskeletal filament (see Figure 3.18 b ). Actin, a protein that forms chains, is the primary component of these microfilaments. Actin fibers, twisted chains of actin filaments, constitute a large component of muscle tissue and, along with the protein myosin, are responsible for muscle contraction. Like microtubules, actin filaments are long chains of single subunits (called actin subunits). In muscle cells, these long actin strands, called thin filaments, are “pulled” by thick filaments of the myosin protein to contract the cell. Actin also has an important role during cell division. When a cell is about to split in half during cell division, actin filaments work with myosin to create a cleavage furrow that eventually splits the cell down the middle, forming two new cells from the original cell. The final cytoskeletal filament is the intermediate filament. As its name would suggest, an intermediate filament is a filament intermediate in thickness between the microtubules and microfilaments (see Figure 3.18 c ). Intermediate filaments are made up of long fibrous subunits of a protein called keratin that are wound together like the threads that compose a rope. Intermediate filaments, in concert with the microtubules, are important for maintaining cell shape and structure. Unlike the microtubules, which resist compression, intermediate filaments resist tension—the forces that pull apart cells. There are many cases in which cells are prone to tension, such as when epithelial cells of the skin are compressed, tugging them in different directions. Intermediate filaments help anchor organelles together within a cell and also link cells to other cells by forming special cell-to-cell junctions. 3.3 The Nucleus and DNA Replication Learning Objectives By the end of this section, you will be able to: Describe the structure and features of the nuclear membrane List the contents of the nucleus Explain the organization of the DNA molecule within the nucleus Describe the process of DNA replication The nucleus is the largest and most prominent of a cell’s organelles ( Figure 3.19 ). The nucleus is generally considered the control center of the cell because it stores all of the genetic instructions for manufacturing proteins. Interestingly, some cells in the body, such as muscle cells, contain more than one nucleus ( Figure 3.20 ), which is known as multinucleated. Other cells, such as mammalian red blood cells (RBCs), do not contain nuclei at all. RBCs eject their nuclei as they mature, making space for the large numbers of hemoglobin molecules that carry oxygen throughout the body ( Figure 3.21 ). Without nuclei, the life span of RBCs is short, and so the body must produce new ones constantly. Interactive Link View the University of Michigan WebScope to explore the tissue sample in greater detail. Interactive Link View the University of Michigan WebScope to explore the tissue sample in greater detail. Inside the nucleus lies the blueprint that dictates everything a cell will do and all of the products it will make. This information is stored within DNA. The nucleus sends “commands” to the cell via molecular messengers that translate the information from DNA. Each cell in your body (with the exception of germ cells) contains the complete set of your DNA. When a cell divides, the DNA must be duplicated so that the each new cell receives a full complement of DNA. The following section will explore the structure of the nucleus and its contents, as well as the process of DNA replication. Organization of the Nucleus and Its DNA Like most other cellular organelles, the nucleus is surrounded by a membrane called the nuclear envelope . This membranous covering consists of two adjacent lipid bilayers with a thin fluid space in between them. Spanning these two bilayers are nuclear pores. A nuclear pore is a tiny passageway for the passage of proteins, RNA, and solutes between the nucleus and the cytoplasm. Proteins called pore complexes lining the nuclear pores regulate the passage of materials into and out of the nucleus. Inside the nuclear envelope is a gel-like nucleoplasm with solutes that include the building blocks of nucleic acids. There also can be a dark-staining mass often visible under a simple light microscope, called a nucleolus (plural = nucleoli). The nucleolus is a region of the nucleus that is responsible for manufacturing the RNA necessary for construction of ribosomes. Once synthesized, newly made ribosomal subunits exit the cell’s nucleus through the nuclear pores. The genetic instructions that are used to build and maintain an organism are arranged in an orderly manner in strands of DNA. Within the nucleus are threads of chromatin composed of DNA and associated proteins ( Figure 3.22 ). Along the chromatin threads, the DNA is wrapped around a set of histone proteins. A nucleosome is a single, wrapped DNA-histone complex. Multiple nucleosomes along the entire molecule of DNA appear like a beaded necklace, in which the string is the DNA and the beads are the associated histones. When a cell is in the process of division, the chromatin condenses into chromosomes, so that the DNA can be safely transported to the “daughter cells.” The chromosome is composed of DNA and proteins; it is the condensed form of chromatin. It is estimated that humans have almost 22,000 genes distributed on 46 chromosomes. DNA Replication In order for an organism to grow, develop, and maintain its health, cells must reproduce themselves by dividing to produce two new daughter cells, each with the full complement of DNA as found in the original cell. Billions of new cells are produced in an adult human every day. Only very few cell types in the body do not divide, including nerve cells, skeletal muscle fibers, and cardiac muscle cells. The division time of different cell types varies. Epithelial cells of the skin and gastrointestinal lining, for instance, divide very frequently to replace those that are constantly being rubbed off of the surface by friction. A DNA molecule is made of two strands that “complement” each other in the sense that the molecules that compose the strands fit together and bind to each other, creating a double-stranded molecule that looks much like a long, twisted ladder. This double helix can be constructed easily because the two strands are antiparallel, meaning the two strands run in opposite directions. Each side rail of the DNA ladder is composed of alternating sugar and phosphate groups ( Figure 3.23 ). The two sides of the ladder are not identical, but are complementary. These two backbones are bonded to each other across pairs of protruding bases, each bonded pair forming one “rung,” or cross member. The four DNA bases are adenine (A), thymine (T), cytosine (C), and guanine (G). Because of their shape and charge, the two bases that compose a pair always bond together. Adenine always binds with thymine, and cytosine always binds with guanine. The particular sequence of bases along the DNA molecule determines the genetic code. Therefore, if the two complementary strands of DNA were pulled apart, you could infer the order of the bases in one strand from the bases in the other, complementary strand. For example, if one strand has a region with the sequence AGTGCCT, then the sequence of the complementary strand would be TCACGGA. DNA replication is the copying of DNA that occurs before cell division can take place. After a great deal of debate and experimentation, the general method of DNA replication was deduced in 1958 by two scientists in California, Matthew Meselson and Franklin Stahl. This method is illustrated in Figure 3.24 and described below. Stage 1: Initiation. The two complementary strands are separated, much like unzipping a zipper. Special enzymes, including helicase , untwist and separate the two strands of DNA. Stage 2: Elongation. Each strand becomes a template along which a new complementary strand is built. DNA polymerase brings in the correct bases to complement the template strand, synthesizing a new strand base by base. A DNA polymerase is an enzyme that adds free nucleotides to the end of a chain of DNA, making a new double strand. This growing strand continues to be built until it has fully complemented the template strand. Stage 3: Termination. Once the two original strands are bound to their own, finished, complementary strands, DNA replication is stopped and the two new identical DNA molecules are complete. Each new DNA molecule contains one strand from the original molecule and one newly synthesized strand. The term for this mode of replication is “semiconservative,” because half of the original DNA molecule is conserved in each new DNA molecule. This process continues until the cell’s entire genome , the entire complement of an organism’s DNA, is replicated. As you might imagine, it is very important that DNA replication take place precisely so that new cells in the body contain the exact same genetic material as their parent cells. Mistakes made during DNA replication, such as the accidental addition of an inappropriate nucleotide, have the potential to render a gene dysfunctional or useless. Fortunately, there are mechanisms in place to minimize such mistakes. A DNA proofreading process enlists the help of special enzymes that scan the newly synthesized molecule for mistakes and corrects them. Once the process of DNA replication is complete, the cell is ready to divide. You will explore the process of cell division later in the chapter. Interactive Link Watch this video to learn about DNA replication. DNA replication proceeds simultaneously at several sites on the same molecule. What separates the base pair at the start of DNA replication? 3.4 Protein Synthesis Learning Objectives By the end of this section, you will be able to: Explain how the genetic code stored within DNA determines the protein that will form Describe the process of transcription Describe the process of translation Discuss the function of ribosomes It was mentioned earlier that DNA provides a “blueprint” for the cell structure and physiology. This refers to the fact that DNA contains the information necessary for the cell to build one very important type of molecule: the protein. Most structural components of the cell are made up, at least in part, by proteins and virtually all the functions that a cell carries out are completed with the help of proteins. One of the most important classes of proteins is enzymes, which help speed up necessary biochemical reactions that take place inside the cell. Some of these critical biochemical reactions include building larger molecules from smaller components (such as occurs during DNA replication or synthesis of microtubules) and breaking down larger molecules into smaller components (such as when harvesting chemical energy from nutrient molecules). Whatever the cellular process may be, it is almost sure to involve proteins. Just as the cell’s genome describes its full complement of DNA, a cell’s proteome is its full complement of proteins. Protein synthesis begins with genes. A gene is a functional segment of DNA that provides the genetic information necessary to build a protein. Each particular gene provides the code necessary to construct a particular protein. Gene expression , which transforms the information coded in a gene to a final gene product, ultimately dictates the structure and function of a cell by determining which proteins are made. The interpretation of genes works in the following way. Recall that proteins are polymers, or chains, of many amino acid building blocks. The sequence of bases in a gene (that is, its sequence of A, T, C, G nucleotides) translates to an amino acid sequence. A triplet is a section of three DNA bases in a row that codes for a specific amino acid. Similar to the way in which the three-letter code d-o-g signals the image of a dog, the three-letter DNA base code signals the use of a particular amino acid. For example, the DNA triplet CAC (cytosine, adenine, and cytosine) specifies the amino acid valine. Therefore, a gene, which is composed of multiple triplets in a unique sequence, provides the code to build an entire protein, with multiple amino acids in the proper sequence ( Figure 3.25 ). The mechanism by which cells turn the DNA code into a protein product is a two-step process, with an RNA molecule as the intermediate. From DNA to RNA: Transcription DNA is housed within the nucleus, and protein synthesis takes place in the cytoplasm, thus there must be some sort of intermediate messenger that leaves the nucleus and manages protein synthesis. This intermediate messenger is messenger RNA (mRNA) , a single-stranded nucleic acid that carries a copy of the genetic code for a single gene out of the nucleus and into the cytoplasm where it is used to produce proteins. There are several different types of RNA, each having different functions in the cell. The structure of RNA is similar to DNA with a few small exceptions. For one thing, unlike DNA, most types of RNA, including mRNA, are single-stranded and contain no complementary strand. Second, the ribose sugar in RNA contains an additional oxygen atom compared with DNA. Finally, instead of the base thymine, RNA contains the base uracil. This means that adenine will always pair up with uracil during the protein synthesis process. Gene expression begins with the process called transcription , which is the synthesis of a strand of mRNA that is complementary to the gene of interest. This process is called transcription because the mRNA is like a transcript, or copy, of the gene’s DNA code. Transcription begins in a fashion somewhat like DNA replication, in that a region of DNA unwinds and the two strands separate, however, only that small portion of the DNA will be split apart. The triplets within the gene on this section of the DNA molecule are used as the template to transcribe the complementary strand of RNA ( Figure 3.26 ). A codon is a three-base sequence of mRNA, so-called because they directly encode amino acids. Like DNA replication, there are three stages to transcription: initiation, elongation, and termination. Stage 1: Initiation. A region at the beginning of the gene called a promoter —a particular sequence of nucleotides—triggers the start of transcription. Stage 2: Elongation. Transcription starts when RNA polymerase unwinds the DNA segment. One strand, referred to as the coding strand, becomes the template with the genes to be coded. The polymerase then aligns the correct nucleic acid (A, C, G, or U) with its complementary base on the coding strand of DNA. RNA polymerase is an enzyme that adds new nucleotides to a growing strand of RNA. This process builds a strand of mRNA. Stage 3: Termination. At the end of the gene, a sequence of nucleotides called the terminator sequence causes the new RNA to fold up on itself. This fold causes the RNA to separate from the gene and from RNA polymerase, ending transcription. Before the mRNA molecule leaves the nucleus and proceeds to protein synthesis, it is modified in a number of ways. For this reason, it is often called a pre-mRNA at this stage. For example, your DNA, and thus complementary mRNA, contains long regions called non-coding regions that do not code for amino acids. Their function is still a mystery, but the process called splicing removes these non-coding regions from the pre-mRNA transcript ( Figure 3.27 ). A spliceosome —a structure composed of various proteins and other molecules—attaches to the mRNA and “splices” or cuts out the non-coding regions. The removed segment of the transcript is called an intron . The remaining exons are pasted together. An exon is a segment of RNA that remains after splicing. Interestingly, some introns that are removed from mRNA are not always non-coding. When different coding regions of mRNA are spliced out, different variations of the protein will eventually result, with differences in structure and function. This process results in a much larger variety of possible proteins and protein functions. When the mRNA transcript is ready, it travels out of the nucleus and into the cytoplasm. From RNA to Protein: Translation Like translating a book from one language into another, the codons on a strand of mRNA must be translated into the amino acid alphabet of proteins. Translation is the process of synthesizing a chain of amino acids called a polypeptide . Translation requires two major aids: first, a “translator,” the molecule that will conduct the translation, and second, a substrate on which the mRNA strand is translated into a new protein, like the translator’s “desk.” Both of these requirements are fulfilled by other types of RNA. The substrate on which translation takes place is the ribosome. Remember that many of a cell’s ribosomes are found associated with the rough ER, and carry out the synthesis of proteins destined for the Golgi apparatus. Ribosomal RNA (rRNA) is a type of RNA that, together with proteins, composes the structure of the ribosome. Ribosomes exist in the cytoplasm as two distinct components, a small and a large subunit. When an mRNA molecule is ready to be translated, the two subunits come together and attach to the mRNA. The ribosome provides a substrate for translation, bringing together and aligning the mRNA molecule with the molecular “translators” that must decipher its code. The other major requirement for protein synthesis is the translator molecules that physically “read” the mRNA codons. Transfer RNA (tRNA) is a type of RNA that ferries the appropriate corresponding amino acids to the ribosome, and attaches each new amino acid to the last, building the polypeptide chain one-by-one. Thus tRNA transfers specific amino acids from the cytoplasm to a growing polypeptide. The tRNA molecules must be able to recognize the codons on mRNA and match them with the correct amino acid. The tRNA is modified for this function. On one end of its structure is a binding site for a specific amino acid. On the other end is a base sequence that matches the codon specifying its particular amino acid. This sequence of three bases on the tRNA molecule is called an anticodon . For example, a tRNA responsible for shuttling the amino acid glycine contains a binding site for glycine on one end. On the other end it contains an anticodon that complements the glycine codon (GGA is a codon for glycine, and so the tRNAs anticodon would read CCU). Equipped with its particular cargo and matching anticodon, a tRNA molecule can read its recognized mRNA codon and bring the corresponding amino acid to the growing chain ( Figure 3.28 ). Much like the processes of DNA replication and transcription, translation consists of three main stages: initiation, elongation, and termination. Initiation takes place with the binding of a ribosome to an mRNA transcript. The elongation stage involves the recognition of a tRNA anticodon with the next mRNA codon in the sequence. Once the anticodon and codon sequences are bound (remember, they are complementary base pairs), the tRNA presents its amino acid cargo and the growing polypeptide strand is attached to this next amino acid. This attachment takes place with the assistance of various enzymes and requires energy. The tRNA molecule then releases the mRNA strand, the mRNA strand shifts one codon over in the ribosome, and the next appropriate tRNA arrives with its matching anticodon. This process continues until the final codon on the mRNA is reached which provides a “stop” message that signals termination of translation and triggers the release of the complete, newly synthesized protein. Thus, a gene within the DNA molecule is transcribed into mRNA, which is then translated into a protein product ( Figure 3.29 ). Commonly, an mRNA transcription will be translated simultaneously by several adjacent ribosomes. This increases the efficiency of protein synthesis. A single ribosome might translate an mRNA molecule in approximately one minute; so multiple ribosomes aboard a single transcript could produce multiple times the number of the same protein in the same minute. A polyribosome is a string of ribosomes translating a single mRNA strand. Interactive Link Watch this video to learn about ribosomes. The ribosome binds to the mRNA molecule to start translation of its code into a protein. What happens to the small and large ribosomal subunits at the end of translation? 3.5 Cell Growth and Division Learning Objectives By the end of this section, you will be able to: Describe the stages of the cell cycle Discuss how the cell cycle is regulated Describe the implications of losing control over the cell cycle Describe the stages of mitosis and cytokinesis, in order So far in this chapter, you have read numerous times of the importance and prevalence of cell division. While there are a few cells in the body that do not undergo cell division (such as gametes, red blood cells, most neurons, and some muscle cells), most somatic cells divide regularly. A somatic cell is a general term for a body cell, and all human cells, except for the cells that produce eggs and sperm (which are referred to as germ cells), are somatic cells. Somatic cells contain two copies of each of their chromosomes (one copy received from each parent). A homologous pair of chromosomes is the two copies of a single chromosome found in each somatic cell. The human is a diploid organism, having 23 homologous pairs of chromosomes in each of the somatic cells. The condition of having pairs of chromosomes is known as diploidy. Cells in the body replace themselves over the lifetime of a person. For example, the cells lining the gastrointestinal tract must be frequently replaced when constantly “worn off” by the movement of food through the gut. But what triggers a cell to divide, and how does it prepare for and complete cell division? The cell cycle is the sequence of events in the life of the cell from the moment it is created at the end of a previous cycle of cell division until it then divides itself, generating two new cells. The Cell Cycle One “turn” or cycle of the cell cycle consists of two general phases: interphase, followed by mitosis and cytokinesis. Interphase is the period of the cell cycle during which the cell is not dividing. The majority of cells are in interphase most of the time. Mitosis is the division of genetic material, during which the cell nucleus breaks down and two new, fully functional, nuclei are formed. Cytokinesis divides the cytoplasm into two distinctive cells. Interphase A cell grows and carries out all normal metabolic functions and processes in a period called G 1 ( Figure 3.30 ). G 1 phase (gap 1 phase) is the first gap, or growth phase in the cell cycle. For cells that will divide again, G 1 is followed by replication of the DNA, during the S phase. The S phase (synthesis phase) is period during which a cell replicates its DNA. After the synthesis phase, the cell proceeds through the G 2 phase. The G 2 phase is a second gap phase, during which the cell continues to grow and makes the necessary preparations for mitosis. Between G 1 , S, and G 2 phases, cells will vary the most in their duration of the G1 phase. It is here that a cell might spend a couple of hours, or many days. The S phase typically lasts between 8-10 hours and the G 2 phase approximately 5 hours. In contrast to these phases, the G 0 phase is a resting phase of the cell cycle. Cells that have temporarily stopped dividing and are resting (a common condition) and cells that have permanently ceased dividing (like nerve cells) are said to be in G 0 . The Structure of Chromosomes Billions of cells in the human body divide every day. During the synthesis phase (S, for DNA synthesis) of interphase, the amount of DNA within the cell precisely doubles. Therefore, after DNA replication but before cell division, each cell actually contains two copies of each chromosome. Each copy of the chromosome is referred to as a sister chromatid and is physically bound to the other copy. The centromere is the structure that attaches one sister chromatid to another. Because a human cell has 46 chromosomes, during this phase, there are 92 chromatids (46 × 2) in the cell. Make sure not to confuse the concept of a pair of chromatids (one chromosome and its exact copy attached during mitosis) and a homologous pair of chromosomes (two paired chromosomes which were inherited separately, one from each parent) ( Figure 3.31 ). Mitosis and Cytokinesis The mitotic phase of the cell typically takes between 1 and 2 hours. During this phase, a cell undergoes two major processes. First, it completes mitosis, during which the contents of the nucleus are equitably pulled apart and distributed between its two halves. Cytokinesis then occurs, dividing the cytoplasm and cell body into two new cells. Mitosis is divided into four major stages that take place after interphase ( Figure 3.32 ) and in the following order: prophase, metaphase, anaphase, and telophase. The process is then followed by cytokinesis. Prophase is the first phase of mitosis, during which the loosely packed chromatin coils and condenses into visible chromosomes. During prophase, each chromosome becomes visible with its identical partner attached, forming the familiar X-shape of sister chromatids. The nucleolus disappears early during this phase, and the nuclear envelope also disintegrates. A major occurrence during prophase concerns a very important structure that contains the origin site for microtubule growth. Recall the cellular structures called centrioles that serve as origin points from which microtubules extend. These tiny structures also play a very important role during mitosis. A centrosome is a pair of centrioles together. The cell contains two centrosomes side-by-side, which begin to move apart during prophase. As the centrosomes migrate to two different sides of the cell, microtubules begin to extend from each like long fingers from two hands extending toward each other. The mitotic spindle is the structure composed of the centrosomes and their emerging microtubules. Near the end of prophase there is an invasion of the nuclear area by microtubules from the mitotic spindle. The nuclear membrane has disintegrated, and the microtubules attach themselves to the centromeres that adjoin pairs of sister chromatids. The kinetochore is a protein structure on the centromere that is the point of attachment between the mitotic spindle and the sister chromatids. This stage is referred to as late prophase or “prometaphase” to indicate the transition between prophase and metaphase. Metaphase is the second stage of mitosis. During this stage, the sister chromatids, with their attached microtubules, line up along a linear plane in the middle of the cell. A metaphase plate forms between the centrosomes that are now located at either end of the cell. The metaphase plate is the name for the plane through the center of the spindle on which the sister chromatids are positioned. The microtubules are now poised to pull apart the sister chromatids and bring one from each pair to each side of the cell. Anaphase is the third stage of mitosis. Anaphase takes place over a few minutes, when the pairs of sister chromatids are separated from one another, forming individual chromosomes once again. These chromosomes are pulled to opposite ends of the cell by their kinetochores, as the microtubules shorten. Each end of the cell receives one partner from each pair of sister chromatids, ensuring that the two new daughter cells will contain identical genetic material. Telophase is the final stage of mitosis. Telophase is characterized by the formation of two new daughter nuclei at either end of the dividing cell. These newly formed nuclei surround the genetic material, which uncoils such that the chromosomes return to loosely packed chromatin. Nucleoli also reappear within the new nuclei, and the mitotic spindle breaks apart, each new cell receiving its own complement of DNA, organelles, membranes, and centrioles. At this point, the cell is already beginning to split in half as cytokinesis begins. The cleavage furrow is a contractile band made up of microfilaments that forms around the midline of the cell during cytokinesis. (Recall that microfilaments consist of actin.) This contractile band squeezes the two cells apart until they finally separate. Two new cells are now formed. One of these cells (the “stem cell”) enters its own cell cycle; able to grow and divide again at some future time. The other cell transforms into the functional cell of the tissue, typically replacing an “old” cell there. Imagine a cell that completed mitosis but never underwent cytokinesis. In some cases, a cell may divide its genetic material and grow in size, but fail to undergo cytokinesis. This results in larger cells with more than one nucleus. Usually this is an unwanted aberration and can be a sign of cancerous cells. Cell Cycle Control A very elaborate and precise system of regulation controls direct the way cells proceed from one phase to the next in the cell cycle and begin mitosis. The control system involves molecules within the cell as well as external triggers. These internal and external control triggers provide “stop” and “advance” signals for the cell. Precise regulation of the cell cycle is critical for maintaining the health of an organism, and loss of cell cycle control can lead to cancer. Mechanisms of Cell Cycle Control As the cell proceeds through its cycle, each phase involves certain processes that must be completed before the cell should advance to the next phase. A checkpoint is a point in the cell cycle at which the cycle can be signaled to move forward or stopped. At each of these checkpoints, different varieties of molecules provide the stop or go signals, depending on certain conditions within the cell. A cyclin is one of the primary classes of cell cycle control molecules ( Figure 3.33 ). A cyclin-dependent kinase (CDK) is one of a group of molecules that work together with cyclins to determine progression past cell checkpoints. By interacting with many additional molecules, these triggers push the cell cycle forward unless prevented from doing so by “stop” signals, if for some reason the cell is not ready. At the G 1 checkpoint, the cell must be ready for DNA synthesis to occur. At the G 2 checkpoint the cell must be fully prepared for mitosis. Even during mitosis, a crucial stop and go checkpoint in metaphase ensures that the cell is fully prepared to complete cell division. The metaphase checkpoint ensures that all sister chromatids are properly attached to their respective microtubules and lined up at the metaphase plate before the signal is given to separate them during anaphase. The Cell Cycle Out of Control: Implications Most people understand that cancer or tumors are caused by abnormal cells that multiply continuously. If the abnormal cells continue to divide unstopped, they can damage the tissues around them, spread to other parts of the body, and eventually result in death. In healthy cells, the tight regulation mechanisms of the cell cycle prevent this from happening, while failures of cell cycle control can cause unwanted and excessive cell division. Failures of control may be caused by inherited genetic abnormalities that compromise the function of certain “stop” and “go” signals. Environmental insult that damages DNA can also cause dysfunction in those signals. Often, a combination of both genetic predisposition and environmental factors lead to cancer. The process of a cell escaping its normal control system and becoming cancerous may actually happen throughout the body quite frequently. Fortunately, certain cells of the immune system are capable of recognizing cells that have become cancerous and destroying them. However, in certain cases the cancerous cells remain undetected and continue to proliferate. If the resulting tumor does not pose a threat to surrounding tissues, it is said to be benign and can usually be easily removed. If capable of damage, the tumor is considered malignant and the patient is diagnosed with cancer. Homeostatic Imbalances Cancer Arises from Homeostatic Imbalances Cancer is an extremely complex condition, capable of arising from a wide variety of genetic and environmental causes. Typically, mutations or aberrations in a cell’s DNA that compromise normal cell cycle control systems lead to cancerous tumors. Cell cycle control is an example of a homeostatic mechanism that maintains proper cell function and health. While progressing through the phases of the cell cycle, a large variety of intracellular molecules provide stop and go signals to regulate movement forward to the next phase. These signals are maintained in an intricate balance so that the cell only proceeds to the next phase when it is ready. This homeostatic control of the cell cycle can be thought of like a car’s cruise control. Cruise control will continually apply just the right amount of acceleration to maintain a desired speed, unless the driver hits the brakes, in which case the car will slow down. Similarly, the cell includes molecular messengers, such as cyclins, that push the cell forward in its cycle. In addition to cyclins, a class of proteins that are encoded by genes called proto-oncogenes provide important signals that regulate the cell cycle and move it forward. Examples of proto-oncogene products include cell-surface receptors for growth factors, or cell-signaling molecules, two classes of molecules that can promote DNA replication and cell division. In contrast, a second class of genes known as tumor suppressor genes sends stop signals during a cell cycle. For example, certain protein products of tumor suppressor genes signal potential problems with the DNA and thus stop the cell from dividing, while other proteins signal the cell to die if it is damaged beyond repair. Some tumor suppressor proteins also signal a sufficient surrounding cellular density, which indicates that the cell need not presently divide. The latter function is uniquely important in preventing tumor growth: normal cells exhibit a phenomenon called “contact inhibition;” thus, extensive cellular contact with neighboring cells causes a signal that stops further cell division. These two contrasting classes of genes, proto-oncogenes and tumor suppressor genes, are like the accelerator and brake pedal of the cell’s own “cruise control system,” respectively. Under normal conditions, these stop and go signals are maintained in a homeostatic balance. Generally speaking, there are two ways that the cell’s cruise control can lose control: a malfunctioning (overactive) accelerator, or a malfunctioning (underactive) brake. When compromised through a mutation, or otherwise altered, proto-oncogenes can be converted to oncogenes, which produce oncoproteins that push a cell forward in its cycle and stimulate cell division even when it is undesirable to do so. For example, a cell that should be programmed to self-destruct (a process called apoptosis) due to extensive DNA damage might instead be triggered to proliferate by an oncoprotein. On the other hand, a dysfunctional tumor suppressor gene may fail to provide the cell with a necessary stop signal, also resulting in unwanted cell division and proliferation. A delicate homeostatic balance between the many proto-oncogenes and tumor suppressor genes delicately controls the cell cycle and ensures that only healthy cells replicate. Therefore, a disruption of this homeostatic balance can cause aberrant cell division and cancerous growths. Interactive Link Visit this link to learn about mitosis. Mitosis results in two identical diploid cells. What structures forms during prophase? 3.6 Cellular Differentiation Learning Objectives By the end of this section, you will be able to: Discuss how the generalized cells of a developing embryo or the stem cells of an adult organism become differentiated into specialized cells Distinguish between the categories of stem cells How does a complex organism such as a human develop from a single cell—a fertilized egg—into the vast array of cell types such as nerve cells, muscle cells, and epithelial cells that characterize the adult? Throughout development and adulthood, the process of cellular differentiation leads cells to assume their final morphology and physiology. Differentiation is the process by which unspecialized cells become specialized to carry out distinct functions. Stem Cells A stem cell is an unspecialized cell that can divide without limit as needed and can, under specific conditions, differentiate into specialized cells. Stem cells are divided into several categories according to their potential to differentiate. The first embryonic cells that arise from the division of the zygote are the ultimate stem cells; these stems cells are described as totipotent because they have the potential to differentiate into any of the cells needed to enable an organism to grow and develop. The embryonic cells that develop from totipotent stem cells and are precursors to the fundamental tissue layers of the embryo are classified as pluripotent. A pluripotent stem cell is one that has the potential to differentiate into any type of human tissue but cannot support the full development of an organism. These cells then become slightly more specialized, and are referred to as multipotent cells. A multipotent stem cell has the potential to differentiate into different types of cells within a given cell lineage or small number of lineages, such as a red blood cell or white blood cell. Finally, multipotent cells can become further specialized oligopotent cells. An oligopotent stem cell is limited to becoming one of a few different cell types. In contrast, a unipotent cell is fully specialized and can only reproduce to generate more of its own specific cell type. Stem cells are unique in that they can also continually divide and regenerate new stem cells instead of further specializing. There are different stem cells present at different stages of a human’s life. They include the embryonic stem cells of the embryo, fetal stem cells of the fetus, and adult stem cells in the adult. One type of adult stem cell is the epithelial stem cell, which gives rise to the keratinocytes in the multiple layers of epithelial cells in the epidermis of skin. Adult bone marrow has three distinct types of stem cells: hematopoietic stem cells, which give rise to red blood cells, white blood cells, and platelets ( Figure 3.34 ); endothelial stem cells, which give rise to the endothelial cell types that line blood and lymph vessels; and mesenchymal stem cells, which give rise to the different types of muscle cells. Differentiation When a cell differentiates (becomes more specialized), it may undertake major changes in its size, shape, metabolic activity, and overall function. Because all cells in the body, beginning with the fertilized egg, contain the same DNA, how do the different cell types come to be so different? The answer is analogous to a movie script. The different actors in a movie all read from the same script, however, they are each only reading their own part of the script. Similarly, all cells contain the same full complement of DNA, but each type of cell only “reads” the portions of DNA that are relevant to its own function. In biology, this is referred to as the unique genetic expression of each cell. In order for a cell to differentiate into its specialized form and function, it need only manipulate those genes (and thus those proteins) that will be expressed, and not those that will remain silent. The primary mechanism by which genes are turned “on” or “off” is through transcription factors. A transcription factor is one of a class of proteins that bind to specific genes on the DNA molecule and either promote or inhibit their transcription ( Figure 3.35 ). Everyday Connection Stem Cell Research Stem cell research aims to find ways to use stem cells to regenerate and repair cellular damage. Over time, most adult cells undergo the wear and tear of aging and lose their ability to divide and repair themselves. Stem cells do not display a particular morphology or function. Adult stem cells, which exist as a small subset of cells in most tissues, keep dividing and can differentiate into a number of specialized cells generally formed by that tissue. These cells enable the body to renew and repair body tissues. The mechanisms that induce a non-differentiated cell to become a specialized cell are poorly understood. In a laboratory setting, it is possible to induce stem cells to differentiate into specialized cells by changing the physical and chemical conditions of growth. Several sources of stem cells are used experimentally and are classified according to their origin and potential for differentiation. Human embryonic stem cells (hESCs) are extracted from embryos and are pluripotent. The adult stem cells that are present in many organs and differentiated tissues, such as bone marrow and skin, are multipotent, being limited in differentiation to the types of cells found in those tissues. The stem cells isolated from umbilical cord blood are also multipotent, as are cells from deciduous teeth (baby teeth). Researchers have recently developed induced pluripotent stem cells (iPSCs) from mouse and human adult stem cells. These cells are genetically reprogrammed multipotent adult cells that function like embryonic stem cells; they are capable of generating cells characteristic of all three germ layers. Because of their capacity to divide and differentiate into specialized cells, stem cells offer a potential treatment for diseases such as diabetes and heart disease ( Figure 3.36 ). Cell-based therapy refers to treatment in which stem cells induced to differentiate in a growth dish are injected into a patient to repair damaged or destroyed cells or tissues. Many obstacles must be overcome for the application of cell-based therapy. Although embryonic stem cells have a nearly unlimited range of differentiation potential, they are seen as foreign by the patient’s immune system and may trigger rejection. Also, the destruction of embryos to isolate embryonic stem cells raises considerable ethical and legal questions. In contrast, adult stem cells isolated from a patient are not seen as foreign by the body, but they have a limited range of differentiation. Some individuals bank the cord blood or deciduous teeth of their child, storing away those sources of stem cells for future use, should their child need it. Induced pluripotent stem cells are considered a promising advance in the field because using them avoids the legal, ethical, and immunological pitfalls of embryonic stem cells.
business_ethics
Summary 2.1 The Concept of Ethical Business in Ancient Athens The role of ethics in Athens during Greece’s Golden Age (fifth century BCE) was substantial. Aristotle focused on the role of virtue in developing individual character and social stability. He believed a person’s actions determined whether he or she was virtuous, and the point of the virtuous life was happiness, or eudaimonia . Aristotle identified two types of virtues: intellectual and moral. Intellectual virtues were acquired through learning and served as guides to behavior by helping the individual discover truth. Moral virtues were acquired through habit and built character by helping someone pursue what is beneficial and avoid what is harmful in daily life. Aristotle considered phrónēsis , or prudence, the most important virtue, because of its practical application. The thirteenth-century philosopher and theologian Thomas Aquinas agreed with Aristotle that to act dishonorably casts disrepute on all concerned. Ends and means had to be aligned, particularly in business, which provided people’s livelihoods and secured the economic health of the city-state. 2.2 Ethical Advice for Nobles and Civil Servants in Ancient China Confucius (551–479 BCE) attempted to revise ancient Chinese traditions and mores to counter the social chaos of his times. His system of virtue ethics emphasized relationships and, when followed faithfully, led to the dao of humanity, that is, true harmonious living. There were three ways to achieve dao : “whole-hearted sincerity and truthfulness,” the “constant mean,” and “expediency” ( quan ). Someone who lived virtuously became more humane, which resulted in a flourishing individual and an ordered nation. In Confucian virtue ethics, business was viewed as a network of relationships dependent on trust and righteousness. Righteousness was a form of justice that compelled everyone to act in good faith. Considered in this way, justice allows for wealth creation, investment, and strategic planning as long as everyone fulfills his or her role and acts in accordance with the basic pattern of relationships Confucius identified. 2.3 Comparing the Virtue Ethics of East and West Aristotle and Confucius each constructed an ethical system based on virtue, with Aristotle’s anticipated result being happiness and Confucius’s being harmony. For Aristotle, happiness consisted of the search for truth. Confucius looked to create a system that put an end to civil chaos. Although both systems relied on reason and control to achieve their ends, Aristotle placed the locus of ethical behavior on individuals, but he held that a moral upbringing and good political governance also contributed to the formation of moral character. Confucius saw this locus in the family, which provided the basic pattern of relationships for personal and professional life. Reason prevailed throughout, as in the cultivation of a more just and humane person. In a business context, reason and control bear directly on management, leadership, and corporate culture. They constitute a way of cultivating individual virtue and corporate ethos such that the two go hand in hand. The environment or culture of an organization needs individuals of character who can follow their conscience and experience moral conversion. We might envision the emergence of universal values like reason and control that nurture both the individual and the organization. 2.4 Utilitarianism: The Greatest Good for the Greatest Number Jeremy Bentham developed a quantifiable method for determining what was beneficial and what was detrimental. He called this method utilitarianism, because its basic unit, the “util,” acted like a monetary unit. Bentham’s protégé, John Stuart Mill, refined this system to include human rights. His “harm principle” is an outstanding element in his version of utilitarianism. Utilitarianism in business can lead to a bottom-line mentality in which decisions are based on achieving the greatest good for the organization as it pertains to the greatest number of stakeholders, including shareholders and all others affected by the actions of the organization The outcome is the determining factor, not the intent of the actors or whether people are treated humanely. 2.5 Deontology: Ethics as Duty Rejecting dogmatic thinking of all kinds, Kant believed people were not the sum total of reactions to stimuli but complex beings with innate structures of understanding and inborn moral sensitivity. In his view, everyone had a duty to obey a categorical imperative to do the just and moral thing, regardless of the consequences. The outcome of an act was not as important as the intent of the actor and whether the act treated others as ends or means. Here, Kant reflected Aristotelian virtue ethics in seeing people as ends in themselves and not as “living tools” or human resources. This view does not typically govern most management decisions in business; arguably, utilitarianism is the efficient, go-to theory on which corporate leaders often rely. Yet a Kantian understanding of business ethics remains viable even today and sometimes displays itself in the most compassionate and humane actions that evolving commercial organizations take. 2.6 A Theory of Justice Rawls developed a theory of justice based on social contract theory, holding that the natural state of human beings is freedom, not subjugation to a monarch, no matter how benign or well intentioned. Rawls’s theory views human beings as inherently good and, echoing Kant, inclined toward moral rectitude and action. In his theory, Rawls included the “veil of ignorance,” which ensures objectivity in our choices and the avoidance of bias. Criticism of Rawls’s theory focuses primarily on the issue of distribution, because decisions made in ignorance can neither reward innovation and enterprise nor encourage risk.
Chapter Outline 2.1 The Concept of Ethical Business in Ancient Athens 2.2 Ethical Advice for Nobles and Civil Servants in Ancient China 2.3 Comparing the Virtue Ethics of East and West 2.4 Utilitarianism: The Greatest Good for the Greatest Number 2.5 Deontology: Ethics as Duty 2.6 A Theory of Justice Introduction From the time of barter to the age of bitcoin, most people engaged in business transactions have sought trust. Without trust, which is a fundamental outcome of ethical behavior, not just business relationships but all relationships would collapse. To develop insight into our own concepts of ethics, this chapter looks at how ethical systems have developed over time, beginning with the distinction between ethics and the law. Ethics are the standards of behavior to which we hold ourselves accountable in our personal and professional lives. Laws and regulations set the minimal standards by which society lives out those ethical norms. Because laws are minimal standards, it is not uncommon for an act to be legal but generally deemed unethical. The fact is that law and ethics are not always the same. Always, however, they are in dialogue, and each informs the other. The greatest challenge in business decision-making is moving beyond the letter of the law to create a culture of ethics ( Figure 2.1 ). Can you identify a moment in your life when it was hard to follow your conscience, or your personal morality conflicted with societal norms? What was the nature of the conflict, and how did you approach it?
[ { "answer": { "ans_choice": 0, "ans_text": "A" }, "bloom": null, "hl_context": "Aristotle identified two types of virtues , which the philosophical community of his day agreed were objective and not subjective . The two types were intellectual and moral . <hl> Intellectual virtues — including knowledge ( epistḗmē ) , wisdom ( sophíā ) , and , most importantly for Aristotle , prudence ( phrónēsis ) , or practical wisdom — served as guides to behavior ; that is , a person acted prudently based on the wisdom gained over time through the ongoing acquisition and testing of knowledge . <hl> To give an oversimplified but practical application of Aristotelian thinking , a hiring manager acts prudently when assessing a pool of candidates based on knowledge of their backgrounds and on insight gained after years of working in that role . The manager may even use intuitive reason regarding a candidate , which Aristotle believed was another way of arriving at truth . Understood in this way , the manager ’ s intuition is an impression regarding character and someone ’ s potential fit in an organization . Among the intellectual virtues , prudence played the major role because it helped individuals avoid excess and deficiency and arrive at the golden mean between the two . Prudence has been translated as “ common sense ” and “ practical wisdom ” and helps individuals make the right decision in the right way at the right time for the right reason . In Aristotle ’ s view , only the truly prudent person could possess all the moral virtues .", "hl_sentences": "Intellectual virtues — including knowledge ( epistḗmē ) , wisdom ( sophíā ) , and , most importantly for Aristotle , prudence ( phrónēsis ) , or practical wisdom — served as guides to behavior ; that is , a person acted prudently based on the wisdom gained over time through the ongoing acquisition and testing of knowledge .", "question": { "cloze_format": "___ is not an intellectual virtue according to Aristotle.", "normal_format": "Which of the following is not an intellectual virtue according to Aristotle?", "question_choices": [ "the basic order of life", "knowledge", "wisdom", "prudence" ], "question_id": "fs-idm370423120", "question_text": "Which of the following is not an intellectual virtue according to Aristotle?" }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 1, "ans_text": "B" }, "bloom": null, "hl_context": "Aquinas further divided Aristotelian prudence into memory , reason , understanding , docility , shrewdness , foresight , circumspection , and caution . 15 To use these qualities in a constructive way , a business person had to direct them toward an appropriate end , which applies to business today just as it did in fourth-century Athens . A merchant could not make money in a random way but had to keep the needs of customers in mind and conduct business with fair prices and fees . <hl> This exercise of prudence was part of the cosmic order that ensured the right management of the home , the marketplace , and civilization itself . <hl> Similarly , committing fraud or deception to achieve an end , even if that end were good or just , was not considered an honorable act . <hl> Only when ends and means were aligned and worked in harmony were those engaged in the transaction considered virtuous . <hl> This virtue , in turn , would lead to the happiness Aristotle envisioned and toward which his entire system of virtue ethics aimed . Aristotle identified two types of virtues , which the philosophical community of his day agreed were objective and not subjective . The two types were intellectual and moral . <hl> Intellectual virtues — including knowledge ( epistḗmē ) , wisdom ( sophíā ) , and , most importantly for Aristotle , prudence ( phrónēsis ) , or practical wisdom — served as guides to behavior ; that is , a person acted prudently based on the wisdom gained over time through the ongoing acquisition and testing of knowledge . <hl> To give an oversimplified but practical application of Aristotelian thinking , a hiring manager acts prudently when assessing a pool of candidates based on knowledge of their backgrounds and on insight gained after years of working in that role . The manager may even use intuitive reason regarding a candidate , which Aristotle believed was another way of arriving at truth . Understood in this way , the manager ’ s intuition is an impression regarding character and someone ’ s potential fit in an organization . <hl> Among the intellectual virtues , prudence played the major role because it helped individuals avoid excess and deficiency and arrive at the golden mean between the two . <hl> <hl> Prudence has been translated as “ common sense ” and “ practical wisdom ” and helps individuals make the right decision in the right way at the right time for the right reason . <hl> In Aristotle ’ s view , only the truly prudent person could possess all the moral virtues .", "hl_sentences": "This exercise of prudence was part of the cosmic order that ensured the right management of the home , the marketplace , and civilization itself . Only when ends and means were aligned and worked in harmony were those engaged in the transaction considered virtuous . Intellectual virtues — including knowledge ( epistḗmē ) , wisdom ( sophíā ) , and , most importantly for Aristotle , prudence ( phrónēsis ) , or practical wisdom — served as guides to behavior ; that is , a person acted prudently based on the wisdom gained over time through the ongoing acquisition and testing of knowledge . Among the intellectual virtues , prudence played the major role because it helped individuals avoid excess and deficiency and arrive at the golden mean between the two . Prudence has been translated as “ common sense ” and “ practical wisdom ” and helps individuals make the right decision in the right way at the right time for the right reason .", "question": { "cloze_format": "Deliberative prudence does all the following except ________.", "normal_format": "Which of the following does deliberative prudence not do?", "question_choices": [ "align ends and means", "encourage prodigality", "avoid conflict", "prevent rash behavior" ], "question_id": "fs-idm348812336", "question_text": "Deliberative prudence does all the following except ________." }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 2, "ans_text": "C" }, "bloom": null, "hl_context": "For Confucius , the third approach to the Way of humanity was the doctrine of expediency . Where Buddhism and Taoism advocated compassion and Mohism advocated universal love , Confucianism defined righteousness as the virtue that would temper compassion and love so that people could live together not just peacefully but justly . <hl> 25 Righteousness included a practical approach to problem solving that helped politics , diplomacy , and civil administration to flourish . <hl> <hl> This expediency , or quan , is a noteworthy feature of Confucianism . <hl> Originally referring to a piece of metal used in balancing scales , quan is applied when weighing options in a moral dilemma and acts as a counterbalance to achieve fairness , enabling parties in a transaction to arrive at an equitable agreement . Ultimately , quan allows people and institutions to prioritize responsive action over ritual and serves as the way to align what people do with who they are , thus allowing them to become more human . For the businessperson , it might mean not fleeing the “ tawdry ” world of the marketplace but recognizing the humanity within it .", "hl_sentences": "25 Righteousness included a practical approach to problem solving that helped politics , diplomacy , and civil administration to flourish . This expediency , or quan , is a noteworthy feature of Confucianism .", "question": { "cloze_format": "Quan means ___.", "normal_format": "Quan means which of the following?", "question_choices": [ "adherence to the past", "philosophic tradition", "practicality", "insistence on protocol" ], "question_id": "fs-idm229406272", "question_text": "Quan means which of the following?" }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 3, "ans_text": "D" }, "bloom": null, "hl_context": "<hl> Given the vastly different cultural and historical settings of ancient Greece and China , you may be surprised to find similarities between the Aristotelian and Confucian systems of virtue ethics . <hl> Yet not only are there similarities but the two systems share the theme of control . For Aristotle , control manifested itself through the deliberative process of phrónēsis , resulting in virtuous living , harmony , and happiness . This application of practical wisdom was related to self-restraint , or temperance . In Confucian virtue ethics , control was a function of self-regulation ; primitive instincts were held at bay and the person gained the capacity and courage to act more humanely ( Figure 2.6 ) . This achievement of control benefited not only the individual but also the family and , by extension , the nation . Self-regulation was Confucius ’ s way of establishing order . <hl> Aristotle and Confucius each constructed an ethical system based on virtue , with Aristotle ’ s ultimate aim being happiness and Confucius ’ s being harmony . <hl> Each addressed a particular problem . For Aristotle , happiness consisted of the search for truth , which , in turn , required a centered , stable individual who could surmount misfortune or weak character . Confucius looked to settle the soul of the Chinese people by creating a system that reflected the heavenly order on Earth . Both systems rely on reasoned means to achieve reasoned ends .", "hl_sentences": "Given the vastly different cultural and historical settings of ancient Greece and China , you may be surprised to find similarities between the Aristotelian and Confucian systems of virtue ethics . Aristotle and Confucius each constructed an ethical system based on virtue , with Aristotle ’ s ultimate aim being happiness and Confucius ’ s being harmony .", "question": { "cloze_format": "The Analects of Confucius ________.", "normal_format": "Which of the following is correct about the Analects of Confucius?", "question_choices": [ "are similar to Aristotle’s Nicomachean Ethics", "represent an oral tradition", "reflect Buddhist ideals", "codify a system of virtue ethics" ], "question_id": "fs-idm235131200", "question_text": "The Analects of Confucius ________." }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 0, "ans_text": "A" }, "bloom": null, "hl_context": "Given the vastly different cultural and historical settings of ancient Greece and China , you may be surprised to find similarities between the Aristotelian and Confucian systems of virtue ethics . Yet not only are there similarities but the two systems share the theme of control . <hl> For Aristotle , control manifested itself through the deliberative process of phrónēsis , resulting in virtuous living , harmony , and happiness . <hl> <hl> This application of practical wisdom was related to self-restraint , or temperance . <hl> <hl> In Confucian virtue ethics , control was a function of self-regulation ; primitive instincts were held at bay and the person gained the capacity and courage to act more humanely ( Figure 2.6 ) . <hl> This achievement of control benefited not only the individual but also the family and , by extension , the nation . Self-regulation was Confucius ’ s way of establishing order .", "hl_sentences": "For Aristotle , control manifested itself through the deliberative process of phrónēsis , resulting in virtuous living , harmony , and happiness . This application of practical wisdom was related to self-restraint , or temperance . In Confucian virtue ethics , control was a function of self-regulation ; primitive instincts were held at bay and the person gained the capacity and courage to act more humanely ( Figure 2.6 ) .", "question": { "cloze_format": "“Control” as used in this section does not refer to ___.", "normal_format": "“Control” as used in this section does not refer to which of the following?", "question_choices": [ "reverence", "phrónēsis", "temperance", "Confucian self-regulation" ], "question_id": "fs-idm230704112", "question_text": "“Control” as used in this section does not refer to which of the following?" }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 1, "ans_text": "B" }, "bloom": null, "hl_context": "<hl> In a business context , control bears directly on managerial ethics , which is a way of relating to self , employees , and the organization that balances individual and collective responsibility , and in which management also includes planning , organizing , and leading to achieve organizational goals . <hl> <hl> 28 A self-controlled , disciplined manager is able to work through layers of bureaucracy and the complexities of human interaction to attain goals in a way that is responsible and profitable and that enhances the organization ’ s mission and culture . <hl> <hl> These goals are achieved not at the expense of stakeholders but in a way that is fair for all . <hl> <hl> We might even say that righteousness leads to justice , which includes profit . <hl> We saw earlier that neither Aristotle nor Confucius disapproved of profit as long as it benefitted humanity in some way . Both men would have a very definite opinion about the optimization of shareholder wealth .", "hl_sentences": "In a business context , control bears directly on managerial ethics , which is a way of relating to self , employees , and the organization that balances individual and collective responsibility , and in which management also includes planning , organizing , and leading to achieve organizational goals . 28 A self-controlled , disciplined manager is able to work through layers of bureaucracy and the complexities of human interaction to attain goals in a way that is responsible and profitable and that enhances the organization ’ s mission and culture . These goals are achieved not at the expense of stakeholders but in a way that is fair for all . We might even say that righteousness leads to justice , which includes profit .", "question": { "cloze_format": "Managerial ethics is related to ___.", "normal_format": "Managerial ethics is related to which of the following?", "question_choices": [ "shareholder wealth", "righteousness", "bureaucracy", "honor" ], "question_id": "fs-idm237244064", "question_text": "Managerial ethics is related to which of the following?" }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 3, "ans_text": "D" }, "bloom": null, "hl_context": "Given this historical context , it is understandable that Bentham used reason and science to explain human behavior . <hl> His ethical system was an attempt to quantify happiness and the good so they would meet the conditions of the scientific method . <hl> Ethics had to be empirical , quantifiable , verifiable , and reproducible across time and space . Just as science was beginning to understand the workings of cause and effect in the body , so ethics would explain the causal relationships of the mind . Bentham rejected religious authority and wrote a rebuttal to the Declaration of Independence in which he railed against natural rights as “ rhetorical nonsense , nonsense upon stilts . ” 38 Instead , the fundamental unit of human action for him was utility — solid , certain , and factual . Although the ultimate aim of Aristotelian virtue ethics was eudaimonia , later philosophers began to question this notion of happiness . <hl> If happiness consists of leading the good life , what is good ? <hl> <hl> More importantly , who decides what is good ? <hl> Jeremy Bentham ( 1748 – 1842 ) , a progressive British philosopher and jurist of the Enlightenment period , advocated for the rights of women , freedom of expression , the abolition of slavery and of the death penalty , and the decriminalization of homosexuality . <hl> He believed that the concept of good could be reduced to one simple instinct : the search for pleasure and the avoidance of pain . <hl> All human behavior could be explained by reference to this basic instinct , which Bentham saw as the key to unlocking the workings of the human mind . <hl> He created an ethical system based on it , called utilitarianism . <hl> Bentham ’ s protégé , John Stuart Mill ( 1806 – 1873 ) , refined Bentham ’ s system by expanding it to include human rights . In so doing , Mill reworked Bentham ’ s utilitarianism in some significant ways . In this section we look at both systems .", "hl_sentences": "His ethical system was an attempt to quantify happiness and the good so they would meet the conditions of the scientific method . If happiness consists of leading the good life , what is good ? More importantly , who decides what is good ? He believed that the concept of good could be reduced to one simple instinct : the search for pleasure and the avoidance of pain . He created an ethical system based on it , called utilitarianism .", "question": { "cloze_format": "Utilitarianism is a system that ________.", "normal_format": "Utilitarianism is a system that does which of the following?", "question_choices": [ "considers historical conditions", "approaches Aristotelian deliberation", "builds on natural law theory", "attempts to quantify the good" ], "question_id": "fs-idm230689680", "question_text": "Utilitarianism is a system that ________." }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 0, "ans_text": "A" }, "bloom": null, "hl_context": "Why rights ? No doubt , Mill ’ s early life and formation had a great deal to do with his championing of individual freedom . He believed the effort to achieve utility was unjustified if it coerced people into doing things they did not want to do . Likewise , the appeal to science as the arbiter of truth would prove just as futile , he believed , if it did not temper facts with compassion . “ Human nature is not a machine to be built after a model , and set to do exactly the work prescribed for it , but a tree , which requires to grow and develop itself on all sides , according to the tendency of the inward forces which make it a living thing , ” he wrote . 49 Mill was interested in humanizing Bentham ’ s system by ensuring that everyone ’ s rights were protected , particularly the minority ’ s , not because rights were God given but because that was the most direct path to truth . <hl> Therefore , he introduced the harm principle , which states that the “ only purpose for which power can be rightfully exercised over any member of a civilized community , against his will , is to prevent harm to others . <hl> His own good , either physical or moral , is not a sufficient warrant . ” 50", "hl_sentences": "Therefore , he introduced the harm principle , which states that the “ only purpose for which power can be rightfully exercised over any member of a civilized community , against his will , is to prevent harm to others .", "question": { "cloze_format": "In On Liberty, John Stuart Mill ________.", "normal_format": "In On Liberty, what did John Stuart Mill do? ", "question_choices": [ "proposes a harm principle", "exalts libertarianism", "prescribes a consequentialist answer to ethical crises", "rejects rights" ], "question_id": "fs-idm236185056", "question_text": "In On Liberty, John Stuart Mill ________." }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 2, "ans_text": "C" }, "bloom": null, "hl_context": "In 1781 , at the age of fifty-six years , Kant published Critique of Pure Reason ( Kritik der Reinen Vernunft ) in Königsberg , Prussia ( Figure 2.9 ) . 51 Almost immediately , it transformed him from an obscure professor of metaphysics and logic into a preeminent figure in the world of philosophy . <hl> In the 800 - page tome , Kant criticized the way rationalism ( “ pure reason ” ) had assumed the mantle of absolute truth , supplanting both religious faith and empirical science . <hl> <hl> Kant referred to the unquestioned acceptance of rationalism as dogmatism . <hl> Whether Christian or revolutionary , dogmatic thinking was to be avoided because it obscured the truths of science and religion through flawed logic .", "hl_sentences": "In the 800 - page tome , Kant criticized the way rationalism ( “ pure reason ” ) had assumed the mantle of absolute truth , supplanting both religious faith and empirical science . Kant referred to the unquestioned acceptance of rationalism as dogmatism .", "question": { "cloze_format": "Immanuel Kant objected to dogmatism in ________.", "normal_format": "Immanuel Kant objected to dogmatism in which of the following?", "question_choices": [ "religion", "science", "both A and B", "neither A nor B" ], "question_id": "fs-idm229748448", "question_text": "Immanuel Kant objected to dogmatism in ________." }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 2, "ans_text": "C" }, "bloom": null, "hl_context": "<hl> Rawls developed a theory of justice based on the Enlightenment ideas of thinkers like John Locke ( 1632 – 1704 ) and Jean-Jacques Rousseau ( 1712 – 1778 ) , who advocated social contract theory . <hl> Social contract theory held that the natural state of human beings was freedom , but that human beings will rationally submit to some restrictions on their freedom to secure their mutual safety and benefit , not subjugation to a monarch , no matter how benign or well intentioned . This idea parallels that of Thomas Hobbes ( 1588 – 1679 ) , who interpreted human nature to be selfish and brutish to the degree that , absent the strong hand of a ruler , chaos would result . So people willingly consent to transfer their autonomy to the control of a sovereign so their very lives and property will be secured . Rousseau rejected that view , as did Rawls , who expanded social contract theory to include justice as fairness . In A Theory of Justice ( 1971 ) , Rawls introduced a universal system of fairness and a set of procedures for achieving it . He advocated a practical , empirically verifiable system of governance that would be political , social , and economic in its effects .", "hl_sentences": "Rawls developed a theory of justice based on the Enlightenment ideas of thinkers like John Locke ( 1632 – 1704 ) and Jean-Jacques Rousseau ( 1712 – 1778 ) , who advocated social contract theory .", "question": { "cloze_format": "John Rawls’s theory of justice is based on ___.", "normal_format": "John Rawls’s theory of justice is based on which of the following?", "question_choices": [ "cognitive structures", "moral duty", "social contract theory", "survival of the fittest" ], "question_id": "fs-idm231901168", "question_text": "John Rawls’s theory of justice is based on which of the following?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 1, "ans_text": "B" }, "bloom": null, "hl_context": "Rawls ’ s justice theory contains three principles and five procedural steps for achieving fairness . The principles are ( 1 ) an “ original position , ” ( 2 ) a “ veil of ignorance , ” and ( 3 ) unanimity of acceptance of the original position . 61 By original position , Rawls meant something akin to Hobbes ’ understanding of the state of nature , a hypothetical situation in which rational people can arrive at a contractual agreement about how resources are to be distributed in accordance with the principles of justice as fairness . This agreement was intended to reflect not present reality but a desired state of affairs among people in the community . <hl> The veil of ignorance ( Figure 2.10 ) is a condition in which people arrive at the original position imagining they have no identity regarding age , sex , ethnicity , education , income , physical attractiveness , or other characteristics . <hl> <hl> In this way , they reduce their bias and self-interest . <hl> Last , unanimity of acceptance is the requirement that all agree to the contract before it goes into effect . Rawls hoped this justice theory would provide a minimum guarantee of rights and liberties for everyone , because no one would know , until the veil was lifted , whether they were male , female , rich , poor , tall , short , intelligent , a minority , Roman Catholic , disabled , a veteran , and so on .", "hl_sentences": "The veil of ignorance ( Figure 2.10 ) is a condition in which people arrive at the original position imagining they have no identity regarding age , sex , ethnicity , education , income , physical attractiveness , or other characteristics . In this way , they reduce their bias and self-interest .", "question": { "cloze_format": "The “veil of ignorance” ensures ___ .", "normal_format": "The “veil of ignorance” ensures which of the following?", "question_choices": [ "mass delusion", "objectivity", "self-reliance", "Enlightenment reason" ], "question_id": "fs-idm237726192", "question_text": "The “veil of ignorance” ensures which of the following?" }, "references_are_paraphrase": 0 } ]
2
2.1 The Concept of Ethical Business in Ancient Athens Learning Objectives By the end of this section, you will be able to: Identify the role of ethics in ancient Athens Explain how Aristotelian virtue ethics affected business practices It would be hard to overstate the influence of ancient Athens on Western civilization. Athenian achievements in the arts, literature, and government have molded Western consciousness. Perennial themes, such as the search for individual identity and each person’s place in the world, appear in countless novels and Hollywood screenplays. The role of Athenian ethical theories in philosophy has been profound, and Athenian principles continue to be influential in contemporary philosophy. Ethics, as a form of applied philosophy, was a major focus among the leaders of ancient Athens, particularly teachers like Socrates, Plato, and Aristotle. They taught that ethics was not merely what someone did but who someone was. Ethics was a function of being and, as the guiding principle for dealings with others, it naturally applied as well to the sensitive areas of money and commerce. Ancient Athens Like a modern metropolis, the city-state ( polis ) of Athens in the fifth century BCE drew people from far afield who wanted a better life. For some, that life meant engaging in trade and commerce, thanks to the openness of the new democracy established under the lawgiver Cleisthenes in 508 BCE. Others were drawn to Athens’ incredibly rich architecture, poetry, drama, religious practices, politics, and schools of philosophy. Youth traveled there hoping to study with such brilliant teachers as the mathematicians Archimedes and Pythagoras; dramatists like Sophocles and Euripides; historians Herodotus and Thucydides; Hippocrates, the father of medicine; and, of course, the renowned but enigmatic philosopher Socrates. More than being the equivalent of rock stars of their day, these thinkers, scholars, and artists challenged youth to pursue truth, no matter the cost to themselves or their personal ambitions. These leaders were interested not in fame or even in personal development but in the creation of an ideal society. This was the Golden Age of ancient Greece, whose achievements were so profound and enduring that they have formed the pillars of Western civilization for nearly two and a half millennia. Philosophy, in particular, flourished during the Golden Age, with various schools of thought attempting to make sense of the natural and human worlds. The human world was thought to be grounded in the natural world but to transcend it in striking ways, the most obvious being humans use of reason and deliberation. Philosophers like Socrates, Plato, and Aristotle tackled fundamental questions of human existence with such insight that their ideas have remained relevant and universal even at the dawn of artificial intelligence. As British mathematician and philosopher Alfred North Whitehead (1861–1947) observed, “the safest general characterization of the European philosophical tradition is that it consists of a series of footnotes to Plato.” 1 Why are the insights of these Greek philosophers still relevant today? One reason is their development of the ancient concept of virtue . The person most closely associated with virtue in the West, and the development of what is now known as virtue ethics —that is, an ethical system based upon the exercise of certain virtues (loyalty, honor, courage) emphasizing the formation of character—is Plato’s famous pupil Aristotle (384–322 BCE) ( Figure 2.2 ). Aristotelian Virtue Ethics For Aristotle, everything that exists has a purpose, or end, and has been designed to meet that end. For instance, the proper end of birds is to fly, that of fish to swim. Birds and fish have been designed with the appropriate means (feathers, fins) to achieve those ends. Teleology, from the Greek telos meaning goal or aim, is the study of ends and the means directed toward those ends. What is the telos of human beings? Aristotle believed it to be eudaimonia , or happiness. By this, he did not mean happiness in a superficial sense, such as having fun or being content. Rather, he equated happiness with human flourishing, which he believed could be attained through the exercise of the function that distinguishes humans from the natural world: reason. 2 For Aristotle, reason was supreme and best used to increase not wealth but character. “But what is happiness?” he asked. “If we consider what the function of man is, we find that happiness is a virtuous activity of the soul.” 3 However, because humans are endowed not only with reason but also with the capacity to act in an honorable and ethical manner, they may reject their end, either intentionally or by default. The great task of life, then, is to recognize and pursue happiness, no matter the constraints placed on the individual, the most dramatic of which are suffering and death. Birds and fish have little difficulty achieving their ends, and we can assume that much of this is due to their genetic coding. Because happiness might not be genetically encoded in human beings, they must learn how to be happy. How do they do that? According to Aristotle, eudaimonia is achieved by leading a virtuous life, which is attained over time. “Happiness is a kind of activity; and an activity clearly is developed and is not a piece of property already in one’s possession.” 4 Aristotle identified two types of virtues, which the philosophical community of his day agreed were objective and not subjective. The two types were intellectual and moral. Intellectual virtues—including knowledge ( epistḗmē ), wisdom ( sophíā ), and, most importantly for Aristotle, prudence ( phrónēsis ), or practical wisdom—served as guides to behavior; that is, a person acted prudently based on the wisdom gained over time through the ongoing acquisition and testing of knowledge. To give an oversimplified but practical application of Aristotelian thinking, a hiring manager acts prudently when assessing a pool of candidates based on knowledge of their backgrounds and on insight gained after years of working in that role. The manager may even use intuitive reason regarding a candidate, which Aristotle believed was another way of arriving at truth. Understood in this way, the manager’s intuition is an impression regarding character and someone’s potential fit in an organization. Among the intellectual virtues, prudence played the major role because it helped individuals avoid excess and deficiency and arrive at the golden mean between the two. Prudence has been translated as “common sense” and “practical wisdom” and helps individuals make the right decision in the right way at the right time for the right reason. In Aristotle’s view, only the truly prudent person could possess all the moral virtues. The distinction Aristotle made is that the intellectual virtues are acquired purely through learning, whereas the moral virtues are acquired through practice and the development of habits. In contrast to the intellectual virtues, which focused on external acts, the moral virtues had to do with character. They included courage, self-control, liberality, magnificence, honor, patience, and amiability. Some of these virtues had different meanings in ancient Greece than they do today. “Liberal,” for instance, referred not to a political or economic stance but rather to an aspect of personality. Someone would be considered liberal who was open and sharing of him- or herself and his or her talents without fear of rejection or expectation of reciprocity. The paragon of these virtues was the magnanimous individual, someone for whom fame and wealth held little attraction. 5 This person had self-knowledge; was not rash, quick to anger, or submissive to others; and acted with self-respect, control, and prudence. The magnanimous individual achieved happiness by leading a life characterized by reason and will. He or she remained in control of self and did not hand over his or her authority—or moral agency—to others, whether in judgment or in decision-making. “So, magnanimity seems to be a sort of crown of the virtues, because it enhances them and is never found apart from them. This makes it hard to be truly magnanimous, because it is impossible without all-round excellence,” according to Aristotle. 6 The relationship between the intellectual and the moral virtues was not as clear cut as it may appear, however, because Aristotle believed that action preceded character. In other words, the primary way to change character was through consistent, intentional behavior in the direction of virtue. Aristotle gave the example of courage. A person was not courageous first and then went about performing acts of courage. Rather, courage resulted from incremental change, small steps taken over time that molded the person’s character. It relied on a recognition of justice, so that courage was directed toward the right end. The important task was developing the habit of leading the virtuous life. Anyone could do this; however, it was a discipline that had to be learned and practiced with dedication. We can see that this habit of virtue is especially relevant for business today, when the temptation to conform to an established organizational culture is overwhelming even when that culture may permit and even encourage questionable practices. Add the seductive power of money, and anyone’s courage might be tested. The most notable feature of virtue ethics is that it viewed the basic ethical unit—the fundamental agent of morality—as the individual, who lived out his or her worldview publicly. A life of virtue, therefore, took place in the economic and political spheres so that others might participate in and benefit from it. In Athenian society, it was important for business to be conducted competently and ethically. Even though Aristotle was suspicious of business, he acknowledged its importance in preserving and nurturing Athenian democracy. He also praised the creation of money to further the goal of justice, so that a shoemaker and a housebuilder, for instance, could trade their wares on an equal basis. Virtue in the marketplace was demonstrated through ethical behavior, according to Aristotle: “People do in fact seek their own good, and think that they are right to act in this way. It is from this belief that the notion has arisen that such people are prudent. Presumably, however, it is impossible to secure one’s own good independently of domestic and political science.” 7 This belief in the public nature of virtue was crucial for the flourishing of the city-state and also has implications for contemporary business, which must consider the individual, organization, industry, and society in its development and planning. Ethics Across Time and Cultures Athenian Democracy Just as time and place influence people’s perception of ethics, so is their understanding of democracy also subjective. You might be surprised to learn the Athenian version of democracy was significantly different from our own. For instance, although the word “democracy” comes from the Greek for people ( dêmos ) and power ( krátos ), only adult men who owned property could vote, and voting was direct; Athens was not a republic with elected representatives, like the United States. Resident aliens, or metics —those who change their home—were not eligible for citizenship and could not vote. They had limited rights and their status was second class, although this did not stop many of them from attaining wealth and fame. They were often among the best artisans, craftspeople, and merchants in the city-state. Metics were able to conduct business in the marketplace ( agora ) provided they paid special taxes yearly. One of the most famous was Aristotle, who was born outside Athens in northern Greece. Women, even those who were citizens, were not allowed to vote and had limited rights when it came to property and inheritance. Their primary function in Athenian society was the care and management of the home. “The Athenian woman must be the perfect Penelope—a partner to the husband, a guard of the house, and one who practices the virtues defined by her husband. Physical beauty was not to be a goal, nor was it even a primary valued attribute. Total dedication to the welfare of husband, children, and household was the ultimate virtue” 8 ( Figure 2.3 ). Finally, not all transactions were as straightforward as selling Egyptian linen, dried fruit, or spices. Slave traders, too, brought their “wares” to market. Slavery was a customary part of many cultures throughout the ancient world, from Persia to Arabia and Africa and China. In Athens and its surrounding area, it is estimated that during the Golden Age (fifth century BCE) there were 21,000 citizens, 10,000 metics (non-native Athenians who still shared some of the benefits of citizenship), and 400,000 slaves. 9 Despite the Athenian emphasis on virtue and honor, there was little or no objection to owning slaves, because they formed an indispensable part of the economy, providing the labor for agriculture and food production. Slavery persists even today. For instance, it is believed that nearly thirty million people worldwide are living and working as slaves, including three million in China and fourteen million in India. 10 Servitude also exists for migrant workers forced to live and work in inhuman conditions without recourse to legal help or even the basic necessities of life. Such conditions occur in industries as diverse as commercial fishing in Southeast Asia and construction in Qatar. 11 Critical Thinking Consider how democracy has expanded since the Golden Age of Greece, eventually including universal suffrage and fundamental rights for everyone. Although we try not to judge cultures today as having right or wrong practices, we often judge earlier cultures and civilizations. How might you assess a practice like slavery in antiquity without imposing modern values on a civilization that existed more than two and a half millennia ago? Are there absolute truths and values that transcend time and space? If yes, where might these come from? If not, why not? Honorable Behavior in Business The common belief in ancient Greece that business and money were somehow tainted reflected Plato’s concept that the physical world was an imperfect expression, or shadow, of the ideal. Everything in the physical world was somehow less than the ideal, and this included the products of human thought and labor. For example, a cow exists in the physical world as an imperfect and temporary expression of the ideal essence of a cow, what we might call “cowness.” (This imperfection accounted for the many variations found in the earthly creature.) Business, as a human invention based on self-interest, also had no appreciable ideal or end. After all, what was the purpose of making money if not having more money? Any end beyond that was not evident. In other words, money existed simply to replicate itself and was fueled by avarice (the love of money) or greed (the love of material goods). “As for the life of the businessman, it does not give him much freedom of action. Besides, wealth is obviously not the good that we are seeking, because it serves only as a means; i.e., for getting something else,” said Aristotle. 12 Yet, business had an interesting effect that helped invigorate Athenian life and encouraged those engaged in it to be virtuous (or else risk their reputation). This effect was association . Business was based on the free and fair exchange of goods, which brought not only items of merchandise into association with each other but also buyers, sellers, and public officials. The way to ensure ethically sound association was through the exercise of prudence, especially in its demand that people act not rashly but deliberately. This deliberative aspect of prudence provided a way for buyers, sellers, and everyone engaged in a transaction to act honorably, which was of the utmost importance. Honor was not only a foundational virtue but the cultural environment in which the ancient world existed. One of the worst offenses anyone could commit, whether man, woman, free, or slave, was to act in a dishonorable way. Of course, although acting deliberately does not guarantee that one is acting honorably, for Athenians, acting in a calculated way was not an indication of dishonor. Dishonorable acts included any that disturbed the basic order ( dikē ) of life in which everyone had a role, including the gods. Interestingly, the Aristotelian approach to business did not condemn money making or the accumulation of riches. What concerned Aristotle , particularly because of its harmful effects on the individual and the city-state, was greed. Aristotle considered greed an excess that tipped the scales of justice and led to scandal. Money might constitute the bait, but greed causes the person to reach out and grab as much as possible, falling into the trap of scandal. The Greeks considered the exercise of greed an irrational, and therefore ignoble, act. Only attention to honor and deliberative prudence could save someone from acting so foolishly. Honor in ancient Greece was not just an individual characteristic but also a function of the group to which an individual belonged, and the person derived self-esteem from membership in that group. Civic virtue consisted of honorable living in community. Business scandals today often arise not from conflicts of interest but from conflicts of honor in which employees feel torn by their allegiance to a coworker, a supervisor, or the organization. 13 Although few people would use the term honor to describe contemporary workplace culture or corporate mission, nearly everyone understands the importance of reputation and its impact, positive or negative, on a business. Reputation is no accident. It is the product of a culture formed by individual and group effort. That effort is directed, intentional, and ongoing. According to Aristotle, and later thinkers who expanded upon his work, such as thirteenth-century philosopher and theologian Thomas Aquinas , to act dishonorably casts disrepute on all concerned. Ends and means had to be aligned, particularly in business, which provided people’s livelihoods and secured the economic health of the city-state. Acting honorably meant trying to be magnanimous in all transactions and rising above obsession with baser instincts. The honorable person was magnanimous, prudent, fair, and interested in self-advancement as long as it did not injure personal integrity or the body politic. The importance of prudence is evident because, said Aristotle, it is “concerned with human goods, i.e., things about which deliberation is possible; for we hold that it is the function of the prudent man to deliberate well; and nobody deliberates about things that cannot be otherwise, or that are not means toward an end, and that end is a practical good. And the man who is good at deliberation generally is the one who can aim, by the help of his calculation, at the best of the goods attainable.” 14 Aquinas further divided Aristotelian prudence into memory, reason, understanding, docility, shrewdness, foresight, circumspection, and caution. 15 To use these qualities in a constructive way, a business person had to direct them toward an appropriate end, which applies to business today just as it did in fourth-century Athens. A merchant could not make money in a random way but had to keep the needs of customers in mind and conduct business with fair prices and fees. This exercise of prudence was part of the cosmic order that ensured the right management of the home, the marketplace, and civilization itself. Similarly, committing fraud or deception to achieve an end, even if that end were good or just, was not considered an honorable act. Only when ends and means were aligned and worked in harmony were those engaged in the transaction considered virtuous. This virtue, in turn, would lead to the happiness Aristotle envisioned and toward which his entire system of virtue ethics aimed. Ethics Across Time and Cultures Three Forms of Justice Along with honor, justice—as depicted in the image at the beginning of this chapter—formed part of the cultural environment of Athenian society. Citizens often relied on litigation to settle disputes, particularly conflicts over business transactions, contracts, inheritance, and property. Justice existed in three forms, as it does today: legal, commutative, and distributive. In legal justice , the city-state was responsible for establishing fair laws for the welfare of its citizens. Commutative justice characterized relationships among individuals. Courts attempted to correct harms inflicted and return what had been unlawfully taken away from plaintiffs. Distributive justice governed the duty of the city-state to distribute benefits and burdens equitably among the people. We can see these forms of justice at work today in very practical ways. For instance, within the framework of commutative justice, businesses are often held responsible ethically and financially for any harm caused by their products. And distributive justice is debated in such hotly contested issues as corporate and individual tax rates, universal health coverage, state and federal income assistance, subsidized housing, social security eligibility, college tuition aid (e.g., Pell grants), and similar programs designed to create a “safety net” for those least fortunate. Some safety net programs have been criticized for their excessive cost, inefficiency, and unfairness to those who pay into them while receiving no benefit or say in their administration. Critical Thinking How is the ancient concept of distributive justice understood in today’s political debate? What are the underlying values that inform each side of the debate (e.g., values like wealth maximization and corporate social responsibility)? Can these sides be reconciled and, if so, what must happen to bring them together? Does virtue have a role to play here; if so, how? Link to Learning For a further discussion of justice, read this article on justice and fairness from the Markkula Center for Applied Ethics. How, exactly, did honor and deliberative prudence prevent someone from acting foolishly in life and unethically in business? And what does it look like to follow these virtues today? 2.2 Ethical Advice for Nobles and Civil Servants in Ancient China Learning Objectives By the end of this section, you will be able to: Identify the key features of Confucian virtue ethics Explain how Confucian virtue ethics can be applied to contemporary business The teachings and writings of Confucius (551–479 BCE; also called Kung Fu Tzu or Master Kung) not only have endured more than two and a half millennia but have influenced Chinese culture to such a degree that they remain part of the national character. In classical Confucianism, the practice of virtue constitutes the essence of governance. Differing from Aristotelian virtue ( arête ), Confucian virtue emphasizes relationships. Aristotle shows how a self-determining person might live well in society. Confucius showed how a relationship-determining person can live well with others. The reasons for this distinction will become clearer throughout the section. As an iconic figure, Confucius had an impact on politics, literature, civil administration, diplomacy, and religion in China. Yet, by most accounts, he considered himself a failure, never having achieved the position and security he sought during his lifetime. However, his story is a testament to the reward of a life lived with integrity and simplicity. Social Upheaval in Ancient China More than a century and a half before Aristotle and on the other side of the globe, Confucius, a wandering preacher from the principality of Lu in China, also struggled to answer life’s questions, although in a practical rather than a philosophical way. Confucius committed himself to healing the social divisions that were tearing China apart under the declining Zhou Dynasty. Those divisions led to what historians call the “Period of the Warring States,” which persisted for two hundred years after Confucius’s death. It was a time of constant warfare and violence. 16 To counter the social disintegration he found everywhere, Confucius looked to the past, or “the wisdom of the ancients.” He called for a “return to li ,” which was the proper order of the universe in which everyone had a role to play and there was harmony in the world. 17 We might see this harmony in a contemporary business setting as a team of people bringing different talents to bear on a specific project for the good (and profit) of the company. In this sense, li refers to doing those tasks in collaboration with others to achieve the mission of the organization. For Confucius, li was expressed through ritual acts. When the correct rituals were followed in the right way with the right intention for the right end, all was well. Of course, corporate rituals also exist, and like all ritual acts, they reinforce cohesion and identity within the group. Identifying them helps improve employee awareness, productivity, and, perhaps, happiness. One example of this would be new-employee orientation, which is intended to acclimate newcomers to the corporate culture, the company ethos, and the traditions associated with the way the firm does business. Finally, anticipating Aristotle’s golden mean, li emphasized the middle ground between deficiency and excess. “Nothing in excess” was its guiding principle. 18 Huston Smith, noted historian of world religions, has observed that the widespread adoption of Confucius’s teachings within a generation of his death was not due to the originality of his ideas. 19 What made the humble scholar the greatest cultural force in China’s history was chance. Confucius appeared on the scene at the right time, offering a fractured country an alternative to two extremes, neither of which was working. These were a realism that was tyrannical and relied on brute force to restrain the rivaling factions, and an idealistic approach called Mohism that was based on universal love and mutual aid. Confucius rejected the first as crude and the second as utopian. 20 Instead, he offered a practical but empathetic approach, a sort of tough love for the times. Link to Learning Read this article that gives a helpful historical background on Confucianism to learn more. Confucian Virtue Ethics Scholars believe that, like Aristotle, Confucius stressed the virtuous life in his ethical system, with the goal of creating a junzi , or a person who was gracious, magnanimous, and cultured: in other words, a flourishing human being. A junzi exhibited refinement, self-control, and balance in all things, acting neither rashly nor timidly. Such a person was the opposite of a “small” individual, who spent his or her time embroiled in petty rivalries and for whom power was the ultimate measure of success. The concept of junzi and the Aristotelian magnanimous individual have much in common, except that for Confucius, there was added urgency. To be a junzi was a matter not just of honor but of survival. It is no exaggeration to say that China’s very existence depended upon the ability of individuals—nobles and peasants alike—to rise above the barbarity around them and embrace a way of life directed both outward toward social, political, and administrative reform and inward toward spiritual development. Confucius ( Figure 2.4 ) believed that living the virtues he taught would achieve both these ends. The keystone of Confucius’s deliberate tradition was the dao of humanity, or the Way, which established humanity as the answer to rampant lawlessness. 21 Confucius believed people were inherently good and that the way to stop inhuman behavior was to make them even better, or more human. He identified three means to do this, which we explore next: “whole-hearted sincerity and truthfulness,” the “constant mean,” and “expediency” ( quan ). 22 Specific virtues like moral character, righteousness, wisdom, courage, respect, filial piety, and simplicity formed part of these means. Someone who lived virtuously became more human, which resulted in a flourishing individual and an ordered world. “Whole-hearted sincerity and truthfulness” meant more than sincerity, because even liars can be convincing. The sincerity Confucius had in mind was closer to loyalty, and the thing to which humans had to be loyal was truth. Confucius intended to counter the blind loyalty that had contributed to the eruption of anarchy throughout China. For instance, if a subject were called upon to offer advice, the subject had to be truthful, even though the ruler might not like the advice, which actually happened to Confucius, causing him to resign his post as minister of justice in Lu. 23 What a subject owed the ruler was not cloying deference but the truth, which would benefit everyone in the long run. The implications for ethical behavior in modern corporations may be obvious. Reporting unethical behavior as a whistleblower or even standing up for truth in a meeting is sometimes easier said than done, which is why living virtuously requires disciplined practice and the support of like-minded individuals. The “constant mean” refers to balance between excess and deficiency in an existential and in a practical sense. We are to follow the middle path, avoiding extremes of thought and action through ritual acts. We cannot claim to lead a balanced life; we must show it by performing acts that maintain personal and collective order. The Book of Li catalogues many of these acts, which form a guide for proper living, indicating the correct way to maintain the five great relationships that support Chinese society: parent/child, husband/wife, elder/junior sibling, master/apprentice, and ruler/subject. Confucius and his peers believed that properly observing these key five relationships was essential for social good and would invoke divine favor on the people. Note that three of these are relationships within the family. The family was the basic unit of society and Confucius’s hope for reform, because it was the primary and most influential school of character, virtue, and conscience. Thus, the return to li takes on greater significance than a simple longing for an idyllic past. As Huston Smith noted, “that three of the Five Relationships pertain within the family is indicative of how important Confucius considered this institution to be. In this he was not inventing but continuing the Chinese assumption that the family is the basic unit of society. This assumption is graphically embedded in Chinese legend, which credits the hero who ‘invented’ the family with elevating the Chinese from the animal to human level.” 24 What Would You Do? Yijing The five great relationships upon which Chinese civilization is built prescribed definite roles for the social classes and sexes. As in ancient Greece, women in ancient China were in charge of domestic duties and care of the family. They were neither expected nor believed able to assume duties outside the home and certainly not in the competitive world of business. Yet consider the fictional case of Yijing. Yijing was the daughter of the merchant Bei Li, who sold farming tools and agricultural products in Cao, which bordered Lu. Bei Li’s business was very successful and he took great pride in it. He had three sons who worked with him, but none had the head for business that his daughter Yijing had. Moreover, none of them wanted to take over the business after his death. When Yijing begged for a chance to run the business for her father, he agreed, but he insisted she disguise herself as a man when traveling and doing business in the family name. If people knew she was a woman, they would ridicule the family and take advantage of her. Although surprised by her father’s request, Yijing agreed and eventually took over the business, making it extremely prosperous. Critical Thinking If you were Yijing, what would you have done? For Confucius, the third approach to the Way of humanity was the doctrine of expediency. Where Buddhism and Taoism advocated compassion and Mohism advocated universal love, Confucianism defined righteousness as the virtue that would temper compassion and love so that people could live together not just peacefully but justly. 25 Righteousness included a practical approach to problem solving that helped politics, diplomacy, and civil administration to flourish. This expediency, or quan , is a noteworthy feature of Confucianism. Originally referring to a piece of metal used in balancing scales, quan is applied when weighing options in a moral dilemma and acts as a counterbalance to achieve fairness, enabling parties in a transaction to arrive at an equitable agreement. Ultimately, quan allows people and institutions to prioritize responsive action over ritual and serves as the way to align what people do with who they are, thus allowing them to become more human. For the businessperson, it might mean not fleeing the “tawdry” world of the marketplace but recognizing the humanity within it. One example of the use of quan is the Broad Group, a Chinese manufacturer of central air conditioning products. The company produces clean energy systems and has developed an alternative to Freon. The new coolant has changed the way energy is delivered to such an extent that Zhang Yue, the company’s chief executive officer, was awarded the Champions of the Earth prize by the United Nations in 2011 for his work in green energy. 26 Certainly, there is more opportunity for sustainable manufacturing and ethical business practices throughout China, and the state is attempting to promote such efforts. A Confucian Business Model The spirituality that emerges from quan as righteousness is not solely about the individual; it is about the act itself, that is, the transaction, whether that takes place in a market, shop, or loading dock. When righteousness is directed outward in this way, it becomes justice, compelling all parties in a transaction to act in good faith or risk upsetting the proper order of things. Justice in this sense allows for wealth creation, investment, and strategic planning as long as all fulfill their roles and act in the manner of a junzi . An overarching spirituality of business may even develop, arising from the people who collectively make up the company. This is a traditionally Confucian way of looking at corporate culture, as the reflection of a larger network of relationships. The other two Confucian ways of humanity also relate to business, because wholeheartedness and sincerity can serve as models of risk assessment, requiring clearheaded thinking and action balanced with respect for markets, competitors, and stakeholders. The dao of humanity rejects the premise that greed reigns supreme by itself. Instead, its ethical counterpart is truth. Both qualities exist within business practices. In this ethical framework, loyalty to truth is not just a stock phrase but a commitment to value in all aspects of an enterprise, such as sales, finance, marketing, and the employment and hiring chain. An investment advisor might recommend the constant mean to clients so their money is in a diversified portfolio with a long-term strategy. The dao of humanity, wholeheartedness, sincerity, and the other virtues are treated in The Analects ( Figure 2.5 ). Some have criticized Confucianism for impeding progress in China in areas like education, the natural sciences, and business, because it has failed to adapt to the modern context. High-frequency trading, blockchain technology, artificial intelligence, and robotics do not work with cultural values thousands of years old, these critics say, so what we need is a new consciousness for a new era in human history. However, these criticisms miss the point. Confucius was interested in the same thing that concerned Aristotle—namely, the character of the person or persons making decisions rather than the decisions themselves. The importance of character has been proven repeatedly through business scandals like Enron, LIBOR, and the 2008 financial crisis, as well as the recent problems of Uber and Volkswagen, in which personal irresponsibility resulted in disaster. Indeed, business schools now offer seminars for executives integrating virtue ethics—both Aristotelian- and Confucian-inspired models—in leadership development. Link to Learning For a concise breakdown of the rise and collapse of Enron, see the video "Enron: The Biggest Fraud in History" . The recent campaign of China’s central government against unethical business practices has made a point of prosecuting executives for corruption in the form of bribery, kickbacks, and embezzlement, demonstrating that some Confucian thought has survived from ancient times. Jack Ma, cofounder of the giant Chinese ecommerce site Alibaba, has called this “clean communism,” which might be another way of characterizing the form of state-sponsored capitalism that exists in China. 27 Of course, the former Communist regime did not embrace Confucian virtue. Mao Zedong was deeply suspicious of Confucius, holding him to be a relic of the Imperial Era and having little value for the new China he intended to create with the founding of the People’s Republic of China in 1949. Link to Learning To what extent are children in China responsible for their parents’ businesses? In this article, Kelly Zong, daughter of billionaire Zong Qinghua, explains how she believes modern-day China has “lost its soul” through selfish individualism and an obsession with wealth. If Kelly Zong is correct, would it be safe to say that China needs another return to ancient wisdom? Why or why not? Do you agree with her assessment of the current generation and individualism? 2.3 Comparing the Virtue Ethics of East and West Learning Objectives By the end of this section, you will be able to: Compare the origins and goals of virtue ethics in the East and the West Describe how these systems each aimed to establish a social order for family and business Identify potential elements of a universally applied business ethic Aristotle and Confucius each constructed an ethical system based on virtue, with Aristotle’s ultimate aim being happiness and Confucius’s being harmony. Each addressed a particular problem. For Aristotle, happiness consisted of the search for truth, which, in turn, required a centered, stable individual who could surmount misfortune or weak character. Confucius looked to settle the soul of the Chinese people by creating a system that reflected the heavenly order on Earth. Both systems rely on reasoned means to achieve reasoned ends. East Meets West Given the vastly different cultural and historical settings of ancient Greece and China, you may be surprised to find similarities between the Aristotelian and Confucian systems of virtue ethics. Yet not only are there similarities but the two systems share the theme of control . For Aristotle, control manifested itself through the deliberative process of phrónēsis , resulting in virtuous living, harmony, and happiness. This application of practical wisdom was related to self-restraint, or temperance. In Confucian virtue ethics, control was a function of self-regulation; primitive instincts were held at bay and the person gained the capacity and courage to act more humanely ( Figure 2.6 ). This achievement of control benefited not only the individual but also the family and, by extension, the nation. Self-regulation was Confucius’s way of establishing order. In a business context, control bears directly on managerial ethics , which is a way of relating to self, employees, and the organization that balances individual and collective responsibility, and in which management also includes planning, organizing, and leading to achieve organizational goals. 28 A self-controlled, disciplined manager is able to work through layers of bureaucracy and the complexities of human interaction to attain goals in a way that is responsible and profitable and that enhances the organization’s mission and culture. These goals are achieved not at the expense of stakeholders but in a way that is fair for all. We might even say that righteousness leads to justice, which includes profit. We saw earlier that neither Aristotle nor Confucius disapproved of profit as long as it benefitted humanity in some way. Both men would have a very definite opinion about the optimization of shareholder wealth. Despite these similarities between the two traditions, there are differences—the most notable being the locus of ethics. Aristotle placed this locus on individuals, who were called to fulfill their purpose honorably, accepting fate with dignity and aplomb. The basis of this acceptance was reason. For Confucius, reflecting the historical plight of China, the locus was the family, which he envisioned as putting an end to anarchy and setting the nation on its proper course by providing the basic pattern of relationships for personal and professional life. To be sure, family counted for Aristotle just as the individual counted for Confucius, but the emphasis in each system was different. Aristotle acknowledged that “a solitary man has a hard life, because it is not easy to keep up a continuous activity by oneself; but in company with others and in relation to others it is easier.” 29 Regardless of the source of ethical behavior, those engaged in business were required to act with accountability and responsibility. They were accountable to customers and suppliers when delivering commodities like figs, pottery, or olive oil. And they had to conduct themselves responsibly to maintain their personal and professional reputation. Thus, business was the perfect expression of ethics in both East and West, because it provided a forum within which virtues were tested in very real ways. Confucius urged each follower to be a great or humane person, or ru , not a small one. 30 This was so important that the school established after his death was known as the Ru School, and the principles it taught are called Ruism. 31 Personal and Professional Roles Another important characteristic of Eastern and Western systems of virtue ethics is the integration of personal and professional life. A person could not act one way at home and a completely different way in public, especially civic leaders, merchants, teachers, and rulers. The modern tendency to compartmentalize various aspects of ourselves to accommodate circumstances would have puzzled those living in ancient Greece or China. A retail manager who contributes generously to help protect endangered species but thinks nothing of working the sales staff to the point of burnout to achieve monthly goals has not successfully integrated the personal and the professional, for instance, and even poses obstacles to individual happiness and life in the community. Everyone desires efficiency in business, but compartmentalizing our personal and professional ideals can lead to “dispersed personal accountability” in an organization and the kind of financial meltdown that occurred, through greed and rule-breaking, in the housing and financial industries and led to the worldwide recession of 2008. 32 What might the integration of personal and professional life look like, and how can we apply it within the relationships that are the foundation of business? To answer this question, consider the essence of the virtuous person that each ethical system strove to create. For Aristotle, the virtuous person saw the truth in every kind of situation. Once acknowledged and recognized, the truth could not be denied without compromising honor. Similarly, Confucius taught that “A gentleman will not, for the space of a meal, depart from humanity. In haste and flurry, he adheres to it; in fall and stumble, he adheres by it.” 33 Despite the emphasis these systems placed on character, however, character was not ultimately what defined the virtuous individual, family, city-state, or nation. Instead, it was the individual’s transformation, through education, into a different kind of being who will act virtuously even if no one is watching. When the person concentrates on the means used to achieve an end, eventually the means become a way of life even more important than the end itself. It is not merely that the means must match the end, but that they come to define the virtuous person. The integration of personal and professional lives has two effects: motive and awareness . Motive is the willingness to do the right thing because it is the right thing, even though there may be no perceived benefit. Arguably, it is here that the individual’s true nature is revealed. The other effect, awareness, is the ability to see the ethical dimension in all events, choices, decisions, and actions. Many business scandals could be avoided if more people understood the value of human capital and the need to see the larger picture; to put it differently: responsibility over profitability. Or, as Confucius would say, it is the person who can broaden the Way, not the Way that broadens the person. 34 Is There a Universal Ethics? A fundamental question in the study of ethics is whether we can identify universal, objective moral truths that cut across cultures, geographic settings, and time. At the most foundational level, the answer might be yes. As Aristotle noted, ethics is not a science but an art. 35 Perhaps the best way to answer the question is to consider the methods used for moral decision-making. This strategy would be in line with Aristotelian and Confucian models if we assume that once they attain insight, most people will follow their conscience and act in reasonable, responsible ways. Methods of decision-making then could be adapted to any context or dilemma. But what constitutes a reasonable, responsible method, and who gets to choose it? It is possible that standards of ethical conduct could be created to guide business affairs fairly and justly. Such standards already exist in most industries and professions. The Generally Accepted Accounting Principles (GAAP) give direction to those working in accounting and finance in the United States. The International Standards Organization offers guidelines and protocols for many industries. Together with governmental regulation, these might serve as the basis for ethical behavior, perhaps even globally. Of course, those fashioning guidelines would have to be sensitive to individual autonomy and national sovereignty, especially when it comes to international jurisdiction, privacy, and human rights. For example, the International Financial Reporting Standards serve as a kind of international GAAP to help companies report financial results in a common accounting language across national boundaries. Despite our best efforts, someone who wishes to conduct business selfishly and unethically always will be drawn to do so unless given a compelling incentive not to. It is evident why Aristotle and Confucius stressed the importance of schooling. Perhaps what is needed now, building on these two ancient approaches, is business education focused on transformation rather than on conformity to guidelines. This proposal touches the core of both Aristotelian and Confucian teachings: training and education. Training and education help internalize in us more altruistic business practices. They also permit greater integration between our personal and professional understandings of the way we should treat friends, family, customers, and clients. No matter the context, we are then encouraged to treat others with honesty and respect, so that even someone certain to get away with the most outrageous corruption or money-laundering scheme would not do it. Why not? Because doing so would be a betrayal of the person’s conscience and identity. A business education that is truly effective—one for the twenty-first century—would produce a graduate who could stand up and say no to that kind of self-betrayal. What Would You Do? Scenario with Aristotle and Confucius Imagine a scenario in which Aristotle and Confucius sit down to discuss Chiquita Brands International, a global produce conglomerate that paid “protection” money to right-wing and Marxist guerrilla groups in Colombia between 1997 and 2004 to ensure there would be no violence against its employees, banana plantations, and facilities. The payment violated the U.S. Foreign Corrupt Practices Act (1977), which prohibits bribes and kickbacks to foreign officials. Chiquita claimed it was the victim of extortion and had no choice. However, for its actions, it eventually paid $25 million in fines to the U.S. government. In 2007, a group of Colombians filed a lawsuit against the company under the Alien Tort Claims Act, alleging that, because of its illegal payments, Chiquita was “complicit in extrajudicial killings, torture, forced disappearances, and crimes against humanity” perpetrated against plantation workers by the guerilla “death squads.” 36 The case went to the U.S. Supreme Court in 2015, but the Court declined to hear it. Critical Thinking What do you suppose Confucius and Aristotle, teachers of virtue ethics, would say about the Colombians’ case, and how would they go about assessing responsibility? What would they identify as the crime committed? Would they think the executives at Chiquita had acted prudently, cravenly, or deceitfully? What would you do if confronted with this case? Link to Learning The Business and Human Rights Resource Centre provides helpful, detailed information concerning ethics cases and the role of business in society, including more information about the Chiquita lawsuit and other interesting cases. 2.4 Utilitarianism: The Greatest Good for the Greatest Number Learning Objectives By the end of this section, you will be able to: Identify the principle elements of Jeremy Bentham’s utilitarianism Distinguish John Stuart Mill’s modification of utilitarianism from Bentham’s original formulation of it Evaluate the role of utilitarianism in contemporary business Although the ultimate aim of Aristotelian virtue ethics was eudaimonia , later philosophers began to question this notion of happiness. If happiness consists of leading the good life, what is good? More importantly, who decides what is good? Jeremy Bentham (1748–1842), a progressive British philosopher and jurist of the Enlightenment period, advocated for the rights of women, freedom of expression, the abolition of slavery and of the death penalty, and the decriminalization of homosexuality. He believed that the concept of good could be reduced to one simple instinct: the search for pleasure and the avoidance of pain. All human behavior could be explained by reference to this basic instinct, which Bentham saw as the key to unlocking the workings of the human mind. He created an ethical system based on it, called utilitarianism . Bentham’s protégé, John Stuart Mill (1806–1873), refined Bentham’s system by expanding it to include human rights. In so doing, Mill reworked Bentham’s utilitarianism in some significant ways. In this section we look at both systems. Maximizing Utility During Bentham’s lifetime, revolutions occurred in the American colonies and in France, producing the Bill of Rights and the Déclaration des Droits de l’Homme (Declaration of the Rights of Man), both of which were based on liberty, equality, and self-determination. Karl Marx and Friedrich Engels published The Communist Manifesto in 1848. Revolutionary movements broke out that year in France, Italy, Austria, Poland, and elsewhere. 37 In addition, the Industrial Revolution transformed Great Britain and eventually the rest of Europe from an agrarian (farm-based) society into an industrial one, in which steam and coal increased manufacturing production dramatically, changing the nature of work, property ownership, and family. This period also included advances in chemistry, astronomy, navigation, human anatomy, and immunology, among other sciences. Given this historical context, it is understandable that Bentham used reason and science to explain human behavior. His ethical system was an attempt to quantify happiness and the good so they would meet the conditions of the scientific method. Ethics had to be empirical, quantifiable, verifiable, and reproducible across time and space. Just as science was beginning to understand the workings of cause and effect in the body, so ethics would explain the causal relationships of the mind. Bentham rejected religious authority and wrote a rebuttal to the Declaration of Independence in which he railed against natural rights as “rhetorical nonsense, nonsense upon stilts.” 38 Instead, the fundamental unit of human action for him was utility —solid, certain, and factual. What is utility? Bentham’s fundamental axiom, which underlies utilitarianism , was that all social morals and government legislation should aim for producing the greatest happiness for the greatest number of people. Utilitarianism, therefore, emphasizes the consequences or ultimate purpose of an act rather than the character of the actor, the actor’s motivation, or the particular circumstances surrounding the act. It has these characteristics: (1) universality, because it applies to all acts of human behavior, even those that appear to be done from altruistic motives; (2) objectivity, meaning it operates beyond individual thought, desire, and perspective; (3) rationality, because it is not based in metaphysics or theology; and (4) quantifiability in its reliance on utility. 39 Ethics Across Time and Cultures The “Auto-Icon” In the spirit of utilitarianism, Jeremy Bentham made a seemingly bizarre request concerning the disposition of his body after his death. He generously donated half his estate to London University, a public university open to all and offering a secular curriculum, unusual for the times. (It later became University College London.) Bentham also stipulated that his body be preserved for medical instruction ( Figure 2.7 ) and later placed on display in what he called an “auto-icon,” or self-image. The university agreed, and Bentham’s body has been on display ever since. Bentham wanted to show the importance of donating one’s remains to medical science in what was also perhaps his last act of defiance against convention. Critics insist he was merely eccentric. Critical Thinking What do you think of Bentham’s final request? Is it the act of an eccentric or of someone deeply committed to the truth and courageous enough to act on his beliefs? Do you believe it makes sense to continue to honor Bentham’s request today? Why is it honored? Do requests have to make sense? Why or why not? Bentham was interested in reducing utility to a single index so that units of it could be assigned a numerical and even monetary value, which could then be regulated by law. This utility function measures in “utils” the value of a good, service, or proposed action relative to the utilitarian principle of the greater good, that is, increasing happiness or decreasing pain. Bentham thus created a “hedonic calculus” to measure the utility of proposed actions according to the conditions of intensity, duration, certainty, and the probability that a certain consequence would result. 40 He intended utilitarianism to provide a reasoned basis for making judgments of value rather than relying on subjectivity, intuition, or opinion. The implications of such a system on law and public policy were profound and had a direct effect on his work with the British House of Commons, where he was commissioned by the Speaker to decide which bills would come up for debate and vote. Utilitarianism provided a way of determining the total amount of utility or value a proposal would produce relative to the harm or pain that might result for society. Utilitarianism is a consequentialist theory. In consequentialism , actions are judged solely by their consequences, without regard to character, motivation, or any understanding of good and evil and separate from their capacity to create happiness and pleasure. Thus, in utilitarianism, it is the consequences of our actions that determine whether those actions are right or wrong. In this way, consequentialism differs from Aristotelian and Confucian virtue ethics, which can accommodate a range of outcomes as long as the character of the actor is ennobled by virtue. For Bentham, character had nothing to do with the utility of an action. Everyone sought pleasure and avoided pain regardless of personality or morality. In fact, too much reliance on character might obscure decision-making. Rather than making moral judgments, utilitarianism weighed acts based on their potential to produce the most good (pleasure) for the most people. It judged neither the good nor the people who benefitted. In Bentham’s mind, no longer would humanity depend on inaccurate and outdated moral codes. For him, utilitarianism reflected the reality of human relationships and was enacted in the world through legislative action. To illustrate the concept of consequentialism, consider the hypothetical story told by Harvard psychologist Fiery Cushman. When a man offends two volatile brothers with an insult, Jon wants to kill him; he shoots but misses. Matt, who intends only to scare the man but kills him by accident, will suffer a more severe penalty than his brother in most countries (including the United States). Applying utilitarian reasoning, can you say which brother bears greater guilt for his behavior? Are you satisfied with this assessment of responsibility? Why or why not? 41 Link to Learning A classic utilitarian dilemma considers an out-of-control streetcar and a switch operator’s array of bad choices. Watch the video on the streetcar thought experiment and consider these questions. How would you go about making the decision about what to do? Is there a right or wrong answer? What values and criteria would you use to make your decision about whom to save? Synthesizing Rights and Utility As you might expect, utilitarianism was not without its critics. Thomas Hodgskin (1787–1869) pointed out what he said was the “absurdity” of insisting that “the rights of man are derived from the legislator” and not nature. 42 In a similar vein, the poet Samuel Taylor Coleridge (1772–1834) accused Bentham of mixing up morality with law. 43 Others objected that utilitarianism placed human beings on the same level as animals and turned people into utility functions. There were also complaints that it was mechanistic, antireligious, and too impractical for most people to follow. John Stuart Mill sought to answer these objections on behalf of his mentor but then offered a synthesis of his own that brought natural rights together with utility, creating a new kind of utilitarianism, one that would eventually serve to underpin neoclassical economic principles. 44 Mill’s father, James, was a contemporary and associate of Bentham’s who made sure his son was tutored in a rigorous curriculum. According to Mill, at an early age he learned enough Greek and Latin to read the historians Herodotus and Tacitus in their original languages. 45 His studies also included algebra, Euclidean geometry, economics, logic, and calculus. 46 His father wanted him to assume a leadership position in Bentham’s political movement, known as the Philosophical Radicals. 47 Unfortunately, the intensity and duration of Mill’s schooling—utilitarian conditions of education—were so extreme that he suffered a nervous breakdown at the age of twenty years. The experience left him dissatisfied with Bentham’s philosophy of utility and social reform. As an alternative, Mill turned to Romanticism and poets like Coleridge and Johann Wolfgang Goethe (1749–1832). 48 What he ended up with, however, was not a rejection of utilitarianism but a synthesis of utility and human rights. Why rights? No doubt, Mill’s early life and formation had a great deal to do with his championing of individual freedom. He believed the effort to achieve utility was unjustified if it coerced people into doing things they did not want to do. Likewise, the appeal to science as the arbiter of truth would prove just as futile, he believed, if it did not temper facts with compassion. “Human nature is not a machine to be built after a model, and set to do exactly the work prescribed for it, but a tree, which requires to grow and develop itself on all sides, according to the tendency of the inward forces which make it a living thing,” he wrote. 49 Mill was interested in humanizing Bentham’s system by ensuring that everyone’s rights were protected, particularly the minority’s, not because rights were God given but because that was the most direct path to truth. Therefore, he introduced the harm principle , which states that the “only purpose for which power can be rightfully exercised over any member of a civilized community, against his will, is to prevent harm to others. His own good, either physical or moral, is not a sufficient warrant.” 50 To be sure, there are limitations to Mill’s version of utilitarianism, just as there were with the original. For one, there has never been a satisfactory definition of “harm,” and what one person finds harmful another may find beneficial. For Mill, harm was defined as the set back of one’s interests. Thus, harm was defined relative to an individual’s interests. But what role, if any, should society play in defining what is harmful or in determining who is harmed by someone’s actions? For instance, is society culpable for not intervening in cases of suicide, euthanasia, and other self-destructive activities such as drug addiction? These issues have become part of the public debate in recent years and most likely will continue to be as such actions are considered in a larger social context. We may also define intervention and coercion differently depending on where we fall on the political spectrum. Considering the social implications of an individual action highlights another limitation of utilitarianism, and one that perhaps makes more sense to us than it would to Bentham and Mill, namely, that it makes no provision for emotional or cognitive harm. If the harm is not measurable in physical terms, then it lacks significance. For example, if a reckless driver today irresponsibly exceeds the speed limit, crashes into a concrete abutment, and kills himself while totaling his vehicle (which he owns), utilitarianism would hold that in the absence of physical harm to others, no one suffers except the driver. We may not arrive at the same conclusion. Instead, we might hold that the driver’s survivors and friends, along with society as a whole, have suffered a loss. Arguably, all of us are diminished by the recklessness of his act. Link to Learning Watch this video for a summary of utilitarian principles along with a literary example of a central problem of utility and an explanation of John Stuart Mill’s utilitarianism. The Role of Utilitarianism in Contemporary Business Utilitarianism is used frequently when business leaders make critical decisions about things like expansion, store closings, hiring, and layoffs. They do not necessarily refer to a “utilitarian calculus,” but whenever they take stock of what is to be gained and what might be lost in any significant decision (e.g., in a cost-benefit analysis), they make a utilitarian determination. At the same time, one might argue that a simple cost-benefits analysis is not a utilitarian calculus unless it includes consideration of all stakeholders and a full accounting of externalities, worker preferences, potentially coercive actions related to customers, or community and environmental effects. As a practical way of measuring value, Bentham’s system also plays a role in risk management. The utility function, or the potential for benefit or loss, can be translated into decision-making, risk assessment, and strategic planning. Together with data analytics, market evaluations, and financial projections, the utility function can provide managers with a tool for measuring the viability of prospective projects. It may even give them an opportunity to explore objections about the mechanistic and impractical nature of utilitarianism , especially from a customer perspective. Utilitarianism could motivate individuals within the organization to take initiative, become more responsible, and act in ways that enhance the organization’s reputation rather than tarnish it. Mill’s On Liberty ( Figure 2.8 ), a short treatment of political freedoms in tension with the power of the state, underscored the importance of expression and free speech, which Mill saw not as one right among many but as the foundational right, reflective of human nature, from which all others rights derive their meaning. And therein lay the greatest utility for society and business. For Mill, the path to utility led through truth, and the main way of arriving at truth was through a deliberative process that encouraged individual expression and the clash of ideas. As for Mill’s harm principle, the first question in trying to arrive at a business decision might be, does this action harm others? If the answer is yes, we must make a utilitarian calculation to decide whether there is still a greater good for the greatest number. Then we must ask, who are the others we must consider? All stakeholders? Only shareholders? What does harm entail, and who decides whether a proposed action might be harmful? This was the reason science and debate were so important to Mill, because the determination could not be left to public opinion or intuition. That was how tyranny started. By introducing deliberation, Mill was able to balance utility with freedom, which was a necessary condition for utility. Where Bentham looked to numerical formulas for determining value, relying on the objectivity of numbers, Mill sought value in reason and in the power of language to clarify where truth lies. The lesson for contemporary business, especially with the rise of big data, is that we need both numbers and reasoned principles. If we apply the Aristotelian and Confucian rule of the mean, we see that balance of responsibility and profitability makes the difference between sound business practices and poor ones. 2.5 Deontology: Ethics as Duty Learning Objectives By the end of this section, you will be able to: Explain Immanuel Kant’s concept of duty and the categorical imperative Differentiate between utilitarianism and deontology Apply a model of Kantian business ethics Unlike Bentham and Mill, Immanuel Kant (1724–1804) was not concerned with consequences of one’s actions or the harm caused to one’s individual interests. Instead, he focused on motives and the willingness of individuals to act for the good of others, even though that action might result in personal loss. Doing something for the right reason was much more important to Kant than any particular outcome. Aroused From “Dogmatic Slumber” In 1781, at the age of fifty-six years, Kant published Critique of Pure Reason ( Kritik der Reinen Vernunft ) in Königsberg, Prussia ( Figure 2.9 ). 51 Almost immediately, it transformed him from an obscure professor of metaphysics and logic into a preeminent figure in the world of philosophy. In the 800-page tome, Kant criticized the way rationalism (“pure reason”) had assumed the mantle of absolute truth, supplanting both religious faith and empirical science. Kant referred to the unquestioned acceptance of rationalism as dogmatism . Whether Christian or revolutionary, dogmatic thinking was to be avoided because it obscured the truths of science and religion through flawed logic. Kant credited the skepticism of empirical philosopher David Hume (1711–1776) with awakening him from “dogmatic slumber,” although he disagreed with Hume, who claimed that the mind did not exist at all but was the result of mental associations derived from sensory experience. 52 For Kant, reality could be discerned not through reasoning or sensory experience alone but only by understanding the nature of the human mind. Kant argued that sensory experience did not create the mind but rather that the mind created experience through its internal structures. And within the mind’s complex structures there also existed an inherent and unconditional duty to act ethically, which Kant called the “categorical imperative,” first outlined in Groundwork of the Metaphysic of Morals (1785). 53 In its initial form, Kant’s described his concept of the categorical imperative as follows: “Act only according to that maxim whereby you can, at the same time, will that it should become a universal law.” 54 Kant’s categorical (or unconditional) imperative has practical applications for the study of ethics. The categorical imperative contains two major suppositions: (1) We must act on the basis of goodwill rather than purely on self-interested motives that benefit ourselves at the expense of others; (2) we must never treat others as means toward ends benefitting ourselves without consideration of them also as ends in themselves. Kant held that observing the categorical imperative as we consider what actions to take would directly lead to ethical actions on our part. Link to Learning Watch this video about the categorical imperative to learn more. How do you see the imperative working in your own life? Within your family? In your personal and professional relationships? Does Kant’s understanding of the relationship between art and beauty accord with your own? In Kant’s view, rationalism and empiricism prevented people from perceiving the truth about their own nature. What was that truth? What was sufficient to constitute it? Kant identified an a priori world of knowledge and understanding in which truth lay in the structures and categories of the mind that were beyond perception and reason. This was a radical concept for the times. In the end, Kant’s systematic analysis of knowing and understanding provided a much-needed counterweight to the logic of Enlightenment rationalism. The existence of the mental structures he proposed has even been confirmed today. For instance, the scientific consensus is that humans are born with cognitive structures designed specifically for language acquisition and development. Even more surprising, there may be similar cognitive structures for morality, conscience, and moral decision-making. 55 So, it is quite possible that conscience, if not happiness, may have a genetic component after all, although Kant himself did not believe the categories of the understanding or the a priori structures of the mind were biological. Link to Learning Read a good survey of Kant’s critique of Enlightenment rationalism and of empiricism in this article. Utilitarianism and Deontology From a Kantian perspective, it is clear that adherence to duty is what builds the framework for ethical acts. This is in direct contradiction of Bentham’s view of human nature as selfish and requiring an objective calculus for ethical action to result. Kant rejected the idea of such a calculus and believed, instead, that perceptions were organized into preexisting categories or structures of the mind. Compare his notion of an ordered and purposeful universe of laws with the similar logos , or logic, of the ancient Greeks. One of those laws included implementation of the categorical imperative to act ethically, in accordance with our conscience. However, even though that imperative ought to be followed without exception, not everyone does so. In Kant’s moral teachings, individuals still had free will to accept or reject it. There is a definite contrast between utilitarianism, even Mill’s version, and Kant’s system of ethics, known as deontology , in which duty, obligation, and good will are of the highest importance. (The word is derived from the Greek deon , meaning duty, and logos again, here meaning organization for the purpose of study. 56 ) An ethical decision requires us to observe only the rights and duties we owe to others, and, in the context of business, act on the basis of a primary motive to do what is right by all stakeholders. Kant was not concerned with utility or outcome—his was not a system directed toward results. The question for him was not how to attain happiness but how to become worthy of it. Rather like Aristotle and Confucius, Kant taught that the transcendent aspects of human nature, if followed, would lead us inevitably to treat people as ends rather than means. To be moral meant to renounce uninformed dogmatism and rationalism, abide by the categorical imperative, and embrace freedom, moral sense, and even divinity. This was not a lofty or unattainable goal in Kant’s mind, because these virtues constituted part of the systematic structuring of the human mind. It could be accomplished by living truthfully or, as we say today, authentically. Such a feat transcended the logic of both rationalism and empiricism. What Would You Do? Les Misérables You may have seen the very popular Broadway show or movie Les Misérables , based on Victor Hugo’s epic nineteenth-century French novel of the same name. The main character, Jean Valjean, steals a loaf of bread to feed his sister’s starving family and is arrested and sent to prison. If we apply conventional reasoning and principles of law to his crime, Valjean genuinely is guilty as charged and we do not need to consider any extenuating circumstances. However, in a Kantian ethical framework, we would take into account Valjean’s motives as well as his duty to treat his sister’s family as ends in themselves who deserve to live. Valjean’s fate demonstrates what might occur when there is a gap between the legal and the moral. Clearly, Valjean broke the law by stealing the bread. However, he acted morally by correcting a wrong and possibly saving human lives. According to Kantian ethics, Valjean may have been ethical in stealing bread for his family, particularly because the action was grounded in good will and provided benefit to others more than to himself. Critical Thinking It has been said that in Kantian ethics, duty comes before beauty and morality before happiness. Can you think of other instances when it is appropriate to break one moral code to satisfy another, perhaps greater one? What are the deciding factors in each case? What would you do if you were Jean Valjean? Kantian Business Ethics Unlike utilitarianism, which forms the philosophical foundation for most cost-benefit analysis in business, Kantian ethics is not so easily applied. On one hand, it offers a unique opportunity for the development of individual morality through the categorical imperative to act ethically, which emphasizes humanity and autonomy. 57 This imperative addresses one major side of business ethics: the personal. Character and moral formation are crucial to creating an ethical culture. Indeed, business ethics is littered with cases of companies that have suffered damaging crises due to their leaders’ lack of commitment to act on the basis of a good will and with regard for what benefits others. Recent examples include Uber, where a toxic work environment was allowed to prevail, and Volkswagen, which knowingly misrepresented the emissions level of its cars. 58 Such examples exist in government as well, as the recent Theranos and “Fat Leonard” scandals confirm. 59 The latter consisted of graft and corruption in the U.S. Navy’s Pacific fleet and has been a continual source of embarrassment for an institution that prides itself on the honorable conduct of its officers. One person can make a difference, either positively or negatively. On the other hand, Kant’s categorical imperative is just that: categorical or unconditional. It calls for morally upright behavior regardless of external circumstance or the historical context of a proposed act or decision. Kant affirmed that “the moral law is an imperative, which commands categorically, because the law is unconditioned.” 60 Unconditional ethics could be a challenge for a global organization dealing with suppliers, customers, and competitors in sometimes vastly different cultures. It raises a larger philosophical issue: namely, was Kant correct in believing that morality and mental categories are independent of experience? Or can they be culturally conditioned, and, if so, does that make them relative rather than absolute, as Kant believed them to be? This question whether ethics is universal is distinctly Kantian, because Kant believed that not only must a moral agent act with others’ interests in mind and have the right intentions, but also that the action be universally applicable. Think of how Kantian ethics might be applied not just on an individual level but throughout an organization, and then society. Kant would judge a corporate act to be ethical if it benefitted others at the same time it benefitted company leadership and stockholders, and if it did not place their interests above those of other stakeholders. If loyalty to a coworker conflicted with loyalty to a supervisor or the organization, for instance, then acts resulting from such loyalty might not meet the conditions of deontology. Either the supervisor or the company would be treated as a means rather than an end. Although the qualitative or humanizing element of Kantian ethics has broad appeal, it runs into limitations in an actual business setting. Whether the limitations have good or bad effects depends on the organization’s culture and leadership. In general, however, most companies do not adhere to strict Kantian theories, because they look to the outcome of their decisions rather than focusing on motives or intentions. Cases from the Real World Samsung In the fall of 2016, Samsung Electronics experienced a massive public relations disaster when its Galaxy Note 7 smartphones started exploding due to faulty batteries and casings. Initially, the company denied there were any technical problems. Then, when it became obvious the exploding phones posed a safety and health threat (they were banned from airplanes), Samsung accused its suppliers of creating the problem. In reality, the rush to beat Apple’s iPhone 7 release date was the most likely reason corners were cut in production. Samsung finally owned up to the problem, recalled more than two million phones worldwide, and replaced them with new, improved Galaxy Note 7s. The company’s response and its replacement of the phones went a long way toward defusing the disaster and even boosting the company’s share price. Whether management knew it, its response was Kantian. Samsung focused on the end (i.e., customer safety and satisfaction) with the motive of doing the ethically responsible thing. Although some might argue the company could have done far more and much more quickly, perhaps it still acted in accordance with the categorical imperative. What do you think? Critical Thinking How might the categorical imperative become a part of organizational culture? Could it ever work in business? Do you see the categorical imperative as applicable to your own interests and hope for a career? 2.6 A Theory of Justice Learning Objectives By the end of this section, you will be able to: Evaluate John Rawls’s answer to utilitarianism Analyze the problem of redistribution Apply justice theory in a business context This chapter began with an image of Justice holding aloft scales as a symbol of equilibrium and fairness. It ends with an American political philosopher for whom the equal distribution of resources was a primary concern. John Rawls (1921–2002) wanted to change the debate that had prevailed throughout the 1960s and 1970s in the West about how to maximize wealth for everyone. He sought not to maximize wealth, which was a utilitarian goal, but to establish justice as the criterion by which goods and services were distributed among the populace. Justice, for Rawls, had to do with fairness—in fact, he frequently used the expression justice as fairness —and his concept of fairness was a political one that relied on the state to take care of the most disadvantaged. In his justice theory , offered as an alternative to the dominant utilitarianism of the times, the idea of fairness applied beyond the individual to include the community as well as analysis of social injustice with remedies to correct it. Justice Theory Rawls developed a theory of justice based on the Enlightenment ideas of thinkers like John Locke (1632–1704) and Jean-Jacques Rousseau (1712–1778), who advocated social contract theory . Social contract theory held that the natural state of human beings was freedom, but that human beings will rationally submit to some restrictions on their freedom to secure their mutual safety and benefit, not subjugation to a monarch, no matter how benign or well intentioned. This idea parallels that of Thomas Hobbes (1588–1679), who interpreted human nature to be selfish and brutish to the degree that, absent the strong hand of a ruler, chaos would result. So people willingly consent to transfer their autonomy to the control of a sovereign so their very lives and property will be secured. Rousseau rejected that view, as did Rawls, who expanded social contract theory to include justice as fairness. In A Theory of Justice (1971), Rawls introduced a universal system of fairness and a set of procedures for achieving it. He advocated a practical, empirically verifiable system of governance that would be political, social, and economic in its effects. Rawls’s justice theory contains three principles and five procedural steps for achieving fairness. The principles are (1) an “original position,” (2) a “veil of ignorance,” and (3) unanimity of acceptance of the original position. 61 By original position , Rawls meant something akin to Hobbes’ understanding of the state of nature, a hypothetical situation in which rational people can arrive at a contractual agreement about how resources are to be distributed in accordance with the principles of justice as fairness. This agreement was intended to reflect not present reality but a desired state of affairs among people in the community. The veil of ignorance ( Figure 2.10 ) is a condition in which people arrive at the original position imagining they have no identity regarding age, sex, ethnicity, education, income, physical attractiveness, or other characteristics. In this way, they reduce their bias and self-interest. Last, unanimity of acceptance is the requirement that all agree to the contract before it goes into effect. Rawls hoped this justice theory would provide a minimum guarantee of rights and liberties for everyone, because no one would know, until the veil was lifted, whether they were male, female, rich, poor, tall, short, intelligent, a minority, Roman Catholic, disabled, a veteran, and so on. The five procedural steps, or “conjectures,” are (1) entering into the contract, (2) agreeing unanimously to the contract, (3) including basic conditions in the contract such as freedom of speech, (4) maximizing the welfare of the most disadvantaged persons, and (5) ensuring the stability of the contract. 62 These steps create a system of justice that Rawls believed gave fairness its proper place above utility and the bottom line. The steps also supported his belief in people’s instinctual drive for fairness and equitable treatment. Perhaps this is best seen in an educational setting, for example, the university. By matriculating, students enter into a contract that includes basic freedoms such as assembly and speech. Students at a disadvantage (e.g., those burdened with loans, jobs, or other financial constraints) are accommodated as well as possible. The contract between the university and students has proven to be stable over time, from generation to generation. This same procedure applies on a micro level to the experience in the classroom between an individual teacher and students. Over the past several decades—for better or worse—the course syllabus has assumed the role of a written contract expressing this relationship. Rawls gave an example of what he called “pure procedural justice” in which a cake is shared among several people. 63 By what agreement shall the cake be divided? Rawls determined that the best way to divide the cake is to have the person slicing the cake take the last piece. This will ensure that everyone gets an equal amount. What is important is an independent standard to determine what is just and a procedure for implementing it. 64 The Problem of Redistribution Part of Rawls’s critique of utilitarianism is that its utility calculus can lead to tyranny. If we define pleasure as that which is popular, the minority can suffer in terrible ways and the majority become mere numbers. This became clear in Mills’s attempt to humanize Bentham’s calculus. But Mills’s harm principle had just as bad an effect, for the opposite reason. It did not require anyone to give up anything if it had to be done through coercion or force. To extend Rawls’s cake example, if one person owned a bakery and another were starving, like Jean Valjean’s sister in Les Misérables , utilitarianism would force the baker to give up what he had to satisfy the starving person without taking into account whether the baker had greater debts, a sick spouse requiring medical treatment, or a child with educational loans; in other words, the context of the situation matters, as opposed to just the consequences. However, Mill’s utilitarianism, adhering to the harm principle, would leave the starving person to his or her own devices. At least he or she would have one slice of cake. This was the problem of distribution and redistribution that Rawls hoped to solve, not by calculating pleasure and pain, profit and loss, but by applying fairness as a normative value that would benefit individuals and society. 65 The problem with this approach is that justice theory is a radical, egalitarian form of liberalism in which redistribution of material goods and services occurs without regard for historical context or the presumption many share that it inherently is wrong to take the property legally acquired by one and distribute it to another. Rawls has been criticized for promoting the same kind of coercion that can exist in utilitarianism but on the basis of justice rather than pleasure. Justice on a societal level would guarantee housing, education, medical treatment, food, and the basic necessities of life for everyone. Yet, as recent political campaigns have shown, the question of who will pay for these guaranteed goods and services through taxes is a contentious one. These are not merely fiscal and political issues; they are philosophical ones requiring us to answer questions of logic and, especially in the case of justice theory, fairness. And, naturally, we must ask, what is fair? Rawls’s principles and steps assume that the way in which the redistribution of goods and services occurs would be agreed upon by people in the community to avoid any fairness issues. But questions remain. For one, Rawls’s justice, like the iconic depiction, is blind and cannot see the circumstances in which goods and services are distributed. Second, we may question whether a notion of fairness is really innate. Third, despite the claim that justice theory is not consequentialist (meaning outcomes are not the only thing that matters), there is a coercive aspect to Rawls’s justice once the contract is in force, replacing utility with mandated fairness. Fourth, is this the kind of system in which people thrive and prosper, or, by focusing on the worst off, are initiative, innovation, and creativity dampened on the part of everyone else? Perhaps the most compelling critic of Rawls in this regard was his colleague at Harvard University, Robert Nozick (1938–2002), who wrote A Theory of Entitlement (1974) as a direct rebuttal of Rawlsian justice theory. 66 Nozick argued that the power of the state may never ethically be used to deprive someone of property he or she has legally obtained or inherited in order to distribute it to others who are in need of it. Still, one of the advantages of justice theory over the other ethical systems presented in this chapter is its emphasis on method as opposed to content. The system runs on a methodology or process for arriving at truth through the underlying value of fairness. Again, in this sense it is similar to utilitarianism, but, by requiring unanimity, it avoids the extremes of Bentham’s and Mill’s versions. As a method in ethics, it can be applied in a variety of ways and in multiple disciplines, because it can be adapted to just about any value-laden content. Of course, this raises the question of content versus method in ethics, especially because ethics has been defined as a set of cultural norms based on agreed-upon values. Method may be most effective in determining what those underlying values are, rather than how they are implemented. Link to Learning The “veil of ignorance” is a central concept in Rawls’s justice theory. What is it? What does it attempt to accomplish? Watch this video on how “ignorance can improve decision-making” to explore further. Justice in Business Although no ethical framework is perfect or fits a particular era completely, Rawls’s justice theory has distinct advantages when applied to business in the twenty-first century. First, as businesses become interdependent and globalized, they must pay more attention to quality control, human resources, and leadership in diverse settings. What will give greater legitimacy to an organization in these areas than fairness? Fairness is a value that is cross-cultural, embraced by different social groups, and understood by nearly everyone. However, what is considered fair depends on a variety of factors, including underlying values and individual characteristics like personality. For instance, not everyone agrees on whether or how diversity ought to be achieved. Neither is there consensus about affirmative action or the redistribution of resources or income. What is fair to some may be supremely unfair to others. This presents an opportunity for engaged debate and participation among the members of Rawls’s community. Second, as we saw earlier, justice theory provides a method for attaining fairness, which could make it a practical and valuable part of training at all levels of a company. The fact that its content—justice and fairness—is more accessible to contemporary people than Confucian virtue ethics and more flexible than Kant’s categorical imperative makes it an effective way of dealing with stakeholders and organizational culture. Justice theory may also provide a seamless way of engaging in corporate social responsibility outwardly and employee development inwardly. Fairness as a corporate doctrine can be applied to all stakeholders and define a culture of trust and openness, with all the corresponding benefits, in marketing, advertising, board development, client relations, and so on. It is also an effective way of integrating business ethics into the organization so ethics is no longer seen as the responsibility solely of the compliance department or legal team. Site leaders and middle managers understand fairness; employees probably even more so, because they are more directly affected by the lack of it. Fairness, then, is as much part of the job as it is an ongoing process of an ethics system. It no doubt makes for a happier and more productive workforce. An organization dedicated to it can also play a greater role in civic life and the political process, which, in turn, helps everyone. What Would You Do? John Rawls’s Thought Experiment John Rawls’s original position represents a community in which you have no idea what kind of person you will end up being. In this sense, it is like life itself. After all, you have no idea what your future will be like. You could end up rich, poor, married, single, living in Manhattan or Peru. You might be a surgeon or fishing for sturgeon. Yet, there is one community you will most likely be a part of at some point: the aged. Given that you know this but are not sure of the details, which conditions would you agree to now so that senior citizens are provided for? Remember that you most likely will join them and experience the effects of what you decide now. You are living behind not a spatial veil of ignorance but a temporal one. Critical Thinking What are you willing to give up so that seniors—whoever they might be—are afforded care and security in their later years? Should you have to pay into a system that provides medical coverage to other people less health conscious than you? Why or why not?
biology
Chapter Outline 3.1 Synthesis of Biological Macromolecules 3.2 Carbohydrates 3.3 Lipids 3.4 Proteins 3.5 Nucleic Acids Introduction Food provides the body with the nutrients it needs to survive. Many of these critical nutrients are biological macromolecules, or large molecules, necessary for life. These macromolecules (polymers) are built from different combinations of smaller organic molecules (monomers). What specific types of biological macromolecules do living things require? How are these molecules formed? What functions do they serve? In this chapter, these questions will be explored.
[ { "answer": { "ans_choice": 2, "ans_text": "water and polymers" }, "bloom": null, "hl_context": "Most macromolecules are made from single subunits , or building blocks , called monomers . <hl> The monomers combine with each other using covalent bonds to form larger molecules known as polymers . <hl> <hl> In doing so , monomers release water molecules as byproducts . <hl> <hl> This type of reaction is known as dehydration synthesis , which means “ to put together while losing water . ” <hl>", "hl_sentences": "The monomers combine with each other using covalent bonds to form larger molecules known as polymers . In doing so , monomers release water molecules as byproducts . This type of reaction is known as dehydration synthesis , which means “ to put together while losing water . ”", "question": { "cloze_format": "Dehydration synthesis leads to formation of ___ .", "normal_format": "What formation does the dehydration synthesis lead to?", "question_choices": [ "monomers", "polymers", "water and polymers", "none of the above" ], "question_id": "fs-id1313020", "question_text": "Dehydration synthesis leads to formation of" }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 0, "ans_text": "hydrolysis" }, "bloom": "1", "hl_context": "<hl> Polymers are broken down into monomers in a process known as hydrolysis , which means “ to split water , ” a reaction in which a water molecule is used during the breakdown ( Figure 3.3 ) . <hl> During these reactions , the polymer is broken into two components : one part gains a hydrogen atom ( H + ) and the other gains a hydroxyl molecule ( OH – ) from a split water molecule .", "hl_sentences": "Polymers are broken down into monomers in a process known as hydrolysis , which means “ to split water , ” a reaction in which a water molecule is used during the breakdown ( Figure 3.3 ) .", "question": { "cloze_format": "During the breakdown of polymers, the reaction ___ takes place.", "normal_format": "During the breakdown of polymers, which of the following reactions takes place?", "question_choices": [ "hydrolysis", "dehydration", "condensation", "covalent bond" ], "question_id": "fs-id1342364", "question_text": "During the breakdown of polymers, which of the following reactions takes place?" }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 3, "ans_text": "all of the above" }, "bloom": null, "hl_context": "<hl> Glucose , galactose , and fructose are isomeric monosaccharides ( hexoses ) , meaning they have the same chemical formula but have slightly different structures . <hl> Glucose and galactose are aldoses , and fructose is a ketose .", "hl_sentences": "Glucose , galactose , and fructose are isomeric monosaccharides ( hexoses ) , meaning they have the same chemical formula but have slightly different structures .", "question": { "cloze_format": "An example of a monosaccharide is ________.", "normal_format": "What is an example of a monosaccharide? ", "question_choices": [ "fructose", "glucose", "galactose", "all of the above" ], "question_id": "fs-id2310536", "question_text": "An example of a monosaccharide is ________." }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 3, "ans_text": "polysaccharides" }, "bloom": null, "hl_context": "Polysaccharides A long chain of monosaccharides linked by glycosidic bonds is known as a polysaccharide ( poly - = “ many ” ) . The chain may be branched or unbranched , and it may contain different types of monosaccharides . The molecular weight may be 100,000 daltons or more depending on the number of monomers joined . <hl> Starch , glycogen , cellulose , and chitin are primary examples of polysaccharides . <hl>", "hl_sentences": "Starch , glycogen , cellulose , and chitin are primary examples of polysaccharides .", "question": { "cloze_format": "Cellulose and starch are examples of ___.", "normal_format": "What are Cellulose and starch examples of?", "question_choices": [ "monosaccharides", "disaccharides", "lipids", "polysaccharides" ], "question_id": "fs-id1352111", "question_text": "Cellulose and starch are examples of:" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 1, "ans_text": "cellulose" }, "bloom": "1", "hl_context": "<hl> As shown in Figure 3.10 , every other glucose monomer in cellulose is flipped over , and the monomers are packed tightly as extended long chains . <hl> <hl> This gives cellulose its rigidity and high tensile strength — which is so important to plant cells . <hl> While the β 1-4 linkage cannot be broken down by human digestive enzymes , herbivores such as cows , koalas , and buffalos are able , with the help of the specialized flora in their stomach , to digest plant material that is rich in cellulose and use it as a food source . In these animals , certain species of bacteria and protists reside in the rumen ( part of the digestive system of herbivores ) and secrete the enzyme cellulase . The appendix of grazing animals also contains bacteria that digest cellulose , giving it an important role in the digestive systems of ruminants . Cellulases can break down cellulose into glucose monomers that can be used as an energy source by the animal . Termites are also able to break down cellulose because of the presence of other organisms in their bodies that secrete cellulases . Carbohydrates serve various functions in different animals . Arthropods ( insects , crustaceans , and others ) have an outer skeleton , called the exoskeleton , which protects their internal body parts ( as seen in the bee in Figure 3.11 ) . This exoskeleton is made of the biological macromolecule chitin , which is a polysaccharide-containing nitrogen . It is made of repeating units of N-acetyl - β - d-glucosamine , a modified sugar . Chitin is also a major component of fungal cell walls ; fungi are neither animals nor plants and form a kingdom of their own in the domain Eukarya . <hl> Cellulose is the most abundant natural biopolymer . <hl> <hl> The cell wall of plants is mostly made of cellulose ; this provides structural support to the cell . <hl> Wood and paper are mostly cellulosic in nature . Cellulose is made up of glucose monomers that are linked by β 1-4 glycosidic bonds ( Figure 3.10 ) .", "hl_sentences": "As shown in Figure 3.10 , every other glucose monomer in cellulose is flipped over , and the monomers are packed tightly as extended long chains . This gives cellulose its rigidity and high tensile strength — which is so important to plant cells . Cellulose is the most abundant natural biopolymer . The cell wall of plants is mostly made of cellulose ; this provides structural support to the cell .", "question": { "cloze_format": "Plant cell walls contain ___ in abundance.", "normal_format": "Plant cell walls contain which of the following in abundance?", "question_choices": [ "starch", "cellulose", "glycogen", "lactose" ], "question_id": "fs-id1730970", "question_text": "Plant cell walls contain which of the following in abundance?" }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 1, "ans_text": "glycosidic; galactose" }, "bloom": null, "hl_context": "Common disaccharides include lactose , maltose , and sucrose ( Figure 3.8 ) . <hl> Lactose is a disaccharide consisting of the monomers glucose and galactose . <hl> It is found naturally in milk . Maltose , or malt sugar , is a disaccharide formed by a dehydration reaction between two glucose molecules . The most common disaccharide is sucrose , or table sugar , which is composed of the monomers glucose and fructose . Disaccharides ( di - = “ two ” ) form when two monosaccharides undergo a dehydration reaction ( also known as a condensation reaction or dehydration synthesis ) . During this process , the hydroxyl group of one monosaccharide combines with the hydrogen of another monosaccharide , releasing a molecule of water and forming a covalent bond . <hl> A covalent bond formed between a carbohydrate molecule and another molecule ( in this case , between two monosaccharides ) is known as a glycosidic bond ( Figure 3.7 ) . <hl> Glycosidic bonds ( also called glycosidic linkages ) can be of the alpha or the beta type .", "hl_sentences": "Lactose is a disaccharide consisting of the monomers glucose and galactose . A covalent bond formed between a carbohydrate molecule and another molecule ( in this case , between two monosaccharides ) is known as a glycosidic bond ( Figure 3.7 ) .", "question": { "cloze_format": "Lactose is a disaccharide formed by the formation of a ________ bond between glucose and ________.", "normal_format": "Lactose is a disaccharide formed by the formation of what bond? And between glucose and what?", "question_choices": [ "glycosidic; lactose", "glycosidic; galactose", "hydrogen; sucrose", "hydrogen; fructose" ], "question_id": "fs-id1478280", "question_text": "Lactose is a disaccharide formed by the formation of a ________ bond between glucose and ________." }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 3, "ans_text": "they tend to dissolve in water easily" }, "bloom": null, "hl_context": "<hl> When a fatty acid has no double bonds , it is known as a saturated fatty acid because no more hydrogen may be added to the carbon atoms of the chain . <hl> A fat may contain similar or different fatty acids attached to glycerol . Long straight fatty acids with single bonds tend to get packed tightly and are solid at room temperature . Animal fats with stearic acid and palmitic acid ( common in meat ) and the fat with butyric acid ( common in butter ) are examples of saturated fats . Mammals store fats in specialized cells called adipocytes , where globules of fat occupy most of the cell ’ s volume . In plants , fat or oil is stored in many seeds and is used as a source of energy during seedling development . <hl> Unsaturated fats or oils are usually of plant origin and contain cis unsaturated fatty acids . <hl> Cis and trans indicate the configuration of the molecule around the double bond . <hl> If hydrogens are present in the same plane , it is referred to as a cis fat ; if the hydrogen atoms are on two different planes , it is referred to as a trans fat . <hl> <hl> The cis double bond causes a bend or a “ kink ” that prevents the fatty acids from packing tightly , keeping them liquid at room temperature ( Figure 3.16 ) . <hl> Olive oil , corn oil , canola oil , and cod liver oil are examples of unsaturated fats . Unsaturated fats help to lower blood cholesterol levels whereas saturated fats contribute to plaque formation in the arteries . Trans Fats", "hl_sentences": "When a fatty acid has no double bonds , it is known as a saturated fatty acid because no more hydrogen may be added to the carbon atoms of the chain . Unsaturated fats or oils are usually of plant origin and contain cis unsaturated fatty acids . If hydrogens are present in the same plane , it is referred to as a cis fat ; if the hydrogen atoms are on two different planes , it is referred to as a trans fat . The cis double bond causes a bend or a “ kink ” that prevents the fatty acids from packing tightly , keeping them liquid at room temperature ( Figure 3.16 ) .", "question": { "cloze_format": "Saturated fats have all of the following characteristics except ___\n", "normal_format": "Saturated fats have all of the following characteristics except which one?", "question_choices": [ "they are solid at room temperature", "they have single bonds within the carbon chain", "they are usually obtained from animal sources", "they tend to dissolve in water easily" ], "question_id": "fs-id1292143", "question_text": "Saturated fats have all of the following characteristics except:" }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 0, "ans_text": "the plasma membrane of animal cells" }, "bloom": "1", "hl_context": "Cholesterol is the most common steroid . Cholesterol is mainly synthesized in the liver and is the precursor to many steroid hormones such as testosterone and estradiol , which are secreted by the gonads and endocrine glands . It is also the precursor to Vitamin D . Cholesterol is also the precursor of bile salts , which help in the emulsification of fats and their subsequent absorption by cells . Although cholesterol is often spoken of in negative terms by lay people , it is necessary for proper functioning of the body . <hl> It is a component of the plasma membrane of animal cells and is found within the phospholipid bilayer . <hl> Being the outermost structure in animal cells , the plasma membrane is responsible for the transport of materials and cellular recognition and it is involved in cell-to-cell communication . <hl> Phospholipids are responsible for the dynamic nature of the plasma membrane . <hl> If a drop of phospholipids is placed in water , it spontaneously forms a structure known as a micelle , where the hydrophilic phosphate heads face the outside and the fatty acids face the interior of this structure . <hl> Phospholipids are major constituents of the plasma membrane , the outermost layer of animal cells . <hl> Like fats , they are composed of fatty acid chains attached to a glycerol or sphingosine backbone . Instead of three fatty acids attached as in triglycerides , however , there are two fatty acids forming diacylglycerol , and the third carbon of the glycerol backbone is occupied by a modified phosphate group ( Figure 3.19 ) . A phosphate group alone attached to a diaglycerol does not qualify as a phospholipid ; it is phosphatidate ( diacylglycerol 3 - phosphate ) , the precursor of phospholipids . The phosphate group is modified by an alcohol . Phosphatidylcholine and phosphatidylserine are two important phospholipids that are found in plasma membranes .", "hl_sentences": "It is a component of the plasma membrane of animal cells and is found within the phospholipid bilayer . Phospholipids are responsible for the dynamic nature of the plasma membrane . Phospholipids are major constituents of the plasma membrane , the outermost layer of animal cells .", "question": { "cloze_format": "Phospholipids are important components of ________.", "normal_format": "What are phospholids important components of?", "question_choices": [ "the plasma membrane of animal cells", "the ring structure of steroids", "the waxy covering on leaves", "the double bond in hydrocarbon chains" ], "question_id": "fs-id1407667", "question_text": "Phospholipids are important components of ________." }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 2, "ans_text": "amino acids" }, "bloom": null, "hl_context": "<hl> Amino acids are the monomers that make up proteins . <hl> Each amino acid has the same fundamental structure , which consists of a central carbon atom , also known as the alpha ( α ) carbon , bonded to an amino group ( NH 2 ) , a carboxyl group ( COOH ) , and to a hydrogen atom . Every amino acid also has another atom or group of atoms bonded to the central atom known as the R group ( Figure 3.22 ) .", "hl_sentences": "Amino acids are the monomers that make up proteins .", "question": { "cloze_format": "The monomers that make up proteins are called ________.", "normal_format": "What are the monomers that make up proteins?", "question_choices": [ "nucleotides", "disaccharides", "amino acids", "chaperones" ], "question_id": "fs-id2385460", "question_text": "The monomers that make up proteins are called ________." }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 1, "ans_text": "secondary" }, "bloom": "1", "hl_context": "<hl> The local folding of the polypeptide in some regions gives rise to the secondary structure of the protein . <hl> <hl> The most common are the α - helix and β - pleated sheet structures ( Figure 3.28 ) . <hl> Both structures are the α - helix structure — the helix held in shape by hydrogen bonds . The hydrogen bonds form between the oxygen atom in the carbonyl group in one amino acid and another amino acid that is four amino acids farther along the chain . Every helical turn in an alpha helix has 3.6 amino acid residues . The R groups ( the variant groups ) of the polypeptide protrude out from the α - helix chain . In the β - pleated sheet , the “ pleats ” are formed by hydrogen bonding between atoms on the backbone of the polypeptide chain . The R groups are attached to the carbons and extend above and below the folds of the pleat . The pleated segments align parallel or antiparallel to each other , and hydrogen bonds form between the partially positive nitrogen atom in the amino group and the partially negative oxygen atom in the carbonyl group of the peptide backbone . The α - helix and β - pleated sheet structures are found in most globular and fibrous proteins and they play an important structural role .", "hl_sentences": "The local folding of the polypeptide in some regions gives rise to the secondary structure of the protein . The most common are the α - helix and β - pleated sheet structures ( Figure 3.28 ) .", "question": { "cloze_format": "The α helix and the β-pleated sheet are part of the ___ protein structure.", "normal_format": "The α helix and the β-pleated sheet are part of which protein structure?", "question_choices": [ "primary", "secondary", "tertiary", "quaternary" ], "question_id": "fs-id1837286", "question_text": "The α helix and the β-pleated sheet are part of which protein structure?" }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 2, "ans_text": "deoxyribose, thymine, and a phosphate group" }, "bloom": null, "hl_context": "Adenine and guanine are classified as purines . The primary structure of a purine is two carbon-nitrogen rings . Cytosine , thymine , and uracil are classified as pyrimidines which have a single carbon-nitrogen ring as their primary structure ( Figure 3.31 ) . Each of these basic carbon-nitrogen rings has different functional groups attached to it . <hl> In molecular biology shorthand , the nitrogenous bases are simply known by their symbols A , T , G , C , and U . DNA contains A , T , G , and C whereas RNA contains A , U , G , and C . The pentose sugar in DNA is deoxyribose , and in RNA , the sugar is ribose ( Figure 3.31 ) . <hl> The difference between the sugars is the presence of the hydroxyl group on the second carbon of the ribose and hydrogen on the second carbon of the deoxyribose . The carbon atoms of the sugar molecule are numbered as 1 ′ , 2 ′ , 3 ′ , 4 ′ , and 5 ′ ( 1 ′ is read as “ one prime ” ) . The phosphate residue is attached to the hydroxyl group of the 5 ′ carbon of one sugar and the hydroxyl group of the 3 ′ carbon of the sugar of the next nucleotide , which forms a 5 ′ – 3 ′ phosphodiester linkage . The phosphodiester linkage is not formed by simple dehydration reaction like the other linkages connecting monomers in macromolecules : its formation involves the removal of two phosphate groups . A polynucleotide may have thousands of such phosphodiester linkages . DNA and RNA are made up of monomers known as nucleotides . The nucleotides combine with each other to form a polynucleotide , DNA or RNA . <hl> Each nucleotide is made up of three components : a nitrogenous base , a pentose ( five-carbon ) sugar , and a phosphate group ( Figure 3.31 ) . <hl> Each nitrogenous base in a nucleotide is attached to a sugar molecule , which is attached to one or more phosphate groups . The nitrogenous bases , important components of nucleotides , are organic molecules and are so named because they contain carbon and nitrogen . They are bases because they contain an amino group that has the potential of binding an extra hydrogen , and thus , decreases the hydrogen ion concentration in its environment , making it more basic . Each nucleotide in DNA contains one of four possible nitrogenous bases : adenine ( A ) , guanine ( G ) cytosine ( C ) , and thymine ( T ) .", "hl_sentences": "In molecular biology shorthand , the nitrogenous bases are simply known by their symbols A , T , G , C , and U . DNA contains A , T , G , and C whereas RNA contains A , U , G , and C . The pentose sugar in DNA is deoxyribose , and in RNA , the sugar is ribose ( Figure 3.31 ) . Each nucleotide is made up of three components : a nitrogenous base , a pentose ( five-carbon ) sugar , and a phosphate group ( Figure 3.31 ) .", "question": { "cloze_format": "A nucleotide of DNA may contain ________.", "normal_format": "What may a nucleotide of DNA contain?", "question_choices": [ "ribose, uracil, and a phosphate group", "deoxyribose, uracil, and a phosphate group", "deoxyribose, thymine, and a phosphate group", "ribose, thymine, and a phosphate group" ], "question_id": "fs-id2024549", "question_text": "A nucleotide of DNA may contain ________." }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 3, "ans_text": "nucleotides" }, "bloom": null, "hl_context": "<hl> DNA and RNA are made up of monomers known as nucleotides . <hl> The nucleotides combine with each other to form a polynucleotide , DNA or RNA . Each nucleotide is made up of three components : a nitrogenous base , a pentose ( five-carbon ) sugar , and a phosphate group ( Figure 3.31 ) . Each nitrogenous base in a nucleotide is attached to a sugar molecule , which is attached to one or more phosphate groups . The nitrogenous bases , important components of nucleotides , are organic molecules and are so named because they contain carbon and nitrogen . They are bases because they contain an amino group that has the potential of binding an extra hydrogen , and thus , decreases the hydrogen ion concentration in its environment , making it more basic . Each nucleotide in DNA contains one of four possible nitrogenous bases : adenine ( A ) , guanine ( G ) cytosine ( C ) , and thymine ( T ) .", "hl_sentences": "DNA and RNA are made up of monomers known as nucleotides .", "question": { "cloze_format": "The building blocks of nucleic acids are ________.", "normal_format": "What are the building blocks of nucleic acids?", "question_choices": [ "sugars", "nitrogenous bases", "peptides", "nucleotides" ], "question_id": "fs-id2081310", "question_text": "The building blocks of nucleic acids are ________." }, "references_are_paraphrase": 0 } ]
3
3.1 Synthesis of Biological Macromolecules Learning Objectives By the end of this section, you will be able to: Understand the synthesis of macromolecules Explain dehydration (or condensation) and hydrolysis reactions As you’ve learned, biological macromolecules are large molecules, necessary for life, that are built from smaller organic molecules. There are four major classes of biological macromolecules (carbohydrates, lipids, proteins, and nucleic acids); each is an important cell component and performs a wide array of functions. Combined, these molecules make up the majority of a cell’s dry mass (recall that water makes up the majority of its complete mass). Biological macromolecules are organic, meaning they contain carbon. In addition, they may contain hydrogen, oxygen, nitrogen, and additional minor elements. Dehydration Synthesis Most macromolecules are made from single subunits, or building blocks, called monomers . The monomers combine with each other using covalent bonds to form larger molecules known as polymers . In doing so, monomers release water molecules as byproducts. This type of reaction is known as dehydration synthesis , which means “to put together while losing water.” In a dehydration synthesis reaction ( Figure 3.2 ), the hydrogen of one monomer combines with the hydroxyl group of another monomer, releasing a molecule of water. At the same time, the monomers share electrons and form covalent bonds. As additional monomers join, this chain of repeating monomers forms a polymer. Different types of monomers can combine in many configurations, giving rise to a diverse group of macromolecules. Even one kind of monomer can combine in a variety of ways to form several different polymers: for example, glucose monomers are the constituents of starch, glycogen, and cellulose. Hydrolysis Polymers are broken down into monomers in a process known as hydrolysis, which means “to split water,” a reaction in which a water molecule is used during the breakdown ( Figure 3.3 ). During these reactions, the polymer is broken into two components: one part gains a hydrogen atom (H+) and the other gains a hydroxyl molecule (OH–) from a split water molecule. Dehydration and hydrolysis reactions are catalyzed, or “sped up,” by specific enzymes; dehydration reactions involve the formation of new bonds, requiring energy, while hydrolysis reactions break bonds and release energy. These reactions are similar for most macromolecules, but each monomer and polymer reaction is specific for its class. For example, in our bodies, food is hydrolyzed, or broken down, into smaller molecules by catalytic enzymes in the digestive system. This allows for easy absorption of nutrients by cells in the intestine. Each macromolecule is broken down by a specific enzyme. For instance, carbohydrates are broken down by amylase, sucrase, lactase, or maltase. Proteins are broken down by the enzymes pepsin and peptidase, and by hydrochloric acid. Lipids are broken down by lipases. Breakdown of these macromolecules provides energy for cellular activities. Link to Learning Visit this site to see visual representations of dehydration synthesis and hydrolysis. 3.2 Carbohydrates Learning Objectives By the end of this section, you will be able to: Discuss the role of carbohydrates in cells and in the extracellular materials of animals and plants Explain the classifications of carbohydrates List common monosaccharides, disaccharides, and polysaccharides Most people are familiar with carbohydrates, one type of macromolecule, especially when it comes to what we eat. To lose weight, some individuals adhere to “low-carb” diets. Athletes, in contrast, often “carb-load” before important competitions to ensure that they have enough energy to compete at a high level. Carbohydrates are, in fact, an essential part of our diet; grains, fruits, and vegetables are all natural sources of carbohydrates. Carbohydrates provide energy to the body, particularly through glucose, a simple sugar that is a component of starch and an ingredient in many staple foods. Carbohydrates also have other important functions in humans, animals, and plants. Molecular Structures Carbohydrates can be represented by the stoichiometric formula (CH 2 O) n , where n is the number of carbons in the molecule. In other words, the ratio of carbon to hydrogen to oxygen is 1:2:1 in carbohydrate molecules. This formula also explains the origin of the term “carbohydrate”: the components are carbon (“carbo”) and the components of water (hence, “hydrate”). Carbohydrates are classified into three subtypes: monosaccharides, disaccharides, and polysaccharides. Monosaccharides Monosaccharides (mono- = “one”; sacchar- = “sweet”) are simple sugars, the most common of which is glucose. In monosaccharides, the number of carbons usually ranges from three to seven. Most monosaccharide names end with the suffix -ose. If the sugar has an aldehyde group (the functional group with the structure R-CHO), it is known as an aldose, and if it has a ketone group (the functional group with the structure RC(=O)R'), it is known as a ketose. Depending on the number of carbons in the sugar, they also may be known as trioses (three carbons), pentoses (five carbons), and or hexoses (six carbons). See Figure 3.4 for an illustration of the monosaccharides. The chemical formula for glucose is C 6 H 12 O 6 . In humans, glucose is an important source of energy. During cellular respiration, energy is released from glucose, and that energy is used to help make adenosine triphosphate (ATP). Plants synthesize glucose using carbon dioxide and water, and glucose in turn is used for energy requirements for the plant. Excess glucose is often stored as starch that is catabolized (the breakdown of larger molecules by cells) by humans and other animals that feed on plants. Galactose (part of lactose, or milk sugar) and fructose (found in sucrose, in fruit) are other common monosaccharides. Although glucose, galactose, and fructose all have the same chemical formula (C 6 H 12 O 6 ), they differ structurally and chemically (and are known as isomers) because of the different arrangement of functional groups around the asymmetric carbon; all of these monosaccharides have more than one asymmetric carbon ( Figure 3.5 ). Visual Connection What kind of sugars are these, aldose or ketose? Glucose, galactose, and fructose are isomeric monosaccharides (hexoses), meaning they have the same chemical formula but have slightly different structures. Glucose and galactose are aldoses, and fructose is a ketose. Monosaccharides can exist as a linear chain or as ring-shaped molecules; in aqueous solutions they are usually found in ring forms ( Figure 3.6 ). Glucose in a ring form can have two different arrangements of the hydroxyl group (OH) around the anomeric carbon (carbon 1 that becomes asymmetric in the process of ring formation). If the hydroxyl group is below carbon number 1 in the sugar, it is said to be in the alpha ( α ) position, and if it is above the plane, it is said to be in the beta ( β ) position. Disaccharides Disaccharides (di- = “two”) form when two monosaccharides undergo a dehydration reaction (also known as a condensation reaction or dehydration synthesis). During this process, the hydroxyl group of one monosaccharide combines with the hydrogen of another monosaccharide, releasing a molecule of water and forming a covalent bond. A covalent bond formed between a carbohydrate molecule and another molecule (in this case, between two monosaccharides) is known as a glycosidic bond ( Figure 3.7 ). Glycosidic bonds (also called glycosidic linkages) can be of the alpha or the beta type. Common disaccharides include lactose, maltose, and sucrose ( Figure 3.8 ). Lactose is a disaccharide consisting of the monomers glucose and galactose. It is found naturally in milk. Maltose, or malt sugar, is a disaccharide formed by a dehydration reaction between two glucose molecules. The most common disaccharide is sucrose, or table sugar, which is composed of the monomers glucose and fructose. Polysaccharides A long chain of monosaccharides linked by glycosidic bonds is known as a polysaccharide (poly- = “many”). The chain may be branched or unbranched, and it may contain different types of monosaccharides. The molecular weight may be 100,000 daltons or more depending on the number of monomers joined. Starch, glycogen, cellulose, and chitin are primary examples of polysaccharides. Starch is the stored form of sugars in plants and is made up of a mixture of amylose and amylopectin (both polymers of glucose). Plants are able to synthesize glucose, and the excess glucose, beyond the plant’s immediate energy needs, is stored as starch in different plant parts, including roots and seeds. The starch in the seeds provides food for the embryo as it germinates and can also act as a source of food for humans and animals. The starch that is consumed by humans is broken down by enzymes, such as salivary amylases, into smaller molecules, such as maltose and glucose. The cells can then absorb the glucose. Starch is made up of glucose monomers that are joined by α 1-4 or α 1-6 glycosidic bonds. The numbers 1-4 and 1-6 refer to the carbon number of the two residues that have joined to form the bond. As illustrated in Figure 3.9 , amylose is starch formed by unbranched chains of glucose monomers (only α 1-4 linkages), whereas amylopectin is a branched polysaccharide ( α 1-6 linkages at the branch points). Glycogen is the storage form of glucose in humans and other vertebrates and is made up of monomers of glucose. Glycogen is the animal equivalent of starch and is a highly branched molecule usually stored in liver and muscle cells. Whenever blood glucose levels decrease, glycogen is broken down to release glucose in a process known as glycogenolysis. Cellulose is the most abundant natural biopolymer. The cell wall of plants is mostly made of cellulose; this provides structural support to the cell. Wood and paper are mostly cellulosic in nature. Cellulose is made up of glucose monomers that are linked by β 1-4 glycosidic bonds ( Figure 3.10 ). As shown in Figure 3.10 , every other glucose monomer in cellulose is flipped over, and the monomers are packed tightly as extended long chains. This gives cellulose its rigidity and high tensile strength—which is so important to plant cells. While the β 1-4 linkage cannot be broken down by human digestive enzymes, herbivores such as cows, koalas, and buffalos are able, with the help of the specialized flora in their stomach, to digest plant material that is rich in cellulose and use it as a food source. In these animals, certain species of bacteria and protists reside in the rumen (part of the digestive system of herbivores) and secrete the enzyme cellulase. The appendix of grazing animals also contains bacteria that digest cellulose, giving it an important role in the digestive systems of ruminants. Cellulases can break down cellulose into glucose monomers that can be used as an energy source by the animal. Termites are also able to break down cellulose because of the presence of other organisms in their bodies that secrete cellulases. Carbohydrates serve various functions in different animals. Arthropods (insects, crustaceans, and others) have an outer skeleton, called the exoskeleton, which protects their internal body parts (as seen in the bee in Figure 3.11 ). This exoskeleton is made of the biological macromolecule chitin , which is a polysaccharide-containing nitrogen. It is made of repeating units of N-acetyl- β -d-glucosamine, a modified sugar. Chitin is also a major component of fungal cell walls; fungi are neither animals nor plants and form a kingdom of their own in the domain Eukarya. Career Connection Registered Dietitian Obesity is a worldwide health concern, and many diseases such as diabetes and heart disease are becoming more prevalent because of obesity. This is one of the reasons why registered dietitians are increasingly sought after for advice. Registered dietitians help plan nutrition programs for individuals in various settings. They often work with patients in health care facilities, designing nutrition plans to treat and prevent diseases. For example, dietitians may teach a patient with diabetes how to manage blood sugar levels by eating the correct types and amounts of carbohydrates. Dietitians may also work in nursing homes, schools, and private practices. To become a registered dietitian, one needs to earn at least a bachelor’s degree in dietetics, nutrition, food technology, or a related field. In addition, registered dietitians must complete a supervised internship program and pass a national exam. Those who pursue careers in dietetics take courses in nutrition, chemistry, biochemistry, biology, microbiology, and human physiology. Dietitians must become experts in the chemistry and physiology (biological functions) of food (proteins, carbohydrates, and fats). Benefits of Carbohydrates Are carbohydrates good for you? People who wish to lose weight are often told that carbohydrates are bad for them and should be avoided. Some diets completely forbid carbohydrate consumption, claiming that a low-carbohydrate diet helps people to lose weight faster. However, carbohydrates have been an important part of the human diet for thousands of years; artifacts from ancient civilizations show the presence of wheat, rice, and corn in our ancestors’ storage areas. Carbohydrates should be supplemented with proteins, vitamins, and fats to be parts of a well-balanced diet. Calorie-wise, a gram of carbohydrate provides 4.3 Kcal. For comparison, fats provide 9 Kcal/g, a less desirable ratio. Carbohydrates contain soluble and insoluble elements; the insoluble part is known as fiber, which is mostly cellulose. Fiber has many uses; it promotes regular bowel movement by adding bulk, and it regulates the rate of consumption of blood glucose. Fiber also helps to remove excess cholesterol from the body: fiber binds to the cholesterol in the small intestine, then attaches to the cholesterol and prevents the cholesterol particles from entering the bloodstream, and then cholesterol exits the body via the feces. Fiber-rich diets also have a protective role in reducing the occurrence of colon cancer. In addition, a meal containing whole grains and vegetables gives a feeling of fullness. As an immediate source of energy, glucose is broken down during the process of cellular respiration, which produces ATP, the energy currency of the cell. Without the consumption of carbohydrates, the availability of “instant energy” would be reduced. Eliminating carbohydrates from the diet is not the best way to lose weight. A low-calorie diet that is rich in whole grains, fruits, vegetables, and lean meat, together with plenty of exercise and plenty of water, is the more sensible way to lose weight. Link to Learning For an additional perspective on carbohydrates, explore “Biomolecules: the Carbohydrates” through this interactive animation . 3.3 Lipids Learning Objectives By the end of this section, you will be able to: Describe the four major types of lipids Explain the role of fats in storing energy Differentiate between saturated and unsaturated fatty acids Describe phospholipids and their role in cells Define the basic structure of a steroid and some functions of steroids Explain the how cholesterol helps to maintain the fluid nature of the plasma membrane Lipids include a diverse group of compounds that are largely nonpolar in nature. This is because they are hydrocarbons that include mostly nonpolar carbon–carbon or carbon–hydrogen bonds. Non-polar molecules are hydrophobic (“water fearing”), or insoluble in water. Lipids perform many different functions in a cell. Cells store energy for long-term use in the form of fats. Lipids also provide insulation from the environment for plants and animals ( Figure 3.12 ). For example, they help keep aquatic birds and mammals dry when forming a protective layer over fur or feathers because of their water-repellant hydrophobic nature. Lipids are also the building blocks of many hormones and are an important constituent of all cellular membranes. Lipids include fats, oils, waxes, phospholipids, and steroids. Fats and Oils A fat molecule consists of two main components—glycerol and fatty acids. Glycerol is an organic compound (alcohol) with three carbons, five hydrogens, and three hydroxyl (OH) groups. Fatty acids have a long chain of hydrocarbons to which a carboxyl group is attached, hence the name “fatty acid.” The number of carbons in the fatty acid may range from 4 to 36; most common are those containing 12–18 carbons. In a fat molecule, the fatty acids are attached to each of the three carbons of the glycerol molecule with an ester bond through an oxygen atom ( Figure 3.13 ). During this ester bond formation, three water molecules are released. The three fatty acids in the triacylglycerol may be similar or dissimilar. Fats are also called triacylglycerols or triglycerides because of their chemical structure. Some fatty acids have common names that specify their origin. For example, palmitic acid, a saturated fatty acid , is derived from the palm tree. Arachidic acid is derived from Arachis hypogea, the scientific name for groundnuts or peanuts. Fatty acids may be saturated or unsaturated. In a fatty acid chain, if there are only single bonds between neighboring carbons in the hydrocarbon chain, the fatty acid is said to be saturated. Saturated fatty acids are saturated with hydrogen; in other words, the number of hydrogen atoms attached to the carbon skeleton is maximized. Stearic acid is an example of a saturated fatty acid ( Figure 3.14 ) When the hydrocarbon chain contains a double bond, the fatty acid is said to be unsaturated . Oleic acid is an example of an unsaturated fatty acid ( Figure 3.15 ). Most unsaturated fats are liquid at room temperature and are called oils. If there is one double bond in the molecule, then it is known as a monounsaturated fat (e.g., olive oil), and if there is more than one double bond, then it is known as a polyunsaturated fat (e.g., canola oil). When a fatty acid has no double bonds, it is known as a saturated fatty acid because no more hydrogen may be added to the carbon atoms of the chain. A fat may contain similar or different fatty acids attached to glycerol. Long straight fatty acids with single bonds tend to get packed tightly and are solid at room temperature. Animal fats with stearic acid and palmitic acid (common in meat) and the fat with butyric acid (common in butter) are examples of saturated fats. Mammals store fats in specialized cells called adipocytes, where globules of fat occupy most of the cell’s volume. In plants, fat or oil is stored in many seeds and is used as a source of energy during seedling development. Unsaturated fats or oils are usually of plant origin and contain cis unsaturated fatty acids. Cis and trans indicate the configuration of the molecule around the double bond. If hydrogens are present in the same plane, it is referred to as a cis fat; if the hydrogen atoms are on two different planes, it is referred to as a trans fat . The cis double bond causes a bend or a “kink” that prevents the fatty acids from packing tightly, keeping them liquid at room temperature ( Figure 3.16 ). Olive oil, corn oil, canola oil, and cod liver oil are examples of unsaturated fats. Unsaturated fats help to lower blood cholesterol levels whereas saturated fats contribute to plaque formation in the arteries. Trans Fats In the food industry, oils are artificially hydrogenated to make them semi-solid and of a consistency desirable for many processed food products. Simply speaking, hydrogen gas is bubbled through oils to solidify them. During this hydrogenation process, double bonds of the cis - conformation in the hydrocarbon chain may be converted to double bonds in the trans- conformation. Margarine, some types of peanut butter, and shortening are examples of artificially hydrogenated trans fats. Recent studies have shown that an increase in trans fats in the human diet may lead to an increase in levels of low-density lipoproteins (LDL), or “bad” cholesterol, which in turn may lead to plaque deposition in the arteries, resulting in heart disease. Many fast food restaurants have recently banned the use of trans fats, and food labels are required to display the trans fat content. Omega Fatty Acids Essential fatty acids are fatty acids required but not synthesized by the human body. Consequently, they have to be supplemented through ingestion via the diet. Omega -3 fatty acids (like that shown in Figure 3.17 ) fall into this category and are one of only two known for humans (the other being omega-6 fatty acid). These are polyunsaturated fatty acids and are called omega-3 because the third carbon from the end of the hydrocarbon chain is connected to its neighboring carbon by a double bond. The farthest carbon away from the carboxyl group is numbered as the omega ( ω ) carbon, and if the double bond is between the third and fourth carbon from that end, it is known as an omega-3 fatty acid. Nutritionally important because the body does not make them, omega-3 fatty acids include alpha-linoleic acid (ALA), eicosapentaenoic acid (EPA), and docosahexaenoic acid (DHA), all of which are polyunsaturated. Salmon, trout, and tuna are good sources of omega-3 fatty acids. Research indicates that omega-3 fatty acids reduce the risk of sudden death from heart attacks, reduce triglycerides in the blood, lower blood pressure, and prevent thrombosis by inhibiting blood clotting. They also reduce inflammation, and may help reduce the risk of some cancers in animals. Like carbohydrates, fats have received a lot of bad publicity. It is true that eating an excess of fried foods and other “fatty” foods leads to weight gain. However, fats do have important functions. Many vitamins are fat soluble, and fats serve as a long-term storage form of fatty acids: a source of energy. They also provide insulation for the body. Therefore, “healthy” fats in moderate amounts should be consumed on a regular basis. Waxes Wax covers the feathers of some aquatic birds and the leaf surfaces of some plants. Because of the hydrophobic nature of waxes, they prevent water from sticking on the surface ( Figure 3.18 ). Waxes are made up of long fatty acid chains esterified to long-chain alcohols. Phospholipids Phospholipids are major constituents of the plasma membrane, the outermost layer of animal cells. Like fats, they are composed of fatty acid chains attached to a glycerol or sphingosine backbone. Instead of three fatty acids attached as in triglycerides, however, there are two fatty acids forming diacylglycerol, and the third carbon of the glycerol backbone is occupied by a modified phosphate group ( Figure 3.19 ). A phosphate group alone attached to a diaglycerol does not qualify as a phospholipid; it is phosphatidate (diacylglycerol 3-phosphate), the precursor of phospholipids. The phosphate group is modified by an alcohol. Phosphatidylcholine and phosphatidylserine are two important phospholipids that are found in plasma membranes. A phospholipid is an amphipathic molecule, meaning it has a hydrophobic and a hydrophilic part. The fatty acid chains are hydrophobic and cannot interact with water, whereas the phosphate-containing group is hydrophilic and interacts with water ( Figure 3.20 ). The head is the hydrophilic part, and the tail contains the hydrophobic fatty acids. In a membrane, a bilayer of phospholipids forms the matrix of the structure, the fatty acid tails of phospholipids face inside, away from water, whereas the phosphate group faces the outside, aqueous side ( Figure 3.20 ). Phospholipids are responsible for the dynamic nature of the plasma membrane. If a drop of phospholipids is placed in water, it spontaneously forms a structure known as a micelle, where the hydrophilic phosphate heads face the outside and the fatty acids face the interior of this structure. Steroids Unlike the phospholipids and fats discussed earlier, steroids have a fused ring structure. Although they do not resemble the other lipids, they are grouped with them because they are also hydrophobic and insoluble in water. All steroids have four linked carbon rings and several of them, like cholesterol, have a short tail ( Figure 3.21 ). Many steroids also have the –OH functional group, which puts them in the alcohol classification (sterols). Cholesterol is the most common steroid. Cholesterol is mainly synthesized in the liver and is the precursor to many steroid hormones such as testosterone and estradiol, which are secreted by the gonads and endocrine glands. It is also the precursor to Vitamin D. Cholesterol is also the precursor of bile salts, which help in the emulsification of fats and their subsequent absorption by cells. Although cholesterol is often spoken of in negative terms by lay people, it is necessary for proper functioning of the body. It is a component of the plasma membrane of animal cells and is found within the phospholipid bilayer. Being the outermost structure in animal cells, the plasma membrane is responsible for the transport of materials and cellular recognition and it is involved in cell-to-cell communication. Link to Learning For an additional perspective on lipids, explore the interactive animation “Biomolecules: The Lipids” . 3.4 Proteins Learning Objectives By the end of this section, you will be able to: Describe the functions proteins perform in the cell and in tissues Discuss the relationship between amino acids and proteins Explain the four levels of protein organization Describe the ways in which protein shape and function are linked Proteins are one of the most abundant organic molecules in living systems and have the most diverse range of functions of all macromolecules. Proteins may be structural, regulatory, contractile, or protective; they may serve in transport, storage, or membranes; or they may be toxins or enzymes. Each cell in a living system may contain thousands of proteins, each with a unique function. Their structures, like their functions, vary greatly. They are all, however, polymers of amino acids, arranged in a linear sequence. Types and Functions of Proteins Enzymes , which are produced by living cells, are catalysts in biochemical reactions (like digestion) and are usually complex or conjugated proteins. Each enzyme is specific for the substrate (a reactant that binds to an enzyme) it acts on. The enzyme may help in breakdown, rearrangement, or synthesis reactions. Enzymes that break down their substrates are called catabolic enzymes, enzymes that build more complex molecules from their substrates are called anabolic enzymes, and enzymes that affect the rate of reaction are called catalytic enzymes. It should be noted that all enzymes increase the rate of reaction and, therefore, are considered to be organic catalysts. An example of an enzyme is salivary amylase, which hydrolyzes its substrate amylose, a component of starch. Hormones are chemical-signaling molecules, usually small proteins or steroids, secreted by endocrine cells that act to control or regulate specific physiological processes, including growth, development, metabolism, and reproduction. For example, insulin is a protein hormone that helps to regulate the blood glucose level. The primary types and functions of proteins are listed in Table 3.1 . Protein Types and Functions Type Examples Functions Digestive Enzymes Amylase, lipase, pepsin, trypsin Help in digestion of food by catabolizing nutrients into monomeric units Transport Hemoglobin, albumin Carry substances in the blood or lymph throughout the body Structural Actin, tubulin, keratin Construct different structures, like the cytoskeleton Hormones Insulin, thyroxine Coordinate the activity of different body systems Defense Immunoglobulins Protect the body from foreign pathogens Contractile Actin, myosin Effect muscle contraction Storage Legume storage proteins, egg white (albumin) Provide nourishment in early development of the embryo and the seedling Table 3.1 Proteins have different shapes and molecular weights; some proteins are globular in shape whereas others are fibrous in nature. For example, hemoglobin is a globular protein, but collagen, found in our skin, is a fibrous protein. Protein shape is critical to its function, and this shape is maintained by many different types of chemical bonds. Changes in temperature, pH, and exposure to chemicals may lead to permanent changes in the shape of the protein, leading to loss of function, known as denaturation . All proteins are made up of different arrangements of the same 20 types of amino acids. Amino Acids Amino acids are the monomers that make up proteins. Each amino acid has the same fundamental structure, which consists of a central carbon atom, also known as the alpha ( α ) carbon, bonded to an amino group (NH 2 ), a carboxyl group (COOH), and to a hydrogen atom. Every amino acid also has another atom or group of atoms bonded to the central atom known as the R group ( Figure 3.22 ). The name "amino acid" is derived from the fact that they contain both amino group and carboxyl-acid-group in their basic structure. As mentioned, there are 20 amino acids present in proteins. Nine of these are considered essential amino acids in humans because the human body cannot produce them and they are obtained from the diet. For each amino acid, the R group (or side chain) is different ( Figure 3.23 ). Art Connection Which categories of amino acid would you expect to find on the surface of a soluble protein, and which would you expect to find in the interior? What distribution of amino acids would you expect to find in a protein embedded in a lipid bilayer? The chemical nature of the side chain determines the nature of the amino acid (that is, whether it is acidic, basic, polar, or nonpolar). For example, the amino acid glycine has a hydrogen atom as the R group. Amino acids such as valine, methionine, and alanine are nonpolar or hydrophobic in nature, while amino acids such as serine, threonine, and cysteine are polar and have hydrophilic side chains. The side chains of lysine and arginine are positively charged, and therefore these amino acids are also known as basic amino acids. Proline has an R group that is linked to the amino group, forming a ring-like structure. Proline is an exception to the standard structure of an animo acid since its amino group is not separate from the side chain ( Figure 3.23 ). Amino acids are represented by a single upper case letter or a three-letter abbreviation. For example, valine is known by the letter V or the three-letter symbol val. Just as some fatty acids are essential to a diet, some amino acids are necessary as well. They are known as essential amino acids, and in humans they include isoleucine, leucine, and cysteine. Essential amino acids refer to those necessary for construction of proteins in the body, although not produced by the body; which amino acids are essential varies from organism to organism. The sequence and the number of amino acids ultimately determine the protein's shape, size, and function. Each amino acid is attached to another amino acid by a covalent bond, known as a peptide bond , which is formed by a dehydration reaction. The carboxyl group of one amino acid and the amino group of the incoming amino acid combine, releasing a molecule of water. The resulting bond is the peptide bond ( Figure 3.24 ). The products formed by such linkages are called peptides. As more amino acids join to this growing chain, the resulting chain is known as a polypeptide. Each polypeptide has a free amino group at one end. This end is called the N terminal, or the amino terminal, and the other end has a free carboxyl group, also known as the C or carboxyl terminal. While the terms polypeptide and protein are sometimes used interchangeably, a polypeptide is technically a polymer of amino acids, whereas the term protein is used for a polypeptide or polypeptides that have combined together, often have bound non-peptide prosthetic groups, have a distinct shape, and have a unique function. After protein synthesis (translation), most proteins are modified. These are known as post-translational modifications. They may undergo cleavage, phosphorylation, or may require the addition of other chemical groups. Only after these modifications is the protein completely functional. Link to Learning Click through the steps of protein synthesis in this interactive tutorial . Evolution Connection The Evolutionary Significance of Cytochrome c Cytochrome c is an important component of the electron transport chain, a part of cellular respiration, and it is normally found in the cellular organelle, the mitochondrion. This protein has a heme prosthetic group, and the central ion of the heme gets alternately reduced and oxidized during electron transfer. Because this essential protein’s role in producing cellular energy is crucial, it has changed very little over millions of years. Protein sequencing has shown that there is a considerable amount of cytochrome c amino acid sequence homology among different species; in other words, evolutionary kinship can be assessed by measuring the similarities or differences among various species’ DNA or protein sequences. Scientists have determined that human cytochrome c contains 104 amino acids. For each cytochrome c molecule from different organisms that has been sequenced to date, 37 of these amino acids appear in the same position in all samples of cytochrome c. This indicates that there may have been a common ancestor. On comparing the human and chimpanzee protein sequences, no sequence difference was found. When human and rhesus monkey sequences were compared, the single difference found was in one amino acid. In another comparison, human to yeast sequencing shows a difference in the 44th position. Protein Structure As discussed earlier, the shape of a protein is critical to its function. For example, an enzyme can bind to a specific substrate at a site known as the active site. If this active site is altered because of local changes or changes in overall protein structure, the enzyme may be unable to bind to the substrate. To understand how the protein gets its final shape or conformation, we need to understand the four levels of protein structure: primary, secondary, tertiary, and quaternary. Primary Structure The unique sequence of amino acids in a polypeptide chain is its primary structure . For example, the pancreatic hormone insulin has two polypeptide chains, A and B, and they are linked together by disulfide bonds. The N terminal amino acid of the A chain is glycine, whereas the C terminal amino acid is asparagine ( Figure 3.25 ). The sequences of amino acids in the A and B chains are unique to insulin. The unique sequence for every protein is ultimately determined by the gene encoding the protein. A change in nucleotide sequence of the gene’s coding region may lead to a different amino acid being added to the growing polypeptide chain, causing a change in protein structure and function. In sickle cell anemia, the hemoglobin β chain (a small portion of which is shown in Figure 3.26 ) has a single amino acid substitution, causing a change in protein structure and function. Specifically, the amino acid glutamic acid is substituted by valine in the β chain. What is most remarkable to consider is that a hemoglobin molecule is made up of two alpha chains and two beta chains that each consist of about 150 amino acids. The molecule, therefore, has about 600 amino acids. The structural difference between a normal hemoglobin molecule and a sickle cell molecule—which dramatically decreases life expectancy—is a single amino acid of the 600. What is even more remarkable is that those 600 amino acids are encoded by three nucleotides each, and the mutation is caused by a single base change (point mutation), 1 in 1800 bases. Because of this change of one amino acid in the chain, hemoglobin molecules form long fibers that distort the biconcave, or disc-shaped, red blood cells and assume a crescent or “sickle” shape, which clogs arteries ( Figure 3.27 ). This can lead to myriad serious health problems such as breathlessness, dizziness, headaches, and abdominal pain for those affected by this disease. Secondary Structure The local folding of the polypeptide in some regions gives rise to the secondary structure of the protein. The most common are the α -helix and β -pleated sheet structures ( Figure 3.28 ). Both structures are the α -helix structure—the helix held in shape by hydrogen bonds. The hydrogen bonds form between the oxygen atom in the carbonyl group in one amino acid and another amino acid that is four amino acids farther along the chain. Every helical turn in an alpha helix has 3.6 amino acid residues. The R groups (the variant groups) of the polypeptide protrude out from the α -helix chain. In the β -pleated sheet, the “pleats” are formed by hydrogen bonding between atoms on the backbone of the polypeptide chain. The R groups are attached to the carbons and extend above and below the folds of the pleat. The pleated segments align parallel or antiparallel to each other, and hydrogen bonds form between the partially positive nitrogen atom in the amino group and the partially negative oxygen atom in the carbonyl group of the peptide backbone. The α -helix and β -pleated sheet structures are found in most globular and fibrous proteins and they play an important structural role. Tertiary Structure The unique three-dimensional structure of a polypeptide is its tertiary structure ( Figure 3.29 ). This structure is in part due to chemical interactions at work on the polypeptide chain. Primarily, the interactions among R groups creates the complex three-dimensional tertiary structure of a protein. The nature of the R groups found in the amino acids involved can counteract the formation of the hydrogen bonds described for standard secondary structures. For example, R groups with like charges are repelled by each other and those with unlike charges are attracted to each other (ionic bonds). When protein folding takes place, the hydrophobic R groups of nonpolar amino acids lay in the interior of the protein, whereas the hydrophilic R groups lay on the outside. The former types of interactions are also known as hydrophobic interactions. Interaction between cysteine side chains forms disulfide linkages in the presence of oxygen, the only covalent bond forming during protein folding. All of these interactions, weak and strong, determine the final three-dimensional shape of the protein. When a protein loses its three-dimensional shape, it may no longer be functional. Quaternary Structure In nature, some proteins are formed from several polypeptides, also known as subunits, and the interaction of these subunits forms the quaternary structure . Weak interactions between the subunits help to stabilize the overall structure. For example, insulin (a globular protein) has a combination of hydrogen bonds and disulfide bonds that cause it to be mostly clumped into a ball shape. Insulin starts out as a single polypeptide and loses some internal sequences in the presence of post-translational modification after the formation of the disulfide linkages that hold the remaining chains together. Silk (a fibrous protein), however, has a β -pleated sheet structure that is the result of hydrogen bonding between different chains. The four levels of protein structure (primary, secondary, tertiary, and quaternary) are illustrated in Figure 3.30 . Denaturation and Protein Folding Each protein has its own unique sequence and shape that are held together by chemical interactions. If the protein is subject to changes in temperature, pH, or exposure to chemicals, the protein structure may change, losing its shape without losing its primary sequence in what is known as denaturation. Denaturation is often reversible because the primary structure of the polypeptide is conserved in the process if the denaturing agent is removed, allowing the protein to resume its function. Sometimes denaturation is irreversible, leading to loss of function. One example of irreversible protein denaturation is when an egg is fried. The albumin protein in the liquid egg white is denatured when placed in a hot pan. Not all proteins are denatured at high temperatures; for instance, bacteria that survive in hot springs have proteins that function at temperatures close to boiling. The stomach is also very acidic, has a low pH, and denatures proteins as part of the digestion process; however, the digestive enzymes of the stomach retain their activity under these conditions. Protein folding is critical to its function. It was originally thought that the proteins themselves were responsible for the folding process. Only recently was it found that often they receive assistance in the folding process from protein helpers known as chaperones (or chaperonins) that associate with the target protein during the folding process. They act by preventing aggregation of polypeptides that make up the complete protein structure, and they disassociate from the protein once the target protein is folded. Link to Learning For an additional perspective on proteins, view this animation called “Biomolecules: The Proteins.” 3.5 Nucleic Acids Learning Objectives By the end of this section, you will be able to: Describe the structure of nucleic acids and define the two types of nucleic acids Explain the structure and role of DNA Explain the structure and roles of RNA Nucleic acids are the most important macromolecules for the continuity of life. They carry the genetic blueprint of a cell and carry instructions for the functioning of the cell. DNA and RNA The two main types of nucleic acids are deoxyribonucleic acid (DNA) and ribonucleic acid (RNA) . DNA is the genetic material found in all living organisms, ranging from single-celled bacteria to multicellular mammals. It is found in the nucleus of eukaryotes and in the organelles, chloroplasts, and mitochondria. In prokaryotes, the DNA is not enclosed in a membranous envelope. The entire genetic content of a cell is known as its genome, and the study of genomes is genomics. In eukaryotic cells but not in prokaryotes, DNA forms a complex with histone proteins to form chromatin, the substance of eukaryotic chromosomes. A chromosome may contain tens of thousands of genes. Many genes contain the information to make protein products; other genes code for RNA products. DNA controls all of the cellular activities by turning the genes “on” or “off.” The other type of nucleic acid, RNA, is mostly involved in protein synthesis. The DNA molecules never leave the nucleus but instead use an intermediary to communicate with the rest of the cell. This intermediary is the messenger RNA (mRNA) . Other types of RNA—like rRNA, tRNA, and microRNA—are involved in protein synthesis and its regulation. DNA and RNA are made up of monomers known as nucleotides . The nucleotides combine with each other to form a polynucleotide , DNA or RNA. Each nucleotide is made up of three components: a nitrogenous base, a pentose (five-carbon) sugar, and a phosphate group ( Figure 3.31 ). Each nitrogenous base in a nucleotide is attached to a sugar molecule, which is attached to one or more phosphate groups. The nitrogenous bases, important components of nucleotides, are organic molecules and are so named because they contain carbon and nitrogen. They are bases because they contain an amino group that has the potential of binding an extra hydrogen, and thus, decreases the hydrogen ion concentration in its environment, making it more basic. Each nucleotide in DNA contains one of four possible nitrogenous bases: adenine (A), guanine (G) cytosine (C), and thymine (T). Adenine and guanine are classified as purines . The primary structure of a purine is two carbon-nitrogen rings. Cytosine, thymine, and uracil are classified as pyrimidines which have a single carbon-nitrogen ring as their primary structure ( Figure 3.31 ). Each of these basic carbon-nitrogen rings has different functional groups attached to it. In molecular biology shorthand, the nitrogenous bases are simply known by their symbols A, T, G, C, and U. DNA contains A, T, G, and C whereas RNA contains A, U, G, and C. The pentose sugar in DNA is deoxyribose, and in RNA, the sugar is ribose ( Figure 3.31 ). The difference between the sugars is the presence of the hydroxyl group on the second carbon of the ribose and hydrogen on the second carbon of the deoxyribose. The carbon atoms of the sugar molecule are numbered as 1′, 2′, 3′, 4′, and 5′ (1′ is read as “one prime”). The phosphate residue is attached to the hydroxyl group of the 5′ carbon of one sugar and the hydroxyl group of the 3′ carbon of the sugar of the next nucleotide, which forms a 5′–3′ phosphodiester linkage. The phosphodiester linkage is not formed by simple dehydration reaction like the other linkages connecting monomers in macromolecules: its formation involves the removal of two phosphate groups. A polynucleotide may have thousands of such phosphodiester linkages. DNA Double-Helix Structure DNA has a double-helix structure ( Figure 3.32 ). The sugar and phosphate lie on the outside of the helix, forming the backbone of the DNA. The nitrogenous bases are stacked in the interior, like the steps of a staircase, in pairs; the pairs are bound to each other by hydrogen bonds. Every base pair in the double helivx is separated from the next base pair by 0.34 nm. The two strands of the helix run in opposite directions, meaning that the 5′ carbon end of one strand will face the 3′ carbon end of its matching strand. (This is referred to as antiparallel orientation and is important to DNA replication and in many nucleic acid interactions.) Only certain types of base pairing are allowed. For example, a certain purine can only pair with a certain pyrimidine. This means A can pair with T, and G can pair with C, as shown in Figure 3.33 . This is known as the base complementary rule. In other words, the DNA strands are complementary to each other. If the sequence of one strand is AATTGGCC, the complementary strand would have the sequence TTAACCGG. During DNA replication, each strand is copied, resulting in a daughter DNA double helix containing one parental DNA strand and a newly synthesized strand. Art Connection A mutation occurs, and cytosine is replaced with adenine. What impact do you think this will have on the DNA structure? RNA Ribonucleic acid, or RNA, is mainly involved in the process of protein synthesis under the direction of DNA. RNA is usually single-stranded and is made of ribonucleotides that are linked by phosphodiester bonds. A ribonucleotide in the RNA chain contains ribose (the pentose sugar), one of the four nitrogenous bases (A, U, G, and C), and the phosphate group. There are four major types of RNA: messenger RNA (mRNA), ribosomal RNA (rRNA), transfer RNA (tRNA), and microRNA (miRNA). The first, mRNA, carries the message from DNA, which controls all of the cellular activities in a cell. If a cell requires a certain protein to be synthesized, the gene for this product is turned “on” and the messenger RNA is synthesized in the nucleus. The RNA base sequence is complementary to the coding sequence of the DNA from which it has been copied. However, in RNA, the base T is absent and U is present instead. If the DNA strand has a sequence AATTGCGC, the sequence of the complementary RNA is UUAACGCG. In the cytoplasm, the mRNA interacts with ribosomes and other cellular machinery ( Figure 3.34 ). The mRNA is read in sets of three bases known as codons. Each codon codes for a single amino acid. In this way, the mRNA is read and the protein product is made. Ribosomal RNA (rRNA) is a major constituent of ribosomes on which the mRNA binds. The rRNA ensures the proper alignment of the mRNA and the ribosomes; the rRNA of the ribosome also has an enzymatic activity (peptidyl transferase) and catalyzes the formation of the peptide bonds between two aligned amino acids. Transfer RNA (tRNA) is one of the smallest of the four types of RNA, usually 70–90 nucleotides long. It carries the correct amino acid to the site of protein synthesis. It is the base pairing between the tRNA and mRNA that allows for the correct amino acid to be inserted in the polypeptide chain. microRNAs are the smallest RNA molecules and their role involves the regulation of gene expression by interfering with the expression of certain mRNA messages. Table 3.2 summarizes features of DNA and RNA. Features of DNA and RNA DNA RNA Function Carries genetic information Involved in protein synthesis Location Remains in the nucleus Leaves the nucleus Structure Double helix Usually single-stranded Sugar Deoxyribose Ribose Pyrimidines Cytosine, thymine Cytosine, uracil Purines Adenine, guanine Adenine, guanine Table 3.2 Even though the RNA is single stranded, most RNA types show extensive intramolecular base pairing between complementary sequences, creating a predictable three-dimensional structure essential for their function. As you have learned, information flow in an organism takes place from DNA to RNA to protein. DNA dictates the structure of mRNA in a process known as transcription , and RNA dictates the structure of protein in a process known as translation . This is known as the Central Dogma of Life, which holds true for all organisms; however, exceptions to the rule occur in connection with viral infections. Link to Learning To learn more about DNA, explore the Howard Hughes Medical Institute BioInteractive animations on the topic of DNA.
u.s._history
Summary 8.1 Competing Visions: Federalists and Democratic-Republicans While they did not yet constitute distinct political parties, Federalists and Anti-Federalists, shortly after the Revolution, found themselves at odds over the Constitution and the power that it concentrated in the federal government. While many of the Anti-Federalists’ fears were assuaged by the adoption of the Bill of Rights in 1791, the early 1790s nevertheless witnessed the rise of two political parties: the Federalists and the Democratic-Republicans. These rival political factions began by defining themselves in relationship to Hamilton’s financial program, a debate that exposed contrasting views of the proper role of the federal government. By championing Hamilton’s bold financial program, Federalists, including President Washington, made clear their intent to use the federal government to stabilize the national economy and overcome the financial problems that had plagued it since the 1780s. Members of the Democratic-Republican opposition, however, deplored the expanded role of the new national government. They argued that the Constitution did not permit the treasury secretary’s expansive program and worried that the new national government had assumed powers it did not rightfully possess. Only on the question of citizenship was there broad agreement: only free, White males who met taxpayer or property qualifications could cast ballots as full citizens of the republic. 8.2 The New American Republic Federalists and Democratic-Republicans interpreted the execution of the French monarch and the violent establishment of a French republic in very different ways. Revolutionaries’ excesses in France and the slave revolt in the French colony of Haiti raised fears among Federalists of similar radicalism and slave uprisings on American shores. They looked to better relationships with Great Britain through Jay’s Treaty. Pinckney’s Treaty, which came about as a result of Jay’s Treaty, improved U.S. relations with the Spanish and opened the Spanish port of New Orleans to American commerce. Democratic-Republicans took a more positive view of the French Revolution and grew suspicious of the Federalists when they brokered Jay’s Treaty. Domestically, the partisan divide came to a dramatic head in western Pennsylvania when distillers of whiskey, many aligned with the Democratic-Republicans, took action against the federal tax on their product. Washington led a massive force to put down the uprising, demonstrating Federalist intolerance of mob action. Though divided on many issues, the majority of White citizens agreed on the necessity of eradicating the Native presence on the frontier. 8.3 Partisan Politics Partisan politics dominated the American political scene at the close of the eighteenth century. The Federalists’ and Democratic-Republicans’ views of the role of government were in direct opposition to each other, and the close elections of 1796 and 1801 show how the nation grappled with these opposing visions. The high tide of the Federalist Party came after the election of 1796, when the United States engaged in the Quasi-War with France. The issues arising from the Quasi-War gave Adams and the Federalists license to expand the powers of the federal government. However, the tide turned with the close election of 1800, when Jefferson began an administration based on Democratic-Republican ideals. A major success of Jefferson’s administration was the Louisiana Purchase of 1803, which helped to fulfill his vision of the United States as an agrarian republic. 8.4 The United States Goes Back to War The United States was drawn into its “Second War of Independence” against Great Britain when the British, engaged in the Napoleonic Wars against France, took liberties with the fledgling nation by impressing (capturing) its sailors on the high seas and arming its Native enemies. The War of 1812 ended with the boundaries of the United States remaining as they were before the war. The Native peoples in the Western Confederacy suffered a significant defeat, losing both their leader Tecumseh and their fight for contested land in the Northwest. The War of 1812 proved to be of great importance because it generated a surge of national pride, with expressions of American identity such as the poem by Francis Scott Key. The United States was unequivocally separate from Britain and could now turn as never before to expansion in the West.
Chapter Outline 8.1 Competing Visions: Federalists and Democratic-Republicans 8.2 The New American Republic 8.3 Partisan Politics 8.4 The United States Goes Back to War Introduction The partisan political cartoon above ( Figure 8.1 ) lampoons Thomas Jefferson’s 1807 Embargo Act, a move that had a devastating effect on American commerce. American farmers and merchants complain to President Jefferson, while the French emperor Napoleon Bonaparte whispers to him, “You shall be King hereafter.” This image illustrates one of many political struggles in the years after the fight for ratification of the Constitution. In the nation’s first few years, no organized political parties existed. This began to change as U.S. citizens argued bitterly about the proper size and scope of the new national government. As a result, the 1790s witnessed the rise of opposing political parties: the Federalists and the Democratic-Republicans. Federalists saw unchecked democracy as a dire threat to the republic, and they pointed to the excesses of the French Revolution as proof of what awaited. Democratic-Republicans opposed the Federalists’ notion that only the wellborn and well educated were able to oversee the republic; they saw it as a pathway to oppression by an aristocracy.
[ { "answer": { "ans_choice": 1, "ans_text": "B" }, "bloom": null, "hl_context": "<hl> Right to a jury trial in civil cases <hl> <hl> Amendment 7 <hl> <hl> Right to a speedy trial by an impartial jury <hl> <hl> Amendment 6 <hl> <hl> Right to keep and bear arms to maintain a well-regulated militia <hl> <hl> Amendment 2 <hl> <hl> Right to freedoms of religion and speech ; right to assemble and to petition the government for redress of grievances <hl> <hl> Amendment 1 <hl> Federalists followed through on their promise to add such a bill in 1789 , when Virginia Representative James Madison introduced and Congress approved the Bill of Rights ( Table 8.1 ) . <hl> Adopted in 1791 , the bill consisted of the first ten amendments to the Constitution and outlined many of the personal rights state constitutions already guaranteed . <hl>", "hl_sentences": "Right to a jury trial in civil cases Amendment 7 Right to a speedy trial by an impartial jury Amendment 6 Right to keep and bear arms to maintain a well-regulated militia Amendment 2 Right to freedoms of religion and speech ; right to assemble and to petition the government for redress of grievances Amendment 1 Adopted in 1791 , the bill consisted of the first ten amendments to the Constitution and outlined many of the personal rights state constitutions already guaranteed .", "question": { "cloze_format": "___ is not a guarantee of the Bill of Rights.", "normal_format": "Which of the following is not one of the rights the Bill of Rights guarantees?", "question_choices": [ "the right to freedom of speech", "the right to an education", "the right to bear arms", "the right to a trial by jury" ], "question_id": "fs-idm149748496", "question_text": "Which of the following is not one of the rights the Bill of Rights guarantees?" }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 1, "ans_text": "the public credit plan" }, "bloom": null, "hl_context": "Hamilton ’ s program ignited a heated debate in Congress . A great many of both Confederation and state notes had found their way into the hands of speculators , who had bought them from hard-pressed veterans in the 1780s and paid a fraction of their face value in anticipation of redeeming them at full value at a later date . <hl> Because these speculators held so many notes , many in Congress objected that Hamilton ’ s plan would benefit them at the expense of the original note-holders . <hl> <hl> One of those who opposed Hamilton ’ s 1790 report was James Madison , who questioned the fairness of a plan that seemed to cheat poor soldiers . <hl> <hl> Hamilton designed his “ Report on Public Credit ” ( later called “ First Report on Public Credit ” ) to ensure the survival of the new and shaky American republic . <hl> He knew the importance of making the United States financially reliable , secure , and strong , and his plan provided a blueprint to achieve that goal . He argued that his plan would satisfy creditors , citing the goal of “ doing justice to the creditors of the nation . ” At the same time , the plan would work “ to promote the increasing respectability of the American name ; to answer the calls for justice ; to restore landed property to its due value ; to furnish new resources both to agriculture and commerce ; to cement more closely the union of the states ; to add to their security against foreign attack ; to establish public order on the basis of upright and liberal policy . ”", "hl_sentences": "Because these speculators held so many notes , many in Congress objected that Hamilton ’ s plan would benefit them at the expense of the original note-holders . One of those who opposed Hamilton ’ s 1790 report was James Madison , who questioned the fairness of a plan that seemed to cheat poor soldiers . Hamilton designed his “ Report on Public Credit ” ( later called “ First Report on Public Credit ” ) to ensure the survival of the new and shaky American republic .", "question": { "cloze_format": "Alecander Hamilton's ___ seemed to benefit speculators at the expense of poor soldiers.", "normal_format": "Which of Alexander Hamilton’s financial policies and programs seemed to benefit speculators at the expense of poor soldiers?", "question_choices": [ "the creation of a national bank", "the public credit plan", "the tax on whiskey", "the “Report on Manufactures”" ], "question_id": "fs-idm149271632", "question_text": "Which of Alexander Hamilton’s financial policies and programs seemed to benefit speculators at the expense of poor soldiers?" }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 0, "ans_text": "It gave the United States land rights in the West Indies." }, "bloom": null, "hl_context": "<hl> Jay ’ s Treaty confirmed the fears of Democratic-Republicans , who saw it as a betrayal of republican France , cementing the idea that the Federalists favored aristocracy and monarchy . <hl> Partisan American newspapers tried to sway public opinion , while the skillful writing of Hamilton , who published a number of essays on the subject , explained the benefits of commerce with Great Britain . The resulting 1794 agreement , known as Jay ’ s Treaty , fulfilled most of his original goals . <hl> The British would turn over the frontier posts in the Northwest , American ships would be allowed to trade freely in the West Indies , and the United States agreed to assemble a commission charged with settling colonial debts U . S . citizens owed British merchants . <hl> <hl> The treaty did not address the important issue of impressment , however — the British navy ’ s practice of forcing or “ impressing ” American sailors to work and fight on British warships . <hl> Jay ’ s Treaty led the Spanish , who worried that it signaled an alliance between the United States and Great Britain , to negotiate a treaty of their own — Pinckney ’ s Treaty — that allowed American commerce to flow through the Spanish port of New Orleans . Pinckney ’ s Treaty allowed American farmers , who were moving in greater numbers to the Ohio River Valley , to ship their products down the Ohio and Mississippi Rivers to New Orleans , where they could be transported to East Coast markets . In 1793 , the revolutionary French government sent Edmond-Charles Genêt to the United States to negotiate an alliance with the U . S . government . France authorized Genêt to issue letters of marque — documents authorizing ships and their crews to engage in piracy — to allow him to arm captured British ships in American ports with U . S . soldiers . Genêt arrived in Charleston , South Carolina , amid great Democratic-Republican fanfare . He immediately began commissioning American privateer ships and organizing volunteer American militias to attack Spanish holdings in the Americas , then traveled to Philadelphia , gathering support for the French cause along the way . President Washington and Hamilton denounced Genêt , knowing his actions threatened to pull the United States into a war with Great Britain . The Citizen Genêt affair , as it became known , spurred Great Britain to instruct its naval commanders in the West Indies to seize all ships trading with the French . The British captured hundreds of American ships and their cargoes , increasing the possibility of war between the two countries . In this tense situation , Great Britain worked to prevent a wider conflict by ending its seizure of American ships and offered to pay for captured cargoes . Hamilton saw an opportunity and recommended to Washington that the United States negotiate . <hl> Supreme Court Justice John Jay was sent to Britain , instructed by Hamilton to secure compensation for captured American ships ; ensure the British leave the Northwest outposts they still occupied despite the 1783 Treaty of Paris ; and gain an agreement for American trade in the West Indies . <hl> Even though Jay personally disliked slavery , his mission also required him to seek compensation from the British for self-emancipated enslaved people who left with the British at the end of the Revolutionary War .", "hl_sentences": "Jay ’ s Treaty confirmed the fears of Democratic-Republicans , who saw it as a betrayal of republican France , cementing the idea that the Federalists favored aristocracy and monarchy . The British would turn over the frontier posts in the Northwest , American ships would be allowed to trade freely in the West Indies , and the United States agreed to assemble a commission charged with settling colonial debts U . S . citizens owed British merchants . The treaty did not address the important issue of impressment , however — the British navy ’ s practice of forcing or “ impressing ” American sailors to work and fight on British warships . Supreme Court Justice John Jay was sent to Britain , instructed by Hamilton to secure compensation for captured American ships ; ensure the British leave the Northwest outposts they still occupied despite the 1783 Treaty of Paris ; and gain an agreement for American trade in the West Indies .", "question": { "cloze_format": "___ is not true of Jay's Treaty of 1794.", "normal_format": "Which of the following was not true of Jay’s Treaty of 1794?", "question_choices": [ "It gave the United States land rights in the West Indies.", "It gave American ships the right to trade in the West Indies.", "It hardened differences between the political parties of the United States.", "It stipulated that U.S. citizens would repay their debts from the Revolutionary War." ], "question_id": "fs-idm91813520", "question_text": "Which of the following was not true of Jay’s Treaty of 1794?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 3, "ans_text": "D" }, "bloom": null, "hl_context": "With their emphasis on personal freedoms , the whiskey rebels aligned themselves with the Democratic-Republican Party . <hl> They saw the tax as part of a larger Federalist plot to destroy their republican liberty and , in its most extreme interpretation , turn the United States into a monarchy . <hl> The federal government lowered the tax , but when federal officials tried to subpoena those distillers who remained intractable , trouble escalated . Washington responded by creating a thirteen-thousand-man militia , drawn from several states , to put down the rebellion ( Figure 8.7 ) . This force made it known , both domestically and to the European powers that looked on in anticipation of the new republic ’ s collapse , that the national government would do everything in its power to ensure the survival of the United States . While the wars in France and the Caribbean divided American citizens , a major domestic test of the new national government came in 1794 over the issue of a tax on whiskey , an important part of Hamilton ’ s financial program . <hl> In 1791 , Congress had authorized a tax of 7.5 cents per gallon of whiskey and rum . <hl> <hl> Although most citizens paid without incident , trouble erupted in four western Pennsylvania counties in an uprising known as the Whiskey Rebellion . <hl>", "hl_sentences": "They saw the tax as part of a larger Federalist plot to destroy their republican liberty and , in its most extreme interpretation , turn the United States into a monarchy . In 1791 , Congress had authorized a tax of 7.5 cents per gallon of whiskey and rum . Although most citizens paid without incident , trouble erupted in four western Pennsylvania counties in an uprising known as the Whiskey Rebellion .", "question": { "cloze_format": "___ was the primary complaint of the rebels in the Whiskey Rebellion.", "normal_format": "What was the primary complaint of the rebels in the Whiskey Rebellion?", "question_choices": [ "the ban on alcohol", "the lack of political representation for farmers", "the need to fight Native Americans for more land", "the tax on whiskey and rum" ], "question_id": "fs-idm43472448", "question_text": "What was the primary complaint of the rebels in the Whiskey Rebellion?" }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 3, "ans_text": "D" }, "bloom": null, "hl_context": "The war between Great Britain and France in the 1790s shaped U . S . foreign policy . As a new and , in comparison to the European powers , extremely weak nation , the American republic had no control over European events , and no real leverage to obtain its goals of trading freely in the Atlantic . <hl> To Federalist president John Adams , relations with France posed the biggest problem . <hl> After the Terror , the French Directory ruled France from 1795 to 1799 . During this time , Napoleon rose to power .", "hl_sentences": "To Federalist president John Adams , relations with France posed the biggest problem .", "question": { "cloze_format": "The primary issue of Adams's presidency was ___.", "normal_format": "What was the primary issue of Adams’s presidency?", "question_choices": [ "war with Spain", "relations with the native population", "infighting within the Federalist Party", "relations with France" ], "question_id": "fs-idp2375984", "question_text": "What was the primary issue of Adams’s presidency?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 1, "ans_text": "the XYZ affair" }, "bloom": null, "hl_context": "<hl> The animosity between the political parties exploded into open violence in 1804 , when Aaron Burr , Jefferson ’ s first vice president , and Alexander Hamilton engaged in a duel . <hl> <hl> When Democratic-Republican Burr lost his bid for the office of governor of New York , he was quick to blame Hamilton , who had long hated him and had done everything in his power to discredit him . <hl> <hl> On July 11 , the two antagonists met in Weehawken , New Jersey , to exchange bullets in a duel in which Burr shot and mortally wounded Hamilton . <hl> <hl> One of Adams ’ s appointees , William Marbury , had been selected to be a justice of the peace in the District of Columbia , and when his commission did not arrive , he petitioned the Supreme Court for an explanation from Jefferson ’ s secretary of state , James Madison . <hl> <hl> In deciding the case , Marbury v . Madison , in 1803 , Chief Justice John Marshall agreed that Marbury had the right to a legal remedy , establishing that individuals had rights even the president of the United States could not abridge . <hl> <hl> However , Marshall also found that Congress ’ s Judicial Act of 1789 , which would have given the Supreme Court the power to grant Marbury remedy , was unconstitutional because the Constitution did not allow for cases like Marbury ’ s to come directly before the Supreme Court . <hl> <hl> Thus , Marshall established the principle of judicial review , which strengthened the court by asserting its power to review ( and possibly nullify ) the actions of Congress and the president . <hl> Jefferson was not pleased , but neither did Marbury get his commission . <hl> The surge of animosity against France during the Quasi-War led Congress to pass several measures that in time undermined Federalist power . <hl> <hl> These 1798 war measures , known as the Alien and Sedition Acts , aimed to increase national security against what most had come to regard as the French menace . <hl> The Alien Act and the Alien Enemies Act took particular aim at French immigrants fleeing the West Indies by giving the president the power to deport new arrivals who appeared to be a threat to national security . The act expired in 1800 with no immigrants having been deported . <hl> The Sedition Act imposed harsh penalties — up to five years ’ imprisonment and a massive fine of $ 5,000 in 1790 dollars — on those convicted of speaking or writing “ in a scandalous or malicious ” manner against the government of the United States . <hl> <hl> Twenty-five men , all Democratic-Republicans , were indicted under the act , and ten were convicted . <hl> <hl> One of these was Congressman Matthew Lyon ( Figure 8.12 ) , representative from Vermont , who had launched his own newspaper , The Scourge Of Aristocracy and Repository of Important Political Truth . <hl> In 1797 , Adams sought a diplomatic solution to the conflict with France and dispatched envoys to negotiate terms . The French foreign minister , Charles-Maurice de Talleyrand , sent emissaries who told the American envoys that the United States must repay all outstanding debts owed to France , lend France 32 million guilders ( Dutch currency ) , and pay a £ 50,000 bribe before any negotiations could take place . <hl> News of the attempt to extract a bribe , known as the XYZ affair because the French emissaries were referred to as X , Y , and Z in letters that President Adams released to Congress , outraged the American public and turned public opinion decidedly against France ( Figure 8.11 ) . <hl> In the court of public opinion , Federalists appeared to have been correct in their interpretation of France , while the pro-French Democratic-Republicans had been misled .", "hl_sentences": "The animosity between the political parties exploded into open violence in 1804 , when Aaron Burr , Jefferson ’ s first vice president , and Alexander Hamilton engaged in a duel . When Democratic-Republican Burr lost his bid for the office of governor of New York , he was quick to blame Hamilton , who had long hated him and had done everything in his power to discredit him . On July 11 , the two antagonists met in Weehawken , New Jersey , to exchange bullets in a duel in which Burr shot and mortally wounded Hamilton . One of Adams ’ s appointees , William Marbury , had been selected to be a justice of the peace in the District of Columbia , and when his commission did not arrive , he petitioned the Supreme Court for an explanation from Jefferson ’ s secretary of state , James Madison . In deciding the case , Marbury v . Madison , in 1803 , Chief Justice John Marshall agreed that Marbury had the right to a legal remedy , establishing that individuals had rights even the president of the United States could not abridge . However , Marshall also found that Congress ’ s Judicial Act of 1789 , which would have given the Supreme Court the power to grant Marbury remedy , was unconstitutional because the Constitution did not allow for cases like Marbury ’ s to come directly before the Supreme Court . Thus , Marshall established the principle of judicial review , which strengthened the court by asserting its power to review ( and possibly nullify ) the actions of Congress and the president . The surge of animosity against France during the Quasi-War led Congress to pass several measures that in time undermined Federalist power . These 1798 war measures , known as the Alien and Sedition Acts , aimed to increase national security against what most had come to regard as the French menace . The Sedition Act imposed harsh penalties — up to five years ’ imprisonment and a massive fine of $ 5,000 in 1790 dollars — on those convicted of speaking or writing “ in a scandalous or malicious ” manner against the government of the United States . Twenty-five men , all Democratic-Republicans , were indicted under the act , and ten were convicted . One of these was Congressman Matthew Lyon ( Figure 8.12 ) , representative from Vermont , who had launched his own newspaper , The Scourge Of Aristocracy and Repository of Important Political Truth . News of the attempt to extract a bribe , known as the XYZ affair because the French emissaries were referred to as X , Y , and Z in letters that President Adams released to Congress , outraged the American public and turned public opinion decidedly against France ( Figure 8.11 ) .", "question": { "cloze_format": "___ is not an example of partisan acrimony.", "normal_format": "Which of the following events is not an example of partisan acrimony?", "question_choices": [ "the jailing of Matthew Lyon", "the XYZ affair", "the Marbury v. Madison case", "the Hamilton-Burr duel" ], "question_id": "fs-idm48332208", "question_text": "Which of the following events is not an example of partisan acrimony?" }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 0, "ans_text": "A" }, "bloom": null, "hl_context": "<hl> The purchase of Louisiana came about largely because of circumstances beyond Jefferson ’ s control , though he certainly recognized the implications of the transaction . <hl> Until 1801 , Spain had controlled New Orleans and had given the United States the right to traffic goods in the port without paying customs duties . That year , however , the Spanish had ceded Louisiana ( and New Orleans ) to France . In 1802 , the United States lost its right to deposit goods free in the port , causing outrage among many , some of whom called for war with France . <hl> Jefferson , who wanted to expand the United States to bring about his “ empire of liberty , ” realized his greatest triumph in 1803 when the United States bought the Louisiana territory from France . <hl> For $ 15 million — a bargain price , considering the amount of land involved — the United States doubled in size . Perhaps the greatest real estate deal in American history , the Louisiana Purchase greatly enhanced the Jeffersonian vision of the United States as an agrarian republic in which yeomen farmers worked the land . <hl> Jefferson also wanted to bolster trade in the West , seeing the port of New Orleans and the Mississippi River ( then the western boundary of the United States ) as crucial to American agricultural commerce . <hl> <hl> In his mind , farmers would send their produce down the Mississippi River to New Orleans , where it would be sold to European traders . <hl>", "hl_sentences": "The purchase of Louisiana came about largely because of circumstances beyond Jefferson ’ s control , though he certainly recognized the implications of the transaction . Jefferson , who wanted to expand the United States to bring about his “ empire of liberty , ” realized his greatest triumph in 1803 when the United States bought the Louisiana territory from France . Jefferson also wanted to bolster trade in the West , seeing the port of New Orleans and the Mississippi River ( then the western boundary of the United States ) as crucial to American agricultural commerce . In his mind , farmers would send their produce down the Mississippi River to New Orleans , where it would be sold to European traders .", "question": { "cloze_format": "The importance of the Louisiana Purchase was ___.", "normal_format": "What was the importance of the Louisiana Purchase?", "question_choices": [ "It gave the United States control of the port of New Orleans for trade.", "It opened up the possibility of quick trade routes to Asia.", "It gave the United States political leverage against the Spanish.", "It provided Napoleon with an impetus to restore France’s empire." ], "question_id": "fs-idm9559776", "question_text": "What was the importance of the Louisiana Purchase?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 2, "ans_text": "The British navy captured American ships on the high seas and impressed their sailors into service for the British." }, "bloom": null, "hl_context": "<hl> France and England , engaged in the Napoleonic Wars , which raged between 1803 and 1815 , both declared open season on American ships , which they seized on the high seas . <hl> <hl> England was the major offender , since the Royal Navy , following a time-honored practice , “ impressed ” American sailors by forcing them into its service . <hl> The issue came to a head in 1807 when the HMS Leopard , a British warship , fired on a U . S . naval ship , the Chesapeake , off the coast of Norfolk , Virginia . The British then boarded the ship and took four sailors . Jefferson chose what he thought was the best of his limited options and responded to the crisis through the economic means of a sweeping ban on trade , the Embargo Act of 1807 . This law prohibited American ships from leaving their ports until Britain and France stopped seizing them on the high seas . As a result of the embargo , American commerce came to a near-total halt . <hl> THE EMBARGO OF 1807 <hl>", "hl_sentences": "France and England , engaged in the Napoleonic Wars , which raged between 1803 and 1815 , both declared open season on American ships , which they seized on the high seas . England was the major offender , since the Royal Navy , following a time-honored practice , “ impressed ” American sailors by forcing them into its service . THE EMBARGO OF 1807", "question": { "cloze_format": "The Embargo of 1807 was prompted by ___.", "normal_format": "What prompted the Embargo of 1807?", "question_choices": [ "British soldiers burned the U.S. capitol.", "The British supplied arms to Native fighters.", "The British navy captured American ships on the high seas and impressed their sailors into service for the British.", "The British hadn’t abandoned their posts in the Northwest Territory as required by Jay’s Treaty." ], "question_id": "fs-idp3289616", "question_text": "What prompted the Embargo of 1807?" }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 1, "ans_text": "B" }, "bloom": null, "hl_context": "<hl> Americana Francis Scott Key ’ s “ In Defense of Fort McHenry ” After the British bombed Baltimore ’ s Fort McHenry in 1814 but failed to overcome the U . S . forces there , Francis Scott Key was inspired by the sight of the American flag , which remained hanging proudly in the aftermath . <hl> <hl> He wrote the poem “ In Defense of Fort McHenry , ” which was later set to the tune of a British song called “ The Anacreontic Song ” and eventually became the U . S . national anthem , “ The Star-Spangled Banner . ” <hl> These victories could not turn the tide of the war , however . With the British gaining the upper hand during the Napoleonic Wars and Napoleon ’ s French army on the run , Great Britain now could divert skilled combat troops from Europe to fight in the United States . In July 1814 , forty-five hundred hardened British soldiers sailed up the Chesapeake Bay and burned Washington , DC , to the ground , forcing President Madison and his wife to run for their lives ( Figure 8.17 ) . According to one report , they left behind a dinner the British officers ate . <hl> That summer , the British shelled Baltimore , hoping for another victory . <hl> <hl> However , they failed to dislodge the U . S . forces , whose survival of the bombardment inspired Francis Scott Key to write “ The Star-Spangled Banner . ” <hl>", "hl_sentences": "Americana Francis Scott Key ’ s “ In Defense of Fort McHenry ” After the British bombed Baltimore ’ s Fort McHenry in 1814 but failed to overcome the U . S . forces there , Francis Scott Key was inspired by the sight of the American flag , which remained hanging proudly in the aftermath . He wrote the poem “ In Defense of Fort McHenry , ” which was later set to the tune of a British song called “ The Anacreontic Song ” and eventually became the U . S . national anthem , “ The Star-Spangled Banner . ” That summer , the British shelled Baltimore , hoping for another victory . However , they failed to dislodge the U . S . forces , whose survival of the bombardment inspired Francis Scott Key to write “ The Star-Spangled Banner . ”", "question": { "cloze_format": "The event that inspired “The Star-Spangled Banner” was ___ .", "normal_format": "What event inspired “The Star-Spangled Banner”?", "question_choices": [ "Betsy Ross sewing the first American flag raised during a time of war", "the British bombardment of Baltimore", "the British burning of Washington, DC", "the naval battle between the Leopard and the Chesapeake" ], "question_id": "fs-idp188236864", "question_text": "What event inspired “The Star-Spangled Banner”?" }, "references_are_paraphrase": 0 } ]
8
8.1 Competing Visions: Federalists and Democratic-Republicans Learning Objectives By the end of this section, you will be able to: Describe the competing visions of the Federalists and the Democratic-Republicans Identify the protections granted to citizens under the Bill of Rights Explain Alexander Hamilton’s financial programs as secretary of the treasury In June 1788, New Hampshire became the ninth state to ratify the federal Constitution, and the new plan for a strong central government went into effect. Elections for the first U.S. Congress were held in 1788 and 1789, and members took their seats in March 1789. In a reflection of the trust placed in him as the personification of republican virtue, George Washington became the first president in April 1789. John Adams served as his vice president; the pairing of a representative from Virginia (Washington) with one from Massachusetts (Adams) symbolized national unity. Nonetheless, political divisions quickly became apparent. Washington and Adams represented the Federalist Party, which generated a backlash among those who resisted the new government’s assertions of federal power. FEDERALISTS IN POWER Though the Revolution had overthrown British rule in the United States, supporters of the 1787 federal constitution, known as Federalists, adhered to a decidedly British notion of social hierarchy. The Federalists did not, at first, compose a political party. Instead, Federalists held certain shared assumptions. For them, political participation continued to be linked to property rights, which barred many citizens from voting or holding office. Federalists did not believe the Revolution had changed the traditional social roles between women and men, or between Whites and other races. They did believe in clear distinctions in rank and intelligence. To these supporters of the Constitution, the idea that all were equal appeared ludicrous. Women, Black, and Native peoples, they argued, had to know their place as secondary to White male citizens. Attempts to impose equality, they feared, would destroy the republic. The United States was not created to be a democracy. The architects of the Constitution committed themselves to leading the new republic, and they held a majority among the members of the new national government. Indeed, as expected, many assumed the new executive posts the first Congress created. Washington appointed Alexander Hamilton, a leading Federalist, as secretary of the treasury. For secretary of state, he chose Thomas Jefferson. For secretary of war, he appointed Henry Knox, who had served with him during the Revolutionary War. Edmond Randolph, a Virginia delegate to the Constitutional Convention, was named attorney general. In July 1789, Congress also passed the Judiciary Act, creating a Supreme Court of six justices headed by those who were committed to the new national government. Congress passed its first major piece of legislation by placing a duty on imports under the 1789 Tariff Act. Intended to raise revenue to address the country’s economic problems, the act was a victory for nationalists, who favored a robust, powerful federal government and had worked unsuccessfully for similar measures during the Confederation Congress in the 1780s. Congress also placed a fifty-cent-per-ton duty (based on materials transported, not the weight of a ship) on foreign ships coming into American ports, a move designed to give the commercial advantage to American ships and goods. THE BILL OF RIGHTS Many Americans opposed the 1787 Constitution because it seemed a dangerous concentration of centralized power that threatened the rights and liberties of ordinary U.S. citizens. These opponents, known collectively as Anti-Federalists, did not constitute a political party, but they united in demanding protection for individual rights, and several states made the passing of a bill of rights a condition of their acceptance of the Constitution. Rhode Island and North Carolina rejected the Constitution because it did not already have this specific bill of rights. Federalists followed through on their promise to add such a bill in 1789, when Virginia Representative James Madison introduced and Congress approved the Bill of Rights ( Table 8.1 ). Adopted in 1791, the bill consisted of the first ten amendments to the Constitution and outlined many of the personal rights state constitutions already guaranteed. Amendment 1 Right to freedoms of religion and speech; right to assemble and to petition the government for redress of grievances Amendment 2 Right to keep and bear arms to maintain a well-regulated militia Amendment 3 Right not to house soldiers during time of war Amendment 4 Right to be secure from unreasonable search and seizure Amendment 5 Rights in criminal cases, including to due process and indictment by grand jury for capital crimes, as well as the right not to testify against oneself Amendment 6 Right to a speedy trial by an impartial jury Amendment 7 Right to a jury trial in civil cases Amendment 8 Right not to face excessive bail or fines, or cruel and unusual punishment Amendment 9 Rights retained by the people, even if they are not specifically enumerated by the Constitution Amendment 10 States’ rights to powers not specifically delegated to the federal government Table 8.1 Rights Protected by the First Ten Amendments The adoption of the Bill of Rights softened the Anti-Federalists’ opposition to the Constitution and gave the new federal government greater legitimacy among those who otherwise distrusted the new centralized power created by men of property during the secret 1787 Philadelphia Constitutional Convention. ALEXANDER HAMILTON’S PROGRAM Alexander Hamilton, Washington’s secretary of the treasury, was an ardent nationalist who believed a strong federal government could solve many of the new country’s financial ills. Born in the West Indies, Hamilton had worked on a St. Croix plantation as a teenager and was in charge of the accounts at a young age. He knew the Atlantic trade very well and used that knowledge in setting policy for the United States. In the early 1790s, he created the foundation for the U.S. financial system. He understood that a robust federal government would provide a solid financial foundation for the country. The United States began mired in debt. In 1789, when Hamilton took up his post, the federal debt was over $53 million. The states had a combined debt of around $25 million, and the United States had been unable to pay its debts in the 1780s and was therefore considered a credit risk by European countries. Hamilton wrote three reports offering solutions to the economic crisis brought on by these problems. The first addressed public credit, the second addressed banking, and the third addressed raising revenue. The Report on Public Credit For the national government to be effective, Hamilton deemed it essential to have the support of those to whom it owed money: the wealthy, domestic creditor class as well as foreign creditors. In January 1790, he delivered his “ Report on Public Credit “ ( Figure 8.3 ), addressing the pressing need of the new republic to become creditworthy. He recommended that the new federal government honor all its debts, including all paper money issued by the Confederation and the states during the war, at face value. Hamilton especially wanted wealthy American creditors who held large amounts of paper money to be invested, literally, in the future and welfare of the new national government. He also understood the importance of making the new United States financially stable for creditors abroad. To pay these debts, Hamilton proposed that the federal government sell bonds—federal interest-bearing notes—to the public. These bonds would have the backing of the government and yield interest payments. Creditors could exchange their old notes for the new government bonds. Hamilton wanted to give the paper money that states had issued during the war the same status as government bonds; these federal notes would begin to yield interest payments in 1792. Hamilton designed his “Report on Public Credit” (later called “First Report on Public Credit”) to ensure the survival of the new and shaky American republic. He knew the importance of making the United States financially reliable, secure, and strong, and his plan provided a blueprint to achieve that goal. He argued that his plan would satisfy creditors, citing the goal of “doing justice to the creditors of the nation.” At the same time, the plan would work “to promote the increasing respectability of the American name; to answer the calls for justice; to restore landed property to its due value; to furnish new resources both to agriculture and commerce; to cement more closely the union of the states; to add to their security against foreign attack; to establish public order on the basis of upright and liberal policy.” Hamilton’s program ignited a heated debate in Congress. A great many of both Confederation and state notes had found their way into the hands of speculators, who had bought them from hard-pressed veterans in the 1780s and paid a fraction of their face value in anticipation of redeeming them at full value at a later date. Because these speculators held so many notes, many in Congress objected that Hamilton’s plan would benefit them at the expense of the original note-holders. One of those who opposed Hamilton’s 1790 report was James Madison, who questioned the fairness of a plan that seemed to cheat poor soldiers. Not surprisingly, states with a large debt, like South Carolina, supported Hamilton’s plan, while states with less debt, like North Carolina, did not. To gain acceptance of his plan, Hamilton worked out a compromise with Virginians Madison and Jefferson, whereby in return for their support he would give up New York City as the nation’s capital and agree on a more southern location, which they preferred. In July 1790, a site along the Potomac River was selected as the new “federal city,” which became the District of Columbia. Hamilton’s plan to convert notes to bonds worked extremely well to restore European confidence in the U.S. economy. It also proved a windfall for creditors, especially those who had bought up state and Confederation notes at far less than face value. But it immediately generated controversy about the size and scope of the government. Some saw the plan as an unjust use of federal power, while Hamilton argued that Article 1, Section 8 of the Constitution granted the government “implied powers” that gave the green light to his program. The Report on a National Bank As secretary of the treasury, Hamilton hoped to stabilize the American economy further by establishing a national bank. The United States operated with a flurry of different notes from multiple state banks and no coherent regulation. By proposing that the new national bank buy up large volumes of state bank notes and demanding their conversion into gold, Hamilton especially wanted to discipline those state banks that issued paper money irresponsibly. To that end, he delivered his “Report on a National Bank” in December 1790, proposing a Bank of the United States, an institution modeled on the Bank of England. The bank would issue loans to American merchants and bills of credit (federal bank notes that would circulate as money) while serving as a repository of government revenue from the sale of land. Stockholders would own the bank, along with the federal government. Like the recommendations in his “Report on Public Credit,” Hamilton’s bank proposal generated opposition. Jefferson, in particular, argued that the Constitution did not permit the creation of a national bank. In response, Hamilton again invoked the Constitution’s implied powers. President Washington backed Hamilton’s position and signed legislation creating the bank in 1791. The Report on Manufactures The third report Hamilton delivered to Congress, known as the “Report on Manufactures,” addressed the need to raise revenue to pay the interest on the national debt. Using the power to tax as provided under the Constitution, Hamilton put forth a proposal to tax American-made whiskey. He also knew the importance of promoting domestic manufacturing so the new United States would no longer have to rely on imported manufactured goods. To break from the old colonial system, Hamilton therefore advocated tariffs on all foreign imports to stimulate the production of American-made goods. To promote domestic industry further, he proposed federal subsidies to American industries. Like all of Hamilton’s programs, the idea of government involvement in the development of American industries was new. With the support of Washington, the entire Hamiltonian economic program received the necessary support in Congress to be implemented. In the long run, Hamilton’s financial program helped to rescue the United States from its state of near-bankruptcy in the late 1780s. His initiatives marked the beginning of an American capitalism, making the republic creditworthy, promoting commerce, and setting for the nation a solid financial foundation. His policies also facilitated the growth of the stock market, as U.S. citizens bought and sold the federal government’s interest-bearing certificates. THE DEMOCRATIC-REPUBLICAN PARTY AND THE FIRST PARTY SYSTEM James Madison and Thomas Jefferson felt the federal government had overstepped its authority by adopting the treasury secretary’s plan. Madison found Hamilton’s scheme immoral and offensive. He argued that it turned the reins of government over to the class of speculators who profited at the expense of hardworking citizens. Jefferson, who had returned to the United States in 1790 after serving as a diplomat in France, tried unsuccessfully to convince Washington to block the creation of a national bank. He also took issue with what he perceived as favoritism given to commercial classes in the principal American cities. He thought urban life widened the gap between the wealthy few and an underclass of landless poor workers who, because of their oppressed condition, could never be good republican property owners. Rural areas, in contrast, offered far more opportunities for property ownership and virtue. In 1783 Jefferson wrote, “Those who labor in the earth are the chosen people of God, if ever he had a chosen people.” Jefferson believed that self-sufficient, property-owning republican citizens or yeoman farmers held the key to the success and longevity of the American republic. (As a creature of his times, he did not envision a similar role for either women or nonWhite men.) To him, Hamilton’s program seemed to encourage economic inequalities and work against the ordinary American yeoman. Opposition to Hamilton, who had significant power in the new federal government, including the ear of President Washington, began in earnest in the early 1790s. Jefferson turned to his friend Philip Freneau to help organize the effort through the publication of the National Gazette as a counter to the Federalist press, especially the Gazette of the United States ( Figure 8.4 ). From 1791 until 1793, when it ceased publication, Freneau’s partisan paper attacked Hamilton’s program and Washington’s administration. “Rules for Changing a Republic into a Monarchy,” written by Freneau, is an example of the type of attack aimed at the national government, and especially at the elitism of the Federalist Party. Newspapers in the 1790s became enormously important in American culture as partisans like Freneau attempted to sway public opinion. These newspapers did not aim to be objective; instead, they served to broadcast the views of a particular party. Opposition to the Federalists led to the formation of Democratic-Republican societies, composed of men who felt the domestic policies of the Washington administration were designed to enrich the few while ignoring everyone else. Democratic-Republicans championed limited government. Their fear of centralized power originated in the experience of the 1760s and 1770s when the distant, overbearing, and seemingly corrupt British Parliament attempted to impose its will on the colonies. The 1787 federal constitution, written in secret by fifty-five wealthy men of property and standing, ignited fears of a similar menacing plot. To opponents, the Federalists promoted aristocracy and a monarchical government—a betrayal of what many believed to be the goal of the American Revolution. While wealthy merchants and planters formed the core of the Federalist leadership, members of the Democratic-Republican societies in cities like Philadelphia and New York came from the ranks of artisans. These citizens saw themselves as acting in the spirit of 1776, this time not against the haughty British but by what they believed to have replaced them—a commercial class with no interest in the public good. Their political efforts against the Federalists were a battle to preserve republicanism, to promote the public good against private self-interest. They published their views, held meetings to voice their opposition, and sponsored festivals and parades. In their strident newspapers attacks, they also worked to undermine the traditional forms of deference and subordination to aristocrats, in this case the Federalist elites. Some members of northern Democratic-Republican clubs denounced slavery as well. DEFINING CITIZENSHIP While questions regarding the proper size and scope of the new national government created a divide among Americans and gave rise to political parties, a consensus existed among men on the issue of who qualified and who did not qualify as a citizen. The 1790 Naturalization Act defined citizenship in stark racial terms. To be a citizen of the American republic, an immigrant had to be a “free White person” of “good character.” By excluding enslaved, free Black, Native, and Asian people from citizenship, the act laid the foundation for the United States as a republic of White men. Full citizenship that included the right to vote was restricted as well. Many state constitutions directed that only male property owners or taxpayers could vote. For women, the right to vote remained out of reach except in the state of New Jersey. In 1776, the fervor of the Revolution led New Jersey revolutionaries to write a constitution extending the right to vote to unmarried women who owned property worth £50. Federalists and Democratic-Republicans competed for the votes of New Jersey women who met the requirements to cast ballots. This radical innovation continued until 1807, when New Jersey restricted voting to free White males. 8.2 The New American Republic Learning Objectives By the end of this section, you will be able to: Identify the major foreign and domestic uprisings of the early 1790s Explain the effect of these uprisings on the political system of the United States The colonies’ alliance with France, secured after the victory at Saratoga in 1777, proved crucial in their victory against the British, and during the 1780s France and the new United States enjoyed a special relationship. Together they had defeated their common enemy, Great Britain. But despite this shared experience, American opinions regarding France diverged sharply in the 1790s when France underwent its own revolution. Democratic-Republicans seized on the French revolutionaries’ struggle against monarchy as the welcome harbinger of a larger republican movement around the world. To the Federalists, however, the French Revolution represented pure anarchy, especially after the execution of the French king in 1793. Along with other foreign and domestic uprisings, the French Revolution helped harden the political divide in the United States in the early 1790s. THE FRENCH REVOLUTION The French Revolution, which began in 1789, further split American thinkers into different ideological camps, deepening the political divide between Federalists and their Democratic-Republican foes. At first, in 1789 and 1790, the revolution in France appeared to most in the United States as part of a new chapter in the rejection of corrupt monarchy, a trend inspired by the American Revolution. A constitutional monarchy replaced the absolute monarchy of Louis XVI in 1791, and in 1792, France was declared a republic. Republican liberty, the creed of the United States, seemed to be ushering in a new era in France. Indeed, the American Revolution served as an inspiration for French revolutionaries. The events of 1793 and 1794 challenged the simple interpretation of the French Revolution as a happy chapter in the unfolding triumph of republican government over monarchy. The French king was executed in January 1793 ( Figure 8.5 ), and the next two years became known as the Terror , a period of extreme violence against perceived enemies of the revolutionary government. Revolutionaries advocated direct representative democracy, dismantled Catholicism, replaced that religion with a new philosophy known as the Cult of the Supreme Being, renamed the months of the year, and relentlessly employed the guillotine against their enemies. Federalists viewed these excesses with growing alarm, fearing that the radicalism of the French Revolution might infect the minds of citizens at home. Democratic-Republicans interpreted the same events with greater optimism, seeing them as a necessary evil of eliminating the monarchy and aristocratic culture that supported the privileges of a hereditary class of rulers. The controversy in the United States intensified when France declared war on Great Britain and Holland in February 1793. France requested that the United States make a large repayment of the money it had borrowed from France to fund the Revolutionary War. However, Great Britain would judge any aid given to France as a hostile act. Washington declared the United States neutral in 1793, but Democratic-Republican groups denounced neutrality and declared their support of the French republicans. The Federalists used the violence of the French revolutionaries as a reason to attack Democratic-Republicanism in the United States, arguing that Jefferson and Madison would lead the country down a similarly disastrous path. THE CITIZEN GENÊT AFFAIR AND JAY’S TREATY In 1793, the revolutionary French government sent Edmond-Charles Genêt to the United States to negotiate an alliance with the U.S. government. France authorized Genêt to issue letters of marque —documents authorizing ships and their crews to engage in piracy—to allow him to arm captured British ships in American ports with U.S. soldiers. Genêt arrived in Charleston, South Carolina, amid great Democratic-Republican fanfare. He immediately began commissioning American privateer ships and organizing volunteer American militias to attack Spanish holdings in the Americas, then traveled to Philadelphia, gathering support for the French cause along the way. President Washington and Hamilton denounced Genêt, knowing his actions threatened to pull the United States into a war with Great Britain. The Citizen Genêt affair , as it became known, spurred Great Britain to instruct its naval commanders in the West Indies to seize all ships trading with the French. The British captured hundreds of American ships and their cargoes, increasing the possibility of war between the two countries. In this tense situation, Great Britain worked to prevent a wider conflict by ending its seizure of American ships and offered to pay for captured cargoes. Hamilton saw an opportunity and recommended to Washington that the United States negotiate. Supreme Court Justice John Jay was sent to Britain, instructed by Hamilton to secure compensation for captured American ships; ensure the British leave the Northwest outposts they still occupied despite the 1783 Treaty of Paris; and gain an agreement for American trade in the West Indies. Even though Jay personally disliked slavery, his mission also required him to seek compensation from the British for self-emancipated enslaved people who left with the British at the end of the Revolutionary War. The resulting 1794 agreement, known as Jay’s Treaty, fulfilled most of his original goals. The British would turn over the frontier posts in the Northwest, American ships would be allowed to trade freely in the West Indies, and the United States agreed to assemble a commission charged with settling colonial debts U.S. citizens owed British merchants. The treaty did not address the important issue of impressment , however—the British navy’s practice of forcing or “impressing” American sailors to work and fight on British warships. Jay’s Treaty led the Spanish, who worried that it signaled an alliance between the United States and Great Britain, to negotiate a treaty of their own—Pinckney’s Treaty—that allowed American commerce to flow through the Spanish port of New Orleans. Pinckney’s Treaty allowed American farmers, who were moving in greater numbers to the Ohio River Valley, to ship their products down the Ohio and Mississippi Rivers to New Orleans, where they could be transported to East Coast markets. Jay’s Treaty confirmed the fears of Democratic-Republicans, who saw it as a betrayal of republican France, cementing the idea that the Federalists favored aristocracy and monarchy. Partisan American newspapers tried to sway public opinion, while the skillful writing of Hamilton, who published a number of essays on the subject, explained the benefits of commerce with Great Britain. THE FRENCH REVOLUTION’S CARIBBEAN LEGACY Unlike the American Revolution, which ultimately strengthened the institution of slavery and the powers of American slaveholders, the French Revolution inspired slave rebellions in the Caribbean, including a 1791 uprising in the French colony of Saint-Domingue (modern-day Haiti). Thousands of enslaved people joined together to overthrow the brutal system of slavery. They took control of a large section of the island, burning sugar plantations and killing the White people who had forced them to labor under the lash. In 1794, French revolutionaries abolished slavery in the French empire, and both Spain and England attacked Saint-Domingue, hoping to add the colony to their own empires. Toussaint L’Ouverture, who had been born with slave status was later freed, emerged as the leader in the fight against Spain and England to secure a Haiti free of slavery and further European colonialism. Because revolutionary France had abolished slavery, Toussaint aligned himself with France, hoping to keep Spain and England at bay ( Figure 8.6 ). Events in Haiti further complicated the partisan wrangling in the United States. White refugee planters from Haiti and other French West Indian islands, along with enslaved and free people of color, left the Caribbean for the United States and for Louisiana, which at the time was held by Spain. The presence of these French migrants raised fears, especially among Federalists, that they would bring the contagion of French radicalism to the United States. In addition, the idea that the French Revolution could inspire a successful slave uprising just off the American coastline filled southern Whites and slaveholders with horror. THE WHISKEY REBELLION While the wars in France and the Caribbean divided American citizens, a major domestic test of the new national government came in 1794 over the issue of a tax on whiskey, an important part of Hamilton’s financial program. In 1791, Congress had authorized a tax of 7.5 cents per gallon of whiskey and rum. Although most citizens paid without incident, trouble erupted in four western Pennsylvania counties in an uprising known as the Whiskey Rebellion. Farmers in the western counties of Pennsylvania produced whiskey from their grain for economic reasons. Without adequate roads or other means to transport a bulky grain harvest, these farmers distilled their grains into gin and whiskey, which were more cost-effective to transport. Since these farmers depended on the sale of whiskey, some citizens in western Pennsylvania (and elsewhere) viewed the new tax as further proof that the new national government favored the commercial classes on the eastern seaboard at the expense of farmers in the West. On the other hand, supporters of the tax argued that it helped stabilize the economy and its cost could easily be passed on to the consumer, not the farmer-distiller. However, in the spring and summer months of 1794, angry citizens rebelled against the federal officials in charge of enforcing the federal excise law. Like the Sons of Liberty before the American Revolution, the whiskey rebels used violence and intimidation to protest policies they saw as unfair. They tarred and feathered federal officials, intercepted the federal mail, and intimidated wealthy citizens. The extent of their discontent found expression in their plan to form an independent western commonwealth, and they even began negotiations with British and Spanish representatives, hoping to secure their support for independence from the United States. The rebels also contacted their backcountry neighbors in Kentucky and South Carolina, circulating the idea of secession. With their emphasis on personal freedoms, the whiskey rebels aligned themselves with the Democratic-Republican Party. They saw the tax as part of a larger Federalist plot to destroy their republican liberty and, in its most extreme interpretation, turn the United States into a monarchy. The federal government lowered the tax, but when federal officials tried to subpoena those distillers who remained intractable, trouble escalated. Washington responded by creating a thirteen-thousand-man militia, drawn from several states, to put down the rebellion ( Figure 8.7 ). This force made it known, both domestically and to the European powers that looked on in anticipation of the new republic’s collapse, that the national government would do everything in its power to ensure the survival of the United States. Defining American Alexander Hamilton: “Shall the majority govern or be governed?” Alexander Hamilton frequently wrote persuasive essays under pseudonyms, like “Tully,” as he does here. In this 1794 essay, Hamilton denounces the whiskey rebels and majority rule. It has been observed that the means most likely to be employed to turn the insurrection in the western country to the detriment of the government, would be artfully calculated among other things ‘to divert your attention from the true question to be decided.’ Let us see then what is this question. It is plainly this—shall the majority govern or be governed? shall the nation rule, or be ruled? shall the general will prevail, or the will of a faction? shall there be government, or no government? . . . The Constitution you have ordained for yourselves and your posterity contains this express clause, ‘The Congress shall have power to lay and collect taxes, duties, imposts, and Excises , to pay the debts, and provide for the common defence and general welfare of the United States.’ You have then, by a solemn and deliberate act, the most important and sacred that a nation can perform, pronounced and decreed, that your Representatives in Congress shall have power to lay Excises. You have done nothing since to reverse or impair that decree. . . . But the four western counties of Pennsylvania, undertake to rejudge and reverse your decrees, you have said, ‘The Congress shall have power to lay Excises .’ They say, ‘The Congress shall not have this power.’ . . . There is no road to despotism more sure or more to be dreaded than that which begins at anarchy .” —Alexander Hamilton’s “Tully No. II” for the American Daily Advertiser , Philadelphia, August 26, 1794 What are the major arguments put forward by Hamilton in this document? Who do you think his audience is? WASHINGTON’S NATIVE AMERICAN POLICY Relationships with Native Americans were a significant problem for Washington’s administration, but one on which White citizens agreed: Native Americans stood in the way of White settlement and, as the 1790 Naturalization Act made clear, were not citizens. After the War of Independence, White settlers poured into lands west of the Appalachian Mountains. As a result, from 1785 to 1795, a state of war existed on the frontier between these settlers and the Native Americans who lived in the Ohio territory. In both 1790 and 1791, the Shawnee and Miami had defended their lands against the Whites who arrived in greater and greater numbers from the East. In response, Washington appointed General Anthony Wayne to bring the Western Confederacy—a loose alliance of tribes—to heel. In 1794, at the Battle of Fallen Timbers, Wayne was victorious. With the 1795 Treaty of Greenville ( Figure 8.8 ), the Western Confederacy gave up their claims to Ohio. 8.3 Partisan Politics Learning Objectives By the end of this section, you will be able to: Identify key examples of partisan wrangling between the Federalists and Democratic-Republicans Describe how foreign relations affected American politics Assess the importance of the Louisiana Purchase George Washington, who had been reelected in 1792 by an overwhelming majority, refused to run for a third term, thus setting a precedent for future presidents. In the presidential election of 1796, the two parties—Federalist and Democratic-Republican—competed for the first time. Partisan rancor over the French Revolution and the Whiskey Rebellion fueled the divide between them, and Federalist John Adams defeated his Democratic-Republican rival Thomas Jefferson by a narrow margin of only three electoral votes. In 1800, another close election swung the other way, and Jefferson began a long period of Democratic-Republican government. THE PRESIDENCY OF JOHN ADAMS The war between Great Britain and France in the 1790s shaped U.S. foreign policy. As a new and, in comparison to the European powers, extremely weak nation, the American republic had no control over European events, and no real leverage to obtain its goals of trading freely in the Atlantic. To Federalist president John Adams, relations with France posed the biggest problem. After the Terror, the French Directory ruled France from 1795 to 1799. During this time, Napoleon rose to power. Americana The Art of Ralph Earl Ralph Earl was an eighteenth-century American artist, born in Massachusetts, who remained loyal to the British during the Revolutionary War. He fled to England in 1778, but he returned to New England in the mid-1780s and began painting portraits of leading Federalists. His portrait of Connecticut Federalist Oliver Ellsworth and his wife Abigail conveys the world as Federalists liked to view it: an orderly landscape administered by men of property and learning. His portrait of dry goods merchant Elijah Boardman shows Boardman as well-to-do and highly cultivated; his books include the works of Shakespeare and Milton ( Figure 8.9 ). What similarities do you see in the two portraits by Ralph Earl? What do the details of each portrait reveal about the sitters? About the artist and the 1790s? Because France and Great Britain were at war, the French Directory issued decrees stating that any ship carrying British goods could be seized on the high seas. In practice, this meant the French would target American ships, especially those in the West Indies, where the United States conducted a brisk trade with the British. France declared its 1778 treaty with the United States null and void, and as a result, France and the United States waged an undeclared war—or what historians refer to as the Quasi-War—from 1796 to 1800. Between 1797 and 1799, the French seized 834 American ships, and Adams urged the buildup of the U.S. Navy, which consisted of only a single vessel at the time of his election in 1796 ( Figure 8.10 ). In 1797, Adams sought a diplomatic solution to the conflict with France and dispatched envoys to negotiate terms. The French foreign minister, Charles-Maurice de Talleyrand, sent emissaries who told the American envoys that the United States must repay all outstanding debts owed to France, lend France 32 million guilders (Dutch currency), and pay a £50,000 bribe before any negotiations could take place. News of the attempt to extract a bribe, known as the XYZ affair because the French emissaries were referred to as X, Y, and Z in letters that President Adams released to Congress, outraged the American public and turned public opinion decidedly against France ( Figure 8.11 ). In the court of public opinion, Federalists appeared to have been correct in their interpretation of France, while the pro-French Democratic-Republicans had been misled. The complicated situation in Haiti, which remained a French colony in the late 1790s, also came to the attention of President Adams. The president, with the support of Congress, had created a U.S. Navy that now included scores of vessels. Most of the American ships cruised the Caribbean, giving the United States the edge over France in the region. In Haiti, the rebellion leader Toussaint, who had to contend with various domestic rivals seeking to displace him, looked to end an U.S. embargo on France and its colonies, put in place in 1798, so that his forces would receive help to deal with the civil unrest. In early 1799, in order to capitalize upon trade in the lucrative West Indies and undermine France’s hold on the island, Congress ended the ban on trade with Haiti—a move that acknowledged Toussaint’s leadership, to the horror of American slaveholders. Toussaint was able to secure an independent Black republic in Haiti by 1804. THE ALIEN AND SEDITION ACTS The surge of animosity against France during the Quasi-War led Congress to pass several measures that in time undermined Federalist power. These 1798 war measures, known as the Alien and Sedition Acts, aimed to increase national security against what most had come to regard as the French menace. The Alien Act and the Alien Enemies Act took particular aim at French immigrants fleeing the West Indies by giving the president the power to deport new arrivals who appeared to be a threat to national security. The act expired in 1800 with no immigrants having been deported. The Sedition Act imposed harsh penalties—up to five years’ imprisonment and a massive fine of $5,000 in 1790 dollars—on those convicted of speaking or writing “in a scandalous or malicious” manner against the government of the United States. Twenty-five men, all Democratic-Republicans, were indicted under the act, and ten were convicted. One of these was Congressman Matthew Lyon ( Figure 8.12 ), representative from Vermont, who had launched his own newspaper, The Scourge Of Aristocracy and Repository of Important Political Truth . The Alien and Sedition Acts raised constitutional questions about the freedom of the press provided under the First Amendment. Democratic-Republicans argued that the acts were evidence of the Federalists’ intent to squash individual liberties and, by enlarging the powers of the national government, crush states’ rights. Jefferson and Madison mobilized the response to the acts in the form of statements known as the Virginia and Kentucky Resolutions, which argued that the acts were illegal and unconstitutional. The resolutions introduced the idea of nullification, the right of states to nullify acts of Congress, and advanced the argument of states’ rights. The resolutions failed to rally support in other states, however. Indeed, most other states rejected them, citing the necessity of a strong national government. The Quasi-War with France came to an end in 1800, when President Adams was able to secure the Treaty of Mortefontaine. His willingness to open talks with France divided the Federalist Party, but the treaty reopened trade between the two countries and ended the French practice of taking American ships on the high seas. THE REVOLUTION OF 1800 AND THE PRESIDENCY OF THOMAS JEFFERSON The Revolution of 1800 refers to the first transfer of power from one party to another in American history, when the presidency passed to Democratic-Republican Thomas Jefferson ( Figure 8.13 ) in the 1800 election. The peaceful transition calmed contemporary fears about possible violent reactions to a new party’s taking the reins of government. The passing of political power from one political party to another without bloodshed also set an important precedent. The election did prove even more divisive than the 1796 election, however, as both the Federalist and Democratic-Republican Parties waged a mudslinging campaign unlike any seen before. Because the Federalists were badly divided, the Democratic-Republicans gained political ground. Alexander Hamilton, who disagreed with President Adams’s approach to France, wrote a lengthy letter, meant for people within his party, attacking his fellow Federalist’s character and judgment and ridiculing his handling of foreign affairs. Democratic-Republicans got hold of and happily reprinted the letter. Jefferson viewed participatory democracy as a positive force for the republic, a direct departure from Federalist views. His version of participatory democracy only extended, however, to the White yeoman farmers in whom Jefferson placed great trust. While Federalist statesmen, like the architects of the 1787 federal constitution, feared a pure democracy, Jefferson was far more optimistic that the common American farmer could be trusted to make good decisions. He believed in majority rule, that is, that the majority of yeoman should have the power to make decisions binding upon the whole. Jefferson had cheered the French Revolution, even when the French republic instituted the Terror to ensure the monarchy would not return. By 1799, however, he had rejected the cause of France because of his opposition to Napoleon’s seizure of power and creation of a dictatorship. Over the course of his two terms as president—he was reelected in 1804—Jefferson reversed the policies of the Federalist Party by turning away from urban commercial development. Instead, he promoted agriculture through the sale of western public lands in small and affordable lots. Perhaps Jefferson’s most lasting legacy is his vision of an “empire of liberty.” He distrusted cities and instead envisioned a rural republic of land-owning White men, or yeoman republican farmers. He wanted the United States to be the breadbasket of the world, exporting its agricultural commodities without suffering the ills of urbanization and industrialization. Since American yeomen would own their own land, they could stand up against those who might try to buy their votes with promises of property. Jefferson championed the rights of states and insisted on limited federal government as well as limited taxes. This stood in stark contrast to the Federalists’ insistence on a strong, active federal government. Jefferson also believed in fiscal austerity. He pushed for—and Congress approved—the end of all internal taxes, such as those on whiskey and rum. The most significant trimming of the federal budget came at the expense of the military; Jefferson did not believe in maintaining a costly military, and he slashed the size of the navy Adams had worked to build up. Nonetheless, Jefferson responded to the capture of American ships and sailors by pirates off the coast of North Africa by leading the United States into war against the Muslim Barbary States in 1801, the first conflict fought by Americans overseas. The slow decline of the Federalists, which began under Jefferson, led to a period of one-party rule in national politics. Historians call the years between 1815 and 1828 the “Era of Good Feelings” and highlight the “Virginia dynasty” of the time, since the two presidents who followed Jefferson—James Madison and James Monroe—both hailed from his home state. Like him, they were slaveholders and represented the Democratic-Republican Party. Though Federalists continued to enjoy popularity, especially in the Northeast, their days of prominence in setting foreign and domestic policy had ended. PARTISAN ACRIMONY The earliest years of the nineteenth century were hardly free of problems between the two political parties. Early in Jefferson’s term, controversy swirled over President Adams’s judicial appointments of many Federalists during his final days in office. When Jefferson took the oath of office, he refused to have the commissions for these Federalist justices delivered to the appointed officials. One of Adams’s appointees, William Marbury, had been selected to be a justice of the peace in the District of Columbia, and when his commission did not arrive, he petitioned the Supreme Court for an explanation from Jefferson’s secretary of state, James Madison. In deciding the case, Marbury v. Madison , in 1803, Chief Justice John Marshall agreed that Marbury had the right to a legal remedy, establishing that individuals had rights even the president of the United States could not abridge. However, Marshall also found that Congress’s Judicial Act of 1789, which would have given the Supreme Court the power to grant Marbury remedy, was unconstitutional because the Constitution did not allow for cases like Marbury’s to come directly before the Supreme Court. Thus, Marshall established the principle of judicial review, which strengthened the court by asserting its power to review (and possibly nullify) the actions of Congress and the president. Jefferson was not pleased, but neither did Marbury get his commission. The animosity between the political parties exploded into open violence in 1804, when Aaron Burr, Jefferson’s first vice president, and Alexander Hamilton engaged in a duel. When Democratic-Republican Burr lost his bid for the office of governor of New York, he was quick to blame Hamilton, who had long hated him and had done everything in his power to discredit him. On July 11, the two antagonists met in Weehawken, New Jersey, to exchange bullets in a duel in which Burr shot and mortally wounded Hamilton. THE LOUISIANA PURCHASE Jefferson, who wanted to expand the United States to bring about his “empire of liberty,” realized his greatest triumph in 1803 when the United States bought the Louisiana territory from France. For $15 million—a bargain price, considering the amount of land involved—the United States doubled in size. Perhaps the greatest real estate deal in American history, the Louisiana Purchase greatly enhanced the Jeffersonian vision of the United States as an agrarian republic in which yeomen farmers worked the land. Jefferson also wanted to bolster trade in the West, seeing the port of New Orleans and the Mississippi River (then the western boundary of the United States) as crucial to American agricultural commerce. In his mind, farmers would send their produce down the Mississippi River to New Orleans, where it would be sold to European traders. The purchase of Louisiana came about largely because of circumstances beyond Jefferson’s control, though he certainly recognized the implications of the transaction. Until 1801, Spain had controlled New Orleans and had given the United States the right to traffic goods in the port without paying customs duties. That year, however, the Spanish had ceded Louisiana (and New Orleans) to France. In 1802, the United States lost its right to deposit goods free in the port, causing outrage among many, some of whom called for war with France. Jefferson instructed Robert Livingston, the American envoy to France, to secure access to New Orleans, sending James Monroe to France to add additional pressure. The timing proved advantageous. Because enslaved Black people in the French colony of Haiti had successfully overthrown the brutal plantation regime, Napoleon could no longer hope to restore the empire lost with France’s defeat in the French and Indian War (1754–1763). His vision of Louisiana and the Mississippi Valley as the source for food for Haiti, the most profitable sugar island in the world, had failed. The emperor therefore agreed to the sale in early 1803. The true extent of the United States’ new territory remained unknown ( Figure 8.14 ). Would it provide the long-sought quick access to Asian markets? Geographical knowledge was limited; indeed, no one knew precisely what lay to the west or how long it took to travel from the Mississippi to the Pacific. Jefferson selected two fellow Virginians, Meriwether Lewis and William Clark, to lead an expedition to the new western lands. Their purpose was to discover the commercial possibilities of the new land and, most importantly, potential trade routes. From 1804 to 1806, Lewis and Clark traversed the West. The Louisiana Purchase helped Jefferson win reelection in 1804 by a landslide. Of 176 electoral votes cast, all but 14 were in his favor. The great expansion of the United States did have its critics, however, especially northerners who feared the addition of more slave states and a corresponding lack of representation of their interests in the North. And under a strict interpretation of the Constitution, it remained unclear whether the president had the power to add territory in this fashion. But the vast majority of citizens cheered the increase in the size of the republic. For slaveholders, new western lands would be a boon; for their captives, the Louisiana Purchase threatened to entrench their suffering further. 8.4 The United States Goes Back to War Learning Objectives By the end of this section, you will be able to: Describe the causes and consequences of the War of 1812 Identify the important events of the War of 1812 and explain their significance The origins of the War of 1812, often called the Second War of American Independence, are found in the unresolved issues between the United States and Great Britain. One major cause was the British practice of impressment, whereby American sailors were taken at sea and forced to fight on British warships; this issue was left unresolved by Jay’s Treaty in 1794. In addition, the British in Canada supported Native Americans in their fight against further U.S. expansion in the Great Lakes region. Though Jefferson wanted to avoid what he called “entangling alliances,” staying neutral proved impossible. THE EMBARGO OF 1807 France and England, engaged in the Napoleonic Wars, which raged between 1803 and 1815, both declared open season on American ships, which they seized on the high seas. England was the major offender, since the Royal Navy, following a time-honored practice, “impressed” American sailors by forcing them into its service. The issue came to a head in 1807 when the HMS Leopard , a British warship, fired on a U.S. naval ship, the Chesapeake , off the coast of Norfolk, Virginia. The British then boarded the ship and took four sailors. Jefferson chose what he thought was the best of his limited options and responded to the crisis through the economic means of a sweeping ban on trade, the Embargo Act of 1807 . This law prohibited American ships from leaving their ports until Britain and France stopped seizing them on the high seas. As a result of the embargo, American commerce came to a near-total halt. The logic behind the embargo was that cutting off all trade would so severely hurt Britain and France that the seizures at sea would end. However, while the embargo did have some effect on the British economy, it was American commerce that actually felt the brunt of the impact ( Figure 8.15 ). The embargo hurt American farmers, who could no longer sell their goods overseas, and seaport cities experienced a huge increase in unemployment and an uptick in bankruptcies. All told, American business activity declined by 75 percent from 1808 to 1809. Enforcement of the embargo proved very difficult, especially in the states bordering British Canada. Smuggling was widespread; Smugglers’ Notch in Vermont, for example, earned its name from illegal trade with British Canada. Jefferson attributed the problems with the embargo to lax enforcement. At the very end of his second term, Jefferson signed the Non-Intercourse Act of 1808, lifting the unpopular embargoes on trade except with Britain and France. In the election of 1808, American voters elected another Democratic-Republican, James Madison. Madison inherited Jefferson’s foreign policy issues involving Britain and France. Most people in the United States, especially those in the West, saw Great Britain as the major problem. TECUMSEH AND THE WESTERN CONFEDERACY Another underlying cause of the War of 1812 was British support for native resistance to U.S. western expansion. For many years, White settlers in the American western territories had besieged the Native Americans living there. Under Jefferson, two policies existed: forcing Native Americans to adopt American ways of agricultural life, or aggressively driving them into debt in order to force them to sell their lands. In 1809, Tecumseh, a Shawnee war chief, rejuvenated the Western Confederacy. His brother, Tenskwatawa, was a prophet among the Shawnee who urged a revival of native ways and rejection of Anglo-American culture, including alcohol. In 1811, William Henry Harrison, the governor of the Indiana Territory, attempted to eliminate the native presence by attacking Prophetstown, a Shawnee settlement named in honor of Tenskwatawa. In the ensuing Battle of Tippecanoe, U.S. forces led by Harrison destroyed the settlement ( Figure 8.16 ). They also found ample evidence that the British had supplied the Western Confederacy with weapons, despite the stipulations of earlier treaties. THE WAR OF 1812 The seizure of American ships and sailors, combined with the British support of Native American resistance, led to strident calls for war against Great Britain. The loudest came from the “war hawks,” led by Henry Clay from Kentucky and John C. Calhoun from South Carolina, who would not tolerate British insults to American honor. Opposition to the war came from Federalists, especially those in the Northeast, who knew war would disrupt the maritime trade on which they depended. In a narrow vote, Congress authorized the president to declare war against Britain in June 1812. The war went very badly for the United States at first. In August 1812, the United States lost Detroit to the British and their Native allies, including a force of one thousand men led by Tecumseh. By the end of the year, the British controlled half the Northwest. The following year, however, U.S. forces scored several victories. Captain Oliver Hazard Perry and his naval force defeated the British on Lake Erie. At the Battle of the Thames in Ontario, the United States defeated the British and their native allies, and Tecumseh was counted among the dead. Native American resistance began to ebb, opening the Indiana and Michigan territories for White settlement. These victories could not turn the tide of the war, however. With the British gaining the upper hand during the Napoleonic Wars and Napoleon’s French army on the run, Great Britain now could divert skilled combat troops from Europe to fight in the United States. In July 1814, forty-five hundred hardened British soldiers sailed up the Chesapeake Bay and burned Washington, DC, to the ground, forcing President Madison and his wife to run for their lives ( Figure 8.17 ). According to one report, they left behind a dinner the British officers ate. That summer, the British shelled Baltimore, hoping for another victory. However, they failed to dislodge the U.S. forces, whose survival of the bombardment inspired Francis Scott Key to write “The Star-Spangled Banner.” Americana Francis Scott Key’s “In Defense of Fort McHenry” After the British bombed Baltimore’s Fort McHenry in 1814 but failed to overcome the U.S. forces there, Francis Scott Key was inspired by the sight of the American flag, which remained hanging proudly in the aftermath. He wrote the poem “In Defense of Fort McHenry,” which was later set to the tune of a British song called “The Anacreontic Song” and eventually became the U.S. national anthem, “The Star-Spangled Banner.” Oh, say, can you see, by the dawn’s early light, What so proudly we hailed at the twilight’s last gleaming? Whose broad stripes and bright stars, thru the perilous fight, O’er the ramparts we watched, were so gallantly streaming? And the rockets’ red glare, the bombs bursting in air, Gave proof through the night that our flag was still there. O say, does that star-spangled banner yet wave O’er the land of the free and the home of the brave? On the shore dimly seen through the mists of the deep, Where the foe’s haughty host in dread silence reposes, What is that which the breeze, o’er the towering steep, As it fitfully blows, half conceals, half discloses? Now it catches the gleam of the morning’s first beam, In full glory reflected, now shines on the stream: Tis the star-spangled banner: O, long may it wave O’er the land of the free and the home of the brave! And where is that band who so vauntingly swore That the havoc of war and the battle’s confusion A home and a country should leave us no more? Their blood has washed out their foul footsteps’ pollution. No refuge could save the hireling and slave From the terror of flight or the gloom of the grave: And the star-spangled banner in triumph doth wave O’er the land of the free and the home of the brave. O, thus be it ever when freemen shall stand, Between their loved home and the war’s desolation! Blest with victory and peace, may the heav’n-rescued land Praise the Power that hath made and preserved us a nation! Then conquer we must, when our cause it is just, And this be our motto: “In God is our trust” And the star-spangled banner in triumph shall wave O’er the land of the free and the home of the brave! —Francis Scott Key, “In Defense of Fort McHenry,” 1814 What images does Key use to describe the American spirit? Most people are familiar with only the first verse of the song; what do you think the last three verses add? With the end of the war in Europe, Britain was eager to end the conflict in the Americas as well. In 1814, British and U.S. diplomats met in Flanders, in northern Belgium, to negotiate the Treaty of Ghent, signed in December. The boundaries between the United States and British Canada remained as they were before the war, an outcome welcome to those in the United States who feared a rupture in the country’s otherwise steady expansion into the West. The War of 1812 was very unpopular in New England because it inflicted further economic harm on a region dependent on maritime commerce. This unpopularity caused a resurgence of the Federalist Party in New England. Many Federalists deeply resented the power of the slaveholding Virginians (Jefferson and then Madison), who appeared indifferent to their region. The depth of the Federalists’ discontent is illustrated by the proceedings of the December 1814 Hartford Convention, a meeting of twenty-six Federalists in Connecticut, where some attendees issued calls for New England to secede from the United States. These arguments for disunion during wartime, combined with the convention’s condemnation of the government, made Federalists appear unpatriotic. The convention forever discredited the Federalist Party and led to its downfall. EPILOGUE: THE BATTLE OF NEW ORLEANS Due to slow communication, the last battle in the War of 1812 happened after the Treaty of Ghent had been signed ending the war. Andrew Jackson had distinguished himself in the war by defeating the Creek Natives in March 1814 before invading Florida in May of that year. After taking Pensacola, he moved his force of Tennessee fighters to New Orleans to defend the strategic port against British attack. On January 8, 1815 (despite the official end of the war), a force of battle-tested British veterans of the Napoleonic Wars attempted to take the port. Jackson’s forces devastated the British, killing over two thousand. New Orleans and the vast Mississippi River Valley had been successfully defended, ensuring the future of American settlement and commerce. The Battle of New Orleans immediately catapulted Jackson to national prominence as a war hero, and in the 1820s, he emerged as the head of the new Democratic Party.
anatomy_and_physiology
Chapter Objectives After studying this chapter, you will be able to: Describe the actions and roles of agonists and antagonists Explain the structure and organization of muscle fascicles and their role in generating force Explain the criteria used to name skeletal muscles Identify the skeletal muscles and their actions on the skeleton and soft tissues of the body Identify the origins and insertions of skeletal muscles and the prime movements Introduction Think about the things that you do each day—talking, walking, sitting, standing, and running—all of these activities require movement of particular skeletal muscles. Skeletal muscles are even used during sleep. The diaphragm is a sheet of skeletal muscle that has to contract and relax for you to breathe day and night. If you recall from your study of the skeletal system and joints, body movement occurs around the joints in the body. The focus of this chapter is on skeletal muscle organization. The system to name skeletal muscles will be explained; in some cases, the muscle is named by its shape, and in other cases it is named by its location or attachments to the skeleton. If you understand the meaning of the name of the muscle, often it will help you remember its location and/or what it does. This chapter also will describe how skeletal muscles are arranged to accomplish movement, and how other muscles may assist, or be arranged on the skeleton to resist or carry out the opposite movement. The actions of the skeletal muscles will be covered in a regional manner, working from the head down to the toes.
[ { "answer": { "ans_choice": 3, "ans_text": "They insert into the skin." }, "bloom": null, "hl_context": "The origins of the muscles of facial expression are on the surface of the skull ( remember , the origin of a muscle does not move ) . <hl> The insertions of these muscles have fibers intertwined with connective tissue and the dermis of the skin . <hl> <hl> Because the muscles insert in the skin rather than on bone , when they contract , the skin moves to create facial expression ( Figure 11.7 ) . <hl>", "hl_sentences": "The insertions of these muscles have fibers intertwined with connective tissue and the dermis of the skin . Because the muscles insert in the skin rather than on bone , when they contract , the skin moves to create facial expression ( Figure 11.7 ) .", "question": { "cloze_format": "To the muscles of facial expression, it is unique that ___ .", "normal_format": "Which of the following is unique to the muscles of facial expression?", "question_choices": [ "They all originate from the scalp musculature.", "They insert onto the cartilage found around the face.", "They only insert onto the facial bones.", "They insert into the skin." ], "question_id": "fs-id2595266", "question_text": "Which of the following is unique to the muscles of facial expression?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 0, "ans_text": "a synergist" }, "bloom": "1", "hl_context": "<hl> Although a number of muscles may be involved in an action , the principal muscle involved is called the prime mover , or agonist . <hl> <hl> To lift a cup , a muscle called the biceps brachii is actually the prime mover ; however , because it can be assisted by the brachialis , the brachialis is called a synergist in this action ( Figure 11.2 ) . <hl> A synergist can also be a fixator that stabilizes the bone that is the attachment for the prime mover ’ s origin .", "hl_sentences": "Although a number of muscles may be involved in an action , the principal muscle involved is called the prime mover , or agonist . To lift a cup , a muscle called the biceps brachii is actually the prime mover ; however , because it can be assisted by the brachialis , the brachialis is called a synergist in this action ( Figure 11.2 ) .", "question": { "cloze_format": "___ helps an agonist work.", "normal_format": "Which of the following helps an agonist work?", "question_choices": [ "a synergist", "a fixator", "an insertion", "an antagonist" ], "question_id": "fs-id2761928", "question_text": "Which of the following helps an agonist work?" }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 1, "ans_text": "The angle between bones is decreased." }, "bloom": "1", "hl_context": "The location of a muscle ’ s attachment can also appear in its name . When the name of a muscle is based on the attachments , the origin is always named first . For instance , the sternocleidomastoid muscle of the neck has a dual origin on the sternum ( sterno ) and clavicle ( cleido ) , and it inserts on the mastoid process of the temporal bone . The last feature by which to name a muscle is its action . When muscles are named for the movement they produce , one can find action words in their name . <hl> Some examples are flexor ( decreases the angle at the joint ) , extensor ( increases the angle at the joint ) , abductor ( moves the bone away from the midline ) , or adductor ( moves the bone toward the midline ) . <hl> 11.3 Axial Muscles of the Head , Neck , and Back Learning Objectives By the end of this section , you will be able to :", "hl_sentences": "Some examples are flexor ( decreases the angle at the joint ) , extensor ( increases the angle at the joint ) , abductor ( moves the bone away from the midline ) , or adductor ( moves the bone toward the midline ) .", "question": { "cloze_format": "The statement that is correct about what happens during flexion is ___.", "normal_format": "Which of the following statements is correct about what happens during flexion?", "question_choices": [ "The angle between bones is increased.", "The angle between bones is decreased.", "The bone moves away from the body.", "The bone moves toward the center of the body." ], "question_id": "fs-id2874612", "question_text": "Which of the following statements is correct about what happens during flexion?" }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 0, "ans_text": "the origin" }, "bloom": null, "hl_context": "<hl> The origins of the muscles of facial expression are on the surface of the skull ( remember , the origin of a muscle does not move ) . <hl> The insertions of these muscles have fibers intertwined with connective tissue and the dermis of the skin . Because the muscles insert in the skin rather than on bone , when they contract , the skin moves to create facial expression ( Figure 11.7 ) .", "hl_sentences": "The origins of the muscles of facial expression are on the surface of the skull ( remember , the origin of a muscle does not move ) .", "question": { "cloze_format": "___ are moved the least during muscle contraction.", "normal_format": "Which is moved the least during muscle contraction?", "question_choices": [ "the origin", "the insertion", "the ligaments", "the joints" ], "question_id": "fs-id2109061", "question_text": "Which is moved the least during muscle contraction?" }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 2, "ans_text": "pectoralis major" }, "bloom": "1", "hl_context": "<hl> When a muscle has a widespread expansion over a sizable area , but then the fascicles come to a single , common attachment point , the muscle is called convergent . <hl> The attachment point for a convergent muscle could be a tendon , an aponeurosis ( a flat , broad tendon ) , or a raphe ( a very slender tendon ) . <hl> The large muscle on the chest , the pectoralis major , is an example of a convergent muscle because it converges on the greater tubercle of the humerus via a tendon . <hl> The temporalis muscle of the cranium is another .", "hl_sentences": "When a muscle has a widespread expansion over a sizable area , but then the fascicles come to a single , common attachment point , the muscle is called convergent . The large muscle on the chest , the pectoralis major , is an example of a convergent muscle because it converges on the greater tubercle of the humerus via a tendon .", "question": { "cloze_format": "___ is a muscle that has a convergent pattern of fascicles.", "normal_format": "Which muscle has a convergent pattern of fascicles?", "question_choices": [ "biceps brachii", "gluteus maximus", "pectoralis major", "rectus femoris" ], "question_id": "fs-id2361712", "question_text": "Which muscle has a convergent pattern of fascicles?" }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 2, "ans_text": "parallel" }, "bloom": null, "hl_context": "<hl> Parallel muscles have fascicles that are arranged in the same direction as the long axis of the muscle ( Figure 11.3 ) . <hl> The majority of skeletal muscles in the body have this type of organization . Some parallel muscles are flat sheets that expand at the ends to make broad attachments . Other parallel muscles are rotund with tendons at one or both ends . Muscles that seem to be plump have a large mass of tissue located in the middle of the muscle , between the insertion and the origin , which is known as the central body . A more common name for this muscle is belly . When a muscle contracts , the contractile fibers shorten it to an even larger bulge . For example , extend and then flex your biceps brachii muscle ; the large , middle section is the belly ( Figure 11.4 ) . When a parallel muscle has a central , large belly that is spindle-shaped , meaning it tapers as it extends to its origin and insertion , it sometimes is called fusiform .", "hl_sentences": "Parallel muscles have fascicles that are arranged in the same direction as the long axis of the muscle ( Figure 11.3 ) .", "question": { "cloze_format": "A muscle that has a pattern of fascicles running along the long axis of the muscle has ___ fascicle arrangements.", "normal_format": "A muscle that has a pattern of fascicles running along the long axis of the muscle has which of the following fascicle arrangements?", "question_choices": [ "circular", "pennate", "parallel", "rectus" ], "question_id": "fs-id2790910", "question_text": "A muscle that has a pattern of fascicles running along the long axis of the muscle has which of the following fascicle arrangements?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 0, "ans_text": "The muscle fibers feed in on an angle to a long tendon from both sides." }, "bloom": "4", "hl_context": "In a unipennate muscle , the fascicles are located on one side of the tendon . The extensor digitorum of the forearm is an example of a unipennate muscle . <hl> A bipennate muscle has fascicles on both sides of the tendon . <hl> In some pennate muscles , the muscle fibers wrap around the tendon , sometimes forming individual fascicles in the process . This arrangement is referred to as multipennate . A common example is the deltoid muscle of the shoulder , which covers the shoulder but has a single tendon that inserts on the deltoid tuberosity of the humerus . <hl> Pennate muscles ( penna = “ feathers ” ) blend into a tendon that runs through the central region of the muscle for its whole length , somewhat like the quill of a feather with the muscle arranged similar to the feathers . <hl> <hl> Due to this design , the muscle fibers in a pennate muscle can only pull at an angle , and as a result , contracting pennate muscles do not move their tendons very far . <hl> However , because a pennate muscle generally can hold more muscle fibers within it , it can produce relatively more tension for its size . <hl> There are three subtypes of pennate muscles . <hl>", "hl_sentences": "A bipennate muscle has fascicles on both sides of the tendon . Pennate muscles ( penna = “ feathers ” ) blend into a tendon that runs through the central region of the muscle for its whole length , somewhat like the quill of a feather with the muscle arranged similar to the feathers . Due to this design , the muscle fibers in a pennate muscle can only pull at an angle , and as a result , contracting pennate muscles do not move their tendons very far . There are three subtypes of pennate muscles .", "question": { "cloze_format": "The arrangement that best describes a bipennate muscle is that ___.", "normal_format": "Which arrangement best describes a bipennate muscle?", "question_choices": [ "The muscle fibers feed in on an angle to a long tendon from both sides.", "The muscle fibers feed in on an angle to a long tendon from all directions.", "The muscle fibers feed in on an angle to a long tendon from one side.", "The muscle fibers on one side of a tendon feed into it at a certain angle and muscle fibers on the other side of the tendon feed into it at the opposite angle." ], "question_id": "fs-id3088365", "question_text": "Which arrangement best describes a bipennate muscle?" }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 0, "ans_text": "action" }, "bloom": "1", "hl_context": "The location of a muscle ’ s attachment can also appear in its name . <hl> When the name of a muscle is based on the attachments , the origin is always named first . <hl> For instance , the sternocleidomastoid muscle of the neck has a dual origin on the sternum ( sterno ) and clavicle ( cleido ) , and it inserts on the mastoid process of the temporal bone . <hl> The last feature by which to name a muscle is its action . <hl> <hl> When muscles are named for the movement they produce , one can find action words in their name . <hl> Some examples are flexor ( decreases the angle at the joint ) , extensor ( increases the angle at the joint ) , abductor ( moves the bone away from the midline ) , or adductor ( moves the bone toward the midline ) . 11.3 Axial Muscles of the Head , Neck , and Back Learning Objectives By the end of this section , you will be able to : To pull on a bone , that is , to change the angle at its synovial joint , which essentially moves the skeleton , a skeletal muscle must also be attached to a fixed part of the skeleton . <hl> The moveable end of the muscle that attaches to the bone being pulled is called the muscle ’ s insertion , and the end of the muscle attached to a fixed ( stabilized ) bone is called the origin . <hl> During forearm flexion — bending the elbow — the brachioradialis assists the brachialis .", "hl_sentences": "When the name of a muscle is based on the attachments , the origin is always named first . The last feature by which to name a muscle is its action . When muscles are named for the movement they produce , one can find action words in their name . The moveable end of the muscle that attaches to the bone being pulled is called the muscle ’ s insertion , and the end of the muscle attached to a fixed ( stabilized ) bone is called the origin .", "question": { "cloze_format": "The location of a muscle’s insertion and origin can determine ________.", "normal_format": "The location of a muscle’s insertion and origin can determine what?", "question_choices": [ "action", "the force of contraction", "muscle name", "the load a muscle can carry" ], "question_id": "fs-id4354529", "question_text": "The location of a muscle’s insertion and origin can determine ________." }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 2, "ans_text": "on the side of the head" }, "bloom": null, "hl_context": "In anatomical terminology , chewing is called mastication . Muscles involved in chewing must be able to exert enough pressure to bite through and then chew food before it is swallowed ( Figure 11.10 and Table 11.4 ) . <hl> The masseter muscle is the main muscle used for chewing because it elevates the mandible ( lower jaw ) to close the mouth , and it is assisted by the temporalis muscle , which retracts the mandible . <hl> <hl> You can feel the temporalis move by putting your fingers to your temple as you chew . <hl> Muscles of the Lower Jaw", "hl_sentences": "The masseter muscle is the main muscle used for chewing because it elevates the mandible ( lower jaw ) to close the mouth , and it is assisted by the temporalis muscle , which retracts the mandible . You can feel the temporalis move by putting your fingers to your temple as you chew .", "question": { "cloze_format": "The temporalis muscle is located ___ .", "normal_format": "Where is the temporalis muscle located?", "question_choices": [ "on the forehead", "in the neck", "on the side of the head", "on the chin" ], "question_id": "fs-id2525672", "question_text": "Where is the temporalis muscle located?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 3, "ans_text": "extensor minimus longus" }, "bloom": "1", "hl_context": "The location of a muscle ’ s attachment can also appear in its name . <hl> When the name of a muscle is based on the attachments , the origin is always named first . <hl> For instance , the sternocleidomastoid muscle of the neck has a dual origin on the sternum ( sterno ) and clavicle ( cleido ) , and it inserts on the mastoid process of the temporal bone . <hl> The last feature by which to name a muscle is its action . <hl> <hl> When muscles are named for the movement they produce , one can find action words in their name . <hl> <hl> Some examples are flexor ( decreases the angle at the joint ) , extensor ( increases the angle at the joint ) , abductor ( moves the bone away from the midline ) , or adductor ( moves the bone toward the midline ) . <hl> 11.3 Axial Muscles of the Head , Neck , and Back Learning Objectives By the end of this section , you will be able to : The skeletal muscle ’ s anatomical location or its relationship to a particular bone often determines its name . For example , the frontalis muscle is located on top of the frontal bone of the skull . Similarly , the shapes of some muscles are very distinctive and the names , such as orbicularis , reflect the shape . <hl> For the buttocks , the size of the muscles influences the names : gluteus maximus ( largest ) , gluteus medius ( medium ) , and the gluteus minimus ( smallest ) . <hl> <hl> Names were given to indicate length — brevis ( short ) , longus ( long ) — and to identify position relative to the midline : lateralis ( to the outside away from the midline ) , and medialis ( toward the midline ) . <hl> <hl> The direction of the muscle fibers and fascicles are used to describe muscles relative to the midline , such as the rectus ( straight ) abdominis , or the oblique ( at an angle ) muscles of the abdomen . <hl>", "hl_sentences": "When the name of a muscle is based on the attachments , the origin is always named first . The last feature by which to name a muscle is its action . When muscles are named for the movement they produce , one can find action words in their name . Some examples are flexor ( decreases the angle at the joint ) , extensor ( increases the angle at the joint ) , abductor ( moves the bone away from the midline ) , or adductor ( moves the bone toward the midline ) . For the buttocks , the size of the muscles influences the names : gluteus maximus ( largest ) , gluteus medius ( medium ) , and the gluteus minimus ( smallest ) . Names were given to indicate length — brevis ( short ) , longus ( long ) — and to identify position relative to the midline : lateralis ( to the outside away from the midline ) , and medialis ( toward the midline ) . The direction of the muscle fibers and fascicles are used to describe muscles relative to the midline , such as the rectus ( straight ) abdominis , or the oblique ( at an angle ) muscles of the abdomen .", "question": { "cloze_format": "The muscle name that does not make sense is ___ .", "normal_format": "Which muscle name does not make sense?", "question_choices": [ "extensor digitorum", "gluteus minimus", "biceps femoris", "extensor minimus longus" ], "question_id": "fs-id21090610", "question_text": "Which muscle name does not make sense?" }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 1, "ans_text": "adductor" }, "bloom": null, "hl_context": "The location of a muscle ’ s attachment can also appear in its name . When the name of a muscle is based on the attachments , the origin is always named first . For instance , the sternocleidomastoid muscle of the neck has a dual origin on the sternum ( sterno ) and clavicle ( cleido ) , and it inserts on the mastoid process of the temporal bone . The last feature by which to name a muscle is its action . When muscles are named for the movement they produce , one can find action words in their name . <hl> Some examples are flexor ( decreases the angle at the joint ) , extensor ( increases the angle at the joint ) , abductor ( moves the bone away from the midline ) , or adductor ( moves the bone toward the midline ) . <hl> 11.3 Axial Muscles of the Head , Neck , and Back Learning Objectives By the end of this section , you will be able to :", "hl_sentences": "Some examples are flexor ( decreases the angle at the joint ) , extensor ( increases the angle at the joint ) , abductor ( moves the bone away from the midline ) , or adductor ( moves the bone toward the midline ) .", "question": { "cloze_format": "The term that would be used in the name of a muscle that moves the leg away from the body is ___.", "normal_format": "Which of the following terms would be used in the name of a muscle that moves the leg away from the body?", "question_choices": [ "flexor", "adductor", "extensor", "abductor" ], "question_id": "fs-id2365924", "question_text": "Which of the following terms would be used in the name of a muscle that moves the leg away from the body?" }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 2, "ans_text": "sternocleidomastoid" }, "bloom": null, "hl_context": "The head , attached to the top of the vertebral column , is balanced , moved , and rotated by the neck muscles ( Table 11.5 ) . When these muscles act unilaterally , the head rotates . When they contract bilaterally , the head flexes or extends . <hl> The major muscle that laterally flexes and rotates the head is the sternocleidomastoid . <hl> In addition , both muscles working together are the flexors of the head . Place your fingers on both sides of the neck and turn your head to the left and to the right . You will feel the movement originate there . This muscle divides the neck into anterior and posterior triangles when viewed from the side ( Figure 11.14 ) . Muscles That Move the Head", "hl_sentences": "The major muscle that laterally flexes and rotates the head is the sternocleidomastoid .", "question": { "cloze_format": "The ___ is a prime mover in head flexion.", "normal_format": "Which of the following is a prime mover in head flexion?", "question_choices": [ "occipitofrontalis", "corrugator supercilii", "sternocleidomastoid", "masseter" ], "question_id": "fs-id1516671", "question_text": "Which of the following is a prime mover in head flexion?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 1, "ans_text": "in the eye socket" }, "bloom": "1", "hl_context": "<hl> Inferior oblique <hl> <hl> The movement of the eyeball is under the control of the extrinsic eye muscles , which originate outside the eye and insert onto the outer surface of the white of the eye . <hl> <hl> These muscles are located inside the eye socket and cannot be seen on any part of the visible eyeball ( Figure 11.9 and Table 11.3 ) . <hl> If you have ever been to a doctor who held up a finger and asked you to follow it up , down , and to both sides , he or she is checking to make sure your eye muscles are acting in a coordinated pattern . <hl> Muscles of the Eyes <hl>", "hl_sentences": "Inferior oblique The movement of the eyeball is under the control of the extrinsic eye muscles , which originate outside the eye and insert onto the outer surface of the white of the eye . These muscles are located inside the eye socket and cannot be seen on any part of the visible eyeball ( Figure 11.9 and Table 11.3 ) . Muscles of the Eyes", "question": { "cloze_format": "The inferior oblique muscle is located ___ .", "normal_format": "Where is the inferior oblique muscle located?", "question_choices": [ "in the abdomen", "in the eye socket", "in the anterior neck", "in the face" ], "question_id": "fs-id2017162", "question_text": "Where is the inferior oblique muscle located?" }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 1, "ans_text": "chewing" }, "bloom": null, "hl_context": "In anatomical terminology , chewing is called mastication . Muscles involved in chewing must be able to exert enough pressure to bite through and then chew food before it is swallowed ( Figure 11.10 and Table 11.4 ) . <hl> The masseter muscle is the main muscle used for chewing because it elevates the mandible ( lower jaw ) to close the mouth , and it is assisted by the temporalis muscle , which retracts the mandible . <hl> You can feel the temporalis move by putting your fingers to your temple as you chew . Muscles of the Lower Jaw", "hl_sentences": "The masseter muscle is the main muscle used for chewing because it elevates the mandible ( lower jaw ) to close the mouth , and it is assisted by the temporalis muscle , which retracts the mandible .", "question": { "cloze_format": "___ is the action of the masseter.", "normal_format": "What is the action of the masseter?", "question_choices": [ "swallowing", "chewing", "moving the lips", "closing the eye" ], "question_id": "fs-id2261272", "question_text": "What is the action of the masseter?" }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 1, "ans_text": "-glossus" }, "bloom": "1", "hl_context": "<hl> The extrinsic muscles all include the word root glossus ( glossus = “ tongue ” ) , and the muscle names are derived from where the muscle originates . <hl> The genioglossus ( genio = “ chin ” ) originates on the mandible and allows the tongue to move downward and forward . The styloglossus originates on the styloid bone , and allows upward and backward motion . The palatoglossus originates on the soft palate to elevate the back of the tongue , and the hyoglossus originates on the hyoid bone to move the tongue downward and flatten it .", "hl_sentences": "The extrinsic muscles all include the word root glossus ( glossus = “ tongue ” ) , and the muscle names are derived from where the muscle originates .", "question": { "cloze_format": "The names of the extrinsic tongue muscles commonly end in ________.", "normal_format": "What do the names of the extrinsic tongue muscles commonly end in?", "question_choices": [ "-glottis", "-glossus", "-gluteus", "-hyoid" ], "question_id": "fs-id2493246", "question_text": "The names of the extrinsic tongue muscles commonly end in ________." }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 2, "ans_text": "postural support" }, "bloom": "1", "hl_context": "<hl> It is a complex job to balance the body on two feet and walk upright . <hl> <hl> The muscles of the vertebral column , thorax , and abdominal wall extend , flex , and stabilize different parts of the body ’ s trunk . <hl> <hl> The deep muscles of the core of the body help maintain posture as well as carry out other functions . <hl> The brain sends out electrical impulses to these various muscle groups to control posture by alternate contraction and relaxation . This is necessary so that no single muscle group becomes fatigued too quickly . If any one group fails to function , body posture will be compromised . The splenius muscles originate at the midline and run laterally and superiorly to their insertions . From the sides and the back of the neck , the splenius capitis inserts onto the head region , and the splenius cervicis extends onto the cervical region . These muscles can extend the head , laterally flex it , and rotate it ( Figure 11.15 ) . <hl> The erector spinae group forms the majority of the muscle mass of the back and it is the primary extensor of the vertebral column . <hl> <hl> It controls flexion , lateral flexion , and rotation of the vertebral column , and maintains the lumbar curve . <hl> The erector spinae comprises the iliocostalis ( laterally placed ) group , the longissimus ( intermediately placed ) group , and the spinalis ( medially placed ) group .", "hl_sentences": "It is a complex job to balance the body on two feet and walk upright . The muscles of the vertebral column , thorax , and abdominal wall extend , flex , and stabilize different parts of the body ’ s trunk . The deep muscles of the core of the body help maintain posture as well as carry out other functions . The erector spinae group forms the majority of the muscle mass of the back and it is the primary extensor of the vertebral column . It controls flexion , lateral flexion , and rotation of the vertebral column , and maintains the lumbar curve .", "question": { "cloze_format": "The function of the erector spinae is ___.", "normal_format": "What is the function of the erector spinae?", "question_choices": [ "movement of the arms", "stabilization of the pelvic girdle", "postural support", "rotating of the vertebral column" ], "question_id": "fs-id2471871", "question_text": "What is the function of the erector spinae?" }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 0, "ans_text": "quadratus lumborum" }, "bloom": "1", "hl_context": "<hl> There are four pairs of abdominal muscles that cover the anterior and lateral abdominal region and meet at the anterior midline . <hl> <hl> These muscles of the anterolateral abdominal wall can be divided into four groups : the external obliques , the internal obliques , the transversus abdominis , and the rectus abdominis ( Figure 11.16 and Table 11.6 ) . <hl> Muscles of the Abdomen", "hl_sentences": "There are four pairs of abdominal muscles that cover the anterior and lateral abdominal region and meet at the anterior midline . These muscles of the anterolateral abdominal wall can be divided into four groups : the external obliques , the internal obliques , the transversus abdominis , and the rectus abdominis ( Figure 11.16 and Table 11.6 ) .", "question": { "cloze_format": "The ___ is an abdominal muscle that is not a part of the anterior abdominal wall.", "normal_format": "Which of the following abdominal muscles is not a part of the anterior abdominal wall?", "question_choices": [ "quadratus lumborum", "rectus abdominis", "interior oblique", "exterior oblique" ], "question_id": "fs-id2442596", "question_text": "Which of the following abdominal muscles is not a part of the anterior abdominal wall?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 3, "ans_text": "diaphragm, scalene" }, "bloom": null, "hl_context": "Defecating , urination , and even childbirth involve cooperation between the diaphragm and abdominal muscles ( this cooperation is referred to as the “ Valsalva maneuver ” ) . <hl> You hold your breath by a steady contraction of the diaphragm ; this stabilizes the volume and pressure of the peritoneal cavity . <hl> When the abdominal muscles contract , the pressure cannot push the diaphragm up , so it increases pressure on the intestinal tract ( defecation ) , urinary tract ( urination ) , or reproductive tract ( childbirth ) . Important in the stabilization of the vertebral column is the segmental muscle group , which includes the interspinales and intertransversarii muscles . These muscles bring together the spinous and transverse processes of each consecutive vertebra . <hl> Finally , the scalene muscles work together to flex , laterally flex , and rotate the head . <hl> <hl> They also contribute to deep inhalation . <hl> The scalene muscles include the anterior scalene muscle ( anterior to the middle scalene ) , the middle scalene muscle ( the longest , intermediate between the anterior and posterior scalenes ) , and the posterior scalene muscle ( the smallest , posterior to the middle scalene ) . 11.4 Axial Muscles of the Abdominal Wall , and Thorax Learning Objectives By the end of this section , you will be able to :", "hl_sentences": "You hold your breath by a steady contraction of the diaphragm ; this stabilizes the volume and pressure of the peritoneal cavity . Finally , the scalene muscles work together to flex , laterally flex , and rotate the head . They also contribute to deep inhalation .", "question": { "cloze_format": "___ is the muscle pair that plays a role in respiration.", "normal_format": "Which muscle pair plays a role in respiration?", "question_choices": [ "intertransversarii, interspinales", "semispinalis cervicis, semispinalis thoracis", "trapezius, rhomboids", "diaphragm, scalene" ], "question_id": "fs-id2589732", "question_text": "Which muscle pair plays a role in respiration?" }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 1, "ans_text": "a long tendon that runs down the middle of the rectus abdominis" }, "bloom": "1", "hl_context": "<hl> The linea alba is a white , fibrous band that is made of the bilateral rectus sheaths that join at the anterior midline of the body . <hl> <hl> These enclose the rectus abdominis muscles ( a pair of long , linear muscles , commonly called the “ sit-up ” muscles ) that originate at the pubic crest and symphysis , and extend the length of the body ’ s trunk . <hl> <hl> Each muscle is segmented by three transverse bands of collagen fibers called the tendinous intersections . <hl> This results in the look of “ six-pack abs , ” as each segment hypertrophies on individuals at the gym who do many sit-ups .", "hl_sentences": "The linea alba is a white , fibrous band that is made of the bilateral rectus sheaths that join at the anterior midline of the body . These enclose the rectus abdominis muscles ( a pair of long , linear muscles , commonly called the “ sit-up ” muscles ) that originate at the pubic crest and symphysis , and extend the length of the body ’ s trunk . Each muscle is segmented by three transverse bands of collagen fibers called the tendinous intersections .", "question": { "cloze_format": "The linea alba is ___.", "normal_format": "What is the linea alba?", "question_choices": [ "a small muscle that helps with compression of the abdominal organs", "a long tendon that runs down the middle of the rectus abdominis", "a long band of collagen fibers that connects the hip to the knee", "another name for the tendinous inscription" ], "question_id": "fs-id1383746", "question_text": "What is the linea alba?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 2, "ans_text": "trapezius" }, "bloom": "1", "hl_context": "Muscles that position the pectoral girdle are located either on the anterior thorax or on the posterior thorax ( Figure 11.22 and Table 11.8 ) . The anterior muscles include the subclavius , pectoralis minor , and serratus anterior . <hl> The posterior muscles include the trapezius , rhomboid major , and rhomboid minor . <hl> When the rhomboids are contracted , your scapula moves medially , which can pull the shoulder and upper limb posteriorly . Muscles that Position the Pectoral Girdle", "hl_sentences": "The posterior muscles include the trapezius , rhomboid major , and rhomboid minor .", "question": { "cloze_format": "The rhomboid major and minor muscles are deep to the ________.", "normal_format": "What are the rhomboid major and minor muscles deep into?", "question_choices": [ "rectus abdominis", "scalene muscles", "trapezius", "ligamentum nuchae" ], "question_id": "fs-id2123552", "question_text": "The rhomboid major and minor muscles are deep to the ________." }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 1, "ans_text": "triceps brachii" }, "bloom": "1", "hl_context": "<hl> The biceps brachii flexes the forearm , whereas the triceps brachii extends it . <hl>", "hl_sentences": "The biceps brachii flexes the forearm , whereas the triceps brachii extends it .", "question": { "cloze_format": "The ___ is the muscle that extends the forearm.", "normal_format": "Which muscle extends the forearm?", "question_choices": [ "biceps brachii", "triceps brachii", "brachialis", "deltoid" ], "question_id": "fs-id2044616", "question_text": "Which muscle extends the forearm?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 0, "ans_text": "axial and scapular" }, "bloom": "1", "hl_context": "<hl> Similar to the muscles that position the pectoral girdle , muscles that cross the shoulder joint and move the humerus bone of the arm include both axial and scapular muscles ( Figure 11.23 and Figure 11.24 ) . <hl> The two axial muscles are the pectoralis major and the latissimus dorsi . The pectoralis major is thick and fan-shaped , covering much of the superior portion of the anterior thorax . The broad , triangular latissimus dorsi is located on the inferior part of the back , where it inserts into a thick connective tissue shealth called an aponeurosis . The rest of the shoulder muscles originate on the scapula . The anatomical and ligamental structure of the shoulder joint and the arrangements of the muscles covering it , allows the arm to carry out different types of movements . The deltoid , the thick muscle that creates the rounded lines of the shoulder is the major abductor of the arm , but it also facilitates flexing and medial rotation , as well as extension and lateral rotation . The subscapularis originates on the anterior scapula and medially rotates the arm . Named for their locations , the supraspinatus ( superior to the spine of the scapula ) and the infraspinatus ( inferior to the spine of the scapula ) abduct the arm , and laterally rotate the arm , respectively . The thick and flat teres major is inferior to the teres minor and extends the arm , and assists in adduction and medial rotation of it . The long teres minor laterally rotates and extends the arm . Finally , the coracobrachialis flexes and adducts the arm . The tendons of the deep subscapularis , supraspinatus , infraspinatus , and teres minor connect the scapula to the humerus , forming the rotator cuff ( musculotendinous cuff ) , the circle of tendons around the shoulder joint . When baseball pitchers undergo shoulder surgery it is usually on the rotator cuff , which becomes pinched and inflamed , and may tear away from the bone due to the repetitive motion of bring the arm overhead to throw a fast pitch .", "hl_sentences": "Similar to the muscles that position the pectoral girdle , muscles that cross the shoulder joint and move the humerus bone of the arm include both axial and scapular muscles ( Figure 11.23 and Figure 11.24 ) .", "question": { "cloze_format": "The muscles that stabilize the pectoral girdle are the ___.", "normal_format": "Which muscles stabilize the pectoral girdle?", "question_choices": [ "axial and scapular", "axial", "appendicular", "axial and appendicular" ], "question_id": "fs-id1850372", "question_text": "Which muscles stabilize the pectoral girdle?" }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 0, "ans_text": "gluteal" }, "bloom": null, "hl_context": "<hl> Most muscles that insert on the femur ( the thigh bone ) and move it , originate on the pelvic girdle . <hl> The psoas major and iliacus make up the iliopsoas group . <hl> Some of the largest and most powerful muscles in the body are the gluteal muscles or gluteal group . <hl> <hl> The gluteus maximus is the largest ; deep to the gluteus maximus is the gluteus medius , and deep to the gluteus medius is the gluteus minimus , the smallest of the trio ( Figure 11.29 and Figure 11.30 ) . <hl> The tensor fascia latae is a thick , squarish muscle in the superior aspect of the lateral thigh . It acts as a synergist of the gluteus medius and iliopsoas in flexing and abducting the thigh . It also helps stabilize the lateral aspect of the knee by pulling on the iliotibial tract ( band ) , making it taut . <hl> Deep to the gluteus maximus , the piriformis , obturator internus , obturator externus , superior gemellus , inferior gemellus , and quadratus femoris laterally rotate the femur at the hip . <hl> The adductor longus , adductor brevis , and adductor magnus can both medially and laterally rotate the thigh depending on the placement of the foot . The adductor longus flexes the thigh , whereas the adductor magnus extends it . The pectineus adducts and flexes the femur at the hip as well . The pectineus is located in the femoral triangle , which is formed at the junction between the hip and the leg and also includes the femoral nerve , the femoral artery , the femoral vein , and the deep inguinal lymph nodes .", "hl_sentences": "Most muscles that insert on the femur ( the thigh bone ) and move it , originate on the pelvic girdle . Some of the largest and most powerful muscles in the body are the gluteal muscles or gluteal group . The gluteus maximus is the largest ; deep to the gluteus maximus is the gluteus medius , and deep to the gluteus medius is the gluteus minimus , the smallest of the trio ( Figure 11.29 and Figure 11.30 ) . Deep to the gluteus maximus , the piriformis , obturator internus , obturator externus , superior gemellus , inferior gemellus , and quadratus femoris laterally rotate the femur at the hip .", "question": { "cloze_format": "The large muscle group that attaches the leg to the pelvic girdle and produces extension of the hip joint is the ________ group.", "normal_format": "Which large muscle group attaches the leg to the pelvic girdle and produces extension of the hip joint?", "question_choices": [ "gluteal", "obturator", "adductor", "abductor" ], "question_id": "fs-id2259971", "question_text": "The large muscle group that attaches the leg to the pelvic girdle and produces extension of the hip joint is the ________ group." }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 3, "ans_text": "the sartorius" }, "bloom": "1", "hl_context": "Deep fascia in the thigh separates it into medial , anterior , and posterior compartments ( see Figure 11.29 and Figure 11.31 ) . The muscles in the medial compartment of the thigh are responsible for adducting the femur at the hip . Along with the adductor longus , adductor brevis , adductor magnus , and pectineus , the strap-like gracilis adducts the thigh in addition to flexing the leg at the knee . The muscles of the anterior compartment of the thigh flex the thigh and extend the leg . This compartment contains the quadriceps femoris group , which actually comprises four muscles that extend and stabilize the knee . The rectus femoris is on the anterior aspect of the thigh , the vastus lateralis is on the lateral aspect of the thigh , the vastus medialis is on the medial aspect of the thigh , and the vastus intermedius is between the vastus lateralis and vastus medialis and deep to the rectus femoris . The tendon common to all four is the quadriceps tendon ( patellar tendon ) , which inserts into the patella and continues below it as the patellar ligament . The patellar ligament attaches to the tibial tuberosity . <hl> In addition to the quadriceps femoris , the sartorius is a band-like muscle that extends from the anterior superior iliac spine to the medial side of the proximal tibia . <hl> <hl> This versatile muscle flexes the leg at the knee and flexes , abducts , and laterally rotates the leg at the hip . <hl> <hl> This muscle allows us to sit cross-legged . <hl> The posterior compartment of the thigh includes muscles that flex the leg and extend the thigh . The three long muscles on the back of the knee are the hamstring group , which flexes the knee . These are the biceps femoris , semitendinosus , and semimembranosus . The tendons of these muscles form the popliteal fossa , the diamond-shaped space at the back of the knee .", "hl_sentences": "In addition to the quadriceps femoris , the sartorius is a band-like muscle that extends from the anterior superior iliac spine to the medial side of the proximal tibia . This versatile muscle flexes the leg at the knee and flexes , abducts , and laterally rotates the leg at the hip . This muscle allows us to sit cross-legged .", "question": { "cloze_format": "The muscle that produces movement that allows you to cross your legs is ___.", "normal_format": "Which muscle produces movement that allows you to cross your legs?", "question_choices": [ "the gluteus maximus", "the piriformis", "the gracilis", "the sartorius" ], "question_id": "fs-id2402520", "question_text": "Which muscle produces movement that allows you to cross your legs?" }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 1, "ans_text": "gastrocnemius" }, "bloom": "1", "hl_context": "The lateral compartment of the leg includes two muscles : the fibularis longus ( peroneus longus ) and the fibularis brevis ( peroneus brevis ) . The superficial muscles in the posterior compartment of the leg all insert onto the calcaneal tendon ( Achilles tendon ) , a strong tendon that inserts into the calcaneal bone of the ankle . <hl> The muscles in this compartment are large and strong and keep humans upright . <hl> <hl> The most superficial and visible muscle of the calf is the gastrocnemius . <hl> Deep to the gastrocnemius is the wide , flat soleus . The plantaris runs obliquely between the two ; some people may have two of these muscles , whereas no plantaris is observed in about seven percent of other cadaver dissections . The plantaris tendon is a desirable substitute for the fascia lata in hernia repair , tendon transplants , and repair of ligaments . There are four deep muscles in the posterior compartment of the leg as well : the popliteus , flexor digitorum longus , flexor hallucis longus , and tibialis posterior .", "hl_sentences": "The muscles in this compartment are large and strong and keep humans upright . The most superficial and visible muscle of the calf is the gastrocnemius .", "question": { "cloze_format": "The largest muscle in the lower leg is the ___.", "normal_format": "What is the largest muscle in the lower leg?", "question_choices": [ "soleus", "gastrocnemius", "tibialis anterior", "tibialis posterior" ], "question_id": "fs-id1469672", "question_text": "What is the largest muscle in the lower leg?" }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 1, "ans_text": "rectus femoris" }, "bloom": null, "hl_context": "Deep fascia in the thigh separates it into medial , anterior , and posterior compartments ( see Figure 11.29 and Figure 11.31 ) . The muscles in the medial compartment of the thigh are responsible for adducting the femur at the hip . Along with the adductor longus , adductor brevis , adductor magnus , and pectineus , the strap-like gracilis adducts the thigh in addition to flexing the leg at the knee . The muscles of the anterior compartment of the thigh flex the thigh and extend the leg . This compartment contains the quadriceps femoris group , which actually comprises four muscles that extend and stabilize the knee . <hl> The rectus femoris is on the anterior aspect of the thigh , the vastus lateralis is on the lateral aspect of the thigh , the vastus medialis is on the medial aspect of the thigh , and the vastus intermedius is between the vastus lateralis and vastus medialis and deep to the rectus femoris . <hl> The tendon common to all four is the quadriceps tendon ( patellar tendon ) , which inserts into the patella and continues below it as the patellar ligament . The patellar ligament attaches to the tibial tuberosity . In addition to the quadriceps femoris , the sartorius is a band-like muscle that extends from the anterior superior iliac spine to the medial side of the proximal tibia . This versatile muscle flexes the leg at the knee and flexes , abducts , and laterally rotates the leg at the hip . This muscle allows us to sit cross-legged . The posterior compartment of the thigh includes muscles that flex the leg and extend the thigh . The three long muscles on the back of the knee are the hamstring group , which flexes the knee . These are the biceps femoris , semitendinosus , and semimembranosus . The tendons of these muscles form the popliteal fossa , the diamond-shaped space at the back of the knee .", "hl_sentences": "The rectus femoris is on the anterior aspect of the thigh , the vastus lateralis is on the lateral aspect of the thigh , the vastus medialis is on the medial aspect of the thigh , and the vastus intermedius is between the vastus lateralis and vastus medialis and deep to the rectus femoris .", "question": { "cloze_format": "The muscles that the vastus intermedius muscle is deep to is the ___.", "normal_format": "The vastus intermedius muscle is deep to which of the following muscles?", "question_choices": [ "biceps femoris", "rectus femoris", "vastus medialis", "vastus lateralis" ], "question_id": "fs-id2754614", "question_text": "The vastus intermedius muscle is deep to which of the following muscles?" }, "references_are_paraphrase": 0 } ]
11
11.1 Interactions of Skeletal Muscles, Their Fascicle Arrangement, and Their Lever Systems Learning Objectives By the end of this section, you will be able to: Compare and contrast agonist and antagonist muscles Describe how fascicles are arranged within a skeletal muscle Explain the major events of a skeletal muscle contraction within a muscle in generating force To move the skeleton, the tension created by the contraction of the fibers in most skeletal muscles is transferred to the tendons. The tendons are strong bands of dense, regular connective tissue that connect muscles to bones. The bone connection is why this muscle tissue is called skeletal muscle. Interactions of Skeletal Muscles in the Body To pull on a bone, that is, to change the angle at its synovial joint, which essentially moves the skeleton, a skeletal muscle must also be attached to a fixed part of the skeleton. The moveable end of the muscle that attaches to the bone being pulled is called the muscle’s insertion , and the end of the muscle attached to a fixed (stabilized) bone is called the origin . During forearm flexion —bending the elbow—the brachioradialis assists the brachialis. Although a number of muscles may be involved in an action, the principal muscle involved is called the prime mover , or agonist . To lift a cup, a muscle called the biceps brachii is actually the prime mover; however, because it can be assisted by the brachialis, the brachialis is called a synergist in this action ( Figure 11.2 ). A synergist can also be a fixator that stabilizes the bone that is the attachment for the prime mover’s origin. A muscle with the opposite action of the prime mover is called an antagonist . Antagonists play two important roles in muscle function: (1) they maintain body or limb position, such as holding the arm out or standing erect; and (2) they control rapid movement, as in shadow boxing without landing a punch or the ability to check the motion of a limb. For example, to extend the knee, a group of four muscles called the quadriceps femoris in the anterior compartment of the thigh are activated (and would be called the agonists of knee extension). However, to flex the knee joint, an opposite or antagonistic set of muscles called the hamstrings is activated. As you can see, these terms would also be reversed for the opposing action. If you consider the first action as the knee bending, the hamstrings would be called the agonists and the quadriceps femoris would then be called the antagonists. See Table 11.1 for a list of some agonists and antagonists. Agonist and Antagonist Skeletal Muscle Pairs Agonist Antagonist Movement Biceps brachii: in the anterior compartment of the arm Triceps brachii: in the posterior compartment of the arm The biceps brachii flexes the forearm, whereas the triceps brachii extends it. Hamstrings: group of three muscles in the posterior compartment of the thigh Quadriceps femoris: group of four muscles in the anterior compartment of the thigh The hamstrings flex the leg, whereas the quadriceps femoris extend it. Flexor digitorum superficialis and flexor digitorum profundus: in the anterior compartment of the forearm Extensor digitorum: in the posterior compartment of the forearm The flexor digitorum superficialis and flexor digitorum profundus flex the fingers and the hand at the wrist, whereas the extensor digitorum extends the fingers and the hand at the wrist. Table 11.1 There are also skeletal muscles that do not pull against the skeleton for movements. For example, there are the muscles that produce facial expressions. The insertions and origins of facial muscles are in the skin, so that certain individual muscles contract to form a smile or frown, form sounds or words, and raise the eyebrows. There also are skeletal muscles in the tongue, and the external urinary and anal sphincters that allow for voluntary regulation of urination and defecation, respectively. In addition, the diaphragm contracts and relaxes to change the volume of the pleural cavities but it does not move the skeleton to do this. Everyday Connection Exercise and Stretching When exercising, it is important to first warm up the muscles. Stretching pulls on the muscle fibers and it also results in an increased blood flow to the muscles being worked. Without a proper warm-up, it is possible that you may either damage some of the muscle fibers or pull a tendon. A pulled tendon, regardless of location, results in pain, swelling, and diminished function; if it is moderate to severe, the injury could immobilize you for an extended period. Recall the discussion about muscles crossing joints to create movement. Most of the joints you use during exercise are synovial joints, which have synovial fluid in the joint space between two bones. Exercise and stretching may also have a beneficial effect on synovial joints. Synovial fluid is a thin, but viscous film with the consistency of egg whites. When you first get up and start moving, your joints feel stiff for a number of reasons. After proper stretching and warm-up, the synovial fluid may become less viscous, allowing for better joint function. Patterns of Fascicle Organization Skeletal muscle is enclosed in connective tissue scaffolding at three levels. Each muscle fiber (cell) is covered by endomysium and the entire muscle is covered by epimysium. When a group of muscle fibers is “bundled” as a unit within the whole muscle by an additional covering of a connective tissue called perimysium, that bundled group of muscle fibers is called a fascicle . Fascicle arrangement by perimysia is correlated to the force generated by a muscle; it also affects the range of motion of the muscle. Based on the patterns of fascicle arrangement, skeletal muscles can be classified in several ways. What follows are the most common fascicle arrangements. Parallel muscles have fascicles that are arranged in the same direction as the long axis of the muscle ( Figure 11.3 ). The majority of skeletal muscles in the body have this type of organization. Some parallel muscles are flat sheets that expand at the ends to make broad attachments. Other parallel muscles are rotund with tendons at one or both ends. Muscles that seem to be plump have a large mass of tissue located in the middle of the muscle, between the insertion and the origin, which is known as the central body. A more common name for this muscle is belly . When a muscle contracts, the contractile fibers shorten it to an even larger bulge. For example, extend and then flex your biceps brachii muscle; the large, middle section is the belly ( Figure 11.4 ). When a parallel muscle has a central, large belly that is spindle-shaped, meaning it tapers as it extends to its origin and insertion, it sometimes is called fusiform . Circular muscles are also called sphincters (see Figure 11.3 ). When they relax, the sphincters’ concentrically arranged bundles of muscle fibers increase the size of the opening, and when they contract, the size of the opening shrinks to the point of closure. The orbicularis oris muscle is a circular muscle that goes around the mouth. When it contracts, the oral opening becomes smaller, as when puckering the lips for whistling. Another example is the orbicularis oculi, one of which surrounds each eye. Consider, for example, the names of the two orbicularis muscles (orbicularis oris and oribicularis oculi), where part of the first name of both muscles is the same. The first part of orbicularis, orb (orb = “circular”), is a reference to a round or circular structure; it may also make one think of orbit, such as the moon’s path around the earth. The word oris (oris = “oral”) refers to the oral cavity, or the mouth. The word oculi (ocular = “eye”) refers to the eye. There are other muscles throughout the body named by their shape or location. The deltoid is a large, triangular-shaped muscle that covers the shoulder. It is so-named because the Greek letter delta looks like a triangle. The rectus abdominis (rector = “straight”) is the straight muscle in the anterior wall of the abdomen, while the rectus femoris is the straight muscle in the anterior compartment of the thigh. When a muscle has a widespread expansion over a sizable area, but then the fascicles come to a single, common attachment point, the muscle is called convergent . The attachment point for a convergent muscle could be a tendon, an aponeurosis (a flat, broad tendon), or a raphe (a very slender tendon). The large muscle on the chest, the pectoralis major, is an example of a convergent muscle because it converges on the greater tubercle of the humerus via a tendon. The temporalis muscle of the cranium is another. Pennate muscles (penna = “feathers”) blend into a tendon that runs through the central region of the muscle for its whole length, somewhat like the quill of a feather with the muscle arranged similar to the feathers. Due to this design, the muscle fibers in a pennate muscle can only pull at an angle, and as a result, contracting pennate muscles do not move their tendons very far. However, because a pennate muscle generally can hold more muscle fibers within it, it can produce relatively more tension for its size. There are three subtypes of pennate muscles. In a unipennate muscle, the fascicles are located on one side of the tendon. The extensor digitorum of the forearm is an example of a unipennate muscle. A bipennate muscle has fascicles on both sides of the tendon. In some pennate muscles, the muscle fibers wrap around the tendon, sometimes forming individual fascicles in the process. This arrangement is referred to as multipennate . A common example is the deltoid muscle of the shoulder, which covers the shoulder but has a single tendon that inserts on the deltoid tuberosity of the humerus. Because of fascicles, a portion of a multipennate muscle like the deltoid can be stimulated by the nervous system to change the direction of the pull. For example, when the deltoid muscle contracts, the arm abducts (moves away from midline in the sagittal plane), but when only the anterior fascicle is stimulated, the arm will abduct and flex (move anteriorly at the shoulder joint). The Lever System of Muscle and Bone Interactions Skeletal muscles do not work by themselves. Muscles are arranged in pairs based on their functions. For muscles attached to the bones of the skeleton, the connection determines the force, speed, and range of movement. These characteristics depend on each other and can explain the general organization of the muscular and skeletal systems. The skeleton and muscles act together to move the body. Have you ever used the back of a hammer to remove a nail from wood? The handle acts as a lever and the head of the hammer acts as a fulcrum, the fixed point that the force is applied to when you pull back or push down on the handle. The effort applied to this system is the pulling or pushing on the handle to remove the nail, which is the load, or “resistance” to the movement of the handle in the system. Our musculoskeletal system works in a similar manner, with bones being stiff levers and the articular endings of the bones—encased in synovial joints—acting as fulcrums. The load would be an object being lifted or any resistance to a movement (your head is a load when you are lifting it), and the effort, or applied force, comes from contracting skeletal muscle. 11.2 Naming Skeletal Muscles Learning Objectives By the end of this section, you will be able to: Describe the criteria used to name skeletal muscles Explain how understanding the muscle names helps describe shapes, location, and actions of various muscles The Greeks and Romans conducted the first studies done on the human body in Western culture. The educated class of subsequent societies studied Latin and Greek, and therefore the early pioneers of anatomy continued to apply Latin and Greek terminology or roots when they named the skeletal muscles. The large number of muscles in the body and unfamiliar words can make learning the names of the muscles in the body seem daunting, but understanding the etymology can help. Etymology is the study of how the root of a particular word entered a language and how the use of the word evolved over time. Taking the time to learn the root of the words is crucial to understanding the vocabulary of anatomy and physiology. When you understand the names of muscles it will help you remember where the muscles are located and what they do ( Figure 11.5 , Figure 11.6 , and Table 11.2 ). Pronunciation of words and terms will take a bit of time to master, but after you have some basic information; the correct names and pronunciations will become easier. Mnemonic Device for Latin Roots Example Latin or Greek Translation Mnemonic Device ad to; toward ADvance toward your goal ab away from n/a sub under SUBmarines move under water. ductor something that moves A conDUCTOR makes a train move. anti against If you are antisocial, you are against engaging in social activities. epi on top of n/a apo to the side of n/a longissimus longest “Longissimus” is longer than the word “long.” longus long long brevis short brief maximus large max medius medium “Medius” and “medium” both begin with “med.” minimus tiny; little mini rectus straight To RECTify a situation is to straighten it out. multi many If something is MULTIcolored, it has many colors. uni one A UNIcorn has one horn. bi/di two If a ring is DIcast, it is made of two metals. tri three TRIple the amount of money is three times as much. quad four QUADruplets are four children born at one birth. externus outside EXternal internus inside INternal Table 11.2 Anatomists name the skeletal muscles according to a number of criteria, each of which describes the muscle in some way. These include naming the muscle after its shape, its size compared to other muscles in the area, its location in the body or the location of its attachments to the skeleton, how many origins it has, or its action. The skeletal muscle’s anatomical location or its relationship to a particular bone often determines its name. For example, the frontalis muscle is located on top of the frontal bone of the skull. Similarly, the shapes of some muscles are very distinctive and the names, such as orbicularis, reflect the shape. For the buttocks, the size of the muscles influences the names: gluteus maximus (largest), gluteus medius (medium), and the gluteus minimus (smallest). Names were given to indicate length— brevis (short), longus (long)—and to identify position relative to the midline: lateralis (to the outside away from the midline), and medialis (toward the midline). The direction of the muscle fibers and fascicles are used to describe muscles relative to the midline, such as the rectus (straight) abdominis, or the oblique (at an angle) muscles of the abdomen. Some muscle names indicate the number of muscles in a group. One example of this is the quadriceps, a group of four muscles located on the anterior (front) thigh. Other muscle names can provide information as to how many origins a particular muscle has, such as the biceps brachii. The prefix bi indicates that the muscle has two origins and tri indicates three origins. The location of a muscle’s attachment can also appear in its name. When the name of a muscle is based on the attachments, the origin is always named first. For instance, the sternocleidomastoid muscle of the neck has a dual origin on the sternum (sterno) and clavicle (cleido), and it inserts on the mastoid process of the temporal bone. The last feature by which to name a muscle is its action. When muscles are named for the movement they produce, one can find action words in their name. Some examples are flexor (decreases the angle at the joint), extensor (increases the angle at the joint), abductor (moves the bone away from the midline), or adductor (moves the bone toward the midline). 11.3 Axial Muscles of the Head, Neck, and Back Learning Objectives By the end of this section, you will be able to: Identify the axial muscles of the face, head, and neck Identify the movement and function of the face, head, and neck muscles The skeletal muscles are divided into axial (muscles of the trunk and head) and appendicular (muscles of the arms and legs) categories. This system reflects the bones of the skeleton system, which are also arranged in this manner. The axial muscles are grouped based on location, function, or both. Some of the axial muscles may seem to blur the boundaries because they cross over to the appendicular skeleton. The first grouping of the axial muscles you will review includes the muscles of the head and neck, then you will review the muscles of the vertebral column, and finally you will review the oblique and rectus muscles. Muscles That Create Facial Expression The origins of the muscles of facial expression are on the surface of the skull (remember, the origin of a muscle does not move). The insertions of these muscles have fibers intertwined with connective tissue and the dermis of the skin. Because the muscles insert in the skin rather than on bone, when they contract, the skin moves to create facial expression ( Figure 11.7 ). The orbicularis oris is a circular muscle that moves the lips, and the orbicularis oculi is a circular muscle that closes the eye. The occipitofrontalis muscle moves up the scalp and eyebrows. The muscle has a frontal belly and an occipital (near the occipital bone on the posterior part of the skull) belly. In other words, there is a muscle on the forehead ( frontalis ) and one on the back of the head ( occipitalis ), but there is no muscle across the top of the head. Instead, the two bellies are connected by a broad tendon called the epicranial aponeurosis , or galea aponeurosis (galea = “helmet”). The physicians originally studying human anatomy thought the skull looked like an helmet. A large portion of the face is composed of the buccinator muscle, which compresses the cheek. This muscle allows you to whistle, blow, and suck; and it contributes to the action of chewing. There are several small facial muscles, one of which is the corrugator supercilii , which is the prime mover of the eyebrows. Place your finger on your eyebrows at the point of the bridge of the nose. Raise your eyebrows as if you were surprised and lower your eyebrows as if you were frowning. With these movements, you can feel the action of the corrugator supercilii. Additional muscles of facial expression are presented in Figure 11.8 . Muscles That Move the Eyes The movement of the eyeball is under the control of the extrinsic eye muscles , which originate outside the eye and insert onto the outer surface of the white of the eye. These muscles are located inside the eye socket and cannot be seen on any part of the visible eyeball ( Figure 11.9 and Table 11.3 ). If you have ever been to a doctor who held up a finger and asked you to follow it up, down, and to both sides, he or she is checking to make sure your eye muscles are acting in a coordinated pattern. Muscles of the Eyes Movement Target Target motion direction Prime mover Origin Insertion Moves eyes up and toward nose; rotates eyes from 1 o’clock to 3 o’clock Eyeballs Superior (elevates); medial (adducts) Superior rectus Common tendinous ring (ring attaches to optic foramen) Superior surface of eyeball Moves eyes down and toward nose; rotates eyes from 6 o’clock to 3 o’clock Eyeballs Inferior (depresses); medial (adducts) Inferior rectus Common tendinous ring (ring attaches to optic foramen) Inferior surface of eyeball Moves eyes away from nose Eyeballs Lateral (abducts) Lateral rectus Common tendinous ring (ring attaches to optic foramen) Lateral surface of eyeball Moves eyes toward nose Eyeballs Medial (adducts) Medial rectus Common tendinous ring (ring attaches to optic foramen) Medial surface of eyeball Moves eyes up and away from nose; rotates eyeball from 12 o’clock to 9 o’clock Eyeballs Superior (elevates); lateral (abducts) Inferior oblique Floor of orbit (maxilla) Surface of eyeball between inferior rectus and lateral rectus Moves eyes down and away from nose; rotates eyeball from 6 o’clock to 9 o’clock Eyeballs Inferior (depress); lateral (abducts) Superior oblique Sphenoid bone Surface of eyeball between superior rectus and lateral rectus Opens eyes Upper eyelid Superior (elevates) Levator palpabrae superioris Roof of orbit (sphenoid bone) Skin of upper eyelids Closes eyelids Eyelid skin Compression along superior–inferior axis Orbicularis oculi Medial bones composing the orbit Circumference of orbit Table 11.3 Muscles That Move the Lower Jaw In anatomical terminology, chewing is called mastication . Muscles involved in chewing must be able to exert enough pressure to bite through and then chew food before it is swallowed ( Figure 11.10 and Table 11.4 ). The masseter muscle is the main muscle used for chewing because it elevates the mandible (lower jaw) to close the mouth, and it is assisted by the temporalis muscle, which retracts the mandible. You can feel the temporalis move by putting your fingers to your temple as you chew. Muscles of the Lower Jaw Movement Target Target motion direction Prime mover Origin Insertion Closes mouth; aids chewing Mandible Superior (elevates) Masseter Maxilla arch; zygomatic arch (for masseter) Mandible Closes mouth; pulls lower jaw in under upper jaw Mandible Superior (elevates); posterior (retracts) Temporalis Temporal bone Mandible Opens mouth; pushes lower jaw out under upper jaw; moves lower jaw side-to-side Mandible Inferior (depresses); posterior (protracts); lateral (abducts); medial (adducts) Lateral pterygoid Pterygoid process of sphenoid bone Mandible Closes mouth; pushes lower jaw out under upper jaw; moves lower jaw side-to-side Mandible Superior (elevates); posterior (protracts); lateral (abducts); medial (adducts) Medial pterygoid Sphenoid bone; maxilla Mandible; temporo-mandibular joint Table 11.4 Although the masseter and temporalis are responsible for elevating and closing the jaw to break food into digestible pieces, the medial pterygoid and lateral pterygoid muscles provide assistance in chewing and moving food within the mouth. Muscles That Move the Tongue Although the tongue is obviously important for tasting food, it is also necessary for mastication, deglutition (swallowing), and speech ( Figure 11.11 and Figure 11.12 ). Because it is so moveable, the tongue facilitates complex speech patterns and sounds. Tongue muscles can be extrinsic or intrinsic. Extrinsic tongue muscles insert into the tongue from outside origins, and the intrinsic tongue muscles insert into the tongue from origins within it. The extrinsic muscles move the whole tongue in different directions, whereas the intrinsic muscles allow the tongue to change its shape (such as, curling the tongue in a loop or flattening it). The extrinsic muscles all include the word root glossus (glossus = “tongue”), and the muscle names are derived from where the muscle originates. The genioglossus (genio = “chin”) originates on the mandible and allows the tongue to move downward and forward. The styloglossus originates on the styloid bone, and allows upward and backward motion. The palatoglossus originates on the soft palate to elevate the back of the tongue, and the hyoglossus originates on the hyoid bone to move the tongue downward and flatten it. Everyday Connection Anesthesia and the Tongue Muscles Before surgery, a patient must be made ready for general anesthesia. The normal homeostatic controls of the body are put “on hold” so that the patient can be prepped for surgery. Control of respiration must be switched from the patient’s homeostatic control to the control of the anesthesiologist. The drugs used for anesthesia relax a majority of the body’s muscles. Among the muscles affected during general anesthesia are those that are necessary for breathing and moving the tongue. Under anesthesia, the tongue can relax and partially or fully block the airway, and the muscles of respiration may not move the diaphragm or chest wall. To avoid possible complications, the safest procedure to use on a patient is called endotracheal intubation. Placing a tube into the trachea allows the doctors to maintain a patient’s (open) airway to the lungs and seal the airway off from the oropharynx. Post-surgery, the anesthesiologist gradually changes the mixture of the gases that keep the patient unconscious, and when the muscles of respiration begin to function, the tube is removed. It still takes about 30 minutes for a patient to wake up, and for breathing muscles to regain control of respiration. After surgery, most people have a sore or scratchy throat for a few days. Muscles of the Anterior Neck The muscles of the anterior neck assist in deglutition (swallowing) and speech by controlling the positions of the larynx (voice box), and the hyoid bone, a horseshoe-shaped bone that functions as a solid foundation on which the tongue can move. The muscles of the neck are categorized according to their position relative to the hyoid bone ( Figure 11.13 ). Suprahyoid muscles are superior to it, and the infrahyoid muscles are located inferiorly. The suprahyoid muscles raise the hyoid bone, the floor of the mouth, and the larynx during deglutition. These include the digastric muscle, which has anterior and posterior bellies that work to elevate the hyoid bone and larynx when one swallows; it also depresses the mandible. The stylohyoid muscle moves the hyoid bone posteriorly, elevating the larynx, and the mylohyoid muscle lifts it and helps press the tongue to the top of the mouth. The geniohyoid depresses the mandible in addition to raising and pulling the hyoid bone anteriorly. The strap-like infrahyoid muscles generally depress the hyoid bone and control the position of the larynx. The omohyoid muscle, which has superior and inferior bellies, depresses the hyoid bone in conjunction with the sternohyoid and thyrohyoid muscles. The thyrohyoid muscle also elevates the larynx’s thyroid cartilage, whereas the sternothyroid depresses it to create different tones of voice. Muscles That Move the Head The head, attached to the top of the vertebral column, is balanced, moved, and rotated by the neck muscles ( Table 11.5 ). When these muscles act unilaterally, the head rotates. When they contract bilaterally, the head flexes or extends. The major muscle that laterally flexes and rotates the head is the sternocleidomastoid . In addition, both muscles working together are the flexors of the head. Place your fingers on both sides of the neck and turn your head to the left and to the right. You will feel the movement originate there. This muscle divides the neck into anterior and posterior triangles when viewed from the side ( Figure 11.14 ). Muscles That Move the Head Movement Target Target motion direction Prime mover Origin Insertion Rotates and tilts head to the side; tilts head forward Skull; vertebrae Individually: rotates head to opposite side; bilaterally: flexion Sternocleidomastoid Sternum; clavicle Temporal bone (mastoid process); occipital bone Rotates and tilts head backward Skull; vertebrae Individually: laterally flexes and rotates head to same side; bilaterally: extension Semispinalis capitis Transverse and articular processes of cervical and thoracic vertebra Occipital bone Rotates and tilts head to the side; tilts head backward Skull; vertebrae Individually: laterally flexes and rotates head to same side; bilaterally: extension Splenius capitis Spinous processes of cervical and thoracic vertebra Temporal bone (mastoid process); occipital bone Rotates and tilts head to the side; tilts head backward Skull; vertebrae Individually: laterally flexes and rotates head to same side; bilaterally: extension Longissimus capitis Transverse and articular processes of cervical and thoracic vertebra Temporal bone (mastoid process) Table 11.5 Muscles of the Posterior Neck and the Back The posterior muscles of the neck are primarily concerned with head movements, like extension. The back muscles stabilize and move the vertebral column, and are grouped according to the lengths and direction of the fascicles. The splenius muscles originate at the midline and run laterally and superiorly to their insertions. From the sides and the back of the neck, the splenius capitis inserts onto the head region, and the splenius cervicis extends onto the cervical region. These muscles can extend the head, laterally flex it, and rotate it ( Figure 11.15 ). The erector spinae group forms the majority of the muscle mass of the back and it is the primary extensor of the vertebral column. It controls flexion, lateral flexion, and rotation of the vertebral column, and maintains the lumbar curve. The erector spinae comprises the iliocostalis (laterally placed) group, the longissimus (intermediately placed) group, and the spinalis (medially placed) group. The iliocostalis group includes the iliocostalis cervicis , associated with the cervical region; the iliocostalis thoracis , associated with the thoracic region; and the iliocostalis lumborum , associated with the lumbar region. The three muscles of the longissimus group are the longissimus capitis , associated with the head region; the longissimus cervicis , associated with the cervical region; and the longissimus thoracis , associated with the thoracic region. The third group, the spinalis group , comprises the spinalis capitis (head region), the spinalis cervicis (cervical region), and the spinalis thoracis (thoracic region). The transversospinales muscles run from the transverse processes to the spinous processes of the vertebrae. Similar to the erector spinae muscles, the semispinalis muscles in this group are named for the areas of the body with which they are associated. The semispinalis muscles include the semispinalis capitis , the semispinalis cervicis , and the semispinalis thoracis . The multifidus muscle of the lumbar region helps extend and laterally flex the vertebral column. Important in the stabilization of the vertebral column is the segmental muscle group , which includes the interspinales and intertransversarii muscles. These muscles bring together the spinous and transverse processes of each consecutive vertebra. Finally, the scalene muscles work together to flex, laterally flex, and rotate the head. They also contribute to deep inhalation. The scalene muscles include the anterior scalene muscle (anterior to the middle scalene), the middle scalene muscle (the longest, intermediate between the anterior and posterior scalenes), and the posterior scalene muscle (the smallest, posterior to the middle scalene). 11.4 Axial Muscles of the Abdominal Wall, and Thorax Learning Objectives By the end of this section, you will be able to: Identify the intrinsic skeletal muscles of the back and neck, and the skeletal muscles of the abdominal wall and thorax Identify the movement and function of the intrinsic skeletal muscles of the back and neck, and the skeletal muscles of the abdominal wall and thorax It is a complex job to balance the body on two feet and walk upright. The muscles of the vertebral column, thorax, and abdominal wall extend, flex, and stabilize different parts of the body’s trunk. The deep muscles of the core of the body help maintain posture as well as carry out other functions. The brain sends out electrical impulses to these various muscle groups to control posture by alternate contraction and relaxation. This is necessary so that no single muscle group becomes fatigued too quickly. If any one group fails to function, body posture will be compromised. Muscles of the Abdomen There are four pairs of abdominal muscles that cover the anterior and lateral abdominal region and meet at the anterior midline. These muscles of the anterolateral abdominal wall can be divided into four groups: the external obliques, the internal obliques, the transversus abdominis, and the rectus abdominis ( Figure 11.16 and Table 11.6 ). Muscles of the Abdomen Movement Target Target motion direction Prime mover Origin Insertion Twisting at waist; also bending to the side Vertebral column Supination; lateral flexion External obliques; internal obliques Ribs 5–12; ilium Ribs 7–10; linea alba; ilium Squeezing abdomen during forceful exhalations, defecation, urination, and childbirth Abdominal cavity Compression Transversus abdominis Ilium; ribs 5–10 Sternum; linea alba; pubis Sitting up Vertebral column Flexion Rectus abdominis Pubis Sternum; ribs 5 and 7 Bending to the side Vertebral column Lateral flexion Quadratus lumborum Ilium; ribs 5–10 Rib 12; vertebrae L1–L4 Table 11.6 There are three flat skeletal muscles in the antero-lateral wall of the abdomen. The external oblique , closest to the surface, extend inferiorly and medially, in the direction of sliding one’s four fingers into pants pockets. Perpendicular to it is the intermediate internal oblique , extending superiorly and medially, the direction the thumbs usually go when the other fingers are in the pants pocket. The deep muscle, the transversus abdominis , is arranged transversely around the abdomen, similar to the front of a belt on a pair of pants. This arrangement of three bands of muscles in different orientations allows various movements and rotations of the trunk. The three layers of muscle also help to protect the internal abdominal organs in an area where there is no bone. The linea alba is a white, fibrous band that is made of the bilateral rectus sheaths that join at the anterior midline of the body. These enclose the rectus abdominis muscles (a pair of long, linear muscles, commonly called the “sit-up” muscles) that originate at the pubic crest and symphysis, and extend the length of the body’s trunk. Each muscle is segmented by three transverse bands of collagen fibers called the tendinous intersections . This results in the look of “six-pack abs,” as each segment hypertrophies on individuals at the gym who do many sit-ups. The posterior abdominal wall is formed by the lumbar vertebrae, parts of the ilia of the hip bones, psoas major and iliacus muscles, and quadratus lumborum muscle. This part of the core plays a key role in stabilizing the rest of the body and maintaining posture. Career Connection Physical Therapists Those who have a muscle or joint injury will most likely be sent to a physical therapist (PT) after seeing their regular doctor. PTs have a master’s degree or doctorate, and are highly trained experts in the mechanics of body movements. Many PTs also specialize in sports injuries. If you injured your shoulder while you were kayaking, the first thing a physical therapist would do during your first visit is to assess the functionality of the joint. The range of motion of a particular joint refers to the normal movements the joint performs. The PT will ask you to abduct and adduct, circumduct, and flex and extend the arm. The PT will note the shoulder’s degree of function, and based on the assessment of the injury, will create an appropriate physical therapy plan. The first step in physical therapy will probably be applying a heat pack to the injured site, which acts much like a warm-up to draw blood to the area, to enhance healing. You will be instructed to do a series of exercises to continue the therapy at home, followed by icing, to decrease inflammation and swelling, which will continue for several weeks. When physical therapy is complete, the PT will do an exit exam and send a detailed report on the improved range of motion and return of normal limb function to your doctor. Gradually, as the injury heals, the shoulder will begin to function correctly. A PT works closely with patients to help them get back to their normal level of physical activity. Muscles of the Thorax The muscles of the chest serve to facilitate breathing by changing the size of the thoracic cavity ( Table 11.7 ). When you inhale, your chest rises because the cavity expands. Alternately, when you exhale, your chest falls because the thoracic cavity decreases in size. Muscles of the Thorax Movement Target Target motion direction Prime mover Origin Insertion Inhalation; exhalation Thoracic cavity Compression; expansion Diaphragm Sternum; ribs 6–12; lumbar vertebrae Central tendon Inhalation;exhalation Ribs Elevation (expands thoracic cavity) External intercostals Rib superior to each intercostal muscle Rib inferior to each intercostal muscle Forced exhalation Ribs Movement along superior/inferior axis to bring ribs closer together Internal intercostals Rib inferior to each intercostal muscle Rib superior to each intercostal muscle Table 11.7 The Diaphragm The change in volume of the thoracic cavity during breathing is due to the alternate contraction and relaxation of the diaphragm ( Figure 11.17 ). It separates the thoracic and abdominal cavities, and is dome-shaped at rest. The superior surface of the diaphragm is convex, creating the elevated floor of the thoracic cavity. The inferior surface is concave, creating the curved roof of the abdominal cavity. Defecating, urination, and even childbirth involve cooperation between the diaphragm and abdominal muscles (this cooperation is referred to as the “Valsalva maneuver”). You hold your breath by a steady contraction of the diaphragm; this stabilizes the volume and pressure of the peritoneal cavity. When the abdominal muscles contract, the pressure cannot push the diaphragm up, so it increases pressure on the intestinal tract (defecation), urinary tract (urination), or reproductive tract (childbirth). The inferior surface of the pericardial sac and the inferior surfaces of the pleural membranes (parietal pleura) fuse onto the central tendon of the diaphragm. To the sides of the tendon are the skeletal muscle portions of the diaphragm, which insert into the tendon while having a number of origins including the xiphoid process of the sternum anteriorly, the inferior six ribs and their cartilages laterally, and the lumbar vertebrae and 12th ribs posteriorly. The diaphragm also includes three openings for the passage of structures between the thorax and the abdomen. The inferior vena cava passes through the caval opening , and the esophagus and attached nerves pass through the esophageal hiatus. The aorta, thoracic duct, and azygous vein pass through the aortic hiatus of the posterior diaphragm. The Intercostal Muscles There are three sets of muscles, called intercostal muscles , which span each of the intercostal spaces. The principal role of the intercostal muscles is to assist in breathing by changing the dimensions of the rib cage ( Figure 11.18 ). The 11 pairs of superficial external intercostal muscles aid in inspiration of air during breathing because when they contract, they raise the rib cage, which expands it. The 11 pairs of internal intercostal muscles, just under the externals, are used for expiration because they draw the ribs together to constrict the rib cage. The innermost intercostal muscles are the deepest, and they act as synergists for the action of the internal intercostals. Muscles of the Pelvic Floor and Perineum The pelvic floor is a muscular sheet that defines the inferior portion of the pelvic cavity. The pelvic diaphragm , spanning anteriorly to posteriorly from the pubis to the coccyx, comprises the levator ani and the ischiococcygeus. Its openings include the anal canal and urethra, and the vagina in women. The large levator ani consists of two skeletal muscles, the pubococcygeus and the iliococcygeus ( Figure 11.19 ). The levator ani is considered the most important muscle of the pelvic floor because it supports the pelvic viscera. It resists the pressure produced by contraction of the abdominal muscles so that the pressure is applied to the colon to aid in defecation and to the uterus to aid in childbirth (assisted by the ischiococcygeus , which pulls the coccyx anteriorly). This muscle also creates skeletal muscle sphincters at the urethra and anus. The perineum is the diamond-shaped space between the pubic symphysis (anteriorly), the coccyx (posteriorly), and the ischial tuberosities (laterally), lying just inferior to the pelvic diaphragm (levator ani and coccygeus). Divided transversely into triangles, the anterior is the urogenital triangle , which includes the external genitals. The posterior is the anal triangle , which contains the anus ( Figure 11.20 ). The perineum is also divided into superficial and deep layers with some of the muscles common to men and women ( Figure 11.21 ). Women also have the compressor urethrae and the sphincter urethrovaginalis , which function to close the vagina. In men, there is the deep transverse perineal muscle that plays a role in ejaculation. 11.5 Muscles of the Pectoral Girdle and Upper Limbs Learning Objectives By the end of this section, you will be able to: Identify the muscles of the pectoral girdle and upper limbs Identify the movement and function of the pectoral girdle and upper limbs Muscles of the shoulder and upper limb can be divided into four groups: muscles that stabilize and position the pectoral girdle, muscles that move the arm, muscles that move the forearm, and muscles that move the wrists, hands, and fingers. The pectoral girdle , or shoulder girdle, consists of the lateral ends of the clavicle and scapula, along with the proximal end of the humerus, and the muscles covering these three bones to stabilize the shoulder joint. The girdle creates a base from which the head of the humerus, in its ball-and-socket joint with the glenoid fossa of the scapula, can move the arm in multiple directions. Muscles That Position the Pectoral Girdle Muscles that position the pectoral girdle are located either on the anterior thorax or on the posterior thorax ( Figure 11.22 and Table 11.8 ). The anterior muscles include the subclavius , pectoralis minor , and serratus anterior . The posterior muscles include the trapezius , rhomboid major , and rhomboid minor . When the rhomboids are contracted, your scapula moves medially, which can pull the shoulder and upper limb posteriorly. Muscles that Position the Pectoral Girdle Position in the thorax Movement Target Target motion direction Prime mover Origin Insertion Anterior thorax Stabilizes clavicle during movement by depressing it Clavicle Depression Subclavius First rib Inferior surface of clavicle Anterior thorax Rotates shoulder anteriorly (throwing motion); assists with inhalation Scapula; ribs Scapula: depresses; ribs: elevates Pectoralis minor Anterior surfaces of certain ribs (2–4 or 3–5) Coracoid process of scapula Anterior thorax Moves arm from side of body to front of body; assists with inhalation Scapula; ribs Scapula: protracts; ribs: elevates Serratus anterior Muscle slips from certain ribs (1–8 or 1–9) Anterior surface of vertebral border of scapula Posterior thorax Elevates shoulders (shrugging); pulls shoulder blades together; tilts head backwards Scapula; cervical spine Scapula: rotests inferiorly, retracts, elevates, and depresses; spine: extends Trapezius Skull; vertebral column Acromion and spine of scapula; clavicle Posterior thorax Stabilizes scapula during pectoral girdle movement Scapula Retracts; rotates inferiorly Rhomboid major Thoracic vertebrae (T2–T5) Medial border of scapula Posterior thorax Stabilizes scapula during pectoral girdle movement Scapula Retracts; rotates inferiorly Rhomboid minor Cervical and thoracic vertebrae (C7 and T1) Medial border of scapula Table 11.8 Muscles That Move the Humerus Similar to the muscles that position the pectoral girdle, muscles that cross the shoulder joint and move the humerus bone of the arm include both axial and scapular muscles ( Figure 11.23 and Figure 11.24 ). The two axial muscles are the pectoralis major and the latissimus dorsi. The pectoralis major is thick and fan-shaped, covering much of the superior portion of the anterior thorax. The broad, triangular latissimus dorsi is located on the inferior part of the back, where it inserts into a thick connective tissue shealth called an aponeurosis. The rest of the shoulder muscles originate on the scapula. The anatomical and ligamental structure of the shoulder joint and the arrangements of the muscles covering it, allows the arm to carry out different types of movements. The deltoid , the thick muscle that creates the rounded lines of the shoulder is the major abductor of the arm, but it also facilitates flexing and medial rotation, as well as extension and lateral rotation. The subscapularis originates on the anterior scapula and medially rotates the arm. Named for their locations, the supraspinatus (superior to the spine of the scapula) and the infraspinatus (inferior to the spine of the scapula) abduct the arm, and laterally rotate the arm, respectively. The thick and flat teres major is inferior to the teres minor and extends the arm, and assists in adduction and medial rotation of it. The long teres minor laterally rotates and extends the arm. Finally, the coracobrachialis flexes and adducts the arm. The tendons of the deep subscapularis, supraspinatus, infraspinatus, and teres minor connect the scapula to the humerus, forming the rotator cuff (musculotendinous cuff), the circle of tendons around the shoulder joint. When baseball pitchers undergo shoulder surgery it is usually on the rotator cuff, which becomes pinched and inflamed, and may tear away from the bone due to the repetitive motion of bring the arm overhead to throw a fast pitch. Muscles That Move the Forearm The forearm, made of the radius and ulna bones, has four main types of action at the hinge of the elbow joint: flexion, extension, pronation, and supination. The forearm flexors include the biceps brachii, brachialis, and brachioradialis. The extensors are the triceps brachii and anconeus . The pronators are the pronator teres and the pronator quadratus , and the supinator is the only one that turns the forearm anteriorly. When the forearm faces anteriorly, it is supinated. When the forearm faces posteriorly, it is pronated. The biceps brachii, brachialis, and brachioradialis flex the forearm. The two-headed biceps brachii crosses the shoulder and elbow joints to flex the forearm, also taking part in supinating the forearm at the radioulnar joints and flexing the arm at the shoulder joint. Deep to the biceps brachii, the brachialis provides additional power in flexing the forearm. Finally, the brachioradialis can flex the forearm quickly or help lift a load slowly. These muscles and their associated blood vessels and nerves form the anterior compartment of the arm (anterior flexor compartment of the arm) ( Figure 11.25 and Figure 11.26 ). Muscles That Move the Wrist, Hand, and Fingers Wrist, hand, and finger movements are facilitated by two groups of muscles. The forearm is the origin of the extrinsic muscles of the hand . The palm is the origin of the intrinsic muscles of the hand. Muscles of the Arm That Move the Wrists, Hands, and Fingers The muscles in the anterior compartment of the forearm (anterior flexor compartment of the forearm) originate on the humerus and insert onto different parts of the hand. These make up the bulk of the forearm. From lateral to medial, the superficial anterior compartment of the forearm includes the flexor carpi radialis , palmaris longus , flexor carpi ulnaris , and flexor digitorum superficialis . The flexor digitorum superficialis flexes the hand as well as the digits at the knuckles, which allows for rapid finger movements, as in typing or playing a musical instrument (see Figure 11.27 and Table 11.9 ). However, poor ergonomics can irritate the tendons of these muscles as they slide back and forth with the carpal tunnel of the anterior wrist and pinch the median nerve, which also travels through the tunnel, causing Carpal Tunnel Syndrome. The deep anterior compartment produces flexion and bends fingers to make a fist. These are the flexor pollicis longus and the flexor digitorum profundus . The muscles in the superficial posterior compartment of the forearm (superficial posterior extensor compartment of the forearm) originate on the humerus. These are the extensor radialis longus , extensor carpi radialis brevis , extensor digitorum , extensor digiti minimi , and the extensor carpi ulnaris . The muscles of the deep posterior compartment of the forearm (deep posterior extensor compartment of the forearm) originate on the radius and ulna. These include the abductor pollicis longus , extensor pollicis brevis , extensor pollicis longus , and extensor indicis (see Figure 11.27 ). The tendons of the forearm muscles attach to the wrist and extend into the hand. Fibrous bands called retinacula sheath the tendons at the wrist. The flexor retinaculum extends over the palmar surface of the hand while the extensor retinaculum extends over the dorsal surface of the hand. Intrinsic Muscles of the Hand The intrinsic muscles of the hand both originate and insert within it ( Figure 11.28 ). These muscles allow your fingers to also make precise movements for actions, such as typing or writing. These muscles are divided into three groups. The thenar muscles are on the radial aspect of the palm. The hypothenar muscles are on the medial aspect of the palm, and the intermediate muscles are midpalmar. The thenar muscles include the abductor pollicis brevis , opponens pollicis , flexor pollicis brevis , and the adductor pollicis . These muscles form the thenar eminence , the rounded contour of the base of the thumb, and all act on the thumb. The movements of the thumb play an integral role in most precise movements of the hand. The hypothenar muscles include the abductor digiti minimi , flexor digiti minimi brevis , and the opponens digiti minimi . These muscles form the hypothenar eminence , the rounded contour of the little finger, and as such, they all act on the little finger. Finally, the intermediate muscles act on all the fingers and include the lumbrical , the palmar interossei , and the dorsal interossei . Intrinsic Muscles of the Hand Muscle Movement Target Target motion direction Prime mover Origin Insertion Thenar muscles Moves thumb toward body Thumb Abduction Abductor pollicis brevis Flexor retinaculum; and nearby carpals Lateral base of proximal phalanx of thumb Thenar muscles Moves thumb across palm to touch other fingers Thumb Opposition Opponens pollicis Flexor retinaculum; trapezium Anterior of first metacarpal Thenar muscles Flexes thumb Thumb Flexion Flexor pollicis brevis Flexor retinaculum; trapezium Lateral base of proximal phalanx of thumb Thenar muscles Moves thumb away from body Thumb Adduction Adductor pollicis Capitate bone; bases of metacarpals 2–4; front of metacarpal 3 Medial base of proximal phalanx of thumb Hypothenar muscles Moves little finger toward body Little finger Abduction Abductor digiti minimi Pisiform bone Medial side of proximal phalanx of little finger Hypothenar muscles Flexes little finger Little finger Flexion Flexor digiti minimi brevis Hamate bone; flexor retinaculum Medial side of proximal phalanx of little finger Hypothenar muscles Moves little finger across palm to touch thumb Little finger Opposition Opponens digiti minimi Hamate bone; flexor retinaculum Medial side of fifth metacarpal Intermediate muscles Flexes each finger at metacarpo-phalangeal joints; extends each finger at interphalangeal joints Fingers Flexion Lumbricals Palm (lateral sides of tendons in flexor digitorum profundus) Fingers 2–5 (lateral edges of extensional expansions on first phalanges) Intermediate muscles Adducts and flexes each finger at metacarpo-phalangeal joints; extends each finger at interphalangeal joints Fingers Adduction; flexion; extension Palmar interossei Side of each metacarpal that faces metacarpal 3 (absent from metacarpal 3) Extensor expansion on first phalanx of each finger (except finger 3) on side facing finger 3 Intermediate muscles Abducts and flexes the three middle fingers at metacarpo-phalangeal joints; extends the three middle fingers at interphalangeal joints Fingers Abduction; flexion; extension Dorsal interossei Sides of metacarpals Both sides of finger 3; for each other finger, extensor expansion over first phalanx on side opposite finger 3 Table 11.9 11.6 Appendicular Muscles of the Pelvic Girdle and Lower Limbs Learning Objectives By the end of this section, you will be able to: Identify the appendicular muscles of the pelvic girdle and lower limb Identify the movement and function of the pelvic girdle and lower limb The appendicular muscles of the lower body position and stabilize the pelvic girdle , which serves as a foundation for the lower limbs. Comparatively, there is much more movement at the pectoral girdle than at the pelvic girdle. There is very little movement of the pelvic girdle because of its connection with the sacrum at the base of the axial skeleton. The pelvic girdle is less range of motion because it was designed to stabilize and support the body. Muscles of the Thigh What would happen if the pelvic girdle, which attaches the lower limbs to the torso, were capable of the same range of motion as the pectoral girdle? For one thing, walking would expend more energy if the heads of the femurs were not secured in the acetabula of the pelvis. The body’s center of gravity is in the area of the pelvis. If the center of gravity were not to remain fixed, standing up would be difficult as well. Therefore, what the leg muscles lack in range of motion and versatility, they make up for in size and power, facilitating the body’s stabilization, posture, and movement. Gluteal Region Muscles That Move the Femur Most muscles that insert on the femur (the thigh bone) and move it, originate on the pelvic girdle. The psoas major and iliacus make up the iliopsoas group . Some of the largest and most powerful muscles in the body are the gluteal muscles or gluteal group . The gluteus maximus is the largest; deep to the gluteus maximus is the gluteus medius , and deep to the gluteus medius is the gluteus minimus , the smallest of the trio ( Figure 11.29 and Figure 11.30 ). The tensor fascia latae is a thick, squarish muscle in the superior aspect of the lateral thigh. It acts as a synergist of the gluteus medius and iliopsoas in flexing and abducting the thigh. It also helps stabilize the lateral aspect of the knee by pulling on the iliotibial tract (band), making it taut. Deep to the gluteus maximus, the piriformis , obturator internus , obturator externus , superior gemellus , inferior gemellus , and quadratus femoris laterally rotate the femur at the hip. The adductor longus , adductor brevis , and adductor magnus can both medially and laterally rotate the thigh depending on the placement of the foot. The adductor longus flexes the thigh, whereas the adductor magnus extends it. The pectineus adducts and flexes the femur at the hip as well. The pectineus is located in the femoral triangle , which is formed at the junction between the hip and the leg and also includes the femoral nerve, the femoral artery, the femoral vein, and the deep inguinal lymph nodes. Thigh Muscles That Move the Femur, Tibia, and Fibula Deep fascia in the thigh separates it into medial, anterior, and posterior compartments (see Figure 11.29 and Figure 11.31 ). The muscles in the medial compartment of the thigh are responsible for adducting the femur at the hip. Along with the adductor longus, adductor brevis, adductor magnus, and pectineus, the strap-like gracilis adducts the thigh in addition to flexing the leg at the knee. The muscles of the anterior compartment of the thigh flex the thigh and extend the leg. This compartment contains the quadriceps femoris group , which actually comprises four muscles that extend and stabilize the knee. The rectus femoris is on the anterior aspect of the thigh, the vastus lateralis is on the lateral aspect of the thigh, the vastus medialis is on the medial aspect of the thigh, and the vastus intermedius is between the vastus lateralis and vastus medialis and deep to the rectus femoris. The tendon common to all four is the quadriceps tendon (patellar tendon), which inserts into the patella and continues below it as the patellar ligament . The patellar ligament attaches to the tibial tuberosity. In addition to the quadriceps femoris, the sartorius is a band-like muscle that extends from the anterior superior iliac spine to the medial side of the proximal tibia. This versatile muscle flexes the leg at the knee and flexes, abducts, and laterally rotates the leg at the hip. This muscle allows us to sit cross-legged. The posterior compartment of the thigh includes muscles that flex the leg and extend the thigh. The three long muscles on the back of the knee are the hamstring group , which flexes the knee. These are the biceps femoris , semitendinosus , and semimembranosus . The tendons of these muscles form the popliteal fossa , the diamond-shaped space at the back of the knee. Muscles That Move the Feet and Toes Similar to the thigh muscles, the muscles of the leg are divided by deep fascia into compartments, although the leg has three: anterior, lateral, and posterior ( Figure 11.32 and Figure 11.33 ). The muscles in the anterior compartment of the leg : the tibialis anterior , a long and thick muscle on the lateral surface of the tibia, the extensor hallucis longus , deep under it, and the extensor digitorum longus , lateral to it, all contribute to raising the front of the foot when they contract. The fibularis tertius , a small muscle that originates on the anterior surface of the fibula, is associated with the extensor digitorum longus and sometimes fused to it, but is not present in all people. Thick bands of connective tissue called the superior extensor retinaculum (transverse ligament of the ankle) and the inferior extensor retinaculum , hold the tendons of these muscles in place during dorsiflexion. The lateral compartment of the leg includes two muscles: the fibularis longus (peroneus longus) and the fibularis brevis (peroneus brevis). The superficial muscles in the posterior compartment of the leg all insert onto the calcaneal tendon (Achilles tendon), a strong tendon that inserts into the calcaneal bone of the ankle. The muscles in this compartment are large and strong and keep humans upright. The most superficial and visible muscle of the calf is the gastrocnemius . Deep to the gastrocnemius is the wide, flat soleus . The plantaris runs obliquely between the two; some people may have two of these muscles, whereas no plantaris is observed in about seven percent of other cadaver dissections. The plantaris tendon is a desirable substitute for the fascia lata in hernia repair, tendon transplants, and repair of ligaments. There are four deep muscles in the posterior compartment of the leg as well: the popliteus , flexor digitorum longus , flexor hallucis longus , and tibialis posterior . The foot also has intrinsic muscles, which originate and insert within it (similar to the intrinsic muscles of the hand). These muscles primarily provide support for the foot and its arch, and contribute to movements of the toes ( Figure 11.34 and Figure 11.35 ). The principal support for the longitudinal arch of the foot is a deep fascia called plantar aponeurosis , which runs from the calcaneus bone to the toes (inflammation of this tissue is the cause of “plantar fasciitis,” which can affect runners. The intrinsic muscles of the foot consist of two groups. The dorsal group includes only one muscle, the extensor digitorum brevis . The second group is the plantar group , which consists of four layers, starting with the most superficial.
microbiology
Summary 22.1 Anatomy and Normal Microbiota of the Respiratory Tract The respiratory tract is divided into upper and lower regions at the epiglottis . Air enters the upper respiratory tract through the nasal cavity and mouth, which both lead to the pharynx . The lower respiratory tract extends from the larynx into the trachea before branching into the bronchi , which divide further to form the bronchioles , which terminate in alveoli , where gas exchange occurs. The upper respiratory tract is colonized by an extensive and diverse normal microbiota, many of which are potential pathogens. Few microbial inhabitants have been found in the lower respiratory tract, and these may be transients. Members of the normal microbiota may cause opportunistic infections, using a variety of strategies to overcome the innate nonspecific defenses (including the mucociliary escalator) and adaptive specific defenses of the respiratory system. Effective vaccines are available for many common respiratory pathogens, both bacterial and viral. Most respiratory infections result in inflammation of the infected tissues; these conditions are given names ending in -itis , such as rhinitis , sinusitis , otitis , pharyngitis , and bronchitis . 22.2 Bacterial Infections of the Respiratory Tract A wide variety of bacteria can cause respiratory diseases; most are treatable with antibiotics or preventable with vaccines. Streptococcus pyogenes causes strep throat , an infection of the pharynx that also causes high fever and can lead to scarlet fever , acute rheumatic fever , and acute glomerulonephritis . Acute otitis media is an infection of the middle ear that may be caused by several bacteria, including Streptococcus pneumoniae, Haemophilus influenzae, and Moraxella catarrhalis . The infection can block the eustachian tubes, leading to otitis media with effusion . Diphtheria , caused by Corynebacterium diphtheriae , is now a rare disease because of widespread vaccination. The bacteria produce exotoxins that kill cells in the pharynx, leading to the formation of a pseudomembrane ; and damage other parts of the body. Bacterial pneumonia results from infections that cause inflammation and fluid accumulation in the alveoli. It is most commonly caused by S. pneumoniae or H. influenzae . The former is commonly multidrug resistant. Mycoplasma pneumonia results from infection by Mycoplasma pneumoniae ; it can spread quickly, but the disease is mild and self-limiting. Chlamydial pneumonia can be caused by three pathogens that are obligate intracellular parasites. Chlamydophila pneumoniae is typically transmitted from an infected person, whereas C. psittaci is typically transmitted from an infected bird. Chlamydia trachomatis , may cause pneumonia in infants. Several other bacteria can cause pneumonia in immunocompromised individuals and those with cystic fibrosis. Tuberculosis is caused by Mycobacterium tuberculosis . Infection leads to the production of protective tubercles in the alveoli and calcified Ghon complexes that can harbor the bacteria for a long time. Antibiotic-resistant forms are common and treatment is typically long term. Pertussis is caused by Bordetella pertussis . Mucus accumulation in the lungs leads to prolonged severe coughing episodes (whooping cough) that facilitate transmission. Despite an available vaccine, outbreaks are still common. Legionnaires disease is caused by infection from environmental reservoirs of the Legionella pneumophila bacterium. The bacterium is endocytic within macrophages and infection can lead to pneumonia, particularly among immunocompromised individuals. Q fever is caused by Coxiella burnetii , whose primary hosts are domesticated mammals (zoonotic disease). It causes pneumonia primarily in farm workers and can lead to serious complications, such as endocarditis. 22.3 Viral Infections of the Respiratory Tract Viruses cause respiratory tract infections more frequently than bacteria, and most viral infections lead to mild symptoms. The common cold can be caused by more than 200 viruses, typically rhinoviruses, coronaviruses, and adenoviruses, transmitted by direct contact, aerosols, or environmental surfaces. Due to its ability to rapidly mutate through antigenic drift and antigenic shift , influenza remains an important threat to human health. Two new influenza vaccines are developed annually. Several viral infections, including respiratory syncytial virus infections, which frequently occur in the very young, can begin with mild symptoms before progressing to viral pneumonia. SARS and MERS are acute respiratory infections caused by coronaviruses, and both appear to originate in animals. SARS has not been seen in the human population since 2004 but had a high mortality rate during its outbreak. MERS also has a high mortality rate and continues to appear in human populations. Measles , rubella , and chickenpox are highly contagious, systemic infections that gain entry through the respiratory system and cause rashes and fevers. Vaccines are available for all three. Measles is the most severe of the three and is responsible for significant mortality around the world. Chickenpox typically causes mild infections in children but the virus can reactivate to cause painful cases of shingles later in life. 22.4 Respiratory Mycoses Fungal pathogens rarely cause respiratory disease in healthy individuals, but inhalation of fungal spores can cause severe pneumonia and systemic infections in immunocompromised patients. Antifungal drugs like amphotericin B can control most fungal respiratory infections. Histoplasmosis is caused by a mold that grows in soil rich in bird or bat droppings. Few exposed individuals become sick, but vulnerable individuals are susceptible. The yeast-like infectious cells grow inside phagocytes. Coccidioidomycosis is also acquired from soil and, in some individuals, will cause lesions on the face. Extreme cases may infect other organs, causing death. Blastomycosis , a rare disease caused by a soil fungus, typically produces a mild lung infection but can become disseminated in the immunocompromised. Systemic cases are fatal if untreated. Mucormycosis is a rare disease, caused by fungi of the order Mucorales. It primarily affects immunocompromised people. Infection involves growth of the hyphae into infected tissues and can lead to death in some cases. Aspergillosis , caused by the common soil fungus Aspergillus , infects immunocompromised people. Hyphal balls may impede lung function and hyphal growth into tissues can cause damage. Disseminated forms can lead to death. Pneumocystis pneumonia is caused by the fungus P. jirovecii . The disease is found in patients with AIDS and other immunocompromised individuals. Sulfa drug treatments have side effects, but untreated cases may be fatal. Cryptococcosis is caused by Cryptococcus neoformans . Lung infections may move to the brain, causing meningitis, which can be fatal.
Chapter Outline 22.1 Anatomy and Normal Microbiota of the Respiratory Tract 22.2 Bacterial Infections of the Respiratory Tract 22.3 Viral Infections of the Respiratory Tract 22.4 Respiratory Mycoses Introduction The respiratory tract is one of the main portals of entry into the human body for microbial pathogens. On average, a human takes about 20,000 breaths each day. This roughly corresponds to 10,000 liters, or 10 cubic meters, of air. Suspended within this volume of air are millions of microbes of terrestrial, animal, and human origin—including many potential pathogens. A few of these pathogens will cause relatively mild infections like sore throats and colds. Others, however, are less benign. According to the World Health Organization, respiratory tract infections such as tuberculosis, influenza, and pneumonia were responsible for more than 4 million deaths worldwide in 2012. 1 1 World Health Organization. “The Top Ten Causes of Death.” May 2014. http://www.who.int/mediacentre/factsheets/fs310/en/ At one time, it was thought that antimicrobial drugs and preventive vaccines might hold respiratory infections in check in the developed world, but recent developments suggest otherwise. The rise of multiple-antibiotic resistance in organisms like Mycobacterium tuberculosis has rendered many of our modern drugs ineffective. In addition, there has been a recent resurgence in diseases like whooping cough and measles, once-common childhood illnesses made rare by effective vaccines. Despite advances in medicine and public health programs, it is likely that respiratory pathogens will remain formidable adversaries for the foreseeable future.
[ { "answer": { "ans_choice": 2, "ans_text": "C" }, "bloom": null, "hl_context": "The respiratory system can be conceptually divided into upper and lower regions at the point of the epiglottis , the structure that seals off the lower respiratory system from the pharynx during swallowing ( Figure 22.2 ) . The upper respiratory system is in direct contact with the external environment . The nares ( or nostrils ) are the external openings of the nose that lead back into the nasal cavity , a large air-filled space behind the nares . These anatomical sites constitute the primary opening and first section of the respiratory tract , respectively . The nasal cavity is lined with hairs that trap large particles , like dust and pollen , and prevent their access to deeper tissues . The nasal cavity is also lined with a mucous membrane and Bowman ’ s glands that produce mucus to help trap particles and microorganisms for removal . The nasal cavity is connected to several other air-filled spaces . The sinuses , a set of four , paired small cavities in the skull , communicate with the nasal cavity through a series of small openings . <hl> The nasopharynx is part of the upper throat extending from the posterior nasal cavity . <hl> <hl> The nasopharynx carries air inhaled through the nose . <hl> <hl> The middle ear is connected to the nasopharynx through the eustachian tube . <hl> <hl> The middle ear is separated from the outer ear by the tympanic membrane , or ear drum . <hl> <hl> And finally , the lacrimal glands drain to the nasal cavity through the nasolacrimal ducts ( tear ducts ) . <hl> <hl> The open connections between these sites allow microorganisms to move from the nasal cavity to the sinuses , middle ears ( and back ) , and down into the lower respiratory tract from the nasopharynx . <hl>", "hl_sentences": "The nasopharynx is part of the upper throat extending from the posterior nasal cavity . The nasopharynx carries air inhaled through the nose . The middle ear is connected to the nasopharynx through the eustachian tube . The middle ear is separated from the outer ear by the tympanic membrane , or ear drum . And finally , the lacrimal glands drain to the nasal cavity through the nasolacrimal ducts ( tear ducts ) . The open connections between these sites allow microorganisms to move from the nasal cavity to the sinuses , middle ears ( and back ) , and down into the lower respiratory tract from the nasopharynx .", "question": { "cloze_format": "The ___ is/are not directly connected to the nasopharynx.", "normal_format": "Which of the following is not directly connected to the nasopharynx?", "question_choices": [ "middle ear", "oropharynx", "lacrimal glands", "nasal cavity" ], "question_id": "fs-id1167661282290", "question_text": "Which of the following is not directly connected to the nasopharynx?" }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 0, "ans_text": "A" }, "bloom": null, "hl_context": "<hl> The inner lining of the respiratory system consists of mucous membrane s ( Figure 22.4 ) and is protected by multiple immune defenses . <hl> <hl> The goblet cell s within the respiratory epithelium secrete a layer of sticky mucus . <hl> The viscosity and acidity of this secretion inhibits microbial attachment to the underlying cells . In addition , the respiratory tract contains ciliated epithelial cells . The beating cilia dislodge and propel the mucus , and any trapped microbes , upward to the epiglottis , where they will be swallowed . Elimination of microbes in this manner is referred to as the mucociliary escalator effect and is an important mechanism that prevents inhaled microorganisms from migrating further into the lower respiratory tract .", "hl_sentences": "The inner lining of the respiratory system consists of mucous membrane s ( Figure 22.4 ) and is protected by multiple immune defenses . The goblet cell s within the respiratory epithelium secrete a layer of sticky mucus .", "question": { "cloze_format": "The cells that produce the mucus for the mucous membranes are the ___ .", "normal_format": "What type of cells produce the mucus for the mucous membranes?", "question_choices": [ "goblet cells", "macrophages", "phagocytes", "ciliated epithelial cells" ], "question_id": "fs-id1167661316152", "question_text": "What type of cells produce the mucus for the mucous membranes?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 1, "ans_text": "B" }, "bloom": null, "hl_context": "<hl> The lower respiratory system begins below the epiglottis in the larynx or voice box ( Figure 22.3 ) . <hl> <hl> The trachea , or windpipe , is a cartilaginous tube extending from the larynx that provides an unobstructed path for air to reach the lungs . <hl> <hl> The trachea bifurcates into the left and right bronchi as it reaches the lungs . <hl> These paths branch repeatedly to form smaller and more extensive networks of tubes , the bronchiole s . The terminal bronchioles formed in this tree-like network end in cul-de-sacs called the alveoli . These structures are surrounded by capillary networks and are the site of gas exchange in the respiratory system . Human lungs contain on the order of 400,000 , 000 alveoli . The outer surface of the lungs is protected with a double-layered pleural membrane . This structure protects the lungs and provides lubrication to permit the lungs to move easily during respiration . The oral cavity is a secondary opening for the respiratory tract . The oral and nasal cavities connect through the fauces to the pharynx , or throat . <hl> The pharynx can be divided into three regions : the nasopharynx , the oropharynx , and the laryngopharynx . <hl> Air inhaled through the mouth does not pass through the nasopharynx ; it proceeds first through the oropharynx and then through the laryngopharynx . The palatine tonsils , which consist of lymphoid tissue , are located within the oropharynx . <hl> The laryngopharynx , the last portion of the pharynx , connects to the larynx , which contains the vocal fold ( Figure 22.2 ) . <hl>", "hl_sentences": "The lower respiratory system begins below the epiglottis in the larynx or voice box ( Figure 22.3 ) . The trachea , or windpipe , is a cartilaginous tube extending from the larynx that provides an unobstructed path for air to reach the lungs . The trachea bifurcates into the left and right bronchi as it reaches the lungs . The pharynx can be divided into three regions : the nasopharynx , the oropharynx , and the laryngopharynx . The laryngopharynx , the last portion of the pharynx , connects to the larynx , which contains the vocal fold ( Figure 22.2 ) .", "question": { "cloze_format": "___ correctly orders the structures through which air passes during inhalation.", "normal_format": "Which of these correctly orders the structures through which air passes during inhalation?", "question_choices": [ "pharynx → trachea → larynx → bronchi", "pharynx → larynx → trachea → bronchi", "larynx → pharynx → bronchi → trachea", "larynx → pharynx → trachea → bronchi" ], "question_id": "fs-id1167663658660", "question_text": "Which of these correctly orders the structures through which air passes during inhalation?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 2, "ans_text": "C" }, "bloom": null, "hl_context": "<hl> The respiratory system can be conceptually divided into upper and lower regions at the point of the epiglottis , the structure that seals off the lower respiratory system from the pharynx during swallowing ( Figure 22.2 ) . <hl> The upper respiratory system is in direct contact with the external environment . The nares ( or nostrils ) are the external openings of the nose that lead back into the nasal cavity , a large air-filled space behind the nares . These anatomical sites constitute the primary opening and first section of the respiratory tract , respectively . The nasal cavity is lined with hairs that trap large particles , like dust and pollen , and prevent their access to deeper tissues . The nasal cavity is also lined with a mucous membrane and Bowman ’ s glands that produce mucus to help trap particles and microorganisms for removal . The nasal cavity is connected to several other air-filled spaces . The sinuses , a set of four , paired small cavities in the skull , communicate with the nasal cavity through a series of small openings . The nasopharynx is part of the upper throat extending from the posterior nasal cavity . The nasopharynx carries air inhaled through the nose . The middle ear is connected to the nasopharynx through the eustachian tube . The middle ear is separated from the outer ear by the tympanic membrane , or ear drum . And finally , the lacrimal glands drain to the nasal cavity through the nasolacrimal ducts ( tear ducts ) . The open connections between these sites allow microorganisms to move from the nasal cavity to the sinuses , middle ears ( and back ) , and down into the lower respiratory tract from the nasopharynx .", "hl_sentences": "The respiratory system can be conceptually divided into upper and lower regions at the point of the epiglottis , the structure that seals off the lower respiratory system from the pharynx during swallowing ( Figure 22.2 ) .", "question": { "cloze_format": "The ___________ separates the upper and lower respiratory tract.", "normal_format": "What separates the upper and lower respiratory tract?", "question_choices": [ "bronchi", "larynx", "epiglottis", "palatine tonsil" ], "question_id": "fs-id1167663988384", "question_text": "The ___________ separates the upper and lower respiratory tract." }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 0, "ans_text": "A" }, "bloom": null, "hl_context": "Many members of the respiratory system ’ s normal microbiota are opportunistic pathogens . <hl> To proliferate and cause host damage , they first must overcome the immune defenses of respiratory tissues . <hl> <hl> Many mucosal pathogens produce virulence factors such as adhesin s that mediate attachment to host epithelial cells , or polysaccharide capsules that allow microbes to evade phagocytosis . <hl> The endotoxin s of gram-negative bacteria can stimulate a strong inflammatory response that damages respiratory cells . Other pathogens produce exotoxin s , and still others have the ability to survive within the host cells . Once an infection of the respiratory tract is established , it tends to impair the mucociliary escalator , limiting the body ’ s ability to expel the invading microbes , thus making it easier for pathogens to multiply and spread .", "hl_sentences": "To proliferate and cause host damage , they first must overcome the immune defenses of respiratory tissues . Many mucosal pathogens produce virulence factors such as adhesin s that mediate attachment to host epithelial cells , or polysaccharide capsules that allow microbes to evade phagocytosis .", "question": { "cloze_format": "The microbial virulence factor that is most important for attachment to host respiratory tissues is ___.", "normal_format": "Which microbial virulence factor is most important for attachment to host respiratory tissues?", "question_choices": [ "adhesins", "lipopolysaccharide", "hyaluronidase", "capsules" ], "question_id": "fs-id1167663922225", "question_text": "Which microbial virulence factor is most important for attachment to host respiratory tissues?" }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 0, "ans_text": "A" }, "bloom": null, "hl_context": "<hl> The zoonotic disease Q fever is caused by a rickettsia , Coxiella burnetii . <hl> The primary reservoirs for this bacterium are domesticated livestock such as cattle , sheep , and goats . The bacterium may be transmitted by ticks or through exposure to the urine , feces , milk , or amniotic fluid of an infected animal . In humans , the primary route of infection is through inhalation of contaminated farmyard aerosols . It is , therefore , largely an occupational disease of farmers . Humans are acutely sensitive to C . burnetii — the infective dose is estimated to be just a few cells . 15 In addition , the organism is hardy and can survive in a dry environment for an extended time . Symptoms associated with acute Q fever include high fever , headache , coughing , pneumonia , and general malaise . In a small number of patients ( less than 5 % 16 ) , the condition may become chronic , often leading to endocarditis , which may be fatal . 15 WD Tigertt et al . “ Airborne Q Fever . ” Bacteriological Reviews 25 no . 3 ( 1961 ): 285 – 293 . 16 Centers for Disease Control and Prevention . “ Q fever . Symptoms , Diagnosis , and Treatment . ” 2013 . http://www.cdc.gov/qfever/symptoms/index.html . Accessed July 6 , 2016 .", "hl_sentences": "The zoonotic disease Q fever is caused by a rickettsia , Coxiella burnetii .", "question": { "cloze_format": "The ___ disease is caused by Coxiella burnetii.", "normal_format": "What disease is caused by Coxiella burnetii?", "question_choices": [ "Q fever", "tuberculosis", "diphtheria", "walking pneumonia" ], "question_id": "fs-id1167661432828", "question_text": "What disease is caused by Coxiella burnetii?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 2, "ans_text": "C" }, "bloom": null, "hl_context": "<hl> A pertussis infection can be divided into three distinct stages . <hl> The initial infection , termed the catarrhal stage , is relatively mild and unremarkable . The signs and symptoms may include nasal congestion , a runny nose , sneezing , and a low-grade fever . This , however , is the stage in which B . pertussis is most infectious . <hl> In the paroxysmal stage , mucus accumulation leads to uncontrollable coughing spasms that can last for several minutes and frequently induce vomiting . <hl> <hl> The paroxysmal stage can last for several weeks . <hl> A long convalescence stage follows the paroxysmal stage , during which time patients experience a chronic cough that can last for up to several months . In fact , the disease is sometimes called the 100 - day cough .", "hl_sentences": "A pertussis infection can be divided into three distinct stages . In the paroxysmal stage , mucus accumulation leads to uncontrollable coughing spasms that can last for several minutes and frequently induce vomiting . The paroxysmal stage can last for several weeks .", "question": { "cloze_format": "The characteristic whooping sound is made in the ___ stage of pertussis.", "normal_format": "In which stage of pertussis is the characteristic whooping sound made?", "question_choices": [ "convalescence", "catarrhal", "paroxysmal", "prodromal" ], "question_id": "fs-id1167663995231", "question_text": "In which stage of pertussis is the characteristic whooping sound made?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 0, "ans_text": "A" }, "bloom": null, "hl_context": "<hl> The zoonotic disease Q fever is caused by a rickettsia , Coxiella burnetii . <hl> The primary reservoirs for this bacterium are domesticated livestock such as cattle , sheep , and goats . The bacterium may be transmitted by ticks or through exposure to the urine , feces , milk , or amniotic fluid of an infected animal . In humans , the primary route of infection is through inhalation of contaminated farmyard aerosols . It is , therefore , largely an occupational disease of farmers . Humans are acutely sensitive to C . burnetii — the infective dose is estimated to be just a few cells . 15 In addition , the organism is hardy and can survive in a dry environment for an extended time . Symptoms associated with acute Q fever include high fever , headache , coughing , pneumonia , and general malaise . In a small number of patients ( less than 5 % 16 ) , the condition may become chronic , often leading to endocarditis , which may be fatal . 15 WD Tigertt et al . “ Airborne Q Fever . ” Bacteriological Reviews 25 no . 3 ( 1961 ): 285 – 293 . 16 Centers for Disease Control and Prevention . “ Q fever . Symptoms , Diagnosis , and Treatment . ” 2013 . http://www.cdc.gov/qfever/symptoms/index.html . Accessed July 6 , 2016 .", "hl_sentences": "The zoonotic disease Q fever is caused by a rickettsia , Coxiella burnetii .", "question": { "cloze_format": "___ are the causative agent of Q fever.", "normal_format": "What is the causative agent of Q fever?", "question_choices": [ "Coxiella burnetii", "Chlamydophila psittaci", "Mycoplasma pneumoniae", "Streptococcus pyogenes" ], "question_id": "fs-id1167661366235", "question_text": "What is the causative agent of Q fever?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 2, "ans_text": "C" }, "bloom": null, "hl_context": "<hl> Primary atypical pneumonia is caused by Mycoplasma pneumoniae . <hl> <hl> This bacterium is not part of the respiratory tract ’ s normal microbiota and can cause epidemic disease outbreaks . <hl> <hl> Also known as walking pneumonia , mycoplasma pneumonia infections are common in crowded environments like college campuses and military bases . <hl> It is spread by aerosols formed when coughing or sneezing . The disease is often mild , with a low fever and persistent cough . These bacteria , which do not have cell walls , use a specialized attachment organelle to bind to ciliated cells . In the process , epithelial cells are damaged and the proper function of the cilia is hindered ( Figure 22.12 ) .", "hl_sentences": "Primary atypical pneumonia is caused by Mycoplasma pneumoniae . This bacterium is not part of the respiratory tract ’ s normal microbiota and can cause epidemic disease outbreaks . Also known as walking pneumonia , mycoplasma pneumonia infections are common in crowded environments like college campuses and military bases .", "question": { "cloze_format": "The microbe that causes “walking pneumonia” is ___.", "normal_format": "Which of these microbes causes “walking pneumonia”?", "question_choices": [ "Klebsiella pneumoniae", "Streptococcus pneumoniae", "Mycoplasma pneumoniae", "Chlamydophila pneumoniae" ], "question_id": "fs-id1167661330550", "question_text": "Which of these microbes causes “walking pneumonia”?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 3, "ans_text": "D" }, "bloom": null, "hl_context": "<hl> The common cold is a generic term for a variety of mild viral infections of the nasal cavity . <hl> More than 200 different viruses are known to cause the common cold . <hl> The most common groups of cold viruses include rhinovirus es , coronavirus es , and adenovirus es . <hl> These infections are widely disseminated in the human population and are transmitted through direct contact and droplet transmission . Coughing and sneezing efficiently produce infectious aerosols , and rhinoviruses are known to persist on environmental surfaces for up to a week . 17 17 AG L ’ Huillier et al . “ Survival of Rhinoviruses on Human Fingers . ” Clinical Microbiology and Infection 21 , no . 4 ( 2015 ): 381 – 385 .", "hl_sentences": "The common cold is a generic term for a variety of mild viral infections of the nasal cavity . The most common groups of cold viruses include rhinovirus es , coronavirus es , and adenovirus es .", "question": { "cloze_format": "The ___ is a virus that is not commonly associated with the common cold.", "normal_format": "Which of the following viruses is not commonly associated with the common cold?", "question_choices": [ "coronavirus", "adenovirus", "rhinovirus", "varicella-zoster virus" ], "question_id": "fs-id1167661326769", "question_text": "Which of the following viruses is not commonly associated with the common cold?" }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 0, "ans_text": "A" }, "bloom": null, "hl_context": "<hl> Eye on Ethics Smallpox Stockpiles Smallpox has probably killed more humans than any other infectious disease , with the possible exception of tuberculosis . <hl> This disease , caused by the variola major virus , is transmitted by inhalation of viral particles shed from lesions in the throat . The smallpox virus spreads systemically in the bloodstream and produces a pustular skin rash . Historical epidemics of smallpox had fatality rates of 50 % or greater in susceptible populations . <hl> Concerted worldwide vaccination efforts eradicated smallpox from the general population in 1977 . <hl> <hl> This was the first microbial disease in history to be eradicated , a feat made possible by the fact that the only reservoir for the smallpox virus is infected humans . <hl>", "hl_sentences": "Eye on Ethics Smallpox Stockpiles Smallpox has probably killed more humans than any other infectious disease , with the possible exception of tuberculosis . Concerted worldwide vaccination efforts eradicated smallpox from the general population in 1977 . This was the first microbial disease in history to be eradicated , a feat made possible by the fact that the only reservoir for the smallpox virus is infected humans .", "question": { "cloze_format": "The ___ is a viral disease that has been eliminated from the general population worldwide.", "normal_format": "Which of the following viral diseases has been eliminated from the general population worldwide?", "question_choices": [ "smallpox", "measles", "German measles", "influenza" ], "question_id": "fs-id1167661425196", "question_text": "Which of the following viral diseases has been eliminated from the general population worldwide?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 3, "ans_text": "D" }, "bloom": null, "hl_context": "Respiratory syncytial virus ( RSV ) infections are fairly common in infants ; most people have been infected by the age of 2 years . <hl> During infection , a viral surface protein causes host cells to fuse and form multinucleated giant cells called syncytia . <hl> There are no specific antiviral therapies or vaccines available for viral pneumonia . In adults , these infections are self-limiting , resemble the common cold , and tend to resolve uneventfully within 1 or 2 weeks . Infections in infants , however , can be life-threatening . RSV is highly contagious and can be spread through respiratory droplets from coughing and sneezing . RSV can also survive for a long time on environmental surfaces and , thus , be transmitted indirectly via fomites .", "hl_sentences": "During infection , a viral surface protein causes host cells to fuse and form multinucleated giant cells called syncytia .", "question": { "cloze_format": "The term that refers to multinucleated cells that form when many host cells fuse together during infections is ___.", "normal_format": "What term refers to multinucleated cells that form when many host cells fuse together during infections?", "question_choices": [ "Ghon elements", "Reye syndrome", "Koplik’s spots", "syncytia" ], "question_id": "fs-id1167663636729", "question_text": "What term refers to multinucleated cells that form when many host cells fuse together during infections?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 1, "ans_text": "B" }, "bloom": null, "hl_context": "<hl> Measles , rubella ( German measles ) , and chickenpox are three important viral diseases often associated with skin rashes . <hl> However , their symptoms are systemic , and because their portal of entry is the respiratory tract , they can be considered respiratory infections . <hl> Severe acute respiratory syndrome ( SARS ) and Middle East respiratory syndrome ( MERS ) are two acute respiratory infections caused by coronavirus es . <hl> In both cases , these are thought to be zoonotic infections . Bats and civet cats are thought to have been the reservoirs for SARS ; camels seem to be the reservoir for MERS . The common cold is a generic term for a variety of mild viral infections of the nasal cavity . <hl> More than 200 different viruses are known to cause the common cold . <hl> <hl> The most common groups of cold viruses include rhinovirus es , coronavirus es , and adenovirus es . <hl> These infections are widely disseminated in the human population and are transmitted through direct contact and droplet transmission . Coughing and sneezing efficiently produce infectious aerosols , and rhinoviruses are known to persist on environmental surfaces for up to a week . 17 17 AG L ’ Huillier et al . “ Survival of Rhinoviruses on Human Fingers . ” Clinical Microbiology and Infection 21 , no . 4 ( 2015 ): 381 – 385 .", "hl_sentences": "Measles , rubella ( German measles ) , and chickenpox are three important viral diseases often associated with skin rashes . Severe acute respiratory syndrome ( SARS ) and Middle East respiratory syndrome ( MERS ) are two acute respiratory infections caused by coronavirus es . More than 200 different viruses are known to cause the common cold . The most common groups of cold viruses include rhinovirus es , coronavirus es , and adenovirus es .", "question": { "cloze_format": "The disease that is not associated with coronavirus infections is (the) ___.", "normal_format": "Which of the following diseases is not associated with coronavirus infections?", "question_choices": [ "Middle East respiratory syndrome", "German measles", "the common cold", "severe acute respiratory syndrome" ], "question_id": "fs-id1167663966614", "question_text": "Which of the following diseases is not associated with coronavirus infections?" }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 2, "ans_text": "C" }, "bloom": null, "hl_context": "<hl> Like other herpesviruses , the varicella-zoster virus can become dormant in nerve cells . <hl> While the pustular vesicles are developing , the virus moves along sensory nerves to the dorsal ganglia in the spinal cord . Once there , the varicella-zoster virus can remain latent for decades . These dormant viruses may be reactivated later in life by a variety of stimuli , including stress , aging , and immunosuppression . Once reactivated , the virus moves along sensory nerves to the skin of the face or trunk . <hl> This results in the production of the painful lesions in a condition known as shingles ( Figure 22.21 ) . <hl> These symptoms generally last for 2 – 6 weeks , and may recur more than once . Postherpetic neuralgia , pain signals sent from damaged nerves long after the other symptoms have subsided , is also possible . In addition , the virus can spread to other organs in immunocompromised individuals . A person with shingles lesions can transmit the virus to a nonimmune contact , and the newly infected individual would develop chickenpox as the primary infection . Shingles cannot be transmitted from one person to another .", "hl_sentences": "Like other herpesviruses , the varicella-zoster virus can become dormant in nerve cells . This results in the production of the painful lesions in a condition known as shingles ( Figure 22.21 ) .", "question": { "cloze_format": "The virus that is responsible for causing shingles is the ___.", "normal_format": "Which of these viruses is responsible for causing shingles?", "question_choices": [ "rubella virus", "measles virus", "varicella-zoster virus", "variola major virus" ], "question_id": "fs-id1167663987537", "question_text": "Which of these viruses is responsible for causing shingles?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 1, "ans_text": "B" }, "bloom": null, "hl_context": "<hl> Infection by the dimorphic fungus Coccidioides immitis causes coccidioidomycosis . <hl> <hl> Because the microbe is endemic to the San Joaquin Valley of California , the disease is sometimes referred to as Valley fever . <hl> A related species that causes similar infections is found in semi-arid and arid regions of the southwestern United States , Mexico , and Central and South America . 36 36 DR Hospenthal . “ Coccioidomycosis . ” Medscape . 2015 . http://emedicine.medscape.com/article/215978-overview . Accessed July 7 , 2016 .", "hl_sentences": "Infection by the dimorphic fungus Coccidioides immitis causes coccidioidomycosis . Because the microbe is endemic to the San Joaquin Valley of California , the disease is sometimes referred to as Valley fever .", "question": { "cloze_format": "The infection that is also referred to as Valley fever is ___.", "normal_format": "Which of these infections is also referred to as Valley fever?", "question_choices": [ "histoplasmosis", "coccidioidomycosis", "blastomycosis", "aspergillosis" ], "question_id": "fs-id1167661485741", "question_text": "Which of these infections is also referred to as Valley fever?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 3, "ans_text": "D" }, "bloom": null, "hl_context": "<hl> Blastomycosis is a rare disease caused by another dimorphic fungus , Blastomyces dermatitidis . <hl> Like Histoplasma and Coccidioides , Blastomyces uses the soil as a reservoir , and fungal spores can be inhaled from disturbed soil . The pulmonary form of blastomycosis generally causes mild flu-like symptoms and is self-limiting . It can , however , become disseminated in immunocompromised people , leading to chronic cutaneous disease with subcutaneous lesions on the face and hands ( Figure 22.25 ) . These skin lesions eventually become crusty and discolored and can result in deforming scars . Systemic blastomycosis is rare , but if left untreated , it is always fatal . <hl> Infection by the dimorphic fungus Coccidioides immitis causes coccidioidomycosis . <hl> Because the microbe is endemic to the San Joaquin Valley of California , the disease is sometimes referred to as Valley fever . A related species that causes similar infections is found in semi-arid and arid regions of the southwestern United States , Mexico , and Central and South America . 36 36 DR Hospenthal . “ Coccioidomycosis . ” Medscape . 2015 . http://emedicine.medscape.com/article/215978-overview . Accessed July 7 , 2016 . <hl> Histoplasmosis is a fungal disease of the respiratory system and most commonly occurs in the Mississippi Valley of the United States and in parts of Central and South America , Africa , Asia , and Australia . <hl> <hl> The causative agent , Histoplasma capsulatum , is a dimorphic fungus . <hl> This microbe grows as a filamentous mold in the environment but occurs as a budding yeast during human infections . The primary reservoir for this pathogen is soil , particularly in locations rich in bat or bird feces .", "hl_sentences": "Blastomycosis is a rare disease caused by another dimorphic fungus , Blastomyces dermatitidis . Infection by the dimorphic fungus Coccidioides immitis causes coccidioidomycosis . Histoplasmosis is a fungal disease of the respiratory system and most commonly occurs in the Mississippi Valley of the United States and in parts of Central and South America , Africa , Asia , and Australia . The causative agent , Histoplasma capsulatum , is a dimorphic fungus .", "question": { "cloze_format": "___ is not caused by a dimorphic fungus.", "normal_format": "Which of the following is not caused by a dimorphic fungus?", "question_choices": [ "histoplasmosis", "coccidioidomycosis", "blastomycosis", "aspergillosis" ], "question_id": "fs-id1167663634394", "question_text": "Which of the following is not caused by a dimorphic fungus?" }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 0, "ans_text": "A" }, "bloom": null, "hl_context": "<hl> A variety of fungi in the order Mucorales cause mucormycosis , a rare fungal disease . <hl> <hl> These include bread molds , like Rhizopus and Mucor ; the most commonly associated species is Rhizopus arrhizus ( oryzae ) ( see Figure 5.28 ) . <hl> These fungi can colonize many different tissues in immunocompromised patients , but often infect the skin , sinuses , or the lungs .", "hl_sentences": "A variety of fungi in the order Mucorales cause mucormycosis , a rare fungal disease . These include bread molds , like Rhizopus and Mucor ; the most commonly associated species is Rhizopus arrhizus ( oryzae ) ( see Figure 5.28 ) .", "question": { "cloze_format": "___ is caused by infections by bread molds.", "normal_format": "Which of the following is caused by infections by bread molds?", "question_choices": [ "mucormycosis", "coccidioidomycosis", "cryptococcosis", "Pneumocystis pneumonia" ], "question_id": "fs-id1167661323560", "question_text": "Which of the following is caused by infections by bread molds?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 2, "ans_text": "C" }, "bloom": null, "hl_context": "<hl> Histoplasmosis is a fungal disease of the respiratory system and most commonly occurs in the Mississippi Valley of the United States and in parts of Central and South America , Africa , Asia , and Australia . <hl> The causative agent , Histoplasma capsulatum , is a dimorphic fungus . This microbe grows as a filamentous mold in the environment but occurs as a budding yeast during human infections . The primary reservoir for this pathogen is soil , particularly in locations rich in bat or bird feces .", "hl_sentences": "Histoplasmosis is a fungal disease of the respiratory system and most commonly occurs in the Mississippi Valley of the United States and in parts of Central and South America , Africa , Asia , and Australia .", "question": { "cloze_format": "In the United States, most histoplasmosis cases occur ___.", "normal_format": "Where do most histoplasmosis cases occur in the United States?", "question_choices": [ "in the Pacific northwest.", "in the desert southwest.", "in the Mississippi river valley.", "in Colorado river valley." ], "question_id": "fs-id1167663955713", "question_text": "In the United States, most histoplasmosis cases occur" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 3, "ans_text": "D" }, "bloom": null, "hl_context": "Laboratory diagnosis typically requires chest radiographs and a microscopic examination of tissue and respiratory fluid samples . <hl> Serological tests are available to identify Aspergillus antigens . <hl> <hl> In addition , a skin test can be performed to determine if the patient has been exposed to the fungus . <hl> <hl> This test is similar to the Mantoux tuberculin skin test used for tuberculosis . <hl> <hl> Aspergillosis is treated with intravenous antifungal agents , including itraconazole and voriconazole . <hl> Allergic symptoms can be managed with corticosteroids because these drugs suppress the immune system and reduce inflammation . However , in disseminated infections , corticosteroids must be discontinued to allow a protective immune response to occur .", "hl_sentences": "Serological tests are available to identify Aspergillus antigens . In addition , a skin test can be performed to determine if the patient has been exposed to the fungus . This test is similar to the Mantoux tuberculin skin test used for tuberculosis . Aspergillosis is treated with intravenous antifungal agents , including itraconazole and voriconazole .", "question": { "cloze_format": "The infection that can be diagnosed using a skin test similar to the tuberculin test is ___.", "normal_format": "Which of the following infections can be diagnosed using a skin test similar to the tuberculin test?", "question_choices": [ "histoplasmosis", "cryptococcosis", "blastomycosis", "aspergillosis" ], "question_id": "fs-id1167663991434", "question_text": "Which of the following infections can be diagnosed using a skin test similar to the tuberculin test?" }, "references_are_paraphrase": null } ]
22
22.1 Anatomy and Normal Microbiota of the Respiratory Tract Learning Objectives Describe the major anatomical features of the upper and lower respiratory tract Describe the normal microbiota of the upper and lower respiratory tracts Explain how microorganisms overcome defenses of upper and lower respiratory-tract membranes to cause infection Explain how microbes and the respiratory system interact and modify each other in healthy individuals and during an infection Clinical Focus Part 1 John, a 65-year-old man with asthma and type 2 diabetes, works as a sales associate at a local home improvement store. Recently, he began to feel quite ill and made an appointment with his family physician. At the clinic, John reported experiencing headache, chest pain, coughing, and shortness of breath. Over the past day, he had also experienced some nausea and diarrhea. A nurse took his temperature and found that he was running a fever of 40 °C (104 °F). John suggested that he must have a case of influenza (flu), and regretted that he had put off getting his flu vaccine this year. After listening to John’s breathing through a stethoscope, the physician ordered a chest radiography and collected blood, urine, and sputum samples. Based on this information, what factors may have contributed to John’s illness? Jump to the next Clinical Focus box . The primary function of the respiratory tract is to exchange gases (oxygen and carbon dioxide) for metabolism. However, inhalation and exhalation (particularly when forceful) can also serve as a vehicle of transmission for pathogens between individuals. Anatomy of the Upper Respiratory System The respiratory system can be conceptually divided into upper and lower regions at the point of the epiglottis , the structure that seals off the lower respiratory system from the pharynx during swallowing ( Figure 22.2 ). The upper respiratory system is in direct contact with the external environment. The nares (or nostrils) are the external openings of the nose that lead back into the nasal cavity , a large air-filled space behind the nares. These anatomical sites constitute the primary opening and first section of the respiratory tract, respectively. The nasal cavity is lined with hairs that trap large particles, like dust and pollen, and prevent their access to deeper tissues. The nasal cavity is also lined with a mucous membrane and Bowman’s glands that produce mucus to help trap particles and microorganisms for removal. The nasal cavity is connected to several other air-filled spaces. The sinuses, a set of four, paired small cavities in the skull, communicate with the nasal cavity through a series of small openings. The nasopharynx is part of the upper throat extending from the posterior nasal cavity. The nasopharynx carries air inhaled through the nose. The middle ear is connected to the nasopharynx through the eustachian tube . The middle ear is separated from the outer ear by the tympanic membrane , or ear drum. And finally, the lacrimal glands drain to the nasal cavity through the nasolacrimal ducts (tear ducts). The open connections between these sites allow microorganisms to move from the nasal cavity to the sinuses, middle ears (and back), and down into the lower respiratory tract from the nasopharynx. The oral cavity is a secondary opening for the respiratory tract. The oral and nasal cavities connect through the fauces to the pharynx, or throat. The pharynx can be divided into three regions: the nasopharynx, the oropharynx , and the laryngopharynx . Air inhaled through the mouth does not pass through the nasopharynx; it proceeds first through the oropharynx and then through the laryngopharynx. The palatine tonsils , which consist of lymphoid tissue, are located within the oropharynx. The laryngopharynx, the last portion of the pharynx, connects to the larynx , which contains the vocal fold ( Figure 22.2 ). Check Your Understanding Identify the sequence of anatomical structures through which microbes would pass on their way from the nares to the larynx. What two anatomical points do the eustachian tubes connect? Anatomy of the Lower Respiratory System The lower respiratory system begins below the epiglottis in the larynx or voice box ( Figure 22.3 ). The trachea , or windpipe, is a cartilaginous tube extending from the larynx that provides an unobstructed path for air to reach the lungs. The trachea bifurcates into the left and right bronchi as it reaches the lungs. These paths branch repeatedly to form smaller and more extensive networks of tubes, the bronchiole s. The terminal bronchioles formed in this tree-like network end in cul-de-sacs called the alveoli . These structures are surrounded by capillary networks and are the site of gas exchange in the respiratory system. Human lungs contain on the order of 400,000,000 alveoli. The outer surface of the lungs is protected with a double-layered pleural membrane. This structure protects the lungs and provides lubrication to permit the lungs to move easily during respiration. Defenses of the Respiratory System The inner lining of the respiratory system consists of mucous membrane s ( Figure 22.4 ) and is protected by multiple immune defenses. The goblet cell s within the respiratory epithelium secrete a layer of sticky mucus. The viscosity and acidity of this secretion inhibits microbial attachment to the underlying cells. In addition, the respiratory tract contains ciliated epithelial cells. The beating cilia dislodge and propel the mucus, and any trapped microbes, upward to the epiglottis, where they will be swallowed. Elimination of microbes in this manner is referred to as the mucociliary escalator effect and is an important mechanism that prevents inhaled microorganisms from migrating further into the lower respiratory tract. The upper respiratory system is under constant surveillance by mucosa-associated lymphoid tissue (MALT) , including the adenoids and tonsils. Other mucosal defenses include secreted antibodies (IgA), lysozyme, surfactant, and antimicrobial peptides called defensins . Meanwhile, the lower respiratory tract is protected by alveolar macrophage s. These phagocytes efficiently kill any microbes that manage to evade the other defenses. The combined action of these factors renders the lower respiratory tract nearly devoid of colonized microbes. Check Your Understanding Identify the sequence of anatomical structures through which microbes would pass on their way from the larynx to the alveoli. Name some defenses of the respiratory system that protect against microbial infection. Normal Microbiota of the Respiratory System The upper respiratory tract contains an abundant and diverse microbiota . The nasal passages and sinuses are primarily colonized by members of the Firmicutes , Actinobacteria , and Proteobacteria . The most common bacteria identified include Staphylococcus epidermidis , viridans group streptococci (VGS), Corynebacterium spp. (diphtheroids), Propionibacterium spp., and Haemophilus spp. The oropharynx includes many of the same isolates as the nose and sinuses, with the addition of variable numbers of bacteria like species of Prevotella , Fusobacterium , Moraxella , and Eikenella , as well as some Candida fungal isolates. In addition, many healthy humans asymptomatically carry potential pathogens in the upper respiratory tract. As much as 20% of the population carry Staphylococcus aureus in their nostrils. 2 The pharynx, too, can be colonized with pathogenic strains of Streptococcus , Haemophilus , and Neisseria . 2 J. Kluytmans et al. “Nasal Carriage of Staphylococcus aureus : Epidemiology, Underlying Mechanisms, and Associated Risks.” Clinical Microbiology Reviews 10 no. 3 (1997):505–520. The lower respiratory tract, by contrast, is scantily populated with microbes. Of the organisms identified in the lower respiratory tract, species of Pseudomonas , Streptococcus , Prevotella , Fusobacterium , and Veillonella are the most common. It is not clear at this time if these small populations of bacteria constitute a normal microbiota or if they are transients. Many members of the respiratory system’s normal microbiota are opportunistic pathogens. To proliferate and cause host damage, they first must overcome the immune defenses of respiratory tissues. Many mucosal pathogens produce virulence factors such as adhesin s that mediate attachment to host epithelial cells, or polysaccharide capsules that allow microbes to evade phagocytosis. The endotoxin s of gram-negative bacteria can stimulate a strong inflammatory response that damages respiratory cells. Other pathogens produce exotoxin s, and still others have the ability to survive within the host cells. Once an infection of the respiratory tract is established, it tends to impair the mucociliary escalator , limiting the body’s ability to expel the invading microbes, thus making it easier for pathogens to multiply and spread. Vaccines have been developed for many of the most serious bacterial and viral pathogens. Several of the most important respiratory pathogens and their vaccines, if available, are summarized in Table 22.1 . Components of these vaccines will be explained later in the chapter. Some Important Respiratory Diseases and Vaccines Disease Pathogen Available Vaccine(s) 3 3 Full names of vaccines listed in table: Haemophilus influenzae type B (Hib); Diphtheria, tetanus, and acellular pertussis (DtaP); tetanus, diphtheria, and acellular pertussis (Tdap); diphtheria and tetanus (DT); tetanus and diphtheria (Td); diphtheria, pertussis, and tetanus (DTP); Bacillus Calmette-Guérin; Measles, mumps, rubella (MMR) Chickenpox/shingles Varicella-zoster virus Varicella (chickenpox) vaccine, herpes zoster (shingles) vaccine Common cold Rhinovirus None Diphtheria Corynebacterium diphtheriae DtaP, Tdap, DT,Td, DTP Epiglottitis, otitis media Haemophilus influenzae Hib Influenza Influenza viruses Inactivated, FluMist Measles Measles virus MMR Pertussis Bordetella pertussis DTaP, Tdap Pneumonia Streptococcus pneumoniae Pneumococcal conjugate vaccine (PCV13), pneumococcal polysaccharide vaccine (PPSV23) Rubella (German measles) Rubella virus MMR Severe acute respiratory syndrome (SARS) SARS-associated coronavirus (SARS-CoV) None Tuberculosis Mycobacterium tuberculosis BCG Table 22.1 Check Your Understanding What are some pathogenic bacteria that are part of the normal microbiota of the respiratory tract? What virulence factors are used by pathogens to overcome the immune protection of the respiratory tract? Signs and Symptoms of Respiratory Infection Microbial diseases of the respiratory system typically result in an acute inflammatory response. These infections can be grouped by the location affected and have names ending in “itis”, which literally means inflammation of . For instance, rhinitis is an inflammation of the nasal cavities, often characteristic of the common cold. Rhinitis may also be associated with hay fever allergies or other irritants. Inflammation of the sinuses is called sinusitis inflammation of the ear is called otitis . Otitis media is an inflammation of the middle ear. A variety of microbes can cause pharyngitis , commonly known as a sore throat. An inflammation of the larynx is called laryngitis . The resulting inflammation may interfere with vocal cord function, causing voice loss. When tonsils are inflamed, it is called tonsillitis . Chronic cases of tonsillitis may be treated surgically with tonsillectomy. More rarely, the epiglottis can be infected, a condition called epiglottitis . In the lower respiratory system, the inflammation of the bronchial tubes results in bronchitis . Most serious of all is pneumonia , in which the alveoli in the lungs are infected and become inflamed. Pus and edema accumulate and fill the alveoli with fluids (called consolidations). This reduces the lungs’ ability to exchange gases and often results in a productive cough expelling phlegm and mucus. Cases of pneumonia can range from mild to life-threatening, and remain an important cause of mortality in the very young and very old. Check Your Understanding Describe the typical symptoms of rhinitis, sinusitis, pharyngitis, and laryngitis. Case in Point Smoking-Associated Pneumonia Camila is a 22-year-old student who has been a chronic smoker for 5 years. Recently, she developed a persistent cough that has not responded to over-the-counter treatments. Her doctor ordered a chest radiograph to investigate. The radiological results were consistent with pneumonia. In addition, Streptococcus pneumoniae was isolated from Camila’s sputum. Smokers are at a greater risk of developing pneumonia than the general population. Several components of tobacco smoke have been demonstrated to impair the lungs’ immune defenses. These effects include disrupting the function of the ciliated epithelial cells, inhibiting phagocytosis, and blocking the action of antimicrobial peptides. Together, these lead to a dysfunction of the mucociliary escalator effect. The organisms trapped in the mucus are therefore able to colonize the lungs and cause infections rather than being expelled or swallowed. 22.2 Bacterial Infections of the Respiratory Tract Learning Objectives Identify the most common bacteria that can cause infections of the upper and lower respiratory tract Compare the major characteristics of specific bacterial diseases of the respiratory tract The respiratory tract can be infected by a variety of bacteria, both gram positive and gram negative. Although the diseases that they cause may range from mild to severe, in most cases, the microbes remain localized within the respiratory system. Fortunately, most of these infections also respond well to antibiotic therapy. Streptococcal Infections A common upper respiratory infection, streptococcal pharyngitis ( strep throat ) is caused by Streptococcus pyogenes . This gram-positive bacterium appears as chains of cocci, as seen in Figure 22.5 . Rebecca Lancefield serologically classified streptococci in the 1930s using carbohydrate antigens from the bacterial cell walls. S. pyogenes is the sole member of the Lancefield group A streptococci and is often referred to as GAS, or group A strep. Similar to streptococcal infections of the skin, the mucosal membranes of the pharynx are damaged by the release of a variety of exoenzymes and exotoxins by this extracellular pathogen. Many strains of S. pyogenes can degrade connective tissues by using hyaluronidase , collagenase and streptokinase . Streptokinase activates plasmin, which leads to degradation of fibrin and, in turn, dissolution of blood clots, which assists in the spread of the pathogen. Released toxins include streptolysin s that can destroy red and white blood cells. The classic signs of streptococcal pharyngitis are a fever higher than 38 °C (100.4 °F); intense pharyngeal pain; erythema associated with pharyngeal inflammation; and swollen, dark-red palatine tonsils, often dotted with patches of pus; and petechiae (microcapillary hemorrhages) on the soft or hard palate (roof of the mouth) ( Figure 22.6 ). The submandibular lymph nodes beneath the angle of the jaw are also often swollen during strep throat. Some strains of group A streptococci produce erythrogenic toxin . This exotoxin is encoded by a temperate bacteriophage (bacterial virus) and is an example of phage conversion (see The Viral Life Cycle ). The toxin attacks the plasma membranes of capillary endothelial cells and leads to scarlet fever (or scarlatina), a disseminated fine red rash on the skin, and strawberry tongue , a red rash on the tongue ( Figure 22.6 ). Severe cases may even lead to streptococcal toxic shock syndrome (STSS) , which results from massive superantigen production that leads to septic shock and death. S. pyogenes can be easily spread by direct contact or droplet transmission through coughing and sneezing. The disease can be diagnosed quickly using a rapid enzyme immunoassay for the group A antigen. However, due to a significant rate of false-negative results (up to 30% 4 ), culture identification is still the gold standard to confirm pharyngitis due to S. pyogenes . S. pyogenes can be identified as a catalase-negative, beta hemolytic bacterium that is susceptible to 0.04 units of bacitracin. Antibiotic resistance is limited for this bacterium, so most β-lactams remain effective; oral amoxicillin and intramuscular penicillin G are those most commonly prescribed. 4 WL Lean et al. “Rapid Diagnostic Tests for Group A Streptococcal Pharyngitis: A Meta-Analysis.” Pediatrics 134, no. 4 (2014):771–781. Sequelae of S. pyogenes Infections One reason strep throat infections are aggressively treated with antibiotics is because they can lead to serious sequelae , later clinical consequences of a primary infection. It is estimated that 1%–3% of untreated S. pyogenes infections can be followed by nonsuppurative (without the production of pus) sequelae that develop 1–3 weeks after the acute infection has resolved. Two such sequelae are acute rheumatic fever and acute glomerulonephritis . Acute rheumatic fever can follow pharyngitis caused by specific rheumatogenic strains of S. pyogenes (strains 1, 3, 5, 6, and 18). Although the exact mechanism responsible for this sequela remains unclear, molecular mimicry between the M protein of rheumatogenic strains of S. pyogenes and heart tissue is thought to initiate the autoimmune attack. The most serious and lethal clinical manifestation of rheumatic fever is damage to and inflammation of the heart ( carditis ). Acute glomerulonephritis also results from an immune response to streptococcal antigens following pharyngitis and cutaneous infections. Acute glomerulonephritis develops within 6–10 days after pharyngitis, but can take up to 21 days after a cutaneous infection. Similar to acute rheumatic fever, there are strong associations between specific nephritogenic strains of S. pyogenes and acute glomerulonephritis, and evidence suggests a role for antigen mimicry and autoimmunity. However, the primary mechanism of acute glomerulonephritis appears to be the formation of immune complexes between S. pyogenes antigens and antibodies, and their deposition between endothelial cells of the glomeruli of kidney. Inflammatory response against the immune complexes leads to damage and inflammation of the glomeruli (glomerulonephritis). Check Your Understanding What are the symptoms of strep throat? What is erythrogenic toxin and what effect does it have? What are the causes of rheumatic fever and acute glomerulonephritis? Acute Otitis Media An infection of the middle ear is called acute otitis media ( AOM ), but often it is simply referred to as an earache. The condition is most common between ages 3 months and 3 years. In the United States, AOM is the second-leading cause of visits to pediatricians by children younger than age 5 years, and it is the leading indication for antibiotic prescription. 5 5 G. Worrall. “Acute Otitis Media.” Canadian Family Physician 53 no. 12 (2007):2147–2148. AOM is characterized by the formation and accumulation of pus in the middle ear. Unable to drain, the pus builds up, resulting in moderate to severe bulging of the tympanic membrane and otalgia (ear pain). Inflammation resulting from the infection leads to swelling of the eustachian tubes, and may also lead to fever, nausea, vomiting, and diarrhea, particularly in infants. Infants and toddlers who cannot yet speak may exhibit nonverbal signs suggesting AOM, such as holding, tugging, or rubbing of the ear, as well as uncharacteristic crying or distress in response to the pain. AOM can be caused by a variety of bacteria. Among neonates, S. pneumoniae is the most common cause of AOM, but Escherichia coli , Enterococcus spp., and group B Streptococcus species can also be involved. In older infants and children younger than 14 years old, the most common bacterial causes are S. pneumoniae , Haemophilus influenzae , or Moraxella catarrhalis . Among S. pneumoniae infections , encapsulated strains are frequent causes of AOM. By contrast, the strains of H. influenzae and M. cattarhalis that are responsible for AOM do not possess a capsule. Rather than direct tissue damage by these pathogens, bacterial components such as lipopolysaccharide (LPS) in gram-negative pathogens induce an inflammatory response that causes swelling, pus, and tissue damage within the middle ear ( Figure 22.7 ). Any blockage of the eustachian tubes, with or without infection, can cause fluid to become trapped and accumulate in the middle ear. This is referred to as otitis media with effusion (OME) . The accumulated fluid offers an excellent reservoir for microbial growth and, consequently, secondary bacterial infections often ensue. This can lead to recurring and chronic earaches, which are especially common in young children. The higher incidence in children can be attributed to many factors. Children have more upper respiratory infections, in general, and their eustachian tubes are also shorter and drain at a shallower angle. Young children also tend to spend more time lying down than adults, which facilitates drainage from the nasopharynx through the eustachian tube and into the middle ear. Bottle feeding while lying down enhances this risk because the sucking action on the bottle causes negative pressure to build up within the eustachian tube, promoting the movement of fluid and bacteria from the nasopharynx. Diagnosis is typically made based on clinical signs and symptoms, without laboratory testing to determine the specific causative agent. Antibiotics are frequently prescribed for the treatment of AOM. High-dose amoxicillin is the first-line drug, but with increasing resistance concerns, macrolides and cephalosporin s may also be used. The pneumococcal conjugate vaccine (PCV13) contains serotypes that are important causes of AOM, and vaccination has been shown to decrease the incidence of AOM. Vaccination against influenza has also been shown to decrease the risk for AOM, likely because viral infections like influenza predispose patients to secondary infections with S. pneumoniae . Although there is a conjugate vaccine available for the invasive serotype B of H. influenzae , this vaccine does not impact the incidence of H. influenzae AOM. Because unencapsulated strains of H. influenzae and M. catarrhalis are involved in AOM, vaccines against bacterial cellular factors other than capsules will need to be developed. Bacterial Rhinosinusitis The microbial community of the nasopharynx is extremely diverse and harbors many opportunistic pathogens, so it is perhaps not surprising that infections leading to rhinitis and sinusitis have many possible causes. These conditions often occur as secondary infections after a viral infection, which effectively compromises the immune defenses and allows the opportunistic bacteria to establish themselves. Bacterial sinusitis involves infection and inflammation within the paranasal sinuses. Because bacterial sinusitis rarely occurs without rhinitis, the preferred term is rhinosinusitis . The most common causes of bacterial rhinosinusitis are similar to those for AOM, including S. pneumoniae , H. influenzae , and M. catarrhalis . Check Your Understanding What are the usual causative agents of acute otitis media? What factors facilitate acute otitis media with effusion in young children? What factor often triggers bacterial rhinosinusitis? Diphtheria The causative agent of diphtheria , Corynebacterium diphtheriae , is a club-shaped, gram-positive rod that belongs to the phylum Actinobacteria . Diphtheroids are common members of the normal nasopharyngeal microbiota. However, some strains of C. diphtheriae become pathogenic because of the presence of a temperate bacteriophage-encoded protein—the diphtheria toxin . Diphtheria is typically a respiratory infection of the oropharynx but can also cause impetigo-like lesions on the skin. Although the disease can affect people of all ages, it tends to be most severe in those younger than 5 years or older than 40 years. Like strep throat, diphtheria is commonly transmitted in the droplets and aerosols produced by coughing. After colonizing the throat, the bacterium remains in the oral cavity and begins producing the diphtheria toxin. This protein is an A-B toxin that blocks host-cell protein synthesis by inactivating elongation factor (EF)-2 (see Virulence Factors of Bacterial and Viral Pathogens ). The toxin’s action leads to the death of the host cells and an inflammatory response. An accumulation of grayish exudate consisting of dead host cells, pus, red blood cells, fibrin, and infectious bacteria results in the formation of a pseudomembrane . The pseudomembrane can cover mucous membranes of the nasal cavity, tonsils, pharynx, and larynx ( Figure 22.8 ). This is a classic sign of diphtheria. As the disease progresses, the pseudomembrane can enlarge to obstruct the fauces of the pharynx or trachea and can lead to suffocation and death. Sometimes, intubation , the placement of a breathing tube in the trachea, is required in advanced infections. If the diphtheria toxin spreads throughout the body, it can damage other tissues as well. This can include myocarditis (heart damage) and nerve damage that may impair breathing. The presumptive diagnosis of diphtheria is primarily based on the clinical symptoms (i.e., the pseudomembrane) and vaccination history, and is typically confirmed by identifying bacterial cultures obtained from throat swabs. The diphtheria toxin itself can be directly detected in vitro using polymerase chain reaction (PCR)-based, direct detection systems for the diphtheria tox gene, and immunological techniques like radial immunodiffusion or Elek’s immunodiffusion test. Broad-spectrum antibiotics like penicillin and erythromycin tend to effectively control C. diphtheriae infections. Regrettably, they have no effect against preformed toxins. If toxin production has already occurred in the patient, antitoxins (preformed antibodies against the toxin) are administered. Although this is effective in neutralizing the toxin, the antitoxins may lead to serum sickness because they are produced in horses (see Hypersensitivities ). Widespread vaccination efforts have reduced the occurrence of diphtheria worldwide. There are currently four combination toxoid vaccines available that provide protection against diphtheria and other diseases: DTaP, Tdap, DT, and Td. In all cases, the letters “d,” “t,” and “p” stand for diphtheria, tetanus, and pertussis, respectively; the “a” stands for acellular. If capitalized, the letters indicate a full-strength dose; lowercase letters indicate reduced dosages. According to current recommendations, children should receive five doses of the DTaP vaccine in their youth and a Td booster every 10 years. Children with adverse reactions to the pertussis vaccine may be given the DT vaccine in place of the DTaP. Check Your Understanding What effect does diphtheria toxin have? What is the pseudomembrane composed of? Bacterial Pneumonia Pneumonia is a general term for infections of the lungs that lead to inflammation and accumulation of fluids and white blood cells in the alveoli. Pneumonia can be caused by bacteria, viruses, fungi, and other organisms, although the vast majority of pneumonias are bacterial in origin. Bacterial pneumonia is a prevalent, potentially serious infection; it caused more 50,000 deaths in the United States in 2014. 6 As the alveoli fill with fluids and white blood cells (consolidation), air exchange becomes impaired and patients experience respiratory distress ( Figure 22.9 ). In addition, pneumonia can lead to pleurisy , an infection of the pleural membrane surrounding the lungs, which can make breathing very painful. Although many different bacteria can cause pneumonia under the right circumstances, three bacterial species cause most clinical cases: Streptococcus pneumoniae , H . influenzae , and Mycoplasma pneumoniae . In addition to these, we will also examine some of the less common causes of pneumonia. 6 KD Kochanek et al. “Deaths: Final Data for 2014.” National Vital Statistics Reports 65 no 4 (2016). Pneumococcal Pneumonia The most common cause of community-acquired bacterial pneumonia is Streptococcus pneumoniae . This gram-positive, alpha hemolytic streptococcus is commonly found as part of the normal microbiota of the human respiratory tract. The cells tend to be somewhat lancet-shaped and typically appear as pairs ( Figure 22.10 ). The pneumococci initially colonize the bronchioles of the lungs. Eventually, the infection spreads to the alveoli, where the microbe’s polysaccharide capsule interferes with phagocytic clearance. Other virulence factors include autolysin s like Lyt A, which degrade the microbial cell wall, resulting in cell lysis and the release of cytoplasmic virulence factors. One of these factors, pneumolysin O , is important in disease progression; this pore-forming protein damages host cells, promotes bacterial adherence, and enhances pro-inflammatory cytokine production. The resulting inflammatory response causes the alveoli to fill with exudate rich in neutrophils and red blood cells. As a consequence, infected individuals develop a productive cough with bloody sputum. Pneumococci can be presumptively identified by their distinctive gram-positive, lancet-shaped cell morphology and diplococcal arrangement. In blood agar cultures, the organism demonstrates alpha hemolytic colonies that are autolytic after 24 to 48 hours. In addition, S. pneumoniae is extremely sensitive to optochin and colonies are rapidly destroyed by the addition of 10% solution of sodium deoxycholate. All clinical pneumococcal isolates are serotyped using the quellung reaction with typing antisera produced by the CDC. Positive quellung reactions are considered definitive identification of pneumococci. Antibiotics remain the mainstay treatment for pneumococci. β-Lactams like penicillin are the first-line drugs, but resistance to β-lactams is a growing problem. When β-lactam resistance is a concern, macrolides and fluoroquinolones may be prescribed. However, S. pneumoniae resistance to macrolides and fluoroquinolones is increasing as well, limiting the therapeutic options for some infections. There are currently two pneumococcal vaccines available: pneumococcal conjugate vaccine (PCV13) and pneumococcal polysaccharide vaccine (PPSV23). These are generally given to the most vulnerable populations of individuals: children younger than 2 years and adults older than 65 years. Haemophilus Pneumonia Encapsulated strains of Haemophilus influenzae are known for causing meningitis, but nonencapsulated strains are important causes of pneumonia. This small, gram-negative coccobacillus is found in the pharynx of the majority of healthy children; however, Haemophilus pneumonia is primarily seen in the elderly. Like other pathogens that cause pneumonia, H. influenzae is spread by droplets and aerosols produced by coughing. A fastidious organism, H. influenzae will only grow on media with available factor X (hemin) and factor V (NAD), like chocolate agar ( Figure 22.11 ). Serotyping must be performed to confirm identity of H. influenzae isolates. Infections of the alveoli by H. influenzae result in inflammation and accumulation of fluids. Increasing resistance to β-lactams , macrolides , and tetracyclines presents challenges for the treatment of Haemophilus pneumonia. Resistance to the fluoroquinolones is rare among isolates of H. influenzae but has been observed. As discussed for AOM, a vaccine directed against nonencapsulated H. influenzae, if developed, would provide protection against pneumonia caused by this pathogen. Case in Point Why Me? Tracy is a 6-year old who developed a serious cough that would not seem to go away. After 2 weeks, her parents became concerned and took her to the pediatrician, who suspected a case of bacterial pneumonia. Tests confirmed that the cause was Haemophilus influenzae . Fortunately, Tracy responded well to antibiotic treatment and eventually made a full recovery. Because there had been several other cases of bacterial pneumonia at Tracy’s elementary school, local health officials urged parents to have their children screened. Of the children who were screened, it was discovered that greater than 50% carried H. influenzae in their nasal cavities, yet all but two of them were asymptomatic. Why is it that some individuals become seriously ill from bacterial infections that seem to have little or no effect on others? The pathogenicity of an organism—its ability to cause host damage—is not solely a property of the microorganism. Rather, it is the product of a complex relationship between the microbe’s virulence factors and the immune defenses of the individual. Preexisting conditions and environmental factors such as exposure to secondhand smoke can make some individuals more susceptible to infection by producing conditions favorable to microbial growth or compromising the immune system. In addition, individuals may have genetically determined immune factors that protect them—or not—from particular strains of pathogens. The interactions between these host factors and the pathogenicity factors produced by the microorganism ultimately determine the outcome of the infection. A clearer understanding of these interactions may allow for better identification of at-risk individuals and prophylactic interventions in the future. Mycoplasma Pneumonia (Walking Pneumonia) Primary atypical pneumonia is caused by Mycoplasma pneumoniae . This bacterium is not part of the respiratory tract’s normal microbiota and can cause epidemic disease outbreaks. Also known as walking pneumonia, mycoplasma pneumonia infections are common in crowded environments like college campuses and military bases. It is spread by aerosols formed when coughing or sneezing. The disease is often mild, with a low fever and persistent cough. These bacteria, which do not have cell walls, use a specialized attachment organelle to bind to ciliated cells. In the process, epithelial cells are damaged and the proper function of the cilia is hindered ( Figure 22.12 ). Mycoplasma grow very slowly when cultured. Therefore, penicillin and thallium acetate are added to agar to prevent the overgrowth by faster-growing potential contaminants. Since M. pneumoniae does not have a cell wall, it is resistant to these substances. Without a cell wall, the microbial cells appear pleomorphic. M. pneumoniae infections tend to be self-limiting but may also respond well to macrolide antibiotic therapy. β-lactams, which target cell wall synthesis, are not indicated for treatment of infections with this pathogen. Chlamydial Pneumonias and Psittacosis Chlamydial pneumonia can be caused by three different species of bacteria: Chlamydophila pneumoniae (formerly known as Chlamydia pneumoniae ), Chlamydophila psittaci (formerly known as Chlamydia psittaci ), and Chlamydia trachomatis . All three are obligate intracellular pathogens and cause mild to severe pneumonia and bronchitis. Of the three, Chlamydophila pneumoniae is the most common and is transmitted via respiratory droplets or aerosols. C. psittaci causes psittacosis , a zoonotic disease that primarily affects domesticated birds such as parakeets, turkeys, and ducks, but can be transmitted from birds to humans. Psittacosis is a relatively rare infection and is typically found in people who work with birds. Chlamydia trachomatis, the causative agent of the sexually transmitted disease chlamydia, can cause pneumonia in infants when the infection is passed from mother to baby during birth. Diagnosis of chlamydia by culturing tends to be difficult and slow. Because they are intracellular pathogens, they require multiple passages through tissue culture. Recently, a variety of PCR- and serologically based tests have been developed to enable easier identification of these pathogens. Tetracycline and macrolide antibiotics are typically prescribed for treatment. Health Care-Associated Pneumonia A variety of opportunistic bacteria that do not typically cause respiratory disease in healthy individuals are common causes of health care-associated pneumonia. These include Klebsiella pneumoniae , Staphylococcus aureus , and proteobacteria such as species of Escherichia , Proteus , and Serratia . Patients at risk include the elderly, those who have other preexisting lung conditions, and those who are immunocompromised. In addition, patients receiving supportive therapies such as intubation, antibiotics, and immunomodulatory drugs may also be at risk because these interventions disrupt the mucociliary escalator and other pulmonary defenses. Invasive medical devices such as catheters, medical implants, and ventilators can also introduce opportunistic pneumonia-causing pathogens into the body. 7 7 SM Koenig et al. “Ventilator-Associated Pneumonia: Diagnosis, Treatment, and Prevention.” Clinical Microbiology Reviews 19 no. 4 (2006):637–657. Pneumonia caused by K. pneumoniae is characterized by lung necrosis and “currant jelly sputum,” so named because it consists of clumps of blood, mucus, and debris from the thick polysaccharide capsule produced by the bacterium. K. pneumoniae is often multidrug resistant. Aminoglycoside and cephalosporin are often prescribed but are not always effective. Klebsiella pneumonia is frequently fatal even when treated. Pseudomonas Pneumonia Pseudomonas aeruginosa is another opportunistic pathogen that can cause serious cases of bacterial pneumonia in patients with cystic fibrosis (CF) and hospitalized patients assisted with artificial ventilators. This bacterium is extremely antibiotic resistant and can produce a variety of exotoxins. Ventilator-associated pneumonia with P. aeruginosa is caused by contaminated equipment that causes the pathogen to be aspirated into the lungs. In patients with CF, a genetic defect in the cystic fibrosis transmembrane receptor (CFTR) leads to the accumulation of excess dried mucus in the lungs. This decreases the effectiveness of the defensins and inhibits the mucociliary escalator . P. aeruginosa is known to infect more than half of all patients with CF. It adapts to the conditions in the patient’s lungs and begins to produce alginate, a viscous exopolysaccharide that inhibits the mucociliary escalator. Lung damage from the chronic inflammatory response that ensues is the leading cause of mortality in patients with CF. 8 8 R. Sordé et al. “Management of Refractory Pseudomonas aeruginosa Infection in Cystic Fibrosis.” Infection and Drug Resistance 4 (2011):31–41. Check Your Understanding What three pathogens are responsible for the most prevalent types of bacterial pneumonia? Which cause of pneumonia is most likely to affect young people? In what contexts does Pseudomonas aeruginosa cause pneumonia? Clinical Focus Part 2 John’s chest radiograph revealed an extensive consolidation in the right lung, and his sputum cultures revealed the presence of a gram-negative rod. His physician prescribed a course of the antibiotic clarithromycin. He also ordered the rapid influenza diagnostic tests (RIDTs) for type A and B influenza to rule out a possible underlying viral infection. Despite antibiotic therapy, John’s condition continued to deteriorate, so he was admitted to the hospital. What are some possible causes of pneumonia that would not have responded to the prescribed antibiotic? Jump to the next Clinical Focus box. Go back to the previous Clinical Focus box . Tuberculosis Tuberculosis (TB) is one of the deadliest infectious diseases in human history. Although tuberculosis infection rates in the United States are extremely low, the CDC estimates that about one-third of the world’s population is infected with Mycobacterium tuberculosis , the causal organism of TB, with 9.6 million new TB cases and 1.5 million deaths worldwide in 2014. 9 9 Centers for Disease Control and Prevention. “Tuberculosis (TB). Data and Statistics.” http://www.cdc.gov/tb/statistics/default.htm M. tuberculosis is an acid-fast, high G + C, gram-positive, nonspore-forming rod. Its cell wall is rich in waxy mycolic acids, which make the cells impervious to polar molecules. It also causes these organisms to grow slowly. M. tuberculosis causes a chronic granulomatous disease that can infect any area of the body, although it is typically associated with the lungs. M. tuberculosis is spread by inhalation of respiratory droplets or aerosols from an infected person. The infectious dose of M. tuberculosis is only 10 cells. 10 10 D. Saini et al. “Ultra-Low Dose of Mycobacterium tuberculosis Aerosol Creates Partial Infection in Mice.” Tuberculosis 92 no. 2 (2012):160–165. After inhalation, the bacteria enter the alveoli ( Figure 22.13 ). The cells are phagocytized by macrophages but can survive and multiply within these phagocytes because of the protection by the waxy mycolic acid in their cell walls. If not eliminated by macrophages, the infection can progress, causing an inflammatory response and an accumulation of neutrophils and macrophages in the area. Several weeks or months may pass before an immunological response is mounted by T cells and B cells. Eventually, the lesions in the alveoli become walled off, forming small round lesions called tubercles . Bacteria continue to be released into the center of the tubercles and the chronic immune response results in tissue damage and induction of apoptosis (programmed host-cell death) in a process called liquefaction. This creates a caseous center, or air pocket, where the aerobic M. tuberculosis can grow and multiply. Tubercles may eventually rupture and bacterial cells can invade pulmonary capillaries; from there, bacteria can spread through the bloodstream to other organs, a condition known as miliary tuberculosis . The rupture of tubercles also facilitates transmission of the bacteria to other individuals via droplet aerosols that exit the body in coughs. Because these droplets can be very small and stay aloft for a long time, special precautions are necessary when caring for patients with TB, such as the use of face masks and negative-pressure ventilation and filtering systems. Eventually, most lesions heal to form calcified Ghon complexes . These structures are visible on chest radiographs and are a useful diagnostic feature. But even after the disease has apparently ended, viable bacteria remain sequestered in these locations. Release of these organisms at a later time can produce reactivation tuberculosis (or secondary TB). This is mainly observed in people with alcoholism, the elderly, or in otherwise immunocompromised individuals ( Figure 22.13 ). Because TB is a chronic disease, chemotherapeutic treatments often continue for months or years. Multidrug resistant (MDR-TB) and extensively drug-resistant (XDR-TB) strains of M. tuberculosis are a growing clinical concern. These strains can arise due to misuse or mismanagement of antibiotic therapies. Therefore, it is imperative that proper multidrug protocols are used to treat these infections. Common antibiotics included in these mixtures are isoniazid, rifampin, ethambutol, and pyrazinamide. A TB vaccine is available that is based on the so-called bacillus Calmette-Guérin (BCG) strain of M. bovis commonly found in cattle. In the United States, the BCG vaccine is only given to health-care workers and members of the military who are at risk of exposure to active cases of TB. It is used more broadly worldwide. Many individuals born in other countries have been vaccinated with BCG strain. BCG is used in many countries with a high prevalence of TB, to prevent childhood tuberculous meningitis and miliary disease. The Mantoux tuberculin skin test ( Figure 22.14 ) is regularly used in the United States to screen for potential TB exposure (see Hypersensitivities ). However, prior vaccinations with the BCG vaccine can cause false-positive results. Chest radiographs to detect Ghon complex formation are required, therefore, to confirm exposure. Link to Learning This short animation describes the mechanisms of infection associated with Mycobacterium tuberculosis. Check Your Understanding What characteristic of Mycobacterium tuberculosis allows it to evade the immune response? What happens to cause miliary tuberculosis? Explain the limitations of the Mantoux tuberculin skin test. Pertussis (Whooping Cough) The causative agent of pertussis , commonly called whooping cough , is Bordetella pertussis , a gram-negative coccobacillus. The disease is characterized by mucus accumulation in the lungs that leads to a long period of severe coughing. Sometimes, following a bout of coughing, a sound resembling a “whoop” is produced as air is inhaled through the inflamed and restricted airway—hence the name whooping cough. Although adults can be infected, the symptoms of this disease are most pronounced in infants and children. Pertussis is highly communicable through droplet transmission, so the uncontrollable coughing produced is an efficient means of transmitting the disease in a susceptible population. Following inhalation, B. pertussis specifically attaches to epithelial cells using an adhesin , filamentous hemagglutinin. The bacteria then grow at the site of infection and cause disease symptoms through the production of exotoxins. One of the main virulence factors of this organism is an A-B exotoxin called the pertussis toxin (PT) . When PT enters the host cells, it increases the cyclic adenosine monophosphate (cAMP) levels and disrupts cellular signaling. PT is known to enhance inflammatory responses involving histamine and serotonin. In addition to PT, B. pertussis produces a tracheal cytotoxin that damages ciliated epithelial cells and results in accumulation of mucus in the lungs. The mucus can support the colonization and growth of other microbes and, as a consequence, secondary infections are common. Together, the effects of these factors produce the cough that characterizes this infection. A pertussis infection can be divided into three distinct stages. The initial infection, termed the catarrhal stage , is relatively mild and unremarkable. The signs and symptoms may include nasal congestion, a runny nose, sneezing, and a low-grade fever. This, however, is the stage in which B. pertussis is most infectious. In the paroxysmal stage , mucus accumulation leads to uncontrollable coughing spasms that can last for several minutes and frequently induce vomiting. The paroxysmal stage can last for several weeks. A long convalescence stage follows the paroxysmal stage, during which time patients experience a chronic cough that can last for up to several months. In fact, the disease is sometimes called the 100-day cough. In infants, coughing can be forceful enough to cause fractures to the ribs, and prolonged infections can lead to death. The CDC reported 20 pertussis-related deaths in 2012, 12 but that number had declined to five by 2015. 13 12 Centers for Disease Control and Prevention. “2012 Final Pertussis Surveillance Report.” 2015. http://www.cdc.gov/pertussis/downloads/pertuss-surv-report-2012.pdf. Accessed July 6, 2016. 13 Centers for Disease Control and Prevention. “2015 Provisional Pertussis Surveillance Report.” 2016. http://www.cdc.gov/pertussis/downloads/pertuss-surv-report-2015-provisional.pdf. Accessed July 6, 2016. During the first 2 weeks of infection, laboratory diagnosis is best performed by culturing the organism directly from a nasopharyngeal (NP) specimen collected from the posterior nasopharynx. The NP specimen is streaked onto Bordet-Gengou medium . The specimens must be transported to the laboratory as quickly as possible, even if transport media are used. Transport times of longer than 24 hours reduce the viability of B. pertussis significantly. Within the first month of infection, B. pertussis can be diagnosed using PCR techniques. During the later stages of infection, pertussis-specific antibodies can be immunologically detected using an enzyme-linked immunosorbent assay (ELISA). Pertussis is generally a self-limiting disease. Antibiotic therapy with erythromycin or tetracycline is only effective at the very earliest stages of disease. Antibiotics given later in the infection, and prophylactically to uninfected individuals, reduce the rate of transmission. Active vaccination is a better approach to control this disease. The DPT vaccine was once in common use in the United States. In that vaccine, the P component consisted of killed whole-cell B. pertussis preparations. Because of some adverse effects, that preparation has now been superseded by the DTaP and Tdap vaccine s. In both of these new vaccines, the “aP” component is a pertussis toxoid. Widespread vaccination has greatly reduced the number of reported cases and prevented large epidemics of pertussis. Recently, however, pertussis has begun to reemerge as a childhood disease in some states because of declining vaccination rates and an increasing population of susceptible children. Link to Learning This web page contains an audio clip of the distinctive “whooping” sound associated with pertussis in infants. This interactive map shows outbreaks of vaccine preventable diseases, including pertussis, around the world. Check Your Understanding What accounts for the mucus production in a pertussis infection? What are the signs and symptoms associated with the three stages of pertussis? Why is pertussis becoming more common in the United States? Legionnaires Disease An atypical pneumonia called Legionnaires disease (also known as legionellosis) is caused by an aerobic gram-negative bacillus, Legionella pneumophila . This bacterium infects free-living amoebae that inhabit moist environments, and infections typically occur from human-made reservoirs such as air-conditioning cooling towers, humidifiers, misting systems, and fountains. Aerosols from these reservoirs can lead to infections of susceptible individuals, especially those suffering from chronic heart or lung disease or other conditions that weaken the immune system. When L. pneumophila bacteria enter the alveoli, they are phagocytized by resident macrophages. However, L. pneumophila uses a secretion system to insert proteins in the endosomal membrane of the macrophage; these proteins prevent lysosomal fusion, allowing L. pneumophila to continue to proliferate within the phagosome. The resulting respiratory disease can range from mild to severe pneumonia, depending on the status of the host’s immune defenses. Although this disease primarily affects the lungs, it can also cause fever, nausea, vomiting, confusion, and other neurological effects. Diagnosis of Legionnaires disease is somewhat complicated. L. pneumophila is a fastidious bacterium and is difficult to culture. In addition, since the bacterial cells are not efficiently stained with the Gram stain, other staining techniques, such as the Warthin-Starry silver-precipitate procedure , must be used to visualize this pathogen. A rapid diagnostic test has been developed that detects the presence of Legionella antigen in a patient’s urine; results take less than 1 hour, and the test has high selectivity and specificity (greater than 90%). Unfortunately, the test only works for one serotype of L. pneumophila (type 1, the serotype responsible for most infections). Consequently, isolation and identification of L. pneumophila from sputum remains the defining test for diagnosis. Once diagnosed, Legionnaire disease can be effectively treated with fluoroquinolone and macrolide antibiotics. However, the disease is sometimes fatal; about 10% of patients die of complications. 14 There is currently no vaccine available. 14 Centers for Disease Control and Prevention. “ Legionella (Legionnaires’ Disease and Pontiac Fever: Diagnosis, Treatment, and Complications).” http://www.cdc.gov/legionella/about/diagnosis.html. Accessed Sept 14, 2016. Check Your Understanding Why is Legionnaires disease associated with air-conditioning systems? How does Legionella pneumophila circumvent the immune system? Q Fever The zoonotic disease Q fever is caused by a rickettsia, Coxiella burnetii . The primary reservoirs for this bacterium are domesticated livestock such as cattle, sheep, and goats. The bacterium may be transmitted by ticks or through exposure to the urine, feces, milk, or amniotic fluid of an infected animal. In humans, the primary route of infection is through inhalation of contaminated farmyard aerosols. It is, therefore, largely an occupational disease of farmers. Humans are acutely sensitive to C. burnetii —the infective dose is estimated to be just a few cells. 15 In addition, the organism is hardy and can survive in a dry environment for an extended time. Symptoms associated with acute Q fever include high fever, headache, coughing, pneumonia, and general malaise. In a small number of patients (less than 5% 16 ), the condition may become chronic, often leading to endocarditis, which may be fatal. 15 WD Tigertt et al. “Airborne Q Fever.” Bacteriological Reviews 25 no. 3 (1961):285–293. 16 Centers for Disease Control and Prevention. “Q fever. Symptoms, Diagnosis, and Treatment.” 2013. http://www.cdc.gov/qfever/symptoms/index.html. Accessed July 6, 2016. Diagnosing rickettsial infection by cultivation in the laboratory is both difficult and hazardous because of the easy aerosolization of the bacteria, so PCR and ELISA are commonly used. Doxycycline is the first-line drug to treat acute Q fever. In chronic Q fever, doxycycline is often paired with hydroxychloroquine . Disease Profile Bacterial Diseases of the Respiratory Tract Numerous pathogens can cause infections of the respiratory tract. Many of these infections produce similar signs and symptoms, but appropriate treatment depends on accurate diagnosis through laboratory testing. The tables in Figure 22.15 and Figure 22.16 summarize the most important bacterial respiratory infections, with the latter focusing specifically on forms of bacterial pneumonia. 22.3 Viral Infections of the Respiratory Tract Learning Objectives Identify the most common viruses that can cause infections of the upper and lower respiratory tract Compare the major characteristics of specific viral diseases of the respiratory tract Viruses are the most frequent cause of respiratory tract infections. Unlike the bacterial pathogens, we have few effective therapies to combat viral respiratory infections. Fortunately, many of these diseases are mild and self-limiting. A few respiratory infections manifest their primary symptoms at other locations in the body. The Common Cold The common cold is a generic term for a variety of mild viral infections of the nasal cavity. More than 200 different viruses are known to cause the common cold. The most common groups of cold viruses include rhinovirus es, coronavirus es, and adenovirus es. These infections are widely disseminated in the human population and are transmitted through direct contact and droplet transmission. Coughing and sneezing efficiently produce infectious aerosols, and rhinoviruses are known to persist on environmental surfaces for up to a week. 17 17 AG L’Huillier et al. “Survival of Rhinoviruses on Human Fingers.” Clinical Microbiology and Infection 21, no. 4 (2015):381–385. Viral contact with the nasal mucosa or eyes can lead to infection. Rhinoviruses tend to replicate best between 33 °C (91.4 °F) and 35 °C (95 °F), somewhat below normal body temperature (37 °C [98.6 °F]). As a consequence, they tend to infect the cooler tissues of the nasal cavities. Colds are marked by an irritation of the mucosa that leads to an inflammatory response. This produces common signs and symptoms such as nasal excess nasal secretions (runny nose), congestion, sore throat, coughing, and sneezing. The absence of high fever is typically used to differentiate common colds from other viral infections, like influenza. Some colds may progress to cause otitis media, pharyngitis, or laryngitis, and patients may also experience headaches and body aches. The disease, however, is self-limiting and typically resolves within 1–2 weeks. There are no effective antiviral treatments for the common cold and antibacterial drugs should not be prescribed unless secondary bacterial infections have been established. Many of the viruses that cause colds are related, so immunity develops throughout life. Given the number of viruses that cause colds, however, individuals are never likely to develop immunity to all causes of the common cold. Check Your Understanding How are colds transmitted? What is responsible for the symptoms of a cold? Clinical Focus Part 3 Since antibiotic treatment had proven ineffective, John’s doctor suspects that a viral or fungal pathogen may be the culprit behind John’s case of pneumonia. Another possibility is that John could have an antibiotic-resistant bacterial infection that will require a different antibiotic or combination of antibiotics to clear. The RIDT tests both came back negative for type A and type B influenza. However, the diagnostic laboratory identified the sputum isolate as Legionella pneumophila . The doctor ordered tests of John’s urine and, on the second day after his admission, results of an enzyme immunoassay (EIA) were positive for the Legionella antigen. John’s doctor added levofloxacin to his antibiotic therapy and continued to monitor him. The doctor also began to ask John where he had been over the past 10 to 14 days. Do negative RIDT results absolutely rule out influenza virus as the etiologic agent? Why or why not? What is John’s prognosis? Jump to the next Clinical Focus box. Go back to the previous Clinical Focus box . Influenza Commonly known as the flu, influenza is a common viral disease caused by an orthomyxovirus that primarily affects the upper respiratory tract but can also extend into the lower respiratory tract. Influenza is pervasive worldwide and causes 3,000–50,000 deaths each year in the United States. The annual mortality rate can vary greatly depending on the virulence of the strain(s) responsible for seasonal epidemics. 18 18 Centers for Disease Control and Prevention. “Estimating Seasonal Influenza-Associated Deaths in the United States: CDC Study Confirms Variability of Flu.” 2016. http://www.cdc.gov/flu/about/disease/us_flu-related_deaths.htm. Accessed July 6, 2016. Influenza infections are most typically characterized by fever, chills, and body aches. This is followed by symptoms similar to the common cold that may last a week or more. Table 22.2 compares the signs and symptoms of influenza and the common cold. Comparing the Common Cold and Influenza Sign/Symptom Common Cold Influenza Fever Low (37.2 °C [99 °F]) High (39 °C [102.2 °F]) Headache Common Common Aches and pains Mild Severe Fatigue Slight Severe Nasal congestion Common Rare Sneezing Common Rare Table 22.2 In general, influenza is self-limiting. However, serious cases can lead to pneumonia and other complications that can be fatal. Such cases are more common in the very young and the elderly; however, certain strains of influenza virus (like the 1918–1919 variant discussed later in this chapter) are more lethal to young adults than to the very young or old. Strains that affect young adults are believed to involve a cytokine storm —a positive feedback loop that forms between cytokine production and leukocytes. This cytokine storm produces an acute inflammatory response that leads to rapid fluid accumulation in the lungs, culminating in pulmonary failure. In such cases, the ability to mount a vigorous immune response is actually detrimental to the patient. The very young and very old are less susceptible to this effect because their immune systems are less robust. A complication of influenza that occurs primarily in children and teenagers is Reye syndrome . This sequela causes swelling in the liver and brain, and may progress to neurological damage, coma, or death. Reye syndrome may follow other viral infections, like chickenpox, and has been associated with the use of aspirin. For this reason, the CDC and other agencies recommend that aspirin and products containing aspirin never be used to treat viral illnesses in children younger than age 19 years. 19 19 ED Belay et al. “Reye’s Syndrome in the United States From 1981 Through 1997.” New England Journal of Medicine 340 no. 18 (1999):1377–1382. The influenza virus is primarily transmitted by direct contact and inhalation of aerosols. The RNA genome of this virus exists as seven or eight segments, each coated with ribonucleoprotein and encoding one or two specific viral proteins. The influenza virus is surrounded by a lipid membrane envelope, and two of the main antigens of the influenza virus are the spike proteins hemagglutinin (H) and neuraminidase (N), as shown in Figure 22.17 . These spike proteins play important roles in the viral infectious cycle. Following inhalation, the influenza virus uses the hemagglutinin protein to bind to sialic acid receptor s on host respiratory epithelial cells. This facilitates endocytosis of the viral particle. Once inside the host cell, the negative strand viral RNA is replicated by the viral RNA polymerase to form mRNA, which is translated by the host to produce viral proteins. Additional viral RNA molecules are transcribed to produce viral genomic RNA, which assemble with viral proteins to form mature virions. Release of the virions from the host cell is facilitated by viral neuraminidase , which cleaves sialic-acid receptors to allow progeny viruses to make a clean exit when budding from an infected cell. There are three genetically related influenza viruses, called A, B, and C. The influenza A viruses have different subtypes based on the structure of their hemagglutinin and neuraminidase proteins. There are currently 18 known subtypes of hemagglutinin and 11 known subtypes of neuraminidase. Influenza viruses are serologically characterized by the type of H and N proteins that they possess. Of the nearly 200 different combinations of H and N, only a few, such as the H1N1 strain, are associated with human disease. The influenza viruses A, B, and C make up three of the five major groups of orthomyxoviruses. The differences between the three types of influenza are summarized in Table 22.3 . The most virulent group is the influenza A virus es, which cause seasonal pandemics of influenza each year. Influenza A virus can infect a variety of animals, including pigs, horses, pigs, and even whales and dolphins. Influenza B virus is less virulent and is sometimes associated with epidemic outbreaks. Influenza C virus generally produces the mildest disease symptoms and is rarely connected with epidemics. Neither influenza B virus nor influenza C virus has significant animal reservoirs. The Three Major Groups of Influenza Viruses   Influenza A virus Influenza B virus Influenza C virus Severity Severe Moderate Mild Animal reservoir Yes No No Genome segments 8 8 7 Population spread Epidemic and pandemic Epidemic Sporadic Antigenic variation Shift/drift Drift Drift Table 22.3 Influenza virus infections elicit a strong immune response, particularly to the hemagglutinin protein, which would protect the individual if they encountered the same virus. Unfortunately, the antigenic properties of the virus change relatively rapidly, so new strains are evolving that immune systems previously challenged by influenza virus cannot recognize. When an influenza virus gains a new hemagglutinin or neuraminidase type, it is able to evade the host’s immune response and be successfully transmitted, often leading to an epidemic. There are two mechanisms by which these evolutionary changes may occur. The mechanisms of antigen drift and antigenic shift for influenza virus have been described in Virulence Factors of Bacterial and Viral Pathogens . Of these two genetic processes, it is viruses produced by antigenic shift that have the potential to be extremely virulent because individuals previously infected by other strains are unlikely to produce any protective immune response against these novel variants. The most lethal influenza pandemic in recorded history occurred from 1918 through 1919. Near the end of World War I, an antigenic shift involving the recombination of avian and human viruses is thought to have produced a new H1N1 virus. This strain rapidly spread worldwide and is commonly claimed to have killed as many as 40 million to 50 million people—more than double the number killed in the war. Although referred to as the Spanish flu , this disease is thought to have originated in the United States. Regardless of its source, the conditions of World War I greatly contributed to the spread of this disease. Crowding, poor sanitation, and rapid mobilization of large numbers of personnel and animals facilitated the dissemination of the new virus once it appeared. Several of the most important influenza pandemics of modern times have been associated with antigenic shifts. A few of these are summarized in Table 22.4 . Historical Influenza Outbreaks 20 21 22 20 CE Mills et al. “Transmissibility of 1918 Pandemic Influenza.” Nature 432, no. 7019 (2004):904–906. 21 E. Tognotti. “Influenza Pandemics: A Historical Retrospect.” Journal of Infection in Developing Countries 3, no. 5 (2009):331–334. 22 FS Dawood et al. “Estimated Global Mortality Associated with the First 12 Months of 2009 Pandemic Influenza A H1N1 Virus Circulation: A Modelling Study.” The Lancet Infectious Diseases 12, no. 9 (2012):687–695. Years Common Name Serotype Estimated Number of Deaths 1918–1919 Spanish flu H1N1 20,000,000–40,000,000 1957–1958 Asian flu N2N2 1,000,000–2,000,000 1968–1969 Hong Kong flu H3N2 1,000,000–3,000,000 2009–2010 Swine flu H1N1/09 152,000–575,000 Table 22.4 Laboratory diagnosis of influenza is typically performed using a variety of RIDTs. These tests are inoculated by point-of-care personnel and give results within 15–20 minutes. Unfortunately, these tests have variable sensitivity and commonly yield false-negative results. Other tests include hemagglutination of erythrocytes (due to hemagglutinin action) or complement fixation. Patient serum antibodies against influenza viruses can also be detected in blood samples. Because influenza is self-limiting disease, diagnosis through these more time-consuming and expensive methods is not typically used. Three drugs that inhibit influenza neuraminidase activity are available: inhaled zanamivir , oral oseltamivir , and intravenous peramivir . If taken at the onset of symptoms, these drugs can shorten the course of the disease. These drugs are thought to impair the ability of the virus to efficiently exit infected host cells. A more effective means of controlling influenza outbreaks, though, is vaccination. Every year, new influenza vaccine s are developed to be effective against the strains expected to be predominant. This is determined in February by a review of the dominant strains around the world from a network of reporting sites; their reports are used to generate a recommendation for the vaccine combination for the following winter in the northern hemisphere. In September, a similar recommendation is made for the winter in the southern hemisphere. 23 These recommendations are used by vaccine manufacturers to formulate each year’s vaccine. In most cases, three or four viruses are selected—the two most prevalent influenza A strains and one or two influenza B strains. The chosen strains are typically cultivated in eggs and used to produce either an inactivated or a live attenuated vaccine (e.g., FluMist). For individuals 18 years or older with an allergy to egg products, a recombinant egg-free trivalent vaccine is available. Most of the influenza vaccines over the past decade have had an effectiveness of about 50%. 24 23 World Health Organization. “WHO Report on Global Surveillance of Epidemic-Prone Infectious Diseases.” 2000. http://www.who.int/csr/resources/publications/surveillance/Influenza.pdf. Accessed July 6, 2016. 24 Centers of Disease Control and Prevention. “Vaccine Effectiveness - How Well Does the Flu Vaccine Work?” 2016. http://www.cdc.gov/flu/about/qa/vaccineeffect.htm. Accessed July 6, 2016. Case in Point Flu Pandemic During the spring of 2013, a new strain of H7N9 influenza was reported in China. A total of 132 people were infected. Of those infected, 44 (33%) died. A genetic analysis of the virus suggested that this strain arose from the reassortment of three different influenza viruses: a domestic duck H7N3 virus, a wild bird H7N9 virus, and a domestic poultry H9N2 virus. The virus was detected in the Chinese domestic bird flocks and contact with this reservoir is thought to have been the primary source of infection. This strain of influenza was not able to spread from person to person. Therefore, the disease did not become a global problem. This case does, though, illustrate the potential threat that influenza still represents. If a strain like the H7N9 virus were to undergo another antigenic shift, it could become more communicable in the human population. With a mortality rate of 33%, such a pandemic would be disastrous. For this reason, organizations like the World Health Organization and the Centers for Disease Control and Prevention keep all known influenza outbreaks under constant surveillance. Check Your Understanding Compare the severity of the three types of influenza viruses. Why must new influenza vaccines be developed each year? Viral Pneumonia Viruses cause fewer cases of pneumonia than bacteria; however, several viruses can lead to pneumonia in children and the elderly. The most common sources of viral pneumonia are adenovirus es, influenza virus es, parainfluenza virus es, and respiratory syncytial virus es. The signs and symptoms produced by these viruses can range from mild cold-like symptoms to severe cases of pneumonia, depending on the virulence of the virus strain and the strength of the host defenses of the infected individual. Occasionally, infections can result in otitis media. Respiratory syncytial virus (RSV) infections are fairly common in infants; most people have been infected by the age of 2 years. During infection, a viral surface protein causes host cells to fuse and form multinucleated giant cells called syncytia . There are no specific antiviral therapies or vaccines available for viral pneumonia. In adults, these infections are self-limiting, resemble the common cold, and tend to resolve uneventfully within 1 or 2 weeks. Infections in infants, however, can be life-threatening. RSV is highly contagious and can be spread through respiratory droplets from coughing and sneezing. RSV can also survive for a long time on environmental surfaces and, thus, be transmitted indirectly via fomites. Check Your Understanding Who is most likely to contract viral pneumonia? What is the recommended treatment for viral pneumonia? SARS and MERS Severe acute respiratory syndrome ( SARS ) and Middle East respiratory syndrome ( MERS ) are two acute respiratory infections caused by coronavirus es. In both cases, these are thought to be zoonotic infections. Bats and civet cats are thought to have been the reservoirs for SARS; camels seem to be the reservoir for MERS. SARS originated in southern China in the winter of 2002 and rapidly spread to 37 countries. Within about 1 year, more than 8,000 people experienced influenza-like symptoms and nearly 800 people died. The rapid spread and severity of these infections caused grave concern at the time. However, the outbreak was controlled in 2003 and no further cases of SARS have been recorded since 2004. 25 Signs and symptoms of SARS include high fever, headache, body aches, and cough, and most patients will develop pneumonia. 25 Y. Huang. “The SARS Epidemic and Its Aftermath in China: A Political Perspective.” In Learning from SARS: Preparing for the Next Disease Outbreak . Edited by S. Knobler et al. Washington, DC: National Academies Press; 2004. Available at: http://www.ncbi.nlm.nih.gov/books/NBK92479/ MERS was first reported in Saudi Arabia in 2013. Although some infected individuals will be asymptomatic or have mild cold-like symptoms, most will develop a high fever, aches, cough and a severe respiratory infection that can progress to pneumonia. As of 2015, over 1,300 people in 27 countries have been infected. About 500 people have died. There are no specific treatments for either MERS or SARS. In addition, no vaccines are currently available. Several recombinant vaccines, however, are being developed. Check Your Understanding What is the cause of SARS? What are the signs and symptoms of MERS? Viral Respiratory Diseases Causing Skin Rashes Measles, rubella (German measles), and chickenpox are three important viral diseases often associated with skin rashes. However, their symptoms are systemic, and because their portal of entry is the respiratory tract, they can be considered respiratory infections. Measles (Rubeola) The measles virus (MeV) causes the highly contagious disease measles , also known as rubeola, which is a major cause of childhood mortality worldwide. Although vaccination efforts have greatly reduced the incidence of measles in much of the world, epidemics are still common in unvaccinated populations in certain countries. 26 26 Centers for Disease Control and Prevention. “Global Health - Measles, Rubella, and CRS, Eliminating Measles, Rubella & Congenital Rubella Syndrome (CRS) Worldwide.” 2015. http://www.cdc.gov/globalhealth/measles/. Accessed July 7, 2016. The measles virus is a single-stranded, negative-strand RNA virus and, like the influenza virus, it possesses an envelope with spikes of embedded hemagglutinin. The infection is spread by direct contact with infectious secretions or inhalation of airborne droplets spread by breathing, coughing, or sneezing. Measles is initially characterized by a high fever, conjunctivitis, and a sore throat. The virus then moves systemically through the bloodstream and causes a characteristic rash. The measles rash initially forms on the face and later spreads to the extremities. The red, raised macular rash will eventually become confluent and can last for several days. At the same time, extremely high fevers (higher than 40.6 °C [105 °F]) can occur. Another diagnostic sign of measles infections is Koplik’s spots , white spots that form on the inner lining of inflamed cheek tissues ( Figure 22.18 ). Although measles is usually self-limiting, it can lead to pneumonia, encephalitis , and death. In addition, the inhibition of immune system cells by the measles virus predisposes patients to secondary infections. In severe infections with highly virulent strains, measles fatality rates can be as high as 10% to 15%. There were more than 145,000 measles deaths (mostly young children) worldwide in 2013. 27 27 World Health Organization. “Measles Factsheet.” 2016. http://www.who.int/mediacentre/factsheets/fs286/en/. Accessed July 7, 2016. The preliminary diagnosis of measles is typically based on the appearance of the rash and Koplik’s spots. Hemagglutination inhibition tests and serological tests may be used to confirm measles infections in low-prevalence settings. There are no effective treatments for measles. Vaccination is widespread in developed countries as part of the measles, mumps, and rubella ( MMR ) vaccine. As a result, there are typically fewer than 200 cases of measles in the United States annually. 28 When it is seen, it is often associated with children who have not been vaccinated. 28 Centers for Disease Control and Prevention. “Measles Cases and Outbreaks.” 2016. http://www.cdc.gov/measles/cases-outbreaks.html. Accessed July 7, 2016. Micro Connections Preventable Measles Outbreaks In December 2014, a measles epidemic began at Disneyland in southern California. Within just 4 months, this outbreak affected 134 people in 24 states. 29 Characterization of the virus suggests that an unidentified infected individual brought the disease to the United States from the Philippines, where a similar virus had sickened more than 58,000 people and killed 110. 30 Measles is highly communicable, and its spread at Disneyland may have been facilitated by the low vaccination rate in some communities in California. 31 29 Ibid. 30 World Health Organization. “Measles-Rubella Bulletin.” Manila, Philippines; Expanded Programme on Immunization Regional Office for the Western Pacific World Health Organization; 9 no. 1 (2015). http://www.wpro.who.int/immunization/documents/mrbulletinvol9issue1.pdf 31 M. Bloch et al. “Vaccination Rates for Every Kindergartener in California.” The New York Times February 6, 2015. http://www.nytimes.com/interactive/2015/02/06/us/california-measles-vaccines-map.html?_r=1. Accessed July 7, 2016. Several factors could conceivably lead to a strong comeback of measles in the U.S. Measles is still an epidemic disease in many locations worldwide. Air travel enables infected individuals to rapidly translocate these infections globally. Compounding this problem, low vaccination rates in some local areas in the United States (such as in Amish communities) provide populations of susceptible hosts for the virus to establish itself. Finally, measles has been a low-prevalence infection in the U.S. for some time. As a consequence, physicians are not as likely to recognize the initial symptoms and make accurate diagnoses. Until vaccination rates become high enough to ensure herd immunity, measles is likely to be an ongoing problem in the United States. Rubella (German Measles) Rubella, or the German measles , is a relatively mild viral disease that produces a rash somewhat like that caused by the measles, even though the two diseases are unrelated. The rubella virus is an enveloped RNA virus that can be found in the respiratory tract. It is transmitted from person to person in aerosols produced by coughing or sneezing. Nearly half of all infected people remain asymptomatic. However, the virus is shed and spread by asymptomatic carriers. Like rubeola, rubella begins with a facial rash that spreads to the extremities ( Figure 22.19 ). However, the rash is less intense, shorter lived (2–3 days), not associated with Koplik’s spots, and the resulting fever is lower (101 °F [38.3 °C]). Congenital rubella syndrome is the most severe clinical complication of the German measles. This occurs if a woman is infected with rubella during pregnancy . The rubella virus is teratogenic , meaning it can cause developmental defects if it crosses the placenta during pregnancy. There is a very high incidence of stillbirth, spontaneous abortion, or congenital birth defects if the mother is infected before 11 weeks of pregnancy and 35% if she is infected between weeks 13–16; after this time the incidence is low. 32 For this reason, prenatal screening for rubella is commonly practiced in the United States. Postnatal infections are usually self-limiting and rarely cause severe complications. 32 E. Miller et al. “Consequences of Confirmed Maternal Rubella at Successive Stages of Pregnancy.” The Lancet 320, no. 8302 (1982):781–784. Like measles, the preliminary diagnosis of rubella is based on the patient’s history, vaccination records, and the appearance of the rash. The diagnosis can be confirmed by hemagglutinin inhibition assays and a variety of other immunological techniques. There are no antiviral therapies for rubella, but an effective vaccine ( MMR ) is widely available. Vaccination efforts have essentially eliminated rubella in the United States; fewer than a dozen cases are reported in a typical year. Chickenpox and Shingles Chickenpox, also known as varicella , was once a common viral childhood disease. The causative agent of chickenpox , the varicella-zoster virus , is a member of the herpesvirus family. In children, the disease is mild and self-limiting, and is easily transmitted by direct contact or inhalation of material from the skin lesions. In adults, however, chickenpox infections can be much more severe and can lead to pneumonia and birth defects in the case of infected pregnant women. Reye syndrome , mentioned earlier in this chapter, is also a serious complication associated with chickenpox, generally in children. Once infected, most individuals acquire a lifetime immunity to future chickenpox outbreaks. For this reason, parents once held “chickenpox parties” for their children. At these events, uninfected children were intentionally exposed to an infected individual so they would contract the disease earlier in life, when the incidence of complications is very low, rather than risk a more severe infection later. After the initial viral exposure, chickenpox has an incubation period of about 2 weeks. The initial infection of the respiratory tract leads to viremia and eventually produces fever and chills. A pustular rash then develops on the face, progresses to the trunk, and then the extremities, although most form on the trunk ( Figure 22.20 ). Eventually, the lesions burst and form a crusty scab. Individuals with chickenpox are infectious from about 2 days before the outbreak of the rash until all the lesions have scabbed over. Like other herpesviruses, the varicella-zoster virus can become dormant in nerve cells. While the pustular vesicles are developing, the virus moves along sensory nerves to the dorsal ganglia in the spinal cord. Once there, the varicella-zoster virus can remain latent for decades. These dormant viruses may be reactivated later in life by a variety of stimuli, including stress, aging, and immunosuppression. Once reactivated, the virus moves along sensory nerves to the skin of the face or trunk. This results in the production of the painful lesions in a condition known as shingles ( Figure 22.21 ). These symptoms generally last for 2–6 weeks, and may recur more than once. Postherpetic neuralgia, pain signals sent from damaged nerves long after the other symptoms have subsided, is also possible. In addition, the virus can spread to other organs in immunocompromised individuals. A person with shingles lesions can transmit the virus to a nonimmune contact, and the newly infected individual would develop chickenpox as the primary infection. Shingles cannot be transmitted from one person to another. The primary diagnosis of chickenpox in children is mainly based on the presentation of a pustular rash of the trunk. Serological and PCR-based tests are available to confirm the initial diagnosis. Treatment for chickenpox infections in children is usually not required. In patients with shingles, acyclovir treatment can often reduce the severity and length of symptoms, and diminish the risk of postherpetic neuralgia. An effective vaccine is now available for chickenpox. A vaccine is also available for adults older than 60 years who were infected with chickenpox in their youth. This vaccine reduces the likelihood of a shingles outbreak by boosting the immune defenses that are keeping the latent infection in check and preventing reactivation. Check Your Understanding Why does measles often lead to secondary infections? What signs or symptoms would distinguish rubella and measles? Why can chickenpox lead to shingles later in life? Eye on Ethics Smallpox Stockpiles Smallpox has probably killed more humans than any other infectious disease, with the possible exception of tuberculosis. This disease, caused by the variola major virus, is transmitted by inhalation of viral particles shed from lesions in the throat. The smallpox virus spreads systemically in the bloodstream and produces a pustular skin rash. Historical epidemics of smallpox had fatality rates of 50% or greater in susceptible populations. Concerted worldwide vaccination efforts eradicated smallpox from the general population in 1977. This was the first microbial disease in history to be eradicated, a feat made possible by the fact that the only reservoir for the smallpox virus is infected humans. Although the virus is no longer present in the wild, laboratory samples of the virus still exist in the United States and Russia. 33 The question is, why do these samples still exist? Some claim that these stocks should be maintained for research purposes. Should the smallpox virus ever reappear, they say, we would need access to such stocks for development of vaccines and treatments. Concerns about a re-emergence of the virus are not totally unfounded. Although there are no living reservoirs of the virus, there is always the possibility that smallpox could re-emerge from mummified human bodies or human remains preserved in permafrost. It is also possible that there are as-yet undiscovered samples of the virus in other locations around the world. An example of such "lost" samples was discovered in a drawer in a Food and Drug Administration lab in Maryland. 34 If an outbreak from such a source were to occur, it could lead to uncontrolled epidemics, since the population is largely unvaccinated now. 33 Centers for Disease Control and Prevention. “CDC Media Statement on Newly Discovered Smallpox Specimens.” July 8, 2014. http://www.cdc.gov/media/releases/2014/s0708-nih.html. Accessed on July 7, 2016. 34 Ibid. Critics of this argument, including many research scientists and the World Health Organization, claim that there is no longer any rational argument for keeping the samples. They view the “re-emergence scenarios” as a thinly veiled pretense for harboring biological weapons. These scenarios, they say, are less probable than an intentional reintroduction of the virus from militarized stocks by humans. Furthermore, they point out that if we needed to research smallpox in the future, we could rebuild the virus from its DNA sequence. What do you think? Are there legitimate arguments for maintaining stockpiles of smallpox, or should all forms of this deadly disease be eradicated? Disease Profile Viral Infections of the Respiratory Tract Many viruses are capable of entering and causing disease in the respiratory system, and a number are able to spread beyond the respiratory system to cause systemic infections. Most of these infections are highly contagious and, with a few exceptions, antimicrobial drugs are not effective for treatment. Although some of these infections are self-limiting, others can have serious or fatal complications. Effective vaccines have been developed for several of these diseases, as summarized in Figure 22.22 . 22.4 Respiratory Mycoses Learning Objectives Identify the most common fungi that can cause infections of the respiratory tract Compare the major characteristics of specific fungal diseases of the respiratory tract Fungal pathogens are ubiquitous in the environment. Serological studies have demonstrated that most people have been exposed to fungal respiratory pathogens during their lives. Yet symptomatic infections by these microbes are rare in healthy individuals. This demonstrates the efficacy of the defenses of our respiratory system. In this section, we will examine some of the fungi that can cause respiratory infections. Histoplasmosis Histoplasmosis is a fungal disease of the respiratory system and most commonly occurs in the Mississippi Valley of the United States and in parts of Central and South America, Africa, Asia, and Australia. The causative agent, Histoplasma capsulatum , is a dimorphic fungus. This microbe grows as a filamentous mold in the environment but occurs as a budding yeast during human infections. The primary reservoir for this pathogen is soil, particularly in locations rich in bat or bird feces. Histoplasmosis is acquired by inhaling microconidial spores in the air; this disease is not transmitted from human to human. The incidence of histoplasmosis exposure is high in endemic areas, with 60%–90% of the population having anti- Histoplasma antibodies, depending on location; 35 however, relatively few individuals exposed to the fungus actually experience symptoms. Those most likely to be affected are the very young, the elderly, and immunocompromised people. 35 NE Manos et al. “Geographic Variation in the Prevalence of Histoplasmin Sensitivity.” Dis Chest 29, no. 6 (1956):649–668. In many ways, the course of this disease is similar to that of tuberculosis. Following inhalation, the spores enter the lungs and are phagocytized by alveolar macrophages. The fungal cells then survive and multiply within these phagocytes (see Figure 5.26 ). Focal infections cause the formation of granulomatous lesions, which can lead to calcifications that resemble the Ghon complexes of tuberculosis, even in asymptomatic cases. Also like tuberculosis, histoplasmosis can become chronic and reactivation can occur, along with dissemination to other areas of the body (e.g., the liver or spleen). Signs and symptoms of pulmonary histoplasmosis include fever, headache, and weakness with some chest discomfort. The initial diagnosis is often based on chest radiographs and cultures grown on fungal selective media like Sabouraud's dextrose agar . Direct fluorescence antibody staining and Giemsa staining can also be used to detect this pathogen. In addition, serological tests including a complement fixation assay and histoplasmin sensitivity can be used to confirm the diagnosis. In most cases, these infections are self-limiting and antifungal therapy is not required. However, in disseminated disease, the antifungal agents amphotericin B and ketoconazole are effective; itraconazole may be effective in immunocompromised patients, in whom the disease can be more serious. Check Your Understanding In what environments is one more likely to be infected with histoplasmosis? Identify at least two similarities between histoplasmosis and tuberculosis. Coccidioidomycosis Infection by the dimorphic fungus Coccidioides immitis causes coccidioidomycosis . Because the microbe is endemic to the San Joaquin Valley of California, the disease is sometimes referred to as Valley fever. A related species that causes similar infections is found in semi-arid and arid regions of the southwestern United States, Mexico, and Central and South America. 36 36 DR Hospenthal. “Coccioidomycosis.” Medscape. 2015. http://emedicine.medscape.com/article/215978-overview. Accessed July 7, 2016. Like histoplasmosis, coccidioidomycosis is acquired by inhaling fungal spores—in this case, arthrospores formed by hyphal fragmentation. Once in the body, the fungus differentiates into spherules that are filled with endospores. Most C. immitis infections are asymptomatic and self-limiting. However, the infection can be very serious for immunocompromised patients. The endospores may be transported in the blood, disseminating the infection and leading to the formation of granulomatous lesions on the face and nose ( Figure 22.23 ). In severe cases, other major organs can become infected, leading to serious complications such as fatal meningitis . Coccidioidomycosis can be diagnosed by culturing clinical samples. C. immitis readily grows on laboratory fungal media, such as Sabouraud's dextrose agar , at 35 °C (95 °F). Culturing the fungus, however, is rather dangerous. C. immitis is one of the most infectious fungal pathogens known and is capable of causing laboratory-acquired infections. Indeed, until 2012, this organism was considered a “select agent” of bioterrorism and classified as a BSL-3 microbe . Serological tests for antibody production are more often used for diagnosis. Although mild cases generally do not require intervention, disseminated infections can be treated with intravenous antifungal drugs like amphotericin B . Clinical Focus Resolution John’s negative RIDT tests do not rule out influenza, since false-negative results are common, but the Legionella infection still must be treated with antibiotic therapy and is the more serious condition. John's prognosis is good, provided the physician can find an antibiotic therapy to which the infection responds. While John was undergoing treatment, three of the employees from the home improvement store also reported to the clinic with very similar symptoms. All three were older than 55 years and had Legionella antigen in their urine; L. pneumophila was also isolated from their sputum. A team from the health department was sent to the home improvement store to identify a probable source for these infections. Their investigation revealed that about 3 weeks earlier, the store's air conditioning system, which was located where the employees ate lunch, had been undergoing maintenance. L. pneumophila was isolated from the cooling coils of the air conditioning system and intracellular L. pneumophila was observed in amoebae in samples of condensed water from the cooling coils as well ( Figure 22.24 ). The amoebae provide protection for the Legionella bacteria and are known to enhance their pathogenicity. 37 37 HY Lau and NJ Ashbolt. “The Role of Biofilms and Protozoa in Legionella Pathogenesis: Implications for Drinking Water.” Journal of Applied Microbiology 107 no. 2 (2009):368–378. In the wake of the infections, the store ordered a comprehensive cleaning of the air conditioning system and implemented a regular maintenance program to prevent the growth of biofilms within the cooling tower. They also reviewed practices at their other facilities. After a month of rest at home, John recovered from his infection enough to return to work, as did the other three employees of the store. However, John experienced lethargy and joint pain for more than a year after his treatment. Go back to the previous Clinical Focus box . Blastomycosis Blastomycosis is a rare disease caused by another dimorphic fungus, Blastomyces dermatitidis . Like Histoplasma and Coccidioides , Blastomyces uses the soil as a reservoir, and fungal spores can be inhaled from disturbed soil. The pulmonary form of blastomycosis generally causes mild flu-like symptoms and is self-limiting. It can, however, become disseminated in immunocompromised people, leading to chronic cutaneous disease with subcutaneous lesions on the face and hands ( Figure 22.25 ). These skin lesions eventually become crusty and discolored and can result in deforming scars. Systemic blastomycosis is rare, but if left untreated, it is always fatal. Preliminary diagnosis of pulmonary blastomycosis can be made by observing the characteristic budding yeast forms in sputum samples. Commercially available urine antigen tests are now also available. Additional confirmatory tests include serological assays such as immunodiffusion tests or EIA. Most cases of blastomycosis respond well to amphotericin B or ketoconazole treatments. Link to Learning Watch this profile of a blastomycosis lung infection. Mucormycosis A variety of fungi in the order Mucorales cause mucormycosis , a rare fungal disease. These include bread molds, like Rhizopus and Mucor ; the most commonly associated species is Rhizopus arrhizus (oryzae) (see Figure 5.28 ). These fungi can colonize many different tissues in immunocompromised patients, but often infect the skin, sinuses, or the lungs. Although most people are regularly exposed to the causative agents of mucormycosis, infections in healthy individuals are rare. Exposure to spores from the environment typically occurs through inhalation, but the spores can also infect the skin through a wound or the gastrointestinal tract if ingested. Respiratory mucormycosis primarily affects immunocompromised individuals, such as patients with cancer or those who have had a transplant. 38 38 Centers for Disease Control and Prevention. “Fungal Diseases. Definition of Mucormycosis.” 2015 http://www.cdc.gov/fungal/diseases/mucormycosis/definition.html. Accessed July 7, 2016. After the spores are inhaled, the fungi grow by extending hyphae into the host’s tissues. Infections can occur in both the upper and lower respiratory tracts. Rhinocerebral mucormycosis is an infection of the sinuses and brain; symptoms include headache, fever, facial swelling, congestion, and tissue necrosis causing black lesions in the oral cavity. Pulmonary mucormycosis is an infection of the lungs; symptoms include fever, cough, chest pain, and shortness of breath. In severe cases, infections may become disseminated and involve the central nervous system, leading to coma and death. 39 39 Centers for Disease Control and Prevention. “Fungal Diseases. Symptoms of Mucormycosis.” 2015 http://www.cdc.gov/fungal/diseases/mucormycosis/symptoms.html. Accessed July 7, 2016. Diagnosing mucormycosis can be challenging. Currently, there are no serological or PCR-based tests available to identify these infections. Tissue biopsy specimens must be examined for the presence of the fungal pathogens. The causative agents, however, are often difficult to distinguish from other filamentous fungi. Infections are typically treated by the intravenous administration of amphotericin B , and superficial infections are removed by surgical debridement. Since the patients are often immunocompromised, viral and bacterial secondary infections commonly develop. Mortality rates vary depending on the site of the infection, the causative fungus, and other factors, but a recent study found an overall mortality rate of 54%. 40 40 MM Roden et al. “Epidemiology and Outcome of Zygomycosis: A Review of 929 Reported Cases.” Clinical Infectious Diseases 41 no. 5 (2005):634–653. Check Your Understanding Compare the modes of transmission for coccidioidomycosis, blastomycosis, and mucormycosis. In general, which are more serious: the pulmonary or disseminated forms of these infections? Aspergillosis Aspergillus is a common filamentous fungus found in soils and organic debris. Nearly everyone has been exposed to this mold, yet very few people become sick. In immunocompromised patients, however, Aspergillus may become established and cause aspergillosis . Inhalation of spores can lead to asthma-like allergic reactions. The symptoms commonly include shortness of breath, wheezing, coughing, runny nose, and headaches. Fungal balls, or aspergilloma, can form when hyphal colonies collect in the lungs ( Figure 22.26 ). The fungal hyphae can invade the host tissues, leading to pulmonary hemorrhage and a bloody cough. In severe cases, the disease may progress to a disseminated form that is often fatal. Death most often results from pneumonia or brain hemorrhages. Laboratory diagnosis typically requires chest radiographs and a microscopic examination of tissue and respiratory fluid samples. Serological tests are available to identify Aspergillus antigens. In addition, a skin test can be performed to determine if the patient has been exposed to the fungus. This test is similar to the Mantoux tuberculin skin test used for tuberculosis. Aspergillosis is treated with intravenous antifungal agents, including itraconazole and voriconazole . Allergic symptoms can be managed with corticosteroids because these drugs suppress the immune system and reduce inflammation. However, in disseminated infections, corticosteroids must be discontinued to allow a protective immune response to occur. Pneumocystis Pneumonia A type of pneumonia called Pneumocystis pneumonia (PCP) is caused by Pneumocystis jirovecii . Once thought to be a protozoan, this organism was formerly named P. carinii but it has been reclassified as a fungus and renamed based on biochemical and genetic analyses. Pneumocystis is a leading cause of pneumonia in patients with acquired immunodeficiency syndrome (AIDS) and can be seen in other compromised patients and premature infants. Respiratory infection leads to fever, cough, and shortness of breath. Diagnosis of these infections can be difficult. The organism is typically identified by microscopic examination of tissue and fluid samples from the lungs ( Figure 22.27 ). A PCR-based test is available to detect P. jirovecii in asymptomatic patients with AIDS. The best treatment for these infections is the combination drug trimethoprim-sulfamethoxazole (TMP/SMZ). These sulfa drugs often have adverse effects, but the benefits outweigh these risks. Left untreated, PCP infections are often fatal. Cryptococcosis Infection by the encapsulated yeast Cryptococcus neoformans causes cryptococcosis . This fungus is ubiquitous in the soil and can be isolated from bird feces. Immunocompromised people are infected by inhaling basidiospores found in aerosols. The thick polysaccharide capsule surrounding these microbes enables them to avoid clearance by the alveolar macrophage. Initial symptoms of infection include fever, fatigue, and a dry cough. In immunocompromised patients, pulmonary infections often disseminate to the brain. The resulting meningitis produces headaches, sensitivity to light, and confusion. Left untreated, such infections are often fatal. Cryptococcus infections are often diagnosed based on microscopic examination of lung tissues or cerebrospinal fluids. India ink preparations ( Figure 22.28 ) can be used to visualize the extensive capsules that surround the yeast cells. Serological tests are also available to confirm the diagnosis. Amphotericin B, in combination with flucytosine , is typically used for the initial treatment of pulmonary infections. Amphotericin B is a broad-spectrum antifungal drug that targets fungal cell membranes. It can also adversely impact host cells and produce side effects. For this reason, clinicians must carefully balance the risks and benefits of treatments in these patients. Because it is difficult to eradicate cryptococcal infections, patients usually need to take fluconazole for up to 6 months after treatment with amphotericin B and flucytosine to clear the fungus. Cryptococcal infections are more common in immunocompromised people, such as those with AIDS. These patients typically require life-long suppressive therapy to control this fungal infection. Check Your Understanding What populations are most at risk for developing Pneumocystis pneumonia or cryptococcosis? Why are these infections fatal if left untreated? Disease Profile Fungal Diseases of the Respiratory Tract Most respiratory mycoses are caused by fungi that inhabit the environment. Such infections are generally transmitted via inhalation of fungal spores and cannot be transmitted between humans. In addition, healthy people are generally not susceptible to infection even when exposed; the fungi are only virulent enough to establish infection in patients with HIV, AIDS, or another condition that compromises the immune defenses. Figure 22.29 summarizes the features of important respiratory mycoses.
microbiology
Summary 3.1 Spontaneous Generation The theory of spontaneous generation states that life arose from nonliving matter. It was a long-held belief dating back to Aristotle and the ancient Greeks. Experimentation by Francesco Redi in the 17th century presented the first significant evidence refuting spontaneous generation by showing that flies must have access to meat for maggots to develop on the meat. Prominent scientists designed experiments and argued both in support of (John Needham) and against (Lazzaro Spallanzani) spontaneous generation. Louis Pasteur is credited with conclusively disproving the theory of spontaneous generation with his famous swan-neck flask experiment. He subsequently proposed that “life only comes from life.” 3.2 Foundations of Modern Cell Theory Although cells were first observed in the 1660s by Robert Hooke, cell theory was not well accepted for another 200 years. The work of scientists such as Schleiden, Schwann, Remak, and Virchow contributed to its acceptance. Endosymbiotic theory states that mitochondria and chloroplasts, organelles found in many types of organisms, have their origins in bacteria. Significant structural and genetic information support this theory. The miasma theory of disease was widely accepted until the 19th century, when it was replaced by the germ theory of disease thanks to the work of Semmelweis, Snow, Pasteur, Lister, and Koch, and others. 3.3 Unique Characteristics of Prokaryotic Cells Prokaryotic cells differ from eukaryotic cells in that their genetic material is contained in a nucleoid rather than a membrane-bound nucleus. In addition, prokaryotic cells generally lack membrane-bound organelles. Prokaryotic cells of the same species typically share a similar cell morphology and cellular arrangement . Most prokaryotic cells have a cell wall that helps the organism maintain cellular morphology and protects it against changes in osmotic pressure. Outside of the nucleoid, prokaryotic cells may contain extrachromosomal DNA in plasmids . Prokaryotic ribosomes that are found in the cytoplasm have a size of 70S. Some prokaryotic cells have inclusions that store nutrients or chemicals for other uses. Some prokaryotic cells are able to form endospores through sporulation to survive in a dormant state when conditions are unfavorable. Endospores can germinate , transforming back into vegetative cells when conditions improve. In prokaryotic cells, the cell envelope includes a plasma membrane and usually a cell wall. Bacterial membranes are composed of phospholipids with integral or peripheral proteins. The fatty acid components of these phospholipids are ester-linked and are often used to identify specific types of bacteria. The proteins serve a variety of functions, including transport, cell-to-cell communication, and sensing environmental conditions. Archaeal membranes are distinct in that they are composed of fatty acids that are ether-linked to phospholipids. Some molecules can move across the bacterial membrane by simple diffusion, but most large molecules must be actively transported through membrane structures using cellular energy. Prokaryotic cell walls may be composed of peptidoglycan (bacteria) or pseudopeptidoglycan (archaea). Gram-positive bacterial cells are characterized by a thick peptidoglycan layer, whereas gram-negative bacterial cells are characterized by a thin peptidoglycan layer surrounded by an outer membrane. Some prokaryotic cells produce glycocalyx coatings, such as capsules and slime layers , that aid in attachment to surfaces and/or evasion of the host immune system. Some prokaryotic cells have fimbriae or pili , filamentous appendages that aid in attachment to surfaces. Pili are also used in the transfer of genetic material between cells. Some prokaryotic cells use one or more flagella to move through water. Peritrichous bacteria, which have numerous flagella, use runs and tumbles to move purposefully in the direction of a chemical attractant. 3.4 Unique Characteristics of Eukaryotic Cells Eukaryotic cells are defined by the presence of a nucleus containing the DNA genome and bound by a nuclear membrane (or nuclear envelope ) composed of two lipid bilayers that regulate transport of materials into and out of the nucleus through nuclear pores. Eukaryotic cell morphologies vary greatly and may be maintained by various structures, including the cytoskeleton, the cell membrane, and/or the cell wall The nucleolus , located in the nucleus of eukaryotic cells, is the site of ribosomal synthesis and the first stages of ribosome assembly. Eukaryotic cells contain 80S ribosomes in the rough endoplasmic reticulum ( membrane bound-ribosomes ) and cytoplasm ( free ribosomes ). They contain 70s ribosomes in mitochondria and chloroplasts. Eukaryotic cells have evolved an endomembrane system, containing membrane-bound organelles involved in transport. These include vesicles, the endoplasmic reticulum, and the Golgi apparatus. The smooth endoplasmic reticulum plays a role in lipid biosynthesis, carbohydrate metabolism, and detoxification of toxic compounds. The rough endoplasmic reticulum contains membrane-bound 80S ribosomes that synthesize proteins destined for the cell membrane The Golgi apparatus processes proteins and lipids, typically through the addition of sugar molecules, producing glycoproteins or glycolipids, components of the plasma membrane that are used in cell-to-cell communication. Lysosomes contain digestive enzymes that break down small particles ingested by endocytosis , large particles or cells ingested by phagocytosis , and damaged intracellular components. The cytoskeleton , composed of microfilaments , intermediate filaments , and microtubules , provides structural support in eukaryotic cells and serves as a network for transport of intracellular materials. Centrosomes are microtubule-organizing centers important in the formation of the mitotic spindle in mitosis. Mitochondria are the site of cellular respiration. They have two membranes: an outer membrane and an inner membrane with cristae. The mitochondrial matrix, within the inner membrane, contains the mitochondrial DNA, 70S ribosomes, and metabolic enzymes. The plasma membrane of eukaryotic cells is structurally similar to that found in prokaryotic cells, and membrane components move according to the fluid mosaic model. However, eukaryotic membranes contain sterols, which alter membrane fluidity, as well as glycoproteins and glycolipids, which help the cell recognize other cells and infectious particles. In addition to active transport and passive transport, eukaryotic cell membranes can take material into the cell via endocytosis , or expel matter from the cell via exocytosis. Cells of fungi, algae, plants, and some protists have a cell wall, whereas cells of animals and some protozoans have a sticky extracellular matrix that provides structural support and mediates cellular signaling. Eukaryotic flagella are structurally distinct from prokaryotic flagella but serve a similar purpose (locomotion). Cilia are structurally similar to eukaryotic flagella, but shorter; they may be used for locomotion, feeding, or movement of extracellular particles.
Chapter Outline 3.1 Spontaneous Generation 3.2 Foundations of Modern Cell Theory 3.3 Unique Characteristics of Prokaryotic Cells 3.4 Unique Characteristics of Eukaryotic Cells Introduction Life takes many forms, from giant redwood trees towering hundreds of feet in the air to the tiniest known microbes, which measure only a few billionths of a meter. Humans have long pondered life’s origins and debated the defining characteristics of life, but our understanding of these concepts has changed radically since the invention of the microscope. In the 17th century, observations of microscopic life led to the development of the cell theory: the idea that the fundamental unit of life is the cell, that all organisms contain at least one cell, and that cells only come from other cells. Despite sharing certain characteristics, cells may vary significantly. The two main types of cells are prokaryotic cells (lacking a nucleus) and eukaryotic cells (containing a well-organized, membrane-bound nucleus). Each type of cell exhibits remarkable variety in structure, function, and metabolic activity ( Figure 3.1 ). This chapter will focus on the historical discoveries that have shaped our current understanding of microbes, including their origins and their role in human disease. We will then explore the distinguishing structures found in prokaryotic and eukaryotic cells.
[ { "answer": { "ans_choice": 2, "ans_text": "C" }, "bloom": null, "hl_context": "<hl> In 1745 , John Needham ( 1713 – 1781 ) published a report of his own experiments , in which he briefly boiled broth infused with plant or animal matter , hoping to kill all preexisting microbes . <hl> 2 He then sealed the flasks . After a few days , Needham observed that the broth had become cloudy and a single drop contained numerous microscopic creatures . <hl> He argued that the new microbes must have arisen spontaneously . <hl> In reality , however , he likely did not boil the broth enough to kill all preexisting microbes . 2 E . Capanna . “ Lazzaro Spallanzani : At the Roots of Modern Biology . ” Journal of Experimental Zoology 285 no . 3 ( 1999 ): 178 – 196 .", "hl_sentences": "In 1745 , John Needham ( 1713 – 1781 ) published a report of his own experiments , in which he briefly boiled broth infused with plant or animal matter , hoping to kill all preexisting microbes . He argued that the new microbes must have arisen spontaneously .", "question": { "cloze_format": "The individual that argued in favor of the theory of spontaneous generation was ___.", "normal_format": "Which of the following individuals argued in favor of the theory of spontaneous generation?", "question_choices": [ "Francesco Redi", "Louis Pasteur", "John Needham", "Lazzaro Spallanzani" ], "question_id": "fs-id1172100666776", "question_text": "Which of the following individuals argued in favor of the theory of spontaneous generation?" }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 3, "ans_text": "D" }, "bloom": null, "hl_context": "<hl> Pasteur ’ s set of experiments irrefutably disproved the theory of spontaneous generation and earned him the prestigious Alhumbert Prize from the Paris Academy of Sciences in 1862 . <hl> In a subsequent lecture in 1864 , Pasteur articulated “ Omne vivum ex vivo ” ( “ Life only comes from life ” ) . <hl> In this lecture , Pasteur recounted his famous swan-neck flask experiment , stating that “ … life is a germ and a germ is life . <hl> Never will the doctrine of spontaneous generation recover from the mortal blow of this simple experiment . ” 4 To Pasteur ’ s credit , it never has . 4 R . Vallery-Radot . The Life of Pasteur , trans . R . L . Devonshire . New York : McClure , Phillips and Co , 1902 , 1:142 .", "hl_sentences": "Pasteur ’ s set of experiments irrefutably disproved the theory of spontaneous generation and earned him the prestigious Alhumbert Prize from the Paris Academy of Sciences in 1862 . In this lecture , Pasteur recounted his famous swan-neck flask experiment , stating that “ … life is a germ and a germ is life .", "question": { "cloze_format": "___ is the individual who is credited for definitively refuting the theory of spontaneous generation using broth in swan-neck flask.", "normal_format": "Which of the following individuals is credited for definitively refuting the theory of spontaneous generation using broth in swan-neck flask?", "question_choices": [ "Aristotle", "Jan Baptista van Helmont", "John Needham", "Louis Pasteur" ], "question_id": "fs-id1172100494753", "question_text": "Which of the following individuals is credited for definitively refuting the theory of spontaneous generation using broth in swan-neck flask?" }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 3, "ans_text": "D" }, "bloom": null, "hl_context": "<hl> However , one of van Helmont ’ s contemporaries , Italian physician Francesco Redi ( 1626 – 1697 ) , performed an experiment in 1668 that was one of the first to refute the idea that maggots ( the larvae of flies ) spontaneously generate on meat left out in the open air . <hl> He predicted that preventing flies from having direct contact with the meat would also prevent the appearance of maggots . Redi left meat in each of six containers ( Figure 3.2 ) . Two were open to the air , two were covered with gauze , and two were tightly sealed . His hypothesis was supported when maggots developed in the uncovered jars , but no maggots appeared in either the gauze-covered or the tightly sealed jars . He concluded that maggots could only form when flies were allowed to lay eggs in the meat , and that the maggots were the offspring of flies , not the product of spontaneous generation .", "hl_sentences": "However , one of van Helmont ’ s contemporaries , Italian physician Francesco Redi ( 1626 – 1697 ) , performed an experiment in 1668 that was one of the first to refute the idea that maggots ( the larvae of flies ) spontaneously generate on meat left out in the open air .", "question": { "cloze_format": "The scientist that experimented with raw meat, maggots, and flies in an attempt to disprove the theory of spontaneous generation was ___.", "normal_format": "Which of the following scientists experimented with raw meat, maggots, and flies in an attempt to disprove the theory of spontaneous generation?", "question_choices": [ "Aristotle", "Lazzaro Spallanzani", "Antonie van Leeuwenhoek", "Francesco Redi" ], "question_id": "fs-id1172100953578", "question_text": "Which of the following scientists experimented with raw meat, maggots, and flies in an attempt to disprove the theory of spontaneous generation?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 0, "ans_text": "A" }, "bloom": null, "hl_context": "<hl> In the 1850s , two Polish scientists living in Germany pushed this idea further , culminating in what we recognize today as the modern cell theory . <hl> <hl> In 1852 , Robert Remak ( 1815 – 1865 ) , a prominent neurologist and embryologist , published convincing evidence that cells are derived from other cells as a result of cell division . <hl> However , this idea was questioned by many in the scientific community . Three years later , Rudolf Virchow ( 1821 – 1902 ) , a well-respected pathologist , published an editorial essay entitled “ Cellular Pathology , ” which popularized the concept of cell theory using the Latin phrase omnis cellula a cellula ( “ all cells arise from cells ” ) , which is essentially the second tenet of modern cell theory . 5 Given the similarity of Virchow ’ s work to Remak ’ s , there is some controversy as to which scientist should receive credit for articulating cell theory . See the following Eye on Ethics feature for more about this controversy . 5 M . Schultz . “ Rudolph Virchow . ” Emerging Infectious Diseases 14 no . 9 ( 2008 ): 1480 – 1481 . Despite Hooke ’ s early description of cells , their significance as the fundamental unit of life was not yet recognized . <hl> Nearly 200 years later , in 1838 , Matthias Schleiden ( 1804 – 1881 ) , a German botanist who made extensive microscopic observations of plant tissues , described them as being composed of cells . <hl> Visualizing plant cells was relatively easy because plant cells are clearly separated by their thick cell walls . Schleiden believed that cells formed through crystallization , rather than cell division . <hl> The English scientist Robert Hooke first used the term “ cells ” in 1665 to describe the small chambers within cork that he observed under a microscope of his own design . <hl> To Hooke , thin sections of cork resembled “ Honey-comb , ” or “ small Boxes or Bladders of Air . ” He noted that each “ Cavern , Bubble , or Cell ” was distinct from the others ( Figure 3.5 ) . At the time , Hooke was not aware that the cork cells were long dead and , therefore , lacked the internal structures found within living cells .", "hl_sentences": "In the 1850s , two Polish scientists living in Germany pushed this idea further , culminating in what we recognize today as the modern cell theory . In 1852 , Robert Remak ( 1815 – 1865 ) , a prominent neurologist and embryologist , published convincing evidence that cells are derived from other cells as a result of cell division . Nearly 200 years later , in 1838 , Matthias Schleiden ( 1804 – 1881 ) , a German botanist who made extensive microscopic observations of plant tissues , described them as being composed of cells . The English scientist Robert Hooke first used the term “ cells ” in 1665 to describe the small chambers within cork that he observed under a microscope of his own design .", "question": { "cloze_format": "The individual that did not contribute to the establishment of cell theory is ___ .", "normal_format": "Which of the following individuals did not contribute to the establishment of cell theory?", "question_choices": [ "Girolamo Fracastoro", "Matthias Schleiden", "Robert Remak", "Robert Hooke" ], "question_id": "fs-id1172100999760", "question_text": "Which of the following individuals did not contribute to the establishment of cell theory?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 2, "ans_text": "C" }, "bloom": null, "hl_context": "The large , complex organelles in which aerobic cellular respiration occurs in eukaryotic cells are called mitochondria ( Figure 3.49 ) . The term “ mitochondrion ” was first coined by German microbiologist Carl Benda in 1898 and was later connected with the process of respiration by Otto Warburg in 1913 . Scientists during the 1960s discovered that mitochondria have their own genome and 70S ribosomes . The mitochondrial genome was found to be bacterial , when it was sequenced in 1976 . <hl> These findings ultimately supported the endosymbiotic theory proposed by Lynn Margulis , which states that mitochondria originally arose through an endosymbiotic event in which a bacterium capable of aerobic cellular respiration was taken up by phagocytosis into a host cell and remained as a viable intracellular component . <hl> Wallin ’ s ideas regarding the endosymbiotic hypothesis were largely ignored for the next 50 years because scientists were unaware that these organelles contained their own DNA . However , with the discovery of mitochondrial and chloroplast DNA in the 1960s , the endosymbiotic hypothesis was resurrected . <hl> Lynn Margulis ( 1938 – 2011 ) , an American geneticist , published her ideas regarding the endosymbiotic hypothesis of the origins of mitochondria and chloroplasts in 1967 . <hl> 12 In the decade leading up to her publication , advances in microscopy had allowed scientists to differentiate prokaryotic cells from eukaryotic cells . In her publication , Margulis reviewed the literature and argued that the eukaryotic organelles such as mitochondria and chloroplasts are of prokaryotic origin . She presented a growing body of microscopic , genetic , molecular biology , fossil , and geological data to support her claims . 12 L . Sagan . “ On the Origin of Mitosing Cells . ” Journal of Theoretical Biology 14 no . 3 ( 1967 ): 225 – 274 .", "hl_sentences": "These findings ultimately supported the endosymbiotic theory proposed by Lynn Margulis , which states that mitochondria originally arose through an endosymbiotic event in which a bacterium capable of aerobic cellular respiration was taken up by phagocytosis into a host cell and remained as a viable intracellular component . Lynn Margulis ( 1938 – 2011 ) , an American geneticist , published her ideas regarding the endosymbiotic hypothesis of the origins of mitochondria and chloroplasts in 1967 .", "question": { "cloze_format": "___ 's proposal of the endosymbiotic theory of mitochondrial and chloroplast origin was ultimately accepted by the greater scientific community.", "normal_format": "Whose proposal of the endosymbiotic theory of mitochondrial and chloroplast origin was ultimately accepted by the greater scientific community?", "question_choices": [ "Rudolf Virchow", "Ignaz Semmelweis", "Lynn Margulis", "Theodor Schwann" ], "question_id": "fs-id1172100835261", "question_text": "Whose proposal of the endosymbiotic theory of mitochondrial and chloroplast origin was ultimately accepted by the greater scientific community?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 1, "ans_text": "B" }, "bloom": null, "hl_context": "<hl> A few years later , Robert Koch ( Figure 3.9 ) proposed a series of postulates ( Koch ’ s postulates ) based on the idea that the cause of a specific disease could be attributed to a specific microbe . <hl> Using these postulates , Koch and his colleagues were able to definitively identify the causative pathogens of specific diseases , including anthrax , tuberculosis , and cholera . Koch ’ s “ one microbe , one disease ” concept was the culmination of the 19th century ’ s paradigm shift away from miasma theory and toward the germ theory of disease . Koch ’ s postulates are discussed more thoroughly in How Pathogens Cause Disease .", "hl_sentences": "A few years later , Robert Koch ( Figure 3.9 ) proposed a series of postulates ( Koch ’ s postulates ) based on the idea that the cause of a specific disease could be attributed to a specific microbe .", "question": { "cloze_format": "___ developed a set of postulates for determining whether a particular disease is caused by a particular pathogen.", "normal_format": "Which of the following developed a set of postulates for determining whether a particular disease is caused by a particular pathogen?", "question_choices": [ "John Snow", "Robert Koch", "Joseph Lister", "Louis Pasteur" ], "question_id": "fs-id1172100596392", "question_text": "Which of the following developed a set of postulates for determining whether a particular disease is caused by a particular pathogen?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 0, "ans_text": "A" }, "bloom": null, "hl_context": "Gram-negative cells have a much thinner layer of peptidoglycan ( no more than about 4 nm thick 21 ) than gram-positive cells , and the overall structure of their cell envelope is more complex . <hl> In gram-negative cells , a gel-like matrix occupies the periplasmic space between the cell wall and the plasma membrane , and there is a second lipid bilayer called the outer membrane , which is external to the peptidoglycan layer ( Figure 3.26 ) . <hl> This outer membrane is attached to the peptidoglycan by murein lipoprotein . <hl> The outer leaflet of the outer membrane contains the molecule lipopolysaccharide ( LPS ) , which functions as an endotoxin in infections involving gram-negative bacteria , contributing to symptoms such as fever , hemorrhaging , and septic shock . <hl> Each LPS molecule is composed of Lipid A , a core polysaccharide , and an O side chain that is composed of sugar-like molecules that comprise the external face of the LPS ( Figure 3.28 ) . The composition of the O side chain varies between different species and strains of bacteria . Parts of the O side chain called antigens can be detected using serological or immunological tests to identify specific pathogenic strains like Escherichia coli O157 : H7 , a deadly strain of bacteria that causes bloody diarrhea and kidney failure . 21 L . Gana , S . Chena , G . J . Jensena . “ Molecular Organization of Gram-Negative Peptidoglycan . ” Proceedings of the National Academy of Sciences of the United States of America 105 no . 48 ( 2008 ): 18953 – 18957 .", "hl_sentences": "In gram-negative cells , a gel-like matrix occupies the periplasmic space between the cell wall and the plasma membrane , and there is a second lipid bilayer called the outer membrane , which is external to the peptidoglycan layer ( Figure 3.26 ) . The outer leaflet of the outer membrane contains the molecule lipopolysaccharide ( LPS ) , which functions as an endotoxin in infections involving gram-negative bacteria , contributing to symptoms such as fever , hemorrhaging , and septic shock .", "question": { "cloze_format": "The cell wall component that is unique to gram-negative cells is ___.", "normal_format": "Which of the following cell wall components is unique to gram-negative cells?", "question_choices": [ "lipopolysaccharide", "teichoic acid", "mycolic acid", "peptidoglycan" ], "question_id": "fs-id1172099600527", "question_text": "Which of the following cell wall components is unique to gram-negative cells?" }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 3, "ans_text": "D" }, "bloom": null, "hl_context": "Different types of motile bacteria exhibit different arrangements of flagella ( Figure 3.32 ) . A bacterium with a singular flagellum , typically located at one end of the cell ( polar ) , is said to have a monotrichous flagellum . An example of a monotrichously flagellated bacterial pathogen is Vibrio cholerae , the gram-negative bacterium that causes cholera . Cells with amphitrichous flagella have a flagellum or tufts of flagella at each end . An example is Spirillum minor , the cause of spirillary ( Asian ) rat-bite fever or sodoku . <hl> Cells with lophotrichous flagella have a tuft at one end of the cell . <hl> The gram-negative bacillus Pseudomonas aeruginosa , an opportunistic pathogen known for causing many infections , including “ swimmer ’ s ear ” and burn wound infections , has lophotrichous flagella . Flagella that cover the entire surface of a bacterial cell are called peritrichous flagella . The gram-negative bacterium E . coli shows a peritrichous arrangement of flagella .", "hl_sentences": "Cells with lophotrichous flagella have a tuft at one end of the cell .", "question": { "cloze_format": "___ is a term that refers to a bacterial cell having a single tuft of flagella at one end.", "normal_format": "Which of the following terms refers to a bacterial cell having a single tuft of flagella at one end?", "question_choices": [ "monotrichous", "amphitrichous", "peritrichous", "lophotrichous" ], "question_id": "fs-id1172101778290", "question_text": "Which of the following terms refers to a bacterial cell having a single tuft of flagella at one end?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 3, "ans_text": "D" }, "bloom": null, "hl_context": "<hl> The major component of bacterial cell walls is called peptidoglycan ( or murein ); it is only found in bacteria . <hl> Structurally , peptidoglycan resembles a layer of meshwork or fabric ( Figure 3.25 ) . Each layer is composed of long chains of alternating molecules of N-acetylglucosamine ( NAG ) and N-acetylmuramic acid ( NAM ) . The structure of the long chains has significant two-dimensional tensile strength due to the formation of peptide bridges that connect NAG and NAM within each peptidoglycan layer . In gram-negative bacteria , tetrapeptide chains extending from each NAM unit are directly cross-linked , whereas in gram-positive bacteria , these tetrapeptide chains are linked by pentaglycine cross-bridges . Peptidoglycan subunits are made inside of the bacterial cell and then exported and assembled in layers , giving the cell its shape .", "hl_sentences": "The major component of bacterial cell walls is called peptidoglycan ( or murein ); it is only found in bacteria .", "question": { "cloze_format": "Bacterial cell walls are primarily composed of ___.", "normal_format": "Bacterial cell walls are primarily composed of which of the following?", "question_choices": [ "phospholipid", "protein", "carbohydrate", "peptidoglycan" ], "question_id": "fs-id1172097146064", "question_text": "Bacterial cell walls are primarily composed of which of the following?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 3, "ans_text": "D" }, "bloom": null, "hl_context": "<hl> Christian de Duve is also credited with the discovery of peroxisomes , membrane-bound organelles that are not part of the endomembrane system ( Figure 3.43 ) . <hl> Peroxisomes form independently in the cytoplasm from the synthesis of peroxin proteins by free ribosomes and the incorporation of these peroxin proteins into existing peroxisomes . Growing peroxisomes then divide by a process similar to binary fission . The endomembrane system , unique to eukaryotic cells , is a series of membranous tubules , sacs , and flattened disks that synthesize many cell components and move materials around within the cell ( Figure 3.40 ) . Because of their larger cell size , eukaryotic cells require this system to transport materials that cannot be dispersed by diffusion alone . <hl> The endomembrane system comprises several organelles and connections between them , including the endoplasmic reticulum , Golgi apparatus , lysosomes , and vesicles . <hl>", "hl_sentences": "Christian de Duve is also credited with the discovery of peroxisomes , membrane-bound organelles that are not part of the endomembrane system ( Figure 3.43 ) . The endomembrane system comprises several organelles and connections between them , including the endoplasmic reticulum , Golgi apparatus , lysosomes , and vesicles .", "question": { "cloze_format": "The organelle that is not part of the endomembrane system is ___.", "normal_format": "Which of the following organelles is not part of the endomembrane system?", "question_choices": [ "endoplasmic reticulum", "Golgi apparatus", "lysosome", "peroxisome" ], "question_id": "fs-id1172098268292", "question_text": "Which of the following organelles is not part of the endomembrane system?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 1, "ans_text": "B" }, "bloom": null, "hl_context": "<hl> Intermediate filaments ( Figure 3.46 ) are a diverse group of cytoskeletal filaments that act as cables within the cell . <hl> They are termed “ intermediate ” because their 10 - nm diameter is thicker than that of actin but thinner than that of microtubules . 26 They are composed of several strands of polymerized subunits that , in turn , are made up of a wide variety of monomers . <hl> Intermediate filaments tend to be more permanent in the cell and maintain the position of the nucleus . <hl> <hl> They also form the nuclear lamina ( lining or layer ) just inside the nuclear envelope . <hl> Additionally , intermediate filaments play a role in anchoring cells together in animal tissues . The intermediate filament protein desmin is found in desmosomes , the protein structures that join muscle cells together and help them resist external physical forces . The intermediate filament protein keratin is a structural protein found in hair , skin , and nails . 26 E . Fuchs , D . W . Cleveland . “ A Structural Scaffolding of Intermediate Filaments in Health and Disease . ” Science 279 no . 5350 ( 1998 ): 514 – 519 . The nucleus is bound by a complex nuclear membrane , often called the nuclear envelope , that consists of two distinct lipid bilayers that are contiguous with each other ( Figure 3.38 ) . Despite these connections between the inner and outer membranes , each membrane contains unique lipids and proteins on its inner and outer surfaces . The nuclear envelope contains nuclear pores , which are large , rosette-shaped protein complexes that control the movement of materials into and out of the nucleus . <hl> The overall shape of the nucleus is determined by the nuclear lamina , a meshwork of intermediate filaments found just inside the nuclear envelope membranes . <hl> Outside the nucleus , additional intermediate filaments form a looser mesh and serve to anchor the nucleus in position within the cell .", "hl_sentences": "Intermediate filaments ( Figure 3.46 ) are a diverse group of cytoskeletal filaments that act as cables within the cell . Intermediate filaments tend to be more permanent in the cell and maintain the position of the nucleus . They also form the nuclear lamina ( lining or layer ) just inside the nuclear envelope . The overall shape of the nucleus is determined by the nuclear lamina , a meshwork of intermediate filaments found just inside the nuclear envelope membranes .", "question": { "cloze_format": "___ are a type of cytoskeletal fiber that is important in the formation of the nuclear lamina.", "normal_format": "Which type of cytoskeletal fiber is important in the formation of the nuclear lamina?", "question_choices": [ "microfilaments", "intermediate filaments", "microtubules", "fibronectin" ], "question_id": "fs-id1172100922415", "question_text": "Which type of cytoskeletal fiber is important in the formation of the nuclear lamina?" }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 2, "ans_text": "C" }, "bloom": null, "hl_context": "<hl> Enzymes in the Golgi apparatus modify lipids and proteins transported from the ER to the Golgi , often adding carbohydrate components to them , producing glycolipids , glycoproteins , or proteoglycans . <hl> Glycolipids and glycoproteins are often inserted into the plasma membrane and are important for signal recognition by other cells or infectious particles . Different types of cells can be distinguished from one another by the structure and arrangement of the glycolipids and glycoproteins contained in their plasma membranes . These glycolipids and glycoproteins commonly also serve as cell surface receptors .", "hl_sentences": "Enzymes in the Golgi apparatus modify lipids and proteins transported from the ER to the Golgi , often adding carbohydrate components to them , producing glycolipids , glycoproteins , or proteoglycans .", "question": { "cloze_format": "Sugar groups may be added to proteins in the ___.", "normal_format": "Sugar groups may be added to proteins in which of the following?", "question_choices": [ "smooth endoplasmic reticulum", "rough endoplasmic reticulum", "Golgi apparatus", "lysosome" ], "question_id": "fs-id1172100925718", "question_text": "Sugar groups may be added to proteins in which of the following?" }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 3, "ans_text": "D" }, "bloom": null, "hl_context": "<hl> Each mitochondrion has two lipid membranes . <hl> <hl> The outer membrane is a remnant of the original host cell ’ s membrane structures . <hl> <hl> The inner membrane was derived from the bacterial plasma membrane . <hl> The electron transport chain for aerobic respiration uses integral proteins embedded in the inner membrane . <hl> The mitochondrial matrix , corresponding to the location of the original bacterium ’ s cytoplasm , is the current location of many metabolic enzymes . <hl> <hl> It also contains mitochondrial DNA and 70S ribosomes . <hl> Invaginations of the inner membrane , called cristae , evolved to increase surface area for the location of biochemical reactions . The folding patterns of the cristae differ among various types of eukaryotic cells and are used to distinguish different eukaryotic organisms from each other .", "hl_sentences": "Each mitochondrion has two lipid membranes . The outer membrane is a remnant of the original host cell ’ s membrane structures . The inner membrane was derived from the bacterial plasma membrane . The mitochondrial matrix , corresponding to the location of the original bacterium ’ s cytoplasm , is the current location of many metabolic enzymes . It also contains mitochondrial DNA and 70S ribosomes .", "question": { "cloze_format": "The structure of a eukaryotic cell that is not likely derived from endosymbiotic bacterium is the ___.", "normal_format": "Which of the following structures of a eukaryotic cell is not likely derived from endosymbiotic bacterium?", "question_choices": [ "mitochondrial DNA", "mitochondrial ribosomes", "inner membrane", "outer membrane" ], "question_id": "fs-id1172098530560", "question_text": "Which of the following structures of a eukaryotic cell is not likely derived from endosymbiotic bacterium?" }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 1, "ans_text": "B" }, "bloom": null, "hl_context": "The processes of simple diffusion , facilitated diffusion , and active transport are used in both eukaryotic and prokaryotic cells . However , eukaryotic cells also have the unique ability to perform various types of endocytosis , the uptake of matter through plasma membrane invagination and vacuole / vesicle formation ( Figure 3.52 ) . A type of endocytosis involving the engulfment of large particles through membrane invagination is called phagocytosis , which means “ cell eating . ” In phagocytosis , particles ( or other cells ) are enclosed in a pocket within the membrane , which then pinches off from the membrane to form a vacuole that completely surrounds the particle . <hl> Another type of endocytosis is called pinocytosis , which means “ cell drinking . ” In pinocytosis , small , dissolved materials and liquids are taken into the cell through small vesicles . <hl> Saprophytic fungi , for example , obtain their nutrients from dead and decaying matter largely through pinocytosis .", "hl_sentences": "Another type of endocytosis is called pinocytosis , which means “ cell drinking . ” In pinocytosis , small , dissolved materials and liquids are taken into the cell through small vesicles .", "question": { "cloze_format": "___ is a type of nutrient uptake that involves the engulfment of small dissolved molecules into vesicles.", "normal_format": "Which type of nutrient uptake involves the engulfment of small dissolved molecules into vesicles?", "question_choices": [ "active transport", "pinocytosis", "receptor-mediated endocytosis", "facilitated diffusion" ], "question_id": "fs-id1172098560339", "question_text": "Which type of nutrient uptake involves the engulfment of small dissolved molecules into vesicles?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 0, "ans_text": "A" }, "bloom": null, "hl_context": "In addition , microtubules are involved in cell division , forming the mitotic spindle that serves to separate chromosomes during mitosis and meiosis . The mitotic spindle is produced by two centrosomes , which are essentially microtubule-organizing centers , at opposite ends of the cell . <hl> Each centrosome is composed of a pair of centrioles positioned at right angles to each other , and each centriole is an array of nine parallel microtubules arranged in triplets ( Figure 3.48 ) . <hl> Microtubules ( Figure 3.47 ) are a third type of cytoskeletal fiber composed of tubulin dimers ( α tubulin and β tubulin ) . These form hollow tubes 23 nm in diameter that are used as girders within the cytoskeleton . 27 Like microfilaments , microtubules are dynamic and have the ability to rapidly assemble and disassemble . Microtubules also work with motor proteins ( such as dynein and kinesin ) to move organelles and vesicles around within the cytoplasm . <hl> Additionally , microtubules are the main components of eukaryotic flagella and cilia , composing both the filament and the basal body components ( Figure 3.54 ) . <hl> 27 E . Fuchs , D . W . Cleveland . “ A Structural Scaffolding of Intermediate Filaments in Health and Disease . ” Science 279 no . 5350 ( 1998 ): 514 – 519 .", "hl_sentences": "Each centrosome is composed of a pair of centrioles positioned at right angles to each other , and each centriole is an array of nine parallel microtubules arranged in triplets ( Figure 3.48 ) . Additionally , microtubules are the main components of eukaryotic flagella and cilia , composing both the filament and the basal body components ( Figure 3.54 ) .", "question": { "cloze_format": "___ is not composed of microtubules.", "normal_format": "Which of the following is not composed of microtubules?", "question_choices": [ "desmosomes", "centrioles", "eukaryotic flagella", "eukaryotic cilia" ], "question_id": "fs-id1172098387586", "question_text": "Which of the following is not composed of microtubules?" }, "references_are_paraphrase": null } ]
3
3.1 Spontaneous Generation Learning Objectives Explain the theory of spontaneous generation and why people once accepted it as an explanation for the existence of certain types of organisms Explain how certain individuals (van Helmont, Redi, Needham, Spallanzani, and Pasteur) tried to prove or disprove spontaneous generation Clinical Focus Part 1 Barbara is a 19-year-old college student living in the dormitory. In January, she came down with a sore throat, headache, mild fever, chills, and a violent but unproductive (i.e., no mucus) cough. To treat these symptoms, Barbara began taking an over-the-counter cold medication, which did not seem to work. In fact, over the next few days, while some of Barbara’s symptoms began to resolve, her cough and fever persisted, and she felt very tired and weak. What types of respiratory disease may be responsible? Jump to the next Clinical Focus box Humans have been asking for millennia: Where does new life come from? Religion, philosophy, and science have all wrestled with this question. One of the oldest explanations was the theory of spontaneous generation, which can be traced back to the ancient Greeks and was widely accepted through the Middle Ages. The Theory of Spontaneous Generation The Greek philosopher Aristotle (384–322 BC) was one of the earliest recorded scholars to articulate the theory of spontaneous generation , the notion that life can arise from nonliving matter. Aristotle proposed that life arose from nonliving material if the material contained pneuma (“vital heat”). As evidence, he noted several instances of the appearance of animals from environments previously devoid of such animals, such as the seemingly sudden appearance of fish in a new puddle of water. 1 1 K. Zwier. “Aristotle on Spontaneous Generation.” http://www.sju.edu/int/academics/cas/resources/gppc/pdf/Karen%20R.%20Zwier.pdf This theory persisted into the 17th century, when scientists undertook additional experimentation to support or disprove it. By this time, the proponents of the theory cited how frogs simply seem to appear along the muddy banks of the Nile River in Egypt during the annual flooding. Others observed that mice simply appeared among grain stored in barns with thatched roofs. When the roof leaked and the grain molded, mice appeared. Jan Baptista van Helmont , a 17th century Flemish scientist, proposed that mice could arise from rags and wheat kernels left in an open container for 3 weeks. In reality, such habitats provided ideal food sources and shelter for mouse populations to flourish. However, one of van Helmont’s contemporaries, Italian physician Francesco Redi (1626–1697), performed an experiment in 1668 that was one of the first to refute the idea that maggots (the larvae of flies) spontaneously generate on meat left out in the open air. He predicted that preventing flies from having direct contact with the meat would also prevent the appearance of maggots. Redi left meat in each of six containers ( Figure 3.2 ). Two were open to the air, two were covered with gauze, and two were tightly sealed. His hypothesis was supported when maggots developed in the uncovered jars, but no maggots appeared in either the gauze-covered or the tightly sealed jars. He concluded that maggots could only form when flies were allowed to lay eggs in the meat, and that the maggots were the offspring of flies, not the product of spontaneous generation. In 1745, John Needham (1713–1781) published a report of his own experiments, in which he briefly boiled broth infused with plant or animal matter, hoping to kill all preexisting microbes. 2 He then sealed the flasks. After a few days, Needham observed that the broth had become cloudy and a single drop contained numerous microscopic creatures. He argued that the new microbes must have arisen spontaneously. In reality, however, he likely did not boil the broth enough to kill all preexisting microbes. 2 E. Capanna. “Lazzaro Spallanzani: At the Roots of Modern Biology.” Journal of Experimental Zoology 285 no. 3 (1999):178–196. Lazzaro Spallanzani (1729–1799) did not agree with Needham’s conclusions, however, and performed hundreds of carefully executed experiments using heated broth. 3 As in Needham’s experiment, broth in sealed jars and unsealed jars was infused with plant and animal matter. Spallanzani’s results contradicted the findings of Needham: Heated but sealed flasks remained clear, without any signs of spontaneous growth, unless the flasks were subsequently opened to the air. This suggested that microbes were introduced into these flasks from the air. In response to Spallanzani’s findings, Needham argued that life originates from a “life force” that was destroyed during Spallanzani’s extended boiling. Any subsequent sealing of the flasks then prevented new life force from entering and causing spontaneous generation ( Figure 3.3 ). 3 R. Mancini, M. Nigro, G. Ippolito. “Lazzaro Spallanzani and His Refutation of the Theory of Spontaneous Generation.” Le Infezioni in Medicina 15 no. 3 (2007):199–206. Check Your Understanding Describe the theory of spontaneous generation and some of the arguments used to support it. Explain how the experiments of Redi and Spallanzani challenged the theory of spontaneous generation. Disproving Spontaneous Generation The debate over spontaneous generation continued well into the 19th century, with scientists serving as proponents of both sides. To settle the debate, the Paris Academy of Sciences offered a prize for resolution of the problem. Louis Pasteur , a prominent French chemist who had been studying microbial fermentation and the causes of wine spoilage, accepted the challenge. In 1858, Pasteur filtered air through a gun-cotton filter and, upon microscopic examination of the cotton, found it full of microorganisms, suggesting that the exposure of a broth to air was not introducing a “life force” to the broth but rather airborne microorganisms. Later, Pasteur made a series of flasks with long, twisted necks (“swan-neck” flasks), in which he boiled broth to sterilize it ( Figure 3.4 ). His design allowed air inside the flasks to be exchanged with air from the outside, but prevented the introduction of any airborne microorganisms, which would get caught in the twists and bends of the flasks’ necks. If a life force besides the airborne microorganisms were responsible for microbial growth within the sterilized flasks, it would have access to the broth, whereas the microorganisms would not. He correctly predicted that sterilized broth in his swan-neck flasks would remain sterile as long as the swan necks remained intact. However, should the necks be broken, microorganisms would be introduced, contaminating the flasks and allowing microbial growth within the broth. Pasteur’s set of experiments irrefutably disproved the theory of spontaneous generation and earned him the prestigious Alhumbert Prize from the Paris Academy of Sciences in 1862. In a subsequent lecture in 1864, Pasteur articulated “ Omne vivum ex vivo ” (“Life only comes from life”). In this lecture, Pasteur recounted his famous swan-neck flask experiment, stating that “…life is a germ and a germ is life. Never will the doctrine of spontaneous generation recover from the mortal blow of this simple experiment.” 4 To Pasteur’s credit, it never has. 4 R. Vallery-Radot. The Life of Pasteur , trans. R.L. Devonshire. New York: McClure, Phillips and Co, 1902, 1:142. Check Your Understanding How did Pasteur’s experimental design allow air, but not microbes, to enter, and why was this important? What was the control group in Pasteur’s experiment and what did it show? 3.2 Foundations of Modern Cell Theory Learning Objectives Explain the key points of cell theory and the individual contributions of Hooke, Schleiden, Schwann, Remak, and Virchow Explain the key points of endosymbiotic theory and cite the evidence that supports this concept Explain the contributions of Semmelweis, Snow, Pasteur, Lister, and Koch to the development of germ theory While some scientists were arguing over the theory of spontaneous generation, other scientists were making discoveries leading to a better understanding of what we now call the cell theory . Modern cell theory has two basic tenets: All cells only come from other cells (the principle of biogenesis). Cells are the fundamental units of organisms. Today, these tenets are fundamental to our understanding of life on earth. However, modern cell theory grew out of the collective work of many scientists. The Origins of Cell Theory The English scientist Robert Hooke first used the term “cells” in 1665 to describe the small chambers within cork that he observed under a microscope of his own design. To Hooke, thin sections of cork resembled “Honey-comb,” or “small Boxes or Bladders of Air.” He noted that each “Cavern, Bubble, or Cell” was distinct from the others ( Figure 3.5 ). At the time, Hooke was not aware that the cork cells were long dead and, therefore, lacked the internal structures found within living cells. Despite Hooke’s early description of cells, their significance as the fundamental unit of life was not yet recognized. Nearly 200 years later, in 1838, Matthias Schleiden (1804–1881), a German botanist who made extensive microscopic observations of plant tissues, described them as being composed of cells. Visualizing plant cells was relatively easy because plant cells are clearly separated by their thick cell walls. Schleiden believed that cells formed through crystallization, rather than cell division. Theodor Schwann (1810–1882), a noted German physiologist, made similar microscopic observations of animal tissue. In 1839, after a conversation with Schleiden, Schwann realized that similarities existed between plant and animal tissues. This laid the foundation for the idea that cells are the fundamental components of plants and animals. In the 1850s, two Polish scientists living in Germany pushed this idea further, culminating in what we recognize today as the modern cell theory. In 1852, Robert Remak (1815–1865), a prominent neurologist and embryologist, published convincing evidence that cells are derived from other cells as a result of cell division. However, this idea was questioned by many in the scientific community. Three years later, Rudolf Virchow (1821–1902), a well-respected pathologist, published an editorial essay entitled “Cellular Pathology,” which popularized the concept of cell theory using the Latin phrase omnis cellula a cellula (“all cells arise from cells”), which is essentially the second tenet of modern cell theory. 5 Given the similarity of Virchow’s work to Remak’s, there is some controversy as to which scientist should receive credit for articulating cell theory. See the following Eye on Ethics feature for more about this controversy. 5 M. Schultz. “Rudolph Virchow.” Emerging Infectious Diseases 14 no. 9 (2008):1480–1481. Eye on Ethics Science and Plagiarism Rudolf Virchow, a prominent, Polish-born, German scientist, is often remembered as the “Father of Pathology.” Well known for innovative approaches, he was one of the first to determine the causes of various diseases by examining their effects on tissues and organs. He was also among the first to use animals in his research and, as a result of his work, he was the first to name numerous diseases and created many other medical terms. Over the course of his career, he published more than 2,000 papers and headed various important medical facilities, including the Charité – Universitätsmedizin Berlin, a prominent Berlin hospital and medical school. But he is, perhaps, best remembered for his 1855 editorial essay titled “Cellular Pathology,” published in Archiv für Pathologische Anatomie und Physiologie , a journal that Virchow himself cofounded and still exists today. Despite his significant scientific legacy, there is some controversy regarding this essay, in which Virchow proposed the central tenet of modern cell theory—that all cells arise from other cells. Robert Remak, a former colleague who worked in the same laboratory as Virchow at the University of Berlin, had published the same idea 3 years before. Though it appears Virchow was familiar with Remak’s work, he neglected to credit Remak’s ideas in his essay. When Remak wrote a letter to Virchow pointing out similarities between Virchow’s ideas and his own, Virchow was dismissive. In 1858, in the preface to one of his books, Virchow wrote that his 1855 publication was just an editorial piece, not a scientific paper, and thus there was no need to cite Remak’s work. By today’s standards, Virchow’s editorial piece would certainly be considered an act of plagiarism, since he presented Remak’s ideas as his own. However, in the 19th century, standards for academic integrity were much less clear. Virchow’s strong reputation, coupled with the fact that Remak was a Jew in a somewhat anti-Semitic political climate, shielded him from any significant repercussions. Today, the process of peer review and the ease of access to the scientific literature help discourage plagiarism. Although scientists are still motivated to publish original ideas that advance scientific knowledge, those who would consider plagiarizing are well aware of the serious consequences. In academia, plagiarism represents the theft of both individual thought and research—an offense that can destroy reputations and end careers. 6 7 8 9 6 B. Kisch. “Forgotten Leaders in Modern Medicine, Valentin, Gouby, Remak, Auerbach.” Transactions of the American Philosophical Society 44 (1954):139–317. 7 H. Harris. The Birth of the Cell . New Haven, CT: Yale University Press, 2000:133. 8 C. Webster (ed.). Biology, Medicine and Society 1840-1940 . Cambridge, UK; Cambridge University Press, 1981:118–119. 9 C. Zuchora-Walske. Key Discoveries in Life Science . Minneapolis, MN: Lerner Publishing, 2015:12–13. Check Your Understanding What are the key points of the cell theory? What contributions did Rudolf Virchow and Robert Remak make to the development of the cell theory? Endosymbiotic Theory As scientists were making progress toward understanding the role of cells in plant and animal tissues, others were examining the structures within the cells themselves. In 1831, Scottish botanist Robert Brown (1773–1858) was the first to describe observations of nuclei, which he observed in plant cells. Then, in the early 1880s, German botanist Andreas Schimper (1856–1901) was the first to describe the chloroplasts of plant cells, identifying their role in starch formation during photosynthesis and noting that they divided independent of the nucleus. Based upon the chloroplasts’ ability to reproduce independently, Russian botanist Konstantin Mereschkowski (1855–1921) suggested in 1905 that chloroplasts may have originated from ancestral photosynthetic bacteria living symbiotically inside a eukaryotic cell. He proposed a similar origin for the nucleus of plant cells. This was the first articulation of the endosymbiotic hypothesis , and would explain how eukaryotic cells evolved from ancestral bacteria. Mereschkowski’s endosymbiotic hypothesis was furthered by American anatomist Ivan Wallin (1883–1969), who began to experimentally examine the similarities between mitochondria, chloroplasts, and bacteria—in other words, to put the endosymbiotic hypothesis to the test using objective investigation. Wallin published a series of papers in the 1920s supporting the endosymbiotic hypothesis, including a 1926 publication co-authored with Mereschkowski. Wallin claimed he could culture mitochondria outside of their eukaryotic host cells. Many scientists dismissed his cultures of mitochondria as resulting from bacterial contamination. Modern genome sequencing work supports the dissenting scientists by showing that much of the genome of mitochondria had been transferred to the host cell’s nucleus, preventing the mitochondria from being able to live on their own. 10 11 10 T. Embley, W. Martin. “Eukaryotic Evolution, Changes, and Challenges.” Nature Vol. 440 (2006):623–630. 11 O.G. Berg, C.G. Kurland. “Why Mitochondrial Genes Are Most Often Found in Nuclei.” Molecular Biology and Evolution 17 no. 6 (2000):951–961. Wallin’s ideas regarding the endosymbiotic hypothesis were largely ignored for the next 50 years because scientists were unaware that these organelles contained their own DNA. However, with the discovery of mitochondrial and chloroplast DNA in the 1960s, the endosymbiotic hypothesis was resurrected. Lynn Margulis (1938–2011), an American geneticist, published her ideas regarding the endosymbiotic hypothesis of the origins of mitochondria and chloroplasts in 1967. 12 In the decade leading up to her publication, advances in microscopy had allowed scientists to differentiate prokaryotic cells from eukaryotic cells. In her publication, Margulis reviewed the literature and argued that the eukaryotic organelles such as mitochondria and chloroplasts are of prokaryotic origin. She presented a growing body of microscopic, genetic, molecular biology, fossil, and geological data to support her claims. 12 L. Sagan. “On the Origin of Mitosing Cells.” Journal of Theoretical Biology 14 no. 3 (1967):225–274. Again, this hypothesis was not initially popular, but mounting genetic evidence due to the advent of DNA sequencing supported the endosymbiotic theory , which is now defined as the theory that mitochondria and chloroplasts arose as a result of prokaryotic cells establishing a symbiotic relationship within a eukaryotic host ( Figure 3.7 ). With Margulis’ initial endosymbiotic theory gaining wide acceptance, she expanded on the theory in her 1981 book Symbiosis in Cell Evolution . In it, she explains how endosymbiosis is a major driving factor in the evolution of organisms. More recent genetic sequencing and phylogenetic analysis show that mitochondrial DNA and chloroplast DNA are highly related to their bacterial counterparts, both in DNA sequence and chromosome structure. However, mitochondrial DNA and chloroplast DNA are reduced compared with nuclear DNA because many of the genes have moved from the organelles into the host cell’s nucleus. Additionally, mitochondrial and chloroplast ribosomes are structurally similar to bacterial ribosomes, rather than to the eukaryotic ribosomes of their hosts. Last, the binary fission of these organelles strongly resembles the binary fission of bacteria, as compared with mitosis performed by eukaryotic cells. Since Margulis’ original proposal, scientists have observed several examples of bacterial endosymbionts in modern-day eukaryotic cells. Examples include the endosymbiotic bacteria found within the guts of certain insects, such as cockroaches, 13 and photosynthetic bacteria-like organelles found in protists. 14 13 A.E. Douglas. “The Microbial Dimension in Insect Nutritional Ecology.” Functional Ecology 23 (2009):38–47. 14 J.M. Jaynes, L.P. Vernon. “The Cyanelle of Cyanophora paradoxa : Almost a Cyanobacterial Chloroplast.” Trends in Biochemical Sciences 7 no. 1 (1982):22–24. Check Your Understanding What does the modern endosymbiotic theory state? What evidence supports the endosymbiotic theory? The Germ Theory of Disease Prior to the discovery of microbes during the 17th century, other theories circulated about the origins of disease. For example, the ancient Greeks proposed the miasma theory , which held that disease originated from particles emanating from decomposing matter, such as that in sewage or cesspits. Such particles infected humans in close proximity to the rotting material. Diseases including the Black Death, which ravaged Europe’s population during the Middle Ages, were thought to have originated in this way. In 1546, Italian physician Girolamo Fracastoro proposed, in his essay De Contagione et Contagiosis Morbis , that seed-like spores may be transferred between individuals through direct contact, exposure to contaminated clothing, or through the air. We now recognize Fracastoro as an early proponent of the germ theory of disease , which states that diseases may result from microbial infection. However, in the 16th century, Fracastoro’s ideas were not widely accepted and would be largely forgotten until the 19th century. In 1847, Hungarian obstetrician Ignaz Semmelweis ( Figure 3.8 ) observed that mothers who gave birth in hospital wards staffed by physicians and medical students were more likely to suffer and die from puerperal fever after childbirth (10%–20% mortality rate) than were mothers in wards staffed by midwives (1% mortality rate). Semmelweis observed medical students performing autopsies and then subsequently carrying out vaginal examinations on living patients without washing their hands in between. He suspected that the students carried disease from the autopsies to the patients they examined. His suspicions were supported by the untimely death of a friend, a physician who contracted a fatal wound infection after a postmortem examination of a woman who had died of a puerperal infection. The dead physician’s wound had been caused by a scalpel used during the examination, and his subsequent illness and death closely paralleled that of the dead patient. Although Semmelweis did not know the true cause of puerperal fever, he proposed that physicians were somehow transferring the causative agent to their patients. He suggested that the number of puerperal fever cases could be reduced if physicians and medical students simply washed their hands with chlorinated lime water before and after examining every patient. When this practice was implemented, the maternal mortality rate in mothers cared for by physicians dropped to the same 1% mortality rate observed among mothers cared for by midwives. This demonstrated that handwashing was a very effective method for preventing disease transmission. Despite this great success, many discounted Semmelweis’s work at the time, and physicians were slow to adopt the simple procedure of handwashing to prevent infections in their patients because it contradicted established norms for that time period. Around the same time Semmelweis was promoting handwashing, in 1848, British physician John Snow conducted studies to track the source of cholera outbreaks in London. By tracing the outbreaks to two specific water sources, both of which were contaminated by sewage, Snow ultimately demonstrated that cholera bacteria were transmitted via drinking water. Snow’s work is influential in that it represents the first known epidemiological study, and it resulted in the first known public health response to an epidemic. The work of both Semmelweis and Snow clearly refuted the prevailing miasma theory of the day, showing that disease is not only transmitted through the air but also through contaminated items. Although the work of Semmelweis and Snow successfully showed the role of sanitation in preventing infectious disease, the cause of disease was not fully understood. The subsequent work of Louis Pasteur , Robert Koch , and Joseph Lister would further substantiate the germ theory of disease. While studying the causes of beer and wine spoilage in 1856, Pasteur discovered properties of fermentation by microorganisms. He had demonstrated with his swan-neck flask experiments ( Figure 3.4 ) that airborne microbes, not spontaneous generation, were the cause of food spoilage, and he suggested that if microbes were responsible for food spoilage and fermentation, they could also be responsible for causing infection. This was the foundation for the germ theory of disease. Meanwhile, British surgeon Joseph Lister ( Figure 3.9 ) was trying to determine the causes of postsurgical infections. Many physicians did not give credence to the idea that microbes on their hands, on their clothes, or in the air could infect patients’ surgical wounds, despite the fact that 50% of surgical patients, on average, were dying of postsurgical infections. 15 Lister, however, was familiar with the work of Semmelweis and Pasteur; therefore, he insisted on handwashing and extreme cleanliness during surgery. In 1867, to further decrease the incidence of postsurgical wound infections, Lister began using carbolic acid (phenol) spray disinfectant/antiseptic during surgery. His extremely successful efforts to reduce postsurgical infection caused his techniques to become a standard medical practice. 15 Alexander, J. Wesley. “The Contributions of Infection Control to a Century of Progress” Annals of Surgery 201:423-428, 1985. A few years later, Robert Koch ( Figure 3.9 ) proposed a series of postulates (Koch’s postulates) based on the idea that the cause of a specific disease could be attributed to a specific microbe. Using these postulates, Koch and his colleagues were able to definitively identify the causative pathogens of specific diseases, including anthrax, tuberculosis, and cholera. Koch’s “one microbe, one disease” concept was the culmination of the 19th century’s paradigm shift away from miasma theory and toward the germ theory of disease. Koch’s postulates are discussed more thoroughly in How Pathogens Cause Disease . Check Your Understanding Compare and contrast the miasma theory of disease with the germ theory of disease. How did Joseph Lister’s work contribute to the debate between the miasma theory and germ theory and how did this increase the success of medical procedures? Clinical Focus Part 2 After suffering a fever, congestion, cough, and increasing aches and pains for several days, Barbara suspects that she has a case of the flu. She decides to visit the health center at her university. The PA tells Barbara that her symptoms could be due to a range of diseases, such as influenza, bronchitis, pneumonia, or tuberculosis. During her physical examination, the PA notes that Barbara’s heart rate is slightly elevated. Using a pulse oximeter, a small device that clips on her finger, he finds that Barbara has hypoxemia—a lower-than-normal level of oxygen in the blood. Using a stethoscope, the PA listens for abnormal sounds made by Barbara’s heart, lungs, and digestive system. As Barbara breathes, the PA hears a crackling sound and notes a slight shortness of breath. He collects a sputum sample, noting the greenish color of the mucus, and orders a chest radiograph, which shows a “shadow” in the left lung. All of these signs are suggestive of pneumonia , a condition in which the lungs fill with mucus ( Figure 3.10 ). What kinds of infectious agents are known to cause pneumonia? Jump to the next Clinical Focus box. Go back to the previous Clinical Focus box. 3.3 Unique Characteristics of Prokaryotic Cells Learning Objectives Explain the distinguishing characteristics of prokaryotic cells Describe common cell morphologies and cellular arrangements typical of prokaryotic cells and explain how cells maintain their morphology Describe internal and external structures of prokaryotic cells in terms of their physical structure, chemical structure, and function Compare the distinguishing characteristics of bacterial and archaeal cells Cell theory states that the cell is the fundamental unit of life. However, cells vary significantly in size, shape, structure, and function. At the simplest level of construction, all cells possess a few fundamental components. These include cytoplasm (a gel-like substance composed of water and dissolved chemicals needed for growth), which is contained within a plasma membrane (also called a cell membrane or cytoplasmic membrane); one or more chromosomes, which contain the genetic blueprints of the cell; and ribosomes , organelles used for the production of proteins. Beyond these basic components, cells can vary greatly between organisms, and even within the same multicellular organism. The two largest categories of cells— prokaryotic cells and eukaryotic cells —are defined by major differences in several cell structures. Prokaryotic cells lack a nucleus surrounded by a complex nuclear membrane and generally have a single, circular chromosome located in a nucleoid. Eukaryotic cells have a nucleus surrounded by a complex nuclear membrane that contains multiple, rod-shaped chromosomes. 16 16 Y.-H.M. Chan, W.F. Marshall. “Scaling Properties of Cell and Organelle Size.” Organogenesis 6 no. 2 (2010):88–96. All plant cells and animal cells are eukaryotic. Some microorganisms are composed of prokaryotic cells, whereas others are composed of eukaryotic cells. Prokaryotic microorganisms are classified within the domains Archaea and Bacteria, whereas eukaryotic organisms are classified within the domain Eukarya. The structures inside a cell are analogous to the organs inside a human body, with unique structures suited to specific functions. Some of the structures found in prokaryotic cells are similar to those found in some eukaryotic cells; others are unique to prokaryotes. Although there are some exceptions, eukaryotic cells tend to be larger than prokaryotic cells. The comparatively larger size of eukaryotic cells dictates the need to compartmentalize various chemical processes within different areas of the cell, using complex membrane-bound organelles. In contrast, prokaryotic cells generally lack membrane-bound organelles; however, they often contain inclusions that compartmentalize their cytoplasm. Figure 3.12 illustrates structures typically associated with prokaryotic cells. These structures are described in more detail in the next section. Common Cell Morphologies and Arrangements Individual cells of a particular prokaryotic organism are typically similar in shape, or cell morphology . Although thousands of prokaryotic organisms have been identified, only a handful of cell morphologies are commonly seen microscopically. Figure 3.13 names and illustrates cell morphologies commonly found in prokaryotic cells. In addition to cellular shape, prokaryotic cells of the same species may group together in certain distinctive arrangements depending on the plane of cell division. Some common arrangements are shown in Figure 3.14 . In most prokaryotic cells, morphology is maintained by the cell wall in combination with cytoskeletal elements. The cell wall is a structure found in most prokaryotes and some eukaryotes; it envelopes the cell membrane, protecting the cell from changes in osmotic pressure ( Figure 3.15 ). Osmotic pressure occurs because of differences in the concentration of solutes on opposing sides of a semipermeable membrane. Water is able to pass through a semipermeable membrane, but solutes (dissolved molecules like salts, sugars, and other compounds) cannot. When the concentration of solutes is greater on one side of the membrane, water diffuses across the membrane from the side with the lower concentration (more water) to the side with the higher concentration (less water) until the concentrations on both sides become equal. This diffusion of water is called osmosis , and it can cause extreme osmotic pressure on a cell when its external environment changes. The external environment of a cell can be described as an isotonic, hypertonic, or hypotonic medium. In an isotonic medium , the solute concentrations inside and outside the cell are approximately equal, so there is no net movement of water across the cell membrane. In a hypertonic medium , the solute concentration outside the cell exceeds that inside the cell, so water diffuses out of the cell and into the external medium. In a hypotonic medium , the solute concentration inside the cell exceeds that outside of the cell, so water will move by osmosis into the cell. This causes the cell to swell and potentially lyse, or burst. The degree to which a particular cell is able to withstand changes in osmotic pressure is called tonicity. Cells that have a cell wall are better able to withstand subtle changes in osmotic pressure and maintain their shape. In hypertonic environments, cells that lack a cell wall can become dehydrated, causing crenation , or shriveling of the cell; the plasma membrane contracts and appears scalloped or notched ( Figure 3.15 ). By contrast, cells that possess a cell wall undergo plasmolysis rather than crenation. In plasmolysis, the plasma membrane contracts and detaches from the cell wall, and there is a decrease in interior volume, but the cell wall remains intact, thus allowing the cell to maintain some shape and integrity for a period of time ( Figure 3.16 ). Likewise, cells that lack a cell wall are more prone to lysis in hypotonic environments. The presence of a cell wall allows the cell to maintain its shape and integrity for a longer time before lysing ( Figure 3.16 ). Check Your Understanding Explain the difference between cell morphology and arrangement. What advantages do cell walls provide prokaryotic cells? The Nucleoid All cellular life has a DNA genome organized into one or more chromosomes. Prokaryotic chromosomes are typically circular, haploid (unpaired), and not bound by a complex nuclear membrane. Prokaryotic DNA and DNA-associated proteins are concentrated within the nucleoid region of the cell ( Figure 3.17 ). In general, prokaryotic DNA interacts with nucleoid-associated proteins (NAPs) that assist in the organization and packaging of the chromosome. In bacteria, NAPs function similar to histones, which are the DNA-organizing proteins found in eukaryotic cells. In archaea, the nucleoid is organized by either NAPs or histone-like DNA organizing proteins. Plasmids Prokaryotic cells may also contain extrachromosomal DNA, or DNA that is not part of the chromosome. This extrachromosomal DNA is found in plasmid s , which are small, circular, double-stranded DNA molecules. Cells that have plasmids often have hundreds of them within a single cell. Plasmids are more commonly found in bacteria; however, plasmids have been found in archaea and eukaryotic organisms. Plasmids often carry genes that confer advantageous traits such as antibiotic resistance; thus, they are important to the survival of the organism. We will discuss plasmids in more detail in Mechanisms of Microbial Genetics . Ribosomes All cellular life synthesizes proteins, and organisms in all three domains of life possess ribosomes, structures responsible for protein synthesis. However, ribosomes in each of the three domains are structurally different. Ribosomes, themselves, are constructed from proteins, along with ribosomal RNA (rRNA). Prokaryotic ribosomes are found in the cytoplasm. They are called 70S ribosome s because they have a size of 70S ( Figure 3.18 ), whereas eukaryotic cytoplasmic ribosomes have a size of 80S. (The S stands for Svedberg unit, a measure of sedimentation in an ultracentrifuge, which is based on size, shape, and surface qualities of the structure being analyzed). Although they are the same size, bacterial and archaeal ribosomes have different proteins and rRNA molecules, and the archaeal versions are more similar to their eukaryotic counterparts than to those found in bacteria. Inclusions As single-celled organisms living in unstable environments, some prokaryotic cells have the ability to store excess nutrients within cytoplasmic structures called inclusions . Storing nutrients in a polymerized form is advantageous because it reduces the buildup of osmotic pressure that occurs as a cell accumulates solutes. Various types of inclusions store glycogen and starches, which contain carbon that cells can access for energy. Volutin granules, also called metachromatic granules because of their staining characteristics, are inclusions that store polymerized inorganic phosphate that can be used in metabolism and assist in the formation of biofilms. Microbes known to contain volutin granules include the archaea Methanosarcina , the bacterium Corynebacterium diphtheriae , and the unicellular eukaryotic alga Chlamydomonas . Sulfur granules, another type of inclusion, are found in sulfur bacteria of the genus Thiobacillus ; these granules store elemental sulfur, which the bacteria use for metabolism. Occasionally, certain types of inclusions are surrounded by a phospholipid monolayer embedded with protein. Polyhydroxybutyrate (PHB) , which can be produced by species of Bacillus and Pseudomonas , is an example of an inclusion that displays this type of monolayer structure. Industrially, PHB has also been used as a source of biodegradable polymers for bioplastics. Several different types of inclusions are shown in Figure 3.19 . Some prokaryotic cells have other types of inclusions that serve purposes other than nutrient storage. For example, some prokaryotic cells produce gas vacuoles, accumulations of small, protein-lined vesicles of gas. These gas vacuoles allow the prokaryotic cells that synthesize them to alter their buoyancy so that they can adjust their location in the water column. Magnetotactic bacteria, such as Magnetospirillum magnetotacticum , contain magnetosomes , which are inclusions of magnetic iron oxide or iron sulfide surrounded by a lipid layer. These allow cells to align along a magnetic field, aiding their movement ( Figure 3.19 ). Cyanobacteria such as Anabaena cylindrica and bacteria such as Halothiobacillus neapolitanus produce carboxysome inclusions. Carboxysomes are composed of outer shells of thousands of protein subunits. Their interior is filled with ribulose-1,5-bisphosphate carboxylase/oxygenase (RuBisCO) and carbonic anhydrase. Both of these compounds are used for carbon metabolism. Some prokaryotic cells also possess carboxysomes that sequester functionally related enzymes in one location. These structures are considered proto-organelles because they compartmentalize important compounds or chemical reactions, much like many eukaryotic organelles. Endospores Bacterial cells are generally observed as vegetative cells , but some genera of bacteria have the ability to form endospores , structures that essentially protect the bacterial genome in a dormant state when environmental conditions are unfavorable. Endospores (not to be confused with the reproductive spores formed by fungi) allow some bacterial cells to survive long periods without food or water, as well as exposure to chemicals, extreme temperatures, and even radiation. Table 3.1 compares the characteristics of vegetative cells and endospores. Characteristics of Vegetative Cells versus Endospores Vegetative Cells Endospores Sensitive to extreme temperatures and radiation Resistant to extreme temperatures and radiation Gram-positive Do not absorb Gram stain, only special endospore stains (see Staining Microscopic Specimens ) Normal water content and enzymatic activity Dehydrated; no metabolic activity Capable of active growth and metabolism Dormant; no growth or metabolic activity Table 3.1 The process by which vegetative cells transform into endospores is called sporulation , and it generally begins when nutrients become depleted or environmental conditions become otherwise unfavorable ( Figure 3.20 ). The process begins with the formation of a septum in the vegetative bacterial cell. The septum divides the cell asymmetrically, separating a DNA forespore from the mother cell. The forespore, which will form the core of the endospore, is essentially a copy of the cell’s chromosomes, and is separated from the mother cell by a second membrane. A cortex gradually forms around the forespore by laying down layers of calcium and dipicolinic acid between membranes. A protein spore coat then forms around the cortex while the DNA of the mother cell disintegrates. Further maturation of the endospore occurs with the formation of an outermost exosporium. The endospore is released upon disintegration of the mother cell, completing sporulation. Endospores of certain species have been shown to persist in a dormant state for extended periods of time, up to thousands of years. 17 However, when living conditions improve, endospores undergo germination , reentering a vegetative state. After germination, the cell becomes metabolically active again and is able to carry out all of its normal functions, including growth and cell division. 17 F. Rothfuss, M Bender, R Conrad. “Survival and Activity of Bacteria in a Deep, Aged Lake Sediment (Lake Constance).” Microbial Ecology 33 no. 1 (1997):69–77. Not all bacteria have the ability to form endospores; however, there are a number of clinically significant endospore-forming gram-positive bacteria of the genera Bacillus and Clostridium . These include B. anthracis , the causative agent of anthrax , which produces endospores capable of survive for many decades 18 ; C. tetani (causes tetanus ); C. difficile (causes pseudomembranous colitis ); C. perfringens (causes gas gangrene ); and C. botulinum (causes botulism ). Pathogens such as these are particularly difficult to combat because their endospores are so hard to kill. Special sterilization methods for endospore-forming bacteria are discussed in Control of Microbial Growth . 18 R. Sinclair et al. “Persistence of Category A Select Agents in the Environment.” Applied and Environmental Microbiology 74 no. 3 (2008):555–563. Check Your Understanding What is an inclusion? What is the function of an endospore? Plasma Membrane Structures that enclose the cytoplasm and internal structures of the cell are known collectively as the cell envelope . In prokaryotic cells, the structures of the cell envelope vary depending on the type of cell and organism. Most (but not all) prokaryotic cells have a cell wall , but the makeup of this cell wall varies. All cells (prokaryotic and eukaryotic) have a plasma membrane (also called cytoplasmic membrane or cell membrane ) that exhibits selective permeability, allowing some molecules to enter or leave the cell while restricting the passage of others. The structure of the plasma membrane is often described in terms of the fluid mosaic model , which refers to the ability of membrane components to move fluidly within the plane of the membrane, as well as the mosaic-like composition of the components, which include a diverse array of lipid and protein components ( Figure 3.21 ). The plasma membrane structure of most bacterial and eukaryotic cell types is a bilayer composed mainly of phospholipids formed with ester linkages and proteins. These phospholipids and proteins have the ability to move laterally within the plane of the membranes as well as between the two phospholipid layers. Archaeal membranes are fundamentally different from bacterial and eukaryotic membranes in a few significant ways. First, archaeal membrane phospholipids are formed with ether linkages, in contrast to the ester linkages found in bacterial or eukaryotic cell membranes. Second, archaeal phospholipids have branched chains, whereas those of bacterial and eukaryotic cells are straight chained. Finally, although some archaeal membranes can be formed of bilayers like those found in bacteria and eukaryotes, other archaeal plasma membranes are lipid monolayers. Proteins on the cell’s surface are important for a variety of functions, including cell-to-cell communication, and sensing environmental conditions and pathogenic virulence factors. Membrane proteins and phospholipids may have carbohydrates (sugars) associated with them and are called glycoproteins or glycolipids, respectively. These glycoprotein and glycolipid complexes extend out from the surface of the cell, allowing the cell to interact with the external environment ( Figure 3.21 ). Glycoproteins and glycolipids in the plasma membrane can vary considerably in chemical composition among archaea, bacteria, and eukaryotes, allowing scientists to use them to characterize unique species. Plasma membranes from different cells types also contain unique phospholipids, which contain fatty acids. As described in Using Biochemistry to Identify Microorganisms , phospholipid-derived fatty acid analysis (PLFA) profiles can be used to identify unique types of cells based on differences in fatty acids. Archaea, bacteria, and eukaryotes each have a unique PFLA profile. Membrane Transport Mechanisms One of the most important functions of the plasma membrane is to control the transport of molecules into and out of the cell. Internal conditions must be maintained within a certain range despite any changes in the external environment. The transport of substances across the plasma membrane allows cells to do so. Cells use various modes of transport across the plasma membrane. For example, molecules moving from a higher concentration to a lower concentration with the concentration gradient are transported by simple diffusion , also known as passive transport ( Figure 3.22 ). Some small molecules, like carbon dioxide, may cross the membrane bilayer directly by simple diffusion. However, charged molecules, as well as large molecules, need the help of carriers or channels in the membrane. These structures ferry molecules across the membrane, a process known as facilitated diffusion ( Figure 3.23 ). Active transport occurs when cells move molecules across their membrane against concentration gradients ( Figure 3.24 ). A major difference between passive and active transport is that active transport requires adenosine triphosphate (ATP) or other forms of energy to move molecules “uphill.” Therefore, active transport structures are often called “pumps.” Group translocation also transports substances into bacterial cells. In this case, as a molecule moves into a cell against its concentration gradient, it is chemically modified so that it does not require transport against an unfavorable concentration gradient. A common example of this is the bacterial phosphotransferase system, a series of carriers that phosphorylates (i.e., adds phosphate ions to) glucose or other sugars upon entry into cells. Since the phosphorylation of sugars is required during the early stages of sugar metabolism, the phosphotransferase system is considered to be an energy neutral system. Photosynthetic Membrane Structures Some prokaryotic cells, namely cyanobacteria and photosynthetic bacteria , have membrane structures that enable them to perform photosynthesis. These structures consist of an infolding of the plasma membrane that encloses photosynthetic pigments such as green chlorophylls and bacteriochlorophylls . In cyanobacteria, these membrane structures are called thylakoids; in photosynthetic bacteria, they are called chromatophores, lamellae, or chlorosomes. Cell Wall The primary function of the cell wall is to protect the cell from harsh conditions in the outside environment. When present, there are notable similarities and differences among the cell walls of archaea, bacteria, and eukaryotes. The major component of bacterial cell walls is called peptidoglycan (or murein ); it is only found in bacteria. Structurally, peptidoglycan resembles a layer of meshwork or fabric ( Figure 3.25 ). Each layer is composed of long chains of alternating molecules of N-acetylglucosamine (NAG) and N-acetylmuramic acid (NAM). The structure of the long chains has significant two-dimensional tensile strength due to the formation of peptide bridges that connect NAG and NAM within each peptidoglycan layer. In gram-negative bacteria, tetrapeptide chains extending from each NAM unit are directly cross-linked, whereas in gram-positive bacteria, these tetrapeptide chains are linked by pentaglycine cross-bridges. Peptidoglycan subunits are made inside of the bacterial cell and then exported and assembled in layers, giving the cell its shape. Since peptidoglycan is unique to bacteria, many antibiotic drugs are designed to interfere with peptidoglycan synthesis, weakening the cell wall and making bacterial cells more susceptible to the effects of osmotic pressure (see Mechanisms of Antibacterial Drugs ). In addition, certain cells of the human immune system are able “recognize” bacterial pathogens by detecting peptidoglycan on the surface of a bacterial cell; these cells then engulf and destroy the bacterial cell, using enzymes such as lysozyme, which breaks down and digests the peptidoglycan in their cell walls (see Pathogen Recognition and Phagocytosis ). The Gram staining protocol (see Staining Microscopic Specimens ) is used to differentiate two common types of cell wall structures ( Figure 3.26 ). Gram-positive cells have a cell wall consisting of many layers of peptidoglycan totaling 30–100 nm in thickness. These peptidoglycan layers are commonly embedded with teichoic acids (TAs), carbohydrate chains that extend through and beyond the peptidoglycan layer. 19 TA is thought to stabilize peptidoglycan by increasing its rigidity. TA also plays a role in the ability of pathogenic gram-positive bacteria such as Streptococcus to bind to certain proteins on the surface of host cells, enhancing their ability to cause infection. In addition to peptidoglycan and TAs, bacteria of the family Mycobacteriaceae have an external layer of waxy mycolic acids in their cell wall; as described in Staining Microscopic Specimens , these bacteria are referred to as acid-fast, since acid-fast stains must be used to penetrate the mycolic acid layer for purposes of microscopy ( Figure 3.27 ). 19 T.J. Silhavy, D. Kahne, S. Walker. “The Bacterial Cell Envelope.” Cold Spring Harbor Perspectives in Biology 2 no. 5 (2010):a000414. Gram-negative cells have a much thinner layer of peptidoglycan (no more than about 4 nm thick 21 ) than gram-positive cells , and the overall structure of their cell envelope is more complex. In gram-negative cells , a gel-like matrix occupies the periplasmic space between the cell wall and the plasma membrane, and there is a second lipid bilayer called the outer membrane , which is external to the peptidoglycan layer ( Figure 3.26 ). This outer membrane is attached to the peptidoglycan by murein lipoprotein. The outer leaflet of the outer membrane contains the molecule lipopolysaccharide (LPS) , which functions as an endotoxin in infections involving gram-negative bacteria, contributing to symptoms such as fever, hemorrhaging, and septic shock. Each LPS molecule is composed of Lipid A, a core polysaccharide, and an O side chain that is composed of sugar-like molecules that comprise the external face of the LPS ( Figure 3.28 ). The composition of the O side chain varies between different species and strains of bacteria. Parts of the O side chain called antigens can be detected using serological or immunological tests to identify specific pathogenic strains like Escherichia coli O157:H7 , a deadly strain of bacteria that causes bloody diarrhea and kidney failure. 21 L. Gana, S. Chena, G.J. Jensena. “Molecular Organization of Gram-Negative Peptidoglycan.” Proceedings of the National Academy of Sciences of the United States of America 105 no. 48 (2008):18953–18957. Archaeal cell wall structure differs from that of bacteria in several significant ways. First, archaeal cell walls do not contain peptidoglycan; instead, they contain a similar polymer called pseudopeptidoglycan (pseudomurein) in which NAM is replaced with a different subunit. Other archaea may have a layer of glycoproteins or polysaccharides that serves as the cell wall instead of pseudopeptidoglycan. Last, as is the case with some bacterial species, there are a few archaea that appear to lack cell walls entirely. Glycocalyces and S-Layers Although most prokaryotic cells have cell walls, some may have additional cell envelope structures exterior to the cell wall, such as glycocalyces and S-layers. A glycocalyx is a sugar coat, of which there are two important types: capsules and slime layers. A capsule is an organized layer located outside of the cell wall and usually composed of polysaccharides or proteins ( Figure 3.29 ). A slime layer is a less tightly organized layer that is only loosely attached to the cell wall and can be more easily washed off. Slime layers may be composed of polysaccharides, glycoproteins, or glycolipids. Glycocalyces allows cells to adhere to surfaces, aiding in the formation of biofilms (colonies of microbes that form in layers on surfaces). In nature, most microbes live in mixed communities within biofilms , partly because the biofilm affords them some level of protection. Biofilms generally hold water like a sponge, preventing desiccation. They also protect cells from predation and hinder the action of antibiotics and disinfectants. All of these properties are advantageous to the microbes living in a biofilm, but they present challenges in a clinical setting, where the goal is often to eliminate microbes. The ability to produce a capsule can contribute to a microbe’s pathogenicity (ability to cause disease) because the capsule can make it more difficult for phagocytic cells (such as white blood cells) to engulf and kill the microorganism. Streptococcus pneumoniae , for example, produces a capsule that is well known to aid in this bacterium’s pathogenicity. As explained in Staining Microscopic specimens , capsules are difficult to stain for microscopy; negative staining techniques are typically used. An S-layer is another type of cell envelope structure; it is composed of a mixture of structural proteins and glycoproteins. In bacteria, S-layers are found outside the cell wall, but in some archaea, the S-layer serves as the cell wall. The exact function of S-layers is not entirely understood, and they are difficult to study; but available evidence suggests that they may play a variety of functions in different prokaryotic cells, such as helping the cell withstand osmotic pressure and, for certain pathogens, interacting with the host immune system. Clinical Focus Part 3 After diagnosing Barbara with pneumonia, the PA writes her a prescription for amoxicillin, a commonly-prescribed type of penicillin derivative. More than a week later, despite taking the full course as directed, Barbara still feels weak and is not fully recovered, although she is still able to get through her daily activities. She returns to the health center for a follow-up visit. Many types of bacteria, fungi, and viruses can cause pneumonia. Amoxicillin targets the peptidoglycan of bacterial cell walls. Since the amoxicillin has not resolved Barbara’s symptoms, the PA concludes that the causative agent probably lacks peptidoglycan, meaning that the pathogen could be a virus, a fungus, or a bacterium that lacks peptidoglycan. Another possibility is that the pathogen is a bacterium containing peptidoglycan but has developed resistance to amoxicillin. How can the PA definitively identify the cause of Barbara’s pneumonia? What form of treatment should the PA prescribe, given that the amoxicillin was ineffective? Jump to the next Clinical Focus box. Go back to the previous Clinical Focus box. Filamentous Appendages Many bacterial cells have protein appendages embedded within their cell envelopes that extend outward, allowing interaction with the environment. These appendages can attach to other surfaces, transfer DNA, or provide movement. Filamentous appendages include fimbriae, pili, and flagella. Fimbriae and Pili Fimbriae and pili are structurally similar and, because differentiation between the two is problematic, these terms are often used interchangeably. 22 23 The term fimbriae commonly refers to short bristle-like proteins projecting from the cell surface by the hundreds. Fimbriae enable a cell to attach to surfaces and to other cells. For pathogenic bacteria, adherence to host cells is important for colonization, infectivity, and virulence. Adherence to surfaces is also important in biofilm formation. 22 J.A. Garnetta et al. “Structural Insights Into the Biogenesis and Biofilm Formation by the Escherichia coli Common Pilus.” Proceedings of the National Academy of Sciences of the United States of America 109 no. 10 (2012):3950–3955. 23 T. Proft, E.N. Baker. “Pili in Gram-Negative and Gram-Positive Bacteria—Structure, Assembly and Their Role in Disease.” Cellular and Molecular Life Sciences 66 (2009):613. The term pili (singular: pilus) commonly refers to longer, less numerous protein appendages that aid in attachment to surfaces ( Figure 3.30 ). A specific type of pilus, called the F pilus or sex pilus , is important in the transfer of DNA between bacterial cells, which occurs between members of the same generation when two cells physically transfer or exchange parts of their respective genomes (see How Asexual Prokaryotes Achieve Genetic Diversity ). Micro Connections Group A Strep Before the structure and function of the various components of the bacterial cell envelope were well understood, scientists were already using cell envelope characteristics to classify bacteria. In 1933, Rebecca Lancefield proposed a method for serotyping various β-hemolytic strains of Streptococcus species using an agglutination assay, a technique using the clumping of bacteria to detect specific cell-surface antigens. In doing so, Lancefield discovered that one group of S. pyogenes , found in Group A, was associated with a variety of human diseases. She determined that various strains of Group A strep could be distinguished from each other based on variations in specific cell surface proteins that she named M proteins. Today, more than 80 different strains of Group A strep have been identified based on M proteins. Various strains of Group A strep are associated with a wide variety of human infections, including streptococcal pharyngitis ( strep throat ), impetigo , toxic shock syndrome , scarlet fever , rheumatic fever , and necrotizing fasciitis . The M protein is an important virulence factor for Group A strep, helping these strains evade the immune system. Changes in M proteins appear to alter the infectivity of a particular strain of Group A strep. Flagella Flagella are structures used by cells to move in aqueous environments. Bacterial flagella act like propellers. They are stiff spiral filaments composed of flagellin protein subunits that extend outward from the cell and spin in solution. The basal body is the motor for the flagellum and is embedded in the plasma membrane ( Figure 3.31 ). A hook region connects the basal body to the filament. Gram-positive and gram-negative bacteria have different basal body configurations due to differences in cell wall structure. Different types of motile bacteria exhibit different arrangements of flagella ( Figure 3.32 ). A bacterium with a singular flagellum, typically located at one end of the cell (polar), is said to have a monotrichous flagellum. An example of a monotrichously flagellated bacterial pathogen is Vibrio cholerae , the gram-negative bacterium that causes cholera. Cells with amphitrichous flagella have a flagellum or tufts of flagella at each end. An example is Spirillum minor , the cause of spirillary (Asian) rat-bite fever or sodoku. Cells with lophotrichous flagella have a tuft at one end of the cell. The gram-negative bacillus Pseudomonas aeruginosa , an opportunistic pathogen known for causing many infections, including “swimmer’s ear” and burn wound infections, has lophotrichous flagella. Flagella that cover the entire surface of a bacterial cell are called peritrichous flagella. The gram-negative bacterium E. coli shows a peritrichous arrangement of flagella. Directional movement depends on the configuration of the flagella. Bacteria can move in response to a variety of environmental signals, including light ( phototaxis ), magnetic fields ( magnetotaxis ) using magnetosomes, and, most commonly, chemical gradients ( chemotaxis ). Purposeful movement toward a chemical attractant, like a food source, or away from a repellent, like a poisonous chemical, is achieved by increasing the length of runs and decreasing the length of tumbles . When running, flagella rotate in a counterclockwise direction, allowing the bacterial cell to move forward. In a peritrichous bacterium, the flagella are all bundled together in a very streamlined way ( Figure 3.33 ), allowing for efficient movement. When tumbling, flagella are splayed out while rotating in a clockwise direction, creating a looping motion and preventing meaningful forward movement but reorienting the cell toward the direction of the attractant. When an attractant exists, runs and tumbles still occur; however, the length of runs is longer, while the length of the tumbles is reduced, allowing overall movement toward the higher concentration of the attractant. When no chemical gradient exists, the lengths of runs and tumbles are more equal, and overall movement is more random ( Figure 3.34 ). Check Your Understanding What is the peptidoglycan layer and how does it differ between gram-positive and gram-negative bacteria? Compare and contrast monotrichous, amphitrichous, lophotrichous, and peritrichous flagella. 3.4 Unique Characteristics of Eukaryotic Cells Learning Objectives Explain the distinguishing characteristics of eukaryotic cells Describe internal and external structures of eukaryotic cells in terms of their physical structure, chemical structure, and function Identify and describe structures and organelles unique to eukaryotic cells Compare and contrast similar structures found in prokaryotic and eukaryotic cells Eukaryotic organisms include protozoans, algae, fungi, plants, and animals. Some eukaryotic cells are independent, single-celled microorganisms, whereas others are part of multicellular organisms. The cells of eukaryotic organisms have several distinguishing characteristics. Above all, eukaryotic cells are defined by the presence of a nucleus surrounded by a complex nuclear membrane. Also, eukaryotic cells are characterized by the presence of membrane-bound organelles in the cytoplasm. Organelles such as mitochondria, the endoplasmic reticulum (ER), Golgi apparatus, lysosomes, and peroxisomes are held in place by the cytoskeleton , an internal network that supports transport of intracellular components and helps maintain cell shape ( Figure 3.35 ). The genome of eukaryotic cells is packaged in multiple, rod-shaped chromosomes as opposed to the single, circular-shaped chromosome that characterizes most prokaryotic cells. Table 3.2 compares the characteristics of eukaryotic cell structures with those of bacteria and archaea. Summary of Cell Structures Cell Structure Prokaryotes Eukaryotes Bacteria Archaea Size ~0.5–1 μm ~0.5–1 μm ~5–20 μm Surface area-to-volume ratio High High Low Nucleus No No Yes Genome characteristics Single chromosome Circular Haploid Lacks histones Single chromosome Circular Haploid Contains histones Multiple chromosomes Linear Haploid or diploid Contains histones Cell division Binary fission Binary fission Mitosis, meiosis Membrane lipid composition Ester-linked Straight-chain fatty acids Bilayer Ether-linked Branched isoprenoids Bilayer or monolayer Ester-linked Straight-chain fatty acids Sterols Bilayer Cell wall composition Peptidoglycan, or None Pseudopeptidoglycan, or Glycopeptide, or Polysaccharide, or Protein (S-layer), or None Cellulose (plants, some algae) Chitin (molluscs, insects, crustaceans, and fungi) Silica (some algae) Most others lack cell walls Motility structures Rigid spiral flagella composed of flagellin Rigid spiral flagella composed of archaeal flagellins Flexible flagella and cilia composed of microtubules Membrane-bound organelles No No Yes Endomembrane system No No Yes (ER, Golgi, lysosomes) Ribosomes 70S 70S 80S in cytoplasm and rough ER 70S in mitochondria, chloroplasts Table 3.2 Cell Morphologies Eukaryotic cells display a wide variety of different cell morphologies . Possible shapes include spheroid, ovoid, cuboidal, cylindrical, flat, lenticular, fusiform, discoidal, crescent, ring stellate, and polygonal ( Figure 3.36 ). Some eukaryotic cells are irregular in shape, and some are capable of changing shape. The shape of a particular type of eukaryotic cell may be influenced by factors such as its primary function, the organization of its cytoskeleton, the viscosity of its cytoplasm, the rigidity of its cell membrane or cell wall (if it has one), and the physical pressure exerted on it by the surrounding environment and/or adjoining cells. Check Your Understanding Identify two differences between eukaryotic and prokaryotic cells. Nucleus Unlike prokaryotic cells, in which DNA is loosely contained in the nucleoid region, eukaryotic cells possess a nucleus , which is surrounded by a complex nuclear membrane that houses the DNA genome ( Figure 3.37 ). By containing the cell’s DNA, the nucleus ultimately controls all activities of the cell and also serves an essential role in reproduction and heredity. Eukaryotic cells typically have their DNA organized into multiple linear chromosomes. The DNA within the nucleus is highly organized and condensed to fit inside the nucleus, which is accomplished by wrapping the DNA around proteins called histones. Although most eukaryotic cells have only one nucleus, exceptions exist. For example, protozoans of the genus Paramecium typically have two complete nuclei: a small nucleus that is used for reproduction (micronucleus) and a large nucleus that directs cellular metabolism (macronucleus). Additionally, some fungi transiently form cells with two nuclei, called heterokaryotic cells, during sexual reproduction. Cells whose nuclei divide, but whose cytoplasm does not, are called coenocytes . The nucleus is bound by a complex nuclear membrane , often called the nuclear envelope , that consists of two distinct lipid bilayers that are contiguous with each other ( Figure 3.38 ). Despite these connections between the inner and outer membranes, each membrane contains unique lipids and proteins on its inner and outer surfaces. The nuclear envelope contains nuclear pores, which are large, rosette-shaped protein complexes that control the movement of materials into and out of the nucleus. The overall shape of the nucleus is determined by the nuclear lamina , a meshwork of intermediate filaments found just inside the nuclear envelope membranes. Outside the nucleus, additional intermediate filaments form a looser mesh and serve to anchor the nucleus in position within the cell. Nucleolus The nucleolus is a dense region within the nucleus where ribosomal RNA (rRNA) biosynthesis occurs. In addition, the nucleolus is also the site where assembly of ribosomes begins. Preribosomal complexes are assembled from rRNA and proteins in the nucleolus; they are then transported out to the cytoplasm, where ribosome assembly is completed ( Figure 3.39 ). Ribosomes Ribosomes found in eukaryotic organelles such as mitochondria or chloroplasts have 70S ribosomes—the same size as prokaryotic ribosomes. However, nonorganelle-associated ribosomes in eukaryotic cells are 80S ribosomes , composed of a 40S small subunit and a 60S large subunit. In terms of size and composition, this makes them distinct from the ribosomes of prokaryotic cells. The two types of nonorganelle-associated eukaryotic ribosomes are defined by their location in the cell: free ribosomes and membrane-bound ribosomes . Free ribosomes are found in the cytoplasm and serve to synthesize water-soluble proteins; membrane-bound ribosomes are found attached to the rough endoplasmic reticulum and make proteins for insertion into the cell membrane or proteins destined for export from the cell. The differences between eukaryotic and prokaryotic ribosomes are clinically relevant because certain antibiotic drugs are designed to target one or the other. For example, cycloheximide targets eukaryotic action, whereas chloramphenicol targets prokaryotic ribosomes. 24 Since human cells are eukaryotic, they generally are not harmed by antibiotics that destroy the prokaryotic ribosomes in bacteria. However, sometimes negative side effects may occur because mitochondria in human cells contain prokaryotic ribosomes. 24 A.E. Barnhill, M.T. Brewer, S.A. Carlson. “Adverse Effects of Antimicrobials via Predictable or Idiosyncratic Inhibition of Host Mitochondrial Components.” Antimicrobial Agents and Chemotherapy 56 no. 8 (2012):4046–4051. Endomembrane System The endomembrane system , unique to eukaryotic cells, is a series of membranous tubules, sacs, and flattened disks that synthesize many cell components and move materials around within the cell ( Figure 3.40 ). Because of their larger cell size, eukaryotic cells require this system to transport materials that cannot be dispersed by diffusion alone. The endomembrane system comprises several organelles and connections between them, including the endoplasmic reticulum, Golgi apparatus, lysosomes, and vesicles. Endoplasmic Reticulum The endoplasmic reticulum (ER) is an interconnected array of tubules and cisternae (flattened sacs) with a single lipid bilayer ( Figure 3.41 ). The spaces inside of the cisternae are called lumen of the ER. There are two types of ER, rough endoplasmic reticulum (RER) and smooth endoplasmic reticulum (SER) . These two different types of ER are sites for the synthesis of distinctly different types of molecules. RER is studded with ribosomes bound on the cytoplasmic side of the membrane. These ribosomes make proteins destined for the plasma membrane ( Figure 3.41 ). Following synthesis, these proteins are inserted into the membrane of the RER. Small sacs of the RER containing these newly synthesized proteins then bud off as transport vesicles and move either to the Golgi apparatus for further processing, directly to the plasma membrane, to the membrane of another organelle, or out of the cell. Transport vesicles are single-lipid, bilayer, membranous spheres with hollow interiors that carry molecules. SER does not have ribosomes and, therefore, appears “smooth.” It is involved in biosynthesis of lipids, carbohydrate metabolism, and detoxification of toxic compounds within the cell. Golgi Apparatus The Golgi apparatus was discovered within the endomembrane system in 1898 by Italian scientist Camillo Golgi (1843–1926), who developed a novel staining technique that showed stacked membrane structures within the cells of Plasmodium , the causative agent of malaria. The Golgi apparatus is composed of a series of membranous disks called dictyosomes, each having a single lipid bilayer, that are stacked together ( Figure 3.42 ). Enzymes in the Golgi apparatus modify lipids and proteins transported from the ER to the Golgi, often adding carbohydrate components to them, producing glycolipids, glycoproteins, or proteoglycans. Glycolipids and glycoproteins are often inserted into the plasma membrane and are important for signal recognition by other cells or infectious particles. Different types of cells can be distinguished from one another by the structure and arrangement of the glycolipids and glycoproteins contained in their plasma membranes. These glycolipids and glycoproteins commonly also serve as cell surface receptors. Transport vesicles leaving the ER fuse with a Golgi apparatus on its receiving, or cis , face. The proteins are processed within the Golgi apparatus, and then additional transport vesicles containing the modified proteins and lipids pinch off from the Golgi apparatus on its outgoing, or trans , face. These outgoing vesicles move to and fuse with the plasma membrane or the membrane of other organelles. Exocytosis is the process by which secretory vesicles (spherical membranous sacs) release their contents to the cell’s exterior ( Figure 3.42 ). All cells have constitutive secretory pathways in which secretory vesicles transport soluble proteins that are released from the cell continually (constitutively). Certain specialized cells also have regulated secretory pathways , which are used to store soluble proteins in secretory vesicles. Regulated secretion involves substances that are only released in response to certain events or signals. For example, certain cells of the human immune system (e.g., mast cells) secrete histamine in response to the presence of foreign objects or pathogens in the body. Histamine is a compound that triggers various mechanisms used by the immune system to eliminate pathogens. Lysosomes In the 1960s, Belgian scientist Christian de Duve (1917–2013) discovered lysosomes , membrane-bound organelles of the endomembrane system that contain digestive enzymes. Certain types of eukaryotic cells use lysosomes to break down various particles, such as food, damaged organelles or cellular debris, microorganisms, or immune complexes. Compartmentalization of the digestive enzymes within the lysosome allows the cell to efficiently digest matter without harming the cytoplasmic components of the cell. Check Your Understanding Name the components of the endomembrane system and describe the function of each component. Peroxisomes Christian de Duve is also credited with the discovery of peroxisomes , membrane-bound organelles that are not part of the endomembrane system ( Figure 3.43 ). Peroxisomes form independently in the cytoplasm from the synthesis of peroxin proteins by free ribosomes and the incorporation of these peroxin proteins into existing peroxisomes. Growing peroxisomes then divide by a process similar to binary fission. Peroxisomes were first named for their ability to produce hydrogen peroxide, a highly reactive molecule that helps to break down molecules such as uric acid, amino acids, and fatty acids. Peroxisomes also possess the enzyme catalase, which can degrade hydrogen peroxide. Along with the SER, peroxisomes also play a role in lipid biosynthesis. Like lysosomes, the compartmentalization of these degradative molecules within an organelle helps protect the cytoplasmic contents from unwanted damage. The peroxisomes of certain organisms are specialized to meet their particular functional needs. For example, glyoxysomes are modified peroxisomes of yeasts and plant cells that perform several metabolic functions, including the production of sugar molecules. Similarly, glycosomes are modified peroxisomes made by certain trypanosomes, the pathogenic protozoans that cause Chagas disease and African sleeping sickness . Cytoskeleton Eukaryotic cells have an internal cytoskeleton made of microfilaments , intermediate filaments , and microtubules . This matrix of fibers and tubes provides structural support as well as a network over which materials can be transported within the cell and on which organelles can be anchored ( Figure 3.44 ). For example, the process of exocytosis involves the movement of a vesicle via the cytoskeletal network to the plasma membrane, where it can release its contents. Microfilaments are composed of two intertwined strands of actin, each composed of actin monomers forming filamentous cables 6 nm in diameter 25 ( Figure 3.45 ). The actin filaments work together with motor proteins, like myosin, to effect muscle contraction in animals or the amoeboid movement of some eukaryotic microbes. In ameboid organisms, actin can be found in two forms: a stiffer, polymerized, gel form and a more fluid, unpolymerized soluble form. Actin in the gel form creates stability in the ectoplasm, the gel-like area of cytoplasm just inside the plasma membrane of ameboid protozoans. 25 Fuchs E, Cleveland DW. “A Structural Scaffolding of Intermediate Filaments in Health and Disease.” Science 279 no. 5350 (1998):514–519. Temporary extensions of the cytoplasmic membrane called pseudopodia (meaning “false feet”) are produced through the forward flow of soluble actin filaments into the pseudopodia, followed by the gel-sol cycling of the actin filaments, resulting in cell motility. Once the cytoplasm extends outward, forming a pseudopodium, the remaining cytoplasm flows up to join the leading edge, thereby creating forward locomotion. Beyond amoeboid movement, microfilaments are also involved in a variety of other processes in eukaryotic cells, including cytoplasmic streaming (the movement or circulation of cytoplasm within the cell), cleavage furrow formation during cell division, and muscle movement in animals ( Figure 3.45 ). These functions are the result of the dynamic nature of microfilaments, which can polymerize and depolymerize relatively easily in response to cellular signals, and their interactions with molecular motors in different types of eukaryotic cells. Intermediate filaments ( Figure 3.46 ) are a diverse group of cytoskeletal filaments that act as cables within the cell. They are termed “intermediate” because their 10-nm diameter is thicker than that of actin but thinner than that of microtubules. 26 They are composed of several strands of polymerized subunits that, in turn, are made up of a wide variety of monomers. Intermediate filaments tend to be more permanent in the cell and maintain the position of the nucleus. They also form the nuclear lamina (lining or layer) just inside the nuclear envelope. Additionally, intermediate filaments play a role in anchoring cells together in animal tissues. The intermediate filament protein desmin is found in desmosomes, the protein structures that join muscle cells together and help them resist external physical forces. The intermediate filament protein keratin is a structural protein found in hair, skin, and nails. 26 E. Fuchs, D.W. Cleveland. “A Structural Scaffolding of Intermediate Filaments in Health and Disease.” Science 279 no. 5350 (1998):514–519. Microtubules ( Figure 3.47 ) are a third type of cytoskeletal fiber composed of tubulin dimers (α tubulin and β tubulin). These form hollow tubes 23 nm in diameter that are used as girders within the cytoskeleton. 27 Like microfilaments, microtubules are dynamic and have the ability to rapidly assemble and disassemble. Microtubules also work with motor proteins (such as dynein and kinesin) to move organelles and vesicles around within the cytoplasm. Additionally, microtubules are the main components of eukaryotic flagella and cilia, composing both the filament and the basal body components ( Figure 3.54 ). 27 E. Fuchs, D.W. Cleveland. “A Structural Scaffolding of Intermediate Filaments in Health and Disease.” Science 279 no. 5350 (1998):514–519. In addition, microtubules are involved in cell division, forming the mitotic spindle that serves to separate chromosomes during mitosis and meiosis. The mitotic spindle is produced by two centrosomes , which are essentially microtubule-organizing centers, at opposite ends of the cell. Each centrosome is composed of a pair of centrioles positioned at right angles to each other, and each centriole is an array of nine parallel microtubules arranged in triplets ( Figure 3.48 ). Check Your Understanding Compare and contrast the three types of cytoskeletal structures described in this section. Mitochondria The large, complex organelles in which aerobic cellular respiration occurs in eukaryotic cells are called mitochondria ( Figure 3.49 ). The term “mitochondrion” was first coined by German microbiologist Carl Benda in 1898 and was later connected with the process of respiration by Otto Warburg in 1913. Scientists during the 1960s discovered that mitochondria have their own genome and 70S ribosomes. The mitochondrial genome was found to be bacterial, when it was sequenced in 1976. These findings ultimately supported the endosymbiotic theory proposed by Lynn Margulis , which states that mitochondria originally arose through an endosymbiotic event in which a bacterium capable of aerobic cellular respiration was taken up by phagocytosis into a host cell and remained as a viable intracellular component. Each mitochondrion has two lipid membranes. The outer membrane is a remnant of the original host cell’s membrane structures. The inner membrane was derived from the bacterial plasma membrane. The electron transport chain for aerobic respiration uses integral proteins embedded in the inner membrane. The mitochondrial matrix , corresponding to the location of the original bacterium’s cytoplasm, is the current location of many metabolic enzymes. It also contains mitochondrial DNA and 70S ribosomes . Invaginations of the inner membrane, called cristae, evolved to increase surface area for the location of biochemical reactions. The folding patterns of the cristae differ among various types of eukaryotic cells and are used to distinguish different eukaryotic organisms from each other. Chloroplasts Plant cells and algal cells contain chloroplasts , the organelles in which photosynthesis occurs ( Figure 3.50 ). All chloroplasts have at least three membrane systems: the outer membrane, the inner membrane, and the thylakoid membrane system. Inside the outer and inner membranes is the chloroplast stroma , a gel-like fluid that makes up much of a chloroplast’s volume, and in which the thylakoid system floats. The thylakoid system is a highly dynamic collection of folded membrane sacs. It is where the green photosynthetic pigment chlorophyll is found and the light reactions of photosynthesis occur. In most plant chloroplasts, the thylakoids are arranged in stacks called grana (singular: granum), whereas in some algal chloroplasts , the thylakoids are free floating. Other organelles similar to mitochondria have arisen in other types of eukaryotes, but their roles differ. Hydrogenosomes are found in some anaerobic eukaryotes and serve as the location of anaerobic hydrogen production. Hydrogenosomes typically lack their own DNA and ribosomes. Kinetoplasts are a variation of the mitochondria found in some eukaryotic pathogens. In these organisms, each cell has a single, long, branched mitochondrion in which kinetoplast DNA, organized as multiple circular pieces of DNA, is found concentrated at one pole of the cell. Micro Connections Mitochondria-Related Organelles in Protozoan Parasites Many protozoans, including several protozoan parasites that cause infections in humans, can be identified by their unusual appearance. Distinguishing features may include complex cell morphologies, the presence of unique organelles, or the absence of common organelles. The protozoan parasites Giardia lamblia and Trichomonas vaginalis are two examples. G. lamblia , a frequent cause of diarrhea in humans and many other animals, is an anaerobic parasite that possesses two nuclei and several flagella. Its Golgi apparatus and endoplasmic reticulum are greatly reduced, and it lacks mitochondria completely. However, it does have organelles known as mitosomes , double-membrane-bound organelles that appear to be severely reduced mitochondria. This has led scientists to believe that G. lamblia’ s ancestors once possessed mitochondria that evolved to become mitosomes. T. vaginalis , which causes the sexually transmitted infection vaginitis, is another protozoan parasite that lacks conventional mitochondria. Instead, it possesses hydrogenosomes , mitochondrial-related, double-membrane-bound organelles that produce molecular hydrogen used in cellular metabolism. Scientists believe that hydrogenosomes, like mitosomes, also evolved from mitochondria. 28 28 N. Yarlett, J.H.P. Hackstein. “Hydrogenosomes: One Organelle, Multiple Origins.” BioScience 55 no. 8 (2005):657–658. Plasma Membrane The plasma membrane of eukaryotic cells is similar in structure to the prokaryotic plasma membrane in that it is composed mainly of phospholipids forming a bilayer with embedded peripheral and integral proteins ( Figure 3.51 ). These membrane components move within the plane of the membrane according to the fluid mosaic model. However, unlike the prokaryotic membrane, eukaryotic membranes contain sterols , including cholesterol, that alter membrane fluidity. Additionally, many eukaryotic cells contain some specialized lipids, including sphingolipids, which are thought to play a role in maintaining membrane stability as well as being involved in signal transduction pathways and cell-to-cell communication. Membrane Transport Mechanisms The processes of simple diffusion , facilitated diffusion , and active transport are used in both eukaryotic and prokaryotic cells. However, eukaryotic cells also have the unique ability to perform various types of endocytosis , the uptake of matter through plasma membrane invagination and vacuole/vesicle formation ( Figure 3.52 ). A type of endocytosis involving the engulfment of large particles through membrane invagination is called phagocytosis , which means “cell eating.” In phagocytosis, particles (or other cells) are enclosed in a pocket within the membrane, which then pinches off from the membrane to form a vacuole that completely surrounds the particle. Another type of endocytosis is called pinocytosis , which means “cell drinking.” In pinocytosis, small, dissolved materials and liquids are taken into the cell through small vesicles. Saprophytic fungi, for example, obtain their nutrients from dead and decaying matter largely through pinocytosis. Receptor-mediated endocytosis is a type of endocytosis that is initiated by specific molecules called ligands when they bind to cell surface receptors on the membrane. Receptor-mediated endocytosis is the mechanism that peptide and amine-derived hormones use to enter cells and is also used by various viruses and bacteria for entry into host cells. The process by which secretory vesicles release their contents to the cell’s exterior is called exocytosis . Vesicles move toward the plasma membrane and then meld with the membrane, ejecting their contents out of the cell. Exocytosis is used by cells to remove waste products and may also be used to release chemical signals that can be taken up by other cells. Cell Wall In addition to a plasma membrane, some eukaryotic cells have a cell wall . Cells of fungi, algae, plants, and even some protists have cell walls. Depending upon the type of eukaryotic cell, cell walls can be made of a wide range of materials, including cellulose (fungi and plants); biogenic silica, calcium carbonate, agar, and carrageenan (protists and algae); or chitin (fungi). In general, all cell walls provide structural stability for the cell and protection from environmental stresses such as desiccation, changes in osmotic pressure, and traumatic injury. 29 29 M. Dudzick. “Protists.” OpenStax CNX. November 27, 2013. http://cnx.org/contents/f7048bb6-e462-459b-805c-ef291cf7049c@1 Extracellular Matrix Cells of animals and some protozoans do not have cell walls to help maintain shape and provide structural stability. Instead, these types of eukaryotic cells produce an extracellular matrix for this purpose. They secrete a sticky mass of carbohydrates and proteins into the spaces between adjacent cells ( Figure 3.53 ). Some protein components assemble into a basement membrane to which the remaining extracellular matrix components adhere. Proteoglycans typically form the bulky mass of the extracellular matrix while fibrous proteins, like collagen , provide strength. Both proteoglycans and collagen are attached to fibronectin proteins, which, in turn, are attached to integrin proteins. These integrin proteins interact with transmembrane proteins in the plasma membranes of eukaryotic cells that lack cell walls. In animal cells, the extracellular matrix allows cells within tissues to withstand external stresses and transmits signals from the outside of the cell to the inside. The amount of extracellular matrix is quite extensive in various types of connective tissues, and variations in the extracellular matrix can give different types of tissues their distinct properties. In addition, a host cell’s extracellular matrix is often the site where microbial pathogens attach themselves to establish infection. For example, Streptococcus pyogenes , the bacterium that causes strep throat and various other infections, binds to fibronectin in the extracellular matrix of the cells lining the oropharynx (upper region of the throat). Flagella and Cilia Some eukaryotic cells use flagella for locomotion; however, eukaryotic flagella are structurally distinct from those found in prokaryotic cells. Whereas the prokaryotic flagellum is a stiff, rotating structure, a eukaryotic flagellum is more like a flexible whip composed of nine parallel pairs of microtubules surrounding a central pair of microtubules. This arrangement is referred to as a 9+2 array ( Figure 3.54 ). The parallel microtubules use dynein motor proteins to move relative to each other, causing the flagellum to bend. Cilia (singular: cilium ) are a similar external structure found in some eukaryotic cells. Unique to eukaryotes, cilia are shorter than flagella and often cover the entire surface of a cell; however, they are structurally similar to flagella (a 9+2 array of microtubules) and use the same mechanism for movement. A structure called a basal body is found at the base of each cilium and flagellum. The basal body, which attaches the cilium or flagellum to the cell, is composed of an array of triplet microtubules similar to that of a centriole but embedded in the plasma membrane. Because of their shorter length, cilia use a rapid, flexible, waving motion. In addition to motility, cilia may have other functions such as sweeping particles past or into cells. For example, ciliated protozoans use the sweeping of cilia to move food particles into their mouthparts, and ciliated cells in the mammalian respiratory tract beat in synchrony to sweep mucus and debris up and out of the lungs ( Figure 3.54 ). Check Your Understanding Explain how the cellular envelope of eukaryotic cells compares to that of prokaryotic cells. Explain the difference between eukaryotic and prokaryotic flagella. Clinical Focus Resolution Since amoxicillin has not resolved Barbara’s case of pneumonia, the PA prescribes another antibiotic, azithromycin, which targets bacterial ribosomes rather than peptidoglycan. After taking the azithromycin as directed, Barbara’s symptoms resolve and she finally begins to feel like herself again. Presuming no drug resistance to amoxicillin was involved, and given the effectiveness of azithromycin, the causative agent of Barbara’s pneumonia is most likely Mycoplasma pneumoniae . Even though this bacterium is a prokaryotic cell, it is not inhibited by amoxicillin because it does not have a cell wall and, therefore, does not make peptidoglycan. Go back to the previous Clinical Focus box.
business_ethics
Summary 5.1 The Relationship between Business Ethics and Culture Culture has a tremendous influence on ethics and its application in a business setting. In fact, we can argue that culture and ethics cannot be separated, because ethical norms have been established over time by and make sense to people who share the same background, language, and customs. For its part, business operates within at least two cultures: its organizational culture and the wider culture in which it was founded. When a business attempts to establish itself in a new environment, a third culture comes into play. With increasingly diverse domestic and global markets and the spread of consumerism, companies must consider the ethical implications of outsourcing production and resist the temptation to look the other way when their values are challenged by the reality of overseas supply or distribution chains. 5.2 Business Ethics over Time As a function of culture, ethics is not static but changes in each new era. Technology is a driving force in ethical shifts, as we can see in tracing changes from the age of mercantilism to the Industrial Revolution to the postindustrial era and the Information Age. Some of the most successful recent efforts to advance ethical practices have come from influences outside industry, including government regulation and consumer pressure. 5.3 The Influence of Geography and Religion Business is primarily about relationships—with employees, business partners, and customers and clients. Ethical standards and practices governing these relationships depend on the environment they exist in, an environment that, in turn, depends on additional factors such as geography and religion. Religion’s role in business is less certain today; we are perhaps more likely to see a universal, secular code of ethics develop than to see religion serve as common ground for different cultures to come together. 5.4 Are the Values Central to Business Ethics Universal? Any system of business ethics must consider the processes of enculturation and acculturation as well as the fact that ethical standards may shift depending on geography or time, even if certain underlying ethical values (e.g., prohibitions against lying, fraud, or murder) may remain constant. It is usually in a business’s best interest to promote human flourishing within the organization, providing comprehensive training along a humanistic business model, which applies the social sciences to ensure profitability and responsibility in an organization as well as happy, productive employees.
Chapter Outline 5.1 The Relationship between Business Ethics and Culture 5.2 Business Ethics over Time 5.3 The Influence of Geography and Religion 5.4 Are the Values Central to Business Ethics Universal? Introduction Ethics is a construct of considerable significance to human beings. Some suggest ethics emerged to allow families and clans to cooperate in harsh environments. Others point to its use in governing trade and commerce, even simple bartering. Still others say ethical behavior is wired into the cognitive structures of the brain, explaining why we find codes of ethics and morality in texts as diverse as the Code of Hammurabi (a Babylonian code of law nearly four thousand years old), the Bible, the Napoleonic Code, and The Analects of Confucius , all of which outline ways for people to live together in society. Whatever its origin, ethics has almost certainly existed throughout human time and varied with language, culture, history, and geography ( Figure 5.1 ). Are there underlying values that transcend time and place, however? If so, do the protocols of business ethics embody these values? For instance, we see respect for others in Dubai, where tea accompanies negotiations; in Tokyo, where formal words and bows come first; and in Lima, where polite inquiries about the family precede business. Is respect, therefore, a universal value? In short, to what degree is any code of business ethics conditioned by culture, time, and geography? Given that individuals are responsible only for their own behavior, is it possible for business ethics to be universal?
[ { "answer": { "ans_choice": 0, "ans_text": "A" }, "bloom": null, "hl_context": "In the West , we typically think of these beliefs in Western terms . This worldview explains the misunderstanding between Minuit , who assumed he was buying Manhattan , and the tribal leaders , who may have had in mind nothing of the sort but instead believed they were granting some use rights . The point is that a particular understanding of and approach to business are already givens in any particular culture . Businesspeople who work across cultures in effect have entered the theater in the middle of the movie , and often they must perform the translation work of business to put their understanding and approach into local cultural idioms . <hl> One example of this is the fact that you might find sambal chili sauce in an Indonesian McDonald ’ s in place of Heinz ketchup , but the restaurant , nevertheless , is a McDonald ’ s . <hl> To understand the influence of culture on business ethics , it is essential to understand the concepts of enculturation and acculturation . In its most basic anthropological sense , enculturation refers to the process by which humans learn the rules , customs , skills , and values to participate in a society . In other words , no one is born with culture ; all humans , regardless of their origin , have to learn what is considered appropriate behavior in their surrounding cultures . <hl> Whereas enculturation is the acquisition of any society ’ s norms and values , acculturation refers specifically to the cultural transmission and socialization process that stems from cultural exchange . <hl> The effects of this blending of cultures appear in both the native ( original ) culture and the host ( adopted ) culture . Historically , acculturation has often been the result of military or political conquest . Today , it also comes about through economic development and the worldwide reach of the media .", "hl_sentences": "One example of this is the fact that you might find sambal chili sauce in an Indonesian McDonald ’ s in place of Heinz ketchup , but the restaurant , nevertheless , is a McDonald ’ s . Whereas enculturation is the acquisition of any society ’ s norms and values , acculturation refers specifically to the cultural transmission and socialization process that stems from cultural exchange .", "question": { "cloze_format": "The fact that a McDonald’s in Indonesia might provide sambal chili sauce to its customers rather than ketchup is as an example of ________.", "normal_format": "What is the fact that a McDonald’s in Indonesia might provide sambal chili sauce to its customers rather than ketchup an example of?", "question_choices": [ "acculturation", "consumerism", "enculturation", "globalization" ], "question_id": "fs-idm336518320", "question_text": "The fact that a McDonald’s in Indonesia might provide sambal chili sauce to its customers rather than ketchup is as an example of ________." }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 0, "ans_text": "A" }, "bloom": null, "hl_context": "<hl> The major historical periods that have shaped business ethics are the age of mercantilism , the Industrial Revolution , the postindustrial era , the Information Age , and the age of economic globalization , to which the rise of the Internet contributed significantly . <hl> Each of these periods has had a different impact on ethics and what is considered acceptable business practice . <hl> Some economists believe there may even be a postglobalization phase arising from populist movements throughout the world that question the benefits of free trade and call for protective measures , like import barriers and export subsidies , to reassert national sovereignty . <hl> 13 In some ways , these protectionist reactions represent a return to the theories and policies that were popular in the age of mercantilism .", "hl_sentences": "The major historical periods that have shaped business ethics are the age of mercantilism , the Industrial Revolution , the postindustrial era , the Information Age , and the age of economic globalization , to which the rise of the Internet contributed significantly . Some economists believe there may even be a postglobalization phase arising from populist movements throughout the world that question the benefits of free trade and call for protective measures , like import barriers and export subsidies , to reassert national sovereignty .", "question": { "cloze_format": "Protecting owners’ interests was a common feature of ________.", "normal_format": "What was protecting owners’ interests a common feature of?", "question_choices": [ "the Industrial Revolution", "the Information Age", "the Dodd-Frank Act", "muckraking" ], "question_id": "fs-idm339582528", "question_text": "Protecting owners’ interests was a common feature of ________." }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 2, "ans_text": "C" }, "bloom": null, "hl_context": "<hl> By the time of the Industrial Revolution and postindustrial eras , Protestantism and its values of frugality , hard work , and simplicity ( the “ Protestant ethic ” ) had helped create a culture of individualism and entrepreneurship in the West , particularly in Great Britain and the United States . <hl> <hl> In fact , the Protestant work ethic , religion , and a commitment to hard work all are intertwined in the business history of both these countries . <hl> One example of this singular association is John D . Rockefeller , who , in the late nineteenth and early twentieth centuries , commanded the attention given today to Bill Gates and Warren Buffet as emblems of free enterprise . A major factor in the difference that geography and culture make in our ethical standards is the influence of religious practice . <hl> For example , just as the current debate over the redistribution of goods and services has Christian roots , so the Industrial Revolution in England and northern Europe looked to Protestant Christianity in particular for the values of frugality , hard work , industriousness , and simplicity . <hl> Until the seventeenth century , religion and ethics were nearly inseparable . Many believed that people could not be persuaded to do the right thing without the threat of eternal damnation . The Enlightenment ’ s attempt to peel religion away from ethics was short-lived , with even Kant acknowledging the need to base morality on something beyond the rationalism of his time .", "hl_sentences": "By the time of the Industrial Revolution and postindustrial eras , Protestantism and its values of frugality , hard work , and simplicity ( the “ Protestant ethic ” ) had helped create a culture of individualism and entrepreneurship in the West , particularly in Great Britain and the United States . In fact , the Protestant work ethic , religion , and a commitment to hard work all are intertwined in the business history of both these countries . For example , just as the current debate over the redistribution of goods and services has Christian roots , so the Industrial Revolution in England and northern Europe looked to Protestant Christianity in particular for the values of frugality , hard work , industriousness , and simplicity .", "question": { "cloze_format": "Values of Protestant Christianity were often used to justify ________.", "normal_format": "Values of Protestant Christianity were often used to justify which of the following?", "question_choices": [ "mercantilism", "Standard Oil’s overseas investments", "business success during the Industrial Revolution", "secular humanism" ], "question_id": "fs-idm343258608", "question_text": "Values of Protestant Christianity were often used to justify ________." }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 0, "ans_text": "A" }, "bloom": null, "hl_context": "<hl> If there is anything to be learned from these scandals , it is that organizations will succumb to ethics crises if they do not pay attention to their organizational culture and foster their employees ’ growth as moral beings . <hl> This is even more important in industries like banking that are more susceptible to unethical behavior because of the great sums of money that change hands . Compliance is important , but business managers must attempt to go above and beyond to clearly model and enforce the highest standards of ethical behavior .", "hl_sentences": "If there is anything to be learned from these scandals , it is that organizations will succumb to ethics crises if they do not pay attention to their organizational culture and foster their employees ’ growth as moral beings .", "question": { "cloze_format": "Businesses today are concerned with balancing profitability with responsibility. Therefore, they should ________.", "normal_format": "Businesses today are concerned with balancing profitability with responsibility. Therefore, what should they do?", "question_choices": [ "pay attention to culture", "go beyond compliance", "hire moral people", "hire outside consultants to monitor their supply chain." ], "question_id": "fs-idm338649520", "question_text": "Businesses today are concerned with balancing profitability with responsibility. Therefore, they should ________." }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 3, "ans_text": "D" }, "bloom": null, "hl_context": "<hl> Business ethics exists on three levels : the individual , the organizational , and the societal . <hl> At the organizational and societal levels , laws , regulations , and oversight can go a long way toward curtailing illegal activity . Business ethics motivates managers to ( 1 ) meet legal and industry governing and reporting requirements and ( 2 ) shape corporate culture so that corrupt practices such as bribery , embezzlement , and fraud have no place in the organization . In the ideal case , the organization ’ s culture never allows the latter , because scandals not only damage reputations but they make companies and countries much less attractive to investors . Corruption is expensive : According to the World Economic Forum , no less than $ 2 trillion is lost each year worldwide as a result of corruption , a staggering waste not just of resources but of credibility for business in general . 28", "hl_sentences": "Business ethics exists on three levels : the individual , the organizational , and the societal .", "question": { "cloze_format": "The levels upon which business ethics exists are ___.", "normal_format": "What are the levels upon which business ethics exists?", "question_choices": [ "compliance and governance", "federal, state, and local", "normative and descriptive", "individual, organizational, and societal" ], "question_id": "fs-idm351441104", "question_text": "What are the levels upon which business ethics exists?" }, "references_are_paraphrase": null } ]
5
5.1 The Relationship between Business Ethics and Culture Learning Objectives By the end of this section, you will be able to: Describe the processes of acculturation and enculturation Explain the interaction of business and culture from an ethical perspective Analyze how consumerism and the global marketplace might challenge the belief system of an organization It has been said that English is the language of money and, for that reason, has become the language of business, finance, trade, communication, and travel. As such, English carries with it the values and assumptions of its native speakers around the world. But not all cultures share these assumptions, at least not implicitly. The sick leave or vacation policies of a British investment bank, for instance, may vary greatly from those of a shoe manufacturer in Laos. Because business and capitalism as conducted today have evolved primarily from European origins and profits are measured against Western standards like the U.S. dollar, the ethics that emerges from them is also beholden primarily (but not exclusively) to Western conceptions of behavior. The challenge for business leaders everywhere is to draw out the values of local cultures and integrate the best of those into their management models. The opportunities for doing so are enormous given the growing impact of China, India, Russia, and Brazil in global commerce. The cultures of these countries will affect the dominant business model, possibly even defining new ethical standards. Business Encounters Culture To understand the influence of culture on business ethics, it is essential to understand the concepts of enculturation and acculturation. In its most basic anthropological sense, enculturation refers to the process by which humans learn the rules, customs, skills, and values to participate in a society. In other words, no one is born with culture; all humans, regardless of their origin, have to learn what is considered appropriate behavior in their surrounding cultures. Whereas enculturation is the acquisition of any society’s norms and values, acculturation refers specifically to the cultural transmission and socialization process that stems from cultural exchange. The effects of this blending of cultures appear in both the native (original) culture and the host (adopted) culture. Historically, acculturation has often been the result of military or political conquest. Today, it also comes about through economic development and the worldwide reach of the media. One of the earliest real estate deals in the New World exemplifies the complexity that results when different cultures, experiences, and ethical codes come into contact. No deed of sale remains, so it is difficult to tell exactly what happened in May 1626 in what is now Manhattan , but historians agree that some kind of transaction took place between the Dutch West India Company, represented by Pieter Minuit, the newly appointed director-general of the New Netherland colony, and the Lenape, a Native American tribe ( Figure 5.2 ). Which exact Lenape tribe is unknown; its members may have been simply passing through Manhattan and could have been the Canarsee, who lived in what is today southern Brooklyn. 1 Legend has it that the Dutch bought Manhattan island for $24 worth of beads and trinkets, but some historians believe the natives granted the Dutch only fishing and hunting rights and not outright ownership. Furthermore, the price, acknowledged as “sixty guilders” (about $1000 today), could actually represent the value of items such as farming tools, muskets, gun powder, kettles, axes, knives, and clothing offered by the Dutch. Clearly, the reality was more nuanced than the legend. 2 The “purchase” of Manhattan is an excellent case study of an encounter between two vastly different cultures, worldviews, histories, and experiences of reality, all within a single geographic area. Although it is a misconception that the native peoples of what would become the United States did not own property or value individual possession, it is nevertheless true that their approach to property was more fluid than that of the Dutch and of later settlers like the English, who regarded property as a fixed commodity that could be owned and transferred to others. These differences, as well as enforced taxation, eventually led to war between the Dutch and several Native American tribes. 3 European colonization only exacerbated hostilities and misunderstandings, not merely about how to conduct business but also about how to live together in harmony. Link to Learning For more information, read this article about the Manhattan purchase and the encounter between European and Native American cultures and also this article about Peter Minuit and his involvement. What unexamined assumptions by both parties led to problems between them? Two major conditions affect the relationship between business and culture . The first is that business is not culturally neutral. Today, it typically displays a mindset that is Western and primarily English-speaking and is reinforced by the enculturation process of Western nations, which tends to emphasize individualism and competition. In this tradition, business is defined as the exchange of goods and services in a dedicated market for the purpose of commerce and creating value for its owners and investors. Thus, business is not open ended but rather directed toward a specific goal and supported by beliefs about labor, ownership, property, and rights. In the West, we typically think of these beliefs in Western terms. This worldview explains the misunderstanding between Minuit, who assumed he was buying Manhattan, and the tribal leaders, who may have had in mind nothing of the sort but instead believed they were granting some use rights. The point is that a particular understanding of and approach to business are already givens in any particular culture. Businesspeople who work across cultures in effect have entered the theater in the middle of the movie, and often they must perform the translation work of business to put their understanding and approach into local cultural idioms. One example of this is the fact that you might find sambal chili sauce in an Indonesian McDonald’s in place of Heinz ketchup, but the restaurant, nevertheless, is a McDonald’s. The second condition that affects the relationship between business and culture is more complex because it reflects an evolving view of business in which the purpose is not solely generating wealth but also balancing profitability and responsibility to the public interest and the planet. In this view, which has developed as a result of political change and economic globalization , organizations comply with legal and economic regulations but then go beyond them to effect social change and sometimes even social justice. 4 The dominant manufacture-production-marketing-consumption model is changing to meet the demands of an increasing global population and finite resources. No longer can an organization maintain a purely bottom-line mentality; now it must consider ethics, and, therefore, social responsibility and sustainability, throughout its entire operation. As a result, local cultures are assuming a more aggressive role in defining their relationship with business prevalent in their regions. Had this change taken place four centuries ago, that transaction in Manhattan might have gone a little differently. However, working across cultures can also create challenging ethical dilemmas, especially in regions where corruption is commonplace. A number of companies have experienced this problem, and globalization will likely only increase its incidence. Cases from the Real World Petrobras If you were to do a top-ten list of the world’s greatest corruption scandals, the problems of Petrobras ( Petróleo Brasileiro ) in Brazil surely would make the list. The majority state-owned petroleum conglomerate was a party to a multibillion-dollar scandal in which company executives received bribes and kickbacks from contractors in exchange for lucrative construction and drilling contracts. The contractors paid Petrobras executives upward of five percent of the contract amount, which was funneled back into slush funds. The slush funds, in turn, paid for the election campaigns of certain members of the ruling political party, Partido dos Trabalhadores , or Workers Party, as well as for luxury items like race cars, jewelry, Rolex watches, yachts, wine, and art. 5 The original investigation, known as Operation Car Wash ( Lava Jato) , began in 2014 at a gas station and car wash in Brasília, where money was being laundered. It has since expanded to include scrutiny of senators, government officials, and the former president of the republic, Luiz Inácio Lula da Silva. The probe also contributed to the impeachment and removal of Lula’s successor, Dilma Rousseff. Lula and Rousseff are members of the Workers Party. The case is complex, revealing Chinese suppliers, Swiss bank accounts where money was hidden from Brazilian authorities, and wire transfers that went through New York City and caught the eye of the U.S. Department of Justice. In early 2017, the Brazilian Supreme Court justice in charge of the investigation and prosecution was mysteriously killed in a plane crash. It is hard to imagine a more tragic example of systemic breakdown and individual vice. The loss of trust in government and the economy still affects ordinary Brazilians. Meanwhile, the investigation continues. Critical Thinking Is there any aspect of the case where you think preventive measures could have been taken either by management or government? How would they have worked? Do you think this case represents an example of a culture with different business ethics than those practiced in the United States? Why or why not? How might corporations with international locations adjust for this type of issue? Link to Learning Read this article about the Petrobras case to learn more. Balancing Beliefs What about the ethical dimensions of a business in a developed country engaging in commerce in an environment where corruption might be more rampant than at home? How can an organization remain true to its mission and what it believes about itself while honoring local customs and ethical standards? The question is significant because it goes to the heart of the organization’s values, its operations, and its internal culture. What must a business do to engage with local culture while still fulfilling its purpose, whether managers see that purpose as profitability, social responsibility, or a balance between the two? Most business organizations hold three kinds of beliefs about themselves. The first identifies the purpose of business itself. In recent years, this purpose has come to be the creation not just of shareholder wealth but also of economic or personal value for workers, communities, and investors. 6 The second belief defines the organization’s mission , which encapsulates its purpose. Most organizations maintain some form of mission statement. For instance, although IBM did away with its formal mission statement in 2003, its underlying beliefs about itself have remained intact since its founding in 1911. These are (1) dedication to client success, (2) innovation that matters (for IBM and the world), and (3) trust and personal responsibility in all relationships. 7 President and chief executive officer (CEO) Ginni Rometty stated the company “remain[s] dedicated to leading the world into a more prosperous and progressive future; to creating a world that is fairer, more diverse, more tolerant, more just.” 8 Link to Learning Johnson & Johnson was one of the first companies to write a formal mission statement, and it is one that continues to earn praise. This statement has been embraced by several succeeding CEOs at the company, illustrating that a firm’s mission statement can have a value that extends beyond its authors to serve many generations of managers and workers. Read Johnson & Johnson’s mission statement to learn more. Finally, businesses also go through the process of enculturation ; as a result, they have certain beliefs about themselves, drawn from the customs, language, history, religion, and ethics of the culture in which they are formed. One example of a company whose ethics and ethical practices are deeply embedded in its culture is Merck & Co., one of the world’s largest pharmaceutical companies and known for its strong ethical values and leadership. As its founder George W. Merck (1894–1957) once stated, “We try to remember that medicine is for the patient. We try never to forget that medicine is for the people. It is not for the profits. The profits follow, and if we have remembered that, they have never failed to appear. The better we have remembered it, the larger they have been.” 9 Culture is deeply rooted, but businesses may make their own interpretations of its accepted norms. Link to Learning Merck & Co. is justly lauded for its involvement in the fight to control the spread of river blindness in Africa. For more information, watch this World Bank video about Merck & Co.’s efforts to treat river blindness and its partnership with international organizations and African governments. Our beliefs are also challenged when a clash occurs between a legal framework and cultural norms, such as when a company feels compelled to engage in dubious and even illegal activities to generate business. For example, the German technology company Siemens has paid billions of dollars in fines and judgments for bribing government officials in several countries. Although some local officials may have expected to receive bribes to grant government contracts, Siemens was still bound by national and international regulations forbidding the practice, as well as by its own code of ethics. How can a company remain true to its mission and code of ethics in a highly competitive international environment ( Figure 5.3 )? Business performance is a reflection of what an organization believes about itself, as in the IBM and Merck examples. 10 Those beliefs, in turn, spring from what the individuals in the organization believe about it and themselves, based on their communities, families, personal biographies, religious beliefs, and educational backgrounds. Unless key leaders have a vision for the organization and themselves, and a path to achieving it, there can be no balance of beliefs about profitability and responsibility, or integration of business with culture. The Manhattan purchase was successful to the degree that Minuit and the tribal leaders were willing to engage in an exchange of mutual benefit. Yet this revealed a transaction between two very different commercial cultures. Did each group truly understand the other’s perception of an exchange of goods and services? Furthermore, did the parties balance personal and collective beliefs for the greater good? Given the distinctions between these two cultures, would that even have been possible? Consumerism and the Global Marketplace To paraphrase the ancient Greek philosopher Heraclitus (c. 535–475 BCE), the one constant in life is change. Traditional norms and customs have changed as the world’s population has grown more diverse and urbanized, and as the Internet has made news and other resources readily available. The growing emphasis on consumerism —a lifestyle characterized by the acquisition of goods and services—has meant that people have become defined as “consumers” as opposed to citizens or human beings. Unfortunately, this emphasis eventually leads to the problem of diminishing marginal utility, with the consumer having to buy an ever-increasing amount to reach the same level of satisfaction. At the same time, markets have become more diverse and interconnected. For example, South Korean companies like LG and Samsung employ 52,000 workers in the United States, 11 and many U.S. companies now manufacture their products abroad. Such globalization of their domestic markets has allowed U.S. consumers to enjoy products from around the world, but it also presents ethical challenges. The individual consumer, for instance, may benefit from lower prices and a greater selection of goods, but only by supporting a company that might be engaged in unethical practices in its overseas supply or distribution chains. Producers’ choices about wages, working conditions, environmental impact, child labor, taxation, and plant safety feature in the creation of each product brought to market. Becoming aware of these factors requires consumers to engage in an investigation of the business practices of those parties they will patronize and exercise a certain amount of cultural and ethical sensitivity. Cases from the Real World Overseas Manufacturing How can the purchase of a pair of sneakers be seen as an ethical act? Throughout the 1990s, the U.S. shoe and sportswear manufacturer Nike was widely criticized for subcontracting with factories in China and Southeast Asia that were little more than sweatshops with deplorable working conditions. After responding to the criticisms and demanding that its suppliers improve their workplaces, the company began to redeem itself in the eyes of many and has become a model of business ethics and sustainability. However, questions remain about the relationship between business and government. For instance, should a company advocate for labor rights, a minimum wage, and unionization in developing countries where it has operations? What responsibility does it have for the welfare of a contractor’s workers in a culture with differing customs? What right does any Western company have to insist that its foreign contractors observe in their factories the protocols required in the West? What, for example, is sacred about an eight-hour workday? When Nike demands that foreign manufacturers observe Western laws and customs about the workplace, arguably this is capitalist imperialism. Not only that, but Western firms will be charged more for concessions regarding factory conditions. Perhaps this is as it should be, but Western consumers must then be prepared to pay more for material goods than in the past. Some argue that demanding that companies accept these responsibilities imposes cultural standards on another culture through economic pressure. Others insist there should be universal standards of humane employee treatment, and that they must be met regardless of where they come from or who imposes them. But should the market dictate such standards, or should the government? The rise of artificial intelligence and robotics will complicate this challenge because, in time, they may make offshoring the manufacture and distribution of goods unnecessary. It may be cheaper and more efficient to bring these operations back to developed countries and use robotic systems instead. What would that mean for local cultures and their economies? In Nike’s case, automation is already a concern, particularly as competition from its German rival, Adidas, heats up again. 12 Critical Thinking What ethical responsibilities do individual consumers have when dealing with companies that rely on overseas labor? Should businesses adopt universal workplace standards about working conditions and employee protections? Why or why not? What would be required for consumers to have the necessary knowledge about a product and how it was made so that they could make an informed and ethical decision? The media? Commercial watchdog groups? Social-issues campaigns? Something else? Link to Learning Read this report, “A Race to the Bottom: Trans-Pacific Partnership and Nike in Vietnam,” to learn more about this issue. In considering the ethical challenges presented by the outsourcing of production to lower costs and increase profits, let us return to the example of IBM. IBM has a responsibility to provide technology products of high quality at affordable prices in line with its beliefs about client success, innovation, and trust. If it achieved these ends in a fraudulent or otherwise illegal way, it would be acting irresponsibly and in violation of both U.S. and host country laws and as well as the company’s own code of ethics. These constraints appear to leave little room for unethical behavior, yet in a globalized world of intense competition, the temptation to do anything possible to carve out an advantage can be overpowering. This choice between ends and means is reminiscent of the philosophers Aristotle and Kant, both of whom believed it impossible to achieve just ends through unjust means. But what about consumer responsibility and the impact on the global community? Western consumers tend to perceive globalization as a phenomenon intended to benefit them specifically. In general, they have few compunctions about Western businesses offshoring their manufacturing operations as long as it ultimately benefits them as consumers. However, even in business, ethics is not about consumption but rather about human morality, a greater end. Considering an expansion of domestic markets, what feature of this process enables us to become more humane rather than simply pickier consumers or wasteful spenders? It is the opportunity to encounter other cultures and people, increasing our ethical awareness and sensitivity. Seen in this way, globalization affects the human condition. It raises no less a question than what kind of world we want to leave to our children and grandchildren. 5.2 Business Ethics over Time Learning Objectives By the end of this section, you will be able to: Describe the ways ethical standards change over time Identify major shifts in technology and ethical thinking over the last five hundred years Explain the impact of government and self-imposed regulation on ethical standards and practices in the United States Besides culture, the other major influence in the development of business ethics is the passage of time. Ethical standards do not remain fixed; they transform in response to evolving situations. Over time, people change, technology advances, and cultural mores (i.e., acquired culture and manners) shift. What was considered an appropriate or accepted business practice one hundred or even fifty years ago may not carry the same moral weight it once did. However, this does not mean ethics and moral behavior are relative. It simply acknowledges that attitudes change in relationship to historical events and that cultural perspective and the process of acculturation are not stagnant. Shifts in Cultural and Ethical Standards We find an example of changing cultural mores in the fashion industry, where drastic evolution can occur even over ten years, let alone a century. The changes can be more than simply stylistic ones. Clothing reflects people’s view of themselves, their world, and their values. A woman in the first half of the twentieth century might be very proud to wear a fox stole with its head and feet intact ( Figure 5.4 ). Today, many would consider that an ethical faux pas, even as the use of fur remains common in the industry despite active campaigns against it by organizations such as People for the Ethical Treatment of Animals. At the same time, cosmetics manufacturers increasingly pledge not to test their products on animals, reflecting changing awareness of animals’ rights. Bias is built into the human psyche and expressed through our social structures. For this reason, we should avoid making snap judgments about past eras based on today’s standards. The challenge, of course, is to know which values are situational—that is, although many values and ethics are relative and subjective, others are objectively true, at least to most people. We can hardly argue in favor of slavery, for example, no matter in which culture or historical era it was practiced. Of course, although some values strike us as universal, the ways in which they are interpreted and applied vary over time, so that what was once acceptable no longer is, or the reverse. Ethics Across Time and Cultures When Even Doctors Smoked From the 1940s to the 1970s, cigarettes were as common as water bottles are today. Nearly everyone smoked, from judges in court to factory workers and pregnant women. Edward Bernays, the Austrian-American founder of the field of public relations, promoted smoking among women in a 1929 campaign in New York City in which he marketed Lucky Strike cigarettes as “torches of freedom” that would lead to equality between men and women. However, by the late 1960s, and in the wake of the release of the landmark Surgeon General’s report on “Smoking and Health” on January 11, 1964, it had become clear that there was a direct link between cigarette smoking and lung cancer. Subsequent research has added heart and lung diseases, stroke, and diabetes. Smoking has decreased in Western countries but remains well established in the global East and South, where cigarette manufacturers actively promote the products in markets like Brazil, China, Russia, and Singapore, especially among young people. Critical Thinking Are such practices ethical? Why or why not? Link to Learning Explore these statistics on cigarette smoking in young adults from the CDC and these charts on the global state of smoking from the World Bank for information about cigarette use in the United States and globally, including demographic breakdowns of smoking populations. Thus, we acknowledge that different eras upheld different ethical standards, and that each of these standards has had an impact on our understanding of ethics today. But this realization raises some basic questions. First, what should we discard and what should we keep from the past? Second, on what basis should we make this decision? Third, is history cumulative, progressing onward and upward through time, or does it unfold in different and more complicated ways, sometimes circling back upon itself? The major historical periods that have shaped business ethics are the age of mercantilism, the Industrial Revolution, the postindustrial era, the Information Age, and the age of economic globalization, to which the rise of the Internet contributed significantly. Each of these periods has had a different impact on ethics and what is considered acceptable business practice. Some economists believe there may even be a postglobalization phase arising from populist movements throughout the world that question the benefits of free trade and call for protective measures, like import barriers and export subsidies, to reassert national sovereignty. 13 In some ways, these protectionist reactions represent a return to the theories and policies that were popular in the age of mercantilism. Unlike capitalism, which views wealth creation as the key to economic growth and prosperity, mercantilism relies on the theory that global wealth is static and, therefore, prosperity depends on extracting wealth or accumulating it from others. Under mercantilism, from the sixteenth to the eighteenth centuries, the exploration of newly opened markets and trade routes coincided with the impulse to colonize, producing an ethical code that valued acculturation by means of trade and often brute force. European powers extracted raw commodities like cotton, silk, diamonds, tea, and tobacco from their colonies in Africa, Asia, and South America and brought them home for production. Few questioned the practice, and the operation of business ethics consisted mainly of protecting owners’ interests. During the Industrial Revolution and the postindustrial era, in the nineteenth and early twentieth centuries, business focused on the pursuit of wealth, the expansion of overseas markets, and the accumulation of capital. The goal was to earn as high a profit as possible for shareholders, with little concern for outside stakeholders. Charles Dickens (1812–1870) famously exposed the conditions of factory work and the poverty of the working class in many of his novels, as did the American writer Upton Sinclair (1878–1968). Although these periods witnessed extraordinary developments in science, medicine, engineering, and technology, the state of business ethics was perhaps best described by critics like Ida Tarbell (1857–1944), who said of industrialist John D. Rockefeller (1839–1937) ( Figure 5.5 ), “Would you ask for scruples in an electric dynamo?” 14 With the advent of the Information and Internet ages in the late twentieth and early twenty-first centuries, a code of professional conduct developed for the purpose of achieving goals through strategic planning. 15 In the past, ethical or normative rules were imposed from above to lead people toward right behavior, as the company defined it. Now, however, more emphasis is placed on each person at a firm embracing ethical standards and following those dictates to arrive at the appropriate behavior, whether at work or when off the clock. 16 The creation of human resources departments (increasingly now designated as human capital or human assets departments) is an outgrowth of this philosophy, because it reflects a view that humans have a unique value that ought not be reduced simply to the notion that they are instruments to be manipulated for the purposes of the organization. Millennia earlier, Aristotle referred to “living tools” in a similar but critical way. 17 Although one characteristic of the information age—access to information on an unprecedented scale—has transformed business and society (and some say made it more egalitarian), we must ask whether it also contributes to human flourishing, and to what extent business should concern itself with this goal. A Matter of Time What effect does time have on business ethics, and how is this effect achieved? If we accept that business today has two purposes—profitability and responsibility—we might assume that business ethics is in a much better position now than in the past to affect conduct across industries. However, much of the transformation of business over time has been the result of direct government intervention; one recent example is the Dodd–Frank Wall Street Reform and Consumer Protection Act that followed the financial crisis of 2008. Yet, despite such regulation and increased management vigilance in the form of ethics training, compliance reporting, whistleblower programs, and audits, it is tempting to conclude that business ethics is in worse shape than ever. The Information Age and the Internet may even have facilitated unethical behavior by making it easier to move large sums of money around undetected, by enabling the spread of misinformation on a global scale, and by exposing the public to the theft and misuse of vast stores of personal data gathered by companies as diverse as Equifax and Facebook. However, since the mercantile era, there has been a gradual increase in awareness of the ethical dimension of business. As we saw in the preceding chapter, businesses and the U.S. government have debated and litigated the role of corporate social responsibility throughout the twentieth century, first validating the rule of shareholder primacy in Dodge v. Ford Motor Company (1919) and then moving away from a strict interpretation of it in Shlensky v. Wrigley (1968). In Dodge v. Ford Motor Company (1919), the Michigan Supreme Court famously ruled that Ford had to operate in the interests of its shareholders as opposed to its employees and managers, which meant prioritizing profit and return on investment. This court decision was made even though Henry Ford had said, “My ambition is to employ still more men, to spread the benefits of this industrial system to the greatest possible number, to help them build up their lives and their homes. To do this we are putting the greatest share of our profits back in the business.” 18 By mid-century and the case of Shlensky v. Wrigley (1968), the courts had given boards of directors and management more latitude in determining how to balance the interests of stakeholders. 19 This position was confirmed in the more recent case of Burwell v. Hobby Lobby (2014), which held that corporate law does not require for-profit corporations to pursue profit at the expense of everything else. Governmental regulation and legal interpretations have not been the only avenues of change over the past century. The growing influence of consumers has been another driving force in recent attempts by businesses to self-regulate and voluntarily comply with global ethical standards that ensure basic human rights and working conditions. The United Nations (UN) Global Compact is one of these standards. Its mission is to mobilize companies and stakeholders to create a world in which businesses align their strategies and operations with a set of core principles covering human rights, labor, the environment, and anticorruption practices. The Global Compact is a “voluntary initiative based on CEO commitments to implement universal sustainability principles and to undertake partnerships in support of UN goals.” 20 Of course, as a voluntary initiative, the initiative does not bind corporations and countries to the principles outlined in it. Link to Learning Read the Ten Principles of the United Nations Global Compact urging corporations to develop a “principled approach to doing business.” The principles cover human rights, labor, the environment, and corruption. Whenever we look at the ways in which our perception of ethical business practice changes over time, we should note that such change is not necessarily good or bad but rather a function of human nature and of the ways in which our views are influenced by our environment, our culture, and the passage of time. Many of the examples discussed thus far illustrate a gradual increase in social awareness due to the actions of individual leaders and the historical era in which they found themselves. This does not mean that culture is irrelevant, but that human nature exists and ethical inclination is part of that nature. Historical conditions may allow this nature to be expressed more or less fully. We might measure ethical standards according to the degree they allow human compassion to direct business practice or, at least, make it easier for compassion to hold sway. We might then consider ethics not just a nicety but a constitutive part of business, because it is an inherent human trait. This is a perspective Kant and Rawls might have agreed with. Ethical thinking over time should be measured, deliberate, and open to examination. 5.3 The Influence of Geography and Religion Learning Objectives By the end of this section, you will be able to: Describe the impact of geography on global relationships and business ethics Explain how religion informs ethical business practice around the world Business ethics guides people to practice commerce professionally and honestly and in a way that permits as many as possible to flourish. However, as we have seen, the ethical standards by which business is conducted can vary depending on culture and time. Geography and regional cultural practices also play a significant role. As global markets become increasingly connected and interdependent, we navigate more of our valued relationships across international boundaries. Business as Global Relationships Global relationships teach us to be sensitive not just to other languages and customs but also to other people’s worldviews. A company looking to move its production to another country may be interested in setting up supply, distribution, and value chains that support human rights, worker safety, and equity for women, while the local culture is excited about the economic benefits it will gain from the company’s investment in employment and the local tax base and infrastructure. These goals need not be in conflict, but they must be integrated if the company is to reach an ethically sound agreement with the host country. Dialogue and openness are crucial to this process, just as they are in every other kind of relationship. Geography affects a business’s relationship with almost any type of stakeholder, from stockholders and employees to customers, the government, and the environment. Hence the growing importance of localization , the process of adapting a product for non-native environments and languages, especially other nations and cultures. Such adaption often starts with language translation but may include customizing content or products to the tastes and consumption habits of the local market; converting currencies, dates, and other measurements to regional standards; and addressing community regulations and legal requirements. Research has shown that successful leaders and organizations with global responsibilities “need to understand and exceed the leadership expectations in the cultures they are interacting with.” 21 In its study of leadership effectiveness and organizational behavior across cultures, the GLOBE leadership project of the Beedie School of Business at Simon Fraser University in Vancouver, Canada, found leader effectiveness is contextual and strongly connected to cultural and organizational values. The study also concluded that, although leaders learn to adapt to cultural expectations, they often have to exceed those expectations to be truly successful. 22 In other words, business has a role beyond merely reflecting the culture in which it operates. One element of business culture you may not realize is based on local custom and culture is the notion of time. Unlike the notion of historical time discussed in the previous module, the concept of time in business—people’s approach to punctuality, for example—varies widely in different cultures. To put it in economic terms, all cultures share the resource of time, but they measure and use that resource very differently. These differences might significantly affect the foundation of any business relationships you may want to establish around the world. For this and many other reasons, basic cultural literacy must be at the forefront of any ethical system that governs business behavior. Consider, for example, that in the United States, we might speak of “a New York minute,” “the nick of time,” “the eleventh hour,” and so on. Such expressions make sense in a culture where the enculturation process emphasizes competition and speed. But even among Western business cultures, conceptions of time can differ. For example, the Italian subito and the German sofort both refer to something happening “at once” or “straightaway,” but with different expectations about when the action, in fact, will take place. And some cultures do not measure the passage of time at all. Generally, the farther east and south we travel from the United States, the more time becomes relational rather than chronological. In Kenya, tutaonana baadaye means “see you later,” although “later” could be any time, open to context and interpretation. The nomadic inhabitants of North Africa known as the Tuareg sit down to tea before discussing any business, and as a rule, the longer the time spent in preliminary conversation, the better. A Tuareg proverb has it that the first cup of tea is bitter like life, the second sweet like love, and the third gentle like death. 23 Compare this with the Western attitude that “time flies” and “time is money.” Finally, Westerners doing business in some English-speaking African countries have learned that if they want something immediately, they have to say “now now” as “now” by itself does not convey the desired sense of immediacy. Another aspect of international business relationships is the question of personal space. In Nigeria, for example, standing either too close or too far from someone to whom you are speaking might be seen as impolite. In some cultures, touch is important in establishing connection, whereas in others it may be frowned upon. As a general rule, “contact” cultures—where people stand closer together when interacting, touch more often, and have more frequent direct eye contact—are found in South America, the Middle East, and southern Europe, while “noncontact” cultures—where eye contact and touching are less frequent, and there is less physical proximity during interactions—are in northern Europe, the Far East, and the United States. So, the seemingly innocuous gesture of a handshake to cement a new business relationship might be viewed very differently depending on where it occurs and who is shaking hands. All of this speaks to the awareness and cultural sensitivity that must be exhibited by an ethical manager doing business in a region different from his or her own. Certain mistakes, particularly accidental ones and those not motivated by malicious design, will likely be forgiven. Still, a global ethical demeanor requires that we be as conscious as possible as to what constitutes courtesy wherever we find ourselves conducting business. What Would You Do? Tucked In, Tucked Out Time and space are just two examples of cultural characteristics that you may take for granted but that are not universal. Business attire is another, as is humor, which is notoriously hard to translate across languages and cultures. And, of course, miscommunications can occur not just across regional boundaries and business cultures but even within them. For example, unless you are a barista at a hipster coffee bar, it may not be a good idea to wear piercings, tattoos, or colorfully dyed hair to work. Employers have the right to establish a dress code and expect employees to abide by it. In the movie The Intern , Robert De Niro’s senior character wears conservative blue and gray suits to his job at an e-commerce fashion startup, whereas the younger men dress very casually. At one point in the film, De Niro’s character asks, “Doesn’t anybody tuck in their shirt?” Leaving your shirt untucked has become more acceptable in recent years, and the black t-shirt and jeans favored in Silicon Valley are now quite fashionable in some business environments. Many today would disagree with the old adage that “clothes make the man,” yet studies show that well-dressed employees are held in higher esteem and may earn more, on average, than those who dress down. The age of uncomfortable dresses and starched white shirts may be over, but cultural standards, along with underlying values that prioritize, say, innovation over uniformity, change over time and even within the same company. Critical Thinking How do you think clothing choices affect the relationships we form at work or in other business situations? What is your opinion about workplace dress codes, and how far should employers go in setting dress and other behavior standards? Why are these standards important (or not) from an ethical perspective? How do you think clothing might affect an international company’s approach to business ethics? Link to Learning The Italian Jesuit priest Matteo Ricci (1552–1610) learned Mandarin, adopted Chinese dress, translated Confucian texts into Latin, and was welcomed into the Chinese emperor’s court as a scholar. His message was religious, not commercial, but his respectful attitude allowed him to be accepted and trusted by the emperor and administrators. Learn more about Ricci’s approach and the relationship between Western and Ming Chinese views of ethics on this webpage. Religion and Ethics A major factor in the difference that geography and culture make in our ethical standards is the influence of religious practice. For example, just as the current debate over the redistribution of goods and services has Christian roots, so the Industrial Revolution in England and northern Europe looked to Protestant Christianity in particular for the values of frugality, hard work, industriousness, and simplicity. Until the seventeenth century, religion and ethics were nearly inseparable. Many believed that people could not be persuaded to do the right thing without the threat of eternal damnation. The Enlightenment’s attempt to peel religion away from ethics was short-lived, with even Kant acknowledging the need to base morality on something beyond the rationalism of his time. Religions are neither uniform nor monolithic, of course, nor are they unchanging over time. The core of Christianity, for instance, does not change, but its emphasis in any given period does. Moreover, the state or crown often worked side by side with the church in the past, choosing certain teachings over others to promote its own interests. This cooperation was evident during the era of mercantilism when the issue of personhood, or the privilege of having the freedom and capacity to make decisions and act morally, was hotly debated in the context of slavery, a practice that had been going on for centuries in the Christian West and the Islamic East. Although the church officially opposed slavery, the conquest of new lands was justified theologically as bringing salvation and civilization to populations considered savage and unsophisticated. Christianity was thought to save them from their pagan ways just as Islam and the message of the prophet saved unbelievers in the East. Behavioral norms for the clergy were founded and supported by the divine right of kings and the authority of religious tradition ( Figure 5.6 ). Commerce and trade followed these norms. By the time of the Industrial Revolution and postindustrial eras, Protestantism and its values of frugality, hard work, and simplicity (the “Protestant ethic”) had helped create a culture of individualism and entrepreneurship in the West, particularly in Great Britain and the United States. In fact, the Protestant work ethic, religion, and a commitment to hard work all are intertwined in the business history of both these countries. One example of this singular association is John D. Rockefeller , who, in the late nineteenth and early twentieth centuries, commanded the attention given today to Bill Gates and Warren Buffet as emblems of free enterprise. No one was more convinced of the link between religious faith and success in business than Rockefeller, who clung to his Baptist faith from his early years until his death in 1937. The richest person of his age, Rockefeller earned his fortune as the founder and major shareholder of Standard Oil but always regarded his billions as a public trust rather than his personal prize. “As his fortune grew big enough to beggar the imagination, [Rockefeller] retained his mystic faith that God had given him money for mankind’s benefit . . . or else why had He lavished such bounty on him?” 24 Despite criticism, even from family members, Rockefeller donated enormous sums to many causes, especially medical research (in the form of Rockefeller University) and higher education. He financed the founding of the University of Chicago as an institution that would train students to pursue their professional and business interests under the guidance of Christian faith. Still, as Ida Tarbell pointed out in her work, Rockefeller’s business ethics were not above reproach. In making his fortune, he pursued markedly Darwinian practices revealing a conviction in survival of the fittest. Later in life, and as his philanthropic motivation increased, his endowment of several charitable causes more fully reflected his belief as to how God wished him to dispose of a sizable portion of his wealth. Link to Learning Watch this episode of “American Experience” on John D. Rockefeller, Sr. from the Public Broadcasting System to learn more about him. Of course, Rockefeller’s concept of stewardship—an attitude toward money and capital that stresses care and responsibility rather than pure utility—can be found across cultures and religions in various forms, and there are many similarities among the Judaic, Islamic, and Christian views of money and its use toward a greater end. All three of these religions teach that no harm should be done to others, nor should people be treated as means toward a material end like wealth. Yet what role does a religious concept of stewardship play in the ethics of the twenty-first century? The Enlightenment attempted to separate religion and ethics but could not. Are the two concepts inextricably linked? Might the business leaders of today succeed where the Enlightenment failed? Although religious practices and cultural assumptions remain strongly in place, fewer people in the West today profess a religion than in the past. 25 Does this development affect the way you approach business relationships and conduct negotiations? Might we see a universal, secular code of ethics developing in place of religion? If so, how would it accommodate the differences across time, regions, and cultures discussed in this chapter? The Universal Declaration of Human Rights, adopted by the United Nations General Assembly in December 1948, contains a list of basic human rights such as the right to life, liberty, due process, religion, education, marriage, and property. Business ethics will have to balance all these factors when adopting standards of conduct and local practices. What Would You Do? Ramadan Jillian Armstrong leads an external audit team reviewing the financial statements of Islamabad Investment Bank in Islamabad, Pakistan. It is Ramadan, and the employees on her team are Muslims who fast each day for a month. Jillian has never fasted and believes the practice can be harmful over prolonged periods, especially in the heat of summer. She proposes several times that team members keep up their strength by drinking water or tea, but her suggestions are met with awkward silence. She has decided to leave well enough alone as long as everyone does their work, but now she faces a dilemma. What should she do for lunch? Should she eat in her office, out of sight of the team and bank employees? Have lunch in one of the local restaurants that cater to Westerners? Or perhaps fast with her team and eat at sundown? Critical Thinking What do you think would be the effect of Jillian’s accepting the local custom but continuing her own personal preference at mealtimes? Can two ways of life exist side by side at work? Why or why not? 5.4 Are the Values Central to Business Ethics Universal? Learning Objectives By the end of this section, you will be able to: Explain the difference between relative and absolute ethical values Discuss the degree to which compliance is linked with organizational responsibility and personal values Identify the criteria for a system of normative business ethics Evaluate the humanistic business model One of the perennial themes in business ethics—indeed, in ethics in general—is the difference between relative and absolute values. Is it possible to identify a set of universal values that is consistent across cultures and time? We might begin with always honoring the terms of a contract, consistently treating customers and partners with honesty, and never cheating. Where could we go from there? No matter our culture, geography, or time, could we identify some basic normative behaviors to govern business conduct in general? Absolute Values versus Relative Values To put this question another way, is there a set of universal values that all can endorse? Are there “human values” that apply everywhere despite differences in time, place, and culture ( Figure 5.7 )? If not, and if ethical standards are relative, are they worth having? Again, the UN Universal Declaration of Human Rights is a useful starting point for the way business can conduct itself. Let us look at how it is possible to align business with human rights in such a way that both profitability and responsibility are honored across the globe. According to the Union Internationale des Avocats, an international, nongovernmental association of legal professionals, corruption “corrodes the democratic principles of accountability, equality, and transparency. It poses an extremely high cost to the citizenry, it saps the credibility of government and it places companies under an unbearable economic burden.” 26 The UN Convention Against Corruption has called corruption “an insidious plague” that exists everywhere and “hurts the poor disproportionately by diverting funds intended for development, undermining a Government’s ability to provide basic services, feeding inequality and injustice and discouraging foreign aid and investment.” 27 Corruption appears to exist everywhere, so it would seem to require a persistent and consistent answer everywhere. Can business ethics provide one? Business ethics exists on three levels: the individual, the organizational, and the societal. At the organizational and societal levels, laws, regulations, and oversight can go a long way toward curtailing illegal activity. Business ethics motivates managers to (1) meet legal and industry governing and reporting requirements and (2) shape corporate culture so that corrupt practices such as bribery, embezzlement, and fraud have no place in the organization. In the ideal case, the organization’s culture never allows the latter, because scandals not only damage reputations but they make companies and countries much less attractive to investors. Corruption is expensive: According to the World Economic Forum, no less than $2 trillion is lost each year worldwide as a result of corruption, a staggering waste not just of resources but of credibility for business in general. 28 At the individual level, when corruption takes place, it is a matter of conscience. Corruption can be defeated only by individuals acting in accordance with their conscience and being supported by systems and corporate culture that encourage such action. Transparency, whistleblower programs, ethics training, and modeling of appropriate behavior by upper management can create the conditions for employees to act ethically, but conscience is a personal phenomenon. So, although the work of national, regional, and international organizations can limit corruption through enforcement and the prosecution of cases (as was the case with the revelation of the so-called Panama Papers), corruption will not be reduced in any significant way unless efforts have been made to form individual conscience and teach practical ways to act on it. Link to Learning Read the article “Perspective: Panama Papers and ‘responsible’ journalism” on the Panama Papers and how journalists might hold the corporate world to account in cases of fraud and corruption for a detailed explanation. Although ethical practice has been directly influenced by religion , as noted, ethics is not religion and religious belief is not a prerequisite for a commitment to business ethics. For example, although what constitutes ethical behavior in Islamic society is strongly linked to religious values, secular philosophers can endorse a highly developed commitment to commercial ethics, too. Furthermore, most religions have high ethical standards but do not address many of the problems faced in business. And although a good system of law incorporates ethical standards, the law can and sometimes does deviate from what is ethical. Finally, in the same vein, ethics is not science. The social and natural sciences provide data to make better ethical choices, but science cannot tell people what they ought to do (nor should it). Absolute values do exist. Abstaining from cheating customers, defrauding clients, lying, and murder are fairly objective ethical values; the reason for making any exceptions must be carefully laid out. Ethical systems, whether utilitarian, rights based, or based on natural law and virtue ethics, are attempts to translate absolute values like these into workable solutions for people. From these systems has emerged a basic set of ethical norms for the business world. Business Ethics and Compliance A hallmark of any profession is the existence of ethical guidelines, often based on values like honesty, integrity, and objectivity. Organizational responsibility is fairly straightforward: Comply with applicable local, state, national, and international regulations. Compliance can be an immense task for industries like aerospace, pharmaceuticals, banking, and food production, due to the large number of employees involved, the certification of them that sometimes is necessary, and the requisite record keeping. Still, legal requirements are usually clear, as are the ways an organization can exceed them (as do, for example, companies such as Whole Foods, Zappos, and Starbucks). Personal responsibility is a different matter. It is either less clear what to do or harder to do it because of constant pressure to increase the organization’s profitability and the perception that “everybody else is doing it.” 29 In the United States, companies spend more than $70 billion annually on ethics training; worldwide, the figure is more than double that. 30 Unfortunately, in the United States, much of this money is spent on merely meeting the minimum requirements of compliance, so that if there is ever a problem with the Department of Justice or the Securities and Exchange Commission, the organization is insulated from criticism or liability because its employees have engaged in the recommended training. Federal Sentencing Guidelines for felonies and serious misdemeanors now carry mandatory prison time for individual executives who are convicted. These guidelines also are designed to help organizations with compliance and reporting, and they introduce seven steps toward that end: (1) create a Code of Ethics, (2) introduce high-level oversight, (3) place ethical people in positions of authority, (4) communicate ethics standards, (5) facilitate employee reporting of misconduct, (6) react and respond to instances of misconduct, and (7) take preventive steps. Many organizations focus on the letter of the law so that they can claim “good faith” in their effort to create an ethical environment. However, middle managers and employees often complain their ethics training consists of passing a computerized sexual harassment or fraud program once a year but that nothing is done to address issues in a substantive way or to change the culture of the organization, even those that have experienced problems. 31 The focus still seems to be on organizational responsibility and compliance as opposed to individual responsibility and the formation of ethical conscience. We might argue that it is not the business of business to form people in their conscience, but the result of not doing so has become expensive for everyone concerned. 32 The damage done to an organization’s or government’s reputation due to scandal can be enormous and long lasting. The 2017 conviction for bribery and embezzlement of Lee Jae-yong, heir to the Samsung electronics empire, was part of a widespread corruption scandal that brought down the president of South Korea. Bribery was also at the heart of the FIFA (Fédération Internationale de Football Association) corruption scandal, in which soccer officials, marketing executives, and broadcasters were accused of racketeering, wire fraud, and money laundering by the U.S. Department of Justice in 2015. The Volkswagen emissions scandal also began in 2015, when the Environmental Protection Agency cited the German automaker for violating the Clean Air Act by cheating on emissions tests. To date, the fallout has cost the company nearly $30 billion in fines. As the LIBOR (London Interbank Offered Rate) scandal, in which banks were manipulating rates to profit from trades, showed, ethical breakdowns often occur because systems fail or people make bad decisions, and sometimes both. In the case of LIBOR, the United Kingdom’s Serious Fraud Office determined there were inadequate systems of oversight in the setting of rates and that individual executives encouraged rate fixing, which led to the conviction of several traders, at least one of whom still maintains his innocence. 33 The result was a staggering $6 billion cumulative fine for the banks involved (i.e., Barclay’s, J.P. Morgan Chase, Citicorp, Royal Bank of Scotland, and Deutsche Bank). 34 Link to Learning Read this article on the LIBOR scandal and the consequences for an in-depth overview. If there is anything to be learned from these scandals, it is that organizations will succumb to ethics crises if they do not pay attention to their organizational culture and foster their employees’ growth as moral beings. This is even more important in industries like banking that are more susceptible to unethical behavior because of the great sums of money that change hands. Compliance is important, but business managers must attempt to go above and beyond to clearly model and enforce the highest standards of ethical behavior. Normative Business Ethics Normative business ethics should address systemic issues such as oversight and transparency as well as the character of individuals who make up the organization. Human flourishing may not be the immediate concern of business, but managers and employees have a significant impact on business performance. Giving employees common-sense advice and training in practical ways to counter unethical behavior, as well as ethical role models at the top of the organization, can be more effective than prevention. There are programs that do this, such as “Giving Voice to Values” at the Darden School of Business at the University of Virginia. 35 These programs are effective for their ability to help individuals act on their principles. As effective as they may be, however, they beg the larger question not of how someone can act on what their conscience tells them but how to determine what their conscience is telling them in the first place. One model of ethical behavior, sometimes called the humanistic business model , may provide the answer for businesses that wish to achieve the dual goal of human flourishing and responsible profits. In this model, organizations focus on employees as a vital part of the operation and support them in their professional training, health care, education, family responsibilities, and even spiritual concerns. Leaders create positive relationships with stakeholders, including their employees, to cultivate investor goodwill and because they believe in the underlying values of trust and authenticity. The influence of positive psychology is evident, and there is much to commend in this kinder approach to the job of management that makes an effort to establish “sustainable human welfare.” 36 However, happy employees are one thing; the human flourishing identified by Aristotle and John Stuart Mill is quite another. What, then, is missing from humanistic business? The problem is that if anything flourishes in this model, it is often the business rather than the employees. After all, free enterprise has the interests of the enterprise at heart. But employees are human beings first, which means any attempt to improve their welfare must begin by thinking of them as human beings rather than as employees. How can businesses do this? One alternative is to put the humanities into business. Businesses currently rely heavily on data analytics, algorithms, and statistical analyses to drive decision-making. The use of these tools is often backed by social science research in consumer behavior, behavioral finance, and cognitive studies. But looking to the humanities to understand business is an opportunity to engage business in subjects and ideas that have a tremendous, if often overlooked, impact on people. After all, literature that has stood the test of time can provide tremendous insight into human behavior, and Homer or Shakespeare may be more relevant to contemporary executive leadership than a business seminar on how to motivate employees. In fact, we could argue that anything that makes an impact on people should legitimately be within the scope of business. Richard DeGeorge (1933–) of the University of Kansas describes what adding the humanities to business education entails: “Students do not need psychosociological jargon in their business interactions. They do need to understand people and their motives, to know how to read and judge character, and to have the ability to imagine themselves in another’s shoes, be they those of a competitor, a boss, or a subordinate. For those dedicated to the case method, novels, short stories, and plays offer an inexhaustible storehouse of riches, more detailed, subtle, and complete than most cases written up for courses.” 37 In DeGeorge’s humanities model, business ethics would not prepare students to do certain things, for which they likely will be trained by their employers, but to be certain persons. DeGeorge suggests that “a course in the philosophy of business would enable students to think about the foundations of business—its values, ends, purpose, and justification . . . philosophy could add a critical element to business education, an element that would keep business education always alive and prevent it from becoming an accepted, orthodox ideology.” 38 Finally, if normative business ethics is to recognize and, ultimately, be based on the individual, it must address another human trait: bias. Intellectual, emotional, and social biases affect all decision-making, including those of an ethical nature. Some bias is good, as in having a favorable disposition toward those who work hard in intellectually honest ways. Bias also rewards those who support and nurture the best elements of a culture, whether corporate, social, or political. But it becomes dangerous when people use it to blind themselves to the reality around them, reinforce hardened positions even in the face of contradictory evidence, and shirk their responsibility as moral beings. An example of bias occurs when employees engage in unethical activity because it has been sanctioned by higher-ups. They abdicate personal responsibility by assigning blame elsewhere. However, no amount of rationalization of the fear of job loss, financial pressure, desire to please a supervisor, and the rest, can justify such behavior, because it diminishes moral agency , the self-awareness, freedom, and ability to make choices based on our perception of right and wrong. And such agency needs to be at the heart of business ethics. After all, we cannot make a commitment to serve customers, develop leaders, and improve life for all stakeholders unless there is freedom and moral agency, the necessary ingredients in establishing an attitude of concern, that is, respect for oneself and for others, including all appropriate stakeholders. Ethics Across Time and Cultures “What’s Love Got to Do with It?” Philosopher and historian Martin Buber (1878–1965) taught that love is not a feeling but a responsibility of one person for another. Feelings may come and go, but the solidarity that people have with each other and the care they take with one another define them as human beings ( Figure 5.8 ). Thus, love, as responsibility, depends on relationships based on good faith and concern. Business, too, is about relationships. Without a relationship of trust, there can be no exchange of goods or services upon which economies are built. Many people question the place of love in a business setting. When seen from Buber’s perspective, however, love is not an idyllic feeling but a driving force for justice and care. This does not deny the need for profit and financial success. It simply emphasizes the other side of the twofold purpose of business (profit and responsibility). In fact, John Mackey, the founder of Whole Foods, has said that love has been the basis of his success in business, which translates into care and concern for customers beyond profit and for workers beyond productivity ( Figure 5.8 ). 39 Recall the statement by IBM quoted earlier in the chapter: “[IBM] remain[s] dedicated to leading the world into a more prosperous and progressive future; to creating a world that is fairer, more diverse, more tolerant, more just.” 40 Critical Thinking Can Martin Buber’s notion of love play a role in business? What would that look like? What responsibilities do companies have regarding justice and care? Should business ethics be grounded only on more concrete tenets? Why or why not?
psychology
Summary 5.1 Sensation versus Perception Sensation occurs when sensory receptors detect sensory stimuli. Perception involves the organization, interpretation, and conscious experience of those sensations. All sensory systems have both absolute and difference thresholds, which refer to the minimum amount of stimulus energy or the minimum amount of difference in stimulus energy required to be detected about 50% of the time, respectively. Sensory adaptation, selective attention, and signal detection theory can help explain what is perceived and what is not. In addition, our perceptions are affected by a number of factors, including beliefs, values, prejudices, culture, and life experiences. 5.2 Waves and Wavelengths Both light and sound can be described in terms of wave forms with physical characteristics like amplitude, wavelength, and timbre. Wavelength and frequency are inversely related so that longer waves have lower frequencies, and shorter waves have higher frequencies. In the visual system, a light wave’s wavelength is generally associated with color, and its amplitude is associated with brightness. In the auditory system, a sound’s frequency is associated with pitch, and its amplitude is associated with loudness. 5.3 Vision Light waves cross the cornea and enter the eye at the pupil. The eye’s lens focuses this light so that the image is focused on a region of the retina known as the fovea. The fovea contains cones that possess high levels of visual acuity and operate best in bright light conditions. Rods are located throughout the retina and operate best under dim light conditions. Visual information leaves the eye via the optic nerve. Information from each visual field is sent to the opposite side of the brain at the optic chiasm. Visual information then moves through a number of brain sites before reaching the occipital lobe, where it is processed. Two theories explain color perception. The trichromatic theory asserts that three distinct cone groups are tuned to slightly different wavelengths of light, and it is the combination of activity across these cone types that results in our perception of all the colors we see. The opponent-process theory of color vision asserts that color is processed in opponent pairs and accounts for the interesting phenomenon of a negative afterimage. We perceive depth through a combination of monocular and binocular depth cues. 5.4 Hearing Sound waves are funneled into the auditory canal and cause vibrations of the eardrum; these vibrations move the ossicles. As the ossicles move, the stapes presses against the oval window of the cochlea, which causes fluid inside the cochlea to move. As a result, hair cells embedded in the basilar membrane become enlarged, which sends neural impulses to the brain via the auditory nerve. Pitch perception and sound localization are important aspects of hearing. Our ability to perceive pitch relies on both the firing rate of the hair cells in the basilar membrane as well as their location within the membrane. In terms of sound localization, both monaural and binaural cues are used to locate where sounds originate in our environment. Individuals can be born deaf, or they can develop deafness as a result of age, genetic predisposition, and/or environmental causes. Hearing loss that results from a failure of the vibration of the eardrum or the resultant movement of the ossicles is called conductive hearing loss. Hearing loss that involves a failure of the transmission of auditory nerve impulses to the brain is called sensorineural hearing loss. 5.5 The Other Senses Taste (gustation) and smell (olfaction) are chemical senses that employ receptors on the tongue and in the nose that bind directly with taste and odor molecules in order to transmit information to the brain for processing. Our ability to perceive touch, temperature, and pain is mediated by a number of receptors and free nerve endings that are distributed throughout the skin and various tissues of the body. The vestibular sense helps us maintain a sense of balance through the response of hair cells in the utricle, saccule, and semi-circular canals that respond to changes in head position and gravity. Our proprioceptive and kinesthetic systems provide information about body position and body movement through receptors that detect stretch and tension in the muscles, joints, tendons, and skin of the body. 5.6 Gestalt Principles of Perception Gestalt theorists have been incredibly influential in the areas of sensation and perception. Gestalt principles such as figure-ground relationship, grouping by proximity or similarity, the law of good continuation, and closure are all used to help explain how we organize sensory information. Our perceptions are not infallible, and they can be influenced by bias, prejudice, and other factors.
Chapter Outline 5.1 Sensation versus Perception 5.2 Waves and Wavelengths 5.3 Vision 5.4 Hearing 5.5 The Other Senses 5.6 Gestalt Principles of Perception Introduction Imagine standing on a city street corner. You might be struck by movement everywhere as cars and people go about their business, by the sound of a street musician’s melody or a horn honking in the distance, by the smell of exhaust fumes or of food being sold by a nearby vendor, and by the sensation of hard pavement under your feet. We rely on our sensory systems to provide important information about our surroundings. We use this information to successfully navigate and interact with our environment so that we can find nourishment, seek shelter, maintain social relationships, and avoid potentially dangerous situations. This chapter will provide an overview of how sensory information is received and processed by the nervous system and how that affects our conscious experience of the world. We begin by learning the distinction between sensation and perception. Then we consider the physical properties of light and sound stimuli, along with an overview of the basic structure and function of the major sensory systems. The chapter will close with a discussion of a historically important theory of perception called Gestalt.
[ { "answer": { "ans_choice": 0, "ans_text": "absolute threshold" }, "bloom": null, "hl_context": "The sensitivity of a given sensory system to the relevant stimuli can be expressed as an absolute threshold . <hl> Absolute threshold refers to the minimum amount of stimulus energy that must be present for the stimulus to be detected 50 % of the time . <hl> Another way to think about this is by asking how dim can a light be or how soft can a sound be and still be detected half of the time . The sensitivity of our sensory receptors can be quite amazing . It has been estimated that on a clear night , the most sensitive sensory cells in the back of the eye can detect a candle flame 30 miles away ( Okawa & Sampath , 2007 ) . Under quiet conditions , the hair cells ( the receptor cells of the inner ear ) can detect the tick of a clock 20 feet away ( Galanter , 1962 ) . It is also possible for us to get messages that are presented below the threshold for conscious awareness — these are called subliminal messages . A stimulus reaches a physiological threshold when it is strong enough to excite sensory receptors and send nerve impulses to the brain : This is an absolute threshold . A message below that threshold is said to be subliminal : We receive it , but we are not consciously aware of it . Over the years there has been a great deal of speculation about the use of subliminal messages in advertising , rock music , and self-help audio programs . Research evidence shows that in laboratory settings , people can process and respond to information outside of awareness . But this does not mean that we obey these messages like zombies ; in fact , hidden messages have little effect on behavior outside the laboratory ( Kunst-Wilson & Zajonc , 1980 ; Rensink , 2004 ; Nelson , 2008 ; Radel , Sarrazin , Legrain , & Gobancé , 2009 ; Loersch , Durso , & Petty , 2013 ) .", "hl_sentences": "Absolute threshold refers to the minimum amount of stimulus energy that must be present for the stimulus to be detected 50 % of the time .", "question": { "cloze_format": "________ refers to the minimum amount of stimulus energy required to be detected 50% of the time.", "normal_format": "What refers to the minimum amount of stimulus energy required to be detected 50% of the time?", "question_choices": [ "absolute threshold", "difference threshold", "just noticeable difference", "transduction" ], "question_id": "fs-idp158937488", "question_text": "________ refers to the minimum amount of stimulus energy required to be detected 50% of the time." }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 2, "ans_text": "sensory adaptation" }, "bloom": null, "hl_context": "Although our perceptions are built from sensations , not all sensations result in perception . <hl> In fact , we often don ’ t perceive stimuli that remain relatively constant over prolonged periods of time . <hl> <hl> This is known as sensory adaptation . <hl> Imagine entering a classroom with an old analog clock . Upon first entering the room , you can hear the ticking of the clock ; as you begin to engage in conversation with classmates or listen to your professor greet the class , you are no longer aware of the ticking . The clock is still ticking , and that information is still affecting sensory receptors of the auditory system . The fact that you no longer perceive the sound demonstrates sensory adaptation and shows that while closely associated , sensation and perception are different .", "hl_sentences": "In fact , we often don ’ t perceive stimuli that remain relatively constant over prolonged periods of time . This is known as sensory adaptation .", "question": { "cloze_format": "Decreased sensitivity to an unchanging stimulus is known as ________.", "normal_format": "Decreased sensitivity to an unchanging stimulus is known as what?", "question_choices": [ "transduction", "difference threshold", "sensory adaptation", "inattentional blindness" ], "question_id": "fs-idp63067264", "question_text": "Decreased sensitivity to an unchanging stimulus is known as ________." }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 3, "ans_text": "transduction" }, "bloom": null, "hl_context": "What does it mean to sense something ? Sensory receptors are specialized neurons that respond to specific types of stimuli . When sensory information is detected by a sensory receptor , sensation has occurred . For example , light that enters the eye causes chemical changes in cells that line the back of the eye . These cells relay messages , in the form of action potentials ( as you learned when studying biopsychology ) , to the central nervous system . <hl> The conversion from sensory stimulus energy to action potential is known as transduction . <hl>", "hl_sentences": "The conversion from sensory stimulus energy to action potential is known as transduction .", "question": { "cloze_format": "________ involves the conversion of sensory stimulus energy into neural impulses.", "normal_format": "Which involves the conversion of sensory stimulus energy into neural impulses?", "question_choices": [ "sensory adaptation", "inattentional blindness", "difference threshold", "transduction" ], "question_id": "fs-idp155381072", "question_text": "________ involves the conversion of sensory stimulus energy into neural impulses." }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 1, "ans_text": "perception" }, "bloom": null, "hl_context": "While our sensory receptors are constantly collecting information from the environment , it is ultimately how we interpret that information that affects how we interact with the world . <hl> Perception refers to the way sensory information is organized , interpreted , and consciously experienced . <hl> Perception involves both bottom-up and top-down processing . Bottom-up processing refers to the fact that perceptions are built from sensory input . On the other hand , how we interpret those sensations is influenced by our available knowledge , our experiences , and our thoughts . This is called top-down processing .", "hl_sentences": "Perception refers to the way sensory information is organized , interpreted , and consciously experienced .", "question": { "cloze_format": "________ occurs when sensory information is organized, interpreted, and consciously experienced.", "normal_format": "Which occurs when sensory information is organized, interpreted, and consciously experienced?", "question_choices": [ "sensation", "perception", "transduction", "sensory adaptation" ], "question_id": "fs-idp79308960", "question_text": "________ occurs when sensory information is organized, interpreted, and consciously experienced." }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 1, "ans_text": "yellow to orange to red" }, "bloom": null, "hl_context": "In humans , light wavelength is associated with perception of color ( Figure 5.7 ) . <hl> Within the visible spectrum , our experience of red is associated with longer wavelengths , greens are intermediate , and blues and violets are shorter in wavelength . <hl> <hl> ( An easy way to remember this is the mnemonic ROYGBIV : r ed , o range , y ellow , g reen , b lue , i ndigo , v iolet . ) <hl> The amplitude of light waves is associated with our experience of brightness or intensity of color , with larger amplitudes appearing brighter .", "hl_sentences": "Within the visible spectrum , our experience of red is associated with longer wavelengths , greens are intermediate , and blues and violets are shorter in wavelength . ( An easy way to remember this is the mnemonic ROYGBIV : r ed , o range , y ellow , g reen , b lue , i ndigo , v iolet . )", "question": { "cloze_format": "As we move from short wavelengths to long wavelengths, the pattern in our perception of color goes from ___.", "normal_format": "Which of the following correctly matches the pattern in our perception of color as we move from short wavelengths to long wavelengths?", "question_choices": [ "red to orange to yellow", "yellow to orange to red", "yellow to red to orange", "orange to yellow to red" ], "question_id": "fs-idp12399872", "question_text": "Which of the following correctly matches the pattern in our perception of color as we move from short wavelengths to long wavelengths?" }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 0, "ans_text": "400–700 nm" }, "bloom": null, "hl_context": "The visible spectrum is the portion of the larger electromagnetic spectrum that we can see . As Figure 5.6 shows , the electromagnetic spectrum encompasses all of the electromagnetic radiation that occurs in our environment and includes gamma rays , x-rays , ultraviolet light , visible light , infrared light , microwaves , and radio waves . <hl> The visible spectrum in humans is associated with wavelengths that range from 380 to 740 nm — a very small distance , since a nanometer ( nm ) is one billionth of a meter . <hl> Other species can detect other portions of the electromagnetic spectrum . For instance , honeybees can see light in the ultraviolet range ( Wakakuwa , Stavenga , & Arikawa , 2007 ) , and some snakes can detect infrared radiation in addition to more traditional visual light cues ( Chen , Deng , Brauth , Ding , & Tang , 2012 ; Hartline , Kass , & Loop , 1978 ) .", "hl_sentences": "The visible spectrum in humans is associated with wavelengths that range from 380 to 740 nm — a very small distance , since a nanometer ( nm ) is one billionth of a meter .", "question": { "cloze_format": "The visible spectrum includes light that ranges from about ________.", "normal_format": "The visible spectrum includes light that ranges from about what?", "question_choices": [ "400–700 nm", "200–900 nm", "20–20000 Hz", "10–20 dB" ], "question_id": "fs-idm81510256", "question_text": "The visible spectrum includes light that ranges from about ________." }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 2, "ans_text": "infrared light" }, "bloom": null, "hl_context": "The visible spectrum is the portion of the larger electromagnetic spectrum that we can see . <hl> As Figure 5.6 shows , the electromagnetic spectrum encompasses all of the electromagnetic radiation that occurs in our environment and includes gamma rays , x-rays , ultraviolet light , visible light , infrared light , microwaves , and radio waves . <hl> The visible spectrum in humans is associated with wavelengths that range from 380 to 740 nm — a very small distance , since a nanometer ( nm ) is one billionth of a meter . Other species can detect other portions of the electromagnetic spectrum . For instance , honeybees can see light in the ultraviolet range ( Wakakuwa , Stavenga , & Arikawa , 2007 ) , and some snakes can detect infrared radiation in addition to more traditional visual light cues ( Chen , Deng , Brauth , Ding , & Tang , 2012 ; Hartline , Kass , & Loop , 1978 ) .", "hl_sentences": "As Figure 5.6 shows , the electromagnetic spectrum encompasses all of the electromagnetic radiation that occurs in our environment and includes gamma rays , x-rays , ultraviolet light , visible light , infrared light , microwaves , and radio waves .", "question": { "cloze_format": "The electromagnetic spectrum includes ________.", "normal_format": "Which does the electromagnetic spectrum include?", "question_choices": [ "radio waves", "x-rays", "infrared light", "all of the above" ], "question_id": "fs-idm16357104", "question_text": "The electromagnetic spectrum includes ________." }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 3, "ans_text": "20-20,000 Hz" }, "bloom": null, "hl_context": "Like light waves , the physical properties of sound waves are associated with various aspects of our perception of sound . The frequency of a sound wave is associated with our perception of that sound ’ s pitch . High-frequency sound waves are perceived as high-pitched sounds , while low-frequency sound waves are perceived as low-pitched sounds . <hl> The audible range of sound frequencies is between 20 and 20000 Hz , with greatest sensitivity to those frequencies that fall in the middle of this range . <hl>", "hl_sentences": "The audible range of sound frequencies is between 20 and 20000 Hz , with greatest sensitivity to those frequencies that fall in the middle of this range .", "question": { "cloze_format": "The audible range for humans is ________.", "normal_format": "What is the audible range for humans?", "question_choices": [ "380–740 Hz", "10–20 dB", "less than 300 dB", "20-20,000 Hz" ], "question_id": "fs-idp14847328", "question_text": "The audible range for humans is ________." }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 3, "ans_text": "timbre" }, "bloom": null, "hl_context": "Of course , different musical instruments can play the same musical note at the same level of loudness , yet they still sound quite different . <hl> This is known as the timbre of a sound . <hl> <hl> Timbre refers to a sound ’ s purity , and it is affected by the complex interplay of frequency , amplitude , and timing of sound waves . <hl> 5.3 Vision Learning Objectives By the end of this section , you will be able to :", "hl_sentences": "This is known as the timbre of a sound . Timbre refers to a sound ’ s purity , and it is affected by the complex interplay of frequency , amplitude , and timing of sound waves .", "question": { "cloze_format": "The quality of a sound that is affected by frequency, amplitude, and timing of the sound wave is known as ________.", "normal_format": "What is the quality of a sound that is affected by frequency, amplitude, and timing of the sound wave known as?", "question_choices": [ "pitch", "tone", "electromagnetic", "timbre" ], "question_id": "fs-idm106796848", "question_text": "The quality of a sound that is affected by frequency, amplitude, and timing of the sound wave is known as ________." }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 2, "ans_text": "fovea" }, "bloom": null, "hl_context": "<hl> While cones are concentrated in the fovea , where images tend to be focused , rods , another type of photoreceptor , are located throughout the remainder of the retina . <hl> Rods are specialized photoreceptors that work well in low light conditions , and while they lack the spatial resolution and color function of the cones , they are involved in our vision in dimly lit environments as well as in our perception of movement on the periphery of our visual field . After passing through the pupil , light crosses the lens , a curved , transparent structure that serves to provide additional focus . The lens is attached to muscles that can change its shape to aid in focusing light that is reflected from near or far objects . In a normal-sighted individual , the lens will focus images perfectly on a small indentation in the back of the eye known as the fovea , which is part of the retina , the light-sensitive lining of the eye . <hl> The fovea contains densely packed specialized photoreceptor cells ( Figure 5.11 ) . <hl> <hl> These photoreceptor cells , known as cones , are light-detecting cells . <hl> The cones are specialized types of photoreceptors that work best in bright light conditions . Cones are very sensitive to acute detail and provide tremendous spatial resolution . They also are directly involved in our ability to perceive color .", "hl_sentences": "While cones are concentrated in the fovea , where images tend to be focused , rods , another type of photoreceptor , are located throughout the remainder of the retina . The fovea contains densely packed specialized photoreceptor cells ( Figure 5.11 ) . These photoreceptor cells , known as cones , are light-detecting cells .", "question": { "cloze_format": "The ________ is a small indentation of the retina that contains cones.", "normal_format": "What is a small indentation of the retina that contains cones?", "question_choices": [ "optic chiasm", "optic nerve", "fovea", "iris" ], "question_id": "fs-idm385760", "question_text": "The ________ is a small indentation of the retina that contains cones." }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 0, "ans_text": "cones" }, "bloom": null, "hl_context": "We have all experienced the different sensitivities of rods and cones when making the transition from a brightly lit environment to a dimly lit environment . Imagine going to see a blockbuster movie on a clear summer day . As you walk from the brightly lit lobby into the dark theater , you notice that you immediately have difficulty seeing much of anything . After a few minutes , you begin to adjust to the darkness and can see the interior of the theater . <hl> In the bright environment , your vision was dominated primarily by cone activity . <hl> As you move to the dark environment , rod activity dominates , but there is a delay in transitioning between the phases . If your rods do not transform light into nerve impulses as easily and efficiently as they should , you will have difficulty seeing in dim light , a condition known as night blindness . After passing through the pupil , light crosses the lens , a curved , transparent structure that serves to provide additional focus . The lens is attached to muscles that can change its shape to aid in focusing light that is reflected from near or far objects . In a normal-sighted individual , the lens will focus images perfectly on a small indentation in the back of the eye known as the fovea , which is part of the retina , the light-sensitive lining of the eye . The fovea contains densely packed specialized photoreceptor cells ( Figure 5.11 ) . These photoreceptor cells , known as cones , are light-detecting cells . <hl> The cones are specialized types of photoreceptors that work best in bright light conditions . <hl> Cones are very sensitive to acute detail and provide tremendous spatial resolution . They also are directly involved in our ability to perceive color .", "hl_sentences": "In the bright environment , your vision was dominated primarily by cone activity . The cones are specialized types of photoreceptors that work best in bright light conditions .", "question": { "cloze_format": "________ operate best under bright light conditions.", "normal_format": "Which operates best under bright light conditions?", "question_choices": [ "cones", "rods", "retinal ganglion cells", "striate cortex" ], "question_id": "fs-idm98190176", "question_text": "________ operate best under bright light conditions." }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 1, "ans_text": "binocular" }, "bloom": null, "hl_context": "Our world is three-dimensional , so it makes sense that our mental representation of the world has three-dimensional properties . We use a variety of cues in a visual scene to establish our sense of depth . <hl> Some of these are binocular cues , which means that they rely on the use of both eyes . <hl> <hl> One example of a binocular depth cue is binocular disparity , the slightly different view of the world that each of our eyes receives . <hl> To experience this slightly different view , do this simple exercise : extend your arm fully and extend one of your fingers and focus on that finger . Now , close your left eye without moving your head , then open your left eye and close your right eye without moving your head . You will notice that your finger seems to shift as you alternate between the two eyes because of the slightly different view each eye has of your finger .", "hl_sentences": "Some of these are binocular cues , which means that they rely on the use of both eyes . One example of a binocular depth cue is binocular disparity , the slightly different view of the world that each of our eyes receives .", "question": { "cloze_format": "________ depth cues require the use of both eyes.", "normal_format": "Which depth cues require the use of both eyes?", "question_choices": [ "monocular", "binocular", "linear perspective", "accommodating" ], "question_id": "fs-idm42164608", "question_text": "________ depth cues require the use of both eyes." }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 1, "ans_text": "high-frequency" }, "bloom": null, "hl_context": "The place theory of pitch perception suggests that different portions of the basilar membrane are sensitive to sounds of different frequencies . <hl> More specifically , the base of the basilar membrane responds best to high frequencies and the tip of the basilar membrane responds best to low frequencies . <hl> Therefore , hair cells that are in the base portion would be labeled as high-pitch receptors , while those in the tip of basilar membrane would be labeled as low-pitch receptors ( Shamma , 2001 ) .", "hl_sentences": "More specifically , the base of the basilar membrane responds best to high frequencies and the tip of the basilar membrane responds best to low frequencies .", "question": { "cloze_format": "Hair cells located near the base of the basilar membrane respond best to ________ sounds.", "normal_format": "Which sounds hair cells located near the base of the basilar membrane respond best? ", "question_choices": [ "low-frequency", "high-frequency", "low-amplitude", "high-amplitude" ], "question_id": "fs-idm108149248", "question_text": "Hair cells located near the base of the basilar membrane respond best to ________ sounds." }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 3, "ans_text": "both a and b" }, "bloom": null, "hl_context": "The ear can be separated into multiple sections . The outer ear includes the pinna , which is the visible part of the ear that protrudes from our heads , the auditory canal , and the tympanic membrane , or eardrum . <hl> The middle ear contains three tiny bones known as the ossicles , which are named the malleus ( or hammer ) , incus ( or anvil ) , and the stapes ( or stirrup ) . <hl> The inner ear contains the semi-circular canals , which are involved in balance and movement ( the vestibular sense ) , and the cochlea . The cochlea is a fluid-filled , snail-shaped structure that contains the sensory receptor cells ( hair cells ) of the auditory system ( Figure 5.16 ) .", "hl_sentences": "The middle ear contains three tiny bones known as the ossicles , which are named the malleus ( or hammer ) , incus ( or anvil ) , and the stapes ( or stirrup ) .", "question": { "cloze_format": "The three ossicles of the middle ear are known as ________.", "normal_format": "What are the three ossicles of the middle ear?", "question_choices": [ "malleus, incus, and stapes", "hammer, anvil, and stirrup", "pinna, cochlea, and utricle", "both a and b" ], "question_id": "fs-idm133558528", "question_text": "The three ossicles of the middle ear are known as ________." }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 2, "ans_text": "conductive hearing loss" }, "bloom": null, "hl_context": "Given the mechanical nature by which the sound wave stimulus is transmitted from the eardrum through the ossicles to the oval window of the cochlea , some degree of hearing loss is inevitable . <hl> With conductive hearing loss , hearing problems are associated with a failure in the vibration of the eardrum and / or movement of the ossicles . <hl> <hl> These problems are often dealt with through devices like hearing aids that amplify incoming sound waves to make vibration of the eardrum and movement of the ossicles more likely to occur . <hl>", "hl_sentences": "With conductive hearing loss , hearing problems are associated with a failure in the vibration of the eardrum and / or movement of the ossicles . These problems are often dealt with through devices like hearing aids that amplify incoming sound waves to make vibration of the eardrum and movement of the ossicles more likely to occur .", "question": { "cloze_format": "Hearing aids might be effective for treating ________.", "normal_format": "Hearing aids might be effective for treating what?", "question_choices": [ "Ménière's disease", "sensorineural hearing loss", "conductive hearing loss", "interaural time differences" ], "question_id": "fs-idm135222528", "question_text": "Hearing aids might be effective for treating ________." }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 3, "ans_text": "binaural" }, "bloom": null, "hl_context": "<hl> Binaural cues , on the other hand , provide information on the location of a sound along a horizontal axis by relying on differences in patterns of vibration of the eardrum between our two ears . <hl> If a sound comes from an off-center location , it creates two types of binaural cues : interaural level differences and interaural timing differences . Interaural level difference refers to the fact that a sound coming from the right side of your body is more intense at your right ear than at your left ear because of the attenuation of the sound wave as it passes through your head . Interaural timing difference refers to the small difference in the time at which a given sound wave arrives at each ear ( Figure 5.17 ) . Certain brain areas monitor these differences to construct where along a horizontal axis a sound originates ( Grothe et al . , 2010 ) .", "hl_sentences": "Binaural cues , on the other hand , provide information on the location of a sound along a horizontal axis by relying on differences in patterns of vibration of the eardrum between our two ears .", "question": { "cloze_format": "Cues that require two ears are referred to as ________ cues.", "normal_format": "What are cues that require two ears referred to?", "question_choices": [ "monocular", "monaural", "binocular", "binaural" ], "question_id": "fs-idm126329248", "question_text": "Cues that require two ears are referred to as ________ cues." }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 1, "ans_text": "pheromones" }, "bloom": null, "hl_context": "<hl> Many species respond to chemical messages , known as pheromones , sent by another individual ( Wysocki & Preti , 2004 ) . <hl> <hl> Pheromonal communication often involves providing information about the reproductive status of a potential mate . <hl> So , for example , when a female rat is ready to mate , she secretes pheromonal signals that draw attention from nearby male rats . Pheromonal activation is actually an important component in eliciting sexual behavior in the male rat ( Furlow , 1996 , 2012 ; Purvis & Haynes , 1972 ; Sachs , 1997 ) . There has also been a good deal of research ( and controversy ) about pheromones in humans ( Comfort , 1971 ; Russell , 1976 ; Wolfgang-Kimball , 1992 ; Weller , 1998 ) .", "hl_sentences": "Many species respond to chemical messages , known as pheromones , sent by another individual ( Wysocki & Preti , 2004 ) . Pheromonal communication often involves providing information about the reproductive status of a potential mate .", "question": { "cloze_format": "Chemical messages often sent between two members of a species to communicate something about reproductive status are called ________.", "normal_format": "What were chemical messages often sent between two members of a species to communicate something about reproductive status called?", "question_choices": [ "hormones", "pheromones", "Merkel’s disks", "Meissner’s corpuscles" ], "question_id": "fs-idm21242624", "question_text": "Chemical messages often sent between two members of a species to communicate something about reproductive status are called ________." }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 2, "ans_text": "umami" }, "bloom": null, "hl_context": "You have learned since elementary school that there are four basic groupings of taste : sweet , salty , sour , and bitter . Research demonstrates , however , that we have at least six taste groupings . Umami is our fifth taste . <hl> Umami is actually a Japanese word that roughly translates to yummy , and it is associated with a taste for monosodium glutamate ( Kinnamon & Vandenbeuch , 2009 ) . <hl> There is also a growing body of experimental evidence suggesting that we possess a taste for the fatty content of a given food ( Mizushige , Inoue , & Fushiki , 2007 ) .", "hl_sentences": "Umami is actually a Japanese word that roughly translates to yummy , and it is associated with a taste for monosodium glutamate ( Kinnamon & Vandenbeuch , 2009 ) .", "question": { "cloze_format": "___ is associated with monosodium glutamate.", "normal_format": "Which taste is associated with monosodium glutamate?", "question_choices": [ "sweet", "bitter", "umami", "sour" ], "question_id": "fs-idp80464880", "question_text": "Which taste is associated with monosodium glutamate?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 0, "ans_text": "free nerve endings" }, "bloom": null, "hl_context": "<hl> In addition to the receptors located in the skin , there are also a number of free nerve endings that serve sensory functions . <hl> <hl> These nerve endings respond to a variety of different types of touch-related stimuli and serve as sensory receptors for both thermoception ( temperature perception ) and nociception ( a signal indicating potential harm and maybe pain ) ( Garland , 2012 ; Petho & Reeh , 2012 ; Spray , 1986 ) . <hl> Sensory information collected from the receptors and free nerve endings travels up the spinal cord and is transmitted to regions of the medulla , thalamus , and ultimately to somatosensory cortex , which is located in the postcentral gyrus of the parietal lobe .", "hl_sentences": "In addition to the receptors located in the skin , there are also a number of free nerve endings that serve sensory functions . These nerve endings respond to a variety of different types of touch-related stimuli and serve as sensory receptors for both thermoception ( temperature perception ) and nociception ( a signal indicating potential harm and maybe pain ) ( Garland , 2012 ; Petho & Reeh , 2012 ; Spray , 1986 ) .", "question": { "cloze_format": "________ serve as sensory receptors for temperature and pain stimuli.", "normal_format": "Which serve as sensory receptors for temperature and pain stimuli?", "question_choices": [ "free nerve endings", "Pacinian corpuscles", "Ruffini corpuscles", "Meissner’s corpuscles" ], "question_id": "fs-idp110065696", "question_text": "________ serve as sensory receptors for temperature and pain stimuli." }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 3, "ans_text": "vestibular system" }, "bloom": null, "hl_context": "<hl> In addition to maintaining balance , the vestibular system collects information critical for controlling movement and the reflexes that move various parts of our bodies to compensate for changes in body position . <hl> Therefore , both proprioception ( perception of body position ) and kinesthesia ( perception of the body ’ s movement through space ) interact with information provided by the vestibular system . <hl> The vestibular sense contributes to our ability to maintain balance and body posture . <hl> As Figure 5.22 shows , the major sensory organs ( utricle , saccule , and the three semicircular canals ) of this system are located next to the cochlea in the inner ear . The vestibular organs are fluid-filled and have hair cells , similar to the ones found in the auditory system , which respond to movement of the head and gravitational forces . When these hair cells are stimulated , they send signals to the brain via the vestibular nerve . Although we may not be consciously aware of our vestibular system ’ s sensory information under normal circumstances , its importance is apparent when we experience motion sickness and / or dizziness related to infections of the inner ear ( Khan & Chang , 2013 ) .", "hl_sentences": "In addition to maintaining balance , the vestibular system collects information critical for controlling movement and the reflexes that move various parts of our bodies to compensate for changes in body position . The vestibular sense contributes to our ability to maintain balance and body posture .", "question": { "cloze_format": "The ___ is involved in maintaining balance and body posture.", "normal_format": "Which of the following is involved in maintaining balance and body posture?", "question_choices": [ "auditory nerve", "nociceptors", "olfactory bulb", "vestibular system" ], "question_id": "fs-idm13249056", "question_text": "Which of the following is involved in maintaining balance and body posture?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 2, "ans_text": "proximity" }, "bloom": null, "hl_context": "<hl> Another Gestalt principle for organizing sensory stimuli into meaningful perception is proximity . <hl> <hl> This principle asserts that things that are close to one another tend to be grouped together , as Figure 5.24 illustrates . <hl>", "hl_sentences": "Another Gestalt principle for organizing sensory stimuli into meaningful perception is proximity . This principle asserts that things that are close to one another tend to be grouped together , as Figure 5.24 illustrates .", "question": { "cloze_format": "According to the principle of ________, objects that occur close to one another tend to be grouped together.", "normal_format": "According to which principle do objects that occur close to one another tend to be grouped together?", "question_choices": [ "similarity", "good continuation", "proximity", "closure" ], "question_id": "fs-idm10330304", "question_text": "According to the principle of ________, objects that occur close to one another tend to be grouped together." }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 0, "ans_text": "closure" }, "bloom": null, "hl_context": "Two additional Gestalt principles are the law of continuity ( or good continuation ) and closure . The law of continuity suggests that we are more likely to perceive continuous , smooth flowing lines rather than jagged , broken lines ( Figure 5.26 ) . <hl> The principle of closure states that we organize our perceptions into complete objects rather than as a series of parts ( Figure 5.27 ) . <hl>", "hl_sentences": "The principle of closure states that we organize our perceptions into complete objects rather than as a series of parts ( Figure 5.27 ) .", "question": { "cloze_format": "Our tendency to perceive things as complete objects rather than as a series of parts is known as the principle of ________.", "normal_format": "Our tendency to perceive things as complete objects rather than as a series of parts is known as which principle?", "question_choices": [ "closure", "good continuation", "proximity", "similarity" ], "question_id": "fs-idm10220304", "question_text": "Our tendency to perceive things as complete objects rather than as a series of parts is known as the principle of ________." }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 1, "ans_text": "good continuation" }, "bloom": null, "hl_context": "Two additional Gestalt principles are the law of continuity ( or good continuation ) and closure . <hl> The law of continuity suggests that we are more likely to perceive continuous , smooth flowing lines rather than jagged , broken lines ( Figure 5.26 ) . <hl> The principle of closure states that we organize our perceptions into complete objects rather than as a series of parts ( Figure 5.27 ) .", "hl_sentences": "The law of continuity suggests that we are more likely to perceive continuous , smooth flowing lines rather than jagged , broken lines ( Figure 5.26 ) .", "question": { "cloze_format": "According to the law of ________, we are more likely to perceive smoothly flowing lines rather than choppy or jagged lines.", "normal_format": "According to which law, are we more likely to perceive smoothly flowing lines rather than choppy or jagged lines?", "question_choices": [ "closure", "good continuation", "proximity", "similarity" ], "question_id": "fs-idm10121204", "question_text": "According to the law of ________, we are more likely to perceive smoothly flowing lines rather than choppy or jagged lines." }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 3, "ans_text": "figure" }, "bloom": null, "hl_context": "One Gestalt principle is the figure-ground relationship . According to this principle , we tend to segment our visual world into figure and ground . <hl> Figure is the object or person that is the focus of the visual field , while the ground is the background . <hl> As Figure 5.23 shows , our perception can vary tremendously , depending on what is perceived as figure and what is perceived as ground . Presumably , our ability to interpret sensory information depends on what we label as figure and what we label as ground in any particular case , although this assumption has been called into question ( Peterson & Gibson , 1994 ; Vecera & O ’ Reilly , 1998 ) .", "hl_sentences": "Figure is the object or person that is the focus of the visual field , while the ground is the background .", "question": { "cloze_format": "The main point of focus in a visual display is known as the ________.", "normal_format": "What is the main point of focus in a visual display known as?", "question_choices": [ "closure", "perceptual set", "ground", "figure" ], "question_id": "fs-idm44658320", "question_text": "The main point of focus in a visual display is known as the ________." }, "references_are_paraphrase": null } ]
5
5.1 Sensation versus Perception Learning Objectives By the end of this section, you will be able to: Distinguish between sensation and perception Describe the concepts of absolute threshold and difference threshold Discuss the roles attention, motivation, and sensory adaptation play in perception Sensation What does it mean to sense something? Sensory receptors are specialized neurons that respond to specific types of stimuli. When sensory information is detected by a sensory receptor, sensation has occurred. For example, light that enters the eye causes chemical changes in cells that line the back of the eye. These cells relay messages, in the form of action potentials (as you learned when studying biopsychology), to the central nervous system. The conversion from sensory stimulus energy to action potential is known as transduction . You have probably known since elementary school that we have five senses: vision, hearing (audition), smell (olfaction), taste (gustation), and touch (somatosensation). It turns out that this notion of five senses is oversimplified. We also have sensory systems that provide information about balance (the vestibular sense), body position and movement (proprioception and kinesthesia), pain (nociception), and temperature (thermoception). The sensitivity of a given sensory system to the relevant stimuli can be expressed as an absolute threshold. Absolute threshold refers to the minimum amount of stimulus energy that must be present for the stimulus to be detected 50% of the time. Another way to think about this is by asking how dim can a light be or how soft can a sound be and still be detected half of the time. The sensitivity of our sensory receptors can be quite amazing. It has been estimated that on a clear night, the most sensitive sensory cells in the back of the eye can detect a candle flame 30 miles away (Okawa & Sampath, 2007). Under quiet conditions, the hair cells (the receptor cells of the inner ear) can detect the tick of a clock 20 feet away (Galanter, 1962). It is also possible for us to get messages that are presented below the threshold for conscious awareness—these are called subliminal messages . A stimulus reaches a physiological threshold when it is strong enough to excite sensory receptors and send nerve impulses to the brain: This is an absolute threshold. A message below that threshold is said to be subliminal: We receive it, but we are not consciously aware of it. Over the years there has been a great deal of speculation about the use of subliminal messages in advertising, rock music, and self-help audio programs. Research evidence shows that in laboratory settings, people can process and respond to information outside of awareness. But this does not mean that we obey these messages like zombies; in fact, hidden messages have little effect on behavior outside the laboratory (Kunst-Wilson & Zajonc, 1980; Rensink, 2004; Nelson, 2008; Radel, Sarrazin, Legrain, & Gobancé, 2009; Loersch, Durso, & Petty, 2013). Absolute thresholds are generally measured under incredibly controlled conditions in situations that are optimal for sensitivity. Sometimes, we are more interested in how much difference in stimuli is required to detect a difference between them. This is known as the just noticeable difference (jnd) or difference threshold . Unlike the absolute threshold, the difference threshold changes depending on the stimulus intensity. As an example, imagine yourself in a very dark movie theater. If an audience member were to receive a text message on her cell phone which caused her screen to light up, chances are that many people would notice the change in illumination in the theater. However, if the same thing happened in a brightly lit arena during a basketball game, very few people would notice. The cell phone brightness does not change, but its ability to be detected as a change in illumination varies dramatically between the two contexts. Ernst Weber proposed this theory of change in difference threshold in the 1830s, and it has become known as Weber’s law: The difference threshold is a constant fraction of the original stimulus, as the example illustrates. Perception While our sensory receptors are constantly collecting information from the environment, it is ultimately how we interpret that information that affects how we interact with the world. Perception refers to the way sensory information is organized, interpreted, and consciously experienced. Perception involves both bottom-up and top-down processing. Bottom-up processing refers to the fact that perceptions are built from sensory input. On the other hand, how we interpret those sensations is influenced by our available knowledge, our experiences, and our thoughts. This is called top-down processing . One way to think of this concept is that sensation is a physical process, whereas perception is psychological. For example, upon walking into a kitchen and smelling the scent of baking cinnamon rolls, the sensation is the scent receptors detecting the odor of cinnamon, but the perception may be “Mmm, this smells like the bread Grandma used to bake when the family gathered for holidays.” Although our perceptions are built from sensations, not all sensations result in perception. In fact, we often don’t perceive stimuli that remain relatively constant over prolonged periods of time. This is known as sensory adaptation . Imagine entering a classroom with an old analog clock. Upon first entering the room, you can hear the ticking of the clock; as you begin to engage in conversation with classmates or listen to your professor greet the class, you are no longer aware of the ticking. The clock is still ticking, and that information is still affecting sensory receptors of the auditory system. The fact that you no longer perceive the sound demonstrates sensory adaptation and shows that while closely associated, sensation and perception are different. There is another factor that affects sensation and perception: attention. Attention plays a significant role in determining what is sensed versus what is perceived. Imagine you are at a party full of music, chatter, and laughter. You get involved in an interesting conversation with a friend, and you tune out all the background noise. If someone interrupted you to ask what song had just finished playing, you would probably be unable to answer that question. Link to Learning See for yourself how inattentional blindness works by checking out this selective attention test from Simons and Chabris (1999). One of the most interesting demonstrations of how important attention is in determining our perception of the environment occurred in a famous study conducted by Daniel Simons and Christopher Chabris (1999). In this study, participants watched a video of people dressed in black and white passing basketballs. Participants were asked to count the number of times the team in white passed the ball. During the video, a person dressed in a black gorilla costume walks among the two teams. You would think that someone would notice the gorilla, right? Nearly half of the people who watched the video didn’t notice the gorilla at all, despite the fact that he was clearly visible for nine seconds. Because participants were so focused on the number of times the white team was passing the ball, they completely tuned out other visual information. Failure to notice something that is completely visible because of a lack of attention is called inattentional blindness . In a similar experiment, researchers tested inattentional blindness by asking participants to observe images moving across a computer screen. They were instructed to focus on either white or black objects, disregarding the other color. When a red cross passed across the screen, about one third of subjects did not notice it ( Figure 5.2 ) (Most, Simons, Scholl, & Chabris, 2000). Motivation can also affect perception. Have you ever been expecting a really important phone call and, while taking a shower, you think you hear the phone ringing, only to discover that it is not? If so, then you have experienced how motivation to detect a meaningful stimulus can shift our ability to discriminate between a true sensory stimulus and background noise. The ability to identify a stimulus when it is embedded in a distracting background is called signal detection theory . This might also explain why a mother is awakened by a quiet murmur from her baby but not by other sounds that occur while she is asleep. Signal detection theory has practical applications, such as increasing air traffic controller accuracy. Controllers need to be able to detect planes among many signals (blips) that appear on the radar screen and follow those planes as they move through the sky. In fact, the original work of the researcher who developed signal detection theory was focused on improving the sensitivity of air traffic controllers to plane blips (Swets, 1964). Our perceptions can also be affected by our beliefs, values, prejudices, expectations, and life experiences. As you will see later in this chapter, individuals who are deprived of the experience of binocular vision during critical periods of development have trouble perceiving depth (Fawcett, Wang, & Birch, 2005). The shared experiences of people within a given cultural context can have pronounced effects on perception. For example, Marshall Segall, Donald Campbell, and Melville Herskovits (1963) published the results of a multinational study in which they demonstrated that individuals from Western cultures were more prone to experience certain types of visual illusions than individuals from non-Western cultures, and vice versa. One such illusion that Westerners were more likely to experience was the Müller-Lyer illusion ( Figure 5.3 ): The lines appear to be different lengths, but they are actually the same length. These perceptual differences were consistent with differences in the types of environmental features experienced on a regular basis by people in a given cultural context. People in Western cultures, for example, have a perceptual context of buildings with straight lines, what Segall’s study called a carpentered world (Segall et al., 1966). In contrast, people from certain non-Western cultures with an uncarpentered view, such as the Zulu of South Africa, whose villages are made up of round huts arranged in circles, are less susceptible to this illusion (Segall et al., 1999). It is not just vision that is affected by cultural factors. Indeed, research has demonstrated that the ability to identify an odor, and rate its pleasantness and its intensity, varies cross-culturally (Ayabe-Kanamura, Saito, Distel, Martínez-Gómez, & Hudson, 1998). Children described as thrill seekers are more likely to show taste preferences for intense sour flavors (Liem, Westerbeek, Wolterink, Kok, & de Graaf, 2004), which suggests that basic aspects of personality might affect perception. Furthermore, individuals who hold positive attitudes toward reduced-fat foods are more likely to rate foods labeled as reduced fat as tasting better than people who have less positive attitudes about these products (Aaron, Mela, & Evans, 1994). 5.2 Waves and Wavelengths Learning Objectives By the end of this section, you will be able to: Describe important physical features of wave forms Show how physical properties of light waves are associated with perceptual experience Show how physical properties of sound waves are associated with perceptual experience Visual and auditory stimuli both occur in the form of waves. Although the two stimuli are very different in terms of composition, wave forms share similar characteristics that are especially important to our visual and auditory perceptions. In this section, we describe the physical properties of the waves as well as the perceptual experiences associated with them. Amplitude and Wavelength Two physical characteristics of a wave are amplitude and wavelength ( Figure 5.4 ). The amplitude of a wave is the distance from the center line to the top point of the crest or the bottom point of the trough. Wavelength refers to the length of a wave from one peak to the next. Wavelength is directly related to the frequency of a given wave form. Frequency refers to the number of waves that pass a given point in a given time period and is often expressed in terms of hertz (Hz) , or cycles per second. Longer wavelengths will have lower frequencies, and shorter wavelengths will have higher frequencies ( Figure 5.5 ). Light Waves The visible spectrum is the portion of the larger electromagnetic spectrum that we can see. As Figure 5.6 shows, the electromagnetic spectrum encompasses all of the electromagnetic radiation that occurs in our environment and includes gamma rays, x-rays, ultraviolet light, visible light, infrared light, microwaves, and radio waves. The visible spectrum in humans is associated with wavelengths that range from 380 to 740 nm—a very small distance, since a nanometer (nm) is one billionth of a meter. Other species can detect other portions of the electromagnetic spectrum. For instance, honeybees can see light in the ultraviolet range (Wakakuwa, Stavenga, & Arikawa, 2007), and some snakes can detect infrared radiation in addition to more traditional visual light cues (Chen, Deng, Brauth, Ding, & Tang, 2012; Hartline, Kass, & Loop, 1978). In humans, light wavelength is associated with perception of color ( Figure 5.7 ). Within the visible spectrum, our experience of red is associated with longer wavelengths, greens are intermediate, and blues and violets are shorter in wavelength. (An easy way to remember this is the mnemonic ROYGBIV: r ed, o range, y ellow, g reen, b lue, i ndigo, v iolet.) The amplitude of light waves is associated with our experience of brightness or intensity of color, with larger amplitudes appearing brighter. Sound Waves Like light waves, the physical properties of sound waves are associated with various aspects of our perception of sound. The frequency of a sound wave is associated with our perception of that sound’s pitch . High-frequency sound waves are perceived as high-pitched sounds, while low-frequency sound waves are perceived as low-pitched sounds. The audible range of sound frequencies is between 20 and 20000 Hz, with greatest sensitivity to those frequencies that fall in the middle of this range. As was the case with the visible spectrum, other species show differences in their audible ranges. For instance, chickens have a very limited audible range, from 125 to 2000 Hz. Mice have an audible range from 1000 to 91000 Hz, and the beluga whale’s audible range is from 1000 to 123000 Hz. Our pet dogs and cats have audible ranges of about 70–45000 Hz and 45–64000 Hz, respectively (Strain, 2003). The loudness of a given sound is closely associated with the amplitude of the sound wave. Higher amplitudes are associated with louder sounds. Loudness is measured in terms of decibels (dB) , a logarithmic unit of sound intensity. A typical conversation would correlate with 60 dB; a rock concert might check in at 120 dB ( Figure 5.8 ). A whisper 5 feet away or rustling leaves are at the low end of our hearing range; sounds like a window air conditioner, a normal conversation, and even heavy traffic or a vacuum cleaner are within a tolerable range. However, there is the potential for hearing damage from about 80 dB to 130 dB: These are sounds of a food processor, power lawnmower, heavy truck (25 feet away), subway train (20 feet away), live rock music, and a jackhammer. The threshold for pain is about 130 dB, a jet plane taking off or a revolver firing at close range (Dunkle, 1982). Although wave amplitude is generally associated with loudness, there is some interaction between frequency and amplitude in our perception of loudness within the audible range. For example, a 10 Hz sound wave is inaudible no matter the amplitude of the wave. A 1000 Hz sound wave, on the other hand, would vary dramatically in terms of perceived loudness as the amplitude of the wave increased. Link to Learning Watch this brief video demonstrating how frequency and amplitude interact in our perception of loudness. Of course, different musical instruments can play the same musical note at the same level of loudness, yet they still sound quite different. This is known as the timbre of a sound. Timbre refers to a sound’s purity, and it is affected by the complex interplay of frequency, amplitude, and timing of sound waves. 5.3 Vision Learning Objectives By the end of this section, you will be able to: Describe the basic anatomy of the visual system Discuss how rods and cones contribute to different aspects of vision Describe how monocular and binocular cues are used in the perception of depth The visual system constructs a mental representation of the world around us ( Figure 5.9 ). This contributes to our ability to successfully navigate through physical space and interact with important individuals and objects in our environments. This section will provide an overview of the basic anatomy and function of the visual system. In addition, we will explore our ability to perceive color and depth. Anatomy of the Visual System The eye is the major sensory organ involved in vision ( Figure 5.10 ). Light waves are transmitted across the cornea and enter the eye through the pupil. The cornea is the transparent covering over the eye. It serves as a barrier between the inner eye and the outside world, and it is involved in focusing light waves that enter the eye. The pupil is the small opening in the eye through which light passes, and the size of the pupil can change as a function of light levels as well as emotional arousal. When light levels are low, the pupil will become dilated, or expanded, to allow more light to enter the eye. When light levels are high, the pupil will constrict, or become smaller, to reduce the amount of light that enters the eye. The pupil’s size is controlled by muscles that are connected to the iris , which is the colored portion of the eye. After passing through the pupil, light crosses the lens , a curved, transparent structure that serves to provide additional focus. The lens is attached to muscles that can change its shape to aid in focusing light that is reflected from near or far objects. In a normal-sighted individual, the lens will focus images perfectly on a small indentation in the back of the eye known as the fovea , which is part of the retina , the light-sensitive lining of the eye. The fovea contains densely packed specialized photoreceptor cells ( Figure 5.11 ). These photoreceptor cells, known as cones, are light-detecting cells. The cones are specialized types of photoreceptors that work best in bright light conditions. Cones are very sensitive to acute detail and provide tremendous spatial resolution. They also are directly involved in our ability to perceive color. While cones are concentrated in the fovea, where images tend to be focused, rods, another type of photoreceptor, are located throughout the remainder of the retina. Rods are specialized photoreceptors that work well in low light conditions, and while they lack the spatial resolution and color function of the cones, they are involved in our vision in dimly lit environments as well as in our perception of movement on the periphery of our visual field. We have all experienced the different sensitivities of rods and cones when making the transition from a brightly lit environment to a dimly lit environment. Imagine going to see a blockbuster movie on a clear summer day. As you walk from the brightly lit lobby into the dark theater, you notice that you immediately have difficulty seeing much of anything. After a few minutes, you begin to adjust to the darkness and can see the interior of the theater. In the bright environment, your vision was dominated primarily by cone activity. As you move to the dark environment, rod activity dominates, but there is a delay in transitioning between the phases. If your rods do not transform light into nerve impulses as easily and efficiently as they should, you will have difficulty seeing in dim light, a condition known as night blindness. Rods and cones are connected (via several interneurons) to retinal ganglion cells. Axons from the retinal ganglion cells converge and exit through the back of the eye to form the optic nerve . The optic nerve carries visual information from the retina to the brain. There is a point in the visual field called the blind spot : Even when light from a small object is focused on the blind spot, we do not see it. We are not consciously aware of our blind spots for two reasons: First, each eye gets a slightly different view of the visual field; therefore, the blind spots do not overlap. Second, our visual system fills in the blind spot so that although we cannot respond to visual information that occurs in that portion of the visual field, we are also not aware that information is missing. The optic nerve from each eye merges just below the brain at a point called the optic chiasm . As Figure 5.12 shows, the optic chiasm is an X-shaped structure that sits just below the cerebral cortex at the front of the brain. At the point of the optic chiasm, information from the right visual field (which comes from both eyes) is sent to the left side of the brain, and information from the left visual field is sent to the right side of the brain. Once inside the brain, visual information is sent via a number of structures to the occipital lobe at the back of the brain for processing. Visual information might be processed in parallel pathways which can generally be described as the “what pathway” and the “where/how” pathway. The “what pathway” is involved in object recognition and identification, while the “where/how pathway” is involved with location in space and how one might interact with a particular visual stimulus (Milner & Goodale, 2008; Ungerleider & Haxby, 1994). For example, when you see a ball rolling down the street, the “what pathway” identifies what the object is, and the “where/how pathway” identifies its location or movement in space. Color and Depth Perception We do not see the world in black and white; neither do we see it as two-dimensional (2-D) or flat (just height and width, no depth). Let’s look at how color vision works and how we perceive three dimensions (height, width, and depth). Color Vision Normal-sighted individuals have three different types of cones that mediate color vision . Each of these cone types is maximally sensitive to a slightly different wavelength of light. According to the trichromatic theory of color vision , shown in Figure 5.13 , all colors in the spectrum can be produced by combining red, green, and blue. The three types of cones are each receptive to one of the colors. The trichromatic theory of color vision is not the only theory—another major theory of color vision is known as the opponent-process theory . According to this theory, color is coded in opponent pairs: black-white, yellow-blue, and green-red. The basic idea is that some cells of the visual system are excited by one of the opponent colors and inhibited by the other. So, a cell that was excited by wavelengths associated with green would be inhibited by wavelengths associated with red, and vice versa. One of the implications of opponent processing is that we do not experience greenish-reds or yellowish-blues as colors. Another implication is that this leads to the experience of negative afterimages. An afterimage describes the continuation of a visual sensation after removal of the stimulus. For example, when you stare briefly at the sun and then look away from it, you may still perceive a spot of light although the stimulus (the sun) has been removed. When color is involved in the stimulus, the color pairings identified in the opponent-process theory lead to a negative afterimage. You can test this concept using the flag in Figure 5.14 . But these two theories—the trichromatic theory of color vision and the opponent-process theory—are not mutually exclusive. Research has shown that they just apply to different levels of the nervous system. For visual processing on the retina, trichromatic theory applies: the cones are responsive to three different wavelengths that represent red, blue, and green. But once the signal moves past the retina on its way to the brain, the cells respond in a way consistent with opponent-process theory (Land, 1959; Kaiser, 1997). Link to Learning Watch this video to learn about color vision in more detail. Depth Perception Our ability to perceive spatial relationships in three-dimensional (3-D) space is known as depth perception . With depth perception, we can describe things as being in front, behind, above, below, or to the side of other things. Our world is three-dimensional, so it makes sense that our mental representation of the world has three-dimensional properties. We use a variety of cues in a visual scene to establish our sense of depth. Some of these are binocular cues , which means that they rely on the use of both eyes. One example of a binocular depth cue is binocular disparity , the slightly different view of the world that each of our eyes receives. To experience this slightly different view, do this simple exercise: extend your arm fully and extend one of your fingers and focus on that finger. Now, close your left eye without moving your head, then open your left eye and close your right eye without moving your head. You will notice that your finger seems to shift as you alternate between the two eyes because of the slightly different view each eye has of your finger. A 3-D movie works on the same principle: the special glasses you wear allow the two slightly different images projected onto the screen to be seen separately by your left and your right eye. As your brain processes these images, you have the illusion that the leaping animal or running person is coming right toward you. Although we rely on binocular cues to experience depth in our 3-D world, we can also perceive depth in 2-D arrays. Think about all the paintings and photographs you have seen. Generally, you pick up on depth in these images even though the visual stimulus is 2-D. When we do this, we are relying on a number of monocular cues , or cues that require only one eye. If you think you can’t see depth with one eye, note that you don’t bump into things when using only one eye while walking—and, in fact, we have more monocular cues than binocular cues. An example of a monocular cue would be what is known as linear perspective. Linear perspective refers to the fact that we perceive depth when we see two parallel lines that seem to converge in an image ( Figure 5.15 ). Some other monocular depth cues are interposition, the partial overlap of objects, and the relative size and closeness of images to the horizon. Dig Deeper Stereoblindness Bruce Bridgeman was born with an extreme case of lazy eye that resulted in him being stereoblind, or unable to respond to binocular cues of depth. He relied heavily on monocular depth cues, but he never had a true appreciation of the 3-D nature of the world around him. This all changed one night in 2012 while Bruce was seeing a movie with his wife. The movie the couple was going to see was shot in 3-D, and even though he thought it was a waste of money, Bruce paid for the 3-D glasses when he purchased his ticket. As soon as the film began, Bruce put on the glasses and experienced something completely new. For the first time in his life he appreciated the true depth of the world around him. Remarkably, his ability to perceive depth persisted outside of the movie theater. There are cells in the nervous system that respond to binocular depth cues. Normally, these cells require activation during early development in order to persist, so experts familiar with Bruce’s case (and others like his) assume that at some point in his development, Bruce must have experienced at least a fleeting moment of binocular vision. It was enough to ensure the survival of the cells in the visual system tuned to binocular cues. The mystery now is why it took Bruce nearly 70 years to have these cells activated (Peck, 2012). 5.4 Hearing Learning Objectives By the end of this section, you will be able to: Describe the basic anatomy and function of the auditory system Explain how we encode and perceive pitch Discuss how we localize sound Our auditory system converts pressure waves into meaningful sounds. This translates into our ability to hear the sounds of nature, to appreciate the beauty of music, and to communicate with one another through spoken language. This section will provide an overview of the basic anatomy and function of the auditory system. It will include a discussion of how the sensory stimulus is translated into neural impulses, where in the brain that information is processed, how we perceive pitch, and how we know where sound is coming from. Anatomy of the Auditory System The ear can be separated into multiple sections. The outer ear includes the pinna , which is the visible part of the ear that protrudes from our heads, the auditory canal, and the tympanic membrane , or eardrum. The middle ear contains three tiny bones known as the ossicles , which are named the malleus (or hammer), incus (or anvil), and the stapes (or stirrup). The inner ear contains the semi-circular canals, which are involved in balance and movement (the vestibular sense), and the cochlea. The cochlea is a fluid-filled, snail-shaped structure that contains the sensory receptor cells (hair cells) of the auditory system ( Figure 5.16 ). Sound waves travel along the auditory canal and strike the tympanic membrane, causing it to vibrate. This vibration results in movement of the three ossicles. As the ossicles move, the stapes presses into a thin membrane of the cochlea known as the oval window. As the stapes presses into the oval window, the fluid inside the cochlea begins to move, which in turn stimulates hair cells , which are auditory receptor cells of the inner ear embedded in the basilar membrane. The basilar membrane is a thin strip of tissue within the cochlea. The activation of hair cells is a mechanical process: the stimulation of the hair cell ultimately leads to activation of the cell. As hair cells become activated, they generate neural impulses that travel along the auditory nerve to the brain. Auditory information is shuttled to the inferior colliculus, the medial geniculate nucleus of the thalamus, and finally to the auditory cortex in the temporal lobe of the brain for processing. Like the visual system, there is also evidence suggesting that information about auditory recognition and localization is processed in parallel streams (Rauschecker & Tian, 2000; Renier et al., 2009). Pitch Perception Different frequencies of sound waves are associated with differences in our perception of the pitch of those sounds. Low-frequency sounds are lower pitched, and high-frequency sounds are higher pitched. How does the auditory system differentiate among various pitches? Several theories have been proposed to account for pitch perception. We’ll discuss two of them here: temporal theory and place theory. The temporal theory of pitch perception asserts that frequency is coded by the activity level of a sensory neuron. This would mean that a given hair cell would fire action potentials related to the frequency of the sound wave. While this is a very intuitive explanation, we detect such a broad range of frequencies (20–20,000 Hz) that the frequency of action potentials fired by hair cells cannot account for the entire range. Because of properties related to sodium channels on the neuronal membrane that are involved in action potentials, there is a point at which a cell cannot fire any faster (Shamma, 2001). The place theory of pitch perception suggests that different portions of the basilar membrane are sensitive to sounds of different frequencies. More specifically, the base of the basilar membrane responds best to high frequencies and the tip of the basilar membrane responds best to low frequencies. Therefore, hair cells that are in the base portion would be labeled as high-pitch receptors, while those in the tip of basilar membrane would be labeled as low-pitch receptors (Shamma, 2001). In reality, both theories explain different aspects of pitch perception. At frequencies up to about 4000 Hz, it is clear that both the rate of action potentials and place contribute to our perception of pitch. However, much higher frequency sounds can only be encoded using place cues (Shamma, 2001). Sound Localization The ability to locate sound in our environments is an important part of hearing . Localizing sound could be considered similar to the way that we perceive depth in our visual fields. Like the monocular and binocular cues that provided information about depth, the auditory system uses both monaural (one-eared) and binaural (two-eared) cues to localize sound. Each pinna interacts with incoming sound waves differently, depending on the sound’s source relative to our bodies. This interaction provides a monaural cue that is helpful in locating sounds that occur above or below and in front or behind us. The sound waves received by your two ears from sounds that come from directly above, below, in front, or behind you would be identical; therefore, monaural cues are essential (Grothe, Pecka, & McAlpine, 2010). Binaural cues, on the other hand, provide information on the location of a sound along a horizontal axis by relying on differences in patterns of vibration of the eardrum between our two ears. If a sound comes from an off-center location, it creates two types of binaural cues: interaural level differences and interaural timing differences. Interaural level difference refers to the fact that a sound coming from the right side of your body is more intense at your right ear than at your left ear because of the attenuation of the sound wave as it passes through your head. Interaural timing difference refers to the small difference in the time at which a given sound wave arrives at each ear ( Figure 5.17 ). Certain brain areas monitor these differences to construct where along a horizontal axis a sound originates (Grothe et al., 2010). Hearing Loss Deafness is the partial or complete inability to hear. Some people are born deaf, which is known as congenital deafness . Many others begin to suffer from conductive hearing loss because of age, genetic predisposition, or environmental effects, including exposure to extreme noise (noise-induced hearing loss, as shown in Figure 5.18 ), certain illnesses (such as measles or mumps), or damage due to toxins (such as those found in certain solvents and metals). Given the mechanical nature by which the sound wave stimulus is transmitted from the eardrum through the ossicles to the oval window of the cochlea, some degree of hearing loss is inevitable. With conductive hearing loss, hearing problems are associated with a failure in the vibration of the eardrum and/or movement of the ossicles. These problems are often dealt with through devices like hearing aids that amplify incoming sound waves to make vibration of the eardrum and movement of the ossicles more likely to occur. When the hearing problem is associated with a failure to transmit neural signals from the cochlea to the brain, it is called sensorineural hearing loss . One disease that results in sensorineural hearing loss is Ménière's disease . Although not well understood, Ménière's disease results in a degeneration of inner ear structures that can lead to hearing loss, tinnitus (constant ringing or buzzing), vertigo (a sense of spinning), and an increase in pressure within the inner ear (Semaan & Megerian, 2011). This kind of loss cannot be treated with hearing aids, but some individuals might be candidates for a cochlear implant as a treatment option. Cochlear implants are electronic devices that consist of a microphone, a speech processor, and an electrode array. The device receives incoming sound information and directly stimulates the auditory nerve to transmit information to the brain. Link to Learning Watch this video describe cochlear implant surgeries and how they work. What Do You Think? Deaf Culture In the United States and other places around the world, deaf people have their own language, schools, and customs. This is called deaf culture . In the United States, deaf individuals often communicate using American Sign Language (ASL); ASL has no verbal component and is based entirely on visual signs and gestures. The primary mode of communication is signing. One of the values of deaf culture is to continue traditions like using sign language rather than teaching deaf children to try to speak, read lips, or have cochlear implant surgery. When a child is diagnosed as deaf, parents have difficult decisions to make. Should the child be enrolled in mainstream schools and taught to verbalize and read lips? Or should the child be sent to a school for deaf children to learn ASL and have significant exposure to deaf culture? Do you think there might be differences in the way that parents approach these decisions depending on whether or not they are also deaf? 5.5 The Other Senses Learning Objectives By the end of this section, you will be able to: Describe the basic functions of the chemical senses Explain the basic functions of the somatosensory, nociceptive, and thermoceptive sensory systems Describe the basic functions of the vestibular, proprioceptive, and kinesthetic sensory systems Vision and hearing have received an incredible amount of attention from researchers over the years. While there is still much to be learned about how these sensory systems work, we have a much better understanding of them than of our other sensory modalities. In this section, we will explore our chemical senses (taste and smell) and our body senses (touch, temperature, pain, balance, and body position). The Chemical Senses Taste (gustation) and smell (olfaction) are called chemical senses because both have sensory receptors that respond to molecules in the food we eat or in the air we breathe. There is a pronounced interaction between our chemical senses. For example, when we describe the flavor of a given food, we are really referring to both gustatory and olfactory properties of the food working in combination. Taste (Gustation) You have learned since elementary school that there are four basic groupings of taste: sweet, salty, sour, and bitter. Research demonstrates, however, that we have at least six taste groupings. Umami is our fifth taste. Umami is actually a Japanese word that roughly translates to yummy, and it is associated with a taste for monosodium glutamate (Kinnamon & Vandenbeuch, 2009). There is also a growing body of experimental evidence suggesting that we possess a taste for the fatty content of a given food (Mizushige, Inoue, & Fushiki, 2007). Molecules from the food and beverages we consume dissolve in our saliva and interact with taste receptors on our tongue and in our mouth and throat. Taste buds are formed by groupings of taste receptor cells with hair-like extensions that protrude into the central pore of the taste bud ( Figure 5.19 ). Taste buds have a life cycle of ten days to two weeks, so even destroying some by burning your tongue won’t have any long-term effect; they just grow right back. Taste molecules bind to receptors on this extension and cause chemical changes within the sensory cell that result in neural impulses being transmitted to the brain via different nerves, depending on where the receptor is located. Taste information is transmitted to the medulla, thalamus, and limbic system, and to the gustatory cortex, which is tucked underneath the overlap between the frontal and temporal lobes (Maffei, Haley, & Fontanini, 2012; Roper, 2013). Smell (Olfaction) Olfactory receptor cells are located in a mucous membrane at the top of the nose. Small hair-like extensions from these receptors serve as the sites for odor molecules dissolved in the mucus to interact with chemical receptors located on these extensions ( Figure 5.20 ). Once an odor molecule has bound a given receptor, chemical changes within the cell result in signals being sent to the olfactory bulb : a bulb-like structure at the tip of the frontal lobe where the olfactory nerves begin. From the olfactory bulb, information is sent to regions of the limbic system and to the primary olfactory cortex, which is located very near the gustatory cortex (Lodovichi & Belluscio, 2012; Spors et al., 2013). There is tremendous variation in the sensitivity of the olfactory systems of different species. We often think of dogs as having far superior olfactory systems than our own, and indeed, dogs can do some remarkable things with their noses. There is some evidence to suggest that dogs can “smell” dangerous drops in blood glucose levels as well as cancerous tumors (Wells, 2010). Dogs’ extraordinary olfactory abilities may be due to the increased number of functional genes for olfactory receptors (between 800 and 1200), compared to the fewer than 400 observed in humans and other primates (Niimura & Nei, 2007). Many species respond to chemical messages, known as pheromones , sent by another individual (Wysocki & Preti, 2004). Pheromonal communication often involves providing information about the reproductive status of a potential mate. So, for example, when a female rat is ready to mate, she secretes pheromonal signals that draw attention from nearby male rats. Pheromonal activation is actually an important component in eliciting sexual behavior in the male rat (Furlow, 1996, 2012; Purvis & Haynes, 1972; Sachs, 1997). There has also been a good deal of research (and controversy) about pheromones in humans (Comfort, 1971; Russell, 1976; Wolfgang-Kimball, 1992; Weller, 1998). Touch, Thermoception, and Nociception A number of receptors are distributed throughout the skin to respond to various touch-related stimuli ( Figure 5.21 ). These receptors include Meissner’s corpuscles, Pacinian corpuscles, Merkel’s disks, and Ruffini corpuscles. Meissner’s corpuscles respond to pressure and lower frequency vibrations, and Pacinian corpuscles detect transient pressure and higher frequency vibrations. Merkel’s disks respond to light pressure, while Ruffini corpuscles detect stretch (Abraira & Ginty, 2013). In addition to the receptors located in the skin, there are also a number of free nerve endings that serve sensory functions. These nerve endings respond to a variety of different types of touch-related stimuli and serve as sensory receptors for both thermoception (temperature perception) and nociception (a signal indicating potential harm and maybe pain) (Garland, 2012; Petho & Reeh, 2012; Spray, 1986). Sensory information collected from the receptors and free nerve endings travels up the spinal cord and is transmitted to regions of the medulla, thalamus, and ultimately to somatosensory cortex, which is located in the postcentral gyrus of the parietal lobe. Pain Perception Pain is an unpleasant experience that involves both physical and psychological components. Feeling pain is quite adaptive because it makes us aware of an injury, and it motivates us to remove ourselves from the cause of that injury. In addition, pain also makes us less likely to suffer additional injury because we will be gentler with our injured body parts. Generally speaking, pain can be considered to be neuropathic or inflammatory in nature. Pain that signals some type of tissue damage is known as inflammatory pain . In some situations, pain results from damage to neurons of either the peripheral or central nervous system. As a result, pain signals that are sent to the brain get exaggerated. This type of pain is known as neuropathic pain . Multiple treatment options for pain relief range from relaxation therapy to the use of analgesic medications to deep brain stimulation. The most effective treatment option for a given individual will depend on a number of considerations, including the severity and persistence of the pain and any medical/psychological conditions. Some individuals are born without the ability to feel pain. This very rare genetic disorder is known as congenital insensitivity to pain (or congenital analgesia ). While those with congenital analgesia can detect differences in temperature and pressure, they cannot experience pain. As a result, they often suffer significant injuries. Young children have serious mouth and tongue injuries because they have bitten themselves repeatedly. Not surprisingly, individuals suffering from this disorder have much shorter life expectancies due to their injuries and secondary infections of injured sites (U.S. National Library of Medicine, 2013). Link to Learning Watch this video to learn more about congenital insensitivity to pain. The Vestibular Sense, Proprioception, and Kinesthesia The vestibular sense contributes to our ability to maintain balance and body posture. As Figure 5.22 shows, the major sensory organs (utricle, saccule, and the three semicircular canals) of this system are located next to the cochlea in the inner ear. The vestibular organs are fluid-filled and have hair cells, similar to the ones found in the auditory system, which respond to movement of the head and gravitational forces. When these hair cells are stimulated, they send signals to the brain via the vestibular nerve. Although we may not be consciously aware of our vestibular system’s sensory information under normal circumstances, its importance is apparent when we experience motion sickness and/or dizziness related to infections of the inner ear (Khan & Chang, 2013). In addition to maintaining balance, the vestibular system collects information critical for controlling movement and the reflexes that move various parts of our bodies to compensate for changes in body position. Therefore, both proprioception (perception of body position) and kinesthesia (perception of the body’s movement through space) interact with information provided by the vestibular system. These sensory systems also gather information from receptors that respond to stretch and tension in muscles, joints, skin, and tendons (Lackner & DiZio, 2005; Proske, 2006; Proske & Gandevia, 2012). Proprioceptive and kinesthetic information travels to the brain via the spinal column. Several cortical regions in addition to the cerebellum receive information from and send information to the sensory organs of the proprioceptive and kinesthetic systems. 5.6 Gestalt Principles of Perception Learning Objectives By the end of this section, you will be able to: Explain the figure-ground relationship Define Gestalt principles of grouping Describe how perceptual set is influenced by an individual’s characteristics and mental state In the early part of the 20th century, Max Wertheimer published a paper demonstrating that individuals perceived motion in rapidly flickering static images—an insight that came to him as he used a child’s toy tachistoscope. Wertheimer, and his assistants Wolfgang Köhler and Kurt Koffka, who later became his partners, believed that perception involved more than simply combining sensory stimuli. This belief led to a new movement within the field of psychology known as Gestalt psychology . The word gestalt literally means form or pattern, but its use reflects the idea that the whole is different from the sum of its parts. In other words, the brain creates a perception that is more than simply the sum of available sensory inputs, and it does so in predictable ways. Gestalt psychologists translated these predictable ways into principles by which we organize sensory information. As a result, Gestalt psychology has been extremely influential in the area of sensation and perception (Rock & Palmer, 1990). One Gestalt principle is the figure-ground relationship . According to this principle, we tend to segment our visual world into figure and ground. Figure is the object or person that is the focus of the visual field, while the ground is the background. As Figure 5.23 shows, our perception can vary tremendously, depending on what is perceived as figure and what is perceived as ground. Presumably, our ability to interpret sensory information depends on what we label as figure and what we label as ground in any particular case, although this assumption has been called into question (Peterson & Gibson, 1994; Vecera & O’Reilly, 1998). Another Gestalt principle for organizing sensory stimuli into meaningful perception is proximity . This principle asserts that things that are close to one another tend to be grouped together, as Figure 5.24 illustrates. How we read something provides another illustration of the proximity concept. For example, we read this sentence like this, notl iket hiso rt hat. We group the letters of a given word together because there are no spaces between the letters, and we perceive words because there are spaces between each word. Here are some more examples: Cany oum akes enseo ft hiss entence? What doth es e wor dsmea n? We might also use the principle of similarity to group things in our visual fields. According to this principle, things that are alike tend to be grouped together ( Figure 5.25 ). For example, when watching a football game, we tend to group individuals based on the colors of their uniforms. When watching an offensive drive, we can get a sense of the two teams simply by grouping along this dimension. Two additional Gestalt principles are the law of continuity (or good continuation ) and closure . The law of continuity suggests that we are more likely to perceive continuous, smooth flowing lines rather than jagged, broken lines ( Figure 5.26 ). The principle of closure states that we organize our perceptions into complete objects rather than as a series of parts ( Figure 5.27 ). Link to Learning Watch this video showing real world illustrations of Gestalt principles. According to Gestalt theorists, pattern perception , or our ability to discriminate among different figures and shapes, occurs by following the principles described above. You probably feel fairly certain that your perception accurately matches the real world, but this is not always the case. Our perceptions are based on perceptual hypotheses : educated guesses that we make while interpreting sensory information. These hypotheses are informed by a number of factors, including our personalities, experiences, and expectations. We use these hypotheses to generate our perceptual set. For instance, research has demonstrated that those who are given verbal priming produce a biased interpretation of complex ambiguous figures (Goolkasian & Woodbury, 2010). Dig Deeper The Depths of Perception: Bias, Prejudice, and Cultural Factors In this chapter, you have learned that perception is a complex process. Built from sensations, but influenced by our own experiences, biases, prejudices, and cultures , perceptions can be very different from person to person. Research suggests that implicit racial prejudice and stereotypes affect perception. For instance, several studies have demonstrated that non-Black participants identify weapons faster and are more likely to identify non-weapons as weapons when the image of the weapon is paired with the image of a Black person (Payne, 2001; Payne, Shimizu, & Jacoby, 2005). Furthermore, White individuals’ decisions to shoot an armed target in a video game is made more quickly when the target is Black (Correll, Park, Judd, & Wittenbrink, 2002; Correll, Urland, & Ito, 2006). This research is important, considering the number of very high-profile cases in the last few decades in which young Blacks were killed by people who claimed to believe that the unarmed individuals were armed and/or represented some threat to their personal safety.
introduction_to_sociology
Learning Objectives 16.1 Education around the World Identify differences in educational resources around the world Describe the concept of universal access to education 16.2 Theoretical Perspectives on Education Define manifest and latent functions of education Explain and discuss how functionalism, conflict theory, feminism, and interactionism view issues of education 16.3 Issues in Education Identify and discuss historical and contemporary issues in education Introduction to Education From the moment a child is born, his or her education begins. At first, education is an informal process in which an infant watches others and imitates them. As the infant grows into a young child, the process of education becomes more formal through play dates and preschool. Once in grade school, academic lessons become the focus of education as a child moves through the school system. But even then, education is about much more than the simple learning of facts. Our education system also socializes us to our society. We learn cultural expectations and norms, which are reinforced by our teachers, our textbooks, and our classmates. (For students outside the dominant culture, this aspect of the education system can pose significant challenges.) You might remember learning your multiplication tables in second grade and also learning the social rules of taking turns on the swings at recess. You might recall learning about the U.S. Constitution in an American Government course as well as learning when and how to speak up in class. Schools also can be agents of change, teaching individuals to think outside of the family norms into which they were born. Educational environments can broaden horizons and even help to break cycles of poverty and racism. Of course, America’s schools are often criticized—for not producing desired test results, or for letting certain kids slip through the cracks. In all, sociologists understand education to be both a social problem and a social solution—and a rich area of study.
[ { "answer": { "ans_choice": 0, "ans_text": "Resources and money" }, "bloom": null, "hl_context": "Education is a social institution through which a society ’ s children are taught basic academic knowledge , learning skills , and cultural norms . Every nation in the world is equipped with some form of education system , though those systems vary greatly . <hl> The major factors affecting education systems are the resources and money that are utilized to support those systems in different nations . <hl> As you might expect , a country ’ s wealth has much to do with the amount of money spent on education . Countries that do not have such basic amenities as running water are unable to support robust education systems or , in many cases , any formal schooling at all . The result of this worldwide educational inequality is a social concern for many countries , including the United States .", "hl_sentences": "The major factors affecting education systems are the resources and money that are utilized to support those systems in different nations .", "question": { "cloze_format": "The major factor(s) affecting education systems throughout the world are/is ___.", "normal_format": "What are the major factors affecting education systems throughout the world?", "question_choices": [ "Resources and money", "Student interest", "Teacher interest", "Transportation" ], "question_id": "fs-id1728418", "question_text": "What are the major factors affecting education systems throughout the world?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 1, "ans_text": "They recruit top teachers." }, "bloom": "1", "hl_context": "<hl> Analysts determined that the nations and city-states at the top of the rankings had several things in common . <hl> For one , they had well-established standards for education with clear goals for all students . <hl> They also recruited teachers from the top 5 to 10 percent of university graduates each year , which is not the case for most countries ( National Public Radio 2010 ) . <hl>", "hl_sentences": "Analysts determined that the nations and city-states at the top of the rankings had several things in common . They also recruited teachers from the top 5 to 10 percent of university graduates each year , which is not the case for most countries ( National Public Radio 2010 ) .", "question": { "cloze_format": "Nations that are top-ranked in science and math have in common that ___.", "normal_format": "What do nations that are top-ranked in science and math have in common?", "question_choices": [ "They are all in Asia.", "They recruit top teachers.", "They spend more money per student.", "They use cutting-edge technology in classrooms. " ], "question_id": "fs-id1559346", "question_text": "What do nations that are top-ranked in science and math have in common?" }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 1, "ans_text": "refers to the learning of cultural norms" }, "bloom": "1", "hl_context": "<hl> In contrast , informal education describes learning about cultural values , norms , and expected behaviors by participating in a society . <hl> This type of learning occurs both through the formal education system and at home . Our earliest learning experiences generally happen via parents , relatives , and others in our community . Through informal education , we learn how to dress for different occasions , how to perform regular life routines like shopping for and preparing food , and how to keep our bodies clean .", "hl_sentences": "In contrast , informal education describes learning about cultural values , norms , and expected behaviors by participating in a society .", "question": { "cloze_format": "Informal education _________________.", "normal_format": "Which of the following is correct about informal education?", "question_choices": [ "describes when students teach their peers ", "refers to the learning of cultural norms", "only takes place at home", "relies on a planned instructional process" ], "question_id": "fs-id1457038", "question_text": "Informal education _________________." }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 0, "ans_text": "cultural transmission" }, "bloom": null, "hl_context": "<hl> Cultural transmission refers to the way people come to learn the values , beliefs , and social norms of their culture . <hl> <hl> Both informal and formal education include cultural transmission . <hl> <hl> For example , a student will learn about cultural aspects of modern history in a U . S . History classroom . <hl> <hl> In that same classroom , the student might learn the cultural norm for asking a classmate out on a date through passing notes and whispered conversations . <hl>", "hl_sentences": "Cultural transmission refers to the way people come to learn the values , beliefs , and social norms of their culture . Both informal and formal education include cultural transmission . For example , a student will learn about cultural aspects of modern history in a U . S . History classroom . In that same classroom , the student might learn the cultural norm for asking a classmate out on a date through passing notes and whispered conversations .", "question": { "cloze_format": "Learning from classmates that most students buy lunch on Fridays is an example of ________.", "normal_format": "What is learning from classmates that most students buy lunch on Fridays an example of?", "question_choices": [ "cultural transmission", "educational access ", "formal education", "informal education" ], "question_id": "fs-id1327418", "question_text": "Learning from classmates that most students buy lunch on Fridays is an example of ________." }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 0, "ans_text": "access to education" }, "bloom": null, "hl_context": "<hl> A precedent for universal access to education in the United States was set with the 1972 U . S . District Court for the District of Columbia ’ s decision in Mills v . Board of Education of the District of Columbia . <hl> This case was brought on the behalf of seven school-age children with special needs who argued that the school board was denying their access to free public education . The school board maintained that the children ’ s “ exceptional ” needs , which included mental retardation and mental illness , precluded their right to be educated for free in a public school setting . The board argued that the cost of educating these children would be too expensive and that the children would therefore have to remain at home without access to education .", "hl_sentences": "A precedent for universal access to education in the United States was set with the 1972 U . S . District Court for the District of Columbia ’ s decision in Mills v . Board of Education of the District of Columbia .", "question": { "cloze_format": "The 1972 case Mills v. Board of Education of the District of Columbia set a precedent for __________.", "normal_format": "The 1972 case Mills v. Board of Education of the District of Columbia set a precedent for what?", "question_choices": [ "access to education", "average spending on students", "desegregation of schools ", "teacher salary" ], "question_id": "fs-id1518009", "question_text": "The 1972 case Mills v. Board of Education of the District of Columbia set a precedent for __________." }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 1, "ans_text": "Courtship" }, "bloom": "1", "hl_context": "<hl> Education also fulfills latent functions . <hl> As you well know , much goes on in a school that has little to do with formal education . <hl> For example , you might notice an attractive fellow student when he gives a particularly interesting answer in class — catching up with him and making a date speaks to the latent function of courtship fulfilled by exposure to a peer group in the educational setting . <hl> <hl> Education also provides one of the major methods used by people for upward social mobility . <hl> <hl> This function is referred to as social placement . <hl> College and graduate schools are viewed as vehicles for moving students closer to the careers that will give them the financial freedom and security they seek . As a result , college students are often more motivated to study areas that they believe will be advantageous on the social ladder . A student might value business courses over a class in Victorian poetry because she sees business class as a stronger vehicle for financial success . <hl> There are several major manifest functions associated with education . <hl> <hl> The first is socialization . <hl> Beginning in preschool and kindergarten , students are taught to practice various societal roles . The French sociologist Émile Durkheim ( 1858 – 1917 ) , who established the academic discipline of sociology , characterized schools as “ socialization agencies that teach children how to get along with others and prepare them for adult economic roles ” ( Durkheim 1898 ) . Indeed , it seems that schools have taken on this responsibility in full .", "hl_sentences": "Education also fulfills latent functions . For example , you might notice an attractive fellow student when he gives a particularly interesting answer in class — catching up with him and making a date speaks to the latent function of courtship fulfilled by exposure to a peer group in the educational setting . Education also provides one of the major methods used by people for upward social mobility . This function is referred to as social placement . There are several major manifest functions associated with education . The first is socialization .", "question": { "cloze_format": "___ is not a manifest function of education.", "normal_format": "Which of the following is not a manifest function of education?", "question_choices": [ "Cultural innovation", "Courtship", "Social placement", "Socialization" ], "question_id": "fs-id1485404", "question_text": "Which of the following is not a manifest function of education?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 2, "ans_text": "social placement" }, "bloom": null, "hl_context": "<hl> Education also provides one of the major methods used by people for upward social mobility . <hl> <hl> This function is referred to as social placement . <hl> College and graduate schools are viewed as vehicles for moving students closer to the careers that will give them the financial freedom and security they seek . <hl> As a result , college students are often more motivated to study areas that they believe will be advantageous on the social ladder . <hl> <hl> A student might value business courses over a class in Victorian poetry because she sees business class as a stronger vehicle for financial success . <hl>", "hl_sentences": "Education also provides one of the major methods used by people for upward social mobility . This function is referred to as social placement . As a result , college students are often more motivated to study areas that they believe will be advantageous on the social ladder . A student might value business courses over a class in Victorian poetry because she sees business class as a stronger vehicle for financial success .", "question": { "cloze_format": "Because she plans on achieving success in marketing, Tammie is taking courses on managing social media. This is an example of ________.", "normal_format": "Because she plans on achieving success in marketing, Tammie is taking courses on managing social media. What is this an example of?", "question_choices": [ "cultural innovation", "social control", "social placement", "socialization" ], "question_id": "fs-id1706313", "question_text": "Because she plans on achieving success in marketing, Tammie is taking courses on managing social media. This is an example of ________." }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 0, "ans_text": "Conflict theory" }, "bloom": "1", "hl_context": "<hl> Conflict theorists do not believe that public schools reduce social inequality . <hl> Rather , they believe that the educational system reinforces and perpetuates social inequalities arising from differences in class , gender , race , and ethnicity . <hl> Where functionalists see education as serving a beneficial role , conflict theorists view it more negatively . <hl> <hl> To them , educational systems preserve the status quo and push people of lower status into obedience . <hl>", "hl_sentences": "Conflict theorists do not believe that public schools reduce social inequality . Where functionalists see education as serving a beneficial role , conflict theorists view it more negatively . To them , educational systems preserve the status quo and push people of lower status into obedience .", "question": { "cloze_format": "The theory of education that focuses on the ways in which education maintains the status quo is the ___ .", "normal_format": "Which theory of education focuses on the ways in which education maintains the status quo?", "question_choices": [ "Conflict theory", "Feminist theory", "Functionalist theory", "Symbolic interactionism" ], "question_id": "fs-id1734421", "question_text": "Which theory of education focuses on the ways in which education maintains the status quo?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 3, "ans_text": "Symbolic interactionism" }, "bloom": "1", "hl_context": "<hl> The labeling with which symbolic interactionists concern themselves extends to the very degrees that symbolize completion of education . <hl> Credentialism embodies the emphasis on certificates or degrees to show that a person has a certain skill , has attained a certain level of education , or has met certain job qualifications . These certificates or degrees serve as a symbol of what a person has achieved , allowing the labeling of that individual . <hl> Symbolic interactionism sees education as one way labeling theory is seen in action . <hl> A symbolic interactionist might say that this labeling has a direct correlation to those who are in power and those who are being labeled . For example , low standardized test scores or poor performance in a particular class often lead to a student being labeled as a low achiever . Such labels are difficult to “ shake off , ” which can create a self-fulfilling prophecy ( Merton 1968 ) .", "hl_sentences": "The labeling with which symbolic interactionists concern themselves extends to the very degrees that symbolize completion of education . Symbolic interactionism sees education as one way labeling theory is seen in action .", "question": { "cloze_format": "The theory of education that focuses on the labels acquired through the educational process is the ___.", "normal_format": "Which theory of education focuses on the labels acquired through the educational process?", "question_choices": [ "Conflict theory", "Feminist theory", "Functionalist theory", "Symbolic interactionism" ], "question_id": "fs-id1569582", "question_text": "Which theory of education focuses on the labels acquired through the educational process?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 3, "ans_text": "Tracking" }, "bloom": null, "hl_context": "<hl> Conflict theorists point to tracking , a formalized sorting system that places students on “ tracks ” ( advanced versus low achievers ) that perpetuate inequalities . <hl> <hl> While educators may believe that students do better in tracked classes because they are with students of similar ability and may have access to more individual attention from teachers , conflict theorists feel that tracking leads to self-fulfilling prophecies in which students live up ( or down ) to teacher and societal expectations ( Education Week 2004 ) . <hl>", "hl_sentences": "Conflict theorists point to tracking , a formalized sorting system that places students on “ tracks ” ( advanced versus low achievers ) that perpetuate inequalities . While educators may believe that students do better in tracked classes because they are with students of similar ability and may have access to more individual attention from teachers , conflict theorists feel that tracking leads to self-fulfilling prophecies in which students live up ( or down ) to teacher and societal expectations ( Education Week 2004 ) .", "question": { "cloze_format": "(The) ___ describes the assignment of students to specific education programs and classes on the basis of test scores, previous grades, or perceived ability.", "normal_format": "What term describes the assignment of students to specific education programs and classes on the basis of test scores, previous grades, or perceived ability?", "question_choices": [ "Hidden curriculum", "Labeling", "Self-fulfilling prophecy", "Tracking" ], "question_id": "fs-id1278308", "question_text": "What term describes the assignment of students to specific education programs and classes on the basis of test scores, previous grades, or perceived ability?" }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 3, "ans_text": "all of the above" }, "bloom": "1", "hl_context": "<hl> Functionalists also contend that school , particularly in recent years , is taking over some of the functions that were traditionally undertaken by family . <hl> Society relies on schools to teach about human sexuality as well as basic skills such as budgeting and job applications — topics that at one time were addressed by the family . <hl> While it is clear that education plays an integral role in individuals ’ lives as well as society as a whole , sociologists view that role from many diverse points of view . <hl> <hl> Functionalists believe that education equips people to perform different functional roles in society . <hl> Conflict theorists view education as a means of widening the gap in social inequality . Feminist theorists point to evidence that sexism in education continues to prevent women from achieving a full measure of social equality . Symbolic interactionists study the dynamics of the classroom , the interactions between students and teachers , and how those affect everyday life . In this section , you will learn about each of these perspectives .", "hl_sentences": "Functionalists also contend that school , particularly in recent years , is taking over some of the functions that were traditionally undertaken by family . While it is clear that education plays an integral role in individuals ’ lives as well as society as a whole , sociologists view that role from many diverse points of view . Functionalists believe that education equips people to perform different functional roles in society .", "question": { "cloze_format": "Functionalist theory sees education as serving the needs of _________.", "normal_format": "Functionalist theory sees education as serving the needs of which of the following?", "question_choices": [ "families", "society", "the individual", "all of the above" ], "question_id": "fs-id1741394", "question_text": "Functionalist theory sees education as serving the needs of _________." }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 3, "ans_text": "transmission of moral education" }, "bloom": "3", "hl_context": "<hl> The cycle of rewarding those who possess cultural capital is found in formal educational curricula as well as in the hidden curriculum , which refers to the type of nonacademic knowledge that one learns through informal learning and cultural transmission . <hl> This hidden curriculum reinforces the positions of those with higher cultural capital , and serves to bestow status unequally .", "hl_sentences": "The cycle of rewarding those who possess cultural capital is found in formal educational curricula as well as in the hidden curriculum , which refers to the type of nonacademic knowledge that one learns through informal learning and cultural transmission .", "question": { "cloze_format": "Rewarding students for meeting deadlines and respecting authority figures is an example of ________.", "normal_format": "What is rewarding students for meeting deadlines and respecting authority figures an example of?", "question_choices": [ "a latent function ", "a manifest function", "informal education", "transmission of moral education" ], "question_id": "fs-id1464211", "question_text": "Rewarding students for meeting deadlines and respecting authority figures is an example of ________." }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 2, "ans_text": "Sorting" }, "bloom": "1", "hl_context": "<hl> Another role of schools , according to functionalist theory , is that of sorting , or classifying students based on academic merit or potential . <hl> The most capable students are identified early in schools through testing and classroom achievements . Such students are placed in accelerated programs in anticipation of successful college attendance .", "hl_sentences": "Another role of schools , according to functionalist theory , is that of sorting , or classifying students based on academic merit or potential .", "question": { "cloze_format": "___ is a term that describes the separation of students based on merit.", "normal_format": "What term describes the separation of students based on merit?", "question_choices": [ "Cultural transmission", "Social control", "Sorting", "Hidden curriculum" ], "question_id": "fs-id1825396", "question_text": "What term describes the separation of students based on merit?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 1, "ans_text": "perpetuate divisions of socioeconomic status" }, "bloom": "1", "hl_context": "<hl> Conflict theorists point to tracking , a formalized sorting system that places students on “ tracks ” ( advanced versus low achievers ) that perpetuate inequalities . <hl> While educators may believe that students do better in tracked classes because they are with students of similar ability and may have access to more individual attention from teachers , conflict theorists feel that tracking leads to self-fulfilling prophecies in which students live up ( or down ) to teacher and societal expectations ( Education Week 2004 ) .", "hl_sentences": "Conflict theorists point to tracking , a formalized sorting system that places students on “ tracks ” ( advanced versus low achievers ) that perpetuate inequalities .", "question": { "cloze_format": "Conflict theorists see sorting as a way to ________.", "normal_format": "Conflict theorists see sorting as a way to do which of the following?", "question_choices": [ "challenge gifted students", "perpetuate divisions of socioeconomic status", "help students who need additional support", "teach respect for authority" ], "question_id": "fs-id1752329", "question_text": "Conflict theorists see sorting as a way to ________." }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 3, "ans_text": "They reward affluent students with questions that assume knowledge associated with upper-class culture. " }, "bloom": "3", "hl_context": "<hl> IQ tests have been attacked for being biased — for testing cultural knowledge rather than actual intelligence . <hl> For example , a test item may ask students what instruments belong in an orchestra . <hl> To correctly answer this question requires certain cultural knowledge — knowledge most often held by more affluent people who typically have more exposure to orchestral music . <hl> Though experts in testing claim that bias has been eliminated from tests , conflict theorists maintain that this is impossible . These tests , to conflict theorists , are another way in which education does not provide opportunities , but instead maintains an established configuration of power .", "hl_sentences": "IQ tests have been attacked for being biased — for testing cultural knowledge rather than actual intelligence . To correctly answer this question requires certain cultural knowledge — knowledge most often held by more affluent people who typically have more exposure to orchestral music .", "question": { "cloze_format": "Conflict theorists see IQ tests as being biased because ___ .", "normal_format": "Conflict theorists see IQ tests as being biased. Why?", "question_choices": [ "They are scored in a way that is subject to human error. ", "They do not give children with learning disabilities a fair chance to demonstrate their true intelligence.", "They don’t involve enough test items to cover multiple intelligences. ", "They reward affluent students with questions that assume knowledge associated with upper-class culture. " ], "question_id": "fs-id1555037", "question_text": "Conflict theorists see IQ tests as being biased. Why?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 0, "ans_text": "racial segregation in schools was allowed" }, "bloom": "1", "hl_context": "<hl> Until the 1954 Brown v . Board of Education ruling , schools had operated under the precedent set by Plessy v . Ferguson in 1896 , which allowed racial segregation in schools and private businesses ( the case dealt specifically with railroads ) and introduced the much maligned phrase “ separate but equal ” into the United States lexicon . <hl> The 1954 Brown v . Board decision overruled this , declaring that state laws that had established separate schools for black and white students were , in fact , unequal and unconstitutional .", "hl_sentences": "Until the 1954 Brown v . Board of Education ruling , schools had operated under the precedent set by Plessy v . Ferguson in 1896 , which allowed racial segregation in schools and private businesses ( the case dealt specifically with railroads ) and introduced the much maligned phrase “ separate but equal ” into the United States lexicon .", "question": { "cloze_format": "Plessy v. Ferguson set the precedent that _____________.", "normal_format": "What does Plessy v. Ferguson set the precedent of?", "question_choices": [ "racial segregation in schools was allowed", "separate schools for black and white students were unconstitutional", "students do not have a right to free speech in public schools ", "students have a right to free speech in public schools " ], "question_id": "fs-id1499692", "question_text": "Plessy v. Ferguson set the precedent that _____________." }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 2, "ans_text": "per-student spending is equitable" }, "bloom": "1", "hl_context": "Today ’ s public schools , at least in theory , are positioned to help remedy those gaps . Predicated on the notion of universal access , this system is mandated to accept and retain all students regardless of race , religion , social class , and the like . <hl> Moreover , public schools are held accountable to equitable per-student spending ( Resnick 2004 ) . <hl> Private schools , usually only accessible to students from high-income families , and schools in more affluent areas generally enjoy access to greater resources and better opportunities . In fact , some of the key predictors for student performance include socioeconomic status and family background . Children from families of lower socioeconomic status often enter school with learning deficits they struggle to overcome throughout their educational tenure . These patterns , uncovered in the landmark Coleman Report of 1966 , are still highly relevant today , as sociologists still generally agree that there is a great divide in the performance of white students from affluent backgrounds and their non-white , less affluent , counterparts ( Coleman 1966 ) .", "hl_sentences": "Moreover , public schools are held accountable to equitable per-student spending ( Resnick 2004 ) .", "question": { "cloze_format": "Public schools must guarantee that ___________.", "normal_format": "What must public schools guarantee?", "question_choices": [ "all students graduate from high school", "all students receive an equal education", "per-student spending is equitable", "the amount spent on each student is equal to that spent regionally" ], "question_id": "fs-id1704473", "question_text": "Public schools must guarantee that ___________." }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 1, "ans_text": "socioeconomic status and family background" }, "bloom": "1", "hl_context": "Today ’ s public schools , at least in theory , are positioned to help remedy those gaps . Predicated on the notion of universal access , this system is mandated to accept and retain all students regardless of race , religion , social class , and the like . Moreover , public schools are held accountable to equitable per-student spending ( Resnick 2004 ) . Private schools , usually only accessible to students from high-income families , and schools in more affluent areas generally enjoy access to greater resources and better opportunities . <hl> In fact , some of the key predictors for student performance include socioeconomic status and family background . <hl> <hl> Children from families of lower socioeconomic status often enter school with learning deficits they struggle to overcome throughout their educational tenure . <hl> These patterns , uncovered in the landmark Coleman Report of 1966 , are still highly relevant today , as sociologists still generally agree that there is a great divide in the performance of white students from affluent backgrounds and their non-white , less affluent , counterparts ( Coleman 1966 ) .", "hl_sentences": "In fact , some of the key predictors for student performance include socioeconomic status and family background . Children from families of lower socioeconomic status often enter school with learning deficits they struggle to overcome throughout their educational tenure .", "question": { "cloze_format": "Key predictors for student success include ____________.", "normal_format": "Key predictors for student success include what?", "question_choices": [ "how many school-age siblings the student has", "socioeconomic status and family background", "the age of the student when she or he enters kindergarten", "how many students attend the school" ], "question_id": "fs-id1743601", "question_text": "Key predictors for student success include ____________." }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 2, "ans_text": "social promotion" }, "bloom": "3", "hl_context": "<hl> Social promotion is another issue identified by sociologists . <hl> <hl> This is the concept of passing students to the next grade regardless of their meeting standards for that grade . <hl> Critics of this practice argue that students should never move to the next grade if they have not mastered the skills required to “ graduate ” from the previous grade . Proponents of the practice question what a school is to do with a student who is three to four years older than other students in his or her grade , saying this creates more issues than the practice of social promotion .", "hl_sentences": "Social promotion is another issue identified by sociologists . This is the concept of passing students to the next grade regardless of their meeting standards for that grade .", "question": { "cloze_format": "Allowing a student to move to the next grade regardless of whether or not they have met the requirements for that grade is called ____________.", "normal_format": "What is it called to allow a student to move to the next grade regardless of whether or not they have met the requirements for that grade?", "question_choices": [ "affirmative action", "social control", "social promotion", "socialization " ], "question_id": "fs-id1551708", "question_text": "Allowing a student to move to the next grade regardless of whether or not they have met the requirements for that grade is called ____________." }, "references_are_paraphrase": null } ]
16
16.1 Education around the World Education is a social institution through which a society’s children are taught basic academic knowledge, learning skills, and cultural norms. Every nation in the world is equipped with some form of education system, though those systems vary greatly. The major factors affecting education systems are the resources and money that are utilized to support those systems in different nations. As you might expect, a country’s wealth has much to do with the amount of money spent on education. Countries that do not have such basic amenities as running water are unable to support robust education systems or, in many cases, any formal schooling at all. The result of this worldwide educational inequality is a social concern for many countries, including the United States. International differences in education systems are not solely a financial issue. The value placed on education, the amount of time devoted to it, and the distribution of education within a country also play a role in those differences. For example, students in South Korea spend 220 days a year in school, compared to the 180 days a year of their United States counterparts (Pellissier 2010). As of 2006, the United States ranked fifth among 27 countries for college participation, but ranked 16th in the number of students who receive college degrees (National Center for Public Policy and Higher Education 2006). These statistics may be related to how much time is spent on education in the United States. Then there is the issue of educational distribution within a nation. In December 2010, the results of a test called the Program for International Student Assessment (PISA), which is administered to 15-year-old students worldwide, were released. Those results showed that students in the United States had fallen from 15th to 25th in the rankings for science and math (National Public Radio 2010). Students at the top of the rankings hailed from Shanghai, Finland, Hong Kong, and Singapore. Analysts determined that the nations and city-states at the top of the rankings had several things in common. For one, they had well-established standards for education with clear goals for all students. They also recruited teachers from the top 5 to 10 percent of university graduates each year, which is not the case for most countries (National Public Radio 2010). Finally, there is the issue of social factors. One analyst from the Organization for Economic Cooperation and Development, the organization that created the test, attributed 20 percent of performance differences and the United States’ low rankings to differences in social background. Researchers noted that educational resources, including money and quality teachers, are not distributed equitably in the United States. In the top-ranking countries, limited access to resources did not necessarily predict low performance. Analysts also noted what they described as “resilient students,” or those students who achieve at a higher level than one might expect given their social background. In Shanghai and Singapore, the proportion of resilient students is about 70 percent. In the United States, it is below 30 percent. These insights suggest that the United States’ educational system may be on a descending path that could detrimentally affect the country’s economy and its social landscape (National Public Radio 2010). Big Picture Education in Afghanistan Since the fall of the Taliban in Afghanistan, there has been a spike in demand for education. This spike is so great, in fact, that it has exceeded the nation’s resources for meeting the demand. More than 6.2 million students are enrolled in grades one through 12 in Afghanistan, and about 2.2 million of those students are female (World Bank 2011). Both of these figures are the largest in Afghan history—far exceeding the time before the Taliban was in power. At the same time, there is currently a severe shortage of teachers in Afghanistan, and the educators in the system are often undertrained and frequently do not get paid on time. Currently, they are optimistic and enthusiastic about educational opportunities and approach teaching with a positive attitude, but there is fear that this optimism will not last. With these challenges, there is a push to improve the quality of education in Afghanistan as quickly as possible. Educational leaders are looking to other post-conflict countries for guidance, hoping to learn from other nations that have faced similar circumstances. Their input suggests that the keys to rebuilding education are an early focus on quality and a commitment to educational access. Currently, educational quality in Afghanistan is generally considered poor, as is educational access. Literacy and math skills are low, as are skills in critical thinking and problem solving. Education of females poses additional challenges since cultural norms decree that female students should be taught by female teachers. Currently, there is a lack of female teachers to meet that gender-based demand. In some provinces, the female student population falls below 15 percent of students (World Bank 2011). Female education is also important to Afghanistan’s future because mothers are primary socialization agents: an educated mother is more likely to instill a thirst for education in her children, setting up a positive cycle of education for generations to come. Improvements must be made to Afghanistan’s infrastructure in order to improve education, which has historically been managed at the local level. The World Bank, which strives to help developing countries break free of poverty and become self-sustaining has been hard at work to assist the people of Afghanistan in improving educational quality and access. The Education Quality Improvement Program provides training for teachers and grants to communities. The program is active in all 34 provinces of Afghanistan, supporting grants for both quality enhancement and development of infrastructure as well as providing a teacher education program. Another program called Strengthening Higher Education focuses on six universities in Afghanistan and four regional colleges. The emphasis of this program is on fostering relationships with universities in other countries, including the United States and India, to focus on fields including engineering, natural sciences, and English as a second language. The program also seeks to improve libraries and laboratories through grants. These efforts by the World Bank illustrate the ways global attention and support can benefit an educational system. In developing countries like Afghanistan, partnerships with countries that have established successful educational programs play a key role in efforts to rebuild their future. Formal and Informal Education As already mentioned, education is not solely concerned with the basic academic concepts that a student learns in the classroom. Societies also educate their children, outside of the school system, in matters of everyday practical living. These two types of learning are referred to as formal education and informal education. Formal education describes the learning of academic facts and concepts through a formal curriculum. Arising from the tutelage of ancient Greek thinkers, centuries of scholars have examined topics through formalized methods of learning. Education in earlier times was only available to the higher classes; they had the means for access to scholarly materials, plus the luxury of leisure time that could be used for learning. The Industrial Revolution and its accompanying social changes made education more accessible to the general population. Many families in the emerging middle class found new opportunities for schooling. The modern U.S. educational system is the result of this progression. Today, basic education is considered a right and responsibility for all citizens. Expectations of this system focus on formal education, with curricula and testing designed to ensure that students learn the facts and concepts that society believes are basic knowledge. In contrast, informal education describes learning about cultural values, norms, and expected behaviors by participating in a society. This type of learning occurs both through the formal education system and at home. Our earliest learning experiences generally happen via parents, relatives, and others in our community. Through informal education, we learn how to dress for different occasions, how to perform regular life routines like shopping for and preparing food, and how to keep our bodies clean. Cultural transmission refers to the way people come to learn the values, beliefs, and social norms of their culture. Both informal and formal education include cultural transmission. For example, a student will learn about cultural aspects of modern history in a U.S. History classroom. In that same classroom, the student might learn the cultural norm for asking a classmate out on a date through passing notes and whispered conversations. Access to Education Another global concern in education is universal access . This term refers to people’s equal ability to participate in an education system. On a world level, access might be more difficult for certain groups based on class or gender (as was the case in the United States earlier in our nation’s history, a dynamic we still struggle to overcome). The modern idea of universal access arose in the United States as a concern for people with disabilities. In the United States, one way in which universal education is supported is through federal and state governments covering the cost of free public education. Of course, the way this plays out in terms of school budgets and taxes makes this an often-contested topic on the national, state, and community levels. A precedent for universal access to education in the United States was set with the 1972 U.S. District Court for the District of Columbia’s decision in Mills v. Board of Education of the District of Columbia . This case was brought on the behalf of seven school-age children with special needs who argued that the school board was denying their access to free public education. The school board maintained that the children’s “exceptional” needs, which included mental retardation and mental illness, precluded their right to be educated for free in a public school setting. The board argued that the cost of educating these children would be too expensive and that the children would therefore have to remain at home without access to education. This case was resolved in a hearing without any trial. The judge, Joseph Cornelius Waddy, upheld the students’ right to education, finding that they were to be given either public education services or private education paid for by the Washington, D.C., board of education. He noted that Constitutional rights must be afforded citizens despite the greater expense involved … the District of Columbia’s interest in educating the excluded children clearly must outweigh its interest in preserving its financial resources. … The inadequacies of the District of Columbia Public School System whether occasioned by insufficient funding or administrative inefficiency, certainly cannot be permitted to bear more heavily on the “exceptional” or handicapped child than on the normal child ( Mills v. Board of Education 1972). Today, the optimal way to include differently able students in standard classrooms is still being researched and debated. “Inclusion” is a method that involves complete immersion in a standard classroom, whereas “mainstreaming” balances time in a special-needs classroom with standard classroom participation. There continues to be social debate surrounding how to implement the ideal of universal access to education. 16.2 Theoretical Perspectives on Education While it is clear that education plays an integral role in individuals’ lives as well as society as a whole, sociologists view that role from many diverse points of view. Functionalists believe that education equips people to perform different functional roles in society. Conflict theorists view education as a means of widening the gap in social inequality. Feminist theorists point to evidence that sexism in education continues to prevent women from achieving a full measure of social equality. Symbolic interactionists study the dynamics of the classroom, the interactions between students and teachers, and how those affect everyday life. In this section, you will learn about each of these perspectives. Functionalism Functionalists view education as one of the more important social institutions in a society. They contend that education contributes two kinds of functions: manifest (or primary) functions, which are the intended and visible functions of education; and latent (or secondary) functions, which are the hidden and unintended functions. Manifest Functions There are several major manifest functions associated with education. The first is socialization. Beginning in preschool and kindergarten, students are taught to practice various societal roles. The French sociologist Émile Durkheim (1858–1917), who established the academic discipline of sociology, characterized schools as “socialization agencies that teach children how to get along with others and prepare them for adult economic roles” (Durkheim 1898). Indeed, it seems that schools have taken on this responsibility in full. This socialization also involves learning the rules and norms of the society as a whole. In the early days of compulsory education, students learned the dominant culture. Today, since the culture of the United States is increasingly diverse, students may learn a variety of cultural norms, not only that of the dominant culture. School systems in the United States also transmit the core values of the nation through manifest functions like social control. One of the roles of schools is to teach students conformity to law and respect for authority. Obviously, such respect, given to teachers and administrators, will help a student navigate the school environment. This function also prepares students to enter the workplace and the world at large, where they will continue to be subject to people who have authority over them. Fulfillment of this function rests primarily with classroom teachers and instructors who are with students all day. Education also provides one of the major methods used by people for upward social mobility. This function is referred to as social placement . College and graduate schools are viewed as vehicles for moving students closer to the careers that will give them the financial freedom and security they seek. As a result, college students are often more motivated to study areas that they believe will be advantageous on the social ladder. A student might value business courses over a class in Victorian poetry because she sees business class as a stronger vehicle for financial success. Latent Functions Education also fulfills latent functions. As you well know, much goes on in a school that has little to do with formal education. For example, you might notice an attractive fellow student when he gives a particularly interesting answer in class—catching up with him and making a date speaks to the latent function of courtship fulfilled by exposure to a peer group in the educational setting. The educational setting introduces students to social networks that might last for years and can help people find jobs after their schooling is complete. Of course, with social media such as Facebook and LinkedIn, these networks are easier than ever to maintain. Another latent function is the ability to work with others in small groups, a skill that is transferable to a workplace and that might not be learned in a homeschool setting. The educational system, especially as experienced on university campuses, has traditionally provided a place for students to learn about various social issues. There is ample opportunity for social and political advocacy, as well as the ability to develop tolerance to the many views represented on campus. In 2011, the Occupy Wall Street movement swept across college campuses all over the United States, leading to demonstrations in which diverse groups of students were unified with the purpose of changing the political climate of the country. Manifest Functions: Openly stated functions with intended goals Latent Functions: Hidden, unstated functions with sometimes unintended consequences Socialization Courtship Transmission of culture Social networks Social control Working in groups Social placement Creation of generation gap Cultural innovation Political and social integration Table 16.1 Manifest and Latent Functions of Education According to functionalist theory, education contributes both manifest and latent functions. Functionalists recognize other ways that schools educate and enculturate students. One of the most important American values students in the United States learn is that of individualism—the valuing of the individual over the value of groups or society as a whole. In countries such as Japan and China, where the good of the group is valued over the rights of the individual, students do not learn as they do in the United States that the highest rewards go to the “best” individual in academics as well as athletics. One of the roles of schools in the United States is fostering self-esteem; conversely, schools in Japan focus on fostering social esteem—the honoring of the group over the individual. In the United States, schools also fill the role of preparing students for competition in life. Obviously, athletics foster a competitive nature, but even in the classroom students compete against one another academically. Schools also fill the role of teaching patriotism. Students recite the Pledge of Allegiance each morning and take history classes where they learn about national heroes and the nation’s past. Another role of schools, according to functionalist theory, is that of sorting , or classifying students based on academic merit or potential. The most capable students are identified early in schools through testing and classroom achievements. Such students are placed in accelerated programs in anticipation of successful college attendance. Functionalists also contend that school, particularly in recent years, is taking over some of the functions that were traditionally undertaken by family. Society relies on schools to teach about human sexuality as well as basic skills such as budgeting and job applications—topics that at one time were addressed by the family. Conflict Theory Conflict theorists do not believe that public schools reduce social inequality. Rather, they believe that the educational system reinforces and perpetuates social inequalities arising from differences in class, gender, race, and ethnicity. Where functionalists see education as serving a beneficial role, conflict theorists view it more negatively. To them, educational systems preserve the status quo and push people of lower status into obedience. The fulfillment of one’s education is closely linked to social class. Students of low socioeconomic status are generally not afforded the same opportunities as students of higher status, no matter how great their academic ability or desire to learn. Picture a student from a working-class home who wants to do well in school. On a Monday, he’s assigned a paper that’s due Friday. Monday evening, he has to babysit his younger sister while his divorced mother works. Tuesday and Wednesday, he works stocking shelves after school until 10:00 p.m. By Thursday, the only day he might have available to work on that assignment, he’s so exhausted he can’t bring himself to start the paper. His mother, though she’d like to help him, is so tired herself that she isn’t able to give him the encouragement or support he needs. And since English is her second language, she has difficulty with some of his educational materials. They also lack a computer and printer at home, which most of his classmates have, so they have to rely on the public library or school system for access to technology. As this story shows, many students from working class families have to contend with helping out at home, contributing financially to the family, poor study environments and a lack of support from their families. This is a difficult match with education systems that adhere to a traditional curriculum that is more easily understood and completed by students of higher social classes. Such a situation leads to social class reproduction, extensively studied by French sociologist Pierre Bourdieu. He researched how cultural capital , or cultural knowledge that serves (metaphorically) as currency that helps one navigate a culture, alters the experiences and opportunities available to French students from different social classes. Members of the upper and middle classes have more cultural capital than do families of lower class status. As a result, the educational system maintains a cycle in which the dominant culture’s values are rewarded. Instruction and tests cater to the dominant culture and leave others struggling to identify with values and competencies outside their social class. For example, there has been a great deal of discussion over what standardized tests such as the SAT truly measure. Many argue that the tests group students by cultural ability rather than by natural intelligence. The cycle of rewarding those who possess cultural capital is found in formal educational curricula as well as in the hidden curriculum , which refers to the type of nonacademic knowledge that one learns through informal learning and cultural transmission. This hidden curriculum reinforces the positions of those with higher cultural capital, and serves to bestow status unequally. Conflict theorists point to tracking , a formalized sorting system that places students on “tracks” (advanced versus low achievers) that perpetuate inequalities. While educators may believe that students do better in tracked classes because they are with students of similar ability and may have access to more individual attention from teachers, conflict theorists feel that tracking leads to self-fulfilling prophecies in which students live up (or down) to teacher and societal expectations (Education Week 2004). To conflict theorists, schools play the role of training working class students to accept and retain their position as lower members of society. They argue that this role is fulfilled through the disparity of resources available to students in richer and poorer neighborhoods as well as through testing (Lauen and Tyson 2008). IQ tests have been attacked for being biased—for testing cultural knowledge rather than actual intelligence. For example, a test item may ask students what instruments belong in an orchestra. To correctly answer this question requires certain cultural knowledge—knowledge most often held by more affluent people who typically have more exposure to orchestral music. Though experts in testing claim that bias has been eliminated from tests, conflict theorists maintain that this is impossible. These tests, to conflict theorists, are another way in which education does not provide opportunities, but instead maintains an established configuration of power. Feminist Theory Feminist theory aims to understand the mechanisms and roots of gender inequality in education, as well as their societal repercussions. Like many other institutions of society, educational systems are characterized by unequal treatment and opportunity for women. Almost two-thirds of the world’s 862 million illiterate people are women, and the illiteracy rate among women is expected to increase in many regions, especially in several African and Asian countries (UNESCO 2005; World Bank 2007). Women in American have been relatively late, historically speaking, to be granted entry to the public university system. In fact, it wasn’t until the establishment of Title IX of the Education Amendments in 1972 that discriminating on the basis of sex in U.S. education programs became illegal. In the United States, there is also a post-education gender disparity between what male and female college graduates earn. A study released in May 2011 showed that, among men and women who graduated from college between 2006 and 2010, men out-earned women by an average of more than $5,000 each year. First year job earnings for men averaged $33,150; for women the average was $28,000 (Godofsky, Zukin, and van Horn 2011). Similar trends are seen among salaries of professionals in virtually all industries. When women face limited opportunities for education, their capacity to achieve equal rights, including financial independence, are limited. Feminist theory seeks to promote women’s rights to equal education (and its resultant benefits) across the world. Sociology in the Real World Grade Inflation: When Is an A Really a C? Consider a large-city newspaper publisher. Ten years ago, when culling résumés for an entry-level copywriter, they were well assured that if they selected a grad with a GPA of 3.7 or higher, they’d have someone with the writing skills to contribute to the workplace on day one. But over the last few years, they’ve noticed that A-level students don’t have the competency evident in the past. More and more, they find themselves in the position of educating new hires in abilities that, in the past, had been mastered during their education. This story illustrates a growing concern referred to as grade inflation —a term used to describe the observation that the correspondence between letter grades and the achievements they reflect has been changing (in a downward direction) over time. Put simply, what used to be considered C-level, or average, now often earns a student a B, or even an A. Why is this happening? Research on this emerging issue is ongoing, so no one is quite sure yet. Some cite the alleged shift toward a culture that rewards effort instead of product, i.e., the amount of work a student puts in raises the grade, even if the resulting product is poor quality. Another oft-cited contributor is the pressure many of today’s instructors feel to earn positive course evaluations from their students—records that can tie into teacher compensation, award of tenure, or the future career of a young grad teaching entry-level courses. The fact that these reviews are commonly posted online exacerbates this pressure. Other studies don’t agree that grade inflation exists at all. In any case, the issue is hotly debated, with many being called upon to conduct research to help us better understand and respond to this trend (National Public Radio 2004; Mansfield 2005). Symbolic Interactionism Symbolic interactionism sees education as one way labeling theory is seen in action. A symbolic interactionist might say that this labeling has a direct correlation to those who are in power and those who are being labeled. For example, low standardized test scores or poor performance in a particular class often lead to a student being labeled as a low achiever. Such labels are difficult to “shake off,” which can create a self-fulfilling prophecy (Merton 1968). In his book High School Confidential , Jeremy Iverson details his experience as a Stanford graduate posing as a student at a California high school. One of the problems he identifies in his research is that of teachers applying labels that students are never able to lose. One teacher told him, without knowing he was a bright graduate of a top university, that he would never amount to anything (Iverson 2006). Iverson obviously didn’t take this teacher’s false assessment to heart. But when an actual 17-year-old student hears this from a person with authority over her, it’s no wonder that the student might begin to “live down to” that label. The labeling with which symbolic interactionists concern themselves extends to the very degrees that symbolize completion of education. Credentialism embodies the emphasis on certificates or degrees to show that a person has a certain skill, has attained a certain level of education, or has met certain job qualifications. These certificates or degrees serve as a symbol of what a person has achieved, allowing the labeling of that individual. Indeed, as these examples show, labeling theory can significantly impact a student’s schooling. This is easily seen in the educational setting, as teachers and more powerful social groups within the school dole out labels that are adopted by the entire school population. 16.3 Issues in Education As schools strive to fill a variety of roles in their students’ lives, many issues and challenges arise. Students walk a minefield of bullying, violence in schools, the results of declining funding, plus other problems that affect their education. When Americans are asked about their opinion of public education on the Gallup poll each year, reviews are mixed at best (Saad 2008). Schools are no longer merely a place for learning and socializing. With the landmark Brown v. Board of Education of Topeka ruling in 1954, schools became a repository of much political and legal action that is at the heart of several issues in education. Equal Education Until the 1954 Brown v. Board of Education ruling, schools had operated under the precedent set by Plessy v. Ferguson in 1896, which allowed racial segregation in schools and private businesses (the case dealt specifically with railroads) and introduced the much maligned phrase “separate but equal” into the United States lexicon. The 1954 Brown v. Board decision overruled this, declaring that state laws that had established separate schools for black and white students were, in fact, unequal and unconstitutional. While the ruling paved the way toward civil rights, it was also met with contention in many communities. In Arkansas in 1957, the governor mobilized the state National Guard to prevent black students from entering Little Rock Central High School. President Eisenhower, in response, sent members of the 101st Airborne Division from Kentucky to uphold the students’ right to enter the school. In 1963, almost ten years after the ruling, Governor George Wallace of Alabama used his own body to block two black students from entering the auditorium at the University of Alabama to enroll in the school. Wallace’s desperate attempt to uphold his policy of “segregation now, segregation tomorrow, segregation forever,” stated during his 1963 inauguration (PBS 2000) became known as the “Stand in the Schoolhouse Door.” He refused to grant entry to the students until a general from the Alabama National Guard arrived on President Kennedy’s order. Presently, students of all races and ethnicities are permitted into schools, but there remains a troubling gap in the equality of education they receive. The long-term socially embedded effects of racism—and other discrimination and disadvantage—have left a residual mark of inequality in the nation’s education system. Students from wealthy families and those of lower socioeconomic status do not receive the same opportunities. Today’s public schools, at least in theory, are positioned to help remedy those gaps. Predicated on the notion of universal access, this system is mandated to accept and retain all students regardless of race, religion, social class, and the like. Moreover, public schools are held accountable to equitable per-student spending (Resnick 2004). Private schools, usually only accessible to students from high-income families, and schools in more affluent areas generally enjoy access to greater resources and better opportunities. In fact, some of the key predictors for student performance include socioeconomic status and family background. Children from families of lower socioeconomic status often enter school with learning deficits they struggle to overcome throughout their educational tenure. These patterns, uncovered in the landmark Coleman Report of 1966, are still highly relevant today, as sociologists still generally agree that there is a great divide in the performance of white students from affluent backgrounds and their non-white, less affluent, counterparts (Coleman 1966). Head Start The findings in the Coleman Report were so powerful that they brought about two major changes to education in the United States. The federal Head Start program , which is still active and successful today, was developed to give low-income students an opportunity to make up the pre-school deficit discussed in Coleman’s findings. The program provides academic-centered preschool to students of low socioeconomic status. Busing The second major change brought about after the release of the Coleman Report was less successful than the Head Start program and has been the subject of a great deal of controversy. With the goal of further desegregating education, courts across the United States ordered some school districts to begin a program that became known as “busing.” This program involved bringing students to schools outside their neighborhoods (and therefore schools they would not normally have the opportunity to attend) to bring racial diversity into balance. This practice was met with a great deal of public resistance from people on both sides dissatisfied with white students traveling to inner city schools and minority students bring transported to schools in the suburbs. No Child Left Behind In 2001, the Bush administration passed the No Child Left Behind Act , which requires states to test students in designated grades. The results of those tests determine eligibility to receive federal funding. Schools that do not meet the standards set by the Act run the risk of having their funding cut. Sociologists and teachers alike have contended that the impact of the No Child Left Behind Act is far more negative than positive, arguing that a “one size fits all” concept cannot apply to education. Teaching to the Test The funding tie-in of the No Child Left Behind Act has led to the social phenomenon commonly called “teaching to the test,” which describes when a curriculum focuses on equipping students to succeed on standardized tests, to the detriment of broader educational goals and concepts of learning. At issue are two approaches to classroom education: the notion that teachers impart knowledge that students are obligated to absorb, versus the concept of student-centered learning that seeks to teach children not facts, but problem solving abilities and learning skills. Both types of learning have been valued in the American school system. The former, to critics of “teaching to the test,” only equips students to regurgitate facts, while the latter, to proponents of the other camp, fosters lifelong learning and transferable work skills. Bilingual Education New issues of inequality have entered the national conversation in recent years with the issue of bilingual education, which attempts to give equal opportunity to minority students through offering instruction in languages other than English. Though it is actually an old issue (bilingual education was federally mandated in 1968), it remains one of hot debate. Supporters of bilingual education argue that all students deserve equal opportunities in education—opportunities some students cannot access without instruction in their first language. On the other side, those who oppose bilingual education often point to the need for English fluency in everyday life and in the professional world. Charter Schools Charter schools are self-governing public schools that have signed agreements with state governments to improve students when poor performance is revealed on tests required by the No Child Left Behind Act. While such schools receive public money, they are not subject to the same rules that apply to regular public schools. In return, they make agreements to achieve specific results. Charter schools, as part of the public education system, are free to attend, and are accessible via lottery when there are more students seeking enrollment than there are spots available at the school. Some charter schools specialize in certain fields, such as the arts or science, while others are more generalized. Sociology in the Real World Money as Motivation in Charter Schools Public school teachers typically find stability, comprehensive benefits packages, and long-term job security. In 2011, one charter school in New York City set out to learn if teachers would give up those protections if it meant an opportunity to make much more money than the typical teacher’s salary. The Equity Project is a privately run charter school that offered teachers positions paying $125,000 per year (more than twice the average salary for teachers). The school’s founder and principal, Zeke Vanderhoek, explained that this allows him to attract the best and brightest teachers to his school—to decide whom he hires and how much they are paid—and build a school where “every teacher is a great teacher” (CBS News 2011). He sees attracting top teachers as a direct road to student achievement. A nationwide talent search resulted in the submission of thousands of applications. The final round of interviews consisted of a day-long trial run. The school looks for teachers who can show evidence of student growth and achievement. They also must be highly engaging. The majority of students at the school are African American and Hispanic, from poor families, and reading below grade level. The school faces the challenge faced by schools all over the United States: getting poor, disadvantaged students to perform at the same level as their more affluent counterparts. Vanderhoek believes his team of dream teachers can help students close their learning gaps by several grade levels within one year. This is not an affluent school. It is publicly funded and classes are held in trailers. Most of the school’s budget goes into the teachers’ salaries. There are no reading or math aides; those roles are filled by the regular classroom teachers. The experiment may be working. Students who were asked how they feel about their education at The Equity Project said that their teachers care if they succeed and give them the attention they need to achieve at high levels. They cite the feeling that their teachers believe in them as a major reason for liking school for the first time. Of course, with the high salary comes high risk. Most public schools offer contracts to teachers. Those contracts guarantee job security. But The Equity Project is an at-will employer. Those who don’t meet the standards set by the school will lose their jobs. Vanderhoek does not believe in teacher tenure, which he feels gives teachers “a job for life no matter how they perform” (CBS News 2011). With a teaching staff of roughly 15, he terminated two teachers after the first year. In comparison, in New York City as a whole, only seven teachers out of 55,000 with tenure have been terminated for poor performance. One of those two teachers who was let go said she was relieved, citing 80- to 90-hour work weeks and a decline in the quality of her family life. Meanwhile, there is some question as to whether the model is working. On one hand, there are individual success stories, such as a student whose reading skills increased two grade levels in a single year. On the other, there is the fact that on the state math and reading exams taken by all fifth graders, the Equity Project students remained out-scored by other district schools (CBS News 2011). Teacher Training Schools face an issue of teacher effectiveness, in that most high school teachers perceive students as being prepared for college, while most college professors do not see those same students as prepared for the rigors of collegiate study. Some feel that this is due to teachers being unprepared to teach. Many teachers in the United States teach subject matter that is outside their own field of study. This is not the case in many European and Asian countries. Only eight percent of United States fourth-grade math teachers majored or minored in math, compared with 48 percent in Singapore. Further, students in disadvantaged American schools are 77 percent more likely to be educated by a teacher who didn’t specialize in the subject matter than students who attend schools in affluent neighborhoods (Holt, McGrath, and Seastrom 2006). Social Promotion Social promotion is another issue identified by sociologists. This is the concept of passing students to the next grade regardless of their meeting standards for that grade. Critics of this practice argue that students should never move to the next grade if they have not mastered the skills required to “graduate” from the previous grade. Proponents of the practice question what a school is to do with a student who is three to four years older than other students in his or her grade, saying this creates more issues than the practice of social promotion. Affirmative Action Affirmative action has been a subject of debate, primarily as it relates to the admittance of college students. Opponents suggest that, under affirmative action, minority students are given greater weighted priorities for admittance. Supporters of affirmative action point to the way in which it grants opportunities to students who are traditionally done a disservice in the college admission process. Rising Student Loan Debt In a growing concern, the amount of college loan debt that students are taking on is creating a new social challenge. As of 2010, the debts of students with student loans averaged $25,250 upon graduation, leaving students hard-pressed to repay their education while earning entry-level wages, even at the professional level (Lewin 2011). With the increase in unemployment since the 2008 recession, jobs are scarce, making this burden more pronounced. As recent grads find themselves unable to meet their financial obligations, all of society is affected. Home Schooling Homeschooling refers to children being educated in their own homes, typically by a parent, instead of in a traditional public or private school system. Proponents of this type of education argue that it provides an outstanding opportunity for student-centered learning while circumventing problems that plague today’s education system. Opponents counter that homeschooled children miss out on the opportunity for social development that occurs in standard classroom environments and school settings. Proponents say that parents know their own children better than anyone else and are thus best equipped to teach them. Those on the other side of the debate assert that childhood education is a complex task and requires the degree teachers spend four years earning. After all, they argue, a parent may know her child’s body better than anyone, yet she seeks out a doctor for her child’s medical treatment. Just as a doctor is a trained medical expert, teachers are trained education experts. The National Center for Education Statistics shows that the quality of the national education system isn’t the only major concern of homeschoolers. While nearly half cite their reason for homeschooling as the belief that they can give their child a better education than the school system can, just under 40 percent choose homeschooling for “religious reasons” (NCES 2008). To date, researchers have not found consensus in studies evaluating the success, or lack thereof, of homeschooling.
microbiology
Summary 1.1 What Our Ancestors Knew Microorganisms (or microbes ) are living organisms that are generally too small to be seen without a microscope. Throughout history, humans have used microbes to make fermented foods such as beer, bread, cheese, and wine. Long before the invention of the microscope, some people theorized that infection and disease were spread by living things that were too small to be seen. They also correctly intuited certain principles regarding the spread of disease and immunity. Antonie van Leeuwenhoek, using a microscope, was the first to actually describe observations of bacteria, in 1675. During the Golden Age of Microbiology (1857–1914), microbiologists, including Louis Pasteur and Robert Koch, discovered many new connections between the fields of microbiology and medicine. 1.2 A Systematic Approach Carolus Linnaeus developed a taxonomic system for categorizing organisms into related groups. Binomial nomenclature assigns organisms Latinized scientific names with a genus and species designation. A phylogenetic tree is a way of showing how different organisms are thought to be related to one another from an evolutionary standpoint. The first phylogenetic tree contained kingdoms for plants and animals; Ernst Haeckel proposed adding kingdom for protists. Robert Whittaker’s tree contained five kingdoms: Animalia, Plantae, Protista, Fungi, and Monera. Carl Woese used small subunit ribosomal RNA to create a phylogenetic tree that groups organisms into three domains based on their genetic similarity. Bergey’s manuals of determinative and systemic bacteriology are the standard references for identifying and classifying bacteria, respectively. Bacteria can be identified through biochemical tests, DNA/RNA analysis, and serological testing methods. 1.3 Types of Microorganisms Microorganisms are very diverse and are found in all three domains of life: Archaea, Bacteria, and Eukarya. Archaea and bacteria are classified as prokaryotes because they lack a cellular nucleus. Archaea differ from bacteria in evolutionary history, genetics, metabolic pathways, and cell wall and membrane composition. Archaea inhabit nearly every environment on earth, but no archaea have been identified as human pathogens. Eukaryotes studied in microbiology include algae, protozoa, fungi, and helminths. Algae are plant-like organisms that can be either unicellular or multicellular, and derive energy via photosynthesis. Protozoa are unicellular organisms with complex cell structures; most are motile. Microscopic fungi include molds and yeasts . Helminths are multicellular parasitic worms. They are included in the field of microbiology because their eggs and larvae are often microscopic. Viruses are acellular microorganisms that require a host to reproduce. The field of microbiology is extremely broad. Microbiologists typically specialize in one of many subfields, but all health professionals need a solid foundation in clinical microbiology.
Chapter Outline 1.1 What Our Ancestors Knew 1.2 A Systematic Approach 1.3 Types of Microorganisms Introduction From boiling thermal hot springs to deep beneath the Antarctic ice, microorganisms can be found almost everywhere on earth in great quantities. Microorganisms (or microbes, as they are also called) are small organisms. Most are so small that they cannot be seen without a microscope. Most microorganisms are harmless to humans and, in fact, many are helpful. They play fundamental roles in ecosystems everywhere on earth, forming the backbone of many food webs. People use them to make biofuels, medicines, and even foods. Without microbes, there would be no bread, cheese, or beer. Our bodies are filled with microbes, and our skin alone is home to trillions of them. 1 Some of them we can’t live without; others cause diseases that can make us sick or even kill us. 1 J. Hulcr et al. “A Jungle in There: Bacteria in Belly Buttons are Highly Diverse, but Predictable.” PLoS ONE 7 no. 11 (2012): e47712. doi:10.1371/journal.pone.0047712. Although much more is known today about microbial life than ever before, the vast majority of this invisible world remains unexplored. Microbiologists continue to identify new ways that microbes benefit and threaten humans.
[ { "answer": { "ans_choice": 3, "ans_text": "D" }, "bloom": null, "hl_context": "Production of these foods and beverages requires microbial fermentation , a process that uses bacteria , mold , or yeast to convert sugars ( carbohydrates ) to alcohol , gases , and organic acids ( Figure 1.3 ) . <hl> While it is likely that people first learned about fermentation by accident — perhaps by drinking old milk that had curdled or old grape juice that had fermented — they later learned to harness the power of fermentation to make products like bread , cheese , and wine . <hl> <hl> People across the world have enjoyed fermented foods and beverages like beer , wine , bread , yogurt , cheese , and pickled vegetables for all of recorded history . <hl> Discoveries from several archeological sites suggest that even prehistoric people took advantage of fermentation to preserve and enhance the taste of food . Archaeologists studying pottery jars from a Neolithic village in China found that people were making a fermented beverage from rice , honey , and fruit as early as 7000 BC . 3 3 P . E . McGovern et al . “ Fermented Beverages of Pre - and Proto-Historic China . ” Proceedings of the National Academy of Sciences of the United States of America 1 no . 51 ( 2004 ): 17593 – 17598 . doi : 10.1073 / pnas . 04079211 02 .", "hl_sentences": "While it is likely that people first learned about fermentation by accident — perhaps by drinking old milk that had curdled or old grape juice that had fermented — they later learned to harness the power of fermentation to make products like bread , cheese , and wine . People across the world have enjoyed fermented foods and beverages like beer , wine , bread , yogurt , cheese , and pickled vegetables for all of recorded history .", "question": { "cloze_format": "The food that is NOT made by fermentation is ___ .", "normal_format": "Which of the following foods is NOT made by fermentation?", "question_choices": [ "beer", "bread", "cheese", "orange juice" ], "question_id": "fs-id1171360295368", "question_text": "Which of the following foods is NOT made by fermentation?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 3, "ans_text": "D" }, "bloom": null, "hl_context": "<hl> While Hippocrates is considered the father of Western medicine , the Greek philosopher and historian Thucydides ( 460 – 395 BC ) is considered the father of scientific history because he advocated for evidence-based analysis of cause-and-effect reasoning ( Figure 1.5 ) . <hl> Among his most important contributions are his observations regarding the Athenian plague that killed one-third of the population of Athens between 430 and 410 BC . Having survived the epidemic himself , Thucydides made the important observation that survivors did not get re-infected with the disease , even when taking care of actively sick people . 8 This observation shows an early understanding of the concept of immunity . 8 Thucydides . The History of the Peloponnesian War . The Second Book . 431 BC . Translated by Richard Crawley . http://classics.mit.edu/Thucydides/pelopwar.2.second.html . <hl> The Greek physician Hippocrates ( 460 – 370 BC ) is considered the “ father of Western medicine ” ( Figure 1.5 ) . <hl> Unlike many of his ancestors and contemporaries , he dismissed the idea that disease was caused by supernatural forces . Instead , he posited that diseases had natural causes from within patients or their environments . Hippocrates and his heirs are believed to have written the Hippocratic Corpus , a collection of texts that make up some of the oldest surviving medical books . 7 Hippocrates is also often credited as the author of the Hippocratic Oath , taken by new physicians to pledge their dedication to diagnosing and treating patients without causing harm . 7 G . Pappas et al . “ Insights Into Infectious Disease in the Era of Hippocrates . ” International Journal of Infectious Diseases 12 ( 2008 ) 4:347 – 350 . doi : http://dx.doi.org/10.1016/j.ijid.2007.11.003 .", "hl_sentences": "While Hippocrates is considered the father of Western medicine , the Greek philosopher and historian Thucydides ( 460 – 395 BC ) is considered the father of scientific history because he advocated for evidence-based analysis of cause-and-effect reasoning ( Figure 1.5 ) . The Greek physician Hippocrates ( 460 – 370 BC ) is considered the “ father of Western medicine ” ( Figure 1.5 ) .", "question": { "cloze_format": "The “father of Western medicine” is considered ___.", "normal_format": "Who is considered the “father of Western medicine”?", "question_choices": [ "Marcus Terentius Varro", "Thucydides", "Antonie van Leeuwenhoek", "Hippocrates" ], "question_id": "fs-id1171360229175", "question_text": "Who is considered the “father of Western medicine”?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 0, "ans_text": "A" }, "bloom": null, "hl_context": "While the ancients may have suspected the existence of invisible “ minute creatures , ” it wasn ’ t until the invention of the microscope that their existence was definitively confirmed . <hl> While it is unclear who exactly invented the microscope , a Dutch cloth merchant named Antonie van Leeuwenhoek ( 1632 – 1723 ) was the first to develop a lens powerful enough to view microbes . <hl> <hl> In 1675 , using a simple but powerful microscope , Leeuwenhoek was able to observe single-celled organisms , which he described as “ animalcules ” or “ wee little beasties , ” swimming in a drop of rain water . <hl> From his drawings of these little organisms , we now know he was looking at bacteria and protists . ( We will explore Leeuwenhoek ’ s contributions to microscopy further in How We See the Invisible World . )", "hl_sentences": "While it is unclear who exactly invented the microscope , a Dutch cloth merchant named Antonie van Leeuwenhoek ( 1632 – 1723 ) was the first to develop a lens powerful enough to view microbes . In 1675 , using a simple but powerful microscope , Leeuwenhoek was able to observe single-celled organisms , which he described as “ animalcules ” or “ wee little beasties , ” swimming in a drop of rain water .", "question": { "cloze_format": "The first to observe “animalcules” under the microscope was ___.", "normal_format": "Who was the first to observe “animalcules” under the microscope?", "question_choices": [ "Antonie van Leeuwenhoek", "Ötzi the Iceman", "Marcus Terentius Varro", "Robert Koch" ], "question_id": "fs-id1171359008696", "question_text": "Who was the first to observe “animalcules” under the microscope?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 1, "ans_text": "B" }, "bloom": null, "hl_context": "<hl> Marcus Terentius Varro ( 116 – 27 BC ) was a prolific Roman writer who was one of the first people to propose the concept that things we cannot see ( what we now call microorganisms ) can cause disease ( Figure 1.5 ) . <hl> <hl> In Res Rusticae ( On Farming ) , published in 36 BC , he said that “ precautions must also be taken in neighborhood swamps . <hl> . . because certain minute creatures [ animalia minuta ] grow there which cannot be seen by the eye , which float in the air and enter the body through the mouth and nose and there cause serious diseases . ” 9 9 Plinio Prioreschi . A History of Medicine : Roman Medicine . Lewiston , NY : Edwin Mellen Press , 1998 : p . 215 .", "hl_sentences": "Marcus Terentius Varro ( 116 – 27 BC ) was a prolific Roman writer who was one of the first people to propose the concept that things we cannot see ( what we now call microorganisms ) can cause disease ( Figure 1.5 ) . In Res Rusticae ( On Farming ) , published in 36 BC , he said that “ precautions must also be taken in neighborhood swamps .", "question": { "cloze_format": "The person who proposed that swamps might harbor tiny, disease-causing animals too small to see was ___.", "normal_format": "Who proposed that swamps might harbor tiny, disease-causing animals too small to see?", "question_choices": [ "Thucydides", "Marcus Terentius Varro", "Hippocrates", "Louis Pasteur" ], "question_id": "fs-id1171359210036", "question_text": "Who proposed that swamps might harbor tiny, disease-causing animals too small to see?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 2, "ans_text": "C" }, "bloom": null, "hl_context": "<hl> Linnaeus ’ s tree of life contained just two main branches for all living things : the animal and plant kingdoms . <hl> In 1866 , Ernst Haeckel , a German biologist , philosopher , and physician , proposed another kingdom , Protista , for unicellular organisms ( Figure 1.9 ) . He later proposed a fourth kingdom , Monera , for unicellular organisms whose cells lack nuclei , like bacteria . <hl> In his taxonomy , Linnaeus divided the natural world into three kingdoms : animal , plant , and mineral ( the mineral kingdom was later abandoned ) . <hl> Within the animal and plant kingdoms , he grouped organisms using a hierarchy of increasingly specific levels and sublevels based on their similarities . The names of the levels in Linnaeus ’ s original taxonomy were kingdom , class , order , family , genus ( plural : genera ) , and species . Species was , and continues to be , the most specific and basic taxonomic unit .", "hl_sentences": "Linnaeus ’ s tree of life contained just two main branches for all living things : the animal and plant kingdoms . In his taxonomy , Linnaeus divided the natural world into three kingdoms : animal , plant , and mineral ( the mineral kingdom was later abandoned ) .", "question": { "cloze_format": "A/ an ___ was NOT a kingdom in Linnaeus’s taxonomy.", "normal_format": "Which of the following was NOT a kingdom in Linnaeus’s taxonomy?", "question_choices": [ "animal", "mineral", "protist", "plant" ], "question_id": "fs-id1171360344461", "question_text": "Which of the following was NOT a kingdom in Linnaeus’s taxonomy?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 2, "ans_text": "C" }, "bloom": null, "hl_context": "In developing his taxonomy , Linnaeus used a system of binomial nomenclature , a two-word naming system for identifying organisms by genus and specific epithet . <hl> For example , modern humans are in the genus Homo and have the specific epithet name sapiens , so their scientific name in binomial nomenclature is Homo sapiens . <hl> In binomial nomenclature , the genus part of the name is always capitalized ; it is followed by the specific epithet name , which is not capitalized . Both names are italicized . <hl> When referring to the species of humans , the binomial nomenclature would be Homo sapiens . <hl> Taxonomic names in the 18th through 20th centuries were typically derived from Latin , since that was the common language used by scientists when taxonomic systems were first created . Today , newly discovered organisms can be given names derived from Latin , Greek , or English . Sometimes these names reflect some distinctive trait of the organism ; in other cases , microorganisms are named after the scientists who discovered them . The archaeon Haloquadratum walsbyi is an example of both of these naming schemes . The genus , Haloquadratum , describes the microorganism ’ s saltwater habitat ( halo is derived from the Greek word for “ salt ” ) as well as the arrangement of its square cells , which are arranged in square clusters of four cells ( quadratum is Latin for “ foursquare ” ) . The species , walsbyi , is named after Anthony Edward Walsby , the microbiologist who discovered Haloquadratum walsbyi in in 1980 . While it might seem easier to give an organism a common descriptive name — like a red-headed woodpecker — we can imagine how that could become problematic . What happens when another species of woodpecker with red head coloring is discovered ? The systematic nomenclature scientists use eliminates this potential problem by assigning each organism a single , unique two-word name that is recognized by scientists all over the world .", "hl_sentences": "For example , modern humans are in the genus Homo and have the specific epithet name sapiens , so their scientific name in binomial nomenclature is Homo sapiens . When referring to the species of humans , the binomial nomenclature would be Homo sapiens .", "question": { "cloze_format": "___ is a correct usage of binomial nomenclature.", "normal_format": "Which of the following is a correct usage of binomial nomenclature?", "question_choices": [ "Homo Sapiens", "homo sapiens", "Homo sapiens", "Homo Sapiens" ], "question_id": "fs-id1171360530144", "question_text": "Which of the following is a correct usage of binomial nomenclature?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 3, "ans_text": "D" }, "bloom": null, "hl_context": "Linnaeus ’ s tree of life contained just two main branches for all living things : the animal and plant kingdoms . <hl> In 1866 , Ernst Haeckel , a German biologist , philosopher , and physician , proposed another kingdom , Protista , for unicellular organisms ( Figure 1.9 ) . <hl> He later proposed a fourth kingdom , Monera , for unicellular organisms whose cells lack nuclei , like bacteria .", "hl_sentences": "In 1866 , Ernst Haeckel , a German biologist , philosopher , and physician , proposed another kingdom , Protista , for unicellular organisms ( Figure 1.9 ) .", "question": { "cloze_format": "The scientist that proposed adding a kingdom for protists was ___.", "normal_format": "Which scientist proposed adding a kingdom for protists?", "question_choices": [ "Carolus Linnaeus", "Carl Woese", "Robert Whittaker", "Ernst Haeckel" ], "question_id": "fs-id1171360274356", "question_text": "Which scientist proposed adding a kingdom for protists?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 0, "ans_text": "A" }, "bloom": null, "hl_context": "<hl> Microorganisms are found in each of the three domains of life : Archaea , Bacteria , and Eukarya . <hl> Microbes within the domains Bacteria and Archaea are all prokaryotes ( their cells lack a nucleus ) , whereas microbes in the domain Eukarya are eukaryotes ( their cells have a nucleus ) . Some microorganisms , such as viruses , do not fall within any of the three domains of life . In this section , we will briefly introduce each of the broad groups of microbes . Later chapters will go into greater depth about the diverse species within each group . <hl> In the 1970s , American microbiologist Carl Woese discovered what appeared to be a “ living record ” of the evolution of organisms . <hl> <hl> He and his collaborator George Fox created a genetics-based tree of life based on similarities and differences they observed in the gene sequences coding for small subunit ribosomal RNA ( rRNA ) of different organisms . <hl> In the process , they discovered that a certain type of bacteria , called archaebacteria ( now known simply as archaea ) , were significantly different from other bacteria and eukaryotes in terms of their small subunit rRNA gene sequences . <hl> To accommodate this difference , they created a tree with three Domains above the level of Kingdom : Archaea , Bacteria , and Eukarya ( Figure 1.11 ) . <hl> Analysis of small subunit rRNA gene sequences suggests archaea , bacteria , and eukaryotes all evolved from a common ancestral cell type . The tree is skewed to show a closer evolutionary relationship between Archaea and Eukarya than they have to Bacteria .", "hl_sentences": "Microorganisms are found in each of the three domains of life : Archaea , Bacteria , and Eukarya . In the 1970s , American microbiologist Carl Woese discovered what appeared to be a “ living record ” of the evolution of organisms . He and his collaborator George Fox created a genetics-based tree of life based on similarities and differences they observed in the gene sequences coding for small subunit ribosomal RNA ( rRNA ) of different organisms . To accommodate this difference , they created a tree with three Domains above the level of Kingdom : Archaea , Bacteria , and Eukarya ( Figure 1.11 ) .", "question": { "cloze_format": "___ is/are NOT a domain in Woese and Fox’s phylogenetic tree.", "normal_format": "Which of the following is NOT a domain in Woese and Fox’s phylogenetic tree?", "question_choices": [ "Plantae", "Bacteria", "Archaea", "Eukarya" ], "question_id": "fs-id1171360367608", "question_text": "Which of the following is NOT a domain in Woese and Fox’s phylogenetic tree?" }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 1, "ans_text": "B" }, "bloom": null, "hl_context": "Whether in a tree or a web , microbes can be difficult to identify and classify . Without easily observable macroscopic features like feathers , feet , or fur , scientists must capture , grow , and devise ways to study their biochemical properties to differentiate and classify microbes . Despite these hurdles , a group of microbiologists created and updated a set of manuals for identifying and classifying microorganisms . <hl> First published in 1923 and since updated many times , Bergey ’ s Manual of Determinative Bacteriology and Bergey ’ s Manual of Systematic Bacteriology are the standard references for identifying and classifying different prokaryotes . <hl> ( Appendix D of this textbook is partly based on Bergey ’ s manuals ; it shows how the organisms that appear in this textbook are classified . ) <hl> Because so many bacteria look identical , methods based on nonvisual characteristics must be used to identify them . <hl> For example , biochemical tests can be used to identify chemicals unique to certain species . Likewise , serological tests can be used to identify specific antibodies that will react against the proteins found in certain species . Ultimately , DNA and rRNA sequencing can be used both for identifying a particular bacterial species and for classifying newly discovered species .", "hl_sentences": "First published in 1923 and since updated many times , Bergey ’ s Manual of Determinative Bacteriology and Bergey ’ s Manual of Systematic Bacteriology are the standard references for identifying and classifying different prokaryotes . Because so many bacteria look identical , methods based on nonvisual characteristics must be used to identify them .", "question": { "cloze_format": "___ is the standard resource for identifying bacteria.", "normal_format": "Which of the following is the standard resource for identifying bacteria?", "question_choices": [ "Systema Naturae", "Bergey’s Manual of Determinative Bacteriology", "Woese and Fox’s phylogenetic tree", "Haeckel’s General Morphology of Organisms" ], "question_id": "fs-id1171360353040", "question_text": "Which of the following is the standard resource for identifying bacteria?" }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 3, "ans_text": "D" }, "bloom": null, "hl_context": "Protist s are an informal grouping of eukaryotes that are not plants , animals , or fungi . Algae and protozoa are examples of protists . Algae ( singular : alga ) are protists that can be either unicellular or multicellular and vary widely in size , appearance , and habitat ( Figure 1.15 ) . Their cells are surrounded by cell walls made of cellulose , a type of carbohydrate . <hl> Algae are photosynthetic organisms that extract energy from the sun and release oxygen and carbohydrates into their environment . <hl> Because other organisms can use their waste products for energy , algae are important parts of many ecosystems . Many consumer products contain ingredients derived from algae , such as carrageenan or alginic acid , which are found in some brands of ice cream , salad dressing , beverages , lipstick , and toothpaste . A derivative of algae also plays a prominent role in the microbiology laboratory . Agar , a gel derived from algae , can be mixed with various nutrients and used to grow microorganisms in a Petri dish . Algae are also being developed as a possible source for biofuels .", "hl_sentences": "Algae are photosynthetic organisms that extract energy from the sun and release oxygen and carbohydrates into their environment .", "question": { "cloze_format": "___ is a microorganism that is photosynthetic.", "normal_format": "Which of the following types of microorganisms is photosynthetic?", "question_choices": [ "yeast", "virus", "helminth", "alga" ], "question_id": "fs-id1171360143106", "question_text": "Which of the following types of microorganisms is photosynthetic?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 2, "ans_text": "C" }, "bloom": null, "hl_context": "They have a wide range of metabolic capabilities and can grow in a variety of environments , using different combinations of nutrients . <hl> Some bacteria are photosynthetic , such as oxygenic cyanobacteria and anoxygenic green sulfur and green nonsulfur bacteria ; these bacteria use energy derived from sunlight , and fix carbon dioxide for growth . <hl> Other types of bacteria are nonphotosynthetic , obtaining their energy from organic or inorganic compounds in their environment . Bacteria are found in nearly every habitat on earth , including within and on humans . Most bacteria are harmless or helpful , but some are pathogen s , causing disease in humans and other animals . <hl> Bacteria are prokaryotic because their genetic material ( DNA ) is not housed within a true nucleus . <hl> Most bacteria have cell walls that contain peptidoglycan .", "hl_sentences": "Some bacteria are photosynthetic , such as oxygenic cyanobacteria and anoxygenic green sulfur and green nonsulfur bacteria ; these bacteria use energy derived from sunlight , and fix carbon dioxide for growth . Bacteria are prokaryotic because their genetic material ( DNA ) is not housed within a true nucleus .", "question": { "cloze_format": "___ is a prokaryotic microorganism.", "normal_format": "Which of the following is a prokaryotic microorganism?", "question_choices": [ "helminth", "protozoan", "cyanobacterium", "mold" ], "question_id": "fs-id1171360369592", "question_text": "Which of the following is a prokaryotic microorganism?" }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 0, "ans_text": "A" }, "bloom": null, "hl_context": "CJD is an extremely rare disease , with only about 300 cases in the United States each year . It is not caused by a bacterium , fungus , or virus , but rather by prions — which do not fit neatly into any particular category of microbe . <hl> Like viruses , prions are not found on the tree of life because they are acellular . <hl> Prions are extremely small , about one-tenth the size of a typical virus . They contain no genetic material and are composed solely of a type of abnormal protein . <hl> Virus es are acellular microorganisms , which means they are not composed of cells . <hl> Essentially , a virus consists of proteins and genetic material — either DNA or RNA , but never both — that are inert outside of a host organism . However , by incorporating themselves into a host cell , viruses are able to co-opt the host ’ s cellular mechanisms to multiply and infect other hosts .", "hl_sentences": "Like viruses , prions are not found on the tree of life because they are acellular . Virus es are acellular microorganisms , which means they are not composed of cells .", "question": { "cloze_format": "A ___ is acellular.", "normal_format": "Which of the following is acellular?", "question_choices": [ "virus", "bacterium", "fungus", "protozoan" ], "question_id": "fs-id1171360401236", "question_text": "Which of the following is acellular?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 3, "ans_text": "D" }, "bloom": null, "hl_context": "<hl> Unicellular fungi — yeasts — are included within the study of microbiology . <hl> There are more than 1000 known species . Yeasts are found in many different environments , from the deep sea to the human navel . Some yeasts have beneficial uses , such as causing bread to rise and beverages to ferment ; but yeasts can also cause food to spoil . Some even cause diseases , such as vaginal yeast infections and oral thrush ( Figure 1.17 ) . Growth media are used to grow microorganisms in a lab setting . Some media are liquids ; others are more solid or gel-like . <hl> A growth medium provides nutrients , including water , various salts , a source of carbon ( like glucose ) , and a source of nitrogen and amino acids ( like yeast extract ) so microorganisms can grow and reproduce . <hl> Ingredients in a growth medium can be modified to grow unique types of microorganisms .", "hl_sentences": "Unicellular fungi — yeasts — are included within the study of microbiology . A growth medium provides nutrients , including water , various salts , a source of carbon ( like glucose ) , and a source of nitrogen and amino acids ( like yeast extract ) so microorganisms can grow and reproduce .", "question": { "cloze_format": "___ is a type of fungal microorganism.", "normal_format": "Which of the following is a type of fungal microorganism?", "question_choices": [ "bacterium", "protozoan", "alga", "yeast" ], "question_id": "fs-id1171360258301", "question_text": "Which of the following is a type of fungal microorganism?" }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 1, "ans_text": "B" }, "bloom": null, "hl_context": "Microbiology is a broad term that encompasses the study of all different types of microorganisms . But in practice , microbiologists tend to specialize in one of several subfields . <hl> For example , bacteriology is the study of bacteria ; mycology is the study of fungi ; protozoology is the study of protozoa ; parasitology is the study of helminths and other parasites ; and virology is the study of viruses ( Figure 1.21 ) . <hl> Immunology , the study of the immune system , is often included in the study of microbiology because host – pathogen interactions are central to our understanding of infectious disease processes . <hl> Microbiologists can also specialize in certain areas of microbiology , such as clinical microbiology , environmental microbiology , applied microbiology , or food microbiology . <hl>", "hl_sentences": "For example , bacteriology is the study of bacteria ; mycology is the study of fungi ; protozoology is the study of protozoa ; parasitology is the study of helminths and other parasites ; and virology is the study of viruses ( Figure 1.21 ) . Microbiologists can also specialize in certain areas of microbiology , such as clinical microbiology , environmental microbiology , applied microbiology , or food microbiology .", "question": { "cloze_format": "___ is not a subfield of microbiology.", "normal_format": "Which of the following is not a subfield of microbiology?", "question_choices": [ "bacteriology", "botany", "clinical microbiology", "virology" ], "question_id": "fs-id1171360528335", "question_text": "Which of the following is not a subfield of microbiology?" }, "references_are_paraphrase": null } ]
1
1.1 What Our Ancestors Knew Learning Objectives Describe how our ancestors improved food with the use of invisible microbes Describe how the causes of sickness and disease were explained in ancient times, prior to the invention of the microscope Describe key historical events associated with the birth of microbiology Clinical Focus Part 1 Cora, a 41-year-old lawyer and mother of two, has recently been experiencing severe headaches, a high fever, and a stiff neck. Her husband, who has accompanied Cora to see a doctor, reports that Cora also seems confused at times and unusually drowsy. Based on these symptoms, the doctor suspects that Cora may have meningitis, a potentially life-threatening infection of the tissue that surrounds the brain and spinal cord. Meningitis has several potential causes. It can be brought on by bacteria, fungi, viruses, or even a reaction to medication or exposure to heavy metals. Although people with viral meningitis usually heal on their own, bacterial and fungal meningitis are quite serious and require treatment. Cora’s doctor orders a lumbar puncture (spinal tap) to take three samples of cerebrospinal fluid (CSF) from around the spinal cord ( Figure 1.2 ). The samples will be sent to laboratories in three different departments for testing: clinical chemistry, microbiology, and hematology. The samples will first be visually examined to determine whether the CSF is abnormally colored or cloudy; then the CSF will be examined under a microscope to see if it contains a normal number of red and white blood cells and to check for any abnormal cell types. In the microbiology lab, the specimen will be centrifuged to concentrate any cells in a sediment; this sediment will be smeared on a slide and stained with a Gram stain. Gram staining is a procedure used to differentiate between two different types of bacteria (gram-positive and gram-negative). About 80% of patients with bacterial meningitis will show bacteria in their CSF with a Gram stain. 2 Cora’s Gram stain did not show any bacteria, but her doctor decides to prescribe her antibiotics just in case. Part of the CSF sample will be cultured—put in special dishes to see if bacteria or fungi will grow. It takes some time for most microorganisms to reproduce in sufficient quantities to be detected and analyzed. 2 Rebecca Buxton. “Examination of Gram Stains of Spinal Fluid—Bacterial Meningitis.” American Society for Microbiology . 2007. http://www.microbelibrary.org/library/gram-stain/3065-examination-of-gram-stains-of-spinal-fluid-bacterial-meningitis What types of microorganisms would be killed by antibiotic treatment? Jump to the next Clinical Focus box. Most people today, even those who know very little about microbiology, are familiar with the concept of microbes, or “germs,” and their role in human health. Schoolchildren learn about bacteria, viruses, and other microorganisms, and many even view specimens under a microscope. But a few hundred years ago, before the invention of the microscope, the existence of many types of microbes was impossible to prove. By definition, microorganism s , or microbe s , are very small organisms; many types of microbes are too small to see without a microscope, although some parasites and fungi are visible to the naked eye. Humans have been living with—and using—microorganisms for much longer than they have been able to see them. Historical evidence suggests that humans have had some notion of microbial life since prehistoric times and have used that knowledge to develop foods as well as prevent and treat disease. In this section, we will explore some of the historical applications of microbiology as well as the early beginnings of microbiology as a science. Fermented Foods and Beverages People across the world have enjoyed fermented foods and beverages like beer, wine, bread, yogurt, cheese, and pickled vegetables for all of recorded history. Discoveries from several archeological sites suggest that even prehistoric people took advantage of fermentation to preserve and enhance the taste of food. Archaeologists studying pottery jars from a Neolithic village in China found that people were making a fermented beverage from rice, honey, and fruit as early as 7000 BC. 3 3 P.E. McGovern et al. “Fermented Beverages of Pre- and Proto-Historic China.” Proceedings of the National Academy of Sciences of the United States of America 1 no. 51 (2004):17593–17598. doi:10.1073/pnas.0407921102. Production of these foods and beverages requires microbial fermentation, a process that uses bacteria, mold, or yeast to convert sugars (carbohydrates) to alcohol, gases, and organic acids ( Figure 1.3 ). While it is likely that people first learned about fermentation by accident—perhaps by drinking old milk that had curdled or old grape juice that had fermented—they later learned to harness the power of fermentation to make products like bread, cheese, and wine. The Iceman Treateth Prehistoric humans had a very limited understanding of the causes of disease, and various cultures developed different beliefs and explanations. While many believed that illness was punishment for angering the gods or was simply the result of fate, archaeological evidence suggests that prehistoric people attempted to treat illnesses and infections. One example of this is Ötzi the Iceman , a 5300-year-old mummy found frozen in the ice of the Ötzal Alps on the Austrian-Italian border in 1991. Because Ötzi was so well preserved by the ice, researchers discovered that he was infected with the eggs of the parasite Trichuris trichiura , which may have caused him to have abdominal pain and anemia. Researchers also found evidence of Borrelia burgdorferi , a bacterium that causes Lyme disease. 4 Some researchers think Ötzi may have been trying to treat his infections with the woody fruit of the Fomitopsis betulinus fungus, which was discovered tied to his belongings. 5 This fungus has both laxative and antibiotic properties. Ötzi was also covered in tattoos that were made by cutting incisions into his skin, filling them with herbs, and then burning the herbs. 6 There is speculation that this may have been another attempt to treat his health ailments. 4 A. Keller et al. “New Insights into the Tyrolean Iceman's Origin and Phenotype as Inferred by Whole-Genome Sequencing.” Nature Communications , 3 (2012): 698. doi:10.1038/ncomms1701. 5 L. Capasso. “5300 Years Ago, the Ice Man Used Natural Laxatives and Antibiotics.” The Lancet , 352 (1998) 9143: 1864. doi: 10.1016/s0140-6736(05)79939-6. 6 L. Capasso, L. “5300 Years Ago, the Ice Man Used Natural Laxatives and Antibiotics.” The Lancet , 352 no. 9143 (1998): 1864. doi: 10.1016/s0140-6736(05)79939-6. Early Notions of Disease, Contagion, and Containment Several ancient civilizations appear to have had some understanding that disease could be transmitted by things they could not see. This is especially evident in historical attempts to contain the spread of disease. For example, the Bible refers to the practice of quarantining people with leprosy and other diseases, suggesting that people understood that diseases could be communicable. Ironically, while leprosy is communicable, it is also a disease that progresses slowly. This means that people were likely quarantined after they had already spread the disease to others. The ancient Greeks attributed disease to bad air, mal’aria , which they called “miasmatic odors.” They developed hygiene practices that built on this idea. The Romans also believed in the miasma hypothesis and created a complex sanitation infrastructure to deal with sewage. In Rome, they built aqueducts, which brought fresh water into the city, and a giant sewer, the Cloaca Maxima , which carried waste away and into the river Tiber ( Figure 1.4 ). Some researchers believe that this infrastructure helped protect the Romans from epidemics of waterborne illnesses. Even before the invention of the microscope, some doctors, philosophers, and scientists made great strides in understanding the invisible forces—what we now know as microbes—that can cause infection, disease, and death. The Greek physician Hippocrates (460–370 BC) is considered the “father of Western medicine” ( Figure 1.5 ). Unlike many of his ancestors and contemporaries, he dismissed the idea that disease was caused by supernatural forces. Instead, he posited that diseases had natural causes from within patients or their environments. Hippocrates and his heirs are believed to have written the Hippocratic Corpus , a collection of texts that make up some of the oldest surviving medical books. 7 Hippocrates is also often credited as the author of the Hippocratic Oath, taken by new physicians to pledge their dedication to diagnosing and treating patients without causing harm. 7 G. Pappas et al. “Insights Into Infectious Disease in the Era of Hippocrates.” International Journal of Infectious Diseases 12 (2008) 4:347–350. doi: http://dx.doi.org/10.1016/j.ijid.2007.11.003. While Hippocrates is considered the father of Western medicine, the Greek philosopher and historian Thucydides (460–395 BC) is considered the father of scientific history because he advocated for evidence-based analysis of cause-and-effect reasoning ( Figure 1.5 ). Among his most important contributions are his observations regarding the Athenian plague that killed one-third of the population of Athens between 430 and 410 BC. Having survived the epidemic himself, Thucydides made the important observation that survivors did not get re-infected with the disease, even when taking care of actively sick people. 8 This observation shows an early understanding of the concept of immunity. 8 Thucydides. The History of the Peloponnesian War. The Second Book . 431 BC. Translated by Richard Crawley. http://classics.mit.edu/Thucydides/pelopwar.2.second.html. Marcus Terentius Varro (116–27 BC) was a prolific Roman writer who was one of the first people to propose the concept that things we cannot see (what we now call microorganisms) can cause disease ( Figure 1.5 ). In Res Rusticae ( On Farming ), published in 36 BC, he said that “precautions must also be taken in neighborhood swamps . . . because certain minute creatures [ animalia minuta ] grow there which cannot be seen by the eye, which float in the air and enter the body through the mouth and nose and there cause serious diseases.” 9 9 Plinio Prioreschi. A History of Medicine: Roman Medicine . Lewiston, NY: Edwin Mellen Press, 1998: p. 215. Check Your Understanding Give two examples of foods that have historically been produced by humans with the aid of microbes. Explain how historical understandings of disease contributed to attempts to treat and contain disease. The Birth of Microbiology While the ancients may have suspected the existence of invisible “minute creatures,” it wasn’t until the invention of the microscope that their existence was definitively confirmed. While it is unclear who exactly invented the microscope, a Dutch cloth merchant named Antonie van Leeuwenhoek (1632–1723) was the first to develop a lens powerful enough to view microbes. In 1675, using a simple but powerful microscope, Leeuwenhoek was able to observe single-celled organisms, which he described as “animalcules” or “wee little beasties,” swimming in a drop of rain water. From his drawings of these little organisms, we now know he was looking at bacteria and protists. (We will explore Leeuwenhoek’s contributions to microscopy further in How We See the Invisible World .) Nearly 200 years after van Leeuwenhoek got his first glimpse of microbes, the “ Golden Age of Microbiology ” spawned a host of new discoveries between 1857 and 1914. Two famous microbiologists, Louis Pasteur and Robert Koch , were especially active in advancing our understanding of the unseen world of microbes ( Figure 1.6 ). Pasteur, a French chemist, showed that individual microbial strains had unique properties and demonstrated that fermentation is caused by microorganisms. He also invented pasteurization, a process used to kill microorganisms responsible for spoilage, and developed vaccines for the treatment of diseases, including rabies, in animals and humans. Koch, a German physician, was the first to demonstrate the connection between a single, isolated microbe and a known human disease. For example, he discovered the bacteria that cause anthrax ( Bacillus anthracis ), cholera ( Vibrio cholera ), and tuberculosis ( Mycobacterium tuberculosis ). 10 We will discuss these famous microbiologists, and others, in later chapters. 10 S.M. Blevins and M.S. Bronze. “Robert Koch and the ‘Golden Age’ of Bacteriology.” International Journal of Infectious Diseases . 14 no. 9 (2010): e744-e751. doi:10.1016/j.ijid.2009.12.003. As microbiology has developed, it has allowed the broader discipline of biology to grow and flourish in previously unimagined ways. Much of what we know about human cells comes from our understanding of microbes, and many of the tools we use today to study cells and their genetics derive from work with microbes. Check Your Understanding How did the discovery of microbes change human understanding of disease? Micro Connections Microbiology Toolbox Because individual microbes are generally too small to be seen with the naked eye, the science of microbiology is dependent on technology that can artificially enhance the capacity of our natural senses of perception. Early microbiologists like Pasteur and Koch had fewer tools at their disposal than are found in modern laboratories, making their discoveries and innovations that much more impressive. Later chapters of this text will explore many applications of technology in depth, but for now, here is a brief overview of some of the fundamental tools of the microbiology lab. Microscopes produce magnified images of microorganisms, human cells and tissues, and many other types of specimens too small to be observed with the naked eye. Stains and dyes are used to add color to microbes so they can be better observed under a microscope. Some dyes can be used on living microbes, whereas others require that the specimens be fixed with chemicals or heat before staining. Some stains only work on certain types of microbes because of differences in their cellular chemical composition. Growth media are used to grow microorganisms in a lab setting. Some media are liquids; others are more solid or gel-like. A growth medium provides nutrients, including water, various salts, a source of carbon (like glucose), and a source of nitrogen and amino acids (like yeast extract) so microorganisms can grow and reproduce. Ingredients in a growth medium can be modified to grow unique types of microorganisms. A Petri dish is a flat-lidded dish that is typically 10–11 centimeters (cm) in diameter and 1–1.5 cm high. Petri dishes made out of either plastic or glass are used to hold growth media ( Figure 1.7 ). Test tubes are cylindrical plastic or glass tubes with rounded bottoms and open tops. They can be used to grow microbes in broth, or semisolid or solid growth media. A Bunsen burner is a metal apparatus that creates a flame that can be used to sterilize pieces of equipment. A rubber tube carries gas (fuel) to the burner. In many labs, Bunsen burners are being phased out in favor of infrared microincinerators , which serve a similar purpose without the safety risks of an open flame. An inoculation loop is a handheld tool that ends in a small wire loop ( Figure 1.7 ). The loop can be used to streak microorganisms on agar in a Petri dish or to transfer them from one test tube to another. Before each use, the inoculation loop must be sterilized so cultures do not become contaminated. 1.2 A Systematic Approach Learning Objectives Describe how microorganisms are classified and distinguished as unique species Compare historical and current systems of taxonomy used to classify microorganisms Once microbes became visible to humans with the help of microscopes, scientists began to realize their enormous diversity. Microorganisms vary in all sorts of ways, including their size, their appearance, and their rates of reproduction. To study this incredibly diverse new array of organisms, researchers needed a way to systematically organize them. The Science of Taxonomy Taxonomy is the classification, description, identification, and naming of living organisms. Classification is the practice of organizing organisms into different groups based on their shared characteristics. The most famous early taxonomist was a Swedish botanist, zoologist, and physician named Carolus Linnaeus (1701–1778). In 1735, Linnaeus published Systema Naturae , an 11-page booklet in which he proposed the Linnaean taxonomy , a system of categorizing and naming organisms using a standard format so scientists could discuss organisms using consistent terminology. He continued to revise and add to the book, which grew into multiple volumes ( Figure 1.8 ). In his taxonomy, Linnaeus divided the natural world into three kingdoms: animal, plant, and mineral (the mineral kingdom was later abandoned). Within the animal and plant kingdoms, he grouped organisms using a hierarchy of increasingly specific levels and sublevels based on their similarities. The names of the levels in Linnaeus’s original taxonomy were kingdom, class, order, family, genus (plural: genera), and species. Species was, and continues to be, the most specific and basic taxonomic unit. Evolving Trees of Life (Phylogenies) With advances in technology, other scientists gradually made refinements to the Linnaean system and eventually created new systems for classifying organisms. In the 1800s, there was a growing interest in developing taxonomies that took into account the evolutionary relationships, or phylogenies , of all different species of organisms on earth. One way to depict these relationships is via a diagram called a phylogenetic tree (or tree of life). In these diagrams, groups of organisms are arranged by how closely related they are thought to be. In early phylogenetic trees, the relatedness of organisms was inferred by their visible similarities, such as the presence or absence of hair or the number of limbs. Now, the analysis is more complicated. Today, phylogenic analyses include genetic, biochemical, and embryological comparisons, as will be discussed later in this chapter. Linnaeus’s tree of life contained just two main branches for all living things: the animal and plant kingdoms. In 1866, Ernst Haeckel , a German biologist, philosopher, and physician, proposed another kingdom, Protista, for unicellular organisms ( Figure 1.9 ). He later proposed a fourth kingdom, Monera, for unicellular organisms whose cells lack nuclei, like bacteria. Nearly 100 years later, in 1969, American ecologist Robert Whittaker (1920–1980) proposed adding another kingdom—Fungi—in his tree of life. Whittaker’s tree also contained a level of categorization above the kingdom level—the empire or superkingdom level—to distinguish between organisms that have membrane-bound nuclei in their cells ( eukaryote s ) and those that do not ( prokaryote s ). Empire Prokaryota contained just the Kingdom Monera. The Empire Eukaryota contained the other four kingdoms: Fungi, Protista, Plantae, and Animalia. Whittaker’s five-kingdom tree was considered the standard phylogeny for many years. Figure 1.10 shows how the tree of life has changed over time. Note that viruses are not found in any of these trees. That is because they are not made up of cells and thus it is difficult to determine where they would fit into a tree of life. Check Your Understanding Briefly summarize how our evolving understanding of microorganisms has contributed to changes in the way that organisms are classified. Clinical Focus Part 2 Antibiotic drugs are specifically designed to kill or inhibit the growth of bacteria. But after a couple of days on antibiotics, Cora shows no signs of improvement. Also, her CSF cultures came back from the lab negative. Since bacteria or fungi were not isolated from Cora’s CSF sample, her doctor rules out bacterial and fungal meningitis. Viral meningitis is still a possibility. However, Cora now reports some troubling new symptoms. She is starting to have difficulty walking. Her muscle stiffness has spread from her neck to the rest of her body, and her limbs sometimes jerk involuntarily. In addition, Cora’s cognitive symptoms are worsening. At this point, Cora’s doctor becomes very concerned and orders more tests on the CSF samples. What types of microorganisms could be causing Cora’s symptoms? Jump to the next Clinical Focus box. Go back to the previous Clinical Focus box. The Role of Genetics in Modern Taxonomy Haeckel’s and Whittaker’s trees presented hypotheses about the phylogeny of different organisms based on readily observable characteristics. But the advent of molecular genetics in the late 20th century revealed other ways to organize phylogenetic trees. Genetic methods allow for a standardized way to compare all living organisms without relying on observable characteristics that can often be subjective. Modern taxonomy relies heavily on comparing the nucleic acids (deoxyribonucleic acid [DNA] or ribonucleic acid [RNA]) or proteins from different organisms. The more similar the nucleic acids and proteins are between two organisms, the more closely related they are considered to be. In the 1970s, American microbiologist Carl Woese discovered what appeared to be a “living record” of the evolution of organisms. He and his collaborator George Fox created a genetics-based tree of life based on similarities and differences they observed in the gene sequences coding for small subunit ribosomal RNA (rRNA) of different organisms. In the process, they discovered that a certain type of bacteria , called archaebacteria (now known simply as archaea ), were significantly different from other bacteria and eukaryotes in terms of their small subunit rRNA gene sequences. To accommodate this difference, they created a tree with three Domains above the level of Kingdom: Archaea, Bacteria, and Eukarya ( Figure 1.11 ). Analysis of small subunit rRNA gene sequences suggests archaea, bacteria, and eukaryotes all evolved from a common ancestral cell type. The tree is skewed to show a closer evolutionary relationship between Archaea and Eukarya than they have to Bacteria. Scientists continue to use analysis of RNA, DNA, and proteins to determine how organisms are related. One interesting, and complicating, discovery is that of horizontal gene transfer—when a gene of one species is absorbed into another organism’s genome. Horizontal gene transfer is especially common in microorganisms and can make it difficult to determine how organisms are evolutionarily related. Consequently, some scientists now think in terms of “webs of life” rather than “trees of life.” Check Your Understanding In modern taxonomy, how do scientists determine how closely two organisms are related? Explain why the branches on the “tree of life” all originate from a single “trunk.” Naming Microbes In developing his taxonomy, Linnaeus used a system of binomial nomenclature , a two-word naming system for identifying organisms by genus and specific epithet. For example, modern humans are in the genus Homo and have the specific epithet name sapiens , so their scientific name in binomial nomenclature is Homo sapiens . In binomial nomenclature, the genus part of the name is always capitalized; it is followed by the specific epithet name, which is not capitalized. Both names are italicized. When referring to the species of humans, the binomial nomenclature would be Homo sapiens . Taxonomic names in the 18th through 20th centuries were typically derived from Latin, since that was the common language used by scientists when taxonomic systems were first created. Today, newly discovered organisms can be given names derived from Latin, Greek, or English. Sometimes these names reflect some distinctive trait of the organism; in other cases, microorganisms are named after the scientists who discovered them. The archaeon Haloquadratum walsbyi is an example of both of these naming schemes. The genus, Haloquadratum , describes the microorganism’s saltwater habitat ( halo is derived from the Greek word for “salt”) as well as the arrangement of its square cells, which are arranged in square clusters of four cells ( quadratum is Latin for “foursquare”). The species, walsbyi , is named after Anthony Edward Walsby, the microbiologist who discovered Haloquadratum walsbyi in in 1980. While it might seem easier to give an organism a common descriptive name—like a red-headed woodpecker—we can imagine how that could become problematic. What happens when another species of woodpecker with red head coloring is discovered? The systematic nomenclature scientists use eliminates this potential problem by assigning each organism a single, unique two-word name that is recognized by scientists all over the world. In this text, we will typically abbreviate an organism’s genus and species after its first mention. The abbreviated form is simply the first initial of the genus, followed by a period and the full name of the species. For example, the bacterium Escherichia coli is shortened to E. coli in its abbreviated form. You will encounter this same convention in other scientific texts as well. Bergey’s Manuals Whether in a tree or a web, microbes can be difficult to identify and classify. Without easily observable macroscopic features like feathers, feet, or fur, scientists must capture, grow, and devise ways to study their biochemical properties to differentiate and classify microbes. Despite these hurdles, a group of microbiologists created and updated a set of manuals for identifying and classifying microorganisms. First published in 1923 and since updated many times, Bergey’s Manual of Determinative Bacteriology and Bergey’s Manual of Systematic Bacteriology are the standard references for identifying and classifying different prokaryotes. ( Appendix D of this textbook is partly based on Bergey’s manuals; it shows how the organisms that appear in this textbook are classified.) Because so many bacteria look identical, methods based on nonvisual characteristics must be used to identify them. For example, biochemical tests can be used to identify chemicals unique to certain species. Likewise, serological tests can be used to identify specific antibodies that will react against the proteins found in certain species. Ultimately, DNA and rRNA sequencing can be used both for identifying a particular bacterial species and for classifying newly discovered species. Check Your Understanding What is binomial nomenclature and why is it a useful tool for naming organisms? Explain why a resource like one of Bergey’s manuals would be helpful in identifying a microorganism in a sample. Micro Connections Same Name, Different Strain Within one species of microorganism, there can be several subtypes called strains. While different strains may be nearly identical genetically, they can have very different attributes. The bacterium Escherichia coli is infamous for causing food poisoning and traveler’s diarrhea. However, there are actually many different strains of E. coli , and they vary in their ability to cause disease. One pathogenic (disease-causing) E. coli strain that you may have heard of is E. coli O157:H7. In humans, infection from E. coli O157:H7 can cause abdominal cramps and diarrhea. Infection usually originates from contaminated water or food, particularly raw vegetables and undercooked meat. In the 1990s, there were several large outbreaks of E. coli O157:H7 thought to have originated in undercooked hamburgers. While E. coli O157:H7 and some other strains have given E. coli a bad name, most E. coli strains do not cause disease. In fact, some can be helpful. Different strains of E. coli found naturally in our gut help us digest our food, provide us with some needed chemicals, and fight against pathogenic microbes. Link to Learning Learn more about phylogenetic trees by exploring the Wellcome Trust’s interactive Tree of Life. The website contains information, photos, and animations about many different organisms. Select two organisms to see how they are evolutionarily related. 1.3 Types of Microorganisms Learning Objectives List the various types of microorganisms and describe their defining characteristics Give examples of different types of cellular and viral microorganisms and infectious agents Describe the similarities and differences between archaea and bacteria Provide an overview of the field of microbiology Most microbes are unicellular and small enough that they require artificial magnification to be seen. However, there are some unicellular microbes that are visible to the naked eye, and some multicellular organisms that are microscopic. An object must measure about 100 micrometers (µm) to be visible without a microscope, but most microorganisms are many times smaller than that. For some perspective, consider that a typical animal cell measures roughly 10 µm across but is still microscopic. Bacterial cells are typically about 1 µm, and viruses can be 10 times smaller than bacteria ( Figure 1.12 ). See Table 1.1 for units of length used in microbiology. Units of Length Commonly Used in Microbiology Metric Unit Meaning of Prefix Metric Equivalent meter (m) — 1 m = 10 0 m decimeter (dm) 1/10 1 dm = 0.1 m = 10 −1 m centimeter (cm) 1/100 1 cm = 0.01 m = 10 −2 m millimeter (mm) 1/1000 1 mm = 0.001 m = 10 −3 m micrometer (μm) 1/1,000,000 1 μm = 0.000001 m = 10 −6 m nanometer (nm) 1/1,000,000,000 1 nm = 0.000000001 m = 10 −9 m Table 1.1 Microorganisms differ from each other not only in size, but also in structure, habitat, metabolism, and many other characteristics. While we typically think of microorganisms as being unicellular, there are also many multicellular organisms that are too small to be seen without a microscope. Some microbes, such as viruses, are even acellular (not composed of cells). Microorganisms are found in each of the three domains of life: Archaea, Bacteria, and Eukarya. Microbes within the domains Bacteria and Archaea are all prokaryotes (their cells lack a nucleus), whereas microbes in the domain Eukarya are eukaryotes (their cells have a nucleus). Some microorganisms, such as viruses, do not fall within any of the three domains of life. In this section, we will briefly introduce each of the broad groups of microbes. Later chapters will go into greater depth about the diverse species within each group. Link to Learning How big is a bacterium or a virus compared to other objects? Check out this interactive website to get a feel for the scale of different microorganisms. Prokaryotic Microorganisms Bacteria are found in nearly every habitat on earth, including within and on humans. Most bacteria are harmless or helpful, but some are pathogen s , causing disease in humans and other animals. Bacteria are prokaryotic because their genetic material (DNA) is not housed within a true nucleus. Most bacteria have cell walls that contain peptidoglycan. Bacteria are often described in terms of their general shape. Common shapes include spherical (coccus), rod-shaped (bacillus), or curved (spirillum, spirochete, or vibrio). Figure 1.13 shows examples of these shapes. They have a wide range of metabolic capabilities and can grow in a variety of environments, using different combinations of nutrients. Some bacteria are photosynthetic, such as oxygenic cyanobacteria and anoxygenic green sulfur and green nonsulfur bacteria; these bacteria use energy derived from sunlight, and fix carbon dioxide for growth. Other types of bacteria are nonphotosynthetic, obtaining their energy from organic or inorganic compounds in their environment. Archaea are also unicellular prokaryotic organisms. Archaea and bacteria have different evolutionary histories, as well as significant differences in genetics, metabolic pathways, and the composition of their cell walls and membranes. Unlike most bacteria, archaeal cell walls do not contain peptidoglycan, but their cell walls are often composed of a similar substance called pseudopeptidoglycan. Like bacteria, archaea are found in nearly every habitat on earth, even extreme environments that are very cold, very hot, very basic, or very acidic ( Figure 1.14 ). Some archaea live in the human body, but none have been shown to be human pathogens. Check Your Understanding What are the two main types of prokaryotic organisms? Name some of the defining characteristics of each type. Eukaryotic Microorganisms The domain Eukarya contains all eukaryotes, including uni- or multicellular eukaryotes such as protists, fungi, plants, and animals. The major defining characteristic of eukaryotes is that their cells contain a nucleus. Protists Protist s are an informal grouping of eukaryotes that are not plants, animals, or fungi. Algae and protozoa are examples of protists. Algae (singular: alga) are protists that can be either unicellular or multicellular and vary widely in size, appearance, and habitat ( Figure 1.15 ). Their cells are surrounded by cell walls made of cellulose, a type of carbohydrate. Algae are photosynthetic organisms that extract energy from the sun and release oxygen and carbohydrates into their environment. Because other organisms can use their waste products for energy, algae are important parts of many ecosystems. Many consumer products contain ingredients derived from algae, such as carrageenan or alginic acid, which are found in some brands of ice cream, salad dressing, beverages, lipstick, and toothpaste. A derivative of algae also plays a prominent role in the microbiology laboratory. Agar, a gel derived from algae, can be mixed with various nutrients and used to grow microorganisms in a Petri dish. Algae are also being developed as a possible source for biofuels. Protozoa (singular: protozoan) are protists that make up the backbone of many food webs by providing nutrients for other organisms. Protozoa are very diverse. Some protozoa move with help from hair-like structures called cilia or whip-like structures called flagella. Others extend part of their cell membrane and cytoplasm to propel themselves forward. These cytoplasmic extensions are called pseudopods (“false feet”). Some protozoa are photosynthetic; others feed on organic material. Some are free-living, whereas others are parasitic, only able to survive by extracting nutrients from a host organism. Most protozoa are harmless, but some are pathogens that can cause disease in animals or humans ( Figure 1.16 ). Fungi Fungi (singular: fungus) are also eukaryotes. Some multicellular fungi, such as mushrooms, resemble plants, but they are actually quite different. Fungi are not photosynthetic, and their cell walls are usually made out of chitin rather than cellulose. Unicellular fungi—yeasts—are included within the study of microbiology. There are more than 1000 known species. Yeasts are found in many different environments, from the deep sea to the human navel. Some yeasts have beneficial uses, such as causing bread to rise and beverages to ferment; but yeasts can also cause food to spoil. Some even cause diseases, such as vaginal yeast infections and oral thrush ( Figure 1.17 ). Other fungi of interest to microbiologists are multicellular organisms called mold s . Molds are made up of long filaments that form visible colonies ( Figure 1.18 ). Molds are found in many different environments, from soil to rotting food to dank bathroom corners. Molds play a critical role in the decomposition of dead plants and animals. Some molds can cause allergies, and others produce disease-causing metabolites called mycotoxins. Molds have been used to make pharmaceuticals, including penicillin, which is one of the most commonly prescribed antibiotics, and cyclosporine, used to prevent organ rejection following a transplant. Check Your Understanding Name two types of protists and two types of fungi. Name some of the defining characteristics of each type. Helminths Multicellular parasitic worms called helminth s are not technically microorganisms, as most are large enough to see without a microscope. However, these worms fall within the field of microbiology because diseases caused by helminths involve microscopic eggs and larvae. One example of a helminth is the guinea worm , or Dracunculus medinensis , which causes dizziness, vomiting, diarrhea, and painful ulcers on the legs and feet when the worm works its way out of the skin ( Figure 1.19 ). Infection typically occurs after a person drinks water containing water fleas infected by guinea-worm larvae. In the mid-1980s, there were an estimated 3.5 million cases of guinea-worm disease, but the disease has been largely eradicated. In 2014, there were only 126 cases reported, thanks to the coordinated efforts of the World Health Organization (WHO) and other groups committed to improvements in drinking water sanitation. 11 12 11 C. Greenaway “Dracunculiasis (Guinea Worm Disease).” Canadian Medical Association Journal 170 no. 4 (2004):495–500. 12 World Health Organization. “Dracunculiasis (Guinea-Worm Disease).” WHO . 2015. http://www.who.int/mediacentre/factsheets/fs359/en/. Accessed October 2, 2015. Viruses Virus es are acellular microorganisms, which means they are not composed of cells. Essentially, a virus consists of proteins and genetic material—either DNA or RNA, but never both—that are inert outside of a host organism. However, by incorporating themselves into a host cell, viruses are able to co-opt the host’s cellular mechanisms to multiply and infect other hosts. Viruses can infect all types of cells, from human cells to the cells of other microorganisms. In humans, viruses are responsible for numerous diseases, from the common cold to deadly Ebola ( Figure 1.20 ). However, many viruses do not cause disease. Check Your Understanding Are helminths microorganisms? Explain why or why not. How are viruses different from other microorganisms? Microbiology as a Field of Study Microbiology is a broad term that encompasses the study of all different types of microorganisms. But in practice, microbiologists tend to specialize in one of several subfields. For example, bacteriology is the study of bacteria; mycology is the study of fungi; protozoology is the study of protozoa; parasitology is the study of helminths and other parasites; and virology is the study of viruses ( Figure 1.21 ). Immunology , the study of the immune system, is often included in the study of microbiology because host–pathogen interactions are central to our understanding of infectious disease processes. Microbiologists can also specialize in certain areas of microbiology, such as clinical microbiology, environmental microbiology, applied microbiology, or food microbiology. In this textbook, we are primarily concerned with clinical applications of microbiology, but since the various subfields of microbiology are highly interrelated, we will often discuss applications that are not strictly clinical. Eye on Ethics Bioethics in Microbiology In the 1940s, the U.S. government was looking for a solution to a medical problem: the prevalence of sexually transmitted diseases (STDs) among soldiers. Several now-infamous government-funded studies used human subjects to research common STDs and treatments. In one such study, American researchers intentionally exposed more than 1300 human subjects in Guatemala to syphilis, gonorrhea, and chancroid to determine the ability of penicillin and other antibiotics to combat these diseases. Subjects of the study included Guatemalan soldiers, prisoners, prostitutes, and psychiatric patients—none of whom were informed that they were taking part in the study. Researchers exposed subjects to STDs by various methods, from facilitating intercourse with infected prostitutes to inoculating subjects with the bacteria known to cause the diseases. This latter method involved making a small wound on the subject’s genitals or elsewhere on the body, and then putting bacteria directly into the wound. 13 In 2011, a U.S. government commission tasked with investigating the experiment revealed that only some of the subjects were treated with penicillin, and 83 subjects died by 1953, likely as a result of the study. 14 13 Kara Rogers. “Guatemala Syphilis Experiment: American Medical Research Project”. Encylopaedia Britannica . http://www.britannica.com/event/Guatemala-syphilis-experiment. Accessed June 24, 2015. 14 Susan Donaldson James. “Syphilis Experiments Shock, But So Do Third-World Drug Trials.” ABC World News . August 30, 2011. http://abcnews.go.com/Health/guatemala-syphilis-experiments-shock-us-drug-trials-exploit/story?id=14414902. Accessed June 24, 2015. Unfortunately, this is one of many horrific examples of microbiology experiments that have violated basic ethical standards. Even if this study had led to a life-saving medical breakthrough (it did not), few would argue that its methods were ethically sound or morally justifiable. But not every case is so clear cut. Professionals working in clinical settings are frequently confronted with ethical dilemmas, such as working with patients who decline a vaccine or life-saving blood transfusion. These are just two examples of life-and-death decisions that may intersect with the religious and philosophical beliefs of both the patient and the health-care professional. No matter how noble the goal, microbiology studies and clinical practice must be guided by a certain set of ethical principles. Studies must be done with integrity. Patients and research subjects provide informed consent (not only agreeing to be treated or studied but demonstrating an understanding of the purpose of the study and any risks involved). Patients’ rights must be respected. Procedures must be approved by an institutional review board. When working with patients, accurate record-keeping, honest communication, and confidentiality are paramount. Animals used for research must be treated humanely, and all protocols must be approved by an institutional animal care and use committee. These are just a few of the ethical principles explored in the Eye on Ethics boxes throughout this book. Clinical Focus Resolution Cora’s CSF samples show no signs of inflammation or infection, as would be expected with a viral infection. However, there is a high concentration of a particular protein, 14-3-3 protein, in her CSF. An electroencephalogram (EEG) of her brain function is also abnormal. The EEG resembles that of a patient with a neurodegenerative disease like Alzheimer’s or Huntington’s, but Cora’s rapid cognitive decline is not consistent with either of these. Instead, her doctor concludes that Cora has Creutzfeldt-Jakob disease (CJD) , a type of transmissible spongiform encephalopathy (TSE). CJD is an extremely rare disease, with only about 300 cases in the United States each year. It is not caused by a bacterium, fungus, or virus, but rather by prions —which do not fit neatly into any particular category of microbe. Like viruses, prions are not found on the tree of life because they are acellular. Prions are extremely small, about one-tenth the size of a typical virus. They contain no genetic material and are composed solely of a type of abnormal protein. CJD can have several different causes. It can be acquired through exposure to the brain or nervous-system tissue of an infected person or animal. Consuming meat from an infected animal is one way such exposure can occur. There have also been rare cases of exposure to CJD through contact with contaminated surgical equipment 15 and from cornea and growth-hormone donors who unknowingly had CJD. 16 17 In rare cases, the disease results from a specific genetic mutation that can sometimes be hereditary. However, in approximately 85% of patients with CJD, the cause of the disease is spontaneous (or sporadic) and has no identifiable cause. 18 Based on her symptoms and their rapid progression, Cora is diagnosed with sporadic CJD. 15 Greg Botelho. “Case of Creutzfeldt-Jakob Disease Confirmed in New Hampshire.” CNN . 2013. http://www.cnn.com/2013/09/20/health/creutzfeldt-jakob-brain-disease/. 16 P. Rudge et al. “Iatrogenic CJD Due to Pituitary-Derived Growth Hormone With Genetically Determined Incubation Times of Up to 40 Years.” Brain 138 no. 11 (2015): 3386–3399. 17 J.G. Heckmann et al. “Transmission of Creutzfeldt-Jakob Disease via a Corneal Transplant.” Journal of Neurology, Neurosurgery & Psychiatry 63 no. 3 (1997): 388–390. 18 National Institute of Neurological Disorders and Stroke. “Creutzfeldt-Jakob Disease Fact Sheet.” NIH . 2015. http://www.ninds.nih.gov/disorders/cjd/detail_cjd.htm#288133058. Unfortunately for Cora, CJD is a fatal disease for which there is no approved treatment. Approximately 90% of patients die within 1 year of diagnosis. 19 Her doctors focus on limiting her pain and cognitive symptoms as her disease progresses. Eight months later, Cora dies. Her CJD diagnosis is confirmed with a brain autopsy. 19 National Institute of Neurological Disorders and Stroke. “Creutzfeldt-Jakob Disease Fact Sheet.” NIH . 2015. http://www.ninds.nih.gov/disorders/cjd/detail_cjd.htm#288133058. Accessed June 22, 2015. Go back to the previous Clinical Focus box.
u.s._history
Summary 9.1 Early Industrialization in the Northeast Industrialization led to radical changes in American life. New industrial towns, like Waltham, Lowell, and countless others, dotted the landscape of the Northeast. The mills provided many young women an opportunity to experience a new and liberating life, and these workers relished their new freedom. Workers also gained a greater appreciation of the value of their work and, in some instances, began to question the basic fairness of the new industrial order. The world of work had been fundamentally reorganized. 9.2 A Vibrant Capitalist Republic The selling of the public domain was one of the key features of the early nineteenth century in the United States. Thousands rushed west to take part in the bounty. In the wild frenzy of land purchases and speculation in land, state banks advanced risky loans and created unstable paper money not backed by gold or silver, ultimately leading to the Panic of 1819. The ensuing economic depression was the first in U.S. history. Recovery came in the 1820s, followed by a period of robust growth. In this age of entrepreneurship, in which those who invested their money wisely in land, business ventures, or technological improvements reaped vast profits, inventors produced new wonders that transformed American life. 9.3 On the Move: The Transportation Revolution A transportation infrastructure rapidly took shape in the 1800s as American investors and the government began building roads, turnpikes, canals, and railroads. The time required to travel shrank vastly, and people marveled at their ability to conquer great distances, enhancing their sense of the steady advance of progress. The transportation revolution also made it possible to ship agricultural and manufactured goods throughout the country and enabled rural people to travel to towns and cities for employment opportunities. 9.4 A New Social Order: Class Divisions The creation of distinctive classes in the North drove striking new cultural developments. Even among the wealthy elites, northern business families, who had mainly inherited their money, distanced themselves from the newly wealthy manufacturing leaders. Regardless of how they had earned their money, however, the elite lived and socialized apart from members of the growing middle class. The middle class valued work, consumption, and education and dedicated their energies to maintaining or advancing their social status. Wage workers formed their own society in industrial cities and mill villages, though lack of money and long working hours effectively prevented the working class from consuming the fruits of their labor, educating their children, or advancing up the economic ladder.
Chapter Outline 9.1 Early Industrialization in the Northeast 9.2 A Vibrant Capitalist Republic 9.3 On the Move: The Transportation Revolution 9.4 A New Social Order: Class Divisions Introduction By the 1830s, the United States had developed a thriving industrial and commercial sector in the Northeast. Farmers embraced regional and distant markets as the primary destination for their products. Artisans witnessed the methodical division of the labor process in factories. Wage labor became an increasingly common experience. These industrial and market revolutions, combined with advances in transportation, transformed the economic and social landscape. Americans could now quickly produce larger amounts of goods for a nationwide, and sometimes an international, market and rely less on foreign imports than in colonial times. As American economic life shifted rapidly and modes of production changed, new class divisions emerged and solidified, resulting in previously unknown economic and social inequalities. This image of the Five Points district in New York City captures the turbulence of the time ( Figure 9.1 ). Five Points began as a settlement for freed formerly enslaved people, but it soon became a crowded urban world of American day laborers and low-wage workers who lived a precarious existence that the economic benefits of the new economy largely bypassed. An influx of immigrant workers swelled and diversified an already crowded urban population. By the 1830s, the area had become a slum, home to widespread poverty, crime, and disease. Advances in industrialization and the market revolution came at a human price.
[ { "answer": { "ans_choice": 2, "ans_text": "C" }, "bloom": null, "hl_context": "The success of Slater and his partners Smith Brown and William Almy , relatives of Moses Brown , inspired others to build additional mills in Rhode Island and Massachusetts . By 1807 , thirteen more mills had been established . <hl> President Jefferson ’ s embargo on British manufactured goods from late 1807 to early 1809 ( discussed in a previous chapter ) spurred more New England merchants to invest in industrial enterprises . <hl> <hl> By 1812 , seventy-eight new textile mills had been built in rural New England towns . <hl> More than half turned out woolen goods , while the rest produced cotton cloth . <hl> Some skilled British mechanics , including Samuel Slater , managed to travel to the United States in the hopes of profiting from their knowledge and experience with advanced textile manufacturing . <hl> <hl> Slater ( Figure 9.3 ) understood the workings of the latest water-powered textile mills , which British industrialist Richard Arkwright had pioneered . <hl> In the 1790s in Pawtucket , Rhode Island , Slater convinced several American merchants , including the wealthy Providence industrialist Moses Brown , to finance and build a water-powered cotton mill based on the British models . Slater ’ s knowledge of both technology and mill organization made him the founder of the first truly successful cotton mill in the United States .", "hl_sentences": "President Jefferson ’ s embargo on British manufactured goods from late 1807 to early 1809 ( discussed in a previous chapter ) spurred more New England merchants to invest in industrial enterprises . By 1812 , seventy-eight new textile mills had been built in rural New England towns . Some skilled British mechanics , including Samuel Slater , managed to travel to the United States in the hopes of profiting from their knowledge and experience with advanced textile manufacturing . Slater ( Figure 9.3 ) understood the workings of the latest water-powered textile mills , which British industrialist Richard Arkwright had pioneered .", "question": { "cloze_format": "The New England textile mills planned and built ___.", "normal_format": "How were the New England textile mills planned and built?", "question_choices": [ "Experienced British builders traveled to the United States to advise American merchants.", "New England merchants paid French and German mechanics to design factories for them.", "New England merchants and British migrants memorized plans from British mills.", "Textile mills were a purely American creation, invented by Francis Cabot Lowell in 1813." ], "question_id": "fs-idm49844128", "question_text": "How were the New England textile mills planned and built?" }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 3, "ans_text": "young farm women whose behavior was closely monitored" }, "bloom": null, "hl_context": "Needing to reassure anxious parents that their daughters ’ virtue would be protected and hoping to avoid what they viewed as the problems of industrialization — filth and vice — the Boston Associates established strict rules governing the lives of these young workers . The women lived in company-owned boarding houses to which they paid a portion of their wages . They woke early at the sound of a bell and worked a twelve-hour day during which talking was forbidden . They could not swear or drink alcohol , and they were required to attend church on Sunday . <hl> Overseers at the mills and boarding-house keepers kept a close eye on the young women ’ s behavior ; workers who associated with people of questionable reputation or acted in ways that called their virtue into question lost their jobs and were evicted . <hl> In contrast to many smaller mills , the Boston Associates ’ enterprises avoided the Rhode Island system , preferring individual workers to families . These employees were not difficult to find . The competition New England farmers faced from farmers now settling in the West , and the growing scarcity of land in population-dense New England , had important implications for farmers ’ children . Realizing their chances of inheriting a large farm or receiving a substantial dowry were remote , these teenagers sought other employment opportunities , often at the urging of their parents . While young men could work at a variety of occupations , young women had more limited options . <hl> The textile mills provided suitable employment for the daughters of Yankee farm families . <hl>", "hl_sentences": "Overseers at the mills and boarding-house keepers kept a close eye on the young women ’ s behavior ; workers who associated with people of questionable reputation or acted in ways that called their virtue into question lost their jobs and were evicted . The textile mills provided suitable employment for the daughters of Yankee farm families .", "question": { "cloze_format": "Textile mill workers in the early nineteenth century were ___.", "normal_format": "Which is the best characterization of textile mill workers in the early nineteenth century?", "question_choices": [ "male and female indentured servants from Great Britain who worked hard to win their freedom", "young men who found freedom in the rowdy lifestyle of mill work", "experienced artisans who shared their knowledge in exchange for part ownership in the company", "young farm women whose behavior was closely monitored" ], "question_id": "fs-idm55389968", "question_text": "Which is the best characterization of textile mill workers in the early nineteenth century?" }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 1, "ans_text": "west toward Ohio" }, "bloom": null, "hl_context": "<hl> In the early nineteenth century , people poured into the territories west of the long-settled eastern seaboard . <hl> <hl> Among them were speculators seeking to buy cheap parcels from the federal government in anticipation of a rise in prices . <hl> <hl> The Ohio Country in the Northwest Territory appeared to offer the best prospects for many in the East , especially New Englanders . <hl> The result was “ Ohio fever , ” as thousands traveled there to reap the benefits of settling in this newly available territory ( Figure 9.7 ) .", "hl_sentences": "In the early nineteenth century , people poured into the territories west of the long-settled eastern seaboard . Among them were speculators seeking to buy cheap parcels from the federal government in anticipation of a rise in prices . The Ohio Country in the Northwest Territory appeared to offer the best prospects for many in the East , especially New Englanders .", "question": { "cloze_format": "Most people who migrated within the United States in the early nineteenth century went ________.", "normal_format": "Where did most people who migrated within the United States in the early nineteenth century go?", "question_choices": [ "north toward Canada", "west toward Ohio", "south toward Georgia", "east across the Mississippi River" ], "question_id": "fs-idp22831168", "question_text": "Most people who migrated within the United States in the early nineteenth century went ________." }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 3, "ans_text": "D" }, "bloom": null, "hl_context": "<hl> In 1818 , the Second Bank of the United States needed specie to pay foreign investors who had loaned money to the United States to enable the country to purchase Louisiana . <hl> <hl> The bank began to call in the loans it had made and required that state banks pay their debts in gold and silver . <hl> <hl> State banks that could not collect loan payments from hard-pressed farmers could not , in turn , meet their obligations to the Second Bank of the United States . <hl> Severe consequences followed as banks closed their doors and businesses failed . Three-quarters of the work force in Philadelphia was unemployed , and charities were swamped by thousands of newly destitute people needing assistance . In states with imprisonment for debt , the prison population swelled . As a result , many states drafted laws to provide relief for debtors . <hl> Even those at the top of the social ladder were affected by the Panic of 1819 . <hl> Thomas Jefferson , who had cosigned a loan for a friend , nearly lost Monticello when his acquaintance defaulted , leaving Jefferson responsible for the debt . The inflated economic bubble burst in 1819 , resulting in a prolonged economic depression or severe downturn in the economy called the Panic of 1819 . It was the first economic depression experienced by the American public , who panicked as they saw the prices of agricultural products fall and businesses fail . <hl> Prices had already begun falling in 1815 , at the end of the Napoleonic Wars , when Britain began to “ dump ” its surplus manufactured goods , the result of wartime overproduction , in American ports , where they were sold for low prices and competed with American-manufactured goods . <hl> <hl> In 1818 , to make the economic situation worse , prices for American agricultural products began to fall both in the United States and in Europe ; the overproduction of staples such as wheat and cotton coincided with the recovery of European agriculture , which reduced demand for American crops . <hl> Crop prices tumbled by as much 75 percent . In an effort to bring stability to the nation ’ s banking system , Congress chartered the Second Bank of the United States ( a revival of Alexander Hamilton ’ s national bank ) in 1816 . <hl> But this new institution only compounded the problem by making risky loans , opening branches in the South and West where land fever was highest , and issuing a steady stream of Bank of the United States notes , a move that increased inflation and speculation . <hl> Many Americans were struck with “ land fever . ” Farmers strove to expand their acreage , and those who lived in areas where unoccupied land was scarce sought holdings in the West . They needed money to purchase this land , however . Small merchants and factory owners , hoping to take advantage of this boom time , also sought to borrow money to expand their businesses . <hl> When existing banks refused to lend money to small farmers and others without a credit history , state legislatures chartered new banks to meet the demand . <hl> In one legislative session , Kentucky chartered forty-six . As loans increased , paper money from new state banks flooded the country , creating inflation that drove the price of land and goods still higher . This , in turn , encouraged even more people to borrow money with which to purchase land or to expand or start their own businesses . Speculators took advantage of this boom in the sale of land by purchasing property not to live on , but to buy cheaply and resell at exorbitant prices .", "hl_sentences": "In 1818 , the Second Bank of the United States needed specie to pay foreign investors who had loaned money to the United States to enable the country to purchase Louisiana . The bank began to call in the loans it had made and required that state banks pay their debts in gold and silver . State banks that could not collect loan payments from hard-pressed farmers could not , in turn , meet their obligations to the Second Bank of the United States . Even those at the top of the social ladder were affected by the Panic of 1819 . Prices had already begun falling in 1815 , at the end of the Napoleonic Wars , when Britain began to “ dump ” its surplus manufactured goods , the result of wartime overproduction , in American ports , where they were sold for low prices and competed with American-manufactured goods . In 1818 , to make the economic situation worse , prices for American agricultural products began to fall both in the United States and in Europe ; the overproduction of staples such as wheat and cotton coincided with the recovery of European agriculture , which reduced demand for American crops . But this new institution only compounded the problem by making risky loans , opening branches in the South and West where land fever was highest , and issuing a steady stream of Bank of the United States notes , a move that increased inflation and speculation . When existing banks refused to lend money to small farmers and others without a credit history , state legislatures chartered new banks to meet the demand .", "question": { "cloze_format": "___ was not a cause of the Panic of 1819.", "normal_format": "Which of the following was not a cause of the Panic of 1819?", "question_choices": [ "The Second Bank of the United States made risky loans.", "States chartered too many banks.", "Prices for American commodities dropped.", "Banks hoarded gold and silver." ], "question_id": "fs-idm83857664", "question_text": "Which of the following was not a cause of the Panic of 1819?" }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 2, "ans_text": "the steamship engine" }, "bloom": null, "hl_context": "<hl> Another influential new technology of the early 1800s was the steamship engine , invented by Robert Fulton in 1807 . <hl> Fulton ’ s first steamship , the Clermont , used paddle wheels to travel the 150 miles from New York City to Albany in a record time of only thirty-two hours ( Figure 9.11 ) . Soon , a fleet of steamboats was traversing the Hudson River and New York Harbor , later expanding to travel every major American river including the mighty Mississippi . By the 1830s there were over one thousand of these vessels , radically changing water transportation by ending its dependence on the wind . Steamboats could travel faster and more cheaply than sailing vessels or keelboats , which floated downriver and had to be poled or towed upriver on the return voyage . Steamboats also arrived with much greater dependability . The steamboat facilitated the rapid economic development of the massive Mississippi River Valley and the settlement of the West .", "hl_sentences": "Another influential new technology of the early 1800s was the steamship engine , invented by Robert Fulton in 1807 .", "question": { "cloze_format": "Robert Fulton is known for inventing ________.", "normal_format": "Robert Fulton is known for inventing what?", "question_choices": [ "the cotton gin", "the mechanical reaper", "the steamship engine", "machine tools" ], "question_id": "fs-idp49180480", "question_text": "Robert Fulton is known for inventing ________." }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 2, "ans_text": "the combustion engine" }, "bloom": null, "hl_context": "Starting in the late 1820s , steam locomotives began to compete with horse-drawn locomotives . <hl> The railroads with steam locomotives offered a new mode of transportation that fascinated citizens , buoying their optimistic view of the possibilities of technological progress . <hl> The Mohawk and Hudson Railroad was the first to begin service with a steam locomotive . Its inaugural train ran in 1831 on a track outside Albany and covered twelve miles in twenty-five minutes . Soon it was traveling regularly between Albany and Schenectady . <hl> One key part of the transportation revolution was the widespread building of roads and turnpikes . <hl> <hl> In 1811 , construction began on the Cumberland Road , a national highway that provided thousands with a route from Maryland to Illinois . <hl> The federal government funded this important artery to the West , beginning the creation of a transportation infrastructure for the benefit of settlers and farmers . Other entities built turnpikes , which ( as today ) charged fees for use . New York State , for instance , chartered turnpike companies that dramatically increased the miles of state roads from one thousand in 1810 to four thousand by 1820 . New York led the way in building turnpikes . <hl> New technologies , like the steamship and railroad lines , had brought about what historians call the transportation revolution . <hl> <hl> States competed for the honor of having the most advanced transport systems . <hl> People celebrated the transformation of the wilderness into an orderly world of improvement demonstrating the steady march of progress and the greatness of the republic . In 1817 , John C . Calhoun of South Carolina looked to a future of rapid internal improvements , declaring , “ Let us . . . bind the Republic together with a perfect system of roads and canals . ” Americans agreed that internal transportation routes would promote progress . <hl> By the eve of the Civil War , the United States had moved beyond roads and canals to a well-established and extensive system of railroads . <hl> Americans in the early 1800s were a people on the move , as thousands left the eastern coastal states for opportunities in the West . Unlike their predecessors , who traveled by foot or wagon train , these settlers had new transport options . <hl> Their trek was made possible by the construction of roads , canals , and railroads , projects that required the funding of the federal government and the states . <hl>", "hl_sentences": "The railroads with steam locomotives offered a new mode of transportation that fascinated citizens , buoying their optimistic view of the possibilities of technological progress . One key part of the transportation revolution was the widespread building of roads and turnpikes . In 1811 , construction began on the Cumberland Road , a national highway that provided thousands with a route from Maryland to Illinois . New technologies , like the steamship and railroad lines , had brought about what historians call the transportation revolution . States competed for the honor of having the most advanced transport systems . By the eve of the Civil War , the United States had moved beyond roads and canals to a well-established and extensive system of railroads . Their trek was made possible by the construction of roads , canals , and railroads , projects that required the funding of the federal government and the states .", "question": { "cloze_format": "___ is not a factor in the transportation revolution.", "normal_format": "Which of the following was not a factor in the transportation revolution?", "question_choices": [ "the steam-powered locomotive", "the canal system", "the combustion engine", "the government-funded road system" ], "question_id": "fs-idm141926624", "question_text": "Which of the following was not a factor in the transportation revolution?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 0, "ans_text": "A" }, "bloom": null, "hl_context": "<hl> As with highway projects such as the Cumberland Road , many canals were federally sponsored , especially during the presidency of John Quincy Adams in the late 1820s . <hl> Adams , along with Secretary of State Henry Clay , championed what was known as the American System , part of which included plans for a broad range of internal transportation improvements . <hl> Adams endorsed the creation of roads and canals to facilitate commerce and develop markets for agriculture as well as to advance settlement in the West . <hl> <hl> One key part of the transportation revolution was the widespread building of roads and turnpikes . <hl> <hl> In 1811 , construction began on the Cumberland Road , a national highway that provided thousands with a route from Maryland to Illinois . <hl> The federal government funded this important artery to the West , beginning the creation of a transportation infrastructure for the benefit of settlers and farmers . Other entities built turnpikes , which ( as today ) charged fees for use . New York State , for instance , chartered turnpike companies that dramatically increased the miles of state roads from one thousand in 1810 to four thousand by 1820 . New York led the way in building turnpikes . <hl> Americans in the early 1800s were a people on the move , as thousands left the eastern coastal states for opportunities in the West . <hl> <hl> Unlike their predecessors , who traveled by foot or wagon train , these settlers had new transport options . <hl> <hl> Their trek was made possible by the construction of roads , canals , and railroads , projects that required the funding of the federal government and the states . <hl>", "hl_sentences": "As with highway projects such as the Cumberland Road , many canals were federally sponsored , especially during the presidency of John Quincy Adams in the late 1820s . Adams endorsed the creation of roads and canals to facilitate commerce and develop markets for agriculture as well as to advance settlement in the West . One key part of the transportation revolution was the widespread building of roads and turnpikes . In 1811 , construction began on the Cumberland Road , a national highway that provided thousands with a route from Maryland to Illinois . Americans in the early 1800s were a people on the move , as thousands left the eastern coastal states for opportunities in the West . Unlike their predecessors , who traveled by foot or wagon train , these settlers had new transport options . Their trek was made possible by the construction of roads , canals , and railroads , projects that required the funding of the federal government and the states .", "question": { "cloze_format": "The significance ot the Cumberland Road was ___.", "normal_format": "What was the significance of the Cumberland Road?", "question_choices": [ "It gave settlers a quicker way to move west.", "It reduced the time it took to move goods from New York Harbor to Lake Erie.", "It improved trade from the Port of New Orleans.", "It was the first paved road." ], "question_id": "fs-idm17521120", "question_text": "What was the significance of the Cumberland Road?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 3, "ans_text": "D" }, "bloom": null, "hl_context": "Northern business elites , many of whom owned or had invested in businesses like cotton mills that profited from slave labor , often viewed the institution of slavery with ambivalence . <hl> Most members of the middle class took a dim view of it , however , since it promoted a culture of leisure . <hl> <hl> Slavery stood as the antithesis of the middle-class view that dignity and respectability were achieved through work , and many members of this class became active in efforts to end it . <hl> Industrial elites created chambers of commerce to advance their interests ; by 1858 there were ten in the United States . These networking organizations allowed top bankers and merchants to stay current on the economic activities of their peers and further strengthen the bonds among themselves . The elite also established social clubs to forge and maintain ties . The first of these , the Philadelphia Club , came into being in 1834 . Similar clubs soon formed in other cities and hosted a range of social activities designed to further bind together the leading economic families . <hl> Many northern elites worked hard to ensure the transmission of their inherited wealth from one generation to the next . <hl> <hl> Politically , they exercised considerable power in local and state elections . <hl> <hl> Most also had ties to the cotton trade , so they were strong supporters of slavery . <hl>", "hl_sentences": "Most members of the middle class took a dim view of it , however , since it promoted a culture of leisure . Slavery stood as the antithesis of the middle-class view that dignity and respectability were achieved through work , and many members of this class became active in efforts to end it . Many northern elites worked hard to ensure the transmission of their inherited wealth from one generation to the next . Politically , they exercised considerable power in local and state elections . Most also had ties to the cotton trade , so they were strong supporters of slavery .", "question": { "cloze_format": "___ supported the abolition of slavery.", "normal_format": "Which of the following groups supported the abolition of slavery?", "question_choices": [ "northern business elites", "southern planter elites", "wage workers", "middle-class northerners" ], "question_id": "fs-idm333531552", "question_text": "Which of the following groups supported the abolition of slavery?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 0, "ans_text": "wage workers" }, "bloom": null, "hl_context": "<hl> Americana P . T . Barnum and the Feejee Mermaid The Connecticut native P . T . Barnum catered to the demand for escape and cheap amusements among the working class . <hl> <hl> His American Museum in New York City opened in 1841 and achieved great success . <hl> <hl> Millions flocked to see Barnum ’ s exhibits , which included a number of fantastic human and animal oddities , almost all of which were hoaxes . <hl> One exhibit in the 1840s featured the “ Feejee Mermaid , ” which Barnum presented as proof of the existence of the mythical mermaids of the deep ( Figure 9.18 ) . In truth , the mermaid was a half-monkey , half-fish stitched together . <hl> The Industrial Revolution in the United States created a new class of wage workers , and this working class also developed its own culture . <hl> They formed their own neighborhoods , living away from the oversight of bosses and managers . While industrialization and the market revolution brought some improvements to the lives of the working class , these sweeping changes did not benefit laborers as much as they did the middle class and the elites . The working class continued to live an often precarious existence . They suffered greatly during economic slumps , such as the Panic of 1819 .", "hl_sentences": "Americana P . T . Barnum and the Feejee Mermaid The Connecticut native P . T . Barnum catered to the demand for escape and cheap amusements among the working class . His American Museum in New York City opened in 1841 and achieved great success . Millions flocked to see Barnum ’ s exhibits , which included a number of fantastic human and animal oddities , almost all of which were hoaxes . The Industrial Revolution in the United States created a new class of wage workers , and this working class also developed its own culture .", "question": { "cloze_format": "___ were most drawn to amusements like P.T. Barnum's museum.", "normal_format": "Which social class was most drawn to amusements like P. T. Barnum’s museum?", "question_choices": [ "wage workers", "middle-class northerners", "southern planter elites", "northern business elites" ], "question_id": "fs-idm216364208", "question_text": "Which social class was most drawn to amusements like P. T. Barnum’s museum?" }, "references_are_paraphrase": 0 } ]
9
9.1 Early Industrialization in the Northeast Learning Objectives By the end of this section, you will be able to: Explain the role of the putting-out system in the rise of industrialization Understand industrialization’s impact on the nature of production and work Describe the effect of industrialization on consumption Identify the goals of workers’ organizations like the Working Men’s Party Northern industrialization expanded rapidly following the War of 1812. Industrialized manufacturing began in New England, where wealthy merchants built water-powered textile mills (and mill towns to support them) along the rivers of the Northeast. These mills introduced new modes of production centralized within the confines of the mill itself. As never before, production relied on mechanized sources with water power, and later steam, to provide the force necessary to drive machines. In addition to the mechanization and centralization of work in the mills, specialized, repetitive tasks assigned to wage laborers replaced earlier modes of handicraft production done by artisans at home. The operations of these mills irrevocably changed the nature of work by deskilling tasks, breaking down the process of production to its most basic, elemental parts. In return for their labor, the workers, who at first were young women from rural New England farming families, received wages. From its origin in New England, manufacturing soon spread to other regions of the United States. FROM ARTISANS TO WAGE WORKERS During the seventeenth and eighteenth centuries, artisans —skilled, experienced craft workers—produced goods by hand. The production of shoes provides a good example. In colonial times, people bought their shoes from master shoemakers, who achieved their status by living and working as apprentices under the rule of an older master artisan. An apprenticeship would be followed by work as a journeyman (a skilled worker without his own shop). After sufficient time as a journeyman, a shoemaker could at last set up his own shop as a master artisan. People came to the shop, usually attached to the back of the master artisan’s house, and there the shoemaker measured their feet in order to cut and stitch together an individualized product for each customer. In the late eighteenth and early nineteenth century, merchants in the Northeast and elsewhere turned their attention as never before to the benefits of using unskilled wage labor to make a greater profit by reducing labor costs. They used the putting-out system , which the British had employed at the beginning of their own Industrial Revolution, whereby they hired farming families to perform specific tasks in the production process for a set wage. In the case of shoes, for instance, American merchants hired one group of workers to cut soles into standardized sizes. A different group of families cut pieces of leather for the uppers, while still another was employed to stitch the standardized parts together. This process proved attractive because it whittled production costs. The families who participated in the putting-out system were not skilled artisans. They had not spent years learning and perfecting their craft and did not have ambitious journeymen to pay. Therefore, they could not demand—and did not receive—high wages. Most of the year they tended fields and orchards, ate the food that they produced, and sold the surplus. Putting-out work proved a welcome source of extra income for New England farm families who saw their profits dwindle from new competition from midwestern farms with higher-yield lands. Much of this part-time production was done under contract to merchants. Some farming families engaged in shoemaking (or shoe assemblage), as noted above. Many made brooms, plaited hats from straw or palm leaves (which merchants imported from Cuba and the West Indies), crafted furniture, made pottery, or wove baskets. Some, especially those who lived in Connecticut, made parts for clocks. The most common part-time occupation, however, was the manufacture of textiles. Farm women spun woolen thread and wove fabric. They also wove blankets, made rugs, and knit stockings. All this manufacturing took place on the farm, giving farmers and their wives control over the timing and pace of their labor. Their domestic productivity increased the quantity of goods available for sale in country towns and nearby cities. THE RISE OF MANUFACTURING In the late 1790s and early 1800s, Great Britain boasted the most advanced textile mills and machines in the world, and the United States continued to rely on Great Britain for finished goods. Great Britain hoped to maintain its economic advantage over its former colonies in North America. So, in an effort to prevent the knowledge of advanced manufacturing from leaving the Empire, the British banned the emigration of mechanics, skilled workers who knew how to build and repair the latest textile machines. Some skilled British mechanics, including Samuel Slater, managed to travel to the United States in the hopes of profiting from their knowledge and experience with advanced textile manufacturing. Slater ( Figure 9.3 ) understood the workings of the latest water-powered textile mills, which British industrialist Richard Arkwright had pioneered. In the 1790s in Pawtucket, Rhode Island, Slater convinced several American merchants, including the wealthy Providence industrialist Moses Brown, to finance and build a water-powered cotton mill based on the British models. Slater’s knowledge of both technology and mill organization made him the founder of the first truly successful cotton mill in the United States. The success of Slater and his partners Smith Brown and William Almy, relatives of Moses Brown, inspired others to build additional mills in Rhode Island and Massachusetts. By 1807, thirteen more mills had been established. President Jefferson’s embargo on British manufactured goods from late 1807 to early 1809 (discussed in a previous chapter) spurred more New England merchants to invest in industrial enterprises. By 1812, seventy-eight new textile mills had been built in rural New England towns. More than half turned out woolen goods, while the rest produced cotton cloth. Slater’s mills and those built in imitation of his were fairly small, employing only seventy people on average. Workers were organized the way that they had been in English factories, in family units. Under the “ Rhode Island system ,” families were hired. The father was placed in charge of the family unit, and he directed the labor of his wife and children. Instead of being paid in cash, the father was given “credit” equal to the extent of his family’s labor that could be redeemed in the form of rent (of company-owned housing) or goods from the company-owned store. The Embargo of 1807 and the War of 1812 played a pivotal role in spurring industrial development in the United States. Jefferson’s embargo prevented American merchants from engaging in the Atlantic trade, severely cutting into their profits. The War of 1812 further compounded the financial woes of American merchants. The acute economic problems led some New England merchants, including Francis Cabot Lowell, to cast their gaze on manufacturing. Lowell had toured English mills during a stay in Great Britain. He returned to Massachusetts having memorized the designs for the advanced textile machines he had seen in his travels, especially the power loom, which replaced individual hand weavers. Lowell convinced other wealthy merchant families to invest in the creation of new mill towns. In 1813, Lowell and these wealthy investors, known as the Boston Associates, created the Boston Manufacturing Company. Together they raised $400,000 and, in 1814, established a textile mill in Waltham and a second one in the same town shortly thereafter ( Figure 9.4 ). At Waltham, cotton was carded and drawn into coarse strands of cotton fibers called rovings. The rovings were then spun into yarn, and the yarn woven into cotton cloth. Yarn no longer had to be put out to farm families for further processing. All the work was now performed at a central location—the factory. The work in Lowell’s mills was both mechanized and specialized. Specialization meant the work was broken down into specific tasks, and workers repeatedly did the one task assigned to them in the course of a day. As machines took over labor from humans and people increasingly found themselves confined to the same repetitive step, the process of deskilling began. The Boston Associates’ mills, which each employed hundreds of workers, were located in company towns, where the factories and worker housing were owned by a single company. This gave the owners and their agents control over their workers. The most famous of these company towns was Lowell, Massachusetts. The new town was built on land the Boston Associates purchased in 1821 from the village of East Chelmsford at the falls of the Merrimack River, north of Boston. The mill buildings themselves were constructed of red brick with large windows to let in light. Company-owned boarding houses to shelter employees were constructed near the mills. The mill owners planted flowers and trees to maintain the appearance of a rural New England town and to forestall arguments, made by many, that factory work was unnatural and unwholesome. In contrast to many smaller mills, the Boston Associates’ enterprises avoided the Rhode Island system, preferring individual workers to families. These employees were not difficult to find. The competition New England farmers faced from farmers now settling in the West, and the growing scarcity of land in population-dense New England, had important implications for farmers’ children. Realizing their chances of inheriting a large farm or receiving a substantial dowry were remote, these teenagers sought other employment opportunities, often at the urging of their parents. While young men could work at a variety of occupations, young women had more limited options. The textile mills provided suitable employment for the daughters of Yankee farm families. Needing to reassure anxious parents that their daughters’ virtue would be protected and hoping to avoid what they viewed as the problems of industrialization—filth and vice—the Boston Associates established strict rules governing the lives of these young workers. The women lived in company-owned boarding houses to which they paid a portion of their wages. They woke early at the sound of a bell and worked a twelve-hour day during which talking was forbidden. They could not swear or drink alcohol, and they were required to attend church on Sunday. Overseers at the mills and boarding-house keepers kept a close eye on the young women’s behavior; workers who associated with people of questionable reputation or acted in ways that called their virtue into question lost their jobs and were evicted. Defining American Michel Chevalier on Mill Worker Rules and Wages In the 1830s, the French government sent engineer and economist Michel Chevalier to study industrial and financial affairs in Mexico and the United States. In 1839, he published Society, Manners, and Politics in the United States , in which he recorded his impressions of the Lowell textile mills. In the excerpt below, Chevalier describes the rules and wages of the Lawrence Company in 1833. All persons employed by the Company must devote themselves assiduously to their duty during working-hours. They must be capable of doing the work which they undertake, or use all their efforts to this effect. They must on all occasions, both in their words and in their actions, show that they are penetrated by a laudable love of temperance and virtue, and animated by a sense of their moral and social obligations. The Agent of the Company shall endeavour to set to all a good example in this respect. Every individual who shall be notoriously dissolute, idle, dishonest, or intemperate, who shall be in the practice of absenting himself from divine service, or shall violate the Sabbath, or shall be addicted to gaming, shall be dismissed from the service of the Company. . . . All ardent spirits are banished from the Company’s grounds, except when prescribed by a physician. All games of hazard and cards are prohibited within their limits and in the boarding-houses. Weekly wages were as follows: For picking and carding, $2.78 to $3.10 For spinning, $3.00 For weaving, $3.10 to $3.12 For warping and sizing, $3.45 to $4.00 For measuring and folding, $3.12 What kind of world were the factory owners trying to create with these rules? How do you think those who believed all White people were born free and equal would react to them? The mechanization of formerly handcrafted goods, and the removal of production from the home to the factory, dramatically increased output of goods. For example, in one nine-month period, the numerous Rhode Island women who spun yarn into cloth on hand looms in their homes produced a total of thirty-four thousand yards of fabrics of different types. In 1855, the women working in just one of Lowell’s mechanized mills produced more than forty-three thousand yards. The Boston Associates’ cotton mills quickly gained a competitive edge over the smaller mills established by Samuel Slater and those who had imitated him. Their success prompted the Boston Associates to expand. In Massachusetts, in addition to Lowell, they built new mill towns in Chicopee, Lawrence, and Holyoke. In New Hampshire, they built them in Manchester, Dover, and Nashua. And in Maine, they built a large mill in Saco on the Saco River. Other entrepreneurs copied them. By the time of the Civil War, 878 textile factories had been built in New England. All together, these factories employed more than 100,000 people and produced more than 940 million yards of cloth. Success in New England was repeated elsewhere. Small mills, more like those in Rhode Island than those in northern Massachusetts, New Hampshire, and Maine, were built in New York, Delaware, and Pennsylvania. By midcentury, three hundred textile mills were located in and near Philadelphia. Many produced specialty goods, such as silks and printed fabrics, and employed skilled workers, including people working in their own homes. Even in the South, the region that otherwise relied on slave labor to produce the very cotton that fed the northern factory movement, more than two hundred textile mills were built. Most textiles, however, continued to be produced in New England before the Civil War. Alongside the production of cotton and woolen cloth, which formed the backbone of the Industrial Revolution in the United States as in Britain, other crafts increasingly became mechanized and centralized in factories in the first half of the nineteenth century. Shoe making, leather tanning, papermaking, hat making, clock making, and gun making had all become mechanized to one degree or another by the time of the Civil War. Flour milling, because of the inventions of Oliver Evans ( Figure 9.5 ), had become almost completely automated and centralized by the early decades of the nineteenth century. So efficient were Evans-style mills that two employees were able to do work that had originally required five, and mills using Evans’s system spread throughout the mid-Atlantic states. THE RISE OF CONSUMERISM At the end of the eighteenth century, most American families lived in candlelit homes with bare floors and unadorned walls, cooked and warmed themselves over fireplaces, and owned few changes of clothing. All manufactured goods were made by hand and, as a result, were usually scarce and fairly expensive. The automation of the manufacturing process changed that, making consumer goods that had once been thought of as luxury items widely available for the first time. Now all but the very poor could afford the necessities and some of the small luxuries of life. Rooms were lit by oil lamps, which gave brighter light than candles. Homes were heated by parlor stoves, which allowed for more privacy; people no longer needed to huddle together around the hearth. Iron cookstoves with multiple burners made it possible for housewives to prepare more elaborate meals. Many people could afford carpets and upholstered furniture, and even farmers could decorate their homes with curtains and wallpaper. Clocks, which had once been quite expensive, were now within the reach of most ordinary people. THE WORK EXPERIENCE TRANSFORMED As production became mechanized and relocated to factories, the experience of workers underwent significant changes. Farmers and artisans had controlled the pace of their labor and the order in which things were done. If an artisan wanted to take the afternoon off, he could. If a farmer wished to rebuild his fence on Thursday instead of on Wednesday, he could. They conversed and often drank during the workday. Indeed, journeymen were often promised alcohol as part of their wages. One member of the group might be asked to read a book or a newspaper aloud to the others. In the warm weather, doors and windows might be opened to the outside, and work stopped when it was too dark to see. Work in factories proved to be quite different. Employees were expected to report at a certain time, usually early in the morning, and to work all day. They could not leave when they were tired or take breaks other than at designated times. Those who arrived late found their pay docked; five minutes’ tardiness could result in several hours’ worth of lost pay, and repeated tardiness could result in dismissal. The monotony of repetitive tasks made days particularly long. Hours varied according to the factory, but most factory employees toiled ten to twelve hours a day, six days a week. In the winter, when the sun set early, oil lamps were used to light the factory floor, and employees strained their eyes to see their work and coughed as the rooms filled with smoke from the lamps. In the spring, as the days began to grow longer, factories held “blowing-out” celebrations to mark the extinguishing of the oil lamps. These “blow-outs” often featured processions and dancing. Freedom within factories was limited. Drinking was prohibited. Some factories did not allow employees to sit down. Doors and windows were kept closed, especially in textile factories where fibers could be easily disturbed by incoming breezes, and mills were often unbearably hot and humid in the summer. In the winter, workers often shivered in the cold. In such environments, workers’ health suffered. The workplace posed other dangers as well. The presence of cotton bales alongside the oil used to lubricate machines made fire a common problem in textile factories. Workplace injuries were also common. Workers’ hands and fingers were maimed or severed when they were caught in machines; in some cases, their limbs or entire bodies were crushed. Workers who didn’t die from such injuries almost certainly lost their jobs, and with them, their income. Corporal punishment of both children and adults was common in factories; where abuse was most extreme, children sometimes died as a result of injuries suffered at the hands of an overseer. As the decades passed, working conditions deteriorated in many mills. Workers were assigned more machines to tend, and the owners increased the speed at which the machines operated. Wages were cut in many factories, and employees who had once labored for an hourly wage now found themselves reduced to piecework, paid for the amount they produced and not for the hours they toiled. Owners also reduced compensation for piecework. Low wages combined with regular periods of unemployment to make the lives of workers difficult, especially for those with families to support. In New York City in 1850, for example, the average male worker earned $300 a year; it cost approximately $600 a year to support a family of five. WORKERS AND THE LABOR MOVEMENT Many workers undoubtedly enjoyed some of the new wage opportunities factory work presented. For many of the young New England women who ran the machines in Waltham, Lowell, and elsewhere, the experience of being away from the family was exhilarating and provided a sense of solidarity among them. Though most sent a large portion of their wages home, having even a small amount of money of their own was a liberating experience, and many used their earnings to purchase clothes, ribbons, and other consumer goods for themselves. The long hours, strict discipline, and low wages, however, soon led workers to organize to protest their working conditions and pay. In 1821, the young women employed by the Boston Manufacturing Company in Waltham went on strike for two days when their wages were cut. In 1824, workers in Pawtucket struck to protest reduced pay rates and longer hours, the latter of which had been achieved by cutting back the amount of time allowed for meals. Similar strikes occurred at Lowell and in other mill towns like Dover, New Hampshire, where the women employed by the Cocheco Manufacturing Company ceased working in December 1828 after their wages were reduced. In the 1830s, female mill operatives in Lowell formed the Lowell Factory Girls Association to organize strike activities in the face of wage cuts ( Figure 9.6 ) and, later, established the Lowell Female Labor Reform Association to protest the twelve-hour workday. Even though strikes were rarely successful and workers usually were forced to accept reduced wages and increased hours, work stoppages as a form of labor protest represented the beginnings of the labor movement in the United States. Critics of industrialization blamed it for the increased concentration of wealth in the hands of the few: the factory owners made vast profits while the workers received only a small fraction of the revenue from what they produced. Under the labor theory of value , said critics, the value of a product should accurately reflect the labor needed to produce it. Profits from the sale of goods produced by workers should be distributed so laborers recovered in the form of wages the value their effort had added to the finished product. While factory owners, who contributed the workspace, the machinery, and the raw materials needed to create a product, should receive a share of the profits, their share should not be greater than the value of their contribution. Workers should thus receive a much larger portion of the profits than they currently did, and factory owners should receive less. In Philadelphia, New York, and Boston—all cities that experienced dizzying industrial growth during the nineteenth century—workers united to form political parties. Thomas Skidmore, from Connecticut, was the outspoken organizer of the Working Men’s Party , which lodged a radical protest against the exploitation of workers that accompanied industrialization. Skidmore took his cue from Thomas Paine and the American Revolution to challenge the growing inequity in the United States. He argued that inequality originated in the unequal distribution of property through inheritance laws. In his 1829 treatise, The Rights of Man to Property , Skidmore called for the abolition of inheritance and the redistribution of property. The Working Men’s Party also advocated the end of imprisonment for debt, a common practice whereby the debtor who could not pay was put in jail and his tools and property, if any, were confiscated. Skidmore’s vision of radical equality extended to all; women and men, no matter their race, should be allowed to vote and receive property, he believed. Skidmore died in 1832 when a cholera epidemic swept New York City, but the state of New York did away with imprisonment for debt in the same year. Worker activism became less common in the late 1840s and 1850s. As German and Irish immigrants poured into the United States in the decades preceding the Civil War, native-born laborers found themselves competing for jobs with new arrivals who were willing to work longer hours for less pay. In Lowell, Massachusetts, for example, the daughters of New England farmers encountered competition from the daughters of Irish farmers suffering the effects of the potato famine; these immigrant women were willing to work for far less and endure worse conditions than native-born women. Many of these native-born “daughters of freemen,” as they referred to themselves, left the factories and returned to their families. Not all wage workers had this luxury, however. Widows with children to support and girls from destitute families had no choice but to stay and accept the faster pace and lower pay. Male German and Irish immigrants competed with native-born men. Germans, many of whom were skilled workers, took jobs in furniture making. The Irish provided a ready source of unskilled labor needed to lay railroad track and dig canals. American men with families to support grudgingly accepted low wages in order to keep their jobs. As work became increasingly deskilled, no worker was irreplaceable, and no one’s job was safe. 9.2 A Vibrant Capitalist Republic Learning Objectives By the end of this section, you will be able to: Explain the process of selling western land Discuss the causes of the Panic of 1819 Identify key American innovators and inventors By the 1840s, the United States economy bore little resemblance to the import-and-export economy of colonial days. It was now a market economy, one in which the production of goods, and their prices, were unregulated by the government. Commercial centers, to which job seekers flocked, mushroomed. New York City’s population skyrocketed. In 1790, it was 33,000; by 1820, it had reached 200,000; and by 1825, it had swelled to 270,000. New opportunities for wealth appeared to be available to anyone. However, the expansion of the American economy made it prone to the boom-and-bust cycle. Market economies involve fluctuating prices for labor, raw materials, and consumer goods and depend on credit and financial instruments—any one of which can be the source of an imbalance and an economic downturn in which businesses and farmers default, wage workers lose their employment, and investors lose their assets. This happened for the first time in the United States in 1819, when waves of enthusiastic speculation (expectations of rapidly rising prices) in land and commodities gave way to drops in prices. THE LAND OFFICE BUSINESS In the early nineteenth century, people poured into the territories west of the long-settled eastern seaboard. Among them were speculators seeking to buy cheap parcels from the federal government in anticipation of a rise in prices. The Ohio Country in the Northwest Territory appeared to offer the best prospects for many in the East, especially New Englanders. The result was “Ohio fever,” as thousands traveled there to reap the benefits of settling in this newly available territory ( Figure 9.7 ). The federal government oversaw the orderly transfer of public land to citizens at public auctions. The Land Law of 1796 applied to the territory of Ohio after it had been wrested from Native people. Under this law, the United States would sell a minimum parcel of 640 acres for $2 an acre. The Land Law of 1800 further encouraged land sales in the Northwest Territory by reducing the minimum parcel size by half and enabling sales on credit, with the goal of stimulating settlement by ordinary farmers. The government created land offices to handle these sales and established them in the West within easy reach of prospective landowners. They could thus purchase land directly from the government, at the price the government had set. Buyers were given low interest rates, with payments that could be spread over four years. Surveyors marked off the parcels in straight lines, creating a landscape of checkerboard squares. The future looked bright for those who turned their gaze on the land in the West. Surveying, settling, and farming, turning the wilderness into a profitable commodity, gave purchasers a sense of progress. A uniquely American story of settling the land developed: hardy individuals wielding an axe cleared it, built a log cabin, and turned the frontier into a farm that paved the way for mills and towns ( Figure 9.8 ). My Story A New Englander Heads West A native of Vermont, Gershom Flagg was one of thousands of New Englanders who caught “Ohio fever.” In this letter to his brother, Azariah Flagg, dated August 3, 1817, he describes the hustle and bustle of the emerging commercial town of Cincinnati. DEAR BROTHER, Cincinnati is an incorporated City. It contained in 1815, 1,100 buildings of different descriptions among which are above 20 of Stone 250 of brick & 800 of Wood. The population in 1815 was 6,500. There are about 60 Mercantile stores several of which are wholesale. Here are a great share of Mechanics of all kinds. Here is one Woolen Factory four Cotton factories but not now in operation. A most stupendously large building of Stone is likewise erected immediately on the bank of the River for a steam Mill. It is nine stories high at the Waters edge & is 87 by 62 feet. It drives four pair of Stones besides various other Machinery as Wool carding &c &c. There is also a valuable Steam Saw Mill driving four saws also an inclined Wheel ox Saw Mill with two saws, one Glass Factory. The town is Rapidly increasing in Wealth & population. Here is a Branch of the United States Bank and three other banks & two Printing offices. The country around is rich. . . . That you may all be prospered in the world is the anxious wish of your affectionate Brother GERSHOM FLAGG What caught Flagg’s attention? From your reading of this letter and study of the engraving below ( Figure 9.9 ), what impression can you take away of Cincinnati in 1817? THE PANIC OF 1819 The first major economic crisis in the United States after the War of 1812 was due, in large measure, to factors in the larger Atlantic economy. It was made worse, however, by land speculation and poor banking practices at home. British textile mills voraciously consumed American cotton, and the devastation of the Napoleonic Wars made Europe reliant on other American agricultural commodities such as wheat. This drove up both the price of American agricultural products and the value of the land on which staples such as cotton, wheat, corn, and tobacco were grown. Many Americans were struck with “ land fever .” Farmers strove to expand their acreage, and those who lived in areas where unoccupied land was scarce sought holdings in the West. They needed money to purchase this land, however. Small merchants and factory owners, hoping to take advantage of this boom time, also sought to borrow money to expand their businesses. When existing banks refused to lend money to small farmers and others without a credit history, state legislatures chartered new banks to meet the demand. In one legislative session, Kentucky chartered forty-six. As loans increased, paper money from new state banks flooded the country, creating inflation that drove the price of land and goods still higher. This, in turn, encouraged even more people to borrow money with which to purchase land or to expand or start their own businesses. Speculators took advantage of this boom in the sale of land by purchasing property not to live on, but to buy cheaply and resell at exorbitant prices. During the War of 1812, the Bank of the United States had suspended payments in specie , “hard money” usually in the form of gold and silver coins. When the war ended, the bank continued to issue only paper banknotes and to redeem notes issued by state banks with paper only. The newly chartered banks also adopted this practice, issuing banknotes in excess of the amount of specie in their vaults. This shaky economic scheme worked only so long as people were content to conduct business with paper money and refrain from demanding that banks instead give them the gold and silver that was supposed to back it. If large numbers of people, or banks that had loaned money to other banks, began to demand specie payments, the banking system would collapse, because there was no longer enough specie to support the amount of paper money the banks had put into circulation. So terrified were bankers that customers would demand gold and silver that an irate bank employee in Ohio stabbed a customer who had the audacity to ask for specie in exchange for the banknotes he held. In an effort to bring stability to the nation’s banking system, Congress chartered the Second Bank of the United States (a revival of Alexander Hamilton’s national bank) in 1816. But this new institution only compounded the problem by making risky loans, opening branches in the South and West where land fever was highest, and issuing a steady stream of Bank of the United States notes, a move that increased inflation and speculation. The inflated economic bubble burst in 1819, resulting in a prolonged economic depression or severe downturn in the economy called the Panic of 1819. It was the first economic depression experienced by the American public, who panicked as they saw the prices of agricultural products fall and businesses fail. Prices had already begun falling in 1815, at the end of the Napoleonic Wars, when Britain began to “dump” its surplus manufactured goods, the result of wartime overproduction, in American ports, where they were sold for low prices and competed with American-manufactured goods. In 1818, to make the economic situation worse, prices for American agricultural products began to fall both in the United States and in Europe; the overproduction of staples such as wheat and cotton coincided with the recovery of European agriculture, which reduced demand for American crops. Crop prices tumbled by as much 75 percent. This dramatic decrease in the value of agricultural goods left farmers unable to pay their debts. As they defaulted on their loans, banks seized their property. However, because the drastic fall in agricultural prices had greatly reduced the value of land, the banks were left with farms they were unable to sell. Land speculators lost the value of their investments. As the countryside suffered, hard-hit farmers ceased to purchase manufactured goods. Factories responded by cutting wages or firing employees. In 1818, the Second Bank of the United States needed specie to pay foreign investors who had loaned money to the United States to enable the country to purchase Louisiana. The bank began to call in the loans it had made and required that state banks pay their debts in gold and silver. State banks that could not collect loan payments from hard-pressed farmers could not, in turn, meet their obligations to the Second Bank of the United States. Severe consequences followed as banks closed their doors and businesses failed. Three-quarters of the work force in Philadelphia was unemployed, and charities were swamped by thousands of newly destitute people needing assistance. In states with imprisonment for debt, the prison population swelled. As a result, many states drafted laws to provide relief for debtors. Even those at the top of the social ladder were affected by the Panic of 1819. Thomas Jefferson, who had cosigned a loan for a friend, nearly lost Monticello when his acquaintance defaulted, leaving Jefferson responsible for the debt. In an effort to stimulate the economy in the midst of the economic depression, Congress passed several acts modifying land sales. The Land Law of 1820 lowered the price of land to $1.25 per acre and allowed small parcels of eighty acres to be sold. The Relief Act of 1821 allowed Ohioans to return land to the government if they could not afford to keep it. The money they received in return was credited toward their debt. The act also extended the credit period to eight years. States, too, attempted to aid those faced with economic hard times by passing laws to prevent mortgage foreclosures so buyers could keep their homes. Americans made the best of the opportunities presented in business, in farming, or on the frontier, and by 1823 the Panic of 1819 had ended. The recovery provided ample evidence of the vibrant and resilient nature of the American people. ENTREPRENEURS AND INVENTORS The volatility of the U.S. economy did nothing to dampen the creative energies of its citizens in the years before the Civil War. In the 1800s, a frenzy of entrepreneurship and invention yielded many new products and machines. The republic seemed to be a laboratory of innovation, and technological advances appeared unlimited. One of the most influential advancements of the early nineteenth century was the cotton engine or gin, invented by Eli Whitney and patented in 1794. Whitney, who was born in Massachusetts, had spent time in the South and knew that a device to speed up the production of cotton was desperately needed so cotton farmers could meet the growing demand for their crop. He hoped the cotton gin would render slavery obsolete. Whitney’s seemingly simple invention cleaned the seeds from the raw cotton far more quickly and efficiently than could enslaved workers by hand ( Figure 9.10 ). The raw cotton with seeds was placed in the cotton gin, and with the use of a hand crank, the seeds were extracted through a carding device that aligned the cotton fibers in strands for spinning. Whitney also worked on machine tools , devices that cut and shaped metal to make standardized, interchangeable parts for other mechanical devices like clocks and guns. Whitney’s machine tools to manufacture parts for muskets enabled guns to be manufactured and repaired by people other than skilled gunsmiths. His creative genius served as a source of inspiration for many other American inventors. Another influential new technology of the early 1800s was the steamship engine, invented by Robert Fulton in 1807. Fulton’s first steamship, the Clermont , used paddle wheels to travel the 150 miles from New York City to Albany in a record time of only thirty-two hours ( Figure 9.11 ). Soon, a fleet of steamboats was traversing the Hudson River and New York Harbor, later expanding to travel every major American river including the mighty Mississippi. By the 1830s there were over one thousand of these vessels, radically changing water transportation by ending its dependence on the wind. Steamboats could travel faster and more cheaply than sailing vessels or keelboats, which floated downriver and had to be poled or towed upriver on the return voyage. Steamboats also arrived with much greater dependability. The steamboat facilitated the rapid economic development of the massive Mississippi River Valley and the settlement of the West. Virginia-born Cyrus McCormick wanted to replace the laborious process of using a scythe to cut and gather wheat for harvest. In 1831, he and the enslaved workers on his family’s plantation tested a horse-drawn mechanical reaper, and over the next several decades, he made constant improvements to it ( Figure 9.12 ). More farmers began using it in the 1840s, and greater demand for the McCormick reaper led McCormick and his brother to establish the McCormick Harvesting Machine Company in Chicago, where labor was more readily available. By the 1850s, McCormick’s mechanical reaper had enabled farmers to vastly increase their output. McCormick—and also John Deere, who improved on the design of plows—opened the prairies to agriculture. McCormick’s bigger machine could harvest grain faster, and Deere’s plow could cut through the thick prairie sod. Agriculture north of the Ohio River became the pantry that would lower food prices and feed the major cities in the East. In short order, Ohio, Indiana, and Illinois all become major agricultural states. Samuel Morse added the telegraph to the list of American innovations introduced in the years before the Civil War. Born in Massachusetts in 1791, Morse first gained renown as a painter before turning his attention to the development of a method of rapid communication in the 1830s. In 1838, he gave the first public demonstration of his method of conveying electric pulses over a wire, using the basis of what became known as Morse code. In 1843, Congress agreed to help fund the new technology by allocating $30,000 for a telegraph line to connect Washington, DC, and Baltimore along the route of the Baltimore and Ohio Railroad. In 1844, Morse sent the first telegraph message on the new link. Improved communication systems fostered the development of business, economics, and politics by allowing for dissemination of news at a speed previously unknown. 9.3 On the Move: The Transportation Revolution Learning Objectives By the end of this section, you will be able to: Describe the development of improved methods of nineteenth-century domestic transportation Identify the ways in which roads, canals, and railroads impacted Americans’ lives in the nineteenth century Americans in the early 1800s were a people on the move, as thousands left the eastern coastal states for opportunities in the West. Unlike their predecessors, who traveled by foot or wagon train, these settlers had new transport options. Their trek was made possible by the construction of roads, canals, and railroads, projects that required the funding of the federal government and the states. New technologies, like the steamship and railroad lines, had brought about what historians call the transportation revolution. States competed for the honor of having the most advanced transport systems. People celebrated the transformation of the wilderness into an orderly world of improvement demonstrating the steady march of progress and the greatness of the republic. In 1817, John C. Calhoun of South Carolina looked to a future of rapid internal improvements, declaring, “Let us . . . bind the Republic together with a perfect system of roads and canals.” Americans agreed that internal transportation routes would promote progress. By the eve of the Civil War, the United States had moved beyond roads and canals to a well-established and extensive system of railroads. ROADS AND CANALS One key part of the transportation revolution was the widespread building of roads and turnpikes. In 1811, construction began on the Cumberland Road , a national highway that provided thousands with a route from Maryland to Illinois. The federal government funded this important artery to the West, beginning the creation of a transportation infrastructure for the benefit of settlers and farmers. Other entities built turnpikes, which (as today) charged fees for use. New York State, for instance, chartered turnpike companies that dramatically increased the miles of state roads from one thousand in 1810 to four thousand by 1820. New York led the way in building turnpikes. Canal mania swept the United States in the first half of the nineteenth century. Promoters knew these artificial rivers could save travelers immense amounts of time and money. Even short waterways, such as the two-and-a-half-mile canal going around the rapids of the Ohio River near Louisville, Kentucky, proved a huge leap forward, in this case by opening a water route from Pittsburgh to New Orleans. The preeminent example was the Erie Canal ( Figure 9.13 ), which linked the Hudson River, and thus New York City and the Atlantic seaboard, to the Great Lakes and the Mississippi River Valley. With its central location, large harbor, and access to the hinterland via the Hudson River, New York City already commanded the lion’s share of commerce. Still, the city’s merchants worried about losing ground to their competitors in Philadelphia and Baltimore. Their search for commercial advantage led to the dream of creating a water highway connecting the city’s Hudson River to Lake Erie and markets in the West. The result was the Erie Canal. Chartered in 1817 by the state of New York, the canal took seven years to complete. When it opened in 1825, it dramatically decreased the cost of shipping while reducing the time to travel to the West. Soon $15 million worth of goods (more than $200 million in today’s money) was being transported on the 363-mile waterway every year. The success of the Erie Canal led to other, similar projects. The Wabash and Erie Canal, which opened in the early 1840s, stretched over 450 miles, making it the longest canal in North America ( Figure 9.14 ). Canals added immensely to the country’s sense of progress. Indeed, they appeared to be the logical next step in the process of transforming wilderness into civilization. As with highway projects such as the Cumberland Road, many canals were federally sponsored, especially during the presidency of John Quincy Adams in the late 1820s. Adams, along with Secretary of State Henry Clay, championed what was known as the American System, part of which included plans for a broad range of internal transportation improvements. Adams endorsed the creation of roads and canals to facilitate commerce and develop markets for agriculture as well as to advance settlement in the West. RAILROADS Starting in the late 1820s, steam locomotives began to compete with horse-drawn locomotives. The railroads with steam locomotives offered a new mode of transportation that fascinated citizens, buoying their optimistic view of the possibilities of technological progress. The Mohawk and Hudson Railroad was the first to begin service with a steam locomotive. Its inaugural train ran in 1831 on a track outside Albany and covered twelve miles in twenty-five minutes. Soon it was traveling regularly between Albany and Schenectady. Toward the middle of the century, railroad construction kicked into high gear, and eager investors quickly formed a number of railroad companies. As a railroad grid began to take shape, it stimulated a greater demand for coal, iron, and steel. Soon, both railroads and canals crisscrossed the states ( Figure 9.15 ), providing a transportation infrastructure that fueled the growth of American commerce. Indeed, the transportation revolution led to development in the coal, iron, and steel industries, providing many Americans with new job opportunities. AMERICANS ON THE MOVE The expansion of roads, canals, and railroads changed people’s lives. In 1786, it had taken a minimum of four days to travel from Boston, Massachusetts, to Providence, Rhode Island. By 1840, the trip took half a day on a train. In the twenty-first century, this may seem intolerably slow, but people at the time were amazed by the railroad’s speed. Its average of twenty miles per hour was twice as fast as other available modes of transportation. By 1840, more than three thousand miles of canals had been dug in the United States, and thirty thousand miles of railroad track had been laid by the beginning of the Civil War. Together with the hundreds of steamboats that plied American rivers, these advances in transportation made it easier and less expensive to ship agricultural products from the West to feed people in eastern cities, and to send manufactured goods from the East to people in the West. Without this ability to transport goods, the market revolution would not have been possible. Rural families also became less isolated as a result of the transportation revolution. Traveling circuses, menageries, peddlers, and itinerant painters could now more easily make their way into rural districts, and people in search of work found cities and mill towns within their reach. 9.4 A New Social Order: Class Divisions Learning Objectives By the end of this section, you will be able to: Identify the shared perceptions and ideals of each social class Assess different social classes’ views of slavery The profound economic changes sweeping the United States led to equally important social and cultural transformations. The formation of distinct classes, especially in the rapidly industrializing North, was one of the most striking developments. The unequal distribution of newly created wealth spurred new divisions along class lines. Each class had its own specific culture and views on the issue of slavery. THE ECONOMIC ELITE Economic elites gained further social and political ascendance in the United States due to a fast-growing economy that enhanced their wealth and allowed distinctive social and cultural characteristics to develop among different economic groups. In the major northern cities of Boston, New York, and Philadelphia, leading merchants formed an industrial capitalist elite. Many came from families that had been deeply engaged in colonial trade in tea, sugar, pepper, enslaved Africans, and other commodities and that were familiar with trade networks connecting the United States with Europe, the West Indies, and the Far East. These colonial merchants had passed their wealth to their children. After the War of 1812, the new generation of merchants expanded their economic activities. They began to specialize in specific types of industry, spearheading the development of industrial capitalism based on factories they owned and on specific commercial services such as banking, insurance, and shipping. Junius Spencer Morgan ( Figure 9.16 ), for example, rose to prominence as a banker. His success began in Boston, where he worked in the import business in the 1830s. He then formed a partnership with a London banker, George Peabody, and created Peabody, Morgan & Co. In 1864, he renamed the enterprise J. S. Morgan & Co. His son, J. P. Morgan, became a noted financier in the later nineteenth and early twentieth century. Members of the northern business elite forged close ties with each other to protect and expand their economic interests. Marriages between leading families formed a crucial strategy to advance economic advantage, and the homes of the northern elite became important venues for solidifying social bonds. Exclusive neighborhoods started to develop as the wealthy distanced themselves from the poorer urban residents, and cities soon became segregated by class. Industrial elites created chambers of commerce to advance their interests; by 1858 there were ten in the United States. These networking organizations allowed top bankers and merchants to stay current on the economic activities of their peers and further strengthen the bonds among themselves. The elite also established social clubs to forge and maintain ties. The first of these, the Philadelphia Club, came into being in 1834. Similar clubs soon formed in other cities and hosted a range of social activities designed to further bind together the leading economic families. Many northern elites worked hard to ensure the transmission of their inherited wealth from one generation to the next. Politically, they exercised considerable power in local and state elections. Most also had ties to the cotton trade, so they were strong supporters of slavery. The Industrial Revolution led some former artisans to reinvent themselves as manufacturers. These enterprising leaders of manufacturing differed from the established commercial elite in the North and South because they did not inherit wealth. Instead, many came from very humble working-class origins and embodied the dream of achieving upward social mobility through hard work and discipline. As the beneficiaries of the economic transformations sweeping the republic, these newly established manufacturers formed a new economic elite that thrived in the cities and cultivated its own distinct sensibilities. They created a culture that celebrated hard work, a position that put them at odds with southern planter elites who prized leisure and with other elite northerners who had largely inherited their wealth and status. Peter Cooper provides one example of the new northern manufacturing class. Ever inventive, Cooper dabbled in many different moneymaking enterprises before gaining success in the glue business. He opened his Manhattan glue factory in the 1820s and was soon using his profits to expand into a host of other activities, including iron production. One of his innovations was the steam locomotive, which he invented in 1827 ( Figure 9.17 ). Despite becoming one of the wealthiest men in New York City, Cooper lived simply. Rather than buying an ornate bed, for example, he built his own. He believed respectability came through hard work, not family pedigree. Those who had inherited their wealth derided self-made men like Cooper, and he and others like him were excluded from the social clubs established by the merchant and financial elite of New York City. Self-made northern manufacturers, however, created their own organizations that aimed to promote upward mobility. The Providence Association of Mechanics and Manufacturers was formed in 1789 and promoted both industrial arts and education as a pathway to economic success. In 1859, Peter Cooper established the Cooper Union for the Advancement of Science and Art, a school in New York City dedicated to providing education in technology. Merit, not wealth, mattered most according to Cooper, and admission to the school was based solely on ability; race, sex, and family connections had no place. The best and brightest could attend Cooper Union tuition-free, a policy that remained in place until 2014. THE MIDDLE CLASS Not all enterprising artisans were so successful that they could rise to the level of the elite. However, many artisans and small merchants, who owned small factories and stores, did manage to achieve and maintain respectability in an emerging middle class. Lacking the protection of great wealth, members of the middle class agonized over the fear that they might slip into the ranks of wage laborers; thus they strove to maintain or improve their middle-class status and that of their children. To this end, the middle class valued cleanliness, discipline, morality, hard work, education, and good manners. Hard work and education enabled them to rise in life. Middle-class children, therefore, did not work in factories. Instead they attended school and in their free time engaged in “self-improving” activities, such as reading or playing the piano, or they played with toys and games that would teach them the skills and values they needed to succeed in life. In the early nineteenth century, members of the middle class began to limit the number of children they had. Children no longer contributed economically to the household, and raising them “correctly” required money and attention. It therefore made sense to have fewer of them. Middle-class women did not work for wages. Their job was to care for the children and to keep the house in a state of order and cleanliness, often with the help of a servant. They also performed the important tasks of cultivating good manners among their children and their husbands and of purchasing consumer goods; both activities proclaimed to neighbors and prospective business partners that their families were educated, cultured, and financially successful. Northern business elites, many of whom owned or had invested in businesses like cotton mills that profited from slave labor, often viewed the institution of slavery with ambivalence. Most members of the middle class took a dim view of it, however, since it promoted a culture of leisure. Slavery stood as the antithesis of the middle-class view that dignity and respectability were achieved through work, and many members of this class became active in efforts to end it. This class of upwardly mobile citizens promoted temperance, or abstinence from alcohol. They also gave their support to Protestant ministers like Charles Grandison Finney, who preached that all people possessed free moral agency , meaning they could change their lives and bring about their own salvation, a message that resonated with members of the middle class, who already believed their worldly efforts had led to their economic success. THE WORKING CLASS The Industrial Revolution in the United States created a new class of wage workers, and this working class also developed its own culture. They formed their own neighborhoods, living away from the oversight of bosses and managers. While industrialization and the market revolution brought some improvements to the lives of the working class, these sweeping changes did not benefit laborers as much as they did the middle class and the elites. The working class continued to live an often precarious existence. They suffered greatly during economic slumps, such as the Panic of 1819. Although most working-class men sought to emulate the middle class by keeping their wives and children out of the work force, their economic situation often necessitated that others besides the male head of the family contribute to its support. Thus, working-class children might attend school for a few years or learn to read and write at Sunday school, but education was sacrificed when income was needed, and many working-class children went to work in factories. While the wives of wage laborers usually did not work for wages outside the home, many took in laundry or did piecework at home to supplement the family’s income. Although the urban working class could not afford the consumer goods that the middle class could, its members did exercise a great deal of influence over popular culture. Theirs was a festive public culture of release and escape from the drudgery of factory work, catered to by the likes of Phineas Taylor Barnum, the celebrated circus promoter and showman. Taverns also served an important function as places to forget the long hours and uncertain wages of the factories. Alcohol consumption was high among the working class, although many workers did take part in the temperance movement. It is little wonder that middle-class manufacturers attempted to abolish alcohol. Americana P. T. Barnum and the Feejee Mermaid The Connecticut native P. T. Barnum catered to the demand for escape and cheap amusements among the working class. His American Museum in New York City opened in 1841 and achieved great success. Millions flocked to see Barnum’s exhibits, which included a number of fantastic human and animal oddities, almost all of which were hoaxes. One exhibit in the 1840s featured the “Feejee Mermaid,” which Barnum presented as proof of the existence of the mythical mermaids of the deep ( Figure 9.18 ). In truth, the mermaid was a half-monkey, half-fish stitched together. Wage workers in the North were largely hostile to the abolition of slavery, fearing it would unleash more competition for jobs from free Black people. Many were also hostile to immigration. The pace of immigration to the United States accelerated in the 1840s and 1850s as Europeans were drawn to the promise of employment and land in the United States. Many new members of the working class came from the ranks of these immigrants, who brought new foods, customs, and religions. The Roman Catholic population of the United States, fairly small before this period, began to swell with the arrival of the Irish and the Germans.
u.s._history
Summary 14.1 The Compromise of 1850 The difficult process of reaching a compromise on slavery in 1850 exposed the sectional fault lines in the United States. After several months of rancorous debate, Congress passed five laws—known collectively as the Compromise of 1850—that people on both sides of the divide hoped had solved the nation’s problems. However, many northerners feared the impact of the Fugitive Slave Act, which made it a crime not only to help enslaved people escape, but also to fail to help capture them. Many Americans, both Black and White, flouted the Fugitive Slave Act by participating in the Underground Railroad, providing safe houses for slaves on the run from the South. Eight northern states passed personal liberty laws to counteract the effects of the Fugitive Slave Act. 14.2 The Kansas-Nebraska Act and the Republican Party The application of popular sovereignty to the organization of the Kansas and Nebraska territories ended the sectional truce that had prevailed since the Compromise of 1850. Senator Douglas’s Kansas-Nebraska Act opened the door to chaos in Kansas as proslavery and Free-Soil forces waged war against each other, and radical abolitionists, notably John Brown, committed themselves to violence to end slavery. The act also upended the second party system of Whigs and Democrats by inspiring the formation of the new Republican Party, committed to arresting the further spread of slavery. Many voters approved its platform in the 1856 presidential election, though the Democrats won the race because they remained a national, rather than a sectional, political force. 14.3 The Dred Scott Decision and Sectional Strife The Dred Scott decision of 1857 went well beyond the question of whether or not Dred Scott gained his freedom. Instead, the Supreme Court delivered a far-reaching pronouncement about African Americans in the United States, finding they could never be citizens and that Congress could not interfere with the expansion of slavery into the territories. Republicans erupted in anger at this decision, which rendered their party’s central platform unconstitutional. Abraham Lincoln fully articulated the Republican position on the issue of slavery in his 1858 debates with Senator Stephen Douglas. By the end of that year, Lincoln had become a nationally known Republican icon. For the Democrats’ part, unity within their party frayed over both the Dred Scott case and the Freeport Doctrine, undermining the Democrats’ future ability to retain control of the presidency. 14.4 John Brown and the Election of 1860 A new level of animosity and distrust emerged in 1859 in the aftermath of John Brown’s raid. The South exploded in rage at the northern celebration of Brown as a heroic freedom fighter. Fire-Eaters called openly for disunion. Poisoned relations split the Democrats into northern and southern factions, a boon to the Republican candidate Lincoln. His election triggered the downfall of the American experiment with democracy as southern states began to leave the Union.
Chapter Outline 14.1 The Compromise of 1850 14.2 The Kansas-Nebraska Act and the Republican Party 14.3 The Dred Scott Decision and Sectional Strife 14.4 John Brown and the Election of 1860 Introduction The heated sectional controversy between the North and the South reached new levels of intensity in the 1850s. Southerners and northerners grew ever more antagonistic as they debated the expansion of slavery in the West. The notorious confrontation between Representative Preston Brooks of South Carolina and Massachusetts senator Charles Sumner depicted in the image above ( Figure 14.1 ), illustrates the contempt between extremists on both sides. The “Caning of Sumner” in May 1856 followed upon a speech given by Sumner two days earlier in which he condemned slavery in no uncertain terms, declaring: “[Admitting Kansas as a slave state] is the rape of a virgin territory, compelling it to the hateful embrace of slavery; and it may be clearly traced to a depraved longing for a new slave state, the hideous offspring of such a crime, in the hope of adding to the power of slavery in the national government.” Sumner criticized proslavery legislators, particularly attacking a fellow senator and relative of Preston Brooks. Brooks responded by beating Sumner with a cane, a thrashing that southerners celebrated as a manly defense of gentlemanly honor and their way of life. The episode highlights the violent clash between pro- and antislavery factions in the 1850s, a conflict that would eventually lead to the traumatic unraveling of American democracy and civil war.
[ { "answer": { "ans_choice": 0, "ans_text": "A" }, "bloom": null, "hl_context": "<hl> As president , Taylor sought to defuse the sectional controversy as much as possible , and , above all else , to preserve the Union . <hl> Although Taylor was born in Virginia before relocating to Kentucky and enslaved more than one hundred people by the late 1840s , he did not push for slavery ’ s expansion into the Mexican Cession . However , the California Gold Rush made California ’ s statehood into an issue demanding immediate attention . In 1849 , after California residents adopted a state constitution prohibiting slavery , President Taylor called on Congress to admit California and New Mexico as free states , a move that infuriated southern defenders of slavery who argued for the right to bring their enslaved property wherever they chose . Taylor , who did not believe slavery could flourish in the arid lands of the Mexican Cession because the climate prohibited plantation-style farming , proposed that the Wilmot Proviso be applied to the entire area .", "hl_sentences": "As president , Taylor sought to defuse the sectional controversy as much as possible , and , above all else , to preserve the Union .", "question": { "cloze_format": "President Zachary Taylor's top priority was ___.", "normal_format": "What was President Zachary Taylor’s top priority as president?", "question_choices": [ "preserving the Union", "ensuring the recapture of escaped enslaved people", "expanding slavery", "enlarging the state of Texas" ], "question_id": "fs-idp72446960", "question_text": "What was President Zachary Taylor’s top priority as president?" }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 1, "ans_text": "the admission of Kansas as a free state" }, "bloom": null, "hl_context": "In the end , Clay stepped down as leader of the compromise effort in frustration , and Illinois senator Stephen Douglas pushed five separate bills through Congress , collectively composing the Compromise of 1850 . <hl> First , as advocated by the South , Congress passed the Fugitive Slave Act , a law that provided federal money — or “ bounties ” — to slave-catchers . <hl> <hl> Second , to balance this concession to the South , Congress admitted California as a free state , a move that cheered antislavery advocates and abolitionists in the North . <hl> Third , Congress settled the contested boundary between New Mexico and Texas by favoring New Mexico and not allowing for an enlarged Texas , another outcome pleasing to the North . <hl> In return , the federal government paid the debts Texas had incurred as an independent republic . <hl> <hl> Fourth , antislavery advocates welcomed Congress ’ s ban on the slave trade in Washington , DC , although slavery continued to thrive in the nation ’ s capital . <hl> Finally , on the thorny issue of whether slavery would expand into the territories , Congress avoided making a direct decision and instead relied on the principle of popular sovereignty . This put the onus on residents of the territories to decide for themselves whether to allow slavery . Popular sovereignty followed the logic of American democracy ; majorities in each territory would decide the territory ’ s laws . The compromise , however , further exposed the sectional divide as votes on the bills divided along strict regional lines . Most Americans breathed a sigh of relief over the deal brokered in 1850 , choosing to believe it had saved the Union . Rather than resolving divisions between the North and the South , however , the compromise stood as a truce in an otherwise white-hot sectional conflict . Tensions in the nation remained extremely high ; indeed , southerners held several conventions after the compromise to discuss ways to protect the South . At these meetings , extremists who called for secession found themselves in the minority , since most southerners committed themselves to staying in the Union — but only if slavery remained in the states where it already existed , and if no effort was made to block its expansion into areas where citizens wanted it , thereby applying the idea of popular sovereignty ( Figure 14.5 ) . In Congress , Kentucky senator Henry Clay , a veteran of congressional conflicts , offered a series of resolutions addressing the list of issues related to slavery and its expansion . <hl> Clay ’ s resolutions called for the admission of California as a free state ; no restrictions on slavery in the rest of the Mexican Cession ( a rejection of the Wilmot Proviso and the Free-Soil Party ’ s position ); a boundary between New Mexico and Texas that did not expand Texas ( an important matter , since Texas allowed slavery and a larger Texas meant more opportunities for the expansion of slavery ); payment of outstanding Texas debts from the Lone Star Republic days ; and the end of the slave trade ( but not of slavery ) in the nation ’ s capital , coupled with a more robust federal fugitive slave law . <hl> Clay presented these proposals as an omnibus bill , that is , one that would be voted on its totality .", "hl_sentences": "First , as advocated by the South , Congress passed the Fugitive Slave Act , a law that provided federal money — or “ bounties ” — to slave-catchers . Second , to balance this concession to the South , Congress admitted California as a free state , a move that cheered antislavery advocates and abolitionists in the North . In return , the federal government paid the debts Texas had incurred as an independent republic . Fourth , antislavery advocates welcomed Congress ’ s ban on the slave trade in Washington , DC , although slavery continued to thrive in the nation ’ s capital . Clay ’ s resolutions called for the admission of California as a free state ; no restrictions on slavery in the rest of the Mexican Cession ( a rejection of the Wilmot Proviso and the Free-Soil Party ’ s position ); a boundary between New Mexico and Texas that did not expand Texas ( an important matter , since Texas allowed slavery and a larger Texas meant more opportunities for the expansion of slavery ); payment of outstanding Texas debts from the Lone Star Republic days ; and the end of the slave trade ( but not of slavery ) in the nation ’ s capital , coupled with a more robust federal fugitive slave law .", "question": { "cloze_format": "___ was not a component of the Compromise of 1850.", "normal_format": "Which of the following was not a component of the Compromise of 1850?", "question_choices": [ "the passage of the Fugitive Slave Act", "the admission of Kansas as a free state", "the admission of California as a free state", "a ban on the slave trade in Washington, DC" ], "question_id": "fs-idp57768016", "question_text": "Which of the following was not a component of the Compromise of 1850?" }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 3, "ans_text": "halting the spread of slavery" }, "bloom": null, "hl_context": "<hl> The new Republican Party pledged itself to preventing the spread of slavery into the territories and railed against the Slave Power , infuriating the South . <hl> As a result , the party became a solidly northern political organization . As never before , the U . S . political system was polarized along sectional fault lines .", "hl_sentences": "The new Republican Party pledged itself to preventing the spread of slavery into the territories and railed against the Slave Power , infuriating the South .", "question": { "cloze_format": "____ was a focus of the new Republican Party.", "normal_format": "Which of the following was a focus of the new Republican Party?", "question_choices": [ "supporting Irish Catholic immigration", "encouraging the use of popular sovereignty to determine where slavery could exist", "promoting states’ rights", "halting the spread of slavery" ], "question_id": "fs-idp106550800", "question_text": "Which of the following was a focus of the new Republican Party?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 1, "ans_text": "B" }, "bloom": null, "hl_context": "In 1855 and 1856 , pro - and antislavery activists flooded Kansas with the intention of influencing the popular-sovereignty rule of the territories . <hl> Proslavery Missourians who crossed the border to vote in Kansas became known as border ruffians ; these gained the advantage by winning the territorial elections , most likely through voter fraud and illegal vote counting . <hl> ( By some estimates , up to 60 percent of the votes cast in Kansas were fraudulent . ) Once in power , the proslavery legislature , meeting at Lecompton , Kansas , drafted a proslavery constitution known as the Lecompton Constitution . It was supported by President Buchanan , but opposed by Democratic Senator Stephen A . Douglas of Illinois . Defining American The Lecompton Constitution Kansas was home to no fewer than four state constitutions in its early years . Its first constitution , the Topeka Constitution , would have made Kansas a free-soil state . A proslavery legislature , however , created the 1857 Lecompton Constitution to enshrine the institution of slavery in the new Kansas-Nebraska territories . In January 1858 , Kansas voters defeated the proposed Lecompton Constitution , excerpted below , with an overwhelming margin of 10,226 to 138 .", "hl_sentences": "Proslavery Missourians who crossed the border to vote in Kansas became known as border ruffians ; these gained the advantage by winning the territorial elections , most likely through voter fraud and illegal vote counting .", "question": { "cloze_format": "Border ruffians helped to ________.", "normal_format": "What did border ruffians do to help?", "question_choices": [ "chase abolitionists out of Missouri", "elect a proslavery legislature in Kansas", "capture escaped enslaved people", "disseminate abolitionist literature in Kansas" ], "question_id": "fs-idp194400016", "question_text": "Border ruffians helped to ________." }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 2, "ans_text": "C" }, "bloom": null, "hl_context": "<hl> Defining American Roger Taney on Dred Scott v . Sandford In 1857 , the United States Supreme Court ended years of legal battles when it ruled that Dred Scott , an enslaved person who had resided in several free states , should remain enslaved . <hl> The decision , written by Chief Justice Roger Taney , also stated that Black people could not be citizens and that Congress had no power to limit the spread of slavery . The excerpt below is from Taney ’ s decision . In a complicated set of legal decisions , a jury found that Scott , along with his wife and two children , were free . <hl> However , on appeal from Scott ’ s owner , the state Superior Court reversed the decision , and the Scotts remained enslaved . <hl> Scott then became the property of John Sanford ( his name was misspelled as “ Sandford ” in later court documents ) , who lived in New York . He continued his legal battle , and because the issue involved Missouri and New York , the case fell under the jurisdiction of the federal court . In 1854 , Scott lost in federal court and appealed to the United States Supreme Court . In 1857 , several months after President Buchanan took the oath of office , the Supreme Court ruled in Dred Scott v . Sandford . Dred Scott ( Figure 14.16 ) , born with slave status in Virginia in 1795 , had been one of the thousands forced to relocate as a result of the massive internal slave trade and taken to Missouri , where slavery had been adopted as part of the Missouri Compromise . <hl> In 1820 , Scott ’ s owner took him first to Illinois and then to the Wisconsin territory . <hl> <hl> However , both of those regions were part of the Northwest Territory , where the 1787 Northwest Ordinance had prohibited slavery . <hl> <hl> When Scott returned to Missouri , he attempted to buy his freedom . <hl> <hl> After his owner refused , he sought relief in the state courts , arguing that by virtue of having lived in areas where slavery was banned , he should be free . <hl>", "hl_sentences": "Defining American Roger Taney on Dred Scott v . Sandford In 1857 , the United States Supreme Court ended years of legal battles when it ruled that Dred Scott , an enslaved person who had resided in several free states , should remain enslaved . However , on appeal from Scott ’ s owner , the state Superior Court reversed the decision , and the Scotts remained enslaved . In 1820 , Scott ’ s owner took him first to Illinois and then to the Wisconsin territory . However , both of those regions were part of the Northwest Territory , where the 1787 Northwest Ordinance had prohibited slavery . When Scott returned to Missouri , he attempted to buy his freedom . After his owner refused , he sought relief in the state courts , arguing that by virtue of having lived in areas where slavery was banned , he should be free .", "question": { "cloze_format": "Dred Scott sued for freedom on ground of ___.", "normal_format": "On what grounds did Dred Scott sue for freedom?", "question_choices": [ "the inherent inhumanity of slavery", "the cruelty of his enslaver", "the fact that he had lived in free states", "the fact that his family would be torn apart" ], "question_id": "fs-idp57101408", "question_text": "On what grounds did Dred Scott sue for freedom?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 3, "ans_text": "Lincoln successfully defended the principle of popular sovereignty." }, "bloom": null, "hl_context": "<hl> Though Douglas had survived the senate election challenge from Lincoln , his Freeport Doctrine damaged the political support he needed from the Southern Democrats . <hl> This helped him to lose the following presidential election , undermining the Democratic Party as a national force . 14.4 John Brown and the Election of 1860 Learning Objectives By the end of this section , you will be able to : During the debates , Lincoln demanded that Douglas explain whether or not he believed that the 1857 Supreme Court decision in the Dred Scott case trumped the right of a majority to prevent the expansion of slavery under the principle of popular sovereignty . Douglas responded to Lincoln during the second debate at Freeport , Illinois . In what became known as the Freeport Doctrine , Douglas adamantly upheld popular sovereignty , declaring : “ It matters not what way the Supreme Court may hereafter decide as to the abstract question whether slavery may or may not go into a territory under the Constitution , the people have the lawful means to introduce it or exclude it as they please . ” The Freeport Doctrine antagonized southerners who supported slavery , and caused a major rift in the Democratic Party . The doctrine did help Douglas in Illinois , however , where most voters opposed the further expansion of slavery . <hl> The Illinois legislature selected Douglas over Lincoln for the senate , but the debates had the effect of launching Lincoln into the national spotlight . <hl> Lincoln had argued that slavery was morally wrong , even as he accepted the racism inherent in slavery . <hl> He warned that Douglas and the Democrats would nationalize slavery through the policy of popular sovereignty . <hl> <hl> The turmoil in Kansas , combined with the furor over the Dred Scott decision , provided the background for the 1858 senatorial contest in Illinois between Democratic senator Stephen Douglas and Republican hopeful Abraham Lincoln ( Figure 14.17 ) . <hl> Lincoln and Douglas engaged in seven debates before huge crowds that met to hear the two men argue the central issue of slavery and its expansion . <hl> Newspapers throughout the United States published their speeches . <hl> Whereas Douglas already enjoyed national recognition , Lincoln remained largely unknown before the debates . These appearances provided an opportunity for him to raise his profile with both northerners and southerners .", "hl_sentences": "Though Douglas had survived the senate election challenge from Lincoln , his Freeport Doctrine damaged the political support he needed from the Southern Democrats . The Illinois legislature selected Douglas over Lincoln for the senate , but the debates had the effect of launching Lincoln into the national spotlight . He warned that Douglas and the Democrats would nationalize slavery through the policy of popular sovereignty . The turmoil in Kansas , combined with the furor over the Dred Scott decision , provided the background for the 1858 senatorial contest in Illinois between Democratic senator Stephen Douglas and Republican hopeful Abraham Lincoln ( Figure 14.17 ) . Newspapers throughout the United States published their speeches .", "question": { "cloze_format": "___ was not a result of the Lincoln-Douglas debate.", "normal_format": "Which of the following was not a result of the Lincoln-Douglas debates?", "question_choices": [ "Douglas was elected senator of Illinois.", "Lincoln’s national profile was raised.", "Citizens in both the North and South followed the debates closely.", "Lincoln successfully defended the principle of popular sovereignty." ], "question_id": "fs-idm88734272", "question_text": "Which of the following was not a result of the Lincoln-Douglas debates?" }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 0, "ans_text": "to seize weapons to distribute to enslaved people for a massive uprising" }, "bloom": null, "hl_context": "<hl> Brown had gone to Kansas in the 1850s in an effort to stop slavery , and there , he had perpetrated the killings at Pottawatomie . <hl> <hl> He told other abolitionists of his plan to take Harpers Ferry Armory and initiate a massive slave uprising . <hl> Some abolitionists provided financial support , while others , including Frederick Douglass , found the plot suicidal and refused to join . On October 16 , 1859 , Brown ’ s force easily took control of the federal armory , which was unguarded ( Figure 14.19 ) . However , his vision of a mass uprising failed completely . Very few enslaved people lived in the area to rally to Brown ’ s side , and the group found themselves holed up in the armory ’ s engine house with townspeople taking shots at them . Federal troops , commanded by Colonel Robert E . Lee , soon captured Brown and his followers . On December 2 , Brown was hanged by the state of Virginia for treason . <hl> In October 1859 , the radical abolitionist John Brown and eighteen armed men , both Black and White , attacked the federal arsenal in Harpers Ferry , Virginia . <hl> <hl> They hoped to capture the weapons there and distribute them among enslaved people to begin a massive uprising that would bring an end to slavery . <hl> Brown had already demonstrated during the 1856 Pottawatomie attack in Kansas that he had no patience for the nonviolent approach preached by pacifist abolitionists like William Lloyd Garrison . Born in Connecticut in 1800 , Brown ( Figure 14.18 ) spent much of his life in the North , moving from Ohio to Pennsylvania and then upstate New York as his various business ventures failed . To him , slavery appeared an unacceptable evil that must be purged from the land , and like his Puritan forebears , he believed in using the sword to defeat the ungodly .", "hl_sentences": "Brown had gone to Kansas in the 1850s in an effort to stop slavery , and there , he had perpetrated the killings at Pottawatomie . He told other abolitionists of his plan to take Harpers Ferry Armory and initiate a massive slave uprising . In October 1859 , the radical abolitionist John Brown and eighteen armed men , both Black and White , attacked the federal arsenal in Harpers Ferry , Virginia . They hoped to capture the weapons there and distribute them among enslaved people to begin a massive uprising that would bring an end to slavery .", "question": { "cloze_format": "John Brown attacked the armory at Harpers Ferry ___.", "normal_format": "Why did John Brown attack the armory at Harpers Ferry?", "question_choices": [ "to seize weapons to distribute to enslaved people for a massive uprising", "to hold as a military base against proslavery forces", "in revenge after the sacking of Lawrence", "to prevent southern states from seceding" ], "question_id": "fs-idm13059088", "question_text": "Why did John Brown attack the armory at Harpers Ferry?" }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 1, "ans_text": "B" }, "bloom": null, "hl_context": "<hl> By offering two candidates for president , the Democrats gave the Republicans an enormous advantage . <hl> <hl> Also hoping to prevent a Republican victory , pro-Unionists from the border states organized the Constitutional Union Party and put up a fourth candidate , John Bell , for president , who pledged to end slavery agitation and preserve the Union but never fully explained how he ’ d accomplish this objective . <hl> In a pro-Lincoln political cartoon of the time ( Figure 14.20 ) , the presidential election is presented as a baseball game . Lincoln stands on home plate . A skunk raises its tail at the other candidates . Holding his nose , southern Democrat John Breckinridge holds a bat labeled “ Slavery Extension ” and declares “ I guess I ’ d better leave for Kentucky , for I smell something strong around here , and begin to think , that we are completely skunk ’ d . ” The Democratic nominating convention met in April 1860 in Charleston , South Carolina . However , it broke up after northern Democrats , who made up a majority of delegates , rejected Jefferson Davis ’ s efforts to protect slavery in the territories . These northern Democratic delegates knew that supporting Davis on this issue would be very unpopular among the people in their states . A second conference , held in Baltimore , further illustrated the divide within the Democratic Party . <hl> Northern Democrats nominated Stephen Douglas , while southern Democrats , who met separately , put forward Vice President John Breckinridge from Kentucky . <hl> <hl> The Democratic Party had fractured into two competing sectional factions . <hl> The election of 1860 threatened American democracy when the elevation of Abraham Lincoln to the presidency inspired secessionists in the South to withdraw their states from the Union . <hl> Lincoln ’ s election owed much to the disarray in the Democratic Party . <hl> <hl> The Dred Scott decision and the Freeport Doctrine had opened up huge sectional divisions among Democrats . <hl> Though Brown did not intend it , his raid had furthered the split between northern and southern Democrats . <hl> Fire-Eaters vowed to prevent a northern Democrat , especially Illinois ’ s Stephen Douglas , from becoming their presidential candidate . <hl> <hl> These proslavery zealots insisted on a southern Democrat . <hl>", "hl_sentences": "By offering two candidates for president , the Democrats gave the Republicans an enormous advantage . Also hoping to prevent a Republican victory , pro-Unionists from the border states organized the Constitutional Union Party and put up a fourth candidate , John Bell , for president , who pledged to end slavery agitation and preserve the Union but never fully explained how he ’ d accomplish this objective . Northern Democrats nominated Stephen Douglas , while southern Democrats , who met separately , put forward Vice President John Breckinridge from Kentucky . The Democratic Party had fractured into two competing sectional factions . Lincoln ’ s election owed much to the disarray in the Democratic Party . The Dred Scott decision and the Freeport Doctrine had opened up huge sectional divisions among Democrats . Fire-Eaters vowed to prevent a northern Democrat , especially Illinois ’ s Stephen Douglas , from becoming their presidential candidate . These proslavery zealots insisted on a southern Democrat .", "question": { "cloze_format": "___ did not contribute to Lincoln’s victory in the election of 1860.", "normal_format": "Which of the following did not contribute to Lincoln’s victory in the election of 1860?", "question_choices": [ "the split between northern and southern democrats", "the defeat of the Whig party", "Lincoln’s improved national standing after his senatorial debates with Stephen Douglas", "the Constitutional Union party’s further splintering the vote" ], "question_id": "fs-idm77648032", "question_text": "Which of the following did not contribute to Lincoln’s victory in the election of 1860?" }, "references_are_paraphrase": 0 } ]
14
14.1 The Compromise of 1850 Learning Objectives By the end of this section, you will be able to: Explain the contested issues that led to the Compromise of 1850 Describe and analyze the reactions to the 1850 Fugitive Slave Act At the end of the Mexican-American War, the United States gained a large expanse of western territory known as the Mexican Cession. The disposition of this new territory was in question; would the new states be slave states or free-soil states? In the long run, the Mexican-American War achieved what abolitionism alone had failed to do: it mobilized many in the North against slavery. Antislavery northerners clung to the idea expressed in the 1846 Wilmot Proviso: slavery would not expand into the areas taken, and later bought, from Mexico. Though the proviso remained a proposal and never became a law, it defined the sectional division. The Free-Soil Party, which formed at the conclusion of the Mexican-American War in 1848 and included many members of the failed Liberty Party, made this position the centerpiece of all its political activities, ensuring that the issue of slavery and its expansion remained at the front and center of American political debate. Supporters of the Wilmot Proviso and members of the new Free-Soil Party did not want to abolish slavery in the states where it already existed; rather, Free-Soil advocates demanded that the western territories be kept free of slavery for the benefit of White laborers who might settle there. They wanted to protect White workers from having to compete with slave labor in the West. (Abolitionists, in contrast, looked to destroy slavery everywhere in the United States.) Southern extremists, especially wealthy slaveholders, reacted with outrage at this effort to limit slavery’s expansion. They argued for the right to bring their enslaved property west, and they vowed to leave the Union if necessary to protect their way of life—meaning the right to enslave people—and ensure that the American empire of slavery would continue to grow. BROKERING THE COMPROMISE The issue of what to do with the western territories added to the republic by the Mexican Cession consumed Congress in 1850. Other controversial matters, which had been simmering over time, complicated the problem further. Chief among these issues were the slave trade in the District of Columbia, which antislavery advocates hoped to end, and the fugitive slave laws, which southerners wanted to strengthen. The border between Texas and New Mexico remained contested because many Texans hoped to enlarge their state further, and, finally, the issue of California had not been resolved. California was the crown jewel of the Mexican Cession, and following the discovery of gold, it was flush with thousands of emigrants. By most estimates, however, it would be a free state, since the former Mexican ban on slavery still remained in force and slavery had not taken root in California. The map below ( Figure 14.3 ) shows the disposition of land before the 1850 compromise. The presidential election of 1848 did little to solve the problems resulting from the Mexican Cession. Both the Whigs and the Democrats attempted to avoid addressing the issue of slavery publicly as much as possible. The Democrats nominated Lewis Cass of Michigan, a supporter of the idea of popular sovereignty, or letting the people in the territories decide the issue of whether or not to permit slavery based on majority rule. The Whigs nominated General Zachary Taylor, a slaveholder from Louisiana, who had achieved national prominence as a military hero in the Mexican-American War. Taylor did not take a personal stand on any issue and remained silent throughout the campaign. The fledgling Free-Soil Party put forward former president Martin Van Buren as their candidate. The Free-Soil Party attracted northern Democrats who supported the Wilmot Proviso, northern Whigs who rejected Taylor because he was a slaveholder, former members of the Liberty Party, and other abolitionists. Both the Whigs and the Democrats ran different campaigns in the North and South. In the North, all three parties attempted to win voters with promises of keeping the territories free of slavery, while in the South, Whigs and Democrats promised to protect slavery in the territories. For southern voters, the slaveholder Taylor appeared the natural choice. In the North, the Free-Soil Party took votes away from Whigs and Democrats and helped to ensure Taylor’s election in 1848. As president, Taylor sought to defuse the sectional controversy as much as possible, and, above all else, to preserve the Union. Although Taylor was born in Virginia before relocating to Kentucky and enslaved more than one hundred people by the late 1840s, he did not push for slavery’s expansion into the Mexican Cession. However, the California Gold Rush made California’s statehood into an issue demanding immediate attention. In 1849, after California residents adopted a state constitution prohibiting slavery, President Taylor called on Congress to admit California and New Mexico as free states, a move that infuriated southern defenders of slavery who argued for the right to bring their enslaved property wherever they chose. Taylor, who did not believe slavery could flourish in the arid lands of the Mexican Cession because the climate prohibited plantation-style farming, proposed that the Wilmot Proviso be applied to the entire area. In Congress, Kentucky senator Henry Clay, a veteran of congressional conflicts, offered a series of resolutions addressing the list of issues related to slavery and its expansion. Clay’s resolutions called for the admission of California as a free state; no restrictions on slavery in the rest of the Mexican Cession (a rejection of the Wilmot Proviso and the Free-Soil Party’s position); a boundary between New Mexico and Texas that did not expand Texas (an important matter, since Texas allowed slavery and a larger Texas meant more opportunities for the expansion of slavery); payment of outstanding Texas debts from the Lone Star Republic days; and the end of the slave trade (but not of slavery) in the nation’s capital, coupled with a more robust federal fugitive slave law. Clay presented these proposals as an omnibus bill, that is, one that would be voted on its totality. Clay’s proposals ignited a spirited and angry debate that lasted for eight months. The resolution calling for California to be admitted as a free state aroused the wrath of the aged and deathly ill John C. Calhoun, the elder statesman for the proslavery position. Calhoun, too sick to deliver a speech, had his friend Virginia senator James Mason present his assessment of Clay’s resolutions and the current state of sectional strife. In Calhoun’s eyes, blame for the stalemate fell squarely on the North, which stood in the way of southern and American prosperity by limiting the zones where slavery could flourish. Calhoun called for a vigorous federal law to ensure that enscaped enslaved people were returned to their enslavers. He also proposed a constitutional amendment specifying a dual presidency—one office that would represent the South and another for the North—a suggestion that hinted at the possibility of disunion. Calhoun’s argument portrayed an embattled South faced with continued northern aggression—a line of reasoning that only furthered the sectional divide. Several days after Mason delivered Calhoun’s speech, Massachusetts senator Daniel Webster countered Calhoun in his “Seventh of March” speech. Webster called for national unity, famously declaring that he spoke “not as a Massachusetts man, not as a Northern man, but as an American.” Webster asked southerners to end threats of disunion and requested that the North stop antagonizing the South by harping on the Wilmot Proviso. Like Calhoun, Webster also called for a new federal law to ensure the return of escaped enslaved people. Webster’s efforts to compromise led many abolitionist sympathizers to roundly denounce him as a traitor. Whig senator William H. Seward, who aspired to be president, declared that slavery—which he characterized as incompatible with the assertion in the Declaration of Independence that “all men are created equal”—would one day be extinguished in the United States. Seward’s speech, in which he invoked the idea of a higher moral law than the Constitution, secured his reputation in the Senate as an advocate of abolition. The speeches made in Congress were published in the nation’s newspapers, and the American public followed the debates with great interest, anxious to learn how the issues of the day, especially the potential advance of slavery, would be resolved. Colorful reports of wrangling in Congress further piqued public interest. Indeed, it was not uncommon for arguments to devolve into fistfights or worse. One of the most astonishing episodes of the debate occurred in April 1850, when a quarrel erupted between Missouri Democratic senator Thomas Hart Benton, who by the time of the debate had become a critic of slavery (despite being an enslaver), and Mississippi Democratic senator Henry S. Foote. When the burly Benton appeared ready to assault Foote, the Mississippi senator drew his pistol ( Figure 14.4 ). President Taylor and Henry Clay, whose resolutions had begun the verbal fireworks in the Senate, had no patience for each other. Clay had long harbored ambitions for the White House, and, for his part, Taylor resented Clay and disapproved of his resolutions. With neither side willing to budge, the government stalled on how to resolve the disposition of the Mexican Cession and the other issues of slavery. The drama only increased when on July 4, 1850, President Taylor became gravely ill, reportedly after eating an excessive amount of fruit washed down with milk. He died five days later, and Vice President Millard Fillmore became president. Unlike his predecessor, who many believed would be opposed to a compromise, Fillmore worked with Congress to achieve a solution to the crisis of 1850. In the end, Clay stepped down as leader of the compromise effort in frustration, and Illinois senator Stephen Douglas pushed five separate bills through Congress, collectively composing the Compromise of 1850. First, as advocated by the South, Congress passed the Fugitive Slave Act, a law that provided federal money—or “bounties”—to slave-catchers. Second, to balance this concession to the South, Congress admitted California as a free state, a move that cheered antislavery advocates and abolitionists in the North. Third, Congress settled the contested boundary between New Mexico and Texas by favoring New Mexico and not allowing for an enlarged Texas, another outcome pleasing to the North. In return, the federal government paid the debts Texas had incurred as an independent republic. Fourth, antislavery advocates welcomed Congress’s ban on the slave trade in Washington, DC, although slavery continued to thrive in the nation’s capital. Finally, on the thorny issue of whether slavery would expand into the territories, Congress avoided making a direct decision and instead relied on the principle of popular sovereignty. This put the onus on residents of the territories to decide for themselves whether to allow slavery. Popular sovereignty followed the logic of American democracy; majorities in each territory would decide the territory’s laws. The compromise, however, further exposed the sectional divide as votes on the bills divided along strict regional lines. Most Americans breathed a sigh of relief over the deal brokered in 1850, choosing to believe it had saved the Union. Rather than resolving divisions between the North and the South, however, the compromise stood as a truce in an otherwise white-hot sectional conflict. Tensions in the nation remained extremely high; indeed, southerners held several conventions after the compromise to discuss ways to protect the South. At these meetings, extremists who called for secession found themselves in the minority, since most southerners committed themselves to staying in the Union—but only if slavery remained in the states where it already existed, and if no effort was made to block its expansion into areas where citizens wanted it, thereby applying the idea of popular sovereignty ( Figure 14.5 ). THE FUGITIVE SLAVE ACT AND ITS CONSEQUENCES The hope that the Compromise of 1850 would resolve the sectional crisis proved short-lived when the Fugitive Slave Act turned into a major source of conflict. The federal law imposed heavy fines and prison sentences on northerners and midwesterners who aided those who had escaped their captivity or refused to join posses to catch freedom-seekers. Many northerners felt the law forced them to act as slave-catchers against their will. The law also established a new group of federal commissioners who would decide the fate of freedom-seekers brought before them. In some instances, slave-catchers even brought in free northern Black people, prompting abolitionist societies to step up their efforts to prevent kidnappings ( Figure 14.6 ). The commissioners had a financial incentive to send recaptured enslaved and free Black people to the slaveholding South, since they received ten dollars for every African American sent to the South and only five if they decided the person who came before them was actually free. The commissioners used no juries, and the alleged runaways could not testify in their own defense. The operation of the law further alarmed northerners and confirmed for many the existence of a “ Slave Power ”—that is, a minority of elite slaveholders who wielded a disproportionate amount of power over the federal government, shaping domestic and foreign policies to suit their interests. Despite southerners’ repeated insistence on states’ rights, the Fugitive Slave Act showed that slaveholders were willing to use the power of the federal government to bend people in other states to their will. While rejecting the use of federal power to restrict the expansion of slavery, proslavery southerners turned to the federal government to protect and promote the institution of slavery. The actual number of freedom-seekers who were not captured within a year of escaping remained very low, perhaps no more than one thousand per year in the early 1850s. Most stayed in the South, hiding in plain sight among free Black people in urban areas. Nonetheless, southerners feared the influence of a vast Underground Railroad : the network of northern White and free Black people who sympathized with escapees and provided safe houses and safe passage from the South. Quakers, who had long been troubled by slavery, were especially active in this network. It is unclear how many enslaved people escaped through the Underground Railroad, but historians believe that between 50,000 and 100,000 used the network in their bids for freedom. Meanwhile, the 1850 Fugitive Slave Act greatly increased the perils of being captured. For many thousands of freedom-seekers, escaping the United States completely by going to southern Ontario, Canada, where slavery had been abolished, offered the best chance of a better life beyond the reach of slaveholders. Harriet Tubman, one of the thousands of enslaved people who made their escape through the Underground Railroad, distinguished herself for her efforts in helping other enslaved men and women escape. Born a slave in Maryland around 1822, Tubman, who suffered greatly under slavery but found solace in Christianity, made her escape in the late 1840s. She returned to the South more than a dozen times to lead other enslaved people, including her family and friends, along the Underground Railroad to freedom. Defining American Harriet Tubman: An American Moses? Harriet Tubman ( Figure 14.7 ) was a legendary figure in her own time and beyond. An escaped enslaved person herself, she returned to the South thirteen times to help over three hundred other freedom-seekers through the Underground Railroad to liberty in the North. In 1869, printer William J. Moses published Sarah H. Bradford’s Scenes in the Life of Harriet Tubman . Bradford was a writer and biographer who had known Tubman’s family for years. The excerpt below is from the beginning of her book, which she updated in 1886 under the title Harriet, the Moses of Her People . It is proposed in this little book to give a plain and unvarnished account of some scenes and adventures in the life of a woman who, though one of earth’s lowly ones, and of dark-hued skin, has shown an amount of heroism in her character rarely possessed by those of any station in life. Her name (we say it advisedly and without exaggeration) deserves to be handed down to posterity side by side with the names of Joan of Arc, Grace Darling, and Florence Nightingale; for not one of these women has shown more courage and power of endurance in facing danger and death to relieve human suffering, than has this woman in her heroic and successful endeavors to reach and save all whom she might of her oppressed and suffering race, and to pilot them from the land of Bondage to the promised land of Liberty. Well has she been called “Moses,” for she has been a leader and deliverer unto hundreds of her people. —Sarah H. Bradford, Scenes in the Life of Harriet Tubman How does Bradford characterize Tubman? What language does Bradford use to tie religion into the fight for freedom? The Fugitive Slave Act provoked widespread reactions in the North. Some abolitionists, such as Frederick Douglass, believed that standing up against the law necessitated violence. In Boston and elsewhere, abolitionists tried to protect fugitives from federal authorities. One case involved Anthony Burns, who had escaped slavery in Virginia in 1853 and made his way to Boston ( Figure 14.8 ). When federal officials arrested Burns in 1854, abolitionists staged a series of mass demonstrations and a confrontation at the courthouse. Despite their best efforts, however, Burns was returned to Virginia when President Franklin Pierce supported the Fugitive Slave Act with federal troops. Boston abolitionists eventually bought Burns’s freedom. For many northerners, however, the Burns incident, combined with Pierce’s response, only amplified their sense of a conspiracy of southern power. The most consequential reaction against the Fugitive Slave Act came in the form of a novel, Uncle Tom’s Cabin . In it, author Harriet Beecher Stowe, born in Connecticut, made use of enslaved people’s stories she had heard firsthand after marrying and moving to Ohio, then on the country’s western frontier. Her novel first appeared as a series of stories in a Free-Soil newspaper, the National Era , in 1851 and was published as a book the following year. Stowe told the tale of enslaved people who were sold by their Kentucky enslaver. While Uncle Tom is indeed sold down the river, young Eliza escapes with her baby ( Figure 14.9 ). The story highlighted the idea that slavery was a sin because it destroyed families, ripping children from their parents and husbands and wives from one another. Stowe also emphasized the ways in which slavery corrupted White citizens. The cruelty of some of the novel’s White slaveholders (who genuinely believe that enslaved people don’t feel things the way that White people do) and the brutality of the slave dealer Simon Legree, who beats enslaved people and sexually exploits an enslaved woman, demonstrate the dehumanizing effect of the institution even on those who benefit from it. Stowe’s novel proved a runaway bestseller and was the most-read novel of the nineteenth century, inspiring multiple theatrical productions and musical compositions. It was translated into sixty languages and remains in print to this day. Its message about the evils of slavery helped convince many northerners of the righteousness of the cause of abolition. The novel also demonstrated the power of women to shape public opinion. Stowe and other American women believed they had a moral obligation to mold the conscience of the United States, even though they could not vote ( Figure 14.10 ). The backlash against the Fugitive Slave Act, fueled by Uncle Tom’s Cabin and well-publicized cases like that of Anthony Burns, also found expression in personal liberty laws passed by eight northern state legislatures. These laws emphasized that the state would provide legal protection to anyone arrested as an escaped slave, including the right to trial by jury. The personal liberty laws stood as a clear-cut example of the North’s use of states’ rights in opposition to federal power while providing further evidence to southerners that northerners had no respect for the Fugitive Slave Act or slaveholders’ property rights. 14.2 The Kansas-Nebraska Act and the Republican Party Learning Objectives By the end of this section, you will be able to: Explain the political ramifications of the Kansas-Nebraska Act Describe the founding of the Republican Party In the early 1850s, the United States’ sectional crisis had abated somewhat, cooled by the Compromise of 1850 and the nation’s general prosperity. In 1852, voters went to the polls in a presidential contest between Whig candidate Winfield Scott and Democratic candidate Franklin Pierce. Both men endorsed the Compromise of 1850. Though it was considered unseemly to hit the campaign trail, Scott did so—much to the benefit of Pierce, as Scott’s speeches focused on forty-year-old battles during the War of 1812 and the weather. In New York, Scott, known as “Old Fuss and Feathers,” talked about a thunderstorm that did not occur and greatly confused the crowd. In Ohio, a cannon firing to herald Scott’s arrival killed a spectator. Pierce was a supporter of the “Young America” movement of the Democratic Party, which enthusiastically anticipated extending democracy around the world and annexing additional territory for the United States. Pierce did not take a stance on the slavery issue. Helped by Scott’s blunders and the fact that he had played no role in the bruising political battles of the past five years, Pierce won the election. The brief period of tranquility between the North and South did not last long, however; it came to an end in 1854 with the passage of the Kansas-Nebraska Act. This act led to the formation of a new political party, the Republican Party, that committed itself to ending the further expansion of slavery. THE KANSAS-NEBRASKA ACT The relative calm over the sectional issue was broken in 1854 over the issue of slavery in the territory of Kansas. Pressure had been building among northerners to organize the territory west of Missouri and Iowa, which had been admitted to the Union as a free state in 1846. This pressure came primarily from northern farmers, who wanted the federal government to survey the land and put it up for sale. Promoters of a transcontinental railroad were also pushing for this westward expansion. Southerners, however, had long opposed the Wilmot Proviso’s stipulation that slavery should not expand into the West. By the 1850s, many in the South were also growing resentful of the Missouri Compromise of 1820, which established the 36° 30' parallel as the geographical boundary of slavery on the north-south axis. Proslavery southerners now contended that popular sovereignty should apply to all territories, not just Utah and New Mexico. They argued for the right to bring their enslaved property wherever they chose. Attitudes toward slavery in the 1850s were represented by a variety of regional factions. For three decades, the abolitionists remained a minority, but they had a significant effect on American society by bringing the evils of slavery into the public consciousness. In 1840, the Liberty Party was the first political organization to campaign for abolition. This group sought to work within the existing political system, a strategy Garrison and others rejected. Meanwhile, the Free-Soil Party committed itself to ensuring that White laborers would find work in newly acquired territories and not have to compete with unpaid enslaved people. By the 1850s, some abolitionists advocated the use of violence against slaveholders. It is important to note that, even among those who opposed the expansion of slavery in the West, very different attitudes toward slavery existed. Some antislavery northerners wanted the West to be the best country for poor Whites to go and seek opportunity. They did not want White workers to have to compete with slave labor, a contest that they believed demeaned White labor. Radical abolitionists, in contrast, envisioned the end of all slavery, and a society of equality between Blacks and Whites. Others opposed slavery in principle, but believed that the best approach was colonization; that is, settling freed enslaved people in a colony in Africa. The growing political movement to address the issue of slavery stiffened the resolve of southern slaveholders to defend themselves and their society at all costs. Prohibiting slavery’s expansion, they argued, ran counter to basic American property rights. As abolitionists fanned the flames of antislavery sentiment, southerners solidified their defense of their enormous investment in human chattel. Across the country, people of all political stripes worried that the nation’s arguments would cause irreparable rifts in the country ( Figure 14.11 ). As these different factions were agitating for the settlement of Kansas and Nebraska, leaders of the Democratic Party in 1853 and 1854 sought to bind their party together in the aftermath of intraparty fights over the distribution of patronage jobs. Illinois Democratic senator Stephen Douglas believed he had found a solution—the Kansas-Nebraska bill —that would promote party unity and also satisfy his colleagues from the South, who detested the Missouri Compromise line. In January 1854, Douglas introduced the bill ( Figure 14.12 ). The act created two territories: Kansas, directly west of Missouri; and Nebraska, west of Iowa. The act also applied the principle of popular sovereignty, dictating that the people of these territories would decide for themselves whether to adopt slavery. In a concession crucial to many southerners, the proposed bill would also repeal the 36° 30' line from the Missouri Compromise. Douglas hoped his bill would increase his political capital and provide a step forward on his quest for the presidency. Douglas also wanted the territory organized in hopes of placing the eastern terminus of a transcontinental railroad in Chicago, rather than St. Louis or New Orleans. After heated debates, Congress narrowly passed the Kansas-Nebraska Act. (In the House of Representatives, the bill passed by a mere three votes: 113 to 110.) This move had major political consequences. The Democrats divided along sectional lines as a result of the bill, and the Whig party, in decline in the early 1850s, found its political power slipping further. Most important, the Kansas-Nebraska Act gave rise to the Republican Party , a new political party that attracted northern Whigs, Democrats who shunned the Kansas-Nebraska Act, members of the Free-Soil Party, and assorted abolitionists. Indeed, with the formation of the Republican Party, the Free-Soil Party ceased to exist. The new Republican Party pledged itself to preventing the spread of slavery into the territories and railed against the Slave Power, infuriating the South. As a result, the party became a solidly northern political organization. As never before, the U.S. political system was polarized along sectional fault lines. BLEEDING KANSAS In 1855 and 1856, pro- and antislavery activists flooded Kansas with the intention of influencing the popular-sovereignty rule of the territories. Proslavery Missourians who crossed the border to vote in Kansas became known as border ruffians ; these gained the advantage by winning the territorial elections, most likely through voter fraud and illegal vote counting. (By some estimates, up to 60 percent of the votes cast in Kansas were fraudulent.) Once in power, the proslavery legislature, meeting at Lecompton, Kansas, drafted a proslavery constitution known as the Lecompton Constitution. It was supported by President Buchanan, but opposed by Democratic Senator Stephen A. Douglas of Illinois. Defining American The Lecompton Constitution Kansas was home to no fewer than four state constitutions in its early years. Its first constitution, the Topeka Constitution, would have made Kansas a free-soil state. A proslavery legislature, however, created the 1857 Lecompton Constitution to enshrine the institution of slavery in the new Kansas-Nebraska territories. In January 1858, Kansas voters defeated the proposed Lecompton Constitution, excerpted below, with an overwhelming margin of 10,226 to 138. ARTICLE VII.—SLAVERY SECTION 1. The right of property is before and higher than any constitutional sanction, and the right of the owner of a slave to such slave and its increase is the same and as inviolable as the right of the owner of any property whatever. SEC. 2. The Legislature shall have no power to pass laws for the emancipation of slaves without the consent of the owners, or without paying the owners previous to their emancipation a full equivalent in money for the slaves so emancipated. They shall have no power to prevent immigrants to the State from bringing with them such persons as are deemed slaves by the laws of any one of the United States or Territories, so long as any person of the same age or description shall be continued in slavery by the laws of this State: Provided, That such person or slave be the bona fide property of such immigrants. How are slaves defined in the 1857 Kansas constitution? How does this constitution safeguard the rights of slaveholders? The majority in Kansas, however, were Free-Soilers who seethed at the border ruffians’ co-opting of the democratic process ( Figure 14.13 ). Many had come from New England to ensure a numerical advantage over the border ruffians. The New England Emigrant Aid Society, a northern antislavery group, helped fund these efforts to halt the expansion of slavery into Kansas and beyond. In 1856, clashes between antislavery Free-Soilers and border ruffians came to a head in Lawrence, Kansas. The town had been founded by the New England Emigrant Aid Society, which funded antislavery settlement in the territory and were determined that Kansas should be a free-soil state. Proslavery emigrants from Missouri were equally determined that no “abolitionist tyrants” or “negro thieves” would control the territory. In the spring of 1856, several of Lawrence’s leading antislavery citizens were indicted for treason, and federal marshal Israel Donaldson called for a posse to help make arrests. He did not have trouble finding volunteers from Missouri. When the posse, which included Douglas County sheriff Samuel Jones, arrived outside Lawrence, the antislavery town’s “committee of safety” agreed on a policy of nonresistance. Most of those who were indicted fled. Donaldson arrested two men without incident and dismissed the posse. However, Jones, who had been shot during an earlier confrontation in the town, did not leave. On May 21, falsely claiming that he had a court order to do so, Jones took command of the posse and rode into town armed with rifles, revolvers, cutlasses and bowie knives. At the head of the procession, two flags flew: an American flag and a flag with a crouching tiger. Other banners followed, bearing the words “Southern rights” and “The Superiority of the White Race.” In the rear were five artillery pieces, which were dragged to the center of town. The posse smashed the presses of the two newspapers, Herald of Freedom and the Kansas Free State , and burned down the deserted Free State Hotel ( Figure 14.14 ). When the posse finally left, Lawrence residents found themselves unharmed but terrified. The next morning, a man named John Brown and his sons, who were on their way to provide Lawrence with reinforcements, heard the news of the attack. Brown, a strict, God-fearing Calvinist and staunch abolitionist, once remarked that “God had raised him up on purpose to break the jaws of the wicked.” Disappointed that the citizens of Lawrence did not resist the “slave hounds” of Missouri, Brown opted not to go to Lawrence, but to the homes of proslavery settlers near Pottawatomie Creek in Kansas. The group of seven, including Brown’s four sons, arrived on May 24, 1856, and announced they were the “Northern Army” that had come to serve justice. They burst into the cabin of proslavery Tennessean James Doyle and marched him and two of his sons off, sparing the youngest at the desperate request of Doyle’s wife, Mahala. One hundred yards down the road, Owen and Salmon Brown hacked their captives to death with broadswords and John Brown shot a bullet into Doyle’s forehead. Before the night was done, the Browns visited two more cabins and brutally executed two other proslavery settlers. None of those executed enslaved any people or had had anything to do with the raid on Lawrence. Brown’s actions precipitated a new wave of violence. All told, the guerilla warfare between proslavery “border ruffians” and antislavery forces, which would continue and even escalate during the Civil War, resulted in over 150 deaths and significant property loss. The events in Kansas served as an extreme reply to Douglas’s proposition of popular sovereignty. As the violent clashes increased, Kansas became known as “ Bleeding Kansas .” Antislavery advocates’ use of force carved out a new direction for some who opposed slavery. Distancing themselves from William Lloyd Garrison and other pacifists, Brown and fellow abolitionists believed the time had come to fight slavery with violence. The violent hostilities associated with Bleeding Kansas were not limited to Kansas itself. It was the controversy over Kansas that prompted the caning of Charles Sumner, introduced at the beginning of this chapter with the political cartoon Southern Chivalry: Argument versus Club’s ( Figure 14.1 ). Note the title of the cartoon; it lampoons the southern ideal of chivalry, the code of behavior that Preston Brooks believed he was following in his attack on Sumner. In Sumner’s “Crime against Kansas” speech he went much further than politics, filling his verbal attack with allusions to sexuality by singling out fellow senator Andrew Butler from South Carolina, a zealous supporter of slavery and Brooks’s uncle. Sumner insulted Butler by comparing slavery to prostitution, declaring, “Of course he [Butler] has chosen a mistress to whom he has made his vows, and who, though ugly to others, is always lovely to him; though polluted in the sight of the world, is chaste in his sight. I mean the harlot Slavery.” Because Butler was aged, it was his nephew, Brooks, who sought satisfaction for Sumner’s attack on his family and southern honor. Brooks did not challenge Sumner to a duel; by choosing to beat him with a cane instead, he made it clear that he did not consider Sumner a gentleman. Many in the South rejoiced over Brooks’s defense of slavery, southern society, and family honor, sending him hundreds of canes to replace the one he had broken assaulting Sumner. The attack by Brooks left Sumner incapacitated physically and mentally for a long period of time. Despite his injuries, the people of Massachusetts reelected him. THE PRESIDENTIAL ELECTION OF 1856 The electoral contest in 1856 took place in a transformed political landscape. A third political party appeared: the anti-immigrant American Party , a formerly secretive organization with the nickname “the Know-Nothing Party” because its members denied knowing anything about it. By 1856, the American or Know-Nothing Party had evolved into a national force committed to halting further immigration. Its members were especially opposed to the immigration of Irish Catholics, whose loyalty to the Pope, they believed, precluded their loyalty to the United States. On the West Coast, they opposed the entry of immigrant laborers from China, who were thought to be too foreign to ever assimilate into a White America. The election also featured the new Republican Party, which offered John C. Fremont as its candidate. Republicans accused the Democrats of trying to nationalize slavery through the use of popular sovereignty in the West, a view captured in the 1856 political cartoon Forcing Slavery Down the Throat of a Free Soiler ( Figure 14.15 ). The cartoon features the image of a Free-Soiler settler tied to the Democratic Party platform while Senator Douglas (author of the Kansas-Nebraska Act) and President Pierce force an enslaved person down his throat. Note that the slave cries out “Murder!!! Help—neighbors help, O my poor Wife and Children,” a reference to the abolitionists’ argument that slavery destroyed families. The Democrats offered James Buchanan as their candidate. Buchanan did not take a stand on either side of the issue of slavery; rather, he attempted to please both sides. His qualification, in the minds of many, was that he was out of the country when the Kansas-Nebraska Act was passed. In the above political cartoon, Buchanan, along with Democratic senator Lewis Cass, holds down the Free-Soil advocate. Buchanan won the election, but Fremont garnered more than 33 percent of the popular vote, an impressive return for a new party. The Whigs had ceased to exist and had been replaced by the Republican Party. Know-Nothings also transferred their allegiance to the Republicans because the new party also took an anti-immigrant stance, a move that further boosted the new party’s standing. (The Democrats courted the Catholic immigrant vote.) The Republican Party was a thoroughly northern party; no southern delegate voted for Fremont. 14.3 The Dred Scott Decision and Sectional Strife Learning Objectives By the end of this section, you will be able to: Explain the importance of the Supreme Court's Dred Scott ruling Discuss the principles of the Republican Party as expressed by Abraham Lincoln in 1858 As president, Buchanan confronted a difficult and volatile situation. The nation needed a strong personality to lead it, and Buchanan did not possess this trait. The violence in Kansas demonstrated that applying popular sovereignty—the democratic principle of majority rule—to the territory offered no solution to the national battle over slavery. A decision by the Supreme Court in 1857, which concerned the enslaved Dred Scott, only deepened the crisis. DRED SCOTT In 1857, several months after President Buchanan took the oath of office, the Supreme Court ruled in Dred Scott v. Sandford . Dred Scott ( Figure 14.16 ), born with slave status in Virginia in 1795, had been one of the thousands forced to relocate as a result of the massive internal slave trade and taken to Missouri, where slavery had been adopted as part of the Missouri Compromise. In 1820, Scott’s owner took him first to Illinois and then to the Wisconsin territory. However, both of those regions were part of the Northwest Territory, where the 1787 Northwest Ordinance had prohibited slavery. When Scott returned to Missouri, he attempted to buy his freedom. After his owner refused, he sought relief in the state courts, arguing that by virtue of having lived in areas where slavery was banned, he should be free. In a complicated set of legal decisions, a jury found that Scott, along with his wife and two children, were free. However, on appeal from Scott’s owner, the state Superior Court reversed the decision, and the Scotts remained enslaved. Scott then became the property of John Sanford (his name was misspelled as “Sandford” in later court documents), who lived in New York. He continued his legal battle, and because the issue involved Missouri and New York, the case fell under the jurisdiction of the federal court. In 1854, Scott lost in federal court and appealed to the United States Supreme Court. In 1857, the Supreme Court—led by Chief Justice Roger Taney, a former slaveholder who had freed his those he had enslaved—handed down its decision. On the question of whether Scott was free, the Supreme Court decided he remained enslaved. The court then went beyond the specific issue of Scott’s freedom to make a sweeping and momentous judgment about the status of Black people, both free and enslaved. Per the court, Black people could never be citizens of the United States. Further, the court ruled that Congress had no authority to stop or limit the spread of slavery into American territories. This proslavery ruling explicitly made the Missouri Compromise unconstitutional; implicitly, it made Douglas’s popular sovereignty unconstitutional. Defining American Roger Taney on Dred Scott v. Sandford In 1857, the United States Supreme Court ended years of legal battles when it ruled that Dred Scott, an enslaved person who had resided in several free states, should remain enslaved. The decision, written by Chief Justice Roger Taney, also stated that Black people could not be citizens and that Congress had no power to limit the spread of slavery. The excerpt below is from Taney’s decision. A free negro of the African race, whose ancestors were brought to this country and sold as slaves, is not a “citizen” within the meaning of the Constitution of the United States. . . . The only two clauses in the Constitution which point to this race treat them as persons whom it was morally lawfully to deal in as articles of property and to hold as slaves. . . . Every citizen has a right to take with him into the Territory any article of property which the Constitution of the United States recognises as property. . . . The Constitution of the United States recognises slaves as property, and pledges the Federal Government to protect it. And Congress cannot exercise any more authority over property of that description than it may constitutionally exercise over property of any other kind. . . . Prohibiting a citizen of the United States from taking with him his slaves when he removes to the Territory . . . is an exercise of authority over private property which is not warranted by the Constitution, and the removal of the plaintiff [Dred Scott] by his owner to that Territory gave him no title to freedom. How did the Supreme Court define Dred Scott? How did the court interpret the Constitution on this score? The Dred Scott decision infuriated Republicans by rendering their goal—to prevent slavery’s spread into the territories—unconstitutional. To Republicans, the decision offered further proof of the reach of the South’s Slave Power, which now apparently extended even to the Supreme Court. The decision also complicated life for northern Democrats, especially Stephen Douglas, who could no longer sell popular sovereignty as a symbolic concession to southerners from northern voters. Few northerners favored slavery’s expansion westward. THE LINCOLN-DOUGLAS DEBATES The turmoil in Kansas, combined with the furor over the Dred Scott decision, provided the background for the 1858 senatorial contest in Illinois between Democratic senator Stephen Douglas and Republican hopeful Abraham Lincoln ( Figure 14.17 ). Lincoln and Douglas engaged in seven debates before huge crowds that met to hear the two men argue the central issue of slavery and its expansion. Newspapers throughout the United States published their speeches. Whereas Douglas already enjoyed national recognition, Lincoln remained largely unknown before the debates. These appearances provided an opportunity for him to raise his profile with both northerners and southerners. Douglas portrayed the Republican Party as an abolitionist effort—one that aimed to bring about miscegenation , or race-mixing through sexual relations or marriage. The “Black Republicans,” Douglas declared, posed a dangerous threat to the Constitution. Indeed, because Lincoln declared the nation could not survive if the slave state–free state division continued, Douglas claimed the Republicans aimed to destroy what the founders had created. For his part, Lincoln said: “A house divided against itself cannot stand. I believe this government cannot endure permanently half Slave and half Free. I do not expect the Union to be dissolved—I do not expect the house to fall—but I do expect it will cease to be divided. It will become all one thing, or all the other. Either the opponents of slavery will arrest the further spread of it, and place it where the public mind shall rest in the belief that it is in the course of ultimate extinction: or its advocates will push it forward till it shall became alike lawful in all the States—old as well as new, North as well as South.” Lincoln interpreted the Dred Scott decision and the Kansas-Nebraska Act as efforts to nationalize slavery: that is, to make it legal everywhere from New England to the Midwest and beyond. Defining American The Lincoln-Douglas Debates On August 21, 1858, Abraham Lincoln and Stephen Douglas met in Ottawa, Illinois, for the first of seven debates. People streamed into Ottawa from neighboring counties and from as far away as Chicago. Reporting on the event was strictly partisan, with each of the candidates’ supporters claiming victory for their candidate. In this excerpt, Lincoln addresses the issues of equality between Blacks and Whites. [A]nything that argues me into his idea of perfect social and political equality with the negro, is but a specious and fantastic arrangement of words, . . . I have no purpose, directly or indirectly, to interfere with the institution of slavery in the States where it exists. I believe I have no lawful right to do so, and I have no inclination to do so. I have no purpose to introduce political and social equality between the White and the Black races. There is a physical difference between the two, which, in my judgment, will probably forever forbid their living together upon the footing of perfect equality, . . . I, as well as Judge Douglas, am in favor of the race to which I belong having the superior position. . . . [N]otwithstanding all this, there is no reason in the world why the negro is not entitled to all the natural rights enumerated in the Declaration of Independence, the right to life, liberty, and the pursuit of happiness. I hold that he is as much entitled to these as the White man. . . . [I]n the right to eat the bread, without the leave of anybody else, which his own hand earns, he is my equal and the equal of Judge Douglas, and the equal of every living man. —Lincoln’s speech on August 21, 1858, in Ottawa, Illinois How would you characterize Lincoln’s position on equality between Blacks and Whites? What types of equality exist, according to Lincoln? During the debates, Lincoln demanded that Douglas explain whether or not he believed that the 1857 Supreme Court decision in the Dred Scott case trumped the right of a majority to prevent the expansion of slavery under the principle of popular sovereignty. Douglas responded to Lincoln during the second debate at Freeport, Illinois. In what became known as the Freeport Doctrine , Douglas adamantly upheld popular sovereignty, declaring: “It matters not what way the Supreme Court may hereafter decide as to the abstract question whether slavery may or may not go into a territory under the Constitution, the people have the lawful means to introduce it or exclude it as they please.” The Freeport Doctrine antagonized southerners who supported slavery, and caused a major rift in the Democratic Party. The doctrine did help Douglas in Illinois, however, where most voters opposed the further expansion of slavery. The Illinois legislature selected Douglas over Lincoln for the senate, but the debates had the effect of launching Lincoln into the national spotlight. Lincoln had argued that slavery was morally wrong, even as he accepted the racism inherent in slavery. He warned that Douglas and the Democrats would nationalize slavery through the policy of popular sovereignty. Though Douglas had survived the senate election challenge from Lincoln, his Freeport Doctrine damaged the political support he needed from the Southern Democrats. This helped him to lose the following presidential election, undermining the Democratic Party as a national force. 14.4 John Brown and the Election of 1860 Learning Objectives By the end of this section, you will be able to: Describe John Brown’s raid on Harpers Ferry and its results Analyze the results of the election of 1860 Events in the late 1850s did nothing to quell the country’s sectional unrest, and compromise on the issue of slavery appeared impossible. Lincoln’s 1858 speeches during his debates with Douglas made the Republican Party’s position well known; Republicans opposed the extension of slavery and believed a Slave Power conspiracy sought to nationalize the institution. They quickly gained political momentum and took control of the House of Representatives in 1858. Southern leaders were divided on how to respond to Republican success. Southern extremists, known as “ Fire-Eaters ,” openly called for secession. Others, like Mississippi senator Jefferson Davis, put forward a more moderate approach by demanding constitutional protection of slavery. JOHN BROWN In October 1859, the radical abolitionist John Brown and eighteen armed men, both Black and White, attacked the federal arsenal in Harpers Ferry , Virginia. They hoped to capture the weapons there and distribute them among enslaved people to begin a massive uprising that would bring an end to slavery. Brown had already demonstrated during the 1856 Pottawatomie attack in Kansas that he had no patience for the nonviolent approach preached by pacifist abolitionists like William Lloyd Garrison. Born in Connecticut in 1800, Brown ( Figure 14.18 ) spent much of his life in the North, moving from Ohio to Pennsylvania and then upstate New York as his various business ventures failed. To him, slavery appeared an unacceptable evil that must be purged from the land, and like his Puritan forebears, he believed in using the sword to defeat the ungodly. Brown had gone to Kansas in the 1850s in an effort to stop slavery, and there, he had perpetrated the killings at Pottawatomie. He told other abolitionists of his plan to take Harpers Ferry Armory and initiate a massive slave uprising. Some abolitionists provided financial support, while others, including Frederick Douglass, found the plot suicidal and refused to join. On October 16, 1859, Brown’s force easily took control of the federal armory, which was unguarded ( Figure 14.19 ). However, his vision of a mass uprising failed completely. Very few enslaved people lived in the area to rally to Brown’s side, and the group found themselves holed up in the armory’s engine house with townspeople taking shots at them. Federal troops, commanded by Colonel Robert E. Lee, soon captured Brown and his followers. On December 2, Brown was hanged by the state of Virginia for treason. John Brown’s raid on Harpers Ferry generated intense reactions in both the South and the North. Southerners grew especially apprehensive of the possibility of other violent plots. They viewed Brown as a terrorist bent on destroying their civilization, and support for secession grew. Their anxiety led several southern states to pass laws designed to prevent rebellions by the enslaved. It seemed that the worst fears of the South had come true: A hostile majority would stop at nothing to destroy slavery. Was it possible, one resident of Maryland asked, to “live under a government, a majority of whose subjects or citizens regard John Brown as a martyr and Christian hero?” Many antislavery northerners did in fact consider Brown a martyr to the cause, and those who viewed slavery as a sin saw easy comparisons between him and Jesus Christ. THE ELECTION OF 1860 The election of 1860 threatened American democracy when the elevation of Abraham Lincoln to the presidency inspired secessionists in the South to withdraw their states from the Union. Lincoln’s election owed much to the disarray in the Democratic Party. The Dred Scott decision and the Freeport Doctrine had opened up huge sectional divisions among Democrats. Though Brown did not intend it, his raid had furthered the split between northern and southern Democrats. Fire-Eaters vowed to prevent a northern Democrat, especially Illinois’s Stephen Douglas, from becoming their presidential candidate. These proslavery zealots insisted on a southern Democrat. The Democratic nominating convention met in April 1860 in Charleston, South Carolina. However, it broke up after northern Democrats, who made up a majority of delegates, rejected Jefferson Davis’s efforts to protect slavery in the territories. These northern Democratic delegates knew that supporting Davis on this issue would be very unpopular among the people in their states. A second conference, held in Baltimore, further illustrated the divide within the Democratic Party. Northern Democrats nominated Stephen Douglas, while southern Democrats, who met separately, put forward Vice President John Breckinridge from Kentucky. The Democratic Party had fractured into two competing sectional factions. By offering two candidates for president, the Democrats gave the Republicans an enormous advantage. Also hoping to prevent a Republican victory, pro-Unionists from the border states organized the Constitutional Union Party and put up a fourth candidate, John Bell, for president, who pledged to end slavery agitation and preserve the Union but never fully explained how he’d accomplish this objective. In a pro-Lincoln political cartoon of the time ( Figure 14.20 ), the presidential election is presented as a baseball game. Lincoln stands on home plate. A skunk raises its tail at the other candidates. Holding his nose, southern Democrat John Breckinridge holds a bat labeled “Slavery Extension” and declares “I guess I’d better leave for Kentucky, for I smell something strong around here, and begin to think, that we are completely skunk’d.” The Republicans nominated Lincoln, and in the November election, he garnered a mere 40 percent of the popular vote, though he won every northern state except New Jersey. (Lincoln’s name was blocked from even appearing on many southern states’ ballots by southern Democrats.) More importantly, Lincoln did gain a majority in the Electoral College ( Figure 14.21 ). The Fire-Eaters, however, refused to accept the results. With South Carolina leading the way, Fire-Eaters in southern states began to withdraw formally from the United States in 1860. South Carolinian Mary Boykin Chesnut wrote in her diary about the reaction to the Lincoln’s election. “Now that the Black radical Republicans have the power,” she wrote, “I suppose they will Brown us all.” Her statement revealed many southerners’ fear that with Lincoln as President, the South could expect more mayhem like the John Brown raid.
biology
Chapter Outline 28.1 Phylum Porifera 28.2 Phylum Cnidaria 28.3 Superphylum Lophotrochozoa 28.4 Superphylum Ecdysozoa 28.5 Superphylum Deuterostomia Introduction A brief look at any magazine pertaining to our natural world, such as National Geographic , would show a rich variety of vertebrates, especially mammals and birds. To most people, these are the animals that attract our attention. Concentrating on vertebrates, however, gives us a rather biased and limited view of biodiversity, because it ignores nearly 97 percent of the animal kingdom, namely the invertebrates. Invertebrate animals are those without a cranium and defined vertebral column or spine. In addition to lacking a spine, most invertebrates also lack an endoskeleton. A large number of invertebrates are aquatic animals, and scientific research suggests that many of the world’s species are aquatic invertebrates that have not yet been documented.
[ { "answer": { "ans_choice": 1, "ans_text": "a collagen-like gel and suspended cells for various functions" }, "bloom": null, "hl_context": "While sponges ( excluding the hexactinellids ) do not exhibit tissue-layer organization , they do have different cell types that perform distinct functions . Pinacocytes , which are epithelial-like cells , form the outermost layer of sponges and enclose a jelly-like substance called mesohyl . <hl> Mesohyl is an extracellular matrix consisting of a collagen-like gel with suspended cells that perform various functions . <hl> The gel-like consistency of mesohyl acts like an endoskeleton and maintains the tubular morphology of sponges . In addition to the osculum , sponges have multiple pores called ostia on their bodies that allow water to enter the sponge . In some sponges , ostia are formed by porocytes , single tube-shaped cells that act as valves to regulate the flow of water into the spongocoel . In other sponges , ostia are formed by folds in the body wall of the sponge . Choanocytes ( “ collar cells ” ) are present at various locations , depending on the type of sponge , but they always line the inner portions of some space through which water flows ( the spongocoel in simple sponges , canals within the body wall in more complex sponges , and chambers scattered throughout the body in the most complex sponges ) . Whereas pinacocytes line the outside of the sponge , choanocytes tend to line certain inner portions of the sponge body that surround the mesohyl . The structure of a choanocyte is critical to its function , which is to generate a water current through the sponge and to trap and ingest food particles by phagocytosis . Note the similarity in appearance between the sponge choanocyte and choanoflagellates ( Protista ) . This similarity suggests that sponges and choanoflagellates are closely related and likely share a recent common ancestry . The cell body is embedded in mesohyl and contains all organelles required for normal cell function , but protruding into the “ open space ” inside of the sponge is a mesh-like collar composed of microvilli with a single flagellum in the center of the column . The cumulative effect of the flagella from all choanocytes aids the movement of water through the sponge : drawing water into the sponge through the numerous ostia , into the spaces lined by choanocytes , and eventually out through the osculum ( or osculi ) . In the meantime , food particles , including waterborne bacteria and algae , are trapped by the sieve-like collar of the choanocytes , slide down into the body of the cell , are ingested by phagocytosis , and become encased in a food vacuole . Lastly , choanocytes will differentiate into sperm for sexual reproduction , where they will become dislodged from the mesohyl and leave the sponge with expelled water through the osculum . Link to Learning", "hl_sentences": "Mesohyl is an extracellular matrix consisting of a collagen-like gel with suspended cells that perform various functions .", "question": { "cloze_format": "Mesohyl contains ___.", "normal_format": "What does Mesohyl contain?", "question_choices": [ "a polysaccharide gel and dead cells", "a collagen-like gel and suspended cells for various functions", "spicules composed of silica or calcium carbonate", "multiple pores" ], "question_id": "fs-idp46230224", "question_text": "Mesohyl contains:" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 3, "ans_text": "osculum" }, "bloom": null, "hl_context": "The invertebrates , or invertebrata , are animals that do not contain bony structures , such as the cranium and vertebrae . <hl> The simplest of all the invertebrates are the Parazoans , which include only the phylum Porifera : the sponges ( Figure 28.2 ) . <hl> Parazoans ( “ beside animals ” ) do not display tissue-level organization , although they do have specialized cells that perform specific functions . Sponge larvae are able to swim ; however , adults are non-motile and spend their life attached to a substratum . Since water is vital to sponges for excretion , feeding , and gas exchange , their body structure facilitates the movement of water through the sponge . Structures such as canals , chambers , and cavities enable water to move through the sponge to nearly all body cells . Morphology of Sponges The morphology of the simplest sponges takes the shape of a cylinder with a large central cavity , the spongocoel , occupying the inside of the cylinder . Water can enter into the spongocoel from numerous pores in the body wall . <hl> Water entering the spongocoel is extruded via a large common opening called the osculum . <hl> However , sponges exhibit a range of diversity in body forms , including variations in the size of the spongocoel , the number of osculi , and where the cells that filter food from the water are located .", "hl_sentences": "The simplest of all the invertebrates are the Parazoans , which include only the phylum Porifera : the sponges ( Figure 28.2 ) . Water entering the spongocoel is extruded via a large common opening called the osculum .", "question": { "cloze_format": "The large central opening in the Parazoan body is called the ___ .", "normal_format": "What is called the large central opening in the Parazoan body?", "question_choices": [ "gemmule", "spicule", "ostia", "osculum" ], "question_id": "fs-idp206434368", "question_text": "The large central opening in the Parazoan body is called the:" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 3, "ans_text": "phylum Cnidaria" }, "bloom": null, "hl_context": "<hl> Cnidarians contain specialized cells known as cnidocytes ( “ stinging cells ” ) containing organelles called nematocysts ( stingers ) . <hl> These cells are present around the mouth and tentacles , and serve to immobilize prey with toxins contained within the cells . Nematocysts contain coiled threads that may bear barbs . The outer wall of the cell has hairlike projections called cnidocils , which are sensitive to touch . When touched , the cells are known to fire coiled threads that can either penetrate the flesh of the prey or predators of cnidarians ( see Figure 28.5 ) or ensnare it . These coiled threads release toxins into the target and can often immobilize prey or scare away predators . <hl> Phylum Cnidaria includes animals that show radial or biradial symmetry and are diploblastic , that is , they develop from two embryonic layers . <hl> Nearly all ( about 99 percent ) cnidarians are marine species .", "hl_sentences": "Cnidarians contain specialized cells known as cnidocytes ( “ stinging cells ” ) containing organelles called nematocysts ( stingers ) . Phylum Cnidaria includes animals that show radial or biradial symmetry and are diploblastic , that is , they develop from two embryonic layers .", "question": { "cloze_format": "Cnidocytes are found in _____.", "normal_format": "Where are cnidocytes found?", "question_choices": [ "phylum Porifera", "phylum Nemertea", "phylum Nematoda", "phylum Cnidaria" ], "question_id": "fs-idm87789664", "question_text": "Cnidocytes are found in _____." }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 2, "ans_text": "polymorphs" }, "bloom": null, "hl_context": "Hydrozoa includes nearly 3,200 species ; most are marine , although some freshwater species are known ( Figure 28.12 ) . <hl> Animals in this class are polymorphs , and most exhibit both polypoid and medusoid forms in their lifecycle , although this is variable . <hl> The cubozoans contain muscular pads called pedalia at the corners of the square bell canopy , with one or more tentacles attached to each pedalium . These animals are further classified into orders based on the presence of single or multiple tentacles per pedalium . In some cases , the digestive system may extend into the pedalia . Nematocysts may be arranged in a spiral configuration along the tentacles ; this arrangement helps to effectively subdue and capture prey . <hl> Cubozoans exist in a polypoid form that develops from a planula larva . <hl> These polyps show limited mobility along the substratum and , like scyphozoans , may bud to form more polyps to colonize a habitat . Polyp forms then transform into the medusoid forms .", "hl_sentences": "Animals in this class are polymorphs , and most exhibit both polypoid and medusoid forms in their lifecycle , although this is variable . Cubozoans exist in a polypoid form that develops from a planula larva .", "question": { "cloze_format": "Cubozoans are ________.", "normal_format": "What are cubozoans?", "question_choices": [ "polyps", "medusoids", "polymorphs", "sponges" ], "question_id": "fs-idm95293216", "question_text": "Cubozoans are ________." }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 1, "ans_text": "a true coelom" }, "bloom": null, "hl_context": "Anatomy The epidermis is protected by an acellular , external cuticle , but this is much thinner than the cuticle found in the ecdysozoans and does not require periodic shedding for growth . Circular as well as longitudinal muscles are located interior to the epidermis . Chitinous hairlike extensions , anchored in the epidermis and projecting from the cuticle , called setae / chaetae are present in every segment . <hl> Annelids show the presence of a true coelom , derived from embryonic mesoderm and protostomy . <hl> Hence , they are the most advanced worms . A well-developed and complete digestive system is present in earthworms ( oligochaetes ) with a mouth , muscular pharynx , esophagus , crop , and gizzard being present . The gizzard leads to the intestine and ends in an anal opening . A cross-sectional view of a body segment of an earthworm ( a terrestrial type of annelid ) is shown in Figure 28.29 ; each segment is limited by a membranous septum that divides the coelomic cavity into a series of compartments .", "hl_sentences": "Annelids show the presence of a true coelom , derived from embryonic mesoderm and protostomy .", "question": { "cloze_format": "Annelids have (a) ___ .", "normal_format": "What do annelids have?", "question_choices": [ "pseudocoelom", "a true coelom", "no coelom", "none of the above" ], "question_id": "fs-idm59022368", "question_text": "Annelids have a:" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 0, "ans_text": "monogeneans" }, "bloom": "2", "hl_context": "<hl> The monogeneans are ectoparasites , mostly of fish , with simple lifecycles that consist of a free-swimming larva that attaches to a fish to begin transformation to the parasitic adult form . <hl> The parasite has only one host and that host is usually only one species . The worms may produce enzymes that digest the host tissues or simply graze on surface mucus and skin particles . Most monogeneans are hermaphroditic , but the male gametes develop first and so cross-fertilization is quite common .", "hl_sentences": "The monogeneans are ectoparasites , mostly of fish , with simple lifecycles that consist of a free-swimming larva that attaches to a fish to begin transformation to the parasitic adult form .", "question": { "cloze_format": "The group of flatworms that are primarily ectoparasites of fish are ___.", "normal_format": "Which group of flatworms are primarily ectoparasites of fish?", "question_choices": [ "monogeneans", "trematodes", "cestodes", "turbellarians" ], "question_id": "fs-idp45710736", "question_text": "Which group of flatworms are primarily ectoparasites of fish?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 2, "ans_text": "phylum Mollusca" }, "bloom": null, "hl_context": "<hl> One of the functions of the mantle is to secrete the shell . <hl> <hl> Some bivalves like oysters and mussels possess the unique ability to secrete and deposit a calcareous nacre or “ mother of pearl ” around foreign particles that may enter the mantle cavity . <hl> This property has been commercially exploited to produce pearls . <hl> Phylum Mollusca is the predominant phylum in marine environments . <hl> <hl> It is estimated that 23 percent of all known marine species are mollusks ; there are over 75,000 described species , making them the second most diverse phylum of animals . <hl> The name “ mollusca ” signifies a soft body , since the earliest descriptions of mollusks came from observations of unshelled cuttlefish . Mollusks are predominantly a marine group of animals ; however , they are known to inhabit freshwater as well as terrestrial habitats . <hl> Mollusks display a wide range of morphologies in each class and subclass , but share a few key characteristics , including a muscular foot , a visceral mass containing internal organs , and a mantle that may or may not secrete a shell of calcium carbonate ( Figure 28.20 ) . <hl>", "hl_sentences": "One of the functions of the mantle is to secrete the shell . Some bivalves like oysters and mussels possess the unique ability to secrete and deposit a calcareous nacre or “ mother of pearl ” around foreign particles that may enter the mantle cavity . Phylum Mollusca is the predominant phylum in marine environments . It is estimated that 23 percent of all known marine species are mollusks ; there are over 75,000 described species , making them the second most diverse phylum of animals . Mollusks display a wide range of morphologies in each class and subclass , but share a few key characteristics , including a muscular foot , a visceral mass containing internal organs , and a mantle that may or may not secrete a shell of calcium carbonate ( Figure 28.20 ) .", "question": { "cloze_format": "A mantle and mantle cavity are present in the ___.", "normal_format": "Where are a mantle and mantle cavity are present in?", "question_choices": [ "phylum Echinodermata", "phylum Adversoidea", "phylum Mollusca", "phylum Nemertea\t" ], "question_id": "fs-idp91569040", "question_text": "A mantle and mantle cavity are present in:" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 1, "ans_text": "fluid-filled cavity" }, "bloom": null, "hl_context": "A unique characteristic of this phylum is the presence of a proboscis enclosed in a rhynchocoel . The proboscis serves to capture food and may be ornamented with barbs in some species . <hl> The rhynchocoel is a fluid-filled cavity that extends from the head to nearly two-thirds of the length of the gut in these animals ( Figure 28.19 ) . <hl> The proboscis may be extended or retracted by the retractor muscle attached to the wall of the rhynchocoel .", "hl_sentences": "The rhynchocoel is a fluid-filled cavity that extends from the head to nearly two-thirds of the length of the gut in these animals ( Figure 28.19 ) .", "question": { "cloze_format": "The rhynchocoel is a ________.", "normal_format": "What is the rhynchocoel?", "question_choices": [ "circulatory system", "fluid-filled cavity", "primitive excretory system", "proboscis" ], "question_id": "fs-idm93621056", "question_text": "The rhynchocoel is a ________." }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 2, "ans_text": "chitin" }, "bloom": null, "hl_context": "<hl> The cuticle of Nematodes is rich in collagen and a carbohydrate-protein polymer called chitin , and forms an external “ skeleton ” outside the epidermis . <hl> The cuticle also lines many of the organs internally , including the pharynx and rectum . The epidermis can be either a single layer of cells or a syncytium , which is a multinucleated cell formed from the fusion of uninucleated cells . The overall morphology of these worms is cylindrical , as seen in Figure 28.31 . The head is radially symmetrical . A mouth opening is present at the anterior end with three or six lips as well as teeth in some species in the form of cuticle extensions . Some nematodes may present other external modifications like rings , head shields , or warts . Rings , however , do not reflect true internal body segmentation . The mouth leads to a muscular pharynx and intestine , which leads to a rectum and anal opening at the posterior end . The muscles of nematodes differ from those of most animals : They have a longitudinal layer only , which accounts for the whip-like motion of their movement .", "hl_sentences": "The cuticle of Nematodes is rich in collagen and a carbohydrate-protein polymer called chitin , and forms an external “ skeleton ” outside the epidermis .", "question": { "cloze_format": "The nematode cuticle contains _____.", "normal_format": "What does the nematode cuticle contain?", "question_choices": [ "glucose", "skin cells", "chitin", "nerve cells" ], "question_id": "fs-idp224380144", "question_text": "The nematode cuticle contains _____." }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 0, "ans_text": "ecdysozoans" }, "bloom": null, "hl_context": "<hl> Crustaceans are the most dominant aquatic arthropods , since the total number of marine crustacean species stands at 67,000 , but there are also freshwater and terrestrial crustacean species . <hl> <hl> Krill , shrimp , lobsters , crabs , and crayfish are examples of crustaceans ( Figure 28.38 ) . <hl> <hl> Terrestrial species like the wood lice ( Armadillidium spp . ) <hl> <hl> ( also called pill bugs , rolly pollies , potato bugs , or isopods ) are also crustaceans , although the number of non-aquatic species in this subphylum is relatively low . <hl> The superphylum Ecdysozoa contains an incredibly large number of species . <hl> This is because it contains two of the most diverse animal groups : phylum Nematoda ( the roundworms ) and Phylum Arthropoda ( the arthropods ) . <hl> <hl> The most prominant distinguising feature of Ecdysozoans is their tough external covering called the cuticle . <hl> The cuticle provides a tough , but flexible exoskeleton tht protects these animals from water loss , predators and other aspects of the external environment . All members of this superphylum periodically molt , or shed their cuticle as they grow . After molting , they secrete a new cuticle that will last until their next growth phase . The process of molting and replacing the cuticle is called ecdysis , which is how the superphylum derived its name .", "hl_sentences": "Crustaceans are the most dominant aquatic arthropods , since the total number of marine crustacean species stands at 67,000 , but there are also freshwater and terrestrial crustacean species . Krill , shrimp , lobsters , crabs , and crayfish are examples of crustaceans ( Figure 28.38 ) . Terrestrial species like the wood lice ( Armadillidium spp . ) ( also called pill bugs , rolly pollies , potato bugs , or isopods ) are also crustaceans , although the number of non-aquatic species in this subphylum is relatively low . This is because it contains two of the most diverse animal groups : phylum Nematoda ( the roundworms ) and Phylum Arthropoda ( the arthropods ) . The most prominant distinguising feature of Ecdysozoans is their tough external covering called the cuticle .", "question": { "cloze_format": "Crustaceans are _____.", "normal_format": "What are crustaceans?", "question_choices": [ "ecdysozoans", "nematodes", "arachnids", "parazoans" ], "question_id": "fs-idm10567808", "question_text": "Crustaceans are _____." }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 1, "ans_text": "hexapods" }, "bloom": null, "hl_context": "Subphylum Hexapoda The name Hexapoda denotes the presence of six legs ( three pairs ) in these animals as differentiated from the number of pairs present in other arthropods . <hl> Hexapods are characterized by the presence of a head , thorax , and abdomen , constituting three tagma . <hl> The thorax bears the wings as well as six legs in three pairs . <hl> Many of the common insects we encounter on a daily basis — including ants , cockroaches , butterflies , and flies — are examples of Hexapoda . <hl>", "hl_sentences": "Hexapods are characterized by the presence of a head , thorax , and abdomen , constituting three tagma . Many of the common insects we encounter on a daily basis — including ants , cockroaches , butterflies , and flies — are examples of Hexapoda .", "question": { "cloze_format": "Flies are_______.", "normal_format": "What are flies?", "question_choices": [ "chelicerates", "hexapods", "arachnids", "crustaceans" ], "question_id": "fs-idp58039536", "question_text": "Flies are_______." }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 3, "ans_text": "pentaradial symmetry" }, "bloom": null, "hl_context": "<hl> Adult echinoderms exhibit pentaradial symmetry and have a calcareous endoskeleton made of ossicles , although the early larval stages of all echinoderms have bilateral symmetry . <hl> The endoskeleton is developed by epidermal cells and may possess pigment cells , giving vivid colors to these animals , as well as cells laden with toxins . Gonads are present in each arm . In echinoderms like sea stars , every arm bears two rows of tube feet on the oral side . These tube feet help in attachment to the substratum . These animals possess a true coelom that is modified into a unique circulatory system called a water vascular system . An interesting feature of these animals is their power to regenerate , even when over 75 percent of their body mass is lost .", "hl_sentences": "Adult echinoderms exhibit pentaradial symmetry and have a calcareous endoskeleton made of ossicles , although the early larval stages of all echinoderms have bilateral symmetry .", "question": { "cloze_format": "Echinoderms have _____.", "normal_format": "What do echinoderms have?", "question_choices": [ "triangular symmetry", "radial symmetry", "hexagonal symmetry", "pentaradial symmetry" ], "question_id": "fs-idp115289728", "question_text": "Echinoderms have _____." }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 2, "ans_text": "water" }, "bloom": null, "hl_context": "<hl> Echinoderms possess a unique ambulacral or water vascular system , consisting of a central ring canal and radial canals that extend along each arm . <hl> <hl> Water circulates through these structures and facilitates gaseous exchange as well as nutrition , predation , and locomotion . <hl> The water vascular system also projects from holes in the skeleton in the form of tube feet . These tube feet can expand or contract based on the volume of water present in the system of that arm . By using hydrostatic pressure , the animal can either protrude or retract the tube feet . Water enters the madreporite on the aboral side of the echinoderm . From there , it passes into the stone canal , which moves water into the ring canal . The ring canal connects the radial canals ( there are five in a pentaradial animal ) , and the radial canals move water into the ampullae , which have tube feet through which the water moves . By moving water through the unique water vascular system , the echinoderm can move and force open mollusk shells during feeding .", "hl_sentences": "Echinoderms possess a unique ambulacral or water vascular system , consisting of a central ring canal and radial canals that extend along each arm . Water circulates through these structures and facilitates gaseous exchange as well as nutrition , predation , and locomotion .", "question": { "cloze_format": "The circulatory fluid in echinoderms is _____.", "normal_format": "Which is the circulatory fluid in echinoderms?", "question_choices": [ "blood", "mesohyl", "water", "saline" ], "question_id": "fs-idp120703824", "question_text": "The circulatory fluid in echinoderms is _____." }, "references_are_paraphrase": null } ]
28
28.1 Phylum Porifera Learning Objectives By the end of this section, you will be able to: Describe the organizational features of the simplest multicellular organisms Explain the various body forms and bodily functions of sponges The invertebrates, or invertebrata , are animals that do not contain bony structures, such as the cranium and vertebrae. The simplest of all the invertebrates are the Parazoans, which include only the phylum Porifera : the sponges ( Figure 28.2 ). Parazoans (“beside animals”) do not display tissue-level organization, although they do have specialized cells that perform specific functions. Sponge larvae are able to swim; however, adults are non-motile and spend their life attached to a substratum. Since water is vital to sponges for excretion, feeding, and gas exchange, their body structure facilitates the movement of water through the sponge. Structures such as canals, chambers, and cavities enable water to move through the sponge to nearly all body cells. Morphology of Sponges The morphology of the simplest sponges takes the shape of a cylinder with a large central cavity, the spongocoel , occupying the inside of the cylinder. Water can enter into the spongocoel from numerous pores in the body wall. Water entering the spongocoel is extruded via a large common opening called the osculum . However, sponges exhibit a range of diversity in body forms, including variations in the size of the spongocoel, the number of osculi, and where the cells that filter food from the water are located. While sponges (excluding the hexactinellids) do not exhibit tissue-layer organization, they do have different cell types that perform distinct functions. Pinacocytes , which are epithelial-like cells, form the outermost layer of sponges and enclose a jelly-like substance called mesohyl. Mesohyl is an extracellular matrix consisting of a collagen-like gel with suspended cells that perform various functions. The gel-like consistency of mesohyl acts like an endoskeleton and maintains the tubular morphology of sponges. In addition to the osculum, sponges have multiple pores called ostia on their bodies that allow water to enter the sponge. In some sponges, ostia are formed by porocytes, single tube-shaped cells that act as valves to regulate the flow of water into the spongocoel. In other sponges, ostia are formed by folds in the body wall of the sponge. Choanocytes (“collar cells”) are present at various locations, depending on the type of sponge, but they always line the inner portions of some space through which water flows (the spongocoel in simple sponges, canals within the body wall in more complex sponges, and chambers scattered throughout the body in the most complex sponges). Whereas pinacocytes line the outside of the sponge, choanocytes tend to line certain inner portions of the sponge body that surround the mesohyl. The structure of a choanocyte is critical to its function, which is to generate a water current through the sponge and to trap and ingest food particles by phagocytosis. Note the similarity in appearance between the sponge choanocyte and choanoflagellates (Protista). This similarity suggests that sponges and choanoflagellates are closely related and likely share a recent common ancestry. The cell body is embedded in mesohyl and contains all organelles required for normal cell function, but protruding into the “open space” inside of the sponge is a mesh-like collar composed of microvilli with a single flagellum in the center of the column. The cumulative effect of the flagella from all choanocytes aids the movement of water through the sponge: drawing water into the sponge through the numerous ostia, into the spaces lined by choanocytes, and eventually out through the osculum (or osculi). In the meantime, food particles, including waterborne bacteria and algae, are trapped by the sieve-like collar of the choanocytes, slide down into the body of the cell, are ingested by phagocytosis, and become encased in a food vacuole. Lastly, choanocytes will differentiate into sperm for sexual reproduction, where they will become dislodged from the mesohyl and leave the sponge with expelled water through the osculum. Link to Learning Watch this video to see the movement of water through the sponge body. Click to view content The second crucial cells in sponges are called amoebocytes (or archaeocytes), named for the fact that they move throughout the mesohyl in an amoeba-like fashion. Amoebocytes have a variety of functions: delivering nutrients from choanocytes to other cells within the sponge, giving rise to eggs for sexual reproduction (which remain in the mesohyl), delivering phagocytized sperm from choanocytes to eggs, and differentiating into more-specific cell types. Some of these more-specific cell types include collencytes and lophocytes, which produce the collagen-like protein to maintain the mesohyl, sclerocytes, which produce spicules in some sponges, and spongocytes, which produce the protein spongin in the majority of sponges. These cells produce collagen to maintain the consistency of the mesohyl. The different cell types in sponges are shown in Figure 28.3 . Visual Connection Which of the following statements is false? Choanocytes have flagella that propel water through the body. Pinacocytes can transform into any cell type. Lophocytes secrete collagen. Porocytes control the flow of water through pores in the sponge body. In some sponges, sclerocytes secrete small spicules into the mesohyl, which are composed of either calcium carbonate or silica, depending on the type of sponge. These spicules serve to provide additional stiffness to the body of the sponge. Additionally, spicules, when present externally, may ward off predators. Another type of protein, spongin, may also be present in the mesohyl of some sponges. Link to Learning Take an up-close tour through the sponge and its cells. The presence and composition of spicules/spongin are the differentiating characteristics of the three classes of sponges ( Figure 28.4 ): Class Calcarea contains calcium carbonate spicules and no spongin, class Hexactinellida contains six-rayed siliceous spicules and no spongin, and class Demospongia contains spongin and may or may not have spicules; if present, those spicules are siliceous. Spicules are most conspicuously present in class Hexactinellida, the order consisting of glass sponges. Some of the spicules may attain giant proportions (in relation to the typical size range of glass sponges of 3 to 10 mm) as seen in Monorhaphis chuni , which grows up to 3 m long. Link to Learning Use the Interactive Sponge Guide to identify species of sponges based on their external form, mineral skeleton, fiber, and skeletal architecture. Physiological Processes in Sponges Sponges, despite being simple organisms, regulate their different physiological processes through a variety of mechanisms. These processes regulate their metabolism, reproduction, and locomotion. Digestion Sponges lack complex digestive, respiratory, circulatory, reproductive, and nervous systems. Their food is trapped when water passes through the ostia and out through the osculum. Bacteria smaller than 0.5 microns in size are trapped by choanocytes, which are the principal cells engaged in nutrition, and are ingested by phagocytosis. Particles that are larger than the ostia may be phagocytized by pinacocytes. In some sponges, amoebocytes transport food from cells that have ingested food particles to those that do not. For this type of digestion, in which food particles are digested within individual cells, the sponge draws water through diffusion. The limit of this type of digestion is that food particles must be smaller than individual cells. All other major body functions in the sponge (gas exchange, circulation, excretion) are performed by diffusion between the cells that line the openings within the sponge and the water that is passing through those openings. All cell types within the sponge obtain oxygen from water through diffusion. Likewise, carbon dioxide is released into seawater by diffusion. In addition, nitrogenous waste produced as a byproduct of protein metabolism is excreted via diffusion by individual cells into the water as it passes through the sponge. Reproduction Sponges reproduce by sexual as well as asexual methods. The typical means of asexual reproduction is either fragmentation (where a piece of the sponge breaks off, settles on a new substrate, and develops into a new individual) or budding (a genetically identical outgrowth grows from the parent and eventually detaches or remains attached to form a colony). An atypical type of asexual reproduction is found only in freshwater sponges and occurs through the formation of gemmules. Gemmules are environmentally resistant structures produced by adult sponges wherein the typical sponge morphology is inverted. In gemmules, an inner layer of amoebocytes is surrounded by a layer of collagen (spongin) that may be reinforced by spicules. The collagen that is normally found in the mesohyl becomes the outer protective layer. In freshwater sponges, gemmules may survive hostile environmental conditions like changes in temperature and serve to recolonize the habitat once environmental conditions stabilize. Gemmules are capable of attaching to a substratum and generating a new sponge. Since gemmules can withstand harsh environments, are resistant to desiccation, and remain dormant for long periods, they are an excellent means of colonization for a sessile organism. Sexual reproduction in sponges occurs when gametes are generated. Sponges are monoecious (hermaphroditic), which means that one individual can produce both gametes (eggs and sperm) simultaneously. In some sponges, production of gametes may occur throughout the year, whereas other sponges may show sexual cycles depending upon water temperature. Sponges may also become sequentially hermaphroditic, producing oocytes first and spermatozoa later. Oocytes arise by the differentiation of amoebocytes and are retained within the spongocoel, whereas spermatozoa result from the differentiation of choanocytes and are ejected via the osculum. Ejection of spermatozoa may be a timed and coordinated event, as seen in certain species. Spermatozoa carried along by water currents can fertilize the oocytes borne in the mesohyl of other sponges. Early larval development occurs within the sponge, and free-swimming larvae are then released via the osculum. Locomotion Sponges are generally sessile as adults and spend their lives attached to a fixed substratum. They do not show movement over large distances like other free-swimming marine invertebrates. However, sponge cells are capable of creeping along substrata via organizational plasticity. Under experimental conditions, researchers have shown that sponge cells spread on a physical support demonstrate a leading edge for directed movement. It has been speculated that this localized creeping movement may help sponges adjust to microenvironments near the point of attachment. It must be noted, however, that this pattern of movement has been documented in laboratories, but it remains to be observed in natural sponge habitats. Link to Learning Watch this BBC video showing the array of sponges seen along the Cayman Wall during a submersible dive. 28.2 Phylum Cnidaria Learning Objectives By the end of this section, you will be able to: Compare structural and organization characteristics of Porifera and Cnidaria Describe the progressive development of tissues and their relevance to animal complexity Phylum Cnidaria includes animals that show radial or biradial symmetry and are diploblastic, that is, they develop from two embryonic layers. Nearly all (about 99 percent) cnidarians are marine species. Cnidarians contain specialized cells known as cnidocytes (“stinging cells”) containing organelles called nematocysts (stingers). These cells are present around the mouth and tentacles, and serve to immobilize prey with toxins contained within the cells. Nematocysts contain coiled threads that may bear barbs. The outer wall of the cell has hairlike projections called cnidocils, which are sensitive to touch. When touched, the cells are known to fire coiled threads that can either penetrate the flesh of the prey or predators of cnidarians (see Figure 28.5 ) or ensnare it. These coiled threads release toxins into the target and can often immobilize prey or scare away predators. Link to Learning View this video animation showing two anemones engaged in a battle. Click to view content Animals in this phylum display two distinct morphological body plans: polyp or “stalk” and medusa or “bell” ( Figure 28.6 ). An example of the polyp form is Hydra spp.; perhaps the most well-known medusoid animals are the jellies (jellyfish). Polyp forms are sessile as adults, with a single opening to the digestive system (the mouth) facing up with tentacles surrounding it. Medusa forms are motile, with the mouth and tentacles hanging down from an umbrella-shaped bell. Some cnidarians are polymorphic, that is, they have two body plans during their life cycle. An example is the colonial hydroid called an Obelia. The sessile polyp form has, in fact, two types of polyps, shown in Figure 28.7 . The first is the gastrozooid, which is adapted for capturing prey and feeding; the other type of polyp is the gonozooid, adapted for the asexual budding of medusa. When the reproductive buds mature, they break off and become free-swimming medusa, which are either male or female (dioecious). The male medusa makes sperm, whereas the female medusa makes eggs. After fertilization, the zygote develops into a blastula, which develops into a planula larva. The larva is free swimming for a while, but eventually attaches and a new colonial reproductive polyp is formed. Link to Learning Click here to follow the life cycle of the Obelia. All cnidarians show the presence of two membrane layers in the body that are derived from the endoderm and ectoderm of the embryo. The outer layer (from ectoderm) is called the epidermis and lines the outside of the animal, whereas the inner layer (from endoderm) is called the gastrodermis and lines the digestive cavity. Between these two membrane layers is a non-living, jelly-like mesoglea connective layer. In terms of cellular complexity, cnidarians show the presence of differentiated cell types in each tissue layer, such as nerve cells, contractile epithelial cells, enzyme-secreting cells, and nutrient-absorbing cells, as well as the presence of intercellular connections. However, the development of organs or organ systems is not advanced in this phylum. The nervous system is primitive, with nerve cells scattered across the body. This nerve net may show the presence of groups of cells in the form of nerve plexi (singular plexus) or nerve cords. The nerve cells show mixed characteristics of motor as well as sensory neurons. The predominant signaling molecules in these primitive nervous systems are chemical peptides, which perform both excitatory and inhibitory functions. Despite the simplicity of the nervous system, it coordinates the movement of tentacles, the drawing of captured prey to the mouth, the digestion of food, and the expulsion of waste. The cnidarians perform extracellular digestion in which the food is taken into the gastrovascular cavity, enzymes are secreted into the cavity, and the cells lining the cavity absorb nutrients. The gastrovascular cavity has only one opening that serves as both a mouth and an anus, which is termed an incomplete digestive system. Cnidarian cells exchange oxygen and carbon dioxide by diffusion between cells in the epidermis with water in the environment, and between cells in the gastrodermis with water in the gastrovascular cavity. The lack of a circulatory system to move dissolved gases limits the thickness of the body wall and necessitates a non-living mesoglea between the layers. There is no excretory system or organs, and nitrogenous wastes simply diffuse from the cells into the water outside the animal or in the gastrovascular cavity. There is also no circulatory system, so nutrients must move from the cells that absorb them in the lining of the gastrovascular cavity through the mesoglea to other cells. The phylum Cnidaria contains about 10,000 described species divided into four classes: Anthozoa, Scyphozoa, Cubozoa, and Hydrozoa. The anthozoans, the sea anemones and corals, are all sessile species, whereas the scyphozoans (jellyfish) and cubozoans (box jellies) are swimming forms. The hydrozoans contain sessile forms and swimming colonial forms like the Portuguese Man O’ War. Class Anthozoa The class Anthozoa includes all cnidarians that exhibit a polyp body plan only; in other words, there is no medusa stage within their life cycle. Examples include sea anemones ( Figure 28.8 ), sea pens, and corals, with an estimated number of 6,100 described species. Sea anemones are usually brightly colored and can attain a size of 1.8 to 10 cm in diameter. These animals are usually cylindrical in shape and are attached to a substrate. A mouth opening is surrounded by tentacles bearing cnidocytes. The mouth of a sea anemone is surrounded by tentacles that bear cnidocytes. The slit-like mouth opening and pharynx are lined by a groove called a siphonophore . The pharynx is the muscular part of the digestive system that serves to ingest as well as egest food, and may extend for up to two-thirds the length of the body before opening into the gastrovascular cavity. This cavity is divided into several chambers by longitudinal septa called mesenteries. Each mesentery consists of one ectodermal and one endodermal cell layer with the mesoglea sandwiched in between. Mesenteries do not divide the gastrovascular cavity completely, and the smaller cavities coalesce at the pharyngeal opening. The adaptive benefit of the mesenteries appears to be an increase in surface area for absorption of nutrients and gas exchange. Sea anemones feed on small fish and shrimp, usually by immobilizing their prey using the cnidocytes. Some sea anemones establish a mutualistic relationship with hermit crabs by attaching to the crab’s shell. In this relationship, the anemone gets food particles from prey caught by the crab, and the crab is protected from the predators by the stinging cells of the anemone. Anemone fish, or clownfish, are able to live in the anemone since they are immune to the toxins contained within the nematocysts. Anthozoans remain polypoid throughout their lives and can reproduce asexually by budding or fragmentation, or sexually by producing gametes. Both gametes are produced by the polyp, which can fuse to give rise to a free-swimming planula larva. The larva settles on a suitable substratum and develops into a sessile polyp. Class Scyphozoa Class Scyphozoa includes all the jellies and is exclusively a marine class of animals with about 200 known species. The defining characteristic of this class is that the medusa is the prominent stage in the life cycle, although there is a polyp stage present. Members of this species range from 2 to 40 cm in length but the largest scyphozoan species, Cyanea capillata , can reach a size of 2 m across. Scyphozoans display a characteristic bell-like morphology ( Figure 28.9 ). In the jellyfish, a mouth opening is present on the underside of the animal, surrounded by tentacles bearing nematocysts. Scyphozoans live most of their life cycle as free-swimming, solitary carnivores. The mouth leads to the gastrovascular cavity, which may be sectioned into four interconnected sacs, called diverticuli. In some species, the digestive system may be further branched into radial canals. Like the septa in anthozoans, the branched gastrovascular cells serve two functions: to increase the surface area for nutrient absorption and diffusion; thus, more cells are in direct contact with the nutrients in the gastrovascular cavity. In scyphozoans, nerve cells are scattered all over the body. Neurons may even be present in clusters called rhopalia. These animals possess a ring of muscles lining the dome of the body, which provides the contractile force required to swim through water. Scyphozoans are dioecious animals, that is, the sexes are separate. The gonads are formed from the gastrodermis and gametes are expelled through the mouth. Planula larvae are formed by external fertilization; they settle on a substratum in a polypoid form known as scyphistoma. These forms may produce additional polyps by budding or may transform into the medusoid form. The life cycle ( Figure 28.10 ) of these animals can be described as polymorphic , because they exhibit both a medusal and polypoid body plan at some point in their life cycle. Link to Learning Identify the life cycle stages of jellies using this video animation quiz from the New England Aquarium. Class Cubozoa This class includes jellies that have a box-shaped medusa, or a bell that is square in cross-section; hence, are colloquially known as “box jellyfish.” These species may achieve sizes of 15–25 cm. Cubozoans display overall morphological and anatomical characteristics that are similar to those of the scyphozoans. A prominent difference between the two classes is the arrangement of tentacles. This is the most venomous group of all the cnidarians ( Figure 28.11 ). The cubozoans contain muscular pads called pedalia at the corners of the square bell canopy, with one or more tentacles attached to each pedalium. These animals are further classified into orders based on the presence of single or multiple tentacles per pedalium. In some cases, the digestive system may extend into the pedalia. Nematocysts may be arranged in a spiral configuration along the tentacles; this arrangement helps to effectively subdue and capture prey. Cubozoans exist in a polypoid form that develops from a planula larva. These polyps show limited mobility along the substratum and, like scyphozoans, may bud to form more polyps to colonize a habitat. Polyp forms then transform into the medusoid forms. Class Hydrozoa Hydrozoa includes nearly 3,200 species; most are marine, although some freshwater species are known ( Figure 28.12 ). Animals in this class are polymorphs, and most exhibit both polypoid and medusoid forms in their lifecycle, although this is variable. The polyp form in these animals often shows a cylindrical morphology with a central gastrovascular cavity lined by the gastrodermis. The gastrodermis and epidermis have a simple layer of mesoglea sandwiched between them. A mouth opening, surrounded by tentacles, is present at the oral end of the animal. Many hydrozoans form colonies that are composed of a branched colony of specialized polyps that share a gastrovascular cavity, such as in the colonial hydroid Obelia . Colonies may also be free-floating and contain medusoid and polypoid individuals in the colony as in Physalia (the Portuguese Man O’ War) or Velella (By-the-wind sailor). Even other species are solitary polyps ( Hydra ) or solitary medusae ( Gonionemus ). The true characteristic shared by all of these diverse species is that their gonads for sexual reproduction are derived from epidermal tissue, whereas in all other cnidarians they are derived from gastrodermal tissue. 28.3 Superphylum Lophotrochozoa Learning Objectives By the end of this section, you will be able to: Describe the unique anatomical and morphological features of flatworms, rotifers, Nemertea, mollusks, and annelids Describe the development of an extracoelomic cavity Discuss the advantages of true body segmentation Explain the key features of Platyhelminthes and their importance as parasites Describe the features of animals classified in phylum Annelida Animals belonging to superphylum Lophotrochozoa are protostomes, in which the blastopore, or the point of involution of the ectoderm or outer germ layer, becomes the mouth opening to the alimentary canal. This is called protostomy or “first mouth.” In protostomy, solid groups of cells split from the endoderm or inner germ layer to form a central mesodermal layer of cells. This layer multiplies into a band and then splits internally to form the coelom; this protostomic coelom is hence termed schizocoelom . As lophotrochozoans, the organisms in this superphylum possess either a lophophore or trochophore larvae. The lophophores include groups that are united by the presence of the lophophore, a set of ciliated tentacles surrounding the mouth. Lophophorata include the flatworms and several other phyla. These clades are upheld when RNA sequences are compared. Trochophore larvae are characterized by two bands of cilia around the body. The lophotrochozoans are triploblastic and possess an embryonic mesoderm sandwiched between the ectoderm and endoderm found in the diploblastic cnidarians. These phyla are also bilaterally symmetrical, meaning that a longitudinal section will divide them into right and left sides that are symmetrical. It also means the beginning of cephalization, the evolution of a concentration of nervous tissues and sensory organs in the head of the organism, which is where it first encounters its environment. Phylum Platyhelminthes The flatworms are acoelomate organisms that include many free-living and parasitic forms. Most of the flatworms are classified in the superphylum Lophotrochozoa, which also includes the mollusks and annelids. The Platyhelminthes consist of two lineages: the Catenulida and the Rhabditophora. The Catenulida, or "chain worms" is a small clade of just over 100 species. These worms typically reproduce asexually by budding. However, the offspring do not fully attach from the parents and, resemble a chain in appearance. All of the remaining flatworms discussed here are part of the Rhabditophora. Many flatworms are parasitic, including important parasites of humans. Flatworms have three embryonic tissue layers that give rise to surfaces that cover tissues (from ectoderm), internal tissues (from mesoderm), and line the digestive system (from endoderm). The epidermal tissue is a single layer cells or a layer of fused cells (syncytium) that covers a layer of circular muscle above a layer of longitudinal muscle. The mesodermal tissues include mesenchymal cells that contain collagen and support secretory cells that secrete mucus and other materials at the surface. The flatworms are acoelomates, so their bodies are solid between the outer surface and the cavity of the digestive system. Physiological Processes of Flatworms The free-living species of flatworms are predators or scavengers. Parasitic forms feed on the tissues of their hosts. Most flatworms, such as the planarian shown in Figure 28.13 , have a gastrovascular cavity rather than a complete digestive system. In such animals, the “mouth” is also used to expel waste materials from the digestive system. Some species also have an anal opening. The gut may be a simple sac or highly branched. Digestion is extracellular, with digested materials taken in to the cells of the gut lining by phagocytosis. One group, the cestodes, lacks a digestive system. Flatworms have an excretory system with a network of tubules throughout the body with openings to the environment and nearby flame cells, whose cilia beat to direct waste fluids concentrated in the tubules out of the body. The system is responsible for the regulation of dissolved salts and the excretion of nitrogenous wastes. The nervous system consists of a pair of nerve cords running the length of the body with connections between them and a large ganglion or concentration of nerves at the anterior end of the worm, where there may also be a concentration of photosensory and chemosensory cells. There is neither a circulatory nor respiratory system, with gas and nutrient exchange dependent on diffusion and cell-cell junctions. This necessarily limits the thickness of the body in these organisms, constraining them to be “flat” worms. Most flatworm species are monoecious, and fertilization is typically internal. Asexual reproduction is common in some groups. Diversity of Flatworms Platyhelminthes are traditionally divided into four classes: Turbellaria, Monogenea, Trematoda, and Cestoda ( Figure 28.14 ). As discussed above, the relationships among members of these classes is being reassessed, with the turbellarians in particular now viewed as a paraphyletic group, a group that does not have a single common ancestor. The class Turbellaria includes mainly free-living, marine species, although some species live in freshwater or moist terrestrial environments. The ventral epidermis of turbellarians is ciliated and facilitates their locomotion. Some turbellarians are capable of remarkable feats of regeneration in which they may regrow the body, even from a small fragment. The monogeneans are ectoparasites, mostly of fish, with simple lifecycles that consist of a free-swimming larva that attaches to a fish to begin transformation to the parasitic adult form. The parasite has only one host and that host is usually only one species. The worms may produce enzymes that digest the host tissues or simply graze on surface mucus and skin particles. Most monogeneans are hermaphroditic, but the male gametes develop first and so cross-fertilization is quite common. The trematodes, or flukes, are internal parasites of mollusks and many other groups, including humans. Trematodes have complex lifecycles that involve a primary host in which sexual reproduction occurs, and one or more secondary hosts in which asexual reproduction occurs. The primary host is almost always a mollusk. Trematodes are responsible for serious human diseases including schistosomiasis, a blood fluke. The disease infects an estimated 200 million people in the tropics, leading to organ damage and chronic symptoms like fatigue. Infection occurs when the human enters the water and a larva, released from the primary snail host, locates and penetrates the skin. The parasite infects various organs in the body and feeds on red blood cells before reproducing. Many of the eggs are released in feces and find their way into a waterway, where they are able to reinfect the primary snail host. The cestodes, or tapeworms, are also internal parasites, mainly of vertebrates ( Figure 28.15 ). Tapeworms live in the intestinal tract of the primary host and remain fixed using a sucker on the anterior end, or scolex, of the tapeworm body. The remaining body of the tapeworm is made up of a long series of units called proglottids, each of which may contain an excretory system with flame cells, but contain reproductive structures, both male and female. Tapeworms do not possess a digestive system; instead, they absorb nutrients from the food matter passing them in the host’s intestine. Proglottids are produced at the scolex and gradually migrate to the end of the tapeworm; at this point, they are “mature” and all structures except fertilized eggs have degenerated. Most reproduction occurs by cross-fertilization. The proglottid detaches from the body of the worm and is released into the feces of the organism. The eggs are eaten by an intermediate host. The juvenile worm infects the intermediate host and takes up residence, usually in muscle tissue. When the muscle tissue is eaten by the primary host, the cycle is completed. There are several tapeworm parasites of humans that are transmitted by eating uncooked or poorly cooked pork, beef, and fish. Phylum Rotifera The rotifers are a microscopic (about 100 µm to 30 mm) group of mostly aquatic organisms that get their name from the corona , a rotating, wheel-like structure that is covered with cilia at their anterior end ( Figure 28.16 ). Although their taxonomy is currently in flux, one treatment places the rotifers in three classes: Bdelloidea, Monogononta, and Seisonidea. The classification of the group is currently under revision, however, as more phylogenetic evidence becomes available. It is possible that the “spiny headed worms” currently in phylum Acanthocephala will be incorporated into this group in the future. The body form of rotifers consists of a head (which contains the corona), a trunk (which contains the organs), and the foot. Rotifers are typically free-swimming and truly planktonic organisms, but the toes or extensions of the foot can secrete a sticky material forming a holdfast to help them adhere to surfaces. The head contains sensory organs in the form of a bi-lobed brain and small eyespots near the corona. The rotifers are filter feeders that will eat dead material, algae, and other microscopic living organisms, and are therefore very important components of aquatic food webs. Rotifers obtain food that is directed toward the mouth by the current created from the movement of the corona. The food particles enter the mouth and travel to the mastax (pharynx with jaw-like structures). Food then passes by digestive and salivary glands, and into the stomach, then onto the intestines. Digestive and excretory wastes are collected in a cloacal bladder before being released out the anus. Link to Learning Watch this video to see rotifers feeding. Rotifers are pseudocoelomates commonly found in fresh water and some salt water environments throughout the world. Figure 28.17 shows the anatomy of a rotifer belonging to class Bdelloidea. About 2,200 species of rotifers have been identified. Rotifers are dioecious organisms (having either male or female genitalia) and exhibit sexual dimorphism (males and females have different forms). Many species are parthenogenic and exhibit haplodiploidy, a method of sex determination in which a fertilized egg develops into a female and an unfertilized egg develops into a male. In many dioecious species, males are short-lived and smaller with no digestive system and a single testis. Females can produce eggs that are capable of dormancy for protection during harsh environmental conditions. Phylum Nemertea The Nemertea are colloquially known as ribbon worms. Most species of phylum Nemertea are marine, predominantly benthic or bottom dwellers, with an estimated 900 species known. However, nemertini have been recorded in freshwater and terrestrial habitats as well. Most nemerteans are carnivores, feeding on worms, clams, and crustaceans. Some species are scavengers, and some nemertini species, like Malacobdella grossa , have also evolved commensalistic relationships with some mollusks. Some species have devastated commercial fishing of clams and crabs. Nemerteans have almost no predators and two species are sold as fish bait. Morphology Ribbon worms vary in size from 1 cm to several meters. They show bilateral symmetry and remarkable contractile properties. Because of their contractility, they can change their morphological presentation in response to environmental cues. Animals in phylum Nemertea show a flattened morphology, that is, they are flat from front to back, like a flattened tube. Nemertea are soft and unsegmented animals ( Figure 28.18 ). A unique characteristic of this phylum is the presence of a proboscis enclosed in a rhynchocoel . The proboscis serves to capture food and may be ornamented with barbs in some species. The rhynchocoel is a fluid-filled cavity that extends from the head to nearly two-thirds of the length of the gut in these animals ( Figure 28.19 ). The proboscis may be extended or retracted by the retractor muscle attached to the wall of the rhynchocoel. Link to Learning Watch this video to see a nemertean attack a polychaete with its proboscis. Click to view content Digestive System The nemertini show a very well-developed digestive system. A mouth opening that is ventral to the rhynchocoel leads into the foregut, followed by the intestine. The intestine is present in the form of diverticular pouches and ends in a rectum that opens via an anus. Gonads are interspersed with the intestinal diverticular pouches and open outwards via genital pores. A circulatory system consists of a closed loop of a pair of lateral blood vessels. The circulatory system is derived from the coelomic cavity of the embryo. Some animals may also have cross-connecting vessels in addition to lateral ones. Although these are called blood vessels, since they are of coelomic origin, the circulatory fluid is colorless. Some species bear hemoglobin as well as other yellow or green pigments. The blood vessels are connected to the rhynchocoel. The flow of fluid in these vessels is facilitated by the contraction of muscles in the body wall. A pair of protonephridia, or primitive kidneys, is present in these animals to facilitate osmoregulation. Gaseous exchange occurs through the skin in the nemertini. Nervous System Nemertini have a ganglion or “brain” situated at the anterior end between the mouth and the foregut, surrounding the digestive system as well as the rhynchocoel. A ring of four nerve masses called “ganglia” composes the brain in these animals. Paired longitudinal nerve cords emerge from the brain ganglia and extend to the posterior end. Ocelli or eyespots are present in pairs, in multiples of two in the anterior portion of the body. It is speculated that the eyespots originate from neural tissue and not from the epidermis. Reproduction Animals in phylum Nemertea show sexual dimorphism, although freshwater species may be hermaphroditic. Eggs and sperm are released into the water, and fertilization occurs externally. The zygote then develops into a planuliform larva. In some nemertine species, a pilidium larva may develop inside the young worm, from a series of imaginal discs. This larval form, characteristically shaped like a deerstalker cap, devours tissues from the young worm for survival before metamorphosing into the adult-like morphology. Phylum Mollusca Phylum Mollusca is the predominant phylum in marine environments. It is estimated that 23 percent of all known marine species are mollusks; there are over 75,000 described species, making them the second most diverse phylum of animals. The name “mollusca” signifies a soft body, since the earliest descriptions of mollusks came from observations of unshelled cuttlefish. Mollusks are predominantly a marine group of animals; however, they are known to inhabit freshwater as well as terrestrial habitats. Mollusks display a wide range of morphologies in each class and subclass, but share a few key characteristics, including a muscular foot, a visceral mass containing internal organs, and a mantle that may or may not secrete a shell of calcium carbonate ( Figure 28.20 ). Visual Connection Which of the following statements about the anatomy of a mollusk is false? Mollusks have a radula for grinding food. A digestive gland is connected to the stomach. The tissue beneath the shell is called the mantle. The digestive system includes a gizzard, a stomach, a digestive gland, and the intestine. Mollusks have a muscular foot, which is used for locomotion and anchorage, and varies in shape and function, depending on the type of mollusk under study. In shelled mollusks, this foot is usually the same size as the opening of the shell. The foot is a retractable as well as an extendable organ. The foot is the ventral-most organ, whereas the mantle is the limiting dorsal organ. Mollusks are eucoelomate, but the coelomic cavity is restricted to a cavity around the heart in adult animals. The mantle cavity develops independently of the coelomic cavity. The visceral mass is present above the foot, in the visceral hump. This includes digestive, nervous, excretory, reproductive, and respiratory systems. Mollusk species that are exclusively aquatic have gills for respiration, whereas some terrestrial species have lungs for respiration. Additionally, a tongue-like organ called a radula , which bears chitinous tooth-like ornamentation, is present in many species, and serves to shred or scrape food. The mantle (also known as the pallium) is the dorsal epidermis in mollusks; shelled mollusks are specialized to secrete a chitinous and hard calcareous shell. Most mollusks are dioecious animals and fertilization occurs externally, although this is not the case in terrestrial mollusks, such as snails and slugs, or in cephalopods. In some mollusks, the zygote hatches and undergoes two larval stages— trochophore and veliger —before becoming a young adult; bivalves may exhibit a third larval stage, glochidia. Classification of Phylum Mollusca Phylum Mollusca is a very diverse (85,000 species) group of mostly marine species. Mollusks have a dramatic variety of form, ranging from large predatory squids and octopus, some of which show a high degree of intelligence, to grazing forms with elaborately sculpted and colored shells. This phylum can be segregated into seven classes: Aplacophora, Monoplacophora, Polyplacophora, Bivalvia, Gastropoda, Cephalopoda, and Scaphopoda. Class Aplacophora (“bearing no plates”) includes worm-like animals primarily found in benthic marine habitats. These animals lack a calcareous shell but possess aragonite spicules on their epidermis. They have a rudimentary mantle cavity and lack eyes, tentacles, and nephridia (excretory organs). Members of class Monoplacophora (“bearing one plate”) posses a single, cap-like shell that encloses the body. The morphology of the shell and the underlying animal can vary from circular to ovate. A looped digestive system, multiple pairs of excretory organs, many gills, and a pair of gonads are present in these animals. The monoplacophorans were believed extinct and only known via fossil records until the discovery of Neopilina galathaea in 1952. Today, scientists have identified nearly two dozen extant species. Animals in the class Polyplacophora (“bearing many plates”) are commonly known as “chitons” and bear an armor-like eight-plated shell ( Figure 28.21 ). These animals have a broad, ventral foot that is adapted for suction to rocks and other substrates, and a mantle that extends beyond the shell in the form of a girdle. Calcareous spines may be present on the girdle to offer protection from predators. Respiration is facilitated by ctenidia (gills) that are present ventrally. These animals possess a radula that is modified for scraping. The nervous system is rudimentary with only buccal or “cheek” ganglia present at the anterior end. Eyespots are absent in these animals. A single pair of nephridia for excretion is present. Class Bivalvia (“two shells”) includes clams, oysters, mussels, scallops, and geoducks. Members of this class are found in marine as well as freshwater habitats. As the name suggests, bivalves are enclosed in a pair of shells (valves are commonly called “shells”) that are hinged at the dorsal end by shell ligaments as well as shell teeth ( Figure 28.22 ). The overall morphology is laterally flattened, and the head region is poorly developed. Eyespots and statocysts may be absent in some species. Since these animals are suspension feeders, a radula is absent in this class of mollusks. Respiration is facilitated by a pair of ctenidia, whereas excretion and osmoregulation are brought about by a pair of nephridia. Bivalves often possess a large mantle cavity. In some species, the posterior edges of the mantle may fuse to form two siphons that serve to take in and exude water. One of the functions of the mantle is to secrete the shell. Some bivalves like oysters and mussels possess the unique ability to secrete and deposit a calcareous nacre or “mother of pearl” around foreign particles that may enter the mantle cavity. This property has been commercially exploited to produce pearls. Link to Learning Watch the animations of bivalves feeding: View the process in clams and mussels at these sites. Animals in class Gastropoda (“stomach foot”) include well-known mollusks like snails, slugs, conchs, sea hares, and sea butterflies. Gastropoda includes shell-bearing species as well as species with a reduced shell. These animals are asymmetrical and usually present a coiled shell ( Figure 28.23 ). Shells may be planospiral (like a garden hose wound up), commonly seen in garden snails, or conispiral , (like a spiral staircase), commonly seen in marine conches. The visceral mass in the shelled species displays torsion around the perpendicular axis on the center of the foot, which is the key characteristic of this group, along with a foot that is modified for crawling ( Figure 28.24 ). Most gastropods bear a head with tentacles, eyes, and a style. A complex radula is used by the digestive system and aids in the ingestion of food. Eyes may be absent in some gastropods species. The mantle cavity encloses the ctenidia as well as a pair of nephridia. Everyday Connection Can Snail Venom Be Used as a Pharmacological Painkiller? Marine snails of the genus Conus ( Figure 28.25 ) attack prey with a venomous sting. The toxin released, known as conotoxin, is a peptide with internal disulfide linkages. Conotoxins can bring about paralysis in humans, indicating that this toxin attacks neurological targets. Some conotoxins have been shown to block neuronal ion channels. These findings have led researchers to study conotoxins for possible medical applications. Conotoxins are an exciting area of potential pharmacological development, since these peptides may be possibly modified and used in specific medical conditions to inhibit the activity of specific neurons. For example, these toxins may be used to induce paralysis in muscles in specific health applications, similar to the use of botulinum toxin. Since the entire spectrum of conotoxins, as well as their mechanisms of action, are not completely known, the study of their potential applications is still in its infancy. Most research to date has focused on their use to treat neurological diseases. They have also shown some efficacy in relieving chronic pain, and the pain associated with conditions like sciatica and shingles. The study and use of biotoxins—toxins derived from living organisms—are an excellent example of the application of biological science to modern medicine. Class Cephalopoda (“head foot” animals), include octopi, squids, cuttlefish, and nautilus. Cephalopods are a class of shell-bearing animals as well as mollusks with a reduced shell. They display vivid coloration, typically seen in squids and octopi, which is used for camouflage. All animals in this class are carnivorous predators and have beak-like jaws at the anterior end. All cephalopods show the presence of a very well-developed nervous system along with eyes, as well as a closed circulatory system. The foot is lobed and developed into tentacles, and a funnel, which is used as their mode of locomotion. Suckers are present on the tentacles in octopi and squid. Ctenidia are enclosed in a large mantle cavity and are serviced by large blood vessels, each with its own heart associated with it; the mantle has siphonophores that facilitate exchange of water. Locomotion in cephalopods is facilitated by ejecting a stream of water for propulsion. This is called “jet” propulsion. A pair of nephridia is present within the mantle cavity. Sexual dimorphism is seen in this class of animals. Members of a species mate, and the female then lays the eggs in a secluded and protected niche. Females of some species care for the eggs for an extended period of time and may end up dying during that time period. Cephalopods such as squids and octopi also produce sepia or a dark ink, which is squirted upon a predator to assist in a quick getaway. Reproduction in cephalopods is different from other mollusks in that the egg hatches to produce a juvenile adult without undergoing the trochophore and veliger larval stages. In the shell-bearing Nautilus spp., the spiral shell is multi-chambered. These chambers are filled with gas or water to regulate buoyancy. The shell structure in squids and cuttlefish is reduced and is present internally in the form of a squid pen and cuttlefish bone, respectively. Examples are shown in Figure 28.26 . Members of class Scaphopoda (“boat feet”) are known colloquially as “tusk shells” or “tooth shells,” as evident when examining Dentalium , one of the few remaining scaphopod genera ( Figure 28.27 ). Scaphopods are usually buried in sand with the anterior opening exposed to water. These animals bear a single conical shell, which has both ends open. The head is rudimentary and protrudes out of the posterior end of the shell. These animals do not possess eyes, but they have a radula, as well as a foot modified into tentacles with a bulbous end, known as captaculae . Captaculae serve to catch and manipulate prey. Ctenidia are absent in these animals. Phylum Annelida Phylum Annelida includes segmented worms. These animals are found in marine, terrestrial, and freshwater habitats, but a presence of water or humidity is a critical factor for their survival, especially in terrestrial habitats. The name of the phylum is derived from the Latin word annellus , which means a small ring. Animals in this phylum show parasitic and commensal symbioses with other species in their habitat. Approximately 16,500 species have been described in phylum Annelida. The phylum includes earthworms, polychaete worms, and leeches. Annelids show protostomic development in embryonic stages and are often called “segmented worms” due to their key characteristic of metamerism , or true segmentation. Morphology Annelids display bilateral symmetry and are worm-like in overall morphology. Annelids have a segmented body plan wherein the internal and external morphological features are repeated in each body segment. Metamerism allows animals to become bigger by adding “compartments” while making their movement more efficient. This metamerism is thought to arise from identical teloblast cells in the embryonic stage, which give rise to identical mesodermal structures. The overall body can be divided into head, body, and pygidium (or tail). The clitellum is a reproductive structure that generates mucus that aids in sperm transfer and gives rise to a cocoon within which fertilization occurs; it appears as a fused band in the anterior third of the animal ( Figure 28.28 ). Anatomy The epidermis is protected by an acellular, external cuticle, but this is much thinner than the cuticle found in the ecdysozoans and does not require periodic shedding for growth. Circular as well as longitudinal muscles are located interior to the epidermis. Chitinous hairlike extensions, anchored in the epidermis and projecting from the cuticle, called setae/chaetae are present in every segment. Annelids show the presence of a true coelom, derived from embryonic mesoderm and protostomy. Hence, they are the most advanced worms. A well-developed and complete digestive system is present in earthworms (oligochaetes) with a mouth, muscular pharynx, esophagus, crop, and gizzard being present. The gizzard leads to the intestine and ends in an anal opening. A cross-sectional view of a body segment of an earthworm (a terrestrial type of annelid) is shown in Figure 28.29 ; each segment is limited by a membranous septum that divides the coelomic cavity into a series of compartments. Annelids possess a closed circulatory system of dorsal and ventral blood vessels that run parallel to the alimentary canal as well as capillaries that service individual tissues. In addition, these vessels are connected by transverse loops in every segment. These animals lack a well-developed respiratory system, and gas exchange occurs across the moist body surface. Excretion is facilitated by a pair of metanephridia (a type of primitive “kidney” that consists of a convoluted tubule and an open, ciliated funnel) that is present in every segment towards the ventral side. Annelids show well-developed nervous systems with a nerve ring of fused ganglia present around the pharynx. The nerve cord is ventral in position and bears enlarged nodes or ganglia in each segment. Annelids may be either monoecious with permanent gonads (as in earthworms and leeches) or dioecious with temporary or seasonal gonads that develop (as in polychaetes). However, cross-fertilization is preferred in hermaphroditic animals. These animals may also show simultaneous hermaphroditism and participate in simultaneous sperm exchange when they are aligned for copulation. Link to Learning This combination video and animation provides a close-up look at annelid anatomy. Classification of Phylum Annelida Phylum Annelida contains the class Polychaeta (the polychaetes) and the class Oligochaeta (the earthworms, leeches and their relatives). Earthworms are the most abundant members of the class Oligochaeta, distinguished by the presence of the clitellum as well as few, reduced chaetae (“oligo- = “few”; -chaetae = “hairs”). The number and size of chaetae are greatly diminished in Oligochaeta compared to the polychaetes ( poly =many, chaetae = hairs). The many chetae of polychaetes are also arranged within fleshy, flat, paired appendages that protrude from each segment called parapodia , which may be specialized for different functions in the polychates. The subclass Hirudinea includes leeches such as Hirudo medicinalis and Hemiclepsis marginata . The class Oligochaeta includes the subclass Hirudinia and the subclass Brachiobdella. A significant difference between leeches and other annelids is the development of suckers at the anterior and posterior ends and a lack of chaetae. Additionally, the segmentation of the body wall may not correspond to the internal segmentation of the coelomic cavity. This adaptation possibly helps the leeches to elongate when they ingest copious quantities of blood from host vertebrates. The subclass Brachiobdella includes species like Branchiobdella balcanica sketi and Branchiobdella astaci , worms that show similarity with leeches as well as oligochaetes. 28.4 Superphylum Ecdysozoa Learning Objectives By the end of this section, you will be able to: Describe the structural organization of nematodes Understand the importance of Caenorhabditis elegans in research Compare the internal systems and appendage specializations of phylum Arthropoda Discuss the environmental importance of arthropods Discuss the reasons for arthropod success and abundance Superphylum Ecdysozoa The superphylum Ecdysozoa contains an incredibly large number of species. This is because it contains two of the most diverse animal groups: phylum Nematoda (the roundworms) and Phylum Arthropoda (the arthropods). The most prominant distinguising feature of Ecdysozoans is their tough external covering called the cuticle. The cuticle provides a tough, but flexible exoskeleton tht protects these animals from water loss, predators and other aspects of the external environment. All members of this superphylum periodically molt, or shed their cuticle as they grow. After molting, they secrete a new cuticle that will last until their next growth phase. The process of molting and replacing the cuticle is called ecdysis, which is how the superphylum derived its name. Phylum Nematoda The Nematoda, like most other animal phyla, are triploblastic and possess an embryonic mesoderm that is sandwiched between the ectoderm and endoderm. They are also bilaterally symmetrical, meaning that a longitudinal section will divide them into right and left sides that are symmetrical. Furthermore, the nematodes, or roundworms, possess a pseudocoelom and consist of both free-living and parasitic forms. It has been said that were all the non-nematode matter of the biosphere removed, there would remain a shadow of the former world in the form of nematodes. 1 The arthropods, one of the most successful taxonomic groups on the planet, are coelomate organisms characterized by a hard exoskeleton and jointed appendages. Both the nematodes and arthropods belong to the superphylum Ecdysozoa that is believed to be a clade consisting of all evolutionary descendants from one common ancestor. The name derives from the word ecdysis, which refers to the shedding, or molting, of the exoskeleton. The phyla in this group have a hard cuticle that covers their bodies, which must be periodically shed and replaced for them to increase in size. 1 Stoll, N. R., “This wormy world. 1947,” Journal of Parasitology 85(3) (1999): 392-396. Phylum Nematoda includes more than 28,000 species with an estimated 16,000 being parasitic in nature. The name Nematoda is derived from the Greek word “Nemos,” which means “thread” and includes roundworms. Nematodes are present in all habitats with a large number of individuals of each species present in each. The free-living nematode, Caenorhabditis elegans has been extensively used as a model system in laboratories all over the world. Morphology In contrast with cnidarians, nematodes show a tubular morphology and circular cross-section. These animals are pseudocoelomates and show the presence of a complete digestive system with a distinct mouth and anus. This is in contrast with the cnidarians, where only one opening is present (an incomplete digestive system). The cuticle of Nematodes is rich in collagen and a carbohydrate-protein polymer called chitin, and forms an external “skeleton” outside the epidermis. The cuticle also lines many of the organs internally, including the pharynx and rectum. The epidermis can be either a single layer of cells or a syncytium, which is a multinucleated cell formed from the fusion of uninucleated cells. The overall morphology of these worms is cylindrical, as seen in Figure 28.31 . The head is radially symmetrical. A mouth opening is present at the anterior end with three or six lips as well as teeth in some species in the form of cuticle extensions. Some nematodes may present other external modifications like rings, head shields, or warts. Rings, however, do not reflect true internal body segmentation. The mouth leads to a muscular pharynx and intestine, which leads to a rectum and anal opening at the posterior end. The muscles of nematodes differ from those of most animals: They have a longitudinal layer only, which accounts for the whip-like motion of their movement. Excretory System In nematodes, specialized excretory systems are not well developed. Nitrogenous wastes may be lost by diffusion through the entire body or into the pseudocoelom (body cavity), where they are removed by specialized cells. Regulation of water and salt content of the body is achieved by renette glands, present under the pharynx in marine nematodes. Nervous system Most nematodes possess four longitudinal nerve cords that run along the length of the body in dorsal, ventral, and lateral positions. The ventral nerve cord is better developed than the dorsal or lateral cords. All nerve cords fuse at the anterior end, around the pharynx, to form head ganglia or the “brain” of the worm (which take the form of a ring around the pharynx) as well as at the posterior end to form the tail ganglia. In C . elegans , the nervous system accounts for nearly one-third of the total number of cells in the animal. Reproduction Nematodes employ a variety of reproductive strategies that range from monoecious to dioecious to parthenogenic, depending upon the species under consideration. C . elegans is a monoecious species and shows development of ova contained in a uterus as well as sperm contained in the spermatheca. The uterus has an external opening known as the vulva. The female genital pore is near the middle of the body, whereas the male’s is at the tip. Specialized structures at the tail of the male keep him in place while he deposits sperm with copulatory spicules. Fertilization is internal, and embryonic development starts very soon after fertilization. The embryo is released from the vulva during the gastrulation stage. The embryonic development stage lasts for 14 hours; development then continues through four successive larval stages with ecdysis between each stage—L1, L2, L3, and L4—ultimately leading to the development of a young male or female adult worm. Adverse environmental conditions like overcrowding and lack of food can result in the formation of an intermediate larval stage known as the dauer larva. Everyday Connection C. elegans : The Model System for Linking Developmental Studies with Genetics If biologists wanted to research how nicotine dependence develops in the body, how lipids are regulated, or observe the attractant or repellant properties of certain odors, they would clearly need to design three very different experiments. However, they might only need one object of study: C . elegans . The nematode Caenorhabditis elegans was brought into the focus of mainstream biological research by Dr. Sydney Brenner. Since 1963, Dr. Brenner and scientists worldwide have used this animal as a model system to study various physiological and developmental mechanisms. C . elegans is a free-living organism found in soil. It is easy to culture this organism on agar plates (10,000 worms/plate), it feeds on Escherichia coli (another long-term resident of biological laboratories worldwide), and therefore, it can be readily grown and maintained in a laboratory. The biggest asset of this nematode is its transparency, which helps researchers to observe and monitor changes within the animal with ease. It is also a simple organism with fewer than 1,000 cells and a genome of 20,000 genes. It shows chromosomal organization of DNA into five pairs of autosomes plus a pair of sex chromosomes, making it an ideal candidate to study genetics. Since every cell can be visualized and identified, this organism is useful for studying cellular phenomena like cell-cell interactions, cell-fate determinations, cell division, apoptosis, and intracellular transport. Another tremendous asset is the short life cycle of this worm ( Figure 28.32 ). It takes only 3 days to achieve the “egg to adult to daughter egg;” therefore, tracking genetic changes is easier in this animal. The total life span of C . elegans is 2 to 3 weeks; hence, age-related phenomena are easy to observe. Another feature that makes C . elegans an excellent experimental model system is that the position and number of the 959 cells present in adult hermaphrodites of this organism is constant. This feature is extremely significant when studying cell differentiation, cell-cell communication, and apoptosis. Lastly, C . elegans is also amenable to genetic manipulations using molecular methods, rounding off its usefulness as a model system. Biologists worldwide have created information banks and groups dedicated to research using C . elegans . Their findings have led, for example, to better understandings of cell communication during development, neuronal signaling and insight into lipid regulation (which is important in addressing health issues like the development of obesity and diabetes). In recent years, studies have enlightened the medical community with a better understanding of polycystic kidney disease. This simple organism has led biologists to complex and significant findings, growing the field of science in ways that touch the everyday world. A number of common parasitic nematodes serve as prime examples of parasitism. These animals exhibit complex lifecycles that involve multiple hosts, and they can have significant medical and veterinary impacts. Humans may become infected by Dracunculus medinensis , known as guinea worms, when they drink unfiltered water containing copepods ( Figure 28.33 ). Hookworms, such as Ancyclostoma and Necator , infest the intestines and feed on the blood of mammals, especially in dogs, cats, and humans. Trichina worms ( Trichinella ) are the causal organism of trichinosis in humans, often resulting from the consumption of undercooked pork; Trichinella can infect other mammalian hosts as well. Ascaris , a large intestinal roundworm, steals nutrition from its human host and may create physical blockage of the intestines. The filarial worms, such as Dirofilaria and Wuchereria , are commonly vectored by mosquitoes, which pass the infective agents among mammals through their blood-sucking activity. Dirofilaria immitis , a blood-infective parasite, is the notorious dog heartworm species. Wuchereria bancrofti infects the lymph nodes of humans, resulting in the non-lethal but deforming condition called elephantiasis, in which parts of the body become swelled to gigantic proportions due to obstruction of lymphatic drainage and inflammation of lymphatic tissues. Phylum Arthropoda The name “arthropoda” means “jointed legs” (in the Greek, “arthros” means “joint” and “podos” means “leg”); it aptly describes the enormous number of invertebrates included in this phylum. Arthropoda dominate the animal kingdom with an estimated 85 percent of known species included in this phylum and many arthropods yet undocumented. The principal characteristics of all the animals in this phylum are functional segmentation of the body and presence of jointed appendages. Arthropods also show the presence of an exoskeleton made principally of chitin, which is a waterproof, tough polysaccharide. Phylum Arthropoda is the largest phylum in the animal world, and insects form the single largest class within this phylum. Arthropods are eucoelomate, protostomic organisms. Phylum Arthropoda includes animals that have been successful in colonizing terrestrial, aquatic, and aerial habitats. This phylum is further classified into five subphyla: Trilobitomorpha (trilobites, all extinct), Hexapoda (insects and relatives), Myriapoda (millipedes, centipedes, and relatives), Crustaceans (crabs, lobsters, crayfish, isopods, barnacles, and some zooplankton), and Chelicerata (horseshoe crabs, arachnids, scorpions, and daddy longlegs). Trilobites are an extinct group of arthropods found chiefly in the pre-Cambrian Era that are probably most closely related to the Chelicerata. These are identified based on fossil records ( Figure 28.34 ). Morphology A unique feature of animals in the arthropod phylum is the presence of a segmented body and fusion of sets of segments that give rise to functional body regions called tagma. Tagma may be in the form of a head, thorax, and abdomen, or a cephalothorax and abdomen, or a head and trunk. A central cavity, called the hemocoel (or blood cavity), is present, and the open circulatory system is regulated by a tubular or single-chambered heart. Respiratory systems vary depending on the group of arthropod: insects and myriapods use a series of tubes (tracheae) that branch through the body, open to the outside through openings called spiracles, and perform gas exchange directly between the cells and air in the tracheae, whereas aquatic crustaceans utilize gills, terrestrial chelicerates employ book lungs, and aquatic chelicerates use book gills ( Figure 28.35 ). The book lungs of arachnids (scorpions, spiders, ticks and mites) contain a vertical stack of hemocoel wall tissue that somewhat resembles the pages of a book. Between each of the "pages" of tissue is an air space. This allows both sides of the tissue to be in contact with the air at all times, greatly increasing the efficiency of gas exchange. The gills of crustaceans are filamentous structures that exchange gases with the surrounding water. Groups of arthropods also differ in the organs used for excretion, with crustaceans possessing green glands and insects using Malpighian tubules, which work in conjunction with the hindgut to reabsorb water while ridding the body of nitrogenous waste. The cuticle is the covering of an arthropod. It is made up of two layers: the epicuticle, which is a thin, waxy water-resistant outer layer containing no chitin, and the layer beneath it, the chitinous procuticle. Chitin is a tough, flexible polysaccharide. In order to grow, the arthropod must shed the exoskeleton during a process called ecdysis (“to strip off”); this is a cumbersome method of growth, and during this time, the animal is vulnerable to predation. The characteristic morphology of representative animals from each subphylum is described below. Subphylum Hexapoda The name Hexapoda denotes the presence of six legs (three pairs) in these animals as differentiated from the number of pairs present in other arthropods. Hexapods are characterized by the presence of a head, thorax, and abdomen, constituting three tagma. The thorax bears the wings as well as six legs in three pairs. Many of the common insects we encounter on a daily basis—including ants, cockroaches, butterflies, and flies—are examples of Hexapoda. Amongst the hexapods, the insects ( Figure 28.36 ) are the largest class in terms of species diversity as well as biomass in terrestrial habitats. Typically, the head bears one pair of sensory antennae, mandibles as mouthparts, a pair of compound eyes, and some ocelli (simple eyes) along with numerous sensory hairs. The thorax bears three pairs of legs (one pair per segment) and two pairs of wings, with one pair each on the second and third thoracic segments. The abdomen usually has eleven segments and bears reproductive apertures. Hexapoda includes insects that are winged (like fruit flies) and wingless (like fleas). Visual Connection Which of the following statements about insects is false? Insects have both dorsal and ventral blood vessels. Insects have spiracles, openings that allow air to enter. The trachea is part of the digestive system. Insects have a developed digestive system with a mouth, crop, and intestine. Subphylum Myriapoda Subphylum Myriapoda includes arthropods with numerous legs. Although the name is hyperbolic in suggesting that myriad legs are present in these invertebrates, the number of legs may vary from 10 to 750. This subphylum includes 13,000 species; the most commonly found examples are millipedes and centipedes. All myriapods are terrestrial animals and prefer a humid environment. Myriapods are typically found in moist soils, decaying biological material, and leaf litter. Subphylum Myriapoda is divided into four classes: Chilopoda, Symphyla, Diplopoda, and Pauropoda. Centipedes like Scutigera coleoptrata ( Figure 28.37 ) are classified as chilopods. These animals bear one pair of legs per segment, mandibles as mouthparts, and are somewhat dorsoventrally flattened. The legs in the first segment are modified to form forcipules (poison claws) that deliver poison to prey like spiders and cockroaches, as these animals are all predatory. Millipedes bear two pairs of legs per diplosegment, a feature that results from embryonic fusion of adjacent pairs of body segments, are usually rounder in cross-section, and are herbivores or detritivores. Millipedes have visibly more numbers of legs as compared to centipedes, although they do not bear a thousand legs ( Figure 28.38 ). Subphylum Crustacea Crustaceans are the most dominant aquatic arthropods, since the total number of marine crustacean species stands at 67,000, but there are also freshwater and terrestrial crustacean species. Krill, shrimp, lobsters, crabs, and crayfish are examples of crustaceans ( Figure 28.38 ). Terrestrial species like the wood lice ( Armadillidium spp.) (also called pill bugs, rolly pollies, potato bugs, or isopods) are also crustaceans, although the number of non-aquatic species in this subphylum is relatively low. Crustaceans possess two pairs of antennae, mandibles as mouthparts, and biramous (“two branched”) appendages, which means that their legs are formed in two parts, as distinct from the uniramous (“one branched”) myriapods and hexapods ( Figure 28.39 ). Unlike that of the Hexapoda, the head and thorax of most crustaceans is fused to form a cephalothorax ( Figure 28.40 ), which is covered by a plate called the carapace, thus producing a body structure of two tagma. Crustaceans have a chitinous exoskeleton that is shed by molting whenever the animal increases in size. The exoskeletons of many species are also infused with calcium carbonate, which makes them even stronger than in other arthropods. Crustaceans have an open circulatory system where blood is pumped into the hemocoel by the dorsally located heart. Hemocyanin and hemoglobin are the respiratory pigments present in these animals. Most crustaceans are dioecious, which means that the sexes are separate. Some species like barnacles may be hermaphrodites . Serial hermaphroditism, where the gonad can switch from producing sperm to ova, may also be seen in some species. Fertilized eggs may be held within the female of the species or may be released in the water. Terrestrial crustaceans seek out damp spaces in their habitats to lay eggs. Larval stages— nauplius and zoea —are seen in the early development of crustaceans. A cypris larva is also seen in the early development of barnacles ( Figure 28.41 ). Crustaceans possess a tripartite brain and two compound eyes. Most crustaceans are carnivorous, but herbivorous and detritivorous species are also known. Crustaceans may also be cannibalistic when extremely high populations of these organisms are present. Subphylum Chelicerata This subphylum includes animals such as spiders, scorpions, horseshoe crabs, and sea spiders. This subphylum is predominantly terrestrial, although some marine species also exist. An estimated 77,000 species are included in subphylum Chelicerata. Chelicerates are found in almost all habitats. The body of chelicerates may be divided into two parts: prosoma and opisthosoma, which are basically the equivalents of cephalothorax (usually smaller) and abdomen (usually larger). A “head” tagmum is not usually discernible. The phylum derives its name from the first pair of appendages: the chelicerae ( Figure 28.42 ), which are specialized, claw-like or fang-like mouthparts. These animals do not possess antennae. The second pair of appendages is known as pedipalps . In some species, like sea spiders, an additional pair of appendages, called ovigers , is present between the chelicerae and pedipalps. Chelicerae are mostly used for feeding, but in spiders, these are often modified into fangs that inject venom into their prey before feeding ( Figure 28.43 ). Members of this subphylum have an open circulatory system with a heart that pumps blood into the hemocoel. Aquatic species have gills, whereas terrestrial species have either trachea or book lungs for gaseous exchange. Most chelicerates ingest food using a preoral cavity formed by the chelicerae and pedipalps. Some chelicerates may secrete digestive enzymes to pre-digest food before ingesting it. Parasitic chelicerates like ticks and mites have evolved blood-sucking apparatuses. The nervous system in chelicerates consists of a brain and two ventral nerve cords. These animals use external fertilization as well as internal fertilization strategies for reproduction, depending upon the species and its habitat. Parental care for the young ranges from absolutely none to relatively prolonged care. Link to Learning Visit this site to click through a lesson on arthropods, including interactive habitat maps, and more. 28.5 Superphylum Deuterostomia Learning Objectives By the end of this section, you will be able to: Describe the distinguishing characteristics of echinoderms Describe the distinguishing characteristics of chordates The phyla Echinodermata and Chordata (the phylum in which humans are placed) both belong to the superphylum Deuterostomia. Recall that protostome and deuterostomes differ in certain aspects of their embryonic development, and they are named based on which opening of the digestive cavity develops first. The word deuterostome comes from the Greek word meaning “mouth second,” indicating that the anus is the first to develop. There are a series of other developmental characteristics that differ between protostomes and deuterostomes, including the mode of formation of the coelom and the early cell division of the embryo. In deuterostomes, internal pockets of the endodermal lining called the archenteron fuse to form the coelom. The endodermal lining of the archenteron (or the primitive gut) forms membrane protrusions that bud off and become the mesodermal layer. These buds, known as coelomic pouches, fuse to form the coelomic cavity, as they eventually separate from the endodermal layer. The resultant coelom is termed an enterocoelom . The archenteron develops into the alimentary canal, and a mouth opening is formed by invagination of ectoderm at the pole opposite the blastopore of the gastrula. The blastopore forms the anus of the alimentary system in the juvenile and adult forms. The fates of embryonic cells in deuterostomes can be altered if they are experimentally moved to a different location in the embryo due to indeterminant cleavage in early embryogenesis. Phylum Echinodermata Echinodermata are so named owing to their spiny skin (from the Greek “echinos” meaning “spiny” and “dermos” meaning “skin”), and this phylum is a collection of about 7,000 described living species. Echinodermata are exclusively marine organisms. Sea stars ( Figure 28.44 ), sea cucumbers, sea urchins, sand dollars, and brittle stars are all examples of echinoderms. To date, no freshwater or terrestrial echinoderms are known. Morphology and Anatomy Adult echinoderms exhibit pentaradial symmetry and have a calcareous endoskeleton made of ossicles, although the early larval stages of all echinoderms have bilateral symmetry. The endoskeleton is developed by epidermal cells and may possess pigment cells, giving vivid colors to these animals, as well as cells laden with toxins. Gonads are present in each arm. In echinoderms like sea stars, every arm bears two rows of tube feet on the oral side. These tube feet help in attachment to the substratum. These animals possess a true coelom that is modified into a unique circulatory system called a water vascular system . An interesting feature of these animals is their power to regenerate, even when over 75 percent of their body mass is lost. Water Vascular System Echinoderms possess a unique ambulacral or water vascular system, consisting of a central ring canal and radial canals that extend along each arm. Water circulates through these structures and facilitates gaseous exchange as well as nutrition, predation, and locomotion. The water vascular system also projects from holes in the skeleton in the form of tube feet. These tube feet can expand or contract based on the volume of water present in the system of that arm. By using hydrostatic pressure, the animal can either protrude or retract the tube feet. Water enters the madreporite on the aboral side of the echinoderm. From there, it passes into the stone canal, which moves water into the ring canal. The ring canal connects the radial canals (there are five in a pentaradial animal), and the radial canals move water into the ampullae, which have tube feet through which the water moves. By moving water through the unique water vascular system, the echinoderm can move and force open mollusk shells during feeding. Nervous System The nervous system in these animals is a relatively simple structure with a nerve ring at the center and five radial nerves extending outward along the arms. Structures analogous to a brain or derived from fusion of ganglia are not present in these animals. Excretory System Podocytes, cells specialized for ultrafiltration of bodily fluids, are present near the center of echinoderms. These podocytes are connected by an internal system of canals to an opening called the madreporite . Reproduction Echinoderms are sexually dimorphic and release their eggs and sperm cells into water; fertilization is external. In some species, the larvae divide asexually and multiply before they reach sexual maturity. Echinoderms may also reproduce asexually, as well as regenerate body parts lost in trauma. Classes of Echinoderms This phylum is divided into five extant classes: Asteroidea (sea stars), Ophiuroidea (brittle stars), Echinoidea (sea urchins and sand dollars), Crinoidea (sea lilies or feather stars), and Holothuroidea (sea cucumbers) ( Figure 28.45 ). The most well-known echinoderms are members of class Asteroidea, or sea stars. They come in a large variety of shapes, colors, and sizes, with more than 1,800 species known so far. The key characteristic of sea stars that distinguishes them from other echinoderm classes includes thick arms (ambulacra) that extend from a central disk where organs penetrate into the arms. Sea stars use their tube feet not only for gripping surfaces but also for grasping prey. Sea stars have two stomachs, one of which can protrude through their mouths and secrete digestive juices into or onto prey, even before ingestion. This process can essentially liquefy the prey and make digestion easier. Link to Learning Explore the sea star’s body plan up close, watch one move across the sea floor, and see it devour a mussel. Brittle stars belong to the class Ophiuroidea. Unlike sea stars, which have plump arms, brittle stars have long, thin arms that are sharply demarcated from the central disk. Brittle stars move by lashing out their arms or wrapping them around objects and pulling themselves forward. Sea urchins and sand dollars are examples of Echinoidea. These echinoderms do not have arms, but are hemispherical or flattened with five rows of tube feet that help them in slow movement; tube feet are extruded through pores of a continuous internal shell called a test. Sea lilies and feather stars are examples of Crinoidea. Both of these species are suspension feeders. Sea cucumbers of class Holothuroidea are extended in the oral-aboral axis and have five rows of tube feet. These are the only echinoderms that demonstrate “functional” bilateral symmetry as adults, because the uniquely extended oral-aboral axis compels the animal to lie horizontally rather than stand vertically. Phylum Chordata Animals in the phylum Chordata share four key features that appear at some stage of their development: a notochord, a dorsal hollow nerve cord, pharyngeal slits, and a post-anal tail. In some groups, some of these traits are present only during embryonic development. In addition to containing vertebrate classes, the phylum Chordata contains two clades of invertebrates: Urochordata (tunicates) and Cephalochordata (lancelets). Most tunicates live on the ocean floor and are suspension feeders. Lancelets are suspension feeders that feed on phytoplankton and other microorganisms.
introduction_to_sociology
Learning Objectives 3.1 What Is Culture? Differentiate between culture and society Explain material versus nonmaterial culture Discuss the concept of cultural universalism as it relates to society Compare and contrast ethnocentrism and xenocentrism 3.2 Elements of Culture Understand how values and beliefs differ from norms Explain the significance of symbols and language to a culture Explain the Sapir-Whorf hypothesis Discuss the role of social control within culture 3.3 Pop Culture, Subculture, and Cultural Change Discuss the roles of both high culture and pop culture within society Differentiate between subculture and counterculture Explain the role of innovation, invention, and discovery in culture Understand the role of cultural lag and globalization in cultural change 3.4 Theoretical Perspectives on Culture Discuss the major theoretical approaches to cultural interpretation Introduction to Culture Are there rules for eating at McDonald’s? Generally, we do not think about rules in a fast food restaurant, but if you look around one on a typical weekday, you will see people acting as if they were trained for the role of fast food customer. They stand in line, pick items from the colorful menus, swipe debit cards to pay, and wait to collect trays of food. After a quick meal, customers wad up their paper wrappers and toss them into garbage cans. Customers’ movement through this fast food routine is orderly and predictable, even if no rules are posted and no officials direct the process. If you want more insight into these unwritten rules, think about what would happen if you behaved according to some other standards. (You would be doing what sociologists call ethnomethodology: deliberately disrupting social norms in order to learn about them.) For example, call ahead for reservations, ask the cashier detailed questions about the food’s ingredients or how it is prepared. Ask to have your meal served to you at your table. Or throw your trash on the ground as you leave. Chances are, you will elicit hostile responses from the restaurant employees and your fellow customers. People have written entire books analyzing the significance of fast food customs. They examine the extensive, detailed physicality of fast food: the food itself, wrappers, bags, trays, those tiny ketchup packets, the tables and chairs, and even the restaurant building. Everything about a chain restaurant reflects culture , the beliefs and behaviors that a social group shares. Sociological analysis can be applied to every expression of culture, from sporting events to holidays, from education to transportation, from fashion to etiquette. In everyday conversation, people rarely distinguish between the terms culture and society, but the terms have slightly different meanings, and the distinction is important to a sociologist. A society describes a group of people who share a community and a culture. By “community,” sociologists refer to a definable region—as small as a neighborhood (Brooklyn, or “the east side of town”), as large as a country (Ethiopia, the United States, or Nepal), or somewhere in between (in America, this might include someone who identifies with Southern or Midwestern society). To clarify, a culture represents the beliefs and practices of a group, while society represents the people who share those beliefs and practices. Neither society nor culture could exist without the other. In this chapter, we examine the relationship between culture and society in greater detail, paying special attention to the elements and forces that shape culture, including diversity and cultural changes. A final discussion touches on the different theoretical perspectives from which sociologists research culture.
[ { "answer": { "ans_choice": 1, "ans_text": "culture and society" }, "bloom": "1", "hl_context": "<hl> In everyday conversation , people rarely distinguish between the terms culture and society , but the terms have slightly different meanings , and the distinction is important to a sociologist . <hl> A society describes a group of people who share a community and a culture . By “ community , ” sociologists refer to a definable region — as small as a neighborhood ( Brooklyn , or “ the east side of town ” ) , as large as a country ( Ethiopia , the United States , or Nepal ) , or somewhere in between ( in America , this might include someone who identifies with Southern or Midwestern society ) . To clarify , a culture represents the beliefs and practices of a group , while society represents the people who share those beliefs and practices . Neither society nor culture could exist without the other . In this chapter , we examine the relationship between culture and society in greater detail , paying special attention to the elements and forces that shape culture , including diversity and cultural changes . A final discussion touches on the different theoretical perspectives from which sociologists research culture . <hl> Differentiate between culture and society <hl>", "hl_sentences": "In everyday conversation , people rarely distinguish between the terms culture and society , but the terms have slightly different meanings , and the distinction is important to a sociologist . Differentiate between culture and society", "question": { "cloze_format": "The terms _________________ and ______________ are often used interchangeably, but have nuances that differentiate them.", "normal_format": "What are the two terms often used interchangeably but have nuances that differentiate them? ", "question_choices": [ "imperialism and relativism", "culture and society", "society and ethnocentrism", "ethnocentrism and xenocentrism" ], "question_id": "fs-id1778792", "question_text": "The terms _________________ and ______________ are often used interchangeably, but have nuances that differentiate them." }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 2, "ans_text": "xenocentrism" }, "bloom": null, "hl_context": "<hl> is the opposite of ethnocentrism , and refers to the belief that another culture is superior to one ’ s own . <hl> ( The Greek root word xeno , pronounced “ ZEE-no , ” means “ stranger ” or “ foreign guest . ” ) An exchange student who goes home after a semester abroad or a sociologist who returns from the field may find it difficult to associate with the values of their own culture after having experienced what they deem a more upright or nobler way of living . <hl> Xenocentrism <hl> <hl> cultural imperialism , the deliberate imposition of one ’ s own cultural values on another culture . <hl> Europe ’ s colonial expansion , begun in the 16th century , was often accompanied by a severe cultural imperialism . European colonizers often viewed the people in the lands they colonized as uncultured savages who were in need of European governance , dress , religion , and other cultural practices . A more modern example of cultural imperialism may include the work of international aid agencies who introduce agricultural methods and plant species from developed countries while overlooking indigenous varieties and agricultural approaches that are better suited to the particular region . Ethnocentrism can be so strong that when confronted with all the differences of a new culture , one may experience disorientation and frustration . In sociology , we call this <hl> ethnocentrism , or evaluating and judging another culture based on how it compares to one ’ s own cultural norms . <hl> Ethnocentrism , as sociologist William Graham Sumner ( 1906 ) described the term , involves a belief or attitude that one ’ s own culture is better than all others . Almost everyone is a little bit ethnocentric . For example , Americans tend to say that people from England drive on the “ wrong ” side of the road , rather than the “ other ” side . Someone from a country where dog meat is standard fare might find it off-putting to see a dog in a French restaurant — not on the menu , but as a pet and patron ’ s companion . A high level of appreciation for one ’ s own culture can be healthy ; a shared sense of community pride , for example , connects people in a society . But ethnocentrism can lead to disdain or dislike for other cultures , causing misunderstanding and conflict . People with the best intentions sometimes travel to a society to “ help ” its people , seeing them as uneducated or backward ; essentially inferior . In reality , these travelers are guilty of", "hl_sentences": "is the opposite of ethnocentrism , and refers to the belief that another culture is superior to one ’ s own . Xenocentrism cultural imperialism , the deliberate imposition of one ’ s own cultural values on another culture . ethnocentrism , or evaluating and judging another culture based on how it compares to one ’ s own cultural norms .", "question": { "cloze_format": "The belief that one's culture is inferior to another culture is called ____.", "normal_format": "What is called the belief that one’s culture is inferior to another culture?", "question_choices": [ "ethnocentrism", "nationalism", "xenocentrism", "imperialism" ], "question_id": "fs-id1440126", "question_text": "The belief that one’s culture is inferior to another culture is called:" }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 3, "ans_text": "universalism" }, "bloom": "4", "hl_context": "Researchers also found that music can foster a sense of wholeness within a group . In fact , scientists who study the evolution of language have concluded that originally language ( an established component of group identity ) and music were one ( Darwin 1871 ) . Additionally , since music is largely nonverbal , the sounds of music can cross societal boundaries more easily than words . Music allows people to make connections where language might be a more difficult barricade . <hl> As Fritz and his team found , music and the emotions it conveys can be cultural universals . <hl> Music has the ability to evoke emotional responses . <hl> In television shows , movies , even commercials , music elicits laughter , sadness , or fear . <hl> <hl> Are these types of musical cues cultural universals ? <hl>", "hl_sentences": "As Fritz and his team found , music and the emotions it conveys can be cultural universals . In television shows , movies , even commercials , music elicits laughter , sadness , or fear . Are these types of musical cues cultural universals ?", "question": { "cloze_format": "Most cultures have been found to identify laughter as a sign of humor, joy, or pleasure. Likewise, most cultures recognize music in some form. Music and laughter are examples of ___ .", "normal_format": "Most cultures have been found to identify laughter as a sign of humor, joy, or pleasure. Likewise, most cultures recognize music in some form. What are music and laughter are examples of?", "question_choices": [ "relativism", "ethnocentrism", "xenocentrism", "universalism" ], "question_id": "fs-id1314616", "question_text": "Most cultures have been found to identify laughter as a sign of humor, joy, or pleasure. Likewise, most cultures recognize music in some form. Music and laughter are examples of:" }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 0, "ans_text": "A symbol" }, "bloom": null, "hl_context": "Humans , consciously and subconsciously , are always striving to make sense of their surrounding world . <hl> Symbols — such as gestures , signs , objects , signals , and words — help people understand the world . <hl> <hl> Symbols provide clues to understanding experiences . <hl> <hl> They convey recognizable meanings that are shared by societies . <hl>", "hl_sentences": "Symbols — such as gestures , signs , objects , signals , and words — help people understand the world . Symbols provide clues to understanding experiences . They convey recognizable meanings that are shared by societies .", "question": { "cloze_format": "A nation's flag is ____.", "normal_format": "What is a nation’s flag?", "question_choices": [ "A symbol", "A value", "A culture", "A folkway" ], "question_id": "fs-id1165528304715", "question_text": "A nation’s flag is:" }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 2, "ans_text": "social control" }, "bloom": null, "hl_context": "One way societies strive to put values into action is through rewards , sanctions , and punishments . When people observe the norms of society and uphold its values , they are often rewarded . A boy who helps an elderly woman board a bus may receive a smile and a “ thank you . ” A business manager who raises profit margins may receive a quarterly bonus . <hl> People sanction certain behaviors by giving their support , approval , or permission , or by instilling formal actions of disapproval and non-support . <hl> <hl> Sanctions are a form of social control , a way to encourage conformity to cultural norms . <hl> Sometimes people conform to norms in anticipation or expectation of positive sanctions : good grades , for instance , may mean praise from parents and teachers .", "hl_sentences": "People sanction certain behaviors by giving their support , approval , or permission , or by instilling formal actions of disapproval and non-support . Sanctions are a form of social control , a way to encourage conformity to cultural norms .", "question": { "cloze_format": "The existence of social norms, both formal and informal, is one of the main things that inform ___________, otherwise known as a way to encourage social conformity.", "normal_format": "The existence of social norms, both formal and informal, is one of the main things that inform which of the following, otherwise known as a way to encourage social conformity?", "question_choices": [ "values", "sanctions", "social control", "mores" ], "question_id": "fs-id1165528356832", "question_text": "The existence of social norms, both formal and informal, is one of the main things that inform ___________, otherwise known as a way to encourage social conformity." }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 0, "ans_text": "mores are primarily linked to morality, whereas folkways are primarily linked to being commonplace within a culture" }, "bloom": "3", "hl_context": "Unlike mores , folkways are norms without any moral underpinnings . <hl> Rather , folkways direct appropriate behavior in the day-to-day practices and expressions of a culture . <hl> Folkways indicate whether to shake hands or kiss on the cheek when greeting another person . They specify whether to wear a tie and blazer or a T-shirt and sandals to an event . In Canada , women can smile and say hello to men on the street . In Egypt , it ’ s not acceptable . In regions in the southern United States , bumping into an acquaintance means stopping to chat . It ’ s considered rude not to , no matter how busy one is . In other regions , people guard their privacy and value time efficiency . A simple nod of the head is enough . Norms may be further classified as either mores or folkways . <hl> Mores ( mor-ays ) are norms that embody the moral views and principles of a group . <hl> <hl> Violating them can have serious consequences . <hl> The strongest mores are legally protected with laws or other formal norms . In the United States , for instance , murder is considered immoral , and it ’ s punishable by law ( a formal norm ) . But more often , mores are judged and guarded by public sentiment ( an informal norm ) . People who violate mores are seen as shameful . They can even be shunned or banned from some groups . The mores of the U . S . school system require that a student ’ s writing be in the student ’ s own words or use special forms ( such as quotation marks and a whole system of citation ) for crediting other writers . Writing another person ’ s words as if they are one ’ s own has a name — plagiarism . The consequences for violating this norm are severe , and can usually result in expulsion .", "hl_sentences": "Rather , folkways direct appropriate behavior in the day-to-day practices and expressions of a culture . Mores ( mor-ays ) are norms that embody the moral views and principles of a group . Violating them can have serious consequences .", "question": { "cloze_format": "The biggest difference between mores and folkways is that ____.", "normal_format": "What is the biggest difference between mores and folkways?", "question_choices": [ "mores are primarily linked to morality, whereas folkways are primarily linked to being commonplace within a culture", "mores are absolute, whereas folkways are temporary", "mores refer to material culture, whereas folkways refer to nonmaterial culture", "mores refer to nonmaterial culture, whereas folkways refer to material culture" ], "question_id": "fs-id1165528386507", "question_text": "The biggest difference between mores and folkways is that" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 1, "ans_text": "Sapir-Whorf" }, "bloom": null, "hl_context": "<hl> The Sapir-Whorf hypothesis is based on the idea that people experience their world through their language , and that they therefore understand their world through the culture embedded in their language . <hl> The hypothesis , which has also been called linguistic relativity , states that language shapes thought ( Swoyer 2003 ) . Studies have shown , for instance , that unless people have access to the word “ ambivalent , ” they don ’ t recognize an experience of uncertainty due to conflicting positive and negative feelings about one issue . Essentially , the hypothesis argues , if a person can ’ t describe the experience , the person is not having the experience .", "hl_sentences": "The Sapir-Whorf hypothesis is based on the idea that people experience their world through their language , and that they therefore understand their world through the culture embedded in their language .", "question": { "cloze_format": "The notion that people cannot feel or experience somthing that they do not have a word for can be explained by ____.", "normal_format": "What can be explained by the notion that people cannot feel or experience something for which they do not have a word?", "question_choices": [ "linguistics", "Sapir-Whorf", "Ethnographic imagery", "bilingualism" ], "question_id": "fs-id1165528386486", "question_text": "The notion that people cannot feel or experience something that they do not have a word for can be explained by:" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 2, "ans_text": "Regulates behavior" }, "bloom": "1", "hl_context": "One way societies strive to put values into action is through rewards , sanctions , and punishments . When people observe the norms of society and uphold its values , they are often rewarded . A boy who helps an elderly woman board a bus may receive a smile and a “ thank you . ” A business manager who raises profit margins may receive a quarterly bonus . <hl> People sanction certain behaviors by giving their support , approval , or permission , or by instilling formal actions of disapproval and non-support . <hl> <hl> Sanctions are a form of social control , a way to encourage conformity to cultural norms . <hl> Sometimes people conform to norms in anticipation or expectation of positive sanctions : good grades , for instance , may mean praise from parents and teachers .", "hl_sentences": "People sanction certain behaviors by giving their support , approval , or permission , or by instilling formal actions of disapproval and non-support . Sanctions are a form of social control , a way to encourage conformity to cultural norms .", "question": { "cloze_format": "Cultural sanctions can also be viewed as ways that society ____.", "normal_format": "Cultural sanctions can be viewed as ways that society do what?", "question_choices": [ "Establishes leaders", "Determines language", "Regulates behavior", "Determines laws" ], "question_id": "fs-id1165528306935", "question_text": "Cultural sanctions can also be viewed as ways that society:" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 0, "ans_text": "Dostoevsky style in film; “American Idol” winners" }, "bloom": "3", "hl_context": "The term popular culture refers to the pattern of cultural experiences and attitudes that exist in mainstream society . Popular culture events might include a parade , a baseball game , or the season finale of a TV show . Rock and pop music — “ pop ” short for “ popular ” — are part of popular culture . In modern times , popular culture is often expressed and spread via commercial media such as radio , television , movies , the music industry , publishers , and corporate-run websites . Unlike high culture , popular culture is known and accessible to most people . <hl> You can share a discussion of favorite football teams with a new coworker , or comment on “ American Idol ” when making small talk in line at the grocery store . <hl> <hl> But if you tried to launch into a deep discussion on the classical Greek play Antigone , few members of American society today would be familiar with it . <hl>", "hl_sentences": "You can share a discussion of favorite football teams with a new coworker , or comment on “ American Idol ” when making small talk in line at the grocery store . But if you tried to launch into a deep discussion on the classical Greek play Antigone , few members of American society today would be familiar with it .", "question": { "cloze_format": "An example of high culture is ___________, whereas an example of popular culture would be ____________.", "normal_format": "What is an example of high culture, whereas what would be an example of popular culture?", "question_choices": [ "Dostoevsky style in film; “American Idol” winners", "medical marijuana; film noir", "country music; pop music", "political theory; sociological theory" ], "question_id": "fs-id1798327", "question_text": "An example of high culture is ___________, whereas an example of popular culture would be ____________." }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 0, "ans_text": "Counterculture" }, "bloom": "1", "hl_context": "<hl> Sociologists distinguish subcultures from countercultures , which are a type of subculture that rejects some of the larger culture ’ s norms and values . <hl> <hl> In contrast to subcultures , which operate relatively smoothly within the larger society , countercultures might actively defy larger society by developing their own set of rules and norms to live by , sometimes even creating communities that operate outside of greater society . <hl>", "hl_sentences": "Sociologists distinguish subcultures from countercultures , which are a type of subculture that rejects some of the larger culture ’ s norms and values . In contrast to subcultures , which operate relatively smoothly within the larger society , countercultures might actively defy larger society by developing their own set of rules and norms to live by , sometimes even creating communities that operate outside of greater society .", "question": { "cloze_format": "The Ku Klux Klan is an example of ____.", "normal_format": "The Ku Klux Klan is an example of what part of culture?", "question_choices": [ "Counterculture", "Subculture", "Multiculturalism", "Afrocentricity" ], "question_id": "fs-id1738528", "question_text": "The Ku Klux Klan is an example of what part of culture?" }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 2, "ans_text": "subculture" }, "bloom": "1", "hl_context": "Skinny jeans , chunky glasses , and T-shirts with vintage logos — the American hipster is a recognizable figure in the modern United States . Based predominately in metropolitan areas , sometimes clustered around hotspots such as the Williamsburg neighborhood in New York City , hipsters define themselves through a rejection of the mainstream . <hl> As a subculture , hipsters spurn many of the values and beliefs of American culture , preferring vintage clothing to fashion and a bohemian lifestyle to one of wealth and power . <hl> While hipster culture may seem to be the new trend among young , middle-class youth , the history of the group stretches back to the early decades of the 1900s . <hl> The Evolution of American Hipster Subculture <hl>", "hl_sentences": "As a subculture , hipsters spurn many of the values and beliefs of American culture , preferring vintage clothing to fashion and a bohemian lifestyle to one of wealth and power . The Evolution of American Hipster Subculture", "question": { "cloze_format": "Modern-day hipsters are an example of ___ .", "normal_format": "What are modern-day hipsters an example of?", "question_choices": [ "ethnocentricity", "counterculture", "subculture", "high culture" ], "question_id": "fs-id1306864", "question_text": "Modern-day hipsters are an example of:" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 1, "ans_text": "Discovery involves finding something that already exists, but invention puts things together in a new way" }, "bloom": "3", "hl_context": "<hl> Inventions result when something new is formed from existing objects or concepts — when things are put together in an entirely new manner . <hl> In the late 1800s and early 1900s , electric appliances were invented at an astonishing pace . Cars , airplanes , vacuum cleaners , lamps , radios , telephones , and televisions were all new inventions . Inventions may shape a culture when people use them in place of older ways of carrying out activities and relating to others , or as a way to carry out new kinds of activities . Their adoption reflects ( and may shape ) cultural values , and their use may require new norms for new situations . An innovation refers to an object or concept ’ s initial appearance in society — it ’ s innovative because it is markedly new . There are two ways to come across an innovative object or idea : discover it or invent it . <hl> Discoveries make known previously unknown but existing aspects of reality . <hl> In 1610 , when Galileo looked through his telescope and discovered Saturn , the planet was already there , but until then , no one had known about it . When Christopher Columbus encountered America , the land was , of course , already well known to its inhabitants . However , Columbus ’ s discovery was new knowledge for Europeans , and it opened the way to changes in European culture , as well as to the cultures of the discovered lands . For example , new foods such as potatoes and tomatoes transformed the European diet , and horses brought from Europe changed hunting practices of Native American tribes of the Great Plains .", "hl_sentences": "Inventions result when something new is formed from existing objects or concepts — when things are put together in an entirely new manner . Discoveries make known previously unknown but existing aspects of reality .", "question": { "cloze_format": "The major difference between invention and discovery is that ___ .", "normal_format": "What is the major difference between invention and discovery?", "question_choices": [ "Invention is based on technology, whereas discovery is usually based on culture", "Discovery involves finding something that already exists, but invention puts things together in a new way", "Invention refers to material culture, whereas discovery can be material or theoretic, like laws of physics", "Invention is typically used to refer to international objects, whereas discovery refers to that which is local to one’s culture" ], "question_id": "fs-id1805964", "question_text": "The major difference between invention and discovery is:" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 1, "ans_text": "diffusion" }, "bloom": "2", "hl_context": "<hl> Alongside the process of globalization is diffusion , or , the spread of material and nonmaterial culture . <hl> <hl> While globalization refers to the integration of markets , diffusion relates a similar process to the integration of international cultures . <hl> <hl> Middle-class Americans can fly overseas and return with a new appreciation of Thai noodles or Italian gelato . <hl> Access to television and the Internet has brought the lifestyles and values portrayed in American sitcoms into homes around the globe . Twitter feeds from public demonstrations in one nation have encouraged political protesters in other countries . When this kind of diffusion occurs , material objects and ideas from one culture are introduced into another . 3.4 Theoretical Perspectives on Culture", "hl_sentences": "Alongside the process of globalization is diffusion , or , the spread of material and nonmaterial culture . While globalization refers to the integration of markets , diffusion relates a similar process to the integration of international cultures . Middle-class Americans can fly overseas and return with a new appreciation of Thai noodles or Italian gelato .", "question": { "cloze_format": "That McDonald’s is found in almost every country around the world is an example of ___.", "normal_format": "What is an example of that McDonald’s is found in almost every country around the world?", "question_choices": [ "globalization", "diffusion", "culture lag", "xenocentrism" ], "question_id": "fs-id1555851", "question_text": "That McDonald’s is found in almost every country around the world is an example of:" }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 2, "ans_text": "Conflict theory" }, "bloom": "4", "hl_context": "<hl> At the core of conflict theory is the effect of economic production and materialism : dependence on technology in rich nations versus a lack of technology and education in poor nations . <hl> Conflict theorists believe that a society ’ s system of material production has an effect on the rest of culture . <hl> People who have less power also have less ability to adapt to cultural change . <hl> This view contrasts with the perspective of functionalism . <hl> In the US culture of capitalism , to illustrate , we continue to strive toward the promise of the American dream , which perpetuates the belief that the wealthy deserve their privileges . <hl> Symbolic interactionism is a sociological perspective that is most concerned with the face-to-face interactions between members of society . Interactionists see culture as being created and maintained by the ways people interact and in how individuals interpret each other ’ s actions . Proponents of this theory conceptualize human interactions as a continuous process of deriving meaning from both objects in the environment and the actions of others . This is where the term symbolic comes into play . Every object and action has a symbolic meaning , and language serves as a means for people to represent and communicate their interpretations of these meanings to others . Those who believe in symbolic interactionism perceive culture as highly dynamic and fluid , as it is dependent on how meaning is interpreted and how individuals interact when conveying these meanings .", "hl_sentences": "At the core of conflict theory is the effect of economic production and materialism : dependence on technology in rich nations versus a lack of technology and education in poor nations . People who have less power also have less ability to adapt to cultural change . In the US culture of capitalism , to illustrate , we continue to strive toward the promise of the American dream , which perpetuates the belief that the wealthy deserve their privileges .", "question": { "cloze_format": "A sociologist conducts research into the ways that Hispanic American students are historically underprivileged in the American education system. The theoretical approach that the sociologist is using is ___.", "normal_format": "A sociologist conducts research into the ways that Hispanic American students are historically underprivileged in the American education system. What theoretical approach is the sociologist using?", "question_choices": [ "Symbolic interactionism", "Functionalism", "Conflict theory", "Ethnocentrism" ], "question_id": "fs-id1740738", "question_text": "A sociologist conducts research into the ways that Hispanic American students are historically underprivileged in the American education system. What theoretical approach is the sociologist using?" }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 1, "ans_text": "Functionalism" }, "bloom": "3", "hl_context": "<hl> Functionalists view society as a system in which all parts work — or function — together to create society as a whole . <hl> In this way , societies need culture to exist . Cultural norms function to support the fluid operation of society , and cultural values guide people in making choices . Just as members of a society work together to fulfill a society ’ s needs , culture exists to meet its members ’ basic needs .", "hl_sentences": "Functionalists view society as a system in which all parts work — or function — together to create society as a whole .", "question": { "cloze_format": "(The) ___ is a theoretical perspective that views society as having a system of interdependent inherently connected parts.", "normal_format": "What theoretical perspective views society as having a system of interdependent inherently connected parts?", "question_choices": [ "Sociobiology", "Functionalism", "Conflict theory", "Ethnocentrism" ], "question_id": "fs-id1757928", "question_text": "What theoretical perspective views society as having a system of interdependent inherently connected parts?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 2, "ans_text": "Conflict theory" }, "bloom": "3", "hl_context": "At the core of conflict theory is the effect of economic production and materialism : dependence on technology in rich nations versus a lack of technology and education in poor nations . <hl> Conflict theorists believe that a society ’ s system of material production has an effect on the rest of culture . <hl> People who have less power also have less ability to adapt to cultural change . This view contrasts with the perspective of functionalism . <hl> In the US culture of capitalism , to illustrate , we continue to strive toward the promise of the American dream , which perpetuates the belief that the wealthy deserve their privileges . <hl> <hl> Symbolic interactionism is a sociological perspective that is most concerned with the face-to-face interactions between members of society . <hl> Interactionists see culture as being created and maintained by the ways people interact and in how individuals interpret each other ’ s actions . Proponents of this theory conceptualize human interactions as a continuous process of deriving meaning from both objects in the environment and the actions of others . This is where the term symbolic comes into play . Every object and action has a symbolic meaning , and language serves as a means for people to represent and communicate their interpretations of these meanings to others . Those who believe in symbolic interactionism perceive culture as highly dynamic and fluid , as it is dependent on how meaning is interpreted and how individuals interact when conveying these meanings .", "hl_sentences": "Conflict theorists believe that a society ’ s system of material production has an effect on the rest of culture . In the US culture of capitalism , to illustrate , we continue to strive toward the promise of the American dream , which perpetuates the belief that the wealthy deserve their privileges . Symbolic interactionism is a sociological perspective that is most concerned with the face-to-face interactions between members of society .", "question": { "cloze_format": "The sociological theory that the “American Dream”—the notion that anybody can be successful and rich if they work hard enough—is most commonly associated with ___.", "normal_format": "The “American Dream”—the notion that anybody can be successful and rich if they work hard enough—is most commonly associated with which sociological theory?", "question_choices": [ "Sociobiology", "Functionalism", "Conflict theory", "Ethnocentrism" ], "question_id": "fs-id13146162", "question_text": "The “American Dream”—the notion that anybody can be successful and rich if they work hard enough—is most commonly associated with which sociological theory?" }, "references_are_paraphrase": 0 } ]
3
3.1 What Is Culture? Humans are social creatures. Since the dawn of Homo sapiens nearly 250,000 years ago, people have grouped together into communities in order to survive. Living together, people form common habits and behaviors—from specific methods of childrearing to preferred techniques for obtaining food. In modern-day Paris, many people shop daily at outdoor markets to pick up what they need for their evening meal, buying cheese, meat, and vegetables from different specialty stalls. In the United States, the majority of people shop once a week at supermarkets, filling large carts to the brim. How would a Parisian perceive U.S. shopping behaviors that Americans take for granted? Almost every human behavior, from shopping to marriage to expressions of feelings, is learned. In the United States, people tend to view marriage as a choice between two people, based on mutual feelings of love. In other nations and in other times, marriages have been arranged through an intricate process of interviews and negotiations between entire families, or in other cases, through a direct system such as a “mail order bride.” To someone raised in New York City, the marriage customs of a family from Nigeria may seem strange, or even wrong. Conversely, someone from a traditional Kolkata family might be perplexed with the idea of romantic love as the foundation for marriage lifelong commitment. In other words, the way in which people view marriage depends largely on what they have been taught. Behavior based on learned customs is not a bad thing. Being familiar with unwritten rules helps people feel secure and “normal.” Most people want to live their daily lives confident that their behaviors will not be challenged or disrupted. But even an action as seemingly simple as commuting to work evidences a great deal of cultural propriety. Take the case of going to work on public transportation. Whether commuting in Dublin, Cairo, Mumbai, or San Francisco, many behaviors will be the same in all locations, but significant differences also arise between cultures. Typically, a passenger would find a marked bus stop or station, wait for his bus or train, pay an agent before or after boarding, and quietly take a seat if one is available. But when boarding a bus in Cairo, passengers might have to run, because buses there often do not come to a full stop to take on patrons. Dublin bus riders would be expected to extend an arm to indicate that they want the bus to stop for them. And when boarding a commuter train in Mumbai, passengers must squeeze into overstuffed cars amid a lot of pushing and shoving on the crowded platforms. That kind of behavior would be considered the height of rudeness in United States, but in Mumbai it reflects the daily challenges of getting around on a train system that is taxed to capacity. In this example of commuting, culture consists of thoughts (expectations about personal space, for example) and tangible things (bus stops, trains, and seating capacity). Material culture refers to the objects or belongings of a group of people. Metro passes and bus tokens are part of material culture, as are automobiles, stores, and the physical structures where people worship. Nonmaterial culture , in contrast, consists of the ideas, attitudes, and beliefs of a society. Material and nonmaterial aspects of culture are linked, and physical objects often symbolize cultural ideas. A metro pass is a material object, but it represents a form of nonmaterial culture, namely, capitalism, and the acceptance of paying for transportation. Clothing, hairstyles, and jewelry are part of material culture, but the appropriateness of wearing certain clothing for specific events reflects nonmaterial culture. A school building belongs to material culture, but the teaching methods and educational standards are part of education’s nonmaterial culture. These material and nonmaterial aspects of culture can vary subtly from region to region. As people travel farther afield, moving from different regions to entirely different parts of the world, certain material and nonmaterial aspects of culture become dramatically unfamiliar. What happens when we encounter different cultures? As we interact with cultures other than our own, we become more aware of the differences and commonalities between others’ worlds and our own. Cultural Universals Often, a comparison of one culture to another will reveal obvious differences. But all cultures also share common elements. Cultural universals are patterns or traits that are globally common to all societies. One example of a cultural universal is the family unit: every human society recognizes a family structure that regulates sexual reproduction and the care of children. Even so, how that family unit is defined and how it functions vary. In many Asian cultures, for example, family members from all generations commonly live together in one household. In these cultures, young adults will continue to live in the extended household family structure until they marry and join their spouse’s household, or they may remain and raise their nuclear family within the extended family’s homestead. In the United States, by contrast, individuals are expected to leave home and live independently for a period before forming a family unit consisting of parents and their offspring. Anthropologist George Murdock first recognized the existence of cultural universals while studying systems of kinship around the world. Murdock found that cultural universals often revolve around basic human survival, such as finding food, clothing, and shelter, or around shared human experiences, such as birth and death, or illness and healing. Through his research, Murdock identified other universals including language, the concept of personal names, and, interestingly, jokes. Humor seems to be a universal way to release tensions and create a sense of unity among people (Murdock 1949). Sociologists consider humor necessary to human interaction because it helps individuals navigate otherwise tense situations. Sociological Research Is Music a Cultural Universal? Imagine that you are sitting in a theater, watching a film. The movie opens with the heroine sitting on a park bench, a grim expression on her face. Cue the music. The first slow and mournful notes are played in a minor key. As the melody continues, the heroine turns her head and sees a man walking toward her. The music slowly gets louder, and the dissonance of the chords sends a prickle of fear running down your spine. You sense that the heroine is in danger. Now imagine that you are watching the same movie, but with a different soundtrack. As the scene opens, the music is soft and soothing, with a hint of sadness. You see the heroine sitting on the park bench and sense her loneliness. Suddenly, the music swells. The woman looks up and sees a man walking toward her. The music grows fuller, and the pace picks up. You feel your heart rise in your chest. This is a happy moment. Music has the ability to evoke emotional responses. In television shows, movies, even commercials, music elicits laughter, sadness, or fear. Are these types of musical cues cultural universals? In 2009, a team of psychologists, led by Thomas Fritz of the Max Planck Institute for Human Cognitive and Brain Sciences in Leipzig, Germany, studied people’s reactions to music they’d never heard (Fritz et al. 2009). The research team traveled to Cameroon, Africa, and asked Mafa tribal members to listen to Western music. The tribe, isolated from Western culture, had never been exposed to Western culture and had no context or experience within which to interpret its music. Even so, as the tribal members listened to a Western piano piece, they were able to recognize three basic emotions: happiness, sadness, and fear. Music, it turns out, is a sort of universal language. Researchers also found that music can foster a sense of wholeness within a group. In fact, scientists who study the evolution of language have concluded that originally language (an established component of group identity) and music were one (Darwin 1871). Additionally, since music is largely nonverbal, the sounds of music can cross societal boundaries more easily than words. Music allows people to make connections where language might be a more difficult barricade. As Fritz and his team found, music and the emotions it conveys can be cultural universals. Ethnocentrism and Cultural Relativism Despite how much humans have in common, cultural differences are far more prevalent than cultural universals. For example, while all cultures have language, analysis of particular language structures and conversational etiquette reveal tremendous differences. In some Middle Eastern cultures, it is common to stand close to others in conversation. North Americans keep more distance, maintaining a large “personal space.” Even something as simple as eating and drinking varies greatly from culture to culture. If your professor comes into an early morning class holding a mug of liquid, what do you assume she is drinking? In the United States, it’s most likely filled with coffee, not Earl Grey tea, a favorite in England, or Yak Butter tea, a staple in Tibet. The way cuisines vary across cultures fascinates many people. Some travelers pride themselves on their willingness to try unfamiliar foods, like celebrated food writer Anthony Bourdain, while others return home expressing gratitude for their native culture’s fare. Often, Americans express disgust at other cultures’ cuisine, thinking it’s gross to eat meat from a dog or guinea pig, for example, while they don’t question their own habit of eating cows or pigs. Such attitudes are an example of ethnocentrism , or evaluating and judging another culture based on how it compares to one’s own cultural norms. Ethnocentrism, as sociologist William Graham Sumner (1906) described the term, involves a belief or attitude that one’s own culture is better than all others. Almost everyone is a little bit ethnocentric. For example, Americans tend to say that people from England drive on the “wrong” side of the road, rather than the “other” side. Someone from a country where dog meat is standard fare might find it off-putting to see a dog in a French restaurant—not on the menu, but as a pet and patron’s companion. A high level of appreciation for one’s own culture can be healthy; a shared sense of community pride, for example, connects people in a society. But ethnocentrism can lead to disdain or dislike for other cultures, causing misunderstanding and conflict. People with the best intentions sometimes travel to a society to “help” its people, seeing them as uneducated or backward; essentially inferior. In reality, these travelers are guilty of cultural imperialism , the deliberate imposition of one’s own cultural values on another culture. Europe’s colonial expansion, begun in the 16th century, was often accompanied by a severe cultural imperialism. European colonizers often viewed the people in the lands they colonized as uncultured savages who were in need of European governance, dress, religion, and other cultural practices. A more modern example of cultural imperialism may include the work of international aid agencies who introduce agricultural methods and plant species from developed countries while overlooking indigenous varieties and agricultural approaches that are better suited to the particular region. Ethnocentrism can be so strong that when confronted with all the differences of a new culture, one may experience disorientation and frustration. In sociology, we call this culture shock . A traveler from Chicago might find the nightly silence of rural Montana unsettling, not peaceful. An exchange student from China might be annoyed by the constant interruptions in class as other students ask questions—a practice that is considered rude in China. Perhaps the Chicago traveler was initially captivated with Montana’s quiet beauty and the Chinese student was originally excited to see an American-style classroom firsthand. But as they experience unanticipated differences from their own culture, their excitement gives way to discomfort and doubts about how to behave appropriately in the new situation. Eventually, as people learn more about a culture, they recover from culture shock. Culture shock may appear because people aren’t always expecting cultural differences. Anthropologist Ken Barger (1971) discovered this when conducting participatory observation in an Inuit community in the Canadian Arctic. Originally from Indiana, Barger hesitated when invited to join a local snowshoe race. He knew he’d never hold his own against these experts. Sure enough, he finished last, to his mortification. But the tribal members congratulated him, saying, “You really tried!” In Barger’s own culture, he had learned to value victory. To the Inuit people, winning was enjoyable, but their culture valued survival skills essential to their environment: how hard someone tried could mean the difference between life and death. Over the course of his stay, Barger participated in caribou hunts, learned how to take shelter in winter storms, and sometimes went days with little or no food to share among tribal members. Trying hard and working together, two nonmaterial values, were indeed much more important than winning. During his time with the Inuit tribe, Barger learned to engage in cultural relativism. Cultural relativism is the practice of assessing a culture by its own standards rather than viewing it through the lens of one’s own culture. Practicing cultural relativism requires an open mind and a willingness to consider, and even adapt to, new values and norms. However, indiscriminately embracing everything about a new culture is not always possible. Even the most culturally relativist people from egalitarian societies—ones in which women have political rights and control over their own bodies—would question whether the widespread practice of female genital mutilation in countries such as Ethiopia and Sudan should be accepted as a part of cultural tradition. Sociologists attempting to engage in cultural relativism, then, may struggle to reconcile aspects of their own culture with aspects of a culture they are studying. Sometimes when people attempt to rectify feelings of ethnocentrism and develop cultural relativism, they swing too far to the other end of the spectrum. Xenocentrism is the opposite of ethnocentrism, and refers to the belief that another culture is superior to one’s own. (The Greek root word xeno, pronounced “ZEE-no,” means “stranger” or “foreign guest.”) An exchange student who goes home after a semester abroad or a sociologist who returns from the field may find it difficult to associate with the values of their own culture after having experienced what they deem a more upright or nobler way of living. Perhaps the greatest challenge for sociologists studying different cultures is the matter of keeping a perspective. It is impossible for anyone to keep all cultural biases at bay; the best we can do is strive to be aware of them. Pride in one’s own culture doesn’t have to lead to imposing its values on others. And an appreciation for another culture shouldn’t preclude individuals from studying it with a critical eye. Sociology in the Real World Overcoming Culture Shock During her summer vacation, Caitlin flew from Chicago to Madrid to visit Maria, the exchange student she’d befriended the previous semester. In the airport, she heard rapid, musical Spanish being spoken all around her. Exciting as it was, she felt isolated and disconnected. Maria’s mother kissed Caitlin on both cheeks when she greeted her. Her imposing father kept his distance. Caitlin was half asleep by the time supper was served—at 10 pm! Maria’s family sat at the table for hours, speaking loudly, gesturing, and arguing about politics, a taboo dinner subject in Caitlin’s house. They served wine and toasted their honored guest. Caitlin had trouble interpreting her hosts’ facial expressions, and didn’t realize she should make the next toast. That night, Caitlin crawled into a strange bed, wishing she hadn’t come. She missed her home and felt overwhelmed by the new customs, language, and surroundings. She’d studied Spanish in school for years—why hadn’t it prepared her for this? What Caitlin hadn’t realized was that people depend not only on spoken words, but on subtle cues like gestures and facial expressions, to communicate. Cultural norms accompany even the smallest nonverbal signals (DuBois 1951). They help people know when to shake hands, where to sit, how to converse, and even when to laugh. We relate to others through a shared set of cultural norms, and ordinarily, we take them for granted. For this reason, culture shock is often associated with traveling abroad, although it can happen in one’s own country, state, or even hometown. Anthropologist Kalervo Oberg (1960) is credited with first coining the term “culture shock.” In his studies, Oberg found that most people found encountering a new culture to be exciting at first. But bit by bit, they became stressed by interacting with people from a different culture who spoke another language and used different regional expressions. There was new food to digest, new daily schedules to follow, and new rules of etiquette to learn. Living with this constant stress can make people feel incompetent and insecure. People react to frustration in a new culture, Oberg found, by initially rejecting it and glorifying one’s own culture. An American visiting Italy might long for a “real” pizza or complain about the unsafe driving habits of Italians compared to people in the United States. It helps to remember that culture is learned. Everyone is ethnocentric to an extent, and identifying with one’s own country is natural. Caitlin’s shock was minor compared to that of her friends Dayar and Mahlika, a Turkish couple living in married student housing on campus. And it was nothing like that of her classmate Sanai. Sanai had been forced to flee war torn Bosnia with her family when she was fifteen. After two weeks in Spain, Caitlin had developed a bit more compassion and understanding for what those people had gone through. She understood that adjusting to a new culture takes time. It can take weeks or months to recover from culture shock, and years to fully adjust to living in a new culture. By the end of Caitlin’s trip, she’d made new lifelong friends. She’d stepped out of her comfort zone. She’d learned a lot about Spain, but she’d also discovered a lot about herself and her own culture. 3.2 Elements of Culture Values and Beliefs The first, and perhaps most crucial, elements of culture we will discuss are its values and beliefs. Values are a culture’s standard for discerning what is good and just in society. Values are deeply embedded and critical for transmitting and teaching a culture’s beliefs. Beliefs are the tenets or convictions that people hold to be true. Individuals in a society have specific beliefs, but they also share collective values. To illustrate the difference, Americans commonly believe in the American Dream—that anyone who works hard enough will be successful and wealthy. Underlying this belief is the American value that wealth is good and important. Values help shape a society by suggesting what is good and bad, beautiful and ugly, sought or avoided. Consider the value the culture the United States places upon youth. Children represent innocence and purity, while a youthful adult appearance signifies sexuality. Shaped by this value, individuals spend millions of dollars each year on cosmetic products and surgeries to look young and beautiful. The United States also has an individualistic culture, meaning people place a high value on individuality and independence. In contrast, many other cultures are collectivist, meaning the welfare of the group and group relationships are a primary value. Living up to a culture’s values can be difficult. It’s easy to value good health, but it’s hard to quit smoking. Marital monogamy is valued, but many spouses engage in infidelity. Cultural diversity and equal opportunities for all people are valued in the United States, yet the country’s highest political offices have been dominated by white men. Values often suggest how people should behave, but they don’t accurately reflect how people do behave. Values portray an ideal culture , the standards society would like to embrace and live up to. But ideal culture differs from real culture , the way society actually is, based on what occurs and exists. In an ideal culture, there would be no traffic accidents, murders, poverty, or racial tension. But in real culture, police officers, lawmakers, educators, and social workers constantly strive to prevent or repair those accidents, crimes, and injustices. American teenagers are encouraged to value celibacy. However, the number of unplanned pregnancies among teens reveals that not only is the ideal hard to live up to, but that the value alone is not enough to spare teenagers from the potential consequences of having sex. One way societies strive to put values into action is through rewards, sanctions, and punishments. When people observe the norms of society and uphold its values, they are often rewarded. A boy who helps an elderly woman board a bus may receive a smile and a “thank you.” A business manager who raises profit margins may receive a quarterly bonus. People sanction certain behaviors by giving their support, approval, or permission, or by instilling formal actions of disapproval and non-support. Sanctions are a form of social control , a way to encourage conformity to cultural norms. Sometimes people conform to norms in anticipation or expectation of positive sanctions: good grades, for instance, may mean praise from parents and teachers. When people go against a society’s values, they are punished. A boy who shoves an elderly woman aside to board the bus first may receive frowns or even a scolding from other passengers. A business manager who drives away customers will likely be fired. Breaking norms and rejecting values can lead to cultural sanctions such as earning a negative label—lazy, no-good bum—or to legal sanctions such as traffic tickets, fines, or imprisonment. Values are not static; they vary across time and between groups as people evaluate, debate, and change collective societal beliefs. Values also vary from culture to culture. For example, cultures differ in their values about what kinds of physical closeness are appropriate in public. It’s rare to see two male friends or coworkers holding hands in the United States where that behavior often symbolizes romantic feelings. But in many nations, masculine physical intimacy is considered natural in public. This difference in cultural values came to light when people reacted to photos of former president George W. Bush holding hands with the Crown Prince of Saudi Arabia in 2005. A simple gesture, such as hand-holding, carries great symbolic differences across cultures. Norms So far, the examples in this chapter have often described how people are expected to behave in certain situations—for example, when buying food or boarding a bus. These examples describe the visible and invisible rules of conduct through which societies are structured, or what sociologists call norms. Norms define how to behave in accordance with what a society has defined as good, right, and important, and most members of the society adhere to them. Formal norms are established, written rules. They are behaviors worked out and agreed upon in order to suit and serve the most people. Laws are formal norms, but so are employee manuals, college entrance exam requirements, and “no running” signs at swimming pools. Formal norms are the most specific and clearly stated of the various types of norms, and the most strictly enforced. But even formal norms are enforced to varying degrees, reflected in cultural values. For example, money is highly valued in the United States, so monetary crimes are punished. It’s against the law to rob a bank, and banks go to great lengths to prevent such crimes. People safeguard valuable possessions and install antitheft devices to protect homes and cars. A less strictly enforced social norm is driving while intoxicated. While it’s against the law to drive drunk, drinking is for the most part an acceptable social behavior. And though there are laws to punish drunk driving, there are few systems in place to prevent the crime. These examples show a range of enforcement in formal norms. There are plenty of formal norms, but the list of informal norms —casual behaviors that are generally and widely conformed to—is longer. People learn informal norms by observation, imitation, and general socialization. Some informal norms are taught directly—“Kiss your Aunt Edna” or “Use your napkin”—while others are learned by observation, including observations of the consequences when someone else violates a norm. But although informal norms define personal interactions, they extend into other systems as well. Think back to the discussion of fast food restaurants at the beginning of this chapter. In the United States, there are informal norms regarding behavior at these restaurants. Customers line up to order their food, and leave when they are done. They don’t sit down at a table with strangers, sing loudly as they prepare their condiments, or nap in a booth. Most people don’t commit even benign breaches of informal norms. Informal norms dictate appropriate behaviors without the need of written rules. Sociological Research Breaching Experiments Sociologist Harold Garfinkel (1917–2011) studied people’s customs in order to find out how societal rules and norms not only influenced behavior but shaped social order. He believed that members of society together create a social order (Weber 2011). His resulting book, Studies in Ethnomethodology , published in 1967, discusses people’s assumptions about the social make-up of their communities. One of his research methods was known as a “breaching experiment.” His breaching experiments tested sociological concepts of social norms and conformity. In a breaching experiment, the researcher behaves in a socially awkward manner. The participants are not aware an experiment is in progress. If the breach is successful, however, these “innocent bystanders” will respond in some way. For example, if the experimenter is, say, a man in a business suit, and he skips down the sidewalk or hops on one foot, the passersby are likely to stare at him with surprised expressions on their faces. But the experimenter does not simply “act weird” in public. Rather, the point is to deviate from a specific social norm in a small way, to subtly break some form of social etiquette, and see what happens. To conduct his ethnomethodology, Garfinkel deliberately imposed strange behaviors on unknowing people. Then he would observe their responses. He suspected that odd behaviors would shatter conventional expectations, but he wasn’t sure how. He set up, for example, a simple game of tic-tac-toe. One player was asked beforehand not to mark Xs and Os in the boxes but on the lines dividing the spaces instead. The other player, in the dark about the study, was flabbergasted and did not know how to continue. Their reactions of outrage, anger, puzzlement, or other emotions illustrated the existence of cultural norms that constitute social life. These cultural norms play an important role. They let us know how to behave around each other and how to feel comfortable in our community. There are many rules about speaking with strangers in public. It’s okay to tell a woman you like her shoes. It’s not okay to ask if you can try them on. It’s okay to stand in line behind someone at the ATM. It’s not okay to look over their shoulder as they make their transaction. It’s okay to sit beside someone on a crowded bus. It’s weird to sit beside a stranger in a half-empty bus. For some breaches, the researcher directly engages with innocent bystanders. An experimenter might strike up a conversation in a public bathroom, where it’s common to respect each other’s privacy so fiercely as to ignore other people’s presence. In a grocery store, an experimenter might take a food item out of another person’s grocery cart, saying, “That looks good! I think I’ll try it.” An experimenter might sit down at a table with others in a fast food restaurant, or follow someone around a museum, studying the same paintings. In those cases, the bystanders are pressured to respond, and their discomfort illustrates how much we depend on social norms. Breaching experiments uncover and explore the many unwritten social rules we live by. Norms may be further classified as either mores or folkways. Mores (mor-ays) are norms that embody the moral views and principles of a group. Violating them can have serious consequences. The strongest mores are legally protected with laws or other formal norms. In the United States, for instance, murder is considered immoral, and it’s punishable by law (a formal norm). But more often, mores are judged and guarded by public sentiment (an informal norm). People who violate mores are seen as shameful. They can even be shunned or banned from some groups. The mores of the U.S. school system require that a student’s writing be in the student’s own words or use special forms (such as quotation marks and a whole system of citation) for crediting other writers. Writing another person’s words as if they are one’s own has a name—plagiarism. The consequences for violating this norm are severe, and can usually result in expulsion. Unlike mores, folkways are norms without any moral underpinnings. Rather, folkways direct appropriate behavior in the day-to-day practices and expressions of a culture. Folkways indicate whether to shake hands or kiss on the cheek when greeting another person. They specify whether to wear a tie and blazer or a T-shirt and sandals to an event. In Canada, women can smile and say hello to men on the street. In Egypt, it’s not acceptable. In regions in the southern United States, bumping into an acquaintance means stopping to chat. It’s considered rude not to, no matter how busy one is. In other regions, people guard their privacy and value time efficiency. A simple nod of the head is enough. Many folkways are actions we take for granted. People need to act without thinking to get seamlessly through daily routines; they can’t stop and analyze every action (Sumner 1906). People who experience culture shock may find that it subsides as they learn the new culture’s folkways and are able to move through their daily routines more smoothly Folkways might be small manners, learned by observation and imitated, but they are by no means trivial. Like mores and laws, these norms help people negotiate their daily life within a given culture. Symbols and Language Humans, consciously and subconsciously, are always striving to make sense of their surrounding world. Symbols —such as gestures, signs, objects, signals, and words—help people understand the world. Symbols provide clues to understanding experiences. They convey recognizable meanings that are shared by societies. The world is filled with symbols. Sports uniforms, company logos, and traffic signs are symbols. In some cultures, a gold ring is a symbol of marriage. Some symbols are highly functional; stop signs, for instance, provide useful instruction. As physical objects, they belong to material culture, but because they function as symbols, they also convey nonmaterial cultural meanings. Some symbols are only valuable in what they represent. Trophies, blue ribbons, or gold medals, for example, serve no other purpose other than to represent accomplishments. But many objects have both material and nonmaterial symbolic value. A police officer’s badge and uniform are symbols of authority and law enforcement. The sight of an officer in uniform or a squad car triggers reassurance in some citizens, and annoyance, fear, or anger in others. It’s easy to take symbols for granted. Few people challenge or even think about stick figure signs on the doors of public bathrooms. But those figures are more than just symbols that tell men and women which bathrooms to use. They also uphold the value, in the United States, that public restrooms should be gender exclusive. Even though stalls are relatively private, most places don’t offer unisex bathrooms. Symbols often get noticed when they are used out of context. Used unconventionally, symbols convey strong messages. A stop sign on the door of a corporation makes a political statement, as does a camouflage military jacket worn in an antiwar protest. Together, the semaphore signals for “N” and “D” represent nuclear disarmament—and form the well-known peace sign (Westcott 2008). Today, some college students have taken to wearing pajamas and bedroom slippers to class, clothing that was formerly associated only with privacy and bedtime. Though students might deny it, the outfit defies traditional cultural norms and makes a statement. Even the destruction of symbols is symbolic. Effigies representing public figures are beaten to demonstrate anger at certain leaders. In 1989, crowds tore down the Berlin Wall, a decades-old symbol of the division between East and West Germany, communism, and capitalism. While different cultures have varying systems of symbols, there is one that is common to all: language. Language is a symbolic system through which people communicate and through which culture is transmitted. Some languages contain a system of symbols used for written communication, while others rely only on spoken communication and nonverbal actions. Societies often share a single language, and many languages contain the same basic elements. An alphabet is a written system made of symbolic shapes that refer to spoken sound. Taken together, these symbols convey specific meanings. The English alphabet uses a combination of 26 letters to create words; these 26 letters make up over 600,000 recognized English words (OED Online 2011). Rules for speaking and writing vary even within cultures, most notably by region. Do you refer to a can of carbonated liquid as “soda,” pop,” or “Coke”? Is a household entertainment room a “family room,” “rec room,” or “den”? When leaving a restaurant, do you ask your server for a “check,” the “ticket,” or your “bill”? Language is constantly evolving as societies create new ideas. In this age of technology, people have adapted almost instantly to new nouns such as “e-mail” and “Internet,” and verbs such as “downloading,” “texting,” and “blogging.” Twenty years ago, the general public would have considered these nonsense words. Even while it constantly evolves, language continues to shape our reality. This insight was established in the 1920s by two linguists, Edward Sapir and Benjamin Whorf. They believed that reality is culturally determined, and that any interpretation of reality is based on a society’s language. To prove this point, the sociologists argued that every language has words or expressions specific to that language. In the United States, for example, the number 13 is associated with bad luck. In Japan, however, the number four is considered unlucky, since it is pronounced similarly to the Japanese word for “death.” The Sapir-Whorf hypothesis is based on the idea that people experience their world through their language, and that they therefore understand their world through the culture embedded in their language. The hypothesis, which has also been called linguistic relativity, states that language shapes thought (Swoyer 2003). Studies have shown, for instance, that unless people have access to the word “ambivalent,” they don’t recognize an experience of uncertainty due to conflicting positive and negative feelings about one issue. Essentially, the hypothesis argues, if a person can’t describe the experience, the person is not having the experience. In addition to using language, people communicate without words. Nonverbal communication is symbolic, and, as in the case of language, much of it is learned through one’s culture. Some gestures are nearly universal: smiles often represent joy and crying often represents sadness. Other nonverbal symbols vary across cultural contexts in their meaning. A thumbs-up, for example, indicates positive reinforcement in the United States, whereas in Russia and Australia, it is an offensive curse (Passero 2002). Other gestures vary in meaning depending on the situation and the person. A wave of the hand can mean many things, depending on how it’s done and for whom. It may mean “hello,” “goodbye,” “no thank you,” or “I’m royalty.” Winks convey a variety of messages, including “We have a secret,” “I’m only kidding,” or “I’m attracted to you.” From a distance, a person can understand the emotional gist of two people in conversation just by watching their body language and facial expressions. Furrowed brows and folded arms indicate a serious topic, possibly an argument. Smiles, with heads lifted and arms open, suggest a lighthearted, friendly chat. Social Policy and Debate Is the United States Bilingual? In 1991, when she was 6 years old, Lucy Alvarez attended a school that allowed for the use of both English and Spanish. Lucy’s teacher was bilingual, the librarian offered bilingual books, and many of the school staff spoke both Spanish and English. Lucy and many of her classmates who spoke only Spanish at home were lucky. According to the U.S. Census, 13.8 percent of U.S. residents speak a non-English language at home. That’s a significant figure, but not enough to ensure that Lucy would be encouraged to use her native language in school (Mount 2010). Lucy’s parents, who moved to Texas from Mexico, struggled under the pressure to speak English. Lucy might easily have gotten lost and left behind if she’d felt the same pressure in school. In 2008, researchers from Johns Hopkins University conducted a series of studies on the effects of bilingual education (Slavin et al. 2008). They found that students taught in both their native tongue and English make better progress than those taught only in English. Technically, the United States has no official language. But many believe English to be the rightful language of the United States, and over 30 states have passed laws specifying English as the official tongue. Proponents of English-only laws suggest that a national ruling will save money on translation, printing, and human resource costs, including funding for bilingual teachers. They argue that setting English as the official language will encourage non-English speakers to learn English faster and adapt to the culture of the United States more easily (Mount 2010). Groups such as the American Civil Liberties Union (ACLU) oppose making English the official language, claiming that it violates the rights of non-English speakers. English-only laws, they believe, deny the reality of our nation’s diversity and unfairly target Latinos and Asians. They point to the fact that much of the debate on this topic has risen since 1970, a time when the United States experienced new waves of immigration from Asia and Mexico. Today, a lot of product information gets written in multiple languages. Enter a store like Home Depot and you’ll find signs in both English and Spanish. Buy a children’s product and the safety warnings will be presented in multiple languages. While marketers are financially motivated to reach the largest number of consumers possible, this trend also may help people acclimate to a culture of bilingualism. Studies show that most American immigrants eventually abandon their native tongue and become fluent in English. Bilingual education helps with that transition. Today, Lucy Alvarez is an ambitious and high-achieving college student. Fluent in both English and Spanish, Lucy is studying law enforcement, a field that seeks bilingual employees. The same bilingualism that contributed to her success in grade school will help her thrive professionally as a law officer serving her community. 3.3 Pop Culture, Subculture, and Cultural Change It may seem obvious that there are a multitude of cultural differences between societies in the world. After all, we can easily see that people vary from one society to the next. It’s natural that a young woman from rural Kenya would have a very different view of the world from an elderly man in Mumbai—one of the most populated cities in the world. Additionally, each culture has its own internal variations. Sometimes the differences between cultures are not nearly as large as the differences inside cultures. High Culture and Popular Culture Do you prefer listening to opera or hip hop music? Do you like watching horse racing or NASCAR? Do you read books of poetry or celebrity magazines? In each pair, one type of entertainment is considered high-brow and the other low-brow. Sociologists use the term high culture to describe the pattern of cultural experiences and attitudes that exist in the highest class segments of a society. People often associate high culture with intellectualism, political power, and prestige. In America, high culture also tends to be associated with wealth. Events considered high culture can be expensive and formal—attending a ballet, seeing a play, or listening to a live symphony performance. The term popular culture refers to the pattern of cultural experiences and attitudes that exist in mainstream society. Popular culture events might include a parade, a baseball game, or the season finale of a TV show. Rock and pop music—“pop” short for “popular”—are part of popular culture. In modern times, popular culture is often expressed and spread via commercial media such as radio, television, movies, the music industry, publishers, and corporate-run websites. Unlike high culture, popular culture is known and accessible to most people. You can share a discussion of favorite football teams with a new coworker, or comment on “American Idol” when making small talk in line at the grocery store. But if you tried to launch into a deep discussion on the classical Greek play Antigone , few members of American society today would be familiar with it. Although high culture may be viewed as superior to popular culture, the labels of high culture and popular culture vary over time and place. Shakespearean plays, considered pop culture when they were written, are now among our society’s high culture. Five hundred years from now, will our descendants associate watching Two and a Half Men with members of the cultural elite? Subculture and Counterculture A subculture is just as it sounds—a smaller cultural group within a larger culture; people of a subculture are part of the larger culture, but also share a specific identity within a smaller group. Thousands of subcultures exist within the United States. Ethnic and racial groups share the language, food, and customs of their heritage. Other subcultures are united by shared experiences. Biker culture revolves around a dedication to motorcycles. Some subcultures are formed by members who possess traits or preferences that differ from the majority of a society’s population. The body modification community embraces aesthetic additions to the human body, such as tattoos, piercings, and certain forms of plastic surgery. In the United States, adolescents often form subcultures to develop a shared youth identity. Alcoholics Anonymous offers support to those suffering from alcoholism. But even as members of a subculture band together, they still identify with and participate in the larger society. Sociologists distinguish subcultures from countercultures , which are a type of subculture that rejects some of the larger culture’s norms and values. In contrast to subcultures, which operate relatively smoothly within the larger society, countercultures might actively defy larger society by developing their own set of rules and norms to live by, sometimes even creating communities that operate outside of greater society. Cults, a word derived from culture, are also considered counterculture group. The group “Yearning for Zion” (YFZ) in Eldorado, Texas, existed outside the mainstream, and the limelight, until its leader was accused of statutory rape and underage marriage. The sect’s formal norms clashed too severely to be tolerated by U.S. law, and in 2008, authorities raided the compound, removing more than two hundred women and children from the property. The Evolution of American Hipster Subculture Skinny jeans, chunky glasses, and T-shirts with vintage logos—the American hipster is a recognizable figure in the modern United States. Based predominately in metropolitan areas, sometimes clustered around hotspots such as the Williamsburg neighborhood in New York City, hipsters define themselves through a rejection of the mainstream. As a subculture, hipsters spurn many of the values and beliefs of American culture, preferring vintage clothing to fashion and a bohemian lifestyle to one of wealth and power. While hipster culture may seem to be the new trend among young, middle-class youth, the history of the group stretches back to the early decades of the 1900s. Where did the hipster culture begin? In the early 1940s, jazz music was on the rise in the United States. Musicians were known as “hepcats” and had a smooth, relaxed quality that went against upright, mainstream life. Those who were “hep” or “hip” lived by the code of jazz, while those who were “square” lived according to society’s rules. The idea of a “hipster” was born. The hipster movement spread and young people, drawn to the music and fashion, took on attitudes and language derived from the culture of jazz. Unlike the vernacular of the day, hipster slang was purposefully ambiguous. When hipsters said, “It’s cool, man,” they meant not that everything was good, but that it was the way it was. By the 1950s, the jazz culture was winding down and many traits of hepcat culture were becoming mainstream. A new subculture was on the rise. The “Beat Generation,” a title coined by writer Jack Kerouac, were anticonformist and antimaterialistic. They were writers who listened to jazz and embraced radical politics. They bummed around, hitchhiked the country, and lived in squalor. The lifestyle spread. College students, clutching copies of Kerouac’s On the Road , dressed in berets, black turtlenecks, and black-rimmed glasses. Women wore black leotards and grew their hair long. Herb Caen, a San Francisco journalist, used the suffix from Sputnik 1 , the Russian satellite that orbited Earth in 1957, to dub the movement’s followers “Beatniks.” As the Beat Generation faded, a new, related movement began. It too focused on breaking social boundaries, but also advocated freedom of expression, philosophy, and love. It took its name from the generations before; in fact, some theorists claim that Beats themselves coined the term to describe their children. Over time, the “little hipsters” of the 1970s became known simply as “hippies.” Today’s generation of hipsters rose out of the hippie movement in the same way that hippies rose from Beats and Beats from hepcats. Although contemporary hipsters may not seem to have much in common with 1940 hipsters, the emulation of nonconformity is still there. In 2010, sociologist Mark Greif set about investigating the hipster subculture of the United States and found that much of what tied the group members together was not based on fashion or musical taste or even a specific point of contention with the mainstream. “All hipsters play at being the inventors or first adopters of novelties,” Greif wrote. “Pride comes from knowing, and deciding, what’s cool in advance of the rest of the world. Yet the habits of hatred and accusation are endemic to hipsters because they feel the weakness of everyone’s position—including their own” (Greif 2010). Much as the hepcats of jazz era opposed common culture with carefully crafted appearances of coolness and relaxation, modern hipsters reject mainstream values with a purposeful apathy. Young people are often drawn to oppose mainstream conventions, even if in the same way that others do. Ironic, cool to the point of non-caring, and intellectual, hipsters continue to embody a subculture, while simultaneously impacting mainstream culture. Cultural Change As the hipster example illustrates, culture is always evolving. Moreover, new things are added to material culture every day, and they affect nonmaterial culture as well. Cultures change when something new (say, railroads or smartphones) opens up new ways of living and when new ideas enter a culture (say, as a result of travel or globalization). Innovation: Discovery and Invention An innovation refers to an object or concept’s initial appearance in society—it’s innovative because it is markedly new. There are two ways to come across an innovative object or idea: discover it or invent it. Discoveries make known previously unknown but existing aspects of reality. In 1610, when Galileo looked through his telescope and discovered Saturn, the planet was already there, but until then, no one had known about it. When Christopher Columbus encountered America, the land was, of course, already well known to its inhabitants. However, Columbus’s discovery was new knowledge for Europeans, and it opened the way to changes in European culture, as well as to the cultures of the discovered lands. For example, new foods such as potatoes and tomatoes transformed the European diet, and horses brought from Europe changed hunting practices of Native American tribes of the Great Plains. Inventions result when something new is formed from existing objects or concepts—when things are put together in an entirely new manner. In the late 1800s and early 1900s, electric appliances were invented at an astonishing pace. Cars, airplanes, vacuum cleaners, lamps, radios, telephones, and televisions were all new inventions. Inventions may shape a culture when people use them in place of older ways of carrying out activities and relating to others, or as a way to carry out new kinds of activities. Their adoption reflects (and may shape) cultural values, and their use may require new norms for new situations. Consider the introduction of modern communication technology such as mobile phones and smartphones. As more and more people began carrying these devices, phone conversations no longer were restricted to homes, offices, and phone booths. People on trains, in restaurants, and in other public places became annoyed by listening to one-sided conversations. Norms were needed for cell phone use. Some people pushed for the idea that those who are out in the world should pay attention to their companions and surroundings. However, technology enabled a workaround: texting, which enables quiet communication, and has surpassed phoning as the chief way to meet today’s highly valued ability to stay in touch anywhere, everywhere. When the pace of innovation increases, it can lead to generation gaps. Technological gadgets that catch on quickly with one generation are sometimes dismissed by a skeptical older generation. A culture’s objects and ideas can cause not just generational but cultural gaps. Material culture tends to diffuse more quickly than nonmaterial culture; technology can spread through society in a matter of months, but it can take generations for the ideas and beliefs of society to change. Sociologist William F. Ogburn coined the term culture lag to refer to this time that elapses between when a new item of material culture is introduced and when it becomes an accepted part of nonmaterial culture (Ogburn 1957). Culture lag can also cause tangible problems. The infrastructure of the United States, built a hundred years ago or more, is having trouble supporting today’s more heavily populated and fast-paced life. Yet there is a lag in conceptualizing solutions to infrastructure problems. Rising fuel prices, increased air pollution, and traffic jams are all symptoms of culture lag. Although people are becoming aware of the consequences of overusing resources, the means to support changes takes time to achieve. Diffusion and Globalization The integration of world markets and technological advances of the last decades have allowed for greater exchange between cultures through the processes of globalization and diffusion. Beginning in the 1980s, Western governments began to deregulate social services while granting greater liberties to private businesses. As a result, world markets became dominated by multinational companies in the 1980s, a new state of affairs at that time. We have since come to refer to this integration of international trade and finance markets as globalization . Increased communications and air travel have further opened doors for international business relations, facilitating the flow not only of goods but of information and people as well (Scheuerman 2010). Today, many U.S. companies set up offices in other nations where the costs of resources and labor are cheaper. When a person in the United States calls to get information about banking, insurance, or computer services, the person taking that call may be working in India or Indonesia. Alongside the process of globalization is diffusion , or, the spread of material and nonmaterial culture. While globalization refers to the integration of markets, diffusion relates a similar process to the integration of international cultures. Middle-class Americans can fly overseas and return with a new appreciation of Thai noodles or Italian gelato. Access to television and the Internet has brought the lifestyles and values portrayed in American sitcoms into homes around the globe. Twitter feeds from public demonstrations in one nation have encouraged political protesters in other countries. When this kind of diffusion occurs, material objects and ideas from one culture are introduced into another. 3.4 Theoretical Perspectives on Culture Music, fashion, technology, and values—all are products of culture. But what do they mean? How do sociologists perceive and interpret culture based on these material and nonmaterial items? Let’s finish our analysis of culture by reviewing them in the context of three theoretical perspectives: functionalism, conflict theory, and symbolic interactionism. Functionalists view society as a system in which all parts work—or function—together to create society as a whole. In this way, societies need culture to exist. Cultural norms function to support the fluid operation of society, and cultural values guide people in making choices. Just as members of a society work together to fulfill a society’s needs, culture exists to meet its members’ basic needs. Functionalists also study culture in terms of values. Education is an important concept in the United States because it is valued. The culture of education—including material culture such as classrooms, textbooks, libraries, dormitories—supports the emphasis placed on the value of educating a society’s members. Conflict theorists view social structure as inherently unequal, based on power differentials related to issues like class, gender, race, and age. For a conflict theorist, culture is seen as reinforcing and perpetuating those inequalities and differences in power. Women strive for equality in a male-dominated society. Senior citizens struggle to protect their rights, their health care, and their independence from a younger generation of lawmakers. Advocacy groups such as the American Civil Liberties Union work to protect the rights of all races and ethnicities in the United States. Inequalities exist within a culture’s value system. Therefore, a society’s cultural norms benefit some people but hurt others. Some norms, formal and informal, are practiced at the expense of others. Women were not allowed to vote in the United States until 1920. Gay and lesbian couples have been denied the right to marry until a few recent opportunities have emerged. Racism and bigotry are very much alive today. Although cultural diversity is supposedly valued in the United States, many people still frown upon interracial marriages. Same-sex marriages are banned in most states, and polygamy—common in some cultures—is unthinkable to most Americans. At the core of conflict theory is the effect of economic production and materialism: dependence on technology in rich nations versus a lack of technology and education in poor nations. Conflict theorists believe that a society’s system of material production has an effect on the rest of culture. People who have less power also have less ability to adapt to cultural change. This view contrasts with the perspective of functionalism. In the US culture of capitalism, to illustrate, we continue to strive toward the promise of the American dream, which perpetuates the belief that the wealthy deserve their privileges. Symbolic interactionism is a sociological perspective that is most concerned with the face-to-face interactions between members of society. Interactionists see culture as being created and maintained by the ways people interact and in how individuals interpret each other’s actions. Proponents of this theory conceptualize human interactions as a continuous process of deriving meaning from both objects in the environment and the actions of others. This is where the term symbolic comes into play. Every object and action has a symbolic meaning, and language serves as a means for people to represent and communicate their interpretations of these meanings to others. Those who believe in symbolic interactionism perceive culture as highly dynamic and fluid, as it is dependent on how meaning is interpreted and how individuals interact when conveying these meanings. We began this chapter by asking what culture is. Culture is comprised of all the practices, beliefs, and behaviors of a society. Because culture is learned, it includes how people think and express themselves. While we may like to consider ourselves individuals, we must acknowledge the impact of culture; we inherit thought language that shapes our perceptions and patterned behavior, including about issues of family and friends, and faith and politics. To an extent, culture is a social comfort. After all, sharing a similar culture with others is precisely what defines societies. Nations would not exist if people did not coexist culturally. There could be no societies if people did not share heritage and language, and civilization would cease to function if people did not agree to similar values and systems of social control. Culture is preserved through transmission from one generation to the next, but it also evolves through processes of innovation, discovery, and cultural diffusion. We may be restricted by the confines of our own culture, but as humans we have the ability to question values and make conscious decisions. No better evidence of this freedom exists than the amount of cultural diversity within our own society and around the world. The more we study another culture, the better we become at understanding our own.
principles_of_accounting,_volume_2:_managerial_accounting
Summary 1.1 Define Managerial Accounting and Identify the Three Primary Responsibilities of Management The purpose of managerial accounting is to supply financial and nonfinancial information to the organization’s management and other internal decision makers. Most of the job responsibilities of a manager fit into one of three categories: planning, controlling, and evaluating. Planning involves setting goals and forming the plans to achieve those goals. Controlling involves the day-to-day activities. Its purpose is to help in planning functions and to facilitate coordination within the organization. Evaluation determines whether plans are being followed and whether progress is being made as planned toward the fulfillment of organizational goals and objectives. It also involves taking corrective measures in case of deviations identified in the course of action. 1.2 Distinguish between Financial and Managerial Accounting Managerial accounting provides information to managers and other users within the company. It has a specific focus, and the information is detailed and timely. Financial accounting follows the guidelines of the GAAP, set in place by the FASB and, in many cases, by the SEC. Managerial accounting is much more flexible and does not have to follow specific rules or guidelines. There are seven key differences between managerial accounting and financial accounting: users, types of reports produced, frequency of producing the reports, purpose of the information produced, focus of the reporting information, nature of the original information used to produce the reports, and verification of the data used to create the reports. 1.3 Explain the Primary Roles and Skills Required of Managerial Accountants Essential skills for managerial accountants include commercial awareness, collaboration, effective communication skills, strong technology talents, extensive analytical abilities, and elevated ethical values. Management accountants work with individuals at all levels of an organization from the CEO to the shop floor workers. There are many different career paths management accountants can take to work in corporations, government entities, service firms, or nonprofit organizations. There are numerous certifications that accountants can earn to improve their careers and set themselves apart from their peers. 1.4 Describe the Role of the Institute of Management Accountants and the Use of Ethical Standards Many professional organizations share resources, such as education, research, and practice development, with their members. They also enforce a code of ethics for their members. All employees within a company are expected to act ethically within their business actions. This can sometimes be difficult when the company almost promotes the idea of unethical actions. In response to several corporate scandals, the United States Congress passed the Sarbanes-Oxley Act of 2002 (SOX). Ethical codes can be helpful guidelines, but the rationale to act ethically must originate from within oneself, from personal morals and values. There are steps that provide an outline for examining ethical issues. One of the issues with ethics is that what one person, community, or even country considers unethical or wrong, another person, community, or country may have no problem with and see it as just a way of doing business. The Foreign Corrupt Practices Act of 1977 specifically prohibits payments to foreign government officials to aid in attaining or retaining business. This provision applies to all US persons and foreign firms acting within the United States. 1.5 Describe Trends in Today’s Business Environment and Analyze Their Impact on Accounting Business regulations are always being altered, global competition continues to increase, and technology provides continual disruption. Management accounting must keep up with the changes in the business environment. The fundamental difference between manufacturing organizations and service-based firms is whether the organizations produce a tangible product. Business entities have been in the lead for using technology, but they must continue to adjust quickly with the ever-advancing business technology. ERP systems help companies streamline their operations and help management respond quickly to change. Lean manufacturing, which was started in Japan by automakers, is now a widely used practice that attempts to increase productivity and eliminate waste. The philosophy of continuous improvement has led organizations to adopt practices such as TQM, JIT manufacturing, and LSS. The balanced scorecard approach uses both financial and nonfinancial measures in evaluating all attributes of the organization’s procedures. Globalization has expanded competitive borders, giving customers and companies more alternatives. Many companies have started to assess their corporation not only on financial profits, but also on their corporate social responsibility.
Chapter Outline 1.1 Define Managerial Accounting and Identify the Three Primary Responsibilities of Management 1.2 Distinguish between Financial and Managerial Accounting 1.3 Explain the Primary Roles and Skills Required of Managerial Accountants 1.4 Describe the Role of the Institute of Management Accountants and the Use of Ethical Standards 1.5 Describe Trends in Today’s Business Environment and Analyze Their Impact on Accounting Why It Matters You have been elected as the coordinator of committees for your school’s business honor society. In essence, this makes you the manager of all the committees. This is a new position that was created because the committees have never been evaluated for their effectiveness within the organization. Your job in this position is to ensure that the committees—such as recruiting, fundraising, community service, professional activities, and regional and national conference presentations—are operating within the goals put forth in the society’s mission statements, as well as to assess the effectiveness and efficiency of each committee in meeting the organization’s goals. Your starting point is to understand the overriding mission—the strategic direction and purpose—of the society. Next, you want to understand how each committee fits into the strategic goal of the society and then identify the separate goals of each committee. Once you understand the purpose and goal of each committee, it will be necessary to know how each committee is going about meeting its goals. Last, you will evaluate each committee to see if the goals are being met. Notice that in performing your role as the coordinator of committees, you will need financial information, such as budgets and financial statements, along with other nonfinancial information, for example, the society’s mission statement, each committee’s strategy statement, and records of their activities and meetings. To help assess how well the honor society and its committees are meeting their goals, you need more information than can be obtained from simply looking at the various financial documents assembled by each committee within the organization. The same is true in any business organization. Managers and other internal decision makers need more information than is available in the basic financial statements: they need information generated by the managerial accounting system.
[ { "answer": { "ans_choice": 3, "ans_text": "D" }, "bloom": null, "hl_context": "To put this in context , think about how you will spend your weekend . <hl> First , you are the manager of your own time . <hl> You must plan based on your workload and on how much time you will spend studying , exercising , sleeping , and meeting with friends . You then control how your plan is implemented by setting self-imposed or possibly group meeting – imposed deadlines , and last , you evaluate how well you carried out your plan by gathering more data — such as grades on assignments , personal fulfillment , and number of hours of sleep — to determine if you met your plans ( goals ) . <hl> Not planning , controlling , and evaluating often results in less-than-desirable outcomes , such as late assignments , too little sleep , or bad grades . <hl> In this scenario , you did not need a separate managerial accountant to help you with these functions , because you could manage planning , controlling , and evaluating on your own . However , in the business world , most businesses will have both managers and managerial accountants . Table 1.3 illustrates some examples . <hl> Managers spend their time in various stages of planning , controlling , and evaluating . <hl> Generally , higher-level managers spend more time on planning , whereas lower-level managers spend more time on evaluating . At any level , managers work closely with the managerial accounting team to help in each of these stages . Managerial accountants help determine whether plans are measurable , what controls should be implemented to carry out a plan , and what are the proper means of evaluation of those controls . This would include the type of feedback necessary for management to assess the results of their plans and actions . Management accountants generate the reports and information needed to assess the results of the various evaluations , and they help interpret the results .", "hl_sentences": "First , you are the manager of your own time . Not planning , controlling , and evaluating often results in less-than-desirable outcomes , such as late assignments , too little sleep , or bad grades . Managers spend their time in various stages of planning , controlling , and evaluating .", "question": { "cloze_format": "The managers of an organization are responsible for performing several broad functions. They are ________.", "normal_format": "The managers of an organization are responsible for performing several broad functions. Which are they?", "question_choices": [ "planning, controlling, and selling", "directing, controlling, and evaluating", "planning, evaluating, and manufacturing", "planning, controlling, and evaluating" ], "question_id": "fs-idm360965088", "question_text": "The managers of an organization are responsible for performing several broad functions. They are ________." }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 1, "ans_text": "strategic planning" }, "bloom": null, "hl_context": "To this point , we ’ ve described managerial accounting as a process . The following definition considers it a profession . Management accountants are the individuals who help management with this information . <hl> The Institute of Management Accountants ( IMA ) defines management accounting as “ a profession that involves partnering in management decision making , devising planning and performance management systems , and providing expertise in financial reporting and control to assist management in the formulation and implementation of an organization ’ s strategy . ” 4 4 “ Management Accounting Careers . ” Institute of Management Accountants . <hl> https://www.imanet.org/students/management-accounting-careers?ssopc=1", "hl_sentences": "The Institute of Management Accountants ( IMA ) defines management accounting as “ a profession that involves partnering in management decision making , devising planning and performance management systems , and providing expertise in financial reporting and control to assist management in the formulation and implementation of an organization ’ s strategy . ” 4 4 “ Management Accounting Careers . ” Institute of Management Accountants .", "question": { "cloze_format": "Management accountants help the management of an organization in their planning function through ________.", "normal_format": "Through what do management accountants help the management of an organization in their planning function?", "question_choices": [ "monitoring anti-theft systems", "strategic planning", "evaluating costs", "analyzing profits" ], "question_id": "fs-idm322662688", "question_text": "Management accountants help the management of an organization in their planning function through ________." }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 0, "ans_text": "A" }, "bloom": null, "hl_context": "Managers must ultimately determine whether the company has met the goals set in the planning phase . <hl> Evaluating , also called assessing or analyzing , involves comparing actual results against expected results , and it can occur at the product , department , division , and company levels . <hl> When there are deviations from the stated objectives , managers must decide what modifications are needed .", "hl_sentences": "Evaluating , also called assessing or analyzing , involves comparing actual results against expected results , and it can occur at the product , department , division , and company levels .", "question": { "cloze_format": "___ is a primary aspect of the evaluating function within an organization.", "normal_format": "Which of the following is a primary aspect of the evaluating function within an organization?", "question_choices": [ "comparing actual results against expected results for products, departments, divisions, or the company as a whole", "reviewing only the quantitative or financial results of the company", "setting goals", "putting controls in place for the upcoming year" ], "question_id": "fs-idm362028432", "question_text": "Which of the following is a primary aspect of the evaluating function within an organization?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 1, "ans_text": "deviations and variances" }, "bloom": null, "hl_context": "The control function helps to determine the courses of action that are taken in the implementation of a plan by helping to define and administer the steps of the plan . Essentially , the control function facilitates coordination of the plan within the organization . It is through the system of controls that the actual results of decisions made in implementing a plan can be identified and measured . <hl> Managerial accounting not only helps to determine and design control measures , it also assists by providing performance reports and control reports that focus on variances between the planned objective performance and the actual performance . <hl> Control is achieved through effective feedback , or information that is used to assess a process . Feedback allows management to evaluate the results , determine whether progress is being made , or determine whether corrective measures need to be taken . This evaluation is in the next management function .", "hl_sentences": "Managerial accounting not only helps to determine and design control measures , it also assists by providing performance reports and control reports that focus on variances between the planned objective performance and the actual performance .", "question": { "cloze_format": "During the control function, the measurements taken of the performance must be accurate enough to see ________.", "normal_format": "During the control function, the measurements taken of the performance must be accurate enough to see what?", "question_choices": [ "only positive results", "deviations and variances", "the primary focus", "only the negative results" ], "question_id": "fs-idm368069840", "question_text": "During the control function, the measurements taken of the performance must be accurate enough to see ________." }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 0, "ans_text": "A" }, "bloom": null, "hl_context": "What types of objectives are part of a strategic plan ? <hl> Strategic objectives should be diverse and will vary from company to company and from industry to industry , but some general goals can include maximizing market share , increasing short-term profits , increasing innovation , offering the best value for the cost , maintaining commitment to community programs , and exceeding environmental protection mandates . <hl> <hl> Typically , a strategic plan will span any number of years an organization chooses ( three , five , seven , or even ten years ) , and often companies will have multiple strategic plans , such as one for three years , one for five years , and one for ten years . <hl> Given the time length involved in many plans , the organization also needs to factor in the potential effects of changes in their senior executive leadership and the composition of the board of directors .", "hl_sentences": "Strategic objectives should be diverse and will vary from company to company and from industry to industry , but some general goals can include maximizing market share , increasing short-term profits , increasing innovation , offering the best value for the cost , maintaining commitment to community programs , and exceeding environmental protection mandates . Typically , a strategic plan will span any number of years an organization chooses ( three , five , seven , or even ten years ) , and often companies will have multiple strategic plans , such as one for three years , one for five years , and one for ten years .", "question": { "cloze_format": "Regarding strategic planning, it cannot be said that ___ .", "normal_format": "Which of the following is false regarding strategic planning?", "question_choices": [ "It is the sole responsibility of supervisors.", "It will span many years.", "It should include both short-term and long-term goals.", "Strategic objectives will be diverse and vary from company to company." ], "question_id": "fs-idm374518432", "question_text": "Which of the following is false regarding strategic planning?" }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 1, "ans_text": "that is often focused on the future" }, "bloom": null, "hl_context": "<hl> An understanding of managerial accounting will assist anyone in the business world in determining and understanding product costs , analyzing break-even points , and budgeting for expenses and future growth ( which will be covered in other parts of this course ) . <hl> As a manager , chief executive officer , or owner , you need to have information available at hand to answer these types of questions : Financial accounting provides information to enable stockholders , creditors , and other stakeholders to make informed decisions . This information can be used to evaluate and make decisions for an individual company or to compare two or more companies . However , the information provided by financial accounting is primarily historical and therefore is not sufficient and is often synthesized too late to be overly useful to management . Managerial accounting has a more specific focus , and the information is more detailed and timelier . Managerial accounting is not governed by GAAP , so there is unending flexibility in the types of reports and information gathered . Managerial accountants regularly calculate and manage “ what-if ” scenarios to help managers make decisions and plan for future business needs . <hl> Thus , managerial accounting focuses more on the future , while financial accounting focuses on reporting what has already happened . <hl> In addition , managerial accounting uses nonfinancial data , whereas financial accounting relies solely on financial data .", "hl_sentences": "An understanding of managerial accounting will assist anyone in the business world in determining and understanding product costs , analyzing break-even points , and budgeting for expenses and future growth ( which will be covered in other parts of this course ) . Thus , managerial accounting focuses more on the future , while financial accounting focuses on reporting what has already happened .", "question": { "cloze_format": "Managerial accounting produces information ___ .", "normal_format": "Why or Which information does managerial accounting produce?", "question_choices": [ "to meet the needs of external users", "that is often focused on the future", "to meet the needs of investors", "that follows the rules of GAAP" ], "question_id": "fs-idm319149344", "question_text": "Managerial accounting produces information:" }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 0, "ans_text": "A" }, "bloom": null, "hl_context": "Ethical Considerations Institute of Management Accountants ( IMA ) Ethical Standards Four standards of ethical conduct in management accountants ’ professional activities were developed by the Institute of Management Accountants . <hl> The four standards are competence , confidentiality , integrity , and credibility . <hl> <hl> Credibility is a key standard that is based on an accountant communicating information with fairness and objectivity , disclosing all information that is relevant to the intended users understanding , and disclosing “ delays or deficiencies in information , timeliness , processing , or internal controls in conformance with organization policy and / or applicable law . ” 6 6 Institute of Management Accountants . <hl> “ Standards of Ethical Conduct for Management Accountants . ” AccountingVerse . https://www.accountingverse.com/managerial-accounting/introduction/code-of-ethics.html To this point , we ’ ve described managerial accounting as a process . The following definition considers it a profession . <hl> Management accountants are the individuals who help management with this information . <hl> The Institute of Management Accountants ( IMA ) defines management accounting as “ a profession that involves partnering in management decision making , devising planning and performance management systems , and providing expertise in financial reporting and control to assist management in the formulation and implementation of an organization ’ s strategy . ” 4 4 “ Management Accounting Careers . ” Institute of Management Accountants . https://www.imanet.org/students/management-accounting-careers?ssopc=1", "hl_sentences": "The four standards are competence , confidentiality , integrity , and credibility . Credibility is a key standard that is based on an accountant communicating information with fairness and objectivity , disclosing all information that is relevant to the intended users understanding , and disclosing “ delays or deficiencies in information , timeliness , processing , or internal controls in conformance with organization policy and / or applicable law . ” 6 6 Institute of Management Accountants . Management accountants are the individuals who help management with this information .", "question": { "cloze_format": "Management accounting ___ .", "normal_format": "What is management accounting?", "question_choices": [ "emphasizes special-purpose information", "relates to the company as a whole", "is limited to strictly cost figures", "is controlled by GAAP" ], "question_id": "fs-idm360986992", "question_text": "Management accounting:" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 2, "ans_text": "creditors" }, "bloom": null, "hl_context": "Managerial accounting information is gathered and reported for a more specific purpose for internal users , those inside the company or organization who are responsible for managing the company ’ s business interests and executing decisions . <hl> These internal users may include management at all levels in all departments , owners , and other employees . <hl> For example , in the budget development process , a company such as Tesla may want to project the costs of producing a new line of automobiles . The managerial accountants could create a budget to estimate the costs , such as parts and labor , and after the manufacturing process has begun , they can measure the actual costs , thus determining if they are over or under their budgeted amounts . Although outside parties might be interested in this information , companies like Tesla , Microsoft , and Boeing spend significant amounts of time and money to keep their proprietary information secret . Therefore , these internal budget reports are only available to the appropriate users . While you can find a cost of goods sold schedule in the financial statements of publicly traded companies , it is difficult for outside parties to break it down in order to identify the individual costs of products and services .", "hl_sentences": "These internal users may include management at all levels in all departments , owners , and other employees .", "question": { "cloze_format": "Internal users of accounting information would not include ________.", "normal_format": "What would internal users of accounting information not include?", "question_choices": [ "managers", "employees", "creditors", "officers" ], "question_id": "fs-idm360958800", "question_text": "Internal users of accounting information would not include ________." }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 2, "ans_text": "C" }, "bloom": null, "hl_context": "<hl> The information generated from the reports of financial accountants tends to be used primarily by external users , including the creditors , tax authorities and regulators , investors , customers , competitors , and others outside the company , who rely on the financial statements and annual reports to access information about a company in order to make more informed decisions . <hl> Since these external people do not have access to the documents and records used to produce the financial statements , they depend on Generally Applied Accounting Principles ( GAAP ) . These outside users also depend greatly on the preparation of audits that are done by public accounting firms , under the guidelines and standards of either the American Institute of Certified Public Accountants ( AICPA ) , the US Securities and Exchange Commission ( SEC ) , or the Public Company Accounting Oversight Board ( PCAOB ) . <hl> Financial accounting process provides a useful level of detail for external users , such as investors and creditors , but it does not provide enough detailed information for the types of decisions made in the day-to-day operation of the business or for the types of decisions that guide the company long term . <hl> Managerial accounting is the process that allows decision makers to set and evaluate business goals by determining what information they need to make a particular decision and how to analyze and communicate this information . Let ’ s explore the role of managerial accounting in several different organizations and at different levels of the organization , and then examine the primary responsibilities of management .", "hl_sentences": "The information generated from the reports of financial accountants tends to be used primarily by external users , including the creditors , tax authorities and regulators , investors , customers , competitors , and others outside the company , who rely on the financial statements and annual reports to access information about a company in order to make more informed decisions . Financial accounting process provides a useful level of detail for external users , such as investors and creditors , but it does not provide enough detailed information for the types of decisions made in the day-to-day operation of the business or for the types of decisions that guide the company long term .", "question": { "cloze_format": "External users of accounting information would include ________.", "normal_format": "What would external users of accounting information include?", "question_choices": [ "employees", "managers", "investors", "supervisors" ], "question_id": "fs-idm322625920", "question_text": "External users of accounting information would include ________." }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 3, "ans_text": "Reports produced using management accounting must follow GAAP." }, "bloom": null, "hl_context": "<hl> Financial reports rely on structure . <hl> <hl> They are generated using accepted principles that are enforced through a vast set of rules and guidelines , also known as GAAP . <hl> As mentioned previously , companies that are publicly traded are required to have their financial statements audited on an annual basis , and companies that are not publicly traded also may be required to have their financial statements audited by their creditors . The information generated by the management accountants is intended for internal use by the company ’ s divisions , departments , or both . There are no rules , guidelines , or principles to follow . Managerial accounting is much more flexible , so the design of the managerial accounting system is difficult to standardize , and standardization is unnecessary . It depends on the nature of the industry . Different companies ( even different managers within the same company ) require different information . The most important issue is whether the reporting is useful for the planning , controlling , and evaluation purposes . <hl> Unlike managerial accounting , financial accounting is governed by rules set out by the Financial Accounting Standards Board ( FASB ) , an independent board made up of accounting professionals who determine and publicize the standards of financial accounting and reporting in the United States . <hl> <hl> Larger , publicly traded companies are also governed by the US Securities and Exchange Commission ( SEC ) , in the form of the generally accepted accounting principles ( GAAP ) , the common set of rules , standards , and procedures that publicly traded companies must follow when they are composing their financial statements . <hl>", "hl_sentences": "Financial reports rely on structure . They are generated using accepted principles that are enforced through a vast set of rules and guidelines , also known as GAAP . Unlike managerial accounting , financial accounting is governed by rules set out by the Financial Accounting Standards Board ( FASB ) , an independent board made up of accounting professionals who determine and publicize the standards of financial accounting and reporting in the United States . Larger , publicly traded companies are also governed by the US Securities and Exchange Commission ( SEC ) , in the form of the generally accepted accounting principles ( GAAP ) , the common set of rules , standards , and procedures that publicly traded companies must follow when they are composing their financial statements .", "question": { "cloze_format": "It would be incorrect to state that ___.", "normal_format": "Which of the following statements is incorrect ?", "question_choices": [ "The practice of management accounting is fairly flexible.", "The information gathered from management accounting is not required by law.", "Management accounting focuses mainly on the internal user.", "Reports produced using management accounting must follow GAAP." ], "question_id": "fs-idm368540096", "question_text": "Which of the following statements is incorrect ?" }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 0, "ans_text": "A" }, "bloom": null, "hl_context": "<hl> Stockholders of a company are the owners ; however , they elect a board of directors to manage that company for them . <hl> The board selects the officers who will implement the policies and strategic goals that the board has set in place . The chief executive officer ( CEO ) is the corporation officer who has the overall responsibility for the management of the company . The person overseeing all of the accounting and finance concerns is the chief financial officer ( CFO ) . This individual is in charge of the financial planning and record-keeping of the organization and reports to the CEO . The controller is responsible for the accounting side of the business ( accounting records , financial statements , tax returns , and internal reports ) and reports to the CFO . Also reporting to the CFO is the treasurer , who is in control of the finance side of the business ( cash position , corporation funds ) . An additional area that sometimes falls under the control of the CFO is the internal audit staff . Internal auditors supply independent assurance that a company ’ s internal control processes are effective . However , there is strong support for keeping the internal audit staff outside of the CFO , because of a possible conflict of interest .", "hl_sentences": "Stockholders of a company are the owners ; however , they elect a board of directors to manage that company for them .", "question": { "cloze_format": "The stockholders of a company are __ .", "normal_format": "What are the stockholders of a company?", "question_choices": [ "the owners", "policy setters", "responsible and liable for the financial well-being of the company", "operating within the company as independent shareholders" ], "question_id": "fs-idm268631008", "question_text": "The stockholders of a company are:" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 3, "ans_text": "reports to the board of directors" }, "bloom": null, "hl_context": "Stockholders of a company are the owners ; however , they elect a board of directors to manage that company for them . The board selects the officers who will implement the policies and strategic goals that the board has set in place . The chief executive officer ( CEO ) is the corporation officer who has the overall responsibility for the management of the company . <hl> The person overseeing all of the accounting and finance concerns is the chief financial officer ( CFO ) . <hl> <hl> This individual is in charge of the financial planning and record-keeping of the organization and reports to the CEO . <hl> The controller is responsible for the accounting side of the business ( accounting records , financial statements , tax returns , and internal reports ) and reports to the CFO . Also reporting to the CFO is the treasurer , who is in control of the finance side of the business ( cash position , corporation funds ) . An additional area that sometimes falls under the control of the CFO is the internal audit staff . Internal auditors supply independent assurance that a company ’ s internal control processes are effective . However , there is strong support for keeping the internal audit staff outside of the CFO , because of a possible conflict of interest .", "hl_sentences": "The person overseeing all of the accounting and finance concerns is the chief financial officer ( CFO ) . This individual is in charge of the financial planning and record-keeping of the organization and reports to the CEO .", "question": { "cloze_format": "The controller of a corporation ___ .", "normal_format": "What does the controller of a corporation do?", "question_choices": [ "reports to the CFO and is in charge of the finance side of the business", "reports to the CFO and is in charge of the accounting side of the business", "reports to the CEO and implements all cash policies", "reports to the board of directors" ], "question_id": "fs-idm269222848", "question_text": "The controller of a corporation:" }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 2, "ans_text": "C" }, "bloom": null, "hl_context": "<hl> Not as popular in the United States as the CPA , the Chartered Financial Analyst ( CFA ) certification is more in demand throughout Europe and Asia . <hl> This certification prepares accountants for a career in the finance and investment domains . Requirements of this credential include a bachelor ’ s degree or four years ’ worth of experience , plus passing all three sections of the exam . The exam is administered by the CFA Institute . <hl> There are three separate exams , each one taking up to six hours to complete . <hl> <hl> The exams must be completed in succession . <hl> This credential is considered one of the more rigorous ones to obtain , with a passing rate of less than 45 percent . The Enrolled Agent ( EA ) credential focuses on a career in taxation , whether it is working in tax preparation for the public , internally for a corporation , or for the government at the Internal Revenue Service ( IRS ) . The EA certification was created by the IRS to signify significant knowledge of the US tax code and the ability to apply the concepts of that code . Enrolled agents have the privilege of being able to sign tax returns as paid preparers , and they are able to represent their clients in front of the IRS . The EA certification can be obtained by passing a three-part exam covering all types of individual and business tax returns . Once the certification is obtained , enrolled agents must follow strict ethical standards and complete 72 hours of continuing education courses every three years .", "hl_sentences": "Not as popular in the United States as the CPA , the Chartered Financial Analyst ( CFA ) certification is more in demand throughout Europe and Asia . There are three separate exams , each one taking up to six hours to complete . The exams must be completed in succession .", "question": { "cloze_format": "The Chartered Financial Analyst (CFA) certification ___.", "normal_format": "What is a characteristic of the Chartered Financial Analyst (CFA) certification?", "question_choices": [ "only requires a high school diploma", "is administered by the AICPA", "consists of three separate exams that must be taken in succession", "is the most popular certification among accountants in the United States" ], "question_id": "fs-idm252832736", "question_text": "The Chartered Financial Analyst (CFA) certification:" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 2, "ans_text": "includes a two-part exam, education requirements, and a work experience requirement" }, "bloom": null, "hl_context": "The Institute of Management Accountants ( IMA ) , the professional organization for management accountants , provides research , education , a means of knowledge sharing , and practice development to its members . <hl> The IMA also issues the Certified Management Accountant ( CMA ) certification to those accountants who meet the educational requirements , pass the rigorous two-part exam , and maintain continuing professional education requirements . <hl> The CMA exam covers essential managerial accounting topics as well as topics on economics and finance . Many accountants hold both CMA and CPA certifications .", "hl_sentences": "The IMA also issues the Certified Management Accountant ( CMA ) certification to those accountants who meet the educational requirements , pass the rigorous two-part exam , and maintain continuing professional education requirements .", "question": { "cloze_format": "The Certified Management Accountant (CMA) certification ___ .", "normal_format": "What is a characteristic of the Certified Management Accountant (CMA) certification?", "question_choices": [ "signifies someone specializing in tax accounting", "requires an associate’s degree and four years of work experience", "includes a two-part exam, education requirements, and a work experience requirement", "is offered to managers who take special courses in accounting" ], "question_id": "fs-idm267382144", "question_text": "The Certified Management Accountant (CMA) certification:" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 2, "ans_text": "C" }, "bloom": null, "hl_context": "<hl> Collaboration , which involves working in cross-functional teams and earning the trust and respect of colleagues in order to complete a task , is vital to improving managerial accounting talents . <hl> They should be “ team players . ”", "hl_sentences": "Collaboration , which involves working in cross-functional teams and earning the trust and respect of colleagues in order to complete a task , is vital to improving managerial accounting talents .", "question": { "cloze_format": "The term ___ means the ability to work in cross-functional teams in order to complete a task.", "normal_format": "Which of the following terms means the ability to work in cross-functional teams in order to complete a task?", "question_choices": [ "supervisory skills", "conceptualization", "collaboration", "resource planning" ], "question_id": "fs-idm271250768", "question_text": "Which of the following terms means the ability to work in cross-functional teams in order to complete a task?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 0, "ans_text": "commercial awareness" }, "bloom": null, "hl_context": "They must have knowledge of the business in which they are working . <hl> Commercial awareness is knowing how a business is run and how it is influenced by the external environment and knowing and understanding the overall industry within which the business is operating . <hl>", "hl_sentences": "Commercial awareness is knowing how a business is run and how it is influenced by the external environment and knowing and understanding the overall industry within which the business is operating .", "question": { "cloze_format": "The term that means knowing how a business is run and how it is influenced by external forces, and knowing and understanding the overall industry is ___.", "normal_format": "Which of the following terms means knowing how a business is run and how it is influenced by external forces, and knowing and understanding the overall industry?", "question_choices": [ "commercial awareness", "conceptualization", "collaboration", "imagination" ], "question_id": "fs-idm266618368", "question_text": "Which of the following terms means knowing how a business is run and how it is influenced by external forces, and knowing and understanding the overall industry?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 2, "ans_text": "C" }, "bloom": null, "hl_context": "<hl> In response to several corporate scandals , the United States Congress passed the Sarbanes-Oxley Act of 2002 ( SOX ) , also known as the “ public company accounting reform . ” It is a federal law ( http://www.soxlaw.com/ ) that was a far-reaching reform of business practices . <hl> Its focus is primarily on public accounting firms that act as auditors of publicly traded corporations . <hl> The act intended to protect investors by enhancing the accuracy and reliability of corporate financial statements and disclosures . <hl> Thousands of corporations now must confirm that their accounting processes comply with SOX . The act itself is fairly detailed , but the most significant issues for compliance are as follows :", "hl_sentences": "In response to several corporate scandals , the United States Congress passed the Sarbanes-Oxley Act of 2002 ( SOX ) , also known as the “ public company accounting reform . ” It is a federal law ( http://www.soxlaw.com/ ) that was a far-reaching reform of business practices . The act intended to protect investors by enhancing the accuracy and reliability of corporate financial statements and disclosures .", "question": { "cloze_format": "___ is the law that protects investors from fraudulent financial accounting activity.", "normal_format": "What is the law that protects investors from fraudulent financial accounting activity?", "question_choices": [ "FASB", "SACS", "SOX", "CPAS" ], "question_id": "fs-idm360958448", "question_text": "What is the law that protects investors from fraudulent financial accounting activity?" }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 3, "ans_text": "2002" }, "bloom": null, "hl_context": "<hl> In response to several corporate scandals , the United States Congress passed the Sarbanes-Oxley Act of 2002 ( SOX ) , also known as the “ public company accounting reform . ” It is a federal law ( http://www.soxlaw.com/ ) that was a far-reaching reform of business practices . <hl> Its focus is primarily on public accounting firms that act as auditors of publicly traded corporations . The act intended to protect investors by enhancing the accuracy and reliability of corporate financial statements and disclosures . Thousands of corporations now must confirm that their accounting processes comply with SOX . The act itself is fairly detailed , but the most significant issues for compliance are as follows :", "hl_sentences": "In response to several corporate scandals , the United States Congress passed the Sarbanes-Oxley Act of 2002 ( SOX ) , also known as the “ public company accounting reform . ” It is a federal law ( http://www.soxlaw.com/ ) that was a far-reaching reform of business practices .", "question": { "cloze_format": "The Sarbanes-Oxley Act was enacted in the year ___ .", "normal_format": "What year was the Sarbanes-Oxley Act enacted?", "question_choices": [ "2007", "1992", "1997", "2002" ], "question_id": "fs-idm389767760", "question_text": "What year was the Sarbanes-Oxley Act enacted?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 1, "ans_text": "B" }, "bloom": null, "hl_context": "One of the issues with ethics is that what one person , community , or even country considers unethical or wrong may not be problematic for another person , community , or country , who see it as a way of doing business . <hl> For example , bribery in the world of business happens when an organization or representative of an organization gives money or other financial benefits to another individual , business , or official in order to gain favor or to manipulate a business decision . <hl> Bribery in the United States is illegal . However , in Russia or China , a bribe is sometimes one cost of doing business , so it is part of their culture and completely ordinary .", "hl_sentences": "For example , bribery in the world of business happens when an organization or representative of an organization gives money or other financial benefits to another individual , business , or official in order to gain favor or to manipulate a business decision .", "question": { "cloze_format": "When a representative of an organization gives money to another business official in order to gain favor and/or manipulate a business decision, this is known as ________.", "normal_format": "When a representative of an organization gives money to another business official in order to gain favor and/or manipulate a business decision, what is this known as?", "question_choices": [ "whistleblowing", "bribery", "buyer debits", "face value" ], "question_id": "fs-idm385698656", "question_text": "When a representative of an organization gives money to another business official in order to gain favor and/or manipulate a business decision, this is known as ________." }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 0, "ans_text": "FCPA" }, "bloom": null, "hl_context": "<hl> The Foreign Corrupt Practices Act ( FCPA ) was implemented in 1977 in the aftermath of disclosures of bribery of foreign bureaucrats by more than 400 US corporations . <hl> The law is broken down into two parts : the antibribery section and the accounting section . <hl> The antibribery section specifically prohibits payments to foreign government officials to aid in attaining or retaining business . <hl> This provision applies to all US persons and foreign firms acting within the United States . It also requires corporations that are listed in the United States to converge their accounting records with certain accounting provisions . These include making and keeping records that fairly represent the transactions of the company and maintaining an acceptable system of internal controls . Companies doing business outside the United States are obligated to follow this law and dedicate resources to its compliance .", "hl_sentences": "The Foreign Corrupt Practices Act ( FCPA ) was implemented in 1977 in the aftermath of disclosures of bribery of foreign bureaucrats by more than 400 US corporations . The antibribery section specifically prohibits payments to foreign government officials to aid in attaining or retaining business .", "question": { "cloze_format": "The law that specifically prohibits payments to foreign officials in order to attain business is known as ________.", "normal_format": "What is the law that specifically prohibits payments to foreign officials in order to attain business known as?", "question_choices": [ "FCPA", "AICPA", "SOX", "IFRS" ], "question_id": "fs-idm397421616", "question_text": "The law that specifically prohibits payments to foreign officials in order to attain business is known as ________." }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 3, "ans_text": "D" }, "bloom": null, "hl_context": "<hl> Evaluate the decision . <hl> ( Is the issue solved ? Did it create other issues ? ) <hl> Make a decision , and take a course of action . <hl> <hl> Establish the facts of the situation ( who , what , where , when , and how ) . <hl> Individuals who work throughout the accounting profession have a significant responsibility to the general public . Financial accountants deliver information about companies that the public uses to make major financial decisions . There must be a level of trust and confidence in the ethical behavior of these accountants . Just like others in the business world , accountants are confronted endlessly with ethical dilemmas . A high standard of ethical behavior is expected of those employed in a profession . While ethical codes are helpful guidelines , the rationale to act ethically must originate from within oneself , from personal morals and values . <hl> There are steps that can provide an outline for examining ethical issues : <hl>", "hl_sentences": "Evaluate the decision . Make a decision , and take a course of action . Establish the facts of the situation ( who , what , where , when , and how ) . There are steps that can provide an outline for examining ethical issues :", "question": { "cloze_format": "To ___ is not a step in the outline for examining ethical issues.", "normal_format": "Which of the following is not a step in the outline for examining ethical issues?", "question_choices": [ "Establish the facts of the situation.", "Evaluate each course of action.", "Make a decision.", "Confirm decision with FASB." ], "question_id": "fs-idm358559056", "question_text": "Which of the following is not a step in the outline for examining ethical issues?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 2, "ans_text": "Vendor" }, "bloom": null, "hl_context": "<hl> Learning and growth / capacity . <hl> This area evaluates the entity and its performance from the standpoint of human capital , infrastructure , culture , technology , and other areas . Are employees collaborating and sharing information ? Does everyone have access to the latest trends in training and continuing education in their areas ? <hl> Customer . <hl> The BSC also evaluates how the organization is perceived , from the customer ’ s perspective . This measures customer satisfaction , new customer growth , and market share . <hl> Financial . <hl> The financial measures are the major focus of the BSC — but not the only measures . This perspective asks questions like whether the organization is making money or whether the stockholders are pleased . The balanced scorecard ( BSC ) approach uses both financial and nonfinancial measures in evaluating all attributes of the organization ’ s procedures . This approach differs from the traditional approach of only using financial measures to evaluate a company . While financial measures are essential , they are only a portion of what needs to be evaluated . <hl> The balanced scorecard focuses on both high-level and low-level measures , using the company ’ s own strategic plan . <hl> This method assesses the organization in four separate perspectives :", "hl_sentences": "Learning and growth / capacity . Customer . Financial . The balanced scorecard focuses on both high-level and low-level measures , using the company ’ s own strategic plan .", "question": { "cloze_format": "___ is not an objective used in the balanced scorecard approach.", "normal_format": "Which of the following is not an objective used in the balanced scorecard approach?", "question_choices": [ "Customer", "Financial", "Vendor", "Learning and growth" ], "question_id": "fs-idm244218272", "question_text": "Which of the following is not an objective used in the balanced scorecard approach?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 3, "ans_text": "D" }, "bloom": null, "hl_context": "All companies want to be successful . This requires continuously trying to improve the function of the organization . <hl> A lean business model is one in which a company strives to eliminate waste in its products , services , and processes , while still fulfilling the company ’ s mission . <hl> This type of model was originally implemented by the Japanese automaker , Toyota Motor Corporation , soon after the end of World War II . The implications of an organization adopting a lean business model can be overall business improvement , but a lean business model can be difficult to implement because it often requires all systems and procedures that an organization follows to be readjusted and coordinated . Managerial accounting plays a vital role in the success and implementation of a lean business model by providing accurate cost and performance evaluation information . Entities must comprehend the nature and sources of costs and develop systems that encapsulate costs accurately . <hl> The better an organization is at controlling costs , the more it can improve its overall financial performance . <hl> <hl> Continuous improvement is the manufacturing process that rejects the ideas of “ good enough . ” It is an ongoing effort to improve processes , products , services , and practices . <hl> This philosophy has led organizations to adopt practices such as total quality management , just-in-time manufacturing , and Lean Six Sigma . The fundamental ideas of all of these involve continuous improvement ; they differ only in focus .", "hl_sentences": "A lean business model is one in which a company strives to eliminate waste in its products , services , and processes , while still fulfilling the company ’ s mission . The better an organization is at controlling costs , the more it can improve its overall financial performance . Continuous improvement is the manufacturing process that rejects the ideas of “ good enough . ” It is an ongoing effort to improve processes , products , services , and practices .", "question": { "cloze_format": "Regarding continuous improvement, it cannot be said that ___ .", "normal_format": "Which of the following is not true regarding continuous improvement?", "question_choices": [ "It applies to both service and manufacturing companies.", "It is used to reduce performance costs.", "It rejects the idea of “good enough.”", "It can be applied only to improve processes and products but not services and practices." ], "question_id": "fs-idm238153136", "question_text": "Which of the following is not true regarding continuous improvement?" }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 1, "ans_text": "corporate social responsibility" }, "bloom": null, "hl_context": "In terms of managerial accounting , sustainable business practices create many issues . Organizations need to decide what elements will be measured . <hl> For example , minimizing electricity consumption , maximizing employee safety , or reducing greenhouse gases may be the biggest issue of concern for a company . <hl> Then , the company needs to determine ways of measurement that make sense regarding those items . <hl> Companies are becoming more aware of their impact on the world , and many are creating social responsibility reports in addition to their annual reports . <hl> This type of reporting requires different types of information and analysis than the typical financial measures gathered by companies . This is sometimes referred to as the triple bottom line , as it assesses an organization ’ s performance not only relating to the profit , but also relating to the world and its people , and will be covered in Sustainability Reporting . <hl> Corporate social responsibility ( CSR ) is an organization ’ s programs that evaluate and take responsibility for the organization ’ s effects on environmental and social welfare . <hl> <hl> There are many aspects of corporate social responsibility , including the types , locations , and wages of the labor employed ; the ways in which renewable and nonrenewable resources are utilized ; how charitable organizations or local areas in which the company operates are helped ; and setting corporate employee policies such as maternity and paternity leave that promote family well-being . <hl> Although the causes and cures of climate change are open to discussion , most will agree that everyone , including corporations , should do their part to avoid further damage and improve any negative impact on the environment .", "hl_sentences": "For example , minimizing electricity consumption , maximizing employee safety , or reducing greenhouse gases may be the biggest issue of concern for a company . Companies are becoming more aware of their impact on the world , and many are creating social responsibility reports in addition to their annual reports . Corporate social responsibility ( CSR ) is an organization ’ s programs that evaluate and take responsibility for the organization ’ s effects on environmental and social welfare . There are many aspects of corporate social responsibility , including the types , locations , and wages of the labor employed ; the ways in which renewable and nonrenewable resources are utilized ; how charitable organizations or local areas in which the company operates are helped ; and setting corporate employee policies such as maternity and paternity leave that promote family well-being .", "question": { "cloze_format": "A company’s attempts to utilize sustainable business practices with regard to its employees, the environment, and society are known as ________.", "normal_format": "What are a company’s attempts to utilize sustainable business practices with regard to its employees, the environment, and society known as?", "question_choices": [ "a balanced scorecard", "corporate social responsibility", "total quality management", "value chain" ], "question_id": "fs-idm239986768", "question_text": "A company’s attempts to utilize sustainable business practices with regard to its employees, the environment, and society are known as ________." }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 3, "ans_text": "D" }, "bloom": null, "hl_context": "<hl> Kaizen ( Japanese for change for the better ) is another process that is often linked to Six Sigma ( Figure 1.12 ) . <hl> <hl> The two concepts are often used together for process improvements , as they both are designed for continuous improvement by eliminating waste and increasing efficiencies . <hl> The concept of kaizen comes from an ancient Japanese philosophy that involves continuously working toward perfection in all areas of one ’ s life . It was adopted in the business world after World War II in an effort to rebuild Japan . It centers on making small , day-to-day changes that develop into major improvements over time . The key behind the success of kaizen comes from requiring all employees — from the CEO at the top , all the way down to the shop-floor janitors — to participate by making recommendations to improve the organization . From the start of the process , it must be well defined that all recommendations are appreciated and that there will be no adverse results for participating . Workers , instead , should be rewarded for any modifications that advance the workplace . Employees become more self-assured and invested when they help improve the company .", "hl_sentences": "Kaizen ( Japanese for change for the better ) is another process that is often linked to Six Sigma ( Figure 1.12 ) . The two concepts are often used together for process improvements , as they both are designed for continuous improvement by eliminating waste and increasing efficiencies .", "question": { "cloze_format": "A process that is often linked to Six Sigma and is designed toward continuous improvement by eliminating waste is ________.", "normal_format": "What is a process that is often linked to Six Sigma and is designed toward continuous improvement by eliminating waste?", "question_choices": [ "kamikaze", "value chain", "total quality management", "kaizen" ], "question_id": "fs-idm183210528", "question_text": "A process that is often linked to Six Sigma and is designed toward continuous improvement by eliminating waste is ________." }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 1, "ans_text": "just-in-time manufacturing" }, "bloom": null, "hl_context": "<hl> Just-in-time ( JIT ) manufacturing is an inventory system that companies use to increase efficiency and decrease waste by receiving goods only as they are needed within the production process , thereby reducing warehousing costs . <hl> This method requires accurate forecasting . Managerial accountants work together with purchasing and production schedulers in keeping the flow of materials accurate and efficient .", "hl_sentences": "Just-in-time ( JIT ) manufacturing is an inventory system that companies use to increase efficiency and decrease waste by receiving goods only as they are needed within the production process , thereby reducing warehousing costs .", "question": { "cloze_format": "An inventory system that organizations use to increase efficiency and decrease waste is ________.", "normal_format": "Which of the following is true about an inventory system that organizations use to increase efficiency and decrease waste?", "question_choices": [ "corporate social responsibility", "just-in-time manufacturing", "total quality management", "Lean Six Sigma" ], "question_id": "fs-idm246436528", "question_text": "An inventory system that organizations use to increase efficiency and decrease waste is ________." }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 2, "ans_text": "C" }, "bloom": null, "hl_context": "<hl> Lean Six Sigma ( LSS ) is a quality control program that depends on a combined effort of many team members to enhance performance by analytically removing waste and diminishing variations between products . <hl> The lean component of LSS is the concept that anything that is not needed in a product or service , or any unnecessary steps that exist , add cost to the product or service and therefore should be considered waste and eliminated . The Six Sigma component of LSS has to do with the elimination of defects . Essentially , as a company becomes leaner , it should also be able to reduce defects in manufacturing or in providing a service . Fewer defects add to cost savings through the need for fewer reworked products , fewer repeat service calls , and therefore , more satisfied customers . It was developed by Motorola in 1986 and emphasized cycle-time improvement and the reduction of defects . This process has shown to be a powerful way of improving business efficiency and effectiveness . As organizations continue to modify and update their processes for optimal productivity , they must be flexible . As of 2017 , LSS had developed into a business management way of thinking that focused on customer needs , customer retention , and improvement of business products and services . There are many establishments , including Motorola , that now do LSS training . There are certifications including white belt , yellow belt , green belt , black belt , and master black belt . The belts signify an employee ’ s knowledge regarding LSS . For example , a white belt understands the terminology , structure , and idea of LSS and reports issues to green or black belts . A green belt typically manages LSS projects , and a master black belt works with upper-level management to find the areas in the business where LSS needs to be implemented , leads several LSS teams , and oversees implementation of those projects .", "hl_sentences": "Lean Six Sigma ( LSS ) is a quality control program that depends on a combined effort of many team members to enhance performance by analytically removing waste and diminishing variations between products .", "question": { "cloze_format": "A quality control program that depends on multiple team members for removing waste and diminishing defects within products is ________.", "normal_format": "What is a quality control program that depends on multiple team members for removing waste and diminishing defects within products?", "question_choices": [ "kaizen", "total quality management", "Lean Six Sigma", "a balanced scorecard" ], "question_id": "fs-idm229585104", "question_text": "A quality control program that depends on multiple team members for removing waste and diminishing defects within products is ________." }, "references_are_paraphrase": null } ]
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1.1 Define Managerial Accounting and Identify the Three Primary Responsibilities of Management Financial accounting process provides a useful level of detail for external users, such as investors and creditors, but it does not provide enough detailed information for the types of decisions made in the day-to-day operation of the business or for the types of decisions that guide the company long term. Managerial accounting is the process that allows decision makers to set and evaluate business goals by determining what information they need to make a particular decision and how to analyze and communicate this information. Let’s explore the role of managerial accounting in several different organizations and at different levels of the organization, and then examine the primary responsibilities of management. Three friends who are recent graduates from business school, Alex, Hana, and Gillian, have each just begun their first postgraduation jobs. They meet for lunch and discuss what each of their jobs entails. Alex has taken a position as a market analyst for a Fortune 500 company that operates in the shipping industry. Her first assignment is to suggest and evaluate ways the company can increase the revenue from shipping contracts by 10 percent for the year. Before tackling this project, she has a number of questions. What is the purpose of this analysis? What type of information does she need? Where would she find this information? Can she get it from a basic income statement and balance sheet? How will she know if her suggestions for pricing are creating more shipping contracts and helping to meet the company’s goal? She begins with an analysis of the company’s top fifty customers, including the prices they pay, discounts offered, discounts applied, frequency of shipments, and so on, to determine if there are price adjustments that need to be made to attract those customers to use the company’s shipping services more frequently. Hana has a position in the human resources department of a pharmaceutical company and is asked to research and analyze a new trend in compensation in which employers are forgoing raises to employees and are instead giving large bonuses for meeting certain goals. Her task is to ascertain if this new idea would be appropriate for her company. Her questions are similar to Alex’s. What information does she need? Where would she find this information? How would she determine the impact of this type of change on the business? If implemented, what information would she need to assess the success of the plan? Gillian is working in the supply chain area of a major manufacturer that produces the various mirrors found on cars and trucks. Her first assignment is to determine whether it is more cost effective and efficient for her company to make or purchase a bracket used in the assembly of the mirrors. Her questions are also similar to her friends’ questions. Why is the company considering this decision? What information does she need? Where would she find this information? Would choosing the option with the lowest cost be the correct choice? The women are surprised by how similar their questions are despite how different their jobs are. They each are assigned tasks that require them to use various forms of information from many different sources to answer an important question for their respective companies. Table 1.1 provides possible answers to each of the questions posed in these scenarios. Managerial Accounting and Various Business Roles Questions Possible Answers Alex, Marketing Analyst What is the purpose of this analysis? To determine a better way to price their services What type of information does she need? Financial and nonfinancial information, such as the number of contracts per client Where would she find this information? Financial statements, customer contracts, competitor information, and customer surveys Can she get it from a basic income statement and balance sheet? No, she would need to use many other sources of information How will she know if her suggestions for pricing are creating more shipping contracts and helping to meet the company’s goal? By using a means to evaluate the success, such as by comparing the number of contracts received from each company before the new pricing structure with the number received after the pricing change of contracts Hana, Human Resources What information does she need? Financial and nonfinancial information, such as how other companies have implemented this idea, including the amount of the bonus and the types of measures on which the bonus was measured Where would she find this information? Mostly from internal company sources, such as employee performance records, but also from industry and competitor sources How would she determine the impact of this type of change on the business? Perform surveys to determine the effect of the bonus method on employee morale and employee turnover; she could determine the effect on gross revenue of annual bonuses versus annual raises If implemented, what information would she need to assess the success of the plan? Measuring employee turnover; evaluating employee satisfaction after the change; assessing whether the performance measures being used to determine the bonus were measures that truly impacted the company in a positive manner Gillian, Supply Chain Why is the company considering this decision? Management likely wants to minimize costs, and this particular part is one they believe may be more cost effective to buy than to make What information does she need? She needs the cost to buy the part as well as all the costs that would be incurred to make the part; whether her company has the ability (capacity) to make the part; the quality of the part if they buy it compared to if they make it; the ability of a supplier of the part to deliver on time Where would she find this information? She would find the information from internal records about production costs, from cost details provided by the external producer, and from industry reports on the quality of production from the external supplier Would choosing the option with the lowest cost be the correct choice? The lowest-cost option may not be the best choice if the quality is subpar, if the part is not delivered in a timely manner and thus throws off or slows production, or if the use of a purchased part will affect the relationship between the company and the car manufacturer to whom the mirror is ultimately sold Table 1.1 The questions the women have and the answers they require show that there are many types of information that a company needs to make business decisions. Although none of these individuals is given the title of manager, they need information to help provide management with the information necessary to make decisions to move the company forward with its strategic plan. The scenarios of the three women are not unique. These types of questions occur every day in businesses across the world. Some decisions will be more clearly appropriate for higher-level management. For example, Lynx Boating Company produces three different lines of boats (sport boats, pontoon boats, and large cruisers). All three boat lines are profitable, but the pontoon boat line seems to be less profitable than the other two types of boats. Management may want to consider abandoning the pontoon line and using that additional capacity to produce one of the other more profitable lines. They would need detailed financial information in order to make such a decision. Link to Learning This short video goes inside a manufacturing process to show you how machines, people, planning, implementation, efficiency, and costs interact to arrive at a finished product. Service organizations also face decisions that require more detailed information than is available in financial accounting statements. A company’s financial statements aggregate information for the company as a whole, but for most managerial decisions, information must be gathered in a timely manner at a product, customer, or division level. For example, the management of City Hospital is considering the purchase of four new magnetic resonance imaging (MRI) machines that scan three times faster than their current machines and thus would allow the hospital’s imaging department to evaluate eight additional patients each day. Each machine costs $425,000 and will last five years before needing to be replaced. Would this be a wise investment for City Hospital? Hospital management would need the appropriate information to assess the alternatives in order to make this decision. Throughout your study of managerial accounting, you will learn about the types of information needed to make these decisions, as well as techniques for analyzing this information. First, it is important to understand the various roles managers play in the organization in order to understand the types of information and the level of detail that are needed. Most of the job responsibilities of a manager fit into one of three categories: planning, controlling, or evaluating. The model in Figure 1.2 sums up the three primary responsibilities of management and the managerial accountant’s role in the process. As you can see from the model, the function of accomplishing an entity’s mission statement is a circular, ongoing process. Planning One of the first items on a new company’s agenda is the creation of a mission statement . A mission statement is a short statement of a company’s purpose and focus. This statement should be broad enough that it will encompass future growth and changes of the company. Table 1.2 contains the mission statement of three different types of companies: a manufacturer, an e-commerce company, and a service company. Sample Mission Statements Company Mission Statement Dow Chemical “To passionately create innovation for our stakeholders at the intersection of chemistry, biology, and physics.” 1 1 “Mission and Vision.” DOW. https://www.dow.com/en-us/about-dow/our-company/mission-and-vision Starbucks “To inspire and nurture the human spirit—one person, one cup, and one neighborhood at a time.” 2 2 “Our Starbucks Mission Statement.” Starbucks. https://www.starbucks.com/about-us/company-information/mission-statement Google “Our mission is to organize the world’s information and make it universally accessible and useful.” 3 3 “About.” Google. https://www.google.com/about/ Table 1.2 Once the mission of the company has been determined, the company can begin the process of setting goals , or what the company expects to accomplish over time, and objectives , or the targets that need to be met in order to meet the company’s goals. This is known as planning . Planning occurs at all levels of an organization and can cover various periods of time. One type of planning, called strategic planning , involves setting priorities and determining how to allocate corporate resources to help an organization accomplish both short-term and long-term goals. For example, one hotel may want to be the low-price, no-frills, clean alternative, while another may decide to be the superior quality, high-price luxury hotel with many amenities. Obviously, to be successful, either of these businesses must determine the goals necessary to meet their particular strategy. Typically, a strategic plan will span any number of years an organization chooses (three, five, seven, or even ten years), and often companies will have multiple strategic plans, such as one for three years, one for five years, and one for ten years. Given the time length involved in many plans, the organization also needs to factor in the potential effects of changes in their senior executive leadership and the composition of the board of directors. What types of objectives are part of a strategic plan? Strategic objectives should be diverse and will vary from company to company and from industry to industry, but some general goals can include maximizing market share, increasing short-term profits, increasing innovation, offering the best value for the cost, maintaining commitment to community programs, and exceeding environmental protection mandates. From a managerial accounting perspective, planning involves determining steps or actions to meet the strategic or other goals of the company. For example, Daryn’s Dairy, a major producer of organic dairy products in the Midwest, has made increasing the market share of its products one of its strategic goals. However, to be truly effective, the goals need to be defined specifically. For example, the goals might be stated in terms of percentage growth, both annually and in terms of the number of markets addressed in their growth projections. Also, Daryn’s planning process would include the steps the company plans to use to implement to increase market share. These plans may include current-year plans, five-year plans, and ten-year plans. The current-year plan may be to sell the company’s products in 10 percent more stores in the states in which it currently operates. The five-year plan may be to sell the products internationally in three countries, and the ten-year plan may be to acquire their chief competitor and, thus, their customers. Each of these plans will require outlining specific steps to reach these goals and communicating those steps to the employees who will carry out or have an impact on reaching these goals and implementing these plans. Planning can involve financial and nonfinancial processes and measures. One planning tool discussed in Budgeting is the budgeting process, which requires management to assess the resources—for example, time, money, and number and type of employees needed—to meet current-year objectives. Budgeting often includes both financial data, such as worker pay rates, and nonfinancial data, such as the number of customers an employee can serve in a given time period. A retail company can plan for the expected sales volume, a hospital can plan for the number of x-rays they expect to administer, a law firm can plan the hours expected for the various types of legal services they perform, a manufacturing firm can plan for the level of quality expected in each item produced, and a utility company can plan for the level of air pollutants that are acceptable. Notice that in each of these examples, the aspect of the business that is being planned and evaluated is a qualitative (nonfinancial) factor or characteristic. In your study of managerial accounting, you will learn about many situations in which both financial and nonfinancial data or information are equally relevant. However, the qualitative aspects are typically not quantified in dollars but evaluated using some other standards, such as customers served or students advised. While these functions are initially stated in qualitative terms, most of these items would at some point be translated into a dollar value or dollar effect. In each of these examples, the managerial accounting function would help to determine the variables that would help appropriately measure the desired goal as well as plan how to quantify these measures. However, measures are only useful if tracked and used to determine their effectiveness. This is known as the control function of management. Controlling To measure whether plans are meeting objectives or goals, management must put in place ways to assess success or lack of success. Controlling involves the monitoring of the planning objectives that were put into place. For example, if you have a retail store and you have a plan to minimize shoplifting, you can implement a control, such as antitheft tags that trigger an alarm when someone removes them from the store. You could also install in the ceilings cameras that provide a different view of customers shopping and therefore may catch a thief more easily or clearly. The antitheft tags and cameras serve as your controls against shoplifting. Managerial accounting is a useful tool in the management control function. Managerial accounting helps determine the appropriate controls for measuring the success of a plan. There are many types of controls that a company can use. Some controls can be in the form of financial measures, such as the ratio for inventory turnover, which is a measure of inventory control and is defined as Cost of Goods Sold ÷ Average Inventory, or in the form of a performance measure, such as decreasing production costs by 10 percent to help guide or control the decisions made by managers. Other controls can be physical controls, such as fingerprint identification or password protection. Essentially, the controlling function in management involves helping to coordinate the day-to-day activities of a business so that these activities lead to meeting corporate goals. Without controls, it is very unlikely a plan would be successful, and it would be difficult to know if your plan was a success. Consider the plan by Daryn’s Dairy to increase market share. The plan for the first year was to increase market share by selling the company’s products in 10 percent more stores in the states in which the company already operates. How will the company implement this plan? The implementation, or carrying out, of the plan will require the company to put controls in place to measure which new stores are successfully selling the company’s products, which products are being sold the most, what the sales volume and dollar value of the new stores are, and whether the sales in these new stores are affecting the volume of sales in current stores. Without this information, the company would not know if the plan is reaching the desired result of increased market share. The control function helps to determine the courses of action that are taken in the implementation of a plan by helping to define and administer the steps of the plan. Essentially, the control function facilitates coordination of the plan within the organization. It is through the system of controls that the actual results of decisions made in implementing a plan can be identified and measured. Managerial accounting not only helps to determine and design control measures, it also assists by providing performance reports and control reports that focus on variances between the planned objective performance and the actual performance. Control is achieved through effective feedback, or information that is used to assess a process. Feedback allows management to evaluate the results, determine whether progress is being made, or determine whether corrective measures need to be taken. This evaluation is in the next management function. Evaluating Managers must ultimately determine whether the company has met the goals set in the planning phase. Evaluating , also called assessing or analyzing , involves comparing actual results against expected results, and it can occur at the product, department, division, and company levels. When there are deviations from the stated objectives, managers must decide what modifications are needed. The controls that were put into place to coordinate the implementation of a particular company plan must be evaluated so that success can be measured, or corrective action can be taken. Consider Daryn’s Dairy’s one-year plan to increase market share by selling products in 10 percent more stores in the states in which the company currently operates. Suppose one of the controls put into place is to measure the sales in the current stores to determine if selling the company’s products in new stores is adding new sales or merely moving sales from existing stores. This control measure, same-store sales, must be evaluated to determine the effect of the decision to expand the selling of products within the state. This control measure will be evaluated by comparing sales in the current year in those stores to sales from the prior year in those same stores. The results of this evaluation will help guide management in their decision to move forward with their plan, to modify the plan, or to scrap the plan. As discussed previously, not all evaluations will involve quantitative or financial measures. In expanding market share, the company wants to maintain or improve its reputation with customers and does not want the planned increased availability or easier access to their products to decrease customer perceptions of the products or the company. They could use customer surveys to evaluate the perceived effect on the company’s reputation as a result of implementing this one-year plan. However, there are many ways that companies can evaluate various controls. In addition to the financial gauges, organizations are now measuring efficiencies, customer development, employee retention, and sustainability. Managers spend their time in various stages of planning, controlling, and evaluating. Generally, higher-level managers spend more time on planning, whereas lower-level managers spend more time on evaluating. At any level, managers work closely with the managerial accounting team to help in each of these stages. Managerial accountants help determine whether plans are measurable, what controls should be implemented to carry out a plan, and what are the proper means of evaluation of those controls. This would include the type of feedback necessary for management to assess the results of their plans and actions. Management accountants generate the reports and information needed to assess the results of the various evaluations, and they help interpret the results. To put this in context, think about how you will spend your weekend. First, you are the manager of your own time. You must plan based on your workload and on how much time you will spend studying, exercising, sleeping, and meeting with friends. You then control how your plan is implemented by setting self-imposed or possibly group meeting–imposed deadlines, and last, you evaluate how well you carried out your plan by gathering more data—such as grades on assignments, personal fulfillment, and number of hours of sleep—to determine if you met your plans (goals). Not planning, controlling, and evaluating often results in less-than-desirable outcomes, such as late assignments, too little sleep, or bad grades. In this scenario, you did not need a separate managerial accountant to help you with these functions, because you could manage planning, controlling, and evaluating on your own. However, in the business world, most businesses will have both managers and managerial accountants. Table 1.3 illustrates some examples. Relating Managerial Accounting Functions to Various Business Majors   Sales Human Resources Logistics Planning What are our expected sales for each product in each geographic region? How much should be budgeted for salaries and commissions for our salespeople? How much should we budget for salary and wage increases for the year? How much should we plan to spend on safety and training for the year? Should we invest in radio-frequency identification (RFID) processors to enable computer tracking of inventory? How much raw material should be ordered and delivered to ensure timely delivery of our finished products to our customers? Controlling Are we meeting expected sales growth in each region? Are each of the salespeople meeting their sales projections? Is our projected budget for wages and salaries sufficient? Are we meeting our safety and training goals? Are our products being delivered to our customers in a timely manner, and at what cost? Are we dealing with stock-outs in inventory? If so, what is that costing us? Evaluating How do our actual sales compare to our forecasted or budgeted sales? What sales promotions are our competitors offering, and what effect is it having on our market share? Would it be cheaper to hire temporary employees to get through our “busy” season or to pay our current employees for overtime? What are the cost differences in starting our own delivery service versus continuing to use other carriers? Should we outsource the manufacturing of a component part or continue to make it ourselves? What are the price differences? Table 1.3 Your Turn Evaluating On-Campus versus Off-Campus Living The principal purpose of managerial accounting is to deliver information useful for management decision-making. Many of the techniques used in managerial accounting are useful for decisions in your everyday life. In choosing whether to live on campus or off campus, how might you use planning, controlling, and evaluating in your decision-making process? What types of financial and nonfinancial information might you need? Solution Planning: Creating a list of financial and nonfinancial goals to be accomplished in your next year in college Determining how much each alternative will cost, including utilities, food, and transportation, and creating a budget Controlling: Using an expense recording app to monitor your expenses Monitoring the effectiveness of your study time as reflected in your grades Monitoring your physical health to measure if your living arrangements are conducive to staying healthy Evaluating: Assessing the effectiveness of your living arrangements by measuring your grades, bank account, and general happiness Financial: Cost of staying in dorm versus the cost of an apartment or house Estimate of differences in other costs, such as utilities, food, and additional transportation Nonfinancial: Convenience of location of dorm versus apartment or house Quality of living experience including number of roommates, ability to have own room, study environment differences Length of rental term of dorm versus apartment or house Where you plan to live in the summer, what you plan to do during that time Think It Through US Small Business Administration Many students who study managerial accounting will work for a small business, and some may even own a small business. In order to operate a small business, you need an understanding of managerial accounting, among other skills. The US Small Business Administration is an agency within the federal government that has the sole purpose of supporting small businesses. You can find a plethora of information on their website, https://www.sba.gov/. What are some of the steps in creating a small business? What are the top ten reasons given for a business failure? How could an understanding of managerial accounting help a small business owner? 1.2 Distinguish between Financial and Managerial Accounting Now that you have a basic understanding of managerial accounting , consider how it is similar to and different from financial accounting . After completing a financial accounting class, many students do not look forward to another semester of debits, credits, and journal entries. Thankfully, managerial accounting is much different from financial accounting. Also known as management accounting or cost accounting , managerial accounting provides information to managers and other users within the company in order to make more informed decisions. The overriding roles of managers (planning, controlling, and evaluating) lead to the distinction between financial and managerial accounting. The main objective of management accounting is to provide useful information to managers to assist them in the planning, controlling, and evaluating roles. Unlike managerial accounting, financial accounting is governed by rules set out by the Financial Accounting Standards Board (FASB) , an independent board made up of accounting professionals who determine and publicize the standards of financial accounting and reporting in the United States. Larger, publicly traded companies are also governed by the US Securities and Exchange Commission (SEC), in the form of the generally accepted accounting principles (GAAP) , the common set of rules, standards, and procedures that publicly traded companies must follow when they are composing their financial statements. Financial accounting provides information to enable stockholders, creditors, and other stakeholders to make informed decisions. This information can be used to evaluate and make decisions for an individual company or to compare two or more companies. However, the information provided by financial accounting is primarily historical and therefore is not sufficient and is often synthesized too late to be overly useful to management. Managerial accounting has a more specific focus, and the information is more detailed and timelier. Managerial accounting is not governed by GAAP, so there is unending flexibility in the types of reports and information gathered. Managerial accountants regularly calculate and manage “what-if” scenarios to help managers make decisions and plan for future business needs. Thus, managerial accounting focuses more on the future, while financial accounting focuses on reporting what has already happened. In addition, managerial accounting uses nonfinancial data, whereas financial accounting relies solely on financial data. For example, Daryn’s Dairy makes many different organic dairy products. Daryn’s managers need to track their costs for certain jobs. One of the company’s top-selling ice creams is their seasonal variety; a new flavor is introduced every three months and sold for only a six-month period. The cost of these specialty ice creams is different from the cost of the standard flavors for reasons such as the unique or expensive ingredients and the specialty packaging. Daryn wants to compare the costs involved in making the specialty ice cream and those involved in making the standard flavors of ice cream. This analysis will require that Daryn track not only the cost of materials that go into the product, but also the labor hours and cost of the labor, plus other costs, known as overhead costs (rent, electricity, insurance, etc.), that are incurred in producing the various ice creams. Once the total costs for both the specialty ice cream and the standard flavored ice cream are known, the cost per unit can be determined for each type. These types of analyses help a company evaluate how to set pricing, evaluate the need for new or substitute ingredients, manage product additions and deletions, and make many other decisions. Figure 1.3 shows an example of a materials cost analysis by Daryn’s Dairy used to compare the materials cost for producing 500 gallons of their best-selling standard flavor—vanilla—with one of their specialty ice creams—Very Berry Biscotti. Financial and Managerial Accounting Comparative Managerial and financial accounting are used by every business, and there are important differences in their reporting functions. Those differences are detailed in Figure 1.4 . Users of Reports The information generated from the reports of financial accountants tends to be used primarily by external users , including the creditors, tax authorities and regulators, investors, customers, competitors, and others outside the company, who rely on the financial statements and annual reports to access information about a company in order to make more informed decisions. Since these external people do not have access to the documents and records used to produce the financial statements, they depend on Generally Applied Accounting Principles (GAAP). These outside users also depend greatly on the preparation of audits that are done by public accounting firms, under the guidelines and standards of either the American Institute of Certified Public Accountants (AICPA), the US Securities and Exchange Commission (SEC), or the Public Company Accounting Oversight Board (PCAOB). Managerial accounting information is gathered and reported for a more specific purpose for internal users , those inside the company or organization who are responsible for managing the company’s business interests and executing decisions. These internal users may include management at all levels in all departments, owners, and other employees. For example, in the budget development process, a company such as Tesla may want to project the costs of producing a new line of automobiles. The managerial accountants could create a budget to estimate the costs, such as parts and labor, and after the manufacturing process has begun, they can measure the actual costs, thus determining if they are over or under their budgeted amounts. Although outside parties might be interested in this information, companies like Tesla , Microsoft , and Boeing spend significant amounts of time and money to keep their proprietary information secret. Therefore, these internal budget reports are only available to the appropriate users. While you can find a cost of goods sold schedule in the financial statements of publicly traded companies, it is difficult for outside parties to break it down in order to identify the individual costs of products and services. Link to Learning Investopedia is considered to be the largest Internet financial education resource in the world. There are many short, helpful videos that explain various concepts of managerial accounting. Watch this video explaining managerial accounting and how useful it can be to many different types of managers to learn more. Types of Reports Financial accounting information is communicated through reporting , such as the financial statements. The financial statements typically include a balance sheet, income statement, cash flow statement, retained earnings statement, and footnotes. Managerial accounting information is communicated through reporting as well. However, the reports are more detailed and more specific and can be customized. One example of a managerial accounting report is a budget analysis (variance report) as shown in Figure 1.5 . Other reports can include cost of goods manufactured, job order cost sheets, and production reports. Since managerial accounting is not governed by GAAP or other constraints, it is important for the creator of the reports to disclose all assumptions used to make the report. Since the reports are used internally, and not typically released to the general public, the presentation of any assumptions does not have to follow any industry-wide guidelines. Each organization is free to structure its reports in the format that organizes its information in the best way for it. This type of analysis helps management to evaluate how effective they were at carrying out the plans and meeting the goals of the corporation. You will see many examples of reports and analyses that can be used as tools to help management make decisions. Think It Through Projection Error You are working as the accountant in the special projects and budgets area of Sturm, Ruger & Company, a law firm that currently specializes in bankruptcy law. In order to serve their customers better and more efficiently, the company is trying to decide whether or not to expand its services and offer credit counseling, credit monitoring, credit rebuilding, and identity protection services. The president comes to you and asks for some sales and revenue projections. He would like the projections in three days’ time so that he can present the results to the board at the annual meeting. You work tirelessly for two straight days compiling projections of sales and revenues to prepare the reports. The report is provided to the president just before the board is to arrive. When you return to your office, you start clearing away some of the materials that you used in your report, and you discover an error that makes all of your projections significantly overstated. You ask the president’s administrative assistant if the president has presented the report to the board, and you find that he had mentioned it but not given the full report as of yet. What would you do? What are the ethical concerns in this matter? What would be the results of telling the president of your error? What would be the results of not telling the president of your error? Frequency of Reports The financial statements are typically generated quarterly and annually, although some entities also require monthly statements. Much work is involved in creating the financial statements, and any adjustments to accounts must be made before the statements can be produced. A physical count inventory must be done to adjust the inventory and cost of goods sold accounts, depreciation must be calculated and entered, all prepaid asset accounts must be reviewed for adjustments, and so forth. The annual reports are not finalized for several weeks after the year-end, because they are based on historical data; for a company that is traded on one of the major or regional stock exchanges, it must have an audit of the financial statements conducted by an independent certified public accountant. This audit cannot be completed until after the end of the company’s fiscal year, because the auditors need access to all of the information for the company for that year. For companies that are privately held, an audit is not normally required. However, potential lenders might require an independent audit. Conversely, managers can quickly attain managerial accounting information. No external, independent auditors are needed, and it is not necessary to wait until the year-end. Projections and estimates are adequate. Managers should understand that in order to obtain information quickly, they must accept less precision in the reporting. While there are several reports that are created on a regular basis (e.g., budgets and variance reports), many management reports are produced on an as-needed basis. Purpose of Reports The general purpose of financial statement reporting is to provide information about the results of operations, financial position, and cash flows of an organization. This data is useful to a wide range of users in order to make economic decisions. The purpose of the reporting done by management accountants is more specific to internal users. Management accountants make available the information that could assist companies in increasing their performance and profitability. Unlike financial reports, management reporting centers on components of the business. By dividing the business into smaller sections, a company is able to get into the details and analyze the smallest segments of the business. An understanding of managerial accounting will assist anyone in the business world in determining and understanding product costs, analyzing break-even points, and budgeting for expenses and future growth (which will be covered in other parts of this course). As a manager, chief executive officer, or owner, you need to have information available at hand to answer these types of questions: Are my profits higher this quarter over last quarter? Do I have enough cash flow to pay my employees? Are my jobs priced correctly? Are my products priced correctly in order for me to make the profit I need to make? Who are my most productive and least productive employees? In the world of business, information is power; stated simply, the more you know, typically, the better your decisions can be. Managerial accounting delivers data-driven feedback for these decisions that can assist in improving decision-making over the long term. Business managers can leverage this powerful tool in order to make their businesses more successful, because management accounting adds value to common business decision-making. All of this readily available information can lead to great improvements for any business. Focus of Reports Because financial accounting typically focuses on the company as a whole, external users of this information choose to invest or loan money to the entire company, not to a department or division within the company. Therefore, the global focus of financial accounting is understandable. However, the focus of management accounting is typically different. Managerial reporting is more focused on divisions, departments, or any component of a business, down to individuals. The mid-level and lower-level managers are typically responsible for smaller subsets within the company. Managers need accounting reports that deal specifically with their division and their specific activities. For instance, production managers are responsible for their specific area and the results within their division. Accordingly, these production managers need information about results achieved in their division, as well as individual results of departments within the division. The company can be broken into segments based on what managers need—for example, geographic location, product line, customer demographics (e.g., gender, age, race), or any of a variety of other divisions. Nature of Reports Both financial reports and managerial reports use monetary accounting information , or information relating to money or currency. Financial reports use data from the accounting system that is gathered from the reporting of transactions in the form of journal entries and then aggregated into financial statements. This information is monetary in nature. Managerial accounting uses some of the same financial information as financial accounting, but much of that information will be broken down to a more detailed level. For example, in financial reporting, net sales are needed for the income statement. In managerial accounting, the quantity and dollar value of the sales of each product are likely more useful. In addition, managerial accounting uses a significant amount of nonmonetary accounting information , such as quantity of material, number of employees, number of hours worked, and so forth, which does not relate to money or currency. Verification of Reports Financial reports rely on structure. They are generated using accepted principles that are enforced through a vast set of rules and guidelines, also known as GAAP. As mentioned previously, companies that are publicly traded are required to have their financial statements audited on an annual basis, and companies that are not publicly traded also may be required to have their financial statements audited by their creditors. The information generated by the management accountants is intended for internal use by the company’s divisions, departments, or both. There are no rules, guidelines, or principles to follow. Managerial accounting is much more flexible, so the design of the managerial accounting system is difficult to standardize, and standardization is unnecessary. It depends on the nature of the industry. Different companies (even different managers within the same company) require different information. The most important issue is whether the reporting is useful for the planning, controlling, and evaluation purposes. Your Turn Daryn’s Dairy Suppose you have been hired by Daryn’s Dairy as a market analyst. Your first assignment is to evaluate the sales of various standard and specialty ice creams within the Midwest region where Daryn’s Dairy operates. You also need to determine the best-selling flavors of ice cream in other regions of the United States as well as the selling patterns of the flavors. For example, do some flavors sell better than others at different times of the year, or are some top sellers sold as limited-edition flavors? Remember that one of the strategic goals of the company is to increase market share, and the first step in meeting this goal is to sell their product in 10 percent more stores within their current market, so your research will help upper-level management carry out the company’s goals. Where would you gather the information? What type of information would you need? Where would you find this information? How would the company determine the impact of this type of change on the business? If implemented, what information would you need to assess the success of the plan? Solution Answers will vary. Sample answer: Where would you gather the information? Where would you find this information? Current company sales information would be obtained from internal company reports and records that detail the sale of each type of ice cream including volume, cost, price, and profit per flavor. Sales of ice cream from other companies may be more difficult to obtain, but the footnotes and supplemental information to the annual reports of those companies being analyzed, as well as industry trade journals, would likely be good sources of information. What types of information would you need? Some of the types of information that would be needed would be the volume of sales of each flavor (number of gallons), how long each flavor has been sold, whether seasonal or limited-edition flavors are produced and sold only once or are on a rotating basis, the size of the market being examined (number of households), whether the other companies sell similar products (organic, all natural, etc.), the median income of consumers or other information to assess the consumers’ willingness to pay for organic products, and so forth. How would Daryn’s Dairy determine the impact of this type of change on the business? Management would evaluate the cost to expand into new stores in their current market compared to the potential revenues from selling their products in those stores in order to assess the ability of the potential expansion to generate a profit for the company. If implemented, what information would Daryn’s Dairy need to assess the success of the plan? Management would measure the profitability of selling any new products, expanding into new stores in their current market, or both to determine if the implementation of the plan was a success. If the plan is a success and the company is generating profits, the company will continue to figure out ways to improve efficiency and profitability. If the plan is not a success, the company will determine the reasons (cost to produce too high, sales price too high, volume too low, etc.) and make a new plan. 1.3 Explain the Primary Roles and Skills Required of Managerial Accountants It is clear that management accountants must have a solid foundation in accounting, in both financial and managerial accounting, but other than accounting skills, what makes good managerial accountants? They must have knowledge of the business in which they are working. Commercial awareness is knowing how a business is run and how it is influenced by the external environment and knowing and understanding the overall industry within which the business is operating. Collaboration , which involves working in cross-functional teams and earning the trust and respect of colleagues in order to complete a task, is vital to improving managerial accounting talents. They should be “team players.” Management accountants should have effective communication skills that allow them to convey accounting information in both written and oral forms in a way that the intended audience can understand. Being able to gather the data quickly and accurately is important, but the data is meaningless if it is not presented in an intuitive style that the audience can understand. Strong technology skills are also essential. These skills include not only accounting and reporting software but also other programs that would assist in automating processes, improving efficiencies, and adding value to the company. For many companies, additional software and accompanying technology are often needed for both their financial and managerial accounting functions. For example, enterprise resource planning (ERP) systems often play a major role in the creation of comprehensive accounting systems. This additional support is often provided by outside suppliers such as Hyperion , Cognos , Sage , SAP , PeopleSoft , and Oracle . Managerial accountants must possess extensive analytical skills. They must regularly work with financial analysts and management personnel to find ways to reduce expenses and analyze budgets. These skills include the ability to envision, verbalize, conceptualize, or solve both multifaceted and simplistic problems by making choices that make sense with the given information. Managerial accountants must have ethics and values. They should be an example to others and encourage them to follow internal control practices and procedures. Ethics is discussed in more detail in Describe the role of the Institute of Management Accountants and the use of ethical standards . Managers at all levels make many different types of decisions every day, but to make most decisions, they need specific information. Some information is easily obtainable, and some is not. Managers do not always know what information they need or what is available, and they need to know if the decisions they make are having the desired outcome and meeting specific goals. To this point, we’ve described managerial accounting as a process. The following definition considers it a profession. Management accountants are the individuals who help management with this information. The Institute of Management Accountants (IMA) defines management accounting as “a profession that involves partnering in management decision making, devising planning and performance management systems, and providing expertise in financial reporting and control to assist management in the formulation and implementation of an organization’s strategy.” 4 4 “Management Accounting Careers.” Institute of Management Accountants. https://www.imanet.org/students/management-accounting-careers?ssopc=1 The IMA also reports that nearly 75 percent of financial professionals work in business as management accountants in positions such as financial analysts, accounting managers, controllers, and chief financial officers. 5 These professionals have a significant impact on businesses through influencing the decision-making process and business strategy. 5 “Management Accounting Careers.” Institute of Management Accountants. https://www.imanet.org/students/management-accounting-careers?ssopc=1 Management accountants work at various levels of the organization, from the project level to the division level to the controller and chief financial officer. Often, management accountants work where they are needed and not necessarily at corporate headquarters. They tend to be hands-on in the decision-making process. They need many types of information to inform the many decisions they must make. Continuing Application Who Uses Managerial Accounting? When most people think of an accounting job, they think of someone who does taxes or who puts together financial statements. However, almost all jobs use accounting information, particularly managerial accounting information. Table 1.4 shows how certain professions might use managerial accounting information. Can you think of other examples? Use of Managerial Accounting Information Profession How They Use Managerial Accounting in Their Industry Engineer Properly track and report the use of resources involved in an engineering project; measure and communicate costs of a project and its outcomes Mayor Put together a budget, a planning and control mechanism that plays an important role in every government Nurse Track operating or service costing per patient, or per unit Mechanic Use job costing to figure total costs and overall profitability on each job Retail store manager Forecast inventory needs, review profit margins, and track sales margins on individual products as well as entire stores Restaurant owner Calculate the cost of serving a single table by estimating the cost of the food plus time of server, keep food costs under control through inventory tracking Architect Track direct and indirect costs for each job; track profitability per job Farmer Calculate yields per field, analyze fertilizer and seeding rates, and control waste Table 1.4 Organizational Structure Most companies have an organizational chart that displays the configuration and the delegation of authority in the decision-making processes ( Figure 1.7 ). The structure helps define roles and responsibilities. The organizational charts provide guidance to employees and other stakeholders by outlining the official reporting affiliations that direct the workflow within the organization. If the company is particularly efficient, it also will include contact information within the chart. This is a convenient directory to circulate among employees. It helps them find a particular person in a certain position, or determine whom to speak to about certain areas within the company, or even identify a specific person’s supervisor to report positive or negative work behavior. Stockholders of a company are the owners; however, they elect a board of directors to manage that company for them. The board selects the officers who will implement the policies and strategic goals that the board has set in place. The chief executive officer (CEO) is the corporation officer who has the overall responsibility for the management of the company. The person overseeing all of the accounting and finance concerns is the chief financial officer (CFO) . This individual is in charge of the financial planning and record-keeping of the organization and reports to the CEO. The controller is responsible for the accounting side of the business (accounting records, financial statements, tax returns, and internal reports) and reports to the CFO. Also reporting to the CFO is the treasurer , who is in control of the finance side of the business (cash position, corporation funds). An additional area that sometimes falls under the control of the CFO is the internal audit staff. Internal auditors supply independent assurance that a company’s internal control processes are effective. However, there is strong support for keeping the internal audit staff outside of the CFO, because of a possible conflict of interest. Think It Through Managing Cash Flow Assume you are the managerial accountant at Anchor Head Brewery, a Midwest craft brewery that distributes nationwide. Its year-end is December 31. Because of poor cash flow management, the CFO has some concerns about having enough cash to be able to pay the tax bill that is expected. In early December, the purchasing department bought excess hops, barley, malt, oats, and yeast in anticipation of brewing more beer for the holiday and Super Bowl seasons. In order to decrease the company’s net income, thereby reducing their taxable income, the CFO tells you to enter the purchase of this inventory as part of the “Supplies Expense” in the current year. In which account should these materials be recorded? How should you reply to this request? Should you bring this matter to another executive officer? Careers The field of managerial accounting, or corporate accounting, is composed of the financial and accounting responsibilities required to operate any type of business. Managerial accountants are employed within organizations to monitor costs, sales, budgets, and spending; conduct audits; predict future requirements; and aid the executive leaders of the organization with financial decision-making. Figure 1.8 lists approximate salaries for several financial and managerial accounting employment positions. In reviewing the salary information, be aware that there are often major variances in salaries based on geographical locations. For example, a cost accountant manager in San Francisco, California, would typically be paid significantly more than an accountant in a similar position in Fayetteville, Arkansas. However, the cost of living, especially housing costs, in San Francisco is also significantly higher than the cost of living in Fayetteville. Managerial accountants find employment opportunities in a wide variety of settings and industries. Professionals in this discipline are in high demand from public and private companies, government agencies, and not-for-profit entities (NFPs). Some areas of management accounting are versatile to any sector (corporate, government, or NFP). A financial analyst assists in preparing budgets, tracking actual costs, examining task performance, scrutinizing different types of variances, and supporting other management personnel in organizing forecasts and projections. A budget analyst arranges and manages the master budget and compares master budget projections to actual results. This individual must be vastly aware of all operations in the budget and work closely with the rest of the accounting staff as well as management personnel. An internal auditor typically reports to high-level executives within the company. An internal auditor is often called on to investigate budget variances, industrial sabotage, poor work quality, fraud, and theft. He or she also safeguards the internal controls and confirms they are working and effective. A cash-management accountant has responsibilities that include transferring monies between accounts, monitoring deposits and payments, reconciling cash balances, creating and tracking cash forecasts, and performing all other cash-related financial processes. Other areas of managerial accounting are specific to the sector in which accountants work. For example, the area of cost accounting is more specific to the corporate or manufacturing sector. These cost accountants amass large sums of data, checking for accuracy and then formulating the cost of raw materials, work in process, finished goods, labor, overhead, and other associated manufacturing costs. Governmental entities also use accounting to communicate with their constituents. Government agencies include all levels of government, federal, state, county, and city, including military, law enforcement, airports, and school systems. Government accountants deal with budgets, auditing, and payroll, the same as all other managerial accountants. However, they must follow a different set of accounting rules called the Governmental Accounting Standards Board (GASB). Nonprofit (not-for-profit) organizations are tax-exempt organizations that serve their communities in a variety of areas, such as religion, education, social services, health care, and the arts. Managerial accountants in this area are most often focused on budgets. The biggest difference between a corporate budget analyst and a nonprofit budget analyst is that the nonprofit analyst works the budget backward, compared to the corporate analyst. For example, if a corporation was selling widgets, its budget would start with a sales forecast of how many widgets the company thinks it can sell. This gives the company a forecast of how much it can spend on expenses and fixed assets. The nonprofit budget analysts often start with the expenses. They forecast how much the expenses will be in order to continue to offer their service to the community. From there, they then adjust how much they will need to obtain through fundraising, donations, grants, or other sources to meet their expenses. Your Turn Career Planning All companies need to plan ahead in order to continuously move forward. Their top management must take into consideration where they want the company to be in the next three to five years. Just like a company, you also need to consider where you want to be in three to five years, and you need to start taking strides now to accomplish what it is you need to in order to get there ( Figure 1.9 ). Answer the following: What job would you like to be doing in three to five years? What is your plan for getting there? Identify five to ten steps needed. Do you have a specific company you would like to be working for in the next three to five years? What are the reasons you want to work for them? In order to acquire the position you want, at the company you want, you need a résumé. Your résumé is like the company report of “you.” It needs to offer reliable information about your experiences and achievements. What are the basic elements of a résumé, and how will you provide reassurance that the information on your résumé is trustworthy? Solution Answers will vary. Sample answer: I would like to own my own home remodeling company. Steps to get there include the following: complete double major in business and building construction in the summers before graduation, work for a local handyman franchise after graduation, work for a home builder as a project manager while working, save money for five years to be used to start my own company put together a business plan start my own business six years after graduation I would like to work for a national home builder such as Pulte or Toll Brothers . Ideally, I would have an internship with one of them during college. I would like to work for a national builder or a large regional builder because they already have a good business model and I could learn how that works. My résumé needs to contain my education information such as the degree and my majors as well as classes that are pertinent to my career. It should also indicate all of my work experience and any particular skills or certifications I have achieved, such as Eagle Scout. An example of how this information may be presented on a résumé can be seen in Figure 1.10 . Certifications There are many distinct accounting certifications that accountants can earn in order to improve their careers, attain promotions, and acquire raises in their pay. The certifications are somewhat different from each other and focused toward different career paths. Many accountants have more than one of these credentials to diversify their paths. The Certified Public Accountant (CPA) is considered the top tier in accounting certifications. Many companies or positions require CPA certification. For example, most employees at accounting firms earn a CPA certificate within the first few of years of graduation. Some positions, such as controller or CFO, often require CPA certification. In the United States, each state has different educational and experience requirements in order to obtain the CPA. The certification requires passing the four-part CPA exam as well. This is administered by the American Institute of Certified Public Accountants (AICPA). There are four parts to the exam: Financial Accounting and Reporting (FAR), Auditing and Attestation (AUD), Regulation (REG), and Business Environment and Concepts (BEC). Each part is graded on a 100-point scale. A score of seventy-five or greater must be achieved in order to pass each section. The exams can be intimidating, as it is a difficult process to go through. As of 2017, the AICPA reported a pass rate of less than 50 percent, which may contribute to its high regard around the world. After passing the CPA exam, candidates must work for one year under the supervision of a licensed CPA before their own license is approved by a state regulatory agency. Those certified in public accounting work in all areas of accounting. However, do not assume that being a CPA is the only way to secure an excellent position in accounting. The Certified Management Accountant (CMA) is another top-tiered certification for accountants. The CMA title identifies the individual as a specialist in corporate accounting management. The CMA has some overlap with the CPA, but the CPA is focused more on compliance, tax, and controls. CMAs favor financial analytics, budgeting, and strategic assessment. This certification requires the minimum of a bachelor’s degree from an accredited college or university, two years of work experience, and successfully passing both parts of the exam. Part one of the exam covers financial reporting, planning, performance, and controls. Part two focuses on financial decision-making. The exam is administered by the IMA and has a 50 percent passing rate globally. Not as popular in the United States as the CPA, the Chartered Financial Analyst (CFA) certification is more in demand throughout Europe and Asia. This certification prepares accountants for a career in the finance and investment domains. Requirements of this credential include a bachelor’s degree or four years’ worth of experience, plus passing all three sections of the exam. The exam is administered by the CFA Institute. There are three separate exams, each one taking up to six hours to complete. The exams must be completed in succession. This credential is considered one of the more rigorous ones to obtain, with a passing rate of less than 45 percent. The Enrolled Agent (EA) credential focuses on a career in taxation, whether it is working in tax preparation for the public, internally for a corporation, or for the government at the Internal Revenue Service (IRS). The EA certification was created by the IRS to signify significant knowledge of the US tax code and the ability to apply the concepts of that code. Enrolled agents have the privilege of being able to sign tax returns as paid preparers, and they are able to represent their clients in front of the IRS. The EA certification can be obtained by passing a three-part exam covering all types of individual and business tax returns. Once the certification is obtained, enrolled agents must follow strict ethical standards and complete 72 hours of continuing education courses every three years. The Certified Internal Auditor (CIA) is a credential offered by the Institute of Internal Auditors (IIA) and is one of the only certifications that is accepted worldwide. CIAs tend to be employed in auditing areas within government agencies, banking, finance, or corporations. They examine financial documents to investigate deficiencies in internal controls. Requirements for this certification include a bachelor’s degree, two years of work experience in a related field, and passing the three sections of the examination. Also required are providing character references, following a code of ethics, and continuing education. The Certified Fraud Examiner (CFE) certification signifies proven proficiency in fraud prevention, detection, and deterrence. CFEs are instructed in how to identify the red flags that may indicate fraudulent actions. The designation is awarded by the Association of Certified Fraud Examiners (ACFE) after applicants have met the following requirements: bachelor’s degree, two years of work-related experience, moral character references, and the passing of four separate exams. The Certified Government Auditing Professional (CGAP) designation is exclusively for auditors employed throughout the public sector (federal, state, local) and is offered by the IIA. Requirements for this credential are the same as for the CIA. The exam has 115 multiple-choice questions and covers four areas focusing on proficiency in generally accepted government auditing standards (GAGAS). These certifications lead to different job responsibilities and different career paths. As indicated, each of the certifications requires varying degrees of education and has exams that are unique to that particular certification. All of these certifications also require a certain number of hours of continuing education in order to keep the certification active. This ensures that the certificate holder is up to date on changes in the field. There are always many opportunities throughout the year to obtain continuing education credits through seminars, webinars, symposiums, and online and in-person classes. Link to Learning Accounting.com has an application that will help to acquaint you with the different opportunities available, skill sets that may be required, and different salaries for accounting careers. See the Careers in Accounting report for more information. 1.4 Describe the Role of the Institute of Management Accountants and the Use of Ethical Standards As you’ve learned, unlike the specific rules set forth by GAAP and the SEC that govern financial accounting, managerial accounting does not have specific rules and is considered flexible, as the reporting stays internal and does not need to follow external rules. Managers of a business need detailed information in a timely manner. This means that a managerial accountant needs to understand many detailed aspects of how the company operates in addition to financial accounting methods, because the framework of typical management reports often comes from the financial statements. However, the reports can be individualized and customized to the information the manager is seeking. Each company has different strategies, timing, and needs for information. The Institute of Management Accountants (IMA) , the professional organization for management accountants, provides research, education, a means of knowledge sharing, and practice development to its members. The IMA also issues the Certified Management Accountant (CMA) certification to those accountants who meet the educational requirements, pass the rigorous two-part exam, and maintain continuing professional education requirements. The CMA exam covers essential managerial accounting topics as well as topics on economics and finance. Many accountants hold both CMA and CPA certifications. Business Ethics The IMA also develops standards and principles to help management accountants deal with ethical challenges. Trust is an important cornerstone of business interactions, both internal and external. When there is a lack of trust, it changes how decisions are made. Trust develops when there are good ethics : when people know right from wrong. Consider these three questions as put forth by the Institute of Business Ethics: (1) Do I mind others knowing what I have done? (2) Who does my decision affect or hurt? (3) Would my decision be considered fair to those affected? These questions can help evaluate the ethics of a decision. Ethics is more than simply obeying laws; it involves doing the right thing as well as the legal thing. Many companies have a code of conduct to help guide their employees. For example, Google has a code of ethics that they expect all of their employees and board members to follow. Failing to do so can cause termination of employment. The preface of the code includes “Don’t be evil.” They use that to show all employees and other shareholders within Google that they are serious about ethics—that trust and respect are essential in providing a great service to their customers. The IMA has its own Statement of Ethical Professional Practice for its members. Managerial accountants should never commit acts that violate the standards of ethics, and they should never ignore such deeds by others within their companies. Many other professional organizations, across many different professions, have codes of ethics. For example, there are codes of ethics for the AICPA, ACFE, Financial Executives International, American Marketing Association, National Society of Professional Engineers, and the American Nurses Association. Ethical Considerations Institute of Management Accountants (IMA) Ethical Standards Four standards of ethical conduct in management accountants’ professional activities were developed by the Institute of Management Accountants. The four standards are competence, confidentiality, integrity, and credibility. Credibility is a key standard that is based on an accountant communicating information with fairness and objectivity, disclosing all information that is relevant to the intended users understanding, and disclosing “delays or deficiencies in information, timeliness, processing, or internal controls in conformance with organization policy and/or applicable law.” 6 6 Institute of Management Accountants. “Standards of Ethical Conduct for Management Accountants.” AccountingVerse. https://www.accountingverse.com/managerial-accounting/introduction/code-of-ethics.html Often, when we think of unethical behavior, we imagine large-scale scenarios involving tens of thousands of dollars or more, but ethical issues are more likely faced on a small scale. For example, suppose you work for an organization that makes and sells virtual reality headsets. Because of competition, your company has decreased their forecasted sales for next year by 20 percent over the current year. In a meeting, the CEO expressed concern over the effect of the decreased sales on the bonuses of upper-level executives, since their bonus is tied to meeting income projections. The vice president of marketing suggested in the meeting that if the company simply continued to produce the same number of headsets as they had in the previous year, income levels may still be achieved in order for the bonuses to be awarded. This would involve the company producing excess inventory with hopes of selling them, in order to achieve income levels sufficiently adequate to be able to pay bonuses to executives. While a conflict of interest might not be intuitively obvious, the company (and thus its managerial accountants) has an obligation to many stakeholders such as investors, creditors, employees and the community. The obligation of a corporation to these stakeholders depends somewhat on the stakeholder. For example, the primary obligation to a creditor may be to make timely payments, the obligation to the community may be to minimize negative environmental impact. Most stakeholders to not have access to internal information or decisions and thus rely on management to be ethical in their decision-making. The company may indeed be able to sell all that it produces, but given the forecasted drop in sales, producing the same number of units as during the current year will likely lead to unsellable inventory, the need to sell the units at a significant discount in order to dispose of them, or both. Following the recommendation to produce more than forecasted sales might hurt the value of the company’s stock, which could hurt many categories of stakeholders who depend on the accountants and financial analysts to protect their financial interests. In addition to managing production and inventory, a budget and the entire budget process have an impact on managerial decision-making. Suppose you are the manager of the research department of a pharmaceutical company. Your budget includes the costs for various types of training for your staff. Because of the amount of time spent in development of a highly promising medication to treat diabetes, your staff has not had time to complete as much training during the current year as you had allowed for in the budget. You are concerned that if you do not use the training money, your training budget will be decreased in the next budget cycle. To prevent this from happening, you arrange for several online training sessions for your staff. These training sessions are on the basics of laboratory safety. All of your staff is very experienced and current on this topic and can likely go straight to the course completion quiz and complete it in a matter of minutes without actually watching any of the ten modules. What would encourage a manager to schedule and spend money on training that is not useful for the employees? While it is expected to stay within the budget, many managers will spend any “excess” amounts remaining in the budget at the end of the fiscal year. This practice is known as “use it or lose it.” Managers do this to avoid having their budgets cut in the next fiscal year. Stated simply, management spends everything in their budget regardless of the value added or the necessity. This is not ethical behavior and is usually the result of a budgetary process that needs to be modified so that the possibility of being able to pad the budget is removed or at least minimized. All employees within a company are expected to act ethically within their business actions. This can sometimes be difficult when the company itself almost promotes the idea of unethical actions. For example, Wells Fargo started offering incentives to their employees who succeeded in selling to current customers other services and products that the bank had to offer. This incentive created an unethical culture. Employees manufactured fake accounts, credit cards, and other services in order to qualify for the bonuses. In the end, 5,300 employees lost their jobs, and everyone learned a lesson on creating proper incentives. Executives who aspire to run an ethical company can do so, if they change reward systems from “pay for performance” to more holistic values. Examples of proper incentives include attendance rewards, merit rewards, team bonuses, overall profit sharing, and stock options. Link to Learning Most, if not all, major corporations have a code of ethics or a code of conduct. Read Google’s Code of Conduct and consider the following questions: What is the basic foundation for their code of conduct? What do you think it means? After reading their document, has it changed your opinion of the company? Do you think having a code of ethics or a code of conduct really matters? Ethics Legislation In response to several corporate scandals, the United States Congress passed the Sarbanes-Oxley Act of 2002 (SOX) , also known as the “public company accounting reform.” It is a federal law (http://www.soxlaw.com/) that was a far-reaching reform of business practices. Its focus is primarily on public accounting firms that act as auditors of publicly traded corporations. The act intended to protect investors by enhancing the accuracy and reliability of corporate financial statements and disclosures. Thousands of corporations now must confirm that their accounting processes comply with SOX. The act itself is fairly detailed, but the most significant issues for compliance are as follows: Section 302. The CEO and CFO must review all financial reports and sign the report. Section 404. All financial reports must be audited on an annual basis and must be accompanied by an internal control audit. Section 806. Whistleblowers , or those who provide evidence of fraud, are afforded special protections. Section 906. The criminal penalties for a fraudulent financial report are increased from pre-SOX. Penalties can be up to $5 million in fines and up to 25 years in prison. Link to Learning The Sarbanes-Oxley Act has been in place for many years now and has its champions and its critics. Read this 2017 article from Accounting Today on the benefits and negative impacts of the act to learn more. This article from ConnectUS discusses the benefits and negative impacts as well. Individuals who work throughout the accounting profession have a significant responsibility to the general public. Financial accountants deliver information about companies that the public uses to make major financial decisions. There must be a level of trust and confidence in the ethical behavior of these accountants. Just like others in the business world, accountants are confronted endlessly with ethical dilemmas. A high standard of ethical behavior is expected of those employed in a profession. While ethical codes are helpful guidelines, the rationale to act ethically must originate from within oneself, from personal morals and values. There are steps that can provide an outline for examining ethical issues: Recognize the ethical issue at hand and those involved (employees, creditors, vendors, and community). Establish the facts of the situation (who, what, where, when, and how). Recognize the competing values related to the issue (confidentiality and conflict of interest). Determine alternative courses of action (do not limit yourself). Evaluate each course of action and how each relates to the values in step 3. Recognize the possible consequences of each course of action and how each affects those involved in step 1. Make a decision, and take a course of action. Evaluate the decision. (Is the issue solved? Did it create other issues?) Ethical Considerations Ethical Dilemma You are about to sign a new client to a very large contract worth over $900,000. Your supervisor is under a lot of pressure to increase sales. He calls you into his office and tells you his future with the company is in jeopardy, and he asks you to include the revenue for the new contract in the sales figures for the quarter that ends today. You know the contract is a certainty, but the client is out of town and cannot possibly sign for at least a week. Use the eight steps in examining an ethical situation to determine how you would react to this situation. One of the issues with ethics is that what one person, community, or even country considers unethical or wrong may not be problematic for another person, community, or country, who see it as a way of doing business. For example, bribery in the world of business happens when an organization or representative of an organization gives money or other financial benefits to another individual, business, or official in order to gain favor or to manipulate a business decision. Bribery in the United States is illegal. However, in Russia or China, a bribe is sometimes one cost of doing business, so it is part of their culture and completely ordinary. The Foreign Corrupt Practices Act (FCPA) was implemented in 1977 in the aftermath of disclosures of bribery of foreign bureaucrats by more than 400 US corporations. The law is broken down into two parts: the antibribery section and the accounting section. The antibribery section specifically prohibits payments to foreign government officials to aid in attaining or retaining business. This provision applies to all US persons and foreign firms acting within the United States. It also requires corporations that are listed in the United States to converge their accounting records with certain accounting provisions. These include making and keeping records that fairly represent the transactions of the company and maintaining an acceptable system of internal controls. Companies doing business outside the United States are obligated to follow this law and dedicate resources to its compliance. The accounting section of the FCPA requires a company to have good internal controls so a slush fund to pay bribes cannot be created and maintained. A slush fund is a cash account that is often created for illegal activities or payments that are not typically recorded on the books. More details on the SOX and the FCPA are covered in such courses as auditing, intermediate accounting, cost accounting, and business law. Your Turn Logistics Analyst As a corporate accountant, it is very important to understand both financial and managerial aspects of the company and industry in which you are working. In order to assist management in their roles of planning, controlling, and evaluating, an accountant needs to be aware not only of GAAP but also of the products or services offered by the company, the processes by which those products or services are produced, and pertinent facts about suppliers, customers, and competitors. Not having this knowledge not only makes it more difficult for the corporate or managerial accountant to perform any assigned duties, but there is also an ethical responsibility to be knowledgeable in order to offer assistance, analysis, or recommendations to management or customers. Assume you have been hired by Triumph Motorcycles as a new logistics analyst. In this position, you will carry out such tasks as obtaining and analyzing information about your company’s goods or services; monitoring the production, service, and information processes and flow; and looking for ways to improve efficiency of operations. How would you go about obtaining the knowledge and understanding you will need to work for this company? How would financial and managerial accounting concepts help you in understanding the company and the industry as a whole? Solution Answers will vary. Sample answer: Ways to learn about the company and industry include the company website, press or news releases, industry trade journals, company internal documents such as procedure manuals and job descriptions, and conversations or interviews with fellow employees at various levels of the organization. The more knowledge you have regarding financial and managerial accounting, the better you can link the operations of the organizations to financial results and the more easily you can ascertain both efficiencies and inefficiencies in the organization. 1.5 Describe Trends in Today’s Business Environment and Analyze Their Impact on Accounting The business environment never rests. Regulations are always changing, global competition continues to increase, and technology provides continual disruption. Management accounting is always evolving due to changes in the business environment. The types of information needed and obtainable have changed significantly over time. Many areas of employment are impacting businesses and the managerial accounting function today. For example, more than 60 percent of workers in the United States are employed within service industries, such as government agencies, marketing firms, accounting firms, and airlines. The health-care and social service industries have doubled in size. However, as the number of service jobs has increased, the number of manufacturing jobs, as a percentage of all jobs, has been decreasing. 7 One of the primary reasons for the decline in manufacturing jobs is automation and other technological changes. 7 Dr. Patricia Buckley. “Geographic Trends in Manufacturing Job Creation: Something Old, Something New.” Deloitte Insight . September 25, 2017. https://www2.deloitte.com/insights/us/en/economy/behind-the-numbers/geographic-trends-in-manufacturing-job-creation.html How are service industries different from manufacturing organizations? The fundamental difference is the product they sell. The service company, such as a marketing, legal, or consulting firm, produces intangible goods , meaning that the product has no physical substance. Manufacturing companies produce tangible goods , which customers can handle and see. This leads to another significant difference between manufacturing companies and service firms: inventory. Service firms, unlike manufacturing, do not have large inventories, because there is no tangible product. Manufacturing will have inventories of raw materials, of goods that are in the process of being produced and goods that have been completed but not yet sold. Managerial accountants must track all of this information for manufacturing companies. However, managerial accountants are still needed within service-based firms to track time, materials, and overhead. For example, Boeing Company is a manufacturer of airplanes. Their accountants must track several different types of inventory categories, direct labor, and overhead costs, among other things. One of Boeing’s customers, Delta Air Lines , is a service-based company. The managerial accountants for the airline also are responsible for following costs, but their reports are targeted toward industry-specific measures such as operating margins, revenue from passenger miles, load factors, and passenger yield, among others. Much of managerial accounting focuses on manufacturing. However, the techniques used for cost accounting for manufacturing companies also can be applied to service-based organizations. The former would develop a cost of goods manufactured schedule, and the latter would need a cost of service schedule. The structure of the reports is principally the same, but section headings would reflect the type of organization. Technology Business entities always look for ways to leverage technology . Any type of technology that can increase production, reduce costs, or increase safety will attract attention from the business world. There are many areas of technology that businesses have used already, but to continue reaping those benefits, these companies need to adjust quickly with the ever-advancing business technology. Companies have the ability to integrate many of their business processes through enterprise resource planning (ERP) systems, which help companies streamline their operations and help management respond quickly to change. Although they are expensive, these systems help alleviate the complications that arise from business systems that do not coordinate with one another. For example, a company may have many different individual systems for each function: human resources may have a system to track employees’ insurance benefits, training, and retirement programs, while payroll may have a program that tracks employees’ earnings, taxes, deductions, and direct deposit information. Much of the information human resources and payroll collect is the same. Having one system with different silos is much more efficient than having two separate systems. Management must be aware of and adapt to whichever type of system that the business has—either one ERP or several independent systems that may not coordinate information ( Figure 1.11 ). Businesses have been on the forefront of advancing technology. As computer systems developed throughout the twentieth century, they brought with them the potential for many benefits, but the business world needed to adapt and transform their infrastructure. Over the last forty years, tangible assets (buildings, machinery, and vehicles) have declined from 80 percent of a company’s value to 15 percent, while intangible assets (trademarks, patents, and competencies) are now at an average of 85 percent of a company’s value. It can be difficult to put a value on some of the intangible assets, but it is not hard to realize they do have worth. JetBlue has the number one brand loyalty of all North American airlines. Apple has built a kingdom around brand loyalty. Intangible assets can give a company a competitive edge, entice consumers, and protect the organization’s brain trust. Technological advances can directly affect managerial accounting reports, through estimates of overhead costs. Historically, overhead was typically calculated on the basis of relatively straightforward relationships, such as direct labor costs or direct labor hours. With the advancements through automation, in many instances, direct labor costs are much lower and no longer relevant in computing overhead costs. Automation is a method of using systems such as computers or robots to operate different processes and machinery to improve efficiencies and lower direct labor costs. Companies use automation to remove the complex, superfluous stages from a process in order to streamline the practice. In essence, labor is being traded for machine production. Such industries as auto production are excellent examples. This exchange of direct labor for greater costs in overhead for such factors as machinery depreciation will be addressed in Job Order Costing and Process Costing on calculating production costs. Link to Learning Automation has changed the production of automobiles over the last 100 years. This 100-second video from Ford Motor Company on automation demonstrates this concept. With the growth of the Internet and the speed by which information is shared, businesses can now communicate with employees from around the world within seconds. This has made outsourcing common in certain sectors. Outsourcing is hiring workers outside of the company who perform their tasks inside or outside of the country. Most of the exported jobs have gone to less-developed countries, where there are lower labor costs. Outsourcing saves the company money on labor and overhead costs and has become a major trend over the past several years. More and more organizations, both large and small, are now using outsourcing as a way of growing their entities without adding additional labor and overhead costs. Outsourcing allows a company to focus on its own competencies and hire those outside sources to handle other duties. Another technology that is quickly becoming widespread is radio-frequency identification (RFID) . This technology uses electromagnetic fields to routinely identify and trace inventory tags that have been attached to objects. The tags contain information that has been stored by electronic means. The RFID tags can made into many shapes and sizes and enclosed in many different materials. These tiny devices have advantages over the common bar code. They do not need to be positioned precisely over the scanner and cannot be manipulated like barcodes. This technology has been used for many years in identifying and tracking lost pets, but it was considered too expensive for more extensive use in industry. With the advancements over the last several years, RFID devices are now seen as “throwaway” control devices. One company recently signed a contract to sell 500 million RFID tags at a cost of about ten cents per device. Other current uses include antitheft tags attached to merchandise, credit card chips, and heavy-duty transponders used in shipping containers. New uses being investigated include RFID chips in passports, food, and people. Think It Through Outsourcing With the increase in global businesses and competition, there has been an increased focus on outsourcing in order to reduce costs. As you’ve learned, outsourcing involves hiring an outside company to provide services or products rather than having them produced internally. For example, you are the vice president of operations for a manufacturing firm. Other firms similar to yours have outsourced some of the product assembly. You estimate that you could save a significant amount of money on wages and benefits, as you would let go approximately ten workers if you outsource. Would you outsource? Why or why not? Lean Practices All companies want to be successful. This requires continuously trying to improve the function of the organization. A lean business model is one in which a company strives to eliminate waste in its products, services, and processes, while still fulfilling the company’s mission. This type of model was originally implemented by the Japanese automaker, Toyota Motor Corporation , soon after the end of World War II. The implications of an organization adopting a lean business model can be overall business improvement, but a lean business model can be difficult to implement because it often requires all systems and procedures that an organization follows to be readjusted and coordinated. Managerial accounting plays a vital role in the success and implementation of a lean business model by providing accurate cost and performance evaluation information. Entities must comprehend the nature and sources of costs and develop systems that encapsulate costs accurately. The better an organization is at controlling costs, the more it can improve its overall financial performance. Continuous improvement is the manufacturing process that rejects the ideas of “good enough.” It is an ongoing effort to improve processes, products, services, and practices. This philosophy has led organizations to adopt practices such as total quality management, just-in-time manufacturing, and Lean Six Sigma. The fundamental ideas of all of these involve continuous improvement; they differ only in focus. Total quality management (TQM) concentrates on quality improvement and applies this benchmark to all aspects of business activities. In TQM, management and employees look to reveal waste and errors, streamline the supply chain, improve customer relations, and confirm that employees are informed and properly trained. The objective of TQM is continuous improvement by concentrating on systematic problem-solving and customer service. Scientific methods are used to study what succeeds and what does not, and then the best practices are implemented throughout the organization. However, the pursuit of total quality will cost the company money. With the help of management accountants, companies can track these costs and forecast whether or not the improvements will eventually save the organization money down the road. Just-in-time (JIT) manufacturing is an inventory system that companies use to increase efficiency and decrease waste by receiving goods only as they are needed within the production process, thereby reducing warehousing costs. This method requires accurate forecasting. Managerial accountants work together with purchasing and production schedulers in keeping the flow of materials accurate and efficient. This method was initiated by Toyota Motor Corporation, and it has expanded to many other manufacturing organizations throughout the world. Toyota set the example by controlling their inventory levels by relying on their supply chain to deliver the raw materials it needed to build their cars. The parts arrived just as they were needed, not before or after. One major advantage of JIT manufacturing is reducing costs by eradicating warehouse storage needs. Organizations, in turn, tend to spend less money on raw materials because of a reduction in spoilage and waste. Another advantage is that companies can easily move from the assembly of one product to the assembly of another. Disadvantages of JIT manufacturing start with its complexity. In moving from a traditional manufacturing approach to a JIT approach, management must reconfigure the entire flow of the production process, from the initial use of the raw materials to the output of the final finished good. Another disadvantage of JIT manufacturing is that it makes organizations more susceptible to disruptions in the supply chain. If a supplier of raw materials has a labor strike, weather problems, a breakdown of machinery, or some other catastrophe and cannot deliver the materials on time, that one supplier can shut down an entire production process and delay delivery of finished goods. An example of this occurred in 2011 after a tsunami and earthquake hit Japan and disrupted production at a critical supplier of auto parts. General Motors (GM) facilities in the United States announced they would have to shut down assembly plants where they could not continue production without the parts from Japan. Lean Six Sigma (LSS) is a quality control program that depends on a combined effort of many team members to enhance performance by analytically removing waste and diminishing variations between products. The lean component of LSS is the concept that anything that is not needed in a product or service, or any unnecessary steps that exist, add cost to the product or service and therefore should be considered waste and eliminated. The Six Sigma component of LSS has to do with the elimination of defects. Essentially, as a company becomes leaner, it should also be able to reduce defects in manufacturing or in providing a service. Fewer defects add to cost savings through the need for fewer reworked products, fewer repeat service calls, and therefore, more satisfied customers. It was developed by Motorola in 1986 and emphasized cycle-time improvement and the reduction of defects. This process has shown to be a powerful way of improving business efficiency and effectiveness. As organizations continue to modify and update their processes for optimal productivity, they must be flexible. As of 2017, LSS had developed into a business management way of thinking that focused on customer needs, customer retention, and improvement of business products and services. There are many establishments, including Motorola, that now do LSS training. There are certifications including white belt, yellow belt, green belt, black belt, and master black belt. The belts signify an employee’s knowledge regarding LSS. For example, a white belt understands the terminology, structure, and idea of LSS and reports issues to green or black belts. A green belt typically manages LSS projects, and a master black belt works with upper-level management to find the areas in the business where LSS needs to be implemented, leads several LSS teams, and oversees implementation of those projects. Kaizen (Japanese for change for the better ) is another process that is often linked to Six Sigma ( Figure 1.12 ). The two concepts are often used together for process improvements, as they both are designed for continuous improvement by eliminating waste and increasing efficiencies. The concept of kaizen comes from an ancient Japanese philosophy that involves continuously working toward perfection in all areas of one’s life. It was adopted in the business world after World War II in an effort to rebuild Japan. It centers on making small, day-to-day changes that develop into major improvements over time. The key behind the success of kaizen comes from requiring all employees—from the CEO at the top, all the way down to the shop-floor janitors—to participate by making recommendations to improve the organization. From the start of the process, it must be well defined that all recommendations are appreciated and that there will be no adverse results for participating. Workers, instead, should be rewarded for any modifications that advance the workplace. Employees become more self-assured and invested when they help improve the company. Another lean practice, the theory of constraints (TOC) , involves recognizing and removing bottlenecks within the value chain that may be limiting an organization’s profitability. This philosophy, developed by Dr. Eliyahu M. Goldratt, is a valuable instrument for improving the flaws in processes. The main goal of this methodology is to remove obstructions, or constraints, which are referred to as “bottlenecks.” There are several types of bottlenecks that organizations must deal with endlessly. One example occurs at the grocery store when it is crowded and there are only three checkout lanes open but ten people in each line. Obviously, the bottleneck is created by having too few checkout lanes open. The bottleneck can be mitigated by opening more checkout lanes. Other examples are listed in Table 1.5 . Examples of Constraints Bottleneck Examples Physical Employee resources, limited space, equipment resources Policy Procedures, regulations, contracts Culture “It’s the way we’ve always done it” Market Size of the market, demand for product, nature of competition Table 1.5 There are five steps in the cycle of continuous improvement under TOC: Identify the system constraint. Decide how best to exploit the constraint and make quick changes using existing resources. Subordinate everything else to the process to ensure alignment with and support of the needs of the constraint. Elevate the system’s constraint, and determine if the constraint has shifted to another area in the process. Repeat the process. This is a continuous cycle; therefore, once a bottleneck is solved, the next bottleneck should be addressed immediately ( Figure 1.13 ). Balanced Scorecard The balanced scorecard (BSC) approach uses both financial and nonfinancial measures in evaluating all attributes of the organization’s procedures. This approach differs from the traditional approach of only using financial measures to evaluate a company. While financial measures are essential, they are only a portion of what needs to be evaluated. The balanced scorecard focuses on both high-level and low-level measures, using the company’s own strategic plan. This method assesses the organization in four separate perspectives: Financial. The financial measures are the major focus of the BSC—but not the only measures. This perspective asks questions like whether the organization is making money or whether the stockholders are pleased. Customer. The BSC also evaluates how the organization is perceived, from the customer’s perspective. This measures customer satisfaction, new customer growth, and market share. Internal process. The internal procedures and processes perspective observes how smoothly things are running. This perspective will examine quality, efficiency, and waste as they relate directly to the products or services. Learning and growth/capacity. This area evaluates the entity and its performance from the standpoint of human capital, infrastructure, culture, technology, and other areas. Are employees collaborating and sharing information? Does everyone have access to the latest trends in training and continuing education in their areas? The main advantage of this approach is that it offers organizations a way to see the cause-and-effect in the objectives. For example, if an organization would like to make more money in order to pay higher dividends to its stockholders, the organization will need to increase market share, improve customer satisfaction, or grow its customer base. In order to make customers happier or gain new customers, the organization could try to reduce defects and increase overall quality of the products; to accomplish that, the organization could retrain or offer new training to its employees. Globalization The development of business through international influence or extending social and cultural aspects around the world is known as globalization . It has expanded our competitive borders, giving customers more alternatives. Customers can order an item from another country with the click of a button and have that item delivered in a few days or less. How has globalization affected companies? Not only must they choose between ordering goods or components globally, but they must decide in which countries to sell their goods, and in which companies they may be able to establish factories. Globalization affects management accountants in several ways. Companies need real-time, accurate information to make good decisions, so more timely and accurate information is needed. As companies expand globally, managers need to know the cost of operating internationally, as well as the laws, rules, and customs. Globalization also can expose companies to improvements in running a business. Debates continue as to the positive and negative consequences of globalization in all of its contexts. The advantages of globalization include helping developing countries in creating jobs, developing industries, differentiating and expanding their markets, and bettering their standard of living for their citizens. Some believe the expansion of pop culture around the globe to be an advantage of cultural globalization. It has multiplied the interchange of ideas, music, art, language, and cultural ideals. On the other side of the debate, one common criticism of globalization is that it has enhanced wealth disparity and, further, that organizations of the Western world have benefited much more than those anywhere else. There is also the argument that globalization is improving standards of living worldwide as industrialization is expanding, but it is causing global warming and climate change, due to the greenhouse gases the factories emit. Additionally, in some areas it has led to the abuse and misuse of natural resources and caused other detrimental consequences. How do these various globalization debates affect businesses? A successful company must be profitable to stay in business, but profitability is not the single key to success. A successful company must also consider the environment in which it operates—culturally, socially, environmentally, and economically—which requires companies to evolve and adjust as each of these environments changes. This evolution means that companies must continually evaluate themselves and their impact on all of their stakeholders, which include investors, creditors, management, employees, customers, governments, and, either directly or indirectly, the world. What companies used as measures of success forty years ago are different from the measures used twenty years ago, and those are different from those that are used today and still different from what will be needed in the future. Management accounting is the area in which many of these changing measures are either generated or evaluated. Such measures not only evaluate the cost effectiveness of products or services, but determine the best way to evaluate and reward employees and evaluate the cost-benefit of environmental protections, the impact of automation versus outsourcing, and the cost of training and educating employees. Ethical Considerations Global Ethics In an article in Business 2 Community , Kate Gerasimova draws on her experience within the Russian and American business environments to discuss the role of ethics in global business endeavors. Ethics are the principles, and the values that underlie them, that allow us to determine what is right and wrong. According to Gerasimova, ethics fall into three categories: “code and compliance, destiny and values, and social outreach.” 8 In the global business context, she also emphasizes the importance of respecting differences in values held by coworkers, communicating honestly in business dealings, and building trust. To assist in the application of the organization’s ethical approach to doing business in a different culture, it needs to develop a set of “core values as the basis for global policies and decision-making.” 9 Gerasimova notes that organizations also need to consider that “clients and coworkers may have a different perspective on ethics and proper behavior than those to which you are accustomed.” To address the different perspectives, an organization should train its employees to be culturally sensitive while balancing the need for rules and policies with the ability for employees to be flexible and to use their imagination. 8 Kate Gerasimova. “The Critical Role of Ethics and Culture in Business Globalization.” Business to Community . September 29, 2016. https://www.business2community.com/strategy/critical-role-ethics-culture-business-globalization-01667737 9 Kate Gerasimova. “The Critical Role of Ethics and Culture in Business Globalization.” Business to Community . September 29, 2016. https://www.business2community.com/strategy/critical-role-ethics-culture-business-globalization-01667737 Social Responsibility and Sustainability What is sustainability , and what does it have to do with businesses? The United Nations definition is “the ability to meet the needs of the present without compromising the ability of future generations to meet their own needs.” 10 Usually, sustainability is viewed as having three components: economic, social, and environmental. Obviously, a business cannot continue into the future unless it is economically sound; however, if it maintains its economic status by depleting too many natural resources or paying illegal wages, then that company is not practicing good social responsibility. 10 “Sustainable Development.” General Assembly of the United Nations. http://www.un.org/en/ga/president/65/issues/sustdev.shtml Corporate social responsibility (CSR) is an organization’s programs that evaluate and take responsibility for the organization’s effects on environmental and social welfare. There are many aspects of corporate social responsibility, including the types, locations, and wages of the labor employed; the ways in which renewable and nonrenewable resources are utilized; how charitable organizations or local areas in which the company operates are helped; and setting corporate employee policies such as maternity and paternity leave that promote family well-being. Although the causes and cures of climate change are open to discussion, most will agree that everyone, including corporations, should do their part to avoid further damage and improve any negative impact on the environment. Concepts In Practice Corporate Social Responsibility at New Belgium Brewing As New Belgium Brewing Company states on their website: “We’re New Belgium and we pollute. There. We said it. We are not perfect and we know it.” But New Belgium Brewing has become a leader in sustainability. They preach it in every aspect of the company: production, marketing, employees, and customers. The company makes the point that being energy efficient is not only being environmentally responsible, it is being financially responsible through their “internal energy efficiency tax.” The company uses many different metrics to track and improve its impact on the environment. For example, the company measures its energy usage and taxes itself on energy consumption and then saves those internal tax dollars to implement further energy savings by installing new processes and techniques. They divert 99.9 percent of the waste from their brewery away from landfills. The company makes enough in recycling revenues to pay four salaries. These are just a few ways in which New Belgium Brewing faces the challenges of social responsibility. Read more at http://www.newbelgium.com/Sustainability/Environmental-Metrics. In late 2016, the Paris Agreement (Paris Accord) brought together nations for the common cause of combatting climate change. There were 197 nations in attendance, and until recently, all 197 ratified or agreed to the effort. It requires all partners to pursue specific endeavors to keep the global temperature rise to 2 degrees Celsius above that of preindustrial levels. This would be accomplished by voluntarily reducing greenhouse gas emissions. In early 2017, US President Donald Trump announced that the United States would withdraw from the agreement. At that time, only Syria and Nicaragua were holdouts. Since then, both have signed the agreement, leaving the United States now as the lone holdout, although it will take several years for the formal withdrawal. In spite of the president’s announcement, there have been representatives from cities, states, corporations, and universities around the United States that have pledged to continue with the agreement and meet the greenhouse gas emission targets as set out in the Paris Accord. Many of the corporations who have promised to move forward with reducing greenhouse gases have expressed that the Paris Accord expands markets for groundbreaking clean technologies and that it creates employment opportunities alongside economic growth. In terms of managerial accounting, sustainable business practices create many issues. Organizations need to decide what elements will be measured. For example, minimizing electricity consumption, maximizing employee safety, or reducing greenhouse gases may be the biggest issue of concern for a company. Then, the company needs to determine ways of measurement that make sense regarding those items. Companies are becoming more aware of their impact on the world, and many are creating social responsibility reports in addition to their annual reports. This type of reporting requires different types of information and analysis than the typical financial measures gathered by companies. This is sometimes referred to as the triple bottom line , as it assesses an organization’s performance not only relating to the profit, but also relating to the world and its people, and will be covered in Sustainability Reporting . Your Turn Zaley’s Machining Division Zaley is an aerospace manufacturing firm in the southwest United States. They manufacture several products used in the aviation and aerospace industry. The company has been steadily growing over the past ten years in both sales and personnel. The engineering and design team uses computerized aided drafting (CAD) to design the various products that are produced by the machining division. The machining division recently implemented significant technological improvements by installing an advanced technique using hard-metal and aluminum high-speed machining. The following managers are involved with the machining division: Alex Freedman, technical specialist (supervises all computer programs) Emma Vlovski, sales manager (supervises all sales agents) Kayla McClaughley, cost accounting director (supervises all cost accountants) Mwangi Kori, lead test engineer (oversees all new-product testing and design) Torek Sanchez, production director (supervises all manufacturing employees) Each of these managers needs information to make decisions needed to carry out the respective jobs. Think about what might be involved in the job of each of these managers and the types of decisions they may be required to make in order to meet the goals of the company. What information would be needed by each of the managers? Solution Answers will vary. Sample answer: Alex Freeman, technical specialist (supervises all computer programs), needs information on the hours and type of usage possibly by department or by individual to ascertain if the equipment is being used effectively or if the programs used by the company are appropriate or additions or deletions need to be made. In addition, this information is needed to address how much and what type of staffing he needs in his department. Emma Vlovski, sales manager (supervises all sales agents), would want information about the level and type of sales for the company as a whole as well as for the individual sales agents. She would want to know which products are selling well, which ones are not, which sales agents are being the most successful, and why they are more successful than the others. Emma would also want information on how the agents are compensated, as this may be tied to the sales agent’s efforts to meet sales goals. Kayla McClaughley, cost accounting director (supervises all cost accountants), would want to know what tasks the cost accountants perform, how much time they spend on these tasks, and whether there are any redundancies in workload so that improvements in efficiency can be made. If any of the accountants has certifications such as CPA or CMA, she would want to know if they are keeping their certifications current through continuing professional education. Mwangi Kori, lead test engineer (oversees all new-product testing and design), would need information on the efficiency and effectiveness of each of the products tested, including success and failure rates. She would want information on how well the policies and procedures for design changes are being followed and if those policies and procedures need updating or rewriting. Thomas Sanchez, production director (supervises all manufacturing employees), would want information on hours worked, pay rates, and training (past and ongoing) for the manufacturing employees. She would also want information on how each individual employee performs his or her role in the manufacturing environment. For example, are there particular employees who have fewer defects or down time in their part of the process than others?
u.s._history
Summary 18.1 Inventors of the Age Inventors in the late nineteenth century flooded the market with new technological advances. Encouraged by Great Britain’s Industrial Revolution, and eager for economic development in the wake of the Civil War, business investors sought the latest ideas upon which they could capitalize, both to transform the nation as well as to make a personal profit. These inventions were a key piece of the massive shift towards industrialization that followed. For both families and businesses, these inventions eventually represented a fundamental change in their way of life. Although the technology spread slowly, it did spread across the country. Whether it was a company that could now produce ten times more products with new factories, or a household that could communicate with distant relations, the old way of doing things was disappearing. Communication technologies, electric power production, and steel production were perhaps the three most significant developments of the time. While the first two affected both personal lives and business development, the latter influenced business growth first and foremost, as the ability to produce large steel elements efficiently and cost-effectively led to permanently changes in the direction of industrial growth. 18.2 From Invention to Industrial Growth As the three tycoons profiled in this section illustrate, the end of the nineteenth century was a period in history that offered tremendous financial rewards to those who had the right combination of skill, ambition, and luck. Whether self-made millionaires like Carnegie or Rockefeller, or born to wealth like Morgan, these men were the lynchpins that turned inventors’ ideas into industrial growth. Steel production, in particular, but also oil refining techniques and countless other inventions, changed how industries in the country could operate, allowing them to grow in scale and scope like never before. It is also critical to note how these different men managed their businesses and ambition. Where Carnegie felt strongly that it was the job of the wealthy to give back in their lifetime to the greater community, his fellow tycoons did not necessarily agree. Although he contributed to many philanthropic efforts, Rockefeller’s financial success was built on the backs of ruined and bankrupt companies, and he came to be condemned by progressive reformers who questioned the impact on the working class as well as the dangers of consolidating too much power and wealth into one individual’s hands. Morgan sought wealth strictly through the investment in, and subsequent purchase of, others’ hard work. Along the way, the models of management they adopted—horizontal and vertical integration, trusts, holding companies, and investment brokerages—became commonplace in American businesses. Very quickly, large business enterprises fell under the control of fewer and fewer individuals and trusts. In sum, their ruthlessness, their ambition, their generosity, and their management made up the workings of America’s industrial age. 18.3 Building Industrial America on the Backs of Labor After the Civil War, as more and more people crowded into urban areas and joined the ranks of wage earners, the landscape of American labor changed. For the first time, the majority of workers were employed by others in factories and offices in the cities. Factory workers, in particular, suffered from the inequity of their positions. Owners had no legal restrictions on exploiting employees with long hours in dehumanizing and poorly paid work. Women and children were hired for the lowest possible wages, but even men’s wages were barely enough upon which to live. Poor working conditions, combined with few substantial options for relief, led workers to frustration and sporadic acts of protest and violence, acts that rarely, if ever, gained them any lasting, positive effects. Workers realized that change would require organization, and thus began early labor unions that sought to win rights for all workers through political advocacy and owner engagement. Groups like the National Labor Union and Knights of Labor both opened their membership to any and all wage earners, male or female, Black or White, regardless of skill. Their approach was a departure from the craft unions of the very early nineteenth century, which were unique to their individual industries. While these organizations gained members for a time, they both ultimately failed when public reaction to violent labor strikes turned opinion against them. The American Federation of Labor, a loose affiliation of different unions, grew in the wake of these universal organizations, although negative publicity impeded their work as well. In all, the century ended with the vast majority of American laborers unrepresented by any collective or union, leaving them vulnerable to the power wielded by factory ownership. 18.4 A New American Consumer Culture While tensions between owners and workers continued to grow, and wage earners struggled with the challenges of industrial work, the culture of American consumerism was changing. Greater choice, easier access, and improved goods at lower prices meant that even lower-income Americans, whether rural and shopping via mail order, or urban and shopping in large department stores, had more options. These increased options led to a rise in advertising, as businesses competed for customers. Furthermore, the opportunity to buy on credit meant that Americans could have their goods, even without ready cash. The result was a population that had a better standard of living than ever before, even as they went into debt or worked long factory hours to pay for it.
Chapter Outline 18.1 Inventors of the Age 18.2 From Invention to Industrial Growth 18.3 Building Industrial America on the Backs of Labor 18.4 A New American Consumer Culture Introduction “The electric age was ushered into being in this last decade of the nineteenth century today when President Cleveland, by pressing a button, started the mighty machinery, rushing waters and revolving wheels in the World’s Columbian exhibition.” With this announcement about the official start of the Chicago World’s Fair in 1893 ( Figure 18.1 ), the Salt Lake City Herald captured the excitement and optimism of the machine age. “In the previous expositions,” the editorial continued, “the possibilities of electricity had been limited to the mere starting of the engines in the machinery hall, but in this it made thousands of servants do its bidding . . . the magic of electricity did the duty of the hour.” The fair, which commemorated the four hundredth anniversary of Columbus’s journey to America, was a potent symbol of the myriad inventions that changed American life and contributed to the significant economic growth of the era, as well as the new wave of industrialization that swept the country. While businessmen capitalized upon such technological innovations, the new industrial working class faced enormous challenges. Ironically, as the World’s Fair welcomed its first visitors, the nation was spiraling downward into the worst depression of the century. Subsequent frustrations among working-class Americans laid the groundwork for the country’s first significant labor movement.
[ { "answer": { "ans_choice": 1, "ans_text": "B" }, "bloom": null, "hl_context": "<hl> In offices , worker productivity benefited from the typewriter , invented in 1867 , the cash register , invented in 1879 , and the adding machine , invented in 1885 . <hl> These tools made it easier than ever to keep up with the rapid pace of business growth . Inventions also slowly transformed home life . The vacuum cleaner arrived during this era , as well as the flush toilet . These indoor “ water closets ” improved public health through the reduction in contamination associated with outhouses and their proximity to water supplies and homes . <hl> Tin cans and , later , Clarence Birdseye ’ s experiments with frozen food , eventually changed how women shopped for , and prepared , food for their families , despite initial health concerns over preserved foods . <hl> With the advent of more easily prepared food , women gained valuable time in their daily schedules , a step that partially laid the groundwork for the modern women ’ s movement . Women who had the means to purchase such items could use their time to seek other employment outside of the home , as well as broaden their knowledge through education and reading . Such a transformation did not occur overnight , as these inventions also increased expectations for women to remain tied to the home and their domestic chores ; slowly , the culture of domesticity changed . <hl> From corrugated rollers that could crack hard , homestead-grown wheat into flour to refrigerated train cars and garment-sewing machines ( Figure 18.3 ) , new inventions fueled industrial growth around the country . <hl> As late as 1880 , fully one-half of all Americans still lived and worked on farms , whereas fewer than one in seven — mostly men , except for long-established textile factories in which female employees tended to dominate — were employed in factories . However , the development of commercial electricity by the close of the century , to complement the steam engines that already existed in many larger factories , permitted more industries to concentrate in cities , away from the previously essential water power . In turn , newly arrived immigrants sought employment in new urban factories . Immigration , urbanization , and industrialization coincided to transform the face of American society from primarily rural to significantly urban . From 1880 to 1920 , the number of industrial workers in the nation quadrupled from 2.5 million to over 10 million , while over the same period urban populations doubled , to reach one-half of the country ’ s total population .", "hl_sentences": "In offices , worker productivity benefited from the typewriter , invented in 1867 , the cash register , invented in 1879 , and the adding machine , invented in 1885 . Tin cans and , later , Clarence Birdseye ’ s experiments with frozen food , eventually changed how women shopped for , and prepared , food for their families , despite initial health concerns over preserved foods . From corrugated rollers that could crack hard , homestead-grown wheat into flour to refrigerated train cars and garment-sewing machines ( Figure 18.3 ) , new inventions fueled industrial growth around the country .", "question": { "cloze_format": "___ were not a successful invention of the era.", "normal_format": "Which of these was not a successful invention of the era?", "question_choices": [ "high-powered sewing machines", "movies with sound", "frozen foods", "typewriters" ], "question_id": "fs-idm54902432", "question_text": "Which of these was not a successful invention of the era?" }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 2, "ans_text": "It allowed machines to be farther from the power source. " }, "bloom": null, "hl_context": "In 1879 , Edison invented the item that has led to his greatest fame : the practical incandescent light bulb . He allegedly explored over six thousand different materials for the filament , before stumbling upon carbonized cotton thread as the ideal substance . By 1882 , with financial backing largely from financier J . P . Morgan , he had created the Edison Electric Illuminating Company , which began supplying electrical current to a small number of customers in New York City . Morgan guided subsequent mergers of Edison ’ s other enterprises , including a machine works firm and a lamp company , resulting in the creation of the Edison General Electric Company in 1889 . The next stage of invention in electric power came about with the contribution of George Westinghouse . <hl> Westinghouse was responsible for making electric lighting possible on a national scale . <hl> <hl> While Edison used “ direct current ” or DC power , which could only extend two miles from the power source , in 1886 , Westinghouse founded an electric company that promoted “ alternating current ” or AC power , which allowed for delivery over greater distances due to its wavelike patterns . <hl> The Westinghouse Electric Company delivered AC power , which meant that factories , homes , and farms — in short , anything that needed power — could be served , regardless of their proximity to the power source . A public relations battle ensued between the Westinghouse and Edison camps , coinciding with the invention of the electric chair as a form of prisoner execution . Edison publicly proclaimed AC power to be best adapted for use in the chair , in the hope that such a smear campaign would result in homeowners becoming reluctant to use AC power in their houses . Although Edison originally fought the use of AC power in other devices , he reluctantly adapted to it as its popularity increased . 18.2 From Invention to Industrial Growth Learning Objectives By the end of this section , you will be able to :", "hl_sentences": "Westinghouse was responsible for making electric lighting possible on a national scale . While Edison used “ direct current ” or DC power , which could only extend two miles from the power source , in 1886 , Westinghouse founded an electric company that promoted “ alternating current ” or AC power , which allowed for delivery over greater distances due to its wavelike patterns .", "question": { "cloze_format": "The major advantage of Westinghouse's \"alternating current\" power invention was ____.", "normal_format": "What was the major advantage of Westinghouse’s “alternating current” power invention?", "question_choices": [ "It was less prone to fire.", "It cost less to produce. ", "It allowed machines to be farther from the power source. ", "It was not under Edison’s control. " ], "question_id": "fs-idm33369600", "question_text": "What was the major advantage of Westinghouse’s “alternating current” power invention?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 0, "ans_text": "Jay Gould" }, "bloom": null, "hl_context": "<hl> Jay Gould was perhaps the first prominent railroad magnate to be tarred with the “ robber baron ” brush . <hl> <hl> He bought older , smaller , rundown railroads , offered minimal improvements , and then capitalized on factory owners ’ desires to ship their goods on this increasingly popular and more cost-efficient form of transportation . <hl> His work with the Erie Railroad was notorious among other investors , as he drove the company to near ruin in a failed attempt to attract foreign investors during a takeover attempt . His model worked better in the American West , where the railroads were still widely scattered across the country , forcing farmers and businesses to pay whatever prices Gould demanded in order to use his trains . In addition to owning the Union Pacific Railroad that helped to construct the original transcontinental railroad line , Gould came to control over ten thousand miles of track across the United States , accounting for 15 percent of all railroad transportation . When he died in 1892 , Gould had a personal worth of over $ 100 million , although he was a deeply unpopular figure .", "hl_sentences": "Jay Gould was perhaps the first prominent railroad magnate to be tarred with the “ robber baron ” brush . He bought older , smaller , rundown railroads , offered minimal improvements , and then capitalized on factory owners ’ desires to ship their goods on this increasingly popular and more cost-efficient form of transportation .", "question": { "cloze_format": "___ was a \"robber barons\" who was notable for the exploitative way he made his fortune in railroads.", "normal_format": "Which of the following “robber barons” was notable for the exploitative way he made his fortune in railroads?", "question_choices": [ "Jay Gould", "Cornelius Vanderbilt", "Andrew Carnegie", "J. Pierpont Morgan" ], "question_id": "fs-idp28818512", "question_text": "Which of the following “robber barons” was notable for the exploitative way he made his fortune in railroads?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 2, "ans_text": "C" }, "bloom": null, "hl_context": "In order to control the variety of interests he now maintained in industry , Rockefeller created a new legal entity , known as a trust . In this arrangement , a small group of trustees possess legal ownership of a business that they operate for the benefit of other investors . In 1882 , all thirty-seven stockholders in the various Standard Oil enterprises gave their stock to nine trustees who were to control and direct all of the company ’ s business ventures . State and federal challenges arose , due to the obvious appearance of a monopoly , which implied sole ownership of all enterprises composing an entire industry . <hl> When the Ohio Supreme Court ruled that the Standard Oil Company must dissolve , as its monopoly control over all refining operations in the U . S . was in violation of state and federal statutes , Rockefeller shifted to yet another legal entity , called a holding company model . <hl> The holding company model created a central corporate entity that controlled the operations of multiple companies by holding the majority of stock for each enterprise . While not technically a “ trust ” and therefore not vulnerable to anti-monopoly laws , this consolidation of power and wealth into one entity was on par with a monopoly ; thus , progressive reformers of the late nineteenth century considered holding companies to epitomize the dangers inherent in capitalistic big business , as can be seen in the political cartoon below ( Figure 18.9 ) . Impervious to reformers ’ misgivings , other businessmen followed Rockefeller ’ s example . By 1905 , over three hundred business mergers had occurred in the United States , affecting more than 80 percent of all industries . By that time , despite passage of federal legislation such as the Sherman Anti-Trust Act in 1890 , 1 percent of the country ’ s businesses controlled over 40 percent of the nation ’ s economy . Rockefeller was ruthless in his pursuit of total control of the oil refining business . As other entrepreneurs flooded the area seeking a quick fortune , Rockefeller developed a plan to crush his competitors and create a true monopoly in the refining industry . Beginning in 1872 , he forged agreements with several large railroad companies to obtain discounted freight rates for shipping his product . He also used the railroad companies to gather information on his competitors . As he could now deliver his kerosene at lower prices , he drove his competition out of business , often offering to buy them out for pennies on the dollar . <hl> He hounded those who refused to sell out to him , until they were driven out of business . <hl> <hl> Through his method of growth via mergers and acquisitions of similar companies — known as horizontal integration — Standard Oil grew to include almost all refineries in the area . <hl> By 1879 , the Standard Oil Company controlled nearly 95 percent of all oil refining businesses in the country , as well as 90 percent of all the refining businesses in the world . Editors of the New York World lamented of Standard Oil in 1880 that , “ When the nineteenth century shall have passed into history , the impartial eyes of the reviewers will be amazed to find that the U . S . . . . tolerated the presence of the most gigantic , the most cruel , impudent , pitiless and grasping monopoly that ever fastened itself upon a country . ” Seeking still more control , Rockefeller recognized the advantages of controlling the transportation of his product . <hl> He next began to grow his company through vertical integration , wherein a company handles all aspects of a product ’ s lifecycle , from the creation of raw materials through the production process to the delivery of the final product . <hl> In Rockefeller ’ s case , this model required investment and acquisition of companies involved in everything from barrel-making to pipelines , tanker cars to railroads . He came to own almost every type of business and used his vast power to drive competitors from the market through intense price wars . Although vilified by competitors who suffered from his takeovers and considered him to be no better than a robber baron , several observers lauded Rockefeller for his ingenuity in integrating the oil refining industry and , as a result , lowering kerosene prices by as much as 80 percent by the end of the century . Other industrialists quickly followed suit , including Gustavus Swift , who used vertical integration to dominate the U . S . meatpacking industry in the late nineteenth century . <hl> Social Darwinism added a layer of pseudoscience to the idea of the self-made man , a desirable thought for all who sought to follow Carnegie ’ s example . <hl> The myth of the rags-to-riches businessman was a potent one . Author Horatio Alger made his own fortune writing stories about young enterprising boys who beat poverty and succeeded in business through a combination of “ luck and pluck . ” His stories were immensely popular , even leading to a board game ( Figure 18.8 ) where players could hope to win in the same way that his heroes did .", "hl_sentences": "When the Ohio Supreme Court ruled that the Standard Oil Company must dissolve , as its monopoly control over all refining operations in the U . S . was in violation of state and federal statutes , Rockefeller shifted to yet another legal entity , called a holding company model . He hounded those who refused to sell out to him , until they were driven out of business . Through his method of growth via mergers and acquisitions of similar companies — known as horizontal integration — Standard Oil grew to include almost all refineries in the area . He next began to grow his company through vertical integration , wherein a company handles all aspects of a product ’ s lifecycle , from the creation of raw materials through the production process to the delivery of the final product . Social Darwinism added a layer of pseudoscience to the idea of the self-made man , a desirable thought for all who sought to follow Carnegie ’ s example .", "question": { "cloze_format": "____ does not represent one of the management strategies that John D. Rockefeller used in building his empire.", "normal_format": "Which of the following does not represent one of the management strategies that John D. Rockefeller used in building his empire?", "question_choices": [ "horizontal integration", "vertical integration", "social Darwinism", "the holding company model" ], "question_id": "fs-idm5904032", "question_text": "Which of the following does not represent one of the management strategies that John D. Rockefeller used in building his empire?" }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 2, "ans_text": "an eight-hour workday" }, "bloom": null, "hl_context": "<hl> Americana The Haymarket Rally On May 1 , 1886 , recognized internationally as a day for labor celebration , labor organizations around the country engaged in a national rally for the eight-hour workday . <hl> While the number of striking workers varied around the country , estimates are that between 300,000 and 500,000 workers protested in New York , Detroit , Chicago , and beyond . In Chicago , clashes between police and protesters led the police to fire into the crowd , resulting in fatalities . Afterward , angry at the deaths of the striking workers , organizers quickly organized a “ mass meeting , ” per the poster below ( Figure 18.13 ) .", "hl_sentences": "Americana The Haymarket Rally On May 1 , 1886 , recognized internationally as a day for labor celebration , labor organizations around the country engaged in a national rally for the eight-hour workday .", "question": { "cloze_format": "___ was one of the key goals for which striking workers fought in the late nineteenth century.", "normal_format": "What was one of the key goals for which striking workers fought in the late nineteenth century?", "question_choices": [ "health insurance", "disability pay", "an eight-hour workday", "women’s right to hold factory jobs" ], "question_id": "fs-idm25878320", "question_text": "What was one of the key goals for which striking workers fought in the late nineteenth century?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 1, "ans_text": "B" }, "bloom": null, "hl_context": "Although the NLU proved to be the wrong effort at the wrong time , in the wake of the Panic of 1873 and the subsequent frustration exhibited in the failed Molly Maguires uprising and the national railroad strike , another , more significant , labor organization emerged . <hl> The Knights of Labor ( KOL ) was more able to attract a sympathetic following than the Molly Maguires and others by widening its base and appealing to more members . <hl> Philadelphia tailor Uriah Stephens grew the KOL from a small presence during the Panic of 1873 to an organization of national importance by 1878 . <hl> That was the year the KOL held their first general assembly , where they adopted a broad reform platform , including a renewed call for an eight-hour workday , equal pay regardless of gender , the elimination of convict labor , and the creation of greater cooperative enterprises with worker ownership of businesses . <hl> Much of the KOL ’ s strength came from its concept of “ One Big Union ” — the idea that it welcomed all wage workers , regardless of occupation , with the exception of doctors , lawyers , and bankers . It welcomed women , African Americans , Native Americans , and immigrants , of all trades and skill levels . This was a notable break from the earlier tradition of craft unions , which were highly specialized and limited to a particular group . In 1879 , a new leader , Terence V . Powderly , joined the organization , and he gained even more followers due to his marketing and promotional efforts . Although largely opposed to strikes as effective tactics , through their sheer size , the Knights claimed victories in several railroad strikes in 1884 – 1885 , including one against notorious “ robber baron ” Jay Gould , and their popularity consequently rose among workers . By 1886 , the KOL had a membership in excess of 700,000 .", "hl_sentences": "The Knights of Labor ( KOL ) was more able to attract a sympathetic following than the Molly Maguires and others by widening its base and appealing to more members . That was the year the KOL held their first general assembly , where they adopted a broad reform platform , including a renewed call for an eight-hour workday , equal pay regardless of gender , the elimination of convict labor , and the creation of greater cooperative enterprises with worker ownership of businesses .", "question": { "cloze_format": "____ was not a key goal of the Knights of Labor.", "normal_format": "Which of the following was not a key goal of the Knights of Labor?", "question_choices": [ "an end to convict labor", "a graduated income tax on personal wealth", "equal pay regardless of gender", "the creation of cooperative business enterprises" ], "question_id": "fs-idm51584896", "question_text": "Which of the following was not a key goal of the Knights of Labor?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 2, "ans_text": "C" }, "bloom": null, "hl_context": "<hl> It may seem strange that , at a time when wages were so low , people began buying readily ; however , the slow emergence of a middle class by the end of the century , combined with the growing practice of buying on credit , presented more opportunities to take part in the new consumer culture . <hl> Stores allowed people to open accounts and purchase on credit , thus securing business and allowing consumers to buy without ready cash . Then , as today , the risks of buying on credit led many into debt . As advertising expert Roland Marchand described in his Parable on the Democracy of Goods , in an era when access to products became more important than access to the means of production , Americans quickly accepted the notion that they could live a better lifestyle by purchasing the right clothes , the best hair cream , and the shiniest shoes , regardless of their class . For better or worse , American consumerism had begun . The tremendous variety of goods available for sale required businesses to compete for customers in ways they had never before imagined . Suddenly , instead of a single option for clothing or shoes , customers were faced with dozens , whether ordered by mail , found at the local chain store , or lined up in massive rows at department stores . <hl> This new level of competition made advertising a vital component of all businesses . <hl> By 1900 , American businesses were spending almost $ 100 million annually on advertising . Competitors offered “ new and improved ” models as frequently as possible in order to generate interest . From toothpaste and mouthwash to books on entertaining guests , new goods were constantly offered . Newspapers accommodated the demand for advertising by shifting their production to include full-page advertisements , as opposed to the traditional column width , agate-type advertisements that dominated mid-nineteenth century newspapers ( similar to classified advertisements in today ’ s publications ) . Likewise , professional advertising agencies began to emerge in the 1880s , with experts in consumer demand bidding for accounts with major firms . Despite the challenges workers faced in their new roles as wage earners , the rise of industry in the United States allowed people to access and consume goods as never before . <hl> The rise of big business had turned America into a culture of consumers desperate for time-saving and leisure commodities , where people could expect to find everything they wanted in shops or by mail order . <hl> Gone were the days where the small general store was the only option for shoppers ; at the end of the nineteenth century , people could take a train to the city and shop in large department stores like Macy ’ s in New York , Gimbel ’ s in Philadelphia , and Marshall Field's in Chicago . Chain stores , like A & P and Woolworth ’ s , both of which opened in the 1870s , offered options to those who lived farther from major urban areas and clearly catered to classes other than the wealthy elite . Industrial advancements contributed to this proliferation , as new construction techniques permitted the building of stores with higher ceilings for larger displays , and the production of larger sheets of plate glass lent themselves to the development of larger store windows , glass countertops , and display cases where shoppers could observe a variety of goods at a glance . L . Frank Baum , of Wizard of Oz fame , later founded the National Association of Window Trimmers in 1898 , and began publishing The Store Window journal to advise businesses on space usage and promotion . Even families in rural America had new opportunities to purchase a greater variety of products than ever before , at ever decreasing prices . <hl> Those far from chain stores could benefit from the newly developed business of mail-order catalogs , placing orders by telephone . <hl> Aaron Montgomery Ward established the first significant mail-order business in 1872 , with Sears , Roebuck & Company following in 1886 . Sears distributed over 300,000 catalogs annually by 1897 , and later broke the one million annual mark in 1907 . Sears in particular understood that farmers and rural Americans sought alternatives to the higher prices and credit purchases they were forced to endure at small-town country stores . <hl> By clearly stating the prices in his catalog , Richard Sears steadily increased his company ’ s image of their catalog serving as “ the consumer ’ s bible . ” In the process , Sears , Roebuck & Company supplied much of America ’ s hinterland with products ranging from farm supplies to bicycles , toilet paper to automobiles , as seen below in a page from the catalog ( Figure 18.15 ) . <hl>", "hl_sentences": "It may seem strange that , at a time when wages were so low , people began buying readily ; however , the slow emergence of a middle class by the end of the century , combined with the growing practice of buying on credit , presented more opportunities to take part in the new consumer culture . This new level of competition made advertising a vital component of all businesses . The rise of big business had turned America into a culture of consumers desperate for time-saving and leisure commodities , where people could expect to find everything they wanted in shops or by mail order . Those far from chain stores could benefit from the newly developed business of mail-order catalogs , placing orders by telephone . By clearly stating the prices in his catalog , Richard Sears steadily increased his company ’ s image of their catalog serving as “ the consumer ’ s bible . ” In the process , Sears , Roebuck & Company supplied much of America ’ s hinterland with products ranging from farm supplies to bicycles , toilet paper to automobiles , as seen below in a page from the catalog ( Figure 18.15 ) .", "question": { "cloze_format": "____ did not contribute to the growth of a consumer culture in the United States at the close of the nineteenth century.", "normal_format": "Which of the following did not contribute to the growth of a consumer culture in the United States at the close of the nineteenth century?", "question_choices": [ "personal credit", "advertising", "greater disposable income", "mail-order catalogs" ], "question_id": "fs-idm60390320", "question_text": "Which of the following did not contribute to the growth of a consumer culture in the United States at the close of the nineteenth century?" }, "references_are_paraphrase": null } ]
18
18.1 Inventors of the Age Learning Objectives By the end of this section, you will be able to: Explain how the ideas and products of late nineteenth-century inventors contributed to the rise of big business Explain how the inventions of the late nineteenth century changed everyday American life The late nineteenth century was an energetic era of inventions and entrepreneurial spirit. Building upon the mid-century Industrial Revolution in Great Britain, as well as answering the increasing call from Americans for efficiency and comfort, the country found itself in the grip of invention fever, with more people working on their big ideas than ever before. In retrospect, harnessing the power of steam and then electricity in the nineteenth century vastly increased the power of man and machine, thus making other advances possible as the century progressed. Facing an increasingly complex everyday life, Americans sought the means by which to cope with it. Inventions often provided the answers, even as the inventors themselves remained largely unaware of the life-changing nature of their ideas. To understand the scope of this zeal for creation, consider the U.S. Patent Office, which, in 1790—its first decade of existence—recorded only 276 inventions. By 1860, the office had issued a total of 60,000 patents. But between 1860 and 1890, that number exploded to nearly 450,000, with another 235,000 in the last decade of the century. While many of these patents came to naught, some inventions became lynchpins in the rise of big business and the country’s move towards an industrial-based economy, in which the desire for efficiency, comfort, and abundance could be more fully realized by most Americans. AN EXPLOSION OF INVENTIVE ENERGY From corrugated rollers that could crack hard, homestead-grown wheat into flour to refrigerated train cars and garment-sewing machines ( Figure 18.3 ), new inventions fueled industrial growth around the country. As late as 1880, fully one-half of all Americans still lived and worked on farms, whereas fewer than one in seven—mostly men, except for long-established textile factories in which female employees tended to dominate—were employed in factories. However, the development of commercial electricity by the close of the century, to complement the steam engines that already existed in many larger factories, permitted more industries to concentrate in cities, away from the previously essential water power. In turn, newly arrived immigrants sought employment in new urban factories. Immigration, urbanization, and industrialization coincided to transform the face of American society from primarily rural to significantly urban. From 1880 to 1920, the number of industrial workers in the nation quadrupled from 2.5 million to over 10 million, while over the same period urban populations doubled, to reach one-half of the country’s total population. In offices, worker productivity benefited from the typewriter, invented in 1867, the cash register, invented in 1879, and the adding machine, invented in 1885. These tools made it easier than ever to keep up with the rapid pace of business growth. Inventions also slowly transformed home life. The vacuum cleaner arrived during this era, as well as the flush toilet. These indoor “water closets” improved public health through the reduction in contamination associated with outhouses and their proximity to water supplies and homes. Tin cans and, later, Clarence Birdseye’s experiments with frozen food, eventually changed how women shopped for, and prepared, food for their families, despite initial health concerns over preserved foods. With the advent of more easily prepared food, women gained valuable time in their daily schedules, a step that partially laid the groundwork for the modern women’s movement. Women who had the means to purchase such items could use their time to seek other employment outside of the home, as well as broaden their knowledge through education and reading. Such a transformation did not occur overnight, as these inventions also increased expectations for women to remain tied to the home and their domestic chores; slowly, the culture of domesticity changed. Perhaps the most important industrial advancement of the era came in the production of steel. Manufacturers and builders preferred steel to iron, due to its increased strength and durability. After the Civil War, two new processes allowed for the creation of furnaces large enough and hot enough to melt the wrought iron needed to produce large quantities of steel at increasingly cheaper prices. The Bessemer process, named for English inventor Henry Bessemer, and the open-hearth process, changed the way the United States produced steel and, in doing so, led the country into a new industrialized age. As the new material became more available, builders eagerly sought it out, a demand that steel mill owners were happy to supply. In 1860, the country produced thirteen thousand tons of steel. By 1879, American furnaces were producing over one million tons per year; by 1900, this figure had risen to ten million. Just ten years later, the United States was the top steel producer in the world, at over twenty-four million tons annually. As production increased to match the overwhelming demand, the price of steel dropped by over 80 percent. When quality steel became cheaper and more readily available, other industries relied upon it more heavily as a key to their growth and development, including construction and, later, the automotive industry. As a result, the steel industry rapidly became the cornerstone of the American economy, remaining the primary indicator of industrial growth and stability through the end of World War II. ALEXANDER GRAHAM BELL AND THE TELEPHONE Advancements in communications matched the pace of growth seen in industry and home life. Communication technologies were changing quickly, and they brought with them new ways for information to travel. In 1858, British and American crews laid the first transatlantic cable lines, enabling messages to pass between the United States and Europe in a matter of hours, rather than waiting the few weeks it could take for a letter to arrive by steamship. Although these initial cables worked for barely a month, they generated great interest in developing a more efficient telecommunications industry. Within twenty years, over 100,000 miles of cable crisscrossed the ocean floors, connecting all the continents. Domestically, Western Union, which controlled 80 percent of the country’s telegraph lines, operated nearly 200,000 miles of telegraph routes from coast to coast. In short, people were connected like never before, able to relay messages in minutes and hours rather than days and weeks. One of the greatest advancements was the telephone, which Alexander Graham Bell patented in 1876 ( Figure 18.4 ). While he was not the first to invent the concept, Bell was the first one to capitalize on it; after securing the patent, he worked with financiers and businessmen to create the National Bell Telephone Company. Western Union, which had originally turned down Bell’s machine, went on to commission Thomas Edison to invent an improved version of the telephone. It is actually Edison’s version that is most like the modern telephone used today. However, Western Union, fearing a costly legal battle they were likely to lose due to Bell’s patent, ultimately sold Edison’s idea to the Bell Company. With the communications industry now largely in their control, along with an agreement from the federal government to permit such control, the Bell Company was transformed into the American Telephone and Telegraph Company, which still exists today as AT&T. By 1880, fifty thousand telephones were in use in the United States, including one at the White House. By 1900, that number had increased to 1.35 million, and hundreds of American cities had obtained local service for their citizens. Quickly and inexorably, technology was bringing the country into closer contact, changing forever the rural isolation that had defined America since its beginnings. THOMAS EDISON AND ELECTRIC LIGHTING Although Thomas Alva Edison ( Figure 18.5 ) is best known for his contributions to the electrical industry, his experimentation went far beyond the light bulb. Edison was quite possibly the greatest inventor of the turn of the century, saying famously that he “hoped to have a minor invention every ten days and a big thing every month or so.” He registered 1,093 patents over his lifetime and ran a world-famous laboratory, Menlo Park, which housed a rotating group of up to twenty-five scientists from around the globe. Edison became interested in the telegraph industry as a boy, when he worked aboard trains selling candy and newspapers. He soon began tinkering with telegraph technology and, by 1876, had devoted himself full time to lab work as an inventor. He then proceeded to invent a string of items that are still used today: the phonograph, the mimeograph machine, the motion picture projector, the dictaphone, and the storage battery, all using a factory-oriented assembly line process that made the rapid production of inventions possible. In 1879, Edison invented the item that has led to his greatest fame: the practical incandescent light bulb. He allegedly explored over six thousand different materials for the filament, before stumbling upon carbonized cotton thread as the ideal substance. By 1882, with financial backing largely from financier J. P. Morgan, he had created the Edison Electric Illuminating Company, which began supplying electrical current to a small number of customers in New York City. Morgan guided subsequent mergers of Edison’s other enterprises, including a machine works firm and a lamp company, resulting in the creation of the Edison General Electric Company in 1889. The next stage of invention in electric power came about with the contribution of George Westinghouse. Westinghouse was responsible for making electric lighting possible on a national scale. While Edison used “direct current” or DC power, which could only extend two miles from the power source, in 1886, Westinghouse founded an electric company that promoted “alternating current” or AC power, which allowed for delivery over greater distances due to its wavelike patterns. The Westinghouse Electric Company delivered AC power, which meant that factories, homes, and farms—in short, anything that needed power—could be served, regardless of their proximity to the power source. A public relations battle ensued between the Westinghouse and Edison camps, coinciding with the invention of the electric chair as a form of prisoner execution. Edison publicly proclaimed AC power to be best adapted for use in the chair, in the hope that such a smear campaign would result in homeowners becoming reluctant to use AC power in their houses. Although Edison originally fought the use of AC power in other devices, he reluctantly adapted to it as its popularity increased. 18.2 From Invention to Industrial Growth Learning Objectives By the end of this section, you will be able to: Explain how the inventions of the late nineteenth century contributed directly to industrial growth in America Identify the contributions of Andrew Carnegie, John Rockefeller, and J. P. Morgan to the new industrial order emerging in the late nineteenth century Describe the visions, philosophies, and business methods of the leaders of the new industrial order As discussed previously, new processes in steel refining, along with inventions in the fields of communications and electricity, transformed the business landscape of the nineteenth century. The exploitation of these new technologies provided opportunities for tremendous growth, and business entrepreneurs with financial backing and the right mix of business acumen and ambition could make their fortunes. Some of these new millionaires were known in their day as robber barons , a negative term that connoted the belief that they exploited workers and bent laws to succeed. Regardless of how they were perceived, these businessmen and the companies they created revolutionized American industry. RAILROADS AND ROBBER BARONS Earlier in the nineteenth century, the first transcontinental railroad and subsequent spur lines paved the way for rapid and explosive railway growth, as well as stimulated growth in the iron, wood, coal, and other related industries. The railroad industry quickly became the nation’s first “big business.” A powerful, inexpensive, and consistent form of transportation, railroads accelerated the development of virtually every other industry in the country. By 1890, railroad lines covered nearly every corner of the United States, bringing raw materials to industrial factories and finished goods to consumer markets. The amount of track grew from 35,000 miles at the end of the Civil War to over 200,000 miles by the close of the century. Inventions such as car couplers, air brakes, and Pullman passenger cars allowed the volume of both freight and people to increase steadily. From 1877 to 1890, both the amount of goods and the number of passengers traveling the rails tripled. Financing for all of this growth came through a combination of private capital and government loans and grants. Federal and state loans of cash and land grants totaled $150 million and 185 million acres of public land, respectively. Railroads also listed their stocks and bonds on the New York Stock Exchange to attract investors from both within the United States and Europe. Individual investors consolidated their power as railroads merged and companies grew in size and power. These individuals became some of the wealthiest Americans the country had ever known. Midwest farmers, angry at large railroad owners for their exploitative business practices, came to refer to them as “robber barons,” as their business dealings were frequently shady and exploitative. Among their highly questionable tactics was the practice of differential shipping rates, in which larger business enterprises received discounted rates to transport their goods, as opposed to local producers and farmers whose higher rates essentially subsidized the discounts. Jay Gould was perhaps the first prominent railroad magnate to be tarred with the “robber baron” brush. He bought older, smaller, rundown railroads, offered minimal improvements, and then capitalized on factory owners’ desires to ship their goods on this increasingly popular and more cost-efficient form of transportation. His work with the Erie Railroad was notorious among other investors, as he drove the company to near ruin in a failed attempt to attract foreign investors during a takeover attempt. His model worked better in the American West, where the railroads were still widely scattered across the country, forcing farmers and businesses to pay whatever prices Gould demanded in order to use his trains. In addition to owning the Union Pacific Railroad that helped to construct the original transcontinental railroad line, Gould came to control over ten thousand miles of track across the United States, accounting for 15 percent of all railroad transportation. When he died in 1892, Gould had a personal worth of over $100 million, although he was a deeply unpopular figure. In contrast to Gould’s exploitative business model, which focused on financial profit more than on tangible industrial contributions, Commodore Cornelius Vanderbilt was a “robber baron” who truly cared about the success of his railroad enterprise and its positive impact on the American economy. Vanderbilt consolidated several smaller railroad lines, called trunk lines, to create the powerful New York Central Railroad Company, one of the largest corporations in the United States at the time ( Figure 18.6 ). He later purchased stock in the major rail lines that would connect his company to Chicago, thus expanding his reach and power while simultaneously creating a railroad network to connect Chicago to New York City. This consolidation provided more efficient connections from Midwestern suppliers to eastern markets. It was through such consolidation that, by 1900, seven major railroad tycoons controlled over 70 percent of all operating lines. Vanderbilt’s personal wealth at his death (over $100 million in 1877), placed him among the top three wealthiest individuals in American history. GIANTS OF WEALTH: CARNEGIE, ROCKEFELLER, AND MORGAN The post-Civil War inventors generated ideas that transformed the economy, but they were not big businessmen. The evolution from technical innovation to massive industry took place at the hands of the entrepreneurs whose business gambles paid off, making them some of the richest Americans of their day. Steel magnate Andrew Carnegie, oil tycoon John D. Rockefeller, and business financier J. P. Morgan were all businessmen who grew their respective businesses to a scale and scope that were unprecedented. Their companies changed how Americans lived and worked, and they themselves greatly influenced the growth of the country. Andrew Carnegie and The Gospel of Wealth Andrew Carnegie, steel magnate, has the prototypical rags-to-riches story. Although such stories resembled more myth than reality, they served to encourage many Americans to seek similar paths to fame and fortune. In Carnegie, the story was one of few derived from fact. Born in Scotland, Carnegie immigrated with his family to Pennsylvania in 1848. Following a brief stint as a “bobbin boy,” changing spools of thread at a Pittsburgh clothing manufacturer at age thirteen, he subsequently became a telegram messenger boy. As a messenger, he spent much of his time around the Pennsylvania Railroad office and developed parallel interests in railroads, bridge building, and, eventually, the steel industry. Ingratiating himself to his supervisor and future president of the Pennsylvania Railroad, Tom Scott, Carnegie worked his way into a position of management for the company and subsequently began to invest some of his earnings, with Scott’s guidance. One particular investment, in the booming oil fields of northwest Pennsylvania in 1864, resulted in Carnegie earning over $1 million in cash dividends, thus providing him with the capital necessary to pursue his ambition to modernize the iron and steel industries, transforming the United States in the process. Having seen firsthand during the Civil War, when he served as Superintendent of Military Railways and telegraph coordinator for the Union forces, the importance of industry, particularly steel, to the future growth of the country, Carnegie was convinced of his strategy. His first company was the J. Edgar Thompson Steel Works, and, a decade later, he bought out the newly built Homestead Steel Works from the Pittsburgh Bessemer Steel Company. By the end of the century, his enterprise was running an annual profit in excess of $40 million ( Figure 18.7 ). Although not a scientific expert in steel, Carnegie was an excellent promoter and salesman, able to locate financial backing for his enterprise. He was also shrewd in his calculations on consolidation and expansion, and was able to capitalize on smart business decisions. Always thrifty with the profits he earned, a trait owed to his upbringing, Carnegie saved his profits during prosperous times and used them to buy out other steel companies at low prices during the economic recessions of the 1870s and 1890s. He insisted on up-to-date machinery and equipment, and urged the men who worked at and managed his steel mills to constantly think of innovative ways to increase production and reduce cost. Carnegie, more than any other businessman of the era, championed the idea that America’s leading tycoons owed a debt to society. He believed that, given the circumstances of their successes, they should serve as benefactors to the less fortunate public. For Carnegie, poverty was not an abstract concept, as his family had been a part of the struggling masses. He desired to set an example of philanthropy for all other prominent industrialists of the era to follow. Carnegie’s famous essay, The Gospel of Wealth , featured below, expounded on his beliefs. In it, he borrowed from Herbert Spencer’s theory of social Darwinism , which held that society developed much like plant or animal life through a process of evolution in which the most fit and capable enjoyed the greatest material and social success. My Story Andrew Carnegie on Wealth Carnegie applauded American capitalism for creating a society where, through hard work, ingenuity, and a bit of luck, someone like himself could amass a fortune. In return for that opportunity, Carnegie wrote that the wealthy should find proper uses for their wealth by funding hospitals, libraries, colleges, the arts, and more. The Gospel of Wealth spelled out that responsibility. Poor and restricted are our opportunities in this life; narrow our horizon; our best work most imperfect; but rich men should be thankful for one inestimable boon. They have it in their power during their lives to busy themselves in organizing benefactions from which the masses of their fellows will derive lasting advantage, and thus dignify their own lives. . . . This, then, is held to be the duty of the man of Wealth: First, to set an example of modest, unostentatious living, shunning display or extravagance; to provide moderately for the legitimate wants of those dependent upon him; and after doing so to consider all surplus revenues which come to him simply as trust funds, which he is called upon to administer, and strictly bound as a matter of duty to administer in the manner which, in his judgment, is best calculated to produce the most beneficial results for the community—the man of wealth thus becoming the mere agent and trustee for his poorer brethren, bringing to their service his superior wisdom, experience and ability to administer, doing for them better than they would or could do for themselves. . . . In bestowing charity, the main consideration should be to help those who will help themselves; to provide part of the means by which those who desire to improve may do so; to give those who desire to use the aids by which they may rise; to assist, but rarely or never to do all. Neither the individual nor the race is improved by alms-giving. Those worthy of assistance, except in rare cases, seldom require assistance. The really valuable men of the race never do, except in cases of accident or sudden change. Every one has, of course, cases of individuals brought to his own knowledge where temporary assistance can do genuine good, and these he will not overlook. But the amount which can be wisely given by the individual for individuals is necessarily limited by his lack of knowledge of the circumstances connected with each. He is the only true reformer who is as careful and as anxious not to aid the unworthy as he is to aid the worthy, and, perhaps, even more so, for in alms-giving more injury is probably done by rewarding vice than by relieving virtue. —Andrew Carnegie, The Gospel of Wealth Social Darwinism added a layer of pseudoscience to the idea of the self-made man, a desirable thought for all who sought to follow Carnegie’s example. The myth of the rags-to-riches businessman was a potent one. Author Horatio Alger made his own fortune writing stories about young enterprising boys who beat poverty and succeeded in business through a combination of “luck and pluck.” His stories were immensely popular, even leading to a board game ( Figure 18.8 ) where players could hope to win in the same way that his heroes did. John D. Rockefeller and Business Integration Models Like Carnegie, John D. Rockefeller was born in 1839 of modest means, with a frequently absent traveling salesman of a father who sold medicinal elixirs and other wares. Young Rockefeller helped his mother with various chores and earned extra money for the family through the sale of family farm products. When the family moved to a suburb of Cleveland in 1853, he had an opportunity to take accounting and bookkeeping courses while in high school and developed a career interest in business. While living in Cleveland in 1859, he learned of Colonel Edwin Drake who had struck “black gold,” or oil, near Titusville, Pennsylvania, setting off a boom even greater than the California Gold Rush of the previous decade. Many sought to find a fortune through risky and chaotic “wildcatting,” or drilling exploratory oil wells, hoping to strike it rich. But Rockefeller chose a more certain investment: refining crude oil into kerosene, which could be used for both heating and lamps. As a more efficient source of energy, as well as less dangerous to produce, kerosene quickly replaced whale oil in many businesses and homes. Rockefeller worked initially with family and friends in the refining business located in the Cleveland area, but by 1870, Rockefeller ventured out on his own, consolidating his resources and creating the Standard Oil Company of Ohio, initially valued at $1 million. Rockefeller was ruthless in his pursuit of total control of the oil refining business. As other entrepreneurs flooded the area seeking a quick fortune, Rockefeller developed a plan to crush his competitors and create a true monopoly in the refining industry. Beginning in 1872, he forged agreements with several large railroad companies to obtain discounted freight rates for shipping his product. He also used the railroad companies to gather information on his competitors. As he could now deliver his kerosene at lower prices, he drove his competition out of business, often offering to buy them out for pennies on the dollar. He hounded those who refused to sell out to him, until they were driven out of business. Through his method of growth via mergers and acquisitions of similar companies—known as horizontal integration —Standard Oil grew to include almost all refineries in the area. By 1879, the Standard Oil Company controlled nearly 95 percent of all oil refining businesses in the country, as well as 90 percent of all the refining businesses in the world. Editors of the New York World lamented of Standard Oil in 1880 that, “When the nineteenth century shall have passed into history, the impartial eyes of the reviewers will be amazed to find that the U.S. . . . tolerated the presence of the most gigantic, the most cruel, impudent, pitiless and grasping monopoly that ever fastened itself upon a country.” Seeking still more control, Rockefeller recognized the advantages of controlling the transportation of his product. He next began to grow his company through vertical integration , wherein a company handles all aspects of a product’s lifecycle, from the creation of raw materials through the production process to the delivery of the final product. In Rockefeller’s case, this model required investment and acquisition of companies involved in everything from barrel-making to pipelines, tanker cars to railroads. He came to own almost every type of business and used his vast power to drive competitors from the market through intense price wars. Although vilified by competitors who suffered from his takeovers and considered him to be no better than a robber baron, several observers lauded Rockefeller for his ingenuity in integrating the oil refining industry and, as a result, lowering kerosene prices by as much as 80 percent by the end of the century. Other industrialists quickly followed suit, including Gustavus Swift, who used vertical integration to dominate the U.S. meatpacking industry in the late nineteenth century. In order to control the variety of interests he now maintained in industry, Rockefeller created a new legal entity, known as a trust . In this arrangement, a small group of trustees possess legal ownership of a business that they operate for the benefit of other investors. In 1882, all thirty-seven stockholders in the various Standard Oil enterprises gave their stock to nine trustees who were to control and direct all of the company’s business ventures. State and federal challenges arose, due to the obvious appearance of a monopoly, which implied sole ownership of all enterprises composing an entire industry. When the Ohio Supreme Court ruled that the Standard Oil Company must dissolve, as its monopoly control over all refining operations in the U.S. was in violation of state and federal statutes, Rockefeller shifted to yet another legal entity, called a holding company model. The holding company model created a central corporate entity that controlled the operations of multiple companies by holding the majority of stock for each enterprise. While not technically a “trust” and therefore not vulnerable to anti-monopoly laws, this consolidation of power and wealth into one entity was on par with a monopoly; thus, progressive reformers of the late nineteenth century considered holding companies to epitomize the dangers inherent in capitalistic big business, as can be seen in the political cartoon below ( Figure 18.9 ). Impervious to reformers’ misgivings, other businessmen followed Rockefeller’s example. By 1905, over three hundred business mergers had occurred in the United States, affecting more than 80 percent of all industries. By that time, despite passage of federal legislation such as the Sherman Anti-Trust Act in 1890, 1 percent of the country’s businesses controlled over 40 percent of the nation’s economy. J. Pierpont Morgan Unlike Carnegie and Rockefeller, J. P. Morgan was no rags-to-riches hero. He was born to wealth and became much wealthier as an investment banker, making wise financial decisions in support of the hard-working entrepreneurs building their fortunes. Morgan’s father was a London banker, and Morgan the son moved to New York in 1857 to look after the family’s business interests there. Once in America, he separated from the London bank and created the J. Pierpont Morgan and Company financial firm. The firm bought and sold stock in growing companies, investing the family’s wealth in those that showed great promise, turning an enormous profit as a result. Investments from firms such as his were the key to the success stories of up-and-coming businessmen like Carnegie and Rockefeller. In return for his investment, Morgan and other investment bankers demanded seats on the companies’ boards, which gave them even greater control over policies and decisions than just investment alone. There were many critics of Morgan and these other bankers, particularly among members of a U.S. congressional subcommittee who investigated the control that financiers maintained over key industries in the country. The subcommittee referred to Morgan’s enterprise as a form of “money trust” that was even more powerful than the trusts operated by Rockefeller and others. Morgan argued that his firm, and others like it, brought stability and organization to a hypercompetitive capitalist economy, and likened his role to a kind of public service. Ultimately, Morgan’s most notable investment, and greatest consolidation, was in the steel industry, when he bought out Andrew Carnegie in 1901. Initially, Carnegie was reluctant to sell, but after repeated badgering by Morgan, Carnegie named his price: an outrageously inflated sum of $500 million. Morgan agreed without hesitation, and then consolidated Carnegie’s holdings with several smaller steel firms to create the U.S. Steel Corporation. U.S. Steel was subsequently capitalized at $1.4 billion. It was the country’s first billion-dollar firm. Lauded by admirers for the efficiency and modernization he brought to investment banking practices, as well as for his philanthropy and support of the arts, Morgan was also criticized by reformers who subsequently blamed his (and other bankers’) efforts for contributing to the artificial bubble of prosperity that eventually burst in the Great Depression of the 1930s. What none could doubt was that Morgan’s financial aptitude and savvy business dealings kept him in good stead. A subsequent U.S. congressional committee, in 1912, reported that his firm held 341 directorships in 112 corporations that controlled over $22 billion in assets. In comparison, that amount of wealth was greater than the assessed value of all the land in the United States west of the Mississippi River. 18.3 Building Industrial America on the Backs of Labor Learning Objectives By the end of this section, you will be able to: Explain the qualities of industrial working-class life in the late nineteenth century Analyze both workers’ desire for labor unions and the reasons for unions’ inability to achieve their goals The growth of the American economy in the last half of the nineteenth century presented a paradox. The standard of living for many American workers increased. As Carnegie said in The Gospel of Wealth , “the poor enjoy what the rich could not before afford. What were the luxuries have become the necessaries of life. The laborer has now more comforts than the landlord had a few generations ago.” In many ways, Carnegie was correct. The decline in prices and the cost of living meant that the industrial era offered many Americans relatively better lives in 1900 than they had only decades before. For some Americans, there were also increased opportunities for upward mobility. For the multitudes in the working class, however, conditions in the factories and at home remained deplorable. The difficulties they faced led many workers to question an industrial order in which a handful of wealthy Americans built their fortunes on the backs of workers. WORKING-CLASS LIFE Between the end of the Civil War and the turn of the century, the American workforce underwent a transformative shift. In 1865, nearly 60 percent of Americans still lived and worked on farms; by the early 1900s, that number had reversed itself, and only 40 percent still lived in rural areas, with the remainder living and working in urban and early suburban areas. A significant number of these urban and suburban dwellers earned their wages in factories. Advances in farm machinery allowed for greater production with less manual labor, thus leading many Americans to seek job opportunities in the burgeoning factories in the cities. Not surprisingly, there was a concurrent trend of a decrease in American workers being self-employed and an increase of those working for others and being dependent on a factory wage system for their living. Yet factory wages were, for the most part, very low. In 1900, the average factory wage was approximately twenty cents per hour, for an annual salary of barely six hundred dollars. According to some historical estimates, that wage left approximately 20 percent of the population in industrialized cities at, or below, the poverty level. An average factory work week was sixty hours, ten hours per day, six days per week, although in steel mills, the workers put in twelve hours per day, seven days a week. Factory owners had little concern for workers’ safety. According to one of the few available accurate measures, as late as 1913, nearly 25,000 Americans lost their lives on the job, while another 700,000 workers suffered from injuries that resulted in at least one missed month of work. Another element of hardship for workers was the increasingly dehumanizing nature of their work. Factory workers executed repetitive tasks throughout the long hours of their shifts, seldom interacting with coworkers or supervisors. This solitary and repetitive work style was a difficult adjustment for those used to more collaborative and skill-based work, whether on farms or in crafts shops. Managers embraced Fredrick Taylor’s principles of scientific management , also called “stop-watch management,” where he used stop-watch studies to divide manufacturing tasks into short, repetitive segments. A mechanical engineer by training, Taylor encouraged factory owners to seek efficiency and profitability over any benefits of personal interaction. Owners adopted this model, effectively making workers cogs in a well-oiled machine. One result of the new breakdown of work processes was that factory owners were able to hire women and children to perform many of the tasks. From 1870 through 1900, the number of women working outside the home tripled. By the end of this period, five million American women were wage earners, with one-quarter of them working factory jobs. Most were young, under twenty-five, and either immigrants themselves or the daughters of immigrants. Their foray into the working world was not seen as a step towards empowerment or equality, but rather a hardship born of financial necessity. Women’s factory work tended to be in clothing or textile factories, where their appearance was less offensive to men who felt that heavy industry was their purview. Other women in the workforce worked in clerical positions as bookkeepers and secretaries, and as salesclerks. Not surprisingly, women were paid less than men, under the pretense that they should be under the care of a man and did not require a living wage. Factory owners used the same rationale for the exceedingly low wages they paid to children. Children were small enough to fit easily among the machines and could be hired for simple work for a fraction of an adult man’s pay. The image below ( Figure 18.10 ) shows children working the night shift in a glass factory. From 1870 through 1900, child labor in factories tripled. Growing concerns among progressive reformers over the safety of women and children in the workplace would eventually result in the development of political lobby groups. Several states passed legislative efforts to ensure a safe workplace, and the lobby groups pressured Congress to pass protective legislation. However, such legislation would not be forthcoming until well into the twentieth century. In the meantime, many working-class immigrants still desired the additional wages that child and women labor produced, regardless of the harsh working conditions. WORKER PROTESTS AND VIOLENCE Workers were well aware of the vast discrepancy between their lives and the wealth of the factory owners. Lacking the assets and legal protection needed to organize, and deeply frustrated, some working communities erupted in spontaneous violence. The coal mines of eastern Pennsylvania and the railroad yards of western Pennsylvania, central to both respective industries and home to large, immigrant, working enclaves, saw the brunt of these outbursts. The combination of violence, along with several other factors, blunted any significant efforts to organize workers until well into the twentieth century. Business owners viewed organization efforts with great mistrust, capitalizing upon widespread anti-union sentiment among the general public to crush unions through open shops, the use of strikebreakers, yellow-dog contracts (in which the employee agrees to not join a union as a pre-condition of employment), and other means. Workers also faced obstacles to organization associated with race and ethnicity, as questions arose on how to address the increasing number of low-paid African American workers, in addition to the language and cultural barriers introduced by the large wave of southeastern European immigration to the United States. But in large part, the greatest obstacle to effective unionization was the general public’s continued belief in a strong work ethic and that an individual work ethic—not organizing into radical collectives—would reap its own rewards. As violence erupted, such events seemed only to confirm widespread popular sentiment that radical, un-American elements were behind all union efforts. In the 1870s, Irish coal miners in eastern Pennsylvania formed a secret organization known as the Molly Maguires , named for the famous Irish patriot. Through a series of scare tactics that included kidnappings, beatings, and even murder, the Molly Maguires sought to bring attention to the miners’ plight, as well as to cause enough damage and concern to the mine owners that the owners would pay attention to their concerns. Owners paid attention, but not in the way that the protesters had hoped. They hired detectives to pose as miners and mingle among the workers to obtain the names of the Molly Maguires. By 1875, they had acquired the names of twenty-four suspected Maguires, who were subsequently convicted of murder and violence against property. All were convicted and ten were hanged in 1876, at a public “Day of the Rope.” This harsh reprisal quickly crushed the remaining Molly Maguires movement. The only substantial gain the workers had from this episode was the knowledge that, lacking labor organization, sporadic violent protest would be met by escalated violence. Public opinion was not sympathetic towards labor’s violent methods as displayed by the Molly Maguires. But the public was further shocked by some of the harsh practices employed by government agents to crush the labor movement, as seen the following year in the Great Railroad Strike of 1877. After incurring a significant pay cut earlier that year, railroad workers in West Virginia spontaneously went on strike and blocked the tracks ( Figure 18.11 ). As word spread of the event, railroad workers across the country joined in sympathy, leaving their jobs and committing acts of vandalism to show their frustration with the ownership. Local citizens, who in many instances were relatives and friends, were largely sympathetic to the railroad workers’ demands. The most significant violent outbreak of the railroad strike occurred in Pittsburgh, beginning on July 19. The governor ordered militiamen from Philadelphia to the Pittsburgh roundhouse to protect railroad property. The militia opened fire to disperse the angry crowd and killed twenty individuals while wounding another twenty-nine. A riot erupted, resulting in twenty-four hours of looting, violence, fire, and mayhem, and did not die down until the rioters wore out in the hot summer weather. In a subsequent skirmish with strikers while trying to escape the roundhouse, militiamen killed another twenty individuals. Violence erupted in Maryland and Illinois as well, and President Hayes eventually sent federal troops into major cities to restore order. This move, along with the impending return of cooler weather that brought with it the need for food and fuel, resulted in striking workers nationwide returning to the railroad. The strike had lasted for forty-five days, and they had gained nothing but a reputation for violence and aggression that left the public less sympathetic than ever. Dissatisfied laborers began to realize that there would be no substantial improvement in their quality of life until they found a way to better organize themselves. WORKER ORGANIZATION AND THE STRUGGLES OF UNIONS Prior to the Civil War, there were limited efforts to create an organized labor movement on any large scale. With the majority of workers in the country working independently in rural settings, the idea of organized labor was not largely understood. But, as economic conditions changed, people became more aware of the inequities facing factory wage workers. By the early 1880s, even farmers began to fully recognize the strength of unity behind a common cause. Models of Organizing: The Knights of Labor and American Federation of Labor In 1866, seventy-seven delegates representing a variety of different occupations met in Baltimore to form the National Labor Union (NLU). The NLU had ambitious ideas about equal rights for African Americans and women, currency reform, and a legally mandated eight-hour workday. The organization was successful in convincing Congress to adopt the eight-hour workday for federal employees, but their reach did not progress much further. The Panic of 1873 and the economic recession that followed as a result of overspeculation on railroads and the subsequent closing of several banks—during which workers actively sought any employment regardless of the conditions or wages—as well as the death of the NLU’s founder, led to a decline in their efforts. A combination of factors contributed to the debilitating Panic of 1873, which triggered what the public referred to at the time as the “Great Depression” of the 1870s. Most notably, the railroad boom that had occurred from 1840 to 1870 was rapidly coming to a close. Overinvestment in the industry had extended many investors’ capital resources in the form of railroad bonds. However, when several economic developments in Europe affected the value of silver in America, which in turn led to a de facto gold standard that shrunk the U.S. monetary supply, the amount of cash capital available for railroad investments rapidly declined. Several large business enterprises were left holding their wealth in all but worthless railroad bonds. When Jay Cooke & Company, a leader in the American banking industry, declared bankruptcy on the eve of their plans to finance the construction of a new transcontinental railroad, the panic truly began. A chain reaction of bank failures culminated with the New York Stock Exchange suspending all trading for ten days at the end of September 1873. Within a year, over one hundred railroad enterprises had failed; within two years, nearly twenty thousand businesses had failed. The loss of jobs and wages sent workers throughout the United States seeking solutions and clamoring for scapegoats. Although the NLU proved to be the wrong effort at the wrong time, in the wake of the Panic of 1873 and the subsequent frustration exhibited in the failed Molly Maguires uprising and the national railroad strike, another, more significant, labor organization emerged. The Knights of Labor (KOL) was more able to attract a sympathetic following than the Molly Maguires and others by widening its base and appealing to more members. Philadelphia tailor Uriah Stephens grew the KOL from a small presence during the Panic of 1873 to an organization of national importance by 1878. That was the year the KOL held their first general assembly, where they adopted a broad reform platform, including a renewed call for an eight-hour workday, equal pay regardless of gender, the elimination of convict labor, and the creation of greater cooperative enterprises with worker ownership of businesses. Much of the KOL’s strength came from its concept of “One Big Union”—the idea that it welcomed all wage workers, regardless of occupation, with the exception of doctors, lawyers, and bankers. It welcomed women, African Americans, Native Americans, and immigrants, of all trades and skill levels. This was a notable break from the earlier tradition of craft unions, which were highly specialized and limited to a particular group. In 1879, a new leader, Terence V. Powderly, joined the organization, and he gained even more followers due to his marketing and promotional efforts. Although largely opposed to strikes as effective tactics, through their sheer size, the Knights claimed victories in several railroad strikes in 1884–1885, including one against notorious “robber baron” Jay Gould, and their popularity consequently rose among workers. By 1886, the KOL had a membership in excess of 700,000. In one night, however, the KOL’s popularity—and indeed the momentum of the labor movement as a whole—plummeted due to an event known as the Haymarket affair , which occurred on May 4, 1886, in Chicago’s Haymarket Square ( Figure 18.12 ). There, an anarchist group had gathered in response to a death at an earlier nationwide demonstration for the eight-hour workday. At the earlier demonstration, clashes between police and strikers at the International Harvester Company of Chicago led to the death of a striking worker. The anarchist group decided to hold a protest the following night in Haymarket Square, and, although the protest was quiet, the police arrived armed for conflict. Someone in the crowd threw a bomb at the police, killing one officer and injuring another. The seven anarchists speaking at the protest were arrested and charged with murder. They were sentenced to death, though two were later pardoned and one committed suicide in prison before his execution. The press immediately blamed the KOL as well as Powderly for the Haymarket affair, despite the fact that neither the organization nor Powderly had anything to do with the demonstration. Combined with the American public’s lukewarm reception to organized labor as a whole, the damage was done. The KOL saw its membership decline to barely 100,000 by the end of 1886. Nonetheless, during its brief success, the Knights illustrated the potential for success with their model of “industrial unionism,” which welcomed workers from all trades. Americana The Haymarket Rally On May 1, 1886, recognized internationally as a day for labor celebration, labor organizations around the country engaged in a national rally for the eight-hour workday. While the number of striking workers varied around the country, estimates are that between 300,000 and 500,000 workers protested in New York, Detroit, Chicago, and beyond. In Chicago, clashes between police and protesters led the police to fire into the crowd, resulting in fatalities. Afterward, angry at the deaths of the striking workers, organizers quickly organized a “mass meeting,” per the poster below ( Figure 18.13 ). While the meeting was intended to be peaceful, a large police presence made itself known, prompting one of the event organizers to state in his speech, “There seems to prevail the opinion in some quarters that this meeting has been called for the purpose of inaugurating a riot, hence these warlike preparations on the part of so-called ‘law and order.’ However, let me tell you at the beginning that this meeting has not been called for any such purpose. The object of this meeting is to explain the general situation of the eight-hour movement and to throw light upon various incidents in connection with it.” The mayor of Chicago later corroborated accounts of the meeting, noted that it was a peaceful rally, but as it was winding down, the police marched into the crowd, demanding they disperse. Someone in the crowd threw a bomb, killing one policeman immediately and wounding many others, some of whom died later. Despite the aggressive actions of the police, public opinion was strongly against the striking laborers. The New York Times , after the events played out, reported on it with the headline “Rioting and Bloodshed in the Streets of Chicago: Police Mowed Down with Dynamite.” Other papers echoed the tone and often exaggerated the chaos, undermining organized labor’s efforts and leading to the ultimate conviction and hanging of the rally organizers. Labor activists considered those hanged after the Haymarket affair to be martyrs for the cause and created an informal memorial at their gravesides in Park Forest, Illinois. During the effort to establish industrial unionism in the form of the KOL, craft unions had continued to operate. In 1886, twenty different craft unions met to organize a national federation of autonomous craft unions. This group became the American Federation of Labor (AFL), led by Samuel Gompers from its inception until his death in 1924. More so than any of its predecessors, the AFL focused almost all of its efforts on economic gains for its members, seldom straying into political issues other than those that had a direct impact upon working conditions. The AFL also kept a strict policy of not interfering in each union’s individual business. Rather, Gompers often settled disputes between unions, using the AFL to represent all unions of matters of federal legislation that could affect all workers, such as the eight-hour workday. By 1900, the AFL had 500,000 members; by 1914, its numbers had risen to one million, and by 1920 they claimed four million working members. Still, as a federation of craft unions, it excluded many factory workers and thus, even at its height, represented only 15 percent of the nonfarm workers in the country. As a result, even as the country moved towards an increasingly industrial age, the majority of American workers still lacked support, protection from ownership, and access to upward mobility. The Decline of Labor: The Homestead and Pullman Strikes While workers struggled to find the right organizational structure to support a union movement in a society that was highly critical of such worker organization, there came two final violent events at the close of the nineteenth century. These events, the Homestead Steel Strike of 1892 and the Pullman Strike of 1894, all but crushed the labor movement for the next forty years, leaving public opinion of labor strikes lower than ever and workers unprotected. At the Homestead factory of the Carnegie Steel Company, workers represented by the Amalgamated Association of Iron and Steel Workers enjoyed relatively good relations with management until Henry C. Frick became the factory manager in 1889. When the union contract was up for renewal in 1892, Carnegie—long a champion of living wages for his employees—had left for Scotland and trusted Frick—noted for his strong anti-union stance—to manage the negotiations. When no settlement was reached by June 29, Frick ordered a lockout of the workers and hired three hundred Pinkerton detectives to protect company property. On July 6, as the Pinkertons arrived on barges on the river, union workers along the shore engaged them in a gunfight that resulted in the deaths of three Pinkertons and six workers. One week later, the Pennsylvania militia arrived to escort strike-breakers into the factory to resume production. Although the lockout continued until November, it ended with the union defeated and individual workers asking for their jobs back. A subsequent failed assassination attempt by anarchist Alexander Berkman on Frick further strengthened public animosity towards the union. Two years later, in 1894, the Pullman Strike was another disaster for unionized labor. The crisis began in the company town of Pullman, Illinois, where Pullman “sleeper” cars were manufactured for America’s railroads. When the depression of 1893 unfolded in the wake of the failure of several northeastern railroad companies, mostly due to overconstruction and poor financing, company owner George Pullman fired three thousand of the factory’s six thousand employees, cut the remaining workers’ wages by an average of 25 percent, and then continued to charge the same high rents and prices in the company homes and store where workers were required to live and shop. Workers began the strike on May 11, when Eugene V. Debs, the president of the American Railway Union, ordered rail workers throughout the country to stop handling any trains that had Pullman cars on them. In practicality, almost all of the trains fell into this category, and, therefore, the strike created a nationwide train stoppage, right on the heels of the depression of 1893. Seeking justification for sending in federal troops, President Grover Cleveland turned to his attorney general, who came up with a solution: Attach a mail car to every train and then send in troops to ensure the delivery of the mail. The government also ordered the strike to end; when Debs refused, he was arrested and imprisoned for his interference with the delivery of U.S. mail. The image below ( Figure 18.14 ) shows the standoff between federal troops and the workers. The troops protected the hiring of new workers, thus rendering the strike tactic largely ineffective. The strike ended abruptly on July 13, with no labor gains and much lost in the way of public opinion. My Story George Estes on the Order of Railroad Telegraphers The following excerpt is a reflection from George Estes, an organizer and member of the Order of Railroad Telegraphers, a labor organization at the end of the nineteenth century. His perspective on the ways that labor and management related to each other illustrates the difficulties at the heart of their negotiations. He notes that, in this era, the two groups saw each other as enemies and that any gain by one was automatically a loss by the other. I have always noticed that things usually have to get pretty bad before they get any better. When inequities pile up so high that the burden is more than the underdog can bear, he gets his dander up and things begin to happen. It was that way with the telegraphers’ problem. These exploited individuals were determined to get for themselves better working conditions—higher pay, shorter hours, less work which might not properly be classed as telegraphy, and the high and mighty Mr. Fillmore [railroad company president] was not going to stop them. It was a bitter fight. At the outset, Mr. Fillmore let it be known, by his actions and comments, that he held the telegraphers in the utmost contempt. With the papers crammed each day with news of labor strife—and with two great labor factions at each other’s throats, I am reminded of a parallel in my own early and more active career. Shortly before the turn of the century, in 1898 and 1899 to be more specific, I occupied a position with regard to a certain class of skilled labor, comparable to that held by the Lewises and Greens of today. I refer, of course, to the telegraphers and station agents. These hard-working gentlemen—servants of the public—had no regular hours, performed a multiplicity of duties, and, considering the service they rendered, were sorely and inadequately paid. A telegrapher’s day included a considerable number of chores that present-day telegraphers probably never did or will do in the course of a day’s work. He used to clean and fill lanterns, block lights, etc. Used to do the janitor work around the small town depot, stoke the pot-bellied stove of the waiting-room, sweep the floors, picking up papers and waiting-room litter. . . . Today, capital and labor seem to understand each other better than they did a generation or so ago. Capital is out to make money. So is labor—and each is willing to grant the other a certain amount of tolerant leeway, just so he doesn’t go too far. In the old days there was a breach as wide as the Pacific separating capital and labor. It wasn’t money altogether in those days, it was a matter of principle. Capital and labor couldn’t see eye to eye on a single point. Every gain that either made was at the expense of the other, and was fought tooth and nail. No difference seemed ever possible of amicable settlement. Strikes were riots. Murder and mayhem was common. Railroad labor troubles were frequent. The railroads, in the nineties, were the country’s largest employers. They were so big, so powerful, so perfectly organized themselves—I mean so in accord among themselves as to what treatment they felt like offering the man who worked for them—that it was extremely difficult for labor to gain a single advantage in the struggle for better conditions. —George Estes, interview with Andrew Sherbert, 1938 18.4 A New American Consumer Culture Learning Objectives By the end of this section, you will be able to: Describe the characteristics of the new consumer culture that emerged at the end of the nineteenth century Despite the challenges workers faced in their new roles as wage earners, the rise of industry in the United States allowed people to access and consume goods as never before. The rise of big business had turned America into a culture of consumers desperate for time-saving and leisure commodities, where people could expect to find everything they wanted in shops or by mail order. Gone were the days where the small general store was the only option for shoppers; at the end of the nineteenth century, people could take a train to the city and shop in large department stores like Macy’s in New York, Gimbel’s in Philadelphia, and Marshall Field's in Chicago. Chain stores, like A&P and Woolworth’s, both of which opened in the 1870s, offered options to those who lived farther from major urban areas and clearly catered to classes other than the wealthy elite. Industrial advancements contributed to this proliferation, as new construction techniques permitted the building of stores with higher ceilings for larger displays, and the production of larger sheets of plate glass lent themselves to the development of larger store windows, glass countertops, and display cases where shoppers could observe a variety of goods at a glance. L. Frank Baum, of Wizard of Oz fame, later founded the National Association of Window Trimmers in 1898, and began publishing The Store Window journal to advise businesses on space usage and promotion. Even families in rural America had new opportunities to purchase a greater variety of products than ever before, at ever decreasing prices. Those far from chain stores could benefit from the newly developed business of mail-order catalogs, placing orders by telephone. Aaron Montgomery Ward established the first significant mail-order business in 1872, with Sears, Roebuck & Company following in 1886. Sears distributed over 300,000 catalogs annually by 1897, and later broke the one million annual mark in 1907. Sears in particular understood that farmers and rural Americans sought alternatives to the higher prices and credit purchases they were forced to endure at small-town country stores. By clearly stating the prices in his catalog, Richard Sears steadily increased his company’s image of their catalog serving as “the consumer’s bible.” In the process, Sears, Roebuck & Company supplied much of America’s hinterland with products ranging from farm supplies to bicycles, toilet paper to automobiles, as seen below in a page from the catalog ( Figure 18.15 ). The tremendous variety of goods available for sale required businesses to compete for customers in ways they had never before imagined. Suddenly, instead of a single option for clothing or shoes, customers were faced with dozens, whether ordered by mail, found at the local chain store, or lined up in massive rows at department stores. This new level of competition made advertising a vital component of all businesses. By 1900, American businesses were spending almost $100 million annually on advertising. Competitors offered “new and improved” models as frequently as possible in order to generate interest. From toothpaste and mouthwash to books on entertaining guests, new goods were constantly offered. Newspapers accommodated the demand for advertising by shifting their production to include full-page advertisements, as opposed to the traditional column width, agate-type advertisements that dominated mid-nineteenth century newspapers (similar to classified advertisements in today’s publications). Likewise, professional advertising agencies began to emerge in the 1880s, with experts in consumer demand bidding for accounts with major firms. It may seem strange that, at a time when wages were so low, people began buying readily; however, the slow emergence of a middle class by the end of the century, combined with the growing practice of buying on credit, presented more opportunities to take part in the new consumer culture. Stores allowed people to open accounts and purchase on credit, thus securing business and allowing consumers to buy without ready cash. Then, as today, the risks of buying on credit led many into debt. As advertising expert Roland Marchand described in his Parable on the Democracy of Goods , in an era when access to products became more important than access to the means of production, Americans quickly accepted the notion that they could live a better lifestyle by purchasing the right clothes, the best hair cream, and the shiniest shoes, regardless of their class. For better or worse, American consumerism had begun. Americana Advertising in the Industrial Age: Credit, Luxury, and the Advent of “New and Improved” Before the industrial revolution, most household goods were either made at home or purchased locally, with limited choices. By the end of the nineteenth century, factors such as the population’s move towards urban centers and the expansion of the railroad changed how Americans shopped for, and perceived, consumer goods. As mentioned above, advertising took off, as businesses competed for customers. Many of the elements used widely in nineteenth-century advertisements are familiar. Companies sought to sell luxury, safety, and, as the ad for the typewriter below shows ( Figure 18.16 ), the allure of the new-and-improved model. One advertising tactic that truly took off in this era was the option to purchase on credit. For the first time, mail order and mass production meant that the aspiring middle class could purchase items that could only be owned previously by the wealthy. While there was a societal stigma for buying everyday goods on credit, certain items, such as fine furniture or pianos, were considered an investment in the move toward entry into the middle class. Additionally, farmers and housewives purchased farm equipment and sewing machines on credit, considering these items investments rather than luxuries. For women, the purchase of a sewing machine meant that a shirt could be made in one hour, instead of fourteen. The Singer Sewing Machine Company was one of the most aggressive at pushing purchase on credit. They advertised widely, and their “Dollar Down, Dollar a Week” campaign made them one of the fastest-growing companies in the country. For workers earning lower wages, these easy credit terms meant that the middle-class lifestyle was within their reach. Of course, it also meant they were in debt, and changes in wages, illness, or other unexpected expenses could wreak havoc on a household’s tenuous finances. Still, the opportunity to own new and luxurious products was one that many Americans, aspiring to improve their place in society, could not resist.
anatomy_and_physiology
Chapter Objectives After studying this chapter, you will be able to: List and describe the functions of bones Describe the classes of bones Discuss the process of bone formation and development Explain how bone repairs itself after a fracture Discuss the effect of exercise, nutrition, and hormones on bone tissue Describe how an imbalance of calcium can affect bone tissue Introduction Bones make good fossils. While the soft tissue of a once living organism will decay and fall away over time, bone tissue will, under the right conditions, undergo a process of mineralization, effectively turning the bone to stone. A well-preserved fossil skeleton can give us a good sense of the size and shape of an organism, just as your skeleton helps to define your size and shape. Unlike a fossil skeleton, however, your skeleton is a structure of living tissue that grows, repairs, and renews itself. The bones within it are dynamic and complex organs that serve a number of important functions, including some necessary to maintain homeostasis.
[ { "answer": { "ans_choice": 1, "ans_text": "protection of internal organs" }, "bloom": "1", "hl_context": "<hl> Bones also protect internal organs from injury by covering or surrounding them . <hl> For example , your ribs protect your lungs and heart , the bones of your vertebral column ( spine ) protect your spinal cord , and the bones of your cranium ( skull ) protect your brain ( Figure 6.3 ) .", "hl_sentences": "Bones also protect internal organs from injury by covering or surrounding them .", "question": { "cloze_format": "The function of the skeletal system that would be especially important if you were in a car accident is the ___.", "normal_format": "Which function of the skeletal system would be especially important if you were in a car accident?", "question_choices": [ "storage of minerals", "protection of internal organs", "facilitation of movement", "fat storage" ], "question_id": "fs-id1073754", "question_text": "Which function of the skeletal system would be especially important if you were in a car accident?" }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 3, "ans_text": "dense, hard connective tissue" }, "bloom": "1", "hl_context": "<hl> Bone , or osseous tissue , is a hard , dense connective tissue that forms most of the adult skeleton , the support structure of the body . <hl> In the areas of the skeleton where bones move ( for example , the ribcage and joints ) , cartilage , a semi-rigid form of connective tissue , provides flexibility and smooth surfaces for movement . The skeletal system is the body system composed of bones and cartilage and performs the following critical functions for the human body :", "hl_sentences": "Bone , or osseous tissue , is a hard , dense connective tissue that forms most of the adult skeleton , the support structure of the body .", "question": { "cloze_format": "Bone tissue can be described as ________.", "normal_format": "What can bone tissue be described as?", "question_choices": [ "dead calcified tissue", "cartilage", "the skeletal system", "dense, hard connective tissue" ], "question_id": "fs-id1516749", "question_text": "Bone tissue can be described as ________." }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 2, "ans_text": "make blood cells" }, "bloom": "1", "hl_context": "On a metabolic level , bone tissue performs several critical functions . For one , the bone matrix acts as a reservoir for a number of minerals important to the functioning of the body , especially calcium , and phosphorus . These minerals , incorporated into bone tissue , can be released back into the bloodstream to maintain levels needed to support physiological processes . Calcium ions , for example , are essential for muscle contractions and controlling the flow of other ions involved in the transmission of nerve impulses . <hl> Bone also serves as a site for fat storage and blood cell production . <hl> <hl> The softer connective tissue that fills the interior of most bone is referred to as bone marrow ( Figure 6.5 ) . <hl> There are two types of bone marrow : yellow marrow and red marrow . Yellow marrow contains adipose tissue ; the triglycerides stored in the adipocytes of the tissue can serve as a source of energy . <hl> Red marrow is where hematopoiesis — the production of blood cells — takes place . <hl> <hl> Red blood cells , white blood cells , and platelets are all produced in the red marrow . <hl> 6.2 Bone Classification Learning Objectives By the end of this section , you will be able to :", "hl_sentences": "Bone also serves as a site for fat storage and blood cell production . The softer connective tissue that fills the interior of most bone is referred to as bone marrow ( Figure 6.5 ) . Red marrow is where hematopoiesis — the production of blood cells — takes place . Red blood cells , white blood cells , and platelets are all produced in the red marrow .", "question": { "cloze_format": "Without red marrow, bones would not be able to ________.", "normal_format": "Without red bone marrow, bones would not be able to do what?", "question_choices": [ "store phosphate", "store calcium", "make blood cells", "move like levers" ], "question_id": "fs-id1500247", "question_text": "Without red marrow, bones would not be able to ________." }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 0, "ans_text": "an area of fat storage" }, "bloom": "1", "hl_context": "On a metabolic level , bone tissue performs several critical functions . For one , the bone matrix acts as a reservoir for a number of minerals important to the functioning of the body , especially calcium , and phosphorus . These minerals , incorporated into bone tissue , can be released back into the bloodstream to maintain levels needed to support physiological processes . Calcium ions , for example , are essential for muscle contractions and controlling the flow of other ions involved in the transmission of nerve impulses . <hl> Bone also serves as a site for fat storage and blood cell production . <hl> The softer connective tissue that fills the interior of most bone is referred to as bone marrow ( Figure 6.5 ) . There are two types of bone marrow : yellow marrow and red marrow . <hl> Yellow marrow contains adipose tissue ; the triglycerides stored in the adipocytes of the tissue can serve as a source of energy . <hl> Red marrow is where hematopoiesis — the production of blood cells — takes place . Red blood cells , white blood cells , and platelets are all produced in the red marrow . 6.2 Bone Classification Learning Objectives By the end of this section , you will be able to :", "hl_sentences": "Bone also serves as a site for fat storage and blood cell production . Yellow marrow contains adipose tissue ; the triglycerides stored in the adipocytes of the tissue can serve as a source of energy .", "question": { "cloze_format": "Yellow marrow has been identified as ________.", "normal_format": "Yellow marrow has been identified as what?", "question_choices": [ "an area of fat storage", "a point of attachment for muscles", "the hard portion of bone", "the cause of kyphosis" ], "question_id": "fs-id774002", "question_text": "Yellow marrow has been identified as ________." }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 1, "ans_text": "cartilage" }, "bloom": "1", "hl_context": "Bone , or osseous tissue , is a hard , dense connective tissue that forms most of the adult skeleton , the support structure of the body . <hl> In the areas of the skeleton where bones move ( for example , the ribcage and joints ) , cartilage , a semi-rigid form of connective tissue , provides flexibility and smooth surfaces for movement . <hl> The skeletal system is the body system composed of bones and cartilage and performs the following critical functions for the human body :", "hl_sentences": "In the areas of the skeleton where bones move ( for example , the ribcage and joints ) , cartilage , a semi-rigid form of connective tissue , provides flexibility and smooth surfaces for movement .", "question": { "cloze_format": "___ can be found in areas of movement.", "normal_format": "Which of the following can be found in areas of movement?", "question_choices": [ "hematopoiesis", "cartilage", "yellow marrow", "red marrow" ], "question_id": "fs-id1184558", "question_text": "Which of the following can be found in areas of movement?" }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 1, "ans_text": "bones and cartilage" }, "bloom": "1", "hl_context": "<hl> Just as the steel beams of a building provide a scaffold to support its weight , the bones and cartilage of your skeletal system compose the scaffold that supports the rest of your body . <hl> Without the skeletal system , you would be a limp mass of organs , muscle , and skin .", "hl_sentences": "Just as the steel beams of a building provide a scaffold to support its weight , the bones and cartilage of your skeletal system compose the scaffold that supports the rest of your body .", "question": { "cloze_format": "The skeletal system is made of ________.", "normal_format": "What is the skeletal system made of?", "question_choices": [ "muscles and tendons", "bones and cartilage", "vitreous humor", "minerals and fat" ], "question_id": "fs-id1258255", "question_text": "The skeletal system is made of ________." }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 1, "ans_text": "short bones" }, "bloom": "1", "hl_context": "<hl> A short bone is one that is cube-like in shape , being approximately equal in length , width , and thickness . <hl> <hl> The only short bones in the human skeleton are in the carpals of the wrists and the tarsals of the ankles . <hl> Short bones provide stability and support as well as some limited motion .", "hl_sentences": "A short bone is one that is cube-like in shape , being approximately equal in length , width , and thickness . The only short bones in the human skeleton are in the carpals of the wrists and the tarsals of the ankles .", "question": { "cloze_format": "Most of the bones of the arms and hands are long bones; however, the bones in the wrist are categorized as ________.", "normal_format": "Most of the bones of the arms and hands are long bones; however, what are the bones in the wrist categorized as?", "question_choices": [ "flat bones", "short bones", "sesamoid bones", "irregular bones" ], "question_id": "fs-id1859097", "question_text": "Most of the bones of the arms and hands are long bones; however, the bones in the wrist are categorized as ________." }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 3, "ans_text": "tendons" }, "bloom": "1", "hl_context": "<hl> A sesamoid bone is a small , round bone that , as the name suggests , is shaped like a sesame seed . <hl> <hl> These bones form in tendons ( the sheaths of tissue that connect bones to muscles ) where a great deal of pressure is generated in a joint . <hl> The sesamoid bones protect tendons by helping them overcome compressive forces . Sesamoid bones vary in number and placement from person to person but are typically found in tendons associated with the feet , hands , and knees . The patellae ( singular = patella ) are the only sesamoid bones found in common with every person . Table 6.1 reviews bone classifications with their associated features , functions , and examples .", "hl_sentences": "A sesamoid bone is a small , round bone that , as the name suggests , is shaped like a sesame seed . These bones form in tendons ( the sheaths of tissue that connect bones to muscles ) where a great deal of pressure is generated in a joint .", "question": { "cloze_format": "Sesamoid bones are found embedded in ________.", "normal_format": "What are sesamoid bones found embedded in?", "question_choices": [ "joints", "muscles", "ligaments", "tendons" ], "question_id": "fs-id1057151", "question_text": "Sesamoid bones are found embedded in ________." }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 0, "ans_text": "irregular" }, "bloom": "1", "hl_context": "<hl> An irregular bone is one that does not have any easily characterized shape and therefore does not fit any other classification . <hl> <hl> These bones tend to have more complex shapes , like the vertebrae that support the spinal cord and protect it from compressive forces . <hl> Many facial bones , particularly the ones containing sinuses , are classified as irregular bones .", "hl_sentences": "An irregular bone is one that does not have any easily characterized shape and therefore does not fit any other classification . These bones tend to have more complex shapes , like the vertebrae that support the spinal cord and protect it from compressive forces .", "question": { "cloze_format": "Bones that surround the spinal cord are classified as ________ bones.", "normal_format": "Bones that surround the spinal cord are classified as which bones?", "question_choices": [ "irregular", "sesamoid", "flat", "short" ], "question_id": "fs-id1434572", "question_text": "Bones that surround the spinal cord are classified as ________ bones." }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 0, "ans_text": "long bone" }, "bloom": "1", "hl_context": "A long bone is one that is cylindrical in shape , being longer than it is wide . Keep in mind , however , that the term describes the shape of a bone , not its size . <hl> Long bones are found in the arms ( humerus , ulna , radius ) and legs ( femur , tibia , fibula ) , as well as in the fingers ( metacarpals , phalanges ) and toes ( metatarsals , phalanges ) . <hl> Long bones function as levers ; they move when muscles contract .", "hl_sentences": "Long bones are found in the arms ( humerus , ulna , radius ) and legs ( femur , tibia , fibula ) , as well as in the fingers ( metacarpals , phalanges ) and toes ( metatarsals , phalanges ) .", "question": { "cloze_format": "The category of bone that is among the most numerous in the skeleton is ___.", "normal_format": "Which category of bone is among the most numerous in the skeleton?", "question_choices": [ "long bone", "sesamoid bone", "short bone", "flat bone" ], "question_id": "fs-id691668", "question_text": "Which category of bone is among the most numerous in the skeleton?" }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 2, "ans_text": "lever" }, "bloom": "1", "hl_context": "A long bone is one that is cylindrical in shape , being longer than it is wide . Keep in mind , however , that the term describes the shape of a bone , not its size . Long bones are found in the arms ( humerus , ulna , radius ) and legs ( femur , tibia , fibula ) , as well as in the fingers ( metacarpals , phalanges ) and toes ( metatarsals , phalanges ) . <hl> Long bones function as levers ; they move when muscles contract . <hl>", "hl_sentences": "Long bones function as levers ; they move when muscles contract .", "question": { "cloze_format": "Long bones enable body movement by acting as a ________.", "normal_format": "Long bones enable body movement by acting as a what?", "question_choices": [ "counterweight", "resistive force", "lever", "fulcrum" ], "question_id": "fs-id1284008", "question_text": "Long bones enable body movement by acting as a ________." }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 2, "ans_text": "hematopoiesis" }, "bloom": null, "hl_context": "Like compact bone , spongy bone , also known as cancellous bone , contains osteocytes housed in lacunae , but they are not arranged in concentric circles . Instead , the lacunae and osteocytes are found in a lattice-like network of matrix spikes called trabeculae ( singular = trabecula ) ( Figure 6.13 ) . The trabeculae may appear to be a random network , but each trabecula forms along lines of stress to provide strength to the bone . The spaces of the trabeculated network provide balance to the dense and heavy compact bone by making bones lighter so that muscles can move them more easily . <hl> In addition , the spaces in some spongy bones contain red marrow , protected by the trabeculae , where hematopoiesis occurs . <hl> <hl> The wider section at each end of the bone is called the epiphysis ( plural = epiphyses ) , which is filled with spongy bone . <hl> <hl> Red marrow fills the spaces in the spongy bone . <hl> Each epiphysis meets the diaphysis at the metaphysis , the narrow area that contains the epiphyseal plate ( growth plate ) , a layer of hyaline ( transparent ) cartilage in a growing bone . When the bone stops growing in early adulthood ( approximately 18 – 21 years ) , the cartilage is replaced by osseous tissue and the epiphyseal plate becomes an epiphyseal line .", "hl_sentences": "In addition , the spaces in some spongy bones contain red marrow , protected by the trabeculae , where hematopoiesis occurs . The wider section at each end of the bone is called the epiphysis ( plural = epiphyses ) , which is filled with spongy bone . Red marrow fills the spaces in the spongy bone .", "question": { "cloze_format": "___ occurs in the spongy bone of the epiphysis.", "normal_format": "Which of the following occurs in the spongy bone of the epiphysis?", "question_choices": [ "bone growth", "bone remodeling", "hematopoiesis", "shock absorption" ], "question_id": "fs-id1509482", "question_text": "Which of the following occurs in the spongy bone of the epiphysis?" }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 1, "ans_text": "fat stores" }, "bloom": "1", "hl_context": "The structure of a long bone allows for the best visualization of all of the parts of a bone ( Figure 6.7 ) . A long bone has two parts : the diaphysis and the epiphysis . The diaphysis is the tubular shaft that runs between the proximal and distal ends of the bone . <hl> The hollow region in the diaphysis is called the medullary cavity , which is filled with yellow marrow . <hl> The walls of the diaphysis are composed of dense and hard compact bone . On a metabolic level , bone tissue performs several critical functions . For one , the bone matrix acts as a reservoir for a number of minerals important to the functioning of the body , especially calcium , and phosphorus . These minerals , incorporated into bone tissue , can be released back into the bloodstream to maintain levels needed to support physiological processes . Calcium ions , for example , are essential for muscle contractions and controlling the flow of other ions involved in the transmission of nerve impulses . Bone also serves as a site for fat storage and blood cell production . The softer connective tissue that fills the interior of most bone is referred to as bone marrow ( Figure 6.5 ) . There are two types of bone marrow : yellow marrow and red marrow . <hl> Yellow marrow contains adipose tissue ; the triglycerides stored in the adipocytes of the tissue can serve as a source of energy . <hl> Red marrow is where hematopoiesis — the production of blood cells — takes place . Red blood cells , white blood cells , and platelets are all produced in the red marrow . 6.2 Bone Classification Learning Objectives By the end of this section , you will be able to :", "hl_sentences": "The hollow region in the diaphysis is called the medullary cavity , which is filled with yellow marrow . Yellow marrow contains adipose tissue ; the triglycerides stored in the adipocytes of the tissue can serve as a source of energy .", "question": { "cloze_format": "The diaphysis contains ________.", "normal_format": "What does the diaphysis contain?", "question_choices": [ "the metaphysis", "fat stores", "spongy bone", "compact bone" ], "question_id": "fs-id1521592", "question_text": "The diaphysis contains ________." }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 0, "ans_text": "periosteum" }, "bloom": "1", "hl_context": "The medullary cavity has a delicate membranous lining called the endosteum ( end - = “ inside ” ; oste - = “ bone ” ) , where bone growth , repair , and remodeling occur . <hl> The outer surface of the bone is covered with a fibrous membrane called the periosteum ( peri - = “ around ” or “ surrounding ” ) . <hl> The periosteum contains blood vessels , nerves , and lymphatic vessels that nourish compact bone . Tendons and ligaments also attach to bones at the periosteum . The periosteum covers the entire outer surface except where the epiphyses meet other bones to form joints ( Figure 6.8 ) . In this region , the epiphyses are covered with articular cartilage , a thin layer of cartilage that reduces friction and acts as a shock absorber .", "hl_sentences": "The outer surface of the bone is covered with a fibrous membrane called the periosteum ( peri - = “ around ” or “ surrounding ” ) .", "question": { "cloze_format": "The fibrous membrane covering the outer surface of the bone is the ________.", "normal_format": "Which is the fibrous membrane covering the outer surface of the bone?", "question_choices": [ "periosteum", "epiphysis", "endosteum", "diaphysis" ], "question_id": "fs-id1286871", "question_text": "The fibrous membrane covering the outer surface of the bone is the ________." }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 1, "ans_text": "osteocytes and osteoclasts" }, "bloom": null, "hl_context": "<hl> If osteoblasts and osteocytes are incapable of mitosis , then how are they replenished when old ones die ? <hl> The answer lies in the properties of a third category of bone cells — the osteogenic cell . These osteogenic cells are undifferentiated with high mitotic activity and they are the only bone cells that divide . Immature osteogenic cells are found in the deep layers of the periosteum and the marrow . They differentiate and develop into osteoblasts .", "hl_sentences": "If osteoblasts and osteocytes are incapable of mitosis , then how are they replenished when old ones die ?", "question": { "cloze_format": "___ are incapable of undergoing mitosis.", "normal_format": "Which of the following are incapable of undergoing mitosis?", "question_choices": [ "osteoblasts and osteoclasts", "osteocytes and osteoclasts", "osteoblasts and osteocytes", "osteogenic cells and osteoclasts" ], "question_id": "fs-id320806", "question_text": "Which of the following are incapable of undergoing mitosis?" }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 1, "ans_text": "osteoclasts" }, "bloom": null, "hl_context": "The dynamic nature of bone means that new tissue is constantly formed , and old , injured , or unnecessary bone is dissolved for repair or for calcium release . <hl> The cell responsible for bone resorption , or breakdown , is the osteoclast . <hl> <hl> They are found on bone surfaces , are multinucleated , and originate from monocytes and macrophages , two types of white blood cells , not from osteogenic cells . <hl> Osteoclasts are continually breaking down old bone while osteoblasts are continually forming new bone . The ongoing balance between osteoblasts and osteoclasts is responsible for the constant but subtle reshaping of bone . Table 6.3 reviews the bone cells , their functions , and locations .", "hl_sentences": "The cell responsible for bone resorption , or breakdown , is the osteoclast . They are found on bone surfaces , are multinucleated , and originate from monocytes and macrophages , two types of white blood cells , not from osteogenic cells .", "question": { "cloze_format": "Cells that do not originate from osteogenic cells are ___.", "normal_format": "Which cells do not originate from osteogenic cells?", "question_choices": [ "osteoblasts", "osteoclasts", "osteocytes", "osteoprogenitor cells" ], "question_id": "fs-id1107187", "question_text": "Which cells do not originate from osteogenic cells?" }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 2, "ans_text": "lamellae" }, "bloom": "1", "hl_context": "<hl> Like compact bone , spongy bone , also known as cancellous bone , contains osteocytes housed in lacunae , but they are not arranged in concentric circles . <hl> <hl> Instead , the lacunae and osteocytes are found in a lattice-like network of matrix spikes called trabeculae ( singular = trabecula ) ( Figure 6.13 ) . <hl> The trabeculae may appear to be a random network , but each trabecula forms along lines of stress to provide strength to the bone . The spaces of the trabeculated network provide balance to the dense and heavy compact bone by making bones lighter so that muscles can move them more easily . In addition , the spaces in some spongy bones contain red marrow , protected by the trabeculae , where hematopoiesis occurs . <hl> The osteocytes are located inside spaces called lacunae ( singular = lacuna ) , found at the borders of adjacent lamellae . <hl> As described earlier , canaliculi connect with the canaliculi of other lacunae and eventually with the central canal . This system allows nutrients to be transported to the osteocytes and wastes to be removed from them . Spongy ( Cancellous ) Bone <hl> Compact Bone Compact bone is the denser , stronger of the two types of bone tissue ( Figure 6.12 ) . <hl> It can be found under the periosteum and in the diaphyses of long bones , where it provides support and protection . <hl> The microscopic structural unit of compact bone is called an osteon , or Haversian system . <hl> <hl> Each osteon is composed of concentric rings of calcified matrix called lamellae ( singular = lamella ) . <hl> Running down the center of each osteon is the central canal , or Haversian canal , which contains blood vessels , nerves , and lymphatic vessels . These vessels and nerves branch off at right angles through a perforating canal , also known as Volkmann ’ s canals , to extend to the periosteum and endosteum .", "hl_sentences": "Like compact bone , spongy bone , also known as cancellous bone , contains osteocytes housed in lacunae , but they are not arranged in concentric circles . Instead , the lacunae and osteocytes are found in a lattice-like network of matrix spikes called trabeculae ( singular = trabecula ) ( Figure 6.13 ) . The osteocytes are located inside spaces called lacunae ( singular = lacuna ) , found at the borders of adjacent lamellae . Compact Bone Compact bone is the denser , stronger of the two types of bone tissue ( Figure 6.12 ) . The microscopic structural unit of compact bone is called an osteon , or Haversian system . Each osteon is composed of concentric rings of calcified matrix called lamellae ( singular = lamella ) .", "question": { "cloze_format": "___ are found in compact bone and cancellous bone.", "normal_format": "Which of the following are found in compact bone and cancellous bone?", "question_choices": [ "Haversian systems", "Haversian canals", "lamellae", "lacunae" ], "question_id": "fs-id1419507", "question_text": "Which of the following are found in compact bone and cancellous bone?" }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 2, "ans_text": "trabeculae" }, "bloom": "1", "hl_context": "<hl> Like compact bone , spongy bone , also known as cancellous bone , contains osteocytes housed in lacunae , but they are not arranged in concentric circles . <hl> <hl> Instead , the lacunae and osteocytes are found in a lattice-like network of matrix spikes called trabeculae ( singular = trabecula ) ( Figure 6.13 ) . <hl> The trabeculae may appear to be a random network , but each trabecula forms along lines of stress to provide strength to the bone . The spaces of the trabeculated network provide balance to the dense and heavy compact bone by making bones lighter so that muscles can move them more easily . In addition , the spaces in some spongy bones contain red marrow , protected by the trabeculae , where hematopoiesis occurs .", "hl_sentences": "Like compact bone , spongy bone , also known as cancellous bone , contains osteocytes housed in lacunae , but they are not arranged in concentric circles . Instead , the lacunae and osteocytes are found in a lattice-like network of matrix spikes called trabeculae ( singular = trabecula ) ( Figure 6.13 ) .", "question": { "cloze_format": "___ are only found in cancellous bone.", "normal_format": "Which of the following are only found in cancellous bone?", "question_choices": [ "canaliculi", "Volkmann’s canals", "trabeculae", "calcium salts" ], "question_id": "fs-id1059498", "question_text": "Which of the following are only found in cancellous bone?" }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 0, "ans_text": "a hole" }, "bloom": "1", "hl_context": "The spongy bone and medullary cavity receive nourishment from arteries that pass through the compact bone . <hl> The arteries enter through the nutrient foramen ( plural = foramina ) , small openings in the diaphysis ( Figure 6.15 ) . <hl> <hl> The osteocytes in spongy bone are nourished by blood vessels of the periosteum that penetrate spongy bone and blood that circulates in the marrow cavities . <hl> As the blood passes through the marrow cavities , it is collected by veins , which then pass out of the bone through the foramina . <hl> Foramen ( holes through which blood vessels can pass through ) <hl>", "hl_sentences": "The arteries enter through the nutrient foramen ( plural = foramina ) , small openings in the diaphysis ( Figure 6.15 ) . The osteocytes in spongy bone are nourished by blood vessels of the periosteum that penetrate spongy bone and blood that circulates in the marrow cavities . Foramen ( holes through which blood vessels can pass through )", "question": { "cloze_format": "The area of a bone where the nutrient foramen passes forms a ___ .", "normal_format": "The area of a bone where the nutrient foramen passes forms what kind of bone marking?", "question_choices": [ "a hole", "a facet", "a canal", "a fissure" ], "question_id": "fs-id756448", "question_text": "The area of a bone where the nutrient foramen passes forms what kind of bone marking?" }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 2, "ans_text": "because it does not have a blood supply" }, "bloom": null, "hl_context": "Bone is a replacement tissue ; that is , it uses a model tissue on which to lay down its mineral matrix . For skeletal development , the most common template is cartilage . During fetal development , a framework is laid down that determines where bones will form . This framework is a flexible , semi-solid matrix produced by chondroblasts and consists of hyaluronic acid , chondroitin sulfate , collagen fibers , and water . As the matrix surrounds and isolates chondroblasts , they are called chondrocytes . <hl> Unlike most connective tissues , cartilage is avascular , meaning that it has no blood vessels supplying nutrients and removing metabolic wastes . <hl> <hl> All of these functions are carried on by diffusion through the matrix . <hl> <hl> This is why damaged cartilage does not repair itself as readily as most tissues do . <hl>", "hl_sentences": "Unlike most connective tissues , cartilage is avascular , meaning that it has no blood vessels supplying nutrients and removing metabolic wastes . All of these functions are carried on by diffusion through the matrix . This is why damaged cartilage does not repair itself as readily as most tissues do .", "question": { "cloze_format": "Cartilage is slow to heal ___.", "normal_format": "Why is cartilage slow to heal?", "question_choices": [ "because it eventually develops into bone", "because it is semi-solid and flexible", "because it does not have a blood supply", "because endochondral ossification replaces all cartilage with bone" ], "question_id": "fs-id1857810", "question_text": "Why is cartilage slow to heal?" }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 3, "ans_text": "Formation of osteoid spreads out the osteoblasts that formed the ossification centers." }, "bloom": "3", "hl_context": "The osteoblasts secrete osteoid , uncalcified matrix , which calcifies ( hardens ) within a few days as mineral salts are deposited on it , thereby entrapping the osteoblasts within . <hl> Once entrapped , the osteoblasts become osteocytes ( Figure 6.16 b ) . <hl> <hl> As osteoblasts transform into osteocytes , osteogenic cells in the surrounding connective tissue differentiate into new osteoblasts . <hl> The process begins when mesenchymal cells in the embryonic skeleton gather together and begin to differentiate into specialized cells ( Figure 6.16 a ) . <hl> Some of these cells will differentiate into capillaries , while others will become osteogenic cells and then osteoblasts . <hl> <hl> Although they will ultimately be spread out by the formation of bone tissue , early osteoblasts appear in a cluster called an ossification center . <hl>", "hl_sentences": "Once entrapped , the osteoblasts become osteocytes ( Figure 6.16 b ) . As osteoblasts transform into osteocytes , osteogenic cells in the surrounding connective tissue differentiate into new osteoblasts . Some of these cells will differentiate into capillaries , while others will become osteogenic cells and then osteoblasts . Although they will ultimately be spread out by the formation of bone tissue , early osteoblasts appear in a cluster called an ossification center .", "question": { "cloze_format": "The reason osteocytes are spread out in bone tissue is that ___ .", "normal_format": "Why are osteocytes spread out in bone tissue?", "question_choices": [ "They develop from mesenchymal cells.", "They are surrounded by osteoid.", "They travel through the capillaries.", "Formation of osteoid spreads out the osteoblasts that formed the ossification centers." ], "question_id": "fs-id1491618", "question_text": "Why are osteocytes spread out in bone tissue?" }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 1, "ans_text": "They die in the calcified matrix that surrounds them and form the medullary cavity." }, "bloom": "1", "hl_context": "As more matrix is produced , the chondrocytes in the center of the cartilaginous model grow in size . <hl> As the matrix calcifies , nutrients can no longer reach the chondrocytes . <hl> <hl> This results in their death and the disintegration of the surrounding cartilage . <hl> <hl> Blood vessels invade the resulting spaces , not only enlarging the cavities but also carrying osteogenic cells with them , many of which will become osteoblasts . <hl> <hl> These enlarging spaces eventually combine to become the medullary cavity . <hl> <hl> In a long bone , for example , at about 6 to 8 weeks after conception , some of the mesenchymal cells differentiate into chondrocytes ( cartilage cells ) that form the cartilaginous skeletal precursor of the bones ( Figure 6.17 a ) . <hl> Soon after , the perichondrium , a membrane that covers the cartilage , appears Figure 6.17 b ) . In endochondral ossification , bone develops by replacing hyaline cartilage . Cartilage does not become bone . Instead , cartilage serves as a template to be completely replaced by new bone . Endochondral ossification takes much longer than intramembranous ossification . <hl> Bones at the base of the skull and long bones form via endochondral ossification . <hl>", "hl_sentences": "As the matrix calcifies , nutrients can no longer reach the chondrocytes . This results in their death and the disintegration of the surrounding cartilage . Blood vessels invade the resulting spaces , not only enlarging the cavities but also carrying osteogenic cells with them , many of which will become osteoblasts . These enlarging spaces eventually combine to become the medullary cavity . In a long bone , for example , at about 6 to 8 weeks after conception , some of the mesenchymal cells differentiate into chondrocytes ( cartilage cells ) that form the cartilaginous skeletal precursor of the bones ( Figure 6.17 a ) . Bones at the base of the skull and long bones form via endochondral ossification .", "question": { "cloze_format": "In endochondral ossification, the effect on the chondrocytes is that ___", "normal_format": "In endochondral ossification, what happens to the chondrocytes?", "question_choices": [ "They develop into osteocytes.", "They die in the calcified matrix that surrounds them and form the medullary cavity.", "They grow and form the periosteum.", "They group together to form the primary ossification center." ], "question_id": "fs-id1525656", "question_text": "In endochondral ossification, what happens to the chondrocytes?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 3, "ans_text": "the flat bones of the cranium" }, "bloom": "1", "hl_context": "During intramembranous ossification , compact and spongy bone develops directly from sheets of mesenchymal ( undifferentiated ) connective tissue . <hl> The flat bones of the face , most of the cranial bones , and the clavicles ( collarbones ) are formed via intramembranous ossification . <hl>", "hl_sentences": "The flat bones of the face , most of the cranial bones , and the clavicles ( collarbones ) are formed via intramembranous ossification .", "question": { "cloze_format": "Bones that is (are) formed by intramembranous ossification is (are) ___ .", "normal_format": "Which of the following bones is (are) formed by intramembranous ossification?", "question_choices": [ "the metatarsals", "the femur", "the ribs", "the flat bones of the cranium" ], "question_id": "fs-id1235745", "question_text": "Which of the following bones is (are) formed by intramembranous ossification?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 0, "ans_text": "epiphyseal plate" }, "bloom": "1", "hl_context": "<hl> The epiphyseal plate is the area of growth in a long bone . <hl> It is a layer of hyaline cartilage where ossification occurs in immature bones . On the epiphyseal side of the epiphyseal plate , cartilage is formed . On the diaphyseal side , cartilage is ossified , and the diaphysis grows in length . The epiphyseal plate is composed of four zones of cells and activity ( Figure 6.18 ) . The reserve zone is the region closest to the epiphyseal end of the plate and contains small chondrocytes within the matrix . These chondrocytes do not participate in bone growth but secure the epiphyseal plate to the osseous tissue of the epiphysis .", "hl_sentences": "The epiphyseal plate is the area of growth in a long bone .", "question": { "cloze_format": "Bones grow in length due to activity in the ________.", "normal_format": "Bones grow in length due to activity in the what? ", "question_choices": [ "epiphyseal plate", "perichondrium", "periosteum", "medullary cavity" ], "question_id": "fs-id1511799", "question_text": "Bones grow in length due to activity in the ________." }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 1, "ans_text": "beneath the periosteum" }, "bloom": "1", "hl_context": "While bones are increasing in length , they are also increasing in diameter ; growth in diameter can continue even after longitudinal growth ceases . This is called appositional growth . Osteoclasts resorb old bone that lines the medullary cavity , while osteoblasts , via intramembranous ossification , produce new bone tissue beneath the periosteum . <hl> The erosion of old bone along the medullary cavity and the deposition of new bone beneath the periosteum not only increase the diameter of the diaphysis but also increase the diameter of the medullary cavity . <hl> This process is called modeling .", "hl_sentences": "The erosion of old bone along the medullary cavity and the deposition of new bone beneath the periosteum not only increase the diameter of the diaphysis but also increase the diameter of the medullary cavity .", "question": { "cloze_format": "Bones grow in diameter due to bone formation ________.", "normal_format": "Bones grow in diameter due to which bone formation?", "question_choices": [ "in the medullary cavity", "beneath the periosteum", "in the epiphyseal plate", "within the metaphysis" ], "question_id": "fs-id1331361", "question_text": "Bones grow in diameter due to bone formation ________." }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 2, "ans_text": "calcification, maturation, proliferation, reserved" }, "bloom": "1", "hl_context": "<hl> Most of the chondrocytes in the zone of calcified matrix , the zone closest to the diaphysis , are dead because the matrix around them has calcified . <hl> Capillaries and osteoblasts from the diaphysis penetrate this zone , and the osteoblasts secrete bone tissue on the remaining calcified cartilage . Thus , the zone of calcified matrix connects the epiphyseal plate to the diaphysis . A bone grows in length when osseous tissue is added to the diaphysis . <hl> The proliferative zone is the next layer toward the diaphysis and contains stacks of slightly larger chondrocytes . <hl> It makes new chondrocytes ( via mitosis ) to replace those that die at the diaphyseal end of the plate . <hl> Chondrocytes in the next layer , the zone of maturation and hypertrophy , are older and larger than those in the proliferative zone . <hl> <hl> The more mature cells are situated closer to the diaphyseal end of the plate . <hl> <hl> The longitudinal growth of bone is a result of cellular division in the proliferative zone and the maturation of cells in the zone of maturation and hypertrophy . <hl> The epiphyseal plate is the area of growth in a long bone . It is a layer of hyaline cartilage where ossification occurs in immature bones . On the epiphyseal side of the epiphyseal plate , cartilage is formed . On the diaphyseal side , cartilage is ossified , and the diaphysis grows in length . <hl> The epiphyseal plate is composed of four zones of cells and activity ( Figure 6.18 ) . <hl> <hl> The reserve zone is the region closest to the epiphyseal end of the plate and contains small chondrocytes within the matrix . <hl> These chondrocytes do not participate in bone growth but secure the epiphyseal plate to the osseous tissue of the epiphysis .", "hl_sentences": "Most of the chondrocytes in the zone of calcified matrix , the zone closest to the diaphysis , are dead because the matrix around them has calcified . The proliferative zone is the next layer toward the diaphysis and contains stacks of slightly larger chondrocytes . Chondrocytes in the next layer , the zone of maturation and hypertrophy , are older and larger than those in the proliferative zone . The more mature cells are situated closer to the diaphyseal end of the plate . The longitudinal growth of bone is a result of cellular division in the proliferative zone and the maturation of cells in the zone of maturation and hypertrophy . The epiphyseal plate is composed of four zones of cells and activity ( Figure 6.18 ) . The reserve zone is the region closest to the epiphyseal end of the plate and contains small chondrocytes within the matrix .", "question": { "cloze_format": "The correct sequence of zones in the epiphyseal plate is ___ .", "normal_format": "Which of the following represents the correct sequence of zones in the epiphyseal plate?", "question_choices": [ "proliferation, reserved, maturation, calcification", "maturation, proliferation, reserved, calcification", "calcification, maturation, proliferation, reserved", "calcification, reserved, proliferation, maturation" ], "question_id": "fs-id1282027", "question_text": "Which of the following represents the correct sequence of zones in the epiphyseal plate?" }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 1, "ans_text": "open and transverse" }, "bloom": "1", "hl_context": "Fractures are classified by their complexity , location , and other features ( Figure 6.20 ) . Table 6.4 outlines common types of fractures . <hl> Some fractures may be described using more than one term because it may have the features of more than one type ( e . g . , an open transverse fracture ) . <hl>", "hl_sentences": "Some fractures may be described using more than one term because it may have the features of more than one type ( e . g . , an open transverse fracture ) .", "question": { "cloze_format": "A fracture can be both ________.", "normal_format": "What can a fracture be?", "question_choices": [ "open and closed", "open and transverse", "transverse and greenstick", "greenstick and comminuted" ], "question_id": "fs-id1475727", "question_text": "A fracture can be both ________." }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 1, "ans_text": "The yellow marrow in the diaphysis is exposed and damaged." }, "bloom": null, "hl_context": "When a broken bone is manipulated and set into its natural position without surgery , the procedure is called a closed reduction . Open reduction requires surgery to expose the fracture and reset the bone . While some fractures can be minor , others are quite severe and result in grave complications . <hl> For example , a fractured diaphysis of the femur has the potential to release fat globules into the bloodstream . <hl> These can become lodged in the capillary beds of the lungs , leading to respiratory distress and if not treated quickly , death . The structure of a long bone allows for the best visualization of all of the parts of a bone ( Figure 6.7 ) . A long bone has two parts : the diaphysis and the epiphysis . The diaphysis is the tubular shaft that runs between the proximal and distal ends of the bone . <hl> The hollow region in the diaphysis is called the medullary cavity , which is filled with yellow marrow . <hl> The walls of the diaphysis are composed of dense and hard compact bone .", "hl_sentences": "For example , a fractured diaphysis of the femur has the potential to release fat globules into the bloodstream . The hollow region in the diaphysis is called the medullary cavity , which is filled with yellow marrow .", "question": { "cloze_format": "A fractured diaphysis can release fat globules into the bloodstream because ___.", "normal_format": "How can a fractured diaphysis release fat globules into the bloodstream?", "question_choices": [ "The bone pierces fat stores in the skin.", "The yellow marrow in the diaphysis is exposed and damaged.", "The injury triggers the body to release fat from healthy bones.", "The red marrow in the fractured bone releases fat to heal the fracture." ], "question_id": "fs-id1738815", "question_text": "How can a fractured diaphysis release fat globules into the bloodstream?" }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 3, "ans_text": "broken bone pierces the skin" }, "bloom": null, "hl_context": "<hl> A fracture in which at least one end of the broken bone tears through the skin ; carries a high risk of infection <hl> <hl> Open ( or compound ) <hl>", "hl_sentences": "A fracture in which at least one end of the broken bone tears through the skin ; carries a high risk of infection Open ( or compound )", "question": { "cloze_format": "In a compound fracture, ________.", "normal_format": "Which of the following is correct about a compound fracture?", "question_choices": [ "the break occurs at an angle to the bone", "the broken bone does not tear the skin", "one fragment of broken bone is compressed into the other", "broken bone pierces the skin" ], "question_id": "fs-id1752391", "question_text": "In a compound fracture, ________." }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 1, "ans_text": "trabecular bone" }, "bloom": null, "hl_context": "<hl> Eventually , the internal and external calli unite , compact bone replaces spongy bone at the outer margins of the fracture , and healing is complete . <hl> A slight swelling may remain on the outer surface of the bone , but quite often , that region undergoes remodeling ( Figure 6.21 d ) , and no external evidence of the fracture remains . Over the next several weeks , osteoclasts resorb the dead bone ; osteogenic cells become active , divide , and differentiate into osteoblasts . <hl> The cartilage in the calli is replaced by trabecular bone via endochondral ossification ( Figure 6.21 c ) . <hl>", "hl_sentences": "Eventually , the internal and external calli unite , compact bone replaces spongy bone at the outer margins of the fracture , and healing is complete . The cartilage in the calli is replaced by trabecular bone via endochondral ossification ( Figure 6.21 c ) .", "question": { "cloze_format": "The internal and external calli are replaced by ________.", "normal_format": "What internal and external calli are replaced by?", "question_choices": [ "hyaline cartilage", "trabecular bone", "osteogenic cells", "osteoclasts" ], "question_id": "fs-id2036066", "question_text": "The internal and external calli are replaced by ________." }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 2, "ans_text": "spongy" }, "bloom": "1", "hl_context": "<hl> Eventually , the internal and external calli unite , compact bone replaces spongy bone at the outer margins of the fracture , and healing is complete . <hl> A slight swelling may remain on the outer surface of the bone , but quite often , that region undergoes remodeling ( Figure 6.21 d ) , and no external evidence of the fracture remains .", "hl_sentences": "Eventually , the internal and external calli unite , compact bone replaces spongy bone at the outer margins of the fracture , and healing is complete .", "question": { "cloze_format": "The first type of bone to form during fracture repair is ________ bone.", "normal_format": "Which bone is the first type of bone to form duting fracture repair?", "question_choices": [ "compact", "lamellar", "spongy", "dense" ], "question_id": "fs-id1121987", "question_text": "The first type of bone to form during fracture repair is ________ bone." }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 0, "ans_text": "vitamin D" }, "bloom": "1", "hl_context": "You already know that calcium is a critical component of bone , especially in the form of calcium phosphate and calcium carbonate . Since the body cannot make calcium , it must be obtained from the diet . <hl> However , calcium cannot be absorbed from the small intestine without vitamin D . Therefore , intake of vitamin D is also critical to bone health . <hl> In addition to vitamin D ’ s role in calcium absorption , it also plays a role , though not as clearly understood , in bone remodeling .", "hl_sentences": "However , calcium cannot be absorbed from the small intestine without vitamin D . Therefore , intake of vitamin D is also critical to bone health .", "question": { "cloze_format": "Calcium cannot be absorbed from the small intestine if ________ is lacking.", "normal_format": "Calcium cannot be absorbed from the small intestine if which of the following is lacking?", "question_choices": [ "vitamin D", "vitamin K", "calcitonin", "fluoride" ], "question_id": "fs-id1506178", "question_text": "Calcium cannot be absorbed from the small intestine if ________ is lacking." }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 2, "ans_text": "leafy green vegetables" }, "bloom": "3", "hl_context": "<hl> Vitamin K also supports bone mineralization and may have a synergistic role with vitamin D in the regulation of bone growth . <hl> <hl> Green leafy vegetables are a good source of vitamin K . <hl>", "hl_sentences": "Vitamin K also supports bone mineralization and may have a synergistic role with vitamin D in the regulation of bone growth . Green leafy vegetables are a good source of vitamin K .", "question": { "cloze_format": "The food that is best for bone health is ___.", "normal_format": "Which one of the following foods is best for bone health?", "question_choices": [ "carrots", "liver", "leafy green vegetables", "oranges" ], "question_id": "fs-id1828403", "question_text": "Which one of the following foods is best for bone health?" }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 0, "ans_text": "estrogen and testosterone" }, "bloom": "1", "hl_context": "GH is not alone in stimulating bone growth and maintaining osseous tissue . Thyroxine , a hormone secreted by the thyroid gland promotes osteoblastic activity and the synthesis of bone matrix . <hl> During puberty , the sex hormones ( estrogen in girls , testosterone in boys ) also come into play . <hl> <hl> They too promote osteoblastic activity and production of bone matrix , and in addition , are responsible for the growth spurt that often occurs during adolescence . <hl> They also promote the conversion of the epiphyseal plate to the epiphyseal line ( i . e . , cartilage to its bony remnant ) , thus bringing an end to the longitudinal growth of bones . Additionally , calcitriol , the active form of vitamin D , is produced by the kidneys and stimulates the absorption of calcium and phosphate from the digestive tract .", "hl_sentences": "During puberty , the sex hormones ( estrogen in girls , testosterone in boys ) also come into play . They too promote osteoblastic activity and production of bone matrix , and in addition , are responsible for the growth spurt that often occurs during adolescence .", "question": { "cloze_format": "The hormones that are responsible for the adolescent growth spurt are ___.", "normal_format": "Which of the following hormones are responsible for the adolescent growth spurt?", "question_choices": [ "estrogen and testosterone", "calcitonin and calcitriol", "growth hormone and parathyroid hormone", "thyroxine and progesterone" ], "question_id": "fs-id1639450", "question_text": "Which of the following hormones are responsible for the adolescent growth spurt?" }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 3, "ans_text": "calcitonin and parathyroid hormone" }, "bloom": "3", "hl_context": "The small intestine is also affected by PTH , albeit indirectly . Because another function of PTH is to stimulate the synthesis of vitamin D , and because vitamin D promotes intestinal absorption of calcium , PTH indirectly increases calcium uptake by the small intestine . <hl> Calcitonin , a hormone secreted by the thyroid gland , has some effects that counteract those of PTH . <hl> Calcitonin inhibits osteoclast activity and stimulates calcium uptake by the bones , thus reducing the concentration of calcium ions in the blood . As evidenced by their opposing functions in maintaining calcium homeostasis , PTH and calcitonin are generally not secreted at the same time . Table 6.6 summarizes the hormones that influence the skeletal system . Bone modeling and remodeling require osteoclasts to resorb unneeded , damaged , or old bone , and osteoblasts to lay down new bone . <hl> Two hormones that affect the osteoclasts are parathyroid hormone ( PTH ) and calcitonin . <hl>", "hl_sentences": "Calcitonin , a hormone secreted by the thyroid gland , has some effects that counteract those of PTH . Two hormones that affect the osteoclasts are parathyroid hormone ( PTH ) and calcitonin .", "question": { "cloze_format": "With respect to their direct effects on osseous tissue, the pair of hormones that has actions that oppose each other is ___.", "normal_format": "With respect to their direct effects on osseous tissue, which pair of hormones has actions that oppose each other?", "question_choices": [ "estrogen and testosterone", "calcitonin and calcitriol", "estrogen and progesterone", "calcitonin and parathyroid hormone" ], "question_id": "fs-id704483", "question_text": "With respect to their direct effects on osseous tissue, which pair of hormones has actions that oppose each other?" }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 3, "ans_text": "nervous system" }, "bloom": "1", "hl_context": "<hl> Conversely , in hypercalcemia , a condition characterized by abnormally high levels of calcium , the nervous system is underactive , which results in lethargy , sluggish reflexes , constipation and loss of appetite , confusion , and in severe cases , coma . <hl>", "hl_sentences": "Conversely , in hypercalcemia , a condition characterized by abnormally high levels of calcium , the nervous system is underactive , which results in lethargy , sluggish reflexes , constipation and loss of appetite , confusion , and in severe cases , coma .", "question": { "cloze_format": "When calcium levels are too high or too low, the body system that is primarily affected is the ___ .", "normal_format": "When calcium levels are too high or too low, which body system is primarily affected?", "question_choices": [ "skeletal system", "endocrine system", "digestive system", "nervous system" ], "question_id": "fs-id1284795", "question_text": "When calcium levels are too high or too low, which body system is primarily affected?" }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 0, "ans_text": "thyroxine" }, "bloom": "1", "hl_context": "<hl> Stimulates bone growth and promotes synthesis of bone matrix <hl> <hl> Thyroxine <hl> The small intestine is also affected by PTH , albeit indirectly . <hl> Because another function of PTH is to stimulate the synthesis of vitamin D , and because vitamin D promotes intestinal absorption of calcium , PTH indirectly increases calcium uptake by the small intestine . <hl> <hl> Calcitonin , a hormone secreted by the thyroid gland , has some effects that counteract those of PTH . <hl> Calcitonin inhibits osteoclast activity and stimulates calcium uptake by the bones , thus reducing the concentration of calcium ions in the blood . <hl> As evidenced by their opposing functions in maintaining calcium homeostasis , PTH and calcitonin are generally not secreted at the same time . <hl> Table 6.6 summarizes the hormones that influence the skeletal system . PTH stimulates osteoclast proliferation and activity . As a result , calcium is released from the bones into the circulation , thus increasing the calcium ion concentration in the blood . <hl> PTH also promotes the reabsorption of calcium by the kidney tubules , which can affect calcium homeostasis ( see below ) . <hl>", "hl_sentences": "Stimulates bone growth and promotes synthesis of bone matrix Thyroxine Because another function of PTH is to stimulate the synthesis of vitamin D , and because vitamin D promotes intestinal absorption of calcium , PTH indirectly increases calcium uptake by the small intestine . Calcitonin , a hormone secreted by the thyroid gland , has some effects that counteract those of PTH . As evidenced by their opposing functions in maintaining calcium homeostasis , PTH and calcitonin are generally not secreted at the same time . PTH also promotes the reabsorption of calcium by the kidney tubules , which can affect calcium homeostasis ( see below ) .", "question": { "cloze_format": "___ does not play a role in calcium homeostasis.", "normal_format": "All of the following play a role in calcium homeostasis except which one?", "question_choices": [ "thyroxine", "calcitonin", "parathyroid hormone", "vitamin D" ], "question_id": "fs-id1829377", "question_text": "All of the following play a role in calcium homeostasis except" }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 1, "ans_text": "calcitonin" }, "bloom": "1", "hl_context": "<hl> When blood levels of calcium get too high , the thyroid gland is stimulated to release calcitonin ( Figure 6.24 ) , which inhibits osteoclast activity and stimulates calcium uptake by the bones , but also decreases reabsorption of calcium by the kidneys . <hl> All of these actions lower blood levels of calcium . When blood calcium levels return to normal , the thyroid gland stops secreting calcitonin .", "hl_sentences": "When blood levels of calcium get too high , the thyroid gland is stimulated to release calcitonin ( Figure 6.24 ) , which inhibits osteoclast activity and stimulates calcium uptake by the bones , but also decreases reabsorption of calcium by the kidneys .", "question": { "cloze_format": "___ is most likely to be released when blood calcium levels are elevated.", "normal_format": "Which of the following is most likely to be released when blood calcium levels are elevated?", "question_choices": [ "thyroxine", "calcitonin", "parathyroid hormone", "vitamin D" ], "question_id": "fs-id1804706", "question_text": "Which of the following is most likely to be released when blood calcium levels are elevated?" }, "references_are_paraphrase": null } ]
6
6.1 The Functions of the Skeletal System Learning Objectives By the end of this section, you will be able to: Define bone, cartilage, and the skeletal system List and describe the functions of the skeletal system Bone , or osseous tissue , is a hard, dense connective tissue that forms most of the adult skeleton, the support structure of the body. In the areas of the skeleton where bones move (for example, the ribcage and joints), cartilage , a semi-rigid form of connective tissue, provides flexibility and smooth surfaces for movement. The skeletal system is the body system composed of bones and cartilage and performs the following critical functions for the human body: supports the body facilitates movement protects internal organs produces blood cells stores and releases minerals and fat Support, Movement, and Protection The most apparent functions of the skeletal system are the gross functions—those visible by observation. Simply by looking at a person, you can see how the bones support, facilitate movement, and protect the human body. Just as the steel beams of a building provide a scaffold to support its weight, the bones and cartilage of your skeletal system compose the scaffold that supports the rest of your body. Without the skeletal system, you would be a limp mass of organs, muscle, and skin. Bones also facilitate movement by serving as points of attachment for your muscles. While some bones only serve as a support for the muscles, others also transmit the forces produced when your muscles contract. From a mechanical point of view, bones act as levers and joints serve as fulcrums ( Figure 6.2 ). Unless a muscle spans a joint and contracts, a bone is not going to move. For information on the interaction of the skeletal and muscular systems, that is, the musculoskeletal system, seek additional content. Bones also protect internal organs from injury by covering or surrounding them. For example, your ribs protect your lungs and heart, the bones of your vertebral column (spine) protect your spinal cord, and the bones of your cranium (skull) protect your brain ( Figure 6.3 ). Career Connection Orthopedist An orthopedist is a doctor who specializes in diagnosing and treating disorders and injuries related to the musculoskeletal system. Some orthopedic problems can be treated with medications, exercises, braces, and other devices, but others may be best treated with surgery ( Figure 6.4 ). While the origin of the word “orthopedics” (ortho- = “straight”; paed- = “child”), literally means “straightening of the child,” orthopedists can have patients who range from pediatric to geriatric. In recent years, orthopedists have even performed prenatal surgery to correct spina bifida, a congenital defect in which the neural canal in the spine of the fetus fails to close completely during embryologic development. Orthopedists commonly treat bone and joint injuries but they also treat other bone conditions including curvature of the spine. Lateral curvatures (scoliosis) can be severe enough to slip under the shoulder blade (scapula) forcing it up as a hump. Spinal curvatures can also be excessive dorsoventrally (kyphosis) causing a hunch back and thoracic compression. These curvatures often appear in preteens as the result of poor posture, abnormal growth, or indeterminate causes. Mostly, they are readily treated by orthopedists. As people age, accumulated spinal column injuries and diseases like osteoporosis can also lead to curvatures of the spine, hence the stooping you sometimes see in the elderly. Some orthopedists sub-specialize in sports medicine, which addresses both simple injuries, such as a sprained ankle, and complex injuries, such as a torn rotator cuff in the shoulder. Treatment can range from exercise to surgery. Mineral Storage, Energy Storage, and Hematopoiesis On a metabolic level, bone tissue performs several critical functions. For one, the bone matrix acts as a reservoir for a number of minerals important to the functioning of the body, especially calcium, and phosphorus. These minerals, incorporated into bone tissue, can be released back into the bloodstream to maintain levels needed to support physiological processes. Calcium ions, for example, are essential for muscle contractions and controlling the flow of other ions involved in the transmission of nerve impulses. Bone also serves as a site for fat storage and blood cell production. The softer connective tissue that fills the interior of most bone is referred to as bone marrow ( Figure 6.5 ). There are two types of bone marrow: yellow marrow and red marrow. Yellow marrow contains adipose tissue; the triglycerides stored in the adipocytes of the tissue can serve as a source of energy. Red marrow is where hematopoiesis —the production of blood cells—takes place. Red blood cells, white blood cells, and platelets are all produced in the red marrow. 6.2 Bone Classification Learning Objectives By the end of this section, you will be able to: Classify bones according to their shapes Describe the function of each category of bones The 206 bones that compose the adult skeleton are divided into five categories based on their shapes ( Figure 6.6 ). Their shapes and their functions are related such that each categorical shape of bone has a distinct function. Long Bones A long bone is one that is cylindrical in shape, being longer than it is wide. Keep in mind, however, that the term describes the shape of a bone, not its size. Long bones are found in the arms (humerus, ulna, radius) and legs (femur, tibia, fibula), as well as in the fingers (metacarpals, phalanges) and toes (metatarsals, phalanges). Long bones function as levers; they move when muscles contract. Short Bones A short bone is one that is cube-like in shape, being approximately equal in length, width, and thickness. The only short bones in the human skeleton are in the carpals of the wrists and the tarsals of the ankles. Short bones provide stability and support as well as some limited motion. Flat Bones The term “ flat bone ” is somewhat of a misnomer because, although a flat bone is typically thin, it is also often curved. Examples include the cranial (skull) bones, the scapulae (shoulder blades), the sternum (breastbone), and the ribs. Flat bones serve as points of attachment for muscles and often protect internal organs. Irregular Bones An irregular bone is one that does not have any easily characterized shape and therefore does not fit any other classification. These bones tend to have more complex shapes, like the vertebrae that support the spinal cord and protect it from compressive forces. Many facial bones, particularly the ones containing sinuses, are classified as irregular bones. Sesamoid Bones A sesamoid bone is a small, round bone that, as the name suggests, is shaped like a sesame seed. These bones form in tendons (the sheaths of tissue that connect bones to muscles) where a great deal of pressure is generated in a joint. The sesamoid bones protect tendons by helping them overcome compressive forces. Sesamoid bones vary in number and placement from person to person but are typically found in tendons associated with the feet, hands, and knees. The patellae (singular = patella) are the only sesamoid bones found in common with every person. Table 6.1 reviews bone classifications with their associated features, functions, and examples. Bone Classifications Bone classification Features Function(s) Examples Long Cylinder-like shape, longer than it is wide Leverage Femur, tibia, fibula, metatarsals, humerus, ulna, radius, metacarpals, phalanges Short Cube-like shape, approximately equal in length, width, and thickness Provide stability, support, while allowing for some motion Carpals, tarsals Flat Thin and curved Points of attachment for muscles; protectors of internal organs Sternum, ribs, scapulae, cranial bones Irregular Complex shape Protect internal organs Vertebrae, facial bones Sesamoid Small and round; embedded in tendons Protect tendons from compressive forces Patellae Table 6.1 6.3 Bone Structure Learning Objectives By the end of this section, you will be able to: Identify the anatomical features of a bone Define and list examples of bone markings Describe the histology of bone tissue Compare and contrast compact and spongy bone Identify the structures that compose compact and spongy bone Describe how bones are nourished and innervated Bone tissue (osseous tissue) differs greatly from other tissues in the body. Bone is hard and many of its functions depend on that characteristic hardness. Later discussions in this chapter will show that bone is also dynamic in that its shape adjusts to accommodate stresses. This section will examine the gross anatomy of bone first and then move on to its histology. Gross Anatomy of Bone The structure of a long bone allows for the best visualization of all of the parts of a bone ( Figure 6.7 ). A long bone has two parts: the diaphysis and the epiphysis . The diaphysis is the tubular shaft that runs between the proximal and distal ends of the bone. The hollow region in the diaphysis is called the medullary cavity , which is filled with yellow marrow. The walls of the diaphysis are composed of dense and hard compact bone . The wider section at each end of the bone is called the epiphysis (plural = epiphyses), which is filled with spongy bone. Red marrow fills the spaces in the spongy bone. Each epiphysis meets the diaphysis at the metaphysis, the narrow area that contains the epiphyseal plate (growth plate), a layer of hyaline (transparent) cartilage in a growing bone. When the bone stops growing in early adulthood (approximately 18–21 years), the cartilage is replaced by osseous tissue and the epiphyseal plate becomes an epiphyseal line. The medullary cavity has a delicate membranous lining called the endosteum (end- = “inside”; oste- = “bone”), where bone growth, repair, and remodeling occur. The outer surface of the bone is covered with a fibrous membrane called the periosteum (peri - = “around” or “surrounding”). The periosteum contains blood vessels, nerves, and lymphatic vessels that nourish compact bone. Tendons and ligaments also attach to bones at the periosteum. The periosteum covers the entire outer surface except where the epiphyses meet other bones to form joints ( Figure 6.8 ). In this region, the epiphyses are covered with articular cartilage , a thin layer of cartilage that reduces friction and acts as a shock absorber. Flat bones, like those of the cranium, consist of a layer of diploë (spongy bone), lined on either side by a layer of compact bone ( Figure 6.9 ). The two layers of compact bone and the interior spongy bone work together to protect the internal organs. If the outer layer of a cranial bone fractures, the brain is still protected by the intact inner layer. Bone Markings The surface features of bones vary considerably, depending on the function and location in the body. Table 6.2 describes the bone markings, which are illustrated in ( Figure 6.10 ). There are three general classes of bone markings: (1) articulations, (2) projections, and (3) holes. As the name implies, an articulation is where two bone surfaces come together (articulus = “joint”). These surfaces tend to conform to one another, such as one being rounded and the other cupped, to facilitate the function of the articulation. A projection is an area of a bone that projects above the surface of the bone. These are the attachment points for tendons and ligaments. In general, their size and shape is an indication of the forces exerted through the attachment to the bone. A hole is an opening or groove in the bone that allows blood vessels and nerves to enter the bone. As with the other markings, their size and shape reflect the size of the vessels and nerves that penetrate the bone at these points. Bone Markings Marking Description Example Articulations Where two bones meet Knee joint Head Prominent rounded surface Head of femur Facet Flat surface Vertebrae Condyle Rounded surface Occipital condyles Projections Raised markings Spinous process of the vertebrae Protuberance Protruding Chin Process Prominence feature Transverse process of vertebra Spine Sharp process Ischial spine Tubercle Small, rounded process Tubercle of humerus Tuberosity Rough surface Deltoid tuberosity Line Slight, elongated ridge Temporal lines of the parietal bones Crest Ridge Iliac crest Holes Holes and depressions Foramen (holes through which blood vessels can pass through) Fossa Elongated basin Mandibular fossa Fovea Small pit Fovea capitis on the head of the femur Sulcus Groove Sigmoid sulcus of the temporal bones Canal Passage in bone Auditory canal Fissure Slit through bone Auricular fissure Foramen Hole through bone Foramen magnum in the occipital bone Meatus Opening into canal External auditory meatus Sinus Air-filled space in bone Nasal sinus Table 6.2 Bone Cells and Tissue Bone contains a relatively small number of cells entrenched in a matrix of collagen fibers that provide a surface for inorganic salt crystals to adhere. These salt crystals form when calcium phosphate and calcium carbonate combine to create hydroxyapatite, which incorporates other inorganic salts like magnesium hydroxide, fluoride, and sulfate as it crystallizes, or calcifies, on the collagen fibers. The hydroxyapatite crystals give bones their hardness and strength, while the collagen fibers give them flexibility so that they are not brittle. Although bone cells compose a small amount of the bone volume, they are crucial to the function of bones. Four types of cells are found within bone tissue: osteoblasts, osteocytes, osteogenic cells, and osteoclasts ( Figure 6.11 ). The osteoblast is the bone cell responsible for forming new bone and is found in the growing portions of bone, including the periosteum and endosteum. Osteoblasts, which do not divide, synthesize and secrete the collagen matrix and calcium salts. As the secreted matrix surrounding the osteoblast calcifies, the osteoblast become trapped within it; as a result, it changes in structure and becomes an osteocyte , the primary cell of mature bone and the most common type of bone cell. Each osteocyte is located in a space called a lacuna and is surrounded by bone tissue. Osteocytes maintain the mineral concentration of the matrix via the secretion of enzymes. Like osteoblasts, osteocytes lack mitotic activity. They can communicate with each other and receive nutrients via long cytoplasmic processes that extend through canaliculi (singular = canaliculus), channels within the bone matrix. If osteoblasts and osteocytes are incapable of mitosis, then how are they replenished when old ones die? The answer lies in the properties of a third category of bone cells—the osteogenic cell . These osteogenic cells are undifferentiated with high mitotic activity and they are the only bone cells that divide. Immature osteogenic cells are found in the deep layers of the periosteum and the marrow. They differentiate and develop into osteoblasts. The dynamic nature of bone means that new tissue is constantly formed, and old, injured, or unnecessary bone is dissolved for repair or for calcium release. The cell responsible for bone resorption, or breakdown, is the osteoclast . They are found on bone surfaces, are multinucleated, and originate from monocytes and macrophages, two types of white blood cells, not from osteogenic cells. Osteoclasts are continually breaking down old bone while osteoblasts are continually forming new bone. The ongoing balance between osteoblasts and osteoclasts is responsible for the constant but subtle reshaping of bone. Table 6.3 reviews the bone cells, their functions, and locations. Bone Cells Cell type Function Location Osteogenic cells Develop into osteoblasts Deep layers of the periosteum and the marrow Osteoblasts Bone formation Growing portions of bone, including periosteum and endosteum Osteocytes Maintain mineral concentration of matrix Entrapped in matrix Osteoclasts Bone resorption Bone surfaces and at sites of old, injured, or unneeded bone Table 6.3 Compact and Spongy Bone The differences between compact and spongy bone are best explored via their histology. Most bones contain compact and spongy osseous tissue, but their distribution and concentration vary based on the bone’s overall function. Compact bone is dense so that it can withstand compressive forces, while spongy (cancellous) bone has open spaces and supports shifts in weight distribution. Compact Bone Compact bone is the denser, stronger of the two types of bone tissue ( Figure 6.12 ). It can be found under the periosteum and in the diaphyses of long bones, where it provides support and protection. The microscopic structural unit of compact bone is called an osteon , or Haversian system. Each osteon is composed of concentric rings of calcified matrix called lamellae (singular = lamella). Running down the center of each osteon is the central canal , or Haversian canal, which contains blood vessels, nerves, and lymphatic vessels. These vessels and nerves branch off at right angles through a perforating canal , also known as Volkmann’s canals, to extend to the periosteum and endosteum. The osteocytes are located inside spaces called lacunae (singular = lacuna), found at the borders of adjacent lamellae. As described earlier, canaliculi connect with the canaliculi of other lacunae and eventually with the central canal. This system allows nutrients to be transported to the osteocytes and wastes to be removed from them. Spongy (Cancellous) Bone Like compact bone, spongy bone , also known as cancellous bone, contains osteocytes housed in lacunae, but they are not arranged in concentric circles. Instead, the lacunae and osteocytes are found in a lattice-like network of matrix spikes called trabeculae (singular = trabecula) ( Figure 6.13 ). The trabeculae may appear to be a random network, but each trabecula forms along lines of stress to provide strength to the bone. The spaces of the trabeculated network provide balance to the dense and heavy compact bone by making bones lighter so that muscles can move them more easily. In addition, the spaces in some spongy bones contain red marrow, protected by the trabeculae, where hematopoiesis occurs. Aging and the... Skeletal System: Paget’s Disease Paget’s disease usually occurs in adults over age 40. It is a disorder of the bone remodeling process that begins with overactive osteoclasts. This means more bone is resorbed than is laid down. The osteoblasts try to compensate but the new bone they lay down is weak and brittle and therefore prone to fracture. While some people with Paget’s disease have no symptoms, others experience pain, bone fractures, and bone deformities ( Figure 6.14 ). Bones of the pelvis, skull, spine, and legs are the most commonly affected. When occurring in the skull, Paget’s disease can cause headaches and hearing loss. What causes the osteoclasts to become overactive? The answer is still unknown, but hereditary factors seem to play a role. Some scientists believe Paget’s disease is due to an as-yet-unidentified virus. Paget’s disease is diagnosed via imaging studies and lab tests. X-rays may show bone deformities or areas of bone resorption. Bone scans are also useful. In these studies, a dye containing a radioactive ion is injected into the body. Areas of bone resorption have an affinity for the ion, so they will light up on the scan if the ions are absorbed. In addition, blood levels of an enzyme called alkaline phosphatase are typically elevated in people with Paget’s disease. Bisphosphonates, drugs that decrease the activity of osteoclasts, are often used in the treatment of Paget’s disease. However, in a small percentage of cases, bisphosphonates themselves have been linked to an increased risk of fractures because the old bone that is left after bisphosphonates are administered becomes worn out and brittle. Still, most doctors feel that the benefits of bisphosphonates more than outweigh the risk; the medical professional has to weigh the benefits and risks on a case-by-case basis. Bisphosphonate treatment can reduce the overall risk of deformities or fractures, which in turn reduces the risk of surgical repair and its associated risks and complications. Blood and Nerve Supply The spongy bone and medullary cavity receive nourishment from arteries that pass through the compact bone. The arteries enter through the nutrient foramen (plural = foramina), small openings in the diaphysis ( Figure 6.15 ). The osteocytes in spongy bone are nourished by blood vessels of the periosteum that penetrate spongy bone and blood that circulates in the marrow cavities. As the blood passes through the marrow cavities, it is collected by veins, which then pass out of the bone through the foramina. In addition to the blood vessels, nerves follow the same paths into the bone where they tend to concentrate in the more metabolically active regions of the bone. The nerves sense pain, and it appears the nerves also play roles in regulating blood supplies and in bone growth, hence their concentrations in metabolically active sites of the bone. Interactive Link Watch this video to see the microscopic features of a bone. 6.4 Bone Formation and Development Learning Objectives By the end of this section, you will be able to: Explain the function of cartilage List the steps of intramembranous ossification List the steps of endochondral ossification Explain the growth activity at the epiphyseal plate Compare and contrast the processes of modeling and remodeling In the early stages of embryonic development, the embryo’s skeleton consists of fibrous membranes and hyaline cartilage. By the sixth or seventh week of embryonic life, the actual process of bone development, ossification (osteogenesis), begins. There are two osteogenic pathways—intramembranous ossification and endochondral ossification—but bone is the same regardless of the pathway that produces it. Cartilage Templates Bone is a replacement tissue; that is, it uses a model tissue on which to lay down its mineral matrix. For skeletal development, the most common template is cartilage. During fetal development, a framework is laid down that determines where bones will form. This framework is a flexible, semi-solid matrix produced by chondroblasts and consists of hyaluronic acid, chondroitin sulfate, collagen fibers, and water. As the matrix surrounds and isolates chondroblasts, they are called chondrocytes. Unlike most connective tissues, cartilage is avascular, meaning that it has no blood vessels supplying nutrients and removing metabolic wastes. All of these functions are carried on by diffusion through the matrix. This is why damaged cartilage does not repair itself as readily as most tissues do. Throughout fetal development and into childhood growth and development, bone forms on the cartilaginous matrix. By the time a fetus is born, most of the cartilage has been replaced with bone. Some additional cartilage will be replaced throughout childhood, and some cartilage remains in the adult skeleton. Intramembranous Ossification During intramembranous ossification , compact and spongy bone develops directly from sheets of mesenchymal (undifferentiated) connective tissue. The flat bones of the face, most of the cranial bones, and the clavicles (collarbones) are formed via intramembranous ossification. The process begins when mesenchymal cells in the embryonic skeleton gather together and begin to differentiate into specialized cells ( Figure 6.16 a ). Some of these cells will differentiate into capillaries, while others will become osteogenic cells and then osteoblasts. Although they will ultimately be spread out by the formation of bone tissue, early osteoblasts appear in a cluster called an ossification center . The osteoblasts secrete osteoid , uncalcified matrix, which calcifies (hardens) within a few days as mineral salts are deposited on it, thereby entrapping the osteoblasts within. Once entrapped, the osteoblasts become osteocytes ( Figure 6.16 b ). As osteoblasts transform into osteocytes, osteogenic cells in the surrounding connective tissue differentiate into new osteoblasts. Osteoid (unmineralized bone matrix) secreted around the capillaries results in a trabecular matrix, while osteoblasts on the surface of the spongy bone become the periosteum ( Figure 6.16 c ). The periosteum then creates a protective layer of compact bone superficial to the trabecular bone. The trabecular bone crowds nearby blood vessels, which eventually condense into red marrow ( Figure 6.16 d ). Intramembranous ossification begins in utero during fetal development and continues on into adolescence. At birth, the skull and clavicles are not fully ossified nor are the sutures of the skull closed. This allows the skull and shoulders to deform during passage through the birth canal. The last bones to ossify via intramembranous ossification are the flat bones of the face, which reach their adult size at the end of the adolescent growth spurt. Endochondral Ossification In endochondral ossification , bone develops by replacing hyaline cartilage. Cartilage does not become bone. Instead, cartilage serves as a template to be completely replaced by new bone. Endochondral ossification takes much longer than intramembranous ossification. Bones at the base of the skull and long bones form via endochondral ossification. In a long bone, for example, at about 6 to 8 weeks after conception, some of the mesenchymal cells differentiate into chondrocytes (cartilage cells) that form the cartilaginous skeletal precursor of the bones ( Figure 6.17 a ). Soon after, the perichondrium , a membrane that covers the cartilage, appears Figure 6.17 b ). As more matrix is produced, the chondrocytes in the center of the cartilaginous model grow in size. As the matrix calcifies, nutrients can no longer reach the chondrocytes. This results in their death and the disintegration of the surrounding cartilage. Blood vessels invade the resulting spaces, not only enlarging the cavities but also carrying osteogenic cells with them, many of which will become osteoblasts. These enlarging spaces eventually combine to become the medullary cavity. As the cartilage grows, capillaries penetrate it. This penetration initiates the transformation of the perichondrium into the bone-producing periosteum. Here, the osteoblasts form a periosteal collar of compact bone around the cartilage of the diaphysis. By the second or third month of fetal life, bone cell development and ossification ramps up and creates the primary ossification center , a region deep in the periosteal collar where ossification begins ( Figure 6.17 c ). While these deep changes are occurring, chondrocytes and cartilage continue to grow at the ends of the bone (the future epiphyses), which increases the bone’s length at the same time bone is replacing cartilage in the diaphyses. By the time the fetal skeleton is fully formed, cartilage only remains at the joint surface as articular cartilage and between the diaphysis and epiphysis as the epiphyseal plate, the latter of which is responsible for the longitudinal growth of bones. After birth, this same sequence of events (matrix mineralization, death of chondrocytes, invasion of blood vessels from the periosteum, and seeding with osteogenic cells that become osteoblasts) occurs in the epiphyseal regions, and each of these centers of activity is referred to as a secondary ossification center ( Figure 6.17 e ). How Bones Grow in Length The epiphyseal plate is the area of growth in a long bone. It is a layer of hyaline cartilage where ossification occurs in immature bones. On the epiphyseal side of the epiphyseal plate, cartilage is formed. On the diaphyseal side, cartilage is ossified, and the diaphysis grows in length. The epiphyseal plate is composed of four zones of cells and activity ( Figure 6.18 ). The reserve zone is the region closest to the epiphyseal end of the plate and contains small chondrocytes within the matrix. These chondrocytes do not participate in bone growth but secure the epiphyseal plate to the osseous tissue of the epiphysis. The proliferative zone is the next layer toward the diaphysis and contains stacks of slightly larger chondrocytes. It makes new chondrocytes (via mitosis) to replace those that die at the diaphyseal end of the plate. Chondrocytes in the next layer, the zone of maturation and hypertrophy , are older and larger than those in the proliferative zone. The more mature cells are situated closer to the diaphyseal end of the plate. The longitudinal growth of bone is a result of cellular division in the proliferative zone and the maturation of cells in the zone of maturation and hypertrophy. Most of the chondrocytes in the zone of calcified matrix , the zone closest to the diaphysis, are dead because the matrix around them has calcified. Capillaries and osteoblasts from the diaphysis penetrate this zone, and the osteoblasts secrete bone tissue on the remaining calcified cartilage. Thus, the zone of calcified matrix connects the epiphyseal plate to the diaphysis. A bone grows in length when osseous tissue is added to the diaphysis. Bones continue to grow in length until early adulthood. The rate of growth is controlled by hormones, which will be discussed later. When the chondrocytes in the epiphyseal plate cease their proliferation and bone replaces the cartilage, longitudinal growth stops. All that remains of the epiphyseal plate is the epiphyseal line ( Figure 6.19 ). How Bones Grow in Diameter While bones are increasing in length, they are also increasing in diameter; growth in diameter can continue even after longitudinal growth ceases. This is called appositional growth. Osteoclasts resorb old bone that lines the medullary cavity, while osteoblasts, via intramembranous ossification, produce new bone tissue beneath the periosteum. The erosion of old bone along the medullary cavity and the deposition of new bone beneath the periosteum not only increase the diameter of the diaphysis but also increase the diameter of the medullary cavity. This process is called modeling . Bone Remodeling The process in which matrix is resorbed on one surface of a bone and deposited on another is known as bone modeling. Modeling primarily takes place during a bone’s growth. However, in adult life, bone undergoes remodeling , in which resorption of old or damaged bone takes place on the same surface where osteoblasts lay new bone to replace that which is resorbed. Injury, exercise, and other activities lead to remodeling. Those influences are discussed later in the chapter, but even without injury or exercise, about 5 to 10 percent of the skeleton is remodeled annually just by destroying old bone and renewing it with fresh bone. Diseases of the... Skeletal System Osteogenesis imperfecta (OI) is a genetic disease in which bones do not form properly and therefore are fragile and break easily. It is also called brittle bone disease. The disease is present from birth and affects a person throughout life. The genetic mutation that causes OI affects the body’s production of collagen, one of the critical components of bone matrix. The severity of the disease can range from mild to severe. Those with the most severe forms of the disease sustain many more fractures than those with a mild form. Frequent and multiple fractures typically lead to bone deformities and short stature. Bowing of the long bones and curvature of the spine are also common in people afflicted with OI. Curvature of the spine makes breathing difficult because the lungs are compressed. Because collagen is such an important structural protein in many parts of the body, people with OI may also experience fragile skin, weak muscles, loose joints, easy bruising, frequent nosebleeds, brittle teeth, blue sclera, and hearing loss. There is no known cure for OI. Treatment focuses on helping the person retain as much independence as possible while minimizing fractures and maximizing mobility. Toward that end, safe exercises, like swimming, in which the body is less likely to experience collisions or compressive forces, are recommended. Braces to support legs, ankles, knees, and wrists are used as needed. Canes, walkers, or wheelchairs can also help compensate for weaknesses. When bones do break, casts, splints, or wraps are used. In some cases, metal rods may be surgically implanted into the long bones of the arms and legs. Research is currently being conducted on using bisphosphonates to treat OI. Smoking and being overweight are especially risky in people with OI, since smoking is known to weaken bones, and extra body weight puts additional stress on the bones. Interactive Link Watch this video to see how a bone grows. 6.5 Fractures: Bone Repair Learning Objectives By the end of this section, you will be able to: Differentiate among the different types of fractures Describe the steps involved in bone repair A fracture is a broken bone. It will heal whether or not a physician resets it in its anatomical position. If the bone is not reset correctly, the healing process will keep the bone in its deformed position. When a broken bone is manipulated and set into its natural position without surgery, the procedure is called a closed reduction . Open reduction requires surgery to expose the fracture and reset the bone. While some fractures can be minor, others are quite severe and result in grave complications. For example, a fractured diaphysis of the femur has the potential to release fat globules into the bloodstream. These can become lodged in the capillary beds of the lungs, leading to respiratory distress and if not treated quickly, death. Types of Fractures Fractures are classified by their complexity, location, and other features ( Figure 6.20 ). Table 6.4 outlines common types of fractures. Some fractures may be described using more than one term because it may have the features of more than one type (e.g., an open transverse fracture). Types of Fractures Type of fracture Description Transverse Occurs straight across the long axis of the bone Oblique Occurs at an angle that is not 90 degrees Spiral Bone segments are pulled apart as a result of a twisting motion Comminuted Several breaks result in many small pieces between two large segments Impacted One fragment is driven into the other, usually as a result of compression Greenstick A partial fracture in which only one side of the bone is broken Open (or compound) A fracture in which at least one end of the broken bone tears through the skin; carries a high risk of infection Closed (or simple) A fracture in which the skin remains intact Table 6.4 Bone Repair When a bone breaks, blood flows from any vessel torn by the fracture. These vessels could be in the periosteum, osteons, and/or medullary cavity. The blood begins to clot, and about six to eight hours after the fracture, the clotting blood has formed a fracture hematoma ( Figure 6.21 a ). The disruption of blood flow to the bone results in the death of bone cells around the fracture. Within about 48 hours after the fracture, chondrocytes from the endosteum have created an internal callus (plural = calli) by secreting a fibrocartilaginous matrix between the two ends of the broken bone, while the periosteal chondrocytes and osteoblasts create an external callus of hyaline cartilage and bone, respectively, around the outside of the break ( Figure 6.21 b ). This stabilizes the fracture. Over the next several weeks, osteoclasts resorb the dead bone; osteogenic cells become active, divide, and differentiate into osteoblasts. The cartilage in the calli is replaced by trabecular bone via endochondral ossification ( Figure 6.21 c ). Eventually, the internal and external calli unite, compact bone replaces spongy bone at the outer margins of the fracture, and healing is complete. A slight swelling may remain on the outer surface of the bone, but quite often, that region undergoes remodeling ( Figure 6.21 d ), and no external evidence of the fracture remains. Interactive Link Visit this website to review different types of fractures and then take a short self-assessment quiz. 6.6 Exercise, Nutrition, Hormones, and Bone Tissue Learning Objectives By the end of this section, you will be able to: Describe the effect exercise has on bone tissue List the nutrients that affect bone health Discuss the role those nutrients play in bone health Describe the effects of hormones on bone tissue All of the organ systems of your body are interdependent, and the skeletal system is no exception. The food you take in via your digestive system and the hormones secreted by your endocrine system affect your bones. Even using your muscles to engage in exercise has an impact on your bones. Exercise and Bone Tissue During long space missions, astronauts can lose approximately 1 to 2 percent of their bone mass per month. This loss of bone mass is thought to be caused by the lack of mechanical stress on astronauts’ bones due to the low gravitational forces in space. Lack of mechanical stress causes bones to lose mineral salts and collagen fibers, and thus strength. Similarly, mechanical stress stimulates the deposition of mineral salts and collagen fibers. The internal and external structure of a bone will change as stress increases or decreases so that the bone is an ideal size and weight for the amount of activity it endures. That is why people who exercise regularly have thicker bones than people who are more sedentary. It is also why a broken bone in a cast atrophies while its contralateral mate maintains its concentration of mineral salts and collagen fibers. The bones undergo remodeling as a result of forces (or lack of forces) placed on them. Numerous, controlled studies have demonstrated that people who exercise regularly have greater bone density than those who are more sedentary. Any type of exercise will stimulate the deposition of more bone tissue, but resistance training has a greater effect than cardiovascular activities. Resistance training is especially important to slow down the eventual bone loss due to aging and for preventing osteoporosis. Nutrition and Bone Tissue The vitamins and minerals contained in all of the food we consume are important for all of our organ systems. However, there are certain nutrients that affect bone health. Calcium and Vitamin D You already know that calcium is a critical component of bone, especially in the form of calcium phosphate and calcium carbonate. Since the body cannot make calcium, it must be obtained from the diet. However, calcium cannot be absorbed from the small intestine without vitamin D. Therefore, intake of vitamin D is also critical to bone health. In addition to vitamin D’s role in calcium absorption, it also plays a role, though not as clearly understood, in bone remodeling. Milk and other dairy foods are not the only sources of calcium. This important nutrient is also found in green leafy vegetables, broccoli, and intact salmon and canned sardines with their soft bones. Nuts, beans, seeds, and shellfish provide calcium in smaller quantities. Except for fatty fish like salmon and tuna, or fortified milk or cereal, vitamin D is not found naturally in many foods. The action of sunlight on the skin triggers the body to produce its own vitamin D ( Figure 6.22 ), but many people, especially those of darker complexion and those living in northern latitudes where the sun’s rays are not as strong, are deficient in vitamin D. In cases of deficiency, a doctor can prescribe a vitamin D supplement. Other Nutrients Vitamin K also supports bone mineralization and may have a synergistic role with vitamin D in the regulation of bone growth. Green leafy vegetables are a good source of vitamin K. The minerals magnesium and fluoride may also play a role in supporting bone health. While magnesium is only found in trace amounts in the human body, more than 60 percent of it is in the skeleton, suggesting it plays a role in the structure of bone. Fluoride can displace the hydroxyl group in bone’s hydroxyapatite crystals and form fluorapatite. Similar to its effect on dental enamel, fluorapatite helps stabilize and strengthen bone mineral. Fluoride can also enter spaces within hydroxyapatite crystals, thus increasing their density. Omega-3 fatty acids have long been known to reduce inflammation in various parts of the body. Inflammation can interfere with the function of osteoblasts, so consuming omega-3 fatty acids, in the diet or in supplements, may also help enhance production of new osseous tissue. Table 6.5 summarizes the role of nutrients in bone health. Nutrients and Bone Health Nutrient Role in bone health Calcium Needed to make calcium phosphate and calcium carbonate, which form the hydroxyapatite crystals that give bone its hardness Vitamin D Needed for calcium absorption Vitamin K Supports bone mineralization; may have synergistic effect with vitamin D Magnesium Structural component of bone Fluoride Structural component of bone Omega-3 fatty acids Reduces inflammation that may interfere with osteoblast function Table 6.5 Hormones and Bone Tissue The endocrine system produces and secretes hormones, many of which interact with the skeletal system. These hormones are involved in controlling bone growth, maintaining bone once it is formed, and remodeling it. Hormones That Influence Osteoblasts and/or Maintain the Matrix Several hormones are necessary for controlling bone growth and maintaining the bone matrix. The pituitary gland secretes growth hormone (GH), which, as its name implies, controls bone growth in several ways. It triggers chondrocyte proliferation in epiphyseal plates, resulting in the increasing length of long bones. GH also increases calcium retention, which enhances mineralization, and stimulates osteoblastic activity, which improves bone density. GH is not alone in stimulating bone growth and maintaining osseous tissue. Thyroxine, a hormone secreted by the thyroid gland promotes osteoblastic activity and the synthesis of bone matrix. During puberty, the sex hormones (estrogen in girls, testosterone in boys) also come into play. They too promote osteoblastic activity and production of bone matrix, and in addition, are responsible for the growth spurt that often occurs during adolescence. They also promote the conversion of the epiphyseal plate to the epiphyseal line (i.e., cartilage to its bony remnant), thus bringing an end to the longitudinal growth of bones. Additionally, calcitriol, the active form of vitamin D, is produced by the kidneys and stimulates the absorption of calcium and phosphate from the digestive tract. Aging and the... Skeletal System Osteoporosis is a disease characterized by a decrease in bone mass that occurs when the rate of bone resorption exceeds the rate of bone formation, a common occurrence as the body ages. Notice how this is different from Paget’s disease. In Paget’s disease, new bone is formed in an attempt to keep up with the resorption by the overactive osteoclasts, but that new bone is produced haphazardly. In fact, when a physician is evaluating a patient with thinning bone, he or she will test for osteoporosis and Paget’s disease (as well as other diseases). Osteoporosis does not have the elevated blood levels of alkaline phosphatase found in Paget’s disease. While osteoporosis can involve any bone, it most commonly affects the proximal ends of the femur, vertebrae, and wrist. As a result of the loss of bone density, the osseous tissue may not provide adequate support for everyday functions, and something as simple as a sneeze can cause a vertebral fracture. When an elderly person falls and breaks a hip (really, the femur), it is very likely the femur that broke first, which resulted in the fall. Histologically, osteoporosis is characterized by a reduction in the thickness of compact bone and the number and size of trabeculae in cancellous bone. Figure 6.23 shows that women lose bone mass more quickly than men starting at about 50 years of age. This occurs because 50 is the approximate age at which women go through menopause. Not only do their menstrual periods lessen and eventually cease, but their ovaries reduce in size and then cease the production of estrogen, a hormone that promotes osteoblastic activity and production of bone matrix. Thus, osteoporosis is more common in women than in men, but men can develop it, too. Anyone with a family history of osteoporosis has a greater risk of developing the disease, so the best treatment is prevention, which should start with a childhood diet that includes adequate intake of calcium and vitamin D and a lifestyle that includes weight-bearing exercise. These actions, as discussed above, are important in building bone mass. Promoting proper nutrition and weight-bearing exercise early in life can maximize bone mass before the age of 30, thus reducing the risk of osteoporosis. For many elderly people, a hip fracture can be life threatening. The fracture itself may not be serious, but the immobility that comes during the healing process can lead to the formation of blood clots that can lodge in the capillaries of the lungs, resulting in respiratory failure; pneumonia due to the lack of poor air exchange that accompanies immobility; pressure sores (bed sores) that allow pathogens to enter the body and cause infections; and urinary tract infections from catheterization. Current treatments for managing osteoporosis include bisphosphonates (the same medications often used in Paget’s disease), calcitonin, and estrogen (for women only). Minimizing the risk of falls, for example, by removing tripping hazards, is also an important step in managing the potential outcomes from the disease. Hormones That Influence Osteoclasts Bone modeling and remodeling require osteoclasts to resorb unneeded, damaged, or old bone, and osteoblasts to lay down new bone. Two hormones that affect the osteoclasts are parathyroid hormone (PTH) and calcitonin. PTH stimulates osteoclast proliferation and activity. As a result, calcium is released from the bones into the circulation, thus increasing the calcium ion concentration in the blood. PTH also promotes the reabsorption of calcium by the kidney tubules, which can affect calcium homeostasis (see below). The small intestine is also affected by PTH, albeit indirectly. Because another function of PTH is to stimulate the synthesis of vitamin D, and because vitamin D promotes intestinal absorption of calcium, PTH indirectly increases calcium uptake by the small intestine. Calcitonin, a hormone secreted by the thyroid gland, has some effects that counteract those of PTH. Calcitonin inhibits osteoclast activity and stimulates calcium uptake by the bones, thus reducing the concentration of calcium ions in the blood. As evidenced by their opposing functions in maintaining calcium homeostasis, PTH and calcitonin are generally not secreted at the same time. Table 6.6 summarizes the hormones that influence the skeletal system. Hormones That Affect the Skeletal System Hormone Role Growth hormone Increases length of long bones, enhances mineralization, and improves bone density Thyroxine Stimulates bone growth and promotes synthesis of bone matrix Sex hormones Promote osteoblastic activity and production of bone matrix; responsible for adolescent growth spurt; promote conversion of epiphyseal plate to epiphyseal line Calcitriol Stimulates absorption of calcium and phosphate from digestive tract Parathyroid hormone Stimulates osteoclast proliferation and resorption of bone by osteoclasts; promotes reabsorption of calcium by kidney tubules; indirectly increases calcium absorption by small intestine Calcitonin Inhibits osteoclast activity and stimulates calcium uptake by bones Table 6.6 6.7 Calcium Homeostasis: Interactions of the Skeletal System and Other Organ Systems Learning Objectives By the end of this section, you will be able to: Describe the effect of too much or too little calcium on the body Explain the process of calcium homeostasis Calcium is not only the most abundant mineral in bone, it is also the most abundant mineral in the human body. Calcium ions are needed not only for bone mineralization but for tooth health, regulation of the heart rate and strength of contraction, blood coagulation, contraction of smooth and skeletal muscle cells, and regulation of nerve impulse conduction. The normal level of calcium in the blood is about 10 mg/dL. When the body cannot maintain this level, a person will experience hypo- or hypercalcemia. Hypocalcemia , a condition characterized by abnormally low levels of calcium, can have an adverse effect on a number of different body systems including circulation, muscles, nerves, and bone. Without adequate calcium, blood has difficulty coagulating, the heart may skip beats or stop beating altogether, muscles may have difficulty contracting, nerves may have difficulty functioning, and bones may become brittle. The causes of hypocalcemia can range from hormonal imbalances to an improper diet. Treatments vary according to the cause, but prognoses are generally good. Conversely, in hypercalcemia , a condition characterized by abnormally high levels of calcium, the nervous system is underactive, which results in lethargy, sluggish reflexes, constipation and loss of appetite, confusion, and in severe cases, coma. Obviously, calcium homeostasis is critical. The skeletal, endocrine, and digestive systems play a role in this, but the kidneys do, too. These body systems work together to maintain a normal calcium level in the blood ( Figure 6.24 ). Calcium is a chemical element that cannot be produced by any biological processes. The only way it can enter the body is through the diet. The bones act as a storage site for calcium: The body deposits calcium in the bones when blood levels get too high, and it releases calcium when blood levels drop too low. This process is regulated by PTH, vitamin D, and calcitonin. Cells of the parathyroid gland have plasma membrane receptors for calcium. When calcium is not binding to these receptors, the cells release PTH, which stimulates osteoclast proliferation and resorption of bone by osteoclasts. This demineralization process releases calcium into the blood. PTH promotes reabsorption of calcium from the urine by the kidneys, so that the calcium returns to the blood. Finally, PTH stimulates the synthesis of vitamin D, which in turn, stimulates calcium absorption from any digested food in the small intestine. When all these processes return blood calcium levels to normal, there is enough calcium to bind with the receptors on the surface of the cells of the parathyroid glands, and this cycle of events is turned off ( Figure 6.24 ). When blood levels of calcium get too high, the thyroid gland is stimulated to release calcitonin ( Figure 6.24 ), which inhibits osteoclast activity and stimulates calcium uptake by the bones, but also decreases reabsorption of calcium by the kidneys. All of these actions lower blood levels of calcium. When blood calcium levels return to normal, the thyroid gland stops secreting calcitonin.
biology
Chapter Outline 41.1 Osmoregulation and Osmotic Balance 41.2 The Kidneys and Osmoregulatory Organs 41.3 Excretion Systems 41.4 Nitrogenous Wastes 41.5 Hormonal Control of Osmoregulatory Functions Introduction The daily intake recommendation for human water consumption is eight to ten glasses of water. In order to achieve a healthy balance, the human body should excrete the eight to ten glasses of water every day. This occurs via the processes of urination, defecation, sweating and, to a small extent, respiration. The organs and tissues of the human body are soaked in fluids that are maintained at constant temperature, pH, and solute concentration, all crucial elements of homeostasis. The solutes in body fluids are mainly mineral salts and sugars, and osmotic regulation is the process by which the mineral salts and water are kept in balance. Osmotic homeostasis is maintained despite the influence of external factors like temperature, diet, and weather conditions.
[ { "answer": { "ans_choice": 0, "ans_text": "shrink due to water loss" }, "bloom": null, "hl_context": "Osmosis is the diffusion of water across a membrane in response to osmotic pressure caused by an imbalance of molecules on either side of the membrane . Osmoregulation is the process of maintenance of salt and water balance ( osmotic balance ) across membranes within the body ’ s fluids , which are composed of water , plus electrolytes and non-electrolytes . An electrolyte is a solute that dissociates into ions when dissolved in water . A non-electrolyte , in contrast , doesn ’ t dissociate into ions during water dissolution . Both electrolytes and non-electrolytes contribute to the osmotic balance . The body ’ s fluids include blood plasma , the cytosol within cells , and interstitial fluid , the fluid that exists in the spaces between cells and tissues of the body . The membranes of the body ( such as the pleural , serous , and cell membranes ) are semi-permeable membranes . Semi-permeable membranes are permeable ( or permissive ) to certain types of solutes and water . Solutions on two sides of a semi-permeable membrane tend to equalize in solute concentration by movement of solutes and / or water across the membrane . As seen in Figure 41.2 , a cell placed in water tends to swell due to gain of water from the hypotonic or “ low salt ” environment . <hl> A cell placed in a solution with higher salt concentration , on the other hand , tends to make the membrane shrivel up due to loss of water into the hypertonic or “ high salt ” environment . <hl> Isotonic cells have an equal concentration of solutes inside and outside the cell ; this equalizes the osmotic pressure on either side of the cell membrane which is a semi-permeable membrane .", "hl_sentences": "A cell placed in a solution with higher salt concentration , on the other hand , tends to make the membrane shrivel up due to loss of water into the hypertonic or “ high salt ” environment .", "question": { "cloze_format": "Cells in a hypertonic solution tend to ___ .", "normal_format": "What do cells in a hypertonic solution tend to?", "question_choices": [ "shrink due to water loss", "swell due to water gain", "stay the same size due to water moving into and out of the cell at the same rate", "none of the above" ], "question_id": "fs-idp206826416", "question_text": "Cells in a hypertonic solution tend to:" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 2, "ans_text": "cells present in the DCT and collecting tubules." }, "bloom": null, "hl_context": "Although parts of the renal tubules are named proximal and distal , in a cross-section of the kidney , the tubules are placed close together and in contact with each other and the glomerulus . This allows for exchange of chemical messengers between the different cell types . <hl> For example , the DCT ascending limb of the loop of Henle has masses of cells called macula densa , which are in contact with cells of the afferent arterioles called juxtaglomerular cells . <hl> Together , the macula densa and juxtaglomerular cells form the juxtaglomerular complex ( JGC ) . The JGC is an endocrine structure that secretes the enzyme renin and the hormone erythropoietin . When hormones trigger the macula densa cells in the DCT due to variations in blood volume , blood pressure , or electrolyte balance , these cells can immediately communicate the problem to the capillaries in the afferent and efferent arterioles , which can constrict or relax to change the glomerular filtration rate of the kidneys .", "hl_sentences": "For example , the DCT ascending limb of the loop of Henle has masses of cells called macula densa , which are in contact with cells of the afferent arterioles called juxtaglomerular cells .", "question": { "cloze_format": "The macula densa is/are ___ .", "normal_format": "What is/are the macula densa?", "question_choices": [ "present in the renal medulla.", "dense tissue present in the outer layer of the kidney.", "cells present in the DCT and collecting tubules.", "present in blood capillaries." ], "question_id": "fs-idp67034864", "question_text": "The macula densa is/are:" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 1, "ans_text": "300 mOsm" }, "bloom": null, "hl_context": "Thus , for ions that have a charge of one , one milliequivalent is equal to one millimole . For ions that have a charge of two ( like calcium ) , one milliequivalent is equal to 0.5 millimoles . Another unit for the expression of electrolyte concentration is the milliosmole ( mOsm ) , which is the number of milliequivalents of solute per kilogram of solvent . <hl> Body fluids are usually maintained within the range of 280 to 300 mOsm . <hl>", "hl_sentences": "Body fluids are usually maintained within the range of 280 to 300 mOsm .", "question": { "cloze_format": "The osmolarity of body fluids is maintained at ________.", "normal_format": "The osmolarity of body fluids is maintained at which of the following?", "question_choices": [ "100 mOsm", "300 mOsm", "1000 mOsm", "it is not constantly maintained" ], "question_id": "fs-idm5875280", "question_text": "The osmolarity of body fluids is maintained at ________." }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 0, "ans_text": "adrenal" }, "bloom": null, "hl_context": "The kidneys , illustrated in Figure 41.4 , are a pair of bean-shaped structures that are located just below and posterior to the liver in the peritoneal cavity . <hl> The adrenal glands sit on top of each kidney and are also called the suprarenal glands . <hl> Kidneys filter blood and purify it . All the blood in the human body is filtered many times a day by the kidneys ; these organs use up almost 25 percent of the oxygen absorbed through the lungs to perform this function . Oxygen allows the kidney cells to efficiently manufacture chemical energy in the form of ATP through aerobic respiration . The filtrate coming out of the kidneys is called urine .", "hl_sentences": "The adrenal glands sit on top of each kidney and are also called the suprarenal glands .", "question": { "cloze_format": "The gland located at the top of the kidney is the ________ gland.", "normal_format": "Which gland is located at the top of the kidney?", "question_choices": [ "adrenal", "pituitary", "thyroid", "thymus" ], "question_id": "fs-idm118933104", "question_text": "The gland located at the top of the kidney is the ________ gland." }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 2, "ans_text": "both a and b" }, "bloom": null, "hl_context": "Malpighian Tubules of Insects Malpighian tubules are found lining the gut of some species of arthropods , such as the bee illustrated in Figure 41.11 . They are usually found in pairs and the number of tubules varies with the species of insect . Malpighian tubules are convoluted , which increases their surface area , and they are lined with microvilli for reabsorption and maintenance of osmotic balance . Malpighian tubules work cooperatively with specialized glands in the wall of the rectum . <hl> Body fluids are not filtered as in the case of nephridia ; urine is produced by tubular secretion mechanisms by the cells lining the Malpighian tubules that are bathed in hemolymph ( a mixture of blood and interstitial fluid that is found in insects and other arthropods as well as most mollusks ) . <hl> Metabolic wastes like uric acid freely diffuse into the tubules . <hl> There are exchange pumps lining the tubules , which actively transport H + ions into the cell and K + or Na + ions out ; water passively follows to form urine . <hl> <hl> The secretion of ions alters the osmotic pressure which draws water , electrolytes , and nitrogenous waste ( uric acid ) into the tubules . <hl> Water and electrolytes are reabsorbed when these organisms are faced with low-water environments , and uric acid is excreted as a thick paste or powder . Not dissolving wastes in water helps these organisms to conserve water ; this is especially important for life in dry environments .", "hl_sentences": "Body fluids are not filtered as in the case of nephridia ; urine is produced by tubular secretion mechanisms by the cells lining the Malpighian tubules that are bathed in hemolymph ( a mixture of blood and interstitial fluid that is found in insects and other arthropods as well as most mollusks ) . There are exchange pumps lining the tubules , which actively transport H + ions into the cell and K + or Na + ions out ; water passively follows to form urine . The secretion of ions alters the osmotic pressure which draws water , electrolytes , and nitrogenous waste ( uric acid ) into the tubules .", "question": { "cloze_format": "Active transport of K+ in Malpighian tubules ensures that ___ .", "normal_format": "What does active transport of K+ in Malpighian tubules ensure?", "question_choices": [ "water follows K+ to make urine", "osmotic balance is maintained between waste matter and bodily fluids", "both a and b", "neither a nor b" ], "question_id": "fs-idp86638128", "question_text": "Active transport of K+ in Malpighian tubules ensures that:" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 3, "ans_text": "both b and c" }, "bloom": null, "hl_context": "The most fundamental feature of life is the presence of a cell . In other words , a cell is the simplest functional unit of a life . Bacteria are unicellular , prokaryotic organisms that have some of the least complex life processes in place ; however , prokaryotes such as bacteria do not contain membrane-bound vacuoles . <hl> The cells of microorganisms like bacteria , protozoa , and fungi are bound by cell membranes and use them to interact with the environment . <hl> Some cells , including some leucocytes in humans , are able to engulf food by endocytosis — the formation of vesicles by involution of the cell membrane within the cells . The same vesicles are able to interact and exchange metabolites with the intracellular environment . <hl> In some unicellular eukaryotic organisms such as the amoeba , shown in Figure 41.9 , cellular wastes and excess water are excreted by exocytosis , when the contractile vacuoles merge with the cell membrane and expel wastes into the environment . <hl> Contractile vacuoles ( CV ) should not be confused with vacuoles , which store food or water .", "hl_sentences": "The cells of microorganisms like bacteria , protozoa , and fungi are bound by cell membranes and use them to interact with the environment . In some unicellular eukaryotic organisms such as the amoeba , shown in Figure 41.9 , cellular wastes and excess water are excreted by exocytosis , when the contractile vacuoles merge with the cell membrane and expel wastes into the environment .", "question": { "cloze_format": "Contractile vacuoles in microorganisms ___ .", "normal_format": "What do contractile vacuoles in microorganisms do?", "question_choices": [ "exclusively perform an excretory function", "can perform many functions, one of which is excretion of metabolic wastes", "originate from the cell membrane", "both b and c" ], "question_id": "fs-idp20615632", "question_text": "Contractile vacuoles in microorganisms:" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 3, "ans_text": "flatworms" }, "bloom": null, "hl_context": "As multi-cellular systems evolved to have organ systems that divided the metabolic needs of the body , individual organs evolved to perform the excretory function . Planaria are flatworms that live in fresh water . Their excretory system consists of two tubules connected to a highly branched duct system . The cells in the tubules are called flame cells ( or protonephridia ) because they have a cluster of cilia that looks like a flickering flame when viewed under the microscope , as illustrated in Figure 41.10 a . The cilia propel waste matter down the tubules and out of the body through excretory pores that open on the body surface ; cilia also draw water from the interstitial fluid , allowing for filtration . Any valuable metabolites are recovered by reabsorption . <hl> Flame cells are found in flatworms , including parasitic tapeworms and free-living planaria . <hl> They also maintain the organism ’ s osmotic balance .", "hl_sentences": "Flame cells are found in flatworms , including parasitic tapeworms and free-living planaria .", "question": { "cloze_format": "Flame cells are primitive excretory organs found in ________.", "normal_format": "Where are flame cells, primitive excretory organs, found?", "question_choices": [ "arthropods", "annelids", "mammals", "flatworms" ], "question_id": "fs-idp81908736", "question_text": "Flame cells are primitive excretory organs found in ________." }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 0, "ans_text": "blood urea nitrogen" }, "bloom": null, "hl_context": "The urea cycle utilizes five intermediate steps , catalyzed by five different enzymes , to convert ammonia to urea , as shown in Figure 41.12 . The amino acid L-ornithine gets converted into different intermediates before being regenerated at the end of the urea cycle . Hence , the urea cycle is also referred to as the ornithine cycle . The enzyme ornithine transcarbamylase catalyzes a key step in the urea cycle and its deficiency can lead to accumulation of toxic levels of ammonia in the body . The first two reactions occur in the mitochondria and the last three reactions occur in the cytosol . <hl> Urea concentration in the blood , called blood urea nitrogen or BUN , is used as an indicator of kidney function . <hl>", "hl_sentences": "Urea concentration in the blood , called blood urea nitrogen or BUN , is used as an indicator of kidney function .", "question": { "cloze_format": "BUN is ________.", "normal_format": "What is BUN?", "question_choices": [ "blood urea nitrogen", "blood uric acid nitrogen", "an indicator of blood volume", "an indicator of blood pressure" ], "question_id": "fs-idp143558720", "question_text": "BUN is ________." }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 2, "ans_text": "urea" }, "bloom": null, "hl_context": "Of the four major macromolecules in biological systems , both proteins and nucleic acids contain nitrogen . During the catabolism , or breakdown , of nitrogen-containing macromolecules , carbon , hydrogen , and oxygen are extracted and stored in the form of carbohydrates and fats . Excess nitrogen is excreted from the body . Nitrogenous wastes tend to form toxic ammonia , which raises the pH of body fluids . The formation of ammonia itself requires energy in the form of ATP and large quantities of water to dilute it out of a biological system . Animals that live in aquatic environments tend to release ammonia into the water . Animals that excrete ammonia are said to be ammonotelic . <hl> Terrestrial organisms have evolved other mechanisms to excrete nitrogenous wastes . <hl> <hl> The animals must detoxify ammonia by converting it into a relatively nontoxic form such as urea or uric acid . <hl> <hl> Mammals , including humans , produce urea , whereas reptiles and many terrestrial invertebrates produce uric acid . <hl> Animals that secrete urea as the primary nitrogenous waste material are called ureotelic animals .", "hl_sentences": "Terrestrial organisms have evolved other mechanisms to excrete nitrogenous wastes . The animals must detoxify ammonia by converting it into a relatively nontoxic form such as urea or uric acid . Mammals , including humans , produce urea , whereas reptiles and many terrestrial invertebrates produce uric acid .", "question": { "cloze_format": "Human beings accumulate ________ before excreting nitrogenous waste.", "normal_format": "What do human beings accumulate before excreting nitrogenous waste?", "question_choices": [ "nitrogen", "ammonia", "urea", "uric acid" ], "question_id": "fs-idp57677728", "question_text": "Human beings accumulate ________ before excreting nitrogenous waste." }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 0, "ans_text": "granular cells of the juxtaglomerular apparatus" }, "bloom": null, "hl_context": "The renin-angiotensin-aldosterone system , illustrated in Figure 41.15 proceeds through several steps to produce angiotensin II , which acts to stabilize blood pressure and volume . <hl> Renin ( secreted by a part of the juxtaglomerular complex ) is produced by the granular cells of the afferent and efferent arterioles . <hl> Thus , the kidneys control blood pressure and volume directly . Renin acts on angiotensinogen , which is made in the liver and converts it to angiotensin I . Angiotensin converting enzyme ( ACE ) converts angiotensin I to angiotensin II . Angiotensin II raises blood pressure by constricting blood vessels . It also triggers the release of the mineralocorticoid aldosterone from the adrenal cortex , which in turn stimulates the renal tubules to reabsorb more sodium . Angiotensin II also triggers the release of anti-diuretic hormone ( ADH ) from the hypothalamus , leading to water retention in the kidneys . It acts directly on the nephrons and decreases glomerular filtration rate . Medically , blood pressure can be controlled by drugs that inhibit ACE ( called ACE inhibitors ) .", "hl_sentences": "Renin ( secreted by a part of the juxtaglomerular complex ) is produced by the granular cells of the afferent and efferent arterioles .", "question": { "cloze_format": "Renin is made by ________.", "normal_format": "What is Renin made by?", "question_choices": [ "granular cells of the juxtaglomerular apparatus", "the kidneys", "the nephrons", "All of the above." ], "question_id": "fs-idm77856336", "question_text": "Renin is made by ________." }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 2, "ans_text": "lose salts and water" }, "bloom": null, "hl_context": "Mineralocorticoids are hormones synthesized by the adrenal cortex that affect osmotic balance . Aldosterone is a mineralocorticoid that regulates sodium levels in the blood . Almost all of the sodium in the blood is reclaimed by the renal tubules under the influence of aldosterone . Because sodium is always reabsorbed by active transport and water follows sodium to maintain osmotic balance , aldosterone manages not only sodium levels but also the water levels in body fluids . In contrast , the aldosterone also stimulates potassium secretion concurrently with sodium reabsorption . In contrast , absence of aldosterone means that no sodium gets reabsorbed in the renal tubules and all of it gets excreted in the urine . In addition , the daily dietary potassium load is not secreted and the retention of K + can cause a dangerous increase in plasma K + concentration . <hl> Patients who have Addison's disease have a failing adrenal cortex and cannot produce aldosterone . <hl> <hl> They lose sodium in their urine constantly , and if the supply is not replenished , the consequences can be fatal . <hl>", "hl_sentences": "Patients who have Addison's disease have a failing adrenal cortex and cannot produce aldosterone . They lose sodium in their urine constantly , and if the supply is not replenished , the consequences can be fatal .", "question": { "cloze_format": "Patients with Addison's disease ________.", "normal_format": "Which of the following is correct about patients with Addison's disease?", "question_choices": [ "retain water", "retain salts", "lose salts and water", "have too much aldosterone" ], "question_id": "fs-idm2601472", "question_text": "Patients with Addison's disease ________." }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 0, "ans_text": "epinephrine" }, "bloom": null, "hl_context": "<hl> Epinephrine and norepinephrine are released by the adrenal medulla and nervous system respectively . <hl> <hl> They are the flight / fight hormones that are released when the body is under extreme stress . <hl> During stress , much of the body ’ s energy is used to combat imminent danger . Kidney function is halted temporarily by epinephrine and norepinephrine . These hormones function by acting directly on the smooth muscles of blood vessels to constrict them . Once the afferent arterioles are constricted , blood flow into the nephrons stops . These hormones go one step further and trigger the renin-angiotensin-aldosterone system .", "hl_sentences": "Epinephrine and norepinephrine are released by the adrenal medulla and nervous system respectively . They are the flight / fight hormones that are released when the body is under extreme stress .", "question": { "cloze_format": "The hormone that elicits the “fight or flight” response is ___.", "normal_format": "Which hormone elicits the “fight or flight” response?", "question_choices": [ "epinephrine", "mineralcorticoids", "anti-diuretic hormone", "thyroxine" ], "question_id": "fs-idp78582464", "question_text": "Which hormone elicits the “fight or flight” response?" }, "references_are_paraphrase": null } ]
41
41.1 Osmoregulation and Osmotic Balance Learning Objectives By the end of this section, you will be able to: Define osmosis and explain its role within molecules Explain why osmoregulation and osmotic balance are important body functions Describe active transport mechanisms Explain osmolarity and the way in which it is measured Describe osmoregulators or osmoconformers and how these tools allow animals to adapt to different environments Osmosis is the diffusion of water across a membrane in response to osmotic pressure caused by an imbalance of molecules on either side of the membrane. Osmoregulation is the process of maintenance of salt and water balance ( osmotic balance ) across membranes within the body’s fluids, which are composed of water, plus electrolytes and non-electrolytes. An electrolyte is a solute that dissociates into ions when dissolved in water. A non-electrolyte , in contrast, doesn’t dissociate into ions during water dissolution. Both electrolytes and non-electrolytes contribute to the osmotic balance. The body’s fluids include blood plasma, the cytosol within cells, and interstitial fluid, the fluid that exists in the spaces between cells and tissues of the body. The membranes of the body (such as the pleural, serous, and cell membranes) are semi-permeable membranes . Semi-permeable membranes are permeable (or permissive) to certain types of solutes and water. Solutions on two sides of a semi-permeable membrane tend to equalize in solute concentration by movement of solutes and/or water across the membrane. As seen in Figure 41.2 , a cell placed in water tends to swell due to gain of water from the hypotonic or “low salt” environment. A cell placed in a solution with higher salt concentration, on the other hand, tends to make the membrane shrivel up due to loss of water into the hypertonic or “high salt” environment. Isotonic cells have an equal concentration of solutes inside and outside the cell; this equalizes the osmotic pressure on either side of the cell membrane which is a semi-permeable membrane. The body does not exist in isolation. There is a constant input of water and electrolytes into the system. While osmoregulation is achieved across membranes within the body, excess electrolytes and wastes are transported to the kidneys and excreted, helping to maintain osmotic balance. Need for Osmoregulation Biological systems constantly interact and exchange water and nutrients with the environment by way of consumption of food and water and through excretion in the form of sweat, urine, and feces. Without a mechanism to regulate osmotic pressure, or when a disease damages this mechanism, there is a tendency to accumulate toxic waste and water, which can have dire consequences. Mammalian systems have evolved to regulate not only the overall osmotic pressure across membranes, but also specific concentrations of important electrolytes in the three major fluid compartments: blood plasma, extracellular fluid, and intracellular fluid. Since osmotic pressure is regulated by the movement of water across membranes, the volume of the fluid compartments can also change temporarily. Because blood plasma is one of the fluid components, osmotic pressures have a direct bearing on blood pressure. Transport of Electrolytes across Cell Membranes Electrolytes, such as sodium chloride, ionize in water, meaning that they dissociate into their component ions. In water, sodium chloride (NaCl), dissociates into the sodium ion (Na + ) and the chloride ion (Cl – ). The most important ions, whose concentrations are very closely regulated in body fluids, are the cations sodium (Na + ), potassium (K + ), calcium (Ca +2 ), magnesium (Mg +2 ), and the anions chloride (Cl - ), carbonate (CO 3 -2 ), bicarbonate (HCO 3 - ), and phosphate(PO 3 - ). Electrolytes are lost from the body during urination and perspiration. For this reason, athletes are encouraged to replace electrolytes and fluids during periods of increased activity and perspiration. Osmotic pressure is influenced by the concentration of solutes in a solution. It is directly proportional to the number of solute atoms or molecules and not dependent on the size of the solute molecules. Because electrolytes dissociate into their component ions, they, in essence, add more solute particles into the solution and have a greater effect on osmotic pressure, per mass than compounds that do not dissociate in water, such as glucose. Water can pass through membranes by passive diffusion. If electrolyte ions could passively diffuse across membranes, it would be impossible to maintain specific concentrations of ions in each fluid compartment therefore they require special mechanisms to cross the semi-permeable membranes in the body. This movement can be accomplished by facilitated diffusion and active transport. Facilitated diffusion requires protein-based channels for moving the solute. Active transport requires energy in the form of ATP conversion, carrier proteins, or pumps in order to move ions against the concentration gradient. Concept of Osmolality and Milliequivalent In order to calculate osmotic pressure, it is necessary to understand how solute concentrations are measured. The unit for measuring solutes is the mole . One mole is defined as the gram molecular weight of the solute. For example, the molecular weight of sodium chloride is 58.44. Thus, one mole of sodium chloride weighs 58.44 grams. The molarity of a solution is the number of moles of solute per liter of solution. The molality of a solution is the number of moles of solute per kilogram of solvent. If the solvent is water, one kilogram of water is equal to one liter of water. While molarity and molality are used to express the concentration of solutions, electrolyte concentrations are usually expressed in terms of milliequivalents per liter (mEq/L): the mEq/L is equal to the ion concentration (in millimoles) multiplied by the number of electrical charges on the ion. The unit of milliequivalent takes into consideration the ions present in the solution (since electrolytes form ions in aqueous solutions) and the charge on the ions. Thus, for ions that have a charge of one, one milliequivalent is equal to one millimole. For ions that have a charge of two (like calcium), one milliequivalent is equal to 0.5 millimoles. Another unit for the expression of electrolyte concentration is the milliosmole (mOsm), which is the number of milliequivalents of solute per kilogram of solvent. Body fluids are usually maintained within the range of 280 to 300 mOsm. Osmoregulators and Osmoconformers Persons lost at sea without any fresh water to drink are at risk of severe dehydration because the human body cannot adapt to drinking seawater, which is hypertonic in comparison to body fluids. Organisms such as goldfish that can tolerate only a relatively narrow range of salinity are referred to as stenohaline. About 90 percent of all bony fish are restricted to either freshwater or seawater. They are incapable of osmotic regulation in the opposite environment. It is possible, however, for a few fishes like salmon to spend part of their life in fresh water and part in sea water. Organisms like the salmon and molly that can tolerate a relatively wide range of salinity are referred to as euryhaline organisms. This is possible because some fish have evolved osmoregulatory mechanisms to survive in all kinds of aquatic environments. When they live in fresh water, their bodies tend to take up water because the environment is relatively hypotonic, as illustrated in Figure 41.3 a . In such hypotonic environments, these fish do not drink much water. Instead, they pass a lot of very dilute urine, and they achieve electrolyte balance by active transport of salts through the gills. When they move to a hypertonic marine environment, these fish start drinking sea water; they excrete the excess salts through their gills and their urine, as illustrated in Figure 41.3 b . Most marine invertebrates, on the other hand, may be isotonic with sea water ( osmoconformers ). Their body fluid concentrations conform to changes in seawater concentration. Cartilaginous fishes’ salt composition of the blood is similar to bony fishes; however, the blood of sharks contains the organic compounds urea and trimethylamine oxide (TMAO). This does not mean that their electrolyte composition is similar to that of sea water. They achieve isotonicity with the sea by storing large concentrations of urea. These animals that secrete urea are called ureotelic animals. TMAO stabilizes proteins in the presence of high urea levels, preventing the disruption of peptide bonds that would occur in other animals exposed to similar levels of urea. Sharks are cartilaginous fish with a rectal gland to secrete salt and assist in osmoregulation. Career Connection Dialysis Technician Dialysis is a medical process of removing wastes and excess water from the blood by diffusion and ultrafiltration. When kidney function fails, dialysis must be done to artificially rid the body of wastes. This is a vital process to keep patients alive. In some cases, the patients undergo artificial dialysis until they are eligible for a kidney transplant. In others who are not candidates for kidney transplants, dialysis is a life-long necessity. Dialysis technicians typically work in hospitals and clinics. While some roles in this field include equipment development and maintenance, most dialysis technicians work in direct patient care. Their on-the-job duties, which typically occur under the direct supervision of a registered nurse, focus on providing dialysis treatments. This can include reviewing patient history and current condition, assessing and responding to patient needs before and during treatment, and monitoring the dialysis process. Treatment may include taking and reporting a patient’s vital signs and preparing solutions and equipment to ensure accurate and sterile procedures. 41.2 The Kidneys and Osmoregulatory Organs Learning Objectives By the end of this section, you will be able to: Explain how the kidneys serve as the main osmoregulatory organs in mammalian systems Describe the structure of the kidneys and the functions of the parts of the kidney Describe how the nephron is the functional unit of the kidney and explain how it actively filters blood and generates urine Detail the three steps in the formation of urine: glomerular filtration, tubular reabsorption, and tubular secretion Although the kidneys are the major osmoregulatory organ, the skin and lungs also play a role in the process. Water and electrolytes are lost through sweat glands in the skin, which helps moisturize and cool the skin surface, while the lungs expel a small amount of water in the form of mucous secretions and via evaporation of water vapor. Kidneys: The Main Osmoregulatory Organ The kidneys , illustrated in Figure 41.4 , are a pair of bean-shaped structures that are located just below and posterior to the liver in the peritoneal cavity. The adrenal glands sit on top of each kidney and are also called the suprarenal glands. Kidneys filter blood and purify it. All the blood in the human body is filtered many times a day by the kidneys; these organs use up almost 25 percent of the oxygen absorbed through the lungs to perform this function. Oxygen allows the kidney cells to efficiently manufacture chemical energy in the form of ATP through aerobic respiration. The filtrate coming out of the kidneys is called urine . Kidney Structure Externally, the kidneys are surrounded by three layers, illustrated in Figure 41.5 . The outermost layer is a tough connective tissue layer called the renal fascia . The second layer is called the perirenal fat capsule , which helps anchor the kidneys in place. The third and innermost layer is the renal capsule . Internally, the kidney has three regions—an outer cortex , a medulla in the middle, and the renal pelvis in the region called the hilum of the kidney. The hilum is the concave part of the bean-shape where blood vessels and nerves enter and exit the kidney; it is also the point of exit for the ureters. The renal cortex is granular due to the presence of nephrons —the functional unit of the kidney. The medulla consists of multiple pyramidal tissue masses, called the renal pyramids . In between the pyramids are spaces called renal columns through which the blood vessels pass. The tips of the pyramids, called renal papillae, point toward the renal pelvis. There are, on average, eight renal pyramids in each kidney. The renal pyramids along with the adjoining cortical region are called the lobes of the kidney . The renal pelvis leads to the ureter on the outside of the kidney. On the inside of the kidney, the renal pelvis branches out into two or three extensions called the major calyces , which further branch into the minor calyces. The ureters are urine-bearing tubes that exit the kidney and empty into the urinary bladder . Visual Connection Which of the following statements about the kidney is false? The renal pelvis drains into the ureter. The renal pyramids are in the medulla. The cortex covers the capsule. Nephrons are in the renal cortex. Because the kidney filters blood, its network of blood vessels is an important component of its structure and function. The arteries, veins, and nerves that supply the kidney enter and exit at the renal hilum. Renal blood supply starts with the branching of the aorta into the renal arteries (which are each named based on the region of the kidney they pass through) and ends with the exiting of the renal veins to join the inferior vena cava . The renal arteries split into several segmental arteries upon entering the kidneys. Each segmental artery splits further into several interlobar arteries and enters the renal columns, which supply the renal lobes. The interlobar arteries split at the junction of the renal cortex and medulla to form the arcuate arteries . The arcuate “bow shaped” arteries form arcs along the base of the medullary pyramids. Cortical radiate arteries , as the name suggests, radiate out from the arcuate arteries. The cortical radiate arteries branch into numerous afferent arterioles, and then enter the capillaries supplying the nephrons. Veins trace the path of the arteries and have similar names, except there are no segmental veins. As mentioned previously, the functional unit of the kidney is the nephron, illustrated in Figure 41.6 . Each kidney is made up of over one million nephrons that dot the renal cortex, giving it a granular appearance when sectioned sagittally. There are two types of nephrons— cortical nephrons (85 percent), which are deep in the renal cortex, and juxtamedullary nephrons (15 percent), which lie in the renal cortex close to the renal medulla. A nephron consists of three parts—a renal corpuscle , a renal tubule , and the associated capillary network, which originates from the cortical radiate arteries. Visual Connection Which of the following statements about the nephron is false? The collecting duct empties into the distal convoluted tubule. The Bowman’s capsule surrounds the glomerulus. The loop of Henle is between the proximal and distal convoluted tubules. The loop of Henle empties into the distal convoluted tubule. Renal Corpuscle The renal corpuscle, located in the renal cortex, is made up of a network of capillaries known as the glomerulus and the capsule, a cup-shaped chamber that surrounds it, called the glomerular or Bowman's capsule . Renal Tubule The renal tubule is a long and convoluted structure that emerges from the glomerulus and can be divided into three parts based on function. The first part is called the proximal convoluted tubule (PCT) due to its proximity to the glomerulus; it stays in the renal cortex. The second part is called the loop of Henle , or nephritic loop, because it forms a loop (with descending and ascending limbs ) that goes through the renal medulla. The third part of the renal tubule is called the distal convoluted tubule (DCT) and this part is also restricted to the renal cortex. The DCT, which is the last part of the nephron, connects and empties its contents into collecting ducts that line the medullary pyramids. The collecting ducts amass contents from multiple nephrons and fuse together as they enter the papillae of the renal medulla. Capillary Network within the Nephron The capillary network that originates from the renal arteries supplies the nephron with blood that needs to be filtered. The branch that enters the glomerulus is called the afferent arteriole . The branch that exits the glomerulus is called the efferent arteriole . Within the glomerulus, the network of capillaries is called the glomerular capillary bed. Once the efferent arteriole exits the glomerulus, it forms the peritubular capillary network , which surrounds and interacts with parts of the renal tubule. In cortical nephrons, the peritubular capillary network surrounds the PCT and DCT. In juxtamedullary nephrons, the peritubular capillary network forms a network around the loop of Henle and is called the vasa recta . Link to Learning Go to this website to see another coronal section of the kidney and to explore an animation of the workings of nephrons. Kidney Function and Physiology Kidneys filter blood in a three-step process. First, the nephrons filter blood that runs through the capillary network in the glomerulus. Almost all solutes, except for proteins, are filtered out into the glomerulus by a process called glomerular filtration . Second, the filtrate is collected in the renal tubules. Most of the solutes get reabsorbed in the PCT by a process called tubular reabsorption . In the loop of Henle, the filtrate continues to exchange solutes and water with the renal medulla and the peritubular capillary network. Water is also reabsorbed during this step. Then, additional solutes and wastes are secreted into the kidney tubules during tubular secretion , which is, in essence, the opposite process to tubular reabsorption. The collecting ducts collect filtrate coming from the nephrons and fuse in the medullary papillae. From here, the papillae deliver the filtrate, now called urine, into the minor calyces that eventually connect to the ureters through the renal pelvis. This entire process is illustrated in Figure 41.7 . Glomerular Filtration Glomerular filtration filters out most of the solutes due to high blood pressure and specialized membranes in the afferent arteriole. The blood pressure in the glomerulus is maintained independent of factors that affect systemic blood pressure. The “leaky” connections between the endothelial cells of the glomerular capillary network allow solutes to pass through easily. All solutes in the glomerular capillaries, except for macromolecules like proteins, pass through by passive diffusion. There is no energy requirement at this stage of the filtration process. Glomerular filtration rate (GFR) is the volume of glomerular filtrate formed per minute by the kidneys. GFR is regulated by multiple mechanisms and is an important indicator of kidney function. Link to Learning To learn more about the vascular system of kidneys, click through this review and the steps of blood flow. Tubular Reabsorption and Secretion Tubular reabsorption occurs in the PCT part of the renal tubule. Almost all nutrients are reabsorbed, and this occurs either by passive or active transport. Reabsorption of water and some key electrolytes are regulated and can be influenced by hormones. Sodium (Na + ) is the most abundant ion and most of it is reabsorbed by active transport and then transported to the peritubular capillaries. Because Na + is actively transported out of the tubule, water follows it to even out the osmotic pressure. Water is also independently reabsorbed into the peritubular capillaries due to the presence of aquaporins, or water channels, in the PCT. This occurs due to the low blood pressure and high osmotic pressure in the peritubular capillaries. However, every solute has a transport maximum and the excess is not reabsorbed. In the loop of Henle, the permeability of the membrane changes. The descending limb is permeable to water, not solutes; the opposite is true for the ascending limb. Additionally, the loop of Henle invades the renal medulla, which is naturally high in salt concentration and tends to absorb water from the renal tubule and concentrate the filtrate. The osmotic gradient increases as it moves deeper into the medulla. Because two sides of the loop of Henle perform opposing functions, as illustrated in Figure 41.8 , it acts as a countercurrent multiplier . The vasa recta around it acts as the countercurrent exchanger . Visual Connection Loop diuretics are drugs sometimes used to treat hypertension. These drugs inhibit the reabsorption of Na + and Cl - ions by the ascending limb of the loop of Henle. A side effect is that they increase urination. Why do you think this is the case? By the time the filtrate reaches the DCT, most of the urine and solutes have been reabsorbed. If the body requires additional water, all of it can be reabsorbed at this point. Further reabsorption is controlled by hormones, which will be discussed in a later section. Excretion of wastes occurs due to lack of reabsorption combined with tubular secretion. Undesirable products like metabolic wastes, urea, uric acid, and certain drugs, are excreted by tubular secretion. Most of the tubular secretion happens in the DCT, but some occurs in the early part of the collecting duct. Kidneys also maintain an acid-base balance by secreting excess H + ions. Although parts of the renal tubules are named proximal and distal, in a cross-section of the kidney, the tubules are placed close together and in contact with each other and the glomerulus. This allows for exchange of chemical messengers between the different cell types. For example, the DCT ascending limb of the loop of Henle has masses of cells called macula densa , which are in contact with cells of the afferent arterioles called juxtaglomerular cells . Together, the macula densa and juxtaglomerular cells form the juxtaglomerular complex (JGC). The JGC is an endocrine structure that secretes the enzyme renin and the hormone erythropoietin. When hormones trigger the macula densa cells in the DCT due to variations in blood volume, blood pressure, or electrolyte balance, these cells can immediately communicate the problem to the capillaries in the afferent and efferent arterioles, which can constrict or relax to change the glomerular filtration rate of the kidneys. Career Connection Nephrologist A nephrologist studies and deals with diseases of the kidneys—both those that cause kidney failure (such as diabetes) and the conditions that are produced by kidney disease (such as hypertension). Blood pressure, blood volume, and changes in electrolyte balance come under the purview of a nephrologist. Nephrologists usually work with other physicians who refer patients to them or consult with them about specific diagnoses and treatment plans. Patients are usually referred to a nephrologist for symptoms such as blood or protein in the urine, very high blood pressure, kidney stones, or renal failure. Nephrology is a subspecialty of internal medicine. To become a nephrologist, medical school is followed by additional training to become certified in internal medicine. An additional two or more years is spent specifically studying kidney disorders and their accompanying effects on the body. 41.3 Excretion Systems Learning Objectives By the end of this section, you will be able to: Explain how vacuoles, present in microorganisms, work to excrete waste Describe the way in which flame cells and nephridia in worms perform excretory functions and maintain osmotic balance Explain how insects use Malpighian tubules to excrete wastes and maintain osmotic balance Microorganisms and invertebrate animals use more primitive and simple mechanisms to get rid of their metabolic wastes than the mammalian system of kidney and urinary function. Three excretory systems evolved in organisms before complex kidneys: vacuoles, flame cells, and Malpighian tubules. Contractile Vacuoles in Microorganisms The most fundamental feature of life is the presence of a cell. In other words, a cell is the simplest functional unit of a life. Bacteria are unicellular, prokaryotic organisms that have some of the least complex life processes in place; however, prokaryotes such as bacteria do not contain membrane-bound vacuoles. The cells of microorganisms like bacteria, protozoa, and fungi are bound by cell membranes and use them to interact with the environment. Some cells, including some leucocytes in humans, are able to engulf food by endocytosis—the formation of vesicles by involution of the cell membrane within the cells. The same vesicles are able to interact and exchange metabolites with the intracellular environment. In some unicellular eukaryotic organisms such as the amoeba, shown in Figure 41.9 , cellular wastes and excess water are excreted by exocytosis, when the contractile vacuoles merge with the cell membrane and expel wastes into the environment. Contractile vacuoles (CV) should not be confused with vacuoles, which store food or water. Flame Cells of Planaria and Nephridia of Worms As multi-cellular systems evolved to have organ systems that divided the metabolic needs of the body, individual organs evolved to perform the excretory function. Planaria are flatworms that live in fresh water. Their excretory system consists of two tubules connected to a highly branched duct system. The cells in the tubules are called flame cells (or protonephridia ) because they have a cluster of cilia that looks like a flickering flame when viewed under the microscope, as illustrated in Figure 41.10 a . The cilia propel waste matter down the tubules and out of the body through excretory pores that open on the body surface; cilia also draw water from the interstitial fluid, allowing for filtration. Any valuable metabolites are recovered by reabsorption. Flame cells are found in flatworms, including parasitic tapeworms and free-living planaria. They also maintain the organism’s osmotic balance. Earthworms (annelids) have slightly more evolved excretory structures called nephridia , illustrated in Figure 41.10 b . A pair of nephridia is present on each segment of the earthworm. They are similar to flame cells in that they have a tubule with cilia. Excretion occurs through a pore called the nephridiopore . They are more evolved than the flame cells in that they have a system for tubular reabsorption by a capillary network before excretion. Malpighian Tubules of Insects Malpighian tubules are found lining the gut of some species of arthropods, such as the bee illustrated in Figure 41.11 . They are usually found in pairs and the number of tubules varies with the species of insect. Malpighian tubules are convoluted, which increases their surface area, and they are lined with microvilli for reabsorption and maintenance of osmotic balance. Malpighian tubules work cooperatively with specialized glands in the wall of the rectum. Body fluids are not filtered as in the case of nephridia; urine is produced by tubular secretion mechanisms by the cells lining the Malpighian tubules that are bathed in hemolymph (a mixture of blood and interstitial fluid that is found in insects and other arthropods as well as most mollusks). Metabolic wastes like uric acid freely diffuse into the tubules. There are exchange pumps lining the tubules, which actively transport H + ions into the cell and K + or Na + ions out; water passively follows to form urine. The secretion of ions alters the osmotic pressure which draws water, electrolytes, and nitrogenous waste (uric acid) into the tubules. Water and electrolytes are reabsorbed when these organisms are faced with low-water environments, and uric acid is excreted as a thick paste or powder. Not dissolving wastes in water helps these organisms to conserve water; this is especially important for life in dry environments. Link to Learning See a dissected cockroach, including a close-up look at its Malpighian tubules, in this video . 41.4 Nitrogenous Wastes Learning Objectives By the end of this section, you will be able to: Compare and contrast the way in which aquatic animals and terrestrial animals can eliminate toxic ammonia from their systems Compare the major byproduct of ammonia metabolism in vertebrate animals to that of birds, insects, and reptiles Of the four major macromolecules in biological systems, both proteins and nucleic acids contain nitrogen. During the catabolism, or breakdown, of nitrogen-containing macromolecules, carbon, hydrogen, and oxygen are extracted and stored in the form of carbohydrates and fats. Excess nitrogen is excreted from the body. Nitrogenous wastes tend to form toxic ammonia , which raises the pH of body fluids. The formation of ammonia itself requires energy in the form of ATP and large quantities of water to dilute it out of a biological system. Animals that live in aquatic environments tend to release ammonia into the water. Animals that excrete ammonia are said to be ammonotelic . Terrestrial organisms have evolved other mechanisms to excrete nitrogenous wastes. The animals must detoxify ammonia by converting it into a relatively nontoxic form such as urea or uric acid. Mammals, including humans, produce urea, whereas reptiles and many terrestrial invertebrates produce uric acid. Animals that secrete urea as the primary nitrogenous waste material are called ureotelic animals. Nitrogenous Waste in Terrestrial Animals: The Urea Cycle The urea cycle is the primary mechanism by which mammals convert ammonia to urea. Urea is made in the liver and excreted in urine. The overall chemical reaction by which ammonia is converted to urea is 2 NH 3 (ammonia) + CO 2 + 3 ATP + H 2 O → H 2 N-CO-NH 2 (urea) + 2 ADP + 4 P i + AMP. The urea cycle utilizes five intermediate steps, catalyzed by five different enzymes, to convert ammonia to urea, as shown in Figure 41.12 . The amino acid L-ornithine gets converted into different intermediates before being regenerated at the end of the urea cycle. Hence, the urea cycle is also referred to as the ornithine cycle. The enzyme ornithine transcarbamylase catalyzes a key step in the urea cycle and its deficiency can lead to accumulation of toxic levels of ammonia in the body. The first two reactions occur in the mitochondria and the last three reactions occur in the cytosol. Urea concentration in the blood, called blood urea nitrogen or BUN, is used as an indicator of kidney function. Evolution Connection Excretion of Nitrogenous Waste The theory of evolution proposes that life started in an aquatic environment. It is not surprising to see that biochemical pathways like the urea cycle evolved to adapt to a changing environment when terrestrial life forms evolved. Arid conditions probably led to the evolution of the uric acid pathway as a means of conserving water. Nitrogenous Waste in Birds and Reptiles: Uric Acid Birds, reptiles, and most terrestrial arthropods convert toxic ammonia to uric acid or the closely related compound guanine (guano) instead of urea. Mammals also form some uric acid during breakdown of nucleic acids. Uric acid is a compound similar to purines found in nucleic acids. It is water insoluble and tends to form a white paste or powder; it is excreted by birds, insects, and reptiles. Conversion of ammonia to uric acid requires more energy and is much more complex than conversion of ammonia to urea Figure 41.13 . Everyday Connection Gout Mammals use uric acid crystals as an antioxidant in their cells. However, too much uric acid tends to form kidney stones and may also cause a painful condition called gout, where uric acid crystals accumulate in the joints, as illustrated in Figure 41.14 . Food choices that reduce the amount of nitrogenous bases in the diet help reduce the risk of gout. For example, tea, coffee, and chocolate have purine-like compounds, called xanthines, and should be avoided by people with gout and kidney stones. 41.5 Hormonal Control of Osmoregulatory Functions Learning Objectives By the end of this section, you will be able to: Explain how hormonal cues help the kidneys synchronize the osmotic needs of the body Describe how hormones like epinephrine, norepinephrine, renin-angiotensin, aldosterone, anti-diuretic hormone, and atrial natriuretic peptide help regulate waste elimination, maintain correct osmolarity, and perform other osmoregulatory functions While the kidneys operate to maintain osmotic balance and blood pressure in the body, they also act in concert with hormones. Hormones are small molecules that act as messengers within the body. Hormones are typically secreted from one cell and travel in the bloodstream to affect a target cell in another portion of the body. Different regions of the nephron bear specialized cells that have receptors to respond to chemical messengers and hormones. Table 41.1 summarizes the hormones that control the osmoregulatory functions. Hormones That Affect Osmoregulation Hormone Where produced Function Epinephrine and Norepinephrine Adrenal medulla Can decrease kidney function temporarily by vasoconstriction Renin Kidney nephrons Increases blood pressure by acting on angiotensinogen Angiotensin Liver Angiotensin II affects multiple processes and increases blood pressure Aldosterone Adrenal cortex Prevents loss of sodium and water Anti-diuretic hormone (vasopressin) Hypothalamus (stored in the posterior pituitary) Prevents water loss Atrial natriuretic peptide Heart atrium Decreases blood pressure by acting as a vasodilator and increasing glomerular filtration rate; decreases sodium reabsorption in kidneys Table 41.1 Epinephrine and Norepinephrine Epinephrine and norepinephrine are released by the adrenal medulla and nervous system respectively. They are the flight/fight hormones that are released when the body is under extreme stress. During stress, much of the body’s energy is used to combat imminent danger. Kidney function is halted temporarily by epinephrine and norepinephrine. These hormones function by acting directly on the smooth muscles of blood vessels to constrict them. Once the afferent arterioles are constricted, blood flow into the nephrons stops. These hormones go one step further and trigger the renin-angiotensin-aldosterone system. Renin-Angiotensin-Aldosterone The renin-angiotensin-aldosterone system, illustrated in Figure 41.15 proceeds through several steps to produce angiotensin II , which acts to stabilize blood pressure and volume. Renin (secreted by a part of the juxtaglomerular complex) is produced by the granular cells of the afferent and efferent arterioles. Thus, the kidneys control blood pressure and volume directly. Renin acts on angiotensinogen, which is made in the liver and converts it to angiotensin I . Angiotensin converting enzyme (ACE) converts angiotensin I to angiotensin II. Angiotensin II raises blood pressure by constricting blood vessels. It also triggers the release of the mineralocorticoid aldosterone from the adrenal cortex, which in turn stimulates the renal tubules to reabsorb more sodium. Angiotensin II also triggers the release of anti-diuretic hormone (ADH) from the hypothalamus, leading to water retention in the kidneys. It acts directly on the nephrons and decreases glomerular filtration rate. Medically, blood pressure can be controlled by drugs that inhibit ACE (called ACE inhibitors). Mineralocorticoids Mineralocorticoids are hormones synthesized by the adrenal cortex that affect osmotic balance. Aldosterone is a mineralocorticoid that regulates sodium levels in the blood. Almost all of the sodium in the blood is reclaimed by the renal tubules under the influence of aldosterone. Because sodium is always reabsorbed by active transport and water follows sodium to maintain osmotic balance, aldosterone manages not only sodium levels but also the water levels in body fluids. In contrast, the aldosterone also stimulates potassium secretion concurrently with sodium reabsorption. In contrast, absence of aldosterone means that no sodium gets reabsorbed in the renal tubules and all of it gets excreted in the urine. In addition, the daily dietary potassium load is not secreted and the retention of K + can cause a dangerous increase in plasma K + concentration. Patients who have Addison's disease have a failing adrenal cortex and cannot produce aldosterone. They lose sodium in their urine constantly, and if the supply is not replenished, the consequences can be fatal. Antidiurectic Hormone As previously discussed, antidiuretic hormone or ADH (also called vasopressin ), as the name suggests, helps the body conserve water when body fluid volume, especially that of blood, is low. It is formed by the hypothalamus and is stored and released from the posterior pituitary. It acts by inserting aquaporins in the collecting ducts and promotes reabsorption of water. ADH also acts as a vasoconstrictor and increases blood pressure during hemorrhaging. Atrial Natriuretic Peptide Hormone The atrial natriuretic peptide (ANP) lowers blood pressure by acting as a vasodilator . It is released by cells in the atrium of the heart in response to high blood pressure and in patients with sleep apnea. ANP affects salt release, and because water passively follows salt to maintain osmotic balance, it also has a diuretic effect. ANP also prevents sodium reabsorption by the renal tubules, decreasing water reabsorption (thus acting as a diuretic) and lowering blood pressure. Its actions suppress the actions of aldosterone, ADH, and renin.
introduction_to_sociology
Learning Objectives 8.1 Technology Today Define technology and describe its evolution Understand technological inequality and issues related to unequal access to technology Describe the role of planned obsolescence in technological development 8.2 Media and Technology in Society Describe the evolution and current role of different media, like newspapers, television, and new media Understand the function of product advertising in media Demonstrate awareness of the social homogenization and social fragmentation that are occurring via modern society’s use of technology and media 8.3 Global Implications Explain the advantages and concerns of media globalization Understand the globalization of technology 8.4 Theoretical Perspectives on Media and Technology Understand and discuss how media and technology are analyzed through various sociological perspectives Introduction to Media and Technology How many good friends do you have? How many people do you meet up with for coffee or a movie? How many would you call with news about an illness or invite to your wedding? Now, how many “friends” do you have on Facebook? Technology has changed how we interact with each other. It has turned “friend” into a verb and has made it possible to share mundane news (“My dog just threw up under the bed! Ugh!”) with hundreds or even thousands of people who might know you only slightly, if at all. Through the magic of Facebook, you might know about an old elementary school friend’s new job before her mother does. At the same time that technology is expanding the boundaries of our social circles, various media are also changing how we perceive and interact with each other. We don’t only use Facebook to keep in touch with friends; we also use it to “like” certain TV shows, products, or celebrities. Even television is no longer a one-way medium but an interactive one. We are encouraged to tweet, text, or call in to vote for contestants in everything from singing competitions to matchmaking endeavors—bridging the gap between our entertainment and our own lives. How does technology change our lives for the better? Or does it? When you tweet a social cause or cut and paste a status update about cancer awareness on Facebook, are you promoting social change? Does the immediate and constant flow of information mean we are more aware and engaged than any society before us? Or are American Idol and Jersey Shore today’s version of ancient Rome’s “bread and circuses”––distractions and entertainment to keep the lower classes complacent to the inequities of our society? These are some of the questions that interest sociologists. How might we examine these issues from a sociological perspective? A functionalist would probably focus on what social purposes technology and media serve. For example, the web is both a form of technology and of media, and it links individuals and nations in a communication network that facilitates both small family discussions and global trade networks. A functionalist would also be interested in the manifest functions of media and technology, as well as their role in social dysfunction. Someone applying the conflict perspective would probably focus on the systematic inequality created by differential access to media and technology. For example, how can middle-class Americans be sure the news they hear is an objective account of reality, unsullied by monied political interests? Someone applying the interactionist perspective to technology and the media might seek to understand the difference between the real lives we lead and the reality depicted on “reality” television shows, such as Jersey Shore . Throughout this chapter, we will use our sociological imagination to explore how media and technology impact society.
[ { "answer": { "ans_choice": 1, "ans_text": "knowledge gap " }, "bloom": "1", "hl_context": "There are two forms of technological stratification . The first is differential class-based access to technology in the form of the digital divide . <hl> This digital divide has led to the second form , a knowledge gap , which is , as it sounds , an ongoing and increasing gap in information for those who have less access to technology . <hl> <hl> Simply put , students in well-funded schools receive more exposure to technology than students in poorly funded schools . <hl> Those students with more exposure gain more proficiency , making them far more marketable in an increasingly technology-based job market , leaving our society divided into those with technological knowledge and those without . Even as we improve access , we have failed to address an increasingly evident gap in e-readiness , the ability to sort through , interpret , and process knowledge ( Sciadas 2003 ) .", "hl_sentences": "This digital divide has led to the second form , a knowledge gap , which is , as it sounds , an ongoing and increasing gap in information for those who have less access to technology . Simply put , students in well-funded schools receive more exposure to technology than students in poorly funded schools .", "question": { "cloze_format": "The ________ can be directly attributed to the digital divide, because differential ability to access the internet leads directly to a differential ability to use the knowledge found on the internet.", "normal_format": "What can be directly attributed to the digital divide, because differential ability to access the internet leads directly to a differential ability to use the knowledge found on the internet?", "question_choices": [ "digital divide", "knowledge gap ", "feminist perspective", "e-gap" ], "question_id": "fs-id1202754", "question_text": "The ________ can be directly attributed to the digital divide, because differential ability to access the internet leads directly to a differential ability to use the knowledge found on the internet." }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 3, "ans_text": "planned obsolescence" }, "bloom": "3", "hl_context": "To some extent , this is a natural extension of new and emerging technologies . After all , who is going to cling to an enormous and slow desktop computer from 2000 when a few hundred dollars can buy one that is significantly faster and better ? But the practice is not always so benign . <hl> The classic example of planned obsolescence is the nylon stocking . <hl> <hl> Women ’ s stockings — once an everyday staple of women ’ s lives – – get “ runs ” or “ ladders ” after a few wearings . <hl> This requires the stockings to be discarded and new ones purchased . Not surprisingly , the garment industry did not invest heavily in finding a rip-proof fabric ; it was in their best interest that their product be regularly replaced . Sociology in the Real World Planned Obsolescence : Technology That ’ s Built to Crash Chances are your mobile phone company , as well as the makers of your DVD player and MP3 device , are all counting on their products to fail . Not too quickly , of course , or consumers wouldn ’ t stand for it — but frequently enough that you might find that when the built-in battery on your iPod dies , it costs far more to fix it than to replace it with a newer model . Or you find that the phone company e-mails you to tell you that you ’ re eligible for a free new phone , because yours is a whopping two years old . And appliance repair people say that while they might be fixing some machines that are 20 years old , they generally aren ’ t fixing the ones that are seven years old ; newer models are built to be thrown out . <hl> This is called planned obsolescence , and it is the business practice of planning for a product to be obsolete or unusable from the time it is created . <hl>", "hl_sentences": "The classic example of planned obsolescence is the nylon stocking . Women ’ s stockings — once an everyday staple of women ’ s lives – – get “ runs ” or “ ladders ” after a few wearings . This is called planned obsolescence , and it is the business practice of planning for a product to be obsolete or unusable from the time it is created .", "question": { "cloze_format": "The fact that your cell phone is using outdated technology within a year or two of purchase is an example of ____________.", "normal_format": "What is the fact that your cell phone is using outdated technology within a year or two of purchase an example of?", "question_choices": [ "the conflict perspective", "conspicuous consumption", "media", "planned obsolescence" ], "question_id": "fs-id2378797", "question_text": "The fact that your cell phone is using outdated technology within a year or two of purchase is an example of ____________." }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 0, "ans_text": "in the early stages of human societies" }, "bloom": "2", "hl_context": "While most people probably picture computers and cell phones when the subject of technology comes up , technology is not merely a product of the modern era . For example , fire and stone tools were important forms that technology developed during the Stone Age . Just as the availability of digital technology shapes how we live today , the creation of stone tools changed how premodern humans lived and how well they ate . From the first calculator , invented in 2400 B . C . E . Babylon in the form of an abacus , to the predecessor of the modern computer , created in 1882 by Charles Babbage , all of our technological innovations are advancements on previous iterations . <hl> And indeed , all aspects of our lives today are influenced by technology . <hl> <hl> In agriculture , the introduction of machines that can till , thresh , plant , and harvest greatly reduced the need for manual labor , which in turn meant there were fewer rural jobs , which led to the urbanization of society , as well as lowered birthrates because there was less need for large families to work the farms . <hl> In the criminal justice system , the ability to ascertain innocence through DNA testing has saved the lives of people on death row . The examples are endless : Technology plays a role in absolutely every aspect of our lives .", "hl_sentences": "And indeed , all aspects of our lives today are influenced by technology . In agriculture , the introduction of machines that can till , thresh , plant , and harvest greatly reduced the need for manual labor , which in turn meant there were fewer rural jobs , which led to the urbanization of society , as well as lowered birthrates because there was less need for large families to work the farms .", "question": { "cloze_format": "The history of technology began _________.", "normal_format": "When did the history of technology begin?", "question_choices": [ "in the early stages of human societies", "with the invention of the computer", "during the Renaissance", "during the 19th century" ], "question_id": "fs-id1743152", "question_text": "The history of technology began _________." }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 2, "ans_text": "Technology, media, and society are bound and cannot be separated." }, "bloom": "2", "hl_context": "<hl> Technology creates media . <hl> The comic book you bought your daughter at the drugstore is a form of media , as is the movie you rented for family night , the internet site you used to order dinner online , the billboard you passed on the way to get that dinner , and the newspaper you read while you were waiting to pick up your order . <hl> Without technology , media would not exist ; but remember , technology is more than just the media we are exposed to . <hl>", "hl_sentences": "Technology creates media . Without technology , media would not exist ; but remember , technology is more than just the media we are exposed to .", "question": { "cloze_format": "When it comes to technology, media, and society, the true statement is that ___ .", "normal_format": "When it comes to technology, media, and society, which of the following is true?", "question_choices": [ "Media influences technology, but not society. ", "Technology created media, but society has nothing to do with these.", "Technology, media, and society are bound and cannot be separated.", "Society influences media but is not connected to technology." ], "question_id": "fs-id1352100", "question_text": "When it comes to technology, media, and society, which of the following is true?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 1, "ans_text": "plant patent" }, "bloom": "3", "hl_context": "There is no one way of dividing technology into categories . Whereas once it might have been simple to classify innovations such as machine-based or drug-based or the like , the interconnected strands of technological development mean that advancement in one area might be replicated in dozens of others . For simplicity ’ s sake , we will look at how the U . S . Patent Office , which receives patent applications for nearly all major innovations worldwide , addresses patents . This regulatory body will patent three types of innovation . Utility patents are the first type . These are granted for the invention or discovery of any new and useful process , product , or machine , or for a significant improvement to existing technologies . The second type of patent is a design patent . Commonly conferred in architecture and industrial design , this means someone has invented a new and original design for a manufactured product . <hl> Plant patents , the final type , recognize the discovery of new plant types that can be asexually reproduced . <hl> <hl> While genetically modified food is the hot-button issue within this category , farmers have long been creating new hybrids and patenting them . <hl> A more modern example might be food giant Monsanto , which patents corn with built-in pesticide ( U . S . Patent and Trademark Office 2011 ) .", "hl_sentences": "Plant patents , the final type , recognize the discovery of new plant types that can be asexually reproduced . While genetically modified food is the hot-button issue within this category , farmers have long been creating new hybrids and patenting them .", "question": { "cloze_format": "If the U.S. Patent Office were to issue a patent for a new type of tomato that tastes like a jellybean, it would be issuing a _________ patent?", "normal_format": "If the U.S. Patent Office were to issue a patent for a new type of tomato that tastes like a jellybean, Which patent would it be issuing?", "question_choices": [ "utility patent", "plant patent", "design patent", "The U.S. Patent Office does not issue a patent for plants." ], "question_id": "fs-id1703872", "question_text": "If the U.S. Patent Office were to issue a patent for a new type of tomato that tastes like a jellybean, it would be issuing a _________ patent?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 3, "ans_text": "A breakthrough in one form of technology leads to a number of variations, and technological developments." }, "bloom": "1", "hl_context": "<hl> Anderson and Tushman ( 1990 ) suggest an evolutionary model of technological change , in which a breakthrough in one form of technology leads to a number of variations . <hl> Once those are assessed , a prototype emerges , and then a period of slight adjustments to the technology , interrupted by a breakthrough . For example , floppy disks were improved and upgraded , then replaced by Zip disks , which were in turn improved to the limits of the technology and were then replaced by flash drives . This is essentially a generational model for categorizing technology , in which first-generation technology is a relatively unsophisticated jumping-off point leading to an improved second generation , and so on .", "hl_sentences": "Anderson and Tushman ( 1990 ) suggest an evolutionary model of technological change , in which a breakthrough in one form of technology leads to a number of variations .", "question": { "cloze_format": "___ is the primary component of the evolutionary model of technological change.", "normal_format": "Which of the following is the primary component of the evolutionary model of technological change?", "question_choices": [ "Technology should not be subject to patenting.", "Technology and the media evolve together.", "Technology can be traced back to the early stages of human society.", "A breakthrough in one form of technology leads to a number of variations, and technological developments." ], "question_id": "fs-id1789391", "question_text": "Which of the following is the primary component of the evolutionary model of technological change?" }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 0, "ans_text": "The cable television program Dexter" }, "bloom": "1", "hl_context": "It is difficult to conceive of any one theory or theoretical perspective that can explain the variety of ways that people interact with technology and the media . Technology runs the gamut from the match you strike to light a candle all the way up to sophisticated nuclear power plants that might power the factory where that candle , was made . <hl> Media could refer to the television you watch , the ads wrapping the bus you take to work or school , or the magazines you flip through in a waiting room , not to mention all the forms of new media , including Twitter , Facebook , blogs , YouTube , and the like . <hl> Are media and technology critical to the forward march of humanity ? Are they pernicious capitalist tools that lead to the exploitation of workers worldwide ? Are they the magic bullet the world has been waiting for to level the playing field and raise the world ’ s poor out of extreme poverty ? Choose any opinion and you will find studies and scholars that agree with you – – and those who disagree . <hl> With the invention and widespread use of television in the mid - 20th century , newspaper circulation steadily dropped off , and in the 21st century , circulation has dropped further as more people turn to internet news sites and other forms of new media to stay informed . <hl> According to the Pew Research Center , 2009 saw an unprecedented drop in newspaper circulation – – down 10.6 percent from the year before ( Pew 2010 ) .", "hl_sentences": "Media could refer to the television you watch , the ads wrapping the bus you take to work or school , or the magazines you flip through in a waiting room , not to mention all the forms of new media , including Twitter , Facebook , blogs , YouTube , and the like . With the invention and widespread use of television in the mid - 20th century , newspaper circulation steadily dropped off , and in the 21st century , circulation has dropped further as more people turn to internet news sites and other forms of new media to stay informed .", "question": { "cloze_format": "___ is not a form of new media.", "normal_format": "Which of the following is not a form of new media?", "question_choices": [ "The cable television program Dexter", "Wikipedia", "Facebook", "A cooking blog written by Rachel Ray" ], "question_id": "fs-id1532691", "question_text": "Which of the following is not a form of new media?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 3, "ans_text": "violent video games lead to an increase in aggressive thought and behavior" }, "bloom": null, "hl_context": "<hl> Ultimately , repeated exposure to this kind of violence leads to increased expectations regarding violence as a solution , increased violent behavioral scripts , and making violent behavior more cognitively accessible ( Anderson 2003 ) . <hl> <hl> In short , people who play a lot of these games find it easier to imagine and access violent solutions than nonviolent ones , and are less socialized to see violence as a negative . <hl> <hl> While these facts do not mean there is no role for video games , it should give players pause . <hl> Clearly , when it comes to violence in gaming , it ’ s not “ only a game . ” Children ’ s play has often involved games of aggression — from cowboys and Indians , to cops and robbers , to water-balloon fights . Many articles report on the controversy surrounding the linkage between violent video games and violent behavior . Are these charges true ? <hl> Psychologists Anderson and Bushman ( 2001 ) reviewed 40 - plus years of research on the subject and , in 2003 , determined that there are causal linkages between violent video game use and aggression . <hl> <hl> They found that children who had just played a violent video game demonstrated an immediate increase in hostile or aggressive thoughts , an increase in aggressive emotions , and physiological arousal that increased the chances of acting out aggressive behavior ( Anderson 2003 ) . <hl>", "hl_sentences": "Ultimately , repeated exposure to this kind of violence leads to increased expectations regarding violence as a solution , increased violent behavioral scripts , and making violent behavior more cognitively accessible ( Anderson 2003 ) . In short , people who play a lot of these games find it easier to imagine and access violent solutions than nonviolent ones , and are less socialized to see violence as a negative . While these facts do not mean there is no role for video games , it should give players pause . Psychologists Anderson and Bushman ( 2001 ) reviewed 40 - plus years of research on the subject and , in 2003 , determined that there are causal linkages between violent video game use and aggression . They found that children who had just played a violent video game demonstrated an immediate increase in hostile or aggressive thoughts , an increase in aggressive emotions , and physiological arousal that increased the chances of acting out aggressive behavior ( Anderson 2003 ) .", "question": { "cloze_format": "Research regarding video game violence suggests that _________.", "normal_format": "What does research regarding video game violence suggest?", "question_choices": [ "boys who play violent video games become more aggressive, but girls do not", "girls who play violent video games become more aggressive, but boys do not", "violent video games have no connection to aggressive behavior", "violent video games lead to an increase in aggressive thought and behavior" ], "question_id": "fs-id1278766", "question_text": "Research regarding video game violence suggests that _________." }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 0, "ans_text": "media " }, "bloom": "1", "hl_context": "Technology creates media . <hl> The comic book you bought your daughter at the drugstore is a form of media , as is the movie you rented for family night , the internet site you used to order dinner online , the billboard you passed on the way to get that dinner , and the newspaper you read while you were waiting to pick up your order . <hl> Without technology , media would not exist ; but remember , technology is more than just the media we are exposed to .", "hl_sentences": "The comic book you bought your daughter at the drugstore is a form of media , as is the movie you rented for family night , the internet site you used to order dinner online , the billboard you passed on the way to get that dinner , and the newspaper you read while you were waiting to pick up your order .", "question": { "cloze_format": "Comic books, Wikipedia, MTV, and a commercial for Coca-Cola are all examples of ___ .", "normal_format": "What are comic books, Wikipedia, MTV, and a Coca-Cola commercial all examples of?", "question_choices": [ "media ", "symbolic interaction perspective", "e-readiness", "the digital divide" ], "question_id": "fs-id1490378", "question_text": "Comic books, Wikipedia, MTV, and a commercial for Coca-Cola are all examples of:" }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 1, "ans_text": "technological diffusion" }, "bloom": "1", "hl_context": "<hl> Technological globalization is impacted in large part by technological diffusion , the spread of technology across borders . <hl> In the last two decades , there has been rapid improvement in the spread of technology to peripheral and semi-peripheral nations , and a 2008 World Bank report discusses both the benefits and ongoing challenges of this diffusion . In general , the report found that technological progress and economic growth rates were linked , and that the rise in technological progress has helped improve the situations of many living in absolute poverty ( World Bank 2008 ) . The report recognizes that rural and low-tech products such as corn can benefit from new technological innovations , and that , conversely , technologies like mobile banking can aid those whose rural existence consists of low-tech market vending . In addition , technological advances in areas like mobile phones can lead to competition , lowered prices , and concurrent improvements in related areas such as mobile banking and information sharing .", "hl_sentences": "Technological globalization is impacted in large part by technological diffusion , the spread of technology across borders .", "question": { "cloze_format": "When Japanese scientists develop a new vaccine for swine flu and offer that technology to American pharmaceutical companies, __________ has taken place.", "normal_format": "When Japanese scientists develop a new vaccine for swine flu and offer that technology to American pharmaceutical companies, which of the following has taken place?", "question_choices": [ "media globalization", "technological diffusion", "monetizing", "planned obsolescence" ], "question_id": "fs-id15500251", "question_text": "When Japanese scientists develop a new vaccine for swine flu and offer that technology to American pharmaceutical companies, __________ has taken place." }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 1, "ans_text": "The creation of local monopolies" }, "bloom": "1", "hl_context": "<hl> Cultural and ideological bias are not the only risks of media globalization . <hl> <hl> In addition to the risk of cultural imperialism and the loss of local culture , other problems come with the benefits of a more interconnected globe . <hl> One risk is the potential censoring by national governments that let in only the information and media they feel serves their message , as can be seen in China . In addition , core nations such as the United States risk the use of international media such as the internet to circumvent local laws against socially deviant and dangerous behaviors such as gambling , child pornography , and the sex trade . Offshore or international web sites allow U . S . citizens ( as well as others ) to seek out whatever illegal ( in the United States ) or illicit information they want , from 24 - hour online gambling sites that do not require proof of age , to sites that sell child pornography . These examples illustrate the societal risks of unfettered information flow .", "hl_sentences": "Cultural and ideological bias are not the only risks of media globalization . In addition to the risk of cultural imperialism and the loss of local culture , other problems come with the benefits of a more interconnected globe .", "question": { "cloze_format": "___ is not a risk of media globalization.", "normal_format": "Which of the following is not a risk of media globalization?", "question_choices": [ "The creation of cultural and ideological biases", "The creation of local monopolies", "The risk of cultural imperialism", "The loss of local culture" ], "question_id": "fs-id1432720", "question_text": "Which of the following is not a risk of media globalization?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 0, "ans_text": "China" }, "bloom": "1", "hl_context": "<hl> With sites like Twitter , Facebook and YouTube blocked in China , the nation ’ s internet users – – some 500 million strong in 2011 – – turn to local media companies for their needs . <hl> Renren.com is China ’ s answer to Facebook . Perhaps more importantly from a social-change perspective , Sina Weibo is China ’ s version of Twitter . Microblogging , or weibo , acts like Twitter in that users can post short messages that can be read by their subscribers . And because these services move so quickly and with such wide scope , it is difficult for government overseers to keep up . This tool was used to criticize government response to a deadly rail crash and to protest a chemical plant . It was also credited with the government ’ s decision to report more accurately on the air pollution in Beijing , which occurred after a high-profile campaign by a well-known property developer ( Pierson 2012 ) .", "hl_sentences": "With sites like Twitter , Facebook and YouTube blocked in China , the nation ’ s internet users – – some 500 million strong in 2011 – – turn to local media companies for their needs .", "question": { "cloze_format": "The government of __________ blocks citizens’ access to popular new media sites like Facebook, YouTube, and Twitter.", "normal_format": "The government of which country blocks citizens’ access to popular new media sites like Facebook, YouTube, and Twitter?", "question_choices": [ "China", "India", "Afghanistan", "Australia" ], "question_id": "fs-id14017951", "question_text": "The government of __________ blocks citizens’ access to popular new media sites like Facebook, YouTube, and Twitter." }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 3, "ans_text": "panoptic surveillance" }, "bloom": "3", "hl_context": "Social scientists take the idea of the surveillance society so seriously that there is an entire journal devoted to its study , Surveillance and Society . <hl> The panoptic surveillance envisioned by Jeremy Bentham and later analyzed by Michel Foucault ( 1975 ) is increasingly realized in the form of technology used to monitor our every move . <hl> <hl> This surveillance was imagined as a form of constant monitoring in which the observation posts are decentralized and the observed is never communicated with directly . <hl> <hl> Today , digital security cameras capture our movements , observers can track us through our cell phones , and police forces around the world use facial-recognition software . <hl>", "hl_sentences": "The panoptic surveillance envisioned by Jeremy Bentham and later analyzed by Michel Foucault ( 1975 ) is increasingly realized in the form of technology used to monitor our every move . This surveillance was imagined as a form of constant monitoring in which the observation posts are decentralized and the observed is never communicated with directly . Today , digital security cameras capture our movements , observers can track us through our cell phones , and police forces around the world use facial-recognition software .", "question": { "cloze_format": "A parent secretly monitoring the babysitter through the use of GPS, site blocker, and nanny cam is a good example of ___ .", "normal_format": "What is a parent secretly monitoring the babysitter through the use of GPS, site blocker, and nanny cam a good example of?", "question_choices": [ "the social construction of reality", "technophilia", "a neo-Luddite", "panoptic surveillance" ], "question_id": "fs-id1324789", "question_text": "A parent secretly monitoring the babysitter through the use of GPS, site blocker, and nanny cam is a good example of:" }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 0, "ans_text": "social construction of reality" }, "bloom": null, "hl_context": "<hl> Meanwhile , media create and spread symbols that become the basis for our shared understanding of society . <hl> <hl> Theorists working in the interactionist perspective focus on this social construction of reality , an ongoing process in which people subjectively create and understand reality . <hl> <hl> Media constructs our reality in a number of ways . <hl> For some , the people they watch on a screen can become a primary group , meaning the small informal groups of people who are closest to them . For many others , media becomes a reference group : a group that influences an individual and to which an individual compares himself , and by which we judge our successes and failures . We might do very well without an Android smartphone , until we see characters using it on our favorite television show or our classmates whipping one out between classes .", "hl_sentences": "Meanwhile , media create and spread symbols that become the basis for our shared understanding of society . Theorists working in the interactionist perspective focus on this social construction of reality , an ongoing process in which people subjectively create and understand reality . Media constructs our reality in a number of ways .", "question": { "cloze_format": "The use of Facebook to create an online persona by only posting images that match your ideal self exemplifies the_____________ that can occur in forms of new media.", "normal_format": "What exemplifies the use of Facebook to create an online persona by only posting images that match your ideal self that can occur in forms of new media? ", "question_choices": [ "social construction of reality", "cyberfeminism ", "market segmentation", "referencing" ], "question_id": "fs-id1730576", "question_text": "The use of Facebook to create an online persona by only posting images that match your ideal self exemplifies the_____________ that can occur in forms of new media." }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 1, "ans_text": "technophiles; Luddites" }, "bloom": "1", "hl_context": "Technology itself may act as a symbol for many . The kind of computer you own , the kind of car you drive , whether or not you can afford the latest Apple product — these serve as a social indicator of wealth and status . <hl> Neo-Luddites are people who see technology as symbolizing the coldness and alienation of modern life . <hl> <hl> But for technophiles , technology symbolizes the potential for a brighter future . <hl> For those adopting an ideological middle ground , technology might symbolize status ( in the form of a massive flat-screen television ) or failure ( in owning a basic old mobile phone with no bells or whistles ) .", "hl_sentences": "Neo-Luddites are people who see technology as symbolizing the coldness and alienation of modern life . But for technophiles , technology symbolizes the potential for a brighter future .", "question": { "cloze_format": "_________ tend to be more pro-technology, while _______ view technology as a symbol of the coldness of modern life.", "normal_format": "Which tend to be more pro-technology, while which view technology as a symbol of the coldness of modern life?", "question_choices": [ "Luddites; technophiles", "technophiles; Luddites", "cyberfeminists; technophiles", "liberal feminists; conflict theorists" ], "question_id": "fs-id1770471", "question_text": "_________ tend to be more pro-technology, while _______ view technology as a symbol of the coldness of modern life." }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 2, "ans_text": "the way that various forms of media socialize users " }, "bloom": "1", "hl_context": "These are some of the questions that interest sociologists . How might we examine these issues from a sociological perspective ? <hl> A functionalist would probably focus on what social purposes technology and media serve . <hl> For example , the web is both a form of technology and of media , and it links individuals and nations in a communication network that facilitates both small family discussions and global trade networks . <hl> A functionalist would also be interested in the manifest functions of media and technology , as well as their role in social dysfunction . <hl> Someone applying the conflict perspective would probably focus on the systematic inequality created by differential access to media and technology . For example , how can middle-class Americans be sure the news they hear is an objective account of reality , unsullied by monied political interests ? Someone applying the interactionist perspective to technology and the media might seek to understand the difference between the real lives we lead and the reality depicted on “ reality ” television shows , such as Jersey Shore . Throughout this chapter , we will use our sociological imagination to explore how media and technology impact society .", "hl_sentences": "A functionalist would probably focus on what social purposes technology and media serve . A functionalist would also be interested in the manifest functions of media and technology , as well as their role in social dysfunction .", "question": { "cloze_format": "When it comes to media and technology, a functionalist would focus on ___.", "normal_format": "What would a functionalist focus on when it comes to media and technology?", "question_choices": [ "the symbols created and reproduced by the media", "the association of technology and technological skill with men", "the way that various forms of media socialize users ", "the digital divide between the technological haves and have-nots" ], "question_id": "fs-id1269309", "question_text": "When it comes to media and technology, a functionalist would focus on:" }, "references_are_paraphrase": null } ]
8
8.1 Technology Today It is easy to look at the latest sleek tiny Apple product and think that technology is only recently a part of our world. But from the steam engine to the most cutting-edge robotic surgery tools, technology describes the application of science to address the problems of daily life. We might look back at the enormous and clunky computers of the 1970s that had about as much storage as an iPod Shuffle and roll our eyes in disbelief. But chances are 30 years from now our skinny laptops and MP3 players will look just as archaic. What Is Technology? While most people probably picture computers and cell phones when the subject of technology comes up, technology is not merely a product of the modern era. For example, fire and stone tools were important forms that technology developed during the Stone Age. Just as the availability of digital technology shapes how we live today, the creation of stone tools changed how premodern humans lived and how well they ate. From the first calculator, invented in 2400 B.C.E. Babylon in the form of an abacus, to the predecessor of the modern computer, created in 1882 by Charles Babbage, all of our technological innovations are advancements on previous iterations. And indeed, all aspects of our lives today are influenced by technology. In agriculture, the introduction of machines that can till, thresh, plant, and harvest greatly reduced the need for manual labor, which in turn meant there were fewer rural jobs, which led to the urbanization of society, as well as lowered birthrates because there was less need for large families to work the farms. In the criminal justice system, the ability to ascertain innocence through DNA testing has saved the lives of people on death row. The examples are endless: Technology plays a role in absolutely every aspect of our lives. Technological Inequality As with any improvement to human society, not everyone has equal access. Technology, in particular, often creates changes that lead to ever greater inequalities. In short, the gap gets wider faster. This technological stratification has led to a new focus on ensuring better access for all. There are two forms of technological stratification. The first is differential class-based access to technology in the form of the digital divide. This digital divide has led to the second form, a knowledge gap , which is, as it sounds, an ongoing and increasing gap in information for those who have less access to technology. Simply put, students in well-funded schools receive more exposure to technology than students in poorly funded schools. Those students with more exposure gain more proficiency, making them far more marketable in an increasingly technology-based job market, leaving our society divided into those with technological knowledge and those without. Even as we improve access, we have failed to address an increasingly evident gap in e-readiness , the ability to sort through, interpret, and process knowledge (Sciadas 2003). Since the beginning of the millennium, social science researchers have tried to bring attention to the digital divide , the uneven access to technology along race, class, and geographic lines. The term became part of the common lexicon in 1996, when then Vice President Al Gore used it in a speech. This was the point when personal computer use shifted dramatically, from 300,000 users in 1991 to more than 10 million users by 1996 (Rappaport 2009). In part, the issue of the digital divide had to do with communities that received infrastructure upgrades that enabled high-speed internet access, upgrades that largely went to affluent urban and suburban areas, leaving out large swaths of the country. At the end of the 20th century, technology access was also a big part of the school experience for those whose communities could afford it. Early in the millennium, poorer communities had little or no technology access, while well-off families had personal computers at home and wired classrooms in their schools. In the 2000s, however, the prices for low-end computers dropped considerably, and it appeared the digital divide was naturally ending. And while it is true that internet usage, even among those with low annual incomes, continues to grow, it would be overly simplistic to say that the digital divide has been completely resolved. In fact, new data from the Pew Research Center (2011) suggest the emergence of a new divide. As technological devices gets smaller and more mobile, larger percentages of minority groups (such as Latinos and African Americans) are using their phones to connect to the internet. In fact, about 50 percent of people in these minority groups connect to the web via such devices, whereas only one-third of whites do (Washington 2011). And while it might seem that the internet is the internet, regardless of how you get there, there’s a notable difference. Tasks like updating a résumé or filling out a job application are much harder on a cell phone than on a wired computer in the home. As a result, the digital divide might not mean access to computers or the internet, but rather access to the kind of online technology that allows for empowerment, not just entertainment (Washington 2011). Mossberger, Tolbert, and Gilbert (2006) demonstrated that the majority of the digital divide for black Americans could be explained by demographic and community-level characteristics, such as socioeconomic status and geographic location. For the Latino population, ethnicity alone, regardless of economics or geography, seemed to limit technology use. Liff and Shepard (2004) found that although the gender digital divide has decreased in the sense of access to technology, it remained in the sense that women, who are accessing technology shaped primarily by male users, feel less confident in their internet skills and have less internet access at both work and home. Finally, Guillen and Suarez (2005) found that the global digital divide resulted from both the economic and sociopolitical characteristics of countries. Sociology in the Real World Planned Obsolescence: Technology That’s Built to Crash Chances are your mobile phone company, as well as the makers of your DVD player and MP3 device, are all counting on their products to fail. Not too quickly, of course, or consumers wouldn’t stand for it—but frequently enough that you might find that when the built-in battery on your iPod dies, it costs far more to fix it than to replace it with a newer model. Or you find that the phone company e-mails you to tell you that you’re eligible for a free new phone, because yours is a whopping two years old. And appliance repair people say that while they might be fixing some machines that are 20 years old, they generally aren’t fixing the ones that are seven years old; newer models are built to be thrown out. This is called planned obsolescence , and it is the business practice of planning for a product to be obsolete or unusable from the time it is created. To some extent, this is a natural extension of new and emerging technologies. After all, who is going to cling to an enormous and slow desktop computer from 2000 when a few hundred dollars can buy one that is significantly faster and better? But the practice is not always so benign. The classic example of planned obsolescence is the nylon stocking. Women’s stockings—once an everyday staple of women’s lives––get “runs” or “ladders” after a few wearings. This requires the stockings to be discarded and new ones purchased. Not surprisingly, the garment industry did not invest heavily in finding a rip-proof fabric; it was in their best interest that their product be regularly replaced. Those who use Microsoft Windows might feel that they, like the women who purchase endless pairs of stockings, are victims of planned obsolescence. Every time Windows releases a new operating system, there are typically not many changes that consumers feel they must have. However, the software programs are upwardly compatible only. This means that while the new versions can read older files, the old version cannot read the newer ones. In short order, those who have not upgraded find themselves unable to open files sent by colleagues or friends, and usually wind up upgrading as well. Ultimately, whether you are getting rid of your old product because you are being offered a shiny new free one (like the latest smartphone model), or because it costs more to fix than to replace (like the iPod model), or because not doing so leaves you out of the loop (like the Windows model), the result is the same. It might just make you nostalgic for your old Sony Walkman and VCR. 8.2 Media and Technology in Society Technology and the media are interwoven, and neither can be separated from contemporary society in most core and semi-peripheral nations. Media is a term that refers to all print, digital, and electronic means of communication. From the time the printing press was created (and even before), technology has influenced how and where information is shared. Today, it is impossible to discuss media and the ways that societies communicate without addressing the fast-moving pace of technology. Twenty years ago, if you wanted to share news of your baby’s birth or a job promotion, you phoned or wrote letters. You might tell a handful of people, but probably you wouldn’t call up several hundred, including your old high school chemistry teacher, to let them know. Now, by tweeting or posting your big news, the circle of communication is wider than ever. Therefore, when we talk about how societies engage with technology we must take media into account, and vice versa. Technology creates media. The comic book you bought your daughter at the drugstore is a form of media, as is the movie you rented for family night, the internet site you used to order dinner online, the billboard you passed on the way to get that dinner, and the newspaper you read while you were waiting to pick up your order. Without technology, media would not exist; but remember, technology is more than just the media we are exposed to. Categorizing Technology There is no one way of dividing technology into categories. Whereas once it might have been simple to classify innovations such as machine-based or drug-based or the like, the interconnected strands of technological development mean that advancement in one area might be replicated in dozens of others. For simplicity’s sake, we will look at how the U.S. Patent Office, which receives patent applications for nearly all major innovations worldwide, addresses patents. This regulatory body will patent three types of innovation. Utility patents are the first type. These are granted for the invention or discovery of any new and useful process, product, or machine, or for a significant improvement to existing technologies. The second type of patent is a design patent . Commonly conferred in architecture and industrial design, this means someone has invented a new and original design for a manufactured product. Plant patents , the final type, recognize the discovery of new plant types that can be asexually reproduced. While genetically modified food is the hot-button issue within this category, farmers have long been creating new hybrids and patenting them. A more modern example might be food giant Monsanto, which patents corn with built-in pesticide (U.S. Patent and Trademark Office 2011). Anderson and Tushman (1990) suggest an evolutionary model of technological change , in which a breakthrough in one form of technology leads to a number of variations. Once those are assessed, a prototype emerges, and then a period of slight adjustments to the technology, interrupted by a breakthrough. For example, floppy disks were improved and upgraded, then replaced by Zip disks, which were in turn improved to the limits of the technology and were then replaced by flash drives. This is essentially a generational model for categorizing technology, in which first-generation technology is a relatively unsophisticated jumping-off point leading to an improved second generation, and so on. Types of Media and Technology Media and technology have evolved hand in hand, from early print to modern publications, from radio to television to film. New media emerge constantly, such as we see in the online world. Print Newspaper Early forms of print media, found in ancient Rome, were hand-copied onto boards and carried around to keep the citizenry informed. With the invention of the printing press, the way that people shared ideas changed, as information could be mass produced and stored. For the first time, there was a way to spread knowledge and information more efficiently; many credit this development as leading to the Renaissance and ultimately the Age of Enlightenment. This is not to say that newspapers of old were more trustworthy than the Weekly World News and National Enquirer are today. Sensationalism abounded, as did censorship that forbade any subjects that would incite the populace. The invention of the telegraph, in the mid-1800s, changed print media almost as much as the printing press. Suddenly information could be transmitted in minutes. As the 19th century became the 20th, American publishers such as Hearst redefined the world of print media and wielded an enormous amount of power to socially construct national and world events. Of course, even as the media empires of William Randolph Hearst and Joseph Pulitzer were growing, print media also allowed for the dissemination of countercultural or revolutionary materials. Internationally, Vladimir Lenin’s Irksa ( The Spark ) newspaper was published in 1900 and played a role in Russia’s growing communist movement (World Association of Newspapers 2004). With the invention and widespread use of television in the mid-20th century, newspaper circulation steadily dropped off, and in the 21st century, circulation has dropped further as more people turn to internet news sites and other forms of new media to stay informed. According to the Pew Research Center, 2009 saw an unprecedented drop in newspaper circulation––down 10.6 percent from the year before (Pew 2010). This shift away from newspapers as a source of information has profound effects on societies. When the news is given to a large diverse conglomerate of people, it must (to appeal to them and keep them subscribing) maintain some level of broad-based reporting and balance. As newspapers decline, news sources become more fractured, so that the audience can choose specifically what it wants to hear and what it wants to avoid. Television and Radio Radio programming obviously preceded television, but both shaped people’s lives in much the same way. In both cases, information (and entertainment) could be enjoyed at home, with a kind of immediacy and community that newspapers could not offer. For instance, many older Americans might remember when they heard on the radio that Pearl Harbor had been bombed, or when they saw on the television that President John F. Kennedy had been shot. Even though people were in their own homes, media allowed them to share these moments in real time. This same kind of separate-but-communal approach occurred with entertainment too. School-aged children and office workers gathered to discuss the previous night’s installment of a serial television or radio show. Right up through the 1970s, American television was dominated by three major networks (ABC, CBS, and NBC) that competed for ratings and advertising dollars. They also exerted a lot of control over what was being watched. Public television, in contrast, offered an educational nonprofit alternative to the sensationalization of news spurred by the network competition for viewers and advertising dollars. Those sources—PBS (Public Broadcasting Service), the BBC (British Broadcasting Company), and CBC (Canadian Broadcasting Company)—garnered a worldwide reputation for quality programming and a global perspective. Al Jazeera, the Arabic independent news station, has joined this group as a similar media force that broadcasts to people worldwide. The impact of television on American society is hard to overstate. By the late 1990s, 98 percent of U.S. homes had at least one television set, and the average American watched between two and a half to five hours of television daily. All this television has a powerful socializing effect, with these forms of visual media providing reference groups while reinforcing social norms, values, and beliefs. Film The film industry took off in the 1930s, when color and sound were first integrated into feature films. Like television, early films were unifying for society: As people gathered in theaters to watch new releases, they would laugh, cry, and be scared together. Movies also act as time capsules or cultural touchstones for society. From tough-talking Clint Eastwood to the biopic of Facebook founder and Harvard dropout Mark Zuckerberg, movies illustrate society’s dreams, fears, and experiences. While many Americans consider Hollywood the epicenter of moviemaking, India’s Bollywood actually produces more films per year, speaking to the cultural aspirations and norms of Indian society. New Media New media encompasses all interactive forms of information exchange. These include social networking sites, blogs, podcasts, wikis, and virtual worlds. Clearly, the list grows almost daily. New media tends to level the playing field in terms of who is constructing it, i.e., creating, publishing, distributing, and accessing information (Lievrouw and Livingston 2006), as well as offering alternative forums to groups unable to gain access to traditional political platforms, such as groups associated with the Arab Spring protests (van de Donk et al. 2004). However, there is no guarantee of the accuracy of the information offered. In fact, the immediacy of new media coupled with the lack of oversight means that we must be more careful than ever to ensure our news is coming from accurate sources. Sociology in the Real World Violence in Media and Video Games: Does It Matter? A glance through popular video game and movie titles geared toward children and teens shows the vast spectrum of violence that is displayed, condoned, and acted out. It may hearken back to Popeye and Bluto beating up on each other, or Wile E. Coyote trying to kill and devour the Road Runner, but the graphics and actions have moved far beyond Acme’s cartoon dynamite. As a way to guide parents in their programming choices, the motion picture industry put a rating system in place in the 1960s. But new media—video games in particular—proved to be uncharted territory. In 1994, the Entertainment Software Rating Board (ERSB) set a ratings system for games that addressed issues of violence, sexuality, drug use, and the like. California took it a step further by making it illegal to sell video games to underage buyers. The case led to a heated debate about personal freedoms and child protection, and in 2011, the U.S. Supreme Court ruled against the California law, stating it violated freedom of speech (ProCon 2012). Children’s play has often involved games of aggression—from cowboys and Indians, to cops and robbers, to water-balloon fights. Many articles report on the controversy surrounding the linkage between violent video games and violent behavior. Are these charges true? Psychologists Anderson and Bushman (2001) reviewed 40-plus years of research on the subject and, in 2003, determined that there are causal linkages between violent video game use and aggression. They found that children who had just played a violent video game demonstrated an immediate increase in hostile or aggressive thoughts, an increase in aggressive emotions, and physiological arousal that increased the chances of acting out aggressive behavior (Anderson 2003). Ultimately, repeated exposure to this kind of violence leads to increased expectations regarding violence as a solution, increased violent behavioral scripts, and making violent behavior more cognitively accessible (Anderson 2003). In short, people who play a lot of these games find it easier to imagine and access violent solutions than nonviolent ones, and are less socialized to see violence as a negative. While these facts do not mean there is no role for video games, it should give players pause. Clearly, when it comes to violence in gaming, it’s not “only a game.” Product Advertising Can You Hear Me Now? I’m Lovin’ It. The Verizon Halftime Report. Companies use advertising to sell to us, but the way they reach us is changing. Increasingly, synergistic advertising practices ensure you are receiving the same message from a variety of sources. For example, you may see billboards for Miller on your way to a stadium, sit down to watch a game preceded by an MGD commercial on the big screen, and watch a halftime ad in which people are frequently shown holding up the trademark bottles. Chances are you can guess which brand of beer is for sale at the concession stand. Advertising has changed, as technology and media have allowed consumers to bypass traditional advertising venues. From the invention of the remote control, which allows us to ignore television advertising without leaving our seats, to recording devices that let us watch television programs but skip the ads, conventional advertising is on the wane. And print media is no different. Advertising revenue in newspapers and on television fell significantly in 2009, showing that companies need new ways of getting their message to consumers. One model companies are considering to address this advertising downturn uses the same philosophy as celebrity endorsements, just on a different scale. Companies are hiring college students to be their on-campus representatives, looking for popular students involved in high-profile activities like sports, fraternities, and music. The marketing team is betting that if we buy perfume because Beyoncé tells us to, we’ll also choose our cell phone or smoothie if a popular student encourages that brand. According to an article in the New York Times , fall semester 2011 saw an estimated 10,000 American college students working on campus as brand ambassadors for products from Red Bull energy drinks to Hewlett-Packard computers (Singer 2011). As the companies figure it, college students will trust one source of information above all: other students. Homogenization and Fragmentation Despite the variety of media at hand, the mainstream news and entertainment you enjoy are increasingly homogenized. Research by McManus (1995) suggests that different news outlets all tell the same stories, using the same sources, resulting in the same message, presented with only slight variations. So whether you are reading the New York Times or the CNN’s web site, the coverage of national events like a major court case or political issue will likely be the same. Simultaneous to this homogenization among the major news outlets, the opposite process is occurring in the newer media streams. With so many choices, people increasingly “customize” their news experience, minimizing “chance encounters” with information that does not jive with their worldview (Prior 2005). For instance, those who are staunchly Republican can avoid centrist or liberal-leaning cable news shows and web sites that would show Democrats in a favorable light. They know to seek out Fox News over MSNBC, just as Democrats know to do the opposite. Further, people who want to avoid politics completely can choose to visit web sites that deal only with entertainment or that will keep them up to date on sports scores. They have an easy way to avoid information they do not wish to hear. 8.3 Global Implications Technology, and increasingly media, has always driven globalization. Thomas Friedman (2005) in a landmark publication, identified several ways in which technology “flattened” the globe and contributed to our global economy. The first edition of The World Is Flat , written in 2005, posits that core economic concepts were changed by personal computing and high-speed internet. Access to these two technological shifts has allowed core-nation corporations to recruit workers in call centers located in China or India. Using examples like a Midwestern American woman who runs a business from her home via the call centers of Bangalore, India, Friedman warns that this new world order will exist whether core-nation businesses are ready or not, and that in order to keep its key economic role in the world, the United States will need to pay attention to how it prepares workers of the 21st century for this dynamic. Of course not everyone agrees with Friedman’s theory. Many economists pointed out that, in reality, innovation, economic activity, and population still gather in geographically attractive areas, continuing to create economic peaks and valleys, which are by no means flattened out to mean equality for all. China’s hugely innovative and powerful cities of Shanghai and Beijing are worlds away from the rural squalor of the country’s poorest denizens. It is worth noting that Friedman is an economist, not a sociologist. His work focuses on the economic gains and risks this new world order entails. In this section, we will look more closely at how media globalization and technological globalization play out in a sociological perspective. As the names suggest, media globalization is the worldwide integration of media through the cross-cultural exchange of ideas, while technological globalization refers to the cross-cultural development and exchange of technology. Media Globalization Lyons (2005) suggests that multinational corporations are the primary vehicle of media globalization, and these corporations control global mass-media content and distribution (Compaine 2005). It is true, when looking at who controls which media outlets, that there are fewer independent news sources as larger and larger conglomerates develop. The United States offers about 1,500 newspapers, 2,600 book publishers, and an equal number of television stations, plus 6,000 magazines and a whopping 10,000 radio outlets (Bagdikian 2004). On the surface, there is endless opportunity to find diverse media outlets. But the numbers are misleading. In 1983, a mere 50 corporations owned the bulk of mass-media outlets. Today, those 50 corporations have morphed into only six conglomerates (large companies consisting of many seemingly unrelated businesses). These conglomerates control most of the United States’ mass-media vehicles. These six corporations are Time Warner, Disney, Viacom, General Electric, and the foreign-headquartered News Corporation (Australia) and Bertelsmann (Germany). Because the readers of the Daily News in one town might not care that their newspaper is owned by the same folks who own the Tribune across the country, why does it matter? Monopolies matter because less competition typically means consumers are less well served since dissenting opinions or diverse viewpoints are less likely to be found. While some social scientists predicted that the increase in media forms would create a global village (McLuhan 1964), current research suggests that the public sphere accessing the global village will tend to be rich, Caucasoid, and English-speaking (Jan 2009). As shown by the spring 2011 uprisings throughout the Arab world, technology really does offer a window into the news of the world. For example, here in the United States we saw internet updates of Egyptian events in real time, with people tweeting, posting, and blogging on the ground in Tahirir Square. Still, there is no question that the exchange of technology from core nations to peripheral and semi-peripheral ones leads to a number of complex issues. For instance, someone using a conflict theorist approach might focus on how much political ideology and cultural colonialism occurs with technological growth. In theory at least, technological innovations are ideology-free; a fiber optic cable is the same in a Muslim country as a secular one, a communist country or a capitalist one. But those who bring technology to less developed nations—whether they are nongovernment organizations, businesses, or governments—usually have an agenda. A functionalist, in contrast, might focus on the ways that technology creates new ways to share information about successful crop-growing programs, or on the economic benefits of opening a new market for cell phone use. Either way, there are cultural and societal assumptions and norms being delivered along with those high-speed wires. Cultural and ideological bias are not the only risks of media globalization. In addition to the risk of cultural imperialism and the loss of local culture, other problems come with the benefits of a more interconnected globe. One risk is the potential censoring by national governments that let in only the information and media they feel serves their message, as can be seen in China. In addition, core nations such as the United States risk the use of international media such as the internet to circumvent local laws against socially deviant and dangerous behaviors such as gambling, child pornography, and the sex trade. Offshore or international web sites allow U.S. citizens (as well as others) to seek out whatever illegal (in the United States) or illicit information they want, from 24-hour online gambling sites that do not require proof of age, to sites that sell child pornography. These examples illustrate the societal risks of unfettered information flow. China and the Internet: An Uncomfortable Friendship In the United States, the internet is used to access illegal gambling and pornography sites, as well as to research stocks, crowd-source what car to buy, or keep in touch with childhood friends. Can we allow one or more of those activities, while restricting the rest? And who decides what needs restricting? In a country with democratic principles and an underlying belief in free-market capitalism, the answer is decided in the court system. But globally, the questions––and the government’s responses––are very different. China is in many ways the global poster child for the uncomfortable relationship between internet freedom and government control. A country with a tight rein on the dissemination of information, China has long worked to suppress what it calls “harmful information,” including dissent concerning government politics, dialogue about China’s role in Tibet, or criticism of the government’s handling of events. With sites like Twitter, Facebook and YouTube blocked in China, the nation’s internet users––some 500 million strong in 2011––turn to local media companies for their needs. Renren.com is China’s answer to Facebook. Perhaps more importantly from a social-change perspective, Sina Weibo is China’s version of Twitter. Microblogging, or weibo , acts like Twitter in that users can post short messages that can be read by their subscribers. And because these services move so quickly and with such wide scope, it is difficult for government overseers to keep up. This tool was used to criticize government response to a deadly rail crash and to protest a chemical plant. It was also credited with the government’s decision to report more accurately on the air pollution in Beijing, which occurred after a high-profile campaign by a well-known property developer (Pierson 2012). There is no question of China’s authoritarian government ruling over this new form of internet communication. The nation blocks the use of certain terms, such as human rights, and passes new laws that require people to register with their real names, making it more dangerous to criticize government actions. Indeed, 56-year-old microblogger Wang Lihong was recently sentenced to nine months in prison for “stirring up trouble,” as her government described her work helping people with government grievances (Bristow 2011). But the government cannot shut down this flow of information completely. Foreign companies, seeking to engage with the increasingly important Chinese consumer market, have their own accounts: the NBA has more than 5 million followers, and Tom Cruise’s Weibo account boasts almost 3 million followers (Zhang 2011). The government, too, uses Weibo to get its own message across. As 2012 progresses, China’s approach to social media and the freedoms it offers will be watched anxiously––on Sina Weibo and beyond––by the rest of the world. Technological Globalization Technological globalization is impacted in large part by technological diffusion , the spread of technology across borders. In the last two decades, there has been rapid improvement in the spread of technology to peripheral and semi-peripheral nations, and a 2008 World Bank report discusses both the benefits and ongoing challenges of this diffusion. In general, the report found that technological progress and economic growth rates were linked, and that the rise in technological progress has helped improve the situations of many living in absolute poverty (World Bank 2008). The report recognizes that rural and low-tech products such as corn can benefit from new technological innovations, and that, conversely, technologies like mobile banking can aid those whose rural existence consists of low-tech market vending. In addition, technological advances in areas like mobile phones can lead to competition, lowered prices, and concurrent improvements in related areas such as mobile banking and information sharing. However, the same patterns of social inequality that create a digital divide in the United States also create digital divides in peripheral and semi-peripheral nations. While the growth of technology use among countries has increased dramatically over the past several decades, the spread of technology within countries is significantly slower among peripheral and semi-peripheral nations. In these countries, far fewer people have the training and skills to take advantage of new technology, let alone access it. Technological access tends to be clustered around urban areas, leaving out vast swaths of peripheral-nation citizens. While the diffusion of information technologies has the potential to resolve many global social problems, it is often the population most in need that is most affected by the digital divide. For example, technology to purify water could save many lives, but the villages in peripheral nations most in need of water purification don’t have access to the technology, the funds to purchase it, or the technological comfort level to introduce it as a solution. Sociology in the Real World The Mighty Cell Phone: How Mobile Phones Are Impacting Sub-Saharan Africa In much of Africa’s poorest countries there is a marked lack of infrastructure. Bad roads, limited electricity, minimal schools—the list goes on. Access to telephones has long been on that list. But while landline access has not changed appreciably during the past 10 years, there’s been a marked fivefold increase in mobile phone access; more than a third of people in Sub-Saharan Africa have the ability to access a mobile phone (Katine 2010). Even more can access a “village phone”—a shared phone program created by the Grameen Foundation. With access to mobile phone technology, a host of benefits are available that have the potential to change the dynamics in these poorest nations. Sometimes that change is as simple as being able to make a phone call to neighboring market towns. By finding out which markets have vendors interested in their goods, fishers and farmers can ensure they travel to the market that will serve them best, avoiding a wasted trip. Others can use mobile phones and some of the emerging money-sending systems to securely send money from one place to a family member or business partner elsewhere (Katine 2010). These programs are often funded by businesses like Germany’s Vodafone or Britain’s Masbabi, which hope to gain market share in the region. Phone giant Nokia points out that worldwide there are 4 billion mobile phone users—that’s more than twice as many bank accounts that exist—meaning there is ripe opportunity to connect banking companies with people who need their services (ITU Telecom 2009). Not all access is corporate-based, however. Other programs are funded by business organizations that seek to help peripheral nations with tools for innovation and entrepreneurship. But this wave of innovation and potential business comes with costs. There is, certainly, the risk of cultural imperialism, and the assumption that core nations (and core-nation multinationals) know what is best for those struggling in the world’s poorest communities. Whether well intentioned or not, the vision of a continent of Africans successfully chatting on their iPhone may not be ideal. As with all aspects of global inequity, technology in Africa requires more than just foreign investment. There must be a concerted effort to ensure the benefits of technology get to where they are needed most. 8.4 Theoretical Perspectives on Media and Technology It is difficult to conceive of any one theory or theoretical perspective that can explain the variety of ways that people interact with technology and the media. Technology runs the gamut from the match you strike to light a candle all the way up to sophisticated nuclear power plants that might power the factory where that candle, was made. Media could refer to the television you watch, the ads wrapping the bus you take to work or school, or the magazines you flip through in a waiting room, not to mention all the forms of new media, including Twitter, Facebook, blogs, YouTube, and the like. Are media and technology critical to the forward march of humanity? Are they pernicious capitalist tools that lead to the exploitation of workers worldwide? Are they the magic bullet the world has been waiting for to level the playing field and raise the world’s poor out of extreme poverty? Choose any opinion and you will find studies and scholars that agree with you––and those who disagree. Functionalism Because functionalism focuses on how media and technology contribute to the smooth functioning of society, a good place to begin understanding this perspective is to write a list of functions you perceive media and technology to perform. Your list might include the ability to find information on the internet, television’s entertainment value, or how advertising and product placement contribute to social norms. Commercial Function As you might guess, with nearly every U.S. household possessing a television, and the 250 billion hours of television watched annually by Americans, companies that wish to connect with consumers find television an irresistible platform to promote their goods and services (Nielsen 2012). Television advertising is a highly functional way to meet a market demographic where it lives. Sponsors can use the sophisticated data gathered by network and cable television companies regarding their viewers and target their advertising accordingly. Whether you are watching cartoons on Nick Jr. or a cooking show on Telemundo, chances are advertisers have a plan to reach you. And it certainly doesn’t stop with television. Commercial advertising precedes movies in theaters and shows up on and inside of public transportation, as well as on the sides of building and roadways. Major corporations such as Coca-Cola bring their advertising into public schools, sponsoring sports fields or tournaments, as well as filling the halls and cafeterias of those schools with vending machines hawking their goods. With the rising concerns about childhood obesity and attendant diseases, the era of soda machines in schools may be numbered. But not to worry. Coca-Cola’s filtered tap water, Dasani, and its juice products will remain standards in many schools. Entertainment Function An obvious manifest function of media is its entertainment value. Most people, when asked why they watch television or go to the movies, would answer that they enjoy it. And the numbers certainly illustrate that. While 2012 Nielsen research shows a slight reduction of U.S. homes with televisions, the reach of television is still vast. And the amount of time spent watching is equally large. Clearly, enjoyment is paramount. On the technology side, as well, there is a clear entertainment factor to the use of new innovations. From online gaming to chatting with friends on Facebook, technology offers new and more exciting ways for people to entertain themselves. Social Norm Functions Even while the media is selling us goods and entertaining us, it also serves to socialize us, helping us pass along norms, values, and beliefs to the next generation. In fact, we are socialized and resocialized by media throughout our life course. All forms of media teach us what is good and desirable, how we should speak, how we should behave, and how we should react to events. Media also provide us with cultural touchstones during events of national significance. How many of your older relatives can recall watching the explosion of the space shuttle Challenger on television? How many of those reading this textbook followed the events of September 11 or Hurricane Katrina on the television or internet? But debate exists over the extent and impact of media socialization. One recent study (Krahe et al. 2011) demonstrated that violent media content does have a desensitizing affect and is correlated with aggressive thoughts. Another group of scholars (Gentile, Mathieson, and Crick 2011) found that among children exposure to media violence led to an increase in both physical and relational aggression. Yet, a meta-analysis study covering four decades of research (Savage 2003) could not establish a definitive link between viewing violence and committing criminal violence. It is clear from watching people emulate the styles of dress and talk that appear in media that media has a socializing influence. What is not clear, despite nearly 50 years of empirical research, is how much socializing influence the media has when compared to other agents of socialization, which include any social institution that passes along norms, values, and beliefs (such as peers, family, religious institutions, and the like). Life-Changing Functions Like media, many forms of technology do indeed entertain us, provide a venue for commercialization, and socialize us. For example, some studies suggest the rising obesity rate is correlated with the decrease in physical activity caused by an increase in use of some forms of technology, a latent function of the prevalence of media in society (Kautiainen et al. 2011). Without a doubt, a manifest function of technology is to change our lives, sometimes for the better and sometimes for the worse. Think of how the digital age has improved the ways we communicate. Have you ever used Skype or another webcast to talk to a friend or family member far away? Or maybe you have organized a fund drive, raising thousands of dollars, all from your desk chair. Of course, the downside to this ongoing information flow is the near impossibility of disconnecting from technology, leading to an expectation of constant convenient access to information and people. Such a fast-paced dynamic is not always to our benefit. Some sociologists assert that this level of media exposure leads to narcotizing dysfunction , a term that describes when people are too overwhelmed with media input to really care about the issue, so their involvement becomes defined by awareness instead of by action about the issue at hand (Lazerfeld and Merton 1948). Conflict Perspective In contrast to theories in the functional perspective, the conflict perspective focuses on the creation and reproduction of inequality—social processes that tend to disrupt society rather than contribute to its smooth operation. When taking a conflict perspective, one major focus is the differential access to media and technology embodied in the digital divide. Conflict theorists also look at who controls the media, and how media promotes the norms of upper-middle-class white Americans while minimizing the presence of the lower class, especially people of color. Control of Media and Technology Powerful individuals and social institutions have a great deal of influence over which forms of technology are released, when and where they are released, and what kind of media is available for our consumption, a form of gatekeeping. Shoemaker and Voss (2009) define gatekeeping as the sorting process by which thousands of possible messages are shaped into a mass media-appropriate form and reduced to a manageable amount. In other words, the people in charge of the media decide what the public is exposed to, which, as C. Wright Mills (1956) famously noted, is the heart of media’s power. Take a moment to think of the way that “new media” evolves and replaces traditional forms of hegemonic media. With a hegemonic media, culturally diverse society can be dominated by one race, gender, or class through the manipulation of the media imposing its worldview as a societal norm. New media renders the gatekeeper role less of a factor in information distribution. Popular sites such as YouTube and Facebook engage in a form of self-policing. Users are encouraged to report inappropriate behavior that moderators will then address. In addition, some conflict theorists suggest that the way American media is generated results in an unbalanced political arena. Those with the most money can buy the most media exposure, run smear campaigns against their competitors, and maximize their visual presence. Almost a year before the 2012 U.S. presidential election, the candidates––Barack Obama for the Democrats and numerous Republican contenders––have raised more than $186 million (Carmi et al. 2012). What do you think a conflict perspective theorist would suggest about the potential for the non-rich to be heard in politics? Technological Social Control and Digital Surveillance Social scientists take the idea of the surveillance society so seriously that there is an entire journal devoted to its study, Surveillance and Society . The panoptic surveillance envisioned by Jeremy Bentham and later analyzed by Michel Foucault (1975) is increasingly realized in the form of technology used to monitor our every move. This surveillance was imagined as a form of constant monitoring in which the observation posts are decentralized and the observed is never communicated with directly. Today, digital security cameras capture our movements, observers can track us through our cell phones, and police forces around the world use facial-recognition software. Feminist Perspective Take a look at popular television shows, advertising campaigns, and online game sites. In most, women are portrayed in a particular set of parameters and tend to have a uniform look that society recognizes as attractive. Most are thin, white or light-skinned, beautiful, and young. Why does this matter? Feminist perspective theorists believe it’s crucial in creating and reinforcing stereotypes. For example, Fox and Bailenson (2009) found that online female avatars (the characters you play in online games like World of Warcraft or Second Life) conforming to gender stereotypes enhances negative attitudes toward women, and Brasted (2010) found that media (advertising in particular) promotes gender stereotypes. The gender gap in tech-related fields (science, technology, engineering, and math) is no secret. A 2011 U.S. Department of Commerce Report suggested that gender stereotyping is one reason for this gap, acknowledging the bias toward men as keepers of technological knowledge (US Department of Commerce 2011). But gender stereotypes go far beyond the use of technology. Press coverage in the media reinforces stereotypes that subordinate women, giving airtime to looks over skills, and disparaging women who defy accepted norms. Recent research in new media has offered a mixed picture of its potential to equalize the status of men and women in the arenas of technology and public discourse. A European agency, the Advisory Committee on Equal Opportunities for Men and Women (2010), issued an opinion report suggesting that while there is the potential for new media forms to perpetuate gender stereotypes and the gender gap in technology and media access, at the same time new media could offer alternative forums for feminist groups and the exchange of feminist ideas. Still, the committee warned against the relatively unregulated environment of new media and the potential for antifeminist activities, from pornography to human trafficking, to flourish there. Increasingly prominent in the discussion of new media and feminism is cyberfeminism , the application to, and promotion of, feminism online. Research on cyberfeminism runs the gamut from the liberating use of blogs by women living in Iraq during the second Gulf War (Peirce 2011) to an investigation of the Suicide Girls web site (Magnet 2007). Symbolic Interactionism Technology itself may act as a symbol for many. The kind of computer you own, the kind of car you drive, whether or not you can afford the latest Apple product—these serve as a social indicator of wealth and status. Neo-Luddites are people who see technology as symbolizing the coldness and alienation of modern life. But for technophiles , technology symbolizes the potential for a brighter future. For those adopting an ideological middle ground, technology might symbolize status (in the form of a massive flat-screen television) or failure (in owning a basic old mobile phone with no bells or whistles). Social Construction of Reality Meanwhile, media create and spread symbols that become the basis for our shared understanding of society. Theorists working in the interactionist perspective focus on this social construction of reality, an ongoing process in which people subjectively create and understand reality. Media constructs our reality in a number of ways. For some, the people they watch on a screen can become a primary group, meaning the small informal groups of people who are closest to them. For many others, media becomes a reference group: a group that influences an individual and to which an individual compares himself, and by which we judge our successes and failures. We might do very well without an Android smartphone, until we see characters using it on our favorite television show or our classmates whipping one out between classes. While media may indeed be the medium to spread the message of the rich white males, Gamson, Croteau, Hoynes, and Sasson (1992) point out that some forms of media discourse allow the appearance of competing constructions of reality. For example, advertisers find new and creative ways to sell us products we don’t need and probably wouldn’t want without their prompting, but some networking sites such as Freecycle offer a commercial-free way of requesting and trading items that would otherwise be discarded. Additionally, the web is full of blogs chronicling lives lived “off the grid,” or without participation in the commercial economy. Social Networking and Social Construction While Twitter and Facebook encourage us to check in and provide details of our day through online social networks, corporations can just as easily promote their products on these sites. Even supposedly crowd-sourced sites like Yelp (which aggregates local reviews) are not immune to corporate shenanigans. That is, we think we are reading objective observations when in reality we may be buying into one more form of advertising. Facebook, which started as a free social network for college students, is increasingly a monetized business, selling you goods and services in subtle ways. But chances are you don’t think of Facebook as one big online advertisement. What started out as a symbol of coolness and insider status, unavailable and inaccessible to parents and corporate shills, now promotes consumerism in the form of games and fandom. For example, think of all the money spent to upgrade popular Facebook games like Farmville. And notice that whenever you become a “fan,” you likely receive product updates and special deals that promote online and real -world consumerism. It is unlikely that millions of people want to be “friends” with Pampers. But if it means a weekly coupon, they will, in essence, rent out space on their Facebook page for Pampers to appear. Thus, we develop both new ways to spend money and brand loyalties that will last even after Facebook is considered outdated and obsolete.
principles_of_accounting,_volume_2:_managerial_accounting
Summary 4.1 Distinguish between Job Order Costing and Process Costing Job order costing (JOC) is the optimal costing method for producing custom goods or when it is easy to identify the cost directly with the product. A JOC system assigns costs to each individual job as the costs are incurred, so that at all points in the manufacturing process, the costs assigned to that particular job are known. 4.2 Describe and Identify the Three Major Components of Product Costs under Job Order Costing Direct materials are requested on a materials requisition form and recorded on the job cost sheet when transferred from raw materials inventory to the work in process inventory. Time tickets are used to accumulate the labor associated with particular jobs and assigned to those jobs on the job cost sheet. Manufacturing overhead costs are accumulated in the manufacturing overhead account and assigned to the individual jobs using the predetermined overhead rate. 4.3 Use the Job Order Costing Method to Trace the Flow of Product Costs through the Inventory Accounts Materials used in production include the beginning raw materials inventory and purchases, less the ending inventory. This amount is the amount added to the work in process inventory. The cost of goods manufactured includes the beginning work in process inventory, the materials used in production, the direct labor assigned to each job, and the manufacturing overhead costs assigned, less the costs remaining in the work in process inventory. This amount is transferred to the finished goods inventory. The cost of goods sold include the beginning finished goods inventory and the cost of goods manufactured during the period, less the ending inventory. When the job is completed, the costs are transferred from the work in process inventory to the finished goods inventory. When the jobs are sold, the costs are transferred from the finished goods inventory to the cost of goods sold. 4.4 Compute a Predetermined Overhead Rate and Apply Overhead to Production Expenses are recognized when they have a direct relationship with the associated revenue, when there is a systematic and rational method to allocate them, or immediately when there is no expected benefit. The estimated activity base is typically direct labor dollars or direct labor hours, and is based on an allocation base that increases or decreases as overhead increases or decreases. The predetermined overhead rate is the estimated overhead divided by the activity base. 4.5 Compute the Cost of a Job Using Job Order Costing Costs from the materials requisition sheet and time tickets are recorded on the job cost sheet. Overhead is allocated from the manufacturing overhead account to the individual jobs and recorded on the job cost sheet. Each job has its own job cost sheet, showing the materials, labor, and overhead for each job. 4.6 Determine and Dispose of Underapplied or Overapplied Overhead Overhead is allocated to individual jobs based on the estimated overhead costs for the year and may be overapplied or underapplied for the year. Overhead is underapplied when not all of the costs accumulated in the manufacturing overhead account are applied during the year. Overhead is overapplied when more overhead is applied to the jobs than was actually incurred. The amount of overhead overapplied or underapplied is adjusted into the cost of goods sold account. 4.7 Prepare Journal Entries for a Job Order Cost System Job cost sheets record the material, labor, and overhead costs for each job, whereas journal entries actually transfer the costs into the work in process inventory, the finished goods inventory, and cost of goods sold. 4.8 Explain How a Job Order Cost System Applies to a Nonmanufacturing Environment Job order costing can be used in nonmanufacturing companies and with the same techniques, even though there are not any inventory accounts.
Chapter Outline 4.1 Distinguish between Job Order Costing and Process Costing 4.2 Describe and Identify the Three Major Components of Product Costs under Job Order Costing 4.3 Use the Job Order Costing Method to Trace the Flow of Product Costs through the Inventory Accounts 4.4 Compute a Predetermined Overhead Rate and Apply Overhead to Production 4.5 Compute the Cost of a Job Using Job Order Costing 4.6 Determine and Dispose of Underapplied or Overapplied Overhead 4.7 Prepare Journal Entries for a Job Order Cost System 4.8 Explain How a Job Order Cost System Applies to a Nonmanufacturing Environment Why It Matters Hallie graduated from college last year and moved to Tempe, Arizona, to begin her career. Before moving, she purchased a secondhand dresser for $35 and spent $25 on refinishing materials. After two hours of work, she posted a picture of the dresser on social media, and a friend offered her $100 to refinish another dresser exactly the same way. Fortunately, Hallie understands cost accounting and knew she needed to calculate the cost to refinish another dresser. She found a similar dresser for $65. She knows that the refinishing materials will cost $25, and thus before adding in any cost for labor she is already at a cost of $90, without considering any overhead, such as electricity to run her sander. Hallie estimated that her labor costs should be $20 per hour. The total cost then would be $130, and accepting less would mean accepting less for her labor. For a business in this situation, agreeing to the $100 offer would be considered a loss. If Hallie accepts the $100 price before checking her costs, she would have received only $10 for her labor (the sales price of $100 less the $90 cost of the dresser and materials). Hallie didn’t know if she would lose a potential customer by raising the price, so she found a different style dresser costing $25. A sales price of $100 would be fair with the two hours to refinish at $20 per hour and a materials cost of $25. She offered her friend the original style dresser for $130 or the alternate style dresser for $100. As this example illustrates, it was essential for Hallie to know the cost to complete her project. It is also essential for all types and sizes of organizations to know the costs to complete their project. Manufacturing organizations need to know the costs of production, retail organizations need to know the cost to sell their products, and service organizations need to know the cost of providing their services. Management strives to eliminate unnecessary costs and needs to know the costs associated with using large pieces of equipment as well as seemingly insignificant office supplies. Cost accounting involves measuring and reporting the cost of production or service, while also providing data to determine the cost of the individual unit produced.
[ { "answer": { "ans_choice": 1, "ans_text": "B" }, "bloom": null, "hl_context": "<hl> Both job order costing and process costing track the costs of materials , labor , and overhead as components of virtually all products . <hl> The process of production does not change because of the costing method : The costing method is chosen based on the process of production and is intended to provide the most accurate representation of the costs incurred in the production process .", "hl_sentences": "Both job order costing and process costing track the costs of materials , labor , and overhead as components of virtually all products .", "question": { "cloze_format": "The product situation that is better suited to job order costing than to process costing is that ___.", "normal_format": "Which of the following product situations is better suited to job order costing than to process costing?", "question_choices": [ "Each product batch is exactly the same as the prior batch.", "The costs are easily traced to a specific product.", "Costs are accumulated by department.", "The value of work in process is based on assigning standard costs." ], "question_id": "fs-idm228500032", "question_text": "Which of the following product situations is better suited to job order costing than to process costing?" }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 2, "ans_text": "an accounting firm specializing in tax returns" }, "bloom": null, "hl_context": "<hl> Since a typical tax return can vary significantly from one taxpayer to the next , H & R Block provides a service that they customize for each customer . <hl> <hl> Its cost data are collected via a job order cost system , which is designed to allow for individualized products or services . <hl>", "hl_sentences": "Since a typical tax return can vary significantly from one taxpayer to the next , H & R Block provides a service that they customize for each customer . Its cost data are collected via a job order cost system , which is designed to allow for individualized products or services .", "question": { "cloze_format": "A job order costing system is most likely used by ___ .", "normal_format": "A job order costing system is most likely used by which of the following?", "question_choices": [ "a pet food manufacturer", "a paper manufacturing company", "an accounting firm specializing in tax returns", "a stereo manufacturing company" ], "question_id": "fs-idm233047792", "question_text": "A job order costing system is most likely used by which of the following?" }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 1, "ans_text": "B" }, "bloom": null, "hl_context": "<hl> The assignment of direct materials and direct labor to each production unit illustrates the job order costing system ’ s focus on prime costs , in contrast to the process costing system , which assigns costs to the department and focuses on direct materials and conversion costs , which are composed of a combination of direct labor and overhead . <hl> Process costs will be demonstrated in Process Costing . In a manufacturing environment , the manufacturing costs are also called product costs and include all expenses used to manufacture the product : direct materials , direct labor , and manufacturing overhead . To review these costs , see Building Blocks of Managerial Accounting . The total of these costs becomes the cost of ending inventory and later becomes the cost of goods sold when the product is sold . Both job order costing and process costing use categorized cost information to make decisions and evaluate the effectiveness of the cost tracking process . Because of the difference in how each of the two costing systems track costs , different terminology is used . Thus , it is important to separate product costs from period costs , and it is sometimes important to separate product costs into prime costs and conversion costs . <hl> Prime costs are costs that include the primary ( or direct ) product costs : direct materials and direct labor . <hl> Conversion costs are costs that include the expenses necessary to convert direct materials into a finished product : direct labor and manufacturing overhead . Their relationship is shown in Figure 4.4 .", "hl_sentences": "The assignment of direct materials and direct labor to each production unit illustrates the job order costing system ’ s focus on prime costs , in contrast to the process costing system , which assigns costs to the department and focuses on direct materials and conversion costs , which are composed of a combination of direct labor and overhead . Prime costs are costs that include the primary ( or direct ) product costs : direct materials and direct labor .", "question": { "cloze_format": "___ is a prime cost.", "normal_format": "Which of the following is a prime cost?", "question_choices": [ "indirect materials", "direct labor", "administrative expenses", "factory depreciation expenses" ], "question_id": "fs-idm218932160", "question_text": "Which of the following is a prime cost?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 3, "ans_text": "factory depreciation expenses" }, "bloom": null, "hl_context": "The estimated or budgeted overhead is the amount of overhead determined during the budgeting process and consists of manufacturing costs but , as you have learned , excludes direct materials and direct labor . <hl> Examples of manufacturing overhead costs include indirect materials , indirect labor , manufacturing utilities , and manufacturing equipment depreciation . <hl> Another way to view it is overhead costs are those production costs that are not categorized as direct materials or direct labor . In a manufacturing environment , the manufacturing costs are also called product costs and include all expenses used to manufacture the product : direct materials , direct labor , and manufacturing overhead . To review these costs , see Building Blocks of Managerial Accounting . The total of these costs becomes the cost of ending inventory and later becomes the cost of goods sold when the product is sold . Both job order costing and process costing use categorized cost information to make decisions and evaluate the effectiveness of the cost tracking process . Because of the difference in how each of the two costing systems track costs , different terminology is used . Thus , it is important to separate product costs from period costs , and it is sometimes important to separate product costs into prime costs and conversion costs . Prime costs are costs that include the primary ( or direct ) product costs : direct materials and direct labor . <hl> Conversion costs are costs that include the expenses necessary to convert direct materials into a finished product : direct labor and manufacturing overhead . <hl> Their relationship is shown in Figure 4.4 .", "hl_sentences": "Examples of manufacturing overhead costs include indirect materials , indirect labor , manufacturing utilities , and manufacturing equipment depreciation . Conversion costs are costs that include the expenses necessary to convert direct materials into a finished product : direct labor and manufacturing overhead .", "question": { "cloze_format": "___ are a conversion cost.", "normal_format": "Which of the following is a conversion cost?", "question_choices": [ "raw materials", "direct materials", "administrative expenses", "factory depreciation expenses" ], "question_id": "fs-idm250503728", "question_text": "Which of the following is a conversion cost?" }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 2, "ans_text": "C" }, "bloom": null, "hl_context": "To summarize the job order cost system , the cost of each job includes direct materials , direct labor , and manufacturing overhead . While the product is in production , the direct materials and direct labor costs are included in the work in process inventory . The direct materials are requested by the production department , and the direct material cost is directly attached to each individual job , as the materials are released from raw materials inventory . <hl> The cost of direct labor is recorded by the employees and assigned to each individual job . <hl> When the allocation base is known , usually when the product is completed , the overhead is allocated to the product on the basis of the predetermined overhead rate . Since a typical tax return can vary significantly from one taxpayer to the next , H & R Block provides a service that they customize for each customer . <hl> Its cost data are collected via a job order cost system , which is designed to allow for individualized products or services . <hl>", "hl_sentences": "The cost of direct labor is recorded by the employees and assigned to each individual job . Its cost data are collected via a job order cost system , which is designed to allow for individualized products or services .", "question": { "cloze_format": "During production, the costs in job order costing are applied to ___.", "normal_format": "During production, to what are the costs in job order costing applied?", "question_choices": [ "manufacturing overhead", "cost of goods sold", "each individual product", "each individual department" ], "question_id": "fs-idm242695728", "question_text": "During production, to what are the costs in job order costing applied?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 2, "ans_text": "materials requisition form" }, "bloom": null, "hl_context": "<hl> Within the raw materials inventory account , purchases increase the inventory , whereas raw materials sent into production reduce it . <hl> <hl> It is easy to reconcile the amount of ending inventory and the cost of direct materials used in production , since the materials requisition form ( Figure 4.7 ) keeps track of the inventory requested and sent into each specific job . <hl> Since the costs are transferred with production , the calculation shows the amount of materials used in production : Returning to the example of Dinosaur Vinyl ’ s order for Macs & Cheese ’ s stadium sign , Figure 4.7 shows the materials requisition form for Job MAC 001 . This form indicates the quantity and specific items to be put into the work in process . <hl> It also transfers the cost of those items to the work in process inventory and decreases the raw materials inventory by the same amount . <hl> The raw materials inventory department maintains a copy to document the change in inventory levels , and the accounting department maintains a copy to properly assign the costs to the particular job .", "hl_sentences": "Within the raw materials inventory account , purchases increase the inventory , whereas raw materials sent into production reduce it . It is easy to reconcile the amount of ending inventory and the cost of direct materials used in production , since the materials requisition form ( Figure 4.7 ) keeps track of the inventory requested and sent into each specific job . It also transfers the cost of those items to the work in process inventory and decreases the raw materials inventory by the same amount .", "question": { "cloze_format": "The document that lists the inventory that will be removed from the raw materials inventory is the ___ .", "normal_format": "Which document lists the inventory that will be removed from the raw materials inventory?", "question_choices": [ "job cost sheet", "purchase order", "materials requisition form", "receiving document" ], "question_id": "fs-idm240915040", "question_text": "Which document lists the inventory that will be removed from the raw materials inventory?" }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 0, "ans_text": "A" }, "bloom": null, "hl_context": "<hl> At all points in the process , the work in process should include the cost of direct materials and direct labor . <hl> <hl> When the job is completed and overhead assigned , the overhead allocation increases the cost of the work in process inventory . <hl> <hl> The cost of each individual job is maintained on a job cost sheet , and the total of all the work in process job cost sheets equals the work in process inventory and the statement of cost of goods manufactured , as you have learned . <hl> <hl> Job order cost systems maintain the actual direct materials and direct labor for each individual job . <hl> <hl> Since production consists of overhead — indirect materials , indirect labor , and other overhead — we need a methodology for applying that overhead . <hl> Unfortunately , the nature of indirect material , indirect labor , and other overhead expenses makes it impossible to determine the exact amount of overhead for each specific job . For example , how do you know the cost of electricity and heat for manufacturing one job ? And , if you did , is it fair to say products manufactured in January are more expensive than the same product manufactured in March because of heat expense ?", "hl_sentences": "At all points in the process , the work in process should include the cost of direct materials and direct labor . When the job is completed and overhead assigned , the overhead allocation increases the cost of the work in process inventory . The cost of each individual job is maintained on a job cost sheet , and the total of all the work in process job cost sheets equals the work in process inventory and the statement of cost of goods manufactured , as you have learned . Job order cost systems maintain the actual direct materials and direct labor for each individual job . Since production consists of overhead — indirect materials , indirect labor , and other overhead — we need a methodology for applying that overhead .", "question": { "cloze_format": "The document that shows the cost of direct materials, direct labor, and overhead applied for each specific job is a ___.", "normal_format": "Which document shows the cost of direct materials, direct labor, and overhead applied for each specific job?", "question_choices": [ "job cost sheet", "purchase order", "materials requisition form", "receiving document" ], "question_id": "fs-idm264795440", "question_text": "Which document shows the cost of direct materials, direct labor, and overhead applied for each specific job?" }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 2, "ans_text": "materials requisition form" }, "bloom": null, "hl_context": "Within the raw materials inventory account , purchases increase the inventory , whereas raw materials sent into production reduce it . <hl> It is easy to reconcile the amount of ending inventory and the cost of direct materials used in production , since the materials requisition form ( Figure 4.7 ) keeps track of the inventory requested and sent into each specific job . <hl> Since the costs are transferred with production , the calculation shows the amount of materials used in production :", "hl_sentences": "It is easy to reconcile the amount of ending inventory and the cost of direct materials used in production , since the materials requisition form ( Figure 4.7 ) keeps track of the inventory requested and sent into each specific job .", "question": { "cloze_format": "The document that lists the total direct materials used in a specific job is the ___ .", "normal_format": "Which document lists the total direct materials used in a specific job?", "question_choices": [ "job cost sheet", "purchase order", "materials requisition form", "receiving document" ], "question_id": "fs-idm243800992", "question_text": "Which document lists the total direct materials used in a specific job?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 0, "ans_text": "A" }, "bloom": null, "hl_context": "At all points in the process , the work in process should include the cost of direct materials and direct labor . When the job is completed and overhead assigned , the overhead allocation increases the cost of the work in process inventory . <hl> The cost of each individual job is maintained on a job cost sheet , and the total of all the work in process job cost sheets equals the work in process inventory and the statement of cost of goods manufactured , as you have learned . <hl>", "hl_sentences": "The cost of each individual job is maintained on a job cost sheet , and the total of all the work in process job cost sheets equals the work in process inventory and the statement of cost of goods manufactured , as you have learned .", "question": { "cloze_format": "The ___ is a document that lists the total direct labor used in a specific job.", "normal_format": "Which document lists the total direct labor used in a specific job?", "question_choices": [ "job cost sheet", "purchase order", "employee time ticket", "receiving document" ], "question_id": "fs-idm245826288", "question_text": "Which document lists the total direct labor used in a specific job?" }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 1, "ans_text": "using the predetermined overhead rate" }, "bloom": null, "hl_context": "The expense recognition principle also applies to manufacturing overhead costs . <hl> The manufacturing overhead is an expense of production , even though the company is unable to trace the costs directly to each specific job . <hl> For example , the electricity needed to run production equipment typically is not easily traced to a particular product or job , yet it is still a cost of production . As a cost of production , the electricity — one type of manufacturing overhead — becomes a cost of the product and part of inventory costs until the product or job is sold . <hl> Fortunately , the accounting system keeps track of the manufacturing overhead , which is then applied to each individual job in the overhead allocation process . <hl> <hl> Material and labor costs that cannot be traced directly to the product produced are included in the overhead costs that are allocated in the production costing process . <hl> <hl> Overhead is applied to each product based on an activity base , which will be explained in Compute a Predetermined Overhead Rate and Apply Overhead to Production . <hl>", "hl_sentences": "The manufacturing overhead is an expense of production , even though the company is unable to trace the costs directly to each specific job . Fortunately , the accounting system keeps track of the manufacturing overhead , which is then applied to each individual job in the overhead allocation process . Material and labor costs that cannot be traced directly to the product produced are included in the overhead costs that are allocated in the production costing process . Overhead is applied to each product based on an activity base , which will be explained in Compute a Predetermined Overhead Rate and Apply Overhead to Production .", "question": { "cloze_format": "Assigning indirect costs to specific jobs is completed by ___.", "normal_format": "Assigning indirect costs to specific jobs is completed by which of the following?", "question_choices": [ "applying the costs to manufacturing overhead", "using the predetermined overhead rate", "using the manufacturing costs incurred", "applying the indirect labor to the work in process inventory" ], "question_id": "fs-idm223681184", "question_text": "Assigning indirect costs to specific jobs is completed by which of the following?" }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 3, "ans_text": "D" }, "bloom": null, "hl_context": "Maintaining accounting records for each system has its advantages . <hl> A job order costing system uses a job cost sheet to keep track of individual jobs and the direct materials , direct labor , and overhead associated with each job . <hl> The focus of a job order costing system is tracking costs per job , since each job is unique and therefore has different costs relative to other jobs . Maintaining this information is typically more expensive than process costing , and it is often used for the production of smaller , more individualized jobs because the benefit of knowing the cost of each product outweighs the additional cost of maintaining a job order costing system .", "hl_sentences": "A job order costing system uses a job cost sheet to keep track of individual jobs and the direct materials , direct labor , and overhead associated with each job .", "question": { "cloze_format": "In a job order cost system, the account that shows the overhead used by the company is the ___.", "normal_format": "In a job order cost system, which account shows the overhead used by the company?", "question_choices": [ "work in process inventory", "finished goods inventory", "cost of goods sold", "manufacturing overhead" ], "question_id": "fs-idm238066736", "question_text": "In a job order cost system, which account shows the overhead used by the company?" }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 0, "ans_text": "raw materials inventory" }, "bloom": null, "hl_context": "While the flow of costs is generally the same for all costing systems , the difference is in the details : Product costs have material , labor , and overhead costs , which may be assessed differently . <hl> In most production facilities , the raw materials are moved from the raw materials inventory into the work in process inventory . <hl> The work in process involves one or more production departments and is where labor and overhead convert the raw materials into finished goods . The movement of these costs through the work in process inventory is shown in Figure 4.5 .", "hl_sentences": "In most production facilities , the raw materials are moved from the raw materials inventory into the work in process inventory .", "question": { "cloze_format": "In a job order cost system, the account to which raw materials purchased are debited is called the ___ .", "normal_format": "In a job order cost system, raw materials purchased are debited to which account?", "question_choices": [ "raw materials inventory", "work in process inventory", "finished goods inventory", "cost of goods sold" ], "question_id": "fs-idm225356304", "question_text": "In a job order cost system, raw materials purchased are debited to which account?" }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 0, "ans_text": "A" }, "bloom": null, "hl_context": "<hl> Over the fiscal year , the actual costs are recorded as debits into the account called manufacturing overhead . <hl> When the overhead is applied to the jobs , the amount is first calculated using the application rate . If the total labor paid for the job is $ 66 , the overhead applied to the job is $ 2.50 times that amount , or $ 165 . The entry to record the overhead for Job MAC 001 is : <hl> While the flow of costs is generally the same for all costing systems , the difference is in the details : Product costs have material , labor , and overhead costs , which may be assessed differently . <hl> <hl> In most production facilities , the raw materials are moved from the raw materials inventory into the work in process inventory . <hl> The work in process involves one or more production departments and is where labor and overhead convert the raw materials into finished goods . The movement of these costs through the work in process inventory is shown in Figure 4.5 .", "hl_sentences": "Over the fiscal year , the actual costs are recorded as debits into the account called manufacturing overhead . While the flow of costs is generally the same for all costing systems , the difference is in the details : Product costs have material , labor , and overhead costs , which may be assessed differently . In most production facilities , the raw materials are moved from the raw materials inventory into the work in process inventory .", "question": { "cloze_format": "In a job order cost system, overhead applied is debited to the ___.", "normal_format": "In a job order cost system, overhead applied is debited to which account?", "question_choices": [ "work in process inventory", "finished goods inventory", "manufacturing overhead", "cost of goods sold" ], "question_id": "fs-idm232500384", "question_text": "In a job order cost system, overhead applied is debited to which account?" }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 1, "ans_text": "work in process inventory" }, "bloom": null, "hl_context": "<hl> Job order costing systems assign costs directly to the product by assigning direct materials and direct labor to the work in process ( WIP ) inventory . <hl> As you learned in Building Blocks of Managerial Accounting , direct materials are the components that can be directly traced to the products produced , whereas direct labor is the labor cost that can be directly traced to the products produced .", "hl_sentences": "Job order costing systems assign costs directly to the product by assigning direct materials and direct labor to the work in process ( WIP ) inventory .", "question": { "cloze_format": "In a job order cost system, factory wage expense is debited to ___.", "normal_format": "In a job order cost system, factory wage expense is debited to which account?", "question_choices": [ "raw materials inventory", "work in process inventory", "finished goods inventory", "cost of goods sold" ], "question_id": "fs-idm248866480", "question_text": "In a job order cost system, factory wage expense is debited to which account?" }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 2, "ans_text": "C" }, "bloom": null, "hl_context": "<hl> Over the fiscal year , the actual costs are recorded as debits into the account called manufacturing overhead . <hl> When the overhead is applied to the jobs , the amount is first calculated using the application rate . If the total labor paid for the job is $ 66 , the overhead applied to the job is $ 2.50 times that amount , or $ 165 . The entry to record the overhead for Job MAC 001 is : <hl> Traditionally , direct labor hours were used as the activity base , but technology continually decreases the amount of direct labor used in production , and machine hours or units produced have become more common activity bases . <hl> <hl> Management analyzes the costs and selects the activity as the estimated activity base because it drives the overhead costs of the unit . <hl>", "hl_sentences": "Over the fiscal year , the actual costs are recorded as debits into the account called manufacturing overhead . Traditionally , direct labor hours were used as the activity base , but technology continually decreases the amount of direct labor used in production , and machine hours or units produced have become more common activity bases . Management analyzes the costs and selects the activity as the estimated activity base because it drives the overhead costs of the unit .", "question": { "cloze_format": "In a job order cost system, utility expense incurred is debited to ___.", "normal_format": "In a job order cost system, utility expense incurred is debited to which account?", "question_choices": [ "work in process inventory", "finished goods inventory", "manufacturing overhead", "cost of goods sold" ], "question_id": "fs-idm227411808", "question_text": "In a job order cost system, utility expense incurred is debited to which account?" }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 2, "ans_text": "manufacturing overhead" }, "bloom": null, "hl_context": "Indirect labor records are also maintained through time tickets , although such work is not directly traceable to a specific job . <hl> The difference between direct labor and indirect labor is that the indirect labor records the debit to manufacturing overhead while the credit is to factory wages payable . <hl> Job order cost systems maintain the actual direct materials and direct labor for each individual job . <hl> Since production consists of overhead — indirect materials , indirect labor , and other overhead — we need a methodology for applying that overhead . <hl> Unfortunately , the nature of indirect material , indirect labor , and other overhead expenses makes it impossible to determine the exact amount of overhead for each specific job . For example , how do you know the cost of electricity and heat for manufacturing one job ? And , if you did , is it fair to say products manufactured in January are more expensive than the same product manufactured in March because of heat expense ?", "hl_sentences": "The difference between direct labor and indirect labor is that the indirect labor records the debit to manufacturing overhead while the credit is to factory wages payable . Since production consists of overhead — indirect materials , indirect labor , and other overhead — we need a methodology for applying that overhead .", "question": { "cloze_format": "In a job order cost system, indirect labor incurred is debited to ___.", "normal_format": "In a job order cost system, indirect labor incurred is debited to which account?", "question_choices": [ "work in process inventory", "finished goods inventory", "manufacturing overhead", "cost of goods sold" ], "question_id": "fs-idm218267296", "question_text": "In a job order cost system, indirect labor incurred is debited to which account?" }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 3, "ans_text": "D" }, "bloom": null, "hl_context": "Instead of being dependent on materials , service industries depend on labor . <hl> Since their work is labor intensive , it makes sense to use labor as an activity base with billable hours often as the best allocation base . <hl> For example , in an audit , there often will be several accountants , with differing levels of experience and expertise involved in the assignment . The accounting firms have more billable hours at the staff level and fewer billable hours at the partner level . And since the firm bills the partner ’ s time at a significantly higher rate than the staff , it makes sense to apply overhead at the billable hours instead of the billable costs . <hl> Traditionally , direct labor hours were used as the activity base , but technology continually decreases the amount of direct labor used in production , and machine hours or units produced have become more common activity bases . <hl> Management analyzes the costs and selects the activity as the estimated activity base because it drives the overhead costs of the unit .", "hl_sentences": "Since their work is labor intensive , it makes sense to use labor as an activity base with billable hours often as the best allocation base . Traditionally , direct labor hours were used as the activity base , but technology continually decreases the amount of direct labor used in production , and machine hours or units produced have become more common activity bases .", "question": { "cloze_format": "The activity base for service industries is most likely to be ________.", "normal_format": "What is the activity base for service industries most likely to be?", "question_choices": [ "machine hours", "administrative salaries", "direct labor cost", "direct labor hours" ], "question_id": "fs-idm229007872", "question_text": "The activity base for service industries is most likely to be ________." }, "references_are_paraphrase": null } ]
4
4.1 Distinguish between Job Order Costing and Process Costing Pet Smart , H&R Block , Chili’s , and Marshalls are popular chains often found at the same shopping center, even though they are very different businesses. Although they have a retail store, the Pet Smart Corporation also manufactures large volumes of its own products, whereas H&R Block prepares taxes for individual customers. Chili’s prepares food, and its wait staff provides a service, whereas Marshalls sells a variety of products at retail. The management of each business relies on knowing each cost when making decisions, such as setting the sales price, planning production and staffing schedules, and ordering materials. Although these companies share a common location, which suggests similar rental costs, all the other costs vary significantly. Because of these cost differences, each company must have a system for gathering its cost data. For example, Pet Smart manufactures Great Choice squeaker balls in large batches and collects cost data through a process costing system. A process costing system is often used to trace and determine production costs when similar products or services are provided. The concept and mechanics of a process costing system are addressed in Process Costing . Since a typical tax return can vary significantly from one taxpayer to the next, H&R Block provides a service that they customize for each customer. Its cost data are collected via a job order cost system, which is designed to allow for individualized products or services. Marshalls does not produce a product yet still needs a system to assign overhead costs to the products it sells. (Overhead was addressed in Building Blocks of Managerial Accounting .) And while Chili’s has the same nationwide menu, it needs a system to collect the costs for each menu item within each location. While companies may choose different cost accounting systems, each system must be capable of accumulating the costs incurred and allocating the costs to the product. Each costing system also requires the ability to obtain and analyze the cost data, and the more detailed the information needed, the higher the cost of collecting the data. The choice of cost accumulation system depends on the variety and type of products or services sold, or the type of manufacturing processes employed. The system used should be determined by weighing the cost of collecting the data and the benefit of having that information. Companies use different costing systems for determining the cost of custom products than they do for determining the cost of mass-produced products. When products are custom ordered, knowing the cost of the materials, labor, and overhead is critical to determining the sales price. As an easy example, think of a tailor who alters, repairs, and makes custom clothes for customers. If a customer orders a custom-made suit, the specific fabric, detail of any special features, and the time involved in sewing are all factors that will determine the total cost and, therefore, the selling price of the garment. Each component of the cost of producing the clothing will be tracked as it occurs, thus improving the accuracy of determining the price. However, in mass production, wherein one batch leads to a second batch, stopping the process to properly identify the materials, labor, and overhead costs used for each batch does not provide enough valuable data to justify determining the individual costing of each product. For example, in the case of a mass-produced clothing item, such as jeans, a company like Levi’s will track costs for a batch of jeans rather than for a pair of jeans. Levi’s had over $4.9 billion in revenue in 2017 generated from the many different styles and brands of clothing items they produce and sell. It would be difficult, and not cost effective, to track the cost of each individual clothing item; rather, it is more efficient to track the costs in each phase of the clothing-making process. Levi’s can then accumulate the costs of the phases of production to determine the total cost of production for a batch and allocate those costs over the number of pairs of jeans made. This process allows them to determine the cost of each item. Even retail companies need to know the cost of the purchased products before the sales price is set. While it seems simple to think of the sales price as the purchase price plus a markup, determining the markup costs needs to be an accurate process in order to ensure the sale price is higher than the product cost. To properly capture the information necessary for decision-making, there are different costing systems that track costs in order to determine sales prices, and to measure profits and manufacturing efficiency. As previously mentioned, the two traditional types of costing systems are job order costing and process costing. Each anticipates or determines unit costs of products being manufactured and/or services being provided prior to year-end. Companies may decide to use only one or a combination of methods. This chapter examines job order costing and demonstrates how it differs from process costing. Process Costing and other costing systems ( Activity-Based, Variable, and Absorption Costing ) are covered in other chapters. In this chapter, you will also learn the terminology used to track costs within the job order cost system and how to segregate and aggregate these costs to determine the costs of production in a job order costing environment. You will also learn how to record these job costs and where they appear on financial statements. Job Order Costing versus Process Costing Job order costing is an accounting system that traces the individual costs directly to a final job or service, instead of to the production department. It is used when goods are made to order or when individual costs are easy to trace to individual jobs, assuming that the additional information provides value. In these circumstances, the individual costs are easy to trace to the individual jobs. For example, assume that a homeowner wants to have a custom deck added to her home. Also assume that in order to fit her lot’s topography and her anticipated uses for the addition, she needs a uniquely designed deck. Her contractor will design the deck, price the necessary components (in this case, the direct materials, direct labor, and overhead), and construct it. The final cost will be unique to this project. If another homeowner wanted the contractor to construct a deck, the contractor would go through the same design and pricing process, and you would expect that the design and costs would not be the same as those of the deck in the first example, since the decks would differ from one another. The job order costing method also works well for companies such as movie production companies, print service providers, advertising agencies, building contractors, accounting firms, consulting entities, and repair service providers. For example, Star Wars: The Last Jedi is believed to have cost $200 million to produce, whereas Logan only cost $97 million. The production processes for both films differed significantly, so that the accumulated costs for each job also differed significantly. Both were made in 2017. 1 1 “Production Costs and Global Box Office Revenue of Star Wars Movies from 1977 to 2018 (in million U.S. dollars).” The Statistics Portal. https://www.statista.com/statistics/311356/star-wars-production-costs-box-office-revenue/. In contrast, process costing is used when the manufacturing process is continuous, so it is difficult to establish how much of each material is used and exactly how much time is invested in each unit of finished product. Therefore, in process costing, costs are accounted for by the production process or production department instead of by the product or by the job. This method works well for manufacturers of products such as Titleist golf balls, Kellogg’s cereal, Turkey Hill ice cream, CITGO gasoline, Dow Chemicals, or Sherwin Williams ’ paints. However, process costing is not limited to basic manufacturing activities: It can also be used in the manufacturing of more complex items, such as small engines. A process costing system assigns costs to each department as the costs are incurred, and the costs to produce one unit are calculated based on the information from the production department. Unit costs are determined after total production costs are determined. One factor that can complicate the choice between job order costing and process costing is the growth of automation in the production process, which typically is accompanied by a reduction in direct labor. The cost of the increase in equipment (typically reflected as a depreciation expense) is allocated to overhead, while the decreased need for labor usually reduces the direct labor cost. Because of these issues, some companies choose a hybrid system, using process costing to account for mass producing a part and using job order costing to account for assembling some of those individual parts into a custom product. Table 4.1 summarizes the use of these two systems. Job Order and Process Cost Systems   Job Order Cost System Process Cost System Product type Custom order Mass production Examples Signs, buildings, tax returns Folding tables, toys, buffet restaurants Cost accumulation Job lot Accumulated per process Work in process inventory Individual job cost sheets Separate work in process inventory department Record keeping Individual job cost sheets Production cost report Table 4.1 This table shows some of the differences between job order costing and process costing . To illustrate how a company can determine whether to use job order costing or process costing, consider the cost accounting options for a local restaurant. Macs & Cheese makes specialty macaroni and cheese, and the company wants to erect a special sign on an already constructed billboard outside a stadium. It wants to use this space to target stadium customers; thus, the company wants a sign built specifically for that site. Dinosaur Vinyl is secured as the sign manufacturer and would use job order costing to account for the associated manufacturing costs because of the unique nature of the sign, including the art work involved. However, if Macs & Cheese was designing a costing system for the specialty food product they market, they typically would use a process costing approach because their product is made and marketed in homogeneous, similar batches. Link to Learning Both job order and process costing are used to track costs with a goal of improved cost measurement efficiency. Bar codes can help with either type of costing. Verified Label, Print & Promotions, Inc. provides a list of how barcodes contribute to efficiency in cost tracking for more information. Organization of Flow of Goods through Production Regardless of the costing method used (job order costing, process costing, or another method), manufacturing companies are generally similar in their organizational structure and have a similar flow of goods through production . The diagram in Figure 4.2 shows a partial organizational chart for sign manufacturer Dinosaur Vinyl. The CEO has several direct reporting units—Financing, Production, Information Technology, Marketing, Human Resources, and Maintenance—each with a director responsible for several departments. The diagram also shows the departments that report to the production unit director and gives an indication as to the flow of goods through production. The flow of goods through production is more evident in Figure 4.3 , which depicts Dinosaur Vinyl as a simple factory with three stages of production. Raw materials are stored in the materials storeroom and delivered to the appropriate production department—cutting, painting, or assembly/finishing. The design department uses direct labor to create the design specifications, and, when completed, it sends them to the production department. The production department uses the material and design specifications and adds additional labor to create the sign. The sign is transferred to the finishing department for final materials and labor, before the sign is installed or delivered to the customer. Manufacturing Costs In a manufacturing environment, the manufacturing costs are also called product costs and include all expenses used to manufacture the product: direct materials, direct labor, and manufacturing overhead. To review these costs, see Building Blocks of Managerial Accounting . The total of these costs becomes the cost of ending inventory and later becomes the cost of goods sold when the product is sold. Both job order costing and process costing use categorized cost information to make decisions and evaluate the effectiveness of the cost tracking process. Because of the difference in how each of the two costing systems track costs, different terminology is used. Thus, it is important to separate product costs from period costs, and it is sometimes important to separate product costs into prime costs and conversion costs . Prime costs are costs that include the primary (or direct) product costs: direct materials and direct labor. Conversion costs are costs that include the expenses necessary to convert direct materials into a finished product: direct labor and manufacturing overhead. Their relationship is shown in Figure 4.4 . Job order costing systems assign costs directly to the product by assigning direct materials and direct labor to the work in process (WIP) inventory. As you learned in Building Blocks of Managerial Accounting , direct materials are the components that can be directly traced to the products produced, whereas direct labor is the labor cost that can be directly traced to the products produced. Material and labor costs that cannot be traced directly to the product produced are included in the overhead costs that are allocated in the production costing process. Overhead is applied to each product based on an activity base, which will be explained in Compute a Predetermined Overhead Rate and Apply Overhead to Production . The assignment of direct materials and direct labor to each production unit illustrates the job order costing system’s focus on prime costs, in contrast to the process costing system, which assigns costs to the department and focuses on direct materials and conversion costs, which are composed of a combination of direct labor and overhead. Process costs will be demonstrated in Process Costing . Selling and Administrative Costs Selling and administrative costs (S&A) are period costs, and these costs are expensed as incurred, instead of being included in the product’s costs, as they move through the relevant inventory accounts. A period cost is a cost tied to a specific time period, such as a month, quarter, or year, instead of being associated with a particular job order. For example, if a company paid an insurance company $12,000 for one year’s liability insurance coverage, the first month’s expense would be $1,000. This expense would not be related to a particular job order, but instead would be classified as a period cost, and in this case recorded monthly as an administrative expense. Selling costs are the expenses related to the promotion and sale of the company’s products, whereas administrative costs are the expenses related to the operations of the company. The S&A costs are considered period costs because they include costs of departments not directly associated with manufacturing but necessary to operate the business. Some examples include research and development costs, marketing costs, sales commissions, administration building rent, the CEO’s salary expense, and accounting, payroll, and IT department expenses. Your Turn Maria’s Market A grocery store’s analysis of a recent customer survey finds an increasing number of customers interested in being able to custom-order meals to go. Maria sees this as an opportunity to enter a niche market for busy families or individuals who want home-cooked meals with a variety of options and combinations, but who have little time. Maria already has an expansive deli, bakery, and prepared foods section in the store and sees this opportunity as a viable option to increase sales and its customer base. With meals to go, customers can choose from an array of options and can indicate the quantity of each item and the time of pickup. The customer simply pulls up in a designated spot at Maria’s and the food is brought to their car, packaged, and ready to take home to enjoy. What type of costing system will work best for the Maria’s Market? What sales price information, cost information, and other options are important to this decision? Solution A job order cost system will work well for this store. In addition to specific price and cost, these are other important considerations. The optimal sales price should be set to encourage customers to purchase the meals. The materials, labor, and overhead cost should be considered for each meal option. Direct material costs may include the cost of the protein, grain, and vegetable option, as well as the cost of the packing containers. The direct labor cost is for employees who are directly involved in preparing the meals. Manufacturing overhead includes the cost of gloves used when preparing the meals, the cost of employees who support but are not directly involved in preparing the meals, and the cost to operate the oven. The cost of the various meal options should all be less than the sales price. The meal options should change to take advantage of seasonal items. There may be a need to vary the sales price, depending on the combinations selected. Recording Costs in Job Order Costing versus Process Costing Both job order costing and process costing track the costs of materials, labor, and overhead as components of virtually all products. The process of production does not change because of the costing method: The costing method is chosen based on the process of production and is intended to provide the most accurate representation of the costs incurred in the production process. Maintaining accounting records for each system has its advantages. A job order costing system uses a job cost sheet to keep track of individual jobs and the direct materials, direct labor, and overhead associated with each job. The focus of a job order costing system is tracking costs per job, since each job is unique and therefore has different costs relative to other jobs. Maintaining this information is typically more expensive than process costing, and it is often used for the production of smaller, more individualized jobs because the benefit of knowing the cost of each product outweighs the additional cost of maintaining a job order costing system. In contrast, a process costing system does not need to maintain the cost for individual jobs because the jobs use a continual system of production, and the items are typically not significantly unique but instead are basically equivalent. The accounting emphasis is in keeping records for the individual departments, which is useful for large batches or runs. Process costing is the optimal system to use when the production process is continuous and when it is difficult to trace a particular input cost to an individual product. Process costing systems assign costs to each department as the costs are incurred. The costs to produce one unit are calculated, based on the information from the production department. Therefore, the focus of process costing systems is on measuring and assigning the conversion costs to the proper department in order to best determine the cost of individual units. Under either costing method, accounting theory explains why it is important to understand when costs become expenses. A primary reason for separating production costs from other company expenses is the expense recognition principle , which requires costs to be expensed when they match the revenue being earned and to separate the costs of production from other costs for the proper timing of recognition of expenses. Think about measuring the profit from the sale of an item, say a TV, in a nonmanufacturing environment. It is logical to subtract the costs associated with buying the TV in order to determine the profit, before applying other costs from that sale. Suppose the TV was purchased as inventory by the store in January and sold to a customer in March. This requires that the cost of the TV not be recorded as an expense (cost of goods sold) until March, when the sale from the TV is recorded, thus matching the revenue with the expense. Until that time, the TV and its cost are considered inventory. This same idea applies to the manufacturing process. Per the expense recognition principle, product costs—the direct materials, direct labor, and manufacturing overhead incurred to produce the job—are expensed on the income statement for the period of the sale as cost of goods sold when the completed job is sold. If the products are not sold, their costs remain in ending inventory. Prior to the sale of the product, separating production costs and assigning them to the product results in these costs remaining with the inventory. Until they are sold, the costs incurred are reflected in an assortment of inventory accounts, such as raw materials inventory, work in process inventory, and finished goods inventory. In contrast, period costs are not directly related to the production process and are expensed during the period in which they are incurred. This approach matches administrative and other expenses shown on the income statement in the same period in which the company earns income. 4.2 Describe and Identify the Three Major Components of Product Costs under Job Order Costing In order to set an appropriate sales price for a product, companies need to know how much it costs to produce an item. Just as a company provides financial statement information to external stakeholders for decision-making, they must provide costing information to internal managerial decision makers. Virtually every tangible product has direct materials, direct labor, and overhead costs that can include indirect materials and indirect labor, along with other costs, such as utilities and depreciation on production equipment. To account for these and inform managers making decisions, the costs are tracked in a cost accounting system. While the flow of costs is generally the same for all costing systems, the difference is in the details: Product costs have material, labor, and overhead costs, which may be assessed differently. In most production facilities, the raw materials are moved from the raw materials inventory into the work in process inventory . The work in process involves one or more production departments and is where labor and overhead convert the raw materials into finished goods. The movement of these costs through the work in process inventory is shown in Figure 4.5 . At this stage, the completed products are transferred into the finished goods inventory account. When the product is sold, the costs move from the finished goods inventory into the cost of goods sold. While many types of production processes could be demonstrated, let’s consider an example in which a contractor is building a home for a client. The accounting system will track direct materials, such as lumber, and direct labor, such as the wages paid to the carpenters constructing the home. Along with these direct materials and labor, the project will incur manufacturing overhead costs, such as indirect materials, indirect labor, and other miscellaneous overhead costs. Samples of these costs include indirect materials, such as nails, indirect labor, such as the supervisor’s salary, assuming that the supervisor is overseeing several projects at the same time, and miscellaneous overhead costs such as depreciation on the equipment used in the construction project. As direct materials, direct labor, and overhead are introduced into the production process, they become part of the work in process inventory value. When the home is completed, the accumulated costs become part of the finished goods inventory value, and when the home is sold, the finished goods value of the home becomes the cost of goods sold. Figure 4.6 illustrates the flow of these costs through production. The three general categories of costs included in manufacturing processes are direct materials , direct labor , and overhead . Note that there are a few exceptions, since some service industries do not have direct material costs, and some automated manufacturing companies do not have direct labor costs. For example, a tax accountant could use a job order costing system during tax season to trace costs. The one major difference between the home builder example and this one is that the tax accountant will not have direct material costs to track. The few assets used will typically be categorized as overhead. A benefit of knowing the production costs for each job in a job order costing system is the ability to set appropriate sales prices based on all the production costs, including direct materials, direct labor, and overhead. The unique nature of the products manufactured in a job order costing system makes setting a price even more difficult. For each job, management typically wants to set the price higher than its production cost. Even if management is willing to price the product as a loss leader, they still need to know how much money will be lost on each product. To achieve this, management needs an accounting system that can accurately assign and document the costs for each product. If you’re not familiar with the concept of a loss leader, a simple example might help clarify the concept. A loss leader is a product that is sold at a price that is often less than the cost of producing it in order to entice you to buy accessories that are necessary for its use. For example, you might pay $50 or $60 for a printer (for which the producer probably does not make any profit) in order to then sell you extremely expensive printer cartridges that only print a few pages before they have to be replaced. However, even pricing a product as a loss leader requires analysis of the three categories of costs: direct materials, direct labor, and overhead. Direct Materials Direct materials are those materials that can be directly traced to the manufacturing of the product. Some examples of direct materials for different industries are shown in Table 4.2 . In order to respond quickly to production needs, companies need raw materials inventory on hand. While production volume might change, management does not want to stop production to wait for raw materials to be delivered. Further, a company needs raw materials on hand for future jobs as well as for the current job. The materials are sent to the production department as it is needed for production of the products. Common Direct Materials by Industry Industry Direct Materials Automotive Iron, aluminum, glass, rubber Cell phones Glass, various metals, plastic Furniture Wood, leather, vinyl Jewelry Gold, silver, diamonds, rubies Pharmaceuticals Natural or synthetic biological ingredients Table 4.2 Each job begins when raw materials are put into the work in process inventory. When the materials are requested for production, a materials requisition slip is completed and shows the exact items and quantity requested, along with the associated cost. The completed form is signed by the requestor and approved by the manager responsible for the budget. Returning to the example of Dinosaur Vinyl’s order for Macs & Cheese’s stadium sign, Figure 4.7 shows the materials requisition form for Job MAC001. This form indicates the quantity and specific items to be put into the work in process. It also transfers the cost of those items to the work in process inventory and decreases the raw materials inventory by the same amount. The raw materials inventory department maintains a copy to document the change in inventory levels, and the accounting department maintains a copy to properly assign the costs to the particular job. Dinosaur Vinyl has a beginning inventory of $1,000 in raw materials: vinyl , and $300 in each of its ink inventories: raw materials: black ink , raw materials: red ink , and raw materials: gold ink . In order to have enough inventory on hand for all of its jobs, it purchases $10,000 in vinyl and $500 in black ink. The T-accounts in Figure 4.8 show the stated beginning debit balances. An additional $10,000 of vinyl and $500 of black ink were then purchased for anticipated use, providing the demonstrated final account balances. The red ink and gold ink balances did not change, since no additional quantities were purchased. The beginning balances and purchases in each of these accounts are illustrated in Figure 4.8 . Traditional billboards with the design printed on vinyl include direct materials of vinyl and printing ink, plus the framing materials, which consist of wood and grommets. The typical billboard sign is 14 feet high by 48 feet wide, and Dinosaur Vinyl incurs a vinyl cost of $300 per billboard. The price for the ink varies by color. For this job, Dinosaur Vinyl needs two units of black ink at a cost of $50 each, one unit of red ink and one unit of gold ink at a cost of $60 each, twelve grommets at a cost of $10 each, and forty units of wood at a cost of $1.50 per unit. The total cost of direct materials is $700, as shown in Figure 4.9 . Some items are more difficult to measure per unit, such as adhesives and other materials not directly traceable to the final product. Their costs are assigned to the product as part of manufacturing overhead as indirect materials. When Dinosaur Vinyl requests materials to complete Job MAC001, the materials are moved from raw materials inventory to work in process inventory . We will use the beginning inventory balances in the accounts that were provided earlier in the example. The requisition is recorded on the job cost sheet along with the cost of the materials transferred. The costs assigned to job MAC001 are $300 in vinyl, $100 in black ink, $60 in red ink, and $60 in gold ink. During the finishing stages, $120 in grommets and $60 in wood are requisitioned and put into work in process inventory. The costs are tracked from the materials requisition form to the work in process inventory and noted specifically as part of Job MAC001 on the preceding job order cost sheet. The movement of goods is illustrated in Figure 4.10 . Each of the T-accounts traces the movement of the raw materials from inventory to work in process. The vinyl and ink were used first to print the billboard, and then the billboard went to the finishing department for the grommets and frame, which were moved to work in process after the vinyl and ink. The final T-account shows the total cost for the raw materials placed into work in process on April 2 (vinyl and ink) and on April 14 (grommets and wood). The journal entries to reflect the flow of costs from raw materials to work in process to finished goods are provided in the section describing how to Prepare Journal Entries for a Job Order Cost System . Direct Labor Direct labor is the total cost of wages, payroll taxes, payroll benefits, and similar expenses for the individuals who work directly on manufacturing a particular product. The direct labor costs for Dinosaur Vinyl to complete Job MAC001 occur in the production and finishing departments. In the production department, two individuals each work one hour at a rate of $15 per hour, including taxes and benefits. The finishing department’s direct labor involves two individuals working one hour each at a rate of $18 per hour. Figure 4.11 shows the direct labor costs for Job MAC001. Job MAC001 is also manufactured with the work of individuals whose contributions cannot be directly traced to the product: These indirect labor costs are assigned to the product as part of manufacturing overhead. A company can use various methods to trace employee wages to specific jobs. For example, employees may fill out time tickets that include job numbers and time per job, or workers may scan bar codes of specific jobs when they begin a job task. Figure 4.12 shows what time tickets might look like on Job MAC001. Please note that in the employee time tickets that are displayed, each employee worked on more than one job. However, we are only going to track the expenses for Job MAC001. When the accounting department processes time tickets, the costs are assigned to the individual jobs, resulting in labor costs being recorded on the work in process inventory, as shown in Figure 4.13 . Manufacturing Overhead Recall that the costs of a manufactured item are direct materials, direct labor, and manufacturing overhead. Costs that support production but are not direct materials or direct labor are considered overhead. Manufacturing overhead has three components: indirect materials, indirect labor, and overhead. Indirect Materials Indirect material costs are derived from the goods not directly traced to the finished product, like the sign adhesive in the Dinosaur Vinyl example. Tracking the exact amount of adhesive used would be difficult, time consuming, and expensive, so it makes more sense to classify this cost as an indirect material. Indirect materials are materials used in production but not traced to specific products because the net informational value from the time and effort to trace the cost to each individual product produced is impossible or inefficient. For example, a furniture factory classifies the cost of glue, stain, and nails as indirect materials. Nails are often used in furniture production; however, one chair may need 15 nails, whereas another may need 18 nails. At a cost of less than one cent per nail, it is not worth keeping track of each nail per product. It is much more practical to track how many pounds of nails were used for the period and allocate this cost (along with other costs) to the overhead costs of the finished products. Indirect Labor Indirect labor represents the labor costs of those employees associated with the manufacturing process, but whose contributions are not directly traceable to the final product. These would include the costs of the factory floor supervisor, the factory housekeeping staff, and factory maintenance workers. For Dinosaur Vinyl, for example, labor costs for the technician who maintains the printers would be indirect labor. It would be too time consuming to determine how much of the technician’s time is attributable to each sign being produced. It makes much more sense to classify that labor expense as indirect labor. It is important to understand that the allocation of costs may vary from company to company. What may be a direct labor cost for one company may be an indirect labor cost for another company or even for another department within the same company. Deciding whether the expense is direct or indirect depends on its task. If the employee’s work can be directly tied to the product, it is direct labor. If it is tied to the factory but not to the product, it is indirect labor. If it is tied to the marketing department, it is a sales and administrative expense, and not included in the cost of the product. For example, salaries of factory employees assembling parts are direct labor, salaries of factory employees performing maintenance are indirect labor, and salaries of employees in the marketing department are sales and administration expenses. Overhead The last category of manufacturing overhead is the overhead itself. These costs are necessary for production but not efficient to assign to individual product production. Examples of typical overhead costs are production facility electricity, warehouse rent, and depreciation of equipment. But note that while production facility electricity costs are treated as overhead, the organization’s administrative facility electrical costs are not included as as overhead costs. Instead, they are treated as period costs, as office rent or insurance would be. When both administrative and production activities occur in a common building, the production and period costs would be allocated in some predetermined manner. For example, if a 10,000 square foot building were physically allocated at 4,000 square feet for administrative purposes and 6,000 square feet for production, a company might allocate its annual $30,000 property tax expense on a 40%/60% basis, or $12,000 as a period cost for the administrative offices and a production (overhead) cost of $18,000. Link to Learning Do you know of a restaurant that was doing really well until it moved into a larger space? Often this happens because the owners thought their profits could handle the costs of the increased space. Unfortunately, they were not really aware of the production costs. Keeping track of product costs is critical for pricing and cost control. Read advice from restaurant owner John Gutekanst about the importance of understanding food costs and his approach to account for these in his pizzeria. Accounting for Manufacturing Overhead In all costing systems, the expense recognition principle requires costs to be recorded in the period in which they are incurred. The costs are expensed when matched to the revenue with which they are associated; this is commonly referred to as having the expenses follow the revenues . This explains why raw material purchases are not assigned to the job until the materials are requested. When companies use an inventory account, the product costs are expensed when the inventory is sold. It is common to have an item produced in one year, such as 2017, and expensed as cost of goods sold in a later year, such as 2018. In addition to the previously mentioned revenue recognition treatment, this treatment is justified under GAAP’s matching principle . If the inventory has not been sold, the company has an inventory asset rather than an expense. The expense recognition principle also applies to manufacturing overhead costs. The manufacturing overhead is an expense of production, even though the company is unable to trace the costs directly to each specific job. For example, the electricity needed to run production equipment typically is not easily traced to a particular product or job, yet it is still a cost of production. As a cost of production, the electricity—one type of manufacturing overhead—becomes a cost of the product and part of inventory costs until the product or job is sold. Fortunately, the accounting system keeps track of the manufacturing overhead, which is then applied to each individual job in the overhead allocation process. Ethical Considerations Ethical Job Order Costing Job order costing requires the assignment of direct materials, direct labor, and overhead to each production unit. The primary focus on costs allows some leeway in recording amounts because the accountant assigns the costs. When jobs are billed on a cost-plus-fee basis, management may be tempted to overcharge the cost of the job. Cost-based contracts may include a guaranteed maximum, time and materials, or cost reimbursable contract. An example is the design and delivery of a corporate training program. The training company may charge for the hours worked by instructors in preparation and delivery of the course, plus a fee for the course materials. One major issue in all of these contracts is adding too much overhead cost and fraudulent invoicing for unused materials or unperformed work by subcontractors. Management might be tempted to direct the accountant to avoid the appearance of going over the original estimate by manipulating job order costing. It is the accountant’s job to ensure that the amounts recorded in the accounting system fairly represent the economic activity of the company, and the fair and proper allocation of costs. Managers use the information in the manufacturing overhead account to estimate the overhead for the next fiscal period. This estimated overhead needs to be as close to the actual value as possible, so that the allocation of costs to individual products can be accurate and the sales price can be properly determined. Properly allocating overhead to the individual jobs depends on finding a cost driver that provides a fair basis for the allocation. A cost driver is a production factor that causes a company to incur costs. An example would be a bakery that produces a line of apple pies that it markets to local restaurants. To make the pies requires that the bakery incur labor costs, so it is safe to say that pie production is a cost driver. It should also be safe to assume that the more pies made, the greater the number of labor hours experienced (also assuming that direct labor has not been replaced with a greater amount of automation). We assume, in this case, that one of the marketing advantages that the bakery advertises is 100% handmade pastries. In traditional costing systems, the most common activities used as cost drivers are direct labor in dollars, direct labor in hours, or machine hours. Often in the production process, there is a correlation between an increase in the amount of direct labor used and an increase in the amount of manufacturing overhead incurred. If the company can demonstrate such a relationship, they then often allocate overhead based on a formula that reflects this relationship, such as the upcoming equation. In the case of the earlier bakery, the company could determine an overhead allocation amount based on each hour of direct labor or, in other cases, based on the ratio of anticipated total direct labor costs to total manufacturing overhead costs. For example, assume that the company estimates total manufacturing overhead for the year to be $400,000 and the direct labor costs for the year to be $200,000. This relationship would lead to $2.00 of applied overhead for each $1.00 of direct labor incurred. The manufacturing overhead cost can be calculated and applied to each specific job, based on the direct labor costs. The formula that represents the overhead allocation relationship is shown, and it is the formula for overhead allocation: For example, Dinosaur Vinyl determined that the direct labor cost is the appropriate driver to use when establishing an overhead rate. The estimated annual overhead cost for Dinosaur Vinyl is $250,000. The total direct labor cost is estimated to be $100,000, so the allocation rate is computed as shown: Since the direct labor expense for MAC001 is $66, the overhead allocated is $66 times the overhead application rate of $2.50 per direct labor dollar, or $165, as shown: Figure 4.14 shows the journal entry to record the overhead allocation. Think It Through Franchise or Unique Venture? You are deciding whether to purchase a pizza franchise or open your own restaurant specializing in pizza. List the expenses necessary to sell pizza and identify them as a fixed cost or variable cost; as a manufacturing cost or sales and administrative costs; and as a direct materials, direct labor, or overhead. For each overhead item, state whether it is an indirect material expense, indirect labor expense, or other. For each cost, identify its origination in a job order costing environment. 4.3 Use the Job Order Costing Method to Trace the Flow of Product Costs through the Inventory Accounts Job order costing can be used for many different industries, and each industry maintains records for one or more inventory accounts. The manufacturing industry keeps track of the costs of each inventory account as the product is moved from raw materials inventory into work in process, through work in process, and into the finished goods inventory. Conversely, typical companies in the merchandising industry sell products they do not manufacture and purchase their inventory in an already completed state. It is relatively easy to keep track of the inventory cost for a merchandising company through its application of first-in/first-out (FIFO), last-in/last-out (LIFO), weighted average, or specific identification inventory techniques on the unsold items. The primary difference in the four methods is the valuation of the cost of goods sold and the remaining ending inventory valuation, assuming that the company did not sell 100% of the inventory that they had available for sale during a given period. Companies are allowed to choose the method that they feel best represents their cost flows through their cost of goods sold and their ending inventory balances. Not all service companies have inventory, and those companies do not have direct materials nor do they consider their work in process their inventory, since their final product is often an intangible asset, such as a legal document or tax return. Regardless of whether the service has inventory accounts, service companies all keep track of the direct labor and overhead costs incurred while completing each job in progress. Inventory is an asset reported on the balance sheet, and each company needs to maintain accurate records for the cost of each type of inventory: raw materials inventory , work in process inventory , and finished goods inventory . All three costs are computed in a similar manner. You can see in Figure 4.15 that the general format is the same for maintaining all accounts, whether the company uses a job order, process, or hybrid cost system. Each inventory account starts with a beginning balance at the start of an accounting period. During the period, if additional inventory is purchased, the new inventory amount is added to the beginning balance to calculate the total inventory available for use or sale. The ending inventory balance at the end of the accounting period can then be subtracted from the inventory available for use, and the total represents the cost of the inventory used during the period. For example, if the beginning inventory balance were $400, and the company bought an additional $1,000, it would have $1,400 of inventory available for use. If the ending inventory balance were $500, the amount of inventory used during the period would be $900 ($400 + $1,000 = $1,400 – $500 = $900). Raw Materials Inventory Raw materials inventory is the total cost of materials that will be used in the production process. Usually, several accounts make up the raw materials inventory, and these can be actual accounts or accounts subsidiary to the general raw materials inventory account. In our example, Dinosaur Vinyl has several raw materials accounts: vinyl, red ink, black ink, gold ink, grommets, and wood. Within the raw materials inventory account, purchases increase the inventory, whereas raw materials sent into production reduce it. It is easy to reconcile the amount of ending inventory and the cost of direct materials used in production, since the materials requisition form ( Figure 4.7 ) keeps track of the inventory requested and sent into each specific job. Since the costs are transferred with production, the calculation shows the amount of materials used in production: Work in Process Inventory In a job order cost system, the balance in the work in process inventory account is continually updated as job costs are recorded and is the total of all unfinished jobs, as shown on the individual job cost sheets. The production cycle is a continuous cycle that begins with raw materials being transferred to work in process, moving through production, and ending as finished goods inventory. Typically, as goods are being produced, additional jobs are being started and finished, and the work in process inventory includes unit costs of jobs still in production at the end of the accounting period. At the end of the accounting cycle, there will be jobs that remain unfinished in the production cycle, and these represent the work in process inventory . The costs on the job order cost sheet help reconcile the cost of the items transferred to the finished goods inventory and the cost of the work in process inventory. For example, Dinosaur Vinyl has completed Job MAC001. The total cost of $931 is transferred to the finished goods inventory: At this point, we need to examine an important component of the costing process. The cost of goods manufactured (COGM) is the costs of all of the units that a company completed and transferred to the finished goods inventory during an accounting period. Obviously, the cost of goods manufactured is not just a single number that can be pulled from one location. We have to look at all costs included in the manufacturing process to determine the cost of goods manufactured. The calculation begins with the beginning balance in the work in process inventory, incorporates the new production costs incurred during the current period (typically a year), and then subtracts the ending balance in the work in process inventory since these costs will be included in the subsequent accounting period’s cost of goods manufactured, as shown: Finished Goods Inventory After each job has been completed and overhead has been applied, the product is transferred to the finished goods inventory where it stays until it is sold. As each job is transferred, the costs are summarized and transferred as well, and the job cost sheet is completed to show the actual production cost of the product and the sales price of the items produced. A job order cost system continually updates each job cost sheet as materials, labor, and overhead are added. As a result, all inventory accounts are constantly maintained. The materials inventory balance is continually updated, as materials are purchased and requisitioned for individual jobs. The work in process inventory and finished goods inventory are master accounts, and their balances are determined by adding the total of the job cost sheets. The total of the incomplete jobs becomes the total work in process inventory, and the total of the completed and unsold jobs becomes the total of the finished goods inventory. Similar to the raw materials and work in process inventories, the cost of goods sold can be calculated as shown: Cost of Goods Sold The cost of goods sold is the manufacturing cost of the items sold during the period. It is calculated by adding the beginning finished goods inventory and the cost of goods manufactured to arrive at the cost of goods available for sale. The cost of goods available for sale less the ending inventory results in the cost of goods sold. In our example, when the sale has occurred, the goods are transferred to the buyer, and the product is transferred from the finished goods inventory to the cost of goods sold. A corresponding entry is also made to record the sale. Dinosaur Vinyl’s sales price for Job MAC001 was $2,000, and its cost of goods sold was $931: Figure 4.16 shows the flow to cost of goods sold. Your Turn Tracking the Flow with Selected T-Accounts Use the transaction letters to show the flow in and out of the T-accounts. Note: some items may be used more than once. Also, not every possible T-account entry is required in this exercise. For example, for the purchase of raw materials, the credit entry for either cash or accounts payable is not required. Purchase raw materials inventory Factory wage expense incurred Issue raw materials inventory to Job P33 Factory wage allocated to Job P33 Factory wage allocated to overhead Job P33 completed Job P33 sold Solution 4.4 Compute a Predetermined Overhead Rate and Apply Overhead to Production Job order cost systems maintain the actual direct materials and direct labor for each individual job. Since production consists of overhead—indirect materials, indirect labor, and other overhead—we need a methodology for applying that overhead. Unfortunately, the nature of indirect material, indirect labor, and other overhead expenses makes it impossible to determine the exact amount of overhead for each specific job. For example, how do you know the cost of electricity and heat for manufacturing one job? And, if you did, is it fair to say products manufactured in January are more expensive than the same product manufactured in March because of heat expense? Fundamental Characteristics of the Overhead Determination Environment Added to these issues is the nature of establishing an overhead rate , which is often completed months before being applied to specific jobs. Establishing the overhead allocation rate first requires management to identify which expenses they consider manufacturing overhead and then to estimate the manufacturing overhead for the next year. Manufacturing overhead costs include all manufacturing costs except for direct materials and direct labor. Therefore, in order to estimate manufacturing overhead, management must estimate the future purchase prices of dozens, or sometimes hundreds, of individual components, such as utilities, raw materials, contract labor, or diesel fuel. Estimating overhead costs is difficult because many costs fluctuate significantly from when the overhead allocation rate is established to when its actual application occurs during the production process. You can envision the potential problems in creating an overhead allocation rate within these circumstances. Before demonstrating the calculation of a predetermined overhead allocation rate , let’s review the basic principles of revenue recognition and expense. In accounting, there are three ways to recognize expenses: Direct relationship between the expense and the associated revenue. This method is used for many costs, and the expense is recognized when a direct relationship exists. For example, sales commission expenses can be directly traced to product sales, and a commission expense is recorded when a sale is made. Systematic and rational allocation of expenses. This approach is used when costs exist and there is an expected benefit, even though the costs cannot be directly traced to the benefit. The assigning of expenses to a product or time period must be done in an objective and consistent manner. Examples of such expenses would include equipment rental for a factory or property insurance for the factory. Both of these expenses (direct relationship and systematic and rational) are also examples of the types of expenses that compose manufacturing overhead. An example of the current revenue recognition principle is a company paying $4,800 a year for property insurance. Since production rates can vary month to month, most producers would allocate $400 each month for property insurance, and this cost would be incorporated into the total overhead costs anticipated when estimating a manufacturing overhead allocation rate. The direct benefit is that the product will be sold and the revenue recognized. The overhead is associated but cannot be directly traced to an individual product, so the overhead expenses need to be assigned in a systematic and rational manner. Immediate recognition. This method is used when expenses exist but there is no direct expected benefit. In this case, the expense is recognized immediately. For example, research and development costs are necessary expenses but cannot be traced to a specific product, so they are expensed as incurred. The allocation of overhead to the cost of the product is also recognized in a systematic and rational manner. The expected overhead is estimated, and an allocation system is determined. The actual costs are accumulated in a manufacturing overhead account. The overhead is then applied to the cost of the product from the manufacturing overhead account. The overhead used in the allocation is an estimate due to the timing considerations already discussed. The application rate that will be used in a coming period, such as the next year, is often estimated months before the actual overhead costs are experienced. Often, the actual overhead costs experienced in the coming period are higher or lower than those budgeted when the estimated overhead rate or rates were determined. At this point, do not be concerned about the accuracy of the future financial statements that will be created using these estimated overhead allocation rates. You will learn in Determine and Disposed of Underapplied or Overapplied Overhead how to adjust for the difference between the allocated amount and the actual amount. Despite improvements in technology and information flow, using the actual overhead to calculate the application rate is usually not possible because the actual overhead information is available too late for management to make decisions. Also, as you will learn, the results of the actual overhead costs, if they were available, could be misleading. Therefore, most manufacturing companies use predetermined overhead rates for these reasons: Overhead costs are not uniform throughout the year. An example is electricity costs that vary by weather and time of day. Some overhead costs are fixed, and the cost per unit varies with production. For example, rent may be $1,000 per month. If 500 units were made during one month, and 2,000 units were made the next month, the cost per unit would vary from $2 per unit to $0.50 per unit. The total number of units produced varies and is often known sooner than the cost of overhead. For example, a company may know it will have a contract to produce 100 custom units long before it knows the utility costs for the next year. As previously described, a predetermined overhead rate is established prior to the beginning of the fiscal year and typically is not changed during the year. The predetermined rate is calculated as shown and is used to apply overhead costs to work in process: Concepts In Practice Overhead in the Movie Industry The movie industry uses job order costing, and studios need to allocate overhead to each movie. Their amount of allocated overhead is not publicly known because while publications share how much money a movie has produced in ticket sales, it is rare that the actual expenses are released to the public. It has been speculated that Star Wars: The Force Awakens cost $201,000,000, with $30,000,000 considered overhead. Studios have estimated that the higher the movie expenses, the more studio overhead is required, and it has also been estimated that 10% of the total cost is assigned to studio overhead. Determining Estimated Overhead Cost The estimated or budgeted overhead is the amount of overhead determined during the budgeting process and consists of manufacturing costs but, as you have learned, excludes direct materials and direct labor. Examples of manufacturing overhead costs include indirect materials, indirect labor, manufacturing utilities, and manufacturing equipment depreciation. Another way to view it is overhead costs are those production costs that are not categorized as direct materials or direct labor. Selecting an Estimated Activity Base As you have learned, the overhead needs to be allocated to the manufactured product in a systematic and rational manner. This allocation process depends on the use of a cost driver, which drives the production activity’s cost. Examples can include labor hours incurred, labor costs paid, amounts of materials used in production, units produced, or any other activity that has a cause-and-effect relationship with incurred costs. Direct labor hours, direct labor dollars, or machine hours are often chosen as the allocation base because those costs are associated with each product, and as the activity increases, so does the manufacturing overhead. In other words, the products that involve more direct labor hours, direct labor dollars, or machine hours also increase utility expenses, supervisor time (and thus indirect labor), equipment usage and the related depreciation expense, and so forth. Traditionally, direct labor hours were used as the activity base, but technology continually decreases the amount of direct labor used in production, and machine hours or units produced have become more common activity bases. Management analyzes the costs and selects the activity as the estimated activity base because it drives the overhead costs of the unit. Computing a Predetermined Overhead Rate Dinosaur Vinyl uses the expenses from the prior two years to estimate the overhead for the upcoming year to be $250,000, as shown in Figure 4.17 . Dinosaur Vinyl also used its payroll records to estimate that it will spend $100,000 on direct labor. Using the predetermined overhead rate calculation, the overhead rate is $2.50 per direct labor dollar: Over the fiscal year, the actual costs are recorded as debits into the account called manufacturing overhead. When the overhead is applied to the jobs, the amount is first calculated using the application rate. If the total labor paid for the job is $66, the overhead applied to the job is $2.50 times that amount, or $165. The entry to record the overhead for Job MAC001 is: That amount is added to the cost of the job, and the amount in the manufacturing overhead account is reduced by the same amount. At the end of the year, the amount of overhead estimated and applied should be close, although it is rare for the applied amount to exactly equal the actual overhead. For example, Figure 4.18 shows the monthly costs, the annual actual cost, and the estimated overhead for Dinosaur Vinyl for the year. While the total amounts are close to each other, they are not exact. Calculating Manufacturing Overhead Cost for an Individual Job Figure 4.18 shows the monthly manufacturing actual overhead recorded by Dinosaur Vinyl. As explained previously, the overhead is allocated to the individual jobs at the predetermined overhead rate of $2.50 per direct labor dollar when the jobs are complete. When Job MAC001 is completed, overhead is $165, computed as $2.50 times the $66 of direct labor, with the total job cost of $931, which includes $700 for direct materials, $66 for direct labor, and $165 for manufacturing overhead. Link to Learning Companies need to make certain the sales price is higher than the prime costs and the overhead costs. This can be a difficult task in industries in which overhead costs change. In some industries, the company has no control over the costs it must pay, like tire disposal fees. To ensure that the company is profitable, an additional cost is added and the price is modified as necessary. In this example, the guarantee offered by Discount Tire does not include the disposal fee in overhead and increases that fee as necessary. 4.5 Compute the Cost of a Job Using Job Order Costing To summarize the job order cost system , the cost of each job includes direct materials, direct labor, and manufacturing overhead. While the product is in production, the direct materials and direct labor costs are included in the work in process inventory. The direct materials are requested by the production department, and the direct material cost is directly attached to each individual job, as the materials are released from raw materials inventory. The cost of direct labor is recorded by the employees and assigned to each individual job. When the allocation base is known, usually when the product is completed, the overhead is allocated to the product on the basis of the predetermined overhead rate. Link to Learning The construction industry typically uses job order costing and accounts for its costing in a manner similar to the businesses profiled in this chapter. Determining the Costs of an Individual Job Using Job Order Costing When a job is completed, the costs of the job—the direct materials, direct labor, and manufacturing overhead—are totaled on the job cost sheet, and the total amount is transferred to finished goods at the same time the product is transferred, either physically or legally, such as in the case of a home built by a contractor. Finally, when the product is sold, the sale is recorded at the sale price, while the cost is transferred from finished goods inventory to the cost of goods sold expense account. Figure 4.19 shows the flow of costs from raw materials inventory to cost of goods sold. At all points in the process, the work in process should include the cost of direct materials and direct labor. When the job is completed and overhead assigned, the overhead allocation increases the cost of the work in process inventory. The cost of each individual job is maintained on a job cost sheet, and the total of all the work in process job cost sheets equals the work in process inventory and the statement of cost of goods manufactured, as you have learned. A job cost sheet is a subsidiary ledger that identifies the individual costs for each job. Figure 4.20 shows the job cost sheet for Job MAC001. Sample Cost Information for Dinosaur Vinyl Dinosaur Vinyl worked on three jobs during the month: POR143, MAC001, and TRJ441, and a fourth Job SWM505 had been finished and moved to the finished goods inventory account during the previous month. At the beginning of the month, the company had a beginning raw materials inventory balance of $2,500, and during the month, it purchased an additional $10,500, giving it a total of $13,000 in raw materials available for use in production. The following example will examine four different production jobs. Each of the four will be at beginning stages at either the beginning of the current month or the end of the current month. Job POR 143: This job was the only work in process inventory at the beginning of the current month, and it had $1,000 in direct material costs, and $0 of direct labor costs already allocated to the work in process inventory. During the current month, additional direct materials of $200 and direct labor of $150 were added to POR143. An overhead cost of $375 was applied to POR143 at the predetermined overhead rate of $2.50 per direct labor dollar. It was finished during the month and transferred to the finished goods inventory. The sale was not finalized during the month, so it continues to be part of the finished goods inventory. Job MAC 001: This job was started and completed during the month. Since the job began in and was completed in the same month, there was no beginning balance in the work in process inventory. During the month it incurred $700 in direct materials costs, $66 in direct labor, and $165 of overhead applied to the job before it was transferred to the finished goods inventory upon completion. The sale was finalized during the month at a sale price of $2,000, so the costs were transferred from finished goods inventory to cost of goods sold. Job TRJ441: This job was started during the current month. Its costs consist of $500 in direct material cost, $150 in direct labor expenses, and $375 in applied overhead. The job remains in the work in process inventory awaiting assembly. Job SWM505: At the beginning of the month, this job was completed and already in the finished goods inventory at a cost of $1,531. Since it was completed, it did not incur any additional costs in the current month. It was sold during the month for $3,500, and the costs were transferred from the finished goods inventory to cost of goods sold. The cost of raw materials used is calculated as shown: The individual job cost sheets show the $1,400 worth of materials used in production: The cost of goods manufactured is accounted for as shown: Notice the costs for Job TJR441 are included in the work in process inventory, whereas the costs for POR143 and MAC001 were transferred to the cost of goods manufactured. The costs of the jobs transferred are shown in the cost of goods sold and the finished goods inventory: Mechanics of Job Order Costing for Dinosaur Vinyl The amounts in raw materials, work in process, and finished goods inventories compose the total cost for each account, whereas the job cost sheets contain the costs for each individual job. A summary of the jobs for Dinosaur Vinyl is given in Figure 4.21 . Think It Through Allocating Costs A manufacturing company has incurred these costs: What is the cost allocated to Job A? For any costs not used, explain why they are not used. 4.6 Determine and Dispose of Underapplied or Overapplied Overhead As you’ve learned, the actual overhead incurred during the year is rarely equal to the amount that was applied to the individual jobs. Thus, at year-end, the manufacturing overhead account often has a balance, indicating overhead was either overapplied or underapplied. If, at the end of the term, there is a debit balance in manufacturing overhead, the overhead is considered underapplied overhead . A debit balance in manufacturing overhead shows either that not enough overhead was applied to the individual jobs or overhead was underapplied. If, at the end of the term, there is a credit balance in manufacturing overhead, more overhead was applied to jobs than was actually incurred. This shows the actual amount was overapplied overhead . The actual overhead costs are recorded through a debit to manufacturing overhead. The same account is credited when overhead is applied to the individual jobs in production, as shown: Since the overhead is first recorded in the manufacturing overhead account, then applied to the individual jobs, traced through finished goods inventory, and eventually transferred to cost of goods sold, the year-end balance is eliminated through an adjusting entry, offsetting the cost of goods sold. If manufacturing overhead has a debit balance, the overhead is underapplied, and the resulting amount in cost of goods sold is understated. The adjusting entry is: If manufacturing overhead has a credit balance, the overhead is overapplied, and the resulting amount in cost of goods sold is overstated. The adjusting entry is: Returning to our example, at the end of the year, Dinosaur Vinyl had actual overhead expenses of $256,500 and applied overhead expenses of $250,000, as shown: Since manufacturing overhead has a debit balance, it is underapplied, as it has not been completely allocated. The adjusting journal entry is: If the overhead was overapplied, and the actual overhead was $248,000 and the applied overhead was $250,000, the entry would be: To adjust for overapplied or underapplied manufacturing overhead, some companies have a more complicated, three-part allocation to work in process, finished goods, and cost of goods sold. This method is typically used in the event of larger variances in their balances or in bigger companies. (You will learn more about this in future cost or advanced managerial accounting courses.) Your Turn Kraken Boardsports Kraken Boardsports manufactures winches for snow and ski boarders to snow ski without a mountain or water ski without a lake ( Figure 4.22 ). End-of-year data show these overhead expenses: Kraken Boardsports had 6,240 direct labor hours for the year and assigns overhead to the various jobs at the rate of $33.50 per direct labor hour. How much overhead was overapplied or underapplied during the year? What would be the journal entry to adjust manufacturing overhead? Solution The total overhead incurred is the total of: The total overhead applied is $209,040, which is calculated as: $33.50/direct labor hours × 6,240 direct labor hours. The balance in manufacturing overhead is a debit balance of $210: The adjusting journal entry is: Link to Learning Job order costing and overhead allocation are not new methods of accounting and apply to governmental units as well. See it applied in this 1992 report on Accounting for Shipyard Costs and Nuclear Waste Disposal Plans from the United States General Accounting Office. 4.7 Prepare Journal Entries for a Job Order Cost System Although you have seen the job order costing system using both T-accounts and job cost sheets, it is necessary to understand how these transactions are recorded in the company’s general ledger. Journal Entries to Move Direct Materials, Direct Labor, and Overhead into Work in Process Dinosaur Vinyl keeps track of its inventory and orders additional inventory to have on hand when the production department requests it. This inventory is not associated with any particular job, and the purchases stay in raw materials inventory until assigned to a specific job. For example, Dinosaur Vinyl purchased an additional $10,000 of vinyl and $500 of black ink to complete Macs & Cheese’s billboard. If the purchase is made on account, the entry is as shown: As shown in Figure 4.20 , for the production process for job MAC001, the job supervisor submitted a materials requisition form for $300 in vinyl, $100 in black ink, $60 in red ink, and $60 in gold ink. For the finishing process for Job MAC001, $120 in grommets and $60 in finishing wood were requisitioned. The entry to reflect these actions is: The production department employees work on the sign and send it over to the finishing/assembly department when they have completed their portion of the job. The direct cost of factory labor includes the direct wages paid to the employees and all other payroll costs associated with that labor. Typically, this includes wages and the payroll taxes and fringe benefits directly tied to those wages. The accounting system needs to keep track of the labor and the other related expenses assigned to a particular job. These records are typically kept in a time ticket submitted by employees daily. On April 10, the labor time sheet totaling $30 is recorded for Job MAC001 through this entry: The assembly personnel in the finishing/assembly department complete Job MAC001 in two hours. The labor is recorded as shown: Indirect materials also have a materials requisition form, but the costs are recorded differently. They are first transferred into manufacturing overhead and then allocated to work in process. The entry to record the indirect material is to debit manufacturing overhead and credit raw materials inventory. Indirect labor records are also maintained through time tickets, although such work is not directly traceable to a specific job. The difference between direct labor and indirect labor is that the indirect labor records the debit to manufacturing overhead while the credit is to factory wages payable. Dinosaur Vinyl’s time tickets indicate that $4,000 in indirect labor costs were incurred during the period. The entry is: Dinosaur Vinyl also records the actual overhead incurred. As shown in Figure 4.18 , manufacturing overhead costs of $21,000 were incurred. The entry to record these expenses increases the amount of overhead in the manufacturing overhead account. The entry is: The amount of overhead applied to Job MAC001 is $165. The process of determining the manufacturing overhead calculation rate was explained and demonstrated in Accounting for Manufacturing Overhead . The journal entry to record the manufacturing overhead for Job MAC001 is: Journal Entry to Move Work in Process Costs into Finished Goods When each job and job order cost sheet have been completed, an entry is made to transfer the total cost from the work in process inventory to the finished goods inventory. The total cost of the product for Job MAC001 is $931 and the entry is: Journal Entries to Move Finished Goods into Cost of Goods Sold When the sale has occurred, the goods are transferred to the buyer. The product is transferred from the finished goods inventory to cost of goods sold. A corresponding entry is also made to record the sale. The sign for Job MAC001 had a sales price of $2,000 and a cost of $931. These are the entries to record the transfer of goods and sale to the buyer: The resulting accounting is shown on the company’s income statement: Think It Through Ongoing Overapplied Overhead At the end of each year, manufacturing overhead is analyzed, and an adjusting entry is made to dispose of the under- or overapplied overhead. How would you advise a company that has had overapplied overhead for each of the last five years? 4.8 Explain How a Job Order Cost System Applies to a Nonmanufacturing Environment Job order cost systems can be used beyond the manufacturing realm and are often used in the production of services. The same cost tracking and journaling techniques apply, as the outcome still consists of materials, labor, and overhead. However, the terminology changes in a nonmanufacturing environment. For example, a movie production studio and an accounting firm produce movies and financial statement audits, respectively, instead of manufacturing units. Fundamentals of the Job Order Costing Method for Service Entities Instead of being dependent on materials, service industries depend on labor. Since their work is labor intensive, it makes sense to use labor as an activity base with billable hours often as the best allocation base. For example, in an audit, there often will be several accountants, with differing levels of experience and expertise involved in the assignment. The accounting firms have more billable hours at the staff level and fewer billable hours at the partner level. And since the firm bills the partner’s time at a significantly higher rate than the staff, it makes sense to apply overhead at the billable hours instead of the billable costs. In service industries, there is no manufacturing overhead because they are not manufacturing a product, but instead are providing a service. Accordingly, overhead is called operating overhead . Another terminology difference is the inventory accounts. The jobs are considered movies or assignments in process, and are transferred to a cost of service sold account instead of to a finished goods inventory. Concepts In Practice Tracking Costs in Healthcare Healthcare is one of the industries that keeps track of materials, such as medicine. In this industry, direct labor is shown to the patient as the cost of the provider, such as a physician, physician assistant, or nurse practitioner. Indirect labor includes all other personnel from front desk staff to the nurse who gathers vital signs or a technician who performs tests. Patients do not see the overhead cost on their bill, but it is built into the invoice as part of the practitioner or testing fees. Service Entity Use of a Job Order Costing System To understand how a service provider uses a job order cost system, let’s consider the case of IFixIT. IFixIT Systems is a Sony -authorized repair provider that fixes audiovisual equipment brought in by customers. IFixIT requires customers to pay $50 to diagnose the problem. IFixIt pays its employees $25 per hour and assigns overhead equal to its direct labor cost. The customers’ bills do not show overhead and are instead itemized as parts plus labor, where the cost for parts is the original cost plus a markup, and the labor rate is $80 per hour. A customer brought in his TV and paid the $50 diagnostic fee. IFixIT determined a new power cord was needed. To fix it, IFixIT purchases the part from its suppliers at $42 and pays $75 in direct labor for 3 hours at $25 per hour. Overhead is applied equal to the direct labor cost of $75. The customer is charged $310, consisting of $70 for the part and 3 hours of labor at a rate of $80 per hour. IFixIT records the journal entries shown: Ethical Considerations Subcontractor Misrepresentation of Costs of Jobs Used to Overbill Clients Construction is a typical industry where job order costing and related accounting misstatements can be used to commit fraud. A construction subcontractor might overstate the units of production accomplished, the units of labor, or the equipment actually used. 2 This occurs most commonly with subcontractor fraud, where the subcontractor does not perform the work but bills for it anyway. 2 Jim Schmid and Todd F. Taggart, “The Most Common Types of Construction Fraud,” Construction Business Owner , November 2, 2011, http://www.constructionbusinessowner.com/insurance/risk-management/most-common-types-construction-fraud. Another complicating issue is that many subcontractors are disadvantaged business enterprises that are required by law to be included in governmental construction contracts. In Chicago, for example, McHugh Construction paid $12 million in fines to settle the claims that its disadvantaged business enterprise subcontractor did not perform work. 3 The subcontractor received a prison sentence, and a related party was put on probation. An accountant had to prepare the invoices that allowed this common type of scheme to operate. 3 Kim Slowey, “Chicago Subcontractor Sentenced to 1-year Prison Term for DBE Fraud Scheme,” Construction Dive , March 20, 2017, https://www.constructiondive.com/news/chicago-subcontractor-sentenced-to-1-year-prison-term-for-dbe-fraud-scheme/438441/.
business_law_i_essentials
Chapter Outline 8.1 The Nature and Origins of Sales Contracts 8.2 Warranties and Sales Contracts Introduction Learning Outcome Recognize nuances of contracts pertaining to sales.
[ { "answer": { "ans_choice": 2, "ans_text": "Cumulative." }, "bloom": null, "hl_context": "<hl> Principal : the validity does not depend upon the existence of other contracts <hl> <hl> Bilateral : both parties in the contract are bound to fulfill reciprocal obligations toward each other <hl> <hl> Consensual : they are perfected by mere consent without the need for any additional acts <hl> <hl> It has generally been established that there are six main features of sales contracts . <hl> Sales contracts are :", "hl_sentences": "Principal : the validity does not depend upon the existence of other contracts Bilateral : both parties in the contract are bound to fulfill reciprocal obligations toward each other Consensual : they are perfected by mere consent without the need for any additional acts It has generally been established that there are six main features of sales contracts .", "question": { "cloze_format": "The elements of a contract do not include ___ ", "normal_format": "Which of the following element is NOT an element of a contract?", "question_choices": [ "Consensual.", "Bilateral.", "Cumulative.", "Principal." ], "question_id": "fs-212323156", "question_text": "All of the following are features of sales contracts except:" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 1, "ans_text": "b" }, "bloom": null, "hl_context": "<hl> Only in very limited circumstances ( such as in the buying and selling of stocks ) does federal law govern sales contracts . <hl> Until the 1950s , there were two main sources of law for sales contracts : state common law and state statutory law . Thus , the laws governing sales contracts differed from state to state . As interstate commercial activity grew in importance , there was a need for a uniform law for sales transactions that would harmonize rules across the states . <hl> Therefore , in 1952 , the Uniform Commercial Code ( UCC ) was created to govern business transactions . <hl> All 50 states have adopted the Code , but each has the power to modify it , in line with the wishes of the state legislature .", "hl_sentences": "Only in very limited circumstances ( such as in the buying and selling of stocks ) does federal law govern sales contracts . Therefore , in 1952 , the Uniform Commercial Code ( UCC ) was created to govern business transactions .", "question": { "cloze_format": "The burden of proof in a criminal case is ___ .", "normal_format": "What is a criminal case that is the burden of proof?", "question_choices": [ "Common Law.", "The Uniform Commercial Code.", "Statutory Law.", "Federal Law." ], "question_id": "fs-21232315", "question_text": "What source of law governs sales contracts?" }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 3, "ans_text": "Product defect." }, "bloom": null, "hl_context": "<hl> Inadequate warning against the dangers involved in using the good . <hl> <hl> Inadequate instructions on the use of the good <hl> <hl> Manufacturing defects <hl> <hl> Design defects <hl> <hl> If the buyer believes that there has been a breach of the implied warranty of merchantability , it is their responsibility to demonstrate that the good was defective , that this defect made the good not fit for purpose , and that this defect caused the plaintiff harm . <hl> <hl> Typical examples of defects are : <hl>", "hl_sentences": "Inadequate warning against the dangers involved in using the good . Inadequate instructions on the use of the good Manufacturing defects Design defects If the buyer believes that there has been a breach of the implied warranty of merchantability , it is their responsibility to demonstrate that the good was defective , that this defect made the good not fit for purpose , and that this defect caused the plaintiff harm . Typical examples of defects are :", "question": { "cloze_format": "___ is most likely to be classified as a necessity for which a minor will be held liable on a contract.", "normal_format": "Which of the following is most likely to be classified as a necessity for which a minor will be held liable on a contract?", "question_choices": [ "Design defect.", "Manufacturing defect.", "Inadequate instructions.", "Product defect." ], "question_id": "fs-2123231560", "question_text": "Examples of a defect in a breach of the implied warranty of merchantability, include all of the following except:" }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 3, "ans_text": "d" }, "bloom": null, "hl_context": "<hl> Sue <hl> <hl> Obtain cover <hl> <hl> Cancel the contract <hl> <hl> Remedies to Buyers under the UCC <hl>", "hl_sentences": "Sue Obtain cover Cancel the contract Remedies to Buyers under the UCC", "question": { "cloze_format": "To ___ is a possible remedy to buyers under the UCC.", "normal_format": "Which of the followings are possible remedies to buyers under the UCC?", "question_choices": [ "Cancel the contract.", "Obtain Cover.", "Sue.", "All of the above." ], "question_id": "fs-2123253156", "question_text": "The following are possible remedies to buyers under the UCC:" }, "references_are_paraphrase": null } ]
8
8.1 The Nature and Origins of Sales Contracts Features of Sales Contracts Commercial enterprises that engage in buying and selling practices need to be aware of the features and nature of sales contracts . A contract of sale is a specific type of contract in which one party is obligated to deliver and transfer ownership of a good to a second party, who in turn is obligated to pay for the good in money, or its equivalent. The party who is obligated to deliver the good is known as the vendor or seller. The party who is obligated to pay for the good is known as the vendee or buyer. It has generally been established that there are six main features of sales contracts. Sales contracts are: Consensual : they are perfected by mere consent without the need for any additional acts Bilateral : both parties in the contract are bound to fulfill reciprocal obligations toward each other Onerous : the good sold is conveyed in consideration of the price, and the price paid is conveyed in consideration of the good Commutative : the good sold is considered to be the equivalent of the price, and vice versa Nominate : this type of contract has a special designation (i.e., sale) Principal : the validity does not depend upon the existence of other contracts Sources of Law for Sales Contracts Only in very limited circumstances (such as in the buying and selling of stocks) does federal law govern sales contracts. Until the 1950s, there were two main sources of law for sales contracts: state common law and state statutory law. Thus, the laws governing sales contracts differed from state to state. As interstate commercial activity grew in importance, there was a need for a uniform law for sales transactions that would harmonize rules across the states. Therefore, in 1952, the Uniform Commercial Code ( UCC )was created to govern business transactions. All 50 states have adopted the Code, but each has the power to modify it, in line with the wishes of the state legislature. The Uniform Commercial Code The UCC categorizes items that can be bought or sold into three types: Goods are defined in Section 2-105 of the UCC as tangible items “which are movable at the time of identification to the contract for sale.” Therefore, the primary features of goods are that they are movable and tangible. Refrigerators, paper, and furniture are all examples of goods. Services are items that are movable but not tangible. Accounting is an example of a service. Realty describes non-good items that are tangible but not movable. Under this definition, commercial and residential property are classed as realty. These definitions have created some grey areas that have been clarified by the courts in their interpretation of the UCC. In the 2008 case Crown Castle Inc. et al. v. Fred Nudd Corporation et al. , a case in which the telecommunications company Crown Castle sued a cell phone tower installation firm for the construction of faulty towers, the courts had to determine whether cell phone towers (monopoles) should be classified as movable (and hence goods) or non-movable (and therefore realty). Ultimately, it was determined that monopoles are goods. Items that are attached to realty (e.g. a counter or a bar) and that are used for business activities are described as trade fixtures and treated as goods. Software licenses are not tangible, but they are also not movable, and have been treated in different ways: as goods, a mixed sale (a tangible item tied to an intangible item), and pure services. Items such as soil and clay may be treated as goods even if they are part of immovable land because they can be extracted and moved. Crops that are sold while they are still growing on the land are also considered to be goods even though they are technically immovable while growing. Article 2 of the UCC specifically pertains to sales contracts of goods. It defines a sale as a transaction that involves “the passing of title from the seller to the buyer for a price.” However, merchants are classified as a separate entity under the terms of the UCC. This distinction is important because the Code contains provisions that specifically apply to merchants and place greater duties on merchants to protect private citizens. There are four ways in which an entity can be classified as a merchant: Classification Examples An agent who regularly sells goods as part of his or her business or trade A seller on an online auction site An individual who employs other people to sell goods The owner of a clothing store A person who works for a person who sells goods An employee at a grocery retailer Any entity who self-identifies as a merchant An individual who describes himself or herself as a merchant in corporate documents Table 8.1 Formation of Sales Contracts under the UCC Sales contracts require most of the same components as general contracts, but the UCC includes some provisions that specifically pertain to the creation of sales contracts. First, the UCC includes a new category of offer . Basic contract law states that for an offer to be valid, it has to have “definiteness of terms.” In the UCC, most of that particular rule is modified for greater flexibility. If the parties have “open” (in other words, “not definite”) terms, the UCC addresses the situation with an overlay of “reasonableness”—for example, if no time for performance is designated, the performance must occur within a “reasonable” time. As a result, the following terms are legally allowed to be “open,” and there is a “default” provision that will apply under the UCC: Open Term Default Applicable UCC Provision Price If price is not named, the default is “reasonable price.” UCC 2-305(1) Payment If payment is not named, default is “due at the time and place at which the buyer is to receive the goods.” UCC 2-310(a) Delivery If delivery is not named, the default is “buyer normally takes delivery at the seller’s place of business.” UCC 2-308(a) Duration of an Ongoing Contract If duration of an ongoing contract is not named, the default is “buyer normally takes delivery at the seller’s place of business.” UCC 2-308(a) Table 8.2 The only term that really cannot be left open is the quantity term. The court is not going to second-guess a quantity if the parties don’t set one in the contract—for example, why would the court arbitrarily want to force the parties to buy and sell 15,000 widgets if a quantity wasn’t specified? There are two exceptions to this rule: requirements contracts (“as much as I need”) and output contracts (“as much as you can produce”). Even though these ideas are illusory , they’re generally allowed in the commercial setting with good-faith limitations under UCC 2-306. Sometimes, however, the courts will not allow purported “requirements” contracts. In one case, a court ruled that the contract was an unenforceable illusory contract instead of an enforceable requirements contract, even though it was a contract for the sale of goods (“as much as I need”). The reason for this ruling was that it did not appear that the buyer had any real intention of going through with any purchase. Under Section 2-205 of the UCC, offers made by merchants are considered to be firm offers if the offers are made in writing and explicitly state that there is a three-month irrevocability period. A three-month irrevocability period is assumed if no mention is made with the offer. Acceptance of the offer can be made in any reasonable manner, but the mirror-image rule does not apply under the UCC. This means that if the terms of the acceptance do not mirror those of the offer, the acceptance is treated as a counteroffer and no legal contract is formed. Sale of goods contracts must be in writing if the value of the goods is $500 or more. Modifications to the contract must be made in good faith, and new consideration is not required. A contract provision, or the entire contract itself, can be considered to be unconscionable if its terms are unfair or unreasonable. If a court deems this to be the case, the contract, or certain provisions of it, may be unenforceable. Title Title means ownership of a good. When the sale is completed, an agent must pass the title for the good to the buyer. There are three types of titles: Good title describes a title that is obtained from an individual who owns the goods free and clear. Void title occurs when the title is passed to the buyer from a person who does not legitimately own the title. An important point is that good faith is irrelevant when a void title is acquired. For example, a person who unknowingly purchased stolen goods has a void title. An exception occurs when an owner entrusts goods to a merchant who ordinarily deals in those goods, and then that merchant sells the goods to a good-faith buyer. In this case, the buyer acquires a good title. For example, if a motorcycle owner takes the motorcycle to a vehicle repair shop and the motorcycle is accidentally sold, the buyer acquires the title. Voidable title occurs when the contract would have been good, but certain circumstances make it voidable. For example, if the buyer was deceitful about his or her true identity, the buyer is a minor, or the buyer wrote a bad check in the sale, then the title is deemed voidable. Issues Associated with Title Imagine the following scenario: A café purchases a new coffee machine from a supplier. However, when the supplier tries to deliver the equipment to the café, it is involved in an accident and the coffee machine is destroyed. A question emerging from this scenario is this: Is the supplier legally obligated to replace the machine? Asked differently: Who holds the good title in this scenario? Prior to the introduction of the Uniform Common Code, the loss would have fallen on the owner of the café, since he or she paid for the coffee machine prior to taking possession of it. Under the UCC, however, as long as the supplier is considered a merchant, the risk of loss remains with the merchant until the buyer takes possession of the good. Given problems like the one described above, the UCC separately considers four specific issues relating to titles: Ownership . Under consideration is the question of when the title transfers from vendor to vendee, and hence when ownership is said to occur. The concept of encumbrance considers when the vendee is granted an interest in the good such that the good can be used as collateral for a debt. The UCC considers when the risk of loss attaches and what the responsibilities of the buyer and seller are to each other, should a loss occur. Insurable interest is the right to insure the goods against exposure to risk of loss or damage The UCC allows four scenarios for sales contracts: simple delivery contracts, common-carrier delivery contracts, goods-in-bailment contracts, and conditional sales contracts. Each type involves the title, risk of loss, and insurable interest passing at different times. A simple delivery contract occurs when the goods are transferred from the buyer to the seller at the time of the sale or later, e.g., if the goods are delivered. Title transfers when the contract is executed, insurable interest passes at the same time, and risk of loss transfers when the buyer takes possession, unless the seller is not a merchant. In the latter case, under the rule of tender of delivery , risk remains with the buyer. A common-carrier delivery contract occurs when a common carrier, who is an independent contractor rather than an agent of the seller (e.g., a trucking line), delivers the goods. The UCC further categorizes these types of contracts into shipment contracts and destination contracts: A shipment contract occurs when it is the responsibility of the seller to make the shipping arrangements and to transfer the goods to the common carrier. Under this contract, title passes to the buyer at the time of shipment, so the buyer bears the risk of loss, even when he or she has not taken possession of the goods. A destination contract occurs when the seller is required to deliver the goods to a location that is stipulated in the contract. Under this contract, title transfers when the goods are delivered, but the seller bears the risk of loss until that time. A goods-in-bailment contract occurs when the goods are stored under the control of a third party, such as in a warehouse or on a ship. Transfer of title and risk of loss depends on whether the seller has a document indicating ownership of the goods and whether that document is negotiable or non-negotiable. A negotiable document contains the words, “deliver to the order of [seller].” As soon as that document is endorsed to the buyer, both title and risk pass to the buyer. A non-negotiable document lacks those words. Under these circumstances, title passes with the endorsement of the document, but risk of loss does not pass until the custodian of the goods is notified of the title. If a document of title is completely absent, title passes at the same time as the execution of the contract, but risk does not pass until the custodian is notified of, and acknowledges, the transaction. Insurable interest is created when either the buyer or seller has the title, risk of loss, or an economic interest in the goods. Finally, a conditional sales contract is a contract that occurs when the sale is dependent on approval. For example, a sale-or-return agreement occurs when both parties agree that the buyer can return the goods at a later date. Insurable interest is created once the goods are identified in the contract. Title and risk of loss depend on whether the goods are delivered by the common carrier, the seller, or in bailment, as described above. The International Sale of Goods With globalization, there has been a significant expansion of commercial transactions undertaken across international borders. The United Nations Convention on Contracts for the International Sale of Goods , or the CISG, is the main legal structure offered for the governance of international commercial transactions. The CISG broadly covers the same topics as the UCC, but it preempts the UCC if there is a problem with an international sale. 8.2 Warranties and Sales Contracts Warranties A warranty is a guarantee on the good that comes as part of the sales contract, but contract law treats warranties as an additional form of contract that binds the selling party to undertake a certain action. Typically, the selling party has an obligation to provide a product that achieves a specified task, or to deliver a service that meets certain minimal standards. Warranties are offered for a range of different goods and services, from manufactured goods to real estate to plumbing services. The warranty assures the buyer that the good or service is free from defects, and it is a legally binding commitment. In the event that the product or service fails to meet the standards set out in the warranty, then the contract provides a specific remedy, such as a replacement or repair. According to UCC 1-203, the performance and execution of all contracts must be undertaken in good faith. Good faith means honesty in fact and the observance of reasonable commercial standards of fair dealing. If the parties in the contract are merchants, the UCC also requires that the contract be undertaken in accordance with commercial reasonableness. This requirement means that the transaction should be undertaken in a sensible and prudent way. Express and Implied Warranties Warranties can be express, implied, or both. Both express and implied warranties provide legal relief for the purchaser in the event of a breach of contract. An express warranty is one in which the seller explicitly guarantees the quality of the good or service sold. Typically, the vendor provides a statement, or other binding document, as part of the sales contract. What this means in practice is that the buyer has engaged in the contract on the reasonable assumption that the quality, nature, character, purpose, performance, state, use, or capacity of the goods or services are the same as those stated by the seller. Therefore, the sales contract is based, in part, on the understanding that the goods or services being supplied by the seller will conform to the description, or any sample, that has been provided. There are myriad ways in which the seller can make statements as to the characteristics of the goods. Here are a few examples of express warranties: “Wrinkle-free shirt” “Lifetime guarantee” “Made in the USA” “This orange juice is not from concentrate” “24k gold” There is not a specific way that words must be formed to make an express warranty valid. Importantly, the sales contract does not need to explicitly state that a warranty is being intended. It is enough that the seller asserts facts about the goods that then become part of the contract between the parties. However, the courts do apply a reasonableness test of reliance upon warranties. Puffery, or language used to bolster sales, is lawful, and the consumer is required to apply reason when evaluating such statements. For example, buyers are expected to use reason when judging seller claims such as “this sandwich is the best in the world.” Obvious sales talk cannot ordinarily be treated as a legally binding warranty. A breach of the warranty occurs when the express warranty has been found to be false. In such circumstances, the warrantor is legally liable just as though the truth of the warranty had been guaranteed. The courts do not accept as a defense: Seller claims the warranty was true. Seller claims due care was exercised in the production or handling of the product. Seller claims there is not any reason to believe that the warranty was false. Implied Warranties In certain circumstances where no express warranty was made, the law implies a warranty. This statement means that the warranty automatically arises from the fact that a sale was made. With regard to implied warranties, the law distinguishes between casual sellers and merchant sellers, with the latter held to a higher standard, given that they are in the business of buying or selling the good or service rendered. For example, unless otherwise agreed, goods sold by merchants carry an implied warranty against claims by any third party by way of trademark infringement, patent infringement, or any other intellectual property law infringement. This type of warranty is known as the warranty against infringement. Another implied warranty provided by merchant sellers is the warranty of fitness for normal use , which means that the goods must be fit for the ordinary purposes for which they are sold. It is important to note that if express warranties are made, this does not preclude implied warranties. If an express warranty is made, it should be consistent with implied warranties, and can be treated as cumulative, if such a construction is reasonable. If the express and implied warranties cannot be construed as consistent and cumulative , the express warranty generally prevails over the implied warranty, except in the case of the implied warranty of merchantability , or fitness for purpose. Breaches of Warranty If the buyer believes that there has been a breach of the implied warranty of merchantability, it is their responsibility to demonstrate that the good was defective, that this defect made the good not fit for purpose, and that this defect caused the plaintiff harm. Typical examples of defects are: Design defects Manufacturing defects Inadequate instructions on the use of the good Inadequate warning against the dangers involved in using the good. Specific Examples of Goods Under the Warranty of Merchantability Type Description Second-hand goods The UCC treats warranties arising for used goods in the same way as warranties arising for new goods, but second-hand products tend to be held to a lower standard on the warranty of merchantability. Buyer-designed goods The same warranties arise for mass manufactured goods as for goods that have been specified or made to order for the buyer. However, in this case, no warranty of fitness for purpose can arise since the buyer is using his or her own decisions, skill, and judgment when making the purchase. Food and drink The sale of food or drink carries the implied warranty of being fit for human consumption. Table 8.3 The buyer might intend to use the goods purchased for a different purpose than that for which it was sold. In this case, the implied warranty holds only if the buyer relies on the seller’s skill or judgment to select the product, the buyer informs the seller at the time of purchase of his or her intention for the use of the good, and the buyer relies on the seller’s judgment and skill in making the final choice. If the seller is not made aware of the buyer’s true intention, or does not offer his or her skill and judgment in aiding the sale, then warranty of fitness for a particular purpose does not arise. For this reason, it is common for vendors to include provisions in the average terms and conditions of sale with regard to the true and intended purpose of use. Warranty of Title By the mere act of selling, the vendor implies a warranty that the title is good and that the transfer of title is lawful. In addition, the act of the sale creates a warranty that the goods shall be delivered free from any lien of which the buyer was unaware. In some circumstances, the warranty of title can be excluded from the contract documents. For instance, when the seller makes the sale in a representative capacity (e.g. as an executor of an estate), then a warranty of title will not arise. Remedies to Buyers under the UCC Remedy Description Cancel the contract The UCC allows buyers to cancel the contract for nonconforming goods and to seek remedies that give them the benefit of the bargain. Obtain cover Buyers are allowed to substitute goods for those due under the sales contract. However, substitutes must be reasonable, acquired without delay, and obtained in good faith. Obtain specific performance If the goods are unique or a legal remedy is inadequate, the seller may be required to deliver the goods as identified in the contract. Sue Buyers are entitled to consequential and incidental damages if there is a breach of contract. They may also be able to obtain liquidated damages (damages before the breach occurs) or punitive damages. Table 8.4
introduction_to_sociology
Learning Objectives 18.1 Economic Systems Understand types of economic systems and their historical development Describe capitalism and socialism both in theory and in practice Discussion how functionalists, conflict theorists, and symbolic interactionists view the economy and work 18.2 Globalization and the Economy Define globalization and describe its manifestation in modern society Discuss the pros and cons of globalization from an economic standpoint 18.3 Work in the United States Describe the current United States' workforce and the trend of polarization Explain how women and immigrants have impacted the modern American workforce Understand the basic elements of poverty in the US today Introduction to Work and the Economy Ever since the first people traded one item for another, there has been some form of economy in the world. It is how people optimize what they have to meet their wants and needs. Economy refers to the social institution through which a society’s resources (goods and services) are managed. Goods , or commodities , are the physical objects we find, grow, or make in order to meet our needs and the needs of others. Goods can meet essential needs, such as a place to live, clothing, and food, or they can be luxuries—those things we do not need to live but want anyway. In contrast to these objects , services are activities that benefit people. Examples of services include food preparation and delivery, health care, education, and entertainment. These services provide some of the resources that help to maintain and improve a society. The food industry helps ensure that all of a society’s members have access to sustenance. Health care and education systems care for those in need, help foster longevity, and equip people to become productive members of society. Economy is one of human society’s earliest social structures. Our earliest forms of writing (such as Sumerian clay tablets) were developed to record transactions, payments, and debts between merchants. As societies grow and change, so do their economies. The economy of a small farming community is very different from the economy of a large nation with advanced technology. In this chapter, we will examine different types of economic systems and how they have functioned in various societies.
[ { "answer": { "ans_choice": 1, "ans_text": "Corn" }, "bloom": null, "hl_context": "<hl> Globalization has also led to the development of global commodity chains , where internationally integrated economic links connect workers and corporations for the purpose of manufacture and marketing ( Plahe 2005 ) . <hl> <hl> For example , in maquiladoras , mostly found in northern Mexico , workers may sew imported precut pieces of fabric into garments . <hl> Globalization also brings an international division of labor , in which comparatively wealthy workers from core nations compete with the low-wage labor pool of peripheral and semi-peripheral nations . This can lead to a sense of xenophobia , which is an illogical fear and even hatred of foreigners and foreign goods . Corporations trying to maximize their profits in the United States are conscious of this risk and attempt to “ Americanize ” their products , selling shirts printed with U . S . flags that were nevertheless made in Mexico . Ever since the first people traded one item for another , there has been some form of economy in the world . It is how people optimize what they have to meet their wants and needs . Economy refers to the social institution through which a society ’ s resources ( goods and services ) are managed . <hl> Goods , or commodities , are the physical objects we find , grow , or make in order to meet our needs and the needs of others . <hl> <hl> Goods can meet essential needs , such as a place to live , clothing , and food , or they can be luxuries — those things we do not need to live but want anyway . <hl> In contrast to these objects , services are activities that benefit people . Examples of services include food preparation and delivery , health care , education , and entertainment . These services provide some of the resources that help to maintain and improve a society . The food industry helps ensure that all of a society ’ s members have access to sustenance . Health care and education systems care for those in need , help foster longevity , and equip people to become productive members of society . Economy is one of human society ’ s earliest social structures . Our earliest forms of writing ( such as Sumerian clay tablets ) were developed to record transactions , payments , and debts between merchants . As societies grow and change , so do their economies . The economy of a small farming community is very different from the economy of a large nation with advanced technology . In this chapter , we will examine different types of economic systems and how they have functioned in various societies .", "hl_sentences": "Globalization has also led to the development of global commodity chains , where internationally integrated economic links connect workers and corporations for the purpose of manufacture and marketing ( Plahe 2005 ) . For example , in maquiladoras , mostly found in northern Mexico , workers may sew imported precut pieces of fabric into garments . Goods , or commodities , are the physical objects we find , grow , or make in order to meet our needs and the needs of others . Goods can meet essential needs , such as a place to live , clothing , and food , or they can be luxuries — those things we do not need to live but want anyway .", "question": { "cloze_format": "___ is an example of a commodity.", "normal_format": "Which of these is an example of a commodity?", "question_choices": [ "Cooking ", "Corn", "Teaching", "Writing" ], "question_id": "fs-id1887284", "question_text": "Which of these is an example of a commodity?" }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 2, "ans_text": "When people began to grow crops and domesticate animals" }, "bloom": "1", "hl_context": "The improved efficiency in food production meant that not everyone had to toil all day in the fields . As agriculture grew , new jobs emerged , along with new technologies . <hl> Excess crops needed to be stored , processed , protected , and transported . <hl> <hl> Farming equipment and irrigation systems needed to be built and maintained . <hl> <hl> Wild animals needed to be domesticated and herds shepherded . <hl> <hl> Economies begin to develop because people now had goods and services to trade . <hl> <hl> The Agricultural Revolution The first true economies arrived when people started raising crops and domesticating animals . <hl> <hl> Although there is still a great deal of disagreement among archeologists as to the exact timeline , research indicates that agriculture began independently and at different times in several places around the world . <hl> The earliest agriculture was in the Fertile Crescent in the Middle East around 11,000 – 10,000 years ago . Next were the valleys of the Indus , Yangtze , and Yellow rivers in India and China , between 10,000 and 9,000 years ago . The people living in the highlands of New Guinea developed agriculture between 9,000 and 6,000 years ago , while people were farming in Sub-Saharan Africa between 5,000 and 4,000 years ago . Agriculture developed later in the western hemisphere , arising in what would become the eastern United States , central Mexico , and northern South America between 5,000 and 3,000 years ago ( Diamond 2003 ) .", "hl_sentences": "Excess crops needed to be stored , processed , protected , and transported . Farming equipment and irrigation systems needed to be built and maintained . Wild animals needed to be domesticated and herds shepherded . Economies begin to develop because people now had goods and services to trade . The Agricultural Revolution The first true economies arrived when people started raising crops and domesticating animals . Although there is still a great deal of disagreement among archeologists as to the exact timeline , research indicates that agriculture began independently and at different times in several places around the world .", "question": { "cloze_format": "The first economies began to develop ___.", "normal_format": "When did the first economies begin to develop?", "question_choices": [ "When all of the hunter-gatherers died", "When money was invented", "When people began to grow crops and domesticate animals", "When the first cities were built" ], "question_id": "fs-id3033350", "question_text": "When did the first economies begin to develop?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 2, "ans_text": "Information" }, "bloom": "1", "hl_context": "The rapid increase in computer use in all aspects of daily life is a main reason for the transition to an information economy . Fewer people are needed to work in factories because computerized robots now handle many of the tasks . Other manufacturing jobs have been outsourced to less-developed countries as a result of the developing global economy . The growth of the internet has created industries that exist almost entirely online . Within industries , technology continues to change how goods are produced . For instance , the music and film industries used to produce physical products like CDs and DVDs for distribution . Now those goods are increasingly produced digitally and streamed or downloaded at a much lower physical manufacturing cost . <hl> Information and the wherewithal to use it creatively become commodities in a postindustrial economy . <hl> <hl> Postindustrial societies , also known as information societies , have evolved in modernized nations . <hl> <hl> One of the most valuable goods of the modern era is information . <hl> Those who have the means to produce , store , and disseminate information are leaders in this type of society .", "hl_sentences": "Information and the wherewithal to use it creatively become commodities in a postindustrial economy . Postindustrial societies , also known as information societies , have evolved in modernized nations . One of the most valuable goods of the modern era is information .", "question": { "cloze_format": "___ is/are the most important commodity in a postindustrial society.", "normal_format": "What is the most important commodity in a postindustrial society?", "question_choices": [ "Electricity", "Money", "Information", "Computers" ], "question_id": "fs-id3630714", "question_text": "What is the most important commodity in a postindustrial society?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 3, "ans_text": "Quaternary" }, "bloom": null, "hl_context": "One way scholars understand the development of different types of societies ( like agricultural , industrial , and postindustrial ) is by examining their economies in terms of four sectors : primary , secondary , tertiary , and quaternary . Each has a different focus . The primary sector extracts and produces raw materials ( like metals and crops ) . The secondary sector turns those raw materials into finished goods . The tertiary sector provides services : child care , health care , and money management . <hl> Finally , the quaternary sector produces ideas ; these include the research that leads to new technologies , the management of information , and a society ’ s highest levels of education and the arts ( Kenessey 1987 ) . <hl>", "hl_sentences": "Finally , the quaternary sector produces ideas ; these include the research that leads to new technologies , the management of information , and a society ’ s highest levels of education and the arts ( Kenessey 1987 ) .", "question": { "cloze_format": "The sector of an economy in which someone working as a software developer would be is the ___.", "normal_format": "In which sector of an economy would someone working as a software developer be?", "question_choices": [ "Primary", "Secondary", "Tertiary", "Quaternary" ], "question_id": "fs-id2912805", "question_text": "In which sector of an economy would someone working as a software developer be?" }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 2, "ans_text": "Mercantilism" }, "bloom": null, "hl_context": "Governments tried to protect their share of the markets by developing a system called mercantilism . <hl> Mercantilism is an economic policy based on accumulating silver and gold by controlling colonial and foreign markets through taxes and other charges . <hl> The resulting restrictive practices and exacting demands included monopolies , bans on certain goods , high tariffs , and exclusivity requirements . Mercantilistic governments also promoted manufacturing and , with the ability to fund technological improvements , they helped create the equipment that led to the Industrial Revolution .", "hl_sentences": "Mercantilism is an economic policy based on accumulating silver and gold by controlling colonial and foreign markets through taxes and other charges .", "question": { "cloze_format": "___ is an economic policy based on national policies of accumulating silver and gold by controlling markets with colonies and other countries through taxes and customs charges.", "normal_format": "Which is an economic policy based on national policies of accumulating silver and gold by controlling markets with colonies and other countries through taxes and customs charges?", "question_choices": [ "Capitalism ", "Communism", "Mercantilism", "Mutualism" ], "question_id": "fs-id1194699", "question_text": "Which is an economic policy based on national policies of accumulating silver and gold by controlling markets with colonies and other countries through taxes and customs charges?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 0, "ans_text": "Karl Marx" }, "bloom": "1", "hl_context": "<hl> By far the most important influential thinker on socialism was Karl Marx . <hl> Through his own writings and those with his collaborator , industrialist Friedrich Engels , Marx used a scientific analytical process to show that throughout history the resolution of class struggles caused changes in economies . He saw the relationships evolving from slave and owner , to serf and lord , to journeyman and master , to worker and owner . Neither Marx nor Engels thought socialism could be used to set up small utopian communities . Rather , they believed a socialist society would be created after workers rebelled against capitalistic owners and seized the means of production . They felt industrial capitalism was a necessary step that raised the level of production in society to a point it could progress to a socialist state ( Marx and Engels 1848 ) . These ideas formed the basis of the sociological perspective of social conflict theory .", "hl_sentences": "By far the most important influential thinker on socialism was Karl Marx .", "question": { "cloze_format": "___ was the leading theorist on the development of socialism.", "normal_format": "Who was the leading theorist on the development of socialism?", "question_choices": [ "Karl Marx", "Alex Inkeles", "Emile Durkheim", "Adam Smith" ], "question_id": "fs-id2868939", "question_text": "Who was the leading theorist on the development of socialism?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 1, "ans_text": "market" }, "bloom": "1", "hl_context": "We have seen how the economies of some capitalist countries such as the United States have features that are very similar to socialism . Some industries , particularly utilities , are either owned by the government or controlled through regulations . Public programs such as welfare , Medicare , and Social Security exist to provide public funds for private needs . <hl> We have also seen how several large communist ( or formerly communist ) countries such as Russia , China , and Vietnam have moved from state-controlled socialism with central planning to market socialism , which allows market forces to dictate prices and wages , and for some business to be privately owned . <hl> In many formerly communist countries , these changes have led to economic growth compared to the stagnation they experienced under communism ( Fidrmuc 2002 ) .", "hl_sentences": "We have also seen how several large communist ( or formerly communist ) countries such as Russia , China , and Vietnam have moved from state-controlled socialism with central planning to market socialism , which allows market forces to dictate prices and wages , and for some business to be privately owned .", "question": { "cloze_format": "The type of socialism now carried on by Russia is a form of ______ socialism.", "normal_format": "Which type of socialism is now carried on by Russia?", "question_choices": [ "centrally planned", "market", "utopian", "zero-sum" ], "question_id": "fs-id2332682", "question_text": "The type of socialism now carried on by Russia is a form of ______ socialism." }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 0, "ans_text": "secured workers’ rights" }, "bloom": "3", "hl_context": "<hl> Organized socialism never became powerful in the United States . <hl> <hl> The success of labor unions and the government in securing workers ’ rights , joined with the high standard of living enjoyed by most of the workforce , made socialism less appealing than the controlled capitalism practiced here . <hl>", "hl_sentences": "Organized socialism never became powerful in the United States . The success of labor unions and the government in securing workers ’ rights , joined with the high standard of living enjoyed by most of the workforce , made socialism less appealing than the controlled capitalism practiced here .", "question": { "cloze_format": "Among the reasons socialism never developed into a political movement in the United States was that trade unions _________.", "normal_format": "Socialism never developed into a political movement in the United States due to which activity of trade unions?", "question_choices": [ "secured workers’ rights", "guaranteed health care", "broke up monopolies", "diversified the workforce" ], "question_id": "fs-id2794430", "question_text": "Among the reasons socialism never developed into a political movement in the United States was that trade unions _________." }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 0, "ans_text": "Singapore" }, "bloom": "1", "hl_context": "Supporters of the theory point to Germany , France , and Japan — countries that rapidly rebuilt their economies after World War II . <hl> They point out how , in the 1960s and 1970s , East Asian countries like Singapore , South Korea , and Taiwan converged with countries with developed economies . <hl> <hl> They are now considered developed countries themselves . <hl>", "hl_sentences": "They point out how , in the 1960s and 1970s , East Asian countries like Singapore , South Korea , and Taiwan converged with countries with developed economies . They are now considered developed countries themselves .", "question": { "cloze_format": "The country that serves as an example of convergence is ___.", "normal_format": "Which country serves as an example of convergence?", "question_choices": [ "Singapore", "North Korea", "England", "Canada" ], "question_id": "fs-id1354839", "question_text": "Which country serves as an example of convergence?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 3, "ans_text": "Integrating child care through international trade" }, "bloom": "1", "hl_context": "<hl> Globalization refers to the process of integrating governments , cultures , and financial markets through international trade into a single “ world market . ” Often , the process begins with a single motive , such as market expansion ( on the part of a corporation ) or increased access to health care ( on the part of a nonprofit organization ) . <hl> But usually there is a snowball effect , and globalization becomes a mixed bag of economic , philanthropic , entrepreneurial , and cultural efforts . Sometimes the efforts have obvious benefits , even for those who worry about cultural colonialism , such as campaigns to bring clean-water technology to rural areas without access to safe drinking water .", "hl_sentences": "Globalization refers to the process of integrating governments , cultures , and financial markets through international trade into a single “ world market . ” Often , the process begins with a single motive , such as market expansion ( on the part of a corporation ) or increased access to health care ( on the part of a nonprofit organization ) .", "question": { "cloze_format": "___ is not an aspect of globalization.", "normal_format": "Which of the following is not an aspect of globalization?", "question_choices": [ "Integrating governments through international trade", "Integrating cultures through international trade", "Integrating finance through international trade", "Integrating child care through international trade" ], "question_id": "fs-id1165528317410", "question_text": "Which of the following is not an aspect of globalization?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 1, "ans_text": "negative impacts on the environment" }, "bloom": null, "hl_context": "<hl> Other critics oppose globalization for what they see as negative impacts on the environment and local economies . <hl> Rapid industrialization , often a key component of globalization , can lead to widespread economic damage due to the lack of regulatory environment ( Speth 2003 ) . Further , as there are often no social institutions in place to protect workers in countries where jobs are scarce , some critics state that globalization leads to weak labor movements ( Boswell and Stevis 1997 ) . Finally , critics are concerned that wealthy countries can force economically weaker nations to open their markets while protecting their own local products from competition ( Wallerstein 1974 ) . This can be particularly true of agricultural products , which are often one of the main exports of poor and developing countries ( Koroma 2007 ) . In a 2007 article for the United Nations , Koroma discusses the difficulties faced by “ least developed countries ” ( LDCs ) that seek to participate in globalization efforts . These countries typically lack the infrastructure to be flexible and nimble in their production and trade , and therefore are vulnerable to everything from unfavorable weather conditions to international price volatility . In short , rather than offering them more opportunities , the increased competition and fast pace of a globalized market can make it more challenging than ever for LDCs to move forward ( Koroma 2007 ) .", "hl_sentences": "Other critics oppose globalization for what they see as negative impacts on the environment and local economies .", "question": { "cloze_format": "One reason critics oppose globalization is ___.", "normal_format": "What is the reason critics oppose globalization?", "question_choices": [ "positive impacts on world trade", "negative impacts on the environment", "the concentration of wealth in the poorest countries", "negative impacts on political stability" ], "question_id": "fs-id1165528296258", "question_text": "One reason critics oppose globalization is:" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 3, "ans_text": "host influential philosophers" }, "bloom": null, "hl_context": "<hl> host influential media such as the BBC and Al Jazeera <hl> <hl> host headquarters of international nongovernmental organizations ( NGOs ) such as the United Nations <hl> <hl> exercise significant international political influence , such as what comes from Beijing or Berlin <hl> <hl> headquarter multinational corporations , such as Coca-Cola <hl> There are several components to the global economy and many changes that occur as countries grow more interdependent . <hl> First , there is an increasing number of global cities , which <hl> <hl> There are several forces driving globalization , including the global economy and multinational corporations that control assets , sales , production , and employment ( United Nations 1973 ) . <hl> Characteristics of multinational corporations include the following : A large share of their capital is collected from a variety of different nations , their business is conducted without regard to national borders , they concentrate wealth in the hands of core nations and already wealthy individuals , and they play a key role in the global economy .", "hl_sentences": "host influential media such as the BBC and Al Jazeera host headquarters of international nongovernmental organizations ( NGOs ) such as the United Nations exercise significant international political influence , such as what comes from Beijing or Berlin headquarter multinational corporations , such as Coca-Cola First , there is an increasing number of global cities , which There are several forces driving globalization , including the global economy and multinational corporations that control assets , sales , production , and employment ( United Nations 1973 ) .", "question": { "cloze_format": "All of the following are characteristics of global cities, except ___", "normal_format": "All of the following are characteristics of global cities, except which one?", "question_choices": [ "headquarter multinational corporations", "exercise significant international political influence", "host headquarters of international NGOs", "host influential philosophers" ], "question_id": "fs-id1165528304241", "question_text": "All of the following are characteristics of global cities, except:" }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 3, "ans_text": "They are headquartered primarily in the United States." }, "bloom": "1", "hl_context": "There are several forces driving globalization , including the global economy and multinational corporations that control assets , sales , production , and employment ( United Nations 1973 ) . <hl> Characteristics of multinational corporations include the following : A large share of their capital is collected from a variety of different nations , their business is conducted without regard to national borders , they concentrate wealth in the hands of core nations and already wealthy individuals , and they play a key role in the global economy . <hl>", "hl_sentences": "Characteristics of multinational corporations include the following : A large share of their capital is collected from a variety of different nations , their business is conducted without regard to national borders , they concentrate wealth in the hands of core nations and already wealthy individuals , and they play a key role in the global economy .", "question": { "cloze_format": "It is not a characteristic of multinational corporations that ___.", "normal_format": "Which of the following is not a characteristic of multinational corporations?", "question_choices": [ "A large share of their capital is collected from a variety of nationalities.", "Their business is conducted without regard to national borders.", "They concentrate wealth in the hands of core nations.", "They are headquartered primarily in the United States." ], "question_id": "fs-id1165528318347", "question_text": "Which of the following is not a characteristic of multinational corporations?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 2, "ans_text": "Highly skilled jobs pay better than low-skill jobs." }, "bloom": null, "hl_context": "In 2005 , before the recession arrived , immigrants made up a historic high of 14.7 percent of the workforce ( Lowell et al . 2006 ) . <hl> During the 1970s through 2000s , the United States experienced both an increase in college-educated immigrants and in immigrants who lacked a high school diploma . <hl> <hl> With this range across the spectrum , immigrants are well positioned for both the higher-paid jobs and the low-wage low-skill jobs that are predicted to grow in the next decade ( Lowell et al . <hl> 2006 ) . In the early 2000s , it certainly seemed that the United States was continuing to live up to its reputation of opportunity . But what about during the recession of 2008 , when so many jobs were lost and unemployment hovered close to 10 percent ? How did immigrant workers fare then ? The fact that some positions are highly paid while others are not is an example of the class system , an economic hierarchy in which movement ( both upward and downward ) between various rungs of the socioeconomic ladder is possible . <hl> Theoretically , at least , the class system as it is organized in the United States is an example of a meritocracy , an economic system that rewards merit – – typically in the form of skill and hard work – – with upward mobility . <hl> <hl> A theorist working in the functionalist perspective might point out that this system is designed to reward hard work , which encourages people to strive for excellence in pursuit of reward . <hl> <hl> A theorist working in the conflict perspective might counter with the thought that hard work does not guarantee success even in a meritocracy , because social capital – – the accumulation of a network of social relationships and knowledge that will provide a platform from which to achieve financial success – – in the form of connections or higher education are often required to access the high-paying jobs . <hl> Increasingly , we are realizing intelligence and hard work aren ’ t enough . If you lack knowledge of how to leverage the right names , connections , and players , you are unlikely to experience upward mobility .", "hl_sentences": "During the 1970s through 2000s , the United States experienced both an increase in college-educated immigrants and in immigrants who lacked a high school diploma . With this range across the spectrum , immigrants are well positioned for both the higher-paid jobs and the low-wage low-skill jobs that are predicted to grow in the next decade ( Lowell et al . Theoretically , at least , the class system as it is organized in the United States is an example of a meritocracy , an economic system that rewards merit – – typically in the form of skill and hard work – – with upward mobility . A theorist working in the functionalist perspective might point out that this system is designed to reward hard work , which encourages people to strive for excellence in pursuit of reward . A theorist working in the conflict perspective might counter with the thought that hard work does not guarantee success even in a meritocracy , because social capital – – the accumulation of a network of social relationships and knowledge that will provide a platform from which to achieve financial success – – in the form of connections or higher education are often required to access the high-paying jobs .", "question": { "cloze_format": "___ is evidence that the United States workforce is largely a meritocracy.", "normal_format": "Which is evidence that the United States workforce is largely a meritocracy?", "question_choices": [ "Job opportunities are increasing for highly skilled jobs.", "Job opportunities are decreasing for midlevel jobs.", "Highly skilled jobs pay better than low-skill jobs.", "Women tend to make less than men do for the same job. " ], "question_id": "fs-id1973829", "question_text": "Which is evidence that the United States workforce is largely a meritocracy?" }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 0, "ans_text": "absolutely" }, "bloom": "1", "hl_context": "<hl> Most developed countries such as the United States protect their citizens from absolute poverty by providing different levels of social services such as unemployment insurance , welfare , food stamps , and so on . <hl> <hl> They may also provide job training and retraining so that people can reenter the job market . <hl> In the past , the elderly were particularly vulnerable to falling into poverty after they stopped working ; however , pensions , retirement plans , and Social Security were designed to help prevent this . A major concern in the United States is the rising number of young people growing up in poverty . Growing up poor can cut off access to the education and services people need to move out of poverty and into stable employment . As we saw , more education was often a key to stability , and those raised in poverty are the ones least able to find well-paying work , perpetuating a cycle . There is great debate about how much support local , state , and federal governments should give to help the unemployed and underemployed . The decisions made on these issues will have a profound effect on working in the United States . When people lose their jobs during a recession or in a changing job market , it takes longer to find a new one , if they can find one at all . If they do , it is often at a much lower wage or not full time . This can force people into poverty . In the United States , we tend to have what is called relative poverty , defined as being unable to live the lifestyle of the average person in your country . <hl> This must be contrasted with the absolute poverty that can be found in underdeveloped countries , defined as being barely able , or unable , to afford basic necessities such as food ( Byrns 2011 ) . <hl>", "hl_sentences": "Most developed countries such as the United States protect their citizens from absolute poverty by providing different levels of social services such as unemployment insurance , welfare , food stamps , and so on . They may also provide job training and retraining so that people can reenter the job market . This must be contrasted with the absolute poverty that can be found in underdeveloped countries , defined as being barely able , or unable , to afford basic necessities such as food ( Byrns 2011 ) .", "question": { "cloze_format": "If someone does not earn enough money to pay for the essentials of life he or she is said to be _____ poor.", "normal_format": "If someone does not earn enough money to pay for the essentials of life he or she is said to be which type of poor?", "question_choices": [ "absolutely", "essentially", "really", "working" ], "question_id": "fs-id1973858", "question_text": "If someone does not earn enough money to pay for the essentials of life he or she is said to be _____ poor." }, "references_are_paraphrase": 0 } ]
18
18.1 Economic Systems The dominant economic systems of the modern era have been capitalism and socialism, and there have been many variations of each system across the globe. Countries have switched systems as their rulers and economic fortunes have changed. For example, Russia has been transitioning to a market-based economy since the fall of communism in that region of the world. Vietnam, where the economy was devastated by the Vietnam War, restructured to a state-run economy in response, and more recently has been moving toward a socialist-style market economy. In the past, other economic systems reflected the societies that formed them. Many of these earlier systems lasted centuries. These changes in economies raise many questions for sociologists. What are these older economic systems? How did they develop? Why did they fade away? What are the similarities and differences between older economic systems and modern ones? Economics of Agricultural, Industrial, and Postindustrial Societies Our earliest ancestors lived as hunter-gatherers. Small groups of extended families roamed from place to place looking for means to subsist. They would settle in an area for a brief time when there were abundant resources. They hunted animals for their meat and gathered wild fruits, vegetables, and cereals. They ate what they caught or gathered as soon as possible because they had no way of preserving or transporting it. Once the resources of an area ran low, the group had to move on, and everything they owned had to travel with them. Food reserves only consisted of what they could carry. Many sociologists contend that hunter-gatherers did not have a true economy because groups did not typically trade with other groups due to the scarcity of goods. The Agricultural Revolution The first true economies arrived when people started raising crops and domesticating animals. Although there is still a great deal of disagreement among archeologists as to the exact timeline, research indicates that agriculture began independently and at different times in several places around the world. The earliest agriculture was in the Fertile Crescent in the Middle East around 11,000–10,000 years ago. Next were the valleys of the Indus, Yangtze, and Yellow rivers in India and China, between 10,000 and 9,000 years ago. The people living in the highlands of New Guinea developed agriculture between 9,000 and 6,000 years ago, while people were farming in Sub-Saharan Africa between 5,000 and 4,000 years ago. Agriculture developed later in the western hemisphere, arising in what would become the eastern United States, central Mexico, and northern South America between 5,000 and 3,000 years ago (Diamond 2003). Agriculture began with the simplest of technologies—for example, a pointed stick to break up the soil—but really took off when people harnessed animals to pull an even more efficient tool for the same task: a plow. With this new technology, one family could grow enough crops not only to feed themselves but others as well. Knowing there would be abundant food each year as long as crops were tended led people to abandon the nomadic life of hunter-gatherers and settle down to farm. The improved efficiency in food production meant that not everyone had to toil all day in the fields. As agriculture grew, new jobs emerged, along with new technologies. Excess crops needed to be stored, processed, protected, and transported. Farming equipment and irrigation systems needed to be built and maintained. Wild animals needed to be domesticated and herds shepherded. Economies begin to develop because people now had goods and services to trade. As more people specialized in nonfarming jobs, villages grew into towns and then into cities. Urban areas created the need for administrators and public servants. Disputes over ownership, payments, debts, compensation for damages, and the like led to the need for laws and courts—and the judges, clerks, lawyers, and police who administered and enforced those laws. At first, most goods and services were traded as gifts or through bartering between small social groups (Mauss 1922). Exchanging one form of goods or services for another was known as bartering . This system only works when one person happens to have something the other person needs at the same time. To solve this problem, people developed the idea of a means of exchange that could be used at any time: that is, money. Money refers to an object that a society agrees to assign a value to so it can be exchanged for payment. In early economies, money was often objects like cowry shells, rice, barley, or even rum. Precious metals quickly became the preferred means of exchange in many cultures because of their durability and portability. The first coins were minted in Lydia in what is now Turkey around 650–600 B.C.E. (Goldsborough 2010). Early legal codes established the value of money and the rates of exchange for various commodities. They also established the rules for inheritance, fines as penalties for crimes, and how property was to be divided and taxed (Horne 1915). A symbolic interactionist would note that bartering and money are systems of symbolic exchange. Monetary objects took on a symbolic meaning, one that carries into our modern-day use of checks and debit cards. The Lady Who Lives without Money Imagine having no money. If you wanted some french fries, needed a new pair of shoes, or were due to get an oil change for your car, how would you get those goods and services? This isn’t just a theoretical question. Think about it. What do those on the outskirts of society do in these situations? Think of someone escaping domestic abuse who gave up everything and has no resources. Or an immigrant who wants to build a new life but who had to leave another life behind to find that opportunity. Or a homeless person who simply wants a meal to eat. This last example, homelessness, is what caused Heidemarie Schwermer to give up money. A divorced high school teacher in Germany, Schwermer’s life took a turn when she relocated her children to a rural town with a significant homeless population. She began to question what serves as currency in a society and decided to try something new. Schwermer founded a business called Gib und Nimm —in English, “give and take.” It operated on a moneyless basis and strived to facilitate people swapping goods and services for other goods and services—no cash allowed (Schwermer 2007). What began as a short experiment has become a new way of life. Schwermer says the change has helped her focus on people’s inner value instead of their outward wealth. It has also led to two books telling her story (she’s donated all proceeds to charity) and, most importantly, a richness in her life she was unable to attain with money. How might our three sociological perspectives view her actions? What would most interest them about her nonconventional ways? Would a functionalist consider her aberration of norms a social dysfunction that upsets the normal balance? How would a conflict theorist place her in the social hierarchy? What might a symbolic interactionist make of her choice not to use money—such an important symbol in the modern world? What do you make of Gib und Nimm ? As city-states grew into countries and countries grew into empires, their economies grew as well. When large empires broke up, their economies broke up too. The governments of newly formed nations sought to protect and increase their markets. They financed voyages of discovery to find new markets and resources all over the world, ushering in a rapid progression of economic development. Colonies were established to secure these markets, and wars were financed to take over territory. These ventures were funded in part by raising capital from investors who were paid back from the goods obtained. Governments and private citizens also set up large trading companies that financed their enterprises around the world by selling stocks and bonds. Governments tried to protect their share of the markets by developing a system called mercantilism. Mercantilism is an economic policy based on accumulating silver and gold by controlling colonial and foreign markets through taxes and other charges. The resulting restrictive practices and exacting demands included monopolies, bans on certain goods, high tariffs, and exclusivity requirements. Mercantilistic governments also promoted manufacturing and, with the ability to fund technological improvements, they helped create the equipment that led to the Industrial Revolution. The Industrial Revolution Up until the end of the 18th century, most manufacturing was done using manual labor. This changed as research led to machines that could be used to manufacture goods. A small number of innovations led to a large number of changes in the British economy. In the textile industries, the spinning of cotton, worsted yarn, and flax could be done more quickly and less expensively using new machines with names like the Spinning Jenny and the Spinning Mule (Bond 2003). Another important innovation was made in the production of iron: Coke from coal could now be used in all stages of smelting rather than charcoal from wood, dramatically lowering the cost of iron production while increasing availability (Bond 2003). James Watt ushered in what many scholars recognize as the greatest change, revolutionizing transportation and, thereby, the entire production of goods with his improved steam engine. As people moved to cities to fill factory jobs, factory production also changed. Workers did their jobs in assembly lines and were trained to complete only one or two steps in the manufacturing process. These advances meant that more finished goods could be manufactured with more efficiency and speed than ever before. The Industrial Revolution also changed agricultural practices. Until that time, many people practiced subsistence farming in which they produced only enough to feed themselves and pay their taxes. New technology introduced gasoline-powered farm tools such as tractors, seed drills, threshers, and combine harvesters. Farmers were encouraged to plant large fields of a single crop to maximize profits. With improved transportation and the invention of refrigeration, produce could be shipped safely all over the world. The Industrial Revolution modernized the world. With growing resources came growing societies and economies. Between 1800 and 2000, the world’s population grew sixfold, while per capita income saw a tenfold jump (Maddison 2003). While many people's lives were improving, the Industrial Revolution also birthed many societal problems. There were inequalities in the system. Owners amassed vast fortunes while laborers, including young children, toiled for long hours in unsafe conditions. Workers’ rights, wage protection, and safe work environments are issues that arose during this period and remain concerns today. Postindustrial Societies and the Information Age Postindustrial societies, also known as information societies, have evolved in modernized nations. One of the most valuable goods of the modern era is information. Those who have the means to produce, store, and disseminate information are leaders in this type of society. One way scholars understand the development of different types of societies (like agricultural, industrial, and postindustrial) is by examining their economies in terms of four sectors: primary, secondary, tertiary, and quaternary. Each has a different focus. The primary sector extracts and produces raw materials (like metals and crops). The secondary sector turns those raw materials into finished goods. The tertiary sector provides services: child care, health care, and money management. Finally, the quaternary sector produces ideas; these include the research that leads to new technologies, the management of information, and a society’s highest levels of education and the arts (Kenessey 1987). In underdeveloped countries, the majority of the people work in the primary sector. As economies develop, more and more people are employed in the secondary sector. In well-developed economies, such as those in the United States, Japan, and Western Europe, the majority of the workforce is employed in service industries. In the United States, for example, almost 80 percent of the workforce is employed in the tertiary sector (U.S. Bureau of Labor Statistics 2011). The rapid increase in computer use in all aspects of daily life is a main reason for the transition to an information economy. Fewer people are needed to work in factories because computerized robots now handle many of the tasks. Other manufacturing jobs have been outsourced to less-developed countries as a result of the developing global economy. The growth of the internet has created industries that exist almost entirely online. Within industries, technology continues to change how goods are produced. For instance, the music and film industries used to produce physical products like CDs and DVDs for distribution. Now those goods are increasingly produced digitally and streamed or downloaded at a much lower physical manufacturing cost. Information and the wherewithal to use it creatively become commodities in a postindustrial economy. Capitalism Scholars don’t always agree on a single definition of capitalism. For our purposes, we will define capitalism as an economic system in which there is private ownership (as opposed to state ownership) and where there is an impetus to produce profit, and thereby wealth. This is the type of economy in place in the United States today. Under capitalism, people invest capital (money or property invested in a business venture) in a business to produce a product or service that can be sold in a market to consumers. The investors in the company are generally entitled to a share of any profit made on sales after the costs of production and distribution are taken out. These investors often reinvest their profits to improve and expand the business or acquire new ones. To illustrate how this works, consider this example. Sarah, Antonio, and Chris each invest $250,000 into a start-up company offering an innovative baby product. When the company nets $1 million in profits its first year, a portion of that profit goes back to Sarah, Antonio, and Chris as a return on their investment. Sarah reinvests with the same company to fund the development of a second product line, Antonio uses his return to help another start-up in the technology sector, and Chris buys a small yacht for vacations. The goal for all parties is to maximize profits. To provide their product or service, owners hire workers, to whom they pay wages. The cost of raw materials, the retail price they charge consumers, and the amount they pay in wages are determined through the law of supply and demand and by competition. When demand exceeds supply, prices tend to rise. When supply exceeds demand, prices tend to fall. When multiple businesses market similar products and services to the same buyers, there is competition. Competition can be good for consumers because it can lead to lower prices and higher quality as businesses try to get consumers to buy from them rather than from their competitors. Wages tend to be set in a similar way. People who have talents, skills, education, or training that is in short supply and is needed by businesses tend to earn more than people without comparable skills. Competition in the workforce helps determine how much people will be paid. In times when many people are unemployed and jobs are scarce, people are often willing to accept less than they would when their services are in high demand. In this scenario, businesses are able to maintain or increase profits by not paying increasing wages. Capitalism in Practice As capitalists began to dominate the economies of many countries during the Industrial Revolution, the rapid growth of businesses and their tremendous profitability gave some owners the capital they needed to create enormous corporations that could monopolize an entire industry. Many companies controlled all aspects of the production cycle for their industry, from the raw materials to the production to the stores in which they were sold. These companies were able to use their wealth to buy out or stifle any competition. In the United States, the predatory tactics used by these large monopolies caused the government to take action. Starting in the late 1800s, the government passed a series of laws that broke up monopolies and regulated how key industries—such as transportation, steel production, and oil and gas exploration and refining—could conduct business. The United States is considered a capitalist country. However, the U.S. government has a great deal of influence on private companies through the laws it passes and the regulations enforced by government agencies. Through taxes, regulations on wages, guidelines to protect worker safety and the environment, plus financial rules for banks and investment firms, the government exerts a certain amount of control over how all companies do business. State and federal governments also own, operate, or control large parts of certain industries, such as the post office, schools, hospitals, highways and railroads, and many water, sewer, and power utilities. Debate over the extent to which the government should be involved in the economy remains an issue of contention today. Some criticize such involvements as socialism (a type of state-run economy), while others believe intervention is necessary to protect the rights of workers and the well-being of the general population. Socialism Socialism is an economic system in which there is government ownership (often referred to as “state run”) of goods and their production, with an impetus to share work and wealth equally among the members of a society. Under socialism, everything that people produce, including services, is considered a social product. Everyone who contributes to the production of a good or to providing a service is entitled to a share in any benefits that come from its sale or use. To make sure all members of society get their fair share, government must be able to control property, production, and distribution. The focus in socialism is on benefitting society, whereas capitalism seeks to benefit the individual. Socialists claim that a capitalistic economy leads to inequality, with unfair distribution of wealth and individuals who use their power at the expense of society. Socialism strives, ideally, to control the economy to avoid the problems inherent in capitalism. Within socialism, there are diverging views on the extent to which the economy should be controlled. One extreme believes all but the most personal items are public property. Other socialists believe only essential services such as health care, education, and utilities (electrical power, telecommunications, and sewage) need direct control. Under this form of socialism, farms, small shops, and businesses can be privately owned but are subject to government regulation. The other area on which socialists disagree is on what level society should exert its control. In communist countries like the former Soviet Union, China, Vietnam, and North Korea, the national government exerts control over the economy centrally. They had the power to tell all businesses what to produce, how much to produce, and what to charge for it. Other socialists believe control should be decentralized so it can be exerted by those most affected by the industries being controlled. An example of this would be a town collectively owning and managing the businesses on which its populace depends. Because of challenges in their economies, several of these communist countries have moved from central planning to letting market forces help determine many production and pricing decisions. Market socialism describes a subtype of socialism that adopts certain traits of capitalism, like allowing limited private ownership or consulting market demands. This could involve situations like profits generated by a company going directly to the employees of the company or being used as public funds (Gregory and Stuart 2003). Many Eastern European and some South American countries have mixed economies. Key industries are nationalized and directly controlled by the government; however, most businesses are privately owned and regulated by the government. Organized socialism never became powerful in the United States. The success of labor unions and the government in securing workers’ rights, joined with the high standard of living enjoyed by most of the workforce, made socialism less appealing than the controlled capitalism practiced here. Socialism in Practice As with capitalism, the basic ideas behind socialism go far back in history. Plato, in ancient Greece, suggested a republic in which people shared their material goods. Early Christian communities believed in common ownership, as did the systems of monasteries set up by various religious orders. Many of the leaders of the French Revolution called for the abolition of all private property, not just the estates of the aristocracy they had overthrown. Thomas More's Utopia , published in 1516, imagined a society with little private property and mandatory labor on a communal farm. Most experimental utopian communities had the abolition of private property as a founding principle. Modern socialism really began as a reaction to the excesses of uncontrolled industrial capitalism in the 1800s and 1900s. The enormous wealth and lavish lifestyles enjoyed by owners contrasted sharply with the miserable conditions of the workers. Some of the first great sociological thinkers studied the rise of socialism. Max Weber admired some aspects of socialism, especially its rationalism and how it could help social reform, but he worried that letting the government have complete control could result in an "iron cage of future bondage" (Greisman and Ritzer 1981). Pierre-Joseph Proudon (1809−1865) was another early socialist who thought socialism could be used to create utopian communities. In his 1840 book, What Is Property? , he famously stated that “property is theft” (Proudon 1840). By this he meant that if an owner did not work to produce or earn the property, then the owner was stealing it from those who did. Proudon believed economies could work using a principle called mutualism , under which individuals and cooperative groups would exchange products with one another on the basis of mutually satisfactory contracts (Proudon 1840). By far the most important influential thinker on socialism was Karl Marx. Through his own writings and those with his collaborator, industrialist Friedrich Engels, Marx used a scientific analytical process to show that throughout history the resolution of class struggles caused changes in economies. He saw the relationships evolving from slave and owner, to serf and lord, to journeyman and master, to worker and owner. Neither Marx nor Engels thought socialism could be used to set up small utopian communities. Rather, they believed a socialist society would be created after workers rebelled against capitalistic owners and seized the means of production. They felt industrial capitalism was a necessary step that raised the level of production in society to a point it could progress to a socialist state (Marx and Engels 1848). These ideas formed the basis of the sociological perspective of social conflict theory. Sociology in the Real World Obama and Socialism: A Few Definitions In the 2008 presidential election, the Republican Party latched onto what is often considered a dirty word to describe then-Senator Barack Obama’s politics: socialist. It may have been because the president was campaigning by telling workers it’s good for everybody when wealth gets spread around. But whatever the reason, the label became a weapon of choice for Republicans during and after the campaign. In 2012, Republican presidential contender Rick Perry continued this battle cry. A New York Times article quotes him as telling a group of Republicans in Texas that President Obama is “hell bent on taking America towards a socialist country” (Wheaton 2011). Meanwhile, during the first few years of his presidency, Obama worked to create universal health care coverage and pushed forth a partial takeover of the nation’s failing automotive industry. So does this make him a socialist? What does that really mean, anyway? There is more than one definition of socialism, but it generally refers to an economic or political theory that advocates for shared or governmental ownership and administration of production and distribution of goods. Often held up in counterpoint to capitalism, which encourages private ownership and production, socialism is not typically an all-or-nothing plan. For example, both the United Kingdom and France, as well as other European countries, have socialized medicine, meaning that medical services are run nationally to reach as many people as possible. These nations are, of course, still essentially capitalist countries with free-market economies. So is Obama a socialist because he wants universal health care? Or is the word a lightning rod for conservatives who associate it with a lack of personal freedom? By almost any measure, the answer is more the latter. A look at the politics of President Obama and Democrats in general shows that there is, compared to most other free-market countries, very little limitation on private ownership and production. What this is, instead, is an attempt to ensure that the United States, like all other core nations, has a safety net for its poorest and most vulnerable. Although it might be in Perry’s best interest to label this socialism, a study of the term makes it clear that it is untrue. Voters can go to the polls confident that, whoever their choice of candidate may be, socialism is far from finding a home in the United States. Convergence Theory We have seen how the economies of some capitalist countries such as the United States have features that are very similar to socialism. Some industries, particularly utilities, are either owned by the government or controlled through regulations. Public programs such as welfare, Medicare, and Social Security exist to provide public funds for private needs. We have also seen how several large communist (or formerly communist) countries such as Russia, China, and Vietnam have moved from state-controlled socialism with central planning to market socialism, which allows market forces to dictate prices and wages, and for some business to be privately owned. In many formerly communist countries, these changes have led to economic growth compared to the stagnation they experienced under communism (Fidrmuc 2002). In studying the economies of developing countries to see if they go through the same stages as previously developed nations did, sociologists have observed a pattern they call convergence. This describes the theory that societies move toward similarity over time as their economies develop. Convergence theory explains that as a country's economy grows, its societal organization changes to become more like that of an industrialized society. Rather than staying in one job for a lifetime, people begin to move from job to job as conditions improve and opportunities arise. This means the workforce needs continual training and retraining. Workers move from rural areas to cities as they become centers of economic activity, and the government takes a larger role in providing expanded public services (Kerr et al. 1960). Supporters of the theory point to Germany, France, and Japan—countries that rapidly rebuilt their economies after World War II. They point out how, in the 1960s and 1970s, East Asian countries like Singapore, South Korea, and Taiwan converged with countries with developed economies. They are now considered developed countries themselves. The theory is also known as the catch-up effect because the economies of poor countries that have capital invested in them will generally grow faster than countries that are already wealthy. This allows the income of poorer countries to "catch up" under the right conditions (“Catch-up Effect” 2011). To experience this rapid growth, the economies of developing countries must to be able to attract inexpensive capital to invest in new businesses and to improve traditionally low productivity. They need access to new, international markets for buying the goods. If these characteristics are not in place, then their economies cannot catch up. This is why the economies of some countries are diverging rather than converging (Abramovitz 1986). Another key characteristic of economic growth regards the implementation of technology. A developing country can bypass some steps of implementing technology that other nations faced earlier. Television and telephone systems are a good example. While developed countries spent significant time and money establishing elaborate system infrastructures based on metal wires or fiber-optic cables, developing countries today can go directly to cell phone and satellite transmission with much less investment. Another factor affects convergence concerning social structure. Early in their development, countries such as Brazil and Cuba had economies based on cash crops (coffee or sugarcane, for instance) grown on large plantations by unskilled workers. The elite ran the plantations and the government, with little interest in training and educating the populace for other endeavors. This retarded economic growth until the power of the wealthy plantation owners was challenged (Sokoloff and Engerman 2000). Improved economies generally lead to wider social improvement. Society benefits from improved educational systems, allowing people more time to devote to learning and leisure. Theoretical Perspectives on the Economy Now that we’ve developed an understanding of the history and basic components of economies, let’s turn to theory. How might social scientists study these topics? What questions do they ask? What theories do they develop to add to the body of sociological knowledge? Functionalist Perspective Someone taking a functional perspective will most likely view work and the economy as a well-oiled machine, designed for maximum efficiency. The Davis-Moore thesis, for example, suggests that some social stratification is a social necessity. The need for certain highly skilled positions combined with the relative difficulty of the occupation and the length of time it takes to qualify will result in a higher reward for that job, providing a financial motivation to engage in more education and a more difficult profession (Davis and Moore 1945). This theory can be used to explain the prestige and salaries that go to those with doctorates or medical degrees. Like any theory, this is subject to criticism. For example, the thesis fails to take into account the many people who spend years on their education only to pursue work at a lower-paying position in a nonprofit organization, or who teach high school after pursuing a PhD. It also fails to acknowledge the effect of life changes and social networks on individual opportunities. The functionalist perspective would assume that the continued health of the economy is vital to the health of the nation, as it ensures the distribution of goods and services. For example, we need food to travel from farms (high-functioning and efficient agricultural systems) via roads (safe and effective trucking and rail routes) to urban centers (high-density areas where workers can gather). However, sometimes a dysfunction––a function with the potential to disrupt social institutions or organization (Merton 1968)––in the economy occurs, usually because some institutions fail to adapt quickly enough to changing social conditions. This lesson has been driven home recently with the bursting of the housing bubble. Due to irresponsible lending practices and an underregulated financial market, we are currently living with the after-effects of a major dysfunction. Some of this is cyclical. Markets produce goods as they are supposed to, but eventually the market is saturated and the supply of goods exceeds the demands. Typically the market goes through phases of surplus, or excess, inflation, where the money in your pocket today buys less than it did yesterday, and recession , which occurs when there are two or more consecutive quarters of economic decline. The functionalist would say to let market forces fluctuate in a cycle through these stages. In reality, to control the risk of an economic depression (a sustained recession across several economic sectors), the U.S. government will often adjust interest rates to encourage more spending. In short, letting the natural cycle fluctuate is not a gamble most governments are willing to take. Conflict Perspective For a conflict perspective theorist, the economy is not a source of stability for society. Instead, the economy reflects and reproduces economic inequality, particularly in a capitalist marketplace. The conflict perspective is classically Marxist, with the bourgeoisie (ruling class) accumulating wealth and power by exploiting the proletariat (workers), and regulating those who cannot work (the aged, the infirm) into the great mass of unemployed (Marx and Engels 1848). From the symbolic (though probably made up) statement of Marie Antoinette, who purportedly said “Let them eat cake” when told that the peasants were starving, to the Occupy Wall Street movement, the sense of inequity is almost unchanged. Both the people fighting in the French Revolution and those blogging from Zuccotti Park believe the same thing: wealth is concentrated in the hands of those who do not deserve it. As of 2007, 20 percent of Americans owned 80 percent of U.S. wealth (Domhoff 2011). While the inequality might not be as extreme as in pre-revolutionary France, it is enough to make many believe that the United States is not the meritocracy it seems to be. Symbolic Interactionist Perspective Those working in the symbolic interaction perspective take a microanalytical view of society, focusing on the way reality is socially constructed through day-to-day interaction and how society is composed of people communicating based on a shared understanding of symbols. One important symbolic interactionist concept related to work and the economy is career inheritance . This concept means simply that children tend to enter the same or similar occupation as their parents, a correlation that has been demonstrated in research studies (Antony 1998). For example, the children of police officers learn the norms and values that will help them succeed in law enforcement, and since they have a model career path to follow, they may find law enforcement even more attractive. Related to career inheritance is career socialization, learning the norms and values of a particular job. Finally, a symbolic interactionist might study what contributes to job satisfaction. Melving Kohn and his fellow researchers (1990) determined that workers were most likely to be happy when they believed they controlled some part of their work, when they felt they were part of the decision-making processes associated with their work, when they have freedom from surveillance, and when they felt integral to the outcome of their work. Sunyal, Sunyal, and Yasin (2011) found that a greater sense of vulnerability to stress, the more stress experienced by a worker, and a greater amount of perceived risk consistently predicted a lower worker job satisfaction. 18.2 Globalization and the Economy What Is Globalization? Globalization refers to the process of integrating governments, cultures, and financial markets through international trade into a single “world market.” Often, the process begins with a single motive, such as market expansion (on the part of a corporation) or increased access to health care (on the part of a nonprofit organization). But usually there is a snowball effect, and globalization becomes a mixed bag of economic, philanthropic, entrepreneurial, and cultural efforts. Sometimes the efforts have obvious benefits, even for those who worry about cultural colonialism, such as campaigns to bring clean-water technology to rural areas without access to safe drinking water. Other globalization efforts, however, are more complex. Let us look, for example, at the free-trade agreement known as NAFTA (North American Free Trade Agreement). The agreement is among the countries of North America, including Canada, the United States, and Mexico, allowing much freer trade opportunities without the kind of tariffs (taxes) and import laws that restrict international trade. Often, trade opportunities are misrepresented by politicians and economists, who sometimes offer them up as a panacea to economic woes. For example, trade can lead to both increases and decreases in job opportunities. This is because while easier, more lax export laws mean there is the potential for job growth in the U.S., imports can mean the exact opposite. As Americans import more goods from outside the country, jobs typically decrease, as more and more products are made overseas. Many prominent economists believed that when NAFTA was created in 1994 it would lead to major gains in jobs. But by 2010, the evidence showed an opposite impact; the data showed 682,900 U.S. jobs lost across all states (Parks 2011). While NAFTA did increase the flow of goods and capital across the northern and southern U.S. borders, it also increased unemployment in Mexico, spurring greater amounts of illegal immigration motivated by a search for work. There are several forces driving globalization, including the global economy and multinational corporations that control assets, sales, production, and employment (United Nations 1973). Characteristics of multinational corporations include the following: A large share of their capital is collected from a variety of different nations, their business is conducted without regard to national borders, they concentrate wealth in the hands of core nations and already wealthy individuals, and they play a key role in the global economy. There are several components to the global economy and many changes that occur as countries grow more interdependent. First, there is an increasing number of global cities , which headquarter multinational corporations, such as Coca-Cola exercise significant international political influence, such as what comes from Beijing or Berlin host headquarters of international nongovernmental organizations (NGOs) such as the United Nations host influential media such as the BBC and Al Jazeera host advanced communication and transportation infrastructure, such as is seen in Shanghai (Sassen 2001) Second, we see the emergence of global assembly lines , where products are assembled over the course of several international transactions. For instance, Apple designs its next-generation Mac prototype in the United States, components are made in various peripheral nations, they are then shipped to another peripheral nation such as Malaysia for assembly, and tech support is outsourced to India. Globalization has also led to the development of global commodity chains , where internationally integrated economic links connect workers and corporations for the purpose of manufacture and marketing (Plahe 2005). For example, in maquiladoras , mostly found in northern Mexico, workers may sew imported precut pieces of fabric into garments. Globalization also brings an international division of labor, in which comparatively wealthy workers from core nations compete with the low-wage labor pool of peripheral and semi-peripheral nations. This can lead to a sense of xenophobia , which is an illogical fear and even hatred of foreigners and foreign goods. Corporations trying to maximize their profits in the United States are conscious of this risk and attempt to “Americanize” their products, selling shirts printed with U.S. flags that were nevertheless made in Mexico. Aspects of Globalization Globalized trade is nothing new. Societies in ancient Greece and Rome traded with other societies in Africa, the Middle East, India, and China. Trade expanded further during the Islamic Golden Age and after the rise of the Mongol Empire. The establishment of colonial empires after the voyages of discovery by European countries meant that trade was going on all over the world. In the 19th century, the Industrial Revolution led to even more trade of ever-increasing amounts of goods. However, the advance of technology, especially communications, after World War II and the Cold War triggered the explosive acceleration in the process occurring today. One way to look at the similarities and differences that exist among the economies of different nations is to compare their standards of living. The statistic most commonly used to do this is the domestic process per capita. This is the gross domestic product, or GDP, of a country divided by its population. The table below compares the top 11 countries with the bottom 11 out of the 228 countries listed in the CIA World Factbook . Rank Country GDP - per capita (PPP) 1 Qatar $179,000 2 Liechtenstein $141,100 3 Luxembourg $82,600 4 Bermuda $69,900 5 Singapore $62,100 6 Jersey $57,000 7 Norway $54,600 8 Brunei $51,600 9 United Arab Emirates $49,600 10 Kuwait $48,900 11 United States $47,200 218 Sierra Leone $900 219 Madagascar $900 220 Malawi $800 221 Niger $700 222 Central African Republic $700 223 Somalia $600 224 Eritrea $600 225 Zimbabwe $500 226 Liberia $500 227 Democratic Republic of Congo $300 228 Burundi $300 Table 18.1 Gross Domestic Product Per Capita Not every country is benefitting from globalization. The GDP per capita of the poorest countries is 600 times less than that of the wealthiest countries. (Table courtesy of the CIA, World Factbook 2004) There are benefits and drawbacks to globalization. Some of the benefits include the exponentially accelerated progress of development, the creation of international awareness and empowerment, and the potential for increased wealth (Abedian 2002). However, experience has shown that countries can also be weakened by globalization. Some critics of globalization worry about the growing influence of enormous international financial and industrial corporations that benefit the most from free trade and unrestricted markets. They fear these corporations can use their vast wealth and resources to control governments to act in their interest rather than that of the local population (Bakan 2004). Indeed, when looking at the countries at the bottom of the list above, we are looking at places where the primary benefactors of mineral exploitation are major corporations and a few key political figures. Nigeria, for example, is a country that produces tens of billions of dollars in oil revenue, but the money does not go to the country’s people. Other critics oppose globalization for what they see as negative impacts on the environment and local economies. Rapid industrialization, often a key component of globalization, can lead to widespread economic damage due to the lack of regulatory environment (Speth 2003). Further, as there are often no social institutions in place to protect workers in countries where jobs are scarce, some critics state that globalization leads to weak labor movements (Boswell and Stevis 1997). Finally, critics are concerned that wealthy countries can force economically weaker nations to open their markets while protecting their own local products from competition (Wallerstein 1974). This can be particularly true of agricultural products, which are often one of the main exports of poor and developing countries (Koroma 2007). In a 2007 article for the United Nations, Koroma discusses the difficulties faced by “least developed countries” (LDCs) that seek to participate in globalization efforts. These countries typically lack the infrastructure to be flexible and nimble in their production and trade, and therefore are vulnerable to everything from unfavorable weather conditions to international price volatility. In short, rather than offering them more opportunities, the increased competition and fast pace of a globalized market can make it more challenging than ever for LDCs to move forward (Koroma 2007). The increasing use of outsourcing of manufacturing and service-industry jobs to developing countries has caused increased unemployment in some developed countries. Countries that do not develop new jobs to replace those that move, and train their labor force to do them, will find support for globalization weakening. 18.3 Work in the United States The American Dream has always been based on opportunity. There is a great deal of mythologizing about the energetic upstart who can climb to success based on hard work alone. Common wisdom states that if you study hard, develop good work habits, and graduate high school or, even better, college, then you'll have the opportunity to land a good job. That has long been seen as the key to a successful life. And although the reality has always been more complex than suggested by the myth, the worldwide recession that began in 2008 has made it harder than ever to play by the rules and win the game. The data are grim: From December 2007 through March 2010, 8.2 million workers in the United States lost their jobs, and the unemployment rate grew to almost 10 percent nationally, with some states showing much higher rates (Autor 2010). Times are very challenging for those in the workforce. For those looking to finish their schooling, often with enormous student-debt burdens, it is not just challenging—it is terrifying. So where did all the jobs go? Will any of them be coming back, and if not, what new ones will there be? How do you find and keep a good job now? These are the kinds of questions people are currently asking about the job market in the United States. Real Money, Virtual Worlds If you are not one of the tens of millions gamers who enjoy World of Warcraft or other online virtual world games, you might not even know what MMORPG stands for. But if you made a living playing MMORPGs, as a growing number of enterprising gamers do, then massive multiplayer online role-playing games might matter a bit more. According to an article in Forbes magazine, the online world of gaming has been yielding very real profits for entrepreneurs who are able to buy, sell, and manage online real estate, currency, and more for cash (Holland and Ewalt 2006). If it seems strange that people would pay real money for imaginary goods, consider that for serious gamers the online world is of equal importance to the real one. These entrepreneurs can sell items because the gaming sites have introduced scarcity into the virtual worlds. The game makers have realized that MMORPGs lack tension without a level of scarcity for needed resources or highly desired items. In other words, if anyone can have a palace or a vault full of wealth, then what’s the fun? So how does it work? One of the easiest ways to make such a living is called gold farming, which involves hours of repetitive and boring play, hunting and shooting animals like dragons that carry a lot of wealth. This virtual wealth can be sold on eBay for real money: a timesaver for players who don’t want to waste their playing time on boring pursuits. Players in parts of Asia engage in gold farming, playing eight hours a day or more, to sell their gold to players in Western Europe or North America. From virtual prostitutes to power levelers (people who play the game logged in as you so your characters get the wealth and power), to architects, merchants, and even beggars, online players can offer to sell any service or product that others want to buy. Whether buying a magic carpet in World of Warcraft or a stainless-steel kitchen appliance in Second Life, gamers have the same desire to acquire as the rest of us—never mind that their items are virtual. Once a gamer creates the code for an item, she can sell it again and again, for real money. And finally, you can sell yourself. According to Forbes , a University of Virginia computer science student sold his World of Warcraft character on eBay for $1,200, due to the high levels of powers and skills it had gained (Holland and Ewalt 2006). So should you quit your day job to make a killing in online games? Probably not. Those who work hard might eke out a decent living, but for most people, grabbing up land that doesn’t really exist or selling your body in animated action scenes is probably not the best opportunity. Still, for some, it offers the ultimate in work-from-home flexibility, even if that home is a mountain cave in a virtual world. Polarization in the Workforce The mix of jobs available in the United States began changing many years before the recession struck, and, as mentioned above, the American dream has not always been easy to follow. Geography, race, gender, and other factors have always played a role in the reality of success. More recently, the increased outsourcing (or contracting a job or set of jobs to an outside source) of manufacturing jobs to developing nations has greatly diminished the number of high-paying, often unionized, blue-collar positions available. A similar problem has arisen in the white-collar sector, with many low-level clerical and support positions also being outsourced, as evidenced by the international technical-support call centers in Mumbai, India, and Newfoundland, Canada. The number of supervisory and managerial positions has been reduced as companies streamline their command structures and industries continue to consolidate through mergers. Even highly educated skilled workers such as computer programmers have seen their jobs vanish overseas. The automation (replacing workers with technology) of the workplace is another cause of the changes in the job market. Computers can be programmed to do many routine tasks faster and less expensively than people who used to do such tasks. Jobs like bookkeeping, clerical work, and repetitive tasks on production assembly lines all lend themselves to automation. Think about the newer automated toll passes we can install in our cars. Toll collectors are just one of the many endangered jobs that will soon cease to exist. Despite all this, the job market is actually growing in some areas, but in a very polarized fashion. Polarization means that a gap has developed in the job market, with most employment opportunities at the lowest and highest levels and few jobs for those with midlevel skills and education. At one end, there has been strong demand for low-skilled, low-paying jobs in industries like food service and retail. On the other end, some research shows that in certain fields there has been a steadily increasing demand for highly skilled and educated professionals, technologists, and managers. These high-skilled positions also tend to be highly paid (Autor 2010). The fact that some positions are highly paid while others are not is an example of the class system, an economic hierarchy in which movement (both upward and downward) between various rungs of the socioeconomic ladder is possible. Theoretically, at least, the class system as it is organized in the United States is an example of a meritocracy, an economic system that rewards merit––typically in the form of skill and hard work––with upward mobility. A theorist working in the functionalist perspective might point out that this system is designed to reward hard work, which encourages people to strive for excellence in pursuit of reward. A theorist working in the conflict perspective might counter with the thought that hard work does not guarantee success even in a meritocracy, because social capital––the accumulation of a network of social relationships and knowledge that will provide a platform from which to achieve financial success––in the form of connections or higher education are often required to access the high-paying jobs. Increasingly, we are realizing intelligence and hard work aren’t enough. If you lack knowledge of how to leverage the right names, connections, and players, you are unlikely to experience upward mobility. With so many jobs being outsourced or eliminated by automation, what kind of jobs are there a demand for in the United States? While fishing and forestry jobs are in decline, in several markets jobs are increasing. These include community and social service, personal care and service, finance, computer and information services, and health care. The chart below, from the U.S. Bureau of Labor Statistics, illustrates areas of projected growth. The professional and related jobs, which include any number of positions, typically require significant education and training and tend to be lucrative career choices. Service jobs, according to the Bureau of Labor Statistics, can include everything from jobs with the fire department to jobs scooping ice cream (Bureau of Labor Statistics 2010). There is a wide variety of training needed, and therefore an equally large wage potential discrepancy. One of the largest areas of growth by industry, rather than by occupational group (as seen above), is in the health field. This growth is across occupations, from associate-level nurse’s aides to management-level assisted-living staff. As baby boomers age, they are living longer than any generation before, and the growth of this population segment requires an increase in capacity throughout our country’s elder care system, from home health care nursing to geriatric nutrition. Notably, jobs in farming are in decline. This is an area where those with less education traditionally could be assured of finding steady, if low-wage, work. With these jobs disappearing, more and more workers will find themselves untrained for the types of employment that are available. Another projected trend in employment relates to the level of education and training required to gain and keep a job. As the chart below shows us, growth rates are higher for those with more education. Those with a professional degree or a master’s degree may expect job growth of 20 and 22 percent respectively, and jobs that require a bachelor’s degree are projected to grow 17 percent. At the other end of the spectrum, jobs that require a high school diploma or equivalent are projected to grow at only 12 percent, while jobs that require less than a high school diploma will grow 14 percent. Quite simply, without a degree, it will be more difficult to find a job. It is worth noting that these projections are based on overall growth across all occupation categories, so obviously there will be variations within different occupational areas. However, once again, those who are the least educated will be the ones least able to fulfill the American Dream. In the past, rising education levels in the United States had been able to keep pace with the rise in the number of education-dependent jobs. However, since the late 1970s, men have been enrolling in college at a lower rate than women, and graduating at a rate of almost 10 percent less. The lack of male candidates reaching the education levels needed for skilled positions has opened opportunities for women, minorities, and immigrants (Wang 2011). Women in the Workforce Women have been entering the workforce in ever-increasing numbers for several decades. They have also been finishing college and going on to earn higher degrees at higher rate than men do. This has resulted in many women being better positioned to obtain high-paying, high-skill jobs (Autor 2010). While women are getting more and better jobs and their wages are rising more quickly than men's wages are, U.S. Census statistics show that they are still earning only 77 percent of what men are for the same positions (U.S. Census Bureau 2010). Immigration and the Workforce Simply put, people will move from where there are few or no jobs to places where there are jobs, unless something prevents them from doing so. The process of moving to a country is called immigration. Due to its reputation as the land of opportunity, the United States has long been the destination of all skill levels of workers. While the rate decreased somewhat during the economic slowdown of 2008, immigrants, both legal and illegal, continue to be a major part of the U.S. workforce. In 2005, before the recession arrived, immigrants made up a historic high of 14.7 percent of the workforce (Lowell et al. 2006). During the 1970s through 2000s, the United States experienced both an increase in college-educated immigrants and in immigrants who lacked a high school diploma. With this range across the spectrum, immigrants are well positioned for both the higher-paid jobs and the low-wage low-skill jobs that are predicted to grow in the next decade (Lowell et al. 2006). In the early 2000s, it certainly seemed that the United States was continuing to live up to its reputation of opportunity. But what about during the recession of 2008, when so many jobs were lost and unemployment hovered close to 10 percent? How did immigrant workers fare then? The answer is that as of June 2009, when the National Bureau of Economic Research (NEBR) declared the recession officially over, “foreign-born workers gained 656,000 jobs while native-born workers lost 1.2 million jobs” (Kochhar 2010). As these numbers suggest, the unemployment rate that year decreased for immigrant workers and increased for native workers. The reasons for this trend are not entirely clear. Some Pew research suggests immigrants tend to have greater flexibility to move from job to job and that the immigrant population may have been early victims of the recession, and thus were quicker to rebound (Kochhar 2010). Regardless of the reasons, the 2009 job gains are far from enough to keep them inured from the country’s economic woes. Immigrant earnings are in decline, even as the number of jobs increases, and some theorize that increase in employment may come from a willingness to accept significantly lower wages and benefits. While the political debate is often fueled by conversations about low-wage-earning immigrants, there are actually as many highly skilled––and high-earning––immigrant workers as well. Many immigrants are sponsored by their employers who claim they possess talents, education, and training that are in short supply in the U.S. These sponsored immigrants account for 15 percent of all legal immigrants (Batalova and Terrazas 2010). Interestingly, the U.S. population generally supports these high-level workers, believing they will help lead to economic growth and not be a drain on government services (Hainmueller and Hiscox 2010). On the other hand, illegal immigrants tend to be trapped in extremely low-paying jobs in agriculture, service, and construction with few ways to improve their situation without risking exposure and deportation. Poverty in the United States When people lose their jobs during a recession or in a changing job market, it takes longer to find a new one, if they can find one at all. If they do, it is often at a much lower wage or not full time. This can force people into poverty. In the United States, we tend to have what is called relative poverty, defined as being unable to live the lifestyle of the average person in your country. This must be contrasted with the absolute poverty that can be found in underdeveloped countries, defined as being barely able, or unable, to afford basic necessities such as food (Byrns 2011). We cannot even rely on unemployment statistics to provide a clear picture of total unemployment in the United States. First, unemployment statistics do not take into account underemployment , a state in which a person accepts a lower paying, lower status job than their education and experience qualifies them to perform. Second, unemployment statistics only count those: who are actively looking for work who have not earned income from a job in the past four weeks who are ready, willing, and able to work The unemployment statistics provided by the U.S. government are rarely accurate, because many of the unemployed become discouraged and stop looking for work. Not only that, but these statistics undercount the youngest and oldest workers, the chronically unemployed (e.g., homeless), and seasonal and migrant workers. A certain amount of unemployment is a direct result of the relative inflexibility of the labor market, considered structural unemployment , which describes when there is a societal level of disjuncture between people seeking jobs and the available jobs. This mismatch can be geographic (they are hiring in California, but most unemployed live in Alabama), technological (skilled workers are replaced by machines, as in the auto industry), or can result from any sudden change in the types of jobs people are seeking versus the types of companies that are hiring. Because of the high standard of living in the United States, many people are working at full-time jobs but are still poor by the standards of relative poverty. They are the working poor. The United States has a higher percentage of working poor than many other developed countries (Brady, Fullerton and Cross 2010). In terms of employment, the Bureau of Labor Statistics defines the working poor as those who have spent at least 27 weeks working or looking for work, and yet remain below the poverty line. Many of the facts about the working poor are as expected: Those who work only part time are more likely to be classified as working poor than those with full-time employment; higher levels of education lead to less likelihood of being among the working poor; and those with children under 18 are four times more likely than those without children to fall into this category. In 2009, the working poor included 10.4 million Americans, up almost 17 percent from 2008 (U.S. Bureau of Labor Statistics 2011). Most developed countries such as the United States protect their citizens from absolute poverty by providing different levels of social services such as unemployment insurance, welfare, food stamps, and so on. They may also provide job training and retraining so that people can reenter the job market. In the past, the elderly were particularly vulnerable to falling into poverty after they stopped working; however, pensions, retirement plans, and Social Security were designed to help prevent this. A major concern in the United States is the rising number of young people growing up in poverty. Growing up poor can cut off access to the education and services people need to move out of poverty and into stable employment. As we saw, more education was often a key to stability, and those raised in poverty are the ones least able to find well-paying work, perpetuating a cycle. There is great debate about how much support local, state, and federal governments should give to help the unemployed and underemployed. The decisions made on these issues will have a profound effect on working in the United States.
biology
Chapter Outline 32.1 Reproductive Development and Structure 32.2 Pollination and Fertilization 32.3 Asexual Reproduction Introduction Plants have evolved different reproductive strategies for the continuation of their species. Some plants reproduce sexually, and others asexually, in contrast to animal species, which rely almost exclusively on sexual reproduction. Plant sexual reproduction usually depends on pollinating agents, while asexual reproduction is independent of these agents. Flowers are often the showiest or most strongly scented part of plants. With their bright colors, fragrances, and interesting shapes and sizes, flowers attract insects, birds, and animals to serve their pollination needs. Other plants pollinate via wind or water; still others self-pollinate.
[ { "answer": { "ans_choice": 1, "ans_text": "microsporangium" }, "bloom": null, "hl_context": "The male gametophyte develops and reaches maturity in an immature anther . <hl> In a plant ’ s male reproductive organs , development of pollen takes place in a structure known as the microsporangium ( Figure 32.6 ) . <hl> The microsporangia , which are usually bi-lobed , are pollen sacs in which the microspores develop into pollen grains . These are found in the anther , which is at the end of the stamen — the long filament that supports the anther . Within the microsporangium , the microspore mother cell divides by meiosis to give rise to four microspores , each of which will ultimately form a pollen grain ( Figure 32.7 ) . An inner layer of cells , known as the tapetum , provides nutrition to the developing microspores and contributes key components to the pollen wall . Mature pollen grains contain two cells : a generative cell and a pollen tube cell . The generative cell is contained within the larger pollen tube cell . Upon germination , the tube cell forms the pollen tube through which the generative cell migrates to enter the ovary . During its transit inside the pollen tube , the generative cell divides to form two male gametes ( sperm cells ) . Upon maturity , the microsporangia burst , releasing the pollen grains from the anther .", "hl_sentences": "In a plant ’ s male reproductive organs , development of pollen takes place in a structure known as the microsporangium ( Figure 32.6 ) .", "question": { "cloze_format": "In a plant’s male reproductive organs, development of pollen takes place in a structure known as the ________.", "normal_format": "In a plant’s male reproductive organs, what is development of pollen that takes place in a structure known as?", "question_choices": [ "stamen", "microsporangium", "anther", "tapetum" ], "question_id": "fs-idm85330784", "question_text": "In a plant’s male reproductive organs, development of pollen takes place in a structure known as the ________." }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 3, "ans_text": "anther" }, "bloom": null, "hl_context": "The male gametophyte develops and reaches maturity in an immature anther . In a plant ’ s male reproductive organs , development of pollen takes place in a structure known as the microsporangium ( Figure 32.6 ) . The microsporangia , which are usually bi-lobed , are pollen sacs in which the microspores develop into pollen grains . <hl> These are found in the anther , which is at the end of the stamen — the long filament that supports the anther . <hl> Within the microsporangium , the microspore mother cell divides by meiosis to give rise to four microspores , each of which will ultimately form a pollen grain ( Figure 32.7 ) . An inner layer of cells , known as the tapetum , provides nutrition to the developing microspores and contributes key components to the pollen wall . Mature pollen grains contain two cells : a generative cell and a pollen tube cell . The generative cell is contained within the larger pollen tube cell . Upon germination , the tube cell forms the pollen tube through which the generative cell migrates to enter the ovary . During its transit inside the pollen tube , the generative cell divides to form two male gametes ( sperm cells ) . Upon maturity , the microsporangia burst , releasing the pollen grains from the anther .", "hl_sentences": "These are found in the anther , which is at the end of the stamen — the long filament that supports the anther .", "question": { "cloze_format": "The stamen consists of a long stalk called the filament that supports the ________.", "normal_format": "What does filament the stamen consists of a long stalk, support?", "question_choices": [ "stigma", "sepal", "style", "anther" ], "question_id": "fs-idm51172912", "question_text": "The stamen consists of a long stalk called the filament that supports the ________." }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 0, "ans_text": "sepals" }, "bloom": null, "hl_context": "A typical flower has four main parts — or whorls — known as the calyx , corolla , androecium , and gynoecium ( Figure 32.3 ) . The outermost whorl of the flower has green , leafy structures known as sepals . <hl> The sepals , collectively called the calyx , help to protect the unopened bud . <hl> The second whorl is comprised of petals — usually , brightly colored — collectively called the corolla . The number of sepals and petals varies depending on whether the plant is a monocot or dicot . In monocots , petals usually number three or multiples of three ; in dicots , the number of petals is four or five , or multiples of four and five . Together , the calyx and corolla are known as the perianth . The third whorl contains the male reproductive structures and is known as the androecium . The androecium has stamens with anthers that contain the microsporangia . The innermost group of structures in the flower is the gynoecium , or the female reproductive component ( s ) . The carpel is the individual unit of the gynoecium and has a stigma , style , and ovary . A flower may have one or multiple carpels . Visual Connection", "hl_sentences": "The sepals , collectively called the calyx , help to protect the unopened bud .", "question": { "cloze_format": "The ________ are collectively called the calyx.", "normal_format": "Which are collectively called the calyx?", "question_choices": [ "sepals", "petals", "tepals", "stamens" ], "question_id": "fs-idm164560928", "question_text": "The ________ are collectively called the calyx." }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 0, "ans_text": "stigma" }, "bloom": null, "hl_context": "Pollination takes two forms : self-pollination and cross-pollination . <hl> Self-pollination occurs when the pollen from the anther is deposited on the stigma of the same flower , or another flower on the same plant . <hl> Cross-pollination is the transfer of pollen from the anther of one flower to the stigma of another flower on a different individual of the same species . Self-pollination occurs in flowers where the stamen and carpel mature at the same time , and are positioned so that the pollen can land on the flower ’ s stigma . This method of pollination does not require an investment from the plant to provide nectar and pollen as food for pollinators .", "hl_sentences": "Self-pollination occurs when the pollen from the anther is deposited on the stigma of the same flower , or another flower on the same plant .", "question": { "cloze_format": "The part of the flower the pollen lands on is the ___.", "normal_format": "The pollen lands on which part of the flower?", "question_choices": [ "stigma", "style", "ovule", "integument" ], "question_id": "fs-idm42465184", "question_text": "The pollen lands on which part of the flower?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 1, "ans_text": "endosperm" }, "bloom": null, "hl_context": "After pollen is deposited on the stigma , it must germinate and grow through the style to reach the ovule . The microspores , or the pollen , contain two cells : the pollen tube cell and the generative cell . The pollen tube cell grows into a pollen tube through which the generative cell travels . The germination of the pollen tube requires water , oxygen , and certain chemical signals . As it travels through the style to reach the embryo sac , the pollen tube ’ s growth is supported by the tissues of the style . In the meantime , if the generative cell has not already split into two cells , it now divides to form two sperm cells . The pollen tube is guided by the chemicals secreted by the synergids present in the embryo sac , and it enters the ovule sac through the micropyle . <hl> Of the two sperm cells , one sperm fertilizes the egg cell , forming a diploid zygote ; the other sperm fuses with the two polar nuclei , forming a triploid cell that develops into the endosperm . <hl> <hl> Together , these two fertilization events in angiosperms are known as double fertilization ( Figure 32.18 ) . <hl> After fertilization is complete , no other sperm can enter . The fertilized ovule forms the seed , whereas the tissues of the ovary become the fruit , usually enveloping the seed .", "hl_sentences": "Of the two sperm cells , one sperm fertilizes the egg cell , forming a diploid zygote ; the other sperm fuses with the two polar nuclei , forming a triploid cell that develops into the endosperm . Together , these two fertilization events in angiosperms are known as double fertilization ( Figure 32.18 ) .", "question": { "cloze_format": "After double fertilization, a zygote and ________ form.", "normal_format": "After double fertilization, a zygote and which of the following form?", "question_choices": [ "an ovule", "endosperm", "a cotyledon", "a suspensor" ], "question_id": "fs-idm61999936", "question_text": "After double fertilization, a zygote and ________ form." }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 1, "ans_text": "seed" }, "bloom": null, "hl_context": "Some plants can produce seeds without fertilization . <hl> Either the ovule or part of the ovary , which is diploid in nature , gives rise to a new seed . <hl> This method of reproduction is known as apomixis . After pollen is deposited on the stigma , it must germinate and grow through the style to reach the ovule . The microspores , or the pollen , contain two cells : the pollen tube cell and the generative cell . The pollen tube cell grows into a pollen tube through which the generative cell travels . The germination of the pollen tube requires water , oxygen , and certain chemical signals . As it travels through the style to reach the embryo sac , the pollen tube ’ s growth is supported by the tissues of the style . In the meantime , if the generative cell has not already split into two cells , it now divides to form two sperm cells . The pollen tube is guided by the chemicals secreted by the synergids present in the embryo sac , and it enters the ovule sac through the micropyle . Of the two sperm cells , one sperm fertilizes the egg cell , forming a diploid zygote ; the other sperm fuses with the two polar nuclei , forming a triploid cell that develops into the endosperm . Together , these two fertilization events in angiosperms are known as double fertilization ( Figure 32.18 ) . After fertilization is complete , no other sperm can enter . <hl> The fertilized ovule forms the seed , whereas the tissues of the ovary become the fruit , usually enveloping the seed . <hl>", "hl_sentences": "Either the ovule or part of the ovary , which is diploid in nature , gives rise to a new seed . The fertilized ovule forms the seed , whereas the tissues of the ovary become the fruit , usually enveloping the seed .", "question": { "cloze_format": "The fertilized ovule gives rise to the ________.", "normal_format": "The fertilized ovule gives rise to which of the following?", "question_choices": [ "fruit", "seed", "endosperm", "embryo" ], "question_id": "fs-idm18150016", "question_text": "The fertilized ovule gives rise to the ________." }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 3, "ans_text": "accessory fruit" }, "bloom": "1", "hl_context": "Fruits may be classified as simple , aggregate , multiple , or accessory , depending on their origin ( Figure 32.22 ) . If the fruit develops from a single carpel or fused carpels of a single ovary , it is known as a simple fruit , as seen in nuts and beans . An aggregate fruit is one that develops from more than one carpel , but all are in the same flower : the mature carpels fuse together to form the entire fruit , as seen in the raspberry . Multiple fruit develops from an inflorescence or a cluster of flowers . An example is the pineapple , where the flowers fuse together to form the fruit . <hl> Accessory fruits ( sometimes called false fruits ) are not derived from the ovary , but from another part of the flower , such as the receptacle ( strawberry ) or the hypanthium ( apples and pears ) . <hl> After fertilization , the ovary of the flower usually develops into the fruit . Fruits are usually associated with having a sweet taste ; however , not all fruits are sweet . Botanically , the term “ fruit ” is used for a ripened ovary . In most cases , flowers in which fertilization has taken place will develop into fruits , and flowers in which fertilization has not taken place will not . <hl> Some fruits develop from the ovary and are known as true fruits , whereas others develop from other parts of the female gametophyte and are known as accessory fruits . <hl> The fruit encloses the seeds and the developing embryo , thereby providing it with protection . Fruits are of many types , depending on their origin and texture . The sweet tissue of the blackberry , the red flesh of the tomato , the shell of the peanut , and the hull of corn ( the tough , thin part that gets stuck in your teeth when you eat popcorn ) are all fruits . As the fruit matures , the seeds also mature .", "hl_sentences": "Accessory fruits ( sometimes called false fruits ) are not derived from the ovary , but from another part of the flower , such as the receptacle ( strawberry ) or the hypanthium ( apples and pears ) . Some fruits develop from the ovary and are known as true fruits , whereas others develop from other parts of the female gametophyte and are known as accessory fruits .", "question": { "cloze_format": "The term for a fruit that develops from tissues other than the ovary is ___.", "normal_format": "What is the term for a fruit that develops from tissues other than the ovary?", "question_choices": [ "simple fruit", "aggregate fruit", "multiple fruit", "accessory fruit" ], "question_id": "fs-idm3491952", "question_text": "What is the term for a fruit that develops from tissues other than the ovary?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 2, "ans_text": "exocarp" }, "bloom": null, "hl_context": "<hl> Fruits generally have three parts : the exocarp ( the outermost skin or covering ) , the mesocarp ( middle part of the fruit ) , and the endocarp ( the inner part of the fruit ) . <hl> Together , all three are known as the pericarp . The mesocarp is usually the fleshy , edible part of the fruit ; however , in some fruits , such as the almond , the endocarp is the edible part . In many fruits , two or all three of the layers are fused , and are indistinguishable at maturity . Fruits can be dry or fleshy . Furthermore , fruits can be divided into dehiscent or indehiscent types . Dehiscent fruits , such as peas , readily release their seeds , while indehiscent fruits , like peaches , rely on decay to release their seeds .", "hl_sentences": "Fruits generally have three parts : the exocarp ( the outermost skin or covering ) , the mesocarp ( middle part of the fruit ) , and the endocarp ( the inner part of the fruit ) .", "question": { "cloze_format": "The ________ is the outermost covering of a fruit.", "normal_format": "What is the outermost covering of a fruit?", "question_choices": [ "endocarp", "pericarp", "exocarp", "mesocarp" ], "question_id": "fs-idp105300832", "question_text": "The ________ is the outermost covering of a fruit." }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 0, "ans_text": "grafting" }, "bloom": null, "hl_context": "<hl> Grafting has long been used to produce novel varieties of roses , citrus species , and other plants . <hl> <hl> In grafting , two plant species are used ; part of the stem of the desirable plant is grafted onto a rooted plant called the stock . <hl> The part that is grafted or attached is called the scion . Both are cut at an oblique angle ( any angle other than a right angle ) , placed in close contact with each other , and are then held together Figure 32.26 . Matching up these two surfaces as closely as possible is extremely important because these will be holding the plant together . The vascular systems of the two plants grow and fuse , forming a graft . After a period of time , the scion starts producing shoots , and eventually starts bearing flowers and fruits . Grafting is widely used in viticulture ( grape growing ) and the citrus industry . Scions capable of producing a particular fruit variety are grated onto root stock with specific resistance to disease . Many plants are able to propagate themselves using asexual reproduction . This method does not require the investment required to produce a flower , attract pollinators , or find a means of seed dispersal . Asexual reproduction produces plants that are genetically identical to the parent plant because no mixing of male and female gametes takes place . Traditionally , these plants survive well under stable environmental conditions when compared with plants produced from sexual reproduction because they carry genes identical to those of their parents . <hl> Many different types of roots exhibit asexual reproduction Figure 32.24 . <hl> <hl> The corm is used by gladiolus and garlic . <hl> <hl> Bulbs , such as a scaly bulb in lilies and a tunicate bulb in daffodils , are other common examples . <hl> <hl> A potato is a stem tuber , while parsnip propagates from a taproot . <hl> <hl> Ginger and iris produce rhizomes , while ivy uses an adventitious root ( a root arising from a plant part other than the main or primary root ) , and the strawberry plant has a stolon , which is also called a runner . <hl>", "hl_sentences": "Grafting has long been used to produce novel varieties of roses , citrus species , and other plants . In grafting , two plant species are used ; part of the stem of the desirable plant is grafted onto a rooted plant called the stock . Many different types of roots exhibit asexual reproduction Figure 32.24 . The corm is used by gladiolus and garlic . Bulbs , such as a scaly bulb in lilies and a tunicate bulb in daffodils , are other common examples . A potato is a stem tuber , while parsnip propagates from a taproot . Ginger and iris produce rhizomes , while ivy uses an adventitious root ( a root arising from a plant part other than the main or primary root ) , and the strawberry plant has a stolon , which is also called a runner .", "question": { "cloze_format": "________ is a useful method of asexual reproduction for propagating hard-to-root plants.", "normal_format": "What is a useful method of asexual reproduction for propagating hard-to-root plants?", "question_choices": [ "grafting", "layering", "cuttings", "budding" ], "question_id": "fs-idm62585872", "question_text": "________ is a useful method of asexual reproduction for propagating hard-to-root plants." }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 2, "ans_text": "When cuttings or buds are taken from an adult plant or plant parts, the resulting plant will grow into an adult faster than a seedling." }, "bloom": "3", "hl_context": "<hl> An advantage of asexual reproduction is that the resulting plant will reach maturity faster . <hl> Since the new plant is arising from an adult plant or plant parts , it will also be sturdier than a seedling . Asexual reproduction can take place by natural or artificial ( assisted by humans ) means .", "hl_sentences": "An advantage of asexual reproduction is that the resulting plant will reach maturity faster .", "question": { "cloze_format": "It is an advantage of asexual reproduction that ___.", "normal_format": "Which of the following is an advantage of asexual reproduction?", "question_choices": [ "Cuttings taken from an adult plant show increased resistance to diseases.", "Grafted plants can more successfully endure drought.", "When cuttings or buds are taken from an adult plant or plant parts, the resulting plant will grow into an adult faster than a seedling.", "Asexual reproduction takes advantage of a more diverse gene pool." ], "question_id": "fs-idm140387168", "question_text": "Which of the following is an advantage of asexual reproduction?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 3, "ans_text": "monocarpic" }, "bloom": null, "hl_context": "<hl> In another classification based on flowering frequency , monocarpic plants flower only once in their lifetime ; examples include bamboo and yucca . <hl> During the vegetative period of their life cycle ( which may be as long as 120 years in some bamboo species ) , these plants may reproduce asexually and accumulate a great deal of food material that will be required during their once-in-a-lifetime flowering and setting of seed after fertilization . Soon after flowering , these plants die . Polycarpic plants form flowers many times during their lifetime . Fruit trees , such as apple and orange trees , are polycarpic ; they flower every year . Other polycarpic species , such as perennials , flower several times during their life span , but not each year . By this means , the plant does not require all its nutrients to be channelled towards flowering each year .", "hl_sentences": "In another classification based on flowering frequency , monocarpic plants flower only once in their lifetime ; examples include bamboo and yucca .", "question": { "cloze_format": "Plants that flower once in their lifetime are known as ________.", "normal_format": "What are plants that flower once in their lifetime?", "question_choices": [ "monoecious", "dioecious", "polycarpic", "monocarpic" ], "question_id": "fs-idm161465152", "question_text": "Plants that flower once in their lifetime are known as ________." }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 2, "ans_text": "annuals" }, "bloom": null, "hl_context": "<hl> Plant species that complete their lifecycle in one season are known as annuals , an example of which is Arabidopsis , or mouse-ear cress . <hl> Biennials such as carrots complete their lifecycle in two seasons . In a biennial ’ s first season , the plant has a vegetative phase , whereas in the next season , it completes its reproductive phase . Commercial growers harvest the carrot roots after the first year of growth , and do not allow the plants to flower . Perennials , such as the magnolia , complete their lifecycle in two years or more .", "hl_sentences": "Plant species that complete their lifecycle in one season are known as annuals , an example of which is Arabidopsis , or mouse-ear cress .", "question": { "cloze_format": "Plant species that complete their lifecycle in one season are known as ________.", "normal_format": "Plant species that complete their lifecycle in one season are known as what?", "question_choices": [ "biennials", "perennials", "annuals", "polycarpic" ], "question_id": "fs-idm142328976", "question_text": "Plant species that complete their lifecycle in one season are known as ________." }, "references_are_paraphrase": null } ]
32
32.1 Reproductive Development and Structure Learning Objectives By the end of this section, you will be able to: Describe the two stages of a plant’s lifecycle Compare and contrast male and female gametophytes and explain how they form in angiosperms Describe the reproductive structures of a plant Describe the components of a complete flower Describe the development of microsporangium and megasporangium in gymnosperms Sexual reproduction takes place with slight variations in different groups of plants. Plants have two distinct stages in their lifecycle: the gametophyte stage and the sporophyte stage. The haploid gametophyte produces the male and female gametes by mitosis in distinct multicellular structures. Fusion of the male and females gametes forms the diploid zygote, which develops into the sporophyte . After reaching maturity, the diploid sporophyte produces spores by meiosis, which in turn divide by mitosis to produce the haploid gametophyte. The new gametophyte produces gametes, and the cycle continues. This is the alternation of generations, and is typical of plant reproduction ( Figure 32.2 ). The life cycle of higher plants is dominated by the sporophyte stage, with the gametophyte borne on the sporophyte. In ferns, the gametophyte is free-living and very distinct in structure from the diploid sporophyte. In bryophytes, such as mosses, the haploid gametophyte is more developed than the sporophyte. During the vegetative phase of growth, plants increase in size and produce a shoot system and a root system. As they enter the reproductive phase, some of the branches start to bear flowers. Many flowers are borne singly, whereas some are borne in clusters. The flower is borne on a stalk known as a receptacle. Flower shape, color, and size are unique to each species, and are often used by taxonomists to classify plants. Sexual Reproduction in Angiosperms The lifecycle of angiosperms follows the alternation of generations explained previously. The haploid gametophyte alternates with the diploid sporophyte during the sexual reproduction process of angiosperms. Flowers contain the plant’s reproductive structures. Flower Structure A typical flower has four main parts—or whorls—known as the calyx, corolla, androecium, and gynoecium ( Figure 32.3 ). The outermost whorl of the flower has green, leafy structures known as sepals. The sepals, collectively called the calyx, help to protect the unopened bud. The second whorl is comprised of petals—usually, brightly colored—collectively called the corolla. The number of sepals and petals varies depending on whether the plant is a monocot or dicot. In monocots, petals usually number three or multiples of three; in dicots, the number of petals is four or five, or multiples of four and five. Together, the calyx and corolla are known as the perianth . The third whorl contains the male reproductive structures and is known as the androecium. The androecium has stamens with anthers that contain the microsporangia. The innermost group of structures in the flower is the gynoecium , or the female reproductive component(s). The carpel is the individual unit of the gynoecium and has a stigma, style, and ovary. A flower may have one or multiple carpels. Visual Connection If the anther is missing, what type of reproductive structure will the flower be unable to produce? What term is used to describe an incomplete flower lacking the androecium? What term describes an incomplete flower lacking a gynoecium? If all four whorls (the calyx, corolla, androecium, and gynoecium) are present, the flower is described as complete. If any of the four parts is missing, the flower is known as incomplete. Flowers that contain both an androecium and a gynoecium are called perfect, androgynous or hermaphrodites. There are two types of incomplete flowers: staminate flowers contain only an androecium, and carpellate flowers have only a gynoecium ( Figure 32.4 ). If both male and female flowers are borne on the same plant, the species is called monoecious (meaning “one home”): examples are corn and pea. Species with male and female flowers borne on separate plants are termed dioecious, or “two homes,” examples of which are C. papaya and Cannabis . The ovary, which may contain one or multiple ovules, may be placed above other flower parts, which is referred to as superior; or, it may be placed below the other flower parts, referred to as inferior ( Figure 32.5 ). Male Gametophyte (The Pollen Grain) The male gametophyte develops and reaches maturity in an immature anther. In a plant’s male reproductive organs, development of pollen takes place in a structure known as the microsporangium ( Figure 32.6 ). The microsporangia, which are usually bi-lobed, are pollen sacs in which the microspores develop into pollen grains. These are found in the anther, which is at the end of the stamen—the long filament that supports the anther. Within the microsporangium, the microspore mother cell divides by meiosis to give rise to four microspores, each of which will ultimately form a pollen grain ( Figure 32.7 ). An inner layer of cells, known as the tapetum, provides nutrition to the developing microspores and contributes key components to the pollen wall. Mature pollen grains contain two cells: a generative cell and a pollen tube cell. The generative cell is contained within the larger pollen tube cell. Upon germination, the tube cell forms the pollen tube through which the generative cell migrates to enter the ovary. During its transit inside the pollen tube, the generative cell divides to form two male gametes (sperm cells). Upon maturity, the microsporangia burst, releasing the pollen grains from the anther. Each pollen grain has two coverings: the exine (thicker, outer layer) and the intine ( Figure 32.7 ). The exine contains sporopollenin, a complex waterproofing substance supplied by the tapetal cells. Sporopollenin allows the pollen to survive under unfavorable conditions and to be carried by wind, water, or biological agents without undergoing damage. Female Gametophyte (The Embryo Sac) While the details may vary between species, the overall development of the female gametophyte has two distinct phases. First, in the process of megasporogenesis , a single cell in the diploid megasporangium —an area of tissue in the ovules—undergoes meiosis to produce four megaspores, only one of which survives. During the second phase, megagametogenesis , the surviving haploid megaspore undergoes mitosis to produce an eight-nucleate, seven-cell female gametophyte, also known as the megagametophyte or embryo sac. Two of the nuclei—the polar nuclei —move to the equator and fuse, forming a single, diploid central cell. This central cell later fuses with a sperm to form the triploid endosperm. Three nuclei position themselves on the end of the embryo sac opposite the micropyle and develop into the antipodal cells, which later degenerate. The nucleus closest to the micropyle becomes the female gamete, or egg cell, and the two adjacent nuclei develop into synergid cells ( Figure 32.8 ). The synergids help guide the pollen tube for successful fertilization, after which they disintegrate. Once fertilization is complete, the resulting diploid zygote develops into the embryo, and the fertilized ovule forms the other tissues of the seed. A double-layered integument protects the megasporangium and, later, the embryo sac. The integument will develop into the seed coat after fertilization and protect the entire seed. The ovule wall will become part of the fruit. The integuments, while protecting the megasporangium, do not enclose it completely, but leave an opening called the micropyle . The micropyle allows the pollen tube to enter the female gametophyte for fertilization. Visual Connection An embryo sac is missing the synergids. What specific impact would you expect this to have on fertilization? The pollen tube will be unable to form. The pollen tube will form but will not be guided toward the egg. Fertilization will not occur because the synergid is the egg. Fertilization will occur but the embryo will not be able to grow. Sexual Reproduction in Gymnosperms As with angiosperms, the lifecycle of a gymnosperm is also characterized by alternation of generations. In conifers such as pines, the green leafy part of the plant is the sporophyte, and the cones contain the male and female gametophytes ( Figure 32.9 ). The female cones are larger than the male cones and are positioned towards the top of the tree; the small, male cones are located in the lower region of the tree. Because the pollen is shed and blown by the wind, this arrangement makes it difficult for a gymnosperm to self-pollinate. Male Gametophyte A male cone has a central axis on which bracts, a type of modified leaf, are attached. The bracts are known as microsporophylls ( Figure 32.10 ) and are the sites where microspores will develop. The microspores develop inside the microsporangium. Within the microsporangium, cells known as microsporocytes divide by meiosis to produce four haploid microspores. Further mitosis of the microspore produces two nuclei: the generative nucleus, and the tube nucleus. Upon maturity, the male gametophyte (pollen) is released from the male cones and is carried by the wind to land on the female cone. Link to Learning Watch this video to see a cedar releasing its pollen in the wind. Click to view content Female Gametophyte The female cone also has a central axis on which bracts known as megasporophylls ( Figure 32.10 ) are present. In the female cone, megaspore mother cells are present in the megasporangium. The megaspore mother cell divides by meiosis to produce four haploid megaspores. One of the megaspores divides to form the multicellular female gametophyte, while the others divide to form the rest of the structure. The female gametophyte is contained within a structure called the archegonium. Reproductive Process Upon landing on the female cone, the tube cell of the pollen forms the pollen tube, through which the generative cell migrates towards the female gametophyte through the micropyle. It takes approximately one year for the pollen tube to grow and migrate towards the female gametophyte. The male gametophyte containing the generative cell splits into two sperm nuclei, one of which fuses with the egg, while the other degenerates. After fertilization of the egg, the diploid zygote is formed, which divides by mitosis to form the embryo. The scales of the cones are closed during development of the seed. The seed is covered by a seed coat, which is derived from the female sporophyte. Seed development takes another one to two years. Once the seed is ready to be dispersed, the bracts of the female cones open to allow the dispersal of seed; no fruit formation takes place because gymnosperm seeds have no covering. Angiosperms versus Gymnosperms Gymnosperm reproduction differs from that of angiosperms in several ways ( Figure 32.11 ). In angiosperms, the female gametophyte exists in an enclosed structure—the ovule—which is within the ovary; in gymnosperms, the female gametophyte is present on exposed bracts of the female cone. Double fertilization is a key event in the lifecycle of angiosperms, but is completely absent in gymnosperms. The male and female gametophyte structures are present on separate male and female cones in gymnosperms, whereas in angiosperms, they are a part of the flower. Lastly, wind plays an important role in pollination in gymnosperms because pollen is blown by the wind to land on the female cones. Although many angiosperms are also wind-pollinated, animal pollination is more common. Link to Learning View an animation of the double fertilization process of angiosperms. Click to view content 32.2 Pollination and Fertilization Learning Objectives By the end of this section, you will be able to: Describe what must occur for plant fertilization Explain cross-pollination and the ways in which it takes place Describe the process that leads to the development of a seed Define double fertilization In angiosperms, pollination is defined as the placement or transfer of pollen from the anther to the stigma of the same flower or another flower. In gymnosperms, pollination involves pollen transfer from the male cone to the female cone. Upon transfer, the pollen germinates to form the pollen tube and the sperm for fertilizing the egg. Pollination has been well studied since the time of Gregor Mendel. Mendel successfully carried out self- as well as cross-pollination in garden peas while studying how characteristics were passed on from one generation to the next. Today’s crops are a result of plant breeding, which employs artificial selection to produce the present-day cultivars. A case in point is today's corn, which is a result of years of breeding that started with its ancestor, teosinte. The teosinte that the ancient Mayans originally began cultivating had tiny seeds—vastly different from today’s relatively giant ears of corn. Interestingly, though these two plants appear to be entirely different, the genetic difference between them is miniscule. Pollination takes two forms: self-pollination and cross-pollination. Self-pollination occurs when the pollen from the anther is deposited on the stigma of the same flower, or another flower on the same plant. Cross-pollination is the transfer of pollen from the anther of one flower to the stigma of another flower on a different individual of the same species. Self-pollination occurs in flowers where the stamen and carpel mature at the same time, and are positioned so that the pollen can land on the flower’s stigma. This method of pollination does not require an investment from the plant to provide nectar and pollen as food for pollinators. Link to Learning Explore this interactive website to review self-pollination and cross-pollination. Living species are designed to ensure survival of their progeny; those that fail become extinct. Genetic diversity is therefore required so that in changing environmental or stress conditions, some of the progeny can survive. Self-pollination leads to the production of plants with less genetic diversity, since genetic material from the same plant is used to form gametes, and eventually, the zygote. In contrast, cross-pollination—or out-crossing—leads to greater genetic diversity because the microgametophyte and megagametophyte are derived from different plants. Because cross-pollination allows for more genetic diversity, plants have developed many ways to avoid self-pollination. In some species, the pollen and the ovary mature at different times. These flowers make self-pollination nearly impossible. By the time pollen matures and has been shed, the stigma of this flower is mature and can only be pollinated by pollen from another flower. Some flowers have developed physical features that prevent self-pollination. The primrose is one such flower. Primroses have evolved two flower types with differences in anther and stigma length: the pin-eyed flower has anthers positioned at the pollen tube’s halfway point, and the thrum-eyed flower’s stigma is likewise located at the halfway point. Insects easily cross-pollinate while seeking the nectar at the bottom of the pollen tube. This phenomenon is also known as heterostyly. Many plants, such as cucumber, have male and female flowers located on different parts of the plant, thus making self-pollination difficult. In yet other species, the male and female flowers are borne on different plants (dioecious). All of these are barriers to self-pollination; therefore, the plants depend on pollinators to transfer pollen. The majority of pollinators are biotic agents such as insects (like bees, flies, and butterflies), bats, birds, and other animals. Other plant species are pollinated by abiotic agents, such as wind and water. Everyday Connection Incompatibility Genes in Flowers In recent decades, incompatibility genes—which prevent pollen from germinating or growing into the stigma of a flower—have been discovered in many angiosperm species. If plants do not have compatible genes, the pollen tube stops growing. Self-incompatibility is controlled by the S (sterility) locus. Pollen tubes have to grow through the tissue of the stigma and style before they can enter the ovule. The carpel is selective in the type of pollen it allows to grow inside. The interaction is primarily between the pollen and the stigma epidermal cells. In some plants, like cabbage, the pollen is rejected at the surface of the stigma, and the unwanted pollen does not germinate. In other plants, pollen tube germination is arrested after growing one-third the length of the style, leading to pollen tube death. Pollen tube death is due either to apoptosis (programmed cell death) or to degradation of pollen tube RNA. The degradation results from the activity of a ribonuclease encoded by the S locus. The ribonuclease is secreted from the cells of the style in the extracellular matrix, which lies alongside the growing pollen tube. In summary, self-incompatibility is a mechanism that prevents self-fertilization in many flowering plant species. The working of this self-incompatibility mechanism has important consequences for plant breeders because it inhibits the production of inbred and hybrid plants. Pollination by Insects Bees are perhaps the most important pollinator of many garden plants and most commercial fruit trees ( Figure 32.12 ). The most common species of bees are bumblebees and honeybees. Since bees cannot see the color red, bee-pollinated flowers usually have shades of blue, yellow, or other colors. Bees collect energy-rich pollen or nectar for their survival and energy needs. They visit flowers that are open during the day, are brightly colored, have a strong aroma or scent, and have a tubular shape, typically with the presence of a nectar guide. A nectar guide includes regions on the flower petals that are visible only to bees, and not to humans; it helps to guide bees to the center of the flower, thus making the pollination process more efficient. The pollen sticks to the bees’ fuzzy hair, and when the bee visits another flower, some of the pollen is transferred to the second flower. Recently, there have been many reports about the declining population of honeybees. Many flowers will remain unpollinated and not bear seed if honeybees disappear. The impact on commercial fruit growers could be devastating. Many flies are attracted to flowers that have a decaying smell or an odor of rotting flesh. These flowers, which produce nectar, usually have dull colors, such as brown or purple. They are found on the corpse flower or voodoo lily ( Amorphophallus ), dragon arum ( Dracunculus ), and carrion flower ( Stapleia , Rafflesia ). The nectar provides energy, whereas the pollen provides protein. Wasps are also important insect pollinators, and pollinate many species of figs. Butterflies, such as the monarch, pollinate many garden flowers and wildflowers, which usually occur in clusters. These flowers are brightly colored, have a strong fragrance, are open during the day, and have nectar guides to make access to nectar easier. The pollen is picked up and carried on the butterfly’s limbs. Moths, on the other hand, pollinate flowers during the late afternoon and night. The flowers pollinated by moths are pale or white and are flat, enabling the moths to land. One well-studied example of a moth-pollinated plant is the yucca plant, which is pollinated by the yucca moth. The shape of the flower and moth have adapted in such a way as to allow successful pollination. The moth deposits pollen on the sticky stigma for fertilization to occur later. The female moth also deposits eggs into the ovary. As the eggs develop into larvae, they obtain food from the flower and developing seeds. Thus, both the insect and flower benefit from each other in this symbiotic relationship. The corn earworm moth and Gaura plant have a similar relationship ( Figure 32.13 ). Pollination by Bats In the tropics and deserts, bats are often the pollinators of nocturnal flowers such as agave, guava, and morning glory. The flowers are usually large and white or pale-colored; thus, they can be distinguished from the dark surroundings at night. The flowers have a strong, fruity, or musky fragrance and produce large amounts of nectar. They are naturally large and wide-mouthed to accommodate the head of the bat. As the bats seek the nectar, their faces and heads become covered with pollen, which is then transferred to the next flower. Pollination by Birds Many species of small birds, such as the hummingbird ( Figure 32.14 ) and sun birds, are pollinators for plants such as orchids and other wildflowers. Flowers visited by birds are usually sturdy and are oriented in such a way as to allow the birds to stay near the flower without getting their wings entangled in the nearby flowers. The flower typically has a curved, tubular shape, which allows access for the bird’s beak. Brightly colored, odorless flowers that are open during the day are pollinated by birds. As a bird seeks energy-rich nectar, pollen is deposited on the bird’s head and neck and is then transferred to the next flower it visits. Botanists have been known to determine the range of extinct plants by collecting and identifying pollen from 200-year-old bird specimens from the same site. Pollination by Wind Most species of conifers, and many angiosperms, such as grasses, maples and oaks, are pollinated by wind. Pine cones are brown and unscented, while the flowers of wind-pollinated angiosperm species are usually green, small, may have small or no petals, and produce large amounts of pollen. Unlike the typical insect-pollinated flowers, flowers adapted to pollination by wind do not produce nectar or scent. In wind-pollinated species, the microsporangia hang out of the flower, and, as the wind blows, the lightweight pollen is carried with it ( Figure 32.15 ). The flowers usually emerge early in the spring, before the leaves, so that the leaves do not block the movement of the wind. The pollen is deposited on the exposed feathery stigma of the flower ( Figure 32.16 ). Pollination by Water Some weeds, such as Australian sea grass and pond weeds, are pollinated by water. The pollen floats on water, and when it comes into contact with the flower, it is deposited inside the flower. Evolution Connection Pollination by Deception Orchids are highly valued flowers, with many rare varieties ( Figure 32.17 ). They grow in a range of specific habitats, mainly in the tropics of Asia, South America, and Central America. At least 25,000 species of orchids have been identified. Flowers often attract pollinators with food rewards, in the form of nectar. However, some species of orchid are an exception to this standard: they have evolved different ways to attract the desired pollinators. They use a method known as food deception, in which bright colors and perfumes are offered, but no food. Anacamptis morio , commonly known as the green-winged orchid, bears bright purple flowers and emits a strong scent. The bumblebee, its main pollinator, is attracted to the flower because of the strong scent—which usually indicates food for a bee—and in the process, picks up the pollen to be transported to another flower. Other orchids use sexual deception. Chiloglottis trapeziformis emits a compound that smells the same as the pheromone emitted by a female wasp to attract male wasps. The male wasp is attracted to the scent, lands on the orchid flower, and in the process, transfers pollen. Some orchids, like the Australian hammer orchid, use scent as well as visual trickery in yet another sexual deception strategy to attract wasps. The flower of this orchid mimics the appearance of a female wasp and emits a pheromone. The male wasp tries to mate with what appears to be a female wasp, and in the process, picks up pollen, which it then transfers to the next counterfeit mate. Double Fertilization After pollen is deposited on the stigma, it must germinate and grow through the style to reach the ovule. The microspores, or the pollen, contain two cells: the pollen tube cell and the generative cell. The pollen tube cell grows into a pollen tube through which the generative cell travels. The germination of the pollen tube requires water, oxygen, and certain chemical signals. As it travels through the style to reach the embryo sac, the pollen tube’s growth is supported by the tissues of the style. In the meantime, if the generative cell has not already split into two cells, it now divides to form two sperm cells. The pollen tube is guided by the chemicals secreted by the synergids present in the embryo sac, and it enters the ovule sac through the micropyle. Of the two sperm cells, one sperm fertilizes the egg cell, forming a diploid zygote; the other sperm fuses with the two polar nuclei, forming a triploid cell that develops into the endosperm . Together, these two fertilization events in angiosperms are known as double fertilization ( Figure 32.18 ). After fertilization is complete, no other sperm can enter. The fertilized ovule forms the seed, whereas the tissues of the ovary become the fruit, usually enveloping the seed. After fertilization, the zygote divides to form two cells: the upper cell, or terminal cell, and the lower, or basal, cell. The division of the basal cell gives rise to the suspensor , which eventually makes connection with the maternal tissue. The suspensor provides a route for nutrition to be transported from the mother plant to the growing embryo. The terminal cell also divides, giving rise to a globular-shaped proembryo ( Figure 32.19 a ). In dicots (eudicots), the developing embryo has a heart shape, due to the presence of the two rudimentary cotyledons ( Figure 32.19 b ). In non-endospermic dicots, such as Capsella bursa , the endosperm develops initially, but is then digested, and the food reserves are moved into the two cotyledons. As the embryo and cotyledons enlarge, they run out of room inside the developing seed, and are forced to bend ( Figure 32.19 c ). Ultimately, the embryo and cotyledons fill the seed ( Figure 32.19 d ), and the seed is ready for dispersal. Embryonic development is suspended after some time, and growth is resumed only when the seed germinates. The developing seedling will rely on the food reserves stored in the cotyledons until the first set of leaves begin photosynthesis. Development of the Seed The mature ovule develops into the seed. A typical seed contains a seed coat, cotyledons, endosperm, and a single embryo ( Figure 32.20 ). Visual Connection What is of the following statements is true? Both monocots and dicots have an endosperm. The radicle develops into the root. The plumule is part of the epicotyl The endosperm is part of the embryo. The storage of food reserves in angiosperm seeds differs between monocots and dicots. In monocots, such as corn and wheat, the single cotyledon is called a scutellum ; the scutellum is connected directly to the embryo via vascular tissue (xylem and phloem). Food reserves are stored in the large endosperm. Upon germination, enzymes are secreted by the aleurone , a single layer of cells just inside the seed coat that surrounds the endosperm and embryo. The enzymes degrade the stored carbohydrates, proteins and lipids, the products of which are absorbed by the scutellum and transported via a vasculature strand to the developing embryo. Therefore, the scutellum can be seen to be an absorptive organ, not a storage organ. The two cotyledons in the dicot seed also have vascular connections to the embryo. In endospermic dicots , the food reserves are stored in the endosperm. During germination, the two cotyledons therefore act as absorptive organs to take up the enzymatically released food reserves, much like in monocots (monocots, by definition, also have endospermic seeds). Tobacco ( Nicotiana tabaccum ), tomato ( Solanum lycopersicum ), and pepper ( Capsicum annuum ) are examples of endospermic dicots. In non-endospermic dicots , the triploid endosperm develops normally following double fertilization, but the endosperm food reserves are quickly remobilized and moved into the developing cotyledon for storage. The two halves of a peanut seed ( Arachis hypogaea ) and the split peas ( Pisum sativum ) of split pea soup are individual cotyledons loaded with food reserves. The seed, along with the ovule, is protected by a seed coat that is formed from the integuments of the ovule sac. In dicots, the seed coat is further divided into an outer coat known as the testa and inner coat known as the tegmen . The embryonic axis consists of three parts: the plumule, the radicle, and the hypocotyl. The portion of the embryo between the cotyledon attachment point and the radicle is known as the hypocotyl (hypocotyl means “below the cotyledons”). The embryonic axis terminates in a radicle (the embryonic root), which is the region from which the root will develop. In dicots, the hypocotyls extend above ground, giving rise to the stem of the plant. In monocots, the hypocotyl does not show above ground because monocots do not exhibit stem elongation. The part of the embryonic axis that projects above the cotyledons is known as the epicotyl . The plumule is composed of the epicotyl, young leaves, and the shoot apical meristem. Upon germination in dicot seeds, the epicotyl is shaped like a hook with the plumule pointing downwards. This shape is called the plumule hook, and it persists as long as germination proceeds in the dark. Therefore, as the epicotyl pushes through the tough and abrasive soil, the plumule is protected from damage. Upon exposure to light, the hypocotyl hook straightens out, the young foliage leaves face the sun and expand, and the epicotyl continues to elongate. During this time, the radicle is also growing and producing the primary root. As it grows downward to form the tap root, lateral roots branch off to all sides, producing the typical dicot tap root system. In monocot seeds ( Figure 32.21 ), the testa and tegmen of the seed coat are fused. As the seed germinates, the primary root emerges, protected by the root-tip covering: the coleorhiza . Next, the primary shoot emerges, protected by the coleoptile : the covering of the shoot tip. Upon exposure to light (i.e. when the plumule has exited the soil and the protective coleoptile is no longer needed), elongation of the coleoptile ceases and the leaves expand and unfold. At the other end of the embryonic axis, the primary root soon dies, while other, adventitious roots (roots that do not arise from the usual place – i.e. the root) emerge from the base of the stem. This gives the monocot a fibrous root system. Seed Germination Many mature seeds enter a period of inactivity, or extremely low metabolic activity: a process known as dormancy , which may last for months, years or even centuries. Dormancy helps keep seeds viable during unfavorable conditions. Upon a return to favorable conditions, seed germination takes place. Favorable conditions could be as diverse as moisture, light, cold, fire, or chemical treatments. After heavy rains, many new seedlings emerge. Forest fires also lead to the emergence of new seedlings. Some seeds require vernalization (cold treatment) before they can germinate. This guarantees that seeds produced by plants in temperate climates will not germinate until the spring. Plants growing in hot climates may have seeds that need a heat treatment in order to germinate, to avoid germination in the hot, dry summers. In many seeds, the presence of a thick seed coat retards the ability to germinate. Scarification , which includes mechanical or chemical processes to soften the seed coat, is often employed before germination. Presoaking in hot water, or passing through an acid environment, such as an animal’s digestive tract, may also be employed. Depending on seed size, the time taken for a seedling to emerge may vary. Species with large seeds have enough food reserves to germinate deep below ground, and still extend their epicotyl all the way to the soil surface. Seeds of small-seeded species usually require light as a germination cue. This ensures the seeds only germinate at or near the soil surface (where the light is greatest). If they were to germinate too far underneath the surface, the developing seedling would not have enough food reserves to reach the sunlight. Development of Fruit and Fruit Types After fertilization, the ovary of the flower usually develops into the fruit. Fruits are usually associated with having a sweet taste; however, not all fruits are sweet. Botanically, the term “fruit” is used for a ripened ovary. In most cases, flowers in which fertilization has taken place will develop into fruits, and flowers in which fertilization has not taken place will not. Some fruits develop from the ovary and are known as true fruits, whereas others develop from other parts of the female gametophyte and are known as accessory fruits. The fruit encloses the seeds and the developing embryo, thereby providing it with protection. Fruits are of many types, depending on their origin and texture. The sweet tissue of the blackberry, the red flesh of the tomato, the shell of the peanut, and the hull of corn (the tough, thin part that gets stuck in your teeth when you eat popcorn) are all fruits. As the fruit matures, the seeds also mature. Fruits may be classified as simple, aggregate, multiple, or accessory, depending on their origin ( Figure 32.22 ). If the fruit develops from a single carpel or fused carpels of a single ovary, it is known as a simple fruit , as seen in nuts and beans. An aggregate fruit is one that develops from more than one carpel, but all are in the same flower: the mature carpels fuse together to form the entire fruit, as seen in the raspberry. Multiple fruit develops from an inflorescence or a cluster of flowers. An example is the pineapple, where the flowers fuse together to form the fruit. Accessory fruits (sometimes called false fruits) are not derived from the ovary, but from another part of the flower, such as the receptacle (strawberry) or the hypanthium (apples and pears). Fruits generally have three parts: the exocarp (the outermost skin or covering), the mesocarp (middle part of the fruit), and the endocarp (the inner part of the fruit). Together, all three are known as the pericarp . The mesocarp is usually the fleshy, edible part of the fruit; however, in some fruits, such as the almond, the endocarp is the edible part. In many fruits, two or all three of the layers are fused, and are indistinguishable at maturity. Fruits can be dry or fleshy. Furthermore, fruits can be divided into dehiscent or indehiscent types. Dehiscent fruits, such as peas, readily release their seeds, while indehiscent fruits, like peaches, rely on decay to release their seeds. Fruit and Seed Dispersal The fruit has a single purpose: seed dispersal. Seeds contained within fruits need to be dispersed far from the mother plant, so they may find favorable and less competitive conditions in which to germinate and grow. Some fruit have built-in mechanisms so they can disperse by themselves, whereas others require the help of agents like wind, water, and animals ( Figure 32.23 ). Modifications in seed structure, composition, and size help in dispersal. Wind-dispersed fruit are lightweight and may have wing-like appendages that allow them to be carried by the wind. Some have a parachute-like structure to keep them afloat. Some fruits—for example, the dandelion—have hairy, weightless structures that are suited to dispersal by wind. Seeds dispersed by water are contained in light and buoyant fruit, giving them the ability to float. Coconuts are well known for their ability to float on water to reach land where they can germinate. Similarly, willow and silver birches produce lightweight fruit that can float on water. Animals and birds eat fruits, and the seeds that are not digested are excreted in their droppings some distance away. Some animals, like squirrels, bury seed-containing fruits for later use; if the squirrel does not find its stash of fruit, and if conditions are favorable, the seeds germinate. Some fruits, like the cocklebur, have hooks or sticky structures that stick to an animal's coat and are then transported to another place. Humans also play a big role in dispersing seeds when they carry fruits to new places and throw away the inedible part that contains the seeds. All of the above mechanisms allow for seeds to be dispersed through space, much like an animal’s offspring can move to a new location. Seed dormancy, which was described earlier, allows plants to disperse their progeny through time: something animals cannot do. Dormant seeds can wait months, years, or even decades for the proper conditions for germination and propagation of the species. 32.3 Asexual Reproduction Learning Objectives By the end of this section, you will be able to: Compare the mechanisms and methods of natural and artificial asexual reproduction Describe the advantages and disadvantages of natural and artificial asexual reproduction Discuss plant life spans Many plants are able to propagate themselves using asexual reproduction. This method does not require the investment required to produce a flower, attract pollinators, or find a means of seed dispersal. Asexual reproduction produces plants that are genetically identical to the parent plant because no mixing of male and female gametes takes place. Traditionally, these plants survive well under stable environmental conditions when compared with plants produced from sexual reproduction because they carry genes identical to those of their parents. Many different types of roots exhibit asexual reproduction Figure 32.24 . The corm is used by gladiolus and garlic. Bulbs, such as a scaly bulb in lilies and a tunicate bulb in daffodils, are other common examples. A potato is a stem tuber, while parsnip propagates from a taproot. Ginger and iris produce rhizomes, while ivy uses an adventitious root (a root arising from a plant part other than the main or primary root), and the strawberry plant has a stolon, which is also called a runner. Some plants can produce seeds without fertilization. Either the ovule or part of the ovary, which is diploid in nature, gives rise to a new seed. This method of reproduction is known as apomixis . An advantage of asexual reproduction is that the resulting plant will reach maturity faster. Since the new plant is arising from an adult plant or plant parts, it will also be sturdier than a seedling. Asexual reproduction can take place by natural or artificial (assisted by humans) means. Natural Methods of Asexual Reproduction Natural methods of asexual reproduction include strategies that plants have developed to self-propagate. Many plants—like ginger, onion, gladioli, and dahlia—continue to grow from buds that are present on the surface of the stem. In some plants, such as the sweet potato, adventitious roots or runners can give rise to new plants Figure 32.25 . In Bryophyllum and kalanchoe, the leaves have small buds on their margins. When these are detached from the plant, they grow into independent plants; or, they may start growing into independent plants if the leaf touches the soil. Some plants can be propagated through cuttings alone. Artificial Methods of Asexual Reproduction These methods are frequently employed to give rise to new, and sometimes novel, plants. They include grafting, cutting, layering, and micropropagation. Grafting Grafting has long been used to produce novel varieties of roses, citrus species, and other plants. In grafting , two plant species are used; part of the stem of the desirable plant is grafted onto a rooted plant called the stock. The part that is grafted or attached is called the scion . Both are cut at an oblique angle (any angle other than a right angle), placed in close contact with each other, and are then held together Figure 32.26 . Matching up these two surfaces as closely as possible is extremely important because these will be holding the plant together. The vascular systems of the two plants grow and fuse, forming a graft. After a period of time, the scion starts producing shoots, and eventually starts bearing flowers and fruits. Grafting is widely used in viticulture (grape growing) and the citrus industry. Scions capable of producing a particular fruit variety are grated onto root stock with specific resistance to disease. Cutting Plants such as coleus and money plant are propagated through stem cuttings , where a portion of the stem containing nodes and internodes is placed in moist soil and allowed to root. In some species, stems can start producing a root even when placed only in water. For example, leaves of the African violet will root if kept in water undisturbed for several weeks. Layering Layering is a method in which a stem attached to the plant is bent and covered with soil. Young stems that can be bent easily without any injury are preferred. Jasmine and bougainvillea (paper flower) can be propagated this way Figure 32.27 . In some plants, a modified form of layering known as air layering is employed. A portion of the bark or outermost covering of the stem is removed and covered with moss, which is then taped. Some gardeners also apply rooting hormone. After some time, roots will appear, and this portion of the plant can be removed and transplanted into a separate pot. Micropropagation Micropropagation (also called plant tissue culture) is a method of propagating a large number of plants from a single plant in a short time under laboratory conditions Figure 32.28 . This method allows propagation of rare, endangered species that may be difficult to grow under natural conditions, are economically important, or are in demand as disease-free plants. To start plant tissue culture, a part of the plant such as a stem, leaf, embryo, anther, or seed can be used. The plant material is thoroughly sterilized using a combination of chemical treatments standardized for that species. Under sterile conditions, the plant material is placed on a plant tissue culture medium that contains all the minerals, vitamins, and hormones required by the plant. The plant part often gives rise to an undifferentiated mass known as callus, from which individual plantlets begin to grow after a period of time. These can be separated and are first grown under greenhouse conditions before they are moved to field conditions. Plant Life Spans The length of time from the beginning of development to the death of a plant is called its life span. The life cycle, on the other hand, is the sequence of stages a plant goes through from seed germination to seed production of the mature plant. Some plants, such as annuals, only need a few weeks to grow, produce seeds and die. Other plants, such as the bristlecone pine, live for thousands of years. Some bristlecone pines have a documented age of 4,500 years Figure 32.29 . Even as some parts of a plant, such as regions containing meristematic tissue—the area of active plant growth consisting of undifferentiated cells capable of cell division—continue to grow, some parts undergo programmed cell death (apoptosis). The cork found on stems, and the water-conducting tissue of the xylem, for example, are composed of dead cells. Plant species that complete their lifecycle in one season are known as annuals, an example of which is Arabidopsis , or mouse-ear cress. Biennials such as carrots complete their lifecycle in two seasons. In a biennial’s first season, the plant has a vegetative phase, whereas in the next season, it completes its reproductive phase. Commercial growers harvest the carrot roots after the first year of growth, and do not allow the plants to flower. Perennials, such as the magnolia, complete their lifecycle in two years or more. In another classification based on flowering frequency, monocarpic plants flower only once in their lifetime; examples include bamboo and yucca. During the vegetative period of their life cycle (which may be as long as 120 years in some bamboo species), these plants may reproduce asexually and accumulate a great deal of food material that will be required during their once-in-a-lifetime flowering and setting of seed after fertilization. Soon after flowering, these plants die. Polycarpic plants form flowers many times during their lifetime. Fruit trees, such as apple and orange trees, are polycarpic; they flower every year. Other polycarpic species, such as perennials, flower several times during their life span, but not each year. By this means, the plant does not require all its nutrients to be channelled towards flowering each year. As is the case with all living organisms, genetics and environmental conditions have a role to play in determining how long a plant will live. Susceptibility to disease, changing environmental conditions, drought, cold, and competition for nutrients are some of the factors that determine the survival of a plant. Plants continue to grow, despite the presence of dead tissue such as cork. Individual parts of plants, such as flowers and leaves, have different rates of survival. In many trees, the older leaves turn yellow and eventually fall from the tree. Leaf fall is triggered by factors such as a decrease in photosynthetic efficiency, due to shading by upper leaves, or oxidative damage incurred as a result of photosynthetic reactions. The components of the part to be shed are recycled by the plant for use in other processes, such as development of seed and storage. This process is known as nutrient recycling. The aging of a plant and all the associated processes is known as senescence , which is marked by several complex biochemical changes. One of the characteristics of senescence is the breakdown of chloroplasts, which is characterized by the yellowing of leaves. The chloroplasts contain components of photosynthetic machinery such as membranes and proteins. Chloroplasts also contain DNA. The proteins, lipids, and nucleic acids are broken down by specific enzymes into smaller molecules and salvaged by the plant to support the growth of other plant tissues. The complex pathways of nutrient recycling within a plant are not well understood. Hormones are known to play a role in senescence. Applications of cytokinins and ethylene delay or prevent senescence; in contrast, abscissic acid causes premature onset of senescence.
biology
Chapter Outline 23.1 Eukaryotic Origins 23.2 Characteristics of Protists 23.3 Groups of Protists 23.4 Ecology of Protists Introduction Humans have been familiar with macroscopic organisms (organisms big enough to see with the unaided eye) since before there was a written history, and it is likely that most cultures distinguished between animals and land plants, and most probably included the macroscopic fungi as plants. Therefore, it became an interesting challenge to deal with the world of microorganisms once microscopes were developed a few centuries ago. Many different naming schemes were used over the last couple of centuries, but it has become the most common practice to refer to eukaryotes that are not land plants, animals, or fungi as protists. This name was first suggested by Ernst Haeckel in the late nineteenth century. It has been applied in many contexts and has been formally used to represent a kingdom-level taxon called Protista. However, many modern systematists (biologists who study the relationships among organisms) are beginning to shy away from the idea of formal ranks such as kingdom and phylum. Instead, they are naming taxa as groups of organisms thought to include all the descendants of a last common ancestor (monophyletic group). During the past two decades, the field of molecular genetics has demonstrated that some protists are more related to animals, plants, or fungi than they are to other protists. Therefore, not including animals, plants and fungi make the kingdom Protista a paraphyletic group, or one that does not include all descendents of its common ancestor. For this reason, protist lineages originally classified into the kingdom Protista continue to be examined and debated. In the meantime, the term “protist” still is used informally to describe this tremendously diverse group of eukaryotes. Most protists are microscopic, unicellular organisms that are abundant in soil, freshwater, brackish, and marine environments. They are also common in the digestive tracts of animals and in the vascular tissues of plants. Others invade the cells of other protists, animals, and plants. Not all protists are microscopic. Some have huge, macroscopic cells, such as the plasmodia (giant amoebae) of myxomycete slime molds or the marine green alga Caulerpa , which can have single cells that can be several meters in size. Some protists are multicellular, such as the red, green, and brown seaweeds. It is among the protists that one finds the wealth of ways that organisms can grow.
[ { "answer": { "ans_choice": 3, "ans_text": "oxygenation of the atmosphere" }, "bloom": "3", "hl_context": "<hl> Recall that the first fossils that we believe to be eukaryotes date to about 2 billion years old , so they appeared as oxygen levels were increasing . <hl> Also , recall that all extant eukaryotes descended from an ancestor with mitochondria . These organelles were first observed by light microscopists in the late 1800s , where they appeared to be somewhat worm-shaped structures that seemed to be moving around in the cell . Some early observers suggested that they might be bacteria living inside host cells , but these hypotheses remained unknown or rejected in most scientific communities .", "hl_sentences": "Recall that the first fossils that we believe to be eukaryotes date to about 2 billion years old , so they appeared as oxygen levels were increasing .", "question": { "cloze_format": "The event that is thought to have contributed to the evolution of eukaryotes is ___.", "normal_format": "What event is thought to have contributed to the evolution of eukaryotes?", "question_choices": [ "global warming", "glaciation", "volcanic activity", "oxygenation of the atmosphere" ], "question_id": "fs-idp86366592", "question_text": "What event is thought to have contributed to the evolution of eukaryotes?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 2, "ans_text": "DNA-based genome" }, "bloom": "2", "hl_context": "<hl> Mitochondria that carry out aerobic respiration have their own genomes , with genes similar to those in alpha-proteobacteria . <hl> However , many of the genes for respiratory proteins are located in the nucleus . When these genes are compared to those of other organisms , they appear to be of alpha-proteobacterial origin . <hl> Additionally , in some eukaryotic groups , such genes are found in the mitochondria , whereas in other groups , they are found in the nucleus . <hl> <hl> This has been interpreted as evidence that genes have been transferred from the endosymbiont chromosome to the host genome . <hl> This loss of genes by the endosymbiont is probably one explanation why mitochondria cannot live without a host . <hl> One of the major features distinguishing prokaryotes from eukaryotes is the presence of mitochondria . <hl> Eukaryotic cells may contain anywhere from one to several thousand mitochondria , depending on the cell ’ s level of energy consumption . Each mitochondrion measures 1 to 10 or greater micrometers in length and exists in the cell as an organelle that can be ovoid to worm-shaped to intricately branched ( Figure 23.2 ) . Mitochondria arise from the division of existing mitochondria ; they may fuse together ; and they may be moved around inside the cell by interactions with the cytoskeleton . However , mitochondria cannot survive outside the cell . As the atmosphere was oxygenated by photosynthesis , and as successful aerobic prokaryotes evolved , evidence suggests that an ancestral cell with some membrane compartmentalization engulfed a free-living aerobic prokaryote , specifically an alpha-proteobacterium , thereby giving the host cell the ability to use oxygen to release energy stored in nutrients . Alpha-proteobacteria are a large group of bacteria that includes species symbiotic with plants , disease organisms that can infect humans via ticks , and many free-living species that use light for energy . Several lines of evidence support that mitochondria are derived from this endosymbiotic event . Most mitochondria are shaped like alpha-proteobacteria and are surrounded by two membranes . The mitochondrial inner membrane is extensive and involves substantial infoldings called cristae that resemble the textured , outer surface of alpha-proteobacteria . The matrix and inner membrane are rich with the enzymes necessary for aerobic respiration . Mitochondria divide independently by a process that resembles binary fission in prokaryotes . Specifically , mitochondria are not formed from scratch ( de novo ) by the eukaryotic cell ; they reproduce within it and are distributed with the cytoplasm when a cell divides or two cells fuse . Therefore , although these organelles are highly integrated into the eukaryotic cell , they still reproduce as if they are independent organisms within the cell . However , their reproduction is synchronized with the activity and division of the cell . Mitochondria have their own ( usually ) circular DNA chromosome that is stabilized by attachments to the inner membrane and carries genes similar to genes expressed by alpha-proteobacteria . Mitochondria also have special ribosomes and transfer RNAs that resemble these components in prokaryotes . These features all support that mitochondria were once free-living prokaryotes . <hl> A cytoskeleton containing the structural and motility components called actin microfilaments and microtubules . <hl> <hl> All extant eukaryotes have these cytoskeletal elements . <hl> <hl> Cells with nuclei surrounded by a nuclear envelope with nuclear pores . <hl> <hl> This is the single characteristic that is both necessary and sufficient to define an organism as a eukaryote . <hl> All extant eukaryotes have cells with nuclei .", "hl_sentences": "Mitochondria that carry out aerobic respiration have their own genomes , with genes similar to those in alpha-proteobacteria . Additionally , in some eukaryotic groups , such genes are found in the mitochondria , whereas in other groups , they are found in the nucleus . This has been interpreted as evidence that genes have been transferred from the endosymbiont chromosome to the host genome . One of the major features distinguishing prokaryotes from eukaryotes is the presence of mitochondria . A cytoskeleton containing the structural and motility components called actin microfilaments and microtubules . All extant eukaryotes have these cytoskeletal elements . Cells with nuclei surrounded by a nuclear envelope with nuclear pores . This is the single characteristic that is both necessary and sufficient to define an organism as a eukaryote .", "question": { "cloze_format": "The characteristic that is shared by prokaryotes and eukaryotes is the ___.", "normal_format": "Which characteristic is shared by prokaryotes and eukaryotes?", "question_choices": [ "cytoskeleton", "nuclear envelope", "DNA-based genome", "mitochondria" ], "question_id": "fs-idp48251952", "question_text": "Which characteristic is shared by prokaryotes and eukaryotes?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 2, "ans_text": "endosymbiosis" }, "bloom": null, "hl_context": "<hl> Like mitochondria , plastids appear to have an endosymbiotic origin . <hl> <hl> This hypothesis was also championed by Lynn Margulis . <hl> <hl> Plastids are derived from cyanobacteria that lived inside the cells of an ancestral , aerobic , heterotrophic eukaryote . <hl> <hl> This is called primary endosymbiosis , and plastids of primary origin are surrounded by two membranes . <hl> The best evidence is that this has happened twice in the history of eukaryotes . In one case , the common ancestor of the major lineage / supergroup Archaeplastida took on a cyanobacterial endosymbiont ; in the other , the ancestor of the small amoeboid rhizarian taxon , Paulinella , took on a different cyanobacterial endosymbiont . Almost all photosynthetic eukaryotes are descended from the first event , and only a couple of species are derived from the other .", "hl_sentences": "Like mitochondria , plastids appear to have an endosymbiotic origin . This hypothesis was also championed by Lynn Margulis . Plastids are derived from cyanobacteria that lived inside the cells of an ancestral , aerobic , heterotrophic eukaryote . This is called primary endosymbiosis , and plastids of primary origin are surrounded by two membranes .", "question": { "cloze_format": "Mitochondria most likely evolved by _____________.", "normal_format": "What is mitochondria most likely evolved by?", "question_choices": [ "a photosynthetic cyanobacterium", "cytoskeletal elements", "endosymbiosis", "membrane proliferation" ], "question_id": "fs-idm128928", "question_text": "Mitochondria most likely evolved by _____________." }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 3, "ans_text": "chlorarachniophytes" }, "bloom": "2", "hl_context": "<hl> Several lines of evidence support that chlorarachniophytes evolved from secondary endosymbiosis . <hl> <hl> The chloroplasts contained within the green algal endosymbionts still are capable of photosynthesis , making chlorarachniophytes photosynthetic . <hl> The green algal endosymbiont also exhibits a stunted vestigial nucleus . In fact , it appears that chlorarachniophytes are the products of an evolutionarily recent secondary endosymbiotic event . The plastids of chlorarachniophytes are surrounded by four membranes : The first two correspond to the inner and outer membranes of the photosynthetic cyanobacterium , the third corresponds to the green alga , and the fourth corresponds to the vacuole that surrounded the green alga when it was engulfed by the chlorarachniophyte ancestor . In other lineages that involved secondary endosymbiosis , only three membranes can be identified around plastids . This is currently rectified as a sequential loss of a membrane during the course of evolution .", "hl_sentences": "Several lines of evidence support that chlorarachniophytes evolved from secondary endosymbiosis . The chloroplasts contained within the green algal endosymbionts still are capable of photosynthesis , making chlorarachniophytes photosynthetic .", "question": { "cloze_format": "The protist that is believed to have evolved following a secondary endosymbiosis is ___.", "normal_format": "Which of these protists is believed to have evolved following a secondary endosymbiosis?", "question_choices": [ "green algae", "cyanobacteria", "red algae", "chlorarachniophytes" ], "question_id": "fs-idp17275648", "question_text": "Which of these protists is believed to have evolved following a secondary endosymbiosis?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 3, "ans_text": "proteins" }, "bloom": null, "hl_context": "Single protist cells range in size from less than a micrometer to three meters in length to hectares . <hl> Protist cells may be enveloped by animal-like cell membranes or plant-like cell walls . <hl> <hl> Others are encased in glassy silica-based shells or wound with pellicles of interlocking protein strips . <hl> <hl> The pellicle functions like a flexible coat of armor , preventing the protist from being torn or pierced without compromising its range of motion . <hl>", "hl_sentences": "Protist cells may be enveloped by animal-like cell membranes or plant-like cell walls . Others are encased in glassy silica-based shells or wound with pellicles of interlocking protein strips . The pellicle functions like a flexible coat of armor , preventing the protist from being torn or pierced without compromising its range of motion .", "question": { "cloze_format": "Protists that have a pellicle are surrounded by ______________.", "normal_format": "Protists that have a pellicle are surrounded by which of the following?", "question_choices": [ "silica dioxide", "calcium carbonate", "carbohydrates", "proteins" ], "question_id": "fs-idp161765440", "question_text": "Protists that have a pellicle are surrounded by ______________." }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 1, "ans_text": "mixotrophs" }, "bloom": null, "hl_context": "Protists exhibit many forms of nutrition and may be aerobic or anaerobic . Protists that store energy by photosynthesis belong to a group of photoautotrophs and are characterized by the presence of chloroplasts . Other protists are heterotrophic and consume organic materials ( such as other organisms ) to obtain nutrition . Amoebas and some other heterotrophic protist species ingest particles by a process called phagocytosis , in which the cell membrane engulfs a food particle and brings it inward , pinching off an intracellular membranous sac , or vesicle , called a food vacuole ( Figure 23.7 ) . The vesicle containing the ingested particle , the phagosome , then fuses with a lysosome containing hydrolytic enzymes to produce a phagolysosome , and the food particle is broken down into small molecules that can diffuse into the cytoplasm and be used in cellular metabolism . Undigested remains ultimately are expelled from the cell via exocytosis . <hl> Subtypes of heterotrophs , called saprobes , absorb nutrients from dead organisms or their organic wastes . <hl> <hl> Some protists can function as mixotrophs , obtaining nutrition by photoautotrophic or heterotrophic routes , depending on whether sunlight or organic nutrients are available . <hl>", "hl_sentences": "Subtypes of heterotrophs , called saprobes , absorb nutrients from dead organisms or their organic wastes . Some protists can function as mixotrophs , obtaining nutrition by photoautotrophic or heterotrophic routes , depending on whether sunlight or organic nutrients are available .", "question": { "cloze_format": "Protists with the capabilities to perform photosynthesis and to absorb nutrients from dead organisms are called ______________.", "normal_format": "What are called protists with the capabilities to perform photosynthesis and to absorb nutrients from dead organisms?", "question_choices": [ "photoautotrophs", "mixotrophs", "saprobes", "heterotrophs" ], "question_id": "fs-idp237302288", "question_text": "Protists with the capabilities to perform photosynthesis and to absorb nutrients from dead organisms are called ______________." }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 2, "ans_text": "Both the haploid and diploid forms can be multicellular." }, "bloom": "3", "hl_context": "Like diatoms , golden algae are largely unicellular , although some species can form large colonies . Their characteristic gold color results from their extensive use of carotenoids , a group of photosynthetic pigments that are generally yellow or orange in color . Golden algae are found in both freshwater and marine environments , where they form a major part of the plankton community . The brown algae are primarily marine , multicellular organisms that are known colloquially as seaweeds . Giant kelps are a type of brown algae . Some brown algae have evolved specialized tissues that resemble terrestrial plants , with root-like holdfasts , stem-like stipes , and leaf-like blades that are capable of photosynthesis . The stipes of giant kelps are enormous , extending in some cases for 60 meters . <hl> A variety of algal life cycles exists , but the most complex is alternation of generations , in which both haploid and diploid stages involve multicellularity . <hl> Compare this life cycle to that of humans , for instance . Haploid gametes produced by meiosis ( sperm and egg ) combine in fertilization to generate a diploid zygote that undergoes many rounds of mitosis to produce a multicellular embryo and then a fetus . However , the individual sperm and egg themselves never become multicellular beings . Terrestrial plants also have evolved alternation of generations . In the brown algae genus Laminaria , haploid spores develop into multicellular gametophytes , which produce haploid gametes that combine to produce diploid organisms that then become multicellular organisms with a different structure from the haploid form ( Figure 23.19 ) . Certain other organisms perform alternation of generations in which both the haploid and diploid forms look the same . Protist life cycles range from simple to extremely elaborate . Certain parasitic protists have complicated life cycles and must infect different host species at different developmental stages to complete their life cycle . Some protists are unicellular in the haploid form and multicellular in the diploid form , a strategy employed by animals . <hl> Other protists have multicellular stages in both haploid and diploid forms , a strategy called alternation of generations that is also used by plants . <hl>", "hl_sentences": "A variety of algal life cycles exists , but the most complex is alternation of generations , in which both haploid and diploid stages involve multicellularity . Other protists have multicellular stages in both haploid and diploid forms , a strategy called alternation of generations that is also used by plants .", "question": { "cloze_format": "Alternation of generations describes that ___ .", "normal_format": "Alternation of generations describes which of the following?", "question_choices": [ "The haploid form can be multicellular; the diploid form is unicellular.", "The haploid form is unicellular; the diploid form can be multicellular.", "Both the haploid and diploid forms can be multicellular.", "Neither the haploid nor the diploid forms can be multicellular." ], "question_id": "fs-idp52870384", "question_text": "Alternation of generations describes which of the following?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 2, "ans_text": "parabasalids" }, "bloom": "2", "hl_context": "<hl> A second Excavata subgroup , the parabasalids , also exhibits semi-functional mitochondria . <hl> <hl> In parabasalids , these structures function anaerobically and are called hydrogenosomes because they produce hydrogen gas as a byproduct . <hl> Parabasalids move with flagella and membrane rippling . Trichomonas vaginalis , a parabasalid that causes a sexually transmitted disease in humans , employs these mechanisms to transit through the male and female urogenital tracts . T . vaginalis causes trichamoniasis , which appears in an estimated 180 million cases worldwide each year . Whereas men rarely exhibit symptoms during an infection with this protist , infected women may become more susceptible to secondary infection with human immunodeficiency virus ( HIV ) and may be more likely to develop cervical cancer . Pregnant women infected with T . vaginalis are at an increased risk of serious complications , such as pre-term delivery .", "hl_sentences": "A second Excavata subgroup , the parabasalids , also exhibits semi-functional mitochondria . In parabasalids , these structures function anaerobically and are called hydrogenosomes because they produce hydrogen gas as a byproduct .", "question": { "cloze_format": "The protist group that exhibits mitochondrial remnants with reduced functionality is ___.", "normal_format": "Which protist group exhibits mitochondrial remnants with reduced functionality?", "question_choices": [ "slime molds", "diatoms", "parabasalids", "dinoflagellates" ], "question_id": "fs-idp147938368", "question_text": "Which protist group exhibits mitochondrial remnants with reduced functionality?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 2, "ans_text": "8" }, "bloom": null, "hl_context": "<hl> Paramecium has two nuclei , a macronucleus and a micronucleus , in each cell . <hl> <hl> The micronucleus is essential for sexual reproduction , whereas the macronucleus directs asexual binary fission and all other biological functions . <hl> <hl> The process of sexual reproduction in Paramecium underscores the importance of the micronucleus to these protists . <hl> <hl> Paramecium and most other ciliates reproduce sexually by conjugation . <hl> <hl> This process begins when two different mating types of Paramecium make physical contact and join with a cytoplasmic bridge ( Figure 23.16 ) . <hl> <hl> The diploid micronucleus in each cell then undergoes meiosis to produce four haploid micronuclei . <hl> <hl> Three of these degenerate in each cell , leaving one micronucleus that then undergoes mitosis , generating two haploid micronuclei . <hl> <hl> The cells each exchange one of these haploid nuclei and move away from each other . <hl> A similar process occurs in bacteria that have plasmids . Fusion of the haploid micronuclei generates a completely novel diploid pre-micronucleus in each conjugative cell . <hl> This pre-micronucleus undergoes three rounds of mitosis to produce eight copies , and the original macronucleus disintegrates . <hl> Four of the eight pre-micronuclei become full-fledged micronuclei , whereas the other four perform multiple rounds of DNA replication and go on to become new macronuclei . Two cell divisions then yield four new Paramecia from each original conjugative cell .", "hl_sentences": "Paramecium has two nuclei , a macronucleus and a micronucleus , in each cell . The micronucleus is essential for sexual reproduction , whereas the macronucleus directs asexual binary fission and all other biological functions . The process of sexual reproduction in Paramecium underscores the importance of the micronucleus to these protists . Paramecium and most other ciliates reproduce sexually by conjugation . This process begins when two different mating types of Paramecium make physical contact and join with a cytoplasmic bridge ( Figure 23.16 ) . The diploid micronucleus in each cell then undergoes meiosis to produce four haploid micronuclei . Three of these degenerate in each cell , leaving one micronucleus that then undergoes mitosis , generating two haploid micronuclei . The cells each exchange one of these haploid nuclei and move away from each other . This pre-micronucleus undergoes three rounds of mitosis to produce eight copies , and the original macronucleus disintegrates .", "question": { "cloze_format": "Conjugation between two Paramecia produces ________ total daughter cells.", "normal_format": "Conjugation between two Paramecia produces how many total daughter cells?", "question_choices": [ "2", "4", "8", "16" ], "question_id": "fs-idm7970480", "question_text": "Conjugation between two Paramecia produces ________ total daughter cells." }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 0, "ans_text": "locomotion" }, "bloom": "2", "hl_context": "<hl> The diatoms are unicellular photosynthetic protists that encase themselves in intricately patterned , glassy cell walls composed of silicon dioxide in a matrix of organic particles ( Figure 23.18 ) . <hl> These protists are a component of freshwater and marine plankton . Most species of diatoms reproduce asexually , although some instances of sexual reproduction and sporulation also exist . <hl> Some diatoms exhibit a slit in their silica shell , called a raphe . <hl> <hl> By expelling a stream of mucopolysaccharides from the raphe , the diatom can attach to surfaces or propel itself in one direction . <hl>", "hl_sentences": "The diatoms are unicellular photosynthetic protists that encase themselves in intricately patterned , glassy cell walls composed of silicon dioxide in a matrix of organic particles ( Figure 23.18 ) . Some diatoms exhibit a slit in their silica shell , called a raphe . By expelling a stream of mucopolysaccharides from the raphe , the diatom can attach to surfaces or propel itself in one direction .", "question": { "cloze_format": "The function of the raphe in diatoms is ___.", "normal_format": "What is the function of the raphe in diatoms?", "question_choices": [ "locomotion", "defense", "capturing food", "photosynthesis" ], "question_id": "fs-idp20931200", "question_text": "What is the function of the raphe in diatoms?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 3, "ans_text": "Caulerpa" }, "bloom": "3", "hl_context": "True multicellular organisms , such as the sea lettuce , Ulva , are represented among the chlorophytes . In addition , some chlorophytes exist as large , multinucleate , single cells . <hl> Species in the genus Caulerpa exhibit flattened fern-like foliage and can reach lengths of 3 meters ( Figure 23.25 ) . <hl> <hl> Caulerpa species undergo nuclear division , but their cells do not complete cytokinesis , remaining instead as massive and elaborate single cells . <hl>", "hl_sentences": "Species in the genus Caulerpa exhibit flattened fern-like foliage and can reach lengths of 3 meters ( Figure 23.25 ) . Caulerpa species undergo nuclear division , but their cells do not complete cytokinesis , remaining instead as massive and elaborate single cells .", "question": { "cloze_format": "___ is a genus of protists that appears to contradict the statement that unicellularity restricts cell size.", "normal_format": "What genus of protists appears to contradict the statement that unicellularity restricts cell size?", "question_choices": [ "Dictyostelium", "Ulva", "Plasmodium", "Caulerpa" ], "question_id": "fs-idp120219344", "question_text": "What genus of protists appears to contradict the statement that unicellularity restricts cell size?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 0, "ans_text": "photosynthesis" }, "bloom": null, "hl_context": "During periods of nutrient availability , diatom populations bloom to numbers greater than can be consumed by aquatic organisms . The excess diatoms die and sink to the sea floor where they are not easily reached by saprobes that feed on dead organisms . <hl> As a result , the carbon dioxide that the diatoms had consumed and incorporated into their cells during photosynthesis is not returned to the atmosphere . <hl> In general , this process by which carbon is transported deep into the ocean is described as the biological carbon pump , because carbon is “ pumped ” to the ocean depths where it is inaccessible to the atmosphere as carbon dioxide . The biological carbon pump is a crucial component of the carbon cycle that maintains lower atmospheric carbon dioxide levels .", "hl_sentences": "As a result , the carbon dioxide that the diatoms had consumed and incorporated into their cells during photosynthesis is not returned to the atmosphere .", "question": { "cloze_format": "An example of carbon fixation is _____________.", "normal_format": "What is an example of carbon fixation?", "question_choices": [ "photosynthesis", "decomposition", "phagocytosis", "parasitism" ], "question_id": "fs-idp175312", "question_text": "An example of carbon fixation is _____________." }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 1, "ans_text": "Trypanosoma brucei" }, "bloom": "2", "hl_context": "<hl> Trypanosoma brucei , the parasite that is responsible for African sleeping sickness , confounds the human immune system by changing its thick layer of surface glycoproteins with each infectious cycle ( Figure 23.32 ) . <hl> The glycoproteins are identified by the immune system as foreign antigens , and a specific antibody defense is mounted against the parasite . However , T . brucei has thousands of possible antigens , and with each subsequent generation , the protist switches to a glycoprotein coating with a different molecular structure . In this way , T . brucei is capable of replicating continuously without the immune system ever succeeding in clearing the parasite . Without treatment , T . brucei crosses the blood-brain barrier and infects the central nervous system , causing the patient to lapse into a coma and eventually die . During epidemic periods , mortality from the disease can be high . Greater surveillance and control measures lead to a reduction in reported cases ; some of the lowest numbers reported in 50 years ( fewer than 10,000 cases in all of sub-Saharan Africa ) have happened since 2009 . Link to Learning", "hl_sentences": "Trypanosoma brucei , the parasite that is responsible for African sleeping sickness , confounds the human immune system by changing its thick layer of surface glycoproteins with each infectious cycle ( Figure 23.32 ) .", "question": { "cloze_format": "The parasitic protist that evades the host immune system by altering its surface proteins with each generation is ___.", "normal_format": "Which parasitic protist evades the host immune system by altering its surface proteins with each generation?", "question_choices": [ "Paramecium caudatum", "Trypanosoma brucei", "Plasmodium falciparum", "Phytophthora infestans" ], "question_id": "fs-idm79453552", "question_text": "Which parasitic protist evades the host immune system by altering its surface proteins with each generation?" }, "references_are_paraphrase": null } ]
23
23.1 Eukaryotic Origins Learning Objectives By the end of this section, you will be able to: List the unifying characteristics of eukaryotes Describe what scientists know about the origins of eukaryotes based on the last common ancestor Explain endosymbiotic theory Living things fall into three large groups: Archaea, Bacteria, and Eukarya. The first two have prokaryotic cells, and the third contains all eukaryotes. A relatively sparse fossil record is available to help discern what the first members of each of these lineages looked like, so it is possible that all the events that led to the last common ancestor of extant eukaryotes will remain unknown. However, comparative biology of extant organisms and the limited fossil record provide some insight into the history of Eukarya. The earliest fossils found appear to be Bacteria, most likely cyanobacteria. They are about 3.5 billion years old and are recognizable because of their relatively complex structure and, for prokaryotes, relatively large cells. Most other prokaryotes have small cells, 1 or 2 µm in size, and would be difficult to pick out as fossils. Most living eukaryotes have cells measuring 10 µm or greater. Structures this size, which might be fossils, appear in the geological record about 2.1 billion years ago. Characteristics of Eukaryotes Data from these fossils have led comparative biologists to the conclusion that living eukaryotes are all descendants of a single common ancestor. Mapping the characteristics found in all major groups of eukaryotes reveals that the following characteristics must have been present in the last common ancestor, because these characteristics are present in at least some of the members of each major lineage. Cells with nuclei surrounded by a nuclear envelope with nuclear pores. This is the single characteristic that is both necessary and sufficient to define an organism as a eukaryote. All extant eukaryotes have cells with nuclei. Mitochondria. Some extant eukaryotes have very reduced remnants of mitochondria in their cells, whereas other members of their lineages have “typical” mitochondria. A cytoskeleton containing the structural and motility components called actin microfilaments and microtubules. All extant eukaryotes have these cytoskeletal elements. Flagella and cilia, organelles associated with cell motility. Some extant eukaryotes lack flagella and/or cilia, but they are descended from ancestors that possessed them. Chromosomes, each consisting of a linear DNA molecule coiled around basic (alkaline) proteins called histones. The few eukaryotes with chromosomes lacking histones clearly evolved from ancestors that had them. Mitosis, a process of nuclear division wherein replicated chromosomes are divided and separated using elements of the cytoskeleton. Mitosis is universally present in eukaryotes. Sex, a process of genetic recombination unique to eukaryotes in which diploid nuclei at one stage of the life cycle undergo meiosis to yield haploid nuclei and subsequent karyogamy, a stage where two haploid nuclei fuse together to create a diploid zygote nucleus. Members of all major lineages have cell walls, and it might be reasonable to conclude that the last common ancestor could make cell walls during some stage of its life cycle. However, not enough is known about eukaryotes’ cell walls and their development to know how much homology exists among them. If the last common ancestor could make cell walls, it is clear that this ability must have been lost in many groups. Endosymbiosis and the Evolution of Eukaryotes In order to understand eukaryotic organisms fully, it is necessary to understand that all extant eukaryotes are descendants of a chimeric organism that was a composite of a host cell and the cell(s) of an alpha-proteobacterium that “took up residence” inside it. This major theme in the origin of eukaryotes is known as endosymbiosis , one cell engulfing another such that the engulfed cell survives and both cells benefit. Over many generations, a symbiotic relationship can result in two organisms that depend on each other so completely that neither could survive on its own. Endosymbiotic events likely contributed to the origin of the last common ancestor of today’s eukaryotes and to later diversification in certain lineages of eukaryotes ( Figure 23.5 ). Before explaining this further, it is necessary to consider metabolism in prokaryotes. Prokaryotic Metabolism Many important metabolic processes arose in prokaryotes, and some of these, such as nitrogen fixation, are never found in eukaryotes. The process of aerobic respiration is found in all major lineages of eukaryotes, and it is localized in the mitochondria. Aerobic respiration is also found in many lineages of prokaryotes, but it is not present in all of them, and many forms of evidence suggest that such anaerobic prokaryotes never carried out aerobic respiration nor did their ancestors. While today’s atmosphere is about one-fifth molecular oxygen (O 2 ), geological evidence shows that it originally lacked O 2 . Without oxygen, aerobic respiration would not be expected, and living things would have relied on fermentation instead. At some point before, about 3.5 billion years ago, some prokaryotes began using energy from sunlight to power anabolic processes that reduce carbon dioxide to form organic compounds. That is, they evolved the ability to photosynthesize. Hydrogen, derived from various sources, was captured using light-powered reactions to reduce fixed carbon dioxide in the Calvin cycle. The group of Gram-negative bacteria that gave rise to cyanobacteria used water as the hydrogen source and released O 2 as a waste product. Eventually, the amount of photosynthetic oxygen built up in some environments to levels that posed a risk to living organisms, since it can damage many organic compounds. Various metabolic processes evolved that protected organisms from oxygen, one of which, aerobic respiration, also generated high levels of ATP. It became widely present among prokaryotes, including in a group we now call alpha-proteobacteria. Organisms that did not acquire aerobic respiration had to remain in oxygen-free environments. Originally, oxygen-rich environments were likely localized around places where cyanobacteria were active, but by about 2 billion years ago, geological evidence shows that oxygen was building up to higher concentrations in the atmosphere. Oxygen levels similar to today’s levels only arose within the last 700 million years. Recall that the first fossils that we believe to be eukaryotes date to about 2 billion years old, so they appeared as oxygen levels were increasing. Also, recall that all extant eukaryotes descended from an ancestor with mitochondria. These organelles were first observed by light microscopists in the late 1800s, where they appeared to be somewhat worm-shaped structures that seemed to be moving around in the cell. Some early observers suggested that they might be bacteria living inside host cells, but these hypotheses remained unknown or rejected in most scientific communities. Endosymbiotic Theory As cell biology developed in the twentieth century, it became clear that mitochondria were the organelles responsible for producing ATP using aerobic respiration. In the 1960s, American biologist Lynn Margulis developed endosymbiotic theory , which states that eukaryotes may have been a product of one cell engulfing another, one living within another, and evolving over time until the separate cells were no longer recognizable as such. In 1967, Margulis introduced new work on the theory and substantiated her findings through microbiological evidence. Although Margulis’ work initially was met with resistance, this once-revolutionary hypothesis is now widely (but not completely) accepted, with work progressing on uncovering the steps involved in this evolutionary process and the key players involved. Much still remains to be discovered about the origins of the cells that now make up the cells in all living eukaryotes. Broadly, it has become clear that many of our nuclear genes and the molecular machinery responsible for replication and expression appear closely related to those in Archaea. On the other hand, the metabolic organelles and genes responsible for many energy-harvesting processes had their origins in bacteria. Much remains to be clarified about how this relationship occurred; this continues to be an exciting field of discovery in biology. For instance, it is not known whether the endosymbiotic event that led to mitochondria occurred before or after the host cell had a nucleus. Such organisms would be among the extinct precursors of the last common ancestor of eukaryotes. Mitochondria One of the major features distinguishing prokaryotes from eukaryotes is the presence of mitochondria. Eukaryotic cells may contain anywhere from one to several thousand mitochondria, depending on the cell’s level of energy consumption. Each mitochondrion measures 1 to 10 or greater micrometers in length and exists in the cell as an organelle that can be ovoid to worm-shaped to intricately branched ( Figure 23.2 ). Mitochondria arise from the division of existing mitochondria; they may fuse together; and they may be moved around inside the cell by interactions with the cytoskeleton. However, mitochondria cannot survive outside the cell. As the atmosphere was oxygenated by photosynthesis, and as successful aerobic prokaryotes evolved, evidence suggests that an ancestral cell with some membrane compartmentalization engulfed a free-living aerobic prokaryote, specifically an alpha-proteobacterium, thereby giving the host cell the ability to use oxygen to release energy stored in nutrients. Alpha-proteobacteria are a large group of bacteria that includes species symbiotic with plants, disease organisms that can infect humans via ticks, and many free-living species that use light for energy. Several lines of evidence support that mitochondria are derived from this endosymbiotic event. Most mitochondria are shaped like alpha-proteobacteria and are surrounded by two membranes. The mitochondrial inner membrane is extensive and involves substantial infoldings called cristae that resemble the textured, outer surface of alpha-proteobacteria. The matrix and inner membrane are rich with the enzymes necessary for aerobic respiration. Mitochondria divide independently by a process that resembles binary fission in prokaryotes. Specifically, mitochondria are not formed from scratch (de novo) by the eukaryotic cell; they reproduce within it and are distributed with the cytoplasm when a cell divides or two cells fuse. Therefore, although these organelles are highly integrated into the eukaryotic cell, they still reproduce as if they are independent organisms within the cell. However, their reproduction is synchronized with the activity and division of the cell. Mitochondria have their own (usually) circular DNA chromosome that is stabilized by attachments to the inner membrane and carries genes similar to genes expressed by alpha-proteobacteria. Mitochondria also have special ribosomes and transfer RNAs that resemble these components in prokaryotes. These features all support that mitochondria were once free-living prokaryotes. Mitochondria that carry out aerobic respiration have their own genomes, with genes similar to those in alpha-proteobacteria. However, many of the genes for respiratory proteins are located in the nucleus. When these genes are compared to those of other organisms, they appear to be of alpha-proteobacterial origin. Additionally, in some eukaryotic groups, such genes are found in the mitochondria, whereas in other groups, they are found in the nucleus. This has been interpreted as evidence that genes have been transferred from the endosymbiont chromosome to the host genome. This loss of genes by the endosymbiont is probably one explanation why mitochondria cannot live without a host. Some living eukaryotes are anaerobic and cannot survive in the presence of too much oxygen. Some appear to lack organelles that could be recognized as mitochondria. In the 1970s to the early 1990s, many biologists suggested that some of these eukaryotes were descended from ancestors whose lineages had diverged from the lineage of mitochondrion-containing eukaryotes before endosymbiosis occurred. However, later findings suggest that reduced organelles are found in most, if not all, anaerobic eukaryotes, and that all eukaryotes appear to carry some genes in their nuclei that are of mitochondrial origin. In addition to the aerobic generation of ATP, mitochondria have several other metabolic functions. One of these functions is to generate clusters of iron and sulfur that are important cofactors of many enzymes. Such functions are often associated with the reduced mitochondrion-derived organelles of anaerobic eukaryotes. Therefore, most biologists accept that the last common ancestor of eukaryotes had mitochondria. Plastids Some groups of eukaryotes are photosynthetic. Their cells contain, in addition to the standard eukaryotic organelles, another kind of organelle called a plastid . When such cells are carrying out photosynthesis, their plastids are rich in the pigment chlorophyll a and a range of other pigments, called accessory pigments, which are involved in harvesting energy from light. Photosynthetic plastids are called chloroplasts ( Figure 23.3 ). Like mitochondria, plastids appear to have an endosymbiotic origin. This hypothesis was also championed by Lynn Margulis. Plastids are derived from cyanobacteria that lived inside the cells of an ancestral, aerobic, heterotrophic eukaryote. This is called primary endosymbiosis, and plastids of primary origin are surrounded by two membranes. The best evidence is that this has happened twice in the history of eukaryotes. In one case, the common ancestor of the major lineage/supergroup Archaeplastida took on a cyanobacterial endosymbiont; in the other, the ancestor of the small amoeboid rhizarian taxon, Paulinella , took on a different cyanobacterial endosymbiont. Almost all photosynthetic eukaryotes are descended from the first event, and only a couple of species are derived from the other. Cyanobacteria are a group of Gram-negative bacteria with all the conventional structures of the group. However, unlike most prokaryotes, they have extensive, internal membrane-bound sacs called thylakoids. Chlorophyll is a component of these membranes, as are many of the proteins of the light reactions of photosynthesis. Cyanobacteria also have the peptidoglycan wall and lipopolysaccharide layer associated with Gram-negative bacteria. Chloroplasts of primary origin have thylakoids, a circular DNA chromosome, and ribosomes similar to those of cyanobacteria. Each chloroplast is surrounded by two membranes. In the group of Archaeplastida called the glaucophytes and in Paulinella , a thin peptidoglycan layer is present between the outer and inner plastid membranes. All other plastids lack this relictual cyanobacterial wall. The outer membrane surrounding the plastid is thought to be derived from the vacuole in the host, and the inner membrane is thought to be derived from the plasma membrane of the symbiont. There is also, as with the case of mitochondria, strong evidence that many of the genes of the endosymbiont were transferred to the nucleus. Plastids, like mitochondria, cannot live independently outside the host. In addition, like mitochondria, plastids are derived from the division of other plastids and never built from scratch. Researchers have suggested that the endosymbiotic event that led to Archaeplastida occurred 1 to 1.5 billion years ago, at least 5 hundred million years after the fossil record suggests that eukaryotes were present. Not all plastids in eukaryotes are derived directly from primary endosymbiosis. Some of the major groups of algae became photosynthetic by secondary endosymbiosis, that is, by taking in either green algae or red algae (both from Archaeplastida) as endosymbionts ( Figure 23.4 ab ). Numerous microscopic and genetic studies have supported this conclusion. Secondary plastids are surrounded by three or more membranes, and some secondary plastids even have clear remnants of the nucleus of endosymbiotic alga. Others have not “kept” any remnants. There are cases where tertiary or higher-order endosymbiotic events are the best explanations for plastids in some eukaryotes. Visual Connection What evidence is there that mitochondria were incorporated into the ancestral eukaryotic cell before chloroplasts? Evolution Connection Secondary Endosymbiosis in Chlorarachniophytes Endosymbiosis involves one cell engulfing another to produce, over time, a coevolved relationship in which neither cell could survive alone. The chloroplasts of red and green algae, for instance, are derived from the engulfment of a photosynthetic cyanobacterium by an early prokaryote. This leads to the question of the possibility of a cell containing an endosymbiont to itself become engulfed, resulting in a secondary endosymbiosis. Molecular and morphological evidence suggest that the chlorarachniophyte protists are derived from a secondary endosymbiotic event. Chlorarachniophytes are rare algae indigenous to tropical seas and sand that can be classified into the rhizarian supergroup. Chlorarachniophytes extend thin cytoplasmic strands, interconnecting themselves with other chlorarachniophytes, in a cytoplasmic network. These protists are thought to have originated when a eukaryote engulfed a green alga, the latter of which had already established an endosymbiotic relationship with a photosynthetic cyanobacterium ( Figure 23.6 ). Several lines of evidence support that chlorarachniophytes evolved from secondary endosymbiosis. The chloroplasts contained within the green algal endosymbionts still are capable of photosynthesis, making chlorarachniophytes photosynthetic. The green algal endosymbiont also exhibits a stunted vestigial nucleus. In fact, it appears that chlorarachniophytes are the products of an evolutionarily recent secondary endosymbiotic event. The plastids of chlorarachniophytes are surrounded by four membranes: The first two correspond to the inner and outer membranes of the photosynthetic cyanobacterium, the third corresponds to the green alga, and the fourth corresponds to the vacuole that surrounded the green alga when it was engulfed by the chlorarachniophyte ancestor. In other lineages that involved secondary endosymbiosis, only three membranes can be identified around plastids. This is currently rectified as a sequential loss of a membrane during the course of evolution. The process of secondary endosymbiosis is not unique to chlorarachniophytes. In fact, secondary endosymbiosis of green algae also led to euglenid protists, whereas secondary endosymbiosis of red algae led to the evolution of dinoflagellates, apicomplexans, and stramenopiles. 23.2 Characteristics of Protists Learning Objectives By the end of this section, you will be able to: Describe the cell structure characteristics of protists Describe the metabolic diversity of protists Describe the life cycle diversity of protists There are over 100,000 described living species of protists, and it is unclear how many undescribed species may exist. Since many protists live as commensals or parasites in other organisms and these relationships are often species-specific, there is a huge potential for protist diversity that matches the diversity of hosts. As the catchall term for eukaryotic organisms that are not animal, plant, or fungi, it is not surprising that very few characteristics are common to all protists. Cell Structure The cells of protists are among the most elaborate of all cells. Most protists are microscopic and unicellular, but some true multicellular forms exist. A few protists live as colonies that behave in some ways as a group of free-living cells and in other ways as a multicellular organism. Still other protists are composed of enormous, multinucleate, single cells that look like amorphous blobs of slime, or in other cases, like ferns. In fact, many protist cells are multinucleated; in some species, the nuclei are different sizes and have distinct roles in protist cell function. Single protist cells range in size from less than a micrometer to three meters in length to hectares. Protist cells may be enveloped by animal-like cell membranes or plant-like cell walls. Others are encased in glassy silica-based shells or wound with pellicles of interlocking protein strips. The pellicle functions like a flexible coat of armor, preventing the protist from being torn or pierced without compromising its range of motion. Metabolism Protists exhibit many forms of nutrition and may be aerobic or anaerobic. Protists that store energy by photosynthesis belong to a group of photoautotrophs and are characterized by the presence of chloroplasts. Other protists are heterotrophic and consume organic materials (such as other organisms) to obtain nutrition. Amoebas and some other heterotrophic protist species ingest particles by a process called phagocytosis, in which the cell membrane engulfs a food particle and brings it inward, pinching off an intracellular membranous sac, or vesicle, called a food vacuole ( Figure 23.7 ). The vesicle containing the ingested particle, the phagosome, then fuses with a lysosome containing hydrolytic enzymes to produce a phagolysosome , and the food particle is broken down into small molecules that can diffuse into the cytoplasm and be used in cellular metabolism. Undigested remains ultimately are expelled from the cell via exocytosis. Subtypes of heterotrophs, called saprobes, absorb nutrients from dead organisms or their organic wastes. Some protists can function as mixotrophs , obtaining nutrition by photoautotrophic or heterotrophic routes, depending on whether sunlight or organic nutrients are available. Motility The majority of protists are motile, but different types of protists have evolved varied modes of movement ( Figure 23.8 ). Some protists have one or more flagella, which they rotate or whip. Others are covered in rows or tufts of tiny cilia that they coordinately beat to swim. Still others form cytoplasmic extensions called pseudopodia anywhere on the cell, anchor the pseudopodia to a substrate, and pull themselves forward. Some protists can move toward or away from a stimulus, a movement referred to as taxis. Movement toward light, termed phototaxis, is accomplished by coupling their locomotion strategy with a light-sensing organ. Life Cycles Protists reproduce by a variety of mechanisms. Most undergo some form of asexual reproduction, such as binary fission, to produce two daughter cells. In protists, binary fission can be divided into transverse or longitudinal, depending on the axis of orientation; sometimes Paramecium exhibits this method. Some protists such as the true slime molds exhibit multiple fission and simultaneously divide into many daughter cells. Others produce tiny buds that go on to divide and grow to the size of the parental protist. Sexual reproduction, involving meiosis and fertilization, is common among protists, and many protist species can switch from asexual to sexual reproduction when necessary. Sexual reproduction is often associated with periods when nutrients are depleted or environmental changes occur. Sexual reproduction may allow the protist to recombine genes and produce new variations of progeny that may be better suited to surviving in the new environment. However, sexual reproduction is often associated with resistant cysts that are a protective, resting stage. Depending on their habitat, the cysts may be particularly resistant to temperature extremes, desiccation, or low pH. This strategy also allows certain protists to “wait out” stressors until their environment becomes more favorable for survival or until they are carried (such as by wind, water, or transport on a larger organism) to a different environment, because cysts exhibit virtually no cellular metabolism. Protist life cycles range from simple to extremely elaborate. Certain parasitic protists have complicated life cycles and must infect different host species at different developmental stages to complete their life cycle. Some protists are unicellular in the haploid form and multicellular in the diploid form, a strategy employed by animals. Other protists have multicellular stages in both haploid and diploid forms, a strategy called alternation of generations that is also used by plants. Habitats Nearly all protists exist in some type of aquatic environment, including freshwater and marine environments, damp soil, and even snow. Several protist species are parasites that infect animals or plants. A few protist species live on dead organisms or their wastes, and contribute to their decay. 23.3 Groups of Protists Learning Objectives By the end of this section, you will be able to: Describe representative protist organisms from each of the six presently recognized supergroups of eukaryotes Identify the evolutionary relationships of plants, animals, and fungi within the six presently recognized supergroups of eukaryotes In the span of several decades, the Kingdom Protista has been disassembled because sequence analyses have revealed new genetic (and therefore evolutionary) relationships among these eukaryotes. Moreover, protists that exhibit similar morphological features may have evolved analogous structures because of similar selective pressures—rather than because of recent common ancestry. This phenomenon, called convergent evolution, is one reason why protist classification is so challenging. The emerging classification scheme groups the entire domain Eukaryota into six “supergroups” that contain all of the protists as well as animals, plants, and fungi that evolved from a common ancestor ( Figure 23.9 ). The supergroups are believed to be monophyletic, meaning that all organisms within each supergroup are believed to have evolved from a single common ancestor, and thus all members are most closely related to each other than to organisms outside that group. There is still evidence lacking for the monophyly of some groups. The classification of eukaryotes is still in flux, and the six supergroups may be modified or replaced by a more appropriate hierarchy as genetic, morphological, and ecological data accumulate. Keep in mind that the classification scheme presented here is just one of several hypotheses, and the true evolutionary relationships are still to be determined. When learning about protists, it is helpful to focus less on the nomenclature and more on the commonalities and differences that define the groups themselves. Excavata Many of the protist species classified into the supergroup Excavata are asymmetrical, single-celled organisms with a feeding groove “excavated” from one side. This supergroup includes heterotrophic predators, photosynthetic species, and parasites. Its subgroups are the diplomonads, parabasalids, and euglenozoans. Diplomonads Among the Excavata are the diplomonads, which include the intestinal parasite, Giardia lamblia ( Figure 23.10 ). Until recently, these protists were believed to lack mitochondria. Mitochondrial remnant organelles, called mitosomes , have since been identified in diplomonads, but these mitosomes are essentially nonfunctional. Diplomonads exist in anaerobic environments and use alternative pathways, such as glycolysis, to generate energy. Each diplomonad cell has two identical nuclei and uses several flagella for locomotion. Parabasalids A second Excavata subgroup, the parabasalids, also exhibits semi-functional mitochondria. In parabasalids, these structures function anaerobically and are called hydrogenosomes because they produce hydrogen gas as a byproduct. Parabasalids move with flagella and membrane rippling. Trichomonas vaginalis , a parabasalid that causes a sexually transmitted disease in humans, employs these mechanisms to transit through the male and female urogenital tracts. T . vaginalis causes trichamoniasis, which appears in an estimated 180 million cases worldwide each year. Whereas men rarely exhibit symptoms during an infection with this protist, infected women may become more susceptible to secondary infection with human immunodeficiency virus (HIV) and may be more likely to develop cervical cancer. Pregnant women infected with T . vaginalis are at an increased risk of serious complications, such as pre-term delivery. Euglenozoans Euglenozoans includes parasites, heterotrophs, autotrophs, and mixotrophs, ranging in size from 10 to 500 µm. Euglenoids move through their aquatic habitats using two long flagella that guide them toward light sources sensed by a primitive ocular organ called an eyespot. The familiar genus, Euglena , encompasses some mixotrophic species that display a photosynthetic capability only when light is present. In the dark, the chloroplasts of Euglena shrink up and temporarily cease functioning, and the cells instead take up organic nutrients from their environment. The human parasite, Trypanosoma brucei , belongs to a different subgroup of Euglenozoa, the kinetoplastids. The kinetoplastid subgroup is named after the kinetoplast , a DNA mass carried within the single, oversized mitochondrion possessed by each of these cells. This subgroup includes several parasites, collectively called trypanosomes, which cause devastating human diseases and infect an insect species during a portion of their life cycle. T . brucei develops in the gut of the tsetse fly after the fly bites an infected human or other mammalian host. The parasite then travels to the insect salivary glands to be transmitted to another human or other mammal when the infected tsetse fly consumes another blood meal. T . brucei is common in central Africa and is the causative agent of African sleeping sickness, a disease associated with severe chronic fatigue, coma, and can be fatal if left untreated. Link to Learning Watch this video to see T . brucei swimming. Click to view content Chromalveolata Current evidence suggests that species classified as chromalveolates are derived from a common ancestor that engulfed a photosynthetic red algal cell, which itself had already evolved chloroplasts from an endosymbiotic relationship with a photosynthetic prokaryote. Therefore, the ancestor of chromalveolates is believed to have resulted from a secondary endosymbiotic event. However, some chromalveolates appear to have lost red alga-derived plastid organelles or lack plastid genes altogether. Therefore, this supergroup should be considered a hypothesis-based working group that is subject to change. Chromalveolates include very important photosynthetic organisms, such as diatoms, brown algae, and significant disease agents in animals and plants. The chromalveolates can be subdivided into alveolates and stramenopiles. Alveolates: Dinoflagellates, Apicomplexians, and Ciliates A large body of data supports that the alveolates are derived from a shared common ancestor. The alveolates are named for the presence of an alveolus, or membrane-enclosed sac, beneath the cell membrane. The exact function of the alveolus is unknown, but it may be involved in osmoregulation. The alveolates are further categorized into some of the better-known protists: the dinoflagellates, the apicomplexans, and the ciliates. Dinoflagellates exhibit extensive morphological diversity and can be photosynthetic, heterotrophic, or mixotrophic. Many dinoflagellates are encased in interlocking plates of cellulose. Two perpendicular flagella fit into the grooves between the cellulose plates, with one flagellum extending longitudinally and a second encircling the dinoflagellate ( Figure 23.12 ). Together, the flagella contribute to the characteristic spinning motion of dinoflagellates. These protists exist in freshwater and marine habitats, and are a component of plankton , the typically microscopic organisms that drift through the water and serve as a crucial food source for larger aquatic organisms. Some dinoflagellates generate light, called bioluminescence , when they are jarred or stressed. Large numbers of marine dinoflagellates (billions or trillions of cells per wave) can emit light and cause an entire breaking wave to twinkle or take on a brilliant blue color ( Figure 23.13 ). For approximately 20 species of marine dinoflagellates, population explosions (also called blooms) during the summer months can tint the ocean with a muddy red color. This phenomenon is called a red tide, and it results from the abundant red pigments present in dinoflagellate plastids. In large quantities, these dinoflagellate species secrete an asphyxiating toxin that can kill fish, birds, and marine mammals. Red tides can be massively detrimental to commercial fisheries, and humans who consume these protists may become poisoned. The apicomplexan protists are so named because their microtubules, fibrin, and vacuoles are asymmetrically distributed at one end of the cell in a structure called an apical complex ( Figure 23.14 ). The apical complex is specialized for entry and infection of host cells. Indeed, all apicomplexans are parasitic. This group includes the genus Plasmodium , which causes malaria in humans. Apicomplexan life cycles are complex, involving multiple hosts and stages of sexual and asexual reproduction. The ciliates, which include Paramecium and Tetrahymena , are a group of protists 10 to 3,000 micrometers in length that are covered in rows, tufts, or spirals of tiny cilia. By beating their cilia synchronously or in waves, ciliates can coordinate directed movements and ingest food particles. Certain ciliates have fused cilia-based structures that function like paddles, funnels, or fins. Ciliates also are surrounded by a pellicle, providing protection without compromising agility. The genus Paramecium includes protists that have organized their cilia into a plate-like primitive mouth, called an oral groove, which is used to capture and digest bacteria ( Figure 23.15 ). Food captured in the oral groove enters a food vacuole, where it combines with digestive enzymes. Waste particles are expelled by an exocytic vesicle that fuses at a specific region on the cell membrane, called the anal pore. In addition to a vacuole-based digestive system, Paramecium also uses contractile vacuoles , which are osmoregulatory vesicles that fill with water as it enters the cell by osmosis and then contract to squeeze water from the cell. Link to Learning Watch the video of the contractile vacuole of Paramecium expelling water to keep the cell osmotically balanced. Click to view content Paramecium has two nuclei, a macronucleus and a micronucleus, in each cell. The micronucleus is essential for sexual reproduction, whereas the macronucleus directs asexual binary fission and all other biological functions. The process of sexual reproduction in Paramecium underscores the importance of the micronucleus to these protists. Paramecium and most other ciliates reproduce sexually by conjugation. This process begins when two different mating types of Paramecium make physical contact and join with a cytoplasmic bridge ( Figure 23.16 ). The diploid micronucleus in each cell then undergoes meiosis to produce four haploid micronuclei. Three of these degenerate in each cell, leaving one micronucleus that then undergoes mitosis, generating two haploid micronuclei. The cells each exchange one of these haploid nuclei and move away from each other. A similar process occurs in bacteria that have plasmids. Fusion of the haploid micronuclei generates a completely novel diploid pre-micronucleus in each conjugative cell. This pre-micronucleus undergoes three rounds of mitosis to produce eight copies, and the original macronucleus disintegrates. Four of the eight pre-micronuclei become full-fledged micronuclei, whereas the other four perform multiple rounds of DNA replication and go on to become new macronuclei. Two cell divisions then yield four new Paramecia from each original conjugative cell. Visual Connection Which of the following statements about Paramecium sexual reproduction is false? The macronuclei are derived from micronuclei. Both mitosis and meiosis occur during sexual reproduction. The conjugate pair swaps macronucleii. Each parent produces four daughter cells. Stramenopiles: Diatoms, Brown Algae, Golden Algae and Oomycetes The other subgroup of chromalveolates, the stramenopiles, includes photosynthetic marine algae and heterotrophic protists. The unifying feature of this group is the presence of a textured, or “hairy,” flagellum. Many stramenopiles also have an additional flagellum that lacks hair-like projections ( Figure 23.17 ). Members of this subgroup range in size from single-celled diatoms to the massive and multicellular kelp. The diatoms are unicellular photosynthetic protists that encase themselves in intricately patterned, glassy cell walls composed of silicon dioxide in a matrix of organic particles ( Figure 23.18 ). These protists are a component of freshwater and marine plankton. Most species of diatoms reproduce asexually, although some instances of sexual reproduction and sporulation also exist. Some diatoms exhibit a slit in their silica shell, called a raphe . By expelling a stream of mucopolysaccharides from the raphe, the diatom can attach to surfaces or propel itself in one direction. During periods of nutrient availability, diatom populations bloom to numbers greater than can be consumed by aquatic organisms. The excess diatoms die and sink to the sea floor where they are not easily reached by saprobes that feed on dead organisms. As a result, the carbon dioxide that the diatoms had consumed and incorporated into their cells during photosynthesis is not returned to the atmosphere. In general, this process by which carbon is transported deep into the ocean is described as the biological carbon pump , because carbon is “pumped” to the ocean depths where it is inaccessible to the atmosphere as carbon dioxide. The biological carbon pump is a crucial component of the carbon cycle that maintains lower atmospheric carbon dioxide levels. Like diatoms, golden algae are largely unicellular, although some species can form large colonies. Their characteristic gold color results from their extensive use of carotenoids, a group of photosynthetic pigments that are generally yellow or orange in color. Golden algae are found in both freshwater and marine environments, where they form a major part of the plankton community. The brown algae are primarily marine, multicellular organisms that are known colloquially as seaweeds. Giant kelps are a type of brown algae. Some brown algae have evolved specialized tissues that resemble terrestrial plants, with root-like holdfasts, stem-like stipes, and leaf-like blades that are capable of photosynthesis. The stipes of giant kelps are enormous, extending in some cases for 60 meters. A variety of algal life cycles exists, but the most complex is alternation of generations, in which both haploid and diploid stages involve multicellularity. Compare this life cycle to that of humans, for instance. Haploid gametes produced by meiosis (sperm and egg) combine in fertilization to generate a diploid zygote that undergoes many rounds of mitosis to produce a multicellular embryo and then a fetus. However, the individual sperm and egg themselves never become multicellular beings. Terrestrial plants also have evolved alternation of generations. In the brown algae genus Laminaria , haploid spores develop into multicellular gametophytes, which produce haploid gametes that combine to produce diploid organisms that then become multicellular organisms with a different structure from the haploid form ( Figure 23.19 ). Certain other organisms perform alternation of generations in which both the haploid and diploid forms look the same. Visual Connection Which of the following statements about the Laminaria life cycle is false? 1 n zoospores form in the sporangia. The sporophyte is the 2 n plant. The gametophyte is diploid. Both the gametophyte and sporophyte stages are multicellular. The water molds, oomycetes (“egg fungus”), were so-named based on their fungus-like morphology, but molecular data have shown that the water molds are not closely related to fungi. The oomycetes are characterized by a cellulose-based cell wall and an extensive network of filaments that allow for nutrient uptake. As diploid spores, many oomycetes have two oppositely directed flagella (one hairy and one smooth) for locomotion. The oomycetes are nonphotosynthetic and include many saprobes and parasites. The saprobes appear as white fluffy growths on dead organisms ( Figure 23.20 ). Most oomycetes are aquatic, but some parasitize terrestrial plants. One plant pathogen is Phytophthora infestans , the causative agent of late blight of potatoes, such as occurred in the nineteenth century Irish potato famine. Rhizaria The Rhizaria supergroup includes many of the amoebas, most of which have threadlike or needle-like pseudopodia ( Figure 23.21 ). Pseudopodia function to trap and engulf food particles and to direct movement in rhizarian protists. These pseudopods project outward from anywhere on the cell surface and can anchor to a substrate. The protist then transports its cytoplasm into the pseudopod, thereby moving the entire cell. This type of motion, called cytoplasmic streaming , is used by several diverse groups of protists as a means of locomotion or as a method to distribute nutrients and oxygen. Link to Learning Take a look at this video to see cytoplasmic streaming in a green alga. Click to view content Forams Foraminiferans, or forams, are unicellular heterotrophic protists, ranging from approximately 20 micrometers to several centimeters in length, and occasionally resembling tiny snails ( Figure 23.22 ). As a group, the forams exhibit porous shells, called tests that are built from various organic materials and typically hardened with calcium carbonate. The tests may house photosynthetic algae, which the forams can harvest for nutrition. Foram pseudopodia extend through the pores and allow the forams to move, feed, and gather additional building materials. Typically, forams are associated with sand or other particles in marine or freshwater habitats. Foraminiferans are also useful as indicators of pollution and changes in global weather patterns. Radiolarians A second subtype of Rhizaria, the radiolarians, exhibit intricate exteriors of glassy silica with radial or bilateral symmetry ( Figure 23.23 ). Needle-like pseudopods supported by microtubules radiate outward from the cell bodies of these protists and function to catch food particles. The shells of dead radiolarians sink to the ocean floor, where they may accumulate in 100 meter-thick depths. Preserved, sedimented radiolarians are very common in the fossil record. Archaeplastida Red algae and green algae are included in the supergroup Archaeplastida. It was from a common ancestor of these protists that the land plants evolved, since their closest relatives are found in this group. Molecular evidence supports that all Archaeplastida are descendents of an endosymbiotic relationship between a heterotrophic protist and a cyanobacterium. The red and green algae include unicellular, multicellular, and colonial forms. Red Algae Red algae, or rhodophytes, are primarily multicellular, lack flagella, and range in size from microscopic, unicellular protists to large, multicellular forms grouped into the informal seaweed category. The red algae life cycle is an alternation of generations. Some species of red algae contain phycoerythrins, photosynthetic accessory pigments that are red in color and outcompete the green tint of chlorophyll, making these species appear as varying shades of red. Other protists classified as red algae lack phycoerythrins and are parasites. Red algae are common in tropical waters where they have been detected at depths of 260 meters. Other red algae exist in terrestrial or freshwater environments. Green Algae: Chlorophytes and Charophytes The most abundant group of algae is the green algae. The green algae exhibit similar features to the land plants, particularly in terms of chloroplast structure. That this group of protists shared a relatively recent common ancestor with land plants is well supported. The green algae are subdivided into the chlorophytes and the charophytes. The charophytes are the closest living relatives to land plants and resemble them in morphology and reproductive strategies. Charophytes are common in wet habitats, and their presence often signals a healthy ecosystem. The chlorophytes exhibit great diversity of form and function. Chlorophytes primarily inhabit freshwater and damp soil, and are a common component of plankton. Chlamydomonas is a simple, unicellular chlorophyte with a pear-shaped morphology and two opposing, anterior flagella that guide this protist toward light sensed by its eyespot. More complex chlorophyte species exhibit haploid gametes and spores that resemble Chlamydomonas . The chlorophyte Volvox is one of only a few examples of a colonial organism, which behaves in some ways like a collection of individual cells, but in other ways like the specialized cells of a multicellular organism ( Figure 23.24 ). Volvox colonies contain 500 to 60,000 cells, each with two flagella, contained within a hollow, spherical matrix composed of a gelatinous glycoprotein secretion. Individual Volvox cells move in a coordinated fashion and are interconnected by cytoplasmic bridges. Only a few of the cells reproduce to create daughter colonies, an example of basic cell specialization in this organism. True multicellular organisms, such as the sea lettuce, Ulva , are represented among the chlorophytes. In addition, some chlorophytes exist as large, multinucleate, single cells. Species in the genus Caulerpa exhibit flattened fern-like foliage and can reach lengths of 3 meters ( Figure 23.25 ). Caulerpa species undergo nuclear division, but their cells do not complete cytokinesis, remaining instead as massive and elaborate single cells. Amoebozoa The amoebozoans characteristically exhibit pseudopodia that extend like tubes or flat lobes, rather than the hair-like pseudopodia of rhizarian amoeba ( Figure 23.26 ). The Amoebozoa include several groups of unicellular amoeba-like organisms that are free-living or parasites. Slime Molds A subset of the amoebozoans, the slime molds, has several morphological similarities to fungi that are thought to be the result of convergent evolution. For instance, during times of stress, some slime molds develop into spore-generating fruiting bodies, much like fungi. The slime molds are categorized on the basis of their life cycles into plasmodial or cellular types. Plasmodial slime molds are composed of large, multinucleate cells and move along surfaces like an amorphous blob of slime during their feeding stage ( Figure 23.27 ). Food particles are lifted and engulfed into the slime mold as it glides along. Upon maturation, the plasmodium takes on a net-like appearance with the ability to form fruiting bodies, or sporangia, during times of stress. Haploid spores are produced by meiosis within the sporangia, and spores can be disseminated through the air or water to potentially land in more favorable environments. If this occurs, the spores germinate to form ameboid or flagellate haploid cells that can combine with each other and produce a diploid zygotic slime mold to complete the life cycle. The cellular slime molds function as independent amoeboid cells when nutrients are abundant ( Figure 23.28 ). When food is depleted, cellular slime molds pile onto each other into a mass of cells that behaves as a single unit, called a slug. Some cells in the slug contribute to a 2–3-millimeter stalk, drying up and dying in the process. Cells atop the stalk form an asexual fruiting body that contains haploid spores. As with plasmodial slime molds, the spores are disseminated and can germinate if they land in a moist environment. One representative genus of the cellular slime molds is Dictyostelium , which commonly exists in the damp soil of forests. Link to Learning View this video to see the formation of a fruiting body by a cellular slime mold. Click to view content Opisthokonta The opisthokonts include the animal-like choanoflagellates, which are believed to resemble the common ancestor of sponges and, in fact, all animals. Choanoflagellates include unicellular and colonial forms, and number about 244 described species. These organisms exhibit a single, apical flagellum that is surrounded by a contractile collar composed of microvilli. The collar uses a similar mechanism to sponges to filter out bacteria for ingestion by the protist. The morphology of choanoflagellates was recognized early on as resembling the collar cells of sponges, and suggesting a possible relationship to animals. The Mesomycetozoa form a small group of parasites, primarily of fish, and at least one form that can parasitize humans. Their life cycles are poorly understood. These organisms are of special interest, because they appear to be so closely related to animals. In the past, they were grouped with fungi and other protists based on their morphology. 23.4 Ecology of Protists Learning Objectives By the end of this section, you will be able to: Describe the role that protists play in the ecosystem Describe important pathogenic species of protists Protists function in various ecological niches. Whereas some protist species are essential components of the food chain and generators of biomass, others function in the decomposition of organic materials. Still other protists are dangerous human pathogens or causative agents of devastating plant diseases. Primary Producers/Food Sources Protists are essential sources of nutrition for many other organisms. In some cases, as in plankton, protists are consumed directly. Alternatively, photosynthetic protists serve as producers of nutrition for other organisms. For instance, photosynthetic dinoflagellates called zooxanthellae use sunlight to fix inorganic carbon. In this symbiotic relationship, these protists provide nutrients for coral polyps ( Figure 23.29 ) that house them, giving corals a boost of energy to secrete a calcium carbonate skeleton. In turn, the corals provide the protist with a protected environment and the compounds needed for photosynthesis. This type of symbiotic relationship is important in nutrient-poor environments. Without dinoflagellate symbionts, corals lose algal pigments in a process called coral bleaching, and they eventually die. This explains why reef-building corals do not reside in waters deeper than 20 meters: insufficient light reaches those depths for dinoflagellates to photosynthesize. The protists themselves and their products of photosynthesis are essential—directly or indirectly—to the survival of organisms ranging from bacteria to mammals ( Figure 23.30 ). As primary producers, protists feed a large proportion of the world’s aquatic species. (On land, terrestrial plants serve as primary producers.) In fact, approximately one-quarter of the world’s photosynthesis is conducted by protists, particularly dinoflagellates, diatoms, and multicellular algae. Protists do not create food sources only for sea-dwelling organisms. For instance, certain anaerobic parabasalid species exist in the digestive tracts of termites and wood-eating cockroaches, where they contribute an essential step in the digestion of cellulose ingested by these insects as they bore through wood. Human Pathogens A pathogen is anything that causes disease. Parasites live in or on an organism and harm the organism. A significant number of protists are pathogenic parasites that must infect other organisms to survive and propagate. Protist parasites include the causative agents of malaria, African sleeping sickness, and waterborne gastroenteritis in humans. Other protist pathogens prey on plants, effecting massive destruction of food crops. Plasmodium Species Members of the genus Plasmodium must colonize both a mosquito and a vertebrate to complete their life cycle. In vertebrates, the parasite develops in liver cells and goes on to infect red blood cells, bursting from and destroying the blood cells with each asexual replication cycle ( Figure 23.31 ). Of the four Plasmodium species known to infect humans, P . falciparum accounts for 50 percent of all malaria cases and is the primary cause of disease-related fatalities in tropical regions of the world. In 2010, it was estimated that malaria caused between one-half and one million deaths, mostly in African children. During the course of malaria, P . falciparum can infect and destroy more than one-half of a human’s circulating blood cells, leading to severe anemia. In response to waste products released as the parasites burst from infected blood cells, the host immune system mounts a massive inflammatory response with episodes of delirium-inducing fever as parasites lyse red blood cells, spilling parasite waste into the bloodstream. P . falciparum is transmitted to humans by the African malaria mosquito, Anopheles gambiae . Techniques to kill, sterilize, or avoid exposure to this highly aggressive mosquito species are crucial to malaria control. Link to Learning This movie depicts the pathogenesis of Plasmodium falciparum , the causative agent of malaria. Trypanosomes Trypanosoma brucei , the parasite that is responsible for African sleeping sickness, confounds the human immune system by changing its thick layer of surface glycoproteins with each infectious cycle ( Figure 23.32 ). The glycoproteins are identified by the immune system as foreign antigens, and a specific antibody defense is mounted against the parasite. However, T . brucei has thousands of possible antigens, and with each subsequent generation, the protist switches to a glycoprotein coating with a different molecular structure. In this way, T . brucei is capable of replicating continuously without the immune system ever succeeding in clearing the parasite. Without treatment, T . brucei crosses the blood-brain barrier and infects the central nervous system, causing the patient to lapse into a coma and eventually die. During epidemic periods, mortality from the disease can be high. Greater surveillance and control measures lead to a reduction in reported cases; some of the lowest numbers reported in 50 years (fewer than 10,000 cases in all of sub-Saharan Africa) have happened since 2009. Link to Learning This movie discusses the pathogenesis of Trypanosoma brucei , the causative agent of African sleeping sickness. In Latin America, another species, T . cruzi , is responsible for Chagas disease. T . cruzi infections are mainly caused by a blood-sucking bug. The parasite inhabits heart and digestive system tissues in the chronic phase of infection, leading to malnutrition and heart failure due to abnormal heart rhythms. An estimated 10 million people are infected with Chagas disease, and it caused 10,000 deaths in 2008. Plant Parasites Protist parasites of terrestrial plants include agents that destroy food crops. The oomycete Plasmopara viticola parasitizes grape plants, causing a disease called downy mildew ( Figure 23.33 ). Grape plants infected with P . viticola appear stunted and have discolored, withered leaves. The spread of downy mildew nearly collapsed the French wine industry in the nineteenth century. Phytophthora infestans is an oomycete responsible for potato late blight, which causes potato stalks and stems to decay into black slime ( Figure 23.34 ). Widespread potato blight caused by P . infestans precipitated the well-known Irish potato famine in the nineteenth century that claimed the lives of approximately 1 million people and led to the emigration of at least 1 million more from Ireland. Late blight continues to plague potato crops in certain parts of the United States and Russia, wiping out as much as 70 percent of crops when no pesticides are applied. Agents of Decomposition The fungus-like protist saprobes are specialized to absorb nutrients from nonliving organic matter, such as dead organisms or their wastes. For instance, many types of oomycetes grow on dead animals or algae. Saprobic protists have the essential function of returning inorganic nutrients to the soil and water. This process allows for new plant growth, which in turn generates sustenance for other organisms along the food chain. Indeed, without saprobe species, such as protists, fungi, and bacteria, life would cease to exist as all organic carbon became “tied up” in dead organisms.
microbiology
Summary 19.1 Hypersensitivities An allergy is an adaptive immune response, sometimes life-threatening, to an allergen . Type I hypersensitivity requires sensitization of mast cells with IgE, involving an initial IgE antibody response and IgE attachment to mast cells. On second exposure to an allergen, cross-linking of IgE molecules on mast cells triggers degranulation and release of preformed and newly formed chemical mediators of inflammation. Type I hypersensitivity may be localized and relatively minor (hives and hay fever) or system-wide and dangerous (systemic anaphylaxis ). Type II hypersensitivities result from antibodies binding to antigens on cells and initiating cytotoxic responses. Examples include hemolytic transfusion reaction and hemolytic disease of the newborn . Type III hypersensitivities result from formation and accumulation of immune complexes in tissues, stimulating damaging inflammatory responses. Type IV hypersensitivities are not mediated by antibodies, but by helper T-cell activation of macrophages, eosinophils, and cytotoxic T cells. 19.2 Autoimmune Disorders Autoimmune diseases result from a breakdown in immunological tolerance. The actual induction event(s) for autoimmune states are largely unknown. Some autoimmune diseases attack specific organs, whereas others are more systemic. Organ-specific autoimmune diseases include celiac disease , Graves disease , Hashimoto thyroiditis , type I diabetes mellitus, and Addison disease . Systemic autoimmune diseases include multiple sclerosis , myasthenia gravis , psoriasis , rheumatoid arthritis , and systemic lupus erythematosus . Treatments for autoimmune diseases generally involve anti-inflammatory and immunosuppressive drugs. 19.3 Organ Transplantation and Rejection Grafts and transplants can be classified as autografts , isografts, allografts , or xenografts based on the genetic differences between the donor’s and recipient’s tissues. Genetic differences, especially among the MHC (HLA) genes, will dictate the likelihood that rejection of the transplanted tissue will occur. Transplant recipients usually require immunosuppressive therapy to avoid rejection, even with good genetic matching. This can create additional problems when immune responses are needed to fight off infectious agents and prevent cancer. Graft-versus-host disease can occur in bone marrow transplants, as the mature T cells in the transplant itself recognize the recipient’s tissues as foreign. Transplantation methods and technology have improved greatly in recent decades and may move into new areas with the use of stem cell technology to avoid the need for genetic matching of MHC molecules. 19.4 Immunodeficiency Primary immunodeficiencies are caused by genetic abnormalities; secondary immunodeficiencies are acquired through disease, diet, or environmental exposures Primary immunodeficiencies may result from flaws in phagocyte killing of innate immunity, or impairment of T cells and B cells. Primary immunodeficiencies include chronic granulomatous disease, X-linked agammaglobulinemia, selective IgA deficiency, and severe combined immunodeficiency disease. Secondary immunodeficiencies result from environmentally induced defects in B cells and/or T cells. Causes for secondary immunodeficiencies include malnutrition, viral infection, diabetes, prolonged infections, and chemical or radiation exposure. 19.5 Cancer Immunobiology and Immunotherapy Cancer results from a loss of control of the cell cycle, resulting in uncontrolled cell proliferation and a loss of the ability to differentiate. Adaptive and innate immune responses are engaged by tumor antigens, self-molecules only found on abnormal cells. These adaptive responses stimulate helper T cells to activate cytotoxic T cells and NK cells of innate immunity that will seek and destroy cancer cells. New anticancer therapies are in development that will exploit natural adaptive immunity anticancer responses. These include external stimulation of cytotoxic T cells and therapeutic vaccines that assist or enhance the immune response.
Chapter Outline 19.1 Hypersensitivities 19.2 Autoimmune Disorders 19.3 Organ Transplantation and Rejection 19.4 Immunodeficiency 19.5 Cancer Immunobiology and Immunotherapy Introduction An allergic reaction is an immune response to a type of antigen called an allergen . Allergens can be found in many different items, from peanuts and insect stings to latex and some drugs. Unlike other kinds of antigens, allergens are not necessarily associated with pathogenic microbes, and many allergens provoke no immune response at all in most people. Allergic responses vary in severity. Some are mild and localized, like hay fever or hives, but others can result in systemic, life-threatening reactions. Anaphylaxis, for example, is a rapidly developing allergic reaction that can cause a dangerous drop in blood pressure and severe swelling of the throat that may close off the airway. Allergies are just one example of how the immune system—the system normally responsible for preventing disease—can actually cause or mediate disease symptoms. In this chapter, we will further explore allergies and other disorders of the immune system, including hypersensitivity reactions, autoimmune diseases, transplant rejection, and diseases associated with immunodeficiency.
[ { "answer": { "ans_choice": 1, "ans_text": "B" }, "bloom": null, "hl_context": "<hl> Late-phase reactions in type I hypersensitivities may develop 4 – 12 hours after the early phase and are mediated by eosinophil s , neutrophil s , and lymphocytes that have been recruited by chemotactic factors released from mast cells . <hl> Activation of these recruited cells leads to the release of more chemical mediators that cause tissue damage and late-phase symptoms of swelling and redness of the skin , coughing , wheezing , and nasal discharge .", "hl_sentences": "Late-phase reactions in type I hypersensitivities may develop 4 – 12 hours after the early phase and are mediated by eosinophil s , neutrophil s , and lymphocytes that have been recruited by chemotactic factors released from mast cells .", "question": { "cloze_format": "___ is the type of cell largely responsible for type I hypersensitivity responses.", "normal_format": "Which of the following is the type of cell largely responsible for type I hypersensitivity responses?", "question_choices": [ "erythrocyte", "mast cell", "T lymphocyte", "antibody" ], "question_id": "fs-id1167661287580", "question_text": "Which of the following is the type of cell largely responsible for type I hypersensitivity responses?" }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 0, "ans_text": "A" }, "bloom": null, "hl_context": "<hl> Immune reactions categorized as type II hypersensitivities , or cytotoxic hypersensitivities , are mediated by IgG and IgM antibodies binding to cell-surface antigens or matrix-associated antigens on basement membranes . <hl> These antibodies can either activate complement , resulting in an inflammatory response and lysis of the targeted cells , or they can be involved in antibody-dependent cell-mediated cytotoxicity ( ADCC ) with cytotoxic T cell s .", "hl_sentences": "Immune reactions categorized as type II hypersensitivities , or cytotoxic hypersensitivities , are mediated by IgG and IgM antibodies binding to cell-surface antigens or matrix-associated antigens on basement membranes .", "question": { "cloze_format": "___ are the main mediators/initiators of type II hypersensitivity reactions.", "normal_format": "Which of the following are the main mediators/initiators of type II hypersensitivity reactions?", "question_choices": [ "antibodies", "mast cells", "erythrocytes", "histamines" ], "question_id": "fs-id1167661484321", "question_text": "Which of the following are the main mediators/initiators of type II hypersensitivity reactions?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 0, "ans_text": "A" }, "bloom": null, "hl_context": "<hl> Immune reactions categorized as type II hypersensitivities , or cytotoxic hypersensitivities , are mediated by IgG and IgM antibodies binding to cell-surface antigens or matrix-associated antigens on basement membranes . <hl> <hl> These antibodies can either activate complement , resulting in an inflammatory response and lysis of the targeted cells , or they can be involved in antibody-dependent cell-mediated cytotoxicity ( ADCC ) with cytotoxic T cell s . <hl>", "hl_sentences": "Immune reactions categorized as type II hypersensitivities , or cytotoxic hypersensitivities , are mediated by IgG and IgM antibodies binding to cell-surface antigens or matrix-associated antigens on basement membranes . These antibodies can either activate complement , resulting in an inflammatory response and lysis of the targeted cells , or they can be involved in antibody-dependent cell-mediated cytotoxicity ( ADCC ) with cytotoxic T cell s .", "question": { "cloze_format": "Inflammatory molecules are released by mast cells in type I hypersensitivities; type II hypersensitivities, however, are characterized by ___ .", "normal_format": "Inflammatory molecules are released by mast cells in type I hypersensitivities; type II hypersensitivities, however, are characterized by which of the following?", "question_choices": [ "cell lysis (cytotoxicity)", "strong antibody reactions against antigens", "leukotriene release upon stimulation", "localized tissue reactions, such as hives" ], "question_id": "fs-id1167663994798", "question_text": "Inflammatory molecules are released by mast cells in type I hypersensitivities; type II hypersensitivities, however, are characterized by which of the following?" }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 2, "ans_text": "C" }, "bloom": null, "hl_context": "<hl> A unique characteristic of type III hypersensitivity is antibody excess ( primarily IgG ) , coupled with a relatively low concentration of antigen , resulting in the formation of small immune complexes that deposit on the surface of the epithelial cells lining the inner lumen of small blood vessels or on the surfaces of tissues ( Figure 19.7 ) . <hl> This immune complex accumulation leads to a cascade of inflammatory events that include the following : <hl> Type III hypersensitivity reactions involve the interactions of IgG , IgM , and , occasionally , IgA 1 antibodies with antigen to form immune complexes . <hl> Accumulation of immune complexes in tissue leads to tissue damage mediated by other immune system effectors . 1 D . S . Strayer et al ( eds ) . Rubin ’ s Pathology : Clinicopathologic Foundations of Medicine . 7th ed . 2Philadelphia , PA : Lippincott , Williams & Wilkins , 2014 .", "hl_sentences": "A unique characteristic of type III hypersensitivity is antibody excess ( primarily IgG ) , coupled with a relatively low concentration of antigen , resulting in the formation of small immune complexes that deposit on the surface of the epithelial cells lining the inner lumen of small blood vessels or on the surfaces of tissues ( Figure 19.7 ) . Type III hypersensitivity reactions involve the interactions of IgG , IgM , and , occasionally , IgA 1 antibodies with antigen to form immune complexes .", "question": { "cloze_format": "An immune complex is an aggregate of ___ .", "normal_format": "An immune complex is an aggregate of which of the following?", "question_choices": [ "antibody molecules", "antigen molecules", "antibody and antigen molecules", "histamine molecules" ], "question_id": "fs-id1167663966837", "question_text": "An immune complex is an aggregate of which of the following?" }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 0, "ans_text": "A" }, "bloom": null, "hl_context": "<hl> Treatments of type III hypersensitivities include preventing further exposure to the antigen and the use of anti-inflammatory drugs . <hl> Some conditions can be resolved when exposure to the antigen is prevented . Anti-inflammatory corticosteroid inhalers can also be used to diminish inflammation to allow lung lesions to heal . <hl> Systemic corticosteroid treatment , oral or intravenous , is also common for type III hypersensitivities affecting body systems . <hl> Treatment of hypersensitivity pneumonitis includes avoiding the allergen , along with the possible addition of prescription steroids such as prednisone to reduce inflammation .", "hl_sentences": "Treatments of type III hypersensitivities include preventing further exposure to the antigen and the use of anti-inflammatory drugs . Systemic corticosteroid treatment , oral or intravenous , is also common for type III hypersensitivities affecting body systems .", "question": { "cloze_format": "___ are a common treatment for type III hypersensitivity reactions.", "normal_format": "Which of the following is a common treatment for type III hypersensitivity reactions?", "question_choices": [ "anti-inflammatory steroid treatments", "antihistamine treatments", "hyposensitization injections of allergens", "RhoGAM injections" ], "question_id": "fs-id1167663972786", "question_text": "Which of the following is a common treatment for type III hypersensitivity reactions?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 1, "ans_text": "B" }, "bloom": null, "hl_context": "<hl> A unique characteristic of type III hypersensitivity is antibody excess ( primarily IgG ) , coupled with a relatively low concentration of antigen , resulting in the formation of small immune complexes that deposit on the surface of the epithelial cells lining the inner lumen of small blood vessels or on the surfaces of tissues ( Figure 19.7 ) . <hl> This immune complex accumulation leads to a cascade of inflammatory events that include the following :", "hl_sentences": "A unique characteristic of type III hypersensitivity is antibody excess ( primarily IgG ) , coupled with a relatively low concentration of antigen , resulting in the formation of small immune complexes that deposit on the surface of the epithelial cells lining the inner lumen of small blood vessels or on the surfaces of tissues ( Figure 19.7 ) .", "question": { "cloze_format": "The ___ induces a type III hypersensitivity.", "normal_format": "Which of the following induces a type III hypersensitivity?", "question_choices": [ "release of inflammatory molecules from mast cells", "accumulation of immune complexes in tissues and small blood vessels", "destruction of cells bound by antigens", "destruction of cells bound by antibodies" ], "question_id": "fs-id1167661509076", "question_text": "Which of the following induces a type III hypersensitivity?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 3, "ans_text": "D" }, "bloom": null, "hl_context": "<hl> In the first type IV subcategory , CD4 T H 1 - mediated reactions are described as delayed-type hypersensitivities ( DTH ) . <hl> The sensitization step involves the introduction of antigen into the skin and phagocytosis by local antigen presenting cells ( APCs ) . The APCs activate helper T cells , stimulating clonal proliferation and differentiation into memory T H 1 cells . Upon subsequent exposure to the antigen , these sensitized memory T H 1 cells release cytokines that activate macrophages , and activated macrophages are responsible for much of the tissue damage . <hl> Examples of this T H 1 - mediated hypersensitivity are observed in tuberculin the Mantoux skin test and contact dermatitis , such as occurs in latex allergy reactions . <hl>", "hl_sentences": "In the first type IV subcategory , CD4 T H 1 - mediated reactions are described as delayed-type hypersensitivities ( DTH ) . Examples of this T H 1 - mediated hypersensitivity are observed in tuberculin the Mantoux skin test and contact dermatitis , such as occurs in latex allergy reactions .", "question": { "cloze_format": "___ is not an example of a type IV hypersensitivity.", "normal_format": "Which one of the following is not an example of a type IV hypersensitivity?", "question_choices": [ "latex allergy", "Contact dermatitis (e.g., contact with poison ivy)", "a positive tuberculin skin test", "hemolytic disease of the newborn" ], "question_id": "fs-id1167663992333", "question_text": "Which one of the following is not an example of a type IV hypersensitivity?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 2, "ans_text": "C" }, "bloom": null, "hl_context": "<hl> Some autoimmune diseases are considered organ specific , meaning that the immune system targets specific organs or tissues . <hl> <hl> Examples of organ-specific autoimmune diseases include celiac disease , Graves disease , Hashimoto thyroiditis , type I diabetes mellitus , and Addison disease . <hl>", "hl_sentences": "Some autoimmune diseases are considered organ specific , meaning that the immune system targets specific organs or tissues . Examples of organ-specific autoimmune diseases include celiac disease , Graves disease , Hashimoto thyroiditis , type I diabetes mellitus , and Addison disease .", "question": { "cloze_format": "___ is an example of an organ-specific autoimmune disease.", "normal_format": "Which of the following is an example of an organ-specific autoimmune disease?", "question_choices": [ "rheumatoid arthritis", "psoriasis", "Addison disease", "myasthenia gravis" ], "question_id": "fs-id1167661308687", "question_text": "Which of the following is an example of an organ-specific autoimmune disease?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 3, "ans_text": "D" }, "bloom": null, "hl_context": "<hl> Whereas organ-specific autoimmune diseases target specific organs or tissues , systemic autoimmune disease s are more generalized , targeting multiple organs or tissues throughout the body . <hl> <hl> Examples of systemic autoimmune diseases include multiple sclerosis , myasthenia gravis , psoriasis , rheumatoid arthritis , and systemic lupus erythematosus . <hl>", "hl_sentences": "Whereas organ-specific autoimmune diseases target specific organs or tissues , systemic autoimmune disease s are more generalized , targeting multiple organs or tissues throughout the body . Examples of systemic autoimmune diseases include multiple sclerosis , myasthenia gravis , psoriasis , rheumatoid arthritis , and systemic lupus erythematosus .", "question": { "cloze_format": "___ is an example of a systemic autoimmune disease.", "normal_format": "Which of the following is an example of a systemic autoimmune disease?", "question_choices": [ "Hashimoto thyroiditis", "type I diabetes mellitus", "Graves disease", "myasthenia gravis" ], "question_id": "fs-id1167663648910", "question_text": "Which of the following is an example of a systemic autoimmune disease?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 0, "ans_text": "A" }, "bloom": null, "hl_context": "<hl> Deficiencies in B cells due to defective differentiation lead to a lack of specific antibody production known as X-linked agammaglobulinemia . <hl> In 1952 , Ogden C . Bruton ( 1908 – 2003 ) described the first immunodeficiency in a boy whose immune system failed to produce antibodies . This defect is inherited on the X chromosome and is characterized by the absence of immunoglobulin in the serum ; it is called Bruton X-linked agammaglobulinemia ( XLA ) . The defective gene , BTK , in XLA is now known to encode a tyrosine kinase called Bruton tyrosine kinase ( Btk ) . In patients whose B cells are unable to produce sufficient amounts of Btk , the B-cell maturation and differentiation halts at the pre-B-cell stage of growth . B-cell maturation and differentiation beyond the pre-B-cell stage of growth is required for immunoglobulin production . Patients who lack antibody production suffer from recurrent infections almost exclusively due to extracellular pathogens that cause pyogenic infections : Haemophilus influenzae , Streptococcus pneumoniae , S . pyogenes , and S . aureus . Because cell-mediated immunity is not impaired , these patients are not particularly vulnerable to infections caused by viruses or intracellular pathogens .", "hl_sentences": "Deficiencies in B cells due to defective differentiation lead to a lack of specific antibody production known as X-linked agammaglobulinemia .", "question": { "cloze_format": "(The) ___ is a genetic disease that results in lack of production of antibodies.", "normal_format": "Which of the following is a genetic disease that results in lack of production of antibodies?", "question_choices": [ "agammaglobulinemia", "myasthenia gravis", "HIV/AIDS", "chronic granulomatous disease" ], "question_id": "fs-id1167662404622", "question_text": "Which of the following is a genetic disease that results in lack of production of antibodies?" }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 1, "ans_text": "B" }, "bloom": null, "hl_context": "<hl> Primary immunodeficiencies , which number more than 250 , are caused by inherited defects of either nonspecific innate or specific adaptive immune defenses . <hl> <hl> In general , patients born with primary immunodeficiency ( PI ) commonly have an increased susceptibility to infection . <hl> This susceptibility can become apparent shortly after birth or in early childhood for some individuals , whereas other patients develop symptoms later in life . Some primary immunodeficiencies are due to a defect of a single cellular or humoral component of the immune system ; others may result from defects of more than one component . <hl> Examples of primary immunodeficiencies include chronic granulomatous disease , X-linked agammaglobulinemia , selective IgA deficiency , and severe combined immunodeficiency disease . <hl>", "hl_sentences": "Primary immunodeficiencies , which number more than 250 , are caused by inherited defects of either nonspecific innate or specific adaptive immune defenses . In general , patients born with primary immunodeficiency ( PI ) commonly have an increased susceptibility to infection . Examples of primary immunodeficiencies include chronic granulomatous disease , X-linked agammaglobulinemia , selective IgA deficiency , and severe combined immunodeficiency disease .", "question": { "cloze_format": "___ is a genetic disease that results in almost no adaptive immunity due to lack of B and/ or T cells.", "normal_format": "Which of the following is a genetic disease that results in almost no adaptive immunity due to lack of B and/ or T cells?", "question_choices": [ "agammaglobulinemia", "severe combined immunodeficiency", "HIV/AIDS", "chronic granulomatous disease" ], "question_id": "fs-id1167660170633", "question_text": "Which of the following is a genetic disease that results in almost no adaptive immunity due to lack of B and/ or T cells?" }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 2, "ans_text": "C" }, "bloom": null, "hl_context": "Primary immunodeficiencies , which number more than 250 , are caused by inherited defects of either nonspecific innate or specific adaptive immune defenses . In general , patients born with primary immunodeficiency ( PI ) commonly have an increased susceptibility to infection . This susceptibility can become apparent shortly after birth or in early childhood for some individuals , whereas other patients develop symptoms later in life . Some primary immunodeficiencies are due to a defect of a single cellular or humoral component of the immune system ; others may result from defects of more than one component . <hl> Examples of primary immunodeficiencies include chronic granulomatous disease , X-linked agammaglobulinemia , selective IgA deficiency , and severe combined immunodeficiency disease . <hl>", "hl_sentences": "Examples of primary immunodeficiencies include chronic granulomatous disease , X-linked agammaglobulinemia , selective IgA deficiency , and severe combined immunodeficiency disease .", "question": { "cloze_format": "All but ___ are examples of secondary immunodeficiencies.", "normal_format": "All but which one of the following are examples of secondary immunodeficiencies?", "question_choices": [ "HIV/AIDS", "malnutrition", "chronic granulomatous disease", "immunosuppression due to measles infection" ], "question_id": "fs-id1167660659992", "question_text": "All but which one of the following are examples of secondary immunodeficiencies?" }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 2, "ans_text": "C" }, "bloom": null, "hl_context": "<hl> Cancer involves a loss of the ability of cells to control their cell cycle , the stages each eukaryotic cell goes through as it grows and then divides . <hl> When this control is lost , the affected cells rapidly divide and often lose the ability to differentiate into the cell type appropriate for their location in the body . In addition , they lose contact inhibition and can start to grow on top of each other . This can result in formation of a tumor . It is important to make a distinction here : The term “ cancer ” is used to describe the diseases resulting from loss of cell-cycle regulation and subsequent cell proliferation . But the term “ tumor ” is more general . A “ tumor ” is an abnormal mass of cells , and a tumor can be benign ( not cancerous ) or malignant ( cancerous ) .", "hl_sentences": "Cancer involves a loss of the ability of cells to control their cell cycle , the stages each eukaryotic cell goes through as it grows and then divides .", "question": { "cloze_format": "Cancer results when a mutation leads to ___.", "normal_format": "Cancer results when a mutation leads to which of the following?", "question_choices": [ "cell death", "apoptosis", "loss of cell-cycle control", "shutdown of the cell cycle" ], "question_id": "fs-id1167658344750", "question_text": "Cancer results when a mutation leads to which of the following?" }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 0, "ans_text": "A" }, "bloom": null, "hl_context": "Cell-mediated immune responses can be directed against cancer cells , many of which do not have the normal complement of self-proteins , making them a target for elimination . <hl> Abnormal cancer cells may also present tumor antigen s . These tumor antigens are not a part of the screening process used to eliminate lymphocytes during development ; thus , even though they are self-antigens , they can stimulate and drive adaptive immune responses against abnormal cells . <hl>", "hl_sentences": "Abnormal cancer cells may also present tumor antigen s . These tumor antigens are not a part of the screening process used to eliminate lymphocytes during development ; thus , even though they are self-antigens , they can stimulate and drive adaptive immune responses against abnormal cells .", "question": { "cloze_format": "Tumor antigens are ________ that are inappropriately expressed and found on abnormal cells.", "normal_format": "What are inappropriately expressed and found on abnormal cells that are tumor antigens?", "question_choices": [ "self antigens", "foreign antigens", "antibodies", "T-cell receptors" ], "question_id": "fs-id1167658344129", "question_text": "Tumor antigens are ________ that are inappropriately expressed and found on abnormal cells." }, "references_are_paraphrase": null } ]
19
19.1 Hypersensitivities Learning Objectives Identify and compare the distinguishing characteristics, mechanisms, and major examples of type I, II, III, and IV hypersensitivities Clinical Focus Part 1 Kerry, a 40-year-old airline pilot, has made an appointment with her primary care physician to discuss a rash that develops whenever she spends time in the sun. As she explains to her physician, it does not seem like sunburn. She is careful not to spend too much time in the sun and she uses sunscreen. Despite these precautions, the rash still appears, manifesting as red, raised patches that get slightly scaly. The rash persists for 7 to 10 days each time, and it seems to largely go away on its own. Lately, the rashes have also begun to appear on her cheeks and above her eyes on either side of her forehead. Is Kerry right to be concerned, or should she simply be more careful about sun exposure? Are there conditions that might be brought on by sun exposure that Kerry’s physician should be considering? Jump to the next Clinical Focus box. In Adaptive Specific Host Defenses , we discussed the mechanisms by which adaptive immune defenses, both humoral and cellular, protect us from infectious diseases. However, these same protective immune defenses can also be responsible for undesirable reactions called hypersensitivity reactions. Hypersensitivity reactions are classified by their immune mechanism. Type I hypersensitivity reactions involve immunoglobulin E (IgE) antibody against soluble antigen, triggering mast cell degranulation. Type II hypersensitivity reactions involve IgG and IgM antibodies directed against cellular antigens, leading to cell damage mediated by other immune system effectors. Type III hypersensitivity reactions involve the interactions of IgG, IgM, and, occasionally, IgA 1 antibodies with antigen to form immune complexes. Accumulation of immune complexes in tissue leads to tissue damage mediated by other immune system effectors. 1 D.S. Strayer et al (eds). Rubin’s Pathology: Clinicopathologic Foundations of Medicine . 7th ed. 2Philadelphia, PA: Lippincott, Williams & Wilkins, 2014. Type IV hypersensitivity reactions are T-cell–mediated reactions that can involve tissue damage mediated by activated macrophages and cytotoxic T cells. Type I Hypersensitivities When a presensitized individual is exposed to an allergen , it can lead to a rapid immune response that occurs almost immediately. Such a response is called an allergy and is classified as a type I hypersensitivity . Allergens may be seemingly harmless substances such as animal dander, molds, or pollen. Allergens may also be substances considered innately more hazardous, such as insect venom or therapeutic drugs. Food intolerances can also yield allergic reactions as individuals become sensitized to foods such as peanuts or shellfish ( Figure 19.2 ). Regardless of the allergen, the first exposure activates a primary IgE antibody response that sensitizes an individual to type I hypersensitivity reaction upon subsequent exposure. For susceptible individuals, a first exposure to an allergen activates a strong T H 2 cell response ( Figure 19.3 ). Cytokines interleukin (IL)-4 and IL-13 from the T H 2 cells activate B cells specific to the same allergen, resulting in clonal proliferation, differentiation into plasma cells, and antibody-class switch from production of IgM to production of IgE . The fragment crystallizable (Fc) regions of the IgE antibodies bind to specific receptors on the surface of mast cells throughout the body. It is estimated that each mast cell can bind up to 500,000 IgE molecules, with each IgE molecule having two allergen-specific fragment antigen-binding (Fab) sites available for binding allergen on subsequent exposures. By the time this occurs, the allergen is often no longer present and there is no allergic reaction, but the mast cells are primed for a subsequent exposure and the individual is sensitized to the allergen. On subsequent exposure, allergens bind to multiple IgE molecules on mast cells, cross-linking the IgE molecules. Within minutes, this cross-linking of IgE activates the mast cells and triggers degranulation , a reaction in which the contents of the granules in the mast cell are released into the extracellular environment. Preformed components that are released from granules include histamine , serotonin , and bradykinin ( Table 19.1 ). The activated mast cells also release newly formed lipid mediators ( leukotrienes and prostaglandins from membrane arachadonic acid metabolism) and cytokines such as tumor necrosis factor ( Table 19.2 ). The chemical mediators released by mast cells collectively cause the inflammation and signs and symptoms associated with type I hypersensitivity reactions. Histamine stimulates mucus secretion in nasal passages and tear formation from lacrimal glands, promoting the runny nose and watery eyes of allergies. Interaction of histamine with nerve endings causes itching and sneezing. The vasodilation caused by several of the mediators can result in hives, headaches, angioedema (swelling that often affects the lips, throat, and tongue), and hypotension (low blood pressure). Bronchiole constriction caused by some of the chemical mediators leads to wheezing, dyspnea (difficulty breathing), coughing, and, in more severe cases, cyanosis (bluish color to the skin or mucous membranes). Vomiting can result from stimulation of the vomiting center in the cerebellum by histamine and serotonin. Histamine can also cause relaxation of intestinal smooth muscles and diarrhea. Selected Preformed Components of Mast Cell Granules Granule Component Activity Heparin Stimulates the generation of bradykinin, which causes increased vascular permeability, vasodilation, bronchiole constriction, and increased mucus secretion Histamine Causes smooth-muscle contraction, increases vascular permeability, increases mucus and tear formation Serotonin Increases vascular permeability, causes vasodilation and smooth-muscle contraction Table 19.1 Selected Newly Formed Chemical Mediators of Inflammation and Allergic Response Chemical Mediator Activity Leukotriene Causes smooth-muscle contraction and mucus secretion, increases vascular permeability Prostaglandin Causes smooth-muscle contraction and vasodilation TNF-α (cytokine) Causes inflammation and stimulates cytokine production by other cell types Table 19.2 Type I hypersensitivity reactions can be either localized or systemic. Localized type I hypersensitivity reactions include hay fever rhinitis , hives, and asthma ( Table 19.3 ). Systemic type I hypersensitivity reactions are referred to as anaphylaxis or anaphylactic shock . Although anaphylaxis shares many symptoms common with the localized type I hypersensitivity reactions, the swelling of the tongue and trachea, blockage of airways, dangerous drop in blood pressure, and development of shock can make anaphylaxis especially severe and life-threatening. In fact, death can occur within minutes of onset of signs and symptoms. Late-phase reactions in type I hypersensitivities may develop 4–12 hours after the early phase and are mediated by eosinophil s, neutrophil s, and lymphocytes that have been recruited by chemotactic factors released from mast cells . Activation of these recruited cells leads to the release of more chemical mediators that cause tissue damage and late-phase symptoms of swelling and redness of the skin, coughing, wheezing, and nasal discharge. Individuals who possess genes for maladaptive traits, such as intense type I hypersensitivity reactions to otherwise harmless components of the environment, would be expected to suffer reduced reproductive success. With this kind of evolutionary selective pressure, such traits would not be expected to persist in a population. This suggests that type I hypersensitivities may have an adaptive function. There is evidence that the IgE produced during type I hypersensitivity reactions is actually meant to counter helminth infections 2 . Helminths are one of few organisms that possess proteins that are targeted by IgE. In addition, there is evidence that helminth infections at a young age reduce the likelihood of type I hypersensitivities to innocuous substances later in life. Thus it may be that allergies are an unfortunate consequence of strong selection in the mammalian lineage or earlier for a defense against parasitic worms . 2 C.M. Fitzsimmons et al. “Helminth Allergens, Parasite-Specific IgE, and Its Protective Role in Human Immunity.” Frontier in Immunology 5 (2015):47. Type I Hypersensitivities Common Name Cause Signs and Symptoms Allergy-induced asthma Inhalation of allergens Constriction of bronchi, labored breathing, coughing, chills, body aches Anaphylaxis Systemic reaction to allergens Hives, itching, swelling of tongue and throat, nausea, vomiting, low blood pressure, shock Hay fever Inhalation of mold or pollen Runny nose, watery eyes, sneezing Hives (urticaria) Food or drug allergens, insect stings Raised, bumpy skin rash with itching; bumps may converge into large raised areas Table 19.3 Check Your Understanding What are the cells that cause a type I hypersensitivity reaction? Describe the differences between immediate and late-phase type I hypersensitivity reactions. List the signs and symptoms of anaphylaxis. Micro Connections The Hygiene Hypothesis In most modern societies, good hygiene is associated with regular bathing, and good health with cleanliness. But some recent studies suggest that the association between health and clean living may be a faulty one. Some go so far as to suggest that children should be encouraged to play in the dirt—or even eat dirt 3 —for the benefit of their health. This recommendation is based on the so-called hygiene hypothesis , which proposes that childhood exposure to antigens from a diverse range of microbes leads to a better-functioning immune system later in life. 3 S.T. Weiss. “Eat Dirt—The Hygiene Hypothesis and Allergic Diseases.” New England Journal of Medicine 347 no. 12 (2002):930–931. The hygiene hypothesis was first suggested in 1989 by David Strachan 4 , who observed an inverse relationship between the number of older children in a family and the incidence of hay fever. Although hay fever in children had increased dramatically during the mid-20th century, incidence was significantly lower in families with more children. Strachan proposed that the lower incidence of allergies in large families could be linked to infections acquired from older siblings, suggesting that these infections made children less susceptible to allergies. Strachan also argued that trends toward smaller families and a greater emphasis on cleanliness in the 20th century had decreased exposure to pathogens and thus led to higher overall rates of allergies, asthma, and other immune disorders. 4 D.P. Strachan “Hay Fever, Hygiene, and Household Size.” British Medical Journal 299 no. 6710 (1989):1259. Other researchers have observed an inverse relationship between the incidence of immune disorders and infectious diseases that are now rare in industrialized countries but still common in less industrialized countries. 5 In developed nations, children under the age of 5 years are not exposed to many of the microbes, molecules, and antigens they almost certainly would have encountered a century ago. The lack of early challenges to the immune system by organisms with which humans and their ancestors evolved may result in failures in immune system functioning later in life. 5 H. Okada et al. “The ‘Hygiene Hypothesis’ for Autoimmune and Allergic Diseases: An Update.” Clinical & Experimental Immunology 160 no. 1 (2010):1–9. Type II (Cytotoxic) Hypersensitivities Immune reactions categorized as type II hypersensitivities , or cytotoxic hypersensitivities , are mediated by IgG and IgM antibodies binding to cell-surface antigens or matrix-associated antigens on basement membranes. These antibodies can either activate complement , resulting in an inflammatory response and lysis of the targeted cells, or they can be involved in antibody-dependent cell-mediated cytotoxicity (ADCC) with cytotoxic T cell s. In some cases, the antigen may be a self-antigen, in which case the reaction would also be described as an autoimmune disease . (Autoimmune diseases are described in Autoimmune Disorders ). In other cases, antibodies may bind to naturally occurring, but exogenous, cell-surface molecules such as antigens associated with blood typing found on red blood cells (RBCs). This leads to the coating of the RBCs by antibodies, activation of the complement cascade, and complement-mediated lysis of RBCs, as well as opsonization of RBCs for phagocytosis. Two examples of type II hypersensitivity reactions involving RBCs are hemolytic transfusion reaction (HTR) and hemolytic disease of the newborn (HDN) . These type II hypersensitivity reactions, which will be discussed in greater detail, are summarized in Table 19.4 . Immunohematology is the study of blood and blood-forming tissue in relation to the immune response. Antibody-initiated responses against blood cells are type II hypersensitivities, thus falling into the field of immunohematology . For students first learning about immunohematology, understanding the immunological mechanisms involved is made even more challenging by the complex nomenclature system used to identify different blood-group antigens , often called blood types . The first blood-group antigens either used alphabetical names or were named for the first person known to produce antibodies to the red blood cell antigen (e.g., Kell, Duffy, or Diego). However, in 1980, the International Society of Blood Transfusion (ISBT) Working Party on Terminology created a standard for blood-group terminology in an attempt to more consistently identify newly discovered blood group antigens. New antigens are now given a number and assigned to a blood-group system, collection, or series. However, even with this effort, blood-group nomenclature is still inconsistent. Common Type II Hypersensitivities Common Name Cause Signs and Symptoms Hemolytic disease of the newborn (HDN) IgG from mother crosses the placenta, targeting the fetus’ RBCs for destruction Anemia, edema, enlarged liver or spleen, hydrops (fluid in body cavity), leading to death of newborn in severe cases Hemolytic transfusion reactions (HTR) IgG and IgM bind to antigens on transfused RBCs, targeting donor RBCs for destruction Fever, jaundice, hypotension, disseminated intravascular coagulation, possibly leading to kidney failure and death Table 19.4 ABO Blood Group Incompatibility The recognition that individuals have different blood types was first described by Karl Landsteiner (1868–1943) in the early 1900s, based on his observation that serum from one person could cause a clumping of RBCs from another. These studies led Landsteiner to the identification of four distinct blood types. Subsequent research by other scientists determined that the four blood types were based on the presence or absence of surface carbohydrates “A” and “B,” and this provided the foundation for the ABO blood group system that is still in use today ( Figure 19.4 ). The functions of these antigens are unknown, but some have been associated with normal biochemical functions of the cell. Furthermore, ABO blood types are inherited as alleles (one from each parent), and they display patterns of dominant and codominant inheritance. The alleles for A and B blood types are codominant to each other, and both are dominant over blood type O. Therefore, individuals with genotypes of AA or AO have type A blood and express the A carbohydrate antigen on the surface of their RBCs. People with genotypes of BB or BO have type B blood and express the B carbohydrate antigen on the surface of their RBCs. Those with a genotype of AB have type AB blood and express both A and B carbohydrate antigens on the surface of their RBCs. Finally, individuals with a genotype of OO have type O blood and lack A and B carbohydrate on the surface of their RBCs. It is important to note that the RBCs of all four ABO blood types share a common protein receptor molecule, and it is the addition of specific carbohydrates to the protein receptors that determines A, B, and AB blood types. The genes that are inherited for the A, B, and AB blood types encode enzymes that add the carbohydrate component to the protein receptor. Individuals with O blood type still have the protein receptor but lack the enzymes that would add carbohydrates that would make their red blood cell type A, B, or AB. IgM antibodies in plasma that cross-react with blood group antigens not present on an individual’s own RBCs are called isohemagglutinin s ( Figure 19.4 ). Isohemagglutinins are produced within the first few weeks after birth and persist throughout life. These antibodies are produced in response to exposure to environmental antigens from food and microorganisms. A person with type A blood has A antigens on the surface of their RBCs and will produce anti-B antibodies to environmental antigens that resemble the carbohydrate component of B antigens. A person with type B blood has B antigens on the surface of their RBCs and will produce anti-A antibodies to environmental antigens that are similar to the carbohydrate component of A antigens. People with blood type O lack both A and B antigens on their RBCs and, therefore, produce both anti-A and anti-B antibodies. Conversely, people with AB blood type have both A and B antigens on their RBCs and, therefore, lack anti-A and anti-B antibodies. A patient may require a blood transfusion because they lack sufficient RBCs ( anemia ) or because they have experienced significant loss of blood volume through trauma or disease. Although the blood transfusion is given to help the patient, it is essential that the patient receive a transfusion with matching ABO blood type. A transfusion with an incompatible ABO blood type may lead to a strong, potentially lethal type II hypersensitivity cytotoxic response called hemolytic transfusion reaction (HTR) ( Figure 19.5 ). For instance, if a person with type B blood receives a transfusion of type A blood, their anti-A antibodies will bind to and agglutinate the transfused RBCs. In addition, activation of the classical complement cascade will lead to a strong inflammatory response, and the complement membrane attack complex (MAC) will mediate massive hemolysis of the transfused RBCs. The debris from damaged and destroyed RBCs can occlude blood vessels in the alveoli of the lungs and the glomeruli of the kidneys. Within 1 to 24 hours of an incompatible transfusion, the patient experiences fever, chills, pruritus (itching), urticaria (hives), dyspnea, hemoglobinuria (hemoglobin in the urine), and hypotension (low blood pressure). In the most serious reactions, dangerously low blood pressure can lead to shock, multi-organ failure, and death of the patient. Hospitals, medical centers, and associated clinical laboratories typically use hemovigilance systems to minimize the risk of HTRs due to clerical error. Hemovigilance systems are procedures that track transfusion information from the donor source and blood products obtained to the follow-up of recipient patients. Hemovigilance systems used in many countries identify HTRs and their outcomes through mandatory reporting (e.g., to the Food and Drug Administration in the United States), and this information is valuable to help prevent such occurrences in the future. For example, if an HTR is found to be the result of laboratory or clerical error, additional blood products collected from the donor at that time can be located and labeled correctly to avoid additional HTRs. As a result of these measures, HTR-associated deaths in the United States occur in about one per 2 million transfused units. 6 6 E.C. Vamvakas, M.A. Blajchman. “Transfusion-Related Mortality: The Ongoing Risks of Allogeneic Blood Transfusion and the Available Strategies for Their Prevention.” Blood 113 no. 15 (2009):3406–3417. Rh Factors Many different types of erythrocyte antigen s have been discovered since the description of the ABO red cell antigens. The second most frequently described RBC antigens are Rh factor s, named after the rhesus macaque ( Macaca mulatta ) factors identified by Karl Landsteiner and Alexander Weiner in 1940. The Rh system of RBC antigens is the most complex and immunogenic blood group system, with more than 50 specificities identified to date. Of all the Rh antigens, the one designated Rho (Weiner) or D (Fisher-Race) is the most immunogenic. Cells are classified as Rh positive (Rh+) if the Rho/D antigen is present or as Rh negative (Rh−) if the Rho/D antigen is absent. In contrast to the carbohydrate molecules that distinguish the ABO blood groups and are the targets of IgM isohemagglutinins in HTRs, the Rh factor antigens are proteins. As discussed in B Lymphocytes and Humoral Immunity , protein antigens activate B cells and antibody production through a T-cell–dependent mechanism, and the T H 2 cells stimulate class switching from IgM to other antibody classes. In the case of Rh factor antigens, T H 2 cells stimulate class switching to IgG, and this has important implications for the mechanism of HDN. Like ABO incompatibilities, blood transfusion s from a donor with the wrong Rh factor antigens can cause a type II hypersensitivity HTR. However, in contrast to the IgM isohemagglutinins produced early in life through exposure to environmental antigens, production of anti-Rh factor antibodies requires the exposure of an individual with Rh− blood to Rh+ positive RBCs and activation of a primary antibody response. Although this primary antibody response can cause an HTR in the transfusion patient, the hemolytic reaction would be delayed up to 2 weeks during the extended lag period of a primary antibody response ( B Lymphocytes and Humoral Immunity ). However, if the patient receives a subsequent transfusion with Rh+ RBCs, a more rapid HTR would occur with anti-Rh factor antibody already present in the blood. Furthermore, the rapid secondary antibody response would provide even more anti-Rh factor antibodies for the HTR. Rh factor incompatibility between mother and fetus can also cause a type II hypersensitivity hemolytic reaction, referred to as hemolytic disease of the newborn (HDN) ( Figure 19.6 ). If an Rh− woman carries an Rh+ baby to term, the mother’s immune system can be exposed to Rh+ fetal red blood cells . This exposure will usually occur during the last trimester of pregnancy and during the delivery process. If this exposure occurs, the Rh+ fetal RBCs will activate a primary adaptive immune response in the mother, and anti-Rh factor IgG antibodies will be produced. IgG antibodies are the only class of antibody that can cross the placenta from mother to fetus; however, in most cases, the first Rh+ baby is unaffected by these antibodies because the first exposure typically occurs late enough in the pregnancy that the mother does not have time to mount a sufficient primary antibody response before the baby is born. If a subsequent pregnancy with an Rh+ fetus occurs, however, the mother’s second exposure to the Rh factor antigens causes a strong secondary antibody response that produces larger quantities of anti-Rh factor IgG. These antibodies can cross the placenta from mother to fetus and cause HDN, a potentially lethal condition for the baby ( Figure 19.6 ). Prior to the development of techniques for diagnosis and prevention, Rh factor incompatibility was the most common cause of HDN, resulting in thousands of infant deaths each year worldwide. 7 For this reason, the Rh factors of prospective parents are regularly screened, and treatments have been developed to prevent HDN caused by Rh incompatibility. To prevent Rh factor-mediated HDN, human Rho(D) immune globulin (e.g., RhoGAM ) is injected intravenously or intramuscularly into the mother during the 28th week of pregnancy and within 72 hours after delivery. Additional doses may be administered after events that may result in transplacental hemorrhage (e.g., umbilical blood sampling, chorionic villus sampling, abdominal trauma, amniocentesis). This treatment is initiated during the first pregnancy with an Rh+ fetus. The anti-Rh antibodies in Rho(D) immune globulin will bind to the Rh factor of any fetal RBCs that gain access to the mother’s bloodstream, preventing these Rh+ cells from activating the mother’s primary antibody response. Without a primary anti-Rh factor antibody response, the next pregnancy with an Rh+ will have minimal risk of HDN. However, the mother will need to be retreated with Rho(D) immune globulin during that pregnancy to prevent a primary anti-Rh antibody response that could threaten subsequent pregnancies. 7 G. Reali. “Forty Years of Anti-D Immunoprophylaxis.” Blood Transfusion 5 no. 1 (2007):3–6. Link to Learning Use this interactive Blood Typing Game to reinforce your knowledge of blood typing. Check Your Understanding What happens to cells that possess incompatible antigens in a type II hypersensitivity reaction? Describe hemolytic disease of the newborn and explain how it can be prevented. Clinical Focus Part 2 Kerry’s primary care physician is not sure why Kerry seems to develop rashes after spending time in the sun, so she orders a urinalysis and basic blood tests. The results reveal that Kerry has proteinuria (abnormal protein levels in the urine), hemoglobinuria (excess hemoglobin in the urine), and a low hematocrit (RBC count). These tests suggest that Kerry is suffering from a mild bout of hemolytic anemia. The physician suspects that the problem might be autoimmune, so she refers Kerry to a rheumatologist for additional testing and diagnosis. Rheumatologists specialize in musculoskeletal diseases such as arthritis, osteoporosis, and joint pain. Why might Kerry’s physician refer her to this particular type of specialist even though she is exhibiting none of these symptoms? Jump to the next Clinical Focus box. Go back to the previous Clinical Focus box. Type III Hypersensitivities Type III hypersensitivities are immune-complex reactions that were first characterized by Nicolas Maurice Arthus (1862–1945) in 1903. To produce antibodies for experimental procedures, Arthus immunized rabbits by injecting them with serum from horses. However, while immunizing rabbits repeatedly with horse serum, Arthus noticed a previously unreported and unexpected localized subcutaneous hemorrhage with edema at the site of injection. This reaction developed within 3 to10 hours after injection. This localized reaction to non-self serum proteins was called an Arthus reaction . An Arthus reaction occurs when soluble antigens bind with IgG in a ratio that results in the accumulation of antigen-antibody aggregates called immune complex es. A unique characteristic of type III hypersensitivity is antibody excess (primarily IgG), coupled with a relatively low concentration of antigen, resulting in the formation of small immune complexes that deposit on the surface of the epithelial cells lining the inner lumen of small blood vessels or on the surfaces of tissues ( Figure 19.7 ). This immune complex accumulation leads to a cascade of inflammatory events that include the following: IgG binding to antibody receptors on localized mast cells, resulting in mast-cell degranulation Complement activation with production of pro-inflammatory C3a and C5a (see Chemical Defenses ) Increased blood-vessel permeability with chemotactic recruitment of neutrophils and macrophages Because these immune complexes are not an optimal size and are deposited on cell surfaces, they cannot be phagocytosed in the usual way by neutrophils and macrophages, which, in turn, are often described as “frustrated.” Although phagocytosis does not occur, neutrophil degranulation results in the release of lysosomal enzymes that cause extracellular destruction of the immune complex, damaging localized cells in the process. Activation of coagulation pathways also occurs, resulting in thrombi (blood clots) that occlude blood vessels and cause ischemia that can lead to vascular necrosis and localized hemorrhage. Systemic type III hypersensitivity ( serum sickness ) occurs when immune complexes deposit in various body sites, resulting in a more generalized systemic inflammatory response. These immune complexes involve non-self proteins such as antibodies produced in animals for artificial passive immunity (see Vaccines ), certain drugs, or microbial antigens that are continuously released over time during chronic infections (e.g., subacute bacterial endocarditis , chronic viral hepatitis ). The mechanisms of serum sickness are similar to those described in localized type III hypersensitivity but involve widespread activation of mast cells, complement, neutrophils, and macrophages, which causes tissue destruction in areas such as the kidneys, joints, and blood vessels. As a result of tissue destruction, symptoms of serum sickness include chills, fever, rash, vasculitis, and arthritis . Development of glomerulonephritis or hepatitis is also possible. Autoimmune diseases such as systemic lupus erythematosus (SLE) and rheumatoid arthritis can also involve damaging type III hypersensitivity reactions when auto-antibodies form immune complexes with self antigens. These conditions are discussed in Autoimmune Disorders . Check Your Understanding Why is antibody excess important in type III hypersensitivity? Describe the differences between the Arthus reaction and serum sickness. Micro Connections Diphtheria Antitoxin Antibacterial sera are much less commonly used now than in the past, having been replaced by toxoid vaccines. However, a diphtheria antitoxin produced in horses is one example of such a treatment that is still used in some parts of the world. Although it is not licensed by the FDA for use in the United States, diphtheria antitoxin can be used to treat cases of diphtheria, which are caused by the bacterium Corynebacterium diphtheriae . 8 The treatment is not without risks, however. Serum sickness can occur when the patient develops an immune response to non-self horse proteins. Immune complexes are formed between the horse proteins and circulating antibodies when the two exist in certain proportions. These immune complexes can deposit in organs, causing damage such as arthritis, nephritis, rash, and fever. Serum sickness is usually transient with no permanent damage unless the patient is chronically exposed to the antigen, which can then result in irreversible damage to body sites such as joints and kidneys. Over time, phagocytic cells such as macrophages are able to clear the horse serum antigens, which results in improvement of the patient’s condition and a decrease in symptoms as the immune response dissipates. 8 Centers for Disease Control and Prevention. “Diphtheria Antitoxin.” http://www.cdc.gov/diphtheria/dat.html. Accessed March 25, 2016. Clinical Focus Part 3 Kerry does not make it to the rheumatologist. She has a seizure as she is leaving her primary care physician’s office. She is quickly rushed to the emergency department, where her primary care physician relates her medical history and recent test results. The emergency department physician calls in the rheumatologist on staff at the hospital for consultation. Based on the symptoms and test results, the rheumatologist suspects that Kerry has lupus and orders a pair of blood tests: an antinuclear antibody test (ANA) to look for antibodies that bind to DNA and another test that looks for antibodies that bind to a self-antigen called the Smith antigen (Sm). Based on the blood tests ordered, what type of reaction does the rheumatologist suspect is causing Kerry’s seizure? Jump to the next Clinical Focus box. Go back to the previous Clinical Focus box. Type IV Hypersensitivities Type IV hypersensitivities are not mediated by antibodies like the other three types of hypersensitivities. Rather, type IV hypersensitivities are regulated by T cells and involve the action of effector cells. These types of hypersensitivities can be organized into three subcategories based on T-cell subtype, type of antigen, and the resulting effector mechanism ( Table 19.5 ). In the first type IV subcategory, CD4 T H 1-mediated reactions are described as delayed-type hypersensitivities (DTH) . The sensitization step involves the introduction of antigen into the skin and phagocytosis by local antigen presenting cells (APCs) . The APCs activate helper T cells, stimulating clonal proliferation and differentiation into memory T H 1 cells. Upon subsequent exposure to the antigen, these sensitized memory T H 1 cells release cytokines that activate macrophages, and activated macrophages are responsible for much of the tissue damage. Examples of this T H 1-mediated hypersensitivity are observed in tuberculin the Mantoux skin test and contact dermatitis , such as occurs in latex allergy reactions. In the second type IV subcategory, CD4 T H 2-mediated reactions result in chronic asthma or chronic allergic rhinitis . In these cases, the soluble antigen is first inhaled, resulting in eosinophil recruitment and activation with the release of cytokines and inflammatory mediators. In the third type IV subcategory, CD8 cytotoxic T lymphocyte (CTL)-mediated reactions are associated with tissue transplant rejection and contact dermatitis ( Figure 19.8 ). For this form of cell-mediated hypersensitivity, APCs process and present the antigen with MHC I to naïve CD8 T cells. When these naïve CD8 T cells are activated, they proliferate and differentiate into CTLs. Activated T H 1 cells can also enhance the activation of the CTLs. The activated CTLs then target and induce granzyme -mediated apoptosis in cells presenting the same antigen with MHC I. These target cells could be “self” cells that have absorbed the foreign antigen (such as with contact dermatitis due to poison ivy), or they could be transplanted tissue cells displaying foreign antigen from the donor. Type IV Hypersensitivities Subcategory Antigen Effector Mechanism Examples 1 Soluble antigen Activated macrophages damage tissue and promote inflammatory response Contact dermatitis (e.g., exposure to latex) and delayed-type hypersensitivity (e.g., tuberculin reaction) 2 Soluble antigen Eosinophil recruitment and activation release cytokines and pro-inflammatory chemicals Chronic asthma and chronic allergic rhinitis 3 Cell-associated antigen CTL-mediated cytotoxicity Contact dermatitis (e.g., contact with poison ivy) and tissue-transplant rejection Table 19.5 Check Your Understanding Describe the three subtypes of type IV hypersensitivity. Explain how T cells contribute to tissue damage in type IV hypersensitivity. Micro Connections Using Delayed Hypersensitivity to Test for TB Austrian pediatrician Clemans von Pirquet (1874–1929) first described allergy mechanisms, including type III serum sickness. 9 His interest led to the development of a test for tuberculosis (TB), using the tuberculin antigen, based on earlier work identifying the TB pathogen performed by Robert Koch. Pirquet’s method involved scarification, which results in simultaneous multiple punctures, using a device with an array of needles to break the skin numerous times in a small area. The device Pirquet used was similar to the tine test device with four needles seen in Figure 19.9 . 9 B. Huber “100 Jahre Allergie: Clemens von Pirquet–sein Allergiebegriff und das ihm zugrunde liegende Krankheitsverständnis.” Wiener Klinische Wochenschrift 118 no. 19–20 (2006):573–579. The tips of all the needles in the array are coated with tuberculin, a protein extract of TB bacteria, effectively introducing the tuberculin into the skin. One to 3 days later, the area can be examined for a delayed hypersensitivity reaction, signs of which include swelling and redness. As you can imagine, scarification was not a pleasant experience, 10 and the numerous skin punctures put the patient at risk of developing bacterial infection of the skin. Mantoux modified Pirquet’s test to use a single subcutaneous injection of purified tuberculin material. A positive test, which is indicated by a delayed localized swelling at the injection site, does not necessarily mean that the patient is currently infected with active TB. Because type IV (delayed-type) hypersensitivity is mediated by reactivation of memory T cells, such cells may have been created recently (due to an active current infection) or years prior (if a patient had TB and had spontaneously cleared it, or if it had gone into latency). However, the test can be used to confirm infection in cases in which symptoms in the patient or findings on a radiograph suggest its presence. 10 C.A. Stewart. “The Pirquet Test: Comparison of the Scarification and the Puncture Methods of Application.” Archives of Pediatrics & Adolescent Medicine 35 no. 3 (1928):388–391. Hypersensitivity Pneumonitis Some disease caused by hypersensitivities are not caused exclusively by one type. For example, hypersensitivity pneumonitis (HP) , which is often an occupational or environmental disease, occurs when the lungs become inflamed due to an allergic reaction to inhaled dust, endospores, bird feathers, bird droppings, molds, or chemicals. HP goes by many different names associated with various forms of exposure ( Figure 19.10 ). HP associated with bird droppings is sometimes called pigeon fancier’s lung or poultry worker’s lung —both common in bird breeders and handlers. Cheese handler’s disease , farmer’s lung , sauna takers' disease , and hot-tub lung are other names for HP associated with exposure to molds in various environments. Pathology associated with HP can be due to both type III (mediated by immune complexes) and type IV (mediated by T H 1 cells and macrophages) hypersensitivities. Repeated exposure to allergens can cause alveolitis due to the formation of immune complexes in the alveolar wall of the lung accompanied by fluid accumulation, and the formation of granuloma s and other lesions in the lung as a result of T H 1-mediated macrophage activation. Alveolitis with fluid and granuloma formation results in poor oxygen perfusion in the alveoli, which, in turn, can cause symptoms such as coughing, dyspnea, chills, fever, sweating, myalgias, headache, and nausea. Symptoms may occur as quickly as 2 hours after exposure and can persist for weeks if left untreated. Check Your Understanding Explain why hypersensitivity pneumonitis is considered an occupational disease. Figure 19.11 summarizes the mechanisms and effects of each type of hypersensitivity discussed in this section. Diagnosis of Hypersensitivities Diagnosis of type I hypersensitivities is a complex process requiring several diagnostic tests in addition to a well-documented patient history. Serum IgE levels can be measured, but elevated IgE alone does not confirm allergic disease. As part of the process to identify the antigens responsible for a type I reaction allergy, testing through a prick puncture skin test (PPST) or an intradermal test can be performed. PPST is carried out with the introduction of allergens in a series of superficial skin pricks on the patient’s back or arms ( Figure 19.12 ). PPSTs are considered to be the most convenient and least expensive way to diagnose allergies, according to the US Joint Council of Allergy and the European Academy of Allergy and Immunology. The second type of testing, the intradermal test, requires injection into the dermis with a small needle. This needle, also known as a tuberculin needle, is attached to a syringe containing a small amount of allergen. Both the PPST and the intradermal tests are observed for 15–20 minutes for a wheal-flare reaction to the allergens. Measurement of any wheal (a raised, itchy bump) and flare (redness) within minutes indicates a type I hypersensitivity, and the larger the wheal-flare reaction, the greater the patient’s sensitivity to the allergen. Type III hypersensitivities can often be misdiagnosed because of their nonspecific inflammatory nature. The symptoms are easily visible, but they may be associated with any of a number of other diseases. A strong, comprehensive patient history is crucial to proper and accurate diagnosis. Tests used to establish the diagnosis of hypersensitivity pneumonitis (resulting from type III hypersensitivity) include bronchoalveolar lavage (BAL), pulmonary function tests, and high-resolution computed tomography (HRCT) . Check Your Understanding Describe the prick puncture skin test. Explain why type III hypersensitivities can be difficult to diagnose. Treatments of Hypersensitivities Allergic reactions can be treated in various ways. Prevention of allergic reactions can be achieved by desensitization ( hyposensitization ) therapy, which can be used to reduce the hypersensitivity reaction through repeated injections of allergens. Extremely dilute concentrations of known allergens (determined from the allergen tests) are injected into the patient at prescribed intervals (e.g., weekly). The quantity of allergen delivered by the shots is slowly increased over a buildup period until an effective dose is determined and that dose is maintained for the duration of treatment, which can last years. Patients are usually encouraged to remain in the doctor’s office for 30 minutes after receiving the injection in case the allergens administered cause a severe systemic reaction. Doctors’ offices that administer desensitization therapy must be prepared to provide resuscitation and drug treatment in the case of such an event. Desensitization therapy is used for insect sting allergies and environmental allergies. The allergy shots elicit the production of different interleukins and IgG antibody responses instead of IgE. When excess allergen-specific IgG antibodies are produced and bind to the allergen, they can act as blocking antibodies to neutralize the allergen before it can bind IgE on mast cells. There are early studies using oral therapy for desensitization of food allergies that are promising. 11 12 These studies involve feeding children who have allergies tiny amounts of the allergen (e.g., peanut flour) or related proteins over time. Many of the subjects show reduced severity of reaction to the food allergen after the therapy. 11 C.L. Schneider et al. “A Pilot Study of Omalizumab to Facilitate Rapid Oral Desensitization in High-Risk Peanut-Allergic Patients.” Journal of Allergy and Clinical Immunology 132 no. 6 (2013):1368–1374. 12 P. Varshney et al. “A Randomized Controlled Study of Peanut Oral Immunotherapy: Clinical Desensitization and Modulation of the Allergic Response.” Journal of Allergy and Clinical Immunology 127 no. 3 (2011):654–660. There are also therapies designed to treat severe allergic reactions. Emergency systemic anaphylaxis is treated initially with an epinephrine injection, which can counteract the drop in blood pressure. Individuals with known severe allergies often carry a self-administering auto-injector that can be used in case of exposure to the allergen (e.g., an insect sting or accidental ingestion of a food that causes a severe reaction). By self-administering an epinephrine shot (or sometimes two), the patient can stem the reaction long enough to seek medical attention. Follow-up treatment generally involves giving the patient antihistamine s and slow-acting corticosteroid s for several days after the reaction to prevent potential late-phase reactions. However, the effects of antihistamine and corticosteroid treatment are not well studied and are used based on theoretical considerations. Treatment of milder allergic reactions typically involves antihistamines and other anti-inflammatory drugs. A variety of antihistamine drugs are available, in both prescription and over-the-counter strengths. There are also antileukotriene and antiprostaglandin drugs that can be used in tandem with antihistamine drugs in a combined (and more effective) therapy regime. Treatments of type III hypersensitivities include preventing further exposure to the antigen and the use of anti-inflammatory drugs. Some conditions can be resolved when exposure to the antigen is prevented. Anti-inflammatory corticosteroid inhalers can also be used to diminish inflammation to allow lung lesions to heal. Systemic corticosteroid treatment, oral or intravenous, is also common for type III hypersensitivities affecting body systems. Treatment of hypersensitivity pneumonitis includes avoiding the allergen, along with the possible addition of prescription steroids such as prednisone to reduce inflammation. Treatment of type IV hypersensitivities includes antihistamines, anti-inflammatory drugs, analgesics, and, if possible, eliminating further exposure to the antigen. Check Your Understanding Describe desensitization therapy. Explain the role of epinephrine in treatment of hypersensitivity reactions. 19.2 Autoimmune Disorders Learning Objectives Explain why autoimmune disorders develop Provide a few examples of organ-specific and systemic autoimmune diseases In 1970, artist Walt Kelly developed a poster promoting Earth Day, featuring a character from Pogo , his daily newspaper comic strip. In the poster, Pogo looks out across a litter-strewn forest and says wryly, “We have met the enemy and he is us.” Pogo was not talking about the human immune system, but he very well could have been. Although the immune system protects the body by attacking invading “enemies” (pathogens), in some cases, the immune system can mistakenly identify the body’s own cells as the enemy, resulting in autoimmune disease . Autoimmune diseases are those in which the body is attacked by its own specific adaptive immune response. In normal, healthy states, the immune system induces tolerance , which is a lack of an anti-self immune response. However, with autoimmunity, there is a loss of immune tolerance, and the mechanisms responsible for autoimmune diseases include type II, III, and IV hypersensitivity reactions. Autoimmune diseases can have a variety of mixed symptoms that flare up and disappear, making diagnosis difficult. The causes of autoimmune disease are a combination of the individual's genetic makeup and the effect of environmental influences, such as sunlight, infections, medications, and environmental chemicals. However, the vagueness of this list reflects our poor understanding of the etiology of these diseases. Except in a very few specific diseases, the initiation event(s) of most autoimmune states has not been fully characterized. There are several possible causes for the origin of autoimmune diseases and autoimmunity is likely due to several factors. Evidence now suggests that regulatory T and B cells play an essential role in the maintenance of tolerance and prevention of autoimmune responses. The regulatory T cells are especially important for inhibiting autoreactive T cells that are not eliminated during thymic selection and escape the thymus (see T Lymphocytes and Cellular Immunity ). In addition, antigen mimicry between pathogen antigens and our own self antigens can lead to cross-reactivity and autoimmunity. Hidden self-antigens may become exposed because of trauma, drug interactions, or disease states, and trigger an autoimmune response. All of these factors could contribute to autoimmunity. Ultimately, damage to tissues and organs in the autoimmune disease state comes as a result of inflammatory responses that are inappropriate; therefore, treatment often includes immunosuppressive drugs and corticosteroid s. Organ-Specific Autoimmune Diseases Some autoimmune diseases are considered organ specific, meaning that the immune system targets specific organs or tissues. Examples of organ-specific autoimmune diseases include celiac disease, Graves disease, Hashimoto thyroiditis, type I diabetes mellitus, and Addison disease. Celiac Disease Celiac disease is largely a disease of the small intestine, although other organs may be affected. People in their 30s and 40s, and children are most commonly affected, but celiac disease can begin at any age. It results from a reaction to proteins, commonly called gluten , found mainly in wheat, barley, rye, and some other grains. The disease has several genetic causes (predispositions) and poorly understood environmental influences. On exposure to gluten, the body produces various autoantibodies and an inflammatory response. The inflammatory response in the small intestine leads to a reduction in the depth of the microvilli of the mucosa, which hinders absorption and can lead to weight loss and anemia. The disease is also characterized by diarrhea and abdominal pain, symptoms that are often misdiagnosed as irritable bowel syndrome . Diagnosis of celiac disease is accomplished from serological tests for the presence of primarily IgA antibodies to components of gluten, the transglutinaminase enzyme, and autoantibodies to endomysium , a connective tissue surrounding muscle fibers. Serological tests are typically followed up with endoscopy and biopsy of the duodenal mucosa. Serological screening surveys have found about 1% of individuals in the United Kingdom are positive even though they do not all display symptoms. 13 This early recognition allows for more careful monitoring and prevention of severe disease. 13 D.A. Van Heel, J. West. “Recent Advances in Coeliac Disease.” Gut 55 no. 7 (2006):1037—1046. Celiac disease is treated with complete removal of gluten-containing foods from the diet, which results in improved symptoms and reduced risk of complications. Other theoretical approaches include breeding grains that do not contain the immunologically reactive components or developing dietary supplements that contain enzymes that break down the protein components that cause the immune response. 14 14 ibid. Disorders of the Thyroid Graves disease is the most common cause of hyperthyroidism in the United States. Symptoms of Graves disease result from the production of thyroid-stimulating immunoglobulin (TSI) also called TSH-receptor antibody . TSI targets and binds to the receptor for thyroid stimulating hormone (TSH) , which is naturally produced by the pituitary gland . TSI may cause conflicting symptoms because it may stimulate the thyroid to make too much thyroid hormone or block thyroid hormone production entirely, making diagnosis more difficult. Signs and symptoms of Graves disease include heat intolerance, rapid and irregular heartbeat, weight loss, goiter (a swollen thyroid gland, protruding under the skin of the throat [ Figure 19.13 ]) and exophthalmia (bulging eyes) often referred to as Graves ophthalmopathy ( Figure 19.14 ). The most common cause of hypothyroidism in the United States is Hashimoto thyroiditis , also called chronic lymphocytic thyroiditis . Patients with Hashimoto thyroiditis often develop a spectrum of different diseases because they are more likely to develop additional autoimmune diseases such as Addison disease (discussed later in this section), type 1 diabetes, rheumatoid arthritis, and celiac disease. Hashimoto thyroiditis is a T H 1 cell-mediated disease that occurs when the thyroid gland is attacked by cytotoxic lymphocytes, macrophages, and autoantibodies. This autoimmune response leads to numerous symptoms that include goiter ( Figure 19.13 ), cold intolerance, muscle weakness, painful and stiff joints, depression, and memory loss. Type 1 Diabetes Juvenile diabetes , or type 1 diabetes mellitus , is usually diagnosed in children and young adults. It is a T-cell-dependent autoimmune disease characterized by the selective destruction of the β cells of the islets of Langerhans in the pancreas by CD4 T H 1-mediated CD8 T cells, anti-β-cell antibodies, and macrophage activity. There is also evidence that viral infections can have either a potentiating or inhibitory role in the development of type 1 diabetes (T1D) mellitus. The destruction of the β cells causes a lack of insulin production by the pancreas. In T1D, β-cell destruction may take place over several years, but symptoms of hyperglycemia , extreme increase in thirst and urination, weight loss, and extreme fatigue usually have a sudden onset, and diagnosis usually does not occur until most β cells have already been destroyed. Autoimmune Addison Disease Destruction of the adrenal glands (the glands lying above the kidneys that produce glucocorticoids, mineralocorticoids, and sex steroids) is the cause of Addison disease , also called primary adrenal insufficiency (PAI) . Today, up to 80% of Addison disease cases are diagnosed as autoimmune Addison disease (AAD), which is caused by an autoimmune response to adrenal tissues disrupting adrenal function. Disruption of adrenal function causes impaired metabolic processes that require normal steroid hormone levels, causing signs and symptoms throughout the body. There is evidence that both humoral and CD4 T H 1-driven CD8 T-cell–mediated immune mechanisms are directed at the adrenal cortex in AAD. There is also evidence that the autoimmune response is associated with autoimmune destruction of other endocrine glands as well, such as the pancreas and thyroid , conditions collectively referred to as autoimmune polyendocrine syndromes (APS) . In up to 80% of patients with AAD, antibodies are produced to three enzymes involved in steroid synthesis: 21-hydroxylase (21-OH), 17α-hydroxylase, and cholesterol side-chain–cleaving enzyme. 15 The most common autoantibody found in AAD is to 21-OH, and antibodies to any of the key enzymes for steroid production are diagnostic for AAD. The adrenal cortex cells are targeted, destroyed, and replaced with fibrous tissue by immune-mediated inflammation. In some patients, at least 90% of the adrenal cortex is destroyed before symptoms become diagnostic. 15 P. Martorell et al. “Autoimmunity in Addison’s Disease.” Netherlands Journal of Medicine 60 no. 7 (2002):269—275. Symptoms of AAD include weakness, nausea, decreased appetite, weight loss, hyperpigmentation ( Figure 19.15 ), hyperkalemia (elevated blood potassium levels), hyponatremia (decreased blood sodium levels), hypoglycemia (decreased levels of blood sugar), hypotension (decreased blood pressure), anemia , lymphocytosis (decreased levels of white blood cells), and fatigue. Under extreme stress, such as surgery, accidental trauma, or infection, patients with AAD may experience an adrenal crisis that causes the patient to vomit, experience abdominal pain, back or leg cramps, and even severe hypotension leading to shock. Check Your Understanding What are the names of autoimmune diseases that interfere with hormone gland function? Describe how the mechanisms of Graves disease and Hashimoto thyroiditis differ. Name the cells that are destroyed in type 1 diabetes mellitus and describe the result. Systemic Autoimmune Diseases Whereas organ-specific autoimmune diseases target specific organs or tissues, systemic autoimmune disease s are more generalized, targeting multiple organs or tissues throughout the body. Examples of systemic autoimmune diseases include multiple sclerosis, myasthenia gravis, psoriasis, rheumatoid arthritis, and systemic lupus erythematosus. Multiple Sclerosis Multiple sclerosis (MS) is an autoimmune central nervous system disease that affects the brain and spinal cord. Lesions in multiple locations within the central nervous system are a hallmark of multiple sclerosis and are caused by infiltration of immune cells across the blood-brain barrier . The immune cells include T cells that promote inflammation, demyelination , and neuron degeneration, all of which disrupt neuronal signaling. Symptoms of MS include visual disturbances; muscle weakness; difficulty with coordination and balance; sensations such as numbness, prickling, or “pins and needles”; and cognitive and memory problems. Myasthenia Gravis Autoantibodies directed against acetylcholine receptors (AChRs) in the synaptic cleft of neuromuscular junctions lead to myasthenia gravis ( Figure 19.16 ). Anti-AChR antibodies are high-affinity IgGs and their synthesis requires activated CD4 T cells to interact with and stimulate B cells. Once produced, the anti-AChR antibodies affect neuromuscular transmission by at least three mechanisms: Complement binding and activation at the neuromuscular junction Accelerated AChR endocytosis of molecules cross-linked by antibodies Functional AChR blocking, which prevents normal acetylcholine attachment to, and activation of, AChR Regardless of the mechanism, the effect of anti-AChR is extreme muscle weakness and potentially death through respiratory arrest in severe cases. Psoriasis Psoriasis is a skin disease that causes itchy or sore patches of thick, red skin with silvery scales on elbows, knees, scalp, back, face, palms, feet, and sometimes other areas. Some individuals with psoriasis also get a form of arthritis called psoriatic arthritis , in which the joints can become inflamed. Psoriasis results from the complex interplay between keratinocytes, dendritic cells, and T cells, and the cytokines produced by these various cells. In a process called cell turnover, skin cells that grow deep in the skin rise to the surface. Normally, this process takes a month. In psoriasis, as a result of cytokine activation, cell turnover happens in just a few days. The thick inflamed patches of skin that are characteristic of psoriasis develop because the skin cells rise too fast. Rheumatoid Arthritis The most common chronic inflammatory joint disease is rheumatoid arthritis (RA) ( Figure 19.17 ) and it is still a major medical challenge because of unsolved questions related to the environmental and genetic causes of the disease. RA involves type III hypersensitivity reactions and the activation of CD4 T cells, resulting in chronic release of the inflammatory cytokines IL-1 , IL-6 , and tumor necrosis factor-α ( TNF-α ). The activated CD4 T cells also stimulate the production of rheumatoid factor (RF) antibodies and anticyclic citrullinated peptide antibodies (anti-CCP) that form immune complex es. Increased levels of acute-phase proteins , such as C-reactive protein (CRP) , are also produced as part of the inflammatory process and participate in complement fixation with the antibodies on the immune complexes. The formation of immune complexes and reaction to the immune factors cause an inflammatory process in joints, particularly in the hands, feet, and legs. Diagnosis of RA is based on elevated levels of RF, anti-CCP, quantitative CRP, and the erythrocyte sedimentation rate (ESR) (modified Westergren). In addition, radiographs, ultrasound, or magnetic resonance imaging scans can identify joint damage, such as erosions, a loss of bone within the joint, and narrowing of joint space. Systemic Lupus Erythematosus The damage and pathology of systemic lupus erythematosus (SLE) is caused by type III hypersensitivity reactions. Autoantibodies produced in SLE are directed against nuclear and cytoplasmic proteins. Anti-nuclear antibodies (ANAs) are present in more than 95% of patients with SLE, 16 with additional autoantibodies including anti-double–stranded DNA (ds-DNA) and anti-Sm antibodies (antibodies to small nuclear ribonucleoprotein). Anti-ds-DNA and anti-Sm antibodies are unique to patients with SLE; thus, their presence is included in the classification criteria of SLE. Cellular interaction with autoantibodies leads to nuclear and cellular destruction, with components released after cell death leading to the formation of immune complexes. 16 C.C. Mok, C.S. Lau. “Pathogenesis of Systemic Lupus Erythematosus.” Journal of Clinical Pathology 56 no. 7 (2003):481—490. Because autoantibodies in SLE can target a wide variety of cells, symptoms of SLE can occur in many body locations. However, the most common symptoms include fatigue, fever with no other cause, hair loss, and a sunlight-sensitive "butterfly" or wolf-mask (lupus) rash that is found in about 50% of people with SLE ( Figure 19.18 ). The rash is most often seen over the cheeks and bridge of the nose, but can be widespread. Other symptoms may appear depending on affected areas. The joints may be affected, leading to arthritis of the fingers, hands, wrists, and knees. Effects on the brain and nervous system can lead to headaches, numbness, tingling, seizures, vision problems, and personality changes. There may also be abdominal pain, nausea, vomiting, arrhythmias, shortness of breath, and blood in the sputum. Effects on the skin can lead to additional areas of skin lesions, and vasoconstriction can cause color changes in the fingers when they are cold (Raynaud phenomenon). Effects on the kidneys can lead to edema in the legs and weight gain. A diagnosis of SLE depends on identification of four of 11 of the most common symptoms and confirmed production of an array of autoantibodies unique to SLE. A positive test for ANAs alone is not diagnostic. Check Your Understanding List the ways antibodies contribute to the pathogenesis of myasthenia gravis. Explain why rheumatoid arthritis is considered a type III hypersensitivity. Describe the symptoms of systemic lupus erythematosus and explain why they affect so many different parts of the body. What is recognized as an antigen in myasthenia gravis? Table 19.6 summarizes the causes, signs, and symptoms of select autoimmune diseases. Select Autoimmune Diseases Disease Cause Signs and Symptoms Addison disease Destruction of adrenal gland cells by cytotoxic T cells Weakness, nausea, hypotension, fatigue; adrenal crisis with severe pain in abdomen, lower back, and legs; circulatory system collapse, kidney failure Celiac disease Antibodies to gluten become autoantibodies that target cells of the small intestine Severe diarrhea, abdominal pain, anemia, malnutrition Diabetes mellitus (type I) Cytotoxic T-cell destruction of the insulin-producing β cells of the pancreas Hyperglycemia, extreme increase in thirst and urination, weight loss, extreme fatigue Graves disease Autoantibodies target thyroid-stimulating hormone receptors, resulting in overstimulation of the thyroid Hyperthyroidism with rapid and irregular heartbeat, heat intolerance, weight loss, goiter, exophthalmia Hashimoto thyroiditis Thyroid gland is attacked by cytotoxic T cells, lymphocytes, macrophages, and autoantibodies Thyroiditis with goiter, cold intolerance, muscle weakness, painful and stiff joints, depression, memory loss Multiple sclerosis (MS) Cytotoxic T-cell destruction of the myelin sheath surrounding nerve axons in the central nervous system Visual disturbances, muscle weakness, impaired coordination and balance, numbness, prickling or “pins and needles” sensations, impaired cognitive function and memory Myasthenia gravis Autoantibodies directed against acetylcholine receptors within the neuromuscular junction Extreme muscle weakness eventually leading to fatal respiratory arrest Psoriasis Cytokine activation of keratinocytes causes rapid and excessive epidermal cell turnover Itchy or sore patches of thick, red skin with silvery scales; commonly affects elbows, knees, scalp, back, face, palms, feet Rheumatoid arthritis Autoantibodies, immune complexes, complement activation, phagocytes, and T cells damage membranes and bone in joints Joint inflammation, pain and disfigurement, chronic systemic inflammation Systemic lupus erythematosus (SLE) Autoantibodies directed against nuclear and cytoplasmic molecules form immune complexes that deposit in tissues. Phagocytic cells and complement activation cause tissue damage and inflammation Fatigue, fever, joint pain and swelling, hair loss, anemia, clotting, a sunlight-sensitive "butterfly" rash, skin lesions, photosensitivity, decreased kidney function, memory loss, confusion, depression Table 19.6 19.3 Organ Transplantation and Rejection Learning Objectives Explain why human leukocyte antigens (HLAs) are important in tissue transplantation Explain the types of grafts possible and their potential for interaction with the immune system Describe what occurs during graft-versus-host disease (GVHD) A graft is the transplantation of an organ or tissue to a different location, with the goal of replacing a missing or damaged organ or tissue. Grafts are typically moved without their attachments to the circulatory system and must reestablish these, in addition to the other connections and interactions with their new surrounding tissues. There are different types of grafts depending on the source of the new tissue or organ. Tissues that are transplanted from one genetically distinct individual to another within the same species are called allograft s . An interesting variant of the allograft is an isograft , in which tissue from one twin is transplanted to another. As long as the twins are monozygotic (therefore, essentially genetically identical), the transplanted tissue is virtually never rejected. If tissues are transplanted from one area on an individual to another area on the same individual (e.g., a skin graft on a burn patient), it is known as an autograft . If tissues from an animal are transplanted into a human, this is called a xenograft . Transplant Rejection The different types of grafts described above have varying risks for rejection ( Table 19.7 ). Rejection occurs when the recipient’s immune system recognizes the donor tissue as foreign (non-self), triggering an immune response. The major histocompatibility complex markers MHC I and MHC II , more specifically identified as human leukocyte antigens (HLAs) , play a role in transplant rejection. The HLAs expressed in tissue transplanted from a genetically different individual or species may be recognized as non-self molecules by the host’s dendritic cells . If this occurs, the dendritic cells will process and present the foreign HLAs to the host’s helper T cells and cytotoxic T cells, thereby activating them. Cytotoxic T cells then target and kill the grafted cells through the same mechanism they use to kill virus-infected cells; helper T cells may also release cytokines that activate macrophages to kill graft cells. Types of Tissue and Organ Grafts and Their Complications Graft Procedure Complications Autograft From self to self No rejection concerns Isograft From identical twin to twin Little concern of rejection Allograft From relative or nonrelative to individual Rejection possible Xenograft From animal to human Rejection possible Table 19.7 With the three highly polymorphic MHC I genes in humans ( HLA-A , HLA-B , and HLA-C ) determining compatibility, each with many alleles segregating in a population, odds are extremely low that a randomly chosen donor will match a recipient's six-allele genotype (the two alleles at each locus are expressed codominantly). This is why a parent or a sibling may be the best donor in many situations—a genetic match between the MHC genes is much more likely and the organ is much less likely to be rejected. Although matching all of the MHC genes can lower the risk for rejection, there are a number of additional gene products that also play a role in stimulating responses against grafted tissue. Because of this, no non-self grafted tissue is likely to completely avoid rejection. However, the more similar the MHC gene match, the more likely the graft is to be tolerated for a longer time. Most transplant recipients, even those with tissues well matched to their MHC genes, require treatment with immunosuppressant drug s for the rest of their lives. This can make them more vulnerable than the general population to complications from infectious diseases. It can also result in transplant-related malignancies because the body’s normal defenses against cancer cells are being suppressed. Check Your Understanding What part of the immune response is responsible for graft rejection? Explain why blood relatives are preferred as organ donors. Describe the role of immunosuppression in transplantation. Graft-versus-Host Disease A form of rejection called graft-versus-host disease (GVHD) primarily occurs in recipients of bone marrow transplant s and peripheral blood stem cells. GHVD presents a unique situation because the transplanted tissue is capable of producing immune cells; APCs in the donated bone marrow may recognize the host cells as non-self, leading to activation of the donor cytotoxic T cells. Once activated, the donor’s T cells attack the recipient cells, causing acute GVHD . Acute GVHD typically develops within weeks after a bone marrow transplant, causing tissue damage affecting the skin, gastrointestinal tract, liver, and eyes. In addition, acute GVHD may also lead to a cytokine storm , an unregulated secretion of cytokines that may be fatal. In addition to acute GVHD, there is also the risk for chronic GVHD developing months after the bone marrow transplant. The mechanisms responsible for chronic GVHD are not well understood. To minimize the risk of GVHD, it is critically important to match the HLAs of the host and donor as closely as possible in bone marrow transplants. In addition, the donated bone marrow is processed before grafting to remove as many donor APCs and T cells as possible, leaving mostly hematopoietic stem cell s. Check Your Understanding Why does GVHD occur in specifically in bone marrow transplants? What cells are responsible for GVHD? The Future of Transplantation Historically speaking, the practice of transplanting tissues—and the complications that can accompany such procedures—is a relatively recent development. It was not until 1954 that the first successful organ transplantation between two humans was achieved. Yet the field of organ transplantation has progressed rapidly since that time. Nonetheless, the practice of transplanting non-self tissues may soon become obsolete. Scientists are now attempting to develop methods by which new organs may be grown in vitro from an individual’s own harvested cells to replace damaged or abnormal ones. Because organs produced in this way would contain the individual’s own cells, they could be transplanted into the individual without risk for rejection. An alternative approach that is gaining renewed research interest is genetic modification of donor animals, such as pigs, to provide transplantable organs that do not elicit an immune response in the recipient. The approach involves excising the genes in the pig (in the embryo) that are most responsible for the rejection reaction after transplantation. Finding these genes and effectively removing them is a challenge, however. So too is identifying and neutralizing risks from viral sequences that might be embedded in the pig genome, posing a risk for infection in the human recipient. Link to Learning There are currently more than a dozen different tissues and organs used in human transplantations. Learn more about them at this website. Clinical Focus Resolution Kerry's tests come back positive, confirming a diagnosis of lupus , a disease that occurs 10 times more frequently in women than men. SLE cannot be cured, but there are various therapies available for reducing and managing its symptoms. Specific therapies are prescribed based on the particular symptoms presenting in the patient. Kerry's rheumatologist starts her therapy with a low dose of corticosteroid s to reduce her rashes. She also prescribes a low dose of hydroxychloroquine, an anti-inflammatory drug that is used to treat inflammation in patients with RA, childhood arthritis, SLE, and other autoimmune diseases. Although the mechanism of action of hydroxychloroquine is not well defined, it appears that this drug interferes with the processes of antigen processing and activation of autoimmunity. Because of its mechanism, the effects of hydroxychloroquine are not as immediate as that of other anti-inflammatory drugs, but it is still considered a good companion therapy for SLE. Kerry’s doctor also advises her to limit her exposure to sunlight, because photosensitivity to sunlight may precipitate rashes. Over the next 6 months, Kerry follows her treatment plan and her symptoms do not return. However, future flare-ups are likely to occur. She will need to continue her treatment for the rest of her life and seek medical attention whenever new symptoms develop. Go back to the previous Clinical Focus box. 19.4 Immunodeficiency Learning Objectives Compare the causes of primary and secondary immunodeficiencies Describe treatments for primary and secondary immunodeficiencies Immunodeficiencies are inherited (primary) or acquired (secondary) disorders in which elements of host immune defenses are either absent or functionally defective. In developed countries, most immunodeficiencies are inherited, and they are usually first seen in the clinic as recurrent or overwhelming infections in infants. However, on a global scale, malnutrition is the most common cause of immunodeficiency and would be categorized as an acquired immunodeficiency. Acquired immunodeficiencies are more likely to develop later in life, and the pathogenic mechanisms of many remain obscure. Primary Immunodeficiency Primary immunodeficiencies, which number more than 250, are caused by inherited defects of either nonspecific innate or specific adaptive immune defenses. In general, patients born with primary immunodeficiency (PI) commonly have an increased susceptibility to infection. This susceptibility can become apparent shortly after birth or in early childhood for some individuals, whereas other patients develop symptoms later in life. Some primary immunodeficiencies are due to a defect of a single cellular or humoral component of the immune system; others may result from defects of more than one component. Examples of primary immunodeficiencies include chronic granulomatous disease, X-linked agammaglobulinemia, selective IgA deficiency, and severe combined immunodeficiency disease. Chronic Granulomatous Disease The causes of chronic granulomatous disease (CGD) are defects in the NADPH oxidase system of phagocytic cells, including neutrophils and macrophages , that prevent the production of superoxide radicals in phagolysosomes. The inability to produce superoxide radicals impairs the antibacterial activity of phagocytes . As a result, infections in patients with CGD persist longer, leading to a chronic local inflammation called a granuloma . Microorganisms that are the most common causes of infections in patients with CGD include Aspergillus spp., Staphylococcus aureus , Chromobacterium violaceum , Serratia marcescens , and Salmonella typhimurium . X-Linked Agammaglobulinemia Deficiencies in B cells due to defective differentiation lead to a lack of specific antibody production known as X-linked agammaglobulinemia . In 1952, Ogden C. Bruton (1908–2003) described the first immunodeficiency in a boy whose immune system failed to produce antibodies. This defect is inherited on the X chromosome and is characterized by the absence of immunoglobulin in the serum; it is called Bruton X-linked agammaglobulinemia (XLA). The defective gene, BTK, in XLA is now known to encode a tyrosine kinase called Bruton tyrosine kinase (Btk). In patients whose B cells are unable to produce sufficient amounts of Btk, the B-cell maturation and differentiation halts at the pre-B-cell stage of growth. B-cell maturation and differentiation beyond the pre-B-cell stage of growth is required for immunoglobulin production. Patients who lack antibody production suffer from recurrent infections almost exclusively due to extracellular pathogens that cause pyogenic infections: Haemophilus influenzae , Streptococcus pneumoniae , S. pyogenes , and S. aureus . Because cell-mediated immunity is not impaired, these patients are not particularly vulnerable to infections caused by viruses or intracellular pathogens. Selective IgA Deficiency The most common inherited form of immunoglobulin deficiency is selective IgA deficiency , affecting about one in 800 people. Individuals with selective IgA deficiency produce normal levels of IgG and IgM, but are not able to produce secretory IgA . IgA deficiency predisposes these individuals to lung and gastrointestinal infections for which secretory IgA is normally an important defense mechanism. Infections in the lungs and gastrointestinal tract can involve a variety of pathogens, including H. influenzae , S. pneumoniae , Moraxella catarrhalis , S. aureus , Giardia lamblia , or pathogenic strains of Escherichia coli . Severe Combined Immunodeficiency Patients who suffer from severe combined immunodeficiency (SCID) have B-cell and T-cell defects that impair T-cell dependent antibody response s as well as cell-mediated immune response s. Patients with SCID also cannot develop immunological memory, so vaccine s provide them no protection, and live attenuated vaccines (e.g., for varicella-zoster, measles virus, rotavirus, poliovirus) can actually cause the infection they are intended to prevent. The most common form is X-linked SCID , which accounts for nearly 50% of all cases and occurs primarily in males. Patients with SCID are typically diagnosed within the first few months of life after developing severe, often life-threatening, opportunistic infection by Candida spp., Pneumocystis jirovecii , or pathogenic strains of E. coli . Without treatment, babies with SCID do not typically survive infancy. In some cases, a bone marrow transplant may successfully correct the defects in lymphocyte development that lead to the SCID phenotype, by replacing the defective component. However, this treatment approach is not without risks, as demonstrated by the famous case of David Vetter (1971–1984), better known as “Bubble Boy” ( Figure 19.19 ). Vetter, a patient with SCID who lived in a protective plastic bubble to prevent exposure to opportunistic microbes, received a bone marrow transplant from his sister. Because of a latent Epstein-Barr virus infection in her bone marrow, however, he developed mononucleosis and died of Burkitt lymphoma at the age of 12 years. Check Your Understanding What is the fundamental cause of a primary immunodeficiency? Explain why patients with chronic granulomatous disease are especially susceptible to bacterial infections. Explain why individuals with selective IgA deficiency are susceptible to respiratory and gastrointestinal infections. Secondary Immunodeficiency A secondary immunodeficiency occurs as a result an acquired impairment of function of B cells, T cells, or both. Secondary immunodeficiencies can be caused by: Systemic disorders such as diabetes mellitus , malnutrition , hepatitis , or HIV infection Immunosuppressive treatments such as cytotoxic chemotherapy , bone marrow ablation before transplantation, or radiation therapy Prolonged critical illness due to infection, surgery, or trauma in the very young, elderly, or hospitalized patients Unlike primary immunodeficiencies, which have a genetic basis, secondary immunodeficiencies are often reversible if the underlying cause is resolved. Patients with secondary immunodeficiencies develop an increased susceptibility to an otherwise benign infection by opportunistic pathogens such as Candida spp., P. jirovecii , and Cryptosporidium . HIV infection and the associated acquired immunodeficiency syndrome (AIDS) are the best-known secondary immunodeficiencies. AIDS is characterized by profound CD4 T-cell lymphopenia (decrease in lymphocytes). The decrease in CD4 T cells is the result of various mechanisms, including HIV-induced pyroptosis (a type of apoptosis that stimulates an inflammatory response), viral cytopathic effect, and cytotoxicity to HIV-infected cells. The most common cause of secondary immunodeficiency worldwide is severe malnutrition, which affects both innate and adaptive immunity. More research and information are needed for the more common causes of secondary immunodeficiency; however, the number of new discoveries in AIDS research far exceeds that of any other single cause of secondary immunodeficiency. AIDS research has paid off extremely well in terms of discoveries and treatments; increased research into the most common cause of immunodeficiency, malnutrition, would likely be as beneficial. Check Your Understanding What is the most common cause of secondary immunodeficiencies? Explain why secondary immunodeficiencies can sometimes be reversed. Case in Point An Immunocompromised Host Benjamin, a 50-year-old male patient who has been receiving chemotherapy to treat his chronic myelogenous leukemia ( CML ), a disease characterized by massive overproduction of nonfunctional, malignant myelocytic leukocytes that crowd out other, healthy leukocytes, is seen in the emergency department. He is complaining of a productive, wet cough, dyspnea, and fatigue. On examination, his pulse is 120 beats per minute (bpm) (normal range is 60–100 bpm) and weak, and his blood pressure is 90/60 mm Hg (normal is 120/80 mm Hg). During auscultation, a distinct crackling can be heard in his lungs as he breathes, and his pulse-oximeter level (a measurement of blood-oxygen saturation) is 80% (normal is 95%–100%). He has a fever; his temperature is 38.9 °C (102 °F). Sputum cultures and blood samples are obtained and sent to the lab, but Benjamin goes into respiratory distress and dies before the results can be obtained. Benjamin’s death was a result of a combination of his immune system being compromised by his leukemia and his chemotherapy treatment further weakening his ability to mount an immune response. CML (and leukemia in general) and corresponding chemotherapy cause a decrease in the number of leukocytes capable of normal function, leading to secondary immunodeficiency. This increases the risk for opportunistic bacterial, viral, protozoal, and fungal infections that could include Staphylococcus , enteroviruses, Pneumocystis , Giardia, or Candida . Benjamin’s symptoms were suggestive of bacterial pneumonia, but his leukemia and chemotherapy likely complicated and contributed to the severity of the pneumonia, resulting in his death. Because his leukemia was overproducing certain white blood cells, and those overproduced white blood cells were largely nonfunctional or abnormal in their function, he did not have the proper immune system blood cells to help him fight off the infection. Table 19.8 summarizes primary and secondary immunodeficiencies, their effects on immune function, and typical outcomes. Primary and Secondary Immunodeficiencies Disease Effect on Immune Function Outcomes Primary immunodeficiencies Chronic granulomatous disease Impaired killing of bacteria within the phagolysosome of neutrophils and macrophages Chronic infections and granulomas Selective IgA deficiency Inability to produce secretory IgA Predisposition to lung and gastrointestinal infections Severe combined immunodeficiency disease (SCID) Deficient humoral and cell-mediated immune responses Early development of severe and life-threatening opportunistic infections X-linked agammaglobulinemia Flawed differentiation of B cells and absence of specific antibodies Recurrent infections almost exclusively due to pathogens that cause pyogenic infections Secondary immunodeficiencies Immunosuppressive therapies (e.g., chemotherapy, radiotherapy) Impaired humoral and/or cell-mediated immune responses Opportunistic infections, rare cancers Malnutrition Impaired humoral and/or cell-mediated immune responses Opportunistic infections, rare cancers Viral infection (e.g., HIV) Impaired cell-mediated immune responses due to CD4 T-cell lymphopenia Opportunistic infections, rare cancers Table 19.8 19.5 Cancer Immunobiology and Immunotherapy Learning Objectives Explain how the adaptive specific immune response responds to tumors Discuss the risks and benefits of tumor vaccines Cancer involves a loss of the ability of cells to control their cell cycle , the stages each eukaryotic cell goes through as it grows and then divides. When this control is lost, the affected cells rapidly divide and often lose the ability to differentiate into the cell type appropriate for their location in the body. In addition, they lose contact inhibition and can start to grow on top of each other. This can result in formation of a tumor . It is important to make a distinction here: The term “ cancer ” is used to describe the diseases resulting from loss of cell-cycle regulation and subsequent cell proliferation. But the term “tumor” is more general. A “tumor” is an abnormal mass of cells, and a tumor can be benign (not cancerous) or malignant (cancerous). Traditional cancer treatment uses radiation and/or chemotherapy to destroy cancer cells; however, these treatments can have unwanted side effects because they harm normal cells as well as cancer cells. Newer, promising therapies attempt to enlist the patient’s immune system to target cancer cells specifically. It is known that the immune system can recognize and destroy cancerous cells, and some researchers and immunologists also believe, based on the results of their experiments, that many cancers are eliminated by the body’s own defenses before they can become a health problem. This idea is not universally accepted by researchers, however, and needs further investigation for verification. Cell-Mediated Response to Tumors Cell-mediated immune responses can be directed against cancer cells, many of which do not have the normal complement of self-proteins, making them a target for elimination. Abnormal cancer cells may also present tumor antigen s. These tumor antigens are not a part of the screening process used to eliminate lymphocytes during development; thus, even though they are self-antigens, they can stimulate and drive adaptive immune responses against abnormal cells. Presentation of tumor antigens can stimulate naïve helper T cells to become activated by cytokines such as IL-12 and differentiate into T H 1 cell s. T H 1 cells release cytokines that can activate natural killer (NK) cells and enhance the killing of activated cytotoxic T cell s. Both NK cell s and cytotoxic T cells can recognize and target cancer cells, and induce apoptosis through the action of perforin s and granzyme s. In addition, activated cytotoxic T cells can bind to cell-surface proteins on abnormal cells and induce apoptosis by a second killing mechanism called the CD95 (Fas) cytotoxic pathway . Despite these mechanisms for removing cancerous cells from the body, cancer remains a common cause of death. Unfortunately, malignant tumors tend to actively suppress the immune response in various ways. In some cancers, the immune cells themselves are cancerous. In leukemia , lymphocytes that would normally facilitate the immune response become abnormal. In other cancers, the cancerous cells can become resistant to induction of apoptosis . This may occur through the expression of membrane proteins that shut off cytotoxic T cells or that induce regulatory T cells that can shut down immune responses. The mechanisms by which cancer cells alter immune responses are still not yet fully understood, and this is a very active area of research. As scientists’ understanding of adaptive immunity improves, cancer therapies that harness the body’s immune defenses may someday be more successful in treating and eliminating cancer. Check Your Understanding How do cancer cells suppress the immune system? Describe how the immune system recognizes and destroys cancer cells. Cancer Vaccines There are two types of cancer vaccines : preventive and therapeutic. Preventive vaccines are used to prevent cancer from occurring, whereas therapeutic vaccines are used to treat patients with cancer. Most preventive cancer vaccines target viral infections that are known to lead to cancer. These include vaccines against human papillomavirus (HPV) and hepatitis B , which help prevent cervical and liver cancer, respectively. Most therapeutic cancer vaccines are in the experimental stage. They exploit tumor-specific antigens to stimulate the immune system to selectively attack cancer cells. Specifically, they aim to enhance T H 1 function and interaction with cytotoxic T cells, which, in turn, results in more effective attack on abnormal tumor cells. In some cases, researchers have used genetic engineering to develop antitumor vaccines in an approach similar to that used for DNA vaccines (see Micro Connections: DNA vaccines ). The vaccine contains a recombinant plasmid with genes for tumor antigens; theoretically, the tumor gene would not induce new cancer because it is not functional, but it could trick the immune system into targeting the tumor gene product as a foreign invader. The first FDA-approved therapeutic cancer vaccine was sipuleucel-T (Provenge) , approved in 2010 to treat certain cases of prostate cancer . 17 This unconventional vaccine is custom designed using the patient’s own cells. APCs are removed from the patient and cultured with a tumor-specific molecule; the cells are then returned to the patient. This approach appears to enhance the patient’s immune response against the cancer cells. Another therapeutic cancer vaccine (talimogene laherparepvec, also called T-VEC or Imlygic ) was approved by the FDA in 2015 for treatment of melanoma , a form of skin cancer. This vaccine contains a virus that is injected into tumors, where it infects and lyses the tumor cells. The virus also induces a response in lesions or tumors besides those into which the vaccine is injected, indicating that it is stimulating a more general (as opposed to local) antitumor immune response in the patient. 17 National Institutes of Health, National Cancer Institute. "Cancer Vaccines." http://www.cancer.gov/about-cancer/causes-prevention/vaccines-fact-sheet#q8. Accessed on May 20, 2016. Check Your Understanding Explain the difference between preventative and therapeutic cancer vaccines. Describe at least two different approaches to developing therapeutic anti-cancer vaccines. Micro Connections Using Viruses to Cure Cancer Viruses typically destroy the cells they infect—a fact responsible for any number of human diseases. But the cell-killing powers of viruses may yet prove to be the cure for some types of cancer, which is generally treated by attempting to rid the body of cancerous cells. Several clinical trials are studying the effects of viruses targeted at cancer cells. Reolysin , a drug currently in testing phases, uses reoviruses (respiratory enteric orphan viruses) that can infect and kill cells that have an activated Ras-signaling pathway, a common mutation in cancerous cells. Viruses such as rubeola (the measles virus) can also be genetically engineered to aggressively attack tumor cells. These modified viruses not only bind more specifically to receptors overexpressed on cancer cells, they also carry genes driven by promoters that are only turned on within cancer cells. Herpesvirus and others have also been modified in this way.
biology
Chapter Outline 19.1 Population Evolution 19.2 Population Genetics 19.3 Adaptive Evolution Introduction All life on Earth is related. Evolutionary theory states that humans, beetles, plants, and bacteria all share a common ancestor, but that millions of years of evolution have shaped each of these organisms into the forms seen today. Scientists consider evolution a key concept to understanding life. Natural selection is one of the most dominant evolutionary forces. Natural selection acts to promote traits and behaviors that increase an organism’s chances of survival and reproduction, while eliminating those traits and behaviors that are to the organism’s detriment. But natural selection can only, as its name implies, select—it cannot create. The introduction of novel traits and behaviors falls on the shoulders of another evolutionary force—mutation. Mutation and other sources of variation among individuals, as well as the evolutionary forces that act upon them, alter populations and species. This combination of processes has led to the world of life we see today.
[ { "answer": { "ans_choice": 2, "ans_text": "Microevolution describes the evolution of organisms in populations, while macroevolution describes the evolution of species over long periods of time." }, "bloom": null, "hl_context": "The mechanisms of inheritance , or genetics , were not understood at the time Charles Darwin and Alfred Russel Wallace were developing their idea of natural selection . This lack of understanding was a stumbling block to understanding many aspects of evolution . In fact , the predominant ( and incorrect ) genetic theory of the time , blending inheritance , made it difficult to understand how natural selection might operate . Darwin and Wallace were unaware of the genetics work by Austrian monk Gregor Mendel , which was published in 1866 , not long after publication of Darwin's book , On the Origin of Species . Mendel ’ s work was rediscovered in the early twentieth century at which time geneticists were rapidly coming to an understanding of the basics of inheritance . Initially , the newly discovered particulate nature of genes made it difficult for biologists to understand how gradual evolution could occur . But over the next few decades genetics and evolution were integrated in what became known as the modern synthesis — the coherent understanding of the relationship between natural selection and genetics that took shape by the 1940s and is generally accepted today . <hl> In sum , the modern synthesis describes how evolutionary processes , such as natural selection , can affect a population ’ s genetic makeup , and , in turn , how this can result in the gradual evolution of populations and species . <hl> <hl> The theory also connects this change of a population over time , called microevolution , with the processes that gave rise to new species and higher taxonomic groups with widely divergent characters , called macroevolution . <hl>", "hl_sentences": "In sum , the modern synthesis describes how evolutionary processes , such as natural selection , can affect a population ’ s genetic makeup , and , in turn , how this can result in the gradual evolution of populations and species . The theory also connects this change of a population over time , called microevolution , with the processes that gave rise to new species and higher taxonomic groups with widely divergent characters , called macroevolution .", "question": { "cloze_format": "The difference between micro- and macroevolution is that ___ .", "normal_format": "What is the difference between micro- and macroevolution?", "question_choices": [ "Microevolution describes the evolution of small organisms, such as insects, while macroevolution describes the evolution of large organisms, like people and elephants.", "Microevolution describes the evolution of microscopic entities, such as molecules and proteins, while macroevolution describes the evolution of whole organisms.", "Microevolution describes the evolution of organisms in populations, while macroevolution describes the evolution of species over long periods of time.", "Microevolution describes the evolution of organisms over their lifetimes, while macroevolution describes the evolution of organisms over multiple generations." ], "question_id": "fs-idm112560656", "question_text": "What is the difference between micro- and macroevolution?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 0, "ans_text": "how selective forces change the allele frequencies in a population over time" }, "bloom": null, "hl_context": "Recall that a gene for a particular character may have several alleles , or variants , that code for different traits associated with that character . For example , in the ABO blood type system in humans , three alleles determine the particular blood-type carbohydrate on the surface of red blood cells . Each individual in a population of diploid organisms can only carry two alleles for a particular gene , but more than two may be present in the individuals that make up the population . Mendel followed alleles as they were inherited from parent to offspring . In the early twentieth century , biologists in a field of study known as population genetics began to study how selective forces change a population through changes in allele and genotypic frequencies . <hl> The allele frequency ( or gene frequency ) is the rate at which a specific allele appears within a population . <hl> Until now we have discussed evolution as a change in the characteristics of a population of organisms , but behind that phenotypic change is genetic change . <hl> In population genetics , the term evolution is defined as a change in the frequency of an allele in a population . <hl> Using the ABO blood type system as an example , the frequency of one of the alleles , I A , is the number of copies of that allele divided by all the copies of the ABO gene in the population . For example , a study in Jordan 1 found a frequency of I A to be 26.1 percent . The I B and I 0 alleles made up 13.4 percent and 60.5 percent of the alleles respectively , and all of the frequencies added up to 100 percent . A change in this frequency over time would constitute evolution in the population . 1 Sahar S . Hanania , Dhia S . Hassawi , and Nidal M . Irshaid , “ Allele Frequency and Molecular Genotypes of ABO Blood Group System in a Jordanian Population , ” Journal of Medical Sciences 7 ( 2007 ): 51-58 , doi : 10.3923 / jms . 2007.51 . 58 . The allele frequency within a given population can change depending on environmental factors ; therefore , certain alleles become more widespread than others during the process of natural selection . Natural selection can alter the population ’ s genetic makeup ; for example , if a given allele confers a phenotype that allows an individual to better survive or have more offspring . Because many of those offspring will also carry the beneficial allele , and often the corresponding phenotype , they will have more offspring of their own that also carry the allele , thus , perpetuating the cycle . Over time , the allele will spread throughout the population . Some alleles will quickly become fixed in this way , meaning that every individual of the population will carry the allele , while detrimental mutations may be swiftly eliminated if derived from a dominant allele from the gene pool . The gene pool is the sum of all the alleles in a population .", "hl_sentences": "The allele frequency ( or gene frequency ) is the rate at which a specific allele appears within a population . In population genetics , the term evolution is defined as a change in the frequency of an allele in a population .", "question": { "cloze_format": "Population genetics is the study of ___.", "normal_format": "The study of what called Population genetics?", "question_choices": [ "how selective forces change the allele frequencies in a population over time", "the genetic basis of population-wide traits", "whether traits have a genetic basis", "the degree of inbreeding in a population" ], "question_id": "fs-idm39131952", "question_text": "Population genetics is the study of:" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 3, "ans_text": "a population undergoing natural selection" }, "bloom": null, "hl_context": "Working under this theory , population geneticists represent different alleles as different variables in their mathematical models . <hl> The variable p , for example , often represents the frequency of a particular allele , say Y for the trait of yellow in Mendel ’ s peas , while the variable q represents the frequency of y alleles that confer the color green . <hl> If these are the only two possible alleles for a given locus in the population , p + q = 1 . In other words , all the p alleles and all the q alleles make up all of the alleles for that locus that are found in the population . But what ultimately interests most biologists is not the frequencies of different alleles , but the frequencies of the resulting genotypes , known as the population ’ s genetic structure , from which scientists can surmise the distribution of phenotypes . If the phenotype is observed , only the genotype of the homozygous recessive alleles can be known ; the calculations provide an estimate of the remaining genotypes . <hl> Since each individual carries two alleles per gene , if the allele frequencies ( p and q ) are known , predicting the frequencies of these genotypes is a simple mathematical calculation to determine the probability of getting these genotypes if two alleles are drawn at random from the gene pool . <hl> <hl> So in the above scenario , an individual pea plant could be pp ( YY ) , and thus produce yellow peas ; pq ( Yy ) , also yellow ; or qq ( yy ) , and thus producing green peas ( Figure 19.2 ) . <hl> <hl> In other words , the frequency of pp individuals is simply p 2 ; the frequency of pq individuals is 2pq ; and the frequency of qq individuals is q 2 . <hl> <hl> And , again , if p and q are the only two possible alleles for a given trait in the population , these genotypes frequencies will sum to one : p 2 + 2pq + q 2 = 1 . <hl> Visual Connection In the early twentieth century , English mathematician Godfrey Hardy and German physician Wilhelm Weinberg stated the principle of equilibrium to describe the genetic makeup of a population . <hl> The theory , which later became known as the Hardy-Weinberg principle of equilibrium , states that a population ’ s allele and genotype frequencies are inherently stable — unless some kind of evolutionary force is acting upon the population , neither the allele nor the genotypic frequencies would change . <hl> The Hardy-Weinberg principle assumes conditions with no mutations , migration , emigration , or selective pressure for or against genotype , plus an infinite population ; while no population can satisfy those conditions , the principle offers a useful model against which to compare real population changes .", "hl_sentences": "The variable p , for example , often represents the frequency of a particular allele , say Y for the trait of yellow in Mendel ’ s peas , while the variable q represents the frequency of y alleles that confer the color green . Since each individual carries two alleles per gene , if the allele frequencies ( p and q ) are known , predicting the frequencies of these genotypes is a simple mathematical calculation to determine the probability of getting these genotypes if two alleles are drawn at random from the gene pool . So in the above scenario , an individual pea plant could be pp ( YY ) , and thus produce yellow peas ; pq ( Yy ) , also yellow ; or qq ( yy ) , and thus producing green peas ( Figure 19.2 ) . In other words , the frequency of pp individuals is simply p 2 ; the frequency of pq individuals is 2pq ; and the frequency of qq individuals is q 2 . And , again , if p and q are the only two possible alleles for a given trait in the population , these genotypes frequencies will sum to one : p 2 + 2pq + q 2 = 1 . The theory , which later became known as the Hardy-Weinberg principle of equilibrium , states that a population ’ s allele and genotype frequencies are inherently stable — unless some kind of evolutionary force is acting upon the population , neither the allele nor the genotypic frequencies would change .", "question": { "cloze_format": "The population that is not in Hardy-Weinberg equilibrium is ___ .", "normal_format": "Which of the following populations is not in Hardy-Weinberg equilibrium?", "question_choices": [ "a population with 12 homozygous recessive individuals (yy), 8 homozygous dominant individuals (YY), and 4 heterozygous individuals (Yy)", "a population in which the allele frequencies do not change over time", "p2 + 2pq + q2 = 1", "a population undergoing natural selection" ], "question_id": "fs-idp1822224", "question_text": "Which of the following populations is not in Hardy-Weinberg equilibrium?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 2, "ans_text": "gene flow" }, "bloom": null, "hl_context": "<hl> Another important evolutionary force is gene flow : the flow of alleles in and out of a population due to the migration of individuals or gametes ( Figure 19.6 ) . <hl> While some populations are fairly stable , others experience more flux . Many plants , for example , send their pollen far and wide , by wind or by bird , to pollinate other populations of the same species some distance away . <hl> Even a population that may initially appear to be stable , such as a pride of lions , can experience its fair share of immigration and emigration as developing males leave their mothers to seek out a new pride with genetically unrelated females . <hl> <hl> This variable flow of individuals in and out of the group not only changes the gene structure of the population , but it can also introduce new genetic variation to populations in different geological locations and habitats . <hl>", "hl_sentences": "Another important evolutionary force is gene flow : the flow of alleles in and out of a population due to the migration of individuals or gametes ( Figure 19.6 ) . Even a population that may initially appear to be stable , such as a pride of lions , can experience its fair share of immigration and emigration as developing males leave their mothers to seek out a new pride with genetically unrelated females . This variable flow of individuals in and out of the group not only changes the gene structure of the population , but it can also introduce new genetic variation to populations in different geological locations and habitats .", "question": { "cloze_format": "When male lions reach sexual maturity, they leave their group in search of a new pride. This can alter the allele frequencies of the population through ___.", "normal_format": "When male lions reach sexual maturity, they leave their group in search of a new pride. This can alter the allele frequencies of the population through which of the following mechanisms?", "question_choices": [ "natural selection", "genetic drift", "gene flow", "random mating" ], "question_id": "fs-idm20960192", "question_text": "When male lions reach sexual maturity, they leave their group in search of a new pride. This can alter the allele frequencies of the population through which of the following mechanisms?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 1, "ans_text": "mutation and gene flow" }, "bloom": null, "hl_context": "<hl> Natural selection is a driving force in evolution and can generate populations that are better adapted to survive and successfully reproduce in their environments . <hl> But natural selection cannot produce the perfect organism . Natural selection can only select on existing variation in the population ; it does not create anything from scratch . <hl> Thus , it is limited by a population ’ s existing genetic variance and whatever new alleles arise through mutation and gene flow . <hl>", "hl_sentences": "Natural selection is a driving force in evolution and can generate populations that are better adapted to survive and successfully reproduce in their environments . Thus , it is limited by a population ’ s existing genetic variance and whatever new alleles arise through mutation and gene flow .", "question": { "cloze_format": "The evolutionary forces that can introduce new genetic variation into a population are ___ .", "normal_format": "Which of the following evolutionary forces can introduce new genetic variation into a population?", "question_choices": [ "natural selection and genetic drift", "mutation and gene flow", "natural selection and nonrandom mating", "mutation and genetic drift" ], "question_id": "fs-idp89063888", "question_text": "Which of the following evolutionary forces can introduce new genetic variation into a population?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 0, "ans_text": "when individuals mate with those who are similar to themselves" }, "bloom": "2", "hl_context": "If individuals nonrandomly mate with their peers , the result can be a changing population . There are many reasons nonrandom mating occurs . One reason is simple mate choice ; for example , female peahens may prefer peacocks with bigger , brighter tails . Traits that lead to more matings for an individual become selected for by natural selection . <hl> One common form of mate choice , called assortative mating , is an individual ’ s preference to mate with partners who are phenotypically similar to themselves . <hl>", "hl_sentences": "One common form of mate choice , called assortative mating , is an individual ’ s preference to mate with partners who are phenotypically similar to themselves .", "question": { "cloze_format": "Assortative mating is ___.", "normal_format": "What is assortative mating?", "question_choices": [ "when individuals mate with those who are similar to themselves", "when individuals mate with those who are dissimilar to themselves", "when individuals mate with those who are the most fit in the population", "when individuals mate with those who are least fit in the population" ], "question_id": "fs-idm68528576", "question_text": "What is assortative mating?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 2, "ans_text": "Inbreeding can bring together rare, deleterious mutations that lead to harmful phenotypes." }, "bloom": "3", "hl_context": "The diversity of alleles and genotypes within a population is called genetic variance . When scientists are involved in the breeding of a species , such as with animals in zoos and nature preserves , they try to increase a population ’ s genetic variance to preserve as much of the phenotypic diversity as they can . <hl> This also helps reduce the risks associated with inbreeding , the mating of closely related individuals , which can have the undesirable effect of bringing together deleterious recessive mutations that can cause abnormalities and susceptibility to disease . <hl> For example , a disease that is caused by a rare , recessive allele might exist in a population , but it will only manifest itself when an individual carries two copies of the allele . Because the allele is rare in a normal , healthy population with unrestricted habitat , the chance that two carriers will mate is low , and even then , only 25 percent of their offspring will inherit the disease allele from both parents . While it is likely to happen at some point , it will not happen frequently enough for natural selection to be able to swiftly eliminate the allele from the population , and as a result , the allele will be maintained at low levels in the gene pool . However , if a family of carriers begins to interbreed with each other , this will dramatically increase the likelihood of two carriers mating and eventually producing diseased offspring , a phenomenon known as inbreeding depression .", "hl_sentences": "This also helps reduce the risks associated with inbreeding , the mating of closely related individuals , which can have the undesirable effect of bringing together deleterious recessive mutations that can cause abnormalities and susceptibility to disease .", "question": { "cloze_format": "When closely related individuals mate with each other, or inbreed, the offspring are often not as fit as the offspring of two unrelated individuals. The reason is that ___ .", "normal_format": "When closely related individuals mate with each other, or inbreed, the offspring are often not as fit as the offspring of two unrelated individuals. Why?", "question_choices": [ "Close relatives are genetically incompatible.", "The DNA of close relatives reacts negatively in the offspring.", "Inbreeding can bring together rare, deleterious mutations that lead to harmful phenotypes.", "Inbreeding causes normally silent alleles to be expressed." ], "question_id": "fs-idm52589200", "question_text": "When closely related individuals mate with each other, or inbreed, the offspring are often not as fit as the offspring of two unrelated individuals. Why?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 3, "ans_text": "gradual geographic variation across an ecological gradient" }, "bloom": null, "hl_context": "Genes are not the only players involved in determining population variation . Phenotypes are also influenced by other factors , such as the environment ( Figure 19.7 ) . A beachgoer is likely to have darker skin than a city dweller , for example , due to regular exposure to the sun , an environmental factor . Some major characteristics , such as sex , are determined by the environment for some species . For example , some turtles and other reptiles have temperature-dependent sex determination ( TSD ) . TSD means that individuals develop into males if their eggs are incubated within a certain temperature range , or females at a different temperature range . Geographic separation between populations can lead to differences in the phenotypic variation between those populations . Such geographical variation is seen between most populations and can be significant . <hl> One type of geographic variation , called a cline , can be seen as populations of a given species vary gradually across an ecological gradient . <hl> Species of warm-blooded animals , for example , tend to have larger bodies in the cooler climates closer to the earth ’ s poles , allowing them to better conserve heat . This is considered a latitudinal cline . Alternatively , flowering plants tend to bloom at different times depending on where they are along the slope of a mountain , known as an altitudinal cline .", "hl_sentences": "One type of geographic variation , called a cline , can be seen as populations of a given species vary gradually across an ecological gradient .", "question": { "cloze_format": "A cline is (a) ___.", "normal_format": "What is a cline?", "question_choices": [ "the slope of a mountain where a population lives", "the degree to which a mutation helps an individual survive", "the number of individuals in the population", "gradual geographic variation across an ecological gradient" ], "question_id": "fs-idp68638704", "question_text": "What is a cline?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 2, "ans_text": "diversifying selection" }, "bloom": "2", "hl_context": "<hl> When the environment changes , populations will often undergo directional selection ( Figure 19.8 ) , which selects for phenotypes at one end of the spectrum of existing variation . <hl> A classic example of this type of selection is the evolution of the peppered moth in eighteenth - and nineteenth-century England . Prior to the Industrial Revolution , the moths were predominately light in color , which allowed them to blend in with the light-colored trees and lichens in their environment . But as soot began spewing from factories , the trees became darkened , and the light-colored moths became easier for predatory birds to spot . Over time , the frequency of the melanic form of the moth increased because they had a higher survival rate in habitats affected by air pollution because their darker coloration blended with the sooty trees . Similarly , the hypothetical mouse population may evolve to take on a different coloration if something were to cause the forest floor where they live to change color . <hl> The result of this type of selection is a shift in the population ’ s genetic variance toward the new , fit phenotype . <hl>", "hl_sentences": "When the environment changes , populations will often undergo directional selection ( Figure 19.8 ) , which selects for phenotypes at one end of the spectrum of existing variation . The result of this type of selection is a shift in the population ’ s genetic variance toward the new , fit phenotype .", "question": { "cloze_format": "The ___ is the selection that results in greater genetic variance in a population.", "normal_format": "The selection that results in greater genetic variance in a population?", "question_choices": [ "stabilizing selection", "directional selection", "diversifying selection", "positive frequency-dependent selection" ], "question_id": "fs-idm31667024", "question_text": "Which type of selection results in greater genetic variance in a population?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 0, "ans_text": "sexual dimorphism" }, "bloom": null, "hl_context": "<hl> Males and females of certain species are often quite different from one another in ways beyond the reproductive organs . <hl> Males are often larger , for example , and display many elaborate colors and adornments , like the peacock ’ s tail , while females tend to be smaller and duller in decoration . <hl> Such differences are known as sexual dimorphisms ( Figure 19.10 ) , which arise from the fact that in many populations , particularly animal populations , there is more variance in the reproductive success of the males than there is of the females . <hl> That is , some males — often the bigger , stronger , or more decorated males — get the vast majority of the total matings , while others receive none . This can occur because the males are better at fighting off other males , or because females will choose to mate with the bigger or more decorated males . In either case , this variation in reproductive success generates a strong selection pressure among males to get those matings , resulting in the evolution of bigger body size and elaborate ornaments to get the females ’ attention . Females , on the other hand , tend to get a handful of selected matings ; therefore , they are more likely to select more desirable males . Sexual dimorphism varies widely among species , of course , and some species are even sex-role reversed . In such cases , females tend to have a greater variance in their reproductive success than males and are correspondingly selected for the bigger body size and elaborate traits usually characteristic of males .", "hl_sentences": "Males and females of certain species are often quite different from one another in ways beyond the reproductive organs . Such differences are known as sexual dimorphisms ( Figure 19.10 ) , which arise from the fact that in many populations , particularly animal populations , there is more variance in the reproductive success of the males than there is of the females .", "question": { "cloze_format": "When males and females of a population look or act differently, it is referred to as ________.", "normal_format": "When males and females of a population look or act differently, what is it referred to?", "question_choices": [ "sexual dimorphism", "sexual selection", "diversifying selection", "a cline" ], "question_id": "fs-idp141728912", "question_text": "When males and females of a population look or act differently, it is referred to as ________." }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 3, "ans_text": "why individuals of one sex develop impressive ornamental traits" }, "bloom": "2", "hl_context": "<hl> The good genes hypothesis states that males develop these impressive ornaments to show off their efficient metabolism or their ability to fight disease . <hl> <hl> Females then choose males with the most impressive traits because it signals their genetic superiority , which they will then pass on to their offspring . <hl> Though it might be argued that females should not be picky because it will likely reduce their number of offspring , if better males father more fit offspring , it may be beneficial . Fewer , healthier offspring may increase the chances of survival more than many , weaker offspring .", "hl_sentences": "The good genes hypothesis states that males develop these impressive ornaments to show off their efficient metabolism or their ability to fight disease . Females then choose males with the most impressive traits because it signals their genetic superiority , which they will then pass on to their offspring .", "question": { "cloze_format": "The good genes hypothesis is a theory that explains ___ .", "normal_format": "The good genes hypothesis is a theory that explains what?", "question_choices": [ "why more fit individuals are more likely to have more offspring", "why alleles that confer beneficial traits or behaviors are selected for by natural selection", "why some deleterious mutations are maintained in the population", "why individuals of one sex develop impressive ornamental traits" ], "question_id": "fs-idp18019456", "question_text": "The good genes hypothesis is a theory that explains what?" }, "references_are_paraphrase": null } ]
19
19.1 Population Evolution Learning Objectives By the end of this section, you will be able to: Define population genetics and describe how population genetics is used in the study of the evolution of populations Define the Hardy-Weinberg principle and discuss its importance The mechanisms of inheritance, or genetics, were not understood at the time Charles Darwin and Alfred Russel Wallace were developing their idea of natural selection. This lack of understanding was a stumbling block to understanding many aspects of evolution. In fact, the predominant (and incorrect) genetic theory of the time, blending inheritance, made it difficult to understand how natural selection might operate. Darwin and Wallace were unaware of the genetics work by Austrian monk Gregor Mendel, which was published in 1866, not long after publication of Darwin's book, On the Origin of Species . Mendel’s work was rediscovered in the early twentieth century at which time geneticists were rapidly coming to an understanding of the basics of inheritance. Initially, the newly discovered particulate nature of genes made it difficult for biologists to understand how gradual evolution could occur. But over the next few decades genetics and evolution were integrated in what became known as the modern synthesis —the coherent understanding of the relationship between natural selection and genetics that took shape by the 1940s and is generally accepted today. In sum, the modern synthesis describes how evolutionary processes, such as natural selection, can affect a population’s genetic makeup, and, in turn, how this can result in the gradual evolution of populations and species. The theory also connects this change of a population over time, called microevolution , with the processes that gave rise to new species and higher taxonomic groups with widely divergent characters, called macroevolution . Everyday Connection Evolution and Flu Vaccines Every fall, the media starts reporting on flu vaccinations and potential outbreaks. Scientists, health experts, and institutions determine recommendations for different parts of the population, predict optimal production and inoculation schedules, create vaccines, and set up clinics to provide inoculations. You may think of the annual flu shot as a lot of media hype, an important health protection, or just a briefly uncomfortable prick in your arm. But do you think of it in terms of evolution? The media hype of annual flu shots is scientifically grounded in our understanding of evolution. Each year, scientists across the globe strive to predict the flu strains that they anticipate being most widespread and harmful in the coming year. This knowledge is based in how flu strains have evolved over time and over the past few flu seasons. Scientists then work to create the most effective vaccine to combat those selected strains. Hundreds of millions of doses are produced in a short period in order to provide vaccinations to key populations at the optimal time. Because viruses, like the flu, evolve very quickly (especially in evolutionary time), this poses quite a challenge. Viruses mutate and replicate at a fast rate, so the vaccine developed to protect against last year’s flu strain may not provide the protection needed against the coming year’s strain. Evolution of these viruses means continued adaptions to ensure survival, including adaptations to survive previous vaccines. Population Genetics Recall that a gene for a particular character may have several alleles, or variants, that code for different traits associated with that character. For example, in the ABO blood type system in humans, three alleles determine the particular blood-type carbohydrate on the surface of red blood cells. Each individual in a population of diploid organisms can only carry two alleles for a particular gene, but more than two may be present in the individuals that make up the population. Mendel followed alleles as they were inherited from parent to offspring. In the early twentieth century, biologists in a field of study known as population genetics began to study how selective forces change a population through changes in allele and genotypic frequencies. The allele frequency (or gene frequency) is the rate at which a specific allele appears within a population. Until now we have discussed evolution as a change in the characteristics of a population of organisms, but behind that phenotypic change is genetic change. In population genetics, the term evolution is defined as a change in the frequency of an allele in a population. Using the ABO blood type system as an example, the frequency of one of the alleles, I A , is the number of copies of that allele divided by all the copies of the ABO gene in the population. For example, a study in Jordan 1 found a frequency of I A to be 26.1 percent. The I B and I 0 alleles made up 13.4 percent and 60.5 percent of the alleles respectively, and all of the frequencies added up to 100 percent. A change in this frequency over time would constitute evolution in the population. 1 Sahar S. Hanania, Dhia S. Hassawi, and Nidal M. Irshaid, “Allele Frequency and Molecular Genotypes of ABO Blood Group System in a Jordanian Population,” Journal of Medical Sciences 7 (2007): 51-58, doi:10.3923/jms.2007.51.58. The allele frequency within a given population can change depending on environmental factors; therefore, certain alleles become more widespread than others during the process of natural selection. Natural selection can alter the population’s genetic makeup; for example, if a given allele confers a phenotype that allows an individual to better survive or have more offspring. Because many of those offspring will also carry the beneficial allele, and often the corresponding phenotype, they will have more offspring of their own that also carry the allele, thus, perpetuating the cycle. Over time, the allele will spread throughout the population. Some alleles will quickly become fixed in this way, meaning that every individual of the population will carry the allele, while detrimental mutations may be swiftly eliminated if derived from a dominant allele from the gene pool. The gene pool is the sum of all the alleles in a population. Sometimes, allele frequencies within a population change randomly with no advantage to the population over existing allele frequencies. This phenomenon is called genetic drift. Natural selection and genetic drift usually occur simultaneously in populations and are not isolated events. It is hard to determine which process dominates because it is often nearly impossible to determine the cause of change in allele frequencies at each occurrence. An event that initiates an allele frequency change in an isolated part of the population, which is not typical of the original population, is called the founder effect . Natural selection, random drift, and founder effects can lead to significant changes in the genome of a population. Hardy-Weinberg Principle of Equilibrium In the early twentieth century, English mathematician Godfrey Hardy and German physician Wilhelm Weinberg stated the principle of equilibrium to describe the genetic makeup of a population. The theory, which later became known as the Hardy-Weinberg principle of equilibrium, states that a population’s allele and genotype frequencies are inherently stable— unless some kind of evolutionary force is acting upon the population, neither the allele nor the genotypic frequencies would change. The Hardy-Weinberg principle assumes conditions with no mutations, migration, emigration, or selective pressure for or against genotype, plus an infinite population; while no population can satisfy those conditions, the principle offers a useful model against which to compare real population changes. Working under this theory, population geneticists represent different alleles as different variables in their mathematical models. The variable p, for example, often represents the frequency of a particular allele, say Y for the trait of yellow in Mendel’s peas, while the variable q represents the frequency of y alleles that confer the color green. If these are the only two possible alleles for a given locus in the population, p + q = 1. In other words, all the p alleles and all the q alleles make up all of the alleles for that locus that are found in the population. But what ultimately interests most biologists is not the frequencies of different alleles, but the frequencies of the resulting genotypes, known as the population’s genetic structure , from which scientists can surmise the distribution of phenotypes. If the phenotype is observed, only the genotype of the homozygous recessive alleles can be known; the calculations provide an estimate of the remaining genotypes. Since each individual carries two alleles per gene, if the allele frequencies (p and q) are known, predicting the frequencies of these genotypes is a simple mathematical calculation to determine the probability of getting these genotypes if two alleles are drawn at random from the gene pool. So in the above scenario, an individual pea plant could be pp (YY), and thus produce yellow peas; pq (Yy), also yellow; or qq (yy), and thus producing green peas ( Figure 19.2 ). In other words, the frequency of pp individuals is simply p 2 ; the frequency of pq individuals is 2pq; and the frequency of qq individuals is q 2 . And, again, if p and q are the only two possible alleles for a given trait in the population, these genotypes frequencies will sum to one: p 2 + 2pq + q 2 = 1. Visual Connection In plants, violet flower color (V) is dominant over white (v). If p = 0.8 and q = 0.2 in a population of 500 plants, how many individuals would you expect to be homozygous dominant (VV), heterozygous (Vv), and homozygous recessive (vv)? How many plants would you expect to have violet flowers, and how many would have white flowers? In theory, if a population is at equilibrium—that is, there are no evolutionary forces acting upon it—generation after generation would have the same gene pool and genetic structure, and these equations would all hold true all of the time. Of course, even Hardy and Weinberg recognized that no natural population is immune to evolution. Populations in nature are constantly changing in genetic makeup due to drift, mutation, possibly migration, and selection. As a result, the only way to determine the exact distribution of phenotypes in a population is to go out and count them. But the Hardy-Weinberg principle gives scientists a mathematical baseline of a non-evolving population to which they can compare evolving populations and thereby infer what evolutionary forces might be at play. If the frequencies of alleles or genotypes deviate from the value expected from the Hardy-Weinberg equation, then the population is evolving. Link to Learning Use this online calculator to determine the genetic structure of a population. 19.2 Population Genetics Learning Objectives By the end of this section, you will be able to: Describe the different types of variation in a population Explain why only heritable variation can be acted upon by natural selection Describe genetic drift and the bottleneck effect Explain how each evolutionary force can influence the allele frequencies of a population Individuals of a population often display different phenotypes, or express different alleles of a particular gene, referred to as polymorphisms. Populations with two or more variations of particular characteristics are called polymorphic. The distribution of phenotypes among individuals, known as the population variation , is influenced by a number of factors, including the population’s genetic structure and the environment ( Figure 19.3 ). Understanding the sources of a phenotypic variation in a population is important for determining how a population will evolve in response to different evolutionary pressures. Genetic Variance Natural selection and some of the other evolutionary forces can only act on heritable traits, namely an organism’s genetic code. Because alleles are passed from parent to offspring, those that confer beneficial traits or behaviors may be selected for, while deleterious alleles may be selected against. Acquired traits, for the most part, are not heritable. For example, if an athlete works out in the gym every day, building up muscle strength, the athlete’s offspring will not necessarily grow up to be a body builder. If there is a genetic basis for the ability to run fast, on the other hand, this may be passed to a child. Link to Learning Before Darwinian evolution became the prevailing theory of the field, French naturalist Jean-Baptiste Lamarck theorized that acquired traits could, in fact, be inherited; while this hypothesis has largely been unsupported, scientists have recently begun to realize that Lamarck was not completely wrong. Visit this site to learn more. Heritability is the fraction of phenotype variation that can be attributed to genetic differences, or genetic variance, among individuals in a population. The greater the hereditability of a population’s phenotypic variation, the more susceptible it is to the evolutionary forces that act on heritable variation. The diversity of alleles and genotypes within a population is called genetic variance . When scientists are involved in the breeding of a species, such as with animals in zoos and nature preserves, they try to increase a population’s genetic variance to preserve as much of the phenotypic diversity as they can. This also helps reduce the risks associated with inbreeding , the mating of closely related individuals, which can have the undesirable effect of bringing together deleterious recessive mutations that can cause abnormalities and susceptibility to disease. For example, a disease that is caused by a rare, recessive allele might exist in a population, but it will only manifest itself when an individual carries two copies of the allele. Because the allele is rare in a normal, healthy population with unrestricted habitat, the chance that two carriers will mate is low, and even then, only 25 percent of their offspring will inherit the disease allele from both parents. While it is likely to happen at some point, it will not happen frequently enough for natural selection to be able to swiftly eliminate the allele from the population, and as a result, the allele will be maintained at low levels in the gene pool. However, if a family of carriers begins to interbreed with each other, this will dramatically increase the likelihood of two carriers mating and eventually producing diseased offspring, a phenomenon known as inbreeding depression . Changes in allele frequencies that are identified in a population can shed light on how it is evolving. In addition to natural selection, there are other evolutionary forces that could be in play: genetic drift, gene flow, mutation, nonrandom mating, and environmental variances. Genetic Drift The theory of natural selection stems from the observation that some individuals in a population are more likely to survive longer and have more offspring than others; thus, they will pass on more of their genes to the next generation. A big, powerful male gorilla, for example, is much more likely than a smaller, weaker one to become the population’s silverback, the pack’s leader who mates far more than the other males of the group. The pack leader will father more offspring, who share half of his genes, and are likely to also grow bigger and stronger like their father. Over time, the genes for bigger size will increase in frequency in the population, and the population will, as a result, grow larger on average. That is, this would occur if this particular selection pressure , or driving selective force, were the only one acting on the population. In other examples, better camouflage or a stronger resistance to drought might pose a selection pressure. Another way a population’s allele and genotype frequencies can change is genetic drift ( Figure 19.4 ), which is simply the effect of chance. By chance, some individuals will have more offspring than others—not due to an advantage conferred by some genetically-encoded trait, but just because one male happened to be in the right place at the right time (when the receptive female walked by) or because the other one happened to be in the wrong place at the wrong time (when a fox was hunting). Visual Connection Do you think genetic drift would happen more quickly on an island or on the mainland? Small populations are more susceptible to the forces of genetic drift. Large populations, on the other hand, are buffered against the effects of chance. If one individual of a population of 10 individuals happens to die at a young age before it leaves any offspring to the next generation, all of its genes—1/10 of the population’s gene pool—will be suddenly lost. In a population of 100, that’s only 1 percent of the overall gene pool; therefore, it is much less impactful on the population’s genetic structure. Link to Learning Go to this site to watch an animation of random sampling and genetic drift in action. Genetic drift can also be magnified by natural events, such as a natural disaster that kills—at random—a large portion of the population. Known as the bottleneck effect , it results in a large portion of the genome suddenly being wiped out ( Figure 19.5 ). In one fell swoop, the genetic structure of the survivors becomes the genetic structure of the entire population, which may be very different from the pre-disaster population. Another scenario in which populations might experience a strong influence of genetic drift is if some portion of the population leaves to start a new population in a new location or if a population gets divided by a physical barrier of some kind. In this situation, those individuals are unlikely to be representative of the entire population, which results in the founder effect. The founder effect occurs when the genetic structure changes to match that of the new population’s founding fathers and mothers. The founder effect is believed to have been a key factor in the genetic history of the Afrikaner population of Dutch settlers in South Africa, as evidenced by mutations that are common in Afrikaners but rare in most other populations. This is likely due to the fact that a higher-than-normal proportion of the founding colonists carried these mutations. As a result, the population expresses unusually high incidences of Huntington’s disease (HD) and Fanconi anemia (FA), a genetic disorder known to cause blood marrow and congenital abnormalities—even cancer. 2 2 A. J. Tipping et al., “Molecular and Genealogical Evidence for a Founder Effect in Fanconi Anemia Families of the Afrikaner Population of South Africa,” PNAS 98, no. 10 (2001): 5734-5739, doi: 10.1073/pnas.091402398. Link to Learning Watch this short video to learn more about the founder and bottleneck effects. Click to view content Scientific Method Connection Testing the Bottleneck Effect Question: How do natural disasters affect the genetic structure of a population? Background: When much of a population is suddenly wiped out by an earthquake or hurricane, the individuals that survive the event are usually a random sampling of the original group. As a result, the genetic makeup of the population can change dramatically. This phenomenon is known as the bottleneck effect. Hypothesis: Repeated natural disasters will yield different population genetic structures; therefore, each time this experiment is run, the results will vary. Test the hypothesis: Count out the original population using different colored beads. For example, red, blue, and yellow beads might represent red, blue, and yellow individuals. After recording the number of each individual in the original population, place them all in a bottle with a narrow neck that will only allow a few beads out at a time. Then, pour 1/3 of the bottle’s contents into a bowl. This represents the surviving individuals after a natural disaster kills a majority of the population. Count the number of the different colored beads in the bowl, and record it. Then, place all of the beads back in the bottle and repeat the experiment four more times. Analyze the data: Compare the five populations that resulted from the experiment. Do the populations all contain the same number of different colored beads, or do they vary? Remember, these populations all came from the same exact parent population. Form a conclusion: Most likely, the five resulting populations will differ quite dramatically. This is because natural disasters are not selective—they kill and spare individuals at random. Now think about how this might affect a real population. What happens when a hurricane hits the Mississippi Gulf Coast? How do the seabirds that live on the beach fare? Gene Flow Another important evolutionary force is gene flow : the flow of alleles in and out of a population due to the migration of individuals or gametes ( Figure 19.6 ). While some populations are fairly stable, others experience more flux. Many plants, for example, send their pollen far and wide, by wind or by bird, to pollinate other populations of the same species some distance away. Even a population that may initially appear to be stable, such as a pride of lions, can experience its fair share of immigration and emigration as developing males leave their mothers to seek out a new pride with genetically unrelated females. This variable flow of individuals in and out of the group not only changes the gene structure of the population, but it can also introduce new genetic variation to populations in different geological locations and habitats. Mutation Mutations are changes to an organism’s DNA and are an important driver of diversity in populations. Species evolve because of the accumulation of mutations that occur over time. The appearance of new mutations is the most common way to introduce novel genotypic and phenotypic variance. Some mutations are unfavorable or harmful and are quickly eliminated from the population by natural selection. Others are beneficial and will spread through the population. Whether or not a mutation is beneficial or harmful is determined by whether it helps an organism survive to sexual maturity and reproduce. Some mutations do not do anything and can linger, unaffected by natural selection, in the genome. Some can have a dramatic effect on a gene and the resulting phenotype. Nonrandom Mating If individuals nonrandomly mate with their peers, the result can be a changing population. There are many reasons nonrandom mating occurs. One reason is simple mate choice; for example, female peahens may prefer peacocks with bigger, brighter tails. Traits that lead to more matings for an individual become selected for by natural selection. One common form of mate choice, called assortative mating , is an individual’s preference to mate with partners who are phenotypically similar to themselves. Another cause of nonrandom mating is physical location. This is especially true in large populations spread over large geographic distances where not all individuals will have equal access to one another. Some might be miles apart through woods or over rough terrain, while others might live immediately nearby. Environmental Variance Genes are not the only players involved in determining population variation. Phenotypes are also influenced by other factors, such as the environment ( Figure 19.7 ). A beachgoer is likely to have darker skin than a city dweller, for example, due to regular exposure to the sun, an environmental factor. Some major characteristics, such as sex, are determined by the environment for some species. For example, some turtles and other reptiles have temperature-dependent sex determination (TSD). TSD means that individuals develop into males if their eggs are incubated within a certain temperature range, or females at a different temperature range. Geographic separation between populations can lead to differences in the phenotypic variation between those populations. Such geographical variation is seen between most populations and can be significant. One type of geographic variation, called a cline , can be seen as populations of a given species vary gradually across an ecological gradient. Species of warm-blooded animals, for example, tend to have larger bodies in the cooler climates closer to the earth’s poles, allowing them to better conserve heat. This is considered a latitudinal cline. Alternatively, flowering plants tend to bloom at different times depending on where they are along the slope of a mountain, known as an altitudinal cline. If there is gene flow between the populations, the individuals will likely show gradual differences in phenotype along the cline. Restricted gene flow, on the other hand, can lead to abrupt differences, even speciation. 19.3 Adaptive Evolution Learning Objectives By the end of this section, you will be able to: Explain the different ways natural selection can shape populations Describe how these different forces can lead to different outcomes in terms of the population variation Natural selection only acts on the population’s heritable traits: selecting for beneficial alleles and thus increasing their frequency in the population, while selecting against deleterious alleles and thereby decreasing their frequency—a process known as adaptive evolution . Natural selection does not act on individual alleles, however, but on entire organisms. An individual may carry a very beneficial genotype with a resulting phenotype that, for example, increases the ability to reproduce (fecundity), but if that same individual also carries an allele that results in a fatal childhood disease, that fecundity phenotype will not be passed on to the next generation because the individual will not live to reach reproductive age. Natural selection acts at the level of the individual; it selects for individuals with greater contributions to the gene pool of the next generation, known as an organism’s evolutionary (Darwinian) fitness . Fitness is often quantifiable and is measured by scientists in the field. However, it is not the absolute fitness of an individual that counts, but rather how it compares to the other organisms in the population. This concept, called relative fitness , allows researchers to determine which individuals are contributing additional offspring to the next generation, and thus, how the population might evolve. There are several ways selection can affect population variation: stabilizing selection, directional selection, diversifying selection, frequency-dependent selection, and sexual selection. As natural selection influences the allele frequencies in a population, individuals can either become more or less genetically similar and the phenotypes displayed can become more similar or more disparate. Stabilizing Selection If natural selection favors an average phenotype, selecting against extreme variation, the population will undergo stabilizing selection ( Figure 19.8 ). In a population of mice that live in the woods, for example, natural selection is likely to favor individuals that best blend in with the forest floor and are less likely to be spotted by predators. Assuming the ground is a fairly consistent shade of brown, those mice whose fur is most closely matched to that color will be most likely to survive and reproduce, passing on their genes for their brown coat. Mice that carry alleles that make them a bit lighter or a bit darker will stand out against the ground and be more likely to fall victim to predation. As a result of this selection, the population’s genetic variance will decrease. Directional Selection When the environment changes, populations will often undergo directional selection ( Figure 19.8 ), which selects for phenotypes at one end of the spectrum of existing variation. A classic example of this type of selection is the evolution of the peppered moth in eighteenth- and nineteenth-century England. Prior to the Industrial Revolution, the moths were predominately light in color, which allowed them to blend in with the light-colored trees and lichens in their environment. But as soot began spewing from factories, the trees became darkened, and the light-colored moths became easier for predatory birds to spot. Over time, the frequency of the melanic form of the moth increased because they had a higher survival rate in habitats affected by air pollution because their darker coloration blended with the sooty trees. Similarly, the hypothetical mouse population may evolve to take on a different coloration if something were to cause the forest floor where they live to change color. The result of this type of selection is a shift in the population’s genetic variance toward the new, fit phenotype. Link to Learning In science, sometimes things are believed to be true, and then new information comes to light that changes our understanding. The story of the peppered moth is an example: the facts behind the selection toward darker moths have recently been called into question. Read this article to learn more. Diversifying Selection Sometimes two or more distinct phenotypes can each have their advantages and be selected for by natural selection, while the intermediate phenotypes are, on average, less fit. Known as diversifying selection ( Figure 19.8 ), this is seen in many populations of animals that have multiple male forms. Large, dominant alpha males obtain mates by brute force, while small males can sneak in for furtive copulations with the females in an alpha male’s territory. In this case, both the alpha males and the “sneaking” males will be selected for, but medium-sized males, which can’t overtake the alpha males and are too big to sneak copulations, are selected against. Diversifying selection can also occur when environmental changes favor individuals on either end of the phenotypic spectrum. Imagine a population of mice living at the beach where there is light-colored sand interspersed with patches of tall grass. In this scenario, light-colored mice that blend in with the sand would be favored, as well as dark-colored mice that can hide in the grass. Medium-colored mice, on the other hand, would not blend in with either the grass or the sand, and would thus be more likely to be eaten by predators. The result of this type of selection is increased genetic variance as the population becomes more diverse. Visual Connection In recent years, factories have become cleaner, and less soot is released into the environment. What impact do you think this has had on the distribution of moth color in the population? Frequency-dependent Selection Another type of selection, called frequency-dependent selection , favors phenotypes that are either common (positive frequency-dependent selection) or rare (negative frequency-dependent selection). An interesting example of this type of selection is seen in a unique group of lizards of the Pacific Northwest. Male common side-blotched lizards come in three throat-color patterns: orange, blue, and yellow. Each of these forms has a different reproductive strategy: orange males are the strongest and can fight other males for access to their females; blue males are medium-sized and form strong pair bonds with their mates; and yellow males ( Figure 19.9 ) are the smallest, and look a bit like females, which allows them to sneak copulations. Like a game of rock-paper-scissors, orange beats blue, blue beats yellow, and yellow beats orange in the competition for females. That is, the big, strong orange males can fight off the blue males to mate with the blue’s pair-bonded females, the blue males are successful at guarding their mates against yellow sneaker males, and the yellow males can sneak copulations from the potential mates of the large, polygynous orange males. In this scenario, orange males will be favored by natural selection when the population is dominated by blue males, blue males will thrive when the population is mostly yellow males, and yellow males will be selected for when orange males are the most populous. As a result, populations of side-blotched lizards cycle in the distribution of these phenotypes—in one generation, orange might be predominant, and then yellow males will begin to rise in frequency. Once yellow males make up a majority of the population, blue males will be selected for. Finally, when blue males become common, orange males will once again be favored. Negative frequency-dependent selection serves to increase the population’s genetic variance by selecting for rare phenotypes, whereas positive frequency-dependent selection usually decreases genetic variance by selecting for common phenotypes. Sexual Selection Males and females of certain species are often quite different from one another in ways beyond the reproductive organs. Males are often larger, for example, and display many elaborate colors and adornments, like the peacock’s tail, while females tend to be smaller and duller in decoration. Such differences are known as sexual dimorphisms ( Figure 19.10 ), which arise from the fact that in many populations, particularly animal populations, there is more variance in the reproductive success of the males than there is of the females. That is, some males—often the bigger, stronger, or more decorated males—get the vast majority of the total matings, while others receive none. This can occur because the males are better at fighting off other males, or because females will choose to mate with the bigger or more decorated males. In either case, this variation in reproductive success generates a strong selection pressure among males to get those matings, resulting in the evolution of bigger body size and elaborate ornaments to get the females’ attention. Females, on the other hand, tend to get a handful of selected matings; therefore, they are more likely to select more desirable males. Sexual dimorphism varies widely among species, of course, and some species are even sex-role reversed. In such cases, females tend to have a greater variance in their reproductive success than males and are correspondingly selected for the bigger body size and elaborate traits usually characteristic of males. The selection pressures on males and females to obtain matings is known as sexual selection; it can result in the development of secondary sexual characteristics that do not benefit the individual’s likelihood of survival but help to maximize its reproductive success. Sexual selection can be so strong that it selects for traits that are actually detrimental to the individual’s survival. Think, once again, about the peacock’s tail. While it is beautiful and the male with the largest, most colorful tail is more likely to win the female, it is not the most practical appendage. In addition to being more visible to predators, it makes the males slower in their attempted escapes. There is some evidence that this risk, in fact, is why females like the big tails in the first place. The speculation is that large tails carry risk, and only the best males survive that risk: the bigger the tail, the more fit the male. This idea is known as the handicap principle . The good genes hypothesis states that males develop these impressive ornaments to show off their efficient metabolism or their ability to fight disease. Females then choose males with the most impressive traits because it signals their genetic superiority, which they will then pass on to their offspring. Though it might be argued that females should not be picky because it will likely reduce their number of offspring, if better males father more fit offspring, it may be beneficial. Fewer, healthier offspring may increase the chances of survival more than many, weaker offspring. Link to Learning In 1915, biologist Ronald Fisher proposed another model of sexual selection: the Fisherian runaway model , which suggests that selection of certain traits is a result of sexual preference. In both the handicap principle and the good genes hypothesis, the trait is said to be an honest signal of the males’ quality, thus giving females a way to find the fittest mates— males that will pass the best genes to their offspring. No Perfect Organism Natural selection is a driving force in evolution and can generate populations that are better adapted to survive and successfully reproduce in their environments. But natural selection cannot produce the perfect organism. Natural selection can only select on existing variation in the population; it does not create anything from scratch. Thus, it is limited by a population’s existing genetic variance and whatever new alleles arise through mutation and gene flow. Natural selection is also limited because it works at the level of individuals, not alleles, and some alleles are linked due to their physical proximity in the genome, making them more likely to be passed on together (linkage disequilibrium). Any given individual may carry some beneficial alleles and some unfavorable alleles. It is the net effect of these alleles, or the organism’s fitness, upon which natural selection can act. As a result, good alleles can be lost if they are carried by individuals that also have several overwhelmingly bad alleles; likewise, bad alleles can be kept if they are carried by individuals that have enough good alleles to result in an overall fitness benefit. Furthermore, natural selection can be constrained by the relationships between different polymorphisms. One morph may confer a higher fitness than another, but may not increase in frequency due to the fact that going from the less beneficial to the more beneficial trait would require going through a less beneficial phenotype. Think back to the mice that live at the beach. Some are light-colored and blend in with the sand, while others are dark and blend in with the patches of grass. The dark-colored mice may be, overall, more fit than the light-colored mice, and at first glance, one might expect the light-colored mice be selected for a darker coloration. But remember that the intermediate phenotype, a medium-colored coat, is very bad for the mice—they cannot blend in with either the sand or the grass and are more likely to be eaten by predators. As a result, the light-colored mice would not be selected for a dark coloration because those individuals that began moving in that direction (began being selected for a darker coat) would be less fit than those that stayed light. Finally, it is important to understand that not all evolution is adaptive. While natural selection selects the fittest individuals and often results in a more fit population overall, other forces of evolution, including genetic drift and gene flow, often do the opposite: introducing deleterious alleles to the population’s gene pool. Evolution has no purpose—it is not changing a population into a preconceived ideal. It is simply the sum of the various forces described in this chapter and how they influence the genetic and phenotypic variance of a population.
business_law_i_essentials
Chapter Outline 11.1 History of Antitrust Law 11.2 Antitrust Laws Introduction Learning Outcome Analyze the tenets of antitrust laws in the United States.
[ { "answer": { "ans_choice": 1, "ans_text": "b" }, "bloom": null, "hl_context": "During the late 1800s , the United States became concerned about the development of corporate monopolies dominating the manufacturing and mining industries ( Jurist , n . d . ) . The end of the Civil War marked the beginning of large advances in industrialization . Many large companies formed , especially in the oil and steel industries , which were two industries that the country was beginning to heavily rely on . Manufacturing and distributing companies grew at a fast pace in a wide variety of industries , ranging from sugar to beef to tobacco ( West , n . d . ) . The problem was that the growth occurred so rapidly that supply exceeded demand . <hl> This outcome increased competition , and many companies sought to reduce the number of competitors through forms of restraint of trade such as price-fixing , monopolies , and mergers ( West , n . d . ) . <hl>", "hl_sentences": "This outcome increased competition , and many companies sought to reduce the number of competitors through forms of restraint of trade such as price-fixing , monopolies , and mergers ( West , n . d . ) .", "question": { "cloze_format": "___ is valid defense under Title VII.", "normal_format": "Which of the following is valid defense under Title VII?", "question_choices": [ "Monopolies.", "Oversupply.", "Price-fixing.", "Mergers." ], "question_id": "fs-212325318356", "question_text": "All of the following are forms of restraint of trade that company might use to reduce competition except:" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 3, "ans_text": "The Sherman Act." }, "bloom": null, "hl_context": "<hl> The first antitrust law created was the Sherman Antitrust Act in 1890 , which became the basis for subsequent antitrust laws ( Jurist , 2013 ) . <hl> The Sherman Act was a good start , but it was not comprehensive enough to prevent trusts , and large companies continued to exert strong control over industries . At the turn of the century , a few large companies controlled almost half of all of the nation ’ s manufacturing assets ( West , n . d . ) . It became evident that more legislation was necessary . President Theodore Roosevelt dubbed himself a “ trustbuster , ” and he began a campaign to create more effective legal endeavors ( West , n . d . ) . Additional antitrust acts were passed in 1914 , including the Clayton Act and the Federal Trade Commission Act . These acts are still in effect , and since 1914 , they have been amended by Congress to continue to expand upon and solidify the coverage . It is estimated that antitrust laws save consumers millions of dollars a year , as they prohibit business practices that unfairly raise prices on goods and services ( United States Department of Justice , n . d . ) .", "hl_sentences": "The first antitrust law created was the Sherman Antitrust Act in 1890 , which became the basis for subsequent antitrust laws ( Jurist , 2013 ) .", "question": { "cloze_format": "___ was the first antitrust law enacted.", "normal_format": "What was the first antitrust law enacted?", "question_choices": [ "The Clayton Act.", "The Federal Trade Commission Act.", "The Antitrust Act.", "The Sherman Act." ], "question_id": "fs-21235318356", "question_text": "What was the first antitrust law enacted?." }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 0, "ans_text": "Temporary limited restraints." }, "bloom": null, "hl_context": "<hl> The Sherman Act was passed in 1890 and focused on trade restraints that were considered unreasonable ( Federal Trade Commission , n . d . ) . <hl> <hl> This Act did not prohibit all forms of trade restraint , since the courts did not see temporary limited restraints as an issue at the time . <hl> A partnership agreement that limited trade to certain areas for certain partners was considered acceptable . The courts deemed some trade restrictions as unreasonable , such as price fixing ( Federal Trade Commission , n . d . ) . In some cases , the violation was so apparent that the violation was considered prima facie , or so evident that it automatically satisfied the unreasonable standard ( Jurist , 2013 ) .", "hl_sentences": "The Sherman Act was passed in 1890 and focused on trade restraints that were considered unreasonable ( Federal Trade Commission , n . d . ) . This Act did not prohibit all forms of trade restraint , since the courts did not see temporary limited restraints as an issue at the time .", "question": { "cloze_format": "___ are not prohibited by the Sherman Act.", "normal_format": "Which of the following is not prohibited by the Sherman Act?", "question_choices": [ "Temporary limited restraints.", "Temporary restraints.", "Naked restraints.", "Ancillary restraints." ], "question_id": "fs-212323183560", "question_text": "Which of the following is not prohibited by the Sherman Act?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 2, "ans_text": "c" }, "bloom": null, "hl_context": "The Act is a criminal statute , meaning that violation of this Act would result in criminal penalties . Mergers or other actions that would create agreements to fix prices or bids or allocate customers are considered criminal felonies ( The United States Department of Justice , n . d . ) . <hl> Violations of the Sherman Act could lead to penalties of up to $ 100 million for larger corporations and up to $ 1 million for individuals ( Federal Trade Commission , n . d . ) . <hl> Those convicted could also face up to 10 years in prison . If the amount gained by the conspirators , or the amount lost by the victims of the crime , is over $ 100 million , the fine could be increased to twice the amount gained by the conspirators or lost by the victims — whichever is greater ( Federal Trade Commission , n . d . ) .", "hl_sentences": "Violations of the Sherman Act could lead to penalties of up to $ 100 million for larger corporations and up to $ 1 million for individuals ( Federal Trade Commission , n . d . ) .", "question": { "cloze_format": "A possible penalty for violation of the Sherman Act is ___ .", "normal_format": "Which of the following are possible penalties for violation of the Sherman Act?", "question_choices": [ "Up to $100 million for corporations and individuals.", "Up to $100 million for individuals.", "Up to $100 millions for corporations.", "None of these are correct." ], "question_id": "fs-21232383560", "question_text": "Which of the following are possible penalties for violation of the Sherman Act?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 3, "ans_text": "All of the above." }, "bloom": null, "hl_context": "<hl> Corporate mergers , which result in the acquisition of competing companies <hl> <hl> Exclusive dealing contracts , which require buyers to purchase only from one business and not competitors <hl> <hl> Price discrimination , which occurs as the same product is sold to different buyers at different prices <hl> The Clayton Act was passed in 1914 . The Clayton Act is a civil statute rather than a criminal statute , meaning that it carries civil penalties rather than prison sentences ( United States Department of Justice , n . d . ) . It primarily focuses on unfair mergers and acquisitions ( Jurist , 2013 ) . This Act sought to create more specific language to help the courts reduce unfair trade practices . <hl> As such , it established four acts as illegal , but not criminal , meaning that they would be tried as civil matters . <hl> <hl> The four acts are ( West , n . d . ): <hl>", "hl_sentences": "Corporate mergers , which result in the acquisition of competing companies Exclusive dealing contracts , which require buyers to purchase only from one business and not competitors Price discrimination , which occurs as the same product is sold to different buyers at different prices As such , it established four acts as illegal , but not criminal , meaning that they would be tried as civil matters . The four acts are ( West , n . d . ):", "question": { "cloze_format": "___ is/are considered illegal by the Clayton Act.", "normal_format": "Which of the following are considered illegal by the Clayton Act?", "question_choices": [ "Price discrimination.", "Exclusive dealing contracts.", "Corporate mergers.", "All of the above." ], "question_id": "fs-212323356", "question_text": "Which of the following are considered illegal by the Clayton Act?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 2, "ans_text": "c" }, "bloom": null, "hl_context": "<hl> Labor – A labor union can organize and bargain within the bounds of antitrust laws , as long as it does not combine with a nonlabor group . <hl> The four acts would only be considered illegal when they create monopolies or substantially lessen competition ( West , n . d . ) . <hl> Unions were excluded from mention in the Clayton Act , as Congress did not wish to treat human labor as a commodity ( West , n . d . ) . <hl> This Act was still broad enough to rely on the courts for interpretation and decisions on a case-by-case basis . <hl> The Federal Trade Commission Act <hl> <hl> The Clayton Act <hl> <hl> The Sherman Antitrust Act <hl> <hl> Antitrust laws were created to prevent unlawful mergers and business practices that could lead to restraint of trade by others ( Federal Trade Commission , n . d . ) . <hl> The laws themselves are somewhat general to allow the courts the ability to make decisions on these practices , based on changing times and markets ( Federal Trade Commission , n . d . ) . The three main antitrust laws that are in effect have been in effect for over 100 years and through many changes in society — from an industrial age to a technological age , and the changing markets they represent . <hl> The federal government created and enforces these three main antitrust laws : <hl>", "hl_sentences": "Labor – A labor union can organize and bargain within the bounds of antitrust laws , as long as it does not combine with a nonlabor group . Unions were excluded from mention in the Clayton Act , as Congress did not wish to treat human labor as a commodity ( West , n . d . ) . The Federal Trade Commission Act The Clayton Act The Sherman Antitrust Act Antitrust laws were created to prevent unlawful mergers and business practices that could lead to restraint of trade by others ( Federal Trade Commission , n . d . ) . The federal government created and enforces these three main antitrust laws :", "question": { "cloze_format": "___ are exempt from antitrust laws.", "normal_format": "Which of the following are exempt from antitrust laws?", "question_choices": [ "Small businesses.", "Coops.", "Labor unions.", "Agriculture groups even if they engage in restraint of trade." ], "question_id": "fs-21232356", "question_text": "The following are exempt from antitrust laws:" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 1, "ans_text": "1914." }, "bloom": null, "hl_context": "<hl> The Federal Trade Commission Act ( FTC Act ) , also passed in 1914 , focuses on unfair methods of competition and deceptive acts or practices that impact commerce ( West , n . d . ) . <hl> All acts that violate the Sherman Act also violate the FTC Act ( Federal Trade Commission , n . d . ) . The FTC Act works to fill in the gaps of the unfair practices by condemning all anticompetitive behaviors not otherwise covered in the other federal antitrust laws ( West , n . d . ) .", "hl_sentences": "The Federal Trade Commission Act ( FTC Act ) , also passed in 1914 , focuses on unfair methods of competition and deceptive acts or practices that impact commerce ( West , n . d . ) .", "question": { "cloze_format": "The Federal Trade Commission was established in the year ___ .", "normal_format": "When was the Federal Trade Commission established?", "question_choices": [ "1912.", "1914.", "1916.", "1920." ], "question_id": "fs-21232531356", "question_text": "When was the Federal Trade Commission established?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 0, "ans_text": "a" }, "bloom": null, "hl_context": "<hl> The three main antitrust laws , namely the Sherman Act , the Clayton Act , and the Federal Trade Commission Act , all work to prevent unfair trade practices that can substantially harm free competition . <hl> They also work to protect consumers from practices that would control pricing or the ability to buy or engage in services . They prevent companies from taking actions that would allow them to become too big or too powerful , thus controlling how , and what , consumers and other businesses can do .", "hl_sentences": "The three main antitrust laws , namely the Sherman Act , the Clayton Act , and the Federal Trade Commission Act , all work to prevent unfair trade practices that can substantially harm free competition .", "question": { "cloze_format": "The ___ is not a bureau of the Federal Trade Commission.", "normal_format": "The following are bureaus of the Federal Trade Commission except which one?", "question_choices": [ "Bureau of Unfair Trade Practices.", "Bureau of Consumer Protection.", "Bureau of Competition.", "Bureau Economics." ], "question_id": "fs-2123253356", "question_text": "The following are bureaus of the Federal Trade Commission except:" }, "references_are_paraphrase": 0 } ]
11
11.1 History of Antitrust Law What if the two largest manufacturers of soft drinks, Coca Cola Co. and PepsiCo, merged? It is likely that the mega-company that resulted would dominate the soft drink industry, squeezing out all of the other smaller competitors. In the late 1800s, concern over this kind of merger, as well as other attempts by large companies to create monopolies or to control the market, led state and federal lawmakers to take steps to reduce the risks associated with this type of practice. Business Trusts During the late 1800s, the United States became concerned about the development of corporate monopolies dominating the manufacturing and mining industries (Jurist, n.d.). The end of the Civil War marked the beginning of large advances in industrialization. Many large companies formed, especially in the oil and steel industries, which were two industries that the country was beginning to heavily rely on. Manufacturing and distributing companies grew at a fast pace in a wide variety of industries, ranging from sugar to beef to tobacco (West, n.d.). The problem was that the growth occurred so rapidly that supply exceeded demand. This outcome increased competition, and many companies sought to reduce the number of competitors through forms of restraint of trade such as price-fixing, monopolies, and mergers (West, n.d.). Some of the competitors were larger and more powerful than others, and they sought to limit the competition in the market by taking steps to reduce the number of smaller companies who were trying to compete with them (Federal Trade Commission, n.d.). Some of the larger companies banded together to create business trusts . A business trust is a trust agreement that allows businesses to maintain profits as beneficiaries, but legal ownership and management of the company’s property is maintained through the power of trustees (West, n.d.). These trusts allowed businesses that were members of the trust to grow larger, as they cooperated with one another and shut out other competitors (West, n.d.). Unfair Business Practices Companies tried to create situations that would drive some competitors out of business while solidifying their own share of the market. This effort resulted in mergers and consolidation practices that placed the largest share of the industries under the control of just a few, thereby increasing their power. Since the trusts were able to fix prices and could afford to take some losses, they would drive prices down until competitors were forced out of business because they could not afford to operate at the lower rates (West. n.d.). The markets began to consolidate under just a few companies because the smaller competitors continued to go out of business. The smaller competitors could not compete with the pricing and other practices that the trusts allowed the cooperative businesses to maintain. This design restricted free trade practices for both businesses and consumers. The few businesses in the trust, in turn, became more powerful, thus prompting the government to look for measures to control the situation (Federal Trade Commission, n.d.). The government determined that laws needed to be created to prevent this form of trade restriction. Rule of Reason Unfair business practices did not reside solely with business trusts. Issues also occurred in agreements between competitors, contracts entered into between sellers and buyers, and practices that created or maintained cartels, monopolies, and mergers (West, n.d.). There were no specific laws that regulated these practices, so the courts were not entirely sure how to deal with them. Initially, courts seemed to swing both ways, both accepting and condemning certain forms of restraint of trade. Rulings were not consistent from state to state, and guidelines needed to be established. The guiding condition seemed to be whether or not the restraints prevented other merchants from entering the market (West, n.d.). The courts used the rule of reason as the standard. The rule of reason explored the goal of the contract, which was considered either naked restraint or ancillary restraint. Naked restraint occurs as contracts promote a general restraint of competition. If the restraint was created with a goal of long-term impact without boundaries, it was considered to be a naked restraint (West, nd.). Ancillary restraint occurs as the restriction is limited in time and geography (West, n.d.). With ancillary restraint, the restraint would be short-term and limited in scope. The courts tended to frown upon naked restraint, but were less consistent with ancillary restraint. Initially, there did not seem to be a comprehensive common law applied similarly from state to state (West, n.d.). This problem was concerning enough to warrant a solution, and in 1890, the first antitrust law was enacted (Jurist, n.d.). Antitrust Laws Antitrust laws regulate economic competition in an effort to maintain fair trade practices (West, n.d.). They were created to prevent the restraints on trade created by trusts and other large company practices. These restraints often resulted in price-fixing, control of production, and control of geographical markets (Jurist, n.d.). Many states recognized these outcomes as a threat to fair business practices. The federal government also recognized this issue and developed antitrust laws in 1887 as a result of a Standard Oil trust that was formed. The Standard Oil Trust occurred as oil companies transferred their stocks to a trustee to create a more powerful block of oil companies that prevented other oil companies from effectively competing with them (West, n.d.). The first antitrust law created was the Sherman Antitrust Act in 1890, which became the basis for subsequent antitrust laws (Jurist, 2013). The Sherman Act was a good start, but it was not comprehensive enough to prevent trusts, and large companies continued to exert strong control over industries. At the turn of the century, a few large companies controlled almost half of all of the nation’s manufacturing assets (West, n.d.). It became evident that more legislation was necessary. President Theodore Roosevelt dubbed himself a “trustbuster,” and he began a campaign to create more effective legal endeavors (West, n.d.). Additional antitrust acts were passed in 1914, including the Clayton Act and the Federal Trade Commission Act. These acts are still in effect, and since 1914, they have been amended by Congress to continue to expand upon and solidify the coverage. It is estimated that antitrust laws save consumers millions of dollars a year, as they prohibit business practices that unfairly raise prices on goods and services (United States Department of Justice, n.d.). Conclusion The original purpose of antitrust legislation, i.e., to foster competition that results in lower prices, more products, and more equal distribution of wealth between producers, remains relevant today (West, n.d.). Yet, large companies still seek advantages in trade and work to put competitors out of business. It is important to maintain unrestrained trade and prevent the few from having too much power over the many. Sources Federal Trade Commission (n.d.). The antitrust laws. Retrieved from: https://www.ftc.gov/tips-advice/competition-guidance/guide-antitrust-laws/antitrust-laws. Jurist (2013). History of antitrust laws. Retrieved from: https://www.jurist.org/archives/feature/a-history-and-the-main-acts/. United States Department of Justice (n.d.). Antitrust laws and you. Retrieved from: https://www.justice.gov/atr/antitrust-laws-and-you. West’s Encyclopedia of American Law (n.d.). Antitrust law. Retrieved from: >http://iris.nyit.edu/~shartman/mba0101/trust.htm. 11.2 Antitrust Laws Antitrust legislation was designed to prevent unfair restrictions on trade and to maintain equal opportunity for trade for businesses and consumers alike. Throughout the history of antitrust laws, legislation has become more comprehensive and structured to keep up with the business practices of larger corporations that continue to seek advantages and control through trade practices. What Do Antitrust Laws Do? Antitrust laws were created to prevent unlawful mergers and business practices that could lead to restraint of trade by others (Federal Trade Commission, n.d.). The laws themselves are somewhat general to allow the courts the ability to make decisions on these practices, based on changing times and markets (Federal Trade Commission, n.d.). The three main antitrust laws that are in effect have been in effect for over 100 years and through many changes in society—from an industrial age to a technological age, and the changing markets they represent. The federal government created and enforces these three main antitrust laws: The Sherman Antitrust Act The Clayton Act The Federal Trade Commission Act Each state has its own antitrust laws that pertain to trade practices within each separate state, but federal laws are able to reach beyond the states to interstate trade. The Sherman Antitrust Act The Sherman Act was passed in 1890 and focused on trade restraints that were considered unreasonable (Federal Trade Commission, n.d.). This Act did not prohibit all forms of trade restraint, since the courts did not see temporary limited restraints as an issue at the time. A partnership agreement that limited trade to certain areas for certain partners was considered acceptable. The courts deemed some trade restrictions as unreasonable, such as price fixing (Federal Trade Commission, n.d.). In some cases, the violation was so apparent that the violation was considered prima facie , or so evident that it automatically satisfied the unreasonable standard (Jurist, 2013). The Sherman Act prohibits all contracts and interactions that unreasonably restrain foreign trade and trade between states (United States Department of Justice, n.d.). This prohibition does not mean that companies cannot lower prices on goods in an effort to outsell the competition. Doing so would be considered fair competition and trade. However, when a company is able to suppress the ability of others to compete through some intentional unfair business practice, such as forming agreements with competitors to set prices, it is considered a violation. The Act is a criminal statute, meaning that violation of this Act would result in criminal penalties. Mergers or other actions that would create agreements to fix prices or bids or allocate customers are considered criminal felonies (The United States Department of Justice, n.d.). Violations of the Sherman Act could lead to penalties of up to $100 million for larger corporations and up to $1 million for individuals (Federal Trade Commission, n.d.). Those convicted could also face up to 10 years in prison. If the amount gained by the conspirators, or the amount lost by the victims of the crime, is over $100 million, the fine could be increased to twice the amount gained by the conspirators or lost by the victims—whichever is greater (Federal Trade Commission, n.d.). The Sherman Act did have limitations. It did not provide clear and specific language, which left the courts to make decisions on a case-by-case basis, without any consistent precedent on which to rely (West, n.d.). Precedent occurs as courts make rulings in certain cases, and those rulings are followed in subsequent cases. This lack of precedent left many larger companies in control of their restraint of trade practices, and new legislation seemed necessary. The Clayton Act The Clayton Act was passed in 1914. The Clayton Act is a civil statute rather than a criminal statute, meaning that it carries civil penalties rather than prison sentences (United States Department of Justice, n.d.). It primarily focuses on unfair mergers and acquisitions (Jurist, 2013). This Act sought to create more specific language to help the courts reduce unfair trade practices. As such, it established four acts as illegal, but not criminal, meaning that they would be tried as civil matters. The four acts are (West, n.d.): Price discrimination, which occurs as the same product is sold to different buyers at different prices Exclusive dealing contracts, which require buyers to purchase only from one business and not competitors Corporate mergers, which result in the acquisition of competing companies Interlocking directorates, which are boards of competing companies with common members sitting on each of the boards The four acts would only be considered illegal when they create monopolies or substantially lessen competition (West, n.d.). Unions were excluded from mention in the Clayton Act, as Congress did not wish to treat human labor as a commodity (West, n.d.). This Act was still broad enough to rely on the courts for interpretation and decisions on a case-by-case basis. The Clayton Act was amended in 1976 to require companies planning larger mergers and acquisitions to notify the government in advance and seek authorization (Federal Trade Commission, n.d.). This amendment also provides individuals who are victims of these practices with the ability to sue for triple damages after harm is established (Federal Trade Commission, n.d.). The Federal Trade Commission Act The Federal Trade Commission Act (FTC Act), also passed in 1914, focuses on unfair methods of competition and deceptive acts or practices that impact commerce (West, n.d.). All acts that violate the Sherman Act also violate the FTC Act (Federal Trade Commission, n.d.). The FTC Act works to fill in the gaps of the unfair practices by condemning all anticompetitive behaviors not otherwise covered in the other federal antitrust laws (West, n.d.). The FTC Act is only enforceable by the Federal Trade Commission (FTC), which was created as a result of this Act (Jurist, 2013). The FTC implements the Act’s provisions, and the FTC and the U.S. Department of Justice (DOJ) are the federal agencies responsible for prosecuting violators in either civil or criminal proceedings, depending on the act violated. One remedy that the FTC or DOJ can seek is divestiture , which forces the company to give up one or more of its operating functions (West, n.d.). Another remedy is dissolution , which would terminate the right of a partnership to exist (West, n.d.). Exemptions There are limitations on antitrust laws that have been introduced over the years. These include: Labor – A labor union can organize and bargain within the bounds of antitrust laws, as long as it does not combine with a nonlabor group. Agriculture and Fisheries – Collective co-ops of agricultural groups or fisheries can form, as long as they do not engage in restraint of trade. Foreign Trade – Companies can join forces in cooperative activities involving foreign trade exports, as long as trade within the United States is not restrained. Cooperative Research and Production – Small businesses can cooperatively work together on research joint ventures. In essence, exemptions are allowed, as long as they do not act to restrain trade in the United States (West, n.d.). Once restraint of trade becomes a factor, the practices are no longer exemptions and are subject to antitrust laws. Conclusion The three main antitrust laws, namely the Sherman Act, the Clayton Act, and the Federal Trade Commission Act, all work to prevent unfair trade practices that can substantially harm free competition. They also work to protect consumers from practices that would control pricing or the ability to buy or engage in services. They prevent companies from taking actions that would allow them to become too big or too powerful, thus controlling how, and what, consumers and other businesses can do.
anatomy_and_physiology
Chapter Objectives After studying this chapter, you will be able to: Describe the components of the somatic nervous system Name the modalities and submodalities of the sensory systems Distinguish between general and special senses Describe regions of the central nervous system that contribute to somatic functions Explain the stimulus-response motor pathway Introduction The somatic nervous system is traditionally considered a division within the peripheral nervous system. However, this misses an important point: somatic refers to a functional division, whereas peripheral refers to an anatomic division. The somatic nervous system is responsible for our conscious perception of the environment and for our voluntary responses to that perception by means of skeletal muscles. Peripheral sensory neurons receive input from environmental stimuli, but the neurons that produce motor responses originate in the central nervous system. The distinction between the structures (i.e., anatomy) of the peripheral and central nervous systems and functions (i.e., physiology) of the somatic and autonomic systems can most easily be demonstrated through a simple reflex action. When you touch a hot stove, you pull your hand away. Sensory receptors in the skin sense extreme temperature and the early signs of tissue damage. This triggers an action potential, which travels along the sensory fiber from the skin, through the dorsal spinal root to the spinal cord, and directly activates a ventral horn motor neuron. That neuron sends a signal along its axon to excite the biceps brachii, causing contraction of the muscle and flexion of the forearm at the elbow to withdraw the hand from the hot stove. The withdrawal reflex has more components, such as inhibiting the opposing muscle and balancing posture while the arm is forcefully withdrawn, which will be further explored at the end of this chapter. The basic withdrawal reflex explained above includes sensory input (the painful stimulus), central processing (the synapse in the spinal cord), and motor output (activation of a ventral motor neuron that causes contraction of the biceps brachii). Expanding the explanation of the withdrawal reflex can include inhibition of the opposing muscle, or cross extension, either of which increase the complexity of the example by involving more central neurons. A collateral branch of the sensory axon would inhibit another ventral horn motor neuron so that the triceps brachii do not contract and slow the withdrawal down. The cross extensor reflex provides a counterbalancing movement on the other side of the body, which requires another collateral of the sensory axon to activate contraction of the extensor muscles in the contralateral limb. A more complex example of somatic function is conscious muscle movement. For example, reading of this text starts with visual sensory input to the retina, which then projects to the thalamus, and on to the cerebral cortex. A sequence of regions of the cerebral cortex process the visual information, starting in the primary visual cortex of the occipital lobe, and resulting in the conscious perception of these letters. Subsequent cognitive processing results in understanding of the content. As you continue reading, regions of the cerebral cortex in the frontal lobe plan how to move the eyes to follow the lines of text. The output from the cortex causes activity in motor neurons in the brain stem that cause movement of the extraocular muscles through the third, fourth, and sixth cranial nerves. This example also includes sensory input (the retinal projection to the thalamus), central processing (the thalamus and subsequent cortical activity), and motor output (activation of neurons in the brain stem that lead to coordinated contraction of extraocular muscles).
[ { "answer": { "ans_choice": 1, "ans_text": "nociceptor" }, "bloom": "1", "hl_context": "Receptor cells can be further categorized on the basis of the type of stimuli they transduce . Chemical stimuli can be interpreted by a chemoreceptor that interprets chemical stimuli , such as an object ’ s taste or smell . Osmoreceptors respond to solute concentrations of body fluids . <hl> Additionally , pain is primarily a chemical sense that interprets the presence of chemicals from tissue damage , or similar intense stimuli , through a nociceptor . <hl> Physical stimuli , such as pressure and vibration , as well as the sensation of sound and body position ( balance ) , are interpreted through a mechanoreceptor . Another physical stimulus that has its own type of receptor is temperature , which is sensed through a thermoreceptor that is either sensitive to temperatures above ( heat ) or below ( cold ) normal body temperature .", "hl_sentences": "Additionally , pain is primarily a chemical sense that interprets the presence of chemicals from tissue damage , or similar intense stimuli , through a nociceptor .", "question": { "cloze_format": "The ___ is a type of receptor cell that is responsible for transducing pain stimuli.", "normal_format": "What type of receptor cell is responsible for transducing pain stimuli?", "question_choices": [ "mechanoreceptor", "nociceptor", "osmoreceptor", "photoreceptor" ], "question_id": "fs-id2174387", "question_text": "What type of receptor cell is responsible for transducing pain stimuli?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 3, "ans_text": "facial" }, "bloom": "1", "hl_context": "<hl> Once the gustatory cells are activated by the taste molecules , they release neurotransmitters onto the dendrites of sensory neurons . <hl> <hl> These neurons are part of the facial and glossopharyngeal cranial nerves , as well as a component within the vagus nerve dedicated to the gag reflex . <hl> The facial nerve connects to taste buds in the anterior third of the tongue . The glossopharyngeal nerve connects to taste buds in the posterior two thirds of the tongue . The vagus nerve connects to taste buds in the extreme posterior of the tongue , verging on the pharynx , which are more sensitive to noxious stimuli such as bitterness .", "hl_sentences": "Once the gustatory cells are activated by the taste molecules , they release neurotransmitters onto the dendrites of sensory neurons . These neurons are part of the facial and glossopharyngeal cranial nerves , as well as a component within the vagus nerve dedicated to the gag reflex .", "question": { "cloze_format": "The cranial nerve that is part of the gustatory system is ___.", "normal_format": "Which of these cranial nerves is part of the gustatory system?", "question_choices": [ "olfactory", "trochlear", "trigeminal", "facial" ], "question_id": "fs-id2740806", "question_text": "Which of these cranial nerves is part of the gustatory system?" }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 1, "ans_text": "sour" }, "bloom": "1", "hl_context": "Sour taste is the perception of H + concentration . Just as with sodium ions in salty flavors , these hydrogen ions enter the cell and trigger depolarization . <hl> Sour flavors are , essentially , the perception of acids in our food . <hl> <hl> Increasing hydrogen ion concentrations in the saliva ( lowering saliva pH ) triggers progressively stronger graded potentials in the gustatory cells . <hl> For example , orange juice — which contains citric acid — will taste sour because it has a pH value of approximately 3 . Of course , it is often sweetened so that the sour taste is masked .", "hl_sentences": "Sour flavors are , essentially , the perception of acids in our food . Increasing hydrogen ion concentrations in the saliva ( lowering saliva pH ) triggers progressively stronger graded potentials in the gustatory cells .", "question": { "cloze_format": "___ is a submodality of taste that is sensitive to the pH of saliva.", "normal_format": "Which submodality of taste is sensitive to the pH of saliva?", "question_choices": [ "umami", "sour", "bitter", "sweet" ], "question_id": "fs-id2589425", "question_text": "Which submodality of taste is sensitive to the pH of saliva?" }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 3, "ans_text": "retinal ganglion cells" }, "bloom": "1", "hl_context": "The retina is composed of several layers and contains specialized cells for the initial processing of visual stimuli . The photoreceptors ( rods and cones ) change their membrane potential when stimulated by light energy . The change in membrane potential alters the amount of neurotransmitter that the photoreceptor cells release onto bipolar cells in the outer synaptic layer . <hl> It is the bipolar cell in the retina that connects a photoreceptor to a retinal ganglion cell ( RGC ) in the inner synaptic layer . <hl> There , amacrine cells additionally contribute to retinal processing before an action potential is produced by the RGC . <hl> The axons of RGCs , which lie at the innermost layer of the retina , collect at the optic disc and leave the eye as the optic nerve ( see Figure 14.15 ) . <hl> Because these axons pass through the retina , there are no photoreceptors at the very back of the eye , where the optic nerve begins . This creates a “ blind spot ” in the retina , and a corresponding blind spot in our visual field . Note that the photoreceptors in the retina ( rods and cones ) are located behind the axons , RGCs , bipolar cells , and retinal blood vessels . A significant amount of light is absorbed by these structures before the light reaches the photoreceptor cells . However , at the exact center of the retina is a small area known as the fovea . At the fovea , the retina lacks the supporting cells and blood vessels , and only contains photoreceptors . Therefore , visual acuity , or the sharpness of vision , is greatest at the fovea . This is because the fovea is where the least amount of incoming light is absorbed by other retinal structures ( see Figure 14.15 ) . As one moves in either direction from this central point of the retina , visual acuity drops significantly . In addition , each photoreceptor cell of the fovea is connected to a single RGC . Therefore , this RGC does not have to integrate inputs from multiple photoreceptors , which reduces the accuracy of visual transduction . Toward the edges of the retina , several photoreceptors converge on RGCs ( through the bipolar cells ) up to a ratio of 50 to 1 . The difference in visual acuity between the fovea and peripheral retina is easily evidenced by looking directly at a word in the middle of this paragraph . The visual stimulus in the middle of the field of view falls on the fovea and is in the sharpest focus . Without moving your eyes off that word , notice that words at the beginning or end of the paragraph are not in focus . The images in your peripheral vision are focused by the peripheral retina , and have vague , blurry edges and words that are not as clearly identified . As a result , a large part of the neural function of the eyes is concerned with moving the eyes and head so that important visual stimuli are centered on the fovea . Light falling on the retina causes chemical changes to pigment molecules in the photoreceptors , ultimately leading to a change in the activity of the RGCs . Photoreceptor cells have two parts , the inner segment and the outer segment ( Figure 14.16 ) . The inner segment contains the nucleus and other common organelles of a cell , whereas the outer segment is a specialized region in which photoreception takes place . There are two types of photoreceptors — rods and cones — which differ in the shape of their outer segment . The rod-shaped outer segments of the rod photoreceptor contain a stack of membrane-bound discs that contain the photosensitive pigment rhodopsin . The cone-shaped outer segments of the cone photoreceptor contain their photosensitive pigments in infoldings of the cell membrane . There are three cone photopigments , called opsins , which are each sensitive to a particular wavelength of light . The wavelength of visible light determines its color . The pigments in human eyes are specialized in perceiving three different primary colors : red , green , and blue . At the molecular level , visual stimuli cause changes in the photopigment molecule that lead to changes in membrane potential of the photoreceptor cell . A single unit of light is called a photon , which is described in physics as a packet of energy with properties of both a particle and a wave . The energy of a photon is represented by its wavelength , with each wavelength of visible light corresponding to a particular color . Visible light is electromagnetic radiation with a wavelength between 380 and 720 nm . Wavelengths of electromagnetic radiation longer than 720 nm fall into the infrared range , whereas wavelengths shorter than 380 nm fall into the ultraviolet range . Light with a wavelength of 380 nm is blue whereas light with a wavelength of 720 nm is dark red . All other colors fall between red and blue at various points along the wavelength scale . Opsin pigments are actually transmembrane proteins that contain a cofactor known as retinal . Retinal is a hydrocarbon molecule related to vitamin A . When a photon hits retinal , the long hydrocarbon chain of the molecule is biochemically altered . Specifically , photons cause some of the double-bonded carbons within the chain to switch from a cis to a trans conformation . This process is called photoisomerization . Before interacting with a photon , retinal ’ s flexible double-bonded carbons are in the cis conformation . This molecule is referred to as 11 - cis - retinal . A photon interacting with the molecule causes the flexible double-bonded carbons to change to the trans - conformation , forming all - trans - retinal , which has a straight hydrocarbon chain ( Figure 14.17 ) . The shape change of retinal in the photoreceptors initiates visual transduction in the retina . Activation of retinal and the opsin proteins result in activation of a G protein . The G protein changes the membrane potential of the photoreceptor cell , which then releases less neurotransmitter into the outer synaptic layer of the retina . Until the retinal molecule is changed back to the 11 - cis - retinal shape , the opsin cannot respond to light energy , which is called bleaching . When a large group of photopigments is bleached , the retina will send information as if opposing visual information is being perceived . After a bright flash of light , afterimages are usually seen in negative . The photoisomerization is reversed by a series of enzymatic changes so that the retinal responds to more light energy .", "hl_sentences": "It is the bipolar cell in the retina that connects a photoreceptor to a retinal ganglion cell ( RGC ) in the inner synaptic layer . The axons of RGCs , which lie at the innermost layer of the retina , collect at the optic disc and leave the eye as the optic nerve ( see Figure 14.15 ) .", "question": { "cloze_format": "The neuron from which axons in the retina make up the optic nerve are ___.", "normal_format": "Axons from which neuron in the retina make up the optic nerve?", "question_choices": [ "amacrine cells", "photoreceptors", "bipolar cells", "retinal ganglion cells" ], "question_id": "fs-id1904177", "question_text": "Axons from which neuron in the retina make up the optic nerve?" }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 2, "ans_text": "mechanoreceptor" }, "bloom": null, "hl_context": "Receptor cells can be further categorized on the basis of the type of stimuli they transduce . Chemical stimuli can be interpreted by a chemoreceptor that interprets chemical stimuli , such as an object ’ s taste or smell . Osmoreceptors respond to solute concentrations of body fluids . Additionally , pain is primarily a chemical sense that interprets the presence of chemicals from tissue damage , or similar intense stimuli , through a nociceptor . <hl> Physical stimuli , such as pressure and vibration , as well as the sensation of sound and body position ( balance ) , are interpreted through a mechanoreceptor . <hl> Another physical stimulus that has its own type of receptor is temperature , which is sensed through a thermoreceptor that is either sensitive to temperatures above ( heat ) or below ( cold ) normal body temperature .", "hl_sentences": "Physical stimuli , such as pressure and vibration , as well as the sensation of sound and body position ( balance ) , are interpreted through a mechanoreceptor .", "question": { "cloze_format": "The ___ is a type of receptor cell that is involved in the sensations of sound and balance.", "normal_format": "What type of receptor cell is involved in the sensations of sound and balance?", "question_choices": [ "photoreceptor", "chemoreceptor", "mechanoreceptor", "nociceptor" ], "question_id": "fs-id2024484", "question_text": "What type of receptor cell is involved in the sensations of sound and balance?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 2, "ans_text": "audition" }, "bloom": null, "hl_context": "<hl> The sensory pathway for audition travels along the vestibulocochlear nerve , which synapses with neurons in the cochlear nuclei of the superior medulla . <hl> Within the brain stem , input from either ear is combined to extract location information from the auditory stimuli . Whereas the initial auditory stimuli received at the cochlea strictly represent the frequency — or pitch — of the stimuli , the locations of sounds can be determined by comparing information arriving at both ears . The trigeminal pathway carries somatosensory information from the face , head , mouth , and nasal cavity . As with the previously discussed nerve tracts , the sensory pathways of the trigeminal pathway each involve three successive neurons . First , axons from the trigeminal ganglion enter the brain stem at the level of the pons . These axons project to one of three locations . The spinal trigeminal nucleus of the medulla receives information similar to that carried by spinothalamic tract , such as pain and temperature sensations . Other axons go to either the chief sensory nucleus in the pons or the mesencephalic nuclei in the midbrain . <hl> These nuclei receive information like that carried by the dorsal column system , such as touch , pressure , vibration , and proprioception . <hl> Axons from the second neuron decussate and ascend to the thalamus along the trigeminothalamic tract . In the thalamus , each axon synapses with the third neuron in its respective pathway . Axons from the third neuron then project from the thalamus to the primary somatosensory cortex of the cerebrum . The sensory pathway for gustation travels along the facial and glossopharyngeal cranial nerves , which synapse with neurons of the solitary nucleus in the brain stem . <hl> Axons from the solitary nucleus then project to the ventral posterior nucleus of the thalamus . <hl> <hl> Finally , axons from the ventral posterior nucleus project to the gustatory cortex of the cerebral cortex , where taste is processed and consciously perceived . <hl>", "hl_sentences": "The sensory pathway for audition travels along the vestibulocochlear nerve , which synapses with neurons in the cochlear nuclei of the superior medulla . These nuclei receive information like that carried by the dorsal column system , such as touch , pressure , vibration , and proprioception . Axons from the solitary nucleus then project to the ventral posterior nucleus of the thalamus . Finally , axons from the ventral posterior nucleus project to the gustatory cortex of the cerebral cortex , where taste is processed and consciously perceived .", "question": { "cloze_format": "___ is a sensory modality that does not pass through the ventral posterior thalamus.", "normal_format": "Which of these sensory modalities does not pass through the ventral posterior thalamus?", "question_choices": [ "gustatory", "proprioception", "audition", "nociception" ], "question_id": "fs-id2136699", "question_text": "Which of these sensory modalities does not pass through the ventral posterior thalamus?" }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 3, "ans_text": "cochlear nucleus" }, "bloom": "1", "hl_context": "<hl> Auditory processing continues on to a nucleus in the midbrain called the inferior colliculus . <hl> <hl> Axons from the inferior colliculus project to two locations , the thalamus and the superior colliculus . <hl> The medial geniculate nucleus of the thalamus receives the auditory information and then projects that information to the auditory cortex in the temporal lobe of the cerebral cortex . <hl> The superior colliculus receives input from the visual and somatosensory systems , as well as the ears , to initiate stimulation of the muscles that turn the head and neck toward the auditory stimulus . <hl> <hl> The sensory pathway for audition travels along the vestibulocochlear nerve , which synapses with neurons in the cochlear nuclei of the superior medulla . <hl> <hl> Within the brain stem , input from either ear is combined to extract location information from the auditory stimuli . <hl> Whereas the initial auditory stimuli received at the cochlea strictly represent the frequency — or pitch — of the stimuli , the locations of sounds can be determined by comparing information arriving at both ears .", "hl_sentences": "Auditory processing continues on to a nucleus in the midbrain called the inferior colliculus . Axons from the inferior colliculus project to two locations , the thalamus and the superior colliculus . The superior colliculus receives input from the visual and somatosensory systems , as well as the ears , to initiate stimulation of the muscles that turn the head and neck toward the auditory stimulus . The sensory pathway for audition travels along the vestibulocochlear nerve , which synapses with neurons in the cochlear nuclei of the superior medulla . Within the brain stem , input from either ear is combined to extract location information from the auditory stimuli .", "question": { "cloze_format": "The ___ is the nucleus in the medulla that is connected to the inferior colliculus.", "normal_format": "Which nucleus in the medulla is connected to the inferior colliculus?", "question_choices": [ "solitary nucleus", "vestibular nucleus", "chief sensory nucleus", "cochlear nucleus" ], "question_id": "fs-id1708310", "question_text": "Which nucleus in the medulla is connected to the inferior colliculus?" }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 0, "ans_text": "inferior right" }, "bloom": "1", "hl_context": "Likewise , the topographic relationship between the retina and the visual cortex is maintained throughout the visual pathway . The visual field is projected onto the two retinae , as described above , with sorting at the optic chiasm . The right peripheral visual field falls on the medial portion of the right retina and the lateral portion of the left retina . The right medial retina then projects across the midline through the optic chiasm . This results in the right visual field being processed in the left visual cortex . <hl> Likewise , the left visual field is processed in the right visual cortex ( see Figure 14.22 ) . <hl> Though the chiasm is helping to sort right and left visual information , superior and inferior visual information is maintained topographically in the visual pathway . <hl> Light from the superior visual field falls on the inferior retina , and light from the inferior visual field falls on the superior retina . <hl> This topography is maintained such that the superior region of the visual cortex processes the inferior visual field and vice versa . Therefore , the visual field information is inverted and reversed as it enters the visual cortex — up is down , and left is right . However , the cortex processes the visual information such that the final conscious perception of the visual field is correct . The topographic relationship is evident in that information from the foveal region of the retina is processed in the center of the primary visual cortex . Information from the peripheral regions of the retina are correspondingly processed toward the edges of the visual cortex . Similar to the exaggerations in the sensory homunculus of the somatosensory cortex , the foveal-processing area of the visual cortex is disproportionately larger than the areas processing peripheral vision .", "hl_sentences": "Likewise , the left visual field is processed in the right visual cortex ( see Figure 14.22 ) . Light from the superior visual field falls on the inferior retina , and light from the inferior visual field falls on the superior retina .", "question": { "cloze_format": "Visual stimuli in the upper-left visual field will be processed in the ___ region of the primary visual cortex.", "normal_format": "Visual stimuli in the upper-left visual field will be processed in what region of the primary visual cortex?", "question_choices": [ "inferior right", "inferior left", "superior right", "superior left" ], "question_id": "fs-id2488211", "question_text": "Visual stimuli in the upper-left visual field will be processed in what region of the primary visual cortex?" }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 1, "ans_text": "cerebellum" }, "bloom": "1", "hl_context": "Balance is coordinated through the vestibular system , the nerves of which are composed of axons from the vestibular ganglion that carries information from the utricle , saccule , and semicircular canals . The system contributes to controlling head and neck movements in response to vestibular signals . An important function of the vestibular system is coordinating eye and head movements to maintain visual attention . Most of the axons terminate in the vestibular nuclei of the medulla . <hl> Some axons project from the vestibular ganglion directly to the cerebellum , with no intervening synapse in the vestibular nuclei . <hl> The cerebellum is primarily responsible for initiating movements on the basis of equilibrium information .", "hl_sentences": "Some axons project from the vestibular ganglion directly to the cerebellum , with no intervening synapse in the vestibular nuclei .", "question": { "cloze_format": "The ___ is a direct target of the vestibular ganglion.", "normal_format": "Which of the following is a direct target of the vestibular ganglion?", "question_choices": [ "superior colliculus", "cerebellum", "thalamus", "optic chiasm" ], "question_id": "fs-id1395460", "question_text": "Which of the following is a direct target of the vestibular ganglion?" }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 3, "ans_text": "primary motor cortex" }, "bloom": "1", "hl_context": "The motor output from the cortex descends into the brain stem and to the spinal cord to control the musculature through motor neurons . Neurons located in the primary motor cortex , named Betz cells , are large cortical neurons that synapse with lower motor neurons in the brain stem or in the spinal cord . The two descending pathways travelled by the axons of Betz cells are the corticobulbar tract and the corticospinal tract , respectively . Both tracts are named for their origin in the cortex and their targets — either the brain stem ( the term “ bulbar ” refers to the brain stem as the bulb , or enlargement , at the top of the spinal cord ) or the spinal cord . These two descending pathways are responsible for the conscious or voluntary movements of skeletal muscles . <hl> Any motor command from the primary motor cortex is sent down the axons of the Betz cells to activate lower motor neurons in either the cranial motor nuclei or in the ventral horn of the spinal cord . <hl> The axons of the corticobulbar tract are ipsilateral , meaning they project from the cortex to the motor nucleus on the same side of the nervous system . Conversely , the axons of the corticospinal tract are largely contralateral , meaning that they cross the midline of the brain stem or spinal cord and synapse on the opposite side of the body . Therefore , the right motor cortex of the cerebrum controls muscles on the left side of the body , and vice versa .", "hl_sentences": "Any motor command from the primary motor cortex is sent down the axons of the Betz cells to activate lower motor neurons in either the cranial motor nuclei or in the ventral horn of the spinal cord .", "question": { "cloze_format": "The region of the frontal lobe that is responsible for initiating movement by directly connecting to cranial and spinal motor neurons is the ___.", "normal_format": "Which region of the frontal lobe is responsible for initiating movement by directly connecting to cranial and spinal motor neurons?", "question_choices": [ "prefrontal cortex", "supplemental motor area", "premotor cortex", "primary motor cortex" ], "question_id": "fs-id2297388", "question_text": "Which region of the frontal lobe is responsible for initiating movement by directly connecting to cranial and spinal motor neurons?" }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 1, "ans_text": "vestibulospinal tract" }, "bloom": "1", "hl_context": "The tectospinal tract projects from the midbrain to the spinal cord and is important for postural movements that are driven by the superior colliculus . The name of the tract comes from an alternate name for the superior colliculus , which is the tectum . The reticulospinal tract connects the reticular system , a diffuse region of gray matter in the brain stem , with the spinal cord . This tract influences trunk and proximal limb muscles related to posture and locomotion . The reticulospinal tract also contributes to muscle tone and influences autonomic functions . <hl> The vestibulospinal tract connects the brain stem nuclei of the vestibular system with the spinal cord . <hl> <hl> This allows posture , movement , and balance to be modulated on the basis of equilibrium information provided by the vestibular system . <hl>", "hl_sentences": "The vestibulospinal tract connects the brain stem nuclei of the vestibular system with the spinal cord . This allows posture , movement , and balance to be modulated on the basis of equilibrium information provided by the vestibular system .", "question": { "cloze_format": "The extrapyramidal tract that incorporates equilibrium sensations with motor commands to aid in posture and movement is the ___.", "normal_format": "Which extrapyramidal tract incorporates equilibrium sensations with motor commands to aid in posture and movement?", "question_choices": [ "tectospinal tract", "vestibulospinal tract", "reticulospinal tract", "corticospinal tract" ], "question_id": "fs-id2593232", "question_text": "Which extrapyramidal tract incorporates equilibrium sensations with motor commands to aid in posture and movement?" }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 0, "ans_text": "ventral horn" }, "bloom": "1", "hl_context": "The somatic nervous system provides output strictly to skeletal muscles . <hl> The lower motor neurons , which are responsible for the contraction of these muscles , are found in the ventral horn of the spinal cord . <hl> These large , multipolar neurons have a corona of dendrites surrounding the cell body and an axon that extends out of the ventral horn . This axon travels through the ventral nerve root to join the emerging spinal nerve . The axon is relatively long because it needs to reach muscles in the periphery of the body . The diameters of cell bodies may be on the order of hundreds of micrometers to support the long axon ; some axons are a meter in length , such as the lumbar motor neurons that innervate muscles in the first digits of the feet .", "hl_sentences": "The lower motor neurons , which are responsible for the contraction of these muscles , are found in the ventral horn of the spinal cord .", "question": { "cloze_format": "The region of gray matter in the spinal cord that contains motor neurons that innervate skeletal muscles is the ___.", "normal_format": "Which region of gray matter in the spinal cord contains motor neurons that innervate skeletal muscles?", "question_choices": [ "ventral horn", "dorsal horn", "lateral horn", "lateral column" ], "question_id": "fs-id2609107", "question_text": "Which region of gray matter in the spinal cord contains motor neurons that innervate skeletal muscles?" }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 2, "ans_text": "withdrawal reflex" }, "bloom": "1", "hl_context": "<hl> Another example of a withdrawal reflex occurs when you step on a painful stimulus , like a tack or a sharp rock . <hl> <hl> The nociceptors that are activated by the painful stimulus activate the motor neurons responsible for contraction of the tibialis anterior muscle . <hl> This causes dorsiflexion of the foot . An inhibitory interneuron , activated by a collateral branch of the nociceptor fiber , will inhibit the motor neurons of the gastrocnemius and soleus muscles to cancel plantar flexion . An important difference in this reflex is that plantar flexion is most likely in progress as the foot is pressing down onto the tack . Contraction of the tibialis anterior is not the most important aspect of the reflex , as continuation of plantar flexion will result in further damage from stepping onto the tack .", "hl_sentences": "Another example of a withdrawal reflex occurs when you step on a painful stimulus , like a tack or a sharp rock . The nociceptors that are activated by the painful stimulus activate the motor neurons responsible for contraction of the tibialis anterior muscle .", "question": { "cloze_format": "The type of reflex that can protect the foot when a painful stimulus is sensed is the ___.", "normal_format": "What type of reflex can protect the foot when a painful stimulus is sensed?", "question_choices": [ "stretch reflex", "gag reflex", "withdrawal reflex", "corneal reflex" ], "question_id": "fs-id2279372", "question_text": "What type of reflex can protect the foot when a painful stimulus is sensed?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 0, "ans_text": "homunculus" }, "bloom": "1", "hl_context": "As described earlier , many of the sensory axons are positioned in the same way as their corresponding receptor cells in the body . This allows identification of the position of a stimulus on the basis of which receptor cells are sending information . The cerebral cortex also maintains this sensory topography in the particular areas of the cortex that correspond to the position of the receptor cells . <hl> The somatosensory cortex provides an example in which , in essence , the locations of the somatosensory receptors in the body are mapped onto the somatosensory cortex . <hl> <hl> This mapping is often depicted using a sensory homunculus ( Figure 14.23 ) . <hl>", "hl_sentences": "The somatosensory cortex provides an example in which , in essence , the locations of the somatosensory receptors in the body are mapped onto the somatosensory cortex . This mapping is often depicted using a sensory homunculus ( Figure 14.23 ) .", "question": { "cloze_format": "___ is the name for the topographical representation of the sensory input to the somatosensory cortex.", "normal_format": "What is the name for the topographical representation of the sensory input to the somatosensory cortex?", "question_choices": [ "homunculus", "homo sapiens", "postcentral gyrus", "primary cortex" ], "question_id": "fs-id1406518", "question_text": "What is the name for the topographical representation of the sensory input to the somatosensory cortex?" }, "references_are_paraphrase": null } ]
14
14.1 Sensory Perception Learning Objectives By the end of this section, you will be able to: Describe different types of sensory receptors Describe the structures responsible for the special senses of taste, smell, hearing, balance, and vision Distinguish how different tastes are transduced Describe the means of mechanoreception for hearing and balance List the supporting structures around the eye and describe the structure of the eyeball Describe the processes of phototransduction A major role of sensory receptors is to help us learn about the environment around us, or about the state of our internal environment. Stimuli from varying sources, and of different types, are received and changed into the electrochemical signals of the nervous system. This occurs when a stimulus changes the cell membrane potential of a sensory neuron. The stimulus causes the sensory cell to produce an action potential that is relayed into the central nervous system (CNS), where it is integrated with other sensory information—or sometimes higher cognitive functions—to become a conscious perception of that stimulus. The central integration may then lead to a motor response. Describing sensory function with the term sensation or perception is a deliberate distinction. Sensation is the activation of sensory receptor cells at the level of the stimulus. Perception is the central processing of sensory stimuli into a meaningful pattern. Perception is dependent on sensation, but not all sensations are perceived. Receptors are the cells or structures that detect sensations. A receptor cell is changed directly by a stimulus. A transmembrane protein receptor is a protein in the cell membrane that mediates a physiological change in a neuron, most often through the opening of ion channels or changes in the cell signaling processes. Transmembrane receptors are activated by chemicals called ligands. For example, a molecule in food can serve as a ligand for taste receptors. Other transmembrane proteins, which are not accurately called receptors, are sensitive to mechanical or thermal changes. Physical changes in these proteins increase ion flow across the membrane, and can generate an action potential or a graded potential in the sensory neurons. Sensory Receptors Stimuli in the environment activate specialized receptor cells in the peripheral nervous system. Different types of stimuli are sensed by different types of receptor cells. Receptor cells can be classified into types on the basis of three different criteria: cell type, position, and function. Receptors can be classified structurally on the basis of cell type and their position in relation to stimuli they sense. They can also be classified functionally on the basis of the transduction of stimuli, or how the mechanical stimulus, light, or chemical changed the cell membrane potential. Structural Receptor Types The cells that interpret information about the environment can be either (1) a neuron that has a free nerve ending , with dendrites embedded in tissue that would receive a sensation; (2) a neuron that has an encapsulated ending in which the sensory nerve endings are encapsulated in connective tissue that enhances their sensitivity; or (3) a specialized receptor cell , which has distinct structural components that interpret a specific type of stimulus ( Figure 14.2 ). The pain and temperature receptors in the dermis of the skin are examples of neurons that have free nerve endings. Also located in the dermis of the skin are lamellated corpuscles, neurons with encapsulated nerve endings that respond to pressure and touch. The cells in the retina that respond to light stimuli are an example of a specialized receptor, a photoreceptor . Another way that receptors can be classified is based on their location relative to the stimuli. An exteroceptor is a receptor that is located near a stimulus in the external environment, such as the somatosensory receptors that are located in the skin. An interoceptor is one that interprets stimuli from internal organs and tissues, such as the receptors that sense the increase in blood pressure in the aorta or carotid sinus. Finally, a proprioceptor is a receptor located near a moving part of the body, such as a muscle, that interprets the positions of the tissues as they move. Functional Receptor Types A third classification of receptors is by how the receptor transduces stimuli into membrane potential changes. Stimuli are of three general types. Some stimuli are ions and macromolecules that affect transmembrane receptor proteins when these chemicals diffuse across the cell membrane. Some stimuli are physical variations in the environment that affect receptor cell membrane potentials. Other stimuli include the electromagnetic radiation from visible light. For humans, the only electromagnetic energy that is perceived by our eyes is visible light. Some other organisms have receptors that humans lack, such as the heat sensors of snakes, the ultraviolet light sensors of bees, or magnetic receptors in migratory birds. Receptor cells can be further categorized on the basis of the type of stimuli they transduce. Chemical stimuli can be interpreted by a chemoreceptor that interprets chemical stimuli, such as an object’s taste or smell. Osmoreceptors respond to solute concentrations of body fluids. Additionally, pain is primarily a chemical sense that interprets the presence of chemicals from tissue damage, or similar intense stimuli, through a nociceptor . Physical stimuli, such as pressure and vibration, as well as the sensation of sound and body position (balance), are interpreted through a mechanoreceptor . Another physical stimulus that has its own type of receptor is temperature, which is sensed through a thermoreceptor that is either sensitive to temperatures above (heat) or below (cold) normal body temperature. Sensory Modalities Ask anyone what the senses are, and they are likely to list the five major senses—taste, smell, touch, hearing, and sight. However, these are not all of the senses. The most obvious omission from this list is balance. Also, what is referred to simply as touch can be further subdivided into pressure, vibration, stretch, and hair-follicle position, on the basis of the type of mechanoreceptors that perceive these touch sensations. Other overlooked senses include temperature perception by thermoreceptors and pain perception by nociceptors. Within the realm of physiology, senses can be classified as either general or specific. A general sense is one that is distributed throughout the body and has receptor cells within the structures of other organs. Mechanoreceptors in the skin, muscles, or the walls of blood vessels are examples of this type. General senses often contribute to the sense of touch, as described above, or to proprioception (body movement) and kinesthesia (body movement), or to a visceral sense , which is most important to autonomic functions. A special sense is one that has a specific organ devoted to it, namely the eye, inner ear, tongue, or nose. Each of the senses is referred to as a sensory modality . Modality refers to the way that information is encoded, which is similar to the idea of transduction. The main sensory modalities can be described on the basis of how each is transduced. The chemical senses are taste and smell. The general sense that is usually referred to as touch includes chemical sensation in the form of nociception, or pain. Pressure, vibration, muscle stretch, and the movement of hair by an external stimulus, are all sensed by mechanoreceptors. Hearing and balance are also sensed by mechanoreceptors. Finally, vision involves the activation of photoreceptors. Listing all the different sensory modalities, which can number as many as 17, involves separating the five major senses into more specific categories, or submodalities , of the larger sense. An individual sensory modality represents the sensation of a specific type of stimulus. For example, the general sense of touch, which is known as somatosensation , can be separated into light pressure, deep pressure, vibration, itch, pain, temperature, or hair movement. Gustation (Taste) Only a few recognized submodalities exist within the sense of taste, or gustation . Until recently, only four tastes were recognized: sweet, salty, sour, and bitter. Research at the turn of the 20th century led to recognition of the fifth taste, umami, during the mid-1980s. Umami is a Japanese word that means “delicious taste,” and is often translated to mean savory. Very recent research has suggested that there may also be a sixth taste for fats, or lipids. Gustation is the special sense associated with the tongue. The surface of the tongue, along with the rest of the oral cavity, is lined by a stratified squamous epithelium. Raised bumps called papillae (singular = papilla) contain the structures for gustatory transduction. There are four types of papillae, based on their appearance ( Figure 14.3 ): circumvallate, foliate, filiform, and fungiform. Within the structure of the papillae are taste buds that contain specialized gustatory receptor cells for the transduction of taste stimuli. These receptor cells are sensitive to the chemicals contained within foods that are ingested, and they release neurotransmitters based on the amount of the chemical in the food. Neurotransmitters from the gustatory cells can activate sensory neurons in the facial, glossopharyngeal, and vagus cranial nerves. Salty taste is simply the perception of sodium ions (Na + ) in the saliva. When you eat something salty, the salt crystals dissociate into the component ions Na + and Cl – , which dissolve into the saliva in your mouth. The Na + concentration becomes high outside the gustatory cells, creating a strong concentration gradient that drives the diffusion of the ion into the cells. The entry of Na + into these cells results in the depolarization of the cell membrane and the generation of a receptor potential. Sour taste is the perception of H + concentration. Just as with sodium ions in salty flavors, these hydrogen ions enter the cell and trigger depolarization. Sour flavors are, essentially, the perception of acids in our food. Increasing hydrogen ion concentrations in the saliva (lowering saliva pH) triggers progressively stronger graded potentials in the gustatory cells. For example, orange juice—which contains citric acid—will taste sour because it has a pH value of approximately 3. Of course, it is often sweetened so that the sour taste is masked. The first two tastes (salty and sour) are triggered by the cations Na + and H + . The other tastes result from food molecules binding to a G protein–coupled receptor. A G protein signal transduction system ultimately leads to depolarization of the gustatory cell. The sweet taste is the sensitivity of gustatory cells to the presence of glucose dissolved in the saliva. Other monosaccharides such as fructose, or artificial sweeteners such as aspartame (NutraSweet™), saccharine, or sucralose (Splenda™) also activate the sweet receptors. The affinity for each of these molecules varies, and some will taste sweeter than glucose because they bind to the G protein–coupled receptor differently. Bitter taste is similar to sweet in that food molecules bind to G protein–coupled receptors. However, there are a number of different ways in which this can happen because there are a large diversity of bitter-tasting molecules. Some bitter molecules depolarize gustatory cells, whereas others hyperpolarize gustatory cells. Likewise, some bitter molecules increase G protein activation within the gustatory cells, whereas other bitter molecules decrease G protein activation. The specific response depends on which molecule is binding to the receptor. One major group of bitter-tasting molecules are alkaloids. Alkaloids are nitrogen containing molecules that are commonly found in bitter-tasting plant products, such as coffee, hops (in beer), tannins (in wine), tea, and aspirin. By containing toxic alkaloids, the plant is less susceptible to microbe infection and less attractive to herbivores. Therefore, the function of bitter taste may primarily be related to stimulating the gag reflex to avoid ingesting poisons. Because of this, many bitter foods that are normally ingested are often combined with a sweet component to make them more palatable (cream and sugar in coffee, for example). The highest concentration of bitter receptors appear to be in the posterior tongue, where a gag reflex could still spit out poisonous food. The taste known as umami is often referred to as the savory taste. Like sweet and bitter, it is based on the activation of G protein–coupled receptors by a specific molecule. The molecule that activates this receptor is the amino acid L-glutamate. Therefore, the umami flavor is often perceived while eating protein-rich foods. Not surprisingly, dishes that contain meat are often described as savory. Once the gustatory cells are activated by the taste molecules, they release neurotransmitters onto the dendrites of sensory neurons. These neurons are part of the facial and glossopharyngeal cranial nerves, as well as a component within the vagus nerve dedicated to the gag reflex. The facial nerve connects to taste buds in the anterior third of the tongue. The glossopharyngeal nerve connects to taste buds in the posterior two thirds of the tongue. The vagus nerve connects to taste buds in the extreme posterior of the tongue, verging on the pharynx, which are more sensitive to noxious stimuli such as bitterness. Interactive Link Watch this video to learn about Dr. Danielle Reed of the Monell Chemical Senses Center in Philadelphia, Pennsylvania, who became interested in science at an early age because of her sensory experiences. She recognized that her sense of taste was unique compared with other people she knew. Now, she studies the genetic differences between people and their sensitivities to taste stimuli. In the video, there is a brief image of a person sticking out their tongue, which has been covered with a colored dye. This is how Dr. Reed is able to visualize and count papillae on the surface of the tongue. People fall into two groups known as “tasters” and “non-tasters” based on the density of papillae on their tongue, which also indicates the number of taste buds. Non-tasters can taste food, but they are not as sensitive to certain tastes, such as bitterness. Dr. Reed discovered that she is a non-taster, which explains why she perceived bitterness differently than other people she knew. Are you very sensitive to tastes? Can you see any similarities among the members of your family? Olfaction (Smell) Like taste, the sense of smell, or olfaction , is also responsive to chemical stimuli. The olfactory receptor neurons are located in a small region within the superior nasal cavity ( Figure 14.4 ). This region is referred to as the olfactory epithelium and contains bipolar sensory neurons. Each olfactory sensory neuron has dendrites that extend from the apical surface of the epithelium into the mucus lining the cavity. As airborne molecules are inhaled through the nose, they pass over the olfactory epithelial region and dissolve into the mucus. These odorant molecules bind to proteins that keep them dissolved in the mucus and help transport them to the olfactory dendrites. The odorant–protein complex binds to a receptor protein within the cell membrane of an olfactory dendrite. These receptors are G protein–coupled, and will produce a graded membrane potential in the olfactory neurons. The axon of an olfactory neuron extends from the basal surface of the epithelium, through an olfactory foramen in the cribriform plate of the ethmoid bone, and into the brain. The group of axons called the olfactory tract connect to the olfactory bulb on the ventral surface of the frontal lobe. From there, the axons split to travel to several brain regions. Some travel to the cerebrum, specifically to the primary olfactory cortex that is located in the inferior and medial areas of the temporal lobe. Others project to structures within the limbic system and hypothalamus, where smells become associated with long-term memory and emotional responses. This is how certain smells trigger emotional memories, such as the smell of food associated with one’s birthplace. Smell is the one sensory modality that does not synapse in the thalamus before connecting to the cerebral cortex. This intimate connection between the olfactory system and the cerebral cortex is one reason why smell can be a potent trigger of memories and emotion. The nasal epithelium, including the olfactory cells, can be harmed by airborne toxic chemicals. Therefore, the olfactory neurons are regularly replaced within the nasal epithelium, after which the axons of the new neurons must find their appropriate connections in the olfactory bulb. These new axons grow along the axons that are already in place in the cranial nerve. Disorders of the... Olfactory System: Anosmia Blunt force trauma to the face, such as that common in many car accidents, can lead to the loss of the olfactory nerve, and subsequently, loss of the sense of smell. This condition is known as anosmia . When the frontal lobe of the brain moves relative to the ethmoid bone, the olfactory tract axons may be sheared apart. Professional fighters often experience anosmia because of repeated trauma to face and head. In addition, certain pharmaceuticals, such as antibiotics, can cause anosmia by killing all the olfactory neurons at once. If no axons are in place within the olfactory nerve, then the axons from newly formed olfactory neurons have no guide to lead them to their connections within the olfactory bulb. There are temporary causes of anosmia, as well, such as those caused by inflammatory responses related to respiratory infections or allergies. Loss of the sense of smell can result in food tasting bland. A person with an impaired sense of smell may require additional spice and seasoning levels for food to be tasted. Anosmia may also be related to some presentations of mild depression, because the loss of enjoyment of food may lead to a general sense of despair. The ability of olfactory neurons to replace themselves decreases with age, leading to age-related anosmia. This explains why some elderly people salt their food more than younger people do. However, this increased sodium intake can increase blood volume and blood pressure, increasing the risk of cardiovascular diseases in the elderly. Audition (Hearing) Hearing, or audition , is the transduction of sound waves into a neural signal that is made possible by the structures of the ear ( Figure 14.5 ). The large, fleshy structure on the lateral aspect of the head is known as the auricle . Some sources will also refer to this structure as the pinna, though that term is more appropriate for a structure that can be moved, such as the external ear of a cat. The C-shaped curves of the auricle direct sound waves toward the auditory canal. The canal enters the skull through the external auditory meatus of the temporal bone. At the end of the auditory canal is the tympanic membrane , or ear drum, which vibrates after it is struck by sound waves. The auricle, ear canal, and tympanic membrane are often referred to as the external ear . The middle ear consists of a space spanned by three small bones called the ossicles . The three ossicles are the malleus , incus , and stapes , which are Latin names that roughly translate to hammer, anvil, and stirrup. The malleus is attached to the tympanic membrane and articulates with the incus. The incus, in turn, articulates with the stapes. The stapes is then attached to the inner ear , where the sound waves will be transduced into a neural signal. The middle ear is connected to the pharynx through the Eustachian tube, which helps equilibrate air pressure across the tympanic membrane. The tube is normally closed but will pop open when the muscles of the pharynx contract during swallowing or yawning. The inner ear is often described as a bony labyrinth, as it is composed of a series of canals embedded within the temporal bone. It has two separate regions, the cochlea and the vestibule , which are responsible for hearing and balance, respectively. The neural signals from these two regions are relayed to the brain stem through separate fiber bundles. However, these two distinct bundles travel together from the inner ear to the brain stem as the vestibulocochlear nerve. Sound is transduced into neural signals within the cochlear region of the inner ear, which contains the sensory neurons of the spiral ganglia . These ganglia are located within the spiral-shaped cochlea of the inner ear. The cochlea is attached to the stapes through the oval window . The oval window is located at the beginning of a fluid-filled tube within the cochlea called the scala vestibuli . The scala vestibuli extends from the oval window, travelling above the cochlear duct , which is the central cavity of the cochlea that contains the sound-transducing neurons. At the uppermost tip of the cochlea, the scala vestibuli curves over the top of the cochlear duct. The fluid-filled tube, now called the scala tympani , returns to the base of the cochlea, this time travelling under the cochlear duct. The scala tympani ends at the round window , which is covered by a membrane that contains the fluid within the scala. As vibrations of the ossicles travel through the oval window, the fluid of the scala vestibuli and scala tympani moves in a wave-like motion. The frequency of the fluid waves match the frequencies of the sound waves ( Figure 14.6 ). The membrane covering the round window will bulge out or pucker in with the movement of the fluid within the scala tympani. A cross-sectional view of the cochlea shows that the scala vestibuli and scala tympani run along both sides of the cochlear duct ( Figure 14.7 ). The cochlear duct contains several organs of Corti , which transduce the wave motion of the two scala into neural signals. The organs of Corti lie on top of the basilar membrane , which is the side of the cochlear duct located between the organs of Corti and the scala tympani. As the fluid waves move through the scala vestibuli and scala tympani, the basilar membrane moves at a specific spot, depending on the frequency of the waves. Higher frequency waves move the region of the basilar membrane that is close to the base of the cochlea. Lower frequency waves move the region of the basilar membrane that is near the tip of the cochlea. The organs of Corti contain hair cells , which are named for the hair-like stereocilia extending from the cell’s apical surfaces ( Figure 14.8 ). The stereocilia are an array of microvilli-like structures arranged from tallest to shortest. Protein fibers tether adjacent hairs together within each array, such that the array will bend in response to movements of the basilar membrane. The stereocilia extend up from the hair cells to the overlying tectorial membrane , which is attached medially to the organ of Corti. When the pressure waves from the scala move the basilar membrane, the tectorial membrane slides across the stereocilia. This bends the stereocilia either toward or away from the tallest member of each array. When the stereocilia bend toward the tallest member of their array, tension in the protein tethers opens ion channels in the hair cell membrane. This will depolarize the hair cell membrane, triggering nerve impulses that travel down the afferent nerve fibers attached to the hair cells. When the stereocilia bend toward the shortest member of their array, the tension on the tethers slackens and the ion channels close. When no sound is present, and the stereocilia are standing straight, a small amount of tension still exists on the tethers, keeping the membrane potential of the hair cell slightly depolarized. Interactive Link View the University of Michigan WebScope to explore the tissue sample in greater detail. The basilar membrane is the thin membrane that extends from the central core of the cochlea to the edge. What is anchored to this membrane so that they can be activated by movement of the fluids within the cochlea? As stated above, a given region of the basilar membrane will only move if the incoming sound is at a specific frequency. Because the tectorial membrane only moves where the basilar membrane moves, the hair cells in this region will also only respond to sounds of this specific frequency. Therefore, as the frequency of a sound changes, different hair cells are activated all along the basilar membrane. The cochlea encodes auditory stimuli for frequencies between 20 and 20,000 Hz, which is the range of sound that human ears can detect. The unit of Hertz measures the frequency of sound waves in terms of cycles produced per second. Frequencies as low as 20 Hz are detected by hair cells at the apex, or tip, of the cochlea. Frequencies in the higher ranges of 20 KHz are encoded by hair cells at the base of the cochlea, close to the round and oval windows ( Figure 14.10 ). Most auditory stimuli contain a mixture of sounds at a variety of frequencies and intensities (represented by the amplitude of the sound wave). The hair cells along the length of the cochlear duct, which are each sensitive to a particular frequency, allow the cochlea to separate auditory stimuli by frequency, just as a prism separates visible light into its component colors. Interactive Link Watch this video to learn more about how the structures of the ear convert sound waves into a neural signal by moving the “hairs,” or stereocilia, of the cochlear duct. Specific locations along the length of the duct encode specific frequencies, or pitches. The brain interprets the meaning of the sounds we hear as music, speech, noise, etc. Which ear structures are responsible for the amplification and transfer of sound from the external ear to the inner ear? Interactive Link Watch this animation to learn more about the inner ear and to see the cochlea unroll, with the base at the back of the image and the apex at the front. Specific wavelengths of sound cause specific regions of the basilar membrane to vibrate, much like the keys of a piano produce sound at different frequencies. Based on the animation, where do frequencies—from high to low pitches—cause activity in the hair cells within the cochlear duct? Equilibrium (Balance) Along with audition, the inner ear is responsible for encoding information about equilibrium , the sense of balance. A similar mechanoreceptor—a hair cell with stereocilia—senses head position, head movement, and whether our bodies are in motion. These cells are located within the vestibule of the inner ear. Head position is sensed by the utricle and saccule , whereas head movement is sensed by the semicircular canals . The neural signals generated in the vestibular ganglion are transmitted through the vestibulocochlear nerve to the brain stem and cerebellum. The utricle and saccule are both largely composed of macula tissue (plural = maculae). The macula is composed of hair cells surrounded by support cells. The stereocilia of the hair cells extend into a viscous gel called the otolithic membrane ( Figure 14.11 ). On top of the otolithic membrane is a layer of calcium carbonate crystals, called otoliths. The otoliths essentially make the otolithic membrane top-heavy. The otolithic membrane moves separately from the macula in response to head movements. Tilting the head causes the otolithic membrane to slide over the macula in the direction of gravity. The moving otolithic membrane, in turn, bends the sterocilia, causing some hair cells to depolarize as others hyperpolarize. The exact position of the head is interpreted by the brain based on the pattern of hair-cell depolarization. The semicircular canals are three ring-like extensions of the vestibule. One is oriented in the horizontal plane, whereas the other two are oriented in the vertical plane. The anterior and posterior vertical canals are oriented at approximately 45 degrees relative to the sagittal plane ( Figure 14.12 ). The base of each semicircular canal, where it meets with the vestibule, connects to an enlarged region known as the ampulla . The ampulla contains the hair cells that respond to rotational movement, such as turning the head while saying “no.” The stereocilia of these hair cells extend into the cupula , a membrane that attaches to the top of the ampulla. As the head rotates in a plane parallel to the semicircular canal, the fluid lags, deflecting the cupula in the direction opposite to the head movement. The semicircular canals contain several ampullae, with some oriented horizontally and others oriented vertically. By comparing the relative movements of both the horizontal and vertical ampullae, the vestibular system can detect the direction of most head movements within three-dimensional (3-D) space. Somatosensation (Touch) Somatosensation is considered a general sense, as opposed to the special senses discussed in this section. Somatosensation is the group of sensory modalities that are associated with touch, proprioception, and interoception. These modalities include pressure, vibration, light touch, tickle, itch, temperature, pain, proprioception, and kinesthesia. This means that its receptors are not associated with a specialized organ, but are instead spread throughout the body in a variety of organs. Many of the somatosensory receptors are located in the skin, but receptors are also found in muscles, tendons, joint capsules, ligaments, and in the walls of visceral organs. Two types of somatosensory signals that are transduced by free nerve endings are pain and temperature. These two modalities use thermoreceptors and nociceptors to transduce temperature and pain stimuli, respectively. Temperature receptors are stimulated when local temperatures differ from body temperature. Some thermoreceptors are sensitive to just cold and others to just heat. Nociception is the sensation of potentially damaging stimuli. Mechanical, chemical, or thermal stimuli beyond a set threshold will elicit painful sensations. Stressed or damaged tissues release chemicals that activate receptor proteins in the nociceptors. For example, the sensation of heat associated with spicy foods involves capsaicin , the active molecule in hot peppers. Capsaicin molecules bind to a transmembrane ion channel in nociceptors that is sensitive to temperatures above 37°C. The dynamics of capsaicin binding with this transmembrane ion channel is unusual in that the molecule remains bound for a long time. Because of this, it will decrease the ability of other stimuli to elicit pain sensations through the activated nociceptor. For this reason, capsaicin can be used as a topical analgesic, such as in products such as Icy Hot™. If you drag your finger across a textured surface, the skin of your finger will vibrate. Such low frequency vibrations are sensed by mechanoreceptors called Merkel cells, also known as type I cutaneous mechanoreceptors. Merkel cells are located in the stratum basale of the epidermis. Deep pressure and vibration is transduced by lamellated (Pacinian) corpuscles, which are receptors with encapsulated endings found deep in the dermis, or subcutaneous tissue. Light touch is transduced by the encapsulated endings known as tactile (Meissner) corpuscles. Follicles are also wrapped in a plexus of nerve endings known as the hair follicle plexus. These nerve endings detect the movement of hair at the surface of the skin, such as when an insect may be walking along the skin. Stretching of the skin is transduced by stretch receptors known as bulbous corpuscles. Bulbous corpuscles are also known as Ruffini corpuscles, or type II cutaneous mechanoreceptors. Other somatosensory receptors are found in the joints and muscles. Stretch receptors monitor the stretching of tendons, muscles, and the components of joints. For example, have you ever stretched your muscles before or after exercise and noticed that you can only stretch so far before your muscles spasm back to a less stretched state? This spasm is a reflex that is initiated by stretch receptors to avoid muscle tearing. Such stretch receptors can also prevent over-contraction of a muscle. In skeletal muscle tissue, these stretch receptors are called muscle spindles. Golgi tendon organs similarly transduce the stretch levels of tendons. Bulbous corpuscles are also present in joint capsules, where they measure stretch in the components of the skeletal system within the joint. The types of nerve endings, their locations, and the stimuli they transduce are presented in Table 14.1 . Mechanoreceptors of Somatosensation Name Historical (eponymous) name Location(s) Stimuli Free nerve endings * Dermis, cornea, tongue, joint capsules, visceral organs Pain, temperature, mechanical deformation Mechanoreceptors Merkel’s discs Epidermal–dermal junction, mucosal membranes Low frequency vibration (5–15 Hz) Bulbous corpuscle Ruffini’s corpuscle Dermis, joint capsules Stretch Tactile corpuscle Meissner’s corpuscle Papillary dermis, especially in the fingertips and lips Light touch, vibrations below 50 Hz Lamellated corpuscle Pacinian corpuscle Deep dermis, subcutaneous tissue Deep pressure, high-frequency vibration (around 250 Hz) Hair follicle plexus * Wrapped around hair follicles in the dermis Movement of hair Muscle spindle * In line with skeletal muscle fibers Muscle contraction and stretch Tendon stretch organ Golgi tendon organ In line with tendons Stretch of tendons Table 14.1 *No corresponding eponymous name. Vision Vision is the special sense of sight that is based on the transduction of light stimuli received through the eyes. The eyes are located within either orbit in the skull. The bony orbits surround the eyeballs, protecting them and anchoring the soft tissues of the eye ( Figure 14.13 ). The eyelids, with lashes at their leading edges, help to protect the eye from abrasions by blocking particles that may land on the surface of the eye. The inner surface of each lid is a thin membrane known as the palpebral conjunctiva . The conjunctiva extends over the white areas of the eye (the sclera), connecting the eyelids to the eyeball. Tears are produced by the lacrimal gland , located beneath the lateral edges of the nose. Tears produced by this gland flow through the lacrimal duct to the medial corner of the eye, where the tears flow over the conjunctiva, washing away foreign particles. Movement of the eye within the orbit is accomplished by the contraction of six extraocular muscles that originate from the bones of the orbit and insert into the surface of the eyeball ( Figure 14.14 ). Four of the muscles are arranged at the cardinal points around the eye and are named for those locations. They are the superior rectus , medial rectus , inferior rectus , and lateral rectus . When each of these muscles contract, the eye moves toward the contracting muscle. For example, when the superior rectus contracts, the eye rotates to look up. The superior oblique originates at the posterior orbit, near the origin of the four rectus muscles. However, the tendon of the oblique muscles threads through a pulley-like piece of cartilage known as the trochlea . The tendon inserts obliquely into the superior surface of the eye. The angle of the tendon through the trochlea means that contraction of the superior oblique rotates the eye laterally. The inferior oblique muscle originates from the floor of the orbit and inserts into the inferolateral surface of the eye. When it contracts, it laterally rotates the eye, in opposition to the superior oblique. Rotation of the eye by the two oblique muscles is necessary because the eye is not perfectly aligned on the sagittal plane. When the eye looks up or down, the eye must also rotate slightly to compensate for the superior rectus pulling at approximately a 20-degree angle, rather than straight up. The same is true for the inferior rectus, which is compensated by contraction of the inferior oblique. A seventh muscle in the orbit is the levator palpebrae superioris , which is responsible for elevating and retracting the upper eyelid, a movement that usually occurs in concert with elevation of the eye by the superior rectus (see Figure 14.13 ). The extraocular muscles are innervated by three cranial nerves. The lateral rectus, which causes abduction of the eye, is innervated by the abducens nerve. The superior oblique is innervated by the trochlear nerve. All of the other muscles are innervated by the oculomotor nerve, as is the levator palpebrae superioris. The motor nuclei of these cranial nerves connect to the brain stem, which coordinates eye movements. The eye itself is a hollow sphere composed of three layers of tissue. The outermost layer is the fibrous tunic , which includes the white sclera and clear cornea . The sclera accounts for five sixths of the surface of the eye, most of which is not visible, though humans are unique compared with many other species in having so much of the “white of the eye” visible ( Figure 14.15 ). The transparent cornea covers the anterior tip of the eye and allows light to enter the eye. The middle layer of the eye is the vascular tunic , which is mostly composed of the choroid, ciliary body, and iris. The choroid is a layer of highly vascularized connective tissue that provides a blood supply to the eyeball. The choroid is posterior to the ciliary body , a muscular structure that is attached to the lens by suspensory ligaments, or zonule fibers . These two structures bend the lens, allowing it to focus light on the back of the eye. Overlaying the ciliary body, and visible in the anterior eye, is the iris —the colored part of the eye. The iris is a smooth muscle that opens or closes the pupil , which is the hole at the center of the eye that allows light to enter. The iris constricts the pupil in response to bright light and dilates the pupil in response to dim light. The innermost layer of the eye is the neural tunic , or retina , which contains the nervous tissue responsible for photoreception. The eye is also divided into two cavities: the anterior cavity and the posterior cavity. The anterior cavity is the space between the cornea and lens, including the iris and ciliary body. It is filled with a watery fluid called the aqueous humor . The posterior cavity is the space behind the lens that extends to the posterior side of the interior eyeball, where the retina is located. The posterior cavity is filled with a more viscous fluid called the vitreous humor . The retina is composed of several layers and contains specialized cells for the initial processing of visual stimuli. The photoreceptors (rods and cones) change their membrane potential when stimulated by light energy. The change in membrane potential alters the amount of neurotransmitter that the photoreceptor cells release onto bipolar cells in the outer synaptic layer . It is the bipolar cell in the retina that connects a photoreceptor to a retinal ganglion cell (RGC) in the inner synaptic layer . There, amacrine cells additionally contribute to retinal processing before an action potential is produced by the RGC. The axons of RGCs, which lie at the innermost layer of the retina, collect at the optic disc and leave the eye as the optic nerve (see Figure 14.15 ). Because these axons pass through the retina, there are no photoreceptors at the very back of the eye, where the optic nerve begins. This creates a “blind spot” in the retina, and a corresponding blind spot in our visual field. Note that the photoreceptors in the retina (rods and cones) are located behind the axons, RGCs, bipolar cells, and retinal blood vessels. A significant amount of light is absorbed by these structures before the light reaches the photoreceptor cells. However, at the exact center of the retina is a small area known as the fovea . At the fovea, the retina lacks the supporting cells and blood vessels, and only contains photoreceptors. Therefore, visual acuity , or the sharpness of vision, is greatest at the fovea. This is because the fovea is where the least amount of incoming light is absorbed by other retinal structures (see Figure 14.15 ). As one moves in either direction from this central point of the retina, visual acuity drops significantly. In addition, each photoreceptor cell of the fovea is connected to a single RGC. Therefore, this RGC does not have to integrate inputs from multiple photoreceptors, which reduces the accuracy of visual transduction. Toward the edges of the retina, several photoreceptors converge on RGCs (through the bipolar cells) up to a ratio of 50 to 1. The difference in visual acuity between the fovea and peripheral retina is easily evidenced by looking directly at a word in the middle of this paragraph. The visual stimulus in the middle of the field of view falls on the fovea and is in the sharpest focus. Without moving your eyes off that word, notice that words at the beginning or end of the paragraph are not in focus. The images in your peripheral vision are focused by the peripheral retina, and have vague, blurry edges and words that are not as clearly identified. As a result, a large part of the neural function of the eyes is concerned with moving the eyes and head so that important visual stimuli are centered on the fovea. Light falling on the retina causes chemical changes to pigment molecules in the photoreceptors, ultimately leading to a change in the activity of the RGCs. Photoreceptor cells have two parts, the inner segment and the outer segment ( Figure 14.16 ). The inner segment contains the nucleus and other common organelles of a cell, whereas the outer segment is a specialized region in which photoreception takes place. There are two types of photoreceptors—rods and cones—which differ in the shape of their outer segment. The rod-shaped outer segments of the rod photoreceptor contain a stack of membrane-bound discs that contain the photosensitive pigment rhodopsin . The cone-shaped outer segments of the cone photoreceptor contain their photosensitive pigments in infoldings of the cell membrane. There are three cone photopigments, called opsins , which are each sensitive to a particular wavelength of light. The wavelength of visible light determines its color. The pigments in human eyes are specialized in perceiving three different primary colors: red, green, and blue. At the molecular level, visual stimuli cause changes in the photopigment molecule that lead to changes in membrane potential of the photoreceptor cell. A single unit of light is called a photon , which is described in physics as a packet of energy with properties of both a particle and a wave. The energy of a photon is represented by its wavelength, with each wavelength of visible light corresponding to a particular color. Visible light is electromagnetic radiation with a wavelength between 380 and 720 nm. Wavelengths of electromagnetic radiation longer than 720 nm fall into the infrared range, whereas wavelengths shorter than 380 nm fall into the ultraviolet range. Light with a wavelength of 380 nm is blue whereas light with a wavelength of 720 nm is dark red. All other colors fall between red and blue at various points along the wavelength scale. Opsin pigments are actually transmembrane proteins that contain a cofactor known as retinal . Retinal is a hydrocarbon molecule related to vitamin A. When a photon hits retinal, the long hydrocarbon chain of the molecule is biochemically altered. Specifically, photons cause some of the double-bonded carbons within the chain to switch from a cis to a trans conformation. This process is called photoisomerization . Before interacting with a photon, retinal’s flexible double-bonded carbons are in the cis conformation. This molecule is referred to as 11- cis -retinal. A photon interacting with the molecule causes the flexible double-bonded carbons to change to the trans - conformation, forming all- trans -retinal, which has a straight hydrocarbon chain ( Figure 14.17 ). The shape change of retinal in the photoreceptors initiates visual transduction in the retina. Activation of retinal and the opsin proteins result in activation of a G protein. The G protein changes the membrane potential of the photoreceptor cell, which then releases less neurotransmitter into the outer synaptic layer of the retina. Until the retinal molecule is changed back to the 11- cis -retinal shape, the opsin cannot respond to light energy, which is called bleaching. When a large group of photopigments is bleached, the retina will send information as if opposing visual information is being perceived. After a bright flash of light, afterimages are usually seen in negative. The photoisomerization is reversed by a series of enzymatic changes so that the retinal responds to more light energy. The opsins are sensitive to limited wavelengths of light. Rhodopsin, the photopigment in rods, is most sensitive to light at a wavelength of 498 nm. The three color opsins have peak sensitivities of 564 nm, 534 nm, and 420 nm corresponding roughly to the primary colors of red, green, and blue ( Figure 14.18 ). The absorbance of rhodopsin in the rods is much more sensitive than in the cone opsins; specifically, rods are sensitive to vision in low light conditions, and cones are sensitive to brighter conditions. In normal sunlight, rhodopsin will be constantly bleached while the cones are active. In a darkened room, there is not enough light to activate cone opsins, and vision is entirely dependent on rods. Rods are so sensitive to light that a single photon can result in an action potential from a rod’s corresponding RGC. The three types of cone opsins, being sensitive to different wavelengths of light, provide us with color vision. By comparing the activity of the three different cones, the brain can extract color information from visual stimuli. For example, a bright blue light that has a wavelength of approximately 450 nm would activate the “red” cones minimally, the “green” cones marginally, and the “blue” cones predominantly. The relative activation of the three different cones is calculated by the brain, which perceives the color as blue. However, cones cannot react to low-intensity light, and rods do not sense the color of light. Therefore, our low-light vision is—in essence—in grayscale. In other words, in a dark room, everything appears as a shade of gray. If you think that you can see colors in the dark, it is most likely because your brain knows what color something is and is relying on that memory. Interactive Link Watch this video to learn more about a transverse section through the brain that depicts the visual pathway from the eye to the occipital cortex. The first half of the pathway is the projection from the RGCs through the optic nerve to the lateral geniculate nucleus in the thalamus on either side. This first fiber in the pathway synapses on a thalamic cell that then projects to the visual cortex in the occipital lobe where “seeing,” or visual perception, takes place. This video gives an abbreviated overview of the visual system by concentrating on the pathway from the eyes to the occipital lobe. The video makes the statement (at 0:45) that “specialized cells in the retina called ganglion cells convert the light rays into electrical signals.” What aspect of retinal processing is simplified by that statement? Explain your answer. Sensory Nerves Once any sensory cell transduces a stimulus into a nerve impulse, that impulse has to travel along axons to reach the CNS. In many of the special senses, the axons leaving the sensory receptors have a topographical arrangement, meaning that the location of the sensory receptor relates to the location of the axon in the nerve. For example, in the retina, axons from RGCs in the fovea are located at the center of the optic nerve, where they are surrounded by axons from the more peripheral RGCs. Spinal Nerves Generally, spinal nerves contain afferent axons from sensory receptors in the periphery, such as from the skin, mixed with efferent axons travelling to the muscles or other effector organs. As the spinal nerve nears the spinal cord, it splits into dorsal and ventral roots. The dorsal root contains only the axons of sensory neurons, whereas the ventral roots contain only the axons of the motor neurons. Some of the branches will synapse with local neurons in the dorsal root ganglion, posterior (dorsal) horn, or even the anterior (ventral) horn, at the level of the spinal cord where they enter. Other branches will travel a short distance up or down the spine to interact with neurons at other levels of the spinal cord. A branch may also turn into the posterior (dorsal) column of the white matter to connect with the brain. For the sake of convenience, we will use the terms ventral and dorsal in reference to structures within the spinal cord that are part of these pathways. This will help to underscore the relationships between the different components. Typically, spinal nerve systems that connect to the brain are contralateral , in that the right side of the body is connected to the left side of the brain and the left side of the body to the right side of the brain. Cranial Nerves Cranial nerves convey specific sensory information from the head and neck directly to the brain. For sensations below the neck, the right side of the body is connected to the left side of the brain and the left side of the body to the right side of the brain. Whereas spinal information is contralateral, cranial nerve systems are mostly ipsilateral , meaning that a cranial nerve on the right side of the head is connected to the right side of the brain. Some cranial nerves contain only sensory axons, such as the olfactory, optic, and vestibulocochlear nerves. Other cranial nerves contain both sensory and motor axons, including the trigeminal, facial, glossopharyngeal, and vagus nerves (however, the vagus nerve is not associated with the somatic nervous system). The general senses of somatosensation for the face travel through the trigeminal system. 14.2 Central Processing Learning Objectives By the end of this section, you will be able to: Describe the pathways that sensory systems follow into the central nervous system Differentiate between the two major ascending pathways in the spinal cord Describe the pathway of somatosensory input from the face and compare it to the ascending pathways in the spinal cord Explain topographical representations of sensory information in at least two systems Describe two pathways of visual processing and the functions associated with each Sensory Pathways Specific regions of the CNS coordinate different somatic processes using sensory inputs and motor outputs of peripheral nerves. A simple case is a reflex caused by a synapse between a dorsal sensory neuron axon and a motor neuron in the ventral horn. More complex arrangements are possible to integrate peripheral sensory information with higher processes. The important regions of the CNS that play a role in somatic processes can be separated into the spinal cord brain stem, diencephalon, cerebral cortex, and subcortical structures. Spinal Cord and Brain Stem A sensory pathway that carries peripheral sensations to the brain is referred to as an ascending pathway , or ascending tract. The various sensory modalities each follow specific pathways through the CNS. Tactile and other somatosensory stimuli activate receptors in the skin, muscles, tendons, and joints throughout the entire body. However, the somatosensory pathways are divided into two separate systems on the basis of the location of the receptor neurons. Somatosensory stimuli from below the neck pass along the sensory pathways of the spinal cord, whereas somatosensory stimuli from the head and neck travel through the cranial nerves—specifically, the trigeminal system. The dorsal column system (sometimes referred to as the dorsal column–medial lemniscus) and the spinothalamic tract are two major pathways that bring sensory information to the brain ( Figure 14.19 ). The sensory pathways in each of these systems are composed of three successive neurons. The dorsal column system begins with the axon of a dorsal root ganglion neuron entering the dorsal root and joining the dorsal column white matter in the spinal cord. As axons of this pathway enter the dorsal column, they take on a positional arrangement so that axons from lower levels of the body position themselves medially, whereas axons from upper levels of the body position themselves laterally. The dorsal column is separated into two component tracts, the fasciculus gracilis that contains axons from the legs and lower body, and the fasciculus cuneatus that contains axons from the upper body and arms. The axons in the dorsal column terminate in the nuclei of the medulla, where each synapses with the second neuron in their respective pathway. The nucleus gracilis is the target of fibers in the fasciculus gracilis, whereas the nucleus cuneatus is the target of fibers in the fasciculus cuneatus. The second neuron in the system projects from one of the two nuclei and then decussates , or crosses the midline of the medulla. These axons then continue to ascend the brain stem as a bundle called the medial lemniscus . These axons terminate in the thalamus, where each synapses with the third neuron in their respective pathway. The third neuron in the system projects its axons to the postcentral gyrus of the cerebral cortex, where somatosensory stimuli are initially processed and the conscious perception of the stimulus occurs. The spinothalamic tract also begins with neurons in a dorsal root ganglion. These neurons extend their axons to the dorsal horn, where they synapse with the second neuron in their respective pathway. The name “spinothalamic” comes from this second neuron, which has its cell body in the spinal cord gray matter and connects to the thalamus. Axons from these second neurons then decussate within the spinal cord and ascend to the brain and enter the thalamus, where each synapses with the third neuron in its respective pathway. The neurons in the thalamus then project their axons to the spinothalamic tract, which synapses in the postcentral gyrus of the cerebral cortex. These two systems are similar in that they both begin with dorsal root ganglion cells, as with most general sensory information. The dorsal column system is primarily responsible for touch sensations and proprioception, whereas the spinothalamic tract pathway is primarily responsible for pain and temperature sensations. Another similarity is that the second neurons in both of these pathways are contralateral, because they project across the midline to the other side of the brain or spinal cord. In the dorsal column system, this decussation takes place in the brain stem; in the spinothalamic pathway, it takes place in the spinal cord at the same spinal cord level at which the information entered. The third neurons in the two pathways are essentially the same. In both, the second neuron synapses in the thalamus, and the thalamic neuron projects to the somatosensory cortex. The trigeminal pathway carries somatosensory information from the face, head, mouth, and nasal cavity. As with the previously discussed nerve tracts, the sensory pathways of the trigeminal pathway each involve three successive neurons. First, axons from the trigeminal ganglion enter the brain stem at the level of the pons. These axons project to one of three locations. The spinal trigeminal nucleus of the medulla receives information similar to that carried by spinothalamic tract, such as pain and temperature sensations. Other axons go to either the chief sensory nucleus in the pons or the mesencephalic nuclei in the midbrain. These nuclei receive information like that carried by the dorsal column system, such as touch, pressure, vibration, and proprioception. Axons from the second neuron decussate and ascend to the thalamus along the trigeminothalamic tract. In the thalamus, each axon synapses with the third neuron in its respective pathway. Axons from the third neuron then project from the thalamus to the primary somatosensory cortex of the cerebrum. The sensory pathway for gustation travels along the facial and glossopharyngeal cranial nerves, which synapse with neurons of the solitary nucleus in the brain stem. Axons from the solitary nucleus then project to the ventral posterior nucleus of the thalamus. Finally, axons from the ventral posterior nucleus project to the gustatory cortex of the cerebral cortex, where taste is processed and consciously perceived. The sensory pathway for audition travels along the vestibulocochlear nerve, which synapses with neurons in the cochlear nuclei of the superior medulla. Within the brain stem, input from either ear is combined to extract location information from the auditory stimuli. Whereas the initial auditory stimuli received at the cochlea strictly represent the frequency—or pitch—of the stimuli, the locations of sounds can be determined by comparing information arriving at both ears. Sound localization is a feature of central processing in the auditory nuclei of the brain stem. Sound localization is achieved by the brain calculating the interaural time difference and the interaural intensity difference . A sound originating from a specific location will arrive at each ear at different times, unless the sound is directly in front of the listener. If the sound source is slightly to the left of the listener, the sound will arrive at the left ear microseconds before it arrives at the right ear ( Figure 14.20 ). This time difference is an example of an interaural time difference. Also, the sound will be slightly louder in the left ear than in the right ear because some of the sound waves reaching the opposite ear are blocked by the head. This is an example of an interaural intensity difference. Auditory processing continues on to a nucleus in the midbrain called the inferior colliculus . Axons from the inferior colliculus project to two locations, the thalamus and the superior colliculus . The medial geniculate nucleus of the thalamus receives the auditory information and then projects that information to the auditory cortex in the temporal lobe of the cerebral cortex. The superior colliculus receives input from the visual and somatosensory systems, as well as the ears, to initiate stimulation of the muscles that turn the head and neck toward the auditory stimulus. Balance is coordinated through the vestibular system, the nerves of which are composed of axons from the vestibular ganglion that carries information from the utricle, saccule, and semicircular canals. The system contributes to controlling head and neck movements in response to vestibular signals. An important function of the vestibular system is coordinating eye and head movements to maintain visual attention. Most of the axons terminate in the vestibular nuclei of the medulla. Some axons project from the vestibular ganglion directly to the cerebellum, with no intervening synapse in the vestibular nuclei. The cerebellum is primarily responsible for initiating movements on the basis of equilibrium information. Neurons in the vestibular nuclei project their axons to targets in the brain stem. One target is the reticular formation, which influences respiratory and cardiovascular functions in relation to body movements. A second target of the axons of neurons in the vestibular nuclei is the spinal cord, which initiates the spinal reflexes involved with posture and balance. To assist the visual system, fibers of the vestibular nuclei project to the oculomotor, trochlear, and abducens nuclei to influence signals sent along the cranial nerves. These connections constitute the pathway of the vestibulo-ocular reflex (VOR) , which compensates for head and body movement by stabilizing images on the retina ( Figure 14.21 ). Finally, the vestibular nuclei project to the thalamus to join the proprioceptive pathway of the dorsal column system, allowing conscious perception of equilibrium. The connections of the optic nerve are more complicated than those of other cranial nerves. Instead of the connections being between each eye and the brain, visual information is segregated between the left and right sides of the visual field. In addition, some of the information from one side of the visual field projects to the opposite side of the brain. Within each eye, the axons projecting from the medial side of the retina decussate at the optic chiasm . For example, the axons from the medial retina of the left eye cross over to the right side of the brain at the optic chiasm. However, within each eye, the axons projecting from the lateral side of the retina do not decussate. For example, the axons from the lateral retina of the right eye project back to the right side of the brain. Therefore the left field of view of each eye is processed on the right side of the brain, whereas the right field of view of each eye is processed on the left side of the brain ( Figure 14.22 ). A unique clinical presentation that relates to this anatomic arrangement is the loss of lateral peripheral vision, known as bilateral hemianopia. This is different from “tunnel vision” because the superior and inferior peripheral fields are not lost. Visual field deficits can be disturbing for a patient, but in this case, the cause is not within the visual system itself. A growth of the pituitary gland presses against the optic chiasm and interferes with signal transmission. However, the axons projecting to the same side of the brain are unaffected. Therefore, the patient loses the outermost areas of their field of vision and cannot see objects to their right and left. Extending from the optic chiasm, the axons of the visual system are referred to as the optic tract instead of the optic nerve. The optic tract has three major targets, two in the diencephalon and one in the midbrain. The connection between the eyes and diencephalon is demonstrated during development, in which the neural tissue of the retina differentiates from that of the diencephalon by the growth of the secondary vesicles. The connections of the retina into the CNS are a holdover from this developmental association. The majority of the connections of the optic tract are to the thalamus—specifically, the lateral geniculate nucleus . Axons from this nucleus then project to the visual cortex of the cerebrum, located in the occipital lobe. Another target of the optic tract is the superior colliculus. In addition, a very small number of RGC axons project from the optic chiasm to the suprachiasmatic nucleus of the hypothalamus. These RGCs are photosensitive, in that they respond to the presence or absence of light. Unlike the photoreceptors, however, these photosensitive RGCs cannot be used to perceive images. By simply responding to the absence or presence of light, these RGCs can send information about day length. The perceived proportion of sunlight to darkness establishes the circadian rhythm of our bodies, allowing certain physiological events to occur at approximately the same time every day. Diencephalon The diencephalon is beneath the cerebrum and includes the thalamus and hypothalamus. In the somatic nervous system, the thalamus is an important relay for communication between the cerebrum and the rest of the nervous system. The hypothalamus has both somatic and autonomic functions. In addition, the hypothalamus communicates with the limbic system, which controls emotions and memory functions. Sensory input to the thalamus comes from most of the special senses and ascending somatosensory tracts. Each sensory system is relayed through a particular nucleus in the thalamus. The thalamus is a required transfer point for most sensory tracts that reach the cerebral cortex, where conscious sensory perception begins. The one exception to this rule is the olfactory system. The olfactory tract axons from the olfactory bulb project directly to the cerebral cortex, along with the limbic system and hypothalamus. The thalamus is a collection of several nuclei that can be categorized into three anatomical groups. White matter running through the thalamus defines the three major regions of the thalamus, which are an anterior nucleus, a medial nucleus, and a lateral group of nuclei. The anterior nucleus serves as a relay between the hypothalamus and the emotion and memory-producing limbic system. The medial nuclei serve as a relay for information from the limbic system and basal ganglia to the cerebral cortex. This allows memory creation during learning, but also determines alertness. The special and somatic senses connect to the lateral nuclei, where their information is relayed to the appropriate sensory cortex of the cerebrum. Cortical Processing As described earlier, many of the sensory axons are positioned in the same way as their corresponding receptor cells in the body. This allows identification of the position of a stimulus on the basis of which receptor cells are sending information. The cerebral cortex also maintains this sensory topography in the particular areas of the cortex that correspond to the position of the receptor cells. The somatosensory cortex provides an example in which, in essence, the locations of the somatosensory receptors in the body are mapped onto the somatosensory cortex. This mapping is often depicted using a sensory homunculus ( Figure 14.23 ). The term homunculus comes from the Latin word for “little man” and refers to a map of the human body that is laid across a portion of the cerebral cortex. In the somatosensory cortex, the external genitals, feet, and lower legs are represented on the medial face of the gyrus within the longitudinal fissure. As the gyrus curves out of the fissure and along the surface of the parietal lobe, the body map continues through the thighs, hips, trunk, shoulders, arms, and hands. The head and face are just lateral to the fingers as the gyrus approaches the lateral sulcus. The representation of the body in this topographical map is medial to lateral from the lower to upper body. It is a continuation of the topographical arrangement seen in the dorsal column system, where axons from the lower body are carried in the fasciculus gracilis, whereas axons from the upper body are carried in the fasciculus cuneatus. As the dorsal column system continues into the medial lemniscus, these relationships are maintained. Also, the head and neck axons running from the trigeminal nuclei to the thalamus run adjacent to the upper body fibers. The connections through the thalamus maintain topography such that the anatomic information is preserved. Note that this correspondence does not result in a perfectly miniature scale version of the body, but rather exaggerates the more sensitive areas of the body, such as the fingers and lower face. Less sensitive areas of the body, such as the shoulders and back, are mapped to smaller areas on the cortex. Likewise, the topographic relationship between the retina and the visual cortex is maintained throughout the visual pathway. The visual field is projected onto the two retinae, as described above, with sorting at the optic chiasm. The right peripheral visual field falls on the medial portion of the right retina and the lateral portion of the left retina. The right medial retina then projects across the midline through the optic chiasm. This results in the right visual field being processed in the left visual cortex. Likewise, the left visual field is processed in the right visual cortex (see Figure 14.22 ). Though the chiasm is helping to sort right and left visual information, superior and inferior visual information is maintained topographically in the visual pathway. Light from the superior visual field falls on the inferior retina, and light from the inferior visual field falls on the superior retina. This topography is maintained such that the superior region of the visual cortex processes the inferior visual field and vice versa. Therefore, the visual field information is inverted and reversed as it enters the visual cortex—up is down, and left is right. However, the cortex processes the visual information such that the final conscious perception of the visual field is correct. The topographic relationship is evident in that information from the foveal region of the retina is processed in the center of the primary visual cortex. Information from the peripheral regions of the retina are correspondingly processed toward the edges of the visual cortex. Similar to the exaggerations in the sensory homunculus of the somatosensory cortex, the foveal-processing area of the visual cortex is disproportionately larger than the areas processing peripheral vision. In an experiment performed in the 1960s, subjects wore prism glasses so that the visual field was inverted before reaching the eye. On the first day of the experiment, subjects would duck when walking up to a table, thinking it was suspended from the ceiling. However, after a few days of acclimation, the subjects behaved as if everything were represented correctly. Therefore, the visual cortex is somewhat flexible in adapting to the information it receives from our eyes ( Figure 14.24 ). The cortex has been described as having specific regions that are responsible for processing specific information; there is the visual cortex, somatosensory cortex, gustatory cortex, etc. However, our experience of these senses is not divided. Instead, we experience what can be referred to as a seamless percept. Our perceptions of the various sensory modalities—though distinct in their content—are integrated by the brain so that we experience the world as a continuous whole. In the cerebral cortex, sensory processing begins at the primary sensory cortex , then proceeds to an association area , and finally, into a multimodal integration area . For example, the visual pathway projects from the retinae through the thalamus to the primary visual cortex in the occipital lobe. This area is primarily in the medial wall within the longitudinal fissure. Here, visual stimuli begin to be recognized as basic shapes. Edges of objects are recognized and built into more complex shapes. Also, inputs from both eyes are compared to extract depth information. Because of the overlapping field of view between the two eyes, the brain can begin to estimate the distance of stimuli based on binocular depth cues . Interactive Link Watch this video to learn more about how the brain perceives 3-D motion. Similar to how retinal disparity offers 3-D moviegoers a way to extract 3-D information from the two-dimensional visual field projected onto the retina, the brain can extract information about movement in space by comparing what the two eyes see. If movement of a visual stimulus is leftward in one eye and rightward in the opposite eye, the brain interprets this as movement toward (or away) from the face along the midline. If both eyes see an object moving in the same direction, but at different rates, what would that mean for spatial movement? Everyday Connection Depth Perception, 3-D Movies, and Optical Illusions The visual field is projected onto the retinal surface, where photoreceptors transduce light energy into neural signals for the brain to interpret. The retina is a two-dimensional surface, so it does not encode three-dimensional information. However, we can perceive depth. How is that accomplished? Two ways in which we can extract depth information from the two-dimensional retinal signal are based on monocular cues and binocular cues, respectively. Monocular depth cues are those that are the result of information within the two-dimensional visual field. One object that overlaps another object has to be in front. Relative size differences are also a cue. For example, if a basketball appears larger than the basket, then the basket must be further away. On the basis of experience, we can estimate how far away the basket is. Binocular depth cues compare information represented in the two retinae because they do not see the visual field exactly the same. The centers of the two eyes are separated by a small distance, which is approximately 6 to 6.5 cm in most people. Because of this offset, visual stimuli do not fall on exactly the same spot on both retinae unless we are fixated directly on them and they fall on the fovea of each retina. All other objects in the visual field, either closer or farther away than the fixated object, will fall on different spots on the retina. When vision is fixed on an object in space, closer objects will fall on the lateral retina of each eye, and more distant objects will fall on the medial retina of either eye ( Figure 14.25 ). This is easily observed by holding a finger up in front of your face as you look at a more distant object. You will see two images of your finger that represent the two disparate images that are falling on either retina. These depth cues, both monocular and binocular, can be exploited to make the brain think there are three dimensions in two-dimensional information. This is the basis of 3-D movies. The projected image on the screen is two dimensional, but it has disparate information embedded in it. The 3-D glasses that are available at the theater filter the information so that only one eye sees one version of what is on the screen, and the other eye sees the other version. If you take the glasses off, the image on the screen will have varying amounts of blur because both eyes are seeing both layers of information, and the third dimension will not be evident. Some optical illusions can take advantage of depth cues as well, though those are more often using monocular cues to fool the brain into seeing different parts of the scene as being at different depths. There are two main regions that surround the primary cortex that are usually referred to as areas V2 and V3 (the primary visual cortex is area V1). These surrounding areas are the visual association cortex. The visual association regions develop more complex visual perceptions by adding color and motion information. The information processed in these areas is then sent to regions of the temporal and parietal lobes. Visual processing has two separate streams of processing: one into the temporal lobe and one into the parietal lobe. These are the ventral and dorsal streams, respectively ( Figure 14.26 ). The ventral stream identifies visual stimuli and their significance. Because the ventral stream uses temporal lobe structures, it begins to interact with the non-visual cortex and may be important in visual stimuli becoming part of memories. The dorsal stream locates objects in space and helps in guiding movements of the body in response to visual inputs. The dorsal stream enters the parietal lobe, where it interacts with somatosensory cortical areas that are important for our perception of the body and its movements. The dorsal stream can then influence frontal lobe activity where motor functions originate. Disorders of the... Brain: Prosopagnosia The failures of sensory perception can be unusual and debilitating. A particular sensory deficit that inhibits an important social function of humans is prosopagnosia, or face blindness. The word comes from the Greek words prosopa, that means “faces,” and agnosia, that means “not knowing.” Some people may feel that they cannot recognize people easily by their faces. However, a person with prosopagnosia cannot recognize the most recognizable people in their respective cultures. They would not recognize the face of a celebrity, an important historical figure, or even a family member like their mother. They may not even recognize their own face. Prosopagnosia can be caused by trauma to the brain, or it can be present from birth. The exact cause of proposagnosia and the reason that it happens to some people is unclear. A study of the brains of people born with the deficit found that a specific region of the brain, the anterior fusiform gyrus of the temporal lobe, is often underdeveloped. This region of the brain is concerned with the recognition of visual stimuli and its possible association with memories. Though the evidence is not yet definitive, this region is likely to be where facial recognition occurs. Though this can be a devastating condition, people who suffer from it can get by—often by using other cues to recognize the people they see. Often, the sound of a person’s voice, or the presence of unique cues such as distinct facial features (a mole, for example) or hair color can help the sufferer recognize a familiar person. In the video on prosopagnosia provided in this section, a woman is shown having trouble recognizing celebrities, family members, and herself. In some situations, she can use other cues to help her recognize faces. Interactive Link The inability to recognize people by their faces is a troublesome problem. It can be caused by trauma, or it may be inborn. Watch this video to learn more about a person who lost the ability to recognize faces as the result of an injury. She cannot recognize the faces of close family members or herself. What other information can a person suffering from prosopagnosia use to figure out whom they are seeing? 14.3 Motor Responses Learning Objectives By the end of this section, you will be able to: List the components of the basic processing stream for the motor system Describe the pathway of descending motor commands from the cortex to the skeletal muscles Compare different descending pathways, both by structure and function Explain the initiation of movement from the neurological connections Describe several reflex arcs and their functional roles The defining characteristic of the somatic nervous system is that it controls skeletal muscles. Somatic senses inform the nervous system about the external environment, but the response to that is through voluntary muscle movement. The term “voluntary” suggests that there is a conscious decision to make a movement. However, some aspects of the somatic system use voluntary muscles without conscious control. One example is the ability of our breathing to switch to unconscious control while we are focused on another task. However, the muscles that are responsible for the basic process of breathing are also utilized for speech, which is entirely voluntary. Cortical Responses Let’s start with sensory stimuli that have been registered through receptor cells and the information relayed to the CNS along ascending pathways. In the cerebral cortex, the initial processing of sensory perception progresses to associative processing and then integration in multimodal areas of cortex. These levels of processing can lead to the incorporation of sensory perceptions into memory, but more importantly, they lead to a response. The completion of cortical processing through the primary, associative, and integrative sensory areas initiates a similar progression of motor processing, usually in different cortical areas. Whereas the sensory cortical areas are located in the occipital, temporal, and parietal lobes, motor functions are largely controlled by the frontal lobe. The most anterior regions of the frontal lobe—the prefrontal areas—are important for executive functions , which are those cognitive functions that lead to goal-directed behaviors. These higher cognitive processes include working memory , which has been called a “mental scratch pad,” that can help organize and represent information that is not in the immediate environment. The prefrontal lobe is responsible for aspects of attention, such as inhibiting distracting thoughts and actions so that a person can focus on a goal and direct behavior toward achieving that goal. The functions of the prefrontal cortex are integral to the personality of an individual, because it is largely responsible for what a person intends to do and how they accomplish those plans. A famous case of damage to the prefrontal cortex is that of Phineas Gage, dating back to 1848. He was a railroad worker who had a metal spike impale his prefrontal cortex ( Figure 14.27 ). He survived the accident, but according to second-hand accounts, his personality changed drastically. Friends described him as no longer acting like himself. Whereas he was a hardworking, amiable man before the accident, he turned into an irritable, temperamental, and lazy man after the accident. Many of the accounts of his change may have been inflated in the retelling, and some behavior was likely attributable to alcohol used as a pain medication. However, the accounts suggest that some aspects of his personality did change. Also, there is new evidence that though his life changed dramatically, he was able to become a functioning stagecoach driver, suggesting that the brain has the ability to recover even from major trauma such as this. Secondary Motor Cortices In generating motor responses, the executive functions of the prefrontal cortex will need to initiate actual movements. One way to define the prefrontal area is any region of the frontal lobe that does not elicit movement when electrically stimulated. These are primarily in the anterior part of the frontal lobe. The regions of the frontal lobe that remain are the regions of the cortex that produce movement. The prefrontal areas project into the secondary motor cortices, which include the premotor cortex and the supplemental motor area . Two important regions that assist in planning and coordinating movements are located adjacent to the primary motor cortex. The premotor cortex is more lateral, whereas the supplemental motor area is more medial and superior. The premotor area aids in controlling movements of the core muscles to maintain posture during movement, whereas the supplemental motor area is hypothesized to be responsible for planning and coordinating movement. The supplemental motor area also manages sequential movements that are based on prior experience (that is, learned movements). Neurons in these areas are most active leading up to the initiation of movement. For example, these areas might prepare the body for the movements necessary to drive a car in anticipation of a traffic light changing. Adjacent to these two regions are two specialized motor planning centers. The frontal eye fields are responsible for moving the eyes in response to visual stimuli. There are direct connections between the frontal eye fields and the superior colliculus. Also, anterior to the premotor cortex and primary motor cortex is Broca’s area . This area is responsible for controlling movements of the structures of speech production. The area is named after a French surgeon and anatomist who studied patients who could not produce speech. They did not have impairments to understanding speech, only to producing speech sounds, suggesting a damaged or underdeveloped Broca’s area. Primary Motor Cortex The primary motor cortex is located in the precentral gyrus of the frontal lobe. A neurosurgeon, Walter Penfield, described much of the basic understanding of the primary motor cortex by electrically stimulating the surface of the cerebrum. Penfield would probe the surface of the cortex while the patient was only under local anesthesia so that he could observe responses to the stimulation. This led to the belief that the precentral gyrus directly stimulated muscle movement. We now know that the primary motor cortex receives input from several areas that aid in planning movement, and its principle output stimulates spinal cord neurons to stimulate skeletal muscle contraction. The primary motor cortex is arranged in a similar fashion to the primary somatosensory cortex, in that it has a topographical map of the body, creating a motor homunculus (see Figure 14.23 ). The neurons responsible for musculature in the feet and lower legs are in the medial wall of the precentral gyrus, with the thighs, trunk, and shoulder at the crest of the longitudinal fissure. The hand and face are in the lateral face of the gyrus. Also, the relative space allotted for the different regions is exaggerated in muscles that have greater enervation. The greatest amount of cortical space is given to muscles that perform fine, agile movements, such as the muscles of the fingers and the lower face. The “power muscles” that perform coarser movements, such as the buttock and back muscles, occupy much less space on the motor cortex. Descending Pathways The motor output from the cortex descends into the brain stem and to the spinal cord to control the musculature through motor neurons. Neurons located in the primary motor cortex, named Betz cells , are large cortical neurons that synapse with lower motor neurons in the brain stem or in the spinal cord. The two descending pathways travelled by the axons of Betz cells are the corticobulbar tract and the corticospinal tract , respectively. Both tracts are named for their origin in the cortex and their targets—either the brain stem (the term “bulbar” refers to the brain stem as the bulb, or enlargement, at the top of the spinal cord) or the spinal cord. These two descending pathways are responsible for the conscious or voluntary movements of skeletal muscles. Any motor command from the primary motor cortex is sent down the axons of the Betz cells to activate lower motor neurons in either the cranial motor nuclei or in the ventral horn of the spinal cord. The axons of the corticobulbar tract are ipsilateral, meaning they project from the cortex to the motor nucleus on the same side of the nervous system. Conversely, the axons of the corticospinal tract are largely contralateral, meaning that they cross the midline of the brain stem or spinal cord and synapse on the opposite side of the body. Therefore, the right motor cortex of the cerebrum controls muscles on the left side of the body, and vice versa. The corticospinal tract descends from the cortex through the deep white matter of the cerebrum. It then passes between the caudate nucleus and putamen of the basal nuclei as a bundle called the internal capsule . The tract then passes through the midbrain as the cerebral peduncles , after which it burrows through the pons. Upon entering the medulla, the tracts make up the large white matter tract referred to as the pyramids ( Figure 14.28 ). The defining landmark of the medullary-spinal border is the pyramidal decussation , which is where most of the fibers in the corticospinal tract cross over to the opposite side of the brain. At this point, the tract separates into two parts, which have control over different domains of the musculature. Appendicular Control The lateral corticospinal tract is composed of the fibers that cross the midline at the pyramidal decussation (see Figure 14.28 ). The axons cross over from the anterior position of the pyramids in the medulla to the lateral column of the spinal cord. These axons are responsible for controlling appendicular muscles. This influence over the appendicular muscles means that the lateral corticospinal tract is responsible for moving the muscles of the arms and legs. The ventral horn in both the lower cervical spinal cord and the lumbar spinal cord both have wider ventral horns, representing the greater number of muscles controlled by these motor neurons. The cervical enlargement is particularly large because there is greater control over the fine musculature of the upper limbs, particularly of the fingers. The lumbar enlargement is not as significant in appearance because there is less fine motor control of the lower limbs. Axial Control The anterior corticospinal tract is responsible for controlling the muscles of the body trunk (see Figure 14.28 ). These axons do not decussate in the medulla. Instead, they remain in an anterior position as they descend the brain stem and enter the spinal cord. These axons then travel to the spinal cord level at which they synapse with a lower motor neuron. Upon reaching the appropriate level, the axons decussate, entering the ventral horn on the opposite side of the spinal cord from which they entered. In the ventral horn, these axons synapse with their corresponding lower motor neurons. The lower motor neurons are located in the medial regions of the ventral horn, because they control the axial muscles of the trunk. Because movements of the body trunk involve both sides of the body, the anterior corticospinal tract is not entirely contralateral. Some collateral branches of the tract will project into the ipsilateral ventral horn to control synergistic muscles on that side of the body, or to inhibit antagonistic muscles through interneurons within the ventral horn. Through the influence of both sides of the body, the anterior corticospinal tract can coordinate postural muscles in broad movements of the body. These coordinating axons in the anterior corticospinal tract are often considered bilateral, as they are both ipsilateral and contralateral. Interactive Link Watch this video to learn more about the descending motor pathway for the somatic nervous system. The autonomic connections are mentioned, which are covered in another chapter. From this brief video, only some of the descending motor pathway of the somatic nervous system is described. Which division of the pathway is described and which division is left out? Extrapyramidal Controls Other descending connections between the brain and the spinal cord are called the extrapyramidal system . The name comes from the fact that this system is outside the corticospinal pathway, which includes the pyramids in the medulla. A few pathways originating from the brain stem contribute to this system. The tectospinal tract projects from the midbrain to the spinal cord and is important for postural movements that are driven by the superior colliculus. The name of the tract comes from an alternate name for the superior colliculus, which is the tectum. The reticulospinal tract connects the reticular system, a diffuse region of gray matter in the brain stem, with the spinal cord. This tract influences trunk and proximal limb muscles related to posture and locomotion. The reticulospinal tract also contributes to muscle tone and influences autonomic functions. The vestibulospinal tract connects the brain stem nuclei of the vestibular system with the spinal cord. This allows posture, movement, and balance to be modulated on the basis of equilibrium information provided by the vestibular system. The pathways of the extrapyramidal system are influenced by subcortical structures. For example, connections between the secondary motor cortices and the extrapyramidal system modulate spine and cranium movements. The basal nuclei, which are important for regulating movement initiated by the CNS, influence the extrapyramidal system as well as its thalamic feedback to the motor cortex. The conscious movement of our muscles is more complicated than simply sending a single command from the precentral gyrus down to the proper motor neurons. During the movement of any body part, our muscles relay information back to the brain, and the brain is constantly sending “revised” instructions back to the muscles. The cerebellum is important in contributing to the motor system because it compares cerebral motor commands with proprioceptive feedback. The corticospinal fibers that project to the ventral horn of the spinal cord have branches that also synapse in the pons, which project to the cerebellum. Also, the proprioceptive sensations of the dorsal column system have a collateral projection to the medulla that projects to the cerebellum. These two streams of information are compared in the cerebellar cortex. Conflicts between the motor commands sent by the cerebrum and body position information provided by the proprioceptors cause the cerebellum to stimulate the red nucleus of the midbrain. The red nucleus then sends corrective commands to the spinal cord along the rubrospinal tract . The name of this tract comes from the word for red that is seen in the English word “ruby.” A good example of how the cerebellum corrects cerebral motor commands can be illustrated by walking in water. An original motor command from the cerebrum to walk will result in a highly coordinated set of learned movements. However, in water, the body cannot actually perform a typical walking movement as instructed. The cerebellum can alter the motor command, stimulating the leg muscles to take larger steps to overcome the water resistance. The cerebellum can make the necessary changes through the rubrospinal tract. Modulating the basic command to walk also relies on spinal reflexes, but the cerebellum is responsible for calculating the appropriate response. When the cerebellum does not work properly, coordination and balance are severely affected. The most dramatic example of this is during the overconsumption of alcohol. Alcohol inhibits the ability of the cerebellum to interpret proprioceptive feedback, making it more difficult to coordinate body movements, such as walking a straight line, or guide the movement of the hand to touch the tip of the nose. Interactive Link Visit this site to read about an elderly woman who starts to lose the ability to control fine movements, such as speech and the movement of limbs. Many of the usual causes were ruled out. It was not a stroke, Parkinson’s disease, diabetes, or thyroid dysfunction. The next most obvious cause was medication, so her pharmacist had to be consulted. The side effect of a drug meant to help her sleep had resulted in changes in motor control. What regions of the nervous system are likely to be the focus of haloperidol side effects? Ventral Horn Output The somatic nervous system provides output strictly to skeletal muscles. The lower motor neurons, which are responsible for the contraction of these muscles, are found in the ventral horn of the spinal cord. These large, multipolar neurons have a corona of dendrites surrounding the cell body and an axon that extends out of the ventral horn. This axon travels through the ventral nerve root to join the emerging spinal nerve. The axon is relatively long because it needs to reach muscles in the periphery of the body. The diameters of cell bodies may be on the order of hundreds of micrometers to support the long axon; some axons are a meter in length, such as the lumbar motor neurons that innervate muscles in the first digits of the feet. The axons will also branch to innervate multiple muscle fibers. Together, the motor neuron and all the muscle fibers that it controls make up a motor unit. Motor units vary in size. Some may contain up to 1000 muscle fibers, such as in the quadriceps, or they may only have 10 fibers, such as in an extraocular muscle. The number of muscle fibers that are part of a motor unit corresponds to the precision of control of that muscle. Also, muscles that have finer motor control have more motor units connecting to them, and this requires a larger topographical field in the primary motor cortex. Motor neuron axons connect to muscle fibers at a neuromuscular junction. This is a specialized synaptic structure at which multiple axon terminals synapse with the muscle fiber sarcolemma. The synaptic end bulbs of the motor neurons secrete acetylcholine, which binds to receptors on the sarcolemma. The binding of acetylcholine opens ligand-gated ion channels, increasing the movement of cations across the sarcolemma. This depolarizes the sarcolemma, initiating muscle contraction. Whereas other synapses result in graded potentials that must reach a threshold in the postsynaptic target, activity at the neuromuscular junction reliably leads to muscle fiber contraction with every nerve impulse received from a motor neuron. However, the strength of contraction and the number of fibers that contract can be affected by the frequency of the motor neuron impulses. Reflexes This chapter began by introducing reflexes as an example of the basic elements of the somatic nervous system. Simple somatic reflexes do not include the higher centers discussed for conscious or voluntary aspects of movement. Reflexes can be spinal or cranial, depending on the nerves and central components that are involved. The example described at the beginning of the chapter involved heat and pain sensations from a hot stove causing withdrawal of the arm through a connection in the spinal cord that leads to contraction of the biceps brachii. The description of this withdrawal reflex was simplified, for the sake of the introduction, to emphasize the parts of the somatic nervous system. But to consider reflexes fully, more attention needs to be given to this example. As you withdraw your hand from the stove, you do not want to slow that reflex down. As the biceps brachii contracts, the antagonistic triceps brachii needs to relax. Because the neuromuscular junction is strictly excitatory, the biceps will contract when the motor nerve is active. Skeletal muscles do not actively relax. Instead the motor neuron needs to “quiet down,” or be inhibited. In the hot-stove withdrawal reflex, this occurs through an interneuron in the spinal cord. The interneuron’s cell body is located in the dorsal horn of the spinal cord. The interneuron receives a synapse from the axon of the sensory neuron that detects that the hand is being burned. In response to this stimulation from the sensory neuron, the interneuron then inhibits the motor neuron that controls the triceps brachii. This is done by releasing a neurotransmitter or other signal that hyperpolarizes the motor neuron connected to the triceps brachii, making it less likely to initiate an action potential. With this motor neuron being inhibited, the triceps brachii relaxes. Without the antagonistic contraction, withdrawal from the hot stove is faster and keeps further tissue damage from occurring. Another example of a withdrawal reflex occurs when you step on a painful stimulus, like a tack or a sharp rock. The nociceptors that are activated by the painful stimulus activate the motor neurons responsible for contraction of the tibialis anterior muscle. This causes dorsiflexion of the foot. An inhibitory interneuron, activated by a collateral branch of the nociceptor fiber, will inhibit the motor neurons of the gastrocnemius and soleus muscles to cancel plantar flexion. An important difference in this reflex is that plantar flexion is most likely in progress as the foot is pressing down onto the tack. Contraction of the tibialis anterior is not the most important aspect of the reflex, as continuation of plantar flexion will result in further damage from stepping onto the tack. Another type of reflex is a stretch reflex . In this reflex, when a skeletal muscle is stretched, a muscle spindle receptor is activated. The axon from this receptor structure will cause direct contraction of the muscle. A collateral of the muscle spindle fiber will also inhibit the motor neuron of the antagonist muscles. The reflex helps to maintain muscles at a constant length. A common example of this reflex is the knee jerk that is elicited by a rubber hammer struck against the patellar ligament in a physical exam. A specialized reflex to protect the surface of the eye is the corneal reflex , or the eye blink reflex. When the cornea is stimulated by a tactile stimulus, or even by bright light in a related reflex, blinking is initiated. The sensory component travels through the trigeminal nerve, which carries somatosensory information from the face, or through the optic nerve, if the stimulus is bright light. The motor response travels through the facial nerve and innervates the orbicularis oculi on the same side. This reflex is commonly tested during a physical exam using an air puff or a gentle touch of a cotton-tipped applicator. Interactive Link Watch this video to learn more about the reflex arc of the corneal reflex. When the right cornea senses a tactile stimulus, what happens to the left eye? Explain your answer. Interactive Link Watch this video to learn more about newborn reflexes. Newborns have a set of reflexes that are expected to have been crucial to survival before the modern age. These reflexes disappear as the baby grows, as some of them may be unnecessary as they age. The video demonstrates a reflex called the Babinski reflex, in which the foot flexes dorsally and the toes splay out when the sole of the foot is lightly scratched. This is normal for newborns, but it is a sign of reduced myelination of the spinal tract in adults. Why would this reflex be a problem for an adult?
business_law_i_essentials
Chapter Outline 12.1 Unfair Trade Practices 12.2 The Federal Trade Commission Introduction Learning Outcomes Analyze laws pertaining to unfair trade practices and the agency that scrutinizes them.
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12
12.1 Unfair Trade Practices The term “unfair trade practice” describes the use of deceptive, fraudulent, or unethical methods to gain business advantage or to cause injury to a consumer. Unfair trade practices are considered unlawful under the Consumer Protection Act. The purpose of the law is to ensure that consumers have the opportunity to make informed, rational decisions about the goods and services they purchase. Unfair trade practices include false representation of a good or service, targeting vulnerable populations, false advertising, tied selling, false free prize or gift offers, false or deceptive pricing, and non-compliance with manufacturing standards. Alternative names for unfair trade practices are “deceptive trade practices” or “unfair business practices.” Section 5(a) of the Federal Trade Commission Act prohibits “unfair or deceptive acts or practices in or affecting commerce.” Per the rule, unfair practices are those that cause, or are likely to cause, injury to consumers, those that consumers cannot avoid, and those in which the benefits of the product or service do not outweigh the deception. Deceptive practices are defined as those in which the seller misrepresents or misleads the consumer, and the misleading practice is substantial. The Federal Trade Commission (FTC) is a federal agency that enforces consumer protection laws. Consumers may seek recourse for unfair trade practices by suing for compensatory or punitive damages. Plaintiffs do not have to prove intent. Showing that the practice itself was unfair or deceptive is sufficient. Unfair Trade Practices and Examples Product Guarantees and False Endorsements Companies must be prepared to honor product guarantees. For example, if a product is advertised with a 50 percent money-back guarantee, then that must be provided to customers who meet the requirement(s) attached to the guarantee. Similarly, companies may not create false endorsements and testimonials about their products. Unfair Advertising False advertising includes the misrepresentation of a product, service, or price. It may be more expansively defined to include unfair sales strategies, such as advertising one item and then selling another item in its place, e.g., one that is higher priced, lower quality and/or less in demand. This method is most commonly referred to as “bait and switch.” Additional examples of unfair advertising include incorrect pricing, fake endorsements, deceptive guarantees, making false statements, and providing descriptions that exaggerate the performance of the product or service. Example For months, Ivan had searched for just the right window curtain to match the décor of his new high rise condo. Finally, while browsing through Amazon, he saw two gray velvet curtains that featured a damask pattern, with taupe and gold accents and specks of ice blue glitter accents. He could not have designed a more perfect color palette for the window treatments if he tried. Moreover, the velvet blackout touch was just what he needed. Excited, he hit the “Buy Now” button and waited a couple of days for his order to arrive. When it did, what a huge disappointment! He could see, if he stared long and hard enough, how someone with a vivid imagination might consider the curtain to be an abstract interpretation of what was advertised. However, most people would see that the product was not at all close to what was advertised. The velvet was closer to linen, the damask pattern was closer to swirls, and the taupe and gold accents with specks of ice blue were closer to silver and purple, with specks of mauve. After running a Google reverse image search of the original product photo, he saw it featured in an interior design magazine. When Ivan looked up the product endorsements and reviews, he saw that all of the reviewers had only posted reviews for that particular seller’s products, and that they had posted nothing but glowing reviews for each of the products. It was clear to Ivan that the seller was guilty of false advertising, as well as faking endorsements. Ivan has enough information to submit a consumer complaint to the Federal Trade Commission. Taking Advantage of Customers The FTC also pays particular attention to business ventures that target vulnerable populations. For example, some telemarketing efforts employ intense pressuring tactics to target seniors and people who don’t speak English. Example Devin is involved in the telemarketing of spy gadgets, such as bugs and bug detectors. He has had a lot of trouble finding a market for these products. One day, he speaks with an older citizen who asks him about the benefits of the bug detector. Devin starts to knowingly make unsubstantiated claims that there have been news reports that home bugging is on the rise. His false claims works like a charm. Spooked, the elderly customer buys the most expensive bug detector product. Seeing his success, Devin purchases a report of households in his geographic selling area that are headed by people over the age of 70. Over the next few months, his sales increase at an explosive rate. When he is recognized by management for his leading sales numbers, they also inquire about the secret to his success as they seek to replicate it in training materials for other sales professionals. When Devin proudly explains his tactics, he is terminated by the company. The company calls the customers impacted by his false claims, explains that there was a misrepresentation by one their sales associates regarding the scope of known bugging activity, allows them to keep their bug detectors, and refunds them the money they spent purchasing the products. The sales associate engaged in unfair trade practices, but the company took appropriate steps to correct it. Misrepresenting a Product At times, the FTC may be quite technical in its definition of certain terms. For this reason, companies should be very clear about their usage of various phrases and words. For example, the word “new” may only be used to refer to a product that is less than six months old. Other terms may be the subject of debate or litigation, such as whether a lotion will actually “rejuvenate” skin or whether a tablet will actually “cure” baldness. Indeed, a sweater should not be called “wool” unless that is its complete composition. There are many examples, so it is important for businesses to have an understanding of the FTC’s rules on this topic. Giving Misleading Price Information The FTC sanctions misleading price information as an unfair trade practice. Examples of misleading price information include false sales in which a “limited time offer” might actually be available forever, or running a “Going Out of Business” sale without any plans to go out of business while advertising that items are discounted, although the prices have not changed. Example A brick and mortar store has an online promotion for a “buy one, get one” offer for the season’s hottest new phone, stating that the offer is only available on Black Friday. The store opens at 5:00 a.m., and customers start lining up with their sleeping bags in tow the evening prior to the morning opening time. After customers almost stampede one another, they learn that they will have to also purchase a phone plan that is inflated by 100% of its regular price to qualify for the deal. Nowhere in the literature or promotions was the phone plan, or its over-inflated price, mentioned as a requirement to get the buy one get one free phone deal. Failing to Disclose Pertinent Information Merchants must disclose facts that would reasonably influence the consumer’s decision to make a purchase. Withholding pertinent information from customers may be viewed by the FTC as equal in severity to the process of using overtly incorrect or deceptive information. For example, sellers should always disclose the full price of their products or services before accepting payment for them. 12.2 The Federal Trade Commission The FTC was created in 1914 to address the problem of monopolies and trusts. Following the Civil War, a wave of consolidation and growth among companies triggered increased public debate. Through handshake agreements, issuance of stock, and pooling arrangements, companies could fix prices and outputs, thus effectively stopping competition and raising consumer prices. A substantial number of mergers gave control over key industries to small groups of businesses. Where companies did not merge, other arrangements were made to have a similar effect. Conglomerates controlled most of the relevant industries that produced household necessities. Goods used in production were also the product of highly concentrated trusts, such as the United States Steel Corporation and the International Paper Company. Concerns about industrialization and a changing economy, with shifting norms for personal lives, triggered antitrust sentiment. The perceived unfairness and fears caused by the consolidation of businesses created strong anti-business sentiment and increasing cries for price controls to be considered as a remedy for heavily concentrated industries. These organizations posed economic and social problems that became a large social concern. In response, the Federal Trade Commission (FTC) was created with broad powers to investigate and propose formal recommendations to companies about their competitive practices. The FTC did not formally have a consumer protection mission until the passage of the Wheeler-Lea Act in 1938. This act gave the FTC the power to combat false advertising for any foods, drugs, medical devices, or cosmetics. In addition to the Wheeler-Lea Act, subsequent amendments to the FTC Act, as well as judicial respect toward the agency, broadened the power and jurisdiction of the FTC. Today, in addition to its original antitrust roots, the FTC enforces consumer protection laws. Bureaus of the FTC Several bureaus now stand in support of the FTC’s efforts. Bureau of Consumer Protection The Bureau of Consumer Protection protects consumers against unfair trade practices. Bureau attorneys enforce consumer protection laws issued by the FTC. In addition to enforcement actions, the Bureau’s functions include investigations and consumer and business training. Unfair trade practices in advertising and marketing are a main focus, as well as privacy, financial products and practices, and identity protection. The Bureau also manages the United States National Do Not Call Registry and investigates telemarketing fraud. Bureau of Competition The Bureau of Competition’s purpose is to eliminate and prevent “anticompetitive” business practices related to the enforcement of antitrust laws. The FTC and the Department of Justice share responsibility for enforcement of antitrust laws. Bureau of Economics The Bureau of Economics supports the Bureau of Competition and Bureau of Consumer Protection by providing subject matter expertise regarding the economic impacts of FTC legislative activity. FTC Activities The FTC investigates issues raised through a number of sources, including consumer, business, and media reports. If the FTC concludes that there was unlawful conduct, it may seek several forms of recourse. These include the pursuit of voluntary compliance through a consent order, the submission and filing of administrative complaints, or the initiation of a federal action and litigation. The FTC has the power to create rules regarding widespread industry practices. Rules created in this fashion to address systemic issues are called trade rules.
business_law_i_essentials
Chapter Outline 1.1 Basic American Legal Principles 1.2 Sources and Types of Law 1.3 Important Business Laws and Regulations Introduction Learning Outcome Describe the foundation and sources that establish American law.
[ { "answer": { "ans_choice": 1, "ans_text": "b" }, "bloom": null, "hl_context": "<hl> Based on the British legal system , the American legal system is divided into a federal system and a state and local system . <hl> The overall goal of both systems is to provide order and a means of dispute settlement , as well as to protect citizens ’ rights .", "hl_sentences": "Based on the British legal system , the American legal system is divided into a federal system and a state and local system .", "question": { "cloze_format": "The country that the United States legal system is derived from is ___.", "normal_format": "What country is the United States legal system derived from?", "question_choices": [ "Germany.", "United Kingdom.", "United States of America.", "Canada." ], "question_id": "fs-idm389679760", "question_text": "What country is the United States legal system derived from?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 3, "ans_text": "All of the above." }, "bloom": null, "hl_context": "<hl> Congruent with the goal of establishing standards and promoting consistency , laws are also used to promote , provide , and maintain order . <hl> <hl> Maintaining Order <hl> <hl> The American legal system follows the British Common Law system , which is designed to leverage past judicial reasoning , while also promoting fairness through consistency . <hl> Judges in the Common Law system help shape the law through their rulings and interpretations . This body of past decisions is known as case law . Judges use case law to inform their own rulings . Indeed , judges rely on precedent , i . e . , previous court rulings on similar cases , for ruling on their own cases . <hl> Promoting Consistency <hl> <hl> The American legal system was developed with the goal of establishing a set of standards that outline what is to be considered minimally acceptable behavior . <hl> Broadly speaking , federal laws are those that all United States citizens are expected to follow . State and local laws may often be similar to federal laws , but they may also differ quite a bit , and only govern the state ’ s citizens . <hl> Establishing Standards <hl>", "hl_sentences": "Congruent with the goal of establishing standards and promoting consistency , laws are also used to promote , provide , and maintain order . Maintaining Order The American legal system follows the British Common Law system , which is designed to leverage past judicial reasoning , while also promoting fairness through consistency . Promoting Consistency The American legal system was developed with the goal of establishing a set of standards that outline what is to be considered minimally acceptable behavior . Establishing Standards", "question": { "cloze_format": "The function of law in the United States is to ___.", "normal_format": "What is the function of law in the United States?", "question_choices": [ "Establish standards.", "Promote consistency.", "Promote, provide, and maintain order.", "All of the above." ], "question_id": "fs-idm364650400", "question_text": "What is the function of law in the United States?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 0, "ans_text": "a" }, "bloom": null, "hl_context": "As discussed in the previous section , the United States follows the common law legal tradition of English law . Judges in the Common Law system help shape the law through their rulings and interpretations . This body of past decisions is known as case law , which is used by judges to inform their own rulings . <hl> In fact , judges rely on precedent , i . e . , previous court rulings on similar cases , when determining the ruling in their own cases . <hl> The American legal system follows the British Common Law system , which is designed to leverage past judicial reasoning , while also promoting fairness through consistency . Judges in the Common Law system help shape the law through their rulings and interpretations . This body of past decisions is known as case law . Judges use case law to inform their own rulings . <hl> Indeed , judges rely on precedent , i . e . , previous court rulings on similar cases , for ruling on their own cases . <hl>", "hl_sentences": "In fact , judges rely on precedent , i . e . , previous court rulings on similar cases , when determining the ruling in their own cases . Indeed , judges rely on precedent , i . e . , previous court rulings on similar cases , for ruling on their own cases .", "question": { "cloze_format": "As a judge, Baxter applies common law rules. These rules develop from ___.", "normal_format": "As a judge, Baxter applies common law rules. What are these rules develop from?", "question_choices": [ "decisions of the courts in legal disputes.", "regulations issued by administrative agencies.", "statutes enacted by Congress and the state legislatures.", "uniform laws drafted by legal scholars." ], "question_id": "fs-idm348283856", "question_text": "As a judge, Baxter applies common law rules. These rules develop from:" }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 0, "ans_text": "a" }, "bloom": null, "hl_context": "Within the business law context , torts may involve either intentional torts or negligence . Additionally , companies involved in certain industries should consider the risk of product liability . <hl> Product liability involves a legal action against a company by a consumer for a defective product that caused loss or harm to the customer . <hl> There are several theories regarding recovery under product liability . These include contract theories that deal with the product warranty , which details the promises of the nature of the product sold to customers . The contract product warranty theories are Express Warranty , Implied Warranty of Merchantability , and Implied Warranty of Fitness . Tort theories deal with a consumer claim that the company was negligent , and therefore caused either bodily harm , emotional harm , or monetary loss to the plaintiff . The tort liability theories that can be used in this context are negligence ( failure to take proper care in something ) , strict liability ( imposition of liability without a finding of fault ) , and acts committed under Restatement ( Third ) of Torts ( basic elements of the tort action for liability for accidental personal injury and property damage , as well as liability for emotional harm ) .", "hl_sentences": "Product liability involves a legal action against a company by a consumer for a defective product that caused loss or harm to the customer .", "question": { "cloze_format": "The legislature of the state of Wyoming enacts a new statute that sets standards for the liability of businesses selling defective products. This statute applies in ___ .", "normal_format": "The legislature of the state of Wyoming enacts a new statute that sets standards for the liability of businesses selling defective products. What is this statute apply in?", "question_choices": [ "Wyoming only.", "only Wyoming and its bordering states.", "all states.", "all states but only to matters not covered by other states’ laws." ], "question_id": "fs-idm374558080", "question_text": "The legislature of the state of Wyoming enacts a new statute that sets standards for the liability of businesses selling defective products. This statute applies in:" }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 3, "ans_text": "d" }, "bloom": null, "hl_context": "America , as diverse as its fifty states , is also governed by fifty different state constitutions , state governments , and state courts . <hl> Each has its own legislative , executive , and judicial branches . <hl> <hl> States are empowered to create legislation that is related to matters not preempted by the federal Constitution and federal laws . <hl> Most cases involve state law issues and are litigated in state courts . <hl> American law mainly originates from constitutional law , statutory law , treaties , administrative regulations , and common law ( which includes case law ) . <hl>", "hl_sentences": "Each has its own legislative , executive , and judicial branches . States are empowered to create legislation that is related to matters not preempted by the federal Constitution and federal laws . American law mainly originates from constitutional law , statutory law , treaties , administrative regulations , and common law ( which includes case law ) .", "question": { "cloze_format": "Four sources of law in the U.S. legal system are ___", "normal_format": "What are the four sources of law in the U.S legal system?", "question_choices": [ "Constitutional law, criminal law, civil law, and maritime law.", "Federal law, state law, international law, and maritime law.", "Statutory law, case law, equity, and common law.", "Constitutional law, judicial law, legislative law, and administrative law." ], "question_id": "fs-idm269333600", "question_text": "Four sources of law in the U.S. legal system are:" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 2, "ans_text": "United States Code." }, "bloom": null, "hl_context": "When a bill becomes a federal law , it is assigned a law number and prepared for publication by the Office of the Federal Register ( OFR ) of the National Archives and Records Administration ( NARA ) . <hl> Public laws are also given legal statutory citation by the OFR and are incorporated into the United States Code ( USC ) . <hl> The United States Constitution is the foremost law of the land . The Constitution ’ s first ten amendments are referred to as the Bill of Rights , which offers specific protections of individual liberty and justice . Additionally , the Bill of Rights restricts certain powers of government . The Constitution empowers federal law making by giving Congress the power to enact statutes for certain limited purposes , like regulating interstate commerce . <hl> The United States Code officially compiles and codifies the federal statutes . <hl> The American legal system is made up of many types of codified forms of law , with the United States Constitution being the pre-eminent source of American law . The Constitution establishes the boundaries of federal law , and it must be followed by all citizens , organizations , and entities . It includes Congressional acts , Senate-ratified treaties , executive regulations , and federal case law . <hl> The United States Code ( “ USC ” ) compiles these laws . <hl>", "hl_sentences": "Public laws are also given legal statutory citation by the OFR and are incorporated into the United States Code ( USC ) . The United States Code officially compiles and codifies the federal statutes . The United States Code ( “ USC ” ) compiles these laws .", "question": { "cloze_format": "You can find a codification of federal laws in (the) ___.", "normal_format": "Where can you find a codification of federal laws?", "question_choices": [ "The library.", "Federal Court.", "United States Code.", "U.S. Library of Congress." ], "question_id": "fs-idm268081456", "question_text": "Where can you find a codification of federal laws?" }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 3, "ans_text": "Rules adopted by administrative agencies." }, "bloom": null, "hl_context": "Laws differ from regulations in that laws are passed by either the U . S . Congress or state congresses . <hl> Regulations , by contrast , are standards and rules adopted by administrative agencies that govern how laws will be enforced . <hl>", "hl_sentences": "Regulations , by contrast , are standards and rules adopted by administrative agencies that govern how laws will be enforced .", "question": { "cloze_format": "Regulations are ___ .", "normal_format": "What are regulations?", "question_choices": [ "Laws passed by Congress.", "Rules made by local governments.", "Derived from decisions made by judges.", "Rules adopted by administrative agencies." ], "question_id": "fs-idm265603200", "question_text": "Regulations are:" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 0, "ans_text": "True." }, "bloom": null, "hl_context": "Since the start of the 20th century , broad interpretations of the Constitution ’ s Commerce and Spending Clauses have expanded the reach of federal law into many areas . Indeed , its reach in some areas is now so broad that it preempts virtually all state law . Thus , the Constitution ’ s Commerce Clause has been interpreted to allow federal lawmaking and enforcement that applies to many aspects of business activity . <hl> Additionally , the Constitution ’ s Bill of Rights extends some protections to business entities that are also constitutionally guaranteed to individuals <hl>", "hl_sentences": "Additionally , the Constitution ’ s Bill of Rights extends some protections to business entities that are also constitutionally guaranteed to individuals", "question": { "cloze_format": "It is ___ that some of the rights in the Constitution’s Bill of Rights extends to Corporations.", "normal_format": "Some of the rights in the Constitution’s Bill of Rights extends to Corporations.", "question_choices": [ "True.", "False." ], "question_id": "fs-idm273602176", "question_text": "Some of the rights in the Constitution’s Bill of Rights extends to Corporations." }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 2, "ans_text": "c" }, "bloom": null, "hl_context": "In addition to the federal court and individual state systems , there are also a variety of mechanisms that companies can use to resolve disputes . They are collectively called alternative dispute resolution ( “ ADR ” ) , and they include mediation , settlement , and arbitration . <hl> Many states now require companies to resolve legal disputes using ADR before the initiation of any lawsuit to encourage speedy resolution , cost and time containment , and reduced judicial dockets . <hl> <hl> Traditional litigation remains an option in most cases if other efforts fail or are refused . <hl>", "hl_sentences": "Many states now require companies to resolve legal disputes using ADR before the initiation of any lawsuit to encourage speedy resolution , cost and time containment , and reduced judicial dockets . Traditional litigation remains an option in most cases if other efforts fail or are refused .", "question": { "cloze_format": "Forms of Alternative Dispute Resolution (“ADR”) include all of the following except ___\n", "normal_format": "Forms of Alternative Dispute Resolution (“ADR”) include all of the following except which one?", "question_choices": [ "Mediation.", "Settlement.", "Litigation.", "Arbitration." ], "question_id": "fs-idm271886464", "question_text": "Forms of Alternative Dispute Resolution (“ADR”) include all of the following except:" }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 3, "ans_text": "Damages." }, "bloom": null, "hl_context": "The imposition of criminal liability is one method used to regulate companies . The extent of corporate liability found in an offensive act determines whether a company will be held liable for the acts and omissions of its employees . <hl> Criminal consequences may include penalties , such as prison , fines and / or community service . <hl> <hl> In addition to criminal liability , civil law remedies are usually available , e . g . , the award of damages and injunctions , which may include penalties . <hl> Most jurisdictions apply both criminal and civil systems .", "hl_sentences": "Criminal consequences may include penalties , such as prison , fines and / or community service . In addition to criminal liability , civil law remedies are usually available , e . g . , the award of damages and injunctions , which may include penalties .", "question": { "cloze_format": "Consequences of being convicted a crime does not include ___", "normal_format": "Which of the following is NOT a consequence of being convicted of a crime?", "question_choices": [ "Prison.", "Fines.", "Community service.", "Damages." ], "question_id": "fs-idm275523344", "question_text": "Consequences of being convicted a crime include all of the following except:" }, "references_are_paraphrase": 0 } ]
1
1.1 Basic American Legal Principles The American legal system has its roots in the British legal system. It was developed with the purpose of establishing standards for acceptable conduct, proscribing punishment for violations as a deterrent, establishing systems for enforcement, and peacefully resolving disputes. The ultimate goal of the American legal system is promotion of the common good. Establishing Standards The American legal system was developed with the goal of establishing a set of standards that outline what is to be considered minimally acceptable behavior. Broadly speaking, federal laws are those that all United States citizens are expected to follow. State and local laws may often be similar to federal laws, but they may also differ quite a bit, and only govern the state’s citizens. Promoting Consistency The American legal system follows the British Common Law system, which is designed to leverage past judicial reasoning, while also promoting fairness through consistency. Judges in the Common Law system help shape the law through their rulings and interpretations. This body of past decisions is known as case law . Judges use case law to inform their own rulings. Indeed, judges rely on precedent , i.e., previous court rulings on similar cases, for ruling on their own cases. All U.S. states, except Louisiana, have enacted “reception statutes,” stating that the judge-made common law of England is the law of the state to the extent that it does not conflict with the state’s current laws. However, the body of American law is now so robust that American cases rarely cite English materials, except for a British classic or a famous old case. Additionally, foreign law is not cited as binding precedent. Therefore, the current American practice of the common law tradition refers more to the process of judges looking to the precedent set jurisdictionally, and substantially similar to, American case law. Maintaining Order Congruent with the goal of establishing standards and promoting consistency, laws are also used to promote, provide, and maintain order. Resolving Disputes Conflicts are to be expected given people’s varying needs, desires, objectives, values systems, and perspectives. The American legal system provides a formal means for resolving conflicts through the courts. In addition to the federal court and individual state systems, there are also several informal means for resolving disputes that are collectively called alternative dispute resolution (ADR). Examples of these are mediation and arbitration. Protecting Liberties and Rights The United States Constitution and state laws provide people with many liberties and rights. American laws operate with the purpose and function of protecting these liberties and rights from violations by persons, companies, governments, or other entities. Based on the British legal system, the American legal system is divided into a federal system and a state and local system. The overall goal of both systems is to provide order and a means of dispute settlement, as well as to protect citizens’ rights. Clearly, the purposes of the American legal system are broad and well-considered. 1.2 Sources and Types of Law The American legal system is made up of many types of codified forms of law, with the United States Constitution being the pre-eminent source of American law. The Constitution establishes the boundaries of federal law, and it must be followed by all citizens, organizations, and entities. It includes Congressional acts, Senate-ratified treaties, executive regulations, and federal case law. The United States Code (“USC”) compiles these laws. American law mainly originates from constitutional law, statutory law, treaties, administrative regulations, and common law (which includes case law). The Constitution The United States Constitution is the foremost law of the land. The Constitution’s first ten amendments are referred to as the Bill of Rights, which offers specific protections of individual liberty and justice. Additionally, the Bill of Rights restricts certain powers of government. The Constitution empowers federal law making by giving Congress the power to enact statutes for certain limited purposes, like regulating interstate commerce. The United States Code officially compiles and codifies the federal statutes. American Common Law As discussed in the previous section, the United States follows the common law legal tradition of English law. Judges in the Common Law system help shape the law through their rulings and interpretations. This body of past decisions is known as  case law , which is used by judges to inform their own rulings. In fact, judges rely on precedent , i.e., previous court rulings on similar cases, when determining the ruling in their own cases. An example of how case law works is the case of the State v. Wayfair Inc. (2017 SD 56, 901 N.W.2d 754 (S.D. 2017), cert. granted, 138 S. Ct. 735 (2018)), in which the South Dakota Supreme Court held that a state law requiring internet retailers without an in-state physical presence to remit sales tax was unconstitutional. Unless this ruling is overruled by the United States Supreme Court, then it becomes part of the case law and precedent set in that state, and it will be followed by subsequent rulings when similar cases are filed. Federal Law The Constitution empowers federal law making by giving Congress the power to enact statutes for certain limited purposes, like regulating interstate commerce. Federal law preempts conflicting state and local laws. However, federal preemption is not without limits, insofar as states each have their own constitution and are considered sovereign. Therefore, federal law may only preempt state law if it is enacted within the limited powers that are enumerated and granted to Congress in the Constitution. Broad interpretations of the Constitution’s Commerce and Spending Clauses have expanded the reach of federal law into many areas. Indeed, its reach in some areas, such as aviation and railroads, is now so broad that it preempts virtually all state law. In other areas, such as family law, lawmaking continues to be left to the states. Finally, a number of powerful federal and state laws coexist in areas such as antitrust, trademark, employment law, and others. Statutes When a bill becomes a federal law, it is assigned a law number and prepared for publication by the Office of the Federal Register (OFR) of the National Archives and Records Administration (NARA). Public laws are also given legal statutory citation by the OFR and are incorporated into the United States Code (USC). Regulations Laws differ from regulations in that laws are passed by either the U.S. Congress or state congresses. Regulations, by contrast, are standards and rules adopted by administrative agencies that govern how laws will be enforced. Federal agencies often enjoy broad rulemaking authority when Congress acts to grant them this power. Called “regulations,” these agency rules normally carry the force of law, as long as they demonstrate a reasonable interpretation of the relevant statutes. For example, the Environmental Protection Agency (EPA) has established regulations for businesses and their emission and disposal of pollutants to protect the environment. The EPA has the authority to enforce these regulations when a business violates them, and such enforcement is usually done by fining the company or by using other means. The Administrative Procedure Act (APA) enables the adoption of regulations, which are codified and incorporated into the Code of Federal Regulations (CFR). Federal agencies frequently draft and distribute forms, manuals, policy statements, letters, and rulings. Though these may be considered as persuasive authority by the courts, they do not carry the same force as law. In other words, if a person or business questions a regulation of a government agency, saying it is unconstitutional, and that party is successful in proving it, then the regulation is not enforced and the agency will need to revise it or remove it. State Law America, as diverse as its fifty states, is also governed by fifty different state constitutions, state governments, and state courts. Each has its own legislative, executive, and judicial branches. States are empowered to create legislation that is related to matters not preempted by the federal Constitution and federal laws. Most cases involve state law issues and are litigated in state courts. Local Law In addition to federal and state law, municipalities, towns or cities, and counties may enact their own laws that do not conflict with state or federal laws. As demonstrated, American law does not draw from one source alone; instead, it is derived from many sources. 1.3 Important Business Laws and Regulations Business law is a very expansive area of the law. It primarily addresses issues related to the creation of new businesses, which arise as existing companies deal with the public, government, and other companies. Business law consists of many legal disciplines, including contracts, tax law, corporate law, intellectual property, real estate, sales, immigration law, employment law, bankruptcy, and others. As noted, business law touches upon a number of other legal areas, practices, and concerns. Some of the most important of these, which are discussed in this section, are disputes and dispute settlement, business ethics and social responsibility, business and the United States Constitution, criminal liability, torts, contracts, labor and employment law, Unfair Trade Practices and the Federal Trade Commission, international law, and securities regulation. Though they are discussed in much more depth in later chapters, the following gives a brief overview. Disputes and Dispute Settlement In addition to the federal court and individual state systems, there are also a variety of mechanisms that companies can use to resolve disputes. They are collectively called alternative dispute resolution (“ADR”), and they include mediation, settlement, and arbitration. Many states now require companies to resolve legal disputes using ADR before the initiation of any lawsuit to encourage speedy resolution, cost and time containment, and reduced judicial dockets. Traditional litigation remains an option in most cases if other efforts fail or are refused. Business Ethics and Social Responsibility In the routine course of business, employees are often required to make decisions. Business ethics outline the ethical model, or framework, that companies expect employees to follow when making these decisions, as well as the behavior that the companies deem acceptable. Sound and ethical decision making can also help companies avoid legal liability and exposure. Typically, an ethics code and/or a code of conduct details a company’s requirements and guidelines, while also serving as a key corporate governance tool. In addition to business ethics, companies must also consider their social responsibility and the laws related to it, such as consumer and investor protections, environmental ethics, marketing ethics, and ethical issues in financial management. Business and the United States Constitution Since the start of the 20th century, broad interpretations of the Constitution’s Commerce and Spending Clauses have expanded the reach of federal law into many areas. Indeed, its reach in some areas is now so broad that it preempts virtually all state law. Thus, the Constitution’s Commerce Clause has been interpreted to allow federal lawmaking and enforcement that applies to many aspects of business activity. Additionally, the Constitution’s Bill of Rights extends some protections to business entities that are also constitutionally guaranteed to individuals For example, on January 21, 2010, in Citizens United v. Federal Election Commission , 558 U.S. 310 (2010), the U.S. Supreme Court heard the issue of whether the government can ban political spending by corporations in candidate elections. The Court ruled that corporations have the same Constitutional right to free speech as individuals, and thus lifted the restrictions on contributions. Criminal Liability The imposition of criminal liability is one method used to regulate companies. The extent of corporate liability found in an offensive act determines whether a company will be held liable for the acts and omissions of its employees. Criminal consequences may include penalties, such as prison, fines and/or community service. In addition to criminal liability, civil law remedies are usually available, e.g., the award of damages and injunctions, which may include penalties. Most jurisdictions apply both criminal and civil systems. Torts Within the business law context, torts may involve either intentional torts or negligence. Additionally, companies involved in certain industries should consider the risk of product liability. Product liability involves a legal action against a company by a consumer for a defective product that caused loss or harm to the customer. There are several theories regarding recovery under product liability. These include contract theories that deal with the product warranty, which details the promises of the nature of the product sold to customers. The contract product warranty theories are Express Warranty, Implied Warranty of Merchantability, and Implied Warranty of Fitness. Tort theories deal with a consumer claim that the company was negligent, and therefore caused either bodily harm, emotional harm, or monetary loss to the plaintiff. The tort liability theories that can be used in this context are negligence (failure to take proper care in something), strict liability (imposition of liability without a finding of fault), and acts committed under Restatement (Third) of Torts (basic elements of the tort action for liability for accidental personal injury and property damage, as well as liability for emotional harm). Contracts The main function of a contract is to document promises that are enforceable by law. The key to an agreement or contract is that there must be an offer and acceptance of the terms of that offer. Sales contracts normally involve the sale of goods and include price terms, quantity and cost, how the terms of the contract will be performed, and method of delivery. Employment and Labor Law Employment and labor law is a very broad discipline that covers a broad array of laws and regulations involving employer/employee rights and responsibilities in the workplace. This law includes worker protection and safety laws, such as OSHA, and worker immigration laws, such as the Immigration Reform and Control Act, which imposes sanctions on employers for knowingly hiring illegal immigrants. Other notable areas of employment and labor law include, but are not limited to, the National Labor Relations Act, which deals with union and management relations, as well as Equal Opportunity in Employment laws, which provide workers with protections against discrimination in the workplace, e.g., Title VII, the Americans with Disabilities Act, Age Discrimination in Employment Act, and others. Antitrust Law Antitrust legislation includes both federal and state laws regulating companies’ conduct and organization. The purpose of such regulation is to allow consumers to benefit from the promotion of fair competition. The main statutes implicated by antitrust law are the Sherman Act of 1890, the Clayton Act of 1914, and the Federal Trade Commission Act of 1914. These Acts discourage the restraint of trade by prohibiting the creation of cartels and other collusive practices. Additionally, they encourage competition by restricting the mergers and acquisitions of certain organizations. Finally, they prohibit the creation and abuse of monopoly power. Actions may be brought in courts to enforce antitrust laws by the Federal Trade Commission (“FTC”), the U.S. Department of Justice, state governments, and private parties. Unfair Trade Practices and the Federal Trade Commission The term “unfair trade practices” is broadly used and refers to any deceptive or fraudulent business practice or act that causes injury to a consumer. Some examples include, but are not limited to, false representations of a good or service including deceptive pricing, non-compliance with manufacturing standards, and false advertising. The FTC investigates allegations of unfair trade practices raised by consumers and businesses, pre-merger notification filings, congressional inquiries, or reports in the media and may seek voluntary compliance by offending businesses through a consent order, administrative complaints, or federal litigation. Securities Regulation Securities regulation involves both federal and state regulation of securities and stocks by governmental regulatory agencies. At times, it may also involve the regulations of exchanges like the New York Stock Exchange, as well as the rules of self-regulatory organizations like the Financial Industry Regulatory Authority (FINRA). The Securities and Exchange Commission (SEC) regulates securities on the federal level. Other instruments related to securities, such as futures and some derivatives, are regulated by the Commodity Futures Trading Commission (CFTC).
psychology
Summary 13.1 What Is Industrial and Organizational Psychology? The field of I-O psychology had its birth in industrial psychology and the use of psychological concepts to aid in personnel selection. However, with research such as the Hawthorne study, it was found that productivity was affected more by human interaction and not physical factors; the field of industrial psychology expanded to include organizational psychology. Both WWI and WWII had a strong influence on the development of an expansion of industrial psychology in the United States and elsewhere: The tasks the psychologists were assigned led to development of tests and research in how the psychological concepts could assist industry and other areas. This movement aided in expanding industrial psychology to include organizational psychology. 13.2 Industrial Psychology: Selecting and Evaluating Employees Industrial psychology studies the attributes of jobs, applicants of those jobs, and methods for assessing fit to a job. These procedures include job analysis, applicant testing, and interviews. It also studies and puts into place procedures for the orientation of new employees and ongoing training of employees. The process of hiring employees can be vulnerable to bias, which is illegal, and industrial psychologists must develop methods for adhering to the law in hiring. Performance appraisal systems are an active area of research and practice in industrial psychology. 13.3 Organizational Psychology: The Social Dimension of Work Organizational psychology is concerned with the effects of interactions among people in the workplace on the employees themselves and on organizational productivity. Job satisfaction and its determinants and outcomes are a major focus of organizational psychology research and practice. Organizational psychologists have also studied the effects of management styles and leadership styles on productivity. In addition to the employees and management, organizational psychology also looks at the organizational culture and how that might affect productivity. One aspect of organization culture is the prevention and addressing of sexual and other forms of harassment in the workplace. Sexual harassment includes language, behavior, or displays that create a hostile environment; it also includes sexual favors requested in exchange for workplace rewards (i.e., quid pro quo). Industrial-organizational psychology has conducted extensive research on the triggers and causes of workplace violence and safety. This enables the organization to establish procedures that can identify these triggers before they become a problem. 13.4 Human Factors Psychology and Workplace Design Human factors psychology, or ergonomics, studies the interface between workers and their machines and physical environments. Human factors psychologists specifically seek to design machines to better support the workers using them. Psychologists may be involved in design of work tools such as software, displays, or machines from the beginning of the design process or during the testing an already developed product. Human factor psychologists are also involved in the development of best design recommendations and regulations. One important aspect of human factors psychology is enhancing worker safety. Human factors research involves efforts to understand and improve interactions between technology systems and their human operators. Human–software interactions are a large sector of this research.
Chapter Outline 13.1 What Is Industrial and Organizational Psychology? 13.2 Industrial Psychology: Selecting and Evaluating Employees 13.3 Organizational Psychology: The Social Dimension of Work 13.4 Human Factors Psychology and Workplace Design Introduction In July 2012, Yahoo!, one of the largest and oldest web companies, announced the appointment of Marissa Mayer as CEO. Yahoo! had struggled to define itself and excel in the industry for several years, and the appointment of Mayer, a top Google executive, made big news. Among her many decisions, in February 2013, Mayer announced that employees would no longer be allowed to telecommute. Telecommuting is representative of many management innovations that have been made in recent years, largely by tech companies. Telecommuting reflects a belief on the part of companies that employees are responsible, self-motivating, and perhaps work best when they are left alone. It also has an impact on work–family balance, though which way is yet unclear. And telecommuting reflects the more general trend of increasing overlap between workers’ time spent on the job and time spent off the job . The reversal of this policy at Yahoo! brought controversy and a lot of questions about what it meant. Mayer has stayed largely quiet on her reasoning behind the decision, except to say that it was meant to better the company. She finally addressed her decision briefly at the 2013 Great Place to Work conference (Tkaczyk, 2013) by saying, among other things, that while “people are more productive when they're alone, they're more collaborative and innovative when they're together.” Interestingly, shortly after the Yahoo! change, consumer electronics retailer Best Buy also eliminated telecommuting as an option for their employees. Will the change make Yahoo! more innovative or more productive? How has the change affected employees at the company, particularly working parents and those taking care of elderly relatives? Was the change introduced in the most effective way? These are questions that are commonly studied by a branch of psychology called industrial and organizational psychology.
[ { "answer": { "ans_choice": 2, "ans_text": "Walter Dill Scott" }, "bloom": null, "hl_context": "<hl> Scott was one of the first psychologists to apply psychology to advertising , management , and personnel selection . <hl> In 1903 , Scott published two books : The Theory of Advertising and Psychology of Advertising . They are the first books to describe the use of psychology in the business world . By 1911 he published two more books , Influencing Men in Business and Increasing Human Efficiency in Business . In 1916 a newly formed division in the Carnegie Institute of Technology hired Scott to conduct applied research on employee selection ( Katzell & Austin , 1992 ) .", "hl_sentences": "Scott was one of the first psychologists to apply psychology to advertising , management , and personnel selection .", "question": { "cloze_format": "___ was the first psychologist to use psychology in advertising.", "normal_format": "Who was the first psychologist to use psychology in advertising?", "question_choices": [ "Hugo Münsterberg", "Elton Mayo", "Walter Dill Scott", "Walter Bingham" ], "question_id": "fs-idm14004480", "question_text": "Who was the first psychologist to use psychology in advertising?" }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 2, "ans_text": "Army Beta" }, "bloom": null, "hl_context": "The involvement of the United States in World War I in April 1917 catalyzed the participation in the military effort of psychologists working in this area . At that time Yerkes was the president of the 25 - year-old American Psychological Association ( APA ) . The APA is a professional association in the United States for clinical and research psychologists . Today the APA performs a number of functions including holding conferences , accrediting university degree programs , and publishing scientific journals . Yerkes organized a group under the Surgeon General ’ s Office ( SGO ) that developed methods for screening and selecting enlisted men . They developed the Army Alpha test to measure mental abilities . <hl> The Army Beta test was a non-verbal form of the test that was administered to illiterate and non-English-speaking draftees . <hl> Scott and Bingham organized a group under the Adjutant General ’ s Office ( AGO ) with the goal to develop selection methods for officers . They created a catalogue of occupational needs for the Army , essentially a job-description system and a system of performance ratings and occupational skill tests for officers ( Katzell & Austin , 1992 ) .", "hl_sentences": "The Army Beta test was a non-verbal form of the test that was administered to illiterate and non-English-speaking draftees .", "question": { "cloze_format": "___ was designed for the Army for recruits who were not fluent in English.", "normal_format": "Which test designed for the Army was used for recruits who were not fluent in English?", "question_choices": [ "Army Personality", "Army Alpha", "Army Beta", "Army Intelligence" ], "question_id": "fs-idm136819632", "question_text": "Which test designed for the Army was used for recruits who were not fluent in English?" }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 1, "ans_text": "organizational psychology" }, "bloom": null, "hl_context": "<hl> Organizational psychology is the second major branch of study and practice within the discipline of industrial and organizational psychology . <hl> <hl> In organizational psychology , the focus is on social interactions and their effect on the individual and on the functioning of the organization . <hl> <hl> In this section , you will learn about the work organizational psychologists have done to understand job satisfaction , different styles of management , different styles of leadership , organizational culture , and teamwork . <hl>", "hl_sentences": "Organizational psychology is the second major branch of study and practice within the discipline of industrial and organizational psychology . In organizational psychology , the focus is on social interactions and their effect on the individual and on the functioning of the organization . In this section , you will learn about the work organizational psychologists have done to understand job satisfaction , different styles of management , different styles of leadership , organizational culture , and teamwork .", "question": { "cloze_format": "___ is the area of I-O psychology that measures job satisfaction.", "normal_format": "Which area of I-O psychology measures job satisfaction?", "question_choices": [ "industrial psychology", "organizational psychology", "human factors psychology", "advertising psychology" ], "question_id": "fs-idm127451408", "question_text": "Which area of I-O psychology measures job satisfaction?" }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 3, "ans_text": "The attention of researchers on subjects causes the effect the experimenter is looking for." }, "bloom": null, "hl_context": "<hl> Analysis of the findings by later researchers led to the term the Hawthorne effect , which describes the increase in performance of individuals who are noticed , watched , and paid attention to by researchers or supervisors Figure 13.5 ) . <hl> What the original researchers found was that any change in a variable , such as lighting levels , led to an improvement in productivity ; this was true even when the change was negative , such as a return to poor lighting . The effect faded when the attention faded ( Roethlisberg & Dickson , 1939 ) . The Hawthorne-effect concept endures today as an important experimental consideration in many fields and a factor that has to be controlled for in an experiment . <hl> In other words , an experimental treatment of some kind may produce an effect simply because it involves greater attention of the researchers on the participants ( McCarney et al . , 2007 ) . <hl>", "hl_sentences": "Analysis of the findings by later researchers led to the term the Hawthorne effect , which describes the increase in performance of individuals who are noticed , watched , and paid attention to by researchers or supervisors Figure 13.5 ) . In other words , an experimental treatment of some kind may produce an effect simply because it involves greater attention of the researchers on the participants ( McCarney et al . , 2007 ) .", "question": { "cloze_format": "___ best describes the Hawthorne effect.", "normal_format": "Which statement best describes the Hawthorne effect?", "question_choices": [ "Giving workers rest periods seems like it should decrease productivity, but it actually increases productivity.", "Social relations among workers have a greater effect on productivity than physical environment.", "Changes in light levels improve working conditions and therefore increase productivity.", "The attention of researchers on subjects causes the effect the experimenter is looking for." ], "question_id": "fs-idm147412752", "question_text": "Which statement best describes the Hawthorne effect?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 1, "ans_text": "Which state were you born in?" }, "bloom": null, "hl_context": "Some hiring criteria may be related to a particular group an applicant belongs to and not individual abilities . Unless membership in that group directly affects potential job performance , a decision based on group membership is discriminatory ( Figure 13.10 ) . <hl> To combat hiring discrimination , in the United States there are numerous city , state , and federal laws that prevent hiring based on various group-membership criteria . <hl> For example , did you know it is illegal for a potential employer to ask your age in an interview ? Did you know that an employer cannot ask you whether you are married , a U . S . citizen , have disabilities , or what your race or religion is ? <hl> They cannot even ask questions that might shed some light on these attributes , such as where you were born or who you live with . <hl> These are only a few of the restrictions that are in place to prevent discrimination in hiring . In the United States , federal anti-discrimination laws are administered by the U . S . Equal Employment Opportunity Commission ( EEOC ) .", "hl_sentences": "To combat hiring discrimination , in the United States there are numerous city , state , and federal laws that prevent hiring based on various group-membership criteria . They cannot even ask questions that might shed some light on these attributes , such as where you were born or who you live with .", "question": { "cloze_format": "It is illegal to ask in a job interview in the United States that ___.", "normal_format": "Which of the following questions is illegal to ask in a job interview in the United States?", "question_choices": [ "Which university did you attend?", "Which state were you born in?", "Do you have a commercial driver’s license?", "What salary would you expect for this position?" ], "question_id": "fs-idm150172160", "question_text": "Which of the following questions is illegal to ask in a job interview in the United States?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 0, "ans_text": "aspiration" }, "bloom": null, "hl_context": "The United States Department of Labor maintains a database of previously compiled job analyses for different jobs and occupations . This allows the I-O psychologist to access previous analyses for nearly any type of occupation . This system is called O * Net ( accessible at www.online.onetcenter.org ) . <hl> The site is open and you can see the KSAs that are listed for your own position or one you might be curious about . <hl> <hl> Each occupation lists the tasks , knowledge , skills , abilities , work context , work activities , education requirements , interests , personality requirements , and work styles that are deemed necessary for success in that position . <hl> You can also see data on average earnings and projected job growth in that industry . Link to Learning When you read job advertisements , do you ever wonder how the company comes up with the job description ? Often , this is done with the help of I-O psychologists . There are two related but different approaches to job analysis — you may be familiar with the results of each as they often appear on the same job advertisement . The first approach is task-oriented and lists in detail the tasks that will be performed for the job . Each task is typically rated on scales for how frequently it is performed , how difficult it is , and how important it is to the job . The second approach is worker-oriented . This approach describes the characteristics required of the worker to successfully perform the job . This second approach has been called job specification ( Dierdorff & Wilson , 2003 ) . <hl> For job specification , the knowledge , skills , and abilities ( KSAs ) that the job requires are identified . <hl>", "hl_sentences": "The site is open and you can see the KSAs that are listed for your own position or one you might be curious about . Each occupation lists the tasks , knowledge , skills , abilities , work context , work activities , education requirements , interests , personality requirements , and work styles that are deemed necessary for success in that position . For job specification , the knowledge , skills , and abilities ( KSAs ) that the job requires are identified .", "question": { "cloze_format": "___ is not a part of KSAs.", "normal_format": "Which of the following items is not a part of KSAs? ", "question_choices": [ "aspiration", "knowledge", "skill", "other abilities" ], "question_id": "fs-idp37339008", "question_text": "Which of the following items is not a part of KSAs?" }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 2, "ans_text": "U.S. Equal Employment Opportunity Commission" }, "bloom": null, "hl_context": "The U . S . Equal Employment Opportunity Commission ( EEOC ) The U . S . <hl> Equal Employment Opportunity Commission ( EEOC ) is responsible for enforcing federal laws that make it illegal to discriminate against a job applicant or an employee because of the person's race , color , religion , sex ( including pregnancy ) , national origin , age ( 40 or older ) , disability , or genetic information . <hl> Figure 13.11 provides some of the legal language from laws that have been passed to prevent discrimination . Some hiring criteria may be related to a particular group an applicant belongs to and not individual abilities . Unless membership in that group directly affects potential job performance , a decision based on group membership is discriminatory ( Figure 13.10 ) . To combat hiring discrimination , in the United States there are numerous city , state , and federal laws that prevent hiring based on various group-membership criteria . For example , did you know it is illegal for a potential employer to ask your age in an interview ? Did you know that an employer cannot ask you whether you are married , a U . S . citizen , have disabilities , or what your race or religion is ? They cannot even ask questions that might shed some light on these attributes , such as where you were born or who you live with . These are only a few of the restrictions that are in place to prevent discrimination in hiring . <hl> In the United States , federal anti-discrimination laws are administered by the U . S . <hl> Equal Employment Opportunity Commission ( EEOC ) .", "hl_sentences": "Equal Employment Opportunity Commission ( EEOC ) is responsible for enforcing federal laws that make it illegal to discriminate against a job applicant or an employee because of the person's race , color , religion , sex ( including pregnancy ) , national origin , age ( 40 or older ) , disability , or genetic information . In the United States , federal anti-discrimination laws are administered by the U . S .", "question": { "cloze_format": "____ is responsible for enforcing federal laws that make it illegal to discriminate against a job applicant.", "normal_format": "Who is responsible for enforcing federal laws that make it illegal to discriminate against a job applicant?", "question_choices": [ "Americans with Disabilities Act", "Supreme Court of the United States", "U.S. Equal Employment Opportunity Commission", "Society for Industrial and Organizational Psychology" ], "question_id": "fs-idm113397808", "question_text": "Who is responsible for enforcing federal laws that make it illegal to discriminate against a job applicant?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 0, "ans_text": "surgical team" }, "bloom": null, "hl_context": "There are three basic types of teams : problem resolution teams , creative teams , and tactical teams . Problem resolution teams are created for the purpose of solving a particular problem or issue ; for example , the diagnostic teams at the Centers for Disease Control . Creative teams are used to develop innovative possibilities or solutions ; for example , design teams for car manufacturers create new vehicle models . <hl> Tactical teams are used to execute a well-defined plan or objective , such as a police or FBI SWAT team handling a hostage situation ( Larson & LaFasto , 1989 ) . <hl> One area of active research involves a fourth kind of team — the virtual team ; these studies examine how groups of geographically disparate people brought together using digital communications technology function ( Powell , Piccoli , & Ives , 2004 ) . Virtual teams are more common due to the growing globalization of organizations and the use of consulting and partnerships facilitated by digital communication .", "hl_sentences": "Tactical teams are used to execute a well-defined plan or objective , such as a police or FBI SWAT team handling a hostage situation ( Larson & LaFasto , 1989 ) .", "question": { "cloze_format": "A ________ is an example of a tactical team.", "normal_format": "What is an example of a tactical team?", "question_choices": [ "surgical team", "car design team", "budget committee", "sports team" ], "question_id": "fs-idp21526464", "question_text": "A ________ is an example of a tactical team." }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 2, "ans_text": "keystroke monitoring" }, "bloom": null, "hl_context": "A significant portion of I-O research focuses on management and human relations . Douglas McGregor ( 1960 ) combined scientific management ( a theory of management that analyzes and synthesizes workflows with the main objective of improving economic efficiency , especially labor productivity ) and human relations into the notion of leadership behavior . His theory lays out two different styles called Theory X and Theory Y . In the Theory X approach to management , managers assume that most people dislike work and are not innately self-directed . <hl> Theory X managers perceive employees as people who prefer to be led and told which tasks to perform and when . <hl> <hl> Their employees have to be watched carefully to be sure that they work hard enough to fulfill the organization ’ s goals . <hl> Theory X workplaces will often have employees punch a clock when arriving and leaving the workplace : Tardiness is punished . Supervisors , not employees , determine whether an employee needs to stay late , and even this decision would require someone higher up in the command chain to approve the extra hours . Theory X supervisors will ignore employees ’ suggestions for improved efficiency and reprimand employees for speaking out of order . These supervisors blame efficiency failures on individual employees rather than the systems or policies in place . Managerial goals are achieved through a system of punishments and threats rather than enticements and rewards . Managers are suspicious of employees ’ motivations and always suspect selfish motivations for their behavior at work ( e . g . , being paid is their sole motivation for working ) .", "hl_sentences": "Theory X managers perceive employees as people who prefer to be led and told which tasks to perform and when . Their employees have to be watched carefully to be sure that they work hard enough to fulfill the organization ’ s goals .", "question": { "cloze_format": "The practice that is an example of Theory X management is ___.", "normal_format": "Which practice is an example of Theory X management?", "question_choices": [ "telecommuting", "flextime", "keystroke monitoring", "team meetings" ], "question_id": "fs-idm132926544", "question_text": "Which practice is an example of Theory X management?" }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 0, "ans_text": "teams appear to work better than they do" }, "bloom": null, "hl_context": "Why do some teams work well while others do not ? There are many contributing factors . For example , teams can mask team members that are not working ( i . e . , social loafing ) . Teams can be inefficient due to poor communication ; they can have poor decision-making skills due to conformity effects ; and , they can have conflict within the group . <hl> The popularity of teams may in part result from the team halo effect : Teams are given credit for their successes . <hl> <hl> but individuals within a team are blamed for team failures ( Naquin & Tynan , 2003 ) . <hl> One aspect of team diversity is their gender mix . Researchers have explored whether gender mix has an effect on team performance . On the one hand , diversity can introduce communication and interpersonal-relationship problems that hinder performance , but on the other hand diversity can also increase the team ’ s skill set , which may include skills that can actually improve team member interactions . Hoogendoorn , Oosterbeek , & van Praag ( 2013 ) studied project teams in a university business school in which the gender mix of the teams was manipulated . They found that gender-balanced teams ( i . e . , nearly equal numbers of men and women ) performed better , as measured by sales and profits , than predominantly male teams . The study did not have enough data to determine the relative performance of female dominated teams . The study was unsuccessful in identifying which mechanism ( interpersonal relationships , learning , or skills mixes ) accounted for performance improvement .", "hl_sentences": "The popularity of teams may in part result from the team halo effect : Teams are given credit for their successes . but individuals within a team are blamed for team failures ( Naquin & Tynan , 2003 ) .", "question": { "cloze_format": "___ is one effect of the team halo effect.", "normal_format": "Which is one effect of the team halo effect?", "question_choices": [ "teams appear to work better than they do", "teams never fail", "teams lead to greater job satisfaction", "teams boost productivity" ], "question_id": "fs-idm11249824", "question_text": "Which is one effect of the team halo effect?" }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 3, "ans_text": "work content" }, "bloom": null, "hl_context": "<hl> Research has suggested that the work-content factor , which includes variety , difficulty level , and role clarity of the job , is the most strongly predictive factor of overall job satisfaction ( Saari & Judge , 2004 ) . <hl> In contrast , there is only a weak correlation between pay level and job satisfaction ( Judge , Piccolo , Podsakoff , Shaw , & Rich , 2010 ) . Judge et al . ( 2010 ) suggest that individuals adjust or adapt to higher pay levels : Higher pay no longer provides the satisfaction the individual may have initially felt when her salary increased .", "hl_sentences": "Research has suggested that the work-content factor , which includes variety , difficulty level , and role clarity of the job , is the most strongly predictive factor of overall job satisfaction ( Saari & Judge , 2004 ) .", "question": { "cloze_format": "___ is the most strongly predictive factor of overall job satisfaction.", "normal_format": "Which of the following is the most strongly predictive factor of overall job satisfaction?", "question_choices": [ "financial rewards", "personality", "autonomy", "work content" ], "question_id": "fs-idm18004704", "question_text": "Which of the following is the most strongly predictive factor of overall job satisfaction?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 1, "ans_text": "quid pro quo" }, "bloom": null, "hl_context": "One form of sexual harassment is called quid pro quo . Quid pro quo means you give something to get something , and it refers to a situation in which organizational rewards are offered in exchange for sexual favors . <hl> Quid pro quo harassment is often between an employee and a person with greater power in the organization . <hl> <hl> For example , a supervisor might request an action , such as a kiss or a touch , in exchange for a promotion , a positive performance review , or a pay raise . <hl> Another form of sexual harassment is the threat of withholding a reward if a sexual request is refused . Hostile environment sexual harassment is another type of workplace harassment . In this situation , an employee experiences conditions in the workplace that are considered hostile or intimidating . For example , a work environment that allows offensive language or jokes or displays sexually explicit images . Isolated occurrences of these events do not constitute harassment , but a pattern of repeated occurrences does . In addition to violating organizational policies against sexual harassment , these forms of harassment are illegal . <hl> Title VII of the Civil Rights Act of 1964 makes it illegal to treat individuals unfavorably because of their race or color of their skin : An employer cannot discriminate based on skin color , hair texture , or other immutable characteristics , which are traits of an individual that are fundamental to her identity , in hiring , benefits , promotions , or termination of employees . <hl> The Pregnancy Discrimination Act of 1978 amends the Civil Rights Act ; it prohibits job ( e . g . , employment , pay , and termination ) discrimination of a woman because she is pregnant as long as she can perform the work required .", "hl_sentences": "Quid pro quo harassment is often between an employee and a person with greater power in the organization . For example , a supervisor might request an action , such as a kiss or a touch , in exchange for a promotion , a positive performance review , or a pay raise . Title VII of the Civil Rights Act of 1964 makes it illegal to treat individuals unfavorably because of their race or color of their skin : An employer cannot discriminate based on skin color , hair texture , or other immutable characteristics , which are traits of an individual that are fundamental to her identity , in hiring , benefits , promotions , or termination of employees .", "question": { "cloze_format": "When a supervisor offers a work-related reward in exchange for a sexual favor it is called ___.", "normal_format": "What is the name for what occurs when a supervisor offers a work-related reward in exchange for a sexual favor?", "question_choices": [ "hiring bias", "quid pro quo", "hostile work environment", "immutable characteristics" ], "question_id": "fs-idm83051936", "question_text": "What is the name for what occurs when a supervisor offers a work-related reward in exchange for a sexual favor?" }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 0, "ans_text": "height of the chair" }, "bloom": null, "hl_context": "Industrial and organizational psychologists work in four main contexts : academia , government , consulting firms , and business . Most I-O psychologists have a master ’ s or doctorate degree . The field of I-O psychology can be divided into three broad areas ( Figure 13.2 and Figure 13.3 ): industrial , organizational , and human factors . Industrial psychology is concerned with describing job requirements and assessing individuals for their ability to meet those requirements . In addition , once employees are hired , industrial psychology studies and develops ways to train , evaluate , and respond to those evaluations . As a consequence of its concern for candidate characteristics , industrial psychology must also consider issues of legality regarding discrimination in hiring . Organizational psychology is a discipline interested in how the relationships among employees affect those employees and the performance of a business . This includes studying worker satisfaction , motivation , and commitment . This field also studies management , leadership , and organizational culture , as well as how an organization ’ s structures , management and leadership styles , social norms , and role expectations affect individual behavior . As a result of its interest in worker wellbeing and relationships , organizational psychology also considers the subjects of harassment , including sexual harassment , and workplace violence . <hl> Human factors psychology is the study of how workers interact with the tools of work and how to design those tools to optimize workers ’ productivity , safety , and health . <hl> <hl> These studies can involve interactions as straightforward as the fit of a desk , chair , and computer to a human having to sit on the chair at the desk using the computer for several hours each day . <hl> They can also include the examination of how humans interact with complex displays and their ability to interpret them accurately and quickly . In Europe , this field is referred to as ergonomics .", "hl_sentences": "Human factors psychology is the study of how workers interact with the tools of work and how to design those tools to optimize workers ’ productivity , safety , and health . These studies can involve interactions as straightforward as the fit of a desk , chair , and computer to a human having to sit on the chair at the desk using the computer for several hours each day .", "question": { "cloze_format": "The aspect of an office workstation that a human factors psychologist would be concerned about is the ___ .", "normal_format": "What aspect of an office workstation would a human factors psychologist be concerned about?", "question_choices": [ "height of the chair", "closeness to the supervisor", "frequency of coworker visits", "presence of an offensive sign" ], "question_id": "fs-idp59921824", "question_text": "What aspect of an office workstation would a human factors psychologist be concerned about?" }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 1, "ans_text": "cognitive engineering" }, "bloom": null, "hl_context": "Human factors psychology ( or ergonomics , a term that is favored in Europe ) is the third subject area within industrial and organizational psychology . This field is concerned with the integration of the human-machine interface in the workplace , through design , and specifically with researching and designing machines that fit human requirements . <hl> The integration may be physical or cognitive , or a combination of both . <hl> Anyone who needs to be convinced that the field is necessary need only try to operate an unfamiliar television remote control or use a new piece of software for the first time . <hl> Whereas the two other areas of I-O psychology focus on the interface between the worker and team , group , or organization , human factors psychology focuses on the individual worker ’ s interaction with a machine , work station , information displays , and the local environment , such as lighting . <hl> <hl> In the United States , human factors psychology has origins in both psychology and engineering ; this is reflected in the early contributions of Lillian Gilbreth ( psychologist and engineer ) and her husband Frank Gilbreth ( engineer ) . <hl>", "hl_sentences": "The integration may be physical or cognitive , or a combination of both . Whereas the two other areas of I-O psychology focus on the interface between the worker and team , group , or organization , human factors psychology focuses on the individual worker ’ s interaction with a machine , work station , information displays , and the local environment , such as lighting . In the United States , human factors psychology has origins in both psychology and engineering ; this is reflected in the early contributions of Lillian Gilbreth ( psychologist and engineer ) and her husband Frank Gilbreth ( engineer ) .", "question": { "cloze_format": "A human factors psychologist who studied how a worker interacted with a search engine would be researching in the area of ________.", "normal_format": "In which area would a human factors psychologist who studied how a worker interacted with a search engine be researching?", "question_choices": [ "attention", "cognitive engineering", "job satisfaction", "management" ], "question_id": "fs-idm625552", "question_text": "A human factors psychologist who studied how a worker interacted with a search engine would be researching in the area of ________." }, "references_are_paraphrase": null } ]
13
13.1 What Is Industrial and Organizational Psychology? Learning Objectives By the end of this section, you will be able to: Understand the scope of study in the field of industrial and organizational psychology Describe the history of industrial and organizational psychology In 2012, people who worked in the United States spent an average of 56.4 hours per week working (Bureau of Labor Statistics—U.S. Department of Labor, 2013). Sleeping was the only other activity they spent more time on with an average of 61.2 hours per week. The workday is a significant portion of workers’ time and energy. It impacts their lives and their family’s lives in positive and negative physical and psychological ways. Industrial and organizational (I-O) psychology is a branch of psychology that studies how human behavior and psychology affect work and how they are affected by work. Industrial and organizational psychologists work in four main contexts: academia, government, consulting firms, and business. Most I-O psychologists have a master’s or doctorate degree. The field of I-O psychology can be divided into three broad areas ( Figure 13.2 and Figure 13.3 ): industrial, organizational, and human factors. Industrial psychology is concerned with describing job requirements and assessing individuals for their ability to meet those requirements. In addition, once employees are hired, industrial psychology studies and develops ways to train, evaluate, and respond to those evaluations. As a consequence of its concern for candidate characteristics, industrial psychology must also consider issues of legality regarding discrimination in hiring. Organizational psychology is a discipline interested in how the relationships among employees affect those employees and the performance of a business. This includes studying worker satisfaction, motivation, and commitment. This field also studies management, leadership, and organizational culture, as well as how an organization’s structures, management and leadership styles, social norms, and role expectations affect individual behavior. As a result of its interest in worker wellbeing and relationships, organizational psychology also considers the subjects of harassment, including sexual harassment, and workplace violence. Human factors psychology is the study of how workers interact with the tools of work and how to design those tools to optimize workers’ productivity, safety, and health. These studies can involve interactions as straightforward as the fit of a desk, chair, and computer to a human having to sit on the chair at the desk using the computer for several hours each day. They can also include the examination of how humans interact with complex displays and their ability to interpret them accurately and quickly. In Europe, this field is referred to as ergonomics. Link to Learning Find out what I-O psychologists do on the Society for Industrial and Organizational Psychology (SIOP) website—a professional organization for people working in the discipline. This site also offers several I-O psychologist profiles. The Historical Development of Industrial and Organizational Psychology Industrial and organizational psychology had its origins in the early 20th century. Several influential early psychologists studied issues that today would be categorized as industrial psychology: James Cattell (1860–1944) at Columbia, Hugo Münsterberg (1863–1916) at Harvard, Walter Dill Scott (1869–1955) at Northwestern, Robert Yerkes (1876–1956) and Walter Bingham (1880–1952) at Dartmouth, and Lillian Gilbreth (1878–1972) at Purdue. Cattell, Münsterberg, and Scott had been students of Wilhelm Wundt, the father of experimental psychology. Some of these researchers had been involved in work in the area of industrial psychology before World War I. Cattell’s contribution to industrial psychology is largely reflected in his founding of a psychological consulting company, which is still operating today called the Psychological Corporation, and in the accomplishments of students at Columbia in the area of industrial psychology. In 1913, Münsterberg published Psychology and Industrial Efficiency , which covered topics such as employee selection, employee training, and effective advertising. Scott was one of the first psychologists to apply psychology to advertising, management, and personnel selection. In 1903, Scott published two books: The Theory of Advertising and Psychology of Advertising . They are the first books to describe the use of psychology in the business world. By 1911 he published two more books, Influencing Men in Business and Increasing Human Efficiency in Business . In 1916 a newly formed division in the Carnegie Institute of Technology hired Scott to conduct applied research on employee selection (Katzell & Austin, 1992). The focus of all this research was in what we now know as industrial psychology; it was only later in the century that the field of organizational psychology developed as an experimental science (Katzell & Austin, 1992). In addition to their academic positions, these researchers also worked directly for businesses as consultants. The involvement of the United States in World War I in April 1917 catalyzed the participation in the military effort of psychologists working in this area. At that time Yerkes was the president of the 25-year-old American Psychological Association (APA) . The APA is a professional association in the United States for clinical and research psychologists. Today the APA performs a number of functions including holding conferences, accrediting university degree programs, and publishing scientific journals. Yerkes organized a group under the Surgeon General’s Office (SGO) that developed methods for screening and selecting enlisted men. They developed the Army Alpha test to measure mental abilities. The Army Beta test was a non-verbal form of the test that was administered to illiterate and non-English-speaking draftees. Scott and Bingham organized a group under the Adjutant General’s Office (AGO) with the goal to develop selection methods for officers. They created a catalogue of occupational needs for the Army, essentially a job-description system and a system of performance ratings and occupational skill tests for officers (Katzell & Austin, 1992). After the war, work on personnel selection continued. For example, Millicent Pond, who received a PhD from Yale University, worked at several businesses and was director of employment test research at Scoville Manufacturing Company. She researched the selection of factory workers, comparing the results of pre-employment tests with various indicators of job performance. These studies were published in a series of research articles in the Journal of Personnel Research in the late 1920s (Vinchur & Koppes, 2014). From 1929 to 1932 Elton Mayo (1880–1949) and his colleagues began a series of studies at a plant near Chicago, Western Electric’s Hawthorne Works ( Figure 13.4 ). This long-term project took industrial psychology beyond just employee selection and placement to a study of more complex problems of interpersonal relations, motivation, and organizational dynamics. These studies mark the origin of organizational psychology. They began as research into the effects of the physical work environment (e.g., level of lighting in a factory), but the researchers found that the psychological and social factors in the factory were of more interest than the physical factors. These studies also examined how human interaction factors, such as supervisorial style, enhanced or decreased productivity. Analysis of the findings by later researchers led to the term the Hawthorne effect , which describes the increase in performance of individuals who are noticed, watched, and paid attention to by researchers or supervisors Figure 13.5 ). What the original researchers found was that any change in a variable, such as lighting levels, led to an improvement in productivity; this was true even when the change was negative, such as a return to poor lighting. The effect faded when the attention faded (Roethlisberg & Dickson, 1939). The Hawthorne-effect concept endures today as an important experimental consideration in many fields and a factor that has to be controlled for in an experiment. In other words, an experimental treatment of some kind may produce an effect simply because it involves greater attention of the researchers on the participants (McCarney et al., 2007). Link to Learning Watch this video to hear first-hand accounts of the original Hawthorne studies from those who participated in the research. In the 1930s, researchers began to study employees’ feelings about their jobs. Kurt Lewin also conducted research on the effects of various leadership styles, team structure, and team dynamics (Katzell & Austin, 1992). Lewin is considered the founder of social psychology and much of his work and that of his students produced results that had important influences in organizational psychology. Lewin and his students’ research included an important early study that used children to study the effect of leadership style on aggression, group dynamics, and satisfaction (Lewin, Lippitt, & White, 1939). Lewin was also responsible for coining the term group dynamics , and he was involved in studies of group interactions, cooperation, competition, and communication that bear on organizational psychology. Parallel to these studies in industrial and organizational psychology, the field of human factors psychology was also developing. Frederick Taylor was an engineer who saw that if one could redesign the workplace there would be an increase in both output for the company and wages for the workers. In 1911 he put forward his theory in a book titled, The Principles of Scientific Management ( Figure 13.6 ). His book examines management styles, personnel selection and training, as well as the work itself, using time and motion studies. One of the examples of Taylor’s theory in action involved workers handling heavy iron ingots. Taylor showed that the workers could be more productive by taking work rests. This method of rest increased worker productivity from 12.5 to 47.0 tons moved per day with less reported fatigue as well as increased wages for the workers who were paid by the ton. At the same time, the company’s cost was reduced from 9.2 cents to 3.9 cents per ton. Despite these increases in productivity, Taylor’s theory received a great deal of criticism at the time because it was believed that it would exploit workers and reduce the number of workers needed. Also controversial was the underlying concept that only a manager could determine the most efficient method of working, and that while at work, a worker was incapable of this. Taylor’s theory was underpinned by the notion that a worker was fundamentally lazy and the goal of Taylor’s scientific management approach was to maximize productivity without much concern for worker well-being. His approach was criticized by unions and those sympathetic to workers (Van De Water, 1997). Gilbreth was another influential I-O psychologist who strove to find ways to increase productivity ( Figure 13.7 ). Using time and motion studies, Gilbreth and her husband, Frank, worked to make workers more efficient by reducing the number of motions required to perform a task. She not only applied these methods to industry but also to the home, office, shops, and other areas. She investigated employee fatigue and time management stress and found many employees were motivated by money and job satisfaction. In 1914, Gilbreth wrote the book title, The Psychology of Management: The Function of the Mind in Determining, Teaching, and Installing Methods of Least Waste , and she is known as the mother of modern management. Some of Gilbreth’s contributions are still in use today: you can thank her for the idea to put shelves inside on refrigerator doors, and she also came up with the concept of using a foot pedal to operate the lid of trash can (Gilbreth, 1914, 1998; Koppes, 1997; Lancaster, 2004). Gilbreth was the first woman to join the American Society of Mechanical Engineers in 1926, and in 1966 she was awarded the Hoover Medal of the American Society of Civil Engineers. Taylor and Gilbreth’s work improved productivity, but these innovations also improved the fit between technology and the human using it. The study of machine–human fit is known as ergonomics or human factors psychology. From WWII to Today World War II also drove the expansion of industrial psychology. Bingham was hired as the chief psychologist for the War Department (now the Department of Defense) and developed new systems for job selection, classification, training, ad performance review, plus methods for team development, morale change, and attitude change (Katzell & Austin, 1992). Other countries, such as Canada and the United Kingdom, likewise saw growth in I-O psychology during World War II (McMillan, Stevens, & Kelloway, 2009). In the years after the war, both industrial psychology and organizational psychology became areas of significant research effort. Concerns about the fairness of employment tests arose, and the ethnic and gender biases in various tests were evaluated with mixed results. In addition, a great deal of research went into studying job satisfaction and employee motivation (Katzell & Austin, 1992). Today, I-O psychology is a diverse and deep field of research and practice, as you will learn about in the rest of this chapter. The Society for Industrial and Organizational Psychology (SIOP) , a division of the APA, lists 8,000 members (SIOP, 2014) and the Bureau of Labor Statistics—U.S. Department of Labor (2013) has projected this profession will have the greatest growth of all job classifications in the 20 years following 2012. On average, a person with a master’s degree in industrial-organizational psychology will earn over $80,000 a year, while someone with a doctorate will earn over $110,000 a year (Khanna, Medsker, & Ginter, 2012). 13.2 Industrial Psychology: Selecting and Evaluating Employees Learning Objectives By the end of this section, you will be able to: Explain the aspects of employee selection Describe the kinds of job training Describe the approaches to and issues surrounding performance assessment The branch of I-O psychology known as industrial psychology focuses on identifying and matching persons to tasks within an organization. This involves job analysis , which means accurately describing the task or job. Then, organizations must identify the characteristics of applicants for a match to the job analysis. It also involves training employees from their first day on the job throughout their tenure within the organization, and appraising their performance along the way. Selecting Employees When you read job advertisements, do you ever wonder how the company comes up with the job description? Often, this is done with the help of I-O psychologists. There are two related but different approaches to job analysis—you may be familiar with the results of each as they often appear on the same job advertisement. The first approach is task-oriented and lists in detail the tasks that will be performed for the job. Each task is typically rated on scales for how frequently it is performed, how difficult it is, and how important it is to the job. The second approach is worker-oriented. This approach describes the characteristics required of the worker to successfully perform the job. This second approach has been called job specification (Dierdorff & Wilson, 2003). For job specification, the knowledge, skills, and abilities (KSAs) that the job requires are identified. Observation, surveys, and interviews are used to obtain the information required for both types of job analysis. It is possible to observe someone who is proficient in a position and analyze what skills are apparent. Another approach used is to interview people presently holding that position, their peers, and their supervisors to get a consensus of what they believe are the requirements of the job. How accurate and reliable is a job analysis? Research suggests that it can depend on the nature of the descriptions and the source for the job analysis. For example, Dierdorff & Wilson (2003) found that job analyses developed from descriptions provided by people holding the job themselves were the least reliable; however, they did not study or speculate why this was the case. The United States Department of Labor maintains a database of previously compiled job analyses for different jobs and occupations. This allows the I-O psychologist to access previous analyses for nearly any type of occupation. This system is called O*Net (accessible at www.online.onetcenter.org). The site is open and you can see the KSAs that are listed for your own position or one you might be curious about. Each occupation lists the tasks, knowledge, skills, abilities, work context, work activities, education requirements, interests, personality requirements, and work styles that are deemed necessary for success in that position. You can also see data on average earnings and projected job growth in that industry. Link to Learning The O*Net database describes the skills, knowledge, and education required for occupations, as well as what personality types and work styles are best suited to the role. See what it has to say about being a food server in a restaurant or an elementary school teacher or an industrial-organizational psychologist . Candidate Analysis and Testing Once a company identifies potential candidates for a position, the candidates’ knowledge, skills, and other abilities must be evaluated and compared with the job description. These evaluations can involve testing, an interview, and work samples or exercises. You learned about personality tests in the chapter on personality; in the I-O context, they are used to identify the personality characteristics of the candidate in an effort to match those to personality characteristics that would ensure good performance on the job. For example, a high rating of agreeableness might be desirable in a customer support position. However, it is not always clear how best to correlate personality characteristics with predictions of job performance. It might be that too high of a score on agreeableness is actually a hindrance in the customer support position. For example, if a customer has a misperception about a product or service, agreeing with their misperception will not ultimately lead to resolution of their complaint. Any use of personality tests should be accompanied by a verified assessment of what scores on the test correlate with good performance (Arthur, Woehr, & Graziano, 2001). Other types of tests that may be given to candidates include IQ tests, integrity tests, and physical tests, such as drug tests or physical fitness tests. What Do You Think? Using Cutoff Scores to Determine Job Selection Many positions require applicants to take tests as part of the selection process. These can include IQ tests, job-specific skills tests, or personality tests. The organization may set cutoff scores (i.e., a score below which a candidate will not move forward) for each test to determine whether the applicant moves on to the next stage. For example, there was a case of Robert Jordan, a 49-year-old college graduate who applied for a position with the police force in New London, Connecticut. As part of the selection process, Jordan took the Wonderlic Personnel Test (WPT), a test designed to measure cognitive ability. Jordan did not make it to the interview stage because his WPT score of 33, equivalent to an IQ score of 125 (100 is the average IQ score), was too high. The New London Police department policy is to not interview anyone who has a WPT score over 27 (equivalent to an IQ score over 104) because they believe anyone who scores higher would be bored with police work. The average score for police officers nationwide is the equivalent of an IQ score of 104 ( Jordan v. New London , 2000; ABC News, 2000). Jordan sued the police department alleging that his rejection was discrimination and his civil rights were violated because he was denied equal protection under the law. The 2nd U.S. Circuit Court of Appeals upheld a lower court’s decision that the city of New London did not discriminate against him because the same standards were applied to everyone who took the exam (The New York Times, 1999). What do you think? When might universal cutoff points make sense in a hiring decision, and when might they eliminate otherwise potentially strong employees? Interviews Most jobs for mid-size to large-size businesses in the United States require a personal interview as a step in the selection process. Because interviews are commonly used, they have been the subject of considerable research by industrial psychologists. Information derived from job analysis usually forms the basis for the types of questions asked. Interviews can provide a more dynamic source of information about the candidate than standard testing measures. Importantly, social factors and body language can influence the outcome of the interview. These include influences, such as the degree of similarity of the applicant to the interviewer and nonverbal behaviors, such as hand gestures, head nodding, and smiling (Bye, Horverak, Sandal, Sam, & Vivjer, 2014; Rakić, Steffens, & Mummendey, 2011). There are two types of interviews: unstructured and structured. In an unstructured interview, the interviewer may ask different questions of each different candidate. One candidate might be asked about her career goals, and another might be asked about his previous work experience. In an unstructured interview, the questions are often, though not always, unspecified beforehand. And in an unstructured interview the responses to questions asked are generally not scored using a standard system. In a structured interview, the interviewer asks the same questions of every candidate, the questions are prepared in advance, and the interviewer uses a standardized rating system for each response. With this approach, the interviewer can accurately compare two candidates’ interviews. In a meta-analysis of studies examining the effectiveness of various types of job interviews, McDaniel, Whetzel, Schmidt & Maurer (1994) found that structured interviews were more effective at predicting subsequent job performance of the job candidate. Everyday Connection Preparing for the Job Interview You might be wondering if psychology research can tell you how to succeed in a job interview . As you can imagine, most research is concerned with the employer’s interest in choosing the most appropriate candidate for the job, a goal that makes sense for the candidate too. But suppose you are not the only qualified candidate for the job; is there a way to increase your chances of being hired? A limited amount of research has addressed this question. As you might expect, nonverbal cues are important in an interview. Liden, Martin, & Parsons (1993) found that lack of eye contact and smiling on the part of the applicant led to lower applicant ratings. Studies of impression management on the part of an applicant have shown that self-promotion behaviors generally have a positive impact on interviewers (Gilmore & Ferris, 1989). Different personality types use different forms of impression management, for example extroverts use verbal self-promotion, and applicants high in agreeableness use non-verbal methods such as smiling and eye contact. Self-promotion was most consistently related with a positive outcome for the interview, particularly if it was related to the candidate’s person–job fit. However, it is possible to overdo self-promotion with experienced interviewers (Howard & Ferris, 1996). Barrick, Swider & Stewart (2010) examined the effect of first impressions during the rapport building that typically occurs before an interview begins. They found that initial judgments by interviewers during this period were related to job offers and that the judgments were about the candidate’s competence and not just likability. Levine and Feldman (2002) looked at the influence of several nonverbal behaviors in mock interviews on candidates’ likability and projections of competence. Likability was affected positively by greater smiling behavior. Interestingly, other behaviors affected likability differently depending on the gender of the applicant. Men who displayed higher eye contact were less likable; women were more likable when they made greater eye contact. However, for this study male applicants were interviewed by men and female applicants were interviewed by women. In a study carried out in a real setting, DeGroot & Gooty (2009) found that nonverbal cues affected interviewers’ assessments about candidates. They looked at visual cues, which can often be modified by the candidate and vocal (nonverbal) cues, which are more difficult to modify. They found that interviewer judgment was positively affected by visual and vocal cues of conscientiousness, visual and vocal cues of openness to experience, and vocal cues of extroversion. What is the take home message from the limited research that has been done? Learn to be aware of your behavior during an interview. You can do this by practicing and soliciting feedback from mock interviews. Pay attention to any nonverbal cues you are projecting and work at presenting nonverbal cures that project confidence and positive personality traits. And finally, pay attention to the first impression you are making as it may also have an impact in the interview. Training Training is an important element of success and performance in many jobs. Most jobs begin with an orientation period during which the new employee is provided information regarding the company history, policies, and administrative protocols such as time tracking, benefits, and reporting requirements. An important goal of orientation training is to educate the new employee about the organizational culture, the values, visions, hierarchies, norms and ways the company’s employees interact—essentially how the organization is run, how it operates, and how it makes decisions. There will also be training that is specific to the job the individual was hired to do, or training during the individual’s period of employment that teaches aspects of new duties, or how to use new physical or software tools. Much of these kinds of training will be formalized for the employee; for example, orientation training is often accomplished using software presentations, group presentations by members of the human resources department or with people in the new hire’s department ( Figure 13.8 ). Mentoring is a form of informal training in which an experienced employee guides the work of a new employee. In some situations, mentors will be formally assigned to a new employee, while in others a mentoring relationship may develop informally. Mentoring effects on the mentor and the employee being mentored, the protégé, have been studied in recent years. In a review of mentoring studies, Eby, Allen, Evans, Ng, & DuBois (2008) found significant but small effects of mentoring on performance (i.e., behavioral outcomes), motivation and satisfaction, and actual career outcomes. In a more detailed review, Allen, Eby, Poteet, Lentz, & Lima (2004) found that mentoring positively affected a protégé’s compensation and number of promotions compared with non-mentored employees. In addition, protégés were more satisfied with their careers and had greater job satisfaction. All of the effects were small but significant. Eby, Durley, Evans, & Ragins (2006) examined mentoring effects on the mentor and found that mentoring was associated with greater job satisfaction and organizational commitment. Gentry, Weber, & Sadri (2008) found that mentoring was positively related with performance ratings by supervisors. Allen, Lentz, & Day (2006) found in a comparison of mentors and non-mentors that mentoring led to greater reported salaries and promotions. Mentoring is recognized to be particularly important to the career success of women (McKeen & Bujaki, 2007) by creating connections to informal networks, adopting a style of interaction that male managers are comfortable with, and with overcoming discrimination in job promotions. Gender combinations in mentoring relationships are also an area of active study. Ragins & Cotton (1999) studied the effects of gender on the outcomes of mentoring relationships and found that protégés with a history of male mentors had significantly higher compensation especially for male protégés. The study found that female mentor–male protégé relationships were considerably rarer than the other gender combinations. In an examination of a large number of studies on the effectiveness of organizational training to meet its goals, Arthur, Bennett, Edens, and Bell (2003) found that training was, in fact, effective when measured by the immediate response of the employee to the training effort, evaluation of learning outcomes (e.g., a test at the end of the training), behavioral measurements of job activities by a supervisor, and results-based criteria (e.g., productivity or profits). The examined studies represented diverse forms of training including self-instruction, lecture and discussion, and computer assisted training. Evaluating Employees Industrial and organizational psychologists are typically involved in designing performance-appraisal systems for organizations. These systems are designed to evaluate whether each employee is performing her job satisfactorily. Industrial and organizational psychologists study, research, and implement ways to make work evaluations as fair and positive as possible; they also work to decrease the subjectivity involved with performance ratings. Fairly evaluated work helps employees do their jobs better, improves the likelihood of people being in the right jobs for their talents, maintains fairness, and identifies company and individual training needs. Performance appraisals are typically documented several times a year, often with a formal process and an annual face-to-face brief meeting between an employee and his supervisor. It is important that the original job analysis play a role in performance appraisal as well as any goals that have been set by the employee or by the employee and supervisor. The meeting is often used for the supervisor to communicate specific concerns about the employee’s performance and to positively reinforce elements of good performance. It may also be used to discuss specific performance rewards, such as a pay increase, or consequences of poor performance, such as a probationary period. Part of the function of performance appraisals for the organization is to document poor performance to bolster decisions to terminate an employee. Performance appraisals are becoming more complex processes within organizations and are often used to motivate employees to improve performance and expand their areas of competence, in addition to assessing their job performance. In this capacity, performance appraisals can be used to identify opportunities for training or whether a particular training program has been successful. One approach to performance appraisal is called 360-degree feedback appraisal ( Figure 13.9 ). In this system, the employee’s appraisal derives from a combination of ratings by supervisors, peers, employees supervised by the employee, and from the employee herself. Occasionally, outside observers may be used as well, such as customers. The purpose of 360-degree system is to give the employee (who may be a manager) and supervisor different perspectives of the employee’s job performance; the system should help employees make improvements through their own efforts or through training. The system is also used in a traditional performance-appraisal context, providing the supervisor with more information with which to make decisions about the employee’s position and compensation (Tornow, 1993a). Few studies have assessed the effectiveness of 360-degree methods, but Atkins and Wood (2002) found that the self and peer ratings were unreliable as an assessment of an employee’s performance and that even supervisors tended to underrate employees that gave themselves modest feedback ratings. However, a different perspective sees this variability in ratings as a positive in that it provides for greater learning on the part of the employees as they and their supervisor discuss the reasons for the discrepancies (Tornow, 1993b). In theory, performance appraisals should be an asset for an organization wishing to achieve its goals, and most employees will actually solicit feedback regarding their jobs if it is not offered (DeNisi & Kluger, 2000). However, in practice, many performance evaluations are disliked by organizations, employees, or both (Fletcher, 2001), and few of them have been adequately tested to see if they do in fact improve performance or motivate employees (DeNisi & Kluger, 2000). One of the reasons evaluations fail to accomplish their purpose in an organization is that performance appraisal systems are often used incorrectly or are of an inappropriate type for an organization’s particular culture (Schraeder, Becton, & Portis, 2007). An organization’s culture is how the organization is run, how it operates, and how it makes decisions. It is based on the collective values, hierarchies, and how individuals within the organization interact. Examining the effectiveness of performance appraisal systems in particular organizations and the effectiveness of training for the implementation of the performance appraisal system is an active area of research in industrial psychology (Fletcher, 2001). Bias and Protections in Hiring In an ideal hiring process, an organization would generate a job analysis that accurately reflects the requirements of the position, and it would accurately assess candidates’ KSAs to determine who the best individual is to carry out the job’s requirements. For many reasons, hiring decisions in the real world are often made based on factors other than matching a job analysis to KSAs. As mentioned earlier, interview rankings can be influenced by other factors: similarity to the interviewer (Bye, Horverak, Sandal, Sam, & Vijver, 2014) and the regional accent of the interviewee (Rakić, Steffens, & Mummendey 2011). A study by Agerström & Rooth (2011) examined hiring managers’ decisions to invite equally qualified normal-weight and obese job applicants to an interview. The decisions of the hiring managers were based on photographs of the two applicants. The study found that hiring managers that scored high on a test of negative associations with overweight people displayed a bias in favor of inviting the equally qualified normal-weight applicant but not inviting the obese applicant. The association test measures automatic or subconscious associations between an individual’s negative or positive values and, in this case, the body-weight attribute. A meta-analysis of experimental studies found that physical attractiveness benefited individuals in various job-related outcomes such as hiring, promotion, and performance review (Hosoda, Stone-Romero, & Coats, 2003). They also found that the strength of the benefit appeared to be decreasing with time between the late 1970s and the late 1990s. Some hiring criteria may be related to a particular group an applicant belongs to and not individual abilities. Unless membership in that group directly affects potential job performance, a decision based on group membership is discriminatory ( Figure 13.10 ). To combat hiring discrimination , in the United States there are numerous city, state, and federal laws that prevent hiring based on various group-membership criteria. For example, did you know it is illegal for a potential employer to ask your age in an interview? Did you know that an employer cannot ask you whether you are married, a U.S. citizen, have disabilities, or what your race or religion is? They cannot even ask questions that might shed some light on these attributes, such as where you were born or who you live with. These are only a few of the restrictions that are in place to prevent discrimination in hiring. In the United States, federal anti-discrimination laws are administered by the U.S. Equal Employment Opportunity Commission (EEOC). The U.S. Equal Employment Opportunity Commission (EEOC) The U.S. Equal Employment Opportunity Commission (EEOC) is responsible for enforcing federal laws that make it illegal to discriminate against a job applicant or an employee because of the person's race, color, religion, sex (including pregnancy), national origin, age (40 or older), disability, or genetic information. Figure 13.11 provides some of the legal language from laws that have been passed to prevent discrimination. The United States has several specific laws regarding fairness and avoidance of discrimination. The Equal Pay Act requires that equal pay for men and women in the same workplace who are performing equal work. Despite the law, persistent inequities in earnings between men and women exist. Corbett & Hill (2012) studied one facet of the gender gap by looking at earnings in the first year after college in the United States. Just comparing the earnings of women to men, women earn about 82 cents for every dollar a man earns in their first year out of college. However, some of this difference can be explained by education, career, and life choices, such as choosing majors with lower earning potential or specific jobs within a field that have less responsibility. When these factors were corrected the study found an unexplained seven-cents-on-the-dollar gap in the first year after college that can be attributed to gender discrimination in pay. This approach to analysis of the gender pay gap, called the human capital model, has been criticized. Lips (2013) argues that the education, career, and life choices can, in fact, be constrained by necessities imposed by gender discrimination. This suggests that removing these factors entirely from the gender gap equation leads to an estimate of the size of the pay gap that is too small. Title VII of the Civil Rights Act of 1964 makes it illegal to treat individuals unfavorably because of their race or color of their skin: An employer cannot discriminate based on skin color, hair texture, or other immutable characteristics , which are traits of an individual that are fundamental to her identity, in hiring, benefits, promotions, or termination of employees. The Pregnancy Discrimination Act of 1978 amends the Civil Rights Act; it prohibits job (e.g., employment, pay, and termination) discrimination of a woman because she is pregnant as long as she can perform the work required. The Supreme Court ruling in Griggs v. Duke Power Co. made it illegal under Title VII of the Civil Rights Act to include educational requirements in a job description (e.g., high school diploma) that negatively impacts one race over another if the requirement cannot be shown to be directly related to job performance. The EEOC (2014) received more than 94,000 charges of various kinds of employment discrimination in 2013. Many of the filings are for multiple forms of discrimination and include charges of retaliation for making a claim, which itself is illegal. Only a small fraction of these claims become suits filed in a federal court, although the suits may represent the claims of more than one person. In 2013, there were 148 suits filed in federal courts. Link to Learning In 2011, the U.S. Supreme Court decided a case in which women plaintiffs were attempting to group together in a class-action suit against Walmart for gender discrimination in promotion and pay. The case was important because it was the only practical way for individual women who felt they had been discriminated against to sustain a court battle for redress of their claims. The Court ultimately decided against the plaintiffs, and the right to a class-action suit was denied. However, the case itself effectively publicized the issue of gender discrimination in employment. This video discusses the case history and issues. This PBS NewsHour presents the arguments in the court case. Federal legislation does not protect employees in the private sector from discrimination related to sexual orientation and gender identity. These groups include lesbian, gay, bisexual, and transgender individuals. There is evidence of discrimination derived from surveys of workers, studies of complaint filings, wage comparison studies, and controlled job-interview studies (Badgett, Sears, Lau, & Ho, 2009). Federal legislation protects federal employees from such discrimination; the District of Columbia and 20 states have laws protecting public and private employees from discrimination for sexual orientation (American Civil Liberties Union, n.d). Most of the states with these laws also protect against discrimination based on gender identity. Gender identity, as discussed when you learned about sexual behavior, refers to one’s sense of being male or female. Many cities and counties have adopted local legislation preventing discrimination based on sexual orientation or gender identity (Human Rights Campaign, 2013a), and some companies have recognized a benefit to explicitly stating that their hiring must not discriminate on these bases (Human Rights Campaign, 2013b). Americans with Disabilities Act (ADA) The Americans with Disabilities Act (ADA) of 1990 states people may not be discriminated against due to the nature of their disability. A disability is defined as a physical or mental impairment that limits one or more major life activities such as hearing, walking, and breathing. An employer must make reasonable accommodations for the performance of a disabled employee’s job. This might include making the work facility handicapped accessible with ramps, providing readers for blind personnel, or allowing for more frequent breaks. The ADA has now been expanded to include individuals with alcoholism, former drug use, obesity, or psychiatric disabilities. The premise of the law is that disabled individuals can contribute to an organization and they cannot be discriminated against because of their disabilities (O'Keefe & Bruyere, 1994). The Civil Rights Act and the Age Discrimination in Employment Act make provisions for bona fide occupational qualifications (BFOQs) , which are requirements of certain occupations for which denying an individual employment would otherwise violate the law. For example, there may be cases in which religion, national origin, age, and sex are bona fide occupational qualifications. There are no BFOQ exceptions that apply to race, although the first amendment protects artistic expressions, such as films, in making race a requirement of a role. Clearcut examples of BFOQs would be hiring someone of a specific religion for a leadership position in a worship facility, or for an executive position in religiously affiliated institutions, such as the president of a university with religious ties. Age has been determined to be a BFOQ for airline pilots; hence, there are mandatory retirement ages for safety reasons. Sex has been determined as a BFOQ for guards in male prisons. Sex (gender) is the most common reason for invoking a BFOQ as a defense against accusing an employer of discrimination (Manley, 2009). Courts have established a three-part test for sex-related BFOQs that are often used in other types of legal cases for determining whether a BFOQ exists. The first of these is whether all or substantially all women would be unable to perform a job. This is the reason most physical limitations, such as “able to lift 30 pounds,” fail as reasons to discriminate because most women are able to lift this weight. The second test is the “essence of the business” test, in which having to choose the other gender would undermine the essence of the business operation. This test was the reason the now defunct Pan American World Airways (i.e., Pan Am) was told it could not hire only female flight attendants. Hiring men would not have undermined the essense of this business. On a deeper level, this means that hiring cannot be made purely on customers’ or others’ preferences. The third and final test is whether the employer cannot make reasonable alternative accomodations, such as reassigning staff so that a woman does not have to work in a male-only part of a jail or other gender-specific facility. Privacy concerns are a major reason why discrimination based on gender is upheld by the courts, for example in situations such as hires for nursing or custodial staff (Manley, 2009). Most cases of BFOQs are decided on a case-by-case basis and these court decisions inform policy and future case decisions. What Do You Think? Hooters and BFOQ Laws The restaurant chain Hooters, which hires only female wait staff and has them dress in a sexually provocative manner, is commonly cited as a discriminatory employer. The chain would argue that the female employees are an essential part of their business in that they market through sex appeal and the wait staff attract customers. Men have filed discrimination charges against Hooters in the past for not hiring them as wait staff simply because they are men. The chain has avoided a court decision on their hiring practices by settling out of court with the plaintiffs in each case. Do you think their practices violate the Civil Rights Act? See if you can apply the three court tests to this case and make a decision about whether a case that went to trial would find in favor of the plaintiff or the chain. 13.3 Organizational Psychology: The Social Dimension of Work Learning Objectives By the end of this section, you will be able to: Define organizational psychology Explain the measurement and determinants of job satisfaction Describe key elements of management and leadership Explain the significance of organizational culture Organizational psychology is the second major branch of study and practice within the discipline of industrial and organizational psychology. In organizational psychology , the focus is on social interactions and their effect on the individual and on the functioning of the organization. In this section, you will learn about the work organizational psychologists have done to understand job satisfaction, different styles of management, different styles of leadership, organizational culture, and teamwork. Job Satisfaction Some people love their jobs, some people tolerate their jobs, and some people cannot stand their jobs. Job satisfaction describes the degree to which individuals enjoy their job. It was described by Edwin Locke (1976) as the state of feeling resulting from appraising one’s job experiences. While job satisfaction results from both how we think about our work (our cognition) and how we feel about our work (our affect) (Saari & Judge, 2004), it is described in terms of affect. Job satisfaction is impacted by the work itself, our personality, and the culture we come from and live in (Saari & Judge, 2004). Job satisfaction is typically measured after a change in an organization, such as a shift in the management model, to assess how the change affects employees. It may also be routinely measured by an organization to assess one of many factors expected to affect the organization’s performance. In addition, polling companies like Gallup regularly measure job satisfaction on a national scale to gather broad information on the state of the economy and the workforce (Saad, 2012). Job satisfaction is measured using questionnaires that employees complete. Sometimes a single question might be asked in a very straightforward way to which employees respond using a rating scale, such as a Likert scale, which was discussed in the chapter on personality. A Likert scale (typically) provides five possible answers to a statement or question that allows respondents to indicate their positive-to-negative strength of agreement or strength of feeling regarding the question or statement. Thus the possible responses to a question such as “How satisfied are you with your job today?” might be “Very satisfied,” “Somewhat satisfied,” “Neither satisfied, nor dissatisfied,” “Somewhat dissatisfied,” and “Very dissatisfied.” More commonly the survey will ask a number of questions about the employee’s satisfaction to determine more precisely why he is satisfied or dissatisfied. Sometimes these surveys are created for specific jobs; at other times, they are designed to apply to any job. Job satisfaction can be measured at a global level, meaning how satisfied in general the employee is with work, or at the level of specific factors intended to measure which aspects of the job lead to satisfaction ( Table 13.1 ). Factor Description Autonomy Individual responsibility, control over decisions Work content Variety, challenge, role clarity Communication Feedback Financial rewards Salary and benefits Growth and development Personal growth, training, education Promotion Career advancement opportunity Coworkers Professional relations or adequacy Supervision and feedback Support, recognition, fairness Workload Time pressure, tedium Work demands Extra work requirements, insecurity of position Table 13.1 Factors Involved in Job Satisfaction–Dissatisfaction Research has suggested that the work-content factor, which includes variety, difficulty level, and role clarity of the job, is the most strongly predictive factor of overall job satisfaction (Saari & Judge, 2004). In contrast, there is only a weak correlation between pay level and job satisfaction (Judge, Piccolo, Podsakoff, Shaw, & Rich, 2010). Judge et al. (2010) suggest that individuals adjust or adapt to higher pay levels: Higher pay no longer provides the satisfaction the individual may have initially felt when her salary increased. Why should we care about job satisfaction? Or more specifically, why should an employer care about job satisfaction? Measures of job satisfaction are somewhat correlated with job performance; in particular, they appear to relate to organizational citizenship or discretionary behaviors on the part of an employee that further the goals of the organization (Judge & Kammeyer-Mueller, 2012). Job satisfaction is related to general life satisfaction, although there has been limited research on how the two influence each other or whether personality and cultural factors affect both job and general life satisfaction. One carefully controlled study suggested that the relationship is reciprocal: Job satisfaction affects life satisfaction positively, and vice versa (Judge & Watanabe, 1993). Of course, organizations cannot control life satisfaction’s influence on job satisfaction. Job satisfaction, specifically low job satisfaction, is also related to withdrawal behaviors, such as leaving a job or absenteeism (Judge & Kammeyer-Mueller, 2012). The relationship with turnover itself, however, is weak (Judge & Kammeyer-Mueller, 2012). Finally, it appears that job satisfaction is related to organizational performance, which suggests that implementing organizational changes to improve employee job satisfaction will improve organizational performance (Judge & Kammeyer-Mueller, 2012). There is opportunity for more research in the area of job satisfaction. For example, Weiss (2002) suggests that the concept of job satisfaction measurements have combined both emotional and cognitive concepts, and measurements would be more reliable and show better relationships with outcomes like performance if the measurement of job satisfaction separated these two possible elements of job satisfaction. Dig Deeper Job Satisfaction in Federal Government Agencies A 2013 study of job satisfaction in the U.S. federal government found indexes of job satisfaction plummeting compared to the private sector. The largest factor in the decline was satisfaction with pay, followed by training and development opportunities. The Partnership for Public Service, a nonprofit, nonpartisan organization, has conducted research on federal employee job satisfaction since 2003. Its primary goal is to improve the federal government’s management. However, the results also provide information to those interested in obtaining employment with the federal government. Among large agencies, the highest job satisfaction ranking went to NASA, followed by the Department of Commerce and the intelligence community. The lowest scores went to the Department of Homeland Security. The data used to derive the job satisfaction score come from three questions on the Federal Employee Viewpoint Survey. The questions are: I recommend my organization as a good place to work. Considering everything, how satisfied are you with your job? Considering everything, how satisfied are you with your organization? The questions have a range of six possible answers, spanning a range of strong agreement or satisfaction to strong disagreement or dissatisfaction. How would you answer these questions with regard to your own job? Would these questions adequately assess your job satisfaction? You can explore the Best Places To Work In The Federal Government study at their Web site: www.bestplacestowork.org. The Office of Personnel Management also produces a report based on their survey: www.fedview.opm.gov. Job stress affects job satisfaction. Job stress, or job strain, is caused by specific stressors in an occupation. Stress can be an ambigious term as it is used in common language. Stress is the perception and response of an individual to events judged as ovewhelming or threatening to the individual’s well-being (Gyllensten & Palmer, 2005). The events themselves are the stressors. Stress is a result of an employee’s perception that the demands placed on them exceed their ability to meet them (Gyllensten & Palmer, 2005), such as having to fill multiple roles in a job or life in general, workplace role ambiguity, lack of career progress, lack of job security, lack of control over work outcomes, isolation, work overload, discrimination, harrassment, and bullying (Colligan & Higgins, 2005). The stressors are different for women than men and these differences are a significant area of research (Gyllensten & Palmer, 2005). Job stress leads to poor employee health, job performance, and family life (Colligan & Higgins, 2005). As already mentioned, job insecurity contributes significantly to job stress. Two increasing threats to job security are downsizing events and corporate mergers. Businesses typically involve I-O psychologists in planning for, implementing, and managing these types of organizational change. Downsizing is an increasingly common response to a business’s pronounced failure to achieve profit goals, and it involves laying off a significant percentage of the company’s employees. Industrial-organizational psychologists may be involved in all aspects of downsizing: how the news is delivered to employees (both those being let go and those staying), how laid-off employees are supported (e.g., separation packages), and how retained employees are supported. The latter is important for the organization because downsizing events affect the retained employee’s intent to quit, organizational commitment, and job insecurity (Ugboro, 2006). In addition to downsizing as a way of responding to outside strains on a business, corporations often grow larger by combining with other businesses. This can be accomplished through a merger (i.e., the joining of two organizations of equal power and status) or an acquisition (i.e., one organization purchases the other). In an acquisition, the purchasing organization is usually the more powerful or dominant partner. In both cases, there is usually a duplication of services between the two companies, such as two accounting departments and two sales forces. Both departments must be merged, which commonly involves a reduction of staff ( Figure 13.13 ). This leads to organizational processes and stresses similar to those that occur in downsizing events. Mergers require determining how the organizational culture will change, to which employees also must adjust (van Knippenberg, van Knippenberg, Monden, & de Lima, 2002). There can be additional stress on workers as they lose their connection to the old organization and try to make connections with the new combined group (Amiot, Terry, Jimmieson, & Callan, 2006). Research in this area focuses on understanding employee reactions and making practical recommendations for managing these organizational changes. Work–Family Balance Many people juggle the demands of work life with the demands of their home life, whether it be caring for children or taking care of an elderly parent; this is known as work-family balance . We might commonly think about work interfering with family, but it is also the case that family responsibilities may conflict with work obligations (Carlson, Kacmar, & Williams, 2000). Greenhaus and Beutell (1985) first identified three sources of work–family conflicts: time devoted to work makes it difficult to fulfill requirements of family, or vice versa, strain from participation in work makes it difficult to fulfill requirements of family, or vice versa, and specific behaviors required by work make it difficult to fulfill the requirements of family, or vice versa. Women often have greater responsibility for family demands, including home care, child care, and caring for aging parents, yet men in the United States are increasingly assuming a greater share of domestic responsibilities. However, research has documented that women report greater levels of stress from work–family conflict (Gyllensten & Palmer, 2005). There are many ways to decrease work–family conflict and improve people’s job satisfaction (Posig & Kickul, 2004). These include support in the home, which can take various forms: emotional (listening), practical (help with chores). Workplace support can include understanding supervisors, flextime, leave with pay, and telecommuting. Flextime usually involves a requirement of core hours spent in the workplace around which the employee may schedule his arrival and departure from work to meet family demands. Telecommuting involves employees working at home and setting their own hours, which allows them to work during different parts of the day, and to spend part of the day with their family. Recall that Yahoo! had a policy of allowing employees to telecommute and then rescinded the policy. There are also organizations that have onsite daycare centers, and some companies even have onsite fitness centers and health clinics. In a study of the effectiveness of different coping methods, Lapierre & Allen (2006) found practical support from home more important than emotional support. They also found that immediate-supervisor support for a worker significantly reduced work–family conflict through such mechanisms as allowing an employee the flexibility needed to fulfill family obligations. In contrast, flextime did not help with coping and telecommuting actually made things worse, perhaps reflecting the fact that being at home intensifies the conflict between work and family because with the employee in the home, the demands of family are more evident. Posig & Kickul (2004) identify exemplar corporations with policies designed to reduce work–family conflict. Examples include IBM’s policy of three years of job-guaranteed leave after the birth of a child, Lucent Technologies offer of one year’s childbirth leave at half pay, and SC Johnson’s program of concierge services for daytime errands. Link to Learning Glassdoor is a website that posts job satisfaction reviews for different careers and organizations. Use this site to research possible careers and/or organizations that interest you. Management and Organizational Structure A significant portion of I-O research focuses on management and human relations. Douglas McGregor (1960) combined scientific management (a theory of management that analyzes and synthesizes workflows with the main objective of improving economic efficiency, especially labor productivity) and human relations into the notion of leadership behavior. His theory lays out two different styles called Theory X and Theory Y. In the Theory X approach to management, managers assume that most people dislike work and are not innately self-directed. Theory X managers perceive employees as people who prefer to be led and told which tasks to perform and when. Their employees have to be watched carefully to be sure that they work hard enough to fulfill the organization’s goals. Theory X workplaces will often have employees punch a clock when arriving and leaving the workplace: Tardiness is punished. Supervisors, not employees, determine whether an employee needs to stay late, and even this decision would require someone higher up in the command chain to approve the extra hours. Theory X supervisors will ignore employees’ suggestions for improved efficiency and reprimand employees for speaking out of order. These supervisors blame efficiency failures on individual employees rather than the systems or policies in place. Managerial goals are achieved through a system of punishments and threats rather than enticements and rewards. Managers are suspicious of employees’ motivations and always suspect selfish motivations for their behavior at work (e.g., being paid is their sole motivation for working). In the Theory Y approach, on the other hand, managers assume that most people seek inner satisfaction and fulfillment from their work. Employees function better under leadership that allows them to participate in, and provide input about, setting their personal and work goals. In Theory Y workplaces, employees participate in decisions about prioritizing tasks; they may belong to teams that, once given a goal, decide themselves how it will be accomplished. In such a workplace, employees are able to provide input on matters of efficiency and safety. One example of Theroy Y in action is the policy of Toyota production lines that allows any employee to stop the entire line if a defect or other issue appears, so that the defect can be fixed and its cause remedied (Toyota Motor Manufacturing, 2013). A Theory Y workplace will also meaningfully consult employees on any changes to the work process or management system. In addition, the organization will encourage employees to contribute their own ideas. McGregor (1960) characterized Theory X as the traditional method of management used in the United States. He agued that a Theory Y approach was needed to improve organizational output and the wellbeing of individuals. Table 13.2 summarizes how these two management approaches differ. Theory X Theory Y People dislike work and avoid it. People enjoy work and find it natural. People avoid responsibility. People are more satisified when given responsibility. People want to be told what to do. People want to take part in setting their own work goals. Goals are achieved through rules and punishments. Goals are achieved through enticements and rewards. Table 13.2 Theory X and Theory Y Management Styles Another management style was described by Donald Clifton, who focused his research on how an organization can best use an individual’s strengths, an approach he called strengths-based management. He and his colleagues interviewed 8,000 managers and concluded that it is important to focus on a person’s strengths, not their weaknesses. A strength is a particular enduring talent possessed by an individual that allows her to provide consistent, near-perfect performance in tasks involving that talent. Clifton argued that our strengths provide the greatest opportunity for growth (Buckingham & Clifton, 2001). An example of a strength is public speaking or the ability to plan a successful event. The strengths-based approach is very popular although its effect on organization performance is not well-studied. However, Kaiser & Overfield (2011) found that managers often neglected improving their weaknesses and overused their strengths, both of which interfered with performance. Leadership is an important element of management. Leadership styles have been of major interest within I-O research, and researchers have proposed numerous theories of leadership. Bass (1985) popularized and developed the concepts of transactional leadership versus transformational leadership styles. In transactional leadership , the focus is on supervision and organizational goals, which are achieved through a system of rewards and punishments (i.e., transactions). Transactional leaders maintain the status quo: They are managers. This is in contrast to the transformational leader. People who have transformational leadership possess four attributes to varying degrees: They are charismatic (highly liked role models), inspirational (optimistic about goal attainment), intellectually stimulating (encourage critical thinking and problem solving), and considerate (Bass, Avolio, & Atwater, 1996). As women increasingly take on leadership roles in corporations, questions have arisen as to whether there are differences in leadership styles between men and women (Eagly, Johannesen-Schmidt, & van Engen, 2003). Eagly & Johnson (1990) conducted a meta-analysis to examine gender and leadership style. They found, to a slight but significant degree, that women tend to practice an interpersonal style of leadership (i.e., she focuses on the morale and welfare of the employees) and men practice a task-oriented style (i.e., he focuses on accomplishing tasks). However, the differences were less pronounced when one looked only at organizational studies and excluded laboratory experiments or surveys that did not involve actual organizational leaders. Larger sex-related differences were observed when leadership style was categorized as democratic or autocratic, and these differences were consistent across all types of studies. The authors suggest that similarities between the sexes in leadership styles are attributable to both sexes needing to conform the organization’s culture; additionally, they propose that sex-related differences reflect inherent differences in the strengths each sex brings to bear on leadership practice. In another meta-analysis of leadership style, Eagly, Johannesen-Schmidt, & van Engen (2003) found that women tended to exhibit the characteristics of transformational leaders, while men were more likely to be transactional leaders. However, the differences are not absolute; for example, women were found to use methods of reward for performance more often than men, which is a component of transactional leadership. The differences they found were relatively small. As Eagly, Johannesen-Schmidt, & van Engen (2003) point out, research shows that transformational leadership approaches are more effective than transactional approaches, although individual leaders typically exhibit elements of both approaches. Goals, Teamwork and Work Teams The workplace today is rapidly changing due to a variety of factors, such as shifts in technology, economics, foreign competition, globalization, and workplace demographics. Organizations need to respond quickly to changes in these factors. Many companies are responding to these changes by structuring their organizations so that work can be delegated to work teams , which bring together diverse skills, experience, and expertise. This is in contrast to organizational structures that have individuals at their base (Naquin & Tynan, 2003). In the team-based approach, teams are brought together and given a specific task or goal to accomplish. Despite their burgeoning popularity, team structures do not always deliver greater productivity—the work of teams is an active area of research (Naquin & Tynan, 2003). Why do some teams work well while others do not? There are many contributing factors. For example, teams can mask team members that are not working (i.e., social loafing). Teams can be inefficient due to poor communication; they can have poor decision-making skills due to conformity effects; and, they can have conflict within the group. The popularity of teams may in part result from the team halo effect: Teams are given credit for their successes. but individuals within a team are blamed for team failures (Naquin & Tynan, 2003). One aspect of team diversity is their gender mix. Researchers have explored whether gender mix has an effect on team performance. On the one hand, diversity can introduce communication and interpersonal-relationship problems that hinder performance, but on the other hand diversity can also increase the team’s skill set, which may include skills that can actually improve team member interactions. Hoogendoorn, Oosterbeek, & van Praag (2013) studied project teams in a university business school in which the gender mix of the teams was manipulated. They found that gender-balanced teams (i.e., nearly equal numbers of men and women) performed better, as measured by sales and profits, than predominantly male teams. The study did not have enough data to determine the relative performance of female dominated teams. The study was unsuccessful in identifying which mechanism (interpersonal relationships, learning, or skills mixes) accounted for performance improvement. There are three basic types of teams: problem resolution teams, creative teams, and tactical teams. Problem resolution teams are created for the purpose of solving a particular problem or issue; for example, the diagnostic teams at the Centers for Disease Control. Creative teams are used to develop innovative possibilities or solutions; for example, design teams for car manufacturers create new vehicle models. Tactical teams are used to execute a well-defined plan or objective, such as a police or FBI SWAT team handling a hostage situation (Larson & LaFasto, 1989). One area of active research involves a fourth kind of team—the virtual team; these studies examine how groups of geographically disparate people brought together using digital communications technology function (Powell, Piccoli, & Ives, 2004). Virtual teams are more common due to the growing globalization of organizations and the use of consulting and partnerships facilitated by digital communication. Organizational Culture Each company and organization has an organizational culture. Organizational culture encompasses the values, visions, hierarchies, norms, and interactions among its employees. It is how an organization is run, how it operates, and how it makes decisions—the industry in which the organization participates may have an influence. Different departments within one company can develop their own subculture within the organization’s culture. Ostroff, Kinicki, and Tamkins (2003) identify three layers in organizational culture: observable artifacts, espoused values, and basic assumptions. Observable artifacts are the symbols, language (jargon, slang, and humor), narratives (stories and legends), and practices (rituals) that represent the underlying cultural assumptions. Espoused values are concepts or beliefs that the management or the entire organization endorses. They are the rules that allow employees to know which actions they should take in different situations and which information they should adhere to. These basic assumptions generally are unobservable and unquestioned. Researchers have developed survey instruments to measure organizational culture. With the workforce being a global marketplace, your company may have a supplier in Korea and another in Honduras and have employees in the United States, China, and South Africa. You may have coworkers of different religious, ethnic, or racial backgrounds than yourself. Your coworkers may be from different places around the globe. Many workplaces offer diversity training to help everyone involved bridge and understand cultural differences. Diversity training educates participants about cultural differences with the goal of improving teamwork. There is always the potential for prejudice between members of two groups, but the evidence suggests that simply working together, particularly if the conditions of work are set carefully that such prejudice can be reduced or eliminated. Pettigrew and Tropp (2006) conducted a meta-analysis to examine the question of whether contact between groups reduced prejudice between those groups. They found that there was a moderate but significant effect. They also found that, as previously theorized, the effect was enhanced when the two groups met under conditions in which they have equal standing, common goals, cooperation between the groups, and especially support on the part of the institution or authorities for the contact. Dig Deeper Managing Generational Differences An important consideration in managing employees is age. Workers’ expectations and attitudes are developed in part by experience in particular cultural time periods. Generational constructs are somewhat arbitrary, yet they may be helpful in setting broad directions to organizational management as one generation leaves the workforce and another enters it. The baby boomer generation (born between 1946 and 1964) is in the process of leaving the workforce and will continue to depart it for a decade or more. Generation X (born between the early 1960s and the 1980s) are now in the middle of their careers. Millennials (born from 1979 to the early 1994) began to come of age at the turn of the century, and are early in their careers. Today, as these three different generations work side by side in the workplace, employers and managers need to be able to identify their unique characteristics. Each generation has distinctive expectations, habits, attitudes, and motivations (Elmore, 2010). One of the major differences among these generations is knowledge of the use of technology in the workplace. Millennials are technologically sophisticated and believe their use of technology sets them apart from other generations. They have also been characterized as self-centered and overly self-confident. Their attitudinal differences have raised concerns for managers about maintaining their motivation as employees and their ability to integrate into organizational culture created by baby boomers (Myers & Sadaghiani, 2010). For example, millennials may expect to hear that they need to pay their dues in their jobs from baby boomers who believe they paid their dues in their time. Yet millennials may resist doing so because they value life outside of work to a greater degree (Myers & Sadaghiani, 2010). Meister & Willyerd (2010) suggest alternative approaches to training and mentoring that will engage millennials and adapt to their need for feedback from supervisors: reverse mentoring, in which a younger employee educates a senior employee in social media or other digital resources. The senior employee then has the opportunity to provide useful guidance within a less demanding role. Recruiting and retaining millennials and Generation X employees poses challenges that did not exist in previous generations. The concept of building a career with the company is not relatable to most Generation X employees, who do not expect to stay with one employer for their career. This expectation arises from of a reduced sense of loyalty because they do not expect their employer to be loyal to them (Gibson, Greenwood, & Murphy, 2009). Retaining Generation X workers thus relies on motivating them by making their work meaningful (Gibson, Greenwood, & Murphy, 2009). Since millennials lack an inherent loyalty to the company, retaining them also requires effort in the form of nurturing through frequent rewards, praise, and feedback. Millennials are also interested in having many choices, including options in work scheduling, choice of job duties, and so on. They also expect more training and education from their employers. Companies that offer the best benefit package and brand attract millennials (Myers & Sadaghiani, 2010). One well-recognized negative aspect of organizational culture is a culture of harassment , including sexual harassment. Most organizations of any size have developed sexual harassment policies that define sexual harassment (or harassment in general) and the procedures the organization has set in place to prevent and address it when it does occur. Thus, in most jobs you have held, you were probably made aware of the company’s sexual harassment policy and procedures, and may have received training related to the policy. The U.S. Equal Employment Opportunity Commission (n.d.) provides the following description of sexual harassment : Unwelcome sexual advances, requests for sexual favors, and other verbal or physical conduct of a sexual nature constitute sexual harassment when this conduct explicitly or implicitly affects an individual's employment, unreasonably interferes with an individual's work performance, or creates an intimidating, hostile, or offensive work environment. (par. 2) One form of sexual harassment is called quid pro quo. Quid pro quo means you give something to get something, and it refers to a situation in which organizational rewards are offered in exchange for sexual favors. Quid pro quo harassment is often between an employee and a person with greater power in the organization. For example, a supervisor might request an action, such as a kiss or a touch, in exchange for a promotion, a positive performance review, or a pay raise. Another form of sexual harassment is the threat of withholding a reward if a sexual request is refused. Hostile environment sexual harassment is another type of workplace harassment. In this situation, an employee experiences conditions in the workplace that are considered hostile or intimidating. For example, a work environment that allows offensive language or jokes or displays sexually explicit images. Isolated occurrences of these events do not constitute harassment, but a pattern of repeated occurrences does. In addition to violating organizational policies against sexual harassment, these forms of harassment are illegal. Harassment does not have to be sexual; it may be related to any of the protected classes in the statutes regulated by the EEOC: race, national origin, religion, or age. Violence in the Workplace In the summer of August 1986, a part-time postal worker with a troubled work history walked into the Edmond, Oklahoma, post office and shot and killed 15 people, including himself. From his action, the term “going postal” was coined, describing a troubled employee who engages in extreme violence. Workplace violence is one aspect of workplace safety that I-O psychologists study. Workplace violence is any act or threat of physical violence, harassment, intimidation, or other threatening, disruptive behavior that occurs at the workplace. It ranges from threats and verbal abuse to physical assaults and even homicide (Occupational Safety & Health Administration, 2014). There are different targets of workplace violence: a person could commit violence against coworkers, supervisors, or property. Warning signs often precede such actions: intimidating behavior, threats, sabotaging equipment, or radical changes in a coworker’s behavior. Often there is intimidation and then escalation that leads to even further escalation. It is important for employees to involve their immediate supervisor if they ever feel intimidated or unsafe. Murder is the second leading cause of death in the workplace. It is also the primary cause of death for women in the workplace. Every year there are nearly two million workers who are physically assaulted or threatened with assault. Many are murdered in domestic violence situations by boyfriends or husbands who chose the woman’s workplace to commit their crimes. There are many triggers for workplace violence. A significant trigger is the feeling of being treated unfairly, unjustly, or disrespectfully. In a research experiment, Greenberg (1993) examined the reactions of students who were given pay for a task. In one group, the students were given extensive explanations for the pay rate. In the second group, the students were given a curt uninformative explanation. The students were made to believe the supervisor would not know how much money the student withdrew for payment. The rate of stealing (taking more pay than they were told they deserved) was higher in the group who had been given the limited explanation. This is a demonstration of the importance of procedural justice in organizations. Procedural justice refers to the fairness of the processes by which outcomes are determined in conflicts with or among employees. In another study by Greenberg & Barling (1999), they found a history of aggression and amount of alcohol consumed to be accurate predictors of workplace violence against a coworker. Aggression against a supervisor was predicted if a worker felt unfairly treated or untrusted. Job security and alcohol consumption predicted aggression against a subordinate. To understand and predict workplace violence, Greenberg & Barling (1999) emphasize the importance of considering the employee target of aggression or violence and characteristics of both the workplace characteristics and the aggressive or violent person. 13.4 Human Factors Psychology and Workplace Design Learning Objectives By the end of this section, you will be able to: Describe the field of human factors psychology Explain the role of human factors psychology in safety, productivity, and job satisfaction Human factors psychology (or ergonomics, a term that is favored in Europe) is the third subject area within industrial and organizational psychology. This field is concerned with the integration of the human-machine interface in the workplace, through design, and specifically with researching and designing machines that fit human requirements. The integration may be physical or cognitive, or a combination of both. Anyone who needs to be convinced that the field is necessary need only try to operate an unfamiliar television remote control or use a new piece of software for the first time. Whereas the two other areas of I-O psychology focus on the interface between the worker and team, group, or organization, human factors psychology focuses on the individual worker’s interaction with a machine, work station, information displays, and the local environment, such as lighting. In the United States, human factors psychology has origins in both psychology and engineering; this is reflected in the early contributions of Lillian Gilbreth (psychologist and engineer) and her husband Frank Gilbreth (engineer). Human factor professionals are involved in design from the beginning of a project, as is more common in software design projects, or toward the end in testing and evaluation, as is more common in traditional industries (Howell, 2003). Another important role of human factor professionals is in the development of regulations and principles of best design. These regulations and principles are often related to work safety. For example, the Three Mile Island nuclear accident lead to Nuclear Regulatory Commission (NRC) requirements for additional instrumentation in nuclear facilities to provide operators with more critical information and increased operator training (United States Nuclear Regulatory Commission, 2013). The American National Standards Institute (ANSI, 2000), an independent developer of industrial standards, develops many standards related to ergonomic design, such as the design of control-center workstations that are used for transportation control or industrial process control. Many of the concerns of human factors psychology are related to workplace safety. These concerns can be studied to help prevent work-related injuries of individual workers or those around them. Safety protocols may also be related to activities, such as commercial driving or flying, medical procedures, and law enforcement, that have the potential to impact the public. One of the methods used to reduce accidents in the workplace is a checklist . The airline industry is one industry that uses checklists. Pilots are required to go through a detailed checklist of the different parts of the aircraft before takeoff to ensure that all essential equipment is working correctly. Astronauts also go through checklists before takeoff. The surgical safety checklist shown in Figure 13.14 was developed by the World Health Organization (WHO) and serves as the basis for many checklists at medical facilities. Safety concerns also lead to limits to how long an operator, such as a pilot or truck driver, is allowed to operate the equipment. Recently the Federal Aviation Administration (FAA) introduced limits for how long a pilot is allowed to fly without an overnight break. Howell (2003) outlines some important areas of research and practice in the field of human factors. These are summarized in Table 13.3 . Area Description I-O Questions Attention Includes vigilance and monitoring, recognizing signals in noise, mental resources, and divided attention How is attention maintained? What about tasks maintains attention? How to design systems to support attention? Cognitive engineering Includes human software interactions in complex automated systems, especially the decision-making processes of workers as they are supported by the software system How do workers use and obtain information provided by software? Task analysis Breaking down the elements of a task How can a task be performed more efficiently? How can a task be performed more safely? Cognitive task analysis Breaking down the elements of a cognitive task How are decisions made? Table 13.3 Areas of Study in Human Factors Psychology As an example of research in human factors psychology Bruno & Abrahão (2012) examined the impact of the volume of operator decisions on the accuracy of decisions made within an information security center at a banking institution in Brazil. The study examined a total of about 45,000 decisions made by 35 operators and 4 managers over a period of 60 days. Their study found that as the number of decisions made per day by the operators climbed, that is, as their cognitive effort increased, the operators made more mistakes in falsely identifying incidents as real security breaches (when, in reality, they were not). Interestingly, the opposite mistake of identifying real intrusions as false alarms did not increase with increased cognitive demand. This appears to be good news for the bank, since false alarms are not as costly as incorrectly rejecting a genuine threat. These kinds of studies combine research on attention, perception, teamwork, and human–computer interactions in a field of considerable societal and business significance. This is exactly the context of the events that led to the massive data breach for Target in the fall of 2013. Indications are that security personnel received signals of a security breach but did not interpret them correctly, thus allowing the breach to continue for two weeks until an outside agency, the FBI, informed the company (Riley, Elgin, Lawrence, & Matlack, 2014).
introduction_to_sociology
Learning Objectives 9.1 What Is Social Stratification? Differentiate between open and closed stratification systems Distinguish between caste and class systems Understand meritocracy as an ideal system of stratification 9.2 Social Stratification and Mobility in the United States Understand America’s class structure Describe several types of social mobility Recognize characteristics that define and identify class 9.3 Global Stratification and Inequality Define global stratification Describe different sociological models for understanding global stratification Understand how studies of global stratification identify worldwide inequalities 9.4 Theoretical Perspectives on Social Stratification Understand and apply functionalist, conflict theory, and interactionist perspectives on social stratification Introduction to Social Stratification in the United States Robert and Joan have spent their entire lives in Cudahy, Wisconsin, a small town of about 18,000. The high school sweethearts got married after graduation and later bought a house. After Robert served two years in the Army, he came home and accepted a job in a foundry, working on machinery and equipment. Joan worked as a hotel receptionist until she quit her job to raise their two children, Michael and Lisa. Robert and Joan worked hard to make sure their kids had good lives. The kids went to Cudahy High School, like their parents, and took part in many extracurricular activities. Michael played football and Lisa participated in the debate team and Spanish Club, and served as class vice president. After high school, Michael’s and Lisa’s lives took two divergent paths. Michael stayed close to home, earning a degree in hotel management at a community college. He began working the front desk of a downtown Milwaukee hotel, a job similar to the one his mother held so long ago. He married Donna, a high school classmate who now worked in a day-care center. The couple bought a house two miles from his parents and eventually had three children of their own. Lisa’s experiences, meanwhile, took her from place to place. She double-majored in psychology and social work at the University of Wisconsin-Madison, then was accepted to the University of California-Berkeley, where she earned her master’s and doctoral degrees in Social Welfare. She worked as a teaching assistant and helped organize a summit on institutional racism. Lisa received a grant to start a Hispanic youth program in Denver, Colorado. There, she met Mario, a cook, and helped him learn English. The couple soon got married and moved into an apartment in a poor section of the city. They had a daughter, Alaina. Soon after, Lisa accepted an assistant professorship at the University of Colorado. That summer, while visiting her hometown of Cudahy, Lisa revealed some surprising news to her parents. She explained that she, Mario, and Alaina, were moving to Torreón, Mexico, to be close to Mario’s family. Lisa would do research for a book proposal she’d written and guest lectured at the nearby university. They planned to return in two or three years, in time for Alaina to start school in the United States. Robert and Joan were proud of their children. Michael and Lisa both had happy marriages, healthy children, and secure jobs. However, Robert and Joan puzzled over the different life paths their children took. Michael married a local woman, worked in the area, and stayed close with family and friends. Lisa moved far from home, married a foreigner, was fluent in two languages, and wanted to live in a foreign country. Joan and Robert had trouble understanding their daughter’s choices. Michael was a chip off the old block, while Lisa seemed like a stranger.
[ { "answer": { "ans_choice": 1, "ans_text": "People cannot change their social standings." }, "bloom": "1", "hl_context": "<hl> In the Hindu caste tradition , people were expected to work in the occupation of their caste and to enter into marriage according to their caste . <hl> <hl> Accepting this social standing was considered a moral duty . <hl> Cultural values reinforced the system . Caste systems promote beliefs in fate , destiny , and the will of a higher power , rather than promoting individual freedom as a value . A person who lived in a caste society was socialized to accept his or her social standing . <hl> Caste systems are closed stratification systems in which people can do little or nothing to change their social standing . <hl> A caste system is one in which people are born into their social standing and will remain in it their whole lives . People are assigned occupations regardless of their talents , interests , or potential . There are virtually no opportunities to improve one ’ s social position . Sociologists distinguish between two types of systems of stratification . <hl> Closed systems accommodate little change in social position . <hl> They do not allow people to shift levels and do not permit social relations between levels . Open systems , which are based on achievement , allow movement and interaction between layers and classes . Different systems reflect , emphasize , and foster certain cultural values , and shape individual beliefs . Stratification systems include class systems and caste systems , as well as meritocracy .", "hl_sentences": "In the Hindu caste tradition , people were expected to work in the occupation of their caste and to enter into marriage according to their caste . Accepting this social standing was considered a moral duty . Caste systems are closed stratification systems in which people can do little or nothing to change their social standing . Closed systems accommodate little change in social position .", "question": { "cloze_format": "A factor that makes caste systems closed is that ___ .", "normal_format": "What factor makes caste systems closed?", "question_choices": [ "They are run by secretive governments.", "People cannot change their social standings.", "Most have been outlawed.", "They exist only in rural areas." ], "question_id": "fs-id1427950", "question_text": "What factor makes caste systems closed?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 0, "ans_text": "They allow for movement between the classes." }, "bloom": null, "hl_context": "To illustrate , let ’ s consider Susan . Susan earned her high school degree but did not go on to college . That factor is a trait of the lower-middle class . She began doing landscaping work , which , as manual labor , is also a trait of lower-middle or even lower class . However , over time , Susan started her own company . She hired employees . She won larger contracts . She became a business owner and earned a lot of money . Those traits represent the upper-middle class . Here there are inconsistencies between Susan ’ s educational level , her occupation , and her income . <hl> In a class system , a person can work hard and have little education and still be in middle or upper class , whereas in a caste system that would not be possible . <hl> In a class system , low status consistency correlates with having more choices and opportunities . A class system is based on both social factors and individual achievement . A class consists of a set of people who share similar status with regard to factors like wealth , income , education , and occupation . <hl> Unlike caste systems , class systems are open . <hl> <hl> People are free to gain a different level of education or employment than their parents . <hl> They can also socialize with and marry members of other classes , allowing people to move from one class to another . Sociologists distinguish between two types of systems of stratification . Closed systems accommodate little change in social position . They do not allow people to shift levels and do not permit social relations between levels . <hl> Open systems , which are based on achievement , allow movement and interaction between layers and classes . <hl> Different systems reflect , emphasize , and foster certain cultural values , and shape individual beliefs . Stratification systems include class systems and caste systems , as well as meritocracy .", "hl_sentences": "In a class system , a person can work hard and have little education and still be in middle or upper class , whereas in a caste system that would not be possible . Unlike caste systems , class systems are open . People are free to gain a different level of education or employment than their parents . Open systems , which are based on achievement , allow movement and interaction between layers and classes .", "question": { "cloze_format": "The factor that makes class systems open is that ___.", "normal_format": "What factor makes class systems open?", "question_choices": [ "They allow for movement between the classes.", "People are more open-minded.", "People are encouraged to socialize within their class.", "They do not have clearly defined layers." ], "question_id": "fs-id1586451", "question_text": "What factor makes class systems open?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 3, "ans_text": "Class" }, "bloom": "1", "hl_context": "<hl> Social Mobility Social mobility refers to the ability to change positions within a social stratification system . <hl> <hl> When people improve or diminish their economic status in a way that affects social class , they experience social mobility . <hl> <hl> Britain ’ s monarchy arose during the Middle Ages . <hl> <hl> Its social hierarchy placed royalty at the top and commoners on the bottom . <hl> This was generally a closed system , with people born into positions of nobility . Wealth was passed from generation to generation through primogeniture , a law stating that all property would be inherited by the firstborn son . If the family had no son , the land went to the next closest male relation . Women could not inherit property and their social standing was primarily determined through marriage . <hl> A class system is based on both social factors and individual achievement . <hl> A class consists of a set of people who share similar status with regard to factors like wealth , income , education , and occupation . Unlike caste systems , class systems are open . People are free to gain a different level of education or employment than their parents . They can also socialize with and marry members of other classes , allowing people to move from one class to another . <hl> Caste systems are closed stratification systems in which people can do little or nothing to change their social standing . <hl> A caste system is one in which people are born into their social standing and will remain in it their whole lives . People are assigned occupations regardless of their talents , interests , or potential . There are virtually no opportunities to improve one ’ s social position .", "hl_sentences": "Social Mobility Social mobility refers to the ability to change positions within a social stratification system . When people improve or diminish their economic status in a way that affects social class , they experience social mobility . Britain ’ s monarchy arose during the Middle Ages . Its social hierarchy placed royalty at the top and commoners on the bottom . A class system is based on both social factors and individual achievement . Caste systems are closed stratification systems in which people can do little or nothing to change their social standing .", "question": { "cloze_format": "The system that allows for the most social mobility is ___ .", "normal_format": "Which of these systems allows for the most social mobility?", "question_choices": [ "Caste", "Monarchy", "Endogamy", "Class" ], "question_id": "fs-id2667975", "question_text": "Which of these systems allows for the most social mobility?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 1, "ans_text": "First-generation college student" }, "bloom": "4", "hl_context": "<hl> Upward mobility refers to an increase — or upward shift — in social class . <hl> In the United States , people applaud the rags-to-riches achievements of celebrities like Jennifer Lopez or Michael Jordan . Bestselling author Stephen King worked as a janitor prior to being published . Oprah Winfrey grew up in poverty in rural Mississippi before becoming a powerful media personality . There are many stories of people rising from modest beginnings to fame and fortune . But the truth is that relative to the overall population , the number of people who launch from poverty to wealth is very small . <hl> Still , upward mobility is not only about becoming rich and famous . <hl> <hl> In the United States , people who earn a college degree , get a job promotion , or marry someone with a good income may move up socially . <hl>", "hl_sentences": "Upward mobility refers to an increase — or upward shift — in social class . Still , upward mobility is not only about becoming rich and famous . In the United States , people who earn a college degree , get a job promotion , or marry someone with a good income may move up socially .", "question": { "cloze_format": "The person that best illustrates opportunities for upward social mobility in the United States is the ___ .", "normal_format": "Which person best illustrates opportunities for upward social mobility in the United States?", "question_choices": [ "First-shift factory worker", "First-generation college student", "Firstborn son who inherits the family business", "First-time interviewee who is hired for a job" ], "question_id": "fs-id1653063", "question_text": "Which person best illustrates opportunities for upward social mobility in the United States?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 2, "ans_text": "A college dropout launches an online company that earns millions in its first year." }, "bloom": "4", "hl_context": "To illustrate , let ’ s consider Susan . Susan earned her high school degree but did not go on to college . That factor is a trait of the lower-middle class . She began doing landscaping work , which , as manual labor , is also a trait of lower-middle or even lower class . However , over time , Susan started her own company . She hired employees . She won larger contracts . She became a business owner and earned a lot of money . Those traits represent the upper-middle class . Here there are inconsistencies between Susan ’ s educational level , her occupation , and her income . <hl> In a class system , a person can work hard and have little education and still be in middle or upper class , whereas in a caste system that would not be possible . <hl> In a class system , low status consistency correlates with having more choices and opportunities . Social stratification systems determine social position based on factors like income , education , and occupation . <hl> Sociologists use the term status consistency to describe the consistency , or lack thereof , of an individual ’ s rank across these factors . <hl> <hl> Caste systems correlate with high status consistency , whereas the more flexible class system has lower status consistency . <hl>", "hl_sentences": "In a class system , a person can work hard and have little education and still be in middle or upper class , whereas in a caste system that would not be possible . Sociologists use the term status consistency to describe the consistency , or lack thereof , of an individual ’ s rank across these factors . Caste systems correlate with high status consistency , whereas the more flexible class system has lower status consistency .", "question": { "cloze_format": "The statement that illustrates low status consistency is ___.", "normal_format": "Which statement illustrates low status consistency?", "question_choices": [ "A suburban family lives in a modest ranch home and enjoys nice vacation each summer.", "A single mother receives food stamps and struggles to find adequate employment.", "A college dropout launches an online company that earns millions in its first year.", "A celebrity actress owns homes in three countries." ], "question_id": "fs-id2638324", "question_text": "Which statement illustrates low status consistency?" }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 3, "ans_text": "earn a pay raise for doing excellent work" }, "bloom": null, "hl_context": "<hl> Meritocracy is another system of social stratification in which personal effort — or merit — determines social standing . <hl> <hl> High levels of effort will lead to a high social position , and vice versa . <hl> <hl> The concept of meritocracy is an ideal — that is , a society has never existed where social rank was based purely on merit . <hl> Because of the complex structure of societies , processes like socialization , and the realities of economic systems , social standing is influenced by multiple factors , not merit alone . Inheritance and pressure to conform to norms , for instance , disrupt the notion of a pure meritocracy . Sociologists see aspects of meritocracies in modern societies when they study the role of academic performance and job performance , and the systems in place for evaluating and rewarding achievement in these areas .", "hl_sentences": "Meritocracy is another system of social stratification in which personal effort — or merit — determines social standing . High levels of effort will lead to a high social position , and vice versa . The concept of meritocracy is an ideal — that is , a society has never existed where social rank was based purely on merit .", "question": { "cloze_format": "Based on meritocracy, a physician’s assistant would ___.", "normal_format": "Based on meritocracy, what would a physician’s assistant be?", "question_choices": [ "receive the same pay as all the other physician’s assistants", "be encouraged to earn a higher degree to seek a better position", "most likely marry a professional at the same level", "earn a pay raise for doing excellent work" ], "question_id": "fs-id1414894", "question_text": "Based on meritocracy, a physician’s assistant would:" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 0, "ans_text": "middle class" }, "bloom": null, "hl_context": "<hl> Many people call themselves middle class , but there are differing ideas about what that means . <hl> People with annual incomes of $ 150,000 call themselves middle class , as do people who annually earn $ 30,000 . That helps explain why , in the United States , the middle class is broken into upper and lower subcategories . For sociologists , too , categorizing class is a fluid science . Sociologists general identify three levels of class in the United States : upper , middle , and lower class . Within each class , there are many subcategories . Wealth is the most significant way of distinguishing classes , because wealth can be transferred to one ’ s children , perpetuating the class structure . One economist , J . D . <hl> Foster , defines the 20 percent of America ’ s highest earners as “ upper income , ” and the lower 20 percent as “ lower income . ” The remaining 60 percent of the population make up the middle class . <hl> But by that distinction , annual household incomes for the middle class range between $ 25,000 and $ 100,000 ( Mason and Sullivan 2010 ) . How can a person earning $ 25,000 a year have the same standing as someone earning $ 100,000 a year — four times as much ?", "hl_sentences": "Many people call themselves middle class , but there are differing ideas about what that means . Foster , defines the 20 percent of America ’ s highest earners as “ upper income , ” and the lower 20 percent as “ lower income . ” The remaining 60 percent of the population make up the middle class .", "question": { "cloze_format": "In the United States, most people define themselves as ___ .", "normal_format": "How do most people define themselves in the United States?", "question_choices": [ "middle class", "upper class", "lower class", "no specific class" ], "question_id": "fs-id1681158", "question_text": "In the United States, most people define themselves as:" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 2, "ans_text": "a large group moves up or down the class ladder due to societal changes" }, "bloom": null, "hl_context": "<hl> Structural mobility happens when societal changes enable a whole group of people to move up or down the social class ladder . <hl> <hl> Structural mobility is attributable to changes in society as a whole , not individual changes . <hl> In the first half of the 20th century , industrialization expanded the U . S . economy , raising the standard of living and leading to upward structural mobility . In today ’ s work economy , the recession and the outsourcing of jobs overseas have contributed to high unemployment rates . Many people have experienced economic setbacks , creating a wave of downward structural mobility .", "hl_sentences": "Structural mobility happens when societal changes enable a whole group of people to move up or down the social class ladder . Structural mobility is attributable to changes in society as a whole , not individual changes .", "question": { "cloze_format": "Structural mobility occurs when ___ .", "normal_format": "When Structural mobility occurs?", "question_choices": [ "an individual moves up the class ladder", "an individual moves down the class ladder", "a large group moves up or down the class ladder due to societal changes", "a member of a family belongs to a different class than his or her siblings" ], "question_id": "fs-id2020662", "question_text": "Structural mobility occurs when:" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 0, "ans_text": "class traits" }, "bloom": "1", "hl_context": "<hl> Class traits , also called class markers , are the typical behaviors , customs , and norms that define each class . <hl> Class traits indicate the level of exposure a person has to a wide range of cultures . Class traits also indicate the amount of resources a person has to spend on items like hobbies , vacations , and leisure activities .", "hl_sentences": "Class traits , also called class markers , are the typical behaviors , customs , and norms that define each class .", "question": { "cloze_format": "The behaviors, customs, and norms associated with a class are known as ___.", "normal_format": "What are the behaviors, customs, and norms associated with a class known as?", "question_choices": [ "class traits", "power", "prestige", "underclass" ], "question_id": "fs-id935393", "question_text": "The behaviors, customs, and norms associated with a class are known as:" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 1, "ans_text": "An executive belongs to a different class than her parents." }, "bloom": "1", "hl_context": "<hl> Intragenerational mobility describes a difference in social class that between different members of the same generation . <hl> For example , the wealth and prestige experienced by one person may be quite different from that of his or her siblings . <hl> Intergenerational mobility explains a difference in social class between different generations of a family . <hl> <hl> For example , an upper-class executive may have parents who belonged to the middle class . <hl> In turn , those parents may have been raised in the lower class . Patterns of intergenerational mobility can reflect long-term societal changes .", "hl_sentences": "Intragenerational mobility describes a difference in social class that between different members of the same generation . Intergenerational mobility explains a difference in social class between different generations of a family . For example , an upper-class executive may have parents who belonged to the middle class .", "question": { "cloze_format": "The scenario that is an example of intergenerational mobility is ___.", "normal_format": "Which of the following scenarios is an example of intergenerational mobility?", "question_choices": [ "A janitor belongs to the same social class as his grandmother did.", "An executive belongs to a different class than her parents.", "An editor shares the same social class as his cousin.", "A lawyer belongs to a different class than her sister." ], "question_id": "fs-id1299634", "question_text": "Which of the following scenarios is an example of intergenerational mobility?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 1, "ans_text": "not equally valued" }, "bloom": "1", "hl_context": "<hl> Most sociologists define social class as a grouping based on similar social factors like wealth , income , education , and occupation . <hl> <hl> These factors affect how much power and prestige a person has . <hl> Social stratification reflects an unequal distribution of resources . In most cases , having more money means having more power or more opportunities . Stratification can also result from physical and intellectual traits . Categories that affect social standing include family ancestry , race , ethnicity , age , and gender . In the United States , standing can also be defined by characteristics such as IQ , athletic abilities , appearance , personal skills , and achievements .", "hl_sentences": "Most sociologists define social class as a grouping based on similar social factors like wealth , income , education , and occupation . These factors affect how much power and prestige a person has .", "question": { "cloze_format": "Occupational prestige means that jobs are ___.", "normal_format": "What does occupational prestige mean regarding jobs?", "question_choices": [ "all equal in status", "not equally valued", "assigned to a person for life", "not part of a person’s self-identity" ], "question_id": "fs-id1295165", "question_text": "Occupational prestige means that jobs are:" }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 0, "ans_text": "ranks society members into categories" }, "bloom": null, "hl_context": "<hl> Social stratification systems determine social position based on factors like income , education , and occupation . <hl> Sociologists use the term status consistency to describe the consistency , or lack thereof , of an individual ’ s rank across these factors . Caste systems correlate with high status consistency , whereas the more flexible class system has lower status consistency . Sociologists use the term social stratification to describe the system of social standing . <hl> Social stratification refers to a society ’ s categorization of its people into rankings of socioeconomic tiers based on factors like wealth , income , race , education , and power . <hl>", "hl_sentences": "Social stratification systems determine social position based on factors like income , education , and occupation . Social stratification refers to a society ’ s categorization of its people into rankings of socioeconomic tiers based on factors like wealth , income , race , education , and power .", "question": { "cloze_format": "Social stratification is a system that ___ .", "normal_format": "What is a system of social stratification?", "question_choices": [ "ranks society members into categories", "destroys competition between society members", "allows society members to choose their social standing", "reflects personal choices of society members" ], "question_id": "fs-id2648812", "question_text": "Social stratification is a system that:" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 3, "ans_text": "Pyramid" }, "bloom": "1", "hl_context": "<hl> You may remember the word “ stratification ” from geology class . <hl> The distinct vertical layers found in rock , called stratification , are a good way to visualize social structure . <hl> Society ’ s layers are made of people , and society ’ s resources are distributed unevenly throughout the layers . <hl> <hl> The people who have more resources represent the top layer of the social structure of stratification . <hl> Other groups of people , with progressively fewer and fewer resources , represent the lower layers of our society . <hl> Sociologists use the term social stratification to describe the system of social standing . <hl> <hl> Social stratification refers to a society ’ s categorization of its people into rankings of socioeconomic tiers based on factors like wealth , income , race , education , and power . <hl>", "hl_sentences": "You may remember the word “ stratification ” from geology class . Society ’ s layers are made of people , and society ’ s resources are distributed unevenly throughout the layers . The people who have more resources represent the top layer of the social structure of stratification . Sociologists use the term social stratification to describe the system of social standing . Social stratification refers to a society ’ s categorization of its people into rankings of socioeconomic tiers based on factors like wealth , income , race , education , and power .", "question": { "cloze_format": "The graphic concept that best illustrates the concept of social stratification is ___.", "normal_format": "Which graphic concept best illustrates the concept of social stratification?", "question_choices": [ "Pie chart", "Flag poles", "Planetary movement", "Pyramid" ], "question_id": "fs-id2105897", "question_text": "Which graphic concept best illustrates the concept of social stratification?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 2, "ans_text": "the average annual income of a country’s citizens" }, "bloom": "1", "hl_context": "<hl> GNI , or gross national income , measures the current value of goods and services produced by a country . <hl> PPP , or purchasing power parity , measures the relative power a country has to purchase those same goods and services . So , GNI refers to productive output and PPP refers to buying power . The total figure is divided by the number of residents living in a country to establish the average income of a resident of that country .", "hl_sentences": "GNI , or gross national income , measures the current value of goods and services produced by a country .", "question": { "cloze_format": "Ethnicity describes shared ___ .", "normal_format": "What does ethnicity describe as shared?", "question_choices": [ "a country’s total accumulated wealth", "annual government spending", "the average annual income of a country’s citizens", "a country’s debt" ], "question_id": "fs-id1386692", "question_text": "The GNI PPP figure represents:" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 2, "ans_text": "serves a purpose in society" }, "bloom": null, "hl_context": "<hl> The Davis-Moore thesis , though open for debate , was an early attempt to explain why stratification exists . <hl> <hl> The thesis states that social stratification is necessary to promote excellence , productivity , and efficiency , thus giving people something to strive for . <hl> <hl> Davis and Moore believed that the system serves society as a whole because it allows everyone to benefit to a certain extent . <hl> In 1945 , sociologists Kingsley Davis and Wilbert Moore published the Davis-Moore thesis , which argued that the greater the functional importance of a social role , the greater must be the reward . <hl> The theory posits that social stratification represents the inherently unequal value of different work . <hl> <hl> Certain tasks in society are more valuable than others . <hl> <hl> Qualified people who fill those positions must be rewarded more than others . <hl>", "hl_sentences": "The Davis-Moore thesis , though open for debate , was an early attempt to explain why stratification exists . The thesis states that social stratification is necessary to promote excellence , productivity , and efficiency , thus giving people something to strive for . Davis and Moore believed that the system serves society as a whole because it allows everyone to benefit to a certain extent . The theory posits that social stratification represents the inherently unequal value of different work . Certain tasks in society are more valuable than others . Qualified people who fill those positions must be rewarded more than others .", "question": { "cloze_format": "The basic premise of the Davis-Moore thesis is that the unequal distribution of rewards in social stratification ___.", "normal_format": "What is the unequal distribution of rewards in social stratification according to the basic premise of the Davis-Moore thesis?", "question_choices": [ "is an outdated mode of societal organization", "is an artificial reflection of society", "serves a purpose in society", "cannot be justified" ], "question_id": "fs-id2039762", "question_text": "The basic premise of the Davis-Moore thesis is that the unequal distribution of rewards in social stratification:" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 0, "ans_text": "denied the opportunity to obtain" }, "bloom": "2", "hl_context": "In 1953 , Melvin Tumin countered the Davis-Moore thesis in “ Some Principles of Stratification : A Critical Analysis . ” Tumin questioned what determined a job ’ s degree of importance . The Davis-Moore thesis does not explain , he argued , why a media personality with little education , skill , or talent becomes famous and rich on a reality show or a campaign trail . <hl> The thesis also does not explain inequalities in the education system , or inequalities due to race or gender . <hl> <hl> Tumin believed social stratification prevented qualified people from attempting to fill roles ( Tumin 1953 ) . <hl> <hl> For example , an underprivileged youth has less chance of becoming a scientist , no matter how smart she is , because of the relative lack of opportunity available to her . <hl>", "hl_sentences": "The thesis also does not explain inequalities in the education system , or inequalities due to race or gender . Tumin believed social stratification prevented qualified people from attempting to fill roles ( Tumin 1953 ) . For example , an underprivileged youth has less chance of becoming a scientist , no matter how smart she is , because of the relative lack of opportunity available to her .", "question": { "cloze_format": "Unlike Davis and Moore, Melvin Tumin believed that, because of social stratification, some qualified people were _______ higher-level job positions.", "normal_format": "Which of the following is correct about some qualified people and higher-level job positions?", "question_choices": [ "denied the opportunity to obtain", "encouraged to train for", "often fired from", "forced into" ], "question_id": "fs-id2431592", "question_text": "Unlike Davis and Moore, Melvin Tumin believed that, because of social stratification, some qualified people were _______ higher-level job positions." }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 1, "ans_text": "After work, Pat, a janitor, feels more comfortable eating in a truck stop than a French restaurant." }, "bloom": "3", "hl_context": "<hl> Symbolic interactionism is a theory that uses everyday interactions of individuals to explain society as a whole . <hl> <hl> Symbolic interactionism examines stratification from a micro-level perspective . <hl> <hl> This analysis strives to explain how people ’ s social standing affects their everyday interactions . <hl>", "hl_sentences": "Symbolic interactionism is a theory that uses everyday interactions of individuals to explain society as a whole . Symbolic interactionism examines stratification from a micro-level perspective . This analysis strives to explain how people ’ s social standing affects their everyday interactions .", "question": { "cloze_format": "___ is a statement that represents stratification from the perspective of symbolic interactionism.", "normal_format": "Which statement represents stratification from the perspective of symbolic interactionism?", "question_choices": [ "Men often earn more than women, even working the same job.", "After work, Pat, a janitor, feels more comfortable eating in a truck stop than a French restaurant.", "Doctors earn more money because their job is more highly valued.", "Teachers continue to struggle to keep benefits such as health insurance." ], "question_id": "fs-id2729101", "question_text": "Which statement represents stratification from the perspective of symbolic interactionism?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 1, "ans_text": "do not feel connected to their work" }, "bloom": null, "hl_context": "Many conflict theorists draw on the work of Karl Marx . During the 19th - century era of industrialization , Marx believed social stratification resulted from people ’ s relationship to production . People were divided by a single line : they either owned factories or worked in them . In Marx ’ s time , bourgeois capitalists owned high-producing businesses , factories , and land , as they still do today . Proletariats were the workers who performed the manual labor to produce goods . Upper-class capitalists raked in profits and got rich , while working-class proletariats earned skimpy wages and struggled to survive . With such opposing interests , the two groups were divided by differences of wealth and power . <hl> Marx saw workers experience deep alienation , isolation and misery resulting from powerless status levels ( Marx 1848 ) . <hl>", "hl_sentences": "Marx saw workers experience deep alienation , isolation and misery resulting from powerless status levels ( Marx 1848 ) .", "question": { "cloze_format": "When Karl Marx said workers experience alienation, he meant that workers ___ .", "normal_format": "What did Karl Marx mean when he said workers experience alienation?", "question_choices": [ "must labor alone, without companionship", "do not feel connected to their work", "move from one geographical location to another", "have to put forth self-effort to get ahead" ], "question_id": "fs-id2913465", "question_text": "When Karl Marx said workers experience alienation, he meant that workers:" }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 3, "ans_text": "get rich while workers stay poor" }, "bloom": "1", "hl_context": "<hl> Today , while working conditions have improved , conflict theorists believe that the strained working relationship between employers and employees still exists . <hl> <hl> Capitalists own the means of production , and a system is in place to make business owners rich and keep workers poor . <hl> According to conflict theorists , the resulting stratification creates class conflict .", "hl_sentences": "Today , while working conditions have improved , conflict theorists believe that the strained working relationship between employers and employees still exists . Capitalists own the means of production , and a system is in place to make business owners rich and keep workers poor .", "question": { "cloze_format": "Conflict theorists view capitalists as those who ___ .", "normal_format": "Conflict theorists view who as capitalists?", "question_choices": [ "are ambitious", "fund social services", "spend money wisely", "get rich while workers stay poor" ], "question_id": "fs-id1950378", "question_text": "Conflict theorists view capitalists as those who:" }, "references_are_paraphrase": 0 } ]
9
9.1 What Is Social Stratification? In the opening story, two siblings chose different life paths. Michael stayed within his parents’ social realm, achieving similar levels of education, occupation, and income. He retained social ties with community members. Lisa, however, rose from her parents’ social position, achieving higher levels of education, occupation, and income. She broke old social ties and formed new ties, disregarding barriers and norms of race, gender, and class. Despite their different paths, both siblings were influenced by the social position of their parents. What determines a person’s social standing? And how does social standing direct or limit a person’s choices? Sociologists use the term social stratification to describe the system of social standing. Social stratification refers to a society’s categorization of its people into rankings of socioeconomic tiers based on factors like wealth, income, race, education, and power. You may remember the word “stratification” from geology class. The distinct vertical layers found in rock, called stratification, are a good way to visualize social structure. Society’s layers are made of people, and society’s resources are distributed unevenly throughout the layers. The people who have more resources represent the top layer of the social structure of stratification. Other groups of people, with progressively fewer and fewer resources, represent the lower layers of our society. In the United States, people like to believe everyone has an equal chance at success. To a certain extent, Michael and Lisa illustrate the belief that hard work and talent—not prejudicial treatment or societal values—determine social rank. This emphasis on self-effort perpetuates the belief that people control their own social standing. However, sociologists recognize that social stratification is a society-wide system that makes inequalities apparent. While there are always inequalities between individuals, sociologists are interested in larger social patterns. Stratification is not about individual inequalities, but about systematic inequalities based on group membership, classes, and the like. No individual, rich or poor, can be blamed for social inequalities. A person’s social standing is affected by the structure of society. Although individuals may support or fight inequalities, social stratification is created and supported by society as a whole. Factors that define stratification vary in different societies. In most societies, stratification is an economic system, based on wealth , the net value of money and assets a person has, and income , a person’s wages or investment dividends. While people are regularly categorized based on how rich or poor they are, other important factors influence social standing. For example, in some cultures, wisdom and charisma are valued, and people who have them are revered more than those who don’t. In some cultures, the elderly are esteemed; in others, the elderly are disparaged or overlooked. Societies’ cultural beliefs often reinforce the inequalities of stratification. One key determinant of social standing is the social standing of one’s parents. Parents tend to pass their social position on to their children. People inherit not only social standing but also the cultural norms that accompany a certain lifestyle. They share these with a network of friends and family members. Social standing becomes a comfort zone, a familiar lifestyle, and an identity. Other determinants are found in a society’s occupational structure. Teachers, for example, often have high levels of education but receive relatively low pay. Many believe that teaching is a noble profession, so teachers should do their jobs for love of their profession and the good of their students, not for money. Yet no successful executive or entrepreneur would embrace that attitude in the business world, where profits are valued as a driving force. Cultural attitudes and beliefs like these support and perpetuate social inequalities. Systems of Stratification Sociologists distinguish between two types of systems of stratification. Closed systems accommodate little change in social position. They do not allow people to shift levels and do not permit social relations between levels. Open systems, which are based on achievement, allow movement and interaction between layers and classes. Different systems reflect, emphasize, and foster certain cultural values, and shape individual beliefs. Stratification systems include class systems and caste systems, as well as meritocracy. The Caste System Caste systems are closed stratification systems in which people can do little or nothing to change their social standing. A caste system is one in which people are born into their social standing and will remain in it their whole lives. People are assigned occupations regardless of their talents, interests, or potential. There are virtually no opportunities to improve one’s social position. In the Hindu caste tradition, people were expected to work in the occupation of their caste and to enter into marriage according to their caste. Accepting this social standing was considered a moral duty. Cultural values reinforced the system. Caste systems promote beliefs in fate, destiny, and the will of a higher power, rather than promoting individual freedom as a value. A person who lived in a caste society was socialized to accept his or her social standing. Although the caste system in India has been officially dismantled, its residual presence in Indian society is deeply embedded. In rural areas, aspects of the tradition are more likely to remain, while urban centers show less evidence of this past. In India’s larger cities, people now have more opportunities to choose their own career paths and marriage partners. As a global center of employment, corporations have introduced merit-based hiring and employment to the nation. The Class System A class system is based on both social factors and individual achievement. A class consists of a set of people who share similar status with regard to factors like wealth, income, education, and occupation. Unlike caste systems, class systems are open. People are free to gain a different level of education or employment than their parents. They can also socialize with and marry members of other classes, allowing people to move from one class to another. In a class system, occupation is not fixed at birth. Though family and other societal models help guide a person toward a career, personal choice plays a role. Michael, the sibling in the chapter opening, chose a career similar to that of his parents. His sister Lisa chose a career based on individual interests that differed from her parents’ social class. In class systems, people have the option to form exogamous marriages, unions of spouses from different social categories. Marriage in these circumstances is based on values such as love and compatibility rather than on social standing or economics. Though social conformities still exist that encourage people to choose partners within their own class, people are not as pressured to choose marriage partners based solely on those elements. For example, although Michael formed an endogamous union, marrying a partner from his same social background, Lisa formed an exogamous union, marrying someone outside her social categories. Meritocracy Meritocracy is another system of social stratification in which personal effort—or merit—determines social standing. High levels of effort will lead to a high social position, and vice versa. The concept of meritocracy is an ideal—that is, a society has never existed where social rank was based purely on merit. Because of the complex structure of societies, processes like socialization, and the realities of economic systems, social standing is influenced by multiple factors, not merit alone. Inheritance and pressure to conform to norms, for instance, disrupt the notion of a pure meritocracy. Sociologists see aspects of meritocracies in modern societies when they study the role of academic performance and job performance, and the systems in place for evaluating and rewarding achievement in these areas. Status Consistency Social stratification systems determine social position based on factors like income, education, and occupation. Sociologists use the term status consistency to describe the consistency, or lack thereof, of an individual’s rank across these factors. Caste systems correlate with high status consistency, whereas the more flexible class system has lower status consistency. To illustrate, let’s consider Susan. Susan earned her high school degree but did not go on to college. That factor is a trait of the lower-middle class. She began doing landscaping work, which, as manual labor, is also a trait of lower-middle or even lower class. However, over time, Susan started her own company. She hired employees. She won larger contracts. She became a business owner and earned a lot of money. Those traits represent the upper-middle class. Here there are inconsistencies between Susan’s educational level, her occupation, and her income. In a class system, a person can work hard and have little education and still be in middle or upper class, whereas in a caste system that would not be possible. In a class system, low status consistency correlates with having more choices and opportunities. The Commoner Who Could Be Queen On April 29, 2011, in London, England, Prince William, Duke of Cambridge, married Catherine Middleton, a commoner. It is rare, though not unheard of, for a member of the British royal family to marry a commoner. Kate Middleton had a middle-class upbringing. Her father was a former flight dispatcher and her mother a former flight attendant. Kate and William met when they were both students at the University of St. Andrews in Scotland (Köhler 2010). Britain’s monarchy arose during the Middle Ages. Its social hierarchy placed royalty at the top and commoners on the bottom. This was generally a closed system, with people born into positions of nobility. Wealth was passed from generation to generation through primogeniture , a law stating that all property would be inherited by the firstborn son. If the family had no son, the land went to the next closest male relation. Women could not inherit property and their social standing was primarily determined through marriage. The arrival of the Industrial Revolution changed Britain’s social structure. Commoners moved to cities, got jobs, and made better livings. Gradually, people found new opportunities to increase their wealth and power. Today, the government is a constitutional monarchy with the prime minister and other ministers elected to their positions, and with the royal family’s role being largely ceremonial. The long-ago differences between nobility and commoners have blurred, and the modern class system in Britain is similar to that of the United States (McKee 1996). Today, the royal family still commands wealth, power, and a great deal of attention. When Queen Elizabeth II retires or passes away, Prince Charles will be first in line to ascend the throne. If he abdicates (chooses not to become king) or dies, the position will go to Prince William. If that happens, Kate Middleton will be called Queen Catherine and hold the position of queen consort. She will be one of the few queens in history to have earned a college degree (Marquand 2011). There is a great deal of social pressure on her not only to behave as a royal but to bear children. The royal family recently changed its succession laws to allow daughters, not just sons, to ascend the throne. Kate’s experience—from commoner to possible queen—demonstrates the fluidity of social position in modern society. 9.2 Social Stratification and Mobility in the United States Most sociologists define social class as a grouping based on similar social factors like wealth, income, education, and occupation. These factors affect how much power and prestige a person has. Social stratification reflects an unequal distribution of resources. In most cases, having more money means having more power or more opportunities. Stratification can also result from physical and intellectual traits. Categories that affect social standing include family ancestry, race, ethnicity, age, and gender. In the United States, standing can also be defined by characteristics such as IQ, athletic abilities, appearance, personal skills, and achievements. Standard of Living In the last century, the United States has seen a steady rise in its standard of living , the level of wealth available to a certain socioeconomic class in order to acquire the material necessities and comforts to maintain its lifestyle. The standard of living is based on factors such as income, employment, class, poverty rates, and affordability of housing. Because standard of living is closely related to quality of life, it can represent factors such as the ability to afford a home, own a car, and take vacations. In the United States, a small portion of the population has the means to the highest standard of living. A Federal Reserve Bank study in 2009 showed that a mere one percent of the population holds one third of our nation’s wealth (Kennickell 2009). Wealthy people receive the most schooling, have better health, and consume the most goods and services. Wealthy people also wield decision-making power. Many people think of the United States as a “middle-class society.” They think a few people are rich, a few are poor, and most are pretty well off, existing in the middle of the social strata. But as the study above indicates, there is not an even distribution of wealth. Millions of women and men struggle to pay rent, buy food, find work, and afford basic medical care. In the United States, as in most high-income nations, social stratifications and standards of living are in part based on occupation (Lin and Xie 1988). Aside from the obvious impact that income has on someone’s standard of living, occupations also influence social standing through the relative levels of prestige they afford. Employment in medicine, law, or engineering confers high status. Teachers and police officers are generally respected, though not considered particularly prestigious. On the other end of the scale, some of the lowest rankings apply to positions like waitress, janitor, and bus driver. Social Classes in the United States Does a person’s appearance indicate class? Can you tell a man’s education level based on his clothing? Do you know a woman’s income by the car she drives? There may have been a time in the United States when people’s class was more visibly apparent. Today, however, it is harder to determine class. For sociologists, too, categorizing class is a fluid science. Sociologists general identify three levels of class in the United States: upper, middle, and lower class. Within each class, there are many subcategories. Wealth is the most significant way of distinguishing classes, because wealth can be transferred to one’s children, perpetuating the class structure. One economist, J.D. Foster, defines the 20 percent of America’s highest earners as “upper income,” and the lower 20 percent as “lower income.” The remaining 60 percent of the population make up the middle class. But by that distinction, annual household incomes for the middle class range between $25,000 and $100,000 (Mason and Sullivan 2010). How can a person earning $25,000 a year have the same standing as someone earning $100,000 a year—four times as much? One sociological perspective distinguishes the classes, in part, according to their relative power and control over their lives. The upper class not only have power and control over their own lives, their social status gives them power and control over others’ lives as well. The middle class don’t generally control other strata of society, but they do exert control over their own lives. In contrast, the lower class has little control over their work or lives. Below, we will explore the major divisions of American social class and their key subcategories. Upper Class The upper class is considered America’s top, and only the powerful elite get to see the view from there. In the United States, people with extreme wealth make up one percent of the population, and they own one-third of the country’s wealth (Beeghley 2008). Money provides not just access to material goods, but also access to power. America’s upper class wields a lot of power. As corporate leaders, their decisions affect the job status of millions of people. As media owners, they shape the collective identity of the nation. They run the major network television stations, radio broadcasts, newspapers, magazines, publishing houses, and sports franchises. As board members of the most influential colleges and universities, they shape cultural attitudes and values. As philanthropists, they establish foundations to support social causes they believe in. As campaign contributors, they influence politicians and fund campaigns, sometimes to protect their own economic interests. American society has historically distinguished between “old money” (inherited wealth passed from one generation to the next) and “new money” (wealth you have earned and built yourself). While both types may have equal net worth, they have traditionally held different social standing. People of old money, firmly situated in the upper class for generations, have held high prestige. Their families have socialized them to know the customs, norms, and expectations that come with wealth. Often, the very wealthy don’t work for wages. Some study business or become lawyers in order to manage the family fortune. Others, such as Paris Hilton, capitalize on being a rich socialite and transform that into celebrity status, flaunting a wealthy lifestyle. However, new money members of the upper class are not oriented to the customs and mores of the elite. They haven’t gone to the most exclusive schools. They have not established old-money social ties. People with new money might flaunt their wealth, buying sports cars and mansions, but they might still exhibit behaviors attributed to the middle and lower classes. The Middle Class Many people call themselves middle class, but there are differing ideas about what that means. People with annual incomes of $150,000 call themselves middle class, as do people who annually earn $30,000. That helps explain why, in the United States, the middle class is broken into upper and lower subcategories. Upper-middle-class people tend to hold bachelor’s and postgraduate degrees. They’ve studied subjects such as business, management, law, or medicine. Lower-middle-class members hold bachelor’s degrees or associate’s degrees from two-year community or technical colleges. Comfort is a key concept to the middle class. Middle-class people work hard and live fairly comfortable lives. Upper-middle-class people tend to pursue careers that earn comfortable incomes. They provide their families with large homes and nice cars. They may go skiing or boating on vacation. Their children receive quality education and health care (Gilbert 2010). In the lower middle class, people hold jobs supervised by members of the upper middle class. They fill technical, lower-level management, or administrative support positions. Compared to lower-class work, lower-middle-class jobs carry more prestige and come with slightly higher paychecks. With these incomes, people can afford a decent, mainstream lifestyle, but they struggle to maintain it. They generally don’t have enough income to build significant savings. In addition, their grip on class status is more precarious than in the upper tiers of the class system. When budgets are tight, lower-middle-class people are often the ones to lose their jobs. The Lower Class The lower class is also referred to as the working class. Just like the middle and upper classes, the lower class can be divided into subsets: the working class, the working poor, and the underclass. Compared to the lower middle class, lower-class people have less of an educational background and earn smaller incomes. They work jobs that require little prior skill or experience, often doing routine tasks under close supervision. Working-class people, the highest subcategory of the lower class, often land decent jobs in fields like custodial or food service. The work is hands-on and often physically demanding, such as landscaping, cooking, cleaning, or building. Beneath the working class is the working poor. Like the working class, they have unskilled, low-paying employment. However, their jobs rarely offer benefits such as healthcare or retirement planning, and their positions are often seasonal or temporary. They work as sharecroppers, migrant farm workers, housecleaners, and day laborers. Some are high school dropouts. Some are illiterate, unable to read job ads. Many do not vote because they do not believe that any politician will help change their situation (Beeghley 2008). How can people work full time and still be poor? Even working full time, millions of the working poor earn incomes too meager to support a family. Minimum wage varies from state to state, but in many states it is $7.25 (Department of Labor 2011). At that rate, working 40 hours a week earns $290. That comes to $15,080 a year, before tax and deductions. Even for a single person, the pay is low. A married couple with children will have a hard time covering expenses. The underclass is America’s lowest tier. Members of the underclass live mainly in inner cities. Many are unemployed or underemployed. Those who do hold jobs typically perform menial tasks for little pay. Some of the underclass are homeless. For many, welfare systems provide a much-needed support through food assistance, medical care, housing, and the like. Social Mobility Social mobility refers to the ability to change positions within a social stratification system. When people improve or diminish their economic status in a way that affects social class, they experience social mobility. Upward mobility refers to an increase—or upward shift—in social class. In the United States, people applaud the rags-to-riches achievements of celebrities like Jennifer Lopez or Michael Jordan. Bestselling author Stephen King worked as a janitor prior to being published. Oprah Winfrey grew up in poverty in rural Mississippi before becoming a powerful media personality. There are many stories of people rising from modest beginnings to fame and fortune. But the truth is that relative to the overall population, the number of people who launch from poverty to wealth is very small. Still, upward mobility is not only about becoming rich and famous. In the United States, people who earn a college degree, get a job promotion, or marry someone with a good income may move up socially. Downward mobility indicates a lowering of one’s social class. Some people move downward because of business setbacks, unemployment, or illness. Dropping out of school, losing a job, or becoming divorced may result in a loss of income or status and, therefore, downward social mobility. Intergenerational mobility explains a difference in social class between different generations of a family. For example, an upper-class executive may have parents who belonged to the middle class. In turn, those parents may have been raised in the lower class. Patterns of intergenerational mobility can reflect long-term societal changes. Intragenerational mobility describes a difference in social class that between different members of the same generation. For example, the wealth and prestige experienced by one person may be quite different from that of his or her siblings. Structural mobility happens when societal changes enable a whole group of people to move up or down the social class ladder. Structural mobility is attributable to changes in society as a whole, not individual changes. In the first half of the 20th century, industrialization expanded the U.S. economy, raising the standard of living and leading to upward structural mobility. In today’s work economy, the recession and the outsourcing of jobs overseas have contributed to high unemployment rates. Many people have experienced economic setbacks, creating a wave of downward structural mobility. Many Americans believe that people move up in class because of individual efforts and move down by their own doing. In the example of the siblings Michael and Lisa, Lisa may have had more intelligence, drive, and ambition than her brother. She may have worked harder. However, Lisa’s story can also be explained in the context of structural mobility. Lisa grew up during a time of expanding opportunities for women, opportunities that were not so readily available to her mother. She may have felt encouraged by her college mentors to pursue a higher degree, and she may have felt rewarded when she did so. If Michael and Lisa had grown up in an earlier era, their life paths may have been completely different. When analyzing the trends and movements in social mobility, sociologists consider all modes of mobility. Scholars recognize that mobility is not as common or easy to achieve as many people think. In fact, some consider social mobility a myth. Class Traits Class traits , also called class markers, are the typical behaviors, customs, and norms that define each class. Class traits indicate the level of exposure a person has to a wide range of cultures. Class traits also indicate the amount of resources a person has to spend on items like hobbies, vacations, and leisure activities. People may associate the upper class with enjoyment of costly, refined, or highly cultivated tastes—expensive clothing, luxury cars, high-end fund-raisers, and opulent vacations. People may also believe that the middle and lower classes are more likely to enjoy camping, fishing, or hunting, shopping at large retailers, and participating in community activities. It is important to note that while these descriptions may be class traits, they may also simply be stereotypes. Moreover, just as class distinctions have blurred in recent decades, so too have class traits. A very wealthy person may enjoy bowling as much as opera. A factory worker could be a skilled French cook. A billionaire might dress in ripped jeans, and a low-income student might own designer shoes. These days, individual taste does not necessarily follow class lines. Still, you are not likely to see someone driving a Mercedes living in an inner-city neighborhood. And most likely, a resident of a wealthy gated community will not be riding a bicycle to work. Class traits often develop based on cultural behaviors that stem from the resources available within each class. Sociological Research Turn-of-the-Century “Social Problem Novels”: Sociological Gold Mines Class distinctions were sharper in the 19th century and earlier, in part because people easily accepted them. The ideology of social order made class structure seem natural, right, and just. In the late 19th and early 20th centuries, American and British novelists played a role in changing public perception. They published novels in which characters struggled to survive against a merciless class system. These dissenting authors used gender and morality to question the class system and expose its inequalities. They protested the suffering of urbanization and industrialization, drawing attention to these issues. These “social problem novels,” sometimes called Victorian realism, forced middle-class readers into an uncomfortable position: they had to question and challenge the natural order of social class. For speaking out so strongly about the social issues of class, authors were both praised and criticized. Most authors did not want to dissolve the class system. They wanted to bring about an awareness that would improve conditions for the lower classes, while maintaining their own higher class positions (DeVine 2005). Soon, middle-class readers were not their only audience. In 1870, Forster’s Elementary Education Act required all children ages 5 through 12 in England and Wales to attend school. The act increased literacy levels among the urban poor, causing a rise in sales of cheap newspapers and magazines. Additionally, the increasing number of people who rode public transit systems created a demand for “railway literature,” as it was called (Williams 1984). These reading materials are credited with the move toward democratization in England. By 1900 the British middle class established a rigid definition for itself, and England’s working class also began to self-identify and demand a better way of life. Many of the novels of that era are seen as sociological goldmines. They are studied as existing sources because they detail the customs and mores of the upper, middle, and lower classes of that period in history. Examples of “social problem” novels include Charles Dickens’s The Adventures of Oliver Twist (1838), which shocked readers with its brutal portrayal of the realities of poverty, vice, and crime. Thomas Hardy’s Tess of the d’Urbervilles (1891) was considered revolutionary by critics for its depiction of working-class women (DeVine 2005), and American novelist Theodore Dreiser’s Sister Carrie (1900) portrayed an accurate and detailed description of early Chicago. 9.3 Global Stratification and Inequality Global stratification compares the wealth, economic stability, status, and power of countries across the world. Global stratification highlights worldwide patterns of social inequality. In the early years of civilization, hunter-gatherer and agrarian societies lived off the earth, rarely interacting with other societies. When explorers began traveling, societies began trading goods, as well as ideas and customs. In the 19th century, the Industrial Revolution created unprecedented wealth in Western Europe and North America. Due to mechanical inventions and new means of production, people began working in factories—not only men, but women and children as well. By the late 19th and early 20th centuries, industrial technology had gradually raised the standard of living for many people in the United States and Europe. The Industrial Revolution also saw the rise of vast inequalities between countries that were industrialized and those that were not. As some nations embraced technology and saw increased wealth and goods, others maintained their ways; as the gap widened, the nonindustrialized nations fell further behind. Some social researchers, such as Walt Rostow, suggest that the disparity also resulted from power differences. Applying a conflict theory perspective, he asserts that industrializing nations took advantage of the resources of traditional nations. As industrialized nations became rich, other nations became poor (Rostow 1960). Sociologists studying global stratification analyze economic comparisons between nations. Income, purchasing power, and wealth are used to calculate global stratification. Global stratification also compares the quality of life that a country’s population can have. Poverty levels have been shown to vary greatly. The poor in wealthy countries like the United States or Europe are much better off than the poor in less-industrialized countries such as Mali or India. In 2002 the UN implemented the Millennium Project, an attempt to cut poverty worldwide by the year 2015. To reach the project’s goal, planners in 2006 estimated that industrialized nations must set aside 0.7 percent of their gross national income—the total value of the nation’s good and service, plus or minus income received from and sent to other nations—to aid in developing countries (Landler and Sanger, 2009; Millennium Project 2006). Models of Global Stratification Various models of global stratification all have one thing in common: they rank countries according to their relative economic status, or gross national product (GNP). Traditional models, now considered outdated, used labels to describe the stratification of the different areas of the world. Simply put, they were named “first world, “second world,” and “third world.” First and second world described industrialized nations, while third world referred to “undeveloped” countries (Henslin 2004). When researching existing historical sources, you may still encounter these terms, and even today people still refer to some nations as the “third world.” Another model separates countries into two groups: more developed and less developed. More developed nations have higher wealth, such as Canada, Japan, and Australia. Less developed nations have less wealth to distribute among higher populations, including many countries in central Africa, South America, and some island nations. Yet another system of global classification defines countries based on the per capita gross domestic product (GDP), a country’s average national wealth per person. The GDP is calculated (usually annually) one of two ways: by totaling either the income of all citizens or the value of all goods and services produced in the country during the year. It also includes government spending. Because the GDP indicates a country’s productivity and performance, comparing GDP rates helps establish a country’s economic health in relation to other countries. The figures also establish a country’s standard of living. According to this analysis, a GDP standard of a middle-income nation represents a global average. In low-income countries, most people are poor relative to people in other countries. Citizens have little access to amenities such as electricity, plumbing, and clean water. People in low-income countries are not guaranteed education, and many are illiterate. The life expectancy of citizens is lower than in high-income countries. Big Picture The Big Picture: Calculating Global Stratification A few organizations take on the job of comparing the wealth of nations. The Population Reference Bureau (PRB) is one of them. Besides a focus on population data, the PRB publishes an annual report that measures the relative economic well-being of all the world’s countries. It’s called the GNI PPP. GNI, or gross national income, measures the current value of goods and services produced by a country. PPP, or purchasing power parity, measures the relative power a country has to purchase those same goods and services. So, GNI refers to productive output and PPP refers to buying power. The total figure is divided by the number of residents living in a country to establish the average income of a resident of that country. Because costs of goods and services vary from one country to the next, the GNI PPP converts figures into a relative international unit. Calculating GNI PPP figures helps researchers accurately compare countries’ standard of living. They allow the United Nations and Population Reference Bureau to compare and rank the wealth of all countries and consider international stratification issues (nationsonline.org). 9.4 Theoretical Perspectives on Social Stratification Basketball is one of the highest-paying professional sports. There is stratification even among teams. For example, the Minnesota Timberwolves hand out the lowest annual payroll, while the Los Angeles Lakers reportedly pay the highest. Kobe Bryant, a Lakers shooting guard, is one of the highest paid athletes in the NBA, earning around $25 million a year (Basketballreference.com 2011). Even within specific fields, layers are stratified and members are ranked. In sociology, even an issue such as NBA salaries can be seen from various points of view. Functionalists will examine the purpose of such high salaries, while conflict theorists will study the exorbitant salaries as an unfair distribution of money. Social stratification takes on new meanings when it is examined from different sociological perspectives—functionalism, conflict theory, and symbolic interactionism. Functionalism In sociology, the functionalist perspective examines how society’s parts operate. According to functionalism, different aspects of society exist because they serve a needed purpose. What is the function of social stratification? In 1945, sociologists Kingsley Davis and Wilbert Moore published the Davis-Moore thesis , which argued that the greater the functional importance of a social role, the greater must be the reward. The theory posits that social stratification represents the inherently unequal value of different work. Certain tasks in society are more valuable than others. Qualified people who fill those positions must be rewarded more than others. According to Davis and Moore, a firefighter’s job is more important than, for instance, a grocery store cashier’s. The cashier position does not require the same skill and training level as firefighting. Without the incentive of higher pay and better benefits, why would someone be willing to rush into burning buildings? If pay levels were the same, the firefighter might as well work as a grocery store cashier. Davis and Moore believed that rewarding more important work with higher levels of income, prestige, and power encourages people to work harder and longer. Davis and Moore stated that, in most cases, the degree of skill required for a job determines that job’s importance. They also stated that the more skill required for a job, the fewer qualified people there would be to do that job. Certain jobs, such as cleaning hallways or answering phones, do not require much skill. The employees don’t need a college degree. Other work, like designing a highway system or delivering a baby, requires immense skill. In 1953, Melvin Tumin countered the Davis-Moore thesis in “Some Principles of Stratification: A Critical Analysis.” Tumin questioned what determined a job’s degree of importance. The Davis-Moore thesis does not explain, he argued, why a media personality with little education, skill, or talent becomes famous and rich on a reality show or a campaign trail. The thesis also does not explain inequalities in the education system, or inequalities due to race or gender. Tumin believed social stratification prevented qualified people from attempting to fill roles (Tumin 1953). For example, an underprivileged youth has less chance of becoming a scientist, no matter how smart she is, because of the relative lack of opportunity available to her. The Davis-Moore thesis, though open for debate, was an early attempt to explain why stratification exists. The thesis states that social stratification is necessary to promote excellence, productivity, and efficiency, thus giving people something to strive for. Davis and Moore believed that the system serves society as a whole because it allows everyone to benefit to a certain extent. Conflict Theory Conflict theorists are deeply critical of social stratification, asserting that it benefits only some people, not all of society. For instance, to a conflict theorist, it seems wrong that a basketball player is paid millions for an annual contract while a public school teacher earns $35,000 a year. Stratification, conflict theorists believe, perpetuates inequality. Conflict theorists try to bring awareness to inequalities, such as how a rich society can have so many poor members. Many conflict theorists draw on the work of Karl Marx. During the 19th-century era of industrialization, Marx believed social stratification resulted from people’s relationship to production. People were divided by a single line: they either owned factories or worked in them. In Marx’s time, bourgeois capitalists owned high-producing businesses, factories, and land, as they still do today. Proletariats were the workers who performed the manual labor to produce goods. Upper-class capitalists raked in profits and got rich, while working-class proletariats earned skimpy wages and struggled to survive. With such opposing interests, the two groups were divided by differences of wealth and power. Marx saw workers experience deep alienation, isolation and misery resulting from powerless status levels (Marx 1848). Today, while working conditions have improved, conflict theorists believe that the strained working relationship between employers and employees still exists. Capitalists own the means of production, and a system is in place to make business owners rich and keep workers poor. According to conflict theorists, the resulting stratification creates class conflict. Symbolic Interactionism Symbolic interactionism is a theory that uses everyday interactions of individuals to explain society as a whole. Symbolic interactionism examines stratification from a micro-level perspective. This analysis strives to explain how people’s social standing affects their everyday interactions. In most communities, people interact primarily with others who share the same social standing. It is precisely because of social stratification that people tend to live, work, and associate with others like themselves, people who share their same income level, educational background, or racial background, and even tastes in food, music, and clothing. The built-in system of social stratification groups people together. Symbolic interactionists also note that people’s appearance reflects their perceived social standing. Housing, clothing, and transportation indicate social status, as do hairstyles, taste in accessories, and personal style. Conspicuous consumption refers to buying certain products to make a social statement about status. Carrying pricey but eco-friendly water bottles could indicate a person’s social standing. Some people buy expensive trendy sneakers even though they will never wear them to jog or play sports. A $17,000 car provides transportation as easily as a $100,000 vehicle, but the luxury car makes a social statement that the less expensive car can’t live up to. All of these symbols of stratification are worthy of examination by an interactionist.
anatomy_and_physiology
Chapter Objectives After this chapter, you will be able to: Discuss both functional and structural classifications for body joints Describe the characteristic features for fibrous, cartilaginous, and synovial joints and give examples of each Define and identify the different body movements Discuss the structure of specific body joints and the movements allowed by each Explain the development of body joints Introduction The adult human body has 206 bones, and with the exception of the hyoid bone in the neck, each bone is connected to at least one other bone. Joints are the location where bones come together. Many joints allow for movement between the bones. At these joints, the articulating surfaces of the adjacent bones can move smoothly against each other. However, the bones of other joints may be joined to each other by connective tissue or cartilage. These joints are designed for stability and provide for little or no movement. Importantly, joint stability and movement are related to each other. This means that stable joints allow for little or no mobility between the adjacent bones. Conversely, joints that provide the most movement between bones are the least stable. Understanding the relationship between joint structure and function will help to explain why particular types of joints are found in certain areas of the body. The articulating surfaces of bones at stable types of joints, with little or no mobility, are strongly united to each other. For example, most of the joints of the skull are held together by fibrous connective tissue and do not allow for movement between the adjacent bones. This lack of mobility is important, because the skull bones serve to protect the brain. Similarly, other joints united by fibrous connective tissue allow for very little movement, which provides stability and weight-bearing support for the body. For example, the tibia and fibula of the leg are tightly united to give stability to the body when standing. At other joints, the bones are held together by cartilage, which permits limited movements between the bones. Thus, the joints of the vertebral column only allow for small movements between adjacent vertebrae, but when added together, these movements provide the flexibility that allows your body to twist, or bend to the front, back, or side. In contrast, at joints that allow for wide ranges of motion, the articulating surfaces of the bones are not directly united to each other. Instead, these surfaces are enclosed within a space filled with lubricating fluid, which allows the bones to move smoothly against each other. These joints provide greater mobility, but since the bones are free to move in relation to each other, the joint is less stable. Most of the joints between the bones of the appendicular skeleton are this freely moveable type of joint. These joints allow the muscles of the body to pull on a bone and thereby produce movement of that body region. Your ability to kick a soccer ball, pick up a fork, and dance the tango depend on mobility at these types of joints.
[ { "answer": { "ans_choice": 2, "ans_text": "amphiarthrosis" }, "bloom": "1", "hl_context": "<hl> An amphiarthrosis is a joint that has limited mobility . <hl> <hl> An example of this type of joint is the cartilaginous joint that unites the bodies of adjacent vertebrae . <hl> <hl> Filling the gap between the vertebrae is a thick pad of fibrocartilage called an intervertebral disc ( Figure 9.3 ) . <hl> Each intervertebral disc strongly unites the vertebrae but still allows for a limited amount of movement between them . However , the small movements available between adjacent vertebrae can sum together along the length of the vertebral column to provide for large ranges of body movements .", "hl_sentences": "An amphiarthrosis is a joint that has limited mobility . An example of this type of joint is the cartilaginous joint that unites the bodies of adjacent vertebrae . Filling the gap between the vertebrae is a thick pad of fibrocartilage called an intervertebral disc ( Figure 9.3 ) .", "question": { "cloze_format": "The joint between adjacent vertebrae that includes an invertebral disc is classified as ___ .", "normal_format": "The joint between adjacent vertebrae that includes an invertebral disc is classified as which type of joint?", "question_choices": [ "diarthrosis", "multiaxial", "amphiarthrosis", "synarthrosis" ], "question_id": "fs-id1476098", "question_text": "The joint between adjacent vertebrae that includes an invertebral disc is classified as which type of joint?" }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 1, "ans_text": "the manubriosternal joint" }, "bloom": "1", "hl_context": "<hl> An immobile or nearly immobile joint is called a synarthrosis . <hl> The immobile nature of these joints provide for a strong union between the articulating bones . This is important at locations where the bones provide protection for internal organs . <hl> Examples include sutures , the fibrous joints between the bones of the skull that surround and protect the brain ( Figure 9.2 ) , and the manubriosternal joint , the cartilaginous joint that unites the manubrium and body of the sternum for protection of the heart . <hl>", "hl_sentences": "An immobile or nearly immobile joint is called a synarthrosis . Examples include sutures , the fibrous joints between the bones of the skull that surround and protect the brain ( Figure 9.2 ) , and the manubriosternal joint , the cartilaginous joint that unites the manubrium and body of the sternum for protection of the heart .", "question": { "cloze_format": "The joint that is classified as a synarthrosis is ___ .", "normal_format": "Which of these joints is classified as a synarthrosis?", "question_choices": [ "the pubic symphysis", "the manubriosternal joint", "an invertebral disc", "the shoulder joint" ], "question_id": "fs-id2303902", "question_text": "Which of these joints is classified as a synarthrosis?" }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 0, "ans_text": "the metacarpophalangeal joint" }, "bloom": "1", "hl_context": "A freely mobile joint is classified as a diarthrosis . These types of joints include all synovial joints of the body , which provide the majority of body movements . Most diarthrotic joints are found in the appendicular skeleton and thus give the limbs a wide range of motion . These joints are divided into three categories , based on the number of axes of motion provided by each . An axis in anatomy is described as the movements in reference to the three anatomical planes : transverse , frontal , and sagittal . <hl> Thus , diarthroses are classified as uniaxial ( for movement in one plane ) , biaxial ( for movement in two planes ) , or multiaxial joints ( for movement in all three anatomical planes ) . <hl> A uniaxial joint only allows for a motion in a single plane ( around a single axis ) . The elbow joint , which only allows for bending or straightening , is an example of a uniaxial joint . <hl> A biaxial joint allows for motions within two planes . <hl> <hl> An example of a biaxial joint is a metacarpophalangeal joint ( knuckle joint ) of the hand . <hl> The joint allows for movement along one axis to produce bending or straightening of the finger , and movement along a second axis , which allows for spreading of the fingers away from each other and bringing them together . A joint that allows for the several directions of movement is called a multiaxial joint ( polyaxial or triaxial joint ) . This type of diarthrotic joint allows for movement along three axes ( Figure 9.4 ) . The shoulder and hip joints are multiaxial joints . They allow the upper or lower limb to move in an anterior-posterior direction and a medial-lateral direction . In addition , the limb can also be rotated around its long axis . This third movement results in rotation of the limb so that its anterior surface is moved either toward or away from the midline of the body . 9.2 Fibrous Joints Learning Objectives By the end of this section , you will be able to :", "hl_sentences": "Thus , diarthroses are classified as uniaxial ( for movement in one plane ) , biaxial ( for movement in two planes ) , or multiaxial joints ( for movement in all three anatomical planes ) . A biaxial joint allows for motions within two planes . An example of a biaxial joint is a metacarpophalangeal joint ( knuckle joint ) of the hand .", "question": { "cloze_format": "The joint that is classified as a biaxial diarthrosis is ___ .", "normal_format": "Which of these joints is classified as a biaxial diarthrosis?", "question_choices": [ "the metacarpophalangeal joint", "the hip joint", "the elbow joint", "the pubic symphysis" ], "question_id": "fs-id1927730", "question_text": "Which of these joints is classified as a biaxial diarthrosis?" }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 3, "ans_text": "are joints where the bones articulate with each other within a fluid-filled joint cavity" }, "bloom": "1", "hl_context": "The structural classification of joints is based on whether the articulating surfaces of the adjacent bones are directly connected by fibrous connective tissue or cartilage , or whether the articulating surfaces contact each other within a fluid-filled joint cavity . These differences serve to divide the joints of the body into three structural classifications . A fibrous joint is where the adjacent bones are united by fibrous connective tissue . At a cartilaginous joint , the bones are joined by hyaline cartilage or fibrocartilage . <hl> At a synovial joint , the articulating surfaces of the bones are not directly connected , but instead come into contact with each other within a joint cavity that is filled with a lubricating fluid . <hl> Synovial joints allow for free movement between the bones and are the most common joints of the body .", "hl_sentences": "At a synovial joint , the articulating surfaces of the bones are not directly connected , but instead come into contact with each other within a joint cavity that is filled with a lubricating fluid .", "question": { "cloze_format": "Synovial joints ________.", "normal_format": "Which of the following is correct about Synovial joints?", "question_choices": [ "may be functionally classified as a synarthrosis", "are joints where the bones are connected to each other by hyaline cartilage", "may be functionally classified as a amphiarthrosis", "are joints where the bones articulate with each other within a fluid-filled joint cavity" ], "question_id": "fs-id2226764", "question_text": "Synovial joints ________." }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 0, "ans_text": "syndesmosis" }, "bloom": "1", "hl_context": "The syndesmoses found in the forearm and leg serve to unite parallel bones and prevent their separation . However , a syndesmosis does not prevent all movement between the bones , and thus this type of fibrous joint is functionally classified as an amphiarthrosis . <hl> In the leg , the syndesmosis between the tibia and fibula strongly unites the bones , allows for little movement , and firmly locks the talus bone in place between the tibia and fibula at the ankle joint . <hl> This provides strength and stability to the leg and ankle , which are important during weight bearing . In the forearm , the interosseous membrane is flexible enough to allow for rotation of the radius bone during forearm movements . Thus in contrast to the stability provided by the tibiofibular syndesmosis , the flexibility of the antebrachial interosseous membrane allows for the much greater mobility of the forearm .", "hl_sentences": "In the leg , the syndesmosis between the tibia and fibula strongly unites the bones , allows for little movement , and firmly locks the talus bone in place between the tibia and fibula at the ankle joint .", "question": { "cloze_format": "___ is the type of fibrous joint connects the tibia and fibula.", "normal_format": "Which type of fibrous joint connects the tibia and fibula?", "question_choices": [ "syndesmosis", "symphysis", "suture", "gomphosis" ], "question_id": "fs-id2242062", "question_text": "Which type of fibrous joint connects the tibia and fibula?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 0, "ans_text": "the interosseous membrane of the forearm" }, "bloom": "1", "hl_context": "At a fibrous joint , the adjacent bones are directly connected to each other by fibrous connective tissue , and thus the bones do not have a joint cavity between them ( Figure 9.5 ) . The gap between the bones may be narrow or wide . There are three types of fibrous joints . A suture is the narrow fibrous joint found between most bones of the skull . <hl> At a syndesmosis joint , the bones are more widely separated but are held together by a narrow band of fibrous connective tissue called a ligament or a wide sheet of connective tissue called an interosseous membrane . <hl> <hl> This type of fibrous joint is found between the shaft regions of the long bones in the forearm and in the leg . <hl> Lastly , a gomphosis is the narrow fibrous joint between the roots of a tooth and the bony socket in the jaw into which the tooth fits .", "hl_sentences": "At a syndesmosis joint , the bones are more widely separated but are held together by a narrow band of fibrous connective tissue called a ligament or a wide sheet of connective tissue called an interosseous membrane . This type of fibrous joint is found between the shaft regions of the long bones in the forearm and in the leg .", "question": { "cloze_format": "An example of a wide fibrous joint is ________.", "normal_format": "Which is an example of a wide fibrous joint?", "question_choices": [ "the interosseous membrane of the forearm", "a gomphosis", "a suture joint", "a synostosis" ], "question_id": "fs-id1374760", "question_text": "An example of a wide fibrous joint is ________." }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 3, "ans_text": "anchors a tooth to the jaw" }, "bloom": "1", "hl_context": "<hl> A gomphosis ( “ fastened with bolts ” ) is the specialized fibrous joint that anchors the root of a tooth into its bony socket within the maxillary bone ( upper jaw ) or mandible bone ( lower jaw ) of the skull . <hl> A gomphosis is also known as a peg-and-socket joint . Spanning between the bony walls of the socket and the root of the tooth are numerous short bands of dense connective tissue , each of which is called a periodontal ligament ( see Figure 9.5 c ) . Due to the immobility of a gomphosis , this type of joint is functionally classified as a synarthrosis . 9.3 Cartilaginous Joints Learning Objectives By the end of this section , you will be able to :", "hl_sentences": "A gomphosis ( “ fastened with bolts ” ) is the specialized fibrous joint that anchors the root of a tooth into its bony socket within the maxillary bone ( upper jaw ) or mandible bone ( lower jaw ) of the skull .", "question": { "cloze_format": "A gomphosis ________.", "normal_format": "Which of the following is correct about a gomphosis? ", "question_choices": [ "is formed by an interosseous membrane", "connects the tibia and fibula bones of the leg", "contains a joint cavity", "anchors a tooth to the jaw" ], "question_id": "fs-id2623907", "question_text": "A gomphosis ________." }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 2, "ans_text": "a fibrous joint that unites parallel bones" }, "bloom": "1", "hl_context": "<hl> A syndesmosis ( “ fastened with a band ” ) is a type of fibrous joint in which two parallel bones are united to each other by fibrous connective tissue . <hl> The gap between the bones may be narrow , with the bones joined by ligaments , or the gap may be wide and filled in by a broad sheet of connective tissue called an interosseous membrane .", "hl_sentences": "A syndesmosis ( “ fastened with a band ” ) is a type of fibrous joint in which two parallel bones are united to each other by fibrous connective tissue .", "question": { "cloze_format": "A syndesmosis is ________.", "normal_format": "Which of the following is correct about a syndesmosis?", "question_choices": [ "a narrow fibrous joint", "the type of joint that unites bones of the skull", "a fibrous joint that unites parallel bones", "the type of joint that anchors the teeth in the jaws" ], "question_id": "fs-id2060975", "question_text": "A syndesmosis is ________." }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 1, "ans_text": "is called a symphysis when the bones are united by fibrocartilage" }, "bloom": "1", "hl_context": "As the name indicates , at a cartilaginous joint , the adjacent bones are united by cartilage , a tough but flexible type of connective tissue . These types of joints lack a joint cavity and involve bones that are joined together by either hyaline cartilage or fibrocartilage ( Figure 9.7 ) . There are two types of cartilaginous joints . A synchondrosis is a cartilaginous joint where the bones are joined by hyaline cartilage . Also classified as a synchondrosis are places where bone is united to a cartilage structure , such as between the anterior end of a rib and the costal cartilage of the thoracic cage . <hl> The second type of cartilaginous joint is a symphysis , where the bones are joined by fibrocartilage . <hl>", "hl_sentences": "The second type of cartilaginous joint is a symphysis , where the bones are joined by fibrocartilage .", "question": { "cloze_format": "A cartilaginous joint ________.", "normal_format": "Which of the following is correct about a cartilaginous joint? ", "question_choices": [ "has a joint cavity", "is called a symphysis when the bones are united by fibrocartilage", "anchors the teeth to the jaws", "is formed by a wide sheet of fibrous connective tissue" ], "question_id": "fs-id1643864", "question_text": "A cartilaginous joint ________." }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 3, "ans_text": "found at the first sternocostal joint of the thoracic cage" }, "bloom": null, "hl_context": "<hl> Examples of permanent synchondroses are found in the thoracic cage . <hl> <hl> One example is the first sternocostal joint , where the first rib is anchored to the manubrium by its costal cartilage . <hl> ( The articulations of the remaining costal cartilages to the sternum are all synovial joints . ) Additional synchondroses are formed where the anterior end of the other 11 ribs is joined to its costal cartilage . Unlike the temporary synchondroses of the epiphyseal plate , these permanent synchondroses retain their hyaline cartilage and thus do not ossify with age . Due to the lack of movement between the bone and cartilage , both temporary and permanent synchondroses are functionally classified as a synarthrosis .", "hl_sentences": "Examples of permanent synchondroses are found in the thoracic cage . One example is the first sternocostal joint , where the first rib is anchored to the manubrium by its costal cartilage .", "question": { "cloze_format": "A synchondrosis is ________.", "normal_format": "Which of the following is correct about a synchondrosis?", "question_choices": [ "found at the pubic symphysis", "where bones are connected together with fibrocartilage", "a type of fibrous joint", "found at the first sternocostal joint of the thoracic cage" ], "question_id": "fs-id16405900", "question_text": "A synchondrosis is ________." }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 0, "ans_text": "adjacent vertebrae" }, "bloom": "4", "hl_context": "<hl> The intervertebral symphysis is a wide symphysis located between the bodies of adjacent vertebrae of the vertebral column . <hl> <hl> Here a thick pad of fibrocartilage called an intervertebral disc strongly unites the adjacent vertebrae by filling the gap between them . <hl> The width of the intervertebral symphysis is important because it allows for small movements between the adjacent vertebrae . In addition , the thick intervertebral disc provides cushioning between the vertebrae , which is important when carrying heavy objects or during high-impact activities such as running or jumping . 9.4 Synovial Joints Learning Objectives By the end of this section , you will be able to :", "hl_sentences": "The intervertebral symphysis is a wide symphysis located between the bodies of adjacent vertebrae of the vertebral column . Here a thick pad of fibrocartilage called an intervertebral disc strongly unites the adjacent vertebrae by filling the gap between them .", "question": { "cloze_format": "___ are joined by a symphysis.", "normal_format": "Which of the following are joined by a symphysis?", "question_choices": [ "adjacent vertebrae", "the first rib and the sternum", "the end and shaft of a long bone", "the radius and ulna bones" ], "question_id": "fs-id1893478", "question_text": "Which of the following are joined by a symphysis?" }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 0, "ans_text": "synchondrosis" }, "bloom": "1", "hl_context": "Visit this website to view a radiograph ( X-ray image ) of a child ’ s hand and wrist . <hl> The growing bones of child have an epiphyseal plate that forms a synchondrosis between the shaft and end of a long bone . <hl> Being less dense than bone , the area of epiphyseal cartilage is seen on this radiograph as the dark epiphyseal gaps located near the ends of the long bones , including the radius , ulna , metacarpal , and phalanx bones . Which of the bones in this image do not show an epiphyseal plate ( epiphyseal gap ) ?", "hl_sentences": "The growing bones of child have an epiphyseal plate that forms a synchondrosis between the shaft and end of a long bone .", "question": { "cloze_format": "The epiphyseal plate of a growing long bone in a child is classified as a ________.", "normal_format": "What is the epiphyseal plate of a growing long bone in a child classified as?", "question_choices": [ "synchondrosis", "synostosis", "symphysis", "syndesmosis" ], "question_id": "fs-id2307902", "question_text": "The epiphyseal plate of a growing long bone in a child is classified as a ________." }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 0, "ans_text": "ball-and-socket" }, "bloom": "1", "hl_context": "<hl> The joint with the greatest range of motion is the ball-and-socket joint . <hl> At these joints , the rounded head of one bone ( the ball ) fits into the concave articulation ( the socket ) of the adjacent bone ( see Figure 9.10 f ) . The hip joint and the glenohumeral ( shoulder ) joint are the only ball-and-socket joints of the body . At the hip joint , the head of the femur articulates with the acetabulum of the hip bone , and at the shoulder joint , the head of the humerus articulates with the glenoid cavity of the scapula .", "hl_sentences": "The joint with the greatest range of motion is the ball-and-socket joint .", "question": { "cloze_format": "The ___ joint provides the greatest range of motion.", "normal_format": "Which type of joint provides the greatest range of motion?", "question_choices": [ "ball-and-socket", "hinge", "condyloid", "plane" ], "question_id": "fs-id1548130", "question_text": "Which type of joint provides the greatest range of motion?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 1, "ans_text": "hinge joint" }, "bloom": "1", "hl_context": "In a hinge joint , the convex end of one bone articulates with the concave end of the adjoining bone ( see Figure 9.10 b ) . <hl> This type of joint allows only for bending and straightening motions along a single axis , and thus hinge joints are functionally classified as uniaxial joints . <hl> A good example is the elbow joint , with the articulation between the trochlea of the humerus and the trochlear notch of the ulna . Other hinge joints of the body include the knee , ankle , and interphalangeal joints between the phalanx bones of the fingers and toes .", "hl_sentences": "This type of joint allows only for bending and straightening motions along a single axis , and thus hinge joints are functionally classified as uniaxial joints .", "question": { "cloze_format": "The joint that allows for only uniaxial movement is the ___ .", "normal_format": "Which type of joint allows for only uniaxial movement?", "question_choices": [ "saddle joint", "hinge joint", "condyloid joint", "ball-and-socket joint" ], "question_id": "fs-id2754272", "question_text": "Which type of joint allows for only uniaxial movement?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 2, "ans_text": "a plane joint" }, "bloom": "1", "hl_context": "Watch this video to see an animation of synovial joints in action . Synovial joints are places where bones articulate with each other inside of a joint cavity . <hl> The different types of synovial joints are the ball-and-socket joint ( shoulder joint ) , hinge joint ( knee ) , pivot joint ( atlantoaxial joint , between C1 and C2 vertebrae of the neck ) , condyloid joint ( radiocarpal joint of the wrist ) , saddle joint ( first carpometacarpal joint , between the trapezium carpal bone and the first metacarpal bone , at the base of the thumb ) , and plane joint ( facet joints of vertebral column , between superior and inferior articular processes ) . <hl> Which type of synovial joint allows for the widest range of motion ?", "hl_sentences": "The different types of synovial joints are the ball-and-socket joint ( shoulder joint ) , hinge joint ( knee ) , pivot joint ( atlantoaxial joint , between C1 and C2 vertebrae of the neck ) , condyloid joint ( radiocarpal joint of the wrist ) , saddle joint ( first carpometacarpal joint , between the trapezium carpal bone and the first metacarpal bone , at the base of the thumb ) , and plane joint ( facet joints of vertebral column , between superior and inferior articular processes ) .", "question": { "cloze_format": "___ is a type of synovial joint.", "normal_format": "Which of the following is a type of synovial joint?", "question_choices": [ "a synostosis", "a suture", "a plane joint", "a synchondrosis" ], "question_id": "fs-id1479354", "question_text": "Which of the following is a type of synovial joint?" }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 2, "ans_text": "prevents friction between skin and bone, or a muscle tendon and bone" }, "bloom": "1", "hl_context": "<hl> Additional structures located outside of a synovial joint serve to prevent friction between the bones of the joint and the overlying muscle tendons or skin . <hl> <hl> A bursa ( plural = bursae ) is a thin connective tissue sac filled with lubricating liquid . <hl> <hl> They are located in regions where skin , ligaments , muscles , or muscle tendons can rub against each other , usually near a body joint ( Figure 9.9 ) . <hl> Bursae reduce friction by separating the adjacent structures , preventing them from rubbing directly against each other . Bursae are classified by their location . A subcutaneous bursa is located between the skin and an underlying bone . It allows skin to move smoothly over the bone . Examples include the prepatellar bursa located over the kneecap and the olecranon bursa at the tip of the elbow . A submuscular bursa is found between a muscle and an underlying bone , or between adjacent muscles . These prevent rubbing of the muscle during movements . A large submuscular bursa , the trochanteric bursa , is found at the lateral hip , between the greater trochanter of the femur and the overlying gluteus maximus muscle . A subtendinous bursa is found between a tendon and a bone . Examples include the subacromial bursa that protects the tendon of shoulder muscle as it passes under the acromion of the scapula , and the suprapatellar bursa that separates the tendon of the large anterior thigh muscle from the distal femur just above the knee .", "hl_sentences": "Additional structures located outside of a synovial joint serve to prevent friction between the bones of the joint and the overlying muscle tendons or skin . A bursa ( plural = bursae ) is a thin connective tissue sac filled with lubricating liquid . They are located in regions where skin , ligaments , muscles , or muscle tendons can rub against each other , usually near a body joint ( Figure 9.9 ) .", "question": { "cloze_format": "A bursa ________.", "normal_format": "Which of the following is correct about a bursa?", "question_choices": [ "surrounds a tendon at the point where the tendon crosses a joint", "secretes the lubricating fluid for a synovial joint", "prevents friction between skin and bone, or a muscle tendon and bone", "is the strong band of connective tissue that holds bones together at a synovial joint" ], "question_id": "fs-id2003022", "question_text": "A bursa ________." }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 3, "ans_text": "the joint cavity is filled with a thick, lubricating fluid" }, "bloom": "1", "hl_context": "The structural classification of joints is based on whether the articulating surfaces of the adjacent bones are directly connected by fibrous connective tissue or cartilage , or whether the articulating surfaces contact each other within a fluid-filled joint cavity . These differences serve to divide the joints of the body into three structural classifications . A fibrous joint is where the adjacent bones are united by fibrous connective tissue . At a cartilaginous joint , the bones are joined by hyaline cartilage or fibrocartilage . <hl> At a synovial joint , the articulating surfaces of the bones are not directly connected , but instead come into contact with each other within a joint cavity that is filled with a lubricating fluid . <hl> Synovial joints allow for free movement between the bones and are the most common joints of the body .", "hl_sentences": "At a synovial joint , the articulating surfaces of the bones are not directly connected , but instead come into contact with each other within a joint cavity that is filled with a lubricating fluid .", "question": { "cloze_format": "At synovial joints, ________.", "normal_format": "Which of the following is correct about Synovial joints?", "question_choices": [ "the articulating ends of the bones are directly connected by fibrous connective tissue", "the ends of the bones are enclosed within a space called a subcutaneous bursa", "intrinsic ligaments are located entirely inside of the articular capsule", "the joint cavity is filled with a thick, lubricating fluid" ], "question_id": "fs-id2096151", "question_text": "At synovial joints, ________." }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 3, "ans_text": "secretes the lubricating synovial fluid" }, "bloom": "1", "hl_context": "Friction between the bones at a synovial joint is prevented by the presence of the articular cartilage , a thin layer of hyaline cartilage that covers the entire articulating surface of each bone . However , unlike at a cartilaginous joint , the articular cartilages of each bone are not continuous with each other . Instead , the articular cartilage acts like a Teflon ® coating over the bone surface , allowing the articulating bones to move smoothly against each other without damaging the underlying bone tissue . <hl> Lining the inner surface of the articular capsule is a thin synovial membrane . <hl> <hl> The cells of this membrane secrete synovial fluid ( synovia = “ a thick fluid ” ) , a thick , slimy fluid that provides lubrication to further reduce friction between the bones of the joint . <hl> This fluid also provides nourishment to the articular cartilage , which does not contain blood vessels . The ability of the bones to move smoothly against each other within the joint cavity , and the freedom of joint movement this provides , means that each synovial joint is functionally classified as a diarthrosis . Outside of their articulating surfaces , the bones are connected together by ligaments , which are strong bands of fibrous connective tissue . These strengthen and support the joint by anchoring the bones together and preventing their separation . Ligaments allow for normal movements at a joint , but limit the range of these motions , thus preventing excessive or abnormal joint movements . Ligaments are classified based on their relationship to the fibrous articular capsule . An extrinsic ligament is located outside of the articular capsule , an intrinsic ligament is fused to or incorporated into the wall of the articular capsule , and an intracapsular ligament is located inside of the articular capsule .", "hl_sentences": "Lining the inner surface of the articular capsule is a thin synovial membrane . The cells of this membrane secrete synovial fluid ( synovia = “ a thick fluid ” ) , a thick , slimy fluid that provides lubrication to further reduce friction between the bones of the joint .", "question": { "cloze_format": "At a synovial joint, the synovial membrane ________.", "normal_format": "What does the synovial membrane do in a synovial joint?\n", "question_choices": [ "forms the fibrous connective walls of the joint cavity", "is the layer of cartilage that covers the articulating surfaces of the bones", "forms the intracapsular ligaments", "secretes the lubricating synovial fluid" ], "question_id": "fs-id2095735", "question_text": "At a synovial joint, the synovial membrane ________." }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 1, "ans_text": "include the radiocarpal joint" }, "bloom": "1", "hl_context": "<hl> At a condyloid joint ( ellipsoid joint ) , the shallow depression at the end of one bone articulates with a rounded structure from an adjacent bone or bones ( see Figure 9.10 e ) . <hl> The knuckle ( metacarpophalangeal ) joints of the hand between the distal end of a metacarpal bone and the proximal phalanx bone are condyloid joints . <hl> Another example is the radiocarpal joint of the wrist , between the shallow depression at the distal end of the radius bone and the rounded scaphoid , lunate , and triquetrum carpal bones . <hl> In this case , the articulation area has a more oval ( elliptical ) shape . Functionally , condyloid joints are biaxial joints that allow for two planes of movement . One movement involves the bending and straightening of the fingers or the anterior-posterior movements of the hand . The second movement is a side-to-side movement , which allows you to spread your fingers apart and bring them together , or to move your hand in a medial-going or lateral-going direction .", "hl_sentences": "At a condyloid joint ( ellipsoid joint ) , the shallow depression at the end of one bone articulates with a rounded structure from an adjacent bone or bones ( see Figure 9.10 e ) . Another example is the radiocarpal joint of the wrist , between the shallow depression at the distal end of the radius bone and the rounded scaphoid , lunate , and triquetrum carpal bones .", "question": { "cloze_format": "Condyloid joints ________.", "normal_format": "Which of the following is correct about condyloid joints?", "question_choices": [ "are a type of ball-and-socket joint", "include the radiocarpal joint", "are a uniaxial diarthrosis joint", "are found at the proximal radioulnar joint" ], "question_id": "fs-id2338441", "question_text": "Condyloid joints ________." }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 0, "ans_text": "a fibrocartilage pad that provides padding between bones" }, "bloom": "1", "hl_context": "<hl> Located between the articulating surfaces of the femur and tibia are two articular discs , the medial meniscus and lateral meniscus ( see Figure 9.19 b ) . <hl> <hl> Each is a C-shaped fibrocartilage structure that is thin along its inside margin and thick along the outer margin . <hl> They are attached to their tibial condyles , but do not attach to the femur . While both menisci are free to move during knee motions , the medial meniscus shows less movement because it is anchored at its outer margin to the articular capsule and tibial collateral ligament . <hl> The menisci provide padding between the bones and help to fill the gap between the round femoral condyles and flattened tibial condyles . <hl> Some areas of each meniscus lack an arterial blood supply and thus these areas heal poorly if damaged .", "hl_sentences": "Located between the articulating surfaces of the femur and tibia are two articular discs , the medial meniscus and lateral meniscus ( see Figure 9.19 b ) . Each is a C-shaped fibrocartilage structure that is thin along its inside margin and thick along the outer margin . The menisci provide padding between the bones and help to fill the gap between the round femoral condyles and flattened tibial condyles .", "question": { "cloze_format": "A meniscus is ________.", "normal_format": "Which of the following is correct about a meniscus?", "question_choices": [ "a fibrocartilage pad that provides padding between bones", "a fluid-filled space that prevents friction between a muscle tendon and underlying bone", "the articular cartilage that covers the ends of a bone at a synovial joint", "the lubricating fluid within a synovial joint" ], "question_id": "fs-id1474134", "question_text": "A meniscus is ________." }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 0, "ans_text": "lateral flexion" }, "bloom": "1", "hl_context": "In addition to being held together by the intervertebral discs , adjacent vertebrae also articulate with each other at synovial joints formed between the superior and inferior articular processes called zygapophysial joints ( facet joints ) ( see Figure 9.3 ) . These are plane joints that provide for only limited motions between the vertebrae . The orientation of the articular processes at these joints varies in different regions of the vertebral column and serves to determine the types of motions available in each vertebral region . The cervical and lumbar regions have the greatest ranges of motions . <hl> In the neck , the articular processes of cervical vertebrae are flattened and generally face upward or downward . <hl> <hl> This orientation provides the cervical vertebral column with extensive ranges of motion for flexion , extension , lateral flexion , and rotation . <hl> In the thoracic region , the downward projecting and overlapping spinous processes , along with the attached thoracic cage , greatly limit flexion , extension , and lateral flexion . However , the flattened and vertically positioned thoracic articular processes allow for the greatest range of rotation within the vertebral column . The lumbar region allows for considerable extension , flexion , and lateral flexion , but the orientation of the articular processes largely prohibits rotation .", "hl_sentences": "In the neck , the articular processes of cervical vertebrae are flattened and generally face upward or downward . This orientation provides the cervical vertebral column with extensive ranges of motion for flexion , extension , lateral flexion , and rotation .", "question": { "cloze_format": "The joints between the articular processes of adjacent vertebrae can contribute to ___.", "normal_format": "The joints between the articular processes of adjacent vertebrae can contribute to which movement?", "question_choices": [ "lateral flexion", "circumduction", "dorsiflexion", "abduction" ], "question_id": "fs-id2176080", "question_text": "The joints between the articular processes of adjacent vertebrae can contribute to which movement?" }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 2, "ans_text": "eversion" }, "bloom": "1", "hl_context": "Inversion and eversion are complex movements that involve the multiple plane joints among the tarsal bones of the posterior foot ( intertarsal joints ) and thus are not motions that take place at the ankle joint . <hl> Inversion is the turning of the foot to angle the bottom of the foot toward the midline , while eversion turns the bottom of the foot away from the midline . <hl> The foot has a greater range of inversion than eversion motion . These are important motions that help to stabilize the foot when walking or running on an uneven surface and aid in the quick side-to-side changes in direction used during active sports such as basketball , racquetball , or soccer ( see Figure 9.13 i ) .", "hl_sentences": "Inversion is the turning of the foot to angle the bottom of the foot toward the midline , while eversion turns the bottom of the foot away from the midline .", "question": { "cloze_format": "The motion that moves the bottom of the foot away from the midline of the body is ___.", "normal_format": "Which motion moves the bottom of the foot away from the midline of the body?", "question_choices": [ "elevation", "dorsiflexion", "eversion", "plantar flexion" ], "question_id": "fs-id2020365", "question_text": "Which motion moves the bottom of the foot away from the midline of the body?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 3, "ans_text": "circumduction" }, "bloom": "1", "hl_context": "<hl> Circumduction is the movement of a body region in a circular manner , in which one end of the body region being moved stays relatively stationary while the other end describes a circle . <hl> It involves the sequential combination of flexion , adduction , extension , and abduction at a joint . This type of motion is found at biaxial condyloid and saddle joints , and at multiaxial ball-and-sockets joints ( see Figure 9.12 e ) .", "hl_sentences": "Circumduction is the movement of a body region in a circular manner , in which one end of the body region being moved stays relatively stationary while the other end describes a circle .", "question": { "cloze_format": "Movement of a body region in a circular movement at a condyloid joint is called the motion of ___ .", "normal_format": "Movement of a body region in a circular movement at a condyloid joint is what type of motion?", "question_choices": [ "rotation", "elevation", "abduction", "circumduction" ], "question_id": "fs-id2058403", "question_text": "Movement of a body region in a circular movement at a condyloid joint is what type of motion?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 0, "ans_text": "hand from the palm backward position to the palm forward position" }, "bloom": "1", "hl_context": "Supination and pronation are the movements of the forearm that go between these two positions . <hl> Pronation is the motion that moves the forearm from the supinated ( anatomical ) position to the pronated ( palm backward ) position . <hl> This motion is produced by rotation of the radius at the proximal radioulnar joint , accompanied by movement of the radius at the distal radioulnar joint . The proximal radioulnar joint is a pivot joint that allows for rotation of the head of the radius . Because of the slight curvature of the shaft of the radius , this rotation causes the distal end of the radius to cross over the distal ulna at the distal radioulnar joint . This crossing over brings the radius and ulna into an X-shape position . <hl> Supination is the opposite motion , in which rotation of the radius returns the bones to their parallel positions and moves the palm to the anterior facing ( supinated ) position . <hl> <hl> It helps to remember that supination is the motion you use when scooping up soup with a spoon ( see Figure 9.13 g ) . <hl>", "hl_sentences": "Pronation is the motion that moves the forearm from the supinated ( anatomical ) position to the pronated ( palm backward ) position . Supination is the opposite motion , in which rotation of the radius returns the bones to their parallel positions and moves the palm to the anterior facing ( supinated ) position . It helps to remember that supination is the motion you use when scooping up soup with a spoon ( see Figure 9.13 g ) .", "question": { "cloze_format": "Supination is the motion that moves the ________.", "normal_format": "Supination is the motion that moves which of the following?", "question_choices": [ "hand from the palm backward position to the palm forward position", "foot so that the bottom of the foot faces the midline of the body", "hand from the palm forward position to the palm backward position", "scapula in an upward direction" ], "question_id": "fs-id1269346", "question_text": "Supination is the motion that moves the ________." }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 2, "ans_text": "abduction" }, "bloom": "1", "hl_context": "Abduction and adduction motions occur within the coronal plane and involve medial-lateral motions of the limbs , fingers , toes , or thumb . <hl> Abduction moves the limb laterally away from the midline of the body , while adduction is the opposing movement that brings the limb toward the body or across the midline . <hl> For example , abduction is raising the arm at the shoulder joint , moving it laterally away from the body , while adduction brings the arm down to the side of the body . Similarly , abduction and adduction at the wrist moves the hand away from or toward the midline of the body . Spreading the fingers or toes apart is also abduction , while bringing the fingers or toes together is adduction . For the thumb , abduction is the anterior movement that brings the thumb to a 90 ° perpendicular position , pointing straight out from the palm . Adduction moves the thumb back to the anatomical position , next to the index finger . Abduction and adduction movements are seen at condyloid , saddle , and ball-and-socket joints ( see Figure 9.12 e ) .", "hl_sentences": "Abduction moves the limb laterally away from the midline of the body , while adduction is the opposing movement that brings the limb toward the body or across the midline .", "question": { "cloze_format": "Movement at the shoulder joint that moves the upper limb laterally away from the body is called ________.", "normal_format": "What is the movement at the shoulder joint that moves the upper limb laterally away from the body?", "question_choices": [ "elevation", "eversion", "abduction", "lateral rotation" ], "question_id": "fs-id1909302", "question_text": "Movement at the shoulder joint that moves the upper limb laterally away from the body is called ________." }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 2, "ans_text": "rotator cuff muscles" }, "bloom": "1", "hl_context": "<hl> However , the primary support for the shoulder joint is provided by muscles crossing the joint , particularly the four rotator cuff muscles . <hl> These muscles ( supraspinatus , infraspinatus , teres minor , and subscapularis ) arise from the scapula and attach to the greater or lesser tubercles of the humerus . As these muscles cross the shoulder joint , their tendons encircle the head of the humerus and become fused to the anterior , superior , and posterior walls of the articular capsule . The thickening of the capsule formed by the fusion of these four muscle tendons is called the rotator cuff . Two bursae , the subacromial bursa and the subscapular bursa , help to prevent friction between the rotator cuff muscle tendons and the scapula as these tendons cross the glenohumeral joint . In addition to their individual actions of moving the upper limb , the rotator cuff muscles also serve to hold the head of the humerus in position within the glenoid cavity . By constantly adjusting their strength of contraction to resist forces acting on the shoulder , these muscles serve as “ dynamic ligaments ” and thus provide the primary structural support for the glenohumeral joint . <hl> The shoulder joint is called the glenohumeral joint . <hl> This is a ball-and-socket joint formed by the articulation between the head of the humerus and the glenoid cavity of the scapula ( Figure 9.16 ) . This joint has the largest range of motion of any joint in the body . However , this freedom of movement is due to the lack of structural support and thus the enhanced mobility is offset by a loss of stability .", "hl_sentences": "However , the primary support for the shoulder joint is provided by muscles crossing the joint , particularly the four rotator cuff muscles . The shoulder joint is called the glenohumeral joint .", "question": { "cloze_format": "The primary support for the glenohumeral joint is provided by the ________.", "normal_format": "Which provides the primary support for the glenohumeral joint?", "question_choices": [ "coracohumeral ligament", "glenoid labrum", "rotator cuff muscles", "subacromial bursa" ], "question_id": "fs-id1548317", "question_text": "The primary support for the glenohumeral joint is provided by the ________." }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 0, "ans_text": "is supported by the annular ligament" }, "bloom": "2", "hl_context": "The articular capsule of the elbow is thin on its anterior and posterior aspects , but is thickened along its outside margins by strong intrinsic ligaments . These ligaments prevent side-to-side movements and hyperextension . On the medial side is the triangular ulnar collateral ligament . This arises from the medial epicondyle of the humerus and attaches to the medial side of the proximal ulna . The strongest part of this ligament is the anterior portion , which resists hyperextension of the elbow . The ulnar collateral ligament may be injured by frequent , forceful extensions of the forearm , as is seen in baseball pitchers . Reconstructive surgical repair of this ligament is referred to as Tommy John surgery , named for the former major league pitcher who was the first person to have this treatment . The lateral side of the elbow is supported by the radial collateral ligament . This arises from the lateral epicondyle of the humerus and then blends into the lateral side of the annular ligament . <hl> The annular ligament encircles the head of the radius . <hl> <hl> This ligament supports the head of the radius as it articulates with the radial notch of the ulna at the proximal radioulnar joint . <hl> This is a pivot joint that allows for rotation of the radius during supination and pronation of the forearm .", "hl_sentences": "The annular ligament encircles the head of the radius . This ligament supports the head of the radius as it articulates with the radial notch of the ulna at the proximal radioulnar joint .", "question": { "cloze_format": "The proximal radioulnar joint ________.", "normal_format": "Which of the following is correct about the proximal radioulnar joint?", "question_choices": [ "is supported by the annular ligament", "contains an articular disc that strongly unites the bones", "is supported by the ulnar collateral ligament", "is a hinge joint that allows for flexion/extension of the forearm" ], "question_id": "fs-id2607694", "question_text": "The proximal radioulnar joint ________." }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 3, "ans_text": "The medial meniscus is attached to the tibial collateral ligament." }, "bloom": "4", "hl_context": "A worse combination of injuries can occur with a hit to the lateral side of the extended knee ( Figure 9.20 ) . <hl> A moderate blow to the lateral knee will cause the medial side of the joint to open , resulting in stretching or damage to the tibial collateral ligament . <hl> <hl> Because the medial meniscus is attached to the tibial collateral ligament , a stronger blow can tear the ligament and also damage the medial meniscus . <hl> This is one reason that the medial meniscus is 20 times more likely to be injured than the lateral meniscus . A powerful blow to the lateral knee produces a “ terrible triad ” injury , in which there is a sequential injury to the tibial collateral ligament , medial meniscus , and anterior cruciate ligament .", "hl_sentences": "A moderate blow to the lateral knee will cause the medial side of the joint to open , resulting in stretching or damage to the tibial collateral ligament . Because the medial meniscus is attached to the tibial collateral ligament , a stronger blow can tear the ligament and also damage the medial meniscus .", "question": { "cloze_format": "The true statement concerning the knee joint is that ___ .", "normal_format": "Which statement is true concerning the knee joint?", "question_choices": [ "The lateral meniscus is an intrinsic ligament located on the lateral side of the knee joint.", "Hyperextension is resisted by the posterior cruciate ligament.", "The anterior cruciate ligament supports the knee when it is flexed and weight bearing.", "The medial meniscus is attached to the tibial collateral ligament." ], "question_id": "fs-id2063165", "question_text": "Which statement is true concerning the knee joint?" }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 2, "ans_text": "is a uniaxial hinge joint" }, "bloom": "1", "hl_context": "Ankle and Foot Joints The ankle is formed by the talocrural joint ( Figure 9.21 ) . It consists of the articulations between the talus bone of the foot and the distal ends of the tibia and fibula of the leg ( crural = “ leg ” ) . The superior aspect of the talus bone is square-shaped and has three areas of articulation . The top of the talus articulates with the inferior tibia . This is the portion of the ankle joint that carries the body weight between the leg and foot . The sides of the talus are firmly held in position by the articulations with the medial malleolus of the tibia and the lateral malleolus of the fibula , which prevent any side-to-side motion of the talus . <hl> The ankle is thus a uniaxial hinge joint that allows only for dorsiflexion and plantar flexion of the foot . <hl>", "hl_sentences": "The ankle is thus a uniaxial hinge joint that allows only for dorsiflexion and plantar flexion of the foot .", "question": { "cloze_format": "The ankle joint ________.", "normal_format": "Which of the following is correct about the ankle joint?", "question_choices": [ "is also called the subtalar joint", "allows for gliding movements that produce inversion/eversion of the foot", "is a uniaxial hinge joint", "is supported by the tibial collateral ligament on the lateral side" ], "question_id": "fs-id2229016", "question_text": "The ankle joint ________." }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 1, "ans_text": "thoracic" }, "bloom": "1", "hl_context": "In addition to being held together by the intervertebral discs , adjacent vertebrae also articulate with each other at synovial joints formed between the superior and inferior articular processes called zygapophysial joints ( facet joints ) ( see Figure 9.3 ) . These are plane joints that provide for only limited motions between the vertebrae . The orientation of the articular processes at these joints varies in different regions of the vertebral column and serves to determine the types of motions available in each vertebral region . The cervical and lumbar regions have the greatest ranges of motions . In the neck , the articular processes of cervical vertebrae are flattened and generally face upward or downward . This orientation provides the cervical vertebral column with extensive ranges of motion for flexion , extension , lateral flexion , and rotation . In the thoracic region , the downward projecting and overlapping spinous processes , along with the attached thoracic cage , greatly limit flexion , extension , and lateral flexion . <hl> However , the flattened and vertically positioned thoracic articular processes allow for the greatest range of rotation within the vertebral column . <hl> The lumbar region allows for considerable extension , flexion , and lateral flexion , but the orientation of the articular processes largely prohibits rotation .", "hl_sentences": "However , the flattened and vertically positioned thoracic articular processes allow for the greatest range of rotation within the vertebral column .", "question": { "cloze_format": "The region of the vertebral column that has the greatest range of motion for rotation is the ___.", "normal_format": "Which region of the vertebral column has the greatest range of motion for rotation?", "question_choices": [ "cervical", "thoracic", "lumbar", "sacral" ], "question_id": "fs-id2094763", "question_text": "Which region of the vertebral column has the greatest range of motion for rotation?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 1, "ans_text": "produces the bones of the top and sides of the skull" }, "bloom": "1", "hl_context": "Joints form during embryonic development in conjunction with the formation and growth of the associated bones . The embryonic tissue that gives rise to all bones , cartilages , and connective tissues of the body is called mesenchyme . <hl> In the head , mesenchyme will accumulate at those areas that will become the bones that form the top and sides of the skull . <hl> <hl> The mesenchyme in these areas will develop directly into bone through the process of intramembranous ossification , in which mesenchymal cells differentiate into bone-producing cells that then generate bone tissue . <hl> The mesenchyme between the areas of bone production will become the fibrous connective tissue that fills the spaces between the developing bones . Initially , the connective tissue-filled gaps between the bones are wide , and are called fontanelles . After birth , as the skull bones grow and enlarge , the gaps between them decrease in width and the fontanelles are reduced to suture joints in which the bones are united by a narrow layer of fibrous connective tissue .", "hl_sentences": "In the head , mesenchyme will accumulate at those areas that will become the bones that form the top and sides of the skull . The mesenchyme in these areas will develop directly into bone through the process of intramembranous ossification , in which mesenchymal cells differentiate into bone-producing cells that then generate bone tissue .", "question": { "cloze_format": "Intramembranous ossification ________.", "normal_format": "Which of the following is correct about intramembranous ossification?", "question_choices": [ "gives rise to the bones of the limbs", "produces the bones of the top and sides of the skull", "produces the bones of the face and base of the skull", "involves the conversion of a hyaline cartilage model into bone" ], "question_id": "fs-id1380698", "question_text": "Intramembranous ossification ________." }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 2, "ans_text": "develop at an interzone site" }, "bloom": "1", "hl_context": "A similar process of endochondral ossification gives rises to the bones and joints of the limbs . The limbs initially develop as small limb buds that appear on the sides of the embryo around the end of the fourth week of development . Starting during the sixth week , as each limb bud continues to grow and elongate , areas of mesenchyme within the bud begin to differentiate into the hyaline cartilage that will form models for of each of the future bones . <hl> The synovial joints will form between the adjacent cartilage models , in an area called the joint interzone . <hl> Cells at the center of this interzone region undergo cell death to form the joint cavity , while surrounding mesenchyme cells will form the articular capsule and supporting ligaments . The process of endochondral ossification , which converts the cartilage models into bone , begins by the twelfth week of embryonic development . At birth , ossification of much of the bone has occurred , but the hyaline cartilage of the epiphyseal plate will remain throughout childhood and adolescence to allow for bone lengthening . Hyaline cartilage is also retained as the articular cartilage that covers the surfaces of the bones at synovial joints .", "hl_sentences": "The synovial joints will form between the adjacent cartilage models , in an area called the joint interzone .", "question": { "cloze_format": "Synovial joints ________.", "normal_format": "What is a characteristic of Synovial joints?", "question_choices": [ "are derived from fontanelles", "are produced by intramembranous ossification", "develop at an interzone site", "are produced by endochondral ossification" ], "question_id": "fs-id1645676", "question_text": "Synovial joints ________." }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 0, "ans_text": "the process that replaces hyaline cartilage with bone tissue" }, "bloom": "1", "hl_context": "<hl> The bones that form the base and facial regions of the skull develop through the process of endochondral ossification . <hl> <hl> In this process , mesenchyme accumulates and differentiates into hyaline cartilage , which forms a model of the future bone . <hl> The hyaline cartilage model is then gradually , over a period of many years , displaced by bone . The mesenchyme between these developing bones becomes the fibrous connective tissue of the suture joints between the bones in these regions of the skull .", "hl_sentences": "The bones that form the base and facial regions of the skull develop through the process of endochondral ossification . In this process , mesenchyme accumulates and differentiates into hyaline cartilage , which forms a model of the future bone .", "question": { "cloze_format": "Endochondral ossification is ________.", "normal_format": "What is endochondral ossification?", "question_choices": [ "the process that replaces hyaline cartilage with bone tissue", "the process by which mesenchyme differentiates directly into bone tissue", "completed before birth", "the process that gives rise to the joint interzone and future joint cavity" ], "question_id": "fs-id2130927", "question_text": "Endochondral ossification is ________." }, "references_are_paraphrase": null } ]
9
9.1 Classification of Joints Learning Objectives By the end of this section, you will be able to: Distinguish between the functional and structural classifications for joints Describe the three functional types of joints and give an example of each List the three types of diarthrodial joints A joint , also called an articulation , is any place where adjacent bones or bone and cartilage come together (articulate with each other) to form a connection. Joints are classified both structurally and functionally. Structural classifications of joints take into account whether the adjacent bones are strongly anchored to each other by fibrous connective tissue or cartilage, or whether the adjacent bones articulate with each other within a fluid-filled space called a joint cavity . Functional classifications describe the degree of movement available between the bones, ranging from immobile, to slightly mobile, to freely moveable joints. The amount of movement available at a particular joint of the body is related to the functional requirements for that joint. Thus immobile or slightly moveable joints serve to protect internal organs, give stability to the body, and allow for limited body movement. In contrast, freely moveable joints allow for much more extensive movements of the body and limbs. Structural Classification of Joints The structural classification of joints is based on whether the articulating surfaces of the adjacent bones are directly connected by fibrous connective tissue or cartilage, or whether the articulating surfaces contact each other within a fluid-filled joint cavity. These differences serve to divide the joints of the body into three structural classifications. A fibrous joint is where the adjacent bones are united by fibrous connective tissue. At a cartilaginous joint , the bones are joined by hyaline cartilage or fibrocartilage. At a synovial joint , the articulating surfaces of the bones are not directly connected, but instead come into contact with each other within a joint cavity that is filled with a lubricating fluid. Synovial joints allow for free movement between the bones and are the most common joints of the body. Functional Classification of Joints The functional classification of joints is determined by the amount of mobility found between the adjacent bones. Joints are thus functionally classified as a synarthrosis or immobile joint, an amphiarthrosis or slightly moveable joint, or as a diarthrosis, which is a freely moveable joint (arthroun = “to fasten by a joint”). Depending on their location, fibrous joints may be functionally classified as a synarthrosis (immobile joint) or an amphiarthrosis (slightly mobile joint). Cartilaginous joints are also functionally classified as either a synarthrosis or an amphiarthrosis joint. All synovial joints are functionally classified as a diarthrosis joint. Synarthrosis An immobile or nearly immobile joint is called a synarthrosis . The immobile nature of these joints provide for a strong union between the articulating bones. This is important at locations where the bones provide protection for internal organs. Examples include sutures, the fibrous joints between the bones of the skull that surround and protect the brain ( Figure 9.2 ), and the manubriosternal joint, the cartilaginous joint that unites the manubrium and body of the sternum for protection of the heart. Amphiarthrosis An amphiarthrosis is a joint that has limited mobility. An example of this type of joint is the cartilaginous joint that unites the bodies of adjacent vertebrae. Filling the gap between the vertebrae is a thick pad of fibrocartilage called an intervertebral disc ( Figure 9.3 ). Each intervertebral disc strongly unites the vertebrae but still allows for a limited amount of movement between them. However, the small movements available between adjacent vertebrae can sum together along the length of the vertebral column to provide for large ranges of body movements. Another example of an amphiarthrosis is the pubic symphysis of the pelvis. This is a cartilaginous joint in which the pubic regions of the right and left hip bones are strongly anchored to each other by fibrocartilage. This joint normally has very little mobility. The strength of the pubic symphysis is important in conferring weight-bearing stability to the pelvis. Diarthrosis A freely mobile joint is classified as a diarthrosis . These types of joints include all synovial joints of the body, which provide the majority of body movements. Most diarthrotic joints are found in the appendicular skeleton and thus give the limbs a wide range of motion. These joints are divided into three categories, based on the number of axes of motion provided by each. An axis in anatomy is described as the movements in reference to the three anatomical planes: transverse, frontal, and sagittal. Thus, diarthroses are classified as uniaxial (for movement in one plane), biaxial (for movement in two planes), or multiaxial joints (for movement in all three anatomical planes). A uniaxial joint only allows for a motion in a single plane (around a single axis). The elbow joint, which only allows for bending or straightening, is an example of a uniaxial joint. A biaxial joint allows for motions within two planes. An example of a biaxial joint is a metacarpophalangeal joint (knuckle joint) of the hand. The joint allows for movement along one axis to produce bending or straightening of the finger, and movement along a second axis, which allows for spreading of the fingers away from each other and bringing them together. A joint that allows for the several directions of movement is called a multiaxial joint (polyaxial or triaxial joint). This type of diarthrotic joint allows for movement along three axes ( Figure 9.4 ). The shoulder and hip joints are multiaxial joints. They allow the upper or lower limb to move in an anterior-posterior direction and a medial-lateral direction. In addition, the limb can also be rotated around its long axis. This third movement results in rotation of the limb so that its anterior surface is moved either toward or away from the midline of the body. 9.2 Fibrous Joints Learning Objectives By the end of this section, you will be able to: Describe the structural features of fibrous joints Distinguish between a suture, syndesmosis, and gomphosis Give an example of each type of fibrous joint At a fibrous joint, the adjacent bones are directly connected to each other by fibrous connective tissue, and thus the bones do not have a joint cavity between them ( Figure 9.5 ). The gap between the bones may be narrow or wide. There are three types of fibrous joints. A suture is the narrow fibrous joint found between most bones of the skull. At a syndesmosis joint, the bones are more widely separated but are held together by a narrow band of fibrous connective tissue called a ligament or a wide sheet of connective tissue called an interosseous membrane. This type of fibrous joint is found between the shaft regions of the long bones in the forearm and in the leg. Lastly, a gomphosis is the narrow fibrous joint between the roots of a tooth and the bony socket in the jaw into which the tooth fits. Suture All the bones of the skull, except for the mandible, are joined to each other by a fibrous joint called a suture . The fibrous connective tissue found at a suture (“to bind or sew”) strongly unites the adjacent skull bones and thus helps to protect the brain and form the face. In adults, the skull bones are closely opposed and fibrous connective tissue fills the narrow gap between the bones. The suture is frequently convoluted, forming a tight union that prevents most movement between the bones. (See Figure 9.5 a .) Thus, skull sutures are functionally classified as a synarthrosis, although some sutures may allow for slight movements between the cranial bones. In newborns and infants, the areas of connective tissue between the bones are much wider, especially in those areas on the top and sides of the skull that will become the sagittal, coronal, squamous, and lambdoid sutures. These broad areas of connective tissue are called fontanelles ( Figure 9.6 ). During birth, the fontanelles provide flexibility to the skull, allowing the bones to push closer together or to overlap slightly, thus aiding movement of the infant’s head through the birth canal. After birth, these expanded regions of connective tissue allow for rapid growth of the skull and enlargement of the brain. The fontanelles greatly decrease in width during the first year after birth as the skull bones enlarge. When the connective tissue between the adjacent bones is reduced to a narrow layer, these fibrous joints are now called sutures. At some sutures, the connective tissue will ossify and be converted into bone, causing the adjacent bones to fuse to each other. This fusion between bones is called a synostosis (“joined by bone”). Examples of synostosis fusions between cranial bones are found both early and late in life. At the time of birth, the frontal and maxillary bones consist of right and left halves joined together by sutures, which disappear by the eighth year as the halves fuse together to form a single bone. Late in life, the sagittal, coronal, and lambdoid sutures of the skull will begin to ossify and fuse, causing the suture line to gradually disappear. Syndesmosis A syndesmosis (“fastened with a band”) is a type of fibrous joint in which two parallel bones are united to each other by fibrous connective tissue. The gap between the bones may be narrow, with the bones joined by ligaments, or the gap may be wide and filled in by a broad sheet of connective tissue called an interosseous membrane . In the forearm, the wide gap between the shaft portions of the radius and ulna bones are strongly united by an interosseous membrane (see Figure 9.5 b ). Similarly, in the leg, the shafts of the tibia and fibula are also united by an interosseous membrane. In addition, at the distal tibiofibular joint, the articulating surfaces of the bones lack cartilage and the narrow gap between the bones is anchored by fibrous connective tissue and ligaments on both the anterior and posterior aspects of the joint. Together, the interosseous membrane and these ligaments form the tibiofibular syndesmosis. The syndesmoses found in the forearm and leg serve to unite parallel bones and prevent their separation. However, a syndesmosis does not prevent all movement between the bones, and thus this type of fibrous joint is functionally classified as an amphiarthrosis. In the leg, the syndesmosis between the tibia and fibula strongly unites the bones, allows for little movement, and firmly locks the talus bone in place between the tibia and fibula at the ankle joint. This provides strength and stability to the leg and ankle, which are important during weight bearing. In the forearm, the interosseous membrane is flexible enough to allow for rotation of the radius bone during forearm movements. Thus in contrast to the stability provided by the tibiofibular syndesmosis, the flexibility of the antebrachial interosseous membrane allows for the much greater mobility of the forearm. The interosseous membranes of the leg and forearm also provide areas for muscle attachment. Damage to a syndesmotic joint, which usually results from a fracture of the bone with an accompanying tear of the interosseous membrane, will produce pain, loss of stability of the bones, and may damage the muscles attached to the interosseous membrane. If the fracture site is not properly immobilized with a cast or splint, contractile activity by these muscles can cause improper alignment of the broken bones during healing. Gomphosis A gomphosis (“fastened with bolts”) is the specialized fibrous joint that anchors the root of a tooth into its bony socket within the maxillary bone (upper jaw) or mandible bone (lower jaw) of the skull. A gomphosis is also known as a peg-and-socket joint. Spanning between the bony walls of the socket and the root of the tooth are numerous short bands of dense connective tissue, each of which is called a periodontal ligament (see Figure 9.5 c ). Due to the immobility of a gomphosis, this type of joint is functionally classified as a synarthrosis. 9.3 Cartilaginous Joints Learning Objectives By the end of this section, you will be able to: Describe the structural features of cartilaginous joints Distinguish between a synchondrosis and symphysis Give an example of each type of cartilaginous joint As the name indicates, at a cartilaginous joint, the adjacent bones are united by cartilage, a tough but flexible type of connective tissue. These types of joints lack a joint cavity and involve bones that are joined together by either hyaline cartilage or fibrocartilage ( Figure 9.7 ). There are two types of cartilaginous joints. A synchondrosis is a cartilaginous joint where the bones are joined by hyaline cartilage. Also classified as a synchondrosis are places where bone is united to a cartilage structure, such as between the anterior end of a rib and the costal cartilage of the thoracic cage. The second type of cartilaginous joint is a symphysis, where the bones are joined by fibrocartilage. Synchondrosis A synchondrosis (“joined by cartilage”) is a cartilaginous joint where bones are joined together by hyaline cartilage, or where bone is united to hyaline cartilage. A synchondrosis may be temporary or permanent. A temporary synchondrosis is the epiphyseal plate (growth plate) of a growing long bone. The epiphyseal plate is the region of growing hyaline cartilage that unites the diaphysis (shaft) of the bone to the epiphysis (end of the bone). Bone lengthening involves growth of the epiphyseal plate cartilage and its replacement by bone, which adds to the diaphysis. For many years during childhood growth, the rates of cartilage growth and bone formation are equal and thus the epiphyseal plate does not change in overall thickness as the bone lengthens. During the late teens and early 20s, growth of the cartilage slows and eventually stops. The epiphyseal plate is then completely replaced by bone, and the diaphysis and epiphysis portions of the bone fuse together to form a single adult bone. This fusion of the diaphysis and epiphysis is a synostosis. Once this occurs, bone lengthening ceases. For this reason, the epiphyseal plate is considered to be a temporary synchondrosis. Because cartilage is softer than bone tissue, injury to a growing long bone can damage the epiphyseal plate cartilage, thus stopping bone growth and preventing additional bone lengthening. Growing layers of cartilage also form synchondroses that join together the ilium, ischium, and pubic portions of the hip bone during childhood and adolescence. When body growth stops, the cartilage disappears and is replaced by bone, forming synostoses and fusing the bony components together into the single hip bone of the adult. Similarly, synostoses unite the sacral vertebrae that fuse together to form the adult sacrum. Interactive Link Visit this website to view a radiograph (X-ray image) of a child’s hand and wrist. The growing bones of child have an epiphyseal plate that forms a synchondrosis between the shaft and end of a long bone. Being less dense than bone, the area of epiphyseal cartilage is seen on this radiograph as the dark epiphyseal gaps located near the ends of the long bones, including the radius, ulna, metacarpal, and phalanx bones. Which of the bones in this image do not show an epiphyseal plate (epiphyseal gap)? Examples of permanent synchondroses are found in the thoracic cage. One example is the first sternocostal joint, where the first rib is anchored to the manubrium by its costal cartilage. (The articulations of the remaining costal cartilages to the sternum are all synovial joints.) Additional synchondroses are formed where the anterior end of the other 11 ribs is joined to its costal cartilage. Unlike the temporary synchondroses of the epiphyseal plate, these permanent synchondroses retain their hyaline cartilage and thus do not ossify with age. Due to the lack of movement between the bone and cartilage, both temporary and permanent synchondroses are functionally classified as a synarthrosis. Symphysis A cartilaginous joint where the bones are joined by fibrocartilage is called a symphysis (“growing together”). Fibrocartilage is very strong because it contains numerous bundles of thick collagen fibers, thus giving it a much greater ability to resist pulling and bending forces when compared with hyaline cartilage. This gives symphyses the ability to strongly unite the adjacent bones, but can still allow for limited movement to occur. Thus, a symphysis is functionally classified as an amphiarthrosis. The gap separating the bones at a symphysis may be narrow or wide. Examples in which the gap between the bones is narrow include the pubic symphysis and the manubriosternal joint. At the pubic symphysis, the pubic portions of the right and left hip bones of the pelvis are joined together by fibrocartilage across a narrow gap. Similarly, at the manubriosternal joint, fibrocartilage unites the manubrium and body portions of the sternum. The intervertebral symphysis is a wide symphysis located between the bodies of adjacent vertebrae of the vertebral column. Here a thick pad of fibrocartilage called an intervertebral disc strongly unites the adjacent vertebrae by filling the gap between them. The width of the intervertebral symphysis is important because it allows for small movements between the adjacent vertebrae. In addition, the thick intervertebral disc provides cushioning between the vertebrae, which is important when carrying heavy objects or during high-impact activities such as running or jumping. 9.4 Synovial Joints Learning Objectives By the end of this section, you will be able to: Describe the structural features of a synovial joint Discuss the function of additional structures associated with synovial joints List the six types of synovial joints and give an example of each Synovial joints are the most common type of joint in the body ( Figure 9.8 ). A key structural characteristic for a synovial joint that is not seen at fibrous or cartilaginous joints is the presence of a joint cavity. This fluid-filled space is the site at which the articulating surfaces of the bones contact each other. Also unlike fibrous or cartilaginous joints, the articulating bone surfaces at a synovial joint are not directly connected to each other with fibrous connective tissue or cartilage. This gives the bones of a synovial joint the ability to move smoothly against each other, allowing for increased joint mobility. Structural Features of Synovial Joints Synovial joints are characterized by the presence of a joint cavity. The walls of this space are formed by the articular capsule , a fibrous connective tissue structure that is attached to each bone just outside the area of the bone’s articulating surface. The bones of the joint articulate with each other within the joint cavity. Friction between the bones at a synovial joint is prevented by the presence of the articular cartilage , a thin layer of hyaline cartilage that covers the entire articulating surface of each bone. However, unlike at a cartilaginous joint, the articular cartilages of each bone are not continuous with each other. Instead, the articular cartilage acts like a Teflon ® coating over the bone surface, allowing the articulating bones to move smoothly against each other without damaging the underlying bone tissue. Lining the inner surface of the articular capsule is a thin synovial membrane . The cells of this membrane secrete synovial fluid (synovia = “a thick fluid”), a thick, slimy fluid that provides lubrication to further reduce friction between the bones of the joint. This fluid also provides nourishment to the articular cartilage, which does not contain blood vessels. The ability of the bones to move smoothly against each other within the joint cavity, and the freedom of joint movement this provides, means that each synovial joint is functionally classified as a diarthrosis. Outside of their articulating surfaces, the bones are connected together by ligaments, which are strong bands of fibrous connective tissue. These strengthen and support the joint by anchoring the bones together and preventing their separation. Ligaments allow for normal movements at a joint, but limit the range of these motions, thus preventing excessive or abnormal joint movements. Ligaments are classified based on their relationship to the fibrous articular capsule. An extrinsic ligament is located outside of the articular capsule, an intrinsic ligament is fused to or incorporated into the wall of the articular capsule, and an intracapsular ligament is located inside of the articular capsule. At many synovial joints, additional support is provided by the muscles and their tendons that act across the joint. A tendon is the dense connective tissue structure that attaches a muscle to bone. As forces acting on a joint increase, the body will automatically increase the overall strength of contraction of the muscles crossing that joint, thus allowing the muscle and its tendon to serve as a “dynamic ligament” to resist forces and support the joint. This type of indirect support by muscles is very important at the shoulder joint, for example, where the ligaments are relatively weak. Additional Structures Associated with Synovial Joints A few synovial joints of the body have a fibrocartilage structure located between the articulating bones. This is called an articular disc , which is generally small and oval-shaped, or a meniscus , which is larger and C-shaped. These structures can serve several functions, depending on the specific joint. In some places, an articular disc may act to strongly unite the bones of the joint to each other. Examples of this include the articular discs found at the sternoclavicular joint or between the distal ends of the radius and ulna bones. At other synovial joints, the disc can provide shock absorption and cushioning between the bones, which is the function of each meniscus within the knee joint. Finally, an articular disc can serve to smooth the movements between the articulating bones, as seen at the temporomandibular joint. Some synovial joints also have a fat pad, which can serve as a cushion between the bones. Additional structures located outside of a synovial joint serve to prevent friction between the bones of the joint and the overlying muscle tendons or skin. A bursa (plural = bursae) is a thin connective tissue sac filled with lubricating liquid. They are located in regions where skin, ligaments, muscles, or muscle tendons can rub against each other, usually near a body joint ( Figure 9.9 ). Bursae reduce friction by separating the adjacent structures, preventing them from rubbing directly against each other. Bursae are classified by their location. A subcutaneous bursa is located between the skin and an underlying bone. It allows skin to move smoothly over the bone. Examples include the prepatellar bursa located over the kneecap and the olecranon bursa at the tip of the elbow. A submuscular bursa is found between a muscle and an underlying bone, or between adjacent muscles. These prevent rubbing of the muscle during movements. A large submuscular bursa, the trochanteric bursa, is found at the lateral hip, between the greater trochanter of the femur and the overlying gluteus maximus muscle. A subtendinous bursa is found between a tendon and a bone. Examples include the subacromial bursa that protects the tendon of shoulder muscle as it passes under the acromion of the scapula, and the suprapatellar bursa that separates the tendon of the large anterior thigh muscle from the distal femur just above the knee. A tendon sheath is similar in structure to a bursa, but smaller. It is a connective tissue sac that surrounds a muscle tendon at places where the tendon crosses a joint. It contains a lubricating fluid that allows for smooth motions of the tendon during muscle contraction and joint movements. Homeostatic Imbalances Bursitis Bursitis is the inflammation of a bursa near a joint. This will cause pain, swelling, or tenderness of the bursa and surrounding area, and may also result in joint stiffness. Bursitis is most commonly associated with the bursae found at or near the shoulder, hip, knee, or elbow joints. At the shoulder, subacromial bursitis may occur in the bursa that separates the acromion of the scapula from the tendon of a shoulder muscle as it passes deep to the acromion. In the hip region, trochanteric bursitis can occur in the bursa that overlies the greater trochanter of the femur, just below the lateral side of the hip. Ischial bursitis occurs in the bursa that separates the skin from the ischial tuberosity of the pelvis, the bony structure that is weight bearing when sitting. At the knee, inflammation and swelling of the bursa located between the skin and patella bone is prepatellar bursitis (“housemaid’s knee”), a condition more commonly seen today in roofers or floor and carpet installers who do not use knee pads. At the elbow, olecranon bursitis is inflammation of the bursa between the skin and olecranon process of the ulna. The olecranon forms the bony tip of the elbow, and bursitis here is also known as “student’s elbow.” Bursitis can be either acute (lasting only a few days) or chronic. It can arise from muscle overuse, trauma, excessive or prolonged pressure on the skin, rheumatoid arthritis, gout, or infection of the joint. Repeated acute episodes of bursitis can result in a chronic condition. Treatments for the disorder include antibiotics if the bursitis is caused by an infection, or anti-inflammatory agents, such as nonsteroidal anti-inflammatory drugs (NSAIDs) or corticosteroids if the bursitis is due to trauma or overuse. Chronic bursitis may require that fluid be drained, but additional surgery is usually not required. Types of Synovial Joints Synovial joints are subdivided based on the shapes of the articulating surfaces of the bones that form each joint. The six types of synovial joints are pivot, hinge, condyloid, saddle, plane, and ball-and socket-joints ( Figure 9.10 ). Pivot Joint At a pivot joint , a rounded portion of a bone is enclosed within a ring formed partially by the articulation with another bone and partially by a ligament (see Figure 9.10 a ). The bone rotates within this ring. Since the rotation is around a single axis, pivot joints are functionally classified as a uniaxial diarthrosis type of joint. An example of a pivot joint is the atlantoaxial joint, found between the C1 (atlas) and C2 (axis) vertebrae. Here, the upward projecting dens of the axis articulates with the inner aspect of the atlas, where it is held in place by a ligament. Rotation at this joint allows you to turn your head from side to side. A second pivot joint is found at the proximal radioulnar joint . Here, the head of the radius is largely encircled by a ligament that holds it in place as it articulates with the radial notch of the ulna. Rotation of the radius allows for forearm movements. Hinge Joint In a hinge joint , the convex end of one bone articulates with the concave end of the adjoining bone (see Figure 9.10 b ). This type of joint allows only for bending and straightening motions along a single axis, and thus hinge joints are functionally classified as uniaxial joints. A good example is the elbow joint, with the articulation between the trochlea of the humerus and the trochlear notch of the ulna. Other hinge joints of the body include the knee, ankle, and interphalangeal joints between the phalanx bones of the fingers and toes. Condyloid Joint At a condyloid joint (ellipsoid joint), the shallow depression at the end of one bone articulates with a rounded structure from an adjacent bone or bones (see Figure 9.10 e ). The knuckle (metacarpophalangeal) joints of the hand between the distal end of a metacarpal bone and the proximal phalanx bone are condyloid joints. Another example is the radiocarpal joint of the wrist, between the shallow depression at the distal end of the radius bone and the rounded scaphoid, lunate, and triquetrum carpal bones. In this case, the articulation area has a more oval (elliptical) shape. Functionally, condyloid joints are biaxial joints that allow for two planes of movement. One movement involves the bending and straightening of the fingers or the anterior-posterior movements of the hand. The second movement is a side-to-side movement, which allows you to spread your fingers apart and bring them together, or to move your hand in a medial-going or lateral-going direction. Saddle Joint At a saddle joint , both of the articulating surfaces for the bones have a saddle shape, which is concave in one direction and convex in the other (see Figure 9.10 c ). This allows the two bones to fit together like a rider sitting on a saddle. Saddle joints are functionally classified as biaxial joints. The primary example is the first carpometacarpal joint, between the trapezium (a carpal bone) and the first metacarpal bone at the base of the thumb. This joint provides the thumb the ability to move away from the palm of the hand along two planes. Thus, the thumb can move within the same plane as the palm of the hand, or it can jut out anteriorly, perpendicular to the palm. This movement of the first carpometacarpal joint is what gives humans their distinctive “opposable” thumbs. The sternoclavicular joint is also classified as a saddle joint. Plane Joint At a plane joint (gliding joint), the articulating surfaces of the bones are flat or slightly curved and of approximately the same size, which allows the bones to slide against each other (see Figure 9.10 d ). The motion at this type of joint is usually small and tightly constrained by surrounding ligaments. Based only on their shape, plane joints can allow multiple movements, including rotation. Thus plane joints can be functionally classified as a multiaxial joint. However, not all of these movements are available to every plane joint due to limitations placed on it by ligaments or neighboring bones. Thus, depending upon the specific joint of the body, a plane joint may exhibit only a single type of movement or several movements. Plane joints are found between the carpal bones (intercarpal joints) of the wrist or tarsal bones (intertarsal joints) of the foot, between the clavicle and acromion of the scapula (acromioclavicular joint), and between the superior and inferior articular processes of adjacent vertebrae (zygapophysial joints). Ball-and-Socket Joint The joint with the greatest range of motion is the ball-and-socket joint . At these joints, the rounded head of one bone (the ball) fits into the concave articulation (the socket) of the adjacent bone (see Figure 9.10 f ). The hip joint and the glenohumeral (shoulder) joint are the only ball-and-socket joints of the body. At the hip joint, the head of the femur articulates with the acetabulum of the hip bone, and at the shoulder joint, the head of the humerus articulates with the glenoid cavity of the scapula. Ball-and-socket joints are classified functionally as multiaxial joints. The femur and the humerus are able to move in both anterior-posterior and medial-lateral directions and they can also rotate around their long axis. The shallow socket formed by the glenoid cavity allows the shoulder joint an extensive range of motion. In contrast, the deep socket of the acetabulum and the strong supporting ligaments of the hip joint serve to constrain movements of the femur, reflecting the need for stability and weight-bearing ability at the hip. Interactive Link Watch this video to see an animation of synovial joints in action. Synovial joints are places where bones articulate with each other inside of a joint cavity. The different types of synovial joints are the ball-and-socket joint (shoulder joint), hinge joint (knee), pivot joint (atlantoaxial joint, between C1 and C2 vertebrae of the neck), condyloid joint (radiocarpal joint of the wrist), saddle joint (first carpometacarpal joint, between the trapezium carpal bone and the first metacarpal bone, at the base of the thumb), and plane joint (facet joints of vertebral column, between superior and inferior articular processes). Which type of synovial joint allows for the widest range of motion? Aging and the... Joints Arthritis is a common disorder of synovial joints that involves inflammation of the joint. This often results in significant joint pain, along with swelling, stiffness, and reduced joint mobility. There are more than 100 different forms of arthritis. Arthritis may arise from aging, damage to the articular cartilage, autoimmune diseases, bacterial or viral infections, or unknown (probably genetic) causes. The most common type of arthritis is osteoarthritis, which is associated with aging and “wear and tear” of the articular cartilage ( Figure 9.11 ). Risk factors that may lead to osteoarthritis later in life include injury to a joint; jobs that involve physical labor; sports with running, twisting, or throwing actions; and being overweight. These factors put stress on the articular cartilage that covers the surfaces of bones at synovial joints, causing the cartilage to gradually become thinner. As the articular cartilage layer wears down, more pressure is placed on the bones. The joint responds by increasing production of the lubricating synovial fluid, but this can lead to swelling of the joint cavity, causing pain and joint stiffness as the articular capsule is stretched. The bone tissue underlying the damaged articular cartilage also responds by thickening, producing irregularities and causing the articulating surface of the bone to become rough or bumpy. Joint movement then results in pain and inflammation. In its early stages, symptoms of osteoarthritis may be reduced by mild activity that “warms up” the joint, but the symptoms may worsen following exercise. In individuals with more advanced osteoarthritis, the affected joints can become more painful and therefore are difficult to use effectively, resulting in increased immobility. There is no cure for osteoarthritis, but several treatments can help alleviate the pain. Treatments may include lifestyle changes, such as weight loss and low-impact exercise, and over-the-counter or prescription medications that help to alleviate the pain and inflammation. For severe cases, joint replacement surgery (arthroplasty) may be required. Joint replacement is a very invasive procedure, so other treatments are always tried before surgery. However arthroplasty can provide relief from chronic pain and can enhance mobility within a few months following the surgery. This type of surgery involves replacing the articular surfaces of the bones with prosthesis (artificial components). For example, in hip arthroplasty, the worn or damaged parts of the hip joint, including the head and neck of the femur and the acetabulum of the pelvis, are removed and replaced with artificial joint components. The replacement head for the femur consists of a rounded ball attached to the end of a shaft that is inserted inside the diaphysis of the femur. The acetabulum of the pelvis is reshaped and a replacement socket is fitted into its place. The parts, which are always built in advance of the surgery, are sometimes custom made to produce the best possible fit for a patient. Gout is a form of arthritis that results from the deposition of uric acid crystals within a body joint. Usually only one or a few joints are affected, such as the big toe, knee, or ankle. The attack may only last a few days, but may return to the same or another joint. Gout occurs when the body makes too much uric acid or the kidneys do not properly excrete it. A diet with excessive fructose has been implicated in raising the chances of a susceptible individual developing gout. Other forms of arthritis are associated with various autoimmune diseases, bacterial infections of the joint, or unknown genetic causes. Autoimmune diseases, including rheumatoid arthritis, scleroderma, or systemic lupus erythematosus, produce arthritis because the immune system of the body attacks the body joints. In rheumatoid arthritis, the joint capsule and synovial membrane become inflamed. As the disease progresses, the articular cartilage is severely damaged or destroyed, resulting in joint deformation, loss of movement, and severe disability. The most commonly involved joints are the hands, feet, and cervical spine, with corresponding joints on both sides of the body usually affected, though not always to the same extent. Rheumatoid arthritis is also associated with lung fibrosis, vasculitis (inflammation of blood vessels), coronary heart disease, and premature mortality. With no known cure, treatments are aimed at alleviating symptoms. Exercise, anti-inflammatory and pain medications, various specific disease-modifying anti-rheumatic drugs, or surgery are used to treat rheumatoid arthritis. Interactive Link Visit this website to learn about a patient who arrives at the hospital with joint pain and weakness in his legs. What caused this patient’s weakness? Interactive Link Watch this animation to observe hip replacement surgery (total hip arthroplasty), which can be used to alleviate the pain and loss of joint mobility associated with osteoarthritis of the hip joint. What is the most common cause of hip disability? Interactive Link Watch this video to learn about the symptoms and treatments for rheumatoid arthritis. Which system of the body malfunctions in rheumatoid arthritis and what does this cause? 9.5 Types of Body Movements Learning Objectives By the end of this section, you will be able to: Define the different types of body movements Identify the joints that allow for these motions Synovial joints allow the body a tremendous range of movements. Each movement at a synovial joint results from the contraction or relaxation of the muscles that are attached to the bones on either side of the articulation. The type of movement that can be produced at a synovial joint is determined by its structural type. While the ball-and-socket joint gives the greatest range of movement at an individual joint, in other regions of the body, several joints may work together to produce a particular movement. Overall, each type of synovial joint is necessary to provide the body with its great flexibility and mobility. There are many types of movement that can occur at synovial joints ( Table 9.1 ). Movement types are generally paired, with one being the opposite of the other. Body movements are always described in relation to the anatomical position of the body: upright stance, with upper limbs to the side of body and palms facing forward. Refer to Figure 9.12 as you go through this section. Interactive Link Watch this video to learn about anatomical motions. What motions involve increasing or decreasing the angle of the foot at the ankle? Flexion and Extension Flexion and extension are typically movements that take place within the sagittal plane and involve anterior or posterior movements of the neck, trunk, or limbs. For the vertebral column, flexion (anterior flexion) is an anterior (forward) bending of the neck or trunk, while extension involves a posterior-directed motion, such as straightening from a flexed position or bending backward. Lateral flexion of the vertebral column occurs in the coronal plane and is defined as the bending of the neck or trunk toward the right or left side.. These movements of the vertebral column involve both the symphysis joint formed by each intervertebral disc, as well as the plane type of synovial joint formed between the inferior articular processes of one vertebra and the superior articular processes of the next lower vertebra. In the limbs, flexion decreases the angle between the bones (bending of the joint), while extension increases the angle and straightens the joint. For the upper limb, all anterior-going motions are flexion and all posterior-going motions are extension. These include anterior-posterior movements of the arm at the shoulder, the forearm at the elbow, the hand at the wrist, and the fingers at the metacarpophalangeal and interphalangeal joints. For the thumb, extension moves the thumb away from the palm of the hand, within the same plane as the palm, while flexion brings the thumb back against the index finger or into the palm. These motions take place at the first carpometacarpal joint. In the lower limb, bringing the thigh forward and upward is flexion at the hip joint, while any posterior-going motion of the thigh is extension. Note that extension of the thigh beyond the anatomical (standing) position is greatly limited by the ligaments that support the hip joint. Knee flexion is the bending of the knee to bring the foot toward the posterior thigh, and extension is the straightening of the knee. Flexion and extension movements are seen at the hinge, condyloid, saddle, and ball-and-socket joints of the limbs (see Figure 9.12 a-d ). Hyperextension is the abnormal or excessive extension of a joint beyond its normal range of motion, thus resulting in injury. Similarly, hyperflexion is excessive flexion at a joint. Hyperextension injuries are common at hinge joints such as the knee or elbow. In cases of “whiplash” in which the head is suddenly moved backward and then forward, a patient may experience both hyperextension and hyperflexion of the cervical region. Abduction and Adduction Abduction and adduction motions occur within the coronal plane and involve medial-lateral motions of the limbs, fingers, toes, or thumb. Abduction moves the limb laterally away from the midline of the body, while adduction is the opposing movement that brings the limb toward the body or across the midline. For example, abduction is raising the arm at the shoulder joint, moving it laterally away from the body, while adduction brings the arm down to the side of the body. Similarly, abduction and adduction at the wrist moves the hand away from or toward the midline of the body. Spreading the fingers or toes apart is also abduction, while bringing the fingers or toes together is adduction. For the thumb, abduction is the anterior movement that brings the thumb to a 90° perpendicular position, pointing straight out from the palm. Adduction moves the thumb back to the anatomical position, next to the index finger. Abduction and adduction movements are seen at condyloid, saddle, and ball-and-socket joints (see Figure 9.12 e ). Circumduction Circumduction is the movement of a body region in a circular manner, in which one end of the body region being moved stays relatively stationary while the other end describes a circle. It involves the sequential combination of flexion, adduction, extension, and abduction at a joint. This type of motion is found at biaxial condyloid and saddle joints, and at multiaxial ball-and-sockets joints (see Figure 9.12 e ). Rotation Rotation can occur within the vertebral column, at a pivot joint, or at a ball-and-socket joint. Rotation of the neck or body is the twisting movement produced by the summation of the small rotational movements available between adjacent vertebrae. At a pivot joint, one bone rotates in relation to another bone. This is a uniaxial joint, and thus rotation is the only motion allowed at a pivot joint. For example, at the atlantoaxial joint, the first cervical (C1) vertebra (atlas) rotates around the dens, the upward projection from the second cervical (C2) vertebra (axis). This allows the head to rotate from side to side as when shaking the head “no.” The proximal radioulnar joint is a pivot joint formed by the head of the radius and its articulation with the ulna. This joint allows for the radius to rotate along its length during pronation and supination movements of the forearm. Rotation can also occur at the ball-and-socket joints of the shoulder and hip. Here, the humerus and femur rotate around their long axis, which moves the anterior surface of the arm or thigh either toward or away from the midline of the body. Movement that brings the anterior surface of the limb toward the midline of the body is called medial (internal) rotation . Conversely, rotation of the limb so that the anterior surface moves away from the midline is lateral (external) rotation (see Figure 9.12 f ). Be sure to distinguish medial and lateral rotation, which can only occur at the multiaxial shoulder and hip joints, from circumduction, which can occur at either biaxial or multiaxial joints. Supination and Pronation Supination and pronation are movements of the forearm. In the anatomical position, the upper limb is held next to the body with the palm facing forward. This is the supinated position of the forearm. In this position, the radius and ulna are parallel to each other. When the palm of the hand faces backward, the forearm is in the pronated position , and the radius and ulna form an X-shape. Supination and pronation are the movements of the forearm that go between these two positions. Pronation is the motion that moves the forearm from the supinated (anatomical) position to the pronated (palm backward) position. This motion is produced by rotation of the radius at the proximal radioulnar joint, accompanied by movement of the radius at the distal radioulnar joint. The proximal radioulnar joint is a pivot joint that allows for rotation of the head of the radius. Because of the slight curvature of the shaft of the radius, this rotation causes the distal end of the radius to cross over the distal ulna at the distal radioulnar joint. This crossing over brings the radius and ulna into an X-shape position. Supination is the opposite motion, in which rotation of the radius returns the bones to their parallel positions and moves the palm to the anterior facing (supinated) position. It helps to remember that supination is the motion you use when scooping up soup with a spoon (see Figure 9.13 g ). Dorsiflexion and Plantar Flexion Dorsiflexion and plantar flexion are movements at the ankle joint, which is a hinge joint. Lifting the front of the foot, so that the top of the foot moves toward the anterior leg is dorsiflexion, while lifting the heel of the foot from the ground or pointing the toes downward is plantar flexion. These are the only movements available at the ankle joint (see Figure 9.13 h ). Inversion and Eversion Inversion and eversion are complex movements that involve the multiple plane joints among the tarsal bones of the posterior foot (intertarsal joints) and thus are not motions that take place at the ankle joint. Inversion is the turning of the foot to angle the bottom of the foot toward the midline, while eversion turns the bottom of the foot away from the midline. The foot has a greater range of inversion than eversion motion. These are important motions that help to stabilize the foot when walking or running on an uneven surface and aid in the quick side-to-side changes in direction used during active sports such as basketball, racquetball, or soccer (see Figure 9.13 i ). Protraction and Retraction Protraction and retraction are anterior-posterior movements of the scapula or mandible. Protraction of the scapula occurs when the shoulder is moved forward, as when pushing against something or throwing a ball. Retraction is the opposite motion, with the scapula being pulled posteriorly and medially, toward the vertebral column. For the mandible, protraction occurs when the lower jaw is pushed forward, to stick out the chin, while retraction pulls the lower jaw backward. (See Figure 9.13 j .) Depression and Elevation Depression and elevation are downward and upward movements of the scapula or mandible. The upward movement of the scapula and shoulder is elevation, while a downward movement is depression. These movements are used to shrug your shoulders. Similarly, elevation of the mandible is the upward movement of the lower jaw used to close the mouth or bite on something, and depression is the downward movement that produces opening of the mouth (see Figure 9.13 k ). Excursion Excursion is the side to side movement of the mandible. Lateral excursion moves the mandible away from the midline, toward either the right or left side. Medial excursion returns the mandible to its resting position at the midline. Superior Rotation and Inferior Rotation Superior and inferior rotation are movements of the scapula and are defined by the direction of movement of the glenoid cavity. These motions involve rotation of the scapula around a point inferior to the scapular spine and are produced by combinations of muscles acting on the scapula. During superior rotation , the glenoid cavity moves upward as the medial end of the scapular spine moves downward. This is a very important motion that contributes to upper limb abduction. Without superior rotation of the scapula, the greater tubercle of the humerus would hit the acromion of the scapula, thus preventing any abduction of the arm above shoulder height. Superior rotation of the scapula is thus required for full abduction of the upper limb. Superior rotation is also used without arm abduction when carrying a heavy load with your hand or on your shoulder. You can feel this rotation when you pick up a load, such as a heavy book bag and carry it on only one shoulder. To increase its weight-bearing support for the bag, the shoulder lifts as the scapula superiorly rotates. Inferior rotation occurs during limb adduction and involves the downward motion of the glenoid cavity with upward movement of the medial end of the scapular spine. Opposition and Reposition Opposition is the thumb movement that brings the tip of the thumb in contact with the tip of a finger. This movement is produced at the first carpometacarpal joint, which is a saddle joint formed between the trapezium carpal bone and the first metacarpal bone. Thumb opposition is produced by a combination of flexion and abduction of the thumb at this joint. Returning the thumb to its anatomical position next to the index finger is called reposition (see Figure 9.13 l ). Movements of the Joints Type of Joint Movement Example Pivot Uniaxial joint; allows rotational movement Atlantoaxial joint (C1–C2 vertebrae articulation); proximal radioulnar joint Hinge Uniaxial joint; allows flexion/extension movements Knee; elbow; ankle; interphalangeal joints of fingers and toes Condyloid Biaxial joint; allows flexion/extension, abduction/adduction, and circumduction movements Metacarpophalangeal (knuckle) joints of fingers; radiocarpal joint of wrist; metatarsophalangeal joints for toes Saddle Biaxial joint; allows flexion/extension, abduction/adduction, and circumduction movements First carpometacarpal joint of the thumb; sternoclavicular joint Plane Multiaxial joint; allows inversion and eversion of foot, or flexion, extension, and lateral flexion of the vertebral column Intertarsal joints of foot; superior-inferior articular process articulations between vertebrae Ball-and-socket Multiaxial joint; allows flexion/extension, abduction/adduction, circumduction, and medial/lateral rotation movements Shoulder and hip joints Table 9.1 9.6 Anatomy of Selected Synovial Joints Learning Objectives By the end of this section, you will be able to: Describe the bones that articulate together to form selected synovial joints Discuss the movements available at each joint Describe the structures that support and prevent excess movements at each joint Each synovial joint of the body is specialized to perform certain movements. The movements that are allowed are determined by the structural classification for each joint. For example, a multiaxial ball-and-socket joint has much more mobility than a uniaxial hinge joint. However, the ligaments and muscles that support a joint may place restrictions on the total range of motion available. Thus, the ball-and-socket joint of the shoulder has little in the way of ligament support, which gives the shoulder a very large range of motion. In contrast, movements at the hip joint are restricted by strong ligaments, which reduce its range of motion but confer stability during standing and weight bearing. This section will examine the anatomy of selected synovial joints of the body. Anatomical names for most joints are derived from the names of the bones that articulate at that joint, although some joints, such as the elbow, hip, and knee joints are exceptions to this general naming scheme. Articulations of the Vertebral Column In addition to being held together by the intervertebral discs, adjacent vertebrae also articulate with each other at synovial joints formed between the superior and inferior articular processes called zygapophysial joints (facet joints) (see Figure 9.3 ). These are plane joints that provide for only limited motions between the vertebrae. The orientation of the articular processes at these joints varies in different regions of the vertebral column and serves to determine the types of motions available in each vertebral region. The cervical and lumbar regions have the greatest ranges of motions. In the neck, the articular processes of cervical vertebrae are flattened and generally face upward or downward. This orientation provides the cervical vertebral column with extensive ranges of motion for flexion, extension, lateral flexion, and rotation. In the thoracic region, the downward projecting and overlapping spinous processes, along with the attached thoracic cage, greatly limit flexion, extension, and lateral flexion. However, the flattened and vertically positioned thoracic articular processes allow for the greatest range of rotation within the vertebral column. The lumbar region allows for considerable extension, flexion, and lateral flexion, but the orientation of the articular processes largely prohibits rotation. The articulations formed between the skull, the atlas (C1 vertebra), and the axis (C2 vertebra) differ from the articulations in other vertebral areas and play important roles in movement of the head. The atlanto-occipital joint is formed by the articulations between the superior articular processes of the atlas and the occipital condyles on the base of the skull. This articulation has a pronounced U-shaped curvature, oriented along the anterior-posterior axis. This allows the skull to rock forward and backward, producing flexion and extension of the head. This moves the head up and down, as when shaking your head “yes.” The atlantoaxial joint , between the atlas and axis, consists of three articulations. The paired superior articular processes of the axis articulate with the inferior articular processes of the atlas. These articulating surfaces are relatively flat and oriented horizontally. The third articulation is the pivot joint formed between the dens, which projects upward from the body of the axis, and the inner aspect of the anterior arch of the atlas ( Figure 9.14 ). A strong ligament passes posterior to the dens to hold it in position against the anterior arch. These articulations allow the atlas to rotate on top of the axis, moving the head toward the right or left, as when shaking your head “no.” Temporomandibular Joint The temporomandibular joint (TMJ) is the joint that allows for opening (mandibular depression) and closing (mandibular elevation) of the mouth, as well as side-to-side and protraction/retraction motions of the lower jaw. This joint involves the articulation between the mandibular fossa and articular tubercle of the temporal bone, with the condyle (head) of the mandible. Located between these bony structures, filling the gap between the skull and mandible, is a flexible articular disc ( Figure 9.15 ). This disc serves to smooth the movements between the temporal bone and mandibular condyle. Movement at the TMJ during opening and closing of the mouth involves both gliding and hinge motions of the mandible. With the mouth closed, the mandibular condyle and articular disc are located within the mandibular fossa of the temporal bone. During opening of the mouth, the mandible hinges downward and at the same time is pulled anteriorly, causing both the condyle and the articular disc to glide forward from the mandibular fossa onto the downward projecting articular tubercle. The net result is a forward and downward motion of the condyle and mandibular depression. The temporomandibular joint is supported by an extrinsic ligament that anchors the mandible to the skull. This ligament spans the distance between the base of the skull and the lingula on the medial side of the mandibular ramus. Dislocation of the TMJ may occur when opening the mouth too wide (such as when taking a large bite) or following a blow to the jaw, resulting in the mandibular condyle moving beyond (anterior to) the articular tubercle. In this case, the individual would not be able to close his or her mouth. Temporomandibular joint disorder is a painful condition that may arise due to arthritis, wearing of the articular cartilage covering the bony surfaces of the joint, muscle fatigue from overuse or grinding of the teeth, damage to the articular disc within the joint, or jaw injury. Temporomandibular joint disorders can also cause headache, difficulty chewing, or even the inability to move the jaw (lock jaw). Pharmacologic agents for pain or other therapies, including bite guards, are used as treatments. Interactive Link Watch this video to learn about TMJ. Opening of the mouth requires the combination of two motions at the temporomandibular joint, an anterior gliding motion of the articular disc and mandible and the downward hinging of the mandible. What is the initial movement of the mandible during opening and how much mouth opening does this produce? Shoulder Joint The shoulder joint is called the glenohumeral joint . This is a ball-and-socket joint formed by the articulation between the head of the humerus and the glenoid cavity of the scapula ( Figure 9.16 ). This joint has the largest range of motion of any joint in the body. However, this freedom of movement is due to the lack of structural support and thus the enhanced mobility is offset by a loss of stability. The large range of motions at the shoulder joint is provided by the articulation of the large, rounded humeral head with the small and shallow glenoid cavity, which is only about one third of the size of the humeral head. The socket formed by the glenoid cavity is deepened slightly by a small lip of fibrocartilage called the glenoid labrum , which extends around the outer margin of the cavity. The articular capsule that surrounds the glenohumeral joint is relatively thin and loose to allow for large motions of the upper limb. Some structural support for the joint is provided by thickenings of the articular capsule wall that form weak intrinsic ligaments. These include the coracohumeral ligament , running from the coracoid process of the scapula to the anterior humerus, and three ligaments, each called a glenohumeral ligament , located on the anterior side of the articular capsule. These ligaments help to strengthen the superior and anterior capsule walls. However, the primary support for the shoulder joint is provided by muscles crossing the joint, particularly the four rotator cuff muscles. These muscles (supraspinatus, infraspinatus, teres minor, and subscapularis) arise from the scapula and attach to the greater or lesser tubercles of the humerus. As these muscles cross the shoulder joint, their tendons encircle the head of the humerus and become fused to the anterior, superior, and posterior walls of the articular capsule. The thickening of the capsule formed by the fusion of these four muscle tendons is called the rotator cuff . Two bursae, the subacromial bursa and the subscapular bursa , help to prevent friction between the rotator cuff muscle tendons and the scapula as these tendons cross the glenohumeral joint. In addition to their individual actions of moving the upper limb, the rotator cuff muscles also serve to hold the head of the humerus in position within the glenoid cavity. By constantly adjusting their strength of contraction to resist forces acting on the shoulder, these muscles serve as “dynamic ligaments” and thus provide the primary structural support for the glenohumeral joint. Injuries to the shoulder joint are common. Repetitive use of the upper limb, particularly in abduction such as during throwing, swimming, or racquet sports, may lead to acute or chronic inflammation of the bursa or muscle tendons, a tear of the glenoid labrum, or degeneration or tears of the rotator cuff. Because the humeral head is strongly supported by muscles and ligaments around its anterior, superior, and posterior aspects, most dislocations of the humerus occur in an inferior direction. This can occur when force is applied to the humerus when the upper limb is fully abducted, as when diving to catch a baseball and landing on your hand or elbow. Inflammatory responses to any shoulder injury can lead to the formation of scar tissue between the articular capsule and surrounding structures, thus reducing shoulder mobility, a condition called adhesive capsulitis (“frozen shoulder”). Interactive Link Watch this video for a tutorial on the anatomy of the shoulder joint. What movements are available at the shoulder joint? Interactive Link Watch this video to learn more about the anatomy of the shoulder joint, including bones, joints, muscles, nerves, and blood vessels. What is the shape of the glenoid labrum in cross-section, and what is the importance of this shape? Elbow Joint The elbow joint is a uniaxial hinge joint formed by the humeroulnar joint , the articulation between the trochlea of the humerus and the trochlear notch of the ulna. Also associated with the elbow are the humeroradial joint and the proximal radioulnar joint. All three of these joints are enclosed within a single articular capsule ( Figure 9.17 ). The articular capsule of the elbow is thin on its anterior and posterior aspects, but is thickened along its outside margins by strong intrinsic ligaments. These ligaments prevent side-to-side movements and hyperextension. On the medial side is the triangular ulnar collateral ligament . This arises from the medial epicondyle of the humerus and attaches to the medial side of the proximal ulna. The strongest part of this ligament is the anterior portion, which resists hyperextension of the elbow. The ulnar collateral ligament may be injured by frequent, forceful extensions of the forearm, as is seen in baseball pitchers. Reconstructive surgical repair of this ligament is referred to as Tommy John surgery, named for the former major league pitcher who was the first person to have this treatment. The lateral side of the elbow is supported by the radial collateral ligament . This arises from the lateral epicondyle of the humerus and then blends into the lateral side of the annular ligament. The annular ligament encircles the head of the radius. This ligament supports the head of the radius as it articulates with the radial notch of the ulna at the proximal radioulnar joint. This is a pivot joint that allows for rotation of the radius during supination and pronation of the forearm. Interactive Link Watch this animation to learn more about the anatomy of the elbow joint. Which structures provide the main stability for the elbow? Interactive Link Watch this video to learn more about the anatomy of the elbow joint, including bones, joints, muscles, nerves, and blood vessels. What are the functions of the articular cartilage? Hip Joint The hip joint is a multiaxial ball-and-socket joint between the head of the femur and the acetabulum of the hip bone ( Figure 9.18 ). The hip carries the weight of the body and thus requires strength and stability during standing and walking. For these reasons, its range of motion is more limited than at the shoulder joint. The acetabulum is the socket portion of the hip joint. This space is deep and has a large articulation area for the femoral head, thus giving stability and weight bearing ability to the joint. The acetabulum is further deepened by the acetabular labrum , a fibrocartilage lip attached to the outer margin of the acetabulum. The surrounding articular capsule is strong, with several thickened areas forming intrinsic ligaments. These ligaments arise from the hip bone, at the margins of the acetabulum, and attach to the femur at the base of the neck. The ligaments are the iliofemoral ligament , pubofemoral ligament , and ischiofemoral ligament , all of which spiral around the head and neck of the femur. The ligaments are tightened by extension at the hip, thus pulling the head of the femur tightly into the acetabulum when in the upright, standing position. Very little additional extension of the thigh is permitted beyond this vertical position. These ligaments thus stabilize the hip joint and allow you to maintain an upright standing position with only minimal muscle contraction. Inside of the articular capsule, the ligament of the head of the femur (ligamentum teres) spans between the acetabulum and femoral head. This intracapsular ligament is normally slack and does not provide any significant joint support, but it does provide a pathway for an important artery that supplies the head of the femur. The hip is prone to osteoarthritis, and thus was the first joint for which a replacement prosthesis was developed. A common injury in elderly individuals, particularly those with weakened bones due to osteoporosis, is a “broken hip,” which is actually a fracture of the femoral neck. This may result from a fall, or it may cause the fall. This can happen as one lower limb is taking a step and all of the body weight is placed on the other limb, causing the femoral neck to break and producing a fall. Any accompanying disruption of the blood supply to the femoral neck or head can lead to necrosis of these areas, resulting in bone and cartilage death. Femoral fractures usually require surgical treatment, after which the patient will need mobility assistance for a prolonged period, either from family members or in a long-term care facility. Consequentially, the associated health care costs of “broken hips” are substantial. In addition, hip fractures are associated with increased rates of morbidity (incidences of disease) and mortality (death). Surgery for a hip fracture followed by prolonged bed rest may lead to life-threatening complications, including pneumonia, infection of pressure ulcers (bedsores), and thrombophlebitis (deep vein thrombosis; blood clot formation) that can result in a pulmonary embolism (blood clot within the lung). Interactive Link Watch this video for a tutorial on the anatomy of the hip joint. What is a possible consequence following a fracture of the femoral neck within the capsule of the hip joint? Interactive Link Watch this video to learn more about the anatomy of the hip joint, including bones, joints, muscles, nerves, and blood vessels. Where is the articular cartilage thickest within the hip joint? Knee Joint The knee joint is the largest joint of the body ( Figure 9.19 ). It actually consists of three articulations. The femoropatellar joint is found between the patella and the distal femur. The medial tibiofemoral joint and lateral tibiofemoral joint are located between the medial and lateral condyles of the femur and the medial and lateral condyles of the tibia. All of these articulations are enclosed within a single articular capsule. The knee functions as a hinge joint, allowing flexion and extension of the leg. This action is generated by both rolling and gliding motions of the femur on the tibia. In addition, some rotation of the leg is available when the knee is flexed, but not when extended. The knee is well constructed for weight bearing in its extended position, but is vulnerable to injuries associated with hyperextension, twisting, or blows to the medial or lateral side of the joint, particularly while weight bearing. At the femoropatellar joint, the patella slides vertically within a groove on the distal femur. The patella is a sesamoid bone incorporated into the tendon of the quadriceps femoris muscle, the large muscle of the anterior thigh. The patella serves to protect the quadriceps tendon from friction against the distal femur. Continuing from the patella to the anterior tibia just below the knee is the patellar ligament . Acting via the patella and patellar ligament, the quadriceps femoris is a powerful muscle that acts to extend the leg at the knee. It also serves as a “dynamic ligament” to provide very important support and stabilization for the knee joint. The medial and lateral tibiofemoral joints are the articulations between the rounded condyles of the femur and the relatively flat condyles of the tibia. During flexion and extension motions, the condyles of the femur both roll and glide over the surfaces of the tibia. The rolling action produces flexion or extension, while the gliding action serves to maintain the femoral condyles centered over the tibial condyles, thus ensuring maximal bony, weight-bearing support for the femur in all knee positions. As the knee comes into full extension, the femur undergoes a slight medial rotation in relation to tibia. The rotation results because the lateral condyle of the femur is slightly smaller than the medial condyle. Thus, the lateral condyle finishes its rolling motion first, followed by the medial condyle. The resulting small medial rotation of the femur serves to “lock” the knee into its fully extended and most stable position. Flexion of the knee is initiated by a slight lateral rotation of the femur on the tibia, which “unlocks” the knee. This lateral rotation motion is produced by the popliteus muscle of the posterior leg. Located between the articulating surfaces of the femur and tibia are two articular discs, the medial meniscus and lateral meniscus (see Figure 9.19 b ). Each is a C-shaped fibrocartilage structure that is thin along its inside margin and thick along the outer margin. They are attached to their tibial condyles, but do not attach to the femur. While both menisci are free to move during knee motions, the medial meniscus shows less movement because it is anchored at its outer margin to the articular capsule and tibial collateral ligament. The menisci provide padding between the bones and help to fill the gap between the round femoral condyles and flattened tibial condyles. Some areas of each meniscus lack an arterial blood supply and thus these areas heal poorly if damaged. The knee joint has multiple ligaments that provide support, particularly in the extended position (see Figure 9.19 c ). Outside of the articular capsule, located at the sides of the knee, are two extrinsic ligaments. The fibular collateral ligament (lateral collateral ligament) is on the lateral side and spans from the lateral epicondyle of the femur to the head of the fibula. The tibial collateral ligament (medial collateral ligament) of the medial knee runs from the medial epicondyle of the femur to the medial tibia. As it crosses the knee, the tibial collateral ligament is firmly attached on its deep side to the articular capsule and to the medial meniscus, an important factor when considering knee injuries. In the fully extended knee position, both collateral ligaments are taut (tight), thus serving to stabilize and support the extended knee and preventing side-to-side or rotational motions between the femur and tibia. The articular capsule of the posterior knee is thickened by intrinsic ligaments that help to resist knee hyperextension. Inside the knee are two intracapsular ligaments, the anterior cruciate ligament and posterior cruciate ligament . These ligaments are anchored inferiorly to the tibia at the intercondylar eminence, the roughened area between the tibial condyles. The cruciate ligaments are named for whether they are attached anteriorly or posteriorly to this tibial region. Each ligament runs diagonally upward to attach to the inner aspect of a femoral condyle. The cruciate ligaments are named for the X-shape formed as they pass each other (cruciate means “cross”). The posterior cruciate ligament is the stronger ligament. It serves to support the knee when it is flexed and weight bearing, as when walking downhill. In this position, the posterior cruciate ligament prevents the femur from sliding anteriorly off the top of the tibia. The anterior cruciate ligament becomes tight when the knee is extended, and thus resists hyperextension. Interactive Link Watch this video to learn more about the flexion and extension of the knee, as the femur both rolls and glides on the tibia to maintain stable contact between the bones in all knee positions. The patella glides along a groove on the anterior side of the distal femur. The collateral ligaments on the sides of the knee become tight in the fully extended position to help stabilize the knee. The posterior cruciate ligament supports the knee when flexed and the anterior cruciate ligament becomes tight when the knee comes into full extension to resist hyperextension. What are the ligaments that support the knee joint? Interactive Link Watch this video to learn more about the anatomy of the knee joint, including bones, joints, muscles, nerves, and blood vessels. Which ligament of the knee keeps the tibia from sliding too far forward in relation to the femur and which ligament keeps the tibia from sliding too far backward? Disorders of the... Joints Injuries to the knee are common. Since this joint is primarily supported by muscles and ligaments, injuries to any of these structures will result in pain or knee instability. Injury to the posterior cruciate ligament occurs when the knee is flexed and the tibia is driven posteriorly, such as falling and landing on the tibial tuberosity or hitting the tibia on the dashboard when not wearing a seatbelt during an automobile accident. More commonly, injuries occur when forces are applied to the extended knee, particularly when the foot is planted and unable to move. Anterior cruciate ligament injuries can result with a forceful blow to the anterior knee, producing hyperextension, or when a runner makes a quick change of direction that produces both twisting and hyperextension of the knee. A worse combination of injuries can occur with a hit to the lateral side of the extended knee ( Figure 9.20 ). A moderate blow to the lateral knee will cause the medial side of the joint to open, resulting in stretching or damage to the tibial collateral ligament. Because the medial meniscus is attached to the tibial collateral ligament, a stronger blow can tear the ligament and also damage the medial meniscus. This is one reason that the medial meniscus is 20 times more likely to be injured than the lateral meniscus. A powerful blow to the lateral knee produces a “terrible triad” injury, in which there is a sequential injury to the tibial collateral ligament, medial meniscus, and anterior cruciate ligament. Arthroscopic surgery has greatly improved the surgical treatment of knee injuries and reduced subsequent recovery times. This procedure involves a small incision and the insertion into the joint of an arthroscope, a pencil-thin instrument that allows for visualization of the joint interior. Small surgical instruments are also inserted via additional incisions. These tools allow a surgeon to remove or repair a torn meniscus or to reconstruct a ruptured cruciate ligament. The current method for anterior cruciate ligament replacement involves using a portion of the patellar ligament. Holes are drilled into the cruciate ligament attachment points on the tibia and femur, and the patellar ligament graft, with small areas of attached bone still intact at each end, is inserted into these holes. The bone-to-bone sites at each end of the graft heal rapidly and strongly, thus enabling a rapid recovery. Interactive Link Watch this video to learn more about different knee injuries and diagnostic testing of the knee. What are the most common causes of anterior cruciate ligament injury? Ankle and Foot Joints The ankle is formed by the talocrural joint ( Figure 9.21 ). It consists of the articulations between the talus bone of the foot and the distal ends of the tibia and fibula of the leg (crural = “leg”). The superior aspect of the talus bone is square-shaped and has three areas of articulation. The top of the talus articulates with the inferior tibia. This is the portion of the ankle joint that carries the body weight between the leg and foot. The sides of the talus are firmly held in position by the articulations with the medial malleolus of the tibia and the lateral malleolus of the fibula, which prevent any side-to-side motion of the talus. The ankle is thus a uniaxial hinge joint that allows only for dorsiflexion and plantar flexion of the foot. Additional joints between the tarsal bones of the posterior foot allow for the movements of foot inversion and eversion. Most important for these movements is the subtalar joint , located between the talus and calcaneus bones. The joints between the talus and navicular bones and the calcaneus and cuboid bones are also important contributors to these movements. All of the joints between tarsal bones are plane joints. Together, the small motions that take place at these joints all contribute to the production of inversion and eversion foot motions. Like the hinge joints of the elbow and knee, the talocrural joint of the ankle is supported by several strong ligaments located on the sides of the joint. These ligaments extend from the medial malleolus of the tibia or lateral malleolus of the fibula and anchor to the talus and calcaneus bones. Since they are located on the sides of the ankle joint, they allow for dorsiflexion and plantar flexion of the foot. They also prevent abnormal side-to-side and twisting movements of the talus and calcaneus bones during eversion and inversion of the foot. On the medial side is the broad deltoid ligament . The deltoid ligament supports the ankle joint and also resists excessive eversion of the foot. The lateral side of the ankle has several smaller ligaments. These include the anterior talofibular ligament and the posterior talofibular ligament , both of which span between the talus bone and the lateral malleolus of the fibula, and the calcaneofibular ligament , located between the calcaneus bone and fibula. These ligaments support the ankle and also resist excess inversion of the foot. Interactive Link Watch this video for a tutorial on the anatomy of the ankle joint. What are the three ligaments found on the lateral side of the ankle joint? Interactive Link Watch this video to learn more about the anatomy of the ankle joint, including bones, joints, muscles, nerves, and blood vessels. Which type of joint used in woodworking does the ankle joint resemble? Disorders of the... Joints The ankle is the most frequently injured joint in the body, with the most common injury being an inversion ankle sprain. A sprain is the stretching or tearing of the supporting ligaments. Excess inversion causes the talus bone to tilt laterally, thus damaging the ligaments on the lateral side of the ankle. The anterior talofibular ligament is most commonly injured, followed by the calcaneofibular ligament. In severe inversion injuries, the forceful lateral movement of the talus not only ruptures the lateral ankle ligaments, but also fractures the distal fibula. Less common are eversion sprains of the ankle, which involve stretching of the deltoid ligament on the medial side of the ankle. Forcible eversion of the foot, for example, with an awkward landing from a jump or when a football player has a foot planted and is hit on the lateral ankle, can result in a Pott’s fracture and dislocation of the ankle joint. In this injury, the very strong deltoid ligament does not tear, but instead shears off the medial malleolus of the tibia. This frees the talus, which moves laterally and fractures the distal fibula. In extreme cases, the posterior margin of the tibia may also be sheared off. Above the ankle, the distal ends of the tibia and fibula are united by a strong syndesmosis formed by the interosseous membrane and ligaments at the distal tibiofibular joint. These connections prevent separation between the distal ends of the tibia and fibula and maintain the talus locked into position between the medial malleolus and lateral malleolus. Injuries that produce a lateral twisting of the leg on top of the planted foot can result in stretching or tearing of the tibiofibular ligaments, producing a syndesmotic ankle sprain or “high ankle sprain.” Most ankle sprains can be treated using the RICE technique: Rest, Ice, Compression, and Elevation. Reducing joint mobility using a brace or cast may be required for a period of time. More severe injuries involving ligament tears or bone fractures may require surgery. Interactive Link Watch this video to learn more about the ligaments of the ankle joint, ankle sprains, and treatment. During an inversion ankle sprain injury, all three ligaments that resist excessive inversion of the foot may be injured. What is the sequence in which these three ligaments are injured? 9.7 Development of Joints Learning Objectives By the end of this section, you will be able to: Describe the two processes by which mesenchyme can give rise to bone Discuss the process by which joints of the limbs are formed Joints form during embryonic development in conjunction with the formation and growth of the associated bones. The embryonic tissue that gives rise to all bones, cartilages, and connective tissues of the body is called mesenchyme. In the head, mesenchyme will accumulate at those areas that will become the bones that form the top and sides of the skull. The mesenchyme in these areas will develop directly into bone through the process of intramembranous ossification, in which mesenchymal cells differentiate into bone-producing cells that then generate bone tissue. The mesenchyme between the areas of bone production will become the fibrous connective tissue that fills the spaces between the developing bones. Initially, the connective tissue-filled gaps between the bones are wide, and are called fontanelles. After birth, as the skull bones grow and enlarge, the gaps between them decrease in width and the fontanelles are reduced to suture joints in which the bones are united by a narrow layer of fibrous connective tissue. The bones that form the base and facial regions of the skull develop through the process of endochondral ossification. In this process, mesenchyme accumulates and differentiates into hyaline cartilage, which forms a model of the future bone. The hyaline cartilage model is then gradually, over a period of many years, displaced by bone. The mesenchyme between these developing bones becomes the fibrous connective tissue of the suture joints between the bones in these regions of the skull. A similar process of endochondral ossification gives rises to the bones and joints of the limbs. The limbs initially develop as small limb buds that appear on the sides of the embryo around the end of the fourth week of development. Starting during the sixth week, as each limb bud continues to grow and elongate, areas of mesenchyme within the bud begin to differentiate into the hyaline cartilage that will form models for of each of the future bones. The synovial joints will form between the adjacent cartilage models, in an area called the joint interzone . Cells at the center of this interzone region undergo cell death to form the joint cavity, while surrounding mesenchyme cells will form the articular capsule and supporting ligaments. The process of endochondral ossification, which converts the cartilage models into bone, begins by the twelfth week of embryonic development. At birth, ossification of much of the bone has occurred, but the hyaline cartilage of the epiphyseal plate will remain throughout childhood and adolescence to allow for bone lengthening. Hyaline cartilage is also retained as the articular cartilage that covers the surfaces of the bones at synovial joints.
biology
Chapter Outline 27.1 Features of the Animal Kingdom 27.2 Features Used to Classify Animals 27.3 Animal Phylogeny 27.4 The Evolutionary History of the Animal Kingdom Introduction Animal evolution began in the ocean over 600 million years ago with tiny creatures that probably do not resemble any living organism today. Since then, animals have evolved into a highly diverse kingdom. Although over one million extant (currently living) species of animals have been identified, scientists are continually discovering more species as they explore ecosystems around the world. The number of extant species is estimated to be between 3 and 30 million. But what is an animal? While we can easily identify dogs, birds, fish, spiders, and worms as animals, other organisms, such as corals and sponges, are not as easy to classify. Animals vary in complexity—from sea sponges to crickets to chimpanzees—and scientists are faced with the difficult task of classifying them within a unified system. They must identify traits that are common to all animals as well as traits that can be used to distinguish among related groups of animals. The animal classification system characterizes animals based on their anatomy, morphology, evolutionary history, features of embryological development, and genetic makeup. This classification scheme is constantly developing as new information about species arises. Understanding and classifying the great variety of living species help us better understand how to conserve the diversity of life on earth.
[ { "answer": { "ans_choice": 1, "ans_text": "asexual reproduction" }, "bloom": null, "hl_context": "<hl> Most animals are diploid organisms , meaning that their body ( somatic ) cells are diploid and haploid reproductive ( gamete ) cells are produced through meiosis . <hl> Some exceptions exist : For example , in bees , wasps , and ants , the male is haploid because it develops from unfertilized eggs . <hl> Most animals undergo sexual reproduction : This fact distinguishes animals from fungi , protists , and bacteria , where asexual reproduction is common or exclusive . <hl> <hl> However , a few groups , such as cnidarians , flatworm , and roundworms , undergo asexual reproduction , although nearly all of those animals also have a sexual phase to their life cycle . <hl>", "hl_sentences": "Most animals are diploid organisms , meaning that their body ( somatic ) cells are diploid and haploid reproductive ( gamete ) cells are produced through meiosis . Most animals undergo sexual reproduction : This fact distinguishes animals from fungi , protists , and bacteria , where asexual reproduction is common or exclusive . However , a few groups , such as cnidarians , flatworm , and roundworms , undergo asexual reproduction , although nearly all of those animals also have a sexual phase to their life cycle .", "question": { "cloze_format": "(The) ___ is not a feature common to most animals.", "normal_format": "Which of the following is not a feature common to most animals?", "question_choices": [ "development into a fixed body plan", "asexual reproduction", "specialized tissues", "heterotrophic nutrient sourcing" ], "question_id": "fs-idm52700048", "question_text": "Which of the following is not a feature common to most animals?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 2, "ans_text": "the gastrula stage" }, "bloom": null, "hl_context": "The process of animal development begins with the cleavage , or series of mitotic cell divisions , of the zygote ( Figure 27.4 ) . Three cell divisions transform the single-celled zygote into an eight-celled structure . After further cell division and rearrangement of existing cells , a 6 – 32 - celled hollow structure called a blastula is formed . Next , the blastula undergoes further cell division and cellular rearrangement during a process called gastrulation . <hl> This leads to the formation of the next developmental stage , the gastrula , in which the future digestive cavity is formed . <hl> <hl> Different cell layers ( called germ layers ) are formed during gastrulation . <hl> <hl> These germ layers are programmed to develop into certain tissue types , organs , and organ systems during a process called organogenesis . <hl>", "hl_sentences": "This leads to the formation of the next developmental stage , the gastrula , in which the future digestive cavity is formed . Different cell layers ( called germ layers ) are formed during gastrulation . These germ layers are programmed to develop into certain tissue types , organs , and organ systems during a process called organogenesis .", "question": { "cloze_format": "During embryonic development, unique cell layers develop and distinguish during a stage called ________.", "normal_format": "During embryonic development, unique cell layers develop and distinguish during which stage?", "question_choices": [ "the blastula stage", "the germ layer stage", "the gastrula stage", "the organogenesis stage" ], "question_id": "fs-idm67872016", "question_text": "During embryonic development, unique cell layers develop and distinguish during a stage called ________." }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 3, "ans_text": "two fewer appendages than normal" }, "bloom": null, "hl_context": "Since the early 19 th century , scientists have observed that many animals , from the very simple to the complex , shared similar embryonic morphology and development . Surprisingly , a human embryo and a frog embryo , at a certain stage of embryonic development , look remarkably alike . For a long time , scientists did not understand why so many animal species looked similar during embryonic development but were very different as adults . They wondered what dictated the developmental direction that a fly , mouse , frog , or human embryo would take . Near the end of the 20 th century , a particular class of genes was discovered that had this very job . These genes that determine animal structure are called “ homeotic genes , ” and they contain DNA sequences called homeoboxes . <hl> The animal genes containing homeobox sequences are specifically referred to as Hox genes . <hl> <hl> This family of genes is responsible for determining the general body plan , such as the number of body segments of an animal , the number and placement of appendages , and animal head-tail directionality . <hl> The first Hox genes to be sequenced were those from the fruit fly ( Drosophila melanogaster ) . <hl> A single Hox mutation in the fruit fly can result in an extra pair of wings or even appendages growing from the “ wrong ” body part . <hl>", "hl_sentences": "The animal genes containing homeobox sequences are specifically referred to as Hox genes . This family of genes is responsible for determining the general body plan , such as the number of body segments of an animal , the number and placement of appendages , and animal head-tail directionality . A single Hox mutation in the fruit fly can result in an extra pair of wings or even appendages growing from the “ wrong ” body part .", "question": { "cloze_format": "The phenotype that would most likely be the result of a Hox gene mutation, is ___.", "normal_format": "Which of the following phenotypes would most likely be the result of a Hox gene mutation?", "question_choices": [ "abnormal body length or height", "two different eye colors", "the contraction of a genetic illness", "two fewer appendages than normal" ], "question_id": "fs-idm35006192", "question_text": "Which of the following phenotypes would most likely be the result of a Hox gene mutation?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 2, "ans_text": "jellyfish" }, "bloom": "2", "hl_context": "One of the first steps in the classification of animals is to examine the animal ’ s body . Studying the body parts tells us not only the roles of the organs in question but also how the species may have evolved . One such structure that is used in classification of animals is the coelom . A coelom is a body cavity that forms during early embryonic development . <hl> The coelom allows for compartmentalization of the body parts , so that different organ systems can evolve and nutrient transport is possible . <hl> <hl> Additionally , because the coelom is a fluid-filled cavity , it protects the organs from shock and compression . <hl> <hl> Simple animals , such as worms and jellyfish , do not have a coelom . <hl> All vertebrates have a coelom that helped them evolve complex organ systems . <hl> Most animal species undergo a separation of tissues into germ layers during embryonic development . <hl> Recall that these germ layers are formed during gastrulation , and that they are predetermined to develop into the animal ’ s specialized tissues and organs . <hl> Animals develop either two or three embryonic germs layers ( Figure 27.9 ) . <hl> <hl> The animals that display radial symmetry develop two germ layers , an inner layer ( endoderm ) and an outer layer ( ectoderm ) . <hl> <hl> These animals are called diploblasts . <hl> Diploblasts have a non-living layer between the endoderm and ectoderm . More complex animals ( those with bilateral symmetry ) develop three tissue layers : an inner layer ( endoderm ) , an outer layer ( ectoderm ) , and a middle layer ( mesoderm ) . Animals with three tissue layers are called triploblasts .", "hl_sentences": "The coelom allows for compartmentalization of the body parts , so that different organ systems can evolve and nutrient transport is possible . Additionally , because the coelom is a fluid-filled cavity , it protects the organs from shock and compression . Simple animals , such as worms and jellyfish , do not have a coelom . Most animal species undergo a separation of tissues into germ layers during embryonic development . Animals develop either two or three embryonic germs layers ( Figure 27.9 ) . The animals that display radial symmetry develop two germ layers , an inner layer ( endoderm ) and an outer layer ( ectoderm ) . These animals are called diploblasts .", "question": { "cloze_format": "The organism that is most likely to be a diploblast is a ___.", "normal_format": "Which of the following organism is most likely to be a diploblast?", "question_choices": [ "sea star", "shrimp", "jellyfish", "insect" ], "question_id": "fs-idp100481456", "question_text": "Which of the following organism is most likely to be a diploblast?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 1, "ans_text": "diploblastic eucoelomate" }, "bloom": "3", "hl_context": "<hl> Animals that have a true coelom are called eucoelomates ; all vertebrates are eucoelomates . <hl> The coelom evolves from the mesoderm during embryogenesis . The abdominal cavity contains the stomach , liver , gall bladder , and other digestive organs . Another category of invertebrates animals based on body cavity is pseudocoelomates . These animals have a pseudo-cavity that is not completely lined by mesoderm . Examples include nematode parasites and small worms . These animals are thought to have evolved from coelomates and may have lost their ability to form a coelom through genetic mutations . Thus , this step in early embryogenesis — the formation of the coelom — has had a large evolutionary impact on the various species of the animal kingdom . 27.3 Animal Phylogeny Learning Objectives By the end of this section , you will be able to : Most animal species undergo a separation of tissues into germ layers during embryonic development . Recall that these germ layers are formed during gastrulation , and that they are predetermined to develop into the animal ’ s specialized tissues and organs . Animals develop either two or three embryonic germs layers ( Figure 27.9 ) . <hl> The animals that display radial symmetry develop two germ layers , an inner layer ( endoderm ) and an outer layer ( ectoderm ) . <hl> <hl> These animals are called diploblasts . <hl> Diploblasts have a non-living layer between the endoderm and ectoderm . More complex animals ( those with bilateral symmetry ) develop three tissue layers : an inner layer ( endoderm ) , an outer layer ( ectoderm ) , and a middle layer ( mesoderm ) . Animals with three tissue layers are called triploblasts .", "hl_sentences": "Animals that have a true coelom are called eucoelomates ; all vertebrates are eucoelomates . The animals that display radial symmetry develop two germ layers , an inner layer ( endoderm ) and an outer layer ( ectoderm ) . These animals are called diploblasts .", "question": { "cloze_format": "A ___ is not possible.", "normal_format": "Which of the following is not possible?", "question_choices": [ "radially symmetrical diploblast", "diploblastic eucoelomate", "protostomic coelomate", "bilaterally symmetrical deuterostome" ], "question_id": "fs-idp153075280", "question_text": "Which of the following is not possible?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 0, "ans_text": "a deuterostome" }, "bloom": null, "hl_context": "The earliest distinction between protostomes and deuterostomes is the type of cleavage undergone by the zygote . Protostomes undergo spiral cleavage , meaning that the cells of one pole of the embryo are rotated , and thus misaligned , with respect to the cells of the opposite pole . This is due to the oblique angle of the cleavage . <hl> Deuterostomes undergo radial cleavage , where the cleavage axes are either parallel or perpendicular to the polar axis , resulting in the alignment of the cells between the two poles . <hl> Bilaterally symmetrical , triploblastic eucoelomates can be further divided into two groups based on differences in their early embryonic development . Protostomes include arthropods , mollusks , and annelids . Deuterostomes include more complex animals such as chordates but also some simple animals such as echinoderms . These two groups are separated based on which opening of the digestive cavity develops first : mouth or anus . The word protostome comes from the Greek word meaning “ mouth first , ” and deuterostome originates from the word meaning “ mouth second ” ( in this case , the anus develops first ) . The mouth or anus develops from a structure called the blastopore ( Figure 27.11 ) . The blastopore is the indentation formed during the initial stages of gastrulation . In later stages , a second opening forms , and these two openings will eventually give rise to the mouth and anus ( Figure 27.11 ) . It has long been believed that the blastopore develops into the mouth of protostomes , with the second opening developing into the anus ; the opposite is true for deuterostomes . Recent evidence has challenged this view of the development of the blastopore of protostomes , however , and the theory remains under debate . Another distinction between protostomes and deuterostomes is the method of coelom formation , beginning from the gastrula stage . The coelom of most protostomes is formed through a process called schizocoely , meaning that during development , a solid mass of the mesoderm splits apart and forms the hollow opening of the coelom . <hl> Deuterostomes differ in that their coelom forms through a process called enterocoely . <hl> Here , the mesoderm develops as pouches that are pinched off from the endoderm tissue . These pouches eventually fuse to form the mesoderm , which then gives rise to the coelom .", "hl_sentences": "Deuterostomes undergo radial cleavage , where the cleavage axes are either parallel or perpendicular to the polar axis , resulting in the alignment of the cells between the two poles . Deuterostomes differ in that their coelom forms through a process called enterocoely .", "question": { "cloze_format": "An animal whose development is marked by radial cleavage and enterocoely is ________.", "normal_format": "What is an animal whose development is marked by radial cleavage and enterocoely?", "question_choices": [ "a deuterostome", "an annelid or mollusk", "either an acoelomate or eucoelomate", "none of the above" ], "question_id": "fs-idp176361680", "question_text": "An animal whose development is marked by radial cleavage and enterocoely is ________." }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 2, "ans_text": "Parazoa" }, "bloom": "3", "hl_context": "Watch the following video to learn how biologists use genetic data to determine relationships among organisms . <hl> Nucleic acid and protein analyses have greatly informed the modern phylogenetic animal tree . <hl> These data come from a variety of molecular sources , such as mitochondrial DNA , nuclear DNA , ribosomal RNA ( rRNA ) , and certain cellular proteins . <hl> Many evolutionary relationships in the modern tree have only recently been determined due to molecular evidence . <hl> <hl> For example , a previously classified group of animals called lophophorates , which included brachiopods and bryozoans , were long-thought to be primitive deuterostomes . <hl> Extensive molecular analysis using rRNA data found these animals to be protostomes , more closely related to annelids and mollusks . <hl> This discovery allowed for the distinction of the protostome clade , the lophotrochozoans . <hl> Molecular data have also shed light on some differences within the lophotrochozoan group , and some scientists believe that the phyla Platyhelminthes and Rotifera within this group should actually belong to their own group of protostomes termed Platyzoa . <hl> Eumetazoa are subdivided into radially symmetrical animals and bilaterally symmetrical animals , and are thus classified into clade Bilateria or Radiata , respectively . <hl> As mentioned earlier , the cnidarians and ctenophores are animal phyla with true radial symmetry . All other Eumetazoa are members of the Bilateria clade . The bilaterally symmetrical animals are further divided into deuterostomes ( including chordates and echinoderms ) and two distinct clades of protostomes ( including ecdysozoans and lophotrochozoans ) ( Figure 27.13 ab ) . Ecdysozoa includes nematodes and arthropods ; they are so named for a commonly found characteristic among the group : exoskeletal molting ( termed ecdysis ) . Lophotrochozoa is named for two structural features , each common to certain phyla within the clade . Some lophotrochozoan phyla are characterized by a larval stage called trochophore larvae , and other phyla are characterized by the presence of a feeding structure called a lophophore .", "hl_sentences": "Nucleic acid and protein analyses have greatly informed the modern phylogenetic animal tree . Many evolutionary relationships in the modern tree have only recently been determined due to molecular evidence . For example , a previously classified group of animals called lophophorates , which included brachiopods and bryozoans , were long-thought to be primitive deuterostomes . This discovery allowed for the distinction of the protostome clade , the lophotrochozoans . Eumetazoa are subdivided into radially symmetrical animals and bilaterally symmetrical animals , and are thus classified into clade Bilateria or Radiata , respectively .", "question": { "cloze_format": "Consulting the modern phylogenetic tree of animals, ___ would not constitute a clade.", "normal_format": "Consulting the modern phylogenetic tree of animals, which of the following would not constitute a clade?", "question_choices": [ "deuterostomes", "lophotrochozoans", "Parazoa", "Bilateria" ], "question_id": "fs-idp241355968", "question_text": "Consulting the modern phylogenetic tree of animals, which of the following would not constitute a clade?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 1, "ans_text": "protist cells" }, "bloom": "3", "hl_context": "<hl> The current understanding of evolutionary relationships between animal , or Metazoa , phyla begins with the distinction between “ true ” animals with true differentiated tissues , called Eumetazoa , and animal phyla that do not have true differentiated tissues ( such as the sponges ) , called Parazoa . <hl> <hl> Both Parazoa and Eumetazoa evolved from a common ancestral organism that resembles the modern-day protists called choanoflagellates . <hl> <hl> These protist cells strongly resemble the sponge choanocyte cells today ( Figure 27.12 ) . <hl>", "hl_sentences": "The current understanding of evolutionary relationships between animal , or Metazoa , phyla begins with the distinction between “ true ” animals with true differentiated tissues , called Eumetazoa , and animal phyla that do not have true differentiated tissues ( such as the sponges ) , called Parazoa . Both Parazoa and Eumetazoa evolved from a common ancestral organism that resembles the modern-day protists called choanoflagellates . These protist cells strongly resemble the sponge choanocyte cells today ( Figure 27.12 ) .", "question": { "cloze_format": "___ are thought to be the most closely related to the common animal ancestor.", "normal_format": "Which of the following is thought to be the most closely related to the common animal ancestor?", "question_choices": [ "fungal cells", "protist cells", "plant cells", "bacterial cells" ], "question_id": "fs-idp62616112", "question_text": "Which of the following is thought to be the most closely related to the common animal ancestor?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 3, "ans_text": "Cryogenian period" }, "bloom": "2", "hl_context": "Fossils believed to represent the oldest animals with hard body parts were recently discovered in South Australia . These sponge-like fossils , named Coronacollina acula , date back as far as 560 million years , and are believed to show the existence of hard body parts and spicules that extended 20 – 40 cm from the main body ( estimated about 5 cm long ) . Other fossils from the Ediacaran period are shown in Figure 27.15 ab . <hl> Another recent fossil discovery may represent the earliest animal species ever found . <hl> While the validity of this claim is still under investigation , these primitive fossils appear to be small , one-centimeter long , sponge-like creatures . <hl> These fossils from South Australia date back 650 million years , actually placing the putative animal before the great ice age extinction event that marked the transition between the Cryogenian period and the Ediacaran period . <hl> Until this discovery , most scientists believed that there was no animal life prior to the Ediacaran period . <hl> Many scientists now believe that animals may in fact have evolved during the Cryogenian period . <hl>", "hl_sentences": "Another recent fossil discovery may represent the earliest animal species ever found . These fossils from South Australia date back 650 million years , actually placing the putative animal before the great ice age extinction event that marked the transition between the Cryogenian period and the Ediacaran period . Many scientists now believe that animals may in fact have evolved during the Cryogenian period .", "question": { "cloze_format": "The period that is the earliest during which animals may have appeared is the ___.", "normal_format": "Which of the following periods is the earliest during which animals may have appeared?", "question_choices": [ "Ordovician period", "Cambrian period", "Ediacaran period", "Cryogenian period" ], "question_id": "fs-idm244841072", "question_text": "Which of the following periods is the earliest during which animals may have appeared?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 1, "ans_text": "fossil data" }, "bloom": "2", "hl_context": "<hl> Natural history museums contain the fossil casts of extinct animals and information about how these animals evolved , lived , and died . <hl> Paleontogists are scientists who study prehistoric life . <hl> They use fossils to observe and explain how life evolved on Earth and how species interacted with each other and with the environment . <hl> A paleontologist needs to be knowledgeable in biology , ecology , chemistry , geology , and many other scientific disciplines . A paleontologist ’ s work may involve field studies : searching for and studying fossils . In addition to digging for and finding fossils , paleontologists also prepare fossils for further study and analysis . Although dinosaurs are probably the first animals that come to mind when thinking about paleontology , paleontologists study everything from plant life , fungi , and fish to sea animals and birds .", "hl_sentences": "Natural history museums contain the fossil casts of extinct animals and information about how these animals evolved , lived , and died . They use fossils to observe and explain how life evolved on Earth and how species interacted with each other and with the environment .", "question": { "cloze_format": "___ are a type of data that are primarily used to determine the existence and appearance of early animal species.", "normal_format": "What type of data is primarily used to determine the existence and appearance of early animal species?", "question_choices": [ "molecular data", "fossil data", "morphological data", "embryological development data" ], "question_id": "fs-idm255921760", "question_text": "What type of data is primarily used to determine the existence and appearance of early animal species?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 0, "ans_text": "Cambrian period" }, "bloom": "2", "hl_context": "<hl> The Cambrian Explosion of Animal Life The Cambrian period , occurring between approximately 542 – 488 million years ago , marks the most rapid evolution of new animal phyla and animal diversity in Earth ’ s history . <hl> It is believed that most of the animal phyla in existence today had their origins during this time , often referred to as the Cambrian explosion ( Figure 27.16 ) . Echinoderms , mollusks , worms , arthropods , and chordates arose during this period . One of the most dominant species during the Cambrian period was the trilobite , an arthropod that was among the first animals to exhibit a sense of vision ( Figure 27.17 abcd ) . The cause of the Cambrian explosion is still debated . There are many theories that attempt to answer this question . Environmental changes may have created a more suitable environment for animal life . Examples of these changes include rising atmospheric oxygen levels and large increases in oceanic calcium concentrations that preceded the Cambrian period ( Figure 27.18 ) . Some scientists believe that an expansive , continental shelf with numerous shallow lagoons or pools provided the necessary living space for larger numbers of different types of animals to co-exist . There is also support for theories that argue that ecological relationships between species , such as changes in the food web , competition for food and space , and predator-prey relationships , were primed to promote a sudden massive coevolution of species . Yet other theories claim genetic and developmental reasons for the Cambrian explosion . The morphological flexibility and complexity of animal development afforded by the evolution of Hox control genes may have provided the necessary opportunities for increases in possible animal morphologies at the time of the Cambrian period . Theories that attempt to explain why the Cambrian explosion happened must be able to provide valid reasons for the massive animal diversification , as well as explain why it happened when it did . There is evidence that both supports and refutes each of the theories described above , and the answer may very well be a combination of these and other theories .", "hl_sentences": "The Cambrian Explosion of Animal Life The Cambrian period , occurring between approximately 542 – 488 million years ago , marks the most rapid evolution of new animal phyla and animal diversity in Earth ’ s history .", "question": { "cloze_format": "The time between 542–488 million years ago marks the ___.", "normal_format": "The time between 542–488 million years ago marks which period?", "question_choices": [ "Cambrian period", "Silurian period", "Ediacaran period", "Devonian period" ], "question_id": "fs-idm102719984", "question_text": "The time between 542–488 million years ago marks which period?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 2, "ans_text": "small and soft-bodied" }, "bloom": null, "hl_context": "<hl> The time before the Cambrian period is known as the Ediacaran period ( from about 635 million years ago to 543 million years ago ) , the final period of the late Proterozoic Neoproterozoic Era ( Figure 27.14 ) . <hl> It is believed that early animal life , termed Ediacaran biota , evolved from protists at this time . Some protist species called choanoflagellates closely resemble the choanocyte cells in the simplest animals , sponges . In addition to their morphological similarity , molecular analyses have revealed similar sequence homologies in their DNA . <hl> The earliest life comprising Ediacaran biota was long believed to include only tiny , sessile , soft-bodied sea creatures . <hl> However , recently there has been increasing scientific evidence suggesting that more varied and complex animal species lived during this time , and possibly even before the Ediacaran period .", "hl_sentences": "The time before the Cambrian period is known as the Ediacaran period ( from about 635 million years ago to 543 million years ago ) , the final period of the late Proterozoic Neoproterozoic Era ( Figure 27.14 ) . The earliest life comprising Ediacaran biota was long believed to include only tiny , sessile , soft-bodied sea creatures .", "question": { "cloze_format": "Until recent discoveries suggested otherwise, animals existing before the Cambrian period were believed to be ___.", "normal_format": "What did animals exist before the Cambrian period believed to be until recent discoveries?", "question_choices": [ "small and ocean-dwelling", "small and non-motile", "small and soft-bodied", "small and radially symmetrical or asymmetrical" ], "question_id": "fs-idm115106224", "question_text": "Until recent discoveries suggested otherwise, animals existing before the Cambrian period were believed to be:" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 1, "ans_text": "Ordovician period" }, "bloom": null, "hl_context": "Post-Cambrian Evolution and Mass Extinctions The periods that followed the Cambrian during the Paleozoic Era are marked by further animal evolution and the emergence of many new orders , families , and species . As animal phyla continued to diversify , new species adapted to new ecological niches . <hl> During the Ordovician period , which followed the Cambrian period , plant life first appeared on land . <hl> This change allowed formerly aquatic animal species to invade land , feeding directly on plants or decaying vegetation . Continual changes in temperature and moisture throughout the remainder of the Paleozoic Era due to continental plate movements encouraged the development of new adaptations to terrestrial existence in animals , such as limbed appendages in amphibians and epidermal scales in reptiles .", "hl_sentences": "During the Ordovician period , which followed the Cambrian period , plant life first appeared on land .", "question": { "cloze_format": "The period during which plant life first appeared on land is called the ___ .", "normal_format": "Plant life first appeared on land during which of the following periods?", "question_choices": [ "Cambrian period", "Ordovician period", "Silurian period", "Devonian period" ], "question_id": "fs-idm158540544", "question_text": "Plant life first appeared on land during which of the following periods?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 3, "ans_text": "more than 5" }, "bloom": "3", "hl_context": "<hl> Another mass extinction event occurred at the end of the Cretaceous period , bringing the Mesozoic Era to an end . <hl> Skies darkened and temperatures fell as a large meteor impact and tons of volcanic ash blocked incoming sunlight . Plants died , herbivores and carnivores starved , and the mostly cold-blooded dinosaurs ceded their dominance of the landscape to more warm-blooded mammals . In the following Cenozoic Era , mammals radiated into terrestrial and aquatic niches once occupied by dinosaurs , and birds , the warm-blooded offshoots of one line of the ruling reptiles , became aerial specialists . The appearance and dominance of flowering plants in the Cenozoic Era created new niches for insects , as well as for birds and mammals . Changes in animal species diversity during the late Cretaceous and early Cenozoic were also promoted by a dramatic shift in Earth ’ s geography , as continental plates slid over the crust into their current positions , leaving some animal groups isolated on islands and continents , or separated by mountain ranges or inland seas from other competitors . Early in the Cenozoic , new ecosystems appeared , with the evolution of grasses and coral reefs . <hl> Late in the Cenozoic , further extinctions followed by speciation occurred during ice ages that covered high latitudes with ice and then retreated , leaving new open spaces for colonization . <hl> Changes in the environment often create new niches ( living spaces ) that contribute to rapid speciation and increased diversity . On the other hand , cataclysmic events , such as volcanic eruptions and meteor strikes that obliterate life , can result in devastating losses of diversity . <hl> Such periods of mass extinction ( Figure 27.19 ) have occurred repeatedly in the evolutionary record of life , erasing some genetic lines while creating room for others to evolve into the empty niches left behind . <hl> <hl> The end of the Permian period ( and the Paleozoic Era ) was marked by the largest mass extinction event in Earth ’ s history , a loss of roughly 95 percent of the extant species at that time . <hl> Some of the dominant phyla in the world ’ s oceans , such as the trilobites , disappeared completely . On land , the disappearance of some dominant species of Permian reptiles made it possible for a new line of reptiles to emerge , the dinosaurs . The warm and stable climatic conditions of the ensuing Mesozoic Era promoted an explosive diversification of dinosaurs into every conceivable niche in land , air , and water . Plants , too , radiated into new landscapes and empty niches , creating complex communities of producers and consumers , some of which became very large on the abundant food available .", "hl_sentences": "Another mass extinction event occurred at the end of the Cretaceous period , bringing the Mesozoic Era to an end . Late in the Cenozoic , further extinctions followed by speciation occurred during ice ages that covered high latitudes with ice and then retreated , leaving new open spaces for colonization . Such periods of mass extinction ( Figure 27.19 ) have occurred repeatedly in the evolutionary record of life , erasing some genetic lines while creating room for others to evolve into the empty niches left behind . The end of the Permian period ( and the Paleozoic Era ) was marked by the largest mass extinction event in Earth ’ s history , a loss of roughly 95 percent of the extant species at that time .", "question": { "cloze_format": "The amount of mass extinction events that occurred throughout the evolutionary history of animals is approximately ___.", "normal_format": "Approximately how many mass extinction events occurred throughout the evolutionary history of animals?", "question_choices": [ "3", "4", "5", "more than 5" ], "question_id": "fs-idm231350784", "question_text": "Approximately how many mass extinction events occurred throughout the evolutionary history of animals?" }, "references_are_paraphrase": null } ]
27
27.1 Features of the Animal Kingdom Learning Objectives By the end of this section, you will be able to: List the features that distinguish the kingdom Animalia from other kingdoms Explain the processes of animal reproduction and embryonic development Describe the roles that Hox genes play in development Even though members of the animal kingdom are incredibly diverse, most animals share certain features that distinguish them from organisms in other kingdoms. All animals are eukaryotic, multicellular organisms, and almost all animals have a complex tissue structure with differentiated and specialized tissues. Most animals are motile, at least during certain life stages. All animals require a source of food and are therefore heterotrophic, ingesting other living or dead organisms; this feature distinguishes them from autotrophic organisms, such as most plants, which synthesize their own nutrients through photosynthesis. As heterotrophs, animals may be carnivores, herbivores, omnivores, or parasites ( Figure 27.2 ab ). Most animals reproduce sexually, and the offspring pass through a series of developmental stages that establish a determined and fixed body plan. The body plan refers to the morphology of an animal, determined by developmental cues. Complex Tissue Structure As multicellular organisms, animals differ from plants and fungi because their cells don’t have cell walls, their cells may be embedded in an extracellular matrix (such as bone, skin, or connective tissue), and their cells have unique structures for intercellular communication (such as gap junctions). In addition, animals possess unique tissues, absent in fungi and plants, which allow coordination (nerve tissue) of motility (muscle tissue). Animals are also characterized by specialized connective tissues that provide structural support for cells and organs. This connective tissue constitutes the extracellular surroundings of cells and is made up of organic and inorganic materials. In vertebrates, bone tissue is a type of connective tissue that supports the entire body structure. The complex bodies and activities of vertebrates demand such supportive tissues. Epithelial tissues cover, line, protect, and secrete. Epithelial tissues include the epidermis of the integument, the lining of the digestive tract and trachea, and make up the ducts of the liver and glands of advanced animals. The animal kingdom is divided into Parazoa (sponges) and Eumetazoa (all other animals). As very simple animals, the organisms in group Parazoa (“beside animal”) do not contain true specialized tissues; although they do possess specialized cells that perform different functions, those cells are not organized into tissues. These organisms are considered animals since they lack the ability to make their own food. Animals with true tissues are in the group Eumetazoa (“true animals”). When we think of animals, we usually think of Eumetazoans, since most animals fall into this category. The different types of tissues in true animals are responsible for carrying out specific functions for the organism. This differentiation and specialization of tissues is part of what allows for such incredible animal diversity. For example, the evolution of nerve tissues and muscle tissues has resulted in animals’ unique ability to rapidly sense and respond to changes in their environment. This allows animals to survive in environments where they must compete with other species to meet their nutritional demands. Link to Learning Watch a presentation by biologist E.O. Wilson on the importance of diversity. Animal Reproduction and Development Most animals are diploid organisms, meaning that their body (somatic) cells are diploid and haploid reproductive (gamete) cells are produced through meiosis. Some exceptions exist: For example, in bees, wasps, and ants, the male is haploid because it develops from unfertilized eggs. Most animals undergo sexual reproduction: This fact distinguishes animals from fungi, protists, and bacteria, where asexual reproduction is common or exclusive. However, a few groups, such as cnidarians, flatworm, and roundworms, undergo asexual reproduction, although nearly all of those animals also have a sexual phase to their life cycle. Processes of Animal Reproduction and Embryonic Development During sexual reproduction, the haploid gametes of the male and female individuals of a species combine in a process called fertilization. Typically, the small, motile male sperm fertilizes the much larger, sessile female egg. This process produces a diploid fertilized egg called a zygote. Some animal species—including sea stars and sea anemones, as well as some insects, reptiles, and fish—are capable of asexual reproduction. The most common forms of asexual reproduction for stationary aquatic animals include budding and fragmentation, where part of a parent individual can separate and grow into a new individual. In contrast, a form of asexual reproduction found in certain insects and vertebrates is called parthenogenesis (or “virgin beginning”), where unfertilized eggs can develop into new male offspring. This type of parthenogenesis is called haplodiploidy. These types of asexual reproduction produce genetically identical offspring, which is disadvantageous from the perspective of evolutionary adaptability because of the potential buildup of deleterious mutations. However, for animals that are limited in their capacity to attract mates, asexual reproduction can ensure genetic propagation. After fertilization, a series of developmental stages occur during which primary germ layers are established and reorganize to form an embryo. During this process, animal tissues begin to specialize and organize into organs and organ systems, determining their future morphology and physiology. Some animals, such as grasshoppers, undergo incomplete metamorphosis, in which the young resemble the adult. Other animals, such as some insects, undergo complete metamorphosis where individuals enter one or more larval stages that may in differ in structure and function from the adult ( Figure 27.3 ). For the latter, the young and the adult may have different diets, limiting competition for food between them. Regardless of whether a species undergoes complete or incomplete metamorphosis, the series of developmental stages of the embryo remains largely the same for most members of the animal kingdom. The process of animal development begins with the cleavage , or series of mitotic cell divisions, of the zygote ( Figure 27.4 ). Three cell divisions transform the single-celled zygote into an eight-celled structure. After further cell division and rearrangement of existing cells, a 6–32-celled hollow structure called a blastula is formed. Next, the blastula undergoes further cell division and cellular rearrangement during a process called gastrulation. This leads to the formation of the next developmental stage, the gastrula , in which the future digestive cavity is formed. Different cell layers (called germ layers ) are formed during gastrulation. These germ layers are programmed to develop into certain tissue types, organs, and organ systems during a process called organogenesis . Link to Learning Watch the following video to see how human embryonic development (after the blastula and gastrula stages of development) reflects evolution. The Role of Homeobox ( Hox ) Genes in Animal Development Since the early 19 th century, scientists have observed that many animals, from the very simple to the complex, shared similar embryonic morphology and development. Surprisingly, a human embryo and a frog embryo, at a certain stage of embryonic development, look remarkably alike. For a long time, scientists did not understand why so many animal species looked similar during embryonic development but were very different as adults. They wondered what dictated the developmental direction that a fly, mouse, frog, or human embryo would take. Near the end of the 20 th century, a particular class of genes was discovered that had this very job. These genes that determine animal structure are called “homeotic genes,” and they contain DNA sequences called homeoboxes. The animal genes containing homeobox sequences are specifically referred to as Hox genes . This family of genes is responsible for determining the general body plan, such as the number of body segments of an animal, the number and placement of appendages, and animal head-tail directionality. The first Hox genes to be sequenced were those from the fruit fly ( Drosophila melanogaster ). A single Hox mutation in the fruit fly can result in an extra pair of wings or even appendages growing from the “wrong” body part. While there are a great many genes that play roles in the morphological development of an animal, what makes Hox genes so powerful is that they serve as master control genes that can turn on or off large numbers of other genes. Hox genes do this by coding transcription factors that control the expression of numerous other genes. Hox genes are homologous in the animal kingdom, that is, the genetic sequences of Hox genes and their positions on chromosomes are remarkably similar across most animals because of their presence in a common ancestor, from worms to flies, mice, and humans ( Figure 27.5 ). One of the contributions to increased animal body complexity is that Hox genes have undergone at least two duplication events during animal evolution, with the additional genes allowing for more complex body types to evolve. Visual Connection If a Hox 13 gene in a mouse was replaced with a Hox 1 gene, how might this alter animal development? 27.2 Features Used to Classify Animals Learning Objectives By the end of this section, you will be able to: Explain the differences in animal body plans that support basic animal classification Compare and contrast the embryonic development of protostomes and deuterostomes Scientists have developed a classification scheme that categorizes all members of the animal kingdom, although there are exceptions to most “rules” governing animal classification ( Figure 27.6 ). Animals are primarily classified according to morphological and developmental characteristics, such as a body plan. One of the most prominent features of the body plan of true animals is that they are morphologically symmetrical. This means that their distribution of body parts is balanced along an axis. Additional characteristics include the number of tissue layers formed during development, the presence or absence of an internal body cavity, and other features of embryological development, such as the origin of the mouth and anus. Visual Connection Which of the following statements is false? Eumetazoans have specialized tissues and parazoans don’t. Lophotrochozoa and Ecdysozoa are both Bilataria. Acoela and Cnidaria both possess radial symmetry. Arthropods are more closely related to nematodes than they are to annelids. Animal Characterization Based on Body Symmetry At a very basic level of classification, true animals can be largely divided into three groups based on the type of symmetry of their body plan: radially symmetrical, bilaterally symmetrical, and asymmetrical. Asymmetry is a unique feature of Parazoa ( Figure 27.7 a ). Only a few animal groups display radial symmetry. All types of symmetry are well suited to meet the unique demands of a particular animal’s lifestyle. Radial symmetry is the arrangement of body parts around a central axis, as is seen in a drinking glass or pie. It results in animals having top and bottom surfaces but no left and right sides, or front or back. The two halves of a radially symmetrical animal may be described as the side with a mouth or “oral side,” and the side without a mouth (the “aboral side”). This form of symmetry marks the body plans of animals in the phyla Ctenophora and Cnidaria, including jellyfish and adult sea anemones ( Figure 27.7 bc ). Radial symmetry equips these sea creatures (which may be sedentary or only capable of slow movement or floating) to experience the environment equally from all directions. Bilateral symmetry involves the division of the animal through a sagittal plane, resulting in two mirror image, right and left halves, such as those of a butterfly ( Figure 27.7 d ), crab, or human body. Animals with bilateral symmetry have a “head” and “tail” (anterior vs. posterior), front and back (dorsal vs. ventral), and right and left sides ( Figure 27.8 ). All true animals except those with radial symmetry are bilaterally symmetrical. The evolution of bilateral symmetry that allowed for the formation of anterior and posterior (head and tail) ends promoted a phenomenon called cephalization, which refers to the collection of an organized nervous system at the animal’s anterior end. In contrast to radial symmetry, which is best suited for stationary or limited-motion lifestyles, bilateral symmetry allows for streamlined and directional motion. In evolutionary terms, this simple form of symmetry promoted active mobility and increased sophistication of resource-seeking and predator-prey relationships. Animals in the phylum Echinodermata (such as sea stars, sand dollars, and sea urchins) display radial symmetry as adults, but their larval stages exhibit bilateral symmetry. This is termed secondary radial symmetry. They are believed to have evolved from bilaterally symmetrical animals; thus, they are classified as bilaterally symmetrical. Link to Learning Watch this video to see a quick sketch of the different types of body symmetry. Click to view content Animal Characterization Based on Features of Embryological Development Most animal species undergo a separation of tissues into germ layers during embryonic development. Recall that these germ layers are formed during gastrulation, and that they are predetermined to develop into the animal’s specialized tissues and organs. Animals develop either two or three embryonic germs layers ( Figure 27.9 ). The animals that display radial symmetry develop two germ layers, an inner layer (endoderm) and an outer layer (ectoderm). These animals are called diploblasts . Diploblasts have a non-living layer between the endoderm and ectoderm. More complex animals (those with bilateral symmetry) develop three tissue layers: an inner layer (endoderm), an outer layer (ectoderm), and a middle layer (mesoderm). Animals with three tissue layers are called triploblasts . Visual Connection Which of the following statements about diploblasts and triploblasts is false? Animals that display radial symmetry are diploblasts. Animals that display bilateral symmetry are triploblasts. The endoderm gives rise to the lining of the digestive tract and the respiratory tract. The mesoderm gives rise to the central nervous system. Each of the three germ layers is programmed to give rise to particular body tissues and organs. The endoderm gives rise to the lining of the digestive tract (including the stomach, intestines, liver, and pancreas), as well as to the lining of the trachea, bronchi, and lungs of the respiratory tract, along with a few other structures. The ectoderm develops into the outer epithelial covering of the body surface, the central nervous system, and a few other structures. The mesoderm is the third germ layer; it forms between the endoderm and ectoderm in triploblasts. This germ layer gives rise to all muscle tissues (including the cardiac tissues and muscles of the intestines), connective tissues such as the skeleton and blood cells, and most other visceral organs such as the kidneys and the spleen. Presence or Absence of a Coelom Further subdivision of animals with three germ layers (triploblasts) results in the separation of animals that may develop an internal body cavity derived from mesoderm, called a coelom , and those that do not. This epithelial cell-lined coelomic cavity represents a space, usually filled with fluid, which lies between the visceral organs and the body wall. It houses many organs such as the digestive system, kidneys, reproductive organs, and heart, and contains the circulatory system. In some animals, such as mammals, the part of the coelom called the pleural cavity provides space for the lungs to expand during breathing. The evolution of the coelom is associated with many functional advantages. Primarily, the coelom provides cushioning and shock absorption for the major organ systems. Organs housed within the coelom can grow and move freely, which promotes optimal organ development and placement. The coelom also provides space for the diffusion of gases and nutrients, as well as body flexibility, promoting improved animal motility. Triploblasts that do not develop a coelom are called acoelomates , and their mesoderm region is completely filled with tissue, although they do still have a gut cavity. Examples of acoelomates include animals in the phylum Platyhelminthes, also known as flatworms. Animals with a true coelom are called eucoelomates (or coelomates) ( Figure 27.10 ). A true coelom arises entirely within the mesoderm germ layer and is lined by an epithelial membrane. This membrane also lines the organs within the coelom, connecting and holding them in position while allowing them some free motion. Annelids, mollusks, arthropods, echinoderms, and chordates are all eucoelomates. A third group of triploblasts has a slightly different coelom derived partly from mesoderm and partly from endoderm, which is found between the two layers. Although still functional, these are considered false coeloms, and those animals are called pseudocoelomates . The phylum Nematoda (roundworms) is an example of a pseudocoelomate. True coelomates can be further characterized based on certain features of their early embryological development. Embryonic Development of the Mouth Bilaterally symmetrical, triploblastic eucoelomates can be further divided into two groups based on differences in their early embryonic development. Protostomes include arthropods, mollusks, and annelids. Deuterostomes include more complex animals such as chordates but also some simple animals such as echinoderms. These two groups are separated based on which opening of the digestive cavity develops first: mouth or anus. The word protostome comes from the Greek word meaning “mouth first,” and deuterostome originates from the word meaning “mouth second” (in this case, the anus develops first). The mouth or anus develops from a structure called the blastopore ( Figure 27.11 ). The blastopore is the indentation formed during the initial stages of gastrulation. In later stages, a second opening forms, and these two openings will eventually give rise to the mouth and anus ( Figure 27.11 ). It has long been believed that the blastopore develops into the mouth of protostomes, with the second opening developing into the anus; the opposite is true for deuterostomes. Recent evidence has challenged this view of the development of the blastopore of protostomes, however, and the theory remains under debate. Another distinction between protostomes and deuterostomes is the method of coelom formation, beginning from the gastrula stage. The coelom of most protostomes is formed through a process called schizocoely , meaning that during development, a solid mass of the mesoderm splits apart and forms the hollow opening of the coelom. Deuterostomes differ in that their coelom forms through a process called enterocoely . Here, the mesoderm develops as pouches that are pinched off from the endoderm tissue. These pouches eventually fuse to form the mesoderm, which then gives rise to the coelom. The earliest distinction between protostomes and deuterostomes is the type of cleavage undergone by the zygote. Protostomes undergo spiral cleavage , meaning that the cells of one pole of the embryo are rotated, and thus misaligned, with respect to the cells of the opposite pole. This is due to the oblique angle of the cleavage. Deuterostomes undergo radial cleavage , where the cleavage axes are either parallel or perpendicular to the polar axis, resulting in the alignment of the cells between the two poles. There is a second distinction between the types of cleavage in protostomes and deuterostomes. In addition to spiral cleavage, protostomes also undergo determinate cleavage . This means that even at this early stage, the developmental fate of each embryonic cell is already determined. A cell does not have the ability to develop into any cell type. In contrast, deuterostomes undergo indeterminate cleavage , in which cells are not yet pre-determined at this early stage to develop into specific cell types. These cells are referred to as undifferentiated cells. This characteristic of deuterostomes is reflected in the existence of familiar embryonic stem cells, which have the ability to develop into any cell type until their fate is programmed at a later developmental stage. Evolution Connection The Evolution of the Coelom One of the first steps in the classification of animals is to examine the animal’s body. Studying the body parts tells us not only the roles of the organs in question but also how the species may have evolved. One such structure that is used in classification of animals is the coelom. A coelom is a body cavity that forms during early embryonic development. The coelom allows for compartmentalization of the body parts, so that different organ systems can evolve and nutrient transport is possible. Additionally, because the coelom is a fluid-filled cavity, it protects the organs from shock and compression. Simple animals, such as worms and jellyfish, do not have a coelom. All vertebrates have a coelom that helped them evolve complex organ systems. Animals that do not have a coelom are called acoelomates. Flatworms and tapeworms are examples of acoelomates. They rely on passive diffusion for nutrient transport across their body. Additionally, the internal organs of acoelomates are not protected from crushing. Animals that have a true coelom are called eucoelomates; all vertebrates are eucoelomates. The coelom evolves from the mesoderm during embryogenesis. The abdominal cavity contains the stomach, liver, gall bladder, and other digestive organs. Another category of invertebrates animals based on body cavity is pseudocoelomates. These animals have a pseudo-cavity that is not completely lined by mesoderm. Examples include nematode parasites and small worms. These animals are thought to have evolved from coelomates and may have lost their ability to form a coelom through genetic mutations. Thus, this step in early embryogenesis—the formation of the coelom—has had a large evolutionary impact on the various species of the animal kingdom. 27.3 Animal Phylogeny Learning Objectives By the end of this section, you will be able to: Interpret the metazoan phylogenetic tree Describe the types of data that scientists use to construct and revise animal phylogeny List some of the relationships within the modern phylogenetic tree that have been discovered as a result of modern molecular data Biologists strive to understand the evolutionary history and relationships of members of the animal kingdom, and all of life, for that matter. The study of phylogeny aims to determine the evolutionary relationships between phyla. Currently, most biologists divide the animal kingdom into 35 to 40 phyla. Scientists develop phylogenetic trees, which serve as hypotheses about which species have evolved from which ancestors Recall that until recently, only morphological characteristics and the fossil record were used to determine phylogenetic relationships among animals. Scientific understanding of the distinctions and hierarchies between anatomical characteristics provided much of this knowledge. Used alone, however, this information can be misleading. Morphological characteristics may evolve multiple times, and independently, through evolutionary history. Analogous characteristics may appear similar between animals, but their underlying evolution may be very different. With the advancement of molecular technologies, modern phylogenetics is now informed by genetic and molecular analyses, in addition to traditional morphological and fossil data. With a growing understanding of genetics, the animal evolutionary tree has changed substantially and continues to change as new DNA and RNA analyses are performed on additional animal species. Constructing an Animal Phylogenetic Tree The current understanding of evolutionary relationships between animal, or Metazoa , phyla begins with the distinction between “true” animals with true differentiated tissues, called Eumetazoa , and animal phyla that do not have true differentiated tissues (such as the sponges), called Parazoa . Both Parazoa and Eumetazoa evolved from a common ancestral organism that resembles the modern-day protists called choanoflagellates. These protist cells strongly resemble the sponge choanocyte cells today ( Figure 27.12 ). Eumetazoa are subdivided into radially symmetrical animals and bilaterally symmetrical animals, and are thus classified into clade Bilateria or Radiata, respectively. As mentioned earlier, the cnidarians and ctenophores are animal phyla with true radial symmetry. All other Eumetazoa are members of the Bilateria clade. The bilaterally symmetrical animals are further divided into deuterostomes (including chordates and echinoderms) and two distinct clades of protostomes (including ecdysozoans and lophotrochozoans) ( Figure 27.13 ab). Ecdysozoa includes nematodes and arthropods; they are so named for a commonly found characteristic among the group: exoskeletal molting (termed ecdysis). Lophotrochozoa is named for two structural features, each common to certain phyla within the clade. Some lophotrochozoan phyla are characterized by a larval stage called trochophore larvae, and other phyla are characterized by the presence of a feeding structure called a lophophore. Link to Learning Explore an interactive tree of life here. Zoom and click to learn more about the organisms and their evolutionary relationships. Modern Advances in Phylogenetic Understanding Come from Molecular Analyses The phylogenetic groupings are continually being debated and refined by evolutionary biologists. Each year, new evidence emerges that further alters the relationships described by a phylogenetic tree diagram. Link to Learning Watch the following video to learn how biologists use genetic data to determine relationships among organisms. Nucleic acid and protein analyses have greatly informed the modern phylogenetic animal tree. These data come from a variety of molecular sources, such as mitochondrial DNA, nuclear DNA, ribosomal RNA (rRNA), and certain cellular proteins. Many evolutionary relationships in the modern tree have only recently been determined due to molecular evidence. For example, a previously classified group of animals called lophophorates, which included brachiopods and bryozoans, were long-thought to be primitive deuterostomes. Extensive molecular analysis using rRNA data found these animals to be protostomes, more closely related to annelids and mollusks. This discovery allowed for the distinction of the protostome clade, the lophotrochozoans. Molecular data have also shed light on some differences within the lophotrochozoan group, and some scientists believe that the phyla Platyhelminthes and Rotifera within this group should actually belong to their own group of protostomes termed Platyzoa. Molecular research similar to the discoveries that brought about the distinction of the lophotrochozoan clade has also revealed a dramatic rearrangement of the relationships between mollusks, annelids, arthropods, and nematodes, and a new ecdysozoan clade was formed. Due to morphological similarities in their segmented body types, annelids and arthropods were once thought to be closely related. However, molecular evidence has revealed that arthropods are actually more closely related to nematodes, now comprising the ecdysozoan clade, and annelids are more closely related to mollusks, brachiopods, and other phyla in the lophotrochozoan clade. These two clades now make up the protostomes. Another change to former phylogenetic groupings because of molecular analyses includes the emergence of an entirely new phylum of worm called Acoelomorpha. These acoel flatworms were long thought to belong to the phylum Platyhelminthes because of their similar “flatworm” morphology. However, molecular analyses revealed this to be a false relationship and originally suggested that acoels represented living species of some of the earliest divergent bilaterians. More recent research into the acoelomorphs has called this hypothesis into question and suggested a closer relationship with deuterostomes. The placement of this new phylum remains disputed, but scientists agree that with sufficient molecular data, their true phylogeny will be determined. 27.4 The Evolutionary History of the Animal Kingdom Learning Objectives By the end of this section, you will be able to: Describe the features that characterized the earliest animals and when they appeared on earth Explain the significance of the Cambrian period for animal evolution and the changes in animal diversity that took place during that time Describe some of the unresolved questions surrounding the Cambrian explosion Discuss the implications of mass animal extinctions that have occurred in evolutionary history Many questions regarding the origins and evolutionary history of the animal kingdom continue to be researched and debated, as new fossil and molecular evidence change prevailing theories. Some of these questions include the following: How long have animals existed on Earth? What were the earliest members of the animal kingdom, and what organism was their common ancestor? While animal diversity increased during the Cambrian period of the Paleozoic era, 530 million years ago, modern fossil evidence suggests that primitive animal species existed much earlier. Pre-Cambrian Animal Life The time before the Cambrian period is known as the Ediacaran period (from about 635 million years ago to 543 million years ago), the final period of the late Proterozoic Neoproterozoic Era ( Figure 27.14 ). It is believed that early animal life, termed Ediacaran biota, evolved from protists at this time. Some protist species called choanoflagellates closely resemble the choanocyte cells in the simplest animals, sponges. In addition to their morphological similarity, molecular analyses have revealed similar sequence homologies in their DNA. The earliest life comprising Ediacaran biota was long believed to include only tiny, sessile, soft-bodied sea creatures. However, recently there has been increasing scientific evidence suggesting that more varied and complex animal species lived during this time, and possibly even before the Ediacaran period. Fossils believed to represent the oldest animals with hard body parts were recently discovered in South Australia. These sponge-like fossils, named Coronacollina acula , date back as far as 560 million years, and are believed to show the existence of hard body parts and spicules that extended 20–40 cm from the main body (estimated about 5 cm long). Other fossils from the Ediacaran period are shown in Figure 27.15 ab . Another recent fossil discovery may represent the earliest animal species ever found. While the validity of this claim is still under investigation, these primitive fossils appear to be small, one-centimeter long, sponge-like creatures. These fossils from South Australia date back 650 million years, actually placing the putative animal before the great ice age extinction event that marked the transition between the Cryogenian period and the Ediacaran period. Until this discovery, most scientists believed that there was no animal life prior to the Ediacaran period. Many scientists now believe that animals may in fact have evolved during the Cryogenian period. The Cambrian Explosion of Animal Life The Cambrian period, occurring between approximately 542–488 million years ago, marks the most rapid evolution of new animal phyla and animal diversity in Earth’s history. It is believed that most of the animal phyla in existence today had their origins during this time, often referred to as the Cambrian explosion ( Figure 27.16 ). Echinoderms, mollusks, worms, arthropods, and chordates arose during this period. One of the most dominant species during the Cambrian period was the trilobite, an arthropod that was among the first animals to exhibit a sense of vision ( Figure 27.17 abcd ). The cause of the Cambrian explosion is still debated. There are many theories that attempt to answer this question. Environmental changes may have created a more suitable environment for animal life. Examples of these changes include rising atmospheric oxygen levels and large increases in oceanic calcium concentrations that preceded the Cambrian period ( Figure 27.18 ). Some scientists believe that an expansive, continental shelf with numerous shallow lagoons or pools provided the necessary living space for larger numbers of different types of animals to co-exist. There is also support for theories that argue that ecological relationships between species, such as changes in the food web, competition for food and space, and predator-prey relationships, were primed to promote a sudden massive coevolution of species. Yet other theories claim genetic and developmental reasons for the Cambrian explosion. The morphological flexibility and complexity of animal development afforded by the evolution of Hox control genes may have provided the necessary opportunities for increases in possible animal morphologies at the time of the Cambrian period. Theories that attempt to explain why the Cambrian explosion happened must be able to provide valid reasons for the massive animal diversification, as well as explain why it happened when it did. There is evidence that both supports and refutes each of the theories described above, and the answer may very well be a combination of these and other theories. However, unresolved questions about the animal diversification that took place during the Cambrian period remain. For example, we do not understand how the evolution of so many species occurred in such a short period of time. Was there really an “explosion” of life at this particular time? Some scientists question the validity of the this idea, because there is increasing evidence to suggest that more animal life existed prior to the Cambrian period and that other similar species’ so-called explosions (or radiations) occurred later in history as well. Furthermore, the vast diversification of animal species that appears to have begun during the Cambrian period continued well into the following Ordovician period. Despite some of these arguments, most scientists agree that the Cambrian period marked a time of impressively rapid animal evolution and diversification that is unmatched elsewhere during history. Link to Learning View an animation of what ocean life may have been like during the Cambrian explosion. Click to view content Post-Cambrian Evolution and Mass Extinctions The periods that followed the Cambrian during the Paleozoic Era are marked by further animal evolution and the emergence of many new orders, families, and species. As animal phyla continued to diversify, new species adapted to new ecological niches. During the Ordovician period, which followed the Cambrian period, plant life first appeared on land. This change allowed formerly aquatic animal species to invade land, feeding directly on plants or decaying vegetation. Continual changes in temperature and moisture throughout the remainder of the Paleozoic Era due to continental plate movements encouraged the development of new adaptations to terrestrial existence in animals, such as limbed appendages in amphibians and epidermal scales in reptiles. Changes in the environment often create new niches (living spaces) that contribute to rapid speciation and increased diversity. On the other hand, cataclysmic events, such as volcanic eruptions and meteor strikes that obliterate life, can result in devastating losses of diversity. Such periods of mass extinction ( Figure 27.19 ) have occurred repeatedly in the evolutionary record of life, erasing some genetic lines while creating room for others to evolve into the empty niches left behind. The end of the Permian period (and the Paleozoic Era) was marked by the largest mass extinction event in Earth’s history, a loss of roughly 95 percent of the extant species at that time. Some of the dominant phyla in the world’s oceans, such as the trilobites, disappeared completely. On land, the disappearance of some dominant species of Permian reptiles made it possible for a new line of reptiles to emerge, the dinosaurs. The warm and stable climatic conditions of the ensuing Mesozoic Era promoted an explosive diversification of dinosaurs into every conceivable niche in land, air, and water. Plants, too, radiated into new landscapes and empty niches, creating complex communities of producers and consumers, some of which became very large on the abundant food available. Another mass extinction event occurred at the end of the Cretaceous period, bringing the Mesozoic Era to an end. Skies darkened and temperatures fell as a large meteor impact and tons of volcanic ash blocked incoming sunlight. Plants died, herbivores and carnivores starved, and the mostly cold-blooded dinosaurs ceded their dominance of the landscape to more warm-blooded mammals. In the following Cenozoic Era, mammals radiated into terrestrial and aquatic niches once occupied by dinosaurs, and birds, the warm-blooded offshoots of one line of the ruling reptiles, became aerial specialists. The appearance and dominance of flowering plants in the Cenozoic Era created new niches for insects, as well as for birds and mammals. Changes in animal species diversity during the late Cretaceous and early Cenozoic were also promoted by a dramatic shift in Earth’s geography, as continental plates slid over the crust into their current positions, leaving some animal groups isolated on islands and continents, or separated by mountain ranges or inland seas from other competitors. Early in the Cenozoic, new ecosystems appeared, with the evolution of grasses and coral reefs. Late in the Cenozoic, further extinctions followed by speciation occurred during ice ages that covered high latitudes with ice and then retreated, leaving new open spaces for colonization. Link to Learning Watch the following video to learn more about the mass extinctions. Career Connection Paleontologist Natural history museums contain the fossil casts of extinct animals and information about how these animals evolved, lived, and died. Paleontogists are scientists who study prehistoric life. They use fossils to observe and explain how life evolved on Earth and how species interacted with each other and with the environment. A paleontologist needs to be knowledgeable in biology, ecology, chemistry, geology, and many other scientific disciplines. A paleontologist’s work may involve field studies: searching for and studying fossils. In addition to digging for and finding fossils, paleontologists also prepare fossils for further study and analysis. Although dinosaurs are probably the first animals that come to mind when thinking about paleontology, paleontologists study everything from plant life, fungi, and fish to sea animals and birds. An undergraduate degree in earth science or biology is a good place to start toward the career path of becoming a paleontologist. Most often, a graduate degree is necessary. Additionally, work experience in a museum or in a paleontology lab is useful.
biology
Chapter Outline 17.1 Biotechnology 17.2 Mapping Genomes 17.3 Whole-Genome Sequencing 17.4 Applying Genomics 17.5 Genomics and Proteomics Introduction The study of nucleic acids began with the discovery of DNA, progressed to the study of genes and small fragments, and has now exploded to the field of genomics. Genomics is the study of entire genomes, including the complete set of genes, their nucleotide sequence and organization, and their interactions within a species and with other species. The advances in genomics have been made possible by DNA sequencing technology. Just as information technology has led to Google maps that enable people to get detailed information about locations around the globe, genomic information is used to create similar maps of the DNA of different organisms. These findings have helped anthropologists to better understand human migration and have aided the field of medicine through the mapping of human genetic diseases. The ways in which genomic information can contribute to scientific understanding are varied and quickly growing.
[ { "answer": { "ans_choice": 1, "ans_text": "introducing recombinant DNA into an organism by any means" }, "bloom": null, "hl_context": "<hl> Genetic engineering is the alteration of an organism ’ s genotype using recombinant DNA technology to modify an organism ’ s DNA to achieve desirable traits . <hl> <hl> The addition of foreign DNA in the form of recombinant DNA vectors generated by molecular cloning is the most common method of genetic engineering . <hl> <hl> The organism that receives the recombinant DNA is called a genetically modified organism ( GMO ) . <hl> If the foreign DNA that is introduced comes from a different species , the host organism is called transgenic . Bacteria , plants , and animals have been genetically modified since the early 1970s for academic , medical , agricultural , and industrial purposes . In the US , GMOs such as Roundup-ready soybeans and borer-resistant corn are part of many common processed foods .", "hl_sentences": "Genetic engineering is the alteration of an organism ’ s genotype using recombinant DNA technology to modify an organism ’ s DNA to achieve desirable traits . The addition of foreign DNA in the form of recombinant DNA vectors generated by molecular cloning is the most common method of genetic engineering . The organism that receives the recombinant DNA is called a genetically modified organism ( GMO ) .", "question": { "cloze_format": "GMOs are created by ________.", "normal_format": "How are GMOs created?", "question_choices": [ "generating genomic DNA fragments with restriction endonucleases", "introducing recombinant DNA into an organism by any means", "overexpressing proteins in E. coli.", "all of the above" ], "question_id": "fs-id2316890", "question_text": "GMOs are created by ________." }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 2, "ans_text": "of tissues to cure inheritable disease" }, "bloom": null, "hl_context": "<hl> Gene therapy is a genetic engineering technique used to cure disease . <hl> <hl> In its simplest form , it involves the introduction of a good gene at a random location in the genome to aid the cure of a disease that is caused by a mutated gene . <hl> <hl> The good gene is usually introduced into diseased cells as part of a vector transmitted by a virus that can infect the host cell and deliver the foreign DNA ( Figure 17.9 ) . <hl> More advanced forms of gene therapy try to correct the mutation at the original site in the genome , such as is the case with treatment of severe combined immunodeficiency ( SCID ) .", "hl_sentences": "Gene therapy is a genetic engineering technique used to cure disease . In its simplest form , it involves the introduction of a good gene at a random location in the genome to aid the cure of a disease that is caused by a mutated gene . The good gene is usually introduced into diseased cells as part of a vector transmitted by a virus that can infect the host cell and deliver the foreign DNA ( Figure 17.9 ) .", "question": { "cloze_format": "Gene therapy can be used to introduce foreign DNA into cells ________.", "normal_format": "How gene therapy can be used to introduce foreign DNA into cells?", "question_choices": [ "for molecular cloning", "by PCR", "of tissues to cure inheritable disease", "all of the above" ], "question_id": "fs-id1448379", "question_text": "Gene therapy can be used to introduce foreign DNA into cells ________." }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 1, "ans_text": "an organic insecticide produced by bacteria" }, "bloom": null, "hl_context": "<hl> Bacillus thuringiensis ( Bt ) is a bacterium that produces protein crystals during sporulation that are toxic to many insect species that affect plants . <hl> Bt toxin has to be ingested by insects for the toxin to be activated . Insects that have eaten Bt toxin stop feeding on the plants within a few hours . After the toxin is activated in the intestines of the insects , death occurs within a couple of days . Modern biotechnology has allowed plants to encode their own crystal Bt toxin that acts against insects . The crystal toxin genes have been cloned from Bt and introduced into plants . <hl> Bt toxin has been found to be safe for the environment , non-toxic to humans and other mammals , and is approved for use by organic farmers as a natural insecticide . <hl>", "hl_sentences": "Bacillus thuringiensis ( Bt ) is a bacterium that produces protein crystals during sporulation that are toxic to many insect species that affect plants . Bt toxin has been found to be safe for the environment , non-toxic to humans and other mammals , and is approved for use by organic farmers as a natural insecticide .", "question": { "cloze_format": "Bt toxin is considered to be ________.", "normal_format": "What is the Bt toxin considered to be?", "question_choices": [ "a gene for modifying insect DNA", "an organic insecticide produced by bacteria", "useful for humans to fight against insects", "a recombinant protein" ], "question_id": "fs-id1014698", "question_text": "Bt toxin is considered to be ________." }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 3, "ans_text": "all of the above" }, "bloom": null, "hl_context": "<hl> The first GM crop to be introduced into the market was the Flavr Savr Tomato produced in 1994 . <hl> <hl> Antisense RNA technology was used to slow down the process of softening and rotting caused by fungal infections , which led to increased shelf life of the GM tomatoes . <hl> <hl> Additional genetic modification improved the flavor of this tomato . <hl> <hl> The Flavr Savr tomato did not successfully stay in the market because of problems maintaining and shipping the crop . <hl> 17.2 Mapping Genomes Learning Objectives By the end of this section , you will be able to :", "hl_sentences": "The first GM crop to be introduced into the market was the Flavr Savr Tomato produced in 1994 . Antisense RNA technology was used to slow down the process of softening and rotting caused by fungal infections , which led to increased shelf life of the GM tomatoes . Additional genetic modification improved the flavor of this tomato . The Flavr Savr tomato did not successfully stay in the market because of problems maintaining and shipping the crop .", "question": { "cloze_format": "The Flavr Savr Tomato ___ .", "normal_format": "What is the Flavr Savr Tomato?", "question_choices": [ "is a variety of vine-ripened tomato in the supermarket", "was created to have better flavor and shelf-life", "does not undergo soft rot", "all of the above" ], "question_id": "fs-id1768985", "question_text": "The Flavr Savr Tomato:" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 1, "ans_text": "unique sequences in the genome" }, "bloom": null, "hl_context": "A physical map provides detail of the actual physical distance between genetic markers , as well as the number of nucleotides . There are three methods used to create a physical map : cytogenetic mapping , radiation hybrid mapping , and sequence mapping . Cytogenetic mapping uses information obtained by microscopic analysis of stained sections of the chromosome ( Figure 17.12 ) . It is possible to determine the approximate distance between genetic markers using cytogenetic mapping , but not the exact distance ( number of base pairs ) . Radiation hybrid mapping uses radiation , such as x-rays , to break the DNA into fragments . The amount of radiation can be adjusted to create smaller or larger fragments . This technique overcomes the limitation of genetic mapping and is not affected by increased or decreased recombination frequency . Sequence mapping resulted from DNA sequencing technology that allowed for the creation of detailed physical maps with distances measured in terms of the number of base pairs . The creation of genomic libraries and complementary DNA ( cDNA ) libraries ( collections of cloned sequences or all DNA from a genome ) has sped up the process of physical mapping . <hl> A genetic site used to generate a physical map with sequencing technology ( a sequence-tagged site , or STS ) is a unique sequence in the genome with a known exact chromosomal location . <hl> <hl> An expressed sequence tag ( EST ) and a single sequence length polymorphism ( SSLP ) are common STSs . <hl> <hl> An EST is a short STS that is identified with cDNA libraries , while SSLPs are obtained from known genetic markers and provide a link between genetic maps and physical maps . <hl>", "hl_sentences": "A genetic site used to generate a physical map with sequencing technology ( a sequence-tagged site , or STS ) is a unique sequence in the genome with a known exact chromosomal location . An expressed sequence tag ( EST ) and a single sequence length polymorphism ( SSLP ) are common STSs . An EST is a short STS that is identified with cDNA libraries , while SSLPs are obtained from known genetic markers and provide a link between genetic maps and physical maps .", "question": { "cloze_format": "ESTs are ________.", "normal_format": "What are ESTs?", "question_choices": [ "generated after a cDNA library is made", "unique sequences in the genome", "useful for mapping using sequence information", "all of the above" ], "question_id": "fs-id1425631", "question_text": "ESTs are ________." }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 0, "ans_text": "is used to create a physical map" }, "bloom": null, "hl_context": "Genomics is the study of entire genomes , including the complete set of genes , their nucleotide sequence and organization , and their interactions within a species and with other species . Genome mapping is the process of finding the locations of genes on each chromosome . The maps created by genome mapping are comparable to the maps that we use to navigate streets . A genetic map is an illustration that lists genes and their location on a chromosome . Genetic maps provide the big picture ( similar to a map of interstate highways ) and use genetic markers ( similar to landmarks ) . <hl> A genetic marker is a gene or sequence on a chromosome that co-segregates ( shows genetic linkage ) with a specific trait . <hl> <hl> Early geneticists called this linkage analysis . <hl> <hl> Physical maps present the intimate details of smaller regions of the chromosomes ( similar to a detailed road map ) . <hl> <hl> A physical map is a representation of the physical distance , in nucleotides , between genes or genetic markers . <hl> <hl> Both genetic linkage maps and physical maps are required to build a complete picture of the genome . <hl> Having a complete map of the genome makes it easier for researchers to study individual genes . Human genome maps help researchers in their efforts to identify human disease-causing genes related to illnesses like cancer , heart disease , and cystic fibrosis . Genome mapping can be used in a variety of other applications , such as using live microbes to clean up pollutants or even prevent pollution . Research involving plant genome mapping may lead to producing higher crop yields or developing plants that better adapt to climate change .", "hl_sentences": "A genetic marker is a gene or sequence on a chromosome that co-segregates ( shows genetic linkage ) with a specific trait . Early geneticists called this linkage analysis . Physical maps present the intimate details of smaller regions of the chromosomes ( similar to a detailed road map ) . A physical map is a representation of the physical distance , in nucleotides , between genes or genetic markers . Both genetic linkage maps and physical maps are required to build a complete picture of the genome .", "question": { "cloze_format": "Linkage analysis ________.", "normal_format": "Which of the following is correct about linkage analysis?", "question_choices": [ "is used to create a physical map", "is based on the natural recombination process", "requires radiation hybrid mapping", "involves breaking and re-joining of DNA artificially" ], "question_id": "fs-id1968258", "question_text": "Linkage analysis ________." }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 1, "ans_text": "crossing over" }, "bloom": "1", "hl_context": "Observations that certain traits were always linked and certain others were not linked came from studying the offspring of crosses between parents with different traits . For example , in experiments performed on the garden pea , it was discovered that the color of the flower and shape of the plant ’ s pollen were linked traits , and therefore the genes encoding these traits were in close proximity on the same chromosome . <hl> The exchange of DNA between homologous pairs of chromosomes is called genetic recombination , which occurs by the crossing over of DNA between homologous strands of DNA , such as nonsister chromatids . <hl> Linkage analysis involves studying the recombination frequency between any two genes . The greater the distance between two genes , the higher the chance that a recombination event will occur between them , and the higher the recombination frequency between them . Two possibilities for recombination between two nonsister chromatids during meiosis are shown in Figure 17.11 . If the recombination frequency between two genes is less than 50 percent , they are said to be linked .", "hl_sentences": "The exchange of DNA between homologous pairs of chromosomes is called genetic recombination , which occurs by the crossing over of DNA between homologous strands of DNA , such as nonsister chromatids .", "question": { "cloze_format": "Genetic recombination occurs by the process of ___ .", "normal_format": "Genetic recombination occurs by which process?", "question_choices": [ "independent assortment", "crossing over", "chromosome segregation", "sister chromatids" ], "question_id": "fs-id1418957", "question_text": "Genetic recombination occurs by which process?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 0, "ans_text": "genetically similar" }, "bloom": null, "hl_context": "<hl> The generation of genetic maps requires markers , just as a road map requires landmarks ( such as rivers and mountains ) . <hl> Early genetic maps were based on the use of known genes as markers . More sophisticated markers , including those based on non-coding DNA , are now used to compare the genomes of individuals in a population . <hl> Although individuals of a given species are genetically similar , they are not identical ; every individual has a unique set of traits . <hl> These minor differences in the genome between individuals in a population are useful for the purposes of genetic mapping . In general , a good genetic marker is a region on the chromosome that shows variability or polymorphism ( multiple forms ) in the population .", "hl_sentences": "The generation of genetic maps requires markers , just as a road map requires landmarks ( such as rivers and mountains ) . Although individuals of a given species are genetically similar , they are not identical ; every individual has a unique set of traits .", "question": { "cloze_format": "Individual genetic maps in a given species are ___ .", "normal_format": "What are individual genetic maps in a given species?", "question_choices": [ "genetically similar", "genetically identical", "genetically dissimilar", "not useful in species analysis" ], "question_id": "fs-id2609949", "question_text": "Individual genetic maps in a given species are:" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 3, "ans_text": "cytogenetic mapping" }, "bloom": null, "hl_context": "A physical map provides detail of the actual physical distance between genetic markers , as well as the number of nucleotides . There are three methods used to create a physical map : cytogenetic mapping , radiation hybrid mapping , and sequence mapping . <hl> Cytogenetic mapping uses information obtained by microscopic analysis of stained sections of the chromosome ( Figure 17.12 ) . <hl> It is possible to determine the approximate distance between genetic markers using cytogenetic mapping , but not the exact distance ( number of base pairs ) . Radiation hybrid mapping uses radiation , such as x-rays , to break the DNA into fragments . The amount of radiation can be adjusted to create smaller or larger fragments . This technique overcomes the limitation of genetic mapping and is not affected by increased or decreased recombination frequency . Sequence mapping resulted from DNA sequencing technology that allowed for the creation of detailed physical maps with distances measured in terms of the number of base pairs . The creation of genomic libraries and complementary DNA ( cDNA ) libraries ( collections of cloned sequences or all DNA from a genome ) has sped up the process of physical mapping . A genetic site used to generate a physical map with sequencing technology ( a sequence-tagged site , or STS ) is a unique sequence in the genome with a known exact chromosomal location . An expressed sequence tag ( EST ) and a single sequence length polymorphism ( SSLP ) are common STSs . An EST is a short STS that is identified with cDNA libraries , while SSLPs are obtained from known genetic markers and provide a link between genetic maps and physical maps .", "hl_sentences": "Cytogenetic mapping uses information obtained by microscopic analysis of stained sections of the chromosome ( Figure 17.12 ) .", "question": { "cloze_format": "Information obtained by microscopic analysis of stained chromosomes is used in ___ .", "normal_format": "Where is information obtained by microscopic analysis of stained chromosomes used in?", "question_choices": [ "radiation hybrid mapping", "sequence mapping", "RFLP mapping", "cytogenetic mapping" ], "question_id": "fs-id2386026", "question_text": "Information obtained by microscopic analysis of stained chromosomes is used in:" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 0, "ans_text": "uses labeled ddNTPs" }, "bloom": null, "hl_context": "<hl> The basic sequencing technique used in all modern day sequencing projects is the chain termination method ( also known as the dideoxy method ) , which was developed by Fred Sanger in the 1970s . <hl> <hl> The chain termination method involves DNA replication of a single-stranded template with the use of a primer and a regular deoxynucleotide ( dNTP ) , which is a monomer , or a single unit , of DNA . <hl> <hl> The primer and dNTP are mixed with a small proportion of fluorescently labeled dideoxynucleotides ( ddNTPs ) . <hl> <hl> The ddNTPs are monomers that are missing a hydroxyl group ( – OH ) at the site at which another nucleotide usually attaches to form a chain ( Figure 17.13 ) . <hl> <hl> Each ddNTP is labeled with a different color of fluorophore . <hl> Every time a ddNTP is incorporated in the growing complementary strand , it terminates the process of DNA replication , which results in multiple short strands of replicated DNA that are each terminated at a different point during replication . When the reaction mixture is processed by gel electrophoresis after being separated into single strands , the multiple newly replicated DNA strands form a ladder because of the differing sizes . <hl> Because the ddNTPs are fluorescently labeled , each band on the gel reflects the size of the DNA strand and the ddNTP that terminated the reaction . <hl> The different colors of the fluorophore-labeled ddNTPs help identify the ddNTP incorporated at that position . Reading the gel on the basis of the color of each band on the ladder produces the sequence of the template strand ( Figure 17.14 ) .", "hl_sentences": "The basic sequencing technique used in all modern day sequencing projects is the chain termination method ( also known as the dideoxy method ) , which was developed by Fred Sanger in the 1970s . The chain termination method involves DNA replication of a single-stranded template with the use of a primer and a regular deoxynucleotide ( dNTP ) , which is a monomer , or a single unit , of DNA . The primer and dNTP are mixed with a small proportion of fluorescently labeled dideoxynucleotides ( ddNTPs ) . The ddNTPs are monomers that are missing a hydroxyl group ( – OH ) at the site at which another nucleotide usually attaches to form a chain ( Figure 17.13 ) . Each ddNTP is labeled with a different color of fluorophore . Because the ddNTPs are fluorescently labeled , each band on the gel reflects the size of the DNA strand and the ddNTP that terminated the reaction .", "question": { "cloze_format": "The chain termination method of sequencing ___.", "normal_format": "What is the chain termination method of sequencing?", "question_choices": [ "uses labeled ddNTPs", "uses only dideoxynucleotides", "uses only deoxynucleotides", "uses labeled dNTPs" ], "question_id": "fs-id3103556", "question_text": "The chain termination method of sequencing:" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 3, "ans_text": "all of the above" }, "bloom": null, "hl_context": "DNA microarrays are methods used to detect gene expression by analyzing an array of DNA fragments that are fixed to a glass slide or a silicon chip to identify active genes and identify sequences . Almost one million genotypic abnormalities can be discovered using microarrays , whereas whole-genome sequencing can provide information about all six billion base pairs in the human genome . Although the study of medical applications of genome sequencing is interesting , this discipline tends to dwell on abnormal gene function . Knowledge of the entire genome will allow future onset diseases and other genetic disorders to be discovered early , which will allow for more informed decisions to be made about lifestyle , medication , and having children . <hl> Genomics is still in its infancy , although someday it may become routine to use whole-genome sequencing to screen every newborn to detect genetic abnormalities . <hl> <hl> In addition to disease and medicine , genomics can contribute to the development of novel enzymes that convert biomass to biofuel , which results in higher crop and fuel production , and lower cost to the consumer . <hl> <hl> This knowledge should allow better methods of control over the microbes that are used in the production of biofuels . <hl> <hl> Genomics could also improve the methods used to monitor the impact of pollutants on ecosystems and help clean up environmental contaminants . <hl> <hl> Genomics has allowed for the development of agrochemicals and pharmaceuticals that could benefit medical science and agriculture . <hl> For example , whole-exome sequencing is a lower-cost alternative to whole genome sequencing . In exome sequencing , only the coding , exon-producing regions of the DNA are sequenced . In 2010 , whole-exome sequencing was used to save a young boy whose intestines had multiple mysterious abscesses . The child had several colon operations with no relief . Finally , whole-exome sequencing was performed , which revealed a defect in a pathway that controls apoptosis ( programmed cell death ) . A bone-marrow transplant was used to overcome this genetic disorder , leading to a cure for the boy . <hl> He was the first person to be successfully treated based on a diagnosis made by whole-exome sequencing . <hl> Today , human genome sequencing is more readily available and can be completed in a day or two for about $ 1000 . Strategies Used in Sequencing Projects Although there have been significant advances in the medical sciences in recent years , doctors are still confounded by some diseases , and they are using whole-genome sequencing to get to the bottom of the problem . <hl> Whole-genome sequencing is a process that determines the DNA sequence of an entire genome . <hl> <hl> Whole-genome sequencing is a brute-force approach to problem solving when there is a genetic basis at the core of a disease . <hl> <hl> Several laboratories now provide services to sequence , analyze , and interpret entire genomes . <hl>", "hl_sentences": "Genomics is still in its infancy , although someday it may become routine to use whole-genome sequencing to screen every newborn to detect genetic abnormalities . In addition to disease and medicine , genomics can contribute to the development of novel enzymes that convert biomass to biofuel , which results in higher crop and fuel production , and lower cost to the consumer . This knowledge should allow better methods of control over the microbes that are used in the production of biofuels . Genomics could also improve the methods used to monitor the impact of pollutants on ecosystems and help clean up environmental contaminants . Genomics has allowed for the development of agrochemicals and pharmaceuticals that could benefit medical science and agriculture . He was the first person to be successfully treated based on a diagnosis made by whole-exome sequencing . Whole-genome sequencing is a process that determines the DNA sequence of an entire genome . Whole-genome sequencing is a brute-force approach to problem solving when there is a genetic basis at the core of a disease . Several laboratories now provide services to sequence , analyze , and interpret entire genomes .", "question": { "cloze_format": "Whole-genome sequencing can be used for advances in ___ .", "normal_format": "For which advances the whole-genome sequencing can be used?", "question_choices": [ "the medical field", "agriculture", "biofuels", "all of the above" ], "question_id": "fs-id2164620", "question_text": "Whole-genome sequencing can be used for advances in:" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 3, "ans_text": "all of the above" }, "bloom": null, "hl_context": "<hl> Predicting the risk of disease involves screening currently healthy individuals by genome analysis at the individual level . <hl> <hl> Intervention with lifestyle changes and drugs can be recommended before disease onset . <hl> <hl> However , this approach is most applicable when the problem resides within a single gene defect . <hl> <hl> Such defects only account for approximately 5 percent of diseases in developed countries . <hl> <hl> Most of the common diseases , such as heart disease , are multi-factored or polygenic , which is a phenotypic characteristic that involves two or more genes , and also involve environmental factors such as diet . <hl> In April 2010 , scientists at Stanford University published the genome analysis of a healthy individual ( Stephen Quake , a scientist at Stanford University , who had his genome sequenced ); the analysis predicted his propensity to acquire various diseases . A risk assessment was performed to analyze Quake ’ s percentage of risk for 55 different medical conditions . A rare genetic mutation was found , which showed him to be at risk for sudden heart attack . He was also predicted to have a 23 percent risk of developing prostate cancer and a 1.4 percent risk of developing Alzheimer ’ s . The scientists used databases and several publications to analyze the genomic data . <hl> Even though genomic sequencing is becoming more affordable and analytical tools are becoming more reliable , ethical issues surrounding genomic analysis at a population level remain to be addressed . <hl> <hl> It sounds great to have all the knowledge we can get from whole-genome sequencing ; however , humans have a responsibility to use this knowledge wisely . <hl> <hl> Otherwise , it could be easy to misuse the power of such knowledge , leading to discrimination based on a person's genetics , human genetic engineering , and other ethical concerns . <hl> <hl> This information could also lead to legal issues regarding health and privacy . <hl> 17.4 Applying Genomics Learning Objectives By the end of this section , you will be able to :", "hl_sentences": "Predicting the risk of disease involves screening currently healthy individuals by genome analysis at the individual level . Intervention with lifestyle changes and drugs can be recommended before disease onset . However , this approach is most applicable when the problem resides within a single gene defect . Such defects only account for approximately 5 percent of diseases in developed countries . Most of the common diseases , such as heart disease , are multi-factored or polygenic , which is a phenotypic characteristic that involves two or more genes , and also involve environmental factors such as diet . Even though genomic sequencing is becoming more affordable and analytical tools are becoming more reliable , ethical issues surrounding genomic analysis at a population level remain to be addressed . It sounds great to have all the knowledge we can get from whole-genome sequencing ; however , humans have a responsibility to use this knowledge wisely . Otherwise , it could be easy to misuse the power of such knowledge , leading to discrimination based on a person's genetics , human genetic engineering , and other ethical concerns . This information could also lead to legal issues regarding health and privacy .", "question": { "cloze_format": "Sequencing an individual person’s genome ___ .", "normal_format": "What is sequencing an individual person’s genome?", "question_choices": [ "is currently possible", "could lead to legal issues regarding discrimination and privacy", "could help make informed choices about medical treatment ", "all of the above" ], "question_id": "fs-id2936033", "question_text": "Sequencing an individual person’s genome" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 1, "ans_text": "the ethics of using information from genomes at the individual level" }, "bloom": null, "hl_context": "Predicting the risk of disease involves screening currently healthy individuals by genome analysis at the individual level . Intervention with lifestyle changes and drugs can be recommended before disease onset . However , this approach is most applicable when the problem resides within a single gene defect . Such defects only account for approximately 5 percent of diseases in developed countries . Most of the common diseases , such as heart disease , are multi-factored or polygenic , which is a phenotypic characteristic that involves two or more genes , and also involve environmental factors such as diet . In April 2010 , scientists at Stanford University published the genome analysis of a healthy individual ( Stephen Quake , a scientist at Stanford University , who had his genome sequenced ); the analysis predicted his propensity to acquire various diseases . A risk assessment was performed to analyze Quake ’ s percentage of risk for 55 different medical conditions . A rare genetic mutation was found , which showed him to be at risk for sudden heart attack . He was also predicted to have a 23 percent risk of developing prostate cancer and a 1.4 percent risk of developing Alzheimer ’ s . The scientists used databases and several publications to analyze the genomic data . <hl> Even though genomic sequencing is becoming more affordable and analytical tools are becoming more reliable , ethical issues surrounding genomic analysis at a population level remain to be addressed . <hl> <hl> Predicting Disease Risk at the Individual Level <hl>", "hl_sentences": "Even though genomic sequencing is becoming more affordable and analytical tools are becoming more reliable , ethical issues surrounding genomic analysis at a population level remain to be addressed . Predicting Disease Risk at the Individual Level", "question": { "cloze_format": "The most challenging issue facing genome sequencing is ___.", "normal_format": "What is the most challenging issue facing genome sequencing?", "question_choices": [ "the inability to develop fast and accurate sequencing techniques", "the ethics of using information from genomes at the individual level", "the availability and stability of DNA", "all of the above" ], "question_id": "fs-id2720660", "question_text": "What is the most challenging issue facing genome sequencing?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 3, "ans_text": "all of the above" }, "bloom": null, "hl_context": "<hl> Genomics can reduce the trials and failures involved in scientific research to a certain extent , which could improve the quality and quantity of crop yields in agriculture . <hl> <hl> Linking traits to genes or gene signatures helps to improve crop breeding to generate hybrids with the most desirable qualities . <hl> <hl> Scientists use genomic data to identify desirable traits , and then transfer those traits to a different organism . <hl> <hl> Scientists are discovering how genomics can improve the quality and quantity of agricultural production . <hl> <hl> For example , scientists could use desirable traits to create a useful product or enhance an existing product , such as making a drought-sensitive crop more tolerant of the dry season . <hl> 17.5 Genomics and Proteomics Learning Objectives By the end of this section , you will be able to :", "hl_sentences": "Genomics can reduce the trials and failures involved in scientific research to a certain extent , which could improve the quality and quantity of crop yields in agriculture . Linking traits to genes or gene signatures helps to improve crop breeding to generate hybrids with the most desirable qualities . Scientists use genomic data to identify desirable traits , and then transfer those traits to a different organism . Scientists are discovering how genomics can improve the quality and quantity of agricultural production . For example , scientists could use desirable traits to create a useful product or enhance an existing product , such as making a drought-sensitive crop more tolerant of the dry season .", "question": { "cloze_format": "Genomics can be used in agriculture to ___.", "normal_format": "How Genomics can be used in agriculture?", "question_choices": [ "generate new hybrid strains", "improve disease resistance", "improve yield", "all of the above" ], "question_id": "fs-id2853936", "question_text": "Genomics can be used in agriculture to:" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 1, "ans_text": "a protein that is uniquely produced in a diseased state" }, "bloom": "1", "hl_context": "Genomes and proteomes of patients suffering from specific diseases are being studied to understand the genetic basis of the disease . The most prominent disease being studied with proteomic approaches is cancer . <hl> Proteomic approaches are being used to improve screening and early detection of cancer ; this is achieved by identifying proteins whose expression is affected by the disease process . <hl> <hl> An individual protein is called a biomarker , whereas a set of proteins with altered expression levels is called a protein signature . <hl> For a biomarker or protein signature to be useful as a candidate for early screening and detection of a cancer , it must be secreted in body fluids , such as sweat , blood , or urine , such that large-scale screenings can be performed in a non-invasive fashion . The current problem with using biomarkers for the early detection of cancer is the high rate of false-negative results . A false negative is an incorrect test result that should have been positive . In other words , many cases of cancer go undetected , which makes biomarkers unreliable . Some examples of protein biomarkers used in cancer detection are CA - 125 for ovarian cancer and PSA for prostate cancer . Protein signatures may be more reliable than biomarkers to detect cancer cells . Proteomics is also being used to develop individualized treatment plans , which involves the prediction of whether or not an individual will respond to specific drugs and the side effects that the individual may experience . Proteomics is also being used to predict the possibility of disease recurrence .", "hl_sentences": "Proteomic approaches are being used to improve screening and early detection of cancer ; this is achieved by identifying proteins whose expression is affected by the disease process . An individual protein is called a biomarker , whereas a set of proteins with altered expression levels is called a protein signature .", "question": { "cloze_format": "A biomarker is ___.", "normal_format": "What is a biomarker?", "question_choices": [ "the color coding of different genes", "a protein that is uniquely produced in a diseased state", "a molecule in the genome or proteome", "a marker that is genetically inherited" ], "question_id": "fs-id1956957", "question_text": "What is a biomarker?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 3, "ans_text": "a unique set of proteins present in a diseased state" }, "bloom": null, "hl_context": "Genomes and proteomes of patients suffering from specific diseases are being studied to understand the genetic basis of the disease . The most prominent disease being studied with proteomic approaches is cancer . <hl> Proteomic approaches are being used to improve screening and early detection of cancer ; this is achieved by identifying proteins whose expression is affected by the disease process . <hl> <hl> An individual protein is called a biomarker , whereas a set of proteins with altered expression levels is called a protein signature . <hl> For a biomarker or protein signature to be useful as a candidate for early screening and detection of a cancer , it must be secreted in body fluids , such as sweat , blood , or urine , such that large-scale screenings can be performed in a non-invasive fashion . The current problem with using biomarkers for the early detection of cancer is the high rate of false-negative results . A false negative is an incorrect test result that should have been positive . In other words , many cases of cancer go undetected , which makes biomarkers unreliable . Some examples of protein biomarkers used in cancer detection are CA - 125 for ovarian cancer and PSA for prostate cancer . Protein signatures may be more reliable than biomarkers to detect cancer cells . Proteomics is also being used to develop individualized treatment plans , which involves the prediction of whether or not an individual will respond to specific drugs and the side effects that the individual may experience . Proteomics is also being used to predict the possibility of disease recurrence .", "hl_sentences": "Proteomic approaches are being used to improve screening and early detection of cancer ; this is achieved by identifying proteins whose expression is affected by the disease process . An individual protein is called a biomarker , whereas a set of proteins with altered expression levels is called a protein signature .", "question": { "cloze_format": "A protein signature is ___ .", "normal_format": "What is a protein signature?", "question_choices": [ "the path followed by a protein after it is synthesized in the nucleus", "the path followed by a protein in the cytoplasm", "a protein expressed on the cell surface", "a unique set of proteins present in a diseased state" ], "question_id": "fs-id1236114", "question_text": "A protein signature is:" }, "references_are_paraphrase": null } ]
17
17.1 Biotechnology Learning Objectives By the end of this section, you will be able to: Describe gel electrophoresis Explain molecular and reproductive cloning Describe uses of biotechnology in medicine and agriculture Biotechnology is the use of biological agents for technological advancement. Biotechnology was used for breeding livestock and crops long before the scientific basis of these techniques was understood. Since the discovery of the structure of DNA in 1953, the field of biotechnology has grown rapidly through both academic research and private companies. The primary applications of this technology are in medicine (production of vaccines and antibiotics) and agriculture (genetic modification of crops, such as to increase yields). Biotechnology also has many industrial applications, such as fermentation, the treatment of oil spills, and the production of biofuels ( Figure 17.2 ). Basic Techniques to Manipulate Genetic Material (DNA and RNA) To understand the basic techniques used to work with nucleic acids, remember that nucleic acids are macromolecules made of nucleotides (a sugar, a phosphate, and a nitrogenous base) linked by phosphodiester bonds. The phosphate groups on these molecules each have a net negative charge. An entire set of DNA molecules in the nucleus is called the genome. DNA has two complementary strands linked by hydrogen bonds between the paired bases. The two strands can be separated by exposure to high temperatures (DNA denaturation) and can be reannealed by cooling. The DNA can be replicated by the DNA polymerase enzyme. Unlike DNA, which is located in the nucleus of eukaryotic cells, RNA molecules leave the nucleus. The most common type of RNA that is analyzed is the messenger RNA (mRNA) because it represents the protein-coding genes that are actively expressed. However, RNA molecules present some other challenges to analysis, as they are often less stable than DNA. DNA and RNA Extraction To study or manipulate nucleic acids, the DNA or RNA must first be isolated or extracted from the cells. Various techniques are used to extract different types of DNA ( Figure 17.3 ). Most nucleic acid extraction techniques involve steps to break open the cell and use enzymatic reactions to destroy all macromolecules that are not desired (such as degradation of unwanted molecules and separation from the DNA sample). Cells are broken using a lysis buffer (a solution which is mostly a detergent); lysis means “to split.” These enzymes break apart lipid molecules in the cell membranes and nuclear membranes. Macromolecules are inactivated using enzymes such as proteases that break down proteins, and ribonucleases (RNAses) that break down RNA. The DNA is then precipitated using alcohol. Human genomic DNA is usually visible as a gelatinous, white mass. The DNA samples can be stored frozen at –80°C for several years. RNA analysis is performed to study gene expression patterns in cells. RNA is naturally very unstable because RNAses are commonly present in nature and very difficult to inactivate. Similar to DNA, RNA extraction involves the use of various buffers and enzymes to inactivate macromolecules and preserve the RNA. Gel Electrophoresis Because nucleic acids are negatively charged ions at neutral or basic pH in an aqueous environment, they can be mobilized by an electric field. Gel electrophoresis is a technique used to separate molecules on the basis of size, using this charge. The nucleic acids can be separated as whole chromosomes or fragments. The nucleic acids are loaded into a slot near the negative electrode of a semisolid, porous gel matrix and pulled toward the positive electrode at the opposite end of the gel. Smaller molecules move through the pores in the gel faster than larger molecules; this difference in the rate of migration separates the fragments on the basis of size. There are molecular weight standard samples that can be run alongside the molecules to provide a size comparison. Nucleic acids in a gel matrix can be observed using various fluorescent or colored dyes. Distinct nucleic acid fragments appear as bands at specific distances from the top of the gel (the negative electrode end) on the basis of their size ( Figure 17.4 ). A mixture of genomic DNA fragments of varying sizes appear as a long smear, whereas uncut genomic DNA is usually too large to run through the gel and forms a single large band at the top of the gel. Amplification of Nucleic Acid Fragments by Polymerase Chain Reaction Although genomic DNA is visible to the naked eye when it is extracted in bulk, DNA analysis often requires focusing on one or more specific regions of the genome. Polymerase chain reaction ( PCR ) is a technique used to amplify specific regions of DNA for further analysis ( Figure 17.5 ). PCR is used for many purposes in laboratories, such as the cloning of gene fragments to analyze genetic diseases, identification of contaminant foreign DNA in a sample, and the amplification of DNA for sequencing. More practical applications include the determination of paternity and detection of genetic diseases. DNA fragments can also be amplified from an RNA template in a process called reverse transcriptase PCR (RT-PCR) . The first step is to recreate the original DNA template strand (called cDNA) by applying DNA nucleotides to the mRNA. This process is called reverse transcription. This requires the presence of an enzyme called reverse transcriptase. After the cDNA is made, regular PCR can be used to amplify it. Link to Learning Deepen your understanding of the polymerase chain reaction by clicking through this interactive exercise . Hybridization, Southern Blotting, and Northern Blotting Nucleic acid samples, such as fragmented genomic DNA and RNA extracts, can be probed for the presence of certain sequences. Short DNA fragments called probes are designed and labeled with radioactive or fluorescent dyes to aid detection. Gel electrophoresis separates the nucleic acid fragments according to their size. The fragments in the gel are then transferred onto a nylon membrane in a procedure called blotting ( Figure 17.6 ). The nucleic acid fragments that are bound to the surface of the membrane can then be probed with specific radioactively or fluorescently labeled probe sequences. When DNA is transferred to a nylon membrane, the technique is called Southern blotting , and when RNA is transferred to a nylon membrane, it is called northern blotting . Southern blots are used to detect the presence of certain DNA sequences in a given genome, and northern blots are used to detect gene expression. Molecular Cloning In general, the word “cloning” means the creation of a perfect replica; however, in biology, the re-creation of a whole organism is referred to as “reproductive cloning.” Long before attempts were made to clone an entire organism, researchers learned how to reproduce desired regions or fragments of the genome, a process that is referred to as molecular cloning. Cloning small fragments of the genome allows for the manipulation and study of specific genes (and their protein products), or noncoding regions in isolation. A plasmid (also called a vector) is a small circular DNA molecule that replicates independently of the chromosomal DNA. In cloning, the plasmid molecules can be used to provide a "folder" in which to insert a desired DNA fragment. Plasmids are usually introduced into a bacterial host for proliferation. In the bacterial context, the fragment of DNA from the human genome (or the genome of another organism that is being studied) is referred to as foreign DNA , or a transgene, to differentiate it from the DNA of the bacterium, which is called the host DNA . Plasmids occur naturally in bacterial populations (such as Escherichia coli ) and have genes that can contribute favorable traits to the organism, such as antibiotic resistance (the ability to be unaffected by antibiotics). Plasmids have been repurposed and engineered as vectors for molecular cloning and the large-scale production of important reagents, such as insulin and human growth hormone. An important feature of plasmid vectors is the ease with which a foreign DNA fragment can be introduced via the multiple cloning site (MCS) . The MCS is a short DNA sequence containing multiple sites that can be cut with different commonly available restriction endonucleases. Restriction endonucleases recognize specific DNA sequences and cut them in a predictable manner; they are naturally produced by bacteria as a defense mechanism against foreign DNA. Many restriction endonucleases make staggered cuts in the two strands of DNA, such that the cut ends have a 2- or 4-base single-stranded overhang. Because these overhangs are capable of annealing with complementary overhangs, these are called “sticky ends.” Addition of an enzyme called DNA ligase permanently joins the DNA fragments via phosphodiester bonds. In this way, any DNA fragment generated by restriction endonuclease cleavage can be spliced between the two ends of a plasmid DNA that has been cut with the same restriction endonuclease ( Figure 17.7 ). Recombinant DNA Molecules Plasmids with foreign DNA inserted into them are called recombinant DNA molecules because they are created artificially and do not occur in nature. They are also called chimeric molecules because the origin of different parts of the molecules can be traced back to different species of biological organisms or even to chemical synthesis. Proteins that are expressed from recombinant DNA molecules are called recombinant proteins . Not all recombinant plasmids are capable of expressing genes. The recombinant DNA may need to be moved into a different vector (or host) that is better designed for gene expression. Plasmids may also be engineered to express proteins only when stimulated by certain environmental factors, so that scientists can control the expression of the recombinant proteins. Visual Connection You are working in a molecular biology lab and, unbeknownst to you, your lab partner left the foreign genomic DNA that you are planning to clone on the lab bench overnight instead of storing it in the freezer. As a result, it was degraded by nucleases, but still used in the experiment. The plasmid, on the other hand, is fine. What results would you expect from your molecular cloning experiment? There will be no colonies on the bacterial plate. There will be blue colonies only. There will be blue and white colonies. The will be white colonies only. Link to Learning View an animation of recombination in cloning from the DNA Learning Center. Cellular Cloning Unicellular organisms, such as bacteria and yeast, naturally produce clones of themselves when they replicate asexually by binary fission; this is known as cellular cloning . The nuclear DNA duplicates by the process of mitosis, which creates an exact replica of the genetic material. Reproductive Cloning Reproductive cloning is a method used to make a clone or an identical copy of an entire multicellular organism. Most multicellular organisms undergo reproduction by sexual means, which involves genetic hybridization of two individuals (parents), making it impossible for generation of an identical copy or a clone of either parent. Recent advances in biotechnology have made it possible to artificially induce asexual reproduction of mammals in the laboratory. Parthenogenesis, or “virgin birth,” occurs when an embryo grows and develops without the fertilization of the egg occurring; this is a form of asexual reproduction. An example of parthenogenesis occurs in species in which the female lays an egg and if the egg is fertilized, it is a diploid egg and the individual develops into a female; if the egg is not fertilized, it remains a haploid egg and develops into a male. The unfertilized egg is called a parthenogenic, or virgin, egg. Some insects and reptiles lay parthenogenic eggs that can develop into adults. Sexual reproduction requires two cells; when the haploid egg and sperm cells fuse, a diploid zygote results. The zygote nucleus contains the genetic information to produce a new individual. However, early embryonic development requires the cytoplasmic material contained in the egg cell. This idea forms the basis for reproductive cloning. Therefore, if the haploid nucleus of an egg cell is replaced with a diploid nucleus from the cell of any individual of the same species (called a donor), it will become a zygote that is genetically identical to the donor. Somatic cell nuclear transfer is the technique of transferring a diploid nucleus into an enucleated egg. It can be used for either therapeutic cloning or reproductive cloning. The first cloned animal was Dolly, a sheep who was born in 1996. The success rate of reproductive cloning at the time was very low. Dolly lived for seven years and died of respiratory complications ( Figure 17.8 ). There is speculation that because the cell DNA belongs to an older individual, the age of the DNA may affect the life expectancy of a cloned individual. Since Dolly, several animals such as horses, bulls, and goats have been successfully cloned, although these individuals often exhibit facial, limb, and cardiac abnormalities. There have been attempts at producing cloned human embryos as sources of embryonic stem cells, sometimes referred to as cloning for therapeutic purposes. Therapeutic cloning produces stem cells to attempt to remedy detrimental diseases or defects (unlike reproductive cloning, which aims to reproduce an organism). Still, therapeutic cloning efforts have met with resistance because of bioethical considerations. Visual Connection Do you think Dolly was a Finn-Dorset or a Scottish Blackface sheep? Genetic Engineering Genetic engineering is the alteration of an organism’s genotype using recombinant DNA technology to modify an organism’s DNA to achieve desirable traits. The addition of foreign DNA in the form of recombinant DNA vectors generated by molecular cloning is the most common method of genetic engineering. The organism that receives the recombinant DNA is called a genetically modified organism (GMO). If the foreign DNA that is introduced comes from a different species, the host organism is called transgenic . Bacteria, plants, and animals have been genetically modified since the early 1970s for academic, medical, agricultural, and industrial purposes. In the US, GMOs such as Roundup-ready soybeans and borer-resistant corn are part of many common processed foods. Gene Targeting Although classical methods of studying the function of genes began with a given phenotype and determined the genetic basis of that phenotype, modern techniques allow researchers to start at the DNA sequence level and ask: "What does this gene or DNA element do?" This technique, called reverse genetics, has resulted in reversing the classic genetic methodology. This method would be similar to damaging a body part to determine its function. An insect that loses a wing cannot fly, which means that the function of the wing is flight. The classical genetic method would compare insects that cannot fly with insects that can fly, and observe that the non-flying insects have lost wings. Similarly, mutating or deleting genes provides researchers with clues about gene function. The methods used to disable gene function are collectively called gene targeting. Gene targeting is the use of recombinant DNA vectors to alter the expression of a particular gene, either by introducing mutations in a gene, or by eliminating the expression of a certain gene by deleting a part or all of the gene sequence from the genome of an organism. Biotechnology in Medicine and Agriculture It is easy to see how biotechnology can be used for medicinal purposes. Knowledge of the genetic makeup of our species, the genetic basis of heritable diseases, and the invention of technology to manipulate and fix mutant genes provides methods to treat the disease. Biotechnology in agriculture can enhance resistance to disease, pest, and environmental stress, and improve both crop yield and quality. Genetic Diagnosis and Gene Therapy The process of testing for suspected genetic defects before administering treatment is called genetic diagnosis by genetic testing . Depending on the inheritance patterns of a disease-causing gene, family members are advised to undergo genetic testing. For example, women diagnosed with breast cancer are usually advised to have a biopsy so that the medical team can determine the genetic basis of cancer development. Treatment plans are based on the findings of genetic tests that determine the type of cancer. If the cancer is caused by inherited gene mutations, other female relatives are also advised to undergo genetic testing and periodic screening for breast cancer. Genetic testing is also offered for fetuses (or embryos with in vitro fertilization) to determine the presence or absence of disease-causing genes in families with specific debilitating diseases. Gene therapy is a genetic engineering technique used to cure disease. In its simplest form, it involves the introduction of a good gene at a random location in the genome to aid the cure of a disease that is caused by a mutated gene. The good gene is usually introduced into diseased cells as part of a vector transmitted by a virus that can infect the host cell and deliver the foreign DNA ( Figure 17.9 ). More advanced forms of gene therapy try to correct the mutation at the original site in the genome, such as is the case with treatment of severe combined immunodeficiency (SCID). Production of Vaccines, Antibiotics, and Hormones Traditional vaccination strategies use weakened or inactive forms of microorganisms to mount the initial immune response. Modern techniques use the genes of microorganisms cloned into vectors to mass produce the desired antigen. The antigen is then introduced into the body to stimulate the primary immune response and trigger immune memory. Genes cloned from the influenza virus have been used to combat the constantly changing strains of this virus. Antibiotics are a biotechnological product. They are naturally produced by microorganisms, such as fungi, to attain an advantage over bacterial populations. Antibiotics are produced on a large scale by cultivating and manipulating fungal cells. Recombinant DNA technology was used to produce large-scale quantities of human insulin in E. coli as early as 1978. Previously, it was only possible to treat diabetes with pig insulin, which caused allergic reactions in humans because of differences in the gene product. In addition, human growth hormone (HGH) is used to treat growth disorders in children. The HGH gene was cloned from a cDNA library and inserted into E. coli cells by cloning it into a bacterial vector. Transgenic Animals Although several recombinant proteins used in medicine are successfully produced in bacteria, some proteins require a eukaryotic animal host for proper processing. For this reason, the desired genes are cloned and expressed in animals, such as sheep, goats, chickens, and mice. Animals that have been modified to express recombinant DNA are called transgenic animals. Several human proteins are expressed in the milk of transgenic sheep and goats, and some are expressed in the eggs of chickens. Mice have been used extensively for expressing and studying the effects of recombinant genes and mutations. Transgenic Plants Manipulating the DNA of plants (i.e., creating GMOs) has helped to create desirable traits, such as disease resistance, herbicide and pesticide resistance, better nutritional value, and better shelf-life ( Figure 17.10 ). Plants are the most important source of food for the human population. Farmers developed ways to select for plant varieties with desirable traits long before modern-day biotechnology practices were established. Plants that have received recombinant DNA from other species are called transgenic plants. Because they are not natural, transgenic plants and other GMOs are closely monitored by government agencies to ensure that they are fit for human consumption and do not endanger other plant and animal life. Because foreign genes can spread to other species in the environment, extensive testing is required to ensure ecological stability. Staples like corn, potatoes, and tomatoes were the first crop plants to be genetically engineered. Transformation of Plants Using Agrobacterium tumefaciens Gene transfer occurs naturally between species in microbial populations. Many viruses that cause human diseases, such as cancer, act by incorporating their DNA into the human genome. In plants, tumors caused by the bacterium Agrobacterium tumefaciens occur by transfer of DNA from the bacterium to the plant. Although the tumors do not kill the plants, they make the plants stunted and more susceptible to harsh environmental conditions. Many plants, such as walnuts, grapes, nut trees, and beets, are affected by A. tumefaciens . The artificial introduction of DNA into plant cells is more challenging than in animal cells because of the thick plant cell wall. Researchers used the natural transfer of DNA from Agrobacterium to a plant host to introduce DNA fragments of their choice into plant hosts. In nature, the disease-causing A. tumefaciens have a set of plasmids, called the Ti plasmids (tumor-inducing plasmids), that contain genes for the production of tumors in plants. DNA from the Ti plasmid integrates into the infected plant cell’s genome. Researchers manipulate the Ti plasmids to remove the tumor-causing genes and insert the desired DNA fragment for transfer into the plant genome. The Ti plasmids carry antibiotic resistance genes to aid selection and can be propagated in E. coli cells as well. The Organic Insecticide Bacillus thuringiensis Bacillus thuringiensis (Bt) is a bacterium that produces protein crystals during sporulation that are toxic to many insect species that affect plants. Bt toxin has to be ingested by insects for the toxin to be activated. Insects that have eaten Bt toxin stop feeding on the plants within a few hours. After the toxin is activated in the intestines of the insects, death occurs within a couple of days. Modern biotechnology has allowed plants to encode their own crystal Bt toxin that acts against insects. The crystal toxin genes have been cloned from Bt and introduced into plants. Bt toxin has been found to be safe for the environment, non-toxic to humans and other mammals, and is approved for use by organic farmers as a natural insecticide. Flavr Savr Tomato The first GM crop to be introduced into the market was the Flavr Savr Tomato produced in 1994. Antisense RNA technology was used to slow down the process of softening and rotting caused by fungal infections, which led to increased shelf life of the GM tomatoes. Additional genetic modification improved the flavor of this tomato. The Flavr Savr tomato did not successfully stay in the market because of problems maintaining and shipping the crop. 17.2 Mapping Genomes Learning Objectives By the end of this section, you will be able to: Define genomics Describe genetic and physical maps Describe genomic mapping methods Genomics is the study of entire genomes, including the complete set of genes, their nucleotide sequence and organization, and their interactions within a species and with other species. Genome mapping is the process of finding the locations of genes on each chromosome. The maps created by genome mapping are comparable to the maps that we use to navigate streets. A genetic map is an illustration that lists genes and their location on a chromosome. Genetic maps provide the big picture (similar to a map of interstate highways) and use genetic markers (similar to landmarks). A genetic marker is a gene or sequence on a chromosome that co-segregates (shows genetic linkage) with a specific trait. Early geneticists called this linkage analysis. Physical maps present the intimate details of smaller regions of the chromosomes (similar to a detailed road map). A physical map is a representation of the physical distance, in nucleotides, between genes or genetic markers. Both genetic linkage maps and physical maps are required to build a complete picture of the genome. Having a complete map of the genome makes it easier for researchers to study individual genes. Human genome maps help researchers in their efforts to identify human disease-causing genes related to illnesses like cancer, heart disease, and cystic fibrosis. Genome mapping can be used in a variety of other applications, such as using live microbes to clean up pollutants or even prevent pollution. Research involving plant genome mapping may lead to producing higher crop yields or developing plants that better adapt to climate change. Genetic Maps The study of genetic maps begins with linkage analysis , a procedure that analyzes the recombination frequency between genes to determine if they are linked or show independent assortment. The term linkage was used before the discovery of DNA. Early geneticists relied on the observation of phenotypic changes to understand the genotype of an organism. Shortly after Gregor Mendel (the father of modern genetics) proposed that traits were determined by what are now known as genes, other researchers observed that different traits were often inherited together, and thereby deduced that the genes were physically linked by being located on the same chromosome. The mapping of genes relative to each other based on linkage analysis led to the development of the first genetic maps. Observations that certain traits were always linked and certain others were not linked came from studying the offspring of crosses between parents with different traits. For example, in experiments performed on the garden pea, it was discovered that the color of the flower and shape of the plant’s pollen were linked traits, and therefore the genes encoding these traits were in close proximity on the same chromosome. The exchange of DNA between homologous pairs of chromosomes is called genetic recombination , which occurs by the crossing over of DNA between homologous strands of DNA, such as nonsister chromatids. Linkage analysis involves studying the recombination frequency between any two genes. The greater the distance between two genes, the higher the chance that a recombination event will occur between them, and the higher the recombination frequency between them. Two possibilities for recombination between two nonsister chromatids during meiosis are shown in Figure 17.11 . If the recombination frequency between two genes is less than 50 percent, they are said to be linked. The generation of genetic maps requires markers, just as a road map requires landmarks (such as rivers and mountains). Early genetic maps were based on the use of known genes as markers. More sophisticated markers, including those based on non-coding DNA, are now used to compare the genomes of individuals in a population. Although individuals of a given species are genetically similar, they are not identical; every individual has a unique set of traits. These minor differences in the genome between individuals in a population are useful for the purposes of genetic mapping. In general, a good genetic marker is a region on the chromosome that shows variability or polymorphism (multiple forms) in the population. Some genetic markers used in generating genetic maps are restriction fragment length polymorphisms (RFLP), variable number of tandem repeats (VNTRs), microsatellite polymorphisms , and the single nucleotide polymorphisms (SNPs). RFLPs (sometimes pronounced “rif-lips”) are detected when the DNA of an individual is cut with a restriction endonuclease that recognizes specific sequences in the DNA to generate a series of DNA fragments, which are then analyzed by gel electrophoresis. The DNA of every individual will give rise to a unique pattern of bands when cut with a particular set of restriction endonucleases; this is sometimes referred to as an individual’s DNA “fingerprint.” Certain regions of the chromosome that are subject to polymorphism will lead to the generation of the unique banding pattern. VNTRs are repeated sets of nucleotides present in the non-coding regions of DNA. Non-coding, or “junk,” DNA has no known biological function; however, research shows that much of this DNA is actually transcribed. While its function is uncertain, it is certainly active, and it may be involved in the regulation of coding genes. The number of repeats may vary in individual organisms of a population. Microsatellite polymorphisms are similar to VNTRs, but the repeat unit is very small. SNPs are variations in a single nucleotide. Because genetic maps rely completely on the natural process of recombination, mapping is affected by natural increases or decreases in the level of recombination in any given area of the genome. Some parts of the genome are recombination hotspots, whereas others do not show a propensity for recombination. For this reason, it is important to look at mapping information developed by multiple methods. Physical Maps A physical map provides detail of the actual physical distance between genetic markers, as well as the number of nucleotides. There are three methods used to create a physical map: cytogenetic mapping, radiation hybrid mapping, and sequence mapping. Cytogenetic mapping uses information obtained by microscopic analysis of stained sections of the chromosome ( Figure 17.12 ). It is possible to determine the approximate distance between genetic markers using cytogenetic mapping, but not the exact distance (number of base pairs). Radiation hybrid mapping uses radiation, such as x-rays, to break the DNA into fragments. The amount of radiation can be adjusted to create smaller or larger fragments. This technique overcomes the limitation of genetic mapping and is not affected by increased or decreased recombination frequency. Sequence mapping resulted from DNA sequencing technology that allowed for the creation of detailed physical maps with distances measured in terms of the number of base pairs. The creation of genomic libraries and complementary DNA (cDNA) libraries (collections of cloned sequences or all DNA from a genome) has sped up the process of physical mapping. A genetic site used to generate a physical map with sequencing technology (a sequence-tagged site, or STS) is a unique sequence in the genome with a known exact chromosomal location. An expressed sequence tag (EST) and a single sequence length polymorphism (SSLP) are common STSs. An EST is a short STS that is identified with cDNA libraries, while SSLPs are obtained from known genetic markers and provide a link between genetic maps and physical maps. Integration of Genetic and Physical Maps Genetic maps provide the outline and physical maps provide the details. It is easy to understand why both types of genome mapping techniques are important to show the big picture. Information obtained from each technique is used in combination to study the genome. Genomic mapping is being used with different model organisms that are used for research. Genome mapping is still an ongoing process, and as more advanced techniques are developed, more advances are expected. Genome mapping is similar to completing a complicated puzzle using every piece of available data. Mapping information generated in laboratories all over the world is entered into central databases, such as GenBank at the National Center for Biotechnology Information (NCBI). Efforts are being made to make the information more easily accessible to researchers and the general public. Just as we use global positioning systems instead of paper maps to navigate through roadways, NCBI has created a genome viewer tool to simplify the data-mining process. Scientific Method Connection How to Use a Genome Map Viewer Problem statement: Do the human, macaque, and mouse genomes contain common DNA sequences? Develop a hypothesis. To test the hypothesis, click this link . In Search box on the left panel, type any gene name or phenotypic characteristic, such as iris pigmentation (eye color). Select the species you want to study, and then press Enter. The genome map viewer will indicate which chromosome encodes the gene in your search. Click each hit in the genome viewer for more detailed information. This type of search is the most basic use of the genome viewer; it can also be used to compare sequences between species, as well as many other complicated tasks. Is the hypothesis correct? Why or why not? Link to Learning Online Mendelian Inheritance in Man (OMIM) is a searchable online catalog of human genes and genetic disorders. This website shows genome mapping information, and also details the history and research of each trait and disorder. Click this link to search for traits (such as handedness) and genetic disorders (such as diabetes). 17.3 Whole-Genome Sequencing Learning Objectives By the end of this section, you will be able to: Describe three types of sequencing Define whole-genome sequencing Although there have been significant advances in the medical sciences in recent years, doctors are still confounded by some diseases, and they are using whole-genome sequencing to get to the bottom of the problem. Whole-genome sequencing is a process that determines the DNA sequence of an entire genome. Whole-genome sequencing is a brute-force approach to problem solving when there is a genetic basis at the core of a disease. Several laboratories now provide services to sequence, analyze, and interpret entire genomes. For example, whole-exome sequencing is a lower-cost alternative to whole genome sequencing. In exome sequencing, only the coding, exon-producing regions of the DNA are sequenced. In 2010, whole-exome sequencing was used to save a young boy whose intestines had multiple mysterious abscesses. The child had several colon operations with no relief. Finally, whole-exome sequencing was performed, which revealed a defect in a pathway that controls apoptosis (programmed cell death). A bone-marrow transplant was used to overcome this genetic disorder, leading to a cure for the boy. He was the first person to be successfully treated based on a diagnosis made by whole-exome sequencing. Today, human genome sequencing is more readily available and can be completed in a day or two for about $1000. Strategies Used in Sequencing Projects The basic sequencing technique used in all modern day sequencing projects is the chain termination method (also known as the dideoxy method), which was developed by Fred Sanger in the 1970s. The chain termination method involves DNA replication of a single-stranded template with the use of a primer and a regular deoxynucleotide (dNTP), which is a monomer, or a single unit, of DNA. The primer and dNTP are mixed with a small proportion of fluorescently labeled dideoxynucleotides (ddNTPs). The ddNTPs are monomers that are missing a hydroxyl group (–OH) at the site at which another nucleotide usually attaches to form a chain ( Figure 17.13 ). Each ddNTP is labeled with a different color of fluorophore. Every time a ddNTP is incorporated in the growing complementary strand, it terminates the process of DNA replication, which results in multiple short strands of replicated DNA that are each terminated at a different point during replication. When the reaction mixture is processed by gel electrophoresis after being separated into single strands, the multiple newly replicated DNA strands form a ladder because of the differing sizes. Because the ddNTPs are fluorescently labeled, each band on the gel reflects the size of the DNA strand and the ddNTP that terminated the reaction. The different colors of the fluorophore-labeled ddNTPs help identify the ddNTP incorporated at that position. Reading the gel on the basis of the color of each band on the ladder produces the sequence of the template strand ( Figure 17.14 ). Early Strategies: Shotgun Sequencing and Pair-Wise End Sequencing In shotgun sequencing method, several copies of a DNA fragment are cut randomly into many smaller pieces (somewhat like what happens to a round shot cartridge when fired from a shotgun). All of the segments are then sequenced using the chain-sequencing method. Then, with the help of a computer, the fragments are analyzed to see where their sequences overlap. By matching up overlapping sequences at the end of each fragment, the entire DNA sequence can be reformed. A larger sequence that is assembled from overlapping shorter sequences is called a contig . As an analogy, consider that someone has four copies of a landscape photograph that you have never seen before and know nothing about how it should appear. The person then rips up each photograph with their hands, so that different size pieces are present from each copy. The person then mixes all of the pieces together and asks you to reconstruct the photograph. In one of the smaller pieces you see a mountain. In a larger piece, you see that the same mountain is behind a lake. A third fragment shows only the lake, but it reveals that there is a cabin on the shore of the lake. Therefore, from looking at the overlapping information in these three fragments, you know that the picture contains a mountain behind a lake that has a cabin on its shore. This is the principle behind reconstructing entire DNA sequences using shotgun sequencing. Originally, shotgun sequencing only analyzed one end of each fragment for overlaps. This was sufficient for sequencing small genomes. However, the desire to sequence larger genomes, such as that of a human, led to the development of double-barrel shotgun sequencing, more formally known as pairwise-end sequencing . In pairwise-end sequencing, both ends of each fragment are analyzed for overlap. Pairwise-end sequencing is, therefore, more cumbersome than shotgun sequencing, but it is easier to reconstruct the sequence because there is more available information. Next-generation Sequencing Since 2005, automated sequencing techniques used by laboratories are under the umbrella of next-generation sequencing , which is a group of automated techniques used for rapid DNA sequencing. These automated low-cost sequencers can generate sequences of hundreds of thousands or millions of short fragments (25 to 500 base pairs) in the span of one day. These sequencers use sophisticated software to get through the cumbersome process of putting all the fragments in order. Evolution Connection Comparing Sequences A sequence alignment is an arrangement of proteins, DNA, or RNA; it is used to identify regions of similarity between cell types or species, which may indicate conservation of function or structures. Sequence alignments may be used to construct phylogenetic trees. The following website uses a software program called BLAST (basic local alignment search tool) . Under “Basic Blast,” click “Nucleotide Blast.” Input the following sequence into the large "query sequence" box: ATTGCTTCGATTGCA. Below the box, locate the "Species" field and type "human" or "Homo sapiens". Then click “BLAST” to compare the inputted sequence against known sequences of the human genome. The result is that this sequence occurs in over a hundred places in the human genome. Scroll down below the graphic with the horizontal bars and you will see short description of each of the matching hits. Pick one of the hits near the top of the list and click on "Graphics". This will bring you to a page that shows where the sequence is found within the entire human genome. You can move the slider that looks like a green flag back and forth to view the sequences immediately around the selected gene. You can then return to your selected sequence by clicking the "ATG" button. Use of Whole-Genome Sequences of Model Organisms The first genome to be completely sequenced was of a bacterial virus, the bacteriophage fx174 (5368 base pairs); this was accomplished by Fred Sanger using shotgun sequencing. Several other organelle and viral genomes were later sequenced. The first organism whose genome was sequenced was the bacterium Haemophilus influenzae ; this was accomplished by Craig Venter in the 1980s. Approximately 74 different laboratories collaborated on the sequencing of the genome of the yeast Saccharomyces cerevisiae , which began in 1989 and was completed in 1996, because it was 60 times bigger than any other genome that had been sequenced. By 1997, the genome sequences of two important model organisms were available: the bacterium Escherichia coli K12 and the yeast Saccharomyces cerevisiae . Genomes of other model organisms, such as the mouse Mus musculus , the fruit fly Drosophila melanogaster , the nematode Caenorhabditis. elegans , and humans Homo sapiens are now known. A lot of basic research is performed in model organisms because the information can be applied to genetically similar organisms. A model organism is a species that is studied as a model to understand the biological processes in other species represented by the model organism. Having entire genomes sequenced helps with the research efforts in these model organisms. The process of attaching biological information to gene sequences is called genome annotation . Annotation of gene sequences helps with basic experiments in molecular biology, such as designing PCR primers and RNA targets. Link to Learning Click through each step of genome sequencing at this site . Uses of Genome Sequences DNA microarrays are methods used to detect gene expression by analyzing an array of DNA fragments that are fixed to a glass slide or a silicon chip to identify active genes and identify sequences. Almost one million genotypic abnormalities can be discovered using microarrays, whereas whole-genome sequencing can provide information about all six billion base pairs in the human genome. Although the study of medical applications of genome sequencing is interesting, this discipline tends to dwell on abnormal gene function. Knowledge of the entire genome will allow future onset diseases and other genetic disorders to be discovered early, which will allow for more informed decisions to be made about lifestyle, medication, and having children. Genomics is still in its infancy, although someday it may become routine to use whole-genome sequencing to screen every newborn to detect genetic abnormalities. In addition to disease and medicine, genomics can contribute to the development of novel enzymes that convert biomass to biofuel, which results in higher crop and fuel production, and lower cost to the consumer. This knowledge should allow better methods of control over the microbes that are used in the production of biofuels. Genomics could also improve the methods used to monitor the impact of pollutants on ecosystems and help clean up environmental contaminants. Genomics has allowed for the development of agrochemicals and pharmaceuticals that could benefit medical science and agriculture. It sounds great to have all the knowledge we can get from whole-genome sequencing; however, humans have a responsibility to use this knowledge wisely. Otherwise, it could be easy to misuse the power of such knowledge, leading to discrimination based on a person's genetics, human genetic engineering, and other ethical concerns. This information could also lead to legal issues regarding health and privacy. 17.4 Applying Genomics Learning Objectives By the end of this section, you will be able to: Explain pharmacogenomics Define polygenic The introduction of DNA sequencing and whole genome sequencing projects, particularly the Human Genome project, has expanded the applicability of DNA sequence information. Genomics is now being used in a wide variety of fields, such as metagenomics, pharmacogenomics, and mitochondrial genomics. The most commonly known application of genomics is to understand and find cures for diseases. Predicting Disease Risk at the Individual Level Predicting the risk of disease involves screening currently healthy individuals by genome analysis at the individual level. Intervention with lifestyle changes and drugs can be recommended before disease onset. However, this approach is most applicable when the problem resides within a single gene defect. Such defects only account for approximately 5 percent of diseases in developed countries. Most of the common diseases, such as heart disease, are multi-factored or polygenic , which is a phenotypic characteristic that involves two or more genes, and also involve environmental factors such as diet. In April 2010, scientists at Stanford University published the genome analysis of a healthy individual (Stephen Quake, a scientist at Stanford University, who had his genome sequenced); the analysis predicted his propensity to acquire various diseases. A risk assessment was performed to analyze Quake’s percentage of risk for 55 different medical conditions. A rare genetic mutation was found, which showed him to be at risk for sudden heart attack. He was also predicted to have a 23 percent risk of developing prostate cancer and a 1.4 percent risk of developing Alzheimer’s. The scientists used databases and several publications to analyze the genomic data. Even though genomic sequencing is becoming more affordable and analytical tools are becoming more reliable, ethical issues surrounding genomic analysis at a population level remain to be addressed. Visual Connection In 2011, the United States Preventative Services Task Force recommended against using the PSA test to screen healthy men for prostate cancer. Their recommendation is based on evidence that screening does not reduce the risk of death from prostate cancer. Prostate cancer often develops very slowly and does not cause problems, while the cancer treatment can have severe side effects. The PCA3 test is considered to be more accurate, but screening may still result in men who would not have been harmed by the cancer itself suffering side effects from treatment. What do you think? Should all healthy men be screened for prostate cancer using the PCA3 or PSA test? Should people in general be screened to find out if they have a genetic risk for cancer or other diseases? Pharmacogenomics and Toxicogenomics Pharmacogenomics , also called toxicogenomics, involves evaluating the effectiveness and safety of drugs on the basis of information from an individual's genomic sequence. Genomic responses to drugs can be studied using experimental animals (such as laboratory rats or mice) or live cells in the laboratory before embarking on studies with humans. Studying changes in gene expression could provide information about the transcription profile in the presence of the drug, which can be used as an early indicator of the potential for toxic effects. For example, genes involved in cellular growth and controlled cell death, when disturbed, could lead to the growth of cancerous cells. Genome-wide studies can also help to find new genes involved in drug toxicity. Personal genome sequence information can be used to prescribe medications that will be most effective and least toxic on the basis of the individual patient’s genotype. The gene signatures may not be completely accurate, but can be tested further before pathologic symptoms arise. Microbial Genomics: Metagenomics Traditionally, microbiology has been taught with the view that microorganisms are best studied under pure culture conditions, which involves isolating a single type of cell and culturing it in the laboratory. Because microorganisms can go through several generations in a matter of hours, their gene expression profiles adapt to the new laboratory environment very quickly. In addition, the vast majority of bacterial species resist being cultured in isolation. Most microorganisms do not live as isolated entities, but in microbial communities known as biofilms. For all of these reasons, pure culture is not always the best way to study microorganisms. Metagenomics is the study of the collective genomes of multiple species that grow and interact in an environmental niche. Metagenomics can be used to identify new species more rapidly and to analyze the effect of pollutants on the environment ( Figure 17.16 ). Microbial Genomics: Creation of New Biofuels Knowledge of the genomics of microorganisms is being used to find better ways to harness biofuels from algae and cyanobacteria. The primary sources of fuel today are coal, oil, wood, and other plant products, such as ethanol. Although plants are renewable resources, there is still a need to find more alternative renewable sources of energy to meet our population’s energy demands. The microbial world is one of the largest resources for genes that encode new enzymes and produce new organic compounds, and it remains largely untapped. Microorganisms are used to create products, such as enzymes that are used in research, antibiotics, and other anti-microbial mechanisms. Microbial genomics is helping to develop diagnostic tools, improved vaccines, new disease treatments, and advanced environmental cleanup techniques. Mitochondrial Genomics Mitochondria are intracellular organelles that contain their own DNA. Mitochondrial DNA mutates at a rapid rate and is often used to study evolutionary relationships. Another feature that makes studying the mitochondrial genome interesting is that the mitochondrial DNA in most multicellular organisms is passed on from the mother during the process of fertilization. For this reason, mitochondrial genomics is often used to trace genealogy. Information and clues obtained from DNA samples found at crime scenes have been used as evidence in court cases, and genetic markers have been used in forensic analysis. Genomic analysis has also become useful in this field. In 2001, the first use of genomics in forensics was published. It was a collaborative attempt between academic research institutions and the FBI to solve the mysterious cases of anthrax communicated via the US Postal Service. Using microbial genomics, researchers determined that a specific strain of anthrax was used in all the mailings. Genomics in Agriculture Genomics can reduce the trials and failures involved in scientific research to a certain extent, which could improve the quality and quantity of crop yields in agriculture. Linking traits to genes or gene signatures helps to improve crop breeding to generate hybrids with the most desirable qualities. Scientists use genomic data to identify desirable traits, and then transfer those traits to a different organism. Scientists are discovering how genomics can improve the quality and quantity of agricultural production. For example, scientists could use desirable traits to create a useful product or enhance an existing product, such as making a drought-sensitive crop more tolerant of the dry season. 17.5 Genomics and Proteomics Learning Objectives By the end of this section, you will be able to: Explain systems biology Describe a proteome Define protein signature Proteins are the final products of genes, which help perform the function encoded by the gene. Proteins are composed of amino acids and play important roles in the cell. All enzymes (except ribozymes) are proteins that act as catalysts to affect the rate of reactions. Proteins are also regulatory molecules, and some are hormones. Transport proteins, such as hemoglobin, help transport oxygen to various organs. Antibodies that defend against foreign particles are also proteins. In the diseased state, protein function can be impaired because of changes at the genetic level or because of direct impact on a specific protein. A proteome is the entire set of proteins produced by a cell type. Proteomes can be studied using the knowledge of genomes because genes code for mRNAs, and the mRNAs encode proteins. Although mRNA analysis is a step in the right direction, not all mRNAs are translated into proteins. The study of the function of proteomes is called proteomics . Proteomics complements genomics and is useful when scientists want to test their hypotheses that were based on genes. Even though all cells of a multicellular organism have the same set of genes, the set of proteins produced in different tissues is different and dependent on gene expression. Thus, the genome is constant, but the proteome varies and is dynamic within an organism. In addition, RNAs can be alternately spliced (cut and pasted to create novel combinations and novel proteins) and many proteins are modified after translation by processes such as proteolytic cleavage, phosphorylation, glycosylation, and ubiquitination. There are also protein-protein interactions, which complicate the study of proteomes. Although the genome provides a blueprint, the final architecture depends on several factors that can change the progression of events that generate the proteome. Metabolomics is related to genomics and proteomics. Metabolomics involves the study of small molecule metabolites found in an organism. The metabolome is the complete set of metabolites that are related to the genetic makeup of an organism. Metabolomics offers an opportunity to compare genetic makeup and physical characteristics, as well as genetic makeup and environmental factors. The goal of metabolome research is to identify, quantify, and catalogue all of the metabolites that are found in the tissues and fluids of living organisms. Basic Techniques in Protein Analysis The ultimate goal of proteomics is to identify or compare the proteins expressed from a given genome under specific conditions, study the interactions between the proteins, and use the information to predict cell behavior or develop drug targets. Just as the genome is analyzed using the basic technique of DNA sequencing, proteomics requires techniques for protein analysis. The basic technique for protein analysis, analogous to DNA sequencing, is mass spectrometry. Mass spectrometry is used to identify and determine the characteristics of a molecule. Advances in spectrometry have allowed researchers to analyze very small samples of protein. X-ray crystallography, for example, enables scientists to determine the three-dimensional structure of a protein crystal at atomic resolution. Another protein imaging technique, nuclear magnetic resonance (NMR), uses the magnetic properties of atoms to determine the three-dimensional structure of proteins in aqueous solution. Protein microarrays have also been used to study interactions between proteins. Large-scale adaptations of the basic two-hybrid screen ( Figure 17.17 ) have provided the basis for protein microarrays. Computer software is used to analyze the vast amount of data generated for proteomic analysis. Genomic- and proteomic-scale analyses are part of systems biology. Systems biology is the study of whole biological systems (genomes and proteomes) based on interactions within the system. The European Bioinformatics Institute and the Human Proteome Organization (HUPO) are developing and establishing effective tools to sort through the enormous pile of systems biology data. Because proteins are the direct products of genes and reflect activity at the genomic level, it is natural to use proteomes to compare the protein profiles of different cells to identify proteins and genes involved in disease processes. Most pharmaceutical drug trials target proteins. Information obtained from proteomics is being used to identify novel drugs and understand their mechanisms of action. The challenge of techniques used for proteomic analyses is the difficulty in detecting small quantities of proteins. Although mass spectrometry is good for detecting small amounts of proteins, variations in protein expression in diseased states can be difficult to discern. Proteins are naturally unstable molecules, which makes proteomic analysis much more difficult than genomic analysis. Cancer Proteomics Genomes and proteomes of patients suffering from specific diseases are being studied to understand the genetic basis of the disease. The most prominent disease being studied with proteomic approaches is cancer. Proteomic approaches are being used to improve screening and early detection of cancer; this is achieved by identifying proteins whose expression is affected by the disease process. An individual protein is called a biomarker , whereas a set of proteins with altered expression levels is called a protein signature . For a biomarker or protein signature to be useful as a candidate for early screening and detection of a cancer, it must be secreted in body fluids, such as sweat, blood, or urine, such that large-scale screenings can be performed in a non-invasive fashion. The current problem with using biomarkers for the early detection of cancer is the high rate of false-negative results. A false negative is an incorrect test result that should have been positive. In other words, many cases of cancer go undetected, which makes biomarkers unreliable. Some examples of protein biomarkers used in cancer detection are CA-125 for ovarian cancer and PSA for prostate cancer. Protein signatures may be more reliable than biomarkers to detect cancer cells. Proteomics is also being used to develop individualized treatment plans, which involves the prediction of whether or not an individual will respond to specific drugs and the side effects that the individual may experience. Proteomics is also being used to predict the possibility of disease recurrence. The National Cancer Institute has developed programs to improve the detection and treatment of cancer. The Clinical Proteomic Technologies for Cancer and the Early Detection Research Network are efforts to identify protein signatures specific to different types of cancers. The Biomedical Proteomics Program is designed to identify protein signatures and design effective therapies for cancer patients.
business_ethics
Summary 10.1 More Telecommuting or Less? Remote workers save themselves the time and cost of a commute and are better able to balance work and home life. Companies often benefit from the higher productivity and lower turnover of telecommuting employees, and they can also provide a social benefit by permitting employees to avoid commuting, reducing traffic congestion and pollution. Some challenges of telecommuting for the manager are maintaining the privacy of the firm’s data, transmitting corporate culture, defining performance objectives, and encouraging collaboration. Employees have the challenge of remaining focused on work when they are working elsewhere. Ethical companies support their remote workers by developing and encouraging trust and guarding against abuse. They also set clear and equitable expectations and rewards to ensure fairness and keep open the lines of communication. 10.2 Workplace Campuses Traditional office buildings with separate workspaces for each worker are giving way to multifunctional worksites where employees are encouraged to actively collaborate. Some companies have expanded the workplace to include restaurants, recreation facilities, and convenient amenities to attract and retain employees. Other companies are building villages around their campuses to assist employees seeking to balance work and home life. These all-encompassing work environments have some potential downsides for employees, however, including a risk of tethering them to their workplaces. Their effects on local communities are being questioned as well. 10.3 Alternatives to Traditional Patterns of Work When undertaken with equity and fairness, job sharing and flextime can create flexibility for workers who need or want to limit their hours. These practices allow employers to recruit more diverse employees, help them meet employees’ need for work-life balance, and, in the case of job sharing, bring more than one person’s perspective to problem solving. However, employers must clearly spell out expectations and procedures for each employee to ensure success. Given flexible hours and job-sharing arrangements, the traditional employment-based U.S. economy appears to be in transition toward new business models that offer many opportunities but also serious challenges. Ethical issues in the access economy include the responsibilities of each of the parties in a sharing transaction and the character of any regulation, including taxes, that may be passed. In the gig economy, they include workers’ insecure positions and lack of benefits, employers’ responsibility for paying their fair share of social insurance (payroll) taxes, and the fair treatment of interns. 10.4 Robotics, Artificial Intelligence, and the Workplace of the Future Initially, robots and AI inspire both intrigue and fear in most of us. Fear of losing jobs is a reality, but so too is intrigue about what the future holds. A key for companies is to help workers retrain to become part of that future.
Chapter Outline 10.1 More Telecommuting or Less? 10.2 Workplace Campuses 10.3 Alternatives to Traditional Patterns of Work 10.4 Robotics, Artificial Intelligence, and the Workplace of the Future Introduction Beginning in the eighteenth century, in much of the Western world, the Industrial Revolution transformed the nature of work as industry displaced agriculture as the main driver of the economy and machines took over manual labor. Continuing technological changes have further altered the way people work and even the time and place where they do so. Growing numbers of people now spend some of their time working at home. Are they more productive without the distractions of the office or less productive without constant monitoring by managers? Some major companies like Apple, Amazon, Facebook, and Microsoft have constructed elaborate workplace campuses, offering unprecedented levels of amenities and even employee housing. Do these campuses facilitate the balancing of work and life, or do they blur the distinction and tie workers to their jobs instead? Job sharing and flexible work schedules have emerged as alternatives to traditional patterns of work. These practices permit some workers to more easily fulfill work and life responsibilities. But does job sharing reflect employers’ efforts to respond to workers’ preferences or is it a move to reduce costs? How will you prepare employees for the impact of robots at work ( Figure 10.1 ) or manage the outsourcing of tasks to contractors in the gig economy? These challenges to traditional employment settings carry ethical implications for all stakeholders, including employers, employees, suppliers, customers, and clients.
[ { "answer": { "ans_choice": 1, "ans_text": "B" }, "bloom": null, "hl_context": "<hl> More broadly , there is a good deal of evidence suggesting that telecommuting has beneficial effects on worker productivity . <hl> <hl> For example , a call-center study reported in the Harvard Business Review found that telecommuting employees made 13.5 percent more calls , resigned their positions at only half the usual rate , and had much higher job satisfaction compared with employees who did not telecommute . <hl> 7 The Colorado Department of Transportation , in a study of telecommuting productivity for a branch that issued permits , found 48 percent faster turnaround times for issuing permits and 5 percent more calls for telecommuters . 8 Furthermore , studies of JD Edwards teleworkers found them to be 20 to 25 percent more productive than their office colleagues ; American Express employees who worked from home were 43 percent more productive than workers in the office . 9 With none of the distractions of a traditional office setting , like water-cooler gossip and long lunches , and with the happier attitude , workers tend to enjoy when they have control over their work lives . <hl> Telecommuting facilitates increased efficiency and productivity and also typically results in higher retention of workers , thereby reducing recruiting and training costs for firms . <hl>", "hl_sentences": "More broadly , there is a good deal of evidence suggesting that telecommuting has beneficial effects on worker productivity . For example , a call-center study reported in the Harvard Business Review found that telecommuting employees made 13.5 percent more calls , resigned their positions at only half the usual rate , and had much higher job satisfaction compared with employees who did not telecommute . Telecommuting facilitates increased efficiency and productivity and also typically results in higher retention of workers , thereby reducing recruiting and training costs for firms .", "question": { "cloze_format": "___ is not a prospective benefit to the firm of implementing a telecommuting program.", "normal_format": "Which of the following is not a prospective benefit to the firm of implementing a telecommuting program?", "question_choices": [ "higher productivity of telecommuting workers", "greater connectivity and collaboration among employees", "lower operating costs", "more satisfied workers" ], "question_id": "fs-idm229464816", "question_text": "Which of the following is not a prospective benefit to the firm of implementing a telecommuting program?" }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 0, "ans_text": "A" }, "bloom": null, "hl_context": "It would be unethical to place workers without assistance in a new situation in which they can easily fail . <hl> Telecommuting workers must be trained in time-management skills so they can maintain their productivity in an environment that may have more or different distractions than a traditional workplace and may make different demands on their time . <hl> <hl> Training should also strengthen communication skills , such as responding to messages promptly , that help ensure success in a remote setting . <hl> <hl> To help guard against the risk that telecommuting employees will be unfairly considered “ out of sight , out of mind , ” the ethical company will adopt written expectations about timely communication in both directions . <hl> For instance , it should ensure that managers ’ lines of communication are as open to their remote employees as they are to those who can drop by their desk or office to chat .", "hl_sentences": "Telecommuting workers must be trained in time-management skills so they can maintain their productivity in an environment that may have more or different distractions than a traditional workplace and may make different demands on their time . Training should also strengthen communication skills , such as responding to messages promptly , that help ensure success in a remote setting . To help guard against the risk that telecommuting employees will be unfairly considered “ out of sight , out of mind , ” the ethical company will adopt written expectations about timely communication in both directions .", "question": { "cloze_format": "A successful telecommuting program would include ___.", "normal_format": "A successful telecommuting program would include which of the following?", "question_choices": [ "a written policy that spells out expectations", "an oral policy the manager can change at will", "subjective criteria for each individual worker", "preference for some people to telecommute over others" ], "question_id": "fs-idm226493952", "question_text": "A successful telecommuting program would include which of the following?" }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 2, "ans_text": "C" }, "bloom": null, "hl_context": "The remote worker may have qualms about privacy when his or her personal life inevitably intersects with the workday ( as when a family member walks into the room or the dog barks during a conference call ) . 23 Children may be confused when it seems like their parent is home but is not available for meals or play or homework help . <hl> It may be difficult for remote workers to maintain a work-life balance when their home becomes their office ( especially if their hours are flexible ) . <hl> Workers may have to set aside living space for a home office and spend money to buy computing equipment , a desk , and other supplies .", "hl_sentences": "It may be difficult for remote workers to maintain a work-life balance when their home becomes their office ( especially if their hours are flexible ) .", "question": { "cloze_format": "When considering the issue of work-life balance, the point that ___ does not apply.", "normal_format": "When considering the issue of work-life balance, which of the following points does not apply?", "question_choices": [ "Each employee probably assesses this differently.", "Managers and workers as cohorts often have different perspectives on it.", "Workers with families at home should be entitled to a “better” balance.", "All employees have a right to pursue this." ], "question_id": "fs-idm229191040", "question_text": "When considering the issue of work-life balance, which of the following points does not apply?" }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 0, "ans_text": "A" }, "bloom": null, "hl_context": "<hl> According to global consulting giant Accenture , AI is “ a collection of advanced technologies that allows machines to sense , comprehend , act and learn . ” Accenture contends that AI will be the next great advance in the workplace : “ It is set to transform business in ways we have not seen since the Industrial Revolution ; fundamentally reinventing how businesses run , compete and thrive . <hl> <hl> When implemented holistically , these technologies help improve productivity and lower costs , unlocking more creative jobs and creating new growth opportunities . ” 76 Accenture looked at twelve of the world ’ s most developed countries , which account for more than half of world economic output , to assess the impact of AI in sixteen specific industries . <hl> According to its report , AI has the potential to significantly increase corporate profitability , double rates of economic growth by 2035 , increase labor productivity by as much as 40 percent , and boost gross value added by $ 14 trillion by 2035 , based on an almost 40 percent increase in rates of return . 77 Even news articles have begun to be written by robots . 78 It is hard to imagine that anyone could find fault with a job that came with all the amenities of a campus-like environment . However , the all-encompassing aspect of these workplaces means a manager ’ s job description greatly expands to include small-city management functions . <hl> As the April 2018 shooting of employees at YouTube ’ s headquarters suggests , corporate campuses may have a greater need for security , with duties that dovetail those of the city police . <hl> <hl> Growth of the compound will challenge managers to comply with city planning and zoning regulations . <hl> <hl> How should these villages within a city contribute to the municipal services they need for the population they draw ? <hl> <hl> Should the city be able to require a greater tax contribution from mega-corporate campus developers that equals the load they add to the city ’ s fiscal responsibilities ? <hl> Have employers then crossed a line with these perks ? Have they created an expectation that the employee who works on a corporate campus where all needed services are provided will , in turn , be accessible for long hours of work on a regular basis ? Are the amenities really velvet handcuffs that tie employees to work ? Living right next to work clearly will reduce commuting time , and via this path , it may promote work-life balance . But the expectation that long hours should be routine just because they are possible will hamper , rather than facilitate , the quest for work-life balance . <hl> Furthermore , to the extent that mega-corporate campuses do tie workers to their jobs , reduced worker mobility means that labor markets will be less able to adjust to changing conditions . <hl>", "hl_sentences": "According to global consulting giant Accenture , AI is “ a collection of advanced technologies that allows machines to sense , comprehend , act and learn . ” Accenture contends that AI will be the next great advance in the workplace : “ It is set to transform business in ways we have not seen since the Industrial Revolution ; fundamentally reinventing how businesses run , compete and thrive . When implemented holistically , these technologies help improve productivity and lower costs , unlocking more creative jobs and creating new growth opportunities . ” 76 Accenture looked at twelve of the world ’ s most developed countries , which account for more than half of world economic output , to assess the impact of AI in sixteen specific industries . As the April 2018 shooting of employees at YouTube ’ s headquarters suggests , corporate campuses may have a greater need for security , with duties that dovetail those of the city police . Growth of the compound will challenge managers to comply with city planning and zoning regulations . How should these villages within a city contribute to the municipal services they need for the population they draw ? Should the city be able to require a greater tax contribution from mega-corporate campus developers that equals the load they add to the city ’ s fiscal responsibilities ? Furthermore , to the extent that mega-corporate campuses do tie workers to their jobs , reduced worker mobility means that labor markets will be less able to adjust to changing conditions .", "question": { "cloze_format": "___ is not a potential downside of a corporate campus.", "normal_format": "Which of the following is not a potential downside of a corporate campus?", "question_choices": [ "Impaired productivity", "Reduced ability of labor markets to adjust to changing conditions", "Adverse impact on local businesses", "Increased fiscal burden on local government" ], "question_id": "fs-idm229855776", "question_text": "Which of the following is not a potential downside of a corporate campus?" }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 3, "ans_text": "D" }, "bloom": null, "hl_context": "Flextime was a starting place for creative new approaches to work . Teams now trade shifts to accommodate members ’ needs for time off . <hl> Some companies allow a compressed work week that caters to the efficient employee who can get a week ’ s work done in less than forty hours . <hl> In some professions , such as accounting , employees might be allowed a reduced schedule during the off season . 58", "hl_sentences": "Some companies allow a compressed work week that caters to the efficient employee who can get a week ’ s work done in less than forty hours .", "question": { "cloze_format": "Some employers allow workers a compressed work week as long as ________.", "normal_format": "Some employers allow workers a compressed work week as long as what condition is met?", "question_choices": [ "the work can be put off until the next week", "the workplace is a store", "it is a week in which a holiday falls on Monday", "the employee can completely finish the work in a shorter time" ], "question_id": "fs-idm207406400", "question_text": "Some employers allow workers a compressed work week as long as ________." }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 0, "ans_text": "A" }, "bloom": null, "hl_context": "In the laboratory at the University of Tokyo School of Engineering , advances are also being made in technology that mimics the capabilities of the human eye . <hl> One application allows scientists a clear field of vision in extreme weather conditions that are otherwise difficult or impossible for humans to study . <hl> <hl> New uses of robots include hazardous cleanup in the wake of the 2011 earthquake and tsunami disaster that destroyed the Fukushima Daiichi nuclear power plant . <hl> After those events , Japan accelerated its development and application of disaster-response robots to go into radioactive areas and handle remediation . In developing countries , the report predicts that the number of jobs requiring less education will shrink . <hl> Furthermore , robotics will have less impact in poorer countries because these nations ’ workers are already paid so little that employers will save less on labor costs by automating . <hl> According to the report , for example , by the same date of 2030 , India is expected to lose only about 9 percent of its jobs to emerging technology . <hl> A McKinsey Global Institute study of eight hundred occupations in nearly fifty countries showed that more than 800 million jobs , or 20 percent of the global workforce , could be lost to robotics by the year 2030 . <hl> 74 The effects could be even more pronounced in wealthy industrialized nations , such as the United States and Germany , where researchers expect that up to one-third of the workforce will be affected . By 2030 , the report estimates that 39 million to 73 million jobs may be eliminated in the United States . Given that the level of employment in the United States in mid - 2018 is approaching 150 million workers , this potential loss of jobs represents roughly one-quarter to one-half of total current employment ( but a smaller share of employment in 2030 because of future population and employment growth ) . Advances in the field of robotics — a combination of computer science , mechanical and electronics engineering , and science — have meant that machines or related forms of automation now do the work of humans in a wide variety of settings , such as medicine , where robots perform surgeries previously done by the surgeon ’ s hand . Robots have made it easier and cheaper for employers to get work done . <hl> The downside , however , is that some reasonably well-paying jobs that provided middle-class employment for humans have become the province of machines . <hl>", "hl_sentences": "One application allows scientists a clear field of vision in extreme weather conditions that are otherwise difficult or impossible for humans to study . New uses of robots include hazardous cleanup in the wake of the 2011 earthquake and tsunami disaster that destroyed the Fukushima Daiichi nuclear power plant . Furthermore , robotics will have less impact in poorer countries because these nations ’ workers are already paid so little that employers will save less on labor costs by automating . A McKinsey Global Institute study of eight hundred occupations in nearly fifty countries showed that more than 800 million jobs , or 20 percent of the global workforce , could be lost to robotics by the year 2030 . The downside , however , is that some reasonably well-paying jobs that provided middle-class employment for humans have become the province of machines .", "question": { "cloze_format": "The use of robots at work ________.", "normal_format": "Which of the following is correct about the use of robots at work?", "question_choices": [ "can reduce the exposure of humans to dangerous working conditions", "costs more than human labor", "must first be approved by the Occupational Safety and Health Administration", "is unlikely to affect the number of people in the overall workforce" ], "question_id": "fs-idm336749184", "question_text": "The use of robots at work ________." }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 3, "ans_text": "D" }, "bloom": null, "hl_context": "A report by KPMG , another global consulting and accounting firm , indicates that almost 50 percent of the activities people perform in the workplace today could be automated , most often by using AI and automation technology that already exist . <hl> The ethical question facing the business community , and all of us on a broader level , is about the type of society in which we all want to live and the role automation will play in it . <hl> <hl> The answer is not simply about efficiency ; a company should consider many variables as it moves toward increased automation ( Figure 10.9 ) . <hl>", "hl_sentences": "The ethical question facing the business community , and all of us on a broader level , is about the type of society in which we all want to live and the role automation will play in it . The answer is not simply about efficiency ; a company should consider many variables as it moves toward increased automation ( Figure 10.9 ) .", "question": { "cloze_format": "Worker retraining programs for employees who lose their jobs to robots ________.", "normal_format": "Which of the following is correct about worker retraining programs for employees who lose their jobs to robots?", "question_choices": [ "are a “Band-Aid” solution most of the time", "will be needed only for a small minority of the workers who lose their jobs", "are offered and funded by the employers only if a sufficient number of workers are displaced", "are an obligation taken on by ethical companies" ], "question_id": "fs-idm371003920", "question_text": "Worker retraining programs for employees who lose their jobs to robots ________." }, "references_are_paraphrase": 0 } ]
10
10.1 More Telecommuting or Less? Learning Objectives By the end of this section, you will be able to: Identify the benefits of permitting employees to work from home Explain the drawbacks of telecommuting for the business and for employees Discuss the ethical dilemmas related to telecommuting and some of the solutions What if your business wanted to expand its local operations from six employees to ten but did not have the office space to add more workers? Today’s businesses have a toolkit of technical solutions to set up working relationships with employees far and wide through voice, computer, video connections, and offsite work-sharing spaces. Coworkers can share files on a remote network server or on the cloud, and managers can use nontraditional methods to monitor activity and performance. Companies like General Assembly, WeWork, and Workbar are leasing access to communal spaces equipped for the business needs of remote workers. Telecommuting is therefore easier to implement than ever. But what exactly are the benefits and drawbacks of telecommuting, and what ethical issues does it raise? Telecommuting and Its Advantages The term telecommuting emerged in the 1970s to describe the practice of working at a specific location, whether the employee’s home or an alternate office, to reduce commuting time to a centrally located office space or store. “Telework” was greatly facilitated by new telecommunications technology, including the Internet, e-mail, and mobile phones. Today, telecommuting means any mode of working at a remote location (home or other space) by virtue of an electronic connection and/or telephone and encompasses a variety of employment types, from gig assignments to part-time contract work to traditional full-time employment. The most recent Census data reveal that almost four million U.S. employees skip the commute for at least part of each week, and according to a 2012 poll, worldwide, one in five workers telecommutes frequently, with approximately 10 percent working from home every day. 1 Figure 10.2 depicts the growth in telecommuting in the United States, China, India, France, Germany, and the United Kingdom. Clearly, employers are embracing telecommuting as a tool for flexibility, on a scale from occasional use to full-time implementation. 2 Employees can connect to networked company computers from home and use work-enhancing tools on their laptops, tablets, and smartphones to make real-time connections by voice, text, or video with inexpensive or free applications (or “apps”) like FaceTime and Skype. Other software solutions, like GoToMeeting or WebEx, make setting up and even recording a synchronous meeting with sound and video possible for even the smallest companies at fairly low cost. The communication and productivity tools that facilitate telecommuting can only grow in number and sophistication. Virtual reality tools like Microsoft’s Mixed Reality allow a worker in one location to communicate with the holograph of another person in real time. For example, this technology could enable a job interview with a remote candidate. Of course, the use of technology brings with it the need to ensure information security and protection against hacking, including guaranteeing the authenticity of the persons engaging via this technology. Employers allow employees to telecommute for a variety of reasons. First, it is a powerful recruiting tool for people who want to balance their work and personal lives. It allows employees to work a more flexible schedule to care for children or older relatives while maintaining a career and earning income. 3 Individuals with ability challenges also prefer the flexibility that telecommuting affords them. 4 Telecommuting also reduces the hours that employees spend traveling to and from the job and can help keep cars off the road. Fewer workers commuting equals less crowding on public transportation. 5 Fewer cars mean less air pollution as well. The average U.S. employee (who commutes 30 miles and 60 minutes per day) will save more than $1000 on gas per year by telecommuting (along with associated costs of parking and vehicle upkeep and insurance). 6 Remote workers can continue to do their jobs despite weather conditions that impede travel. They are not exposed to sick coworkers’ germs and may take fewer sick days (which sometimes translates to fewer sick days company-wide). Remote employees are also seldom late for work or early to leave when their workday starts at home. More broadly, there is a good deal of evidence suggesting that telecommuting has beneficial effects on worker productivity. For example, a call-center study reported in the Harvard Business Review found that telecommuting employees made 13.5 percent more calls, resigned their positions at only half the usual rate, and had much higher job satisfaction compared with employees who did not telecommute. 7 The Colorado Department of Transportation, in a study of telecommuting productivity for a branch that issued permits, found 48 percent faster turnaround times for issuing permits and 5 percent more calls for telecommuters. 8 Furthermore, studies of JD Edwards teleworkers found them to be 20 to 25 percent more productive than their office colleagues; American Express employees who worked from home were 43 percent more productive than workers in the office. 9 With none of the distractions of a traditional office setting, like water-cooler gossip and long lunches, and with the happier attitude, workers tend to enjoy when they have control over their work lives. Telecommuting facilitates increased efficiency and productivity and also typically results in higher retention of workers, thereby reducing recruiting and training costs for firms. Studies have shown that a person who commutes for an hour a day experiences added stress, anxiety, social isolation, and possibly depression. 10 Perhaps that is why companies that implement telecommuting experience less absenteeism overall. 11 It may also be easier to collaborate when not sharing a limited amount of space (such as in a cubicle forest), and people may be more willing to share resources with one another when the total number of workers present at the facility is reduced. Another point is that there may be less chatting and gossip among remote workers who are not in daily contact with each other or their colleagues. Employers may be attracted to telecommuting for other reasons. Having remote employees can reduce office-space costs. 12 In fact, a company can consider expanding even when there is no available real estate or capital to enlarge or improve the physical facilities. Companies that hire remote employees can also widen their pool of potential applicants. 13 They can choose recruits with better job skills than the local population could provide and expand their sales and marketing territory by hiring employees based in a new area. Finally, there are many external environmental benefits of telecommuting. We have seen that a business that reduces total office space also reduces its impact on the environment. 14 Remote workers would increase their individual consumption of utilities while working at home, but chances are that their home’s energy consumption partially continues during the time spent at a traditional job as well ( Figure 10.3 ). The Drawbacks of Telecommuting In 2013, Yahoo’s then–chief executive officer (CEO), Marissa Mayer, ended the company’s work-at-home policy, contending that the change would boost communication and collaboration by bringing people back to the office to work with their colleagues face to face. 15 IBM, Aetna, and Bank of America followed her lead, citing a greater need for collaborative communication to compete with smaller firms. 16 A backlash in the media followed this announcement, because working at home is popular among Yahoo employees. Yahoo has since shown greater flexibility in allowing some employees to once again work at home. 17 But recent research does reveal that employees collaborate more creatively when they meet to discuss projects face to face. This finding has important implications for firms dependent on research and development for their future growth. In fact, Steve Jobs designed the Pixar facility to increase the likelihood of conversations that would promote idea generation. 18 Corporate culture is not easy to convey over distance. The remote worker might have developed certain working habits at a different company with a different corporate culture (sometimes in another country). It can be challenging to help employees adapt to the culture of a new company when they work remotely. 19 It is also more difficult for employers to monitor some kinds of work-related progress when an employee is working remotely. The likelihood of miscommunication increases when everything must be transmitted electronically or virtually. 20 A manager cannot “manage by walking around” when the worker is remote. There are no incidental opportunities to witness a worker interacting with a client or customer. 21 Workers may also be more hesitant to ask for direction on a project. Some managers worry that employees will slack off if there is no one there to watch them. 22 The remote worker may have qualms about privacy when his or her personal life inevitably intersects with the workday (as when a family member walks into the room or the dog barks during a conference call). 23 Children may be confused when it seems like their parent is home but is not available for meals or play or homework help. It may be difficult for remote workers to maintain a work-life balance when their home becomes their office (especially if their hours are flexible). Workers may have to set aside living space for a home office and spend money to buy computing equipment, a desk, and other supplies. Furthermore, it is difficult for an on-site technology team to provide technical assistance or secure data at the level the company may require when people are working at home. Moreover, when the definition of the workplace begins to blur, who is responsible for injuries that occur on the job at home? The employer is unable to exercise the same control over safety measures that holds in a traditional workplace. 24 There may also be productivity concerns. Some remote workers will rise to the challenge of motivating themselves to work diligently. In fact, studies have shown that some remote workers are more productive than their traditional counterparts. 25 But it is not easy to sort potential employees into workers and procrastinators without some period of trial and error, which may be costly. Not all fields are equally suited to telecommuting. Some jobs require consistent in-person contact with clients or customers, such as counseling, physical therapy, and medicine. 26 Some industries need the highest computer security, such as banking and finance. Other work settings, such as law enforcement, have increased needs for building security that would make working remotely an unsafe alternative for employees. 27 The biggest drawback of telecommuting for the individual employee is the bias that studies reveal in employer attitudes. Most managers, after all, attained their status in a traditional job. When some employees telecommute and others do not, those who are in the physical presence of the employer every day can more easily make an impression (good or bad) simply by interacting with their manager. There is also some indication that employees who opt for a nontraditional work arrangement may be penalized if they are perceived as lazy or less dedicated than those who maintain traditional work hours. Employers might have a stronger recollection of the work produced by the employee they see regularly than they do of the work a remote employee is submitting online. Therefore, promotions and important projects may go to employees who are more visible. The remote employee might eventually be left without equal footing in the push for increased pay and status. The Ethical Challenges of Telecommuting Ethical employers must juggle the potential ethical challenges of managing remote employees, including developing trust in remote workers, encouraging trust among project team members when some are working remotely, keeping equity in mind when reviewing the performance of remote and in-office staff, and deciding which employees get to work remotely. Supervisors also must guard against abuse of the remote-work opportunity, maintain the security of the remote employee’s work-related data, foster a level of collaboration that is vital to product development, and protect the remote worker’s safety. 28 How can managers meet these challenges? Although it is easy to consider allowing telecommuting for those who simply ask, managers should instead categorize jobs (not people) by their suitability for remote work. Best Buy recently announced it would modify its work-from-home policy for employees in its corporate office, changing it from a perquisite (or “perk”) of employment to one granted by management on a case-by-case basis and mindful of the circumstances of individual workers. 29 Managers should also carefully set up a framework of policies to govern at-home work and ensure fairness. For example, there could be a standard for how much time each person should spend in the office. The Massachusetts Institute of Technology created a remote pilot project in its Executive Education Program. 30 Employees were encouraged to work remotely two or three days each week and to be present in the office each Wednesday. After six months of the pilot program, 100 percent of the employees recommended its continuation. Link to Learning Watch this video tracing some of the history of workplaces and speculating about innovations in the future, many of which relate to telecommuting to lean more. Keep a list of the telecommuting-specific innovations and identify any ethical concerns related to them. Managers should set clear expectations for remote workers, such as maintaining professionalism while working and accomplishing a certain volume of work or number of tasks by a certain time. Those who meet these goals should be rewarded. In the interests of fairness and equity, neither expectations nor rewards should differ from those established for in-house workers. The ethical employer communicates trust in his or her employees when implementing telecommuting. That trust is based on respect for the employee’s motivation and the recognition that the employee has needs that are important in establishing work-life balance. 31 Perhaps the employer’s vote of confidence in the employee’s ability to work well remotely is the reason that productivity tends to increase in successful telecommuting programs. 32 The Figure 10.4 caption lists some of the best practices of successful telecommuting programs. It would be unethical to place workers without assistance in a new situation in which they can easily fail. Telecommuting workers must be trained in time-management skills so they can maintain their productivity in an environment that may have more or different distractions than a traditional workplace and may make different demands on their time. Training should also strengthen communication skills, such as responding to messages promptly, that help ensure success in a remote setting. To help guard against the risk that telecommuting employees will be unfairly considered “out of sight, out of mind,” the ethical company will adopt written expectations about timely communication in both directions. For instance, it should ensure that managers’ lines of communication are as open to their remote employees as they are to those who can drop by their desk or office to chat. Finally, many firms with successful telecommuting programs create a social network among employees. They sponsor online social occasions to help employees bond even though they are not in the same place. Workers can then find a way to have some virtual fun, despite the distance that might separate them. 33 10.2 Workplace Campuses Learning Objectives By the end of this section, you will be able to: Compare the workplaces of yesterday, today, and the future Describe the benefits and potential drawbacks of workplace campus es Identify ethical challenges in the development of workplace campuses The physical workplace is changing. Most companies still inhabit traditional office spaces in which managers and employees each have an allotted space, whether an office, a cubicle, or just a desk. However, a growing number are redesigning their spaces with fewer separate offices, substituting flexible or shareable work stations built around communal space. 34 The idea is that such “open plan” environments allow for more collaboration and brainstorming because employees are no longer walled off from one another. Shared, multipurpose spaces open to all allow people to gather informally throughout the day. In effect, then, these changes are aimed to augment productivity. In another trend, companies like Apple, Microsoft, Facebook, Amazon, and Alphabet (which owns Google) are developing expansive campus-like facilities that offer generous on-site amenities like recreation centers, fine dining, parks, walking and biking paths, climbing walls, free snacks, child-care facilities, basketball courts, haircuts and massages, and laundry, dry-cleaning, and car wash operations, in airy spaces often powered by renewable energy sources ( Figure 10.5 ). 35 Facebook and Alphabet/Google have plans for building mega-corporate campuses that also include housing. Facebook plans to reserve 15 percent of its housing units for low-income neighbors, but, in both cases, it is anticipated that most residents of these campuses will be employees. 36 Presumably, workers who do not have to commute to and from work every day will be happier and more productive. New workplace arrangements like these effectively serve as fringe benefits for employees that presumably offer the flexibility and work-life balance promised by corporate recruiters. Yet, looking from a different angle, we might consider the motivations behind these complexes to be less than altruistic, because such campuses encourage workers to stay in the office far longer than they might otherwise. Is this the case? Furthermore, if so, do they result in the same or higher levels of productivity? What ethical challenges do they present for the employer and the employee? Workplace Campuses and Historical Precedents Traditional workspaces are designed to allow each person to get the maximum amount of work completed each day, spending most of the time alone in a fairly utilitarian environment with minimal distractions. The size and location of the offices indicate status (corner offices are prized), and lunchrooms or cafeterias and water coolers provide the only place for brief social encounters. State-of-the-art workplaces today, however, incorporate technology and encourage collaboration. Ergonomic furniture is available for comfort, and laptops and tablets allow workers to move around the facility as desktop computers could not. In fact, workers in the new flexible workplace spend less than 50 percent of their time at a desk. 37 Moreover, as we discussed in the previous section, many enjoy the flexibility of telecommuting as needed. Furthermore, in open-plan spaces, all work positions locations are alike; status is not signaled by location or size. Link to Learning Watch this promotional video for one technology company whose employees work in a campus-like setting to learn about some of the benefits. As early as the 1960s, large companies like Bell Labs built suburban compounds for their corporate headquarters, but they were a far cry from the campus settings of Apple and Google today. Bell Labs’ design, for example, was a series of laboratories and office buildings grouped together, with a functional cafeteria. Workplace campuses are also modeled on university campuses that provide a relatively complete work and living environment for students. As noted, Facebook and Google are building apartments near their corporate campuses. Facebook’s new project, named Willow Village, is near Menlo Park, California, and will include some fifteen hundred units. Employees who lease an apartment there will be eligible for a company bonus. 38 The future workplace campuses and mega-corporate campuses with housing bear a superficial resemblance to nineteenth- and early twentieth-century “company towns,” which existed around the world. In a company town, the stores, entertainment venues, and housing were all owned by the same company, which also employed everyone in a local factory or mine. 39 The remote locations of factories sometimes made it necessary for such employers to provide workers with housing and a means to acquire the necessities of life, but those who lived and worked in the company town paid for all purchases from their wages, which, of course, went straight back to the employer. The owners and builders of company towns, like George Pullman or Henry Ford, were often idealists who envisioned creating a social utopia. 40 But the towns and their owners could also be paternalistic and self-serving. Indeed, company towns created what is called a monopsony in the labor market, where there is only a single buyer, and the economic analysis of monopsony shows that with the lack of competition for labor, wages of workers are suppressed. That is, “a monopsonist in the labor market can leverage its market power. Because it is the only firm hiring, it can pay its workers less.” 41 Company towns began to disappear when cars became affordable and employees could drive to work. However, all that driving lengthened some workdays and disrupted the balance people enjoyed between working hours and personal time. Like telecommuting, corporate villages are one approach to cut down drive time. However, critics of Facebook’s Willow Village are calling the property “Zucktown” and wondering whether the development will further blur the work-life balance for employees of Mark Zuckerberg’s social media company. Cases from the Real World Acuity’s Workplace Campus Employees at Acuity, an insurance provider in Sheboygan, Wisconsin, enjoy amenities beyond the imagining of the average U.S. worker. The company offers flexible workdays, on-site leadership training, tuition reimbursement for continuing education, and company scholarships. Its $130 million campus also provides an on-site fitness center complete with a climbing wall, a garden, and a cafeteria serving nutritious meals. Employees are offered the services of an on-site massage therapist, and there are on-site banking and dry-cleaning services. The campus was designed to be a showpiece at the entrance to the town of Sheboygan. In fact, it features a working Ferris wheel and a theater-in-the-round that seats two thousand, which the company makes available for community events and town hall meetings. Critical Thinking What do you think about a company that would build a multimillion-dollar workplace campus that also serves as a center for community events? What does the investment communicate about the company’s core values and stakeholder focus? Should company facilities be only for employees? The Pursuit of Work-Life Balance Twenty-five percent of U.S. employees in multiple industries were recently surveyed and reported feeling “super stressed” as they juggled work and home responsibilities. 42 Daily stress from trying to maintain work-life balance can produce health effects like reduced immunity and inadequate sleep. Stressed workers are also less productive in the workplace. Efforts to offer employees an ever-widening array of amenities appear to be an effort by employers to create work-life balance and make their companies more desirable as places of employment. The idea is that life is simpler if food is readily available and free at work, if a doctor’s office or hair salon is just down the hall, and if home is right on campus. Some research shows that millennials believe integrating work and leisure in some combination fosters work-life balance. 43 They may see less need to have clear boundaries between their work world and their home life as technology pushes them to be connected in so many ways that once did not exist but now seem inescapable (e.g., an employee of a global firm that conducts business around the clock may never be truly separated from the office due to connectivity provided by mobile devices). Have employers then crossed a line with these perks? Have they created an expectation that the employee who works on a corporate campus where all needed services are provided will, in turn, be accessible for long hours of work on a regular basis? Are the amenities really velvet handcuffs that tie employees to work? Living right next to work clearly will reduce commuting time, and via this path, it may promote work-life balance. But the expectation that long hours should be routine just because they are possible will hamper, rather than facilitate, the quest for work-life balance. Furthermore, to the extent that mega-corporate campuses do tie workers to their jobs, reduced worker mobility means that labor markets will be less able to adjust to changing conditions. The Ethical Challenges of Workplace Campuses It is hard to imagine that anyone could find fault with a job that came with all the amenities of a campus-like environment. However, the all-encompassing aspect of these workplaces means a manager’s job description greatly expands to include small-city management functions. As the April 2018 shooting of employees at YouTube’s headquarters suggests, corporate campuses may have a greater need for security, with duties that dovetail those of the city police. Growth of the compound will challenge managers to comply with city planning and zoning regulations. How should these villages within a city contribute to the municipal services they need for the population they draw? Should the city be able to require a greater tax contribution from mega-corporate campus developers that equals the load they add to the city’s fiscal responsibilities? Cases from the Real World A New Slice of the Apple? In 2011, Steve Jobs, founder of Apple, appeared before the Cupertino City Council to present his proposal for a new Apple headquarters on the outskirts of the city. The project, which was approved, is known as the “Ring.” It encompasses 2.8 million square feet and cost some $5 billion to construct. Jobs planned the innovative facility to inspire engineers and programmers charged with creating new Apple devices and tools ( Figure 10.6 ). Its shape is meant to allow them to collaborate while maintaining a connection to nature. Jobs (who died in 2011) also hoped the building would enable Apple to better safeguard its secrets, because it is large enough to house so many employees and data systems in one secure location. The building is sustainable due to solar panels that provide all its energy needs, and the campus includes nine thousand drought-resistant trees planted to withstand a changing climate. Parking is limited by design to encourage employees to use public transportation and share rides. 44 Critics, however, say the Ring’s outer-city location and inward-looking shape, giving many in it a view of only the other side of the building, discourage employees from being a part of Cupertino’s life. 45 Others argue that remodeling an existing building in the heart of the city would have done more for Cupertino’s local economy. Ninety percent of Ring workers are not local; they commute to their jobs, and so they might not have made an impact on the city even if Apple had made a different decision. Shareholders also objected to the facility because of its cost, which may have reduced Apple’s ability to issue more corporate dividends. 46 However, Jobs’ approach to the Apple campus is unquestionably part of a growing trend to create company compounds. Critical Thinking Should a company build in the inner city to integrate its workforce with the community and reduce the traffic consequences of adding its workforce to the local population? Is it better for a company to support local restaurants or build its own restaurant facilities? Is it ethical for a company to spend so much on building a corporate facility instead of increasing shareholder dividends? Should there be zoning laws regarding corporate campuses? 10.3 Alternatives to Traditional Patterns of Work Learning Objectives By the end of this section, you will be able to: Explain the benefits, drawbacks, and ethical issues of job sharing and flextime Describe the business models that have emerged in the new millennium Discuss the ethical challenges businesses face in the gig economy New ideas about the way we work and for how long, as well as the business models we use, are challenging many traditional business strategies. Job sharing and flexible hours (or flextime), the access or sharing economy, and the rise of gig workers all force us to evaluate how they affect management, employees, and customers alike. Although new business models provide increased autonomy and flexibility, they have also led to the rise of what some call the new precariat . 47 The precariat, for “precarious proletariat,” is a new social class of people whose work offers little predictability or security. The existence of such a class raises ethical dilemmas for business managers, who may be tempted to substitute gig workers, to whom benefits like health insurance are ordinarily not provided, for regular employees entitled to costly benefits. 48 Job Sharing and Flextime In job sharing , two or more employees perform the work of a full-time position, each taking part of the total workload for the job. For example, one job-sharing employee might work three eight-hour shifts a week and the other would take two such shifts at the same job. In some ways, job sharing is simply another name for part-time work. The two people need not work equal numbers of hours, but they perform a single job, doing the same tasks and shouldering the same responsibilities. Unlike nurses, who work shifts but each has their own job, job sharers work one job between them. Most people in the United States seek a full-time job of thirty-five hours a week or more, usually because they want the income and benefits (such as health insurance) that often come with such a job. But some are willing to forego full-time work because they need or want to care for children or an elderly or ailing family member, pursue their education, run a business on the side, or volunteer. Allowing two people to share a job is an option that can lead to enhanced work-life balance for both individuals. A job-sharing parent can work weekends only, for example, saving on daycare costs during the week. Many job sharers report less stress and an increased ability to produce high-quality work. Studies have shown that many accomplish more in a shorter workweek due to higher morale. 49 Typically there is less absenteeism when the team can plan around the appointments and vacations of each individual. 50 Job sharing may also reduce the absenteeism of employees with children by providing increased flexibility to cover family emergencies or obligations. There is even a synergistic effect when two people bring their insights to problems that one person would usually face alone. 51 Employers find that hiring two individuals to fill one job also opens the door to recruiting new talent. Job sharing might allow an employer to retain a knowledgeable associate who is ready to cut back work hours. Furthermore, an employee who is leaving or retiring can share the job for a time to train a replacement. Many job sharers apply for jobs as a team. Those who have successfully shared a job advocate for setting clear performance expectations and progress checkpoints. Two employees might share an e-mail account and brief each other daily on their work. 52 Specific examples include translators of legal documents at an international law firm—one translator takes the morning shift; the other, the afternoon. Or technical writers at an engineering firm—one might work Monday through Wednesday noon; the other, Wednesday afternoon through Friday. This scenario works when common documents are being written or translated. If the job sharers are equally competent, work can be passed off to one another at specific intervals. Other aspects of job sharing actually benefit employers, but not necessarily employees. Replacing a full-time position with two or more part-time employees may allow an employer to avoid paying for the benefits to which a full-time employee would be entitled, such as health insurance mandated by the Affordable Care Act, and sometimes optional benefits as well. The number of involuntary part-time workers varies over the course of the business cycle: In 2009, as a consequence of the Great Recession, U.S. Department of Labor statistics put the number of involuntary part-time workers at more than nine million; in mid-2018, that number was just below five million. 53 There are some purely business drawbacks to job sharing. First, the practice does not work in all fields. Second, some work can suffer because of the extra time, and sometimes expense, necessary for coordination between job-sharing partners, especially if neither is formally in charge. 54 Job-sharing arrangements also presuppose that the two people are going to work together collaboratively, but competitive instincts could lead one partner to withhold information or even sabotage the project. Another drawback is the “two Mondays effect”—the potential productivity loss due to the time it takes each partner to get up to speed on the first day back. 55 Finally, some managers do not want the added responsibility of managing two people instead of one. Link to Learning Job sharing has many advantages for employees and employers alike. Watch this video about some of the benefits of job sharing to learn more. The ethical question raised by job sharing boils down to whether the employer is hiring job sharers to improve productivity and meet employee preferences, or hiring part-time workers to improve profitability at the employees’ expense. The ethical employer hires employees to best serve the needs of the customer and the company while respecting the needs of each employee. The first step in ethically managing a job-sharing partnership is to pick the right job to share. Data-entry jobs and those that require less supervision and coordination between partners are more easily managed. Then, with both employees present, the manager should spend some time creating a shared written agreement about procedures to follow and responsibilities to accept. 56 Follow-up is important to be sure job sharers are working cooperatively and meeting their goals. What Would You Do? Staffing Trade-offs You are a department head in a mid-sized clothing manufacturing firm in a time of high unemployment. Your manager is always worrying about the bottom line and cash flow. She has asked you, as marketing employees retire or leave, to split a number of their positions into part-time jobs that do not require the company to offer benefits like health insurance. Your boss says many job applicants want this kind of employment. You are not so sure. You are reluctant to replace jobs offering good benefits with jobs that offer none, and you are seeking powerful arguments with which to persuade your boss to abandon the plan. Critical Thinking What points support the job-sharing plan? How would it benefit the company? The employees? What negative effects might it have on the company and the employees? Is job sharing better for some positions in a department than for others? Do you have any concerns about potential employment discrimination if this plan is implemented? If so, what would they be? Is creating job-sharing positions the right thing for the company/customers/employees to do in this situation? The practice of offering flexible hours, or flextime , lets employees choose their own start and finish time each day, arriving and leaving earlier or later than the normal 9-to-5 workday. Parents benefit particularly because they are better able to schedule their work around their children’s lives. Women are the predominant users of this family-friendly work policy. 57 Flextime was a starting place for creative new approaches to work. Teams now trade shifts to accommodate members’ needs for time off. Some companies allow a compressed work week that caters to the efficient employee who can get a week’s work done in less than forty hours. In some professions, such as accounting, employees might be allowed a reduced schedule during the off season. 58 All these variations allow employers to recruit a more diverse workforce. No longer is it necessary that someone be free of weekday responsibilities to have full-time work and gainful employment. Flextime also benefits clients and customers because companies can extend their hours of operation when workers are willing to cover flexible shifts. 59 Ethical employers base the decision to allow flextime on a clear and well-written policy that relies on objective job-related criteria. Without an objective policy, employees could claim discrimination if all were not eligible. 60 Employers should also be aware of the law; in some states, daily work hours are set by law, and allowing some employees to work more than eight hours a day might require payment of overtime. Some studies have found a troubling bias against employees who request a later start to the workday. 61 Managers may incorrectly regard people who prioritize an early start as more desirable employees and attribute a request for a late start to lack of motivation. Managers need greater supervisory skills to ensure flextime workers are using their time productively and to effectively manage teams in which some are working flexible hours and others are not. The Access Economy and Online Platforms The access economy is essentially a resource circulation system in which consumers participate on both sides of a transaction, as both providers and obtainers of resources (the transaction is usually facilitated by a third party acting as a go-between). The model, sometimes called peer-to-peer (or P2P), is particularly popular when the asset is expensive to obtain and is not fully consumed by the user (such as a house or condo). In the traditional capitalist economic model, goods are bought and sold by businesses and individuals, but in the access or sharing economy, goods and services are traded on the basis of access rather than ownership. In this business model, owners make money from underused assets. The global online hospitality marketplace is an example. Airbnb says consumer-hosts in San Francisco who rent out their homes do so for an average of about sixty nights a year, making almost $10,000 from such rentals. Car owners using the service RelayRides make an average of $250 a month from allowing others to use their cars. This helps consumers supplement their incomes or even finance the purchase of the assets they share. Many of the original sharing-economy businesses are now household names, including Airbnb, Uber, and Lyft; thousands more are part of the P2P decentralized markets. Most sharing or collaborative economy business models use the Internet to facilitate transactions, so it might be more accurate to refer to them as part of the online platform economy . However, whereas some facilitate the renting of assets, such as real estate (think Airbnb), others are essentially selling labor (think Task Rabbit), and some bridge the two categories by offering a combination (think Lyft) (see Figure 10.7 ). The new business models all have something in common, however: a decentralized and democratized marketplace featuring broad-scale participation, with consumers serving multiple roles. Online and digital business models allow almost anyone to start a business from scratch in what some call the democratization of free enterprise. An economy so open to new players is a significant step toward increased buyer access to goods and services at all levels, even as it raises legitimate questions about how to ensure trust between the transacting parties. One issue facing the access economy is regulation. For example, should private individuals who rent out rooms be regulated like a Marriott hotel or perhaps a bed-and-breakfast operator, or simply be considered consumers allowing a guest to stay in their house? They are not only subject to income taxes on the money they earn but they are increasingly likely to be charged hotel or occupancy taxes. Some cities have passed ordinances to limit real estate rentals to minimum stays of a week or a month; shorter stays will be considered hotel rentals subject to regulations such as health and safety code rules. In the ride-sharing segment, some cities have said drivers must undergo the same scrutiny as taxi or limousine drivers, such as fingerprinting, commercial licensing, training, and background checks. The access economy presents an ethical and regulatory challenge for all levels of government—balancing the need to have at least some rules to protect consumers with the desire to allow competition from new business models. Big businesses are lobbying legislative bodies to apply the same regulation to the access economy as to the traditional economy in an effort to reduce or eliminate the threat of competition. This, in turn, raises an ethical question for society as a whole. Traditional means of raising capital, whether through initial public offerings (IPOs) or venture capital, are often dominated by big players. Should access to capital remain limited to those who have influence, or should the government pursue policies aimed at facilitating access to capital by small businesses? In one sign of increasing acceptance of the access economy, traditional businesses are starting to invest in smaller, more nimble, platforms, as the following feature on Oasis Collections demonstrates. Cases from the Real World Oasis Collections Oasis Collections is a real estate rental marketplace or platform similar to Airbnb, with a few key differences. Founded in 2009, the company fills a market niche by matching house and condo owners with travelers who want something more personal than a hotel but more upscale than a room in someone’s house. Oasis sought venture capital funding but was turned down multiple times. An IPO was not feasible because the company was too small. This financing quandary demonstrates the limited access to capital that often forms a barrier for entrepreneurial startups to overcome. Oasis’ founders turned to sources often used by entrepreneurs, including a mix of seed funding from founders, friends, and family, and angel funding from a private investor. The company operated on a relatively tight budget for several years. In 2017, Hyatt Hotels decided to invest $20 million in Oasis, after it had proven it had a niche in the access economy. Steve Haggerty, Hyatt’s global head of capital strategy, said the investment “reflects Hyatt’s established strategy to super serve the high-end traveler by offering new experiences beyond traditional hotel stays. Travelers who book Oasis Collections homes are . . . leisure and often business travelers who seek more space for a longer time, but also want the peace of mind, personalized service and amenities they expect when staying with Hyatt.” 62 Hyatt apparently now sees the access economic model as a force it cannot afford to ignore and has chosen to embrace and fund it. Oasis has the capital to expand its footprint, so CEO Parker Stanberry spends most of his time traveling to sign up new properties and new customers. “We definitely have our work cut out for us,” he says. “We’ve got to hustle hard every day.” 63 Critical Thinking Can a sixty-year-old traditional hospitality corporation and a new access-economy startup thrive side by side? Or will the experiment crash and burn? How likely is it that a big business in a similar type of industry would buy up the related access-economy business or use their market power to crush them instead of integrating the new model as Hyatt did? Defend your answer. As the Oasis case shows, getting access to funding is often a challenge for entrepreneurs. An IPO is essentially a method of funding a startup by selling its stock to the public at large, a process heavily regulated by the government. The Securities and Exchange Commission (SEC) oversees the applicable federal laws, which require the filing of a registration statement and a full disclosure of financial information, along with months of effort by accountants, attorneys, underwriters, and company executives. The cost and complexity of this process usually outweighs the benefit for entrepreneurs who want to raise a modest amount of capital ($10 million or less). However, as a matter of business ethics, businesses of all sizes should be able to participate fully in the U.S. economy and not be shut out by the “gatekeepers of capital”—the investment banking community. Thus, in 2012, Congress enacted new legislation called the JOBS (Jumpstart Our Business Startups) Act, which amended U.S. securities laws to enable small businesses to use a variation on a technique known as crowdfunding. Crowdfunding is already in use as a way to give or lend money to consumers and businesses through web portals such as GoFundMe. But those sites do not offer SEC-compliant sales of securities in a business, as the JOBS Act now permits emerging growth companies (EGCs) seeking capital to do. This new type of funding should help level the playing field for EGCs; many view it as a way of democratizing access to capital. 64 One entrepreneurial startup that used this new method successfully is Betabrand, a San Francisco–based retail clothing company that doubles as a crowdfunding platform. The company lets users of its platform crowdsource clothing concepts and develop prototypes into actual products. Link to Learning This website connects to one of several active business-oriented crowdfunding websites to offer emerging growth companies or small business several avenues of funding, including equity, convertible notes, and debt. The primary advantage is the opportunity to raise equity capital without big fees and red tape. The Gig Economy Opportunities for limited-term employment, sometimes referred to as “gigs,” have existed for decades in the music and entertainment industry; they have even been likened to the widespread small-scale self-employment typical of the pre-union and pre-Industrial eras. 65 What is new about gig work today is that it is often made possible by technology, which frees workers from the need to travel to the employer’s workplace and allows them to work multiple jobs at once. This offers workers, and perhaps even managers, a new set of advantages and disadvantages in the employment equation. The gig economy is an environment in which individuals and businesses contract with independent workers for short-term assignments, engagements, or projects, offering few or no benefits beyond compensation. A freelancer or contractor is a self-employed worker who may work with more than one client but who usually has a contract that covers the details of the job, including compensation. The terms freelancer and contractor are generally used interchangeably. However, if there is a distinction, it is that a freelancer is almost always self-employed and works for multiple companies, whereas a contractor may or may not be self-employed and may work for only one company at a time ( Figure 10.8 ). Some may be happily committed to their independent status; others are involuntarily self-employed while they search for more permanent or full-time positions. Gigs might be full- or part-time; they might be limited to a specific task or a specific time; and they may serve as the worker’s sole employment or as a “moonlighting” job. Regardless of the terminology, the trend toward a gig economy has begun. A recent study by Intuit predicted that by 2020, a surprisingly large 40 percent of U.S. workers would be independent contractors, and according to the Freelancers Union, more than 55 million adults in the United States (that is, 35 percent of the U.S. workforce) already work as independent contractors and/or moonlighters. 66 The nature of freelance work leaves some workers searching for the qualities of traditional full-time work, and the Freelancers Union has attempted to provide them by giving its more than 375,000 members a voice through policy advocacy and access to some group benefits. 67 Many people value the flexibility of freelance work hours. They work off premises (frequently at home), make their own schedules, and juggle assignments as needed. However, benefits such as health care and retirement plans are usually unavailable (unless an employment agency sponsors them for those it places in temporary work). Freelancers most often must establish their own retirement accounts and obtain their own health insurance through an employed spouse or partner or in a health care insurance exchange. Robert B. Reich, the former Secretary of Labor and professor at the University of California, Berkeley, says, “This on-demand economy means a work life that is unpredictable, doesn’t pay very well, and is terribly insecure.” 68 Unlike employees on the payroll, gig workers must also pay both the employee’s and the employer’s halves of the federal payroll tax (referred to as FICA [Federal Contributions Insurance Act], which funds Social Security and Medicare). This combined tax currently totals 15.3 percent of a freelancer’s earnings. Payroll taxes overall bring in about 24 percent of combined federal, state, and local government revenue, 69 making them the second-largest source of government revenue in the United States after individual federal income taxes. Here is one of the ethical issues employers face: Are they dodging their fair share of taxes and failing to offer benefits by forcing people who could be their employees into contract work instead? Cases from the Real World Gig Work Have you ever been a gig worker? A recent study found that 37 percent of U.S. workers participate in the gig economy, and government and other estimates say 40 percent will be working outside traditional full-time jobs by 2020. Clearly the gig economy is not a fad. The issue is often whether it benefits only the company or also the worker. Do people actually like being gig workers, or has the economy forced them into it, sometimes by taking second and third jobs? A national survey by the Freelancers Union found that two in three of the 55 million U.S. workers who freelanced in 2016 did so because they wanted to, not because they were forced to; the other one-third did it out of necessity. 70 Although motivations for gig work may vary, it is clear that employers are benefitting. Of course, part-time contract workers are not new. What is new is the way gig work has spread to many white-collar professions. Here are two examples. Joseph creates websites for a marketing company and a digital content studio. He also creates and edits motion graphics. “It’s been a fun ride, tiring but fun,” he says. “Finding time is always the struggle. I’m working on a freelance project every weekend.” Joseph thinks gig work has helped him improve his graphic skills faster than he might have done in a traditional job. “I get to move around to different companies, and if one thing falls out, I still have other things I can fall back on—and it keeps me sharp.” Nicole, a mother of three, is a full-time clerk at a law firm, but she decided she needed extra money and signed up with a work-at-home call center. Her husband has joined too. Nicole says her gig job is one she could continue when she retires, and she likes that possibility. 71 “This is the future of work,” says Diane Mulcahy, a private equities investor whose clients often benefit financially from the use of gig workers. “The full-time employee is getting to be the worker of last resort.” 72 Critical Thinking Aside from the lack of benefits, what are the potentially negative effects for society of the gig economy? What happens to the concept of loyalty between worker and employer if we move to a mostly gig economy? Will that result be negative or positive? For whom, and why? Microsoft was one of the first companies to save huge amounts of money by hiring contract workers, avoiding paying benefits and payroll taxes and escaping a wide variety of employment and labor laws. However, the company found itself the object of legal action by both the Internal Revenue Service (IRS) and its contract workers on the grounds that a large portion of its contract workforce should have been classified as employees instead. Microsoft ended up conceding the IRS position that the workers were de facto employees. It issued W-2s (earnings statements) for the workers’ past two years and paid its share of payroll taxes. It hired some of the workers as well, but others sued for fringe benefits they had been denied as freelancers. After lengthy litigation and appeals, in 2000, Microsoft agreed to pay thousands of plaintiffs a total of $97 million, the value of stock options they would have received if it had employed them. It was the largest settlement ever received by a group of temporary employees. Today, Microsoft has more 110,000 employees, and about 75 percent are temporary or contract workers. However, Microsoft says it now requires staffing companies to give temporary and gig workers it hires fringe benefits. 73 A particularly hazy work relationship exists between employers and interns. Many business or other professional-track students seek—indeed, are encouraged to find— internships while still in school. Sometimes these positions are paid, sometimes not; some carry academic credit and some do not. The tasks interns perform, and therefore the quality of the professional experiences they gain, can vary widely. However, many interns clearly function as a source of unpaid labor. Ethical boundaries are often crossed, even if students are willing to undertake these positions. Although state labor laws governing internships vary, responsible companies will insist that their interns are paid for their services or receive academic credit, or both. 10.4 Robotics, Artificial Intelligence, and the Workplace of the Future Learning Objectives By the end of this section, you will be able to: Discuss the application of robotics and the workplace changes it will bring Identify artificial intelligence applications in the workplace Explain the ethical challenges presented by the use of artificial intelligence As we have seen earlier in this chapter, general advances in computer technology have already enabled significant changes in the workplace. In this module, we will look at how future workforce demographics may be affected by existing and emerging technologies. The combination of automation and robotics has already changed not only the workplace but everyday life as well. It also comes with a host of ethical and legal issues, not least being where humans will fit in the workplace of tomorrow. Managers of the future may ask, “Does my company or society benefit from having a human do a job rather than a robot, or is it all about efficiency and cost?” Robotics and Automation in the Workplace Advances in the field of robotics —a combination of computer science, mechanical and electronics engineering, and science—have meant that machines or related forms of automation now do the work of humans in a wide variety of settings, such as medicine, where robots perform surgeries previously done by the surgeon’s hand. Robots have made it easier and cheaper for employers to get work done. The downside, however, is that some reasonably well-paying jobs that provided middle-class employment for humans have become the province of machines. A McKinsey Global Institute study of eight hundred occupations in nearly fifty countries showed that more than 800 million jobs, or 20 percent of the global workforce, could be lost to robotics by the year 2030. 74 The effects could be even more pronounced in wealthy industrialized nations, such as the United States and Germany, where researchers expect that up to one-third of the workforce will be affected. By 2030, the report estimates that 39 million to 73 million jobs may be eliminated in the United States. Given that the level of employment in the United States in mid-2018 is approaching 150 million workers, this potential loss of jobs represents roughly one-quarter to one-half of total current employment (but a smaller share of employment in 2030 because of future population and employment growth). The big question, then, is what will happen to all these displaced workers. The McKinsey report estimates that about twenty million of them will be able to transfer easily to other industries for employment. But this still leaves between twenty million and more than fifty million displaced workers who will need new employment. Occupational retraining is likely to be a path taken by some, but older workers, as well as geographically immobile workers, are unlikely to opt for such training and may endure job loss for protracted periods. In developing countries, the report predicts that the number of jobs requiring less education will shrink. Furthermore, robotics will have less impact in poorer countries because these nations’ workers are already paid so little that employers will save less on labor costs by automating. According to the report, for example, by the same date of 2030, India is expected to lose only about 9 percent of its jobs to emerging technology. Which occupations will be most heavily affected? Not surprisingly, the McKinsey report concludes that machine operators, factory workers, and food workers will be hit hardest, because robots can do their jobs more precisely and efficiently. “It’s cheaper to buy a $35,000 robotic arm than it is to hire an employee who’s inefficiently making $15 an hour bagging French fries,” said a former McDonald’s CEO in another article about the consequences of robots in the labor market. 75 He estimated that automation has already cut the number of people working in a McDonald’s by half since the 1960s and that this trend will continue. Other hard-hit jobs will include mortgage brokers, paralegals, accountants, some office staff, cashiers, toll booth operators, and car and truck drivers. The Bureau of Labor Statistics (BLS) estimates that eighty thousand fast-food jobs will disappear by 2024. As growing numbers of retail stores like Walmart, CVS, and McDonald’s provide automated self-checkout options, it has been estimated that 7.5 million retail jobs are at risk over the course of the next decade. Furthermore, it has been estimated that as self-driving cars and trucks replace automobile and truck drivers, five million jobs will be lost in the early 2020s. Jobs requiring human interaction are typically at low risk for being replaced by automation. These include nurses and most physicians, lawyers, teachers, and bartenders, as well as social workers (estimated by the BLS to grow by 19 percent by 2024), hairstylists and cosmetologists, youth sports coaches, and songwriters. McKinsey also anticipates that specialized lower-wage jobs like gardening, plumbing, and care work will be less affected by automation. The challenge to the economy, then, will be how to address the prospect of substantial job loss; about twenty million to fifty million people will not be able to easily find new jobs. The McKinsey report notes that new technology, as in the past, will generate new types of jobs. But this is unlikely to help more than a small fraction of those confronting unemployment. So the United States will likely face some combination of rapidly rising unemployment, an urgent need to retrain twenty million or more workers, and recourse to policies whereby the government serves as an employer of last resort. Ethics Across Time and Cultures Advances in Robotics in Japan Japan has long maintained its position as the world’s top exporter of robots, selling nearly 50 percent of the global market share in terms of both units and dollar value. At first, Japan’s robots were found mainly in factories making automobiles and electronic equipment, performing simple jobs such as assembling parts. Now Japan is poised to take the lead by putting robots in diverse areas including aeronautics, medicine, disaster mitigation, and search and rescue, performing jobs that human either cannot or, for safety reasons (such as defusing a bomb), should not do. Leading universities such as the University of Tokyo offer advanced programs to teach students not only how to create robots but also how to understand the way robot technology is transforming Japanese society. Universities, research institutions, corporations, and government entities are collaborating to implement the country’s next generation of advanced artificial intelligence robot technology, because Japan truly sees the rise of robotics as the “Fourth Industrial Revolution.” New uses of robots include hazardous cleanup in the wake of the 2011 earthquake and tsunami disaster that destroyed the Fukushima Daiichi nuclear power plant. After those events, Japan accelerated its development and application of disaster-response robots to go into radioactive areas and handle remediation. In the laboratory at the University of Tokyo School of Engineering, advances are also being made in technology that mimics the capabilities of the human eye. One application allows scientists a clear field of vision in extreme weather conditions that are otherwise difficult or impossible for humans to study. Japanese researchers are also developing a surgical robotic system with a three-dimensional endoscope to conduct high-risk surgery in remote mountainous regions with no specialized doctors. This system is in use in operating rooms in the United States as well, but Japan is taking it a step further by using it in teletherapy, where the patient is hundreds of miles away from the doctor actually performing the surgery. In Japan’s manufacturing culture, robots are viewed not as threats but as solutions to many of the nation’s most critical problems. Indeed, with Japan’s below-replacement fertility since the mid-1970s, Japan’s work force has been aging quite rapidly; in fact, beginning in the period from 2010 to 2015, the Japanese population started shrinking. Clearly, robots are potentially quite important as a means to offset prospective adverse consequences of a diminishing labor force. Critical Thinking Does using robots cause a loss of jobs, a shifting of jobs, or both? How should society respond? How might the use of robots add to the increasing inequality in the U.S. economy? Do companies have an ethical responsibility to their workers to training or other support to workers displaced by automation? Artificial Intelligence Although some robots are remotely controlled by a human operator or a computer program written by a human, robots can also learn to work without human intervention, and often faster, more efficiently, and more cheaply than humans can. The branch of science that uses computer algorithms to replicate human intelligent behavior by machines with minimal human intervention is called artificial intelligence (AI) . Related professions in which the implementation of AI might have particular impact are banking, financial advising, and the sales of securities and managing of stock portfolios. According to global consulting giant Accenture, AI is “a collection of advanced technologies that allows machines to sense, comprehend, act and learn.” Accenture contends that AI will be the next great advance in the workplace: “It is set to transform business in ways we have not seen since the Industrial Revolution; fundamentally reinventing how businesses run, compete and thrive. When implemented holistically, these technologies help improve productivity and lower costs, unlocking more creative jobs and creating new growth opportunities.” 76 Accenture looked at twelve of the world’s most developed countries, which account for more than half of world economic output, to assess the impact of AI in sixteen specific industries. According to its report, AI has the potential to significantly increase corporate profitability, double rates of economic growth by 2035, increase labor productivity by as much as 40 percent, and boost gross value added by $14 trillion by 2035, based on an almost 40 percent increase in rates of return. 77 Even news articles have begun to be written by robots. 78 Link to Learning Read this article about AI and its applications and watch this video about how automation and AI are changing the accounting profession to learn more. Also, read this article about how some startups are creating new AI-related technology and products to automate accounting systems to learn more. A report by KPMG, another global consulting and accounting firm, indicates that almost 50 percent of the activities people perform in the workplace today could be automated, most often by using AI and automation technology that already exist. The ethical question facing the business community, and all of us on a broader level, is about the type of society in which we all want to live and the role automation will play in it. The answer is not simply about efficiency; a company should consider many variables as it moves toward increased automation ( Figure 10.9 ). For example, as AI programs become better able to interact with humans, especially online, should a company be required to inform its customers if and when they are dealing with any form of AI and not a person? If people cannot tell when they are communicating with an AI program and not a human being, has an AI-controlled computer or robot reached a form personhood? Why or why not? Although traditional business ethics can provide us with a starting place to answer such questions, we will also need a philosophical approach, because we also need to decide whether it is necessary to have consciousness to be considered a person. This issue is further muddied when a human employee largely is tapping AI i to serve customers or clients. Should this combination of human and AI assistance be made patently clear? Another issue in AI and all forms of automation is liability. According to Reuters News, “lawmakers in Europe have agreed on the need for [European Union]-wide legislation that would regulate robots and their use, including an ethical framework for their development and deployment, as well as the establishment of liability for the actions of robots, including self-driving cars.” 79 The legal and ethical questions in assigning liability for decisions made by robots and AI are not only fascinating to debate but also an important legal matter society must resolve. The answers will one day directly affect the day-to-day lives of billions of people.
u.s._history
Summary 22.1 Turner, Mahan, and the Roots of Empire In the last decades of the nineteenth century, after the Civil War, the United States pivoted from a profoundly isolationist approach to a distinct zeal for American expansion. The nation’s earlier isolationism originated from the deep scars left by the Civil War and its need to recover both economically and mentally from that event. But as the industrial revolution changed the way the country worked and the American West reached its farthest point, American attitudes toward foreign expansion shifted. Businesses sought new markets to export their factory-built goods, oil, and tobacco products, as well as generous trade agreements to secure access to raw materials. Early social reformers saw opportunities to spread Christian gospel and the benefits of American life to those in less developed nations. With the rhetoric of Fredrick J. Turner and the strategies of Alfred Mahan underpinning the desire for expansion abroad, the country moved quickly to ready itself for the creation of an American empire. 22.2 The Spanish-American War and Overseas Empire In the wake of the Civil War, American economic growth combined with the efforts of Evangelist missionaries to push for greater international influence and overseas presence. By confronting Spain over its imperial rule in Cuba, the United States took control of valuable territories in Central America and the Pacific. For the United States, the first step toward becoming an empire was a decisive military one. By engaging with Spain, the United States was able to gain valuable territories in Latin America and Asia, as well as send a message to other global powers. The untested U.S. Navy proved superior to the Spanish fleet, and the military strategists who planned the war in the broader context of empire caught the Spanish by surprise. The annexation of the former Spanish colonies of Guam, Puerto Rico, and the Philippines, combined with the acquisition of Hawaii, Samoa, and Wake Island, positioned the United States as the predominant world power in the South Pacific and the Caribbean. While some prominent figures in the United States vehemently disagreed with the idea of American empire building, their concerns were overruled by an American public—and a government—that understood American power overseas as a form of prestige, prosperity, and progress. 22.3 Economic Imperialism in East Asia The United States shifted from isolationism to empire building with its involvement—and victory—in the Spanish-American War. But at the same time, the country sought to expand its reach through another powerful tool: its economic clout. The Industrial Revolution gave American businesses an edge in delivering high-quality products at lowered costs, and the pursuit of an “open door” policy with China opened new markets to American goods. This trade agreement allowed the United States to continue to build power through economic advantage. 22.4 Roosevelt’s “Big Stick” Foreign Policy When Roosevelt succeeded McKinley as president, he implemented a key strategy for building an American empire: the threat, rather than the outright use, of military force. McKinley had engaged the U.S. military in several successful skirmishes and then used the country’s superior industrial power to negotiate beneficial foreign trade agreements. Roosevelt, with his “big stick” policy, was able to keep the United States out of military conflicts by employing the legitimate threat of force. Nonetheless, as negotiations with Japan illustrated, the maintenance of an empire was fraught with complexity. Changing alliances, shifting economic needs, and power politics all meant that the United States would need to tread carefully to maintain its status as a world power. 22.5 Taft’s “Dollar Diplomacy” All around the globe, Taft sought to use U.S. economic might as a lever in foreign policy. He relied less on military action, or the threat of such action, than McKinley or Roosevelt before him; however, he both threatened and used military force when economic coercion proved unsuccessful, as it did in his bid to pay off Central America’s debts with U.S. dollars. In Asia, Taft tried to continue to support the balance of power, but his efforts backfired and alienated Japan. Increasing tensions between the United States and Japan would finally explode nearly thirty years later, with the outbreak of World War II.
Chapter Outline 22.1 Turner, Mahan, and the Roots of Empire 22.2 The Spanish-American War and Overseas Empire 22.3 Economic Imperialism in East Asia 22.4 Roosevelt’s “Big Stick” Foreign Policy 22.5 Taft’s “Dollar Diplomacy” Introduction As he approached the rostrum to speak before historians gathered in Chicago in 1893, Frederick Jackson Turner appeared nervous. He was presenting a conclusion that would alarm all who believed that westward expansion had fostered the nation’s principles of democracy. His conclusion: The frontier—the encounter between European traditions and the native wilderness—had played a fundamental role in shaping American character, but the American frontier no longer existed. Turner’s statement raised questions. How would Americans maintain their unique political culture and innovative spirit in the absence of the frontier? How would the nation expand its economy if it could no longer expand its territory? Later historians would see Turner’s Frontier Thesis as deeply flawed, a gross mischaracterization of the West. But the young historian’s work greatly influenced politicians and thinkers of the day. Like a muckraker, Turner exposed the problem; others found a solution by seeking out new frontiers in the creation of an American empire. The above advertisement for a theater reenactment of the Spanish-American War ( Figure 22.1 ) shows the American appetite for expansion. Many Americans felt that it was time for their nation to offer its own brand of international leadership and dominance as an alternative to the land-grabbing empires of Europe.
[ { "answer": { "ans_choice": 1, "ans_text": "B" }, "bloom": null, "hl_context": "On the eve of the Civil War , the country lacked the means to establish a strong position in international diplomacy . <hl> As of 1865 , the U . S . State Department had barely sixty employees and no ambassadors representing American interests abroad . <hl> Instead , only two dozen American foreign ministers were located in key countries , and those often gained their positions not through diplomatic skills or expertise in foreign affairs but through bribes . <hl> Further limiting American potential for foreign impact was the fact that a strong international presence required a strong military — specifically a navy — which the United States , after the Civil War , was in no position to maintain . <hl> Additionally , as late as 1890 , with the U . S . Navy significantly reduced in size , a majority of vessels were classified as “ Old Navy , ” meaning a mixture of iron hulled and wholly wooden ships . While the navy had introduced the first all-steel , triple-hulled steam engine vessels seven years earlier , they had only thirteen of them in operation by 1890 . <hl> During the time of Reconstruction , the U . S . government showed no significant initiative in foreign affairs . <hl> Western expansion and the goal of Manifest Destiny still held the country ’ s attention , and American missionaries proselytized as far abroad as China , India , the Korean Peninsula , and Africa , but reconstruction efforts took up most of the nation ’ s resources . As the century came to a close , however , a variety of factors , from the closing of the American frontier to the country ’ s increased industrial production , led the United States to look beyond its borders . Countries in Europe were building their empires through global power and trade , and the United States did not want to be left behind .", "hl_sentences": "As of 1865 , the U . S . State Department had barely sixty employees and no ambassadors representing American interests abroad . Further limiting American potential for foreign impact was the fact that a strong international presence required a strong military — specifically a navy — which the United States , after the Civil War , was in no position to maintain . During the time of Reconstruction , the U . S . government showed no significant initiative in foreign affairs .", "question": { "cloze_format": "The United States express limited interest in overseas expansion in the 1860s and 1870s because of ___.", "normal_format": "Why did the United States express limited interest in overseas expansion in the 1860s and 1870s?", "question_choices": [ "fear of attacks on their borders", "post-Civil War reconstruction", "the Anti-Imperialist League", "Manifest Destiny" ], "question_id": "fs-idm33938544", "question_text": "Why did the United States express limited interest in overseas expansion in the 1860s and 1870s?" }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 2, "ans_text": "the reopening of the American frontier" }, "bloom": null, "hl_context": "While Turner provided the idea for an empire , Mahan provided the more practical guide . In his 1890 work , The Influence of Seapower upon History , he suggested three strategies that would assist the United States in both constructing and maintaining an empire . <hl> First , noting the sad state of the U . S . Navy , he called for the government to build a stronger , more powerful version . <hl> <hl> Second , he suggested establishing a network of naval bases to fuel this expanding fleet . <hl> Seward ’ s previous acquisition of the Midway Islands served this purpose by providing an essential naval coaling station , which was vital , as the limited reach of steamships and their dependence on coal made naval coaling stations imperative for increasing the navy ’ s geographic reach . Future acquisitions in the Pacific and Caribbean increased this naval supply network ( Figure 22.5 ) . Finally , Mahan urged the future construction of a canal across the isthmus of Central America , which would decrease by two-thirds the time and power required to move the new navy from the Pacific to the Atlantic oceans . Heeding Mahan ’ s advice , the government moved quickly , passing the Naval Act of 1890 , which set production levels for a new , modern fleet . By 1898 , the government had succeeded in increasing the size of the U . S . Navy to an active fleet of 160 vessels , of which 114 were newly built of steel . <hl> In addition , the fleet now included six battleships , compared to zero in the previous decade . <hl> <hl> As a naval power , the country catapulted to the third strongest in world rankings by military experts , trailing only Spain and Great Britain . <hl>", "hl_sentences": "First , noting the sad state of the U . S . Navy , he called for the government to build a stronger , more powerful version . Second , he suggested establishing a network of naval bases to fuel this expanding fleet . In addition , the fleet now included six battleships , compared to zero in the previous decade . As a naval power , the country catapulted to the third strongest in world rankings by military experts , trailing only Spain and Great Britain .", "question": { "cloze_format": "Mahan did not believe ___ was needed to build an American empire.", "normal_format": "Which of the following did Mahan not believe was needed to build an American empire?", "question_choices": [ "a navy", "military bases around the world", "the reopening of the American frontier", "a canal through Central America" ], "question_id": "fs-idm146685456", "question_text": "Which of the following did Mahan not believe was needed to build an American empire?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 1, "ans_text": "fear that the United States would suffer a foreign invasion" }, "bloom": null, "hl_context": "Domestically , the country was neither unified in their support of the treaty nor in the idea of the United States building an empire at all . Many prominent Americans , including Jane Addams , former President Grover Cleveland , Andrew Carnegie , Mark Twain , and Samuel Gompers , felt strongly that the country should not be pursuing an empire , and , in 1898 , they formed the Anti-Imperialist League to oppose this expansionism . <hl> The reasons for their opposition were varied : Some felt that empire building went against the principles of democracy and freedom upon which the country was founded , some worried about competition from foreign workers , and some held the xenophobic viewpoint that the assimilation of other races would hurt the country . <hl> Regardless of their reasons , the group , taken together , presented a formidable challenge . As foreign treaties require a two-thirds majority in the U . S . Senate to pass , the Anti-Imperialist League ’ s pressure led them to a clear split , with the possibility of defeat of the treaty seeming imminent . Less than a week before the scheduled vote , however , news of a Filipino uprising against American forces reached the United States . Undecided senators were convinced of the need to maintain an American presence in the region and preempt the intervention of another European power , and the Senate formally ratified the treaty on February 6 , 1899 .", "hl_sentences": "The reasons for their opposition were varied : Some felt that empire building went against the principles of democracy and freedom upon which the country was founded , some worried about competition from foreign workers , and some held the xenophobic viewpoint that the assimilation of other races would hurt the country .", "question": { "cloze_format": "___ is not one of the reasons the Anti-Imperial League gave for opposing the creation of an American empire.", "normal_format": "Which is not one of the reasons the Anti-Imperial League gave for opposing the creation of an American empire?", "question_choices": [ "fear of competition from foreign workers", "fear that the United States would suffer a foreign invasion", "concerns about the integration of other races", "concerns that empire building ran counter to American democratic principles" ], "question_id": "fs-idp68175888", "question_text": "Which is not one of the reasons the Anti-Imperial League gave for opposing the creation of an American empire?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 0, "ans_text": "A" }, "bloom": null, "hl_context": "<hl> In 1899 , Secretary of State Hay made a bold move to acquire China ’ s vast markets for American access by introducing Open Door notes , a series of circular notes that Hay himself drafted as an expression of U . S . interests in the region and sent to the other competing powers ( Figure 22.12 ) . <hl> These notes , if agreed to by the other five nations maintaining spheres of influences in China , would erase all spheres and essentially open all doors to free trade , with no special tariffs or transportation controls that would give unfair advantages to one country over another . Specifically , the notes required that all countries agree to maintain free access to all treaty ports in China , to pay railroad charges and harbor fees ( with no special access ) , and that only China would be permitted to collect any taxes on trade within its borders . While on paper , the Open Door notes would offer equal access to all , the reality was that it greatly favored the United States . <hl> Free trade in China would give American businesses the ultimate advantage , as American companies were producing higher-quality goods than other countries , and were doing so more efficiently and less expensively . <hl> The “ open doors ” would flood the Chinese market with American goods , virtually squeezing other countries out of the market .", "hl_sentences": "In 1899 , Secretary of State Hay made a bold move to acquire China ’ s vast markets for American access by introducing Open Door notes , a series of circular notes that Hay himself drafted as an expression of U . S . interests in the region and sent to the other competing powers ( Figure 22.12 ) . Free trade in China would give American businesses the ultimate advantage , as American companies were producing higher-quality goods than other countries , and were doing so more efficiently and less expensively .", "question": { "cloze_format": "Hay's suggestion of an open door policy in China benefit the United States over other nations because ___.", "normal_format": "How did Hay’s suggestion of an open door policy in China benefit the United States over other nations?", "question_choices": [ "The United States produced goods of better quality and lower cost than other countries.", "The United States enjoyed a historically stronger relationship with the Chinese government.", "The United States was the only nation granted permission to collect taxes on the goods it traded within China’s borders.", "The United States controlled more foreign ports than other countries." ], "question_id": "fs-idp419846992", "question_text": "How did Hay’s suggestion of an open door policy in China benefit the United States over other nations?" }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 1, "ans_text": "The United States provided troops to fight the rebels." }, "bloom": null, "hl_context": "<hl> The notes were invoked barely a year later , when a group of Chinese insurgents , the Righteous and Harmonious Fists — also known as the Boxer Rebellion ( 1899 ) — fought to expel all western nations and their influences from China ( Figure 22.13 ) . <hl> <hl> The United States , along with Great Britain and Germany , sent over two thousand troops to withstand the rebellion . <hl> <hl> The troops signified American commitment to the territorial integrity of China , albeit one flooded with American products . <hl> Despite subsequent efforts , by Japan in particular , to undermine Chinese authority in 1915 and again during the Manchurian crisis of 1931 , the United States remained resolute in defense of the open door principles through World War II . Only when China turned to communism in 1949 following an intense civil war did the principle become relatively meaningless . <hl> However , for nearly half a century , U . S . military involvement and a continued relationship with the Chinese government cemented their roles as preferred trading partners , illustrating how the country used economic power , as well as military might , to grow its empire . <hl> 22.4 Roosevelt ’ s “ Big Stick ” Foreign Policy Learning Objectives By the end of this section , you will be able to :", "hl_sentences": "The notes were invoked barely a year later , when a group of Chinese insurgents , the Righteous and Harmonious Fists — also known as the Boxer Rebellion ( 1899 ) — fought to expel all western nations and their influences from China ( Figure 22.13 ) . The United States , along with Great Britain and Germany , sent over two thousand troops to withstand the rebellion . The troops signified American commitment to the territorial integrity of China , albeit one flooded with American products . However , for nearly half a century , U . S . military involvement and a continued relationship with the Chinese government cemented their roles as preferred trading partners , illustrating how the country used economic power , as well as military might , to grow its empire .", "question": { "cloze_format": "The Boxer Rebellion strengthen American ties with China by ___.", "normal_format": "How did the Boxer Rebellion strengthen American ties with China?", "question_choices": [ "The United States supported the rebels and gained their support.", "The United States provided troops to fight the rebels.", "The United States sent arms and financial support to the Chinese government.", "The United States thwarted attempts by Great Britain and Germany to fortify the rebels." ], "question_id": "fs-idp139432928", "question_text": "How did the Boxer Rebellion strengthen American ties with China?" }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 3, "ans_text": "They felt that Roosevelt’s deal offered too little money." }, "bloom": null, "hl_context": "<hl> Upon becoming president in 1901 , Roosevelt was determined to succeed where others had failed . <hl> <hl> Following the advice that Mahan set forth in his book The Influence of Seapower upon History , he sought to achieve the construction of a canal across Central America , primarily for military reasons associated with empire , but also for international trade considerations . <hl> The most strategic point for the construction was across the fifty-mile isthmus of Panama , which , at the turn of the century , was part of the nation of Colombia . Roosevelt negotiated with the government of Colombia , sometimes threatening to take the project away and build through Nicaragua , until Colombia agreed to a treaty that would grant the United States a lease on the land across Panama in exchange for a payment of $ 10 million and an additional $ 250,000 annual rental fee . The matter was far from settled , however . <hl> The Colombian people were outraged over the loss of their land to the United States , and saw the payment as far too low . <hl> Influenced by the public outcry , the Colombian Senate rejected the treaty and informed Roosevelt there would be no canal .", "hl_sentences": "Upon becoming president in 1901 , Roosevelt was determined to succeed where others had failed . Following the advice that Mahan set forth in his book The Influence of Seapower upon History , he sought to achieve the construction of a canal across Central America , primarily for military reasons associated with empire , but also for international trade considerations . The Colombian people were outraged over the loss of their land to the United States , and saw the payment as far too low .", "question": { "cloze_format": "Columbia reacted to the United States' proposal to construct a canal trough Central America by ___.", "normal_format": "How did Colombia react to the United States’ proposal to construct a canal through Central America?", "question_choices": [ "They preferred to build such a canal themselves.", "They preferred that no canal be built at all.", "They agreed to sell land to the United States to build the canal, but in a less advantageous location than the Panamanians.", "They felt that Roosevelt’s deal offered too little money." ], "question_id": "fs-idm248095600", "question_text": "How did Colombia react to the United States’ proposal to construct a canal through Central America?" }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 1, "ans_text": "B" }, "bloom": null, "hl_context": "<hl> Roosevelt articulated this seeming double standard in a 1904 address before Congress , in a speech that became known as the Roosevelt Corollary . <hl> The Roosevelt Corollary was based on the original Monroe Doctrine of the early nineteenth century , which warned European nations of the consequences of their interference in the Caribbean . <hl> In this addition , Roosevelt states that the United States would use military force “ as an international police power ” to correct any “ chronic wrongdoing ” by any Latin American nation that might threaten stability in the region . <hl> <hl> Unlike the Monroe Doctrine , which proclaimed an American policy of noninterference with its neighbors ’ affairs , the Roosevelt Corollary loudly proclaimed the right and obligation of the United States to involve itself whenever necessary . <hl>", "hl_sentences": "Roosevelt articulated this seeming double standard in a 1904 address before Congress , in a speech that became known as the Roosevelt Corollary . In this addition , Roosevelt states that the United States would use military force “ as an international police power ” to correct any “ chronic wrongdoing ” by any Latin American nation that might threaten stability in the region . Unlike the Monroe Doctrine , which proclaimed an American policy of noninterference with its neighbors ’ affairs , the Roosevelt Corollary loudly proclaimed the right and obligation of the United States to involve itself whenever necessary .", "question": { "cloze_format": "With the Roosevelt Corollary, Roosevelt sought to establish ________.", "normal_format": "With the Roosevelt Corollary, what did Roosevelt seek to establish?", "question_choices": [ "the consequences for any European nation that involved itself in Latin American affairs", "the right of the United States to involve itself in Latin American affairs whenever necessary", "the idea that Latin America was free and independent from foreign intervention", "the need for further colonization efforts in the Western Hemisphere" ], "question_id": "fs-idm203733616", "question_text": "With the Roosevelt Corollary, Roosevelt sought to establish ________." }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 1, "ans_text": "B" }, "bloom": null, "hl_context": "<hl> Of key interest to Taft was the debt that several Central American nations still owed to various countries in Europe . <hl> <hl> Fearing that the debt holders might use the monies owed as leverage to use military intervention in the Western Hemisphere , Taft moved quickly to pay off these debts with U . S . dollars . <hl> Of course , this move made the Central American countries indebted to the United States , a situation that not all nations wanted . When a Central American nation resisted this arrangement , however , Taft responded with military force to achieve the objective . This occurred in Nicaragua when the country refused to accept American loans to pay off its debt to Great Britain . Taft sent a warship with marines to the region to pressure the government to agree . Similarly , when Mexico considered the idea of allowing a Japanese corporation to gain significant land and economic advantages in its country , Taft urged Congress to pass the Lodge Corollary , an addendum to the Roosevelt Corollary , stating that no foreign corporation — other than American ones — could obtain strategic lands in the Western Hemisphere .", "hl_sentences": "Of key interest to Taft was the debt that several Central American nations still owed to various countries in Europe . Fearing that the debt holders might use the monies owed as leverage to use military intervention in the Western Hemisphere , Taft moved quickly to pay off these debts with U . S . dollars .", "question": { "cloze_format": "Some Central American nations object to Taft's paying off their debt to Europe with U.S. dollars ___.", "normal_format": "Why did some Central American nations object to Taft’s paying off their debt to Europe with U.S. dollars?", "question_choices": [ "because American currency wasn’t worth as much as local currencies", "because they felt it gave the United States too much leverage", "because they were forced to give land grants to the United States in return", "because they wanted Asian countries to pay off their debts instead" ], "question_id": "fs-idp9821520", "question_text": "Why did some Central American nations object to Taft’s paying off their debt to Europe with U.S. dollars?" }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 0, "ans_text": "Mexico and Japan" }, "bloom": null, "hl_context": "Taft ’ s policies , although not as based on military aggression as his predecessors , did create difficulties for the United States , both at the time and in the future . Central America ’ s indebtedness would create economic concerns for decades to come , as well as foster nationalist movements in countries resentful of American ’ s interference . <hl> In Asia , Taft ’ s efforts to mediate between China and Japan served only to heighten tensions between Japan and the United States . <hl> <hl> Furthermore , it did not succeed in creating a balance of power , as Japan ’ s reaction was to further consolidate its power and reach throughout the region . <hl> Of key interest to Taft was the debt that several Central American nations still owed to various countries in Europe . Fearing that the debt holders might use the monies owed as leverage to use military intervention in the Western Hemisphere , Taft moved quickly to pay off these debts with U . S . dollars . Of course , this move made the Central American countries indebted to the United States , a situation that not all nations wanted . When a Central American nation resisted this arrangement , however , Taft responded with military force to achieve the objective . This occurred in Nicaragua when the country refused to accept American loans to pay off its debt to Great Britain . Taft sent a warship with marines to the region to pressure the government to agree . <hl> Similarly , when Mexico considered the idea of allowing a Japanese corporation to gain significant land and economic advantages in its country , Taft urged Congress to pass the Lodge Corollary , an addendum to the Roosevelt Corollary , stating that no foreign corporation — other than American ones — could obtain strategic lands in the Western Hemisphere . <hl>", "hl_sentences": "In Asia , Taft ’ s efforts to mediate between China and Japan served only to heighten tensions between Japan and the United States . Furthermore , it did not succeed in creating a balance of power , as Japan ’ s reaction was to further consolidate its power and reach throughout the region . Similarly , when Mexico considered the idea of allowing a Japanese corporation to gain significant land and economic advantages in its country , Taft urged Congress to pass the Lodge Corollary , an addendum to the Roosevelt Corollary , stating that no foreign corporation — other than American ones — could obtain strategic lands in the Western Hemisphere .", "question": { "cloze_format": "___ and ___ were engaged in a negatiation that the Lodge Corollary disallowed.", "normal_format": "What two countries were engaged in a negotiation that the Lodge Corollary disallowed?", "question_choices": [ "Mexico and Japan", "Nicaragua and France", "Colombia and Japan", "Mexico and Spain" ], "question_id": "fs-idp9182848", "question_text": "What two countries were engaged in a negotiation that the Lodge Corollary disallowed?" }, "references_are_paraphrase": null } ]
22
22.1 Turner, Mahan, and the Roots of Empire Learning Objectives By the end of this section, you will be able to: Explain the evolution of American interest in foreign affairs from the end of the Civil War through the early 1890s Identify the contributions of Frederick Jackson Turner and Alfred Thayer Mahan to the conscious creation of an American empire During the time of Reconstruction, the U.S. government showed no significant initiative in foreign affairs. Western expansion and the goal of Manifest Destiny still held the country’s attention, and American missionaries proselytized as far abroad as China, India, the Korean Peninsula, and Africa, but reconstruction efforts took up most of the nation’s resources. As the century came to a close, however, a variety of factors, from the closing of the American frontier to the country’s increased industrial production, led the United States to look beyond its borders. Countries in Europe were building their empires through global power and trade, and the United States did not want to be left behind. AMERICA’S LIMITED BUT AGGRESSIVE PUSH OUTWARD On the eve of the Civil War, the country lacked the means to establish a strong position in international diplomacy. As of 1865, the U.S. State Department had barely sixty employees and no ambassadors representing American interests abroad. Instead, only two dozen American foreign ministers were located in key countries, and those often gained their positions not through diplomatic skills or expertise in foreign affairs but through bribes. Further limiting American potential for foreign impact was the fact that a strong international presence required a strong military—specifically a navy—which the United States, after the Civil War, was in no position to maintain. Additionally, as late as 1890, with the U.S. Navy significantly reduced in size, a majority of vessels were classified as “Old Navy,” meaning a mixture of iron hulled and wholly wooden ships. While the navy had introduced the first all-steel, triple-hulled steam engine vessels seven years earlier, they had only thirteen of them in operation by 1890. Despite such widespread isolationist impulses and the sheer inability to maintain a strong international position, the United States moved ahead sporadically with a modest foreign policy agenda in the three decades following the Civil War. Secretary of State William Seward, who held that position from 1861 through 1869, sought to extend American political and commercial influence in both Asia and Latin America. He pursued these goals through a variety of actions. A treaty with Nicaragua set the early course for the future construction of a canal across Central America. He also pushed through the annexation of the Midway Islands in the Pacific Ocean, which subsequently opened a more stable route to Asian markets. In frequent conversations with President Lincoln, among others, Seward openly spoke of his desire to obtain British Columbia, the Hawaiian Islands, portions of the Dominican Republic, Cuba, and other territories. He explained his motives to a Boston audience in 1867, when he professed his intention to give the United States “control of the world.” Most notably, in 1867, Seward obtained the Alaskan Territory from Russia for a purchase price of $7.2 million. Fearing future loss of the territory through military conflict, as well as desiring to create challenges for Great Britain (which they had fought in the Crimean War), Russia had happily accepted the American purchase offer. In the United States, several newspaper editors openly questioned the purchase and labeled it “ Seward’s Folly ” ( Figure 22.3 ). They highlighted the lack of Americans to populate the vast region and lamented the challenges in attempting to govern the native peoples in that territory. Only if gold were to be found, the editors decried, would the secretive purchase be justified. That is exactly what happened. Seward’s purchase added an enormous territory to the country—nearly 600,000 square miles—and also gave the United States access to the rich mineral resources of the region, including the gold that trigged the Klondike Gold Rush at the close of the century. As was the case elsewhere in the American borderlands, Alaska’s industrial development wreaked havoc on the region’s indigenous and Russian cultures. Seward’s successor as Secretary of State, Hamilton Fish, held the position from 1869 through 1877. Fish spent much of his time settling international disputes involving American interests, including claims that British assistance to the Confederates prolonged the Civil War for about two years. In these so-called Alabama claims, a U.S. senator charged that the Confederacy won a number of crucial battles with the help of one British cruiser and demanded $2 billion in British reparations. Alternatively, the United States would settle for the rights to Canada. A joint commission representing both countries eventually settled on a British payment of $15 million to the United States. In the negotiations, Fish also suggested adding the Dominican Republic as a territorial possession with a path towards statehood, as well as discussing the construction of a transoceanic canal with Colombia. Although neither negotiation ended in the desired result, they both expressed Fish’s intent to cautiously build an American empire without creating any unnecessary military entanglements in the wake of the Civil War. BUSINESS, RELIGIOUS, AND SOCIAL INTERESTS SET THE STAGE FOR EMPIRE While the United States slowly pushed outward and sought to absorb the borderlands (and the indigenous cultures that lived there), the country was also changing how it functioned. As a new industrial United States began to emerge in the 1870s, economic interests began to lead the country toward a more expansionist foreign policy. By forging new and stronger ties overseas, the United States would gain access to international markets for export, as well as better deals on the raw materials needed domestically. The concerns raised by the economic depression of the early 1890s further convinced business owners that they needed to tap into new markets, even at the risk of foreign entanglements. As a result of these growing economic pressures, American exports to other nations skyrocketed in the years following the Civil War, from $234 million in 1865 to $605 million in 1875. By 1898, on the eve of the Spanish-American War, American exports had reached a height of $1.3 billion annually. Imports over the same period also increased substantially, from $238 million in 1865 to $616 million in 1898. Such an increased investment in overseas markets in turn strengthened Americans’ interest in foreign affairs. Businesses were not the only ones seeking to expand. Religious leaders and Progressive reformers joined businesses in their growing interest in American expansion, as both sought to increase the democratic and Christian influences of the United States abroad. Imperialism and Progressivism were compatible in the minds of many reformers who thought the Progressive impulses for democracy at home translated overseas as well. Editors of such magazines as Century , Outlook , and Harper’s supported an imperialistic stance as the democratic responsibility of the United States. Several Protestant faiths formed missionary societies in the years after the Civil War, seeking to expand their reach, particularly in Asia. Influenced by such works as Reverend Josiah Strong’s Our Country: Its Possible Future and Its Present Crisis (1885), missionaries sought to spread the gospel throughout the country and abroad. Led by the American Board of Commissioners for Foreign Missions, among several other organizations, missionaries conflated Christian ethics with American virtues, and began to spread both gospels with zeal. This was particularly true among women missionaries, who composed over 60 percent of the overall missionary force. By 1870, missionaries abroad spent as much time advocating for the American version of a modern civilization as they did teaching the Bible. Social reformers of the early Progressive Era also performed work abroad that mirrored the missionaries. Many were influenced by recent scholarship on race-based intelligence and embraced the implications of social Darwinist theory that alleged inferior races were destined to poverty on account of their lower evolutionary status. While certainly not all reformers espoused a racist view of intelligence and civilization, many of these reformers believed that the Anglo-Saxon race was mentally superior to others and owed the presumed less evolved populations their stewardship and social uplift—a service the British writer Rudyard Kipling termed “the White man’s burden.” By trying to help people in less industrialized countries achieve a higher standard of living and a better understanding of the principles of democracy, reformers hoped to contribute to a noble cause, but their approach suffered from the same paternalism that hampered Progressive reforms at home. Whether reformers and missionaries worked with native communities in the borderlands such as New Mexico; in the inner cities, like the Salvation Army; or overseas, their approaches had much in common. Their good intentions and willingness to work in difficult conditions shone through in the letters and articles they wrote from the field. Often in their writing, it was clear that they felt divinely empowered to change the lives of other, less fortunate, and presumably, less enlightened, people. Whether oversees or in the urban slums, they benefitted from the same passions but expressed the same paternalism. My Story Lottie Moon, Missionary Lottie Moon was a Southern Baptist missionary who spent more than forty years living and working in China. She began in 1873 when she joined her sister in China as a missionary, teaching in a school for Chinese women. Her true passion, however, was to evangelize and minister, and she undertook a campaign to urge the Southern Baptist missionaries to allow women to work beyond the classroom. Her letter campaign back to the head of the Mission Board provided a vivid picture of life in China and exhorted the Southern Baptist women to give more generously of their money and their time. Her letters appeared frequently in religious publications, and it was her suggestion—that the week before Christmas be established as a time to donate to foreign missions—that led to the annual Christmas giving tradition. Lottie’s rhetoric caught on, and still today, the annual Christmas offering is done in her name. We had the best possible voyage over the water—good weather, no headwinds, scarcely any rolling or pitching—in short, all that reasonable people could ask. . . . I spent a week here last fall and of course feel very natural to be here again. I do so love the East and eastern life! Japan fascinated my heart and fancy four years ago, but now I honestly believe I love China the best, and actually, which is stranger still, like the Chinese best. —Charlotte “Lottie” Moon, 1877 Lottie remained in China through famines, the Boxer Rebellion , and other hardships. She fought against foot binding, a cultural tradition where girls’ feet were tightly bound to keep them from growing, and shared her personal food and money when those around her were suffering. But her primary goal was to evangelize her Christian beliefs to the people in China. She won the right to minister and personally converted hundreds of Chinese to Christianity. Lottie’s combination of moral certainty and selfless service was emblematic of the missionary zeal of the early American empire. TURNER, MAHAN, AND THE PLAN FOR EMPIRE The initial work of businesses, missionaries, and reformers set the stage by the early 1890s for advocates of an expanded foreign policy and a vision of an American empire. Following decades of an official stance of isolationism combined with relatively weak presidents who lacked the popular mandate or congressional support to undertake substantial overseas commitments, a new cadre of American leaders—many of whom were too young to fully comprehend the damage inflicted by the Civil War—assumed leadership roles. Eager to be tested in international conflict, these new leaders hoped to prove America’s might on a global stage. The Assistant Secretary of the Navy, Theodore Roosevelt, was one of these leaders who sought to expand American influence globally, and he advocated for the expansion of the U.S. Navy, which at the turn of the century was the only weapons system suitable for securing overseas expansion. Turner ( Figure 22.4 ) and naval strategist Alfred Thayer Mahan were instrumental in the country’s move toward foreign expansion, and writer Brooks Adams further dramatized the consequences of the nation’s loss of its frontier in his The Law of Civilization and Decay in 1895. As mentioned in the chapter opening, Turner announced his Frontier Thesis —that American democracy was largely formed by the American frontier—at the Chicago World’s Colombian Exposition. He noted that “for nearly three centuries the dominant fact in American life has been expansion.” He continued: “American energy will continually demand a wider field for its exercise.” Although there was no more room for these forces to proceed domestically, they would continue to find an outlet on the international stage. Turner concluded that “the demands for a vigorous foreign policy, for an interoceanic canal, for a revival of our power upon our seas, and for the extension of American influence to outlying islands and adjoining countries are indications that the forces [of expansion] will continue.” Such policies would permit Americans to find new markets. Also mindful of the mitigating influence of a frontier—in terms of easing pressure from increased immigration and population expansion in the eastern and midwestern United States—he encouraged new outlets for further population growth, whether as lands for further American settlement or to accommodate more immigrants. Turner’s thesis was enormously influential at the time but has subsequently been widely criticized by historians. Specifically, the thesis underscores the pervasive racism and disregard for the indigenous communities, cultures, and individuals in the American borderlands and beyond. While Turner provided the idea for an empire, Mahan provided the more practical guide. In his 1890 work, The Influence of Seapower upon History , he suggested three strategies that would assist the United States in both constructing and maintaining an empire. First, noting the sad state of the U.S. Navy, he called for the government to build a stronger, more powerful version. Second, he suggested establishing a network of naval bases to fuel this expanding fleet. Seward’s previous acquisition of the Midway Islands served this purpose by providing an essential naval coaling station, which was vital, as the limited reach of steamships and their dependence on coal made naval coaling stations imperative for increasing the navy’s geographic reach. Future acquisitions in the Pacific and Caribbean increased this naval supply network ( Figure 22.5 ). Finally, Mahan urged the future construction of a canal across the isthmus of Central America, which would decrease by two-thirds the time and power required to move the new navy from the Pacific to the Atlantic oceans. Heeding Mahan’s advice, the government moved quickly, passing the Naval Act of 1890, which set production levels for a new, modern fleet. By 1898, the government had succeeded in increasing the size of the U.S. Navy to an active fleet of 160 vessels, of which 114 were newly built of steel. In addition, the fleet now included six battleships, compared to zero in the previous decade. As a naval power, the country catapulted to the third strongest in world rankings by military experts, trailing only Spain and Great Britain. The United States also began to expand its influence to other Pacific Islands, most notably Samoa and Hawaii. With regard to the latter, American businessmen were most interested in the lucrative sugar industry that lay at the heart of the Hawaiian Islands’ economy. By 1890, through a series of reciprocal trade agreements, Hawaiians exported nearly all of their sugar production to the United States, tariff-free. When Queen Liliuokalani tapped into a strong anti-American resentment among native Hawaiians over the economic and political power of exploitative American sugar companies between 1891 and 1893, worried businessmen worked with the American minister to Hawaii, John Stevens, to stage a quick, armed revolt to counter her efforts and seize the islands as an American protectorate ( Figure 22.6 ). Following five more years of political wrangling, the United States annexed Hawaii in 1898, during the Spanish-American War. The United States had similar strategic interests in the Samoan Islands of the South Pacific, most notably, access to the naval refueling station at Pago Pago where American merchant vessels as well as naval ships could take on food, fuel, and supplies. In 1899, in an effort to mitigate other foreign interests and still protect their own, the United States joined Great Britain and Germany in a three-party protectorate over the islands, which assured American access to the strategic ports located there. 22.2 The Spanish-American War and Overseas Empire Learning Objectives By the end of this section, you will be able to: Explain the origins and events of the Spanish-American War Analyze the different American opinions on empire at the conclusion of the Spanish-American War Describe how the Spanish-American War intersected with other American expansions to solidify the nation’s new position as an empire The Spanish-American War was the first significant international military conflict for the United States since its war against Mexico in 1846; it came to represent a critical milestone in the country’s development as an empire. Ostensibly about the rights of Cuban rebels to fight for freedom from Spain, the war had, for the United States at least, a far greater importance in the country’s desire to expand its global reach. The Spanish-American War was notable not only because the United States succeeded in seizing territory from another empire, but also because it caused the global community to recognize that the United States was a formidable military power. In what Secretary of State John Hay called “a splendid little war,” the United States significantly altered the balance of world power, just as the twentieth century began to unfold ( Figure 22.7 ). THE CHALLENGE OF DECLARING WAR Despite its name, the Spanish-American War had less to do with the foreign affairs between the United States and Spain than Spanish control over Cuba. Spain had dominated Central and South America since the late fifteenth century. But, by 1890, the only Spanish colonies that had not yet acquired their independence were Cuba and Puerto Rico. On several occasions prior to the war, Cuban independence fighters in the "Cuba Libre" movement had attempted unsuccessfully to end Spanish control of their lands. In 1895, a similar revolt for independence erupted in Cuba; again, Spanish forces under the command of General Valeriano Weyler repressed the insurrection. Particularly notorious was their policy of re-concentration in which Spanish troops forced rebels from the countryside into military-controlled camps in the cities, where many died from harsh conditions. As with previous uprisings, Americans were largely sympathetic to the Cuban rebels’ cause, especially as the Spanish response was notably brutal. Evoking the same rhetoric of independence with which they fought the British during the American Revolution, several people quickly rallied to the Cuban fight for freedom. Shippers and other businessmen, particularly in the sugar industry, supported American intervention to safeguard their own interests in the region. Likewise, the “Cuba Libre” movement founded by José Martí , who quickly established offices in New York and Florida, further stirred American interest in the liberation cause. The difference in this uprising, however, was that supporters saw in the renewed U.S. Navy a force that could be a strong ally for Cuba. Additionally, the late 1890s saw the height of yellow journalism , in which newspapers such as the New York Journal , led by William Randolph Hearst, and the New York World , published by Joseph Pulitzer, competed for readership with sensationalistic stories. These publishers, and many others who printed news stories for maximum drama and effect, knew that war would provide sensational copy. However, even as sensationalist news stories fanned the public’s desire to try out their new navy while supporting freedom, one key figure remained unmoved. President William McKinley, despite commanding a new, powerful navy, also recognized that the new fleet—and soldiers—were untested. Preparing for a reelection bid in 1900, McKinley did not see a potential war with Spain, acknowledged to be the most powerful naval force in the world, as a good bet. McKinley did publicly admonish Spain for its actions against the rebels, and urged Spain to find a peaceful solution in Cuba, but he remained resistant to public pressure for American military intervention. McKinley’s reticence to involve the United States changed in February 1898. He had ordered one of the newest navy battleships, the USS Maine , to drop anchor off the coast of Cuba in order to observe the situation, and to prepare to evacuate American citizens from Cuba if necessary. Just days after it arrived, on February 15, an explosion destroyed the Maine , killing over 250 American sailors ( Figure 22.8 ). Immediately, yellow journalists jumped on the headline that the explosion was the result of a Spanish attack, and that all Americans should rally to war. The newspaper battle cry quickly emerged, “Remember the Maine!” Recent examinations of the evidence of that time have led many historians to conclude that the explosion was likely an accident due to the storage of gun powder close to the very hot boilers. But in 1898, without ready evidence, the newspapers called for a war that would sell papers, and the American public rallied behind the cry. McKinley made one final effort to avoid war, when late in March, he called on Spain to end its policy of concentrating the native population in military camps in Cuba, and to formally declare Cuba’s independence. Spain refused, leaving McKinley little choice but to request a declaration of war from Congress. Congress received McKinley’s war message, and on April 19, 1898, they officially recognized Cuba’s independence and authorized McKinley to use military force to remove Spain from the island. Equally important, Congress passed the Teller Amendment to the resolution, which stated that the United States would not annex Cuba following the war, appeasing those who opposed expansionism. WAR: BRIEF AND DECISIVE The Spanish-American War lasted approximately ten weeks, and the outcome was clear: The United States triumphed in its goal of helping liberate Cuba from Spanish control. Despite the positive result, the conflict did present significant challenges to the United States military. Although the new navy was powerful, the ships were, as McKinley feared, largely untested. Similarly untested were the American soldiers. The country had fewer than thirty thousand soldiers and sailors, many of whom were unprepared to do battle with a formidable opponent. But volunteers sought to make up the difference. Over one million American men—many lacking a uniform and coming equipped with their own guns—quickly answered McKinley’s call for able-bodied men. Nearly ten thousand African American men also volunteered for service, despite the segregated conditions and additional hardships they faced, including violent uprisings at a few American bases before they departed for Cuba. The government, although grateful for the volunteer effort, was still unprepared to feed and supply such a force, and many suffered malnutrition and malaria for their sacrifice. To the surprise of the Spanish forces who saw the conflict as a clear war over Cuba, American military strategists prepared for it as a war for empire. More so than simply the liberation of Cuba and the protection of American interests in the Caribbean, military strategists sought to further Mahan’s vision of additional naval bases in the Pacific Ocean, reaching as far as mainland Asia. Such a strategy would also benefit American industrialists who sought to expand their markets into China. Just before leaving his post for volunteer service as a lieutenant colonel in the U.S. cavalry, Assistant Secretary of the Navy Theodore Roosevelt ordered navy ships to attack the Spanish fleet in the Philippines, another island chain under Spanish control. As a result, the first significant military confrontation took place not in Cuba but halfway around the world in the Philippines. Commodore George Dewey led the U.S. Navy in a decisive victory, sinking all of the Spanish ships while taking almost no American losses. Within a month, the U.S. Army landed a force to take the islands from Spain, which it succeeded in doing by mid-August 1899. The victory in Cuba took a little longer. In June, seventeen thousand American troops landed in Cuba. Although they initially met with little Spanish resistance, by early July, fierce battles ensued near the Spanish stronghold in Santiago. Most famously, Theodore Roosevelt led his Rough Riders , an all-volunteer cavalry unit made up of adventure-seeking college graduates, and veterans and cowboys from the Southwest, in a charge up Kettle Hill, next to San Juan Hill, which resulted in American forces surrounding Santiago. The victories of the Rough Riders are the best known part of the battles, but in fact, several African American regiments, made up of veteran soldiers, were instrumental to their success. The Spanish fleet made a last-ditch effort to escape to the sea but ran into an American naval blockade that resulted in total destruction, with every Spanish vessel sunk. Lacking any naval support, Spain quickly lost control of Puerto Rico as well, offering virtually no resistance to advancing American forces. By the end of July, the fighting had ended and the war was over. Despite its short duration and limited number of casualties—fewer than 350 soldiers died in combat, about 1,600 were wounded, while almost 3,000 men died from disease—the war carried enormous significance for Americans who celebrated the victory as a reconciliation between North and South. Defining American “Smoked Yankees”: Black Soldiers in the Spanish-American War The most popular image of the Spanish-American War is of Theodore Roosevelt and his Rough Riders, charging up San Juan Hill. But less well known is that the Rough Riders struggled mightily in several battles and would have sustained far more serious casualties, if not for the experienced Black veterans—over twenty-five hundred of them—who joined them in battle ( Figure 22.9 ). These soldiers, who had been fighting the Indian wars on the American frontier for many years, were instrumental in the U.S. victory in Cuba. The choice to serve in the Spanish-American War was not a simple one. Within the Black community, many spoke out both for and against involvement in the war. Many Black Americans felt that because they were not offered the true rights of citizenship it was not their burden to volunteer for war. Others, in contrast, argued that participation in the war offered an opportunity for Black Americans to prove themselves to the rest of the country. While their presence was welcomed by the military which desperately needed experienced soldiers, the Black regiments suffered racism and harsh treatment while training in the southern states before shipping off to battle. Once in Cuba, however, the “Smoked Yankees,” as the Cubans called the Black American soldiers, fought side-by-side with Roosevelt’s Rough Riders, providing crucial tactical support to some of the most important battles of the war. After the Battle of San Juan, five Black soldiers received the Medal of Honor and twenty-five others were awarded a certificate of merit. One reporter wrote that “if it had not been for the Negro cavalry, the Rough Riders would have been exterminated.” He went on to state that, having grown up in the South, he had never been fond of Black people before witnessing the battle. For some of the soldiers, their recognition made the sacrifice worthwhile. Others, however, struggled with American oppression of Cubans and Puerto Ricans, feeling kinship with the Black residents of these countries now under American rule. ESTABLISHING PEACE AND CREATING AN EMPIRE As the war closed, Spanish and American diplomats made arrangements for a peace conference in Paris. They met in October 1898, with the Spanish government committed to regaining control of the Philippines, which they felt were unjustly taken in a war that was solely about Cuban independence. While the Teller Amendment ensured freedom for Cuba, President McKinley was reluctant to relinquish the strategically useful prize of the Philippines. He certainly did not want to give the islands back to Spain, nor did he want another European power to step in to seize them. Neither the Spanish nor the Americans considered giving the islands their independence, since, with the pervasive racism and cultural stereotyping of the day, they believed the Filipino people were not capable of governing themselves. William Howard Taft, the first American governor-general to oversee the administration of the new U.S. possession, accurately captured American sentiments with his frequent reference to Filipinos as “our little brown brothers.” As the peace negotiations unfolded, Spain agreed to recognize Cuba’s independence, as well as recognize American control of Puerto Rico and Guam. McKinley insisted that the United States maintain control over the Philippines as an annexation, in return for a $20 million payment to Spain. Although Spain was reluctant, they were in no position militarily to deny the American demand. The two sides finalized the Treaty of Paris on December 10, 1898. With it came the international recognition that there was a new American empire that included the Philippines, Puerto Rico, and Guam. The American press quickly glorified the nation’s new reach, as expressed in the cartoon below, depicting the glory of the American eagle reaching from the Philippines to the Caribbean ( Figure 22.10 ). Domestically, the country was neither unified in their support of the treaty nor in the idea of the United States building an empire at all. Many prominent Americans, including Jane Addams, former President Grover Cleveland, Andrew Carnegie, Mark Twain, and Samuel Gompers, felt strongly that the country should not be pursuing an empire, and, in 1898, they formed the Anti-Imperialist League to oppose this expansionism. The reasons for their opposition were varied: Some felt that empire building went against the principles of democracy and freedom upon which the country was founded, some worried about competition from foreign workers, and some held the xenophobic viewpoint that the assimilation of other races would hurt the country. Regardless of their reasons, the group, taken together, presented a formidable challenge. As foreign treaties require a two-thirds majority in the U.S. Senate to pass, the Anti-Imperialist League’s pressure led them to a clear split, with the possibility of defeat of the treaty seeming imminent. Less than a week before the scheduled vote, however, news of a Filipino uprising against American forces reached the United States. Undecided senators were convinced of the need to maintain an American presence in the region and preempt the intervention of another European power, and the Senate formally ratified the treaty on February 6, 1899. The newly formed American empire was not immediately secure, as Filipino rebels, led by Emilio Aguinaldo ( Figure 22.11 ), fought back against American forces stationed there. The Filipinos’ war for independence lasted three years, with over four thousand American and twenty thousand Filipino combatant deaths; the civilian death toll is estimated as high as 250,000. Finally, in 1901, President McKinley appointed William Howard Taft as the civil governor of the Philippines in an effort to disengage the American military from direct confrontations with the Filipino people. Under Taft’s leadership, Americans built a new transportation infrastructure, hospitals, and schools, hoping to win over the local population. The rebels quickly lost influence, and Aguinaldo was captured by American forces and forced to swear allegiance to the United States. The Taft Commission, as it became known, continued to introduce reforms to modernize and improve daily life for the country despite pockets of resistance that continued to fight through the spring of 1902. Much of the commission’s rule centered on legislative reforms to local government structure and national agencies, with the commission offering appointments to resistance leaders in exchange for their support. The Philippines continued under American rule until they became self-governing in 1946. After the conclusion of the Spanish-American War and the successful passage of the peace treaty with Spain, the United States continued to acquire other territories. Seeking an expanded international presence, as well as control of maritime routes and naval stations, the United States grew to include Hawaii, which was granted territorial status in 1900, and Alaska, which, although purchased from Russia decades earlier, only became a recognized territory in 1912. In both cases, their status as territories granted U.S. citizenship to their residents. The Foraker Act of 1900 established Puerto Rico as an American territory with its own civil government. It was not until 1917 that Puerto Ricans were granted American citizenship. Guam and Samoa, which had been taken as part of the war, remained under the control of the U.S. Navy. Cuba, which after the war was technically a free country, adopted a constitution based on the U.S. Constitution. While the Teller Amendment had prohibited the United States from annexing the country, a subsequent amendment, the Platt Amendment, secured the right of the United States to interfere in Cuban affairs if threats to a stable government emerged. The Platt Amendment also guaranteed the United States its own naval and coaling station on the island’s southern Guantanamo Bay and prohibited Cuba from making treaties with other countries that might eventually threaten their independence. While Cuba remained an independent nation on paper, in all practicality the United States governed Cuba’s foreign policy and economic agreements. 22.3 Economic Imperialism in East Asia Learning Objectives By the end of this section, you will be able to: Explain how economic power helped to expand America’s empire in China Describe how the foreign partitioning of China in the last decade of the nineteenth century influenced American policy While American forays into empire building began with military action, the country concurrently grew its scope and influence through other methods as well. In particular, the United States used its economic and industrial capacity to add to its empire, as can be seen in a study of the China market and the “Open Door notes” discussed below. WHY CHINA? Since the days of Christopher Columbus’s westward journey to seek a new route to the East Indies (essentially India and China, but loosely defined as all of Southeast Asia), many westerners have dreamt of the elusive “China Market.” With the defeat of the Spanish navy in the Atlantic and Pacific, and specifically with the addition of the Philippines as a base for American ports and coaling stations, the United States was ready to try and make the myth a reality. Although China originally accounted for only a small percentage of American foreign trade, captains of American industry dreamed of a vast market of Asian customers desperate for manufactured goods they could not yet produce in large quantities for themselves. American businesses were not alone in seeing the opportunities. Other countries—including Japan, Russia, Great Britain, France, and Germany—also hoped to make inroads in China. Previous treaties between Great Britain and China in 1842 and 1844 during the Opium Wars, when the British Empire militarily coerced the Chinese empire to accept the import of Indian opium in exchange for its tea, had forced an “open door” policy on China, in which all foreign nations had free and equal access to Chinese ports. This was at a time when Great Britain maintained the strongest economic relationship with China; however, other western nations used the new arrangement to send Christian missionaries, who began to work across inland China. Following the Sino-Japanese War of 1894–1895 over China’s claims to Korea, western countries hoped to exercise even greater influence in the region. By 1897, Germany had obtained exclusive mining rights in northern coastal China as reparations for the murder of two German missionaries. In 1898, Russia obtained permission to build a railroad across northeastern Manchuria. One by one, each country carved out their own sphere of influence , where they could control markets through tariffs and transportation, and thus ensure their share of the Chinese market. Alarmed by the pace at which foreign powers further divided China into pseudo-territories, and worried that they had no significant piece for themselves, the United States government intervened. In contrast to European nations, however, American businesses wanted the whole market, not just a share of it. They wanted to do business in China with no artificially constructed spheres or boundaries to limit the extent of their trade, but without the territorial entanglements or legislative responsibilities that anti-imperialists opposed. With the blessing and assistance of Secretary of State John Hay, several American businessmen created the American Asiatic Association in 1896 to pursue greater trade opportunities in China. THE OPEN DOOR NOTES In 1899, Secretary of State Hay made a bold move to acquire China’s vast markets for American access by introducing Open Door notes , a series of circular notes that Hay himself drafted as an expression of U.S. interests in the region and sent to the other competing powers ( Figure 22.12 ). These notes, if agreed to by the other five nations maintaining spheres of influences in China, would erase all spheres and essentially open all doors to free trade, with no special tariffs or transportation controls that would give unfair advantages to one country over another. Specifically, the notes required that all countries agree to maintain free access to all treaty ports in China, to pay railroad charges and harbor fees (with no special access), and that only China would be permitted to collect any taxes on trade within its borders. While on paper, the Open Door notes would offer equal access to all, the reality was that it greatly favored the United States. Free trade in China would give American businesses the ultimate advantage, as American companies were producing higher-quality goods than other countries, and were doing so more efficiently and less expensively. The “open doors” would flood the Chinese market with American goods, virtually squeezing other countries out of the market. Although the foreign ministers of the other five nations sent half-hearted replies on behalf of their respective governments, with some outright denying the viability of the notes, Hay proclaimed them the new official policy on China, and American goods were unleashed throughout the nation. China was quite welcoming of the notes, as they also stressed the U.S. commitment to preserving the Chinese government and territorial integrity. The notes were invoked barely a year later, when a group of Chinese insurgents, the Righteous and Harmonious Fists—also known as the Boxer Rebellion (1899)—fought to expel all western nations and their influences from China ( Figure 22.13 ). The United States, along with Great Britain and Germany, sent over two thousand troops to withstand the rebellion. The troops signified American commitment to the territorial integrity of China, albeit one flooded with American products. Despite subsequent efforts, by Japan in particular, to undermine Chinese authority in 1915 and again during the Manchurian crisis of 1931, the United States remained resolute in defense of the open door principles through World War II. Only when China turned to communism in 1949 following an intense civil war did the principle become relatively meaningless. However, for nearly half a century, U.S. military involvement and a continued relationship with the Chinese government cemented their roles as preferred trading partners, illustrating how the country used economic power, as well as military might, to grow its empire. 22.4 Roosevelt’s “Big Stick” Foreign Policy Learning Objectives By the end of this section, you will be able to: Explain the meaning of “big stick” foreign policy Describe Theodore Roosevelt’s use of the “big stick” to construct the Panama Canal Explain the role of the United States in ending the Russo-Japanese War While President McKinley ushered in the era of the American empire through military strength and economic coercion, his successor, Theodore Roosevelt, established a new foreign policy approach, allegedly based on a favorite African proverb, “speak softly, and carry a big stick, and you will go far” ( Figure 22.14 ). At the crux of his foreign policy was a thinly veiled threat. Roosevelt believed that in light of the country’s recent military successes, it was unnecessary to use force to achieve foreign policy goals, so long as the military could threaten force. This rationale also rested on the young president’s philosophy, which he termed the “strenuous life,” and that prized challenges overseas as opportunities to instill American men with the resolve and vigor they allegedly had once acquired in the Trans-Mississippi West. Roosevelt believed that while the coercive power wielded by the United States could be harmful in the wrong hands, the Western Hemisphere’s best interests were also the best interests of the United States. He felt, in short, that the United States had the right and the obligation to be the policeman of the hemisphere. This belief, and his strategy of “speaking softly and carrying a big stick,” shaped much of Roosevelt’s foreign policy. THE CONSTRUCTION OF THE PANAMA CANAL As early as the mid-sixteenth century, interest in a canal across the Central American isthmus began to take root, primarily out of trade interests. The subsequent discovery of gold in California in 1848 further spurred interest in connecting the Atlantic and Pacific Oceans, and led to the construction of the Panama Railway, which began operations in 1855. Several attempts by France to construct a canal between 1881 and 1894 failed due to a combination of financial crises and health hazards, including malaria and yellow fever , which led to the deaths of thousands of French workers. Upon becoming president in 1901, Roosevelt was determined to succeed where others had failed. Following the advice that Mahan set forth in his book The Influence of Seapower upon History , he sought to achieve the construction of a canal across Central America, primarily for military reasons associated with empire, but also for international trade considerations. The most strategic point for the construction was across the fifty-mile isthmus of Panama, which, at the turn of the century, was part of the nation of Colombia. Roosevelt negotiated with the government of Colombia, sometimes threatening to take the project away and build through Nicaragua, until Colombia agreed to a treaty that would grant the United States a lease on the land across Panama in exchange for a payment of $10 million and an additional $250,000 annual rental fee. The matter was far from settled, however. The Colombian people were outraged over the loss of their land to the United States, and saw the payment as far too low. Influenced by the public outcry, the Colombian Senate rejected the treaty and informed Roosevelt there would be no canal. Undaunted, Roosevelt chose to now wield the “big stick.” In comments to journalists, he made it clear that the United States would strongly support the Panamanian people should they choose to revolt against Colombia and form their own nation. In November 1903, he even sent American battleships to the coast of Colombia, ostensibly for practice maneuvers, as the Panamanian revolution unfolded. The warships effectively blocked Colombia from moving additional troops into the region to quell the growing Panamanian uprising. Within a week, Roosevelt immediately recognized the new country of Panama, welcoming them to the world community and offering them the same terms—$10 million plus the annual $250,000 rental fee—he had previously offered Colombia. Following the successful revolution, Panama became an American protectorate, and remained so until 1939. Once the Panamanian victory was secured, with American support, construction on the canal began in May 1904. For the first year of operations, the United States worked primarily to build adequate housing, cafeterias, warehouses, machine shops, and other elements of infrastructure that previous French efforts had failed to consider. Most importantly, the introduction of fumigation systems and mosquito nets following Dr. Walter Reed’s discovery of the role of mosquitoes in the spread of malaria and yellow fever reduced the death rate and restored the fledgling morale among workers and American-born supervisors. At the same time, a new wave of American engineers planned for the construction of the canal. Even though they decided to build a lock-system rather than a sea-level canal, workers still had to excavate over 170 million cubic yards of earth with the use of over one hundred new rail-mounted steam shovels ( Figure 22.15 ). Excited by the work, Roosevelt became the first sitting U.S. president to conduct an official international trip. He traveled to Panama where he visited the construction site, taking a turn at the steam shovel and removing dirt. The canal opened in 1914, permanently changing world trade and military defense patterns. THE ROOSEVELT COROLLARY With the construction of the canal now underway, Roosevelt next wanted to send a clear message to the rest of the world—and in particular to his European counterparts—that the colonization of the Western Hemisphere had now ended, and their interference in the countries there would no longer be tolerated. At the same time, he sent a message to his counterparts in Central and South America, should the United States see problems erupt in the region, that it would intervene in order to maintain peace and stability throughout the hemisphere. Roosevelt articulated this seeming double standard in a 1904 address before Congress, in a speech that became known as the Roosevelt Corollary . The Roosevelt Corollary was based on the original Monroe Doctrine of the early nineteenth century, which warned European nations of the consequences of their interference in the Caribbean. In this addition, Roosevelt states that the United States would use military force “as an international police power” to correct any “chronic wrongdoing” by any Latin American nation that might threaten stability in the region. Unlike the Monroe Doctrine, which proclaimed an American policy of noninterference with its neighbors’ affairs, the Roosevelt Corollary loudly proclaimed the right and obligation of the United States to involve itself whenever necessary. Roosevelt immediately began to put the new corollary to work. He used it to establish protectorates over Cuba and Panama, as well as to direct the United States to manage the Dominican Republic’s custom service revenues. Despite growing resentment from neighboring countries over American intervention in their internal affairs, as well as European concerns from afar, knowledge of Roosevelt’s previous actions in Colombia concerning acquisition of land upon which to build the Panama Canal left many fearful of American reprisals should they resist. Eventually, Presidents Herbert Hoover and Franklin Roosevelt softened American rhetoric regarding U.S. domination of the Western Hemisphere, with the latter proclaiming a new “Good Neighbor Policy” that renounced American intervention in other nations’ affairs. However, subsequent presidents would continue to reference aspects of the Roosevelt Corollary to justify American involvement in Haiti, Nicaragua, and other nations throughout the twentieth century. The map below ( Figure 22.16 ) shows the widespread effects of Roosevelt’s policies throughout Latin America. Defining American The Roosevelt Corollary and Its Impact In 1904, Roosevelt put the United States in the role of the “police power” of the Western Hemisphere and set a course for the U.S. relationship with Central and Latin America that played out over the next several decades. He did so with the Roosevelt Corollary, in which he stated: It is not true that the United States feels any land hunger or entertains any projects as regards the other nations of the Western Hemisphere save as such are for their welfare. All that this country desires is to see the neighboring countries stable, orderly, and prosperous. Any country whose people conduct themselves well can count upon our hearty friendship. . . . Chronic wrongdoing, or an impotence which results in a general loosening of the ties of civilized society, may in America, as elsewhere, require intervention by some civilized nation, and in the Western Hemisphere the adherence of the United States to the Monroe Doctrine may force the United States, however, reluctantly, in flagrant cases of such wrongdoing or impotence, to the exercise of an international police power.” In the twenty years after he made this statement, the United States would use military force in Latin America over a dozen times. The Roosevelt Corollary was used as a rationale for American involvement in the Dominican Republic, Nicaragua, Haiti, and other Latin American countries, straining relations between Central America and its dominant neighbor to the north throughout the twentieth century. AMERICAN INTERVENTION IN THE RUSSO-JAPANESE WAR Although he supported the Open Door notes as an excellent economic policy in China, Roosevelt lamented the fact that the United States had no strong military presence in the region to enforce it. Clearly, without a military presence there, he could not as easily use his “big stick” threat credibly to achieve his foreign policy goals. As a result, when conflicts did arise on the other side of the Pacific, Roosevelt adopted a policy of maintaining a balance of power among the nations there. This was particularly evident when the Russo-Japanese War erupted in 1904. In 1904, angered by the massing of Russian troops along the Manchurian border, and the threat it represented to the region, Japan launched a surprise naval attack upon the Russian fleet. Initially, Roosevelt supported the Japanese position. However, when the Japanese fleet quickly achieved victory after victory, Roosevelt grew concerned over the growth of Japanese influence in the region and the continued threat that it represented to China and American access to those markets ( Figure 22.17 ). Wishing to maintain the aforementioned balance of power, in 1905, Roosevelt arranged for diplomats from both nations to attend a secret peace conference in Portsmouth, New Hampshire. The resultant negotiations secured peace in the region, with Japan gaining control over Korea, several former Russian bases in Manchuria, and the southern half of Sakhalin Island. These negotiations also garnered the Nobel Peace Prize for Roosevelt, the first American to receive the award. When Japan later exercised its authority over its gains by forcing American business interests out of Manchuria in 1906–1907, Roosevelt felt he needed to invoke his “big stick” foreign policy, even though the distance was great. He did so by sending the U.S. Great White Fleet on maneuvers in the western Pacific Ocean as a show of force from December 1907 through February 1909. Publicly described as a goodwill tour, the message to the Japanese government regarding American interests was equally clear. Subsequent negotiations reinforced the Open Door policy throughout China and the rest of Asia. Roosevelt had, by both the judicious use of the “big stick” and his strategy of maintaining a balance of power, kept U.S. interests in Asia well protected. 22.5 Taft’s “Dollar Diplomacy” Learning Objectives By the end of this section, you will be able to: Explain how William Howard Taft used American economic power to protect the nation’s interests in its new empire When William Howard Taft became president in 1909, he chose to adapt Roosevelt’s foreign policy philosophy to one that reflected American economic power at the time. In what became known as “ dollar diplomacy ,” Taft announced his decision to “substitute dollars for bullets” in an effort to use foreign policy to secure markets and opportunities for American businessmen ( Figure 22.18 ). Not unlike Roosevelt’s threat of force, Taft used the threat of American economic clout to coerce countries into agreements to benefit the United States. Of key interest to Taft was the debt that several Central American nations still owed to various countries in Europe. Fearing that the debt holders might use the monies owed as leverage to use military intervention in the Western Hemisphere, Taft moved quickly to pay off these debts with U.S. dollars. Of course, this move made the Central American countries indebted to the United States, a situation that not all nations wanted. When a Central American nation resisted this arrangement, however, Taft responded with military force to achieve the objective. This occurred in Nicaragua when the country refused to accept American loans to pay off its debt to Great Britain. Taft sent a warship with marines to the region to pressure the government to agree. Similarly, when Mexico considered the idea of allowing a Japanese corporation to gain significant land and economic advantages in its country, Taft urged Congress to pass the Lodge Corollary, an addendum to the Roosevelt Corollary, stating that no foreign corporation—other than American ones—could obtain strategic lands in the Western Hemisphere. In Asia, Taft’s policies also followed those of Theodore Roosevelt. He attempted to bolster China’s ability to withstand Japanese interference and thereby maintain a balance of power in the region. Initially, he experienced tremendous success in working with the Chinese government to further develop the railroad industry in that country through arranging international financing. However, efforts to expand the Open Door policy deeper into Manchuria met with resistance from Russia and Japan, exposing the limits of the American government’s influence and knowledge about the intricacies of diplomacy. As a result, he reorganized the U.S. State Department to create geographical divisions (such as the Far East Division, the Latin American Division, etc.) in order to develop greater foreign policy expertise in each area. Taft’s policies, although not as based on military aggression as his predecessors, did create difficulties for the United States, both at the time and in the future. Central America’s indebtedness would create economic concerns for decades to come, as well as foster nationalist movements in countries resentful of American’s interference. In Asia, Taft’s efforts to mediate between China and Japan served only to heighten tensions between Japan and the United States. Furthermore, it did not succeed in creating a balance of power, as Japan’s reaction was to further consolidate its power and reach throughout the region. As Taft’s presidency came to a close in early 1913, the United States was firmly entrenched on its path towards empire. The world perceived the United States as the predominant power of the Western Hemisphere—a perception that few nations would challenge until the Soviet Union during the Cold War era. Likewise, the United States had clearly marked its interests in Asia, although it was still searching for an adequate approach to guard and foster them. The development of an American empire had introduced with it several new approaches to American foreign policy, from military intervention to economic coercion to the mere threat of force. The playing field would change one year later in 1914 when the United States witnessed the unfolding of World War I, or “the Great War.” A new president would attempt to adopt a new approach to diplomacy—one that was well-intentioned but at times impractical. Despite Woodrow Wilson’s best efforts to the contrary, the United States would be drawn into the conflict and subsequently attempt to reshape the world order as a result.
biology
Chapter Outline 26.1 Evolution of Seed Plants 26.2 Gymnosperms 26.3 Angiosperms 26.4 The Role of Seed Plants Introduction The lush palms on tropical shorelines do not depend on water for the dispersal of their pollen, fertilization, or the survival of the zygote—unlike mosses, liverworts, and ferns of the terrain. Seed plants, such as palms, have broken free from the need to rely on water for their reproductive needs. They play an integral role in all aspects of life on the planet, shaping the physical terrain, influencing the climate, and maintaining life as we know it. For millennia, human societies have depended on seed plants for nutrition and medicinal compounds: and more recently, for industrial by-products, such as timber and paper, dyes, and textiles. Palms provide materials including rattans, oils, and dates. Wheat is grown to feed both human and animal populations. The fruit of the cotton boll flower is harvested as a boll, with its fibers transformed into clothing or pulp for paper. The showy opium poppy is valued both as an ornamental flower and as a source of potent opiate compounds.
[ { "answer": { "ans_choice": 3, "ans_text": "all heterosporous." }, "bloom": null, "hl_context": "In seed plants , the evolutionary trend led to a dominant sporophyte generation , and at the same time , a systematic reduction in the size of the gametophyte : from a conspicuous structure to a microscopic cluster of cells enclosed in the tissues of the sporophyte . <hl> Whereas lower vascular plants , such as club mosses and ferns , are mostly homosporous ( produce only one type of spore ) , all seed plants , or spermatophytes , are heterosporous . <hl> They form two types of spores : megaspores ( female ) and microspores ( male ) . Megaspores develop into female gametophytes that produce eggs , and microspores mature into male gametophytes that generate sperm . Because the gametophytes mature within the spores , they are not free-living , as are the gametophytes of other seedless vascular plants . Heterosporous seedless plants are seen as the evolutionary forerunners of seed plants .", "hl_sentences": "Whereas lower vascular plants , such as club mosses and ferns , are mostly homosporous ( produce only one type of spore ) , all seed plants , or spermatophytes , are heterosporous .", "question": { "cloze_format": "Seed plants are ________.", "normal_format": "Which of the following is correct about seed plants?", "question_choices": [ "all homosporous.", "mostly homosporous with some heterosporous.", "mostly heterosporous with some homosporous.", "all heterosporous." ], "question_id": "fs-idp152109776", "question_text": "Seed plants are ________." }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 2, "ans_text": "Triassic" }, "bloom": null, "hl_context": "Seeds and pollen — two critical adaptations to drought , and to reproduction that doesn ’ t require water — distinguish seed plants from other ( seedless ) vascular plants . Both adaptations were required for the colonization of land begun by the bryophytes and their ancestors . Fossils place the earliest distinct seed plants at about 350 million years ago . The first reliable record of gymnosperms dates their appearance to the Pennsylvanian period , about 319 million years ago ( Figure 26.2 ) . Gymnosperms were preceded by progymnosperms , the first naked seed plants , which arose about 380 million years ago . Progymnosperms were a transitional group of plants that superficially resembled conifers ( cone bearers ) because they produced wood from the secondary growth of the vascular tissues ; however , they still reproduced like ferns , releasing spores into the environment . <hl> Gymnosperms dominated the landscape in the early ( Triassic ) and middle ( Jurassic ) Mesozoic era . <hl> Angiosperms surpassed gymnosperms by the middle of the Cretaceous ( about 100 million years ago ) in the late Mesozoic era , and today are the most abundant plant group in most terrestrial biomes .", "hl_sentences": "Gymnosperms dominated the landscape in the early ( Triassic ) and middle ( Jurassic ) Mesozoic era .", "question": { "cloze_format": "The geological periods in which gymnosperms would dominate the landscape is the ___.", "normal_format": "In which of the following geological periods would gymnosperms dominate the landscape?", "question_choices": [ "Carboniferous", "Permian", "Triassic", "Eocene (present)" ], "question_id": "fs-idm50302448", "question_text": "In which of the following geological periods would gymnosperms dominate the landscape?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 0, "ans_text": "seed" }, "bloom": "3", "hl_context": "<hl> Following fertilization of the egg , the ovule grows into a seed . <hl> <hl> The surrounding tissues of the ovary thicken , developing into a fruit that will protect the seed and often ensure its dispersal over a wide geographic range . <hl> Not all fruits develop from an ovary ; such structures are “ false fruits . ” Like flowers , fruit can vary tremendously in appearance , size , smell , and taste . Tomatoes , walnut shells and avocados are all examples of fruit . <hl> As with pollen and seeds , fruits also act as agents of dispersal . <hl> Some may be carried away by the wind . Many attract animals that will eat the fruit and pass the seeds through their digestive systems , then deposit the seeds in another location . Cockleburs are covered with stiff , hooked spines that can hook into fur ( or clothing ) and hitch a ride on an animal for long distances . The cockleburs that clung to the velvet trousers of an enterprising Swiss hiker , George de Mestral , inspired his invention of the loop and hook fastener he named Velcro .", "hl_sentences": "Following fertilization of the egg , the ovule grows into a seed . The surrounding tissues of the ovary thicken , developing into a fruit that will protect the seed and often ensure its dispersal over a wide geographic range . As with pollen and seeds , fruits also act as agents of dispersal .", "question": { "cloze_format": "The ___ structure widens the geographic range of a species and is an agent of dispersal.", "normal_format": "Which of the following structures widens the geographic range of a species and is an agent of dispersal?", "question_choices": [ "seed", "flower", "leaf", "root" ], "question_id": "fs-idm14716480", "question_text": "Which of the following structures widens the geographic range of a species and is an agent of dispersal?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 0, "ans_text": "The plants carry exposed seeds on modified leaves." }, "bloom": null, "hl_context": "Gymnosperms , meaning “ naked seeds , ” are a diverse group of seed plants and are paraphyletic . Paraphyletic groups are those in which not all members are descendants of a single common ancestor . Their characteristics include naked seeds , separate female and male gametes , pollination by wind , and tracheids ( which transport water and solutes in the vascular system ) . <hl> Gymnosperm seeds are not enclosed in an ovary ; rather , they are exposed on cones or modified leaves . <hl> Sporophylls are specialized leaves that produce sporangia . The term strobilus ( plural = strobili ) describes a tight arrangement of sporophylls around a central stalk , as seen in cones . Some seeds are enveloped by sporophyte tissues upon maturation . The layer of sporophyte tissue that surrounds the megasporangium , and later , the embryo , is called the integument .", "hl_sentences": "Gymnosperm seeds are not enclosed in an ovary ; rather , they are exposed on cones or modified leaves .", "question": { "cloze_format": "___ is a trait that characterizes gymnosperms.", "normal_format": "Which of the following traits characterizes gymnosperms?", "question_choices": [ "The plants carry exposed seeds on modified leaves.", "Reproductive structures are located in a flower.", "After fertilization, the ovary thickens and forms a fruit.", "The gametophyte is longest phase of the life cycle." ], "question_id": "fs-idp162296688", "question_text": "Which of the following traits characterizes gymnosperms?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 3, "ans_text": "female gametophytes" }, "bloom": "3", "hl_context": "In seed plants , the evolutionary trend led to a dominant sporophyte generation , and at the same time , a systematic reduction in the size of the gametophyte : from a conspicuous structure to a microscopic cluster of cells enclosed in the tissues of the sporophyte . Whereas lower vascular plants , such as club mosses and ferns , are mostly homosporous ( produce only one type of spore ) , all seed plants , or spermatophytes , are heterosporous . <hl> They form two types of spores : megaspores ( female ) and microspores ( male ) . <hl> <hl> Megaspores develop into female gametophytes that produce eggs , and microspores mature into male gametophytes that generate sperm . <hl> Because the gametophytes mature within the spores , they are not free-living , as are the gametophytes of other seedless vascular plants . Heterosporous seedless plants are seen as the evolutionary forerunners of seed plants .", "hl_sentences": "They form two types of spores : megaspores ( female ) and microspores ( male ) . Megaspores develop into female gametophytes that produce eggs , and microspores mature into male gametophytes that generate sperm .", "question": { "cloze_format": "Megasporocytes will eventually produce ___.", "normal_format": "Megasporocytes will eventually produce which of the following?", "question_choices": [ "pollen grain", "sporophytes", "male gametophytes", "female gametophytes" ], "question_id": "fs-idm74243568", "question_text": "Megasporocytes will eventually produce which of the following?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 1, "ans_text": "1n, 2n, 1n, 2n" }, "bloom": "3", "hl_context": "<hl> Unlike bryophyte and fern spores ( which are haploid cells dependent on moisture for rapid development of gametophytes ) , seeds contain a diploid embryo that will germinate into a sporophyte . <hl> Storage tissue to sustain growth and a protective coat give seeds their superior evolutionary advantage . Several layers of hardened tissue prevent desiccation , and free reproduction from the need for a constant supply of water . Furthermore , seeds remain in a state of dormancy — induced by desiccation and the hormone abscisic acid — until conditions for growth become favorable . Whether blown by the wind , floating on water , or carried away by animals , seeds are scattered in an expanding geographic range , thus avoiding competition with the parent plant . <hl> In seed plants , the evolutionary trend led to a dominant sporophyte generation , and at the same time , a systematic reduction in the size of the gametophyte : from a conspicuous structure to a microscopic cluster of cells enclosed in the tissues of the sporophyte . <hl> <hl> Whereas lower vascular plants , such as club mosses and ferns , are mostly homosporous ( produce only one type of spore ) , all seed plants , or spermatophytes , are heterosporous . <hl> They form two types of spores : megaspores ( female ) and microspores ( male ) . Megaspores develop into female gametophytes that produce eggs , and microspores mature into male gametophytes that generate sperm . Because the gametophytes mature within the spores , they are not free-living , as are the gametophytes of other seedless vascular plants . Heterosporous seedless plants are seen as the evolutionary forerunners of seed plants .", "hl_sentences": "Unlike bryophyte and fern spores ( which are haploid cells dependent on moisture for rapid development of gametophytes ) , seeds contain a diploid embryo that will germinate into a sporophyte . In seed plants , the evolutionary trend led to a dominant sporophyte generation , and at the same time , a systematic reduction in the size of the gametophyte : from a conspicuous structure to a microscopic cluster of cells enclosed in the tissues of the sporophyte . Whereas lower vascular plants , such as club mosses and ferns , are mostly homosporous ( produce only one type of spore ) , all seed plants , or spermatophytes , are heterosporous .", "question": { "cloze_format": "The ploidy of the structures gametophyte, seed, spore, and sporophyte is ___.\n", "normal_format": "What is the ploidy of the following structures: gametophyte, seed, spore, sporophyte?", "question_choices": [ "1n, 1n, 2n, 2n", "1n, 2n, 1n, 2n", "2n, 1n, 2n, 1n", "2n, 2n, 1n, 1n" ], "question_id": "fs-idp136334272", "question_text": "What is the ploidy of the following structures: gametophyte, seed, spore, sporophyte?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 0, "ans_text": "conifer" }, "bloom": "2", "hl_context": "<hl> Conifers are the dominant phylum of gymnosperms , with the most variety of species ( Figure 26.9 ) . <hl> <hl> Most are typically tall trees that usually bear scale-like or needle-like leaves . <hl> Water evaporation from leaves is reduced by their thin shape and the thick cuticle . Snow slides easily off needle-shaped leaves , keeping the load light and decreasing breaking of branches . Adaptations to cold and dry weather explain the predominance of conifers at high altitudes and in cold climates . Conifers include familiar evergreen trees such as pines , spruces , firs , cedars , sequoias , and yews . A few species are deciduous and lose their leaves in fall . The European larch and the tamarack are examples of deciduous conifers ( Figure 26.9 c ) . Many coniferous trees are harvested for paper pulp and timber . The wood of conifers is more primitive than the wood of angiosperms ; it contains tracheids , but no vessel elements , and is therefore referred to as “ soft wood . ”", "hl_sentences": "Conifers are the dominant phylum of gymnosperms , with the most variety of species ( Figure 26.9 ) . Most are typically tall trees that usually bear scale-like or needle-like leaves .", "question": { "cloze_format": "In the northern forests of Siberia, a tall tree is most likely a ___ .", "normal_format": "A tall tree, in the northern forests of Siberia, is most likely a what?", "question_choices": [ "conifer", "cycad", "Gingko biloba", "gnetophyte" ], "question_id": "fs-idm21727008", "question_text": "In the northern forests of Siberia, a tall tree is most likely a:" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 2, "ans_text": "the sepal" }, "bloom": "2", "hl_context": "As illustrated in Figure 26.14 , styles , stigmas , and ovules constitute the female organ : the gynoecium or carpel . <hl> Flower structure is very diverse , and carpels may be singular , multiple , or fused . <hl> <hl> Multiple fused carpels comprise a pistil . <hl> <hl> The megaspores and the female gametophytes are produced and protected by the thick tissues of the carpel . <hl> <hl> A long , thin structure called a style leads from the sticky stigma , where pollen is deposited , to the ovary , enclosed in the carpel . <hl> <hl> The ovary houses one or more ovules , each of which will develop into a seed upon fertilization . <hl> <hl> The male reproductive organs , the stamens ( collectively called the androecium ) , surround the central carpel . <hl> <hl> Stamens are composed of a thin stalk called a filament and a sac-like structure called the anther . <hl> <hl> The filament supports the anther , where the microspores are produced by meiosis and develop into pollen grains . <hl>", "hl_sentences": "Flower structure is very diverse , and carpels may be singular , multiple , or fused . Multiple fused carpels comprise a pistil . The megaspores and the female gametophytes are produced and protected by the thick tissues of the carpel . A long , thin structure called a style leads from the sticky stigma , where pollen is deposited , to the ovary , enclosed in the carpel . The ovary houses one or more ovules , each of which will develop into a seed upon fertilization . The male reproductive organs , the stamens ( collectively called the androecium ) , surround the central carpel . Stamens are composed of a thin stalk called a filament and a sac-like structure called the anther . The filament supports the anther , where the microspores are produced by meiosis and develop into pollen grains .", "question": { "cloze_format": "___ is a structure in a flower that is not directly involved in reproduction.", "normal_format": "Which of the following structures in a flower is not directly involved in reproduction?", "question_choices": [ "the style", "the stamen", "the sepal", "the anther" ], "question_id": "fs-idp45858640", "question_text": "Which of the following structures in a flower is not directly involved in reproduction?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 0, "ans_text": "the anther" }, "bloom": "3", "hl_context": "As illustrated in Figure 26.14 , styles , stigmas , and ovules constitute the female organ : the gynoecium or carpel . Flower structure is very diverse , and carpels may be singular , multiple , or fused . Multiple fused carpels comprise a pistil . The megaspores and the female gametophytes are produced and protected by the thick tissues of the carpel . A long , thin structure called a style leads from the sticky stigma , where pollen is deposited , to the ovary , enclosed in the carpel . The ovary houses one or more ovules , each of which will develop into a seed upon fertilization . The male reproductive organs , the stamens ( collectively called the androecium ) , surround the central carpel . <hl> Stamens are composed of a thin stalk called a filament and a sac-like structure called the anther . <hl> <hl> The filament supports the anther , where the microspores are produced by meiosis and develop into pollen grains . <hl>", "hl_sentences": "Stamens are composed of a thin stalk called a filament and a sac-like structure called the anther . The filament supports the anther , where the microspores are produced by meiosis and develop into pollen grains .", "question": { "cloze_format": "Pollen grains develop in the structure of ___ .", "normal_format": "Pollen grains develop in which structure?", "question_choices": [ "the anther", "the stigma", "the filament", "the carpel" ], "question_id": "fs-idm38276480", "question_text": "Pollen grains develop in which structure?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 1, "ans_text": "the polar nuclei of the center cell" }, "bloom": null, "hl_context": "The ovule , sheltered within the ovary of the carpel , contains the megasporangium protected by two layers of integuments and the ovary wall . Within each megasporangium , a megasporocyte undergoes meiosis , generating four megaspores — three small and one large . Only the large megaspore survives ; it produces the female gametophyte , referred to as the embryo sac . The megaspore divides three times to form an eight-cell stage . <hl> Four of these cells migrate to each pole of the embryo sac ; two come to the equator , and will eventually fuse to form a 2 n polar nucleus ; the three cells away from the egg form antipodals , and the two cells closest to the egg become the synergids . <hl> <hl> The mature embryo sac contains one egg cell , two synergids or “ helper ” cells , three antipodal cells , and two polar nuclei in a central cell . <hl> When a pollen grain reaches the stigma , a pollen tube extends from the grain , grows down the style , and enters through the micropyle : an opening in the integuments of the ovule . The two sperm cells are deposited in the embryo sac .", "hl_sentences": "Four of these cells migrate to each pole of the embryo sac ; two come to the equator , and will eventually fuse to form a 2 n polar nucleus ; the three cells away from the egg form antipodals , and the two cells closest to the egg become the synergids . The mature embryo sac contains one egg cell , two synergids or “ helper ” cells , three antipodal cells , and two polar nuclei in a central cell .", "question": { "cloze_format": "In the course of double fertilization, one sperm cell fuses with the egg and the second one fuses with ________.", "normal_format": "In the course of double fertilization, one sperm cell fuses with the egg and the second one fuses with which of the following?", "question_choices": [ "the synergids", "the polar nuclei of the center cell", "the egg as well", "the antipodal cells" ], "question_id": "fs-idp1290560", "question_text": "In the course of double fertilization, one sperm cell fuses with the egg and the second one fuses with ________." }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 1, "ans_text": "a monocot" }, "bloom": null, "hl_context": "<hl> Plants in the monocot group are primarily identified as such by the presence of a single cotyledon in the seedling . <hl> <hl> Other anatomical features shared by monocots include veins that run parallel to the length of the leaves , and flower parts that are arranged in a three - or six-fold symmetry . <hl> <hl> True woody tissue is rarely found in monocots . <hl> <hl> In palm trees , vascular and parenchyma tissues produced by the primary and secondary thickening meristems form the trunk . <hl> <hl> The pollen from the first angiosperms was monosulcate , containing a single furrow or pore through the outer layer . <hl> This feature is still seen in the modern monocots . Vascular tissue of the stem is not arranged in any particular pattern . The root system is mostly adventitious and unusually positioned , with no major tap root . The monocots include familiar plants such as the true lilies ( which are at the origin of their alternate name of Liliopsida ) , orchids , grasses , and palms . Many important crops are monocots , such as rice and other cereals , corn , sugar cane , and tropical fruits like bananas and pineapples ( Figure 26.17 ) .", "hl_sentences": "Plants in the monocot group are primarily identified as such by the presence of a single cotyledon in the seedling . Other anatomical features shared by monocots include veins that run parallel to the length of the leaves , and flower parts that are arranged in a three - or six-fold symmetry . True woody tissue is rarely found in monocots . In palm trees , vascular and parenchyma tissues produced by the primary and secondary thickening meristems form the trunk . The pollen from the first angiosperms was monosulcate , containing a single furrow or pore through the outer layer .", "question": { "cloze_format": "Corn develops from a seedling with a single cotyledon, displays parallel veins on its leaves, and produces monosulcate pollen. It is most likely ___ .", "normal_format": "Corn develops from a seedling with a single cotyledon, displays parallel veins on its leaves, and produces monosulcate pollen. What is it most likely?", "question_choices": [ "a gymnosperm", "a monocot", "a eudicot", "a basal angiosperm" ], "question_id": "fs-idp29778752", "question_text": "Corn develops from a seedling with a single cotyledon, displays parallel veins on its leaves, and produces monosulcate pollen. It is most likely:" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 2, "ans_text": "nectar" }, "bloom": "3", "hl_context": "Coevolution of flowering plants and insects is a hypothesis that has received much attention and support , especially because both angiosperms and insects diversified at about the same time in the middle Mesozoic . Many authors have attributed the diversity of plants and insects to pollination and herbivory , or consumption of plants by insects and other animals . This is believed to have been as much a driving force as pollination . Coevolution of herbivores and plant defenses is observed in nature . Unlike animals , most plants cannot outrun predators or use mimicry to hide from hungry animals . A sort of arms race exists between plants and herbivores . <hl> To “ combat ” herbivores , some plant seeds — such as acorn and unripened persimmon — are high in alkaloids and therefore unsavory to some animals . <hl> <hl> Other plants are protected by bark , although some animals developed specialized mouth pieces to tear and chew vegetal material . <hl> <hl> Spines and thorns ( Figure 26.18 ) deter most animals , except for mammals with thick fur , and some birds have specialized beaks to get past such defenses . <hl>", "hl_sentences": "To “ combat ” herbivores , some plant seeds — such as acorn and unripened persimmon — are high in alkaloids and therefore unsavory to some animals . Other plants are protected by bark , although some animals developed specialized mouth pieces to tear and chew vegetal material . Spines and thorns ( Figure 26.18 ) deter most animals , except for mammals with thick fur , and some birds have specialized beaks to get past such defenses .", "question": { "cloze_format": "The plant structure that is not a defense against herbivory is ___.", "normal_format": "Which of the following plant structures is not a defense against herbivory?", "question_choices": [ "thorns", "spines", "nectar", "alkaloids" ], "question_id": "fs-idm10555264", "question_text": "Which of the following plant structures is not a defense against herbivory?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 0, "ans_text": "bees and butterflies" }, "bloom": "3", "hl_context": "Explore this website for additional information on pollinators . More than 80 percent of angiosperms depend on animals for pollination : the transfer of pollen from the anther to the stigma . Consequently , plants have developed many adaptations to attract pollinators . The specificity of specialized plant structures that target animals can be very surprising . It is possible , for example , to determine the type of pollinator favored by a plant just from the flower ’ s characteristics . <hl> Many bird or insect-pollinated flowers secrete nectar , which is a sugary liquid . <hl> <hl> They also produce both fertile pollen , for reproduction , and sterile pollen rich in nutrients for birds and insects . <hl> <hl> Butterflies and bees can detect ultraviolet light . <hl> <hl> Flowers that attract these pollinators usually display a pattern of low ultraviolet reflectance that helps them quickly locate the flower's center and collect nectar while being dusted with pollen ( Figure 26.19 ) . <hl> Large , red flowers with little smell and a long funnel shape are preferred by hummingbirds , who have good color perception , a poor sense of smell , and need a strong perch . <hl> White flowers opened at night attract moths . <hl> <hl> Other animals — such as bats , lemurs , and lizards — can also act as pollinating agents . <hl> Any disruption to these interactions , such as the disappearance of bees as a consequence of colony collapse disorders , can lead to disaster for agricultural industries that depend heavily on pollinated crops .", "hl_sentences": "Many bird or insect-pollinated flowers secrete nectar , which is a sugary liquid . They also produce both fertile pollen , for reproduction , and sterile pollen rich in nutrients for birds and insects . Butterflies and bees can detect ultraviolet light . Flowers that attract these pollinators usually display a pattern of low ultraviolet reflectance that helps them quickly locate the flower's center and collect nectar while being dusted with pollen ( Figure 26.19 ) . White flowers opened at night attract moths . Other animals — such as bats , lemurs , and lizards — can also act as pollinating agents .", "question": { "cloze_format": "White and sweet-smelling flowers with abundant nectar are probably pollinated by ___.", "normal_format": "What is likely the pollinator of white, sweet-smelling flowers with abundant nectar?", "question_choices": [ "bees and butterflies", "flies", "birds", "wind" ], "question_id": "fs-idm90052592", "question_text": "White and sweet-smelling flowers with abundant nectar are probably pollinated by" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 3, "ans_text": "wind" }, "bloom": "3", "hl_context": "<hl> Grasses are a successful group of flowering plants that are wind pollinated . <hl> <hl> They produce large amounts of powdery pollen carried over large distances by the wind . <hl> <hl> The flowers are small and wisp-like . <hl> Large trees such as oaks , maples , and birches are also wind pollinated .", "hl_sentences": "Grasses are a successful group of flowering plants that are wind pollinated . They produce large amounts of powdery pollen carried over large distances by the wind . The flowers are small and wisp-like .", "question": { "cloze_format": "Abundant and powdery pollen produced by small, indistinct flowers is probably transported by ___ .", "normal_format": "What is likely the transporter of abundant and powdery pollen produced by small, indistinct flowers?", "question_choices": [ "bees and butterflies", "flies", "birds", "wind" ], "question_id": "fs-idm39473840", "question_text": "Abundant and powdery pollen produced by small, indistinct flowers is probably transported by:" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 3, "ans_text": "all of the above" }, "bloom": null, "hl_context": "The relatively new field of ethnobotany studies the interaction between a particular culture and the plants native to the region . Seed plants have a large influence on day-to-day human life . <hl> Not only are plants the major source of food and medicine , they also influence many other aspects of society , from clothing to industry . <hl> The medicinal properties of plants were recognized early on in human cultures . From the mid - 1900s , synthetic chemicals began to supplant plant-based remedies . <hl> Seed plants have many other uses , including providing wood as a source of timber for construction , fuel , and material to build furniture . <hl> Most paper is derived from the pulp of coniferous trees . Fibers of seed plants such as cotton , flax , and hemp are woven into cloth . Textile dyes , such as indigo , were mostly of plant origin until the advent of synthetic chemical dyes .", "hl_sentences": "Not only are plants the major source of food and medicine , they also influence many other aspects of society , from clothing to industry . Seed plants have many other uses , including providing wood as a source of timber for construction , fuel , and material to build furniture .", "question": { "cloze_format": "Plants are a source of ________.", "normal_format": "What are plants a source of?", "question_choices": [ "food", "fuel", "medicine", "all of the above" ], "question_id": "fs-idm37266304", "question_text": "Plants are a source of ________." }, "references_are_paraphrase": null } ]
26
26.1 Evolution of Seed Plants Learning Objectives By the end of this section, you will be able to: Explain when seed plants first appeared and when gymnosperms became the dominant plant group Describe the two major innovations that allowed seed plants to reproduce in the absence of water Discuss the purpose of pollen grains and seeds Describe the significance of angiosperms bearing both flowers and fruit The first plants to colonize land were most likely closely related to modern day mosses (bryophytes) and are thought to have appeared about 500 million years ago. They were followed by liverworts (also bryophytes) and primitive vascular plants—the pterophytes—from which modern ferns are derived. The lifecycle of bryophytes and pterophytes is characterized by the alternation of generations, like gymnosperms and angiosperms; what sets bryophytes and pterophytes apart from gymnosperms and angiosperms is their reproductive requirement for water. The completion of the bryophyte and pterophyte life cycle requires water because the male gametophyte releases sperm, which must swim—propelled by their flagella—to reach and fertilize the female gamete or egg. After fertilization, the zygote matures and grows into a sporophyte, which in turn will form sporangia or "spore vessels." In the sporangia, mother cells undergo meiosis and produce the haploid spores. Release of spores in a suitable environment will lead to germination and a new generation of gametophytes. In seed plants, the evolutionary trend led to a dominant sporophyte generation, and at the same time, a systematic reduction in the size of the gametophyte: from a conspicuous structure to a microscopic cluster of cells enclosed in the tissues of the sporophyte. Whereas lower vascular plants, such as club mosses and ferns, are mostly homosporous (produce only one type of spore), all seed plants, or spermatophytes , are heterosporous. They form two types of spores: megaspores (female) and microspores (male). Megaspores develop into female gametophytes that produce eggs, and microspores mature into male gametophytes that generate sperm. Because the gametophytes mature within the spores, they are not free-living, as are the gametophytes of other seedless vascular plants. Heterosporous seedless plants are seen as the evolutionary forerunners of seed plants. Seeds and pollen—two critical adaptations to drought, and to reproduction that doesn’t require water—distinguish seed plants from other (seedless) vascular plants. Both adaptations were required for the colonization of land begun by the bryophytes and their ancestors. Fossils place the earliest distinct seed plants at about 350 million years ago. The first reliable record of gymnosperms dates their appearance to the Pennsylvanian period, about 319 million years ago ( Figure 26.2 ). Gymnosperms were preceded by progymnosperms , the first naked seed plants, which arose about 380 million years ago. Progymnosperms were a transitional group of plants that superficially resembled conifers (cone bearers) because they produced wood from the secondary growth of the vascular tissues; however, they still reproduced like ferns, releasing spores into the environment. Gymnosperms dominated the landscape in the early (Triassic) and middle (Jurassic) Mesozoic era. Angiosperms surpassed gymnosperms by the middle of the Cretaceous (about 100 million years ago) in the late Mesozoic era, and today are the most abundant plant group in most terrestrial biomes. Pollen and seed were innovative structures that allowed seed plants to break their dependence on water for reproduction and development of the embryo, and to conquer dry land. The pollen grains are the male gametophytes, which contain the sperm (gametes) of the plant. The small haploid (1 n ) cells are encased in a protective coat that prevents desiccation (drying out) and mechanical damage. Pollen grains can travel far from their original sporophyte, spreading the plant’s genes. The seed offers the embryo protection, nourishment, and a mechanism to maintain dormancy for tens or even thousands of years, ensuring germination can occur when growth conditions are optimal. Seeds therefore allow plants to disperse the next generation through both space and time. With such evolutionary advantages, seed plants have become the most successful and familiar group of plants, in part because of their size and striking appearance. Evolution of Gymnosperms The fossil plant Elkinsia polymorpha , a "seed fern" from the Devonian period—about 400 million years ago—is considered the earliest seed plant known to date. Seed ferns ( Figure 26.3 ) produced their seeds along their branches without specialized structures. What makes them the first true seed plants is that they developed structures called cupules to enclose and protect the ovule —the female gametophyte and associated tissues—which develops into a seed upon fertilization. Seed plants resembling modern tree ferns became more numerous and diverse in the coal swamps of the Carboniferous period. Fossil records indicate the first gymnosperms (progymnosperms) most likely originated in the Paleozoic era, during the middle Devonian period: about 390 million years ago. Following the wet Mississippian and Pennsylvanian periods, which were dominated by giant fern trees, the Permian period was dry. This gave a reproductive edge to seed plants, which are better adapted to survive dry spells. The Ginkgoales, a group of gymnosperms with only one surviving species—the Gingko biloba— were the first gymnosperms to appear during the lower Jurassic. Gymnosperms expanded in the Mesozoic era (about 240 million years ago), supplanting ferns in the landscape, and reaching their greatest diversity during this time. The Jurassic period was as much the age of the cycads (palm-tree-like gymnosperms) as the age of the dinosaurs. Gingkoales and the more familiar conifers also dotted the landscape. Although angiosperms (flowering plants) are the major form of plant life in most biomes, gymnosperms still dominate some ecosystems, such as the taiga (boreal forests) and the alpine forests at higher mountain elevations ( Figure 26.4 ) because of their adaptation to cold and dry growth conditions. Seeds and Pollen as an Evolutionary Adaptation to Dry Land Unlike bryophyte and fern spores (which are haploid cells dependent on moisture for rapid development of gametophytes), seeds contain a diploid embryo that will germinate into a sporophyte. Storage tissue to sustain growth and a protective coat give seeds their superior evolutionary advantage. Several layers of hardened tissue prevent desiccation, and free reproduction from the need for a constant supply of water. Furthermore, seeds remain in a state of dormancy—induced by desiccation and the hormone abscisic acid—until conditions for growth become favorable. Whether blown by the wind, floating on water, or carried away by animals, seeds are scattered in an expanding geographic range, thus avoiding competition with the parent plant. Pollen grains ( Figure 26.5 ) are male gametophytes and are carried by wind, water, or a pollinator. The whole structure is protected from desiccation and can reach the female organs without dependence on water. Male gametes reach female gametophyte and the egg cell gamete though a pollen tube: an extension of a cell within the pollen grain. The sperm of modern gymnosperms lack flagella, but in cycads and the Gingko , the sperm still possess flagella that allow them to swim down the pollen tube to the female gamete; however, they are enclosed in a pollen grain. Evolution of Angiosperms Undisputed fossil records place the massive appearance and diversification of angiosperms in the middle to late Mesozoic era. Angiosperms (“seed in a vessel”) produce a flower containing male and/or female reproductive structures. Fossil evidence ( Figure 26.6 ) indicates that flowering plants first appeared in the Lower Cretaceous, about 125 million years ago, and were rapidly diversifying by the Middle Cretaceous, about 100 million years ago. Earlier traces of angiosperms are scarce. Fossilized pollen recovered from Jurassic geological material has been attributed to angiosperms. A few early Cretaceous rocks show clear imprints of leaves resembling angiosperm leaves. By the mid-Cretaceous, a staggering number of diverse flowering plants crowd the fossil record. The same geological period is also marked by the appearance of many modern groups of insects, including pollinating insects that played a key role in ecology and the evolution of flowering plants. Although several hypotheses have been offered to explain this sudden profusion and variety of flowering plants, none have garnered the consensus of paleobotanists (scientists who study ancient plants). New data in comparative genomics and paleobotany have, however, shed some light on the evolution of angiosperms. Rather than being derived from gymnosperms, angiosperms form a sister clade (a species and its descendents) that developed in parallel with the gymnosperms. The two innovative structures of flowers and fruit represent an improved reproductive strategy that served to protect the embryo, while increasing genetic variability and range. Paleobotanists debate whether angiosperms evolved from small woody bushes, or were basal angiosperms related to tropical grasses. Both views draw support from cladistics studies, and the so-called woody magnoliid hypothesis—which proposes that the early ancestors of angiosperms were shrubs—also offers molecular biological evidence. The most primitive living angiosperm is considered to be Amborella trichopoda , a small plant native to the rainforest of New Caledonia, an island in the South Pacific. Analysis of the genome of A. trichopoda has shown that it is related to all existing flowering plants and belongs to the oldest confirmed branch of the angiosperm family tree. A few other angiosperm groups called basal angiosperms, are viewed as primitive because they branched off early from the phylogenetic tree. Most modern angiosperms are classified as either monocots or eudicots, based on the structure of their leaves and embryos. Basal angiosperms, such as water lilies, are considered more primitive because they share morphological traits with both monocots and eudicots. Flowers and Fruits as an Evolutionary Adaptation Angiosperms produce their gametes in separate organs, which are usually housed in a flower . Both fertilization and embryo development take place inside an anatomical structure that provides a stable system of sexual reproduction largely sheltered from environmental fluctuations. Flowering plants are the most diverse phylum on Earth after insects; flowers come in a bewildering array of sizes, shapes, colors, smells, and arrangements. Most flowers have a mutualistic pollinator, with the distinctive features of flowers reflecting the nature of the pollination agent. The relationship between pollinator and flower characteristics is one of the great examples of coevolution. Following fertilization of the egg, the ovule grows into a seed. The surrounding tissues of the ovary thicken, developing into a fruit that will protect the seed and often ensure its dispersal over a wide geographic range. Not all fruits develop from an ovary; such structures are “false fruits.” Like flowers, fruit can vary tremendously in appearance, size, smell, and taste. Tomatoes, walnut shells and avocados are all examples of fruit. As with pollen and seeds, fruits also act as agents of dispersal. Some may be carried away by the wind. Many attract animals that will eat the fruit and pass the seeds through their digestive systems, then deposit the seeds in another location. Cockleburs are covered with stiff, hooked spines that can hook into fur (or clothing) and hitch a ride on an animal for long distances. The cockleburs that clung to the velvet trousers of an enterprising Swiss hiker, George de Mestral, inspired his invention of the loop and hook fastener he named Velcro. Evolution Connection Building Phylogenetic Trees with Analysis of DNA Sequence Alignments All living organisms display patterns of relationships derived from their evolutionary history. Phylogeny is the science that describes the relative connections between organisms, in terms of ancestral and descendant species. Phylogenetic trees, such as the plant evolutionary history shown in Figure 26.7 , are tree-like branching diagrams that depict these relationships. Species are found at the tips of the branches. Each branching point, called a node, is the point at which a single taxonomic group (taxon), such as a species, separates into two or more species. Phylogenetic trees have been built to describe the relationships between species since Darwin’s time. Traditional methods involve comparison of homologous anatomical structures and embryonic development, assuming that closely related organisms share anatomical features during embryo development. Some traits that disappear in the adult are present in the embryo; for example, a human fetus, at one point, has a tail. The study of fossil records shows the intermediate stages that link an ancestral form to its descendants. Most of these approaches are imprecise and lend themselves to multiple interpretations. As the tools of molecular biology and computational analysis have been developed and perfected in recent years, a new generation of tree-building methods has taken shape. The key assumption is that genes for essential proteins or RNA structures, such as the ribosomal RNA, are inherently conserved because mutations (changes in the DNA sequence) could compromise the survival of the organism. DNA from minute amounts of living organisms or fossils can be amplified by polymerase chain reaction (PCR) and sequenced, targeting the regions of the genome that are most likely to be conserved between species. The genes encoding the ribosomal RNA from the small 18S subunit and plastid genes are frequently chosen for DNA alignment analysis. Once the sequences of interest are obtained, they are compared with existing sequences in databases such as GenBank, which is maintained by The National Center for Biotechnology Information. A number of computational tools are available to align and analyze sequences. Sophisticated computer analysis programs determine the percentage of sequence identity or homology. Sequence homology can be used to estimate the evolutionary distance between two DNA sequences and reflect the time elapsed since the genes separated from a common ancestor. Molecular analysis has revolutionized phylogenetic trees. In some cases, prior results from morphological studies have been confirmed: for example, confirming Amborella trichopoda as the most primitive angiosperm known. However, some groups and relationships have been rearranged as a result of DNA analysis. 26.2 Gymnosperms Learning Objectives By the end of this section, you will be able to: Discuss the type of seeds produced by gymnosperms, as well as other characteristics of gymnosperms State which period saw the first appearance of gymnosperms and explain when they were the dominant plant life List the four groups of modern-day gymnosperms and provide examples of each Gymnosperms , meaning “naked seeds,” are a diverse group of seed plants and are paraphyletic. Paraphyletic groups are those in which not all members are descendants of a single common ancestor. Their characteristics include naked seeds, separate female and male gametes, pollination by wind, and tracheids (which transport water and solutes in the vascular system). Gymnosperm seeds are not enclosed in an ovary; rather, they are exposed on cones or modified leaves. Sporophylls are specialized leaves that produce sporangia. The term strobilus (plural = strobili) describes a tight arrangement of sporophylls around a central stalk, as seen in cones. Some seeds are enveloped by sporophyte tissues upon maturation. The layer of sporophyte tissue that surrounds the megasporangium, and later, the embryo, is called the integument . Gymnosperms were the dominant phylum in Mesozoic era. They are adapted to live where fresh water is scarce during part of the year, or in the nitrogen-poor soil of a bog. Therefore, they are still the prominent phylum in the coniferous biome or taiga, where the evergreen conifers have a selective advantage in cold and dry weather. Evergreen conifers continue low levels of photosynthesis during the cold months, and are ready to take advantage of the first sunny days of spring. One disadvantage is that conifers are more susceptible than deciduous trees to infestations because conifers do not lose their leaves all at once. They cannot, therefore, shed parasites and restart with a fresh supply of leaves in spring. The life cycle of a gymnosperm involves alternation of generations, with a dominant sporophyte in which the female gametophyte resides, and reduced gametophytes. All gymnosperms are heterosporous. The male and female reproductive organs can form in cones or strobili. Male and female sporangia are produced either on the same plant, described as monoecious (“one home” or bisexual), or on separate plants, referred to as dioecious (“two homes” or unisexual) plants. The life cycle of a conifer will serve as our example of reproduction in gymnosperms. Life Cycle of a Conifer Pine trees are conifers (cone bearing) and carry both male and female sporophylls on the same mature sporophyte. Therefore, they are monoecious plants. Like all gymnosperms, pines are heterosporous and generate two different types of spores: male microspores and female megaspores. In the male cones, or staminate cones, the microsporocytes give rise to pollen grains by meiosis. In the spring, large amounts of yellow pollen are released and carried by the wind. Some gametophytes will land on a female cone. Pollination is defined as the initiation of pollen tube growth. The pollen tube develops slowly, and the generative cell in the pollen grain divides into two haploid sperm cells by mitosis. At fertilization, one of the sperm cells will finally unite its haploid nucleus with the haploid nucleus of a haploid egg cell. Female cones, or ovulate cones , contain two ovules per scale. One megaspore mother cell, or megasporocyte , undergoes meiosis in each ovule. Three of the four cells break down; only a single surviving cell will develop into a female multicellular gametophyte, which encloses archegonia (an archegonium is a reproductive organ that contains a single large egg). Upon fertilization, the diploid egg will give rise to the embryo, which is enclosed in a seed coat of tissue from the parent plant. Fertilization and seed development is a long process in pine trees: it may take up to two years after pollination. The seed that is formed contains three generations of tissues: the seed coat that originates from the sporophyte tissue, the gametophyte that will provide nutrients, and the embryo itself. Figure 26.8 illustrates the life cycle of a conifer. The sporophyte (2 n ) phase is the longest phase in the life of a gymnosperm. The gametophytes (1 n )—microspores and megaspores—are reduced in size. It may take more than year between pollination and fertilization while the pollen tube grows towards the megasporocyte (2 n ), which undergoes meiosis into megaspores. The megaspores will mature into eggs (1 n ). Visual Connection At what stage does the diploid zygote form? when the female cone begins to bud from the tree at fertilization when the seeds drop from the tree when the pollen tube begins to grow Link to Learning Watch this video to see the process of seed production in gymnosperms. Click to view content Diversity of Gymnosperms Modern gymnosperms are classified into four phyla. Coniferophyta, Cycadophyta, and Ginkgophyta are similar in their production of secondary cambium (cells that generate the vascular system of the trunk or stem and are partially specialized for water transportation) and their pattern of seed development. However, the three phyla are not closely related phylogenetically to each other. Gnetophyta are considered the closest group to angiosperms because they produce true xylem tissue. Conifers (Coniferophyta) Conifers are the dominant phylum of gymnosperms, with the most variety of species ( Figure 26.9 ). Most are typically tall trees that usually bear scale-like or needle-like leaves. Water evaporation from leaves is reduced by their thin shape and the thick cuticle. Snow slides easily off needle-shaped leaves, keeping the load light and decreasing breaking of branches. Adaptations to cold and dry weather explain the predominance of conifers at high altitudes and in cold climates. Conifers include familiar evergreen trees such as pines, spruces, firs, cedars, sequoias, and yews. A few species are deciduous and lose their leaves in fall. The European larch and the tamarack are examples of deciduous conifers ( Figure 26.9 c ). Many coniferous trees are harvested for paper pulp and timber. The wood of conifers is more primitive than the wood of angiosperms; it contains tracheids, but no vessel elements, and is therefore referred to as “soft wood.” Cycads Cycads thrive in mild climates, and are often mistaken for palms because of the shape of their large, compound leaves. Cycads bear large cones ( Figure 26.10 ), and may be pollinated by beetles rather than wind: unusual for a gymnosperm. They dominated the landscape during the age of dinosaurs in the Mesozoic, but only a hundred or so species persisted to modern times. They face possible extinction, and several species are protected through international conventions. Because of their attractive shape, they are often used as ornamental plants in gardens in the tropics and subtropics. Gingkophytes The single surviving species of the gingkophytes group is the Gingko biloba ( Figure 26.11 ). Its fan-shaped leaves—unique among seed plants because they feature a dichotomous venation pattern—turn yellow in autumn and fall from the tree. For centuries, G. biloba was cultivated by Chinese Buddhist monks in monasteries, which ensured its preservation. It is planted in public spaces because it is unusually resistant to pollution. Male and female organs are produced on separate plants. Typically, gardeners plant only male trees because the seeds produced by the female plant have an off-putting smell of rancid butter. Gnetophytes Gnetophytes are the closest relative to modern angiosperms, and include three dissimilar genera of plants: Ephedra , Gnetum , and Welwitschia ( Figure 26.12 ). Like angiosperms, they have broad leaves. In tropical and subtropical zones, gnetophytes are vines or small shrubs. Ephedra occurs in dry areas of the West Coast of the United States and Mexico. Ephedra ’s small, scale-like leaves are the source of the compound ephedrine, which is used in medicine as a potent decongestant. Because ephedrine is similar to amphetamines, both in chemical structure and neurological effects, its use is restricted to prescription drugs. Like angiosperms, but unlike other gymnosperms, all gnetophytes possess vessel elements in their xylem. Link to Learning Watch this BBC video describing the amazing strangeness of Welwitschia. Click to view content 26.3 Angiosperms Learning Objectives By the end of this section, you will be able to: Explain why angiosperms are the dominant form of plant life in most terrestrial ecosystems Describe the main parts of a flower and their purpose Detail the life cycle of an angiosperm Discuss the two main groups of flowering plants From their humble and still obscure beginning during the early Jurassic period, the angiosperms—or flowering plants—have evolved to dominate most terrestrial ecosystems ( Figure 26.13 ). With more than 250,000 species, the angiosperm phylum (Anthophyta) is second only to insects in terms of diversification. The success of angiosperms is due to two novel reproductive structures: flowers and fruit. The function of the flower is to ensure pollination. Flowers also provide protection for the ovule and developing embryo inside a receptacle. The function of the fruit is seed dispersal. They also protect the developing seed. Different fruit structures or tissues on fruit—such as sweet flesh, wings, parachutes, or spines that grab—reflect the dispersal strategies that help spread seeds. Flowers Flowers are modified leaves, or sporophylls, organized around a central stalk. Although they vary greatly in appearance, all flowers contain the same structures: sepals, petals, carpels, and stamens. The peduncle attaches the flower to the plant. A whorl of sepals (collectively called the calyx ) is located at the base of the peduncle and encloses the unopened floral bud. Sepals are usually photosynthetic organs, although there are some exceptions. For example, the corolla in lilies and tulips consists of three sepals and three petals that look virtually identical. Petals , collectively the corolla , are located inside the whorl of sepals and often display vivid colors to attract pollinators. Flowers pollinated by wind are usually small, feathery, and visually inconspicuous. Sepals and petals together form the perianth . The sexual organs (carpels and stamens) are located at the center of the flower. As illustrated in Figure 26.14 , styles, stigmas, and ovules constitute the female organ: the gynoecium or carpel . Flower structure is very diverse, and carpels may be singular, multiple, or fused. Multiple fused carpels comprise a pistil . The megaspores and the female gametophytes are produced and protected by the thick tissues of the carpel. A long, thin structure called a style leads from the sticky stigma , where pollen is deposited, to the ovary , enclosed in the carpel. The ovary houses one or more ovules, each of which will develop into a seed upon fertilization. The male reproductive organs, the stamens (collectively called the androecium), surround the central carpel. Stamens are composed of a thin stalk called a filament and a sac-like structure called the anther. The filament supports the anther , where the microspores are produced by meiosis and develop into pollen grains. Fruit As the seed develops, the walls of the ovary thicken and form the fruit. The seed forms in an ovary, which also enlarges as the seeds grow. In botany, a fertilized and fully grown, ripened ovary is a fruit. Many foods commonly called vegetables are actually fruit. Eggplants, zucchini, string beans, and bell peppers are all technically fruit because they contain seeds and are derived from the thick ovary tissue. Acorns are nuts, and winged maple whirligigs (whose botanical name is samara) are also fruit. Botanists classify fruit into more than two dozen different categories, only a few of which are actually fleshy and sweet. Mature fruit can be fleshy or dry. Fleshy fruit include the familiar berries, peaches, apples, grapes, and tomatoes. Rice, wheat, and nuts are examples of dry fruit. Another distinction is that not all fruits are derived from the ovary. For instance, strawberries are derived from the receptacle and apples from the pericarp, or hypanthium. Some fruits are derived from separate ovaries in a single flower, such as the raspberry. Other fruits, such as the pineapple, form from clusters of flowers. Additionally, some fruits, like watermelon and orange, have rinds. Regardless of how they are formed, fruits are an agent of seed dispersal. The variety of shapes and characteristics reflect the mode of dispersal. Wind carries the light dry fruit of trees and dandelions. Water transports floating coconuts. Some fruits attract herbivores with color or perfume, or as food. Once eaten, tough, undigested seeds are dispersed through the herbivore’s feces. Other fruits have burs and hooks to cling to fur and hitch rides on animals. The Life Cycle of an Angiosperm The adult, or sporophyte, phase is the main phase of an angiosperm’s life cycle ( Figure 26.15 ). Like gymnosperms, angiosperms are heterosporous. Therefore, they generate microspores, which will generate pollen grains as the male gametophytes, and megaspores, which will form an ovule that contains female gametophytes. Inside the anthers’ microsporangia, male gametophytes divide by meiosis to generate haploid microspores, which, in turn, undergo mitosis and give rise to pollen grains. Each pollen grain contains two cells: one generative cell that will divide into two sperm and a second cell that will become the pollen tube cell. Visual Connection If a flower lacked a megasporangium, what type of gamete would not form? If the flower lacked a microsporangium, what type of gamete would not form? The ovule, sheltered within the ovary of the carpel, contains the megasporangium protected by two layers of integuments and the ovary wall. Within each megasporangium, a megasporocyte undergoes meiosis, generating four megaspores—three small and one large. Only the large megaspore survives; it produces the female gametophyte, referred to as the embryo sac. The megaspore divides three times to form an eight-cell stage. Four of these cells migrate to each pole of the embryo sac; two come to the equator, and will eventually fuse to form a 2 n polar nucleus; the three cells away from the egg form antipodals, and the two cells closest to the egg become the synergids. The mature embryo sac contains one egg cell, two synergids or “helper” cells, three antipodal cells, and two polar nuclei in a central cell. When a pollen grain reaches the stigma, a pollen tube extends from the grain, grows down the style, and enters through the micropyle: an opening in the integuments of the ovule. The two sperm cells are deposited in the embryo sac. A double fertilization event then occurs. One sperm and the egg combine, forming a diploid zygote—the future embryo. The other sperm fuses with the 2 n polar nuclei, forming a triploid cell that will develop into the endosperm, which is tissue that serves as a food reserve. The zygote develops into an embryo with a radicle, or small root, and one (monocot) or two (dicot) leaf-like organs called cotyledons . This difference in the number of embryonic leaves is the basis for the two major groups of angiosperms: the monocots and the eudicots. Seed food reserves are stored outside the embryo, in the form of complex carbohydrates, lipids or proteins. The cotyledons serve as conduits to transmit the broken-down food reserves from their storage site inside the seed to the developing embryo. The seed consists of a toughened layer of integuments forming the coat, the endosperm with food reserves, and at the center, the well-protected embryo. Most flowers are monoecious or bisexual, which means that they carry both stamens and carpels; only a few species self-pollinate. Monoecious flowers are also known as “perfect” flowers because they contain both types of sex organs ( Figure 26.14 ). Both anatomical and environmental barriers promote cross-pollination mediated by a physical agent (wind or water), or an animal, such as an insect or bird. Cross-pollination increases genetic diversity in a species. Diversity of Angiosperms Angiosperms are classified in a single phylum: the Anthophyta . Modern angiosperms appear to be a monophyletic group, which means that they originate from a single ancestor. Flowering plants are divided into two major groups, according to the structure of the cotyledons, pollen grains, and other structures. Monocots include grasses and lilies, and eudicots or dicots form a polyphyletic group. Basal angiosperms are a group of plants that are believed to have branched off before the separation into monocots and eudicots because they exhibit traits from both groups. They are categorized separately in many classification schemes. The Magnoliidae (magnolia trees, laurels, and water lilies) and the Piperaceae (peppers) belong to the basal angiosperm group. Basal Angiosperms The Magnoliidae are represented by the magnolias: tall trees bearing large, fragrant flowers that have many parts and are considered archaic ( Figure 26.16 d ). Laurel trees produce fragrant leaves and small, inconspicuous flowers. The Laurales grow mostly in warmer climates and are small trees and shrubs. Familiar plants in this group include the bay laurel, cinnamon, spice bush ( Figure 26.16 a ), and avocado tree. The Nymphaeales are comprised of the water lilies, lotus ( Figure 26.16 c ), and similar plants; all species thrive in freshwater biomes, and have leaves that float on the water surface or grow underwater. Water lilies are particularly prized by gardeners, and have graced ponds and pools for thousands of years. The Piperales are a group of herbs, shrubs, and small trees that grow in the tropical climates. They have small flowers without petals that are tightly arranged in long spikes. Many species are the source of prized fragrance or spices, for example the berries of Piper nigrum ( Figure 26.16 b ) are the familiar black peppercorns that are used to flavor many dishes. Monocots Plants in the monocot group are primarily identified as such by the presence of a single cotyledon in the seedling. Other anatomical features shared by monocots include veins that run parallel to the length of the leaves, and flower parts that are arranged in a three- or six-fold symmetry. True woody tissue is rarely found in monocots. In palm trees, vascular and parenchyma tissues produced by the primary and secondary thickening meristems form the trunk. The pollen from the first angiosperms was monosulcate, containing a single furrow or pore through the outer layer. This feature is still seen in the modern monocots. Vascular tissue of the stem is not arranged in any particular pattern. The root system is mostly adventitious and unusually positioned, with no major tap root. The monocots include familiar plants such as the true lilies (which are at the origin of their alternate name of Liliopsida), orchids, grasses, and palms. Many important crops are monocots, such as rice and other cereals, corn, sugar cane, and tropical fruits like bananas and pineapples ( Figure 26.17 ). Eudicots Eudicots, or true dicots, are characterized by the presence of two cotyledons in the developing shoot. Veins form a network in leaves, and flower parts come in four, five, or many whorls. Vascular tissue forms a ring in the stem; in monocots, vascular tissue is scattered in the stem. Eudicots can be herbaceous (like grasses), or produce woody tissues. Most eudicots produce pollen that is trisulcate or triporate, with three furrows or pores. The root system is usually anchored by one main root developed from the embryonic radicle. Eudicots comprise two-thirds of all flowering plants. The major differences between monocots and eudicots are summarized in Table 26.1 . Many species exhibit characteristics that belong to either group; as such, the classification of a plant as a monocot or a eudicot is not always clearly evident. Comparison of Structural Characteristics of Monocots and Eudicots Characteristic Monocot Eudicot Cotyledon One Two Veins in Leaves Parallel Network (branched) Stem Vascular Tissue Scattered Arranged in ring pattern Roots Network of adventitious roots Tap root with many lateral roots Pollen Monosulcate Trisulcate Flower Parts Three or multiple of three Four, five, multiple of four or five and whorls Table 26.1 26.4 The Role of Seed Plants Learning Objectives By the end of this section, you will be able to: Explain how angiosperm diversity is due, in part, to multiple interactions with animals Describe ways in which pollination occurs Discuss the roles that plants play in ecosystems and how deforestation threatens plant biodiversity Without seed plants, life as we know it would not be possible. Plants play a key role in the maintenance of terrestrial ecosystems through stabilization of soils, cycling of carbon, and climate moderation. Large tropical forests release oxygen and act as carbon dioxide sinks. Seed plants provide shelter to many life forms, as well as food for herbivores, thereby indirectly feeding carnivores. Plant secondary metabolites are used for medicinal purposes and industrial production. Animals and Plants: Herbivory Coevolution of flowering plants and insects is a hypothesis that has received much attention and support, especially because both angiosperms and insects diversified at about the same time in the middle Mesozoic. Many authors have attributed the diversity of plants and insects to pollination and herbivory , or consumption of plants by insects and other animals. This is believed to have been as much a driving force as pollination. Coevolution of herbivores and plant defenses is observed in nature. Unlike animals, most plants cannot outrun predators or use mimicry to hide from hungry animals. A sort of arms race exists between plants and herbivores. To “combat” herbivores, some plant seeds—such as acorn and unripened persimmon—are high in alkaloids and therefore unsavory to some animals. Other plants are protected by bark, although some animals developed specialized mouth pieces to tear and chew vegetal material. Spines and thorns ( Figure 26.18 ) deter most animals, except for mammals with thick fur, and some birds have specialized beaks to get past such defenses. Herbivory has been used by seed plants for their own benefit in a display of mutualistic relationships. The dispersal of fruit by animals is the most striking example. The plant offers to the herbivore a nutritious source of food in return for spreading the plant’s genetic material to a wider area. An extreme example of collaboration between an animal and a plant is the case of acacia trees and ants. The trees support the insects with shelter and food. In return, ants discourage herbivores, both invertebrates and vertebrates, by stinging and attacking leaf-eating insects. Animals and Plants: Pollination Grasses are a successful group of flowering plants that are wind pollinated. They produce large amounts of powdery pollen carried over large distances by the wind. The flowers are small and wisp-like. Large trees such as oaks, maples, and birches are also wind pollinated. Link to Learning Explore this website for additional information on pollinators. More than 80 percent of angiosperms depend on animals for pollination : the transfer of pollen from the anther to the stigma. Consequently, plants have developed many adaptations to attract pollinators. The specificity of specialized plant structures that target animals can be very surprising. It is possible, for example, to determine the type of pollinator favored by a plant just from the flower’s characteristics. Many bird or insect-pollinated flowers secrete nectar , which is a sugary liquid. They also produce both fertile pollen, for reproduction, and sterile pollen rich in nutrients for birds and insects. Butterflies and bees can detect ultraviolet light. Flowers that attract these pollinators usually display a pattern of low ultraviolet reflectance that helps them quickly locate the flower's center and collect nectar while being dusted with pollen ( Figure 26.19 ). Large, red flowers with little smell and a long funnel shape are preferred by hummingbirds, who have good color perception, a poor sense of smell, and need a strong perch. White flowers opened at night attract moths. Other animals—such as bats, lemurs, and lizards—can also act as pollinating agents. Any disruption to these interactions, such as the disappearance of bees as a consequence of colony collapse disorders, can lead to disaster for agricultural industries that depend heavily on pollinated crops. Scientific Method Connection Testing Attraction of Flies by Rotting Flesh Smell Question: Will flowers that offer cues to bees attract carrion flies if sprayed with compounds that smell like rotten flesh? Background: Visitation of flowers by pollinating flies is a function mostly of smell. Flies are attracted by rotting flesh and carrions. The putrid odor seems to be the major attractant. The polyamines putrescine and cadaverine, which are the products of protein breakdown after animal death, are the source of the pungent smell of decaying meat. Some plants strategically attract flies by synthesizing polyamines similar to those generated by decaying flesh and thereby attract carrion flies. Flies seek out dead animals because they normally lay their eggs on them and their maggots feed on the decaying flesh. Interestingly, time of death can be determined by a forensic entomologist based on the stages and type of maggots recovered from cadavers. Hypothesis: Because flies are drawn to other organisms based on smell and not sight, a flower that is normally attractive to bees because of its colors will attract flies if it is sprayed with polyamines similar to those generated by decaying flesh. Test the hypothesis: Select flowers usually pollinated by bees. White petunia may be good choice. Divide the flowers into two groups, and while wearing eye protection and gloves, spray one group with a solution of either putrescine or cadaverine. (Putrescine dihydrochloride is typically available in 98 percent concentration; this can be diluted to approximately 50 percent for this experiment.) Place the flowers in a location where flies are present, keeping the sprayed and unsprayed flowers separated. Observe the movement of the flies for one hour. Record the number of visits to the flowers using a table similar to Table 26.2 . Given the rapid movement of flies, it may be beneficial to use a video camera to record the fly–flower interaction. Replay the video in slow motion to obtain an accurate record of the number of fly visits to the flowers. Repeat the experiment four more times with the same species of flower, but using different specimens. Repeat the entire experiment with a different type of flower that is normally pollinated by bees. Results of Number of Visits by Flies to Sprayed and Control/Unsprayed Flowers Trial # Sprayed Flowers Unsprayed Flowers 1 2 3 4 5 Table 26.2 Analyze your data: Review the data you have recorded. Average the number of visits that flies made to sprayed flowers over the course of the five trials (on the first flower type) and compare and contrast them to the average number of visits that flies made to the unsprayed/control flowers. Can you draw any conclusions regarding the attraction of the flies to the sprayed flowers? For the second flower type used, average the number of visits that flies made to sprayed flowers over the course of the five trials and compare and contrast them to the average number of visits that flies made to the unsprayed/control flowers. Can you draw any conclusions regarding the attraction of the flies to the sprayed flowers? Compare and contrast the average number of visits that flies made to the two flower types. Can you draw any conclusions about whether the appearance of the flower had any impact on the attraction of flies? Did smell override any appearance differences, or were the flies attracted to one flower type more than another? Form a conclusion: Do the results support the hypothesis? If not, how can this be explained? The Importance of Seed Plants in Human Life Seed plants are the foundation of human diets across the world ( Figure 26.20 ). Many societies eat almost exclusively vegetarian fare and depend solely on seed plants for their nutritional needs. A few crops (rice, wheat, and potatoes) dominate the agricultural landscape. Many crops were developed during the agricultural revolution, when human societies made the transition from nomadic hunter–gatherers to horticulture and agriculture. Cereals, rich in carbohydrates, provide the staple of many human diets. Beans and nuts supply proteins. Fats are derived from crushed seeds, as is the case for peanut and rapeseed (canola) oils, or fruits such as olives. Animal husbandry also consumes large amounts of crops. Staple crops are not the only food derived from seed plants. Fruits and vegetables provide nutrients, vitamins, and fiber. Sugar, to sweeten dishes, is produced from the monocot sugarcane and the eudicot sugar beet. Drinks are made from infusions of tea leaves, chamomile flowers, crushed coffee beans, or powdered cocoa beans. Spices come from many different plant parts: saffron and cloves are stamens and buds, black pepper and vanilla are seeds, the bark of a bush in the Laurales family supplies cinnamon, and the herbs that flavor many dishes come from dried leaves and fruit, such as the pungent red chili pepper. The volatile oils of flowers and bark provide the scent of perfumes. Additionally, no discussion of seed plant contribution to human diet would be complete without the mention of alcohol. Fermentation of plant-derived sugars and starches is used to produce alcoholic beverages in all societies. In some cases, the beverages are derived from the fermentation of sugars from fruit, as with wines and, in other cases, from the fermentation of carbohydrates derived from seeds, as with beers. Seed plants have many other uses, including providing wood as a source of timber for construction, fuel, and material to build furniture. Most paper is derived from the pulp of coniferous trees. Fibers of seed plants such as cotton, flax, and hemp are woven into cloth. Textile dyes, such as indigo, were mostly of plant origin until the advent of synthetic chemical dyes. Lastly, it is more difficult to quantify the benefits of ornamental seed plants. These grace private and public spaces, adding beauty and serenity to human lives and inspiring painters and poets alike. The medicinal properties of plants have been known to human societies since ancient times. There are references to the use of plants’ curative properties in Egyptian, Babylonian, and Chinese writings from 5,000 years ago. Many modern synthetic therapeutic drugs are derived or synthesized de novo from plant secondary metabolites. It is important to note that the same plant extract can be a therapeutic remedy at low concentrations, become an addictive drug at higher doses, and can potentially kill at high concentrations. Table 26.3 presents a few drugs, their plants of origin, and their medicinal applications. Plant Origin of Medicinal Compounds and Medical Applications Plant Compound Application Deadly nightshade ( Atropa belladonna ) Atropine Dilate eye pupils for eye exams Foxglove ( Digitalis purpurea ) Digitalis Heart disease, stimulates heart beat Yam ( Dioscorea spp.) Steroids Steroid hormones: contraceptive pill and cortisone Ephedra ( Ephedra spp.) Ephedrine Decongestant and bronchiole dilator Pacific yew ( Taxus brevifolia ) Taxol Cancer chemotherapy; inhibits mitosis Opium poppy ( Papaver somniferum ) Opioids Analgesic (reduces pain without loss of consciousness) and narcotic (reduces pain with drowsiness and loss of consciousness) in higher doses Quinine tree ( Cinchona spp.) Quinine Antipyretic (lowers body temperature) and antimalarial Willow ( Salix spp.) Salicylic acid (aspirin) Analgesic and antipyretic Table 26.3 Career Connection Ethnobotanist The relatively new field of ethnobotany studies the interaction between a particular culture and the plants native to the region. Seed plants have a large influence on day-to-day human life. Not only are plants the major source of food and medicine, they also influence many other aspects of society, from clothing to industry. The medicinal properties of plants were recognized early on in human cultures. From the mid-1900s, synthetic chemicals began to supplant plant-based remedies. Pharmacognosy is the branch of pharmacology that focuses on medicines derived from natural sources. With massive globalization and industrialization, there is a concern that much human knowledge of plants and their medicinal purposes will disappear with the cultures that fostered them. This is where ethnobotanists come in. To learn about and understand the use of plants in a particular culture, an ethnobotanist must bring in knowledge of plant life and an understanding and appreciation of diverse cultures and traditions. The Amazon forest is home to an incredible diversity of vegetation and is considered an untapped resource of medicinal plants; yet, both the ecosystem and its indigenous cultures are threatened with extinction. To become an ethnobotanist, a person must acquire a broad knowledge of plant biology, ecology and sociology. Not only are the plant specimens studied and collected, but also the stories, recipes, and traditions that are linked to them. For ethnobotanists, plants are not viewed solely as biological organisms to be studied in a laboratory, but as an integral part of human culture. The convergence of molecular biology, anthropology, and ecology make the field of ethnobotany a truly multidisciplinary science. Biodiversity of Plants Biodiversity ensures a resource for new food crops and medicines. Plant life balances ecosystems, protects watersheds, mitigates erosion, moderates climate and provides shelter for many animal species. Threats to plant diversity, however, come from many angles. The explosion of the human population, especially in tropical countries where birth rates are highest and economic development is in full swing, is leading to human encroachment into forested areas. To feed the larger population, humans need to obtain arable land, so there is massive clearing of trees. The need for more energy to power larger cities and economic growth therein leads to the construction of dams, the consequent flooding of ecosystems, and increased emissions of pollutants. Other threats to tropical forests come from poachers, who log trees for their precious wood. Ebony and Brazilian rosewood, both on the endangered list, are examples of tree species driven almost to extinction by indiscriminate logging. The number of plant species becoming extinct is increasing at an alarming rate. Because ecosystems are in a delicate balance, and seed plants maintain close symbiotic relationships with animals—whether predators or pollinators—the disappearance of a single plant can lead to the extinction of connected animal species. A real and pressing issue is that many plant species have not yet been catalogued, and so their place in the ecosystem is unknown. These unknown species are threatened by logging, habitat destruction, and loss of pollinators. They may become extinct before we have the chance to begin to understand the possible impacts from their disappearance. Efforts to preserve biodiversity take several lines of action, from preserving heirloom seeds to barcoding species. Heirloom seeds come from plants that were traditionally grown in human populations, as opposed to the seeds used for large-scale agricultural production. Barcoding is a technique in which one or more short gene sequences, taken from a well-characterized portion of the genome, are used to identify a species through DNA analysis.
introduction_to_intellectual_property
Chapter Outline 1.1 The Foundations of Patent Protection 1.2 The Weakness of Early Patent Systems 1.3 America’s Uniquely Democratic Patent System 1.4 The Role of the U.S. Legal System 1.5 What the U.S. Patent System Wrought 1.6 Patent-Eligible Inventions 1.7 Criteria for Patenting 1.8 Other Types of Patents 1.9 The Patenting Process Introduction
[ { "answer": { "ans_choice": 1, "ans_text": "B." }, "bloom": null, "hl_context": "<hl> utility patents , which preclude others from making , using , or selling the invention during the term of the patent , which begins on the grant date and ends 20 years from the filing date ( for an average of 17 to 18 years ) . <hl> But in", "hl_sentences": "utility patents , which preclude others from making , using , or selling the invention during the term of the patent , which begins on the grant date and ends 20 years from the filing date ( for an average of 17 to 18 years ) .", "question": { "cloze_format": "A patent gives an inventor the exclusive right to have ___ .", "normal_format": "A patent gives an inventor the exclusive right to which of the following?", "question_choices": [ "The ability to profit from their invention.", "The ability to prevent others from making, using, offering for sale, or selling the invention.", "The ability to prevent others from learning the secrets of the invention.", "All of the above." ], "question_id": "eip-297", "question_text": "A patent gives an inventor the exclusive right to which of the following?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 0, "ans_text": "A." }, "bloom": null, "hl_context": "<hl> The “ bargain ” theory starts with the commonsense premise that people will be encouraged to invent new products and services that benefit society if they are likely to profit by doing so . <hl> <hl> The U . S . Constitution thus offers inventors a bargain : If you invent something useful — e . g . , a cotton gin in 1794 that boosted agricultural production a hundredfold , or a semiconductor 163 years later that sparked the creation of a trillion-dollar new industry and millions of jobs — then the Constitution and statutes say that , as a quid pro quo , you can have the exclusive right to that invention for a “ limited time , ” after which it goes into the public domain and belongs to society . <hl>", "hl_sentences": "The “ bargain ” theory starts with the commonsense premise that people will be encouraged to invent new products and services that benefit society if they are likely to profit by doing so . The U . S . Constitution thus offers inventors a bargain : If you invent something useful — e . g . , a cotton gin in 1794 that boosted agricultural production a hundredfold , or a semiconductor 163 years later that sparked the creation of a trillion-dollar new industry and millions of jobs — then the Constitution and statutes say that , as a quid pro quo , you can have the exclusive right to that invention for a “ limited time , ” after which it goes into the public domain and belongs to society .", "question": { "cloze_format": "The “bargain” theory, a theoretical justification for patents, argues that ___ .", "normal_format": "The “bargain” theory, a theoretical justification for patents, argues which of the following?", "question_choices": [ "In exchange for inventing something useful, society gives the inventor the exclusive right to their invention for a limited time.", "The product of mental labor should be the property of its creator.", "Government negotiates with inventors to determine the value of an invention.", "None of the above." ], "question_id": "eip-664", "question_text": "The “bargain” theory, a theoretical justification for patents, argues which of the following?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 3, "ans_text": "D." }, "bloom": null, "hl_context": "As with any economic and legal instrument , patents have the potential to slow innovation if their grant of exclusive rights is too broad . <hl> But the overwhelming preponderance of economic research and real-world experience demonstrate that , on balance , intellectual property rights tend to stimulate invention , economic growth , and the diffusion of new technological knowledge in every country where they exist . <hl> <hl> In fact , new research in 2012 discovered that rather than blocking development , Thomas Edison ’ s seminal 1880 incandescent lamp patent ( No . <hl> <hl> 223,898 ) actually “ stimulated downstream development work ” that resulted in “ new technologies of commercial significance [ including ] the Tesla coil , hermetically sealed connectors , chemical vapor deposition process , tungsten lamp filaments and phosphorescent lighting that led to today ’ s fluorescent lamps . ” vii vii Ron D . Katznelson , “ Inventing Around Edison ’ s Incandescent Lamp Patent : Evidence of Patents ’ Role in Stimulating Downstream Development , ” May , 2012 , derived from : http://works.bepress.com/cgi/viewcontent.cgi?article=1073&context=rkatznelson <hl> <hl> From the earliest days of the United States , patent and legal records show how inventors ( including Thomas Edison ) regularly kept abreast of developments in their fields . <hl> <hl> They did this by studying patent descriptions published by both the USPTO as well as by industry publications such as Scientific American , which was founded in 1845 by Munn and Company , the leading patent agency of the nineteenth century , expressly to spread new technological knowledge and facilitate the buying and selling of patents . <hl> For example , Elias E . Reis — inventor of a number of devices to exploit the heat generated by electrical currents — reported that when he read in the Official Gazette in 1886 about a patent issued to Elihu Thomson for a new method of electric welding , “ there immediately opened up to my mind a field of new applications to which I saw I could apply my system of producing heat in large quantities . ” vi In many industries , specialized journals kept readers informed about new patents of interest . vi See “ Record of Elias E . Reis , ” 8 , Thomson v . Reis , case 13,971 , box 1,845 , Interference Case Files , 1836-1905 , Records of the Patent Office , Record Group 241 , National Archives , courtesy of B . Zorina Khan . <hl> It ’ s more than just “ likely . ” Extensive research in the United States and other nations shows that patents have served as a powerful stimulant to technological knowledge sharing . <hl> <hl> A 2006 survey published by the French economists Francois Leveque and Yann Meniere , for example , found that 88 percent of U . S . , European , and Japanese businesses rely upon the information disclosed in patents to keep up with technology advances and direct their own R & D efforts . <hl> v v Francois Leveque and Yann Meniere , “ Patents and Innovation : Friends or Foes ? ” CERNA ( Centre d ’ economie industrielle Ecole Nationale Superieure des Mines de Paris ) , December , 2006 .", "hl_sentences": "But the overwhelming preponderance of economic research and real-world experience demonstrate that , on balance , intellectual property rights tend to stimulate invention , economic growth , and the diffusion of new technological knowledge in every country where they exist . In fact , new research in 2012 discovered that rather than blocking development , Thomas Edison ’ s seminal 1880 incandescent lamp patent ( No . 223,898 ) actually “ stimulated downstream development work ” that resulted in “ new technologies of commercial significance [ including ] the Tesla coil , hermetically sealed connectors , chemical vapor deposition process , tungsten lamp filaments and phosphorescent lighting that led to today ’ s fluorescent lamps . ” vii vii Ron D . Katznelson , “ Inventing Around Edison ’ s Incandescent Lamp Patent : Evidence of Patents ’ Role in Stimulating Downstream Development , ” May , 2012 , derived from : http://works.bepress.com/cgi/viewcontent.cgi?article=1073&context=rkatznelson From the earliest days of the United States , patent and legal records show how inventors ( including Thomas Edison ) regularly kept abreast of developments in their fields . They did this by studying patent descriptions published by both the USPTO as well as by industry publications such as Scientific American , which was founded in 1845 by Munn and Company , the leading patent agency of the nineteenth century , expressly to spread new technological knowledge and facilitate the buying and selling of patents . It ’ s more than just “ likely . ” Extensive research in the United States and other nations shows that patents have served as a powerful stimulant to technological knowledge sharing . A 2006 survey published by the French economists Francois Leveque and Yann Meniere , for example , found that 88 percent of U . S . , European , and Japanese businesses rely upon the information disclosed in patents to keep up with technology advances and direct their own R & D efforts .", "question": { "cloze_format": "Patents also promote knowledge sharing through the following means: ___.", "normal_format": "Through which of the following means do patents also promote knowledge sharing?", "question_choices": [ "To get a patent, inventors must disclose the secrets of their inventions.", "Patents represent the world’s greatest library of technical knowledge.", "Innovators keep up with technical trends by reading other inventors’ patents.", "All of the above." ], "question_id": "eip-634", "question_text": "Through which of the following means do patents also promote knowledge sharing?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 2, "ans_text": "C." }, "bloom": null, "hl_context": "A growing public outcry ultimately forced Elizabeth ’ s successor James I to revoke these grants of trade monopolies in 1610 . <hl> In 1624 , the Statute of Monopolies formally repealed the practice and henceforth restricted patent rights <hl> <hl> patent monopolies were granted over the trade in such staples as salt , soap , starch , iron , and paper . <hl> <hl> Critics said these “ enriched the monopolist and robbed the community ” while doing absolutely nothing to stimulate new technology or industry . <hl>", "hl_sentences": "In 1624 , the Statute of Monopolies formally repealed the practice and henceforth restricted patent rights patent monopolies were granted over the trade in such staples as salt , soap , starch , iron , and paper . Critics said these “ enriched the monopolist and robbed the community ” while doing absolutely nothing to stimulate new technology or industry .", "question": { "cloze_format": "The Statute of Monopolies in 1624 ended the practice of granting patents for ___ .", "normal_format": "The Statute of Monopolies in 1624 ended the practice of granting patents for which of the following?", "question_choices": [ "Inventions that were not truly novel.", "The Crown’s favored inventors.", "Trade in staples such as salt or soap rather than for actual inventions.", "Inventions that helped industrialists monopolize whole industries." ], "question_id": "eip-781", "question_text": "The Statute of Monopolies in 1624 ended the practice of granting patents for which of the following?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 3, "ans_text": "D." }, "bloom": null, "hl_context": "<hl> What ’ s more , patent application fees were prohibitively high — more than 11 times the per capita annual income of the average British citizen — which put the system out of reach of all but the wealthy . <hl> Yet ironically , in the <hl> But the biggest problem with early patent systems was that they all shared a tendency to reinforce the wealth and prerogatives of elites , not the welfare and productive capacity of the whole of society . <hl> In Britain , patents were the creative work of others rather than invent for themselves . <hl> And there was generally no systematic examination of patents by technical experts , in part because this was viewed as an intrusion upon the prerogatives of the Crown . <hl> <hl> for ten years so long as they disclosed the details of their inventions . <hl> Most Venetian patents were granted in the field of glass making , and when a large number of these glass makers emigrated to other countries in Europe , they sought similar", "hl_sentences": "What ’ s more , patent application fees were prohibitively high — more than 11 times the per capita annual income of the average British citizen — which put the system out of reach of all but the wealthy . But the biggest problem with early patent systems was that they all shared a tendency to reinforce the wealth and prerogatives of elites , not the welfare and productive capacity of the whole of society . And there was generally no systematic examination of patents by technical experts , in part because this was viewed as an intrusion upon the prerogatives of the Crown . for ten years so long as they disclosed the details of their inventions .", "question": { "cloze_format": "The practice that was common in early patent systems was ___ .", "normal_format": "Which of the following practices were common in early patent systems?", "question_choices": [ "Exorbitantly high patent fees.", "Limited or no disclosure of the details of the invention.", "No examination for patent validity.", "All of the above." ], "question_id": "eip-858", "question_text": "Which of the following practices were common in early patent systems?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 3, "ans_text": "D." }, "bloom": null, "hl_context": "<hl> British patent law also severely limited the ability of inventors to sell or license the rights to their discoveries , as noted in a contemporary 1832 book entitled <hl> <hl> But the biggest problem with early patent systems was that they all shared a tendency to reinforce the wealth and prerogatives of elites , not the welfare and productive capacity of the whole of society . <hl> In Britain , patents were <hl> patent monopolies were granted over the trade in such staples as salt , soap , starch , iron , and paper . <hl> <hl> Critics said these “ enriched the monopolist and robbed the community ” while doing absolutely nothing to stimulate new technology or industry . <hl>", "hl_sentences": "British patent law also severely limited the ability of inventors to sell or license the rights to their discoveries , as noted in a contemporary 1832 book entitled But the biggest problem with early patent systems was that they all shared a tendency to reinforce the wealth and prerogatives of elites , not the welfare and productive capacity of the whole of society . patent monopolies were granted over the trade in such staples as salt , soap , starch , iron , and paper . Critics said these “ enriched the monopolist and robbed the community ” while doing absolutely nothing to stimulate new technology or industry .", "question": { "cloze_format": "Early patent systems tended to have the effect of ___ on the overall economy.", "normal_format": "Early patent systems tended to have which of the following effects on the overall economy?", "question_choices": [ "Innovation was limited to a small sector of the population.", "Biased toward incumbent industries, early patent systems did not encourage disruptive change.", "Early patent systems reinforced the wealth of elites, not the productive capacity of society.", "All of the above." ], "question_id": "eip-49", "question_text": "Early patent systems tended to have which of the following effects on the overall economy?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 1, "ans_text": "B." }, "bloom": null, "hl_context": "<hl> It was , therefore , a critical task of the leaders of the new American nation to design institutions — including a patent system — that would encourage economic activity and investments to spur the growth of America ’ s primitive economy . <hl>", "hl_sentences": "It was , therefore , a critical task of the leaders of the new American nation to design institutions — including a patent system — that would encourage economic activity and investments to spur the growth of America ’ s primitive economy .", "question": { "cloze_format": "The Founding Fathers created the U.S. patent system with the overarching goal ___ in mind.", "normal_format": "The Founding Fathers created the U.S. patent system with which overarching goal in mind?", "question_choices": [ "To defend America’s newly won independence.", "To rapidly stimulate the growth of domestic industry.", "To create advanced new weapons for America’s young army.", "None of the above." ], "question_id": "eip-193", "question_text": "The Founding Fathers created the U.S. patent system with which overarching goal in mind?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 3, "ans_text": "D." }, "bloom": null, "hl_context": "<hl> forerunners of what we today call the middle class — who were possessed with what publisher Hezekiah Niles called “ a universal ambition to go forward . ” <hl> <hl> Most important , unlike the tenant farmers and laborers who made up the bulk of England ’ s rigid class society , the vast majority of Americans were free-holding small farmers , merchants , shopkeepers , artisans , and mechanics — the <hl> <hl> It was , therefore , a critical task of the leaders of the new American nation to design institutions — including a patent system — that would encourage economic activity and investments to spur the growth of America ’ s primitive economy . <hl>", "hl_sentences": "forerunners of what we today call the middle class — who were possessed with what publisher Hezekiah Niles called “ a universal ambition to go forward . ” Most important , unlike the tenant farmers and laborers who made up the bulk of England ’ s rigid class society , the vast majority of Americans were free-holding small farmers , merchants , shopkeepers , artisans , and mechanics — the It was , therefore , a critical task of the leaders of the new American nation to design institutions — including a patent system — that would encourage economic activity and investments to spur the growth of America ’ s primitive economy .", "question": { "cloze_format": "The U.S. patent system was designed to tap the creative and productive potential of ___ .", "normal_format": "The U.S. patent system was designed to tap the creative and productive potential of which of the following?", "question_choices": [ "Their abundant natural resources.", "Their large stock of imported goods and machinery.", "Rich agricultural lands.", "An enterprising population with a “universal ambition to go forward”" ], "question_id": "eip-492", "question_text": "The U.S. patent system was designed to tap the creative and productive potential of which of the following?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 2, "ans_text": "C." }, "bloom": null, "hl_context": "<hl> “ working requirements , ” and encouragement of robust trade in patent rights — all had a powerfully beneficial impact on the nation ’ s economic growth . <hl> <hl> In sum , these six unique features of the U . S . patent system — low fees , simplified procedures , examination of applications by trained experts , systematic disclosure of new technological knowledge , lack of <hl> <hl> No “ Working Requirements ” Reduced Monopoly Control The fifth distinguishing feature of the U . S . patent system was the lack of any sort of “ working requirements . ” In the debate over HR - 41 , the bill that became the first U . S . patent law in 1790 , “ the Senate suggested requiring patentees to make products based on the patent or license others to do so . <hl> <hl> But the House rejected this as an infringement of patentees ’ rights . ” xviii <hl>", "hl_sentences": "“ working requirements , ” and encouragement of robust trade in patent rights — all had a powerfully beneficial impact on the nation ’ s economic growth . In sum , these six unique features of the U . S . patent system — low fees , simplified procedures , examination of applications by trained experts , systematic disclosure of new technological knowledge , lack of No “ Working Requirements ” Reduced Monopoly Control The fifth distinguishing feature of the U . S . patent system was the lack of any sort of “ working requirements . ” In the debate over HR - 41 , the bill that became the first U . S . patent law in 1790 , “ the Senate suggested requiring patentees to make products based on the patent or license others to do so . But the House rejected this as an infringement of patentees ’ rights . ” xviii", "question": { "cloze_format": "Of the following statements, the fact that ___ was NOT a unique feature of the U.S. patent system.", "normal_format": "Which of the following was NOT a unique feature of the U.S. patent system?", "question_choices": [ "It was affordable by the common person.", "It had an examination system to determine patent validity.", "Patentees were required to make or sell products based on their inventions.", "It had simplified application procedures.", "It required full disclosure of the details of the invention.", "It allowed for the sale and licensing of patent rights." ], "question_id": "eip-292", "question_text": "Which of the following was NOT a unique feature of the U.S. patent system?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 2, "ans_text": "C." }, "bloom": null, "hl_context": "invention . <hl> Novelty , utility , and non-obviousness — the holy trinity of patents . <hl> <hl> That patents could be used as tradable assets by non-practicing entities without the wealth to commercialize their own discoveries was a wholly unique feature of the American patent system . <hl> By 1880 , 85 percent of all U . S . patents <hl> No “ Working Requirements ” Reduced Monopoly Control The fifth distinguishing feature of the U . S . patent system was the lack of any sort of “ working requirements . ” In the debate over HR - 41 , the bill that became the first U . S . patent law in 1790 , “ the Senate suggested requiring patentees to make products based on the patent or license others to do so . <hl> <hl> But the House rejected this as an infringement of patentees ’ rights . ” xviii <hl>", "hl_sentences": "Novelty , utility , and non-obviousness — the holy trinity of patents . That patents could be used as tradable assets by non-practicing entities without the wealth to commercialize their own discoveries was a wholly unique feature of the American patent system . No “ Working Requirements ” Reduced Monopoly Control The fifth distinguishing feature of the U . S . patent system was the lack of any sort of “ working requirements . ” In the debate over HR - 41 , the bill that became the first U . S . patent law in 1790 , “ the Senate suggested requiring patentees to make products based on the patent or license others to do so . But the House rejected this as an infringement of patentees ’ rights . ” xviii", "question": { "cloze_format": "A statement that is NOT true about the U.S. patent system is that ___.", "normal_format": "Which of the following is NOT true of the U.S. patent system?", "question_choices": [ "Novelty, non-obviousness, and utility determine patent validity, not the identity or business model of the inventor.", "Patents are freely transferable and tradable property rights.", "You can’t infringe a patent if you honestly don’t know that it exists.", "Patent holders are not required to make or sell products based on their inventions." ], "question_id": "eip-482", "question_text": "Which of the following is NOT true of the U.S. patent system?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 2, "ans_text": "C." }, "bloom": null, "hl_context": "<hl> figures show the patent litigation rate during the decade 2001 to 2011 was less than half that — only 1.52 percent . <hl> From 2002 to 2012 , reflecting the increased suits but also the increased ( 276,788 ) patents issued , the litigation rate was 1.57 percent . <hl> litigation rate at that time — defined as the number of patent suits filed in a decade divided by the number of patents issued in that decade — reached 3.6 percent . <hl> xxxiv <hl> Even more surprising , given the common belief in a patent litigation “ explosion ” today , patent and legal records from the golden age of invention during the mid-nineteenth century U . S . Industrial Revolution show that the patent <hl>", "hl_sentences": "figures show the patent litigation rate during the decade 2001 to 2011 was less than half that — only 1.52 percent . litigation rate at that time — defined as the number of patent suits filed in a decade divided by the number of patents issued in that decade — reached 3.6 percent . Even more surprising , given the common belief in a patent litigation “ explosion ” today , patent and legal records from the golden age of invention during the mid-nineteenth century U . S . Industrial Revolution show that the patent", "question": { "cloze_format": "Compared with the Industrial Revolution, the overall patent litigation rate today is that ___.", "normal_format": "Compared with the Industrial Revolution, what is the overall patent litigation rate today?", "question_choices": [ "It is twice what it used to be.", "It is about the same as it used to be.", "It is less than half what it used to be." ], "question_id": "eip-773", "question_text": "Compared with the Industrial Revolution, what is the overall patent litigation rate today?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 1, "ans_text": "B." }, "bloom": null, "hl_context": "<hl> Although patent litigation is costly , the historical record suggests that it serves a vital function by settling the validity and disputed ownership of patent rights so these can be commercialized into new products , new services , <hl>", "hl_sentences": "Although patent litigation is costly , the historical record suggests that it serves a vital function by settling the validity and disputed ownership of patent rights so these can be commercialized into new products , new services ,", "question": { "cloze_format": "Historically speaking, patent litigation has served to ___ .", "normal_format": "Historically speaking, patent litigation has served to which of the following?", "question_choices": [ "Slow innovation and R&D.", "Settle disputed rights to new technology so commercialization can proceed.", "Block others from designing around patents." ], "question_id": "eip-704", "question_text": "Historically speaking, patent litigation has served to which of the following?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 0, "ans_text": "A." }, "bloom": null, "hl_context": "<hl> of inventions as Britain , although their populations were by then roughly equal in size . <hl> the unrivaled leader of the industrial revolution — in the number of new inventions patented , even though Britain still had more than twice America ’ s population . <hl> By 1870 , as noted earlier , the United States was patenting more than five times the number <hl> <hl> Only two months after America ’ s first patent law was signed in 1790 , in fact , Thomas Jefferson himself noted that it had “ given a spring to invention beyond my conception . ” Within 13 years , America surpassed Britain — until then , <hl>", "hl_sentences": "of inventions as Britain , although their populations were by then roughly equal in size . By 1870 , as noted earlier , the United States was patenting more than five times the number Only two months after America ’ s first patent law was signed in 1790 , in fact , Thomas Jefferson himself noted that it had “ given a spring to invention beyond my conception . ” Within 13 years , America surpassed Britain — until then ,", "question": { "cloze_format": "It took ___ after the first patent law was signed in 1790 for the United States to surpass Britain in the number of new inventions being patented.", "normal_format": "How many years after the first patent law was signed in 1790 did it take for the United States to surpass Britain in the number of new inventions being patented?", "question_choices": [ "13 years.", "75 years.", "40 years.", "100 years." ], "question_id": "eip-923", "question_text": "How many years after the first patent law was signed in 1790 did it take for the United States to surpass Britain in the number of new inventions being patented?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 1, "ans_text": "B." }, "bloom": null, "hl_context": "<hl> Clearly , whenever the United States has undergone a major industrial renaissance during which technology advances lead not only to the birth of new industries , but also to the reshaping of existing ones , patenting levels rise <hl>", "hl_sentences": "Clearly , whenever the United States has undergone a major industrial renaissance during which technology advances lead not only to the birth of new industries , but also to the reshaping of existing ones , patenting levels rise", "question": { "cloze_format": "Historically, in the United States, there have been major surges in new patent filings after ___.", "normal_format": "Historically, in the United States, there have been major surges in new patent filings after which of the following?", "question_choices": [ "A sharp increase in patent litigation.", "New technological advances leading to the birth of new industries.", "A Supreme Court decision on a major patent case.", "None of the above." ], "question_id": "eip-725", "question_text": "Historically, in the United States, there have been major surges in new patent filings after which of the following?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 2, "ans_text": "C." }, "bloom": null, "hl_context": "<hl> The patent system has also been crucial in facilitating the growth of new start-up businesses , with 67 percent of entrepreneurs reporting that they find patents valuable in obtaining venture financing . <hl> xli", "hl_sentences": "The patent system has also been crucial in facilitating the growth of new start-up businesses , with 67 percent of entrepreneurs reporting that they find patents valuable in obtaining venture financing .", "question": { "cloze_format": "The percentage of entrepreneurs that say that patents are vital to securing venture funding is ___ .", "normal_format": "What percentage of entrepreneurs say that patents are vital to securing venture funding?", "question_choices": [ "20 percent.", "40 percent.", "67 percent." ], "question_id": "eip-330", "question_text": "What percentage of entrepreneurs say that patents are vital to securing venture funding?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 3, "ans_text": "D." }, "bloom": null, "hl_context": "<hl> And for the first time in human history , a nation had come to see its greatness not in empire or military might or royal lineage , but in its capacity for technological progress . <hl>", "hl_sentences": "And for the first time in human history , a nation had come to see its greatness not in empire or military might or royal lineage , but in its capacity for technological progress .", "question": { "cloze_format": "The United States was the only nation to define its greatness in its capacity for ___.", "normal_format": "The United States was the only nation to define its greatness in its capacity for which of the following?", "question_choices": [ "Economic growth.", "Military superiority.", "Bringing freedom to oppressed elsewhere in the world.", "Technological progress." ], "question_id": "eip-502", "question_text": "The United States was the only nation to define its greatness in its capacity for which of the following?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 0, "ans_text": "A." }, "bloom": null, "hl_context": "Mathematical Formulas Not Patentable There are other discoveries that fall into the broad category of abstract ideas and are thus unpatentable . You cannot patent a mathematical formula . You cannot patent a law of nature , such as Einstein ’ s E = MC 2 . <hl> And you cannot patent natural phenomena like electricity ( discovered by William Gilbert in 1600 ) or the Higgs particle that gives all matter its mass ( discovered by researchers at the Large Hadron Collider on July 4 , 2012 ) . <hl> These all exist independently of human intervention , whether we have discovered them or formulated their rules yet or not , and must be freely available to all of humanity for its understanding and betterment . To restate the distinction , you cannot patent electromagnetism but you can patent a telegraph that uses electromagnetism to communicate rapidly over great distances , as Samuel Morse did in 1840 with patent no . 1647 . And although", "hl_sentences": "And you cannot patent natural phenomena like electricity ( discovered by William Gilbert in 1600 ) or the Higgs particle that gives all matter its mass ( discovered by researchers at the Large Hadron Collider on July 4 , 2012 ) .", "question": { "cloze_format": "___ is NOT patentable.", "normal_format": "Which of the following is NOT patentable?", "question_choices": [ "Electricity.", "A random number generator.", "A device that uses electricity to communicate." ], "question_id": "eip-27", "question_text": "Which of the following is NOT patentable?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 1, "ans_text": "B." }, "bloom": null, "hl_context": "<hl> produce a tangible transformative result . <hl> Paradox , ” and it has left many in-house patent groups struggling for a solution . <hl> One thing is clear : To be patentable nowadays , software has to take a genuinely-inventive step and either trigger an action , employ a device , or in some other way <hl>", "hl_sentences": "produce a tangible transformative result . One thing is clear : To be patentable nowadays , software has to take a genuinely-inventive step and either trigger an action , employ a device , or in some other way", "question": { "cloze_format": "Software might be patentable ___.", "normal_format": "When might a software be patentable?", "question_choices": [ "If it contains a new, non-obvious, and useful algorithm.", "If it takes a genuinely-inventive step to either trigger an action, employ a device, or in some other way produce a tangible transformative result.", "If it records the sale of T-shirts over the Internet.", "None of the above." ], "question_id": "eip-209", "question_text": "When might a software be patentable?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 1, "ans_text": "B." }, "bloom": null, "hl_context": "<hl> Diamond v . Diehr . <hl> <hl> Parker v . Flook . <hl> <hl> Gottschalk v . Benson <hl> <hl> trilogy ” — reveal the evolution of its thinking about software patentability . <hl> Mixed Verdicts on Software Patentability The federal courts and the U . S . Supreme Court have tried to clarify the limits of patentability in the computer age . <hl> Three Supreme Court cases in particular — often called the “ patent-eligibility <hl>", "hl_sentences": "Diamond v . Diehr . Parker v . Flook . Gottschalk v . Benson trilogy ” — reveal the evolution of its thinking about software patentability . Three Supreme Court cases in particular — often called the “ patent-eligibility", "question": { "cloze_format": "The case that was NOT one of the Supreme Court’s “software-eligibility trilogy” of cases was ___.", "normal_format": "Which of the following cases was NOT one of the Supreme Court’s “software-eligibility trilogy” of cases?", "question_choices": [ "Gottschalk v. Benson", "Williams & Wilkins v. United States", "Parker v. Flook", "Diamond v. Diehr" ], "question_id": "eip-581", "question_text": "Which of the following cases was NOT one of the Supreme Court’s “software-eligibility trilogy” of cases?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 3, "ans_text": "D." }, "bloom": null, "hl_context": "<hl> patentable invention . ” <hl> standard had invalidated 13 additional software patents . <hl> As technology policy journalist Timothy B . Lee noted , “ The courts are sending a pretty clear message : you can ’ t take a commonplace human activity , do it with a computer , and call that a <hl> <hl> patentable new invention . <hl> <hl> the Court ruled that taking some activity that people have been doing for centuries — in this case , holding funds in escrow until a transaction is completed — and then merely “ doing it through a computer ” did not turn this age-old activity into a <hl> <hl> Alice v . CLS Bank , <hl>", "hl_sentences": "patentable invention . ” As technology policy journalist Timothy B . Lee noted , “ The courts are sending a pretty clear message : you can ’ t take a commonplace human activity , do it with a computer , and call that a patentable new invention . the Court ruled that taking some activity that people have been doing for centuries — in this case , holding funds in escrow until a transaction is completed — and then merely “ doing it through a computer ” did not turn this age-old activity into a Alice v . CLS Bank ,", "question": { "cloze_format": "The court case that most severely limited software patentability is the one of ___.", "normal_format": "Which court case most severely limited software patentability?", "question_choices": [ "State Street Bank v. Signature Financial Group", "In re Bilski", "Mayo Collaborative Services v. Prometheus Laboratories", "Alice v. CLS Bank" ], "question_id": "eip-621", "question_text": "Which court case most severely limited software patentability?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 0, "ans_text": "A." }, "bloom": null, "hl_context": "<hl> Paradox , ” and it has left many in-house patent groups struggling for a solution . <hl> One thing is clear : To be patentable nowadays , software has to take a genuinely-inventive step and either trigger an action , employ a device , or in some other way <hl> Cronin calls this the “ Alice <hl> <hl> to patent nowadays as a result of the Supreme Court ’ s <hl> computing , Big Data , machine learning , connectivity , mobility and location-based services , and on-demand and anything-as-a-service software applications and business processes . <hl> But ironically , these high-value innovations are also the most difficult <hl>", "hl_sentences": "Paradox , ” and it has left many in-house patent groups struggling for a solution . Cronin calls this the “ Alice to patent nowadays as a result of the Supreme Court ’ s But ironically , these high-value innovations are also the most difficult", "question": { "cloze_format": "The so-called “Alice paradox” means ___.", "normal_format": "What is the so-called “Alice paradox”?", "question_choices": [ "The highest-value new software products and services are also hardest to patent.", "You can get software patents, but you can’t enforce them.", "You can only patent software that replicates human activity.", "None of the above." ], "question_id": "eip-112", "question_text": "What is the so-called “Alice paradox”?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 1, "ans_text": "B." }, "bloom": null, "hl_context": "<hl> On June 13 , 2013 , however , the U . S . Supreme Court finally determined in a unanimous decision that a naturally occurring DNA segment is a product of nature and cannot be patented merely because it has been isolated , thereby <hl> decision . <hl> On August 16 , 2012 , however , the U . S . Court of Appeals for the Federal Circuit once again reaffirmed Myriad ’ s right to patent the isolated genes BCRA 1 and BCRA 2 , which are involved in most inherited forms of breast and ovarian cancer . <hl>", "hl_sentences": "On June 13 , 2013 , however , the U . S . Supreme Court finally determined in a unanimous decision that a naturally occurring DNA segment is a product of nature and cannot be patented merely because it has been isolated , thereby On August 16 , 2012 , however , the U . S . Court of Appeals for the Federal Circuit once again reaffirmed Myriad ’ s right to patent the isolated genes BCRA 1 and BCRA 2 , which are involved in most inherited forms of breast and ovarian cancer .", "question": { "cloze_format": "The Supreme Court case that held that a naturally occurring DNA segment CANNOT be patented is called the ___ .", "normal_format": "Which of the following Supreme Court cases held that a naturally occurring DNA segment CANNOT be patented?", "question_choices": [ "Mayo Collaborative Services v. Prometheus Labs., Inc.", "Association for Molecular Pathology v. Myriad Genetics, Inc.", "Nautilus, Inc. v. Biosig Instruments, Inc." ], "question_id": "eip-386", "question_text": "Which of the following Supreme Court cases held that a naturally occurring DNA segment CANNOT be patented?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 1, "ans_text": "B." }, "bloom": null, "hl_context": "invention . <hl> Novelty , utility , and non-obviousness — the holy trinity of patents . <hl>", "hl_sentences": "Novelty , utility , and non-obviousness — the holy trinity of patents .", "question": { "cloze_format": "___ is NOT a requirement for patent eligibility.", "normal_format": "Which of the following is NOT a requirement for patent eligibility?", "question_choices": [ "Novel.", "Revolutionary.", "Non-obvious.", "Useful." ], "question_id": "eip-582", "question_text": "Which of the following is NOT a requirement for patent eligibility?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 1, "ans_text": "B." }, "bloom": null, "hl_context": "If any of the above is true of an invention , it is said to have been “ anticipated ” and cannot be patented . <hl> These novelty requirements exist whether the “ prior art ” — the catchall term for any previous patent , publication , or use — is domestic or foreign . <hl>", "hl_sentences": "These novelty requirements exist whether the “ prior art ” — the catchall term for any previous patent , publication , or use — is domestic or foreign .", "question": { "cloze_format": "The term “prior art” refers to ___.", "normal_format": "What does the term “prior art” refer to?", "question_choices": [ "Any previous private discussions of an invention or its components.", "Any previous patent, publication, or public use of an invention.", "Any previous speculation about an invention.", "None of the above." ], "question_id": "eip-700", "question_text": "What does the term “prior art” refer to?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 0, "ans_text": "A." }, "bloom": null, "hl_context": "<hl> Even when no fraud is intended , the utility of a product or process must be demonstrate in a patent application — not presumed , but affirmatively demonstrated . <hl> <hl> Simply put , the thing or the method you have invented must actually work <hl>", "hl_sentences": "Even when no fraud is intended , the utility of a product or process must be demonstrate in a patent application — not presumed , but affirmatively demonstrated . Simply put , the thing or the method you have invented must actually work", "question": { "cloze_format": "To meet the requirement for utility, an invention must ___ .", "normal_format": "To meet the requirement for utility, which of the following must an invention do?", "question_choices": [ "Work or function as intended.", "Be of some benefit to society.", "Be a worthwhile product, process, or composition of matter.", "All of the above." ], "question_id": "eip-208", "question_text": "To meet the requirement for utility, which of the following must an invention do?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 2, "ans_text": "C." }, "bloom": null, "hl_context": "<hl> more than the sum of its parts and met a large and previously-unfilled need in the marketplace . <hl> The millions of people who take selfies everyday is certainly proof of that . <hl> But things are not so obvious when it comes to inventing a camera phone . <hl> <hl> Even though it ’ s composed of well-known and widely-available components , combining the two did satisfy the requirement for non-obviousness because it became <hl> <hl> decide , “ Hey , why not put those wheels on a chair ? ” you won ’ t get a patent for it . <hl> <hl> That ’ s because combining two such widely-known and available elements would be obvious to anyone skilled in the art of office furniture design . <hl> <hl> But to offer a more practical example , say you invent a wheeled cart to move office supplies more easily between departments . <hl> <hl> If this is the first such wheeled office cart in history , you can get a patent for it . <hl> But if you then", "hl_sentences": "more than the sum of its parts and met a large and previously-unfilled need in the marketplace . But things are not so obvious when it comes to inventing a camera phone . Even though it ’ s composed of well-known and widely-available components , combining the two did satisfy the requirement for non-obviousness because it became decide , “ Hey , why not put those wheels on a chair ? ” you won ’ t get a patent for it . That ’ s because combining two such widely-known and available elements would be obvious to anyone skilled in the art of office furniture design . But to offer a more practical example , say you invent a wheeled cart to move office supplies more easily between departments . If this is the first such wheeled office cart in history , you can get a patent for it .", "question": { "cloze_format": "The reason combining a camera with a cell phone in a smartphone would pass the test for non-obviousness, whereas putting wheels from a chair onto an office cart would not is that ___ .", "normal_format": "Why would combining a camera with a cell phone in a smartphone pass the test for non-obviousness, whereas putting wheels from a chair onto an office cart would not?", "question_choices": [ "The technology in a smartphone is much more complicated.", "Putting wheels from a chair onto a cart is less difficult.", "Combining a camera and a cell phone produced an unexpected result." ], "question_id": "eip-975", "question_text": "Why would combining a camera with a cell phone in a smartphone pass the test for non-obviousness, whereas putting wheels from a chair onto an office cart would not?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 2, "ans_text": "C." }, "bloom": null, "hl_context": "<hl> Understand why non-obviousness is the most difficult hurdle to overcome . <hl>", "hl_sentences": "Understand why non-obviousness is the most difficult hurdle to overcome .", "question": { "cloze_format": "Of the three criteria for patenting, the most difficult to surmount is ___.", "normal_format": "Of the three criteria for patenting, which is the most difficult to surmount?", "question_choices": [ "Utility.", "Novelty.", "Non-obviousness." ], "question_id": "eip-720", "question_text": "Of the three criteria for patenting, which is the most difficult to surmount?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 2, "ans_text": "C." }, "bloom": null, "hl_context": "<hl> plant — i . e . , those grown not with seeds but by grafting , budding , or cutting . <hl> <hl> A plant need not be useful to qualify for a patent , but it must be distinctive in its color , habit , soil , flavor , productivity , form , or other aspects . <hl> distinctiveness , and non-obviousness . <hl> To be patentable , plants must be cultivated rather than found in the wild , and plant patents are granted only to protect a new , distinct , and non-obvious variety of asexually reproduced <hl>", "hl_sentences": "plant — i . e . , those grown not with seeds but by grafting , budding , or cutting . A plant need not be useful to qualify for a patent , but it must be distinctive in its color , habit , soil , flavor , productivity , form , or other aspects . To be patentable , plants must be cultivated rather than found in the wild , and plant patents are granted only to protect a new , distinct , and non-obvious variety of asexually reproduced", "question": { "cloze_format": "Plant patents are granted for ___ .", "normal_format": "For which of the following are plant patents granted?", "question_choices": [ "Bioengineered plants.", "Naturally grown plants that are distinctively different.", "Plants that are asexually cultivated, not grown from seeds.", "All of the above." ], "question_id": "eip-394", "question_text": "For which of the following are plant patents granted?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 1, "ans_text": "B." }, "bloom": null, "hl_context": "<hl> distinctiveness , and non-obviousness . <hl> To be patentable , plants must be cultivated rather than found in the wild , and plant patents are granted only to protect a new , distinct , and non-obvious variety of asexually reproduced <hl> Instead of novelty , utility , and non-obviousness , the criteria for plant patentability are novelty , <hl>", "hl_sentences": "distinctiveness , and non-obviousness . Instead of novelty , utility , and non-obviousness , the criteria for plant patentability are novelty ,", "question": { "cloze_format": "The three patentability criteria for plant patents are ___ .", "normal_format": "What are the three patentability criteria for plant patents?", "question_choices": [ "Novelty, utility, and non-obviousness.", "Novelty, distinctiveness, and non-obviousness.", "Novelty, beauty, and non-obviousness." ], "question_id": "eip-464", "question_text": "What are the three patentability criteria for plant patents?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 1, "ans_text": "B." }, "bloom": null, "hl_context": "<hl> Design Patents Design patents are granted to protect new , original , and non-obvious ornamental designs for articles of manufacture . <hl> Examples include Apple ’ s 2009 and 2010 patents — No . D593087", "hl_sentences": "Design Patents Design patents are granted to protect new , original , and non-obvious ornamental designs for articles of manufacture .", "question": { "cloze_format": "Design patents are granted for ___ .", "normal_format": "What are design patents granted for?", "question_choices": [ "Functional designs for manufactured items, like the shape of a chair.", "Ornamental designs for items of manufacture, like the fabric design of a chair.", "All of the above." ], "question_id": "eip-686", "question_text": "What are design patents granted for?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 2, "ans_text": "C." }, "bloom": null, "hl_context": "<hl> ornamentality , and non-obviousness . <hl> Like plant patents , design patents also substitute a different test than utility in their requirements for patentability . <hl> Instead of the novelty , utility , and non-obvious requirements for utility patents , the criteria for design patents are novelty , <hl>", "hl_sentences": "ornamentality , and non-obviousness . Instead of the novelty , utility , and non-obvious requirements for utility patents , the criteria for design patents are novelty ,", "question": { "cloze_format": "___ are the three patentability criteria for a design patent.", "normal_format": "What are the three patentability criteria for a design patent?", "question_choices": [ "Novelty, utility, and non-obviousness.", "Novelty, beauty, and non-obviousness.", "Novelty, ornamentality, and non-obviousness." ], "question_id": "eip-232", "question_text": "What are the three patentability criteria for a design patent?" }, "references_are_paraphrase": null } ]
1
1.1 The Foundations of Patent Protection Learning Objectives After completing this section, you will be able to Describe the philosophical logic behind granting patents. Describe the role of patents in fostering invention. Do Patents Really Promote Innovation? Before reading this section, please watch this overview video covering the usefulness of patents - how ironic that a system for granting exclusive rights to inventors is the greatest vehicle for knowledge-sharing and technology transfer ever devised by human beings. What Is a Patent? A patent is an intellectual property right granted by the government of a nation to an inventor that gives them the exclusive right to the invention for up to 20 years, in exchange for disclosing the details of the new technology to society for its ultimate benefit. In the United States, a patent is a legal instrument in the form of a document issued by the United States Patent and Trademark Office (USPTO). It gives the inventor of any new, useful, and non-obvious machine, process, manufacture, or composition of matter the right “to exclude others from making, using, offering for sale, or selling the invention throughout the United States or importing the invention into the United States” for a limited time in exchange for public disclosure of the invention. i A U.S. patent is only recognized domestically, and cannot be enforced in another country. i United States Patent and Trademark Office. (2012, January 26). Patents. Retrieved from www.uspto.gov/patents/index.jsp History of Patents in the United States The legal foundation for U.S. intellectual property rights was laid by the Founders in 1787, in the very first Article of the U.S. Constitution, which outlined the precepts of our democratic society. In Article 1, Section 8, Clause 8 of the Constitution, Congress was given the authority to “promote the progress of Science and useful Arts, by securing for limited times to authors and inventors the exclusive right to their respective writings and discoveries”. ii ii U.S. Constitution Arr. 1, § 8 America was the first country in the world to enshrine intellectual property rights in its national constitution. And the Founders did this quite deliberately, says B. Zorina Khan, an economic historian at Bowdoin College whose book, The Democratization of Invention: Patents and Copyrights in American Economic Development , was awarded the Alice Hanson Jones Prize for an outstanding work in economic history. iii “To the men who gathered in Philadelphia to ‘promote the general welfare,’” Khan wrote, “it was self-evident that ideas, industrial and cultural inventions, and democratic values were integrally related. American democratic institutions would ensure that rewards accrued to the deserving based on [merit] rather than on the arbitrary basis of class, patronage, or privilege.” iii B. Zorina Khan, The Democratization of Invention: Patents and Copyrights in American Economic Development , 1790-1920, Cambridge University Press, 2005. Indeed, the Founders viewed intellectual property rights as vital to the new nation’s economic survival. As George Washington himself stated in his first annual address to Congress in 1790, “The advancement of agriculture, commerce, and manufactures by all proper means will not, I trust, need recommendation. But I cannot forbear intimating to you the expediency of giving effectual encouragement to the introduction of new and useful inventions.” The question is, with all the challenges they faced, why did the Founders think it so crucial to create a strong intellectual property system? Their reasons were both universal—i.e., applying to all societies—and also very particular to America’s revolutionary experience. “Bargain” Theory vs. “Natural Rights” Theory Every society that affirms intellectual property rights offers two justifications for doing so: the bargain or contract theory and the natural rights theory . “Bargain” Theory The “bargain” theory starts with the commonsense premise that people will be encouraged to invent new products and services that benefit society if they are likely to profit by doing so. The U.S. Constitution thus offers inventors a bargain: If you invent something useful—e.g., a cotton gin in 1794 that boosted agricultural production a hundredfold, or a semiconductor 163 years later that sparked the creation of a trillion-dollar new industry and millions of jobs—then the Constitution and statutes say that, as a quid pro quo, you can have the exclusive right to that invention for a “limited time,” after which it goes into the public domain and belongs to society. There is something so simple yet economically potent about this concept. As Abraham Lincoln—America’s only presidential patentee ( No. 6469 for a device to lift boats over shoals)—noted, the beauty of the patent system is that it “added the fuel of interest to the fire of genius.” “Natural Rights” Theory The “natural rights” theory, meanwhile, invokes another commonsense premise that most of us instinctively hold to be true: that the product of mental labor is by all rights the property of its creator, no less than the product of physical labor is the property of its creator (or of the person who purchases it from that creator). This is what Daniel Webster was referring to when he said, “The American Constitution does not attempt to give an inventor a right to their invention, or an author a right to his composition; it recognizes an original, pre-existing, inherent right of property in such invention or composition.” This right is not absolute, of course, and inventors’ inherent rights may at times be circumscribed by national security or other concerns. But in exchange for disclosing to the public the nature and details of the invention, the Constitution authorizes the government to enforce the inventor’s exclusive property right to that invention for a limited time. Two important public policy goals are thus served. The inherent property rights of inventors and authors to their creations are protected, thereby helping to ensure that the wellsprings of creation and productivity do not dry up for lack of incentive. And yet the benefits derived from these inventions and creations are ultimately harnessed to the public good through disclosure, thus promoting the progress of the nation and “the general welfare” of its citizens. How Patents Foster Innovation To help understand why patent rights not only encourage inventors but also promote the wider diffusion of new technology for the benefit of society, economic historians Naomi Lamoreaux and the late Kenneth Sokoloff suggested the following thought experiment: Imagine a world in which there was no patent system to guarantee inventors property rights to their discoveries. In such a world, inventors would have every incentive to be secretive and to guard jealously their discoveries from competitors [because those discoveries] could, of course, be copied with impunity. “By contrast, in a world where property rights in invention were protected, the situation would be very different. Inventors would now feel free to promote their discoveries as widely as possible so as to maximize returns either from commercializing their ideas themselves or from [licensing] rights to the idea to others. The protections offered by the patent system would thus be an important stimulus to the exchange of technological information in and of themselves. Moreover, it is likely that the cross -fertilization that resulted from these information flows would be a potent stimulus to technological change. iv iv Naomi R. Lamoreaux and Kenneth L. Sokoloff, “Inventors, Firms, and the Market for Technology: U.S. Manufacturing in the Late Nineteenth and Early Twentieth Centuries,” Historical Paper 98, National Bureau of Economic Research, Cambridge, Mass., 1997. It’s more than just “likely.” Extensive research in the United States and other nations shows that patents have served as a powerful stimulant to technological knowledge sharing. A 2006 survey published by the French economists Francois Leveque and Yann Meniere, for example, found that 88 percent of U.S., European, and Japanese businesses rely upon the information disclosed in patents to keep up with technology advances and direct their own R&D efforts. v v Francois Leveque and Yann Meniere, “Patents and Innovation: Friends or Foes?” CERNA (Centre d’economie industrielle Ecole Nationale Superieure des Mines de Paris), December, 2006. Patents Don’t Block Innovation, They Promote It From the earliest days of the United States, patent and legal records show how inventors (including Thomas Edison) regularly kept abreast of developments in their fields. They did this by studying patent descriptions published by both the USPTO as well as by industry publications such as Scientific American, which was founded in 1845 by Munn and Company, the leading patent agency of the nineteenth century, expressly to spread new technological knowledge and facilitate the buying and selling of patents. For example, Elias E. Reis—inventor of a number of devices to exploit the heat generated by electrical currents—reported that when he read in the Official Gazette in 1886 about a patent issued to Elihu Thomson for a new method of electric welding, “there immediately opened up to my mind a field of new applications to which I saw I could apply my system of producing heat in large quantities.” vi In many industries, specialized journals kept readers informed about new patents of interest. vi See “Record of Elias E. Reis,” 8, Thomson v. Reis , case 13,971, box 1,845, Interference Case Files, 1836-1905, Records of the Patent Office, Record Group 241, National Archives, courtesy of B. Zorina Khan. In fact, new research in 2012 discovered that rather than blocking development, Thomas Edison’s seminal 1880 incandescent lamp patent ( No. 223,898 ) actually “stimulated downstream development work” that resulted in “new technologies of commercial significance [including] the Tesla coil, hermetically sealed connectors, chemical vapor deposition process, tungsten lamp filaments and phosphorescent lighting that led to today’s fluorescent lamps.” vii vii Ron D. Katznelson, “Inventing Around Edison’s Incandescent Lamp Patent: Evidence of Patents’ Role in Stimulating Downstream Development,” May, 2012, derived from: http://works.bepress.com/cgi/viewcontent.cgi?article=1073&context=rkatznelson Even the word “patent” signifies its social purpose of disclosure. It is derived from the Latin patent meaning “open,” and is the present participle of “pate¯re,” meaning “to stand wide open.” This explains the origin of the term “letters patent” (“letters that lie open”), which refer to the patent documents issued by the English Crown. These were not closed with a seal but were instead kept open, with the seal hanging at the bottom, notifying all not to infringe upon the patent. As with any economic and legal instrument, patents have the potential to slow innovation if their grant of exclusive rights is too broad. But the overwhelming preponderance of economic research and real-world experience demonstrate that, on balance, intellectual property rights tend to stimulate invention, economic growth, and the diffusion of new technological knowledge in every country where they exist. This fact by itself, however, does not explain why the U.S. patent system became a model for much of the world. To understand why it did—and how it helped build the most successful economy in the history of the world—we must examine the revolutionary design of the U.S. patent system itself and the ways in which it overcame the weaknesses of earlier patent systems. 1.2 The Weakness of Early Patent Systems Learning Objectives After completing this section, you will be able to Outline the history of patents from antiquity through the 1700s. Identify flaws in early European patent systems. History of Patents: 500 BC to the 1700s Given the commonsense logic of granting patents to stimulate invention, it comes as no surprise that patent- like incentives date all the way back to antiquity. In the ancient Greek city of Sybaris (located in what is now southern Italy) in 500 BC, “encouragement was held out to all who should discover any new refinement in luxury, the profits arising from which were secured to the inventor by patent for the space of a year.” viii viii Charles Anthon, “ A Classical Dictionary ,” Harper & Bros, 1841. The first formal patent legal institutions were developed in the Republic of Venice in the mid-1400s. The Venetian Statute of 1474 decreed that the inventors of new and useful devices would be protected from infringers and copiers for ten years so long as they disclosed the details of their inventions. Most Venetian patents were granted in the field of glass making, and when a large number of these glass makers emigrated to other countries in Europe, they sought similar protections from the local authorities. This is how the notion of patent rights, and their expression in patent legal systems, began to spread and gain acceptance throughout Europe. Initially, however, English and French monarchs used patents not simply to stimulate invention, but also to grant exclusive trade monopolies to those favored by the court. In the reign of Elizabeth I in the latter 1500s, some 50 patent monopolies were granted over the trade in such staples as salt, soap, starch, iron, and paper. Critics said these “enriched the monopolist and robbed the community” while doing absolutely nothing to stimulate new technology or industry. A growing public outcry ultimately forced Elizabeth’s successor James I to revoke these grants of trade monopolies in 1610. In 1624, the Statute of Monopolies formally repealed the practice and henceforth restricted patent rights solely to new inventions. European countries made several other important innovations in their early patent systems. In the mid-1500s, France became the first to publish patent descriptions from inventors who chose to submit them. England under the reign of Queen Anne (1702–1714) was the first to require inventors to submit a written description of their patent to “describe and ascertain the nature of the invention and the manner in which it is to be performed.” And in 1729, France began to publish abbreviated digests of patent descriptions, but these were intermittent and subject to delays of up to 60 years after the patents were originally granted. As might be expected, this lack of regularity limited the technological knowledge sharing that is one of the great benefits of a patent system. Flaws of Early Patent Systems Old World patent systems suffered from other major weaknesses as well. Patents for inventions imported from other countries were regularly granted, increasing the incentive for would-be patentees to copy the creative work of others rather than invent for themselves. And there was generally no systematic examination of patents by technical experts, in part because this was viewed as an intrusion upon the prerogatives of the Crown. But the biggest problem with early patent systems was that they all shared a tendency to reinforce the wealth and prerogatives of elites, not the welfare and productive capacity of the whole of society. In Britain, patents were favors granted “by grace of the Crown” and were often only secured through court connections. They were also “subject to any restrictions the government cared to impose, including the expropriation of the patent without compensation.” ix ix Op. cit., Khan. What’s more, patent application fees were prohibitively high—more than 11 times the per capita annual income of the average British citizen—which put the system out of reach of all but the wealthy. Yet ironically, in the parliamentary debates over the patent system, the exclusion of the “working classes” was regarded as one of the chief virtues of the British patent system. British patent law also severely limited the ability of inventors to sell or license the rights to their discoveries, as noted in a contemporary 1832 book entitled A Practical Treatise on the Law of Patents for Inventions . x This restriction, along with “working requirements”—these were regulations that forced patentees to manufacture products based on their patents within two or three years of issuance or lose their patent rights—limited innovation activity mainly to those who had the factories (or the ready capital to build them) needed to produce such products. x Richard. Godson, A Practical Treatise on the Law of Patents for Inventions and of Copyright, Saunders and Benning, 1832. Retrieved from Google books, at bit.ly/QmPhaZ These rules had two significant effects upon the British economy. They restricted innovation to only a small sector of the population rather than unleashing the creativity and productivity of the whole people. And they created a bias toward inventions that enhanced the market dominance of incumbent, capital-intensive industries rather than opening up new markets for the sorts of disruptive new industries that usually drive economic progress. “European societies were organized in ways that concentrated power in the hands of elites and facilitated [parasitic] rent-seeking by favored producers,” notes historian B. Zorina Khan. “The organization of invention was no exception. A society that restricts [invention] to elites can generate exceptional gains early on, but the initial spurt is unlikely to be maintained.” Indeed, the result in Britain was unbalanced and narrowly focused economic growth. Inventors faced high transaction and monetary costs, a limited market for their inventions, and a great deal of uncertainty. Diffusion of new technological knowledge was severely inhibited, and the rate of technological change was adversely affected as a result. Eventually, Britain’s initial leadership of the Industrial Revolution had more to do with its large existing commercial holdings and manufacturing base, and its vast stores of amassed capital, than with systemic or broad-based encouragement of innovation within British society. The Changing Tide The elitist nature of early patent systems reflected the feudal economic relations that dominated that era. But by the late eighteenth century, capitalist economies were beginning to emerge across Europe, and in Britain, nationwide lobbies of manufacturers and patentees called for an overhaul of the patent system to bring it in line with this new economy. The needed reinvention would come not from Britain, however, nor even from France, which had its own democratic revolution soon after America’s. Instead, it took place in the newly liberated United States, where a vibrant capitalism unburdened by centuries of entrenched feudalism was developing. This, then, is the story of one of the most admired of all American inventions—the modern democratized patent system, now used widely throughout the world. 1.3 America’s Uniquely Democratic Patent System Learning Objectives After completing this section, you will be able to Explain the role of the Founding Fathers in developing the U.S. patent system. Explain the six unique features of the U.S. patent system. Never mind that intellectual capital accounts A Patent System For Everyone Before reading this section, please watch this overview video covering why America developed the world’s first patent system for the common man, and what we got out of it as a result (hint: the strongest economy on the face of the earth). Never mind that intellectual capital accounts for 55 percent of total U.S. GDP today. xi Or that it represents up to 80 percent of the market value of all public companies in the U.S. xii To most citizens today, patents and other intellectual property are inscrutable mysteries. But to America’s Founding Fathers, they were matters of the highest national importance. xi Kevin A. Hassett and Robert J. Shapiro, “ What Ideas Are Worth: The Value of Intellectual Capital and Intangible Assets in the American Economy ,” Sonecon, 2012. xii “Intangible Asset Market Value,” Ocean Tomo, derived from http://bit.ly/bAPJVH The Challenge Facing the Founders The people who led the revolution and were later tasked with writing a Constitution were not concerned simply with creating lasting political structures that could defend the hard-won freedom and sovereignty of the newly liberated colonies. They also struggled to stimulate the rapid growth of industry to ensure the new nation’s economic survival. The survival of the United States of America was far from certain in those days. It was a backward agrarian economy, dependent on imports and lacking major domestic industry, with a population of barely three million inhabitants. Britain, meanwhile, with whom the United States had just fought a war and would soon fight another, had three times the U.S. population, boasted the most powerful economy on Earth, and was the unrivaled leader of the emerging Industrial Revolution. It was, therefore, a critical task of the leaders of the new American nation to design institutions—including a patent system—that would encourage economic activity and investments to spur the growth of America’s primitive economy. It’s important to note that although the Founders deeply believed in democratic ideals of government, they were not wild-eyed idealists. They were very practical people who faced an overwhelming challenge: How do you build a national economy from scratch, one that can prosper without British imports? To do that, they needed to mobilize every asset they had. Unlike Britain, however, America had no significant capital or commercial assets. In fact, the American standard of living at that time was actually lower than in many of their South American neighbors. xiii All America had was abundant, but still untapped, natural resources, and a population widely regarded in the world as uniquely enterprising and independent minded. xiii Stanley Engerman and Kenneth Sokoloff,“ Factor Endowments, Institutions, and Differential Paths of Growth Among New World Economies ,” in Stephen Haber (ed), How Latin America Fell Behind, Stanford University Press, Palo Alto, California, 1997. Ours was the world’s fastest-growing population, doubling in size every 20 years. Americans were also widely literate (albeit mostly lacking in higher education) and informed by what Washington Irving called “the general diffusion of knowledge.” Most important, unlike the tenant farmers and laborers who made up the bulk of England’s rigid class society, the vast majority of Americans were free-holding small farmers, merchants, shopkeepers, artisans, and mechanics—the forerunners of what we today call the middle class—who were possessed with what publisher Hezekiah Niles called “a universal ambition to go forward.” This was America’s principal asset, their ace in the hole. And men such as George Washington, Thomas Jefferson, and James Madison knew they had to find a way to unleash the creative and productive potential of these independent citizens if the country was to industrialize and survive. Incentives Needed to Spur Economic Growth As Jefferson wrote to his daughter Martha in 1787, it was precisely because America was bereft of Europe’s vast resources and left to its own devices that “we are obliged to invent and execute; to find means within ourselves, and not to lean on others.” But how to do that? From the historical record, it appears that the Founders quite consciously sought to construct a patent system that would do what no other patent system in the world had ever done before—namely, stimulate the inventive genius and entrepreneurial energy of the common man. As noted earlier, the first thing they did was to affirm inventors’ and authors’ rights in the U.S.Constitution itself. Although the intellectual property clause was ultimately adopted by unanimous consent of the delegates on September 5, 1787, there had been some debate about the issue. Thomas Jefferson in particular had expressed reservations about the wisdom of granting “temporary monopolies” (i.e., patent rights), given that Americans had just waged a bloody war of independence to overthrow the British monopoly of trade and political power. But as other delegates noted, and Jefferson eventually came to realize, a monopoly of trade is a far cry from the temporary incentives granted to inventors in return for the benefits they provide society. “How can the exclusive right of an invention be compared with a monopoly in trade?” D.P. Holloway, a Commissioner of Patents, would later argue in his 1863 annual report to Congress. “How can the exclusive privilege to sell salt in Elizabeth’s time, which added not one bushel to the production, but which enriched the monopolist and robbed the community, and the exclusive right of Whitney to his cotton gin, which has added hundreds of millions [of dollars] to the products and exports of the country, be both branded, with equal justice, with the odious name of monopoly?” xiv xiv United States Patent Office, Annual Report of the Commissioner of Patents 1863. Retrieved from Google Books at http:// bit.ly/Meh0Pv In the words of Louis Wolowski, Chair of Industrial Economics at the Conservatoire des Arts et Métiers: “[Inventors’] rights under patents, are called ‘monopolies’ only from the poverty of language, which has failed to express in words a distinction which no less clearly exists.” The Founders understood this distinction clearly. “Rather than monopolists,” says historian Khan, “patentees were viewed as beneficent contributors to progress, and the consistent goal of those who shaped the system was to encourage domestic ingenuity, whatever the social class of the inventor.” xv xv Opt. cit., Khan. Or as James Madison put it in Federalist Paper 43, “The public good fully coincides with the [patent rights] of individuals.” Creating a New Type of Patent System The real genius of the Founders, however, lay in the way they consciously integrated democratic principles into the design of the world’s first modern patent system—principles that had a profound impact on the pace and direction of U.S. economic growth. These were reflected in six fundamental innovations in our patent system that departed from European practice. Low Fees: Making Patents Affordable The original patent law passed by Congress on April 10, 1790, deliberately set patent fees to a level any ordinary citizen could afford—initially $3.70, but three years later raised to $30. This was still less than 5 percent of the rate in Britain. Patent fees remained $30 for the next 70 years, ensuring that virtually any citizen could participate in the Industrial Revolution. The results were dramatic. Whereas most of Britain’s handful of inventors came from privilege, the vast majority of America’s thousands of inventors came from humble beginnings. They included farmers, factory workers, merchants, mechanics, and other artisans. Of the 160 so-called “great inventors” of nineteenth-century America, over 70 percent had only a primary or secondary school education. Many had no formal schooling at all. And some of the most famous names in American invention—Matthias Baldwin (locomotive), George Eastman (roll film), Elias Howe (sewing machine), and Thomas Edison (electric light and phonograph)—had to leave school early to support their families. What’s more, in another sign of economic democratization, most U.S. inventors had no formal scientific or technical training. They had only the general knowledge common to citizens of the day, plus whatever they taught themselves. What distinguished them was their ingenuity in applying that general knowledge to the practical problems of daily existence, and then exploiting the commercial opportunities that arose as a result. In short, they were entrepreneurial. The rapid growth of inventive activity during early American industrialization was characterized by a disproportionate increase in the involvement of segments of the population with relatively common sets of skills and knowledge,” note Sokoloff and Khan. “Rather than being accounted for by an elite who possessed rare technical knowledge or commanded large amounts of financial resources, the rise in patenting coincided with a broadening of the ranks of patentees to encompass many individuals, occupations, and geographic districts.” xvi xvi Kenneth Sokoloff and B. Zorina Khan, “ The Democratization of Invention During Early Industrialization, 1790O1846 ,” Working Paper No. 578, Department of Economics, University of California, Los Angeles, December, 1989. Making the patent system inexpensive invited everyone’s participation. In the words of Englishman John Standfield, quoted in an 1880 issue of Scientific American , “The cheap patent law of the United States has been and still is the secret of the great success of that country.” Simplifying Application Procedures The Founders greatly simplified administrative procedures in applying for a patent. This was no small thing when you consider that British applicants were forced to seek approval from seven different offices, and then twice—twice!—obtain the signature of the King. If they wanted a patent that covered Scotland and Ireland as well, they needed approval from ten more offices. British patent procedures were so Byzantine, in fact, that author Charles Dickens wrote a spoof of them entitled A Poor Man’s Tale of a Patent , in which his main character, an inventor, is forced to seek approvals from 34 offices, some of which had been abolished years before and no longer existed. Obviously, few inventors could hope to run this gauntlet successfully unless they had the wherewithal to hire very expensive patent agents to assist them. In the United States, on the other hand, applications only needed the approval of a single patent office, which created repositories throughout the country where inventors could drop off their applications and models and have them forwarded to the patent office at government expense. Rural inventors could even apply for a patent through the mail—postage free! This last perk for rural inventors turned out to have a big impact on the course of U.S. economic development. While most British industrial breakthroughs were confined to London or other big cities, U.S. inventions were widely distributed across the country, in urban and rural areas both. The result was broader- based economic growth and less income inequality in the United States. Spreading New Technological Knowledge Another unique feature of the U.S. patent system was its systematic effort to spread new technological knowledge throughout society, thereby creating a virtuous circle of innovation begetting more innovation. In Britain, patents were only open to public inspection after paying a fee, and until 1852 were not even officially printed, published, or indexed. In France, printed information about patents was limited to brief titles in patent indexes, intermittently published and only available in the office in which these had been originally filed. By contrast, the first U.S. patent law explicitly stated that “copies of patent Specification together with similar Models [are] to be made at the public Expence and lodged in each state.” xvii In addition, as noted in the previous section, a plethora of publications by government and industry enabled any citizen with an interest to keep abreast of the latest patented technologies. xvii Patent Act of 1790, HR-41, Examining Patents for Validity In a very crucial departure from Old World practice, the Founders created the world’s first examination system for patents to ensure their novelty , non-obviousness , and utility . The examinations were initially conducted by a committee composed of the Secretary of State (Thomas Jefferson), Secretary of War (Henry Knox), and Attorney General (Edmund Randolph). But this was found to be cumbersome, so in 1793 a simple registration system was established. It turned out, however, that without the examination of applications for novelty, non-obviousness, and utility, the validity of issued patents began to be questioned. So the reforms of the 1836 Patent Act specified that henceforth applications would be scrutinized by technically trained examiners to ensure that the invention represented a genuine advance in the state of the art. For the first time anywhere in the world, the criteria for granting a patent depended solely upon the merits of the application rather than the identity or the mere say-so of the inventor. The situation was very different in Europe. In France, the following caveat was printed on each patent: “The government, in granting a patent without prior examination, does not in any manner guarantee either the priority, merit or success of an invention.” Imagine trying to interest a group of investors in your new invention with that kind of warning label attached to it! In Britain, meanwhile, the lack of any examination of patent validity made the purchase of a patent right highly speculative and costly, thereby limiting investment in new technology. By contrast, says Khan, “the U.S. examination system reduced uncertainty about the validity of patents, and provided [interested parties] with a signal of [their] potential value.” This proved to be crucial in facilitating the growth of an extensive market in the sale and licensing of valuable patent rights—the first large-scale market of this type in the world. No “Working Requirements” Reduced Monopoly Control The fifth distinguishing feature of the U.S. patent system was the lack of any sort of “ working requirements .” In the debate over HR-41, the bill that became the first U.S. patent law in 1790, “the Senate suggested requiring patentees to make products based on the patent or license others to do so. But the House rejected this as an infringement of patentees’ rights.” xviii xviii Op. cit., Khan. Indeed, the Founders believed working requirements would only strengthen monopoly power and skew invention toward incumbent industry by limiting patents to those with the factories (or the capital to build them) needed to manufacture products from their inventions. xix xix B. Zorina Khan, “ Antitrust and Innovation Before the Sherman Act ,” Antitrust Law Journal, No. 3, 2011. In short, the Founding Fathers of this nation deliberately and quite consciously created what we now call “ non-practicing entities ” (NPEs) in order to expand the pool of inventors in their then backward economy to include ordinary citizens without the wealth or resources to commercialize their own inventions. And it worked, leading to a dramatic surge in innovation in nineteenth-century America as large numbers of ordinary citizens started inventing and then licensing their discoveries to enterprises for commercialization. By 1865, the U.S. per capita patenting rate was more than triple that of Britain’s, according to the annual reports from the commissioners of patents in both countries, and by 1885, it was more than quadruple that of Britain. Each U.S. patentee was also far more prolific than their British counterpart, so by mid-century, the United States was patenting five times the number of inventions as Britain each year, even though the populations were then equal in size. Creating a Market for New Technology The sixth unique feature of the U.S. patent system—and along with the refusal to impose working requirements, the one that had the greatest impact on future U.S. economic growth—was “an explicit provision for the sale of patent rights [that] both the courts and the U.S. Patent Office acted to facilitate.” xx xx Naomi R. Lamoreaux and Kenneth L. Sokoloff, “ Inventive Activity and the Market for Technology in the United States: 1840O1920 ,” Working Paper 7107, National Bureau of Economic Research, Cambridge, Mass. 1999. Why facilitate the buying and selling of patents? Because doing so enabled ordinary worker or farmer inventors without the capital to commercialize their own discoveries to still participate in inventive activity and earn income by licensing or selling their patents to enterprises that could. This ability to license patent rights (along with the low application fees) turned inventing into a new career path for thousands of poor but technically creative citizens. xxi It also proved to be a powerful means of mobilizing capital for investment in new technologies and their commercialization into new products and services for society. xxi B. Zorina Khan, “ Institutions and Technological Innovation During Early Economic Growth: Evidence From the Great Inventors of the United States, 1790-1930 ,” Working Paper 10966, National Bureau of Economic Research, Cambridge, Mass., 2004. That patents could be used as tradable assets by non-practicing entities without the wealth to commercialize their own discoveries was a wholly unique feature of the American patent system. By 1880, 85 percent of all U.S. patents were licensed by their inventors, compared with 30 percent of British patents. xxii xxii B.Zorina Khan, The Democratization of Invention Patents and Copyrights in American Economic Development, 1790-1920, Cambridge University Press, 2005. Patent licensing, in fact, was the principal means by which new discoveries were commercialized in the decades before the early twentieth- century emergence of in-house corporate R&D departments. Publications such as Scientific American were founded specifically to facilitate the trade in patents, and it regularly featured lists of new and interesting patents, which commercial enterprises then licensed or purchased to use in their product development efforts. American Bell Telephone’s new product pipeline, for example, operated like most others at the time. According to its 1894 annual report, the company’s R&D department licensed 73 patents from outside inventors, while developing only 12 from its own employees. Thomas Blanchard was a typical inventor-licensor. He was the son of a small farmer who invented and patented a mechanical tack-maker in 1806 that could fabricate five hundred tacks per minute, each superior to tacks made by hand. He sold the rights to his machine for $5,000, quite a sum in those days. He then invented a lathe to produce uniform gun stocks, and the patent he received for it enabled him to attract investors for the production of those gun stocks for the local Boston market. Blanchard also leased his patent rights to gun producers nationwide, as well as to manufacturers of tool handles and wheel spokes. The income he generated from patent licensing enabled him to make inventing his full-time career. He went on to invent a wood-bending machine, an upriver steamboat, and a steam wagon that was used until the introduction of railroads in the United States, and received a total of 25 patents during his career. According to a 2013 Congressionally mandated Government Accountability Office (GAO) report on NPEs, “History is filled with examples of successful inventors who did not develop products based on the technologies they patented.” It specifically cited the case of Elias Howe, who patented a method of making a lockstitch but did not produce sewing machines. Instead, Howe licensed his patents to the Singer Company, which then deployed Howe’s invention in its sewing machines. xxiii xxiii “ Intellectual Property: Assessing Factors that Affect Patent Infringement Litigation Could Improve Patent Quality ,” U.S. GAO, August 2013. Patent licensing, scholars have found, was facilitated by an array of intermediaries—lawyers, venture financiers, and patent licensing agents—who “lowered the transaction costs and improved the efficiency” of the trade in and commercialization of patented technology. “By enabling, indeed encouraging, inventors to focus on what they did best [i.e., invention], this division of labor gave rise to the most technologically fertile period in American history.” xxiv xxiv Naomi Lamoreayx and Kenneth Sokoloff, “ Intermediaries in the U.S. Market for Technology, 1870-1920 ,” Working Paper No. 9017, National Bureau of Economic Research, Cambridge, MA. June, 2002. The Positive Effects of Licensing The Founders’ decision to foster NPEs and patent licensing proved crucial to America’s rapid technological progress and economic growth. Indeed, patent records from the nineteenth century reveal that more than two-thirds of the “great inventors” of the Industrial Revolution, including Thomas Edison and Elias Howe, were NPEs who specialized in invention and licensed some or all of their patents to outside enterprises for development into new products. xxv xxv B.Zorina Khan and Kenneth L.Sokoloff, “Intellectual Property Institutions in the United States: Early Development and Comparative Perspective ,” World Bank Research Workshop, July 17-19, 2000 Had the United States followed the approach of older European patent systems and limited patent rights solely to inventors who made or sold products—or prevented them from licensing their patents—America might not have even had an Industrial Revolution. In any event, the result of this division of labor between invention and production was exactly as Adam Smith predicted: “The growth of market trade in patents raised the returns to invention and encouraged a division of labor whereby technologically-creative individuals increasingly specialized in their comparative advantage—invention,” noted Lamoreaux and Sokoloff. “It was the expanded opportunities to trade in patented technologies that enabled the independent inventors of this golden age to flourish—and that stimulated the growth of inventive activity generally.” The benefits of that division of labor remain visible today, embodied in the thousands of university and other NPE patents licensed by companies large and small each year, as well as by the positive U.S. balance of trade in patent licensing, estimated to be worth at least $150 billion annually as of 2006. More than 5,000 new products and 7,000 new companies have been created with the help of university NPE patents alone in the last 30 years. xxvi And licensors of patented technology help the United States maintain its technology leadership in critical economic sectors. xxvi Joseph Hornett and David Johnson, Purdue Research Foundation. Derived from: bit.ly/O7iA18 A New Species called “Patent Trolls” To be sure, there is new a species of NPE known as “patent trolls” who use low-quality patents to extort so-called “license fees” from small businesses unable to pay the cost of standing up to them in court. But their activities have nothing in common with real patent licensing. Typically, these patent owners send form letters to hundreds, or in some cases thousands, of random small businesses, claiming with little or no evidence that they are “infringing” their patents. These letters then demand so-called “licensing fees” ranging from one to several thousands of dollars to avoid a patent infringement lawsuit that could cost those businesses far more to defend against in court—even if the business owner is innocent of any infringement. Beginning in mid-2013, a torrent of bad faith demand letters began targeting small businesses, sparking wide protest. The National Federation of Independent Businesses (NFIB) and many other business groups and trade associations demanded action, and Washington responded in 2014 with several pieces of proposed reform legislation. By early 2015, the Federal Trade Commission (FTC) had acted against one sender of bad faith demand letters, and federal legislation to rein in such abuses seemed likely to pass. At the state level, meanwhile, by early 2015, 15 states had enacted laws to curb abusive patent demand letters, and 11 others were actively considering similar bills. In addition, the attorneys general of several states have used consumer protection laws against making false claims to force these “patent trolls” to stop sending their extortionist demand letters. These abusive patent litigants should not be confused with legitimate NPEs, however, whose primary business is invention and technology licensing, not extorting so-called “license fees” from innocent businesses. Patent licensing facilitates the transfer and commercialization of technology into new products and services and promotes U.S. economic growth. A Patent System for Everyone In sum, these six unique features of the U.S. patent system—low fees, simplified procedures, examination of applications by trained experts, systematic disclosure of new technological knowledge, lack of “working requirements,” and encouragement of robust trade in patent rights—all had a powerfully beneficial impact on the nation’s economic growth. But none of that would have been possible were it not for the broad-based democratic rule of law in the United States and the critical role played by the U.S. legal system in interpreting and enforcing America’s revolutionary patent laws. 1.4 The Role of the U.S. Legal System Learning Objectives After completing this section, you will be able to Describe the differences between U.S. and European patent laws. Describe the history of patent litigation in the United States. U.S. Patent Law vs. European Patent Law Just as with any other property right, patent rights would be meaningless without the ability to enforce them in court. And from the earliest days of the patent system, says Khan, “Our legal system remained true to the Constitution in the belief that the defense of rights in patented invention was important in fostering industrial and economic development.” In Britain and other European countries, patents were viewed as “pernicious monopolies that restricted community rights and [Had] to be carefully monitored and narrowly construed.” xxvii The enforcement and interpretation of patent laws by the courts in Europe also tended to be highly variable and dependent upon the whims of each individual judge. xxvii B.Zorina Khan, The Democratization of Invention: Patents and Copyrights in American Economic Development, 1790-1920 , Cambridge University Press, 2005. In the United States, however, early courts treated inventors’ patent rights with deference, just as they did the rights of other property owners. Famed Supreme Court Justice Joseph Story repeatedly declared that patent rights were “sacred” and were the just reward for inventive ingenuity. As he noted in Lowell v. Lewis (1817), “the proper duty of the court” is to ensure that “wrongdoers may not reap the fruits of the labor and genius of other men.” The relative uniformity and certainty of enforcement of patent rights by the courts also proved critical in encouraging capital to invest in commercializing those patent rights. Contrasting the patent laws and policies of the United States and Britain, Supreme Court Justice Henry Baldwin went to some lengths in Whitney v. Emmett (1831) to show how English courts saw patents as a zero-sum trade-off between private rights and the public good. The explicit intention of U.S. patent law, however, was “to benefit the inventor, in the belief that maximizing individual welfare leads to maximum social welfare.” Nonetheless, U.S. intellectual property laws did try to strike a balance between the needs of the many and the few. “Patent laws ensured the security of private property rights in invention. However, it was also necessary to balance the just claims of inventors against the dangers of exclusive monopolies that might restrict the scope of current and future invention.” xxviii xxviii Op. cit., Khan. Changes in U.S. Patent Law Through the Years Over the years, of course, that balance has moved back and forth between relatively stronger versus weaker enforcement of patent rights. With the rise of the robber barons in the late nineteenth century, government and the courts increasingly viewed patents through the prism of antitrust, in some cases even compelling large firms like IBM to license their patents to competitors. Then with the advent of the high-tech revolution in the 1980s, antitrust concerns faded and the courts began once again to view stronger patent rights as helpful in fostering innovation. Interestingly, the U.S. legal system has always operated on the theory that the best way to achieve the proper balance between private rights and public interest was not through government decree, centralized management, or compulsory licensing but rather through the decentralized decision making and market interactions of inventors themselves. The court’s role was to resolve the inevitable conflicts that arose, on a case by case basis. Throughout all the twists and turns in patent enforcement over the centuries, however, the federal courts have remained unwavering on four key principles of U.S. patent law. An “Explosion” of Patent Litigation? Patent litigation, of course, has always been an integral feature of the U.S. patent system. The first patent case on record was that of Benjamin Folger, whose patent for the production of candles was invalidated by the district federal court for New York in 1792. This was merely the first of many hundreds (and eventually thousands) of cases in which patent litigation served the important function of settling either the validity or the disputed ownership of the rights to critical new technologies—the litigation between telephone inventors Alexander Graham Bell and Elisha Gray being perhaps the most famous case in point. By doing so, the courts provided greater certainty regarding the value of such rights to entrepreneurs and investors alike. Today, some critics contend that an “explosion of patent litigation” unlike any in history is harming business and diverting resources better spent on innovation. No responsible observer would deny that the courts have seen an increase in patent infringement suits in recent years, just as they have seen a rise in personal injury claims and product liability suits. But that said, the evidence shows that the rate of patent litigation today is actually below historical norms. According to USCourts.gov figures, the number of patent infringement suits filed in the United States increased 59 percent between 2001 and 2011—from 2,520 cases in 2001 to 4,015 cases in 2011. Meanwhile, the number of patents granted in that same period increased by only 35 percent, which supports the view that patent litigation has become more frequent over the last decade as the role and value of intellectual property has increased in the Knowledge Economy. Statistics from USCourts.gov show an even sharper rise in the number of patent suits filed in 2012, to 5,189 cases. But analysts attribute most of this increase to the anti-joinder provisions of the Patent Act of 2011, which curtailed the practice of naming multiple defendants in a single infringement suit. According to Carla Rydholm of the patent analytics firm Lex Machina, “Plaintiffs must [now] meet more stringent requirements to file a case against multiple defendants. So instead of Plaintiff X filing one case naming 20 defendants, Plaintiff X might file 20 lawsuits (one per defendant) each with unique civil action numbers.” When looked at over the longer term, however, it turns out that 96 percent of all the increase in patent infringement suits since 1991 can be explained by a corresponding increase in patents granted, reports the PricewaterhouseCoopers’s 2013 Patent Litigation Study. xxix xxix Http://www.pwc.com/en_US/us/forensic-services/publications/assets/2012-patent- litigation-study.pdf In case you’re wondering if the increase in patents granted is itself a sign of a patent system being increasingly gamed by speculators wanting to cash in on the new “patent gold rush,” note that the average number of patents issued per billion dollars of GDP has remained at or below the same level—13 patents per billion dollars of GDP—since 1963. xxx xxx Sean Connolly, “Patent Litigation Rates: What They Tell Us and What They Don’t,” derived from: http://connollyip.com/patent-litigation-rates-what-they-tell-us-and-what-they-dont/ Interestingly, although the number of suits filed has increased in rough correlation to patent grants, the number that actually go to trial has remained fairly constant over the last 30 years. About 90 percent of the suits filed each year are abandoned or settled. Of the three hundred that remain, two-thirds never go to trial, and are adjudicated on summary judgment (of noninfringement in most cases). The nation is thus left with, at most, between 90 and 112 patent infringement trials per year—exactly the same number that went to trial 10, 20, and even 30 years ago. xxxi xxxi Gene Quinn, “Patent Litigation Statistics: 1980- 2010, IP Watchdog , derived from: http://www.ipwatchdog.com/2011/08/02/patent-litigation-statistics-1980-2010/id=17995/ To be sure, there can be significant costs to business even in litigating and settling patent suits that never go to trial. But no one has shown that the relative cost of patent litigation today is higher than it was historically, or that the cost of patent litigation is more burdensome than other customary legal costs in business, especially the huge cost of regulatory compliance. The evidence does not suggest that patent litigation is “out of control” today. As retired Chief Judge Paul Michel of the U.S. Court of Appeals for the Federal Circuit, the main court for patent appeals since 1982, notes, “The level of patent litigation today is rather modest for a nation with two million active patents and hundreds of thousands of businesses competing against each other.” History supports Judge Michel on this point. The estimated 124-plus smartphone patent suits filed between 2009 and 2012 xxxii are less than one- quarter the number of patent suits filed during the first “Telephone Wars” of Alexander Graham Bell’s time. Back then, the American Bell Telephone Company and its successor, AT&T, litigated 587 patent cases alone. xxxiii xxxii http://en.wikipedia.org/wiki/Smartphone_wars. xxxiii “The Telephone Cases,” Wikipedia, http://en.wikipedia.org/wiki/The_T elephone_Cases. Even more surprising, given the common belief in a patent litigation “explosion” today, patent and legal records from the golden age of invention during the mid-nineteenth century U.S. Industrial Revolution show that the patent litigation rate at that time—defined as the number of patent suits filed in a decade divided by the number of patents issued in that decade—reached 3.6 percent. xxxiv xxxiv B. Zorina Khan, “ Property Rights and Patent Litigation in Early Nineteenth-Century America ,” Journal of Economic History, 1995, vol. 55, issue 01, pages 58-97. In contrast, USCourts.gov figures show the patent litigation rate during the decade 2001 to 2011 was less than half that—only 1.52 percent. From 2002 to 2012, reflecting the increased suits but also the increased (276,788) patents issued, the litigation rate was 1.57 percent. Over the entire period from 1790 to 1860, the patent litigation rate averaged 1.65 percent. Today’s smartphone wars, then, are simply “back to the future” when it comes to the ways in which disruptive new industries are developed. Historians have noted that every major industrial breakthrough of the last 150 years—from the development of the sewing machine, telephone, automobile, radio, aircraft, medical stent, and even disposable diaper industries, to the birth of the semiconductor and Internet e-commerce industries—witnessed exactly the same surge in patenting and patent litigation that we see in today’s smartphone field. xxxv xxxv Adam Mossoff, “The Rise and Fall of the First American Patent Thicket: The Sewing Machine War of the 1850s, ” Arizona Law Review , Vol. 53, pp.165-211,2011. And just as with smartphones today, the most competitive technology arenas have always been the most litigious. In Edison’s time, the inventors of electrical discoveries were four times more likely than other inventors to be involved in patent litigation, and accounted for 41 percent of all patent suits filed during that period. xxxvi xxxvi B.Zorina Khan, The Democratization of Invention: Patents and Copyrights in American Economic Development, 1790-1920, Cambridge University Press, 2005. In any event, by early 2015, it had already become clear that a noticeable decline in patent litigation was under way. Most analysts attributed the decline to a series of U.S. Supreme Court rulings in 2014 limiting the patentability of software and increasing the ability of the courts to impose sanctions on abusive litigants, which will be discussed later in this chapter. Also driving this decline in litigation was the availability of new post-grant review proceedings under the new America Invents Act, which allow third parties to challenge patents and, if the evidence so warrants, have their claims invalidated by the USPTO’s Patent Trial and Appeal Board. Although patent litigation is costly, the historical record suggests that it serves a vital function by settling the validity and disputed ownership of patent rights so these can be commercialized into new products, new services, and new medical treatments. This is, in fact, the proper role of the courts. 1.5 What the U.S. Patent System Wrought Learning Objectives After completing this section, you will be able to Explain the effects of the U.S. patent system on American economic development. Describe trends in U.S. patenting over the years. Creating the World’s Most Successful Economy In 1630, the puritan John Winthrop, future governor of Massachusetts colony, declared that “We shall be as a city upon a hill, the eyes of all people are upon us.” One hundred and fifty years later, the Founders of the United States of America proved Winthrop right, offering the world a vision of liberty and democratic governance that continues to inspire people to this day. As noted previously, the men who led the Revolution and wrote the Constitution were not wild-eyed revolutionaries. They were eminently practical people who managed to create the longest- living modern democratic political and economic system on the planet. In other words, they must have done something right. And one of those things was surely the patent system they created. Because almost from the moment of its inception, it began to spark innovation and economic growth on a scope and scale never before seen in the world. Only two months after America’s first patent law was signed in 1790, in fact, Thomas Jefferson himself noted that it had “given a spring to invention beyond my conception.” Within 13 years, America surpassed Britain—until then, the unrivaled leader of the industrial revolution—in the number of new inventions patented, even though Britain still had more than twice America’s population. By 1870, as noted earlier, the United States was patenting more than five times the number of inventions as Britain, although their populations were by then roughly equal in size. At first, most British observers were dismissive of American innovation efforts, declaring that the former colony would never be able to progress beyond the simple imitation of superior European technologies. But eventually Britain and other nations took note of the way the U.S. patent system seemed to be stimulating invention and economic growth at an unheard-of pace. Sir William Thompson, a British inventor and scientist attending the 1876 Centennial Exhibition in Philadelphia, looked at the amazing array of American inventions—including Bell’s telephone, the Westinghouse airbrake, Singer’s sewing machines, and Edison’s improved telegraph—and had this to say: “If Europe does not amend its patent laws, America will speedily become the nursery of useful inventions for the world.” xxxvii xxxvii Scientific American , October 21, 1876, courtesy of B. Zorina Khan. Meanwhile, the Swiss Commissioner in attendance, the shoe manufacturer Edward Bally, offered a similar warning to his Old World countrymen: “American industry has taken a lead which in a few years may cause Europe to feel its consequences in a very marked degree.” Then, there’s Japan’s Assistant Secretary of State Korekiyo Takahashi, who visited the U.S. Patent Office. Upon his return home, he said, “What is it that makes the United States such a great nation? We investigated, and we found it was patents. And we will have patents.” Even the British jurist Sir Henry Sumner Maine, who had once argued that “the establishment of the masses in power is the blackest omen” for the future of invention, later changed his tune. He conceded that the U.S. patent system was “one of the provisions of the Constitution that have most influenced the destinies of the American people” and that it had made the United States “the first in the world for the number and ingenuity of [its] inventors”. xxxviii xxxviii Henry Sumner Maine, Popular Government , courtesy of B. Zorina Khan. As historians Lamoreaux and Sokoloff noted, “[Foreign] observers attributed much of the country’s rapid technological progress to its distinctive patent system. Quite revolutionary in design at inception, the U.S. patent system came to be much admired for providing broad access to property rights in new technological knowledge and for facilitating trade in patented technologies. These features attracted the technologically creative, even those who lacked the capital to directly exploit [i.e., commercialize] their inventions . . . and also fostered a division of labor between the conduct of inventive activity and the application of technical discoveries to actual production. It is no coincidence that Britain and many other European countries [later] began to modify their patent institutions to make them more like those of the Americans.” xxxix xxxix Naomi R. Lamoreaux and Kenneth L. Sokoloff, “ Financing Innovation in the United States: 1870 to Present ,” MIT Press, Cambridge, Mass. 2007. Every Breakthrough Spurs Patenting Spikes The patent system’s central role in fostering innovation can be seen in the patenting spikes that occur with every major industrial breakthrough. A major surge in patenting took place in the 1880s, for example, when the number of new patents issued each year jumped 56 percent to about 20,000, compared with the 12,000 issued yearly during the previous decade. This patent boom corresponded with rapid advances in the emerging railroad, telegraph, telephone, and electric light and power industries that signaled the industrialization of the U.S. economy. The next sharp surge in patent issuances began around 1902 and lasted until 1916 or so, when the number of patents granted doubled from 20,000 per year to around 40,000 per year. This was the period of the newborn automobile and aircraft industries’ most rapid early-stage growth. Patenting levels then remained relatively stable at about 40,000 per year until around 1960 or so, when the revolution in plastics and other synthetic materials along with boom-time growth in the aerospace and computer industries pushed patenting levels to 60,000 per year. There they remained until the mid- 1980s, when the personal computer and emerging high-tech industries of Silicon Valley began to power the whole of the U.S. economy and propel us toward the age of the Internet. Patenting levels then rose to around 80,000 to 100,000 yearly With the rise of the Internet, social media, mobile telephony, and smartphones over the last two decades, the number of patent applications filed each year with the U.S. Patent and Trademark Office (USPTO) has surged fourfold. In 2014, the USPTO received 578,802 applications, finding 300,678 of these applications worthy of receiving a patent. This is but the latest spike in innovation and patenting. Clearly, whenever the United States has undergone a major industrial renaissance during which technology advances lead not only to the birth of new industries, but also to the reshaping of existing ones, patenting levels rise dramatically. It is no surprise, therefore, that Silicon Valley, midwife of many of the new Knowledge Economy industries of the past 60 years, is home to less than 1 percent of the nation’s population but earns 12 percent of its patents each year. The Valley is now the site of a new USPTO satellite office serving high-tech innovators there. xl xl “ Silicon Valley wins in securing U.S. patent office ,” San Francisco Chronicle, July 3, 2012. The patent system has also been crucial in facilitating the growth of new start-up businesses, with 67 percent of entrepreneurs reporting that they find patents valuable in obtaining venture financing. xli This is important because although large companies contribute enormously to American innovation and industrial growth through their in-house research and development operations as well as via their partnerships with research universities, start-up companies play a particularly strong role in the creation of entirely new industries. Indeed, virtually every innovative new industry of the last 150 years—From the telegraph, telephone, and electric power industries of the 1800s, to the auto, aircraft, materials, and aerospace industries of the twentieth century, to the semiconductor, personal computer, software, biotech and Internet e-commerce industries of the last 60 years—was launched by an entrepreneurial start-up company. xli “ Patenting by Entrepreneurs: The Berkeley Patent Survey Part III of III ,” PatentlyO, July 21, 2010. The Founders would not be surprised by this. They created the world’s first democratized patent system, after all, for a reason: to stimulate the ingenuity of the common man. They had asked themselves a question—the same question reiterated two generations later by Supreme Court Justice Joseph Story when he spoke before an audience of ordinary mechanics: “Ask yourselves, what would be the result of one hundred thousand minds ... urged on by the daily motives of interest, to acquire new skill, or invent new improvements.” xlii xlii Reported in American Jurist and Law Magazine , vol. 1 (1829), courtesy of B. Zorina Khan. The result was the most successful economy on the face of the earth. Patents and the American Dream It’s not only the economy that the patent system helped shape, but the culture and consciousness as well. As the eminent historian Gordon S. Wood observed in his 2010 book Empire of Liberty , “By the early nineteenth century, technology and prosperity were assuming for Americans the same sublime and moral significance that the enlightenment had reserved for the classical state and the Newtonian universe. Eli Whitney, inventor of the cotton gin, and Robert Fulton, creator of the steamboat, became national heroes.” And for the first time in human history, a nation had come to see its greatness not in empire or military might or royal lineage, but in its capacity for technological progress. There was nothing preordained about America’s economic success, no special “Yankee ingenuity” gene in their hereditary stock. As Scientific American noted in 1876, the United States advanced “not because we are by nature more inventive than other men. Every nationality becomes inventive the moment it comes under our laws.” Rather, the secret of America’s success was a uniquely democratic patent system that “added the fuel of interest to the fire of genius” in generations of ordinary citizens—and in so doing, helped in a very real way to give birth to the American Dream itself. Ironically, few people today even know the origin of the term “the American Dream.” In fact, it was coined in 1931, by the historian James Truslow Adams in his book Epic of America , and it is instructive to read what Adams meant by it: “The American Dream, that has lured tens of millions of all nations to our shores in the past century, has not been a dream merely of material plenty, though that has doubtless counted heavily. It has been much more than that. It has been a dream of being able to grow to fullest development as a man and woman, unhampered by the barriers which had slowly been erected in the older civilizations, unrepressed by social orders which had developed for the benefit of classes rather than for the simple human being of any and every class.” Only in America could a working class youth named Thomas Edison with less than three years of schooling develop himself into the world’s greatest inventor—a visionary who gave the world some of the most important technologies of late nineteenth- and early twentieth-century life. This is exactly what the Founders had in mind when they created the U.S. patent system. 1.6 Patent-Eligible Inventions Learning Objectives After completing this section, you will be able to Identify the characteristics of a patentable invention. Understand what is not patentable and why. What, Exactly, Can You Patent? Title 35 of the United States Code (the Patent Act) allows anyone who invents or discovers any new, non-obvious, and useful machine, manufacture, process, or composition of matter—or who makes an improvement of any of the above—to obtain a patent. xliii xliii 35 U.S.C § 101. These four kinds of patentable inventions fall into one of two categories: They are products or processes. xliv xliv Arthur R. Millerand Michael H. Davis, Intellectual Property: Patents, Trademarks, and Copyright in a Nutshell . (5th ed., p. 25). St. Paul MN: West Publishing Co., 2007. Product or Process? Products are physical things—whether they be machines (a new type of robotic welder), manufactures (an artificial knee made of titanium), or compositions of matter (a new chemical “superglue” for binding materials together). In this photo, Elon Musk observes the robotic arms in the Tesla Motors factory. Specialized manufacturing equipment like this are patentable products. Processes (or methods), on the other hand, are a means to an end—either a means of doing something new (being able to pay for purchases directly from your smartphone), or a new way of doing something old (using “pinch, swipe, and zoom” gestures on a touchscreen, rather than clicking drop-down menus, to manipulate text, music, and images on a smartphone). You Cannot Patent Ideas All patented inventions fit into one of these four categories: machine, manufacture, process, or composition of matter. But not everything that fits in one of these four categories can be patented. And the most important reason why one thing is patentable and another is not lies in the difference between ideas and applications. You cannot patent an idea for a better mousetrap—not unless it can be developed into a new, non-obvious, and useful machine, manufacture, process, or composition of matter that can actually accomplish the task. You may have a genius idea for faster-than-light travel, but that will not get you a patent unless you can outline how to develop a tangible process or device for actually doing so, in which case you can seek to patent it. Put another way, “talk is cheap” when it comes to securing a patent. The U.S. Patent and Trademark Office offers no judgment as to the wisdom or desirability of any particular invention—patent No. 2,882,858 for a bird diaper is certainly proof of that. But it absolutely will insist that every invention include a tangible device or process for achieving its intended purpose before it deems the invention worthy of a patent. Mathematical Formulas Not Patentable There are other discoveries that fall into the broad category of abstract ideas and are thus unpatentable. You cannot patent a mathematical formula. You cannot patent a law of nature, such as Einstein’s E=MC 2 . And you cannot patent natural phenomena like electricity (discovered by William Gilbert in 1600) or the Higgs particle that gives all matter its mass (discovered by researchers at the Large Hadron Collider on July 4, 2012). These all exist independently of human intervention, whether we have discovered them or formulated their rules yet or not, and must be freely available to all of humanity for its understanding and betterment. To restate the distinction, you cannot patent electromagnetism but you can patent a telegraph that uses electromagnetism to communicate rapidly over great distances, as Samuel Morse did in 1840 with patent no. 1647. And although you cannot patent light waves, you can patent a fiber optic wire that employs light waves to communicate even more rapidly and over greater distances, as Corning Glass researchers did in 1970 with patent no. 3,711,262. Can You Patent Computer Software? The boundary between ideas and applications might seem clear, but it has become blurred since the advent of computer technology 40 years ago, especially regarding the patentability of software. To learn more, watch this video from PBS Digital Studios about the first software patent ever awarded and to learn a bit about the debate around software patentability. Mixed Verdicts on Software Patentability The federal courts and the U.S. Supreme Court have tried to clarify the limits of patentability in the computer age. Three Supreme Court cases in particular—often called the “patent-eligibility trilogy”—reveal the evolution of its thinking about software patentability. In 1972, the Supreme Court held in Gottschalk v. Benson that an algorithm in a computer program—in this case, a mathematical procedure executed electronically that was similar to long division with paper and pencil—was in and of itself not patentable. Phenomena of nature, mental processes, and abstract intellectual concepts are the basic tools of scientific and technical research, the court noted, and therefore could not be patented lest it foreclose others from using the algorithm and thereby stifle rather than promote technological progress. Granting a patent in this case, the court said, would be analogous to having granted Samuel Morse a patent covering all possible uses of electromagnetism in communications, rather than for the specific method and apparatus he actually invented. The court made a point of saying, however, that its decision did not mean that computer software could not be patented—only that software whose only useful characteristic was an abstract algorithm could not be patented. The Supreme Court further refined its thinking on software patentability in the 1978 case Parker v. Flook . Unlike the attempt to patent all uses of an algorithm in the Benson case, here the use of a software algorithm was limited to a specific application—setting off an alarm during the catalytic chemical conversion of hydrocarbons. This was a specific and tangible use of an algorithm, but the Court still ruled the software unpatentable because it felt the application itself was not inventive. But once again, the Court left the door open: “Even though a phenomenon of nature or mathematical formula may be well known, an inventive application ... may be patented.” Three years later, the Supreme Court made its third attempt to define the patent-eligibility of software. In Diamond v. Diehr , the Court ruled that although algorithms by themselves are not patentable, a software program that used algorithms to govern the molding of raw synthetic rubber into cured precision products was in fact patentable because it involved “transforming or reducing an article to a different state or thing.” The Software Picture Blurs Even More Taken together, the three rulings appeared for a time to arrive finally at a coherent definition of software patentability—namely, that although algorithms by themselves are abstract concepts and therefore unpatentable, software programs may be patented if they employ algorithms to produce a tangible and inventive or transformative result. This view was further augmented by a 1998 U.S. Court of Appeals for the Federal Circuit decision in State Street Bank v. Signature Financial Group , which extended software patentability to software-enabled methods of doing business so long as these produced a “useful, concrete, and tangible result.” But this definitional equilibrium was not to last. The “useful, concrete, and tangible result” test in State Street Bank was rejected ten years later by the same court in In re Bilski , which upheld the USPTO’s denial of a patent for a method of hedging risk in commodities trading. The court instead offered a “machine or transformation” test, which allows a software program or business method to be patented only if it is implemented on a specific machine to achieve a special purpose that is novel, non-obvious, and useful; it transforms an article from one thing or state to another. But in its review of Bilski v. Kappos , the Supreme Court ruled that while the “machine or transformation” test was useful, it was not the only test for patentability. In addition to the “machine or transformation” test, the court decreed (rather vaguely) that any future test should be “grounded in the examples and concepts” expressed in its original “patent-eligibility trilogy” of opinions. They thus reaffirmed that business methods may indeed be patentable. Finally, a “Pretty Clear” Message While businesses and the courts were trying to figure out what the other tests for patentability might be, the Supreme Court provided further input with its March 2012 decision in Mayo Collaborative Services v. Prometheus Laboratories . Here, the court ruled that a process enabling physicians to correlate blood test results with medication levels to achieve the most appropriate dosages was ineligible for patent protection.” But then in June of 2014, The Supreme Court issued what may prove to be its most consequential decision on the patentability of software in the 33 years since Diamond v. Diehr . In Alice v. CLS Bank , the Court ruled that taking some activity that people have been doing for centuries—in this case, holding funds in escrow until a transaction is completed—and then merely “doing it through a computer” did not turn this age-old activity into a patentable new invention. At first, many observers believed that the effects of the Alice v. CLS Bank ruling would be very limited. Only the patent in the suit was invalidated, after all, not all software patents. What’s more, the abstract reasoning of the court in its decision did not provide clarity on how the ruling may or may not apply to other kinds of software patents—for example, the sort of software used in manufacturing that was ruled patentable in the 1981 Diamond v. Diehr case. But by October of 2014, a series of lower court decisions applying the new Alice v. CLS Bank standard had invalidated 13 additional software patents. As technology policy journalist Timothy B. Lee noted, “The courts are sending a pretty clear message: you can’t take a commonplace human activity, do it with a computer, and call that a patentable invention.” “ The courts are sending a pretty clear message: you can’t take a commonplace human activity, do it with a computer, and call that a patentable invention .” -Timothy B. Lee, technology policy journalist How far reaching will the impact of Alice v. CLS Bank be? “This doesn’t necessarily mean that all software patents are in danger,” Lee noted, because the patents involved “were particularly vulnerable to challenge under the new Alice precedent. But it does mean that the pendulum of patent law is clearly swinging in an anti-[software] patent direction.” Overcoming the Alice Paradox By late 2015, however, it was clear that the Alice ruling was having an impact not only on patent law, but also on the innovation process itself within corporate America. As John Cronin, a former top inventor at IBM and now the CEO of the innovation-on-demand firm ipCreate, observes: “The highest-value products and services today—the ones that increasingly drive margins in business—involve cloud computing, Big Data, machine learning, connectivity, mobility and location-based services, and on-demand and anything-as-a-service software applications and business processes. But ironically, these high-value innovations are also the most difficult to patent nowadays as a result of the Supreme Court’s Alice decision.” Cronin calls this the “ Alice Paradox,” and it has left many in-house patent groups struggling for a solution. One thing is clear: To be patentable nowadays, software has to take a genuinely-inventive step and either trigger an action, employ a device, or in some other way produce a tangible transformative result. In addition, smart companies are trying to address patentability issues involving software and business processes much earlier in the innovation cycle, before huge investments are made in R&D that may turn out to be not patentable. Overall, addressing the “ Alice Paradox” will be critical for many companies because patenting clearly adds value to a new product or service. In a groundbreaking joint study from Carnegie Mellon University, Georgia Institute of Technology, and Duke University entitled “R&D and the Patent Premium,” economists found that “the patent premium for innovations that were patented is substantial. Firms earn on average a 50% premium over the no patenting case, ranging from 60% in the health-related industries to 40% in electronics.” xlv xlv Ashish Arora, Marco Ceccagnoli, and Wesley M. Cohen, “ R&D and the Patent Premium ,” Science Direct, International Journal of Industrial Organization Issue 26, 2008. The Debate on Software Continues The debate over the dividing line between patentable versus unpatentable computer software-related inventions continues—in corporate R&D labs and in the courts. However, there are some who don’t believe that software and business methods should be patented under any conditions. They argue first of all that software is different from other industries—more iterative and more incremental, with each advance building upon thousands of previous advances. Therefore, their thinking goes, software should not be entitled to patents that ought to be more properly reserved for truly breakthrough or revolutionary inventions. There are two problems with this argument. First, as anyone in the semiconductor, chemical, or medical device industries can attest, innovation is no more iterative, incremental, or cumulative in software than is innovation in many other industries. Indeed, there are probably just as many or more patents for incremental semiconductor inventions that build modestly upon earlier work as there are patents for incremental software inventions that do the same. As patent scholar and veteran practitioner Paul Janicke of the University of Houston put it, “There really are no breakthrough inventions—at least not in the sense imagined by these critics. Everything moves one step at a time. In fact, every time I thought I encountered a large leap, it turned out that I didn’t know the full extent of the prior art.” The second problem with their logic is that the Founding Fathers specifically designed the patent system to encourage precisely this kind of incremental invention, so that ordinary people—using only the basic technical skills possessed by most citizens—could participate in rapidly developing the economy from the ground up. This was a very different approach than that of elitist European patent systems of the day, and it produced results that the rest of the world very soon came to envy (see “Section 1.5: What the U.S. Patent System Wrought”). As the October 21, 1876, issue of Scientific American noted, “In the aggregate the little things—which in England or the continent would not or could not be patented—probably add more to the wealth and wellbeing of the community … than the great things do.” Or to quote Thomas Jefferson himself: “A smaller [invention], applicable to our daily concerns, is infinitely more valuable than the greatest which can only be used for great objects.” xlvi Any uncertainty over the validity of incremental patenting was removed once and for all by the Patent Act of 1952. Consistent with the Founders’ intentions, U.S. law now explicitly holds that patent eligibility is not restricted solely to revolutionary inventions or “flash of genius” discoveries, but also includes more iterative advances in the state of the technological art so long as these meet the requisite novelty, non-obviousness, and utility criteria. xlvi From Jefferson’s letter to George Fleming in 1815, excerpt from The Jefferson Cyclopedia , courtesy of B. Zorina Khan. Evidence Shows Software Patents Don’t Hinder Innovation Another argument made by critics of software patenting is that patents stifle innovation and foster monopolization in the software industry. Research, however, suggests that this is decidedly not the case. xlvii If anything, in fact, the software industry has become even more innovative, more diversified, and more start-up friendly since patenting became common in the 1990s. You need only look at the huge proliferation of highly innovative start-ups in today’s social media and apps software fields to see just how erroneous the claim is that software patents stifle innovation. Or consider for a moment the fate of the Blackberry, once dominant but within the space of a couple of years superseded by more innovative competing smartphone makers. xlvii Robert Merges, “ Patents, Entry and Growth in The Software Industry ,” University of California at Berkeley School of Law, Berkeley, California, 2006. Retrieved from: http://papers.ssrn.com/sol3/papers.cfm?abstract_id=926204 Finally, some critics insist that the intangible nature of software ought to disqualify it from patentability. But as noted earlier, the Supreme Court has affirmed repeatedly that although abstract concepts cannot be patented, software that employs algorithms to produce a tangible and inventive result—e.g., software that governs the molding of raw synthetic rubber into cured precision products—may be patented. It’s also helpful to view this issue in a larger context. Forty years ago, 80 percent of the market value of all public companies resided in their tangible physical assets—their plant, equipment, and raw materials. In today’s Knowledge Economy, however, it is intangible assets—intellectual property—that make up 80 percent of the market value of public companies. xlviii xlviii Op. cit., Ocean Tomo. Indeed, the entire history of economic progress on our planet may be described as one long climb by humanity up the ladder of abstraction—from brute force to the subtle use of energy, from wealth derived from tangible resources and industrial machinery to wealth derived from ever-more ingenious ways to deploy that energy and those resources. It seems only logical, therefore, to expect that invention itself should follow a similar trajectory—from the realm of the tangible to the realm of the intangible. Ironically, the debate over patents for software, business methods, and other intangible inventions is nowhere more heated than on the Internet, itself an intangible realm in which “virtual” businesses launched with little more than hope and electrons (e.g., Facebook) are creating real and substantial wealth in the form of new products, new services, new jobs, and new economic growth for society. Yet strangely, those who have no trouble accepting the Internet as the intangible fruit of information age invention seem to get stuck in industrial age conceptions of what should and should not be patentable. Odd perhaps, but not surprising. The expansion of patentable subject matter into new and more intangible realms has always met with resistance. Patents involving the use of electricity were condemned 140 years ago, as were biotechnology patents 30 years ago, and of course software patents when they began to appear in large numbers 20 years ago. In each case, critics warned that these new kinds of patents would hold back further scientific discovery and innovation. Yet in each case, innovation and discovery actually intensified and their benefits to society multiplied. When Gene-Related Inventions Are Patentable A similar resistance is also developing toward gene-related patents. These began to be issued in significant numbers after the Supreme Court’s 1980 ruling in Diamond v. Chakrabarty , which upheld the first patent on a newly-created living organism—a bacterium for digesting crude oil in oil spills. Since then, patents have been granted for isolated gene sequences, but so far only on those with known functions and not on naturally- occurring genes in humans or other organisms. Patents have also been granted for gene sequences used in diagnostic testing, and on gene sequences that have been altered to make them more useful in a specific application. In March of 2010, however, a federal district court judge ruled in the case of Myriad Genetics that even isolated DNA is fundamentally the same as naturally- occurring DNA and is therefore ineligible for patenting. His ruling was reversed by the U.S. Court of Appeals for the Federal Circuit in July, 2011. But the Supreme Court then set aside that decision and directed the appeals court to once again review the case in light of its March, 2012 Prometheus decision. On August 16, 2012, however, the U.S. Court of Appeals for the Federal Circuit once again reaffirmed Myriad’s right to patent the isolated genes BCRA1 and BCRA2, which are involved in most inherited forms of breast and ovarian cancer. On June 13, 2013, however, the U.S. Supreme Court finally determined in a unanimous decision that a naturally occurring DNA segment is a product of nature and cannot be patented merely because it has been isolated, thereby invalidating Myriad’s patents on the BRCA1 and BRCA2 genes. The Court did rule, however, that the manipulation of a gene to create something not found in nature—such as a strand of synthetically-produced complementary DNA (cDNA)—could still be eligible for patent protection. To the average citizen—and perhaps to many patent lawyers as well—all this legal hairsplitting over the limits of patentability in the computer age must seem a bit like the debates in medieval times over how many angels can dance on the head of a pin. But two critical points must be borne in mind regarding these debates. First, no matter what anyone thinks the limits of patentability in an ideal world ought to be, out in the real world where we actually live, software, business method, and gene patents are multi- billion-dollar facts of life that businesses ignore only at their peril. Second, whatever confusion may exist today, the debates over patentability in the computer age will almost certainly be resolved eventually to most people’s satisfaction, just as all previous debates over patentability have. For if nothing else, the two hundred year-plus history of the courts and the patent office demonstrate a remarkable ability on the part of these institutions to adapt to the challenges posed by new technologies and new economic conditions. 1.7 Criteria for Patenting Learning Objectives After completing this section, you will be able to Identify the criteria that an invention must meet to earn a patent. Understand why non-obviousness is the most difficult hurdle to overcome. Can I Patent That? Before reading this section, please watch this overview video covering what you can and cannot patent. You can’t patent an idea (like an idea for a better mousetrap), only an application of that idea in a practical invention. Novelty, utility, and non-obviousness—the holy trinity of patents. Now that you’ve learned what can be patented and what cannot, we will next examine the criteria for determining if a patent-eligible invention actually merits one. These criteria center around three concepts mentioned in the previous section and enumerated in the Patent Act: novelty, utility, and non- obviousness. xlix xlix 35 U.S.C.§101, §102, and §103 Let’s discuss these three concepts in greater detail. Novelty The requirement in Sections 101 and 102 of the Patent Act for novelty in an invention means that to qualify for a patent, a machine, manufacture, process, or composition of matter must not have been previously described or known. Specifically, it must not have been patented, described in an unpublished or published patent application, explained in a printed publication such as an article or technical paper, or publicly known prior to the filing date of the new patent application. In addition, it must not have been published, used in public, or offered for sale by the applicant or their colleagues more than 12 months prior to the filing of a patent application. If any of the above is true of an invention, it is said to have been “anticipated” and cannot be patented. These novelty requirements exist whether the “prior art”—the catchall term for any previous patent, publication, or use—is domestic or foreign. This does not mean, of course, that your faster-than-light warp drive is unpatentable simply because it was envisioned in a general way in episodes of Star Trek and its successors’ television shows, and in many Star Trek books. “It is not enough that an invention be suggested by the literature,” explains the eminent New York University scholar Arthur R. Miller and his coauthor Michael H. Davis’ in their textbook for law students. l “Nor is it sufficient that the literature made the invention inevitable—that bears on the question of non-obviousness. The test, with one major exception, is whether enough of the invention has been disclosed to enable a person skilled in the applicable art to duplicate the product or process.” l Op. cit., Miller & Davis. That one exception, writes Miller and Davis, is public use of the invention. In that case, even a limited disclosure that does not reveal the secrets of the invention can still foreclose a patent if the public use of it “discloses the invention’s benefits.” Prior Art Must Be Enabling In the era of social media, the previously mentioned requirements could pose a novelty barrier if not handled properly. For instance, if you develop a new watch that displays information from an iPhone, and then disclose it on the crowdsourced funding site Kickstarter in order to raise capital from thousands of small-time investors, then you will probably want to file a patent application prior to, or certainly no later than a year after, your disclosure of the benefits of your watch to the public. But in the absence of such public use, disclosure in prior art must be substantial and enabling to be disqualifying. As patent attorney and writer of the widely read IP Watchdog blog Gene Quinn explains: “What Star Trek teaches is the idea of warp speed wit some suggested articulation of how it could be achieved. But that’s not informing enough. Someone could not make and use the device based on what is taught in Star Trek . So if you actually figure out how to make a faster-than-light warp drive work—and can describe it sufficiently so that someone skilled in the science of space propulsion could build it—then yes, it would be patentable.” Take heart, Star Trek fans! Utility As the Star Trek example suggests, the novelty issue can also touch on the question of utility—the second patentability criteria. Utility has a special meaning in patent law, which is simply that an invention must function and be of some benefit qualitatively—although no minimum quantum of benefit is necessary. The landscape of business is littered with companies that have invented not very useful or necessary products. But these may satisfy the requirement for utility if at least someone would find them useful. But snake oil medicines and other products that do not work in any meaningful way will not meet the requirement for utility. “The inventor of an ineffective drug may not obtain a patent merely because he convinces gullible patients that it has a non-existent curative effect,” Miller and Davis note. “It is not so much that it lacks a minimum quantum of benefit (the patients may find it subjectively useful), but it is, instead, that it has an impermissible fraudulent quality.” Even when no fraud is intended, the utility of a product or process must be demonstrate in a patent application—not presumed, but affirmatively demonstrated. Simply put, the thing or the method you have invented must actually work as it is intended and claimed to work. “Forget Star Trek for a moment,” says Quinn. “On a more mundane level, the USPTO used to deny patents for methods and compositions for re-growing hair. These were seen as lacking utility because re-growing hair was believed to be impossible. Finally, someone was able to prove that his method and composition actually re-grew hair on a bald scalp. The patent examiners withdrew their rejection, and patents for such products have issued ever since.” Interestingly, Quinn explains, since the earlier patent applications on hair-growing products didn’t describe anything that actually worked, they could not be used under the novelty bar to block later patent applications for hair-growing products that did work. Non-Obviousness An invention may be new. It may also have utility. But to meet the criteria for a patent, it must also be non-obvious under Section 103 of the Patent Act. Let’s now dig deeper into the requirements of the concept of non-obviousness. Requirements The requirement for non-obviousness may be illustrated with a fanciful example. If the number 4 were an invented product rather than a mathematical symbol, then even though the number 4 had never been invented before and was thus novel, it would still not be patentable. That’s because someone skilled in the art could have put 2 and 2 together to come up with it. But to offer a more practical example, say you invent a wheeled cart to move office supplies more easily between departments. If this is the first such wheeled office cart in history, you can get a patent for it. But if you then decide, “Hey, why not put those wheels on a chair?” you won’t get a patent for it. That’s because combining two such widely-known and available elements would be obvious to anyone skilled in the art of office furniture design. But things are not so obvious when it comes to inventing a camera phone. Even though it’s composed of well-known and widely-available components, combining the two did satisfy the requirement for non-obviousness because it became more than the sum of its parts and met a large and previously-unfilled need in the marketplace. The millions of people who take selfies everyday is certainly proof of that. There are various ways of presenting evidence that your invention satisfies the non-obvious requirement for patentability. You can demonstrate that the existing elements of your invention, although individually already known, yield an unexpected or hidden result. Or you can show that your invention, although composed of well- known and widely available components, when combined satisfies a long-felt but previously unfilled need in the marketplace, thus indicating its non-obviousness. Both of these demonstrations of non-obviousness apply to the camera phone example above. The One-Click Patent Some people criticized the so-called “one-click” patent granted by the USPTO to Amazon.com in 1999 for Amazon’s system enabling customers to buy an item with a single click of the mouse—with the payment information needed to complete the purchase already having been entered by the user previously. They contended that although Amazon might have been the first company to employ the process, it was an obvious and inevitable iteration of already- existing mouse-clicking procedures for making a purchase online. The patent office reexamined the patent, however, and in 2007 upheld the validity and the bulk of its major claims. It is important to note that it’s an invention’s function that is often examined to determine obviousness. “Even though it may be obvious that a certain object can be constructed in a certain way, its utility and novelty may lie in its functional use, not its construction,” write Miller and Davis. “Therefore, the prior art must be used to determine whether the invention’s new and useful function, not its construction, is non-obvious.” During the first half of the twentieth century, the courts often saw an invention as obvious when it lacked a “flash of genius” and was merely an incremental advance over the state of the art as opposed to what they imagined would be a “revolutionary” breakthrough discovery. But that subjective interpretation of inventiveness was overturned by the 1952 Patent Act, which codified a more objective standard—namely, that whether an invention is developed through laborious trial and error or through a eureka flash-of-genius moment has no bearing on its obviousness or non-obviousness. Overcoming Patent Hurdles Taken together, the three patenting criteria—novelty, utility, and non-obviousness—function like the obstacles in an Olympic hurdles race. The utility hurdle is easiest to overcome. The novelty hurdle less so. But by far, the highest hurdle facing inventors is non-obviousness. “The vast majority of all rejections at the patent office are for obviousness reasons,” explains retired Chief Judge Paul Michel of the U.S. Court of Appeals for the Federal Circuit, the main court that handles patent appeals. “And it’s not very difficult to see why. Given the millions of patented inventions over the decades, the tens of millions of past and current products on the market, it’s not all that easy to come up with an invention that is not only novel but also truly non-obvious to someone with ordinary skill in the state of the art.” Many believe that the criteria for patenting weakened in the late 1990s and early 2000s, and that as a result, too many poor-quality patents were issued. To the extent this problem exists, one of its likeliest causes is the fivefold increase in patent applications that has taken place over the last 30 years without a commensurate increase in USPTO funding, resources, and capabilities. Despite these challenges, the USPTO has made substantial progress in the last five years in improving examiner training and tools, reducing the backlog of pending applications, and strengthening the quality of the examination process for patent applications. This progress has been made despite oftentimes-unclear or contradictory patentability rulings from the courts. Patent quality is essential to the maintenance of public confidence in the patent system. After all, when property rights (either real or intellectual) are seen as overbroad, ill-defined, or illegitimate, individuals and businesses are more willing to trespass on them. 1.8 Other Types of Patents Learning Objectives After completing this section, you will be able to Explain the diff ences among utility, plant, and design patents. Describe common patent misconceptions. Up to this point, we have focused only on the most common types of patents, called utility patents , which preclude others from making, using, or selling the invention during the term of the patent, which begins on the grant date and ends 20 years from the filing date (for an average of 17 to 18 years). But in addition to these, the Patent Act also provides for two other types of patents— plant patents and design patents . Plant Patents Plant patents were first created by the Patent Act of 1930 , which had been proposed by Luther Burbank to protect new species of asexually reproduced plants, mostly flowers. These are different than the utility patents granted to bioengineered plants used in agriculture. The United States was the first country in the world to grant plant patents, and even today many countries continue to deny protection for plants. Indeed, even some signatories to the Agreement on Trade-Related Aspects of Intellectual Property Rights (TRIPS) administered by the World Trade Organization (WTO) reserve the right to deny patents for plants. Although the requirements for plant and design patents are substantially the same as those for utility patents, there are some crucial differences. The most important of these is the substitution of a different test for one of the three criteria for patentability discussed in the previous section. Instead of novelty, utility, and non-obviousness, the criteria for plant patentability are novelty, distinctiveness , and non-obviousness. To be patentable, plants must be cultivated rather than found in the wild, and plant patents are granted only to protect a new, distinct, and non-obvious variety of asexually reproduced plant—i.e., those grown not with seeds but by grafting, budding, or cutting. A plant need not be useful to qualify for a patent, but it must be distinctive in its color, habit, soil, flavor, productivity, form, or other aspects. Design Patents Design patents are granted to protect new, original, and non-obvious ornamental designs for articles of manufacture. Examples include Apple’s 2009 and 2010 patents— No. D593087 and No. D618677 —which covered among other things the unique, rounded-corner design of the iPhone, as well as its 2005 design patent No. D504889 for the look and feel of the iPad. Design patents can be just as valuable as utility patents, as Apple discovered when a jury awarded it $1 billion in damages against Samsung in August 2012, for the latter’s infringement of Apple’s utility and design patents. The case is currently on appeal. Like plant patents, design patents also substitute a different test than utility in their requirements for patentability. Instead of the novelty, utility, and non-obvious requirements for utility patents, the criteria for design patents are novelty, ornamentality , and non-obviousness. It was on the subject of design patents that one example of media confusion appeared. The New York Times published an article November 16, 2012, declaring in a sensational headline that “ Apple Now Owns the Page Turn .” The article claimed that a new Apple design patent “gives Apple the exclusive rights to the page turn in an e-reader application.” According to the article’s author, this showed “just how broken the patent system is.” Had the author of the article even read an obvious and easily-available source as the Wikipedia entry on design patents, however, he would have learned that design patents are granted only for nonfunctional ornamental designs. In fact, says Wikipedia, “design patents can be invalidated if the design has practical utility.” What Apple actually “owns,” therefore, is not the “page turn” function itself but merely the particular ornamental design of the way a page turn is executed in their devices. Another example of confused media reporting on patent matters was the February 6, 2013, Forbes article headlined: “ Is the Patent System Broken? Well, Amazon’s Just Patented the Sale of Second Hand Goods .” Amazon actually did no such thing, but the author of that article probably made this assumption after reading the abstract of the patent describing its general subject matter. Like many reporters new to patent issues, the author didn’t realize that the abstract tells you literally nothing about the exclusive rights conferred by a patent. Only the claims of the patent detail the specific exclusionary rights of the patent holder. Indeed, when you read the claims of the Amazon patent in question, you discover that Amazon hasn’t claimed ownership of the idea of a “market in second-hand digital goods” at all. Instead, the claims involve merely a very specific and novel method of conducting such a market. Meanwhile, Apple, ReDigi, and other firms have patented their own alternative methods of conducting a secondary digital market. 1.9 The Patenting Process Learning Objectives After completing this section, you will be able to Describe the steps in the patent application process. Discuss the importance of proper claims drafting. Applying for a Patent Much is at stake in the process of applying for a patent. Depending upon how you draft the claims and write the specification of your application, you could win or lose patent rights at any point in the examination process. In addition, any patent rights you win can be worth a considerable amount of money, and can be enforced by the U.S. federal courts. An applicant must first determine whether to file an application for a utility, design, or plant patent. Then, the applicant must determine their filing status: large entity, small entity, or the new category of micro entity created by the America Invents Act of 2011 (AIA) . Small entities, which are universities, non-profits, and small businesses with fewer than 500 employees who also meet certain other criteria, receive a 50 percent discount on the application fees paid by large entities. Micro entities, which are small entities who have a gross income less than three times U.S. median household income or meet certain other criteria, receive a 75 percent discount. These discounts on USPTO fees for small and micro entities do not apply to the attorneys’ fees often involved in applying for a patent, which can be significant. Provisional vs. Nonprovisional Patent Application Finally, the applicant must decide whether to file an abbreviated, “provisional” patent application or a complete, “nonprovisional” one. A provisional application consists only of the specification describing the invention for which a patent is sought, as well as any drawings that might be necessary to understand the invention. A provisional application is not subject to examination, and is viable for one year. The chief benefits of a provisional application are twofold. It is much less expensive to file than a regular nonprovisional application—only $1,000 in official fees for large entities, $500 for small entities, and $250 for micro entities. It also gives the inventor the benefit of the earlier provisional filing date of the nonprovisional application based on the same specification, while measuring the term of the patent from the nonprovisional application’s filing date. In a sense, the provisional application serves as a placeholder for up to one year while the inventor does all the prior art searching, claims drafting, and other work required of a full and complete nonprovisional application. This priority date placeholder function can be important given that many companies and inventors are working on new products and services aimed at the same markets. This is especially so under the United States’ new “first inventor to file” rather than “first to invent” priority regime, which some fear may give an edge to large companies with the legal and financial resources to file early and often. To the extent this concern may be valid, provisional applications can serve to mitigate any large company filing advantage. The main disadvantage of a provisional application is that because the written description cannot be changed when filing the follow-on, nonprovisional application, all the subsequent claims in that follow-on application must be completely consistent with the earlier description language. As most inventors can attest, the understanding of an invention and its potential market—as well as the claims best suited to protect it—inevitably evolves and matures over time. Here’s how an experienced entrepreneur describes the value of a provisional application in the “first inventor to file” environment: “What I recommend to every entrepreneur is that if you write a new, non-obvious, and useful line of code, put it in the specification of a provisional patent application and file it. It only costs $1,000 at most. You then have a year in which to honestly evaluate where the industry is going, where the market is going, and whether your invention is truly valuable enough to pursue a patent for it.” A year might not seem very long. But a lot can happen to markets and to technology in that amount of time. Thanks to the rapid rise of smartphones, for example, it took merely a year for netbooks to go from the “next big thing” to “who cares?” The Critical Importance of the Claims When it comes to filing a full nonprovisional application, the most critical task of the inventor (and patent attorney) is to draft the claims. This is an art in and of itself, one that will determine the inventor’s rights and an infringer’s liability. Each claim serves as a stand-alone definition of the patent coverage—as a sort of mini-patent unto itself. After a patent is granted, a claim is the only thing that someone can be accused of infringing. Accordingly, broad claim language is essential if a commercially meaningful patent is to be obtained. On the other hand, the broader the claim, the more likely it is that prior art may exist somewhere that anticipates the claim or renders it obvious and, therefore, invalidates the claim. So the competent draftsperson submits a dozen or more claims, typically moving from broader to narrower scope, in case the broader claims turn out to be disallowed by the USPTO or later invalidated by a court. Some applicants make the opposite mistake and draft claims that are too narrow—“a programmable multifunction computer in the shape of a metal clamshell,” for example. Such a claim is of little value because others can easily design around it simply by using plastic or other nonmetal materials in the design. Some claims are so narrow they are even referred to as “picture claims” because they paint a literal and limiting picture of the invention. You may get a patent with such picture claims, but it probably won’t be worth the paper it’s printed on. The strongest claims usually define powerful functionality. They capture something fundamental or seminal in the functioning of the invention. A good example is the claims in the aforementioned Amazon one-click patent. The algorithms for “one-click” shopping are not very complicated. Yet the claims capture a very profound functionality—the idea that a user should not have to type in credit card and shipping information every time he or she wants to buy something. The consumer-friendly functionality captured in that patent’s claims has won Amazon a lot of customers and made it a lot of money. Reviewing the Patent Application Once the patent application with all necessary forms is filed and all fees are paid, the patent examiner will review the patent application to determine if the invention meets the statutory requirements for patentability. The examiner will also conduct a search of patent and other databases to determine if the invention appears to be truly novel and non-obvious. Once a determination has been made, the patent examiner will send the applicant a document known as a first office action , in which the patent examiner approves, rejects, or requires additional information about the claims and/or other elements of the application. If all the claims are allowed, which is rare in a first office action, the patent prosecution process is complete. A more common next step requires the applicant to respond to the patent examiner’s rejections and requests for more information. In this response, the applicant will address all of the examiner’s concerns and either rebut them or amend the application, typically by revising some or all of the claims. But according to the Manual of Patenting Examination Procedure (MPEP) Section 1.121, “No amendment may introduce new matter into the disclosure of an application.” li Thus, an applicant cannot file an application disclosing a new compound and how to make it, and then later, after discovering that the compound’s structure and method are incorrect, amend the description. li United States Patent and Trademark Office. (2010, July 21). Manual of Patent Examining Procedure § 1.121. Retrieved from http://www.uspto.gov/web/offices/pac/mpep/documents/appxr_1_121.htm After responding to the office action by perhaps amending the application, the examination process continues until the patent examiner either allows all of the claims or finally rejects them. If all claims are allowed, then the patent prosecution process is complete. If some claims are finally rejected, then the applicant’s options at this point are more limited. According to MPEP Section 706.07, “In the second or any subsequent examination or consideration by the examiner, the rejection can be made final.” lii At that point, the applicant must usually choose one of three approaches: Cancel the rejected claims, leaving only allowed claims to issue as a patent; continue the fight by filing what is called a “continuation application” and drafting new claims; or appeal to the Patent Trial and Appeals Board arguing that the patent examiner erred in not allowing the claims. liii Any appeal to the Patent Trial and Appeals Board, as with any other office action, must occur within six months. liv lii United States Patent and Trademark Office. (2010, July 21). Manual of Patent Examining Procedure §.0 Retrieved from http://www.uspto.gov/web/offices/pac/mpep/documents/0700_706_07.htm#sect706.07 liii 37 CFR Part 41. Department of Commerce, United States Patent and Trademark Office. (2008). Rules of practice before the board of patent appeals and interferences in ex parte appeals . Retrieved from website: http://www.gpo.gov/fdsys/pkg/FR-2008-06-10/pdf/E8-12451.pdf liv 37 CFR § 1.134 Finally, if the patent has been vetted through the patent prosecution process and is ready for issuance, the patent holder must pay the applicable fee. If the applicant pays the issue fee, the USPTO will issue the patent in due course. Additionally, utility patents are subject to maintenance fees. These fees are due 3 years and 6 months, 7 years and 6 months, and 11 years and 6 months from the date of the original patent grant. Plant and design patents are also required to pay maintenance fees. lv lv 37 CFR § 1.362
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Summary 17.1 Defining Foreign Policy As the president, Congress, and others carry out U.S. foreign policy in the areas of trade, diplomacy, defense, intelligence, foreign aid, and global environmental policy, they pursue a variety of objectives and face a multitude of challenges. The four main objectives of U.S. foreign policy are the protection of the United States and its citizens and allies, the assurance of continuing access to international resources and markets, the preservation of a balance of power in the world, and the protection of human rights and democracy. The challenges of the massive and complex enterprise of U.S. foreign policy are many. First, there exists no true world-level authority dictating how the nations of the world should relate to one another. A second challenge is the widely differing views among countries about the role of government in people’s lives. A third is other countries’ varying ideas about the appropriate form of government. A fourth challenge is that many new foreign policy issues transcend borders. Finally, the varying conditions of the countries in the world affect what is possible in foreign policy and diplomatic relations. 17.2 Foreign Policy Instruments U.S. foreign policy outputs vary considerably. At one end of the continuum are sharply focused outputs such as the presidential use of military force via a specific drone strike on an enemy target, or the forging of a presidential summit with another country’s president or head of state. At the other end of the spectrum are broadly focused outputs that typically bring more involvement from the Congress and other world leaders, such as the process to formalize a multilateral treaty on the global environment or the process to finalize the U.S. diplomatic budget each fiscal year. Broadly focused outputs typically take more time to decide, involve more nation-states, are more expensive, and are quite difficult to reverse once in place. Sharply focused outputs are faster, tend to be led by the president, and are easier for future policymakers to undo. 17.3 Institutional Relations in Foreign Policy Many aspects of foreign policymaking rely on the powers shared between Congress and the president, including foreign policy appointments and the foreign affairs budget. Within the executive branch, an array of foreign policy leaders report directly to the president. Foreign policy can at times seem fragmented and diffuse because of the complexity of actors and topics. However, the president is clearly the leader, having both formal authority and the ability to delegate to Congress, as explained in the two presidencies thesis. With this leadership, presidents at times can make foreign policymaking quick and decisive, especially when it calls for executive agreements and the military use of force. 17.4 Approaches to Foreign Policy Classic theories of foreign policy divide into the isolationist camp and the internationalist camp. The use of hard versus soft power comes into play in the internationalist route. Neoconservatism, a more recent school of thought in foreign policy, takes the view that the United States should go it alone as a single superpower, retreating from foreign involvement with the exception of trade and economic policy. In the end, the complexity of international relationships, combined with a multifaceted decision-making process and a multiplicity of actors, leads to a U.S. foreign policy approach that uses a bit of all the schools of thought. The United States is being neoconservative when drone strikes are carried out unilaterally within the boundaries of another sovereign nation. It is being internationalist when building a coalition on the Iran nuclear deal or when participating in NATO initiatives.
Chapter Outline 17.1 Defining Foreign Policy 17.2 Foreign Policy Instruments 17.3 Institutional Relations in Foreign Policy 17.4 Approaches to Foreign Policy Introduction The U.S. government interacts with a large number of international actors, from other governments to private organizations, to fight global problems like terrorism and human trafficking, and to meet many other national foreign policy goals such as encouraging trade and protecting the environment. Sometimes these goals are conflicting. Perhaps because of these realities, the president is in many ways the leader of the foreign policy domain. When the United States wishes to discuss important issues with other nations, the president (or a representative such as the secretary of state) typically does the talking, as when President Barack Obama visited with Russian president Vladimir Putin in 2013 ( Figure 17.1 ). But don’t let this image mislead you. While the president is the country’s foreign policy leader, Congress also has many foreign policy responsibilities, including approving treaties and agreements, allocating funding, making war, and confirming ambassadors. These and various other activities constitute the patchwork quilt that is U.S. foreign policy. How are foreign and domestic policymaking different, and how are they linked? What are the main foreign policy goals of the United States? How do the president and Congress interact in the foreign policy realm? In what different ways might foreign policy be pursued? This chapter will delve into these and other issues to present an overview U.S. foreign policy.
[ { "answer": { "ans_choice": 3, "ans_text": "bureaucratic oversight" }, "bloom": null, "hl_context": "Besides participating in the UN and NATO , the United States also distributes hundreds of millions of dollars each year in foreign aid to improve the quality of life of citizens in developing countries . The United States may also forgive the foreign debts of these countries . By definition , developing countries are not modernized in terms of infrastructure and social services and thus suffer from instability . Helping them modernize and develop stable governments is intended as a benefit to them and a prop to the stability of the world . An alternative view of U . S . assistance is that there are more nefarious goals at work , that perhaps it is intended to buy influence in developing countries , secure a position in the region , obtain access to resources , or foster dependence on the United States . <hl> The United States pursues its four main foreign policy goals through several different foreign policy types , or distinct substantive areas of foreign policy in which the United States is engaged . <hl> <hl> These types are trade , diplomacy , sanctions , military / defense , intelligence , foreign aid , and global environmental policy . <hl>", "hl_sentences": "The United States pursues its four main foreign policy goals through several different foreign policy types , or distinct substantive areas of foreign policy in which the United States is engaged . These types are trade , diplomacy , sanctions , military / defense , intelligence , foreign aid , and global environmental policy .", "question": { "cloze_format": "(The) ___ is not a foreign policy type.", "normal_format": "Which of the following is not a foreign policy type?", "question_choices": [ "trade policy", "intelligence policy", "war-making", "bureaucratic oversight" ], "question_id": "fs-id1172504370596", "question_text": "Which of the following is not a foreign policy type?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 3, "ans_text": "D" }, "bloom": null, "hl_context": "What are the objectives of U . S . foreign policy ? <hl> While the goals of a nation ’ s foreign policy are always open to debate and revision , there are nonetheless four main goals to which we can attribute much of what the U . S . government does in the foreign policy realm : ( 1 ) the protection of the U . S . and its citizens , ( 2 ) the maintenance of access to key resources and markets , ( 3 ) the preservation of a balance of power in the world , and ( 4 ) the protection of human rights and democracy . <hl>", "hl_sentences": "While the goals of a nation ’ s foreign policy are always open to debate and revision , there are nonetheless four main goals to which we can attribute much of what the U . S . government does in the foreign policy realm : ( 1 ) the protection of the U . S . and its citizens , ( 2 ) the maintenance of access to key resources and markets , ( 3 ) the preservation of a balance of power in the world , and ( 4 ) the protection of human rights and democracy .", "question": { "cloze_format": "The goals of U.S. foreign policy include ________.", "normal_format": "What do the goals of U.S. foreign policy include?", "question_choices": [ "keeping the country safe", "securing access to foreign markets", "protecting human rights", "all the above" ], "question_id": "fs-id1172504319271", "question_text": "The goals of U.S. foreign policy include ________." }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 3, "ans_text": "international agreements" }, "bloom": null, "hl_context": "<hl> The final example of a focused foreign policy input is the passage of an emergency funding measure for a specific national security task . <hl> Congress tends to pass at least one emergency spending measure per year , which must be signed by the president to take effect , and it often provides funding for domestic disasters . However , at times foreign policy matters drive an emergency spending measure , as was the case right after the 9/11 attacks . In such a case , the president or the administration proposes particular amounts for emergency foreign policy plans . 17.3 Institutional Relations in Foreign Policy In addition to the broad-based foreign policy outputs above , which are president-led with some involvement from Congress , many other decisions need to be made . <hl> These sharply focused foreign policy outputs tend to be exclusively the province of the president , including the deployment of troops and / or intelligence agents in a crisis , executive summits between the president and other heads of state on targeted matters of foreign policy , presidential use of military force , and emergency funding measures to deal with foreign policy crises . <hl> These measures of foreign policy are more quickly enacted and demonstrate the “ energy and dispatch ” that Alexander Hamilton , writing in the Federalist Papers , saw as inherent in the institution of the presidency . Emergency spending does involve Congress through its power of the purse , but Congress tends to give presidents what they need to deal with emergencies . That said , the framers were consistent in wanting checks and balances sprinkled throughout the Constitution , including in the area of foreign policy and war powers . Hence , Congress has several roles , as discussed at points throughout this chapter . <hl> Broadly focused foreign policy outputs not only span multiple topics and organizations , but they also typically require large-scale spending and take longer to implement than sharply focused outputs . <hl> <hl> In the realm of broadly focused outputs , we will consider public laws , the periodic reauthorization of the foreign policy agencies , the foreign policy budget , international agreements , and the appointment process for new executive officials and ambassadors . <hl>", "hl_sentences": "The final example of a focused foreign policy input is the passage of an emergency funding measure for a specific national security task . These sharply focused foreign policy outputs tend to be exclusively the province of the president , including the deployment of troops and / or intelligence agents in a crisis , executive summits between the president and other heads of state on targeted matters of foreign policy , presidential use of military force , and emergency funding measures to deal with foreign policy crises . Broadly focused foreign policy outputs not only span multiple topics and organizations , but they also typically require large-scale spending and take longer to implement than sharply focused outputs . In the realm of broadly focused outputs , we will consider public laws , the periodic reauthorization of the foreign policy agencies , the foreign policy budget , international agreements , and the appointment process for new executive officials and ambassadors .", "question": { "cloze_format": "All the following are examples of sharply focused foreign policy outputs except ________.", "normal_format": "Which the following is not an example of sharply focused foreign policy outputs?", "question_choices": [ "presidential summits", "military uses of force", "emergency spending measures", "international agreements" ], "question_id": "fs-id1172504441733", "question_text": "All the following are examples of sharply focused foreign policy outputs except ________." }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 1, "ans_text": "B" }, "bloom": null, "hl_context": "Its main feature was a requirement that presidents get approval from Congress to continue any military campaign beyond sixty days . <hl> To many , however , the overall effect was actually to strengthen the role of the president in war-making . <hl> After all , the law clarified that presidents could act on their own for sixty days before getting authorization from Congress to continue , and many smaller-scale conflicts are over within sixty days . Before the War Powers Resolution , the first approval for war was supposed to come from Congress . In theory , Congress , with its constitutional war powers , could act to reverse the actions of a president once the sixty days have passed . However , a clear disagreement between Congress and the president , especially once an initiative has begun and there is a “ rally around the flag ” effect , is relatively rare . More likely are tough questions about the campaign to which continuing congressional funding is tied . The War Powers Resolution was passed in 1973 by a congressional override of President Richard Nixon ’ s veto . The bill was Congress ’ s attempt to reassert itself in war-making . Congress has the power to declare war , but it had not formally done so since Japan ’ s 1941 attack on Pearl Harbor brought the United States into World War II . Yet the United States had entered several wars since that time , including in Korea , in Vietnam , and in focused military campaigns such as the failed 1961 Bay of Pigs invasion of Cuba . <hl> The War Powers Resolution created a new series of steps to be followed by presidents in waging military conflict with other countries . <hl>", "hl_sentences": "To many , however , the overall effect was actually to strengthen the role of the president in war-making . The War Powers Resolution created a new series of steps to be followed by presidents in waging military conflict with other countries .", "question": { "cloze_format": "The War Powers Resolution ________.", "normal_format": "Which of the following is correct about the War Powers Resolution?", "question_choices": [ "strengthened congressional war powers", "strengthened presidential war powers", "affected the presidency and congress equally", "ultimately had little impact on war-making" ], "question_id": "fs-id1172504435616", "question_text": "The War Powers Resolution ________." }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 2, "ans_text": "the budget for every presidential action has to be approved in advance" }, "bloom": null, "hl_context": "<hl> The federal budget process is an important annual tradition that affects all areas of foreign policy . <hl> <hl> The foreign policy and defense budgets are part of the discretionary budget , or the section of the national budget that Congress vets and decides on each year . <hl> <hl> Foreign policy leaders in the executive and legislative branches must advocate for funding from this budget , and while foreign policy budgets are usually renewed , there are enough proposed changes each year to make things interesting . <hl> <hl> In addition to new agencies , new cross-national projects are proposed each year to add to infrastructure and increase or improve foreign aid , intelligence , and national security technology . <hl>", "hl_sentences": "The federal budget process is an important annual tradition that affects all areas of foreign policy . The foreign policy and defense budgets are part of the discretionary budget , or the section of the national budget that Congress vets and decides on each year . Foreign policy leaders in the executive and legislative branches must advocate for funding from this budget , and while foreign policy budgets are usually renewed , there are enough proposed changes each year to make things interesting . In addition to new agencies , new cross-national projects are proposed each year to add to infrastructure and increase or improve foreign aid , intelligence , and national security technology .", "question": { "cloze_format": "The federal budget process matters in foreign policy for all the following reasons except ________.", "normal_format": "The federal budget process doesn't matter in foreign policy for which of the following reasons?", "question_choices": [ "Congress has the power of the purse, so the president needs its approval", "the budget provides the funding needed to run the foreign policy agencies", "the budget for every presidential action has to be approved in advance", "the budget allows political institutions to increase funding in key new areas" ], "question_id": "fs-id1172504347364", "question_text": "The federal budget process matters in foreign policy for all the following reasons except ________." }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 1, "ans_text": "the president and Congress share power" }, "bloom": null, "hl_context": "<hl> At bottom , the United States is a separation-of-powers political system with authority divided among executive and legislative branches , including in the foreign policy realm . <hl> Table 17.1 shows the formal roles of the president and Congress in conducting foreign policy . <hl> While presidents are more empowered by the Constitution in foreign than in domestic policy , they nonetheless must seek approval from Congress on a variety of matters ; chief among these is the basic budgetary authority needed to run foreign policy programs . <hl> <hl> Indeed , most if not all of the foreign policy instruments described earlier in this chapter require interbranch approval to go into effect . <hl> Such approval may sometimes be a formality , but it is still important . Even a sole executive agreement often requires subsequent funding from Congress in order to be carried out , and funding calls for majority support from the House and Senate . <hl> Presidents lead , to be sure , but they must consult with and engage the Congress on many matters of foreign policy . <hl> Presidents must also delegate a great deal in foreign policy to the bureaucratic experts in the foreign policy agencies . Not every operation can be run from the West Wing of the White House . <hl> FOREIGN POLICY AND SHARED POWER <hl>", "hl_sentences": "At bottom , the United States is a separation-of-powers political system with authority divided among executive and legislative branches , including in the foreign policy realm . While presidents are more empowered by the Constitution in foreign than in domestic policy , they nonetheless must seek approval from Congress on a variety of matters ; chief among these is the basic budgetary authority needed to run foreign policy programs . Indeed , most if not all of the foreign policy instruments described earlier in this chapter require interbranch approval to go into effect . Presidents lead , to be sure , but they must consult with and engage the Congress on many matters of foreign policy . FOREIGN POLICY AND SHARED POWER", "question": { "cloze_format": "In terms of formal powers in the realm of foreign policy, ________.", "normal_format": "Which of the following is true in terms of formal powers in the realm of foreign policy?", "question_choices": [ "the president is entirely in charge", "the president and Congress share power", "Congress is entirely in charge", "decisions are delegated to experts in the bureaucracy" ], "question_id": "fs-id1172504413867", "question_text": "In terms of formal powers in the realm of foreign policy, ________." }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 2, "ans_text": "C" }, "bloom": null, "hl_context": "While key White House , executive , and legislative leaders monitor and regularly weigh in on foreign policy matters , the fact is that individual representatives and senators do so much less often . <hl> Unless there is a foreign policy crisis , legislators in Congress tend to focus on domestic matters , mainly because there is not much to be gained with their constituents by pursuing foreign policy matters . <hl> <hl> 11 Domestic policy matters resonate more strongly with the voters at home . <hl> A sluggish economy , increasing health care costs , and crime matter more to them than U . S . policy toward North Korea , for example . In an open-ended Gallup poll question from early 2016 about the “ most important problem ” in the United States , fewer than 15 percent of respondents named a foreign policy topic ( half of those respondents mentioned immigration ) . These results suggest that foreign policy is not at the top of many voters ’ minds . In the end , legislators must be responsive to constituents in order to be good representatives and to achieve reelection . 12", "hl_sentences": "Unless there is a foreign policy crisis , legislators in Congress tend to focus on domestic matters , mainly because there is not much to be gained with their constituents by pursuing foreign policy matters . 11 Domestic policy matters resonate more strongly with the voters at home .", "question": { "cloze_format": "House members and senators tend to be less active on foreign policy matters than domestic ones because ___.", "normal_format": "Why do House members and senators tend to be less active on foreign policy matters than domestic ones?", "question_choices": [ "Foreign policy matters are more technical and difficult.", "Legislators do not want to offend certain immigrant groups within their constituency.", "Constituents are more directly affected by domestic policy topics than foreign ones.", "Legislators themselves are not interested in foreign policy matters." ], "question_id": "fs-id1172504379871", "question_text": "Why do House members and senators tend to be less active on foreign policy matters than domestic ones?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 2, "ans_text": "C" }, "bloom": null, "hl_context": "Two particular events in foreign policy caused many to change their views about the proper approach to U . S . involvement in world affairs . <hl> First , the debacle of U . S . involvement in the civil war in Vietnam in the years leading up to 1973 caused many to rethink the country ’ s traditional containment approach to the Cold War . <hl> <hl> Containment was the U . S . foreign policy goal of limiting the spread of communism . <hl> In Vietnam the United States supported one governing faction within the country ( democratic South Vietnam ) , whereas the Soviet Union supported the opposing governing faction ( communist North Vietnam ) . The U . S . military approach of battlefield engagement did not translate well to the jungles of Vietnam , where “ guerilla warfare ” predominated .", "hl_sentences": "First , the debacle of U . S . involvement in the civil war in Vietnam in the years leading up to 1973 caused many to rethink the country ’ s traditional containment approach to the Cold War . Containment was the U . S . foreign policy goal of limiting the spread of communism .", "question": { "cloze_format": "The U.S. policy of containment during the Cold War related to keeping ________.", "normal_format": "What was the U.S. policy of containment during the Cold War related to keeping?", "question_choices": [ "terrorism from spreading", "rogue countries like North Korea from developing nuclear weapons", "communism from spreading", "oil prices from rising" ], "question_id": "fs-id1172504354427", "question_text": "The U.S. policy of containment during the Cold War related to keeping ________." }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 1, "ans_text": "neoconservativism" }, "bloom": null, "hl_context": "Neoconservatives believe that rather than exercising restraint and always using international organizations as the path to international outcomes , the United States should aggressively use its might to promote its values and ideals around the world . The aggressive use ( or threat ) of hard power is the core value of neoconservatism . Acting unilaterally is acceptable in this view , as is adopting a preemptive strategy in which the United States intervenes militarily before the enemy can make its move . Preemption is a new idea ; the United States has tended to be retaliatory in its use of military force , as in the case of Pearl Harbor at the start of World War II . <hl> Examples of neoconservativism in action are the 1980s U . S . campaigns in Central American countries to turn back communism under President Ronald Reagan , the Iraq War of 2003 led by President George W . Bush and his vice president Dick Cheney ( Figure 17.17 ) , and the use of drones as counterterrorism weapons during the Obama administration . <hl>", "hl_sentences": "Examples of neoconservativism in action are the 1980s U . S . campaigns in Central American countries to turn back communism under President Ronald Reagan , the Iraq War of 2003 led by President George W . Bush and his vice president Dick Cheney ( Figure 17.17 ) , and the use of drones as counterterrorism weapons during the Obama administration .", "question": { "cloze_format": "The use of drones within other countries’ borders is consistent with the school of thought of ___ .", "normal_format": "The use of drones within other countries’ borders is consistent with which school of thought?", "question_choices": [ "liberal internationalism", "neoconservativism", "neo-isolationism", "grand strategy" ], "question_id": "fs-id1172504438330", "question_text": "The use of drones within other countries’ borders is consistent with which school of thought?" }, "references_are_paraphrase": null } ]
17
17.1 Defining Foreign Policy Learning Objectives By the end of this section, you will be able to: Explain what foreign policy is and how it differs from domestic policy Identify the objectives of U.S. foreign policy Describe the different types of foreign policy Identify the U.S. government’s main challenges in the foreign policy realm When we consider policy as our chapter focus, we are looking broadly at the actions the U.S. government carries out for particular purposes. In the case of foreign policy, that purpose is to manage its relationships with other nations of the world. Another distinction is that policy results from a course of action or a pattern of actions over time, rather than from a single action or decision. For example, U.S. foreign policy with Russia has been forged by several presidents, as well as by cabinet secretaries, House and Senate members, and foreign policy agency bureaucrats. Policy is also purposive, or intended to do something; that is, policymaking is not random. When the United States enters into an international agreement with other countries on aims such as free trade or nuclear disarmament, it does so for specific reasons. With that general definition of policy established, we shall now dig deeper into the specific domain of U.S. foreign policy. FOREIGN POLICY BASICS What is foreign policy ? We can think of it on several levels, as “the goals that a state’s officials seek to attain abroad, the values that give rise to those objectives, and the means or instruments used to pursue them.” 1 This definition highlights some of the key topics in U.S. foreign policy, such as national goals abroad and the manner in which the United States tries to achieve them. Note too that we distinguish foreign policy, which is externally focused, from domestic policy, which sets strategies internal to the United States, though the two types of policies can become quite intertwined. So, for example, one might talk about Latino politics as a domestic issue when considering educational policies designed to increase the number of Hispanic Americans who attend and graduate from a U.S. college or university. 2 However, as demonstrated in the primary debates leading up to the 2016 election, Latino politics can quickly become a foreign policy matter when considering topics such as immigration from and foreign trade with countries in Central America and South America ( Figure 17.2 ). 3 What are the objectives of U.S. foreign policy? While the goals of a nation’s foreign policy are always open to debate and revision, there are nonetheless four main goals to which we can attribute much of what the U.S. government does in the foreign policy realm: (1) the protection of the U.S. and its citizens, (2) the maintenance of access to key resources and markets, (3) the preservation of a balance of power in the world, and (4) the protection of human rights and democracy. The first goal is the protection of the United States and the lives of it citizens, both while they are in the United States and when they travel abroad. Related to this security goal is the aim of protecting the country’s allies, or countries with which the United States is friendly and mutually supportive. In the international sphere, threats and dangers can take several forms, including military threats from other nations or terrorist groups and economic threats from boycotts and high tariffs on trade. In an economic boycott, the United States ceases trade with another country unless or until it changes a policy to which the United States objects. Ceasing trade means U.S. goods cannot be sold in that country and its goods cannot be sold in the United States. For example, in recent years the United States and other countries implemented an economic boycott of Iran as it escalated the development of its nuclear energy program. The recent Iran nuclear deal is a pact in which Iran agrees to halt nuclear development while the United States and six other countries lift economic sanctions to again allow trade with Iran. Barriers to trade also include tariffs, or fees charged for moving goods from one country to another. Protectionist trade policies raise tariffs so that it becomes difficult for imported goods, now more expensive, to compete on price with domestic goods. Free trade agreements seek to reduce these trade barriers. The second main goal of U.S. foreign policy is to ensure the nation maintains access to key resources and markets across the world. Resources include natural resources, such as oil, and economic resources, including the infusion of foreign capital investment for U.S. domestic infrastructure projects like buildings, bridges, and weapons systems. Of course, access to the international marketplace also means access to goods that American consumers might want, such as Swiss chocolate and Australian wine. U.S. foreign policy also seeks to advance the interests of U.S. business, to both sell domestic products in the international marketplace and support general economic development around the globe (especially in developing countries). A third main goal is the preservation of a balance of power in the world. A balance of power means no one nation or region is much more powerful militarily than are the countries of the rest of the world. The achievement of a perfect balance of power is probably not possible, but general stability, or predictability in the operation of governments, strong institutions, and the absence of violence within and between nations may be. For much of U.S. history, leaders viewed world stability through the lens of Europe. If the European continent was stable, so too was the world. During the Cold War era that followed World War II, stability was achieved by the existence of dual superpowers, the United States and the Soviet Union, and by the real fear of the nuclear annihilation of which both were capable. Until approximately 1989–1990, advanced industrial democracies aligned themselves behind one of these two superpowers. Today, in the post–Cold War era, many parts of Europe are politically more free than they were during the years of the Soviet bloc, and there is less fear of nuclear war than when the United States and the Soviet Union had missiles pointed at each other for four straight decades. However, despite the mostly stabilizing presence of the European Union (EU), which now has twenty-eight member countries, several wars have been fought in Eastern Europe and the former Soviet Union. Moreover, the EU itself faces some challenges, including a vote in the United Kingdom to leave the EU, the ongoing controversy about how to resolve the national debt of Greece, and the crisis in Europe created by thousands of refugees from the Middle East. Carefully planned acts of terrorism in the United States, Asia, and Europe have introduced a new type of enemy into the balance of power equation—nonstate or nongovernmental organizations, such as al-Qaeda and ISIS (or ISIL), consisting of various terrorist cells located in many different countries and across all continents ( Figure 17.3 ). The fourth main goal of U.S. foreign policy is the protection of human rights and democracy. The payoff of stability that comes from other U.S. foreign policy goals is peace and tranquility. While certainly looking out for its own strategic interests in considering foreign policy strategy, the United States nonetheless attempts to support international peace through many aspects of its foreign policy, such as foreign aid, and through its support of and participation in international organizations such as the United Nations, the North Atlantic Treaty Organization (NATO), and the Organization of American States. The United Nations (UN) is perhaps the foremost international organization in the world today. The main institutional bodies of the UN are the General Assembly and the Security Council. The General Assembly includes all member nations and admits new members and approves the UN budget by a two-thirds majority. The Security Council includes fifteen countries, five of which are permanent members (including the United States) and ten that are nonpermanent and rotate on a five-year-term basis. The entire membership is bound by decisions of the Security Council, which makes all decisions related to international peace and security. Two other important units of the UN are the International Court of Justice in The Hague (Netherlands) and the UN Secretariat, which includes the Secretary-General of the UN and the UN staff directors and employees. Milestone The Creation of the United Nations One of the unique and challenging aspects of global affairs is the fact that no world-level authority exists to mandate when and how the world’s nations interact. After the failed attempt by President Woodrow Wilson and others to formalize a “ League of Nations ” in the wake of World War I in the 1920s, and on the heels of a worldwide depression that began in 1929, came World War II, history’s deadliest military conflict. Now, in the early decades of the twenty-first century, it is common to think of the September 11 terrorist attacks in 2001 as the big game-changer. Yet while 9/11 was hugely significant in the United States and abroad, World War II was even more so. The December 1941 Japanese attack on Pearl Harbor (Hawaii) was a comparable surprise-style attack that plunged the United States into war. The scope of the conflict, fought in Europe and the Pacific Ocean, and Hitler’s nearly successful attempt to take over Europe entirely, struck fear in minds and hearts. The war brought about a sea change in international relations and governance, from the Marshall Plan to rebuild Europe, to NATO that created a cross-national military shield for Western Europe, to the creation of the UN in 1945, when the representatives of fifty countries met and signed the Charter of the United Nations in San Francisco, California ( Figure 17.4 ). Today, the United Nations, headquartered in New York City, includes 193 of the 195 nations of the world. It is a voluntary association to which member nations pay dues based on the size of their economy. The UN’s main purposes are to maintain peace and security, promote human rights and social progress, and develop friendly relationships among nations. Follow-up activity: In addition to facilitating collective decision-making on world matters, the UN carries out many different programs. Go to the UN website to find information about three different UN programs that are carried out around the world. An ongoing question for the United States in waging the war against terrorism is to what degree it should work in concert with the UN to carry out anti-terrorism initiatives around the world in a multilateral manner, rather than pursuing a “go it alone” strategy of unilateralism. The fact that the U.S. government has such a choice suggests the voluntary nature of the United States (or another country) accepting world-level governance in foreign policy. If the United States truly felt bound by UN opinion regarding the manner in which it carries out its war on terrorism, it would approach the UN Security Council for approval. Another cross-national organization to which the United States is tied, and that exists to forcefully represent Western allies and in turn forge the peace, is the North Atlantic Treaty Organization (NATO) . NATO was formed after World War II as the Cold War between East and West started to emerge. While more militaristic in approach than the United Nations, NATO has the goal of protecting the interests of Europe and the West and the assurance of support and defense from partner nations. However, while it is a strong military coalition, it has not sought to expand and take over other countries. Rather, the peace and stability of Europe are its main goals. NATO initially included only Western European nations and the United States. However, since the end of the Cold War, additional countries from the East, such as Turkey, have entered into the NATO alliance. Besides participating in the UN and NATO, the United States also distributes hundreds of millions of dollars each year in foreign aid to improve the quality of life of citizens in developing countries. The United States may also forgive the foreign debts of these countries. By definition, developing countries are not modernized in terms of infrastructure and social services and thus suffer from instability. Helping them modernize and develop stable governments is intended as a benefit to them and a prop to the stability of the world. An alternative view of U.S. assistance is that there are more nefarious goals at work, that perhaps it is intended to buy influence in developing countries, secure a position in the region, obtain access to resources, or foster dependence on the United States. The United States pursues its four main foreign policy goals through several different foreign policy types, or distinct substantive areas of foreign policy in which the United States is engaged. These types are trade, diplomacy, sanctions, military/defense, intelligence, foreign aid, and global environmental policy. Trade policy is the way the United States interacts with other countries to ease the flow of commerce and goods and services between countries. A country is said to be engaging in protectionism when it does not permit other countries to sell goods and services within its borders, or when it charges them very high tariffs (or import taxes) to do so. At the other end of the spectrum is a free trade approach, in which a country allows the unfettered flow of goods and services between itself and other countries. At times the United States has been free trade–oriented, while at other times it has been protectionist. Perhaps its most free trade–oriented move was the 1991 implementation of the North American Free Trade Agreement (NAFTA). This pact removed trade barriers and other transaction costs levied on goods moving between the United States, Mexico, and Canada. Critics see a free trade approach as problematic and instead advocate for protectionist policies that shield U.S. companies and their products against cheaper foreign products that might be imported here. One of the more prominent recent examples of protectionist policies occurred in the steel industry, as U.S. companies in the international steel marketplace struggled with competition from Chinese factories in particular. The balance of trade is the relationship between a country’s inflow and outflow of goods. The United States sells many goods and services around the world, but overall it maintains a trade deficit, in which more goods and services are coming in from other countries than are going out to be sold overseas. The current U.S. trade deficit is $37.4 billion, which means the value of what the United States imports from other countries is much larger than the value of what it exports to other countries. 4 This trade deficit has led some to advocate for protectionist trade policies. For many, foreign policy is synonymous with diplomacy. Diplomacy is the establishment and maintenance of a formal relationship between countries that governs their interactions on matters as diverse as tourism, the taxation of goods they trade, and the landing of planes on each other’s runways. While diplomatic relations are not always rosy, when they are operating it does suggest that things are going well between the countries. Diplomatic relations are formalized through the sharing of ambassadors. Ambassadors are country representatives who live and maintain an office (known as an embassy) in the other country. Just as exchanging ambassadors formalizes the bilateral relationship between countries, calling them home signifies the end of the relationship. Diplomacy tends to be the U.S. government’s first step when it tries to resolve a conflict with another country. To illustrate how international relations play out when countries come into conflict, consider what has become known as the Hainan Island incident. In 2001, a U.S. spy plane collided with a Chinese jet fighter near Chinese airspace, where U.S. planes were not authorized to be. The Chinese jet fighter crashed and the pilot died. The U.S. plane made an emergency landing on the island of Hainan. China retrieved the aircraft and captured the U.S. pilots. U.S. ambassadors then attempted to negotiate for their return. These negotiations were slow and ended up involving officials of the president’s cabinet, but they ultimately worked. Had they not succeeded, an escalating set of options likely would have included diplomatic sanctions (removal of ambassadors), economic sanctions (such as an embargo on trade and the flow of money between the countries), minor military options (such as establishment of a no-fly zone just outside Chinese airspace), or more significant military options (such as a focused campaign to enter China and get the pilots back). Nonmilitary tools to influence another country, like economic sanctions, are referred to as soft power , while the use of military power is termed hard power . 5 At the more serious end of the foreign policy decision-making spectrum, and usually as a last resort when diplomacy fails, the U.S. military and defense establishment exists to provide the United States the ability to wage war against other state and nonstate actors. Such war can be offensive, as were the Iraq War in 2003 and the 1989 removal of Panamanian leader Manuel Noriega . Or it can be defensive, as a means to respond to aggression from others, such as the Persian Gulf War in 1991, also known as Operation Desert Storm ( Figure 17.5 ). The potential for military engagement, and indeed the scattering about the globe of hundreds of U.S. military installations, can also be a potential source of foreign policy strength for the United States. On the other hand, in the world of diplomacy, such an approach can be seen as imperialistic by other world nations. Intelligence policy is related to defense and includes the overt and covert gathering of information from foreign sources that might be of strategic interest to the United States. The intelligence world, perhaps more than any other area of foreign policy, captures the imagination of the general public. Many books, television shows, and movies entertain us (with varying degrees of accuracy) through stories about U.S. intelligence operations and people. Foreign aid and global environmental policy are the final two foreign policy types. With both, as with the other types, the United States operates as a strategic actor with its own interests in mind, but here it also acts as an international steward trying to serve the common good. With foreign aid, the United States provides material and economic aid to other countries, especially developing countries, in order to improve their stability and their citizens’ quality of life. This type of aid is sometimes called humanitarian aid; in 2013 the U.S. contribution totaled $32 billion. Military aid is classified under military/defense or national security policy (and totaled $8 billion in 2013). At $40 billion the total U.S. foreign aid budget for 2013 was sizeable, though it represented less than 1 percent of the entire federal budget. 6 Global environmental policy addresses world-level environmental matters such as climate change and global warming, the thinning of the ozone layer, rainforest depletion in areas along the Equator, and ocean pollution and species extinction. The United States’ commitment to such issues has varied considerably over the years. For example, the United States was the largest country not to sign the 1997 Kyoto Protocol on greenhouse gas emissions. However, few would argue that the U.S. government has not been a leader on global environmental matters. UNIQUE CHALLENGES IN FOREIGN POLICY U.S. foreign policy is a massive and complex enterprise. What are its unique challenges for the country? First, there exists no true world-level authority dictating how the nations of the world should relate to one another. If one nation negotiates in bad faith or lies to another, there is no central world-level government authority to sanction that country. This makes diplomacy and international coordination an ongoing bargain as issues evolve and governmental leaders and nations change. Foreign relations are certainly made smoother by the existence of cross-national voluntary associations like the United Nations, the Organization of American States , and the African Union . However, these associations do not have strict enforcement authority over specific nations, unless a group of member nations takes action in some manner (which is ultimately voluntary). The European Union is the single supranational entity with some real and significant authority over its member nations. Adoption of its common currency, the euro, brings with it concessions from countries on a variety of matters, and the EU’s economic and environmental regulations are the strictest in the world. Yet even the EU has enforcement issues, as evidenced by the battle within its ranks to force member Greece to reduce its national debt or the recurring problem of Spain overfishing in the North Atlantic Ocean. International relations take place in a relatively open venue in which it is seldom clear how to achieve collective action among countries generally or between the United States and specific other nations in particular. When does it make sense to sign a multinational pact and when doesn’t it? Is a particular bilateral economic agreement truly as beneficial to the United States as to the other party, or are we giving away too much in the deal? These are open and complicated questions, which the various schools of thought discussed later in the chapter will help us answer. A second challenge for the United States is the widely differing views among countries about the role of government in people’s lives. The government of hardline communist North Korea regulates everything in its people’s lives every day. At the other end of the spectrum are countries with little government activity at all, such as parts of the island of New Guinea. In between is a vast array of diverse approaches to governance. Countries like Sweden provide cradle-to-grave human services programs like health care and education that in some parts of India are minimal at best. In Egypt, the nonprofit sector provides many services rather than the government. The United States relishes its tradition of freedom and the principle of limited government, but practice and reality can be somewhat different. In the end, it falls somewhere in the middle of this continuum because of its focus on law and order, educational and training services, and old-age pensions and health care in the form of Social Security and Medicare. The challenge of pinpointing the appropriate role of government may sound more like a domestic than a foreign policy matter, and to some degree it is an internal choice about the way government interacts with the people. Yet the internal (or domestic) relationship between a government and its people can often become intertwined with foreign policy. For example, the narrow stance on personal liberty that Iran has taken in recent decades led other countries to impose economic sanctions that crippled the country internally. Some of these sanctions have eased in light of the new nuclear deal with Iran. So the domestic and foreign policy realms are intertwined in terms of what we view as national priorities—whether they consist of nation building abroad or infrastructure building here at home, for example. This latter choice is often described as the “ guns versus butter ” debate. A third, and related, unique challenge for the United States in the foreign policy realm is other countries’ varying ideas about the appropriate form of government. These forms range from democracies on one side to various authoritarian (or nondemocratic) forms of government on the other. Relations between the United States and democratic states tend to operate more smoothly, proceeding from the shared core assumption that government’s authority comes from the people. Monarchies and other nondemocratic forms of government do not share this assumption, which can complicate foreign policy discussions immensely. People in the United States often assume that people who live in a nondemocratic country would prefer to live in a democratic one. However, in some regions of the world, such as the Middle East, this does not seem to be the case—people often prefer having stability within a nondemocratic system over changing to a less predictable democratic form of government. Or they may believe in a theocratic form of government. And the United States does have formal relations with some more totalitarian and monarchical governments, such as Saudi Arabia, when it is in U.S. interests to do so. A fourth challenge is that many new foreign policy issues transcend borders. That is, there are no longer simply friendly states and enemy states. Problems around the world that might affect the United States, such as terrorism, the international slave trade, and climate change, originate with groups and issues that are not country-specific. They are transnational. So, for example, while we can readily name the enemies of the Allied forces in World War II (Germany, Italy, and Japan), the U.S. war against terrorism has been aimed at terrorist groups that do not fit neatly within the borders of any one country with which the United States could quickly interact to solve the problem. Intelligence-gathering and focused military intervention are needed more than traditional diplomatic relations, and relations can become complicated when the United States wants to pursue terrorists within other countries’ borders. An ongoing example is the use of U.S. drone strikes on terrorist targets within the nation of Pakistan, in addition to the 2011 campaign that resulted in the death of Osama bin Laden, the founder of al-Qaeda ( Figure 17.6 ). The fifth and final unique challenge is the varying conditions of the countries in the world and their effect on what is possible in terms of foreign policy and diplomatic relations. Relations between the United States and a stable industrial democracy are going to be easier than between the United States and an unstable developing country being run by a military junta (a group that has taken control of the government by force). Moreover, an unstable country will be more focused on establishing internal stability than on broader world concerns like environmental policy. In fact, developing countries are temporarily exempt from the requirements of certain treaties while they seek to develop stable industrial and governmental frameworks. Link to Learning The Council on Foreign Relations is one of the nation’s oldest organizations that exist to promote thoughtful discussion on U.S. foreign policy. 17.2 Foreign Policy Instruments Learning Objectives By the end of this section, you will be able to: Describe the outputs of broadly focused U.S. foreign policy Describe the outputs of sharply focused U.S. foreign policy Analyze the role of Congress in foreign policy The decisions or outputs of U.S. foreign policy vary from presidential directives about conducting drone strikes to the size of the overall foreign relations budget passed by Congress, and from presidential summits with other heads of state to U.S. views of new policies considered in the UN Security Council. In this section, we consider the outputs of foreign policy produced by the U.S. government, beginning with broadly focused decisions and then discussing more sharply focused strategies. Drawing this distinction brings some clarity to the array of different policy outcomes in foreign policy. Broadly focused decisions typically take longer to formalize, bring in more actors in the United States and abroad, require more resources to carry out, are harder to reverse, and hence tend to have a lasting impact. Sharply focused outputs tend to be processed quickly, are often unilateral moves by the president, have a shorter time horizon, are easier for subsequent decision-makers to reverse, and hence do not usually have so lasting an impact as broadly focused foreign policy outputs. BROADLY FOCUSED FOREIGN POLICY OUTPUTS Broadly focused foreign policy outputs not only span multiple topics and organizations, but they also typically require large-scale spending and take longer to implement than sharply focused outputs. In the realm of broadly focused outputs, we will consider public laws, the periodic reauthorization of the foreign policy agencies, the foreign policy budget, international agreements, and the appointment process for new executive officials and ambassadors. Public Laws When we talk about new laws enacted by Congress and the president, we are referring to public laws. Public laws, sometimes called statutes, are policies that affect more than a single individual. All policies enacted by Congress and the president are public laws, except for a few dozen each year. They differ from private laws , which require some sort of action or payment by a specific individual or individuals named in the law. Many statutes affect what the government can do in the foreign policy realm, including the National Security Act , the Patriot Act , the Homeland Security Act , and the War Powers Resolution . The National Security Act governs the way the government shares and stores information, while the Patriot Act (passed immediately after 9/11) clarifies what the government may do in collecting information about people in the name of protecting the country. The Homeland Security Act of 2002 authorized the creation of a massive new federal agency, the Department of Homeland Security, consolidating powers that had been under the jurisdiction of several different agencies. Their earlier lack of coordination may have prevented the United States from recognizing warning signs of the 9/11 terrorist attacks. The War Powers Resolution was passed in 1973 by a congressional override of President Richard Nixon’s veto. The bill was Congress’s attempt to reassert itself in war-making. Congress has the power to declare war, but it had not formally done so since Japan’s 1941 attack on Pearl Harbor brought the United States into World War II. Yet the United States had entered several wars since that time, including in Korea, in Vietnam, and in focused military campaigns such as the failed 1961 Bay of Pigs invasion of Cuba. The War Powers Resolution created a new series of steps to be followed by presidents in waging military conflict with other countries. Its main feature was a requirement that presidents get approval from Congress to continue any military campaign beyond sixty days. To many, however, the overall effect was actually to strengthen the role of the president in war-making. After all, the law clarified that presidents could act on their own for sixty days before getting authorization from Congress to continue, and many smaller-scale conflicts are over within sixty days. Before the War Powers Resolution, the first approval for war was supposed to come from Congress. In theory, Congress, with its constitutional war powers, could act to reverse the actions of a president once the sixty days have passed. However, a clear disagreement between Congress and the president, especially once an initiative has begun and there is a “rally around the flag” effect, is relatively rare. More likely are tough questions about the campaign to which continuing congressional funding is tied. Reauthorization All federal agencies, including those dedicated to foreign policy, face reauthorization every three to five years. If not reauthorized, agencies lose their legal standing and the ability to spend federal funds to carry out programs. Agencies typically are reauthorized, because they coordinate carefully with presidential and congressional staff to get their affairs in order when the time comes. However, the reauthorization requirements do create a regular conversation between the agency and its political principals about how well it is functioning and what could be improved. The federal budget process is an important annual tradition that affects all areas of foreign policy. The foreign policy and defense budgets are part of the discretionary budget, or the section of the national budget that Congress vets and decides on each year. Foreign policy leaders in the executive and legislative branches must advocate for funding from this budget, and while foreign policy budgets are usually renewed, there are enough proposed changes each year to make things interesting. In addition to new agencies, new cross-national projects are proposed each year to add to infrastructure and increase or improve foreign aid, intelligence, and national security technology. Agreements International agreements represent another of the broad-based foreign policy instruments. The United States finds it useful to enter into international agreement s with other countries for a variety of reasons and on a variety of different subjects. These agreements run the gamut from bilateral agreements about tariffs to multinational agreements among dozens of countries about the treatment of prisoners of war. One recent multinational pact was the seven-country Iran Nuclear Agreement in 2015, intended to limit nuclear development in Iran in exchange for the lifting of long-standing economic sanctions on that country ( Figure 17.7 ). The format that an international agreement takes has been the point of considerable discussion in recent years. The U.S. Constitution outlines the treaty process in Article II . The president negotiates a treaty, the Senate consents to the treaty by a two-thirds vote, and finally the president ratifies it. Despite that constitutional clarity, today over 90 percent of the international agreements into which the United States enters are not treaties but rather executive agreements. 7 Executive agreements are negotiated by the president, and in the case of sole executive agreement s , they are simultaneously approved by the president as well. On the other hand, congressional-executive agreement s , like the North American Free Trade Agreement (NAFTA), are negotiated by the president and then approved by a simple majority of the House and Senate (rather than a two-thirds vote in the Senate as is the case for a treaty). In the key case of United States v. Pink (1942), the Supreme Court ruled that executive agreements were legally equivalent to treaties provided they did not alter federal law. 8 Most executive agreements are not of major importance and do not spark controversy, while some, like the Iran Nuclear Agreement, generate considerable debate. Many in the Senate thought the Iran deal should have been completed as a treaty rather than as a sole executive agreement. Finding a Middle Ground Treaty or Executive Agreement? Should new international agreements into which the United States enters be forged through the Article II treaty process of the U.S. Constitution, or through executive agreements? This question arose again in 2015 as the Iran Nuclear Agreement was being completed. That pact required Iran to halt further nuclear development and agree to nuclear inspections, while the United States and five other signatories lifted long-standing economic sanctions on Iran. The debate over whether the United States should have entered the agreement and whether it should have been a treaty rather than an executive agreement was conducted in the news media and on political comedy shows like The Daily Show . Your view on the form of the pact will depend on how you see executive agreements being employed. Do presidents use them to circumvent the Senate (as the “evasion hypothesis” suggests)? Or are they an efficient tool that saves the Senate Committee on Foreign Relations the work of processing hundreds of agreements each year? Politicians’ opinions about the form of the Iran Nuclear Agreement fell along party lines. Democrats accepted the president’s decision to use an executive agreement to finalize the pact, which they tended to support. Republicans, who were overwhelmingly against the pact, favored the use of the treaty process, which would have allowed them to vote the deal down. In the end, the president used an executive agreement and the pact was enacted. The downside is that an executive agreement can be reversed by the next president. Treaties are much more difficult to undo because they require a new process to be undertaken in the Senate in order for the president to gain approval. Which approach do you favor for the Iran Nuclear Agreement, an executive agreement or a treaty? Why? Link to Learning Watch “Under Miner” and “Start Wars” to see the take of Jon Stewart and The Daily Show on the Iran Nuclear Agreement. Appointments The last broad type of foreign policy output consists of the foreign policy appointments made when a new president takes office. Typically, when the party in the White House changes, more new appointments are made than when the party does not change, because the incoming president wants to put in place people who share his or her agenda. This was the case in 2001 when Republican George W. Bush succeeded Democrat Bill Clinton, and again in 2009 when Democrat Barack Obama succeeded Bush. Most foreign policy–related appointments, such as secretary of state and the various undersecretaries and assistant secretaries, as well as all ambassadors, must be confirmed by a majority vote of the Senate ( Figure 17.8 ). Presidents seek to nominate people who know the area to which they’re being appointed and who will be loyal to the president rather than to the bureaucracy in which they might work. They also want their nominees to be readily confirmed. As we will see in more detail later in the chapter, an isolationist group of appointees will run the country’s foreign policy agencies very differently than a group that is more internationalist in its outlook. Isolationists might seek to pull back from foreign policy involvement around the globe, while internationalists would go in the other direction, toward more involvement and toward acting in conjunction with other countries. SHARPLY FOCUSED FOREIGN POLICY OUTPUTS In addition to the broad-based foreign policy outputs above, which are president-led with some involvement from Congress, many other decisions need to be made. These sharply focused foreign policy outputs tend to be exclusively the province of the president, including the deployment of troops and/or intelligence agents in a crisis, executive summits between the president and other heads of state on targeted matters of foreign policy, presidential use of military force, and emergency funding measures to deal with foreign policy crises. These measures of foreign policy are more quickly enacted and demonstrate the “energy and dispatch” that Alexander Hamilton , writing in the Federalist Papers , saw as inherent in the institution of the presidency. Emergency spending does involve Congress through its power of the purse, but Congress tends to give presidents what they need to deal with emergencies. That said, the framers were consistent in wanting checks and balances sprinkled throughout the Constitution, including in the area of foreign policy and war powers. Hence, Congress has several roles, as discussed at points throughout this chapter. Perhaps the most famous foreign policy emergency was the Cuban Missile Crisis in 1962. With the Soviet Union placing nuclear missiles in Cuba, just a few hundred miles from Florida, a Cold War standoff with the United States escalated. The Soviets at first denied the existence of the missiles, but U.S. reconnaissance flights proved they were there, gathering photographic evidence that was presented at the UN ( Figure 17.9 ). The Soviets stood firm, and U.S. foreign policy leaders debated their approach. Some in the military were pushing for aggressive action to take out the missiles and the installation in Cuba, while State Department officials favored a diplomatic route. President John F. Kennedy ended up taking the recommendation of a special committee, and the United States implemented a naval blockade of Cuba that subtly forced the Soviets’ hands. The Soviets agreed to remove their Cuban missiles and the United States in turn agreed six months later to remove its missiles from Turkey. Link to Learning Listen to President Kennedy’s speech announcing the naval blockade the United States imposed on Cuba, ending the Cuban Missile Crisis of 1962. Another form of focused foreign policy output is the presidential summit. Often held at the Presidential Retreat at Camp David, Maryland, these meetings bring together the president and one or more other heads of state. Presidents use these types of summits when they and their visitors need to dive deeply into important issues that are not quickly solved. An example is the 1978 summit that led to the Camp David Accords, in which President Jimmy Carter, Egyptian president Anwar El Sadat, and Israeli prime minister Menachem Begin met privately for twelve days at Camp David negotiating a peace process for the two countries, which had been at odds with each other in the Middle East. Another example is the Malta Summit between President George H. W. Bush and Soviet leader Mikhail Gorbachev, which took place on the island of Malta over two days in December 1989 ( Figure 17.10 ). The meetings were an important symbol of the end of the Cold War, the Berlin Wall having come down just a few months earlier. Another focused foreign policy output is the military use of force. Since the 1941 Pearl Harbor attacks and the immediate declaration of war by Congress that resulted, all such initial uses of force have been authorized by the president. Congress in many cases has subsequently supported additional military action, but the president has been the instigator. While there has sometimes been criticism, Congress has never acted to reverse presidential action. As discussed above, the War Powers Resolution clarified that the first step in the use of force was the president’s, for the first sixty days. A recent example of the military use of force was the U.S. role in enforcing a no-fly zone over Libya in 2011, which included kinetic strikes—or active engagement of the enemy—to protect anti-government forces on the ground. U.S. fighter jets flew out of Aviano Air Base in northern Italy ( Figure 17.11 ). The final example of a focused foreign policy input is the passage of an emergency funding measure for a specific national security task. Congress tends to pass at least one emergency spending measure per year, which must be signed by the president to take effect, and it often provides funding for domestic disasters. However, at times foreign policy matters drive an emergency spending measure, as was the case right after the 9/11 attacks. In such a case, the president or the administration proposes particular amounts for emergency foreign policy plans. 17.3 Institutional Relations in Foreign Policy Learning Objectives By the end of this section, you will be able to: Describe the use of shared power in U.S. foreign policymaking Explain why presidents lead more in foreign policy than in domestic policy Discuss why individual House and Senate members rarely venture into foreign policy List the actors who engage in foreign policy Institutional relationships in foreign policy constitute a paradox. On the one hand, there are aspects of foreign policymaking that necessarily engage multiple branches of government and a multiplicity of actors. Indeed, there is a complexity to foreign policy that is bewildering, in terms of both substance and process. On the other hand, foreign policymaking can sometimes call for nothing more than for the president to make a formal decision, quickly endorsed by the legislative branch. This section will explore the institutional relationships present in U.S. foreign policymaking. FOREIGN POLICY AND SHARED POWER While presidents are more empowered by the Constitution in foreign than in domestic policy, they nonetheless must seek approval from Congress on a variety of matters; chief among these is the basic budgetary authority needed to run foreign policy programs. Indeed, most if not all of the foreign policy instruments described earlier in this chapter require interbranch approval to go into effect. Such approval may sometimes be a formality, but it is still important. Even a sole executive agreement often requires subsequent funding from Congress in order to be carried out, and funding calls for majority support from the House and Senate. Presidents lead, to be sure, but they must consult with and engage the Congress on many matters of foreign policy. Presidents must also delegate a great deal in foreign policy to the bureaucratic experts in the foreign policy agencies. Not every operation can be run from the West Wing of the White House. At bottom, the United States is a separation-of-powers political system with authority divided among executive and legislative branches, including in the foreign policy realm. Table 17.1 shows the formal roles of the president and Congress in conducting foreign policy. Roles of the President and Congress in Conducting Foreign Policy Policy Output Presidential Role Congressional Role Public laws Proposes, signs into law Proposes, approves for passage Agency reauthorizations Proposes, signs into law Approves for passage Foreign policy budget Proposes, signs into law Authorizes/appropriates for passage Treaties Negotiates, ratifies Senate consents to treaty (two-thirds) Sole executive agreements Negotiates, approves None (unless funding is required) Congressional-executive agreements Negotiates Approves by majority vote Declaration of war Proposes Approves by majority vote Military use of force Carries out operations at will (sixty days) Approves for operations beyond sixty days Presidential appointments Nominates candidates Senate approves by majority vote Table 17.1 The main lesson of Table 17.1 is that nearly all major outputs of foreign policy require a formal congressional role in order to be carried out. Foreign policy might be done by executive say-so in times of crisis and in the handful of sole executive agreements that actually pertain to major issues (like the Iran Nuclear Agreement). In general, however, a consultative relationship between the branches in foreign policy is the usual result of their constitutional sharing of power. A president who ignores Congress on matters of foreign policy and does not keep them briefed may find later interactions on other matters more difficult. Probably the most extreme version of this potential dynamic occurred during the Eisenhower presidency. When President Dwight D. Eisenhower used too many executive agreements instead of sending key ones to the Senate as treaties, Congress reacted by considering a constitutional amendment (the Bricker Amendment ) that would have altered the treaty process as we know it. Eisenhower understood the message and began to send more agreements through the process as treaties. 9 Shared power creates an incentive for the branches to cooperate. Even in the midst of a crisis, such as the Cuban Missile Crisis in 1962, it is common for the president or senior staff to brief congressional leaders in order to keep them up to speed and ensure the country can stand unified on international matters. That said, there are areas of foreign policy where the president has more discretion, such as the operation of intelligence programs, the holding of foreign policy summits, and the mobilization of troops or agents in times of crisis. Moreover, presidents have more power and influence in foreign policymaking than they do in domestic policymaking. It is to that power that we now turn. THE TWO PRESIDENCIES THESIS When the media cover a domestic controversy, such as social unrest or police brutality, reporters consult officials at different levels and in branches of government, as well as think tanks and advocacy groups. In contrast, when an international event occurs, such as a terrorist bombing in Paris or Brussels, the media flock predominately to one actor—the president of the United States—to get the official U.S. position. In the realm of foreign policy and international relations, the president occupies a leadership spot that is much clearer than in the realm of domestic policy. This dual domestic and international role has been described by the two presidencies thesis . This theory originated with University of California–Berkeley professor Aaron Wildavsky and suggests that there are two distinct presidencies, one for foreign policy and one for domestic policy, and that presidents are more successful in foreign than domestic policy. Let’s look at the reasoning behind this thesis. The Constitution names the president as the commander-in-chief of the military, the nominating authority for executive officials and ambassadors, and the initial negotiator of foreign agreements and treaties. The president is the agenda-setter for foreign policy and may move unilaterally in some instances. Beyond the Constitution, presidents were also gradually given more authority to enter into international agreements without Senate consent by using the executive agreement. We saw above that the passage of the War Powers Resolution in 1973, though intended as a statute to rein in executive power and reassert Congress as a check on the president, effectively gave presidents two months to wage war however they wish. Given all these powers, we have good reason to expect presidents to have more influence and be more successful in foreign than in domestic policy. A second reason for the stronger foreign policy presidency has to do with the informal aspects of power. In some eras, Congress will be more willing to allow the president to be a clear leader and speak for the country. For instance, the Cold War between the Eastern bloc countries (led by the Soviet Union) and the West (led by the United States and Western European allies) prompted many to want a single actor to speak for the United States. A willing Congress allowed the president to take the lead because of urgent circumstances ( Figure 17.12 ). Much of the Cold War also took place when the parties in Congress included more moderates on both sides of the aisle and the environment was less partisan than today. A phrase often heard at that time was, “Partisanship stops at the water’s edge.” This means that foreign policy matters should not be subject to the bitter disagreements seen in party politics. Does the thesis’s expectation of a more successful foreign policy presidency apply today? While the president still has stronger foreign policy powers than domestic powers, the governing context has changed in two key ways. First, the Cold War ended in 1989 with the demolition of the Berlin Wall, the subsequent disintegration of the Soviet Union, and the eventual opening up of Eastern European territories to independence and democracy. These dramatic changes removed the competitive superpower aspect of the Cold War, in which the United States and the USSR were dueling rivals on the world stage. The absence of the Cold War has led to less of a rally-behind-the-president effect in the area of foreign policy. Second, beginning in the 1980s and escalating in the 1990s, the Democratic and Republican parties began to become polarized in Congress. The moderate members in each party all but disappeared, while more ideologically motivated candidates began to win election to the House and later the Senate. Hence, the Democrats in Congress became more liberal on average, the Republicans became more conservative, and the moderates from each party, who had been able to work together, were edged out. It became increasingly likely that the party opposite the president in Congress might be more willing to challenge his initiatives, whereas in the past it was rare for the opposition party to publicly stand against the president in foreign policy. Finally, several analysts have tried applying the two presidencies thesis to contemporary presidential-congressional relationships in foreign policy. Is the two presidencies framework still valid in the more partisan post–Cold War era? The answer is mixed. On the one hand, presidents are more successful on foreign policy votes in the House and Senate, on average, than on domestic policy votes. However, the gap has narrowed. Moreover, analysis has also shown that presidents are opposed more often in Congress, even on the foreign policy votes they win. 10 Democratic leaders regularly challenged Republican George W. Bush on the Iraq War and it became common to see the most senior foreign relations committee members of the Republican Party opposing the foreign policy positions of Democratic president Barack Obama. Such challenging of the president by the opposition party simply didn’t happen during the Cold War. Therefore, it seems presidents no longer enjoy unanimous foreign policy support as they did in the early 1960s. They have to work harder to get a consensus and are more likely to face opposition. Still, because of their formal powers in foreign policy, presidents are overall more successful on foreign policy than on domestic policy. THE PERSPECTIVE OF HOUSE AND SENATE MEMBERS Congress is a bicameral legislative institution with 100 senators serving in the Senate and 435 representatives serving in the House. How interested in foreign policy are typical House and Senate members? While key White House, executive, and legislative leaders monitor and regularly weigh in on foreign policy matters, the fact is that individual representatives and senators do so much less often. Unless there is a foreign policy crisis, legislators in Congress tend to focus on domestic matters, mainly because there is not much to be gained with their constituents by pursuing foreign policy matters. 11 Domestic policy matters resonate more strongly with the voters at home. A sluggish economy, increasing health care costs, and crime matter more to them than U.S. policy toward North Korea, for example. In an open-ended Gallup poll question from early 2016 about the “most important problem” in the United States, fewer than 15 percent of respondents named a foreign policy topic (half of those respondents mentioned immigration). These results suggest that foreign policy is not at the top of many voters’ minds. In the end, legislators must be responsive to constituents in order to be good representatives and to achieve reelection. 12 However, some House and Senate members do wade into foreign policy matters. First, congressional party leaders in the majority and minority parties speak on behalf of their institution and their party on all types of issues, including foreign policy. Some House and Senate members ask to serve on the foreign policy committees, such as the Senate Committee on Foreign Relations , the House Foreign Affairs Committee , and the two defense committees ( Figure 17.13 ). These members might have military bases within their districts or states and hence have a constituency reason for being interested in foreign policy. Legislators might also simply have a personal interest in foreign policy matters that drives their engagement in the issue. Finally, they may have ambitions to move into an executive branch position that deals with foreign policy matters, such as secretary of state or defense, CIA director, or even president. Get Connected! Let People Know What You Think! Most House and Senate members do not engage in foreign policy because there is no electoral benefit to doing so. Thus, when citizens become involved, House members and senators will take notice. Research by John Kingdon on roll-call voting and by Richard Hall on committee participation found that when constituents are activated, their interest becomes salient to a legislator and he or she will respond. 13 One way you can become active in the foreign policy realm is by writing a letter or e-mail to your House member and/or your two U.S. senators about what you believe the U.S. foreign policy approach in a particular area ought to be. Perhaps you want the United States to work with other countries to protect dolphins from being accidentally trapped in tuna nets. You can also state your position in a letter to the editor of your local newspaper, or post an opinion on the newspaper’s website where a related article or op-ed piece appears. You can share links to news coverage on Facebook or Twitter and consider joining a foreign policy interest group such as Greenpeace. When you engaged in foreign policy discussion as suggested above, what type of response did you receive? Link to Learning For more information on the two key congressional committees on U.S. foreign policy, visit the Senate Committee on Foreign Relations and the House Foreign Affairs Committee websites. THE MANY ACTORS IN FOREIGN POLICY A variety of actors carry out the various and complex activities of U.S. foreign policy: White House staff, executive branch staff, and congressional leaders. The White House staff members engaged in foreign policy are likely to have very regular contact with the president about their work. The national security advisor heads the president’s National Security Council , a group of senior-level staff from multiple foreign policy agencies, and is generally the president’s top foreign policy advisor. Also reporting to the president in the White House is the director of the Central Intelligence Agency (CIA). Even more important on intelligence than the CIA director is the director of national intelligence, a position created in the government reorganizations after 9/11, who oversees the entire intelligence community in the U.S. government. The Joint Chiefs of Staff consist of six members, one each from the Army, Navy, Air Force, and Marines, plus a chair and vice chair. The chair of the Joint Chiefs of Staff is the president’s top uniformed military officer. In contrast, the secretary of defense is head of the entire Department of Defense but is a nonmilitary civilian. The U.S. trade representative develops and directs the country’s international trade agenda. Finally, within the Executive Office of the President , another important foreign policy official is the director of the president’s Office of Management and Budget (OMB). The OMB director develops the president’s yearly budget proposal, including funding for the foreign policy agencies and foreign aid. In addition to those who work directly in the White House or Executive Office of the President, several important officials work in the broader executive branch and report to the president in the area of foreign policy. Chief among these is the secretary of state. The secretary of state is the nation’s chief diplomat, serves in the president’s cabinet, and oversees the Foreign Service. The secretary of defense, who is the civilian (nonmilitary) head of the armed services housed in the Department of Defense , is also a key cabinet member for foreign policy (as mentioned above). A third cabinet secretary, the secretary of homeland security, is critically important in foreign policy, overseeing the massive Department of Homeland Security ( Figure 17.14 ). Insider Perspective Former Secretary of Defense Robert Gates Former secretary of defense Robert Gates served under both Republican and Democratic presidents. First Gates rose through the ranks of the CIA to become the director during the George H. W. Bush administration. He then left government to serve as an academic administrator at Texas A&M University in College Station, Texas, where he rose to the position of university president. He was able to win over reluctant faculty and advance the university’s position, including increasing the faculty at a time when budgets were in decline in Texas. Then, when Secretary of Defense Donald Rumsfeld resigned, President George W. Bush invited Gates to return to government service as Rumsfeld’s replacement. Gates agreed, serving in that capacity for the remainder of the Bush years and then for several years in the Obama administration before retiring from government service a second time ( Figure 17.15 ). He has generally been seen as thorough, systematic, and fair. In his memoir, Duty: Memoirs of a Secretary at War , 14 Secretary Gates takes issue with the actions of both the presidents for whom he worked, but ultimately he praises them for their service and for upholding the right principles in protecting the United States and U.S. military troops. In this and earlier books, Gates discusses the need to have an overarching plan but says plans cannot be too tight or they will fail when things change in the external environment. After leaving politics, Gates served as president of the Boy Scouts of America, where he presided over the change in policy that allowed openly gay scouts and leaders, an issue with which he had had experience as secretary of defense under President Obama. In that role Gates oversaw the end of the military’s “Don’t ask, don’t tell” policy. 15 What do you think about a cabinet secretary serving presidents from two different political parties? Is this is a good idea? Why or why not? The final group of official key actors in foreign policy are in the U.S. Congress. The Speaker of the House, the House minority leader, and the Senate majority and minority leaders are often given updates on foreign policy matters by the president or the president’s staff. They are also consulted when the president needs foreign policy support or funding. However, the experts in Congress who are most often called on for their views are the committee chairs and the highest-ranking minority members of the relevant House and Senate committees. In the House, that means the Foreign Affairs Committee and the Committee on Armed Services. In the Senate, the relevant committees are the Committee on Foreign Relations and the Armed Services Committee. These committees hold regular hearings on key foreign policy topics, consider budget authorizations, and debate the future of U.S. foreign policy. 17.4 Approaches to Foreign Policy Learning Objectives By the end of this section, you will be able to: Explain classic schools of thought on U.S. foreign policy Describe contemporary schools of thought on U.S. foreign policy Delineate the U.S. foreign policy approach with Russia and China Frameworks and theories help us make sense of the environment of governance in a complex area like foreign policy. A variety of schools of thought exist about how to approach foreign policy, each with different ideas about what “should” be done. These approaches also vary in terms of what they assume about human nature, how many other countries ought to be involved in U.S. foreign policy, and what the tenor of foreign policymaking ought to be. They help us situate the current U.S. approach to many foreign policy challenges around the world. CLASSIC APPROACHES A variety of traditional concepts of foreign policy remain helpful today as we consider the proper role of the United States in, and its approach to, foreign affairs. These include isolationism, the idealism versus realism debate, liberal internationalism, hard versus soft power, and the grand strategy of U.S. foreign policy. From the end of the Revolutionary War in the late eighteenth century until the early twentieth century, isolationism —whereby a country stays out of foreign entanglements and keeps to itself—was a popular stance in U.S. foreign policy. Among the founders, Thomas Jefferson especially was an advocate of isolationism or non-involvement. He thought that by keeping to itself, the United States stood a better chance of becoming a truly free nation. This fact is full of irony, because Jefferson later served as ambassador to France and president of the United States, both roles that required at least some attention to foreign policy. Still, Jefferson’s ideas had broad support. After all, Europe was where volatile changes were occurring. The new nation was tired of war, and there was no reason for it to be entangled militarily with anyone. Indeed, in his farewell address, President George Washington famously warned against the creation of “entangling alliances.” 16 Despite this legacy, the United States was pulled squarely into world affairs with its entry into World War I. But between the Armistice in 1918 that ended that war and U.S. entry into World War II in 1941, isolationist sentiment returned, based on the idea that Europe should learn to govern its own affairs. Then, after World War II, the United States engaged the world stage as one of two superpowers and the military leader of Europe and the Pacific. Isolationism never completely went away, but now it operated in the background. Again, Europe seemed to be the center of the problem, while political life in the United States seemed calmer somehow. The end of the Cold War opened up old wounds as a variety of smaller European countries sought independence and old ethnic conflicts reappeared. Some in the United States felt the country should again be isolationist as the world settled into a new political arrangement, including a vocal senator, Jesse Helms (R-NC), who was against the United States continuing to be the military “policeman” of the world. Helms was famous for opposing nearly all treaties brought to the Senate during his tenure. Congressman Ron Paul (R-TX) and his son Senator Rand Paul (R-KY) were both isolationist candidates for the presidency (in 2008 and 2016, respectively); both thought the United States should retreat from foreign entanglements, spend far less on military and foreign policy, and focus more on domestic issues. At the other end of the spectrum is liberal internationalism . Liberal internationalism advocates a foreign policy approach in which the United States becomes proactively engaged in world affairs. Its adherents assume that liberal democracies must take the lead in creating a peaceful world by cooperating as a community of nations and creating effective world structures such as the United Nations. To fully understand liberal internationalism, it is helpful to understand the idealist versus realist debate in international relations. Idealists assume the best in others and see it as possible for countries to run the world together, with open diplomacy, freedom of the seas, free trade, and no militaries. Everyone will take care of each other. There is an element of idealism in liberal internationalism, because the United States assumes other countries will also put their best foot forward. A classic example of a liberal internationalist is President Woodrow Wilson , who sought a League of Nations to voluntarily save the world after World War I. Realists assume that others will act in their own self-interest and hence cannot necessarily be trusted. They want a healthy military and contracts between countries in case others want to wiggle out of their commitments. Realism also has a place in liberal internationalism, because the United States approaches foreign relationships with open eyes and an emphasis on self-preservation. Soft power, or diplomacy, with which the United States often begins a foreign policy relationship or entanglement, is in line with liberal internationalism and idealism, while hard power, which allows the potential for military force, is the stuff of realism. For example, at first the United States was rather isolationist in its approach to China, assuming it was a developing country of little impact that could safely be ignored. Then President Nixon opened up China as an area for U.S. investment, and an era of open diplomatic relations began in the early 1970s ( Figure 17.16 ). As China modernized and began to dominate the trade relationship with the United States, many came to see it through a realist lens and to consider whether China’s behavior really warranted its beneficial most-favored-nation trading status. The final classic idea of foreign policy is the so-called grand strategy—employing all available diplomatic, economic, and military resources to advance the national interest. The grand strategy invokes the possibility of hard power, because it relies on developing clear strategic directions for U.S. foreign policy and the methods to achieve those goals, often with military capability attached. The U.S. foreign policy plan in Europe and Asia after World War II reflects a grand strategy approach. In order to stabilize the world, the United States built military bases in Italy, Germany, Spain, England, Belgium, Japan, Guam, and Korea. It still operates nearly all these, though often under a multinational arrangement such as NATO. These bases help preserve stability on the one hand, and U.S. influence on the other. MORE RECENT SCHOOLS OF THOUGHTS Two particular events in foreign policy caused many to change their views about the proper approach to U.S. involvement in world affairs. First, the debacle of U.S. involvement in the civil war in Vietnam in the years leading up to 1973 caused many to rethink the country’s traditional containment approach to the Cold War. Containment was the U.S. foreign policy goal of limiting the spread of communism. In Vietnam the United States supported one governing faction within the country (democratic South Vietnam), whereas the Soviet Union supported the opposing governing faction (communist North Vietnam). The U.S. military approach of battlefield engagement did not translate well to the jungles of Vietnam, where “guerilla warfare” predominated. Skeptics became particularly pessimistic about liberal internationalism given how poorly the conflict in Vietnam had played out. U.S. military forces withdrew from South Vietnam in 1973, and Saigon, its capital, fell to North Vietnam and the communists eighteen months later. Many of those pessimists then became neoconservatives on foreign policy. Neoconservatives believe that rather than exercising restraint and always using international organizations as the path to international outcomes, the United States should aggressively use its might to promote its values and ideals around the world. The aggressive use (or threat) of hard power is the core value of neoconservatism . Acting unilaterally is acceptable in this view, as is adopting a preemptive strategy in which the United States intervenes militarily before the enemy can make its move. Preemption is a new idea; the United States has tended to be retaliatory in its use of military force, as in the case of Pearl Harbor at the start of World War II. Examples of neoconservativism in action are the 1980s U.S. campaigns in Central American countries to turn back communism under President Ronald Reagan, the Iraq War of 2003 led by President George W. Bush and his vice president Dick Cheney ( Figure 17.17 ), and the use of drones as counterterrorism weapons during the Obama administration. Neo-isolationism, like earlier isolationism, advocates keeping free of foreign entanglements. Yet no advanced industrial democracy completely separates itself from the rest of the world. Foreign markets beckon, tourism helps spur economic development at home and abroad, and global environmental challenges require cross-national conversation. In the twenty-first century, neo-isolationism means distancing the United States from the United Nations and other international organizations that get in the way. The strategy of selective engagement —retaining a strong military presence and remaining engaged across the world through alliances and formal installations—is used to protect the national security interests of the United States. However, this strategy also seeks to avoid being the world’s policeman. The second factor that changed minds about twenty-first century foreign policy is the rise of elusive new enemies who defy traditional designations. Rather than countries, these enemies are terrorist groups such as al-Qaeda and ISIS (or ISIL) that spread across national boundaries. A hybrid approach to U.S. foreign policy that uses multiple schools of thought as circumstances warrant may thus be the wave of the future. President Obama often took a hybrid approach. In some respects, he was a liberal internationalist seeking to put together broad coalitions to carry out world business. At the same time, his sending teams of troops and drones to take out terrorist targets in other legitimate nation-states without those states’ approval fits with a neoconservative approach. Finally, his desire to not be the “world’s policeman” led him to follow a practice of selective engagement. Link to Learning Several interest groups debate what should happen in U.S. foreign policy, many of which are included in this list compiled by project Vote Smart. U.S. FOREIGN POLICY IN THE COLD WAR AND WITH CHINA The foreign policy environment from the end of World War II until the end of the Cold War in 1990 was dominated by a duel of superpowers between the United States and its Western allies on the one hand and the Soviet Union and the communist bloc of countries in the East on the other. Both superpowers developed thousands of weapons of mass destruction and readied for a potential world war to be fought with nuclear weapons. That period was certainly challenging and ominous at times, but it was simpler than the present era. Nations knew what team they were on, and there was generally an incentive to not go to war because it would lead to the unthinkable—the end of the Earth as we know it, or mutually assured destruction. The result of this logic, essentially a standoff between the two powers, is sometime referred to as nuclear deterrence. When the Soviet Union imploded and the Cold War ended, it was in many ways a victory for the West and for democracy. However, once the bilateral nature of the Cold War was gone, dozens of countries sought independence and old ethnic conflicts emerged in several regions of the world, including Eastern Europe. This new era holds great promise, but it is in many ways more complex than the Cold War. The rise of cross-national terrorist organizations further complicates the equation because the enemy hides within the borders of potentially dozens of countries around the globe. In summary, the United States pursues a variety of topics and goals in different areas of the world in the twenty-first century. The Soviet Union dissolved into many component parts after the Cold War, including Russia, various former Soviet republics like Georgia and Ukraine, and smaller nation-states in Eastern Europe, such as the Czech Republic. The general approach of the United States has been to encourage the adoption of democracy and economic reforms in these former Eastern bloc countries. Many of them now align with the EU and even with the West’s cross-national military organization, NATO. With freedoms can come conflict, and there has been much of that in these fledgling countries as opposition coalitions debate how the future course should be charted, and by whom. Under President Vladimir Putin , Russia is again trying to strengthen its power on the country’s western border, testing expansionism while invoking Russian nationalism. The United States is adopting a defensive position and trying to prevent the spread of Russian influence. The EU and NATO factor in here from the standpoint of an internationalist approach. In many ways the more visible future threat to the United States is China, the potential rival superpower of the future. A communist state that has also encouraged much economic development, China has been growing and modernizing for more than thirty years. Its nearly 1.4 billion citizens are stepping onto the world economic stage with other advanced industrial nations. In addition to fueling an explosion of industrial domestic development, public and private Chinese investors have spread their resources to every continent and most countries of the world. Indeed, Chinese investors lend money to the United States government on a regular basis, as U.S. domestic borrowing capacity is pushed to the limit in most years. Many in the United States are worried by the lack of freedom and human rights in China. During the Tiananmen Square massacre in Beijing on June 4, 1989, thousands of pro-democracy protestors were arrested and many were killed as Chinese authorities fired into the crowd and tanks crushed people who attempted to wall them out. Over one thousand more dissidents were arrested in the following weeks as the Chinese government investigated the planning of the protests in the square. The United States instituted minor sanctions for a time, but President George H. W. Bush chose not to remove the most-favored-nation trading status of this long-time economic partner. Most in the U.S. government, including leaders in both political parties, wish to engage China as an economic partner at the same time that they keep a watchful eye on its increasing influence around the world, especially in developing countries. Elsewhere in Asia, the United States has good relationships with most other countries, especially South Korea and Japan, which have both followed paths the United States favored after World War II. Both countries embraced democracy, market-oriented economies, and the hosting of U.S. military bases to stabilize the region. North Korea, however, is another matter. A closed, communist, totalitarian regime, North Korea has been testing nuclear bombs in recent decades, to the concern of the rest of the world. Like China many decades earlier, India is a developing country with a large population that is expanding and modernizing. Unlike China, India has embraced democracy, especially at the local level. Link to Learning You can plot U.S. government attention to different types of policy matters (including international affairs and foreign aid and its several dozen more focused subtopics) by using the online trend analysis tool at the Comparative Agendas Project.
psychology
Summary 9.1 What Is Lifespan Development? Lifespan development explores how we change and grow from conception to death. This field of psychology is studied by developmental psychologists. They view development as a lifelong process that can be studied scientifically across three developmental domains: physical, cognitive development, and psychosocial. There are several theories of development that focus on the following issues: whether development is continuous or discontinuous, whether development follows one course or many, and the relative influence of nature versus nurture on development. 9.2 Lifespan Theories There are many theories regarding how babies and children grow and develop into happy, healthy adults. Sigmund Freud suggested that we pass through a series of psychosexual stages in which our energy is focused on certain erogenous zones on the body. Eric Erikson modified Freud’s ideas and suggested a theory of psychosocial development. Erikson said that our social interactions and successful completion of social tasks shape our sense of self. Jean Piaget proposed a theory of cognitive development that explains how children think and reason as they move through various stages. Finally, Lawrence Kohlberg turned his attention to moral development. He said that we pass through three levels of moral thinking that build on our cognitive development. 9.3 Stages of Development At conception the egg and sperm cell are united to form a zygote, which will begin to divide rapidly. This marks the beginning of the first stage of prenatal development (germinal stage), which lasts about two weeks. Then the zygote implants itself into the lining of the woman’s uterus, marking the beginning of the second stage of prenatal development (embryonic stage), which lasts about six weeks. The embryo begins to develop body and organ structures, and the neural tube forms, which will later become the brain and spinal cord. The third phase of prenatal development (fetal stage) begins at 9 weeks and lasts until birth. The body, brain, and organs grow rapidly during this stage. During all stages of pregnancy it is important that the mother receive prenatal care to reduce health risks to herself and to her developing baby. Newborn infants weigh about 7.5 pounds. Doctors assess a newborn’s reflexes, such as the sucking, rooting, and Moro reflexes. Our physical, cognitive, and psychosocial skills grow and change as we move through developmental stages from infancy through late adulthood. Attachment in infancy is a critical component of healthy development. Parenting styles have been found to have an effect on childhood outcomes of well-being. The transition from adolescence to adulthood can be challenging due to the timing of puberty, and due to the extended amount of time spent in emerging adulthood. Although physical decline begins in middle adulthood, cognitive decline does not begin until later. Activities that keep the body and mind active can help maintain good physical and cognitive health as we age. Social supports through family and friends remain important as we age. 9.4 Death and Dying Death marks the endpoint of our lifespan. There are many ways that we might react when facing death. Kübler-Ross developed a five-stage model of grief as a way to explain this process. Many people facing death choose hospice care, which allows their last days to be spent at home in a comfortable, supportive environment.
Chapter Outline 9.1 What Is Lifespan Development? 9.2 Lifespan Theories 9.3 Stages of Development 9.4 Death and Dying Introduction Welcome to the story of your life. In this chapter we explore the fascinating tale of how you have grown and developed into the person you are today. We also look at some ideas about who you will grow into tomorrow. Yours is a story of lifespan development ( Figure 9.1 ), from the start of life to the end. The process of human growth and development is more obvious in infancy and childhood, yet your development is happening this moment and will continue, minute by minute, for the rest of your life. Who you are today and who you will be in the future depends on a blend of genetics, environment, culture, relationships, and more, as you continue through each phase of life. You have experienced firsthand much of what is discussed in this chapter. Now consider what psychological science has to say about your physical, cognitive, and psychosocial development, from the womb to the tomb.
[ { "answer": { "ans_choice": 2, "ans_text": "continuous development" }, "bloom": null, "hl_context": "<hl> Continuous development views development as a cumulative process , gradually improving on existing skills ( Figure 9.2 ) . <hl> With this type of development , there is gradual change . Consider , for example , a child ’ s physical growth : adding inches to her height year by year . In contrast , theorists who view development as discontinuous believe that development takes place in unique stages : It occurs at specific times or ages . With this type of development , the change is more sudden , such as an infant ’ s ability to conceive object permanence .", "hl_sentences": "Continuous development views development as a cumulative process , gradually improving on existing skills ( Figure 9.2 ) .", "question": { "cloze_format": "The view that development is a cumulative process, gradually adding to the same type of skills is known as ________.", "normal_format": "What is known as the view that development is a cumulative process, gradually adding to the same type of skills?", "question_choices": [ "nature", "nurture", "continuous development", "discontinuous development" ], "question_id": "fs-idp31468640", "question_text": "The view that development is a cumulative process, gradually adding to the same type of skills is known as ________." }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 1, "ans_text": "psychological" }, "bloom": null, "hl_context": "These are the types of questions developmental psychologists try to answer , by studying how humans change and grow from conception through childhood , adolescence , adulthood , and death . <hl> They view development as a lifelong process that can be studied scientifically across three developmental domains — physical , cognitive , and psychosocial development . <hl> Physical development involves growth and changes in the body and brain , the senses , motor skills , and health and wellness . Cognitive development involves learning , attention , memory , language , thinking , reasoning , and creativity . Psychosocial development involves emotions , personality , and social relationships . We refer to these domains throughout the chapter . The process of human growth and development is more obvious in infancy and childhood , yet your development is happening this moment and will continue , minute by minute , for the rest of your life . Who you are today and who you will be in the future depends on a blend of genetics , environment , culture , relationships , and more , as you continue through each phase of life . You have experienced firsthand much of what is discussed in this chapter . <hl> Now consider what psychological science has to say about your physical , cognitive , and psychosocial development , from the womb to the tomb . <hl>", "hl_sentences": "They view development as a lifelong process that can be studied scientifically across three developmental domains — physical , cognitive , and psychosocial development . Now consider what psychological science has to say about your physical , cognitive , and psychosocial development , from the womb to the tomb .", "question": { "cloze_format": "Developmental psychologists study human growth and development, but not the ___ domain.", "normal_format": "Developmental psychologists study human growth and development across three domains. Which of the following is not one of these domains?", "question_choices": [ "cognitive", "psychological", "physical", "psychosocial" ], "question_id": "fs-idp531136", "question_text": "Developmental psychologists study human growth and development across three domains. Which of the following is not one of these domains?" }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 0, "ans_text": "The study of how we grow and change from conception to death." }, "bloom": null, "hl_context": "<hl> These are the types of questions developmental psychologists try to answer , by studying how humans change and grow from conception through childhood , adolescence , adulthood , and death . <hl> <hl> They view development as a lifelong process that can be studied scientifically across three developmental domains — physical , cognitive , and psychosocial development . <hl> Physical development involves growth and changes in the body and brain , the senses , motor skills , and health and wellness . Cognitive development involves learning , attention , memory , language , thinking , reasoning , and creativity . Psychosocial development involves emotions , personality , and social relationships . We refer to these domains throughout the chapter .", "hl_sentences": "These are the types of questions developmental psychologists try to answer , by studying how humans change and grow from conception through childhood , adolescence , adulthood , and death . They view development as a lifelong process that can be studied scientifically across three developmental domains — physical , cognitive , and psychosocial development .", "question": { "cloze_format": "Lifespan development is defined as ___.", "normal_format": "How is lifespan development defined?", "question_choices": [ "The study of how we grow and change from conception to death.", "The study of how we grow and change in infancy and childhood.", "The study of physical, cognitive, and psychosocial growth in children.", "The study of emotions, personality, and social relationships." ], "question_id": "fs-idm81545504", "question_text": "How is lifespan development defined?" }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 1, "ans_text": "object permanence" }, "bloom": null, "hl_context": "Just as there are physical milestones that we expect children to reach , there are also cognitive milestones . It is helpful to be aware of these milestones as children gain new abilities to think , problem solve , and communicate . For example , infants shake their head “ no ” around 6 – 9 months , and they respond to verbal requests to do things like “ wave bye-bye ” or “ blow a kiss ” around 9 – 12 months . <hl> Remember Piaget ’ s ideas about object permanence ? <hl> <hl> We can expect children to grasp the concept that objects continue to exist even when they are not in sight by around 8 months old . <hl> Because toddlers ( i . e . , 12 – 24 months old ) have mastered object permanence , they enjoy games like hide and seek , and they realize that when someone leaves the room they will come back ( Loop , 2013 ) . Toddlers also point to pictures in books and look in appropriate places when you ask them to find objects . Table 9.2 Piaget ’ s Stages of Cognitive Development The first stage is the sensorimotor stage , which lasts from birth to about 2 years old . During this stage , children learn about the world through their senses and motor behavior . Young children put objects in their mouths to see if the items are edible , and once they can grasp objects , they may shake or bang them to see if they make sounds . <hl> Between 5 and 8 months old , the child develops object permanence , which is the understanding that even if something is out of sight , it still exists ( Bogartz , Shinskey , & Schilling , 2000 ) . <hl> According to Piaget , young infants do not remember an object after it has been removed from sight . Piaget studied infants ’ reactions when a toy was first shown to an infant and then hidden under a blanket . Infants who had already developed object permanence would reach for the hidden toy , indicating that they knew it still existed , whereas infants who had not developed object permanence would appear confused .", "hl_sentences": "Remember Piaget ’ s ideas about object permanence ? We can expect children to grasp the concept that objects continue to exist even when they are not in sight by around 8 months old . Between 5 and 8 months old , the child develops object permanence , which is the understanding that even if something is out of sight , it still exists ( Bogartz , Shinskey , & Schilling , 2000 ) .", "question": { "cloze_format": "The idea that even if something is out of sight, it still exists is called ________.", "normal_format": "What is the idea that even if something is out of sight, it still exists called?", "question_choices": [ "egocentrism", "object permanence", "conservation", "reversibility" ], "question_id": "fs-idm89116704", "question_text": "The idea that even if something is out of sight, it still exists is called ________." }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 3, "ans_text": "Lawrence Kohlberg" }, "bloom": null, "hl_context": "<hl> After presenting people with this and various other moral dilemmas , Kohlberg reviewed people ’ s responses and placed them in different stages of moral reasoning ( Figure 9.6 ) . <hl> According to Kohlberg , an individual progresses from the capacity for pre-conventional morality ( before age 9 ) to the capacity for conventional morality ( early adolescence ) , and toward attaining post-conventional morality ( once formal operational thought is attained ) , which only a few fully achieve . Kohlberg placed in the highest stage responses that reflected the reasoning that Heinz should steal the drug because his wife ’ s life is more important than the pharmacist making money . The value of a human life overrides the pharmacist ’ s greed . A major task beginning in childhood and continuing into adolescence is discerning right from wrong . Psychologist Lawrence Kohlberg ( 1927 – 1987 ) extended upon the foundation that Piaget built regarding cognitive development . <hl> Kohlberg believed that moral development , like cognitive development , follows a series of stages . <hl> To develop this theory , Kohlberg posed moral dilemmas to people of all ages , and then he analyzed their answers to find evidence of their particular stage of moral development . Before reading about the stages , take a minute to consider how you would answer one of Kohlberg's best-known moral dilemmas , commonly known as the Heinz dilemma :", "hl_sentences": "After presenting people with this and various other moral dilemmas , Kohlberg reviewed people ’ s responses and placed them in different stages of moral reasoning ( Figure 9.6 ) . Kohlberg believed that moral development , like cognitive development , follows a series of stages .", "question": { "cloze_format": "____ proposed that moral thinking proceeds trough a series of stages.", "normal_format": "Which theorist proposed that moral thinking proceeds through a series of stages?", "question_choices": [ "Sigmund Freud", "Erik Erikson", "John Watson", "Lawrence Kohlberg" ], "question_id": "fs-idm76278928", "question_text": "Which theorist proposed that moral thinking proceeds through a series of stages?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 2, "ans_text": "forming an identity" }, "bloom": null, "hl_context": "Adolescents continue to refine their sense of self as they relate to others . <hl> Erikson referred to the task of the adolescent as one of identity versus role confusion . <hl> Thus , in Erikson ’ s view , an adolescent ’ s main questions are “ Who am I ? ” and “ Who do I want to be ? ” Some adolescents adopt the values and roles that their parents expect for them . Other teens develop identities that are in opposition to their parents but align with a peer group . This is common as peer relationships become a central focus in adolescents ’ lives . <hl> In adolescence ( ages 12 – 18 ) , children face the task of identity versus role confusion . <hl> <hl> According to Erikson , an adolescent ’ s main task is developing a sense of self . <hl> Adolescents struggle with questions such as “ Who am I ? ” and “ What do I want to do with my life ? ” Along the way , most adolescents try on many different selves to see which ones fit . Adolescents who are successful at this stage have a strong sense of identity and are able to remain true to their beliefs and values in the face of problems and other people ’ s perspectives . What happens to apathetic adolescents , who do not make a conscious search for identity , or those who are pressured to conform to their parents ’ ideas for the future ? These teens will have a weak sense of self and experience role confusion . They are unsure of their identity and confused about the future .", "hl_sentences": "Erikson referred to the task of the adolescent as one of identity versus role confusion . In adolescence ( ages 12 – 18 ) , children face the task of identity versus role confusion . According to Erikson , an adolescent ’ s main task is developing a sense of self .", "question": { "cloze_format": "According to Erikson's theory of psychosocial development, the main task of the adolescent is ___.", "normal_format": "According to Erikson’s theory of psychosocial development, what is the main task of the adolescent?", "question_choices": [ "developing autonomy", "feeling competent", "forming an identity", "forming intimate relationships" ], "question_id": "fs-idm8486576", "question_text": "According to Erikson’s theory of psychosocial development, what is the main task of the adolescent?" }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 3, "ans_text": "zygote, embryo, fetus" }, "bloom": null, "hl_context": "<hl> When the organism is about nine weeks old , the embryo is called a fetus . <hl> At this stage , the fetus is about the size of a kidney bean and begins to take on the recognizable form of a human being as the “ tail ” begins to disappear . <hl> After the zygote divides for about 7 – 10 days and has 150 cells , it travels down the fallopian tubes and implants itself in the lining of the uterus . <hl> Upon implantation , this multi-cellular organism is called an embryo . Now blood vessels grow , forming the placenta . The placenta is a structure connected to the uterus that provides nourishment and oxygen from the mother to the developing embryo via the umbilical cord . Basic structures of the embryo start to develop into areas that will become the head , chest , and abdomen . During the embryonic stage , the heart begins to beat and organs form and begin to function . The neural tube forms along the back of the embryo , developing into the spinal cord and brain .", "hl_sentences": "When the organism is about nine weeks old , the embryo is called a fetus . After the zygote divides for about 7 – 10 days and has 150 cells , it travels down the fallopian tubes and implants itself in the lining of the uterus .", "question": { "cloze_format": "___ is the correct order of prenatal development.", "normal_format": "Which of the following is the correct order of prenatal development?", "question_choices": [ "zygote, fetus, embryo", "fetus, embryo zygote", "fetus, zygote, embryo", "zygote, embryo, fetus" ], "question_id": "fs-idm108479040", "question_text": "Which of the following is the correct order of prenatal development?" }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 0, "ans_text": "critical period" }, "bloom": null, "hl_context": "<hl> Each organ of the fetus develops during a specific period in the pregnancy , called the critical or sensitive period ( Figure 9.8 ) . <hl> For example , research with primate models of FASD has demonstrated that the time during which a developing fetus is exposed to alcohol can dramatically affect the appearance of facial characteristics associated with fetal alcohol syndrome . Specifically , this research suggests that alcohol exposure that is limited to day 19 or 20 of gestation can lead to significant facial abnormalities in the offspring ( Ashley , Magnuson , Omnell , & Clarren , 1999 ) . Given regions of the brain also show sensitive periods during which they are most susceptible to the teratogenic effects of alcohol ( Tran & Kelly , 2003 ) . What Do You Think ? Should Women Who Use Drugs During Pregnancy Be Arrested and Jailed ? As you now know , women who use drugs or alcohol during pregnancy can cause serious lifelong harm to their child . Some people have advocated mandatory screenings for women who are pregnant and have a history of drug abuse , and if the women continue using , to arrest , prosecute , and incarcerate them ( Figdor & Kaeser , 1998 ) . This policy was tried in Charleston , South Carolina , as recently as 20 years ago . The policy was called the Interagency Policy on Management of Substance Abuse During Pregnancy , and had disastrous results .", "hl_sentences": "Each organ of the fetus develops during a specific period in the pregnancy , called the critical or sensitive period ( Figure 9.8 ) .", "question": { "cloze_format": "The time during fetal growth when specific parts or organs develop is known as ________.", "normal_format": "What is the time during fetal growth when specific parts or organs develop?", "question_choices": [ "critical period", "mitosis", "conception", "pregnancy" ], "question_id": "fs-idm72750912", "question_text": "The time during fetal growth when specific parts or organs develop is known as ________." }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 2, "ans_text": "zygote" }, "bloom": null, "hl_context": "In the discussion of biopsychology earlier in the book , you learned about genetics and DNA . A mother and father ’ s DNA is passed on to the child at the moment of conception . Conception occurs when sperm fertilizes an egg and forms a zygote ( Figure 9.7 ) . <hl> A zygote begins as a one-cell structure that is created when a sperm and egg merge . <hl> The genetic makeup and sex of the baby are set at this point . During the first week after conception , the zygote divides and multiplies , going from a one-cell structure to two cells , then four cells , then eight cells , and so on . This process of cell division is called mitosis . Mitosis is a fragile process , and fewer than one-half of all zygotes survive beyond the first two weeks ( Hall , 2004 ) . After 5 days of mitosis there are 100 cells , and after 9 months there are billions of cells . As the cells divide , they become more specialized , forming different organs and body parts . In the germinal stage , the mass of cells has yet to attach itself to the lining of the mother ’ s uterus . Once it does , the next stage begins .", "hl_sentences": "A zygote begins as a one-cell structure that is created when a sperm and egg merge .", "question": { "cloze_format": "___ begins as a single-cell structure that is created when a sperm and egg merge at conception.", "normal_format": "What begins as a single-cell structure that is created when a sperm and egg merge at conception?", "question_choices": [ "embryo", "fetus", "zygote", "infant" ], "question_id": "fs-idm139297712", "question_text": "What begins as a single-cell structure that is created when a sperm and egg merge at conception?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 1, "ans_text": "fine motor skills" }, "bloom": null, "hl_context": "Motor skills refer to our ability to move our bodies and manipulate objects . <hl> Fine motor skills focus on the muscles in our fingers , toes , and eyes , and enable coordination of small actions ( e . g . , grasping a toy , writing with a pencil , and using a spoon ) . <hl> Gross motor skills focus on large muscle groups that control our arms and legs and involve larger movements ( e . g . , balancing , running , and jumping ) .", "hl_sentences": "Fine motor skills focus on the muscles in our fingers , toes , and eyes , and enable coordination of small actions ( e . g . , grasping a toy , writing with a pencil , and using a spoon ) .", "question": { "cloze_format": "Using scissors to cut out paper shapes is an example of ________.", "normal_format": "What is using scissors to cut out paper shapes an example of?", "question_choices": [ "gross motor skills", "fine motor skills", "large motor skills", "small motor skills" ], "question_id": "fs-idm721680", "question_text": "Using scissors to cut out paper shapes is an example of ________." }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 0, "ans_text": "secure" }, "bloom": null, "hl_context": "<hl> Based on how the infants / toddlers responded to the separation and reunion , Ainsworth identified three types of parent-child attachments : secure , avoidant , and resistant ( Ainsworth & Bell , 1970 ) . <hl> A fourth style , known as disorganized attachment , was later described ( Main & Solomon , 1990 ) . The most common type of attachment — also considered the healthiest — is called secure attachment ( Figure 9.14 ) . <hl> In this type of attachment , the toddler prefers his parent over a stranger . <hl> <hl> The attachment figure is used as a secure base to explore the environment and is sought out in times of stress . <hl> Securely attached children were distressed when their caregivers left the room in the Strange Situation experiment , but when their caregivers returned , the securely attached children were happy to see them . Securely attached children have caregivers who are sensitive and responsive to their needs . Building on the work of Harlow and others , John Bowlby developed the concept of attachment theory . He defined attachment as the affectional bond or tie that an infant forms with the mother ( Bowlby , 1969 ) . An infant must form this bond with a primary caregiver in order to have normal social and emotional development . In addition , Bowlby proposed that this attachment bond is very powerful and continues throughout life . <hl> He used the concept of secure base to define a healthy attachment between parent and child ( 1988 ) . <hl> <hl> A secure base is a parental presence that gives the child a sense of safety as he explores his surroundings . <hl> Bowlby said that two things are needed for a healthy attachment : The caregiver must be responsive to the child ’ s physical , social , and emotional needs ; and the caregiver and child must engage in mutually enjoyable interactions ( Bowlby , 1969 ) ( Figure 9.13 ) .", "hl_sentences": "Based on how the infants / toddlers responded to the separation and reunion , Ainsworth identified three types of parent-child attachments : secure , avoidant , and resistant ( Ainsworth & Bell , 1970 ) . In this type of attachment , the toddler prefers his parent over a stranger . The attachment figure is used as a secure base to explore the environment and is sought out in times of stress . He used the concept of secure base to define a healthy attachment between parent and child ( 1988 ) . A secure base is a parental presence that gives the child a sense of safety as he explores his surroundings .", "question": { "cloze_format": "The child uses the parent as a base from which to explore her world in the ___ attachment style.", "normal_format": "The child uses the parent as a base from which to explore her world in which attachment style?", "question_choices": [ "secure", "insecure avoidant", "insecure ambivalent-resistant", "disorganized" ], "question_id": "fs-idp19520736", "question_text": "The child uses the parent as a base from which to explore her world in which attachment style?" }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 3, "ans_text": "by 25 years old" }, "bloom": null, "hl_context": "<hl> The adolescent brain also remains under development . <hl> Up until puberty , brain cells continue to bloom in the frontal region . Adolescents engage in increased risk-taking behaviors and emotional outbursts possibly because the frontal lobes of their brains are still developing ( Figure 9.16 ) . Recall that this area is responsible for judgment , impulse control , and planning , and it is still maturing into early adulthood ( Casey , Tottenham , Liston , & Durston , 2005 ) . <hl> The size of our brains increases rapidly . <hl> For example , the brain of a 2 - year-old is 55 % of its adult size , and by 6 years old the brain is about 90 % of its adult size ( Tanner , 1978 ) . <hl> During early childhood ( ages 3 – 6 ) , the frontal lobes grow rapidly . <hl> <hl> Recalling our discussion of the 4 lobes of the brain earlier in this book , the frontal lobes are associated with planning , reasoning , memory , and impulse control . <hl> <hl> Therefore , by the time children reach school age , they are developmentally capable of controlling their attention and behavior . <hl> <hl> Through the elementary school years , the frontal , temporal , occipital , and parietal lobes all grow in size . <hl> The brain growth spurts experienced in childhood tend to follow Piaget ’ s sequence of cognitive development , so that significant changes in neural functioning account for cognitive advances ( Kolb & Whishaw , 2009 ; Overman , Bachevalier , Turner , & Peuster , 1992 ) .", "hl_sentences": "The adolescent brain also remains under development . The size of our brains increases rapidly . During early childhood ( ages 3 – 6 ) , the frontal lobes grow rapidly . Recalling our discussion of the 4 lobes of the brain earlier in this book , the frontal lobes are associated with planning , reasoning , memory , and impulse control . Therefore , by the time children reach school age , they are developmentally capable of controlling their attention and behavior . Through the elementary school years , the frontal , temporal , occipital , and parietal lobes all grow in size .", "question": { "cloze_format": "The frontal lobes become fully developed ________.", "normal_format": "When do frontal lobes become fully developed?", "question_choices": [ "at birth", "at the beginning of adolescence", "at the end of adolescence", "by 25 years old" ], "question_id": "fs-idm70454672", "question_text": "The frontal lobes become fully developed ________." }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 1, "ans_text": "Cicely Saunders" }, "bloom": null, "hl_context": "Every story has an ending . Death marks the end of your life story ( Figure 9.21 ) . Our culture and individual backgrounds influence how we view death . In some cultures , death is accepted as a natural part of life and is embraced . In contrast , until about 50 years ago in the United States , a doctor might not inform someone that they were dying , and the majority of deaths occurred in hospitals . <hl> In 1967 that reality began to change with Cicely Saunders , who created the first modern hospice in England . <hl> The aim of hospice is to help provide a death with dignity and pain management in a humane and comfortable environment , which is usually outside of a hospital setting . In 1974 , Florence Wald founded the first hospice in the United States . Today , hospice provides care for 1.65 million Americans and their families . Because of hospice care , many terminally ill people are able to spend their last days at home .", "hl_sentences": "In 1967 that reality began to change with Cicely Saunders , who created the first modern hospice in England .", "question": { "cloze_format": "____ created the very first modern hospice.", "normal_format": "Who created the very first modern hospice?", "question_choices": [ "Elizabeth Kübler-Ross", "Cicely Saunders", "Florence Wald", "Florence Nightingale" ], "question_id": "fs-idp45427200", "question_text": "Who created the very first modern hospice?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 2, "ans_text": "denial, anger, bargaining, depression, acceptance" }, "bloom": null, "hl_context": "How do you think you might react if you were diagnosed with a terminal illness like cancer ? Elizabeth Kübler-Ross ( 1969 ) , who worked with the founders of hospice care , described the process of an individual accepting his own death . <hl> She proposed five stages of grief : denial , anger , bargaining , depression , and acceptance . <hl> Most individuals experience these stages , but the stages may occur in different orders , depending on the individual . In addition , not all people experience all of the stages . It is also important to note that some psychologists believe that the more a dying person fights death , the more likely he is to remain stuck in the denial phase . This could make it difficult for the dying person to face death with dignity . However , other psychologists believe that not facing death until the very end is an adaptive coping mechanism for some people .", "hl_sentences": "She proposed five stages of grief : denial , anger , bargaining , depression , and acceptance .", "question": { "cloze_format": "___ is the order of stages in Kübler-Ross's five-stage model of grief.", "normal_format": "Which of the following is the order of stages in Kübler-Ross’s five-stage model of grief?", "question_choices": [ "denial, bargaining, anger, depression, acceptance", "anger, depression, bargaining, acceptance, denial", "denial, anger, bargaining, depression, acceptance", "anger, acceptance, denial, depression, bargaining" ], "question_id": "fs-idp4726576", "question_text": "Which of the following is the order of stages in Kübler-Ross’s five-stage model of grief?" }, "references_are_paraphrase": null } ]
9
9.1 What Is Lifespan Development? Learning Objectives By the end of this section, you will be able to: Define and distinguish between the three domains of development: physical, cognitive and psychosocial Discuss the normative approach to development Understand the three major issues in development: continuity and discontinuity, one common course of development or many unique courses of development, and nature versus nurture My heart leaps up when I behold A rainbow in the sky: So was it when my life began; So is it now I am a man; So be it when I shall grow old, Or let me die! The Child is father of the Man; I could wish my days to be Bound each to each by natural piety. (Wordsworth, 1802) In this poem, William Wordsworth writes, “the child is father of the man.” What does this seemingly incongruous statement mean, and what does it have to do with lifespan development? Wordsworth might be suggesting that the person he is as an adult depends largely on the experiences he had in childhood. Consider the following questions: To what extent is the adult you are today influenced by the child you once were? To what extent is a child fundamentally different from the adult he grows up to be? These are the types of questions developmental psychologists try to answer, by studying how humans change and grow from conception through childhood, adolescence, adulthood, and death. They view development as a lifelong process that can be studied scientifically across three developmental domains—physical, cognitive, and psychosocial development. Physical development involves growth and changes in the body and brain, the senses, motor skills, and health and wellness. Cognitive development involves learning, attention, memory, language, thinking, reasoning, and creativity. Psychosocial development involves emotions, personality, and social relationships. We refer to these domains throughout the chapter. Connect the Concepts Research Methods in Developmental Psychology You’ve learned about a variety of research methods used by psychologists. Developmental psychologists use many of these approaches in order to better understand how individuals change mentally and physically over time. These methods include naturalistic observations, case studies, surveys, and experiments, among others. Naturalistic observations involve observing behavior in its natural context. A developmental psychologist might observe how children behave on a playground, at a daycare center, or in the child’s own home. While this research approach provides a glimpse into how children behave in their natural settings, researchers have very little control over the types and/or frequencies of displayed behavior. In a case study, developmental psychologists collect a great deal of information from one individual in order to better understand physical and psychological changes over the lifespan. This particular approach is an excellent way to better understand individuals, who are exceptional in some way, but it is especially prone to researcher bias in interpretation, and it is difficult to generalize conclusions to the larger population. In one classic example of this research method being applied to a study of lifespan development Sigmund Freud analyzed the development of a child known as “Little Hans” (Freud, 1909/1949). Freud’s findings helped inform his theories of psychosexual development in children, which you will learn about later in this chapter. Little Genie, the subject of a case study discussed in the chapter on thinking and intelligence, provides another example of how psychologists examine developmental milestones through detailed research on a single individual. In Genie’s case, her neglectful and abusive upbringing led to her being unable to speak until, at age 13, she was removed from that harmful environment. As she learned to use language, psychologists were able to compare how her language acquisition abilities differed when occurring in her late-stage development compared to the typical acquisition of those skills during the ages of infancy through early childhood (Fromkin, Krashen, Curtiss, Rigler, & Rigler, 1974; Curtiss, 1981). The survey method asks individuals to self-report important information about their thoughts, experiences, and beliefs. This particular method can provide large amounts of information in relatively short amounts of time; however, validity of data collected in this way relies on honest self-reporting, and the data is relatively shallow when compared to the depth of information collected in a case study. An example of comprehensive survey was the research done by Ruth W. Howard. In 1947, she obtained her doctorate by surveying 229 sets of triplets, the most comprehensive research of triplets completed at the time. This pioneering woman was also the first African-American woman to earn a PhD in psychology (American Psychological Association, 2019). Experiments involve significant control over extraneous variables and manipulation of the independent variable. As such, experimental research allows developmental psychologists to make causal statements about certain variables that are important for the developmental process. Because experimental research must occur in a controlled environment, researchers must be cautious about whether behaviors observed in the laboratory translate to an individual’s natural environment. Later in this chapter, you will learn about several experiments in which toddlers and young children observe scenes or actions so that researchers can determine at what age specific cognitive abilities develop. For example, children may observe a quantity of liquid poured from a short, fat glass into a tall, skinny glass. As the experimenters question the children about what occurred, the subjects’ answers help psychologists understand at what age a child begins to comprehend that the volume of liquid remained the same although the shapes of the containers differs. Across these three domains—physical, cognitive, and psychosocial—the normative approach to development is also discussed. This approach asks, “What is normal development?” In the early decades of the 20th century, normative psychologists studied large numbers of children at various ages to determine norms (i.e., average ages) of when most children reach specific developmental milestones in each of the three domains (Gesell, 1933, 1939, 1940; Gesell & Ilg, 1946; Hall, 1904). Although children develop at slightly different rates, we can use these age-related averages as general guidelines to compare children with same-age peers to determine the approximate ages they should reach specific normative events called developmental milestones (e.g., crawling, walking, writing, dressing, naming colors, speaking in sentences, and starting puberty). Not all normative events are universal, meaning they are not experienced by all individuals across all cultures. Biological milestones, such as puberty, tend to be universal, but social milestones, such as the age when children begin formal schooling, are not necessarily universal; instead, they affect most individuals in a particular culture (Gesell & Ilg, 1946). For example, in developed countries children begin school around 5 or 6 years old, but in developing countries, like Nigeria, children often enter school at an advanced age, if at all (Huebler, 2005; United Nations Educational, Scientific, and Cultural Organization [UNESCO], 2013). To better understand the normative approach, imagine two new mothers, Louisa and Kimberly, who are close friends and have children around the same age. Louisa’s daughter is 14 months old, and Kimberly’s son is 12 months old. According to the normative approach, the average age a child starts to walk is 12 months. However, at 14 months Louisa’s daughter still isn’t walking. She tells Kimberly she is worried that something might be wrong with her baby. Kimberly is surprised because her son started walking when he was only 10 months old. Should Louisa be worried? Should she be concerned if her daughter is not walking by 15 months or 18 months? Link to Learning The Centers for Disease Control and Prevention (CDC) describes the developmental milestones for children from 2 months through 5 years old. After reviewing the information, take this quiz to see how well you recall what you’ve learned. If you are a parent with concerns about your child’s development, contact your pediatrician. Issues in Developmental Psychology There are many different theoretical approaches regarding human development. As we evaluate them in this chapter, recall that developmental psychology focuses on how people change, and keep in mind that all the approaches that we present in this chapter address questions of change: Is the change smooth or uneven (continuous versus discontinuous)? Is this pattern of change the same for everyone, or are there many different patterns of change (one course of development versus many courses)? How do genetics and environment interact to influence development (nature versus nurture)? Is Development Continuous or Discontinuous? Continuous development views development as a cumulative process, gradually improving on existing skills ( Figure 9.2 ). With this type of development, there is gradual change. Consider, for example, a child’s physical growth: adding inches to her height year by year. In contrast, theorists who view development as discontinuous believe that development takes place in unique stages: It occurs at specific times or ages. With this type of development, the change is more sudden, such as an infant’s ability to conceive object permanence. Is There One Course of Development or Many? Is development essentially the same, or universal, for all children (i.e., there is one course of development) or does development follow a different course for each child, depending on the child’s specific genetics and environment (i.e., there are many courses of development)? Do people across the world share more similarities or more differences in their development? How much do culture and genetics influence a child’s behavior? Stage theories hold that the sequence of development is universal. For example, in cross-cultural studies of language development, children from around the world reach language milestones in a similar sequence (Gleitman & Newport, 1995). Infants in all cultures coo before they babble. They begin babbling at about the same age and utter their first word around 12 months old. Yet we live in diverse contexts that have a unique effect on each of us. For example, researchers once believed that motor development follows one course for all children regardless of culture. However, child care practices vary by culture, and different practices have been found to accelerate or inhibit achievement of developmental milestones such as sitting, crawling, and walking (Karasik, Adolph, Tamis-LeMonda, & Bornstein, 2010). For instance, let’s look at the Aché society in Paraguay. They spend a significant amount of time foraging in forests. While foraging, Aché mothers carry their young children, rarely putting them down in order to protect them from getting hurt in the forest. Consequently, their children walk much later: They walk around 23–25 months old, in comparison to infants in Western cultures who begin to walk around 12 months old. However, as Aché children become older, they are allowed more freedom to move about, and by about age 9, their motor skills surpass those of U.S. children of the same age: Aché children are able to climb trees up to 25 feet tall and use machetes to chop their way through the forest (Kaplan & Dove, 1987). As you can see, our development is influenced by multiple contexts, so the timing of basic motor functions may vary across cultures. However, the functions themselves are present in all societies ( Figure 9.3 ). How Do Nature and Nurture Influence Development? Are we who we are because of nature (biology and genetics), or are we who we are because of nurture (our environment and culture)? This longstanding question is known in psychology as the nature versus nurture debate. It seeks to understand how our personalities and traits are the product of our genetic makeup and biological factors, and how they are shaped by our environment, including our parents, peers, and culture. For instance, why do biological children sometimes act like their parents—is it because of genetics or because of early childhood environment and what the child has learned from the parents? What about children who are adopted—are they more like their biological families or more like their adoptive families? And how can siblings from the same family be so different? We are all born with specific genetic traits inherited from our parents, such as eye color, height, and certain personality traits. Beyond our basic genotype, however, there is a deep interaction between our genes and our environment: Our unique experiences in our environment influence whether and how particular traits are expressed, and at the same time, our genes influence how we interact with our environment (Diamond, 2009; Lobo, 2008). This chapter will show that there is a reciprocal interaction between nature and nurture as they both shape who we become, but the debate continues as to the relative contributions of each. Dig Deeper The Achievement Gap: How Does Socioeconomic Status Affect Development? The achievement gap refers to the persistent difference in grades, test scores, and graduation rates that exist among students of different ethnicities, races, and—in certain subjects—sexes (Winerman, 2011). Research suggests that these achievement gaps are strongly influenced by differences in socioeconomic factors that exist among the families of these children. While the researchers acknowledge that programs aimed at reducing such socioeconomic discrepancies would likely aid in equalizing the aptitude and performance of children from different backgrounds, they recognize that such large-scale interventions would be difficult to achieve. Therefore, it is recommended that programs aimed at fostering aptitude and achievement among disadvantaged children may be the best option for dealing with issues related to academic achievement gaps (Duncan & Magnuson, 2005). Low-income children perform significantly more poorly than their middle- and high-income peers on a number of educational variables: They have significantly lower standardized test scores, graduation rates, and college entrance rates, and they have much higher school dropout rates. There have been attempts to correct the achievement gap through state and federal legislation, but what if the problems start before the children even enter school? Psychologists Betty Hart and Todd Risley (2006) spent their careers looking at early language ability and progression of children in various income levels. In one longitudinal study, they found that although all the parents in the study engaged and interacted with their children, middle- and high-income parents interacted with their children differently than low-income parents. After analyzing 1,300 hours of parent-child interactions, the researchers found that middle- and high-income parents talk to their children significantly more, starting when the children are infants. By 3 years old, high-income children knew almost double the number of words known by their low-income counterparts, and they had heard an estimated total of 30 million more words than the low-income counterparts (Hart & Risley, 2003). And the gaps only become more pronounced. Before entering kindergarten, high-income children score 60% higher on achievement tests than their low-income peers (Lee & Burkam, 2002). There are solutions to this problem. At the University of Chicago, experts are working with low-income families, visiting them at their homes, and encouraging them to speak more to their children on a daily and hourly basis. Other experts are designing preschools in which students from diverse economic backgrounds are placed in the same classroom. In this research, low-income children made significant gains in their language development, likely as a result of attending the specialized preschool (Schechter & Byeb, 2007). What other methods or interventions could be used to decrease the achievement gap? What types of activities could be implemented to help the children of your community or a neighboring community? 9.2 Lifespan Theories Learning Objectives By the end of this section, you will be able to: Discuss Freud’s theory of psychosexual development Describe the major tasks of child and adult psychosocial development according to Erikson Discuss Piaget’s view of cognitive development and apply the stages to understanding childhood cognition Describe Kohlberg’s theory of moral development There are many theories regarding how babies and children grow and develop into happy, healthy adults. We explore several of these theories in this section. Psychosexual Theory of Development Sigmund Freud (1856–1939) believed that personality develops during early childhood. For Freud, childhood experiences shape our personalities and behavior as adults. Freud viewed development as discontinuous; he believed that each of us must pass through a series of stages during childhood, and that if we lack proper nurturance and parenting during a stage, we may become stuck, or fixated, in that stage. Freud’s stages are called the stages of psychosexual development . According to Freud, children’s pleasure-seeking urges are focused on a different area of the body, called an erogenous zone, at each of the five stages of development: oral, anal, phallic, latency, and genital. While most of Freud’s ideas have not found support in modern research, we cannot discount the contributions that Freud has made to the field of psychology. Psychologists today dispute Freud's psychosexual stages as a legitimate explanation for how one's personality develops, but what we can take away from Freud’s theory is that personality is shaped, in some part, by experiences we have in childhood. These stages are discussed in detail in the chapter on personality. Psychosocial Theory of Development Erik Erikson (1902–1994) ( Figure 9.4 ), another stage theorist, took Freud’s theory and modified it as psychosocial theory. Erikson’s psychosocial development theory emphasizes the social nature of our development rather than its sexual nature. While Freud believed that personality is shaped only in childhood, Erikson proposed that personality development takes place all through the lifespan. Erikson suggested that how we interact with others is what affects our sense of self, or what he called the ego identity. Erikson proposed that we are motivated by a need to achieve competence in certain areas of our lives. According to psychosocial theory, we experience eight stages of development over our lifespan, from infancy through late adulthood. At each stage there is a conflict, or task, that we need to resolve. Successful completion of each developmental task results in a sense of competence and a healthy personality. Failure to master these tasks leads to feelings of inadequacy. According to Erikson (1963), trust is the basis of our development during infancy (birth to 12 months). Therefore, the primary task of this stage is trust versus mistrust. Infants are dependent upon their caregivers, so caregivers who are responsive and sensitive to their infant’s needs help their baby to develop a sense of trust; their baby will see the world as a safe, predictable place. Unresponsive caregivers who do not meet their baby’s needs can engender feelings of anxiety, fear, and mistrust; their baby may see the world as unpredictable. As toddlers (ages 1–3 years) begin to explore their world, they learn that they can control their actions and act on the environment to get results. They begin to show clear preferences for certain elements of the environment, such as food, toys, and clothing. A toddler’s main task is to resolve the issue of autonomy versus shame and doubt, by working to establish independence. This is the “me do it” stage. For example, we might observe a budding sense of autonomy in a 2-year-old child who wants to choose her clothes and dress herself. Although her outfits might not be appropriate for the situation, her input in such basic decisions has an effect on her sense of independence. If denied the opportunity to act on her environment, she may begin to doubt her abilities, which could lead to low self-esteem and feelings of shame. Once children reach the preschool stage (ages 3–6 years), they are capable of initiating activities and asserting control over their world through social interactions and play. According to Erikson, preschool children must resolve the task of initiative versus guilt. By learning to plan and achieve goals while interacting with others, preschool children can master this task. Those who do will develop self-confidence and feel a sense of purpose. Those who are unsuccessful at this stage—with their initiative misfiring or stifled—may develop feelings of guilt. How might over-controlling parents stifle a child’s initiative? During the elementary school stage (ages 6–12), children face the task of industry versus inferiority. Children begin to compare themselves to their peers to see how they measure up. They either develop a sense of pride and accomplishment in their schoolwork, sports, social activities, and family life, or they feel inferior and inadequate when they don’t measure up. What are some things parents and teachers can do to help children develop a sense of competence and a belief in themselves and their abilities? In adolescence (ages 12–18), children face the task of identity versus role confusion. According to Erikson, an adolescent’s main task is developing a sense of self. Adolescents struggle with questions such as “Who am I?” and “What do I want to do with my life?” Along the way, most adolescents try on many different selves to see which ones fit. Adolescents who are successful at this stage have a strong sense of identity and are able to remain true to their beliefs and values in the face of problems and other people’s perspectives. What happens to apathetic adolescents, who do not make a conscious search for identity, or those who are pressured to conform to their parents’ ideas for the future? These teens will have a weak sense of self and experience role confusion. They are unsure of their identity and confused about the future. People in early adulthood (i.e., 20s through early 40s) are concerned with intimacy versus isolation. After we have developed a sense of self in adolescence, we are ready to share our life with others. Erikson said that we must have a strong sense of self before developing intimate relationships with others. Adults who do not develop a positive self-concept in adolescence may experience feelings of loneliness and emotional isolation. When people reach their 40s, they enter the time known as middle adulthood, which extends to the mid-60s. The social task of middle adulthood is generativity versus stagnation. Generativity involves finding your life’s work and contributing to the development of others, through activities such as volunteering, mentoring, and raising children. Those who do not master this task may experience stagnation, having little connection with others and little interest in productivity and self-improvement. From the mid-60s to the end of life, we are in the period of development known as late adulthood. Erikson’s task at this stage is called integrity versus despair. He said that people in late adulthood reflect on their lives and feel either a sense of satisfaction or a sense of failure. People who feel proud of their accomplishments feel a sense of integrity, and they can look back on their lives with few regrets. However, people who are not successful at this stage may feel as if their life has been wasted. They focus on what “would have,” “should have,” and “could have” been. They face the end of their lives with feelings of bitterness, depression, and despair. Table 9.1 summarizes the stages of Erikson’s theory. Stage Age (years) Developmental Task Description 1 0–1 Trust vs. mistrust Trust (or mistrust) that basic needs, such as nourishment and affection, will be met 2 1–3 Autonomy vs. shame/doubt Develop a sense of independence in many tasks 3 3–6 Initiative vs. guilt Take initiative on some activities—may develop guilt when unsuccessful or boundaries overstepped 4 7–11 Industry vs. inferiority Develop self-confidence in abilities when competent or sense of inferiority when not 5 12–18 Identity vs. confusion Experiment with and develop identity and roles 6 19–29 Intimacy vs. isolation Establish intimacy and relationships with others 7 30–64 Generativity vs. stagnation Contribute to society and be part of a family 8 65– Integrity vs. despair Assess and make sense of life and meaning of contributions Table 9.1 Erikson’s Psychosocial Stages of Development Cognitive Theory of Development Jean Piaget (1896–1980) is another stage theorist who studied childhood development ( Figure 9.5 ). Instead of approaching development from a psychoanalytical or psychosocial perspective, Piaget focused on children’s cognitive growth. He believed that thinking is a central aspect of development and that children are naturally inquisitive. However, he said that children do not think and reason like adults (Piaget, 1930, 1932). His theory of cognitive development holds that our cognitive abilities develop through specific stages, which exemplifies the discontinuity approach to development. As we progress to a new stage, there is a distinct shift in how we think and reason. Piaget said that children develop schemata to help them understand the world. Schemata are concepts (mental models) that are used to help us categorize and interpret information. By the time children have reached adulthood, they have created schemata for almost everything. When children learn new information, they adjust their schemata through two processes: assimilation and accommodation. First, they assimilate new information or experiences in terms of their current schemata: assimilation is when they take in information that is comparable to what they already know. Accommodation describes when they change their schemata based on new information. This process continues as children interact with their environment. For example, 2-year-old Blake learned the schema for dogs because his family has a Labrador retriever. When Blake sees other dogs in his picture books, he says, “Look mommy, dog!” Thus, he has assimilated them into his schema for dogs. One day, Blake sees a sheep for the first time and says, “Look mommy, dog!” Having a basic schema that a dog is an animal with four legs and fur, Blake thinks all furry, four-legged creatures are dogs. When Blake’s mom tells him that the animal he sees is a sheep, not a dog, Blake must accommodate his schema for dogs to include more information based on his new experiences. Blake’s schema for dog was too broad, since not all furry, four-legged creatures are dogs. He now modifies his schema for dogs and forms a new one for sheep. Like Freud and Erikson, Piaget thought development unfolds in a series of stages approximately associated with age ranges. He proposed a theory of cognitive development that unfolds in four stages: sensorimotor, preoperational, concrete operational, and formal operational ( Table 9.2 ). Age (years) Stage Description Developmental issues 0–2 Sensorimotor World experienced through senses and actions Object permanence Stranger anxiety 2–6 Preoperational Use words and images to represent things, but lack logical reasoning Pretend play Egocentrism Language development 7–11 Concrete operational Understand concrete events and analogies logically; perform arithmetical operations Conservation Mathematical transformations 12– Formal operational Formal operations Utilize abstract reasoning Abstract logic Moral reasoning Table 9.2 Piaget’s Stages of Cognitive Development The first stage is the sensorimotor stage, which lasts from birth to about 2 years old. During this stage, children learn about the world through their senses and motor behavior. Young children put objects in their mouths to see if the items are edible, and once they can grasp objects, they may shake or bang them to see if they make sounds. Between 5 and 8 months old, the child develops object permanence , which is the understanding that even if something is out of sight, it still exists (Bogartz, Shinskey, & Schilling, 2000). According to Piaget, young infants do not remember an object after it has been removed from sight. Piaget studied infants’ reactions when a toy was first shown to an infant and then hidden under a blanket. Infants who had already developed object permanence would reach for the hidden toy, indicating that they knew it still existed, whereas infants who had not developed object permanence would appear confused. Link to Learning Please take a few minutes to view this brief video demonstrating different children’s ability to understand object permanence. In Piaget’s view, around the same time children develop object permanence, they also begin to exhibit stranger anxiety, which is a fear of unfamiliar people. Babies may demonstrate this by crying and turning away from a stranger, by clinging to a caregiver, or by attempting to reach their arms toward familiar faces such as parents. Stranger anxiety results when a child is unable to assimilate the stranger into an existing schema; therefore, she can’t predict what her experience with that stranger will be like, which results in a fear response. Piaget’s second stage is the preoperational stage , which is from approximately 2 to 7 years old. In this stage, children can use symbols to represent words, images, and ideas, which is why children in this stage engage in pretend play. A child’s arms might become airplane wings as he zooms around the room, or a child with a stick might become a brave knight with a sword. Children also begin to use language in the preoperational stage, but they cannot understand adult logic or mentally manipulate information (the term operational refers to logical manipulation of information, so children at this stage are considered to be pre -operational). Children’s logic is based on their own personal knowledge of the world so far, rather than on conventional knowledge. For example, dad gave a slice of pizza to 10-year-old Keiko and another slice to her 3-year-old brother, Kenny. Kenny’s pizza slice was cut into five pieces, so Kenny told his sister that he got more pizza than she did. Children in this stage cannot perform mental operations because they have not developed an understanding of conservation , which is the idea that even if you change the appearance of something, it is still equal in size as long as nothing has been removed or added. Link to Learning This video shows a 4.5-year-old boy in the preoperational stage as he responds to Piaget’s conservation tasks. During this stage, we also expect children to display egocentrism , which means that the child is not able to take the perspective of others. A child at this stage thinks that everyone sees, thinks, and feels just as they do. Let’s look at Kenny and Keiko again. Keiko’s birthday is coming up, so their mom takes Kenny to the toy store to choose a present for his sister. He selects an Iron Man action figure for her, thinking that if he likes the toy, his sister will too. An egocentric child is not able to infer the perspective of other people and instead attributes his own perspective. Link to Learning Piaget developed the Three-Mountain Task to determine the level of egocentrism displayed by children. Children view a 3-dimensional mountain scene from one viewpoint, and are asked what another person at a different viewpoint would see in the same scene. Watch the Three-Mountain Task in action in this short video from the University of Minnesota and the Science Museum of Minnesota. Piaget’s third stage is the concrete operational stage , which occurs from about 7 to 11 years old. In this stage, children can think logically about real (concrete) events; they have a firm grasp on the use of numbers and start to employ memory strategies. They can perform mathematical operations and understand transformations, such as addition is the opposite of subtraction, and multiplication is the opposite of division. In this stage, children also master the concept of conservation: Even if something changes shape, its mass, volume, and number stay the same. For example, if you pour water from a tall, thin glass to a short, fat glass, you still have the same amount of water. Remember Keiko and Kenny and the pizza? How did Keiko know that Kenny was wrong when he said that he had more pizza? Children in the concrete operational stage also understand the principle of reversibility , which means that objects can be changed and then returned back to their original form or condition. Take, for example, water that you poured into the short, fat glass: You can pour water from the fat glass back to the thin glass and still have the same amount (minus a couple of drops). The fourth, and last, stage in Piaget’s theory is the formal operational stage , which is from about age 11 to adulthood. Whereas children in the concrete operational stage are able to think logically only about concrete events, children in the formal operational stage can also deal with abstract ideas and hypothetical situations. Children in this stage can use abstract thinking to problem solve, look at alternative solutions, and test these solutions. In adolescence, a renewed egocentrism occurs. For example, a 15-year-old with a very small pimple on her face might think it is huge and incredibly visible, under the mistaken impression that others must share her perceptions. Beyond Formal Operational Thought As with other major contributors of theories of development, several of Piaget’s ideas have come under criticism based on the results of further research. For example, several contemporary studies support a model of development that is more continuous than Piaget’s discrete stages (Courage & Howe, 2002; Siegler, 2005, 2006). Many others suggest that children reach cognitive milestones earlier than Piaget describes (Baillargeon, 2004; de Hevia & Spelke, 2010). According to Piaget, the highest level of cognitive development is formal operational thought, which develops between 11 and 20 years old. However, many developmental psychologists disagree with Piaget, suggesting a fifth stage of cognitive development, known as the postformal stage (Basseches, 1984; Commons & Bresette, 2006; Sinnott, 1998). In postformal thinking, decisions are made based on situations and circumstances, and logic is integrated with emotion as adults develop principles that depend on contexts. One way that we can see the difference between an adult in postformal thought and an adolescent in formal operations is in terms of how they handle emotionally charged issues. It seems that once we reach adulthood our problem solving abilities change: As we attempt to solve problems, we tend to think more deeply about many areas of our lives, such as relationships, work, and politics (Labouvie-Vief & Diehl, 1999). Because of this, postformal thinkers are able to draw on past experiences to help them solve new problems. Problem-solving strategies using postformal thought vary, depending on the situation. What does this mean? Adults can recognize, for example, that what seems to be an ideal solution to a problem at work involving a disagreement with a colleague may not be the best solution to a disagreement with a significant other. Theory of Moral Development A major task beginning in childhood and continuing into adolescence is discerning right from wrong. Psychologist Lawrence Kohlberg (1927–1987) extended upon the foundation that Piaget built regarding cognitive development. Kohlberg believed that moral development, like cognitive development, follows a series of stages. To develop this theory, Kohlberg posed moral dilemmas to people of all ages, and then he analyzed their answers to find evidence of their particular stage of moral development. Before reading about the stages, take a minute to consider how you would answer one of Kohlberg's best-known moral dilemmas, commonly known as the Heinz dilemma: In Europe, a woman was near death from a special kind of cancer. There was one drug that the doctors thought might save her. It was a form of radium that a druggist in the same town had recently discovered. The drug was expensive to make, but the druggist was charging ten times what the drug cost him to make. He paid $200 for the radium and charged $2,000 for a small dose of the drug. The sick woman's husband, Heinz, went to everyone he knew to borrow the money, but he could only get together about $1,000, which is half of what it cost. He told the druggist that his wife was dying and asked him to sell it cheaper or let him pay later. But the druggist said: “No, I discovered the drug and I'm going to make money from it.” So Heinz got desperate and broke into the man's store to steal the drug for his wife. Should the husband have done that? (Kohlberg, 1969, p. 379) How would you answer this dilemma? Kohlberg was not interested in whether you answer yes or no to the dilemma: Instead, he was interested in the reasoning behind your answer. After presenting people with this and various other moral dilemmas, Kohlberg reviewed people’s responses and placed them in different stages of moral reasoning ( Figure 9.6 ). According to Kohlberg, an individual progresses from the capacity for pre-conventional morality (before age 9) to the capacity for conventional morality (early adolescence), and toward attaining post-conventional morality (once formal operational thought is attained), which only a few fully achieve. Kohlberg placed in the highest stage responses that reflected the reasoning that Heinz should steal the drug because his wife’s life is more important than the pharmacist making money. The value of a human life overrides the pharmacist’s greed. It is important to realize that even those people who have the most sophisticated, post-conventional reasons for some choices may make other choices for the simplest of pre-conventional reasons. Many psychologists agree with Kohlberg's theory of moral development but point out that moral reasoning is very different from moral behavior. Sometimes what we say we would do in a situation is not what we actually do in that situation. In other words, we might “talk the talk,” but not “walk the walk.” How does this theory apply to males and females? Kohlberg (1969) felt that more males than females move past stage four in their moral development. He went on to note that women seem to be deficient in their moral reasoning abilities. These ideas were not well received by Carol Gilligan, a research assistant of Kohlberg, who consequently developed her own ideas of moral development. In her groundbreaking book, In a Different Voice: Psychological Theory and Women’s Development , Gilligan (1982) criticized her former mentor’s theory because it was based only on upper class White men and boys. She argued that women are not deficient in their moral reasoning—she proposed that males and females reason differently. Girls and women focus more on staying connected and the importance of interpersonal relationships. Therefore, in the Heinz dilemma, many girls and women respond that Heinz should not steal the medicine. Their reasoning is that if he steals the medicine, is arrested, and is put in jail, then he and his wife will be separated, and she could die while he is still in prison. 9.3 Stages of Development Learning Objectives By the end of this section, you will be able to: Describe the stages of prenatal development and recognize the importance of prenatal care Discuss physical, cognitive, and emotional development that occurs from infancy through childhood Discuss physical, cognitive, and emotional development that occurs during adolescence Discuss physical, cognitive, and emotional development that occurs in adulthood From the moment we are born until the moment we die, we continue to develop. As discussed at the beginning of this chapter, developmental psychologists often divide our development into three areas: physical development, cognitive development, and psychosocial development. Mirroring Erikson’s stages, lifespan development is divided into different stages that are based on age. We will discuss prenatal, infant, child, adolescent, and adult development. Prenatal Development How did you come to be who you are? From beginning as a one-cell structure to your birth, your prenatal development occurred in an orderly and delicate sequence. There are three stages of prenatal development: germinal, embryonic, and fetal. Let’s take a look at what happens to the developing baby in each of these stages. Germinal Stage (Weeks 1–2) In the discussion of biopsychology earlier in the book, you learned about genetics and DNA. A mother and father’s DNA is passed on to the child at the moment of conception. Conception occurs when sperm fertilizes an egg and forms a zygote ( Figure 9.7 ). A zygote begins as a one-cell structure that is created when a sperm and egg merge. The genetic makeup and sex of the baby are set at this point. During the first week after conception, the zygote divides and multiplies, going from a one-cell structure to two cells, then four cells, then eight cells, and so on. This process of cell division is called mitosis . Mitosis is a fragile process, and fewer than one-half of all zygotes survive beyond the first two weeks (Hall, 2004). After 5 days of mitosis there are 100 cells, and after 9 months there are billions of cells. As the cells divide, they become more specialized, forming different organs and body parts. In the germinal stage, the mass of cells has yet to attach itself to the lining of the mother’s uterus. Once it does, the next stage begins. Embryonic Stage (Weeks 3–8) After the zygote divides for about 7–10 days and has 150 cells, it travels down the fallopian tubes and implants itself in the lining of the uterus. Upon implantation, this multi-cellular organism is called an embryo . Now blood vessels grow, forming the placenta. The placenta is a structure connected to the uterus that provides nourishment and oxygen from the mother to the developing embryo via the umbilical cord. Basic structures of the embryo start to develop into areas that will become the head, chest, and abdomen. During the embryonic stage, the heart begins to beat and organs form and begin to function. The neural tube forms along the back of the embryo, developing into the spinal cord and brain. Fetal Stage (Weeks 9–40) When the organism is about nine weeks old, the embryo is called a fetus. At this stage, the fetus is about the size of a kidney bean and begins to take on the recognizable form of a human being as the “tail” begins to disappear. From 9–12 weeks, the sex organs begin to differentiate. At about 16 weeks, the fetus is approximately 4.5 inches long. Fingers and toes are fully developed, and fingerprints are visible. By the time the fetus reaches the sixth month of development (24 weeks), it weighs up to 1.4 pounds. Hearing has developed, so the fetus can respond to sounds. The internal organs, such as the lungs, heart, stomach, and intestines, have formed enough that a fetus born prematurely at this point has a chance to survive outside of the mother’s womb. Throughout the fetal stage the brain continues to grow and develop, nearly doubling in size from weeks 16 to 28. Around 36 weeks, the fetus is almost ready for birth. It weighs about 6 pounds and is about 18.5 inches long, and by week 37 all of the fetus’s organ systems are developed enough that it could survive outside the mother’s uterus without many of the risks associated with premature birth. The fetus continues to gain weight and grow in length until approximately 40 weeks. By then, the fetus has very little room to move around and birth becomes imminent. The progression through the stages is shown in Figure 9.8 . Link to Learning For an amazing look at prenatal development and the process of birth, view the video Life’s Greatest Miracle from Nova and PBS. Prenatal Influences During each prenatal stage, genetic and environmental factors can affect development. The developing fetus is completely dependent on the mother for life. It is important that the mother takes good care of herself and receives prenatal care , which is medical care during pregnancy that monitors the health of both the mother and the fetus ( Figure 9.9 ). According to the National Institutes of Health ([NIH], 2013), routine prenatal care is important because it can reduce the risk of complications to the mother and fetus during pregnancy. In fact, women who are trying to become pregnant or who may become pregnant should discuss pregnancy planning with their doctor. They may be advised, for example, to take a vitamin containing folic acid, which helps prevent certain birth defects, or to monitor aspects of their diet or exercise routines. Recall that when the zygote attaches to the wall of the mother’s uterus, the placenta is formed. The placenta provides nourishment and oxygen to the fetus. Most everything the mother ingests, including food, liquid, and even medication, travels through the placenta to the fetus, hence the common phrase “eating for two.” Anything the mother is exposed to in the environment affects the fetus; if the mother is exposed to something harmful, the child can show life-long effects. A teratogen is any environmental agent—biological, chemical, or physical—that causes damage to the developing embryo or fetus. There are different types of teratogens. Alcohol and most drugs cross the placenta and affect the fetus. Alcohol is not safe to drink in any amount during pregnancy. Alcohol use during pregnancy has been found to be the leading preventable cause of mental retardation in children in the United States (Maier & West, 2001). Excessive maternal drinking while pregnant can cause fetal alcohol spectrum disorders with life-long consequences for the child ranging in severity from minor to major ( Table 9.3 ). Fetal alcohol spectrum disorders (FASD) are a collection of birth defects associated with heavy consumption of alcohol during pregnancy. Physically, children with FASD may have a small head size and abnormal facial features. Cognitively, these children may have poor judgment, poor impulse control, higher rates of ADHD, learning issues, and lower IQ scores. These developmental problems and delays persist into adulthood (Streissguth et al., 2004). Based on studies conducted on animals, it also has been suggested that a mother’s alcohol consumption during pregnancy may predispose her child to like alcohol (Youngentob et al., 2007). Facial Feature Potential Effect of Fetal Alcohol Syndrome Head size Below-average head circumference Eyes Smaller than average eye opening, skin folds at corners of eyes Nose Low nasal bridge, short nose Midface Smaller than average midface size Lip and philtrum Thin upper lip, indistinct philtrum Table 9.3 Fetal Alcohol Syndrome Facial Features Smoking is also considered a teratogen because nicotine travels through the placenta to the fetus. When the mother smokes, the developing baby experiences a reduction in blood oxygen levels. According to the Centers for Disease Control and Prevention (2013), smoking while pregnant can result in premature birth, low-birth-weight infants, stillbirth, and sudden infant death syndrome (SIDS). Heroin, cocaine, methamphetamine, almost all prescription medicines, and most over-the counter medications are also considered teratogens. Babies born with a heroin addiction need heroin just like an adult addict. The child will need to be gradually weaned from the heroin under medical supervision; otherwise, the child could have seizures and die. Other teratogens include radiation, viruses such as HIV and herpes, and rubella (German measles). Women in the United States are much less likely to be afflicted with rubella because most women received childhood immunizations or vaccinations that protect the body from disease. Each organ of the fetus develops during a specific period in the pregnancy, called the critical or sensitive period ( Figure 9.8 ). For example, research with primate models of FASD has demonstrated that the time during which a developing fetus is exposed to alcohol can dramatically affect the appearance of facial characteristics associated with fetal alcohol syndrome. Specifically, this research suggests that alcohol exposure that is limited to day 19 or 20 of gestation can lead to significant facial abnormalities in the offspring (Ashley, Magnuson, Omnell, & Clarren, 1999). Given regions of the brain also show sensitive periods during which they are most susceptible to the teratogenic effects of alcohol (Tran & Kelly, 2003). What Do You Think? Should Women Who Use Drugs During Pregnancy Be Arrested and Jailed? As you now know, women who use drugs or alcohol during pregnancy can cause serious lifelong harm to their child. Some people have advocated mandatory screenings for women who are pregnant and have a history of drug abuse, and if the women continue using, to arrest, prosecute, and incarcerate them (Figdor & Kaeser, 1998). This policy was tried in Charleston, South Carolina, as recently as 20 years ago. The policy was called the Interagency Policy on Management of Substance Abuse During Pregnancy, and had disastrous results. The Interagency Policy applied to patients attending the obstetrics clinic at MUSC, which primarily serves patients who are indigent or on Medicaid. It did not apply to private obstetrical patients. The policy required patient education about the harmful effects of substance abuse during pregnancy. . . . [A] statement also warned patients that protection of unborn and newborn children from the harms of illegal drug abuse could involve the Charleston police, the Solicitor of the Ninth Judicial Court, and the Protective Services Division of the Department of Social Services (DSS). (Jos, Marshall, & Perlmutter, 1995, pp. 120–121) This policy seemed to deter women from seeking prenatal care, deterred them from seeking other social services, and was applied solely to low-income women, resulting in lawsuits. The program was canceled after 5 years, during which 42 women were arrested. A federal agency later determined that the program involved human experimentation without the approval and oversight of an institutional review board (IRB). What were the flaws in the program and how would you correct them? What are the ethical implications of charging pregnant women with child abuse? Infancy Through Childhood The average newborn weighs approximately 7.5 pounds. Although small, a newborn is not completely helpless because his reflexes and sensory capacities help him interact with the environment from the moment of birth. All healthy babies are born with newborn reflexes : inborn automatic responses to particular forms of stimulation. Reflexes help the newborn survive until it is capable of more complex behaviors—these reflexes are crucial to survival. They are present in babies whose brains are developing normally and usually disappear around 4–5 months old. Let’s take a look at some of these newborn reflexes. The rooting reflex is the newborn’s response to anything that touches her cheek: When you stroke a baby’s cheek, she naturally turns her head in that direction and begins to suck. The sucking reflex is the automatic, unlearned, sucking motions that infants do with their mouths. Several other interesting newborn reflexes can be observed. For instance, if you put your finger into a newborn’s hand, you will witness the grasping reflex, in which a baby automatically grasps anything that touches his palms. The Moro reflex is the newborn’s response when she feels like she is falling. The baby spreads her arms, pulls them back in, and then (usually) cries. How do you think these reflexes promote survival in the first months of life? Link to Learning Take a few minutes to view this brief video clip illustrating several newborn reflexes. What can young infants see, hear, and smell? Newborn infants’ sensory abilities are significant, but their senses are not yet fully developed. Many of a newborn’s innate preferences facilitate interaction with caregivers and other humans. Although vision is their least developed sense, newborns already show a preference for faces. Babies who are just a few days old also prefer human voices, they will listen to voices longer than sounds that do not involve speech (Vouloumanos & Werker, 2004), and they seem to prefer their mother’s voice over a stranger’s voice (Mills & Melhuish, 1974). In an interesting experiment, 3-week-old babies were given pacifiers that played a recording of the infant’s mother’s voice and of a stranger’s voice. When the infants heard their mother’s voice, they sucked more strongly at the pacifier (Mills & Melhuish, 1974). Newborns also have a strong sense of smell. For instance, newborn babies can distinguish the smell of their own mother from that of others. In a study by MacFarlane (1978), 1-week-old babies who were being breastfed were placed between two gauze pads. One gauze pad was from the bra of a nursing mother who was a stranger, and the other gauze pad was from the bra of the infant’s own mother. More than two-thirds of the week-old babies turned toward the gauze pad with their mother’s scent. Physical Development In infancy, toddlerhood, and early childhood, the body’s physical development is rapid ( Figure 9.10 ). On average, newborns weigh between 5 and 10 pounds, and a newborn’s weight typically doubles in six months and triples in one year. By 2 years old the weight will have quadrupled, so we can expect that a 2 year old should weigh between 20 and 40 pounds. The average length of a newborn is 19.5 inches, increasing to 29.5 inches by 12 months and 34.4 inches by 2 years old (WHO Multicentre Growth Reference Study Group, 2006). During infancy and childhood, growth does not occur at a steady rate (Carel, Lahlou, Roger, & Chaussain, 2004). Growth slows between 4 and 6 years old: During this time children gain 5–7 pounds and grow about 2–3 inches per year. Once girls reach 8–9 years old, their growth rate outpaces that of boys due to a pubertal growth spurt. This growth spurt continues until around 12 years old, coinciding with the start of the menstrual cycle. By 10 years old, the average girl weighs 88 pounds, and the average boy weighs 85 pounds. We are born with all of the brain cells that we will ever have—about 100–200 billion neurons (nerve cells) whose function is to store and transmit information (Huttenlocher & Dabholkar, 1997). However, the nervous system continues to grow and develop. Each neural pathway forms thousands of new connections during infancy and toddlerhood. This period of rapid neural growth is called blooming. Neural pathways continue to develop through puberty. The blooming period of neural growth is then followed by a period of pruning, where neural connections are reduced. It is thought that pruning causes the brain to function more efficiently, allowing for mastery of more complex skills (Hutchinson, 2011). Blooming occurs during the first few years of life, and pruning continues through childhood and into adolescence in various areas of the brain. The size of our brains increases rapidly. For example, the brain of a 2-year-old is 55% of its adult size, and by 6 years old the brain is about 90% of its adult size (Tanner, 1978). During early childhood (ages 3–6), the frontal lobes grow rapidly. Recalling our discussion of the 4 lobes of the brain earlier in this book, the frontal lobes are associated with planning, reasoning, memory, and impulse control. Therefore, by the time children reach school age, they are developmentally capable of controlling their attention and behavior. Through the elementary school years, the frontal, temporal, occipital, and parietal lobes all grow in size. The brain growth spurts experienced in childhood tend to follow Piaget’s sequence of cognitive development, so that significant changes in neural functioning account for cognitive advances (Kolb & Whishaw, 2009; Overman, Bachevalier, Turner, & Peuster, 1992). Motor development occurs in an orderly sequence as infants move from reflexive reactions (e.g., sucking and rooting) to more advanced motor functioning. For instance, babies first learn to hold their heads up, then to sit with assistance, and then to sit unassisted, followed later by crawling and then walking. Motor skills refer to our ability to move our bodies and manipulate objects. Fine motor skills focus on the muscles in our fingers, toes, and eyes, and enable coordination of small actions (e.g., grasping a toy, writing with a pencil, and using a spoon). Gross motor skills focus on large muscle groups that control our arms and legs and involve larger movements (e.g., balancing, running, and jumping). As motor skills develop, there are certain developmental milestones that young children should achieve ( Table 9.4 ). For each milestone there is an average age, as well as a range of ages in which the milestone should be reached. An example of a developmental milestone is sitting. On average, most babies sit alone at 7 months old. Sitting involves both coordination and muscle strength, and 90% of babies achieve this milestone between 5 and 9 months old. In another example, babies on average are able to hold up their head at 6 weeks old, and 90% of babies achieve this between 3 weeks and 4 months old. If a baby is not holding up his head by 4 months old, he is showing a delay. If the child is displaying delays on several milestones, that is reason for concern, and the parent or caregiver should discuss this with the child’s pediatrician. Some developmental delays can be identified and addressed through early intervention. Age (years) Physical Personal/Social Language Cognitive 2 Kicks a ball; walks up and down stairs Plays alongside other children; copies adults Points to objects when named; puts 2–4 words together in a sentence Sorts shapes and colors; follows 2-step instructions 3 Climbs and runs; pedals tricycle Takes turns; expresses many emotions; dresses self Names familiar things; uses pronouns Plays make believe; works toys with parts (levers, handles) 4 Catches balls; uses scissors Prefers social play to solo play; knows likes and interests Knows songs and rhymes by memory Names colors and numbers; begins writing letters 5 Hops and swings; uses fork and spoon Distinguishes real from pretend; likes to please friends Speaks clearly; uses full sentences Counts to 10 or higher; prints some letters and copies basic shapes Table 9.4 Developmental Milestones, Ages 2–5 Years Cognitive Development In addition to rapid physical growth, young children also exhibit significant development of their cognitive abilities. Piaget thought that children’s ability to understand objects—such as learning that a rattle makes a noise when shaken—was a cognitive skill that develops slowly as a child matures and interacts with the environment. Today, developmental psychologists think Piaget was incorrect. Researchers have found that even very young children understand objects and how they work long before they have experience with those objects (Baillargeon, 1987; Baillargeon, Li, Gertner, & Wu, 2011). For example, children as young as 3 months old demonstrated knowledge of the properties of objects that they had only viewed and did not have prior experience with them. In one study, 3-month-old infants were shown a truck rolling down a track and behind a screen. The box, which appeared solid but was actually hollow, was placed next to the track. The truck rolled past the box as would be expected. Then the box was placed on the track to block the path of the truck. When the truck was rolled down the track this time, it continued unimpeded. The infants spent significantly more time looking at this impossible event ( Figure 9.11 ). Baillargeon (1987) concluded that they knew solid objects cannot pass through each other. Baillargeon’s findings suggest that very young children have an understanding of objects and how they work, which Piaget (1954) would have said is beyond their cognitive abilities due to their limited experiences in the world. Just as there are physical milestones that we expect children to reach, there are also cognitive milestones. It is helpful to be aware of these milestones as children gain new abilities to think, problem solve, and communicate. For example, infants shake their head “no” around 6–9 months, and they respond to verbal requests to do things like “wave bye-bye” or “blow a kiss” around 9–12 months. Remember Piaget’s ideas about object permanence? We can expect children to grasp the concept that objects continue to exist even when they are not in sight by around 8 months old. Because toddlers (i.e., 12–24 months old) have mastered object permanence, they enjoy games like hide and seek, and they realize that when someone leaves the room they will come back (Loop, 2013). Toddlers also point to pictures in books and look in appropriate places when you ask them to find objects. Preschool-age children (i.e., 3–5 years old) also make steady progress in cognitive development. Not only can they count, name colors, and tell you their name and age, but they can also make some decisions on their own, such as choosing an outfit to wear. Preschool-age children understand basic time concepts and sequencing (e.g., before and after), and they can predict what will happen next in a story. They also begin to enjoy the use of humor in stories. Because they can think symbolically, they enjoy pretend play and inventing elaborate characters and scenarios. One of the most common examples of their cognitive growth is their blossoming curiosity. Preschool-age children love to ask “Why?” An important cognitive change occurs in children this age. Recall that Piaget described 2–3 year olds as egocentric, meaning that they do not have an awareness of others’ points of view. Between 3 and 5 years old, children come to understand that people have thoughts, feelings, and beliefs that are different from their own. This is known as theory-of-mind (TOM). Children can use this skill to tease others, persuade their parents to purchase a candy bar, or understand why a sibling might be angry. When children develop TOM, they can recognize that others have false beliefs (Dennett, 1987; Callaghan et al., 2005). Link to Learning False-belief tasks are useful in determining a child’s acquisition of theory-of-mind (TOM). Take a look at this video clip showing a false-belief task involving a box of crayons. Cognitive skills continue to expand in middle and late childhood (6–11 years old). Thought processes become more logical and organized when dealing with concrete information ( Figure 9.12 ). Children at this age understand concepts such as the past, present, and future, giving them the ability to plan and work toward goals. Additionally, they can process complex ideas such as addition and subtraction and cause-and-effect relationships. However, children’s attention spans tend to be very limited until they are around 11 years old. After that point, it begins to improve through adulthood. One well-researched aspect of cognitive development is language acquisition. As mentioned earlier, the order in which children learn language structures is consistent across children and cultures (Hatch, 1983). You’ve also learned that some psychological researchers have proposed that children possess a biological predisposition for language acquisition. Starting before birth, babies begin to develop language and communication skills. At birth, babies apparently recognize their mother’s voice and can discriminate between the language(s) spoken by their mothers and foreign languages, and they show preferences for faces that are moving in synchrony with audible language (Blossom & Morgan, 2006; Pickens, 1994; Spelke & Cortelyou, 1981). Children communicate information through gesturing long before they speak, and there is some evidence that gesture usage predicts subsequent language development (Iverson & Goldin-Meadow, 2005). In terms of producing spoken language, babies begin to coo almost immediately. Cooing is a one-syllable combination of a consonant and a vowel sound (e.g., coo or ba). Interestingly, babies replicate sounds from their own languages. A baby whose parents speak French will coo in a different tone than a baby whose parents speak Spanish or Urdu. After cooing, the baby starts to babble. Babbling begins with repeating a syllable, such as ma-ma, da-da, or ba-ba. When a baby is about 12 months old, we expect her to say her first word for meaning, and to start combining words for meaning at about 18 months. At about 2 years old, a toddler uses between 50 and 200 words; by 3 years old they have a vocabulary of up to 1,000 words and can speak in sentences. During the early childhood years, children's vocabulary increases at a rapid pace. This is sometimes referred to as the “vocabulary spurt” and has been claimed to involve an expansion in vocabulary at a rate of 10–20 new words per week. Recent research may indicate that while some children experience these spurts, it is far from universal (as discussed in Ganger & Brent, 2004). It has been estimated that, 5 year olds understand about 6,000 words, speak 2,000 words, and can define words and question their meanings. They can rhyme and name the days of the week. Seven year olds speak fluently and use slang and clichés (Stork & Widdowson, 1974). What accounts for such dramatic language learning by children? Behaviorist B. F. Skinner thought that we learn language in response to reinforcement or feedback, such as through parental approval or through being understood. For example, when a two-year-old child asks for juice, he might say, “me juice,” to which his mother might respond by giving him a cup of apple juice. Noam Chomsky (1957) criticized Skinner’s theory and proposed that we are all born with an innate capacity to learn language. Chomsky called this mechanism a language acquisition device (LAD). Who is correct? Both Chomsky and Skinner are right. Remember that we are a product of both nature and nurture. Researchers now believe that language acquisition is partially inborn and partially learned through our interactions with our linguistic environment (Gleitman & Newport, 1995; Stork & Widdowson, 1974). Attachment Psychosocial development occurs as children form relationships, interact with others, and understand and manage their feelings. In social and emotional development, forming healthy attachments is very important and is the major social milestone of infancy. Attachment is a long-standing connection or bond with others. Developmental psychologists are interested in how infants reach this milestone. They ask such questions as: How do parent and infant attachment bonds form? How does neglect affect these bonds? What accounts for children’s attachment differences? Researchers Harry Harlow, John Bowlby, and Mary Ainsworth conducted studies designed to answer these questions. In the 1950s, Harlow conducted a series of experiments on monkeys. He separated newborn monkeys from their mothers. Each monkey was presented with two surrogate mothers. One surrogate monkey was made out of wire mesh, and she could dispense milk. The other monkey was softer and made from cloth: This monkey did not dispense milk. Research shows that the monkeys preferred the soft, cuddly cloth monkey, even though she did not provide any nourishment. The baby monkeys spent their time clinging to the cloth monkey and only went to the wire monkey when they needed to be fed. Prior to this study, the medical and scientific communities generally thought that babies become attached to the people who provide their nourishment. However, Harlow (1958) concluded that there was more to the mother-child bond than nourishment. Feelings of comfort and security are the critical components to maternal-infant bonding, which leads to healthy psychosocial development. Link to Learning Harlow’s studies of monkeys were performed before modern ethics guidelines were in place, and today his experiments are widely considered to be unethical and even cruel. Watch this video to see actual footage of Harlow’s monkey studies. Building on the work of Harlow and others, John Bowlby developed the concept of attachment theory. He defined attachment as the affectional bond or tie that an infant forms with the mother (Bowlby, 1969). An infant must form this bond with a primary caregiver in order to have normal social and emotional development. In addition, Bowlby proposed that this attachment bond is very powerful and continues throughout life. He used the concept of secure base to define a healthy attachment between parent and child (1988). A secure base is a parental presence that gives the child a sense of safety as he explores his surroundings. Bowlby said that two things are needed for a healthy attachment: The caregiver must be responsive to the child’s physical, social, and emotional needs; and the caregiver and child must engage in mutually enjoyable interactions (Bowlby, 1969) ( Figure 9.13 ). While Bowlby thought attachment was an all-or-nothing process, Mary Ainsworth’s (1970) research showed otherwise. Ainsworth wanted to know if children differ in the ways they bond, and if so, why. To find the answers, she used the Strange Situation procedure to study attachment between mothers and their infants (1970). In the Strange Situation, the mother (or primary caregiver) and the infant (age 12-18 months) are placed in a room together. There are toys in the room, and the caregiver and child spend some time alone in the room. After the child has had time to explore her surroundings, a stranger enters the room. The mother then leaves her baby with the stranger. After a few minutes, she returns to comfort her child. Based on how the infants/toddlers responded to the separation and reunion, Ainsworth identified three types of parent-child attachments: secure, avoidant, and resistant (Ainsworth & Bell, 1970). A fourth style, known as disorganized attachment, was later described (Main & Solomon, 1990). The most common type of attachment—also considered the healthiest—is called secure attachment ( Figure 9.14 ). In this type of attachment, the toddler prefers his parent over a stranger. The attachment figure is used as a secure base to explore the environment and is sought out in times of stress. Securely attached children were distressed when their caregivers left the room in the Strange Situation experiment, but when their caregivers returned, the securely attached children were happy to see them. Securely attached children have caregivers who are sensitive and responsive to their needs. With avoidant attachment , the child is unresponsive to the parent, does not use the parent as a secure base, and does not care if the parent leaves. The toddler reacts to the parent the same way she reacts to a stranger. When the parent does return, the child is slow to show a positive reaction. Ainsworth theorized that these children were most likely to have a caregiver who was insensitive and inattentive to their needs (Ainsworth, Blehar, Waters, & Wall, 1978). In cases of resistant attachment , children tend to show clingy behavior, but then they reject the attachment figure’s attempts to interact with them (Ainsworth & Bell, 1970). These children do not explore the toys in the room, as they are too fearful. During separation in the Strange Situation, they became extremely disturbed and angry with the parent. When the parent returns, the children are difficult to comfort. Resistant attachment is the result of the caregivers’ inconsistent level of response to their child. Finally, children with disorganized attachment behaved oddly in the Strange Situation. They freeze, run around the room in an erratic manner, or try to run away when the caregiver returns (Main & Solomon, 1990). This type of attachment is seen most often in kids who have been abused. Research has shown that abuse disrupts a child’s ability to regulate their emotions. While Ainsworth’s research has found support in subsequent studies, it has also met criticism. Some researchers have pointed out that a child’s temperament may have a strong influence on attachment (Gervai, 2009; Harris, 2009), and others have noted that attachment varies from culture to culture, a factor not accounted for in Ainsworth’s research (Rothbaum, Weisz, Pott, Miyake, & Morelli, 2000; van Ijzendoorn & Sagi-Schwartz, 2008). Link to Learning Watch this video to view a clip of the Strange Situation. Try to identify which type of attachment baby Lisa exhibits. Self-Concept Just as attachment is the main psychosocial milestone of infancy, the primary psychosocial milestone of childhood is the development of a positive sense of self. How does self-awareness develop? Infants don’t have a self-concept, which is an understanding of who they are. If you place a baby in front of a mirror, she will reach out to touch her image, thinking it is another baby. However, by about 18 months a toddler will recognize that the person in the mirror is herself. How do we know this? In a well-known experiment, a researcher placed a red dot of paint on children’s noses before putting them in front of a mirror (Amsterdam, 1972). Commonly known as the mirror test, this behavior is demonstrated by humans and a few other species and is considered evidence of self-recognition (Archer, 1992). At 18 months old they would touch their own noses when they saw the paint, surprised to see a spot on their faces. By 24–36 months old children can name and/or point to themselves in pictures, clearly indicating self-recognition. Children from 2–4 years old display a great increase in social behavior once they have established a self-concept. They enjoy playing with other children, but they have difficulty sharing their possessions. Also, through play children explore and come to understand their gender roles and can label themselves as a girl or boy (Chick, Heilman-Houser, & Hunter, 2002). By 4 years old, children can cooperate with other children, share when asked, and separate from parents with little anxiety. Children at this age also exhibit autonomy, initiate tasks, and carry out plans. Success in these areas contributes to a positive sense of self. Once children reach 6 years old, they can identify themselves in terms of group memberships: “I’m a first grader!” School-age children compare themselves to their peers and discover that they are competent in some areas and less so in others (recall Erikson’s task of industry versus inferiority). At this age, children recognize their own personality traits as well as some other traits they would like to have. For example, 10-year-old Layla says, “I’m kind of shy. I wish I could be more talkative like my friend Alexa.” Development of a positive self-concept is important to healthy development. Children with a positive self-concept tend to be more confident, do better in school, act more independently, and are more willing to try new activities (Maccoby, 1980; Ferrer & Fugate, 2003). Formation of a positive self-concept begins in Erikson’s toddlerhood stage, when children establish autonomy and become confident in their abilities. Development of self-concept continues in elementary school, when children compare themselves to others. When the comparison is favorable, children feel a sense of competence and are motivated to work harder and accomplish more. Self-concept is re-evaluated in Erikson’s adolescence stage, as teens form an identity. They internalize the messages they have received regarding their strengths and weaknesses, keeping some messages and rejecting others. Adolescents who have achieved identity formation are capable of contributing positively to society (Erikson, 1968). What can parents do to nurture a healthy self-concept? Diana Baumrind (1971, 1991) thinks parenting style may be a factor. The way we parent is an important factor in a child’s socioemotional growth. Baumrind developed and refined a theory describing four parenting styles: authoritative, authoritarian, permissive, and uninvolved. With the authoritative style , the parent gives reasonable demands and consistent limits, expresses warmth and affection, and listens to the child’s point of view. Parents set rules and explain the reasons behind them. They are also flexible and willing to make exceptions to the rules in certain cases—for example, temporarily relaxing bedtime rules to allow for a nighttime swim during a family vacation. Of the four parenting styles, the authoritative style is the one that is most encouraged in modern American society. American children raised by authoritative parents tend to have high self-esteem and social skills. However, effective parenting styles vary as a function of culture and, as Small (1999) points out, the authoritative style is not necessarily preferred or appropriate in all cultures. In authoritarian style , the parent places high value on conformity and obedience. The parents are often strict, tightly monitor their children, and express little warmth. In contrast to the authoritative style, authoritarian parents probably would not relax bedtime rules during a vacation because they consider the rules to be set, and they expect obedience. This style can create anxious, withdrawn, and unhappy kids. However, it is important to point out that authoritarian parenting is as beneficial as the authoritative style in some ethnic groups (Russell, Crockett, & Chao, 2010). For instance, first-generation Chinese American children raised by authoritarian parents did just as well in school as their peers who were raised by authoritative parents (Russell et al., 2010). For parents who employ the permissive style of parenting, the kids run the show and anything goes. Permissive parents make few demands and rarely use punishment. They tend to be very nurturing and loving, and may play the role of friend rather than parent. In terms of our example of vacation bedtimes, permissive parents might not have bedtime rules at all—instead they allow the child to choose his bedtime whether on vacation or not. Not surprisingly, children raised by permissive parents tend to lack self-discipline, and the permissive parenting style is negatively associated with grades (Dornbusch, Ritter, Leiderman, Roberts, & Fraleigh, 1987). The permissive style may also contribute to other risky behaviors such as alcohol abuse (Bahr & Hoffman, 2010), risky sexual behavior especially among female children (Donenberg, Wilson, Emerson, & Bryant, 2002), and increased display of disruptive behaviors by male children (Parent et al., 2011). However, there are some positive outcomes associated with children raised by permissive parents. They tend to have higher self-esteem, better social skills, and report lower levels of depression (Darling, 1999). With the uninvolved style of parenting, the parents are indifferent, uninvolved, and sometimes referred to as neglectful. They don’t respond to the child’s needs and make relatively few demands. This could be because of severe depression or substance abuse, or other factors such as the parents’ extreme focus on work. These parents may provide for the child’s basic needs, but little else. The children raised in this parenting style are usually emotionally withdrawn, fearful, anxious, perform poorly in school, and are at an increased risk of substance abuse (Darling, 1999). As you can see, parenting styles influence childhood adjustment, but could a child’s temperament likewise influence parenting? Temperament refers to innate traits that influence how one thinks, behaves, and reacts with the environment. Children with easy temperaments demonstrate positive emotions, adapt well to change, and are capable of regulating their emotions. Conversely, children with difficult temperaments demonstrate negative emotions and have difficulty adapting to change and regulating their emotions. Difficult children are much more likely to challenge parents, teachers, and other caregivers (Thomas, 1984). Therefore, it’s possible that easy children (i.e., social, adaptable, and easy to soothe) tend to elicit warm and responsive parenting, while demanding, irritable, withdrawn children evoke irritation in their parents or cause their parents to withdraw (Sanson & Rothbart, 1995). Everyday Connection The Importance of Play and Recess According to the American Academy of Pediatrics (2007), unstructured play is an integral part of a child’s development. It builds creativity, problem solving skills, and social relationships. Play also allows children to develop a theory-of-mind as they imaginatively take on the perspective of others. Outdoor play allows children the opportunity to directly experience and sense the world around them. While doing so, they may collect objects that they come across and develop lifelong interests and hobbies. They also benefit from increased exercise, and engaging in outdoor play can actually increase how much they enjoy physical activity. This helps support the development of a healthy heart and brain. Unfortunately, research suggests that today’s children are engaging in less and less outdoor play (Clements, 2004). Perhaps, it is no surprise to learn that lowered levels of physical activity in conjunction with easy access to calorie-dense foods with little nutritional value are contributing to alarming levels of childhood obesity (Karnik & Kanekar, 2012). Despite the adverse consequences associated with reduced play, some children are over scheduled and have little free time to engage in unstructured play. In addition, some schools have taken away recess time for children in a push for students to do better on standardized tests, and many schools commonly use loss of recess as a form of punishment. Do you agree with these practices? Why or why not? Adolescence Adolescence is a socially constructed concept. In pre-industrial society, children were considered adults when they reached physical maturity, but today we have an extended time between childhood and adulthood called adolescence. Adolescence is the period of development that begins at puberty and ends at emerging adulthood, which is discussed later. In the United States, adolescence is seen as a time to develop independence from parents while remaining connected to them ( Figure 9.15 ). The typical age range of adolescence is from 12 to 18 years, and this stage of development also has some predictable physical, cognitive, and psychosocial milestones. Physical Development As noted above, adolescence begins with puberty. While the sequence of physical changes in puberty is predictable, the onset and pace of puberty vary widely. Several physical changes occur during puberty, such as adrenarche and gonadarche , the maturing of the adrenal glands and sex glands, respectively. Also during this time, primary and secondary sexual characteristics develop and mature. Primary sexual characteristics are organs specifically needed for reproduction, like the uterus and ovaries in females and testes in males. Secondary sexual characteristics are physical signs of sexual maturation that do not directly involve sex organs, such as development of breasts and hips in girls, and development of facial hair and a deepened voice in boys. Girls experience menarche , the beginning of menstrual periods, usually around 12–13 years old, and boys experience spermarche , the first ejaculation, around 13–14 years old. During puberty, both sexes experience a rapid increase in height (i.e., growth spurt). For girls this begins between 8 and 13 years old, with adult height reached between 10 and 16 years old. Boys begin their growth spurt slightly later, usually between 10 and 16 years old, and reach their adult height between 13 and 17 years old. Both nature (i.e., genes) and nurture (e.g., nutrition, medications, and medical conditions) can influence height. Because rates of physical development vary so widely among teenagers, puberty can be a source of pride or embarrassment. Early maturing boys tend to be stronger, taller, and more athletic than their later maturing peers. They are usually more popular, confident, and independent, but they are also at a greater risk for substance abuse and early sexual activity (Flannery, Rowe, & Gulley, 1993; Kaltiala-Heino, Rimpela, Rissanen, & Rantanen, 2001). Early maturing girls may be teased or overtly admired, which can cause them to feel self-conscious about their developing bodies. These girls are at a higher risk for depression, substance abuse, and eating disorders (Ge, Conger, & Elder, 2001; Graber, Lewinsohn, Seeley, & Brooks-Gunn, 1997; Striegel-Moore & Cachelin, 1999). Late blooming boys and girls (i.e., they develop more slowly than their peers) may feel self-conscious about their lack of physical development. Negative feelings are particularly a problem for late maturing boys, who are at a higher risk for depression and conflict with parents (Graber et al., 1997) and more likely to be bullied (Pollack & Shuster, 2000). The adolescent brain also remains under development. Up until puberty, brain cells continue to bloom in the frontal region. Adolescents engage in increased risk-taking behaviors and emotional outbursts possibly because the frontal lobes of their brains are still developing ( Figure 9.16 ). Recall that this area is responsible for judgment, impulse control, and planning, and it is still maturing into early adulthood (Casey, Tottenham, Liston, & Durston, 2005). Link to Learning According to neuroscientist Jay Giedd in the Frontline video “Inside the Teenage Brain” (2013), “It’s sort of unfair to expect [teens] to have adult levels of organizational skills or decision-making before their brains are finished being built.” Watch this segment on “The Wiring of the Adolescent Brain” to find out more about the developing brain during adolescence. Cognitive Development More complex thinking abilities emerge during adolescence. Some researchers suggest this is due to increases in processing speed and efficiency rather than as the result of an increase in mental capacity—in other words, due to improvements in existing skills rather than development of new ones (Bjorkland, 1987; Case, 1985). During adolescence, teenagers move beyond concrete thinking and become capable of abstract thought. Recall that Piaget refers to this stage as formal operational thought. Teen thinking is also characterized by the ability to consider multiple points of view, imagine hypothetical situations, debate ideas and opinions (e.g., politics, religion, and justice), and form new ideas ( Figure 9.17 ). In addition, it’s not uncommon for adolescents to question authority or challenge established societal norms. Cognitive empathy , also known as theory-of-mind (which we discussed earlier with regard to egocentrism), relates to the ability to take the perspective of others and feel concern for others (Shamay-Tsoory, Tomer, & Aharon-Peretz, 2005). Cognitive empathy begins to increase in adolescence and is an important component of social problem solving and conflict avoidance. According to one longitudinal study, levels of cognitive empathy begin rising in girls around 13 years old, and around 15 years old in boys (Van der Graaff et al., 2013). Teens who reported having supportive fathers with whom they could discuss their worries were found to be better able to take the perspective of others (Miklikowska, Duriez, & Soenens, 2011). Psychosocial Development Adolescents continue to refine their sense of self as they relate to others. Erikson referred to the task of the adolescent as one of identity versus role confusion. Thus, in Erikson’s view, an adolescent’s main questions are “Who am I?” and “Who do I want to be?” Some adolescents adopt the values and roles that their parents expect for them. Other teens develop identities that are in opposition to their parents but align with a peer group. This is common as peer relationships become a central focus in adolescents’ lives. As adolescents work to form their identities, they pull away from their parents, and the peer group becomes very important (Shanahan, McHale, Osgood, & Crouter, 2007). Despite spending less time with their parents, most teens report positive feelings toward them (Moore, Guzman, Hair, Lippman, & Garrett, 2004). Warm and healthy parent-child relationships have been associated with positive child outcomes, such as better grades and fewer school behavior problems, in the United States as well as in other countries (Hair et al., 2005). It appears that most teens don’t experience adolescent storm and stress to the degree once famously suggested by G. Stanley Hall, a pioneer in the study of adolescent development. Only small numbers of teens have major conflicts with their parents (Steinberg & Morris, 2001), and most disagreements are minor. For example, in a study of over 1,800 parents of adolescents from various cultural and ethnic groups, Barber (1994) found that conflicts occurred over day-to-day issues such as homework, money, curfews, clothing, chores, and friends. These types of arguments tend to decrease as teens develop (Galambos & Almeida, 1992). Emerging Adulthood The next stage of development is emerging adulthood . This is a relatively newly defined period of lifespan development spanning from 18 years old to the mid-20s, characterized as an in-between time where identity exploration is focused on work and love. When does a person become an adult? There are many ways to answer this question. In the United States, you are legally considered an adult at 18 years old. But other definitions of adulthood vary widely; in sociology, for example, a person may be considered an adult when she becomes self-supporting, chooses a career, gets married, or starts a family. The ages at which we achieve these milestones vary from person to person as well as from culture to culture. For example, in the African country of Malawi, 15-year-old Njemile was married at 14 years old and had her first child at 15 years old. In her culture she is considered an adult. Children in Malawi take on adult responsibilities such as marriage and work (e.g., carrying water, tending babies, and working fields) as early as 10 years old. In stark contrast, independence in Western cultures is taking longer and longer, effectively delaying the onset of adult life. Why is it taking twentysomethings so long to grow up? It seems that emerging adulthood is a product of both Western culture and our current times (Arnett, 2000). People in developed countries are living longer, allowing the freedom to take an extra decade to start a career and family. Changes in the workforce also play a role. For example, 50 years ago, a young adult with a high school diploma could immediately enter the work force and climb the corporate ladder. That is no longer the case. Bachelor’s and even graduate degrees are required more and more often—even for entry-level jobs (Arnett, 2000). In addition, many students are taking longer (five or six years) to complete a college degree as a result of working and going to school at the same time. After graduation, many young adults return to the family home because they have difficulty finding a job. Changing cultural expectations may be the most important reason for the delay in entering adult roles. Young people are spending more time exploring their options, so they are delaying marriage and work as they change majors and jobs multiple times, putting them on a much later timetable than their parents (Arnett, 2000). Adulthood Adulthood begins around 20 years old and has three distinct stages: early, middle, and late. Each stage brings its own set of rewards and challenges. Physical Development By the time we reach early adulthood (20 to early 40s), our physical maturation is complete, although our height and weight may increase slightly. In young adulthood, our physical abilities are at their peak, including muscle strength, reaction time, sensory abilities, and cardiac functioning. Most professional athletes are at the top of their game during this stage. Many women have children in the young adulthood years, so they may see additional weight gain and breast changes. Middle adulthood extends from the 40s to the 60s ( Figure 9.18 ). Physical decline is gradual. The skin loses some elasticity, and wrinkles are among the first signs of aging. Visual acuity decreases during this time. Women experience a gradual decline in fertility as they approach the onset of menopause, the end of the menstrual cycle, around 50 years old. Both men and women tend to gain weight: in the abdominal area for men and in the hips and thighs for women. Hair begins to thin and turn gray. Late adulthood is considered to extend from the 60s on. This is the last stage of physical change. The skin continues to lose elasticity, reaction time slows further, and muscle strength diminishes. Smell, taste, hearing, and vision, so sharp in our twenties, decline significantly. The brain may also no longer function at optimal levels, leading to problems like memory loss, dementia, and Alzheimer’s disease in later years. Link to Learning Aging doesn’t mean a person can’t explore new pursuits, learn new skills, and continue to grow. Watch this inspiring story about Neil Unger who is a newbie to the world of skateboarding at 60 years old. Cognitive Development Because we spend so many years in adulthood (more than any other stage), cognitive changes are numerous. In fact, research suggests that adult cognitive development is a complex, ever changing process that may be even more active than cognitive development in infancy and early childhood (Fischer, Yan, & Stewart, 2003). Link to Learning There is good news for the middle age brain. View this brief video to find out what it is. Unlike our physical abilities, which peak in our mid-20s and then begin a slow decline, our cognitive abilities remain steady throughout early and middle adulthood. Our crystalized intelligence (information, skills, and strategies we have gathered through a lifetime of experience) tends to hold steady as we age—it may even improve. For example, adults show relatively stable to increasing scores on intelligence tests until their mid-30s to mid-50s (Bayley & Oden, 1955). However, in late adulthood we begin to experience a decline in another area of our cognitive abilities—fluid intelligence (information processing abilities, reasoning, and memory). These processes become slower. How can we delay the onset of cognitive decline? Mental and physical activity seems to play a part ( Figure 9.19 ). Research has found adults who engage in mentally and physically stimulating activities experience less cognitive decline and have a reduced incidence of mild cognitive impairment and dementia (Hertzog, Kramer, Wilson, & Lindenberger, 2009; Larson et al., 2006; Podewils et al., 2005). Psychosocial Development There are many theories about the social and emotional aspects of aging. Some aspects of healthy aging include activities, social connectedness, and the role of a person’s culture. According to many theorists, including George Vaillant (2002), who studied and analyzed over 50 years of data, we need to have and continue to find meaning throughout our lives. For those in early and middle adulthood, meaning is found through work (Sterns & Huyck, 2001) and family life (Markus, Ryff, Curan, & Palmersheim, 2004). These areas relate to the tasks that Erikson referred to as generativity and intimacy. As mentioned previously, adults tend to define themselves by what they do—their careers. Earnings peak during this time, yet job satisfaction is more closely tied to work that involves contact with other people, is interesting, provides opportunities for advancement, and allows some independence (Mohr & Zoghi, 2006) than it is to salary (Iyengar, Wells, & Schwartz, 2006). How might being unemployed or being in a dead-end job challenge adult well-being? Positive relationships with significant others in our adult years have been found to contribute to a state of well-being (Ryff & Singer, 2009). Most adults in the United States identify themselves through their relationships with family—particularly with spouses, children, and parents (Markus et al., 2004). While raising children can be stressful, especially when they are young, research suggests that parents reap the rewards down the road, as adult children tend to have a positive effect on parental well-being (Umberson, Pudrovska, & Reczek, 2010). Having a stable marriage has also been found to contribute to well-being throughout adulthood (Vaillant, 2002). Another aspect of positive aging is believed to be social connectedness and social support. As we get older, socioemotional selectivity theory suggests that our social support and friendships dwindle in number, but remain as close, if not more close than in our earlier years (Carstensen, 1992) ( Figure 9.20 ). Link to Learning To learn more, view this video on aging in America. 9.4 Death and Dying Learning Objectives By the end of this section, you will be able to: Discuss hospice care Describe the five stages of grief Define living will and DNR Every story has an ending. Death marks the end of your life story ( Figure 9.21 ). Our culture and individual backgrounds influence how we view death. In some cultures, death is accepted as a natural part of life and is embraced. In contrast, until about 50 years ago in the United States, a doctor might not inform someone that they were dying, and the majority of deaths occurred in hospitals. In 1967 that reality began to change with Cicely Saunders, who created the first modern hospice in England. The aim of hospice is to help provide a death with dignity and pain management in a humane and comfortable environment, which is usually outside of a hospital setting. In 1974, Florence Wald founded the first hospice in the United States. Today, hospice provides care for 1.65 million Americans and their families. Because of hospice care, many terminally ill people are able to spend their last days at home. Research has indicated that hospice care is beneficial for the patient (Brumley, Enquidanos, & Cherin, 2003; Brumley et al., 2007; Godkin, Krant, & Doster, 1984) and for the patient’s family (Rhodes, Mitchell, Miller, Connor, & Teno, 2008; Godkin et al., 1984). Hospice patients report high levels of satisfaction with hospice care because they are able to remain at home and are not completely dependent on strangers for care (Brumley et al., 2007). In addition, hospice patients tend to live longer than non-hospice patients (Connor, Pyenson, Fitch, Spence, & Iwasaki, 2007; Temel et al., 2010). Family members receive emotional support and are regularly informed of their loved one’s treatment and condition. The family member’s burden of care is also reduced (McMillan et al., 2006). Both the patient and the patient’s family members report increased family support, increased social support, and improved coping while receiving hospice services (Godkin et al., 1984). How do you think you might react if you were diagnosed with a terminal illness like cancer? Elizabeth Kübler-Ross (1969), who worked with the founders of hospice care, described the process of an individual accepting his own death. She proposed five stages of grief: denial, anger, bargaining, depression, and acceptance. Most individuals experience these stages, but the stages may occur in different orders, depending on the individual. In addition, not all people experience all of the stages. It is also important to note that some psychologists believe that the more a dying person fights death, the more likely he is to remain stuck in the denial phase. This could make it difficult for the dying person to face death with dignity. However, other psychologists believe that not facing death until the very end is an adaptive coping mechanism for some people. Whether due to illness or old age, not everyone facing death or the loss of a loved one experiences the negative emotions outlined in the Kübler-Ross model (Nolen-Hoeksema & Larson, 1999). For example, research suggests that people with religious or spiritual beliefs are better able to cope with death because of their hope in an afterlife and because of social support from religious or spiritual associations (Hood, Spilka, Hunsberger, & Corsuch, 1996; McIntosh, Silver, & Wortman, 1993; Paloutzian, 1996; Samarel, 1991; Wortman & Park, 2008). A prominent example of a person creating meaning through death is Randy Pausch, who was a well-loved and respected professor at Carnegie Mellon University. Diagnosed with terminal pancreatic cancer in his mid-40s and given only 3–6 months to live, Pausch focused on living in a fulfilling way in the time he had left. Instead of becoming angry and depressed, he presented his now famous last lecture called “Really Achieving Your Childhood Dreams.” In his moving, yet humorous talk, he shares his insights on seeing the good in others, overcoming obstacles, and experiencing zero gravity, among many other things. Despite his terminal diagnosis, Pausch lived the final year of his life with joy and hope, showing us that our plans for the future still matter, even if we know that we are dying. Link to Learning Really Achieving Your Childhood Dreams is Randy Pausch’s last lecture. Listen to his inspiring talk. As individuals become more knowledgeable about medical procedures and practices, some people want to ensure that their wishes and desires are known in advance. This ensures that if the person ever becomes incapacitated or can no longer express herself, her loved ones will know what she wants. For this reason, a person might write a living will or advance directive , which is a written legal document that details specific interventions a person wants. For example, a person in the last stages of a terminal illness may not want to receive life-extending treatments. A person may also include a Do Not Resuscitate (DNR) Order and he would share this with his family and close friends. A DNR Order states that if a person stops breathing or his heart stops beating, medical personnel such as doctors and nurses are NOT to take steps to revive or resuscitate the patient. A living will can also include a health care proxy , which appoints a specific person to make medical decisions for you if you are unable to speak for yourself. People’s desire for living wills and DNRs are often influenced by their religion, culture, and upbringing.
anatomy_and_physiology
Chapter Objectives After studying this chapter, you will be able to: Describe the anatomy of the male and female reproductive systems, including their accessory structures Explain the role of hypothalamic and pituitary hormones in male and female reproductive function Trace the path of a sperm cell from its initial production through fertilization of an oocyte Explain the events in the ovary prior to ovulation Describe the development and maturation of the sex organs and the emergence of secondary sex characteristics during puberty Introduction Small, uncoordinated, and slick with amniotic fluid, a newborn encounters the world outside of her mother’s womb. We do not often consider that a child’s birth is proof of the healthy functioning of both her mother’s and father’s reproductive systems. Moreover, her parents’ endocrine systems had to secrete the appropriate regulating hormones to induce the production and release of unique male and female gametes, reproductive cells containing the parents’ genetic material (one set of 23 chromosomes). Her parent’s reproductive behavior had to facilitate the transfer of male gametes—the sperm—to the female reproductive tract at just the right time to encounter the female gamete, an oocyte (egg). Finally, combination of the gametes (fertilization) had to occur, followed by implantation and development. In this chapter, you will explore the male and female reproductive systems, whose healthy functioning can culminate in the powerful sound of a newborn’s first cry.
[ { "answer": { "ans_choice": 1, "ans_text": "sperm" }, "bloom": "1", "hl_context": "Unique for its role in human reproduction , a gamete is a specialized sex cell carrying 23 chromosomes — one half the number in body cells . <hl> At fertilization , the chromosomes in one male gamete , called a sperm ( or spermatozoon ) , combine with the chromosomes in one female gamete , called an oocyte . <hl> The function of the male reproductive system ( Figure 27.2 ) is to produce sperm and transfer them to the female reproductive tract . The paired testes are a crucial component in this process , as they produce both sperm and androgens , the hormones that support male reproductive physiology . In humans , the most important male androgen is testosterone . Several accessory organs and ducts aid the process of sperm maturation and transport the sperm and other seminal components to the penis , which delivers sperm to the female reproductive tract . In this section , we examine each of these different structures , and discuss the process of sperm production and transport .", "hl_sentences": "At fertilization , the chromosomes in one male gamete , called a sperm ( or spermatozoon ) , combine with the chromosomes in one female gamete , called an oocyte .", "question": { "cloze_format": "Male gametes are called ___ .", "normal_format": "What are male gametes called?", "question_choices": [ "ova", "sperm", "testes", "testosterone" ], "question_id": "fs-id2007602", "question_text": "What are male gametes called?" }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 0, "ans_text": "secrete testosterone" }, "bloom": null, "hl_context": "<hl> Soon after the formation of the testis , the Leydig cells begin to secrete testosterone . <hl> Testosterone can influence tissues that are bipotential to become male reproductive structures . For example , with exposure to testosterone , cells that could become either the glans penis or the glans clitoris form the glans penis . Without testosterone , these same cells differentiate into the clitoris . Testosterone , an androgen , is a steroid hormone produced by Leydig cells . The alternate term for Leydig cells , interstitial cells , reflects their location between the seminiferous tubules in the testes . <hl> In male embryos , testosterone is secreted by Leydig cells by the seventh week of development , with peak concentrations reached in the second trimester . <hl> This early release of testosterone results in the anatomical differentiation of the male sexual organs . In childhood , testosterone concentrations are low . They increase during puberty , activating characteristic physical changes and initiating spermatogenesis .", "hl_sentences": "Soon after the formation of the testis , the Leydig cells begin to secrete testosterone . In male embryos , testosterone is secreted by Leydig cells by the seventh week of development , with peak concentrations reached in the second trimester .", "question": { "cloze_format": "Leydig cells ________.", "normal_format": "What do Leydig cells?", "question_choices": [ "secrete testosterone", "activate the sperm flagellum", "support spermatogenesis", "secrete seminal fluid" ], "question_id": "fs-id2002473", "question_text": "Leydig cells ________." }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 1, "ans_text": "gonadotropin-releasing hormone" }, "bloom": "1", "hl_context": "The process of development that we have just described , from primordial follicle to early tertiary follicle , takes approximately two months in humans . The final stages of development of a small cohort of tertiary follicles , ending with ovulation of a secondary oocyte , occur over a course of approximately 28 days . <hl> These changes are regulated by many of the same hormones that regulate the male reproductive system , including GnRH , LH , and FSH . <hl> The regulation of Leydig cell production of testosterone begins outside of the testes . The hypothalamus and the pituitary gland in the brain integrate external and internal signals to control testosterone synthesis and secretion . The regulation begins in the hypothalamus . <hl> Pulsatile release of a hormone called gonadotropin-releasing hormone ( GnRH ) from the hypothalamus stimulates the endocrine release of hormones from the pituitary gland . <hl> Binding of GnRH to its receptors on the anterior pituitary gland stimulates release of the two gonadotropins : luteinizing hormone ( LH ) and follicle-stimulating hormone ( FSH ) . These two hormones are critical for reproductive function in both men and women . In men , FSH binds predominantly to the Sertoli cells within the seminiferous tubules to promote spermatogenesis . FSH also stimulates the Sertoli cells to produce hormones called inhibins , which function to inhibit FSH release from the pituitary , thus reducing testosterone secretion . These polypeptide hormones correlate directly with Sertoli cell function and sperm number ; inhibin B can be used as a marker of spermatogenic activity . In men , LH binds to receptors on Leydig cells in the testes and upregulates the production of testosterone .", "hl_sentences": "These changes are regulated by many of the same hormones that regulate the male reproductive system , including GnRH , LH , and FSH . Pulsatile release of a hormone called gonadotropin-releasing hormone ( GnRH ) from the hypothalamus stimulates the endocrine release of hormones from the pituitary gland .", "question": { "cloze_format": "The hypothalamic hormone that contributes to the regulation of the male reproductive system is called (the) ___ .", "normal_format": "Which hypothalamic hormone contributes to the regulation of the male reproductive system?", "question_choices": [ "luteinizing hormone", "gonadotropin-releasing hormone", "follicle-stimulating hormone", "androgens" ], "question_id": "fs-id2524700", "question_text": "Which hypothalamic hormone contributes to the regulation of the male reproductive system?" }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 0, "ans_text": "sperm maturation and storage" }, "bloom": "1", "hl_context": "<hl> From the lumen of the seminiferous tubules , the immotile sperm are surrounded by testicular fluid and moved to the epididymis ( plural = epididymides ) , a coiled tube attached to the testis where newly formed sperm continue to mature ( see Figure 27.4 ) . <hl> Though the epididymis does not take up much room in its tightly coiled state , it would be approximately 6 m ( 20 feet ) long if straightened . It takes an average of 12 days for sperm to move through the coils of the epididymis , with the shortest recorded transit time in humans being one day . Sperm enter the head of the epididymis and are moved along predominantly by the contraction of smooth muscles lining the epididymal tubes . As they are moved along the length of the epididymis , the sperm further mature and acquire the ability to move under their own power . Once inside the female reproductive tract , they will use this ability to move independently toward the unfertilized egg . <hl> The more mature sperm are then stored in the tail of the epididymis ( the final section ) until ejaculation occurs . <hl>", "hl_sentences": "From the lumen of the seminiferous tubules , the immotile sperm are surrounded by testicular fluid and moved to the epididymis ( plural = epididymides ) , a coiled tube attached to the testis where newly formed sperm continue to mature ( see Figure 27.4 ) . The more mature sperm are then stored in the tail of the epididymis ( the final section ) until ejaculation occurs .", "question": { "cloze_format": "The function of the epididymis is ___ .", "normal_format": "What is the function of the epididymis?", "question_choices": [ "sperm maturation and storage", "produces the bulk of seminal fluid", "provides nitric oxide needed for erections", "spermatogenesis" ], "question_id": "fs-id2752988", "question_text": "What is the function of the epididymis?" }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 2, "ans_text": "seminiferous tubules" }, "bloom": null, "hl_context": "<hl> As just noted , spermatogenesis occurs in the seminiferous tubules that form the bulk of each testis ( see Figure 27.4 ) . <hl> The process begins at puberty , after which time sperm are produced constantly throughout a man ’ s life . One production cycle , from spermatogonia through formed sperm , takes approximately 64 days . A new cycle starts approximately every 16 days , although this timing is not synchronous across the seminiferous tubules . Sperm counts — the total number of sperm a man produces — slowly decline after age 35 , and some studies suggest that smoking can lower sperm counts irrespective of age .", "hl_sentences": "As just noted , spermatogenesis occurs in the seminiferous tubules that form the bulk of each testis ( see Figure 27.4 ) .", "question": { "cloze_format": "Spermatogenesis takes place in the ________.", "normal_format": "Where does spermatogenesis take place?", "question_choices": [ "prostate gland", "glans penis", "seminiferous tubules", "ejaculatory duct" ], "question_id": "fs-id2915084", "question_text": "Spermatogenesis takes place in the ________." }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 3, "ans_text": "ovaries" }, "bloom": "1", "hl_context": "<hl> The ovaries are the female gonads ( see Figure 27.9 ) . <hl> Paired ovals , they are each about 2 to 3 cm in length , about the size of an almond . The ovaries are located within the pelvic cavity , and are supported by the mesovarium , an extension of the peritoneum that connects the ovaries to the broad ligament . Extending from the mesovarium itself is the suspensory ligament that contains the ovarian blood and lymph vessels . Finally , the ovary itself is attached to the uterus via the ovarian ligament . The female reproductive system functions to produce gametes and reproductive hormones , just like the male reproductive system ; however , it also has the additional task of supporting the developing fetus and delivering it to the outside world . Unlike its male counterpart , the female reproductive system is located primarily inside the pelvic cavity ( Figure 27.9 ) . <hl> Recall that the ovaries are the female gonads . <hl> The gamete they produce is called an oocyte . We ’ ll discuss the production of oocytes in detail shortly . First , let ’ s look at some of the structures of the female reproductive system .", "hl_sentences": "The ovaries are the female gonads ( see Figure 27.9 ) . Recall that the ovaries are the female gonads .", "question": { "cloze_format": "The female gonads are called ___ .", "normal_format": "What are the female gonads called?", "question_choices": [ "oocytes", "ova", "oviducts", "ovaries" ], "question_id": "fs-id2369971", "question_text": "What are the female gonads called?" }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 0, "ans_text": "before birth" }, "bloom": null, "hl_context": "Gametogenesis in females is called oogenesis . The process begins with the ovarian stem cells , or oogonia ( Figure 27.11 ) . <hl> Oogonia are formed during fetal development , and divide via mitosis , much like spermatogonia in the testis . <hl> <hl> Unlike spermatogonia , however , oogonia form primary oocytes in the fetal ovary prior to birth . <hl> These primary oocytes are then arrested in this stage of meiosis I , only to resume it years later , beginning at puberty and continuing until the woman is near menopause ( the cessation of a woman ’ s reproductive functions ) . The number of primary oocytes present in the ovaries declines from one to two million in an infant , to approximately 400,000 at puberty , to zero by the end of menopause .", "hl_sentences": "Oogonia are formed during fetal development , and divide via mitosis , much like spermatogonia in the testis . Unlike spermatogonia , however , oogonia form primary oocytes in the fetal ovary prior to birth .", "question": { "cloze_format": "The oogonia undergo mitosis ___.", "normal_format": "When do the oogonia undergo mitosis?", "question_choices": [ "before birth", "at puberty", "at the beginning of each menstrual cycle", "during fertilization" ], "question_id": "fs-id1520756", "question_text": "When do the oogonia undergo mitosis?" }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 1, "ans_text": "dominant follicle" }, "bloom": "1", "hl_context": "In the next section , you will follow the ovulated oocyte as it travels toward the uterus , but there is one more important event that occurs in the ovarian cycle . The surge of LH also stimulates a change in the granulosa and theca cells that remain in the follicle after the oocyte has been ovulated . <hl> This change is called luteinization ( recall that the full name of LH is luteinizing hormone ) , and it transforms the collapsed follicle into a new endocrine structure called the corpus luteum , a term meaning “ yellowish body ” ( see Figure 27.12 ) . <hl> Instead of estrogen , the luteinized granulosa and theca cells of the corpus luteum begin to produce large amounts of the sex steroid hormone progesterone , a hormone that is critical for the establishment and maintenance of pregnancy . Progesterone triggers negative feedback at the hypothalamus and pituitary , which keeps GnRH , LH , and FSH secretions low , so no new dominant follicles develop at this time .", "hl_sentences": "This change is called luteinization ( recall that the full name of LH is luteinizing hormone ) , and it transforms the collapsed follicle into a new endocrine structure called the corpus luteum , a term meaning “ yellowish body ” ( see Figure 27.12 ) .", "question": { "cloze_format": "The structure that the corpus luteum originates from is the ___.", "normal_format": "From what structure does the corpus luteum originate?", "question_choices": [ "uterine corpus", "dominant follicle", "fallopian tube", "corpus albicans" ], "question_id": "fs-id1591190", "question_text": "From what structure does the corpus luteum originate?" }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 2, "ans_text": "uterine tube" }, "bloom": "1", "hl_context": "<hl> The uterine tubes ( also called fallopian tubes or oviducts ) serve as the conduit of the oocyte from the ovary to the uterus ( Figure 27.14 ) . <hl> Each of the two uterine tubes is close to , but not directly connected to , the ovary and divided into sections . The isthmus is the narrow medial end of each uterine tube that is connected to the uterus . The wide distal infundibulum flares out with slender , finger-like projections called fimbriae . <hl> The middle region of the tube , called the ampulla , is where fertilization often occurs . <hl> The uterine tubes also have three layers : an outer serosa , a middle smooth muscle layer , and an inner mucosal layer . In addition to its mucus-secreting cells , the inner mucosa contains ciliated cells that beat in the direction of the uterus , producing a current that will be critical to move the oocyte .", "hl_sentences": "The uterine tubes ( also called fallopian tubes or oviducts ) serve as the conduit of the oocyte from the ovary to the uterus ( Figure 27.14 ) . The middle region of the tube , called the ampulla , is where fertilization often occurs .", "question": { "cloze_format": "The location where fertilization of the egg by the sperm typically occurs is in the ___ .", "normal_format": "Where does fertilization of the egg by the sperm typically occur?", "question_choices": [ "vagina", "uterus", "uterine tube", "ovary" ], "question_id": "fs-id2488610", "question_text": "Where does fertilization of the egg by the sperm typically occur?" }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 1, "ans_text": "There are no follicles left to produce estrogen. " }, "bloom": "3", "hl_context": "As a woman reaches the age of menopause , depletion of the number of viable follicles in the ovaries due to atresia affects the hormonal regulation of the menstrual cycle . During the years leading up to menopause , there is a decrease in the levels of the hormone inhibin , which normally participates in a negative feedback loop to the pituitary to control the production of FSH . The menopausal decrease in inhibin leads to an increase in FSH . The presence of FSH stimulates more follicles to grow and secrete estrogen . Because small , secondary follicles also respond to increases in FSH levels , larger numbers of follicles are stimulated to grow ; however , most undergo atresia and die . <hl> Eventually , this process leads to the depletion of all follicles in the ovaries , and the production of estrogen falls off dramatically . <hl> <hl> It is primarily the lack of estrogens that leads to the symptoms of menopause . <hl>", "hl_sentences": "Eventually , this process leads to the depletion of all follicles in the ovaries , and the production of estrogen falls off dramatically . It is primarily the lack of estrogens that leads to the symptoms of menopause .", "question": { "cloze_format": "Estrogen levels fall after menopause because ___ .", "normal_format": "Why do estrogen levels fall after menopause?", "question_choices": [ "The ovaries degrade. ", "There are no follicles left to produce estrogen. ", "The pituitary secretes a menopause-specific hormone. ", "The cells of the endometrium degenerate." ], "question_id": "fs-id2641762", "question_text": "Why do estrogen levels fall after menopause?" }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 3, "ans_text": "mons pubis, labia majora, and Bartholin’s glands" }, "bloom": "1", "hl_context": "<hl> The external female reproductive structures are referred to collectively as the vulva ( Figure 27.10 ) . <hl> <hl> The mons pubis is a pad of fat that is located at the anterior , over the pubic bone . <hl> After puberty , it becomes covered in pubic hair . <hl> The labia majora ( labia = “ lips ” ; majora = “ larger ” ) are folds of hair-covered skin that begin just posterior to the mons pubis . <hl> The thinner and more pigmented labia minora ( labia = “ lips ” ; minora = “ smaller ” ) extend medial to the labia majora . Although they naturally vary in shape and size from woman to woman , the labia minora serve to protect the female urethra and the entrance to the female reproductive tract . The superior , anterior portions of the labia minora come together to encircle the clitoris ( or glans clitoris ) , an organ that originates from the same cells as the glans penis and has abundant nerves that make it important in sexual sensation and orgasm . The hymen is a thin membrane that sometimes partially covers the entrance to the vagina . An intact hymen cannot be used as an indication of “ virginity ” ; even at birth , this is only a partial membrane , as menstrual fluid and other secretions must be able to exit the body , regardless of penile – vaginal intercourse . The vaginal opening is located between the opening of the urethra and the anus . <hl> It is flanked by outlets to the Bartholin ’ s glands ( or greater vestibular glands ) . <hl>", "hl_sentences": "The external female reproductive structures are referred to collectively as the vulva ( Figure 27.10 ) . The mons pubis is a pad of fat that is located at the anterior , over the pubic bone . The labia majora ( labia = “ lips ” ; majora = “ larger ” ) are folds of hair-covered skin that begin just posterior to the mons pubis . It is flanked by outlets to the Bartholin ’ s glands ( or greater vestibular glands ) .", "question": { "cloze_format": "The vulva includes the ________.", "normal_format": "What does the vulva include?", "question_choices": [ "lactiferous duct, rugae, and hymen", "lactiferous duct, endometrium, and bulbourethral glands", "mons pubis, endometrium, and hymen", "mons pubis, labia majora, and Bartholin’s glands" ], "question_id": "fs-id2512009", "question_text": "The vulva includes the ________." }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 1, "ans_text": "female reproductive structures" }, "bloom": null, "hl_context": "Females are considered the “ fundamental ” sex — that is , without much chemical prompting , all fertilized eggs would develop into females . <hl> To become a male , an individual must be exposed to the cascade of factors initiated by a single gene on the male Y chromosome . <hl> <hl> This is called the SRY ( S ex-determining R egion of the Y chromosome ) . <hl> <hl> Because females do not have a Y chromosome , they do not have the SRY gene . <hl> <hl> Without a functional SRY gene , an individual will be female . <hl>", "hl_sentences": "To become a male , an individual must be exposed to the cascade of factors initiated by a single gene on the male Y chromosome . This is called the SRY ( S ex-determining R egion of the Y chromosome ) . Because females do not have a Y chromosome , they do not have the SRY gene . Without a functional SRY gene , an individual will be female .", "question": { "cloze_format": "Without SRY expression, an embryo will develop ________.", "normal_format": "Without SRY expression, what will an embryo develop?", "question_choices": [ "male reproductive structures", "female reproductive structures", "no reproductive structures", "male reproductive structures 50 percent of the time and female reproductive structures 50 percent of the time" ], "question_id": "fs-id1576900", "question_text": "Without SRY expression, an embryo will develop ________." }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 3, "ans_text": "all of the above" }, "bloom": "1", "hl_context": "<hl> In addition to age , multiple factors can affect the age of onset of puberty , including genetics , environment , and psychological stress . <hl> One of the more important influences may be nutrition ; historical data demonstrate the effect of better and more consistent nutrition on the age of menarche in girls in the United States , which decreased from an average age of approximately 17 years of age in 1860 to the current age of approximately 12.75 years in 1960 , as it remains today . Some studies indicate a link between puberty onset and the amount of stored fat in an individual . This effect is more pronounced in girls , but has been documented in both sexes . <hl> Body fat , corresponding with secretion of the hormone leptin by adipose cells , appears to have a strong role in determining menarche . <hl> This may reflect to some extent the high metabolic costs of gestation and lactation . In girls who are lean and highly active , such as gymnasts , there is often a delay in the onset of puberty .", "hl_sentences": "In addition to age , multiple factors can affect the age of onset of puberty , including genetics , environment , and psychological stress . Body fat , corresponding with secretion of the hormone leptin by adipose cells , appears to have a strong role in determining menarche .", "question": { "cloze_format": "The timing of puberty can be influenced by (the) ___ .", "normal_format": "The timing of puberty can be influenced by which of the following?", "question_choices": [ "genes", "stress", "amount of body fat", "all of the above" ], "question_id": "fs-id2633194", "question_text": "The timing of puberty can be influenced by which of the following?" }, "references_are_paraphrase": 0 } ]
27
27.1 Anatomy and Physiology of the Male Reproductive System Learning Objectives By the end of this section, you will be able to: Describe the structure and function of the organs of the male reproductive system Describe the structure and function of the sperm cell Explain the events during spermatogenesis that produce haploid sperm from diploid cells Identify the importance of testosterone in male reproductive function Unique for its role in human reproduction, a gamete is a specialized sex cell carrying 23 chromosomes—one half the number in body cells. At fertilization, the chromosomes in one male gamete, called a sperm (or spermatozoon), combine with the chromosomes in one female gamete, called an oocyte. The function of the male reproductive system ( Figure 27.2 ) is to produce sperm and transfer them to the female reproductive tract. The paired testes are a crucial component in this process, as they produce both sperm and androgens, the hormones that support male reproductive physiology. In humans, the most important male androgen is testosterone. Several accessory organs and ducts aid the process of sperm maturation and transport the sperm and other seminal components to the penis, which delivers sperm to the female reproductive tract. In this section, we examine each of these different structures, and discuss the process of sperm production and transport. Scrotum The testes are located in a skin-covered, highly pigmented, muscular sack called the scrotum that extends from the body behind the penis (see Figure 27.2 ). This location is important in sperm production, which occurs within the testes, and proceeds more efficiently when the testes are kept 2 to 4°C below core body temperature. The dartos muscle makes up the subcutaneous muscle layer of the scrotum ( Figure 27.3 ). It continues internally to make up the scrotal septum, a wall that divides the scrotum into two compartments, each housing one testis. Descending from the internal oblique muscle of the abdominal wall are the two cremaster muscles, which cover each testis like a muscular net. By contracting simultaneously, the dartos and cremaster muscles can elevate the testes in cold weather (or water), moving the testes closer to the body and decreasing the surface area of the scrotum to retain heat. Alternatively, as the environmental temperature increases, the scrotum relaxes, moving the testes farther from the body core and increasing scrotal surface area, which promotes heat loss. Externally, the scrotum has a raised medial thickening on the surface called the raphae. Testes The testes (singular = testis) are the male gonads —that is, the male reproductive organs. They produce both sperm and androgens, such as testosterone, and are active throughout the reproductive lifespan of the male. Paired ovals, the testes are each approximately 4 to 5 cm in length and are housed within the scrotum (see Figure 27.3 ). They are surrounded by two distinct layers of protective connective tissue ( Figure 27.4 ). The outer tunica vaginalis is a serous membrane that has both a parietal and a thin visceral layer. Beneath the tunica vaginalis is the tunica albuginea, a tough, white, dense connective tissue layer covering the testis itself. Not only does the tunica albuginea cover the outside of the testis, it also invaginates to form septa that divide the testis into 300 to 400 structures called lobules. Within the lobules, sperm develop in structures called seminiferous tubules. During the seventh month of the developmental period of a male fetus, each testis moves through the abdominal musculature to descend into the scrotal cavity. This is called the “descent of the testis.” Cryptorchidism is the clinical term used when one or both of the testes fail to descend into the scrotum prior to birth. The tightly coiled seminiferous tubules form the bulk of each testis. They are composed of developing sperm cells surrounding a lumen, the hollow center of the tubule, where formed sperm are released into the duct system of the testis. Specifically, from the lumens of the seminiferous tubules, sperm move into the straight tubules (or tubuli recti), and from there into a fine meshwork of tubules called the rete testes. Sperm leave the rete testes, and the testis itself, through the 15 to 20 efferent ductules that cross the tunica albuginea. Inside the seminiferous tubules are six different cell types. These include supporting cells called sustentacular cells, as well as five types of developing sperm cells called germ cells. Germ cell development progresses from the basement membrane—at the perimeter of the tubule—toward the lumen. Let’s look more closely at these cell types. Sertoli Cells Surrounding all stages of the developing sperm cells are elongate, branching Sertoli cells . Sertoli cells are a type of supporting cell called a sustentacular cell, or sustentocyte, that are typically found in epithelial tissue. Sertoli cells secrete signaling molecules that promote sperm production and can control whether germ cells live or die. They extend physically around the germ cells from the peripheral basement membrane of the seminiferous tubules to the lumen. Tight junctions between these sustentacular cells create the blood–testis barrier , which keeps bloodborne substances from reaching the germ cells and, at the same time, keeps surface antigens on developing germ cells from escaping into the bloodstream and prompting an autoimmune response. Germ Cells The least mature cells, the spermatogonia (singular = spermatogonium), line the basement membrane inside the tubule. Spermatogonia are the stem cells of the testis, which means that they are still able to differentiate into a variety of different cell types throughout adulthood. Spermatogonia divide to produce primary and secondary spermatocytes, then spermatids, which finally produce formed sperm. The process that begins with spermatogonia and concludes with the production of sperm is called spermatogenesis . Spermatogenesis As just noted, spermatogenesis occurs in the seminiferous tubules that form the bulk of each testis (see Figure 27.4 ). The process begins at puberty, after which time sperm are produced constantly throughout a man’s life. One production cycle, from spermatogonia through formed sperm, takes approximately 64 days. A new cycle starts approximately every 16 days, although this timing is not synchronous across the seminiferous tubules. Sperm counts—the total number of sperm a man produces—slowly decline after age 35, and some studies suggest that smoking can lower sperm counts irrespective of age. The process of spermatogenesis begins with mitosis of the diploid spermatogonia ( Figure 27.5 ). Because these cells are diploid (2 n ), they each have a complete copy of the father’s genetic material, or 46 chromosomes. However, mature gametes are haploid (1 n ), containing 23 chromosomes—meaning that daughter cells of spermatogonia must undergo a second cellular division through the process of meiosis. Two identical diploid cells result from spermatogonia mitosis. One of these cells remains a spermatogonium, and the other becomes a primary spermatocyte , the next stage in the process of spermatogenesis. As in mitosis, DNA is replicated in a primary spermatocyte, before it undergoes a cell division called meiosis I. During meiosis I each of the 23 pairs of chromosomes separates. This results in two cells, called secondary spermatocytes, each with only half the number of chromosomes. Now a second round of cell division (meiosis II) occurs in both of the secondary spermatocytes. During meiosis II each of the 23 replicated chromosomes divides, similar to what happens during mitosis. Thus, meiosis results in separating the chromosome pairs. This second meiotic division results in a total of four cells with only half of the number of chromosomes. Each of these new cells is a spermatid . Although haploid, early spermatids look very similar to cells in the earlier stages of spermatogenesis, with a round shape, central nucleus, and large amount of cytoplasm. A process called spermiogenesis transforms these early spermatids, reducing the cytoplasm, and beginning the formation of the parts of a true sperm. The fifth stage of germ cell formation—spermatozoa, or formed sperm—is the end result of this process, which occurs in the portion of the tubule nearest the lumen. Eventually, the sperm are released into the lumen and are moved along a series of ducts in the testis toward a structure called the epididymis for the next step of sperm maturation. Structure of Formed Sperm Sperm are smaller than most cells in the body; in fact, the volume of a sperm cell is 85,000 times less than that of the female gamete. Approximately 100 to 300 million sperm are produced each day, whereas women typically ovulate only one oocyte per month. As is true for most cells in the body, the structure of sperm cells speaks to their function. Sperm have a distinctive head, mid-piece, and tail region ( Figure 27.6 ). The head of the sperm contains the extremely compact haploid nucleus with very little cytoplasm. These qualities contribute to the overall small size of the sperm (the head is only 5 μ m long). A structure called the acrosome covers most of the head of the sperm cell as a “cap” that is filled with lysosomal enzymes important for preparing sperm to participate in fertilization. Tightly packed mitochondria fill the mid-piece of the sperm. ATP produced by these mitochondria will power the flagellum, which extends from the neck and the mid-piece through the tail of the sperm, enabling it to move the entire sperm cell. The central strand of the flagellum, the axial filament, is formed from one centriole inside the maturing sperm cell during the final stages of spermatogenesis. Sperm Transport To fertilize an egg, sperm must be moved from the seminiferous tubules in the testes, through the epididymis, and—later during ejaculation—along the length of the penis and out into the female reproductive tract. Role of the Epididymis From the lumen of the seminiferous tubules, the immotile sperm are surrounded by testicular fluid and moved to the epididymis (plural = epididymides), a coiled tube attached to the testis where newly formed sperm continue to mature (see Figure 27.4 ). Though the epididymis does not take up much room in its tightly coiled state, it would be approximately 6 m (20 feet) long if straightened. It takes an average of 12 days for sperm to move through the coils of the epididymis, with the shortest recorded transit time in humans being one day. Sperm enter the head of the epididymis and are moved along predominantly by the contraction of smooth muscles lining the epididymal tubes. As they are moved along the length of the epididymis, the sperm further mature and acquire the ability to move under their own power. Once inside the female reproductive tract, they will use this ability to move independently toward the unfertilized egg. The more mature sperm are then stored in the tail of the epididymis (the final section) until ejaculation occurs. Duct System During ejaculation, sperm exit the tail of the epididymis and are pushed by smooth muscle contraction to the ductus deferens (also called the vas deferens). The ductus deferens is a thick, muscular tube that is bundled together inside the scrotum with connective tissue, blood vessels, and nerves into a structure called the spermatic cord (see Figure 27.2 and Figure 27.3 ). Because the ductus deferens is physically accessible within the scrotum, surgical sterilization to interrupt sperm delivery can be performed by cutting and sealing a small section of the ductus (vas) deferens. This procedure is called a vasectomy, and it is an effective form of male birth control. Although it may be possible to reverse a vasectomy, clinicians consider the procedure permanent, and advise men to undergo it only if they are certain they no longer wish to father children. Interactive Link Watch this video to learn about a vasectomy. As described in this video, a vasectomy is a procedure in which a small section of the ductus (vas) deferens is removed from the scrotum. This interrupts the path taken by sperm through the ductus deferens. If sperm do not exit through the vas, either because the man has had a vasectomy or has not ejaculated, in what region of the testis do they remain? From each epididymis, each ductus deferens extends superiorly into the abdominal cavity through the inguinal canal in the abdominal wall. From here, the ductus deferens continues posteriorly to the pelvic cavity, ending posterior to the bladder where it dilates in a region called the ampulla (meaning “flask”). Sperm make up only 5 percent of the final volume of semen , the thick, milky fluid that the male ejaculates. The bulk of semen is produced by three critical accessory glands of the male reproductive system: the seminal vesicles, the prostate, and the bulbourethral glands. Seminal Vesicles As sperm pass through the ampulla of the ductus deferens at ejaculation, they mix with fluid from the associated seminal vesicle (see Figure 27.2 ). The paired seminal vesicles are glands that contribute approximately 60 percent of the semen volume. Seminal vesicle fluid contains large amounts of fructose, which is used by the sperm mitochondria to generate ATP to allow movement through the female reproductive tract. The fluid, now containing both sperm and seminal vesicle secretions, next moves into the associated ejaculatory duct , a short structure formed from the ampulla of the ductus deferens and the duct of the seminal vesicle. The paired ejaculatory ducts transport the seminal fluid into the next structure, the prostate gland. Prostate Gland As shown in Figure 27.2 , the centrally located prostate gland sits anterior to the rectum at the base of the bladder surrounding the prostatic urethra (the portion of the urethra that runs within the prostate). About the size of a walnut, the prostate is formed of both muscular and glandular tissues. It excretes an alkaline, milky fluid to the passing seminal fluid—now called semen—that is critical to first coagulate and then decoagulate the semen following ejaculation. The temporary thickening of semen helps retain it within the female reproductive tract, providing time for sperm to utilize the fructose provided by seminal vesicle secretions. When the semen regains its fluid state, sperm can then pass farther into the female reproductive tract. The prostate normally doubles in size during puberty. At approximately age 25, it gradually begins to enlarge again. This enlargement does not usually cause problems; however, abnormal growth of the prostate, or benign prostatic hyperplasia (BPH), can cause constriction of the urethra as it passes through the middle of the prostate gland, leading to a number of lower urinary tract symptoms, such as a frequent and intense urge to urinate, a weak stream, and a sensation that the bladder has not emptied completely. By age 60, approximately 40 percent of men have some degree of BPH. By age 80, the number of affected individuals has jumped to as many as 80 percent. Treatments for BPH attempt to relieve the pressure on the urethra so that urine can flow more normally. Mild to moderate symptoms are treated with medication, whereas severe enlargement of the prostate is treated by surgery in which a portion of the prostate tissue is removed. Another common disorder involving the prostate is prostate cancer. According to the Centers for Disease Control and Prevention (CDC), prostate cancer is the second most common cancer in men. However, some forms of prostate cancer grow very slowly and thus may not ever require treatment. Aggressive forms of prostate cancer, in contrast, involve metastasis to vulnerable organs like the lungs and brain. There is no link between BPH and prostate cancer, but the symptoms are similar. Prostate cancer is detected by a medical history, a blood test, and a rectal exam that allows physicians to palpate the prostate and check for unusual masses. If a mass is detected, the cancer diagnosis is confirmed by biopsy of the cells. Bulbourethral Glands The final addition to semen is made by two bulbourethral glands (or Cowper’s glands) that release a thick, salty fluid that lubricates the end of the urethra and the vagina, and helps to clean urine residues from the penile urethra. The fluid from these accessory glands is released after the male becomes sexually aroused, and shortly before the release of the semen. It is therefore sometimes called pre-ejaculate. It is important to note that, in addition to the lubricating proteins, it is possible for bulbourethral fluid to pick up sperm already present in the urethra, and therefore it may be able to cause pregnancy. Interactive Link Watch this video to explore the structures of the male reproductive system and the path of sperm, which starts in the testes and ends as the sperm leave the penis through the urethra. Where are sperm deposited after they leave the ejaculatory duct? The Penis The penis is the male organ of copulation (sexual intercourse). It is flaccid for non-sexual actions, such as urination, and turgid and rod-like with sexual arousal. When erect, the stiffness of the organ allows it to penetrate into the vagina and deposit semen into the female reproductive tract. The shaft of the penis surrounds the urethra ( Figure 27.7 ). The shaft is composed of three column-like chambers of erectile tissue that span the length of the shaft. Each of the two larger lateral chambers is called a corpus cavernosum (plural = corpora cavernosa). Together, these make up the bulk of the penis. The corpus spongiosum , which can be felt as a raised ridge on the erect penis, is a smaller chamber that surrounds the spongy, or penile, urethra. The end of the penis, called the glans penis , has a high concentration of nerve endings, resulting in very sensitive skin that influences the likelihood of ejaculation (see Figure 27.2 ). The skin from the shaft extends down over the glans and forms a collar called the prepuce (or foreskin). The foreskin also contains a dense concentration of nerve endings, and both lubricate and protect the sensitive skin of the glans penis. A surgical procedure called circumcision, often performed for religious or social reasons, removes the prepuce, typically within days of birth. Both sexual arousal and REM sleep (during which dreaming occurs) can induce an erection. Penile erections are the result of vasocongestion, or engorgement of the tissues because of more arterial blood flowing into the penis than is leaving in the veins. During sexual arousal, nitric oxide (NO) is released from nerve endings near blood vessels within the corpora cavernosa and spongiosum. Release of NO activates a signaling pathway that results in relaxation of the smooth muscles that surround the penile arteries, causing them to dilate. This dilation increases the amount of blood that can enter the penis and induces the endothelial cells in the penile arterial walls to also secrete NO and perpetuate the vasodilation. The rapid increase in blood volume fills the erectile chambers, and the increased pressure of the filled chambers compresses the thin-walled penile venules, preventing venous drainage of the penis. The result of this increased blood flow to the penis and reduced blood return from the penis is erection. Depending on the flaccid dimensions of a penis, it can increase in size slightly or greatly during erection, with the average length of an erect penis measuring approximately 15 cm. Disorders of the... Male Reproductive System Erectile dysfunction (ED) is a condition in which a man has difficulty either initiating or maintaining an erection. The combined prevalence of minimal, moderate, and complete ED is approximately 40 percent in men at age 40, and reaches nearly 70 percent by 70 years of age. In addition to aging, ED is associated with diabetes, vascular disease, psychiatric disorders, prostate disorders, the use of some drugs such as certain antidepressants, and problems with the testes resulting in low testosterone concentrations. These physical and emotional conditions can lead to interruptions in the vasodilation pathway and result in an inability to achieve an erection. Recall that the release of NO induces relaxation of the smooth muscles that surround the penile arteries, leading to the vasodilation necessary to achieve an erection. To reverse the process of vasodilation, an enzyme called phosphodiesterase (PDE) degrades a key component of the NO signaling pathway called cGMP. There are several different forms of this enzyme, and PDE type 5 is the type of PDE found in the tissues of the penis. Scientists discovered that inhibiting PDE5 increases blood flow, and allows vasodilation of the penis to occur. PDEs and the vasodilation signaling pathway are found in the vasculature in other parts of the body. In the 1990s, clinical trials of a PDE5 inhibitor called sildenafil were initiated to treat hypertension and angina pectoris (chest pain caused by poor blood flow through the heart). The trial showed that the drug was not effective at treating heart conditions, but many men experienced erection and priapism (erection lasting longer than 4 hours). Because of this, a clinical trial was started to investigate the ability of sildenafil to promote erections in men suffering from ED. In 1998, the FDA approved the drug, marketed as Viagra ® . Since approval of the drug, sildenafil and similar PDE inhibitors now generate over a billion dollars a year in sales, and are reported to be effective in treating approximately 70 to 85 percent of cases of ED. Importantly, men with health problems—especially those with cardiac disease taking nitrates—should avoid Viagra or talk to their physician to find out if they are a candidate for the use of this drug, as deaths have been reported for at-risk users. Testosterone Testosterone, an androgen, is a steroid hormone produced by Leydig cells . The alternate term for Leydig cells, interstitial cells, reflects their location between the seminiferous tubules in the testes. In male embryos, testosterone is secreted by Leydig cells by the seventh week of development, with peak concentrations reached in the second trimester. This early release of testosterone results in the anatomical differentiation of the male sexual organs. In childhood, testosterone concentrations are low. They increase during puberty, activating characteristic physical changes and initiating spermatogenesis. Functions of Testosterone The continued presence of testosterone is necessary to keep the male reproductive system working properly, and Leydig cells produce approximately 6 to 7 mg of testosterone per day. Testicular steroidogenesis (the manufacture of androgens, including testosterone) results in testosterone concentrations that are 100 times higher in the testes than in the circulation. Maintaining these normal concentrations of testosterone promotes spermatogenesis, whereas low levels of testosterone can lead to infertility. In addition to intratesticular secretion, testosterone is also released into the systemic circulation and plays an important role in muscle development, bone growth, the development of secondary sex characteristics, and maintaining libido (sex drive) in both males and females. In females, the ovaries secrete small amounts of testosterone, although most is converted to estradiol. A small amount of testosterone is also secreted by the adrenal glands in both sexes. Control of Testosterone The regulation of testosterone concentrations throughout the body is critical for male reproductive function. The intricate interplay between the endocrine system and the reproductive system is shown in Figure 27.8 . The regulation of Leydig cell production of testosterone begins outside of the testes. The hypothalamus and the pituitary gland in the brain integrate external and internal signals to control testosterone synthesis and secretion. The regulation begins in the hypothalamus. Pulsatile release of a hormone called gonadotropin-releasing hormone (GnRH) from the hypothalamus stimulates the endocrine release of hormones from the pituitary gland. Binding of GnRH to its receptors on the anterior pituitary gland stimulates release of the two gonadotropins: luteinizing hormone (LH) and follicle-stimulating hormone (FSH). These two hormones are critical for reproductive function in both men and women. In men, FSH binds predominantly to the Sertoli cells within the seminiferous tubules to promote spermatogenesis. FSH also stimulates the Sertoli cells to produce hormones called inhibins, which function to inhibit FSH release from the pituitary, thus reducing testosterone secretion. These polypeptide hormones correlate directly with Sertoli cell function and sperm number; inhibin B can be used as a marker of spermatogenic activity. In men, LH binds to receptors on Leydig cells in the testes and upregulates the production of testosterone. A negative feedback loop predominantly controls the synthesis and secretion of both FSH and LH. Low blood concentrations of testosterone stimulate the hypothalamic release of GnRH. GnRH then stimulates the anterior pituitary to secrete LH into the bloodstream. In the testis, LH binds to LH receptors on Leydig cells and stimulates the release of testosterone. When concentrations of testosterone in the blood reach a critical threshold, testosterone itself will bind to androgen receptors on both the hypothalamus and the anterior pituitary, inhibiting the synthesis and secretion of GnRH and LH, respectively. When the blood concentrations of testosterone once again decline, testosterone no longer interacts with the receptors to the same degree and GnRH and LH are once again secreted, stimulating more testosterone production. This same process occurs with FSH and inhibin to control spermatogenesis. Aging and the... Male Reproductive System Declines in Leydig cell activity can occur in men beginning at 40 to 50 years of age. The resulting reduction in circulating testosterone concentrations can lead to symptoms of andropause, also known as male menopause. While the reduction in sex steroids in men is akin to female menopause, there is no clear sign—such as a lack of a menstrual period—to denote the initiation of andropause. Instead, men report feelings of fatigue, reduced muscle mass, depression, anxiety, irritability, loss of libido, and insomnia. A reduction in spermatogenesis resulting in lowered fertility is also reported, and sexual dysfunction can also be associated with andropausal symptoms. Whereas some researchers believe that certain aspects of andropause are difficult to tease apart from aging in general, testosterone replacement is sometimes prescribed to alleviate some symptoms. Recent studies have shown a benefit from androgen replacement therapy on the new onset of depression in elderly men; however, other studies caution against testosterone replacement for long-term treatment of andropause symptoms, showing that high doses can sharply increase the risk of both heart disease and prostate cancer. 27.2 Anatomy and Physiology of the Female Reproductive System Learning Objectives By the end of this section, you will be able to: Describe the structure and function of the organs of the female reproductive system List the steps of oogenesis Describe the hormonal changes that occur during the ovarian and menstrual cycles Trace the path of an oocyte from ovary to fertilization The female reproductive system functions to produce gametes and reproductive hormones, just like the male reproductive system; however, it also has the additional task of supporting the developing fetus and delivering it to the outside world. Unlike its male counterpart, the female reproductive system is located primarily inside the pelvic cavity ( Figure 27.9 ). Recall that the ovaries are the female gonads. The gamete they produce is called an oocyte . We’ll discuss the production of oocytes in detail shortly. First, let’s look at some of the structures of the female reproductive system. External Female Genitals The external female reproductive structures are referred to collectively as the vulva ( Figure 27.10 ). The mons pubis is a pad of fat that is located at the anterior, over the pubic bone. After puberty, it becomes covered in pubic hair. The labia majora (labia = “lips”; majora = “larger”) are folds of hair-covered skin that begin just posterior to the mons pubis. The thinner and more pigmented labia minora (labia = “lips”; minora = “smaller”) extend medial to the labia majora. Although they naturally vary in shape and size from woman to woman, the labia minora serve to protect the female urethra and the entrance to the female reproductive tract. The superior, anterior portions of the labia minora come together to encircle the clitoris (or glans clitoris), an organ that originates from the same cells as the glans penis and has abundant nerves that make it important in sexual sensation and orgasm. The hymen is a thin membrane that sometimes partially covers the entrance to the vagina. An intact hymen cannot be used as an indication of “virginity”; even at birth, this is only a partial membrane, as menstrual fluid and other secretions must be able to exit the body, regardless of penile–vaginal intercourse. The vaginal opening is located between the opening of the urethra and the anus. It is flanked by outlets to the Bartholin’s glands (or greater vestibular glands). Vagina The vagina , shown at the bottom of Figure 27.9 and Figure 27.9 , is a muscular canal (approximately 10 cm long) that serves as the entrance to the reproductive tract. It also serves as the exit from the uterus during menses and childbirth. The outer walls of the anterior and posterior vagina are formed into longitudinal columns, or ridges, and the superior portion of the vagina—called the fornix—meets the protruding uterine cervix. The walls of the vagina are lined with an outer, fibrous adventitia; a middle layer of smooth muscle; and an inner mucous membrane with transverse folds called rugae . Together, the middle and inner layers allow the expansion of the vagina to accommodate intercourse and childbirth. The thin, perforated hymen can partially surround the opening to the vaginal orifice. The hymen can be ruptured with strenuous physical exercise, penile–vaginal intercourse, and childbirth. The Bartholin’s glands and the lesser vestibular glands (located near the clitoris) secrete mucus, which keeps the vestibular area moist. The vagina is home to a normal population of microorganisms that help to protect against infection by pathogenic bacteria, yeast, or other organisms that can enter the vagina. In a healthy woman, the most predominant type of vaginal bacteria is from the genus Lactobacillus . This family of beneficial bacterial flora secretes lactic acid, and thus protects the vagina by maintaining an acidic pH (below 4.5). Potential pathogens are less likely to survive in these acidic conditions. Lactic acid, in combination with other vaginal secretions, makes the vagina a self-cleansing organ. However, douching—or washing out the vagina with fluid—can disrupt the normal balance of healthy microorganisms, and actually increase a woman’s risk for infections and irritation. Indeed, the American College of Obstetricians and Gynecologists recommend that women do not douche, and that they allow the vagina to maintain its normal healthy population of protective microbial flora. Ovaries The ovaries are the female gonads (see Figure 27.9 ). Paired ovals, they are each about 2 to 3 cm in length, about the size of an almond. The ovaries are located within the pelvic cavity, and are supported by the mesovarium, an extension of the peritoneum that connects the ovaries to the broad ligament . Extending from the mesovarium itself is the suspensory ligament that contains the ovarian blood and lymph vessels. Finally, the ovary itself is attached to the uterus via the ovarian ligament. The ovary comprises an outer covering of cuboidal epithelium called the ovarian surface epithelium that is superficial to a dense connective tissue covering called the tunica albuginea. Beneath the tunica albuginea is the cortex, or outer portion, of the organ. The cortex is composed of a tissue framework called the ovarian stroma that forms the bulk of the adult ovary. Oocytes develop within the outer layer of this stroma, each surrounded by supporting cells. This grouping of an oocyte and its supporting cells is called a follicle . The growth and development of ovarian follicles will be described shortly. Beneath the cortex lies the inner ovarian medulla, the site of blood vessels, lymph vessels, and the nerves of the ovary. You will learn more about the overall anatomy of the female reproductive system at the end of this section. The Ovarian Cycle The ovarian cycle is a set of predictable changes in a female’s oocytes and ovarian follicles. During a woman’s reproductive years, it is a roughly 28-day cycle that can be correlated with, but is not the same as, the menstrual cycle (discussed shortly). The cycle includes two interrelated processes: oogenesis (the production of female gametes) and folliculogenesis (the growth and development of ovarian follicles). Oogenesis Gametogenesis in females is called oogenesis . The process begins with the ovarian stem cells, or oogonia ( Figure 27.11 ). Oogonia are formed during fetal development, and divide via mitosis, much like spermatogonia in the testis. Unlike spermatogonia, however, oogonia form primary oocytes in the fetal ovary prior to birth. These primary oocytes are then arrested in this stage of meiosis I, only to resume it years later, beginning at puberty and continuing until the woman is near menopause (the cessation of a woman’s reproductive functions). The number of primary oocytes present in the ovaries declines from one to two million in an infant, to approximately 400,000 at puberty, to zero by the end of menopause. The initiation of ovulation —the release of an oocyte from the ovary—marks the transition from puberty into reproductive maturity for women. From then on, throughout a woman’s reproductive years, ovulation occurs approximately once every 28 days. Just prior to ovulation, a surge of luteinizing hormone triggers the resumption of meiosis in a primary oocyte. This initiates the transition from primary to secondary oocyte. However, as you can see in Figure 27.11 , this cell division does not result in two identical cells. Instead, the cytoplasm is divided unequally, and one daughter cell is much larger than the other. This larger cell, the secondary oocyte, eventually leaves the ovary during ovulation. The smaller cell, called the first polar body , may or may not complete meiosis and produce second polar bodies; in either case, it eventually disintegrates. Therefore, even though oogenesis produces up to four cells, only one survives. How does the diploid secondary oocyte become an ovum —the haploid female gamete? Meiosis of a secondary oocyte is completed only if a sperm succeeds in penetrating its barriers. Meiosis II then resumes, producing one haploid ovum that, at the instant of fertilization by a (haploid) sperm, becomes the first diploid cell of the new offspring (a zygote). Thus, the ovum can be thought of as a brief, transitional, haploid stage between the diploid oocyte and diploid zygote. The larger amount of cytoplasm contained in the female gamete is used to supply the developing zygote with nutrients during the period between fertilization and implantation into the uterus. Interestingly, sperm contribute only DNA at fertilization —not cytoplasm. Therefore, the cytoplasm and all of the cytoplasmic organelles in the developing embryo are of maternal origin. This includes mitochondria, which contain their own DNA. Scientific research in the 1980s determined that mitochondrial DNA was maternally inherited, meaning that you can trace your mitochondrial DNA directly to your mother, her mother, and so on back through your female ancestors. Everyday Connection Mapping Human History with Mitochondrial DNA When we talk about human DNA, we’re usually referring to nuclear DNA; that is, the DNA coiled into chromosomal bundles in the nucleus of our cells. We inherit half of our nuclear DNA from our father, and half from our mother. However, mitochondrial DNA (mtDNA) comes only from the mitochondria in the cytoplasm of the fat ovum we inherit from our mother. She received her mtDNA from her mother, who got it from her mother, and so on. Each of our cells contains approximately 1700 mitochondria, with each mitochondrion packed with mtDNA containing approximately 37 genes. Mutations (changes) in mtDNA occur spontaneously in a somewhat organized pattern at regular intervals in human history. By analyzing these mutational relationships, researchers have been able to determine that we can all trace our ancestry back to one woman who lived in Africa about 200,000 years ago. Scientists have given this woman the biblical name Eve, although she is not, of course, the first Homo sapiens female. More precisely, she is our most recent common ancestor through matrilineal descent. This doesn’t mean that everyone’s mtDNA today looks exactly like that of our ancestral Eve. Because of the spontaneous mutations in mtDNA that have occurred over the centuries, researchers can map different “branches” off of the “main trunk” of our mtDNA family tree. Your mtDNA might have a pattern of mutations that aligns more closely with one branch, and your neighbor’s may align with another branch. Still, all branches eventually lead back to Eve. But what happened to the mtDNA of all of the other Homo sapiens females who were living at the time of Eve? Researchers explain that, over the centuries, their female descendants died childless or with only male children, and thus, their maternal line—and its mtDNA—ended. Folliculogenesis Again, ovarian follicles are oocytes and their supporting cells. They grow and develop in a process called folliculogenesis , which typically leads to ovulation of one follicle approximately every 28 days, along with death to multiple other follicles. The death of ovarian follicles is called atresia, and can occur at any point during follicular development. Recall that, a female infant at birth will have one to two million oocytes within her ovarian follicles, and that this number declines throughout life until menopause, when no follicles remain. As you’ll see next, follicles progress from primordial, to primary, to secondary and tertiary stages prior to ovulation—with the oocyte inside the follicle remaining as a primary oocyte until right before ovulation. Folliculogenesis begins with follicles in a resting state. These small primordial follicles are present in newborn females and are the prevailing follicle type in the adult ovary ( Figure 27.12 ). Primordial follicles have only a single flat layer of support cells, called granulosa cells , that surround the oocyte, and they can stay in this resting state for years—some until right before menopause. After puberty, a few primordial follicles will respond to a recruitment signal each day, and will join a pool of immature growing follicles called primary follicles . Primary follicles start with a single layer of granulosa cells, but the granulosa cells then become active and transition from a flat or squamous shape to a rounded, cuboidal shape as they increase in size and proliferate. As the granulosa cells divide, the follicles—now called secondary follicles (see Figure 27.12 )—increase in diameter, adding a new outer layer of connective tissue, blood vessels, and theca cells —cells that work with the granulosa cells to produce estrogens. Within the growing secondary follicle, the primary oocyte now secretes a thin acellular membrane called the zona pellucida that will play a critical role in fertilization. A thick fluid, called follicular fluid, that has formed between the granulosa cells also begins to collect into one large pool, or antrum . Follicles in which the antrum has become large and fully formed are considered tertiary follicles (or antral follicles). Several follicles reach the tertiary stage at the same time, and most of these will undergo atresia. The one that does not die will continue to grow and develop until ovulation, when it will expel its secondary oocyte surrounded by several layers of granulosa cells from the ovary. Keep in mind that most follicles don’t make it to this point. In fact, roughly 99 percent of the follicles in the ovary will undergo atresia, which can occur at any stage of folliculogenesis. Hormonal Control of the Ovarian Cycle The process of development that we have just described, from primordial follicle to early tertiary follicle, takes approximately two months in humans. The final stages of development of a small cohort of tertiary follicles, ending with ovulation of a secondary oocyte, occur over a course of approximately 28 days. These changes are regulated by many of the same hormones that regulate the male reproductive system, including GnRH, LH, and FSH. As in men, the hypothalamus produces GnRH, a hormone that signals the anterior pituitary gland to produce the gonadotropins FSH and LH ( Figure 27.13 ). These gonadotropins leave the pituitary and travel through the bloodstream to the ovaries, where they bind to receptors on the granulosa and theca cells of the follicles. FSH stimulates the follicles to grow (hence its name of follicle-stimulating hormone), and the five or six tertiary follicles expand in diameter. The release of LH also stimulates the granulosa and theca cells of the follicles to produce the sex steroid hormone estradiol, a type of estrogen. This phase of the ovarian cycle, when the tertiary follicles are growing and secreting estrogen, is known as the follicular phase. The more granulosa and theca cells a follicle has (that is, the larger and more developed it is), the more estrogen it will produce in response to LH stimulation. As a result of these large follicles producing large amounts of estrogen, systemic plasma estrogen concentrations increase. Following a classic negative feedback loop, the high concentrations of estrogen will stimulate the hypothalamus and pituitary to reduce the production of GnRH, LH, and FSH. Because the large tertiary follicles require FSH to grow and survive at this point, this decline in FSH caused by negative feedback leads most of them to die (atresia). Typically only one follicle, now called the dominant follicle, will survive this reduction in FSH, and this follicle will be the one that releases an oocyte. Scientists have studied many factors that lead to a particular follicle becoming dominant: size, the number of granulosa cells, and the number of FSH receptors on those granulosa cells all contribute to a follicle becoming the one surviving dominant follicle. When only the one dominant follicle remains in the ovary, it again begins to secrete estrogen. It produces more estrogen than all of the developing follicles did together before the negative feedback occurred. It produces so much estrogen that the normal negative feedback doesn’t occur. Instead, these extremely high concentrations of systemic plasma estrogen trigger a regulatory switch in the anterior pituitary that responds by secreting large amounts of LH and FSH into the bloodstream (see Figure 27.13 ). The positive feedback loop by which more estrogen triggers release of more LH and FSH only occurs at this point in the cycle. It is this large burst of LH (called the LH surge) that leads to ovulation of the dominant follicle. The LH surge induces many changes in the dominant follicle, including stimulating the resumption of meiosis of the primary oocyte to a secondary oocyte. As noted earlier, the polar body that results from unequal cell division simply degrades. The LH surge also triggers proteases (enzymes that cleave proteins) to break down structural proteins in the ovary wall on the surface of the bulging dominant follicle. This degradation of the wall, combined with pressure from the large, fluid-filled antrum, results in the expulsion of the oocyte surrounded by granulosa cells into the peritoneal cavity. This release is ovulation. In the next section, you will follow the ovulated oocyte as it travels toward the uterus, but there is one more important event that occurs in the ovarian cycle. The surge of LH also stimulates a change in the granulosa and theca cells that remain in the follicle after the oocyte has been ovulated. This change is called luteinization (recall that the full name of LH is luteinizing hormone), and it transforms the collapsed follicle into a new endocrine structure called the corpus luteum , a term meaning “yellowish body” (see Figure 27.12 ). Instead of estrogen, the luteinized granulosa and theca cells of the corpus luteum begin to produce large amounts of the sex steroid hormone progesterone, a hormone that is critical for the establishment and maintenance of pregnancy. Progesterone triggers negative feedback at the hypothalamus and pituitary, which keeps GnRH, LH, and FSH secretions low, so no new dominant follicles develop at this time. The post-ovulatory phase of progesterone secretion is known as the luteal phase of the ovarian cycle. If pregnancy does not occur within 10 to 12 days, the corpus luteum will stop secreting progesterone and degrade into the corpus albicans , a nonfunctional “whitish body” that will disintegrate in the ovary over a period of several months. During this time of reduced progesterone secretion, FSH and LH are once again stimulated, and the follicular phase begins again with a new cohort of early tertiary follicles beginning to grow and secrete estrogen. The Uterine Tubes The uterine tubes (also called fallopian tubes or oviducts) serve as the conduit of the oocyte from the ovary to the uterus ( Figure 27.14 ). Each of the two uterine tubes is close to, but not directly connected to, the ovary and divided into sections. The isthmus is the narrow medial end of each uterine tube that is connected to the uterus. The wide distal infundibulum flares out with slender, finger-like projections called fimbriae . The middle region of the tube, called the ampulla , is where fertilization often occurs. The uterine tubes also have three layers: an outer serosa, a middle smooth muscle layer, and an inner mucosal layer. In addition to its mucus-secreting cells, the inner mucosa contains ciliated cells that beat in the direction of the uterus, producing a current that will be critical to move the oocyte. Following ovulation, the secondary oocyte surrounded by a few granulosa cells is released into the peritoneal cavity. The nearby uterine tube, either left or right, receives the oocyte. Unlike sperm, oocytes lack flagella, and therefore cannot move on their own. So how do they travel into the uterine tube and toward the uterus? High concentrations of estrogen that occur around the time of ovulation induce contractions of the smooth muscle along the length of the uterine tube. These contractions occur every 4 to 8 seconds, and the result is a coordinated movement that sweeps the surface of the ovary and the pelvic cavity. Current flowing toward the uterus is generated by coordinated beating of the cilia that line the outside and lumen of the length of the uterine tube. These cilia beat more strongly in response to the high estrogen concentrations that occur around the time of ovulation. As a result of these mechanisms, the oocyte–granulosa cell complex is pulled into the interior of the tube. Once inside, the muscular contractions and beating cilia move the oocyte slowly toward the uterus. When fertilization does occur, sperm typically meet the egg while it is still moving through the ampulla. Interactive Link Watch this video to observe ovulation and its initiation in response to the release of FSH and LH from the pituitary gland. What specialized structures help guide the oocyte from the ovary into the uterine tube? If the oocyte is successfully fertilized, the resulting zygote will begin to divide into two cells, then four, and so on, as it makes its way through the uterine tube and into the uterus. There, it will implant and continue to grow. If the egg is not fertilized, it will simply degrade—either in the uterine tube or in the uterus, where it may be shed with the next menstrual period. The open-ended structure of the uterine tubes can have significant health consequences if bacteria or other contagions enter through the vagina and move through the uterus, into the tubes, and then into the pelvic cavity. If this is left unchecked, a bacterial infection (sepsis) could quickly become life-threatening. The spread of an infection in this manner is of special concern when unskilled practitioners perform abortions in non-sterile conditions. Sepsis is also associated with sexually transmitted bacterial infections, especially gonorrhea and chlamydia. These increase a woman’s risk for pelvic inflammatory disease (PID), infection of the uterine tubes or other reproductive organs. Even when resolved, PID can leave scar tissue in the tubes, leading to infertility. Interactive Link Watch this series of videos to look at the movement of the oocyte through the ovary. The cilia in the uterine tube promote movement of the oocyte. What would likely occur if the cilia were paralyzed at the time of ovulation? The Uterus and Cervix The uterus is the muscular organ that nourishes and supports the growing embryo (see Figure 27.14 ). Its average size is approximately 5 cm wide by 7 cm long (approximately 2 in by 3 in) when a female is not pregnant. It has three sections. The portion of the uterus superior to the opening of the uterine tubes is called the fundus . The middle section of the uterus is called the body of uterus (or corpus). The cervix is the narrow inferior portion of the uterus that projects into the vagina. The cervix produces mucus secretions that become thin and stringy under the influence of high systemic plasma estrogen concentrations, and these secretions can facilitate sperm movement through the reproductive tract. Several ligaments maintain the position of the uterus within the abdominopelvic cavity. The broad ligament is a fold of peritoneum that serves as a primary support for the uterus, extending laterally from both sides of the uterus and attaching it to the pelvic wall. The round ligament attaches to the uterus near the uterine tubes, and extends to the labia majora. Finally, the uterosacral ligament stabilizes the uterus posteriorly by its connection from the cervix to the pelvic wall. The wall of the uterus is made up of three layers. The most superficial layer is the serous membrane, or perimetrium , which consists of epithelial tissue that covers the exterior portion of the uterus. The middle layer, or myometrium , is a thick layer of smooth muscle responsible for uterine contractions. Most of the uterus is myometrial tissue, and the muscle fibers run horizontally, vertically, and diagonally, allowing the powerful contractions that occur during labor and the less powerful contractions (or cramps) that help to expel menstrual blood during a woman’s period. Anteriorly directed myometrial contractions also occur near the time of ovulation, and are thought to possibly facilitate the transport of sperm through the female reproductive tract. The innermost layer of the uterus is called the endometrium . The endometrium contains a connective tissue lining, the lamina propria, which is covered by epithelial tissue that lines the lumen. Structurally, the endometrium consists of two layers: the stratum basalis and the stratum functionalis (the basal and functional layers). The stratum basalis layer is part of the lamina propria and is adjacent to the myometrium; this layer does not shed during menses. In contrast, the thicker stratum functionalis layer contains the glandular portion of the lamina propria and the endothelial tissue that lines the uterine lumen. It is the stratum functionalis that grows and thickens in response to increased levels of estrogen and progesterone. In the luteal phase of the menstrual cycle, special branches off of the uterine artery called spiral arteries supply the thickened stratum functionalis. This inner functional layer provides the proper site of implantation for the fertilized egg, and—should fertilization not occur—it is only the stratum functionalis layer of the endometrium that sheds during menstruation. Recall that during the follicular phase of the ovarian cycle, the tertiary follicles are growing and secreting estrogen. At the same time, the stratum functionalis of the endometrium is thickening to prepare for a potential implantation. The post-ovulatory increase in progesterone, which characterizes the luteal phase, is key for maintaining a thick stratum functionalis. As long as a functional corpus luteum is present in the ovary, the endometrial lining is prepared for implantation. Indeed, if an embryo implants, signals are sent to the corpus luteum to continue secreting progesterone to maintain the endometrium, and thus maintain the pregnancy. If an embryo does not implant, no signal is sent to the corpus luteum and it degrades, ceasing progesterone production and ending the luteal phase. Without progesterone, the endometrium thins and, under the influence of prostaglandins, the spiral arteries of the endometrium constrict and rupture, preventing oxygenated blood from reaching the endometrial tissue. As a result, endometrial tissue dies and blood, pieces of the endometrial tissue, and white blood cells are shed through the vagina during menstruation, or the menses . The first menses after puberty, called menarche , can occur either before or after the first ovulation. The Menstrual Cycle Now that we have discussed the maturation of the cohort of tertiary follicles in the ovary, the build-up and then shedding of the endometrial lining in the uterus, and the function of the uterine tubes and vagina, we can put everything together to talk about the three phases of the menstrual cycle —the series of changes in which the uterine lining is shed, rebuilds, and prepares for implantation. The timing of the menstrual cycle starts with the first day of menses, referred to as day one of a woman’s period. Cycle length is determined by counting the days between the onset of bleeding in two subsequent cycles. Because the average length of a woman’s menstrual cycle is 28 days, this is the time period used to identify the timing of events in the cycle. However, the length of the menstrual cycle varies among women, and even in the same woman from one cycle to the next, typically from 21 to 32 days. Just as the hormones produced by the granulosa and theca cells of the ovary “drive” the follicular and luteal phases of the ovarian cycle, they also control the three distinct phases of the menstrual cycle. These are the menses phase, the proliferative phase, and the secretory phase. Menses Phase The menses phase of the menstrual cycle is the phase during which the lining is shed; that is, the days that the woman menstruates. Although it averages approximately five days, the menses phase can last from 2 to 7 days, or longer. As shown in Figure 27.15 , the menses phase occurs during the early days of the follicular phase of the ovarian cycle, when progesterone, FSH, and LH levels are low. Recall that progesterone concentrations decline as a result of the degradation of the corpus luteum, marking the end of the luteal phase. This decline in progesterone triggers the shedding of the stratum functionalis of the endometrium. Proliferative Phase Once menstrual flow ceases, the endometrium begins to proliferate again, marking the beginning of the proliferative phase of the menstrual cycle (see Figure 27.15 ). It occurs when the granulosa and theca cells of the tertiary follicles begin to produce increased amounts of estrogen. These rising estrogen concentrations stimulate the endometrial lining to rebuild. Recall that the high estrogen concentrations will eventually lead to a decrease in FSH as a result of negative feedback, resulting in atresia of all but one of the developing tertiary follicles. The switch to positive feedback—which occurs with the elevated estrogen production from the dominant follicle—then stimulates the LH surge that will trigger ovulation. In a typical 28-day menstrual cycle, ovulation occurs on day 14. Ovulation marks the end of the proliferative phase as well as the end of the follicular phase. Secretory Phase In addition to prompting the LH surge, high estrogen levels increase the uterine tube contractions that facilitate the pick-up and transfer of the ovulated oocyte. High estrogen levels also slightly decrease the acidity of the vagina, making it more hospitable to sperm. In the ovary, the luteinization of the granulosa cells of the collapsed follicle forms the progesterone-producing corpus luteum, marking the beginning of the luteal phase of the ovarian cycle. In the uterus, progesterone from the corpus luteum begins the secretory phase of the menstrual cycle, in which the endometrial lining prepares for implantation (see Figure 27.15 ). Over the next 10 to 12 days, the endometrial glands secrete a fluid rich in glycogen. If fertilization has occurred, this fluid will nourish the ball of cells now developing from the zygote. At the same time, the spiral arteries develop to provide blood to the thickened stratum functionalis. If no pregnancy occurs within approximately 10 to 12 days, the corpus luteum will degrade into the corpus albicans. Levels of both estrogen and progesterone will fall, and the endometrium will grow thinner. Prostaglandins will be secreted that cause constriction of the spiral arteries, reducing oxygen supply. The endometrial tissue will die, resulting in menses—or the first day of the next cycle. Disorders of the... Female Reproductive System Research over many years has confirmed that cervical cancer is most often caused by a sexually transmitted infection with human papillomavirus (HPV). There are over 100 related viruses in the HPV family, and the characteristics of each strain determine the outcome of the infection. In all cases, the virus enters body cells and uses its own genetic material to take over the host cell’s metabolic machinery and produce more virus particles. HPV infections are common in both men and women. Indeed, a recent study determined that 42.5 percent of females had HPV at the time of testing. These women ranged in age from 14 to 59 years and differed in race, ethnicity, and number of sexual partners. Of note, the prevalence of HPV infection was 53.8 percent among women aged 20 to 24 years, the age group with the highest infection rate. HPV strains are classified as high or low risk according to their potential to cause cancer. Though most HPV infections do not cause disease, the disruption of normal cellular functions in the low-risk forms of HPV can cause the male or female human host to develop genital warts. Often, the body is able to clear an HPV infection by normal immune responses within 2 years. However, the more serious, high-risk infection by certain types of HPV can result in cancer of the cervix ( Figure 27.16 ). Infection with either of the cancer-causing variants HPV 16 or HPV 18 has been linked to more than 70 percent of all cervical cancer diagnoses. Although even these high-risk HPV strains can be cleared from the body over time, infections persist in some individuals. If this happens, the HPV infection can influence the cells of the cervix to develop precancerous changes. Risk factors for cervical cancer include having unprotected sex; having multiple sexual partners; a first sexual experience at a younger age, when the cells of the cervix are not fully mature; failure to receive the HPV vaccine; a compromised immune system; and smoking. The risk of developing cervical cancer is doubled with cigarette smoking. When the high-risk types of HPV enter a cell, two viral proteins are used to neutralize proteins that the host cells use as checkpoints in the cell cycle. The best studied of these proteins is p53. In a normal cell, p53 detects DNA damage in the cell’s genome and either halts the progression of the cell cycle—allowing time for DNA repair to occur—or initiates apoptosis. Both of these processes prevent the accumulation of mutations in a cell’s genome. High-risk HPV can neutralize p53, keeping the cell in a state in which fast growth is possible and impairing apoptosis, allowing mutations to accumulate in the cellular DNA. The prevalence of cervical cancer in the United States is very low because of regular screening exams called pap smears. Pap smears sample cells of the cervix, allowing the detection of abnormal cells. If pre-cancerous cells are detected, there are several highly effective techniques that are currently in use to remove them before they pose a danger. However, women in developing countries often do not have access to regular pap smears. As a result, these women account for as many as 80 percent of the cases of cervical cancer worldwide. In 2006, the first vaccine against the high-risk types of HPV was approved. There are now two HPV vaccines available: Gardasil ® and Cervarix ® . Whereas these vaccines were initially only targeted for women, because HPV is sexually transmitted, both men and women require vaccination for this approach to achieve its maximum efficacy. A recent study suggests that the HPV vaccine has cut the rates of HPV infection by the four targeted strains at least in half. Unfortunately, the high cost of manufacturing the vaccine is currently limiting access to many women worldwide. The Breasts Whereas the breasts are located far from the other female reproductive organs, they are considered accessory organs of the female reproductive system. The function of the breasts is to supply milk to an infant in a process called lactation. The external features of the breast include a nipple surrounded by a pigmented areola ( Figure 27.17 ), whose coloration may deepen during pregnancy. The areola is typically circular and can vary in size from 25 to 100 mm in diameter. The areolar region is characterized by small, raised areolar glands that secrete lubricating fluid during lactation to protect the nipple from chafing. When a baby nurses, or draws milk from the breast, the entire areolar region is taken into the mouth. Breast milk is produced by the mammary glands , which are modified sweat glands. The milk itself exits the breast through the nipple via 15 to 20 lactiferous ducts that open on the surface of the nipple. These lactiferous ducts each extend to a lactiferous sinus that connects to a glandular lobe within the breast itself that contains groups of milk-secreting cells in clusters called alveoli (see Figure 27.17 ). The clusters can change in size depending on the amount of milk in the alveolar lumen. Once milk is made in the alveoli, stimulated myoepithelial cells that surround the alveoli contract to push the milk to the lactiferous sinuses. From here, the baby can draw milk through the lactiferous ducts by suckling. The lobes themselves are surrounded by fat tissue, which determines the size of the breast; breast size differs between individuals and does not affect the amount of milk produced. Supporting the breasts are multiple bands of connective tissue called suspensory ligaments that connect the breast tissue to the dermis of the overlying skin. During the normal hormonal fluctuations in the menstrual cycle, breast tissue responds to changing levels of estrogen and progesterone, which can lead to swelling and breast tenderness in some individuals, especially during the secretory phase. If pregnancy occurs, the increase in hormones leads to further development of the mammary tissue and enlargement of the breasts. Hormonal Birth Control Birth control pills take advantage of the negative feedback system that regulates the ovarian and menstrual cycles to stop ovulation and prevent pregnancy. Typically they work by providing a constant level of both estrogen and progesterone, which negatively feeds back onto the hypothalamus and pituitary, thus preventing the release of FSH and LH. Without FSH, the follicles do not mature, and without the LH surge, ovulation does not occur. Although the estrogen in birth control pills does stimulate some thickening of the endometrial wall, it is reduced compared with a normal cycle and is less likely to support implantation. Some birth control pills contain 21 active pills containing hormones, and 7 inactive pills (placebos). The decline in hormones during the week that the woman takes the placebo pills triggers menses, although it is typically lighter than a normal menstrual flow because of the reduced endometrial thickening. Newer types of birth control pills have been developed that deliver low-dose estrogens and progesterone for the entire cycle (these are meant to be taken 365 days a year), and menses never occurs. While some women prefer to have the proof of a lack of pregnancy that a monthly period provides, menstruation every 28 days is not required for health reasons, and there are no reported adverse effects of not having a menstrual period in an otherwise healthy individual. Because birth control pills function by providing constant estrogen and progesterone levels and disrupting negative feedback, skipping even just one or two pills at certain points of the cycle (or even being several hours late taking the pill) can lead to an increase in FSH and LH and result in ovulation. It is important, therefore, that the woman follow the directions on the birth control pill package to successfully prevent pregnancy. Aging and the... Female Reproductive System Female fertility (the ability to conceive) peaks when women are in their twenties, and is slowly reduced until a women reaches 35 years of age. After that time, fertility declines more rapidly, until it ends completely at the end of menopause. Menopause is the cessation of the menstrual cycle that occurs as a result of the loss of ovarian follicles and the hormones that they produce. A woman is considered to have completed menopause if she has not menstruated in a full year. After that point, she is considered postmenopausal. The average age for this change is consistent worldwide at between 50 and 52 years of age, but it can normally occur in a woman’s forties, or later in her fifties. Poor health, including smoking, can lead to earlier loss of fertility and earlier menopause. As a woman reaches the age of menopause, depletion of the number of viable follicles in the ovaries due to atresia affects the hormonal regulation of the menstrual cycle. During the years leading up to menopause, there is a decrease in the levels of the hormone inhibin, which normally participates in a negative feedback loop to the pituitary to control the production of FSH. The menopausal decrease in inhibin leads to an increase in FSH. The presence of FSH stimulates more follicles to grow and secrete estrogen. Because small, secondary follicles also respond to increases in FSH levels, larger numbers of follicles are stimulated to grow; however, most undergo atresia and die. Eventually, this process leads to the depletion of all follicles in the ovaries, and the production of estrogen falls off dramatically. It is primarily the lack of estrogens that leads to the symptoms of menopause. The earliest changes occur during the menopausal transition, often referred to as peri-menopause, when a women’s cycle becomes irregular but does not stop entirely. Although the levels of estrogen are still nearly the same as before the transition, the level of progesterone produced by the corpus luteum is reduced. This decline in progesterone can lead to abnormal growth, or hyperplasia, of the endometrium. This condition is a concern because it increases the risk of developing endometrial cancer. Two harmless conditions that can develop during the transition are uterine fibroids, which are benign masses of cells, and irregular bleeding. As estrogen levels change, other symptoms that occur are hot flashes and night sweats, trouble sleeping, vaginal dryness, mood swings, difficulty focusing, and thinning of hair on the head along with the growth of more hair on the face. Depending on the individual, these symptoms can be entirely absent, moderate, or severe. After menopause, lower amounts of estrogens can lead to other changes. Cardiovascular disease becomes as prevalent in women as in men, possibly because estrogens reduce the amount of cholesterol in the blood vessels. When estrogen is lacking, many women find that they suddenly have problems with high cholesterol and the cardiovascular issues that accompany it. Osteoporosis is another problem because bone density decreases rapidly in the first years after menopause. The reduction in bone density leads to a higher incidence of fractures. Hormone therapy (HT), which employs medication (synthetic estrogens and progestins) to increase estrogen and progestin levels, can alleviate some of the symptoms of menopause. In 2002, the Women’s Health Initiative began a study to observe women for the long-term outcomes of hormone replacement therapy over 8.5 years. However, the study was prematurely terminated after 5.2 years because of evidence of a higher than normal risk of breast cancer in patients taking estrogen-only HT. The potential positive effects on cardiovascular disease were also not realized in the estrogen-only patients. The results of other hormone replacement studies over the last 50 years, including a 2012 study that followed over 1,000 menopausal women for 10 years, have shown cardiovascular benefits from estrogen and no increased risk for cancer. Some researchers believe that the age group tested in the 2002 trial may have been too old to benefit from the therapy, thus skewing the results. In the meantime, intense debate and study of the benefits and risks of replacement therapy is ongoing. Current guidelines approve HT for the reduction of hot flashes or flushes, but this treatment is generally only considered when women first start showing signs of menopausal changes, is used in the lowest dose possible for the shortest time possible (5 years or less), and it is suggested that women on HT have regular pelvic and breast exams. 27.3 Development of the Male and Female Reproductive Systems Learning Objectives By the end of this section, you will be able to: Explain how bipotential tissues are directed to develop into male or female sex organs Name the rudimentary duct systems in the embryo that are precursors to male or female internal sex organs Describe the hormonal changes that bring about puberty, and the secondary sex characteristics of men and women The development of the reproductive systems begins soon after fertilization of the egg, with primordial gonads beginning to develop approximately one month after conception. Reproductive development continues in utero, but there is little change in the reproductive system between infancy and puberty. Development of the Sexual Organs in the Embryo and Fetus Females are considered the “fundamental” sex—that is, without much chemical prompting, all fertilized eggs would develop into females. To become a male, an individual must be exposed to the cascade of factors initiated by a single gene on the male Y chromosome. This is called the SRY ( S ex-determining R egion of the Y chromosome). Because females do not have a Y chromosome, they do not have the SRY gene. Without a functional SRY gene, an individual will be female. In both male and female embryos, the same group of cells has the potential to develop into either the male or female gonads; this tissue is considered bipotential. The SRY gene actively recruits other genes that begin to develop the testes, and suppresses genes that are important in female development. As part of this SRY -prompted cascade, germ cells in the bipotential gonads differentiate into spermatogonia. Without SRY , different genes are expressed, oogonia form, and primordial follicles develop in the primitive ovary. Soon after the formation of the testis, the Leydig cells begin to secrete testosterone. Testosterone can influence tissues that are bipotential to become male reproductive structures. For example, with exposure to testosterone, cells that could become either the glans penis or the glans clitoris form the glans penis. Without testosterone, these same cells differentiate into the clitoris. Not all tissues in the reproductive tract are bipotential. The internal reproductive structures (for example the uterus, uterine tubes, and part of the vagina in females; and the epididymis, ductus deferens, and seminal vesicles in males) form from one of two rudimentary duct systems in the embryo. For proper reproductive function in the adult, one set of these ducts must develop properly, and the other must degrade. In males, secretions from sustentacular cells trigger a degradation of the female duct, called the Müllerian duct . At the same time, testosterone secretion stimulates growth of the male tract, the Wolffian duct . Without such sustentacular cell secretion, the Müllerian duct will develop; without testosterone, the Wolffian duct will degrade. Thus, the developing offspring will be female. For more information and a figure of differentiation of the gonads, seek additional content on fetal development. Interactive Link A baby’s gender is determined at conception, and the different genitalia of male and female fetuses develop from the same tissues in the embryo. View this animation to see a comparison of the development of structures of the female and male reproductive systems in a growing fetus. Where are the testes located for most of gestational time? Further Sexual Development Occurs at Puberty Puberty is the stage of development at which individuals become sexually mature. Though the outcomes of puberty for boys and girls are very different, the hormonal control of the process is very similar. In addition, though the timing of these events varies between individuals, the sequence of changes that occur is predictable for male and female adolescents. As shown in Figure 27.18 , a concerted release of hormones from the hypothalamus (GnRH), the anterior pituitary (LH and FSH), and the gonads (either testosterone or estrogen) is responsible for the maturation of the reproductive systems and the development of secondary sex characteristics , which are physical changes that serve auxiliary roles in reproduction. The first changes begin around the age of eight or nine when the production of LH becomes detectable. The release of LH occurs primarily at night during sleep and precedes the physical changes of puberty by several years. In pre-pubertal children, the sensitivity of the negative feedback system in the hypothalamus and pituitary is very high. This means that very low concentrations of androgens or estrogens will negatively feed back onto the hypothalamus and pituitary, keeping the production of GnRH, LH, and FSH low. As an individual approaches puberty, two changes in sensitivity occur. The first is a decrease of sensitivity in the hypothalamus and pituitary to negative feedback, meaning that it takes increasingly larger concentrations of sex steroid hormones to stop the production of LH and FSH. The second change in sensitivity is an increase in sensitivity of the gonads to the FSH and LH signals, meaning the gonads of adults are more responsive to gonadotropins than are the gonads of children. As a result of these two changes, the levels of LH and FSH slowly increase and lead to the enlargement and maturation of the gonads, which in turn leads to secretion of higher levels of sex hormones and the initiation of spermatogenesis and folliculogenesis. In addition to age, multiple factors can affect the age of onset of puberty, including genetics, environment, and psychological stress. One of the more important influences may be nutrition; historical data demonstrate the effect of better and more consistent nutrition on the age of menarche in girls in the United States, which decreased from an average age of approximately 17 years of age in 1860 to the current age of approximately 12.75 years in 1960, as it remains today. Some studies indicate a link between puberty onset and the amount of stored fat in an individual. This effect is more pronounced in girls, but has been documented in both sexes. Body fat, corresponding with secretion of the hormone leptin by adipose cells, appears to have a strong role in determining menarche. This may reflect to some extent the high metabolic costs of gestation and lactation. In girls who are lean and highly active, such as gymnasts, there is often a delay in the onset of puberty. Signs of Puberty Different sex steroid hormone concentrations between the sexes also contribute to the development and function of secondary sexual characteristics. Examples of secondary sexual characteristics are listed in Table 27.1 . Development of the Secondary Sexual Characteristics Male Female Increased larynx size and deepening of the voice Deposition of fat, predominantly in breasts and hips Increased muscular development Breast development Growth of facial, axillary, and pubic hair, and increased growth of body hair Broadening of the pelvis and growth of axillary and pubic hair Table 27.1 As a girl reaches puberty, typically the first change that is visible is the development of the breast tissue. This is followed by the growth of axillary and pubic hair. A growth spurt normally starts at approximately age 9 to 11, and may last two years or more. During this time, a girl’s height can increase 3 inches a year. The next step in puberty is menarche, the start of menstruation. In boys, the growth of the testes is typically the first physical sign of the beginning of puberty, which is followed by growth and pigmentation of the scrotum and growth of the penis. The next step is the growth of hair, including armpit, pubic, chest, and facial hair. Testosterone stimulates the growth of the larynx and thickening and lengthening of the vocal folds, which causes the voice to drop in pitch. The first fertile ejaculations typically appear at approximately 15 years of age, but this age can vary widely across individual boys. Unlike the early growth spurt observed in females, the male growth spurt occurs toward the end of puberty, at approximately age 11 to 13, and a boy’s height can increase as much as 4 inches a year. In some males, pubertal development can continue through the early 20s.
business_law_i_essentials
Chapter Outline 3.1 Business Ethics 3.2 Social Responsibility Introduction Learning Outcome Analyze the role of ethics and social responsibility in business.
[ { "answer": { "ans_choice": 2, "ans_text": "Leadership." }, "bloom": null, "hl_context": "<hl> The idea of business ethics may seem subjective , but it comes down to acceptable levels of behavior for each individual who makes up the organization . <hl> <hl> This behavior must start at the top with responsible actions demonstrated by leadership . <hl> By doing so , leaders create a set of rules that are to be followed by others in the company . These rules can be based on the deep values that the company has concerning the quality of products and services , the commitment to customers , or how the organization gives something back to the community . The more a company lives by its set of ethics , the more likely it is to be successful .", "hl_sentences": "The idea of business ethics may seem subjective , but it comes down to acceptable levels of behavior for each individual who makes up the organization . This behavior must start at the top with responsible actions demonstrated by leadership .", "question": { "cloze_format": "___ decide the business ethics for a company.", "normal_format": "Who decides the business ethics for a company?", "question_choices": [ "The HR department.", "The employees.", "Leadership.", "Consultants." ], "question_id": "fs-2123", "question_text": "Who decides the business ethics for a company?" }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 1, "ans_text": "b" }, "bloom": null, "hl_context": "<hl> Company credibility lost . <hl> Customers are savvy enough to follow what ’ s going on from an ethics standpoint . If they hear of a problem , they begin to question the actions of every person at the company . For example , if a member of the board is accepting expensive gifts from clients in exchange for favorable pricing of materials , this situation could set off major alarms for other customers , and even vendors . The company can expect to lose business if this unethical behavior continues . <hl> Recruitment and retention problems . <hl> Once a company has developed a negative reputation , it can be difficult to recruit new talent , let alone retain the talent that ’ s already there . Disengaged employees who grow tired of the double standards will leave . This attrition can impact customers who then have to deal with less experienced and less interested employees , who are already overworked and frustrated . <hl> Negative employee relations . <hl> If employees continually see a discrepancy between what ’ s expected of them and how leadership behaves , this contrast can create serious problems in the management of employees . Some employees may become disengaged , while others will stop working as hard . After all , if the same rules don ’ t apply to everyone , why even bother ? The downside to negative employee relations is that the entire company becomes less productive , less responsive to customers , and less profitable . <hl> Poor company reputation . <hl> In an increasingly transparent world , unethical decisions made by businesspeople become permanent stains on the company . Social networks have become sounding boards for anything deemed unethical or politically incorrect , and everyone from disgruntled employees to dissatisfied customers can rate companies on public company review websites . <hl> Some possible results of unethical business actions may include : <hl>", "hl_sentences": "Company credibility lost . Recruitment and retention problems . Negative employee relations . Poor company reputation . Some possible results of unethical business actions may include :", "question": { "cloze_format": "All of the following are examples of results of unethical business actions except the ___ .", "normal_format": "Which of the following is NOT an example of the results of unethical business actions?", "question_choices": [ "Recruitment and retention problems.", "Lower employee salaries.", "Negative employee relations.", "Poor company reputation." ], "question_id": "fs-2124", "question_text": "All of the following are examples of results of unethical business actions except:" }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 3, "ans_text": "All of the above." }, "bloom": null, "hl_context": "The idea of business ethics may seem subjective , but it comes down to acceptable levels of behavior for each individual who makes up the organization . This behavior must start at the top with responsible actions demonstrated by leadership . By doing so , leaders create a set of rules that are to be followed by others in the company . <hl> These rules can be based on the deep values that the company has concerning the quality of products and services , the commitment to customers , or how the organization gives something back to the community . <hl> The more a company lives by its set of ethics , the more likely it is to be successful .", "hl_sentences": "These rules can be based on the deep values that the company has concerning the quality of products and services , the commitment to customers , or how the organization gives something back to the community .", "question": { "cloze_format": "Ethical rules can be based on deep values of an organization which may include ___ .", "normal_format": "Which deep values of an organization may the ethical rules be based on?", "question_choices": [ "Quality of products and services.", "Commitment to customers.", "How the organization gives back to the community.", "All of the above." ], "question_id": "fs-21241", "question_text": "Ethical rules can be based on deep values of an organization which may include:" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 0, "ans_text": "a" }, "bloom": null, "hl_context": "<hl> Professional behaviors . <hl> One should never assume that just because someone puts on a business suit and goes to work that he or she will behave professionally . Problems such as bullying , harassment , and abuse can happen in the workplace . Establishing behavioral standards for professionalism should include what is acceptable in the office , while traveling , during meetings , and after hours , when colleagues meet with clients and one another . <hl> Regulatory ethics . <hl> These are designed to maintain certain standards of performance based on the industry . One example is a commitment to maintaining data privacy at all times , as it pertains to customer records . This element defines how employees are to handle sensitive data and what will happen if someone doesn ’ t follow the rules . <hl> Value-based ethics . <hl> These are specific ethics that dig under the surface of a corporate culture . A business should think about how it wants to be viewed by the community . Examples could be a commitment to green office practices , reduction of a company ’ s carbon footprint , giving a certain percentage of a company ’ s profits to the local food pantry to support the community , etc . <hl> The elements that belong in a code of conduct , according to Kimberlee Leonard , are : <hl>", "hl_sentences": "Professional behaviors . Regulatory ethics . Value-based ethics . The elements that belong in a code of conduct , according to Kimberlee Leonard , are :", "question": { "cloze_format": "According to Kimberlee Leonard of the Houston Chronicle the elements that belong in a Code of Conduct for a company include all of the following except ___.", "normal_format": "Which of the following is NOT an element that belongs in a Code of Conduct for a company, according to Kimberlee Leonard of the Houston Chronicle?", "question_choices": [ "Office Hours.", "Professional behaviors.", "Regulatory ethics.", "Legal considerations." ], "question_id": "fs-212411", "question_text": "According to Kimberlee Leonard of the Houston Chronicle the elements that belong in a Code of Conduct for a company include all of the following except:" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 3, "ans_text": "All of the above." }, "bloom": null, "hl_context": "<hl> Consumer influence . <hl> A major benefit of engaging in corporate social responsibility efforts is that consumers regularly check in with their favorite brands to see what they are doing , and they are influenced to make purchases so they can be part of this community . With the process of posting messages on social networks , entire movements can take off via the support of loyal consumers . <hl> Talent attraction . <hl> Many companies offer employees paid time off to participate in volunteer activities , including travel to other nations . Who wouldn ’ t want to work for a company that cares so much about a personal cause ? Corporate social responsibility is often used as a recruitment tool to attract people who care about giving back to their communities and making changes that impact the world . <hl> Improved perception by investors . <hl> If a company reports corporate social responsibility spending that exceeds the expectations of investors , this dollar amount is a sign that the company itself is in good financial standing . This perception results in positive stock returns and increased confidence by investors . <hl> Benefits of corporate social responsibility include many direct and indirect effects . <hl> <hl> Based on research from the Kellogg School of Management at Northwestern University , these can include : <hl>", "hl_sentences": "Consumer influence . Talent attraction . Improved perception by investors . Benefits of corporate social responsibility include many direct and indirect effects . Based on research from the Kellogg School of Management at Northwestern University , these can include :", "question": { "cloze_format": "The benefits of Corporate Responsibility for a business include ___ .", "normal_format": "What are the benefits of Corporate Responsibility for a business?", "question_choices": [ "Talent attraction.", "Consumer influence.", "Improved perception by investors.", "All of the above." ], "question_id": "fs-21232", "question_text": "The benefits of Corporate Responsibility for a business include:" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 3, "ans_text": "d" }, "bloom": null, "hl_context": "When examining the value of corporate responsibility , one must understand the concept of the triple bottom line ( TBL ) , which essentially measures the sustainability of an organization ’ s social responsibility efforts . <hl> The term includes three dimensions of a giving business — profits , people , and the planet . <hl> Without one of these factors , there cannot be a balance . According to economist Andrew Savitz , the triple bottom line “ captures the essence of sustainability by measuring the impact of an organization ’ s activities on the world ... including both its profitability and shareholder values and its social , human and environmental capital . ”", "hl_sentences": "The term includes three dimensions of a giving business — profits , people , and the planet .", "question": { "cloze_format": "The three dimensions of the triple bottom line include all of the following except ___.", "normal_format": "Which of the following does not include in the three dimensions of the triple bottom line?", "question_choices": [ "Profits.", "People.", "Planet.", "Promotion." ], "question_id": "fs-212323", "question_text": "The three dimensions of the triple bottom line include all of the following except:" }, "references_are_paraphrase": null } ]
3
3.1 Business Ethics Businesses must establish a clear set of values that promote ethical practices and social responsibility. In today’s business climate, companies are increasingly under scrutiny by private citizens. A company that builds its foundation on sound principles will have a better chance of staying competitive in a volatile market. Business ethics are considered to be the blueprint for building a successful organization. If an organization is built on socially responsible values, it will be stronger than an organization that is built on profit alone. More than just a positive reputation, the core ethics of a business dictate how every decision, process, and procedure will take place. This steadfast governance applies even if the business faces hard times or difficult situations. Some will even argue that businesses require full transparency in today’s world. Over the last few decades, numerous cases of bad business practices have made headlines. From McDonalds’ funding of President Nixon’s campaign in an effort to reduce workers’ wages in the 1970s, to the more recent case of Uber employees alleging sexual harassment and the company’s CEO having a public meltdown in the back of a driver’s car, there’s no shortage of ethics-related problems in the business world. Businesses are more than people working together to offer a product or service. Businesses are often viewed as entities that should protect stakeholders from unethical behaviors and activities. A set of governing rules should be in place to set the bar high for ethical compliance in every organization. Why Is Corporate Ethics So Important in Business? The idea of business ethics may seem subjective, but it comes down to acceptable levels of behavior for each individual who makes up the organization. This behavior must start at the top with responsible actions demonstrated by leadership. By doing so, leaders create a set of rules that are to be followed by others in the company. These rules can be based on the deep values that the company has concerning the quality of products and services, the commitment to customers, or how the organization gives something back to the community. The more a company lives by its set of ethics, the more likely it is to be successful. Anna Spooner, who writes for LovetoKnow, shares tips on how to evaluate whether or not an organization is creating ethical practices by determining the impact of each practice. Some examples include: Executive compensation rates during employee layoffs. Let’s say a company is struggling during an economic downturn and must lay off a portion of its workforce. Does the CEO of the company take his or her annual raise or take a pay cut when others are losing their jobs? One could say that to take a raise is unethical because the CEO should also sacrifice some pay for the good of the company. Fair compensation for employees. Paying employees minimum wage, or just above minimum wage, is not always fair compensation. In most regions, the cost of living has not been adjusted in years, meaning that people are surviving on less money. Ethics can make a difference here. Ethical business practices, guided by a corporate set of standards, can have many positive outcomes, including recruitment and retention improvement, better relationships with customers, and positive PR. In 2015, Dan Price, CEO of the Seattle payment processing firm Gravity Payments, voluntarily took a huge pay cut and vowed to raise his employees’ wages to $70,000. This move was great for the company, which claims that revenues and profits skyrocketed, and they experienced a 91 percent employee retention rate over the last few years. On the opposite side, unethical business behaviors can have a negative impact on any business. Even if an unethical decision is made by a single member of the executive team, it can have far-reaching repercussions. Some possible results of unethical business actions may include: Poor company reputation. In an increasingly transparent world, unethical decisions made by businesspeople become permanent stains on the company. Social networks have become sounding boards for anything deemed unethical or politically incorrect, and everyone from disgruntled employees to dissatisfied customers can rate companies on public company review websites. Negative employee relations. If employees continually see a discrepancy between what’s expected of them and how leadership behaves, this contrast can create serious problems in the management of employees. Some employees may become disengaged, while others will stop working as hard. After all, if the same rules don’t apply to everyone, why even bother? The downside to negative employee relations is that the entire company becomes less productive, less responsive to customers, and less profitable. Recruitment and retention problems. Once a company has developed a negative reputation, it can be difficult to recruit new talent, let alone retain the talent that’s already there. Disengaged employees who grow tired of the double standards will leave. This attrition can impact customers who then have to deal with less experienced and less interested employees, who are already overworked and frustrated. Company credibility lost. Customers are savvy enough to follow what’s going on from an ethics standpoint. If they hear of a problem, they begin to question the actions of every person at the company. For example, if a member of the board is accepting expensive gifts from clients in exchange for favorable pricing of materials, this situation could set off major alarms for other customers, and even vendors. The company can expect to lose business if this unethical behavior continues. As you can see, poor ethics can quickly spiral downward, destroying every aspect of the business and making it very difficult to compete. It’s critical for every business to pay attention to ethical standards and continually remind employees at all levels that their behavior has an impact on the entire organization. History of Corporate Governance The concept of corporate governance is relatively new compared to the entire history of free trade and business formation. There was likely some “code of honor” followed by businesses in the past, but it wasn’t until the 21st century that greater attention was paid to how companies operate and how the operation impacts employees and the communities in which they serve. According to the Ethics and Compliance Initiative, which is comprised of organizations that are committed to creating best practices in ethics, each decade has been influenced by external factors, such as war or economic turmoil, combined with major ethical focal areas, and the result has been the development of ethics and compliance programs. For example, in the mid-1980s, the United States was thrust into a recessionary period. During this period, government contractors were billing outrageous amounts for equipment and services, further increasing the government’s deficit. At the same time, larger companies began downsizing to cut costs, which eroded the trust that employees once had. People felt the need to look out for themselves. Greed appeared to be everywhere, from political bribes to the earliest financial schemers. As a result, General Dynamics established the first business ethics office in 1985 to crack down on this kind of activity, and other companies created ombudsman positions to help ethics officers identify and prosecute corporate ethics violators. Ethical Decision-Making Policies In any organization, sound moral, business, and financial practices must be followed at all times. No one is above the law or has special privileges when it comes to ethics. Decision making needs to happen with corporate governance in mind. According to Michigan State University, the six steps to ethical decision making are: Make sure leaders understand the issue at hand and have gathered all of the facts related to it. Leaders should list all of the facts they know, and list any assumptions they are making about the issue. This step ensures that the leaders keep the facts and assumptions differentiated and in mind. Note all of the concerns related to the issue, including all of the people concerned, the laws related to the issue, and any corporate or professional ethical guidelines that may be involved. Construct a potential solution to the problem. Evaluate the proposed solution, making sure to consider all of the ethical aspects noted in step 3. Once leaders have come to a solution, they recommend it, as well as any actions that need to be taken. Establishing a Code of Conduct To educate and guide others in the organization, a set of ethics, or a code of conduct, should be developed and distributed. Kimberlee Leonard, who writes for the Houston Chronicle , states, “A code of ethics is important for businesses to establish to ensure that everyone in the company is clear on the mission, values and guiding principles of the company.” While it takes some time to create a code of conduct, the ideals involved should already be present in the company’s culture. The elements that belong in a code of conduct, according to Kimberlee Leonard, are: Legal considerations. The business is a legal entity, and therefore all employees should be thinking about their behavior and how it could easily turn into a lawsuit. Establishing conduct rules at this level can clear up any gray areas. For example, a company should define what sexual harassment is and what to do if an employee experiences it. New items that detail specific codes of conduct can be added as they come up. Value-based ethics. These are specific ethics that dig under the surface of a corporate culture. A business should think about how it wants to be viewed by the community. Examples could be a commitment to green office practices, reduction of a company’s carbon footprint, giving a certain percentage of a company’s profits to the local food pantry to support the community, etc. Regulatory ethics. These are designed to maintain certain standards of performance based on the industry. One example is a commitment to maintaining data privacy at all times, as it pertains to customer records. This element defines how employees are to handle sensitive data and what will happen if someone doesn’t follow the rules. Professional behaviors. One should never assume that just because someone puts on a business suit and goes to work that he or she will behave professionally. Problems such as bullying, harassment, and abuse can happen in the workplace. Establishing behavioral standards for professionalism should include what is acceptable in the office, while traveling, during meetings, and after hours, when colleagues meet with clients and one another. A good code of conduct is a working document that can be updated and shared as needed. Many companies include this document as part of their employee manual, while others use a secure intranet for displaying this information. No matter where it is housed, employees need to be educated on the code of conduct and refer to it often, starting on the first day on the job. What to Do When Something Goes Wrong It should be noted that along with a code of conduct, there needs to be a clear “whistleblower” policy in which violators are identified and action is taken. This process should be handled with complete confidentiality and sensitivity to the company and all parties involved. Retaliation should never be tolerated when it comes to ethics violations. The company should have a step-by-step plan of action for dealing with ethics problems at all levels, up to and including the executive leadership of the company. A third-party investigative firm can be used to handle such matters to remove the burden and influence that internal resources may have. 3.2 Social Responsibility Over the last few decades, there has been a movement throughout the global business community to improve the world through smarter use of resources and giving back to communities. This movement is called corporate social responsibility. The concept is catching on at companies that range in size from small startups to large Fortune 500 corporations. In the following section, you will learn what social responsibility is and how it is a win-win for businesses and consumers. What Is Corporate Responsibility? Corporate responsibility refers to the idea that a business is given the opportunity and privilege to make the world a better place. This process can happen through a variety of methods, including the donation of funds, volunteerism, and implementation of environmentally friendly policies. It is up to each organization to determine the best way to demonstrate social responsibility. While certainly not mandatory, corporate social responsibility has become a popular way for companies to improve their image and promote causes they believe in at the same time. Corporate social responsibility may involve focusing on the immediate community in which a company does business. However, there are some organizations that take it a step further and focus on more widespread global issues. For example, the shoe company TOMS has created a mission to make sure that every boy and girl in underprivileged countries has proper footwear. Blake Mycoskie, CEO of TOMS, has created a complete business model around social responsibility. Not stopping at shoes, the company now also helps with bringing fresh water to communities, as well as making birth safer for babies in developing nations. The popularity of corporate social responsibility has only increased as millennials and Generation Z employees enter the workforce. Employees in these generations often care deeply about making a difference in the world in which they work. Whether they are buying products from brands that give back or promoting a similar activity in their own place of employment, the youngest of the workforce are making corporate social responsibility a priority. Where Did the Concept Originate? Corporate social responsibility is not a new construct. One could go back hundreds of years and find examples of corporate philanthropy and social support. However, the earliest published book about the topic is Corporate Responsibility of the Businessman , published in 1953. This book introduced the concept of companies giving back as a form of investment in the future. This idea came from a generation that had survived some of the hardest times in our world and wanted to make it a better place for generations to come. By the turn of the millennium, companies were actively participating in a variety of corporate social responsibility projects, from volunteerism to large corporate-matched charitable donations. Nearly every company has some form of charitable campaign, driven by the values of the culture and the interests of employees. Today, some 63 million Americans volunteer each year, which is worth around $175 billion in worker hours annually (Source: Corporation for National and Community Service). On top of volunteering, U.S. corporations give over $18 billion to charities each year through fundraisers and employee-employer matching programs (Source: Giving USA). How Does Corporate Responsibility Benefit a Business? There are many ways that corporate social responsibility can benefit a business and its objectives. Aside from being able to promote the causes that are closely connected to the values of the company, a business can improve its reputation exponentially. Benefits of corporate social responsibility include many direct and indirect effects. Based on research from the Kellogg School of Management at Northwestern University, these can include: Improved perception by investors. If a company reports corporate social responsibility spending that exceeds the expectations of investors, this dollar amount is a sign that the company itself is in good financial standing. This perception results in positive stock returns and increased confidence by investors. Enhanced performance for going green. Researchers have found that when companies focus on eco-friendly efforts, the positive impact on operational performance heading into the second year is remarkable. Those that expand their efforts in more complex ways and in collaboration with industry standard-setting associations (such as LEED), or other eco-friendly companies, increase their performance even more. Contracting for success . In companies that tie their CEO’s salary to corporate social responsibility results, also known as contracting, the impact is felt even more. The value of the company increases while the bottom line of the business is maintained. The benevolent halo effect. When consumers understand the commitment that an organization has to being socially responsible, its image becomes more positive. Customers actually perceive the company and its products in a different way because they expect a better experience. Consistency of efforts and partnerships. Researchers also found that socially responsible organizations were consistent with staying focused on the issues that mattered most to their employees and customers. A higher level of consistency of efforts prompted better results. There are some other benefits of being a socially responsible company. These may happen as a result of internal factors, as well as how closely matched the efforts are to the culture. Alison Robins, writer for OfficeVibe, explains that being socially responsible can help attract positive attention from outside of a company. Some examples include: Talent attraction. Many companies offer employees paid time off to participate in volunteer activities, including travel to other nations. Who wouldn’t want to work for a company that cares so much about a personal cause? Corporate social responsibility is often used as a recruitment tool to attract people who care about giving back to their communities and making changes that impact the world. Consumer influence. A major benefit of engaging in corporate social responsibility efforts is that consumers regularly check in with their favorite brands to see what they are doing, and they are influenced to make purchases so they can be part of this community. With the process of posting messages on social networks, entire movements can take off via the support of loyal consumers. Promoting Corporate Responsibility with Marketing After reviewing the benefits of corporate social responsibility and some of the examples provided by popular companies, it is easy to see how important proper marketing can be to this effort. As you can see from the following example of Tom’s One for One™ program, marketing is used as a reminder for consumers that the company is committed to providing one pair of shoes to a child in an undeveloped nation for every pair purchased by a consumer. Marketing is powerful in terms of the consumer market. It has been estimated by the brand marketing news source Adweek that millennials represent around $2.45 trillion in spending per year. Cone Communications, a public relations and marketing agency, found that 60 percent more millennials will engage with brands that discuss and market to social issues. Younger consumers are attracted to brands that authentically market their products alongside social responsibility campaigns. However, one should not use corporate social responsibility as a marketing pitch for a company. Consumers will quickly pick up on this tactic, and it can damage the brand. Nicole Fallon, who contributes to Business News Daily , reveals, “The motivation behind many companies’ CSR efforts actually provides the very reason that they shouldn’t take on socially responsible initiatives.” Motivations such as competitive positioning and profitability are not authentic when it comes to corporate social responsibility. It is also important to distinguish between corporate social responsibility and social marketing. Often used interchangeably, there are some key differences. Social marketing attempts to change the attitudes and behaviors of consumers by using a variety of marketing methods. However, corporate social responsibility is a sustainable effort that can be measured. Bernard Okhakume, a brand management consultant, advised Daily Times , “For a corporate social responsibility project to be successful, several factors come into play: the project needs to be sustainable, its topic and practice abide by ethical standards, sensitive to society’s needs, embraced and supported by the company’s employees, create the aimed effect on the target audience, and every year, and the project needs to be evaluated to see how beneficial it is.” The Financial Impact of the Triple Bottom Line When examining the value of corporate responsibility, one must understand the concept of the triple bottom line (TBL), which essentially measures the sustainability of an organization’s social responsibility efforts. The term includes three dimensions of a giving business—profits, people, and the planet. Without one of these factors, there cannot be a balance. According to economist Andrew Savitz, the triple bottom line “captures the essence of sustainability by measuring the impact of an organization’s activities on the world ... including both its profitability and shareholder values and its social, human and environmental capital.” The challenge with the TBL model is that while profits can be measured in dollars, and people can be measured in numbers, it can be difficult to measure the impact of social responsibility. Some argue that this task is dependent upon what is being measured. For example, if one is saving the rainforest, a reasonable unit of measurement could be acreage. Progress toward protecting this resource could be recorded as how many fewer acres have been forested and how many native (people) communities have been saved as a result of the intervention. Another example could be a social cause, such as creating housing for single parents in poverty-stricken neighborhoods in a specific city. The impact can be felt in terms of the additional housing that is created (built or rehabbed from existing homes), and the value that this effort brings to the neighborhood. The number of people helped can be measured. The city’s rate of homelessness can be measured as it is reduced. Then, there are other equally important results of social responsibility that can be considered, such as the reduced rate of crime in areas with homeowners, and an increase in employment for those who own the homes. These indirect benefits have an impact on the company because it can eventually hire people from these areas of the city. Businesses must be continually mindful of the image that they project to the world and be sure to align their corporate social responsibility campaigns with their culture. An authentic cause that is backed by all is far better than one that is dreamt up purely for the sake of marketing.
principles_of_accounting,_volume_1:_financial_accounting
Summary 15.1 Describe the Advantages and Disadvantages of Organizing as a Partnership There are many advantages and disadvantages of partnership as a form of business entity and they should be carefully considered. The most significant advantage of partnerships is the exemption from tax at the business level. Partners are taxed on their share of the profit or loss at their individual tax rates. Mutual agency and unlimited liability should be weighed against the tax benefits of partnership. There are other entity forms that have many of the characteristics of standard partnerships. These other entity forms often share the legal liability protection of corporations, and the tax and personal benefits of a partnership. 15.2 Describe How a Partnership Is Created, Including the Associated Journal Entries Partners must consider several factors when developing their partnership agreement, such as the contributions and authority of each partner and a means to resolve disputes. Non-cash assets such as equipment and prepaid expenses should be recorded at current market values. Partners are sometimes given an ownership interest based on their expertise or experience instead of any contributed assets. Liabilities assumed by the partnership should be recorded at their current value. 15.3 Compute and Allocate Partners’ Share of Income and Loss There are several different approaches to sharing the income or loss of a partnership, including fixed ratios, capital account balances, and combinations of the two. 15.4 Prepare Journal Entries to Record the Admission and Withdrawal of a Partner There are two different methods for admitting a new partner to a partnership—direct investment to the partnership (affects partnership assets) and transaction among partners (does not affect partnership assets). There are two different methods for a partner to withdraw from a partnership—direct payment from the partnership and direct payment from the partners. 15.5 Discuss and Record Entries for the Dissolution of a Partnership There are times, such as following bankruptcy, death, or retirement, when a partnership ceases operation. The following four accounting steps must be taken, in order, to dissolve a partnership: sell noncash assets; allocate any gain or loss on the sale based on the income-sharing ratio in the partnership agreement; pay off liabilities; distribute any remaining cash to partners based on their capital account balances.
Chapter Outline 15.1 Describe the Advantages and Disadvantages of Organizing as a Partnership 15.2 Describe How a Partnership Is Created, Including the Associated Journal Entries 15.3 Compute and Allocate Partners’ Share of Income and Loss 15.4 Prepare Journal Entries to Record the Admission and Withdrawal of a Partner 15.5 Discuss and Record Entries for the Dissolution of a Partnership Why It Matters As a recent graduate of a landscape architecture program, Ciara is ready to start her professional career. Dale, her friend from high school, has started a small lawn mowing and hardscape business and wants to expand his services. Ciara and Dale sit down and work out that if they combine their talents, they will be able to take advantage of a growing need in their local housing market. They agree to form a partnership, and together they decide what each person will contribute to the business. Ciara has committed to invest cash, and Dale will contribute assets he has acquired in his business. In addition to the assets that each will provide, Ciara will contribute her expertise in landscape design, while Dale will contribute his experience in property maintenance and stonework/wood design and construction. They set out on their adventure, creating a partnership agreement and detailing the roles each will play in this newly created partnership. At first, business is great and they work well together. There is one problem: they have more business than they can handle, and they are getting requests for services they currently don’t provide. However, Ciara’s friend Remi is a pond installer. From speaking with Remi, she knows he is very dedicated and has a vast customer base. She realizes that if he joins the partnership, the company can handle all the business demand better. Therefore, Ciara and Dale decide to amend the partnership agreement and admit Remi as a new one-third partner.
[ { "answer": { "ans_choice": 3, "ans_text": "D" }, "bloom": null, "hl_context": "<hl> A general partnership is an association in which each partner is personally liable to the partnership ’ s creditors if the partnership has insufficient assets to pay its creditors . <hl> <hl> These partners are often referred to as general partners . <hl> A limited partnership ( LP ) is an association in which at least one partner is a general partner but the remaining partners can be limited partners , which means they are liable only for their own investment in the firm if the partnership cannot pay its creditors . Thus , their personal assets are not at risk .", "hl_sentences": "A general partnership is an association in which each partner is personally liable to the partnership ’ s creditors if the partnership has insufficient assets to pay its creditors . These partners are often referred to as general partners .", "question": { "cloze_format": "A partnership ________.", "normal_format": "Which of the following is correct about a partnership?", "question_choices": [ "has one owner", "can issue stock", "pays taxes on partnership income", "can have more than one general partner" ], "question_id": "fs-idm319285344", "question_text": "A partnership ________." }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 2, "ans_text": "become the property of all the partners" }, "bloom": null, "hl_context": "Co-ownership of property . <hl> In a partnership , assets are jointly owned by all partners . <hl> If a dissolution occurs , each partner retains a claim on the total assets proportional to that partner ’ s equity in the organization . The rule presented herein does not apply to specific assets .", "hl_sentences": "In a partnership , assets are jointly owned by all partners .", "question": { "cloze_format": "Any assets invested by a particular partner in a partnership ________.", "normal_format": "Which of the following is correct about any assets invested by a particular partner in a partnership?", "question_choices": [ "do not become a partnership asset but instead remain with the partner", "can be used only by the investing partner", "become the property of all the partners", "are the basis for all profit sharing" ], "question_id": "fs-idm365829184", "question_text": "Any assets invested by a particular partner in a partnership ________." }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 0, "ans_text": "A" }, "bloom": null, "hl_context": "<hl> Potential Disadvantages <hl> <hl> Mutual agency and partnership disagreements . <hl> Mutual agency is the right of all partners to represent the business and bind the partnership to contracts and agreements . This rule applies regardless of whether all the partners agree with the contract or agreement . Mutual agency could cause tension among the partners , since any of them can bind the partnership and make everyone liable as long as the action is taken in the interest of furthering the partnership . <hl> Unlimited liability . <hl> Unlimited liability is the legal obligation of all general partners for the partnership ’ s debts regardless of which partner incurred them . This liability can extend to the partners ’ personal assets . Limited life . <hl> The partnership ends when a new partner is accepted into the partnership , a partner leaves , a partner dies , or the partnership dissolves . <hl> <hl> Therefore , most partnerships tend to have limited lives . <hl> <hl> Taxation subject to individual ’ s tax rate . <hl> <hl> Individual partners often have other sources of income outside the partnership ; this can make their allocated partnership income taxable at a higher rate than if the partnership were liable for the income taxes instead . <hl> <hl> Relative lack of regulation . <hl> You learned , for example , that a partnership ’ s informal agreement not need be in writing . But this could lead to legal disputes between partners and expose them to unlimited liability , something individuals in corporations do not need to worry about ( they are liable only for the amount of their investment in the corporation ’ s stock ) . <hl> Difficulty of ownership transfer . <hl> Since a partnership dissolves when there is a change in ownership , it tends to be difficult to transfer ownership . It is a complicated process when a new partner is added or a partnership interest is sold , requiring asset valuation and negotiation of previously agreed upon partnership operating terms . <hl> Disadvantages of Organizing as a Partnership <hl>", "hl_sentences": "Potential Disadvantages Mutual agency and partnership disagreements . Unlimited liability . The partnership ends when a new partner is accepted into the partnership , a partner leaves , a partner dies , or the partnership dissolves . Therefore , most partnerships tend to have limited lives . Taxation subject to individual ’ s tax rate . Individual partners often have other sources of income outside the partnership ; this can make their allocated partnership income taxable at a higher rate than if the partnership were liable for the income taxes instead . Relative lack of regulation . Difficulty of ownership transfer . Disadvantages of Organizing as a Partnership", "question": { "cloze_format": "___ is a disadvantage of the partnership form of organization.", "normal_format": "Which of the following is a disadvantage of the partnership form of organization?", "question_choices": [ "limited life", "no taxation at the partnership level", "flexibility in business operations", "combining of financial resources" ], "question_id": "fs-idm364658336", "question_text": "Which of the following is a disadvantage of the partnership form of organization?" }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 1, "ans_text": "the right of all partners to represent the company’s normal business operations" }, "bloom": null, "hl_context": "Mutual agency and partnership disagreements . <hl> Mutual agency is the right of all partners to represent the business and bind the partnership to contracts and agreements . <hl> This rule applies regardless of whether all the partners agree with the contract or agreement . Mutual agency could cause tension among the partners , since any of them can bind the partnership and make everyone liable as long as the action is taken in the interest of furthering the partnership . Mutual agency . <hl> In a partnership , partners are considered agents of the entity . <hl> <hl> Mutual agency give each partner the ability to act as an agent for the partnership in dealing with outside entities such as vendors and lenders . <hl> The partnership is then bound by the actions of each partner acting within the scope of partnership activities .", "hl_sentences": "Mutual agency is the right of all partners to represent the business and bind the partnership to contracts and agreements . In a partnership , partners are considered agents of the entity . Mutual agency give each partner the ability to act as an agent for the partnership in dealing with outside entities such as vendors and lenders .", "question": { "cloze_format": "Mutual agency is defined as ___.", "normal_format": "How is mutual agency defined?", "question_choices": [ "a mutual agreement", "the right of all partners to represent the company’s normal business operations", "a synonym for partnership", "a partnership between two partnerships" ], "question_id": "fs-idm366152752", "question_text": "Mutual agency is defined as:" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 2, "ans_text": "C" }, "bloom": null, "hl_context": "<hl> process for settling disputes <hl> <hl> process for partnership dissolutions <hl> <hl> process for change in partners <hl> <hl> partners ’ authority and decision-making role <hl> <hl> allocation of profit , losses , and draws ( withdrawals ) among the partners <hl> <hl> capital contributions of each partner <hl> <hl> Ideally , the agreement to form a partnership should be in the form of a written contract . <hl> <hl> This partnership agreement details the partners ’ roles , the way profits and losses are shared , and the contributions each partner makes to the partnership . <hl> It also should contain basic information such as the business ’ s name , its location , its purpose or mission , the names of the partners , and the date of inception . Even more importantly , it should outline the following information . There is no legal requirement for a written partnership agreement . In fact , individuals can end up in court after forming a partnership agreement by accident with no written documentation . It is strongly suggested that any business relationship has a written agreement . <hl> A properly drafted agreement will often contain the following details : <hl>", "hl_sentences": "process for settling disputes process for partnership dissolutions process for change in partners partners ’ authority and decision-making role allocation of profit , losses , and draws ( withdrawals ) among the partners capital contributions of each partner Ideally , the agreement to form a partnership should be in the form of a written contract . This partnership agreement details the partners ’ roles , the way profits and losses are shared , and the contributions each partner makes to the partnership . A properly drafted agreement will often contain the following details :", "question": { "cloze_format": "___ would not be considered in the development of a partnership agreement.", "normal_format": "Which one of the following would not be considered in the development of a partnership agreement?", "question_choices": [ "profit and loss levels", "processing disputes", "stock options", "asset contributions" ], "question_id": "fs-idm367123120", "question_text": "Which one of the following would not be considered in the development of a partnership agreement?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 3, "ans_text": "Partner’s individual tax rate" }, "bloom": null, "hl_context": "<hl> process for settling disputes <hl> <hl> process for partnership dissolutions <hl> <hl> process for change in partners <hl> <hl> partners ’ authority and decision-making role <hl> <hl> allocation of profit , losses , and draws ( withdrawals ) among the partners <hl> <hl> capital contributions of each partner <hl> Ideally , the agreement to form a partnership should be in the form of a written contract . This partnership agreement details the partners ’ roles , the way profits and losses are shared , and the contributions each partner makes to the partnership . It also should contain basic information such as the business ’ s name , its location , its purpose or mission , the names of the partners , and the date of inception . Even more importantly , it should outline the following information . There is no legal requirement for a written partnership agreement . In fact , individuals can end up in court after forming a partnership agreement by accident with no written documentation . It is strongly suggested that any business relationship has a written agreement . <hl> A properly drafted agreement will often contain the following details : <hl>", "hl_sentences": "process for settling disputes process for partnership dissolutions process for change in partners partners ’ authority and decision-making role allocation of profit , losses , and draws ( withdrawals ) among the partners capital contributions of each partner A properly drafted agreement will often contain the following details :", "question": { "cloze_format": "A well written partnership agreement should include each of the following except ________.", "normal_format": "A well written partnership agreement should not include which of the following?", "question_choices": [ "how to settle disputes", "the name of the partnership", "division of responsibilities", "Partner’s individual tax rate" ], "question_id": "fs-idm390562608", "question_text": "A well written partnership agreement should include each of the following except ________." }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 1, "ans_text": "starts over, using the contributed value as the new cost basis" }, "bloom": null, "hl_context": "<hl> When used fixed assets are contributed , depreciation is calculated based on their fair value and the partnership ’ s estimate of their useful life . <hl> <hl> Fixed assets are contributed at their fair value , not the book value on the partner ’ s individual books before the formation of the partnership . <hl> ( In our examples , assume all the partners were sole proprietors before the formation of the partnership . )", "hl_sentences": "When used fixed assets are contributed , depreciation is calculated based on their fair value and the partnership ’ s estimate of their useful life . Fixed assets are contributed at their fair value , not the book value on the partner ’ s individual books before the formation of the partnership .", "question": { "cloze_format": "A newly formed partnership handles the contribution of previously depreciated assets by ___ .", "normal_format": "How does a newly formed partnership handle the contribution of previously depreciated assets?", "question_choices": [ "continues the depreciation life as if the owner had not changed", "starts over, using the contributed value as the new cost basis", "shortens the useful life of the asset per the partnership agreement", "does not depreciate the contributed asset" ], "question_id": "fs-idm408349888", "question_text": "How does a newly formed partnership handle the contribution of previously depreciated assets?" }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 2, "ans_text": "C" }, "bloom": null, "hl_context": "<hl> Step 4 : Distribute any remaining cash to the partners on the basis of their capital balances . <hl> <hl> Step 3 : Pay partnership liabilities in cash . <hl> <hl> Step 2 : Allocate the gain or loss from realization to the partners based on their income ratios . <hl> <hl> Step 1 : Sell noncash assets for cash and recognize a gain or loss on realization . <hl> <hl> Realization is the sale of noncash assets for cash . <hl> <hl> As discussed above , the liquidation or dissolution of a partnership is synonymous with closing the business . <hl> This may occur due to mutual partner agreement to sell the business , the death of a partner , or bankruptcy . Before proceeding with liquidation , the partnership should complete the accounting cycle for its final operational period . This will require closing the books with only balance sheet accounts remaining . <hl> Once that process has been completed , four steps remain in the accounting for the liquidation , each requiring an accounting entry . <hl> <hl> They are : <hl>", "hl_sentences": "Step 4 : Distribute any remaining cash to the partners on the basis of their capital balances . Step 3 : Pay partnership liabilities in cash . Step 2 : Allocate the gain or loss from realization to the partners based on their income ratios . Step 1 : Sell noncash assets for cash and recognize a gain or loss on realization . Realization is the sale of noncash assets for cash . As discussed above , the liquidation or dissolution of a partnership is synonymous with closing the business . Once that process has been completed , four steps remain in the accounting for the liquidation , each requiring an accounting entry . They are :", "question": { "cloze_format": "When a partnership dissolves, the first step in the dissolution process is to ________.", "normal_format": "When a partnership dissolves, what is the first step in the dissolution process?", "question_choices": [ "allocate the gain or loss on sale based on income sharing ratio", "pay off liabilities", "sell noncash assets", "divide the remaining cash among the partners" ], "question_id": "fs-idm278353056", "question_text": "When a partnership dissolves, the first step in the dissolution process is to ________." }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 3, "ans_text": "divide the remaining cash among the partners" }, "bloom": null, "hl_context": "<hl> Step 4 : Distribute any remaining cash to the partners on the basis of their capital balances . <hl> <hl> Step 3 : Pay partnership liabilities in cash . <hl> <hl> Step 2 : Allocate the gain or loss from realization to the partners based on their income ratios . <hl> <hl> Step 1 : Sell noncash assets for cash and recognize a gain or loss on realization . <hl> <hl> Realization is the sale of noncash assets for cash . <hl> <hl> The liquidation or dissolution process for partnerships is similar to the liquidation process for corporations . <hl> Over a period of time , the partnership ’ s non-cash assets are converted to cash , creditors are paid to the extent possible , and remaining funds , if any , are distributed to the partners . <hl> Partnership liquidations differ from corporate liquidations in some respects , however : <hl>", "hl_sentences": "Step 4 : Distribute any remaining cash to the partners on the basis of their capital balances . Step 3 : Pay partnership liabilities in cash . Step 2 : Allocate the gain or loss from realization to the partners based on their income ratios . Step 1 : Sell noncash assets for cash and recognize a gain or loss on realization . Realization is the sale of noncash assets for cash . The liquidation or dissolution process for partnerships is similar to the liquidation process for corporations . Partnership liquidations differ from corporate liquidations in some respects , however :", "question": { "cloze_format": "When a partnership dissolves, the last step in the dissolution process is to ________.", "normal_format": "When a partnership dissolves, what is the last step in the dissolution process?", "question_choices": [ "allocate the gain or loss on sale based on income sharing ratio", "pay off liabilities", "sell noncash assets", "divide the remaining cash among the partners" ], "question_id": "fs-idm274075888", "question_text": "When a partnership dissolves, the last step in the dissolution process is to ________." }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 1, "ans_text": "B" }, "bloom": null, "hl_context": "As discussed above , the liquidation or dissolution of a partnership is synonymous with closing the business . This may occur due to mutual partner agreement to sell the business , the death of a partner , or bankruptcy . <hl> Before proceeding with liquidation , the partnership should complete the accounting cycle for its final operational period . <hl> This will require closing the books with only balance sheet accounts remaining . Once that process has been completed , four steps remain in the accounting for the liquidation , each requiring an accounting entry . They are :", "hl_sentences": "Before proceeding with liquidation , the partnership should complete the accounting cycle for its final operational period .", "question": { "cloze_format": "Prior to proceeding with the liquidation, the partnership should ________.", "normal_format": "Prior to proceeding with the liquidation, what should the partnership do?", "question_choices": [ "prepare adjusting entries without closing", "complete the accounting cycle for final operational period", "prepare only closing entries", "complete financial statements only" ], "question_id": "fs-idm273838272", "question_text": "Prior to proceeding with the liquidation, the partnership should ________." }, "references_are_paraphrase": null } ]
15
15.1 Describe the Advantages and Disadvantages of Organizing as a Partnership A partnership is legal business structure consisting of an association of two or more people who contribute money, property, or services to operate as co-owners of a business. When discussing partnerships as a form of business ownership, the term person can refer to individuals, corporations, or even other partnerships. However, in this chapter, all the partners are individuals. Think It Through Choosing a Partner In some ways, a partnership is like a marriage; choosing a partner requires a great deal of thought. How do you know whether you and your potential partner or partners will be a good fit? A strong partnership agreement is one way to help settle future disagreements. But before you get that far, it is really important to take a hard look at future partners. How do they deal with stressful situations? What skills and assets do they possess that you do not, and vice versa? What work ethic do they exemplify? Do they procrastinate? Are they planners? Do they get along with others? Do the two of you work well with each other? All these questions and many more should be explored before choosing business partners. While you cannot predict the future or see all possible issues, doing your due diligence will help. What other questions can you think of that would help you decide whether someone will be a good business partner for you? Characteristics of a Partnership Just like a corporation, a partnership is a legal entity. It can own property and can be held legally liable for its actions. It is a separate entity from its owners, the partners . Partnerships have several distinct characteristics that set them apart from other entity types. The most common characteristics of a partnership are the following: Formation by agreement. A partnership is formed by voluntary membership or association. The partners must have an agreement about who contributes assets or services, who performs what functions of the business, and how profits and losses and any additional compensation are shared. Ideally, this agreement should be in writing; however, if not, the Uniform Partnership Act or the Revised Uniform Partnership Act (RUPA) governs in areas of disagreement, depending on the state in which the partnership is located. Defined or limited life. Typically, the life term of the partnership is established by agreement. Unlike corporations, which have an unlimited life, partnerships end when a new partner is accepted or a partner leaves (and a new partnership may be created), or the partnership dissolves. Mutual agency. In a partnership, partners are considered agents of the entity. Mutual agency give each partner the ability to act as an agent for the partnership in dealing with outside entities such as vendors and lenders. The partnership is then bound by the actions of each partner acting within the scope of partnership activities. Unlimited liability. Due to mutual agency, any partner has the ability to incur debt for the partnership. Regardless of who negotiated the debt, each partner is liable to pay it if the debt was incurred to further partnership activities. There are exceptions to this, but only for partners who meet limited partnership standards (which you will learn about later in this chapter). If you are considered a general partner , you are liable for the business’s debt. Non-taxable income at partnership level. The net income of a partnership is not subject to federal taxation at the partnership level, despite the company’s being a separate legal entity from its partners. Instead, its income or loss is allocated among the partners based upon the partnership agreement and tax legislation, and the allocation is reported on each partner’s Tax Form K-1. The tax information on each partner’s K-1 is then incorporated into each partner’s individual tax return, and tax is paid at each individual partner’s relevant tax rate. Income tax is levied on the partners regardless of how much of that taxable income is actually withdrawn by the partner in a given year. For example, assume that a partner earned $20,000 in taxable income from a partnership in 2019 and withdrew $25,000 as a draw. The partner’s taxable income from the partnership for the year is $20,000. Draws are not considered taxable income. Instead, they are withdrawals from a partner’s capital account. However, the $25,000 draw in this example reduces the partner’s capital account by $25,000. Co-ownership of property. In a partnership, assets are jointly owned by all partners. If a dissolution occurs, each partner retains a claim on the total assets proportional to that partner’s equity in the organization. The rule presented herein does not apply to specific assets. Limited capital investment. Unlike a corporation, which is able to raise capital investments by issuing stock, partners do not have the ability to raise capital except by incurring additional debt or agreeing to contribute more of their personal assets. This limits the partnerships’ ability for rapid expansion. Participation in both income and loss. The net income or loss of the partnership is distributed as specified in the partnership agreement. If the arrangement is not specified in the partnership agreement, all partners participate equally in net income or losses. IFRS Connection Partnerships and IFRS You’ve learned how partnerships are formed, and you will soon learn how partnership capital and income can be allocated and what happens to the capital structure when a partner is added or subtracted. But how does a partnership account for normal day-to-day business transactions? Partnership organizations can be very small, very large, or any size in between. What type of accounting rules do partnerships use to record their daily business activities? Partnerships can choose among various forms of accounting. The options broadly include using a cash basis, a tax basis, and a full accrual basis to track transactions. When choosing to use the full accrual basis of accounting, partnerships apply U.S. GAAP rules in their accounting processes. But you may be surprised to learn that some non-publicly traded partnerships in the United States can use IFRS, or a simpler form of IFRS known as IFRS for Small and Medium Sized Entities (SMEs). In 2008, the AICPA designated IFRS and IFRS for SMEs as acceptable sets of generally accepted accounting principles. However, it is up to each State Board of Accountancy to determine whether that state will allow the use of IFRS or IFRS for SMEs by non-public entities incorporated in that state. Despite the use of size descriptors in the title, qualifying as a small- or medium-sized entity has nothing to do with size. A SME is any entity that publishes general purpose financial statements for public use but does not have public accountability. In other words, the entity is not publicly traded. In addition, the entity, even if it is a partnership, cannot act as a fiduciary; for example, it cannot be a bank or insurance company and use SME rules. Why might a partnership want to use IFRS for SMEs? First, IFRS for SMEs contains fewer and simpler standards. IFRS for SMEs is only about 300 pages in length, whereas regular IFRS is over 2,500 pages long and U.S. GAAP is over 25,000 pages. Second, IFRS for SMEs is modified only every three years, whereas U.S. GAAP and IFRS are modified more frequently. This means entities using IFRS for SMEs don’t have to adjust their accounting systems and reporting to new standards as frequently. Finally, if a partnership transacts business with international businesses or hopes to attract international partners, seek capital from international sources, or be bought out by an international company, having its financial statements in IFRS form can make these transactions easier. Advantages of Organizing as a Partnership When it comes to choosing a legal structure or form for your business, the most common options are sole proprietorships, partnerships, and different forms of corporations, each with advantages and disadvantages. Partnerships have several advantages over other forms of business entities, as follows: Exemption from taxation at the partnership level. A significant advantage to forming a partnership is the exemption from taxation as a business entity. In other words, although the individual partners are taxed at the individual level, the partnership itself (as a business unit) is not subject to income tax. The tax characteristics of a partnership “flow through” to the individual partners. Ease and lower cost of formation. Most business regulations tend to be written for corporations, which is to be expected given the complexities of many such companies. Partnerships, on the other hand, are simpler and have to comply with fewer regulations. Also, without shareholders, partnerships have fewer reporting requirements. The partnership formation paperwork also tends to be less cumbersome than that for other entities in most states. Overall, partnerships are simple to form, alter, and terminate. Combined skills and financial resources. Combining business acumen and financial assets can give a partnership an advantage over sole proprietorships. Flexibility in managing and running the business. Partnerships are often simpler to manage and run than other business structures (except for most sole proprietorships), and they can offer more management flexibility as well if the partners generally agree on management issues. Since there is no board of directors overseeing operations, partnerships can be nimble and make speedy changes—again, as long as the partners agree. Easily changed business structure. It is a relatively easy process to convert a partnership to a corporation in the future. With no shareholders to consider, a partnership’s capital can be converted to shares of common stock. Informality. Unlike publicly traded corporations, partnerships do not need to prepare articles of incorporation, write bylaws, issue stock certificates to owners, document minutes or board meetings, pay incorporation fees to states, or file quarterly financial statements with the SEC. However, it is advised that partners create a written document detailing decision on issues such as profit sharing, dispute resolution procedures, partnership changes, and other terms that the partners might agree upon to prevent future complications. Your Turn All in the Family Family partnerships are frequently utilized to allow family members to pool resources for investment purposes and to transfer assets in a tax-efficient manner. In what ways can you imagine using a family partnership? Solution Cash can be combined to purchase income-producing properties or other investments without having to sell assets, thus keeping costly investments all in the family. Through a family partnership, it becomes possible for those in high net worth tax brackets to transfer assets and wealth to younger generations in a way that reduces potential estate and gift taxes. For example, a family partnership can be formed by a grandparent who owns an apartment building. Children and grandchildren can be partners to share in profits of the building. As they earn the income from the building while living, this can be a very tax efficient way to transfer wealth. Disadvantages of Organizing as a Partnership While partnerships carry some clear advantages, there are also several disadvantages to consider. For example, due to unlimited liability, each partner in a general partnership is equally and personally liable for all the debts of the partnership. Following are some of the disadvantages of the partnership form of business organization: Difficulty of ownership transfer. Since a partnership dissolves when there is a change in ownership, it tends to be difficult to transfer ownership. It is a complicated process when a new partner is added or a partnership interest is sold, requiring asset valuation and negotiation of previously agreed upon partnership operating terms. Relative lack of regulation. You learned, for example, that a partnership’s informal agreement not need be in writing. But this could lead to legal disputes between partners and expose them to unlimited liability, something individuals in corporations do not need to worry about (they are liable only for the amount of their investment in the corporation’s stock). Taxation subject to individual’s tax rate. Individual partners often have other sources of income outside the partnership; this can make their allocated partnership income taxable at a higher rate than if the partnership were liable for the income taxes instead. Limited life. The partnership ends when a new partner is accepted into the partnership, a partner leaves, a partner dies, or the partnership dissolves. Therefore, most partnerships tend to have limited lives. Unlimited liability. Unlimited liability is the legal obligation of all general partners for the partnership’s debts regardless of which partner incurred them. This liability can extend to the partners’ personal assets. Mutual agency and partnership disagreements. Mutual agency is the right of all partners to represent the business and bind the partnership to contracts and agreements. This rule applies regardless of whether all the partners agree with the contract or agreement. Mutual agency could cause tension among the partners, since any of them can bind the partnership and make everyone liable as long as the action is taken in the interest of furthering the partnership. Limited ability to raise capital. A partnership is often limited in its ability to raise capital or additional funds, whether from the individual partners themselves or from a financial institution making a loan. Concepts In Practice Sports Memorabilia Store Farah and David decide to form a sports memorabilia retail partnership. They have known each other since business graduate school and have always worked well together on various projects. The business is doing well but cash flow is very tight. Farah takes several calls from vendors asking for payment. He believed David had been paying the bills. When he asks about this, David admits to embezzling from the partnership. What liability does Farah face as a result of the theft? Table 15.1 summarizes some of the main advantages and disadvantages of the partnership form of business organization. Advantages and Disadvantages of Forming a Partnership Potential Advantages Potential Disadvantages No taxation at the partnership level Ease and lower cost of formation Combined skills and financial resources Flexibility in managing and running the business Easily changed business structure Informality Difficulty of ownership transfer Relative lack of oversight/regulation Number of partners needed Taxation subject to individual’s tax rate Limited life Unlimited liability Mutual agency and potential for partnership disagreements Limited ability to raise capital Table 15.1 Types of Partnerships A general partnership is an association in which each partner is personally liable to the partnership’s creditors if the partnership has insufficient assets to pay its creditors. These partners are often referred to as general partners. A limited partnership (LP) is an association in which at least one partner is a general partner but the remaining partners can be limited partners, which means they are liable only for their own investment in the firm if the partnership cannot pay its creditors. Thus, their personal assets are not at risk. Finally, the third type is a limited liability partnership (LLP) , which provides all partners with limited personal liability against another partner’s obligations. Limited liability is a form of legal liability in which a partner’s obligation to creditors is limited to his or her capital contributions to the firm. These types of partnerships include “LLP” or partnership in their names and are usually formed by professional groups such as lawyers and accountants. Each partner is at risk however, for his or her own negligence and wrongdoing as well as the negligence and wrongdoing of those who are under the partners’ control or direction. Table 15.2 summarizes the advantages and disadvantages of different types of partnerships. Advantages and Disadvantages of Types of Partnerships Type of partnership Advantages Disadvantages General partnership Business is simple to form All partners have personal liability Limited partnership (LP) Limited partners have limited liability General partners are personally liable Limited liability partnership (LLP) Partners are protected from other partners’ malpractice Some partners remain personally liable Table 15.2 Link to Learning Arthur Andersen was one of the “Big 5” accounting firms until it was implicated in the Enron scandal. Arthur Andersen had been formed as an LLP. Read this CNN Money article about the Arthur Andersen case to see how courts can hold partners liable. Dissolution of a Partnership Dissolution occurs when a partner withdraws (due to illness or any other reason), a partner dies, a new partner is admitted, or the business declares bankruptcy. Whenever there is a change in partners for any reason, the partnership must be dissolved and a new agreement must be reached. This does not preclude the partnership from continuing business operations; it only changes the document underlying the business. In some cases, the new partnership may also require the revaluation of partnerships assets and, possibly, their sale. Ideally, the partnership agreement has been written to address dissolution. 15.2 Describe How a Partnership Is Created, Including the Associated Journal Entries After examining all the relevant factors, Dale and Ciara decide to create their landscaping partnership. After much discussion, they agree on the name Acorn Lawn & Hardscapes. The first step is to formally document the actual partnership agreement. While a handshake would work, it is far more sensible to document it in case of disagreement. Creation of a Partnership Ideally, the agreement to form a partnership should be in the form of a written contract. This partnership agreement details the partners’ roles, the way profits and losses are shared, and the contributions each partner makes to the partnership. It also should contain basic information such as the business’s name, its location, its purpose or mission, the names of the partners, and the date of inception. Even more importantly, it should outline the following information. There is no legal requirement for a written partnership agreement. In fact, individuals can end up in court after forming a partnership agreement by accident with no written documentation. It is strongly suggested that any business relationship has a written agreement. A properly drafted agreement will often contain the following details: capital contributions of each partner allocation of profit, losses, and draws (withdrawals) among the partners partners’ authority and decision-making role process for change in partners process for partnership dissolutions process for settling disputes The partners should also consider the following items: Name of the partnership. The business needs a name. Many partnerships are named for the partners or the location, or the partners can choose and register an invented name. In many situations, if you are using an invented name you must file a Doing Business As (DBA) statement with the appropriate governmental agency. Contributions to the partnership. Important to the start of any business is finding the capital and equipment with which to begin. The partners should agree up front about what each partner will contribute, how the contribution will be recorded, and how the investment will affect each partner’s share of ownership. For example, it is common for a partnership to allocate an ownership interest to a partner who has valuable experience or contacts in an area of interest to a partnership. Partners can also contribute service to the partnership rather than assets. Failure to address these details can derail a business before it even starts. Partners’ authority. As you’ve learned, mutual agency can allow every partner to bind the partnership in agreements with outside vendors or lenders. If the authority of each partner has not been documented, problems can arise. Thus, it is important to outline who is responsible for what. The same goes for decision making. A strong agreement will outline how decision are made and at what thresholds all the partners need to be involved. A final point to cover is how management responsibilities will be divided up. Allocation of profits, losses, and draws. How will the partners share in the profits or losses of the partnership? Will any of the partners receive a guaranteed payment (salary)? If so, how much? Each partner is going to have different needs and requirements, and these should be agreed upon to avoid dispute. Change in Partners. At some point there may be a change in partners – whether it is an addition or a withdrawal. A well-drafted partnership agreement will create rules for how that can happen. Dispute resolution. Selecting a means to resolve conflicts may one may be the most important choices for the new partners to make. It is human nature to disagree; the partnership agreement should cover how disputes will be handled so they do not interrupt business in the future. Once the partnership agreement is complete, there are other steps to take to create the business as a legal entity. Select the state in which you plan to operate. Typically, partnerships choose the state in which they are located. Since the partnership does not pay taxes and regulations are limited, state selection is not as important as it is for a corporation. Register the name with the authorities required by the state in which the partnership is formed. This allows the partnership to use the name and prevents others from selecting it. Obtain the required business licenses. If your partnership will be selling items subject to sales tax, you will need to obtain a sales tax license. If you are operating as a professional services firm, there may be state licensing requirements – attorneys, physicians, and certified public accountants (CPAs) are especially subject to license requirements. Ethical Considerations Ethical Obligations to Partners Recall that each partner is jointly and severally liable for all the debts of the partnership, meaning each partner is personally liable for these obligations. As a result, in most business settings and jurisdictions, the actions of any partner are attributed to the partnership and each of its partners, whether the actions were approved by all partners or not. For example, if partner A signs a loan agreement on behalf of the partnership and the partnership defaults on the loan, partner B can be personally liable for the loan, even though this partner had no role in signing the initial agreement. Due to this unlimited liability, whether there is a written partnership agreement or not, partners have an ethical duty to act in the best interests of the partnership and of each of their partners. This is generally called a fiduciary duty . A fiduciary is someone who has a legal and/or ethical obligation to act in the best interest of others in order to maintain a relationship of trust and confidence. What this means in practice is that partners are to avoid actual and potential conflicts of interests, and there is to be no self-dealing. Partners are expected to put the partnership’s interest ahead of their own. Formation of the Partnership Each partner’s initial contribution is recorded on the partnership’s books. These contributions are recorded at the fair value of the asset at the date of transfer. All partners must agree to the valuation being recorded. As an example, let’s go back to Dale and Ciara. On January 1, 2019 they combined their resources into a general partnership named Acorn Lawn & Hardscapes. They agree to a 50:50 split of income and losses. As stated earlier, Ciara will invest cash and Dale has real assets to contribute to the partnership. Dale’s contributed assets include lawn equipment that he bought or created based on his specific needs. The equipment had a book value (determined in the process of filing Dale’s past individual income taxes) of $5,600 and a fair market value (the current price at which it would sell) of $6,400. He also contributed accounts receivable from his business with a book value of $2,000. However, he expects to collect only $1,600 of it, so he is contributing accounts receivable with a market value of $1,600. Since Ciara contributed cash of $8,000 and no other assets, her contribution has a book value and a fair market value of $8,000 ( Figure 15.2 ). Note this point about the formation of a partnership when its assets’ fair market value differs from their book value: it wouldn’t make sense to base the value of the capital contribution of assets (or liabilities) on their book value. To see why, consider the equipment and accounts receivable contributions made by Dale. The equipment had a book value of $5,600 and a fair value of $6,400. Why should Dale get credit for a contribution of only the $5,600 book value when he could have sold the equipment for $6,400 and contributed $6,400 in cash, instead of the equipment with a fair value of $6,400? The same principle applies to Dale’s Accounts Receivable but in the opposite direction. Dale is contributing Accounts Receivable with a book value of $2,000, but since the partnership expects to collect only $1,600, that is the amount of capital contribution credit he will receive. The journal entries would be as follows: When used fixed assets are contributed, depreciation is calculated based on their fair value and the partnership’s estimate of their useful life. Fixed assets are contributed at their fair value, not the book value on the partner’s individual books before the formation of the partnership. (In our examples, assume all the partners were sole proprietors before the formation of the partnership.) Likewise, if the partnership were to assume liabilities from one of the partners, the liability would be recorded at the current value. And, as demonstrated above, any non-cash assets contributed to the partnership should be valued at their current values. 15.3 Compute and Allocate Partners’ Share of Income and Loss The landscaping partnership is going well and has realized increases in the number of jobs performed as well as in the partnership’s earnings. At the end of the year, the partners meet to review the income and expenses. Once that has been done, they need to allocate the profit or loss based upon their agreement. Allocation of Income and Loss Just like sole proprietorships, partnerships make four entries to close the books at the end of the year. The entries for a partnership are: Debit each revenue account and credit the income section account for total revenue. Credit each expense account and debit the income section account for total expenses. If the partnership had income, debit the income section for its balance and credit each partner’s capital account based on his or her share of the income. If the partnership realized a loss, credit the income section and debit each partner’s capital account based on his or her share of the loss. Credit each partner’s drawing account and debit each partner’s capital account for the balance in that same partner’s drawing account. The first two entries are the same as for a proprietorship. Both revenue and expense accounts are temporary accounts. The last two entries are different because there is more than one equity account and more than one drawing account. Capital accounts are equity accounts for each partner that track all activities, such as profit sharing, reductions due to distributions, and contributions by partners to the partnership. Capital accounts are permanent while drawing accounts must be zeroed out for each accounting period. By December 31 at the end of the first year, the partnership realized net income of $50,000. Since Dale and Ciara had agreed to a 50:50 split in their partnership agreement, each partner will record an increase to their capital accounts of $25,000. The journal records the entries to allocate year end net income to the partner capital accounts. Income Allocations Not every partnership allocates profit and losses on an even basis. As you’ve learned, the partnership agreement should delineate how the partners will share net income and net losses. The partnership needs to find a methodology that is fair and will equitably reflect each partner’s service and financial commitment to the partnership. The following are examples of typical ways to allocate income: A fixed ratio where income is allocated in the same way every period. The ratio can be expressed as a percentage (80% and 20%), a proportion (7:3) or a fraction (1/4, 3/4). A ratio based on beginning-of-year capital balances, end-of-year capital balances, or an average capital balance during the year. Partners may receive a guaranteed salary, and the remaining profit or loss is allocated on a fixed ratio. Income can be allocated based on the proportion of interest in the capital account. If one partner has a capital account that equates to 75% of capital, that partner would take 75% of the income. Some combination of all or some of the above methods. A fixed ratio is the easiest approach because it is the most straightforward. As an example, assume that Jeffers and Singh are partners. Each contributed the same amount of capital. However, Jeffers works full time for the partnership and Singh works part time. As a result, the partners agree to a fixed ratio of 0.75:0.25 to share the net income. Selecting a ratio based on capital balances may be the most logical basis when the capital investment is the most important factor to a partnership. These types of ratios are also appropriate when the partners hire managers to run the partnership in their place and do not take an active role in daily operations. The last three approaches on the list recognize differences among partners based upon factors such as time spent on the business or funds invested in it. Salaries and interest paid to partners are considered expenses of the partnership and therefore deducted prior to income distribution. Partners are not considered employees or creditors of the partnership, but these transactions affect their capital accounts and the net income of the partnership. Let’s return to the partnership with Dale and Ciara to see how income and salaries can affect the split of net income ( Figure 15.3 ). Acorn Lawn & Hardscapes reports net income of $68,000. The partnership agreement has defined an income sharing ratio, which provides for salaries of $15,000 to Dale and $10,000 to Ciara. They will share in the net income on a 50:50 basis. The calculation for income sharing between the partners is as follows: Now, consider the same scenario for Acorn Lawn & Hardscapes, but instead of net income, they realize a net loss of $32,000. The salaries for Dale and Ciara remain the same. Also, the distribution process for allocating a loss is the same as the allocation process for distributing a gain, as demonstrated above. The partners will share in the net loss on a 50:50 basis. The calculation for the sharing of the loss between the partners is shown in Figure 15.4 Concepts In Practice Spidell and Diaz: A Partnership For several years, Theo Spidell has operated a consulting company as a sole proprietor. On January 1, 2017 he formed a partnership with Juanita Diaz called Insect Management. The facts are as follows: Spidell was to transfer the cash, accounts receivable, furniture and equipment, and all the liabilities of the sole proprietorship in return for 60% of the partnership capital. The fair market value in the relevant accounts of the sole proprietorship at the close of business on December 31, 2016 are shown in Figure 15.5 . In exchange for 40% of the partnership, Diaz will invest $130,667 in cash. Each partner will be paid a salary – Spidell $3,000 per month and Diaz $2,000 per month. The partnership’s net income for 2016 was $300,000. The partnership agreement dictates an income-sharing ratio. Assume that all allocations are 60% Spidell and 40% Diaz. Record the following transactions as journal entries in the partnership’s records. Receipt of assets and liabilities from Spidell Investment of cash by Diaz Profit or loss allocation including salary allowances and the closing balance in the Income Section account Think It Through Sharing Profits and Losses in a Partnership Michael Wingra has operated a very successful hair salon for the past 7 years. It is almost too successful because Michael does not have any free time. One of his best customers, Jesse Tyree, would like to get involved, and they have had several conversations about forming a partnership. They have asked you to provide some guidance about how to share in the profits and losses. Michael plans to contribute the assets from his salon, which have been appraised at $500,000. Jesse will invest cash of $300,000. Michael will work full time at the salon and Jesse will work part time. Assume the salon will earn a profit of $120,000. Instructions: What division of profits would you recommend to Michael and Jesse? Using your recommendation, prepare a schedule sharing the net income. 15.4 Prepare Journal Entries to Record the Admission and Withdrawal of a Partner So far we have demonstrated how to create a partnership, distribute the income or loss, and calculate income distributed at the end of the year after salaries have been paid. Acorn Lawn & Hardscapes has been doing well, but what if the opportunity arises to add another partner to handle more business? Or what happens if one partner wants to leave the partnership or sell his or her interest to someone else? This section will discuss those situations. Admission of New Partner There are two ways for a new partner to join a partnership. In both, a new partnership agreement should be drawn up because the existing partnership will come to an end. The new partner can invest cash or other assets into an existing partnership while the current partners remain in the partnership. The new partner can purchase all or part of the interest of a current partner, making payment directly to the partner and not to the partnership. If the new partner buys an existing partner’s entire interest, the existing partner leaves the partnership. The new partner’s investment, share of ownership capital, and share of the net income or loss are all negotiated in the process of developing the new partnership agreement. Based on how a partner is admitted, oftentimes the admission can create a situation to be illustrated called a bonus to those in the partnership. A bonus is the difference between the value of a partner’s capital account and the cash payment made at the time of that partner’s or another partner’s withdrawal. Admission of New Partner—No Bonus Whenever a new partner is admitted to the partnership, a new capital account must be opened for him or her. This will allow the partnership to reflect the new members of the partnership. The purchase of an existing partner’s ownership by a new partner is a personal transaction that involves the existing partner and the new partner without otherwise affecting the records of the partnership. Accounting for this method is very straightforward. The only changes that are recorded on the partnership’s books occur in the two partners’ capital accounts. The existing partner’s capital account is debited and, after being created, the new partner’s capital account is credited. To illustrate, Dale decides to sell his interest in Acorn Lawn & Hardscapes to Remi. Since this is a personal transaction, the only entry Acorn needs to make is to record the transfer of partner interest from Dale to Remi on its books. No other entry needs to be made. Note that the entry is a paper transfer—it is to move the balance in the capital account. The amount paid by Remi to Dale does not affect this entry. If instead the new partner invests directly into the partnership, the change increases the assets of the partnership as well as the capital accounts. Suppose that, instead of buying Dale’s interest, Remi will join Dale and Ciara in the partnership. The following journal entry will be made to record the admission of Remi as a partner in Acorn Lawn & Hardscapes. Admission of New Partner—Bonus to Old Partners A bonus to the old partners can come about when the new partner’s investment in the partnership creates an inequity in the capital of the new partnership, such as when a new partner’s capital account is not proportionate to that of a previous partner. Because a change in ownership of a partnership produces a new partnership agreement, a bonus may be used to record the change in the ownership capital to prevent inequities among the partners. A bonus to the old partner or partners increases (or credits) their capital balances. The amount of the increase depends on the income ratio before the new partner’s admission. As an illustration, Remi is a skilled machine operator who will aid Acorn Lawn & Hardscapes in the building of larger projects. Assume the following information ( Figure 15.6 ) for the partnership on the day Remi becomes a partner. To allocate the $10,000 bonus to the old partners, Dale and Ciara, make the following calculations: Dale: ( $ 10,000 × 50 % ) = $ 5,000 Ciara: ( $ 10,000 × 50 % ) = $ 5,000 Dale: ( $ 10,000 × 50 % ) = $ 5,000 Ciara: ( $ 10,000 × 50 % ) = $ 5,000 The journal entry to record Remi’s admission to the partnership and the allocation of the bonus to Dale and Ciara is as shown. Admission of New Partner—Bonus to New Partner When the new partner’s investment may be less than his or her capital credit, a bonus to the new partner may be considered. Sometimes the partnership is more interested in the skills the new partner possesses than in any assets brought to the business. For instance, the new partner may have expertise in a particular field that would be beneficial to the partnership, or the new partner may be famous and can draw attention to the partnership as a result. This frequently happens with restaurants; many are named after sports celebrity partners. A bonus to a newly admitted partner can also occur when the book values of assets currently on the partnership’s books have a higher value than their fair market values. A bonus to a new admitted partner decreases (or debits) the capital balances of the old partners. The amount of the decrease depends on the income ratio defined by the old partnership agreement in place before the new partner’s admission. In our landscaping business example, suppose Remi receives a bonus based on his skills as a machine operator. Assume the following information ( Figure 15.7 ) for the partnership on the day he becomes a partner. To allocate the $10,000 bonus that each of the old partners will contribute to the new partner, Remi, make the following calculations. Dale: ( $10,000 × 50% ) = $5,000 Ciara: ( $10,000 × 50% ) = $5,000 Dale: ( $10,000 × 50% ) = $5,000 Ciara: ( $10,000 × 50% ) = $5,000 The journal entry to record Remi’s admission and the payment of his bonus in the partnership records is as follows: Withdrawal of Partner Now, let’s explore the opposite situation—when a partner withdraws from a partnership. Partners may withdraw by selling their equity in the business, through retirement, or upon death. The withdrawal of a partner, just like the admission of a new partner, dissolves the partnership, and a new agreement must be reached. As with a new partner, only the economic effect of the change in ownership is reflected on the books. When existing partners buy out a retiring partner, the case is the opposite of admitting a new partner, but the transaction is similar. The existing partners use personal assets to acquire the withdrawing partner’s equity and, as a result, the partnership’s assets are not affected. The only effect in the partnership’s records is the change in capital accounts. For example, assume that, after much discussion, Dale is ready to retire. Each partner has capital account balances of $60,000. Ciara and Remi agree to pay Dale $30,000 each to close out his partnership account. To record the withdrawal of Dale from the partnership, the journal entry is as follows: Note that there is no change to the net assets of Acorn Lawn & Hardscapes—only a change in the capital accounts. Ciara and Remi now have to create a new partnership agreement to reflect their new situation. Partnership Buys Out Withdrawing Partner When a partnership buys out a withdrawing partner, the terms of the buy-out should follow the partnership agreement. Using partnership assets to pay for a withdrawing partner is the opposite of having a new partner invest in the partnership. In accounting for the withdrawal by payment from partnership assets, the partnership should consider the difference, if any, between the agreed-upon buy-out dollar amount and the balance in the withdrawing partner’s capital account. That difference is a bonus to the retiring partner. This situation occurs when: The partnership’s fair market value of assets exceeds the book value. Goodwill resulting from the partnership has not been accounted for. The remaining partners urgently want the withdrawing partner to exit or want to show their appreciation of the partner’s contributions. The partnership debits (or reduces) the bonus from the remaining partners’ capital balances on the basis of their income ratio at the time of the buy-out. To illustrate, Acorn Lawn & Hardscapes is appreciative of the hard work that Dale has put into its success and would like to pay him a bonus. Dale, Ciara, and Remi each have capital account balances of $60,000 at the time of Dale’s retirement. Acorn Lawn & Hardscapes intends to pay Dale $80,000 for his interest. Ciara and Remi will do this as follows: Calculate the amount of the bonus. This is done by subtracting Dale’s capital account balance from the cash payment: ($80,000 – $60,000) = $20,000. Allocate the cost of the bonus to the remaining partners on the basis of their income ratio. This calculation comes to $10,000 each for Ciara and Remi ($20,000 × 50%). The journal entry to record Dale’s retirement from the partnership and the bonus payment to reflect his withdrawal is as shown: In some cases, the retiring partner may give a bonus to the remaining partners. This can happen when: Recorded assets are overvalued. The partnership is not performing well. The partner urgently wants to leave the partnership In these cases, the cash paid by the partnership to the retiring partner is less than the balance in his or her capital account. As a result, the other partners receive a bonus to their capital accounts based on the income-sharing ratio established prior to the withdrawal. As an example, each of three partners of Acorn Lawn & Hardscapes has a capital balance of $60,000. Dale has another opportunity and is eager to move on. He is willing to accept $50,000 cash in order to retire. The difference between this cash amount and Dale’s capital account is a bonus to the remaining partners. The bonus will be allocated to Ciara and Remi based on the income ratio at the time of Dale’s departure. The journal entry to record Dale’s withdrawal and the bonus to Ciara and Remi is as shown: When a partner passes away, the partnership dissolves. Most partnership agreements have provisions for the surviving partners to continue operating the partnership. Typically, a valuation is performed at the date of death, and the remaining partners settle with the deceased partner’s estate either directly with cash or through distribution of the partnership’s assets. 15.5 Discuss and Record Entries for the Dissolution of a Partnership Partnerships dissolve. Sometime the decision is made to close the business. Sometimes there is a bankruptcy. Partner negligence, retirement, death, poor cash flow, and change in business practices are just some of the reasons for closing down. Ethical Considerations Ethical Partnership Dissolution In most dissolutions of a partnership, the business partners need to decide what will happen to the partnership itself. A partnership may be dissolved, but that may not end business operations. If the partnership’s business operations are to continue, the partnership must decide what to do with its customers or clients, particularly those primarily served by a partner leaving the business. An ethical partnership will notify its customers and clients of the change and whether and how the partnership is going to continue as a business under a new partnership agreement. Partners who are unable to agree on how to notify their customers and clients should look to the Uniform Partnership Act, Article 8, which outlines the general obligations and duties of partners when a partnership is dissolved. A partner’s duties and obligation upon dissolution describe what the departing partner owes to the partnership and the other partners in duties of loyalty and care, which are the basic fiduciary duties of a partner prior to dissolution, as outlined in Section 409 of the Uniform Partnership Act. The one change upon dissolution is that “each partner’s duty not to compete ends when the partnership dissolves.” The Act states that “the dissolution of a partnership is the change in the relation of the partners caused by any partner ceasing to be associated in the carrying on as distinguished from the winding up of the business.” 1 This may not terminate the partnership’s business operations, but the partner’s obligations under the dissolved partnership agreement will end, regardless of how the remaining partners create a new partnership. 1 Uniform Law Commission. Uniform Partnership Act (1997) (Last Amended 2013). https://www.uniformlaws.org/viewdocument/final-act-with-comments-118?CommunityKey=52456941-7883-47a5-91b6-d2f086d0bb44&tab=librarydocuments The departure or removal of a partner or partners and the resulting creation of a new partnership may be tricky, because all original partners owe each other the duty of fairness and loyalty until the dissolution has been completed. All the partners, departing or otherwise, are required to behave in a fashion that does not hurt business operations and avoid putting their individual interests ahead of the interests of the soon-to-be-dissolved partnership. Once the partnership has been dissolved, the departing partners no longer have an obligation to their old business partners. Fundamentals of Partnership Dissolution The liquidation or dissolution process for partnerships is similar to the liquidation process for corporations. Over a period of time, the partnership’s non-cash assets are converted to cash, creditors are paid to the extent possible, and remaining funds, if any, are distributed to the partners. Partnership liquidations differ from corporate liquidations in some respects, however: General partners, as you may recall, have unlimited liability. Any general partner may be asked to contribute additional funds to the partnership if its assets are insufficient to satisfy creditors’ claims. If a general partner does not make good on his or her deficit capital balance, the remaining partners must absorb that deficit balance. Absorption of the partner’s deficit balance gives the absorbing partner legal recourse against the deficit partner. Recording the Dissolution Process As discussed above, the liquidation or dissolution of a partnership is synonymous with closing the business. This may occur due to mutual partner agreement to sell the business, the death of a partner, or bankruptcy. Before proceeding with liquidation, the partnership should complete the accounting cycle for its final operational period. This will require closing the books with only balance sheet accounts remaining. Once that process has been completed, four steps remain in the accounting for the liquidation, each requiring an accounting entry. They are: Step 1: Sell noncash assets for cash and recognize a gain or loss on realization . Realization is the sale of noncash assets for cash. Step 2: Allocate the gain or loss from realization to the partners based on their income ratios. Step 3: Pay partnership liabilities in cash. Step 4: Distribute any remaining cash to the partners on the basis of their capital balances. These steps must be performed in sequence. Partnerships must pay creditors prior to distributing funds to partners. At liquidation, some partners may have a deficiency in their capital accounts, or a debit balance. Let’s consider an example. Football Partnership is liquidated; its balance sheet after closing the books is shown in Figure 15.8 . The partners of Football Partnership agree to liquidate the partnership on the following terms: All the partnership assets will be sold to Hockey Partnership for $60,000 cash. The partnership will satisfy the liabilities. The income ratio will be 3:2:1 to partners Raven, Brown, and Eagle respectively. (Another way of saying this is 3/6:2/6:1/6.) The remaining cash will be distributed to the partners based on their capital account basis. The journal entry to record the sale of assets to Hockey Partnership (Step 1) is as shown: The journal entry to allocate the gain on realization among the partners’ capital accounts in the income ratio of 3:2:1 to Raven, Brown, and Eagle, respectively (Step 2), is as shown: The journal entry for Football Partnership to pay off the liabilities (Step 3) is as shown: The journal entry to distribute the remaining cash to the partners based on their capital account basis (Step 4) is as shown:
biology
Chapter Outline 6.1 Energy and Metabolism 6.2 Potential, Kinetic, Free, and Activation Energy 6.3 The Laws of Thermodynamics 6.4 ATP: Adenosine Triphosphate 6.5 Enzymes Introduction Virtually every task performed by living organisms requires energy. Energy is needed to perform heavy labor and exercise, but humans also use a great deal of energy while thinking, and even during sleep. In fact, the living cells of every organism constantly use energy. Nutrients and other molecules are imported, metabolized (broken down) and possibly synthesized into new molecules, modified if needed, transported around the cell, and may be distributed to the entire organism. For example, the large proteins that make up muscles are actively built from smaller molecules. Complex carbohydrates are broken down into simple sugars that the cell uses for energy. Just as energy is required to both build and demolish a building, energy is required for both the synthesis and breakdown of molecules. Additionally, signaling molecules such as hormones and neurotransmitters are transported between cells. Pathogenic bacteria and viruses are ingested and broken down by cells. Cells must also export waste and toxins to stay healthy, and many cells must swim or move surrounding materials via the beating motion of cellular appendages like cilia and flagella. The cellular processes listed above require a steady supply of energy. From where, and in what form, does this energy come? How do living cells obtain energy, and how do they use it? This chapter will discuss different forms of energy and the physical laws that govern energy transfer. This chapter will also describe how cells use energy and replenish it, and how chemical reactions in the cell are performed with great efficiency.
[ { "answer": { "ans_choice": 2, "ans_text": "glucose : ATP" }, "bloom": null, "hl_context": "Solar energy is required to synthesize a molecule of glucose during the reactions of photosynthesis . <hl> In photosynthesis , light energy from the sun is initially transformed into chemical energy that is temporally stored in the energy carrier molecules ATP and NADPH ( nicotinamide adenine dinucleotide phosphate ) . <hl> <hl> The stored energy in ATP and NADPH is then used later in photosynthesis to build one molecule of glucose from six molecules of CO 2 . <hl> This process is analogous to eating breakfast in the morning to acquire energy for your body that can be used later in the day . Under ideal conditions , energy from 18 molecules of ATP is required to synthesize one molecule of glucose during the reactions of photosynthesis . Glucose molecules can also be combined with and converted into other types of sugars . When sugars are consumed , molecules of glucose eventually make their way into each living cell of the organism . Inside the cell , each sugar molecule is broken down through a complex series of chemical reactions . The goal of these reactions is to harvest the energy stored inside the sugar molecules . The harvested energy is used to make high-energy ATP molecules , which can be used to perform work , powering many chemical reactions in the cell . The amount of energy needed to make one molecule of glucose from six molecules of carbon dioxide is 18 molecules of ATP and 12 molecules of NADPH ( each one of which is energetically equivalent to three molecules of ATP ) , or a total of 54 molecule equivalents required for the synthesis of one molecule of glucose . This process is a fundamental and efficient way for cells to generate the molecular energy that they require . The metabolism of sugar ( a simple carbohydrate ) is a classic example of the many cellular processes that use and produce energy . <hl> Living things consume sugar as a major energy source , because sugar molecules have a great deal of energy stored within their bonds . <hl> <hl> The breakdown of glucose , a simple sugar , is described by the equation : <hl>", "hl_sentences": "In photosynthesis , light energy from the sun is initially transformed into chemical energy that is temporally stored in the energy carrier molecules ATP and NADPH ( nicotinamide adenine dinucleotide phosphate ) . The stored energy in ATP and NADPH is then used later in photosynthesis to build one molecule of glucose from six molecules of CO 2 . Living things consume sugar as a major energy source , because sugar molecules have a great deal of energy stored within their bonds . The breakdown of glucose , a simple sugar , is described by the equation :", "question": { "cloze_format": "Energy is stored long-term in the bonds of _____ and used short-term to perform work from a(n) _____ molecule.", "normal_format": "In what bonds energy is stored for the long-term and is used short-term to perform work from what molecule? ", "question_choices": [ "ATP : glucose", "an anabolic molecule : catabolic molecule", "glucose : ATP", "a catabolic molecule : anabolic molecule" ], "question_id": "fs-id1786661", "question_text": "Energy is stored long-term in the bonds of _____ and used short-term to perform work from a(n) _____ molecule." }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 1, "ans_text": "Compare their reaction rates" }, "bloom": "2", "hl_context": "<hl> Since the rates of biochemical reactions are controlled by activation energy , and enzymes lower and determine activation energies for chemical reactions , the relative amounts and functioning of the variety of enzymes within a cell ultimately determine which reactions will proceed and at which rates . <hl> This determination is tightly controlled . In certain cellular environments , enzyme activity is partly controlled by environmental factors , like pH and temperature . There are other mechanisms through which cells control the activity of enzymes and determine the rates at which various biochemical reactions will occur . <hl> The activation energy of a particular reaction determines the rate at which it will proceed . <hl> <hl> The higher the activation energy , the slower the chemical reaction will be . <hl> The example of iron rusting illustrates an inherently slow reaction . This reaction occurs slowly over time because of its high E A . Additionally , the burning of many fuels , which is strongly exergonic , will take place at a negligible rate unless their activation energy is overcome by sufficient heat from a spark . Once they begin to burn , however , the chemical reactions release enough heat to continue the burning process , supplying the activation energy for surrounding fuel molecules . Like these reactions outside of cells , the activation energy for most cellular reactions is too high for heat energy to overcome at efficient rates . In other words , in order for important cellular reactions to occur at appreciable rates ( number of reactions per unit time ) , their activation energies must be lowered ( Figure 6.10 ); this is referred to as catalysis . This is a very good thing as far as living cells are concerned . Important macromolecules , such as proteins , DNA , and RNA , store considerable energy , and their breakdown is exergonic . If cellular temperatures alone provided enough heat energy for these exergonic reactions to overcome their activation barriers , the essential components of a cell would disintegrate .", "hl_sentences": "Since the rates of biochemical reactions are controlled by activation energy , and enzymes lower and determine activation energies for chemical reactions , the relative amounts and functioning of the variety of enzymes within a cell ultimately determine which reactions will proceed and at which rates . The activation energy of a particular reaction determines the rate at which it will proceed . The higher the activation energy , the slower the chemical reaction will be .", "question": { "cloze_format": "The best way to judge the relative activation energies between two given chemical reactions is to ___ .", "normal_format": "Which of the following is the best way to judge the relative activation energies between two given chemical reactions?", "question_choices": [ "Compare the ∆G values between the two reactions", "Compare their reaction rates", "Compare their ideal environmental conditions", "Compare the spontaneity between the two reactions" ], "question_id": "fs-id1772148", "question_text": "Which of the following is the best way to judge the relative activation energies between two given chemical reactions?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 3, "ans_text": "providing energy to coupled reactions" }, "bloom": null, "hl_context": "size 12 { { ATP } + H rSub { size 8{ 2 } } O ADP + P rSub { size 8{ i } } + { free energy } } { } Two prominent questions remain with regard to the use of ATP as an energy source . Exactly how much free energy is released with the hydrolysis of ATP , and how is that free energy used to do cellular work ? The calculated ∆ G for the hydrolysis of one mole of ATP into ADP and P i is − 7.3 kcal / mole ( − 30.5 kJ / mol ) . Since this calculation is true under standard conditions , it would be expected that a different value exists under cellular conditions . In fact , the ∆ G for the hydrolysis of one mole of ATP in a living cell is almost double the value at standard conditions : – 14 kcal / mol ( − 57 kJ / mol ) . ATP is a highly unstable molecule . Unless quickly used to perform work , ATP spontaneously dissociates into ADP + P i , and the free energy released during this process is lost as heat . <hl> The second question posed above , that is , how the energy released by ATP hydrolysis is used to perform work inside the cell , depends on a strategy called energy coupling . <hl> Cells couple the exergonic reaction of ATP hydrolysis with endergonic reactions , allowing them to proceed . One example of energy coupling using ATP involves a transmembrane ion pump that is extremely important for cellular function . This sodium-potassium pump ( Na + / K + pump ) drives sodium out of the cell and potassium into the cell ( Figure 6.14 ) . A large percentage of a cell ’ s ATP is spent powering this pump , because cellular processes bring a great deal of sodium into the cell and potassium out of the cell . The pump works constantly to stabilize cellular concentrations of sodium and potassium . In order for the pump to turn one cycle ( exporting three Na + ions and importing two K + ions ) , one molecule of ATP must be hydrolyzed . When ATP is hydrolyzed , its gamma phosphate doesn ’ t simply float away , but is actually transferred onto the pump protein . This process of a phosphate group binding to a molecule is called phosphorylation . As with most cases of ATP hydrolysis , a phosphate from ATP is transferred onto another molecule . In a phosphorylated state , the Na + / K + pump has more free energy and is triggered to undergo a conformational change . This change allows it to release Na + to the outside of the cell . It then binds extracellular K + , which , through another conformational change , causes the phosphate to detach from the pump . This release of phosphate triggers the K + to be released to the inside of the cell . Essentially , the energy released from the hydrolysis of ATP is coupled with the energy required to power the pump and transport Na + and K + ions . <hl> ATP performs cellular work using this basic form of energy coupling through phosphorylation . <hl>", "hl_sentences": "The second question posed above , that is , how the energy released by ATP hydrolysis is used to perform work inside the cell , depends on a strategy called energy coupling . ATP performs cellular work using this basic form of energy coupling through phosphorylation .", "question": { "cloze_format": "The energy released by the hydrolysis of ATP is ___.", "normal_format": "What is the energy released by the hydrolysis of ATP?", "question_choices": [ "primarily stored between the alpha and beta phosphates", "equal to −57 kcal/mol", "harnessed as heat energy by the cell to perform work", "providing energy to coupled reactions" ], "question_id": "fs-id1547306", "question_text": "The energy released by the hydrolysis of ATP is" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 0, "ans_text": "They increase ∆G of reactions" }, "bloom": null, "hl_context": "A substance that helps a chemical reaction to occur is a catalyst , and the special molecules that catalyze biochemical reactions are called enzymes . Almost all enzymes are proteins , made up of chains of amino acids , and they perform the critical task of lowering the activation energies of chemical reactions inside the cell . Enzymes do this by binding to the reactant molecules , and holding them in such a way as to make the chemical bond-breaking and bond-forming processes take place more readily . <hl> It is important to remember that enzymes don ’ t change the ∆ G of a reaction . <hl> In other words , they don ’ t change whether a reaction is exergonic ( spontaneous ) or endergonic . This is because they don ’ t change the free energy of the reactants or products . They only reduce the activation energy required to reach the transition state ( Figure 6.15 ) .", "hl_sentences": "It is important to remember that enzymes don ’ t change the ∆ G of a reaction .", "question": { "cloze_format": "A false statement about enzymes is that ___ .", "normal_format": "Which of the following is not true about enzymes?", "question_choices": [ "They increase ∆G of reactions", "They are usually made of amino acids", "They lower the activation energy of chemical reactions", "Each one is specific to the particular substrate(s) to which it binds" ], "question_id": "fs-id1724046", "question_text": "Which of the following is not true about enzymes:" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 2, "ans_text": "Binds to an enzyme away from the active site and changes the conformation of the active site, decreasing its affinity for the substrate" }, "bloom": "2", "hl_context": "<hl> Some inhibitor molecules bind to enzymes in a location where their binding induces a conformational change that reduces the affinity of the enzyme for its substrate . <hl> <hl> This type of inhibition is called allosteric inhibition ( Figure 6.18 ) . <hl> Most allosterically regulated enzymes are made up of more than one polypeptide , meaning that they have more than one protein subunit . <hl> When an allosteric inhibitor binds to an enzyme , all active sites on the protein subunits are changed slightly such that they bind their substrates with less efficiency . <hl> There are allosteric activators as well as inhibitors . Allosteric activators bind to locations on an enzyme away from the active site , inducing a conformational change that increases the affinity of the enzyme ’ s active site ( s ) for its substrate ( s ) .", "hl_sentences": "Some inhibitor molecules bind to enzymes in a location where their binding induces a conformational change that reduces the affinity of the enzyme for its substrate . This type of inhibition is called allosteric inhibition ( Figure 6.18 ) . When an allosteric inhibitor binds to an enzyme , all active sites on the protein subunits are changed slightly such that they bind their substrates with less efficiency .", "question": { "cloze_format": "An allosteric inhibitor ___.", "normal_format": "An allosteric inhibitor does which of the following?", "question_choices": [ "Binds to an enzyme away from the active site and changes the conformation of the active site, increasing its affinity for substrate binding", "Binds to the active site and blocks it from binding substrate", "Binds to an enzyme away from the active site and changes the conformation of the active site, decreasing its affinity for the substrate", "Binds directly to the active site and mimics the substrate" ], "question_id": "fs-id2229279", "question_text": "An allosteric inhibitor does which of the following?" }, "references_are_paraphrase": null } ]
6
6.1 Energy and Metabolism Learning Objectives By the end of this section, you will be able to: Explain what metabolic pathways are and describe the two major types of metabolic pathways Discuss how chemical reactions play a role in energy transfer Scientists use the term bioenergetics to discuss the concept of energy flow ( Figure 6.2 ) through living systems, such as cells. Cellular processes such as the building and breaking down of complex molecules occur through stepwise chemical reactions. Some of these chemical reactions are spontaneous and release energy, whereas others require energy to proceed. Just as living things must continually consume food to replenish what has been used, cells must continually produce more energy to replenish that used by the many energy-requiring chemical reactions that constantly take place. All of the chemical reactions that take place inside cells, including those that use energy and those that release energy, are the cell’s metabolism . Metabolism of Carbohydrates The metabolism of sugar (a simple carbohydrate) is a classic example of the many cellular processes that use and produce energy. Living things consume sugar as a major energy source, because sugar molecules have a great deal of energy stored within their bonds. The breakdown of glucose, a simple sugar, is described by the equation: C 6 H 12 O 6 + 6O 2 → 6 CO 2 + 6H 2 O + energy C 6 H 12 O 6 + 6O 2 → 6 CO 2 + 6H 2 O + energy size 12{C rSub { size 8{6} } H rSub { size 8{12} } O rSub { size 8{2} } } {} Carbohydrates that are consumed have their origins in photosynthesizing organisms like plants ( Figure 6.3 ). During photosynthesis, plants use the energy of sunlight to convert carbon dioxide gas (CO 2 ) into sugar molecules, like glucose (C 6 H 12 O 6 ). Because this process involves synthesizing a larger, energy-storing molecule, it requires an input of energy to proceed. The synthesis of glucose is described by this equation (notice that it is the reverse of the previous equation): 6CO 2 + 6H 2 O + energy → C 6 H 12 O 6 + 6O 2 6CO 2 + 6H 2 O + energy → C 6 H 12 O 6 + 6O 2 size 12{C rSub { size 8{6} } H rSub { size 8{12} } O rSub { size 8{2} } } {} During the chemical reactions of photosynthesis, energy is provided in the form of a very high-energy molecule called ATP, or adenosine triphosphate, which is the primary energy currency of all cells. Just as the dollar is used as currency to buy goods, cells use molecules of ATP as energy currency to perform immediate work. The sugar (glucose) is stored as starch or glycogen. Energy-storing polymers like these are broken down into glucose to supply molecules of ATP. Solar energy is required to synthesize a molecule of glucose during the reactions of photosynthesis. In photosynthesis, light energy from the sun is initially transformed into chemical energy that is temporally stored in the energy carrier molecules ATP and NADPH (nicotinamide adenine dinucleotide phosphate). The stored energy in ATP and NADPH is then used later in photosynthesis to build one molecule of glucose from six molecules of CO 2 . This process is analogous to eating breakfast in the morning to acquire energy for your body that can be used later in the day. Under ideal conditions, energy from 18 molecules of ATP is required to synthesize one molecule of glucose during the reactions of photosynthesis. Glucose molecules can also be combined with and converted into other types of sugars. When sugars are consumed, molecules of glucose eventually make their way into each living cell of the organism. Inside the cell, each sugar molecule is broken down through a complex series of chemical reactions. The goal of these reactions is to harvest the energy stored inside the sugar molecules. The harvested energy is used to make high-energy ATP molecules, which can be used to perform work, powering many chemical reactions in the cell. The amount of energy needed to make one molecule of glucose from six molecules of carbon dioxide is 18 molecules of ATP and 12 molecules of NADPH (each one of which is energetically equivalent to three molecules of ATP), or a total of 54 molecule equivalents required for the synthesis of one molecule of glucose. This process is a fundamental and efficient way for cells to generate the molecular energy that they require. Metabolic Pathways The processes of making and breaking down sugar molecules illustrate two types of metabolic pathways. A metabolic pathway is a series of interconnected biochemical reactions that convert a substrate molecule or molecules, step-by-step, through a series of metabolic intermediates, eventually yielding a final product or products. In the case of sugar metabolism, the first metabolic pathway synthesized sugar from smaller molecules, and the other pathway broke sugar down into smaller molecules. These two opposite processes—the first requiring energy and the second producing energy—are referred to as anabolic (building) and catabolic (breaking down) pathways, respectively. Consequently, metabolism is composed of building (anabolism) and degradation (catabolism). Evolution Connection Evolution of Metabolic Pathways There is more to the complexity of metabolism than understanding the metabolic pathways alone. Metabolic complexity varies from organism to organism. Photosynthesis is the primary pathway in which photosynthetic organisms like plants (the majority of global synthesis is done by planktonic algae) harvest the sun’s energy and convert it into carbohydrates. The by-product of photosynthesis is oxygen, required by some cells to carry out cellular respiration. During cellular respiration, oxygen aids in the catabolic breakdown of carbon compounds, like carbohydrates. Among the products of this catabolism are CO 2 and ATP. In addition, some eukaryotes perform catabolic processes without oxygen (fermentation); that is, they perform or use anaerobic metabolism. Organisms probably evolved anaerobic metabolism to survive (living organisms came into existence about 3.8 billion years ago, when the atmosphere lacked oxygen). Despite the differences between organisms and the complexity of metabolism, researchers have found that all branches of life share some of the same metabolic pathways, suggesting that all organisms evolved from the same ancient common ancestor ( Figure 6.4 ). Evidence indicates that over time, the pathways diverged, adding specialized enzymes to allow organisms to better adapt to their environment, thus increasing their chance to survive. However, the underlying principle remains that all organisms must harvest energy from their environment and convert it to ATP to carry out cellular functions. Anabolic and Catabolic Pathways Anabolic pathways require an input of energy to synthesize complex molecules from simpler ones. Synthesizing sugar from CO 2 is one example. Other examples are the synthesis of large proteins from amino acid building blocks, and the synthesis of new DNA strands from nucleic acid building blocks. These biosynthetic processes are critical to the life of the cell, take place constantly, and demand energy provided by ATP and other high-energy molecules like NADH (nicotinamide adenine dinucleotide) and NADPH ( Figure 6.5 ). ATP is an important molecule for cells to have in sufficient supply at all times. The breakdown of sugars illustrates how a single molecule of glucose can store enough energy to make a great deal of ATP, 36 to 38 molecules. This is a catabolic pathway. Catabolic pathways involve the degradation (or breakdown) of complex molecules into simpler ones. Molecular energy stored in the bonds of complex molecules is released in catabolic pathways and harvested in such a way that it can be used to produce ATP. Other energy-storing molecules, such as fats, are also broken down through similar catabolic reactions to release energy and make ATP ( Figure 6.5 ). It is important to know that the chemical reactions of metabolic pathways don’t take place spontaneously. Each reaction step is facilitated, or catalyzed, by a protein called an enzyme. Enzymes are important for catalyzing all types of biological reactions—those that require energy as well as those that release energy. 6.2 Potential, Kinetic, Free, and Activation Energy Learning Objectives By the end of this section, you will be able to: Define “energy” Explain the difference between kinetic and potential energy Discuss the concepts of free energy and activation energy Describe endergonic and exergonic reactions Energy is defined as the ability to do work. As you’ve learned, energy exists in different forms. For example, electrical energy, light energy, and heat energy are all different types of energy. While these are all familiar types of energy that one can see or feel, there is another type of energy that is much less tangible. This energy is associated with something as simple as an object held above the ground. In order to appreciate the way energy flows into and out of biological systems, it is important to understand more about the different types of energy that exist in the physical world. Types of Energy When an object is in motion, there is energy associated with that object. In the example of an airplane in flight, there is a great deal of energy associated with the motion of the airplane. This is because moving objects are capable of enacting a change, or doing work. Think of a wrecking ball. Even a slow-moving wrecking ball can do a great deal of damage to other objects. However, a wrecking ball that is not in motion is incapable of performing work. Energy associated with objects in motion is called kinetic energy . A speeding bullet, a walking person, the rapid movement of molecules in the air (which produces heat), and electromagnetic radiation like light all have kinetic energy. Now what if that same motionless wrecking ball is lifted two stories above a car with a crane? If the suspended wrecking ball is unmoving, is there energy associated with it? The answer is yes. The suspended wrecking ball has energy associated with it that is fundamentally different from the kinetic energy of objects in motion. This form of energy results from the fact that there is the potential for the wrecking ball to do work. If it is released, indeed it would do work. Because this type of energy refers to the potential to do work, it is called potential energy . Objects transfer their energy between kinetic and potential in the following way: As the wrecking ball hangs motionless, it has 0 kinetic and 100 percent potential energy. Once it is released, its kinetic energy begins to increase because it builds speed due to gravity. At the same time, as it nears the ground, it loses potential energy. Somewhere mid-fall it has 50 percent kinetic and 50 percent potential energy. Just before it hits the ground, the ball has nearly lost its potential energy and has near-maximal kinetic energy. Other examples of potential energy include the energy of water held behind a dam ( Figure 6.6 ), or a person about to skydive out of an airplane. Potential energy is not only associated with the location of matter (such as a child sitting on a tree branch), but also with the structure of matter. A spring on the ground has potential energy if it is compressed; so does a rubber band that is pulled taut. The very existence of living cells relies heavily on structural potential energy. On a chemical level, the bonds that hold the atoms of molecules together have potential energy. Remember that anabolic cellular pathways require energy to synthesize complex molecules from simpler ones, and catabolic pathways release energy when complex molecules are broken down. The fact that energy can be released by the breakdown of certain chemical bonds implies that those bonds have potential energy. In fact, there is potential energy stored within the bonds of all the food molecules we eat, which is eventually harnessed for use. This is because these bonds can release energy when broken. The type of potential energy that exists within chemical bonds, and is released when those bonds are broken, is called chemical energy ( Figure 6.7 ). Chemical energy is responsible for providing living cells with energy from food. The release of energy is brought about by breaking the molecular bonds within fuel molecules. Link to Learning Visit this site and select “A simple pendulum” on the menu (under “Harmonic Motion”) to see the shifting kinetic (K) and potential energy (U) of a pendulum in motion. Free Energy After learning that chemical reactions release energy when energy-storing bonds are broken, an important next question is how is the energy associated with chemical reactions quantified and expressed? How can the energy released from one reaction be compared to that of another reaction? A measurement of free energy is used to quantitate these energy transfers. Free energy is called Gibbs free energy (abbreviated with the letter G) after Josiah Willard Gibbs, the scientist who developed the measurement. Recall that according to the second law of thermodynamics, all energy transfers involve the loss of some amount of energy in an unusable form such as heat, resulting in entropy. Gibbs free energy specifically refers to the energy associated with a chemical reaction that is available after entropy is accounted for. In other words, Gibbs free energy is usable energy, or energy that is available to do work. Every chemical reaction involves a change in free energy, called delta G (∆G). The change in free energy can be calculated for any system that undergoes such a change, such as a chemical reaction. To calculate ∆G, subtract the amount of energy lost to entropy (denoted as ∆S) from the total energy change of the system. This total energy change in the system is called enthalpy and is denoted as ∆H . The formula for calculating ∆G is as follows, where the symbol T refers to absolute temperature in Kelvin (degrees Celsius + 273): Δ G = Δ H − T Δ S Δ G = Δ H − T Δ S The standard free energy change of a chemical reaction is expressed as an amount of energy per mole of the reaction product (either in kilojoules or kilocalories, kJ/mol or kcal/mol; 1 kJ = 0.239 kcal) under standard pH, temperature, and pressure conditions. Standard pH, temperature, and pressure conditions are generally calculated at pH 7.0 in biological systems, 25 degrees Celsius, and 100 kilopascals (1 atm pressure), respectively. It is important to note that cellular conditions vary considerably from these standard conditions, and so standard calculated ∆G values for biological reactions will be different inside the cell. Endergonic Reactions and Exergonic Reactions If energy is released during a chemical reaction, then the resulting value from the above equation will be a negative number. In other words, reactions that release energy have a ∆G < 0. A negative ∆G also means that the products of the reaction have less free energy than the reactants, because they gave off some free energy during the reaction. Reactions that have a negative ∆G and consequently release free energy are called exergonic reactions . Think: ex ergonic means energy is ex iting the system. These reactions are also referred to as spontaneous reactions, because they can occur without the addition of energy into the system. Understanding which chemical reactions are spontaneous and release free energy is extremely useful for biologists, because these reactions can be harnessed to perform work inside the cell. An important distinction must be drawn between the term spontaneous and the idea of a chemical reaction that occurs immediately. Contrary to the everyday use of the term, a spontaneous reaction is not one that suddenly or quickly occurs. The rusting of iron is an example of a spontaneous reaction that occurs slowly, little by little, over time. If a chemical reaction requires an input of energy rather than releasing energy, then the ∆G for that reaction will be a positive value. In this case, the products have more free energy than the reactants. Thus, the products of these reactions can be thought of as energy-storing molecules. These chemical reactions are called endergonic reactions , and they are non-spontaneous. An endergonic reaction will not take place on its own without the addition of free energy. Let’s revisit the example of the synthesis and breakdown of the food molecule, glucose. Remember that the building of complex molecules, such as sugars, from simpler ones is an anabolic process and requires energy. Therefore, the chemical reactions involved in anabolic processes are endergonic reactions. On the other hand, the catabolic process of breaking sugar down into simpler molecules releases energy in a series of exergonic reactions. Like the example of rust above, the breakdown of sugar involves spontaneous reactions, but these reactions don’t occur instantaneously. Figure 6.8 shows some other examples of endergonic and exergonic reactions. Later sections will provide more information about what else is required to make even spontaneous reactions happen more efficiently. Visual Connection Look at each of the processes shown, and decide if it is endergonic or exergonic. In each case, does enthalpy increase or decrease, and does entropy increase or decrease? An important concept in the study of metabolism and energy is that of chemical equilibrium. Most chemical reactions are reversible. They can proceed in both directions, releasing energy into their environment in one direction, and absorbing it from the environment in the other direction ( Figure 6.9 ). The same is true for the chemical reactions involved in cell metabolism, such as the breaking down and building up of proteins into and from individual amino acids, respectively. Reactants within a closed system will undergo chemical reactions in both directions until a state of equilibrium is reached. This state of equilibrium is one of the lowest possible free energy and a state of maximal entropy. Energy must be put into the system to push the reactants and products away from a state of equilibrium. Either reactants or products must be added, removed, or changed. If a cell were a closed system, its chemical reactions would reach equilibrium, and it would die because there would be insufficient free energy left to perform the work needed to maintain life. In a living cell, chemical reactions are constantly moving towards equilibrium, but never reach it. This is because a living cell is an open system. Materials pass in and out, the cell recycles the products of certain chemical reactions into other reactions, and chemical equilibrium is never reached. In this way, living organisms are in a constant energy-requiring, uphill battle against equilibrium and entropy. This constant supply of energy ultimately comes from sunlight, which is used to produce nutrients in the process of photosynthesis. Activation Energy There is another important concept that must be considered regarding endergonic and exergonic reactions. Even exergonic reactions require a small amount of energy input to get going before they can proceed with their energy-releasing steps. These reactions have a net release of energy, but still require some energy in the beginning. This small amount of energy input necessary for all chemical reactions to occur is called the activation energy (or free energy of activation) and is abbreviated E A ( Figure 6.10 ). Why would an energy-releasing, negative ∆G reaction actually require some energy to proceed? The reason lies in the steps that take place during a chemical reaction. During chemical reactions, certain chemical bonds are broken and new ones are formed. For example, when a glucose molecule is broken down, bonds between the carbon atoms of the molecule are broken. Since these are energy-storing bonds, they release energy when broken. However, to get them into a state that allows the bonds to break, the molecule must be somewhat contorted. A small energy input is required to achieve this contorted state. This contorted state is called the transition state , and it is a high-energy, unstable state. For this reason, reactant molecules don’t last long in their transition state, but very quickly proceed to the next steps of the chemical reaction. Free energy diagrams illustrate the energy profiles for a given reaction. Whether the reaction is exergonic or endergonic determines whether the products in the diagram will exist at a lower or higher energy state than both the reactants and the products. However, regardless of this measure, the transition state of the reaction exists at a higher energy state than the reactants, and thus, E A is always positive. Link to Learning Watch an animation of the move from free energy to transition state at this site. Where does the activation energy required by chemical reactants come from? The source of the activation energy needed to push reactions forward is typically heat energy from the surroundings. Heat energy (the total bond energy of reactants or products in a chemical reaction) speeds up the motion of molecules, increasing the frequency and force with which they collide; it also moves atoms and bonds within the molecule slightly, helping them reach their transition state. For this reason, heating up a system will cause chemical reactants within that system to react more frequently. Increasing the pressure on a system has the same effect. Once reactants have absorbed enough heat energy from their surroundings to reach the transition state, the reaction will proceed. The activation energy of a particular reaction determines the rate at which it will proceed. The higher the activation energy, the slower the chemical reaction will be. The example of iron rusting illustrates an inherently slow reaction. This reaction occurs slowly over time because of its high E A . Additionally, the burning of many fuels, which is strongly exergonic, will take place at a negligible rate unless their activation energy is overcome by sufficient heat from a spark. Once they begin to burn, however, the chemical reactions release enough heat to continue the burning process, supplying the activation energy for surrounding fuel molecules. Like these reactions outside of cells, the activation energy for most cellular reactions is too high for heat energy to overcome at efficient rates. In other words, in order for important cellular reactions to occur at appreciable rates (number of reactions per unit time), their activation energies must be lowered ( Figure 6.10 ); this is referred to as catalysis. This is a very good thing as far as living cells are concerned. Important macromolecules, such as proteins, DNA, and RNA, store considerable energy, and their breakdown is exergonic. If cellular temperatures alone provided enough heat energy for these exergonic reactions to overcome their activation barriers, the essential components of a cell would disintegrate. Visual Connection If no activation energy were required to break down sucrose (table sugar), would you be able to store it in a sugar bowl? 6.3 The Laws of Thermodynamics Learning Objectives By the end of this section, you will be able to: Discuss the concept of entropy Explain the first and second laws of thermodynamics Thermodynamics refers to the study of energy and energy transfer involving physical matter. The matter and its environment relevant to a particular case of energy transfer are classified as a system, and everything outside of that system is called the surroundings. For instance, when heating a pot of water on the stove, the system includes the stove, the pot, and the water. Energy is transferred within the system (between the stove, pot, and water). There are two types of systems: open and closed. An open system is one in which energy can be transferred between the system and its surroundings. The stovetop system is open because heat can be lost into the air. A closed system is one that cannot transfer energy to its surroundings. Biological organisms are open systems. Energy is exchanged between them and their surroundings, as they consume energy-storing molecules and release energy to the environment by doing work. Like all things in the physical world, energy is subject to the laws of physics. The laws of thermodynamics govern the transfer of energy in and among all systems in the universe. The First Law of Thermodynamics The first law of thermodynamics deals with the total amount of energy in the universe. It states that this total amount of energy is constant. In other words, there has always been, and always will be, exactly the same amount of energy in the universe. Energy exists in many different forms. According to the first law of thermodynamics, energy may be transferred from place to place or transformed into different forms, but it cannot be created or destroyed. The transfers and transformations of energy take place around us all the time. Light bulbs transform electrical energy into light energy. Gas stoves transform chemical energy from natural gas into heat energy. Plants perform one of the most biologically useful energy transformations on earth: that of converting the energy of sunlight into the chemical energy stored within organic molecules ( Figure 6.2 ). Some examples of energy transformations are shown in Figure 6.11 . The challenge for all living organisms is to obtain energy from their surroundings in forms that they can transfer or transform into usable energy to do work. Living cells have evolved to meet this challenge very well. Chemical energy stored within organic molecules such as sugars and fats is transformed through a series of cellular chemical reactions into energy within molecules of ATP. Energy in ATP molecules is easily accessible to do work. Examples of the types of work that cells need to do include building complex molecules, transporting materials, powering the beating motion of cilia or flagella, contracting muscle fibers to create movement, and reproduction. The Second Law of Thermodynamics A living cell’s primary tasks of obtaining, transforming, and using energy to do work may seem simple. However, the second law of thermodynamics explains why these tasks are harder than they appear. None of the energy transfers we’ve discussed, along with all energy transfers and transformations in the universe, is completely efficient. In every energy transfer, some amount of energy is lost in a form that is unusable. In most cases, this form is heat energy. Thermodynamically, heat energy is defined as the energy transferred from one system to another that is not doing work. For example, when an airplane flies through the air, some of the energy of the flying plane is lost as heat energy due to friction with the surrounding air. This friction actually heats the air by temporarily increasing the speed of air molecules. Likewise, some energy is lost as heat energy during cellular metabolic reactions. This is good for warm-blooded creatures like us, because heat energy helps to maintain our body temperature. Strictly speaking, no energy transfer is completely efficient, because some energy is lost in an unusable form. An important concept in physical systems is that of order and disorder (also known as randomness). The more energy that is lost by a system to its surroundings, the less ordered and more random the system is. Scientists refer to the measure of randomness or disorder within a system as entropy . High entropy means high disorder and low energy ( Figure 6.12 ). To better understand entropy, think of a student’s bedroom. If no energy or work were put into it, the room would quickly become messy. It would exist in a very disordered state, one of high entropy. Energy must be put into the system, in the form of the student doing work and putting everything away, in order to bring the room back to a state of cleanliness and order. This state is one of low entropy. Similarly, a car or house must be constantly maintained with work in order to keep it in an ordered state. Left alone, the entropy of the house or car gradually increases through rust and degradation. Molecules and chemical reactions have varying amounts of entropy as well. For example, as chemical reactions reach a state of equilibrium, entropy increases, and as molecules at a high concentration in one place diffuse and spread out, entropy also increases. Scientific Method Connection Transfer of Energy and the Resulting Entropy Set up a simple experiment to understand how energy is transferred and how a change in entropy results. Take a block of ice. This is water in solid form, so it has a high structural order. This means that the molecules cannot move very much and are in a fixed position. The temperature of the ice is 0°C. As a result, the entropy of the system is low. Allow the ice to melt at room temperature. What is the state of molecules in the liquid water now? How did the energy transfer take place? Is the entropy of the system higher or lower? Why? Heat the water to its boiling point. What happens to the entropy of the system when the water is heated? All physical systems can be thought of in this way: Living things are highly ordered, requiring constant energy input to be maintained in a state of low entropy. As living systems take in energy-storing molecules and transform them through chemical reactions, they lose some amount of usable energy in the process, because no reaction is completely efficient. They also produce waste and by-products that aren’t useful energy sources. This process increases the entropy of the system’s surroundings. Since all energy transfers result in the loss of some usable energy, the second law of thermodynamics states that every energy transfer or transformation increases the entropy of the universe. Even though living things are highly ordered and maintain a state of low entropy, the entropy of the universe in total is constantly increasing due to the loss of usable energy with each energy transfer that occurs. Essentially, living things are in a continuous uphill battle against this constant increase in universal entropy. 6.4 ATP: Adenosine Triphosphate Learning Objectives By the end of this section, you will be able to: Explain the role of ATP as the cellular energy currency Describe how energy is released through hydrolysis of ATP Even exergonic, energy-releasing reactions require a small amount of activation energy in order to proceed. However, consider endergonic reactions, which require much more energy input, because their products have more free energy than their reactants. Within the cell, where does energy to power such reactions come from? The answer lies with an energy-supplying molecule called adenosine triphosphate , or ATP . ATP is a small, relatively simple molecule ( Figure 6.13 ), but within some of its bonds, it contains the potential for a quick burst of energy that can be harnessed to perform cellular work. This molecule can be thought of as the primary energy currency of cells in much the same way that money is the currency that people exchange for things they need. ATP is used to power the majority of energy-requiring cellular reactions. As its name suggests, adenosine triphosphate is comprised of adenosine bound to three phosphate groups ( Figure 6.13 ). Adenosine is a nucleoside consisting of the nitrogenous base adenine and a five-carbon sugar, ribose. The three phosphate groups, in order of closest to furthest from the ribose sugar, are labeled alpha, beta, and gamma. Together, these chemical groups constitute an energy powerhouse. However, not all bonds within this molecule exist in a particularly high-energy state. Both bonds that link the phosphates are equally high-energy bonds ( phosphoanhydride bonds ) that, when broken, release sufficient energy to power a variety of cellular reactions and processes. These high-energy bonds are the bonds between the second and third (or beta and gamma) phosphate groups and between the first and second phosphate groups. The reason that these bonds are considered “high-energy” is because the products of such bond breaking—adenosine diphosphate (ADP) and one inorganic phosphate group (P i )—have considerably lower free energy than the reactants: ATP and a water molecule. Because this reaction takes place with the use of a water molecule, it is considered a hydrolysis reaction. In other words, ATP is hydrolyzed into ADP in the following reaction: ATP + H 2 O → ADP + P i + free energy ATP + H 2 O → ADP + P i + free energy size 12{{ATP} + H rSub { size 8{2} } O ADP + P rSub { size 8{i}} + {free energy} } {} Like most chemical reactions, the hydrolysis of ATP to ADP is reversible. The reverse reaction regenerates ATP from ADP + P i . Indeed, cells rely on the regeneration of ATP just as people rely on the regeneration of spent money through some sort of income. Since ATP hydrolysis releases energy, ATP regeneration must require an input of free energy. The formation of ATP is expressed in this equation: ADP + P i + free energy → ATP + H 2 O ADP + P i + free energy → ATP + H 2 O size 12{{ATP} + H rSub { size 8{2} } O ADP + P rSub { size 8{i}} + {free energy} } {} Two prominent questions remain with regard to the use of ATP as an energy source. Exactly how much free energy is released with the hydrolysis of ATP, and how is that free energy used to do cellular work? The calculated ∆G for the hydrolysis of one mole of ATP into ADP and P i is −7.3 kcal/mole (−30.5 kJ/mol). Since this calculation is true under standard conditions, it would be expected that a different value exists under cellular conditions. In fact, the ∆G for the hydrolysis of one mole of ATP in a living cell is almost double the value at standard conditions: –14 kcal/mol (−57 kJ/mol). ATP is a highly unstable molecule. Unless quickly used to perform work, ATP spontaneously dissociates into ADP + P i , and the free energy released during this process is lost as heat. The second question posed above, that is, how the energy released by ATP hydrolysis is used to perform work inside the cell, depends on a strategy called energy coupling. Cells couple the exergonic reaction of ATP hydrolysis with endergonic reactions, allowing them to proceed. One example of energy coupling using ATP involves a transmembrane ion pump that is extremely important for cellular function. This sodium-potassium pump (Na + /K + pump) drives sodium out of the cell and potassium into the cell ( Figure 6.14 ). A large percentage of a cell’s ATP is spent powering this pump, because cellular processes bring a great deal of sodium into the cell and potassium out of the cell. The pump works constantly to stabilize cellular concentrations of sodium and potassium. In order for the pump to turn one cycle (exporting three Na+ ions and importing two K + ions), one molecule of ATP must be hydrolyzed. When ATP is hydrolyzed, its gamma phosphate doesn’t simply float away, but is actually transferred onto the pump protein. This process of a phosphate group binding to a molecule is called phosphorylation. As with most cases of ATP hydrolysis, a phosphate from ATP is transferred onto another molecule. In a phosphorylated state, the Na + /K + pump has more free energy and is triggered to undergo a conformational change. This change allows it to release Na + to the outside of the cell. It then binds extracellular K + , which, through another conformational change, causes the phosphate to detach from the pump. This release of phosphate triggers the K + to be released to the inside of the cell. Essentially, the energy released from the hydrolysis of ATP is coupled with the energy required to power the pump and transport Na + and K + ions. ATP performs cellular work using this basic form of energy coupling through phosphorylation. Visual Connection The hydrolysis of one ATP molecule releases 7.3 kcal/mol of energy (∆G = −7.3 kcal/mol of energy). If it takes 2.1 kcal/mol of energy to move one Na + across the membrane (∆G = +2.1 kcal/mol of energy), how many sodium ions could be moved by the hydrolysis of one ATP molecule? Often during cellular metabolic reactions, such as the synthesis and breakdown of nutrients, certain molecules must be altered slightly in their conformation to become substrates for the next step in the reaction series. One example is during the very first steps of cellular respiration, when a molecule of the sugar glucose is broken down in the process of glycolysis. In the first step of this process, ATP is required for the phosphorylation of glucose, creating a high-energy but unstable intermediate. This phosphorylation reaction powers a conformational change that allows the phosphorylated glucose molecule to be converted to the phosphorylated sugar fructose. Fructose is a necessary intermediate for glycolysis to move forward. Here, the exergonic reaction of ATP hydrolysis is coupled with the endergonic reaction of converting glucose into a phosphorylated intermediate in the pathway. Once again, the energy released by breaking a phosphate bond within ATP was used for the phosphorylation of another molecule, creating an unstable intermediate and powering an important conformational change. Link to Learning See an interactive animation of the ATP-producing glycolysis process at this site . 6.5 Enzymes Learning Objectives By the end of this section, you will be able to: Describe the role of enzymes in metabolic pathways Explain how enzymes function as molecular catalysts Discuss enzyme regulation by various factors A substance that helps a chemical reaction to occur is a catalyst, and the special molecules that catalyze biochemical reactions are called enzymes. Almost all enzymes are proteins, made up of chains of amino acids, and they perform the critical task of lowering the activation energies of chemical reactions inside the cell. Enzymes do this by binding to the reactant molecules, and holding them in such a way as to make the chemical bond-breaking and bond-forming processes take place more readily. It is important to remember that enzymes don’t change the ∆G of a reaction. In other words, they don’t change whether a reaction is exergonic (spontaneous) or endergonic. This is because they don’t change the free energy of the reactants or products. They only reduce the activation energy required to reach the transition state ( Figure 6.15 ). Enzyme Active Site and Substrate Specificity The chemical reactants to which an enzyme binds are the enzyme’s substrates . There may be one or more substrates, depending on the particular chemical reaction. In some reactions, a single-reactant substrate is broken down into multiple products. In others, two substrates may come together to create one larger molecule. Two reactants might also enter a reaction, both become modified, and leave the reaction as two products. The location within the enzyme where the substrate binds is called the enzyme’s active site . The active site is where the “action” happens, so to speak. Since enzymes are proteins, there is a unique combination of amino acid residues (also called side chains, or R groups) within the active site. Each residue is characterized by different properties. Residues can be large or small, weakly acidic or basic, hydrophilic or hydrophobic, positively or negatively charged, or neutral. The unique combination of amino acid residues, their positions, sequences, structures, and properties, creates a very specific chemical environment within the active site. This specific environment is suited to bind, albeit briefly, to a specific chemical substrate (or substrates). Due to this jigsaw puzzle-like match between an enzyme and its substrates (which adapts to find the best fit between the transition state and the active site), enzymes are known for their specificity. The “best fit” results from the shape and the amino acid functional group’s attraction to the substrate. There is a specifically matched enzyme for each substrate and, thus, for each chemical reaction; however, there is flexibility as well. The fact that active sites are so perfectly suited to provide specific environmental conditions also means that they are subject to influences by the local environment. It is true that increasing the environmental temperature generally increases reaction rates, enzyme-catalyzed or otherwise. However, increasing or decreasing the temperature outside of an optimal range can affect chemical bonds within the active site in such a way that they are less well suited to bind substrates. High temperatures will eventually cause enzymes, like other biological molecules, to denature , a process that changes the natural properties of a substance. Likewise, the pH of the local environment can also affect enzyme function. Active site amino acid residues have their own acidic or basic properties that are optimal for catalysis. These residues are sensitive to changes in pH that can impair the way substrate molecules bind. Enzymes are suited to function best within a certain pH range, and, as with temperature, extreme pH values (acidic or basic) of the environment can cause enzymes to denature. Induced Fit and Enzyme Function For many years, scientists thought that enzyme-substrate binding took place in a simple “lock-and-key” fashion. This model asserted that the enzyme and substrate fit together perfectly in one instantaneous step. However, current research supports a more refined view called induced fit ( Figure 6.16 ). The induced-fit model expands upon the lock-and-key model by describing a more dynamic interaction between enzyme and substrate. As the enzyme and substrate come together, their interaction causes a mild shift in the enzyme’s structure that confirms an ideal binding arrangement between the enzyme and the transition state of the substrate. This ideal binding maximizes the enzyme’s ability to catalyze its reaction. Link to Learning View an animation of induced fit at this website . When an enzyme binds its substrate, an enzyme-substrate complex is formed. This complex lowers the activation energy of the reaction and promotes its rapid progression in one of many ways. On a basic level, enzymes promote chemical reactions that involve more than one substrate by bringing the substrates together in an optimal orientation. The appropriate region (atoms and bonds) of one molecule is juxtaposed to the appropriate region of the other molecule with which it must react. Another way in which enzymes promote the reaction of their substrates is by creating an optimal environment within the active site for the reaction to occur. Certain chemical reactions might proceed best in a slightly acidic or non-polar environment. The chemical properties that emerge from the particular arrangement of amino acid residues within an active site create the perfect environment for an enzyme’s specific substrates to react. You’ve learned that the activation energy required for many reactions includes the energy involved in manipulating or slightly contorting chemical bonds so that they can easily break and allow others to reform. Enzymatic action can aid this process. The enzyme-substrate complex can lower the activation energy by contorting substrate molecules in such a way as to facilitate bond-breaking, helping to reach the transition state. Finally, enzymes can also lower activation energies by taking part in the chemical reaction itself. The amino acid residues can provide certain ions or chemical groups that actually form covalent bonds with substrate molecules as a necessary step of the reaction process. In these cases, it is important to remember that the enzyme will always return to its original state at the completion of the reaction. One of the hallmark properties of enzymes is that they remain ultimately unchanged by the reactions they catalyze. After an enzyme is done catalyzing a reaction, it releases its product(s). Control of Metabolism Through Enzyme Regulation It would seem ideal to have a scenario in which all of the enzymes encoded in an organism’s genome existed in abundant supply and functioned optimally under all cellular conditions, in all cells, at all times. In reality, this is far from the case. A variety of mechanisms ensure that this does not happen. Cellular needs and conditions vary from cell to cell, and change within individual cells over time. The required enzymes and energetic demands of stomach cells are different from those of fat storage cells, skin cells, blood cells, and nerve cells. Furthermore, a digestive cell works much harder to process and break down nutrients during the time that closely follows a meal compared with many hours after a meal. As these cellular demands and conditions vary, so do the amounts and functionality of different enzymes. Since the rates of biochemical reactions are controlled by activation energy, and enzymes lower and determine activation energies for chemical reactions, the relative amounts and functioning of the variety of enzymes within a cell ultimately determine which reactions will proceed and at which rates. This determination is tightly controlled. In certain cellular environments, enzyme activity is partly controlled by environmental factors, like pH and temperature. There are other mechanisms through which cells control the activity of enzymes and determine the rates at which various biochemical reactions will occur. Regulation of Enzymes by Molecules Enzymes can be regulated in ways that either promote or reduce their activity. There are many different kinds of molecules that inhibit or promote enzyme function, and various mechanisms exist for doing so. In some cases of enzyme inhibition, for example, an inhibitor molecule is similar enough to a substrate that it can bind to the active site and simply block the substrate from binding. When this happens, the enzyme is inhibited through competitive inhibition , because an inhibitor molecule competes with the substrate for active site binding ( Figure 6.17 ). On the other hand, in noncompetitive inhibition, an inhibitor molecule binds to the enzyme in a location other than an allosteric site and still manages to block substrate binding to the active site. Some inhibitor molecules bind to enzymes in a location where their binding induces a conformational change that reduces the affinity of the enzyme for its substrate. This type of inhibition is called allosteric inhibition ( Figure 6.18 ). Most allosterically regulated enzymes are made up of more than one polypeptide, meaning that they have more than one protein subunit. When an allosteric inhibitor binds to an enzyme, all active sites on the protein subunits are changed slightly such that they bind their substrates with less efficiency. There are allosteric activators as well as inhibitors. Allosteric activators bind to locations on an enzyme away from the active site, inducing a conformational change that increases the affinity of the enzyme’s active site(s) for its substrate(s). Everyday Connection Drug Discovery by Looking for Inhibitors of Key Enzymes in Specific Pathways Enzymes are key components of metabolic pathways. Understanding how enzymes work and how they can be regulated is a key principle behind the development of many of the pharmaceutical drugs ( Figure 6.19 ) on the market today. Biologists working in this field collaborate with other scientists, usually chemists, to design drugs. Consider statins for example—which is the name given to the class of drugs that reduces cholesterol levels. These compounds are essentially inhibitors of the enzyme HMG-CoA reductase. HMG-CoA reductase is the enzyme that synthesizes cholesterol from lipids in the body. By inhibiting this enzyme, the levels of cholesterol synthesized in the body can be reduced. Similarly, acetaminophen, popularly marketed under the brand name Tylenol, is an inhibitor of the enzyme cyclooxygenase. While it is effective in providing relief from fever and inflammation (pain), its mechanism of action is still not completely understood. How are drugs developed? One of the first challenges in drug development is identifying the specific molecule that the drug is intended to target. In the case of statins, HMG-CoA reductase is the drug target. Drug targets are identified through painstaking research in the laboratory. Identifying the target alone is not sufficient; scientists also need to know how the target acts inside the cell and which reactions go awry in the case of disease. Once the target and the pathway are identified, then the actual process of drug design begins. During this stage, chemists and biologists work together to design and synthesize molecules that can either block or activate a particular reaction. However, this is only the beginning: both if and when a drug prototype is successful in performing its function, then it must undergo many tests from in vitro experiments to clinical trials before it can get FDA approval to be on the market. Many enzymes don’t work optimally, or even at all, unless bound to other specific non-protein helper molecules, either temporarily through ionic or hydrogen bonds or permanently through stronger covalent bonds. Two types of helper molecules are cofactors and coenzymes . Binding to these molecules promotes optimal conformation and function for their respective enzymes. Cofactors are inorganic ions such as iron (Fe++) and magnesium (Mg++). One example of an enzyme that requires a metal ion as a cofactor is the enzyme that builds DNA molecules, DNA polymerase, which requires bound zinc ion (Zn++) to function. Coenzymes are organic helper molecules, with a basic atomic structure made up of carbon and hydrogen, which are required for enzyme action. The most common sources of coenzymes are dietary vitamins ( Figure 6.20 ). Some vitamins are precursors to coenzymes and others act directly as coenzymes. Vitamin C is a coenzyme for multiple enzymes that take part in building the important connective tissue component, collagen. An important step in the breakdown of glucose to yield energy is catalysis by a multi-enzyme complex called pyruvate dehydrogenase. Pyruvate dehydrogenase is a complex of several enzymes that actually requires one cofactor (a magnesium ion) and five different organic coenzymes to catalyze its specific chemical reaction. Therefore, enzyme function is, in part, regulated by an abundance of various cofactors and coenzymes, which are supplied primarily by the diets of most organisms. Enzyme Compartmentalization In eukaryotic cells, molecules such as enzymes are usually compartmentalized into different organelles. This allows for yet another level of regulation of enzyme activity. Enzymes required only for certain cellular processes can be housed separately along with their substrates, allowing for more efficient chemical reactions. Examples of this sort of enzyme regulation based on location and proximity include the enzymes involved in the latter stages of cellular respiration, which take place exclusively in the mitochondria, and the enzymes involved in the digestion of cellular debris and foreign materials, located within lysosomes. Feedback Inhibition in Metabolic Pathways Molecules can regulate enzyme function in many ways. A major question remains, however: What are these molecules and where do they come from? Some are cofactors and coenzymes, ions, and organic molecules, as you’ve learned. What other molecules in the cell provide enzymatic regulation, such as allosteric modulation, and competitive and noncompetitive inhibition? The answer is that a wide variety of molecules can perform these roles. Some of these molecules include pharmaceutical and non-pharmaceutical drugs, toxins, and poisons from the environment. Perhaps the most relevant sources of enzyme regulatory molecules, with respect to cellular metabolism, are the products of the cellular metabolic reactions themselves. In a most efficient and elegant way, cells have evolved to use the products of their own reactions for feedback inhibition of enzyme activity. Feedback inhibition involves the use of a reaction product to regulate its own further production ( Figure 6.21 ). The cell responds to the abundance of specific products by slowing down production during anabolic or catabolic reactions. Such reaction products may inhibit the enzymes that catalyzed their production through the mechanisms described above. The production of both amino acids and nucleotides is controlled through feedback inhibition. Additionally, ATP is an allosteric regulator of some of the enzymes involved in the catabolic breakdown of sugar, the process that produces ATP. In this way, when ATP is abundant, the cell can prevent its further production. Remember that ATP is an unstable molecule that can spontaneously dissociate into ADP. If too much ATP were present in a cell, much of it would go to waste. On the other hand, ADP serves as a positive allosteric regulator (an allosteric activator) for some of the same enzymes that are inhibited by ATP. Thus, when relative levels of ADP are high compared to ATP, the cell is triggered to produce more ATP through the catabolism of sugar.
american_government
Summary 14.1 State Power and Delegation The power structure of government established in the Articles of Confederation was rebalanced in the Constitution to ensure that both the central and the regional governments had some degree of authority and autonomy. Federal and state governments have managed to work out sharing power throughout history, with the federal government often using fiscal policy to encourage compliance from the states. The taxing power of local governments means they face unique pressures during economic downturns. 14.2 State Political Culture Daniel Elazar’s theory argues, based on the cultural values of early immigrants who settled in different regions of the country, the United States is made up of three component cultures: individualistic, moralistic, and traditionalistic. Each culture views aspects of government and politics differently, particularly the nature and purpose of political competition and the role of citizen participation. Critics of the theory say the arrival of recent immigrants from other parts of the globe, the divide between urban and rural lifestyles in a particular state, and new patterns of diffusion and settlement across states and regions mean the theory is no longer an entirely accurate description of reality. 14.3 Governors and State Legislatures Governors are called upon to work with the state legislature in the lawmaking process, to be the head of their political party, and to be the chief spokespersons and crisis managers for their states. State constitution or state statutes give many governors the power to veto legislation, pardon or commute the sentences of convicted criminals, author a state budget, and call a special session of the state legislature. The three key functions performed by state legislatures are lawmaking, constituency service, and oversight. Legislatures differ in size, diversity, party composition, and level of professionalism across the fifty states. 14.4 State Legislative Term Limits Whether they cap lifetime service or consecutive terms, term limits have become popular in many states, though some have overturned them as unconstitutional. Proponents believe term limits increase voter participation, encourage more women and minorities to run for office, and help bring diversity and fresh ideas to the legislature. Opponents point to research showing that diversity has not increased in term-limit states, and that younger and less experienced legislators tend to rely more on lobbyists for information about proposed bills. Finally, voters disappointed at losing their favorites may fail to go to the polls. 14.5 County and City Government County governments can adopt the commission system, the council-administrator system, and the council-elected executive system of government to carry out their functions, which usually include the work of the sheriff, the county clerk, the assessor, the treasurer, the coroner, and the engineer. Municipal governments can use the mayor-council system or the council-manager system and manage services such as the provision of clean water, park maintenance, and local law enforcement. Cities and counties both rely on tax revenues, especially property taxes, to fund their provision of services.
Chapter Outline 14.1 State Power and Delegation 14.2 State Political Culture 14.3 Governors and State Legislatures 14.4 State Legislative Term Limits 14.5 County and City Government Introduction Controversial national policy decisions by lawmakers and justices tend to grab headlines and dominate social media, while state and local government matters often evoke less enthusiasm. Yet, if we think about which level of government most directly affects us on a daily basis, it is undoubtedly the level closest to us, including our city, county, school districts, and state government. Whether it is by maintaining roads we drive on each day, supplying clean water with which we brush our teeth, or allocating financial support to higher education, state and local government provides resources that shape our everyday lives, including your final tuition bill ( Figure 14.1 ). How do state and local governments gain the authority to make these decisions, and how are their actions guided by cultural and other differences between the states? What tensions exist between national and state governments on policy matters, and what unique powers do mayors and governors enjoy? By answering these and other questions, this chapter explores the role of state and local governments in our lives.
[ { "answer": { "ans_choice": 0, "ans_text": "A" }, "bloom": null, "hl_context": "Growing financial resources gave the federal government increased power over subnational governments . <hl> This increased power was because it could use categorical grants to dictate the terms and conditions state governments had to meet to qualify for financial assistance in a specific policy area . <hl> Over time , the federal government even began to require state and local governments to comply with legislative and executive authorizations when funding was not attached . These requests from the federal government are referred to as unfunded mandates and are a source of dissatisfaction to political actors at the state and local level . To provide more transparency to state and local governments and reduce the federal government ’ s use of mandates , the Unfunded Mandates Reform Act was passed in 1995 . This act requires the Congressional Budget Office to provide information about the cost of any proposed government mandate that exceeds a specified threshold before the bill can be considered in Congress . 8", "hl_sentences": "This increased power was because it could use categorical grants to dictate the terms and conditions state governments had to meet to qualify for financial assistance in a specific policy area .", "question": { "cloze_format": "________ dictate the terms and conditions state governments would have to meet in order to qualify for financial assistance in a specific policy area.", "normal_format": "Which dictate the terms and conditions state governments would have to meet in order to qualify for financial assistance in a specific policy area?", "question_choices": [ "Categorical grants", "Block grants", "Unfunded mandates", "Crossover sanctions" ], "question_id": "fs-id1163757214681", "question_text": "________ dictate the terms and conditions state governments would have to meet in order to qualify for financial assistance in a specific policy area." }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 2, "ans_text": "reserved powers" }, "bloom": null, "hl_context": "Despite the Constitution ’ s broad grants of state authority , one of the central goals of the Anti-Federalists , a group opposed to several components of the Constitution , was to preserve state government authority , protect the small states , and keep government power concentrated in the hands of the people . <hl> For this reason , the Tenth Amendment was included in the Bill of Rights to create a class of powers , known as reserved powers , exclusive to state governments . <hl> The amendment specifically reads , “ The powers not delegated to the United States by the Constitution , nor prohibited by it to the States , are reserved to the States respectively , or to the people . ” In essence , if the Constitution does not decree that an activity should be performed by the national government and does not restrict the state government from engaging in it , then the state is seen as having the power to perform the function . In other words , the power is reserved to the states .", "hl_sentences": "For this reason , the Tenth Amendment was included in the Bill of Rights to create a class of powers , known as reserved powers , exclusive to state governments .", "question": { "cloze_format": "The Tenth Amendment created a class of powers exclusive to state governments. These powers are referred to as ________.", "normal_format": "The Tenth Amendment created a class of powers exclusive to state governments. How are these powers referred to as?", "question_choices": [ "enumerated powers", "implied powers", "reserved powers", "none of the above" ], "question_id": "fs-id1163757303620", "question_text": "The Tenth Amendment created a class of powers exclusive to state governments. These powers are referred to as ________." }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 2, "ans_text": "C" }, "bloom": null, "hl_context": "<hl> Given the prominence of slavery in its formation , a traditionalistic political culture , in Elazar ’ s argument , sees the government as necessary to maintaining the existing social order , the status quo . <hl> Only elites belong in the political enterprise , and as a result , new public policies will be advanced only if they reinforce the beliefs and interests of those in power .", "hl_sentences": "Given the prominence of slavery in its formation , a traditionalistic political culture , in Elazar ’ s argument , sees the government as necessary to maintaining the existing social order , the status quo .", "question": { "cloze_format": "In a ________ political culture, the government is seen as a mechanism for maintaining the existing social order or status quo.", "normal_format": "In which political culture, is the government seen as a mechanism for maintaining the existing social order or status quo?", "question_choices": [ "moralistic", "individualistic", "traditionalistic", "nativistic" ], "question_id": "fs-id1163758447917", "question_text": "In a ________ political culture, the government is seen as a mechanism for maintaining the existing social order or status quo." }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 1, "ans_text": "B" }, "bloom": null, "hl_context": "<hl> Milestone Oregon ’ s Efforts to Expand the Voting Franchise In 1998 , Oregon became the first state to switch to mail-in voting when citizens passed a ballot measure for it to take effect . <hl> In March 2015 , Governor Kate Brown took another step to expand the voting franchise . She signed a bill into law that makes voter registration automatic for all citizens in the state with a driver ’ s license . These citizens will now be automatically registered to vote in elections and will receive a mail-in ballot before Election Day unless they specifically opt out with the Oregon secretary of state ’ s office .", "hl_sentences": "Milestone Oregon ’ s Efforts to Expand the Voting Franchise In 1998 , Oregon became the first state to switch to mail-in voting when citizens passed a ballot measure for it to take effect .", "question": { "cloze_format": "________ was the first state to institute all mail-in voting and automatic voter registration.", "normal_format": "Which state was the first to institute all mail-in voting and automatic voter registration?", "question_choices": [ "California", "Oregon", "Washington", "New York" ], "question_id": "fs-id1163758519668", "question_text": "________ was the first state to institute all mail-in voting and automatic voter registration." }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 0, "ans_text": "delegate" }, "bloom": null, "hl_context": "Besides generating public policy , state legislatures try to represent the interests of their constituents . Edmund Burke was a political philosopher who theorized that representatives are either delegates or trustees . <hl> 53 A delegate legislator represents the will of those who elected him or her to office and acts in their expressed interest , even when it goes against personal belief about what is ultimately in the constituency ’ s best interest . <hl> On the other hand , trustee s believe they were elected to exercise their own judgment and know best because they have the time and expertise to study and understand an issue . Thus , a trustee will be willing to vote against the desire of the constituency so long as he or she believes it is in the people ’ s best interest . A trustee will also be more likely to vote his or her conscience on issues that are personal to him or her , such as on same-sex marriage or abortion rights .", "hl_sentences": "53 A delegate legislator represents the will of those who elected him or her to office and acts in their expressed interest , even when it goes against personal belief about what is ultimately in the constituency ’ s best interest .", "question": { "cloze_format": "A ________ is an officeholder who represents the will of those who elected him or her and acts in constituents’ expressed interest.", "normal_format": "Which is an officeholder who represents the will of those who elected him or her and acts in constituents’ expressed interest?", "question_choices": [ "delegate", "trustee", "politico", "citizen" ], "question_id": "fs-id1163757186701", "question_text": "A ________ is an officeholder who represents the will of those who elected him or her and acts in constituents’ expressed interest." }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 1, "ans_text": "B" }, "bloom": null, "hl_context": "As a whole , state legislatures have become progressively more professional . Political scientist Peverill Squire , at several points throughout his career , has measured the degree of state legislative professionalism with a ranking across the fifty states . 61 Legislative professionalism is assessed according to three key factors : state legislators ’ salary , the length of time they are in session , and the number of staff at their disposal . Members of professional or full-time legislatures tend to consider legislative service their full-time occupation , and they are paid enough not to require a second occupation . They also have larger staffs to assist with their work , and they tend to be in session for much of the year . <hl> On the other end of the spectrum are citizen , or part-time , legislatures . <hl> Representatives and senators in these legislatures do not enjoy the same perks as their counterparts in professional legislatures . <hl> Generally , salary is much lower and so is staff assistance . <hl> <hl> Members typically need to seek outside employment to supplement their income from legislative work , and the legislature will meet for only a brief period of time during the year . <hl>", "hl_sentences": "On the other end of the spectrum are citizen , or part-time , legislatures . Generally , salary is much lower and so is staff assistance . Members typically need to seek outside employment to supplement their income from legislative work , and the legislature will meet for only a brief period of time during the year .", "question": { "cloze_format": "In a ________ legislature, members tend to have low salaries, shorter sessions, and few staff members to assist them with their legislative functions.", "normal_format": "In which legislature members tend to have low salaries, shorter sessions, and few staff members to assist them with their legislative functions?", "question_choices": [ "professional", "citizen", "hybrid", "unicameral" ], "question_id": "fs-id1163755042141", "question_text": "In a ________ legislature, members tend to have low salaries, shorter sessions, and few staff members to assist them with their legislative functions." }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 2, "ans_text": "reduction" }, "bloom": null, "hl_context": "The ability to veto legislation is just one of the formal powers governors have at their disposal . Formal powers are powers the governor may exercise that are specifically outlined in state constitutions or state law . 30 Unlike U . S . presidents , many governors also have additional veto powers at their disposal , which enhances their ability to check the actions of the legislative branch . For instance , most states provide governors the power of the line-item veto . The line-item veto gives governors the ability to strike out a line or individual portions of a bill while letting the remainder pass into law . In addition , approximately 30 percent of governors have the power of an amendatory veto , which allows them to send a bill back to the legislature and request a specific amendment to it . <hl> Finally , a small number of governors , including the governor of Texas , also have the power of a reduction veto , which allows them to reduce the budget proposed in a piece of legislation . <hl> 31", "hl_sentences": "Finally , a small number of governors , including the governor of Texas , also have the power of a reduction veto , which allows them to reduce the budget proposed in a piece of legislation .", "question": { "cloze_format": "A(n) ________ veto allows the governor to cross out budget lines in the legislature-approved budget, while signing the remainder of the budget into law.", "normal_format": "Which veto allows the governor to cross out budget lines in the legislature-approved budget, while signing the remainder of the budget into law?", "question_choices": [ "amendatory", "line-item", "reduction", "Frankenstein" ], "question_id": "fs-id1163757233769", "question_text": "A(n) ________ veto allows the governor to cross out budget lines in the legislature-approved budget, while signing the remainder of the budget into law." }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 1, "ans_text": "False" }, "bloom": null, "hl_context": "<hl> Under consecutive term limits , a member can serve for only a specified period of time in either the state house or the state senate , most commonly eight years . <hl> <hl> To try to regain a seat in the legislature once the limit has been met , the member will have to wait to run for office again . <hl> <hl> If the member succeeds , the clock will reset and the legislator may once again serve up to the limit set by the state . <hl> In states with a lifetime ban , such as Oklahoma , members can serve only one time for the number of years allotted , and they are not permitted to run for office again ( Figure 14.16 ) . 65", "hl_sentences": "Under consecutive term limits , a member can serve for only a specified period of time in either the state house or the state senate , most commonly eight years . To try to regain a seat in the legislature once the limit has been met , the member will have to wait to run for office again . If the member succeeds , the clock will reset and the legislator may once again serve up to the limit set by the state .", "question": { "cloze_format": "It is ___ that under consecutive term limits, legislators can serve one time for the number of years allotted and are not permitted to ever compete for the office again.", "normal_format": "Under consecutive term limits, legislators can serve one time for the number of years allotted and are not permitted to ever compete for the office again.", "question_choices": [ "True", "False" ], "question_id": "fs-id1163757613399", "question_text": "Under consecutive term limits, legislators can serve one time for the number of years allotted and are not permitted to ever compete for the office again." }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 2, "ans_text": "C" }, "bloom": null, "hl_context": "<hl> Under consecutive term limits , a member can serve for only a specified period of time in either the state house or the state senate , most commonly eight years . <hl> To try to regain a seat in the legislature once the limit has been met , the member will have to wait to run for office again . If the member succeeds , the clock will reset and the legislator may once again serve up to the limit set by the state . In states with a lifetime ban , such as Oklahoma , members can serve only one time for the number of years allotted , and they are not permitted to run for office again ( Figure 14.16 ) . 65 <hl> Term limits restrict the length of time a member can serve in the state legislature by capping either lifetime service or the number of consecutive terms . <hl> The term limits movement gained momentum in the 1990s , spreading across a wide array of state legislative institutions . <hl> Today , fifteen states have imposed term limits on their state house and state senate members . <hl> On the other hand , six states , one as recently as 2004 , have repealed the term limits imposed on them by the electorate , through either judicial action in the state Supreme Courts or through legislative action in the state legislature . 64", "hl_sentences": "Under consecutive term limits , a member can serve for only a specified period of time in either the state house or the state senate , most commonly eight years . Term limits restrict the length of time a member can serve in the state legislature by capping either lifetime service or the number of consecutive terms . Today , fifteen states have imposed term limits on their state house and state senate members .", "question": { "cloze_format": "The most common term limit across the states that have imposed them is ________ years.", "normal_format": "How many years is the most common term limit across the states that have imposed them?", "question_choices": [ "four", "six", "eight", "twelve" ], "question_id": "fs-id1163757470128", "question_text": "The most common term limit across the states that have imposed them is ________ years." }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 1, "ans_text": "a decision by the state Supreme Court" }, "bloom": null, "hl_context": "The first term limits were enacted in 1990 in California , Colorado , and Oklahoma . In 1992 , eight more states followed suit in one large wave . The last state to enact term limits on legislative members was Nebraska in 2000 . <hl> 66 However , term limits did not stay in effect in all these states ; many state supreme courts repealed them and declared them unconstitutional for a variety of reasons ( Figure 14.17 ) . <hl> For instance , in Massachusetts and Washington , term limits were deemed unconstitutional because they affected candidate qualifications to compete for a given office . The courts ruled that changes to those qualifications could be made only by amending the state constitution , not by voters changing the state law . 67", "hl_sentences": "66 However , term limits did not stay in effect in all these states ; many state supreme courts repealed them and declared them unconstitutional for a variety of reasons ( Figure 14.17 ) .", "question": { "cloze_format": "When term limits have been overturned, the most common method was ________.", "normal_format": "When term limits have been overturned, what was the most common method?", "question_choices": [ "a bill passed by the state legislature", "a decision by the state Supreme Court", "a voter referendum", "a governor’s decree" ], "question_id": "fs-id1163757378681", "question_text": "When term limits have been overturned, the most common method was ________." }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 1, "ans_text": "B" }, "bloom": null, "hl_context": "Although proponents argued that term limits would increase legislative diversity , research comparing the rate of female and minority representation in term-limited and non-term-limited states does not bear out this expectation . There is no statistically significant difference in diversity between the two groups of states . <hl> 72 Although term limits may have produced more open seats , additional barriers to holding office can still exist and affect the willingness of women and minorities to run for office . <hl> <hl> In addition , women and minorities are subject to the same term limits as men , and given their low numbers among candidates for office , on balance a legislature can lose more women or minorities than it gains . <hl>", "hl_sentences": "72 Although term limits may have produced more open seats , additional barriers to holding office can still exist and affect the willingness of women and minorities to run for office . In addition , women and minorities are subject to the same term limits as men , and given their low numbers among candidates for office , on balance a legislature can lose more women or minorities than it gains .", "question": { "cloze_format": "It is ___ that term limits have produced a statistically significant increase in the number of women serving in state legislatures.", "normal_format": "Term limits have produced a statistically significant increase in the number of women serving in state legislatures.", "question_choices": [ "True", "False" ], "question_id": "fs-id1163757211603", "question_text": "Term limits have produced a statistically significant increase in the number of women serving in state legislatures." }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 2, "ans_text": "fifteen" }, "bloom": null, "hl_context": "Term limits restrict the length of time a member can serve in the state legislature by capping either lifetime service or the number of consecutive terms . The term limits movement gained momentum in the 1990s , spreading across a wide array of state legislative institutions . <hl> Today , fifteen states have imposed term limits on their state house and state senate members . <hl> On the other hand , six states , one as recently as 2004 , have repealed the term limits imposed on them by the electorate , through either judicial action in the state Supreme Courts or through legislative action in the state legislature . 64", "hl_sentences": "Today , fifteen states have imposed term limits on their state house and state senate members .", "question": { "cloze_format": "Currently, ________ states have term limits in place.", "normal_format": "How many states have term limits in place currently?", "question_choices": [ "five", "ten", "fifteen", "twenty" ], "question_id": "fs-id1163757606939", "question_text": "Currently, ________ states have term limits in place." }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 0, "ans_text": "A" }, "bloom": null, "hl_context": "<hl> Under the mayor-council system voters elect both a mayor and members of the city council . <hl> <hl> The city council performs legislative functions and the mayor the executive functions . <hl> Under this system , the mayor may be given a great deal of authority or only limited powers . 82 Under a strong mayor system , the mayor will be able to veto the actions of the council , appoint and fire the heads of city departments , and produce a budget . Under a weak mayor system , the mayor has little authority compared to the council and acts in a ceremonial capacity as a spokesperson for the city . 83", "hl_sentences": "Under the mayor-council system voters elect both a mayor and members of the city council . The city council performs legislative functions and the mayor the executive functions .", "question": { "cloze_format": "Under the mayor-council system, the ________.", "normal_format": "Under the mayor-council system, which of the following occurs?", "question_choices": [ "legislative and executive responsibilities are separated", "political and administrative functions are separated", "mayor chairs the city council", "city council selects the mayor" ], "question_id": "fs-id1163755267563", "question_text": "Under the mayor-council system, the ________." }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 2, "ans_text": "the mayor-council system" }, "bloom": null, "hl_context": "County governments serve a larger geographical area than cities and towns , but a smaller area than states . They are created by the state government and typically operate under provisions set out in the state constitution . As such , they are essentially administrative units of the state . Census estimates from 2012 indicate that there are just over three thousand counties in the United States . <hl> 75 County systems usually take one of three basic forms : the commission system , the council-administrator system , and the council-elected executive system . <hl>", "hl_sentences": "75 County systems usually take one of three basic forms : the commission system , the council-administrator system , and the council-elected executive system .", "question": { "cloze_format": "___ is not one of the three forms of county government.", "normal_format": "Which of the following is not one of the three forms of county government?", "question_choices": [ "the commission system", "the council-elected executive system", "the mayor-council system", "the council-administrator system" ], "question_id": "fs-id1163755031522", "question_text": "Which of the following is not one of the three forms of county government?" }, "references_are_paraphrase": null } ]
14
14.1 State Power and Delegation Learning Objectives By the end of this section, you will be able to: Explain how the balance of power between national and state governments shifted with the drafting and ratification of the Constitution Identify parts of the Constitution that grant power to the national government and parts that support states’ rights Identify two fiscal policies by which the federal government exerts control over state policy decisions When the framers met at the Constitutional Convention in 1787, they had many competing tensions to resolve. For instance, they had to consider how citizens would be represented in the national government, given population differences between the states. In addition, they had to iron out differences of opinion about where to concentrate political power. Would the legislative branch have more authority than the executive branch, and would state governments retain as many rights as they had enjoyed under the Articles of Confederation? Here we look at the manner in which power was divided between the national and state governments, first under the Articles of Confederation and then under the U.S. Constitution. As you read, observe the shifting power dynamic between the national government and subnational governments at the state and local level. STATE POWER AT THE FOUNDING Before the ratification of the Constitution, the state governments’ power far exceeded that held by the national government. This distribution of authority was the result of a conscious decision and was reflected in the structure and framework of the Articles of Confederation . The national government was limited, lacking both a president to oversee domestic and foreign policy and a system of federal courts to settle disputes between the states. Restricting power at the national level gave the states a great deal of authority over and independence from the federal government. Each state legislature appointed its own Congressional representatives, subject to recall by the states, and each state was given the authority to collect taxes from its citizens. But limiting national government power was not the delegates’ only priority. They also wanted to prevent any given state from exceeding the authority and independence of the others. The delegates ultimately worked to create a level playing field between the individual states that formed the confederation. For instance, the Articles of Confederation could not be amended without the approval of each state, and each state received one vote in Congress, regardless of population. 1 It wasn’t long after the Articles of Confederation were established that cracks began to appear in their foundation. Congress struggled to conduct business and to ensure the financial credibility of the new country’s government. One difficulty was its inability to compel the individual states to cover their portion of Revolutionary War debt. Attempts to recoup these funds through the imposition of tariffs were vetoed by states with a vested financial interest in their failure. 2 Given the inherent weaknesses in the system set up by the Articles, in 1787 the delegates came together once again to consider amendments to the Articles, but they ended up instead considering a new design for the government ( Figure 14.2 ). To produce more long-term stability, they needed to establish a more effective division of power between the federal and state governments. Ultimately, the framers settled on a system in which power would be shared: The national government had its core duties, the state governments had their duties, and other duties were shared equally between them. Today this structure of power sharing is referred to as federalism . The Constitution allocated more power to the federal government by effectively adding two new branches: a president to head the executive branch and the Supreme Court to head the judicial branch. The specific delegated or expressed powers granted to Congress and to the president were clearly spelled out in the body of the Constitution under Article I, Section 8, and Article II , Sections 2 and 3. In addition to these expressed powers, the national government was given implied powers that, while not clearly stated, are inferred. These powers stem from the elastic clause in Article I , Section 8, of the Constitution, which provides Congress the authority “to make all Laws which shall be necessary and proper for carrying into Execution the Foregoing powers.” This statement has been used to support the federal government’s playing a role in controversial policy matters, such as the provision of healthcare, the expansion of power to levy and collect taxes, and regulation of interstate commerce. Finally, Article VI declared that the U.S. Constitution and any laws or treaties made in connection with that document were to supersede constitutions and laws made at the state level. This clause, better known as the supremacy clause , makes clear that any conflict in law between the central (or federal) government and the regional (or state) governments is typically resolved in favor of the central government. Although the U.S. Constitution clearly allocated more power to the federal government than had been the case under the Articles of Confederation, the framers still respected the important role of the states in the new government. The states were given a host of powers independent of those enjoyed by the national government. As one example, they now had the power to establish local governments and to account for the structure, function, and responsibilities of these governments within their state constitutions. This gave states sovereignty, or supreme and independent authority, over county, municipal, school and other special districts. States were also given the power to ratify amendments to the U.S. Constitution. Throughout U.S. history, all amendments to the Constitution except one have been proposed by Congress and then ratified by either three-fourths of the state legislatures or three-fourths of the state conventions called for ratification purposes. This process ensures that the states have a voice in any changes to the Constitution. The Twenty-First Amendment (repealing the Eighteenth Amendment’s prohibition on alcohol) was the only amendment ratified using the state ratifying convention method. Although this path has never been taken, the U.S. Constitution even allows for state legislatures to take a direct and very active role in the amendment proposal process. If at least two-thirds of the state legislatures apply for a national convention, constitutional amendments can be proposed at the convention. Finding a Middle Ground Debating the Need for a National Convention As of 2015, twenty-seven states had passed applications to hold a national convention. These states are pushing for the opportunity to propose a constitutional amendment requiring the national government to balance its budget in the same way most states are mandated to do. For a national convention to be held, at least thirty-four states must submit applications. Thus, only seven states currently stand in the way of the first national convention in U.S. history. 3 Proponents see the convention as an opportunity to propose an amendment they argue is necessary to reduce federal spending and promote fiscal responsibility. Conservatives and Tea Party members believe reducing the deficit is important to maintaining the country’s future economic health and its competitive strength in global markets. They also believe the growing roster of states favoring a convention may encourage Congress to take action on its own. Opponents feel a balanced budget amendment is not realistic given the need for emergency spending in the event of an economic recession. They also worry about the spending cuts and/or tax increases the federal government would have to impose to consistently balance the budget. Some states fear a balanced-budget requirement would limit the federal government’s ability to provide them with continued fiscal support. Finally, other opponents argue that states balance only their operating budgets, while themselves assuming massive amounts of debt for capital projects. But perhaps the greatest fear is of the unknown. A national convention is unprecedented, and there is no limit to the number of amendments delegates to such a convention might propose. However, such changes would still need to be ratified by three-fourths of the state legislatures or state conventions before they could take effect. What are the potential benefits of a national constitutional convention? What are the risks? Are the benefits worth the risks? Why or why not? Despite the Constitution’s broad grants of state authority, one of the central goals of the Anti-Federalists, a group opposed to several components of the Constitution, was to preserve state government authority, protect the small states, and keep government power concentrated in the hands of the people. For this reason, the Tenth Amendment was included in the Bill of Rights to create a class of powers, known as reserved powers, exclusive to state governments. The amendment specifically reads, “The powers not delegated to the United States by the Constitution, nor prohibited by it to the States, are reserved to the States respectively, or to the people.” In essence, if the Constitution does not decree that an activity should be performed by the national government and does not restrict the state government from engaging in it, then the state is seen as having the power to perform the function. In other words, the power is reserved to the states. Besides reserved powers, the states also retained concurrent powers, or responsibilities shared with the national government. As part of this package of powers, the state and federal governments each have the right to collect income tax from their citizens and corporate tax from businesses. They also share responsibility for building and maintaining the network of interstates and highways and for making and enforcing laws ( Figure 14.3 ). For instance, many state governments have laws regulating motorcycle and bicycle helmet use, banning texting and driving, and prohibiting driving under the influence of drugs or alcohol. THE EVOLUTION OF STATE POWER Throughout U.S. history, the national and state governments have battled for dominance over the implementation of public policy and the funding of important political programs. Upon taking office in 1933 during the Great Depression (1929–1939), President Franklin D. Roosevelt initiated a series of legislative proposals to boost the economy and put people back to work. The enacted programs allowed the federal government to play a broader role in revitalizing the economy while greatly expanding its power. However, this result was not without its critics. Initially, the Supreme Court overturned several key legislative proposals passed under Roosevelt, reasoning that they represented an overreach of presidential authority and were unconstitutional, such as Schechter Poultry Corp. v. United States . 4 Eventually, however, the Supreme Court shifted direction to reflect public opinion, which was decisively behind the president and the need for government intervention in a time of economic turmoil. 5 Just three decades later, during the 1964 presidential election campaign, incumbent President Lyndon B. Johnson declared a “ War on Poverty ,” instituting a package of Great Society programs designed to improve circumstances for lower-income Americans across the nation. The new programs included Medicare and Medicaid , which are health insurance programs for seniors and low-income citizens respectively, and the food stamp program, which provides food assistance to low-income families. These initiatives greatly expanded the role of the federal government in providing a social safety net. 6 State and local governments became partners in their implementation and also came to rely on the financial support they received from the federal government in the form of program grants. 7 As the federal government’s role in policy creation expanded, so did its level of spending. Spending by the federal government began to surpass that of state and local governments shortly after 1940 ( Figure 14.4 ). It spiked temporarily during the Great Depression and again during World War II, resuming a slow climb with the implementation of Johnson’s Great Society programs noted above. Growing financial resources gave the federal government increased power over subnational governments. This increased power was because it could use categorical grants to dictate the terms and conditions state governments had to meet to qualify for financial assistance in a specific policy area. Over time, the federal government even began to require state and local governments to comply with legislative and executive authorizations when funding was not attached. These requests from the federal government are referred to as unfunded mandates and are a source of dissatisfaction to political actors at the state and local level. To provide more transparency to state and local governments and reduce the federal government’s use of mandates, the Unfunded Mandates Reform Act was passed in 1995. This act requires the Congressional Budget Office to provide information about the cost of any proposed government mandate that exceeds a specified threshold before the bill can be considered in Congress. 8 Link to Learning Explore the latest news on federal mandates at the Congressional Budget Office and the Catalog of Cost Shifts to States at the National Conference of State Legislatures website. Despite the national government’s power to pass and fund policy that affects lower-level governments, states still have gained considerable headway since the late twentieth century. For instance, with the passage of the Personal Responsibility and Work Opportunity Reconciliation Act in 1996, known as the welfare reform bill, states were given great discretion over the provision of welfare. The federal government reduced its level of monetary support for the program and, in exchange, the states gained more authority over its implementation. States were able to set more restrictive work requirements, to place caps on the number of family members who could receive aid, and to limit the length of time someone could qualify for government assistance. 9 Since then, states have been granted the flexibility to set policy across a number of controversial policy areas. For instance, a wide array of states require parental consent for abortions performed on minors, set waiting periods before an abortion can be performed, or require patients to undergo an ultrasound before the procedure. As another example, currently, almost half the states allow for the use of medical marijuana and three states have fully legalized it, despite the fact that this practice stands in contradiction to federal law that prohibits the use and distribution of marijuana. Link to Learning For more on these two controversial policy areas, explore ”An Overview of State Abortion Laws” and ”State Medical Marijuana Laws.” Today, it is not uncommon to see a patchwork of legal decisions granting states more discretion in some policy areas, such as marijuana use, while providing the federal government more authority in others, such as same-sex marriage. Decisions about which level controls policy can reflect the attitudes of government officials and the public, political ideology and the strategic advantage of setting policy on a state-by-state basis, and the necessity of setting uniform policy in the face of an economic downturn or unanticipated national security threat. What has not changed over time is the central role of the U.S. Supreme Court’s views in determining how power should be distributed in a federalist system. POWER AT THE SUBSTATE LEVEL The U.S. Constitution is silent on the dispersion of power between states and localities within each state. The fact that states are mentioned specifically and local jurisdictions are not has traditionally meant that power independent of the federal government resides first with the state. Through their own constitutions and statutes, states decide what to require of local jurisdictions and what to delegate. This structure represents the legal principle of Dillon’s Rule , named for Iowa Supreme Court justice John F. Dillon . Dillon argued that state actions trump those of the local government and have supremacy. 10 In this view, cities and towns exist at the pleasure of the state, which means the state can step in and dissolve them or even take them over. Indeed, most states have supremacy clauses over local governments in their constitutions. However, for practical purposes, state and local governments must work together to ensure that citizens receive adequate services. Given the necessity of cooperation, many states have granted local governments some degree of autonomy and given them discretion to make policy or tax decisions. 11 This added independence is called home rule , and the transfer of power is typically spelled out within a charter . Charters are similar to state constitutions: they provide a framework and a detailed accounting of local government responsibilities and areas of authority. Potential conflicts can come up over home rule. For example, in 2015, the State of Texas overruled a fracking ban imposed by the City of Denton. 12 Like state governments, local governments prioritize spending on building and maintaining the transportation infrastructure, supporting educational institutions, promoting community protection, and funding healthcare. 13 As shown in Figure 14.5 , local governments, just like state governments, receive a sizeable chunk of their revenue from grants and transfers from other levels of the government. The next biggest source of revenue for local governments is property tax collections. Property taxes can be assessed on homes, land, and businesses. The local government’s reliance on property tax revenue can be problematic for a number of reasons. First, unlike sales tax, the collection of which is spaced out in small increments across multiple transactions, property tax is collected in one or two lump sums and is therefore highly visible and unpopular. 14 In fact, in response to tax rate increases, many states have placed legal or constitutional limits on regional governments’ ability to raise property taxes. The trend began in California with the 1978 passage of Proposition 13 . This citizen-driven initiative capped the real estate tax at 1 percent of the cash value of property and stopped the practice of reassessing properties for tax purposes whenever a home in the neighborhood was sold. 15 After its passage, a number of other states followed suit, making it more difficult for states to reap the rewards of sharp increases in the market value of property. Another drawback to local governments’ reliance on property tax is that property values vary with the economic health of a given area, the quality of school districts, and the overall desirability of a state, municipality, or county. Significant parcels of land in many cities are also tax-exempt, including property occupied by colleges, churches, and other nonprofit organizations. Boston is a good example as almost 50 percent of the assessed value of property is tax-exempt. 16 College towns face the same challenge. When the mortgage crisis began in 2007, property values decreased in many areas of the country, and many homeowners defaulted on their mortgages because their homes were now worth less than they had borrowed to buy them. With the decline in property values, local governments faced a loss in tax revenue at the same time states were cutting back on aid; tax collections were also down because of economic conditions and the inability to derive income tax from internet sales. A number of municipalities filed for bankruptcy in the face of fiscal distress during the economic recession. Perhaps the best known municipality was Detroit, Michigan, which filed for Chapter 9 bankruptcy in 2013 ( Figure 14.6 ). Detroit filed for bankruptcy due to massive debt obligations and demands for repayment that it could not meet due to a perfect storm of economic and democratic factors. The city owed money to investors who had loaned it money, and it had liabilities resulting from its failure to fulfill its pension and healthcare obligations to city workers. The bankruptcy allowed the city time to develop an exit strategy and negotiate with creditors and union representatives in an effort to restructure its debt load. 17 Indeed, Detroit recently emerged from bankruptcy and has started to rebuild economically. Detroit’s fiscal condition only highlights the unique challenges municipalities face. Local governments have to provide many of the same services as state and national governments, but they are often constrained by the boundaries the state prescribes. They may not have the authority to raise revenue above a certain threshold, and they do not have the ability to pass expenses on to another level of government because they lack sovereignty. 14.2 State Political Culture Learning Objectives By the end of this section, you will be able to: Compare Daniel Elazar’s three forms of political culture Describe how cultural differences between the states can shape attitudes about the role of government and citizen participation Discuss the main criticisms of Daniel Elazar’s theory Some states, such as Alaska, are endowed with natural resources. They can use their oil or natural gas reserves to their advantage to fund education or reduce taxes. Other states, like Florida, are favored with a climate that attracts tourists and retirees each winter, drawing in revenues to support infrastructure improvements throughout the state. These differences can lead to strategic advantages in the economic fortunes of a state, which can translate into differences in the levels of taxes that must be collected from citizens. But their economic fortunes are only one component of what makes individual states unique. Theorists have long proposed that states are also unique as a function of their differing political cultures, or their attitudes and beliefs about the functions and expectations of the government. In the book, American Federalism: A View from the States , Daniel Elazar first theorized in 1966 that the United States could be divided into three distinct political cultures: moralistic, individualistic, and traditionalistic ( Figure 14.7 ). The diffusion of these cultures throughout the United States is attributed to the migratory patterns of immigrants who settled in and spread out across the country from the east to the west coast. These settlers had distinct political and religious values that influenced their beliefs about the proper role of government, the need for citizen involvement in the democratic process, and the role of political parties. MORALISTIC POLITICAL CULTURE In Elazar’s framework, states with a moralistic political culture see the government as a means to better society and promote the general welfare. They expect political officials to be honest in their dealings with others, put the interests of the people they serve above their own, and commit to improving the area they represent. The political process is seen in a positive light and not as a vehicle tainted by corruption. In fact, citizens in moralistic cultures have little patience for corruption and believe that politicians should be motivated by a desire to benefit the community rather than by a need to profit financially from service. Moralistic states thus tend to support an expanded role for government. They are more likely to believe government should promote the general welfare by allocating funds to programs that will benefit the poor. In addition, they see it as the duty of public officials to advocate for new programs that will benefit marginal citizens or solve public policy problems, even when public pressure to do so is nonexistent. The moralistic political culture developed among the Puritans in upper New England. After several generations, these settlers moved westward, and their values diffused across the top of the United States to the upper Great Lakes. In the middle of the 1800s, Scandinavians and Northern Europeans joined this group of settlers and reinforced the Puritans’ values. Together, these groups pushed further west through the northern portion of the Midwest and West and then along the West Coast. 18 States that identify with this culture value citizen engagement and desire citizen participation in all forms of political affairs. In Elazar’s model, citizens from moralistic states should be more likely to donate their time and/or resources to political campaigns and to vote. This occurs for two main reasons. First, state law is likely to make it easier for residents to register and to vote because mass participation is valued. Second, citizens who hail from moralistic states should be more likely to vote because elections are truly contested. In other words, candidates will be less likely to run unopposed and more likely to face genuine competition from a qualified opponent. According to Elazar, the heightened competition is a function of individuals’ believing that public service is a worthwhile endeavor and an honorable profession. Milestone Oregon’s Efforts to Expand the Voting Franchise In 1998, Oregon became the first state to switch to mail-in voting when citizens passed a ballot measure for it to take effect. In March 2015, Governor Kate Brown took another step to expand the voting franchise. She signed a bill into law that makes voter registration automatic for all citizens in the state with a driver’s license. These citizens will now be automatically registered to vote in elections and will receive a mail-in ballot before Election Day unless they specifically opt out with the Oregon secretary of state’s office. In the United States, Oregon is the first to institute automatic voter registration, and it anticipates adding several hundred thousand residents to its voter participation list with the passage of this bill. 19 However, the new law lacks the support of Republicans in the state legislature. These party members believe automatic registration makes the voting process too easy for citizens and coerces them into voting. 20 Others argue that Oregon’s new law is a positive move. They believe the change is a step in the right direction for democracy and will encourage participation in elections. If Oregon’s law were to be adopted across the United States, it would affect about fifty million citizens, the number who are believed to be eligible to vote but who remain unregistered. 21 What are the benefits of Oregon’s automatic voter registration policy? Are there any drawbacks? What advantages and disadvantages might arise if this policy were adopted nationwide? Finally, in Elazar’s view, citizens in moralistic cultures are more likely to support individuals who earn their positions in government on merit rather than as a reward for party loyalty. In theory, there is less incentive to be corrupt if people acquire positions based on their qualifications. In addition, moralistic cultures are more open to third-party participation. Voters want to see political candidates compete who are motivated by the prospect of supporting the broader community, regardless of their party identification. INDIVIDUALISTIC POLITICAL CULTURE States that align with Elazar’s individualistic political culture see the government as a mechanism for addressing issues that matter to individual citizens and for pursuing individual goals. People in this culture interact with the government in the same manner they would interact with a marketplace. They expect the government to provide goods and services they see as essential, and the public officials and bureaucrats who provide them expect to be compensated for their efforts. The focus is on meeting individual needs and private goals rather than on serving the best interests of everyone in the community. New policies will be enacted if politicians can use them to garner support from voters or other interested stakeholders, or if there is great demand for these services on the part of individuals. According to Elazar , the individualist political culture originated with settlers from non-Puritan England and Germany. The first settlements were in the mid-Atlantic region of New York, Pennsylvania, and New Jersey and diffused into the middle portion of the United States in a fairly straight line from Ohio to Wyoming. Given their focus on pursuing individual objectives, states with an individualistic mindset will tend to advance tax breaks as a way of trying to boost a state’s economy or as a mechanism for promoting individual initiative and entrepreneurship. For instance, New Jersey governor Chris Christie made headlines in 2015 when discussing the incentives he used to attract businesses to the state. Christie encouraged a number of businesses to move to Camden, where unemployment has risen to almost 14 percent, by providing them with hundreds of millions of dollars in tax breaks. 22 The governor hopes these corporate incentives will spur job creation for citizens who need employment in an economically depressed area of the state. Since this theoretical lens assumes that the objective of politics and the government is to advance individual interests, Elazar argues that individuals are motivated to become engaged in politics only if they have a personal interest in this area or wish to be in charge of the provision of government benefits. They will tend to remain involved if they get enjoyment from their participation or rewards in the form of patronage appointments or financial compensation. As a result of these personal motivations, citizens in individualistic states will tend to be more tolerant of corruption among their political leaders and less likely to see politics as a noble profession in which all citizens should engage. Finally, Elazar argues that in individualistic states, electoral competition does not seek to identify the candidate with the best ideas. Instead it pits against each other political parties that are well organized and compete directly for votes. Voters are loyal to the candidates who hold the same party affiliation they do. As a result, unlike the case in moralistic cultures, voters do not pay much attention to the personalities of the candidates when deciding how to vote and are less tolerant of third-party candidates. TRADITIONALISTIC POLITICAL CULTURE Given the prominence of slavery in its formation, a traditionalistic political culture , in Elazar’s argument, sees the government as necessary to maintaining the existing social order, the status quo. Only elites belong in the political enterprise, and as a result, new public policies will be advanced only if they reinforce the beliefs and interests of those in power. Elazar associates traditionalistic political culture with the southern portion of the United States, where it developed in the upper regions of Virginia and Kentucky before spreading to the Deep South and the Southwest. Like the individualistic culture, the traditionalistic culture believes in the importance of the individual. But instead of profiting from corporate ventures, settlers in traditionalistic states tied their economic fortunes to the necessity of slavery on plantations throughout the South. When elected officials do not prioritize public policies that benefit them, those on the social and economic fringes of society can be plagued by poverty and pervasive health problems. For example, although Figure 14.8 shows that poverty is a problem across the entire United States, the South has the highest incidence. According to the Centers for Disease Control and Prevention, the South also leads the nation in self-reported obesity, closely followed by the Midwest. 23 These statistics present challenges for lawmakers not only in the short term but also in the long term, because they must prioritize fiscal constraints in the face of growing demand for services. While moralistic cultures expect and encourage political participation by all citizens, traditionalistic cultures are more likely to see it as a privilege reserved for only those who meet the qualifications. As a result, voter participation will generally be lower in a traditionalistic culture, and there will be more barriers to participation (e.g., a requirement to produce a photo ID at the voting booth). Conservatives argue that these laws reduce or eliminate fraud on the part of voters, while liberals believe they disproportionally disenfranchise the poor and minorities and constitute a modern-day poll tax. Link to Learning Visit the National Conference of State Legislatures for an overview of Voter Identification Requirements by state. Finally, under a traditionalistic political culture, Elazar argues that party competition will tend to occur between factions within a dominant party. Historically, the Democratic Party dominated the political structure in the South before realignment during the civil rights era. Today, depending on the office being sought, the parties are more likely to compete for voters. CRITIQUES OF ELAZAR’S THEORY Several critiques have come to light since Elazar first introduced his theory of state political culture fifty years ago. The original theory rested on the assumption that new cultures could arise with the influx of settlers from different parts of the world; however, since immigration patterns have changed over time, it could be argued that the three cultures no longer match the country’s current reality. Today’s immigrants are less likely to come from European countries and are more likely to originate in Latin American and Asian countries. 24 In addition, advances in technology and transportation have made it easier for citizens to travel across state lines and to relocate. Therefore, the pattern of diffusion on which the original theory rests may no longer be accurate, because people are moving around in more, and often unpredictable, directions. It is also true that people migrate for more reasons than simple economics. They may be motivated by social issues such as widespread unemployment, urban decay, or low-quality health care of schools. Such trends may aggravate existing differences, for example the difference between urban and rural lifestyles (e.g., the city of Atlanta vs. other parts of Georgia), which are not accounted for in Elazar’s classification. Finally, unlike economic or demographic characteristics that lend themselves to more precise measurement, culture is a comprehensive concept that can be difficult to quantify. This can limit its explanatory power in political science research. 14.3 Governors and State Legislatures Learning Objectives By the end of this section, you will be able to: Identify the formal powers and responsibilities of modern-day governors List the basic functions performed by state legislatures Describe how state legislatures vary in size, diversity, party composition, and professionalism Public opinion regarding Congress has reached a dismal low, with more than 80 percent of those surveyed in 2014 saying they do not feel most members of Congress deserve to be reelected. 25 This attitude stems from partisan rivalry, media coverage that has capitalized on the conflict, fiscal shutdowns, and the general perception that Congress is no longer engaged in lawmaking. The picture looks quite different at the subnational level, at least where lawmaking is concerned. State representatives and senators have been actively engaged in the lawmaking function, grabbing national attention at times for their controversial and highly partisan policies. Governors have been active in promoting their own policy agendas, either in cooperation with the state legislature or in opposition to it. Among the early 2016 Republican presidential contenders, nine were current or former state governors. 26 Increasingly, governors are using their office and the policies they have signed into law as a platform to gain national attention and to give voters a sense of their priorities should they ascend to the highest office in the country, the presidency. GOVERNORS IN CHARGE Anyone elected to the office of governor assumes tremendous responsibility overnight. He or she becomes the spokesperson for the entire state and their political party, accepts blame or praise for handling decision-making in times of crisis, oversees the implementation of public policy, and helps shepherd legislation through the lawmaking process. These tasks require a great deal of skill and demand that governors exhibit different strengths and personality traits. Governors must learn to work well with other lawmakers, bureaucrats, cabinet officials, and with the citizens who elected them to office in the first place. The water crisis in Flint, Michigan, provides a good case in point. Governors have tremendous power over the legislative branch because they serve year-round and hold office alone. They also command wide press coverage by virtue of being the leading elected official in their state. Finally, while there are variations in degree across the states, most governors have more power relative to their state legislatures than does the U.S. president relative to the U.S. Congress. State executive power flows from factors such as the propensity of state legislatures to meet for only part of the year and their resulting reliance for information on the governor and his/her administration, stronger formal tools (e.g., line-item vetoes), budget-cutting discretion, and the fact that state legislators typically hold down another job besides that of legislator. Three of the governor’s chief functions are to influence the legislative process through an executive budget proposal, a policy agenda, and vetoes. Just as the president gives a State of the Union address once a year, so too do governors give an annual State of the State address before the state legislature ( Figure 14.9 ). In this speech, they discuss economic and political achievements, cite data that supports their accomplishments, and overview the major items on their legislative agenda. This speech signals to members of the state legislature what priorities are high on the governor’s list. Those who share the governor’s party affiliation will work with him or her to see these goals achieved. Given that governors need the cooperation of state legislators to get their bills introduced and steered through the lawmaking process, they make developing good relationships with lawmakers a priority. This can entail helping lawmakers address the concerns of their constituents, inviting legislators to social events and meals, and scheduling weekly meetings with legislative leaders and committee chairs to discuss policy. 27 In addition to providing a basic list of policy priorities, governors also initiate a budget proposal in most states. Here they indicate funding priorities and spell out the amounts that will be appropriated to various state agencies under their discretion. When the economy is strong, governors may find themselves in the enviable position of having a surplus of tax revenue. That allows them some flexibility to decide whether they want to reduce taxes, direct funds toward a new initiative or program, allocate more funds to current programs, restore funds that were cut during times of fiscal distress, or save surplus revenue in a rainy-day account. 28 Moreover, when cuts must be made, especially when the legislature is not in session, it is typically the governor or his or her finance director who makes the call on what gets cut. Having introduced his or her priorities, the governor will work on the sidelines to steer favored bills through the legislative process. This may entail holding meetings with committee chairs or other influential lawmakers concerning their legislative priorities, working with the media to try to get favorable coverage of legislative priorities, targeting advocacy organizations to maintain pressure on resistant lawmakers, or testifying in legislative hearings about the possible impacts of the legislation. 29 Once legislation has made its way through the lawmaking process, it comes to the governor’s desk for signature. If a governor signs the bill, it becomes law, and if the governor does not like the terms of the legislation he or she can veto, or reject, the entire bill. The bill can then become law only if a supermajority of legislators overrides the veto by voting in favor of the bill. Since it is difficult for two-thirds or more of state legislators to come together to override a veto (it requires many members of the governor’s own party to vote against him or her), the simple act of threatening to veto can be enough to get legislators to make concessions to the governor before he or she will pass the legislation. The ability to veto legislation is just one of the formal powers governors have at their disposal. Formal powers are powers the governor may exercise that are specifically outlined in state constitutions or state law. 30 Unlike U.S. presidents, many governors also have additional veto powers at their disposal, which enhances their ability to check the actions of the legislative branch. For instance, most states provide governors the power of the line-item veto. The line-item veto gives governors the ability to strike out a line or individual portions of a bill while letting the remainder pass into law. In addition, approximately 30 percent of governors have the power of an amendatory veto , which allows them to send a bill back to the legislature and request a specific amendment to it. Finally, a small number of governors, including the governor of Texas, also have the power of a reduction veto , which allows them to reduce the budget proposed in a piece of legislation. 31 Insider Perspective The Vanna White and Frankenstein Vetoes in Wisconsin Although the line-item, reduction, and amendatory vetoes give governors tremendous power to adjust legislation and to check the legislative branch, the most powerful and controversial vetoes, which have allowed governors to make selective deletions from a bill before signing, are dubbed the “Vanna White” veto and the “Frankenstein” veto. (Vanna White hosts the popular game show “Wheel of Fortune,” in which contestants guess what a phrase is based on a limited number of letters. As they guess the letters, White indicates the correct letters within the puzzle.) These powers have a colorful history in the state of Wisconsin, where voters have limited their influence on two occasions. The first occurred in 1990 when voters passed a provision restricting the governor’s ability to use the “Vanna White” veto to change a bill by crossing out specific letters within a given word in order to create a new word. After this restriction took effect, the “Frankenstein” veto came into practice, which allowed a governor to remove individual words, numbers, or passages from a bill and string the remaining text together (like the fictional Dr. Frankenstein’s monster) in an effort to alter the original intent of the legislation. 32 As an example of the Frankenstein veto, when an appropriations bill was sent to Wisconsin governor James E. Doyle for signature in 2005, Doyle scrapped over seven hundred words from a passage that would have appropriated millions of dollars to transportation. The words that remained in the bill redirected those funds to education. Lawmakers were outraged, but they were not able to override the veto. 33 Then, in 2007, Governor Doyle used the veto once again to raise property taxes almost 2 percent. 34 As a result of these controversial moves, the state house and senate passed a referendum to end the ability of governors to create a new sentence by combining words from two or more other sentences. A legislative referendum is a measure passed by the state legislature, such as a constitutional amendment, that goes to the voters for final approval. 35 This referendum went to the voters for approval or rejection in the 2008 election, and the voters banned the practice. Governors in Wisconsin and all the states still have tremendous power to shape legislation, however, through the other types of vetoes discussed in this chapter. Should any state governor have the powers referred to as the “Vanna White” and “Frankenstein” vetoes? What advantage, if any, might state residents gain from their governor’s ability to alter the intent of a bill the legislature has approved and then sign it into law? Besides the formal power to prepare the budget and veto legislation, legislators also have the power to call special sessions of the legislature for a wide array of reasons. For instance, sessions may be called to address budgetary issues during an economic downturn, to put together a redistricting plan, or to focus intensively on a particular issue the governor wants rectified immediately. 36 In some states, only the governor has the power to call a special session, while in other states this power is shared between the legislative and the executive branches. Link to Learning For more details on the calling of legislative Special Sessions , visit the National Conference of State Legislatures website. Although governors have a great deal of power in the legislative arena, this is not their only area of influence. First, as leaders in their political party, governors often work to raise money for other political figures who are up for reelection. A governor who has high public approval ratings may also make campaign appearances on behalf of candidates in tough reelection fights across the state. Governors can draw in supporters, contributions, and media attention that can be beneficial to other political aspirants, and the party will expect them to do their part to ensure the greatest possible number of victories for their candidates. Second, as the spokesperson for their state, governors make every effort to sell the state’s virtues and unique characteristics, whether to the media, to other citizens across the United States, to potential business owners, or to legislative leaders in Washington, DC. Governors want to project a positive image of their state that will encourage tourism, relocation, and economic investment within its boundaries. Collectively, governors make a mark through the National Governors Association , which is a powerful lobbying force in the nation’s capital. For example, Texas governor Greg Abbott made headlines in 2015 for writing to the CEO of General Electric (GE), urging the company to relocate its corporate headquarters from Connecticut, which had just raised its corporate tax rate, to Texas. 37 As his state’s spokesperson, Abbott promoted Texas’s friendly corporate tax structure and investment in transportation and education funding in hopes of enticing GE to relocate there and bring economic opportunities with it. The company has since decided to relocate to Boston, after receiving incentives, worth up to $145 million, from Massachusetts officials. 38 Another example involved Texas governor Rick Perry touring California in 2014 in order to bring prospective businesses from the Golden State to Texas. In March 2015, the governor of Virginia, Terry McAuliffe , and the mayor of Chicago, Rahm Emanuel , both sent letters to corporate heads in Indiana after controversy erupted around the passage of that state’s Religious Freedom Restoration Act . 39 This bill is designed to restrict government intrusion into people’s religious beliefs unless there is a compelling state interest. It also provides individuals and businesses with the ability to sue if they feel their religious rights have been violated. However, opponents feared the law would be used as a means to discriminate against members of the LGBT community, based on business owners’ religious objections to providing services for same-sex couples. 40 In the media firestorm that followed the Indiana law’s passage, several prominent companies announced they would consider taking their business elsewhere or cancelling event contracts in the state if the bill were not amended. 41 This led opportunistic leaders in the surrounding area to make appeals to these companies in the hope of luring them out of Indiana. Ultimately, the bill was clarified, likely due in part to corporate pressure on the state to do so. 42 The clarification made it clear that the law could not be used to refuse employment, housing, or service based on an individual’s sexual orientation or gender identity. 43 Controversial legislation like the Religious Freedom Restoration Act is only one of the many environmental factors that can make or break a governor’s reputation and popularity. Other challenges and crises that may face governors include severe weather, terrorist attacks, immigration challenges, and budget shortfalls. New Jersey governor Chris Christie gained national attention in 2012 over his handling of the aftermath of Hurricane Sandy, which caused an estimated $65 billion worth of damage and cost the lives of over 150 individuals along the East Coast of the United States. 44 Christie was famously photographed with President Obama during their joint tour of the damaged areas, and the governor subsequently praised the president for his response ( Figure 14.10 ). Some later criticized Christie for his remarks because of the close proximity between the president’s visit and Election Day, along with the fact that the Republican governor and Democratic president were from opposite sides of the political aisle. Critics felt the governor had betrayed his party and that the publicity helped the president win reelection. 45 Others praised the governor for cooperating with the president and reaching across the partisan divide to secure federal support for his state in a time of crisis. 46 If severe winter weather is forecasted or in the event of civil unrest, governor s also have the power to call upon the National Guard to assist residents and first responders or aid in storm recovery ( Figure 14.11 ). When governors declare a state of emergency, National Guard troops can be activated to go into local areas and assist with emergency efforts in whatever capacity they are needed. 47 In 2015, many governors in the New England region called press conferences, worked with snow-removal crews and local government officials, set up emergency shelters, and activated travel bans or curfews in the face of crippling snowstorms. 48 When winter storms fail to bring predicted levels of snow, however, politicians can be left to field criticism that they instigated unnecessary panic. 49 Governors feel the weight of their decisions as they try to balance the political risks of overreacting and the human costs of letting the state be caught unprepared for these and other major natural disasters. As the chief spokesperson, they take all the blame or all the credit for their actions. With that said, it is important to note that presidents can enlist the National Guard for federal service as well. Governors also have the power to spare or enhance the lives of individuals convicted of crimes in their state. Although they may choose to exercise this formal power only during the closing days of their term, if at all, most governors have the authority to grant pardons just as U.S. presidents do. A pardon absolves someone of blame for a crime and can secure his or her release from prison. Governors can also commute sentences, reducing the time an individual must serve, 50 if there are doubts about the person’s guilt, concerns about his or her mental health, or reason to feel the punishment was inappropriately harsh. In the past ten years, the governors of New Jersey and Illinois have commuted the sentences of all inmates on death row before repealing the death penalty in their states. 51 Despite the tremendous formal powers that go with the job, being governor is still personally and professionally challenging. The demands of the job are likely to restrict time with family and require forgoing privacy. In addition, governors will often face circumstances beyond their control. For instance, the state legislature may include a majority of members who do not share the governor’s party affiliation. This can make working together more challenging and lead to less cooperation during the legislative session. Another challenge for governors is the plural executive, which refers to the fact that many state officials, such as the lieutenant governor, attorney general, and secretary of state are elected independently from the governor; hence, the governor has no direct control over them the way a president might have sway over U.S. executive officials. Governors can also face spending restrictions due to the economic climate in their state. They may have to make unpopular decisions that weaken their support among voters. The federal government can mandate that states perform some function without giving them any funds to do so. Finally, as we saw above, governors can be swept up in crises or natural disasters they did not anticipate and could not have foreseen. This can drain their energy and hamper their ability to generate good public policy. 52 THE FUNCTIONS OF STATE LEGISLATURES State legislatures serve three primary functions. They perform a lawmaking function by researching, writing, and passing legislation. Members represent their districts and work to meet requests for help from citizens within it. Finally, legislatures perform an oversight function for the executive branch. All state representatives and senators serve on committees that examine, research, investigate, and vote on legislation that relates to the committee’s purpose, such as agriculture, transportation, or education. The number of bills introduced in any given session varies. Some state legislature s have more restrictive rules concerning the number of bills any one member can sponsor. Legislators get ideas for bills from lobbyists of various types of interest groups, ranging from corporate groups to labor unions to advocacy organizations. Ideas for bills also come from laws passed in other state legislatures, from policy that diffuses from the federal government, from constituents or citizens in the officeholder’s district who approach them with problems they would like to see addressed with new laws, and from their own personal policy agenda, which they brought to office with them. Finally, as we explored previously, legislators also work with the governor’s agenda in the course of each legislative session, and they must pass a budget for their state either every year or every two years. Most bills die in committee and never receive a second or third reading on the floor of the legislature. Lawmaking requires frequent consensus, not just among the legislators in a given house but also between the two chambers. In order for a bill to become law, it must pass through both the state house and the state senate in identical form before going to the governor’s desk for final signature. Besides generating public policy, state legislatures try to represent the interests of their constituents. Edmund Burke was a political philosopher who theorized that representatives are either delegates or trustees. 53 A delegate legislator represents the will of those who elected him or her to office and acts in their expressed interest, even when it goes against personal belief about what is ultimately in the constituency’s best interest. On the other hand, trustee s believe they were elected to exercise their own judgment and know best because they have the time and expertise to study and understand an issue. Thus, a trustee will be willing to vote against the desire of the constituency so long as he or she believes it is in the people’s best interest. A trustee will also be more likely to vote his or her conscience on issues that are personal to him or her, such as on same-sex marriage or abortion rights. Regardless of whether representatives adopt a delegate or a trustee mentality, they will all see it as their duty to address the concerns and needs of the people they represent. Typically, this will entail helping members in the district who need assistance or have problems with the government they want addressed. For instance, a constituent may write an elected official asking for help dealing with the bureaucracy such as in a decision made by tax commission, requesting a letter of recommendation for acceptance into a military academy, or proposing a piece of legislation the member can help turn into a law. Legislators also try to bring particularized benefits back to their district. These benefits might include money that can be spent on infrastructure improvements or grants for research. Finally, members will accept requests from local government officials or other constituents to attend parades, ribbon-cutting ceremonies, or other celebratory events within their district ( Figure 14.12 ). They will also work with teachers and faculty to visit classes or meet with students on field trips to the state capitol. The last primary function of state legislators is to oversee the bureaucracy’s implementation of public policy, ensuring it occurs in the manner the legislature intended. State legislatures may request that agency heads provide testimony about spending in hearings, or they may investigate particular bureaucratic agencies to ensure that funds are being disbursed as desired. 54 Since legislators have many other responsibilities and some meet for only a few months each year, they may wait to investigate until a constituent or lobbyist brings a problem to their attention. THE COMPOSITION OF STATE LEGISLATURES In most states, the legislative function is divided between two bodies: a state house and a state senate. The only exception is Nebraska, which has a unicameral state senate of forty-nine members. State legislatures vary a great deal in terms of the number of legislators in the house and senate, the range of diversity across the membership, the partisan composition of the chamber relative to the governor’s affiliation, and the degree of legislative professionalism. This variation can lead to differences in the type of policies passed and the amount of power legislatures wield relative to that of the governor. According to the National Conference of State Legislatures , at forty members, Alaska’s is the smallest state (or lower) house, while New Hampshire’s is the largest at four hundred. State senates range in size from twenty members in Alaska to sixty-seven members in Minnesota. The size of the institution can have consequences for the number of citizens each member represents; larger bodies have a smaller legislator-to-constituent ratio (assuming even populations). Larger institutions can also complicate legislative business because reaching consensus is more difficult with more participants. 55 The term length in the state house is frequently two years, while in the state senate it is more commonly four years. These differences have consequences, too, because representatives in the state house, with the next election always right around the corner, will need to focus on their reelection campaigns more frequently than senators. On the other hand, state senators may have more time to focus on public policy and become policy generalists because they each must serve on multiple committees due to their smaller numbers. Link to Learning The number of legislators and term length varies by state. In 2015, according to the National Conference of State Legislatures, women made up 24.3 percent of the nation’s state legislators. However, the number varies a great deal across states ( Figure 14.13 ). For instance, in Colorado and Vermont, women account for just over 40 percent of the state legislative membership. However, they make up less than 15 percent of the legislatures in Alabama, Louisiana, Oklahoma, South Carolina, West Virginia, and Wyoming. 56 Data on minority representatives is more difficult to obtain, but 2009 estimates from the National Conference of State Legislatures paired with census estimates from 2010 show that African Americans and Latinos are both underrepresented in state government relative to their percentage of the population. In 2009, African Americans made up approximately 9 percent of state legislators, compared to the 13 percent of the population they constitute nationwide. On the other hand, Latino representatives made up approximately 3 percent of state legislators relative to their 14 percent of the total population in the United States. 57 The proportion of Latinos in the legislature is highest in Arizona, California, New Mexico, and Texas, while the proportion of African Americans is highest in Alabama, Georgia, and Mississippi. Scholars in political science have spent a great deal of time researching the impact of women and minorities on the legislative process and on voter participation and trust. Some research demonstrates that female and minority representatives are more likely to advocate for policies that are of interest to or will benefit minorities, women, and children. 58 Other research suggests that the presence of African American and Latino representatives increases voter turnout by these groups. 59 Thus, increased diversity in state legislature s can have consequences for voter engagement and for the type of legislation pursued and passed within these bodies. Link to Learning You can compare the numbers and percentages of women in state legislature , state by state. You can also compare the numbers and percentages of African American representatives . Similar information about Latino representation in state legislatures is also available. In 2014, twenty-six states had Republican majorities in the state house and senate, while in twenty states Democratic majorities were the norm. In just four states, party control was split so that the Democratic Party maintained control of one house while the Republican Party maintained control of the other. 60 Figure 14.14 illustrates the partisan composition across the United States. Note that states in New England and the West Coast are more likely to be unified behind the Democratic Party, while Republicans control legislatures throughout the South and in large parts of the Midwest. This alignment largely reflects differing political ideologies, with the more liberal, urban areas of the country leaning Democratic while the more conservative, rural areas are Republican. Like diversity, party composition has consequences for policymaking. Governors who are not from the same party as the one controlling the legislature can find it more difficult to achieve their agenda. This governing circumstance is popularly referred to as divided government . In a time of divided government, a governor may have to work harder to build relationships and to broker consensus. In addition, when state party control is divided between the legislative and executive branches, the governor may find that legislators are more likely to muster the numbers to overturn at least some of their vetoes. In contrast, when the governor’s own party controls the legislature—a situation known as unified government —conventional wisdom suggests that they will have a smoother and more productive relationship with the legislature. Party composition also matters for the overall legislative agenda. The party in power will elect party members to the top leadership posts in the state house and senate, and it will determine who sits on each of the committees. Committees are chaired by members of the majority party, and the composition of these committees is skewed toward members affiliated with the party in power. This gives the majority party an advantage in meeting its policy objectives and relegates the minority party to the position of obstructionists. In addition, while Republicans and Democrats are both concerned about education, health care, transportation, and other major policy areas, the two parties have different philosophies about what is in the best interest of their citizens and where funds should be allocated to meet those needs. The result is vastly different approaches to handling pressing public policy problems across the states. As a whole, state legislatures have become progressively more professional. Political scientist Peverill Squire , at several points throughout his career, has measured the degree of state legislative professionalism with a ranking across the fifty states. 61 Legislative professionalism is assessed according to three key factors: state legislators’ salary, the length of time they are in session, and the number of staff at their disposal. Members of professional or full-time legislatures tend to consider legislative service their full-time occupation, and they are paid enough not to require a second occupation. They also have larger staffs to assist with their work, and they tend to be in session for much of the year. On the other end of the spectrum are citizen, or part-time, legislatures. Representatives and senators in these legislatures do not enjoy the same perks as their counterparts in professional legislatures. Generally, salary is much lower and so is staff assistance. Members typically need to seek outside employment to supplement their income from legislative work, and the legislature will meet for only a brief period of time during the year. Between these two extremes are hybrid legislatures. Their members are compensated at a higher rate than in citizen legislatures, but they are still likely to need outside employment to make an income equal to what they were making prior to taking office. These representatives and senators will have some staff assistance but not as much as in a professional legislature. Finally, members in hybrid legislatures will not consider their service to constitute a full-time occupation, but they will spend more than part of their time conducting legislative business. As Figure 14.15 shows, California, New York, and Pennsylvania are home to some of the most professional legislatures in the country. On the other hand, New Hampshire, North Dakota, Wyoming, and South Dakota are among the states that rank lowest on legislative professionalism. 62 Like the other indicators discussed above, legislative professionalism also affects the business of state legislatures. In professional legislatures, elections tend to be more competitive, and the cost of running for a seat is higher because the benefits of being elected are greater. This makes these seats more attractive, and candidates will tend not to run unless they perceive themselves as well qualified. Since the benefits are more generous, elected officials will tend to stay in office longer and develop more policy expertise as a result. This experience can give professional legislatures an edge when dealing with the governor, because they are likely to be in session for about the same amount of time per year as the governor and have the necessary staff to assist them with researching and writing public policy. 63 Link to Learning The legislative pay varies across states. Compare the size of legislative staffs across states for the years 1979, 1988, 1996, 2003, and 2009. 14.4 State Legislative Term Limits Learning Objectives By the end of this section, you will be able to: Describe the history of state legislative term limits Compare the costs and benefits of term limits Term limits restrict the length of time a member can serve in the state legislature by capping either lifetime service or the number of consecutive terms. The term limits movement gained momentum in the 1990s, spreading across a wide array of state legislative institutions. Today, fifteen states have imposed term limits on their state house and state senate members. On the other hand, six states, one as recently as 2004, have repealed the term limits imposed on them by the electorate, through either judicial action in the state Supreme Courts or through legislative action in the state legislature. 64 THE BASICS OF TERM LIMITS Under consecutive term limits , a member can serve for only a specified period of time in either the state house or the state senate, most commonly eight years. To try to regain a seat in the legislature once the limit has been met, the member will have to wait to run for office again. If the member succeeds, the clock will reset and the legislator may once again serve up to the limit set by the state. In states with a lifetime ban , such as Oklahoma, members can serve only one time for the number of years allotted, and they are not permitted to run for office again ( Figure 14.16 ). 65 The first term limits were enacted in 1990 in California, Colorado, and Oklahoma. In 1992, eight more states followed suit in one large wave. The last state to enact term limits on legislative members was Nebraska in 2000. 66 However, term limits did not stay in effect in all these states; many state supreme courts repealed them and declared them unconstitutional for a variety of reasons ( Figure 14.17 ). For instance, in Massachusetts and Washington, term limits were deemed unconstitutional because they affected candidate qualifications to compete for a given office. The courts ruled that changes to those qualifications could be made only by amending the state constitution, not by voters changing the state law. 67 ADVANTAGES OF TERM LIMITS In many cases, the movement to institute term limits was initiated by voters and passed through citizen initiatives, which allow citizens to place a proposed law or constitutional amendment on the ballot for a popular vote. 68 Proponents of term limits felt new blood was needed in state legislatures to bring fresh ideas and perspectives to lawmaking. In addition, they hoped term limits would compel turnover among members by shortening the time anyone could serve and by reducing the tendency for elected officials to make legislative service their career. In conjunction with this thinking, some supporters hoped term limits would increase the motivation to make good public policy. If members were less focused on reelection and knew they could not serve more than a certain number of years, perhaps they would get right down to the business of making laws and produce innovative policy within a narrow window of time. 69 For other proponents, the hope was that term limits would increase diversity within the chamber by encouraging more women, members of racial and ethnic minority groups, members of the minority party, and people with unconventional occupations to run for office because seats would be open more frequently. In addition, supporters speculated that increased turnover might prompt higher rates of electoral competition and voter interest. Finally, they believed the loss of long-term legislators due to term limits would allow new members and younger legislators to assume leadership positions within the chamber and committees, creating another way to bring fresh approaches to the lawmaking process. 70 Get Connected! Working to Expand Term Limits One pro–term limits advocacy group, U.S. Term Limits , is dedicated to the expansion of term limits across the United States. Its members work to prevent states from repealing limits that are already in place. They also support efforts by citizens to institute term limits in states where they are not currently in place, and in Congress, where the Supreme Court declared them unconstitutional. 71 If you support their cause, you can follow the link below to learn more about these efforts or to participate directly. Write a letter to the editor encouraging the adoption of term limits in a given state, or encourage your member of Congress to sign a pledge agreeing to cosponsor and vote for an amendment to the Constitution to adopt term limits. You can also sign an online petition to support the adoption of term limits at the federal level or make a donation to a term-limit advocacy group. What is your state’s policy on term limits? If limits are in place, how have they changed your representation in the state capitol? If they are not in place, what effect would adopting them have on your representation? There is no comparable national movement against term limits, why do you think that is the case? Based on your answers, do you favor term limits or not, and why? Link to Learning For more information about supporting term limits, visit U.S. Terms , an advocacy group for term limits. DISADVANTAGES OF TERM LIMITS Although proponents have many reasons for supporting term limits, opponents also have compelling reasons for not supporting their implementation in the state legislature. In addition, research by political scientists has uncovered a number of negative consequences since term limits took effect. Although proponents argued that term limits would increase legislative diversity, research comparing the rate of female and minority representation in term-limited and non-term-limited states does not bear out this expectation. There is no statistically significant difference in diversity between the two groups of states. 72 Although term limits may have produced more open seats, additional barriers to holding office can still exist and affect the willingness of women and minorities to run for office. In addition, women and minorities are subject to the same term limits as men, and given their low numbers among candidates for office, on balance a legislature can lose more women or minorities than it gains. Term limits also affect the power structure between the legislative and executive branches and the key sources from whom legislators draw information about bills before the chamber. Research demonstrates that, post-term limits, legislators became more likely to consult with lobbyists to gain information about legislation under consideration than had been the case before term limits. 73 This is likely the result of legislators having less policy expertise and political experience as a function of having fewer years in office, being younger when they first enter legislative service, reducing institutional memory and expertise within the chamber as a whole due to member turnover, or all the above. Interest groups may thus enjoy greater ability to set the agenda and push for policy that favors their organization. This same research also found that under term limits state legislators feel they have lost power relative to the governor and to various bureaucratic agency officials. 74 This presumed loss of power could damage the state legislature’s ability to adequately check the actions of the executive branch and to perform legislative functions, such as oversight. Finally, term limits could affect voter enthusiasm and turnout if voters are disappointed they cannot retain legislators they like or have developed a positive relationship with. Once term limits take effect, all legislators are at the voters’ mercy, regardless of the skill or talent they may bring to the office. 14.5 County and City Government Learning Objectives By the end of this section, you will be able to: Identify the differences between county and municipal governments in terms of their responsibilities and funding sources Describe the two primary types of municipal government and the three basic types of county government County and city governments make up an important component of the overall structure of the government. Not only do they affect citizens directly; it is also easier for citizens to interact with local government officials because their offices and the community’s school board or city council meetings are often close by. Despite this fact, voter turnout in local elections tends to be lower than in state and national elections. Municipal and county governments differ in structure and purpose in several ways. COUNTY GOVERNMENT County governments serve a larger geographical area than cities and towns, but a smaller area than states. They are created by the state government and typically operate under provisions set out in the state constitution. As such, they are essentially administrative units of the state. Census estimates from 2012 indicate that there are just over three thousand counties in the United States. 75 County systems usually take one of three basic forms: the commission system, the council-administrator system, and the council-elected executive system. The most common form of county government is the commission system . Under this structure, an elected commission, which generally consists of a small number of commissioners, serves as the governing body within the county, performing all legislative and executive functions. These include adopting a budget, passing county resolutions, and hiring and firing county officials. 76 Under the council-administrator system , the voters elect council members to serve for a specified period of time, and the council in turn appoints an administrator to oversee the operation of the government. The administrator serves at the directive of the council and can be terminated by the council. The goal of this arrangement is to divide administrative and policymaking responsibilities between the elected council and the appointed administrator. 77 Under a council-elected executive system , the voters elect both the members of the council and the executive. The executive performs functions similar to those of the state governor. For instance, he or she can veto the actions of the council, draft a budget, and provide suggestions regarding public policy. 78 Although the tasks they perform can vary from state to state, most counties have a courthouse that houses county officials, such as the sheriff, the county clerk, the assessor, the treasurer, the coroner, and the engineer. These officials carry out a variety of important functions and oversee the responsibilities of running a county government. For instance, the county coroner investigates the cause of death when suspicious circumstances are present. The county clerk oversees the registration of voters and also certifies election results for the county. In addition, this officeholder typically keeps the official birth, death, and marriage records. The county treasurer oversees the collection and distribution of funds within the county, while the county assessor conducts property tax evaluations and informs individual citizens or business owners of their right to contest the appraised value of their property. Finally, a county engineer will oversee the maintenance and construction of county infrastructure. 79 In short, counties help to maintain roads and bridges, courthouses and jails, parks and pools, and public libraries, hospitals, and clinics. 80 To provide these services, county governments typically rely on property tax revenue, a portion of sales tax receipts, and funds from intergovernmental transfers by way of federal or state grants. CITY GOVERNMENT Municipal governments oversee the operation and functions of cities and towns. Census estimates for 2012 show just over 19,500 municipal governments and nearly 16,500 township governments in the United States. 81 The vast majority of municipal government s operate on one of two governing models: a mayor-council system or a council-manager system. Under the mayor-council system voters elect both a mayor and members of the city council. The city council performs legislative functions and the mayor the executive functions. Under this system, the mayor may be given a great deal of authority or only limited powers. 82 Under a strong mayor system, the mayor will be able to veto the actions of the council, appoint and fire the heads of city departments, and produce a budget. Under a weak mayor system, the mayor has little authority compared to the council and acts in a ceremonial capacity as a spokesperson for the city. 83 In a council-manager system of government, either the members of the city council are elected by voters along with a mayor who presides over the council, or the voters elect members of the city council and the mayor is chosen from among them. In either case, the city council will then appoint a city manager to carry out the administrative functions of the municipal government. This frees the city council to address political functions such as setting policy and formulating the budget. 84 Municipal governments are responsible for providing clean water as well as sewage and garbage disposal. They must maintain city facilities, such as parks, streetlights, and stadiums ( Figure 14.18 ). In addition, they address zoning and building regulations, promote the city’s economic development, and provide law enforcement, public transportation, and fire protection. Municipal governments typically rely on property tax revenue, user fees from trash collection and the provision of water and sewer services, a portion of sales tax receipts, and taxes on business. Link to Learning The International City/County Management Association (ICMA) provides networking opportunities, professional development, and statistical data in order to support local government leaders and other individuals throughout the world. Visit the ICMA Priorities page to learn what makes a better leader and how you might improve your local community.
psychology
Summary 2.1 Why Is Research Important? Scientists are engaged in explaining and understanding how the world around them works, and they are able to do so by coming up with theories that generate hypotheses that are testable and falsifiable. Theories that stand up to their tests are retained and refined, while those that do not are discarded or modified. In this way, research enables scientists to separate fact from simple opinion. Having good information generated from research aids in making wise decisions both in public policy and in our personal lives. 2.2 Approaches to Research The clinical or case study involves studying just a few individuals for an extended period of time. While this approach provides an incredible depth of information, the ability to generalize these observations to the larger population is problematic. Naturalistic observation involves observing behavior in a natural setting and allows for the collection of valid, true-to-life information from realistic situations. However, naturalistic observation does not allow for much control and often requires quite a bit of time and money to perform. Researchers strive to ensure that their tools for collecting data are both reliable (consistent and replicable) and valid (accurate). Surveys can be administered in a number of ways and make it possible to collect large amounts of data quickly. However, the depth of information that can be collected through surveys is somewhat limited compared to a clinical or case study. Archival research involves studying existing data sets to answer research questions. Longitudinal research has been incredibly helpful to researchers who need to collect data on how people change over time. Cross-sectional research compares multiple segments of a population at a single time. 2.3 Analyzing Findings A correlation is described with a correlation coefficient, r , which ranges from -1 to 1. The correlation coefficient tells us about the nature (positive or negative) and the strength of the relationship between two or more variables. Correlations do not tell us anything about causation—regardless of how strong the relationship is between variables. In fact, the only way to demonstrate causation is by conducting an experiment. People often make the mistake of claiming that correlations exist when they really do not. Researchers can test cause-and-effect hypotheses by conducting experiments. Ideally, experimental participants are randomly selected from the population of interest. Then, the participants are randomly assigned to their respective groups. Sometimes, the researcher and the participants are blind to group membership to prevent their expectations from influencing the results. In ideal experimental design, the only difference between the experimental and control groups is whether participants are exposed to the experimental manipulation. Each group goes through all phases of the experiment, but each group will experience a different level of the independent variable: the experimental group is exposed to the experimental manipulation, and the control group is not exposed to the experimental manipulation. The researcher then measures the changes that are produced in the dependent variable in each group. Once data is collected from both groups, it is analyzed statistically to determine if there are meaningful differences between the groups. Psychologists report their research findings in peer-reviewed journal articles. Research published in this format is checked by several other psychologists who serve as a filter separating ideas that are supported by evidence from ideas that are not. Replication has an important role in ensuring the legitimacy of published research. In the long run, only those findings that are capable of being replicated consistently will achieve consensus in the scientific community. 2.4 Ethics Ethics in research is an evolving field, and some practices that were accepted or tolerated in the past would be considered unethical today. Researchers are expected to adhere to basic ethical guidelines when conducting experiments that involve human participants. Any experiment involving human participants must be approved by an IRB. Participation in experiments is voluntary and requires informed consent of the participants. If any deception is involved in the experiment, each participant must be fully debriefed upon the conclusion of the study. Animal research is also held to a high ethical standard. Researchers who use animals as experimental subjects must design their projects so that pain and distress are minimized. Animal research requires the approval of an IACUC, and all animal facilities are subject to regular inspections to ensure that animals are being treated humanely.
Chapter Outline 2.1 Why Is Research Important? 2.2 Approaches to Research 2.3 Analyzing Findings 2.4 Ethics Introduction Have you ever wondered whether the violence you see on television affects your behavior? Are you more likely to behave aggressively in real life after watching people behave violently in dramatic situations on the screen? Or, could seeing fictional violence actually get aggression out of your system, causing you to be more peaceful? How are children influenced by the media they are exposed to? A psychologist interested in the relationship between behavior and exposure to violent images might ask these very questions. The topic of violence in the media today is contentious. Since ancient times, humans have been concerned about the effects of new technologies on our behaviors and thinking processes. The Greek philosopher Socrates, for example, worried that writing—a new technology at that time—would diminish people’s ability to remember because they could rely on written records rather than committing information to memory. In our world of quickly changing technologies, questions about the effects of media continue to emerge. Many of us find ourselves with a strong opinion on these issues, only to find the person next to us bristling with the opposite view. How can we go about finding answers that are supported not by mere opinion, but by evidence that we can all agree on? The findings of psychological research can help us navigate issues like this.
[ { "answer": { "ans_choice": 3, "ans_text": "testable" }, "bloom": null, "hl_context": "<hl> Scientific research ’ s dependence on falsifiability allows for great confidence in the information that it produces . <hl> <hl> Typically , by the time information is accepted by the scientific community , it has been tested repeatedly . <hl> <hl> A hypothesis is a testable prediction about how the world will behave if our idea is correct , and it is often worded as an if-then statement ( e . g . , if I study all night , I will get a passing grade on the test ) . <hl> The hypothesis is extremely important because it bridges the gap between the realm of ideas and the real world . As specific hypotheses are tested , theories are modified and refined to reflect and incorporate the result of these tests Figure 2.5 .", "hl_sentences": "Scientific research ’ s dependence on falsifiability allows for great confidence in the information that it produces . Typically , by the time information is accepted by the scientific community , it has been tested repeatedly . A hypothesis is a testable prediction about how the world will behave if our idea is correct , and it is often worded as an if-then statement ( e . g . , if I study all night , I will get a passing grade on the test ) .", "question": { "cloze_format": "Scientific hypotheses are ________ and falsifiable.", "normal_format": "Which of the following is correct about scientific hypotheses?", "question_choices": [ "observable", "original", "provable", "testable" ], "question_id": "fs-idp5620448", "question_text": "Scientific hypotheses are ________ and falsifiable." }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 1, "ans_text": "facts" }, "bloom": null, "hl_context": "In the end , research is what makes the difference between facts and opinions . <hl> Facts are observable realities , and opinions are personal judgments , conclusions , or attitudes that may or may not be accurate . <hl> In the scientific community , facts can be established only using evidence collected through empirical research . The Process of Scientific Research Scientific knowledge is advanced through a process known as the scientific method . Basically , ideas ( in the form of theories and hypotheses ) are tested against the real world ( in the form of empirical observations ) , and those empirical observations lead to more ideas that are tested against the real world , and so on . In this sense , the scientific process is circular . The types of reasoning within the circle are called deductive and inductive . In deductive reasoning , ideas are tested against the empirical world ; in inductive reasoning , empirical observations lead to new ideas ( Figure 2.4 ) . These processes are inseparable , like inhaling and exhaling , but different research approaches place different emphasis on the deductive and inductive aspects .", "hl_sentences": "Facts are observable realities , and opinions are personal judgments , conclusions , or attitudes that may or may not be accurate .", "question": { "cloze_format": "________ are defined as observable realities.", "normal_format": "Which are defined as observable realities?", "question_choices": [ "behaviors", "facts", "opinions", "theories" ], "question_id": "fs-idp7218128", "question_text": "________ are defined as observable realities." }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 1, "ans_text": "empirical" }, "bloom": null, "hl_context": "In the end , research is what makes the difference between facts and opinions . Facts are observable realities , and opinions are personal judgments , conclusions , or attitudes that may or may not be accurate . <hl> In the scientific community , facts can be established only using evidence collected through empirical research . <hl> The Process of Scientific Research Scientific knowledge is advanced through a process known as the scientific method . Basically , ideas ( in the form of theories and hypotheses ) are tested against the real world ( in the form of empirical observations ) , and those empirical observations lead to more ideas that are tested against the real world , and so on . In this sense , the scientific process is circular . The types of reasoning within the circle are called deductive and inductive . In deductive reasoning , ideas are tested against the empirical world ; in inductive reasoning , empirical observations lead to new ideas ( Figure 2.4 ) . These processes are inseparable , like inhaling and exhaling , but different research approaches place different emphasis on the deductive and inductive aspects . The goal of all scientists is to better understand the world around them . Psychologists focus their attention on understanding behavior , as well as the cognitive ( mental ) and physiological ( body ) processes that underlie behavior . In contrast to other methods that people use to understand the behavior of others , such as intuition and personal experience , the hallmark of scientific research is that there is evidence to support a claim . <hl> Scientific knowledge is empirical : It is grounded in objective , tangible evidence that can be observed time and time again , regardless of who is observing . <hl> While behavior is observable , the mind is not . If someone is crying , we can see behavior . However , the reason for the behavior is more difficult to determine . Is the person crying due to being sad , in pain , or happy ? Sometimes we can learn the reason for someone ’ s behavior by simply asking a question , like “ Why are you crying ? ” However , there are situations in which an individual is either uncomfortable or unwilling to answer the question honestly , or is incapable of answering . For example , infants would not be able to explain why they are crying . In such circumstances , the psychologist must be creative in finding ways to better understand behavior . This chapter explores how scientific knowledge is generated , and how important that knowledge is in forming decisions in our personal lives and in the public domain . Use of Research Information Trying to determine which theories are and are not accepted by the scientific community can be difficult , especially in an area of research as broad as psychology . More than ever before , we have an incredible amount of information at our fingertips , and a simple internet search on any given research topic might result in a number of contradictory studies . In these cases , we are witnessing the scientific community going through the process of reaching a consensus , and it could be quite some time before a consensus emerges . For example , the hypothesized link between exposure to media violence and subsequent aggression has been debated in the scientific community for roughly 60 years . Even today , we will find detractors , but a consensus is building . Several professional organizations view media violence exposure as a risk factor for actual violence , including the American Medical Association , the American Psychiatric Association , and the American Psychological Association ( American Academy of Pediatrics , American Academy of Child & Adolescent Psychiatry , American Psychological Association , American Medical Association , American Academy of Family Physicians , American Psychiatric Association , 2000 ) .", "hl_sentences": "In the scientific community , facts can be established only using evidence collected through empirical research . Scientific knowledge is empirical : It is grounded in objective , tangible evidence that can be observed time and time again , regardless of who is observing .", "question": { "cloze_format": "Scientific knowledge is ________.", "normal_format": "Which of the following is correct about scientific knowledge?", "question_choices": [ "intuitive", "empirical", "permanent", "subjective" ], "question_id": "fs-idp12843936", "question_text": "Scientific knowledge is ________." }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 3, "ans_text": "were not testable" }, "bloom": null, "hl_context": "<hl> A scientific hypothesis is also falsifiable , or capable of being shown to be incorrect . <hl> Recall from the introductory chapter that Sigmund Freud had lots of interesting ideas to explain various human behaviors ( Figure 2.6 ) . <hl> However , a major criticism of Freud ’ s theories is that many of his ideas are not falsifiable ; for example , it is impossible to imagine empirical observations that would disprove the existence of the id , the ego , and the superego — the three elements of personality described in Freud ’ s theories . <hl> Despite this , Freud ’ s theories are widely taught in introductory psychology texts because of their historical significance for personality psychology and psychotherapy , and these remain the root of all modern forms of therapy .", "hl_sentences": "A scientific hypothesis is also falsifiable , or capable of being shown to be incorrect . However , a major criticism of Freud ’ s theories is that many of his ideas are not falsifiable ; for example , it is impossible to imagine empirical observations that would disprove the existence of the id , the ego , and the superego — the three elements of personality described in Freud ’ s theories .", "question": { "cloze_format": "A major criticism of Freud’s early theories involves the fact that his theories ________.", "normal_format": "What was a major criticism of Freud’s early theories that involves his theories?", "question_choices": [ "were too limited in scope", "were too outrageous", "were too broad", "were not testable" ], "question_id": "fs-idp4710624", "question_text": "A major criticism of Freud’s early theories involves the fact that his theories ________." }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 2, "ans_text": "naturalistic observation" }, "bloom": null, "hl_context": "<hl> The greatest benefit of naturalistic observation is the validity , or accuracy , of information collected unobtrusively in a natural setting . <hl> Having individuals behave as they normally would in a given situation means that we have a higher degree of ecological validity , or realism , than we might achieve with other research approaches . Therefore , our ability to generalize the findings of the research to real-world situations is enhanced . If done correctly , we need not worry about people or animals modifying their behavior simply because they are being observed . Sometimes , people may assume that reality programs give us a glimpse into authentic human behavior . However , the principle of inconspicuous observation is violated as reality stars are followed by camera crews and are interviewed on camera for personal confessionals . Given that environment , we must doubt how natural and realistic their behaviors are . <hl> It should be pointed out that naturalistic observation is not limited to research involving humans . <hl> <hl> Indeed , some of the best-known examples of naturalistic observation involve researchers going into the field to observe various kinds of animals in their own environments . <hl> As with human studies , the researchers maintain their distance and avoid interfering with the animal subjects so as not to influence their natural behaviors . Scientists have used this technique to study social hierarchies and interactions among animals ranging from ground squirrels to gorillas . The information provided by these studies is invaluable in understanding how those animals organize socially and communicate with one another . The anthropologist Jane Goodall , for example , spent nearly five decades observing the behavior of chimpanzees in Africa ( Figure 2.8 ) . As an illustration of the types of concerns that a researcher might encounter in naturalistic observation , some scientists criticized Goodall for giving the chimps names instead of referring to them by numbers — using names was thought to undermine the emotional detachment required for the objectivity of the study ( McKie , 2010 ) . Suppose we send a classmate into the restroom to actually watch whether everyone washes their hands after using the restroom . Will our observer blend into the restroom environment by wearing a white lab coat , sitting with a clipboard , and staring at the sinks ? We want our researcher to be inconspicuous — perhaps standing at one of the sinks pretending to put in contact lenses while secretly recording the relevant information . <hl> This type of observational study is called naturalistic observation : observing behavior in its natural setting . <hl> To better understand peer exclusion , Suzanne Fanger collaborated with colleagues at the University of Texas to observe the behavior of preschool children on a playground . How did the observers remain inconspicuous over the duration of the study ? They equipped a few of the children with wireless microphones ( which the children quickly forgot about ) and observed while taking notes from a distance . Also , the children in that particular preschool ( a “ laboratory preschool ” ) were accustomed to having observers on the playground ( Fanger , Frankel , & Hazen , 2012 ) .", "hl_sentences": "The greatest benefit of naturalistic observation is the validity , or accuracy , of information collected unobtrusively in a natural setting . It should be pointed out that naturalistic observation is not limited to research involving humans . Indeed , some of the best-known examples of naturalistic observation involve researchers going into the field to observe various kinds of animals in their own environments . This type of observational study is called naturalistic observation : observing behavior in its natural setting .", "question": { "cloze_format": "________ involves observing behavior in individuals in their natural environments.", "normal_format": "What involves observing behavior in individuals in their natural environments?", "question_choices": [ "archival research", "case study", "naturalistic observation", "survey" ], "question_id": "fs-idm28267056", "question_text": "________ involves observing behavior in individuals in their natural environments." }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 2, "ans_text": "the inability to generalize the findings from this approach to the larger population" }, "bloom": null, "hl_context": "There is both strength and weakness of the survey in comparison to case studies . By using surveys , we can collect information from a larger sample of people . A larger sample is better able to reflect the actual diversity of the population , thus allowing better generalizability . Therefore , if our sample is sufficiently large and diverse , we can assume that the data we collect from the survey can be generalized to the larger population with more certainty than the information collected through a case study . <hl> However , given the greater number of people involved , we are not able to collect the same depth of information on each person that would be collected in a case study . <hl> If clinical or case studies provide so much information , why are they not more frequent among researchers ? As it turns out , the major benefit of this particular approach is also a weakness . As mentioned earlier , this approach is often used when studying individuals who are interesting to researchers because they have a rare characteristic . Therefore , the individuals who serve as the focus of case studies are not like most other people . <hl> If scientists ultimately want to explain all behavior , focusing attention on such a special group of people can make it difficult to generalize any observations to the larger population as a whole . <hl> Generalizing refers to the ability to apply the findings of a particular research project to larger segments of society . Again , case studies provide enormous amounts of information , but since the cases are so specific , the potential to apply what ’ s learned to the average person may be very limited .", "hl_sentences": "However , given the greater number of people involved , we are not able to collect the same depth of information on each person that would be collected in a case study . If scientists ultimately want to explain all behavior , focusing attention on such a special group of people can make it difficult to generalize any observations to the larger population as a whole .", "question": { "cloze_format": "The major limitation of case studies is ________.", "normal_format": "What is the major limitation of case studies?", "question_choices": [ "the superficial nature of the information collected in this approach", "the lack of control that the researcher has in this approach", "the inability to generalize the findings from this approach to the larger population", "the absence of inter-rater reliability" ], "question_id": "fs-idm15501216", "question_text": "The major limitation of case studies is ________." }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 0, "ans_text": "the honesty of the data that is collected in a realistic setting" }, "bloom": null, "hl_context": "<hl> The greatest benefit of naturalistic observation is the validity , or accuracy , of information collected unobtrusively in a natural setting . <hl> Having individuals behave as they normally would in a given situation means that we have a higher degree of ecological validity , or realism , than we might achieve with other research approaches . Therefore , our ability to generalize the findings of the research to real-world situations is enhanced . If done correctly , we need not worry about people or animals modifying their behavior simply because they are being observed . Sometimes , people may assume that reality programs give us a glimpse into authentic human behavior . However , the principle of inconspicuous observation is violated as reality stars are followed by camera crews and are interviewed on camera for personal confessionals . Given that environment , we must doubt how natural and realistic their behaviors are .", "hl_sentences": "The greatest benefit of naturalistic observation is the validity , or accuracy , of information collected unobtrusively in a natural setting .", "question": { "cloze_format": "The benefit of naturalistic observation studies is ________.", "normal_format": "What is the benefit of naturalistic observation studies?", "question_choices": [ "the honesty of the data that is collected in a realistic setting", "how quick and easy these studies are to perform", "the researcher’s capacity to make sure that data is collected as efficiently as possible", "the ability to determine cause and effect in this particular approach" ], "question_id": "fs-idm4568128", "question_text": "The benefit of naturalistic observation studies is ________." }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 3, "ans_text": "archival research" }, "bloom": null, "hl_context": "In comparing archival research to other research methods , there are several important distinctions . For one , the researcher employing archival research never directly interacts with research participants . Therefore , the investment of time and money to collect data is considerably less with archival research . Additionally , researchers have no control over what information was originally collected . <hl> Therefore , research questions have to be tailored so they can be answered within the structure of the existing data sets . <hl> There is also no guarantee of consistency between the records from one source to another , which might make comparing and contrasting different data sets problematic . Some researchers gain access to large amounts of data without interacting with a single research participant . <hl> Instead , they use existing records to answer various research questions . <hl> <hl> This type of research approach is known as archival research . <hl> <hl> Archival research relies on looking at past records or data sets to look for interesting patterns or relationships . <hl> Each of these research methods has unique strengths and weaknesses , and each method may only be appropriate for certain types of research questions . For example , studies that rely primarily on observation produce incredible amounts of information , but the ability to apply this information to the larger population is somewhat limited because of small sample sizes . Survey research , on the other hand , allows researchers to easily collect data from relatively large samples . While this allows for results to be generalized to the larger population more easily , the information that can be collected on any given survey is somewhat limited and subject to problems associated with any type of self-reported data . <hl> Some researchers conduct archival research by using existing records . <hl> While this can be a fairly inexpensive way to collect data that can provide insight into a number of research questions , researchers using this approach have no control on how or what kind of data was collected . All of the methods described thus far are correlational in nature . This means that researchers can speak to important relationships that might exist between two or more variables of interest . However , correlational data cannot be used to make claims about cause-and-effect relationships .", "hl_sentences": "Therefore , research questions have to be tailored so they can be answered within the structure of the existing data sets . Instead , they use existing records to answer various research questions . This type of research approach is known as archival research . Archival research relies on looking at past records or data sets to look for interesting patterns or relationships . Some researchers conduct archival research by using existing records .", "question": { "cloze_format": "Using existing records to try to answer a research question is known as ________.", "normal_format": "What is using existing records to try to answer a research question known as?", "question_choices": [ "naturalistic observation", "survey research", "longitudinal research", "archival research" ], "question_id": "fs-idm34278992", "question_text": "Using existing records to try to answer a research question is known as ________." }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 1, "ans_text": "longitudinal research" }, "bloom": null, "hl_context": "<hl> As with any research strategy , longitudinal research is not without limitations . <hl> <hl> For one , these studies require an incredible time investment by the researcher and research participants . <hl> Given that some longitudinal studies take years , if not decades , to complete , the results will not be known for a considerable period of time . In addition to the time demands , these studies also require a substantial financial investment . Many researchers are unable to commit the resources necessary to see a longitudinal project through to the end . Sometimes we want to see how people change over time , as in studies of human development and lifespan . <hl> When we test the same group of individuals repeatedly over an extended period of time , we are conducting longitudinal research . <hl> <hl> Longitudinal research is a research design in which data-gathering is administered repeatedly over an extended period of time . <hl> For example , we may survey a group of individuals about their dietary habits at age 20 , retest them a decade later at age 30 , and then again at age 40 .", "hl_sentences": "As with any research strategy , longitudinal research is not without limitations . For one , these studies require an incredible time investment by the researcher and research participants . When we test the same group of individuals repeatedly over an extended period of time , we are conducting longitudinal research . Longitudinal research is a research design in which data-gathering is administered repeatedly over an extended period of time .", "question": { "cloze_format": "________ involves following a group of research participants for an extended period of time.", "normal_format": "Which method involves following a group of research participants for an extended period of time?", "question_choices": [ "archival research", "longitudinal research", "naturalistic observation", "cross-sectional research" ], "question_id": "fs-idp899008", "question_text": "________ involves following a group of research participants for an extended period of time." }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 3, "ans_text": "survey" }, "bloom": null, "hl_context": "Often , psychologists develop surveys as a means of gathering data . <hl> Surveys are lists of questions to be answered by research participants , and can be delivered as paper-and-pencil questionnaires , administered electronically , or conducted verbally ( Figure 2.9 ) . <hl> Generally , the survey itself can be completed in a short time , and the ease of administering a survey makes it easy to collect data from a large number of people .", "hl_sentences": "Surveys are lists of questions to be answered by research participants , and can be delivered as paper-and-pencil questionnaires , administered electronically , or conducted verbally ( Figure 2.9 ) .", "question": { "cloze_format": "A(n) ________ is a list of questions developed by a researcher that can be administered in paper form.", "normal_format": "What is a list of questions developed by a researcher that can be administered in paper form?", "question_choices": [ "archive", "case Study", "naturalistic observation", "survey" ], "question_id": "fs-idm124782544", "question_text": "A(n) ________ is a list of questions developed by a researcher that can be administered in paper form." }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 2, "ans_text": "attrition" }, "bloom": null, "hl_context": "Research participants must also be willing to continue their participation for an extended period of time , and this can be problematic . People move , get married and take new names , get ill , and eventually die . Even without significant life changes , some people may simply choose to discontinue their participation in the project . <hl> As a result , the attrition rates , or reduction in the number of research participants due to dropouts , in longitudinal studies are quite high and increases over the course of a project . <hl> For this reason , researchers using this approach typically recruit many participants fully expecting that a substantial number will drop out before the end . As the study progresses , they continually check whether the sample still represents the larger population , and make adjustments as necessary . 2.3 Analyzing Findings Learning Objectives By the end of this section , you will be able to :", "hl_sentences": "As a result , the attrition rates , or reduction in the number of research participants due to dropouts , in longitudinal studies are quite high and increases over the course of a project .", "question": { "cloze_format": "Longitudinal research is complicated by high rates of ________.", "normal_format": "High rates of what is complicate the longitudinal research? ", "question_choices": [ "deception", "observation", "attrition", "generalization" ], "question_id": "fs-idm30197456", "question_text": "Longitudinal research is complicated by high rates of ________." }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 3, "ans_text": "As height increases, typically weight increases." }, "bloom": null, "hl_context": "<hl> The example of ice cream and crime rates is a positive correlation because both variables increase when temperatures are warmer . <hl> <hl> Other examples of positive correlations are the relationship between an individual ’ s height and weight or the relationship between a person ’ s age and number of wrinkles . <hl> One might expect a negative correlation to exist between someone ’ s tiredness during the day and the number of hours they slept the previous night : the amount of sleep decreases as the feelings of tiredness increase . In a real-world example of negative correlation , student researchers at the University of Minnesota found a weak negative correlation ( r = -0.29 ) between the average number of days per week that students got fewer than 5 hours of sleep and their GPA ( Lowry , Dean , & Manders , 2010 ) . Keep in mind that a negative correlation is not the same as no correlation . For example , we would probably find no correlation between hours of sleep and shoe size . The sign — positive or negative — of the correlation coefficient indicates the direction of the relationship ( Figure 2.12 ) . <hl> A positive correlation means that the variables move in the same direction . <hl> <hl> Put another way , it means that as one variable increases so does the other , and conversely , when one variable decreases so does the other . <hl> A negative correlation means that the variables move in opposite directions . If two variables are negatively correlated , a decrease in one variable is associated with an increase in the other and vice versa .", "hl_sentences": "The example of ice cream and crime rates is a positive correlation because both variables increase when temperatures are warmer . Other examples of positive correlations are the relationship between an individual ’ s height and weight or the relationship between a person ’ s age and number of wrinkles . A positive correlation means that the variables move in the same direction . Put another way , it means that as one variable increases so does the other , and conversely , when one variable decreases so does the other .", "question": { "cloze_format": "Height and weight are positively correlated what means that ___.", "normal_format": "Height and weight are positively correlated. What does this mean?", "question_choices": [ "There is no relationship between height and weight. ", "Usually, the taller someone is, the thinner they are. ", "Usually, the shorter someone is, the heavier they are.", "As height increases, typically weight increases." ], "question_id": "fs-idm28997136", "question_text": "Height and weight are positively correlated. This means that:" }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 0, "ans_text": "-.90" }, "bloom": null, "hl_context": "The number portion of the correlation coefficient indicates the strength of the relationship . <hl> The closer the number is to 1 ( be it negative or positive ) , the more strongly related the variables are , and the more predictable changes in one variable will be as the other variable changes . <hl> <hl> The closer the number is to zero , the weaker the relationship , and the less predictable the relationships between the variables becomes . <hl> <hl> For instance , a correlation coefficient of 0.9 indicates a far stronger relationship than a correlation coefficient of 0.3 . <hl> If the variables are not related to one another at all , the correlation coefficient is 0 . The example above about ice cream and crime is an example of two variables that we might expect to have no relationship to each other .", "hl_sentences": "The closer the number is to 1 ( be it negative or positive ) , the more strongly related the variables are , and the more predictable changes in one variable will be as the other variable changes . The closer the number is to zero , the weaker the relationship , and the less predictable the relationships between the variables becomes . For instance , a correlation coefficient of 0.9 indicates a far stronger relationship than a correlation coefficient of 0.3 .", "question": { "cloze_format": "___ indicates the strongest relationship between two variables.", "normal_format": "Which of the following correlation coefficients indicates the strongest relationship between two variables?", "question_choices": [ "-.90", "-.50", "+.80", "+.25" ], "question_id": "fs-idm46475056", "question_text": "Which of the following correlation coefficients indicates the strongest relationship between two variables?" }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 0, "ans_text": "it is closest to 0" }, "bloom": null, "hl_context": "The number portion of the correlation coefficient indicates the strength of the relationship . The closer the number is to 1 ( be it negative or positive ) , the more strongly related the variables are , and the more predictable changes in one variable will be as the other variable changes . <hl> The closer the number is to zero , the weaker the relationship , and the less predictable the relationships between the variables becomes . <hl> <hl> For instance , a correlation coefficient of 0.9 indicates a far stronger relationship than a correlation coefficient of 0.3 . <hl> <hl> If the variables are not related to one another at all , the correlation coefficient is 0 . <hl> The example above about ice cream and crime is an example of two variables that we might expect to have no relationship to each other .", "hl_sentences": "The closer the number is to zero , the weaker the relationship , and the less predictable the relationships between the variables becomes . For instance , a correlation coefficient of 0.9 indicates a far stronger relationship than a correlation coefficient of 0.3 . If the variables are not related to one another at all , the correlation coefficient is 0 .", "question": { "cloze_format": "The correlation coefficient indicates the weakest relationship when ________.", "normal_format": "When does the correlation coefficient indicate the weakest relationship? ", "question_choices": [ "it is closest to 0", "it is closest to -1", "it is positive", "it is negative" ], "question_id": "fs-idm32547936", "question_text": "The correlation coefficient indicates the weakest relationship when ________." }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 3, "ans_text": "random sampling" }, "bloom": null, "hl_context": "Now that we have a sample , the next step of the experimental process is to split the participants into experimental and control groups through random assignment . <hl> With random assignment , all participants have an equal chance of being assigned to either group . <hl> There is statistical software that will randomly assign each of the fourth graders in the sample to either the experimental or the control group . Our hypothetical experiment involves children , and we must first generate a sample of child participants . Samples are used because populations are usually too large to reasonably involve every member in our particular experiment ( Figure 2.18 ) . If possible , we should use a random sample ( there are other types of samples , but for the purposes of this chapter , we will focus on random samples ) . <hl> A random sample is a subset of a larger population in which every member of the population has an equal chance of being selected . <hl> Random samples are preferred because if the sample is large enough we can be reasonably sure that the participating individuals are representative of the larger population . This means that the percentages of characteristics in the sample — sex , ethnicity , socioeconomic level , and any other characteristics that might affect the results — are close to those percentages in the larger population .", "hl_sentences": "With random assignment , all participants have an equal chance of being assigned to either group . A random sample is a subset of a larger population in which every member of the population has an equal chance of being selected .", "question": { "cloze_format": "________ means that everyone in the population has the same likelihood of being asked to participate in the study.", "normal_format": "What means that everyone in the population has the same likelihood of being asked to participate in the study?", "question_choices": [ "operationalizing", "placebo effect", "random assignment", "random sampling" ], "question_id": "fs-idm46864688", "question_text": "________ means that everyone in the population has the same likelihood of being asked to participate in the study." }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 1, "ans_text": "independent variable; dependent variable" }, "bloom": null, "hl_context": "While experiments allow scientists to make cause-and-effect claims , they are not without problems . <hl> True experiments require the experimenter to manipulate an independent variable , and that can complicate many questions that psychologists might want to address . <hl> For instance , imagine that you want to know what effect sex ( the independent variable ) has on spatial memory ( the dependent variable ) . Although you can certainly look for differences between males and females on a task that taps into spatial memory , you cannot directly control a person ’ s sex . We categorize this type of research approach as quasi-experimental and recognize that we cannot make cause-and-effect claims in these circumstances . In a research experiment , we strive to study whether changes in one thing cause changes in another . To achieve this , we must pay attention to two important variables , or things that can be changed , in any experimental study : the independent variable and the dependent variable . <hl> An independent variable is manipulated or controlled by the experimenter . <hl> In a well-designed experimental study , the independent variable is the only important difference between the experimental and control groups . In our example of how violent television programs affect children ’ s display of violent behavior , the independent variable is the type of program — violent or nonviolent — viewed by participants in the study ( Figure 2.17 ) . <hl> A dependent variable is what the researcher measures to see how much effect the independent variable had . <hl> In our example , the dependent variable is the number of violent acts displayed by the experimental participants .", "hl_sentences": "True experiments require the experimenter to manipulate an independent variable , and that can complicate many questions that psychologists might want to address . An independent variable is manipulated or controlled by the experimenter . A dependent variable is what the researcher measures to see how much effect the independent variable had .", "question": { "cloze_format": "The ________ is controlled by the experimenter, while the ________ represents the information collected and statistically analyzed by the experimenter.", "normal_format": "What is controlled by the experimenter and what represents the information collected and statistically analyzed by the experimenter, respectively? ", "question_choices": [ "dependent variable; independent variable", "independent variable; dependent variable", "placebo effect; experimenter bias", "experiment bias; placebo effect" ], "question_id": "fs-idm44434400", "question_text": "The ________ is controlled by the experimenter, while the ________ represents the information collected and statistically analyzed by the experimenter." }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 2, "ans_text": "operationalize" }, "bloom": null, "hl_context": "<hl> We also need to precisely define , or operationalize , what is considered violent and nonviolent . <hl> <hl> An operational definition is a description of how we will measure our variables , and it is important in allowing others understand exactly how and what a researcher measures in a particular experiment . <hl> In operationalizing violent behavior , we might choose to count only physical acts like kicking or punching as instances of this behavior , or we also may choose to include angry verbal exchanges . <hl> Whatever we determine , it is important that we operationalize violent behavior in such a way that anyone who hears about our study for the first time knows exactly what we mean by violence . <hl> This aids peoples ’ ability to interpret our data as well as their capacity to repeat our experiment should they choose to do so .", "hl_sentences": "We also need to precisely define , or operationalize , what is considered violent and nonviolent . An operational definition is a description of how we will measure our variables , and it is important in allowing others understand exactly how and what a researcher measures in a particular experiment . Whatever we determine , it is important that we operationalize violent behavior in such a way that anyone who hears about our study for the first time knows exactly what we mean by violence .", "question": { "cloze_format": "Researchers must ________ important concepts in their studies so others would have a clear understanding of exactly how those concepts were defined.", "normal_format": "How must researchers examine important concepts in their studies so others would have a clear understanding of exactly how those concepts were defined?", "question_choices": [ "randomly assign", "randomly select", "operationalize", "generalize" ], "question_id": "fs-idm38751904", "question_text": "Researchers must ________ important concepts in their studies so others would have a clear understanding of exactly how those concepts were defined." }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 3, "ans_text": "placebo" }, "bloom": null, "hl_context": "In a double-blind study , both the researchers and the participants are blind to group assignments . Why would a researcher want to run a study where no one knows who is in which group ? Because by doing so , we can control for both experimenter and participant expectations . If you are familiar with the phrase placebo effect , you already have some idea as to why this is an important consideration . <hl> The placebo effect occurs when people's expectations or beliefs influence or determine their experience in a given situation . <hl> <hl> In other words , simply expecting something to happen can actually make it happen . <hl>", "hl_sentences": "The placebo effect occurs when people's expectations or beliefs influence or determine their experience in a given situation . In other words , simply expecting something to happen can actually make it happen .", "question": { "cloze_format": "Sometimes, researchers will administer a(n) ________ to participants in the control group to control for the effects that participant expectation might have on the experiment.", "normal_format": "What will researchers sometimes administer to participants in the control group to control for the effects that participant expectation might have on the experiment?", "question_choices": [ "dependent variable", "independent variable", "statistical analysis", "placebo" ], "question_id": "fs-idm38758640", "question_text": "Sometimes, researchers will administer a(n) ________ to participants in the control group to control for the effects that participant expectation might have on the experiment." }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 1, "ans_text": "IACUC; IRB" }, "bloom": null, "hl_context": "<hl> Whereas IRBs review research proposals that involve human participants , animal experimental proposals are reviewed by an Institutional Animal Care and Use Committee ( IACUC ) . <hl> An IACUC consists of institutional administrators , scientists , veterinarians , and community members . This committee is charged with ensuring that all experimental proposals require the humane treatment of animal research subjects . It also conducts semi-annual inspections of all animal facilities to ensure that the research protocols are being followed . No animal research project can proceed without the committee ’ s approval .", "hl_sentences": "Whereas IRBs review research proposals that involve human participants , animal experimental proposals are reviewed by an Institutional Animal Care and Use Committee ( IACUC ) .", "question": { "cloze_format": "________ is to animal research as ________ is to human research.", "normal_format": "What is animal research is to as what is human research to?", "question_choices": [ "informed consent; deception", "IACUC; IRB", "IRB; IACUC", "deception; debriefing" ], "question_id": "fs-idm232832", "question_text": "________ is to animal research as ________ is to human research." }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 1, "ans_text": "deception" }, "bloom": null, "hl_context": "Visit this website to see an example of a consent form . <hl> While the informed consent form should be as honest as possible in describing exactly what participants will be doing , sometimes deception is necessary to prevent participants ’ knowledge of the exact research question from affecting the results of the study . <hl> Deception involves purposely misleading experiment participants in order to maintain the integrity of the experiment , but not to the point where the deception could be considered harmful . For example , if we are interested in how our opinion of someone is affected by their attire , we might use deception in describing the experiment to prevent that knowledge from affecting participants ’ responses . In cases where deception is involved , participants must receive a full debriefing upon conclusion of the study — complete , honest information about the purpose of the experiment , how the data collected will be used , the reasons why deception was necessary , and information about how to obtain additional information about the study .", "hl_sentences": "While the informed consent form should be as honest as possible in describing exactly what participants will be doing , sometimes deception is necessary to prevent participants ’ knowledge of the exact research question from affecting the results of the study .", "question": { "cloze_format": "Researchers might use ________ when providing participants with the full details of the experiment could skew their responses.", "normal_format": "What researchers might use when providing participants with the full details of the experiment could skew their responses?", "question_choices": [ "informed consent", "deception", "ethics", "debriefing" ], "question_id": "fs-idm60364544", "question_text": "Researchers might use ________ when providing participants with the full details of the experiment could skew their responses." }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 2, "ans_text": "voluntary" }, "bloom": null, "hl_context": "An institution ’ s IRB requires several components in any experiment it approves . <hl> For one , each participant must sign an informed consent form before they can participate in the experiment . <hl> An informed consent form provides a written description of what participants can expect during the experiment , including potential risks and implications of the research . <hl> It also lets participants know that their involvement is completely voluntary and can be discontinued without penalty at any time . <hl> Furthermore , the informed consent guarantees that any data collected in the experiment will remain completely confidential . In cases where research participants are under the age of 18 , the parents or legal guardians are required to sign the informed consent form .", "hl_sentences": "For one , each participant must sign an informed consent form before they can participate in the experiment . It also lets participants know that their involvement is completely voluntary and can be discontinued without penalty at any time .", "question": { "cloze_format": "A person’s participation in a research project must be ________.", "normal_format": "What must be a person’s participation in a research project?", "question_choices": [ "random", "rewarded", "voluntary", "public" ], "question_id": "fs-idm4993776", "question_text": "A person’s participation in a research project must be ________." }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 0, "ans_text": "informed consent" }, "bloom": null, "hl_context": "An institution ’ s IRB requires several components in any experiment it approves . <hl> For one , each participant must sign an informed consent form before they can participate in the experiment . <hl> An informed consent form provides a written description of what participants can expect during the experiment , including potential risks and implications of the research . It also lets participants know that their involvement is completely voluntary and can be discontinued without penalty at any time . Furthermore , the informed consent guarantees that any data collected in the experiment will remain completely confidential . In cases where research participants are under the age of 18 , the parents or legal guardians are required to sign the informed consent form .", "hl_sentences": "For one , each participant must sign an informed consent form before they can participate in the experiment .", "question": { "cloze_format": "Before participating in an experiment, individuals should read and sign the ________ form.", "normal_format": "Before participating in an experiment, individuals should read and sign which form?", "question_choices": [ "informed consent", "debriefing", "IRB", "ethics" ], "question_id": "fs-idm49222928", "question_text": "Before participating in an experiment, individuals should read and sign the ________ form." }, "references_are_paraphrase": null } ]
2
2.1 Why Is Research Important? Learning Objectives By the end of this section, you will be able to: Explain how scientific research addresses questions about behavior Discuss how scientific research guides public policy Appreciate how scientific research can be important in making personal decisions Scientific research is a critical tool for successfully navigating our complex world. Without it, we would be forced to rely solely on intuition, other people’s authority, and blind luck. While many of us feel confident in our abilities to decipher and interact with the world around us, history is filled with examples of how very wrong we can be when we fail to recognize the need for evidence in supporting claims. At various times in history, we would have been certain that the sun revolved around a flat earth, that the earth’s continents did not move, and that mental illness was caused by possession ( Figure 2.2 ). It is through systematic scientific research that we divest ourselves of our preconceived notions and superstitions and gain an objective understanding of ourselves and our world. The goal of all scientists is to better understand the world around them. Psychologists focus their attention on understanding behavior, as well as the cognitive (mental) and physiological (body) processes that underlie behavior. In contrast to other methods that people use to understand the behavior of others, such as intuition and personal experience, the hallmark of scientific research is that there is evidence to support a claim. Scientific knowledge is empirical : It is grounded in objective, tangible evidence that can be observed time and time again, regardless of who is observing. While behavior is observable, the mind is not. If someone is crying, we can see behavior. However, the reason for the behavior is more difficult to determine. Is the person crying due to being sad, in pain, or happy? Sometimes we can learn the reason for someone’s behavior by simply asking a question, like “Why are you crying?” However, there are situations in which an individual is either uncomfortable or unwilling to answer the question honestly, or is incapable of answering. For example, infants would not be able to explain why they are crying. In such circumstances, the psychologist must be creative in finding ways to better understand behavior. This chapter explores how scientific knowledge is generated, and how important that knowledge is in forming decisions in our personal lives and in the public domain. Use of Research Information Trying to determine which theories are and are not accepted by the scientific community can be difficult, especially in an area of research as broad as psychology. More than ever before, we have an incredible amount of information at our fingertips, and a simple internet search on any given research topic might result in a number of contradictory studies. In these cases, we are witnessing the scientific community going through the process of reaching a consensus, and it could be quite some time before a consensus emerges. For example, the hypothesized link between exposure to media violence and subsequent aggression has been debated in the scientific community for roughly 60 years. Even today, we will find detractors, but a consensus is building. Several professional organizations view media violence exposure as a risk factor for actual violence, including the American Medical Association, the American Psychiatric Association, and the American Psychological Association (American Academy of Pediatrics, American Academy of Child & Adolescent Psychiatry, American Psychological Association, American Medical Association, American Academy of Family Physicians, American Psychiatric Association, 2000). In the meantime, we should strive to think critically about the information we encounter by exercising a degree of healthy skepticism. When someone makes a claim, we should examine the claim from a number of different perspectives: what is the expertise of the person making the claim, what might they gain if the claim is valid, does the claim seem justified given the evidence, and what do other researchers think of the claim? This is especially important when we consider how much information in advertising campaigns and on the internet claims to be based on “scientific evidence” when in actuality it is a belief or perspective of just a few individuals trying to sell a product or draw attention to their perspectives. We should be informed consumers of the information made available to us because decisions based on this information have significant consequences. One such consequence can be seen in politics and public policy. Imagine that you have been elected as the governor of your state. One of your responsibilities is to manage the state budget and determine how to best spend your constituents’ tax dollars. As the new governor, you need to decide whether to continue funding the D.A.R.E. (Drug Abuse Resistance Education) program in public schools ( Figure 2.3 ). This program typically involves police officers coming into the classroom to educate students about the dangers of becoming involved with alcohol and other drugs. According to the D.A.R.E. website (www.dare.org), this program has been very popular since its inception in 1983, and it is currently operating in 75% of school districts in the United States and in more than 40 countries worldwide. Sounds like an easy decision, right? However, on closer review, you discover that the vast majority of research into this program consistently suggests that participation has little, if any, effect on whether or not someone uses alcohol or other drugs (Clayton, Cattarello, & Johnstone, 1996; Ennett, Tobler, Ringwalt, & Flewelling, 1994; Lynam et al., 1999; Ringwalt, Ennett, & Holt, 1991). If you are committed to being a good steward of taxpayer money, will you fund this particular program, or will you try to find other programs that research has consistently demonstrated to be effective? Link to Learning Watch this news report to learn more about some of the controversial issues surrounding the D.A.R.E. program. Ultimately, it is not just politicians who can benefit from using research in guiding their decisions. We all might look to research from time to time when making decisions in our lives. Imagine you just found out that a close friend has breast cancer or that one of your young relatives has recently been diagnosed with autism. In either case, you want to know which treatment options are most successful with the fewest side effects. How would you find that out? You would probably talk with your doctor and personally review the research that has been done on various treatment options—always with a critical eye to ensure that you are as informed as possible. In the end, research is what makes the difference between facts and opinions. Facts are observable realities, and opinions are personal judgments, conclusions, or attitudes that may or may not be accurate. In the scientific community, facts can be established only using evidence collected through empirical research. The Process of Scientific Research Scientific knowledge is advanced through a process known as the scientific method . Basically, ideas (in the form of theories and hypotheses) are tested against the real world (in the form of empirical observations), and those empirical observations lead to more ideas that are tested against the real world, and so on. In this sense, the scientific process is circular. The types of reasoning within the circle are called deductive and inductive. In deductive reasoning , ideas are tested against the empirical world; in inductive reasoning , empirical observations lead to new ideas ( Figure 2.4 ). These processes are inseparable, like inhaling and exhaling, but different research approaches place different emphasis on the deductive and inductive aspects. In the scientific context, deductive reasoning begins with a generalization—one hypothesis—that is then used to reach logical conclusions about the real world. If the hypothesis is correct, then the logical conclusions reached through deductive reasoning should also be correct. A deductive reasoning argument might go something like this: All living things require energy to survive (this would be your hypothesis). Ducks are living things. Therefore, ducks require energy to survive (logical conclusion). In this example, the hypothesis is correct; therefore, the conclusion is correct as well. Sometimes, however, an incorrect hypothesis may lead to a logical but incorrect conclusion. Consider this argument: all ducks are born with the ability to see. Quackers is a duck. Therefore, Quackers was born with the ability to see. Scientists use deductive reasoning to empirically test their hypotheses. Returning to the example of the ducks, researchers might design a study to test the hypothesis that if all living things require energy to survive, then ducks will be found to require energy to survive. Deductive reasoning starts with a generalization that is tested against real-world observations; however, inductive reasoning moves in the opposite direction. Inductive reasoning uses empirical observations to construct broad generalizations. Unlike deductive reasoning, conclusions drawn from inductive reasoning may or may not be correct, regardless of the observations on which they are based. For instance, you may notice that your favorite fruits—apples, bananas, and oranges—all grow on trees; therefore, you assume that all fruit must grow on trees. This would be an example of inductive reasoning, and, clearly, the existence of strawberries, blueberries, and kiwi demonstrate that this generalization is not correct despite it being based on a number of direct observations. Scientists use inductive reasoning to formulate theories, which in turn generate hypotheses that are tested with deductive reasoning. In the end, science involves both deductive and inductive processes. For example, case studies, which you will read about in the next section, are heavily weighted on the side of empirical observations. Thus, case studies are closely associated with inductive processes as researchers gather massive amounts of observations and seek interesting patterns (new ideas) in the data. Experimental research, on the other hand, puts great emphasis on deductive reasoning. Link to Learning Play this “Deal Me In” interactive card game to practice using inductive reasoning. We’ve stated that theories and hypotheses are ideas, but what sort of ideas are they, exactly? A theory is a well-developed set of ideas that propose an explanation for observed phenomena. Theories are repeatedly checked against the world, but they tend to be too complex to be tested all at once; instead, researchers create hypotheses to test specific aspects of a theory. A hypothesis is a testable prediction about how the world will behave if our idea is correct, and it is often worded as an if-then statement (e.g., if I study all night, I will get a passing grade on the test). The hypothesis is extremely important because it bridges the gap between the realm of ideas and the real world. As specific hypotheses are tested, theories are modified and refined to reflect and incorporate the result of these tests Figure 2.5 . To see how this process works, let’s consider a specific theory and a hypothesis that might be generated from that theory. As you’ll learn in a later chapter, the James-Lange theory of emotion asserts that emotional experience relies on the physiological arousal associated with the emotional state. If you walked out of your home and discovered a very aggressive snake waiting on your doorstep, your heart would begin to race and your stomach churn. According to the James-Lange theory, these physiological changes would result in your feeling of fear. A hypothesis that could be derived from this theory might be that a person who is unaware of the physiological arousal that the sight of the snake elicits will not feel fear. A scientific hypothesis is also falsifiable , or capable of being shown to be incorrect. Recall from the introductory chapter that Sigmund Freud had lots of interesting ideas to explain various human behaviors ( Figure 2.6 ). However, a major criticism of Freud’s theories is that many of his ideas are not falsifiable; for example, it is impossible to imagine empirical observations that would disprove the existence of the id, the ego, and the superego—the three elements of personality described in Freud’s theories. Despite this, Freud’s theories are widely taught in introductory psychology texts because of their historical significance for personality psychology and psychotherapy, and these remain the root of all modern forms of therapy. In contrast, the James-Lange theory does generate falsifiable hypotheses, such as the one described above. Some individuals who suffer significant injuries to their spinal columns are unable to feel the bodily changes that often accompany emotional experiences. Therefore, we could test the hypothesis by determining how emotional experiences differ between individuals who have the ability to detect these changes in their physiological arousal and those who do not. In fact, this research has been conducted and while the emotional experiences of people deprived of an awareness of their physiological arousal may be less intense, they still experience emotion (Chwalisz, Diener, & Gallagher, 1988). Scientific research’s dependence on falsifiability allows for great confidence in the information that it produces. Typically, by the time information is accepted by the scientific community, it has been tested repeatedly. Link to Learning Visit this website to apply the scientific method and practice its steps by using them to solve a murder mystery, determine why a student is in trouble, and design an experiment to test house paint. 2.2 Approaches to Research Learning Objectives By the end of this section, you will be able to: Describe the different research methods used by psychologists Discuss the strengths and weaknesses of case studies, naturalistic observation, surveys, and archival research Compare longitudinal and cross-sectional approaches to research There are many research methods available to psychologists in their efforts to understand, describe, and explain behavior and the cognitive and biological processes that underlie it. Some methods rely on observational techniques. Other approaches involve interactions between the researcher and the individuals who are being studied—ranging from a series of simple questions to extensive, in-depth interviews—to well-controlled experiments. Each of these research methods has unique strengths and weaknesses, and each method may only be appropriate for certain types of research questions. For example, studies that rely primarily on observation produce incredible amounts of information, but the ability to apply this information to the larger population is somewhat limited because of small sample sizes. Survey research, on the other hand, allows researchers to easily collect data from relatively large samples. While this allows for results to be generalized to the larger population more easily, the information that can be collected on any given survey is somewhat limited and subject to problems associated with any type of self-reported data. Some researchers conduct archival research by using existing records. While this can be a fairly inexpensive way to collect data that can provide insight into a number of research questions, researchers using this approach have no control on how or what kind of data was collected. All of the methods described thus far are correlational in nature. This means that researchers can speak to important relationships that might exist between two or more variables of interest. However, correlational data cannot be used to make claims about cause-and-effect relationships. Correlational research can find a relationship between two variables, but the only way a researcher can claim that the relationship between the variables is cause and effect is to perform an experiment. In experimental research, which will be discussed later in this chapter, there is a tremendous amount of control over variables of interest. While this is a powerful approach, experiments are often conducted in very artificial settings. This calls into question the validity of experimental findings with regard to how they would apply in real-world settings. In addition, many of the questions that psychologists would like to answer cannot be pursued through experimental research because of ethical concerns. Clinical or Case Studies In 2011, the New York Times published a feature story on Krista and Tatiana Hogan, Canadian twin girls. These particular twins are unique because Krista and Tatiana are conjoined twins, connected at the head. There is evidence that the two girls are connected in a part of the brain called the thalamus, which is a major sensory relay center. Most incoming sensory information is sent through the thalamus before reaching higher regions of the cerebral cortex for processing. Link to Learning To learn more about Krista and Tatiana, watch this New York Times video about their lives. The implications of this potential connection mean that it might be possible for one twin to experience the sensations of the other twin. For instance, if Krista is watching a particularly funny television program, Tatiana might smile or laugh even if she is not watching the program. This particular possibility has piqued the interest of many neuroscientists who seek to understand how the brain uses sensory information. These twins represent an enormous resource in the study of the brain, and since their condition is very rare, it is likely that as long as their family agrees, scientists will follow these girls very closely throughout their lives to gain as much information as possible (Dominus, 2011). In observational research, scientists are conducting a clinical or case study when they focus on one person or just a few individuals. Indeed, some scientists spend their entire careers studying just 10–20 individuals. Why would they do this? Obviously, when they focus their attention on a very small number of people, they can gain a tremendous amount of insight into those cases. The richness of information that is collected in clinical or case studies is unmatched by any other single research method. This allows the researcher to have a very deep understanding of the individuals and the particular phenomenon being studied. If clinical or case studies provide so much information, why are they not more frequent among researchers? As it turns out, the major benefit of this particular approach is also a weakness. As mentioned earlier, this approach is often used when studying individuals who are interesting to researchers because they have a rare characteristic. Therefore, the individuals who serve as the focus of case studies are not like most other people. If scientists ultimately want to explain all behavior, focusing attention on such a special group of people can make it difficult to generalize any observations to the larger population as a whole. Generalizing refers to the ability to apply the findings of a particular research project to larger segments of society. Again, case studies provide enormous amounts of information, but since the cases are so specific, the potential to apply what’s learned to the average person may be very limited. Naturalistic Observation If you want to understand how behavior occurs, one of the best ways to gain information is to simply observe the behavior in its natural context. However, people might change their behavior in unexpected ways if they know they are being observed. How do researchers obtain accurate information when people tend to hide their natural behavior? As an example, imagine that your professor asks everyone in your class to raise their hand if they always wash their hands after using the restroom. Chances are that almost everyone in the classroom will raise their hand, but do you think hand washing after every trip to the restroom is really that universal? This is very similar to the phenomenon mentioned earlier in this chapter: many individuals do not feel comfortable answering a question honestly. But if we are committed to finding out the facts about hand washing, we have other options available to us. Suppose we send a classmate into the restroom to actually watch whether everyone washes their hands after using the restroom. Will our observer blend into the restroom environment by wearing a white lab coat, sitting with a clipboard, and staring at the sinks? We want our researcher to be inconspicuous—perhaps standing at one of the sinks pretending to put in contact lenses while secretly recording the relevant information. This type of observational study is called naturalistic observation : observing behavior in its natural setting. To better understand peer exclusion, Suzanne Fanger collaborated with colleagues at the University of Texas to observe the behavior of preschool children on a playground. How did the observers remain inconspicuous over the duration of the study? They equipped a few of the children with wireless microphones (which the children quickly forgot about) and observed while taking notes from a distance. Also, the children in that particular preschool (a “laboratory preschool”) were accustomed to having observers on the playground (Fanger, Frankel, & Hazen, 2012). It is critical that the observer be as unobtrusive and as inconspicuous as possible: when people know they are being watched, they are less likely to behave naturally. If you have any doubt about this, ask yourself how your driving behavior might differ in two situations: In the first situation, you are driving down a deserted highway during the middle of the day; in the second situation, you are being followed by a police car down the same deserted highway ( Figure 2.7 ). It should be pointed out that naturalistic observation is not limited to research involving humans. Indeed, some of the best-known examples of naturalistic observation involve researchers going into the field to observe various kinds of animals in their own environments. As with human studies, the researchers maintain their distance and avoid interfering with the animal subjects so as not to influence their natural behaviors. Scientists have used this technique to study social hierarchies and interactions among animals ranging from ground squirrels to gorillas. The information provided by these studies is invaluable in understanding how those animals organize socially and communicate with one another. The anthropologist Jane Goodall , for example, spent nearly five decades observing the behavior of chimpanzees in Africa ( Figure 2.8 ). As an illustration of the types of concerns that a researcher might encounter in naturalistic observation, some scientists criticized Goodall for giving the chimps names instead of referring to them by numbers—using names was thought to undermine the emotional detachment required for the objectivity of the study (McKie, 2010). The greatest benefit of naturalistic observation is the validity , or accuracy, of information collected unobtrusively in a natural setting. Having individuals behave as they normally would in a given situation means that we have a higher degree of ecological validity, or realism, than we might achieve with other research approaches. Therefore, our ability to generalize the findings of the research to real-world situations is enhanced. If done correctly, we need not worry about people or animals modifying their behavior simply because they are being observed. Sometimes, people may assume that reality programs give us a glimpse into authentic human behavior. However, the principle of inconspicuous observation is violated as reality stars are followed by camera crews and are interviewed on camera for personal confessionals. Given that environment, we must doubt how natural and realistic their behaviors are. The major downside of naturalistic observation is that they are often difficult to set up and control. In our restroom study, what if you stood in the restroom all day prepared to record people’s hand washing behavior and no one came in? Or, what if you have been closely observing a troop of gorillas for weeks only to find that they migrated to a new place while you were sleeping in your tent? The benefit of realistic data comes at a cost. As a researcher you have no control of when (or if) you have behavior to observe. In addition, this type of observational research often requires significant investments of time, money, and a good dose of luck. Sometimes studies involve structured observation. In these cases, people are observed while engaging in set, specific tasks. An excellent example of structured observation comes from Strange Situation by Mary Ainsworth (you will read more about this in the chapter on lifespan development). The Strange Situation is a procedure used to evaluate attachment styles that exist between an infant and caregiver. In this scenario, caregivers bring their infants into a room filled with toys. The Strange Situation involves a number of phases, including a stranger coming into the room, the caregiver leaving the room, and the caregiver’s return to the room. The infant’s behavior is closely monitored at each phase, but it is the behavior of the infant upon being reunited with the caregiver that is most telling in terms of characterizing the infant’s attachment style with the caregiver. Another potential problem in observational research is observer bias . Generally, people who act as observers are closely involved in the research project and may unconsciously skew their observations to fit their research goals or expectations. To protect against this type of bias, researchers should have clear criteria established for the types of behaviors recorded and how those behaviors should be classified. In addition, researchers often compare observations of the same event by multiple observers, in order to test inter-rater reliability : a measure of reliability that assesses the consistency of observations by different observers. Surveys Often, psychologists develop surveys as a means of gathering data. Surveys are lists of questions to be answered by research participants, and can be delivered as paper-and-pencil questionnaires, administered electronically, or conducted verbally ( Figure 2.9 ). Generally, the survey itself can be completed in a short time, and the ease of administering a survey makes it easy to collect data from a large number of people. Surveys allow researchers to gather data from larger samples than may be afforded by other research methods . A sample is a subset of individuals selected from a population , which is the overall group of individuals that the researchers are interested in. Researchers study the sample and seek to generalize their findings to the population. There is both strength and weakness of the survey in comparison to case studies. By using surveys, we can collect information from a larger sample of people. A larger sample is better able to reflect the actual diversity of the population, thus allowing better generalizability. Therefore, if our sample is sufficiently large and diverse, we can assume that the data we collect from the survey can be generalized to the larger population with more certainty than the information collected through a case study. However, given the greater number of people involved, we are not able to collect the same depth of information on each person that would be collected in a case study. Another potential weakness of surveys is something we touched on earlier in this chapter: People don't always give accurate responses. They may lie, misremember, or answer questions in a way that they think makes them look good. For example, people may report drinking less alcohol than is actually the case. Any number of research questions can be answered through the use of surveys. One real-world example is the research conducted by Jenkins, Ruppel, Kizer, Yehl, and Griffin (2012) about the backlash against the US Arab-American community following the terrorist attacks of September 11, 2001. Jenkins and colleagues wanted to determine to what extent these negative attitudes toward Arab-Americans still existed nearly a decade after the attacks occurred. In one study, 140 research participants filled out a survey with 10 questions, including questions asking directly about the participant’s overt prejudicial attitudes toward people of various ethnicities. The survey also asked indirect questions about how likely the participant would be to interact with a person of a given ethnicity in a variety of settings (such as, “How likely do you think it is that you would introduce yourself to a person of Arab-American descent?”). The results of the research suggested that participants were unwilling to report prejudicial attitudes toward any ethnic group. However, there were significant differences between their pattern of responses to questions about social interaction with Arab-Americans compared to other ethnic groups: they indicated less willingness for social interaction with Arab-Americans compared to the other ethnic groups. This suggested that the participants harbored subtle forms of prejudice against Arab-Americans, despite their assertions that this was not the case (Jenkins et al., 2012). Archival Research Some researchers gain access to large amounts of data without interacting with a single research participant. Instead, they use existing records to answer various research questions. This type of research approach is known as archival research . Archival research relies on looking at past records or data sets to look for interesting patterns or relationships. For example, a researcher might access the academic records of all individuals who enrolled in college within the past ten years and calculate how long it took them to complete their degrees, as well as course loads, grades, and extracurricular involvement. Archival research could provide important information about who is most likely to complete their education, and it could help identify important risk factors for struggling students ( Figure 2.10 ). In comparing archival research to other research methods, there are several important distinctions. For one, the researcher employing archival research never directly interacts with research participants. Therefore, the investment of time and money to collect data is considerably less with archival research. Additionally, researchers have no control over what information was originally collected. Therefore, research questions have to be tailored so they can be answered within the structure of the existing data sets. There is also no guarantee of consistency between the records from one source to another, which might make comparing and contrasting different data sets problematic. Longitudinal and Cross-Sectional Research Sometimes we want to see how people change over time, as in studies of human development and lifespan. When we test the same group of individuals repeatedly over an extended period of time, we are conducting longitudinal research. Longitudinal research is a research design in which data-gathering is administered repeatedly over an extended period of time. For example, we may survey a group of individuals about their dietary habits at age 20, retest them a decade later at age 30, and then again at age 40. Another approach is cross-sectional research. In cross-sectional research , a researcher compares multiple segments of the population at the same time. Using the dietary habits example above, the researcher might directly compare different groups of people by age. Instead a group of people for 20 years to see how their dietary habits changed from decade to decade, the researcher would study a group of 20-year-old individuals and compare them to a group of 30-year-old individuals and a group of 40-year-old individuals. While cross-sectional research requires a shorter-term investment, it is also limited by differences that exist between the different generations (or cohorts) that have nothing to do with age per se, but rather reflect the social and cultural experiences of different generations of individuals make them different from one another. To illustrate this concept, consider the following survey findings. In recent years there has been significant growth in the popular support of same-sex marriage. Many studies on this topic break down survey participants into different age groups. In general, younger people are more supportive of same-sex marriage than are those who are older (Jones, 2013). Does this mean that as we age we become less open to the idea of same-sex marriage, or does this mean that older individuals have different perspectives because of the social climates in which they grew up? Longitudinal research is a powerful approach because the same individuals are involved in the research project over time, which means that the researchers need to be less concerned with differences among cohorts affecting the results of their study. Often longitudinal studies are employed when researching various diseases in an effort to understand particular risk factors. Such studies often involve tens of thousands of individuals who are followed for several decades. Given the enormous number of people involved in these studies, researchers can feel confident that their findings can be generalized to the larger population. The Cancer Prevention Study-3 (CPS-3) is one of a series of longitudinal studies sponsored by the American Cancer Society aimed at determining predictive risk factors associated with cancer. When participants enter the study, they complete a survey about their lives and family histories, providing information on factors that might cause or prevent the development of cancer. Then every few years the participants receive additional surveys to complete. In the end, hundreds of thousands of participants will be tracked over 20 years to determine which of them develop cancer and which do not. Clearly, this type of research is important and potentially very informative. For instance, earlier longitudinal studies sponsored by the American Cancer Society provided some of the first scientific demonstrations of the now well-established links between increased rates of cancer and smoking (American Cancer Society, n.d.) ( Figure 2.11 ). As with any research strategy, longitudinal research is not without limitations. For one, these studies require an incredible time investment by the researcher and research participants. Given that some longitudinal studies take years, if not decades, to complete, the results will not be known for a considerable period of time. In addition to the time demands, these studies also require a substantial financial investment. Many researchers are unable to commit the resources necessary to see a longitudinal project through to the end. Research participants must also be willing to continue their participation for an extended period of time, and this can be problematic. People move, get married and take new names, get ill, and eventually die. Even without significant life changes, some people may simply choose to discontinue their participation in the project. As a result, the attrition rates, or reduction in the number of research participants due to dropouts, in longitudinal studies are quite high and increases over the course of a project. For this reason, researchers using this approach typically recruit many participants fully expecting that a substantial number will drop out before the end. As the study progresses, they continually check whether the sample still represents the larger population, and make adjustments as necessary. 2.3 Analyzing Findings Learning Objectives By the end of this section, you will be able to: Explain what a correlation coefficient tells us about the relationship between variables Recognize that correlation does not indicate a cause-and-effect relationship between variables Discuss our tendency to look for relationships between variables that do not really exist Explain random sampling and assignment of participants into experimental and control groups Discuss how experimenter or participant bias could affect the results of an experiment Identify independent and dependent variables Did you know that as sales in ice cream increase, so does the overall rate of crime? Is it possible that indulging in your favorite flavor of ice cream could send you on a crime spree? Or, after committing crime do you think you might decide to treat yourself to a cone? There is no question that a relationship exists between ice cream and crime (e.g., Harper, 2013), but it would be pretty foolish to decide that one thing actually caused the other to occur. It is much more likely that both ice cream sales and crime rates are related to the temperature outside. When the temperature is warm, there are lots of people out of their houses, interacting with each other, getting annoyed with one another, and sometimes committing crimes. Also, when it is warm outside, we are more likely to seek a cool treat like ice cream. How do we determine if there is indeed a relationship between two things? And when there is a relationship, how can we discern whether it is attributable to coincidence or causation? Correlational Research Correlation means that there is a relationship between two or more variables (such as ice cream consumption and crime), but this relationship does not necessarily imply cause and effect. When two variables are correlated, it simply means that as one variable changes, so does the other. We can measure correlation by calculating a statistic known as a correlation coefficient. A correlation coefficient is a number from -1 to +1 that indicates the strength and direction of the relationship between variables. The correlation coefficient is usually represented by the letter r . The number portion of the correlation coefficient indicates the strength of the relationship. The closer the number is to 1 (be it negative or positive), the more strongly related the variables are, and the more predictable changes in one variable will be as the other variable changes. The closer the number is to zero, the weaker the relationship, and the less predictable the relationships between the variables becomes. For instance, a correlation coefficient of 0.9 indicates a far stronger relationship than a correlation coefficient of 0.3. If the variables are not related to one another at all, the correlation coefficient is 0. The example above about ice cream and crime is an example of two variables that we might expect to have no relationship to each other. The sign—positive or negative—of the correlation coefficient indicates the direction of the relationship ( Figure 2.12 ). A positive correlation means that the variables move in the same direction. Put another way, it means that as one variable increases so does the other, and conversely, when one variable decreases so does the other. A negative correlation means that the variables move in opposite directions. If two variables are negatively correlated, a decrease in one variable is associated with an increase in the other and vice versa. The example of ice cream and crime rates is a positive correlation because both variables increase when temperatures are warmer. Other examples of positive correlations are the relationship between an individual’s height and weight or the relationship between a person’s age and number of wrinkles. One might expect a negative correlation to exist between someone’s tiredness during the day and the number of hours they slept the previous night: the amount of sleep decreases as the feelings of tiredness increase. In a real-world example of negative correlation, student researchers at the University of Minnesota found a weak negative correlation ( r = -0.29) between the average number of days per week that students got fewer than 5 hours of sleep and their GPA (Lowry, Dean, & Manders, 2010). Keep in mind that a negative correlation is not the same as no correlation. For example, we would probably find no correlation between hours of sleep and shoe size. As mentioned earlier, correlations have predictive value. Imagine that you are on the admissions committee of a major university. You are faced with a huge number of applications, but you are able to accommodate only a small percentage of the applicant pool. How might you decide who should be admitted? You might try to correlate your current students’ college GPA with their scores on standardized tests like the SAT or ACT. By observing which correlations were strongest for your current students, you could use this information to predict relative success of those students who have applied for admission into the university. Link to Learning Manipulate this interactive scatterplot to practice your understanding of positive and negative correlation. Correlation Does Not Indicate Causation Correlational research is useful because it allows us to discover the strength and direction of relationships that exist between two variables. However, correlation is limited because establishing the existence of a relationship tells us little about cause and effect . While variables are sometimes correlated because one does cause the other, it could also be that some other factor, a confounding variable , is actually causing the systematic movement in our variables of interest. In the ice cream/crime rate example mentioned earlier, temperature is a confounding variable that could account for the relationship between the two variables. Even when we cannot point to clear confounding variables, we should not assume that a correlation between two variables implies that one variable causes changes in another. This can be frustrating when a cause-and-effect relationship seems clear and intuitive. Think back to our discussion of the research done by the American Cancer Society and how their research projects were some of the first demonstrations of the link between smoking and cancer. It seems reasonable to assume that smoking causes cancer, but if we were limited to correlational research , we would be overstepping our bounds by making this assumption. Unfortunately, people mistakenly make claims of causation as a function of correlations all the time. Such claims are especially common in advertisements and news stories. For example, recent research found that people who eat cereal on a regular basis achieve healthier weights than those who rarely eat cereal (Frantzen, Treviño, Echon, Garcia-Dominic, & DiMarco, 2013; Barton et al., 2005). Guess how the cereal companies report this finding. Does eating cereal really cause an individual to maintain a healthy weight, or are there other possible explanations, such as, someone at a healthy weight is more likely to regularly eat a healthy breakfast than someone who is obese or someone who avoids meals in an attempt to diet ( Figure 2.13 )? While correlational research is invaluable in identifying relationships among variables, a major limitation is the inability to establish causality. Psychologists want to make statements about cause and effect, but the only way to do that is to conduct an experiment to answer a research question. The next section describes how scientific experiments incorporate methods that eliminate, or control for, alternative explanations, which allow researchers to explore how changes in one variable cause changes in another variable. Illusory Correlations The temptation to make erroneous cause-and-effect statements based on correlational research is not the only way we tend to misinterpret data. We also tend to make the mistake of illusory correlations, especially with unsystematic observations. Illusory correlations , or false correlations, occur when people believe that relationships exist between two things when no such relationship exists. One well-known illusory correlation is the supposed effect that the moon’s phases have on human behavior. Many people passionately assert that human behavior is affected by the phase of the moon, and specifically, that people act strangely when the moon is full ( Figure 2.14 ). There is no denying that the moon exerts a powerful influence on our planet. The ebb and flow of the ocean’s tides are tightly tied to the gravitational forces of the moon. Many people believe, therefore, that it is logical that we are affected by the moon as well. After all, our bodies are largely made up of water. A meta-analysis of nearly 40 studies consistently demonstrated, however, that the relationship between the moon and our behavior does not exist (Rotton & Kelly, 1985). While we may pay more attention to odd behavior during the full phase of the moon, the rates of odd behavior remain constant throughout the lunar cycle. Why are we so apt to believe in illusory correlations like this? Often we read or hear about them and simply accept the information as valid. Or, we have a hunch about how something works and then look for evidence to support that hunch, ignoring evidence that would tell us our hunch is false; this is known as confirmation bias . Other times, we find illusory correlations based on the information that comes most easily to mind, even if that information is severely limited. And while we may feel confident that we can use these relationships to better understand and predict the world around us, illusory correlations can have significant drawbacks. For example, research suggests that illusory correlations—in which certain behaviors are inaccurately attributed to certain groups—are involved in the formation of prejudicial attitudes that can ultimately lead to discriminatory behavior (Fiedler, 2004). Causality: Conducting Experiments and Using the Data As you’ve learned, the only way to establish that there is a cause-and-effect relationship between two variables is to conduct a scientific experiment . Experiment has a different meaning in the scientific context than in everyday life. In everyday conversation, we often use it to describe trying something for the first time, such as experimenting with a new hair style or a new food. However, in the scientific context, an experiment has precise requirements for design and implementation. The Experimental Hypothesis In order to conduct an experiment, a researcher must have a specific hypothesis to be tested. As you’ve learned, hypotheses can be formulated either through direct observation of the real world or after careful review of previous research. For example, if you think that children should not be allowed to watch violent programming on television because doing so would cause them to behave more violently, then you have basically formulated a hypothesis—namely, that watching violent television programs causes children to behave more violently. How might you have arrived at this particular hypothesis? You may have younger relatives who watch cartoons featuring characters using martial arts to save the world from evildoers, with an impressive array of punching, kicking, and defensive postures. You notice that after watching these programs for a while, your young relatives mimic the fighting behavior of the characters portrayed in the cartoon ( Figure 2.15 ). These sorts of personal observations are what often lead us to formulate a specific hypothesis, but we cannot use limited personal observations and anecdotal evidence to rigorously test our hypothesis. Instead, to find out if real-world data supports our hypothesis, we have to conduct an experiment. Designing an Experiment The most basic experimental design involves two groups: the experimental group and the control group. The two groups are designed to be the same except for one difference— experimental manipulation. The experimental group gets the experimental manipulation—that is, the treatment or variable being tested (in this case, violent TV images)—and the control group does not. Since experimental manipulation is the only difference between the experimental and control groups, we can be sure that any differences between the two are due to experimental manipulation rather than chance. In our example of how violent television programming might affect violent behavior in children, we have the experimental group view violent television programming for a specified time and then measure their violent behavior. We measure the violent behavior in our control group after they watch nonviolent television programming for the same amount of time. It is important for the control group to be treated similarly to the experimental group, with the exception that the control group does not receive the experimental manipulation. Therefore, we have the control group watch non-violent television programming for the same amount of time as the experimental group. We also need to precisely define, or operationalize, what is considered violent and nonviolent. An operational definition is a description of how we will measure our variables, and it is important in allowing others understand exactly how and what a researcher measures in a particular experiment. In operationalizing violent behavior, we might choose to count only physical acts like kicking or punching as instances of this behavior, or we also may choose to include angry verbal exchanges. Whatever we determine, it is important that we operationalize violent behavior in such a way that anyone who hears about our study for the first time knows exactly what we mean by violence. This aids peoples’ ability to interpret our data as well as their capacity to repeat our experiment should they choose to do so. Once we have operationalized what is considered violent television programming and what is considered violent behavior from our experiment participants, we need to establish how we will run our experiment. In this case, we might have participants watch a 30-minute television program (either violent or nonviolent, depending on their group membership) before sending them out to a playground for an hour where their behavior is observed and the number and type of violent acts is recorded. Ideally, the people who observe and record the children’s behavior are unaware of who was assigned to the experimental or control group, in order to control for experimenter bias. Experimenter bias refers to the possibility that a researcher’s expectations might skew the results of the study. Remember, conducting an experiment requires a lot of planning, and the people involved in the research project have a vested interest in supporting their hypotheses. If the observers knew which child was in which group, it might influence how much attention they paid to each child’s behavior as well as how they interpreted that behavior. By being blind to which child is in which group, we protect against those biases. This situation is a single-blind study , meaning that one of the groups (participants) are unaware as to which group they are in (experiment or control group) while the researcher who developed the experiment knows which participants are in each group. In a double-blind study , both the researchers and the participants are blind to group assignments. Why would a researcher want to run a study where no one knows who is in which group? Because by doing so, we can control for both experimenter and participant expectations. If you are familiar with the phrase placebo effect , you already have some idea as to why this is an important consideration. The placebo effect occurs when people's expectations or beliefs influence or determine their experience in a given situation. In other words, simply expecting something to happen can actually make it happen. The placebo effect is commonly described in terms of testing the effectiveness of a new medication. Imagine that you work in a pharmaceutical company, and you think you have a new drug that is effective in treating depression. To demonstrate that your medication is effective, you run an experiment with two groups: The experimental group receives the medication, and the control group does not. But you don’t want participants to know whether they received the drug or not. Why is that? Imagine that you are a participant in this study, and you have just taken a pill that you think will improve your mood. Because you expect the pill to have an effect, you might feel better simply because you took the pill and not because of any drug actually contained in the pill—this is the placebo effect. To make sure that any effects on mood are due to the drug and not due to expectations, the control group receives a placebo (in this case a sugar pill). Now everyone gets a pill, and once again neither the researcher nor the experimental participants know who got the drug and who got the sugar pill. Any differences in mood between the experimental and control groups can now be attributed to the drug itself rather than to experimenter bias or participant expectations ( Figure 2.16 ). Independent and Dependent Variables In a research experiment, we strive to study whether changes in one thing cause changes in another. To achieve this, we must pay attention to two important variables, or things that can be changed, in any experimental study: the independent variable and the dependent variable. An independent variable is manipulated or controlled by the experimenter. In a well-designed experimental study, the independent variable is the only important difference between the experimental and control groups. In our example of how violent television programs affect children’s display of violent behavior, the independent variable is the type of program—violent or nonviolent—viewed by participants in the study ( Figure 2.17 ). A dependent variable is what the researcher measures to see how much effect the independent variable had. In our example, the dependent variable is the number of violent acts displayed by the experimental participants. We expect that the dependent variable will change as a function of the independent variable. In other words, the dependent variable depends on the independent variable. A good way to think about the relationship between the independent and dependent variables is with this question: What effect does the independent variable have on the dependent variable? Returning to our example, what effect does watching a half hour of violent television programming or nonviolent television programming have on the number of incidents of physical aggression displayed on the playground? Selecting and Assigning Experimental Participants Now that our study is designed, we need to obtain a sample of individuals to include in our experiment. Our study involves human participants so we need to determine who to include. Participants are the subjects of psychological research, and as the name implies, individuals who are involved in psychological research actively participate in the process. Often, psychological research projects rely on college students to serve as participants. In fact, the vast majority of research in psychology subfields has historically involved students as research participants (Sears, 1986; Arnett, 2008). But are college students truly representative of the general population? College students tend to be younger, more educated, more liberal, and less diverse than the general population. Although using students as test subjects is an accepted practice, relying on such a limited pool of research participants can be problematic because it is difficult to generalize findings to the larger population. Our hypothetical experiment involves children, and we must first generate a sample of child participants. Samples are used because populations are usually too large to reasonably involve every member in our particular experiment ( Figure 2.18 ). If possible, we should use a random sample (there are other types of samples, but for the purposes of this chapter, we will focus on random samples). A random sample is a subset of a larger population in which every member of the population has an equal chance of being selected. Random samples are preferred because if the sample is large enough we can be reasonably sure that the participating individuals are representative of the larger population. This means that the percentages of characteristics in the sample—sex, ethnicity, socioeconomic level, and any other characteristics that might affect the results—are close to those percentages in the larger population. In our example, let’s say we decide our population of interest is fourth graders. But all fourth graders is a very large population, so we need to be more specific; instead we might say our population of interest is all fourth graders in a particular city. We should include students from various income brackets, family situations, races, ethnicities, religions, and geographic areas of town. With this more manageable population, we can work with the local schools in selecting a random sample of around 200 fourth graders who we want to participate in our experiment. In summary, because we cannot test all of the fourth graders in a city, we want to find a group of about 200 that reflects the composition of that city. With a representative group, we can generalize our findings to the larger population without fear of our sample being biased in some way. Now that we have a sample, the next step of the experimental process is to split the participants into experimental and control groups through random assignment. With random assignment , all participants have an equal chance of being assigned to either group. There is statistical software that will randomly assign each of the fourth graders in the sample to either the experimental or the control group. Random assignment is critical for sound experimental design . With sufficiently large samples, random assignment makes it unlikely that there are systematic differences between the groups. So, for instance, it would be very unlikely that we would get one group composed entirely of males, a given ethnic identity, or a given religious ideology. This is important because if the groups were systematically different before the experiment began, we would not know the origin of any differences we find between the groups: Were the differences preexisting, or were they caused by manipulation of the independent variable? Random assignment allows us to assume that any differences observed between experimental and control groups result from the manipulation of the independent variable. Link to Learning Use this online tool to instantly generate randomized numbers and to learn more about random sampling and assignments. Issues to Consider While experiments allow scientists to make cause-and-effect claims, they are not without problems. True experiments require the experimenter to manipulate an independent variable, and that can complicate many questions that psychologists might want to address. For instance, imagine that you want to know what effect sex (the independent variable) has on spatial memory (the dependent variable). Although you can certainly look for differences between males and females on a task that taps into spatial memory, you cannot directly control a person’s sex. We categorize this type of research approach as quasi-experimental and recognize that we cannot make cause-and-effect claims in these circumstances. Experimenters are also limited by ethical constraints. For instance, you would not be able to conduct an experiment designed to determine if experiencing abuse as a child leads to lower levels of self-esteem among adults. To conduct such an experiment, you would need to randomly assign some experimental participants to a group that receives abuse, and that experiment would be unethical. Interpreting Experimental Findings Once data is collected from both the experimental and the control groups, a statistical analysis is conducted to find out if there are meaningful differences between the two groups. A statistical analysis determines how likely any difference found is due to chance (and thus not meaningful). In psychology, group differences are considered meaningful, or significant, if the odds that these differences occurred by chance alone are 5 percent or less. Stated another way, if we repeated this experiment 100 times, we would expect to find the same results at least 95 times out of 100. The greatest strength of experiments is the ability to assert that any significant differences in the findings are caused by the independent variable. This occurs because random selection, random assignment, and a design that limits the effects of both experimenter bias and participant expectancy should create groups that are similar in composition and treatment. Therefore, any difference between the groups is attributable to the independent variable, and now we can finally make a causal statement. If we find that watching a violent television program results in more violent behavior than watching a nonviolent program, we can safely say that watching violent television programs causes an increase in the display of violent behavior. Reporting Research When psychologists complete a research project, they generally want to share their findings with other scientists. The American Psychological Association (APA) publishes a manual detailing how to write a paper for submission to scientific journals. Unlike an article that might be published in a magazine like Psychology Today, which targets a general audience with an interest in psychology, scientific journals generally publish peer-reviewed journal articles aimed at an audience of professionals and scholars who are actively involved in research themselves. Link to Learning The Online Writing Lab (OWL) at Purdue University can walk you through the APA writing guidelines. A peer-reviewed journal article is read by several other scientists (generally anonymously) with expertise in the subject matter. These peer reviewers provide feedback—to both the author and the journal editor—regarding the quality of the draft. Peer reviewers look for a strong rationale for the research being described, a clear description of how the research was conducted, and evidence that the research was conducted in an ethical manner. They also look for flaws in the study's design, methods, and statistical analyses. They check that the conclusions drawn by the authors seem reasonable given the observations made during the research. Peer reviewers also comment on how valuable the research is in advancing the discipline’s knowledge. This helps prevent unnecessary duplication of research findings in the scientific literature and, to some extent, ensures that each research article provides new information. Ultimately, the journal editor will compile all of the peer reviewer feedback and determine whether the article will be published in its current state (a rare occurrence), published with revisions, or not accepted for publication. Peer review provides some degree of quality control for psychological research. Poorly conceived or executed studies can be weeded out, and even well-designed research can be improved by the revisions suggested. Peer review also ensures that the research is described clearly enough to allow other scientists to replicate it, meaning they can repeat the experiment using different samples to determine reliability. Sometimes replications involve additional measures that expand on the original finding. In any case, each replication serves to provide more evidence to support the original research findings. Successful replications of published research make scientists more apt to adopt those findings, while repeated failures tend to cast doubt on the legitimacy of the original article and lead scientists to look elsewhere. For example, it would be a major advancement in the medical field if a published study indicated that taking a new drug helped individuals achieve a healthy weight without changing their diet. But if other scientists could not replicate the results, the original study’s claims would be questioned. Dig Deeper The Vaccine-Autism Myth and Retraction of Published Studies Some scientists have claimed that routine childhood vaccines cause some children to develop autism, and, in fact, several peer-reviewed publications published research making these claims. Since the initial reports, large-scale epidemiological research has suggested that vaccinations are not responsible for causing autism and that it is much safer to have your child vaccinated than not. Furthermore, several of the original studies making this claim have since been retracted. A published piece of work can be rescinded when data is called into question because of falsification, fabrication, or serious research design problems. Once rescinded, the scientific community is informed that there are serious problems with the original publication. Retractions can be initiated by the researcher who led the study, by research collaborators, by the institution that employed the researcher, or by the editorial board of the journal in which the article was originally published. In the vaccine-autism case, the retraction was made because of a significant conflict of interest in which the leading researcher had a financial interest in establishing a link between childhood vaccines and autism (Offit, 2008). Unfortunately, the initial studies received so much media attention that many parents around the world became hesitant to have their children vaccinated ( Figure 2.19 ). For more information about how the vaccine/autism story unfolded, as well as the repercussions of this story, take a look at Paul Offit’s book, Autism’s False Prophets: Bad Science, Risky Medicine, and the Search for a Cure. Reliability and Validity Reliability and validity are two important considerations that must be made with any type of data collection. Reliability refers to the ability to consistently produce a given result. In the context of psychological research, this would mean that any instruments or tools used to collect data do so in consistent, reproducible ways. Unfortunately, being consistent in measurement does not necessarily mean that you have measured something correctly. To illustrate this concept, consider a kitchen scale that would be used to measure the weight of cereal that you eat in the morning. If the scale is not properly calibrated, it may consistently under- or overestimate the amount of cereal that’s being measured. While the scale is highly reliable in producing consistent results (e.g., the same amount of cereal poured onto the scale produces the same reading each time), those results are incorrect. This is where validity comes into play. Validity refers to the extent to which a given instrument or tool accurately measures what it’s supposed to measure. While any valid measure is by necessity reliable, the reverse is not necessarily true. Researchers strive to use instruments that are both highly reliable and valid. Everyday Connection How Valid Is the SAT? Standardized tests like the SAT are supposed to measure an individual’s aptitude for a college education, but how reliable and valid are such tests? Research conducted by the College Board suggests that scores on the SAT have high predictive validity for first-year college students’ GPA (Kobrin, Patterson, Shaw, Mattern, & Barbuti, 2008). In this context, predictive validity refers to the test’s ability to effectively predict the GPA of college freshmen. Given that many institutions of higher education require the SAT for admission, this high degree of predictive validity might be comforting. However, the emphasis placed on SAT scores in college admissions has generated some controversy on a number of fronts. For one, some researchers assert that the SAT is a biased test that places minority students at a disadvantage and unfairly reduces the likelihood of being admitted into a college (Santelices & Wilson, 2010). Additionally, some research has suggested that the predictive validity of the SAT is grossly exaggerated in how well it is able to predict the GPA of first-year college students. In fact, it has been suggested that the SAT’s predictive validity may be overestimated by as much as 150% (Rothstein, 2004). Many institutions of higher education are beginning to consider de-emphasizing the significance of SAT scores in making admission decisions (Rimer, 2008). In 2014, College Board president David Coleman expressed his awareness of these problems, recognizing that college success is more accurately predicted by high school grades than by SAT scores. To address these concerns, he has called for significant changes to the SAT exam (Lewin, 2014). 2.4 Ethics Learning Objectives By the end of this section, you will be able to: Discuss how research involving human subjects is regulated Summarize the processes of informed consent and debriefing Explain how research involving animal subjects is regulated Today, scientists agree that good research is ethical in nature and is guided by a basic respect for human dignity and safety. However, as you will read in the feature box, this has not always been the case. Modern researchers must demonstrate that the research they perform is ethically sound. This section presents how ethical considerations affect the design and implementation of research conducted today. Research Involving Human Participants Any experiment involving the participation of human subjects is governed by extensive, strict guidelines designed to ensure that the experiment does not result in harm. Any research institution that receives federal support for research involving human participants must have access to an institutional review board (IRB) . The IRB is a committee of individuals often made up of members of the institution’s administration, scientists, and community members ( Figure 2.20 ). The purpose of the IRB is to review proposals for research that involves human participants. The IRB reviews these proposals with the principles mentioned above in mind, and generally, approval from the IRB is required in order for the experiment to proceed. An institution’s IRB requires several components in any experiment it approves. For one, each participant must sign an informed consent form before they can participate in the experiment. An informed consent form provides a written description of what participants can expect during the experiment, including potential risks and implications of the research. It also lets participants know that their involvement is completely voluntary and can be discontinued without penalty at any time. Furthermore, the informed consent guarantees that any data collected in the experiment will remain completely confidential. In cases where research participants are under the age of 18, the parents or legal guardians are required to sign the informed consent form. Link to Learning Visit this website to see an example of a consent form. While the informed consent form should be as honest as possible in describing exactly what participants will be doing, sometimes deception is necessary to prevent participants’ knowledge of the exact research question from affecting the results of the study. Deception involves purposely misleading experiment participants in order to maintain the integrity of the experiment, but not to the point where the deception could be considered harmful. For example, if we are interested in how our opinion of someone is affected by their attire, we might use deception in describing the experiment to prevent that knowledge from affecting participants’ responses. In cases where deception is involved, participants must receive a full debriefing upon conclusion of the study—complete, honest information about the purpose of the experiment, how the data collected will be used, the reasons why deception was necessary, and information about how to obtain additional information about the study. Dig Deeper Ethics and the Tuskegee Syphilis Study Unfortunately, the ethical guidelines that exist for research today were not always applied in the past. In 1932, poor, rural, black, male sharecroppers from Tuskegee, Alabama, were recruited to participate in an experiment conducted by the U.S. Public Health Service, with the aim of studying syphilis in black men ( Figure 2.21 ). In exchange for free medical care, meals, and burial insurance, 600 men agreed to participate in the study. A little more than half of the men tested positive for syphilis, and they served as the experimental group (given that the researchers could not randomly assign participants to groups, this represents a quasi-experiment). The remaining syphilis-free individuals served as the control group. However, those individuals that tested positive for syphilis were never informed that they had the disease. While there was no treatment for syphilis when the study began, by 1947 penicillin was recognized as an effective treatment for the disease. Despite this, no penicillin was administered to the participants in this study, and the participants were not allowed to seek treatment at any other facilities if they continued in the study. Over the course of 40 years, many of the participants unknowingly spread syphilis to their wives (and subsequently their children born from their wives) and eventually died because they never received treatment for the disease. This study was discontinued in 1972 when the experiment was discovered by the national press (Tuskegee University, n.d.). The resulting outrage over the experiment led directly to the National Research Act of 1974 and the strict ethical guidelines for research on humans described in this chapter. Why is this study unethical? How were the men who participated and their families harmed as a function of this research? Link to Learning Visit this website to learn more about the Tuskegee Syphilis Study. Research Involving Animal Subjects Many psychologists conduct research involving animal subjects. Often, these researchers use rodents ( Figure 2.22 ) or birds as the subjects of their experiments—the APA estimates that 90% of all animal research in psychology uses these species (American Psychological Association, n.d.). Because many basic processes in animals are sufficiently similar to those in humans, these animals are acceptable substitutes for research that would be considered unethical in human participants. This does not mean that animal researchers are immune to ethical concerns. Indeed, the humane and ethical treatment of animal research subjects is a critical aspect of this type of research. Researchers must design their experiments to minimize any pain or distress experienced by animals serving as research subjects. Whereas IRBs review research proposals that involve human participants, animal experimental proposals are reviewed by an Institutional Animal Care and Use Committee (IACUC) . An IACUC consists of institutional administrators, scientists, veterinarians, and community members. This committee is charged with ensuring that all experimental proposals require the humane treatment of animal research subjects. It also conducts semi-annual inspections of all animal facilities to ensure that the research protocols are being followed. No animal research project can proceed without the committee’s approval.
u.s._history
Summary 2.1 Portuguese Exploration and Spanish Conquest Although Portugal opened the door to exploration of the Atlantic World, Spanish explorers quickly made inroads into the Americas. Spurred by Christopher Columbus’s glowing reports of the riches to be found in the New World, throngs of Spanish conquistadors set off to find and conquer new lands. They accomplished this through a combination of military strength and strategic alliances with native peoples. Spanish rulers Ferdinand and Isabella promoted the acquisition of these new lands in order to strengthen and glorify their own empire. As Spain’s empire expanded and riches flowed in from the Americas, the Spanish experienced a golden age of art and literature. 2.2 Religious Upheavals in the Developing Atlantic World The sixteenth century witnessed a new challenge to the powerful Catholic Church. The reformist doctrines of Martin Luther and John Calvin attracted many people dissatisfied with Catholicism, and Protestantism spread across northern Europe, spawning many subgroups with conflicting beliefs. Spain led the charge against Protestantism, leading to decades of undeclared religious wars between Spain and England, and religious intolerance and violence characterized much of the sixteenth and seventeenth centuries. Despite the efforts of the Catholic Church and Catholic nations, however, Protestantism had taken hold by 1600. 2.3 Challenges to Spain’s Supremacy By the beginning of the seventeenth century, Spain’s rivals—England, France, and the Dutch Republic—had each established an Atlantic presence, with greater or lesser success, in the race for imperial power. None of the new colonies, all in the eastern part of North America, could match the Spanish possessions for gold and silver resources. Nonetheless, their presence in the New World helped these nations establish claims that they hoped could halt the runaway growth of Spain’s Catholic empire. English colonists in Virginia suffered greatly, expecting riches to fall into their hands and finding reality a harsh blow. However, the colony at Jamestown survived, and the output of England’s islands in the West Indies soon grew to be an important source of income for the country. New France and New Netherlands were modest colonial holdings in the northeast of the continent, but these colonies’ thriving fur trade with native peoples, and their alliances with those peoples, helped to create the foundation for later shifts in the global balance of power. 2.4 New Worlds in the Americas: Labor, Commerce, and the Columbian Exchange In the minds of European rulers, colonies existed to create wealth for imperial powers. Guided by mercantilist ideas, European rulers and investors hoped to enrich their own nations and themselves, in order to gain the greatest share of what was believed to be a limited amount of wealth. In their own individual quest for riches and preeminence, European colonizers who traveled to the Americas blazed new and disturbing paths, such as the encomienda system of forced labor and the enslavement of tens of thousands of Africans. All Native inhabitants of the Americas who came into contact with Europeans found their worlds turned upside down as the new arrivals introduced their religions and ideas about property and goods. Europeans gained new foods, plants, and animals in the Columbian Exchange, turning whatever they could into a commodity to be bought and sold, and Native peoples were introduced to diseases that nearly destroyed them. At every turn, however, Native Americans placed limits on European colonization and resisted the newcomers’ ways.
Chapter Outline 2.1 Portuguese Exploration and Spanish Conquest 2.2 Religious Upheavals in the Developing Atlantic World 2.3 Challenges to Spain’s Supremacy 2.4 New Worlds in the Americas: Labor, Commerce, and the Columbian Exchange Introduction The story of the Atlantic World is the story of global migration, a migration driven in large part by the actions and aspirations of the ruling heads of Europe. Columbus is hardly visible in this illustration of his ships making landfall on the Caribbean island of Hispaniola ( Figure 2.1 ). Instead, Ferdinand II of Spain (in the foreground) sits on his throne and points toward Columbus’s landing. As the ships arrive, the Arawak people tower over the Spanish, suggesting the native population density of the islands. This historic moment in 1492 sparked new rivalries among European powers as they scrambled to create New World colonies, fueled by the quest for wealth and power as well as by religious passions. Almost continuous war resulted. Spain achieved early preeminence, creating a far-flung empire and growing rich with treasures from the Americas. Native Americans who confronted the newcomers from Europe suffered unprecedented losses of life, however, as previously unknown diseases sliced through their populations. They also were victims of the arrogance of the Europeans, who viewed themselves as uncontested masters of the New World, sent by God to bring Christianity to the “Indians.”
[ { "answer": { "ans_choice": 3, "ans_text": "D" }, "bloom": null, "hl_context": "<hl> Portuguese colonization of Atlantic islands in the 1400s inaugurated an era of aggressive European expansion across the Atlantic . <hl> In the 1500s , Spain surpassed Portugal as the dominant European power . This age of exploration and the subsequent creation of an Atlantic World marked the earliest phase of globalization , in which previously isolated groups — Africans , Native Americans , and Europeans — first came into contact with each other , sometimes with disastrous results .", "hl_sentences": "Portuguese colonization of Atlantic islands in the 1400s inaugurated an era of aggressive European expansion across the Atlantic .", "question": { "cloze_format": "The country of ___ initiated the era of Atlantic exploration.", "normal_format": "Which country initiated the era of Atlantic exploration?", "question_choices": [ "France", "Spain", "England", "Portugal" ], "question_id": "fs-idp11204496", "question_text": "Which country initiated the era of Atlantic exploration?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 2, "ans_text": "Spain" }, "bloom": null, "hl_context": "<hl> The Spanish established the first European settlements in the Americas , beginning in the Caribbean and , by 1600 , extending throughout Central and South America . <hl> Thousands of Spaniards flocked to the Americas seeking wealth and status . The most famous of these Spanish adventurers are Christopher Columbus ( who , though Italian himself , explored on behalf of the Spanish monarchs ) , Hernán Cortés , and Francisco Pizarro .", "hl_sentences": "The Spanish established the first European settlements in the Americas , beginning in the Caribbean and , by 1600 , extending throughout Central and South America .", "question": { "cloze_format": "___ is the country that established the first colonies in the Americas.", "normal_format": "Which country established the first colonies in the Americas?", "question_choices": [ "England", "Portugal", "Spain", "the Netherlands" ], "question_id": "fs-idm39224816", "question_text": "Which country established the first colonies in the Americas?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 1, "ans_text": "B" }, "bloom": null, "hl_context": "Columbus held erroneous views that shaped his thinking about what he would encounter as he sailed west . He believed the earth to be much smaller than its actual size and , since he did not know of the existence of the Americas , he fully expected to land in Asia . <hl> On October 12 , 1492 , however , he made landfall on an island in the Bahamas . <hl> He then sailed to an island he named Hispaniola ( present-day Dominican Republic and Haiti ) ( Figure 2.4 ) . Believing he had landed in the East Indies , Columbus called the native Taínos he found there “ Indios , ” giving rise to the term “ Indian ” for any native people of the New World . Upon Columbus ’ s return to Spain , the Spanish crown bestowed on him the title of Admiral of the Ocean Sea and named him governor and viceroy of the lands he had discovered . As a devoted Catholic , Columbus had agreed with Ferdinand and Isabella prior to sailing west that part of the expected wealth from his voyage would be used to continue the fight against Islam .", "hl_sentences": "On October 12 , 1492 , however , he made landfall on an island in the Bahamas .", "question": { "cloze_format": "Christopher Columbus first landed in ___", "normal_format": "Where did Christopher Columbus first land?", "question_choices": [ "Hispaniola", "the Bahamas", "Jamestown", "Mexico" ], "question_id": "fs-idm2880304", "question_text": "Where did Christopher Columbus first land?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 0, "ans_text": "A" }, "bloom": null, "hl_context": "<hl> During the sixteenth century , Protestantism spread through northern Europe , and Catholic countries responded by attempting to extinguish what was seen as the Protestant menace . <hl> Religious turmoil between Catholics and Protestants influenced the history of the Atlantic World as well , since different nation-states competed not only for control of new territories but also for the preeminence of their religious beliefs there . Just as the history of Spain ’ s rise to power is linked to the Reconquista , so too is the history of early globalization connected to the history of competing Christian groups in the Atlantic World .", "hl_sentences": "During the sixteenth century , Protestantism spread through northern Europe , and Catholic countries responded by attempting to extinguish what was seen as the Protestant menace .", "question": { "cloze_format": "The Protestant Reformation began in ___", "normal_format": "Where did the Protestant Reformation begin?", "question_choices": [ "Northern Europe", "Spain", "England", "the American colonies" ], "question_id": "fs-idm51792", "question_text": "Where did the Protestant Reformation begin?" }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 1, "ans_text": "to eliminate any traces of Catholicism from the Church of England" }, "bloom": null, "hl_context": "Religious turbulence in England was finally quieted when Elizabeth , the Protestant daughter of Henry VIII and Anne Boleyn , ascended the throne in 1558 . Under Elizabeth , the Church of England again became the state church , retaining the hierarchical structure and many of the rituals of the Catholic Church . However , by the late 1500s , some English members of the Church began to agitate for more reform . <hl> Known as Puritans , they worked to erase all vestiges of Catholicism from the Church of England . <hl> At the time , the term “ puritan ” was a pejorative one ; many people saw Puritans as holier-than-thou frauds who used religion to swindle their neighbors . Worse still , many in power saw Puritans as a security threat because of their opposition to the national church .", "hl_sentences": "Known as Puritans , they worked to erase all vestiges of Catholicism from the Church of England .", "question": { "cloze_format": "The chief goal of the Puritans was ___", "normal_format": "What was the chief goal of the Puritans?", "question_choices": [ "to achieve a lasting peace with the Catholic nations of Spain and France", "to eliminate any traces of Catholicism from the Church of England", "to assist Henry VIII in his quest for an annulment to his marriage", "to create a hierarchy within the Church of England modeled on that of the Catholic Church" ], "question_id": "fs-idp1567984", "question_text": "What was the chief goal of the Puritans?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 0, "ans_text": "English attention was turned to internal struggles and the encroaching Catholic menace to Scotland and Ireland." }, "bloom": null, "hl_context": "Queen Elizabeth favored England ’ s advance into the Atlantic World , though her main concern was blocking Spain ’ s effort to eliminate Protestantism . <hl> Indeed , England could not commit to large-scale colonization in the Americas as long as Spain appeared ready to invade Ireland or Scotland . <hl> Nonetheless , Elizabeth approved of English privateers , sea captains to whom the home government had given permission to raid the enemy at will . These skilled mariners cruised the Caribbean , plundering Spanish ships whenever they could . Each year the English took more than £ 100,000 from Spain in this way ; English privateer Francis Drake first made a name for himself when , in 1573 , he looted silver , gold , and pearls worth £ 40,000 . <hl> Disruptions during the Tudor monarchy — especially the creation of the Protestant Church of England by Henry VIII in the 1530s , the return of the nation to Catholicism under Queen Mary in the 1550s , and the restoration of Protestantism under Queen Elizabeth — left England with little energy for overseas projects . <hl> <hl> More important , England lacked the financial resources for such endeavors . <hl> Nonetheless , English monarchs carefully monitored developments in the new Atlantic World and took steps to assert England ’ s claim to the Americas . As early as 1497 , Henry VII of England had commissioned John Cabot , an Italian mariner , to explore new lands . Cabot sailed from England that year and made landfall somewhere along the North American coastline . For the next century , English fishermen routinely crossed the Atlantic to fish the rich waters off the North American coast . However , English colonization efforts in the 1500s were closer to home , as England devoted its energy to the colonization of Ireland .", "hl_sentences": "Indeed , England could not commit to large-scale colonization in the Americas as long as Spain appeared ready to invade Ireland or Scotland . Disruptions during the Tudor monarchy — especially the creation of the Protestant Church of England by Henry VIII in the 1530s , the return of the nation to Catholicism under Queen Mary in the 1550s , and the restoration of Protestantism under Queen Elizabeth — left England with little energy for overseas projects . More important , England lacked the financial resources for such endeavors .", "question": { "cloze_format": "England didn't make stronger attempts to colonize the New World before the late sixteenth to early seventeenth century because ___", "normal_format": "Why didn’t England make stronger attempts to colonize the New World before the late sixteenth to early seventeenth century?", "question_choices": [ "English attention was turned to internal struggles and the encroaching Catholic menace to Scotland and Ireland.", "The English monarchy did not want to declare direct war on Spain by attempting to colonize the Americas.", "The English military was occupied in battling for control of New Netherlands.", "The English crown refused to fund colonial expeditions." ], "question_id": "fs-idm83724880", "question_text": "Why didn’t England make stronger attempts to colonize the New World before the late sixteenth to early seventeenth century?" }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 1, "ans_text": "B" }, "bloom": null, "hl_context": "<hl> The French were primarily interested in establishing commercially viable colonial outposts , and to that end , they created extensive trading networks in New France . <hl> <hl> These networks relied on native hunters to harvest furs , especially beaver pelts , and to exchange these items for French glass beads and other trade goods . <hl> ( French fashion at the time favored broad-brimmed hats trimmed in beaver fur , so French traders had a ready market for their North American goods . ) The French also dreamed of replicating the wealth of Spain by colonizing the tropical zones . After Spanish control of the Caribbean began to weaken , the French turned their attention to small islands in the West Indies , and by 1635 they had colonized two , Guadeloupe and Martinique . Though it lagged far behind Spain , France now boasted its own West Indian colonies . Both islands became lucrative sugar plantation sites that turned a profit for French planters by relying on African slave labor .", "hl_sentences": "The French were primarily interested in establishing commercially viable colonial outposts , and to that end , they created extensive trading networks in New France . These networks relied on native hunters to harvest furs , especially beaver pelts , and to exchange these items for French glass beads and other trade goods .", "question": { "cloze_format": "The main goal of the French in colonizing the Americas was ___", "normal_format": "What was the main goal of the French in colonizing the Americas?", "question_choices": [ "establishing a colony with French subjects", "trading, especially for furs", "gaining control of shipping lanes", "spreading Catholicism among native peoples" ], "question_id": "fs-idm163899552", "question_text": "What was the main goal of the French in colonizing the Americas?" }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 0, "ans_text": "A" }, "bloom": null, "hl_context": "Physical power — to work the fields , build villages , process raw materials — is a necessity for maintaining a society . During the sixteenth and seventeenth centuries , humans could derive power only from the wind , water , animals , or other humans . Everywhere in the Americas , a crushing demand for labor bedeviled Europeans because there were not enough colonists to perform the work necessary to keep the colonies going . <hl> Spain granted encomiendas — legal rights to native labor — to conquistadors who could prove their service to the crown . <hl> This system reflected the Spanish view of colonization : the king rewarded successful conquistadors who expanded the empire . Some native peoples who had sided with the conquistadors , like the Tlaxcalan , also gained encomiendas ; Malintzin , the Nahua woman who helped Cortés defeat the Mexica , was granted one .", "hl_sentences": "Spain granted encomiendas — legal rights to native labor — to conquistadors who could prove their service to the crown .", "question": { "cloze_format": "Spaniards could obtain encomiendas ___", "normal_format": "How could Spaniards obtain encomiendas?", "question_choices": [ "by serving the Spanish crown", "by buying them from other Spaniards", "by buying them from native chiefs", "by inheriting them" ], "question_id": "fs-idp34729504", "question_text": "How could Spaniards obtain encomiendas?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 1, "ans_text": "an exchange of plants, animals, and diseases between Europe and the Americas" }, "bloom": null, "hl_context": "<hl> As Europeans traversed the Atlantic , they brought with them plants , animals , and diseases that changed lives and landscapes on both sides of the ocean . <hl> <hl> These two-way exchanges between the Americas and Europe / Africa are known collectively as the Columbian Exchange ( Figure 2.15 ) . <hl> European promoters of colonization claimed the Americas overflowed with a wealth of treasures . Burnishing national glory and honor became entwined with carving out colonies , and no nation wanted to be left behind . However , the realities of life in the Americas — violence , exploitation , and particularly the need for workers — were soon driving the practice of slavery and forced labor . Everywhere in America a stark contrast existed between freedom and slavery . <hl> The Columbian Exchange , in which Europeans transported plants , animals , and diseases across the Atlantic in both directions , also left a lasting impression on the Americas . <hl>", "hl_sentences": "As Europeans traversed the Atlantic , they brought with them plants , animals , and diseases that changed lives and landscapes on both sides of the ocean . These two-way exchanges between the Americas and Europe / Africa are known collectively as the Columbian Exchange ( Figure 2.15 ) . The Columbian Exchange , in which Europeans transported plants , animals , and diseases across the Atlantic in both directions , also left a lasting impression on the Americas .", "question": { "cloze_format": "The Columbian Exchange is best described by ___", "normal_format": "Which of the following best describes the Columbian Exchange?", "question_choices": [ "the letters Columbus and other conquistadors exchanged with the Spanish crown", "an exchange of plants, animals, and diseases between Europe and the Americas", "a form of trade between the Spanish and natives", "the way in which explorers exchanged information about new lands to conquer" ], "question_id": "fs-idp52988816", "question_text": "Which of the following best describes the Columbian Exchange?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 2, "ans_text": "C" }, "bloom": null, "hl_context": "Travelers between the Americas , Africa , and Europe also included microbes : silent , invisible life forms that had profound and devastating consequences . <hl> Native peoples had no immunity to diseases from across the Atlantic , to which they had never been exposed . <hl> European explorers unwittingly brought with them chickenpox , measles , mumps , and smallpox , which ravaged native peoples despite their attempts to treat the diseases , decimating some populations and wholly destroying others ( Figure 2.16 ) .", "hl_sentences": "Native peoples had no immunity to diseases from across the Atlantic , to which they had never been exposed .", "question": { "cloze_format": "Diseases like smallpox affected Native Americans so badly because ___", "normal_format": "Why did diseases like smallpox affect Native Americans so badly?", "question_choices": [ "Native Americans were less robust than Europeans.", "Europeans deliberately infected Native Americans.", "Native Americans had no immunity to European diseases.", "Conditions in the Americas were so harsh that Native Americans and Europeans alike were devastated by disease." ], "question_id": "fs-idp18402576", "question_text": "Why did diseases like smallpox affect Native Americans so badly?" }, "references_are_paraphrase": 0 } ]
2
2.1 Portuguese Exploration and Spanish Conquest Learning Objectives By the end of this section, you will be able to: Describe Portuguese exploration of the Atlantic and Spanish exploration of the Americas, and the importance of these voyages to the developing Atlantic World Explain the importance of Spanish exploration of the Americas in the expansion of Spain’s empire and the development of Spanish Renaissance culture Portuguese colonization of Atlantic islands in the 1400s inaugurated an era of aggressive European expansion across the Atlantic. In the 1500s, Spain surpassed Portugal as the dominant European power. This age of exploration and the subsequent creation of an Atlantic World marked the earliest phase of globalization , in which previously isolated groups—Africans, Native Americans, and Europeans—first came into contact with each other, sometimes with disastrous results. PORTUGUESE EXPLORATION Portugal’s Prince Henry the Navigator spearheaded his country’s exploration of Africa and the Atlantic in the 1400s. With his support, Portuguese mariners successfully navigated an eastward route to Africa, establishing a foothold there that became a foundation of their nation’s trade empire in the fifteenth and sixteenth centuries. Portuguese mariners built an Atlantic empire by colonizing the Canary, Cape Verde, and Azores Islands, as well as the island of Madeira. Merchants then used these Atlantic outposts as debarkation points for subsequent journeys. From these strategic points, Portugal spread its empire down the western coast of Africa to the Congo, along the western coast of India, and eventually to Brazil on the eastern coast of South America. It also established trading posts in China and Japan. While the Portuguese didn’t rule over an immense landmass, their strategic holdings of islands and coastal ports gave them almost unrivaled control of nautical trade routes and a global empire of trading posts during the 1400s. The travels of Portuguese traders to western Africa introduced them to the African slave trade, already brisk among African states. Seeing the value of this source of labor in growing the profitable crop of sugar on their Atlantic islands, the Portuguese soon began exporting enslaved Africans along with African ivory and gold. Sugar fueled the Atlantic slave trade, and the Portuguese islands quickly became home to sugar plantations. The Portuguese also traded these enslaved people, introducing much-needed human capital to other European nations. In the following years, as European exploration spread, slavery spread as well. In time, much of the Atlantic World would become a gargantuan sugar-plantation complex in which Africans labored to produce the highly profitable commodity for European consumers. Americana Elmina Castle In 1482, Portuguese traders built Elmina Castle (also called São Jorge da Mina, or Saint George’s of the Mine) in present-day Ghana, on the west coast of Africa ( Figure 2.3 ). A fortified trading post, it had mounted cannons facing out to sea, not inland toward continental Africa; the Portuguese had greater fear of a naval attack from other Europeans than of a land attack from Africans. Portuguese traders soon began to settle around the fort and established the town of Elmina. Although the Portuguese originally used the fort primarily for trading gold, by the sixteenth century they had shifted their focus. The dungeon of the fort now served as a holding pen for enslaved Africans from the interior of the continent, while on the upper floors Portuguese traders ate, slept, and prayed in a chapel. Enslaved people lived in the dungeon for weeks or months until ships arrived to transport them to Europe or the Americas. For them, the dungeon of Elmina was their last sight of their home country. SPANISH EXPLORATION AND CONQUEST The Spanish established the first European settlements in the Americas, beginning in the Caribbean and, by 1600, extending throughout Central and South America. Thousands of Spaniards flocked to the Americas seeking wealth and status. The most famous of these Spanish adventurers are Christopher Columbus (who, though Italian himself, explored on behalf of the Spanish monarchs), Hernán Cortés, and Francisco Pizarro. The history of Spanish exploration begins with the history of Spain itself. During the fifteenth century, Spain hoped to gain advantage over its rival, Portugal. The marriage of Ferdinand of Aragon and Isabella of Castile in 1469 unified Catholic Spain and began the process of building a nation that could compete for worldwide power. Since the 700s, much of Spain had been under Islamic rule, and King Ferdinand II and Queen Isabella I, arch-defenders of the Catholic Church against Islam, were determined to defeat the Muslims in Granada, the last Islamic stronghold in Spain. In 1492, they completed the Reconquista: the centuries-long Christian conquest of the Iberian Peninsula. The Reconquista marked another step forward in the process of making Spain an imperial power, and Ferdinand and Isabella were now ready to look further afield. Their goals were to expand Catholicism and to gain a commercial advantage over Portugal. To those ends, Ferdinand and Isabella sponsored extensive Atlantic exploration. Spain’s most famous explorer, Christopher Columbus, was actually from Genoa, Italy. He believed that, using calculations based on other mariners’ journeys, he could chart a westward route to India, which could be used to expand European trade and spread Christianity. Starting in 1485, he approached Genoese, Venetian, Portuguese, English, and Spanish monarchs, asking for ships and funding to explore this westward route. All those he petitioned—including Ferdinand and Isabella at first—rebuffed him; their nautical experts all concurred that Columbus’s estimates of the width of the Atlantic Ocean were far too low. However, after three years of entreaties, and, more important, the completion of the Reconquista, Ferdinand and Isabella agreed to finance Columbus’s expedition in 1492, supplying him with three ships: the Nina , the Pinta , and the Santa Maria . The Spanish monarchs knew that Portuguese mariners had reached the southern tip of Africa and sailed the Indian Ocean. They understood that the Portuguese would soon reach Asia and, in this competitive race to reach the Far East, the Spanish rulers decided to act. Columbus held erroneous views that shaped his thinking about what he would encounter as he sailed west. He believed the earth to be much smaller than its actual size and, since he did not know of the existence of the Americas, he fully expected to land in Asia. On October 12, 1492, however, he made landfall on an island in the Bahamas. He then sailed to an island he named Hispaniola (present-day Dominican Republic and Haiti) ( Figure 2.4 ). Believing he had landed in the East Indies, Columbus called the native Taínos he found there “Indios,” giving rise to the term “Indian” for any native people of the New World. Upon Columbus’s return to Spain, the Spanish crown bestowed on him the title of Admiral of the Ocean Sea and named him governor and viceroy of the lands he had discovered. As a devoted Catholic, Columbus had agreed with Ferdinand and Isabella prior to sailing west that part of the expected wealth from his voyage would be used to continue the fight against Islam. Columbus’s 1493 letter—or probanza de mérito (proof of merit)—describing his “discovery” of a New World did much to inspire excitement in Europe. Probanzas de méritos were reports and letters written by Spaniards in the New World to the Spanish crown, designed to win royal patronage. Today they highlight the difficult task of historical work; while the letters are primary sources, historians need to understand the context and the culture in which the conquistadors, as the Spanish adventurers came to be called, wrote them and distinguish their bias and subjective nature. While they are filled with distortions and fabrications, probanzas de méritos are still useful in illustrating the expectation of wealth among the explorers as well as their view that native peoples would not pose a serious obstacle to colonization. In 1493, Columbus sent two copies of a probanza de mérito to the Spanish king and queen and their minister of finance, Luis de Santángel. Santángel had supported Columbus’s voyage, helping him to obtain funding from Ferdinand and Isabella. Copies of the letter were soon circulating all over Europe, spreading news of the wondrous new land that Columbus had “discovered.” Columbus would make three more voyages over the next decade, establishing Spain’s first settlement in the New World on the island of Hispaniola. Many other Europeans followed in Columbus’s footsteps, drawn by dreams of winning wealth by sailing west. Another Italian, Amerigo Vespucci, sailing for the Portuguese crown, explored the South American coastline between 1499 and 1502. Unlike Columbus, he realized that the Americas were not part of Asia but lands unknown to Europeans. Vespucci’s widely published accounts of his voyages fueled speculation and intense interest in the New World among Europeans. Among those who read Vespucci’s reports was the German mapmaker Martin Waldseemuller. Using the explorer’s first name as a label for the new landmass, Waldseemuller attached “America” to his map of the New World in 1507, and the name stuck. Defining American Columbus’s Probanza de mérito of 1493 The exploits of the most famous Spanish explorers have provided Western civilization with a narrative of European supremacy and Native American savagery. However, these stories are based on the self-aggrandizing efforts of conquistadors to secure royal favor through the writing of probanzas de méritos (proofs of merit). Below are excerpts from Columbus’s 1493 letter to Luis de Santángel, which illustrates how fantastic reports from European explorers gave rise to many myths surrounding the Spanish conquest and the New World. This island, like all the others, is most extensive. It has many ports along the sea-coast excelling any in Christendom—and many fine, large, flowing rivers. The land there is elevated, with many mountains and peaks incomparably higher than in the centre isle. They are most beautiful, of a thousand varied forms, accessible, and full of trees of endless varieties, so high that they seem to touch the sky, and I have been told that they never lose their foliage. . . . There is honey, and there are many kinds of birds, and a great variety of fruits. Inland there are numerous mines of metals and innumerable people. Hispaniola is a marvel. Its hills and mountains, fine plains and open country, are rich and fertile for planting and for pasturage, and for building towns and villages. The seaports there are incredibly fine, as also the magnificent rivers, most of which bear gold. The trees, fruits and grasses differ widely from those in Juana. There are many spices and vast mines of gold and other metals in this island. They have no iron, nor steel, nor weapons, nor are they fit for them, because although they are well-made men of commanding stature, they appear extraordinarily timid. The only arms they have are sticks of cane, cut when in seed, with a sharpened stick at the end, and they are afraid to use these. Often I have sent two or three men ashore to some town to converse with them, and the natives came out in great numbers, and as soon as they saw our men arrive, fled without a moment’s delay although I protected them from all injury. What does this letter show us about Spanish objectives in the New World? How do you think it might have influenced Europeans reading about the New World for the first time? The 1492 Columbus landfall accelerated the rivalry between Spain and Portugal, and the two powers vied for domination through the acquisition of new lands. In the 1480s, Pope Sixtus IV had granted Portugal the right to all land south of the Cape Verde islands, leading the Portuguese king to claim that the lands discovered by Columbus belonged to Portugal, not Spain. Seeking to ensure that Columbus’s finds would remain Spanish, Spain’s monarchs turned to the Spanish-born Pope Alexander VI, who issued two papal decrees in 1493 that gave legitimacy to Spain’s Atlantic claims at the expense of Portugal. Hoping to salvage Portugal’s Atlantic holdings, King João II began negotiations with Spain. The resulting Treaty of Tordesillas in 1494 drew a north-to-south line through South America ( Figure 2.5 ); Spain gained territory west of the line, while Portugal retained the lands east of the line, including the east coast of Brazil. Columbus’s discovery opened a floodgate of Spanish exploration. Inspired by tales of rivers of gold and timid, malleable natives, later Spanish explorers were relentless in their quest for land and gold. Hernán Cortés hoped to gain hereditary privilege for his family, tribute payments and labor from natives, and an annual pension for his service to the crown. Cortés arrived on Hispaniola in 1504 and took part in the conquest of that island. In anticipation of winning his own honor and riches, Cortés later explored the Yucatán Peninsula. In 1519, he entered Tenochtitlán, the capital of the Aztec (Mexica) Empire. He and his men were astonished by the incredibly sophisticated causeways, gardens, and temples in the city, but they were horrified by the practice of human sacrifice that was part of the Aztec religion. Above all else, the Aztec wealth in gold fascinated the Spanish adventurers. Hoping to gain power over the city, Cortés took Moctezuma, the Aztec ruler, hostage. The Spanish then murdered hundreds of high-ranking Mexica during a festival to celebrate Huitzilopochtli, the god of war. This angered the people of Tenochtitlán, who rose up against the interlopers in their city. Cortés and his people fled for their lives, running down one of Tenochtitlán’s causeways to safety on the shore. Smarting from their defeat at the hands of the Aztec, Cortés slowly created alliances with native peoples who resented Aztec rule. It took nearly a year for the Spanish and the tens of thousands of native allies who joined them to defeat the Mexica in Tenochtitlán, which they did by laying siege to the city. Only by playing upon the disunity among the diverse groups in the Aztec Empire were the Spanish able to capture the grand city of Tenochtitlán. In August 1521, having successfully fomented civil war as well as fended off rival Spanish explorers, Cortés claimed Tenochtitlán for Spain and renamed it Mexico City. The traditional European narrative of exploration presents the victory of the Spanish over the Aztec as an example of the superiority of the Europeans over the "savage Indians." However, the reality is far more complex. When Cortés explored central Mexico, he encountered a region simmering with conflict. Far from being unified and content under Aztec rule, many peoples in Mexico resented it and were ready to rebel. One group in particular, the Tlaxcalan, threw their lot in with the Spanish, providing as many as 200,000 fighters in the siege of Tenochtitlán. The Spanish also brought smallpox into the valley of Mexico. The disease took a heavy toll on the people in Tenochtitlán, playing a much greater role in the city’s demise than did Spanish force of arms. Cortés was also aided by a Nahua woman called Malintzin (also known as La Malinche or Doña Marina, her Spanish name), whom the natives of Tabasco gave him as tribute. Malintzin translated for Cortés in his dealings with Moctezuma and, whether willingly or under pressure, entered into a physical relationship with him. Their son, Martín, may have been the first mestizo (person of mixed indigenous American and European descent). Malintzin remains a controversial figure in the history of the Atlantic World; some people view her as a traitor because she helped Cortés conquer the Aztecs, while others see her as a victim of European expansion. In either case, she demonstrates one way in which native peoples responded to the arrival of the Spanish. Without her, Cortés would not have been able to communicate, and without the language bridge, he surely would have been less successful in destabilizing the Aztec Empire. By this and other means, native people helped shape the conquest of the Americas. Spain’s acquisitiveness seemingly knew no bounds as groups of its explorers searched for the next trove of instant riches. One such explorer, Francisco Pizarro, made his way to the Spanish Caribbean in 1509, drawn by the promise of wealth and titles. He participated in successful expeditions in Panama before following rumors of Inca wealth to the south. Although his first efforts against the Inca Empire in the 1520s failed, Pizarro captured the Inca emperor Atahualpa in 1532 and executed him one year later. In 1533, Pizarro founded Lima, Peru. Like Cortés, Pizarro had to combat not only the natives of the new worlds he was conquering, but also competitors from his own country; a Spanish rival assassinated him in 1541. Spain’s drive to enlarge its empire led other hopeful conquistadors to push further into the Americas, hoping to replicate the success of Cortés and Pizarro. Hernando de Soto had participated in Pizarro’s conquest of the Inca, and from 1539 to 1542 he led expeditions to what is today the southeastern United States, looking for gold. He and his followers explored what is now Florida, Georgia, the Carolinas, Tennessee, Alabama, Mississippi, Arkansas, Oklahoma, Louisiana, and Texas. Everywhere they traveled, they brought European diseases, which claimed thousands of native lives as well as the lives of the explorers. In 1542, de Soto himself died during the expedition. The surviving Spaniards, numbering a little over three hundred, returned to Mexico City without finding the much-anticipated mountains of gold and silver. Francisco Vásquez de Coronado was born into a noble family and went to Mexico, then called New Spain, in 1535. He presided as governor over the province of Nueva Galicia, where he heard rumors of wealth to the north: a golden city called Quivira. Between 1540 and 1542, Coronado led a large expedition of Spaniards and native allies to the lands north of Mexico City, and for the next several years, they explored the area that is now the southwestern United States ( Figure 2.6 ). During the winter of 1540–41, the explorers waged war against the Tiwa in present-day New Mexico. Rather than leading to the discovery of gold and silver, however, the expedition simply left Coronado bankrupt. THE SPANISH GOLDEN AGE The exploits of European explorers had a profound impact both in the Americas and back in Europe. An exchange of ideas, fueled and financed in part by New World commodities, began to connect European nations and, in turn, to touch the parts of the world that Europeans conquered. In Spain, gold and silver from the Americas helped to fuel a golden age, the Siglo de Oro, when Spanish art and literature flourished. Riches poured in from the colonies, and new ideas poured in from other countries and new lands. The Hapsburg dynasty, which ruled a collection of territories including Austria, the Netherlands, Naples, Sicily, and Spain, encouraged and financed the work of painters, sculptors, musicians, architects, and writers, resulting in a blooming of Spanish Renaissance culture. One of this period’s most famous works is the novel The Ingenious Gentleman Don Quixote of La Mancha , by Miguel de Cervantes. This two-volume book (1605 and 1618) told a colorful tale of an hidalgo (gentleman) who reads so many tales of chivalry and knighthood that he becomes unable to tell reality from fiction. With his faithful sidekick Sancho Panza, Don Quixote leaves reality behind and sets out to revive chivalry by doing battle with what he perceives as the enemies of Spain. Spain attracted innovative foreign painters such as El Greco, a Greek who had studied with Italian Renaissance masters like Titian and Michelangelo before moving to Toledo. Native Spaniards created equally enduring works. Las Meninas (The Maids of Honor) , painted by Diego Velázquez in 1656, is one of the best-known paintings in history. Velázquez painted himself into this imposingly large royal portrait (he’s shown holding his brush and easel on the left) and boldly placed the viewer where the king and queen would stand in the scene ( Figure 2.7 ). 2.2 Religious Upheavals in the Developing Atlantic World Learning Objectives By the end of this section, you will be able to: Explain the changes brought by the Protestant Reformation and how it influenced the development of the Atlantic World Describe Spain’s response to the Protestant Reformation Until the 1500s, the Catholic Church provided a unifying religious structure for Christian Europe. The Vatican in Rome exercised great power over the lives of Europeans; it controlled not only learning and scholarship but also finances, because it levied taxes on the faithful. Spain, with its New World wealth, was the bastion of the Catholic faith. Beginning with the reform efforts of Martin Luther in 1517 and John Calvin in the 1530s, however, Catholic dominance came under attack as the Protestant Reformation , a split or schism among European Christians, began. During the sixteenth century, Protestantism spread through northern Europe, and Catholic countries responded by attempting to extinguish what was seen as the Protestant menace. Religious turmoil between Catholics and Protestants influenced the history of the Atlantic World as well, since different nation-states competed not only for control of new territories but also for the preeminence of their religious beliefs there. Just as the history of Spain’s rise to power is linked to the Reconquista, so too is the history of early globalization connected to the history of competing Christian groups in the Atlantic World. MARTIN LUTHER Martin Luther ( Figure 2.8 ) was a German Catholic monk who took issue with the Catholic Church’s practice of selling indulgences , documents that absolved sinners of their errant behavior. He also objected to the Catholic Church’s taxation of ordinary Germans and the delivery of Mass in Latin, arguing that it failed to instruct German Catholics, who did not understand the language. Many Europeans had called for reforms of the Catholic Church before Martin Luther did, but his protest had the unintended consequence of splitting European Christianity. Luther compiled a list of what he viewed as needed Church reforms, a document that came to be known as The Ninety-Five Theses , and nailed it to the door of a church in Wittenberg, Germany, in 1517. He called for the publication of the Bible in everyday language, took issue with the Church’s policy of imposing tithes (a required payment to the Church that appeared to enrich the clergy), and denounced the buying and selling of indulgences. Although he had hoped to reform the Catholic Church while remaining a part of it, Luther’s action instead triggered a movement called the Protestant Reformation that divided the Church in two. The Catholic Church condemned him as a heretic, but a doctrine based on his reforms, called Lutheranism, spread through northern Germany and Scandinavia. JOHN CALVIN Like Luther, the French lawyer John Calvin advocated making the Bible accessible to ordinary people; only by reading scripture and reflecting daily about their spiritual condition, he argued, could believers begin to understand the power of God. In 1535, Calvin fled Catholic France and led the Reformation movement from Geneva, Switzerland. Calvinism emphasized human powerlessness before an omniscient God and stressed the idea of predestination, the belief that God selected a few chosen people for salvation while everyone else was predestined to damnation. Calvinists believed that reading scripture prepared sinners, if they were among the elect, to receive God’s grace. In Geneva, Calvin established a Bible commonwealth, a community of believers whose sole source of authority was their interpretation of the Bible, not the authority of any prince or monarch. Soon Calvin’s ideas spread to the Netherlands and Scotland. PROTESTANTISM IN ENGLAND Protestantism spread beyond the German states and Geneva to England, which had been a Catholic nation for centuries. Luther’s idea that scripture should be available in the everyday language of worshippers inspired English scholar William Tyndale to translate the Bible into English in 1526. The seismic break with the Catholic Church in England occurred in the 1530s, when Henry VIII established a new, Protestant state religion. A devout Catholic, Henry had initially stood in opposition to the Reformation. Pope Leo X even awarded him the title “Defender of the Faith.” The tides turned, however, when Henry desired a male heir to the Tudor monarchy. When his Spanish Catholic wife, Catherine (the daughter of Ferdinand and Isabella), did not give birth to a boy, the king sought an annulment to their marriage. When the Pope refused his request, Henry created a new national Protestant church, the Church of England, with himself at its head. This left him free to annul his own marriage and marry Anne Boleyn. Anne Boleyn also failed to produce a male heir, and when she was accused of adultery, Henry had her executed. His third wife, Jane Seymour, at long last delivered a son, Edward, who ruled for only a short time before dying in 1553 at the age of fifteen. Mary, the daughter of Henry VIII and his discarded first wife Catherine, then came to the throne, committed to restoring Catholicism. She earned the nickname “Bloody Mary” for the many executions of Protestants, often by burning alive, that she ordered during her reign. Religious turbulence in England was finally quieted when Elizabeth, the Protestant daughter of Henry VIII and Anne Boleyn, ascended the throne in 1558. Under Elizabeth, the Church of England again became the state church, retaining the hierarchical structure and many of the rituals of the Catholic Church. However, by the late 1500s, some English members of the Church began to agitate for more reform. Known as Puritans , they worked to erase all vestiges of Catholicism from the Church of England. At the time, the term “puritan” was a pejorative one; many people saw Puritans as holier-than-thou frauds who used religion to swindle their neighbors. Worse still, many in power saw Puritans as a security threat because of their opposition to the national church. Under Elizabeth, whose long reign lasted from 1558 to 1603, Puritans grew steadily in number. After James I died in 1625 and his son Charles I ascended the throne, Puritans became the target of increasing state pressure to conform. Many crossed the Atlantic in the 1620s and 1630s instead to create a New England, a haven for reformed Protestantism where Puritan was no longer a term of abuse. Thus, the religious upheavals that affected England so much had equally momentous consequences for the Americas. RELIGIOUS WAR By the early 1500s, the Protestant Reformation threatened the massive Spanish Catholic empire. As the preeminent Catholic power, Spain would not tolerate any challenge to the Holy Catholic Church. Over the course of the 1500s, it devoted vast amounts of treasure and labor to leading an unsuccessful effort to eradicate Protestantism in Europe. Spain’s main enemies at this time were the runaway Spanish provinces of the North Netherlands. By 1581, these seven northern provinces had declared their independence from Spain and created the Dutch Republic, also called Holland, where Protestantism was tolerated. Determined to deal a death blow to Protestantism in England and Holland, King Philip of Spain assembled a massive force of over thirty thousand men and 130 ships, and in 1588 he sent this navy, the Spanish Armada, north. But English sea power combined with a maritime storm destroyed the fleet. The defeat of the Spanish Armada in 1588 was but one part of a larger but undeclared war between Protestant England and Catholic Spain. Between 1585 and 1604, the two rivals sparred repeatedly. England launched its own armada in 1589 in an effort to cripple the Spanish fleet and capture Spanish treasure. However, the foray ended in disaster for the English, with storms, disease, and the strength of the Spanish Armada combining to bring about defeat. The conflict between Spain and England dragged on into the early seventeenth century, and the newly Protestant nations, especially England and the Dutch Republic, posed a significant challenge to Spain (and also to Catholic France) as imperial rivalries played out in the Atlantic World. Spain retained its mighty American empire, but by the early 1600s, the nation could no longer keep England and other European rivals—the French and Dutch—from colonizing smaller islands in the Caribbean ( Figure 2.9 ). Religious intolerance characterized the sixteenth and seventeenth centuries, an age of powerful state religions with the authority to impose and enforce belief systems on the population. In this climate, religious violence was common. One of the most striking examples is the St. Bartholomew’s Day Massacre of 1572, in which French Catholic troops began to kill unarmed French Protestants ( Figure 2.10 ). The murders touched off mob violence that ultimately claimed nine thousand lives, a bloody episode that highlights the degree of religious turmoil that gripped Europe in the aftermath of the Protestant Reformation. 2.3 Challenges to Spain’s Supremacy Learning Objectives By the end of this section, you will be able to: Identify regions where the English, French, and Dutch explored and established settlements Describe the differences among the early colonies Explain the role of the American colonies in European nations’ struggles for domination For Europeans, the discovery of an Atlantic World meant newfound wealth in the form of gold and silver as well as valuable furs. The Americas also provided a new arena for intense imperial rivalry as different European nations jockeyed for preeminence in the New World. The religious motives for colonization spurred European expansion as well, and as the Protestant Reformation gained ground beginning in the 1520s, rivalries between Catholic and Protestant Christians spilled over into the Americas. ENGLISH EXPLORATION Disruptions during the Tudor monarchy—especially the creation of the Protestant Church of England by Henry VIII in the 1530s, the return of the nation to Catholicism under Queen Mary in the 1550s, and the restoration of Protestantism under Queen Elizabeth—left England with little energy for overseas projects. More important, England lacked the financial resources for such endeavors. Nonetheless, English monarchs carefully monitored developments in the new Atlantic World and took steps to assert England’s claim to the Americas. As early as 1497, Henry VII of England had commissioned John Cabot, an Italian mariner, to explore new lands. Cabot sailed from England that year and made landfall somewhere along the North American coastline. For the next century, English fishermen routinely crossed the Atlantic to fish the rich waters off the North American coast. However, English colonization efforts in the 1500s were closer to home, as England devoted its energy to the colonization of Ireland. Queen Elizabeth favored England’s advance into the Atlantic World, though her main concern was blocking Spain’s effort to eliminate Protestantism. Indeed, England could not commit to large-scale colonization in the Americas as long as Spain appeared ready to invade Ireland or Scotland. Nonetheless, Elizabeth approved of English privateers , sea captains to whom the home government had given permission to raid the enemy at will. These skilled mariners cruised the Caribbean, plundering Spanish ships whenever they could. Each year the English took more than £100,000 from Spain in this way; English privateer Francis Drake first made a name for himself when, in 1573, he looted silver, gold, and pearls worth £40,000. Elizabeth did sanction an early attempt at colonization in 1584, when Sir Walter Raleigh, a favorite of the queen’s, attempted to establish a colony at Roanoke , an island off the coast of present-day North Carolina. The colony was small, consisting of only 117 people, who suffered a poor relationship with the local Croatans, and struggled to survive in their new land ( Figure 2.11 ). Their governor, John White, returned to England in late 1587 to secure more people and supplies, but events conspired to keep him away from Roanoke for three years. By the time he returned in 1590, the entire colony had vanished. The only trace the colonists left behind was the word Croatoan carved into a fence surrounding the village. Governor White never knew whether the colonists had decamped for nearby Croatoan Island (now Hatteras) or whether some disaster had befallen them all. Roanoke is still called “the lost colony.” English promoters of colonization pushed its commercial advantages and the religious justification that English colonies would allow the establishment of Protestantism in the Americas. Both arguments struck a chord. In the early 1600s, wealthy English merchants and the landed elite began to pool their resources to form joint stock companies . In this novel business arrangement, which was in many ways the precursor to the modern corporation, investors provided the capital for and assumed the risk of a venture in order to reap significant returns. The companies gained the approval of the English crown to establish colonies, and their investors dreamed of reaping great profits from the money they put into overseas colonization. The first permanent English settlement was established by a joint stock company, the Virginia Company. Named for Elizabeth, the “virgin queen,” the company gained royal approval to establish a colony on the east coast of North America, and in 1606, it sent 144 men and boys to the New World. In early 1607, this group sailed up Chesapeake Bay. Finding a river they called the James in honor of their new king, James I, they established a ramshackle settlement and named it Jamestown. Despite serious struggles, the colony survived. Many of Jamestown’s settlers were desperate men; although they came from elite families, they were younger sons who would not inherit their father’s estates. The Jamestown adventurers believed they would find instant wealth in the New World and did not actually expect to have to perform work. Henry Percy, the eighth son of the Earl of Northumberland, was among them. His account, excerpted below, illustrates the hardships the English confronted in Virginia in 1607. My Story George Percy and the First Months at Jamestown The 144 men and boys who started the Jamestown colony faced many hardships; by the end of the first winter, only 38 had survived. Disease, hunger, and poor relationships with local natives all contributed to the colony’s high death toll. George Percy, who served twice as governor of Jamestown, kept records of the colonists’ first months in the colony. These records were later published in London in 1608. This excerpt is from his account of August and September of 1607. The fourth day of September died Thomas Jacob Sergeant. The fifth day, there died Benjamin Beast. Our men were destroyed with cruel diseases, as Swellings, Fluxes, Burning Fevers, and by wars, and some departed suddenly, but for the most part they died of mere famine. There were never Englishmen left in a foreign Country in such misery as we were in this new discovered Virginia. . . . Our food was but a small Can of Barley sod* in water, to five men a day, our drink cold water taken out of the River, which was at a flood very salty, at a low tide full of slime and filth, which was the destruction of many of our men. Thus we lived for the space of five months in this miserable distress, not having five able men to man our Bulwarks upon any occasion. If it had not pleased God to have put a terror in the Savages’ hearts, we had all perished by those wild and cruel Pagans, being in that weak estate as we were; our men night and day groaning in every corner of the Fort most pitiful to hear. If there were any conscience in men, it would make their hearts to bleed to hear the pitiful murmurings and outcries of our sick men without relief, every night and day, for the space of six weeks, some departing out of the World, many times three or four in a night; in the morning, their bodies trailed out of their Cabins like Dogs to be buried. In this sort did I see the mortality of diverse of our people. *soaked According to George Percy’s account, what were the major problems the Jamestown settlers encountered? What kept the colony from complete destruction? By any measure, England came late to the race to colonize. As Jamestown limped along in the 1610s, the Spanish Empire extended around the globe and grew rich from its global colonial project. Yet the English persisted, and for this reason the Jamestown settlement has a special place in history as the first permanent English colony in what later became the United States. After Jamestown’s founding, English colonization of the New World accelerated. In 1609, a ship bound for Jamestown foundered in a storm and landed on Bermuda. (Some believe this incident helped inspire Shakespeare’s 1611 play The Tempest .) The admiral of the ship, George Somers, claimed the island for the English crown. The English also began to colonize small islands in the Caribbean, an incursion into the Spanish American empire. They established themselves on small islands such as St. Christopher (1624), Barbados (1627), Nevis (1628), Montserrat (1632), and Antigua (1632). From the start, the English West Indies had a commercial orientation, for these islands produced cash crops: first tobacco and then sugar. Very quickly, by the mid-1600s, Barbados had become one of the most important English colonies because of the sugar produced there. Barbados was the first English colony dependent on enslaved people, and it became a model for other English slave societies on the American mainland. These differed radically from England itself, where slavery was not practiced. English Puritans also began to colonize the Americas in the 1620s and 1630s. These intensely religious migrants dreamed of creating communities of reformed Protestantism where the corruption of England would be eliminated. One of the first groups of Puritans to move to North America, known as Pilgrims and led by William Bradford, had originally left England to live in the Netherlands. Fearing their children were losing their English identity among the Dutch, however, they sailed for North America in 1620 to settle at Plymouth, the first English settlement in New England. The Pilgrims differed from other Puritans in their insistence on separating from what they saw as the corrupt Church of England. For this reason, Pilgrims are known as Separatists . Like Jamestown, Plymouth occupies an iconic place in American national memory. The tale of the 102 migrants who crossed the Atlantic aboard the Mayflower and their struggle for survival is a well-known narrative of the founding of the country. Their story includes the signing of the Mayflower Compact, a written agreement whereby the English voluntarily agreed to help each other. Some interpret this 1620 document as an expression of democratic spirit because of the cooperative and inclusive nature of the agreement to live and work together. In 1630, a much larger contingent of Puritans left England to escape conformity to the Church of England and founded the Massachusetts Bay Colony. In the following years, thousands more arrived to create a new life in the rocky soils and cold climates of New England. In comparison to Catholic Spain, however, Protestant England remained a very weak imperial player in the early seventeenth century, with only a few infant colonies in the Americas in the early 1600s. The English never found treasure equal to that of the Aztec city of Tenochtitlán, and England did not quickly grow rich from its small American outposts. The English colonies also differed from each other; Barbados and Virginia had a decidedly commercial orientation from the start, while the Puritan colonies of New England were intensely religious at their inception. All English settlements in America, however, marked the increasingly important role of England in the Atlantic World. FRENCH EXPLORATION Spanish exploits in the New World whetted the appetite of other would-be imperial powers, including France. Like Spain, France was a Catholic nation and committed to expanding Catholicism around the globe. In the early sixteenth century, it joined the race to explore the New World and exploit the resources of the Western Hemisphere. Navigator Jacques Cartier claimed northern North America for France, naming the area New France. From 1534 to 1541, he made three voyages of discovery on the Gulf of St. Lawrence and the St. Lawrence River. Like other explorers, Cartier made exaggerated claims of mineral wealth in America, but he was unable to send great riches back to France. Due to resistance from the native peoples as well as his own lack of planning, he could not establish a permanent settlement in North America. Explorer Samuel de Champlain occupies a special place in the history of the Atlantic World for his role in establishing the French presence in the New World. Champlain explored the Caribbean in 1601 and then the coast of New England in 1603 before traveling farther north. In 1608 he founded Quebec, and he made numerous Atlantic crossings as he worked tirelessly to promote New France. Unlike other imperial powers, France—through Champlain’s efforts—fostered especially good relationships with native peoples, paving the way for French exploration further into the continent: around the Great Lakes, around Hudson Bay, and eventually to the Mississippi. Champlain made an alliance with the Huron confederacy and the Algonquins and agreed to fight with them against their enemy, the Iroquois ( Figure 2.12 ). The French were primarily interested in establishing commercially viable colonial outposts, and to that end, they created extensive trading networks in New France. These networks relied on native hunters to harvest furs, especially beaver pelts, and to exchange these items for French glass beads and other trade goods. (French fashion at the time favored broad-brimmed hats trimmed in beaver fur, so French traders had a ready market for their North American goods.) The French also dreamed of replicating the wealth of Spain by colonizing the tropical zones. After Spanish control of the Caribbean began to weaken, the French turned their attention to small islands in the West Indies, and by 1635 they had colonized two, Guadeloupe and Martinique. Though it lagged far behind Spain, France now boasted its own West Indian colonies. Both islands became lucrative sugar plantation sites that turned a profit for French planters by relying on African slave labor. DUTCH COLONIZATION Dutch entrance into the Atlantic World is part of the larger story of religious and imperial conflict in the early modern era. In the 1500s, Calvinism, one of the major Protestant reform movements, had found adherents in the northern provinces of the Spanish Netherlands. During the sixteenth century, these provinces began a long struggle to achieve independence from Catholic Spain. Established in 1581 but not recognized as independent by Spain until 1648, the Dutch Republic, or Holland, quickly made itself a powerful force in the race for Atlantic colonies and wealth. The Dutch distinguished themselves as commercial leaders in the seventeenth century ( Figure 2.13 ), and their mode of colonization relied on powerful corporations: the Dutch East India Company, chartered in 1602 to trade in Asia, and the Dutch West India Company, established in 1621 to colonize and trade in the Americas. While employed by the Dutch East India Company in 1609, the English sea captain Henry Hudson explored New York Harbor and the river that now bears his name. Like many explorers of the time, Hudson was actually seeking a northwest passage to Asia and its wealth, but the ample furs harvested from the region he explored, especially the coveted beaver pelts, provided a reason to claim it for the Netherlands. The Dutch named their colony New Netherlands, and it served as a fur-trading outpost for the expanding and powerful Dutch West India Company. With headquarters in New Amsterdam on the island of Manhattan, the Dutch set up several regional trading posts, including one at Fort Orange—named for the royal Dutch House of Orange-Nassau—in present-day Albany. (The color orange remains significant to the Dutch, having become particularly associated with William of Orange, Protestantism, and the Glorious Revolution of 1688.) A brisk trade in furs with local Algonquian and Iroquois peoples brought the Dutch and native peoples together in a commercial network that extended throughout the Hudson River Valley and beyond. The Dutch West India Company in turn established colonies on Aruba, Bonaire, and Curaçao, St. Martin, St. Eustatius, and Saba. With their outposts in New Netherlands and the Caribbean, the Dutch had established themselves in the seventeenth century as a commercially powerful rival to Spain. Amsterdam became a trade hub for all the Atlantic World. 2.4 New Worlds in the Americas: Labor, Commerce, and the Columbian Exchange Learning Objectives By the end of this section, you will be able to: Describe how Europeans solved their labor problems Describe the theory of mercantilism and the process of commodification Analyze the effects of the Columbian Exchange European promoters of colonization claimed the Americas overflowed with a wealth of treasures. Burnishing national glory and honor became entwined with carving out colonies, and no nation wanted to be left behind. However, the realities of life in the Americas—violence, exploitation, and particularly the need for workers—were soon driving the practice of slavery and forced labor. Everywhere in America a stark contrast existed between freedom and slavery. The Columbian Exchange, in which Europeans transported plants, animals, and diseases across the Atlantic in both directions, also left a lasting impression on the Americas. LABOR SYSTEMS Physical power—to work the fields, build villages, process raw materials—is a necessity for maintaining a society. During the sixteenth and seventeenth centuries, humans could derive power only from the wind, water, animals, or other humans. Everywhere in the Americas, a crushing demand for labor bedeviled Europeans because there were not enough colonists to perform the work necessary to keep the colonies going. Spain granted encomiendas —legal rights to native labor—to conquistadors who could prove their service to the crown. This system reflected the Spanish view of colonization: the king rewarded successful conquistadors who expanded the empire. Some native peoples who had sided with the conquistadors, like the Tlaxcalan, also gained encomiendas ; Malintzin, the Nahua woman who helped Cortés defeat the Mexica, was granted one. The Spanish believed native peoples would work for them by right of conquest, and, in return, the Spanish would bring them Catholicism. In theory the relationship consisted of reciprocal obligations, but in practice the Spaniards ruthlessly exploited it, seeing native people as little more than beasts of burden. Convinced of their right to the land and its peoples, they sought both to control native labor and to impose what they viewed as correct religious beliefs upon the land’s inhabitants. Native peoples everywhere resisted both the labor obligations and the effort to change their ancient belief systems. Indeed, many retained their religion or incorporated only the parts of Catholicism that made sense to them. The system of encomiendas was accompanied by a great deal of violence ( Figure 2.14 ). One Spaniard, Bartolomé de Las Casas, denounced the brutality of Spanish rule. A Dominican friar, Las Casas had been one of the earliest Spanish settlers in the Spanish West Indies. In his early life in the Americas, he enslaved Native people and was the recipient of an encomienda . However, after witnessing the savagery with which encomenderos (recipients of encomiendas ) treated the native people, he reversed his views. In 1515, Las Casas released his enslaved natives, gave up his encomienda , and began to advocate for humane treatment of native peoples. He lobbied for new legislation, eventually known as the New Laws, which would eliminate slavery and the encomienda system. Las Casas’s writing about the Spaniards’ horrific treatment of Native people helped inspire the so-called Black Legend , the idea that the Spanish were bloodthirsty conquerors with no regard for human life. Perhaps not surprisingly, those who held this view of the Spanish were Spain’s imperial rivals. English writers and others seized on the idea of Spain’s ruthlessness to support their own colonization projects. By demonizing the Spanish, they justified their own efforts as more humane. All European colonizers, however, shared a disregard for Native peoples. My Story Bartolomé de Las Casas on the Mistreatment of Native Peoples Bartolomé de Las Casas’s A Short Account of the Destruction of the Indies , written in 1542 and published ten years later, detailed for Prince Philip II of Spain how Spanish colonists had been mistreating natives. Into and among these gentle sheep, endowed by their Maker and Creator with all the qualities aforesaid, did creep the Spaniards, who no sooner had knowledge of these people than they became like fierce wolves and tigers and lions who have gone many days without food or nourishment. And no other thing have they done for forty years until this day, and still today see fit to do, but dismember, slay, perturb, afflict, torment, and destroy the Native Americans by all manner of cruelty—new and divers and most singular manners such as never before seen or read or heard of—some few of which shall be recounted below, and they do this to such a degree that on the Island of Hispaniola, of the above three millions souls that we once saw, today there be no more than two hundred of those native people remaining. . . . Two principal and general customs have been employed by those, calling themselves Christians, who have passed this way, in extirpating and striking from the face of the earth those suffering nations. The first being unjust, cruel, bloody, and tyrannical warfare. The other—after having slain all those who might yearn toward or suspire after or think of freedom, or consider escaping from the torments that they are made to suffer, by which I mean all the native-born lords and adult males, for it is the Spaniards’ custom in their wars to allow only young boys and females to live—being to oppress them with the hardest, harshest, and most heinous bondage to which men or beasts might ever be bound into. How might these writings have been used to promote the “black legend” against Spain as well as subsequent English exploration and colonization? Native peoples were not the only source of cheap labor in the Americas; by the middle of the sixteenth century, Africans formed an important element of the labor landscape, producing the cash crops of sugar and tobacco for European markets. Europeans viewed Africans as non-Christians, which they used as a justification for enslavement. Denied control over their lives, enslaved people endured horrendous conditions. At every opportunity, they resisted enslavement, and their resistance was met with violence. Indeed, physical, mental, and sexual violence formed a key strategy among European slaveholders in their effort to assert mastery and impose their will. The Portuguese led the way in the evolving transport of captive enslaved people across the Atlantic; slave “factories” on the west coast of Africa, like Elmina Castle in Ghana, served as holding pens for enslaved people brought from Africa’s interior. In time, other European imperial powers would follow in the footsteps of the Portuguese by constructing similar outposts on the coast of West Africa. The Portuguese traded or sold enslaved people to Spanish, Dutch, and English colonists in the Americas, particularly in South America and the Caribbean, where sugar was a primary export. Thousands of enslaved Africans found themselves growing, harvesting, and processing sugarcane in an arduous routine of physical labor. Enslaved people had to cut the long cane stalks by hand and then bring them to a mill, where the cane juice was extracted. They boiled the extracted cane juice down to a brown, crystalline sugar, which then had to be cured in special curing houses to have the molasses drained from it. The result was refined sugar, while the leftover molasses could be distilled into rum. Every step was labor-intensive and often dangerous. Las Casas estimated that by 1550, there were fifty thousand enslaved people on Hispaniola. However, it is a mistake to assume that during the very early years of European exploration all Africans came to America as captives; some were free men who took part in expeditions, for example, serving as conquistadors alongside Cortés in his assault on Tenochtitlán. Nonetheless, African slavery was one of the most tragic outcomes in the emerging Atlantic World. COMMERCE IN THE NEW WORLD The economic philosophy of mercantilism shaped European perceptions of wealth from the 1500s to the late 1700s. Mercantilism held that only a limited amount of wealth, as measured in gold and silver bullion, existed in the world. In order to gain power, nations had to amass wealth by mining these precious raw materials from their colonial possessions. During the age of European exploration, nations employed conquest, colonization, and trade as ways to increase their share of the bounty of the New World. Mercantilists did not believe in free trade, arguing instead that the nation should control trade to create wealth. In this view, colonies existed to strengthen the colonizing nation. Mercantilists argued against allowing their nations to trade freely with other nations. Spain’s mercantilist ideas guided its economic policy. Every year, enslaved laborers or native workers loaded shipments of gold and silver aboard Spanish treasure fleets that sailed from Cuba for Spain. These ships groaned under the sheer weight of bullion, for the Spanish had found huge caches of silver and gold in the New World. In South America, for example, Spaniards discovered rich veins of silver ore in the mountain called Potosí and founded a settlement of the same name there. Throughout the sixteenth century, Potosí was a boom town, attracting settlers from many nations as well as native people from many different cultures. Colonial mercantilism, which was basically a set of protectionist policies designed to benefit the nation, relied on several factors: colonies rich in raw materials, cheap labor, colonial loyalty to the home government, and control of the shipping trade. Under this system, the colonies sent their raw materials, harvested by enslaved laborers or native workers, back to their mother country. The mother country sent back finished materials of all sorts: textiles, tools, clothing. The colonists could purchase these goods only from their mother country; trade with other countries was forbidden. The 1500s and early 1600s also introduced the process of commodification to the New World. American silver, tobacco, and other items, which were used by native peoples for ritual purposes, became European commodities with a monetary value that could be bought and sold. Before the arrival of the Spanish, for example, the Inca people of the Andes consumed chicha , a corn beer, for ritual purposes only. When the Spanish discovered chicha, they bought and traded for it, turning it into a commodity instead of a ritual substance. Commodification thus recast native economies and spurred the process of early commercial capitalism. New World resources, from plants to animal pelts, held the promise of wealth for European imperial powers. THE COLUMBIAN EXCHANGE As Europeans traversed the Atlantic, they brought with them plants, animals, and diseases that changed lives and landscapes on both sides of the ocean. These two-way exchanges between the Americas and Europe/Africa are known collectively as the Columbian Exchange ( Figure 2.15 ). Of all the commodities in the Atlantic World, sugar proved to be the most important. Indeed, sugar carried the same economic importance as oil does today. European rivals raced to create sugar plantations in the Americas and fought wars for control of some of the best sugar production areas. Although refined sugar was available in the Old World, Europe’s harsher climate made sugarcane difficult to grow, and it was not plentiful. Columbus brought sugar to Hispaniola in 1493, and the new crop was growing there by the end of the 1490s. By the first decades of the 1500s, the Spanish were building sugar mills on the island. Over the next century of colonization, Caribbean islands and most other tropical areas became centers of sugar production. Though of secondary importance to sugar, tobacco achieved great value for Europeans as a cash crop as well. Native peoples had been growing it for medicinal and ritual purposes for centuries before European contact, smoking it in pipes or powdering it to use as snuff. They believed tobacco could improve concentration and enhance wisdom. To some, its use meant achieving an entranced, altered, or divine state; entering a spiritual place. Tobacco was unknown in Europe before 1492, and it carried a negative stigma at first. The early Spanish explorers considered natives’ use of tobacco to be proof of their savagery and, because of the fire and smoke produced in the consumption of tobacco, evidence of the Devil’s sway in the New World. Gradually, however, European colonists became accustomed to and even took up the habit of smoking, and they brought it across the Atlantic. As did the Native Americans, Europeans ascribed medicinal properties to tobacco, claiming that it could cure headaches and skin irritations. Even so, Europeans did not import tobacco in great quantities until the 1590s. At that time, it became the first truly global commodity; English, French, Dutch, Spanish, and Portuguese colonists all grew it for the world market. Native peoples also introduced Europeans to chocolate, made from cacao seeds and used by the Aztec in Mesoamerica as currency. Mesoamerican Natives consumed unsweetened chocolate in a drink with chili peppers, vanilla, and a spice called achiote. This chocolate drink— xocolatl —was part of ritual ceremonies like marriage and an everyday item for those who could afford it. Chocolate contains theobromine, a stimulant, which may be why native people believed it brought them closer to the sacred world. Spaniards in the New World considered drinking chocolate a vile practice; one called chocolate “the Devil’s vomit.” In time, however, they introduced the beverage to Spain. At first, chocolate was available only in the Spanish court, where the elite mixed it with sugar and other spices. Later, as its availability spread, chocolate gained a reputation as a love potion. The crossing of the Atlantic by plants like cacao and tobacco illustrates the ways in which the discovery of the New World changed the habits and behaviors of Europeans. Europeans changed the New World in turn, not least by bringing Old World animals to the Americas. On his second voyage, Christopher Columbus brought pigs, horses, cows, and chickens to the islands of the Caribbean. Later explorers followed suit, introducing new animals or reintroducing ones that had died out (like horses). With less vulnerability to disease, these animals often fared better than humans in their new home, thriving both in the wild and in domestication. Europeans encountered New World animals as well. Because European Christians understood the world as a place of warfare between God and Satan, many believed the Americas, which lacked Christianity, were home to the Devil and his minions. The exotic, sometimes bizarre, appearances and habits of animals in the Americas that were previously unknown to Europeans, such as manatees, sloths, and poisonous snakes, confirmed this association. Over time, however, they began to rely more on observation of the natural world than solely on scripture. This shift—from seeing the Bible as the source of all received wisdom to trusting observation or empiricism—is one of the major outcomes of the era of early globalization. Travelers between the Americas, Africa, and Europe also included microbes: silent, invisible life forms that had profound and devastating consequences. Native peoples had no immunity to diseases from across the Atlantic, to which they had never been exposed. European explorers unwittingly brought with them chickenpox, measles, mumps, and smallpox , which ravaged native peoples despite their attempts to treat the diseases, decimating some populations and wholly destroying others ( Figure 2.16 ). In eastern North America, some native peoples interpreted death from disease as a hostile act. Some groups, including the Iroquois, engaged in raids or “ mourning wars ,” taking enemy prisoners in order to assuage their grief and replace the departed. In a special ritual, the prisoners were “requickened”—assigned the identity of a dead person—and adopted by the bereaved family to take the place of their dead. As the toll from disease rose, mourning wars intensified and expanded.
biology
Chapter Outline 21.1 Viral Evolution, Morphology, and Classification 21.2 Virus Infections and Hosts 21.3 Prevention and Treatment of Viral Infections 21.4 Other Acellular Entities: Prions and Viroids Introduction No one knows exactly when viruses emerged or from where they came, since viruses do not leave historical footprints such as fossils. Modern viruses are thought to be a mosaic of bits and pieces of nucleic acids picked up from various sources along their respective evolutionary paths. Viruses are acellular, parasitic entities that are not classified within any kingdom. Unlike most living organisms, viruses are not cells and cannot divide. Instead, they infect a host cell and use the host’s replication processes to produce identical progeny virus particles. Viruses infect organisms as diverse as bacteria, plants, and animals. They exist in a netherworld between a living organism and a nonliving entity. Living things grow, metabolize, and reproduce. Viruses replicate, but to do so, they are entirely dependent on their host cells. They do not metabolize or grow, but are assembled in their mature form.
[ { "answer": { "ans_choice": 1, "ans_text": "Viruses are acellular." }, "bloom": null, "hl_context": "Chapter Outline 21.1 Viral Evolution , Morphology , and Classification 21.2 Virus Infections and Hosts 21.3 Prevention and Treatment of Viral Infections 21.4 Other Acellular Entities : Prions and Viroids Introduction No one knows exactly when viruses emerged or from where they came , since viruses do not leave historical footprints such as fossils . Modern viruses are thought to be a mosaic of bits and pieces of nucleic acids picked up from various sources along their respective evolutionary paths . <hl> Viruses are acellular , parasitic entities that are not classified within any kingdom . <hl> Unlike most living organisms , viruses are not cells and cannot divide . Instead , they infect a host cell and use the host ’ s replication processes to produce identical progeny virus particles . Viruses infect organisms as diverse as bacteria , plants , and animals . They exist in a netherworld between a living organism and a nonliving entity . Living things grow , metabolize , and reproduce . Viruses replicate , but to do so , they are entirely dependent on their host cells . They do not metabolize or grow , but are assembled in their mature form .", "hl_sentences": "Viruses are acellular , parasitic entities that are not classified within any kingdom .", "question": { "cloze_format": "The statement that is true is ___.", "normal_format": "Which statement is true?", "question_choices": [ "A virion contains DNA and RNA.", "Viruses are acellular.", "Viruses replicate outside of the cell.", "Most viruses are easily visualized with a light microscope." ], "question_id": "fs-idp108174880", "question_text": "Which statement is true?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 3, "ans_text": "both b and c" }, "bloom": null, "hl_context": "<hl> A virus attaches to a specific receptor site on the host cell membrane through attachment proteins in the capsid or via glycoproteins embedded in the viral envelope . <hl> The specificity of this interaction determines the host — and the cells within the host — that can be infected by a particular virus . This can be illustrated by thinking of several keys and several locks , where each key will fit only one specific lock . <hl> Enveloped virions like HIV , the causative agent in AIDS , consist of nucleic acid ( RNA in the case of HIV ) and capsid proteins surrounded by a phospholipid bilayer envelope and its associated proteins . <hl> <hl> Glycoproteins embedded in the viral envelope are used to attach to host cells . <hl> Other envelope proteins are the matrix proteins that stabilize the envelope and often play a role in the assembly of progeny virions . Chicken pox , influenza , and mumps are examples of diseases caused by viruses with envelopes . Because of the fragility of the envelope , non-enveloped viruses are more resistant to changes in temperature , pH , and some disinfectants than enveloped viruses .", "hl_sentences": "A virus attaches to a specific receptor site on the host cell membrane through attachment proteins in the capsid or via glycoproteins embedded in the viral envelope . Enveloped virions like HIV , the causative agent in AIDS , consist of nucleic acid ( RNA in the case of HIV ) and capsid proteins surrounded by a phospholipid bilayer envelope and its associated proteins . Glycoproteins embedded in the viral envelope are used to attach to host cells .", "question": { "cloze_format": "The viral ________ plays a role in attaching a virion to the host cell.", "normal_format": "Which viral plays a role in attaching a virion to the cell host?", "question_choices": [ "core", "capsid", "envelope", "both b and c" ], "question_id": "fs-idp56983888", "question_text": "The viral ________ plays a role in attaching a virion to the host cell." }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 3, "ans_text": "vary in shape" }, "bloom": null, "hl_context": "<hl> Viruses come in many shapes and sizes , but these are consistent and distinct for each viral family . <hl> All virions have a nucleic acid genome covered by a protective layer of proteins , called a capsid . The capsid is made up of protein subunits called capsomeres . Some viral capsids are simple polyhedral “ spheres , ” whereas others are quite complex in structure . In general , the shapes of viruses are classified into four groups : filamentous , isometric ( or icosahedral ) , enveloped , and head and tail . Filamentous viruses are long and cylindrical . Many plant viruses are filamentous , including TMV . Isometric viruses have shapes that are roughly spherical , such as poliovirus or herpesviruses . Enveloped viruses have membranes surrounding capsids . Animal viruses , such as HIV , are frequently enveloped . Head and tail viruses infect bacteria and have a head that is similar to icosahedral viruses and a tail shape like filamentous viruses . <hl> Viruses are diverse entities . <hl> <hl> They vary in their structure , their replication methods , and in their target hosts . <hl> Nearly all forms of life — from bacteria and archaea to eukaryotes such as plants , animals , and fungi — have viruses that infect them . While most biological diversity can be understood through evolutionary history , such as how species have adapted to conditions and environments , much about virus origins and evolution remains unknown .", "hl_sentences": "Viruses come in many shapes and sizes , but these are consistent and distinct for each viral family . Viruses are diverse entities . They vary in their structure , their replication methods , and in their target hosts .", "question": { "cloze_format": "Viruses_______.", "normal_format": "What is a characteristic of Viruses? ", "question_choices": [ "all have a round shape", "cannot have a long shape", "do not maintain any shape", "vary in shape" ], "question_id": "fs-idm54168336", "question_text": "Viruses_______." }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 3, "ans_text": "Newly released virions can infect adjacent cells." }, "bloom": null, "hl_context": "Bacteriophages are viruses that infect bacteria ( Figure 21.9 ) . When infection of a cell by a bacteriophage results in the production of new virions , the infection is said to be productive . If the virions are released by bursting the cell , the virus replicates by means of a lytic cycle ( Figure 21.10 ) . An example of a lytic bacteriophage is T4 , which infects Escherichia coli found in the human intestinal tract . Sometimes , however , a virus can remain within the cell without being released . <hl> For example , when a temperate bacteriophage infects a bacterial cell , it replicates by means of a lysogenic cycle ( Figure 21.10 ) , and the viral genome is incorporated into the genome of the host cell . <hl> When the phage DNA is incorporated into the host cell genome , it is called a prophage . An example of a lysogenic bacteriophage is the λ ( lambda ) virus , which also infects the E . coli bacterium . Viruses that infect plant or animal cells may also undergo infections where they are not producing virions for long periods . An example is the animal herpesviruses , including herpes simplex viruses , the cause of oral and genital herpes in humans . <hl> In a process called latency , these viruses can exist in nervous tissue for long periods of time without producing new virions , only to leave latency periodically and cause lesions in the skin where the virus replicates . <hl> <hl> Even though there are similarities between lysogeny and latency , the term lysogenic cycle is usually reserved to describe bacteriophages . <hl> Latency will be described in more detail below . A virus must use cell processes to replicate . <hl> The viral replication cycle can produce dramatic biochemical and structural changes in the host cell , which may cause cell damage . <hl> These changes , called cytopathic ( causing cell damage ) effects , can change cell functions or even destroy the cell . Some infected cells , such as those infected by the common cold virus known as rhinovirus , die through lysis ( bursting ) or apoptosis ( programmed cell death or “ cell suicide ” ) , releasing all progeny virions at once . The symptoms of viral diseases result from the immune response to the virus , which attempts to control and eliminate the virus from the body , and from cell damage caused by the virus . Many animal viruses , such as HIV ( human immunodeficiency virus ) , leave the infected cells of the immune system by a process known as budding , where virions leave the cell individually . During the budding process , the cell does not undergo lysis and is not immediately killed . However , the damage to the cells that the virus infects may make it impossible for the cells to function normally , even though the cells remain alive for a period of time . <hl> Most productive viral infections follow similar steps in the virus replication cycle : attachment , penetration , uncoating , replication , assembly , and release ( Figure 21.8 ) . <hl>", "hl_sentences": "For example , when a temperate bacteriophage infects a bacterial cell , it replicates by means of a lysogenic cycle ( Figure 21.10 ) , and the viral genome is incorporated into the genome of the host cell . In a process called latency , these viruses can exist in nervous tissue for long periods of time without producing new virions , only to leave latency periodically and cause lesions in the skin where the virus replicates . Even though there are similarities between lysogeny and latency , the term lysogenic cycle is usually reserved to describe bacteriophages . The viral replication cycle can produce dramatic biochemical and structural changes in the host cell , which may cause cell damage . Most productive viral infections follow similar steps in the virus replication cycle : attachment , penetration , uncoating , replication , assembly , and release ( Figure 21.8 ) .", "question": { "cloze_format": "Of viral replication, it is a false statement that ___ .", "normal_format": "Which statement is not true of viral replication?", "question_choices": [ "A lysogenic cycle kills the host cell.", "There are six basic steps in the viral replication cycle.", "Viral replication does not affect host cell function.", "Newly released virions can infect adjacent cells." ], "question_id": "fs-idm138486528", "question_text": "Which statement is not true of viral replication?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 1, "ans_text": "During attachment, the virus attaches at specific sites on the cell surface." }, "bloom": null, "hl_context": "<hl> A virus attaches to a specific receptor site on the host cell membrane through attachment proteins in the capsid or via glycoproteins embedded in the viral envelope . <hl> The specificity of this interaction determines the host — and the cells within the host — that can be infected by a particular virus . This can be illustrated by thinking of several keys and several locks , where each key will fit only one specific lock . Viruses can be seen as obligate , intracellular parasites . A virus must attach to a living cell , be taken inside , manufacture its proteins and copy its genome , and find a way to escape the cell so that the virus can infect other cells . Viruses can infect only certain species of hosts and only certain cells within that host . Cells that a virus may use to replicate are called permissive . <hl> For most viruses , the molecular basis for this specificity is that a particular surface molecule known as the viral receptor must be found on the host cell surface for the virus to attach . <hl> Also , metabolic and host cell immune response differences seen in different cell types based on differential gene expression are a likely factor in which cells a virus may target for replication . The permissive cell must make the substances that the virus needs or the virus will not be able to replicate there .", "hl_sentences": "A virus attaches to a specific receptor site on the host cell membrane through attachment proteins in the capsid or via glycoproteins embedded in the viral envelope . For most viruses , the molecular basis for this specificity is that a particular surface molecule known as the viral receptor must be found on the host cell surface for the virus to attach .", "question": { "cloze_format": "The statement that is true of viral replication is that ___.", "normal_format": "Which statement is true of viral replication?", "question_choices": [ "In the process of apoptosis, the cell survives.", "During attachment, the virus attaches at specific sites on the cell surface.", "The viral capsid helps the host cell produce more copies of the viral genome.", "mRNA works outside of the host cell to produce enzymes and proteins." ], "question_id": "fs-idp96144208", "question_text": "Which statement is true of viral replication?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 2, "ans_text": "It transcribes RNA to make DNA." }, "bloom": null, "hl_context": "The replication mechanism depends on the viral genome . DNA viruses usually use host cell proteins and enzymes to make additional DNA that is transcribed to messenger RNA ( mRNA ) , which is then used to direct protein synthesis . RNA viruses usually use the RNA core as a template for synthesis of viral genomic RNA and mRNA . The viral mRNA directs the host cell to synthesize viral enzymes and capsid proteins , and assemble new virions . Of course , there are exceptions to this pattern . If a host cell does not provide the enzymes necessary for viral replication , viral genes supply the information to direct synthesis of the missing proteins . Retroviruses , such as HIV , have an RNA genome that must be reverse transcribed into DNA , which then is incorporated into the host cell genome . They are within group VI of the Baltimore classification scheme . <hl> To convert RNA into DNA , retroviruses must contain genes that encode the virus-specific enzyme reverse transcriptase that transcribes an RNA template to DNA . <hl> Reverse transcription never occurs in uninfected host cells — the needed enzyme reverse transcriptase is only derived from the expression of viral genes within the infected host cells . The fact that HIV produces some of its own enzymes not found in the host has allowed researchers to develop drugs that inhibit these enzymes . These drugs , including the reverse transcriptase inhibitor AZT , inhibit HIV replication by reducing the activity of the enzyme without affecting the host ’ s metabolism . This approach has led to the development of a variety of drugs used to treat HIV and has been effective at reducing the number of infectious virions ( copies of viral RNA ) in the blood to non-detectable levels in many HIV-infected individuals . <hl> Reverse transcriptase makes DNA from the RNA genome ; DNA is then incorporated in the host genome ; mRNA is transcribed from the incorporated DNA <hl>", "hl_sentences": "To convert RNA into DNA , retroviruses must contain genes that encode the virus-specific enzyme reverse transcriptase that transcribes an RNA template to DNA . Reverse transcriptase makes DNA from the RNA genome ; DNA is then incorporated in the host genome ; mRNA is transcribed from the incorporated DNA", "question": { "cloze_format": "Of reverse transcriptase, it can be said that ___ .", "normal_format": "Which statement is true of reverse transcriptase?", "question_choices": [ "It is a nucleic acid.", "It infects cells.", "It transcribes RNA to make DNA.", "It is a lipid." ], "question_id": "fs-idm150416560", "question_text": "Which statement is true of reverse transcriptase?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 3, "ans_text": "either RNA or DNA" }, "bloom": null, "hl_context": "Some animal-infecting viruses , including the hepatitis C virus discussed above , are known as oncogenic viruses : They have the ability to cause cancer . These viruses interfere with the normal regulation of the host cell cycle either by either introducing genes that stimulate unregulated cell growth ( oncogenes ) or by interfering with the expression of genes that inhibit cell growth . <hl> Oncogenic viruses can be either DNA or RNA viruses . <hl> Cancers known to be associated with viral infections include cervical cancer caused by human papillomavirus ( HPV ) ( Figure 21.12 ) , liver cancer caused by hepatitis B virus , T-cell leukemia , and several types of lymphoma .", "hl_sentences": "Oncogenic viruses can be either DNA or RNA viruses .", "question": { "cloze_format": "Oncogenic virus cores can be_______.", "normal_format": "Which can oncogenic virus cores be?", "question_choices": [ "RNA", "DNA", "neither RNA nor DNA", "either RNA or DNA" ], "question_id": "fs-idm107061648", "question_text": "Oncogenic virus cores can be_______." }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 0, "ans_text": "They use the host cell’s machinery to produce new copies of their genome." }, "bloom": null, "hl_context": "<hl> The replication mechanism depends on the viral genome . <hl> <hl> DNA viruses usually use host cell proteins and enzymes to make additional DNA that is transcribed to messenger RNA ( mRNA ) , which is then used to direct protein synthesis . <hl> RNA viruses usually use the RNA core as a template for synthesis of viral genomic RNA and mRNA . The viral mRNA directs the host cell to synthesize viral enzymes and capsid proteins , and assemble new virions . Of course , there are exceptions to this pattern . If a host cell does not provide the enzymes necessary for viral replication , viral genes supply the information to direct synthesis of the missing proteins . Retroviruses , such as HIV , have an RNA genome that must be reverse transcribed into DNA , which then is incorporated into the host cell genome . They are within group VI of the Baltimore classification scheme . To convert RNA into DNA , retroviruses must contain genes that encode the virus-specific enzyme reverse transcriptase that transcribes an RNA template to DNA . Reverse transcription never occurs in uninfected host cells — the needed enzyme reverse transcriptase is only derived from the expression of viral genes within the infected host cells . The fact that HIV produces some of its own enzymes not found in the host has allowed researchers to develop drugs that inhibit these enzymes . These drugs , including the reverse transcriptase inhibitor AZT , inhibit HIV replication by reducing the activity of the enzyme without affecting the host ’ s metabolism . This approach has led to the development of a variety of drugs used to treat HIV and has been effective at reducing the number of infectious virions ( copies of viral RNA ) in the blood to non-detectable levels in many HIV-infected individuals . <hl> In DNA viruses , the viral DNA directs the host cell ’ s replication proteins to synthesize new copies of the viral genome and to transcribe and translate that genome into viral proteins . <hl> DNA viruses cause human diseases , such as chickenpox , hepatitis B , and some venereal diseases , like herpes and genital warts .", "hl_sentences": "The replication mechanism depends on the viral genome . DNA viruses usually use host cell proteins and enzymes to make additional DNA that is transcribed to messenger RNA ( mRNA ) , which is then used to direct protein synthesis . In DNA viruses , the viral DNA directs the host cell ’ s replication proteins to synthesize new copies of the viral genome and to transcribe and translate that genome into viral proteins .", "question": { "cloze_format": "A true statement of DNA viruses is that ___ .", "normal_format": "Which is true of DNA viruses?", "question_choices": [ "They use the host cell’s machinery to produce new copies of their genome.", "They all have envelopes.", "They are the only kind of viruses that can cause cancer.", "They are not important plant pathogens." ], "question_id": "fs-idm23212144", "question_text": "Which is true of DNA viruses?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 3, "ans_text": "bacteria" }, "bloom": null, "hl_context": "<hl> Bacteriophages are viruses that infect bacteria ( Figure 21.9 ) . <hl> When infection of a cell by a bacteriophage results in the production of new virions , the infection is said to be productive . If the virions are released by bursting the cell , the virus replicates by means of a lytic cycle ( Figure 21.10 ) . An example of a lytic bacteriophage is T4 , which infects Escherichia coli found in the human intestinal tract . Sometimes , however , a virus can remain within the cell without being released . For example , when a temperate bacteriophage infects a bacterial cell , it replicates by means of a lysogenic cycle ( Figure 21.10 ) , and the viral genome is incorporated into the genome of the host cell . When the phage DNA is incorporated into the host cell genome , it is called a prophage . An example of a lysogenic bacteriophage is the λ ( lambda ) virus , which also infects the E . coli bacterium . Viruses that infect plant or animal cells may also undergo infections where they are not producing virions for long periods . An example is the animal herpesviruses , including herpes simplex viruses , the cause of oral and genital herpes in humans . In a process called latency , these viruses can exist in nervous tissue for long periods of time without producing new virions , only to leave latency periodically and cause lesions in the skin where the virus replicates . Even though there are similarities between lysogeny and latency , the term lysogenic cycle is usually reserved to describe bacteriophages . Latency will be described in more detail below .", "hl_sentences": "Bacteriophages are viruses that infect bacteria ( Figure 21.9 ) .", "question": { "cloze_format": "A bacteriophage can infect ________.", "normal_format": "What can a bacteriophage infect?", "question_choices": [ "the lungs", "viruses", "prions", "bacteria" ], "question_id": "fs-idm193317248", "question_text": "A bacteriophage can infect ________." }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 2, "ans_text": "antibiotics" }, "bloom": null, "hl_context": "<hl> A third use of viruses in medicine relies on their specificity and involves using bacteriophages in the treatment of bacterial infections . <hl> Bacterial diseases have been treated with antibiotics since the 1940s . <hl> However , over time , many bacteria have developed resistance to antibiotics . <hl> A good example is methicillin-resistant Staphylococcus aureus ( MRSA , pronounced “ mersa ” ) , an infection commonly acquired in hospitals . This bacterium is resistant to a variety of antibiotics , making it difficult to treat . <hl> The use of bacteriophages specific for such bacteria would bypass their resistance to antibiotics and specifically kill them . <hl> <hl> Although phage therapy is in use in the Republic of Georgia to treat antibiotic-resistant bacteria , its use to treat human diseases has not been approved in most countries . <hl> However , the safety of the treatment was confirmed in the United States when the U . S . Food and Drug Administration approved spraying meats with bacteriophages to destroy the food pathogen Listeria . <hl> As more and more antibiotic-resistant strains of bacteria evolve , the use of bacteriophages might be a potential solution to the problem , and the development of phage therapy is of much interest to researchers worldwide . <hl> 21.4 Other Acellular Entities : Prions and Viroids Learning Objectives By the end of this section , you will be able to : <hl> Another way of treating viral infections is the use of antiviral drugs . <hl> These drugs often have limited success in curing viral disease , but in many cases , they have been used to control and reduce symptoms for a wide variety of viral diseases . For most viruses , these drugs can inhibit the virus by blocking the actions of one or more of its proteins . It is important that the targeted proteins be encoded by viral genes and that these molecules are not present in a healthy host cell . In this way , viral growth is inhibited without damaging the host . There are large numbers of antiviral drugs available to treat infections , some specific for a particular virus and others that can affect multiple viruses . <hl> While we do have limited numbers of effective antiviral drugs , such as those used to treat HIV and influenza , the primary method of controlling viral disease is by vaccination , which is intended to prevent outbreaks by building immunity to a virus or virus family ( Figure 21.14 ) . <hl> <hl> Vaccines may be prepared using live viruses , killed viruses , or molecular subunits of the virus . <hl> <hl> The killed viral vaccines and subunit viruses are both incapable of causing disease . <hl>", "hl_sentences": "A third use of viruses in medicine relies on their specificity and involves using bacteriophages in the treatment of bacterial infections . However , over time , many bacteria have developed resistance to antibiotics . The use of bacteriophages specific for such bacteria would bypass their resistance to antibiotics and specifically kill them . Although phage therapy is in use in the Republic of Georgia to treat antibiotic-resistant bacteria , its use to treat human diseases has not been approved in most countries . As more and more antibiotic-resistant strains of bacteria evolve , the use of bacteriophages might be a potential solution to the problem , and the development of phage therapy is of much interest to researchers worldwide . Another way of treating viral infections is the use of antiviral drugs . While we do have limited numbers of effective antiviral drugs , such as those used to treat HIV and influenza , the primary method of controlling viral disease is by vaccination , which is intended to prevent outbreaks by building immunity to a virus or virus family ( Figure 21.14 ) . Vaccines may be prepared using live viruses , killed viruses , or molecular subunits of the virus . The killed viral vaccines and subunit viruses are both incapable of causing disease .", "question": { "cloze_format": "___ is NOT used to treat active viral disease.", "normal_format": "Which of the following is NOT used to treat active viral disease?", "question_choices": [ "vaccines", "antiviral drugs", "antibiotics", "phage therapy" ], "question_id": "fs-idp41822000", "question_text": "Which of the following is NOT used to treat active viral disease?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 3, "ans_text": "stimulate an immune response" }, "bloom": null, "hl_context": "In hepatitis C infections , the virus grows and reproduces in liver cells , causing low levels of liver damage . The damage is so low that infected individuals are often unaware that they are infected , and many infections are detected only by routine blood work on patients with risk factors such as intravenous drug use . <hl> On the other hand , since many of the symptoms of viral diseases are caused by immune responses , a lack of symptoms is an indication of a weak immune response to the virus . <hl> This allows for the virus to escape elimination by the immune system and persist in individuals for years , all the while producing low levels of progeny virions in what is known as a chronic viral disease . Chronic infection of the liver by this virus leads to a much greater chance of developing liver cancer , sometimes as much as 30 years after the initial infection .", "hl_sentences": "On the other hand , since many of the symptoms of viral diseases are caused by immune responses , a lack of symptoms is an indication of a weak immune response to the virus .", "question": { "cloze_format": "Vaccines_______.", "normal_format": "Which of the following is correct about vaccines?", "question_choices": [ "are similar to viroids", "are only needed once", "kill viruses", "stimulate an immune response" ], "question_id": "fs-idm100043872", "question_text": "Vaccines_______." }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 2, "ans_text": "DNA" }, "bloom": null, "hl_context": "<hl> Fatal neurodegenerative diseases , such as kuru in humans and bovine spongiform encephalopathy ( BSE ) in cattle ( commonly known as “ mad cow disease ” ) were shown to be transmitted by prions . <hl> The disease was spread by the consumption of meat , nervous tissue , or internal organs between members of the same species . Kuru , native to humans in Papua New Guinea , was spread from human to human via ritualistic cannibalism . BSE , originally detected in the United Kingdom , was spread between cattle by the practice of including cattle nervous tissue in feed for other cattle . Individuals with kuru and BSE show symptoms of loss of motor control and unusual behaviors , such as uncontrolled bursts of laughter with kuru , followed by death . Kuru was controlled by inducing the population to abandon its ritualistic cannibalism . <hl> Prions , so-called because they are proteinaceous , are infectious particles — smaller than viruses — that contain no nucleic acids ( neither DNA nor RNA ) . <hl> Historically , the idea of an infectious agent that did not use nucleic acids was considered impossible , but pioneering work by Nobel Prize-winning biologist Stanley Prusiner has convinced the majority of biologists that such agents do indeed exist .", "hl_sentences": "Fatal neurodegenerative diseases , such as kuru in humans and bovine spongiform encephalopathy ( BSE ) in cattle ( commonly known as “ mad cow disease ” ) were shown to be transmitted by prions . Prions , so-called because they are proteinaceous , are infectious particles — smaller than viruses — that contain no nucleic acids ( neither DNA nor RNA ) .", "question": { "cloze_format": "___ is not associated with prions.", "normal_format": "Which of the following is not associated with prions?", "question_choices": [ "replicating shapes", "mad cow disease", "DNA", "toxic proteins" ], "question_id": "fs-idp63929504", "question_text": "Which of the following is not associated with prions?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 0, "ans_text": "They are single-stranded RNA particles." }, "bloom": null, "hl_context": "<hl> Viroids Viroids are plant pathogens : small , single-stranded , circular RNA particles that are much simpler than a virus . <hl> They do not have a capsid or outer envelope , but like viruses can reproduce only within a host cell . Viroids do not , however , manufacture any proteins , and they only produce a single , specific RNA molecule . Human diseases caused by viroids have yet to be identified .", "hl_sentences": "Viroids Viroids are plant pathogens : small , single-stranded , circular RNA particles that are much simpler than a virus .", "question": { "cloze_format": "Of viroids, it is a true statement that ___ .", "normal_format": "Which statement is true of viroids?", "question_choices": [ "They are single-stranded RNA particles.", "They reproduce only outside of the cell.", "They produce proteins.", "They affect both plants and animals." ], "question_id": "fs-idm41041152", "question_text": "Which statement is true of viroids?" }, "references_are_paraphrase": null } ]
21
21.1 Viral Evolution, Morphology, and Classification Learning Objectives By the end of this section, you will be able to: Describe how viruses were first discovered and how they are detected Discuss three hypotheses about how viruses evolved Recognize the basic shapes of viruses Understand past and emerging classification systems for viruses Viruses are diverse entities. They vary in their structure, their replication methods, and in their target hosts. Nearly all forms of life—from bacteria and archaea to eukaryotes such as plants, animals, and fungi—have viruses that infect them. While most biological diversity can be understood through evolutionary history, such as how species have adapted to conditions and environments, much about virus origins and evolution remains unknown. Discovery and Detection Viruses were first discovered after the development of a porcelain filter, called the Chamberland-Pasteur filter, which could remove all bacteria visible in the microscope from any liquid sample. In 1886, Adolph Meyer demonstrated that a disease of tobacco plants, tobacco mosaic disease, could be transferred from a diseased plant to a healthy one via liquid plant extracts. In 1892, Dmitri Ivanowski showed that this disease could be transmitted in this way even after the Chamberland-Pasteur filter had removed all viable bacteria from the extract. Still, it was many years before it was proven that these “filterable” infectious agents were not simply very small bacteria but were a new type of very small, disease-causing particle. Virions , single virus particles, are very small, about 20–250 nanometers in diameter. These individual virus particles are the infectious form of a virus outside the host cell. Unlike bacteria (which are about 100-times larger), we cannot see viruses with a light microscope, with the exception of some large virions of the poxvirus family. It was not until the development of the electron microscope in the late 1930s that scientists got their first good view of the structure of the tobacco mosaic virus (TMV) ( Figure 21.1 ) and other viruses ( Figure 21.2 ). The surface structure of virions can be observed by both scanning and transmission electron microscopy, whereas the internal structures of the virus can only be observed in images from a transmission electron microscope. The use of these technologies has allowed for the discovery of many viruses of all types of living organisms. They were initially grouped by shared morphology. Later, groups of viruses were classified by the type of nucleic acid they contained, DNA or RNA, and whether their nucleic acid was single- or double-stranded. More recently, molecular analysis of viral replicative cycles has further refined their classification. Evolution of Viruses Although biologists have accumulated a significant amount of knowledge about how present-day viruses evolve, much less is known about how viruses originated in the first place. When exploring the evolutionary history of most organisms, scientists can look at fossil records and similar historic evidence. However, viruses do not fossilize, so researchers must conjecture by investigating how today’s viruses evolve and by using biochemical and genetic information to create speculative virus histories. While most findings agree that viruses don’t have a single common ancestor, scholars have yet to find a single hypothesis about virus origins that is fully accepted in the field. One such hypothesis, called devolution or the regressive hypothesis, proposes to explain the origin of viruses by suggesting that viruses evolved from free-living cells. However, many components of how this process might have occurred are a mystery. A second hypothesis (called escapist or the progressive hypothesis) accounts for viruses having either an RNA or a DNA genome and suggests that viruses originated from RNA and DNA molecules that escaped from a host cell. A third hypothesis posits a system of self-replication similar to that of other self-replicating molecules, likely evolving alongside the cells they rely on as hosts; studies of some plant pathogens support this hypothesis. As technology advances, scientists may develop and refine further hypotheses to explain the origin of viruses. The emerging field called virus molecular systematics attempts to do just that through comparisons of sequenced genetic material. These researchers hope to one day better understand the origin of viruses, a discovery that could lead to advances in the treatments for the ailments they produce. Viral Morphology Viruses are acellular , meaning they are biological entities that do not have a cellular structure. They therefore lack most of the components of cells, such as organelles, ribosomes, and the plasma membrane. A virion consists of a nucleic acid core, an outer protein coating or capsid, and sometimes an outer envelope made of protein and phospholipid membranes derived from the host cell. Viruses may also contain additional proteins, such as enzymes. The most obvious difference between members of viral families is their morphology, which is quite diverse. An interesting feature of viral complexity is that the complexity of the host does not correlate with the complexity of the virion. Some of the most complex virion structures are observed in bacteriophages, viruses that infect the simplest living organisms, bacteria. Morphology Viruses come in many shapes and sizes, but these are consistent and distinct for each viral family. All virions have a nucleic acid genome covered by a protective layer of proteins, called a capsid . The capsid is made up of protein subunits called capsomeres . Some viral capsids are simple polyhedral “spheres,” whereas others are quite complex in structure. In general, the shapes of viruses are classified into four groups: filamentous, isometric (or icosahedral), enveloped, and head and tail. Filamentous viruses are long and cylindrical. Many plant viruses are filamentous, including TMV. Isometric viruses have shapes that are roughly spherical, such as poliovirus or herpesviruses. Enveloped viruses have membranes surrounding capsids. Animal viruses, such as HIV, are frequently enveloped. Head and tail viruses infect bacteria and have a head that is similar to icosahedral viruses and a tail shape like filamentous viruses. Many viruses use some sort of glycoprotein to attach to their host cells via molecules on the cell called viral receptors ( Figure 21.3 ). For these viruses, attachment is a requirement for later penetration of the cell membrane, so they can complete their replication inside the cell. The receptors that viruses use are molecules that are normally found on cell surfaces and have their own physiological functions. Viruses have simply evolved to make use of these molecules for their own replication. For example, HIV uses the CD4 molecule on T lymphocytes as one of its receptors. CD4 is a type of molecule called a cell adhesion molecule, which functions to keep different types of immune cells in close proximity to each other during the generation of a T lymphocyte immune response. Among the most complex virions known, the T4 bacteriophage, which infects the Escherichia coli bacterium, has a tail structure that the virus uses to attach to host cells and a head structure that houses its DNA. Adenovirus, a non-enveloped animal virus that causes respiratory illnesses in humans, uses glycoprotein spikes protruding from its capsomeres to attach to host cells. Non-enveloped viruses also include those that cause polio (poliovirus), plantar warts (papillomavirus), and hepatitis A (hepatitis A virus). Enveloped virions like HIV, the causative agent in AIDS, consist of nucleic acid (RNA in the case of HIV) and capsid proteins surrounded by a phospholipid bilayer envelope and its associated proteins. Glycoproteins embedded in the viral envelope are used to attach to host cells. Other envelope proteins are the matrix proteins that stabilize the envelope and often play a role in the assembly of progeny virions. Chicken pox, influenza, and mumps are examples of diseases caused by viruses with envelopes. Because of the fragility of the envelope, non-enveloped viruses are more resistant to changes in temperature, pH, and some disinfectants than enveloped viruses. Overall, the shape of the virion and the presence or absence of an envelope tell us little about what disease the virus may cause or what species it might infect, but they are still useful means to begin viral classification ( Figure 21.4 ). Visual Connection Which of the following statements about virus structure is true? All viruses are encased in a viral membrane. The capsomere is made up of small protein subunits called capsids. DNA is the genetic material in all viruses. Glycoproteins help the virus attach to the host cell. Types of Nucleic Acid Unlike nearly all living organisms that use DNA as their genetic material, viruses may use either DNA or RNA as theirs. The virus core contains the genome or total genetic content of the virus. Viral genomes tend to be small, containing only those genes that encode proteins that the virus cannot get from the host cell. This genetic material may be single- or double-stranded. It may also be linear or circular. While most viruses contain a single nucleic acid, others have genomes that have several, which are called segments. In DNA viruses, the viral DNA directs the host cell’s replication proteins to synthesize new copies of the viral genome and to transcribe and translate that genome into viral proteins. DNA viruses cause human diseases, such as chickenpox, hepatitis B, and some venereal diseases, like herpes and genital warts. RNA viruses contain only RNA as their genetic material. To replicate their genomes in the host cell, the RNA viruses encode enzymes that can replicate RNA into DNA, which cannot be done by the host cell. These RNA polymerase enzymes are more likely to make copying errors than DNA polymerases, and therefore often make mistakes during transcription. For this reason, mutations in RNA viruses occur more frequently than in DNA viruses. This causes them to change and adapt more rapidly to their host. Human diseases caused by RNA viruses include hepatitis C, measles, and rabies. Virus Classification To understand the features shared among different groups of viruses, a classification scheme is necessary. As most viruses are not thought to have evolved from a common ancestor, however, the methods that scientists use to classify living things are not very useful. Biologists have used several classification systems in the past, based on the morphology and genetics of the different viruses. However, these earlier classification methods grouped viruses differently, based on which features of the virus they were using to classify them. The most commonly used classification method today is called the Baltimore classification scheme and is based on how messenger RNA (mRNA) is generated in each particular type of virus. Past Systems of Classification Viruses are classified in several ways: by factors such as their core content ( Table 21.1 and Figure 21.3 ), the structure of their capsids, and whether they have an outer envelope. The type of genetic material (DNA or RNA) and its structure (single- or double-stranded, linear or circular, and segmented or non-segmented) are used to classify the virus core structures. Virus Classification by Genome Structure and Core Core Classifications Examples RNA DNA Rabies virus, retroviruses Herpesviruses, smallpox virus Single-stranded Double-stranded Rabies virus, retroviruses Herpesviruses, smallpox virus Linear Circular Rabies virus, retroviruses, herpesviruses, smallpox virus Papillomaviruses, many bacteriophages Non-segmented: genome consists of a single segment of genetic material Segmented: genome is divided into multiple segments Parainfluenza viruses Influenza viruses Table 21.1 Viruses can also be classified by the design of their capsids ( Figure 21.4 and Figure 21.5 ). Capsids are classified as naked icosahedral, enveloped icosahedral, enveloped helical, naked helical, and complex ( Figure 21.6 and Figure 21.7 ). The type of genetic material (DNA or RNA) and its structure (single- or double-stranded, linear or circular, and segmented or non-segmented) are used to classify the virus core structures ( Table 21.2 ). Virus Classification by Capsid Structure Capsid Classification Examples Naked icosahedral Hepatitis A virus, polioviruses Enveloped icosahedral Epstein-Barr virus, herpes simplex virus, rubella virus, yellow fever virus, HIV-1 Enveloped helical Influenza viruses, mumps virus, measles virus, rabies virus Naked helical Tobacco mosaic virus Complex with many proteins; some have combinations of icosahedral and helical capsid structures Herpesviruses, smallpox virus, hepatitis B virus, T4 bacteriophage Table 21.2 Baltimore Classification The most commonly used system of virus classification was developed by Nobel Prize-winning biologist David Baltimore in the early 1970s. In addition to the differences in morphology and genetics mentioned above, the Baltimore classification scheme groups viruses according to how the mRNA is produced during the replicative cycle of the virus. Group I viruses contain double-stranded DNA (dsDNA) as their genome. Their mRNA is produced by transcription in much the same way as with cellular DNA. Group II viruses have single-stranded DNA (ssDNA) as their genome. They convert their single-stranded genomes into a dsDNA intermediate before transcription to mRNA can occur. Group III viruses use dsRNA as their genome. The strands separate, and one of them is used as a template for the generation of mRNA using the RNA-dependent RNA polymerase encoded by the virus. Group IV viruses have ssRNA as their genome with a positive polarity. Positive polarity means that the genomic RNA can serve directly as mRNA. Intermediates of dsRNA, called replicative intermediates , are made in the process of copying the genomic RNA. Multiple, full-length RNA strands of negative polarity (complimentary to the positive-stranded genomic RNA) are formed from these intermediates, which may then serve as templates for the production of RNA with positive polarity, including both full-length genomic RNA and shorter viral mRNAs. Group V viruses contain ssRNA genomes with a negative polarity , meaning that their sequence is complementary to the mRNA. As with Group IV viruses, dsRNA intermediates are used to make copies of the genome and produce mRNA. In this case, the negative-stranded genome can be converted directly to mRNA. Additionally, full-length positive RNA strands are made to serve as templates for the production of the negative-stranded genome. Group VI viruses have diploid (two copies) ssRNA genomes that must be converted, using the enzyme reverse transcriptase , to dsDNA; the dsDNA is then transported to the nucleus of the host cell and inserted into the host genome. Then, mRNA can be produced by transcription of the viral DNA that was integrated into the host genome. Group VII viruses have partial dsDNA genomes and make ssRNA intermediates that act as mRNA, but are also converted back into dsDNA genomes by reverse transcriptase, necessary for genome replication. The characteristics of each group in the Baltimore classification are summarized in Table 21.3 with examples of each group. Baltimore Classification Group Characteristics Mode of mRNA Production Example I Double-stranded DNA mRNA is transcribed directly from the DNA template Herpes simplex (herpesvirus) II Single-stranded DNA DNA is converted to double-stranded form before RNA is transcribed Canine parvovirus (parvovirus) III Double-stranded RNA mRNA is transcribed from the RNA genome Childhood gastroenteritis (rotavirus) IV Single stranded RNA (+) Genome functions as mRNA Common cold (pircornavirus) V Single stranded RNA (-) mRNA is transcribed from the RNA genome Rabies (rhabdovirus) VI Single stranded RNA viruses with reverse transcriptase Reverse transcriptase makes DNA from the RNA genome; DNA is then incorporated in the host genome; mRNA is transcribed from the incorporated DNA Human immunodeficiency virus (HIV) VII Double stranded DNA viruses with reverse transcriptase The viral genome is double-stranded DNA, but viral DNA is replicated through an RNA intermediate; the RNA may serve directly as mRNA or as a template to make mRNA Hepatitis B virus (hepadnavirus) Table 21.3 21.2 Virus Infections and Hosts Learning Objectives By the end of this section, you will be able to: List the steps of replication and explain what occurs at each step Describe the lytic and lysogenic cycles of virus replication Explain the transmission and diseases of animal and plant viruses Discuss the economic impact of animal and plant viruses Viruses can be seen as obligate, intracellular parasites. A virus must attach to a living cell, be taken inside, manufacture its proteins and copy its genome, and find a way to escape the cell so that the virus can infect other cells. Viruses can infect only certain species of hosts and only certain cells within that host. Cells that a virus may use to replicate are called permissive . For most viruses, the molecular basis for this specificity is that a particular surface molecule known as the viral receptor must be found on the host cell surface for the virus to attach. Also, metabolic and host cell immune response differences seen in different cell types based on differential gene expression are a likely factor in which cells a virus may target for replication. The permissive cell must make the substances that the virus needs or the virus will not be able to replicate there. Steps of Virus Infections A virus must use cell processes to replicate. The viral replication cycle can produce dramatic biochemical and structural changes in the host cell, which may cause cell damage. These changes, called cytopathic (causing cell damage) effects, can change cell functions or even destroy the cell. Some infected cells, such as those infected by the common cold virus known as rhinovirus, die through lysis (bursting) or apoptosis (programmed cell death or “cell suicide”), releasing all progeny virions at once. The symptoms of viral diseases result from the immune response to the virus, which attempts to control and eliminate the virus from the body, and from cell damage caused by the virus. Many animal viruses, such as HIV (human immunodeficiency virus), leave the infected cells of the immune system by a process known as budding , where virions leave the cell individually. During the budding process, the cell does not undergo lysis and is not immediately killed. However, the damage to the cells that the virus infects may make it impossible for the cells to function normally, even though the cells remain alive for a period of time. Most productive viral infections follow similar steps in the virus replication cycle: attachment, penetration, uncoating, replication, assembly, and release ( Figure 21.8 ). Attachment A virus attaches to a specific receptor site on the host cell membrane through attachment proteins in the capsid or via glycoproteins embedded in the viral envelope. The specificity of this interaction determines the host—and the cells within the host—that can be infected by a particular virus. This can be illustrated by thinking of several keys and several locks, where each key will fit only one specific lock. Link to Learning This video explains how influenza attacks the body. Entry The nucleic acid of bacteriophages enters the host cell naked, leaving the capsid outside the cell. Plant and animal viruses can enter through endocytosis, in which the cell membrane surrounds and engulfs the entire virus. Some enveloped viruses enter the cell when the viral envelope fuses directly with the cell membrane. Once inside the cell, the viral capsid is degraded, and the viral nucleic acid is released, which then becomes available for replication and transcription. Replication and Assembly The replication mechanism depends on the viral genome. DNA viruses usually use host cell proteins and enzymes to make additional DNA that is transcribed to messenger RNA (mRNA), which is then used to direct protein synthesis. RNA viruses usually use the RNA core as a template for synthesis of viral genomic RNA and mRNA. The viral mRNA directs the host cell to synthesize viral enzymes and capsid proteins, and assemble new virions. Of course, there are exceptions to this pattern. If a host cell does not provide the enzymes necessary for viral replication, viral genes supply the information to direct synthesis of the missing proteins. Retroviruses, such as HIV, have an RNA genome that must be reverse transcribed into DNA, which then is incorporated into the host cell genome. They are within group VI of the Baltimore classification scheme. To convert RNA into DNA, retroviruses must contain genes that encode the virus-specific enzyme reverse transcriptase that transcribes an RNA template to DNA. Reverse transcription never occurs in uninfected host cells—the needed enzyme reverse transcriptase is only derived from the expression of viral genes within the infected host cells. The fact that HIV produces some of its own enzymes not found in the host has allowed researchers to develop drugs that inhibit these enzymes. These drugs, including the reverse transcriptase inhibitor AZT , inhibit HIV replication by reducing the activity of the enzyme without affecting the host’s metabolism. This approach has led to the development of a variety of drugs used to treat HIV and has been effective at reducing the number of infectious virions (copies of viral RNA) in the blood to non-detectable levels in many HIV-infected individuals. Egress The last stage of viral replication is the release of the new virions produced in the host organism, where they are able to infect adjacent cells and repeat the replication cycle. As you’ve learned, some viruses are released when the host cell dies, and other viruses can leave infected cells by budding through the membrane without directly killing the cell. Visual Connection Influenza virus is packaged in a viral envelope that fuses with the plasma membrane. This way, the virus can exit the host cell without killing it. What advantage does the virus gain by keeping the host cell alive? Link to Learning Watch a video on viruses, identifying structures, modes of transmission, replication, and more. Different Hosts and Their Viruses As you’ve learned, viruses are often very specific as to which hosts and which cells within the host they will infect. This feature of a virus makes it specific to one or a few species of life on Earth. On the other hand, so many different types of viruses exist on Earth that nearly every living organism has its own set of viruses that tries to infect its cells. Even the smallest and simplest of cells, prokaryotic bacteria, may be attacked by specific types of viruses. Bacteriophages Bacteriophages are viruses that infect bacteria ( Figure 21.9 ). When infection of a cell by a bacteriophage results in the production of new virions, the infection is said to be productive . If the virions are released by bursting the cell, the virus replicates by means of a lytic cycle ( Figure 21.10 ). An example of a lytic bacteriophage is T4, which infects Escherichia coli found in the human intestinal tract. Sometimes, however, a virus can remain within the cell without being released. For example, when a temperate bacteriophage infects a bacterial cell, it replicates by means of a lysogenic cycle ( Figure 21.10 ), and the viral genome is incorporated into the genome of the host cell. When the phage DNA is incorporated into the host cell genome, it is called a prophage . An example of a lysogenic bacteriophage is the λ (lambda) virus, which also infects the E . coli bacterium. Viruses that infect plant or animal cells may also undergo infections where they are not producing virions for long periods. An example is the animal herpesviruses, including herpes simplex viruses, the cause of oral and genital herpes in humans. In a process called latency , these viruses can exist in nervous tissue for long periods of time without producing new virions, only to leave latency periodically and cause lesions in the skin where the virus replicates. Even though there are similarities between lysogeny and latency, the term lysogenic cycle is usually reserved to describe bacteriophages. Latency will be described in more detail below. Visual Connection Which of the following statements is false? In the lytic cycle, new phage are produced and released into the environment. In the lysogenic cycle, phage DNA is incorporated into the host genome. An environmental stressor can cause the phage to initiate the lysogenic cycle. Cell lysis only occurs in the lytic cycle. Animal Viruses Animal viruses, unlike the viruses of plants and bacteria, do not have to penetrate a cell wall to gain access to the host cell. Non-enveloped or “naked” animal viruses may enter cells in two different ways. As a protein in the viral capsid binds to its receptor on the host cell, the virus may be taken inside the cell via a vesicle during the normal cell process of receptor-mediated endocytosis. An alternative method of cell penetration used by non-enveloped viruses is for capsid proteins to undergo shape changes after binding to the receptor, creating channels in the host cell membrane. The viral genome is then “injected” into the host cell through these channels in a manner analogous to that used by many bacteriophages. Enveloped viruses also have two ways of entering cells after binding to their receptors: receptor-mediated endocytosis, or fusion . Many enveloped viruses enter the cell by receptor-mediated endocytosis in a fashion similar to some non-enveloped viruses. On the other hand, fusion only occurs with enveloped virions. These viruses, which include HIV among others, use special fusion proteins in their envelopes to cause the envelope to fuse with the plasma membrane of the cell, thus releasing the genome and capsid of the virus into the cell cytoplasm. After making their proteins and copying their genomes, animal viruses complete the assembly of new virions and exit the cell. As we have already discussed using the example of HIV, enveloped animal viruses may bud from the cell membrane as they assemble themselves, taking a piece of the cell’s plasma membrane in the process. On the other hand, non-enveloped viral progeny, such as rhinoviruses, accumulate in infected cells until there is a signal for lysis or apoptosis, and all virions are released together. As you will learn in the next module, animal viruses are associated with a variety of human diseases. Some of them follow the classic pattern of acute disease , where symptoms get increasingly worse for a short period followed by the elimination of the virus from the body by the immune system and eventual recovery from the infection. Examples of acute viral diseases are the common cold and influenza. Other viruses cause long-term chronic infections , such as the virus causing hepatitis C, whereas others, like herpes simplex virus, only cause intermittent symptoms. Still other viruses, such as human herpesviruses 6 and 7, which in some cases can cause the minor childhood disease roseola, often successfully cause productive infections without causing any symptoms at all in the host, and thus we say these patients have an asymptomatic infection . In hepatitis C infections, the virus grows and reproduces in liver cells, causing low levels of liver damage. The damage is so low that infected individuals are often unaware that they are infected, and many infections are detected only by routine blood work on patients with risk factors such as intravenous drug use. On the other hand, since many of the symptoms of viral diseases are caused by immune responses, a lack of symptoms is an indication of a weak immune response to the virus. This allows for the virus to escape elimination by the immune system and persist in individuals for years, all the while producing low levels of progeny virions in what is known as a chronic viral disease. Chronic infection of the liver by this virus leads to a much greater chance of developing liver cancer, sometimes as much as 30 years after the initial infection. As already discussed, herpes simplex virus can remain in a state of latency in nervous tissue for months, even years. As the virus “hides” in the tissue and makes few if any viral proteins, there is nothing for the immune response to act against, and immunity to the virus slowly declines. Under certain conditions, including various types of physical and psychological stress, the latent herpes simplex virus may be reactivated and undergo a lytic replication cycle in the skin, causing the lesions associated with the disease. Once virions are produced in the skin and viral proteins are synthesized, the immune response is again stimulated and resolves the skin lesions in a few days by destroying viruses in the skin. As a result of this type of replicative cycle, appearances of cold sores and genital herpes outbreaks only occur intermittently, even though the viruses remain in the nervous tissue for life. Latent infections are common with other herpesviruses as well, including the varicella-zoster virus that causes chickenpox. After having a chickenpox infection in childhood, the varicella-zoster virus can remain latent for many years and reactivate in adults to cause the painful condition known as “shingles” ( Figure 21.11 ab ). Some animal-infecting viruses, including the hepatitis C virus discussed above, are known as oncogenic viruses : They have the ability to cause cancer. These viruses interfere with the normal regulation of the host cell cycle either by either introducing genes that stimulate unregulated cell growth (oncogenes) or by interfering with the expression of genes that inhibit cell growth. Oncogenic viruses can be either DNA or RNA viruses. Cancers known to be associated with viral infections include cervical cancer caused by human papillomavirus (HPV) ( Figure 21.12 ), liver cancer caused by hepatitis B virus, T-cell leukemia, and several types of lymphoma. Link to Learning Visit the interactive animations showing the various stages of the replicative cycles of animal viruses and click on the flash animation links. Plant Viruses Plant viruses, like other viruses, contain a core of either DNA or RNA. You have already learned about one of these, the tobacco mosaic virus. As plant cells have a cell wall to protect their cells, these viruses do not use receptor-mediated endocytosis to enter host cells as is seen with animal viruses. For many plant viruses to be transferred from plant to plant, damage to some of the plants’ cells must occur to allow the virus to enter a new host. This damage is often caused by weather, insects, animals, fire, or human activities like farming or landscaping. Additionally, plant offspring may inherit viral diseases from parent plants. Plant viruses can be transmitted by a variety of vectors, through contact with an infected plant’s sap, by living organisms such as insects and nematodes, and through pollen. When plants viruses are transferred between different plants, this is known as horizontal transmission , and when they are inherited from a parent, this is called vertical transmission . Symptoms of viral diseases vary according to the virus and its host ( Table 21.4 ). One common symptom is hyperplasia , the abnormal proliferation of cells that causes the appearance of plant tumors known as galls . Other viruses induce hypoplasia , or decreased cell growth, in the leaves of plants, causing thin, yellow areas to appear. Still other viruses affect the plant by directly killing plant cells, a process known as cell necrosis . Other symptoms of plant viruses include malformed leaves, black streaks on the stems of the plants, altered growth of stems, leaves, or fruits, and ring spots, which are circular or linear areas of discoloration found in a leaf. Some Common Symptoms of Plant Viral Diseases Symptom Appears as Hyperplasia Galls (tumors) Hypoplasia Thinned, yellow splotches on leaves Cell necrosis Dead, blackened stems, leaves, or fruit Abnormal growth patterns Malformed stems, leaves, or fruit Discoloration Yellow, red, or black lines, or rings in stems, leaves, or fruit Table 21.4 Plant viruses can seriously disrupt crop growth and development, significantly affecting our food supply. They are responsible for poor crop quality and quantity globally, and can bring about huge economic losses annually. Others viruses may damage plants used in landscaping. Some viruses that infect agricultural food plants include the name of the plant they infect, such as tomato spotted wilt virus, bean common mosaic virus, and cucumber mosaic virus. In plants used for landscaping, two of the most common viruses are peony ring spot and rose mosaic virus. There are far too many plant viruses to discuss each in detail, but symptoms of bean common mosaic virus result in lowered bean production and stunted, unproductive plants. In the ornamental rose, the rose mosaic disease causes wavy yellow lines and colored splotches on the leaves of the plant. 21.3 Prevention and Treatment of Viral Infections Learning Objectives By the end of this section, you will be able to: Identify major viral illnesses that affect humans Compare vaccinations and anti-viral drugs as medical approaches to viruses Viruses cause a variety of diseases in animals, including humans, ranging from the common cold to potentially fatal illnesses like meningitis ( Figure 21.13 ). These diseases can be treated by antiviral drugs or by vaccines, but some viruses, such as HIV, are capable of both avoiding the immune response and mutating to become resistant to antiviral drugs. Vaccines for Prevention While we do have limited numbers of effective antiviral drugs, such as those used to treat HIV and influenza, the primary method of controlling viral disease is by vaccination, which is intended to prevent outbreaks by building immunity to a virus or virus family ( Figure 21.14 ). Vaccines may be prepared using live viruses, killed viruses, or molecular subunits of the virus. The killed viral vaccines and subunit viruses are both incapable of causing disease. Live viral vaccines are designed in the laboratory to cause few symptoms in recipients while giving them protective immunity against future infections. Polio was one disease that represented a milestone in the use of vaccines. Mass immunization campaigns in the 1950s (killed vaccine) and 1960s (live vaccine) significantly reduced the incidence of the disease, which caused muscle paralysis in children and generated a great amount of fear in the general population when regional epidemics occurred. The success of the polio vaccine paved the way for the routine dispensation of childhood vaccines against measles, mumps, rubella, chickenpox, and other diseases. The danger of using live vaccines, which are usually more effective than killed vaccines, is the low but significant danger that these viruses will revert to their disease-causing form by back mutations . Live vaccines are usually made by attenuating (weakening) the “wild-type” (disease-causing) virus by growing it in the laboratory in tissues or at temperatures different from what the virus is accustomed to in the host. Adaptations to these new cells or temperatures induce mutations in the genomes of the virus, allowing it to grow better in the laboratory while inhibiting its ability to cause disease when reintroduced into conditions found in the host. These attenuated viruses thus still cause infection, but they do not grow very well, allowing the immune response to develop in time to prevent major disease. Back mutations occur when the vaccine undergoes mutations in the host such that it readapts to the host and can again cause disease, which can then be spread to other humans in an epidemic. This type of scenario happened as recently as 2007 in Nigeria where mutations in a polio vaccine led to an epidemic of polio in that country. Some vaccines are in continuous development because certain viruses, such as influenza and HIV, have a high mutation rate compared to other viruses and normal host cells. With influenza, mutations in the surface molecules of the virus help the organism evade the protective immunity that may have been obtained in a previous influenza season, making it necessary for individuals to get vaccinated every year. Other viruses, such as those that cause the childhood diseases measles, mumps, and rubella, mutate so infrequently that the same vaccine is used year after year. Link to Learning Watch this NOVA video to learn how microbiologists are attempting to replicate the deadly 1918 Spanish influenza virus so they can understand more about virology. Vaccines and Anti-viral Drugs for Treatment In some cases, vaccines can be used to treat an active viral infection. The concept behind this is that by giving the vaccine, immunity is boosted without adding more disease-causing virus. In the case of rabies, a fatal neurological disease transmitted via the saliva of rabies virus-infected animals, the progression of the disease from the time of the animal bite to the time it enters the central nervous system may be 2 weeks or longer. This is enough time to vaccinate an individual who suspects that they have been bitten by a rabid animal, and their boosted immune response is sufficient to prevent the virus from entering nervous tissue. Thus, the potentially fatal neurological consequences of the disease are averted, and the individual only has to recover from the infected bite. This approach is also being used for the treatment of Ebola, one of the fastest and most deadly viruses on earth. Transmitted by bats and great apes, this disease can cause death in 70–90 percent of infected humans within 2 weeks. Using newly developed vaccines that boost the immune response in this way, there is hope that affected individuals will be better able to control the virus, potentially saving a greater percentage of infected persons from a rapid and very painful death. Another way of treating viral infections is the use of antiviral drugs. These drugs often have limited success in curing viral disease, but in many cases, they have been used to control and reduce symptoms for a wide variety of viral diseases. For most viruses, these drugs can inhibit the virus by blocking the actions of one or more of its proteins. It is important that the targeted proteins be encoded by viral genes and that these molecules are not present in a healthy host cell. In this way, viral growth is inhibited without damaging the host. There are large numbers of antiviral drugs available to treat infections, some specific for a particular virus and others that can affect multiple viruses. Antivirals have been developed to treat genital herpes (herpes simplex II) and influenza. For genital herpes, drugs such as acyclovir can reduce the number and duration of episodes of active viral disease, during which patients develop viral lesions in their skin cells. As the virus remains latent in nervous tissue of the body for life, this drug is not curative but can make the symptoms of the disease more manageable. For influenza, drugs like Tamiflu (oseltamivir) ( Figure 21.15 ) can reduce the duration of “flu” symptoms by 1 or 2 days, but the drug does not prevent symptoms entirely. Tamiflu works by inhibiting an enzyme (viral neuraminidase) that allows new virions to leave their infected cells. Thus, Tamiflu inhibits the spread of virus from infected to uninfected cells. Other antiviral drugs, such as Ribavirin, have been used to treat a variety of viral infections, although its mechanism of action against certain viruses remains unclear. By far, the most successful use of antivirals has been in the treatment of the retrovirus HIV, which causes a disease that, if untreated, is usually fatal within 10–12 years after infection. Anti-HIV drugs have been able to control viral replication to the point that individuals receiving these drugs survive for a significantly longer time than the untreated. Anti-HIV drugs inhibit viral replication at many different phases of the HIV replicative cycle ( Figure 21.16 ). Drugs have been developed that inhibit the fusion of the HIV viral envelope with the plasma membrane of the host cell (fusion inhibitors), the conversion of its RNA genome into double-stranded DNA (reverse transcriptase inhibitors), the integration of the viral DNA into the host genome (integrase inhibitors), and the processing of viral proteins (protease inhibitors). When any of these drugs are used individually, the high mutation rate of the virus allows it to easily and rapidly develop resistance to the drug, limiting the drug’s effectiveness. The breakthrough in the treatment of HIV was the development of HAART, highly active anti-retroviral therapy, which involves a mixture of different drugs, sometimes called a drug “cocktail.” By attacking the virus at different stages of its replicative cycle, it is much more difficult for the virus to develop resistance to multiple drugs at the same time. Still, even with the use of combination HAART therapy, there is concern that, over time, the virus will develop resistance to this therapy. Thus, new anti-HIV drugs are constantly being developed with the hope of continuing the battle against this highly fatal virus. Everyday Connection Applied Virology The study of viruses has led to the development of a variety of new ways to treat non-viral diseases. Viruses have been used in gene therapy . Gene therapy is used to treat genetic diseases such as severe combined immunodeficiency (SCID), a heritable, recessive disease in which children are born with severely compromised immune systems. One common type of SCID is due to the lack of an enzyme, adenosine deaminase (ADA), which breaks down purine bases. To treat this disease by gene therapy, bone marrow cells are taken from a SCID patient and the ADA gene is inserted. This is where viruses come in, and their use relies on their ability to penetrate living cells and bring genes in with them. Viruses such as adenovirus, an upper respiratory human virus, are modified by the addition of the ADA gene, and the virus then transports this gene into the cell. The modified cells, now capable of making ADA, are then given back to the patients in the hope of curing them. Gene therapy using viruses as carrier of genes (viral vectors), although still experimental, holds promise for the treatment of many genetic diseases. Still, many technological problems need to be solved for this approach to be a viable method for treating genetic disease. Another medical use for viruses relies on their specificity and ability to kill the cells they infect. Oncolytic viruses are engineered in the laboratory specifically to attack and kill cancer cells. A genetically modified adenovirus known as H101 has been used since 2005 in clinical trials in China to treat head and neck cancers. The results have been promising, with a greater short-term response rate to the combination of chemotherapy and viral therapy than to chemotherapy treatment alone. This ongoing research may herald the beginning of a new age of cancer therapy, where viruses are engineered to find and specifically kill cancer cells, regardless of where in the body they may have spread. A third use of viruses in medicine relies on their specificity and involves using bacteriophages in the treatment of bacterial infections. Bacterial diseases have been treated with antibiotics since the 1940s. However, over time, many bacteria have developed resistance to antibiotics. A good example is methicillin-resistant Staphylococcus aureus (MRSA, pronounced “mersa”), an infection commonly acquired in hospitals. This bacterium is resistant to a variety of antibiotics, making it difficult to treat. The use of bacteriophages specific for such bacteria would bypass their resistance to antibiotics and specifically kill them. Although phage therapy is in use in the Republic of Georgia to treat antibiotic-resistant bacteria, its use to treat human diseases has not been approved in most countries. However, the safety of the treatment was confirmed in the United States when the U.S. Food and Drug Administration approved spraying meats with bacteriophages to destroy the food pathogen Listeria. As more and more antibiotic-resistant strains of bacteria evolve, the use of bacteriophages might be a potential solution to the problem, and the development of phage therapy is of much interest to researchers worldwide. 21.4 Other Acellular Entities: Prions and Viroids Learning Objectives By the end of this section, you will be able to: Describe prions and their basic properties Define viroids and their targets of infection Prions and viroids are pathogens (agents with the ability to cause disease) that have simpler structures than viruses but, in the case of prions, still can produce deadly diseases. Prions Prions , so-called because they are proteinaceous, are infectious particles—smaller than viruses—that contain no nucleic acids (neither DNA nor RNA). Historically, the idea of an infectious agent that did not use nucleic acids was considered impossible, but pioneering work by Nobel Prize-winning biologist Stanley Prusiner has convinced the majority of biologists that such agents do indeed exist. Fatal neurodegenerative diseases, such as kuru in humans and bovine spongiform encephalopathy (BSE) in cattle (commonly known as “mad cow disease”) were shown to be transmitted by prions. The disease was spread by the consumption of meat, nervous tissue, or internal organs between members of the same species. Kuru, native to humans in Papua New Guinea, was spread from human to human via ritualistic cannibalism. BSE, originally detected in the United Kingdom, was spread between cattle by the practice of including cattle nervous tissue in feed for other cattle. Individuals with kuru and BSE show symptoms of loss of motor control and unusual behaviors, such as uncontrolled bursts of laughter with kuru, followed by death. Kuru was controlled by inducing the population to abandon its ritualistic cannibalism. On the other hand, BSE was initially thought to only affect cattle. Cattle dying of the disease were shown to have developed lesions or “holes” in the brain, causing the brain tissue to resemble a sponge. Later on in the outbreak, however, it was shown that a similar encephalopathy in humans known as variant Creutzfeldt-Jakob disease (CJD) could be acquired from eating beef from animals with BSE, sparking bans by various countries on the importation of British beef and causing considerable economic damage to the British beef industry ( Figure 21.17 ). BSE still exists in various areas, and although a rare disease, individuals that acquire CJD are difficult to treat. The disease can be spread from human to human by blood, so many countries have banned blood donation from regions associated with BSE. The cause of spongiform encephalopathies, such as kuru and BSE, is an infectious structural variant of a normal cellular protein called PrP (prion protein). It is this variant that constitutes the prion particle. PrP exists in two forms, PrP c , the normal form of the protein, and PrP sc , the infectious form. Once introduced into the body, the PrP sc contained within the prion binds to PrP c and converts it to PrP sc . This leads to an exponential increase of the PrP sc protein, which aggregates. PrP sc is folded abnormally, and the resulting conformation (shape) is directly responsible for the lesions seen in the brains of infected cattle. Thus, although not without some detractors among scientists, the prion seems likely to be an entirely new form of infectious agent, the first one found whose transmission is not reliant upon genes made of DNA or RNA. Viroids Viroids are plant pathogens: small, single-stranded, circular RNA particles that are much simpler than a virus. They do not have a capsid or outer envelope, but like viruses can reproduce only within a host cell. Viroids do not, however, manufacture any proteins, and they only produce a single, specific RNA molecule. Human diseases caused by viroids have yet to be identified. Viroids are known to infect plants ( Figure 21.18 ) and are responsible for crop failures and the loss of millions of dollars in agricultural revenue each year. Some of the plants they infect include potatoes, cucumbers, tomatoes, chrysanthemums, avocados, and coconut palms. Career Connection Virologist Virology is the study of viruses, and a virologist is an individual trained in this discipline. Training in virology can lead to many different career paths. Virologists are actively involved in academic research and teaching in colleges and medical schools. Some virologists treat patients or are involved in the generation and production of vaccines. They might participate in epidemiologic studies ( Figure 21.19 ) or become science writers, to name just a few possible careers. If you think you may be interested in a career in virology, find a mentor in the field. Many large medical centers have departments of virology, and smaller hospitals usually have virology labs within their microbiology departments. Volunteer in a virology lab for a semester or work in one over the summer. Discussing the profession and getting a first-hand look at the work will help you decide whether a career in virology is right for you. The American Society of Virology’s website is a good resource for information regarding training and careers in virology.
american_government
Summary 6.1 The Nature of Public Opinion Public opinion is more than a collection of answers to a question on a poll; it represents a snapshot of how people’s experiences and beliefs have led them to feel about a candidate, a law, or a social issue. Our attitudes are formed in childhood as part of our upbringing. They blend with our closely held beliefs about life and politics to form the basis for our opinions. Beginning early in life, we learn about politics from agents of socialization, which include family, schools, friends, religious organizations, and the media. Socialization gives us the information necessary to understand our political system and make decisions. We use this information to choose our ideology and decide what the proper role of government should be in our society. 6.2 How Is Public Opinion Measured? The purpose of a poll is to identify how a population feels about an issue or candidate. Many polling companies and news outlets use statisticians and social scientists to design accurate and scientific polls and to reduce errors. A scientific poll will try to create a representative and random sample to ensure the responses are similar to what the actual population of an area believes. Scientific polls also have lower margins of error, which means they better predict what the overall public or population thinks. Most polls are administered through phones, online, or via social media. Even in scientific polls, issues like timing, social pressure, lack of knowledge, and human nature can create results that do not match true public opinion. Polls can also be used as campaign devices to try to change a voter’s mind on an issue or candidate. 6.3 What Does the Public Think? When citizens change their sources of information, their opinions may change. The influence of elites and workplaces, life experiences, and state political culture can all help change our opinions. Economic and social policies are likely to cause controversy if the government has to serve the needs of many different groups or balance rights and liberties, all with limited resources. What Americans think about their government institutions shifts over time as well. Overall approval for presidents begins high and drops over time, with expected increases and decreases occurring due to domestic and international events. Approval for Congress changes more dramatically with domestic events and partisan behavior. The public has a lower opinion of Congress than of the president, and recent congressional approval levels have hovered between 10 and 20 percent. The Supreme Court has the most stable public approval ratings, possibly due to its less visible nature. But the court’s ratings can be affected by controversial decisions, such as its 2015 decisions on the Affordable Care Act and same-sex marriage. 6.4 The Effects of Public Opinion Public opinion polls have some effect on politics, most strongly during election season. Candidates who do well in polls receive more media coverage and campaign donations than candidates who fare poorly. The effect of polling on government institutions is less clear. Presidents sometimes consider polls when making decisions, especially if the polls reflect high approval. A president who has an electoral mandate can use that high public approval rating to push policies through Congress. Congress is likely to be aware of public opinion on issues. Representatives must continually raise campaign donations for bi-yearly elections. For this reason, they must keep their constituents and donors happy. Representatives are also likely to change their voting behavior if public opinion changes. Senators have a longer span between elections, which gives them time to make decisions independent of opinion and then make amends with their constituents. Changes in public opinion do not affect senators’ votes, but they do cause senators to lose reelection. It is less clear whether Supreme Court justices rule in ways that maintain the integrity of the branch or that keep step with the majority opinion of the public, but public approval of the court can change after high-profile decisions.
Chapter Outline 6.1 The Nature of Public Opinion 6.2 How Is Public Opinion Measured? 6.3 What Does the Public Think? 6.4 The Effects of Public Opinion Introduction On November 7, 2012, the day after the presidential election, journalists found Mitt Romney’s transition website, detailing the Republican candidate’s plans for the upcoming inauguration celebration and criteria for Cabinet and White House appointees and leaving space for video of his acceptance speech. 1 Yet, Romney had lost his bid for the White House. Romney’s campaign staff had been so sure he would win that he had not written a concession speech. How could they have been wrong? Romney’s staff blamed the campaign’s own polls. The staff believed Republican voters were highly motivated, leading Romney pollsters to overestimate how many would turn out ( Figure 6.1 ). 2 The campaign’s polls showed Romney close to President Barack Obama, although non-campaign polls showed Obama ahead. 3 On election night, Romney gave his hastily drafted concession speech, still unsure how he had lost. In the 2016 election, most polls showed Democratic nominee Hillary Clinton with an advantage nationwide and in the battleground states in the days leading up to the election. However, Republican nominee Donald Trump was elected president as many new voters joined the process, voters who were not studied in the polls as likely voters. As many a disappointed candidate knows, public opinion matters. The way opinions are formed and the way we measure public opinion also matter. But how much, and why? These are some of the questions we’ll explore in this chapter.
[ { "answer": { "ans_choice": 3, "ans_text": "D" }, "bloom": null, "hl_context": "<hl> The most prominent agents of socialization are family and school . <hl> <hl> Other influential agents are social groups , such as religious institutions and friends , and the media . <hl> Political socialization is not unique to the United States . Many nations have realized the benefits of socializing their populations . China , for example , stresses nationalism in schools as a way to increase national unity . 17 In the United States , one benefit of socialization is that our political system enjoys diffuse support , which is support characterized by a high level of stability in politics , acceptance of the government as legitimate , and a common goal of preserving the system . 18 These traits keep a country steady , even during times of political or social upheaval . But diffuse support does not happen quickly , nor does it occur without the help of agents of political socialization .", "hl_sentences": "The most prominent agents of socialization are family and school . Other influential agents are social groups , such as religious institutions and friends , and the media .", "question": { "cloze_format": "___ is not an agent of political socialization.", "normal_format": "Which of the following is not an agent of political socialization?", "question_choices": [ "a family member", "a religious leader", "a teacher", "a U.S. senator" ], "question_id": "fs-id1163758388110", "question_text": "Which of the following is not an agent of political socialization?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 1, "ans_text": "in childhood, based on early childhood experiences" }, "bloom": null, "hl_context": "But where do people ’ s opinions come from ? <hl> Most citizens base their political opinions on their beliefs 5 and their attitudes , both of which begin to form in childhood . <hl> Beliefs are closely held ideas that support our values and expectations about life and politics . For example , the idea that we are all entitled to equality , liberty , freedom , and privacy is a belief most people in the United States share . We may acquire this belief by growing up in the United States or by having come from a country that did not afford these valued principles to its citizens .", "hl_sentences": "Most citizens base their political opinions on their beliefs 5 and their attitudes , both of which begin to form in childhood .", "question": { "cloze_format": "Most attitudes are formed ___ .", "normal_format": "How are most attitudes formed?", "question_choices": [ "in adulthood, based on life choices", "in childhood, based on early childhood experiences", "in college, based on classes and majors", "after college, based on finances" ], "question_id": "fs-id1163758490485", "question_text": "How are most attitudes formed?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 0, "ans_text": "A" }, "bloom": null, "hl_context": "Finally , media information presented as fact can contain covert or overt political material . Covert content is political information provided under the pretense that it is neutral . A magazine might run a story on climate change by interviewing representatives of only one side of the policy debate and downplaying the opposing view , all without acknowledging the one-sided nature of its coverage . <hl> In contrast , when the writer or publication makes clear to the reader or viewer that the information offers only one side of the political debate , the political message is overt content . <hl> Political commentators like Rush Limbaugh and publications like Mother Jones openly state their ideological viewpoints . While such overt political content may be offensive or annoying to a reader or viewer , all are offered the choice whether to be exposed to the material .", "hl_sentences": "In contrast , when the writer or publication makes clear to the reader or viewer that the information offers only one side of the political debate , the political message is overt content .", "question": { "cloze_format": "________ political content is given by a media source that lets the reader or viewer know upfront there is a political bias or position.", "normal_format": "Which political content is given by a media source that lets the reader or viewer know upfront there is a political bias or position?", "question_choices": [ "Overt", "Covert", "Explanatory", "Expository" ], "question_id": "fs-id1163758473471", "question_text": "________ political content is given by a media source that lets the reader or viewer know upfront there is a political bias or position." }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 2, "ans_text": "say they will vote for a candidate but then vote against him or her" }, "bloom": null, "hl_context": "People may also feel social pressure to answer questions in accordance with the norms of their area or peers . 39 If they are embarrassed to admit how they would vote , they may lie to the interviewer . In the 1982 governor ’ s race in California , Tom Bradley was far ahead in the polls , yet on Election Day he lost . <hl> This result was nicknamed the Bradley effect , on the theory that voters who answered the poll were afraid to admit they would not vote for a black man because it would appear politically incorrect and racist . <hl> In the 2016 presidential election , the level of support for Republican nominee Donald Trump may have been artificially low in the polls due to the fact that some respondents did not want to admit they were voting for Trump .", "hl_sentences": "This result was nicknamed the Bradley effect , on the theory that voters who answered the poll were afraid to admit they would not vote for a black man because it would appear politically incorrect and racist .", "question": { "cloze_format": "The Bradley effect occurs when people ________.", "normal_format": "The Bradley effect occurs when people do what?", "question_choices": [ "say they will vote for a candidate based on the candidate’s name", "say they will vote against a candidate because of the candidate’s race", "say they will vote for a candidate but then vote against him or her", "say they will vote in the next election but instead stay home" ], "question_id": "fs-id1163757311228", "question_text": "The Bradley effect occurs when people ________." }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 0, "ans_text": "A" }, "bloom": null, "hl_context": "With many polls out there , how do you know whether a poll is a good poll and accurately predicts what a group believes ? First , look for the numbers . Polling companies include the margin of error , polling dates , number of respondents , and population sampled to show their scientific reliability . Was the poll recently taken ? Is the question clear and unbiased ? Was the number of respondents high enough to predict the population ? <hl> Is the margin of error small ? <hl> It is worth looking for this valuable information when you interpret poll results . <hl> While most polling agencies strive to create quality polls , other organizations want fast results and may prioritize immediate numbers over random and representative samples . <hl> For example , instant polling is often used by news networks to quickly assess how well candidates are performing in a debate .", "hl_sentences": "Is the margin of error small ? While most polling agencies strive to create quality polls , other organizations want fast results and may prioritize immediate numbers over random and representative samples .", "question": { "cloze_format": "___ is not part of a scientific poll design.", "normal_format": "Which of the following is not part of a scientific poll design?", "question_choices": [ "a leading question", "a random sample", "a representative sample", "a low margin of error" ], "question_id": "fs-id1163757293877", "question_text": "Which of the following is not part of a scientific poll design?" }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 2, "ans_text": "It is a non-representative poll and the margin of error is too high." }, "bloom": null, "hl_context": "When the sample represents the actual population , the poll ’ s accuracy will be reflected in a lower margin of error . The margin of error is a number that states how far the poll results may be from the actual opinion of the total population of citizens . The lower the margin of error , the more predictive the poll . Large margins of error are problematic . <hl> For example , if a poll that claims Hillary Clinton is likely to win 30 percent of the vote in the 2016 New York Democratic primary has a margin of error of + / - 6 , it tells us that Clinton may receive as little as 24 percent of the vote ( 30 – 6 ) or as much as 36 percent ( 30 + 6 ) . <hl> <hl> A lower of margin of error is clearly desirable because it gives us the most precise picture of what people actually think or will do . <hl>", "hl_sentences": "For example , if a poll that claims Hillary Clinton is likely to win 30 percent of the vote in the 2016 New York Democratic primary has a margin of error of + / - 6 , it tells us that Clinton may receive as little as 24 percent of the vote ( 30 – 6 ) or as much as 36 percent ( 30 + 6 ) . A lower of margin of error is clearly desirable because it gives us the most precise picture of what people actually think or will do .", "question": { "cloze_format": "A poll states that Hillary Clinton will receive 43 percent of the vote. There is an 8 percent margin of error. I think of the poll that ___.", "normal_format": "A poll states that Hillary Clinton will receive 43 percent of the vote. There is an 8 percent margin of error. What do you think of the poll?", "question_choices": [ "It is a good poll and the margin of error is small.", "It is a good poll and the margin of error is acceptable.", "It is a non-representative poll and the margin of error is too high.", "The poll accurately predicts Clinton will receive 43 percent of the vote." ], "question_id": "fs-id1163757181959", "question_text": "A poll states that Hillary Clinton will receive 43 percent of the vote. There is an 8 percent margin of error. What do you think of the poll?" }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 1, "ans_text": "B" }, "bloom": null, "hl_context": "<hl> Social policy consists of government ’ s attempts to regulate public behavior in the service of a better society . <hl> <hl> To accomplish this , government must achieve the difficult task of balancing the rights and liberties of citizens . <hl> A person ’ s right to privacy , for example , might need to be limited if another person is in danger . But to what extent should the government intrude in the private lives of its citizens ? In a recent survey , 54 percent of respondents believed the U . S . government was too involved in trying to deal with issues of morality . 58", "hl_sentences": "Social policy consists of government ’ s attempts to regulate public behavior in the service of a better society . To accomplish this , government must achieve the difficult task of balancing the rights and liberties of citizens .", "question": { "cloze_format": "Social policies are controversial because ___.", "normal_format": "Why are social policies controversial?", "question_choices": [ "They require people to accept the authority of the government.", "They require government to balance the rights and liberties of different groups.", "They require the government to increase spending.", "They require a decrease in regulations and laws." ], "question_id": "fs-id1163758474793", "question_text": "Why are social policies controversial?" }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 3, "ans_text": "domestic events" }, "bloom": null, "hl_context": "<hl> While presidents are affected by foreign and domestic events , congressional approval is mainly affected by domestic events . <hl> When the economy rebounds or gas prices drop , public approval of Congress tends to go up . But when party politics within Congress becomes a domestic event , public approval falls . The passage of revenue bills has become an example of such an event , because deficits require Congress to make policy decisions before changing the budget . Deficit and debt are not new to the United States . Congress and presidents have attempted various methods of controlling debt , sometimes successfully and sometimes not . In the past three decades alone , however , several prominent examples have shown how party politics make it difficult for Congress to agree on a budget without a fight , and how these fights affect public approval .", "hl_sentences": "While presidents are affected by foreign and domestic events , congressional approval is mainly affected by domestic events .", "question": { "cloze_format": "The factor that affects congressional approval ratings the most is ___.", "normal_format": "Which factor affects congressional approval ratings the most?", "question_choices": [ "presidential actions", "foreign events", "Supreme Court actions", "domestic events" ], "question_id": "fs-id1163758409649", "question_text": "Which factor affects congressional approval ratings the most?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 3, "ans_text": "D" }, "bloom": null, "hl_context": "The Supreme Court generally enjoys less visibility than the other two branches of government , which leads to more stable but also less frequent polling results . Indeed , 22 percent of citizens surveyed in 2014 had never heard of Chief Justice John Roberts , the head of the Supreme Court . <hl> 75 The court is protected by the justices ’ non-elected , non-political positions , which gives them the appearance of integrity and helps the Supreme Court earn higher public approval ratings than presidents and Congress . <hl> To compare , between 2000 and 2010 , the court ’ s approval rating bounced between 50 and 60 percent . During this same period , Congress had a 20 to 40 percent approval rating .", "hl_sentences": "75 The court is protected by the justices ’ non-elected , non-political positions , which gives them the appearance of integrity and helps the Supreme Court earn higher public approval ratings than presidents and Congress .", "question": { "cloze_format": "The institution that has the highest average public approval ratings is ___.", "normal_format": "Which institution has the highest average public approval ratings?", "question_choices": [ "the presidency", "the U.S. House of Representatives", "the U.S. Senate", "the Supreme Court" ], "question_id": "fs-id1163758486205", "question_text": "Which institution has the highest average public approval ratings?" }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 1, "ans_text": "Polls tell voters the issues that candidates support." }, "bloom": null, "hl_context": "A : We choose our topics in several ways . <hl> Most importantly , we keep up with developments in politics and public policy , and try to make our polls reflect relevant issues . <hl> Much of our research is driven by the news cycle and topics that we see arising in the near future .", "hl_sentences": "Most importantly , we keep up with developments in politics and public policy , and try to make our polls reflect relevant issues .", "question": { "cloze_format": "Polls affect presidential elections because ___ .", "normal_format": "How do polls affect presidential elections?", "question_choices": [ "Polls help voters research information about each of the candidates.", "Polls tell voters the issues that candidates support.", "Polls identify the top candidates and the media interview those candidates.", "Polls explain which candidates should win the election." ], "question_id": "fs-id1163757191039", "question_text": "How do polls affect presidential elections?" }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 1, "ans_text": "B" }, "bloom": null, "hl_context": "The president is the most visible member of the U . S . government and a lightning rod for disagreement . <hl> Presidents are often blamed for the decisions of their administrations and political parties , and are held accountable for economic and foreign policy downturns . <hl> <hl> For these reasons , they can expect their approval ratings to slowly decline over time , increasing or decreasing slightly with specific events . <hl> On average , presidents enjoy a 66 percent approval rating when starting office , but it drops to 53 percent by the end of the first term . Presidents serving a second term average a beginning approval rating of 55.5 percent , which falls to 47 percent by the end of office . President Obama ’ s presidency followed the same trend . He entered office with a public approval rating of 67 percent , which fell to 54 percent by the third quarter , dropped to 52 percent after his reelection , and , as of the presidential election in November 2016 , was at 46 percent ( Figure 6.15 ) .", "hl_sentences": "Presidents are often blamed for the decisions of their administrations and political parties , and are held accountable for economic and foreign policy downturns . For these reasons , they can expect their approval ratings to slowly decline over time , increasing or decreasing slightly with specific events .", "question": { "cloze_format": "Presidential approval ratings ________ over a president’s term of office.", "normal_format": "What do presidential approval ratings do over a president’s term of office?", "question_choices": [ "increase", "decline", "stay relatively stable", "seesaw" ], "question_id": "fs-id1163757407597", "question_text": "Presidential approval ratings ________ over a president’s term of office." }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 3, "ans_text": "U.S. Supreme Court" }, "bloom": null, "hl_context": "There is some disagreement about whether the Supreme Court follows public opinion or shapes it . The lifetime tenure the justices enjoy was designed to remove everyday politics from their decisions , protect them from swings in political partisanship , and allow them to choose whether and when to listen to public opinion . <hl> More often than not , the public is unaware of the Supreme Court ’ s decisions and opinions . <hl> <hl> When the justices accept controversial cases , the media tune in and ask questions , raising public awareness and affecting opinion . <hl> <hl> But do the justices pay attention to the polls when they make decisions ? <hl>", "hl_sentences": "More often than not , the public is unaware of the Supreme Court ’ s decisions and opinions . When the justices accept controversial cases , the media tune in and ask questions , raising public awareness and affecting opinion . But do the justices pay attention to the polls when they make decisions ?", "question": { "cloze_format": "___ is the body of government that is least susceptible to public opinion polls.", "normal_format": "Which body of government is least susceptible to public opinion polls?", "question_choices": [ "the president", "U.S. Senate", "U.S. House of Representatives", "U.S. Supreme Court" ], "question_id": "fs-id1163757185813", "question_text": "Which body of government is least susceptible to public opinion polls?" }, "references_are_paraphrase": null } ]
6
6.1 The Nature of Public Opinion Learning Objectives By the end of this section, you will be able to: Define public opinion and political socialization Explain the process and role of political socialization in the U.S. political system Compare the ways in which citizens learn political information Explain how beliefs and ideology affect the formation of public opinion The collection of public opinion through polling and interviews is a part of American political culture. Politicians want to know what the public thinks. Campaign managers want to know how citizens will vote. Media members seek to write stories about what Americans want. Every day, polls take the pulse of the people and report the results. And yet we have to wonder: Why do we care what people think? WHAT IS PUBLIC OPINION? Public opinion is a collection of popular views about something, perhaps a person, a local or national event, or a new idea. For example, each day, a number of polling companies call Americans at random to ask whether they approve or disapprove of the way the president is guiding the economy. 4 When situations arise internationally, polling companies survey whether citizens support U.S. intervention in places like Syria or Ukraine. These individual opinions are collected together to be analyzed and interpreted for politicians and the media. The analysis examines how the public feels or thinks, so politicians can use the information to make decisions about their future legislative votes, campaign messages, or propaganda. But where do people’s opinions come from? Most citizens base their political opinions on their beliefs 5 and their attitudes, both of which begin to form in childhood. Beliefs are closely held ideas that support our values and expectations about life and politics. For example, the idea that we are all entitled to equality, liberty, freedom, and privacy is a belief most people in the United States share. We may acquire this belief by growing up in the United States or by having come from a country that did not afford these valued principles to its citizens. Our attitudes are also affected by our personal beliefs and represent the preferences we form based on our life experiences and values. A person who has suffered racism or bigotry may have a skeptical attitude toward the actions of authority figures, for example. Over time, our beliefs and our attitudes about people, events, and ideas will become a set of norms, or accepted ideas, about what we may feel should happen in our society or what is right for the government to do in a situation. In this way, attitudes and beliefs form the foundation for opinions. POLITICAL SOCIALIZATION At the same time that our beliefs and attitudes are forming during childhood, we are also being socialized ; that is, we are learning from many information sources about the society and community in which we live and how we are to behave in it. Political socialization is the process by which we are trained to understand and join a country’s political world, and, like most forms of socialization, it starts when we are very young. We may first become aware of politics by watching a parent or guardian vote, for instance, or by hearing presidents and candidates speak on television or the Internet, or seeing adults honor the American flag at an event ( Figure 6.2 ). As socialization continues, we are introduced to basic political information in school. We recite the Pledge of Allegiance and learn about the Founding Fathers, the Constitution, the two major political parties, the three branches of government, and the economic system. By the time we complete school, we have usually acquired the information necessary to form political views and be contributing members of the political system. A young man may realize he prefers the Democratic Party because it supports his views on social programs and education, whereas a young woman may decide she wants to vote for the Republican Party because its platform echoes her beliefs about economic growth and family values. Accounting for the process of socialization is central to our understanding of public opinion, because the beliefs we acquire early in life are unlikely to change dramatically as we grow older. 6 Our political ideology, made up of the attitudes and beliefs that help shape our opinions on political theory and policy, is rooted in who we are as individuals. Our ideology may change subtly as we grow older and are introduced to new circumstances or new information, but our underlying beliefs and attitudes are unlikely to change very much, unless we experience events that profoundly affect us. For example, family members of 9/11 victims became more Republican and more political following the terrorist attacks. 7 Similarly, young adults who attended political protest rallies in the 1960s and 1970s were more likely to participate in politics in general than their peers who had not protested. 8 If enough beliefs or attitudes are shattered by an event, such as an economic catastrophe or a threat to personal safety, ideology shifts may affect the way we vote. During the 1920s, the Republican Party controlled the House of Representatives and the Senate, sometimes by wide margins. 9 After the stock market collapsed and the nation slid into the Great Depression, many citizens abandoned the Republican Party. In 1932, voters overwhelmingly chose Democratic candidates, for both the presidency and Congress. The Democratic Party gained registered members and the Republican Party lost them. 10 Citizens’ beliefs had shifted enough to cause the control of Congress to change from one party to the other, and Democrats continued to hold Congress for several decades. Another sea change occurred in Congress in the 1994 elections when the Republican Party took control of both the House and the Senate for the first time in over forty years. Today, polling agencies have noticed that citizens’ beliefs have become far more polarized, or widely opposed, over the last decade. 11 To track this polarization, Pew Research conducted a study of Republican and Democratic respondents over a twenty-five-year span. Every few years, Pew would poll respondents, asking them whether they agreed or disagreed with statements. These statements are referred to as “value questions” or “value statements,” because they measure what the respondent values. Examples of statements include “Government regulation of business usually does more harm than good,” “Labor unions are necessary to protect the working person,” and “Society should ensure all have equal opportunity to succeed.” After comparing such answers for twenty-five years, Pew Research found that Republican and Democratic respondents are increasingly answering these questions very differently. This is especially true for questions about the government and politics. In 1987, 58 percent of Democrats and 60 percent of Republicans agreed with the statement that the government controlled too much of our daily lives. In 2012, 47 percent of Democrats and 77 percent of Republicans agreed with the statement. This is an example of polarization, in which members of one party see government from a very different perspective than the members of the other party ( Figure 6.3 ). 12 Political scientists noted this and other changes in beliefs following the 9/11 terrorist attacks on the United States, including an increase in the level of trust in government 13 and a new willingness to limit liberties for groups or citizens who “[did] not fit into the dominant cultural type.” 14 According to some scholars, these shifts led partisanship to become more polarized than in previous decades, as more citizens began thinking of themselves as conservative or liberal rather than moderate. 15 Some believe 9/11 caused a number of citizens to become more conservative overall, although it is hard to judge whether such a shift will be permanent. 16 SOCIALIZATION AGENTS An agent of political socialization is a source of political information intended to help citizens understand how to act in their political system and how to make decisions on political matters. The information may help a citizen decide how to vote, where to donate money, or how to protest decisions made by the government. The most prominent agents of socialization are family and school. Other influential agents are social groups, such as religious institutions and friends, and the media. Political socialization is not unique to the United States. Many nations have realized the benefits of socializing their populations. China, for example, stresses nationalism in schools as a way to increase national unity. 17 In the United States, one benefit of socialization is that our political system enjoys diffuse support , which is support characterized by a high level of stability in politics, acceptance of the government as legitimate, and a common goal of preserving the system. 18 These traits keep a country steady, even during times of political or social upheaval. But diffuse support does not happen quickly, nor does it occur without the help of agents of political socialization. For many children, family is the first introduction to politics. Children may hear adult conversations at home and piece together the political messages their parents support. They often know how their parents or grandparents plan to vote, which in turn can socialize them into political behavior such as political party membership. 19 Children who accompany their parents on Election Day in November are exposed to the act of voting and the concept of civic duty, which is the performance of actions that benefit the country or community. Families active in community projects or politics make children aware of community needs and politics. Introducing children to these activities has an impact on their future behavior. Both early and recent findings suggest that children adopt some of the political beliefs and attitudes of their parents ( Figure 6.4 ). 20 Children of Democratic parents often become registered Democrats, whereas children in Republican households often become Republicans. Children living in households where parents do not display a consistent political party loyalty are less likely to be strong Democrats or strong Republicans, and instead are often independents. 21 While family provides an informal political education, schools offer a more formal and increasingly important one. The early introduction is often broad and thematic, covering explorers, presidents, victories, and symbols, but generally the lessons are idealized and do not discuss many of the specific problems or controversies connected with historical figures and moments. George Washington ’s contributions as our first president are highlighted, for instance, but teachers are unlikely to mention that he owned slaves. Lessons will also try to personalize government and make leaders relatable to children. A teacher might discuss Abraham Lincoln ’s childhood struggle to get an education despite the death of his mother and his family’s poverty. Children learn to respect government, follow laws, and obey the requests of police, firefighters, and other first responders. The Pledge of Allegiance becomes a regular part of the school day, as students learn to show respect to our country’s symbols such as the flag and to abstractions such as liberty and equality. As students progress to higher grades, lessons will cover more detailed information about the history of the United States, its economic system, and the workings of the government. Complex topics such as the legislative process, checks and balances, and domestic policymaking are covered. Introductory economics classes teach about the various ways to build an economy, explaining how the capitalist system works. Many high schools have implemented civic volunteerism requirements as a way to encourage students to participate in their communities. Many offer Advanced Placement classes in U.S. government and history, or other honors-level courses, such as International Baccalaureate or dual-credit courses. These courses can introduce detail and realism, raise controversial topics, and encourage students to make comparisons and think critically about the United States in a global and historical context. College students may choose to pursue their academic study of the U.S. political system further, become active in campus advocacy or rights groups, or run for any of a number of elected positions on campus or even in the local community. Each step of the educational system’s socialization process will ready students to make decisions and be participating members of political society. We are also socialized outside our homes and schools. When citizens attend religious ceremonies, as 70 percent of Americans in a recent survey claimed, 22 they are socialized to adopt beliefs that affect their politics. Religion leaders often teach on matters of life, death, punishment, and obligation, which translate into views on political issues such as abortion, euthanasia, the death penalty, and military involvement abroad. Political candidates speak at religious centers and institutions in an effort to meet like-minded voters. For example, Senator Ted Cruz (R-TX) announced his 2016 presidential bid at Liberty University, a fundamentalist Christian institution. This university matched Cruz’s conservative and religious ideological leanings and was intended to give him a boost from the faith-based community. Friends and peers too have a socializing effect on citizens. Communication networks are based on trust and common interests, so when we receive information from friends and neighbors, we often readily accept it because we trust them. 23 Information transmitted through social media like Facebook is also likely to have a socializing effect. Friends “like” articles and information, sharing their political beliefs and information with one another. Media—newspapers, television, radio, and the Internet—also socialize citizens through the information they provide. For a long time, the media served as gatekeepers of our information, creating reality by choosing what to present. If the media did not cover an issue or event, it was as if it did not exist. With the rise of the Internet and social media, however, traditional media have become less powerful agents of this kind of socialization. Another way the media socializes audiences is through framing, or choosing the way information is presented. Framing can affect the way an event or story is perceived. Candidates described with negative adjectives, for instance, may do poorly on Election Day. Consider the recent demonstrations over the deaths of Michael Brown in Ferguson, Missouri, and of Freddie Gray in Baltimore, Maryland. Both deaths were caused by police actions against unarmed African American men. Brown was shot to death by an officer on August 9, 2014. Gray died from spinal injuries sustained in transport to jail in April 2015. Following each death, family, friends, and sympathizers protested the police actions as excessive and unfair. While some television stations framed the demonstrations as riots and looting, other stations framed them as protests and fights against corruption. The demonstrations contained both riot and protest, but individuals’ perceptions were affected by the framing chosen by their preferred information sources ( Figure 6.5 ). 24 Finally, media information presented as fact can contain covert or overt political material. Covert content is political information provided under the pretense that it is neutral. A magazine might run a story on climate change by interviewing representatives of only one side of the policy debate and downplaying the opposing view, all without acknowledging the one-sided nature of its coverage. In contrast, when the writer or publication makes clear to the reader or viewer that the information offers only one side of the political debate, the political message is overt content . Political commentators like Rush Limbaugh and publications like Mother Jones openly state their ideological viewpoints. While such overt political content may be offensive or annoying to a reader or viewer, all are offered the choice whether to be exposed to the material. SOCIALIZATION AND IDEOLOGY The socialization process leaves citizens with attitudes and beliefs that create a personal ideology. Ideologies depend on attitudes and beliefs, and on the way we prioritize each belief over the others. Most citizens hold a great number of beliefs and attitudes about government action. Many think government should provide for the common defense, in the form of a national military. They also argue that government should provide services to its citizens in the form of free education, unemployment benefits, and assistance for the poor. When asked how to divide the national budget, Americans reveal priorities that divide public opinion. Should we have a smaller military and larger social benefits, or a larger military budget and limited social benefits? This is the guns versus butter debate, which assumes that governments have a finite amount of money and must choose whether to spend a larger part on the military or on social programs. The choice forces citizens into two opposing groups. Divisions like these appear throughout public opinion. Assume we have four different people named Garcia, Chin, Smith, and Dupree. Garcia may believe that the United States should provide a free education for every citizen all the way through college, whereas Chin may believe education should be free only through high school. Smith might believe children should be covered by health insurance at the government’s expense, whereas Dupree believes all citizens should be covered. In the end, the way we prioritize our beliefs and what we decide is most important to us determines whether we are on the liberal or conservative end of the political spectrum, or somewhere in between. Get Connected! Express Yourself You can volunteer to participate in public opinion surveys. Diverse respondents are needed across a variety of topics to give a reliable picture of what Americans think about politics, entertainment, marketing, and more. One polling group, Harris Interactive, maintains an Internet pool of potential respondents of varied ages, education levels, backgrounds, cultures, and more. When a survey is designed and put out into the field, Harris emails an invitation to the pool to find respondents. Respondents choose which surveys to complete based on the topics, time required, and compensation offered (usually small). Harris Interactive is a subsidiary of Nielsen, a company with a long history of measuring television and media viewership in the United States and abroad. Nielsen ratings help television stations identify shows and newscasts with enough viewers to warrant being kept in production, and also to set advertising rates (based on audience size) for commercials on popular shows. Harris Interactive has expanded Nielsen’s survey methods by using polling data and interviews to better predict future political and market trends. Harris polls cover the economy, lifestyles, sports, international affairs, and more. Which topic has the most surveys? Politics, of course. Wondering what types of surveys you might get? The results of some of the surveys will give you an idea. They are available to the public on the Harris website. For more information, log in to Harris Poll Online . IDEOLOGIES AND THE IDEOLOGICAL SPECTRUM One useful way to look at ideologies is to place them on a spectrum that visually compares them based on what they prioritize. Liberal ideologies are traditionally put on the left and conservative ideologies on the right. (This placement dates from the French Revolution and is why liberals are called left-wing and conservatives are called right-wing.) The ideologies at the ends of the spectrum are the most extreme; those in the middle are moderate. Thus, people who identify with left- and right-wing ideologies identify with beliefs to the left and right ends of the spectrum, while moderates balance the beliefs at the extremes of the spectrum. In the United States, ideologies at the right side of the spectrum prioritize government control over personal freedoms. They range from fascism to authoritarianism to conservatism. Ideologies on the left side of the spectrum prioritize equality and range from communism to socialism to liberalism ( Figure 6.6 ). Moderate ideologies fall in the middle and try to balance the two extremes. Fascism promotes total control of the country by the ruling party or political leader. This form of government will run the economy, the military, society, and culture, and often tries to control the private lives of its citizens. Authoritarian leaders control the politics, military, and government of a country, and often the economy as well. Conservative governments attempt to hold tight to the traditions of a nation by balancing individual rights with the good of the community. Traditional conservatism supports the authority of the monarchy and the church, believing government provides the rule of law and maintains a society that is safe and organized. Modern conservatism differs from traditional conservatism in assuming elected government will guard individual liberties and provide laws. Modern conservatives also prefer a smaller government that stays out of the economy, allowing the market and business to determine prices, wages, and supply. Classical liberalism believes in individual liberties and rights. It is based on the idea of free will, that people are born equal with the right to make decisions without government intervention. It views government with suspicion, since history includes many examples of monarchs and leaders who limited citizens’ rights. Today, modern liberalism focuses on equality and supports government intervention in society and the economy if it promotes equality. Liberals expect government to provide basic social and educational programs to help everyone have a chance to succeed. Under socialism , the government uses its authority to promote social and economic equality within the country. Socialists believe government should provide everyone with expanded services and public programs, such as health care, subsidized housing and groceries, childhood education, and inexpensive college tuition. Socialism sees the government as a way to ensure all citizens receive both equal opportunities and equal outcomes. Citizens with more wealth are expected to contribute more to the state’s revenue through higher taxes that pay for services provided to all. Socialist countries are also likely to have higher minimum wages than non-socialist countries. In theory, communism promotes common ownership of all property, means of production, and materials. This means that the government, or states, should own the property, farms, manufacturing, and businesses. By controlling these aspects of the economy, Communist governments can prevent the exploitation of workers while creating an equal society. Extreme inequality of income, in which some citizens earn millions of dollars a year and other citizens merely hundreds, is prevented by instituting wage controls or by abandoning currency altogether. Communism presents a problem, however, because the practice differs from the theory. The theory assumes the move to communism is supported and led by the proletariat, or the workers and citizens of a country. 25 Human rights violations by governments of actual Communist countries make it appear the movement has been driven not by the people, but by leadership. We can characterize economic variations on these ideologies by adding another dimension to the ideological spectrum above—whether we prefer that government control the state economy or stay out of it. The extremes are a command economy, such as existed in the former Soviet Russia, and a laissez-faire (“leave it alone”) economy, such as in the United States prior to the 1929 market crash, when banks and corporations were largely unregulated. Communism prioritizes control of both politics and economy, while libertarianism is its near-opposite. Libertarians believe in individual rights and limited government intervention in private life and personal economic decisions. Government exists to maintain freedom and life, so its main function is to ensure domestic peace and national defense. Libertarians also believe the national government should maintain a military in case of international threats, but that it should not engage in setting minimum wages or ruling in private matters, like same-sex marriage or the right to abortion. 26 The point where a person’s ideology falls on the spectrum gives us some insight to his or her opinions. Though people can sometimes be liberal on one issue and conservative on another, a citizen to the left of liberalism, near socialism, would likely be happy with the passage of the Raise the Wage Act of 2015, which would eventually increase the minimum wage from $7.25 to $12 an hour. A citizen falling near conservatism would believe the Patriot Act is reasonable, because it allows the FBI and other government agencies to collect data on citizens’ phone calls and social media communications to monitor potential terrorism ( Figure 6.7 ). A citizen to the right of the spectrum is more likely to favor cutting social services like unemployment and Medicaid. Link to Learning Where do your beliefs come from? The Pew Research Center offers a typology quiz to help you find out. Ask a friend or family member to answer a few questions with you and compare results. What do you think about government regulation? The military? The economy? Now compare your results. Are you both liberal? Conservative? Moderate? 6.2 How Is Public Opinion Measured? Learning Objectives By the end of this section, you will be able to: Explain how information about public opinion is gathered Identify common ways to measure and quantify public opinion Analyze polls to determine whether they accurately measure a population’s opinions Polling has changed over the years. The first opinion poll was taken in 1824; it asked voters how they voted as they left their polling places. Informal polls are called straw poll s , and they informally collect opinions of a non-random population or group. Newspapers and social media continue the tradition of unofficial polls, mainly because interested readers want to know how elections will end. Facebook and online newspapers often offer informal, pop-up quizzes that ask a single question about politics or an event. The poll is not meant to be formal, but it provides a general idea of what the readership thinks. Modern public opinion polling is relatively new, only eighty years old. These polls are far more sophisticated than straw polls and are carefully designed to probe what we think, want, and value. The information they gather may be relayed to politicians or newspapers, and is analyzed by statisticians and social scientists. As the media and politicians pay more attention to the polls, an increasing number are put in the field every week. TAKING A POLL Most public opinion polls aim to be accurate, but this is not an easy task. Political polling is a science. From design to implementation, polls are complex and require careful planning and care. Mitt Romney ’s campaign polls are only a recent example of problems stemming from polling methods. Our history is littered with examples of polling companies producing results that incorrectly predicted public opinion due to poor survey design or bad polling methods. In 1936, Literary Digest continued its tradition of polling citizens to determine who would win the presidential election. The magazine sent opinion cards to people who had a subscription, a phone, or a car registration. Only some of the recipients sent back their cards. The result? Alf Landon was predicted to win 55.4 percent of the popular vote; in the end, he received only 38 percent. 27 Franklin D. Roosevelt won another term, but the story demonstrates the need to be scientific in conducting polls. A few years later, Thomas Dewey lost the 1948 presidential election to Harry Truman , despite polls showing Dewey far ahead and Truman destined to lose ( Figure 6.8 ). More recently, John Zogby, of Zogby Analytics, went public with his prediction that John Kerry would win the presidency against incumbent president George W. Bush in 2004, only to be proven wrong on election night. These are just a few cases, but each offers a different lesson. In 1948, pollsters did not poll up to the day of the election, relying on old numbers that did not include a late shift in voter opinion. Zogby’s polls did not represent likely voters and incorrectly predicted who would vote and for whom. These examples reinforce the need to use scientific methods when conducting polls, and to be cautious when reporting the results. Most polling companies employ statisticians and methodologists trained in conducting polls and analyzing data. A number of criteria must be met if a poll is to be completed scientifically. First, the methodologists identify the desired population, or group, of respondents they want to interview. For example, if the goal is to project who will win the presidency, citizens from across the United States should be interviewed. If we wish to understand how voters in Colorado will vote on a proposition, the population of respondents should only be Colorado residents. When surveying on elections or policy matters, many polling houses will interview only respondents who have a history of voting in previous elections, because these voters are more likely to go to the polls on Election Day. Politicians are more likely to be influenced by the opinions of proven voters than of everyday citizens. Once the desired population has been identified, the researchers will begin to build a sample that is both random and representative. A random sample consists of a limited number of people from the overall population, selected in such a way that each has an equal chance of being chosen. In the early years of polling, telephone numbers of potential respondents were arbitrarily selected from various areas to avoid regional bias. While landline phones allow polls to try to ensure randomness, the increasing use of cell phones makes this process difficult. Cell phones, and their numbers, are portable and move with the owner. To prevent errors, polls that include known cellular numbers may screen for zip codes and other geographic indicators to prevent regional bias. A representative sample consists of a group whose demographic distribution is similar to that of the overall population. For example, nearly 51 percent of the U.S. population is female. 28 To match this demographic distribution of women, any poll intended to measure what most Americans think about an issue should survey a sample containing slightly more women than men. Pollsters try to interview a set number of citizens to create a reasonable sample of the population. This sample size will vary based on the size of the population being interviewed and the level of accuracy the pollster wishes to reach. If the poll is trying to reveal the opinion of a state or group, such as the opinion of Wisconsin voters about changes to the education system, the sample size may vary from five hundred to one thousand respondents and produce results with relatively low error. For a poll to predict what Americans think nationally, such as about the White House’s policy on greenhouse gases, the sample size should be larger. The sample size varies with each organization and institution due to the way the data are processed. Gallup often interviews only five hundred respondents, while Rasmussen Reports and Pew Research often interview one thousand to fifteen hundred respondents. 29 Academic organizations, like the American National Election Studies, have interviews with over twenty-five-hundred respondents. 30 A larger sample makes a poll more accurate, because it will have relatively fewer unusual responses and be more representative of the actual population. Pollsters do not interview more respondents than necessary, however. Increasing the number of respondents will increase the accuracy of the poll, but once the poll has enough respondents to be representative, increases in accuracy become minor and are not cost-effective. 31 When the sample represents the actual population, the poll’s accuracy will be reflected in a lower margin of error. The margin of error is a number that states how far the poll results may be from the actual opinion of the total population of citizens. The lower the margin of error, the more predictive the poll. Large margins of error are problematic. For example, if a poll that claims Hillary Clinton is likely to win 30 percent of the vote in the 2016 New York Democratic primary has a margin of error of +/-6, it tells us that Clinton may receive as little as 24 percent of the vote (30 – 6) or as much as 36 percent (30 + 6). A lower of margin of error is clearly desirable because it gives us the most precise picture of what people actually think or will do. With many polls out there, how do you know whether a poll is a good poll and accurately predicts what a group believes? First, look for the numbers. Polling companies include the margin of error, polling dates, number of respondents, and population sampled to show their scientific reliability. Was the poll recently taken? Is the question clear and unbiased? Was the number of respondents high enough to predict the population? Is the margin of error small? It is worth looking for this valuable information when you interpret poll results. While most polling agencies strive to create quality polls, other organizations want fast results and may prioritize immediate numbers over random and representative samples. For example, instant polling is often used by news networks to quickly assess how well candidates are performing in a debate. Insider Perspective The Ins and Outs of Polls Ever wonder what happens behind the polls? To find out, we posed a few questions to Scott Keeter, Director of Survey Research at Pew Research Center. Q: What are some of the most common misconceptions about polling? A: A couple of them recur frequently. The first is that it is just impossible for one thousand or fifteen hundred people in a survey sample to adequately represent a population of 250 million adults. But of course it is possible. Random sampling, which has been well understood for the past several decades, makes it possible. If you don’t trust small random samples, then ask your doctor to take all of your blood the next time you need a diagnostic test. The second misconception is that it is possible to get any result we want from a poll if we are willing to manipulate the wording sufficiently. While it is true that question wording can influence responses, it is not true that a poll can get any result it sets out to get. People aren’t stupid. They can tell if a question is highly biased and they won’t react well to it. Perhaps more important, the public can read the questions and know whether they are being loaded with words and phrases intended to push a respondent in a particular direction. That’s why it’s important to always look at the wording and the sequencing of questions in any poll. Q: How does your organization choose polling topics? A: We choose our topics in several ways. Most importantly, we keep up with developments in politics and public policy, and try to make our polls reflect relevant issues. Much of our research is driven by the news cycle and topics that we see arising in the near future. We also have a number of projects that we do regularly to provide a look at long-term trends in public opinion. For example, we’ve been asking a series of questions about political values since 1987, which has helped to document the rise of political polarization in the public. Another is a large (thirty-five thousand interviews) study of religious beliefs, behaviors, and affiliations among Americans. We released the first of these in 2007, and a second in 2015. Finally, we try to seize opportunities to make larger contributions on weighty issues when they arise. When the United States was on the verge of a big debate on immigration reform in 2006, we undertook a major survey of Americans’ attitudes about immigration and immigrants. In 2007, we conducted the first-ever nationally representative survey of Muslim Americans. Q: What is the average number of polls you oversee in a week? A: It depends a lot on the news cycle and the needs of our research groups. We almost always have a survey in progress, but sometimes there are two or three going on at once. At other times, we are more focused on analyzing data already collected or planning for future surveys. Q: Have you placed a poll in the field and had results that really surprised you? A: It’s rare to be surprised because we’ve learned a lot over the years about how people respond to questions. But here are some findings that jumped out to some of us in the past: 1) In 2012, we conducted a survey of people who said their religion is “nothing in particular.” We asked them if they are “looking for a religion that would be right” for them, based on the expectation that many people without an affiliation—but who had not said they were atheists or agnostic—might be trying to find a religion that fit. Only 10 percent said that they were looking for the right religion. 2) We—and many others—were surprised that public opinion about Muslims became more favorable after the 9/11 terrorist attacks. It’s possible that President Bush’s strong appeal to people not to blame Muslims in general for the attack had an effect on opinions. 3) It’s also surprising that basic public attitudes about gun control (whether pro or anti) barely move after highly publicized mass shootings. Were you surprised by the results Scott Keeter reported in response to the interviewer’s final question? Why or why not? Conduct some research online to discover what degree plans or work experience would help a student find a job in a polling organization. TECHNOLOGY AND POLLING The days of randomly walking neighborhoods and phone book cold-calling to interview random citizens are gone. Scientific polling has made interviewing more deliberate. Historically, many polls were conducted in person, yet this was expensive and yielded problematic results. In some situations and countries, face-to-face interviewing still exists. Exit polls, focus groups, and some public opinion polls occur in which the interviewer and respondents communicate in person ( Figure 6.9 ). Exit polls are conducted in person, with an interviewer standing near a polling location and requesting information as voters leave the polls. Focus groups often select random respondents from local shopping places or pre-select respondents from Internet or phone surveys. The respondents show up to observe or discuss topics and are then surveyed. When organizations like Gallup or Roper decide to conduct face-to-face public opinion polls, however, it is a time-consuming and expensive process. The organization must randomly select households or polling locations within neighborhoods, making sure there is a representative household or location in each neighborhood. 32 Then it must survey a representative number of neighborhoods from within a city. At a polling location, interviewers may have directions on how to randomly select voters of varied demographics. If the interviewer is looking to interview a person in a home, multiple attempts are made to reach a respondent if he or she does not answer. Gallup conducts face-to-face interviews in areas where less than 80 percent of the households in an area have phones, because it gives a more representative sample. 33 News networks use face-to-face techniques to conduct exit polls on Election Day. Most polling now occurs over the phone or through the Internet. Some companies, like Harris Interactive, maintain directories that include registered voters, consumers, or previously interviewed respondents. If pollsters need to interview a particular population, such as political party members or retirees of a specific pension fund, the company may purchase or access a list of phone numbers for that group. Other organizations, like Gallup, use random-digit-dialing (RDD), in which a computer randomly generates phone numbers with desired area codes. Using RDD allows the pollsters to include respondents who may have unlisted and cellular numbers. 34 Questions about ZIP code or demographics may be asked early in the poll to allow the pollsters to determine which interviews to continue and which to end early. The interviewing process is also partly computerized. Many polls are now administered through computer-assisted telephone interviewing (CATI) or through robo-polls. A CATI system calls random telephone numbers until it reaches a live person and then connects the potential respondent with a trained interviewer. As the respondent provides answers, the interviewer enters them directly into the computer program. These polls may have some errors if the interviewer enters an incorrect answer. The polls may also have reliability issues if the interviewer goes off the script or answers respondents’ questions. Robo-polls are entirely computerized. A computer dials random or pre-programmed numbers and a prerecorded electronic voice administers the survey. The respondent listens to the question and possible answers and then presses numbers on the phone to enter responses. Proponents argue that respondents are more honest without an interviewer. However, these polls can suffer from error if the respondent does not use the correct keypad number to answer a question or misunderstands the question. Robo-polls may also have lower response rates, because there is no live person to persuade the respondent to answer. There is also no way to prevent children from answering the survey. Lastly, the Telephone Consumer Protection Act (1991) made automated calls to cell phones illegal, which leaves a large population of potential respondents inaccessible to robo-polls. 35 The latest challenges in telephone polling come from the shift in phone usage. A growing number of citizens, especially younger citizens, use only cell phones, and their phone numbers are no longer based on geographic areas. The Millennial generation (currently aged 21–37) is also more likely to text than to answer an unknown call, so it is harder to interview this demographic group. Polling companies now must reach out to potential respondents using email and social media to ensure they have a representative group of respondents. Yet, the technology required to move to the Internet and handheld devices presents further problems. Web surveys must be designed to run on a varied number of browsers and handheld devices. Online polls cannot detect whether a person with multiple email accounts or social media profiles answers the same poll multiple times, nor can they tell when a respondent misrepresents demographics in the poll or on a social media profile used in a poll. These factors also make it more difficult to calculate response rates or achieve a representative sample. Yet, many companies are working with these difficulties, because it is necessary to reach younger demographics in order to provide accurate data. 36 PROBLEMS IN POLLING For a number of reasons, polls may not produce accurate results. Two important factors a polling company faces are timing and human nature. Unless you conduct an exit poll during an election and interviewers stand at the polling places on Election Day to ask voters how they voted, there is always the possibility the poll results will be wrong. The simplest reason is that if there is time between the poll and Election Day, a citizen might change his or her mind, lie, or choose not to vote at all. Timing is very important during elections, because surprise events can shift enough opinions to change an election result. Of course, there are many other reasons why polls, even those not time-bound by elections or events, may be inaccurate. Link to Learning Created in 2003 to survey the American public on all topics, Rasmussen Reports is a new entry in the polling business. Rasmussen also conducts exit polls for each national election. Polls begin with a list of carefully written questions. The questions need to be free of framing, meaning they should not be worded to lead respondents to a particular answer. For example, take two questions about presidential approval. Question 1 might ask, “Given the high unemployment rate, do you approve of the job President Obama is doing?” Question 2 might ask, “Do you approve of the job President Obama is doing?” Both questions want to know how respondents perceive the president’s success, but the first question sets up a frame for the respondent to believe the economy is doing poorly before answering. This is likely to make the respondent’s answer more negative. Similarly, the way we refer to an issue or concept can affect the way listeners perceive it. The phrase “estate tax” did not rally voters to protest the inheritance tax, but the phrase “death tax” sparked debate about whether taxing estates imposed a double tax on income. 37 Many polling companies try to avoid leading question s , which lead respondents to select a predetermined answer, because they want to know what people really think. Some polls, however, have a different goal. Their questions are written to guarantee a specific outcome, perhaps to help a candidate get press coverage or gain momentum. These are called push polls. In the 2016 presidential primary race, MoveOn tried to encourage Senator Elizabeth Warren (D-MA) to enter the race for the Democratic nomination ( Figure 6.10 ). Its poll used leading questions for what it termed an “informed ballot,” and, to show that Warren would do better than Hillary Clinton , it included ten positive statements about Warren before asking whether the respondent would vote for Clinton or Warren. 38 The poll results were blasted by some in the media for being fake. Sometimes lack of knowledge affects the results of a poll. Respondents may not know that much about the polling topic but are unwilling to say, “I don’t know.” For this reason, surveys may contain a quiz with questions that determine whether the respondent knows enough about the situation to answer survey questions accurately. A poll to discover whether citizens support changes to the Affordable Care Act or Medicaid might first ask who these programs serve and how they are funded. Polls about territory seizure by the Islamic State (or ISIS) or Russia’s aid to rebels in Ukraine may include a set of questions to determine whether the respondent reads or hears any international news. Respondents who cannot answer correctly may be excluded from the poll, or their answers may be separated from the others. People may also feel social pressure to answer questions in accordance with the norms of their area or peers. 39 If they are embarrassed to admit how they would vote, they may lie to the interviewer. In the 1982 governor’s race in California, Tom Bradley was far ahead in the polls, yet on Election Day he lost. This result was nicknamed the Bradley effect , on the theory that voters who answered the poll were afraid to admit they would not vote for a black man because it would appear politically incorrect and racist. In the 2016 presidential election, the level of support for Republican nominee Donald Trump may have been artificially low in the polls due to the fact that some respondents did not want to admit they were voting for Trump. In 2010, Proposition 19 , which would have legalized and taxed marijuana in California, met with a new version of the Bradley effect. Nate Silver, a political blogger, noticed that polls on the marijuana proposition were inconsistent, sometimes showing the proposition would pass and other times showing it would fail. Silver compared the polls and the way they were administered, because some polling companies used an interviewer and some used robo-calling. He then proposed that voters speaking with a live interviewer gave the socially acceptable answer that they would vote against Proposition 19, while voters interviewed by a computer felt free to be honest ( Figure 6.11 ). 40 While this theory has not been proven, it is consistent with other findings that interviewer demographics can affect respondents’ answers. African Americans, for example, may give different responses to interviewers who are white than to interviewers who are black. 41 PUSH POLLS One of the newer byproducts of polling is the creation of push poll s , which consist of political campaign information presented as polls. A respondent is called and asked a series of questions about his or her position or candidate selections. If the respondent’s answers are for the wrong candidate, the next questions will give negative information about the candidate in an effort to change the voter’s mind. In 2014, a fracking ban was placed on the ballot in a town in Texas. Fracking, which includes injecting pressurized water into drilled wells, helps energy companies collect additional gas from the earth. It is controversial, with opponents arguing it causes water pollution, sound pollution, and earthquakes. During the campaign, a number of local voters received a call that polled them on how they planned to vote on the proposed fracking ban. 42 If the respondent was unsure about or planned to vote for the ban, the questions shifted to provide negative information about the organizations proposing the ban. One question asked, “If you knew the following, would it change your vote . . . two Texas railroad commissioners, the state agency that oversees oil and gas in Texas, have raised concerns about Russia’s involvement in the anti-fracking efforts in the U.S.?” The question played upon voter fears about Russia and international instability in order to convince them to vote against the fracking ban. These techniques are not limited to issue votes; candidates have used them to attack their opponents. The hope is that voters will think the poll is legitimate and believe the negative information provided by a “neutral” source. 6.3 What Does the Public Think? Learning Objectives By the end of this section, you will be able to: Explain why Americans hold a variety of views about politics, policy issues, and political institutions Identify factors that change public opinion Compare levels of public support for the branches of government While attitudes and beliefs are slow to change, ideology can be influenced by events. A student might leave college with a liberal ideology but become more conservative as she ages. A first-year teacher may view unions with suspicion based on second-hand information but change his mind after reading newsletters and attending union meetings. These shifts may change the way citizens vote and the answers they give in polls. For this reason, political scientists often study when and why such changes in ideology happen, and how they influence our opinions about government and politicians. EXPERIENCES THAT AFFECT PUBLIC OPINION Ideological shifts are more likely to occur if a voter’s ideology is only weakly supported by his or her beliefs. Citizens can also hold beliefs or opinions that are contrary or conflicting, especially if their knowledge of an issue or candidate is limited. And having limited information makes it easier for them to abandon an opinion. Finally, citizens’ opinions will change as they grow older and separate from family. 43 Citizens use two methods to form an opinion about an issue or candidate. The first is to rely on heuristics , shortcuts or rules of thumb (cues) for decision making. Political party membership is one of the most common heuristics in voting. Many voters join a political party whose platform aligns most closely with their political beliefs, and voting for a candidate from that party simply makes sense. A Republican candidate will likely espouse conservative beliefs, such as smaller government and lower taxes, that are often more appealing to a Republican voter. Studies have shown that up to half of voters make decisions using their political party identification, or party ID, especially in races where information about candidates is scarce. 44 In non-partisan and some local elections, where candidates are not permitted to list their party identifications, voters may have to rely on a candidate’s background or job description to form a quick opinion of a candidate’s suitability. A candidate for judge may list “criminal prosecutor” as current employment, leaving the voter to determine whether a prosecutor would make a good judge. The second method is to do research, learning background information before making a decision. Candidates, parties, and campaigns put out a large array of information to sway potential voters, and the media provide wide coverage, all of which is readily available online and elsewhere. But many voters are unwilling to spend the necessary time to research and instead vote with incomplete information. 45 Gender, race, socio-economic status, and interest-group affiliation also serve as heuristics for decision making. Voters may assume female candidates have a stronger understanding about social issues relevant to women. Business owners may prefer to vote for a candidate with a college degree who has worked in business rather than a career politician. Other voters may look to see which candidate is endorsed by the National Organization of Women (NOW), because NOW’s endorsement will ensure the candidate supports abortion rights. Opinions based on heuristics rather than research are more likely to change when the cue changes. If a voter begins listening to a new source of information or moves to a new town, the influences and cues he or she meets will change. Even if the voter is diligently looking for information to make an informed decision, demographic cues matter. Age, gender, race, and socio-economic status will shape our opinions because they are a part of our everyday reality, and they become part of our barometer on whether a leader or government is performing well. A look at the 2012 presidential election shows how the opinions of different demographic groups vary ( Figure 6.12 ). For instance, 55 percent of women voted for Barack Obama and 52 percent of men voted for Mitt Romney. Age mattered as well—60 percent of voters under thirty voted for Obama, whereas 56 percent of those over sixty-five voted for Romney. Racial groups also varied in their support of the candidates. Ninety-three percent of African Americans and 71 percent of Hispanics voted for Obama instead of Romney. 46 These demographic effects are likely to be strong because of shared experiences, concerns, and ideas. Citizens who are comfortable with one another will talk more and share opinions, leading to more opportunities to influence or reinforce one another. The political culture of a state can also have an effect on ideology and opinion. In the 1960s, Daniel Elazar researched interviews, voting data, newspapers, and politicians’ speeches. He determined that states had unique cultures and that different state governments instilled different attitudes and beliefs in their citizens, creating political culture s . Some states value tradition, and their laws try to maintain longstanding beliefs. Other states believe government should help people and therefore create large bureaucracies that provide benefits to assist citizens. Some political cultures stress citizen involvement whereas others try to exclude participation by the masses. State political cultures can affect the ideology and opinions of those who live in or move to them. For example, opinions about gun ownership and rights vary from state to state. Polls show that 61 percent of all Californians, regardless of ideology or political party, stated there should be more controls on who owns guns. 47 In contrast, in Texas, support for the right to carry a weapon is high. Fifty percent of self-identified Democrats—who typically prefer more controls on guns rather than fewer—said Texans should be allowed to carry a concealed weapon if they have a permit. 48 In this case, state culture may have affected citizens’ feelings about the Second Amendment and moved them away from the expected ideological beliefs. The workplace can directly or indirectly affect opinions about policies, social issues, and political leaders by socializing employees through shared experiences. People who work in education, for example, are often surrounded by others with high levels of education. Their concerns will be specific to the education sector and different from those in other workplaces. Frequent association with colleagues can align a person’s thinking with theirs. Workplace groups such as professional organizations or unions can also influence opinions. These organizations provide members with specific information about issues important to them and lobby on their behalf in an effort to better work environments, increase pay, or enhance shared governance. They may also pressure members to vote for particular candidates or initiatives they believe will help promote the organization’s goals. For example, teachers’ unions often support the Democratic Party because it has historically supported increased funding to public schools and universities. Important political opinion leaders, or political elite s , also shape public opinion, usually by serving as short-term cues that help voters pay closer attention to a political debate and make decisions about it. Through a talk program or opinion column, the elite commentator tells people when and how to react to a current problem or issue. Millennials and members of Generation X (currently ages 38–53) long used Jon Stewart of The Daily Show and later Stephen Colbert of The Colbert Report as shortcuts to becoming informed about current events. In the same way, older generations trusted Tom Brokaw and 60 Minutes . Because an elite source can pick and choose the information and advice to provide, the door is open to covert influence if this source is not credible or honest. Voters must be able to trust the quality of the information. When elites lose credibility, they lose their audience. News agencies are aware of the relationship between citizens and elites, which is why news anchors for major networks are carefully chosen. When Brian Williams of NBC was accused of lying about his experiences in Iraq and New Orleans, he was suspended pending an investigation. Williams later admitted to several misstatements and apologized to the public, and he was removed from The Nightly News . 49 OPINIONS ABOUT POLITICS AND POLICIES What do Americans think about their political system, policies, and institutions? Public opinion has not been consistent over the years. It fluctuates based on the times and events, and on the people holding major office ( Figure 6.13 ). Sometimes a majority of the public express similar ideas, but many times not. Where, then, does the public agree and disagree? Let’s look at the two-party system, and then at opinions about public policy, economic policy, and social policy. The United States is traditionally a two-party system. Only Democrats and Republicans regularly win the presidency and, with few exceptions, seats in Congress. The majority of voters cast ballots only for Republicans and Democrats, even when third parties are represented on the ballot. Yet, citizens say they are frustrated with the current party system. Only 32 percent identify themselves as Democrats and only 23 percent as Republicans. Democratic membership has stayed relatively the same, but the Republican Party has lost about 6 percent of its membership over the last ten years, whereas the number of self-identified independents has grown from 30 percent in 2004 to 39 percent in 2014. 50 Given these numbers, it is not surprising that 58 percent of Americans say a third party is needed in U.S. politics today. 51 Some of these changes in party allegiance may be due to generational and cultural shifts. Millennials and Generation Xers are more likely to support the Democratic Party than the Republican Party. In recent polling, 51 percent of Millennials and 49 percent of Generation Xers stated they did, whereas only 35 percent and 38 percent, respectively, supported the Republican Party. Baby Boomers (currently aged 54–72) are slightly less likely than the other groups to support the Democratic Party; only 47 percent reported doing so. The Silent Generation (born in the 1920s to early 1940s) is the only cohort whose members state they support the Republican Party as a majority. 52 Another shift in politics may be coming from the increasing number of multiracial citizens with strong cultural roots. Almost 7 percent of the population now identifies as biracial or multiracial, and that percentage is likely to grow. The number of citizens identifying as both African American and white doubled between 2000 and 2010, whereas the number of citizens identifying as both Asian American and white grew by 87 percent. The Pew study found that only 37 percent of multiracial adults favored the Republican Party, while 57 percent favored the Democratic Party. 53 As the demographic composition of the United States changes and new generations become part of the voting population, public concerns and expectations will change as well. At its heart, politics is about dividing scarce resources fairly and balancing liberties and rights. Public policy often becomes messy as politicians struggle to fix problems with the nation’s limited budget while catering to numerous opinions about how best to do so. While the public often remains quiet, simply answering public opinion polls or dutifully casting their votes on Election Day, occasionally citizens weigh in more audibly by protesting or lobbying. Some policy decisions are made without public input if they preserve the way money is allocated or defer to policies already in place. But policies that directly affect personal economics, such as tax policy, may cause a public backlash, and those that affect civil liberties or closely held beliefs may cause even more public upheaval. Policies that break new ground similarly stir public opinion and introduce change that some find difficult. The acceptance of same-sex marriage, for example, pitted those who sought to preserve their religious beliefs against those who sought to be treated equally under the law. Where does the public stand on economic policy? Only 26 percent of citizens surveyed in 2015 thought the U.S. economy was in excellent or good condition, 54 yet 42 percent believed their personal financial situation was excellent to good. 55 While this seems inconsistent, it reflects the fact that we notice what is happening outside our own home. Even if a family’s personal finances are stable, members will be aware of friends and relatives who are suffering job losses or foreclosures. This information will give them a broader, more negative view of the economy beyond their own pocketbook. When asked about government spending, the public was more united in wanting policy to be fiscally responsible without raising taxes. In 2011, nearly 73 percent of interviewed citizens believed the government was creating a deficit by spending too much money on social programs like welfare and food stamps, and only 22 percent wanted to raise taxes to pay for them. 56 When polled on which programs to cut in order to balance the nation’s budget, however, respondents were less united ( Figure 6.14 ). Nearly 21 percent said to cut education spending, whereas 22 percent wanted to cut spending on health care. Only 12 percent said to cut spending on Social Security. All these programs are used by nearly everyone at some time, which makes them less controversial and less likely to actually be cut. In general, programs that benefit only some Americans or have unclear benefits cause more controversy and discussion when the economy slows. Few citizens directly benefit from welfare and business subsidies, so it is not surprising that 52 percent of respondents wanted to cut back on welfare and 57 percent wanted to cut back business subsidies. While some farm subsidies decrease the price of food items, like milk and corn, citizens may not be aware of how these subsidies affect the price of goods at the grocery store, perhaps explaining why 44 percent of respondents stated they would prefer to cut back on agricultural subsidies. 57 Social policy consists of government’s attempts to regulate public behavior in the service of a better society. To accomplish this, government must achieve the difficult task of balancing the rights and liberties of citizens. A person’s right to privacy, for example, might need to be limited if another person is in danger. But to what extent should the government intrude in the private lives of its citizens? In a recent survey, 54 percent of respondents believed the U.S. government was too involved in trying to deal with issues of morality. 58 Abortion is a social policy issue that has caused controversy for nearly a century. One segment of the population wants to protect the rights of the unborn child. Another wants to protect the bodily autonomy of women and the right to privacy between a patient and her doctor. The divide is visible in public opinion polls, where 51 percent of respondents said abortion should be legal in most cases and 43 percent said it should be illegal in most cases. The Affordable Care Act , which increased government involvement in health care, has drawn similar controversy. In a 2015 poll, 53 percent of respondents disapproved of the act, a 9-percent increase from five years before. Much of the public’s frustration comes from the act’s mandate that individuals purchase health insurance or pay a fine (in order to create a large enough pool of insured people to reduce the overall cost of coverage), which some see as an intrusion into individual decision making. 59 Laws allowing same-sex marriage raise the question whether the government should be defining marriage and regulating private relationships in defense of personal and spousal rights. Public opinion has shifted dramatically over the last twenty years. In 1996, only 27 percent of Americans felt same-sex marriage should be legal, but recent polls show support has increased to 54 percent. 60 Despite this sharp increase, a number of states had banned same-sex marriage until the Supreme Court decided, in Obergefell v. Hodges (2015), that states were obliged to give marriage licenses to couples of the same sex and to recognize out-of-state, same-sex marriages. 61 Some churches and businesses continue to argue that no one should be compelled by the government to recognize or support a marriage between members of the same sex if it conflicts with their religious beliefs. 62 Undoubtedly, the issue will continue to cause a divide in public opinion. Another area where social policy must balance rights and liberties is public safety. Regulation of gun ownership incites strong emotions, because it invokes the Second Amendment and state culture. Of those polled nationwide, 52 percent believed government should protect the right of citizens to own guns, while 46 percent felt there should be stronger controls over gun ownership. 63 These numbers change from state to state, however, because of political culture. Immigration similarly causes strife, with citizens fearing increases in crime and social spending due to large numbers of people entering the United States illegally. Yet, 72 percent of respondents did believe there should be a path to citizenship for non-documented aliens already in the country. And while the national government’s drug policy still lists marijuana as an illegal substance, 45 percent of respondents stated they would agree if the government legalized marijuana. 64 PUBLIC OPINION AND POLITICAL INSTITUTIONS Public opinion about American institutions is measured in public approval ratings rather than in questions of choice between positions or candidates. The congressional and executive branches of government are the subject of much scrutiny and discussed daily in the media. Polling companies take daily approval polls of these two branches. The Supreme Court makes the news less frequently, and approval polls are more likely after the court has released major opinions. All three branches, however, are susceptible to swings in public approval in response to their actions and to national events. Approval ratings are generally not stable for any of the three. We next look at each in turn. The president is the most visible member of the U.S. government and a lightning rod for disagreement. Presidents are often blamed for the decisions of their administrations and political parties, and are held accountable for economic and foreign policy downturns. For these reasons, they can expect their approval ratings to slowly decline over time, increasing or decreasing slightly with specific events. On average, presidents enjoy a 66 percent approval rating when starting office, but it drops to 53 percent by the end of the first term. Presidents serving a second term average a beginning approval rating of 55.5 percent, which falls to 47 percent by the end of office. President Obama’s presidency followed the same trend. He entered office with a public approval rating of 67 percent, which fell to 54 percent by the third quarter, dropped to 52 percent after his reelection, and, as of the presidential election in November 2016, was at 46 percent ( Figure 6.15 ). Events during a president’s term may spike his or her public approval ratings. George W. Bush ’s public approval rating jumped from 51 percent on September 10, 2001, to 86 percent by September 15 following the 9/11 attacks. His father, George H. W. Bush , had received a similar spike in approval ratings (from 58 to 89 percent) following the end of the first Persian Gulf War in 1991. 65 These spikes rarely last more than a few weeks, so presidents try to quickly use the political capital they bring. For example, the 9/11 rally effect helped speed a congressional joint resolution authorizing the president to use troops, and the “global war on terror” became a reality. 66 The rally was short-lived, and support for the wars in Iraq and Afghanistan quickly deteriorated post-2003. 67 Some presidents have had higher or lower public approval than others, though ratings are difficult to compare, because national and world events that affect presidential ratings are outside a president’s control. Several chief executives presided over failing economies or wars, whereas others had the benefit of strong economies and peace. Gallup, however, gives an average approval rating for each president across the entire period served in office. George W. Bush’s average approval rating from 2001 to 2008 was 49.4 percent. Ronald Reagan ’s from 1981 to 1988 was 52.8 percent, despite his winning all but thirteen electoral votes in his reelection bid. Bill Clinton ’s average approval from 1993 to 2000 was 55.1 percent, including the months surrounding the Monica Lewinsky scandal and his subsequent impeachment. To compare other notable presidents, John F. Kennedy averaged 70.1 percent and Richard Nixon 49 percent. 68 Kennedy’s average was unusually high because his time in office was short; he was assassinated before he could run for reelection, leaving less time for his ratings to decline. Nixon’s unusually low approval ratings reflect several months of media and congressional investigations into his involvement in the Watergate affair, as well as his resignation in the face of likely impeachment. Link to Learning Gallup polling has tracked approval ratings for all presidents since Harry Truman. The Presidential Job Approval Center allows you to compare weekly approval ratings for all tracked presidents, as well as their average approval ratings. Milestone Public Mood and Watershed Moments Polling is one area of U.S. politics in which political practitioners and political science scholars interact. Each election cycle, political scientists help media outlets interpret polling, statistical data, and election forecasts. One particular watershed moment in this regard occurred when Professor James Stimson, of the University of North Carolina at Chapel Hill, developed his aggregated measure of public mood. This measure takes a variety of issue positions and combines them to form a general ideology about the government. According to Professor Stimson, the American electorate became more conservative in the 1970s and again in the 1990s, as demonstrated by Republican gains in Congress. With this public mood measure in mind, political scientists can explain why and when Americans allowed major policy shifts. For example, the Great Society’s expansion of welfare and social benefits occurred during the height of liberalism in the mid-1960s, while the welfare cuts and reforms of the 1990s occurred during the nation’s move toward conservatism. Tracking conservative and liberal shifts in the public’s ideology allows policy analysts to predict whether voters are likely to accept or reject major policies. What other means of measuring the public mood do you think might be effective and reliable? How would you implement them? Do you agree that watershed moments in history signal public mood changes? If so, give some examples. If not, why not? Congress as an institution has historically received lower approval ratings than presidents, a striking result because individual senators and representatives are generally viewed favorably by their constituents. While congressional representatives almost always win reelection and are liked by their constituents back home, the institution itself is often vilified as representing everything that is wrong with politics and partisanship. As of August 2015, public approval of Congress sat at around 20 percent. 69 For most of the last forty years, congressional approval levels have bounced between 20 percent and 60 percent, but in the last fifteen years they have regularly fallen below 40 percent. Like President George W. Bush, Congress experienced a short-term jump in approval ratings immediately following 9/11, likely because of the rallying effect of the terrorist attacks. Congressional approval had dropped back below 50 percent by early 2003 ( Figure 6.16 ). While presidents are affected by foreign and domestic events, congressional approval is mainly affected by domestic events. When the economy rebounds or gas prices drop, public approval of Congress tends to go up. But when party politics within Congress becomes a domestic event, public approval falls. The passage of revenue bills has become an example of such an event, because deficits require Congress to make policy decisions before changing the budget. Deficit and debt are not new to the United States. Congress and presidents have attempted various methods of controlling debt, sometimes successfully and sometimes not. In the past three decades alone, however, several prominent examples have shown how party politics make it difficult for Congress to agree on a budget without a fight, and how these fights affect public approval. In 1995, Democratic president Bill Clinton and the Republican Congress hit a notable stalemate on the national budget. In this case, the Republicans had recently gained control of the House of Representatives and disagreed with Democrats and the president on how to cut spending and reduce the deficit. The government shut down twice, sending non-essential employees home for a few days in November, and then again in December and January. 70 Congressional approval fell during the event, from 35 to 30 percent. 71 Divisions between the political parties, inside the Republican Party, and between Congress and the president became more pronounced over the next fifteen years, with the media closely covering the political strife. 72 In 2011, the United States reached its debt ceiling, or maximum allowed debt amount. After much debate, the Budget Control Act was passed by Congress and signed by President Obama . The act increased the debt ceiling, but it also reduced spending and created automatic cuts, called sequestrations, if further legislation did not deal with the debt by 2013. When the country reached its new debt ceiling of $16.4 trillion in 2013, short-term solutions led to Congress negotiating both the debt ceiling and the national budget at the same time. The timing raised the stakes of the budget, and Democrats and Republicans fought bitterly over the debt ceiling, budget cuts, and taxes. Inaction triggered the automatic cuts to the budget in areas like defense, the courts, and public aid. By October, approximately 800,000 federal employees had been sent home, and the government went into partial shut-down for sixteen days before Congress passed a bill to raise the debt ceiling. 73 The handling of these events angered Americans, who felt the political parties needed to work together to solve problems rather than play political games. During the 2011 ceiling debate, congressional approval fell from 18 to 13 percent, while in 2013, congressional approval fell to a new low of 9 percent in November. 74 The Supreme Court generally enjoys less visibility than the other two branches of government, which leads to more stable but also less frequent polling results. Indeed, 22 percent of citizens surveyed in 2014 had never heard of Chief Justice John Roberts , the head of the Supreme Court. 75 The court is protected by the justices’ non-elected, non-political positions, which gives them the appearance of integrity and helps the Supreme Court earn higher public approval ratings than presidents and Congress. To compare, between 2000 and 2010, the court’s approval rating bounced between 50 and 60 percent. During this same period, Congress had a 20 to 40 percent approval rating. The Supreme Court’s approval rating is also less susceptible to the influence of events. Support of and opinions about the court are affected when the justices rule on highly visible cases that are of public interest or other events occur that cause citizens to become aware of the court. 76 For example, following the Bush v. Gore case (2000), in which the court instructed Florida to stop recounting ballots and George W. Bush won the Electoral College, 80 percent of Republicans approved of the court, versus only 42 percent of Democrats. 77 Twelve years later, when the Supreme Court’s ruling in National Federation of Independent Business v. Sebelius (2012) let stand the Affordable Care Act’s requirement of individual coverage, approval by Democrats increased to 68 percent, while Republican support dropped to 29 percent. 78 Currently, following the handing down of decisions in King v. Burwell (2015) and Obergefell v. Hodges (2015), which allowed the Affordable Care Act ’s subsidies and prohibited states from denying same-sex marriage, respectively, 45 percent of people said they approved of the way the Supreme Court handled its job, down 4 percent from before the decisions. 79 6.4 The Effects of Public Opinion Learning Objectives By the end of this section, you will be able to: Explain the circumstances that lead to public opinion affecting policy Compare the effects of public opinion on government branches and figures Identify situations that cause conflicts in public opinion Public opinion polling is prevalent even outside election season. Are politicians and leaders listening to these polls, or is there some other reason for them? Some believe the increased collection of public opinion is due to growing support of delegate representation. The theory of delegate representation assumes the politician is in office to be the voice of the people. 80 If voters want the legislator to vote for legalizing marijuana, for example, the legislator should vote to legalize marijuana. Legislators or candidates who believe in delegate representation may poll the public before an important vote comes up for debate in order to learn what the public desires them to do. Others believe polling has increased because politicians, like the president, operate in permanent campaign mode. To continue contributing money, supporters must remain happy and convinced the politician is listening to them. Even if the elected official does not act in a manner consistent with the polls, he or she can mollify everyone by explaining the reasons behind the vote. 81 Regardless of why the polls are taken, studies have not clearly shown whether the branches of government consistently act on them. Some branches appear to pay closer attention to public opinion than other branches, but events, time periods, and politics may change the way an individual or a branch of government ultimately reacts. PUBLIC OPINION AND ELECTIONS Elections are the events on which opinion polls have the greatest measured effect. Public opinion polls do more than show how we feel on issues or project who might win an election. The media use public opinion polls to decide which candidates are ahead of the others and therefore of interest to voters and worthy of interview. From the moment President Obama was inaugurated for his second term, speculation began about who would run in the 2016 presidential election. Within a year, potential candidates were being ranked and compared by a number of newspapers. 82 The speculation included favorability poll s on Hillary Clinton , which measured how positively voters felt about her as a candidate. The media deemed these polls important because they showed Clinton as the frontrunner for the Democrats in the next election. 83 During presidential primary season, we see examples of the bandwagon effect , in which the media pays more attention to candidates who poll well during the fall and the first few primaries. Bill Clinton was nicknamed the “Comeback Kid” in 1992, after he placed second in the New Hampshire primary despite accusations of adultery with Gennifer Flowers. The media’s attention on Clinton gave him the momentum to make it through the rest of the primary season, ultimately winning the Democratic nomination and the presidency. Link to Learning Wondering how your favorite candidate is doing in the polls? The site RealClearPolitics tracks a number of major polling sources on the major elections, including the presidential and Senate elections. Polling is also at the heart of horserace coverage , in which, just like an announcer at the racetrack, the media calls out every candidate’s move throughout the presidential campaign. Horserace coverage can be neutral, positive, or negative, depending upon what polls or facts are covered ( Figure 6.17 ). During the 2012 presidential election, the Pew Research Center found that both Mitt Romney and President Obama received more negative than positive horserace coverage, with Romney’s growing more negative as he fell in the polls. 84 Horserace coverage is often criticized for its lack of depth; the stories skip over the candidates’ issue positions, voting histories, and other facts that would help voters make an informed decision. Yet, horserace coverage is popular because the public is always interested in who will win, and it often makes up a third or more of news stories about the election. 85 Exit polls, taken the day of the election, are the last election polls conducted by the media. Announced results of these surveys can deter voters from going to the polls if they believe the election has already been decided. Finding a Middle Ground Should Exit Polls Be Banned? Exit polling seems simple. An interviewer stands at a polling place on Election Day and asks people how they voted. But the reality is different. Pollsters must select sites and voters carefully to ensure a representative and random poll. Some people refuse to talk and others may lie. The demographics of the polled population may lean more towards one party than another. Absentee and early voters cannot be polled. Despite these setbacks, exit polls are extremely interesting and controversial, because they provide early information about which candidate is ahead. In 1985, a so-called gentleman’s agreement between the major networks and Congress kept exit poll results from being announced before a state’s polls closed. 86 This tradition has largely been upheld, with most media outlets waiting until 7 p.m. or later to disclose a state’s returns. Internet and cable media, however, have not always kept to the agreement. Sources like Matt Drudge have been accused of reporting early, and sometimes incorrect, exit poll results. On one hand, delaying results may be the right decision. Studies suggest that exit polls can affect voter turnout. Reports of close races may bring additional voters to the polls, whereas apparent landslides may prompt people to stay home. Other studies note that almost anything, including bad weather and lines at polling places, dissuades voters. Ultimately, it appears exit poll reporting affects turnout by up to 5 percent. 87 On the other hand, limiting exit poll results means major media outlets lose out on the chance to share their carefully collected data, leaving small media outlets able to provide less accurate, more impressionistic results. And few states are affected anyway, since the media invest only in those where the election is close. Finally, an increasing number of voters are now voting up to two weeks early, and these numbers are updated daily without controversy. What do you think? Should exit polls be banned? Why or why not? Public opinion polls also affect how much money candidates receive in campaign donations. Donors assume public opinion polls are accurate enough to determine who the top two to three primary candidates will be, and they give money to those who do well. Candidates who poll at the bottom will have a hard time collecting donations, increasing the odds that they will continue to do poorly. This was apparent in the run-up to the 2016 presidential election. Bernie Sanders , Hillary Clinton , and Martin O’Malley each campaigned in the hope of becoming the Democratic presidential nominee. In June 2015, 75 percent of Democrats likely to vote in their state primaries said they would vote for Clinton, while 15 percent of those polled said they would vote for Sanders. Only 2 percent said they would vote for O’Malley. 88 During this same period, Clinton raised $47 million in campaign donations, Sanders raised $15 million, and O’Malley raised $2 million. 89 By September 2015, 23 percent of likely Democratic voters said they would vote for Sanders, 90 and his summer fundraising total increased accordingly. 91 Presidents running for reelection also must perform well in public opinion polls, and being in office may not provide an automatic advantage. Americans often think about both the future and the past when they decide which candidate to support. 92 They have three years of past information about the sitting president, so they can better predict what will happen if the incumbent is reelected. That makes it difficult for the president to mislead the electorate. Voters also want a future that is prosperous. Not only should the economy look good, but citizens want to know they will do well in that economy. 93 For this reason, daily public approval polls sometimes act as both a referendum of the president and a predictor of success. PUBLIC OPINION AND GOVERNMENT The relationship between public opinion polls and government action is murkier than that between polls and elections. Like the news media and campaign staffers, members of the three branches of government are aware of public opinion. But do politicians use public opinion polls to guide their decisions and actions? The short answer is “sometimes.” The public is not perfectly informed about politics, so politicians realize public opinion may not always be the right choice. Yet many political studies, from the American Voter in the 1920s to the American Voter Revisited in the 2000s, have found that voters behave rationally despite having limited information. Individual citizens do not take the time to become fully informed about all aspects of politics, yet their collective behavior and the opinions they hold as a group make sense. They appear to be informed just enough, using preferences like their political ideology and party membership, to make decisions and hold politicians accountable during an election year. Overall, the collective public opinion of a country changes over time, even if party membership or ideology does not change dramatically. As James Stimson’s prominent study found, the public’s mood, or collective opinion, can become more or less liberal from decade to decade. While the initial study on public mood revealed that the economy has a profound effect on American opinion, 94 further studies have gone beyond to determine whether public opinion, and its relative liberalness, in turn affect politicians and institutions. This idea does not argue that opinion never affects policy directly, rather that collective opinion also affects the politician’s decisions on policy. 95 Individually, of course, politicians cannot predict what will happen in the future or who will oppose them in the next few elections. They can look to see where the public is in agreement as a body. If public mood changes, the politicians may change positions to match the public mood. The more savvy politicians look carefully to recognize when shifts occur. When the public is more or less liberal, the politicians may make slight adjustments to their behavior to match. Politicians who frequently seek to win office, like House members, will pay attention to the long- and short-term changes in opinion. By doing this, they will be less likely to lose on Election Day. 96 Presidents and justices, on the other hand, present a more complex picture. Public opinion of the president is different from public opinion of Congress. Congress is an institution of 535 members, and opinion polls look at both the institution and its individual members. The president is both a person and the head of an institution. The media pays close attention to any president’s actions, and the public is generally well informed and aware of the office and its current occupant. Perhaps this is why public opinion has an inconsistent effect on presidents’ decisions. As early as Franklin D. Roosevelt ’s administration in the 1930s, presidents have regularly polled the public, and since Richard Nixon ’s term (1969–1974), they have admitted to using polling as part of the decision-making process. Presidential responsiveness to public opinion has been measured in a number of ways, each of which tells us something about the effect of opinion. One study examined whether presidents responded to public opinion by determining how often they wrote amicus briefs and asked the court to affirm or reverse cases. It found that the public’s liberal (or non-liberal) mood had an effect, causing presidents to pursue and file briefs in different cases. 97 But another author found that the public’s level of liberalness is ignored when conservative presidents, such as Ronald Reagan or George W. Bush , are elected and try to lead. In one example, our five most recent presidents’ moods varied from liberal to non-liberal, while public sentiment stayed consistently liberal. 98 While the public supported liberal approaches to policy, presidential action varied from liberal to non-liberal. Overall, it appears that presidents try to move public opinion towards personal positions rather than moving themselves towards the public’s opinion. 99 If presidents have enough public support, they use their level of public approval indirectly as a way to get their agenda passed. Immediately following Inauguration Day, for example, the president enjoys the highest level of public support for implementing campaign promises. This is especially true if the president has a mandate , which is more than half the popular vote. Barack Obama ’s recent 2008 victory was a mandate with 52.9 percent of the popular vote and 67.8 percent of the Electoral College vote. 100 In contrast, President Donald Trump’s victory over Democratic nominee Hillary Clinton was a closer contest. While Trump finished with a solid lead in the Electoral College, Clinton vastly outstripped Trump in the popular vote. When presidents have high levels of public approval, they are likely to act quickly and try to accomplish personal policy goals. They can use their position and power to focus media attention on an issue. This is sometimes referred to as the bully pulpit approach. The term “bully pulpit” was coined by President Theodore Roosevelt , who believed the presidency commanded the attention of the media and could be used to appeal directly to the people. Roosevelt used his position to convince voters to pressure Congress to pass laws. Increasing partisanship has made it more difficult for presidents to use their power to get their own preferred issues through Congress, however, especially when the president’s party is in the minority in Congress. 101 For this reason, modern presidents may find more success in using their popularity to increase media and social media attention on an issue. Even if the president is not the reason for congressional action, he or she can cause the attention that leads to change. 102 Presidents may also use their popularity to ask the people to act. In October 2015, following a shooting at Umpqua Community College in Oregon, President Obama gave a short speech from the West Wing of the White House ( Figure 6.18 ). After offering his condolences and prayers to the community, he remarked that prayers and condolences were no longer enough, and he called on citizens to push Congress for a change in gun control laws. President Obama had proposed gun control reform following the 2012 shooting at Sandy Hook Elementary in Connecticut, but it did not pass Congress. This time, the president asked citizens to use gun control as a voting issue and push for reform via the ballot box. In some instances, presidents may appear to directly consider public opinion before acting or making decisions. In 2013, President Obama announced that he was considering a military strike on Syria in reaction to the Syrian government’s illegal use of sarin gas on its own citizens. Despite agreeing that this chemical attack on the Damascan suburbs was a war crime, the public was against U.S. involvement. Forty-eight percent of respondents said they opposed airstrikes, and only 29 percent were in favor. Democrats were especially opposed to military intervention. 103 President Obama changed his mind and ultimately allowed Russian president Vladimir Putin to negotiate Syria’s surrender of its chemical weapons. However, further examples show that presidents do not consistently listen to public opinion. After taking office in 2009, President Obama did not order the closing of Guantanamo Bay prison, even though his proposal to do so had garnered support during the 2008 election. President Bush , despite growing public disapproval for the war in Iraq, did not end military support in Iraq after 2006. And President Bill Clinton , whose White House pollsters were infamous for polling on everything, sometimes ignored the public if circumstances warranted. 104 In 1995, despite public opposition, Clinton guaranteed loans for the Mexican government to help the country out of financial insolvency. He followed this decision with many speeches to help the American public understand the importance of stabilizing Mexico’s economy. Individual examples like these make it difficult to persuasively identify the direct effects of public opinion on the presidency. While presidents have at most only two terms to serve and work, members of Congress can serve as long as the public returns them to office. We might think that for this reason public opinion is important to representatives and senators, and that their behavior, such as their votes on domestic programs or funding, will change to match the expectation of the public. In a more liberal time, the public may expect to see more social programs. In a non-liberal time, the public mood may favor austerity, or decreased government spending on programs. Failure to recognize shifts in public opinion may lead to a politician’s losing the next election. 105 House of Representatives members, with a two-year term, have a more difficult time recovering from decisions that anger local voters. And because most representatives continually fundraise, unpopular decisions can hurt their campaign donations. For these reasons, it seems representatives should be susceptible to polling pressure. Yet one study, by James Stimson, found that the public mood does not directly affect elections, and shifts in public opinion do not predict whether a House member will win or lose. These elections are affected by the president on the ticket, presidential popularity (or lack thereof) during a midterm election, and the perks of incumbency, such as name recognition and media coverage. In fact, a later study confirmed that the incumbency effect is highly predictive of a win, and public opinion is not. 106 In spite of this, we still see policy shifts in Congress, often matching the policy preferences of the public. When the shifts happen within the House, they are measured by the way members vote. The study’s authors hypothesize that House members alter their votes to match the public mood, perhaps in an effort to strengthen their electoral chances. 107 The Senate is quite different from the House. Senators do not enjoy the same benefits of incumbency, and they win reelection at lower rates than House members. Yet, they do have one advantage over their colleagues in the House: Senators hold six-year terms, which gives them time to engage in fence-mending to repair the damage from unpopular decisions. In the Senate, Stimson’s study confirmed that opinion affects a senator’s chances at reelection, even though it did not affect House members. Specifically, the study shows that when public opinion shifts, fewer senators win reelection. Thus, when the public as a whole becomes more or less liberal, new senators are elected. Rather than the senators shifting their policy preferences and voting differently, it is the new senators who change the policy direction of the Senate. 108 Beyond voter polls, congressional representatives are also very interested in polls that reveal the wishes of interest groups and businesses. If AARP , one of the largest and most active groups of voters in the United States, is unhappy with a bill, members of the relevant congressional committees will take that response into consideration. If the pharmaceutical or oil industry is unhappy with a new patent or tax policy, its members’ opinions will have some effect on representatives’ decisions, since these industries contribute heavily to election campaigns. Link to Learning The website of the Policy Agendas Project details a National Science Foundation-funded policy project to provide data on public opinion, presidential public approval, and a variety of governmental measures of activity. All data are coded by policy topic, so you can look for trends in a policy topic of interest to you to see whether government attention tracks with public opinion. There is some disagreement about whether the Supreme Court follows public opinion or shapes it. The lifetime tenure the justices enjoy was designed to remove everyday politics from their decisions, protect them from swings in political partisanship, and allow them to choose whether and when to listen to public opinion. More often than not, the public is unaware of the Supreme Court’s decisions and opinions. When the justices accept controversial cases, the media tune in and ask questions, raising public awareness and affecting opinion. But do the justices pay attention to the polls when they make decisions? Studies that look at the connection between the Supreme Court and public opinion are contradictory. Early on, it was believed that justices were like other citizens: individuals with attitudes and beliefs who would be affected by political shifts. 109 Later studies argued that Supreme Court justices rule in ways that maintain support for the institution. Instead of looking at the short term and making decisions day to day, justices are strategic in their planning and make decisions for the long term. 110 Other studies have revealed a more complex relationship between public opinion and judicial decisions, largely due to the difficulty of measuring where the effect can be seen. Some studies look at the number of reversals taken by the Supreme Court, which are decisions with which the Court overturns the decision of a lower court. In one study, the authors found that public opinion slightly affects cases accepted by the justices. 111 In a study looking at how often the justices voted liberally on a decision, a stronger effect of public opinion was revealed. 112 Whether the case or court is currently in the news may also matter. A study found that if the majority of Americans agree on a policy or issue before the court, the court’s decision is likely to agree with public opinion. 113 A second study determined that public opinion is more likely to affect ignored cases than heavily reported ones. 114 In these situations, the court was also more likely to rule with the majority opinion than against it. For example, in Town of Greece v. Galloway (2014), a majority of the justices decided that ceremonial prayer before a town meeting was not a violation of the Establishment Clause. 115 The fact that 78 percent of U.S. adults recently said religion is fairly to very important to their lives 116 and 61 percent supported prayer in school 117 may explain why public support for the Supreme Court did not fall after this decision. 118 Overall, however, it is clear that public opinion has a less powerful effect on the courts than on the other branches and on politicians. 119 Perhaps this is due to the lack of elections or justices’ lifetime tenure, or perhaps we have not determined the best way to measure the effects of public opinion on the Court.
principles_of_accounting,_volume_1:_financial_accounting
Summary 16.1 Explain the Purpose of the Statement of Cash Flows The statement of cash flows presents the sources and uses of cash. The statement of cash flows is used to predict future cash flows and to assess the quality of an entity’s earnings. There are two approaches utilized to prepare the statement of cash flow: the indirect method and the direct method. 16.2 Differentiate between Operating, Investing, and Financing Activities Transactions must be segregated into the three types of activities presented on the statement of cash flows: operating, investing, and financing. Operating cash flows arise from the normal operations of producing income, such as cash receipts from revenue and cash disbursements to pay for expenses. Investing cash flows arise from a company investing in or disposing of long-term assets. Financing cash flows arise from a company raising funds through debt or equity and repaying debt. 16.3 Prepare the Statement of Cash Flows Using the Indirect Method Preparing the operating section of statement of cash flows by the indirect method starts with net income from the income statement and adjusts for items that affect cash flows differently than they affect net income. Multiple levels of adjustments are required to reconcile accrual-based net income to cash flows from operating activities. The investing section of statement of cash flows relates to changes in long-term assets. The financing section of statement of cash flows relates to changes in long-term liabilities and changes in equity. Company activities that reflect changes in long-term assets, long-term liabilities, or equity, but have no cash impact, require special reporting treatment, as noncash investing and financing transactions. 16.4 Prepare the Completed Statement of Cash Flows Using the Indirect Method Preparing the operating section of statement of cash flows by the indirect method starts with net income from the income statement and adjusts for items that affect cash flows differently than they affect net income. Multiple levels of adjustments are required to reconcile accrual-based net income to cash flows from operating activities. The investing section of the statement of cash flows relates to changes in long-term assets. The financing section of statement of cash flows relates to changes in long-term liabilities and changes in equity. Company activities that reflect changes in long-term assets, long-term liabilities, or equity, but have no cash impact, require special reporting treatment, as noncash investing and financing transactions. 16.5 Use Information from the Statement of Cash Flows to Prepare Ratios to Assess Liquidity and Solvency Free cash flow relates to the amount of expected cash from operations which is left over after planned capital expenditures and dividends are paid. The cash flow to assets ratio correlates the company’s free cash flow to its total asset value. The cash flow to sales ratio considers free cash flow in relation to the company’s sales revenue. 16.6 Appendix: Prepare a Completed Statement of Cash Flows Using the Direct Method This section included an example of a statement of cash flows, prepared under the direct method, using the continuing example for Propensity Company. The direct method of preparing the statement of cash flows is identical to the indirect method except for the cash flows from the operating section. To complete the cash flows from operating activities, the direct method directly shows the cash collected from customers from revenue activities and the cash spent on operations, rather than reconciling net income to cash flows from operating activities as done using the indirect method. Calculating the amounts directly collected from revenues and spent on expenditures involves calculating the cash effect of the accrual amounts reported on the income statement.
Chapter Outline 16.1 Explain the Purpose of the Statement of Cash Flows 16.2 Differentiate between Operating, Investing, and Financing Activities 16.3 Prepare the Statement of Cash Flows Using the Indirect Method 16.4 Prepare the Completed Statement of Cash Flows Using the Indirect Method 16.5 Use Information from the Statement of Cash Flows to Prepare Ratios to Assess Liquidity and Solvency 16.6 Appendix: Prepare a Completed Statement of Cash Flows Using the Direct Method Why It Matters Most financial accounting processes focus on the accrual basis of accounting, which reflects revenue earned, regardless of whether that revenue has been collected or not, and the related costs involved in producing that revenue, whether those costs have been paid or not. Yet the single-minded focus on accrued revenues and expenses, without consideration of the cash impact of these transactions, can jeopardize the ability of users of the financial statements to make well-informed decisions. Some investors say that “cash is king,” meaning that they think a company’s cash flow is more important than its net income in determining investment opportunities. Companies go bankrupt because they run out of cash. Financial statement users should be able to develop a picture of how well a company’s net income generates cash and the sources and uses of a company’s cash. From the statement of cash flows, it becomes possible to reconcile income on the income statement to the cash actually generated during the same period. Having cash alone is not important, but the source and use of cash are also important, specifically where the cash is coming from. If the business is generating cash from operations (selling products and services), that is positive. If the company only has cash as it is taking out loans and selling assets, one must be careful in their analysis.
[ { "answer": { "ans_choice": 2, "ans_text": "C" }, "bloom": null, "hl_context": "<hl> Gains and / or losses on the disposal of long-term assets are included in the calculation of net income , but cash obtained from disposing of long-term assets is a cash flow from an investing activity . <hl> <hl> Because the disposition gain or loss is not related to normal operations , the adjustment needed to arrive at cash flow from operating activities is a reversal of any gains or losses that are included in the net income total . <hl> A gain is subtracted from net income and a loss is added to net income to reconcile to cash from operating activities . Propensity ’ s income statement for the year 2018 includes a gain on sale of land , in the amount of $ 4,800 , so a reversal is accomplished by subtracting the gain from net income . On Propensity ’ s statement of cash flows , this amount is shown in the Cash Flows from Operating Activities section as Gain on Sale of Plant Assets . <hl> Net income includes deductions for noncash expenses . <hl> <hl> To reconcile net income to cash flow from operating activities , these noncash items must be added back , because no cash was expended relating to that expense . <hl> The sole noncash expense on Propensity Company ’ s income statement , which must be added back , is the depreciation expense of $ 14,400 . On Propensity ’ s statement of cash flows , this amount is shown in the Cash Flows from Operating Activities section as an adjustment to reconcile net income to net cash flow from operating activities .", "hl_sentences": "Gains and / or losses on the disposal of long-term assets are included in the calculation of net income , but cash obtained from disposing of long-term assets is a cash flow from an investing activity . Because the disposition gain or loss is not related to normal operations , the adjustment needed to arrive at cash flow from operating activities is a reversal of any gains or losses that are included in the net income total . Net income includes deductions for noncash expenses . To reconcile net income to cash flow from operating activities , these noncash items must be added back , because no cash was expended relating to that expense .", "question": { "cloze_format": "A false statement is that ___ .", "normal_format": "Which of the following statements is false?", "question_choices": [ "Noncash activities should be reported in accrual basis financial statements.", "Net cash flow from operating activities relates to normal business operations.", "Net income usually equals net cash flow from operating activities.", "The statement of cash flows is an essential part of the basic financial statements." ], "question_id": "fs-idm255327648", "question_text": "Which of the following statements is false?" }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 2, "ans_text": "cash paid for purchase of equipment" }, "bloom": null, "hl_context": "Cash flows from operating activities arise from the activities a business uses to produce net income . <hl> For example , operating cash flows include cash sources from sales and cash used to purchase inventory and to pay for operating expenses such as salaries and utilities . <hl> Operating cash flows also include cash flows from interest and dividend revenue interest expense , and income tax .", "hl_sentences": "For example , operating cash flows include cash sources from sales and cash used to purchase inventory and to pay for operating expenses such as salaries and utilities .", "question": { "cloze_format": "The transaction that would not be part of the cash flows from the operating activities section of the statement of cash flows is the ___ .", "normal_format": "Which of these transactions would not be part of the cash flows from the operating activities section of the statement of cash flows?", "question_choices": [ "credit purchase of inventory", "sales of product, for cash", "cash paid for purchase of equipment", "salary payments to employees" ], "question_id": "fs-idm259261696", "question_text": "Which of these transactions would not be part of the cash flows from the operating activities section of the statement of cash flows?" }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 1, "ans_text": "B" }, "bloom": null, "hl_context": "<hl> The statement of cash flows presents sources and uses of cash in three distinct categories : cash flows from operating activities , cash flows from investing activities , and cash flows from financing activities . <hl> Financial statement users are able to assess a company ’ s strategy and ability to generate a profit and stay in business by assessing how much a company relies on operating , investing , and financing activities to produce its cash flows .", "hl_sentences": "The statement of cash flows presents sources and uses of cash in three distinct categories : cash flows from operating activities , cash flows from investing activities , and cash flows from financing activities .", "question": { "cloze_format": "The proper order of the sections of the statement of cash flows is ___ .", "normal_format": "Which is the proper order of the sections of the statement of cash flows?", "question_choices": [ "financing, investing, operating", "operating, investing, financing", "investing, operating, financing", "operating, financing, investing" ], "question_id": "fs-idm256771088", "question_text": "Which is the proper order of the sections of the statement of cash flows?" }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 3, "ans_text": "dividend payments to shareholders, paid in cash" }, "bloom": null, "hl_context": "<hl> Cash flows from financing activities always relate to either long-term debt or equity transactions and may involve increases or decreases in cash relating to these transactions . <hl> <hl> Stockholders ’ equity transactions , like stock issuance , dividend payments , and treasury stock buybacks are very common financing activities . <hl> Debt transactions , such as issuance of bonds payable or notes payable , and the related principal payback of them , are also frequent financing events . Changes in long-term liabilities and equity for the period can be identified in the Noncurrent Liabilities section and the Stockholders ’ Equity section of the company ’ s Comparative Balance Sheet , and in the retained earnings statement . Think It Through Classification of Cash Flows Makes a Difference Assume you are the chief financial officer of T-Shirt Pros , a small business that makes custom-printed T-shirts . While reviewing the financial statements that were prepared by company accountants , you discover an error . During this period , the company had purchased a warehouse building , in exchange for a $ 200,000 note payable . The company ’ s policy is to report noncash investing and financing activities in a separate statement , after the presentation of the statement of cash flows . <hl> This noncash investing and financing transaction was inadvertently included in both the financing section as a source of cash , and the investing section as a use of cash . <hl>", "hl_sentences": "Cash flows from financing activities always relate to either long-term debt or equity transactions and may involve increases or decreases in cash relating to these transactions . Stockholders ’ equity transactions , like stock issuance , dividend payments , and treasury stock buybacks are very common financing activities . This noncash investing and financing transaction was inadvertently included in both the financing section as a source of cash , and the investing section as a use of cash .", "question": { "cloze_format": "The transaction that would be part of the financing section is called the ___ .", "normal_format": "Which of these transactions would be part of the financing section?", "question_choices": [ "inventory purchased for cash", "sales of product, for cash", "cash paid for purchase of equipment", "dividend payments to shareholders, paid in cash" ], "question_id": "fs-idm266570880", "question_text": "Which of these transactions would be part of the financing section?" }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 1, "ans_text": "B" }, "bloom": null, "hl_context": "<hl> Cash flows from operating activities arise from the activities a business uses to produce net income . <hl> <hl> For example , operating cash flows include cash sources from sales and cash used to purchase inventory and to pay for operating expenses such as salaries and utilities . <hl> Operating cash flows also include cash flows from interest and dividend revenue interest expense , and income tax . Most financial accounting processes focus on the accrual basis of accounting , which reflects revenue earned , regardless of whether that revenue has been collected or not , and the related costs involved in producing that revenue , whether those costs have been paid or not . Yet the single-minded focus on accrued revenues and expenses , without consideration of the cash impact of these transactions , can jeopardize the ability of users of the financial statements to make well-informed decisions . Some investors say that “ cash is king , ” meaning that they think a company ’ s cash flow is more important than its net income in determining investment opportunities . Companies go bankrupt because they run out of cash . Financial statement users should be able to develop a picture of how well a company ’ s net income generates cash and the sources and uses of a company ’ s cash . From the statement of cash flows , it becomes possible to reconcile income on the income statement to the cash actually generated during the same period . Having cash alone is not important , but the source and use of cash are also important , specifically where the cash is coming from . <hl> If the business is generating cash from operations ( selling products and services ) , that is positive . <hl> If the company only has cash as it is taking out loans and selling assets , one must be careful in their analysis .", "hl_sentences": "Cash flows from operating activities arise from the activities a business uses to produce net income . For example , operating cash flows include cash sources from sales and cash used to purchase inventory and to pay for operating expenses such as salaries and utilities . If the business is generating cash from operations ( selling products and services ) , that is positive .", "question": { "cloze_format": "The transaction that would be part of the operating section is ___ .", "normal_format": "Which of these transactions would be part of the operating section?", "question_choices": [ "land purchased, with note payable", "sales of product, for cash", "cash paid for purchase of equipment", "dividend payments to shareholders, paid in cash" ], "question_id": "fs-idm259979696", "question_text": "Which of these transactions would be part of the operating section?" }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 2, "ans_text": "cash paid for purchase of equipment" }, "bloom": null, "hl_context": "Cash flows from investing activities are cash business transactions related to a business ’ investments in long-term assets . They can usually be identified from changes in the Fixed Assets section of the long-term assets section of the balance sheet . <hl> Some examples of investing cash flows are payments for the purchase of land , buildings , equipment , and other investment assets and cash receipts from the sale of land , buildings , equipment , and other investment assets . <hl>", "hl_sentences": "Some examples of investing cash flows are payments for the purchase of land , buildings , equipment , and other investment assets and cash receipts from the sale of land , buildings , equipment , and other investment assets .", "question": { "cloze_format": "The transaction that would be part of the investing section is ___.", "normal_format": "Which of these transactions would be part of the investing section?", "question_choices": [ "land purchased, with note payable", "sales of product, for cash", "cash paid for purchase of equipment", "dividend payments to shareholders, paid in cash" ], "question_id": "fs-idm256173648", "question_text": "Which of these transactions would be part of the investing section?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 1, "ans_text": "B" }, "bloom": null, "hl_context": "<hl> Increases in current assets indicate a decrease in cash , because either ( 1 ) cash was paid to generate another current asset , such as inventory , or ( 2 ) revenue was accrued , but not yet collected , such as accounts receivable . <hl> In the first scenario , the use of cash to increase the current assets is not reflected in the net income reported on the income statement . In the second scenario , revenue is included in the net income on the income statement , but the cash has not been received by the end of the period . <hl> In both cases , current assets increased and net income was reported on the income statement greater than the actual net cash impact from the related operating activities . <hl> To reconcile net income to cash flow from operating activities , subtract increases in current assets .", "hl_sentences": "Increases in current assets indicate a decrease in cash , because either ( 1 ) cash was paid to generate another current asset , such as inventory , or ( 2 ) revenue was accrued , but not yet collected , such as accounts receivable . In both cases , current assets increased and net income was reported on the income statement greater than the actual net cash impact from the related operating activities .", "question": { "cloze_format": "The effect on cash when current noncash operating assets increase is that ___ .", "normal_format": "What is the effect on cash when current noncash operating assets increase?", "question_choices": [ "Cash increases by the same amount.", "Cash decreases by the same amount.", "Cash decreases by twice as much.", "Cash does not change." ], "question_id": "fs-idm259310592", "question_text": "What is the effect on cash when current noncash operating assets increase?" }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 0, "ans_text": "Cash increases by the same amount." }, "bloom": null, "hl_context": "<hl> Increases in current liabilities indicate an increase in cash , since these liabilities generally represent ( 1 ) expenses that have been accrued , but not yet paid , or ( 2 ) deferred revenues that have been collected , but not yet recorded as revenue . <hl> In the case of accrued expenses , costs have been reported as expenses on the income statement , whereas the deferred revenues would arise when cash was collected in advance , but the revenue was not yet earned , so the payment would not be reflected on the income statement . In both cases , these increases in current liabilities signify cash collections that exceed net income from related activities . To reconcile net income to cash flow from operating activities , add increases in current liabilities .", "hl_sentences": "Increases in current liabilities indicate an increase in cash , since these liabilities generally represent ( 1 ) expenses that have been accrued , but not yet paid , or ( 2 ) deferred revenues that have been collected , but not yet recorded as revenue .", "question": { "cloze_format": "The effect on cash when current liabilities increase is that ___.", "normal_format": "What is the effect on cash when current liabilities increase?", "question_choices": [ "Cash increases by the same amount.", "Cash decreases by the same amount.", "Cash decreases by twice as much.", "Cash does not change." ], "question_id": "fs-idm257070144", "question_text": "What is the effect on cash when current liabilities increase?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 0, "ans_text": "A" }, "bloom": null, "hl_context": "<hl> Decreases in current assets indicate lower net income compared to cash flows from ( 1 ) prepaid assets and ( 2 ) accrued revenues . <hl> For decreases in prepaid assets , using up these assets shifts these costs that were recorded as assets over to current period expenses that then reduce net income for the period . Cash was paid to obtain the prepaid asset in a prior period . <hl> Thus , cash from operating activities must be increased to reflect the fact that these expenses reduced net income on the income statement , but cash was not paid this period . <hl> Secondarily , decreases in accrued revenue accounts indicates that cash was collected in the current period but was recorded as revenue on a previous period ’ s income statement . In both scenarios , the net income reported on the income statement was lower than the actual net cash effect of the transactions . To reconcile net income to cash flow from operating activities , add decreases in current assets .", "hl_sentences": "Decreases in current assets indicate lower net income compared to cash flows from ( 1 ) prepaid assets and ( 2 ) accrued revenues . Thus , cash from operating activities must be increased to reflect the fact that these expenses reduced net income on the income statement , but cash was not paid this period .", "question": { "cloze_format": "The effect on cash when current noncash operating assets decrease is that ___.", "normal_format": "What is the effect on cash when current noncash operating assets decrease?", "question_choices": [ "Cash increases by the same amount.", "Cash decreases by the same amount.", "Cash decreases by twice as much.", "Cash does not change." ], "question_id": "fs-idm252676080", "question_text": "What is the effect on cash when current noncash operating assets decrease?" }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 1, "ans_text": "Cash decreases by the same amount." }, "bloom": null, "hl_context": "<hl> Current Operating Liability Decrease Decreases in current liabilities indicate a decrease in cash relating to ( 1 ) accrued expenses , or ( 2 ) deferred revenues . <hl> In the first instance , cash would have been expended to accomplish a decrease in liabilities arising from accrued expenses , yet these cash payments would not be reflected in the net income on the income statement . In the second instance , a decrease in deferred revenue means that some revenue would have been reported on the income statement that was collected in a previous period . <hl> As a result , cash flows from operating activities must be decreased by any reduction in current liabilities , to account for ( 1 ) cash payments to creditors that are higher than the expense amounts on the income statement , or ( 2 ) amounts collected that are lower than the amounts reflected as income on the income statement . <hl> To reconcile net income to cash flow from operating activities , subtract decreases in current liabilities .", "hl_sentences": "Current Operating Liability Decrease Decreases in current liabilities indicate a decrease in cash relating to ( 1 ) accrued expenses , or ( 2 ) deferred revenues . As a result , cash flows from operating activities must be decreased by any reduction in current liabilities , to account for ( 1 ) cash payments to creditors that are higher than the expense amounts on the income statement , or ( 2 ) amounts collected that are lower than the amounts reflected as income on the income statement .", "question": { "cloze_format": "The effect on cash when current liabilities decrease is that ___ .", "normal_format": "What is the effect on cash when current liabilities decrease?", "question_choices": [ "Cash increases by the same amount.", "Cash decreases by the same amount.", "Cash decreases by twice as much.", "Cash does not change." ], "question_id": "fs-idm249327504", "question_text": "What is the effect on cash when current liabilities decrease?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 0, "ans_text": "A" }, "bloom": null, "hl_context": "<hl> Gains and / or losses on the disposal of long-term assets are included in the calculation of net income , but cash obtained from disposing of long-term assets is a cash flow from an investing activity . <hl> <hl> Because the disposition gain or loss is not related to normal operations , the adjustment needed to arrive at cash flow from operating activities is a reversal of any gains or losses that are included in the net income total . <hl> <hl> A gain is subtracted from net income and a loss is added to net income to reconcile to cash from operating activities . <hl> Propensity ’ s income statement for the year 2018 includes a gain on sale of land , in the amount of $ 4,800 , so a reversal is accomplished by subtracting the gain from net income . On Propensity ’ s statement of cash flows , this amount is shown in the Cash Flows from Operating Activities section as Gain on Sale of Plant Assets .", "hl_sentences": "Gains and / or losses on the disposal of long-term assets are included in the calculation of net income , but cash obtained from disposing of long-term assets is a cash flow from an investing activity . Because the disposition gain or loss is not related to normal operations , the adjustment needed to arrive at cash flow from operating activities is a reversal of any gains or losses that are included in the net income total . A gain is subtracted from net income and a loss is added to net income to reconcile to cash from operating activities .", "question": { "cloze_format": "___ would trigger a subtraction in the indirect operating section.", "normal_format": "Which of the following would trigger a subtraction in the indirect operating section?", "question_choices": [ "gain on sale of investments", "depreciation expense", "decrease in accounts receivable", "decrease in bonds payable" ], "question_id": "fs-idm251311808", "question_text": "Which of the following would trigger a subtraction in the indirect operating section?" }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 0, "ans_text": "sale of investments" }, "bloom": null, "hl_context": "<hl> Cash flows from investing activities are cash business transactions related to a business ’ investments in long-term assets . <hl> They can usually be identified from changes in the Fixed Assets section of the long-term assets section of the balance sheet . <hl> Some examples of investing cash flows are payments for the purchase of land , buildings , equipment , and other investment assets and cash receipts from the sale of land , buildings , equipment , and other investment assets . <hl>", "hl_sentences": "Cash flows from investing activities are cash business transactions related to a business ’ investments in long-term assets . Some examples of investing cash flows are payments for the purchase of land , buildings , equipment , and other investment assets and cash receipts from the sale of land , buildings , equipment , and other investment assets .", "question": { "cloze_format": "___ represents a source of cash in the investing section.", "normal_format": "Which of the following represents a source of cash in the investing section?", "question_choices": [ "sale of investments", "depreciation expense", "decrease in accounts receivable", "decrease in bonds payable" ], "question_id": "fs-idm251373776", "question_text": "Which of the following represents a source of cash in the investing section?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 3, "ans_text": "D" }, "bloom": null, "hl_context": "<hl> Decreases in net cash flow from financing normally occur when ( 1 ) long-term liabilities , such as notes payable or bonds payable are repaid , ( 2 ) when the company reacquires some of its own stock ( treasury stock ) , or ( 3 ) when the company pays dividends to shareholders . <hl> In the case of Propensity Company , the decreases in cash resulted from notes payable principal repayments and cash dividend payments .", "hl_sentences": "Decreases in net cash flow from financing normally occur when ( 1 ) long-term liabilities , such as notes payable or bonds payable are repaid , ( 2 ) when the company reacquires some of its own stock ( treasury stock ) , or ( 3 ) when the company pays dividends to shareholders .", "question": { "cloze_format": "The ___ would be included in the financing section.", "normal_format": "Which of the following would be included in the financing section?", "question_choices": [ "loss on sale of investments", "depreciation expense", "increase in notes receivable", "decrease in notes payable" ], "question_id": "fs-idm248753360", "question_text": "Which of the following would be included in the financing section?" }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 2, "ans_text": "C" }, "bloom": null, "hl_context": "<hl> The absence of free cash flow is an indicator of severe liquidity concern for Propensity Company and could be an early indicator that the company may not be able to continue operations . <hl> This could also be a one-time occurrence , in a year where a large capital investment was planned , to be financed with resources from the company ’ s capital reserves from previous years ’ profits . In such a case , the negative free cash flow would not be an issue of concern . Ethical Considerations Cash Flow Analysis Cash is required to pay the bills . All businesses need to have a clear picture of available cash so they can plan and pay their bills . The statement of cash flows allows investors direct insight into the actual activity on the company ’ s cash balances . Mark A . Siegel wrote in The CPA Journal that “ as Wall Street analysts have lost faith in earnings-based metrics in the wake of Enron , WorldCom , and others , many have gravitated toward the cash flow statement . <hl> Companies are regularly evaluated on the basis of free cash flow yield and other measures of cash generation . ” 3 The operating cash flow ratio , and the cash flow margin ratio , and the other cash flow – related metrics discussed allow an investor and other users of the financial statements to analyze financial statement data to see a company ’ s ability to pay for current debt and assess its operational cash flow to function as a going concern . <hl> 4 This helps investors and other users of the financial statements ensure the veracity of a company ’ s financial statements and its ability to pay its bills . 3 Marc A . Siegel . “ Accounting Shenanigans on the Cash Flow Statement . ” CPA Journal . March 2006 . http://archives.cpajournal.com/2006/306/essentials/p38.htm 4 Steven D . Jones . “ Why Cash Flow Matters in Evaluating a Company . ” The Wall Street Journal . August 11 , 2016 . https://www.wsj.com/articles/SB997466275287616386 . Miriam Gottfried . “ Spoiler Alert for Netflix : Debt and Cash Flow Matter . ” The Wall Street Journal . April 17 , 2017 . https://www.wsj.com/articles/spoiler-alert-for-netflix-debt-and-cash-flow-matter-1492468397 Cash flow ratio analysis allows financial statement users to see the company ’ s liquidity position from a clearer perspective . <hl> The ratios presented in this section focus on free cash flow , calculated as operating cash , reduced by expected capital expenditures and by cash dividends payments . <hl> <hl> The free cash flow value is thus an adaptation of cash flow from operating activities . <hl> <hl> The result obtained in the initial free cash flow calculation is then used to calculate the free cash flow to sales ratio , which is the ratio of free cash flow to sales revenue , and the free cash flow to assets ratio , which is the ratio of free cash flow to total assets . <hl> <hl> These three tools give indicators about the company ’ s flexibility and agility , which equates to their ability to seize opportunities in the future , as they arise . <hl>", "hl_sentences": "The absence of free cash flow is an indicator of severe liquidity concern for Propensity Company and could be an early indicator that the company may not be able to continue operations . Companies are regularly evaluated on the basis of free cash flow yield and other measures of cash generation . ” 3 The operating cash flow ratio , and the cash flow margin ratio , and the other cash flow – related metrics discussed allow an investor and other users of the financial statements to analyze financial statement data to see a company ’ s ability to pay for current debt and assess its operational cash flow to function as a going concern . The ratios presented in this section focus on free cash flow , calculated as operating cash , reduced by expected capital expenditures and by cash dividends payments . The free cash flow value is thus an adaptation of cash flow from operating activities . The result obtained in the initial free cash flow calculation is then used to calculate the free cash flow to sales ratio , which is the ratio of free cash flow to sales revenue , and the free cash flow to assets ratio , which is the ratio of free cash flow to total assets . These three tools give indicators about the company ’ s flexibility and agility , which equates to their ability to seize opportunities in the future , as they arise .", "question": { "cloze_format": "___ is a stronger indicator of cash flow flexibility.", "normal_format": "Which of the following is a stronger indicator of cash flow flexibility?", "question_choices": [ "cash flow from operating activities", "cash flow to sales ratio", "free cash flow", "all three indicate comparable degrees of flexibility" ], "question_id": "fs-idm381045296", "question_text": "Which of the following is a stronger indicator of cash flow flexibility?" }, "references_are_paraphrase": null } ]
16
16.1 Explain the Purpose of the Statement of Cash Flows The statement of cash flows is a financial statement listing the cash inflows and cash outflows for the business for a period of time. Cash flow represents the cash receipts and cash disbursements as a result of business activity. The statement of cash flows enables users of the financial statements to determine how well a company’s income generates cash and to predict the potential of a company to generate cash in the future. Accrual accounting creates timing differences between income statement accounts and cash. A revenue transaction may be recorded in a different fiscal year than the year the cash related to that revenue is received. One purpose of the statement of cash flows is that users of the financial statements can see the amount of cash inflows and outflows during a year in addition to the amount of revenue and expense shown on the income statement. This is important because cash flows often differ significantly from accrual basis net income. For example, assume in 2019 that Amazon showed a loss of approximately $720 million, yet Amazon ’s cash balance increased by more than $91 million. Much of the change can be explained by timing differences between income statement accounts and cash receipts and distributions. A related use of the statement of cash flows is that it provides information about the quality of a company’s net income. A company that has records that show significantly less cash inflow on the statement of cash flows than the reported net income on the income statement could very well be reporting revenue for which cash will never be received from the customer or underreporting expenses. A third use of the statement of cash flows is that it provides information about a company’s sources and uses of cash not related to the income statement. For example, assume in 2019 that Amazon spent $287 million on purchasing fixed assets and almost $370 million acquiring other businesses. This indicated to financial statement users that Amazon was expanding even as it was losing money. Investors must have thought that spending was good news as Amazon was able to raise more than $1 billion in borrowings or stock issuances in 2019. Ethical Considerations Cash Flow Statement Reporting US generally accepted accounting principles (GAAP) has codified how cash flow statements are to be presented to users of financial statements. This was codified in Topic 230: Statement of Cash Flows as part of US GAAP. 1 Accountants in the United States should follow US GAAP. Accountants working internationally must report in accordance with International Accounting Standard (IAS) 7 Statement of Cash Flows. 2 The ethical accountant understands the users of a company’s financial statement and properly prepares a Statement of Cash Flow. There is often more than one way that financial statements can be presented, such as US GAAP and International Financial Reporting Standards (IFRS). What if a company under US GAAP showed reporting issues on their financial statements and switched to IFRS where results looked better. Is this proper? Does this occur? 1 Financial Accounting Standards Board (FASB). “Statement of Cash Flows (Topic 230) Classification of Certain Cash Receipts and Cash Payments.” An Amendment of the FASB Accounting Standards Codification . August 2016. https://asc.fasb.org/imageRoot/55/95454355.pdf 2 International Financial Reporting Standards (IFRS). “IAS 7 Statement of Cash Flows.” n.d. https://www.ifrs.org/issued-standards/list-of-standards/ias-7-statement-of-cash-flows/ The statement of cash flows identifies the sources of cash as well as the uses of cash, for the period being reported, which leads the user of the financial statement to the period’s net cash flows , which is a method used to determine profitability by measuring the difference between an entity’s cash inflows and cash outflows. The statement answers the following two questions: What are the sources of cash (where does the cash come from)? What are the uses of cash (where does the cash go)? A positive net cash flow indicates an increase in cash during the reporting period, whereas a negative net cash flow indicates a decrease in cash during the reporting period. The statement of cash flows is also used as a predictive tool for external users of the financial statements, for estimated future cash flows, based on cash flow results in the past. Link to Learning This video from Khan Academy explains cash flows in a unique way. Approaches to Preparing the Statement of Cash Flows The statement of cash flows can be prepared using the indirect approach or the direct approach. The indirect method approach reconciles net income to cash flows by subtracting noncash expenses and adjusting for changes in current assets and liabilities, which reflects timing differences between accrual-based net income and cash flows. A noncash expense is an expense that reduces net income but is not associated with a cash flow; the most common example is depreciation expense. The direct method lists net cash flows from revenue and expenses, whereby accrual basis revenue and expenses are converted to cash basis collections and payments. Because the vast majority of financial statements are presented using the indirect method, the indirect approach will be demonstrated within the chapter, and the direct method will be demonstrated in Appendix: Prepare a Completed Statement of Cash Flows Using the Direct Method . Link to Learning AccountingCoach is a great resource for many accounting topics, including cash flow issues. 16.2 Differentiate between Operating, Investing, and Financing Activities The statement of cash flows presents sources and uses of cash in three distinct categories: cash flows from operating activities , cash flows from investing activities , and cash flows from financing activities . Financial statement users are able to assess a company’s strategy and ability to generate a profit and stay in business by assessing how much a company relies on operating, investing, and financing activities to produce its cash flows. Think It Through Classification of Cash Flows Makes a Difference Assume you are the chief financial officer of T-Shirt Pros, a small business that makes custom-printed T-shirts. While reviewing the financial statements that were prepared by company accountants, you discover an error. During this period, the company had purchased a warehouse building, in exchange for a $200,000 note payable. The company’s policy is to report noncash investing and financing activities in a separate statement, after the presentation of the statement of cash flows. This noncash investing and financing transaction was inadvertently included in both the financing section as a source of cash, and the investing section as a use of cash. T-Shirt Pros’ statement of cash flows, as it was prepared by the company accountants, reported the following for the period, and had no other capital expenditures. Because of the misplacement of the transaction, the calculation of free cash flow by outside analysts could be affected significantly. Free cash flow is calculated as cash flow from operating activities, reduced by capital expenditures, the value for which is normally obtained from the investing section of the statement of cash flows. As their manager, would you treat the accountants’ error as a harmless misclassification, or as a major blunder on their part? Explain. Cash Flows from Operating Activities Cash flows from operating activities arise from the activities a business uses to produce net income. For example, operating cash flows include cash sources from sales and cash used to purchase inventory and to pay for operating expenses such as salaries and utilities. Operating cash flows also include cash flows from interest and dividend revenue interest expense, and income tax. Cash Flows from Investing Activities Cash flows from investing activities are cash business transactions related to a business’ investments in long-term assets. They can usually be identified from changes in the Fixed Assets section of the long-term assets section of the balance sheet. Some examples of investing cash flows are payments for the purchase of land, buildings, equipment, and other investment assets and cash receipts from the sale of land, buildings, equipment, and other investment assets. Cash Flows from Financing Activities Cash flows from financing activities are cash transactions related to the business raising money from debt or stock, or repaying that debt. They can be identified from changes in long-term liabilities and equity. Examples of financing cash flows include cash proceeds from issuance of debt instruments such as notes or bonds payable, cash proceeds from issuance of capital stock, cash payments for dividend distributions, principal repayment or redemption of notes or bonds payable, or purchase of treasury stock. Cash flows related to changes in equity can be identified on the Statement of Stockholder’s Equity, and cash flows related to long-term liabilities can be identified by changes in long-term liabilities on the balance sheet. Concepts In Practice Can a Negative Be Positive? Investors do not always take a negative cash flow as a negative. For example, assume in 2018 Amazon showed a loss of $124 billion and a net cash outflow of $262 billion from investing activities. Yet during the same year, Amazon was able to raise a net $254 billion through financing. Why would investors and lenders be willing to place money with Amazon ? For one thing, despite having a net loss, Amazon produced $31 billion cash from operating activities. Much of this was through delaying payment on inventories. Amazon ’s accounts payable increased by $78 billion, while its inventory increased by $20 billion. Another reason lenders and investors were willing to fund Amazon is that investing payments are often signs of a company growing. Assume that in 2018 Amazon paid almost $50 billion to purchase fixed assets and to acquire other businesses; this is a signal of a company that is growing. Lenders and investors interpreted Amazon ’s cash flows as evidence that Amazon would be able to produce positive net income in the future. In fact, Amazon had net income of $19 billion in 2017. Furthermore, Amazon is still showing growth through its statement of cash flows; it spent about $26 billion in fixed equipment and acquisitions. 16.3 Prepare the Statement of Cash Flows Using the Indirect Method The statement of cash flows is prepared by following these steps: Step 1: Determine Net Cash Flows from Operating Activities Using the indirect method , operating net cash flow is calculated as follows: Begin with net income from the income statement. Add back noncash expenses, such as depreciation, amortization, and depletion. Remove the effect of gains and/or losses from disposal of long-term assets, as cash from the disposal of long-term assets is shown under investing cash flows. Adjust for changes in current assets and liabilities to remove accruals from operating activities. Step 2: Determine Net Cash Flows from Investing Activities Investing net cash flow includes cash received and cash paid relating to long-term assets. Step 3: Present Net Cash Flows from Financing Activities Financing net cash flow includes cash received and cash paid relating to long-term liabilities and equity. Step 4: Reconcile Total Net Cash Flows to Change in Cash Balance during the Period To reconcile beginning and ending cash balances: The net cash flows from the first three steps are combined to be total net cash flow. The beginning cash balance is presented from the prior year balance sheet. Total net cash flow added to the beginning cash balance equals the ending cash balance. Step 5: Present Noncash Investing and Financing Transactions Transactions that do not affect cash but do affect long-term assets, long-term debt, and/or equity are disclosed, either as a notation at the bottom of the statement of cash flow, or in the notes to the financial statements. The remainder of this section demonstrates preparation of the statement of cash flows of the company whose financial statements are shown in Figure 16.2 , Figure 16.3 , and Figure 16.4 . Additional Information: Propensity Company sold land with an original cost of $10,000, for $14,800 cash. A new parcel of land was purchased for $20,000, in exchange for a note payable. Plant assets were purchased for $40,000 cash. Propensity declared and paid a $440 cash dividend to shareholders. Propensity issued common stock in exchange for $45,000 cash. Prepare the Operating Activities Section of the Statement of Cash Flows Using the Indirect Method In the following sections, specific entries are explained to demonstrate the items that support the preparation of the operating activities section of the Statement of Cash Flows (Indirect Method) for the Propensity Company example financial statements. Begin with net income from the income statement. Add back noncash expenses, such as depreciation, amortization, and depletion. Reverse the effect of gains and/or losses from investing activities. Adjust for changes in current assets and liabilities, to reflect how those changes impact cash in a way that is different than is reported in net income.0 Start with Net Income The operating activities cash flow is based on the company’s net income, with adjustments for items that affect cash differently than they affect net income. The net income on the Propensity Company income statement for December 31, 2018, is $4,340. On Propensity’s statement of cash flows, this amount is shown in the Cash Flows from Operating Activities section as Net Income. Add Back Noncash Expenses Net income includes deductions for noncash expenses. To reconcile net income to cash flow from operating activities, these noncash items must be added back, because no cash was expended relating to that expense. The sole noncash expense on Propensity Company’s income statement, which must be added back , is the depreciation expense of $14,400. On Propensity’s statement of cash flows, this amount is shown in the Cash Flows from Operating Activities section as an adjustment to reconcile net income to net cash flow from operating activities. Reverse the Effect of Gains and/or Losses Gains and/or losses on the disposal of long-term assets are included in the calculation of net income, but cash obtained from disposing of long-term assets is a cash flow from an investing activity. Because the disposition gain or loss is not related to normal operations, the adjustment needed to arrive at cash flow from operating activities is a reversal of any gains or losses that are included in the net income total. A gain is subtracted from net income and a loss is added to net income to reconcile to cash from operating activities. Propensity’s income statement for the year 2018 includes a gain on sale of land, in the amount of $4,800, so a reversal is accomplished by subtracting the gain from net income. On Propensity’s statement of cash flows, this amount is shown in the Cash Flows from Operating Activities section as Gain on Sale of Plant Assets. Adjust for Changes in Current Assets and Liabilities Because the Balance Sheet and Income Statement reflect the accrual basis of accounting, whereas the statement of cash flows considers the incoming and outgoing cash transactions, there are continual differences between (1) cash collected and paid and (2) reported revenue and expense on these statements. Changes in the various current assets and liabilities can be determined from analysis of the company’s comparative balance sheet, which lists the current period and previous period balances for all assets and liabilities. The following four possibilities offer explanations of the type of difference that might arise, and demonstrate examples from Propensity Company’s statement of cash flows, which represent typical differences that arise relating to these current assets and liabilities. Increase in Noncash Current Assets Increases in current assets indicate a decrease in cash, because either (1) cash was paid to generate another current asset, such as inventory, or (2) revenue was accrued, but not yet collected, such as accounts receivable. In the first scenario, the use of cash to increase the current assets is not reflected in the net income reported on the income statement. In the second scenario, revenue is included in the net income on the income statement, but the cash has not been received by the end of the period. In both cases, current assets increased and net income was reported on the income statement greater than the actual net cash impact from the related operating activities. To reconcile net income to cash flow from operating activities, subtract increases in current assets. Propensity Company had two instances of increases in current assets. One was an increase of $700 in prepaid insurance, and the other was an increase of $2,500 in inventory. In both cases, the increases can be explained as additional cash that was spent, but which was not reflected in the expenses reported on the income statement. Decrease in Noncash Current Assets Decreases in current assets indicate lower net income compared to cash flows from (1) prepaid assets and (2) accrued revenues. For decreases in prepaid assets, using up these assets shifts these costs that were recorded as assets over to current period expenses that then reduce net income for the period. Cash was paid to obtain the prepaid asset in a prior period. Thus, cash from operating activities must be increased to reflect the fact that these expenses reduced net income on the income statement, but cash was not paid this period. Secondarily, decreases in accrued revenue accounts indicates that cash was collected in the current period but was recorded as revenue on a previous period’s income statement. In both scenarios, the net income reported on the income statement was lower than the actual net cash effect of the transactions. To reconcile net income to cash flow from operating activities, add decreases in current assets. Propensity Company had a decrease of $4,500 in accounts receivable during the period, which normally results only when customers pay the balance, they owe the company at a faster rate than they charge new account balances. Thus, the decrease in receivable identifies that more cash was collected than was reported as revenue on the income statement. Thus, an addback is necessary to calculate the cash flow from operating activities. Current Operating Liability Increase Increases in current liabilities indicate an increase in cash, since these liabilities generally represent (1) expenses that have been accrued, but not yet paid, or (2) deferred revenues that have been collected, but not yet recorded as revenue. In the case of accrued expenses, costs have been reported as expenses on the income statement, whereas the deferred revenues would arise when cash was collected in advance, but the revenue was not yet earned, so the payment would not be reflected on the income statement. In both cases, these increases in current liabilities signify cash collections that exceed net income from related activities. To reconcile net income to cash flow from operating activities, add increases in current liabilities. Propensity Company had an increase in the current operating liability for salaries payable, in the amount of $400. The payable arises, or increases, when an expense is recorded but the balance due is not paid at that time. An increase in salaries payable therefore reflects the fact that salaries expenses on the income statement are greater than the cash outgo relating to that expense. This means that net cash flow from operating is greater than the reported net income, regarding this cost. Current Operating Liability Decrease Decreases in current liabilities indicate a decrease in cash relating to (1) accrued expenses, or (2) deferred revenues. In the first instance, cash would have been expended to accomplish a decrease in liabilities arising from accrued expenses, yet these cash payments would not be reflected in the net income on the income statement. In the second instance, a decrease in deferred revenue means that some revenue would have been reported on the income statement that was collected in a previous period. As a result, cash flows from operating activities must be decreased by any reduction in current liabilities, to account for (1) cash payments to creditors that are higher than the expense amounts on the income statement, or (2) amounts collected that are lower than the amounts reflected as income on the income statement. To reconcile net income to cash flow from operating activities, subtract decreases in current liabilities. Propensity Company had a decrease of $1,800 in the current operating liability for accounts payable. The fact that the payable decreased indicates that Propensity paid enough payments during the period to keep up with new charges, and also to pay down on amounts payable from previous periods. Therefore, the company had to have paid more in cash payments than the amounts shown as expense on the Income Statements, which means net cash flow from operating activities is lower than the related net income. Analysis of Change in Cash Although the net income reported on the income statement is an important tool for evaluating the success of the company’s efforts for the current period and their viability for future periods, the practical effectiveness of management is not adequately revealed by the net income alone. The net cash flows from operating activities adds this essential facet of information to the analysis, by illuminating whether the company’s operating cash sources were adequate to cover their operating cash uses. When combined with the cash flows produced by investing and financing activities, the operating activity cash flow indicates the feasibility of continuance and advancement of company plans. Determining Net Cash Flow from Operating Activities (Indirect Method) Net cash flow from operating activities is the net income of the company, adjusted to reflect the cash impact of operating activities. Positive net cash flow generally indicates adequate cash flow margins exist to provide continuity or ensure survival of the company. The magnitude of the net cash flow, if large, suggests a comfortable cash flow cushion, while a smaller net cash flow would signify an uneasy comfort cash flow zone. When a company’s net cash flow from operations reflects a substantial negative value, this indicates that the company’s operations are not supporting themselves and could be a warning sign of possible impending doom for the company. Alternatively, a small negative cash flow from operating might serve as an early warning that allows management to make needed corrections, to ensure that cash sources are increased to amounts in excess of cash uses, for future periods. For Propensity Company, beginning with net income of $4,340, and reflecting adjustments of $9,500, delivers a net cash flow from operating activities of $13,840. Your Turn Cash Flow from Operating Activities Assume you own a specialty bakery that makes gourmet cupcakes. Excerpts from your company’s financial statements are shown. How much cash flow from operating activities did your company generate? Solution Think It Through Explaining Changes in Cash Balance Assume that you are the chief financial officer of a company that provides accounting services to small businesses. You are called upon by the board of directors to explain why your cash balance did not increase much from the beginning of 2018 until the end of 2018, since the company produced a reasonably strong profit for the year, with a net income of $88,000. Further assume that there were no investing or financing transactions, and no depreciation expense for 2018. What is your response? Provide the calculations to back up your answer. Prepare the Investing and Financing Activities Sections of the Statement of Cash Flows Preparation of the investing and financing sections of the statement of cash flows is an identical process for both the direct and indirect methods, since only the technique used to arrive at net cash flow from operating activities is affected by the choice of the direct or indirect approach. The following sections discuss specifics regarding preparation of these two nonoperating sections, as well as notations about disclosure of long-term noncash investing and/or financing activities. Changes in the various long-term assets, long-term liabilities, and equity can be determined from analysis of the company’s comparative balance sheet, which lists the current period and previous period balances for all assets and liabilities. Investing Activities Cash flows from investing activities always relate to long-term asset transactions and may involve increases or decreases in cash relating to these transactions. The most common of these activities involve purchase or sale of property, plant, and equipment, but other activities, such as those involving investment assets and notes receivable, also represent cash flows from investing. Changes in long-term assets for the period can be identified in the Noncurrent Assets section of the company’s comparative balance sheet, combined with any related gain or loss that is included on the income statement. In the Propensity Company example, the investing section included two transactions involving long-term assets, one of which increased cash, while the other one decreased cash, for a total net cash flow from investing of ($25,200). Analysis of Propensity Company’s comparative balance sheet revealed changes in land and plant assets. Further investigation identified that the change in long-term assets arose from three transactions: Investing activity: A tract of land that had an original cost of $10,000 was sold for $14,800. Investing activity: Plant assets were purchased, for $40,000 cash. Noncash investing and financing activity: A new parcel of land was acquired, in exchange for a $20,000 note payable. Details relating to the treatment of each of these transactions are provided in the following sections. Investing Activities Leading to an Increase in Cash Increases in net cash flow from investing usually arise from the sale of long-term assets. The cash impact is the cash proceeds received from the transaction, which is not the same amount as the gain or loss that is reported on the income statement. Gain or loss is computed by subtracting the asset’s net book value from the cash proceeds. Net book value is the asset’s original cost, less any related accumulated depreciation. Propensity Company sold land, which was carried on the balance sheet at a net book value of $10,000, representing the original purchase price of the land, in exchange for a cash payment of $14,800. The data set explained these net book value and cash proceeds facts for Propensity Company. However, had these facts not been stipulated in the data set, the cash proceeds could have been determined by adding the reported $4,800 gain on the sale to the $10,000 net book value of the asset given up, to arrive at cash proceeds from the sale. Investing Activities Leading to a Decrease in Cash Decreases in net cash flow from investing normally occur when long-term assets are purchased using cash. For example, in the Propensity Company example, there was a decrease in cash for the period relating to a simple purchase of new plant assets, in the amount of $40,000. Financing Activities Cash flows from financing activities always relate to either long-term debt or equity transactions and may involve increases or decreases in cash relating to these transactions. Stockholders’ equity transactions, like stock issuance, dividend payments, and treasury stock buybacks are very common financing activities. Debt transactions, such as issuance of bonds payable or notes payable, and the related principal payback of them, are also frequent financing events. Changes in long-term liabilities and equity for the period can be identified in the Noncurrent Liabilities section and the Stockholders’ Equity section of the company’s Comparative Balance Sheet, and in the retained earnings statement. In the Propensity Company example, the financing section included three transactions. One long-term debt transaction decreased cash. Two transactions related to equity, one of which increased cash, while the other one decreased cash, for a total net cash flow from financing of $34,560. Analysis of Propensity Company’s Comparative Balance Sheet revealed changes in notes payable and common stock, while the retained earnings statement indicated that dividends were distributed to stockholders. Further investigation identified that the change in long-term liabilities and equity arose from three transactions: Financing activity: Principal payments of $10,000 were paid on notes payable. Financing activity: New shares of common stock were issued, in the amount of $45,000. Financing activity: Dividends of $440 were paid to shareholders. Specifics about each of these three transactions are provided in the following sections. Financing Activities Leading to an Increase in Cash Increases in net cash flow from financing usually arise when the company issues share of stock, bonds, or notes payable to raise capital for cash flow. Propensity Company had one example of an increase in cash flows, from the issuance of common stock. Financing Activities Leading to a Decrease in Cash Decreases in net cash flow from financing normally occur when (1) long-term liabilities, such as notes payable or bonds payable are repaid, (2) when the company reacquires some of its own stock (treasury stock), or (3) when the company pays dividends to shareholders. In the case of Propensity Company, the decreases in cash resulted from notes payable principal repayments and cash dividend payments. Noncash Investing and Financing Activities Sometimes transactions can be very important to the company, yet not involve any initial change to cash. Disclosure of these noncash investing and financing transactions can be included in the notes to the financial statements, or as a notation at the bottom of the statement of cash flows, after the entire statement has been completed. These noncash activities usually involve one of the following scenarios: exchanges of long-term assets for long-term liabilities or equity, or exchanges of long-term liabilities for equity. Propensity Company had a noncash investing and financing activity, involving the purchase of land (investing activity) in exchange for a $20,000 note payable (financing activity). Summary of Investing and Financing Transactions on the Cash Flow Statement Investing and financing transactions are critical activities of business, and they often represent significant amounts of company equity, either as sources or uses of cash. Common activities that must be reported as investing activities are purchases of land, equipment, stocks, and bonds, while financing activities normally relate to the company’s funding sources, namely, creditors and investors. These financing activities could include transactions such as borrowing or repaying notes payable, issuing or retiring bonds payable, or issuing stock or reacquiring treasury stock, to name a few instances. Your Turn Cash Flow from Investing Activities Assume your specialty bakery makes gourmet cupcakes and has been operating out of rented facilities in the past. You owned a piece of land that you had planned to someday use to build a sales storefront. This year your company decided to sell the land and instead buy a building, resulting in the following transactions. What are the cash flows from investing activities relating to these transactions? Solution Note: Interest earned on investments is an operating activity. 16.4 Prepare the Completed Statement of Cash Flows Using the Indirect Method In this section, we use the example of Virtual Co. to work through the entire process of preparing the company’s statement of cash flows using the indirect method . Virtual’s comparative balance sheet and income statement are provided as a base for the preparation of the statement of cash flows. Review Problem: Preparing the Virtual Co. Statement of Cash Flows Additional Information The following additional information is provided: Investments that originally cost $30,000 were sold for $47,500 cash. Investments were purchased for $50,000 cash. Plant assets were purchased for $66,000 cash. Cash dividends were declared and paid to shareholders in the amount of $8,000. Directions: Prepare the statement of cash flows (indirect method), for the year ended December 31, 2018. 16.5 Use Information from the Statement of Cash Flows to Prepare Ratios to Assess Liquidity and Solvency Cash flow ratio analysis allows financial statement users to see the company’s liquidity position from a clearer perspective. The ratios presented in this section focus on free cash flow , calculated as operating cash, reduced by expected capital expenditures and by cash dividends payments. The free cash flow value is thus an adaptation of cash flow from operating activities. The result obtained in the initial free cash flow calculation is then used to calculate the free cash flow to sales ratio , which is the ratio of free cash flow to sales revenue, and the free cash flow to assets ratio , which is the ratio of free cash flow to total assets. These three tools give indicators about the company’s flexibility and agility, which equates to their ability to seize opportunities in the future, as they arise. Ethical Considerations Cash Flow Analysis Cash is required to pay the bills. All businesses need to have a clear picture of available cash so they can plan and pay their bills. The statement of cash flows allows investors direct insight into the actual activity on the company’s cash balances. Mark A. Siegel wrote in The CPA Journal that “as Wall Street analysts have lost faith in earnings-based metrics in the wake of Enron, WorldCom, and others, many have gravitated toward the cash flow statement. Companies are regularly evaluated on the basis of free cash flow yield and other measures of cash generation.” 3 The operating cash flow ratio, and the cash flow margin ratio, and the other cash flow–related metrics discussed allow an investor and other users of the financial statements to analyze financial statement data to see a company’s ability to pay for current debt and assess its operational cash flow to function as a going concern. 4 This helps investors and other users of the financial statements ensure the veracity of a company’s financial statements and its ability to pay its bills. 3 Marc A. Siegel. “Accounting Shenanigans on the Cash Flow Statement.” CPA Journal . March 2006. http://archives.cpajournal.com/2006/306/essentials/p38.htm 4 Steven D. Jones. “Why Cash Flow Matters in Evaluating a Company.” The Wall Street Journal . August 11, 2016. https://www.wsj.com/articles/SB997466275287616386. Miriam Gottfried. “Spoiler Alert for Netflix: Debt and Cash Flow Matter.” The Wall Street Journal . April 17, 2017. https://www.wsj.com/articles/spoiler-alert-for-netflix-debt-and-cash-flow-matter-1492468397 Free Cash Flow Free cash flow calculations start with cash flows from operating activities, reduced by planned capital expenditures and planned cash dividend payments. In the example case demonstrated, free cash flow would be as follows: Free cash flow calculation: The absence of free cash flow is an indicator of severe liquidity concern for Propensity Company and could be an early indicator that the company may not be able to continue operations. This could also be a one-time occurrence, in a year where a large capital investment was planned, to be financed with resources from the company’s capital reserves from previous years’ profits. In such a case, the negative free cash flow would not be an issue of concern. Link to Learning This article by Investopedia presents information about how to use free cash flow to evaluate strengths of various businesses: Cash Flows to Sales The cash flows to sales ratio is computed by dividing free cash flow by sales revenue. In the Propensity Company case, free cash flow had a negative outcome, so the calculation would not be useful in this case. Cash Flows to Assets The cash flows to assets ratio is computed by dividing free cash flow by total assets. Again, when the free cash flow had a negative outcome, as it did in the Propensity Company example scenario, the calculation would not be useful Concepts In Practice Lehman Brothers: Would You Have Invested? Between 2005 and 2007, Lehman Brothers (an investment bank) increased its net income from $3.1 billion to $4.1 billion. It received nearly $42 billion interest and dividends on its investments, a primary part of its business model, in 2007 alone. It also had $7.2 billion available in cash at the end of 2007. Would you be interested in investing in Lehman Brothers ? However, Lehman Brothers went bankrupt in September 2008; it was the biggest corporate bankruptcy in history. Could investors have known? A clue would be its free cash ratio. Assuming that you would expect Lehman Brothers ’ actual capital expenditures and dividend payments from 2007 be expected in 2008, Lehman’s free cash ratio would be calculated as, in millions: Lehman Brothers invested heavily in securities created from subprime mortgages. When the subprime mortgage market collapsed in 2008, Lehman Brothers was not able to generate enough cash to stay in business. The large negative free cash flow gave warning that Lehman Brothers was a risky investment. IFRS Connection Statement of Cash Flows In every type of business across the globe, it is important to understand the business’s cash position. Analyzing cash inflows and outflows, current cash flow, and cash flow trends, and predicting future cash flows all importantly inform decision-making. The US Securities and Exchange Commission (SEC) requires the statement of cash flows as the mechanism that allows users to better assess a company’s cash position. US generally accepted accounting principles (GAAP) and International Financial Reporting Standards (IFRS) set forth rules regarding the composition and presentation of the statement of cash flows. Method: Both GAAP and IFRS recommend and encourage the direct method of preparing the statement of cash flows but allow the indirect method. Under US GAAP, if the direct method is used, a reconciliation between net income and operating income must also be presented. This reconciliation is not required under IFRS. Presentation: The three categories—Cash Flows from Operating Activities, Cash Flows from Investing Activities, and Cash Flows from Financing Activities—are required under both US GAAP and IFRS. US GAAP requires the presentation of only one year of information, while IFRS requires two years of data. Categorizing Transactions: IFRS is more flexible in where to present certain cash flow transactions than is US GAAP. This flexibility occurs around interest, dividends, and taxes. As shown in Table 16.1 , US GAAP is more rigid in reporting. Comparing GAAP and IFRS   US GAAP IFRS Interest paid Operating Operating or financing Interest received Operating Operating or investing Dividends paid Financing Operating or financing Dividends received Operating Operating or investing Taxes Operating Usually operating but option to dissect tax into operating and financing components Table 16.1 Understanding the impact of these potential differences is important. The statement of cash flows is used not only to evaluate from where a company receives and spends its cash, but also to predict future cash flows. The flexibility of these reporting items in the statement of cash flows can result in decreased comparability between similar companies using different reporting methods. For example, Free Cash Flow (Operating Cash Flows less Capital Expenditures), will have different results if interest and dividends are classified in sections other than operating activities. Let’s consider an example: World-Wide Co. is headquartered in London and currently reports under US GAAP because it is traded on the New York Stock Exchange (NYSE). World-Wide is considering switching to reporting under IFRS to make the company more comparable to its competitors, since most of them use IFRS. World-Wide has the following information in the operating activities section of its most recent statement of cash flows. World-Wide had $1,000,000 in capital expenditures during the year, and they paid dividends of $80,000 to shareholders. Based on this information, World-Wide’s Free Cash Flow would be as follows: or $2,500,000 − $1,000,000 = $1,500,000 If World-Wide switches to IFRS reporting, it has determined that its cash interest payments would be classified as financing activities because the payments are related to long-term debt. The interest received is from a short-term receivable and thus will remain classified as an operating activity, but the dividends received are from a long-term investment and will be reclassified to an investing activity. And, $60,000 of the taxes have been identified as being associated with tax consequences of an investing opportunity and therefore will be reclassified as an investing activity. With these reclassifications, the free cash flow of World-Wide would be as follows: FCF = ($2,500,000 + $200,000 − $50,000 + $60,000) − 1,000,000 = $1,710,000 The take-away from this example is that the flexibility afforded by IFRS can have an impact on comparability between companies. These, and other differences, between US GAAP and IFRS arise because of the more rules-based nature of the standards put forth by FASB versus the more principles-based rules set forth by IASB. The IASB, in creating IFRS standards, follows a substance-over-form viewpoint that allows firms more flexibility in assessing the intent of transactions. Anytime more judgement is allowed and/or utilized, there must be adequate disclosure to explain the chosen reporting methodology. 16.6 Appendix: Prepare a Completed Statement of Cash Flows Using the Direct Method As previously mentioned, the net cash flows for all sections of the statement of cash flows are identical when using the direct method or the indirect method. The difference is just in the way that net cash flows from operating activities are calculated and presented. The direct approach requires that each item of income and expense be converted from the accrual basis value to the cash basis value for that item. This is accomplished by adjusting the accrual amount for the revenue or expense by any related current operating asset or liability. Revenue and expense items that are not related to those current asset and liability accounts would not need an adjustment. In the following section, we demonstrate the calculations needed to assess the component pieces of the operating section using the direct approach. Cash Collected from Customers Cash collected from customers is different from the sales revenue that is recorded on the accrual basis financial statements. To reconcile the amount of sales revenue reported on the income statement to the cash collected from sales, calculate the maximum amount of cash that could have been collected this period (potential cash collected) by combining (a) the amount that was due from customers on the first day of the period (beginning accounts receivable) and (b) total sales revenue recorded this period. If there were no outstanding accounts receivable balance at the end of the period, then one could reasonably assume that this total was collected in full during this period. Thus, the amount collected for sales can be determined by subtracting the ending accounts receivable balance from the total potential cash that could have been collected. Cash Paid to Suppliers for Inventory Cash paid for inventory is different from the cost of goods sold that is recorded on the accrual basis financial statements. To reconcile the amount of cost of goods sold reported on the income statement to the cash paid for inventory, it is necessary to perform two calculations. The first part of the calculation determines how much inventory was purchased, and the second part of the calculation determines how much of those purchases were paid for during the current period. First, calculate the maximum amount of inventory that was available for sale this period by combining (a) the amount of inventory that was on hand on the last day of the period (ending inventory) and (b) total cost of goods sold recorded this period. If there were no inventory balance at the beginning of the period, then one could reasonably assume that this total was purchased entirely during the current period. Thus, the amount of inventory purchased this period can be determined by subtracting the beginning inventory balance from the total goods (inventory) available for sale. Second, calculate the maximum amount of cash that could have been paid for inventory this period (total obligation to pay inventory costs) by combining (a) the amount that was due to suppliers on the first day of the period (beginning accounts payable) and (b) total inventory purchases this period, from the first inventory calculation. If there were no outstanding accounts payable balance at the end of the period, then one could reasonably assume that this total was paid in full during this current period. Thus, the amount paid for inventory can be determined by subtracting the ending accounts payable balance from the total obligation to pay inventory costs that could have been paid. The final number of the second calculation is the actual cash paid for inventory. Cash Paid for Salaries Cash paid for salaries is different from the salaries expense that is recorded on the accrual basis financial statements. To reconcile the amount of salaries expense reported on the income statement to the cash paid for salaries, calculate the maximum amount of cash that could have been paid for salaries this period (total obligation to pay salaries) by combining (a) the amount that was due to employees on the first day of the period (beginning salaries payable) and (b) total salaries expense recorded this period. If there were no outstanding salaries payable balance at the end of the period, then one could reasonably assume that this total was paid in full during this current period. Thus, the amount paid for salaries can be determined by subtracting the ending salaries payable balance from the total obligation to pay salaries that could have been paid. Cash Paid for Insurance Cash paid for insurance is different from the insurance expense that is recorded on the accrual basis financial statements. To reconcile the amount of insurance expense reported on the income statement to the cash paid for insurance premiums, calculate the maximum amount of cash that could have been paid for insurance this period (total insurance premiums expended) by combining (a) the amount of insurance premiums that were prepaid on the last day of the period (ending prepaid insurance) and (b) total insurance expense recorded this period. If there were no prepaid insurance balance at the beginning of the period, then one could reasonably assume that this total was paid entirely during the current period. Thus, the amount paid for insurance this period can be determined by subtracting the beginning prepaid insurance balance from the total insurance premiums that had been recorded as expended.
american_government
Summary 8.1 What Is the Media? The media encompass all communications that transmit facts or information to citizens and includes the mass media in print and on the radio, television, and Internet. Television takes many forms, such as local, network, cable, or satellite. Historically, programming was transmitted from networks to local stations and broadcast via the airwaves, while fiber-optic cables now allow for national programming to transmit directly. Technological advances allow on-demand and streaming access for programming, leading to changes in advertising and scheduling practices. Conglomerates are large media corporations that own many stations and other companies; therefore, they can create a monopoly and decrease the flow of information to the public. The media serves to entertain the public, watch for corruption, set the national agenda, and promote the public good. In each of these roles, the media informs the public about what is happening and signals when citizens should act. 8.2 The Evolution of the Media Newspapers were vital during the Revolutionary War. Later, in the party press era, party loyalty governed coverage. At the turn of the twentieth century, investigative journalism and muckraking appeared, and newspapers began presenting more professional, unbiased information. The modern print media have fought to stay relevant and cost-efficient, moving online to do so. Most families had radios by the 1930s, making it an effective way for politicians, especially presidents, to reach out to citizens. While the increased use of television decreased the popularity of radio, talk radio still provides political information. Modern presidents also use television to rally people in times of crisis, although social media and the Internet now offer a more direct way for them to communicate. While serious newscasts still exist, younger viewers prefer soft news as a way to become informed. 8.3 Regulating the Media While freedom of the press is an important aspect of the Bill of Rights, this freedom is not absolute and may be regulated by the U.S. government. The press cannot libel or slander individuals or publish information about troop movements or undercover operatives. The Federal Communications Commission can enforce limits on television and radio programming by fining or revoking licenses. Broadcast material cannot be obscene, and indecent programs can be broadcast only between 10 p.m. and 6 a.m. Stations must also give political candidates equal time for advertising and interviews. The media help governments maintain transparency. Sunshine laws require some governments and government agencies to make meeting documents public. Some presidents have encouraged journalists and allowed questioning while others have avoided the press. Lack of openness by government officials leads journalists to use confidential sources for important or classified information. The Supreme Court does not give the press complete freedom to keep sources confidential, though the government can choose whom it prosecutes for hiding sources. 8.4 The Impact of the Media Writers began to formally study media bias in the 1920s. Initially, the press was seen as being able to place information in our minds, but later research found that the media have a minimal effect on recipients. A more recent theory is that the media cultivates our reality by presenting information that creates our perceptions of the world. The media does have the ability to frame what it presents, and it can also prime citizens to think a particular way, which changes how they react to new information. The media’s coverage of electoral candidates has increasingly become analysis rather than reporting. Sound bites from candidates are shorter. The press now provides horse-race coverage on the campaigns rather than in-depth coverage on candidates and their positions, forcing voters to look for other sources, like social media, for information. Current coverage of the government focuses more on what the president does than on presidential policies. Congress, on the other hand, is rarely affected by the media. Most topics discussed by the media are already being discussed by members of Congress or its committees. The media frame discussions and choose pictures, information, and video to support stories, which may affect the way people vote on social policy and in elections.
Chapter Outline 8.1 What Is the Media? 8.2 The Evolution of the Media 8.3 Regulating the Media 8.4 The Impact of the Media Introduction Democratic primary candidate Bernie Sanders arrived in Seattle on August 8, 2015, to give a speech at a rally to promote his presidential campaign. Instead, the rally was interrupted—and eventually co-opted—by activists for Black Lives Matter ( Figure 8.1 ). 1 Why did the group risk alienating Democratic voters by preventing Sanders from speaking? Because Black Lives Matter had been trying to raise awareness of the treatment of black citizens in the United States, and the media has the power to elevate such issues. 2 While some questioned its tactics, the organization’s move underscores how important the media are to gaining recognition, and the lengths to which organizations are willing to go to get media attention. 3 Freedom of the press and an independent media are important dimensions of a liberal society and a necessary part of a healthy democracy. “No government ought to be without censors,” said Thomas Jefferson, “and where the press is free, no one ever will.” 4 What does it mean to have a free news media? What regulations limit what media can do? How do the media contribute to informing citizens and monitoring politicians and the government, and how do we measure their impact? This chapter explores these and other questions about the role of the media in the United States.
[ { "answer": { "ans_choice": 0, "ans_text": "A" }, "bloom": null, "hl_context": "<hl> Most affiliate stations will show local news before and after network programming to inform local viewers of events and issues . <hl> Network news has a national focus on politics , international events , the economy , and more . Local news , on the other hand , is likely to focus on matters close to home , such as regional business , crime , sports , and weather . 5 The NBC Nightly News , for example , covers presidential campaigns and the White House or skirmishes between North Korea and South Korea , while the NBC affiliate in Los Angeles ( KNBC-TV ) and the NBC affiliate in Dallas ( KXAS-TV ) report on the governor ’ s activities or weekend festivals in the region .", "hl_sentences": "Most affiliate stations will show local news before and after network programming to inform local viewers of events and issues .", "question": { "cloze_format": "A local station that broadcasts national network programming is called a(an) ________ station.", "normal_format": "What is a local station that broadcasts national network programming is called?", "question_choices": [ "affiliate", "cable", "digital", "network" ], "question_id": "fs-id1171471003538", "question_text": "A local station that broadcasts national network programming is called a(an) ________ station." }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 1, "ans_text": "national" }, "bloom": null, "hl_context": "<hl> Cable programming offers national networks a second method to directly reach local viewers . <hl> As the name implies , cable stations transmit programming directly to a local cable company hub , which then sends the signals to homes through coaxial or fiber optic cables . Because cable does not broadcast programming through the airwaves , cable networks can operate across the nation directly without local affiliates . Instead they purchase broadcasting rights for the cable stations they believe their viewers want . For this reason , cable networks often specialize in different types of programming .", "hl_sentences": "Cable programming offers national networks a second method to directly reach local viewers .", "question": { "cloze_format": "Cable programming is often ________.", "normal_format": "Which of the following is correct about cable programming?", "question_choices": [ "local", "national", "network", "sports" ], "question_id": "fs-id1171471001885", "question_text": "Cable programming is often ________." }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 1, "ans_text": "B" }, "bloom": null, "hl_context": "Regardless of where we get our information , the various media avenues available today , versus years ago , make it much easier for everyone to be engaged . The question is : Who controls the media we rely on ? Most media are controlled by a limited number of conglomerates . <hl> A conglomerate is a corporation made up of a number of companies , organizations , and media networks . <hl> In the 1980s , more than fifty companies owned the majority of television and radio stations and networks . Now , only six conglomerates control most of the broadcast media in the United States : CBS Corporation , Comcast , Time Warner , 21st Century Fox ( formerly News Corporation ) , Viacom , and The Walt Disney Company ( Figure 8.3 ) . 8 The Walt Disney Company , for example , owns the ABC Television Network , ESPN , A & E , and Lifetime , in addition to the Disney Channel . Viacom owns BET , Comedy Central , MTV , Nickelodeon , and VH1 . Time Warner owns Cartoon Network , CNN , HBO , and TNT , among others . While each of these networks has its own programming , in the end , the conglomerate can make a policy that affects all stations and programming under its control .", "hl_sentences": "A conglomerate is a corporation made up of a number of companies , organizations , and media networks .", "question": { "cloze_format": "A conglomerate is a corporation that ________.", "normal_format": "What does a conglomerate that is a corporation do?", "question_choices": [ "owns all television news stations in a state", "owns many businesses and media networks", "owns only radio stations", "owns only televisions and newspapers" ], "question_id": "fs-id1171471311955", "question_text": "A conglomerate is a corporation that ________." }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 0, "ans_text": "decides which issues deserve public attention" }, "bloom": null, "hl_context": "<hl> The media also engages in agenda setting , which is the act of choosing which issues or topics deserve public discussion . <hl> For example , in the early 1980s , famine in Ethiopia drew worldwide attention , which resulted in increased charitable giving to the country . Yet the famine had been going on for a long time before it was discovered by western media . Even after the discovery , it took video footage to gain the attention of the British and U . S . populations and start the aid flowing . 12 Today , numerous examples of agenda setting show how important the media are when trying to prevent further emergencies or humanitarian crises . In the spring of 2015 , when the Dominican Republic was preparing to exile Haitians and undocumented ( or under documented ) residents , major U . S . news outlets remained silent . However , once the story had been covered several times by Al Jazeera , a state-funded broadcast company based in Qatar , ABC , the New York Times , and other network outlets followed . 13 With major network coverage came public pressure for the U . S . government to act on behalf of the Haitians . 14", "hl_sentences": "The media also engages in agenda setting , which is the act of choosing which issues or topics deserve public discussion .", "question": { "cloze_format": "When acting as an agenda setter, the media ________.", "normal_format": "When acting as an agenda setter, what does the media do?", "question_choices": [ "decides which issues deserve public attention", "covers presidential campaigns equally", "reports on corruption in government", "brings in advertising revenue for the media corporation" ], "question_id": "fs-id1171470824784", "question_text": "When acting as an agenda setter, the media ________." }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 1, "ans_text": "unite the colonists and provide information about the British" }, "bloom": null, "hl_context": "<hl> Although newspapers united for a common cause during the Revolutionary War , the divisions that occurred during the Constitutional Convention and the United States ’ early history created a change . <hl> The publication of the Federalist Papers , as well as the Anti-Federalist Papers , in the 1780s , moved the nation into the party press era , in which partisanship and political party loyalty dominated the choice of editorial content . One reason was cost . Subscriptions and advertisements did not fully cover printing costs , and political parties stepped in to support presses that aided the parties and their policies . Papers began printing party propaganda and messages , even publicly attacking political leaders like George Washington . Despite the antagonism of the press , Washington and several other founders felt that freedom of the press was important for creating an informed electorate . Indeed , freedom of the press is enshrined in the Bill of Rights in the first amendment . Early news was presented to local populations through the print press . While several colonies had printers and occasional newspapers , high literacy rates combined with the desire for self-government made Boston a perfect location for the creation of a newspaper , and the first continuous press was started there in 1704 . 21 Newspapers spread information about local events and activities . The Stamp Tax of 1765 raised costs for publishers , however , leading several newspapers to fold under the increased cost of paper . <hl> The repeal of the Stamp Tax in 1766 quieted concerns for a short while , but editors and writers soon began questioning the right of the British to rule over the colonies . <hl> <hl> Newspapers took part in the effort to inform citizens of British misdeeds and incite attempts to revolt . <hl> Readership across the colonies increased to nearly forty thousand homes ( among a total population of two million ) , and daily papers sprang up in large cities . 22", "hl_sentences": "Although newspapers united for a common cause during the Revolutionary War , the divisions that occurred during the Constitutional Convention and the United States ’ early history created a change . The repeal of the Stamp Tax in 1766 quieted concerns for a short while , but editors and writers soon began questioning the right of the British to rule over the colonies . Newspapers took part in the effort to inform citizens of British misdeeds and incite attempts to revolt .", "question": { "cloze_format": "Newspapers during the Revolutionary War period tended to ________.", "normal_format": "What did newspapers during the Revolutionary War period tend to?", "question_choices": [ "give fake news and sensationalize stories", "unite the colonists and provide information about the British", "print party propaganda", "attack colonial politicians" ], "question_id": "fs-id1171472123393", "question_text": "Newspapers during the Revolutionary War period tended to ________." }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 0, "ans_text": "A" }, "bloom": null, "hl_context": "In 1896 , Adolph Ochs purchased the New York Times with the goal of creating a dignified newspaper that would provide readers with important news about the economy , politics , and the world rather than gossip and comics . The New York Times brought back the informational model , which exhibits impartiality and accuracy and promotes transparency in government and politics . <hl> With the arrival of the Progressive Era , the media began muckraking : the writing and publishing of news coverage that exposed corrupt business and government practices . <hl> Investigative work like Upton Sinclair ’ s serialized novel The Jungle led to changes in the way industrial workers were treated and local political machines were run . The Pure Food and Drug Act and other laws were passed to protect consumers and employees from unsafe food processing practices . Local and state government officials who participated in bribery and corruption became the centerpieces of exposés .", "hl_sentences": "With the arrival of the Progressive Era , the media began muckraking : the writing and publishing of news coverage that exposed corrupt business and government practices .", "question": { "cloze_format": "Muckraking occurs when newspapers ________.", "normal_format": "Muckraking occurs when newspapers what?", "question_choices": [ "investigate problems in government and business", "investigate actions of celebrities", "print sensational news on the front page to sell papers", "print more editorials and opinion pieces to sell papers" ], "question_id": "fs-id1171472276931", "question_text": "Muckraking occurs when newspapers ________." }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 3, "ans_text": "1990s" }, "bloom": null, "hl_context": "Prior to WWII , radio frequencies were broadcast using amplitude modulation ( AM ) . After WWII , frequency modulation ( FM ) broadcasting , with its wider signal bandwidth , provided clear sound with less static and became popular with stations wanting to broadcast speeches or music with high-quality sound . While radio ’ s importance for distributing news waned with the increase in television usage , it remained popular for listening to music , educational talk shows , and sports broadcasting . Talk stations began to gain ground in the 1980s on both AM and FM frequencies , restoring radio ’ s importance in politics . <hl> By the 1990s , talk shows had gone national , showcasing broadcasters like Rush Limbaugh and Don Imus . <hl>", "hl_sentences": "By the 1990s , talk shows had gone national , showcasing broadcasters like Rush Limbaugh and Don Imus .", "question": { "cloze_format": "Radio quiz shows and comedy shows were most popular in the ________.", "normal_format": "When were radio quiz shows and comedy shows most popular?", "question_choices": [ "1900s", "1930s", "1970s", "1990s" ], "question_id": "fs-id1171472275099", "question_text": "Radio quiz shows and comedy shows were most popular in the ________." }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 2, "ans_text": "C" }, "bloom": null, "hl_context": "Television combined the best attributes of radio and pictures and changed media forever . The first official broadcast in the United States was President Franklin Roosevelt ’ s speech at the opening of the 1939 World ’ s Fair in New York . <hl> The public did not immediately begin buying televisions , but coverage of World War II changed their minds . <hl> <hl> CBS reported on war events and included pictures and maps that enhanced the news for viewers . <hl> By the 1950s , the price of television sets had dropped , more televisions stations were being created , and advertisers were buying up spots .", "hl_sentences": "The public did not immediately begin buying televisions , but coverage of World War II changed their minds . CBS reported on war events and included pictures and maps that enhanced the news for viewers .", "question": { "cloze_format": "Television news became a regular feature during ________ due to the public’s demand for ________ to explain current events.", "normal_format": "When did Television news become a regular feature, and what demand caused that?", "question_choices": [ "WWI; images and maps", "Great Depression; charts and tables", "WWII; images and maps", "Vietnam War; charts and tables" ], "question_id": "fs-id1171472124693", "question_text": "Television news became a regular feature during ________ due to the public’s demand for ________ to explain current events." }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 0, "ans_text": "A" }, "bloom": null, "hl_context": "A private individual must make one of the above arguments or argue that the author was negligent in not making sure the information was accurate before publishing it . For this reason , newspapers and magazines are less likely to stray from hard facts when covering private individuals , yet they can be willing to stretch the facts when writing about politicians , celebrities , or public figures . But even stretching the truth can be costly for a publisher . <hl> In 2010 , Star magazine published a headline , “ Addiction Nightmare : Katie Drug Shocker , ” leading readers to believe actress Katie Holmes was taking drugs . <hl> <hl> While the article in the magazine focuses on the addictive quality of Scientology sessions rather than drugs , the implication and the headline were different . <hl> <hl> Because drugs cause people to act erratically , directors might be less inclined to hire Holmes if she were addicted to drugs . <hl> <hl> Thus Holmes could argue that she had lost opportunity and income from the headline . <hl> <hl> While the publisher initially declined to correct the story , Holmes filed a $ 50 million lawsuit , and Star ’ s parent company American Media , Inc . eventually settled . <hl> Star printed an apology and made a donation to a charity on Holmes ’ behalf . 65", "hl_sentences": "In 2010 , Star magazine published a headline , “ Addiction Nightmare : Katie Drug Shocker , ” leading readers to believe actress Katie Holmes was taking drugs . While the article in the magazine focuses on the addictive quality of Scientology sessions rather than drugs , the implication and the headline were different . Because drugs cause people to act erratically , directors might be less inclined to hire Holmes if she were addicted to drugs . Thus Holmes could argue that she had lost opportunity and income from the headline . While the publisher initially declined to correct the story , Holmes filed a $ 50 million lawsuit , and Star ’ s parent company American Media , Inc . eventually settled .", "question": { "cloze_format": "The circumstance in which the courts would find libel is when ___ .", "normal_format": "In which circumstance would the courts find libel?", "question_choices": [ "A reporter uses a source that incorrectly states a celebrity is using drugs.", "A columnist writes his opinion about whether an actor is hiding a drug problem.", "A television reporter delivers a story about increased drug use at the local college.", "A reporter writes that local college students are drug dealers but has no sources." ], "question_id": "fs-id1171474433092", "question_text": "In which circumstance would the courts find libel?" }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 1, "ans_text": "is partial, and the press may print classified material only if it does not compromise troops or covert operatives" }, "bloom": null, "hl_context": "The line between the people ’ s right to know and national security is not always clear . In 1971 , the Supreme Court heard the Pentagon Papers case , in which the U . S . government sued the New York Times and the Washington Post to stop the release of information from a classified study of the Vietnam War . <hl> The Supreme Court ruled that while the government can impose prior restraint on the media , meaning the government can prevent the publication of information , that right is very limited . <hl> <hl> The court gave the newspapers the right to publish much of the study , but revelation of troop movements and the names of undercover operatives are some of the few approved reasons for which the government can stop publication or reporting . <hl>", "hl_sentences": "The Supreme Court ruled that while the government can impose prior restraint on the media , meaning the government can prevent the publication of information , that right is very limited . The court gave the newspapers the right to publish much of the study , but revelation of troop movements and the names of undercover operatives are some of the few approved reasons for which the government can stop publication or reporting .", "question": { "cloze_format": "The Supreme Court determined that the right of the press to print classified material ________.", "normal_format": "What did the the Supreme Court determine that is the right of the press to print classified material?", "question_choices": [ "is obsolete, and the press may never print classified material", "is partial, and the press may print classified material only if it does not compromise troops or covert operatives", "is complete, and the press may print anything it likes", "has not yet been defined" ], "question_id": "fs-id1171474427002", "question_text": "The Supreme Court determined that the right of the press to print classified material ________." }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 3, "ans_text": "D" }, "bloom": null, "hl_context": "<hl> The Telecommunications Act of 1996 brought significant changes to the radio and television industries . <hl> It dropped the limit on the number of radio stations ( forty ) and television stations ( twelve ) a single company could own . <hl> It also allowed networks to purchase large numbers of cable stations . <hl> In essence , it reduced competition and increased the number of conglomerates . Some critics , such as Common Cause , argue that the act also raised cable prices and made it easier for companies to neglect their public interest obligations . <hl> 84 The act also changed the role of the FCC from regulator to monitor . <hl> The Commission oversees the purchase of stations to avoid media monopolies and adjudicates consumer complaints against radio , television , and telephone companies . <hl> The Communications Act of 1934 replaced the Radio Act and created a more powerful entity to monitor the airwaves — a seven-member Federal Communications Commission ( FCC ) to oversee both radio and telephone communication . <hl> The FCC , which now has only five members ( Figure 8.13 ) , requires radio stations to apply for licenses , granted only if stations follow rules about limiting advertising , providing a public forum for discussion , and serving local and minority communities . <hl> With the advent of television , the FCC was given the same authority to license and monitor television stations . <hl> The FCC now also enforces ownership limits to avoid monopolies and censors materials deemed inappropriate . It has no jurisdiction over print media , mainly because print media are purchased and not broadcast . <hl> In 1990 , Sirius Satellite Radio began a campaign for FCC approval of satellite radio . <hl> <hl> The idea was to broadcast digital programming from satellites in orbit , eliminating the need for local towers . <hl> <hl> By 2001 , two satellite stations had been approved for broadcasting . <hl> Satellite radio has greatly increased programming with many specialized offerings , such as channels dedicated to particular artists . It is generally subscription-based and offers a larger area of coverage , even to remote areas such as deserts and oceans . Satellite programming is also exempt from many of the FCC regulations that govern regular radio stations . Howard Stern , for example , was fined more than $ 2 million while on public airwaves , mainly for his sexually explicit discussions . 35 Stern moved to Sirius Satellite in 2006 and has since been free of oversight and fines .", "hl_sentences": "The Telecommunications Act of 1996 brought significant changes to the radio and television industries . It also allowed networks to purchase large numbers of cable stations . 84 The act also changed the role of the FCC from regulator to monitor . The Communications Act of 1934 replaced the Radio Act and created a more powerful entity to monitor the airwaves — a seven-member Federal Communications Commission ( FCC ) to oversee both radio and telephone communication . With the advent of television , the FCC was given the same authority to license and monitor television stations . In 1990 , Sirius Satellite Radio began a campaign for FCC approval of satellite radio . The idea was to broadcast digital programming from satellites in orbit , eliminating the need for local towers . By 2001 , two satellite stations had been approved for broadcasting .", "question": { "cloze_format": "The Federal Communications Commission oversees the programming of the entities ___ .", "normal_format": "The Federal Communications Commission oversees the programming of which entities?", "question_choices": [ "television", "television and radio", "television, radio, and satellite", "television, radio, satellite, and cable" ], "question_id": "fs-id1171472254444", "question_text": "The Federal Communications Commission oversees the programming of which entities?" }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 0, "ans_text": "medical records for government employees" }, "bloom": null, "hl_context": "While some documents may be classified due to national or state security , governments are encouraged to limit the over-classification of documents . <hl> The primary legal example for sunshine laws is the Freedom of Information Act ( FOIA ) , passed in 1966 and signed by President Lyndon B . Johnson . <hl> The act requires the executive branch of the U . S . government to provide information requested by citizens and was intended to increase openness in the executive branch , which had been criticized for hiding information . Citizens wishing to obtain information may request documents from the appropriate agencies , and agencies may charge fees if the collection and copying of the requested documentation requires time and labor . <hl> 89 FOIA also identifies data that does not need to be disclosed , such as human resource and medical records , national defense records , and material provided by confidential sources , to name a few . <hl> 90 Not all presidents have embraced this openness , however . President Ronald Reagan , in 1981 , exempted the CIA and FBI from FOIA requests . 91 Information requests have increased significantly in recent years , with U . S . agencies receiving over 700,000 requests in 2014 , many directed to the Departments of State and Defense , thus creating a backlog . 92", "hl_sentences": "The primary legal example for sunshine laws is the Freedom of Information Act ( FOIA ) , passed in 1966 and signed by President Lyndon B . Johnson . 89 FOIA also identifies data that does not need to be disclosed , such as human resource and medical records , national defense records , and material provided by confidential sources , to name a few .", "question": { "cloze_format": "___ is a reasonable exception to the Freedom of Information Act.", "normal_format": "Which of the following is a reasonable exception to the Freedom of Information Act?", "question_choices": [ "medical records for government employees", "budget for the Department of Labor", "minutes from a president’s cabinet meeting", "transcript of meetings between Department of State negotiators and Russian trade negotiators" ], "question_id": "fs-id1171474408484", "question_text": "Which of the following is a reasonable exception to the Freedom of Information Act?" }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 0, "ans_text": "A" }, "bloom": null, "hl_context": "<hl> Episodic framing occurs when a story focuses on isolated details or specifics rather than looking broadly at a whole issue . <hl> Thematic framing takes a broad look at an issue and skips numbers or details . It looks at how the issue has changed over a long period of time and what has led to it . <hl> For example , a large , urban city is dealing with the problem of an increasing homeless population , and the city has suggested ways to improve the situation . <hl> <hl> If journalists focus on the immediate statistics , report the current percentage of homeless people , interview a few , and look at the city ’ s current investment in a homeless shelter , the coverage is episodic . <hl> If they look at homelessness as a problem increasing everywhere , examine the reasons people become homeless , and discuss the trends in cities ’ attempts to solve the problem , the coverage is thematic . Episodic frames may create more sympathy , while a thematic frame may leave the reader or viewer emotionally disconnected and less sympathetic ( Figure 8.16 ) .", "hl_sentences": "Episodic framing occurs when a story focuses on isolated details or specifics rather than looking broadly at a whole issue . For example , a large , urban city is dealing with the problem of an increasing homeless population , and the city has suggested ways to improve the situation . If journalists focus on the immediate statistics , report the current percentage of homeless people , interview a few , and look at the city ’ s current investment in a homeless shelter , the coverage is episodic .", "question": { "cloze_format": "___ is an example of episodic framing.", "normal_format": "Which of the following is an example of episodic framing?", "question_choices": [ "a story on drug abuse that interviews addicts and discusses reasons for addiction and government responses to help addicts", "a story on how drug abuse policy has changed since 1984", "a story on candidates’ answers to a drug question in a debate", "a story detailing arguments against needle exchange programs" ], "question_id": "fs-id1171474414662", "question_text": "Which of the following is an example of episodic framing?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 2, "ans_text": "She fears the media will criticize her family." }, "bloom": null, "hl_context": "The historically negative media coverage of female candidates has had another concrete effect : Women are less likely than men to run for office . <hl> One common reason is the effect negative media coverage has on families . <hl> <hl> 144 Many women do not wish to expose their children or spouses to criticism . <hl> 145 In 2008 , the nomination of Sarah Palin as Republican candidate John McCain ’ s running mate validated this concern ( Figure 8.19 ) . Some articles focused on her qualifications to be a potential future president or her record on the issues . But others questioned whether she had the right to run for office , given she had young children , one of whom has developmental disabilities . 146 Her daughter , Bristol , was criticized for becoming pregnant while unmarried . 147 Her husband was called cheap for failing to buy her a high-priced wedding ring . 148 Even when candidates ask that children and families be off-limits , the press rarely honors the requests . So women with young children may wait until their children are grown before running for office , if they choose to run at all .", "hl_sentences": "One common reason is the effect negative media coverage has on families . 144 Many women do not wish to expose their children or spouses to criticism .", "question": { "cloze_format": "According to research, a woman might decide not to run for office because ___.", "normal_format": "According to research, why might a woman decide not to run for office?", "question_choices": [ "She feels the work is too hard.", "She fears her positions will be covered too closely by the press.", "She fears the media will criticize her family.", "She fears the campaign will be too expensive." ], "question_id": "fs-id1171474464746", "question_text": "According to research, why might a woman decide not to run for office?" }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 3, "ans_text": "D" }, "bloom": null, "hl_context": "Network news similarly misrepresents the victims of poverty by using more images of blacks than whites in its segments . Viewers in a study were left believing African Americans were the majority of the unemployed and poor , rather than seeing the problem as one faced by many races . 129 The misrepresentation of race is not limited to news coverage , however . <hl> A study of images printed in national magazines , like Time and Newsweek , found they also misrepresented race and poverty . <hl> <hl> The magazines were more likely to show images of young African Americans when discussing poverty and excluded the elderly and the young , as well as whites and Latinos , which is the true picture of poverty . <hl> 130", "hl_sentences": "A study of images printed in national magazines , like Time and Newsweek , found they also misrepresented race and poverty . The magazines were more likely to show images of young African Americans when discussing poverty and excluded the elderly and the young , as well as whites and Latinos , which is the true picture of poverty .", "question": { "cloze_format": "Media coverage of a race tends to ________.", "normal_format": "What does media coverage of a race tend to do?", "question_choices": [ "accurately portray all races equally", "accurately portray whites and blacks as victims", "overrepresent whites and the elderly as poor", "overrepresent African Americans as poor" ], "question_id": "fs-id1171472157755", "question_text": "Media coverage of a race tends to ________." }, "references_are_paraphrase": 0 } ]
8
8.1 What Is the Media? Learning Objectives By the end of this section, you will be able to: Explain what the media are and how they are organized Describe the main functions of the media in a free society Compare different media formats and their respective audiences Ours is an exploding media system. What started as print journalism was subsequently supplemented by radio coverage, then network television, followed by cable television. Now, with the addition of the Internet, blogs and social media—a set of applications or web platforms that allow users to immediately communicate with one another—give citizens a wide variety of sources for instant news of all kinds. The Internet also allows citizens to initiate public discussion by uploading images and video for viewing, such as videos documenting interactions between citizens and the police, for example. Provided we are connected digitally, we have a bewildering amount of choices for finding information about the world. In fact, some might say that compared to the tranquil days of the 1970s, when we might read the morning newspaper over breakfast and take in the network news at night, there are now too many choices in today’s increasingly complex world of information. This reality may make the news media all the more important to structuring and shaping narratives about U.S. politics. Or the proliferation of competing information sources like blogs and social media may actually weaken the power of the news media relative to the days when news media monopolized our attention. MEDIA BASICS The term media defines a number of different communication formats from television media, which share information through broadcast airwaves, to print media, which rely on printed documents. The collection of all forms of media that communicate information to the general public is called mass media , including television, print, radio, and Internet. One of the primary reasons citizens turn to the media is for news. We expect the media to cover important political and social events and information in a concise and neutral manner. To accomplish its work, the media employs a number of people in varied positions. Journalists and reporters are responsible for uncovering news stories by keeping an eye on areas of public interest, like politics, business, and sports. Once a journalist has a lead or a possible idea for a story, he or she researches background information and interviews people to create a complete and balanced account. Editors work in the background of the newsroom, assigning stories, approving articles or packages, and editing content for accuracy and clarity. Publishers are people or companies that own and produce print or digital media. They oversee both the content and finances of the publication, ensuring the organization turns a profit and creates a high-quality product to distribute to consumers. Producers oversee the production and finances of visual media, like television, radio, and film. The work of the news media differs from public relations , which is communication carried out to improve the image of companies, organizations, or candidates for office. Public relations is not a neutral information form. While journalists write stories to inform the public, a public relations spokesperson is paid to help an individual or organization get positive press. Public relations materials normally appear as press releases or paid advertisements in newspapers and other media outlets. Some less reputable publications, however, publish paid articles under the news banner, blurring the line between journalism and public relations. MEDIA TYPES Each form of media has its own complexities and is used by different demographics. Millennials (currently aged 21–37) are more likely to get news and information from social media, such as YouTube, Twitter, and Facebook, while Baby Boomers (currently aged 54–72) are most likely to get their news from television, either national broadcasts or local news ( Figure 8.2 ). Television alone offers viewers a variety of formats. Programming may be scripted, like dramas or comedies. It may be unscripted, like game shows or reality programs, or informative, such as news programming. Although most programs are created by a television production company, national networks—like CBS or NBC—purchase the rights to programs they distribute to local stations across the United States. Most local stations are affiliated with a national network corporation, and they broadcast national network programming to their local viewers. Before the existence of cable and fiber optics, networks needed to own local affiliates to have access to the local station’s transmission towers. Towers have a limited radius, so each network needed an affiliate in each major city to reach viewers. While cable technology has lessened networks’ dependence on aerial signals, some viewers still use antennas and receivers to view programming broadcast from local towers. Affiliates, by agreement with the networks, give priority to network news and other programming chosen by the affiliate’s national media corporation. Local affiliate stations are told when to air programs or commercials, and they diverge only to inform the public about a local or national emergency. For example, ABC affiliates broadcast the popular television show Once Upon a Time at a specific time on a specific day. Should a fire threaten homes and businesses in a local area, the affiliate might preempt it to update citizens on the fire’s dangers and return to regularly scheduled programming after the danger has ended. Most affiliate stations will show local news before and after network programming to inform local viewers of events and issues. Network news has a national focus on politics, international events, the economy, and more. Local news, on the other hand, is likely to focus on matters close to home, such as regional business, crime, sports, and weather. 5 The NBC Nightly News , for example, covers presidential campaigns and the White House or skirmishes between North Korea and South Korea, while the NBC affiliate in Los Angeles (KNBC-TV) and the NBC affiliate in Dallas (KXAS-TV) report on the governor’s activities or weekend festivals in the region. Cable programming offers national networks a second method to directly reach local viewers. As the name implies, cable stations transmit programming directly to a local cable company hub, which then sends the signals to homes through coaxial or fiber optic cables. Because cable does not broadcast programming through the airwaves, cable networks can operate across the nation directly without local affiliates. Instead they purchase broadcasting rights for the cable stations they believe their viewers want. For this reason, cable networks often specialize in different types of programming. The Cable News Network (CNN) was the first news station to take advantage of this specialized format, creating a 24-hour news station with live coverage and interview programs. Other news stations quickly followed, such as MSNBC and FOX News. A viewer might tune in to Nickelodeon and catch family programs and movies or watch ESPN to catch up with the latest baseball or basketball scores. The Cable-Satellite Public Affairs Network, known better as C-SPAN, now has three channels covering Congress, the president, the courts, and matters of public interest. Cable and satellite providers also offer on-demand programming for most stations. Citizens can purchase cable, satellite, and Internet subscription services (like Netflix) to find programs to watch instantly, without being tied to a schedule. Initially, on-demand programming was limited to rebroadcasting old content and was commercial-free. Yet many networks and programs now allow their new programming to be aired within a day or two of its initial broadcast. In return they often add commercials the user cannot fast-forward or avoid. Thus networks expect advertising revenues to increase. 6 The on-demand nature of the Internet has created many opportunities for news outlets. While early media providers were those who could pay the high cost of printing or broadcasting, modern media require just a URL and ample server space. The ease of online publication has made it possible for more niche media outlets to form. The websites of the New York Times and other newspapers often focus on matters affecting the United States, while channels like BBC America present world news. FOX News presents political commentary and news in a conservative vein, while the Internet site Daily Kos offers a liberal perspective on the news. Politico.com is perhaps the leader in niche journalism. Unfortunately, the proliferation of online news has also increased the amount of poorly written material with little editorial oversight, and readers must be cautious when reading Internet news sources. Sites like Buzzfeed allow members to post articles without review by an editorial board, leading to articles of varied quality and accuracy. The Internet has also made publication speed a consideration for professional journalists. No news outlet wants to be the last to break a story, and the rush to publication often leads to typographical and factual errors. Even large news outlets, like the Associated Press, have published articles with errors in their haste to get a story out. The Internet also facilitates the flow of information through social media, which allows users to instantly communicate with one another and share with audiences that can grow exponentially. Facebook and Twitter have millions of daily users. Social media changes more rapidly than the other media formats. While people in many different age groups use sites like Facebook, Twitter, and YouTube, other sites like Snapchat and Yik Yak appeal mostly to younger users. The platforms also serve different functions. Tumblr and Reddit facilitate discussion that is topic-based and controversial, while Instagram is mostly social. A growing number of these sites also allow users to comment anonymously, leading to increases in threats and abuse. The site 4chan, for example, was linked to the 2015 shooting at an Oregon community college. 7 Regardless of where we get our information, the various media avenues available today, versus years ago, make it much easier for everyone to be engaged. The question is: Who controls the media we rely on? Most media are controlled by a limited number of conglomerates. A conglomerate is a corporation made up of a number of companies, organizations, and media networks. In the 1980s, more than fifty companies owned the majority of television and radio stations and networks. Now, only six conglomerates control most of the broadcast media in the United States: CBS Corporation, Comcast, Time Warner, 21st Century Fox (formerly News Corporation), Viacom, and The Walt Disney Company ( Figure 8.3 ). 8 The Walt Disney Company, for example, owns the ABC Television Network, ESPN, A&E, and Lifetime, in addition to the Disney Channel. Viacom owns BET, Comedy Central, MTV, Nickelodeon, and VH1. Time Warner owns Cartoon Network, CNN, HBO, and TNT, among others. While each of these networks has its own programming, in the end, the conglomerate can make a policy that affects all stations and programming under its control. Conglomerates can create a monopoly on information by controlling a sector of a market. When a media conglomerate has policies or restrictions, they will apply to all stations or outlets under its ownership, potentially limiting the information citizens receive. Conglomerate ownership also creates circumstances in which censorship may occur. iHeartMedia (formerly Clear Channel Media) owns music, radio, and billboards throughout the United States, and in 2010, the company refused to run several billboard ads for the St. Pete Pride Festival and Promenade in St. Petersburg, Florida. The festival organizers said the content of two ads, a picture of same-sex couples in close contact with one another, was the reason the ads were not run. Because iHeartMedia owns most of the billboards in the area, this limitation was problematic for the festival and decreased awareness of the event. Those in charge of the festival viewed the refusal as censorship. 9 Newspapers too have experienced the pattern of concentrated ownership. Gannett Company, while also owning television media, holds a large number of newspapers and news magazines in its control. Many of these were acquired quietly, without public notice or discussion. Gannett’s 2013 acquisition of publishing giant A.H. Belo Corporation caused some concern and news coverage, however. The sale would have allowed Gannett to own both an NBC and a CBS affiliate in St. Louis, Missouri, giving it control over programming and advertising rates for two competing stations. The U.S. Department of Justice required Gannett to sell the station owned by Belo to ensure market competition and multi-ownership in St. Louis. 10 Link to Learning If you are concerned about the lack of variety in the media and the market dominance of media conglomerates, the non-profit organization, Free Press , tracks and promotes open communication. These changes in the format and ownership of media raise the question whether the media still operate as an independent source of information. Is it possible that corporations and CEOs now control the information flow, making profit more important than the impartial delivery of information? The reality is that media outlets, whether newspaper, television, radio, or Internet, are businesses. They have expenses and must raise revenues. Yet at the same time, we expect the media to entertain, inform, and alert us without bias. They must provide some public services, while following laws and regulations. Reconciling these goals may not always be possible. FUNCTIONS OF THE MEDIA The media exist to fill a number of functions. Whether the medium is a newspaper, a radio, or a television newscast, a corporation behind the scenes must bring in revenue and pay for the cost of the product. Revenue comes from advertising and sponsors, like McDonald’s, Ford Motor Company, and other large corporations. But corporations will not pay for advertising if there are no viewers or readers. So all programs and publications need to entertain, inform, or interest the public and maintain a steady stream of consumers. In the end, what attracts viewers and advertisers is what survives. The media are also watchdogs of society and of public officials. Some refer to the media as the fourth estate , with the branches of government being the first three estates and the media equally participating as the fourth. This role helps maintain democracy and keeps the government accountable for its actions, even if a branch of the government is reluctant to open itself to public scrutiny. As much as social scientists would like citizens to be informed and involved in politics and events, the reality is that we are not. So the media, especially journalists, keep an eye on what is happening and sounds an alarm when the public needs to pay attention. 11 The media also engages in agenda setting , which is the act of choosing which issues or topics deserve public discussion. For example, in the early 1980s, famine in Ethiopia drew worldwide attention, which resulted in increased charitable giving to the country. Yet the famine had been going on for a long time before it was discovered by western media. Even after the discovery, it took video footage to gain the attention of the British and U.S. populations and start the aid flowing. 12 Today, numerous examples of agenda setting show how important the media are when trying to prevent further emergencies or humanitarian crises. In the spring of 2015, when the Dominican Republic was preparing to exile Haitians and undocumented (or under documented) residents, major U.S. news outlets remained silent. However, once the story had been covered several times by Al Jazeera, a state-funded broadcast company based in Qatar, ABC, the New York Times , and other network outlets followed. 13 With major network coverage came public pressure for the U.S. government to act on behalf of the Haitians. 14 Insider Perspective Christiane Amanpour on “What Should Be News?” The media are our connection to the world. Some events are too big to ignore, yet other events, such as the destruction of Middle Eastern monuments or the plight of foreign refugees, are far enough from our shores that they often go unnoticed. What we see is carefully selected, but who decides what should be news? As the chief international correspondent for CNN, Christiane Amanpour is one media decision maker ( Figure 8.4 ). Over the years, Amanpour has covered events around the world from war to genocide. In an interview with Oprah Winfrey, Amanpour explains that her duty, and that of other journalists, is to make a difference in the world. To do that, “we have to educate people and use the media responsibly.” 15 Journalists cannot passively sit by and wait for stories to find them. “Words have consequences: the stories we decide to do, the stories we decide not to do . . . it all matters.” 16 As Amanpour points out, journalists are often “on the cutting edge of reform,” so if they fail to shed light on events, the results can be tragic. One of her biggest regrets was not covering the genocide in Rwanda in 1994, which cost nearly a million lives. She said the media ignored the event in favor of covering democratic elections in South Africa and a war in Bosnia, and ultimately she believes the media failed the people. “If we don’t respect our profession and we see it frittering away into the realm of triviality and sensationalism, we’ll lose our standing,” she said. “That won’t be good for democracy. A thriving society must have a thriving press.” This feeling of responsibility extends to covering moral topics, like genocide. Amanpour feels there shouldn’t be equal time given to all sides. “I’m not just a stenographer or someone with a megaphone; when I report, I have to do it in context, to be aware of the moral conundrum. . . . I have to be able to draw a line between victim and aggressor.” Amanpour also believes the media should cover more. When given the full background and details of events, society pays attention to the news. “Individual Americans had an incredible reaction to the [2004 Indian Ocean] tsunami—much faster than their government’s reaction,” she said. “Americans are a very moral and compassionate people who believe in extending a helping hand, especially when they get the full facts instead of one-minute clips.” If the news fulfills its responsibility, as she sees it, the world can show its compassion and help promote freedom. Why does Amanpour believe the press has a responsibility to report all that they see? Are there situations in which it is acceptable to display partiality in reporting the news? Why or why not? Before the Internet, traditional media determined whether citizen photographs or video footage would become “news.” In 1991, a private citizen’s camcorder footage showed four police officers beating an African American motorist named Rodney King in Los Angeles. After appearing on local independent television station, KTLA-TV, and then the national news, the event began a national discussion on police brutality and ignited riots in Los Angeles. 17 The agenda-setting power of traditional media has begun to be appropriated by social media and smartphones, however. Tumbler, Facebook, YouTube, and other Internet sites allow witnesses to instantly upload images and accounts of events and forward the link to friends. Some uploads go viral and attract the attention of the mainstream media, but large network newscasts and major newspapers are still more powerful at initiating or changing a discussion. The media also promote the public good by offering a platform for public debate and improving citizen awareness. Network news informs the electorate about national issues, elections, and international news. The New York Times , Los Angeles Times , NBC Nightly News , and other outlets make sure voters can easily find out what issues affect the nation. Is terrorism on the rise? Is the dollar weakening? The network news hosts national debates during presidential elections, broadcasts major presidential addresses, and interviews political leaders during times of crisis. Cable news networks now provide coverage of all these topics as well. Local news has a larger job, despite small budgets and fewer resources ( Figure 8.5 ). Local government and local economic policy have a strong and immediate effect on citizens. Is the city government planning on changing property tax rates? Will the school district change the way Common Core tests are administered? When and where is the next town hall meeting or public forum to be held? Local and social media provide a forum for protest and discussion of issues that matter to the community. Link to Learning Want a snapshot of local and state political and policy news? The magazine Governing keeps an eye on what is happening in each state, offering articles and analysis on events that occur across the country. While journalists reporting the news try to present information in an unbiased fashion, sometimes the public seeks opinion and analysis of complicated issues that affect various populations differently, like healthcare reform and the Affordable Care Act. This type of coverage may come in the form of editorials, commentaries, Op-Ed columns, and blogs. These forums allow the editorial staff and informed columnists to express a personal belief and attempt to persuade. If opinion writers are trusted by the public, they have influence. Walter Cronkite , reporting from Vietnam, had a loyal following. In a broadcast following the Tet Offensive in 1968, Cronkite expressed concern that the United States was mired in a conflict that would end in a stalemate. 18 His coverage was based on opinion after viewing the war from the ground. 19 Although the number of people supporting the war had dwindled by this time, Cronkite’s commentary bolstered opposition. Like editorials, commentaries contain opinion and are often written by specialists in a field. Larry Sabato, a prominent political science professor at the University of Virginia, occasionally writes his thoughts for the New York Times . These pieces are based on his expertise in politics and elections. 20 Blogs offer more personalized coverage, addressing specific concerns and perspectives for a limited group of readers. Nate Silver’s blog, FiveThirtyEight , focuses on elections and politics. 8.2 The Evolution of the Media Learning Objectives By the end of this section, you will be able to: Discuss the history of major media formats Compare important changes in media types over time Explain how citizens learn political information from the media The evolution of the media has been fraught with concerns and problems. Accusations of mind control, bias, and poor quality have been thrown at the media on a regular basis. Yet the growth of communications technology allows people today to find more information more easily than any previous generation. Mass media can be print, radio, television, or Internet news. They can be local, national, or international. They can be broad or limited in their focus. The choices are tremendous. PRINT MEDIA Early news was presented to local populations through the print press. While several colonies had printers and occasional newspapers, high literacy rates combined with the desire for self-government made Boston a perfect location for the creation of a newspaper, and the first continuous press was started there in 1704. 21 Newspapers spread information about local events and activities. The Stamp Tax of 1765 raised costs for publishers, however, leading several newspapers to fold under the increased cost of paper. The repeal of the Stamp Tax in 1766 quieted concerns for a short while, but editors and writers soon began questioning the right of the British to rule over the colonies. Newspapers took part in the effort to inform citizens of British misdeeds and incite attempts to revolt. Readership across the colonies increased to nearly forty thousand homes (among a total population of two million), and daily papers sprang up in large cities. 22 Although newspapers united for a common cause during the Revolutionary War, the divisions that occurred during the Constitutional Convention and the United States’ early history created a change. The publication of the Federalist Papers , as well as the Anti-Federalist Papers, in the 1780s, moved the nation into the party press era , in which partisanship and political party loyalty dominated the choice of editorial content. One reason was cost. Subscriptions and advertisements did not fully cover printing costs, and political parties stepped in to support presses that aided the parties and their policies. Papers began printing party propaganda and messages, even publicly attacking political leaders like George Washington. Despite the antagonism of the press, Washington and several other founders felt that freedom of the press was important for creating an informed electorate. Indeed, freedom of the press is enshrined in the Bill of Rights in the first amendment. Between 1830 and 1860, machines and manufacturing made the production of newspapers faster and less expensive. Benjamin Day’s paper, the New York Sun , used technology like the linotype machine to mass-produce papers ( Figure 8.6 ). Roads and waterways were expanded, decreasing the costs of distributing printed materials to subscribers. New newspapers popped up. The popular penny press papers and magazines contained more gossip than news, but they were affordable at a penny per issue. Over time, papers expanded their coverage to include racing, weather, and educational materials. By 1841, some news reporters considered themselves responsible for upholding high journalistic standards, and under the editor (and politician) Horace Greeley, the New-York Tribune became a nationally respected newspaper. By the end of the Civil War, more journalists and newspapers were aiming to meet professional standards of accuracy and impartiality. 23 Yet readers still wanted to be entertained. Joseph Pulitzer and the New York World gave them what they wanted. The tabloid-style paper included editorial pages, cartoons, and pictures, while the front-page news was sensational and scandalous. This style of coverage became known as yellow journalism . Ads sold quickly thanks to the paper’s popularity, and the Sunday edition became a regular feature of the newspaper. As the New York World’s circulation increased, other papers copied Pulitzer’s style in an effort to sell papers. Competition between newspapers led to increasingly sensationalized covers and crude issues. In 1896, Adolph Ochs purchased the New York Times with the goal of creating a dignified newspaper that would provide readers with important news about the economy, politics, and the world rather than gossip and comics. The New York Times brought back the informational model, which exhibits impartiality and accuracy and promotes transparency in government and politics. With the arrival of the Progressive Era, the media began muckraking : the writing and publishing of news coverage that exposed corrupt business and government practices. Investigative work like Upton Sinclair’s serialized novel The Jungle led to changes in the way industrial workers were treated and local political machines were run. The Pure Food and Drug Act and other laws were passed to protect consumers and employees from unsafe food processing practices. Local and state government officials who participated in bribery and corruption became the centerpieces of exposés. Some muckraking journalism still appears today, and the quicker movement of information through the system would seem to suggest an environment for yet more investigative work and the punch of exposés than in the past. However, at the same time there are fewer journalists being hired than there used to be. The scarcity of journalists and the lack of time to dig for details in a 24-hour, profit-oriented news model make investigative stories rare. 24 There are two potential concerns about the decline of investigative journalism in the digital age. First, one potential shortcoming is that the quality of news content will become uneven in depth and quality, which could lead to a less informed citizenry. Second, if investigative journalism in its systematic form declines, then the cases of wrongdoing that are the objects of such investigations would have a greater chance of going on undetected. In the twenty-first century, newspapers have struggled to stay financially stable. Print media earned $44.9 billion from ads in 2003, but only $16.4 billion from ads in 2014. 25 Given the countless alternate forms of news, many of which are free, newspaper subscriptions have fallen. Advertising and especially classified ad revenue dipped. Many newspapers now maintain both a print and an Internet presence in order to compete for readers. The rise of free news blogs, such as the Huffington Post , have made it difficult for newspapers to force readers to purchase online subscriptions to access material they place behind a digital paywall . Some local newspapers, in an effort to stay visible and profitable, have turned to social media, like Facebook and Twitter. Stories can be posted and retweeted, allowing readers to comment and forward material. 26 Yet, overall, newspapers have adapted, becoming leaner—though less thorough and investigative—versions of their earlier selves. RADIO Radio news made its appearance in the 1920s. The National Broadcasting Company (NBC) and the Columbia Broadcasting System (CBS) began running sponsored news programs and radio dramas. Comedy programs, such as Amos ’n’ Andy , The Adventures of Gracie , and Easy Aces , also became popular during the 1930s, as listeners were trying to find humor during the Depression ( Figure 8.7 ). Talk shows, religious shows, and educational programs followed, and by the late 1930s, game shows and quiz shows were added to the airwaves. Almost 83 percent of households had a radio by 1940, and most tuned in regularly. 27 Not just something to be enjoyed by those in the city, the proliferation of the radio brought communications to rural America as well. News and entertainment programs were also targeted to rural communities. WLS in Chicago provided the National Farm and Home Hour and the WLS Barn Dance . WSM in Nashville began to broadcast the live music show called the Grand Ole Opry , which is still broadcast every week and is the longest live broadcast radio show in U.S. history. 28 As radio listenership grew, politicians realized that the medium offered a way to reach the public in a personal manner. Warren Harding was the first president to regularly give speeches over the radio. President Herbert Hoover used radio as well, mainly to announce government programs on aid and unemployment relief. 29 Yet it was Franklin D. Roosevelt who became famous for harnessing the political power of radio. On entering office in March 1933, President Roosevelt needed to quiet public fears about the economy and prevent people from removing their money from the banks. He delivered his first radio speech eight days after assuming the presidency: “My friends: I want to talk for a few minutes with the people of the United States about banking—to talk with the comparatively few who understand the mechanics of banking, but more particularly with the overwhelming majority of you who use banks for the making of deposits and the drawing of checks. I want to tell you what has been done in the last few days, and why it was done, and what the next steps are going to be.” 30 Roosevelt spoke directly to the people and addressed them as equals. One listener described the chats as soothing, with the president acting like a father, sitting in the room with the family, cutting through the political nonsense and describing what help he needed from each family member. 31 Roosevelt would sit down and explain his ideas and actions directly to the people on a regular basis, confident that he could convince voters of their value. 32 His speeches became known as “ fireside chats ” and formed an important way for him to promote his New Deal agenda ( Figure 8.8 ). Roosevelt’s combination of persuasive rhetoric and the media allowed him to expand both the government and the presidency beyond their traditional roles. 33 During this time, print news still controlled much of the information flowing to the public. Radio news programs were limited in scope and number. But in the 1940s the German annexation of Austria, conflict in Europe, and World War II changed radio news forever. The need and desire for frequent news updates about the constantly evolving war made newspapers, with their once-a-day printing, too slow. People wanted to know what was happening, and they wanted to know immediately. Although initially reluctant to be on the air, reporter Edward R. Murrow of CBS began reporting live about Germany’s actions from his posts in Europe. His reporting contained news and some commentary, and even live coverage during Germany’s aerial bombing of London. To protect covert military operations during the war, the White House had placed guidelines on the reporting of classified information, making a legal exception to the First Amendment’s protection against government involvement in the press. Newscasters voluntarily agreed to suppress information, such as about the development of the atomic bomb and movements of the military, until after the events had occurred. 34 The number of professional and amateur radio stations grew quickly. Initially, the government exerted little legislative control over the industry. Stations chose their own broadcasting locations, signal strengths, and frequencies, which sometimes overlapped with one another or with the military, leading to tuning problems for listeners. The Radio Act (1927) created the Federal Radio Commission (FRC), which made the first effort to set standards, frequencies, and license stations. The Commission was under heavy pressure from Congress, however, and had little authority. The Communications Act of 1934 ended the FRC and created the Federal Communications Commission (FCC), which continued to work with radio stations to assign frequencies and set national standards, as well as oversee other forms of broadcasting and telephones. The FCC regulates interstate communications to this day. For example, it prohibits the use of certain profane words during certain hours on public airwaves. Prior to WWII, radio frequencies were broadcast using amplitude modulation (AM). After WWII, frequency modulation (FM) broadcasting, with its wider signal bandwidth, provided clear sound with less static and became popular with stations wanting to broadcast speeches or music with high-quality sound. While radio’s importance for distributing news waned with the increase in television usage, it remained popular for listening to music, educational talk shows, and sports broadcasting. Talk stations began to gain ground in the 1980s on both AM and FM frequencies, restoring radio’s importance in politics. By the 1990s, talk shows had gone national, showcasing broadcasters like Rush Limbaugh and Don Imus. In 1990, Sirius Satellite Radio began a campaign for FCC approval of satellite radio. The idea was to broadcast digital programming from satellites in orbit, eliminating the need for local towers. By 2001, two satellite stations had been approved for broadcasting. Satellite radio has greatly increased programming with many specialized offerings, such as channels dedicated to particular artists. It is generally subscription-based and offers a larger area of coverage, even to remote areas such as deserts and oceans. Satellite programming is also exempt from many of the FCC regulations that govern regular radio stations. Howard Stern, for example, was fined more than $2 million while on public airwaves, mainly for his sexually explicit discussions. 35 Stern moved to Sirius Satellite in 2006 and has since been free of oversight and fines. TELEVISION Television combined the best attributes of radio and pictures and changed media forever. The first official broadcast in the United States was President Franklin Roosevelt’s speech at the opening of the 1939 World’s Fair in New York. The public did not immediately begin buying televisions, but coverage of World War II changed their minds. CBS reported on war events and included pictures and maps that enhanced the news for viewers. By the 1950s, the price of television sets had dropped, more televisions stations were being created, and advertisers were buying up spots. As on the radio, quiz shows and games dominated the television airwaves. But when Edward R. Murrow made the move to television in 1951 with his news show See It Now , television journalism gained its foothold ( Figure 8.9 ). As television programming expanded, more channels were added. Networks such as ABC, CBS, and NBC began nightly newscasts, and local stations and affiliates followed suit. Even more than radio, television allows politicians to reach out and connect with citizens and voters in deeper ways. Before television, few voters were able to see a president or candidate speak or answer questions in an interview. Now everyone can decode body language and tone to decide whether candidates or politicians are sincere. Presidents can directly convey their anger, sorrow, or optimism during addresses. The first television advertisements, run by presidential candidates Dwight D. Eisenhower and Adlai Stevenson in the early 1950s, were mainly radio jingles with animation or short question-and-answer sessions. In 1960, John F. Kennedy ’s campaign used a Hollywood-style approach to promote his image as young and vibrant. The Kennedy campaign ran interesting and engaging ads, featuring Kennedy, his wife Jacqueline, and everyday citizens who supported him. Television was also useful to combat scandals and accusations of impropriety. Republican vice presidential candidate Richard Nixon used a televised speech in 1952 to address accusations that he had taken money from a political campaign fund illegally. Nixon laid out his finances, investments, and debts and ended by saying that the only election gift the family had received was a cocker spaniel the children named Checkers. 36 The “Checkers speech” was remembered more for humanizing Nixon than for proving he had not taken money from the campaign account. Yet it was enough to quiet accusations. Democratic vice presidential nominee Geraldine Ferraro similarly used television to answer accusations in 1984, holding a televised press conference to answer questions for over two hours about her husband’s business dealings and tax returns. 37 In addition to television ads, the 1960 election also featured the first televised presidential debate. By that time most households had a television. Kennedy’s careful grooming and practiced body language allowed viewers to focus on his presidential demeanor. His opponent, Richard Nixon, was still recovering from a severe case of the flu. While Nixon’s substantive answers and debate skills made a favorable impression on radio listeners, viewers’ reaction to his sweaty appearance and obvious discomfort demonstrated that live television had the potential to make or break a candidate. 38 In 1964, Lyndon B. Johnson was ahead in the polls, and he let Barry Goldwater’s campaign know he did not want to debate. 39 Nixon, who ran for president again in 1968 and 1972, declined to debate. Then in 1976, President Gerald Ford, who was behind in the polls, invited Jimmy Carter to debate, and televised debates became a regular part of future presidential campaigns. 40 Link to Learning Visit American Rhetoric for free access to speeches, video, and audio of famous presidential and political speeches. Between the 1960s and the 1990s, presidents often used television to reach citizens and gain support for policies. When they made speeches, the networks and their local affiliates carried them. With few independent local stations available, a viewer had little alternative but to watch. During this “Golden Age of Presidential Television,” presidents had a strong command of the media. 41 Some of the best examples of this power occurred when presidents used television to inspire and comfort the population during a national emergency. These speeches aided in the “rally ’round the flag” phenomenon, which occurs when a population feels threatened and unites around the president. 42 During these periods, presidents may receive heightened approval ratings, in part due to the media’s decision about what to cover. 43 In 1995, President Bill Clinton comforted and encouraged the families of the employees and children killed at the bombing of the Oklahoma City Federal Building. Clinton reminded the nation that children learn through action, and so we must speak up against violence and face evil acts with good acts. 44 Following the terrorist attacks in New York and Washington on September 11, 2001, President George W. Bush’s bullhorn speech from the rubble of Ground Zero in New York similarly became a rally. Bush spoke to the workers and first responders and encouraged them, but his short speech became a viral clip demonstrating the resilience of New Yorkers and the anger of a nation. 45 He told New Yorkers, the country, and the world that Americans could hear the frustration and anguish of New York, and that the terrorists would soon hear the United States ( Figure 8.10 ). Following their speeches, both presidents also received a bump in popularity. Clinton’s approval rating rose from 46 to 51 percent, and Bush’s from 51 to 90 percent. 46 NEW MEDIA TRENDS The invention of cable in the 1980s and the expansion of the Internet in the 2000s opened up more options for media consumers than ever before. Viewers can watch nearly anything at the click of a button, bypass commercials, and record programs of interest. The resulting saturation, or inundation of information, may lead viewers to abandon the news entirely or become more suspicious and fatigued about politics. 47 This effect, in turn, also changes the president’s ability to reach out to citizens. For example, viewership of the president’s annual State of the Union address has decreased over the years, from sixty-seven million viewers in 1993 to thirty-two million in 2015. 48 Citizens who want to watch reality television and movies can easily avoid the news, leaving presidents with no sure way to communicate with the public. 49 Other voices, such as those of talk show hosts and political pundits, now fill the gap. Electoral candidates have also lost some media ground. In horse-race coverage , modern journalists analyze campaigns and blunders or the overall race, rather than interviewing the candidates or discussing their issue positions. Some argue that this shallow coverage is a result of candidates’ trying to control the journalists by limiting interviews and quotes. In an effort to regain control of the story, journalists begin analyzing campaigns without input from the candidates. 50 The use of social media by candidates provides a countervailing trend. President Trump’s hundreds of election tweets are the stuff of legend. These tweets kept his press coverage up, although they also were problematic for him at times. The final days of the contest saw no new tweets from Trump as he attempted to stay on message. Milestone The First Social Media Candidate When president-elect Barack Obama admitted an addiction to his Blackberry, the signs were clear: A new generation was assuming the presidency. 51 Obama’s use of technology was a part of life, not a campaign pretense. Perhaps for this reason, he was the first candidate to fully embrace social media. While John McCain, the 2008 Republican presidential candidate, focused on traditional media to run his campaign, Obama did not. One of Obama’s campaign advisors was Chris Hughes, a cofounder of Facebook. The campaign allowed Hughes to create a powerful online presence for Obama, with sites on YouTube, Facebook, MySpace, and more. Podcasts and videos were available for anyone looking for information about the candidate. These efforts made it possible for information to be forwarded easily between friends and colleagues. It also allowed Obama to connect with a younger generation that was often left out of politics. By Election Day, Obama’s skill with the web was clear: he had over two million Facebook supporters, while McCain had 600,000. Obama had 112,000 followers on Twitter, and McCain had only 4,600. 52 Are there any disadvantages to a presidential candidate’s use of social media and the Internet for campaign purposes? Why or why not? The availability of the Internet and social media has moved some control of the message back into the presidents’ and candidates’ hands. Politicians can now connect to the people directly, bypassing journalists. When Barack Obama’s minister, the Reverend Jeremiah Wright, was accused of making inflammatory racial sermons in 2008, Obama used YouTube to respond to charges that he shared Wright’s beliefs. The video drew more than seven million views. 53 To reach out to supporters and voters, the White House maintains a YouTube channel and a Facebook site, as did the recent Republican Speaker of the House of Representatives, John Boehner. Social media, like Facebook, also placed journalism in the hands of citizens: citizen journalism occurs when citizens use their personal recording devices and cell phones to capture events and post them on the Internet. In 2012, citizen journalists caught both presidential candidates by surprise. Mitt Romney was taped by a bartender’s personal camera saying that 47 percent of Americans would vote for President Obama because they were dependent on the government. 54 Obama was recorded by a Huffington Post volunteer saying that some Midwesterners “cling to guns or religion or antipathy to people who aren’t like them” due to their frustration with the economy. 55 More recently, as Donald Trump was trying to close out the fall 2016 campaign, his musings about having his way with women were revealed on the infamous Billy Bush Access Hollywood tape. These statements became nightmares for the campaigns. As journalism continues to scale back and hire fewer professional writers in an effort to control costs, citizen journalism may become the new normal. 56 Another shift in the new media is a change in viewers’ preferred programming. Younger viewers, especially members of Generation X and Millennials, like their newscasts to be humorous. The popularity of The Daily Show and The Colbert Report demonstrate that news, even political news, can win young viewers if delivered well. 57 Such soft news presents news in an entertaining and approachable manner, painlessly introducing a variety of topics. While the depth or quality of reporting may be less than ideal, these shows can sound an alarm as needed to raise citizen awareness ( Figure 8.11 ). 58 Viewers who watch or listen to programs like John Oliver’s Last Week Tonight are more likely to be aware and observant of political events and foreign policy crises than they would otherwise be. 59 They may view opposing party candidates more favorably because the low-partisan, friendly interview styles allow politicians to relax and be conversational rather than defensive. 60 Because viewers of political comedy shows watch the news frequently, they may, in fact, be more politically knowledgeable than citizens viewing national news. In two studies researchers interviewed respondents and asked knowledge questions about current events and situations. Viewers of The Daily Show scored more correct answers than viewers of news programming and news stations. 61 That being said, it is not clear whether the number of viewers is large enough to make a big impact on politics, nor do we know whether the learning is long term or short term. 62 Get Connected! Becoming a Citizen Journalist Local government and politics need visibility. College students need a voice. Why not become a citizen journalist? City and county governments hold meetings on a regular basis and students rarely attend. Yet issues relevant to students are often discussed at these meetings, like increases in street parking fines, zoning for off-campus housing, and tax incentives for new businesses that employ part-time student labor. Attend some meetings, ask questions, and write about the experience on your Facebook page. Create a blog to organize your reports or use Storify to curate a social media debate. If you prefer videography, create a YouTube channel to document your reports on current events, or Tweet your live video using Periscope or Meerkat. Not interested in government? Other areas of governance that affect students are the university or college’s Board of Regents meetings. These cover topics like tuition increases, class cuts, and changes to student conduct policies. If your state requires state institutions to open their meetings to the public, consider attending. You might be the one to notify your peers of changes that affect them. What local meetings could you cover? What issues are important to you and your peers? 8.3 Regulating the Media Learning Objectives By the end of this section, you will be able to: Identify circumstances in which the freedom of the press is not absolute Compare the ways in which the government oversees and influences media programming The Constitution gives Congress responsibility for promoting the general welfare. While it is difficult to define what this broad dictate means, Congress has used it to protect citizens from media content it deems inappropriate. Although the media are independent participants in the U.S. political system, their liberties are not absolute and there are rules they must follow. MEDIA AND THE FIRST AMENDMENT The U.S. Constitution was written in secrecy. Journalists were neither invited to watch the drafting, nor did the framers talk to the press about their disagreements and decisions. Once it was finished, however, the Constitution was released to the public and almost all newspapers printed it. Newspaper editors also published commentary and opinion about the new document and the form of government it proposed. Early support for the Constitution was strong, and Anti-Federalists (who opposed it) argued that their concerns were not properly covered by the press. The eventual printing of The Federalist Papers , and the lesser-known Anti-Federalist Papers, fueled the argument that the press was vital to American democracy. It was also clear the press had the ability to affect public opinion and therefore public policy. 63 The approval of the First Amendment , as a part of the Bill of Rights, demonstrated the framers’ belief that a free and vital press was important enough to protect. It said: “Congress shall make no law respecting an establishment of religion, or prohibiting the free exercise thereof; or abridging the freedom of speech, or of the press; or the right of the people peaceably to assemble, and to petition the government for a redress of grievances.” This amendment serves as the basis for the political freedoms of the United States, and freedom of the press plays a strong role in keeping democracy healthy. Without it, the press would not be free to alert citizens to government abuses and corruption. In fact, one of New York’s first newspapers, the New York Weekly Journal , began under John Peter Zenger in 1733 with the goal of routing corruption in the colonial government. After the colonial governor, William Cosby, had Zenger arrested and charged with seditious libel in 1835, his lawyers successfully defended his case and Zenger was found not guilty, affirming the importance of a free press in the colonies ( Figure 8.12 ). The media act as informants and messengers, providing the means for citizens to become informed and serving as a venue for citizens to announce plans to assemble and protest actions by their government. Yet the government must ensure the media are acting in good faith and not abusing their power. Like the other First Amendment liberties, freedom of the press is not absolute. The media have limitations on their freedom to publish and broadcast. Slander and Libel First, the media do not have the right to commit slander , speak false information with an intent to harm a person or entity, or libel , print false information with an intent to harm a person or entity. These acts constitute defamation of character that can cause a loss of reputation and income. The media do not have the right to free speech in cases of libel and slander because the information is known to be false. Yet on a weekly basis, newspapers and magazines print stories that are negative and harmful. How can they do this and not be sued? First, libel and slander occur only in cases where false information is presented as fact. When editors or columnists write opinions, they are protected from many of the libel and slander provisions because they are not claiming their statements are facts. Second, it is up to the defamed individual or company to bring a lawsuit against the media outlet, and the courts have different standards depending on whether the claimant is a private or public figure. A public figure must show that the publisher or broadcaster acted in “reckless disregard” when submitting information as truth or that the author’s intent was malicious. This test goes back to the New York Times v. Sullivan (1964) case, in which a police commissioner in Alabama sued over inaccurate statements in a newspaper advertisement. 64 Because the commissioner was a public figure, the U.S. Supreme Court applied a stringent test of malice to determine whether the advertisement was libel; the court deemed it was not. A private individual must make one of the above arguments or argue that the author was negligent in not making sure the information was accurate before publishing it. For this reason, newspapers and magazines are less likely to stray from hard facts when covering private individuals, yet they can be willing to stretch the facts when writing about politicians, celebrities, or public figures. But even stretching the truth can be costly for a publisher. In 2010, Star magazine published a headline, “Addiction Nightmare: Katie Drug Shocker,” leading readers to believe actress Katie Holmes was taking drugs. While the article in the magazine focuses on the addictive quality of Scientology sessions rather than drugs, the implication and the headline were different. Because drugs cause people to act erratically, directors might be less inclined to hire Holmes if she were addicted to drugs. Thus Holmes could argue that she had lost opportunity and income from the headline. While the publisher initially declined to correct the story, Holmes filed a $50 million lawsuit, and Star’s parent company American Media, Inc. eventually settled. Star printed an apology and made a donation to a charity on Holmes’ behalf. 65 Classified Material The media have only a limited right to publish material the government says is classified. If a newspaper or media outlet obtains classified material, or if a journalist is witness to information that is classified, the government may request certain material be redacted or removed from the article. In many instances, government officials and former employees give journalists classified paperwork in an effort to bring public awareness to a problem. If the journalist calls the White House or Pentagon for quotations on a classified topic, the president may order the newspaper to stop publication in the interest of national security. The courts are then asked to rule on what is censored and what can be printed. The line between the people’s right to know and national security is not always clear. In 1971, the Supreme Court heard the Pentagon Papers case, in which the U.S. government sued the New York Times and the Washington Post to stop the release of information from a classified study of the Vietnam War. The Supreme Court ruled that while the government can impose prior restraint on the media, meaning the government can prevent the publication of information, that right is very limited. The court gave the newspapers the right to publish much of the study, but revelation of troop movements and the names of undercover operatives are some of the few approved reasons for which the government can stop publication or reporting. During the second Persian Gulf War, FOX News reporter Geraldo Rivera convinced the military to embed him with a U.S. Army unit in Iraq to provide live coverage of its day-to-day activities. During one of the reports he filed while traveling with the 101st Airborne Division, Rivera had his camera operator record him drawing a map in the sand, showing where his unit was and using Baghdad as a reference point. Rivera then discussed where the unit would go next. Rivera was immediately removed from the unit and escorted from Iraq. 66 The military exercised its right to maintain secrecy over troop movements, stating that Rivera’s reporting had given away troop locations and compromised the safety of the unit. Rivera’s future transmissions and reporting were censored until he was away from the unit. MEDIA AND FCC REGULATIONS The liberties enjoyed by newspapers are overseen by the U.S. court system, while television and radio broadcasters are monitored by both the courts and a government regulatory commission. The Radio Act of 1927 was the first attempt by Congress to regulate broadcast materials. The act was written to organize the rapidly expanding number of radio stations and the overuse of frequencies. But politicians feared that broadcast material would be obscene or biased. The Radio Act thus contained language that gave the government control over the quality of programming sent over public airwaves, and the power to ensure that stations maintained the public’s best interest. 67 The Communications Act of 1934 replaced the Radio Act and created a more powerful entity to monitor the airwaves—a seven-member Federal Communications Commission (FCC) to oversee both radio and telephone communication. The FCC, which now has only five members ( Figure 8.13 ), requires radio stations to apply for licenses, granted only if stations follow rules about limiting advertising, providing a public forum for discussion, and serving local and minority communities. With the advent of television, the FCC was given the same authority to license and monitor television stations. The FCC now also enforces ownership limits to avoid monopolies and censors materials deemed inappropriate. It has no jurisdiction over print media, mainly because print media are purchased and not broadcast. Link to Learning Concerned about something you heard or viewed? Would you like to file a complaint about an obscene radio program or place your phone number on the Do Not Call list? The FCC oversees each of these. To maintain a license, stations are required to meet a number of criteria. The equal-time rule , for instance, states that registered candidates running for office must be given equal opportunities for airtime and advertisements at non-cable television and radio stations beginning forty-five days before a primary election and sixty days before a general election. Should WBNS in Columbus, Ohio, agree to sell Senator Marco Rubio thirty seconds of airtime for a presidential campaign commercial, the station must also sell all other candidates in that race thirty seconds of airtime at the same price. This rate cannot be more than the station charges favored commercial advertisers that run ads of the same class and during the same time period. 68 More importantly, should Fox5 in Atlanta give Bernie Sanders five minutes of free airtime for an infomercial, the station must honor requests from all other candidates in the race for five minutes of free equal air time or a complaint may be filed with the FCC. 69 In 2015, Donald Trump, when he was running for the Republican presidential nomination, appeared on Saturday Night Live . Other Republican candidates made equal time requests, and NBC agreed to give each candidate twelve minutes and five seconds of air time on a Friday and Saturday night, as well as during a later episode of Saturday Night Live . 70 The FCC does waive the equal-time rule if the coverage is purely news. If a newscaster is covering a political rally and is able to secure a short interview with a candidate, equal time does not apply. Likewise, if a news programs creates a short documentary on the problem of immigration reform and chooses to include clips from only one or two candidates, the rule does not apply. 71 But the rule may include shows that are not news. For this reason, some stations will not show a movie or television program if a candidate appears in it. In 2003, Arnold Schwarzenegger and Gary Coleman, both actors, became candidates in California’s gubernatorial recall election. Television stations did not run Coleman’s sitcom Diff’rent Strokes or Schwarzenegger’s movies, because they would have been subject to the equal time provision. With 135 candidates on the official ballot, stations would have been hard-pressed to offer thirty-minute and two-hour time slots to all. 72 Even the broadcasting of the president’s State of the Union speech can trigger the equal-time provisions. Opposing parties in Congress now use their time immediately following the State of the Union to offer an official rebuttal to the president’s proposals. 73 While the idea behind the equal-time rule is fairness, it may not apply beyond candidates to supporters of that candidate or of a cause. Hence, there potentially may be a loophole in which broadcasters can give free time to just one candidate’s supporters. In the 2012 Wisconsin gubernatorial recall election, Scott Walker’s supporters were allegedly given free air time to raise funds and ask for volunteers while opponent Tom Barrett’s supporters were not. 74 According to someone involved in the case, the FCC declined to intervene after a complaint was filed on the matter, saying the equal-time rule applied only to the actual candidates, and that the case was an instance of the now-dead fairness doctrine . 75 The fairness doctrine was instituted in 1949 and required licensed stations to cover controversial issues in a balanced manner by providing listeners with information about all perspectives on any controversial issue. If one candidate, cause, or supporter was given an opportunity to reach the viewers or listeners, the other side was to be given a chance to present its side as well. The fairness doctrine ended in the 1980s, after a succession of court cases led to its repeal by the FCC in 1987, with stations and critics arguing the doctrine limited debate of controversial topics and placed the government in the role of editor. 76 The FCC also maintains indecency regulations over television, radio, and other broadcasters, which limit indecent material and keep the public airwaves free of obscene material. 77 While the Supreme Court has declined to define obscenity, it is identified using a test outlined in Miller v. California (1973). 78 Under the Miller test, obscenity is something that appeals to deviants, breaks local or state laws, and lacks value. 79 The Supreme Court determined that the presence of children in the audience trumped the right of broadcasters to air obscene and profane programming. However, broadcasters can show indecent programming or air profane language between the hours of 10 p.m. and 6 a.m. 80 The Supreme Court has also affirmed that the FCC has the authority to regulate content. When a George Carlin skit was aired on the radio with a warning that material might be offensive, the FCC still censored it. The station appealed the decision and lost. 81 Fines can range from tens of thousands to millions of dollars, and many are levied for sexual jokes on radio talk shows and nudity on television. In 2004, Janet Jackson’s wardrobe malfunction during the Super Bowl’s half-time show cost the CBS network $550,000. While some FCC violations are witnessed directly by commission members, like Jackson’s exposure at the Super Bowl, the FCC mainly relies on citizens and consumers to file complaints about violations of equal time and indecency rules. Approximately 2 percent of complaints to the FCC are about radio programming and 10 percent about television programming, compared to 71 percent about telephone complaints and 15 percent about Internet complaints. 82 Yet what constitutes a violation is not always clear for citizens wishing to complain, nor is it clear what will lead to a fine or license revocation. In October 2014, parent advocacy groups and consumers filed complaints and called for the FCC to fine ABC for running a sexually charged opening scene in the drama Scandal immediately after It’s the Great Pumpkin, Charlie Brown —without an ad or the cartoon’s credits to act as a buffer between the very different types of programming. 83 The FCC did not fine ABC. The Telecommunications Act of 1996 brought significant changes to the radio and television industries. It dropped the limit on the number of radio stations (forty) and television stations (twelve) a single company could own. It also allowed networks to purchase large numbers of cable stations. In essence, it reduced competition and increased the number of conglomerates. Some critics, such as Common Cause, argue that the act also raised cable prices and made it easier for companies to neglect their public interest obligations. 84 The act also changed the role of the FCC from regulator to monitor. The Commission oversees the purchase of stations to avoid media monopolies and adjudicates consumer complaints against radio, television, and telephone companies. Finding a Middle Ground Watch Dog or Paparazzi? We expect the media to keep a close eye on the government. But at what point does the media coverage cross from informational to sensational? In 2012, former secretary of state Hillary Clinton was questioned about her department’s decisions regarding the U.S. consulate in Benghazi, Libya. The consulate had been bombed by militants, leading to the death of an ambassador and a senior service officer. It was clear the United States had some knowledge that there was a threat to the consulate, and officials wondered whether requests to increase security at the consulate had been ignored. Clinton was asked to appear before a House Select Committee to answer questions, and the media began its coverage. While some journalists limited their reporting to Benghazi, others did not. Clinton was hounded about everything from her illness (dubbed the “Benghazi-flu”) to her clothing to her facial expressions to her choice of eyeglasses. 85 Even her hospital stay was questioned. 86 Some argued the expanded coverage was due to political attacks on Clinton, who at that time was widely perceived to be the top contender for the Democratic presidential nomination in 2016. 87 Republican majority leader Kevin McCarthy later implied that the hearings were an attempt to make Clinton look untrustworthy. 88 Yet Clinton was again brought before the House Select Committee on Benghazi as late as October 2015 ( Figure 8.14 ). This coverage should lead us to question whether the media gives us the information we need, or the information we want. Were people concerned about an attack on U.S. state officials working abroad, or did they just want to read rumors and attacks on Clinton? Did Republicans use the media’s tendency to pursue a target as a way to hurt Clinton in the polls? If the media gives us what we want, the answer seems to be that we wanted the media to act as both watchdog and paparazzi. How should the press have acted in this case if it were behaving only as the watchdog of democracy? MEDIA AND TRANSPARENCY The press has had some assistance in performing its muckraking duty. Laws that mandate federal and many state government proceedings and meeting documents be made available to the public are called sunshine laws . Proponents believe that open disagreements allow democracy to flourish and darkness allows corruption to occur. Opponents argue that some documents and policies are sensitive, and that the sunshine laws can inhibit policymaking. While some documents may be classified due to national or state security, governments are encouraged to limit the over-classification of documents. The primary legal example for sunshine laws is the Freedom of Information Act (FOIA) , passed in 1966 and signed by President Lyndon B. Johnson. The act requires the executive branch of the U.S. government to provide information requested by citizens and was intended to increase openness in the executive branch, which had been criticized for hiding information. Citizens wishing to obtain information may request documents from the appropriate agencies, and agencies may charge fees if the collection and copying of the requested documentation requires time and labor. 89 FOIA also identifies data that does not need to be disclosed, such as human resource and medical records, national defense records, and material provided by confidential sources, to name a few. 90 Not all presidents have embraced this openness, however. President Ronald Reagan, in 1981, exempted the CIA and FBI from FOIA requests. 91 Information requests have increased significantly in recent years, with U.S. agencies receiving over 700,000 requests in 2014, many directed to the Departments of State and Defense, thus creating a backlog. 92 Link to Learning Want to request a government document but unsure where to start? If the agency is a part of the U.S. government, the Freedom of Information Act portal will help you out. Few people file requests for information because most assume the media will find and report on important problems. And many people, including the press, assume the government, including the White House, sufficiently answers questions and provides information about government actions and policies. This expectation is not new. During the Civil War, journalists expected to have access to those representing the government, including the military. But William Tecumseh Sherman , a Union general, maintained distance between the press and his military. Following the publication of material Sherman believed to be protected by government censorship, a journalist was arrested and nearly put to death. The event spurred the creation of accreditation for journalists, which meant a journalist must be approved to cover the White House and the military before entering a controlled area. All accredited journalists also need approval by military field commanders before coming near a military zone. 93 To cover war up close, more journalists are asking to travel with troops during armed conflict. In 2003, George W. Bush ’s administration decided to allow more journalists in the field, hoping the concession would reduce friction between the military and the press. The U.S. Department of Defense placed fifty-eight journalists in a media boot camp to prepare them to be embedded with military regiments in Iraq. Although the increase in embedded journalists resulted in substantial in-depth coverage, many journalists felt their colleagues performed poorly, acting as celebrities rather than reporters. 94 The line between journalists’ expectation of openness and the government’s willingness to be open has continued to be a point of contention. Some administrations use the media to increase public support during times of war, as Woodrow Wilson did in World War I. Other presidents limit the media in order to limit dissent. In 1990, during the first Persian Gulf War, journalists received all publication material from the military in a prepackaged and staged manner. Access to Dover, the air force base that receives coffins of U.S. soldiers who die overseas, was closed. Journalists accused George H. W. Bush’s administration of limiting access and forcing them to produce bad pieces. The White House believed it controlled the message. 95 The ban was later lifted. In his 2008 presidential run, Barack Obama promised to run a transparent White House. 96 Yet once in office, he found that transparency makes it difficult to get work done, and so he limited access and questions. In his first year in office, George W. Bush, who was criticized by Obama as having a closed government, gave 147 question-and-answer sessions with journalists, while Obama gave only 46. Even Helen Thomas, a long-time liberal White House press correspondent, said the Obama administration tried to control both information and journalists ( Figure 8.15 ). 97 Because White House limitations on the press are not unusual, many journalists rely on confidential sources. In 1972, under the cloak of anonymity, the associate director of the Federal Bureau of Investigation, Mark Felt , became a news source for Bob Woodward and Carl Bernstein , political reporters at the Washington Post . Felt provided information about a number of potential stories and was Woodward’s main source for information about President Richard Nixon’s involvement in a series of illegal activities, including the break-in at Democratic Party headquarters in Washington’s Watergate office complex. The information eventually led to Nixon’s resignation and the indictment of sixty-nine people in his administration. Felt was nicknamed “ Deep Throat ,” and the journalists kept his identity secret until 2005. 98 The practice of granting anonymity to sources is sometimes referred to as reporter’s privilege . Fueled by the First Amendment’s protection of the press, journalists have long offered to keep sources confidential to protect them from government prosecution. To illustrate, as part of the investigation into the outing of Valerie Plame as a CIA officer, New York Times reporter Judith Miller was jailed for refusing to reveal “Scooter” Libby, Vice President Dick Cheney’s chief of staff, as her confidential government source. 99 Reporter’s privilege has increased the number of instances in which whistleblowers and government employees have given journalists tips or documents to prompt investigation into questionable government practices. Edward Snowden’s 2013 leak to the press regarding the U.S. government’s massive internal surveillance and tapping program was one such case. In 1972, however, the Supreme Court determined that journalists are not exempt from subpoenas and that courts could force testimony to name a confidential source. Journalists who conceal a source and thereby protect him or her from being properly tried for a crime may spend time in jail for contempt of court. In the case of Branzburg v. Hayes (1972), three journalists were placed in contempt of court for refusing to divulge sources. 100 The journalists appealed to the Supreme Court. In a 5–4 decision, the justices determined that freedom of the press did not extend to the confidentiality of sources. A concurring opinion did state that the case should be seen as a limited ruling, however. If the government needed to know a source due to a criminal trial, it could pursue the name of that source. 101 More recently, the Supreme Court refused to hear an appeal from New York Times journalist James Risen, who was subpoenaed and ordered to name a confidential source who had provided details about a U.S. government mission designed to harm Iran’s nuclear arms program. Risen was finally released from the subpoena, but the battle took seven years and the government eventually collected enough other evidence to make his testimony less crucial to the case. 102 Overall, the transparency of the government is affected more by the executive currently holding office than by the First Amendment. 8.4 The Impact of the Media Learning Objectives By the end of this section, you will be able to: Identify forms of bias that exist in news coverage and ways the media can present biased coverage Explain how the media cover politics and issues Evaluate the impact of the media on politics and policymaking In what ways can the media affect society and government? The media’s primary duty is to present us with information and alert us when important events occur. This information may affect what we think and the actions we take. The media can also place pressure on government to act by signaling a need for intervention or showing that citizens want change. For these reasons, the quality of the media’s coverage matters. MEDIA EFFECTS AND BIAS Concerns about the effects of media on consumers and the existence and extent of media bias go back to the 1920s. Reporter and commentator Walter Lippmann noted that citizens have limited personal experience with government and the world and posited that the media, through their stories, place ideas in citizens’ minds. These ideas become part of the citizens’ frame of reference and affect their decisions. Lippmann’s statements led to the hypodermic theory , which argues that information is “shot” into the receiver’s mind and readily accepted. 103 Yet studies in the 1930s and 1940s found that information was transmitted in two steps, with one person reading the news and then sharing the information with friends. People listened to their friends, but not to those with whom they disagreed. The newspaper’s effect was thus diminished through conversation. This discovery led to the minimal effects theory , which argues the media have little effect on citizens and voters. 104 By the 1970s, a new idea, the cultivation theory , hypothesized that media develop a person’s view of the world by presenting a perceived reality. 105 What we see on a regular basis is our reality. Media can then set norms for readers and viewers by choosing what is covered or discussed. In the end, the consensus among observers is that media have some effect, even if the effect is subtle. This raises the question of how the media, even general newscasts, can affect citizens. One of the ways is through framing : the creation of a narrative, or context, for a news story. The news often uses frames to place a story in a context so the reader understands its importance or relevance. Yet, at the same time, framing affects the way the reader or viewer processes the story. Episodic framing occurs when a story focuses on isolated details or specifics rather than looking broadly at a whole issue. Thematic framing takes a broad look at an issue and skips numbers or details. It looks at how the issue has changed over a long period of time and what has led to it. For example, a large, urban city is dealing with the problem of an increasing homeless population, and the city has suggested ways to improve the situation. If journalists focus on the immediate statistics, report the current percentage of homeless people, interview a few, and look at the city’s current investment in a homeless shelter, the coverage is episodic. If they look at homelessness as a problem increasing everywhere, examine the reasons people become homeless, and discuss the trends in cities’ attempts to solve the problem, the coverage is thematic. Episodic frames may create more sympathy, while a thematic frame may leave the reader or viewer emotionally disconnected and less sympathetic ( Figure 8.16 ). Link to Learning For a closer look at framing and how it influences voters, read “How the Media Frames Political Issues” , a review essay by Scott London. Framing can also affect the way we see race, socioeconomics, or other generalizations. For this reason, it is linked to priming : when media coverage predisposes the viewer or reader to a particular perspective on a subject or issue. If a newspaper article focuses on unemployment, struggling industries, and jobs moving overseas, the reader will have a negative opinion about the economy. If then asked whether he or she approves of the president’s job performance, the reader is primed to say no. Readers and viewers are able to fight priming effects if they are aware of them or have prior information about the subject. COVERAGE EFFECTS ON GOVERNANCE AND CAMPAIGNS When it is spotty, the media’s coverage of campaigns and government can sometimes affect the way government operates and the success of candidates. In 1972, for instance, the McGovern-Fraser reforms created a voter-controlled primary system, so party leaders no longer pick the presidential candidates. Now the media are seen as kingmakers and play a strong role in influencing who will become the Democratic and Republican nominees in presidential elections. They can discuss the candidates’ messages, vet their credentials, carry sound bites of their speeches, and conduct interviews. The candidates with the most media coverage build momentum and do well in the first few primaries and caucuses. This, in turn, leads to more media coverage, more momentum, and eventually a winning candidate. Thus, candidates need the media. In the 1980s, campaigns learned that tight control on candidate information created more favorable media coverage. In the presidential election of 1984, candidates Ronald Reagan and George H. W. Bush began using an issue-of-the-day strategy, providing quotes and material on only one topic each day. This strategy limited what journalists could cover because they had only limited quotes and sound bites to use in their reports. In 1992, both Bush’s and Bill Clinton’s campaigns maintained their carefully drawn candidate images by also limiting photographers and television journalists to photo opportunities at rallies and campaign venues. The constant control of the media became known as the “bubble,” and journalists were less effective when they were in the campaign’s bubble. Reporters complained this coverage was campaign advertising rather than journalism, and a new model emerged with the 1996 election. 106 Campaign coverage now focuses on the spectacle of the season, rather than providing information about the candidates. Colorful personalities, strange comments, lapse of memories, and embarrassing revelations are more likely to get air time than the candidates’ issue positions. Donald Trump may be the best example of shallower press coverage of a presidential election. Some argue that newspapers and news programs are limiting the space they allot to discussion of the campaigns. 107 Others argue that citizens want to see updates on the race and electoral drama, not boring issue positions or substantive reporting. 108 It may also be that journalists have tired of the information games played by politicians and have taken back control of the news cycles. 109 All these factors have likely led to the shallow press coverage we see today, sometimes dubbed pack journalism because journalists follow one another rather than digging for their own stories. Television news discusses the strategies and blunders of the election, with colorful examples. Newspapers focus on polls. In an analysis of the 2012 election, Pew Research found that 64 percent of stories and coverage focused on campaign strategy. Only 9 percent covered domestic issue positions; 6 percent covered the candidates’ public records; and, 1 percent covered their foreign policy positions. 110 For better or worse, coverage of the candidates’ statements get less air time on radio and television, and sound bites, or clips, of their speeches have become even shorter. In 1968, the average sound bite from Richard Nixon was 42.3 seconds, while a recent study of television coverage found that sound bites had decreased to only eight seconds in the 2004 election. 111 The clips chosen to air were attacks on opponents 40 percent of the time. Only 30 percent contained information about the candidate’s issues or events. The study also found the news showed images of the candidates, but for an average of only twenty-five seconds while the newscaster discussed the stories. 112 This study supports the argument that shrinking sound bites are a way for journalists to control the story and add their own analysis rather than just report on it. 113 Candidates are given a few minutes to try to argue their side of an issue, but some say television focuses on the argument rather than on information. In 2004, Jon Stewart of Comedy Central’s The Daily Show began attacking the CNN program Crossfire for being theater, saying the hosts engaged in reactionary and partisan arguing rather than true debating. 114 Some of Stewart’s criticisms resonated, even with host Paul Begala, and Crossfire was later pulled from the air. 115 The media’s discussion of campaigns has also grown negative. Although biased campaign coverage dates back to the period of the partisan press, the increase in the number of cable news stations has made the problem more visible. Stations like FOX News and MSNBC are overt in their use of bias in framing stories. During the 2012 campaign, seventy-one of seventy-four MSNBC stories about Mitt Romney were highly negative, while FOX News’ coverage of Obama had forty-six out of fifty-two stories with negative information ( Figure 8.17 ). The major networks—ABC, CBS, and NBC—were somewhat more balanced, yet the overall coverage of both candidates tended to be negative. 116 Due in part to the lack of substantive media coverage, campaigns increasingly use social media to relay their message. Candidates can create their own sites and pages and try to spread news through supporters to the undecided. In 2012, both Romney and Obama maintained Facebook, Twitter, and YouTube accounts to provide information to voters. Yet, on social media, candidates still need to combat negativity, from both the opposition and supporters. Stories about Romney that appeared in the mainstream media were negative 38 percent of the time, while his coverage in Facebook news was negative 62 percent of the time and 58 percent of the time on Twitter. 117 In the 2016 election cycle, both party nominees heavily used social media. Donald Trump’s scores of tweets became very prominent as he tweeted during Clinton’s convention acceptance speech and sometimes at all hours of the night. Clinton also used Twitter, but less so than Trump, though arguably staying better on message. Trump tended to rail on about topics and at one point was even drawn into a Twitter battle with Senator Elizabeth Warren (D-MA). Hillary Clinton also used Facebook for longer messages and imaging. Once candidates are in office, the chore of governing begins, with the added weight of media attention. Historically, if presidents were unhappy with their press coverage, they used personal and professional means to change its tone. Franklin D. Roosevelt, for example, was able to keep journalists from printing stories through gentleman’s agreements, loyalty, and the provision of additional information, sometimes off the record. The journalists then wrote positive stories, hoping to keep the president as a source. John F. Kennedy hosted press conferences twice a month and opened the floor for questions from journalists, in an effort to keep press coverage positive. 118 When presidents and other members of the White House are not forthcoming with information, journalists must press for answers. Dan Rather, a journalist for CBS, regularly sparred with presidents in an effort to get information. When Rather interviewed Richard Nixon about Vietnam and Watergate, Nixon was hostile and uncomfortable. 119 In a 1988 interview with then-vice president George H. W. Bush, Bush accused Rather of being argumentative about the possible cover-up of a secret arms sale with Iran: Rather: I don’t want to be argumentative, Mr. Vice President. Bush: You do, Dan. Rather: No—no, sir, I don’t. Bush: This is not a great night, because I want to talk about why I want to be president, why those 41 percent of the people are supporting me. And I don’t think it’s fair to judge my whole career by a rehash of Iran. How would you like it if I judged your career by those seven minutes when you walked off the set in New York? 120 Cabinet secretaries and other appointees also talk with the press, sometimes making for conflicting messages. The creation of the position of press secretary and the White House Office of Communications both stemmed from the need to send a cohesive message from the executive branch. Currently, the White House controls the information coming from the executive branch through the Office of Communications and decides who will meet with the press and what information will be given. But stories about the president often examine personality, or the president’s ability to lead the country, deal with Congress, or respond to national and international events. They are less likely to cover the president’s policies or agendas without a lot of effort on the president’s behalf. 121 When Obama first entered office in 2009, journalists focused on his battles with Congress, critiquing his leadership style and inability to work with Representative Nancy Pelosi, then Speaker of the House. To gain attention for his policies, specifically the American Recovery and Reinvestment Act (ARRA), Obama began traveling the United States to draw the media away from Congress and encourage discussion of his economic stimulus package. Once the ARRA had been passed, Obama began travelling again, speaking locally about why the country needed the Affordable Care Act and guiding media coverage to promote support for the act. 122 Congressional representatives have a harder time attracting media attention for their policies. House and Senate members who use the media well, either to help their party or to show expertise in an area, may increase their power within Congress, which helps them bargain for fellow legislators’ votes. Senators and high-ranking House members may also be invited to appear on cable news programs as guests, where they may gain some media support for their policies. Yet, overall, because there are so many members of Congress, and therefore so many agendas, it is harder for individual representatives to draw media coverage. 123 It is less clear, however, whether media coverage of an issue leads Congress to make policy, or whether congressional policymaking leads the media to cover policy. In the 1970s, Congress investigated ways to stem the number of drug-induced deaths and crimes. As congressional meetings dramatically increased, the press was slow to cover the topic. The number of hearings was at its highest from 1970 to 1982, yet media coverage did not rise to the same level until 1984. 124 Subsequent hearings and coverage led to national policies like DARE and First Lady Nancy Reagan’s “Just Say No” campaign ( Figure 8.18 ). Later studies of the media’s effect on both the president and Congress report that the media has a stronger agenda-setting effect on the president than on Congress. What the media choose to cover affects what the president thinks is important to voters, and these issues were often of national importance. The media’s effect on Congress was limited, however, and mostly extended to local issues like education or child and elder abuse. 125 If the media are discussing a topic, chances are a member of Congress has already submitted a relevant bill, and it is waiting in committee. COVERAGE EFFECTS ON SOCIETY The media choose what they want to discuss. This agenda setting creates a reality for voters and politicians that affects the way people think, act, and vote. Even if the crime rate is going down, for instance, citizens accustomed to reading stories about assault and other offenses still perceive crime to be an issue. 126 Studies have also found that the media’s portrayal of race is flawed, especially in coverage of crime and poverty. One study revealed that local news shows were more likely to show pictures of criminals when they were African American, so they overrepresented blacks as perpetrators and whites as victims. 127 A second study found a similar pattern in which Latinos were underrepresented as victims of crime and as police officers, while whites were overrepresented as both. 128 Voters were thus more likely to assume that most criminals are black and most victims and police officers are white, even though the numbers do not support those assumptions. Network news similarly misrepresents the victims of poverty by using more images of blacks than whites in its segments. Viewers in a study were left believing African Americans were the majority of the unemployed and poor, rather than seeing the problem as one faced by many races. 129 The misrepresentation of race is not limited to news coverage, however. A study of images printed in national magazines, like Time and Newsweek , found they also misrepresented race and poverty. The magazines were more likely to show images of young African Americans when discussing poverty and excluded the elderly and the young, as well as whites and Latinos, which is the true picture of poverty. 130 Racial framing, even if unintentional, affects perceptions and policies. If viewers are continually presented with images of African Americans as criminals, there is an increased chance they will perceive members of this group as violent or aggressive. 131 The perception that most recipients of welfare are working-age African Americans may have led some citizens to vote for candidates who promised to reduce welfare benefits. 132 When survey respondents were shown a story of a white unemployed individual, 71 percent listed unemployment as one of the top three problems facing the United States, while only 53 percent did so if the story was about an unemployed African American. 133 Word choice may also have a priming effect. News organizations like the Los Angeles Times and the Associated Press no longer use the phrase “illegal immigrant” to describe undocumented residents. This may be due to the desire to create a “sympathetic” frame for the immigration situation rather than a “threat” frame. 134 Media coverage of women has been similarly biased. Most journalists in the early 1900s were male, and women’s issues were not part of the newsroom discussion. As journalist Kay Mills put it, the women’s movement of the 1960s and 1970s was about raising awareness of the problems of equality, but writing about rallies “was like trying to nail Jell-O to the wall.” 135 Most politicians, business leaders, and other authority figures were male, and editors’ reactions to the stories were lukewarm. The lack of women in the newsroom, politics, and corporate leadership encouraged silence. 136 In 1976, journalist Barbara Walters became the first female coanchor on a network news show, The ABC Evening News . She was met with great hostility from her coanchor Harry Reasoner and received critical coverage from the press. 137 On newspaper staffs, women reported having to fight for assignments to well-published beat s , or to be assigned areas or topics, such as the economy or politics, that were normally reserved for male journalists. Once female journalists held these assignments, they feared writing about women’s issues. Would it make them appear weak? Would they be taken from their coveted beats? 138 This apprehension allowed poor coverage of women and the women’s movement to continue until women were better represented as journalists and as editors. Strength of numbers allowed them to be confident when covering issues like health care, childcare, and education. 139 Link to Learning The Center for American Women in Politics researches the treatment women receive from both government and the media, and they share the data with the public. The media’s historically uneven coverage of women continues in its treatment of female candidates. Early coverage was sparse. The stories that did appear often discussed the candidate’s viability, or ability to win, rather than her stand on the issues. 140 Women were seen as a novelty rather than as serious contenders who needed to be vetted and discussed. Modern media coverage has changed slightly. One study found that female candidates receive more favorable coverage than in prior generations, especially if they are incumbents. 141 Yet a different study found that while there was increased coverage for female candidates, it was often negative. 142 And it did not include Latina candidates. 143 Without coverage, they are less likely to win. The historically negative media coverage of female candidates has had another concrete effect: Women are less likely than men to run for office. One common reason is the effect negative media coverage has on families. 144 Many women do not wish to expose their children or spouses to criticism. 145 In 2008, the nomination of Sarah Palin as Republican candidate John McCain’s running mate validated this concern ( Figure 8.19 ). Some articles focused on her qualifications to be a potential future president or her record on the issues. But others questioned whether she had the right to run for office, given she had young children, one of whom has developmental disabilities. 146 Her daughter, Bristol, was criticized for becoming pregnant while unmarried. 147 Her husband was called cheap for failing to buy her a high-priced wedding ring. 148 Even when candidates ask that children and families be off-limits, the press rarely honors the requests. So women with young children may wait until their children are grown before running for office, if they choose to run at all.
microbiology
Summary 15.1 Characteristics of Infectious Disease In an infection , a microorganism enters a host and begins to multiply. Some infections cause disease , which is any deviation from the normal function or structure of the host. Signs of a disease are objective and are measured. Symptoms of a disease are subjective and are reported by the patient. Diseases can either be noninfectious (due to genetics and environment) or infectious (due to pathogens). Some infectious diseases are communicable (transmissible between individuals) or contagious (easily transmissible between individuals); others are noncommunicable , but may be contracted via contact with environmental reservoirs or animals ( zoonoses ) Nosocomial diseases are contracted in hospital settings, whereas iatrogenic disease are the direct result of a medical procedure An acute disease is short in duration, whereas a chronic disease lasts for months or years. Latent diseases last for years, but are distinguished from chronic diseases by the lack of active replication during extended dormant periods. The periods of disease include the incubation period , the prodromal period , the period of illness , the period of decline , and the period of convalescence . These periods are marked by changes in the number of infectious agents and the severity of signs and symptoms. 15.2 How Pathogens Cause Disease Koch’s postulates are used to determine whether a particular microorganism is a pathogen. Molecular Koch’s postulates are used to determine what genes contribute to a pathogen’s ability to cause disease. Virulence , the degree to which a pathogen can cause disease, can be quantified by calculating either the ID 50 or LD 50 of a pathogen on a given population. Primary pathogens are capable of causing pathological changes associated with disease in a healthy individual, whereas opportunistic pathogens can only cause disease when the individual is compromised by a break in protective barriers or immunosuppression. Infections and disease can be caused by pathogens in the environment or microbes in an individual’s resident microbiota . Infections can be classified as local , focal , or systemic depending on the extent to which the pathogen spreads in the body. A secondary infection can sometimes occur after the host’s defenses or normal microbiota are compromised by a primary infection or antibiotic treatment. Pathogens enter the body through portals of entry and leave through portals of exit . The stages of pathogenesis include exposure , adhesion , invasion , infection , and transmission . 15.3 Virulence Factors of Bacterial and Viral Pathogens Virulence factors contribute to a pathogen’s ability to cause disease. Exoenzymes and toxins allow pathogens to invade host tissue and cause tissue damage. Exoenzymes are classified according to the macromolecule they target and exotoxins are classified based on their mechanism of action. Bacterial toxins include endotoxin and exotoxins . Endotoxin is the lipid A component of the LPS of the gram-negative cell envelope. Exotoxins are proteins secreted mainly by gram-positive bacteria, but also are secreted by gram-negative bacteria. Bacterial pathogens may evade the host immune response by producing capsules to avoid phagocytosis, surviving the intracellular environment of phagocytes, degrading antibodies, or through antigenic variation . Viral pathogens use adhesins for initiating infections and antigenic variation to avoid immune defenses. Influenza viruses use both antigenic drift and antigenic shift to avoid being recognized by the immune system. 15.4 Virulence Factors of Eukaryotic Pathogens Fungal and parasitic pathogens use pathogenic mechanisms and virulence factors that are similar to those of bacterial pathogens Fungi initiate infections through the interaction of adhesins with receptors on host cells. Some fungi produce toxins and exoenzymes involved in disease production and capsules that provide protection of phagocytosis. Protozoa adhere to target cells through complex mechanisms and can cause cellular damage through release of cytopathic substances. Some protozoa avoid the immune system through antigenic variation and production of capsules. Helminthic worms are able to avoid the immune system by coating their exteriors with glycan molecules that make them look like host cells or by suppressing the immune system.
Chapter Outline 15.1 Characteristics of Infectious Disease 15.2 How Pathogens Cause Disease 15.3 Virulence Factors of Bacterial and Viral Pathogens 15.4 Virulence Factors of Eukaryotic Pathogens Introduction Jane woke up one spring morning feeling not quite herself. Her throat felt a bit dry and she was sniffling. She wondered why she felt so lousy. Was it because of a change in the weather? The pollen count? Was she coming down with something? Did she catch a bug from her coworker who sneezed on her in the elevator yesterday? The signs and symptoms we associate with illness can have many different causes. Sometimes they are the direct result of a pathogenic infection, but in other cases they result from a response by our immune system to a pathogen or another perceived threat. For example, in response to certain pathogens, the immune system may release pyrogens, chemicals that cause the body temperature to rise, resulting in a fever. This response creates a less-than-favorable environment for the pathogen, but it also makes us feel sick. Medical professionals rely heavily on analysis of signs and symptoms to determine the cause of an ailment and prescribe treatment. In some cases, signs and symptoms alone are enough to correctly identify the causative agent of a disease, but since few diseases produce truly unique symptoms, it is often necessary to confirm the identity of the infectious agent by other direct and indirect diagnostic methods.
[ { "answer": { "ans_choice": 2, "ans_text": "C" }, "bloom": null, "hl_context": "<hl> Unlike signs , symptom s of disease are subjective . <hl> <hl> Symptoms are felt or experienced by the patient , but they cannot be clinically confirmed or objectively measured . <hl> <hl> Examples of symptoms include nausea , loss of appetite , and pain . <hl> Such symptoms are important to consider when diagnosing disease , but they are subject to memory bias and are difficult to measure precisely . Some clinicians attempt to quantify symptoms by asking patients to assign a numerical value to their symptoms . For example , the Wong-Baker Faces pain-rating scale asks patients to rate their pain on a scale of 0 – 10 . An alternative method of quantifying pain is measuring skin conductance fluctuations . These fluctuations reflect sweating due to skin sympathetic nerve activity resulting from the stressor of pain . 1 1 F . Savino et al . “ Pain Assessment in Children Undergoing Venipuncture : The Wong – Baker Faces Scale Versus Skin Conductance Fluctuations . ” PeerJ 1 ( 2013 ): e37 ; https://peerj.com/articles/37/ <hl> The sign s of disease are objective and measurable , and can be directly observed by a clinician . <hl> Vital signs , which are used to measure the body ’ s basic functions , include body temperature ( normally 37 ° C [ 98.6 ° F ] ) , heart rate ( normally 60 – 100 beats per minute ) , breathing rate ( normally 12 – 18 breaths per minute ) , and blood pressure ( normally between 90/60 and 120/80 mm Hg ) . Changes in any of the body ’ s vital signs may be indicative of disease . <hl> For example , having a fever ( a body temperature significantly higher than 37 ° C or 98.6 ° F ) is a sign of disease because it can be measured . <hl> An infection is the successful colonization of a host by a microorganism . <hl> Infections can lead to disease , which causes signs and symptoms resulting in a deviation from the normal structure or functioning of the host . <hl> Microorganisms that can cause disease are known as pathogens .", "hl_sentences": "Unlike signs , symptom s of disease are subjective . Symptoms are felt or experienced by the patient , but they cannot be clinically confirmed or objectively measured . Examples of symptoms include nausea , loss of appetite , and pain . The sign s of disease are objective and measurable , and can be directly observed by a clinician . For example , having a fever ( a body temperature significantly higher than 37 ° C or 98.6 ° F ) is a sign of disease because it can be measured . Infections can lead to disease , which causes signs and symptoms resulting in a deviation from the normal structure or functioning of the host .", "question": { "cloze_format": "___ would be a sign of an infection.", "normal_format": "Which of the following would be a sign of an infection?", "question_choices": [ "muscle aches", "headache", "fever", "nausea" ], "question_id": "fs-id1167584979825", "question_text": "Which of the following would be a sign of an infection?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 1, "ans_text": "B" }, "bloom": null, "hl_context": "<hl> In contrast to communicable infectious diseases , a noncommunicable infectious disease is not spread from one person to another . <hl> One example is tetanus , caused by Clostridium tetani , a bacterium that produces endospores that can survive in the soil for many years . This disease is typically only transmitted through contact with a skin wound ; it cannot be passed from an infected person to another person . Similarly , Legionnaires disease is caused by Legionella pneumophila , a bacterium that lives within amoebae in moist locations like water-cooling towers . An individual may contract Legionnaires disease via contact with the contaminated water , but once infected , the individual cannot pass the pathogen to other individuals .", "hl_sentences": "In contrast to communicable infectious diseases , a noncommunicable infectious disease is not spread from one person to another .", "question": { "cloze_format": "___ is an example of a noncommunicable infectious disease.", "normal_format": "Which of the following is an example of a noncommunicable infectious disease?", "question_choices": [ "infection with a respiratory virus", "food poisoning due to a preformed bacterial toxin in food", "skin infection acquired from a dog bite", "infection acquired from the stick of a contaminated needle" ], "question_id": "fs-id1167584863097", "question_text": "Which of the following is an example of a noncommunicable infectious disease?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 3, "ans_text": "D" }, "bloom": null, "hl_context": "<hl> The prodromal period occurs after the incubation period . <hl> <hl> During this phase , the pathogen continues to multiply and the host begins to experience general signs and symptoms of illness , which typically result from activation of the immune system , such as fever , pain , soreness , swelling , or inflammation . <hl> Usually , such signs and symptoms are too general to indicate a particular disease . Following the prodromal period is the period of illness , during which the signs and symptoms of disease are most obvious and severe .", "hl_sentences": "The prodromal period occurs after the incubation period . During this phase , the pathogen continues to multiply and the host begins to experience general signs and symptoms of illness , which typically result from activation of the immune system , such as fever , pain , soreness , swelling , or inflammation .", "question": { "cloze_format": "The ___ period is the stage of disease during which the patient begins to present general signs and symptoms.", "normal_format": "Which period is the stage of disease during which the patient begins to present general signs and symptoms?", "question_choices": [ "convalescence", "incubation", "illness", "prodromal" ], "question_id": "fs-id1167583617658", "question_text": "Which period is the stage of disease during which the patient begins to present general signs and symptoms?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 0, "ans_text": "A" }, "bloom": null, "hl_context": "An infectious disease is any disease caused by the direct effect of a pathogen . A pathogen may be cellular ( bacteria , parasites , and fungi ) or acellular ( viruses , viroids , and prions ) . Some infectious diseases are also communicable , meaning they are capable of being spread from person to person through either direct or indirect mechanisms . <hl> Some infectious communicable diseases are also considered contagious diseases , meaning they are easily spread from person to person . <hl> <hl> Not all contagious diseases are equally so ; the degree to which a disease is contagious usually depends on how the pathogen is transmitted . <hl> For example , measles is a highly contagious viral disease that can be transmitted when an infected person coughs or sneezes and an uninfected person breathes in droplets containing the virus . Gonorrhea is not as contagious as measles because transmission of the pathogen ( Neisseria gonorrhoeae ) requires close intimate contact ( usually sexual ) between an infected person and an uninfected person .", "hl_sentences": "Some infectious communicable diseases are also considered contagious diseases , meaning they are easily spread from person to person . Not all contagious diseases are equally so ; the degree to which a disease is contagious usually depends on how the pathogen is transmitted .", "question": { "cloze_format": "A communicable disease that can be easily transmitted from person to person is a ___ disease.", "normal_format": "A communicable disease that can be easily transmitted from person to person is which type of disease?", "question_choices": [ "contagious", "iatrogenic", "acute", "nosocomial" ], "question_id": "fs-id1167583584429", "question_text": "A communicable disease that can be easily transmitted from person to person is which type of disease?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 2, "ans_text": "C" }, "bloom": null, "hl_context": "In 1988 , Stanley Falkow ( 1934 – ) proposed a revised form of Koch ’ s postulates known as molecular Koch ’ s postulates . These are listed in the left column of Table 15.4 . <hl> The premise for molecular Koch ’ s postulates is not in the ability to isolate a particular pathogen but rather to identify a gene that may cause the organism to be pathogenic . <hl> <hl> Koch also assumed that all pathogens are microorganisms that can be grown in pure culture ( postulate 2 ) and that animals could serve as reliable models for human disease . <hl> However , we now know that not all pathogens can be grown in pure culture , and many human diseases cannot be reliably replicated in animal hosts . Viruses and certain bacteria , including Rickettsia and Chlamydia , are obligate intracellular pathogens that can grow only when inside a host cell . If a microbe cannot be cultured , a researcher cannot move past postulate 2 . <hl> Likewise , without a suitable nonhuman host , a researcher cannot evaluate postulate 2 without deliberately infecting humans , which presents obvious ethical concerns . <hl> <hl> AIDS is an example of such a disease because the human immunodeficiency virus ( HIV ) only causes disease in humans . <hl> In 1884 , Koch published four postulates ( Table 15.3 ) that summarized his method for determining whether a particular microorganism was the cause of a particular disease . <hl> Each of Koch ’ s postulates represents a criterion that must be met before a disease can be positively linked with a pathogen . <hl> <hl> In order to determine whether the criteria are met , tests are performed on laboratory animals and cultures from healthy and diseased animals are compared ( Figure 15.4 ) . <hl>", "hl_sentences": "The premise for molecular Koch ’ s postulates is not in the ability to isolate a particular pathogen but rather to identify a gene that may cause the organism to be pathogenic . Koch also assumed that all pathogens are microorganisms that can be grown in pure culture ( postulate 2 ) and that animals could serve as reliable models for human disease . Likewise , without a suitable nonhuman host , a researcher cannot evaluate postulate 2 without deliberately infecting humans , which presents obvious ethical concerns . AIDS is an example of such a disease because the human immunodeficiency virus ( HIV ) only causes disease in humans . Each of Koch ’ s postulates represents a criterion that must be met before a disease can be positively linked with a pathogen . In order to determine whether the criteria are met , tests are performed on laboratory animals and cultures from healthy and diseased animals are compared ( Figure 15.4 ) .", "question": { "cloze_format": "___ is a pathogen that could not be identified by the original Koch’s postulates.", "normal_format": "Which of the following is a pathogen that could not be identified by the original Koch’s postulates?", "question_choices": [ "Staphylococcus aureus", "Pseudomonas aeruginosa", "Human immunodeficiency virus", "Salmonella enterica serovar Typhimurium" ], "question_id": "fs-id1167580152328", "question_text": "Which of the following is a pathogen that could not be identified by the original Koch’s postulates?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 0, "ans_text": "A" }, "bloom": null, "hl_context": "<hl> Virulence of a pathogen can be quantified using controlled experiments with laboratory animals . <hl> <hl> Two important indicators of virulence are the median infectious dose ( ID 50 ) and the median lethal dose ( LD 50 ) , both of which are typically determined experimentally using animal models . <hl> <hl> The ID 50 is the number of pathogen cells or virions required to cause active infection in 50 % of inoculated animals . <hl> The LD 50 is the number of pathogenic cells , virions , or amount of toxin required to kill 50 % of infected animals . To calculate these values , each group of animals is inoculated with one of a range of known numbers of pathogen cells or virions . In graphs like the one shown in Figure 15.5 , the percentage of animals that have been infected ( for ID 50 ) or killed ( for LD 50 ) is plotted against the concentration of pathogen inoculated . Figure 15.5 represents data graphed from a hypothetical experiment measuring the LD 50 of a pathogen . Interpretation of the data from this graph indicates that the LD 50 of the pathogen for the test animals is 10 4 pathogen cells or virions ( depending upon the pathogen studied ) .", "hl_sentences": "Virulence of a pathogen can be quantified using controlled experiments with laboratory animals . Two important indicators of virulence are the median infectious dose ( ID 50 ) and the median lethal dose ( LD 50 ) , both of which are typically determined experimentally using animal models . The ID 50 is the number of pathogen cells or virions required to cause active infection in 50 % of inoculated animals .", "question": { "cloze_format": "Pathogen A has an ID50 of 50 particles, pathogen B has an ID50 of 1,000 particles, and pathogen C has an ID50 of 1 × 106 particles. The pathogen that is most virulent is ___ .", "normal_format": "Pathogen A has an ID50 of 50 particles, pathogen B has an ID50 of 1,000 particles, and pathogen C has an ID50 of 1 × 106 particles. Which pathogen is most virulent?", "question_choices": [ "pathogen A", "pathogen B", "pathogen C" ], "question_id": "fs-id1167582423366", "question_text": "Pathogen A has an ID50 of 50 particles, pathogen B has an ID50 of 1,000 particles, and pathogen C has an ID50 of 1 × 106 particles. Which pathogen is most virulent?" }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 2, "ans_text": "C" }, "bloom": null, "hl_context": "<hl> To cause disease , a pathogen must successfully achieve four steps or stages of pathogenesis : exposure ( contact ) , adhesion ( colonization ) , invasion , and infection . <hl> The pathogen must be able to gain entry to the host , travel to the location where it can establish an infection , evade or overcome the host ’ s immune response , and cause damage ( i . e . , disease ) to the host . In many cases , the cycle is completed when the pathogen exits the host and is transmitted to a new host .", "hl_sentences": "To cause disease , a pathogen must successfully achieve four steps or stages of pathogenesis : exposure ( contact ) , adhesion ( colonization ) , invasion , and infection .", "question": { "cloze_format": "The choice that lists the steps of pathogenesis in the correct order is ___.", "normal_format": "Which of the following choices lists the steps of pathogenesis in the correct order?", "question_choices": [ "invasion, infection, adhesion, exposure", "adhesion, exposure, infection, invasion", "exposure, adhesion, invasion, infection", "disease, infection, exposure, invasion" ], "question_id": "fs-id1167582472838", "question_text": "Which of the following choices lists the steps of pathogenesis in the correct order?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 0, "ans_text": "A" }, "bloom": null, "hl_context": "Entry to a cell can occur by endocytosis . <hl> For most kinds of host cells , pathogens use one of two different mechanisms for endocytosis and entry . <hl> <hl> One mechanism relies on effector proteins secreted by the pathogen ; these effector proteins trigger entry into the host cell . <hl> This is the method that Salmonella and Shigella use when invading intestinal epithelial cells . When these pathogens come in contact with epithelial cells in the intestine , they secrete effector molecules that cause protrusions of membrane ruffles that bring the bacterial cell in . This process is called membrane ruffling . <hl> The second mechanism relies on surface proteins expressed on the pathogen that bind to receptors on the host cell , resulting in entry . <hl> For example , Yersinia pseudotuberculosis produces a surface protein known as invasin that binds to beta - 1 integrins expressed on the surface of host cells .", "hl_sentences": "For most kinds of host cells , pathogens use one of two different mechanisms for endocytosis and entry . One mechanism relies on effector proteins secreted by the pathogen ; these effector proteins trigger entry into the host cell . The second mechanism relies on surface proteins expressed on the pathogen that bind to receptors on the host cell , resulting in entry .", "question": { "cloze_format": "___ would be a virulence factor of a pathogen.", "normal_format": "Which of the following would be a virulence factor of a pathogen?", "question_choices": [ "a surface protein allowing the pathogen to bind to host cells", "a secondary host the pathogen can infect", "a surface protein the host immune system recognizes", "the ability to form a provirus" ], "question_id": "fs-id1167585080299", "question_text": "Which of the following would be a virulence factor of a pathogen?" }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 0, "ans_text": "A" }, "bloom": null, "hl_context": "Whereas coagulase causes blood to clot , kinases have the opposite effect by triggering the conversion of plasminogen to plasmin , which is involved in the digestion of fibrin clots . <hl> By digesting a clot , kinases allow pathogens trapped in the clot to escape and spread , similar to the way that collagenase , hyaluronidase , and DNAse facilitate the spread of infection . <hl> Examples of kinases include staphylokinases and streptokinases , produced by Staphylococcus aureus and Streptococcus pyogenes , respectively . It is intriguing that S . aureus can produce both coagulase to promote clotting and staphylokinase to stimulate the digestion of clots . The action of the coagulase provides an important protective barrier from the immune system , but when nutrient supplies are diminished or other conditions signal a need for the pathogen to escape and spread , the production of staphylokinase can initiate this process .", "hl_sentences": "By digesting a clot , kinases allow pathogens trapped in the clot to escape and spread , similar to the way that collagenase , hyaluronidase , and DNAse facilitate the spread of infection .", "question": { "cloze_format": "A statement that applies to hyaluronidase is that ___.", "normal_format": "Which of the following applies to hyaluronidase?", "question_choices": [ "It acts as a spreading factor.", "It promotes blood clotting.", "It is an example of an adhesin.", "It is produced by immune cells to target pathogens." ], "question_id": "fs-id1167583580324", "question_text": "Which of the following applies to hyaluronidase?" }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 3, "ans_text": "D" }, "bloom": null, "hl_context": "<hl> Enzymes that degrade the phospholipids of cell membranes are called phospholipases . <hl> Their actions are specific in regard to the type of phospholipids they act upon and where they enzymatically cleave the molecules . <hl> The pathogen responsible for anthrax , B . anthracis , produces phospholipase C . When B . anthracis is ingested by phagocytic cells of the immune system , phospholipase C degrades the membrane of the phagosome before it can fuse with the lysosome , allowing the pathogen to escape into the cytoplasm and multiply . <hl> Phospholipases can also target the membrane that encloses the phagosome within phagocytic cells . As described earlier in this chapter , this is the mechanism used by intracellular pathogens such as L . monocytogenes and Rickettsia to escape the phagosome and multiply within the cytoplasm of phagocytic cells . The role of phospholipases in bacterial virulence is not restricted to phagosomal escape . Many pathogens produce phospholipases that act to degrade cell membranes and cause lysis of target cells . These phospholipases are involved in lysis of red blood cells , white blood cells , and tissue cells .", "hl_sentences": "Enzymes that degrade the phospholipids of cell membranes are called phospholipases . The pathogen responsible for anthrax , B . anthracis , produces phospholipase C . When B . anthracis is ingested by phagocytic cells of the immune system , phospholipase C degrades the membrane of the phagosome before it can fuse with the lysosome , allowing the pathogen to escape into the cytoplasm and multiply .", "question": { "cloze_format": "Phospholipases are enzymes that ___.", "normal_format": "Phospholipases are enzymes that do which of the following?", "question_choices": [ "degrade antibodies", "promote pathogen spread through connective tissue.", "degrade nucleic acid to promote spread of pathogen", "degrade cell membranes to allow pathogens to escape phagosomes" ], "question_id": "fs-id1167583711017", "question_text": "Phospholipases are enzymes that do which of the following?" }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 1, "ans_text": "B" }, "bloom": null, "hl_context": "<hl> The main virulence factor for Cryptococcus , a fungus that causes pneumonia and meningitis , is capsule production . <hl> The polysaccharide glucuronoxylomannan is the principal constituent of the Cryptococcus capsule . Similar to encapsulated bacterial cells , encapsulated Cryptococcus cells are more resistant to phagocytosis than nonencapsulated Cryptococcus , which are effectively phagocytosed and , therefore , less virulent .", "hl_sentences": "The main virulence factor for Cryptococcus , a fungus that causes pneumonia and meningitis , is capsule production .", "question": { "cloze_format": "___ is a major virulence factor for the fungal pathogen Cryptococcus.", "normal_format": "Which of the following is a major virulence factor for the fungal pathogen Cryptococcus?", "question_choices": [ "hemolysin", "capsule", "collagenase", "fimbriae" ], "question_id": "fs-id1167584953385", "question_text": "Which of the following is a major virulence factor for the fungal pathogen Cryptococcus?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 2, "ans_text": "C" }, "bloom": null, "hl_context": "<hl> Some protozoans are capable of antigenic variation . <hl> <hl> The obligate intracellular pathogen Plasmodium falciparum ( one of the causative agents of malaria ) resides inside red blood cells , where it produces an adhesin membrane protein known as PfEMP 1 . <hl> This protein is expressed on the surface of the infected erythrocytes , causing blood cells to stick to each other and to the walls of blood vessels . This process impedes blood flow , sometimes leading to organ failure , anemia , jaundice ( yellowing of skin and sclera of the eyes due to buildup of bilirubin from lysed red blood cells ) , and , subsequently , death . Although PfEMP 1 can be recognized by the host ’ s immune system , antigenic variations in the structure of the protein over time prevent it from being easily recognized and eliminated . This allows malaria to persist as a chronic infection in many individuals . <hl> Protozoans often have unique features for attaching to host cells . <hl> The protozoan Giardia lamblia , which causes the intestinal disease giardiasis , uses a large adhesive disc composed of microtubules to attach to the intestinal mucosa . During adhesion , the flagella of G . lamblia move in a manner that draws fluid out from under the disc , resulting in an area of lower pressure that facilitates adhesion to epithelial cells . Giardia does not invade the intestinal cells but rather causes inflammation ( possibly through the release of cytopathic substances that cause damage to the cells ) and shortens the intestinal villi , inhibiting absorption of nutrients .", "hl_sentences": "Some protozoans are capable of antigenic variation . The obligate intracellular pathogen Plasmodium falciparum ( one of the causative agents of malaria ) resides inside red blood cells , where it produces an adhesin membrane protein known as PfEMP 1 . Protozoans often have unique features for attaching to host cells .", "question": { "cloze_format": "The pathogen that undergoes antigenic variation to avoid immune defenses is ___.", "normal_format": "Which of the following pathogens undergoes antigenic variation to avoid immune defenses?", "question_choices": [ "Candida", "Cryptococcus", "Plasmodium", "Giardia" ], "question_id": "fs-id1167583620629", "question_text": "Which of the following pathogens undergoes antigenic variation to avoid immune defenses?" }, "references_are_paraphrase": 0 } ]
15
15.1 Characteristics of Infectious Disease Learning Objectives Distinguish between signs and symptoms of disease Explain the difference between a communicable disease and a noncommunicable disease Compare different types of infectious diseases, including iatrogenic, nosocomial, and zoonotic diseases Identify and describe the stages of an acute infectious disease in terms of number of pathogens present and severity of signs and symptoms Clinical Focus Part 1 Michael, a 10-year-old boy in generally good health, went to a birthday party on Sunday with his family. He ate many different foods but was the only one in the family to eat the undercooked hot dogs served by the hosts. Monday morning, he woke up feeling achy and nauseous, and he was running a fever of 38 °C (100.4 °F). His parents, assuming Michael had caught the flu, made him stay home from school and limited his activities. But after 4 days, Michael began to experience severe headaches, and his fever spiked to 40 °C (104 °F). Growing worried, his parents finally decide to take Michael to a nearby clinic. What signs and symptoms is Michael experiencing? What do these signs and symptoms tell us about the stage of Michael’s disease? Jump to the next Clinical Focus box. A disease is any condition in which the normal structure or functions of the body are damaged or impaired. Physical injuries or disabilities are not classified as disease, but there can be several causes for disease, including infection by a pathogen, genetics (as in many cancers or deficiencies), noninfectious environmental causes, or inappropriate immune responses. Our focus in this chapter will be on infectious diseases, although when diagnosing infectious diseases, it is always important to consider possible noninfectious causes. Signs and Symptoms of Disease An infection is the successful colonization of a host by a microorganism. Infections can lead to disease, which causes signs and symptoms resulting in a deviation from the normal structure or functioning of the host. Microorganisms that can cause disease are known as pathogens. The sign s of disease are objective and measurable, and can be directly observed by a clinician. Vital signs, which are used to measure the body’s basic functions, include body temperature (normally 37 °C [98.6 °F]), heart rate (normally 60–100 beats per minute), breathing rate (normally 12–18 breaths per minute), and blood pressure (normally between 90/60 and 120/80 mm Hg). Changes in any of the body’s vital signs may be indicative of disease. For example, having a fever (a body temperature significantly higher than 37 °C or 98.6 °F) is a sign of disease because it can be measured. In addition to changes in vital signs, other observable conditions may be considered signs of disease. For example, the presence of antibodies in a patient’s serum (the liquid portion of blood that lacks clotting factors) can be observed and measured through blood tests and, therefore, can be considered a sign. However, it is important to note that the presence of antibodies is not always a sign of an active disease. Antibodies can remain in the body long after an infection has resolved; also, they may develop in response to a pathogen that is in the body but not currently causing disease. Unlike signs, symptom s of disease are subjective. Symptoms are felt or experienced by the patient, but they cannot be clinically confirmed or objectively measured. Examples of symptoms include nausea, loss of appetite, and pain. Such symptoms are important to consider when diagnosing disease, but they are subject to memory bias and are difficult to measure precisely. Some clinicians attempt to quantify symptoms by asking patients to assign a numerical value to their symptoms. For example, the Wong-Baker Faces pain-rating scale asks patients to rate their pain on a scale of 0–10. An alternative method of quantifying pain is measuring skin conductance fluctuations. These fluctuations reflect sweating due to skin sympathetic nerve activity resulting from the stressor of pain. 1 1 F. Savino et al. “Pain Assessment in Children Undergoing Venipuncture: The Wong–Baker Faces Scale Versus Skin Conductance Fluctuations.” PeerJ 1 (2013):e37; https://peerj.com/articles/37/ A specific group of signs and symptoms characteristic of a particular disease is called a syndrome . Many syndromes are named using a nomenclature based on signs and symptoms or the location of the disease. Table 15.1 lists some of the prefixes and suffixes commonly used in naming syndromes. Nomenclature of Symptoms Affix Meaning Example cyto- cell cytopenia: reduction in the number of blood cells hepat- of the liver hepatitis: inflammation of the liver -pathy disease neuropathy: a disease affecting nerves -emia of the blood bacteremia: presence of bacteria in blood -itis inflammation colitis: inflammation of the colon -lysis destruction hemolysis: destruction of red blood cells -oma tumor lymphoma: cancer of the lymphatic system -osis diseased or abnormal condition leukocytosis: abnormally high number of white blood cells -derma of the skin keratoderma: a thickening of the skin Table 15.1 Clinicians must rely on signs and on asking questions about symptoms, medical history, and the patient’s recent activities to identify a particular disease and the potential causative agent. Diagnosis is complicated by the fact that different microorganisms can cause similar signs and symptoms in a patient. For example, an individual presenting with symptoms of diarrhea may have been infected by one of a wide variety of pathogenic microorganisms. Bacterial pathogens associated with diarrheal disease include Vibrio cholerae , Listeria monocytogenes , Campylobacter jejuni , and enteropathogenic Escherichia coli ( EPEC ). Viral pathogens associated with diarrheal disease include norovirus and rotavirus. Parasitic pathogens associated with diarrhea include Giardia lamblia and Cryptosporidium parvum . Likewise, fever is indicative of many types of infection, from the common cold to the deadly Ebola hemorrhagic fever . Finally, some diseases may be asymptomatic or subclinical , meaning they do not present any noticeable signs or symptoms. For example, most individual infected with herpes simplex virus remain asymptomatic and are unaware that they have been infected. Check Your Understanding Explain the difference between signs and symptoms. Classifications of Disease The World Health Organization’s (WHO) International Classification of Diseases (ICD) is used in clinical fields to classify diseases and monitor morbidity (the number of cases of a disease) and mortality (the number of deaths due to a disease). In this section, we will introduce terminology used by the ICD (and in health-care professions in general) to describe and categorize various types of disease. An infectious disease is any disease caused by the direct effect of a pathogen. A pathogen may be cellular (bacteria, parasites, and fungi) or acellular (viruses, viroids, and prions). Some infectious diseases are also communicable , meaning they are capable of being spread from person to person through either direct or indirect mechanisms. Some infectious communicable diseases are also considered contagious diseases, meaning they are easily spread from person to person. Not all contagious diseases are equally so; the degree to which a disease is contagious usually depends on how the pathogen is transmitted. For example, measles is a highly contagious viral disease that can be transmitted when an infected person coughs or sneezes and an uninfected person breathes in droplets containing the virus. Gonorrhea is not as contagious as measles because transmission of the pathogen ( Neisseria gonorrhoeae ) requires close intimate contact (usually sexual) between an infected person and an uninfected person. Diseases that are contracted as the result of a medical procedure are known as iatrogenic disease s . Iatrogenic diseases can occur after procedures involving wound treatments, catheterization, or surgery if the wound or surgical site becomes contaminated. For example, an individual treated for a skin wound might acquire necrotizing fasciitis (an aggressive, “flesh-eating” disease) if bandages or other dressings became contaminated by Clostridium perfringens or one of several other bacteria that can cause this condition. Diseases acquired in hospital settings are known as nosocomial disease s . Several factors contribute to the prevalence and severity of nosocomial diseases. First, sick patients bring numerous pathogens into hospitals, and some of these pathogens can be transmitted easily via improperly sterilized medical equipment, bed sheets, call buttons, door handles, or by clinicians, nurses, or therapists who do not wash their hands before touching a patient. Second, many hospital patients have weakened immune systems, making them more susceptible to infections. Compounding this, the prevalence of antibiotics in hospital settings can select for drug-resistant bacteria that can cause very serious infections that are difficult to treat. Certain infectious diseases are not transmitted between humans directly but can be transmitted from animals to humans. Such a disease is called zoonotic disease (or zoonosis ). According to WHO, a zoonosis is a disease that occurs when a pathogen is transferred from a vertebrate animal to a human; however, sometimes the term is defined more broadly to include diseases transmitted by all animals (including invertebrates). For example, rabies is a viral zoonotic disease spread from animals to humans through bites and contact with infected saliva. Many other zoonotic diseases rely on insects or other arthropods for transmission. Examples include yellow fever (transmitted through the bite of mosquitoes infected with yellow fever virus) and Rocky Mountain spotted fever (transmitted through the bite of ticks infected with Rickettsia rickettsii ). In contrast to communicable infectious diseases, a noncommunicable infectious disease is not spread from one person to another. One example is tetanus , caused by Clostridium tetani , a bacterium that produces endospores that can survive in the soil for many years. This disease is typically only transmitted through contact with a skin wound; it cannot be passed from an infected person to another person. Similarly, Legionnaires disease is caused by Legionella pneumophila , a bacterium that lives within amoebae in moist locations like water-cooling towers. An individual may contract Legionnaires disease via contact with the contaminated water, but once infected, the individual cannot pass the pathogen to other individuals. In addition to the wide variety of noncommunicable infectious diseases, noninfectious disease s (those not caused by pathogens) are an important cause of morbidity and mortality worldwide. Noninfectious diseases can be caused by a wide variety factors, including genetics, the environment, or immune system dysfunction, to name a few. For example, sickle cell anemia is an inherited disease caused by a genetic mutation that can be passed from parent to offspring ( Figure 15.2 ). Other types of noninfectious diseases are listed in Table 15.2 . Types of Noninfectious Diseases Type Definition Example Inherited A genetic disease Sickle cell anemia Congenital Disease that is present at or before birth Down syndrome Degenerative Progressive, irreversible loss of function Parkinson disease (affecting central nervous system) Nutritional deficiency Impaired body function due to lack of nutrients Scurvy (vitamin C deficiency) Endocrine Disease involving malfunction of glands that release hormones to regulate body functions Hypothyroidism – thyroid does not produce enough thyroid hormone, which is important for metabolism Neoplastic Abnormal growth (benign or malignant) Some forms of cancer Idiopathic Disease for which the cause is unknown Idiopathic juxtafoveal retinal telangiectasia (dilated, twisted blood vessels in the retina of the eye) Table 15.2 Link to Learning Lists of common infectious diseases can be found at the following Centers for Disease Control and Prevention (CDC), World Health Organization (WHO), and International Classification of Diseases websites. Check Your Understanding Describe how a disease can be infectious but not contagious. Explain the difference between iatrogenic disease and nosocomial disease. Periods of Disease The five periods of disease (sometimes referred to as stages or phases) include the incubation, prodromal, illness, decline, and convalescence periods ( Figure 15.3 ). The incubation period occurs in an acute disease after the initial entry of the pathogen into the host (patient). It is during this time the pathogen begins multiplying in the host. However, there are insufficient numbers of pathogen particles (cells or viruses) present to cause signs and symptoms of disease. Incubation periods can vary from a day or two in acute disease to months or years in chronic disease, depending upon the pathogen. Factors involved in determining the length of the incubation period are diverse, and can include strength of the pathogen, strength of the host immune defenses, site of infection, type of infection, and the size infectious dose received. During this incubation period, the patient is unaware that a disease is beginning to develop. The prodromal period occurs after the incubation period. During this phase, the pathogen continues to multiply and the host begins to experience general signs and symptoms of illness, which typically result from activation of the immune system, such as fever, pain, soreness, swelling, or inflammation. Usually, such signs and symptoms are too general to indicate a particular disease. Following the prodromal period is the period of illness , during which the signs and symptoms of disease are most obvious and severe. The period of illness is followed by the period of decline , during which the number of pathogen particles begins to decrease, and the signs and symptoms of illness begin to decline. However, during the decline period, patients may become susceptible to developing secondary infections because their immune systems have been weakened by the primary infection. The final period is known as the period of convalescence . During this stage, the patient generally returns to normal functions, although some diseases may inflict permanent damage that the body cannot fully repair. Infectious diseases can be contagious during all five of the periods of disease. Which periods of disease are more likely to associated with transmissibility of an infection depends upon the disease, the pathogen, and the mechanisms by which the disease develops and progresses. For example, with meningitis (infection of the lining of brain), the periods of infectivity depend on the type of pathogen causing the infection. Patients with bacterial meningitis are contagious during the incubation period for up to a week before the onset of the prodromal period, whereas patients with viral meningitis become contagious when the first signs and symptoms of the prodromal period appear. With many viral diseases associated with rashes (e.g., chickenpox , measles , rubella , roseola ), patients are contagious during the incubation period up to a week before the rash develops. In contrast, with many respiratory infections (e.g., colds, influenza , diphtheria , strep throat , and pertussis ) the patient becomes contagious with the onset of the prodromal period. Depending upon the pathogen, the disease, and the individual infected, transmission can still occur during the periods of decline, convalescence, and even long after signs and symptoms of the disease disappear. For example, an individual recovering from a diarrheal disease may continue to carry and shed the pathogen in feces for some time, posing a risk of transmission to others through direct contact or indirect contact (e.g., through contaminated objects or food). Check Your Understanding Name some of the factors that can affect the length of the incubation period of a particular disease. Acute and Chronic Diseases The duration of the period of illness can vary greatly, depending on the pathogen, effectiveness of the immune response in the host, and any medical treatment received. For an acute disease , pathologic changes occur over a relatively short time (e.g., hours, days, or a few weeks) and involve a rapid onset of disease conditions. For example, influenza (caused by Influenzavirus) is considered an acute disease because the incubation period is approximately 1–2 days. Infected individuals can spread influenza to others for approximately 5 days after becoming ill. After approximately 1 week, individuals enter the period of decline. For a chronic disease , pathologic changes can occur over longer time spans (e.g., months, years, or a lifetime). For example, chronic gastritis (inflammation of the lining of the stomach) is caused by the gram-negative bacterium Helicobacter pylori . H. pylori is able to colonize the stomach and persist in its highly acidic environment by producing the enzyme urease, which modifies the local acidity, allowing the bacteria to survive indefinitely. 2 Consequently, H. pylori infections can recur indefinitely unless the infection is cleared using antibiotics. 3 Hepatitis B virus can cause a chronic infection in some patients who do not eliminate the virus after the acute illness. A chronic infection with hepatitis B virus is characterized by the continued production of infectious virus for 6 months or longer after the acute infection, as measured by the presence of viral antigen in blood samples. 2 J.G. Kusters et al. Pathogenesis of Helicobacter pylori Infection. Clinical Microbiology Reviews 19 no. 3 (2006):449–490. 3 N.R. Salama et al. “Life in the Human Stomach: Persistence Strategies of the Bacterial Pathogen Helicobacter pylori .” Nature Reviews Microbiology 11 (2013):385–399. In latent disease s , as opposed to chronic infections, the causal pathogen goes dormant for extended periods of time with no active replication. Examples of diseases that go into a latent state after the acute infection include herpes (herpes simplex viruses [HSV-1 and HSV-2]), chickenpox ( varicella-zoster virus [VZV]), and mononucleosis ( Epstein-Barr virus [EBV]). HSV-1, HSV-2, and VZV evade the host immune system by residing in a latent form within cells of the nervous system for long periods of time, but they can reactivate to become active infections during times of stress and immunosuppression. For example, an initial infection by VZV may result in a case of childhood chickenpox, followed by a long period of latency. The virus may reactivate decades later, causing episodes of shingles in adulthood. EBV goes into latency in B cells of the immune system and possibly epithelial cells; it can reactivate years later to produce B-cell lymphoma. Check Your Understanding Explain the difference between latent disease and chronic disease. 15.2 How Pathogens Cause Disease Learning Objectives Summarize Koch’s postulates and molecular Koch’s postulates, respectively, and explain their significance and limitations Explain the concept of pathogenicity (virulence) in terms of infectious and lethal dose Distinguish between primary and opportunistic pathogens and identify specific examples of each Summarize the stages of pathogenesis Explain the roles of portals of entry and exit in the transmission of disease and identify specific examples of these portals For most infectious diseases, the ability to accurately identify the causative pathogen is a critical step in finding or prescribing effective treatments. Today’s physicians, patients, and researchers owe a sizable debt to the physician Robert Koch (1843–1910), who devised a systematic approach for confirming causative relationships between diseases and specific pathogens. Koch’s Postulates In 1884, Koch published four postulates ( Table 15.3 ) that summarized his method for determining whether a particular microorganism was the cause of a particular disease. Each of Koch’s postulates represents a criterion that must be met before a disease can be positively linked with a pathogen. In order to determine whether the criteria are met, tests are performed on laboratory animals and cultures from healthy and diseased animals are compared ( Figure 15.4 ). Koch’s Postulates (1) The suspected pathogen must be found in every case of disease and not be found in healthy individuals. (2) The suspected pathogen can be isolated and grown in pure culture. (3) A healthy test subject infected with the suspected pathogen must develop the same signs and symptoms of disease as seen in postulate 1. (4) The pathogen must be re-isolated from the new host and must be identical to the pathogen from postulate 2. Table 15.3 In many ways, Koch’s postulates are still central to our current understanding of the causes of disease. However, advances in microbiology have revealed some important limitations in Koch’s criteria. Koch made several assumptions that we now know are untrue in many cases. The first relates to postulate 1, which assumes that pathogens are only found in diseased, not healthy, individuals. This is not true for many pathogens. For example, H. pylori , described earlier in this chapter as a pathogen causing chronic gastritis, is also part of the normal microbiota of the stomach in many healthy humans who never develop gastritis. It is estimated that upwards of 50% of the human population acquires H. pylori early in life, with most maintaining it as part of the normal microbiota for the rest of their life without ever developing disease. Koch’s second faulty assumption was that all healthy test subjects are equally susceptible to disease. We now know that individuals are not equally susceptible to disease. Individuals are unique in terms of their microbiota and the state of their immune system at any given time. The makeup of the resident microbiota can influence an individual’s susceptibility to an infection. Members of the normal microbiota play an important role in immunity by inhibiting the growth of transient pathogens. In some cases, the microbiota may prevent a pathogen from establishing an infection; in others, it may not prevent an infection altogether but may influence the severity or type of signs and symptoms. As a result, two individuals with the same disease may not always present with the same signs and symptoms. In addition, some individuals have stronger immune systems than others. Individuals with immune systems weakened by age or an unrelated illness are much more susceptible to certain infections than individuals with strong immune systems. Koch also assumed that all pathogens are microorganisms that can be grown in pure culture (postulate 2) and that animals could serve as reliable models for human disease. However, we now know that not all pathogens can be grown in pure culture, and many human diseases cannot be reliably replicated in animal hosts. Viruses and certain bacteria, including Rickettsia and Chlamydia , are obligate intracellular pathogens that can grow only when inside a host cell. If a microbe cannot be cultured, a researcher cannot move past postulate 2. Likewise, without a suitable nonhuman host, a researcher cannot evaluate postulate 2 without deliberately infecting humans, which presents obvious ethical concerns. AIDS is an example of such a disease because the human immunodeficiency virus (HIV) only causes disease in humans. Check Your Understanding Briefly summarize the limitations of Koch’s postulates. Molecular Koch’s Postulates In 1988, Stanley Falkow (1934–) proposed a revised form of Koch’s postulates known as molecular Koch’s postulates . These are listed in the left column of Table 15.4 . The premise for molecular Koch’s postulates is not in the ability to isolate a particular pathogen but rather to identify a gene that may cause the organism to be pathogenic. Falkow’s modifications to Koch’s original postulates explain not only infections caused by intracellular pathogens but also the existence of pathogenic strains of organisms that are usually nonpathogenic. For example, the predominant form of the bacterium Escherichia coli is a member of the normal microbiota of the human intestine and is generally considered harmless. However, there are pathogenic strains of E. coli such as enterotoxigenic E. coli ( ETEC ) and enterohemorrhagic E. coli (O157:H7) (EHEC). We now know ETEC and EHEC exist because of the acquisition of new genes by the once-harmless E. coli , which, in the form of these pathogenic strains, is now capable of producing toxins and causing illness. The pathogenic forms resulted from minor genetic changes. The right-side column of Table 15.4 illustrates how molecular Koch’s postulates can be applied to identify EHEC as a pathogenic bacterium. Molecular Koch’s Postulates Applied to EHEC Molecular Koch’s Postulates Application to EHEC (1) The phenotype (sign or symptom of disease) should be associated only with pathogenic strains of a species. EHEC causes intestinal inflammation and diarrhea, whereas nonpathogenic strains of E. coli do not. (2) Inactivation of the suspected gene(s) associated with pathogenicity should result in a measurable loss of pathogenicity. One of the genes in EHEC encodes for Shiga toxin, a bacterial toxin (poison) that inhibits protein synthesis. Inactivating this gene reduces the bacteria’s ability to cause disease. (3) Reversion of the inactive gene should restore the disease phenotype. By adding the gene that encodes the toxin back into the genome (e.g., with a phage or plasmid), EHEC’s ability to cause disease is restored. Table 15.4 As with Koch’s original postulates, the molecular Koch’s postulates have limitations. For example, genetic manipulation of some pathogens is not possible using current methods of molecular genetics. In a similar vein, some diseases do not have suitable animal models, which limits the utility of both the original and molecular postulates. Check Your Understanding Explain the differences between Koch’s original postulates and the molecular Koch’s postulates. Pathogenicity and Virulence The ability of a microbial agent to cause disease is called pathogenicity , and the degree to which an organism is pathogenic is called virulence . Virulence is a continuum. On one end of the spectrum are organisms that are avirulent (not harmful) and on the other are organisms that are highly virulent. Highly virulent pathogens will almost always lead to a disease state when introduced to the body, and some may even cause multi-organ and body system failure in healthy individuals. Less virulent pathogens may cause an initial infection, but may not always cause severe illness. Pathogens with low virulence would more likely result in mild signs and symptoms of disease, such as low-grade fever, headache, or muscle aches. Some individuals might even be asymptomatic. An example of a highly virulent microorganism is Bacillus anthracis , the pathogen responsible for anthrax . B. anthracis can produce different forms of disease, depending on the route of transmission (e.g., cutaneous injection, inhalation, ingestion). The most serious form of anthrax is inhalation anthrax. After B. anthracis spores are inhaled, they germinate. An active infection develops and the bacteria release potent toxins that cause edema (fluid buildup in tissues), hypoxia (a condition preventing oxygen from reaching tissues), and necrosis (cell death and inflammation). Signs and symptoms of inhalation anthrax include high fever, difficulty breathing, vomiting and coughing up blood, and severe chest pains suggestive of a heart attack. With inhalation anthrax, the toxins and bacteria enter the bloodstream, which can lead to multi-organ failure and death of the patient. If a gene (or genes) involved in pathogenesis is inactivated, the bacteria become less virulent or nonpathogenic. Virulence of a pathogen can be quantified using controlled experiments with laboratory animals. Two important indicators of virulence are the median infectious dose (ID 50 ) and the median lethal dose (LD 50 ) , both of which are typically determined experimentally using animal models. The ID 50 is the number of pathogen cells or virions required to cause active infection in 50% of inoculated animals. The LD 50 is the number of pathogenic cells, virions, or amount of toxin required to kill 50% of infected animals. To calculate these values, each group of animals is inoculated with one of a range of known numbers of pathogen cells or virions. In graphs like the one shown in Figure 15.5 , the percentage of animals that have been infected (for ID 50 ) or killed (for LD 50 ) is plotted against the concentration of pathogen inoculated. Figure 15.5 represents data graphed from a hypothetical experiment measuring the LD 50 of a pathogen. Interpretation of the data from this graph indicates that the LD 50 of the pathogen for the test animals is 10 4 pathogen cells or virions (depending upon the pathogen studied). Table 15.5 lists selected foodborne pathogens and their ID 50 values in humans (as determined from epidemiologic data and studies on human volunteers). Keep in mind that these are median values. The actual infective dose for an individual can vary widely, depending on factors such as route of entry; the age, health, and immune status of the host; and environmental and pathogen-specific factors such as susceptibility to the acidic pH of the stomach. It is also important to note that a pathogen’s infective dose does not necessarily correlate with disease severity. For example, just a single cell of Salmonella enterica serotype Typhimurium can result in an active infection. The resultant disease, Salmonella gastroenteritis or salmonellosis , can cause nausea, vomiting, and diarrhea, but has a mortality rate of less than 1% in healthy adults. In contrast, S. enterica serotype Typhi has a much higher ID 50 , typically requiring as many as 1,000 cells to produce infection. However, this serotype causes typhoid fever , a much more systemic and severe disease that has a mortality rate as high as 10% in untreated individuals. ID 50 for Selected Foodborne Diseases 4 4 Food and Drug Administration. “Bad Bug Book, Foodborne Pathogenic Microorganisms and Natural Toxins.” 2nd ed. Silver Spring, MD: US Food and Drug Administration; 2012. Pathogen ID 50 Viruses Hepatitis A virus 10–100 Norovirus 1–10 Rotavirus 10–100 Bacteria Escherichia coli , enterohemorrhagic (EHEC, serotype O157) 10–100 E. coli , enteroinvasive (EIEC) 200–5,000 E. coli , enteropathogenic (EPEC) 10,000,000–10,000,000,000 E. coli , enterotoxigenic (ETEC) 10,000,000–10,000,000,000 Salmonella enterica serovar Typhi <1,000 S. enterica serovar Typhimurium ≥1 Shigella dysenteriae 10–200 Vibrio cholerae (serotypes O139, O1) 1,000,000 V. parahemolyticus 100,000,000 Protozoa Giardia lamblia 1 Cryptosporidium parvum 10–100 Table 15.5 Check Your Understanding What is the difference between a pathogen’s infective dose and lethal dose? Which is more closely related to the severity of a disease? Primary Pathogens versus Opportunistic Pathogens Pathogens can be classified as either primary pathogens or opportunistic pathogens. A primary pathogen can cause disease in a host regardless of the host’s resident microbiota or immune system. An opportunistic pathogen , by contrast, can only cause disease in situations that compromise the host’s defenses, such as the body’s protective barriers, immune system, or normal microbiota. Individuals susceptible to opportunistic infections include the very young, the elderly, women who are pregnant, patients undergoing chemotherapy, people with immunodeficiencies (such as acquired immunodeficiency syndrome [AIDS]), patients who are recovering from surgery, and those who have had a breach of protective barriers (such as a severe wound or burn). An example of a primary pathogen is enterohemorrhagic E. coli ( EHEC ), which produces a virulence factor known as Shiga toxin . This toxin inhibits protein synthesis, leading to severe and bloody diarrhea, inflammation, and renal failure, even in patients with healthy immune systems. Staphylococcus epidermidis , on the other hand, is an opportunistic pathogen that is among the most frequent causes of nosocomial disease. 5 S. epidermidis is a member of the normal microbiota of the skin, where it is generally avirulent. However, in hospitals, it can also grow in biofilms that form on catheters, implants, or other devices that are inserted into the body during surgical procedures. Once inside the body, S. epidermidis can cause serious infections such as endocarditis, and it produces virulence factors that promote the persistence of such infections. 5 M. Otto. “ Staphylococcus epidermidis --The ‘Accidental’ Pathogen.” Nature Reviews Microbiology 7 no. 8 (2009):555–567. Other members of the normal microbiota can also cause opportunistic infections under certain conditions. This often occurs when microbes that reside harmlessly in one body location end up in a different body system, where they cause disease. For example, E. coli normally found in the large intestine can cause a urinary tract infection if it enters the bladder. This is the leading cause of urinary tract infections among women. Members of the normal microbiota may also cause disease when a shift in the environment of the body leads to overgrowth of a particular microorganism. For example, the yeast Candida is part of the normal microbiota of the skin, mouth, intestine, and vagina, but its population is kept in check by other organisms of the microbiota. If an individual is taking antibacterial medications, however, bacteria that would normally inhibit the growth of Candida can be killed off, leading to a sudden growth in the population of Candida , which is not affected by antibacterial medications because it is a fungus. An overgrowth of Candida can manifest as oral thrush (growth on mouth, throat, and tongue), a vaginal yeast infection , or cutaneous candidiasis . Other scenarios can also provide opportunities for Candida infections. Untreated diabetes can result in a high concentration of glucose in the saliva, which provides an optimal environment for the growth of Candida, resulting in thrush. Immunodeficiencies such as those seen in patients with HIV, AIDS, and cancer also lead to higher incidence of thrush. Vaginal yeast infections can result from decreases in estrogen levels during the menstruation or menopause. The amount of glycogen available to lactobacilli in the vagina is controlled by levels of estrogen; when estrogen levels are low, lactobacilli produce less lactic acid. The resultant increase in vaginal pH allows overgrowth of Candida in the vagina. Check Your Understanding Explain the difference between a primary pathogen and an opportunistic pathogen. Describe some conditions under which an opportunistic infection can occur. Stages of Pathogenesis To cause disease, a pathogen must successfully achieve four steps or stages of pathogenesis : exposure (contact), adhesion (colonization), invasion, and infection. The pathogen must be able to gain entry to the host, travel to the location where it can establish an infection, evade or overcome the host’s immune response, and cause damage (i.e., disease) to the host. In many cases, the cycle is completed when the pathogen exits the host and is transmitted to a new host. Exposure An encounter with a potential pathogen is known as exposure or contact . The food we eat and the objects we handle are all ways that we can come into contact with potential pathogens. Yet, not all contacts result in infection and disease. For a pathogen to cause disease, it needs to be able to gain access into host tissue. An anatomic site through which pathogens can pass into host tissue is called a portal of entry . These are locations where the host cells are in direct contact with the external environment. Major portals of entry are identified in Figure 15.6 and include the skin, mucous membranes, and parenteral routes. Mucosal surfaces are the most important portals of entry for microbes; these include the mucous membranes of the respiratory tract, the gastrointestinal tract, and the genitourinary tract. Although most mucosal surfaces are in the interior of the body, some are contiguous with the external skin at various body openings, including the eyes, nose, mouth, urethra, and anus. Most pathogens are suited to a particular portal of entry. A pathogen’s portal specificity is determined by the organism’s environmental adaptions and by the enzymes and toxins they secrete. The respiratory and gastrointestinal tracts are particularly vulnerable portals of entry because particles that include microorganisms are constantly inhaled or ingested, respectively. Pathogens can also enter through a breach in the protective barriers of the skin and mucous membranes. Pathogens that enter the body in this way are said to enter by the parenteral route . For example, the skin is a good natural barrier to pathogens, but breaks in the skin (e.g., wounds, insect bites, animal bites, needle pricks) can provide a parenteral portal of entry for microorganisms. In pregnant women, the placenta normally prevents microorganisms from passing from the mother to the fetus. However, a few pathogens are capable of crossing the blood-placental barrier. The gram-positive bacterium Listeria monocytogenes , which causes the foodborne disease listeriosis, is one example that poses a serious risk to the fetus and can sometimes lead to spontaneous abortion. Other pathogens that can pass the placental barrier to infect the fetus are known collectively by the acronym TORCH ( Table 15.6 ). Transmission of infectious diseases from mother to baby is also a concern at the time of birth when the baby passes through the birth canal. Babies whose mothers have active chlamydia or gonorrhea infections may be exposed to the causative pathogens in the vagina, which can result in eye infections that lead to blindness. To prevent this, it is standard practice to administer antibiotic drops to infants’ eyes shortly after birth. Pathogens Capable of Crossing the Placental Barrier (TORCH Infections)   Disease Pathogen T Toxoplasmosis Toxoplasma gondii (protozoan) O 6 6 The O in TORCH stands for “other.” Syphilis Chickenpox Hepatitis B HIV Fifth disease (erythema infectiosum) Treponema pallidum (bacterium) Varicella-zoster virus (human herpesvirus 3) Hepatitis B virus (hepadnavirus) Retrovirus Parvovirus B19 R Rubella (German measles) Togavirus C Cytomegalovirus Human herpesvirus 5 H Herpes Herpes simplex viruses (HSV) 1 and 2 Table 15.6 Clinical Focus Part 2 At the clinic, a physician takes down Michael’s medical history and asks about his activities and diet over the past week. Upon learning that Michael became sick the day after the party, the physician orders a blood test to check for pathogens associated with foodborne diseases. After tests confirm that presence of a gram-positive rod in Michael’s blood, he is given an injection of a broad-spectrum antibiotic and sent to a nearby hospital, where he is admitted as a patient. There he is to receive additional intravenous antibiotic therapy and fluids. Is this bacterium in Michael’s blood part of normal microbiota? What portal of entry did the bacteria use to cause this infection? Jump to the next Clinical Focus box. Go back to the previous Clinical Focus box. Adhesion Following the initial exposure, the pathogen adheres at the portal of entry. The term adhesion refers to the capability of pathogenic microbes to attach to the cells of the body using adhesion factors , and different pathogens use various mechanisms to adhere to the cells of host tissues. Molecules (either proteins or carbohydrates) called adhesins are found on the surface of certain pathogens and bind to specific receptors (glycoproteins) on host cells. Adhesins are present on the fimbriae and flagella of bacteria, the cilia of protozoa, and the capsids or membranes of viruses. Protozoans can also use hooks and barbs for adhesion; spike proteins on viruses also enhance viral adhesion. The production of glycocalyces (slime layers and capsules) ( Figure 15.7 ), with their high sugar and protein content, can also allow certain bacterial pathogens to attach to cells. Biofilm growth can also act as an adhesion factor. A biofilm is a community of bacteria that produce a glycocalyx, known as extrapolymeric substance (EPS) , that allows the biofilm to attach to a surface. Persistent Pseudomonas aeruginosa infections are common in patients suffering from cystic fibrosis, burn wounds, and middle-ear infections (otitis media) because P. aeruginosa produces a biofilm. The EPS allows the bacteria to adhere to the host cells and makes it harder for the host to physically remove the pathogen. The EPS not only allows for attachment but provides protection against the immune system and antibiotic treatments, preventing antibiotics from reaching the bacterial cells within the biofilm. In addition, not all bacteria in a biofilm are rapidly growing; some are in stationary phase. Since antibiotics are most effective against rapidly growing bacteria, portions of bacteria in a biofilm are protected against antibiotics. 7 7 D. Davies. “Understanding Biofilm Resistance to Antibacterial Agents.” Nature Reviews Drug Discovery 2 (2003):114–122. Invasion Once adhesion is successful, invasion can proceed. Invasion involves the dissemination of a pathogen throughout local tissues or the body. Pathogens may produce exoenzymes or toxins, which serve as virulence factors that allow them to colonize and damage host tissues as they spread deeper into the body. Pathogens may also produce virulence factors that protect them against immune system defenses. A pathogen’s specific virulence factors determine the degree of tissue damage that occurs. Figure 15.8 shows the invasion of H. pylori into the tissues of the stomach, causing damage as it progresses. Intracellular pathogens achieve invasion by entering the host’s cells and reproducing. Some are obligate intracellular pathogens (meaning they can only reproduce inside of host cells) and others are facultative intracellular pathogens (meaning they can reproduce either inside or outside of host cells). By entering the host cells, intracellular pathogens are able to evade some mechanisms of the immune system while also exploiting the nutrients in the host cell. Entry to a cell can occur by endocytosis . For most kinds of host cells, pathogens use one of two different mechanisms for endocytosis and entry. One mechanism relies on effector proteins secreted by the pathogen; these effector proteins trigger entry into the host cell. This is the method that Salmonella and Shigella use when invading intestinal epithelial cells. When these pathogens come in contact with epithelial cells in the intestine, they secrete effector molecules that cause protrusions of membrane ruffles that bring the bacterial cell in. This process is called membrane ruffling . The second mechanism relies on surface proteins expressed on the pathogen that bind to receptors on the host cell, resulting in entry. For example, Yersinia pseudotuberculosis produces a surface protein known as invasin that binds to beta-1 integrins expressed on the surface of host cells. Some host cells, such as white blood cells and other phagocytes of the immune system, actively endocytose pathogens in a process called phagocytosis. Although phagocytosis allows the pathogen to gain entry to the host cell, in most cases, the host cell kills and degrades the pathogen by using digestive enzymes. Normally, when a pathogen is ingested by a phagocyte, it is enclosed within a phagosome in the cytoplasm; the phagosome fuses with a lysosome to form a phagolysosome, where digestive enzymes kill the pathogen (see Pathogen Recognition and Phagocytosis ). However, some intracellular pathogens have the ability to survive and multiply within phagocytes. Examples include Listeria monocytogenes and Shigella ; these bacteria produce proteins that lyse the phagosome before it fuses with the lysosome, allowing the bacteria to escape into the phagocyte’s cytoplasm where they can multiply. Bacteria such as Mycobacterium tuberculosis , Legionella pneumophila , and Salmonella species use a slightly different mechanism to evade being digested by the phagocyte. These bacteria prevent the fusion of the phagosome with the lysosome, thus remaining alive and dividing within the phagosome. Infection Following invasion, successful multiplication of the pathogen leads to infection. Infections can be described as local, focal, or systemic, depending on the extent of the infection. A local infection is confined to a small area of the body, typically near the portal of entry. For example, a hair follicle infected by Staphylococcus aureus infection may result in a boil around the site of infection, but the bacterium is largely contained to this small location. Other examples of local infections that involve more extensive tissue involvement include urinary tract infections confined to the bladder or pneumonia confined to the lungs. In a focal infection , a localized pathogen, or the toxins it produces, can spread to a secondary location. For example, a dental hygienist nicking the gum with a sharp tool can lead to a local infection in the gum by Streptococcus bacteria of the normal oral microbiota. These Streptococcus spp. may then gain access to the bloodstream and make their way to other locations in the body, resulting in a secondary infection. When an infection becomes disseminated throughout the body, we call it a systemic infection . For example, infection by the varicella-zoster virus typically gains entry through a mucous membrane of the upper respiratory system. It then spreads throughout the body, resulting in the classic red skin lesions associated with chickenpox . Since these lesions are not sites of initial infection, they are signs of a systemic infection. Sometimes a primary infection , the initial infection caused by one pathogen, can lead to a secondary infection by another pathogen. For example, the immune system of a patient with a primary infection by HIV becomes compromised, making the patient more susceptible to secondary diseases like oral thrush and others caused by opportunistic pathogens. Similarly, a primary infection by Influenzavirus damages and decreases the defense mechanisms of the lungs, making patients more susceptible to a secondary pneumonia by a bacterial pathogen like Haemophilus influenzae or Streptococcus pneumoniae . Some secondary infections can even develop as a result of treatment for a primary infection. Antibiotic therapy targeting the primary pathogen can cause collateral damage to the normal microbiota, creating an opening for opportunistic pathogens (see Case in Point: A Secondary Yeast Infection ). Case in Point A Secondary Yeast Infection Anita, a 36-year-old mother of three, goes to an urgent care center complaining of pelvic pressure, frequent and painful urination, abdominal cramps, and occasional blood-tinged urine. Suspecting a urinary tract infection (UTI) , the physician requests a urine sample and sends it to the lab for a urinalysis. Since it will take approximately 24 hours to get the results of the culturing, the physician immediately starts Anita on the antibiotic ciprofloxacin. The next day, the microbiology lab confirms the presence of E. coli in Anita’s urine, which is consistent with the presumptive diagnosis. However, the antimicrobial susceptibility test indicates that ciprofloxacin would not effectively treat Anita’s UTI, so the physician prescribes a different antibiotic. After taking her antibiotics for 1 week, Anita returns to the clinic complaining that the prescription is not working. Although the painful urination has subsided, she is now experiencing vaginal itching, burning, and discharge. After a brief examination, the physician explains to Anita that the antibiotics were likely successful in killing the E. coli responsible for her UTI; however, in the process, they also wiped out many of the “good” bacteria in Anita’s normal microbiota. The new symptoms that Anita has reported are consistent with a secondary yeast infection by Candida albicans , an opportunistic fungus that normally resides in the vagina but is inhibited by the bacteria that normally reside in the same environment. To confirm this diagnosis, a microscope slide of a direct vaginal smear is prepared from the discharge to check for the presence of yeast. A sample of the discharge accompanies this slide to the microbiology lab to determine if there has been an increase in the population of yeast causing vaginitis. After the microbiology lab confirms the diagnosis, the physician prescribes an antifungal drug for Anita to use to eliminate her secondary yeast infection. Why was Candida not killed by the antibiotics prescribed for the UTI? Check Your Understanding List three conditions that could lead to a secondary infection. Transmission of Disease For a pathogen to persist, it must put itself in a position to be transmitted to a new host, leaving the infected host through a portal of exit ( Figure 15.9 ). As with portals of entry, many pathogens are adapted to use a particular portal of exit. Similar to portals of entry, the most common portals of exit include the skin and the respiratory, urogenital, and gastrointestinal tracts. Coughing and sneezing can expel pathogens from the respiratory tract. A single sneeze can send thousands of virus particles into the air. Secretions and excretions can transport pathogens out of other portals of exit. Feces, urine, semen, vaginal secretions, tears, sweat, and shed skin cells can all serve as vehicles for a pathogen to leave the body. Pathogens that rely on insect vectors for transmission exit the body in the blood extracted by a biting insect. Similarly, some pathogens exit the body in blood extracted by needles. 15.3 Virulence Factors of Bacterial and Viral Pathogens Learning Objectives Explain how virulence factors contribute to signs and symptoms of infectious disease Differentiate between endotoxins and exotoxins Describe and differentiate between various types of exotoxins Describe the mechanisms viruses use for adhesion and antigenic variation In the previous section, we explained that some pathogens are more virulent than others. This is due to the unique virulence factor s produced by individual pathogens, which determine the extent and severity of disease they may cause. A pathogen’s virulence factors are encoded by genes that can be identified using molecular Koch’s postulates. When genes encoding virulence factors are inactivated, virulence in the pathogen is diminished. In this section, we examine various types and specific examples of virulence factors and how they contribute to each step of pathogenesis. Virulence Factors for Adhesion As discussed in the previous section, the first two steps in pathogenesis are exposure and adhesion. Recall that an adhesin is a protein or glycoprotein found on the surface of a pathogen that attaches to receptors on the host cell. Adhesins are found on bacterial, viral, fungal, and protozoan pathogens. One example of a bacterial adhesin is type 1 fimbrial adhesin , a molecule found on the tips of fimbriae of enterotoxigenic E. coli ( ETEC ). Recall that fimbriae are hairlike protein bristles on the cell surface. Type 1 fimbrial adhesin allows the fimbriae of ETEC cells to attach to the mannose glycans expressed on intestinal epithelial cells. Table 15.7 lists common adhesins found in some of the pathogens we have discussed or will be seeing later in this chapter. Some Bacterial Adhesins and Their Host Attachment Sites Pathogen Disease Adhesin Attachment Site Streptococcus pyogenes Strep throat Protein F Respiratory epithelial cells Streptococcus mutans Dental caries Adhesin P1 Teeth Neisseria gonorrhoeae Gonorrhea Type IV pili Urethral epithelial cells Enterotoxigenic E. coli (ETEC) Traveler’s diarrhea Type 1 fimbriae Intestinal epithelial cells Vibrio cholerae Cholera N-methylphenylalanine pili Intestinal epithelial cells Table 15.7 Clinical Focus Part 3 The presence of bacteria in Michael’s blood is a sign of infection, since blood is normally sterile. There is no indication that the bacteria entered the blood through an injury. Instead, it appears the portal of entry was the gastrointestinal route. Based on Michael’s symptoms, the results of his blood test, and the fact that Michael was the only one in the family to partake of the hot dogs, the physician suspects that Michael is suffering from a case of listeriosis. Listeria monocytogenes , the facultative intracellular pathogen that causes listeriosis, is a common contaminant in ready-to-eat foods such as lunch meats and dairy products. Once ingested, these bacteria invade intestinal epithelial cells and translocate to the liver, where they grow inside hepatic cells. Listeriosis is fatal in about one in five normal healthy people, and mortality rates are slightly higher in patients with pre-existing conditions that weaken the immune response. A cluster of virulence genes encoded on a pathogenicity island is responsible for the pathogenicity of L. monocytogenes . These genes are regulated by a transcriptional factor known as peptide chain release factor 1 (PrfA). One of the genes regulated by PrfA is hyl , which encodes a toxin known as listeriolysin O (LLO), which allows the bacterium to escape vacuoles upon entry into a host cell. A second gene regulated by PrfA is actA, which encodes for a surface protein known as actin assembly-inducing protein (ActA). ActA is expressed on the surface of Listeria and polymerizes host actin. This enables the bacterium to produce actin tails , move around the cell’s cytoplasm, and spread from cell to cell without exiting into the extracellular compartment. Michael’s condition has begun to worsen. He is now experiencing a stiff neck and hemiparesis (weakness of one side of the body). Concerned that the infection is spreading, the physician decides to conduct additional tests to determine what is causing these new symptoms. What kind of pathogen causes listeriosis, and what virulence factors contribute to the signs and symptoms Michael is experiencing? Is it likely that the infection will spread from Michael’s blood? If so, how might this explain his new symptoms? Jump to the next Clinical Focus box. Go back to the previous Clinical Focus box. Bacterial Exoenzymes and Toxins as Virulence Factors After exposure and adhesion, the next step in pathogenesis is invasion , which can involve enzymes and toxins. Many pathogens achieve invasion by entering the bloodstream, an effective means of dissemination because blood vessels pass close to every cell in the body. The downside of this mechanism of dispersal is that the blood also includes numerous elements of the immune system. Various terms ending in –emia are used to describe the presence of pathogens in the bloodstream. The presence of bacteria in blood is called bacteremia . Bacteremia involving pyogens (pus-forming bacteria) is called pyemia . When viruses are found in the blood, it is called viremia . The term toxemia describes the condition when toxins are found in the blood. If bacteria are both present and multiplying in the blood, this condition is called septicemia . Patients with septicemia are described as septic , which can lead to shock , a life-threatening decrease in blood pressure (systolic pressure <90 mm Hg) that prevents cells and organs from receiving enough oxygen and nutrients. Some bacteria can cause shock through the release of toxins (virulence factors that can cause tissue damage) and lead to low blood pressure. Gram-negative bacteria are engulfed by immune system phagocytes, which then release tumor necrosis factor , a molecule involved in inflammation and fever. Tumor necrosis factor binds to blood capillaries to increase their permeability, allowing fluids to pass out of blood vessels and into tissues, causing swelling, or edema ( Figure 15.10 ). With high concentrations of tumor necrosis factor, the inflammatory reaction is severe and enough fluid is lost from the circulatory system that blood pressure decreases to dangerously low levels. This can have dire consequences because the heart, lungs, and kidneys rely on normal blood pressure for proper function; thus, multi-organ failure, shock, and death can occur. Exoenzymes Some pathogens produce extracellular enzymes, or exoenzyme s , that enable them to invade host cells and deeper tissues. Exoenzymes have a wide variety of targets. Some general classes of exoenzymes and associated pathogens are listed in Table 15.8 . Each of these exoenzymes functions in the context of a particular tissue structure to facilitate invasion or support its own growth and defend against the immune system. For example, hyaluronidase S, an enzyme produced by pathogens like Staphylococcus aureus , Streptococcus pyogenes , and Clostridium perfringens , degrades the glycoside hyaluronan (hyaluronic acid), which acts as an intercellular cement between adjacent cells in connective tissue ( Figure 15.11 ). This allows the pathogen to pass through the tissue layers at the portal of entry and disseminate elsewhere in the body ( Figure 15.11 ). Some Classes of Exoenzymes and Their Targets Class Example Function Glycohydrolases Hyaluronidase S in Staphylococcus aureus Degrades hyaluronic acid that cements cells together to promote spreading through tissues Nucleases DNAse produced by S. aureus Degrades DNA released by dying cells (bacteria and host cells) that can trap the bacteria, thus promoting spread Phospholipases Phospholipase C of Bacillus anthracis Degrades phospholipid bilayer of host cells, causing cellular lysis, and degrade membrane of phagosomes to enable escape into the cytoplasm Proteases Collagenase in Clostridium perfringens Degrades collagen in connective tissue to promote spread Table 15.8 Pathogen-produced nucleases, such as DNAse produced by S. aureus, degrade extracellular DNA as a means of escape and spreading through tissue. As bacterial and host cells die at the site of infection, they lyse and release their intracellular contents. The DNA chromosome is the largest of the intracellular molecules, and masses of extracellular DNA can trap bacteria and prevent their spread. S. aureus produces a DNAse to degrade the mesh of extracellular DNA so it can escape and spread to adjacent tissues. This strategy is also used by S. aureus and other pathogens to degrade and escape webs of extracellular DNA produced by immune system phagocytes to trap the bacteria. Enzymes that degrade the phospholipids of cell membranes are called phospholipases . Their actions are specific in regard to the type of phospholipids they act upon and where they enzymatically cleave the molecules. The pathogen responsible for anthrax , B. anthracis, produces phospholipase C. When B. anthracis is ingested by phagocytic cells of the immune system, phospholipase C degrades the membrane of the phagosome before it can fuse with the lysosome, allowing the pathogen to escape into the cytoplasm and multiply. Phospholipases can also target the membrane that encloses the phagosome within phagocytic cells. As described earlier in this chapter, this is the mechanism used by intracellular pathogens such as L. monocytogenes and Rickettsia to escape the phagosome and multiply within the cytoplasm of phagocytic cells. The role of phospholipases in bacterial virulence is not restricted to phagosomal escape. Many pathogens produce phospholipases that act to degrade cell membranes and cause lysis of target cells. These phospholipases are involved in lysis of red blood cells, white blood cells, and tissue cells. Bacterial pathogens also produce various protein-digesting enzymes, or proteases. Proteases can be classified according to their substrate target (e.g., serine proteases target proteins with the amino acid serine) or if they contain metals in their active site (e.g., zinc metalloproteases contain a zinc ion, which is necessary for enzymatic activity). One example of a protease that contains a metal ion is the exoenzyme collagenase . Collagenase digests collagen, the dominant protein in connective tissue. Collagen can be found in the extracellular matrix, especially near mucosal membranes, blood vessels, nerves, and in the layers of the skin. Similar to hyaluronidase, collagenase allows the pathogen to penetrate and spread through the host tissue by digesting this connective tissue protein. The collagenase produced by the gram-positive bacterium Clostridium perfringens , for example, allows the bacterium to make its way through the tissue layers and subsequently enter and multiply in the blood (septicemia). C. perfringens then uses toxins and a phospholipase to cause cellular lysis and necrosis. Once the host cells have died, the bacterium produces gas by fermenting the muscle carbohydrates. The widespread necrosis of tissue and accompanying gas are characteristic of the condition known as gas gangrene ( Figure 15.12 ). Link to Learning Two types of cell death are apoptosis and necrosis. Visit this website to learn more about the differences between these mechanisms of cell death and their causes. Toxins In addition to exoenzymes, certain pathogens are able to produce toxin s , biological poisons that assist in their ability to invade and cause damage to tissues. The ability of a pathogen to produce toxins to cause damage to host cells is called toxigenicity . Toxins can be categorized as endotoxins or exotoxins. The lipopolysaccharide (LPS) found on the outer membrane of gram-negative bacteria is called endotoxin ( Figure 15.13 ). During infection and disease, gram-negative bacterial pathogens release endotoxin either when the cell dies, resulting in the disintegration of the membrane, or when the bacterium undergoes binary fission. The lipid component of endotoxin, lipid A , is responsible for the toxic properties of the LPS molecule. Lipid A is relatively conserved across different genera of gram-negative bacteria; therefore, the toxic properties of lipid A are similar regardless of the gram-negative pathogen. In a manner similar to that of tumor necrosis factor, lipid A triggers the immune system’s inflammatory response (see Inflammation and Fever ). If the concentration of endotoxin in the body is low, the inflammatory response may provide the host an effective defense against infection; on the other hand, high concentrations of endotoxin in the blood can cause an excessive inflammatory response, leading to a severe drop in blood pressure, multi-organ failure, and death. A classic method of detecting endotoxin is by using the Limulus amebocyte lysate (LAL) test . In this procedure, the blood cells (amebocytes) of the horseshoe crab ( Limulus polyphemus ) is mixed with a patient’s serum. The amebocytes will react to the presence of any endotoxin. This reaction can be observed either chromogenically (color) or by looking for coagulation (clotting reaction) to occur within the serum. An alternative method that has been used is an enzyme-linked immunosorbent assay ( ELISA ) that uses antibodies to detect the presence of endotoxin. Unlike the toxic lipid A of endotoxin, exotoxin s are protein molecules that are produced by a wide variety of living pathogenic bacteria. Although some gram-negative pathogens produce exotoxins, the majority are produced by gram-positive pathogens. Exotoxins differ from endotoxin in several other key characteristics, summarized in Table 15.9 . In contrast to endotoxin, which stimulates a general systemic inflammatory response when released, exotoxins are much more specific in their action and the cells they interact with. Each exotoxin targets specific receptors on specific cells and damages those cells through unique molecular mechanisms. Endotoxin remains stable at high temperatures, and requires heating at 121 °C (250 °F) for 45 minutes to inactivate. By contrast, most exotoxins are heat labile because of their protein structure, and many are denatured (inactivated) at temperatures above 41 °C (106 °F). As discussed earlier, endotoxin can stimulate a lethal inflammatory response at very high concentrations and has a measured LD 50 of 0.24 mg/kg. By contrast, very small concentrations of exotoxins can be lethal. For example, botulinum toxin , which causes botulism , has an LD 50 of 0.000001 mg/kg (240,000 times more lethal than endotoxin). Comparison of Endotoxin and Exotoxins Produced by Bacteria Characteristic Endotoxin Exotoxin Source Gram-negative bacteria Gram-positive (primarily) and gram-negative bacteria Composition Lipid A component of lipopolysaccharide Protein Effect on host General systemic symptoms of inflammation and fever Specific damage to cells dependent upon receptor-mediated targeting of cells and specific mechanisms of action Heat stability Heat stable Most are heat labile, but some are heat stable LD 50 High Low Table 15.9 The exotoxins can be grouped into three categories based on their target: intracellular targeting, membrane disrupting, and superantigens. Table 15.10 provides examples of well-characterized toxins within each of these three categories. Some Common Exotoxins and Associated Bacterial Pathogens Category Example Pathogen Mechanism and Disease Intracellular-targeting toxins Cholera toxin Vibrio cholerae Activation of adenylate cyclase in intestinal cells, causing increased levels of cyclic adenosine monophosphate (cAMP) and secretion of fluids and electrolytes out of cell, causing diarrhea Tetanus toxin Clostridium tetani Inhibits the release of inhibitory neurotransmitters in the central nervous system, causing spastic paralysis Botulinum toxin Clostridium botulinum Inhibits release of the neurotransmitter acetylcholine from neurons, resulting in flaccid paralysis Diphtheria toxin Corynebacterium diphtheriae Inhibition of protein synthesis, causing cellular death Membrane-disrupting toxins Streptolysin Streptococcus pyogenes Proteins that assemble into pores in cell membranes, disrupting their function and killing the cell Pneumolysin Streptococcus pneumoniae Alpha-toxin Staphylococcus aureus Alpha-toxin Clostridium perfringens Phospholipases that degrade cell membrane phospholipids, disrupting membrane function and killing the cell Phospholipase C Pseudomonas aeruginosa Beta-toxin Staphylococcus aureus Superantigens Toxic shock syndrome toxin Staphylococcus aureus Stimulates excessive activation of immune system cells and release of cytokines (chemical mediators) from immune system cells. Life-threatening fever, inflammation, and shock are the result. Streptococcal mitogenic exotoxin Streptococcus pyogenes Streptococcal pyrogenic toxins Streptococcus pyogenes Table 15.10 The intracellular targeting toxin s comprise two components: A for activity and B for binding. Thus, these types of toxins are known as A-B exotoxins ( Figure 15.14 ). The B component is responsible for the cellular specificity of the toxin and mediates the initial attachment of the toxin to specific cell surface receptors. Once the A-B toxin binds to the host cell, it is brought into the cell by endocytosis and entrapped in a vacuole. The A and B subunits separate as the vacuole acidifies. The A subunit then enters the cell cytoplasm and interferes with the specific internal cellular function that it targets. Four unique examples of A-B toxins are the diphtheria, cholera, botulinum, and tetanus toxins. The diphtheria toxin is produced by the gram-positive bacterium Corynebacterium diphtheriae , the causative agent of nasopharyngeal and cutaneous diphtheria. After the A subunit of the diphtheria toxin separates and gains access to the cytoplasm, it facilitates the transfer of adenosine diphosphate (ADP)-ribose onto an elongation-factor protein (EF-2) that is needed for protein synthesis. Hence, diphtheria toxin inhibits protein synthesis in the host cell, ultimately killing the cell ( Figure 15.15 ). Cholera toxin is an enterotoxin produced by the gram-negative bacterium Vibrio cholerae and is composed of one A subunit and five B subunits. The mechanism of action of the cholera toxin is complex. The B subunits bind to receptors on the intestinal epithelial cell of the small intestine. After gaining entry into the cytoplasm of the epithelial cell, the A subunit activates an intracellular G protein. The activated G protein, in turn, leads to the activation of the enzyme adenyl cyclase, which begins to produce an increase in the concentration of cyclic AMP (a secondary messenger molecule). The increased cAMP disrupts the normal physiology of the intestinal epithelial cells and causes them to secrete excessive amounts of fluid and electrolytes into the lumen of the intestinal tract, resulting in severe “rice-water stool” diarrhea characteristic of cholera. Botulinum toxin (also known as botox ) is a neurotoxin produced by the gram-positive bacterium Clostridium botulinum . It is the most acutely toxic substance known to date. The toxin is composed of a light A subunit and heavy protein chain B subunit. The B subunit binds to neurons to allow botulinum toxin to enter the neurons at the neuromuscular junction. The A subunit acts as a protease, cleaving proteins involved in the neuron’s release of acetylcholine , a neurotransmitter molecule. Normally, neurons release acetylcholine to induce muscle fiber contractions. The toxin’s ability to block acetylcholine release results in the inhibition of muscle contractions, leading to muscle relaxation. This has the potential to stop breathing and cause death. Because of its action, low concentrations of botox are used for cosmetic and medical procedures, including the removal of wrinkles and treatment of overactive bladder. Link to Learning Click this link to see an animation of how the cholera toxin functions. Click this link to see an animation of how the botulinum toxin functions. Another neurotoxin is tetanus toxin , which is produced by the gram-positive bacterium Clostridium tetani . This toxin also has a light A subunit and heavy protein chain B subunit. Unlike botulinum toxin, tetanus toxin binds to inhibitory interneurons, which are responsible for release of the inhibitory neurotransmitters glycine and gamma-aminobutyric acid (GABA). Normally, these neurotransmitters bind to neurons at the neuromuscular junction, resulting in the inhibition of acetylcholine release. Tetanus toxin inhibits the release of glycine and GABA from the interneuron, resulting in permanent muscle contraction. The first symptom is typically stiffness of the jaw (lockjaw). Violent muscle spasms in other parts of the body follow, typically culminating with respiratory failure and death. Figure 15.16 shows the actions of both botulinum and tetanus toxins. Membrane-disrupting toxins affect cell membrane function either by forming pores or by disrupting the phospholipid bilayer in host cell membranes. Two types of membrane-disrupting exotoxins are hemolysin s and leukocidins , which form pores in cell membranes, causing leakage of the cytoplasmic contents and cell lysis. These toxins were originally thought to target red blood cells (erythrocytes) and white blood cells (leukocytes), respectively, but we now know they can affect other cells as well. The gram-positive bacterium Streptococcus pyogenes produces streptolysins , water-soluble hemolysins that bind to the cholesterol moieties in the host cell membrane to form a pore. The two types of streptolysins, O and S, are categorized by their ability to cause hemolysis in erythrocytes in the absence or presence of oxygen. Streptolysin O is not active in the presence of oxygen, whereas streptolysin S is active in the presence of oxygen. Other important pore-forming membrane-disrupting toxins include alpha toxin of Staphylococcus aureus and pneumolysin of Streptococcus pneumoniae . Bacterial phospholipases are membrane-disrupting toxin s that degrade the phospholipid bilayer of cell membranes rather than forming pores. We have already discussed the phospholipases associated with B. anthracis, L. pneumophila, and Rickettsia species that enable these bacteria to effect the lysis of phagosomes. These same phospholipases are also hemolysins. Other phospholipases that function as hemolysins include the alpha toxin of Clostridium perfringens , phospholipase C of P. aeruginosa , and beta toxin of Staphylococcus aureus . Some strains of S. aureus also produce a leukocidin called Panton-Valentine leukocidin (PVL) . PVL consists of two subunits, S and F. The S component acts like the B subunit of an A-B exotoxin in that it binds to glycolipids on the outer plasma membrane of animal cells. The F-component acts like the A subunit of an A-B exotoxin and carries the enzymatic activity. The toxin inserts and assembles into a pore in the membrane. Genes that encode PVL are more frequently present in S. aureus strains that cause skin infections and pneumonia. 8 PVL promotes skin infections by causing edema, erythema (reddening of the skin due to blood vessel dilation), and skin necrosis. PVL has also been shown to cause necrotizing pneumonia. PVL promotes pro-inflammatory and cytotoxic effects on alveolar leukocytes. This results in the release of enzymes from the leukocytes, which, in turn, cause damage to lung tissue. 8 V. Meka. “Panton-Valentine Leukocidin.” http://www.antimicrobe.org/h04c.files/history/PVL-S-aureus.asp The third class of exotoxins is the superantigen s . These are exotoxins that trigger an excessive, nonspecific stimulation of immune cells to secrete cytokines (chemical messengers). The excessive production of cytokines, often called a cytokine storm , elicits a strong immune and inflammatory response that can cause life-threatening high fevers, low blood pressure, multi-organ failure, shock, and death. The prototype superantigen is the toxic shock syndrome toxin of S. aureus . Most toxic shock syndrome cases are associated with vaginal colonization by toxin-producing S. aureus in menstruating women; however, colonization of other body sites can also occur. Some strains of Streptococcus pyogenes also produce superantigens; they are referred to as the streptococcal mitogenic exotoxins and the streptococcal pyrogenic toxins . Check Your Understanding Describe how exoenzymes contribute to bacterial invasion. Explain the difference between exotoxins and endotoxin. Name the three classes of exotoxins. Virulence Factors for Survival in the Host and Immune Evasion Evading the immune system is also important to invasiveness. Bacteria use a variety of virulence factors to evade phagocytosis by cells of the immune system. For example, many bacteria produce capsules , which are used in adhesion but also aid in immune evasion by preventing ingestion by phagocytes. The composition of the capsule prevents immune cells from being able to adhere and then phagocytose the cell. In addition, the capsule makes the bacterial cell much larger, making it harder for immune cells to engulf the pathogen ( Figure 15.17 ). A notable capsule-producing bacterium is the gram-positive pathogen Streptococcus pneumoniae , which causes pneumococcal pneumonia, meningitis, septicemia, and other respiratory tract infections. Encapsulated strains of S. pneumoniae are more virulent than nonencapsulated strains and are more likely to invade the bloodstream and cause septicemia and meningitis. Some pathogens can also produce proteases to protect themselves against phagocytosis. As described in Adaptive Specific Host Defenses , the human immune system produces antibodies that bind to surface molecules found on specific bacteria (e.g., capsules , fimbriae , flagella , LPS ). This binding initiates phagocytosis and other mechanisms of antibacterial killing and clearance. Proteases combat antibody-mediated killing and clearance by attacking and digesting the antibody molecules ( Figure 15.17 ). In addition to capsules and proteases, some bacterial pathogens produce other virulence factors that allow them to evade the immune system. The fimbriae of certain species of Streptococcus contain M protein , which alters the surface of Streptococcus and inhibits phagocytosis by blocking the binding of the complement molecules that assist phagocytes in ingesting bacterial pathogens. The acid-fast bacterium Mycobacterium tuberculosis (the causative agent of tuberculosis ) produces a waxy substance known as mycolic acid in its cell envelope. When it is engulfed by phagocytes in the lung, the protective mycolic acid coat enables the bacterium to resist some of the killing mechanisms within the phagolysosome. Some bacteria produce virulence factors that promote infection by exploiting molecules naturally produced by the host. For example, most strains of Staphylococcus aureus produce the exoenzyme coagulase , which exploits the natural mechanism of blood clotting to evade the immune system. Normally, blood clotting is triggered in response to blood vessel damage; platelets begin to plug the clot, and a cascade of reactions occurs in which fibrinogen, a soluble protein made by the liver, is cleaved into fibrin . Fibrin is an insoluble, thread-like protein that binds to blood platelets, cross-links, and contracts to form a mesh of clumped platelets and red blood cells. The resulting clot prevents further loss of blood from the damaged blood vessels. However, if bacteria release coagulase into the bloodstream, the fibrinogen-to-fibrin cascade is triggered in the absence of blood vessel damage. The resulting clot coats the bacteria in fibrin, protecting the bacteria from exposure to phagocytic immune cells circulating in the bloodstream. Whereas coagulase causes blood to clot, kinases have the opposite effect by triggering the conversion of plasminogen to plasmin, which is involved in the digestion of fibrin clots. By digesting a clot, kinases allow pathogens trapped in the clot to escape and spread, similar to the way that collagenase, hyaluronidase, and DNAse facilitate the spread of infection. Examples of kinases include staphylokinases and streptokinases , produced by Staphylococcus aureus and Streptococcus pyogenes , respectively. It is intriguing that S. aureus can produce both coagulase to promote clotting and staphylokinase to stimulate the digestion of clots. The action of the coagulase provides an important protective barrier from the immune system, but when nutrient supplies are diminished or other conditions signal a need for the pathogen to escape and spread, the production of staphylokinase can initiate this process. A final mechanism that pathogens can use to protect themselves against the immune system is called antigenic variation , which is the alteration of surface proteins so that a pathogen is no longer recognized by the host’s immune system. For example, the bacterium Borrelia burgdorferi , the causative agent of Lyme disease , contains a surface lipoprotein known as VlsE . Because of genetic recombination during DNA replication and repair, this bacterial protein undergoes antigenic variation. Each time fever occurs, the VlsE protein in B. burgdorferi can differ so much that antibodies against previous VlsE sequences are not effective. It is believed that this variation in the VlsE contributes to the ability B. burgdorferi to cause chronic disease. Another important human bacterial pathogen that uses antigenic variation to avoid the immune system is Neisseria gonorrhoeae , which causes the sexually transmitted disease gonorrhea . This bacterium is well known for its ability to undergo antigenic variation of its type IV pili to avoid immune defenses. Check Your Understanding Name at least two ways that a capsule provides protection from the immune system. Besides capsules, name two other virulence factors used by bacteria to evade the immune system. Clinical Focus Resolution Based on Michael’s reported symptoms of stiff neck and hemiparesis, the physician suspects that the infection may have spread to his nervous system. The physician decides to order a spinal tap to look for any bacteria that may have invaded the meninges and cerebrospinal fluid (CSF), which would normally be sterile. To perform the spinal tap, Michael’s lower back is swabbed with an iodine antiseptic and then covered with a sterile sheet. The needle is aseptically removed from the manufacturer’s sealed plastic packaging by the clinician’s gloved hands. The needle is inserted and a small volume of fluid is drawn into an attached sample tube. The tube is removed, capped and a prepared label with Michael’s data is affixed to it. This STAT (urgent or immediate analysis required) specimen is divided into three separate sterile tubes, each with 1 mL of CSF. These tubes are immediately taken to the hospital’s lab, where they are analyzed in the clinical chemistry, hematology, and microbiology departments. The preliminary results from all three departments indicate there is a cerebrospinal infection occurring, with the microbiology department reporting the presence of a gram-positive rod in Michael’s CSF. These results confirm what his physician had suspected: Michael’s new symptoms are the result of meningitis , acute inflammation of the membranes that protect the brain and spinal cord. Because meningitis can be life threatening and because the first antibiotic therapy was not effective in preventing the spread of infection, Michael is prescribed an aggressive course of two antibiotics, ampicillin and gentamicin, to be delivered intravenously. Michael remains in the hospital for several days for supportive care and for observation. After a week, he is allowed to return home for bed rest and oral antibiotics. After 3 weeks of this treatment, he makes a full recovery. Go back to the previous Clinical Focus box. Viral Virulence Although viral pathogens are not similar to bacterial pathogens in terms of structure, some of the properties that contribute to their virulence are similar. Viruses use adhesins to facilitate adhesion to host cells, and certain enveloped viruses rely on antigenic variation to avoid the host immune defenses. These virulence factors are discussed in more detail in the following sections. Viral Adhesins One of the first steps in any viral infection is adhesion of the virus to specific receptors on the surface of cells. This process is mediated by adhesins that are part of the viral capsid or membrane envelope . The interaction of viral adhesins with specific cell receptors defines the tropism (preferential targeting) of viruses for specific cells, tissues, and organs in the body. The spike protein hemagglutinin found on Influenzavirus is an example of a viral adhesin; it allows the virus to bind to the sialic acid on the membrane of host respiratory and intestinal cells. Another viral adhesin is the glycoprotein gp20, found on HIV . For HIV to infect cells of the immune system, it must interact with two receptors on the surface of cells. The first interaction involves binding between gp120 and the CD4 cellular marker that is found on some essential immune system cells. However, before viral entry into the cell can occur, a second interaction between gp120 and one of two chemokine receptors (CCR5 and CXCR4) must occur. Table 15.11 lists the adhesins for some common viral pathogens and the specific sites to which these adhesins allow viruses to attach. Some Viral Adhesins and Their Host Attachment Sites Pathogen Disease Adhesin Attachment Site Influenzavirus Influenza Hemagglutinin Sialic acid of respiratory and intestinal cells Herpes simplex virus I or II Oral herpes, genital herpes Glycoproteins gB, gC, gD Heparan sulfate on mucosal surfaces of the mouth and genitals Human immunodeficiency virus HIV/AIDS Glycoprotein gp120 CD4 and CCR5 or CXCR4 of immune system cells Table 15.11 Antigenic Variation in Viruses Antigenic variation also occurs in certain types of enveloped viruses, including influenza viruses, which exhibit two forms of antigenic variation: antigenic drift and antigenic shift ( Figure 15.18 ). Antigenic drift is the result of point mutations causing slight changes in the spike proteins hemagglutinin (H) and neuraminidase (N). On the other hand, antigenic shift is a major change in spike proteins due to gene reassortment. This reassortment for antigenic shift occurs typically when two different influenza viruses infect the same host. The rate of antigenic variation in influenza viruses is very high, making it difficult for the immune system to recognize the many different strains of Influenzavirus. Although the body may develop immunity to one strain through natural exposure or vaccination, antigenic variation results in the continual emergence of new strains that the immune system will not recognize. This is the main reason that vaccines against Influenzavirus must be given annually. Each year’s influenza vaccine provides protection against the most prevalent strains for that year, but new or different strains may be more prevalent the following year. Link to Learning For another explanation of how antigenic shift and drift occur, watch this video. Check Your Understanding Describe the role of adhesins in viral tropism. Explain the difference between antigenic drift and antigenic shift. 15.4 Virulence Factors of Eukaryotic Pathogens Learning Objectives Describe virulence factors unique to fungi and parasites Compare virulence factors of fungi and bacteria Explain the difference between protozoan parasites and helminths Describe how helminths evade the host immune system Although fungi and parasites are important pathogens causing infectious diseases, their pathogenic mechanisms and virulence factors are not as well characterized as those of bacteria. Despite the relative lack of detailed mechanisms, the stages of pathogenesis and general mechanisms of virulence involved in disease production by these pathogens are similar to those of bacteria. Fungal Virulence Pathogenic fungi can produce virulence factors that are similar to the bacterial virulence factors that have been discussed earlier in this chapter. In this section, we will look at the virulence factors associated with species of Candida , Cryptococcus, Claviceps, and Aspergillus . Candida albicans is an opportunistic fungal pathogen and causative agent of oral thrush, vaginal yeast infections, and cutaneous candidiasis. Candida produces adhesins (surface glycoproteins) that bind to the phospholipids of epithelial and endothelial cells. To assist in spread and tissue invasion, Candida produces proteases and phospholipases (i.e., exoenzymes). One of these proteases degrades keratin, a structural protein found on epithelial cells, enhancing the ability of the fungus to invade host tissue. In animal studies, it has been shown that the addition of a protease inhibitor led to attenuation of Candida infection. 9 Similarly, the phospholipases can affect the integrity of host cell membranes to facilitate invasion. 9 K. Fallon et al. “Role of Aspartic Proteases in Disseminated Candida albicans Infection in Mice.” Infection and Immunity 65 no. 2 (1997):551–556. The main virulence factor for Cryptococcus , a fungus that causes pneumonia and meningitis, is capsule production. The polysaccharide glucuronoxylomannan is the principal constituent of the Cryptococcus capsule. Similar to encapsulated bacterial cells, encapsulated Cryptococcus cells are more resistant to phagocytosis than nonencapsulated Cryptococcus , which are effectively phagocytosed and, therefore, less virulent. Like some bacteria, many fungi produce exotoxins. Fungal toxins are called mycotoxin s . Claviceps purpurea , a fungus that grows on rye and related grains, produces a mycotoxin called ergot toxin, an alkaloid responsible for the disease known as ergotism . There are two forms of ergotism: gangrenous and convulsive. In gangrenous ergotism , the ergot toxin causes vasoconstriction, resulting in improper blood flow to the extremities, eventually leading to gangrene. A famous outbreak of gangrenous ergotism occurred in Eastern Europe during the 5th century AD due to the consumption of rye contaminated with C. purpurea . In convulsive ergotism , the toxin targets the central nervous system, causing mania and hallucinations. The mycotoxin aflatoxin is a virulence factor produced by the fungus Aspergillus , an opportunistic pathogen that can enter the body via contaminated food or by inhalation. Inhalation of the fungus can lead to the chronic pulmonary disease aspergillosis , characterized by fever, bloody sputum, and/or asthma. Aflatoxin acts in the host as both a mutagen (a substance that causes mutations in DNA) and a carcinogen (a substance involved in causing cancer), and has been associated with the development of liver cancer . Aflatoxin has also been shown to cross the blood-placental barrier. 10 A second mycotoxin produced by Aspergillus is gliotoxin . This toxin promotes virulence by inducing host cells to self-destruct and by evading the host’s immune response by inhibiting the function of phagocytic cells as well as the pro-inflammatory response. Like Candida , Aspergillus also produces several proteases. One is elastase , which breaks down the protein elastin found in the connective tissue of the lung, leading to the development of lung disease. Another is catalase , an enzyme that protects the fungus from hydrogen peroxide produced by the immune system to destroy pathogens. 10 C.P. Wild et al. “In-utero exposure to aflatoxin in west Africa.” Lancet 337 no. 8757 (1991):1602. Check Your Understanding List virulence factors common to bacteria and fungi. What functions do mycotoxins perform to help fungi survive in the host? Protozoan Virulence Protozoan pathogens are unicellular eukaryotic parasites that have virulence factors and pathogenic mechanisms analogous to prokaryotic and viral pathogens, including adhesins, toxins, antigenic variation, and the ability to survive inside phagocytic vesicles. Protozoans often have unique features for attaching to host cells. The protozoan Giardia lamblia , which causes the intestinal disease giardiasis, uses a large adhesive disc composed of microtubules to attach to the intestinal mucosa. During adhesion, the flagella of G. lamblia move in a manner that draws fluid out from under the disc, resulting in an area of lower pressure that facilitates adhesion to epithelial cells. Giardia does not invade the intestinal cells but rather causes inflammation (possibly through the release of cytopathic substances that cause damage to the cells) and shortens the intestinal villi, inhibiting absorption of nutrients. Some protozoans are capable of antigenic variation . The obligate intracellular pathogen Plasmodium falciparum (one of the causative agents of malaria ) resides inside red blood cells, where it produces an adhesin membrane protein known as PfEMP1. This protein is expressed on the surface of the infected erythrocytes, causing blood cells to stick to each other and to the walls of blood vessels. This process impedes blood flow, sometimes leading to organ failure, anemia, jaundice (yellowing of skin and sclera of the eyes due to buildup of bilirubin from lysed red blood cells), and, subsequently, death. Although PfEMP1 can be recognized by the host’s immune system, antigenic variations in the structure of the protein over time prevent it from being easily recognized and eliminated. This allows malaria to persist as a chronic infection in many individuals. The virulence factors of Trypanosoma brucei , the causative agent of African sleeping sickness , include the abilities to form capsules and undergo antigenic variation . T. brucei evades phagocytosis by producing a dense glycoprotein coat that resembles a bacterial capsule. Over time, host antibodies are produced that recognize this coat, but T. brucei is able to alter the structure of the glycoprotein to evade recognition. Check Your Understanding Explain how antigenic variation by protozoan pathogens helps them survive in the host. Helminth Virulence Helminths, or parasitic worms, are multicellular eukaryotic parasites that depend heavily on virulence factors that allow them to gain entry to host tissues. For example, the aquatic larval form of Schistosoma mansoni , which causes schistosomiasis , penetrates intact skin with the aid of proteases that degrade skin proteins, including elastin. To survive within the host long enough to perpetuate their often-complex life cycles, helminths need to evade the immune system. Some helminths are so large that the immune system is ineffective against them. Others, such as adult roundworms (which cause trichinosis , ascariasis , and other diseases), are protected by a tough outer cuticle. Over the course of their life cycles, the surface characteristics of the parasites vary, which may help prevent an effective immune response. Some helminths express polysaccharides called glycans on their external surface; because these glycans resemble molecules produced by host cells, the immune system fails to recognize and attack the helminth as a foreign body. This “ glycan gimmickry ,” as it has been called, serves as a protective cloak that allows the helminth to escape detection by the immune system. 11 11 I. van Die, R.D. Cummings. “Glycan Gimmickry by Parasitic Helminths: A Strategy for Modulating the Host Immune Response?” Glycobiology 20 no. 1 (2010):2–12. In addition to evading host defenses, helminths can actively suppress the immune system. S. mansoni , for example, degrades host antibodies with proteases . Helminths produce many other substances that suppress elements of both innate nonspecific and adaptive specific host defenses. They also release large amounts of material into the host that may locally overwhelm the immune system or cause it to respond inappropriately. Check Your Understanding Describe how helminths avoid being destroyed by the host immune system.
microbiology
Summary 11.1 The Functions of Genetic Material DNA serves two important cellular functions: It is the genetic material passed from parent to offspring and it serves as the information to direct and regulate the construction of the proteins necessary for the cell to perform all of its functions. The central dogma states that DNA organized into genes specifies the sequences of messenger RNA (mRNA), which, in turn, specifies the amino acid sequence of proteins. The genotype of a cell is the full collection of genes a cell contains. Not all genes are used to make proteins simultaneously. The phenotype is a cell’s observable characteristics resulting from the proteins it is producing at a given time under specific environmental conditions. 11.2 DNA Replication The DNA replication process is semiconservative , which results in two DNA molecules, each having one parental strand of DNA and one newly synthesized strand. In bacteria, the initiation of replication occurs at the origin of replication , where supercoiled DNA is unwound by DNA gyrase , made single-stranded by helicase , and bound by single-stranded binding protein to maintain its single-stranded state. Primase synthesizes a short RNA primer , providing a free 3’-OH group to which DNA polymerase III can add DNA nucleotides. During elongation , the leading strand of DNA is synthesized continuously from a single primer. The lagging strand is synthesized discontinuously in short Okazaki fragments , each requiring its own primer. The RNA primers are removed and replaced with DNA nucleotides by bacterial DNA polymerase I , and DNA ligase seals the gaps between these fragments. Termination of replication in bacteria involves the resolution of circular DNA concatemers by topoisomerase IV to release the two copies of the circular chromosome. Eukaryotes typically have multiple linear chromosomes, each with multiple origins of replication. Overall, replication in eukaryotes is similar to that in prokaryotes. The linear nature of eukaryotic chromosomes necessitates telomeres to protect genes near the end of the chromosomes. Telomerase extends telomeres, preventing their degradation, in some cell types. Rolling circle replication is a type of rapid unidirectional DNA synthesis of a circular DNA molecule used for the replication of some plasmids. 11.3 RNA Transcription During transcription , the information encoded in DNA is used to make RNA. RNA polymerase synthesizes RNA, using the antisense strand of the DNA as template by adding complementary RNA nucleotides to the 3’ end of the growing strand. RNA polymerase binds to DNA at a sequence called a promoter during the initiation of transcription . Genes encoding proteins of related functions are frequently transcribed under the control of a single promoter in prokaryotes, resulting in the formation of a polycistronic mRNA molecule that encodes multiple polypeptides. Unlike DNA polymerase, RNA polymerase does not require a 3’-OH group to add nucleotides, so a primer is not needed during initiation. Termination of transcription in bacteria occurs when the RNA polymerase encounters specific DNA sequences that lead to stalling of the polymerase. This results in release of RNA polymerase from the DNA template strand, freeing the RNA transcript . Eukaryotes have three different RNA polymerases. Eukaryotes also have monocistronic mRNA, each encoding only a single polypeptide. Eukaryotic primary transcripts are processed in several ways, including the addition of a 5’ cap and a 3′- poly-A tail , as well as splicing , to generate a mature mRNA molecule that can be transported out of the nucleus and that is protected from degradation. 11.4 Protein Synthesis (Translation) In translation , polypeptides are synthesized using mRNA sequences and cellular machinery, including tRNAs that match mRNA codons to specific amino acids and ribosomes composed of RNA and proteins that catalyze the reaction. The genetic code is degenerate in that several mRNA codons code for the same amino acids. The genetic code is almost universal among living organisms. Prokaryotic (70S) and cytoplasmic eukaryotic (80S) ribosomes are each composed of a large subunit and a small subunit of differing sizes between the two groups. Each subunit is composed of rRNA and protein. Organelle ribosomes in eukaryotic cells resemble prokaryotic ribosomes. Some 60 to 90 species of tRNA exist in bacteria. Each tRNA has a three-nucleotide anticodon as well as a binding site for a cognate amino acid . All tRNAs with a specific anticodon will carry the same amino acid. Initiation of translation occurs when the small ribosomal subunit binds with initiation factors and an initiator tRNA at the start codon of an mRNA, followed by the binding to the initiation complex of the large ribosomal subunit. In prokaryotic cells, the start codon codes for N-formyl-methionine carried by a special initiator tRNA. In eukaryotic cells, the start codon codes for methionine carried by a special initiator tRNA. In addition, whereas ribosomal binding of the mRNA in prokaryotes is facilitated by the Shine-Dalgarno sequence within the mRNA, eukaryotic ribosomes bind to the 5’ cap of the mRNA. During the elongation stage of translation, a charged tRNA binds to mRNA in the A site of the ribosome; a peptide bond is catalyzed between the two adjacent amino acids, breaking the bond between the first amino acid and its tRNA; the ribosome moves one codon along the mRNA; and the first tRNA is moved from the P site of the ribosome to the E site and leaves the ribosomal complex. Termination of translation occurs when the ribosome encounters a stop codon , which does not code for a tRNA. Release factors cause the polypeptide to be released, and the ribosomal complex dissociates. In prokaryotes, transcription and translation may be coupled, with translation of an mRNA molecule beginning as soon as transcription allows enough mRNA exposure for the binding of a ribosome, prior to transcription termination. Transcription and translation are not coupled in eukaryotes because transcription occurs in the nucleus, whereas translation occurs in the cytoplasm or in association with the rough endoplasmic reticulum. Polypeptides often require one or more post-translational modifications to become biologically active. 11.5 Mutations A mutation is a heritable change in DNA. A mutation may lead to a change in the amino-acid sequence of a protein, possibly affecting its function. A point mutation affects a single base pair. A point mutation may cause a silent mutation if the mRNA codon codes for the same amino acid, a missense mutation if the mRNA codon codes for a different amino acid, or a nonsense mutation if the mRNA codon becomes a stop codon. Missense mutations may retain function, depending on the chemistry of the new amino acid and its location in the protein. Nonsense mutations produce truncated and frequently nonfunctional proteins. A frameshift mutation results from an insertion or deletion of a number of nucleotides that is not a multiple of three. The change in reading frame alters every amino acid after the point of the mutation and results in a nonfunctional protein. Spontaneous mutations occur through DNA replication errors, whereas induced mutations occur through exposure to a mutagen . Mutagenic agents are frequently carcinogenic but not always. However, nearly all carcinogens are mutagenic. Chemical mutagens include base analogs and chemicals that modify existing bases. In both cases, mutations are introduced after several rounds of DNA replication. Ionizing radiation, such as X-rays and γ-rays, leads to breakage of the phosphodiester backbone of DNA and can also chemically modify bases to alter their base-pairing rules. Nonionizing radiation like ultraviolet light may introduce pyrimidine (thymine) dimers, which, during DNA replication and transcription, may introduce frameshift or point mutations. Cells have mechanisms to repair naturally occurring mutations. DNA polymerase has proofreading activity. Mismatch repair is a process to repair incorrectly incorporated bases after DNA replication has been completed. Pyrimidine dimers can also be repaired. In nucleotide excision repair (dark repair) , enzymes recognize the distortion introduced by the pyrimidine dimer and replace the damaged strand with the correct bases, using the undamaged DNA strand as a template. Bacteria and other organisms may also use direct repair , in which the photolyase enzyme, in the presence of visible light, breaks apart the pyrimidines. Through comparison of growth on the complete plate and lack of growth on media lacking specific nutrients, specific loss-of-function mutants called auxotrophs can be identified. The Ames test is an inexpensive method that uses auxotrophic bacteria to measure mutagenicity of a chemical compound. Mutagenicity is an indicator of carcinogenic potential. 11.6 How Asexual Prokaryotes Achieve Genetic Diversity Horizontal gene transfer is an important way for asexually reproducing organisms like prokaryotes to acquire new traits. There are three mechanisms of horizontal gene transfer typically used by bacteria: transformation , transduction , and conjugation . Transformation allows for competent cells to take up naked DNA, released from other cells on their death, into their cytoplasm, where it may recombine with the host genome. In generalized transduction , any piece of chromosomal DNA may be transferred by accidental packaging of the degraded host chromosome into a phage head. In specialized transduction , only chromosomal DNA adjacent to the integration site of a lysogenic phage may be transferred as a result of imprecise excision of the prophage. Conjugation is mediated by the F plasmid, which encodes a conjugation pilus that brings an F plasmid-containing F + cell into contact with an F - cell . The rare integration of the F plasmid into the bacterial chromosome, generating an Hfr cell , allows for transfer of chromosomal DNA from the donor to the recipient. Additionally, imprecise excision of the F plasmid from the chromosome may generate an F’ plasmid that may be transferred to a recipient by conjugation. Conjugation transfer of R plasmids is an important mechanism for the spread of antibiotic resistance in bacterial communities. Transposons are molecules of DNA with inverted repeats at their ends that also encode the enzyme transposase, allowing for their movement from one location in DNA to another. Although found in both prokaryotes and eukaryotes, transposons are clinically relevant in bacterial pathogens for the movement of virulence factors, including antibiotic resistance genes. 11.7 Gene Regulation: Operon Theory Gene expression is a tightly regulated process. Gene expression in prokaryotes is largely regulated at the point of transcription. Gene expression in eukaryotes is additionally regulated post-transcriptionally. Prokaryotic structural genes of related function are often organized into operons , all controlled by transcription from a single promoter. The regulatory region of an operon includes the promoter itself and the region surrounding the promoter to which transcription factors can bind to influence transcription. Although some operons are constitutively expressed , most are subject to regulation through the use of transcription factors (repressors and activators). A repressor binds to an operator , a DNA sequence within the regulatory region between the RNA polymerase binding site in the promoter and first structural gene, thereby physically blocking transcription of these operons. An activator binds within the regulatory region of an operon, helping RNA polymerase bind to the promoter, thereby enhancing the transcription of this operon. An inducer influences transcription through interacting with a repressor or activator. The trp operon is a classic example of a repressible operon . When tryptophan accumulates, tryptophan binds to a repressor, which then binds to the operator, preventing further transcription. The lac operon is a classic example an inducible operon . When lactose is present in the cell, it is converted to allolactose. Allolactose acts as an inducer, binding to the repressor and preventing the repressor from binding to the operator. This allows transcription of the structural genes. The lac operon is also subject to activation. When glucose levels are depleted, some cellular ATP is converted into cAMP, which binds to the catabolite activator protein (CAP) . The cAMP-CAP complex activates transcription of the lac operon. When glucose levels are high, its presence prevents transcription of the lac operon and other operons by catabolite repression . Small intracellular molecules called alarmones are made in response to various environmental stresses, allowing bacteria to control the transcription of a group of operons, called a regulon. Bacteria have the ability to change which σ factor of RNA polymerase they use in response to environmental conditions to quickly and globally change which regulons are transcribed. Prokaryotes have regulatory mechanisms, including attenuation and the use of riboswitches , to simultaneously control the completion of transcription and translation from that transcript. These mechanisms work through the formation of stem loops in the 5’ end of an mRNA molecule currently being synthesized. There are additional points of regulation of gene expression in prokaryotes and eukaryotes. In eukaryotes, epigenetic regulation by chemical modification of DNA or histones, and regulation of RNA processing are two methods.
Chapter Outline 11.1 The Functions of Genetic Material 11.2 DNA Replication 11.3 RNA Transcription 11.4 Protein Synthesis (Translation) 11.5 Mutations 11.6 How Asexual Prokaryotes Achieve Genetic Diversity 11.7 Gene Regulation: Operon Theory Introduction In 1954, French scientist and future Nobel laureate Jacques Monod (1910–1976) famously said, “What is true in E. coli is true in the elephant,” suggesting that the biochemistry of life was maintained throughout evolution and is shared in all forms of known life. Since Monod’s famous statement, we have learned a great deal about the mechanisms of gene regulation, expression, and replication in living cells. All cells use DNA for information storage, share the same genetic code, and use similar mechanisms to replicate and express it. Although many aspects of genetics are universally shared, variations do exist among contemporary genetic systems. We now know that within the shared overall theme of the genetic mechanism, there are significant differences among the three domains of life: Eukarya, Archaea, and Bacteria. Additionally, viruses, cellular parasites but not themselves living cells, show dramatic variation in their genetic material and the replication and gene expression processes. Some of these differences have allowed us to engineer clinical tools such as antibiotics and antiviral drugs that specifically inhibit the reproduction of pathogens yet are harmless to their hosts.
[ { "answer": { "ans_choice": 3, "ans_text": "D" }, "bloom": null, "hl_context": "<hl> In addition to the mRNA template , many molecules and macromolecules contribute to the process of translation . <hl> <hl> The composition of each component varies across taxa ; for instance , ribosomes may consist of different numbers of ribosomal RNAs ( rRNAs ) and polypeptides depending on the organism . <hl> However , the general structures and functions of the protein synthesis machinery are comparable from bacteria to human cells . <hl> Translation requires the input of an mRNA template , ribosomes , tRNAs , and various enzymatic factors . <hl>", "hl_sentences": "In addition to the mRNA template , many molecules and macromolecules contribute to the process of translation . The composition of each component varies across taxa ; for instance , ribosomes may consist of different numbers of ribosomal RNAs ( rRNAs ) and polypeptides depending on the organism . Translation requires the input of an mRNA template , ribosomes , tRNAs , and various enzymatic factors .", "question": { "cloze_format": "DNA does all but ___ .", "normal_format": "DNA does all but which of the following?", "question_choices": [ "serves as the genetic material passed from parent to offspring", "remains constant despite changes in environmental conditions", "provides the instructions for the synthesis of messenger RNA", "is read by ribosomes during the process of translation" ], "question_id": "fs-id1167662911256", "question_text": "DNA does all but which of the following?" }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 1, "ans_text": "B" }, "bloom": null, "hl_context": "A gene is composed of DNA that is “ read ” or transcribed to produce an RNA molecule during the process of transcription . One major type of RNA molecule , called messenger RNA ( mRNA ) , provides the information for the ribosome to catalyze protein synthesis in a process called translation . The processes of transcription and translation are collectively referred to as gene expression . Gene expression is the synthesis of a specific protein with a sequence of amino acids that is encoded in the gene . <hl> The flow of genetic information from DNA to RNA to protein is described by the central dogma ( Figure 11.2 ) . <hl> This central dogma of molecular biology further elucidates the mechanism behind Beadle and Tatum ’ s “ one gene-one enzyme ” hypothesis ( see Using Microorganisms to Discover the Secrets of Life ) . Each of the processes of replication , transcription , and translation includes the stages of 1 ) initiation , 2 ) elongation ( polymerization ) , and 3 ) termination . These stages will be described in more detail in this chapter .", "hl_sentences": "The flow of genetic information from DNA to RNA to protein is described by the central dogma ( Figure 11.2 ) .", "question": { "cloze_format": "According to the central dogma, ___ represents the flow of genetic information in cells.", "normal_format": "According to the central dogma, which of the following represents the flow of genetic information in cells?", "question_choices": [ "protein to DNA to RNA", "DNA to RNA to protein", "RNA to DNA to protein", "DNA to protein to RNA" ], "question_id": "fs-id1167662675026", "question_text": "According to the central dogma, which of the following represents the flow of genetic information in cells?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 1, "ans_text": "B" }, "bloom": null, "hl_context": "The leading strand can be extended from one primer alone , whereas the lagging strand needs a new primer for each of the short Okazaki fragments . The overall direction of the lagging strand will be 3 ’ to 5 ’ , and that of the leading strand 5 ’ to 3 ’ . A protein called the sliding clamp holds the DNA polymerase in place as it continues to add nucleotides . The sliding clamp is a ring-shaped protein that binds to the DNA and holds the polymerase in place . Beyond its role in initiation , topoisomerase also prevents the overwinding of the DNA double helix ahead of the replication fork as the DNA is opening up ; it does so by causing temporary nicks in the DNA helix and then resealing it . <hl> As synthesis proceeds , the RNA primers are replaced by DNA . <hl> <hl> The primers are removed by the exonuclease activity of DNA polymerase I , and the gaps are filled in . <hl> The nicks that remain between the newly synthesized DNA ( that replaced the RNA primer ) and the previously synthesized DNA are sealed by the enzyme DNA ligase that catalyzes the formation of covalent phosphodiester linkage between the 3 ’ - OH end of one DNA fragment and the 5 ’ phosphate end of the other fragment , stabilizing the sugar-phosphate backbone of the DNA molecule .", "hl_sentences": "As synthesis proceeds , the RNA primers are replaced by DNA . The primers are removed by the exonuclease activity of DNA polymerase I , and the gaps are filled in .", "question": { "cloze_format": "___ is the enzyme that replaces the RNA nucleotides in a primer with DNA nucleotides.", "normal_format": "Which of the following is the enzyme that replaces the RNA nucleotides in a primer with DNA nucleotides?", "question_choices": [ "DNA polymerase III", "DNA polymerase I", "primase", "helicase" ], "question_id": "fs-id1167660304292", "question_text": "Which of the following is the enzyme that replaces the RNA nucleotides in a primer with DNA nucleotides?" }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 0, "ans_text": "A" }, "bloom": null, "hl_context": "The essential steps of replication in eukaryotes are the same as in prokaryotes . Before replication can start , the DNA has to be made available as a template . Eukaryotic DNA is highly supercoiled and packaged , which is facilitated by many proteins , including histone s ( see Structure and Function of Cellular Genomes ) . At the origin of replication , a prereplication complex composed of several proteins , including helicase , forms and recruits other enzymes involved in the initiation of replication , including topoisomerase to relax supercoiling , single-stranded binding protein , RNA primase , and DNA polymerase . <hl> Following initiation of replication , in a process similar to that found in prokaryotes , elongation is facilitated by eukaryotic DNA polymerases . <hl> <hl> The leading strand is continuously synthesized by the eukaryotic polymerase enzyme pol δ , while the lagging strand is synthesized by pol ε . <hl> <hl> A sliding clamp protein holds the DNA polymerase in place so that it does not fall off the DNA . <hl> <hl> The enzyme ribonuclease H ( RNase H ) , instead of a DNA polymerase as in bacteria , removes the RNA primer , which is then replaced with DNA nucleotides . <hl> <hl> The gaps that remain are sealed by DNA ligase . <hl>", "hl_sentences": "Following initiation of replication , in a process similar to that found in prokaryotes , elongation is facilitated by eukaryotic DNA polymerases . The leading strand is continuously synthesized by the eukaryotic polymerase enzyme pol δ , while the lagging strand is synthesized by pol ε . A sliding clamp protein holds the DNA polymerase in place so that it does not fall off the DNA . The enzyme ribonuclease H ( RNase H ) , instead of a DNA polymerase as in bacteria , removes the RNA primer , which is then replaced with DNA nucleotides . The gaps that remain are sealed by DNA ligase .", "question": { "cloze_format": "___ is not involved in the initiation of replication.", "normal_format": "Which of the following is not involved in the initiation of replication?", "question_choices": [ "ligase", "DNA gyrase", "single-stranded binding protein", "primase" ], "question_id": "fs-id1167662519418", "question_text": "Which of the following is not involved in the initiation of replication?" }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 3, "ans_text": "D" }, "bloom": null, "hl_context": "The ends of the linear chromosomes are known as telomere s and consist of noncoding repetitive sequences . The telomeres protect coding sequences from being lost as cells continue to divide . In humans , a six base-pair sequence , TTAGGG , is repeated 100 to 1000 times to form the telomere . <hl> The discovery of the enzyme telomerase ( Figure 11.9 ) clarified our understanding of how chromosome ends are maintained . <hl> Telomerase contains a catalytic part and a built-in RNA template . It attaches to the end of the chromosome , and complementary bases to the RNA template are added on the 3 ’ end of the DNA strand . Once the 3 ’ end of the lagging strand template is sufficiently elongated , DNA polymerase can add the nucleotides complementary to the ends of the chromosomes . In this way , the ends of the chromosomes are replicated . In humans , telomerase is typically active in germ cells and adult stem cells ; it is not active in adult somatic cells and may be associated with the aging of these cells . Eukaryotic microbes including fungi and protozoans also produce telomerase to maintain chromosomal integrity . For her discovery of telomerase and its action , Elizabeth Blackburn ( 1948 – ) received the Nobel Prize for Medicine or Physiology in 2009 . <hl> DNA Replication in Eukaryotes <hl>", "hl_sentences": "The discovery of the enzyme telomerase ( Figure 11.9 ) clarified our understanding of how chromosome ends are maintained . DNA Replication in Eukaryotes", "question": { "cloze_format": "___ is the enzyme involved in DNA replication that is unique to eukaryotes.", "normal_format": "Which of the following enzymes involved in DNA replication is unique to eukaryotes?", "question_choices": [ "helicase", "DNA polymerase", "ligase", "telomerase" ], "question_id": "fs-id1167660177736", "question_text": "Which of the following enzymes involved in DNA replication is unique to eukaryotes?" }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 0, "ans_text": "A" }, "bloom": null, "hl_context": "The essential steps of replication in eukaryotes are the same as in prokaryotes . Before replication can start , the DNA has to be made available as a template . Eukaryotic DNA is highly supercoiled and packaged , which is facilitated by many proteins , including histone s ( see Structure and Function of Cellular Genomes ) . At the origin of replication , a prereplication complex composed of several proteins , including helicase , forms and recruits other enzymes involved in the initiation of replication , including topoisomerase to relax supercoiling , single-stranded binding protein , RNA primase , and DNA polymerase . <hl> Following initiation of replication , in a process similar to that found in prokaryotes , elongation is facilitated by eukaryotic DNA polymerases . <hl> <hl> The leading strand is continuously synthesized by the eukaryotic polymerase enzyme pol δ , while the lagging strand is synthesized by pol ε . <hl> A sliding clamp protein holds the DNA polymerase in place so that it does not fall off the DNA . The enzyme ribonuclease H ( RNase H ) , instead of a DNA polymerase as in bacteria , removes the RNA primer , which is then replaced with DNA nucleotides . The gaps that remain are sealed by DNA ligase .", "hl_sentences": "Following initiation of replication , in a process similar to that found in prokaryotes , elongation is facilitated by eukaryotic DNA polymerases . The leading strand is continuously synthesized by the eukaryotic polymerase enzyme pol δ , while the lagging strand is synthesized by pol ε .", "question": { "cloze_format": "The σ subunit of the RNA polymerase is involved during the ___ stage of bacterial transcription.", "normal_format": "During which stage of bacterial transcription is the σ subunit of the RNA polymerase involved?", "question_choices": [ "initiation", "elongation", "termination", "splicing" ], "question_id": "fs-id1167661271491", "question_text": "During which stage of bacterial transcription is the σ subunit of the RNA polymerase involved?" }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 2, "ans_text": "C" }, "bloom": null, "hl_context": "<hl> The initiation of transcription begins at a promoter , a DNA sequence onto which the transcription machinery binds and initiates transcription . <hl> The nucleotide pair in the DNA double helix that corresponds to the site from which the first 5 ’ RNA nucleotide is transcribed is the initiation site . Nucleotides preceding the initiation site are designated “ upstream , ” whereas nucleotides following the initiation site are called “ downstream ” nucleotides . In most cases , promoters are located just upstream of the genes they regulate . Although promoter sequences vary among bacterial genomes , a few elements are conserved . At the – 10 and – 35 positions within the DNA prior to the initiation site ( designated + 1 ) , there are two promoter consensus sequences , or regions that are similar across all promoters and across various bacterial species . The – 10 consensus sequence , called the TATA box , is TATAAT . The – 35 sequence is recognized and bound by σ .", "hl_sentences": "The initiation of transcription begins at a promoter , a DNA sequence onto which the transcription machinery binds and initiates transcription .", "question": { "cloze_format": "The ___ component is involved in the initiation of transcription.", "normal_format": "Which of the following components is involved in the initiation of transcription?", "question_choices": [ "primer", "origin", "promoter", "start codon" ], "question_id": "fs-id1167663494542", "question_text": "Which of the following components is involved in the initiation of transcription?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 0, "ans_text": "A" }, "bloom": null, "hl_context": "Eukaryotic genes that encode polypeptides are composed of coding sequences called exon s ( ex - on signifies that they are ex pressed ) and intervening sequences called intron s ( int - ron denotes their int ervening role ) . Transcribed RNA sequences corresponding to introns do not encode regions of the functional polypeptide and are removed from the pre-mRNA during processing . It is essential that all of the intron-encoded RNA sequences are completely and precisely removed from a pre-mRNA before protein synthesis so that the exon-encoded RNA sequences are properly joined together to code for a functional polypeptide . If the process errs by even a single nucleotide , the sequences of the rejoined exons would be shifted , and the resulting polypeptide would be nonfunctional . The process of removing intron-encoded RNA sequences and reconnecting those encoded by exons is called RNA splicing and is facilitated by the action of a spliceosome containing small nuclear ribonucleo proteins ( snRNPs ) . Intron-encoded RNA sequences are removed from the pre-mRNA while it is still in the nucleus . Although they are not translated , introns appear to have various functions , including gene regulation and mRNA transport . <hl> On completion of these modifications , the mature transcript , the mRNA that encodes a polypeptide , is transported out of the nucleus , destined for the cytoplasm for translation . <hl> <hl> Introns can be spliced out differently , resulting in various exons being included or excluded from the final mRNA product . <hl> This process is known as alternative splicing . The advantage of alternative splicing is that different types of mRNA transcripts can be generated , all derived from the same DNA sequence . In recent years , it has been shown that some archaea also have the ability to splice their pre-mRNA . <hl> The primary transcript ( also called pre-mRNA ) is first coated with RNA-stabilizing proteins to protect it from degradation while it is processed and exported out of the nucleus . <hl> <hl> The first type of processing begins while the primary transcript is still being synthesized ; a special 7 - methylguanosine nucleotide , called the 5 ’ cap , is added to the 5 ’ end of the growing transcript . <hl> <hl> In addition to preventing degradation , factors involved in subsequent protein synthesis recognize the cap , which helps initiate translation by ribosomes . <hl> <hl> Once elongation is complete , another processing enzyme then adds a string of approximately 200 adenine nucleotides to the 3 ’ end , called the poly-A tail . <hl> <hl> This modification further protects the pre-mRNA from degradation and signals to cellular factors that the transcript needs to be exported to the cytoplasm . <hl>", "hl_sentences": "On completion of these modifications , the mature transcript , the mRNA that encodes a polypeptide , is transported out of the nucleus , destined for the cytoplasm for translation . Introns can be spliced out differently , resulting in various exons being included or excluded from the final mRNA product . The primary transcript ( also called pre-mRNA ) is first coated with RNA-stabilizing proteins to protect it from degradation while it is processed and exported out of the nucleus . The first type of processing begins while the primary transcript is still being synthesized ; a special 7 - methylguanosine nucleotide , called the 5 ’ cap , is added to the 5 ’ end of the growing transcript . In addition to preventing degradation , factors involved in subsequent protein synthesis recognize the cap , which helps initiate translation by ribosomes . Once elongation is complete , another processing enzyme then adds a string of approximately 200 adenine nucleotides to the 3 ’ end , called the poly-A tail . This modification further protects the pre-mRNA from degradation and signals to cellular factors that the transcript needs to be exported to the cytoplasm .", "question": { "cloze_format": "It is not a function of the 5’ cap and 3’ poly-A tail of a mature eukaryotic mRNA molecule ___.", "normal_format": "Which of the following is not a function of the 5’ cap and 3’ poly-A tail of a mature eukaryotic mRNA molecule?", "question_choices": [ "to facilitate splicing", "to prevent mRNA degradation", "to aid export of the mature transcript to the cytoplasm", "to aid ribosome binding to the transcript" ], "question_id": "fs-id1167661440057", "question_text": "Which of the following is not a function of the 5’ cap and 3’ poly-A tail of a mature eukaryotic mRNA molecule?" }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 1, "ans_text": "B" }, "bloom": null, "hl_context": "<hl> Instead of binding to the mRNA at the Shine-Dalgarno sequence , the eukaryotic initiation complex recognizes the 5 ’ cap of the eukaryotic mRNA , then tracks along the mRNA in the 5 ’ to 3 ’ direction until the AUG start codon is recognized . <hl> At this point , the 60S subunit binds to the complex of Met-tRNAi , mRNA , and the 40S subunit . Eukaryotic genes that encode polypeptides are composed of coding sequences called exon s ( ex - on signifies that they are ex pressed ) and intervening sequences called intron s ( int - ron denotes their int ervening role ) . Transcribed RNA sequences corresponding to introns do not encode regions of the functional polypeptide and are removed from the pre-mRNA during processing . <hl> It is essential that all of the intron-encoded RNA sequences are completely and precisely removed from a pre-mRNA before protein synthesis so that the exon-encoded RNA sequences are properly joined together to code for a functional polypeptide . <hl> If the process errs by even a single nucleotide , the sequences of the rejoined exons would be shifted , and the resulting polypeptide would be nonfunctional . The process of removing intron-encoded RNA sequences and reconnecting those encoded by exons is called RNA splicing and is facilitated by the action of a spliceosome containing small nuclear ribonucleo proteins ( snRNPs ) . <hl> Intron-encoded RNA sequences are removed from the pre-mRNA while it is still in the nucleus . <hl> <hl> Although they are not translated , introns appear to have various functions , including gene regulation and mRNA transport . <hl> On completion of these modifications , the mature transcript , the mRNA that encodes a polypeptide , is transported out of the nucleus , destined for the cytoplasm for translation . Introns can be spliced out differently , resulting in various exons being included or excluded from the final mRNA product . This process is known as alternative splicing . The advantage of alternative splicing is that different types of mRNA transcripts can be generated , all derived from the same DNA sequence . In recent years , it has been shown that some archaea also have the ability to splice their pre-mRNA . <hl> The primary transcript ( also called pre-mRNA ) is first coated with RNA-stabilizing proteins to protect it from degradation while it is processed and exported out of the nucleus . <hl> The first type of processing begins while the primary transcript is still being synthesized ; a special 7 - methylguanosine nucleotide , called the 5 ’ cap , is added to the 5 ’ end of the growing transcript . In addition to preventing degradation , factors involved in subsequent protein synthesis recognize the cap , which helps initiate translation by ribosomes . <hl> Once elongation is complete , another processing enzyme then adds a string of approximately 200 adenine nucleotides to the 3 ’ end , called the poly-A tail . <hl> This modification further protects the pre-mRNA from degradation and signals to cellular factors that the transcript needs to be exported to the cytoplasm .", "hl_sentences": "Instead of binding to the mRNA at the Shine-Dalgarno sequence , the eukaryotic initiation complex recognizes the 5 ’ cap of the eukaryotic mRNA , then tracks along the mRNA in the 5 ’ to 3 ’ direction until the AUG start codon is recognized . It is essential that all of the intron-encoded RNA sequences are completely and precisely removed from a pre-mRNA before protein synthesis so that the exon-encoded RNA sequences are properly joined together to code for a functional polypeptide . Intron-encoded RNA sequences are removed from the pre-mRNA while it is still in the nucleus . Although they are not translated , introns appear to have various functions , including gene regulation and mRNA transport . The primary transcript ( also called pre-mRNA ) is first coated with RNA-stabilizing proteins to protect it from degradation while it is processed and exported out of the nucleus . Once elongation is complete , another processing enzyme then adds a string of approximately 200 adenine nucleotides to the 3 ’ end , called the poly-A tail .", "question": { "cloze_format": "Mature mRNA from a eukaryote would not contain a(n) ___ .", "normal_format": "Mature mRNA from a eukaryote would contain each of these features except which of the following?", "question_choices": [ "exon-encoded RNA", "intron-encoded RNA", "5’ cap", "3’ poly-A tail" ], "question_id": "fs-id1167663628980", "question_text": "Mature mRNA from a eukaryote would contain each of these features except which of the following?" }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 1, "ans_text": "B" }, "bloom": null, "hl_context": "Transfer RNAs ( tRNAs ) are structural RNA molecules and , depending on the species , many different types of tRNAs exist in the cytoplasm . Bacterial species typically have between 60 and 90 types . <hl> Serving as adaptors , each tRNA type binds to a specific codon on the mRNA template and adds the corresponding amino acid to the polypeptide chain . <hl> Therefore , tRNAs are the molecules that actually “ translate ” the language of RNA into the language of proteins . As the adaptor molecules of translation , it is surprising that tRNAs can fit so much specificity into such a small package . The tRNA molecule interacts with three factors : aminoacyl tRNA synthetases , ribosomes , and mRNA .", "hl_sentences": "Serving as adaptors , each tRNA type binds to a specific codon on the mRNA template and adds the corresponding amino acid to the polypeptide chain .", "question": { "cloze_format": "The ___ is the name of the three-base sequence in the mRNA that binds to a tRNA molecule.", "normal_format": "Which of the following is the name of the three-base sequence in the mRNA that binds to a tRNA molecule?", "question_choices": [ "P site", "codon", "anticodon", "CCA binding site" ], "question_id": "fs-id1167661352592", "question_text": "Which of the following is the name of the three-base sequence in the mRNA that binds to a tRNA molecule?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 2, "ans_text": "C" }, "bloom": null, "hl_context": "<hl> The termination of translation occurs when a nonsense codon ( UAA , UAG , or UGA ) is encountered for which there is no complementary tRNA . <hl> On aligning with the A site , these nonsense codons are recognized by release factors in prokaryotes and eukaryotes that result in the P-site amino acid detaching from its tRNA , releasing the newly made polypeptide . <hl> The small and large ribosomal subunits dissociate from the mRNA and from each other ; they are recruited almost immediately into another translation initiation complex . <hl> In summary , there are several key features that distinguish prokaryotic gene expression from that seen in eukaryotes . These are illustrated in Figure 11.16 and listed in Figure 11.17 .", "hl_sentences": "The termination of translation occurs when a nonsense codon ( UAA , UAG , or UGA ) is encountered for which there is no complementary tRNA . The small and large ribosomal subunits dissociate from the mRNA and from each other ; they are recruited almost immediately into another translation initiation complex .", "question": { "cloze_format": "The component that is the last to join the initiation complex during the initiation of translation is ___.", "normal_format": "Which component is the last to join the initiation complex during the initiation of translation?", "question_choices": [ "the mRNA molecule", "the small ribosomal subunit", "the large ribosomal subunit", "the initiator tRNA" ], "question_id": "fs-id1167663994698", "question_text": "Which component is the last to join the initiation complex during the initiation of translation?" }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 0, "ans_text": "A" }, "bloom": null, "hl_context": "<hl> In prokaryotes and eukaryotes , the basics of elongation of translation are the same . <hl> <hl> In E . coli , the binding of the 50S ribosomal subunit to produce the intact ribosome forms three functionally important ribosomal sites : The A ( aminoacyl ) site binds incoming charged aminoacyl tRNAs . <hl> <hl> The P ( peptidyl ) site binds charged tRNAs carrying amino acids that have formed peptide bonds with the growing polypeptide chain but have not yet dissociated from their corresponding tRNA . <hl> <hl> The E ( exit ) site releases dissociated tRNAs so that they can be recharged with free amino acids . <hl> There is one notable exception to this assembly line of tRNAs : During initiation complex formation , bacterial fMet − tRNA fMet or eukaryotic Met-tRNAi enters the P site directly without first entering the A site , providing a free A site ready to accept the tRNA corresponding to the first codon after the AUG .", "hl_sentences": "In prokaryotes and eukaryotes , the basics of elongation of translation are the same . In E . coli , the binding of the 50S ribosomal subunit to produce the intact ribosome forms three functionally important ribosomal sites : The A ( aminoacyl ) site binds incoming charged aminoacyl tRNAs . The P ( peptidyl ) site binds charged tRNAs carrying amino acids that have formed peptide bonds with the growing polypeptide chain but have not yet dissociated from their corresponding tRNA . The E ( exit ) site releases dissociated tRNAs so that they can be recharged with free amino acids .", "question": { "cloze_format": "During elongation in translation, the ribosomal site to which an incoming charged tRNA molecule binds is the ___.", "normal_format": "During elongation in translation, to which ribosomal site does an incoming charged tRNA molecule bind?", "question_choices": [ "A site", "P site", "E site", "B site" ], "question_id": "fs-id1167663628445", "question_text": "During elongation in translation, to which ribosomal site does an incoming charged tRNA molecule bind?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 1, "ans_text": "B" }, "bloom": null, "hl_context": "The termination of translation occurs when a nonsense codon ( UAA , UAG , or UGA ) is encountered for which there is no complementary tRNA . <hl> On aligning with the A site , these nonsense codons are recognized by release factors in prokaryotes and eukaryotes that result in the P-site amino acid detaching from its tRNA , releasing the newly made polypeptide . <hl> The small and large ribosomal subunits dissociate from the mRNA and from each other ; they are recruited almost immediately into another translation initiation complex . In summary , there are several key features that distinguish prokaryotic gene expression from that seen in eukaryotes . These are illustrated in Figure 11.16 and listed in Figure 11.17 . <hl> Whereas 61 of the 64 possible triplets code for amino acids , three of the 64 codons do not code for an amino acid ; they terminate protein synthesis , releasing the polypeptide from the translation machinery . <hl> <hl> These are called stop codon s or nonsense codon s . <hl> Another codon , AUG , also has a special function . In addition to specifying the amino acid methionine , it also typically serves as the start codon to initiate translation . The reading frame , the way nucleotides in mRNA are grouped into codons , for translation is set by the AUG start codon near the 5 ’ end of the mRNA . Each set of three nucleotides following this start codon is a codon in the mRNA message .", "hl_sentences": "On aligning with the A site , these nonsense codons are recognized by release factors in prokaryotes and eukaryotes that result in the P-site amino acid detaching from its tRNA , releasing the newly made polypeptide . Whereas 61 of the 64 possible triplets code for amino acids , three of the 64 codons do not code for an amino acid ; they terminate protein synthesis , releasing the polypeptide from the translation machinery . These are called stop codon s or nonsense codon s .", "question": { "cloze_format": "When the ribosome reaches a nonsense codon, ___ occurs.", "normal_format": "When the ribosome reaches a nonsense codon, which of the following occurs?", "question_choices": [ "a methionine is incorporated", "the polypeptide is released", "a peptide bond forms", "the A site binds to a charged tRNA" ], "question_id": "fs-id1167663548118", "question_text": "When the ribosome reaches a nonsense codon, which of the following occurs?" }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 1, "ans_text": "B" }, "bloom": null, "hl_context": "Point mutations may have a wide range of effects on protein function ( Figure 11.18 ) . As a consequence of the degeneracy of the genetic code , a point mutation will commonly result in the same amino acid being incorporated into the resulting polypeptide despite the sequence change . This change would have no effect on the protein ’ s structure , and is thus called a silent mutation . A missense mutation results in a different amino acid being incorporated into the resulting polypeptide . The effect of a missense mutation depends on how chemically different the new amino acid is from the wild-type amino acid . The location of the changed amino acid within the protein also is important . For example , if the changed amino acid is part of the enzyme ’ s active site , then the effect of the missense mutation may be significant . Many missense mutations result in proteins that are still functional , at least to some degree . Sometimes the effects of missense mutations may be only apparent under certain environmental conditions ; such missense mutations are called conditional mutation s . Rarely , a missense mutation may be beneficial . Under the right environmental conditions , this type of mutation may give the organism that harbors it a selective advantage . <hl> Yet another type of point mutation , called a nonsense mutation , converts a codon encoding an amino acid ( a sense codon ) into a stop codon ( a nonsense codon ) . <hl> Nonsense mutations result in the synthesis of proteins that are shorter than the wild type and typically not functional .", "hl_sentences": "Yet another type of point mutation , called a nonsense mutation , converts a codon encoding an amino acid ( a sense codon ) into a stop codon ( a nonsense codon ) .", "question": { "cloze_format": "___ is a change in the sequence that leads to formation of a stop codon.", "normal_format": "Which of the following is a change in the sequence that leads to formation of a stop codon?", "question_choices": [ "missense mutation", "nonsense mutation", "silent mutation", "deletion mutation" ], "question_id": "fs-id1167662879138", "question_text": "Which of the following is a change in the sequence that leads to formation of a stop codon?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 2, "ans_text": "C" }, "bloom": null, "hl_context": "<hl> Nonionizing radiation , like ultraviolet light , is not energetic enough to initiate these types of chemical changes . <hl> <hl> However , nonionizing radiation can induce dimer formation between two adjacent pyrimidine bases , commonly two thymines , within a nucleotide strand . <hl> During thymine dimer formation , the two adjacent thymines become covalently linked and , if left unrepaired , both DNA replication and transcription are stalled at this point . DNA polymerase may proceed and replicate the dimer incorrectly , potentially leading to frameshift or point mutations .", "hl_sentences": "Nonionizing radiation , like ultraviolet light , is not energetic enough to initiate these types of chemical changes . However , nonionizing radiation can induce dimer formation between two adjacent pyrimidine bases , commonly two thymines , within a nucleotide strand .", "question": { "cloze_format": "The formation of pyrimidine dimers results from ___ .", "normal_format": "The formation of pyrimidine dimers results from which of the following?", "question_choices": [ "spontaneous errors by DNA polymerase", "exposure to gamma radiation", "exposure to ultraviolet radiation", "exposure to intercalating agents" ], "question_id": "fs-id1167660170738", "question_text": "The formation of pyrimidine dimers results from which of the following?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 3, "ans_text": "D" }, "bloom": null, "hl_context": "<hl> Deletions and insertions also cause various effects . <hl> <hl> Because codons are triplets of nucleotides , insertions or deletions in groups of three nucleotides may lead to the insertion or deletion of one or more amino acids and may not cause significant effects on the resulting protein ’ s functionality . <hl> <hl> However , frameshift mutation s , caused by insertions or deletions of a number of nucleotides that are not a multiple of three are extremely problematic because a shift in the reading frame results ( Figure 11.18 ) . <hl> Because ribosomes read the mRNA in triplet codons , frameshift mutations can change every amino acid after the point of the mutation . The new reading frame may also include a stop codon before the end of the coding sequence . Consequently , proteins made from genes containing frameshift mutations are nearly always nonfunctional .", "hl_sentences": "Deletions and insertions also cause various effects . Because codons are triplets of nucleotides , insertions or deletions in groups of three nucleotides may lead to the insertion or deletion of one or more amino acids and may not cause significant effects on the resulting protein ’ s functionality . However , frameshift mutation s , caused by insertions or deletions of a number of nucleotides that are not a multiple of three are extremely problematic because a shift in the reading frame results ( Figure 11.18 ) .", "question": { "cloze_format": "___ is an example of a frameshift mutation.", "normal_format": "Which of the following is an example of a frameshift mutation?", "question_choices": [ "a deletion of a codon", "missense mutation", "silent mutation", "deletion of one nucleotide" ], "question_id": "fs-id1167662885968", "question_text": "Which of the following is an example of a frameshift mutation?" }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 0, "ans_text": "A" }, "bloom": null, "hl_context": "<hl> The direct repair ( also called light repair ) of thymine dimers occurs through the process of photoreactivation in the presence of visible light . <hl> <hl> An enzyme called photolyase recognizes the distortion in the DNA helix caused by the thymine dimer and binds to the dimer . <hl> <hl> Then , in the presence of visible light , the photolyase enzyme changes conformation and breaks apart the thymine dimer , allowing the thymines to again correctly base pair with the adenines on the complementary strand . <hl> Photoreactivation appears to be present in all organisms , with the exception of placental mammals , including humans . Photoreactivation is particularly important for organisms chronically exposed to ultraviolet radiation , like plants , photosynthetic bacteria , algae , and corals , to prevent the accumulation of mutations caused by thymine dimer formation .", "hl_sentences": "The direct repair ( also called light repair ) of thymine dimers occurs through the process of photoreactivation in the presence of visible light . An enzyme called photolyase recognizes the distortion in the DNA helix caused by the thymine dimer and binds to the dimer . Then , in the presence of visible light , the photolyase enzyme changes conformation and breaks apart the thymine dimer , allowing the thymines to again correctly base pair with the adenines on the complementary strand .", "question": { "cloze_format": "___ is the type of DNA repair in which thymine dimers are directly broken down by the enzyme photolyase.", "normal_format": "Which of the following is the type of DNA repair in which thymine dimers are directly broken down by the enzyme photolyase?", "question_choices": [ "direct repair", "nucleotide excision repair", "mismatch repair", "proofreading" ], "question_id": "fs-id1167662907611", "question_text": "Which of the following is the type of DNA repair in which thymine dimers are directly broken down by the enzyme photolyase?" }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 1, "ans_text": "B" }, "bloom": null, "hl_context": "<hl> The Ames test , developed by Bruce Ames ( 1928 – ) in the 1970s , is a method that uses bacteria for rapid , inexpensive screening of the carcinogenic potential of new chemical compounds . <hl> The test measures the mutation rate associated with exposure to the compound , which , if elevated , may indicate that exposure to this compound is associated with greater cancer risk . The Ames test uses as the test organism a strain of Salmonella typhimurium that is a histidine auxotroph , unable to synthesize its own histidine because of a mutation in an essential gene required for its synthesis . <hl> After exposure to a potential mutagen , these bacteria are plated onto a medium lacking histidine , and the number of mutants regaining the ability to synthesize histidine is recorded and compared with the number of such mutants that arise in the absence of the potential mutagen ( Figure 11.25 ) . <hl> <hl> Chemicals that are more mutagenic will bring about more mutants with restored histidine synthesis in the Ames test . <hl> Because many chemicals are not directly mutagenic but are metabolized to mutagenic forms by liver enzymes , rat liver extract is commonly included at the start of this experiment to mimic liver metabolism . After the Ames test is conducted , compounds identified as mutagenic are further tested for their potential carcinogenic properties by using other models , including animal models like mice and rats .", "hl_sentences": "The Ames test , developed by Bruce Ames ( 1928 – ) in the 1970s , is a method that uses bacteria for rapid , inexpensive screening of the carcinogenic potential of new chemical compounds . After exposure to a potential mutagen , these bacteria are plated onto a medium lacking histidine , and the number of mutants regaining the ability to synthesize histidine is recorded and compared with the number of such mutants that arise in the absence of the potential mutagen ( Figure 11.25 ) . Chemicals that are more mutagenic will bring about more mutants with restored histidine synthesis in the Ames test .", "question": { "cloze_format": "Regarding the Ames test it is true that ___.", "normal_format": "Which of the following regarding the Ames test is true?", "question_choices": [ "It is used to identify newly formed auxotrophic mutants.", "It is used to identify mutants with restored biosynthetic activity.", "It is used to identify spontaneous mutants.", "It is used to identify mutants lacking photoreactivation activity." ], "question_id": "fs-id1167662483823", "question_text": "Which of the following regarding the Ames test is true?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 2, "ans_text": "C" }, "bloom": null, "hl_context": "Viruses that infect bacteria ( bacteriophages ) may also move short pieces of chromosomal DNA from one bacterium to another in a process called transduction ( see Figure 6.9 ) . <hl> Recall that in generalized transduction , any piece of chromosomal DNA may be transferred to a new host cell by accidental packaging of chromosomal DNA into a phage head during phage assembly . <hl> <hl> By contrast , specialized transduction results from the imprecise excision of a lysogenic prophage from the bacterial chromosome such that it carries with it a piece of the bacterial chromosome from either side of the phage ’ s integration site to a new host cell . <hl> As a result , the host may acquire new properties . This process is called lysogenic conversion . Of medical significance , a lysogenic phage may carry with it a virulence gene to its new host . Once inserted into the new host ’ s chromosome , the new host may gain pathogenicity . Several pathogenic bacteria , including Corynebacterium diphtheriae ( the causative agent of diphtheria ) and Clostridium botulinum ( the causative agent of botulism ) , are virulent because of the introduction of toxin-encoding genes by lysogenic bacteriophages , affirming the clinical relevance of transduction in the exchange of genes involved in infectious disease . Archaea have their own viruses that translocate genetic material from one individual to another .", "hl_sentences": "Recall that in generalized transduction , any piece of chromosomal DNA may be transferred to a new host cell by accidental packaging of chromosomal DNA into a phage head during phage assembly . By contrast , specialized transduction results from the imprecise excision of a lysogenic prophage from the bacterial chromosome such that it carries with it a piece of the bacterial chromosome from either side of the phage ’ s integration site to a new host cell .", "question": { "cloze_format": "___ is the mechanism by which improper excision of a prophage from a bacterial chromosome results in packaging of bacterial genes near the integration site into a phage head.", "normal_format": "Which is the mechanism by which improper excision of a prophage from a bacterial chromosome results in packaging of bacterial genes near the integration site into a phage head?", "question_choices": [ "conjugation", "generalized transduction", "specialized transduction", "transformation" ], "question_id": "fs-id1167663653549", "question_text": "Which is the mechanism by which improper excision of a prophage from a bacterial chromosome results in packaging of bacterial genes near the integration site into a phage head?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 3, "ans_text": "D" }, "bloom": null, "hl_context": "<hl> In transformation , the prokaryote takes up naked DNA found in its environment and that is derived from other cells that have lysed on death and released their contents , including their genome , into the environment . <hl> Many bacteria are naturally competent , meaning that they actively bind to environmental DNA , transport it across their cell envelopes into their cytoplasm , and make it single stranded . Typically , double-stranded foreign DNA within cells is destroyed by nucleases as a defense against viral infection . However , these nucleases are usually ineffective against single-stranded DNA , so this single-stranded DNA within the cell has the opportunity to recombine into the bacterial genome . A molecule of DNA that contains fragments of DNA from different organisms is called recombinant DNA . ( Recombinant DNA will be discussed in more detail in Microbes and the Tools of Genetic Engineering . ) If the bacterium incorporates the new DNA into its own genome through recombination , the bacterial cell may gain new phenotypic properties . For example , if a nonpathogenic bacterium takes up DNA for a toxin gene from a pathogen and then incorporates it into its chromosome , it , too , may become pathogenic . Plasmid DNA may also be taken up by competent bacteria and confer new properties to the cell . Overall , transformation in nature is a relatively inefficient process because environmental DNA levels are low because of the activity of nucleases that are also released during cellular lysis . Additionally , genetic recombination is inefficient at incorporating new DNA sequences into the genome .", "hl_sentences": "In transformation , the prokaryote takes up naked DNA found in its environment and that is derived from other cells that have lysed on death and released their contents , including their genome , into the environment .", "question": { "cloze_format": "___ refers to the uptake of naked DNA from the surrounding environment.", "normal_format": "Which of the following refers to the uptake of naked DNA from the surrounding environment?", "question_choices": [ "conjugation", "generalized transduction", "specialized transduction", "transformation" ], "question_id": "fs-id1167661743528", "question_text": "Which of the following refers to the uptake of naked DNA from the surrounding environment?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 0, "ans_text": "A" }, "bloom": null, "hl_context": "<hl> In conjugation , DNA is directly transferred from one prokaryote to another by means of a conjugation pilus , which brings the organisms into contact with one another . <hl> <hl> In E . coli , the genes encoding the ability to conjugate are located on a bacterial plasmid called the F plasmid , also known as the fertility factor , and the conjugation pilus is called the F pilus . <hl> The F-plasmid genes encode both the proteins composing the F pilus and those involved in rolling circle replication of the plasmid . Cells containing the F plasmid , capable of forming an F pilus , are called F + cell s or donor cell s , and those lacking an F plasmid are called F − cell s or recipient cell s .", "hl_sentences": "In conjugation , DNA is directly transferred from one prokaryote to another by means of a conjugation pilus , which brings the organisms into contact with one another . In E . coli , the genes encoding the ability to conjugate are located on a bacterial plasmid called the F plasmid , also known as the fertility factor , and the conjugation pilus is called the F pilus .", "question": { "cloze_format": "The F plasmid is involved in the process of ___ .", "normal_format": "The F plasmid is involved in which of the following processes?", "question_choices": [ "conjugation", "transduction", "transposition", "transformation" ], "question_id": "fs-id1167663963908", "question_text": "The F plasmid is involved in which of the following processes?" }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 0, "ans_text": "A" }, "bloom": null, "hl_context": "Transposons may carry with them additional genes , moving these genes from one location to another with them . For example , bacterial transposons can relocate antibiotic resistance genes , moving them from chromosomes to plasmids . <hl> This mechanism has been shown to be responsible for the colocalization of multiple antibiotic resistance genes on a single R plasmid in Shigella strains causing bacterial dysentery . <hl> <hl> Such an R plasmid can then be easily transferred among a bacterial population through the process of conjugation . <hl>", "hl_sentences": "This mechanism has been shown to be responsible for the colocalization of multiple antibiotic resistance genes on a single R plasmid in Shigella strains causing bacterial dysentery . Such an R plasmid can then be easily transferred among a bacterial population through the process of conjugation .", "question": { "cloze_format": "___ refers to the mechanism of horizontal gene transfer naturally responsible for the spread of antibiotic resistance genes within a bacterial population.", "normal_format": "Which of the following refers to the mechanism of horizontal gene transfer naturally responsible for the spread of antibiotic resistance genes within a bacterial population?", "question_choices": [ "conjugation", "generalized transduction", "specialized transduction", "transformation" ], "question_id": "fs-id1167663637654", "question_text": "Which of the following refers to the mechanism of horizontal gene transfer naturally responsible for the spread of antibiotic resistance genes within a bacterial population?" }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 1, "ans_text": "B" }, "bloom": null, "hl_context": "Prokaryotic operons are commonly controlled by the binding of repressors to operator regions , thereby preventing the transcription of the structural genes . Such operons are classified as either repressible operon s or inducible operons . <hl> Repressible operons , like the tryptophan ( trp ) operon , typically contain genes encoding enzymes required for a biosynthetic pathway . <hl> <hl> As long as the product of the pathway , like tryptophan , continues to be required by the cell , a repressible operon will continue to be expressed . <hl> However , when the product of the biosynthetic pathway begins to accumulate in the cell , removing the need for the cell to continue to make more , the expression of the operon is repressed . Conversely , inducible operon s , like the lac operon of E . coli , often contain genes encoding enzymes in a pathway involved in the metabolism of a specific substrate like lactose . These enzymes are only required when that substrate is available , thus expression of the operons is typically induced only in the presence of the substrate .", "hl_sentences": "Repressible operons , like the tryptophan ( trp ) operon , typically contain genes encoding enzymes required for a biosynthetic pathway . As long as the product of the pathway , like tryptophan , continues to be required by the cell , a repressible operon will continue to be expressed .", "question": { "cloze_format": "An operon of genes encoding enzymes in a biosynthetic pathway is likely to be ___.", "normal_format": "An operon of genes encoding enzymes in a biosynthetic pathway is likely to be which of the following?", "question_choices": [ "inducible", "repressible", "constitutive", "monocistronic" ], "question_id": "fs-id1167661296201", "question_text": "An operon of genes encoding enzymes in a biosynthetic pathway is likely to be which of the following?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 2, "ans_text": "C" }, "bloom": null, "hl_context": "In prokaryotes , there are examples of operons whose gene products are required rather consistently and whose expression , therefore , is unregulated . <hl> Such operons are constitutively expressed , meaning they are transcribed and translated continuously to provide the cell with constant intermediate levels of the protein products . <hl> Such genes encode enzymes involved in housekeeping functions required for cellular maintenance , including DNA replication , repair , and expression , as well as enzymes involved in core metabolism . In contrast , there are other prokaryotic operons that are expressed only when needed and are regulated by repressors , activators , and inducers .", "hl_sentences": "Such operons are constitutively expressed , meaning they are transcribed and translated continuously to provide the cell with constant intermediate levels of the protein products .", "question": { "cloze_format": "An operon encoding genes that are transcribed and translated continuously to provide the cell with constant intermediate levels of the protein products is said to be ___.", "normal_format": "An operon encoding genes that are transcribed and translated continuously to provide the cell with constant intermediate levels of the protein products is said to be which of the following?", "question_choices": [ "repressible", "inducible", "constitutive", "activated" ], "question_id": "fs-id1167663631279", "question_text": "An operon encoding genes that are transcribed and translated continuously to provide the cell with constant intermediate levels of the protein products is said to be which of the following?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 0, "ans_text": "A" }, "bloom": null, "hl_context": "<hl> The lac operon is an example of an inducible operon that is also subject to activation in the absence of glucose ( Figure 11.34 ) . <hl> The lac operon encodes three structural genes necessary to acquire and process the disaccharide lactose from the environment , breaking it down into the simple sugars glucose and galactose . <hl> For the lac operon to be expressed , lactose must be present . <hl> <hl> This makes sense for the cell because it would be energetically wasteful to create the enzymes to process lactose if lactose was not available . <hl>", "hl_sentences": "The lac operon is an example of an inducible operon that is also subject to activation in the absence of glucose ( Figure 11.34 ) . For the lac operon to be expressed , lactose must be present . This makes sense for the cell because it would be energetically wasteful to create the enzymes to process lactose if lactose was not available .", "question": { "cloze_format": "The conditions that lead to maximal expression of the lac operon are ___ .", "normal_format": "Which of the following conditions leads to maximal expression of the lac operon?", "question_choices": [ "lactose present, glucose absent", "lactose present, glucose present", "lactose absent, glucose absent", "lactose absent, glucose present" ], "question_id": "fs-id1167661750541", "question_text": "Which of the following conditions leads to maximal expression of the lac operon?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 2, "ans_text": "C" }, "bloom": null, "hl_context": "<hl> In eukaryotes , the DNA molecules or associated histones can be chemically modified in such a way as to influence transcription ; this is called epigenetic regulation . <hl> Methylation of certain cytosine nucleotides in DNA in response to environmental factors has been shown to influence use of such DNA for transcription , with DNA methylation commonly correlating to lowered levels of gene expression . Additionally , in response to environmental factors , histone proteins for packaging DNA can also be chemically modified in multiple ways , including acetylation and deacetylation , influencing the packaging state of DNA and thus affecting the availability of loosely wound DNA for transcription . These chemical modifications can sometimes be maintained through multiple rounds of cell division , making at least some of these epigenetic changes heritable .", "hl_sentences": "In eukaryotes , the DNA molecules or associated histones can be chemically modified in such a way as to influence transcription ; this is called epigenetic regulation .", "question": { "cloze_format": "(The) ___ is/are a type of regulation of gene expression unique to eukaryotes.", "normal_format": "Which of the following is a type of regulation of gene expression unique to eukaryotes?", "question_choices": [ "attenuation", "use of alternate σ factor", "chemical modification of histones", "alarmones" ], "question_id": "fs-id1167663959876", "question_text": "Which of the following is a type of regulation of gene expression unique to eukaryotes?" }, "references_are_paraphrase": 0 } ]
11
11.1 The Functions of Genetic Material Learning Objectives Explain the two functions of the genome Explain the meaning of the central dogma of molecular biology Differentiate between genotype and phenotype and explain how environmental factors influence phenotype Clinical Focus Part 1 Mark is 60-year-old software engineer who suffers from type II diabetes, which he monitors and keeps under control largely through diet and exercise. One spring morning, while doing some gardening, he scraped his lower leg while walking through blackberry brambles. He continued working all day in the yard and did not bother to clean the wound and treat it with antibiotic ointment until later that evening. For the next 2 days, his leg became increasingly red, swollen, and warm to the touch. It was sore not only on the surface, but deep in the muscle. After 24 hours, Mark developed a fever and stiffness in the affected leg. Feeling increasingly weak, he called a neighbor, who drove him to the emergency department. Did Mark wait too long to seek medical attention? At what point do his signs and symptoms warrant seeking medical attention? What types of infections or other conditions might be responsible for Mark’s symptoms? Jump to the next Clinical Focus box. DNA serves two essential functions that deal with cellular information. First, DNA is the genetic material responsible for inheritance and is passed from parent to offspring for all life on earth. To preserve the integrity of this genetic information, DNA must be replicated with great accuracy, with minimal errors that introduce changes to the DNA sequence. A genome contains the full complement of DNA within a cell and is organized into smaller, discrete units called gene s that are arranged on chromosome s and plasmid s. The second function of DNA is to direct and regulate the construction of the proteins necessary to a cell for growth and reproduction in a particular cellular environment. A gene is composed of DNA that is “read” or transcribed to produce an RNA molecule during the process of transcription . One major type of RNA molecule, called messenger RNA (mRNA), provides the information for the ribosome to catalyze protein synthesis in a process called translation . The processes of transcription and translation are collectively referred to as gene expression . Gene expression is the synthesis of a specific protein with a sequence of amino acids that is encoded in the gene. The flow of genetic information from DNA to RNA to protein is described by the central dogma ( Figure 11.2 ). This central dogma of molecular biology further elucidates the mechanism behind Beadle and Tatum ’s “one gene-one enzyme” hypothesis (see Using Microorganisms to Discover the Secrets of Life ). Each of the processes of replication, transcription, and translation includes the stages of 1) initiation, 2) elongation (polymerization), and 3) termination. These stages will be described in more detail in this chapter. A cell’s genotype is the full collection of genes it contains, whereas its phenotype is the set of observable characteristics that result from those genes. The phenotype is the product of the array of proteins being produced by the cell at a given time, which is influenced by the cell’s genotype as well as interactions with the cell’s environment. Genes code for proteins that have functions in the cell. Production of a specific protein encoded by an individual gene often results in a distinct phenotype for the cell compared with the phenotype without that protein. For this reason, it is also common to refer to the genotype of an individual gene and its phenotype. Although a cell’s genotype remains constant, not all genes are used to direct the production of their proteins simultaneously. Cells carefully regulate expression of their genes, only using genes to make specific proteins when those proteins are needed ( Figure 11.3 ). Check Your Understanding What are the two functions of DNA? Distinguish between the genotype and phenotype of a cell. How can cells have the same genotype but differ in their phenotype? Eye on Ethics Use and Abuse of Genome Data Why can some humans harbor opportunistic pathogens like Haemophilus influenzae , Staphylococcus aureus , or Streptococcus pyogenes , in their upper respiratory tracts but remain asymptomatic carriers, while other individuals become seriously ill when infected? There is evidence suggesting that differences in susceptibility to infection between patients may be a result, at least in part, of genetic differences between human hosts. For example, genetic differences in human leukocyte antigens (HLAs) and red blood cell antigens among hosts have been implicated in different immune responses and resulting disease progression from infection with H. influenzae . Because the genetic interplay between pathogen and host may contribute to disease outcomes, understanding differences in genetic makeup between individuals may be an important clinical tool. Ecological genomics is a relatively new field that seeks to understand how the genotypes of different organisms interact with each other in nature. The field answers questions about how gene expression of one organism affects gene expression of another. Medical applications of ecological genomics will focus on how pathogens interact with specific individuals, as opposed to humans in general. Such analyses would allow medical professionals to use knowledge of an individual’s genotype to apply more individualized plans for treatment and prevention of disease. With the advent of next-generation sequencing, it is relatively easy to obtain the entire genomic sequences of pathogens; a bacterial genome can be sequenced in as little as a day. 1 The speed and cost of sequencing the human genome has also been greatly reduced and, already, individuals can submit samples to receive extensive reports on their personal genetic traits, including ancestry and carrier status for various genetic diseases. As sequencing technologies progress further, such services will continue to become less expensive, more extensive, and quicker. 1 D.J. Edwards, K.E. Holt. “Beginner’s Guide to Comparative Bacterial Genome Analysis Using Next-Generation Sequence Data.” Microbial Informatics and Experimentation 3 no. 1 (2013):2. However, as this day quickly approaches, there are many ethical concerns with which society must grapple. For example, should genome sequencing be a standard practice for everybody? Should it be required by law or by employers if it will lower health-care costs? If one refuses genome sequencing, does he or she forfeit his or her right to health insurance coverage? For what purposes should the data be used? Who should oversee proper use of these data? If genome sequencing reveals predisposition to a particular disease, do insurance companies have the right to increase rates? Will employers treat an employee differently? Knowing that environmental influences also affect disease development, how should the data on the presence of a particular disease-causing allele in an individual be used ethically? The Genetic Information Nondiscrimination Act of 2008 (GINA) currently prohibits discriminatory practices based on genetic information by both health insurance companies and employers. However, GINA does not cover life, disability, or long-term care insurance policies. Clearly, all members of society must continue to engage in conversations about these issues so that such genomic data can be used to improve health care while simultaneously protecting an individual’s rights. 11.2 DNA Replication Learning Objectives Explain the meaning of semiconservative DNA replication Explain why DNA replication is bidirectional and includes both a leading and lagging strand Explain why Okazaki fragments are formed Describe the process of DNA replication and the functions of the enzymes involved Identify the differences between DNA replication in bacteria and eukaryotes Explain the process of rolling circle replication The elucidation of the structure of the double helix by James Watson and Francis Crick in 1953 provided a hint as to how DNA is copied during the process of replication . Separating the strands of the double helix would provide two templates for the synthesis of new complementary strands, but exactly how new DNA molecules were constructed was still unclear. In one model, semiconservative replication , the two strands of the double helix separate during DNA replication, and each strand serves as a template from which the new complementary strand is copied; after replication, each double-stranded DNA includes one parental or “old” strand and one “new” strand. There were two competing models also suggested: conservative and dispersive, which are shown in Figure 11.4 . Matthew Meselson (1930–) and Franklin Stahl (1929–) devised an experiment in 1958 to test which of these models correctly represents DNA replication ( Figure 11.5 ). They grew E. coli for several generations in a medium containing a “heavy” isotope of nitrogen ( 15 N) that was incorporated into nitrogenous bases and, eventually, into the DNA. This labeled the parental DNA. The E. coli culture was then shifted into a medium containing 14 N and allowed to grow for one generation. The cells were harvested and the DNA was isolated. The DNA was separated by ultracentrifugation, during which the DNA formed bands according to its density. DNA grown in 15 N would be expected to form a band at a higher density position than that grown in 14 N. Meselson and Stahl noted that after one generation of growth in 14 N, the single band observed was intermediate in position in between DNA of cells grown exclusively in 15 N or 14 N. This suggested either a semiconservative or dispersive mode of replication. Some cells were allowed to grow for one more generation in 14 N and spun again. The DNA harvested from cells grown for two generations in 14 N formed two bands: one DNA band was at the intermediate position between 15 N and 14 N, and the other corresponded to the band of 14 N DNA. These results could only be explained if DNA replicates in a semiconservative manner. Therefore, the other two models were ruled out. As a result of this experiment, we now know that during DNA replication, each of the two strands that make up the double helix serves as a template from which new strands are copied. The new strand will be complementary to the parental or “old” strand. The resulting DNA molecules have the same sequence and are divided equally into the two daughter cells. Check Your Understanding What would have been the conclusion of Meselson and Stahl’s experiment if, after the first generation, they had found two bands of DNA? DNA Replication in Bacteria DNA replication has been well studied in bacteria primarily because of the small size of the genome and the mutants that are available. E. coli has 4.6 million base pairs (Mbp) in a single circular chromosome and all of it is replicated in approximately 42 minutes, starting from a single origin of replication and proceeding around the circle bidirectionally (i.e., in both directions). This means that approximately 1000 nucleotides are added per second. The process is quite rapid and occurs with few errors. DNA replication uses a large number of proteins and enzymes ( Table 11.1 ). One of the key players is the enzyme DNA polymerase , also known as DNA pol. In bacteria, three main types of DNA polymerases are known: DNA pol I, DNA pol II, and DNA pol III. It is now known that DNA pol III is the enzyme required for DNA synthesis; DNA pol I and DNA pol II are primarily required for repair. DNA pol III adds deoxyribonucleotides each complementary to a nucleotide on the template strand, one by one to the 3’-OH group of the growing DNA chain. The addition of these nucleotides requires energy. This energy is present in the bonds of three phosphate groups attached to each nucleotide (a triphosphate nucleotide), similar to how energy is stored in the phosphate bonds of adenosine triphosphate (ATP) ( Figure 11.6 ). When the bond between the phosphates is broken and diphosphate is released, the energy released allows for the formation of a covalent phosphodiester bond by dehydration synthesis between the incoming nucleotide and the free 3’-OH group on the growing DNA strand. Initiation The initiation of replication occurs at specific nucleotide sequence called the origin of replication , where various proteins bind to begin the replication process. E. coli has a single origin of replication (as do most prokaryotes), called oriC , on its one chromosome. The origin of replication is approximately 245 base pairs long and is rich in adenine-thymine (AT) sequences. Some of the proteins that bind to the origin of replication are important in making single-stranded regions of DNA accessible for replication. Chromosomal DNA is typically wrapped around histones (in eukaryotes and archaea) or histone-like proteins (in bacteria), and is supercoiled , or extensively wrapped and twisted on itself. This packaging makes the information in the DNA molecule inaccessible. However, enzymes called topoisomerases change the shape and supercoiling of the chromosome. For bacterial DNA replication to begin, the supercoiled chromosome is relaxed by topoisomerase II , also called DNA gyrase . An enzyme called helicase then separates the DNA strands by breaking the hydrogen bonds between the nitrogenous base pairs. Recall that AT sequences have fewer hydrogen bonds and, hence, have weaker interactions than guanine-cytosine (GC) sequences. These enzymes require ATP hydrolysis. As the DNA opens up, Y-shaped structures called replication forks are formed. Two replication forks are formed at the origin of replication, allowing for bidirectional replication and formation of a structure that looks like a bubble when viewed with a transmission electron microscope; as a result, this structure is called a replication bubble . The DNA near each replication fork is coated with single-stranded binding proteins to prevent the single-stranded DNA from rewinding into a double helix. Once single-stranded DNA is accessible at the origin of replication, DNA replication can begin. However, DNA pol III is able to add nucleotides only in the 5’ to 3’ direction (a new DNA strand can be only extended in this direction). This is because DNA polymerase requires a free 3’-OH group to which it can add nucleotides by forming a covalent phosphodiester bond between the 3’-OH end and the 5’ phosphate of the next nucleotide. This also means that it cannot add nucleotides if a free 3’-OH group is not available, which is the case for a single strand of DNA. The problem is solved with the help of an RNA sequence that provides the free 3’-OH end. Because this sequence allows the start of DNA synthesis, it is appropriately called the primer . The primer is five to 10 nucleotides long and complementary to the parental or template DNA. It is synthesized by RNA primase , which is an RNA polymerase . Unlike DNA polymerases, RNA polymerases do not need a free 3’-OH group to synthesize an RNA molecule. Now that the primer provides the free 3’-OH group, DNA polymerase III can now extend this RNA primer, adding DNA nucleotides one by one that are complementary to the template strand ( Figure 11.4 ). Elongation During elongation in DNA replication , the addition of nucleotides occurs at its maximal rate of about 1000 nucleotides per second. DNA polymerase III can only extend in the 5’ to 3’ direction, which poses a problem at the replication fork. The DNA double helix is antiparallel; that is, one strand is oriented in the 5’ to 3’ direction and the other is oriented in the 3’ to 5’ direction (see Structure and Function of DNA ). During replication, one strand, which is complementary to the 3’ to 5’ parental DNA strand, is synthesized continuously toward the replication fork because polymerase can add nucleotides in this direction. This continuously synthesized strand is known as the leading strand . The other strand, complementary to the 5’ to 3’ parental DNA, grows away from the replication fork, so the polymerase must move back toward the replication fork to begin adding bases to a new primer, again in the direction away from the replication fork. It does so until it bumps into the previously synthesized strand and then it moves back again ( Figure 11.7 ). These steps produce small DNA sequence fragments known as Okazaki fragments , each separated by RNA primer. Okazaki fragments are named after the Japanese research team and married couple Reiji and Tsuneko Okazaki , who first discovered them in 1966. The strand with the Okazaki fragments is known as the lagging strand , and its synthesis is said to be discontinuous. The leading strand can be extended from one primer alone, whereas the lagging strand needs a new primer for each of the short Okazaki fragments. The overall direction of the lagging strand will be 3’ to 5’, and that of the leading strand 5’ to 3’. A protein called the sliding clamp holds the DNA polymerase in place as it continues to add nucleotides. The sliding clamp is a ring-shaped protein that binds to the DNA and holds the polymerase in place. Beyond its role in initiation, topoisomerase also prevents the overwinding of the DNA double helix ahead of the replication fork as the DNA is opening up; it does so by causing temporary nicks in the DNA helix and then resealing it. As synthesis proceeds, the RNA primers are replaced by DNA. The primers are removed by the exonuclease activity of DNA polymerase I, and the gaps are filled in. The nicks that remain between the newly synthesized DNA (that replaced the RNA primer) and the previously synthesized DNA are sealed by the enzyme DNA ligase that catalyzes the formation of covalent phosphodiester linkage between the 3’-OH end of one DNA fragment and the 5’ phosphate end of the other fragment, stabilizing the sugar-phosphate backbone of the DNA molecule. Termination Once the complete chromosome has been replicated, termination of DNA replication must occur. Although much is known about initiation of replication, less is known about the termination process. Following replication, the resulting complete circular genomes of prokaryotes are concatenated, meaning that the circular DNA chromosomes are interlocked and must be separated from each other. This is accomplished through the activity of bacterial topoisomerase IV, which introduces double-stranded breaks into DNA molecules, allowing them to separate from each other; the enzyme then reseals the circular chromosomes. The resolution of concatemers is an issue unique to prokaryotic DNA replication because of their circular chromosomes. Because both bacterial DNA gyrase and topoisomerase IV are distinct from their eukaryotic counterparts, these enzymes serve as targets for a class of antimicrobial drugs called quinolones . The Molecular Machinery Involved in Bacterial DNA Replication Enzyme or Factor Function DNA pol I Exonuclease activity removes RNA primer and replaces it with newly synthesized DNA DNA pol III Main enzyme that adds nucleotides in the 5’ to 3’ direction Helicase Opens the DNA helix by breaking hydrogen bonds between the nitrogenous bases Ligase Seals the gaps between the Okazaki fragments on the lagging strand to create one continuous DNA strand Primase Synthesizes RNA primers needed to start replication Single-stranded binding proteins Bind to single-stranded DNA to prevent hydrogen bonding between DNA strands, reforming double-stranded DNA Sliding clamp Helps hold DNA pol III in place when nucleotides are being added Topoisomerase II (DNA gyrase) Relaxes supercoiled chromosome to make DNA more accessible for the initiation of replication; helps relieve the stress on DNA when unwinding, by causing breaks and then resealing the DNA Topoisomerase IV Introduces single-stranded break into concatenated chromosomes to release them from each other, and then reseals the DNA Table 11.1 Check Your Understanding Which enzyme breaks the hydrogen bonds holding the two strands of DNA together so that replication can occur? Is it the lagging strand or the leading strand that is synthesized in the direction toward the opening of the replication fork? Which enzyme is responsible for removing the RNA primers in newly replicated bacterial DNA? DNA Replication in Eukaryotes Eukaryotic genomes are much more complex and larger than prokaryotic genomes and are typically composed of multiple linear chromosomes ( Table 11.2 ). The human genome , for example, has 3 billion base pairs per haploid set of chromosomes, and 6 billion base pairs are inserted during replication. There are multiple origins of replication on each eukaryotic chromosome ( Figure 11.8 ); the human genome has 30,000 to 50,000 origins of replication. The rate of replication is approximately 100 nucleotides per second—10 times slower than prokaryotic replication. The essential steps of replication in eukaryotes are the same as in prokaryotes. Before replication can start, the DNA has to be made available as a template. Eukaryotic DNA is highly supercoiled and packaged, which is facilitated by many proteins, including histone s (see Structure and Function of Cellular Genomes ). At the origin of replication , a prereplication complex composed of several proteins, including helicase , forms and recruits other enzymes involved in the initiation of replication, including topoisomerase to relax supercoiling, single-stranded binding protein, RNA primase , and DNA polymerase . Following initiation of replication, in a process similar to that found in prokaryotes, elongation is facilitated by eukaryotic DNA polymerases. The leading strand is continuously synthesized by the eukaryotic polymerase enzyme pol δ, while the lagging strand is synthesized by pol ε. A sliding clamp protein holds the DNA polymerase in place so that it does not fall off the DNA. The enzyme ribonuclease H ( RNase H ), instead of a DNA polymerase as in bacteria, removes the RNA primer, which is then replaced with DNA nucleotides. The gaps that remain are sealed by DNA ligase . Because eukaryotic chromosomes are linear, one might expect that their replication would be more straightforward. As in prokaryotes, the eukaryotic DNA polymerase can add nucleotides only in the 5’ to 3’ direction. In the leading strand, synthesis continues until it reaches either the end of the chromosome or another replication fork progressing in the opposite direction. On the lagging strand, DNA is synthesized in short stretches, each of which is initiated by a separate primer. When the replication fork reaches the end of the linear chromosome, there is no place to make a primer for the DNA fragment to be copied at the end of the chromosome. These ends thus remain unpaired and, over time, they may get progressively shorter as cells continue to divide. The ends of the linear chromosomes are known as telomere s and consist of noncoding repetitive sequences. The telomeres protect coding sequences from being lost as cells continue to divide. In humans, a six base-pair sequence, TTAGGG, is repeated 100 to 1000 times to form the telomere. The discovery of the enzyme telomerase ( Figure 11.9 ) clarified our understanding of how chromosome ends are maintained. Telomerase contains a catalytic part and a built-in RNA template. It attaches to the end of the chromosome, and complementary bases to the RNA template are added on the 3’ end of the DNA strand. Once the 3’ end of the lagging strand template is sufficiently elongated, DNA polymerase can add the nucleotides complementary to the ends of the chromosomes. In this way, the ends of the chromosomes are replicated. In humans, telomerase is typically active in germ cells and adult stem cells; it is not active in adult somatic cells and may be associated with the aging of these cells. Eukaryotic microbes including fungi and protozoans also produce telomerase to maintain chromosomal integrity. For her discovery of telomerase and its action, Elizabeth Blackburn (1948–) received the Nobel Prize for Medicine or Physiology in 2009. Comparison of Bacterial and Eukaryotic Replication Property Bacteria Eukaryotes Genome structure Single circular chromosome Multiple linear chromosomes Number of origins per chromosome Single Multiple Rate of replication 1000 nucleotides per second 100 nucleotides per second Telomerase Not present Present RNA primer removal DNA pol I RNase H Strand elongation DNA pol III pol δ, pol ε Table 11.2 Link to Learning This animation compares the process of prokaryotic and eukaryotic DNA replication. Check Your Understanding How does the origin of replication differ between eukaryotes and prokaryotes? What polymerase enzymes are responsible for DNA synthesis during eukaryotic replication? What is found at the ends of the chromosomes in eukaryotes and why? DNA Replication of Extrachromosomal Elements: Plasmids and Viruses To copy their nucleic acids, plasmids and viruses frequently use variations on the pattern of DNA replication described for prokaryote genomes. For more information on the wide range of viral replication strategies, see The Viral Life Cycle . Rolling Circle Replication Whereas many bacterial plasmids (see Unique Characteristics of Prokaryotic Cells ) replicate by a process similar to that used to copy the bacterial chromosome, other plasmids, several bacteriophages , and some viruses of eukaryotes use rolling circle replication ( Figure 11.10 ). The circular nature of plasmids and the circularization of some viral genomes on infection make this possible. Rolling circle replication begins with the enzymatic nicking of one strand of the double-stranded circular molecule at the double-stranded origin (dso) site . In bacteria, DNA polymerase III binds to the 3’-OH group of the nicked strand and begins to unidirectionally replicate the DNA using the un-nicked strand as a template, displacing the nicked strand as it does so. Completion of DNA replication at the site of the original nick results in full displacement of the nicked strand, which may then recircularize into a single-stranded DNA molecule. RNA primase then synthesizes a primer to initiate DNA replication at the single-stranded origin (sso) site of the single-stranded DNA (ssDNA) molecule, resulting in a double-stranded DNA (dsDNA) molecule identical to the other circular DNA molecule. Check Your Understanding Is there a lagging strand in rolling circle replication? Why or why not? 11.3 RNA Transcription Learning Objectives Explain how RNA is synthesized using DNA as a template Distinguish between transcription in prokaryotes and eukaryotes During the process of transcription , the information encoded within the DNA sequence of one or more genes is transcribed into a strand of RNA, also called an RNA transcript . The resulting single-stranded RNA molecule, composed of ribonucleotides containing the bases adenine (A), cytosine (C), guanine (G), and uracil (U), acts as a mobile molecular copy of the original DNA sequence. Transcription in prokaryotes and in eukaryotes requires the DNA double helix to partially unwind in the region of RNA synthesis. The unwound region is called a transcription bubble . Transcription of a particular gene always proceeds from one of the two DNA strands that acts as a template, the so-called antisense strand . The RNA product is complementary to the template strand of DNA and is almost identical to the nontemplate DNA strand, or the sense strand . The only difference is that in RNA, all of the T nucleotides are replaced with U nucleotides; during RNA synthesis, U is incorporated when there is an A in the complementary antisense strand. Transcription in Bacteria Bacteria use the same RNA polymerase to transcribe all of their genes. Like DNA polymerase, RNA polymerase adds nucleotides one by one to the 3’-OH group of the growing nucleotide chain. One critical difference in activity between DNA polymerase and RNA polymerase is the requirement for a 3’-OH onto which to add nucleotides: DNA polymerase requires such a 3’-OH group, thus necessitating a primer, whereas RNA polymerase does not. During transcription, a ribonucleotide complementary to the DNA template strand is added to the growing RNA strand and a covalent phosphodiester bond is formed by dehydration synthesis between the new nucleotide and the last one added. In E. coli , RNA polymerase comprises six polypeptide subunits, five of which compose the polymerase core enzyme responsible for adding RNA nucleotides to a growing strand. The sixth subunit is known as sigma (σ). The σ factor enables RNA polymerase to bind to a specific promoter, thus allowing for the transcription of various genes. There are various σ factors that allow for transcription of various genes. Initiation The initiation of transcription begins at a promoter , a DNA sequence onto which the transcription machinery binds and initiates transcription. The nucleotide pair in the DNA double helix that corresponds to the site from which the first 5’ RNA nucleotide is transcribed is the initiation site. Nucleotides preceding the initiation site are designated “upstream,” whereas nucleotides following the initiation site are called “downstream” nucleotides. In most cases, promoters are located just upstream of the genes they regulate. Although promoter sequences vary among bacterial genomes, a few elements are conserved. At the –10 and –35 positions within the DNA prior to the initiation site (designated +1), there are two promoter consensus sequences, or regions that are similar across all promoters and across various bacterial species. The –10 consensus sequence, called the TATA box , is TATAAT. The –35 sequence is recognized and bound by σ. Elongation The elongation in transcription phase begins when the σ subunit dissociates from the polymerase, allowing the core enzyme to synthesize RNA complementary to the DNA template in a 5’ to 3’ direction at a rate of approximately 40 nucleotides per second. As elongation proceeds, the DNA is continuously unwound ahead of the core enzyme and rewound behind it ( Figure 11.11 ). Termination Once a gene is transcribed, the bacterial polymerase must dissociate from the DNA template and liberate the newly made RNA. This is referred to as termination of transcription . The DNA template includes repeated nucleotide sequences that act as termination signals, causing RNA polymerase to stall and release from the DNA template, freeing the RNA transcript. Check Your Understanding Where does σ factor of RNA polymerase bind DNA to start transcription? What occurs to initiate the polymerization activity of RNA polymerase? Where does the signal to end transcription come from? Transcription in Eukaryotes Prokaryotes and eukaryotes perform fundamentally the same process of transcription, with a few significant differences (see Table 11.3 ). Eukaryotes use three different polymerases, RNA polymerases I, II, and III, all structurally distinct from the bacterial RNA polymerase . Each transcribes a different subset of genes. Interestingly, archaea contain a single RNA polymerase that is more closely related to eukaryotic RNA polymerase II than to its bacterial counterpart. Eukaryotic mRNAs are also usually monocistronic, meaning that they each encode only a single polypeptide, whereas prokaryotic mRNAs of bacteria and archaea are commonly polycistronic , meaning that they encode multiple polypeptides. The most important difference between prokaryotes and eukaryotes is the latter’s membrane-bound nucleus, which influences the ease of use of RNA molecules for protein synthesis. With the genes bound in a nucleus, the eukaryotic cell must transport protein-encoding RNA molecules to the cytoplasm to be translated. Protein-encoding primary transcript s, the RNA molecules directly synthesized by RNA polymerase, must undergo several processing steps to protect these RNA molecules from degradation during the time they are transferred from the nucleus to the cytoplasm and translated into a protein. For example, eukaryotic mRNAs may last for several hours, whereas the typical prokaryotic mRNA lasts no more than 5 seconds. The primary transcript (also called pre-mRNA) is first coated with RNA-stabilizing proteins to protect it from degradation while it is processed and exported out of the nucleus. The first type of processing begins while the primary transcript is still being synthesized; a special 7-methylguanosine nucleotide, called the 5’ cap , is added to the 5’ end of the growing transcript. In addition to preventing degradation, factors involved in subsequent protein synthesis recognize the cap, which helps initiate translation by ribosomes. Once elongation is complete, another processing enzyme then adds a string of approximately 200 adenine nucleotides to the 3’ end, called the poly-A tail . This modification further protects the pre-mRNA from degradation and signals to cellular factors that the transcript needs to be exported to the cytoplasm. Eukaryotic genes that encode polypeptides are composed of coding sequences called exon s ( ex -on signifies that they are ex pressed) and intervening sequences called intron s ( int -ron denotes their int ervening role). Transcribed RNA sequences corresponding to introns do not encode regions of the functional polypeptide and are removed from the pre-mRNA during processing. It is essential that all of the intron-encoded RNA sequences are completely and precisely removed from a pre-mRNA before protein synthesis so that the exon-encoded RNA sequences are properly joined together to code for a functional polypeptide. If the process errs by even a single nucleotide, the sequences of the rejoined exons would be shifted, and the resulting polypeptide would be nonfunctional. The process of removing intron-encoded RNA sequences and reconnecting those encoded by exons is called RNA splicing and is facilitated by the action of a spliceosome containing small nuclear ribonucleo proteins (snRNPs). Intron-encoded RNA sequences are removed from the pre-mRNA while it is still in the nucleus. Although they are not translated, introns appear to have various functions, including gene regulation and mRNA transport. On completion of these modifications, the mature transcript , the mRNA that encodes a polypeptide, is transported out of the nucleus, destined for the cytoplasm for translation. Introns can be spliced out differently, resulting in various exons being included or excluded from the final mRNA product. This process is known as alternative splicing . The advantage of alternative splicing is that different types of mRNA transcripts can be generated, all derived from the same DNA sequence. In recent years, it has been shown that some archaea also have the ability to splice their pre-mRNA. Comparison of Transcription in Bacteria Versus Eukaryotes Property Bacteria Eukaryotes Number of polypeptides encoded per mRNA Monocistronic or polycistronic Exclusively monocistronic Strand elongation core + σ = holoenzyme RNA polymerases I, II, or III Addition of 5’ cap No Yes Addition of 3’ poly-A tail No Yes Splicing of pre-mRNA No Yes Table 11.3 Link to Learning Visualize how mRNA splicing happens by watching the process in action in this video. See how introns are removed during RNA splicing here. Check Your Understanding In eukaryotic cells, how is the RNA transcript from a gene for a protein modified after it is transcribed? Do exons or introns contain information for protein sequences? Clinical Focus Part 2 In the emergency department, a nurse told Mark that he had made a good decision to come to the hospital because his symptoms indicated an infection that had gotten out of control. Mark’s symptoms had progressed, with the area of skin affected and the amount of swelling increasing. Within the affected area, a rash had begun, blistering and small gas pockets underneath the outermost layer of skin had formed, and some of the skin was becoming gray. Based on the putrid smell of the pus draining from one of the blisters, the rapid progression of the infection, and the visual appearance of the affected skin, the physician immediately began treatment for necrotizing fasciitis. Mark’s physician ordered a culture of the fluid draining from the blister and also ordered blood work, including a white blood cell count. Mark was admitted to the intensive care unit and began intravenous administration of a broad-spectrum antibiotic to try to minimize further spread of the infection. Despite antibiotic therapy, Mark’s condition deteriorated quickly. Mark became confused and dizzy. Within a few hours of his hospital admission, his blood pressure dropped significantly and his breathing became shallower and more rapid. Additionally, blistering increased, with the blisters intensifying in color to purplish black, and the wound itself seemed to be progressing rapidly up Mark’s leg. What are possible causative agents of Mark’s necrotizing fasciitis? What are some possible explanations for why the antibiotic treatment does not seem to be working? Jump to the next Clinical Focus box. Go back to the previous Clinical Focus box. 11.4 Protein Synthesis (Translation) Learning Objectives Describe the genetic code and explain why it is considered almost universal Explain the process of translation and the functions of the molecular machinery of translation Compare translation in eukaryotes and prokaryotes The synthesis of proteins consumes more of a cell’s energy than any other metabolic process. In turn, proteins account for more mass than any other macromolecule of living organisms. They perform virtually every function of a cell, serving as both functional (e.g., enzymes) and structural elements. The process of translation , or protein synthesis , the second part of gene expression, involves the decoding by a ribosome of an mRNA message into a polypeptide product. The Genetic Code Translation of the mRNA template converts nucleotide-based genetic information into the “language” of amino acids to create a protein product. A protein sequence consists of 20 commonly occurring amino acids . Each amino acid is defined within the mRNA by a triplet of nucleotides called a codon . The relationship between an mRNA codon and its corresponding amino acid is called the genetic code . The three-nucleotide code means that there is a total of 64 possible combinations (4 3 , with four different nucleotides possible at each of the three different positions within the codon). This number is greater than the number of amino acids and a given amino acid is encoded by more than one codon ( Figure 11.12 ). This redundancy in the genetic code is called degeneracy . Typically, whereas the first two positions in a codon are important for determining which amino acid will be incorporated into a growing polypeptide, the third position, called the wobble position , is less critical. In some cases, if the nucleotide in the third position is changed, the same amino acid is still incorporated. Whereas 61 of the 64 possible triplets code for amino acids, three of the 64 codons do not code for an amino acid; they terminate protein synthesis, releasing the polypeptide from the translation machinery. These are called stop codon s or nonsense codon s . Another codon, AUG, also has a special function. In addition to specifying the amino acid methionine, it also typically serves as the start codon to initiate translation. The reading frame , the way nucleotides in mRNA are grouped into codons, for translation is set by the AUG start codon near the 5’ end of the mRNA. Each set of three nucleotides following this start codon is a codon in the mRNA message. The genetic code is nearly universal. With a few exceptions, virtually all species use the same genetic code for protein synthesis, which is powerful evidence that all extant life on earth shares a common origin. However, unusual amino acids such as selenocysteine and pyrrolysine have been observed in archaea and bacteria. In the case of selenocysteine, the codon used is UGA (normally a stop codon). However, UGA can encode for selenocysteine using a stem-loop structure (known as the selenocysteine insertion sequence, or SECIS element), which is found at the 3’ untranslated region of the mRNA. Pyrrolysine uses a different stop codon, UAG. The incorporation of pyrrolysine requires the pylS gene and a unique transfer RNA (tRNA) with a CUA anticodon. Check Your Understanding How many bases are in each codon? What amino acid is coded for by the codon AAU? What happens when a stop codon is reached? The Protein Synthesis Machinery In addition to the mRNA template, many molecules and macromolecules contribute to the process of translation . The composition of each component varies across taxa; for instance, ribosomes may consist of different numbers of ribosomal RNAs (rRNAs) and polypeptides depending on the organism. However, the general structures and functions of the protein synthesis machinery are comparable from bacteria to human cells. Translation requires the input of an mRNA template, ribosomes, tRNAs, and various enzymatic factors. Ribosomes A ribosome is a complex macromolecule composed of catalytic rRNAs (called ribozyme s) and structural rRNA s, as well as many distinct polypeptides. Mature rRNAs make up approximately 50% of each ribosome. Prokaryotes have 70S ribosomes, whereas eukaryotes have 80S ribosomes in the cytoplasm and rough endoplasmic reticulum, and 70S ribosomes in mitochondria and chloroplasts . Ribosomes dissociate into large and small subunits when they are not synthesizing proteins and reassociate during the initiation of translation . In E. coli , the small subunit is described as 30S (which contains the 16S rRNA subunit), and the large subunit is 50S (which contains the 5S and 23S rRNA subunits), for a total of 70S (Svedberg units are not additive). Eukaryote ribosomes have a small 40S subunit (which contains the 18S rRNA subunit) and a large 60S subunit (which contains the 5S, 5.8S and 28S rRNA subunits), for a total of 80S. The small subunit is responsible for binding the mRNA template, whereas the large subunit binds tRNAs (discussed in the next subsection). Each mRNA molecule is simultaneously translated by many ribosomes, all synthesizing protein in the same direction: reading the mRNA from 5’ to 3’ and synthesizing the polypeptide from the N terminus to the C terminus. The complete structure containing an mRNA with multiple associated ribosomes is called a polyribosome (or polysome ). In both bacteria and archaea , before transcriptional termination occurs, each protein-encoding transcript is already being used to begin synthesis of numerous copies of the encoded polypeptide(s) because the processes of transcription and translation can occur concurrently, forming polyribosomes ( Figure 11.13 ). The reason why transcription and translation can occur simultaneously is because both of these processes occur in the same 5’ to 3’ direction, they both occur in the cytoplasm of the cell, and because the RNA transcript is not processed once it is transcribed. This allows a prokaryotic cell to respond to an environmental signal requiring new proteins very quickly. In contrast, in eukaryotic cells, simultaneous transcription and translation is not possible. Although polyribosomes also form in eukaryotes, they cannot do so until RNA synthesis is complete and the RNA molecule has been modified and transported out of the nucleus. Transfer RNAs Transfer RNAs (tRNAs) are structural RNA molecules and, depending on the species, many different types of tRNAs exist in the cytoplasm. Bacterial species typically have between 60 and 90 types. Serving as adaptors, each tRNA type binds to a specific codon on the mRNA template and adds the corresponding amino acid to the polypeptide chain. Therefore, tRNAs are the molecules that actually “translate” the language of RNA into the language of proteins. As the adaptor molecules of translation, it is surprising that tRNAs can fit so much specificity into such a small package. The tRNA molecule interacts with three factors: aminoacyl tRNA synthetases, ribosomes, and mRNA. Mature tRNAs take on a three-dimensional structure when complementary bases exposed in the single-stranded RNA molecule hydrogen bond with each other ( Figure 11.14 ). This shape positions the amino-acid binding site, called the CCA amino acid binding end , which is a cytosine-cytosine-adenine sequence at the 3’ end of the tRNA, and the anticodon at the other end. The anticodon is a three-nucleotide sequence that bonds with an mRNA codon through complementary base pairing. An amino acid is added to the end of a tRNA molecule through the process of tRNA “charging,” during which each tRNA molecule is linked to its correct or cognate amino acid by a group of enzymes called aminoacyl tRNA synthetase s. At least one type of aminoacyl tRNA synthetase exists for each of the 20 amino acids. During this process, the amino acid is first activated by the addition of adenosine monophosphate (AMP) and then transferred to the tRNA, making it a charged tRNA , and AMP is released. Check Your Understanding Describe the structure and composition of the prokaryotic ribosome. In what direction is the mRNA template read? Describe the structure and function of a tRNA. The Mechanism of Protein Synthesis Translation is similar in prokaryotes and eukaryotes. Here we will explore how translation occurs in E. coli , a representative prokaryote, and specify any differences between bacterial and eukaryotic translation. Initiation The initiation of protein synthesis begins with the formation of an initiation complex. In E. coli , this complex involves the small 30S ribosome, the mRNA template, three initiation factors that help the ribosome assemble correctly, guanosine triphosphate (GTP) that acts as an energy source, and a special initiator tRNA carrying N -formyl-methionine (fMet-tRNA fMet ) ( Figure 11.15 ). The initiator tRNA interacts with the start codon AUG of the mRNA and carries a formylated methionine (fMet). Because of its involvement in initiation, fMet is inserted at the beginning (N terminus) of every polypeptide chain synthesized by E. coli . In E. coli mRNA, a leader sequence upstream of the first AUG codon, called the Shine-Dalgarno sequence (also known as the ribosomal binding site AGGAGG), interacts through complementary base pairing with the rRNA molecules that compose the ribosome. This interaction anchors the 30S ribosomal subunit at the correct location on the mRNA template. At this point, the 50S ribosomal subunit then binds to the initiation complex, forming an intact ribosome. In eukaryotes, initiation complex formation is similar, with the following differences: The initiator tRNA is a different specialized tRNA carrying methionine, called Met-tRNAi Instead of binding to the mRNA at the Shine-Dalgarno sequence, the eukaryotic initiation complex recognizes the 5’ cap of the eukaryotic mRNA, then tracks along the mRNA in the 5’ to 3’ direction until the AUG start codon is recognized. At this point, the 60S subunit binds to the complex of Met-tRNAi, mRNA, and the 40S subunit. Elongation In prokaryotes and eukaryotes, the basics of elongation of translation are the same. In E. coli , the binding of the 50S ribosomal subunit to produce the intact ribosome forms three functionally important ribosomal sites: The A (aminoacyl) site binds incoming charged aminoacyl tRNAs. The P (peptidyl) site binds charged tRNAs carrying amino acids that have formed peptide bonds with the growing polypeptide chain but have not yet dissociated from their corresponding tRNA. The E (exit) site releases dissociated tRNAs so that they can be recharged with free amino acids. There is one notable exception to this assembly line of tRNAs: During initiation complex formation, bacterial fMet−tRNA fMet or eukaryotic Met-tRNAi enters the P site directly without first entering the A site, providing a free A site ready to accept the tRNA corresponding to the first codon after the AUG. Elongation proceeds with single-codon movements of the ribosome each called a translocation event. During each translocation event, the charged tRNAs enter at the A site, then shift to the P site, and then finally to the E site for removal. Ribosomal movements, or steps, are induced by conformational changes that advance the ribosome by three bases in the 3’ direction. Peptide bonds form between the amino group of the amino acid attached to the A-site tRNA and the carboxyl group of the amino acid attached to the P-site tRNA. The formation of each peptide bond is catalyzed by peptidyl transferase , an RNA-based ribozyme that is integrated into the 50S ribosomal subunit. The amino acid bound to the P-site tRNA is also linked to the growing polypeptide chain. As the ribosome steps across the mRNA, the former P-site tRNA enters the E site, detaches from the amino acid, and is expelled. Several of the steps during elongation, including binding of a charged aminoacyl tRNA to the A site and translocation, require energy derived from GTP hydrolysis, which is catalyzed by specific elongation factors. Amazingly, the E. coli translation apparatus takes only 0.05 seconds to add each amino acid, meaning that a 200 amino-acid protein can be translated in just 10 seconds. Termination The termination of translation occurs when a nonsense codon (UAA, UAG, or UGA) is encountered for which there is no complementary tRNA. On aligning with the A site, these nonsense codons are recognized by release factors in prokaryotes and eukaryotes that result in the P-site amino acid detaching from its tRNA, releasing the newly made polypeptide. The small and large ribosomal subunits dissociate from the mRNA and from each other; they are recruited almost immediately into another translation initiation complex. In summary, there are several key features that distinguish prokaryotic gene expression from that seen in eukaryotes. These are illustrated in Figure 11.16 and listed in Figure 11.17 . Protein Targeting, Folding, and Modification During and after translation, polypeptides may need to be modified before they are biologically active. Post-translational modifications include: removal of translated signal sequences—short tails of amino acids that aid in directing a protein to a specific cellular compartment proper “folding” of the polypeptide and association of multiple polypeptide subunits, often facilitated by chaperone proteins, into a distinct three-dimensional structure proteolytic processing of an inactive polypeptide to release an active protein component, and various chemical modifications (e.g., phosphorylation, methylation, or glycosylation) of individual amino acids. Check Your Understanding What are the components of the initiation complex for translation in prokaryotes? What are two differences between initiation of prokaryotic and eukaryotic translation? What occurs at each of the three active sites of the ribosome? What causes termination of translation? 11.5 Mutations Learning Objectives Compare point mutations and frameshift mutations Describe the differences between missense, nonsense, and silent mutations Describe the differences between light and dark repair Explain how different mutagens act Explain why the Ames test can be used to detect carcinogens Analyze sequences of DNA and identify examples of types of mutations A mutation is a heritable change in the DNA sequence of an organism. The resulting organism, called a mutant , may have a recognizable change in phenotype compared to the wild type , which is the phenotype most commonly observed in nature. A change in the DNA sequence is conferred to mRNA through transcription, and may lead to an altered amino acid sequence in a protein on translation. Because proteins carry out the vast majority of cellular functions, a change in amino acid sequence in a protein may lead to an altered phenotype for the cell and organism. Effects of Mutations on DNA Sequence There are several types of mutations that are classified according to how the DNA molecule is altered. One type, called a point mutation , affects a single base and most commonly occurs when one base is substituted or replaced by another. Mutations also result from the addition of one or more bases, known as an insertion , or the removal of one or more bases, known as a deletion . Check Your Understanding What type of a mutation occurs when a gene has two fewer nucleotides in its sequence? Effects of Mutations on Protein Structure and Function Point mutations may have a wide range of effects on protein function ( Figure 11.18 ). As a consequence of the degeneracy of the genetic code, a point mutation will commonly result in the same amino acid being incorporated into the resulting polypeptide despite the sequence change. This change would have no effect on the protein’s structure, and is thus called a silent mutation . A missense mutation results in a different amino acid being incorporated into the resulting polypeptide. The effect of a missense mutation depends on how chemically different the new amino acid is from the wild-type amino acid. The location of the changed amino acid within the protein also is important. For example, if the changed amino acid is part of the enzyme’s active site , then the effect of the missense mutation may be significant. Many missense mutations result in proteins that are still functional, at least to some degree. Sometimes the effects of missense mutations may be only apparent under certain environmental conditions; such missense mutations are called conditional mutation s. Rarely, a missense mutation may be beneficial. Under the right environmental conditions, this type of mutation may give the organism that harbors it a selective advantage. Yet another type of point mutation, called a nonsense mutation , converts a codon encoding an amino acid (a sense codon) into a stop codon (a nonsense codon). Nonsense mutations result in the synthesis of proteins that are shorter than the wild type and typically not functional. Deletions and insertions also cause various effects. Because codons are triplets of nucleotides, insertions or deletions in groups of three nucleotides may lead to the insertion or deletion of one or more amino acids and may not cause significant effects on the resulting protein’s functionality. However, frameshift mutation s, caused by insertions or deletions of a number of nucleotides that are not a multiple of three are extremely problematic because a shift in the reading frame results ( Figure 11.18 ). Because ribosomes read the mRNA in triplet codons, frameshift mutations can change every amino acid after the point of the mutation. The new reading frame may also include a stop codon before the end of the coding sequence. Consequently, proteins made from genes containing frameshift mutations are nearly always nonfunctional. Check Your Understanding What are the reasons a nucleotide change in a gene for a protein might not have any effect on the phenotype of that gene? Is it possible for an insertion of three nucleotides together after the fifth nucleotide in a protein-coding gene to produce a protein that is shorter than normal? How or how not? Micro Connections A Beneficial Mutation Since the first case of infection with human immunodeficiency virus (HIV) was reported in 1981, nearly 40 million people have died from HIV infection, 2 the virus that causes acquired immune deficiency syndrome (AIDS). The virus targets helper T cells that play a key role in bridging the innate and adaptive immune response, infecting and killing cells normally involved in the body’s response to infection. There is no cure for HIV infection, but many drugs have been developed to slow or block the progression of the virus. Although individuals around the world may be infected, the highest prevalence among people 15–49 years old is in sub-Saharan Africa, where nearly one person in 20 is infected, accounting for greater than 70% of the infections worldwide 3 ( Figure 11.19 ). Unfortunately, this is also a part of the world where prevention strategies and drugs to treat the infection are the most lacking. 2 World Health Organization. “ Global Health Observatory (GHO) Data, HIV/AIDS.” http://www.who.int/gho/hiv/en/. Accessed August 5, 2016. 3 World Health Organization. “ Global Health Observatory (GHO) Data, HIV/AIDS.” http://www.who.int/gho/hiv/en/. Accessed August 5, 2016. In recent years, scientific interest has been piqued by the discovery of a few individuals from northern Europe who are resistant to HIV infection. In 1998, American geneticist Stephen J. O’Brien at the National Institutes of Health (NIH) and colleagues published the results of their genetic analysis of more than 4,000 individuals. These indicated that many individuals of Eurasian descent (up to 14% in some ethnic groups) have a deletion mutation, called CCR5-delta 32, in the gene encoding CCR5. CCR5 is a coreceptor found on the surface of T cells that is necessary for many strains of the virus to enter the host cell. The mutation leads to the production of a receptor to which HIV cannot effectively bind and thus blocks viral entry. People homozygous for this mutation have greatly reduced susceptibility to HIV infection, and those who are heterozygous have some protection from infection as well. It is not clear why people of northern European descent, specifically, carry this mutation, but its prevalence seems to be highest in northern Europe and steadily decreases in populations as one moves south. Research indicates that the mutation has been present since before HIV appeared and may have been selected for in European populations as a result of exposure to the plague or smallpox. This mutation may protect individuals from plague (caused by the bacterium Yersinia pestis ) and smallpox (caused by the variola virus) because this receptor may also be involved in these diseases. The age of this mutation is a matter of debate, but estimates suggest it appeared between 1875 years to 225 years ago, and may have been spread from Northern Europe through Viking invasions. This exciting finding has led to new avenues in HIV research, including looking for drugs to block CCR5 binding to HIV in individuals who lack the mutation. Although DNA testing to determine which individuals carry the CCR5-delta 32 mutation is possible, there are documented cases of individuals homozygous for the mutation contracting HIV. For this reason, DNA testing for the mutation is not widely recommended by public health officials so as not to encourage risky behavior in those who carry the mutation. Nevertheless, inhibiting the binding of HIV to CCR5 continues to be a valid strategy for the development of drug therapies for those infected with HIV. Causes of Mutations Mistakes in the process of DNA replication can cause spontaneous mutation s to occur. The error rate of DNA polymerase is one incorrect base per billion base pairs replicated. Exposure to mutagen s can cause induced mutation s , which are various types of chemical agents or radiation ( Table 11.4 ). Exposure to a mutagen can increase the rate of mutation more than 1000-fold. Mutagens are often also carcinogen s , agents that cause cancer. However, whereas nearly all carcinogens are mutagenic, not all mutagens are necessarily carcinogens. Chemical Mutagens Various types of chemical mutagens interact directly with DNA either by acting as nucleoside analogs or by modifying nucleotide bases. Chemicals called nucleoside analog s are structurally similar to normal nucleotide bases and can be incorporated into DNA during replication ( Figure 11.20 ). These base analogs induce mutations because they often have different base-pairing rules than the bases they replace. Other chemical mutagens can modify normal DNA bases, resulting in different base-pairing rules. For example, nitrous acid deaminates cytosine, converting it to uracil. Uracil then pairs with adenine in a subsequent round of replication, resulting in the conversion of a GC base pair to an AT base pair. Nitrous acid also deaminates adenine to hypoxanthine, which base pairs with cytosine instead of thymine, resulting in the conversion of a TA base pair to a CG base pair. Chemical mutagens known as intercalating agent s work differently. These molecules slide between the stacked nitrogenous bases of the DNA double helix, distorting the molecule and creating atypical spacing between nucleotide base pairs ( Figure 11.21 ). As a result, during DNA replication, DNA polymerase may either skip replicating several nucleotides (creating a deletion ) or insert extra nucleotides (creating an insertion ). Either outcome may lead to a frameshift mutation . Combustion products like polycyclic aromatic hydrocarbons are particularly dangerous intercalating agents that can lead to mutation-caused cancers. The intercalating agents ethidium bromide and acridine orange are commonly used in the laboratory to stain DNA for visualization and are potential mutagens. Radiation Exposure to either ionizing or nonionizing radiation can each induce mutations in DNA, although by different mechanisms. Strong ionizing radiation like X-rays and gamma rays can cause single- and double-stranded breaks in the DNA backbone through the formation of hydroxyl radicals on radiation exposure ( Figure 11.22 ). Ionizing radiation can also modify bases; for example, the deamination of cytosine to uracil, analogous to the action of nitrous acid. 4 Ionizing radiation exposure is used to kill microbes to sterilize medical devices and foods, because of its dramatic nonspecific effect in damaging DNA, proteins, and other cellular components (see Using Physical Methods to Control Microorganisms ). 4 K.R. Tindall et al. “Changes in DNA Base Sequence Induced by Gamma-Ray Mutagenesis of Lambda Phage and Prophage.” Genetics 118 no. 4 (1988):551–560. Nonionizing radiation, like ultraviolet light, is not energetic enough to initiate these types of chemical changes. However, nonionizing radiation can induce dimer formation between two adjacent pyrimidine bases, commonly two thymines, within a nucleotide strand. During thymine dimer formation, the two adjacent thymines become covalently linked and, if left unrepaired, both DNA replication and transcription are stalled at this point. DNA polymerase may proceed and replicate the dimer incorrectly, potentially leading to frameshift or point mutations. A Summary of Mutagenic Agents Mutagenic Agents Mode of Action Effect on DNA Resulting Type of Mutation Nucleoside analogs 2-aminopurine Is inserted in place of A but base pairs with C Converts AT to GC base pair Point 5-bromouracil Is inserted in place of T but base pairs with G Converts AT to GC base pair Point Nucleotide-modifying agent Nitrous oxide Deaminates C to U Converts GC to AT base pair Point Intercalating agents Acridine orange, ethidium bromide, polycyclic aromatic hydrocarbons Distorts double helix, creates unusual spacing between nucleotides Introduces small deletions and insertions Frameshift Ionizing radiation X-rays, γ-rays Forms hydroxyl radicals Causes single- and double-strand DNA breaks Repair mechanisms may introduce mutations X-rays, γ-rays Modifies bases (e.g., deaminating C to U) Converts GC to AT base pair Point Nonionizing radiation Ultraviolet Forms pyrimidine (usually thymine) dimers Causes DNA replication errors Frameshift or point Table 11.4 Check Your Understanding How does a base analog introduce a mutation? How does an intercalating agent introduce a mutation? What type of mutagen causes thymine dimers? DNA Repair The process of DNA replication is highly accurate, but mistakes can occur spontaneously or be induced by mutagens. Uncorrected mistakes can lead to serious consequences for the phenotype. Cells have developed several repair mechanisms to minimize the number of mutations that persist. Proofreading Most of the mistakes introduced during DNA replication are promptly corrected by most DNA polymerase s through a function called proofreading. In proofreading , the DNA polymerase reads the newly added base, ensuring that it is complementary to the corresponding base in the template strand before adding the next one. If an incorrect base has been added, the enzyme makes a cut to release the wrong nucleotide and a new base is added. Mismatch Repair Some errors introduced during replication are corrected shortly after the replication machinery has moved. This mechanism is called mismatch repair . The enzymes involved in this mechanism recognize the incorrectly added nucleotide, excise it, and replace it with the correct base. One example is the methyl-directed mismatch repair in E. coli . The DNA is hemimethylated. This means that the parental strand is methylated while the newly synthesized daughter strand is not. It takes several minutes before the new strand is methylated. Proteins MutS, MutL, and MutH bind to the hemimethylated site where the incorrect nucleotide is found. MutH cuts the nonmethylated strand (the new strand). An exonuclease removes a portion of the strand (including the incorrect nucleotide). The gap formed is then filled in by DNA pol III and ligase. Repair of Thymine Dimers Because the production of thymine dimer s is common (many organisms cannot avoid ultraviolet light), mechanisms have evolved to repair these lesions. In nucleotide excision repair (also called dark repair), enzymes remove the pyrimidine dimer and replace it with the correct nucleotides ( Figure 11.23 ). In E. coli , the DNA is scanned by an enzyme complex. If a distortion in the double helix is found that was introduced by the pyrimidine dimer, the enzyme complex cuts the sugar-phosphate backbone several bases upstream and downstream of the dimer, and the segment of DNA between these two cuts is then enzymatically removed. DNA pol I replaces the missing nucleotides with the correct ones and DNA ligase seals the gap in the sugar-phosphate backbone. The direct repair (also called light repair) of thymine dimers occurs through the process of photoreactivation in the presence of visible light. An enzyme called photolyase recognizes the distortion in the DNA helix caused by the thymine dimer and binds to the dimer. Then, in the presence of visible light, the photolyase enzyme changes conformation and breaks apart the thymine dimer, allowing the thymines to again correctly base pair with the adenines on the complementary strand. Photoreactivation appears to be present in all organisms, with the exception of placental mammals, including humans. Photoreactivation is particularly important for organisms chronically exposed to ultraviolet radiation , like plants, photosynthetic bacteria, algae, and corals, to prevent the accumulation of mutations caused by thymine dimer formation. Check Your Understanding During mismatch repair, how does the enzyme recognize which is the new and which is the old strand? What type of mutation does photolyase repair? Identifying Bacterial Mutants One common technique used to identify bacterial mutants is called replica plating . This technique is used to detect nutritional mutants, called auxotroph s, which have a mutation in a gene encoding an enzyme in the biosynthesis pathway of a specific nutrient, such as an amino acid. As a result, whereas wild-type cells retain the ability to grow normally on a medium lacking the specific nutrient, auxotrophs are unable to grow on such a medium. During replica plating ( Figure 11.24 ), a population of bacterial cells is mutagenized and then plated as individual cells on a complex nutritionally complete plate and allowed to grow into colonies. Cells from these colonies are removed from this master plate, often using sterile velvet. This velvet, containing cells, is then pressed in the same orientation onto plates of various media. At least one plate should also be nutritionally complete to ensure that cells are being properly transferred between the plates. The other plates lack specific nutrients, allowing the researcher to discover various auxotrophic mutants unable to produce specific nutrients. Cells from the corresponding colony on the nutritionally complete plate can be used to recover the mutant for further study. Check Your Understanding Why are cells plated on a nutritionally complete plate in addition to nutrient-deficient plates when looking for a mutant? The Ames Test The Ames test , developed by Bruce Ames (1928–) in the 1970s, is a method that uses bacteria for rapid, inexpensive screening of the carcinogenic potential of new chemical compounds. The test measures the mutation rate associated with exposure to the compound, which, if elevated, may indicate that exposure to this compound is associated with greater cancer risk. The Ames test uses as the test organism a strain of Salmonella typhimurium that is a histidine auxotroph, unable to synthesize its own histidine because of a mutation in an essential gene required for its synthesis. After exposure to a potential mutagen, these bacteria are plated onto a medium lacking histidine, and the number of mutants regaining the ability to synthesize histidine is recorded and compared with the number of such mutants that arise in the absence of the potential mutagen ( Figure 11.25 ). Chemicals that are more mutagenic will bring about more mutants with restored histidine synthesis in the Ames test. Because many chemicals are not directly mutagenic but are metabolized to mutagenic forms by liver enzymes, rat liver extract is commonly included at the start of this experiment to mimic liver metabolism. After the Ames test is conducted, compounds identified as mutagenic are further tested for their potential carcinogenic properties by using other models, including animal models like mice and rats. Check Your Understanding What mutation is used as an indicator of mutation rate in the Ames test? Why can the Ames test work as a test for carcinogenicity? 11.6 How Asexual Prokaryotes Achieve Genetic Diversity Learning Objectives Compare the processes of transformation, transduction, and conjugation Explain how asexual gene transfer results in prokaryotic genetic diversity Explain the structure and consequences for bacterial genetic diversity of transposons Typically, when we consider genetic transfer, we think of vertical gene transfer , the transmission of genetic information from generation to generation. Vertical gene transfer is by far the main mode of transmission of genetic information in all cells. In sexually reproducing organisms, crossing-over events and independent assortment of individual chromosomes during meiosis contribute to genetic diversity in the population. Genetic diversity is also introduced during sexual reproduction , when the genetic information from two parents, each with different complements of genetic information, are combined, producing new combinations of parental genotypes in the diploid offspring. The occurrence of mutations also contributes to genetic diversity in a population. Genetic diversity of offspring is useful in changing or inconsistent environments and may be one reason for the evolutionary success of sexual reproduction. When prokaryotes and eukaryotes reproduce asexually, they transfer a nearly identical copy of their genetic material to their offspring through vertical gene transfer. Although asexual reproduction produces more offspring more quickly, any benefits of diversity among those offspring are lost. How then do organisms whose dominant reproductive mode is asexual create genetic diversity? In prokaryotes, horizontal gene transfer (HGT) , the introduction of genetic material from one organism to another organism within the same generation, is an important way to introduce genetic diversity. HGT allows even distantly related species to share genes, influencing their phenotypes. It is thought that HGT is more prevalent in prokaryotes but that only a small fraction of the prokaryotic genome may be transferred by this type of transfer at any one time. As the phenomenon is investigated more thoroughly, it may be revealed to be even more common. Many scientists believe that HGT and mutation are significant sources of genetic variation, the raw material for the process of natural selection, in prokaryotes. Although HGT is more common among evolutionarily related organisms, it may occur between any two species that live together in a natural community. HGT in prokaryotes is known to occur by the three primary mechanisms that are illustrated in Figure 11.26 : Transformation: naked DNA is taken up from the environment Transduction: genes are transferred between cells in a virus (see The Viral Life Cycle ) Conjugation: use of a hollow tube called a conjugation pilus to transfer genes between cells Check Your Understanding What are three ways sexual reproduction introduces genetic variation into offspring? What is a benefit of asexual reproduction? What are the three mechanisms of horizontal gene transfer in prokaryotes? Transformation Frederick Griffith was the first to demonstrate the process of transformation . In 1928, he showed that live, nonpathogenic Streptococcus pneumoniae bacteria could be transformed into pathogenic bacteria through exposure to a heat-killed pathogenic strain. He concluded that some sort of agent, which he called the “transforming principle,” had been passed from the dead pathogenic bacteria to the live, nonpathogenic bacteria. In 1944, Oswald Avery (1877–1955), Colin MacLeod (1909–1972), and Maclyn McCarty (1911–2005) demonstrated that the transforming principle was DNA (see Using Microorganisms to Discover the Secrets of Life ). In transformation , the prokaryote takes up naked DNA found in its environment and that is derived from other cells that have lysed on death and released their contents, including their genome, into the environment. Many bacteria are naturally competent, meaning that they actively bind to environmental DNA, transport it across their cell envelopes into their cytoplasm, and make it single stranded. Typically, double-stranded foreign DNA within cells is destroyed by nucleases as a defense against viral infection. However, these nucleases are usually ineffective against single-stranded DNA, so this single-stranded DNA within the cell has the opportunity to recombine into the bacterial genome. A molecule of DNA that contains fragments of DNA from different organisms is called recombinant DNA . (Recombinant DNA will be discussed in more detail in Microbes and the Tools of Genetic Engineering .) If the bacterium incorporates the new DNA into its own genome through recombination, the bacterial cell may gain new phenotypic properties. For example, if a nonpathogenic bacterium takes up DNA for a toxin gene from a pathogen and then incorporates it into its chromosome, it, too, may become pathogenic. Plasmid DNA may also be taken up by competent bacteria and confer new properties to the cell. Overall, transformation in nature is a relatively inefficient process because environmental DNA levels are low because of the activity of nucleases that are also released during cellular lysis. Additionally, genetic recombination is inefficient at incorporating new DNA sequences into the genome. In nature, bacterial transformation is an important mechanism for the acquisition of genetic elements encoding virulence factor s and antibiotic resistance . Genes encoding resistance to antimicrobial compounds have been shown to be widespread in nature, even in environments not influenced by humans. These genes, which allow microbes living in mixed communities to compete for limited resources, can be transferred within a population by transformation, as well as by the other processes of HGT. In the laboratory, we can exploit the natural process of bacterial transformation for genetic engineering to make a wide variety of medicinal products, as discussed in Microbes and the Tools of Genetic Engineering . Check Your Understanding Why does a bacterial cell make environmental DNA brought into the cell into a single-stranded form? Transduction Viruses that infect bacteria ( bacteriophages ) may also move short pieces of chromosomal DNA from one bacterium to another in a process called transduction (see Figure 6.9 ). Recall that in generalized transduction , any piece of chromosomal DNA may be transferred to a new host cell by accidental packaging of chromosomal DNA into a phage head during phage assembly. By contrast, specialized transduction results from the imprecise excision of a lysogenic prophage from the bacterial chromosome such that it carries with it a piece of the bacterial chromosome from either side of the phage’s integration site to a new host cell. As a result, the host may acquire new properties. This process is called lysogenic conversion. Of medical significance, a lysogenic phage may carry with it a virulence gene to its new host. Once inserted into the new host’s chromosome, the new host may gain pathogenicity. Several pathogenic bacteria, including Corynebacterium diphtheriae (the causative agent of diphtheria) and Clostridium botulinum (the causative agent of botulism), are virulent because of the introduction of toxin-encoding genes by lysogenic bacteriophages, affirming the clinical relevance of transduction in the exchange of genes involved in infectious disease. Archaea have their own viruses that translocate genetic material from one individual to another. Check Your Understanding What is the agent of transduction of prokaryotic cells? In specialized transduction, where does the transducing piece of DNA come from? Case in Point The Clinical Consequences of Transduction Paul, a 23-year-old relief worker from Atlanta, traveled to Haiti in 2011 to provide aid following the 2010 earthquake. After working there for several weeks, he suddenly began experiencing abdominal distress, including severe cramping, nausea, vomiting, and watery diarrhea. He also began to experience intense muscle cramping. At a local clinic, the physician suspected that Paul’s symptoms were caused by cholera because there had been a cholera outbreak after the earthquake. Because cholera is transmitted by the fecal-oral route, breaches in sanitation infrastructure, such as often occur following natural disasters, may precipitate outbreaks. The physician confirmed the presumptive diagnosis using a cholera dipstick test. He then prescribed Paul a single dose of doxycycline, as well as oral rehydration salts, instructing him to drink significant amounts of clean water. Cholera is caused by the gram-negative curved rod Vibrio cholerae ( Figure 11.27 ). Its symptoms largely result from the production of the cholera toxin (CT), which ultimately activates a chloride transporter to pump chloride ions out of the epithelial cells into the gut lumen. Water then follows the chloride ions, causing the prolific watery diarrhea characteristic of cholera. The gene encoding the cholera toxin is incorporated into the bacterial chromosome of V . cholerae through infection of the bacterium with the lysogenic filamentous CTX phage, which carries the CT gene and introduces it into the chromosome on integration of the prophage. Thus, pathogenic strains of V. cholerae result from horizontal gene transfer by specialized transduction. Why are outbreaks of cholera more common as a result of a natural disaster? Why is muscle cramping a common symptom of cholera? Why is treatment with oral rehydration salts so important for the treatment of cholera? In areas stricken by cholera, what are some strategies that people could use to prevent disease transmission? Conjugation In conjugation , DNA is directly transferred from one prokaryote to another by means of a conjugation pilus , which brings the organisms into contact with one another. In E. coli , the genes encoding the ability to conjugate are located on a bacterial plasmid called the F plasmid , also known as the fertility factor , and the conjugation pilus is called the F pilus . The F-plasmid genes encode both the proteins composing the F pilus and those involved in rolling circle replication of the plasmid. Cells containing the F plasmid, capable of forming an F pilus, are called F + cell s or donor cell s , and those lacking an F plasmid are called F − cell s or recipient cell s . Conjugation of the F Plasmid During typical conjugation in E. coli , the F pilus of an F + cell comes into contact with an F – cell and retracts, bringing the two cell envelopes into contact ( Figure 11.28 ). Then a cytoplasmic bridge forms between the two cells at the site of the conjugation pilus. As rolling circle replication of the F plasmid occurs in the F + cell, a single-stranded copy of the F plasmid is transferred through the cytoplasmic bridge to the F − cell, which then synthesizes the complementary strand, making it double stranded. The F − cell now becomes an F + cell capable of making its own conjugation pilus. Eventually, in a mixed bacterial population containing both F + and F − cells, all cells will become F + cells. Genes on the E. coli F plasmid also encode proteins preventing conjugation between F + cells. Conjugation of F’ and Hfr Cells Although typical conjugation in E. coli results in the transfer of the F-plasmid DNA only, conjugation may also transfer chromosomal DNA. This is because the F plasmid occasionally integrates into the bacterial chromosome through recombination between the plasmid and the chromosome, forming an Hfr cell ( Figure 11.29 ). “Hfr” refers to the high frequency of recombination seen when recipient F − cells receive genetic information from Hfr cells through conjugation. Similar to the imprecise excision of a prophage during specialized transduction , the integrated F plasmid may also be imprecisely excised from the chromosome, producing an F’ plasmid that carries with it some chromosomal DNA adjacent to the integration site. On conjugation, this DNA is introduced to the recipient cell and may be either maintained as part of the F’ plasmid or be recombined into the recipient cell’s bacterial chromosome. Hfr cells may also treat the bacterial chromosome like an enormous F plasmid and attempt to transfer a copy of it to a recipient F − cell. Because the bacterial chromosome is so large, transfer of the entire chromosome takes a long time ( Figure 11.30 ). However, contact between bacterial cells during conjugation is transient, so it is unusual for the entire chromosome to be transferred. Host chromosomal DNA near the integration site of the F plasmid, displaced by the unidirectional process of rolling circle replication, is more likely to be transferred and recombined into a recipient cell’s chromosome than host genes farther away. Thus, the relative location of bacterial genes on the Hfr cell’s genome can be mapped based on when they are transferred through conjugation. As a result, prior to the age of widespread bacterial genome sequencing, distances on prokaryotic genome maps were often measured in minutes. Consequences and Applications of Conjugation Plasmids are an important type of extrachromosomal DNA element in bacteria and, in those cells that harbor them, are considered to be part of the bacterial genome. From a clinical perspective, plasmid s often code for genes involved in virulence. For example, genes encoding proteins that make a bacterial cell resistant to a particular antibiotic are encoded on R plasmids . R plasmids, in addition to their genes for antimicrobial resistance, contain genes that control conjugation and transfer of the plasmid. R plasmids are able to transfer between cells of the same species and between cells of different species. Single R plasmids commonly contain multiple genes conferring resistance to multiple antibiotics. Genes required for the production of various toxins and molecules important for colonization during infection may also be found encoded on plasmids. For example, verotoxin-producing strains of E. coli ( VTEC ) appear to have acquired the genes encoding the Shiga toxin from its gram-negative relative Shigella dysenteriae through the acquisition of a large plasmid encoding this toxin. VTEC causes severe diarrheal disease that may result in hemolytic uremic syndrome (HUS), which may be lead to kidney failure and death. In nonclinical settings, bacterial genes that encode metabolic enzymes needed to degrade specialized atypical compounds like polycyclic aromatic hydrocarbons (PAHs) are also frequently encoded on plasmids. Additionally, certain plasmids have the ability to move from bacterial cells to other cell types, like those of plants and animals, through mechanisms distinct from conjugation. Such mechanisms and their use in genetic engineering are covered in Modern Applications of Microbial Genetics . Link to Learning Click through this animation to learn more about the process of conjugation. Check Your Understanding What type of replication occurs during conjugation? What occurs to produce an Hfr E. coli cell? What types of traits are encoded on plasmids? Transposition Genetic elements called transposons (transposable elements), or “ jumping genes ,” are molecules of DNA that include special inverted repeat sequences at their ends and a gene encoding the enzyme transposase ( Figure 11.31 ). Transposons allow the entire sequence to independently excise from one location in a DNA molecule and integrate into the DNA elsewhere through a process called transposition . Transposons were originally discovered in maize (corn) by American geneticist Barbara McClintock (1902–1992) in the 1940s. Transposons have since been found in all types of organisms, both prokaryotes and eukaryotes. Thus, unlike the three previous mechanisms discussed, transposition is not prokaryote-specific. Most transposons are nonreplicative, meaning they move in a “cut-and-paste” fashion. Some may be replicative, however, retaining their location in the DNA while making a copy to be inserted elsewhere (“copy and paste”). Because transposons can move within a DNA molecule, from one DNA molecule to another, or even from one cell to another, they have the ability to introduce genetic diversity. Movement within the same DNA molecule can alter phenotype by inactivating or activating a gene. Transposons may carry with them additional genes, moving these genes from one location to another with them. For example, bacterial transposons can relocate antibiotic resistance genes, moving them from chromosomes to plasmids. This mechanism has been shown to be responsible for the colocalization of multiple antibiotic resistance genes on a single R plasmid in Shigella strains causing bacterial dysentery. Such an R plasmid can then be easily transferred among a bacterial population through the process of conjugation. Check Your Understanding What are two ways a transposon can affect the phenotype of a cell it moves to? Table 11.5 summarizes the processes discussed in this section. Summary of Mechanisms of Genetic Diversity in Prokaryotes Term Definition Conjugation Transfer of DNA through direct contact using a conjugation pilus Transduction Mechanism of horizontal gene transfer in bacteria in which genes are transferred through viral infection Transformation Mechanism of horizontal gene transfer in which naked environmental DNA is taken up by a bacterial cell Transposition Process whereby DNA independently excises from one location in a DNA molecule and integrates elsewhere Table 11.5 Clinical Focus Part 3 Despite continued antibiotic treatment, Mark’s infection continued to progress rapidly. The infected region continued to expand, and he had to be put on a ventilator to help him breathe. Mark’s physician ordered surgical removal of the infected tissue. Following an initial surgery, Mark’s wound was monitored daily to ensure that the infection did not return, but it continued to spread. After two additional rounds of surgery, the infection finally seemed to be contained. A few days later, Mark was removed from the ventilator and was able to breathe on his own. However, he had lost a great deal of skin and soft tissue on his lower leg. Why does the removal of infected tissue stem the infection? What are some likely complications of this method of treatment? Jump to the next Clinical Focus box. Go back to the previous Clinical Focus box. 11.7 Gene Regulation: Operon Theory Learning Objectives Compare inducible operons and repressible operons Describe why regulation of operons is important Each nucleated cell in a multicellular organism contains copies of the same DNA. Similarly, all cells in two pure bacterial cultures inoculated from the same starting colony contain the same DNA, with the exception of changes that arise from spontaneous mutations. If each cell in a multicellular organism has the same DNA, then how is it that cells in different parts of the organism’s body exhibit different characteristics? Similarly, how is it that the same bacterial cells within two pure cultures exposed to different environmental conditions can exhibit different phenotypes? In both cases, each genetically identical cell does not turn on, or express, the same set of genes. Only a subset of proteins in a cell at a given time is expressed. Genomic DNA contains both structural gene s, which encode products that serve as cellular structures or enzymes, and regulatory gene s, which encode products that regulate gene expression. The expression of a gene is a highly regulated process. Whereas regulating gene expression in multicellular organisms allows for cellular differentiation, in single-celled organisms like prokaryotes, it primarily ensures that a cell’s resources are not wasted making proteins that the cell does not need at that time. Elucidating the mechanisms controlling gene expression is important to the understanding of human health. Malfunctions in this process in humans lead to the development of cancer and other diseases. Understanding the interaction between the gene expression of a pathogen and that of its human host is important for the understanding of a particular infectious disease. Gene regulation involves a complex web of interactions within a given cell among signals from the cell’s environment, signaling molecules within the cell, and the cell’s DNA. These interactions lead to the expression of some genes and the suppression of others, depending on circumstances. Prokaryotes and eukaryotes share some similarities in their mechanisms to regulate gene expression; however, gene expression in eukaryotes is more complicated because of the temporal and spatial separation between the processes of transcription and translation. Thus, although most regulation of gene expression occurs through transcriptional control in prokaryotes, regulation of gene expression in eukaryotes occurs at the transcriptional level and post-transcriptionally (after the primary transcript has been made). Prokaryotic Gene Regulation In bacteria and archaea , structural proteins with related functions are usually encoded together within the genome in a block called an operon and are transcribed together under the control of a single promoter , resulting in the formation of a polycistronic transcript ( Figure 11.32 ). In this way, regulation of the transcription of all of the structural genes encoding the enzymes that catalyze the many steps in a single biochemical pathway can be controlled simultaneously, because they will either all be needed at the same time, or none will be needed. For example, in E. coli , all of the structural genes that encode enzymes needed to use lactose as an energy source lie next to each other in the lactose (or lac ) operon under the control of a single promoter, the lac promoter. French scientists François Jacob (1920–2013) and Jacques Monod at the Pasteur Institute were the first to show the organization of bacterial genes into operons, through their studies on the lac operon of E. coli . For this work, they won the Nobel Prize in Physiology or Medicine in 1965. Although eukaryotic genes are not organized into operons, prokaryotic operons are excellent models for learning about gene regulation generally. There are some gene clusters in eukaryotes that function similar to operons. Many of the principles can be applied to eukaryotic systems and contribute to our understanding of changes in gene expression in eukaryotes that can result pathological changes such as cancer. Each operon includes DNA sequences that influence its own transcription; these are located in a region called the regulatory region. The regulatory region includes the promoter and the region surrounding the promoter, to which transcription factors , proteins encoded by regulatory genes, can bind. Transcription factors influence the binding of RNA polymerase to the promoter and allow its progression to transcribe structural genes. A repressor is a transcription factor that suppresses transcription of a gene in response to an external stimulus by binding to a DNA sequence within the regulatory region called the operator , which is located between the RNA polymerase binding site of the promoter and the transcriptional start site of the first structural gene. Repressor binding physically blocks RNA polymerase from transcribing structural genes. Conversely, an activator is a transcription factor that increases the transcription of a gene in response to an external stimulus by facilitating RNA polymerase binding to the promoter. An inducer , a third type of regulatory molecule, is a small molecule that either activates or represses transcription by interacting with a repressor or an activator. In prokaryotes, there are examples of operons whose gene products are required rather consistently and whose expression, therefore, is unregulated. Such operons are constitutively expressed , meaning they are transcribed and translated continuously to provide the cell with constant intermediate levels of the protein products. Such genes encode enzymes involved in housekeeping functions required for cellular maintenance, including DNA replication, repair, and expression, as well as enzymes involved in core metabolism. In contrast, there are other prokaryotic operons that are expressed only when needed and are regulated by repressors, activators, and inducers. Check Your Understanding What are the parts in the DNA sequence of an operon? What types of regulatory molecules are there? Regulation by Repression Prokaryotic operons are commonly controlled by the binding of repressors to operator regions, thereby preventing the transcription of the structural genes. Such operons are classified as either repressible operon s or inducible operons. Repressible operons, like the tryptophan ( trp ) operon, typically contain genes encoding enzymes required for a biosynthetic pathway. As long as the product of the pathway, like tryptophan, continues to be required by the cell, a repressible operon will continue to be expressed. However, when the product of the biosynthetic pathway begins to accumulate in the cell, removing the need for the cell to continue to make more, the expression of the operon is repressed. Conversely, inducible operon s , like the lac operon of E. coli , often contain genes encoding enzymes in a pathway involved in the metabolism of a specific substrate like lactose. These enzymes are only required when that substrate is available, thus expression of the operons is typically induced only in the presence of the substrate. The trp Operon: A Repressible Operon E. coli can synthesize tryptophan using enzymes that are encoded by five structural genes located next to each other in the trp operon ( Figure 11.33 ). When environmental tryptophan is low, the operon is turned on. This means that transcription is initiated, the genes are expressed, and tryptophan is synthesized. However, if tryptophan is present in the environment, the trp operon is turned off. Transcription does not occur and tryptophan is not synthesized. When tryptophan is not present in the cell, the repressor by itself does not bind to the operator; therefore, the operon is active and tryptophan is synthesized. However, when tryptophan accumulates in the cell, two tryptophan molecules bind to the trp repressor molecule, which changes its shape, allowing it to bind to the trp operator. This binding of the active form of the trp repressor to the operator blocks RNA polymerase from transcribing the structural genes, stopping expression of the operon. Thus, the actual product of the biosynthetic pathway controlled by the operon regulates the expression of the operon. Link to Learning Watch this video to learn more about the trp operon. The lac Operon: An Inducible Operon The lac operon is an example of an inducible operon that is also subject to activation in the absence of glucose ( Figure 11.34 ). The lac operon encodes three structural genes necessary to acquire and process the disaccharide lactose from the environment, breaking it down into the simple sugars glucose and galactose. For the lac operon to be expressed, lactose must be present. This makes sense for the cell because it would be energetically wasteful to create the enzymes to process lactose if lactose was not available. In the absence of lactose, the lac repressor is bound to the operator region of the lac operon, physically preventing RNA polymerase from transcribing the structural genes. However, when lactose is present, the lactose inside the cell is converted to allolactose. Allolactose serves as an inducer molecule, binding to the repressor and changing its shape so that it is no longer able to bind to the operator DNA. Removal of the repressor in the presence of lactose allows RNA polymerase to move through the operator region and begin transcription of the lac structural genes. The lac Operon: Activation by Catabolite Activator Protein Bacteria typically have the ability to use a variety of substrates as carbon sources. However, because glucose is usually preferable to other substrates, bacteria have mechanisms to ensure that alternative substrates are only used when glucose has been depleted. Additionally, bacteria have mechanisms to ensure that the genes encoding enzymes for using alternative substrates are expressed only when the alternative substrate is available. In the 1940s, Jacques Monod was the first to demonstrate the preference for certain substrates over others through his studies of E. coli ’s growth when cultured in the presence of two different substrates simultaneously. Such studies generated diauxic growth curves, like the one shown in Figure 11.35 . Although the preferred substrate glucose is used first, E. coli grows quickly and the enzymes for lactose metabolism are absent. However, once glucose levels are depleted, growth rates slow, inducing the expression of the enzymes needed for the metabolism of the second substrate, lactose. Notice how the growth rate in lactose is slower, as indicated by the lower steepness of the growth curve. The ability to switch from glucose use to another substrate like lactose is a consequence of the activity of an enzyme called Enzyme IIA (EIIA). When glucose levels drop, cells produce less ATP from catabolism (see Catabolism of Carbohydrates ), and EIIA becomes phosphorylated. Phosphorylated EIIA activates adenylyl cyclase, an enzyme that converts some of the remaining ATP to cyclic AMP (cAMP) , a cyclic derivative of AMP and important signaling molecule involved in glucose and energy metabolism in E. coli . As a result, cAMP levels begin to rise in the cell ( Figure 11.36 ). The lac operon also plays a role in this switch from using glucose to using lactose. When glucose is scarce, the accumulating cAMP caused by increased adenylyl cyclase activity binds to catabolite activator protein (CAP) , also known as cAMP receptor protein (CRP). The complex binds to the promoter region of the lac operon ( Figure 11.37 ). In the regulatory regions of these operons, a CAP binding site is located upstream of the RNA polymerase binding site in the promoter. Binding of the CAP-cAMP complex to this site increases the binding ability of RNA polymerase to the promoter region to initiate the transcription of the structural genes. Thus, in the case of the lac operon, for transcription to occur, lactose must be present (removing the lac repressor protein) and glucose levels must be depleted (allowing binding of an activating protein). When glucose levels are high, there is catabolite repression of operons encoding enzymes for the metabolism of alternative substrates. Because of low cAMP levels under these conditions, there is an insufficient amount of the CAP-cAMP complex to activate transcription of these operons. See Table 11.6 for a summary of the regulation of the lac operon. Conditions Affecting Transcription of the lac Operon Glucose CAP binds Lactose Repressor binds Transcription + – – + No + – + – Some – + – + No – + + – Yes Table 11.6 Link to Learning Watch an animated tutorial about the workings of lac operon here. Check Your Understanding What affects the binding of the trp operon repressor to the operator? How and when is the behavior of the lac repressor protein altered? In addition to being repressible, how else is the lac operon regulated? Global Responses of Prokaryotes In prokaryotes, there are also several higher levels of gene regulation that have the ability to control the transcription of many related operons simultaneously in response to an environmental signal. A group of operons all controlled simultaneously is called a regulon . Alarmones When sensing impending stress, prokaryotes alter the expression of a wide variety of operon s to respond in coordination. They do this through the production of alarmones , which are small intracellular nucleotide derivatives. Alarmones change which genes are expressed and stimulate the expression of specific stress-response genes. The use of alarmones to alter gene expression in response to stress appears to be important in pathogenic bacteria. On encountering host defense mechanisms and other harsh conditions during infection, many operons encoding virulence genes are upregulated in response to alarmone signaling. Knowledge of these responses is key to being able to fully understand the infection process of many pathogens and to the development of therapies to counter this process. Alternate σ Factors Since the σ subunit of bacterial RNA polymerase confers specificity as to which promoters should be transcribed, altering the σ factor used is another way for bacteria to quickly and globally change what regulons are transcribed at a given time. The σ factor recognizes sequences within a bacterial promoter , so different σ factors will each recognize slightly different promoter sequences. In this way, when the cell senses specific environmental conditions, it may respond by changing which σ factor it expresses, degrading the old one and producing a new one to transcribe the operons encoding genes whose products will be useful under the new environmental condition. For example, in sporulating bacteria of the genera Bacillus and Clostridium (which include many pathogens), a group of σ factors controls the expression of the many genes needed for sporulation in response to sporulation-stimulating signals. Check Your Understanding What is the name given to a collection of operons that can be regulated as a group? What type of stimulus would trigger the transcription of a different σ factor? Additional Methods of Regulation in Bacteria: Attenuation and Riboswitches Although most gene expression is regulated at the level of transcription initiation in prokaryotes, there are also mechanisms to control both the completion of transcription as well as translation concurrently. Since their discovery, these mechanisms have been shown to control the completion of transcription and translation of many prokaryotic operons. Because these mechanisms link the regulation of transcription and translation directly, they are specific to prokaryotes, because these processes are physically separated in eukaryotes. One such regulatory system is attenuation , whereby secondary stem-loop structure s formed within the 5’ end of an mRNA being transcribed determine if transcription to complete the synthesis of this mRNA will occur and if this mRNA will be used for translation. Beyond the transcriptional repression mechanism already discussed, attenuation also controls expression of the trp operon in E. coli ( Figure 11.38 ). The trp operon regulatory region contains a leader sequence called trpL between the operator and the first structural gene, which has four stretches of RNA that can base pair with each other in different combinations. When a terminator stem-loop forms, transcription terminates, releasing RNA polymerase from the mRNA. However, when an antiterminator stem-loop forms, this prevents the formation of the terminator stem-loop, so RNA polymerase can transcribe the structural genes. A related mechanism of concurrent regulation of transcription and translation in prokaryotes is the use of a riboswitch , a small region of noncoding RNA found within the 5’ end of some prokaryotic mRNA molecules ( Figure 11.39 . A riboswitch may bind to a small intracellular molecule to stabilize certain secondary structures of the mRNA molecule. The binding of the small molecule determines which stem-loop structure forms, thus influencing the completion of mRNA synthesis and protein synthesis. Other Factors Affecting Gene Expression in Prokaryotes and Eukaryotes Although the focus on our discussion of transcriptional control used prokaryotic operons as examples, eukaryotic transcriptional control is similar in many ways. As in prokaryotes, eukaryotic transcription can be controlled through the binding of transcription factors including repressor s and activator s. Interestingly, eukaryotic transcription can be influenced by the binding of proteins to regions of DNA, called enhancer s, rather far away from the gene, through DNA looping facilitated between the enhancer and the promoter ( Figure 11.40 ). Overall, regulating transcription is a highly effective way to control gene expression in both prokaryotes and eukaryotes. However, the control of gene expression in eukaryotes in response to environmental and cellular stresses can be accomplished in additional ways without the binding of transcription factors to regulatory regions. DNA-Level Control In eukaryotes, the DNA molecules or associated histones can be chemically modified in such a way as to influence transcription; this is called epigenetic regulation . Methylation of certain cytosine nucleotides in DNA in response to environmental factors has been shown to influence use of such DNA for transcription, with DNA methylation commonly correlating to lowered levels of gene expression. Additionally, in response to environmental factors, histone proteins for packaging DNA can also be chemically modified in multiple ways, including acetylation and deacetylation, influencing the packaging state of DNA and thus affecting the availability of loosely wound DNA for transcription. These chemical modifications can sometimes be maintained through multiple rounds of cell division, making at least some of these epigenetic changes heritable. Link to Learning This video describes how epigenetic regulation controls gene expression. Check Your Understanding What stops or allows transcription to proceed when attenuation is operating? What determines the state of a riboswitch? Describe the function of an enhancer. Describe two mechanisms of epigenetic regulation in eukaryotes. Clinical Focus Resolution Although Mark survived his bout with necrotizing fasciitis, he would now have to undergo a skin-grafting surgery, followed by long-term physical therapy. Based on the amount of muscle mass he lost, it is unlikely that his leg will return to full strength, but his physical therapist is optimistic that he will regain some use of his leg. Laboratory testing revealed the causative agent of Mark’s infection was a strain of Staphylococcus aureus . As required by law, Mark’s case was reported to the state health department and ultimately to the Centers for Disease Control and Prevention (CDC). At the CDC, the strain of Staphylococcus aureus strep isolated from Mark was analyzed more thoroughly for methicillin resistance. Methicillin resistance is genetically coded and is increasing among strains of S. aureus through horizontal gene transfer. Strains of S. aureus that are resistant to methicillin are typically resistant to virtually all beta-lactam antibiotics and other classes of antibiotics as well. In necrotizing fasciitis, blood flow to the infected area is typically limited because of the action of various genetically encoded bacterial toxins. This is why there is typically little to no bleeding as a result of the incision test. Unfortunately, these bacterial toxins limit the effectiveness of intravenous antibiotics in clearing infection from the skin and underlying tissue, meaning that antibiotic resistance alone does not explain the ineffectiveness of Mark’s treatment. Nevertheless, intravenous antibiotic therapy was warranted to help minimize the possible outcome of sepsis, which is a common outcome of necrotizing fasciitis. Through genomic analysis by the CDC of the strain isolated from Mark, several of the important virulence genes were shown to be encoded within pathogenicity islands that were associated with prophages. Horizontal transfer of pathogenicity island-encoded virulence factors between strains of S. aureus has been shown to occur through induction of prophage and can be induced by treatment with antibiotics. Go back to the previous Clinical Focus box.
principles_of_accounting,_volume_1:_financial_accounting
Summary 2.1 Describe the Income Statement, Statement of Owner’s Equity, Balance Sheet, and Statement of Cash Flows, and How They Interrelate Financial statements provide financial information to stakeholders to help them in making decisions. There are four financial statements: income statement, statement of owner’s equity, balance sheet, and statement of cash flows. The income statement measures the financial performance of the organization for a period of time. The income statement lists revenues, expenses, gains, and losses, which make up net income (or net loss). The statement of owner’s equity shows how the net worth of the organization changes for a period of time. In addition to showing net income or net loss, the statement of owner’s equity shows the investments by and distributions to owners. The balance sheet shows the organization’s financial position on a given date. The balance sheet lists assets, liabilities, and owners’ equity. The statement of cash flows shows the organization’s cash inflows and cash outflows for a given period of time. The statement of cash flows is necessary because financial statements are usually prepared using accrual accounting, which records transactions when they occur rather than waiting until cash is exchanged. 2.2 Define, Explain, and Provide Examples of Current and Noncurrent Assets, Current and Noncurrent Liabilities, Equity, Revenues, and Expenses Assets and liabilities are categorized into current and noncurrent, based on when the item will be settled. Assets and liabilities that will be settled in one year or less are classified as current; otherwise, the items are classified as noncurrent. Assets are also categorized based on whether or not the asset has physical substance. Assets with physical substance are considered tangible assets, while intangible assets lack physical substance. The distinction between current and noncurrent assets and liabilities is important because it helps financial statement users assess the timing of the transactions. Three broad categories of legal business structures are sole proprietorship, partnership, and corporation, with each structure having advantages and disadvantages. The accounting equation is Assets = Liabilities + Owner’s Equity. It is important to the study of accounting because it shows what the organization owns and the sources of (or claims against) those resources. Owners’ equity can also be thought of as the net worth or value of the business. There are many factors that influence equity, including net income or net loss, investments by and distributions to owners, revenues, gains, losses, expenses, and comprehensive income. 2.3 Prepare an Income Statement, Statement of Owner’s Equity, and Balance Sheet There are ten financial statement elements: revenues, expenses, gains, losses, assets, liabilities, equity, investments by owners, distributions to owners, and comprehensive income. There are standard conventions for the order of preparing financial statements (income statement, statement of owner’s equity, balance sheet, and statement of cash flows) and for the format (three-line heading and columnar structure). Financial ratios, which are calculated using financial statement information, are often beneficial to aid in financial decision-making. Ratios allow for comparisons between businesses and determining trends between periods within the same business. Liquidity ratios assess the firm’s ability to convert assets into cash. Working Capital (Current Assets – Current Liabilities) is a liquidity ratio that measures a firm’s ability to meet current obligations. The Current Ratio (Current Assets/Current Liabilities) is similar to Working Capital but allows for comparisons between firms by determining the proportion of current assets to current liabilities.
Chapter Outline 2.1 Describe the Income Statement, Statement of Owner’s Equity, Balance Sheet, and Statement of Cash Flows, and How They Interrelate 2.2 Define, Explain, and Provide Examples of Current and Noncurrent Assets, Current and Noncurrent Liabilities, Equity, Revenues, and Expenses 2.3 Prepare an Income Statement, Statement of Owner’s Equity, and Balance Sheet Why It Matters As a teenager, Derek loves computers. He also enjoys giving back to the community by helping others. Derek understands that many senior citizens live far away from their families, resulting in infrequent visits and loneliness. This summer he is considering combining both things he enjoys by working with the local retirement center. His idea is to have workshops to show the senior citizens how to connect with their families through the use of technology. The director of the retirement center is enthused about Derek’s idea and has agreed to pay him for the services. During his visits, he will set up tablets and then show the seniors how to use them. Since he lives nearby, he will also provide support on an as-needed basis. While he is excited about this opportunity, he is also trying to save up money for college. Although the retirement center will pay him for the workshops, he knows the investment in providing tablets will be expensive, and he wants to ensure he can cover his costs. A neighbor who works in banking suggests that Derek get a small loan to cover the costs of the tablets and use the income he earns to repay the loan. Derek is excited by the idea but is anxious when his neighbor mentions he will have to provide the bank monthly financial information, such as checking account and other financial statements. While he enjoys technology and helping others, he is unfamiliar with financial statements. Derek decides to learn more about how financial statements will help both him and the bank make sound financial decisions.
[ { "answer": { "ans_choice": 3, "ans_text": "D" }, "bloom": null, "hl_context": "In Describe the Income Statement , Statement of Owner ’ s Equity , Balance Sheet , and Statement of Cash Flows , and How They Interrelate , we discussed the function of and the basic characteristics of the statement of cash flows . This fourth and final financial statement lists the cash inflows and cash outflows for the business for a period of time . <hl> It was created to fill in some informational gaps that existed in the other three statements ( income statement , owner ’ s equity / retained earnings statement , and the balance sheet ) . <hl> A full demonstration of the creation of the statement of cash flows is presented in Statement of Cash Flows . <hl> The fourth and final financial statement prepared is the statement of cash flows , which is a statement that lists the cash inflows and cash outflows for the business for a period of time . <hl> At first glance , this may seem like a redundant financial statement . <hl> We know the income statement also reports the inflows and outflows for the business for a period of time . <hl> <hl> In addition , the statement of owner ’ s equity and the balance sheet help to show the other activities , such as investments by and distributions to owners that are not included in the income statement . <hl> To understand why the statement of cash flows is necessary , we must first understand the two bases of accounting used to prepare the financial statements . The changes in cash within this statement are often referred to as sources and uses of cash . A source of cash lets one see where cash is coming from . For example , is cash being generated from sales to customers , or is the cash a result of an advance in a large loan . Use of cash looks at what cash is being used for . Is cash being used to make an interest payment on a loan , or is cash being used to purchase a large piece of machinery that will expand business capacity ? The two bases of accounting are the cash basis and the accrual basis , briefly introduced in Describe the Income Statement , Statement of Owner ’ s Equity , Balance Sheet , and Statement of Cash Flows , and How They Interrelate .", "hl_sentences": "It was created to fill in some informational gaps that existed in the other three statements ( income statement , owner ’ s equity / retained earnings statement , and the balance sheet ) . The fourth and final financial statement prepared is the statement of cash flows , which is a statement that lists the cash inflows and cash outflows for the business for a period of time . We know the income statement also reports the inflows and outflows for the business for a period of time . In addition , the statement of owner ’ s equity and the balance sheet help to show the other activities , such as investments by and distributions to owners that are not included in the income statement .", "question": { "cloze_format": "The statement that is not one of the financial statements is the ___.", "normal_format": "Which of these statements is not one of the financial statements?", "question_choices": [ "income statement", "balance sheet", "statement of cash flows", "statement of owner investments" ], "question_id": "fs-idm385189632", "question_text": "Which of these statements is not one of the financial statements?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 3, "ans_text": "competitors" }, "bloom": null, "hl_context": "Before exploring the specific financial statements , it is important to know why these are important documents . To understand this , you must first understand who the users of financial statements are . Users of the information found in financial statements are called stakeholders . <hl> A stakeholder is someone affected by decisions made by a company ; this can include groups or individuals affected by the actions or policies of an organization , including include investors , creditors , employees , managers , regulators , customers , and suppliers . <hl> <hl> The stakeholder ’ s interest sometimes is not directly related to the entity ’ s financial performance . <hl> <hl> Examples of stakeholders include lenders , investors / owners , vendors , employees and management , governmental agencies , and the communities in which the businesses operate . <hl> Stakeholders are interested in the performance of an organization for various reasons , but the common goal of using the financial statements is to understand the information each contains that is useful for making financial decisions . For example , a banker may be interested in the financial statements to decide whether or not to lend the organization money .", "hl_sentences": "A stakeholder is someone affected by decisions made by a company ; this can include groups or individuals affected by the actions or policies of an organization , including include investors , creditors , employees , managers , regulators , customers , and suppliers . The stakeholder ’ s interest sometimes is not directly related to the entity ’ s financial performance . Examples of stakeholders include lenders , investors / owners , vendors , employees and management , governmental agencies , and the communities in which the businesses operate .", "question": { "cloze_format": "Stakeholders are less likely to include ___.", "normal_format": "Stakeholders are less likely to include which of the following groups?", "question_choices": [ "owners", "employees", "community leaders", "competitors" ], "question_id": "fs-idm370303680", "question_text": "Stakeholders are less likely to include which of the following groups?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 0, "ans_text": "A" }, "bloom": null, "hl_context": "In accounting , this example illustrates an income statement , a financial statement that is used to measure the financial performance of an organization for a particular period of time . <hl> We use the simple landscaping account example to discuss the elements of the income statement , which are revenues , expenses , gains , and losses . <hl> Together , these determine whether the organization has net income ( where revenues and gains are greater than expenses and losses ) or net loss ( where expenses and losses are greater than revenues and gains ) . Revenues , expenses , gains , and losses are further defined here .", "hl_sentences": "We use the simple landscaping account example to discuss the elements of the income statement , which are revenues , expenses , gains , and losses .", "question": { "cloze_format": "The correct components of the income statement can be listed as ___.", "normal_format": "What are the correct components of the income statement?", "question_choices": [ "revenues, losses, expenses, and gains", "assets, liabilities, and owner’s equity", "revenues, expenses, investments by owners, distributions to owners", "assets, liabilities, and dividends" ], "question_id": "fs-idm359834736", "question_text": "Identify the correct components of the income statement." }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 2, "ans_text": "assets, liabilities, and investments by owners" }, "bloom": null, "hl_context": "Knowing the difference between the cash basis and accrual basis of accounting is necessary to understand the need for the statement of cash flows . <hl> Stakeholders need to know the financial performance ( as measured by the income statement — that is , net income or net loss ) and financial position ( as measured by the balance sheet — that is , assets , liabilities , and owners ’ equity ) of the business . <hl> This information is provided in the income statement , statement of owner ’ s equity , and balance sheet . However , since these financial statements are prepared using accrual accounting , stakeholders do not have a clear picture of the business ’ s cash activities . The statement of cash flows solves this inadequacy by specifically focusing on the cash inflows and cash outflows . 2.2 Define , Explain , and Provide Examples of Current and Noncurrent Assets , Current and Noncurrent Liabilities , Equity , Revenues , and Expenses", "hl_sentences": "Stakeholders need to know the financial performance ( as measured by the income statement — that is , net income or net loss ) and financial position ( as measured by the balance sheet — that is , assets , liabilities , and owners ’ equity ) of the business .", "question": { "cloze_format": "The balance sheet lists ___.", "normal_format": "The balance sheet lists which of the following?", "question_choices": [ "assets, liabilities, and owners’ equity", "revenues, expenses, gains, and losses", "assets, liabilities, and investments by owners", "revenues, expenses, gains, and distributions to owners" ], "question_id": "fs-idm384816368", "question_text": "The balance sheet lists which of the following?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 2, "ans_text": "Tangible assets have physical substance." }, "bloom": null, "hl_context": "Another thing you might have recognized when reviewing your list of coffee shop assets is that all of the items were something you could touch or move , each of which is known as a tangible asset . However , as you also learned in Describe the Income Statement , Statement of Owner ’ s Equity , Balance Sheet , and Statement of Cash Flows , and How They Interrelate , not all assets are tangible . <hl> An asset could be an intangible asset , meaning the item lacks physical substance — it cannot be touched or moved . <hl> Take a moment to think about your favorite type of shoe or a popular type of farm tractor . Would you be able to recognize the maker of that shoe or the tractor by simply seeing the logo ? Chances are you would . These are examples of intangible assets , trademarks to be precise . A trademark has value to the organization that created ( or purchased ) the trademark , and the trademark is something the organization controls — others cannot use the trademark without permission . An asset can also be categorized as a tangible asset or an intangible asset . <hl> Tangible assets have a physical nature , such as trucks or many inventory items , while intangible assets have value but often lack a physical existence or corpus , such as insurance policies or trademarks . <hl>", "hl_sentences": "An asset could be an intangible asset , meaning the item lacks physical substance — it cannot be touched or moved . Tangible assets have a physical nature , such as trucks or many inventory items , while intangible assets have value but often lack a physical existence or corpus , such as insurance policies or trademarks .", "question": { "cloze_format": "The statement that is true is that ___.", "normal_format": "Which of the following statements is true?", "question_choices": [ "Tangible assets lack physical substance.", "Tangible assets will be consumed in a year or less.", "Tangible assets have physical substance.", "Tangible assets will be consumed in over a year." ], "question_id": "fs-idm406688976", "question_text": "Which of the following statements is true?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 0, "ans_text": "A" }, "bloom": null, "hl_context": "<hl> A corporation is a legal business structure involving one or more individuals ( owners ) who are legally distinct ( separate ) from the business . <hl> A primary benefit of a corporate legal structure is the owners of the organization have limited liability . That is , a corporation is “ stand alone , ” conducting business as an entity separate from its owners . Under the corporate structure , owners delegate to others ( called agents ) the responsibility to make day-to-day decisions regarding the operations of the business . Other benefits of the corporate legal structure include relatively easy access to large amounts of capital by obtaining loans or selling ownership ( stock ) , and since the stock is easily sold or transferred to others , the business operates beyond the life of the shareholders . A major disadvantage of a corporate legal structure is double taxation — the business pays income tax and the owners are taxed when distributions ( also called dividends ) are received .", "hl_sentences": "A corporation is a legal business structure involving one or more individuals ( owners ) who are legally distinct ( separate ) from the business .", "question": { "cloze_format": "Under the legal business structure of ___, owners have no personal liability. ", "normal_format": "Owners have no personal liability under which legal business structure?", "question_choices": [ "a corporation", "a partnership", "a sole proprietorship", "There is liability in every legal business structure." ], "question_id": "fs-idm369250368", "question_text": "Owners have no personal liability under which legal business structure?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 3, "ans_text": "Assets = Liabilities + Owner’s Equity" }, "bloom": null, "hl_context": "Your Turn The Accounting Equation On a sheet of paper , use three columns to create your own accounting equation . <hl> In the first column , list all of the things you own ( assets ) . <hl> <hl> In the second column , list any amounts owed ( liabilities ) . <hl> <hl> In the third column , using the accounting equation , calculate , you guessed it , the net amount of the asset ( equity ) . <hl> When finished , total the columns to determine your net worth . Hint : do not forget to subtract the liability from the value of the asset .", "hl_sentences": "In the first column , list all of the things you own ( assets ) . In the second column , list any amounts owed ( liabilities ) . In the third column , using the accounting equation , calculate , you guessed it , the net amount of the asset ( equity ) .", "question": { "cloze_format": "The accounting equation is expressed as ________.", "normal_format": "What is the accounting equation?", "question_choices": [ "Assets + Liabilities = Owner’s Equity", "Assets – Noncurrent Assets = Liabilities", "Assets = Liabilities + Investments by Owners", "Assets = Liabilities + Owner’s Equity" ], "question_id": "fs-idm369458480", "question_text": "The accounting equation is expressed as ________." }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 1, "ans_text": "B" }, "bloom": null, "hl_context": "<hl> The elements of the financial statements shown on the statement of owner ’ s equity include investments by owners as well as distributions to owners . <hl> Investments by owners and distributions to owners are two activities that impact the value of the organization ( increase and decrease , respectively ) . <hl> In addition , net income or net loss affects the value of the organization ( net income increases the value of the organization , and net loss decreases it ) . <hl> Net income ( or net loss ) is also shown on the statement of owner ’ s equity ; this is an example of how the statements are interrelated . Note that the word owner ’ s ( singular for a sole owner ) changes to owners ’ ( plural , for a group of owners ) when preparing this statement for an entity with multiple owners versus a sole proprietorship .", "hl_sentences": "The elements of the financial statements shown on the statement of owner ’ s equity include investments by owners as well as distributions to owners . In addition , net income or net loss affects the value of the organization ( net income increases the value of the organization , and net loss decreases it ) .", "question": { "cloze_format": "___ decreases owner’s equity.", "normal_format": "Which of the following decreases owner’s equity?", "question_choices": [ "investments by owners", "losses", "gains", "short-term loans" ], "question_id": "fs-idm380967216", "question_text": "Which of the following decreases owner’s equity?" }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 1, "ans_text": "no impact on equity" }, "bloom": null, "hl_context": "<hl> Exchanges of assets for assets <hl> As you continue to develop your understanding of accounting , you will encounter many types of transactions involving different elements of the financial statements . The previous examples highlighted elements that change the equity of an organization . Not all transactions , however , ultimately impact equity . <hl> For example , the following do not impact the equity or net worth of the organization : 10 10 SFAC No . <hl> 6 , p . 20 .", "hl_sentences": "Exchanges of assets for assets For example , the following do not impact the equity or net worth of the organization : 10 10 SFAC No .", "question": { "cloze_format": "The effect on equity that exchanges of assets for assets have is that (they (have)) ___.", "normal_format": "Exchanges of assets for assets have what effect on equity?", "question_choices": [ "increase equity", "no impact on equity", "decrease equity", "There is no relationship between assets and equity." ], "question_id": "fs-idm381340624", "question_text": "Exchanges of assets for assets have what effect on equity?" }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 3, "ans_text": "D" }, "bloom": null, "hl_context": "<hl> Acquisitions of assets by incurring liabilities <hl> As you continue to develop your understanding of accounting , you will encounter many types of transactions involving different elements of the financial statements . The previous examples highlighted elements that change the equity of an organization . Not all transactions , however , ultimately impact equity . <hl> For example , the following do not impact the equity or net worth of the organization : 10 10 SFAC No . <hl> 6 , p . 20 .", "hl_sentences": "Acquisitions of assets by incurring liabilities For example , the following do not impact the equity or net worth of the organization : 10 10 SFAC No .", "question": { "cloze_format": "All of the following increase owner’s equity except ___", "normal_format": "All of the following increase owner’s equity except for which one?", "question_choices": [ "gains", "investments by owners", "revenues", "acquisitions of assets by incurring liabilities" ], "question_id": "fs-idm395691424", "question_text": "All of the following increase owner’s equity except for which one?" }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 0, "ans_text": "future potential sales price of inventory" }, "bloom": null, "hl_context": "<hl> Elements of the Financial Statements <hl> <hl> The statement of owner ’ s equity , which is the second financial statement created by accountants , is a statement that shows how the equity ( or value ) of the organization has changed over time . <hl> Similar to the income statement , the statement of owner ’ s equity is for a specific period of time , typically one year . Recall that another way to think about equity is net worth , or value . So , the statement of owner ’ s equity is a financial statement that shows how the net worth , or value , of the business has changed for a given period of time . In essence , the overall purpose of financial statements is to evaluate the performance of a company , governmental entity , or not-for-profit entity . This chapter illustrates this through a company , which is considered to be in business to generate a profit . <hl> Each financial statement we examine has a unique function , and together they provide information to determine whether a company generated a profit or loss for a given period ( such as a month , quarter , or year ); the assets , which are resources of the company , and accompanying liabilities , which are obligations of the company , that are used to generate the profit or loss ; owner interest in profits or losses ; and the cash position of the company at the end of the period . <hl>", "hl_sentences": "Elements of the Financial Statements The statement of owner ’ s equity , which is the second financial statement created by accountants , is a statement that shows how the equity ( or value ) of the organization has changed over time . Each financial statement we examine has a unique function , and together they provide information to determine whether a company generated a profit or loss for a given period ( such as a month , quarter , or year ); the assets , which are resources of the company , and accompanying liabilities , which are obligations of the company , that are used to generate the profit or loss ; owner interest in profits or losses ; and the cash position of the company at the end of the period .", "question": { "cloze_format": "___ is not an element of the financial statements.", "normal_format": "Which of the following is not an element of the financial statements?", "question_choices": [ "future potential sales price of inventory", "assets", "liabilities", "equity" ], "question_id": "fs-idm339789968", "question_text": "Which of the following is not an element of the financial statements?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 1, "ans_text": "B" }, "bloom": null, "hl_context": "In this example using a fictitious company , Cheesy Chuck ’ s , we began with the account balances and demonstrated how to prepare the financial statements for the month of June , the first month of operations for the business . <hl> It will be helpful to revisit the process by summarizing the information we started with and how that information was used to create the four financial statements : income statement , statement of owner ’ s equity , balance sheet , and statement of cash flows . <hl>", "hl_sentences": "It will be helpful to revisit the process by summarizing the information we started with and how that information was used to create the four financial statements : income statement , statement of owner ’ s equity , balance sheet , and statement of cash flows .", "question": { "cloze_format": "___ is the correct order of preparing the financial statements.", "normal_format": "Which of the following is the correct order of preparing the financial statements?", "question_choices": [ "income statement, statement of cash flows, balance sheet, statement of owner’s equity", "income statement, statement of owner’s equity, balance sheet, statement of cash flows", "income statement, balance sheet, statement of owner’s equity, statement of cash flows", "income statement, balance sheet, statement of cash flows, statement of owner’s equity" ], "question_id": "fs-idm383825312", "question_text": "Which of the following is the correct order of preparing the financial statements?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 0, "ans_text": "company, statement title, time period of report" }, "bloom": null, "hl_context": "<hl> The last line indicates the time frame of the financial statement . <hl> Do not forget the income statement is for a period of time ( the month of June in our example ) . <hl> The middle line indicates the financial statement that is being presented . <hl> <hl> The first line lists the business name . <hl> <hl> The heading of the income statement includes three lines . <hl>", "hl_sentences": "The last line indicates the time frame of the financial statement . The middle line indicates the financial statement that is being presented . The first line lists the business name . The heading of the income statement includes three lines .", "question": { "cloze_format": "The three heading lines of financial statements typically include ___ .", "normal_format": "The three heading lines of financial statements typically include which of the following?", "question_choices": [ "company, statement title, time period of report", "company headquarters, statement title, name of preparer", "statement title, time period of report, name of preparer", "name of auditor, statement title, fiscal year end" ], "question_id": "fs-idm374265504", "question_text": "The three heading lines of financial statements typically include which of the following?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 2, "ans_text": "C" }, "bloom": null, "hl_context": "<hl> Knowing the difference between the cash basis and accrual basis of accounting is necessary to understand the need for the statement of cash flows . <hl> <hl> Stakeholders need to know the financial performance ( as measured by the income statement — that is , net income or net loss ) and financial position ( as measured by the balance sheet — that is , assets , liabilities , and owners ’ equity ) of the business . <hl> This information is provided in the income statement , statement of owner ’ s equity , and balance sheet . However , since these financial statements are prepared using accrual accounting , stakeholders do not have a clear picture of the business ’ s cash activities . The statement of cash flows solves this inadequacy by specifically focusing on the cash inflows and cash outflows . 2.2 Define , Explain , and Provide Examples of Current and Noncurrent Assets , Current and Noncurrent Liabilities , Equity , Revenues , and Expenses <hl> The fourth and final financial statement prepared is the statement of cash flows , which is a statement that lists the cash inflows and cash outflows for the business for a period of time . <hl> At first glance , this may seem like a redundant financial statement . We know the income statement also reports the inflows and outflows for the business for a period of time . In addition , the statement of owner ’ s equity and the balance sheet help to show the other activities , such as investments by and distributions to owners that are not included in the income statement . To understand why the statement of cash flows is necessary , we must first understand the two bases of accounting used to prepare the financial statements . The changes in cash within this statement are often referred to as sources and uses of cash . A source of cash lets one see where cash is coming from . For example , is cash being generated from sales to customers , or is the cash a result of an advance in a large loan . Use of cash looks at what cash is being used for . Is cash being used to make an interest payment on a loan , or is cash being used to purchase a large piece of machinery that will expand business capacity ? The two bases of accounting are the cash basis and the accrual basis , briefly introduced in Describe the Income Statement , Statement of Owner ’ s Equity , Balance Sheet , and Statement of Cash Flows , and How They Interrelate .", "hl_sentences": "Knowing the difference between the cash basis and accrual basis of accounting is necessary to understand the need for the statement of cash flows . Stakeholders need to know the financial performance ( as measured by the income statement — that is , net income or net loss ) and financial position ( as measured by the balance sheet — that is , assets , liabilities , and owners ’ equity ) of the business . The fourth and final financial statement prepared is the statement of cash flows , which is a statement that lists the cash inflows and cash outflows for the business for a period of time .", "question": { "cloze_format": "The financial statement that shows the financial performance of the company on a cash basis is called the ___.", "normal_format": "Which financial statement shows the financial performance of the company on a cash basis?", "question_choices": [ "balance sheet", "statement of owner’s equity", "statement of cash flows", "income statement" ], "question_id": "fs-idm347423312", "question_text": "Which financial statement shows the financial performance of the company on a cash basis?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 0, "ans_text": "balance sheet" }, "bloom": null, "hl_context": "<hl> The third financial statement created is the balance sheet , which shows the company ’ s financial position on a given date . <hl> Cheesy Chuck ’ s balance sheet is shown in Figure 2.13 . <hl> The balance sheet summarizes the financial position of the business on a given date . <hl> Meaning , because of the financial performance over the past twelve months , for example , this is the financial position of the business as of December 31 . Think of the balance sheet as being similar to a team ’ s overall win / loss record — to a certain extent a team ’ s strength can be perceived by its win / loss record .", "hl_sentences": "The third financial statement created is the balance sheet , which shows the company ’ s financial position on a given date . The balance sheet summarizes the financial position of the business on a given date .", "question": { "cloze_format": "The financial statement that shows the financial position of the company is the ___ .", "normal_format": "Which financial statement shows the financial position of the company?", "question_choices": [ "balance sheet", "statement of owner’s equity", "statement of cash flows", "income statement" ], "question_id": "fs-idm374579344", "question_text": "Which financial statement shows the financial position of the company?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 2, "ans_text": "C" }, "bloom": null, "hl_context": "<hl> The starting point for understanding liquidity ratios is to define working capital — current assets minus current liabilities . <hl> Recall that current assets and current liabilities are amounts generally settled in one year or less . <hl> Working capital ( current assets minus current liabilities ) is used to assess the dollar amount of assets a business has available to meet its short-term liabilities . <hl> A positive working capital amount is desirable and indicates the business has sufficient current assets to meet short-term obligations ( liabilities ) and still has financial flexibility . A negative amount is undesirable and indicates the business should pay particular attention to the composition of the current assets ( that is , how liquid the current assets are ) and to the timing of the current liabilities . It is unlikely that all of the current liabilities will be due at the same time , but the amount of working capital gives stakeholders of both small and large businesses an indication of the firm ’ s ability to meet its short-term obligations .", "hl_sentences": "The starting point for understanding liquidity ratios is to define working capital — current assets minus current liabilities . Working capital ( current assets minus current liabilities ) is used to assess the dollar amount of assets a business has available to meet its short-term liabilities .", "question": { "cloze_format": "Working capital is an indication of the firm’s ________.", "normal_format": "Working capital is an indication of the firm’s which of the following?", "question_choices": [ "asset utilization", "amount of noncurrent liabilities", "liquidity", "amount of noncurrent assets" ], "question_id": "fs-idm377566608", "question_text": "Working capital is an indication of the firm’s ________." }, "references_are_paraphrase": null } ]
2
2.1 Describe the Income Statement, Statement of Owner’s Equity, Balance Sheet, and Statement of Cash Flows, and How They Interrelate The study of accounting requires an understanding of precise and sometimes complicated terminology, purposes, principles, concepts, and organizational and legal structures. Typically, your introductory accounting courses will familiarize you with the overall accounting environment, and for those of you who want greater detail, there is an assortment of more advanced accounting courses available. This chapter concentrates on the four major types of financial statements and their interactions, the major types of business structures, and some of the major terms and concepts used in this course. Coverage here is somewhat basic since these topics are accorded much greater detail in future chapters. Types of Business Structure As you learned in Role of Accounting in Society , virtually every activity that occurs in a business has an associated cost or value. Part of an accountant’s role is to quantify these activities, or transactions. Also, in business—and accounting in particular—it is necessary to distinguish the business entity from the individual owner(s). The personal transactions of the owners, employees, and other parties connected to the business should not be recorded in the organization’s records; this accounting principle is called the business entity concept . Accountants should record only business transactions in business records. This separation is also reflected in the legal structure of the business. There are several common types of legal business structures. While the accounting concepts for the various types of businesses are essentially the same regardless of the legal structure, the terminology will change slightly depending on the organization’s legal structure, and it is important to understand the differences. There are three broad categories for the legal structure of an organization: sole proprietorship, partnership, and corporation. A sole proprietorship is a legal business structure consisting of a single individual. Benefits of this type of structure include ease of formation, favorable tax treatment, and a high level of control over the business. The risks involved with sole proprietorships include unlimited personal liability and a limited life for the business. Unless the business is sold, the business ends when the owner retires or passes away. In addition, sole proprietorships have a fairly limited ability to raise capital (funding), and often sole proprietors have limited expertise—they are excellent at what they do but may have limited expertise in other important areas of business, such as accounting or marketing. A partnership is a legal business structure consisting of an association of two or more people who contribute money, property, or services to operate as co-owners of a business. Benefits of this type of structure include favorable tax treatment, ease of formation of the business, and better access to capital and expertise. The downsides to a partnership include unlimited personal liability (although there are other legal structures—a limited liability partnership, for example—to help mitigate the risk); limited life of the partnership, similar to sole proprietorships; and increased complexity to form the venture (decision-making authority, profit-sharing arrangement, and other important issues need to be formally articulated in a written partnership agreement). A corporation is a legal business structure involving one or more individuals (owners) who are legally distinct (separate) from the business. A primary benefit of a corporate legal structure is the owners of the organization have limited liability. That is, a corporation is “stand alone,” conducting business as an entity separate from its owners. Under the corporate structure, owners delegate to others (called agents) the responsibility to make day-to-day decisions regarding the operations of the business. Other benefits of the corporate legal structure include relatively easy access to large amounts of capital by obtaining loans or selling ownership (stock), and since the stock is easily sold or transferred to others, the business operates beyond the life of the shareholders. A major disadvantage of a corporate legal structure is double taxation—the business pays income tax and the owners are taxed when distributions (also called dividends) are received. Types of Business Structures   Sole Proprietorship Partnership Corporation Number of Owners Single individual Two or more individuals One or more owners Ease of Formation Easier to form Harder to form Difficult to form Ability to Raise Capital Difficult to raise capital Harder to raise capital Easier to raise capital Liability Risk Unlimited liability Unlimited liability Limited liability Taxation Consideration Single taxation Single taxation Double taxation Table 2.1 The Four Financial Statements Are you a fan of books, movies, or sports? If so, chances are you have heard or said the phrase “spoiler alert.” It is used to forewarn readers, viewers, or fans that the ending of a movie or book or outcome of a game is about to be revealed. Some people prefer knowing the end and skipping all of the details in the middle, while others prefer to fully immerse themselves and then discover the outcome. People often do not know or understand what accountants produce or provide. That is, they are not familiar with the “ending” of the accounting process, but that is the best place to begin the study of accounting. Accountants create what are known as financial statements. Financial statements are reports that communicate the financial performance and financial position of the organization. In essence, the overall purpose of financial statements is to evaluate the performance of a company, governmental entity, or not-for-profit entity. This chapter illustrates this through a company, which is considered to be in business to generate a profit. Each financial statement we examine has a unique function, and together they provide information to determine whether a company generated a profit or loss for a given period (such as a month, quarter, or year); the assets, which are resources of the company, and accompanying liabilities, which are obligations of the company, that are used to generate the profit or loss; owner interest in profits or losses; and the cash position of the company at the end of the period. The four financial statements that perform these functions and the order in which we prepare them are: Income Statement Statement of Owner’s Equity Balance Sheet Statement of Cash Flows. The order of preparation is important as it relates to the concept of how financial statements are interrelated. Before explaining each in detail, let’s explore the purpose of each financial statement and its main components. Continuing Application Introduction to the Gearhead Outfitters Story Gearhead Outfitters , founded by Ted Herget in 1997 in Jonesboro, Arkansas, is a retail chain that sells outdoor gear for men, women, and children. The company’s inventory includes clothing, footwear for hiking and running, camping gear, backpacks, and accessories, by brands such as The North Face , Birkenstock , Wolverine , Yeti , Altra , Mizuno , and Patagonia . Herget fell in love with the outdoor lifestyle while working as a ski instructor in Colorado and wanted to bring that feeling back home to Arkansas. And so, Gearhead was born in a small downtown location in Jonesboro. The company has had great success over the years, expanding to numerous locations in Herget’s home state, as well as Louisiana, Oklahoma, and Missouri. While Herget knew his industry when starting Gearhead , like many entrepreneurs he faced regulatory and financial issues that were new to him. Several of these issues were related to accounting and the wealth of decision-making information that accounting systems provide. For example, measuring revenue and expenses, providing information about cash flow to potential lenders, analyzing whether profit and positive cash flow is sustainable to allow for expansion, and managing inventory levels. Accounting, or the preparation of financial statements (balance sheet, income statement, and statement of cash flows), provides the mechanism for business owners such as Herget to make fundamentally sound business decisions. Purpose of Financial Statements Before exploring the specific financial statements, it is important to know why these are important documents. To understand this, you must first understand who the users of financial statements are. Users of the information found in financial statements are called stakeholders. A stakeholder is someone affected by decisions made by a company; this can include groups or individuals affected by the actions or policies of an organization, including include investors, creditors, employees, managers, regulators, customers, and suppliers. The stakeholder’s interest sometimes is not directly related to the entity’s financial performance. Examples of stakeholders include lenders, investors/owners, vendors, employees and management, governmental agencies, and the communities in which the businesses operate. Stakeholders are interested in the performance of an organization for various reasons, but the common goal of using the financial statements is to understand the information each contains that is useful for making financial decisions. For example, a banker may be interested in the financial statements to decide whether or not to lend the organization money. Likewise, small business owners may make decisions based on their familiarity with the business—they know if the business is doing well or not based on their “gut feeling.” By preparing the financial statements, accountants can help owners by providing clarity of the organization’s financial performance. It is important to understand that, in the long term, every activity of the business has a financial impact, and financial statements are a way that accountants report the activities of the business. Stakeholders must make many decisions, and the financial statements provide information that is helpful in the decision-making process. As described in Role of Accounting in Society , the complete set of financial statements acts as an X-ray of a company’s financial health. By evaluating all of the financial statements together, someone with financial knowledge can determine the overall health of a company. The accountant can use this information to advise outside (and inside) stakeholders on decisions, and management can use this information as one tool to make strategic short- and long-term decisions. Ethical Considerations Utilitarian View of Accounting Decisions and Stakeholder Well-Being Utilitarianism is a well-known and influential moral theory commonly used as a framework to evaluate business decisions. Utilitarianism suggests that an ethical action is one whose consequence achieves the greatest good for the greatest number of people. So, if we want to make an ethical decision, we should ask ourselves who is helped and who is harmed by it. Focusing on consequences in this way generally does not require us to take into account the means of achieving that particular end, however. Put simply, the utilitarian view is an ethical theory that the best action of a company is the one that maximizes utility of all stakeholders to the decision. This view assumes that all individuals with an interest in the business are considered within the decision. Financial statements are used to understand the financial performance of companies and to make long- and short-term decisions. A utilitarian approach considers all stakeholders, and both the long- and short-term effects of a business decision. This allows corporate decision makers to choose business actions with the potential to produce the best outcomes for the majority of all stakeholders, not just shareholders, and therefore maximize stakeholder happiness. Accounting decisions can change the approach a stakeholder has in relation to a business. If a company focuses on modifying operations and financial reporting to maximize short-term shareholder value, this could indicate the prioritization of certain stakeholder interests above others. When a company pursues only short-term profit for shareholders, it neglects the well-being of other stakeholders. Professional accountants should be aware of the interdependent relationship between all stakeholders and consider whether the results of their decisions are good for the majority of stakeholder interests. Your Turn Business Owners as Decision Makers Think of a business owner in your family or community. Schedule some time to talk with the business owner, and find out how he or she uses financial information to make decisions. Solution Business owners will use financial information for many decisions, such as comparing sales from one period to another, determining trends in costs and other expenses, and identifying areas in which to reduce or reallocate expenses. This information will be used to determine, for example, staffing and inventory levels, streamlining of operations, and advertising or other investment decisions. The Income Statement The first financial statement prepared is the income statement , a statement that shows the organization’s financial performance for a given period of time . Let’s illustrate the purpose of an income statement using a real-life example. Assume your friend, Chris, who is a sole proprietor, started a summer landscaping business on August 1, 2020. It is categorized as a service entity. To keep this example simple, assume that she is using her family’s tractor, and we are using the cash basis method of accounting to demonstrate Chris’s initial operations for her business. The other available basis method that is commonly used in accounting is the accrual basis method. She is responsible for paying for fuel and any maintenance costs. She named the business Chris’ Landscaping. On August 31, Chris checked the account balance and noticed there is only $250 in the checking account. This balance is lower than expected because she thought she had been paid by some customers. Chris decides to do some research to determine why the balance in the checking account is lower than expected. Her research shows that she earned a total of $1,400 from her customers but had to pay $100 to fix the brakes on her tractor, $50 for fuel, and also made a $1,000 payment to the insurance company for business insurance. The reason for the lower-than-expected balance was due to the fact that she spent ($1,150 for brakes, fuel, and insurance) only slightly less than she earned ($1,400)—a net increase of $250. While she would like the checking balance to grow each month, she realizes most of the August expenses were infrequent (brakes and insurance) and the insurance, in particular, was an unusually large expense. She is convinced the checking account balance will likely grow more in September because she will earn money from some new customers; she also anticipates having fewer expenses. The Income Statement can also be visualized by the formula: Revenue – Expenses = Net Income/(Loss). Let’s change this example slightly and assume the $1,000 payment to the insurance company will be paid in September, rather than in August. In this case, the ending balance in Chris’s checking account would be $1,250, a result of earning $1,400 and only spending $100 for the brakes on her car and $50 for fuel. This stream of cash flows is an example of cash basis accounting because it reflects when payments are received and made, not necessarily the time period that they affect. At the end of this section and in The Adjustment Process you will address accrual accounting, which does reflect the time period that they affect. In accounting, this example illustrates an income statement, a financial statement that is used to measure the financial performance of an organization for a particular period of time. We use the simple landscaping account example to discuss the elements of the income statement, which are revenues, expenses, gains, and losses. Together, these determine whether the organization has net income (where revenues and gains are greater than expenses and losses) or net loss (where expenses and losses are greater than revenues and gains). Revenues, expenses, gains, and losses are further defined here. Revenue Revenue 1 is the value of goods and services the organization sold or provided to customers for a given period of time. In our current example, Chris’s landscaping business, the “revenue” earned for the month of August would be $1,400. It is the value Chris received in exchange for the services provided to her clients. Likewise, when a business provides goods or services to customers for cash at the time of the service or in the future, the business classifies the amount(s) as revenue. Just as the $1,400 earned from a business made Chris’s checking account balance increase, revenues increase the value of a business. In accounting, revenues are often also called sales or fees earned. Just as earning wages from a business or summer job reflects the number of hours worked for a given rate of pay or payments from clients for services rendered, revenues (and the other terms) are used to indicate the dollar value of goods and services provided to customers for a given period of time. 1 In a subsequent section of this chapter, you will learn that the accounting profession is governed by the Financial Accounting Standards Board (or FASB), a professional body that issues guidelines/pronouncements for the accounting profession. A set of theoretical pronouncements issued by FASB is called Statement of Financial Accounting Concepts (SFAC). In SFAC No. 6, FASB defines revenues as “inflows or other enhancements of assets of an entity or settlements of its liabilities (or a combination of both) from delivering or producing goods, rendering services, or other activities that constitute the entity’s ongoing major or central operations” (SFAC No. 6, p. 23). Your Turn Coffee Shop Products Think about the coffee shop in your area. Identify items the coffee shop sells that would be classified as revenues. Remember, revenues for the coffee shop are related to its primary purpose: selling coffee and related items. Or, better yet, make a trip to the local coffee shop and get a first-hand experience. Solution Many coffee shops earn revenue through multiple revenue streams, including coffee and other specialty drinks, food items, gift cards, and merchandise. Expenses An expense 2 is a cost associated with providing goods or services to customers. In our opening example, the expenses that Chris incurred totaled $1,150 (consisting of $100 for brakes, $50 for fuel, and $1,000 for insurance). You might think of expenses as the opposite of revenue in that expenses reduce Chris’s checking account balance. Likewise, expenses decrease the value of the business and represent the dollar value of costs incurred to provide goods and services to customers for a given period of time. 2 Expenses are formally defined by the FASB as “outflows or other using up of assets or incurrences of liabilities (or a combination of both) from delivering or producing goods, rendering services, or carrying out other activities that constitute the entity’s ongoing major or central operations” (SFAC No. 6, p. 23). Your Turn Coffee Shop Expenses While thinking about or visiting the coffee shop in your area, look around (or visualize) and identify items or activities that are the expenses of the coffee shop. Remember, expenses for the coffee shop are related to resources consumed while generating revenue from selling coffee and related items. Do not forget about any expenses that might not be so obvious—as a general rule, every activity in a business has an associated cost. Solution Costs of the coffee shop that might be readily observed would include rent; wages for the employees; and the cost of the coffee, pastries, and other items/merchandise that may be sold. In addition, costs such as utilities, equipment, and cleaning or other supplies might also be readily observable. More obscure costs of the coffee shop would include insurance, regulatory costs such as health department licensing, point-of-sale/credit card costs, advertising, donations, and payroll costs such as workers’ compensation, unemployment, and so on. Gains A gain 3 can result from selling ancillary business items for more than the items are worth. (Ancillary business items are those that are used to support business operations.) To illustrate the concept of a gain, let’s return to our example. However, this example and the accompanying losses example are not going to be part of our income statement, balance sheet, or owner’s equity statement discussions. The gains and losses examples are only to be used in demonstrating the concepts of gains and losses. Assume that Chris paid $1,500 for a small piece of property to use for building a storage facility for her company. Further assume that Chris has an opportunity to sell the land for $2,000. She subsequently found a better storage option and decided to sell the property. After doing so, Chris will have a gain of $500 (a selling price of $2,000 and a cost of $1,500) and will also have $2,000 to deposit into her checking account, which would increase the balance. 3 FASB notes that gains represent an increase in organizational value from activities that are “ incidental or peripheral ” (SFAC No. 6, p. 24) to the primary purpose of the business. Thinking back to the proceeds ($1,400) Chris received from her landscaping business, we might ask the question: how are gains similar to and different from revenues? The revenue of $1,400 that Chris earned from her business and the $2,000 she received from selling the land are similar in that both increase her checking account balance and make her business more valuable. A difference, however, is evident if we consider how these funds were earned. Chris earned the $1,400 because she provided services (her labor) to her clients. Chris’s primary objective is to earn revenue by working for her clients. In addition, earning money by selling her land was an infrequent event for Chris, since her primary job was serving as a landscaper. Her primary goal is to earn fees or revenue, not to earn money by selling land. In fact, she cannot consider doing that again because she does not have additional land to sell. The primary goal of a business is to earn revenue by providing goods and services to customers in exchange for cash at that time or in the future. While selling other items for more than the value of the item does occur in business, these transactions are classified as gains, because these sales are infrequent and not the primary purpose of the business. Losses A loss 4 results from selling ancillary business items for less than the items are worth. To illustrate, let’s now assume that Chris sells her land that she purchased for $1,500 at a sales price of $1,200. In this case she would realize (incur) a loss of $300 on the sale of the property ($1,200 sales price minus the $1,500 cost of purchasing the property) and will also have $1,200 to deposit into her checking account, which would increase the balance. 4 FASB notes losses represent a decrease in organizational value from activities that are “ incidental or peripheral ” (SFAC No. 6, p. 24) to the primary purpose of the business. You should not be confused by the fact that the checking account balance increased even though this transaction resulted in a financial loss. Chris received $1,200 that she can deposit into her checking account and use for future expenses. The $300 loss simply indicates that she received less for the land than she paid for it. These are two aspects of the same transaction that communicate different things, and it is important to understand the differences. As we saw when comparing gains and revenues, losses are similar to expenses in that both losses and expenses decrease the value of the organization. In addition, just as Chris’s primary goal is to earn money from her job rather than selling land, in business, losses refer to infrequent transactions involving ancillary items of the business. Net Income (Net Loss) Net income (net loss) is determined by comparing revenues and expenses. Net income is a result of revenues (inflows) being greater than expenses (outflows). A net loss occurs when expenses (outflows) are greater than revenues (inflows). In accounting it is common to present net income in the following format: Recall that revenue is the value of goods and services a business provides to its customers and increase the value of the business. Expenses, on the other hand, are the costs of providing the goods and services and decrease the value of the business. When revenues exceed expenses, companies have net income. This means the business has been successful at earning revenues, containing expenses, or a combination of both. If, on the other hand, expenses exceed revenues, companies experience a net loss. This means the business was unsuccessful in earning adequate revenues, sufficiently containing expenses, or a combination of both. While businesses work hard to avoid net loss situations, it is not uncommon for a company to sustain a net loss from time-to-time. It is difficult, however, for businesses to remain viable while experiencing net losses over the long term. Shown as a formula, the net income (loss) function is: To be complete, we must also consider the impact of gains and losses. While gains and losses are infrequent in a business, it is not uncommon that a business would present a gain and/or loss in its financial statements. Recall that gains are similar to revenue and losses are similar to expenses. Therefore, the traditional accounting format would be: Shown as a formula, the net income (loss) function, including gains and losses, is: When assessing a company’s net income, it is important to understand the source of the net income. Businesses strive to attain “high-quality” net income (earnings). High-quality earnings are based on sustainable earnings—also called permanent earnings—while relying less on infrequent earnings—also called temporary earnings. Recall that revenues represent the ongoing value of goods and services the business provides (sells) to its customers, while gains are infrequent and involve items ancillary to the primary purpose of the business. We should use caution if a business attains a significant portion of its net income as a result of gains, rather than revenues. Likewise, net losses derived as a result of losses should be put into the proper perspective due to the infrequent nature of losses. While net losses are undesirable for any reason, net losses that result from expenses related to ongoing operations, rather than losses that are infrequent, are more concerning for the business. Statement of Owner’s Equity Equity is a term that is often confusing but is a concept with which you are probably already familiar. In short, equity is the value of an item that remains after considering what is owed for that item. The following example may help illustrate the concept of equity. When thinking about the concept of equity, it is often helpful to think about an example many families are familiar with: purchasing a home. Suppose a family purchases a home worth $200,000. After making a down payment of $25,000, they secure a bank loan to pay the remaining $175,000. What is the value of the family’s equity in the home? If you answered $25,000, you are correct. At the time of the purchase, the family owns a home worth $200,000 (an asset), but they owe $175,000 (a liability), so the equity or net worth in the home is $25,000. The statement of owner’s equity , which is the second financial statement created by accountants, is a statement that shows how the equity (or value) of the organization has changed over time. Similar to the income statement, the statement of owner’s equity is for a specific period of time, typically one year. Recall that another way to think about equity is net worth, or value. So, the statement of owner’s equity is a financial statement that shows how the net worth, or value, of the business has changed for a given period of time. The elements of the financial statements shown on the statement of owner’s equity include investments by owners as well as distributions to owners . Investments by owners and distributions to owners are two activities that impact the value of the organization (increase and decrease, respectively). In addition, net income or net loss affects the value of the organization (net income increases the value of the organization, and net loss decreases it). Net income (or net loss) is also shown on the statement of owner’s equity; this is an example of how the statements are interrelated. Note that the word owner’s (singular for a sole owner) changes to owners’ (plural, for a group of owners) when preparing this statement for an entity with multiple owners versus a sole proprietorship. In our example, to make it less complicated, we started with the first month of operations for Chris’s Landscaping. In the first month of operations, the owner’s equity total begins the month of August 2020, at $0, since there have been no transactions. During the month, the business received revenue of $1,400 and incurred expenses of $1,150, for net income of $250. Since Chris did not contribute any investment or make any withdrawals, other than the $1,150 for expenses, the ending balance in the owner’s equity account on August 31, 2020, would be $250, the net income earned. At this stage, it’s important to point out that we are working with a sole proprietorship to help simplify the examples. We have addressed the owner’s value in the firm as capital or owner’s equity . However, later we switch the structure of the business to a corporation, and instead of owner’s equity we begin using stockholder’s equity, which includes account titles such as common stock and retained earnings to represent the owners’ interests. The corporate treatment is more complicated because corporations may have a few owners up to potentially thousands of owners (stockholders). More detail on this issue is provided in Define, Explain, and Provide Examples of Current and Noncurrent Assets, Current and Noncurrent Liabilities, Equity, Revenues, and Expenses . Investments by Owners Generally, there are two ways by which organizations become more valuable: profitable operations (when revenues exceed expenses) and investments by owners. Organizations often have long-term goals or projects that are very expensive (for example, building a new manufacturing facility or purchasing another company). While having profitable operations is a viable way to “fund” these goals and projects, organizations often want to undertake these projects in a quicker time frame. Selling ownership is one way to quickly obtain the funding necessary for these goals. Investments by owners represent an exchange of cash or other assets for which the investor is given an ownership interest in the organization. This is a mutually beneficial arrangement: the organization gets the funding it needs on a timely basis, and the investor gets an ownership interest in the organization. When organizations generate funding by selling ownership, the ownership interest usually takes the form of common stock , which is the corporation’s primary class of stock issued, with each share representing a partial claim to ownership or a share of the company’s business. When the organization issues common stock for the first time, it is called an initial public offering (IPO) . In Corporation Accounting , you learn more about the specifics of this type of accounting. Once a company issues (or sells) common stock after an IPO, we describe the company as a publicly traded company , which simply means the company’s stock can be purchased by the general public on a public exchange like the New York Stock Exchange (NYSE). That is, investors can become owners of the particular company. Companies that issue publicly traded common shares in the United States are regulated by the Securities and Exchange Commission (SEC) , a federal regulatory agency that, among other responsibilities, is charged with oversight of financial investments such as common stock. Concepts In Practice Roku Goes Public On September 1, 2017, Roku, Inc. filed a Form S-1 with the Securities and Exchange Commission (SEC). 5 In this form, Roku disclosed its intention to become a publicly traded company, meaning its stock will trade (sell) on public stock exchanges, allowing individual and institutional investors an opportunity to own a portion (shares) of the company. The Form S-1 included detailed financial and nonfinancial information about the company. The information from Roku also included the purpose of the offering as well as the intended uses of the funds. Here is a portion of the disclosure: “The principal purposes of this offering are to increase our capitalization and financial flexibility and create a public market for our Class A common stock. We intend to use the net proceeds we receive from this offering primarily for general corporate purposes, including working capital . . . research and development, business development, sales and marketing activities and capital expenditures.” 6 5 Roku, Inc. “Form S-1 Filing with the Securities and Exchange Commission.” September 1, 2017. https://www.sec.gov/Archives/edgar/data/1428439/000119312517275689/d403225ds1.htm 6 Roku, Inc. “Form S-1 Filing with the Securities and Exchange Commission.” September 1, 2017. https://www.sec.gov/Archives/edgar/data/1428439/000119312517275689/d403225ds1.htm On September 28, 2017, Roku “went public” and exceeded expectations. Prior to the IPO, Roku estimated it would sell between $12 and $14 per share, raising over $117 million for the company. The closing price per share on September 28 was $23.50, nearly doubling initial expectations for the share value. 7 7 Roku, Inc. Data. https://finance.yahoo.com/quote/ROKU/history?p=ROKU Distributions to Owners There are basically two ways in which organizations become less valuable in terms of owners’ equity: from unprofitable operations (when expenses or losses exceed revenues or gains) and by distributions to owners. Owners (investors) of an organization want to see their investment appreciate (gain) in value. Over time, owners of common stock can see the value of the stock increase in value—the share price increases—due to the success of the organization. Organizations may also make distributions to owners , which are periodic rewards issued to the owners in the form of cash or other assets. Distributions to owners represent some of the value (equity) of the organization. For investors who hold common stock in the organization, these periodic payments or distributions to owners are called dividends . For sole proprietorships, distributions to owners are withdrawals or drawings. From the organization’s perspective, dividends represent a portion of the net worth (equity) of the organization that is returned to owners as a reward for their investment. While issuing dividends does, in fact, reduce the organization’s assets, some argue that paying dividends increases the organization’s long-term value by making the stock more desirable. (Note that this topic falls under the category of “dividend policy” and there is a significant stream of research addressing this.) Balance Sheet Once the statement of owner’s equity is completed, accountants typically complete the balance sheet , a statement that lists what the organization owns ( assets ), what it owes ( liabilities ), and what it is worth ( equity ) on a specific date . Notice the change in timing of the report. The income statement and statement of owner’s equity report the financial performance and equity change for a period of time. The balance sheet, however, lists the financial position at the close of business on a specific date. (Refer to Figure 2.2 for the balance sheet as of August 31, 2020, for Chris’ Landscaping.) Assets If you recall our previous example involving Chris and her newly established landscaping business, you are probably already familiar with the term asset 8 —these are resources used to generate revenue. In Chris’s business, to keep the example relatively simple, the business ended the month with one asset, cash, assuming that the insurance was for one month’s coverage. 8 The FASB defines assets as “probable future economic benefits obtained or controlled by a particular entity as a result of past transactions or events” (SFAC No. 6, p. 12). However, as organizations become more complex, they often have dozens or more types of assets. An asset can be categorized as a short-term asset or current asset (which is typically used up, sold, or converted to cash in one year or less) or as a long-term asset or noncurrent asset (which is not expected to be converted into cash or used up within one year). Long-term assets are often used in the production of products and services. Examples of short-term assets that businesses own include cash, accounts receivable, and inventory, while examples of long-term assets include land, machinery, office furniture, buildings, and vehicles. Several of the chapters that you will study are dedicated to an in-depth coverage of the special characteristics of selected assets. Examples include Merchandising Transactions , which are typically short term, and Long-Term Assets , which are typically long term. An asset can also be categorized as a tangible asset or an intangible asset. Tangible assets have a physical nature, such as trucks or many inventory items, while intangible assets have value but often lack a physical existence or corpus, such as insurance policies or trademarks. Liabilities You are also probably already familiar with the term liability 9 —these are amounts owed to others (called creditors). A liability can also be categorized as a short-term liability (or current liability ) or a long-term liability (or noncurrent liability ), similar to the treatment accorded assets. Short-term liabilities are typically expected to be paid within one year or less, while long-term liabilities are typically expected to be due for payment more than one year past the current balance sheet date. 9 The FASB defines liabilities as “probable future sacrifices of economic benefits arising from present obligations of a particular entity to transfer assets or provide services to other entities in the future as a result of past transactions or events” (SFAC No. 6, p. 13). Common short-term liabilities or amounts owed by businesses include amounts owed for items purchased on credit (also called accounts payable ), taxes, wages, and other business costs that will be paid in the future. Long-term liabilities can include such liabilities as long-term notes payable, mortgages payable, or bonds payable. Equity In the Statement of Owner’s Equity discussion, you learned that equity (or net assets ) refers to book value or net worth. In our example, Chris’s Landscaping, we determined that Chris had $250 worth of equity in her company at the end of the first month (see Figure 2.2 ). At any point in time it is important for stakeholders to know the financial position of a business. Stated differently, it is important for employees, managers, and other interested parties to understand what a business owns, owes, and is worth at any given point. This provides stakeholders with valuable financial information to make decisions related to the business. Statement of Cash Flows The fourth and final financial statement prepared is the statement of cash flows , which is a statement that lists the cash inflows and cash outflows for the business for a period of time. At first glance, this may seem like a redundant financial statement. We know the income statement also reports the inflows and outflows for the business for a period of time. In addition, the statement of owner’s equity and the balance sheet help to show the other activities, such as investments by and distributions to owners that are not included in the income statement. To understand why the statement of cash flows is necessary, we must first understand the two bases of accounting used to prepare the financial statements. The changes in cash within this statement are often referred to as sources and uses of cash. A source of cash lets one see where cash is coming from. For example, is cash being generated from sales to customers, or is the cash a result of an advance in a large loan. Use of cash looks at what cash is being used for. Is cash being used to make an interest payment on a loan, or is cash being used to purchase a large piece of machinery that will expand business capacity? The two bases of accounting are the cash basis and the accrual basis, briefly introduced in Describe the Income Statement, Statement of Owner’s Equity, Balance Sheet, and Statement of Cash Flows, and How They Interrelate . Under cash basis accounting , transactions (i.e., a sale or a purchase) are not recorded in the financial statements until there is an exchange of cash. This type of accounting is permitted for nonprofit entities and small businesses that elect to use this type of accounting. Under accrual basis accounting , transactions are generally recorded in the financial statement when the transactions occur, and not when paid, although in some situations the two events could happen on the same day. An example of the two methods (cash versus accrual accounting) would probably help clarify their differences. Assume that a mechanic performs a tune-up on a client’s car on May 29, and the customer picks up her car and pays the mechanic $100 on June 2. If the mechanic were using the cash method, the revenue would be recognized on June 2, the date of payment, and any expenses would be recognized when paid. If the accrual method were used, the mechanic would recognize the revenue and any related expenses on May 29, the day the work was completed. The accrual method will be the basis for your studies here (except for our coverage of the cash flow statement in Statement of Cash Flows ). The accrual method is also discussed in greater detail in Explain the Steps within the Accounting Cycle through the Unadjusted Trial Balance . While the cash basis of accounting is suited well and is more efficient for small businesses and certain types of businesses, such as farming, and those without inventory, like lawyers and doctors, the accrual basis of accounting is theoretically preferable to the cash basis of accounting. Accrual accounting is advantageous because it distinguishes between the timing of the transactions (when goods and services are provided) and when the cash involved in the transactions is exchanged (which can be a significant amount of time after the initial transaction). This allows accountants to provide, in a timely manner, relevant and complete information to stakeholders. The Adjustment Process explores several common techniques involved in accrual accounting. Two brief examples may help illustrate the difference between cash accounting and accrual accounting. Assume that a business sells $200 worth of merchandise. In some businesses, there are two ways the customers pay: cash and credit (also referred to as “on account”). Cash sales include checks and credit cards and are paid at the time of the sale. Credit sales (not to be confused with credit card sales) allow the customer to take the merchandise but pay within a specified period of time, usually up to forty-five days. A cash sale would be recorded in the financial statements under both the cash basis and accrual basis of accounting. It makes sense because the customer received the merchandise and paid the business at the same time. It is considered two events that occur simultaneously (exchange of merchandise for cash). Similar to the previous example for the mechanic, a credit sale, however, would be treated differently under each of these types of accounting. Under the cash basis of accounting, a credit sale would not be recorded in the financial statements until the cash is received, under terms stipulated by the seller. For example, assume on April 1 a landscaping business provides $500 worth of services to one of its customers. The sale is made on account, with the payment due forty-five days later. Under the cash basis of accounting, the revenue would not be recorded until May 16, when the cash was received. Under the accrual basis of accounting, this sale would be recorded in the financial statements at the time the services were provided, April 1. The reason the sale would be recorded is, under accrual accounting, the business reports that it provided $500 worth of services to its customer. The fact the customers will pay later is viewed as a separate transaction under accrual accounting ( Figure 2.3 ). Let’s now explore the difference between the cash basis and accrual basis of accounting using an expense. Assume a business purchases $160 worth of printing supplies from a supplier (vendor). Similar to a sale, a purchase of merchandise can be paid for at the time of sale using cash (also a check or credit card) or at a later date (on account). A purchase paid with cash at the time of the sale would be recorded in the financial statements under both cash basis and accrual basis of accounting. It makes sense because the business received the printing supplies from the supplier and paid the supplier at the same time. It is considered two events that occur simultaneously (exchange of merchandise for cash). If the purchase was made on account (also called a credit purchase ), however, the transaction would be recorded differently under each of these types of accounting. Under the cash basis of accounting, the $160 purchase on account would not be recorded in the financial statements until the cash is paid, as stipulated by the seller’s terms. For example, if the printing supplies were received on July 17 and the payment terms were fifteen days, no transaction would be recorded until August 1, when the goods were paid for. Under the accrual basis of accounting, this purchase would be recorded in the financial statements at the time the business received the printing supplies from the supplier (July 17). The reason the purchase would be recorded is that the business reports that it bought $160 worth of printing supplies from its vendors. The fact the business will pay later is viewed as a separate issue under accrual accounting. Table 2.2 summarizes these examples under the different bases of accounting. Transactions by Cash Basis versus Accrual Basis of Accounting Transaction Under Cash Basis Accounting Under Accrual Basis Accounting $200 sale for cash Recorded in financial statements at time of sale Recorded in financial statements at time of sale $200 sale on account Not recorded in financial statements until cash is received Recorded in financial statements at time of sale $160 purchase for cash Recorded in financial statements at time of purchase Recorded in financial statements at time of purchase $160 purchase on account Not recorded in financial statements until cash is paid Recorded in financial statements at time of purchase Table 2.2 Businesses often sell items for cash as well as on account, where payment terms are extended for a period of time (for example, thirty to forty-five days). Likewise, businesses often purchase items from suppliers (also called vendors) for cash or, more likely, on account. Under the cash basis of accounting, these transactions would not be recorded until the cash is exchanged. In contrast, under accrual accounting the transactions are recorded when the transaction occurs, regardless of when the cash is received or paid. Knowing the difference between the cash basis and accrual basis of accounting is necessary to understand the need for the statement of cash flows. Stakeholders need to know the financial performance (as measured by the income statement—that is, net income or net loss) and financial position (as measured by the balance sheet—that is, assets, liabilities, and owners’ equity) of the business. This information is provided in the income statement, statement of owner’s equity, and balance sheet. However, since these financial statements are prepared using accrual accounting, stakeholders do not have a clear picture of the business’s cash activities. The statement of cash flows solves this inadequacy by specifically focusing on the cash inflows and cash outflows. 2.2 Define, Explain, and Provide Examples of Current and Noncurrent Assets, Current and Noncurrent Liabilities, Equity, Revenues, and Expenses In addition to what you’ve already learned about assets and liabilities, and their potential categories, there are a couple of other points to understand about assets. Plus, given the importance of these concepts, it helps to have an additional review of the material. To help clarify these points, we return to our coffee shop example and now think of the coffee shop’s assets—items the coffee shop owns or controls. Review the list of assets you created for the local coffee shop. Did you happen to notice many of the items on your list have one thing in common: the items will be used over a long period of time? In accounting, we classify assets based on whether or not the asset will be used or consumed within a certain period of time, generally one year. If the asset will be used or consumed in one year or less, we classify the asset as a current asset . If the asset will be used or consumed over more than one year, we classify the asset as a noncurrent asset . Another thing you might have recognized when reviewing your list of coffee shop assets is that all of the items were something you could touch or move, each of which is known as a tangible asset. However, as you also learned in Describe the Income Statement, Statement of Owner’s Equity, Balance Sheet, and Statement of Cash Flows, and How They Interrelate , not all assets are tangible. An asset could be an intangible asset, meaning the item lacks physical substance—it cannot be touched or moved. Take a moment to think about your favorite type of shoe or a popular type of farm tractor. Would you be able to recognize the maker of that shoe or the tractor by simply seeing the logo? Chances are you would. These are examples of intangible assets, trademarks to be precise. A trademark has value to the organization that created (or purchased) the trademark, and the trademark is something the organization controls—others cannot use the trademark without permission. Similar to the accounting for assets, liabilities are classified based on the time frame in which the liabilities are expected to be settled. A liability that will be settled in one year or less (generally) is classified as a current liability , while a liability that is expected to be settled in more than one year is classified as a noncurrent liability . Examples of current assets include accounts receivable , which is the outstanding customer debt on a credit sale; inventory , which is the value of products to be sold or items to be converted into sellable products; and sometimes a notes receivable , which is the value of amounts loaned that will be received in the future with interest, assuming that it will be paid within a year. Examples of current liabilities include accounts payable , which is the value of goods or services purchased that will be paid for at a later date, and notes payable , which is the value of amounts borrowed (usually not inventory purchases) that will be paid in the future with interest. Examples of noncurrent assets include notes receivable (notice notes receivable can be either current or noncurrent), land, buildings, equipment, and vehicles. An example of a noncurrent liability is notes payable (notice notes payable can be either current or noncurrent). Why Does Current versus Noncurrent Matter? At this point, let’s take a break and explore why the distinction between current and noncurrent assets and liabilities matters. It is a good question because, on the surface, it does not seem to be important to make such a distinction. After all, assets are things owned or controlled by the organization, and liabilities are amounts owed by the organization; listing those amounts in the financial statements provides valuable information to stakeholders. But we have to dig a little deeper and remind ourselves that stakeholders are using this information to make decisions. Providing the amounts of the assets and liabilities answers the “what” question for stakeholders (that is, it tells stakeholders the value of assets), but it does not answer the “when” question for stakeholders. For example, knowing that an organization has $1,000,000 worth of assets is valuable information, but knowing that $250,000 of those assets are current and will be used or consumed within one year is more valuable to stakeholders. Likewise, it is helpful to know the company owes $750,000 worth of liabilities, but knowing that $125,000 of those liabilities will be paid within one year is even more valuable. In short, the timing of events is of particular interest to stakeholders. Think It Through Borrowing When money is borrowed by an individual or family from a bank or other lending institution, the loan is considered a personal or consumer loan. Typically, payments on these types of loans begin shortly after the funds are borrowed. Student loans are a special type of consumer borrowing that has a different structure for repayment of the debt. If you are not familiar with the special repayment arrangement for student loans, do a brief internet search to find out when student loan payments are expected to begin. Now, assume a college student has two loans—one for a car and one for a student loan. Assume the person gets the flu, misses a week of work at his campus job, and does not get paid for the absence. Which loan would the person be most concerned about paying? Why? Equity and Legal Structure Recall that equity can also be referred to as net worth—the value of the organization. The concept of equity does not change depending on the legal structure of the business (sole proprietorship, partnership, and corporation). The terminology does, however, change slightly based on the type of entity. For example, investments by owners are considered “capital” transactions for sole proprietorships and partnerships but are considered “common stock” transactions for corporations. Likewise, distributions to owners are considered “drawing” transactions for sole proprietorships and partnerships but are considered “dividend” transactions for corporations. As another example, in sole proprietorships and partnerships, the final amount of net income or net loss for the business becomes “Owner(s), Capital.” In a corporation, net income or net loss for the business becomes retained earnings , which is the cumulative, undistributed net income or net loss, less dividends paid for the business since its inception. The essence of these transactions remains the same: organizations become more valuable when owners make investments in the business and the businesses earn a profit (net income), and organizations become less valuable when owners receive distributions (dividends) from the organization and the businesses incur a loss (net loss). Because accountants are providing information to stakeholders, it is important for accountants to fully understand the specific terminology associated with the various legal structures of organizations. The Accounting Equation Recall the simple example of a home loan discussed in Describe the Income Statement, Statement of Owner’s Equity, Balance Sheet, and Statement of Cash Flows, and How They Interrelate . In that example, we assumed a family purchased a home valued at $200,000 and made a down payment of $25,000 while financing the remaining balance with a $175,000 bank loan. This example demonstrates one of the most important concepts in the study of accounting: the accounting equation , which is: In our example, the accounting equation would look like this: $200,000 = $175,000 + $25,000 $200,000 = $175,000 + $25,000 As you continue your accounting studies and you consider the different major types of business entities available (sole proprietorships, partnerships, and corporations), there is another important concept for you to remember. This concept is that no matter which of the entity options that you choose, the accounting process for all of them will be predicated on the accounting equation. It may be helpful to think of the accounting equation from a “sources and claims” perspective. Under this approach, the assets (items owned by the organization) were obtained by incurring liabilities or were provided by owners. Stated differently, every asset has a claim against it—by creditors and/or owners. Your Turn The Accounting Equation On a sheet of paper, use three columns to create your own accounting equation. In the first column, list all of the things you own (assets). In the second column, list any amounts owed (liabilities). In the third column, using the accounting equation, calculate, you guessed it, the net amount of the asset (equity). When finished, total the columns to determine your net worth. Hint: do not forget to subtract the liability from the value of the asset. Here is something else to consider: is it possible to have negative equity? It sure is . . . ask any college student who has taken out loans. At first glance there is no asset directly associated with the amount of the loan. But is that, in fact, the case? You might ask yourself why make an investment in a college education—what is the benefit (asset) to going to college? The answer lies in the difference in lifetime earnings with a college degree versus without a college degree. This is influenced by many things, including the supply and demand of jobs and employees. It is also influenced by the earnings for the type of college degree pursued. (Where do you think accounting ranks?) Solution Answers will vary but may include vehicles, clothing, electronics (include cell phones and computer/gaming systems, and sports equipment). They may also include money owed on these assets, most likely vehicles and perhaps cell phones. In the case of a student loan, there may be a liability with no corresponding asset (yet). Responses should be able to evaluate the benefit of investing in college is the wage differential between earnings with and without a college degree. Expanding the Accounting Equation Let’s continue our exploration of the accounting equation, focusing on the equity component, in particular. Recall that we defined equity as the net worth of an organization. It is helpful to also think of net worth as the value of the organization. Recall, too, that revenues (inflows as a result of providing goods and services) increase the value of the organization. So, every dollar of revenue an organization generates increases the overall value of the organization. Likewise, expenses (outflows as a result of generating revenue) decrease the value of the organization. So, each dollar of expenses an organization incurs decreases the overall value of the organization. The same approach can be taken with the other elements of the financial statements: Gains increase the value (equity) of the organization. Losses decrease the value (equity) of the organization. Investments by owners increase the value (equity) of the organization. Distributions to owners decrease the value (equity) of the organization. Changes in assets and liabilities can either increase or decrease the value (equity) of the organization depending on the net result of the transaction. A graphical representation of this concept is shown in Figure 2.4 . The format of this illustration is also intended to introduce you to a concept you will learn more about in your study of accounting. Notice each account subcategory (Current Assets and Noncurrent Assets, for example) has an “increase” side and a “decrease” side. These are called T-accounts and will be used to analyze transactions, which is the beginning of the accounting process. See Analyzing and Recording Transactions for a more comprehensive discussion of analyzing transactions and T-Accounts. Not All Transactions Affect Equity As you continue to develop your understanding of accounting, you will encounter many types of transactions involving different elements of the financial statements. The previous examples highlighted elements that change the equity of an organization. Not all transactions, however, ultimately impact equity. For example, the following do not impact the equity or net worth of the organization: 10 10 SFAC No. 6, p. 20. Exchanges of assets for assets Exchanges of liabilities for liabilities Acquisitions of assets by incurring liabilities Settlements of liabilities by transferring assets It is important to understand the inseparable connection between the elements of the financial statements and the possible impact on organizational equity (value). We explore this connection in greater detail as we return to the financial statements. 2.3 Prepare an Income Statement, Statement of Owner’s Equity, and Balance Sheet One of the key factors for success for those beginning the study of accounting is to understand how the elements of the financial statements relate to each of the financial statements. That is, once the transactions are categorized into the elements, knowing what to do next is vital. This is the beginning of the process to create the financial statements. It is important to note that financial statements are discussed in the order in which the statements are presented. Elements of the Financial Statements When thinking of the relationship between the elements and the financial statements, we might think of a baking analogy: the elements represent the ingredients, and the financial statements represent the finished product. As with baking a cake (see Figure 2.5 ), knowing the ingredients (elements) and how each ingredient relates to the final product (financial statements) is vital to the study of accounting. To help accountants prepare and users better understand financial statements, the profession has outlined what is referred to as elements of the financial statements , which are those categories or accounts that accountants use to record transactions and prepare financial statements. There are ten elements of the financial statements, and we have already discussed most of them. Revenue— value of goods and services the organization sold or provided. Expenses— costs of providing the goods or services for which the organization earns revenue. Gains— gains are similar to revenue but relate to “incidental or peripheral” activities of the organization. Losses— losses are similar to expenses but related to “incidental or peripheral” activities of the organization. Assets— items the organization owns, controls, or has a claim to. Liabilities— amounts the organization owes to others (also called creditors). Equity— the net worth (or net assets) of the organization. Investment by owners— cash or other assets provided to the organization in exchange for an ownership interest. Distribution to owners— cash, other assets, or ownership interest (equity) provided to owners. Comprehensive income — defined as the “change in equity of a business enterprise during a period from transactions and other events and circumstances from nonowner sources” (SFAC No. 6, p. 21). While further discussion of comprehensive income is reserved for intermediate and advanced studies in accounting, it is worth noting that comprehensive income has four components, focusing on activities related to foreign currency, derivatives, investments, and pensions. Financial Statements for a Sample Company Now it is time to bake the cake (i.e., prepare the financial statements). We have all of the ingredients (elements of the financial statements) ready, so let’s now return to the financial statements themselves. Let’s use as an example a fictitious company named Cheesy Chuck’s Classic Corn. This company is a small retail store that makes and sells a variety of gourmet popcorn treats. It is an exciting time because the store opened in the current month, June. Assume that as part of your summer job with Cheesy Chuck’s, the owner—you guessed it, Chuck—has asked you to take over for a former employee who graduated college and will be taking an accounting job in New York City. In addition to your duties involving making and selling popcorn at Cheesy Chuck’s, part of your responsibility will be doing the accounting for the business. The owner, Chuck, heard that you are studying accounting and could really use the help, because he spends most of his time developing new popcorn flavors. The former employee has done a nice job of keeping track of the accounting records, so you can focus on your first task of creating the June financial statements, which Chuck is eager to see. Figure 2.6 shows the financial information (as of June 30) for Cheesy Chuck’s. We should note that we are oversimplifying some of the things in this example. First, the amounts in the accounting records were given. We did not explain how the amounts would be derived. This process is explained starting in Analyzing and Recording Transactions . Second, we are ignoring the timing of certain cash flows such as hiring, purchases, and other startup costs. In reality, businesses must invest cash to prepare the store, train employees, and obtain the equipment and inventory necessary to open. These costs will precede the selling of goods and services. In the example to follow, for instance, we use Lease payments of $24,000, which represents lease payments for the building ($20,000) and equipment ($4,000). In practice, when companies lease items, the accountants must determine, based on accounting rules, whether or not the business “owns” the item. If it is determined the business “owns” the building or equipment, the item is listed on the balance sheet at the original cost. Accountants also take into account the building or equipment’s value when the item is worn out. The difference in these two values (the original cost and the ending value) will be allocated over a relevant period of time. As an example, assume a business purchased equipment for $18,000 and the equipment will be worth $2,000 after four years, giving an estimated decline in value (due to usage) of $16,000 ($18,000 − $2,000). The business will allocate $4,000 of the equipment cost over each of the four years ($18,000 minus $2,000 over four years). This is called depreciation and is one of the topics that is covered in Long-Term Assets . Also, the Equipment with a value of $12,500 in the financial information provided was purchased at the end of the first accounting period. It is an asset that will be depreciated in the future, but no depreciation expense is allocated in our example. Income Statement Let’s prepare the income statement so we can inform how Cheesy Chuck’s performed for the month of June (remember, an income statement is for a period of time ). Our first step is to determine the value of goods and services that the organization sold or provided for a given period of time. These are the inflows to the business, and because the inflows relate to the primary purpose of the business (making and selling popcorn), we classify those items as Revenues, Sales, or Fees Earned. For this example, we use Revenue. The revenue for Cheesy Chuck’s for the month of June is $85,000. Next, we need to show the total expenses for Cheesy Chuck’s. Because Cheesy Chuck’s tracks different types of expenses, we need to add the amounts to calculate total expenses. If you added correctly, you get total expenses for the month of June of $79,200. The final step to create the income statement is to determine the amount of net income or net loss for Cheesy Chuck’s. Since revenues ($85,000) are greater than expenses ($79,200), Cheesy Chuck’s has a net income of $5,800 for the month of June. Figure 2.7 displays the June income statement for Cheesy Chuck’s Classic Corn. Financial statements are created using numerous standard conventions or practices. The standard conventions provide consistency and help assure financial statement users the information is presented in a similar manner, regardless of the organization issuing the financial statement. Let’s look at the standard conventions shown in the Cheesy Chuck’s income statement: The heading of the income statement includes three lines. The first line lists the business name. The middle line indicates the financial statement that is being presented. The last line indicates the time frame of the financial statement. Do not forget the income statement is for a period of time (the month of June in our example). There are three columns. Going from left to right, the first column is the category heading or account. The second column is used when there are numerous accounts in a particular category (Expenses, in our example). The third column is a total column. In this illustration, it is the column where subtotals are listed and net income is determined (subtracting Expenses from Revenues). Subtotals are indicated by a single underline, while totals are indicated by a double underline. Notice the amount of Miscellaneous Expense ($300) is formatted with a single underline to indicate that a subtotal will follow. Similarly, the amount of “Net Income” ($5,800) is formatted with a double underline to indicate that it is the final value/total of the financial statement. There are no gains or losses for Cheesy Chuck’s. Gains and losses are not unusual transactions for businesses, but gains and losses may be infrequent for some, especially small, businesses. Concepts In Practice McDonald’s For the year ended December 31, 2016, McDonald’s had sales of $24.6 billion. 11 The amount of sales is often used by the business as the starting point for planning the next year. No doubt, there are a lot of people involved in the planning for a business the size of McDonald’s . Two key people at McDonald’s are the purchasing manager and the sales manager (although they might have different titles). Let’s look at how McDonald’s 2016 sales amount might be used by each of these individuals. In each case, do not forget that McDonald’s is a global company. 11 McDonald’s Corporation. U.S. Securities and Exchange Commission 10-K Filing. March 1, 2017. http://d18rn0p25nwr6d.cloudfront.net/CIK-0000063908/62200c2b-da82-4364-be92-79ed454e3b88.pdf A purchasing manager at McDonald’s , for example, is responsible for finding suppliers, negotiating costs, arranging for delivery, and many other functions necessary to have the ingredients ready for the stores to prepare the food for their customers. Expecting that McDonald’s will have over $24 billion of sales during 2017, how many eggs do you think the purchasing manager at McDonald’s would need to purchase for the year? According to the McDonald’s website, the company uses over two billion eggs a year. 12 Take a moment to list the details that would have to be coordinated in order to purchase and deliver over two billion eggs to the many McDonald’s restaurants around the world. 12 McDonald’s. “Our Food. Your Questions. Breakfast.” n.d. https://www.mcdonalds.com/us/en-us/about-our-food/our-food-your-questions/breakfast.html A sales manager is responsible for establishing and attaining sales goals within the company. Assume that McDonald’s 2017 sales are expected to exceed the amount of sales in 2016. What conclusions would you make based on this information? What do you think might be influencing these amounts? What factors do you think would be important to the sales manager in deciding what action, if any, to take? Now assume that McDonald’s 2017 sales are expected to be below the 2016 sales level. What conclusions would you make based on this information? What do you think might be influencing these amounts? What factors do you think would be important to the sales manager in deciding what action, if any, to take? Statement of Owner’s Equity Let’s create the statement of owner’s equity for Cheesy Chuck’s for the month of June. Since Cheesy Chuck’s is a brand-new business, there is no beginning balance of Owner’s Equity. The first items to account for are the increases in value/equity, which are investments by owners and net income. As you look at the accounting information you were provided, you recognize the amount invested by the owner, Chuck, was $12,500. Next, we account for the increase in value as a result of net income, which was determined in the income statement to be $5,800. Next, we determine if there were any activities that decreased the value of the business. More specifically, we are accounting for the value of distributions to the owners and net loss, if any. It is important to note that an organization will have either net income or net loss for the period, but not both. Also, small businesses in particular may have periods where there are no investments by, or distributions to, the owner(s). For the month of June, Chuck withdrew $1,450 from the business. This is a good time to recall the terminology used by accountants based on the legal structure of the particular business. Since the account was titled “Drawings by Owner” and because Chuck is the only owner, we can assume this is a sole proprietorship. If the business was structured as a corporation, this activity would be called something like “Dividends Paid to Owners.” At this stage, remember that since we are working with a sole proprietorship to help simplify the examples, we have addressed the owner’s value in the firm as capital or owner’s equity . However, later we switch the structure of the business to a corporation, and instead of owner’s equity, we begin using such account titles as common stock and retained earnings to represent the owner’s interests. The corporate treatment is more complicated, because corporations may have a few owners up to potentially thousands of owners (stockholders). The details of accounting for the interests of corporations are covered in Corporation Accounting . So how much did the value of Cheesy Chuck’s change during the month of June? You are correct if you answered $16,850. Since this is a brand-new store, the beginning value of the business is zero. During the month, the owner invested $12,500 and the business had profitable operations (net income) of $5,800. Also, during the month the owner withdrew $1,450, resulting in a net change (and ending balance) to owner’s equity of $16,850. Shown in a formula: Beginning Balance + Investments by Owners ± Net Income (Net Loss) – Distributions, or $0 + $12,500 + $5,800 – $1,450 = $16,850 $0 + $12,500 + $5,800 – $1,450 = $16,850 Figure 2.8 shows what the statement of owner’s equity for Cheesy Chuck’s Classic Corn would look like. Notice the following about the statement of owner’s equity for Cheesy Chuck’s: The format is similar to the format of the income statement (three lines for the heading, three columns). The statement follows a chronological order, starting with the first day of the month, accounting for the changes that occurred throughout the month, and ending with the final day of the month. The statement uses the final number from the financial statement previously completed. In this case, the statement of owner’s equity uses the net income (or net loss) amount from the income statement (Net Income, $5,800). Balance Sheet Let’s create a balance sheet for Cheesy Chuck’s for June 30. To begin, we look at the accounting records and determine what assets the business owns and the value of each. Cheesy Chuck’s has two assets: Cash ($6,200) and Equipment ($12,500). Adding the amount of assets gives a total asset value of $18,700. As discussed previously, the equipment that was recently purchased will be depreciated in the future, beginning with the next accounting period. Next, we determine the amount of money that Cheesy Chuck’s owes (liabilities). There are also two liabilities for Cheesy Chuck’s. The first account listed in the records is Accounts Payable for $650. Accounts Payable is the amount that Cheesy Chuck’s must pay in the future to vendors (also called suppliers) for the ingredients to make the gourmet popcorn. The other liability is Wages Payable for $1,200. This is the amount that Cheesy Chuck’s must pay in the future to employees for work that has been performed. Adding the two amounts gives us total liabilities of $1,850. (Here’s a hint as you develop your understanding of accounting: Liabilities often include the word “payable.” So, when you see “payable” in the account title, know these are amounts owed in the future—liabilities.) Finally, we determine the amount of equity the owner, Cheesy Chuck, has in the business. The amount of owner’s equity was determined on the statement of owner’s equity in the previous step ($16,850). Can you think of another way to confirm the amount of owner’s equity? Recall that equity is also called net assets (assets minus liabilities). If you take the total assets of Cheesy Chuck’s of $18,700 and subtract the total liabilities of $1,850, you get owner’s equity of $16,850. Using the basic accounting equation, the balance sheet for Cheesy Chuck’s as of June 30 is shown in Figure 2.9 . Connecting the Income Statement and the Balance Sheet Another way to think of the connection between the income statement and balance sheet (which is aided by the statement of owner’s equity) is by using a sports analogy. The income statement summarizes the financial performance of the business for a given period of time. The income statement reports how the business performed financially each month—the firm earned either net income or net loss. This is similar to the outcome of a particular game—the team either won or lost. The balance sheet summarizes the financial position of the business on a given date. Meaning, because of the financial performance over the past twelve months, for example, this is the financial position of the business as of December 31. Think of the balance sheet as being similar to a team’s overall win/loss record—to a certain extent a team’s strength can be perceived by its win/loss record. However, because different companies have different sizes, you do not necessarily want to compare the balance sheets of two different companies. For example, you would not want to compare a local retail store with Walmart. In most cases you want to compare a company with its past balance sheet information. Statement of Cash Flows In Describe the Income Statement, Statement of Owner’s Equity, Balance Sheet, and Statement of Cash Flows, and How They Interrelate , we discussed the function of and the basic characteristics of the statement of cash flows. This fourth and final financial statement lists the cash inflows and cash outflows for the business for a period of time . It was created to fill in some informational gaps that existed in the other three statements (income statement, owner’s equity/retained earnings statement, and the balance sheet). A full demonstration of the creation of the statement of cash flows is presented in Statement of Cash Flows . Creating Financial Statements: A Summary In this example using a fictitious company, Cheesy Chuck’s, we began with the account balances and demonstrated how to prepare the financial statements for the month of June, the first month of operations for the business. It will be helpful to revisit the process by summarizing the information we started with and how that information was used to create the four financial statements: income statement, statement of owner’s equity, balance sheet, and statement of cash flows. We started with the account balances shown in Figure 2.10 . The next step was to create the income statement, which shows the financial performance of the business. The income statement is shown in Figure 2.11 . Next, we created the statement of owner’s equity, shown in Figure 2.12 . The statement of owner’s equity demonstrates how the equity (or net worth) of the business changed for the month of June. Do not forget that the Net Income (or Net Loss) is carried forward to the statement of owner’s equity. The third financial statement created is the balance sheet, which shows the company’s financial position on a given date. Cheesy Chuck’s balance sheet is shown in Figure 2.13 . Think It Through Financial Statement Analysis In Why It Matters , we pointed out that accounting information from the financial statements can be useful to business owners. The financial statements provide feedback to the owners regarding the financial performance and financial position of the business, helping the owners to make decisions about the business. Using the June financial statements, analyze Cheesy Chuck’s and prepare a brief presentation. Consider this from the perspective of the owner, Chuck. Describe the financial performance of and financial position of the business. What areas of the business would you want to analyze further to get additional information? What changes would you consider making to the business, if any, and why or why not? Ethical Considerations Financial Statement Manipulation at Waste Management Inc. Accountants have an ethical duty to accurately report the financial results of their company and to ensure that the company’s annual reports communicate relevant information to stakeholders. If accountants and company management fail to do so, they may incur heavy penalties. For example, in 2002 the Securities and Exchange Commission (SEC) charged the top management of Waste Management, Inc. with inflating profits by $1.7 billion to meet earnings targets in the period 1992–1997. An SEC press release alleged “that defendants fraudulently manipulated the company’s financial results to meet predetermined earnings targets. . . . They employed a multitude of improper accounting practices to achieve this objective.” 13 The defendants in the case manipulated reports to defer or eliminate expenses, which fraudulently inflated their earnings. Because they failed to accurately report the financial results of their company, the top accountants and management of Waste Management, Inc. face charges. 13 U.S. Securities and Exchange Commission. “Waste Management Founder, Five Other Former Top Officers Sued for Massive Fraud.” March 26, 2002. https://www.sec.gov/news/headlines/wastemgmt6.htm Thomas C. Newkirk, the associate director of the SEC’s Division of Enforcement, stated, “For years, these defendants cooked the books, enriched themselves, preserved their jobs, and duped unsuspecting shareholders” 14 The defendants, who included members of the company board and executives, benefited personally from their fraud in the millions of dollars through performance-based bonuses, charitable giving, and sale of company stock. The company’s accounting form, Arthur Andersen , abetted the fraud by identifying the improper practices but doing little to stop them. 14 U.S. Securities and Exchange Commission. “Waste Management Founder, Five Other Former Top Officers Sued for Massive Fraud.” March 26, 2002. https://www.sec.gov/news/headlines/wastemgmt6.htm Liquidity Ratios In addition to reviewing the financial statements in order to make decisions, owners and other stakeholders may also utilize financial ratios to assess the financial health of the organization. While a more in-depth discussion of financial ratios occurs in Appendix A: Financial Statement Analysis , here we introduce liquidity ratios , a common, easy, and useful way to analyze the financial statements. Liquidity refers to the business’s ability to convert assets into cash in order to meet short-term cash needs. Examples of the most liquid assets include accounts receivable and inventory for merchandising or manufacturing businesses. The reason these are among the most liquid assets is that these assets will be turned into cash more quickly than land or buildings, for example. Accounts receivable represents goods or services that have already been sold and will typically be paid/collected within thirty to forty-five days. Inventory is less liquid than accounts receivable because the product must first be sold before it generates cash (either through a cash sale or sale on account). Inventory is, however, more liquid than land or buildings because, under most circumstances, it is easier and quicker for a business to find someone to purchase its goods than it is to find a buyer for land or buildings. Working Capital The starting point for understanding liquidity ratios is to define working capital —current assets minus current liabilities. Recall that current assets and current liabilities are amounts generally settled in one year or less. Working capital (current assets minus current liabilities) is used to assess the dollar amount of assets a business has available to meet its short-term liabilities. A positive working capital amount is desirable and indicates the business has sufficient current assets to meet short-term obligations (liabilities) and still has financial flexibility. A negative amount is undesirable and indicates the business should pay particular attention to the composition of the current assets (that is, how liquid the current assets are) and to the timing of the current liabilities. It is unlikely that all of the current liabilities will be due at the same time, but the amount of working capital gives stakeholders of both small and large businesses an indication of the firm’s ability to meet its short-term obligations. One limitation of working capital is that it is a dollar amount, which can be misleading because business sizes vary. Recall from the discussion on materiality that $1,000, for example, is more material to a small business (like an independent local movie theater) than it is to a large business (like a movie theater chain). Using percentages or ratios allows financial statement users to more easily compare small and large businesses. Current Ratio The current ratio is closely related to working capital; it represents the current assets divided by current liabilities. The current ratio utilizes the same amounts as working capital (current assets and current liabilities) but presents the amount in ratio, rather than dollar, form. That is, the current ratio is defined as current assets/current liabilities. The interpretation of the current ratio is similar to working capital. A ratio of greater than one indicates that the firm has the ability to meet short-term obligations with a buffer, while a ratio of less than one indicates that the firm should pay close attention to the composition of its current assets as well as the timing of the current liabilities. Sample Working Capital and Current Ratio Calculations Assume that Chuck, the owner of Cheesy Chuck’s, wants to assess the liquidity of the business. Figure 2.14 shows the June 30, 2018, balance sheet. Assume the Equipment listed on the balance sheet is a noncurrent asset. This is a reasonable assumption as this is the first month of operation and the equipment is expected to last several years. We also assume the Accounts Payable and Wages Payable will be paid within one year and are, therefore, classified as current liabilities. Working capital is calculated as current assets minus current liabilities. Cheesy Chuck’s has only two assets, and one of the assets, Equipment, is a noncurrent asset, so the value of current assets is the cash amount of $6,200. The working capital of Cheesy Chuck’s is $6,200 – $1,850 or $4,350. Since this amount is over $0 (it is well over $0 in this case), Chuck is confident he has nothing to worry about regarding the liquidity of his business. Let’s further assume that Chuck, while attending a popcorn conference for store owners, has a conversation with the owner of a much larger popcorn store—Captain Caramel’s. The owner of Captain Caramel’s happens to share the working capital for his store is $52,500. At first Chuck feels his business is not doing so well. But then he realizes that Captain Caramel’s is located in a much bigger city (with more customers) and has been around for many years, which has allowed them to build a solid business, which Chuck aspires to do. How would Chuck compare the liquidity of his new business, opened just one month, with the liquidity of a larger and more-established business in another market? The answer is by calculating the current ratio, which removes the size differences (materiality) of the two businesses. The current ratio is calculated as current assets/current liabilities. We use the same amounts that we used in the working capital calculation, but this time we divide the amounts rather than subtract the amounts. So Cheesy Chuck’s current ratio is $6,200 (current assets)/$1,850 (current liabilities), or 3.35. This means that for every dollar of current liabilities, Cheesy Chuck’s has $3.35 of current assets. Chuck is pleased with the ratio but does not know how this compares to another popcorn store, so he asked his new friend from Captain Caramel’s. The owner of Captain Caramel’s shares that his store has a current ratio of 4.25. While it is still better than Cheesy Chuck’s, Chuck is encouraged to learn that his store is performing at a more competitive level than he previously thought by comparing the dollar amounts of working capital. IFRS Connection IFRS and US GAAP in Financial Statements Understanding the elements that make up financial statements, the organization of those elements within the financial statements, and what information each statement relays is important, whether analyzing the financial statements of a US company or one from Honduras. Since most US companies apply generally accepted accounting principles (GAAP) 15 as prescribed by the Financial Accounting Standards Board (FASB), and most international companies apply some version of the International Financial Reporting Standards (IFRS), 16 knowing how these two sets of accounting standards are similar or different regarding the elements of the financial statements will facilitate analysis and decision-making. 15 Publicly traded companies in the United States must file their financial statements with the SEC, and those statements must be compiled using US GAAP. However, in some states, private companies can apply IFRS for SMEs (small and medium entities). 16 The following site identifies which countries require IFRS, which use a modified version of IFRS, and which countries prohibit the use of IFRS. https://www.iasplus.com/en/resources/ifrs-topics/use-of-ifrs Both IFRS and US GAAP have the same elements as components of financial statements: assets, liabilities, equity, income, and expenses. Equity, income, and expenses have similar subcategorization between the two types of GAAP (US GAAP and IFRS) as described. For example, income can be in the form of earned income (a lawyer providing legal services) or in the form of gains (interest earned on an investment account). The definition of each of these elements is similar between IFRS and US GAAP, but there are some differences that can influence the value of the account or the placement of the account on the financial statements. Many of these differences are discussed in detail later in this course when that element—for example, the nuances of accounting for liabilities—is discussed. Here is an example to illustrate how these minor differences in definition can impact placement within the financial statements when using US GAAP versus IFRS. ACME Car Rental Company typically rents its cars for a time of two years or 60,000 miles. At the end of whichever of these two measures occurs first, the cars are sold. Under both US GAAP and IFRS, the cars are noncurrent assets during the period when they are rented. Once the cars are being “held for sale,” under IFRS rules, the cars become current assets. However, under US GAAP, there is no specific rule as to where to list those “held for sale” cars; thus, they could still list the cars as noncurrent assets. As you learn more about the analysis of companies and financial information, this difference in placement on the financial statements will become more meaningful. At this point, simply know that financial analysis can include ratios, which is the comparison of two numbers, and thus any time you change the denominator or the numerator, the ratio result will change. There are many similarities and some differences in the actual presentation of the various financial statements, but these are discussed in The Adjustment Process at which point these similarities and differences will be more meaningful and easier to follow.
business_ethics
Summary 9.1 Entrepreneurship and Start-Up Culture The atmosphere surrounding entrepreneurs and their start-ups can provide a dizzying rush. The opportunities to create a company, be your own boss, make a dramatic impact on business, establish an entrepreneurial culture that will be adopted by others, and possibly become rich in the process certainly all appeal to our human nature. Still, the entrepreneurial lifestyle is challenging, and the success rate for start-ups is exceptionally low. Interpersonal conflicts are prevalent in start-up environments, and entrepreneurs who seek to stay true to their vision and ethical values face a difficult road. At many points, start-up founders have to choose how they most wish to be remembered: for the sake of their business success alone or also for the ethical fashion in which they attained that success and the humane culture they have embedded in their new firm. Sometimes these are mutually exclusive goals, but the most ethical entrepreneurs do their best to ensure that both objectives mesh for themselves and their firms. This lies at the heart of any definition of ethical leadership. 9.2 The Influence of Advertising The Internet and social media present new canvasses for marketing that possess great power and for which rules and ethical norms are being developed. Psychological appeals and subliminal messaging present their own ethical issues. Discerning consumers currently must rely on their own sensibility to ferret out factual claims for advertised products and bear the burden of shielding those under their charge from the worst manipulative effects of marketing. 9.3 The Insurance Industry Business owners and individuals are willing to pay insurance premiums in the hope that they will never have to be file a claim for reimbursement on their policy. Because the insurance industry profits only when claims are few and small, there may be a bigger role for government to play in managing disaster insurance through a private/public partnership, such as FEMA currently does to provide flood insurance and the California Earthquake Authority does where potentially disastrous earthquakes may occur. Ethical issues such whether to expand the use of public tax revenues to subsidize these partnerships need to be resolved. 9.4 Ethical Issues in the Provision of Health Care The United States, unlike countries in Europe, has little tradition of merging the efforts of the state or federal government with that of private employers in the provision of health care. Although the quality of U.S. health care has rarely been challenged, its limited accessibility has posed ethical quandaries for business because many employees necessarily look to their employers for this benefit. The 2010 Affordable Care Act is an ambitious effort to meet the need for health care for all. Individual states have considered, and sometimes enacted, programs of their own to supply universal health care.
Chapter Outline 9.1 Entrepreneurship and Start-Up Culture 9.2 The Influence of Advertising 9.3 The Insurance Industry 9.4 Ethical Issues in the Provision of Health Care Introduction As consumers, employees, and community members, we see everywhere the extent to which business can contribute to either social well-being or harm. Some career paths invite special scrutiny because of their influential role in society and the extent to which they serve as magnets for business students. Friends and critics of these professions have studied the unique ethical issues they raise and individuals who pursue careers in these fields should give careful consideration to these findings to decide if the benefits outweigh the potential downsides. Entrepreneurship, for instance, offers the opportunity to construct your own business in the hope of profit, but at some personal and financial cost. Are the potential gains being overplayed when, in fact, most entrepreneurial businesses fail? Advertising is the driver of sales, but are its claims honest and its delivery platforms, including social media, acting in good faith? Do they exert undue or biased influence on the gullible and the young? Insurance is necessary, but what is the proper and ethical role of property insurers, for example, in the face of increasingly dangerous natural disasters? Health care in the United States is extraordinarily expensive, especially compared with that in other industrialized nations, and access is too often limited to those with means. Should quality health care be a right for all rather than a privilege for the few?
[ { "answer": { "ans_choice": 2, "ans_text": "C" }, "bloom": null, "hl_context": "<hl> A fairly common characteristic of successful start-ups is charismatic , driven founders with take-no-prisoner competitive mentalities , as was illustrated earlier in this chapter in the example of Kalanick and the leadership values at Uber . <hl> After all , it takes a thick skin and powerful ego to get through the inevitable disappointments that confront a start-up leader . Often , however , even when these self-assured personalities evade the most egregious behavior of a Kalanick , they still remain very difficult for others to abide . Many companies discover that a different leadership ethos is necessary as they grow . Could entrepreneurs still succeed if they also embraced a humanistic leadership style at the outset , or would this invariably undermine the already low initial odds of success ? It is a difficult problem with which many firms wrestle . Dedicated employees may be put off by demanding leaders who are harsh , giving little back to loyal workers even after achieving success . New employees may decide the working climate is less congenial than they anticipated and simply leave . This turnstile effect of workers voting on management with their feet constitutes an ethical judgment of repugnant leadership at the top .", "hl_sentences": "A fairly common characteristic of successful start-ups is charismatic , driven founders with take-no-prisoner competitive mentalities , as was illustrated earlier in this chapter in the example of Kalanick and the leadership values at Uber .", "question": { "cloze_format": "The characteristic that is common to most entrepreneurs is ___.", "normal_format": "What characteristic is common to most entrepreneurs?", "question_choices": [ "an advanced degree", "deep management experience", "a driven, highly competitive nature", "a large network of business contacts" ], "question_id": "fs-idm348969840", "question_text": "What characteristic is common to most entrepreneurs?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 1, "ans_text": "B" }, "bloom": null, "hl_context": "Newer staff , however , may not share this mindset . They may simply be seeking a secure position with a growing business rather than a chance to get in on the ground floor of a risky start-up . They will not necessarily have the tolerance for the demanding hours , chaos , and abrasive personalities that can characterize the early days of an enterprise . <hl> Can entrepreneurial founders shape a company ’ s culture so it can accommodate talented employees who are looking for a corporate culture that supports some work – life balance ? <hl>", "hl_sentences": "Can entrepreneurial founders shape a company ’ s culture so it can accommodate talented employees who are looking for a corporate culture that supports some work – life balance ?", "question": { "cloze_format": "Corporate culture comes from ________.", "normal_format": "Where does corporate culture come from?", "question_choices": [ "the commitment of the company’s employees", "the founder’s idea of what the work environment should be like", "government regulations about labor relations", "the nature of the company’s product or service" ], "question_id": "fs-idm365525264", "question_text": "Corporate culture comes from ________." }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 0, "ans_text": "A" }, "bloom": null, "hl_context": "Even if a start-up becomes what its founders wish it to be — astronomically successful — inevitably it will change as it grows , acquires new locations , and hires more employees . <hl> These changes may eventually produce an organization with added layers — essentially , a hardened bureaucracy that slows down and complicates the management process . <hl> The company may no longer make essential decisions with the speed and nimbleness that once were possible . <hl> In short , success for a start-up is often accompanied by the risk of becoming , over time , exactly the traditional business structure its founders once rejected . <hl> So the founders of an entrepreneurial shop , and their successors , must guard against change that radically alters the original spirit of innovation and the free and rapid flow of information , even as the company grows . <hl> No business leader seeks bureaucracy , but it typically accompanies growth within any organization . <hl>", "hl_sentences": "These changes may eventually produce an organization with added layers — essentially , a hardened bureaucracy that slows down and complicates the management process . In short , success for a start-up is often accompanied by the risk of becoming , over time , exactly the traditional business structure its founders once rejected . No business leader seeks bureaucracy , but it typically accompanies growth within any organization .", "question": { "cloze_format": "One danger a growing start-up can face is ________.", "normal_format": "What is one danger a growing start-up can face?", "question_choices": [ "encroaching bureaucracy", "lack of good employees", "legal issues", "venture capitalists" ], "question_id": "fs-idm367370736", "question_text": "One danger a growing start-up can face is ________." }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 0, "ans_text": "A" }, "bloom": null, "hl_context": "Psychological appeals form the basis of the most successful ads . <hl> Going beyond the standard ad pitch about the product ’ s advantages , psychological appeal s try to reach our self-esteem and persuade us that we will feel better about ourselves if we use certain products . <hl> If advertising frames the purchase of a popular toy as the act of a loving parent rather than an extravagance , for instance , consumers may buy it not because their child needs it but because it makes them feel good about what generous parents they are . This is how psychological appeals become successful , and when they do work , this often constitutes a victory for the power of psychological persuasion at the expense of ethical truthfulness .", "hl_sentences": "Going beyond the standard ad pitch about the product ’ s advantages , psychological appeal s try to reach our self-esteem and persuade us that we will feel better about ourselves if we use certain products .", "question": { "cloze_format": "Psychological appeals succeed when they ________.", "normal_format": "When do sychological appeals succeed?", "question_choices": [ "make consumers feel better about themselves", "let consumers compare themselves to their peers", "show consumers how to save money", "introduce new products" ], "question_id": "fs-idm302963728", "question_text": "Psychological appeals succeed when they ________." }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 0, "ans_text": "A" }, "bloom": null, "hl_context": "Within the multipayer system , many U . S . workers have traditionally looked to their employers or their unions to subsidize the cost of care and thereby make it available for them and their families . Many reasons explain why this is so . <hl> In contrast to the European and Canadian perspective , for example , in which both the state and employers are presumed to have an interest in and responsibility for underwriting the cost of health care , the traditional U . S . approach is that workers and their employers should be responsible for securing this coverage . <hl> This belief reflects an unease on the part of some about assigning services to the government , because this implies the need for a larger governing entity as well as additional taxes to sustain it . The sentiment also reflects a conviction on the part of some that self-reliance is always to be preferred when securing the necessities of life .", "hl_sentences": "In contrast to the European and Canadian perspective , for example , in which both the state and employers are presumed to have an interest in and responsibility for underwriting the cost of health care , the traditional U . S . approach is that workers and their employers should be responsible for securing this coverage .", "question": { "cloze_format": "In the European tradition, the main responsibility for supplying workers with health care lies with the group of ___ .", "normal_format": "In the European tradition, the main responsibility for supplying workers with health care lies with which of these groups?", "question_choices": [ "the government and labor unions", "labor unions", "nonprofit agencies and private companies", "individual workers" ], "question_id": "fs-idm495353568", "question_text": "In the European tradition, the main responsibility for supplying workers with health care lies with which of these groups?" }, "references_are_paraphrase": null } ]
9
9.1 Entrepreneurship and Start-Up Culture Learning Objectives By the end of this section, you will be able to: Identify ethical challenges relating to entrepreneurial start-ups Describe positive and negative effects of growth in a start-up Discuss the role of the founder in instilling an ethical culture An entrepreneur is a business leader willing to risk starting a new company and offering a product or service he or she hopes will be sustainable and permit the firm to prosper. The entrepreneur may have to find the money required for this venture and typically draws on business experience gained by working for others first. Entrepreneurship often requires hard work, but the potential for economic payoff and career satisfaction appeals to many. The Risks of Entrepreneurship Although the risk of failure associated with starting a business is real and even high, we hear much in the media about success stories and little about those entrepreneurs who crash and burn. Perhaps the allure of entrepreneurship inevitably outshines any mention of the downside. Still, start-ups impose a higher than normal degree of risk, and we turn to the evidence for this now. What is the specific nature of entrepreneurial risk? Different studies yield different results, but business consultant Patrick Henry reported that “75 percent of venture-backed startups fail.” Henry added that “this statistic is based on a Harvard Business School study by Shikhar Ghosh. In a study by Statistical Brain, ‘Startup Business Failure Rate by Industry,’ the failure rate of all U.S. companies after five years was over 50 percent, and over 70 percent after ten years.” 1 This figure might be enough to chill the enthusiasm of any would-be entrepreneur who believes an exciting or novel concept is enough to support a successful company with a minimal amount of time and effort and a great deal of other people’s money. Still, the ranks of start-ups expand prodigiously each month in the United States. Even start-ups that beat the odds financially need to be watchful for a different sort of pitfall, an ethical failure that can be nourished by the very strengths that allow a company to get off the ground. That pitfall is the hubris or excessive pride that may characterize some entrepreneurs, particularly after they have had some initial success. Uber, an application-based, ride-hailing service, was founded in San Francisco by Travis Kalanick and Garrett Camp in 2009. If ever an idea matched the success potential of smartphones, it was this one. Offering a cheaper and more convenient service than hailing a cab on city streets, Uber was valued at $70 billion in 2017 and operated, with varying degrees of success, in seventy countries at that point. However, the corporate culture, especially at headquarters, left many observers aghast in early 2017 after an Uber engineer, Susan Fowler, blogged about her experiences there. Other employees substantiated much of her account, revealing an atmosphere rife with misogyny, homophobia, and sexual harassment. This culture was permitted—even fostered—by Kalanick, who reigned unchecked for several years over what the New York Times labeled an “aggressive, unrestrained workplace culture.” 2 Muted grumblings from quarters within the company never received much attention outside the firm, allowing Kalanick to become a high-flying role model for would-be entrepreneurs who wished to emulate his success. A reckoning finally arrived when Uber’s board of directors asked him to resign his position as chief executive officer in June 2017. Yet the workplace culture that prevailed during his years at the company was not unique to Uber. Many firms have experienced it. Holding destructive egos in check is an ethical challenge at many successful businesses, particularly at hard-riding start-ups. Founders and their start-up teams need to be aware of how deeply their attitudes toward others; their visible treatment of employees, customers, and clients; and their display of fairness will come to shape the company they are building. It is not enough for the founders to hypothesize, “we’ll get around to establishing the right protocols after we’re solvent.” Nor is it adequate to insist that standards of courteous business practice will naturally emerge on their own. An initial culture either of ethics or its absence will set a tone from the first day of business. If the founders believe these niceties are not required of them owing to their genius or confidence, such arrogance will displace ethics as a best practice. To believe otherwise is self-deception. Why Successful Start-Ups Change as They Grow A legendary example of a start-up that still inspires many today is the Hewlett-Packard Corporation (HP). Its origins lie in the efforts of Bill Hewlett and David Packard, two Stanford University classmates in the 1930s. Much like members of a garage band, they started their company in a real garage, and the firm has outgrown its humble beginnings many times over ( Figure 9.2 ). Start-ups are exciting. Many of their founders, like the late Steve Jobs of Apple, attain near-rock star status, and the companies can generate enormous profit. They allow many to do what they have always wanted to do and be their own bosses. Yet we often overlook the fact that even some of the most successful entrepreneurs experience many failures before they succeed, and long hours of hard work are typically required even for these failures. Smart entrepreneurs learn from their failures, but each lesson can be painful, frustrating, and time consuming. A unique personality is required to weather the stresses and strains of a start-up, and it is a personality that tolerates much personal deprivation as it pursues the perceived highest goal of all, success for the firm, no matter what personal or collective costs might be entailed. The culture of entrepreneurialism allows for many business leaders and their staffs to be deprived of a portion of their humanity along the way to success. Thus, a preeminent ethical consideration is whether the result justifies this cost. At the very least, determined entrepreneurs must be advised of these possible sacrifices. They constitute the collateral damage of entrepreneurial dreams that any ambitious start-up founder should contemplate. Will one emerge at the end of the process as the sort of person one most wishes to be? Even if a start-up becomes what its founders wish it to be—astronomically successful—inevitably it will change as it grows, acquires new locations, and hires more employees. These changes may eventually produce an organization with added layers—essentially, a hardened bureaucracy that slows down and complicates the management process. The company may no longer make essential decisions with the speed and nimbleness that once were possible. In short, success for a start-up is often accompanied by the risk of becoming, over time, exactly the traditional business structure its founders once rejected. So the founders of an entrepreneurial shop, and their successors, must guard against change that radically alters the original spirit of innovation and the free and rapid flow of information, even as the company grows. No business leader seeks bureaucracy, but it typically accompanies growth within any organization. Particular problems that arise out of bureaucratization are additional layers of management, more codified procedures, and internal obstructions that surface as a business attempts to capitalize on its initial success. As more employees are added to the mix, the original team’s sense of common purpose can become diluted. Max Weber (1864–1920), the German academic, economist, and sociologist, appreciated the consequences of bureaucracy years ago. In Wirtschaft und Gesellschaft [ Economy and Society ], published posthumously in 1925, he pointed out, “in the private economy, [bureaucracy emerges] only in the most advanced institutions of capitalism.” 3 Weber cemented the link between bureaucracy and capitalism further: “The development of the money economy [emphasis is Weber’s] . . . is a presupposition of bureaucracy. Today it not only prevails but is predominant.” 4 Because start-ups constitute an “advanced” feature of capitalism, and because bureaucracy presupposes a “money economy,” Weber prophesied that agile start-ups would be ripe for bureaucratization as they grow and age. Finally, he included this acknowledgement of the permanence of bureaucracy: “Once it is firmly established, bureaucracy is among those social structures which are the hardest to destroy.” 5 More recently, Michael A. Lutzker confirmed Weber’s testimony on the inevitability of bureaucracy: “The administrative function has of course been a pervasive element of all societies, ancient, medieval, and modern, but Weber was among the first to recognize the distinctive character of bureaucracy in the modern era.” 6 Simply put, the very same success that permits a start-up to flourish often produces bureaucratic structures that chip away at the free-flowing camaraderie that allowed a handful of founders to act instantly and with one mind. As the staff expands, employees’ ranks become more defined, titles and hierarchies appear, and individual achievements become harder to spot. This is what changes within a successful start-up, and it moves the company away from the more congenial atmosphere that characterized it at its outset. An original small partnership often becomes a corporate behemoth, and it takes on many of the attributes of those cubicle workplaces that frequently inspired its founders to strike out on their own in the first place. All the better, then, if ethical practices that permit coworkers to bond as colleagues with a sense of commitment to each other and to their customers or clients emerge through a company’s trial-and-error experience at the outset. Only if the founders and initial staff emphasize treating all stakeholders with honesty, courtesy, and respect will the new firm stand a chance of indelibly cementing ethics into its operating matrix. Entrepreneurial Culture A fairly common characteristic of successful start-ups is charismatic, driven founders with take-no-prisoner competitive mentalities, as was illustrated earlier in this chapter in the example of Kalanick and the leadership values at Uber. After all, it takes a thick skin and powerful ego to get through the inevitable disappointments that confront a start-up leader. Often, however, even when these self-assured personalities evade the most egregious behavior of a Kalanick, they still remain very difficult for others to abide. Many companies discover that a different leadership ethos is necessary as they grow. Could entrepreneurs still succeed if they also embraced a humanistic leadership style at the outset, or would this invariably undermine the already low initial odds of success? It is a difficult problem with which many firms wrestle. Dedicated employees may be put off by demanding leaders who are harsh, giving little back to loyal workers even after achieving success. New employees may decide the working climate is less congenial than they anticipated and simply leave. This turnstile effect of workers voting on management with their feet constitutes an ethical judgment of repugnant leadership at the top. Link to Learning Although no single set of traits identifies the ideal start-up leader, a demanding, driven nature is a fairly common characteristic. Consider these brief profiles of entrepreneurs: first, a profile on Walt Disney and then a profile on Steve Jobs as well as this video showing a contrasting view from Kerrie Laird at Vodafone. After watching the videos, consider this thought experiment: Suppose the cult of the charismatic—but dogmatic—entrepreneurial leader such as Walt Disney or Steve Jobs were replaced with one steeped in a commitment to employee empowerment that Kerrie Laird claims for Vodafone? Could this change the culture at start-ups? If it could, do you believe that change would be for the better or worse? These observations identify what may be unique to entrepreneurial culture . This is a combination of personality and management style often identified with those business leaders who strike out on their own, bring a start-up to life, and shape its initial business practices and culture on the job. If the enterprise is successful, the principles and philosophy of the founder become enshrined in the lore of the company, so that long after his or her departure, succeeding leaders find themselves beholden to the management philosophy exemplified from the early days of the firm. 7 As you seek the right leadership style to implement on the job, begin by asking precisely what kind of leader you would prefer to work for if you were not the boss. The answer you provide may very well be the best model to follow as you develop your own leadership personality, whether it is at a start-up or a more established company. The first employees of a start-up realize what is at stake as the company tiptoes into new entrepreneurial waters. The founder may be the boss, but those associated with him or her sense a collaborative spirit that directly joins them to the founder as well as each other. There can be a genuine fraternity among those who have been with the firm since day 1 or shortly thereafter. Founding members of an entrepreneurial business are also often willing to undergo the strains and rigors attached to a start-up in return for an ownership stake in the company that allows them to profit handsomely from its later growth and success. Newer staff, however, may not share this mindset. They may simply be seeking a secure position with a growing business rather than a chance to get in on the ground floor of a risky start-up. They will not necessarily have the tolerance for the demanding hours, chaos, and abrasive personalities that can characterize the early days of an enterprise. Can entrepreneurial founders shape a company’s culture so it can accommodate talented employees who are looking for a corporate culture that supports some work–life balance? Consider also the ethical practices of an entrepreneur and the ethical expectations of employees. Suppose that one of the distinguishing features woven into the fabric of the start-up is the respect extended to customers or clients. An entrepreneur typically promises always to hold customers in the highest regard, never lie to them, and serve them well. Furthermore, suppose this entrepreneur successfully instills this same ethos among all employees from the outset. Respect for customers is intended to become a distinguishing feature of the business; even if it causes monetary loss to the company, this entrepreneur will not cheat a client or misrepresent the company’s services. Finally, presume that this ethos is embedded into the culture of the company while it is still in start-up mode. Now, and literally against the odds, suppose the company becomes successful. This may signal the hardest time of all for the entrepreneur. Growth often accompanies success, and growth means, among other things, more employees. Not all these new hires will be as committed to the same degree of responsibility for customers. They will not necessarily set out to cheat clients, but they might lack the founder’s enthusiasm for the most honorable treatment of customers. How can an entrepreneur ensure that the initial commitment carries over to the second generation of leadership? He or she cannot simply order it to happen—human nature usually does not respond so easily. So entrepreneurs must do their best to ensure that their version of customer service, one that prioritizes respect for clients, is passed along to new employees. It may be ingrained in the longest-serving employees, but it must be nurtured to the point where it has the same significance for the newest hires. This is where leadership mettle is tested to the severest degree. Cases from the Real World Growing Up with a Start-Up In the summer of 1970, a college senior named Paul Orfalea opened a store near the University of California, Santa Barbara, campus. He called it “Kinko’s” after his own nickname and, with his partners, he sold college school supplies and around-the-clock copying services for students. After twenty-five years, Kinko’s had grown to 1,200 stores and 23,000 employees, and Orfalea privately and lucratively sold it to FedEx. Over the many years that Orfalea ran his start-up, his business became amazingly profitable but also imposed enormous stress on him and his founding partners and coworkers. As he put it, “I don’t hide the fact that I have a problem with anger.” 8 Since selling the company, Orfalea has spent many years mending relationships with those who worked most closely with him while he was building it. What contributed to the tensions Orfalea felt while managing this burgeoning enterprise? Long hours, of course, but also the need he felt to sustain his initial success, to make each year more profitable than the last. Entrepreneurs often believe they are only as successful as their last quarter’s profit and are driven to exceed it. Orfalea also felt that he alone was equipped to call others to account and veto what he felt were bad business ideas. Anger became a chief enemy he battled. “In my mid- to late-forties,” he said, “I struggled increasingly to manage my own emotional nature. Sometimes I felt I’d created a monster. The monster wasn’t Kinko’s, it was me.” 9 Orfalea acknowledged the anger and resentment that he often felt toward other longtime staff at the company, which overpowered the respect that he knew he owed them. Consequently, he directed comments and actions at his colleagues that he has spent many subsequent years attempting to redress. All in all, he has labored diligently to repair friendships that he admits were frayed by his behavior alone. After reflection, Orfalea now offers these recommendations to prospective entrepreneurs: Do not give way to your anger in the midst of the frustrating turns business inevitably takes. Do not take that anger home with you, either. Finally, try to be the person you most genuinely are, both at work and at home. It took Orfalea time to learn these lessons, but they are worthwhile for any would-be entrepreneur to ponder. 10 Critical Thinking What price would you be willing to pay to pursue an entrepreneurial career? What price would you demand from your partners in the business? How long could you let work monopolize your life? In your opinion, was Orfalea right to manage Kinko’s the way he did as it grew? Were the worries, anxieties, and bad moods he experienced inevitable? How would you avoid these? 9.2 The Influence of Advertising Learning Objectives By the end of this section, you will be able to: Discuss how social media has altered the advertising landscape Explain the influence of advertising on consumers Analyze the potential for subliminal advertising The advertising industry revolves around creating commercial messages urging the purchase of new or improved products or services in a variety of media: print, online, digital, television, radio, and outdoor. Because as consumers we need and want to be informed, this feature of advertising is to the good. Yet some advertising is intended to lead to the purchase of goods and services we do not need. Some ads may make claims containing only the thinnest slice of truth or exaggerate and distort what the goods and services can actually deliver. All these tactics raise serious ethical concerns that we will consider here. The Rise of Social Media Relevant to any discussion of the influence and ethics of advertising is the emergence and dominance of social media , which now serve as the format within which many people most often encounter ads. Kelly Jensen, a digital-marketing consultant, observed that we inhabit a “Digital Era” in which “the internet is arguably the single most influential factor of our culture—transforming the way we view communication, relationships, and even ourselves. Social media platforms have evolved to symbolize the status of both individuals and businesses alike. . . Today, using social media to create brand awareness, drive revenue, engage current customers, and attract new ones isn’t optional anymore. Now it is an absolute ‘must.’” 11 These are bold claims—as are the claims of some advertising—but Jensen argues convincingly that social media platforms reach many consumers, especially younger ones, who simply cannot be captured by conventional advertising schemes. For those who derive most of the significant information that shapes their lives solely through electronic sources, nothing other than social media–based appeals stands much chance of influencing their purchasing decisions. This upending of conventional modes of advertising has begun to change the content of ads dramatically. It certainly presents a new stage on which people as young as their teens increasingly rely for help in choosing what to buy. Many marketers have come to appreciate that if they are not spreading the word about their products and services via an electronic source, many millennials will ignore it. 12 Undeniably, a digital environment for advertising, selling, and delivering products and services functions as a two-edged sword for business. It provides lightning-quick access to potential customers, but it also opens pathways for sensitive corporate and consumer data to be hacked on an alarming scale. It offers astute companies nearly unlimited capacity to brand themselves positively in the minds of purchasers, but it simultaneously offers a platform for disgruntled stakeholders to assail companies for both legitimate and self-serving reasons. Paul A. Argenti, who has taught business communication for many years at the Tuck School of Business at Dartmouth University, has studied this dilemma. As he put it, “mobile apps have created a new playground for cyber-thieves.” 13 And consumer advocates and purchasers alike “now use technology to rally together and fuel or escalate a crisis—posing additional challenges for the corporation” in the crosshairs of criticism. Finally, “the proliferation of online blogs and social networking sites has greatly increased the visibility and reach of all current events, not excluding large corporate” 14 bungling. Regardless of the delivery platform, however, any threat that the advertising of unnecessary or harmful products may pose to our autonomy as consumers is complicated by the fact that sometimes we willingly choose to buy goods or services we may not necessarily require. Sometimes we even buy things that have been proven to be harmful to us, such as cigarettes and sugary drinks. Yet we may desire these products even if we do not need them. If we have the disposable income to make these discretionary purchases, why should we not do so, and why should advertisers not advise us of their availability? Does Advertising Drive Us to Unnecessary Purchases? By definition, advertising aims to persuade consumers to buy goods and services, many of which are nonessential. Although consumers have long been encouraged to heed the warning caveat emptor (let the buyer beware), it is a valid question whether advertisers have any ethical obligation to rein in the oft-exaggerated claims of their marketing pitches. Most consumers emphatically would agree that they do. The award-winning Harvard University economist John Kenneth Galbraith directly addressed this issue in The Affluent Society , first published in 1958. In what he depicted as the “the dependence effect,” Galbraith bemoaned the power of corporations to harness wide-ranging advertising strategies, marketing efforts, and sales pitches to influence consumer purchasing decisions. 15 He asked whether it is possible for a sophisticated advertising campaign to create a demand for a product whose benefits are frivolous at best. If so, is there anything inherently wrong with that? Or are informed consumers themselves responsible for resisting tempting—though misleading—advertising claims and exercising their own best judgment about whether to buy a product that might be successful, not because it deserves to be but simply because of the marketing hype behind it? These questions remain fundamental to the manager’s task of creating ethical advertising campaigns in which truthful content is prioritized over inducing wasteful consumption. Psychological appeals form the basis of the most successful ads. Going beyond the standard ad pitch about the product’s advantages, psychological appeal s try to reach our self-esteem and persuade us that we will feel better about ourselves if we use certain products. If advertising frames the purchase of a popular toy as the act of a loving parent rather than an extravagance, for instance, consumers may buy it not because their child needs it but because it makes them feel good about what generous parents they are. This is how psychological appeals become successful, and when they do work, this often constitutes a victory for the power of psychological persuasion at the expense of ethical truthfulness. Purchases are also affected by our notion of what constitutes a necessity versus a luxury, and that perception often differs across generations. Older consumers today can probably remember when a cell phone was considered a luxury, for instance, rather than a necessity for every schoolchild. On the other hand, many younger consumers consider the purchase of a landline unnecessary, whereas some older people still use a conventional phone as their main or even preferred means of communication. The cars and suburban homes that were once considered essential purchases for every young family are slowly becoming luxuries, replaced, for many millennials, by travel. Generational differences like these are carefully studied by advertisers who are anxious to make use of psychological appeals in their campaigns. A consumer craze based on little more than novelty—or, at least, not on necessity or luxury in the conventional sense—is the Pet Rock, a recurring phenomenon that began in 1977. Pet Rocks have been purchased by the millions over the years, despite being nothing more than rocks. During the 2017 holiday shopping season, they retailed at $19.95. 16 Is this a harmless fad, or a rip-off of gullible consumers who are persuaded it can satisfy a real need? In the annals of marketing, the Pet Rock craze denotes one of the most successful campaigns—still unfolding today, though in subdued fashion—in support of so dubious a product. As long as marketers refrain from breaking the law or engaging in outright lies, are they still acting ethically in undertaking influential advertising campaigns that may drive gullible consumers to purchase products with minimal usefulness? Is this simply the free market in operation? In other words, are manufacturers just supplying a product, promoting it, and then seeing whether customers respond positively to it? Or are savvy marketing campaigns exerting too much influence on consumers ill prepared to resist them? Many people have long asked exactly these questions, and we still have arrived at no clear consensus as to how to answer them. Yet it remains an obligation of each new generation of marketers to reflect on these points and, at the very least, establish their convictions about them. A second ethical question is how we should expect reasonable people to respond to an avalanche of marketing schemes deliberately intended to separate them from their hard-earned cash. Are consumers obligated to sift through all the messages and ultimately make purchasing decisions in their own best interest? For example, does a perceived “deal” on an unhealthy food option justify the purchase ( Figure 9.3 )? These questions have no consensus answers, but they underlie any discussion of the point at which sophisticated advertising runs headlong into people’s obligation to take responsibility for the wisdom of their purchases. No one would argue that children are particularly susceptible to the ads commercial television rains over them regularly. Generally, young children have not developed sufficient judgment to know what advertised products are good for them and which ones have little or no benefit or perhaps can even harm. Research has even shown that very young children have difficulty separating what is real on television from what is not. This is especially so as it pertains to advertising for junk food. Savvy marketers take advantage of the fact that young children (those younger than age seven or eight years) view advertising in the same manner they do information from trustworthy adults—that is, as very credible—and so marketers hone pitches for junk food directly to these children. 17 What restrictions could we reasonably impose on those who gear their ads toward children? We could argue that they should take special care that ads targeting children make absolutely no exaggerated claims, because children are less capable of seeing through the usual puffery that most of us ignore. Children are more literal, and once they gain the ability to understand messages directed toward them, especially when voiced by adult authority figures, they typically accept these as truthful statements. When adults make poor consumer choices, who is responsible? Is it ourselves? Is it our society and culture, which permit the barrage of marketing to influence us in ways we often come to regret? Is it the persuasive power of marketers, which we should rein in through law? Do adults have the right to some assistance from marketers as they attempt to carry out their responsibility to protect children from manipulative ads? We have no easy answers to these questions, though they have taken on special urgency as technology has expanded the range of advertising even to our smartphones. Is Subliminal Advertising Real? It may be possible for marketing to be unfairly persuasive in ways that overwhelm the better judgment of consumers. Whether it is the consumers’ responsibility to resist or marketers’ to tone down their appeals, or both, will continue to be debated. Yet the question of where responsibility lies when consumers are steered to make choices certainly has ethical ramifications. Some psychologists and educational specialists claim that the very old and the very young are particularly ill prepared to exercise good judgment in the face of subliminal advertising , that is, embedded words or images that allegedly reach us only beneath the level of our consciousness. Other experts, however, disagree and insist that subliminal advertising is an urban myth that no current technology could create or sustain. A U.S. journalist, Vance Packard, published The Hidden Persuaders in 1957, contending that subliminal messaging had already been introduced into some U.S. cinemas to sell more refreshments at the theaters’ snack bars. Alarms sounded at the prospect, but it turned out that any data on which Packard was relying came from James Vicary, a U.S. market researcher who insisted he had engineered the feat in a cinema in New Jersey. No other substantiation was provided, and Vicary’s claim was eventually dismissed as self-promotion, which he seemed to concede in an interview five years later. Although the immediate threat of subliminal advertising receded, some people remain concerned that such persuasion might indeed be possible, especially with the advent of better technologies, like virtual reality, to implement it. 18 A 2015 study at the University of South Carolina found that thirsty test subjects placed in the role of shoppers in a simulated grocery store could be subliminally influenced in their choice of beverages if they were primed by images of various beverage brands within fifteen minutes of acknowledging being thirsty. After that window of time passed, however, any impact of subliminal messaging receded. 19 So the scientific evidence establishing any real phenomenon of subliminal advertising is inconclusive. Put another way, the evidence to this point does not definitively demonstrate the existence of a current technology making subliminal marketing pitches possible. Given this, it cannot be clearly determined whether such a technology, if it did exist, would be effective. Another question is whether virtual reality and augmented reality might eventually make subliminal advertising viable. Real subliminal persuasion might render children, the elderly, and those with developmental disabilities more vulnerable to falling prey. Could even the most skeptical viewer resist a message so powerfully enhanced that the product can be sampled without leaving home? Would you be in favor of federal government regulation to prevent such ads? What sort of ethical imperatives would you be willing to request of or impose on sophisticated marketers? Link to Learning Is subliminal messaging real? Watch this video where BBC Earth Lab investigates a bit whimsically what truth might lie in the claim that subliminal advertising is real to learn more. Advertising plays a useful role in informing consumers of new or modified products and services in the marketplace, and wise purchasers will pay attention to it but with a discerning eye. Even the exaggerated claims that often accompany ads can serve a purpose as long as we do not unquestioningly accept every pitch as true. 9.3 The Insurance Industry Learning Objectives By the end of this section, you will be able to: Discuss whether the underlying business model of the insurance industry is an ethical one Identify the reasons why the government offers certain kinds of insurance Discuss the ethical issues in insurers’ decisions whether to offer disaster insurance Explain the concept of redlining Although the concept of insurance dates back to antiquity, the insurance industry as a profession came of age in the seventeenth century, when maritime trade in valuable commodities like coffee, tea, cocoa, sugar, and silk became an immense industry, but one fraught with uncertainty. Merchants sought a means to limit their financial losses in the event their cargoes were lost at sea. In England, merchants and shippers gathered together in associations, or syndicates, to distribute the risk of loss as evenly as possible. For a fee, individual merchants and ships’ owners in these syndicates could buy insurance, essentially the right to be financially compensated by the syndicate’s fund for their loss if their shipments or vessels sank. The first such association of traders and shippers began at Samuel Lloyd’s coffee house, on Tower Street near the River Thames, in 1688. This was the origin of the huge insurance market now known as Lloyd’s of London, 20 and from these early forms of group insurance sprang the profession as it exists today. From the seventeenth century to the present, the profession has faced a fundamental ethical quandary: An insurance company makes money when purchaser fees, called premiums , are numerous and claim s , requests for monetary compensation for covered losses, are few. But the reality is that accidents occur, whether they take the form of shipping losses, vehicular collisions, or home or business fires. So insurance carriers set customer premiums at a high enough rate to compensate themselves with a baseline profit when claims for compensation arise. The ethical question then is what constitutes a reasonable profit. The way the industry defines “reasonable” is directly reflected in the premiums it sets, which also take into account actuarial and statistical calculations of the historic frequency of the occurrence of various claims. How Insurance Works The irony of insurance coverage of any sort is that we buy it hoping never to use it. Still, business and consumers alike appreciate that a catastrophic loss can be financially devastating and so they seek to protect against it. Insurance coverage does not prevent illness, accidents, or other unforeseen events from occurring, but it does offer a means to recover, at least partially, from the monetary costs associated with them. Insurance policies constitute a form of contract between insurers and the insured. To reduce their losses in those situations in which they must pay on a claim, insurers do their best to attach high premiums to the coverage and identify exclusions and limits on it. They worry about being forced to pay out on frivolous and exaggerated claims, while policyholders fear that on the rare occasions when they will have to file a claim, their reimbursement will be minuscule and/or their future premiums will rise. From the perspective of the consumer, the guarantee of a fair payout on a claim is the only inducement to pay insurance premiums in the first place. What Would You Do? Valuing Your Inventory versus Valuing Your Employees Assume you are the owner of a small apparel manufacturer with approximately fifty employees. Your business is located in a blighted area of town where the jobs you provide are important, but the insurance costs of doing business there are significant, too. Recently, fire and theft coverage has escalated in cost, but it is essential to protect your premises and inventory, and local ordinances require that you purchase it. You have customarily provided health coverage for your employees and their families, which many of them would not be able to afford if they had to bear the cost themselves. You would like to continue providing this coverage—though, due to your small employee base, you are not legally obligated to do so—but these costs have risen too. Finally, you would prefer to stay in this location, because you feel an obligation to your workers, most of whom live nearby, and because you feel welcomed by the community itself, which includes some longtime customers. Still, you may be forced to choose between paying for your employee health care costs and moving to a different area of town where fire and theft coverage would not cost as much. Critical Thinking How will you make the decision within an ethical framework? What will you, your business, and your employees gain and lose based on what you decide? What, if anything, do you and your business owe the community of which you have been a part for so long? Insurance protections are, in fact, limited. In August 2017, Hurricane Harvey dumped fifty-two inches of rain on Houston, Texas, accompanied by fierce winds. Tens of thousands of homes, stores, factories, and other industrial sites suffered severe damage and flooding. Although normal homeowners’ and business owners’ insurance provides for loss due to hurricane winds, it does not cover loss due to flooding. As The Economist observed in the immediate aftermath of the hurricane, “whereas wind damage is covered under most standard insurance policies in America, flood insurance is a government-run add-on that far from all homeowners buy. As a result, of over $30 billion in property losses in Texas, only 40 percent may be insured.” 21 Not only do few homeowners buy flood insurance; few private insurers offer it. After all, most insurance carriers are for-profit, and companies would make little money insuring everyone against flood damage in flood-prone areas. It would be a losing proposition for any carrier to undertake, because insurance companies enjoy their highest returns when claims are few and payouts small. But the federal government is not a commercial broker and does not intend to make a profit from extending any sort of insurance coverage. For that reason, the National Flood Insurance Act of 1968 established a way to dispense flood coverage through a federal agency. Today that supervising agency is the Federal Emergency Management Authority (FEMA), in partnership with the Department of Homeland Security ( Figure 9.4 ). As of August 2017, just before Harvey struck, some five million households had taken out FEMA-sponsored flood coverage. 22 Link to Learning Consumers’ criticisms of the insurance industry are not limited to the United States; they pose an international issue for the profession. Read this Sydney Morning Herald article that explores the causes of controversy that haunt insurance carriers in Australia to learn more. Principally, they center on the lengths to which insurers might go to disallow a claim and so dispose of their obligation to pay out on it, at least according to some consumer watchdogs. The California Earthquake Authority serves a similar function at the state level by managing privately funded insurance against earthquakes in California. The private brokers in the program make no profit from offering this coverage, but they do earn the right to offer (and profit from) other insurance in California. The Ethical Dilemma of Insuring against Natural Disasters We do not know with certainty what effect climate change will have on the incidence or severity of natural disasters (i.e., accidents that do not appear to have any direct human cause). We do know, however, that these events can be ruinously expensive, for the carriers that insure against them and for those who suffer them and must put their lives back together afterward. Business writer Don Jergler said, for example, that “climate change has created a ‘wildfire crisis in California,’ which in turn is ‘causing a fire insurance predicament.’” California insurance commissioner Dave Jones warned in December 2017, after a particularly disastrous fire season in California, that “insurers may start to back off writing insurance in some areas [of the state],” and this would pose a crisis for homeowners who consequently lost insurance protection against losses caused by wildfires. 23 In Canada, too, “environmental risks linked to climate change are becoming important issues for insurers who need to consider their response to related risks and climate related losses whether arising from weather related events such as flood and storms or liability risks from third party claims.” 24 When insurance carriers must pay claimholders more often on claims arising from natural disasters, they lose money at a rate that could make them less willing to underwrite similar policies in the future. This unwillingness, in turn, would deny coverage against these disasters to an increasing number of individuals and companies. The high cost of disaster claims and subsequent shrinking of policy offerings are losses first experienced by the insurance industry, but they have rapid and dire consequences for policyholders. Again, we come to the ethical conundrum as to what we might fairly expect from insurance carriers and from clients who seek to indemnify themselves against natural disasters. In regions where certain kinds of disasters are more likely to occur, is it reasonable to dictate that carriers still must provide coverage? If so, should we consider extending public subsidies to the carriers to protect them against catastrophic payouts? Should premiums be assigned on the basis of the incidence patterns and severity of risk associated with particular disasters in certain regions? With these questions, we return to the ethical consideration of what constitutes a reasonable profit for carriers and what premium policy holders ought to be charged for sufficient coverage. The United States does not have the strong tradition of private/public ownership of industries, such as petroleum extraction or air travel that some other nations do. 25 Essentially, private/public ownership is an arrangement in which private (industry) and public (government) monies are combined to more safely bear an industry’s risk and also share in its profit. It is often a successful partnership. When we consider the scale of loss that can result from natural disasters, and the extent of the public’s need for protection from such loss, insurance may be a U.S. industry in which private/public ownership of some policies would be appropriate. The National Flood Insurance Program and the California Earthquake Authority are rare examples of public agencies managing insurance coverage that private insurers have declined to provide because the potential for profit is too low. Whether partnerships like this can and should be expanded, and whether they can be funded from federal and state budgets, are ethical questions for federal and state governments and policyholders alike. Cases from the Real World What Does the Future Hold for the Insurance Industry? Many insurance carriers enjoy a robust business. As an example, UnitedHealth Group Incorporated, headquartered in Minnesota, had about $185 million in sales in 2017 and employed approximately 230,000 people. Still, as an industry report from the business research company Hoovers established, insurers of all stripes, health or auto or property or anything else, face two major hurdles. First, they “are increasingly subject to a large number of regulations and reporting requirements by states. Consequently, some insurers have withdrawn from states that impose burdensome requirements.” Second, large-scale “claims have become more common, creating problematic concentrations of risk for individual insurers. . . . And some risks can be large enough to drive insurers out of business or cause them to curtail services offered, increase rates, or leave states where risk is highest.” 26 Thus, profits can be high within the industry, but so can payouts in the aftermath of major catastrophes. The report goes on to say that “floods, hurricanes, and tornadoes” produce the riskiest economic circumstances for the industry. Consequently, states in which these weather events are more common—Alabama, Florida, and North Carolina—have seen some carriers cease business operations within them. 27 Critical Thinking In selecting coverage and setting prices, how does an insurance company choose the ethical balance between making a reasonable profit and risking catastrophic losses of its own? Should the law require that carriers offer property insurance in states where harsh natural disasters occur? Or should federal and state monies be used to subsidize insurance companies’ resources in these circumstances? In each case, why or why not? Redlining: Discrimination in Insurance A specific ethical challenge within the insurance profession is the tendency to engage in redlining . Redlining is the practice of assigning or denying coverage for certain policies, such as auto, homeowners, or business insurance, on the basis of the geographic neighborhoods where applicants for such coverage live, particularly inner-city neighborhoods. A variation on the practice is to charge considerably higher prices for the same coverage in different neighborhoods. Redlining assumes that the propensity for accidents, burglaries, fires, and other catastrophes is higher in some areas than others, so claims and costs will be higher for the insurance carrier. At first glance, this practice appears to make economic sense from the perspective of both the insurer and the insured. Looking beneath the surface, however, reveals that redlined neighborhoods are often areas where racial and ethnic minorities live. No insurance carrier ever admits to engaging in discriminatory redlining (the term refers to an older practice by which insurance companies marked certain neighborhoods in red on print copies of coverage maps). Nearly every state in the United States forbids the practice. Yet a comprehensive 2017 study by Consumer Reports and ProPublica, a nonprofit research organization, indicated the phenomenon may remain very much a reality. This study focused on rates for auto insurance and found that for “decades, auto insurers have been observed to charge higher average premiums to drivers living in predominantly minority urban neighborhoods than to drivers with similar safety records living in majority White neighborhoods. Insurers have long defended their pricing by saying that the risk of accidents is greater in those neighborhoods, even for motorists who have never had one.” 28 The authors of the report compared auto insurance premiums and claims paid in four states (California, Illinois, Missouri, and Texas) and found similar results whether the carrier was Allstate, Geico, Liberty Mutual, or another. They contended “that many of the disparities in auto insurance prices between minority and White neighborhoods are wider than differences in risk can explain.” 29 This is significant because laws do typically permit premium rates to be set according to the incidence of claims filed within certain neighborhoods. Yet laws never allow rates to be based solely or predominantly on the race or ethnicity of the residents in different neighborhoods. This is the essence of prohibited redlining. Professionals in the industry do well to steer clear of this practice or even the appearance of it, and that is the overriding theme of this study. Drawing back, the ethical challenge for any responsible carrier is to ensure that the race, ethnicity, or creed of any policyholder plays absolutely no role in the premiums assigned him or her. There is no defensible reason to base a carrier’s decision to extend or deny insurance coverage or assign the premium amount for it on these factors. 9.4 Ethical Issues in the Provision of Health Care Learning Objectives By the end of this section, you will be able to: Identify ethical problems related to the availability and cost of health care in the United States and elsewhere Discuss recent developments in insuring or otherwise providing for health care in the United States Private health care in the United States has historically been of high quality and readily available, but only for those who could afford it. This model for rationing health services is rare in the developed world and stands in dramatic contrast to the provision of health care in other industrialized economies. Those who provide health care and administer the health care system find that balancing the quality of, access to, and cost of medical care is an ethical dilemma in which they must continually engage. 30 Multipayer Health Care in the United States Typically in the United States, medical services have been dispensed through a multipayer health care system , in which the patient and others, such as an employer and a private health insurance company, all contribute to pay for the patient’s care. Germany, France, and Japan also have multipayer systems. In a single-payer health care system such as those in the United Kingdom and Canada, national tax revenues pay the largest portion of citizens’ medical care, and the government is the sole payer compensating those who provide that care. Contributions provided by employers and employees provide the rest. Both single- and multipayer systems help reduce costs for patients, employers, and insurers; both, especially single-payer, are also heavily dependent on taxes apportioned across employers and the country’s population. In a single-payer system, however, because payment for health care is coordinated and dispensed by the government, almost no one lacks access to medical services, including visitors and nonpermanent residents. Many reasons exist for the predominance of the multipayer system in the United States. Chief among these is the U.S. tradition that doctors’ services and hospital care are privatized and run for profit. The United States has no federal health care apparatus that organizes physicians, clinics, and medical centers under a single government umbrella. Along with the profit motive, the fact that providers are compensated at a higher average rate than their peers abroad ensures that health care is more expensive in the United States than in most other nations. The United States also has more health care professionals per citizen than most other countries, and more medical centers and clinics ( Figure 9.5 ). One positive result is that the wait for most elective medical procedures is often shorter than in other countries, and travel time to a nearby medical facility is often less. Still, paying for health care remains one of the most controversial topics in the United States, and many question what it is that Americans gain from the current system to balance the cost. As an exhaustive study from The Commonwealth Fund asserted, “the United States spends far more on health care than other high-income countries, with spending levels that rose continuously over the past three decades. . . . Yet the U.S. population has poorer health than other countries.” 31 Besides its inefficiencies, the state of U.S. health care raises challenging ethical issues for professionals in the field and for patients as well. What happens if many poorer people cannot afford health care? Should doctors treat them anyway? Who is qualified to receive subsidized (insured) health care? In the absence of universal health care, which is generally ensured elsewhere by a single-payer system that entitles everyone to receive care at very low cost, can the United States truly boast of being the richest nation on Earth? Put another way, when the least materially advantaged in a country do not have access to quality health care, what is the worth such a nation patently is assigning to those human beings residing within it? Supporters of the status quo for health care in the United States may point to state-of-the-art facilities as evidence of its success. Yet other nations, such as Australia, the United Kingdom, and the Netherlands, have equal levels of medical technologies available for patients and are given much more favorable marks for universal health insurance and accessibility by The Commonwealth Fund. The High Cost of Prescription Drugs Discussions of health care accessibility have become politically charged, so for now it is enough to observe that not only is medical care enormously expensive in the United States but so are prescription drugs. According to William B. Schultz, an attorney writing in the Washington Post in 2017, “in the past 35 years, the only significant victory in the battle to control drug prices has been the enactment of legislation that established the generic drug program at the FDA [Federal Drug Administration].” Otherwise, he stated, “prescription drug prices account for 17 percent of the nation’s health-care costs, up from 7 percent in the 1990s,” and “prescription drug spending accounts for nearly 20 percent of total program spending for Medicare, the largest of the governmental health-care programs.” 32 (Schultz is not entirely impartial; he is a partner in a law firm that represents generic drug providers, among other clients.) Link to Learning The New York Times asked its readers to relay their experiences as purchasers of prescribed medicines that they thought carried much too high a price tag. This article on some of the reader responses to drug prices was reported by two journalists at the paper, Katie Thomas and Charles Ornstein. The only way to recoup the enormous cost of developing new drugs, says the pharmaceutical industry, is to pass it along to consumers. Critics, on the other hand, assert that the much of the expense incurred within the industry results from the high cost of marketing new drugs. Wherever the truth lies in this debate, it remains that exorbitant prices for much-needed medicines dramatically reduce their social value when only a few individuals can actually afford to obtain them. What does it say of our priorities if we have the technology to create life-saving medicines but allow astronomic prices effectively to deny them to many patients who require them? Paying for Health Care and Wellness Within the multipayer system, many U.S. workers have traditionally looked to their employers or their unions to subsidize the cost of care and thereby make it available for them and their families. Many reasons explain why this is so. In contrast to the European and Canadian perspective, for example, in which both the state and employers are presumed to have an interest in and responsibility for underwriting the cost of health care, the traditional U.S. approach is that workers and their employers should be responsible for securing this coverage. This belief reflects an unease on the part of some about assigning services to the government, because this implies the need for a larger governing entity as well as additional taxes to sustain it. The sentiment also reflects a conviction on the part of some that self-reliance is always to be preferred when securing the necessities of life. John E. Murray, a professor of economics at the University of Toledo, offered a related explanation. He cited the existence of industrial sickness funds in the United States, which arose in the late nineteenth and early twentieth centuries. These were monies “organized by workers through their employer or union [that] provided the rudiments of health insurance, principally consisting of paid sick leave, to a large minority of the industrial workforce of the late nineteenth and early twentieth centuries.” 33 Murray stated that these funds declined in popularity not because they were ineptly administered or rendered bankrupt by World War I or the Great Depression but rather because they gave way to even more effective instruments in the form of group insurance policies offered by employers or labor unions. So the U.S. worker’s experience differed from that of European labor in that much significant health care coverage was provided under the auspices of unions and employers rather than the state. Murray noted another source of relief for workers who experienced illness or injury that prevented them from working for any period of time, and that was charity. 34 Specific versions of charity were offered by religious organizations, including Christian churches and Jewish synagogues. Often, these religious bodies banded together to provide monetary benefits for sick or injured members of their own faith who might otherwise have been denied health coverage due to prejudice. 35 The U.S. social experience featured more ethnic and cultural diversity, especially in the nineteenth and early twentieth centuries, than was present in many European nations, and a downside is the racial, ethnic, and religious prejudice it inspired. A final distinction Murray pointed to is the past opposition of the American Medical Association to any sort of state-sponsored insurance. Early supporters of industrial sickness funds, including some physicians, anticipated that most doctors would support these funds as pathways ultimately directed to state-provided coverage. Instead, in 1920, “the American Medical Association voted officially to state its opposition to government health insurance. A sociologist concluded that from this time to the 1960s, physicians were the loudest opponents of government insurance.” 36 By default, then, many U.S. workers came to rely more on their employers or unions than on any other source for coverage. However, this explanation does not answer the larger ethical question of who should provide health insurance to residents and citizens, a question that continues to roil politics and society in the nation even today. Physicians and other healthcare professionals in the United States have always been held to high ethical standards in terms of the care they provide their patients. In fact, the American Medical Association first proposed a code of medical ethics in 1847, its founding year. Since then, the AMA has continued to revisit precisely what constitutes medical ethics for its members. In 2008, its code of medical ethics was revised. 37 The revisions imply that education in medical ethics for healthcare professionals is not accomplished once and for all. Rather, retraining and recertification is an ongoing process. More recently, large corporations have moved from providing one-size-fits-all insurance plans to compiling a menu of offerings to accommodate the different needs of their employees. Workers with dependent children may opt for maximum health care coverage for their children. Employees without dependents or a partner may elect a plan without this coverage and thereby pay lower premiums (the initial cost for coverage). Yet others might minimize their health-insurance coverage and convert some of the employer costs that are freed up into added pension or retirement plan value. Employers and workers have become creative in tailoring benefit plans that best suit the needs of employees ( Figure 9.6 ). Some standard features of such plans are the copayment , a set fee per service paid by the patient and typically negotiated between the insurance carrier and the employer; the annual deductible , a preset minimum cost for health care for which the patient is responsible each year before the carrier will assume subsequent costs; and percent totals for certain medical or dental procedures that patients must pay before the carrier picks up the remainder. Despite the intricacies of this customization, employers have found the group coverage policies they offer to be expensive for them too, more so with each passing year. Full health care coverage is becoming rarer as a standard employment benefit, and it is often available only to those who work full time. California, for example, stipulates that most workers need not be provided with employer health care coverage unless they work at least twenty hours a week. Rising costs for both employers and employees have combined to leave fewer employees with health care benefits at any given time. Employees with limited or no coverage for themselves and their dependents often cope by cutting back on the medical attention they seek, even when doing so places their health at risk. Whenever workers must skip medical services due to cost considerations, this places both them and their employers in an ethical quandary, because both typically want workers to be in good health. Furthermore, when employees must deny their dependents appropriate health care, this dilemma is all the more intensified. To try to reduce the costs to themselves of employee health care insurance coverage, some companies have instituted wellness programs to try to ensure that their workforces are as healthy as possible. Some popular wellness program offerings are measures to help smokers quit, workout rooms on work premises or subsidized gym memberships, and revamped vending and cafeteria offerings that provide a range of healthier choices. Some companies even offer employees bonuses or other rewards for quitting smoking or achieving specific fitness goals such as weight loss or miles walked per week. Such employer efforts appear benign at first glance, because these measures truly can produce better health on the part of workers. Still, ethical questions arise as to who the true beneficiaries of such policies are. Is it the employees themselves or the companies for which they work? Furthermore, if such measures were to become compulsory rather than optional, would it still reflect managerial benevolence toward employees? We discuss this in the following paragraphs. Wellness programs were inspired by safety programs first created by U.S. manufacturers in the 1960s. These companies included Chrysler, DuPont, and Steelcase. Safety programs were intended to reduce workplace accidents resulting in injuries and deaths. Over the years, such programs slowly but steadily grew in scope to encompass the general health of employees on the job. As these policies have expanded, they also have fostered some skepticism and resistance: “Wellness programs have attracted their share of criticism. Some critics argue workplace programs cross the line into employees’ personal lives.” 38 Ann Mirabito, a marketing professor at the Hankamer School of Business at Baylor University agrees there is potential for abuse: “It comes back to the corporate leader. . . . The best companies respect employees’ dignity and offer programs that help employees achieve their personal goals.” 39 Employees who exercise, eat healthily, maintain their ideal weight, abstain from smoking, and limit their alcoholic consumption have a much better chance of remaining well than do their peers who undertake none of these activities. The participating employees benefit, of course, and so do their employers, because the health insurance they provide grows cheaper as their workers draw on it less. As Michael Hiltzik, a consumer affairs columnist for the Los Angeles Times, noted, “Smoking-cessation, weight-loss and disease-screening programs give workers the impression that their employers really care about their health. Ostensibly they save money too, since a healthy workforce is cheaper to cover and less prone to absenteeism.” 40 Certainly, employers are also serving their own interests by trying to reduce the cost of insuring their workers. But are there any actual disadvantages for employees of such wellness programs that employers might unethically exploit? Hiltzik suggested one: “The dark downside is that ‘voluntary’ wellness programs also give employers a window into their workers’ health profiles that is otherwise an illegal invasion of their privacy.” 42 Thus the health histories of workers become more transparent to their bosses, and, Hiltzik and others worry, this previously confidential information could allow managers to act with bias (in employee evaluation and promotion decisions, for instance) under cover of concern about employees’ health. The potential for intrusion into employee privacy through wellness programs is alarming; further, the chance for personal health data to become public as a consequence of enrolling in such programs is concerning. Additionally, what about wellness rules that extend to workers’ behavior off the job? Is it ethical for a company to assert the right to restrict the actions of its employees when they are not on the clock? Some, such as researchers Richard J. Herzog, Katie Counts McClain, and Kymberleigh R. Rigard, argue that workers surrender a degree of privacy simply by going onto payroll: “When employees enter the workplace, they forfeit external privacy. For example, BMI [body mass index] can be visually calculated, smokers can be observed, and food intake monitored.” They acknowledge, however, that “protecting privacy and enhancing productivity can provide a delicate balance.” 41 Link to Learning As noted in previous chapters, we can find out a great deal about the ethical intentions of a company by studying its mission statement, although even the noblest statement is irrelevant if the firm fails to live up to it. Here is Anthem, Inc.’s very simple and direct mission statement as an example from a health care insurer. What impression does this statement leave with you? Would you add or delete anything to it? Why or why not? The Affordable Care Act Health care reform on a major scale emerged in the United States with the passage of the Patient Protection and Affordable Care Act, more commonly known as the Affordable Care Act (ACA) , in March 2010, during the Obama Administration. The ACA (so-called Obamacare ) represents a controversial plan that strikes its opponents as socialist. For its supporters, however, it is the first effective and comprehensive plan to extend affordable health care to the widest segment of the U.S. population. Furthermore, like most new federal policies, it has undergone tweaks and revision each year since becoming law. The ACA is funded by a combination of payments by enrollees and supplemental federal monies earmarked for this task. The ACA mandates a certain level of preventive care, a choice of physicians and health care facilities, coverage at no extra cost for individuals with preexisting health conditions, protection against the cancellation of coverage solely on the basis of becoming ill, and mental health and substance abuse treatment, all of which must be met by carriers that participate in the plan. The ACA also permits its holders to select from a number of marketplace plans as opposed to the limited number of plans typically offered by any given employer. 43 All in all, it is a far-reaching and complex plan whose full implications for employers and their employees have yet to be appreciated. Preliminary results seem to indicate that employer-provided coverage on a comprehensive scale remains a cheaper alternative for those workers eligible to receive it. 44 Given the general efficiency of group insurance policies provided by U.S. employers, an ethical issue for all managers is whether these policies offer the best care for the greatest number of employees and so should be the responsibility of management to offer whenever it is possible to do so. Current law requires all companies employing fifty or more workers to make insurance available to that part of their workforce that qualifies for such coverage (e.g., by virtue of hours worked). Is it right, however, to leave the employees of smaller firms to their own devices in securing health care? Even if the law does not require it, we hold that an ethical obligation resides with small businesses to do everything in their power to provide this coverage for their employees. Evidence of the intense debate the act has engendered is the Trump administration’s attempts, beginning in January 2017, to repeal the ACA entirely, or at least to dilute significantly many of its provisions. Nearly immediately upon his inauguration, President Trump signed Executive Order 13765 in anticipation of ending the ACA. Also that same month, the American Health Care Act was introduced in the House of Representatives, again with an eye to eliminating or seriously weakening the existing act. Much political debate within both the House and Senate ensued in 2017, with proponents of the ACA seeking to ensure its survival and opponents attempting (but, as of this writing, failing) to repeal it. The ACA represents the first far-reaching health care coverage to take effect since 1965, after many stalled or otherwise frustrated attempts. Since the passage that year of the Medicare and Medicaid Act, which provided health coverage to retired, elderly, and indigent citizens, many presidential administrations, Democrat and Republican alike, have worked to enlarge health care coverage for different segments of the national population. In addition to expanding eligibility for benefits, the Medicare and Medicaid Act had direct implications for business proprietors and their employees. For one, the act set up new automatic earnings deductions and tax schedules for workers and employers, and employers were made responsible for administering these plans, which help fund the programs’ benefits. The future of the ACA appears to depend on whether a Democrat or Republican sits in the White House and which party controls the Senate and the House in the U.S. Congress. Although legislation does hinge on the political sentiments of the president and the majority party in Congress, what is ethical does not lend itself to a majority vote. So regardless of whether the ACA survives, is revised, or is replaced entirely by new health care legislation, the provision of health care will likely continue to pose ethical implications for U.S. business and the workers who are employed by it. The ethical debate over universal health care coverage is larger even than business and its employees, of course, but it still carries immense consequences for management and labor irrespective of how the ACA or other legislation fares in the halls of government and the courts. An ethical dilemma for employers is the extent to which they should make health coverage available to their workers at affordable rates, particularly if federal and state government plans provide little or no coverage for residents and the costs of employer-provided coverage continues to climb. State-Level Experiments with Single-Payer Health Care Plans Against the backdrop of federal attempts to institute national health care over the past several decades, some individual states in the United States have used their own resources to advance this issue by proposing mandated health care coverage for their citizens. For example, in April 2006, Massachusetts passed An Act Providing Access to Affordable, Quality, Accountable Heath Care, the first significant effort at the state level to ensure near-universal health care coverage. The Massachusetts act created a state agency, the Commonwealth Health Insurance Connector Authority, to administer the extension of health care coverage to Massachusetts residents. In many ways, it served as the most significant precursor of and guide for the federal ACA, which would follow approximately four years later. By many accounts, the Massachusetts legislation has achieved its purposes with few negative consequences. As Brian C. Mooney, reporting in the Boston Globe , put it about five years after the act’s passage: “A detailed Globe examination [of the implementation of the act] makes it clear that while there have been some stumbles—and some elements of the effort merit a grade of ‘incomplete’—the overhaul, after five years, worked as well as or better than expected.” 45 The proposed Healthy California Act (SB 562) is another example. SB 562 passed in the California State Senate in June 2017. However, the Speaker of the Assembly, the lower house of the legislature, blocked a hearing of the bill at that time, and a hearing is necessary for the bill to advance to ratification. A new effort was initiated in February 2018 to permit the bill finally to be considered by the lower house. (Two differences between the California bill and the Massachusetts Act include the number of state residents who would be affected. Massachusetts has a population of about seven million compared to California’s nearly forty million. A second distinction is that SB 562 is constitutes a single-payer plan, whereas the Massachusetts Act does not.) Single-payer health care plans essentially concentrate both the administration of and payment for health care within one entity, such as a state agency. California’s effort is a very simple plan on its face but complex in its implementation. Here is how Michael Hiltzik summarized the intent of California Senate Bill 562: “The program would take over responsibility for almost all medical spending in the state, including federal programs such as Medicare and Medicaid, employer-sponsored health plans, and Affordable Care Act plans. It would relieve employers, their workers and buyers in the individual market of premiums, deductibles and copays, paying the costs out of a state fund.” 46 The bill would create a large, special program apparatus tentatively entitled Healthy California. It is contentious on many fronts, particularly in that it would create the largest single-payer health insurance plan sponsored by a U.S. state and the scope of the plan would necessitate a huge bureaucracy to administer it as well an infusion of state monies to sustain it. Furthermore, it would extend health care coverage to all residents of the state, including undocumented immigrants. A specific hurdle to passage of Healthy California is that it would cost anywhere from $370 billion to $400 billion and would require federal waivers so California could assume the administration of Medicare and Medicaid in the state as well as the federal funds currently allotted to it. All these conditions would be enormously difficult and time consuming to meet, even if the federal government were sympathetic to California’s attempts to do so. In 2018, that was decidedly not the case. Is free or inexpensive access to health care a basic human right? If so, which elements within society bear the principal responsibility for providing it: government, business, workers, all these, or other agencies or individuals? This is a foundational ethical question that would invoke different responses on the part of nearly everyone you may ask. Ethics Across Time and Cultures Free Universal Health Care Except for the United States, the largest advanced economies in the world all provide a heavily subsidized universal health care system , that is, a publicly funded system that provides primary health services to all, usually at a nominal fee only and with no exclusions based on income or wealth. Although these systems are not perfect, their continued existence seems assured, regardless of the cultural or political framework of the various countries. A logical question is why the United States would be an outlier on this issue, and whether that might change in the future. Some answers, as noted in the text, lie in the United States’ historical reliance on a mostly private system, with approximately 83 percent of health care expenses provided by the private sector through insurers and employers (in contrast, this percentage in the United Kingdom is 17). A solution that has gained traction in recent years is conversion to a single-payer system. How might this work? One article estimates that the cost of instituting a national, single-payer health care insurance program in the United States would be $32 trillion over ten years. If this estimate is accurate, would it be an exorbitant price tag for such a program, or would it be money well spent in terms of making good health care available to all citizens? 47 Critical Thinking Do you find it appropriate that health care costs be provided by a mix of private versus public sources? What advantages might single-payer health care offer over employer-provided coverage, care provided under the ACA, or privately purchased health insurance? As a nation, the United States has usually preferred a system predicated on private health care providers and insurers to pay for it. This arrangement has worked best in instituting high-quality care with minimal delays even for elective medical procedures. It has systematically failed, however, in establishing any sort of universal dispensation that is affordable for many citizens. In the early twenty-first century, the United States is moving ever so slowly and with plenty of hiccups toward some degree of national or state management of health care. Precisely where these efforts will take us may not be clear for the next several years. The political, economic, and ethical dimensions of public management of our health care drive considerable controversy and very little agreement.
business_law_i_essentials
Chapter Outline 14.1 Liability Under the Securities Act 14.2 The Framework of Securities Regulation Introduction Learning Outcome Describe the Securities Exchange Act of 1934 and its impact on business.
[ { "answer": { "ans_choice": 0, "ans_text": "The New York Stock Exchange." }, "bloom": null, "hl_context": "The SEC also oversees self-regulatory organizations ( SROs ) , or private organizations that create and enforce industry standards . These organizations are allowed to “ police ” themselves , but are subject to compliance with SEC regulations . <hl> The various well-known securities exchanges such as the New York Stock Exchange ( NYSE ) , the National Association of Securities Dealers Automated Quotation System ( NASDAQ ) , and the Chicago Board of Options are SROs . <hl> Per Section 12 ( g ) , companies with total assets exceeding $ 10 million and with 500 or more owners of any class of securities must register with the SEC unless they meets exemption requirements .", "hl_sentences": "The various well-known securities exchanges such as the New York Stock Exchange ( NYSE ) , the National Association of Securities Dealers Automated Quotation System ( NASDAQ ) , and the Chicago Board of Options are SROs .", "question": { "cloze_format": "___ is/are clauses in the U.S. Constitution that are relate to international law.", "normal_format": "What are clauses in the U.S. Constitution that relate to international law?", "question_choices": [ "The New York Stock Exchange.", "The National Association of Securities Dealers.", "The Chicago Board of Options.", "All of the above." ], "question_id": "fs-2232531356", "question_text": "The following are examples of self-regulatory organizations that the SEC oversees:" }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 2, "ans_text": "c" }, "bloom": null, "hl_context": "<hl> The SEC also oversees self-regulatory organizations ( SROs ) , or private organizations that create and enforce industry standards . <hl> These organizations are allowed to “ police ” themselves , but are subject to compliance with SEC regulations . The various well-known securities exchanges such as the New York Stock Exchange ( NYSE ) , the National Association of Securities Dealers Automated Quotation System ( NASDAQ ) , and the Chicago Board of Options are SROs . <hl> Per Section 12 ( g ) , companies with total assets exceeding $ 10 million and with 500 or more owners of any class of securities must register with the SEC unless they meets exemption requirements . <hl>", "hl_sentences": "The SEC also oversees self-regulatory organizations ( SROs ) , or private organizations that create and enforce industry standards . Per Section 12 ( g ) , companies with total assets exceeding $ 10 million and with 500 or more owners of any class of securities must register with the SEC unless they meets exemption requirements .", "question": { "cloze_format": "The types of companies that must register with the SEC are ___ .", "normal_format": "Which types of companies must register with the SEC?", "question_choices": [ "Companies with over 500 or more owners.", "Companies with total assets of $10 million.", "Companies with total assets exceeding $10 million and with 500 or more owners.", "None of the above." ], "question_id": "fs-223531356", "question_text": "Which types of companies must register with the SEC?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 3, "ans_text": "d" }, "bloom": null, "hl_context": "<hl> The Securities Exchange Act of 1934 created numerous reporting requirements for public companies . <hl> <hl> The purpose of these requirements was transparency , that is , keeping the public up to date and informed of changes that might impact securities prices . <hl> Public companies with securities registered under Section 12 or that are subject to Section 15 ( d ) must file reports with the SEC . Section 12 requires the registration of certain securities and outlines the procedures necessary to do so . Information required by Section 12 includes the nature of the business , its financial structure , the different classes of securities , the names of officers and directors along with their salaries and bonus arrangements , and financial statements . Section 15 requires brokers and dealers to register with the SEC . <hl> Individuals who buy and sell securities are considered traders , and therefore , are not subject to filing under Section 15 . <hl> <hl> Section 15 ( d ) requires registered companies to file periodic reports , such as the the annual Form 10 - K and the quarterly Form 10 - Q . <hl> These reports will be explained in detail in the next section of this chapter . The SEC Commission makes these reports available to all investors through the EDGAR website to help them make informed investment decisions . <hl> Proxy Statements . <hl> Proxy statements are documents that the SEC requires that shareholders of companies with securities registered under Section 12 of the Securities Exchange Act of 1934 receive to allow them to vote on issues that will be decided at a stockholder meeting . This process is commonly applied when voting for directors or deciding corporate actions . Even shareholders who own just one share of a company receive proxy statements ; thus , the process of sending out these statements is a large undertaking for companies . While some companies still use the mail to deliver proxy statements , others send a “ Notice of Internet Availability of Proxy Materials ” to shareholders a minimum of 40 days before the shareholders ’ meeting . <hl> Form 8 - K . <hl> Certain events require the company to file a Form 8 - K , such as a change in the company ’ s officers , mergers , or declarations of bankruptcy . These are required to be filed within four business days with the SEC . <hl> Form 10 - Q . <hl> Form 10 - Qs are quarterly unaudited financial statements that contain financial information . Since they are unaudited , they are less expensive and time-consuming for the company to prepare ; however , investors do not have the additional assurance that they have been analyzed by a neutral CPA . <hl> Form 10 - K . <hl> Form 10 - K , also known as the annual report , contains audited financial statements . Audited financial statements have been reviewed by one or more CPAs who are not affiliated with the company and who provide an objective opinion about whether or not the financial statements , such as the balance sheet , income statement , statement of changes to retained earnings , and cash flow statement , conform with accounting standards known as the Generally Accepted Accounting Principles ( GAAP ) . When the Securities Exchange Act of 1934 was first passed , most companies ’ annual reports contained only the bare minimum amount of information . However , over time , companies came to view their annual reports as a way to not only comply with SEC requirements , but also to attract new investors and impress securities analysts , or financial professionals who study various industries to make recommendations on whether a security should be bought , held , or sold . Today , many annual reports contain not only the required facts , but also compelling narratives that detail the company ’ s mission and strategic goals . The annual reports of certain companies — for example , Berkshire Hathaway , written by Warren Buffett and Charlie Munger — provide not only their opinions on their own operations , known as the management discussion , but also their thoughts on the economy overall . The Form 10 - K is a large responsibility for a company because it must disclose the company ’ s analysis of its financial conditions , potential market risks , internal controls , legal proceedings , defaults , and other information that is deemed important for investors to make sound investment decisions . <hl> Publicly owned companies that meet certain size requirements are called reporting companies , and per Section 13 ( a ) of the Securities Exchange Act of 1934 , they must file periodic disclosures . <hl> The purpose of these disclosures is to help investors make educated decisions regarding how to invest their money . These reports include information about a company ’ s line of business , corporate officers and directors , and financial statements .", "hl_sentences": "The Securities Exchange Act of 1934 created numerous reporting requirements for public companies . The purpose of these requirements was transparency , that is , keeping the public up to date and informed of changes that might impact securities prices . Individuals who buy and sell securities are considered traders , and therefore , are not subject to filing under Section 15 . Section 15 ( d ) requires registered companies to file periodic reports , such as the the annual Form 10 - K and the quarterly Form 10 - Q . Proxy Statements . Form 8 - K . Form 10 - Q . Form 10 - K . Publicly owned companies that meet certain size requirements are called reporting companies , and per Section 13 ( a ) of the Securities Exchange Act of 1934 , they must file periodic disclosures .", "question": { "cloze_format": "___ is not considered a report required by the Securities Exchange Act of 1934.", "normal_format": "All of the following are considered reports required by the Securities Exchange Act of 1934 except which one?", "question_choices": [ "Form 8k.", "Form 10 k.", "Form 10Q.", "All of the above." ], "question_id": "fs-22325313560", "question_text": "All of the following are considered reports required by the Securities Exchange Act of 1934 except:" }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 1, "ans_text": "10." }, "bloom": null, "hl_context": "<hl> Corporate insiders are those officers , directors , and beneficial owners who own more than 10 % of a class of securities , registered under Section 12 of the Securities Exchange Act of 1934 . <hl> Corporate insiders must file a statement of ownership with the SEC to be in compliance , and as of August 27 , 2002 , the SEC implemented new rules that shortened the time period to report insider transactions . It is important for a company to have internal controls and a system to ensure their corporate insiders are reporting their trades in a timely fashion . Companies that do not implement and enforce compliance procedures can become liable for the actions of their employees who fail to follow the law .", "hl_sentences": "Corporate insiders are those officers , directors , and beneficial owners who own more than 10 % of a class of securities , registered under Section 12 of the Securities Exchange Act of 1934 .", "question": { "cloze_format": "Corporate insiders include officers, directors, and beneficial owners who own _____ % of a class of securities registered under Section 12 of the Securities Exchange Act of 1934.", "normal_format": "Corporate insiders include officers, directors, and beneficial owners who own how many % of a class of securities registered under Section 12 of the Securities Exchange Act of 1934?", "question_choices": [ "5.", "10.", "15.", "20." ], "question_id": "fs-223253356", "question_text": "Corporate insiders include officers, directors, and beneficial owners who own _____ % of a class of securities registered under Section 12 of the Securities Exchange Act of 1934." }, "references_are_paraphrase": null } ]
14
14.1 Liability Under the Securities Act As explained in the previous section, many companies were initially irritated by the creation of the Securities Exchange Act of 1934, as it created a myriad of legal responsibilities and potential liabilities that impacted their business models. Companies came to recognize that they needed legal counsel and internal systems in place to ensure that they were in compliance. The liabilities for not complying with the Securities and Exchange Act of 1934 include not only monetary fines, but also civil penalties, and in some cases, criminal proceedings. Insider trading is one violation that can result in criminal charges. Insider Trading While laws vary from country to country, insider trading can be understood by what the SEC defines as the “buying or selling a security, in breach of a fiduciary duty or other relationship of trust and confidence, on the basis of material, nonpublic information about the security.” The word fiduciary comes from the Latin word for trust and refers to someone who is charged with the responsibility to act in the best interest of the other party. In the case of businesses, fiduciaries are expected to act in the best interests of their investors. However, they are often aware of information that the public is not. This knowledge has important implications as addressed by Section 10(b) and Rule 10b-5 of the Securities Exchange Act of 1934, which prohibits the purchase or sale of securities on the basis of " material nonpublic information ,"; meaning information of any kind that would impact the market price of securities that has not been disclosed to the public, i.e., insider information. The directors, large shareholders, and officers of companies frequently have access to nonpublic information that could affect the future value of a security. While an individual, as opposed to an entire company, is often charged as an insider trader, such charges can affect the entire company’s reputation, putting it in a negative light and eroding investor trust. One instance of insider trading that received widespread media attention involved Martha Stewart, who in 2003 became the subject of legal scrutiny after selling her shares in the pharmaceutical company ImClone. Following the advice of her broker, David Bacanovic, Stewart sold all of her shares of ImClone before it lost 16 percent of its value. Bacanovic represented ImClone CEO Sam Waksal, who was selling $5 million of his ImClone shares. While Bacanovic claimed he did not know why, he shared this information with Stewart. As it turned out, the FDA had not approved ImClone’s primary pharmaceutical product, Erbitux, which was a setback that only insiders were privy to. Stewart avoided a $45,673 loss by selling her shares before the public announcement. Even though Stewart may not have known exactly why ImClone would go down in value, the court decided that her decision to act upon her broker’s suggestion constituted a wrongdoing. Stewart’s role as a public figure was also relevant to this decision, as explained by SEC’s Director of Enforcement Stephen M. Cutler, who said, “It is fundamentally unfair for someone to have an edge on the market just because she has a stockbroker who is willing to break the rules and give her an illegal tip. It’s worse still when the individual engaging in the insider trading is the Chairman and CEO of a public company.” Insider trading is not always illegal. In certain instances, individuals in possession of insider knowledge can disclose their trading activity to the SEC. However, disclosure alone is not enough to make trading on the basis of insider information legally acceptable. Another instance in which the officers of publicly held companies can legally transact securities involves pre-arranged trading plans . For example, SEC Rule 10b5-1 permits executives at public companies to transact securities so long as it is arranged in good faith beforehand to take place on certain predetermined future dates and involves pre-set amounts. So long as these criteria are followed, they are granted safe harbor. Safe harbor , in this context, refers to exemption from insider trading charges for compliant pre-arranged equity trades. Schedule 13D In 1968, the Williams Act amended the Securities Exchange Act of 1934 so that investors could have advance warning of possible corporate takeovers. If someone (individual/corporation) becomes the beneficial owner of more than 5% of a company’s stock, that entity must file a Schedule 13D with the SEC within 10 days of purchase. A beneficial owner is anyone with “voting and investment power over their shares.” There are a few exceptions that apply, such as qualified institutional investors —large investors who are deemed to have sophisticated knowledge of securities such that they do not need the same level of protection as general investors. Insurance companies, state employee benefits plans, and investment companies are examples of qualified institutional investors who are allowed to report their holdings at the end of the calendar year. Insider Transactions Corporate insiders are those officers, directors, and beneficial owners who own more than 10% of a class of securities, registered under Section 12 of the Securities Exchange Act of 1934. Corporate insiders must file a statement of ownership with the SEC to be in compliance, and as of August 27, 2002, the SEC implemented new rules that shortened the time period to report insider transactions. It is important for a company to have internal controls and a system to ensure their corporate insiders are reporting their trades in a timely fashion. Companies that do not implement and enforce compliance procedures can become liable for the actions of their employees who fail to follow the law. Reporting Requirements Publicly owned companies that meet certain size requirements are called reporting companies , and per Section 13(a) of the Securities Exchange Act of 1934, they must file periodic disclosures. The purpose of these disclosures is to help investors make educated decisions regarding how to invest their money. These reports include information about a company’s line of business, corporate officers and directors, and financial statements. Form 10-K . Form 10-K, also known as the annual report, contains audited financial statements. Audited financial statements have been reviewed by one or more CPAs who are not affiliated with the company and who provide an objective opinion about whether or not the financial statements, such as the balance sheet, income statement, statement of changes to retained earnings, and cash flow statement, conform with accounting standards known as the Generally Accepted Accounting Principles (GAAP). When the Securities Exchange Act of 1934 was first passed, most companies’ annual reports contained only the bare minimum amount of information. However, over time, companies came to view their annual reports as a way to not only comply with SEC requirements, but also to attract new investors and impress securities analysts, or financial professionals who study various industries to make recommendations on whether a security should be bought, held, or sold. Today, many annual reports contain not only the required facts, but also compelling narratives that detail the company’s mission and strategic goals. The annual reports of certain companies—for example, Berkshire Hathaway, written by Warren Buffett and Charlie Munger—provide not only their opinions on their own operations, known as the management discussion , but also their thoughts on the economy overall. The Form 10-K is a large responsibility for a company because it must disclose the company’s analysis of its financial conditions, potential market risks, internal controls, legal proceedings, defaults, and other information that is deemed important for investors to make sound investment decisions. Form 10-Q . Form 10-Qs are quarterly unaudited financial statements that contain financial information. Since they are unaudited, they are less expensive and time-consuming for the company to prepare; however, investors do not have the additional assurance that they have been analyzed by a neutral CPA. Form 8-K . Certain events require the company to file a Form 8-K , such as a change in the company’s officers, mergers, or declarations of bankruptcy. These are required to be filed within four business days with the SEC. Proxy Statements . Proxy statements are documents that the SEC requires that shareholders of companies with securities registered under Section 12 of the Securities Exchange Act of 1934 receive to allow them to vote on issues that will be decided at a stockholder meeting. This process is commonly applied when voting for directors or deciding corporate actions. Even shareholders who own just one share of a company receive proxy statements; thus, the process of sending out these statements is a large undertaking for companies. While some companies still use the mail to deliver proxy statements, others send a “Notice of Internet Availability of Proxy Materials” to shareholders a minimum of 40 days before the shareholders’ meeting. Ongoing Responsibilities Businesses must stay current with changes in securities laws that impact their liabilities and responsibilities. The Exchange Act allows the SEC to make new laws, like it did in 2000 with Regulation FD, which stands for “fair disclosure”. In 2013, the SEC started to allow the use of social media channels, in certain circumstances, as a means of distributing information to shareholders. Summary These two sections have provided an overview of some of the most important points of the Securities Exchange Act of 1934. Considering the sheer number of exceptions and complexities, coupled with today’s rapidly changing technological and political climates, a successful company needs competent legal counsel to help it navigate the compliance requirements of the SEC. While certain illegal actions can be due to malicious intent, such as insider trading, this situation is not always the case; a corporate insider can fail to comply simply because he or she is not aware of the nuances of the law. 14.2 The Framework of Securities Regulation The Securities Exchange Act of 1934 In 1929, the United States stock market crashed and lost $25 billion, which would be approximately $319 billion today. The Stock Market crash of 1929 was one cause of the American Great Depression of the 1930s, which caused the failure of nearly half of American banks and created unemployment rates of almost 25 percent by 1933. These dire economic conditions created the need for breadlines , quite literally, hungry people who waited in line at charitable and government organizations for loaves of bread, and shanty towns , or areas where families who had lost their homes lived in cloistered tents on the outskirts of cities. Farmers could not even afford to harvest their crops. It was amid this social and economic unrest that Congress passed the Securities Exchange Act of 1934. Signed by President Franklin D. Roosevelt, the Securities Exchange Act of 1934 recognized that the stock market crash of 1929 was caused by wild speculation, large and sudden fluctuations, and manipulations involving securities. An article in the 1934 California Law Review described the condition of the market at the time by writing, “Artificial prices of securities were the rule rather than the exception.… The result was vast economic power, with all that implies in a democracy, in the hand of men whose ethical standards were substantially those of gangsters.” Roosevelt wanted to enact legislature to try to prevent this wild speculation in securities from happening again and to restore the public’s faith. He recognized that stock market crashes would not only destroy wealth in securities markets, but they were also instrumental to the financial security of the nation as a whole. The passing of the Security Exchange Act of 1934 was not only a reaction to the market crash, but it also represented a broad shift in the social and economic paradigms and legal frameworks of the United States. Previously, the United States had largely followed a laissez-faire economic policy. Laissez faire, as popularized by Scottish economist Adam Smith and British philosopher Herbert Spencer, describes an economic philosophy that markets function best when left to their own devices, i.e., without, or with minimal, government involvement or regulations. The rejection of laissez faire was part of a larger social shift that opposed the long hours, unsafe working conditions, and child labor that had become commonplace as a result of the Industrial Revolution. The SEC Section 4 of the Securities Exchange Act of 1934 created the Securities and Exchange Commission (SEC) to enforce its ongoing mission. The SEC is an independent agency of the United States federal government. It regulates securities laws and regulations. The first chairperson of the SEC was Joseph P. Kennedy, the father of President John F. Kennedy. The SEC is led by five presidentially appointed commissioners and has five divisions: Division of Corporation Finance, Division of Investment Management, Division of Trading and Markets, Division of Enforcement, and Division of Economic and Risk Analysis. The SEC also oversees self-regulatory organizations (SROs) , or private organizations that create and enforce industry standards. These organizations are allowed to “police” themselves, but are subject to compliance with SEC regulations. The various well-known securities exchanges such as the New York Stock Exchange (NYSE), the National Association of Securities Dealers Automated Quotation System (NASDAQ), and the Chicago Board of Options are SROs. Per Section 12(g), companies with total assets exceeding $10 million and with 500 or more owners of any class of securities must register with the SEC unless they meets exemption requirements. The SEC makes new laws in response to emerging technologies. For example, Title III of the Jumpstart Our Business Startups (JOBS) Act of 2012 was added, and in it, Section 4(a)(6) allows crowdfunding , or raising small amounts of money from many people to fund a venture or project, usually over the internet. Crowdfunding transactions are exempt from registration as long as the amount raised does not exceed $1,070,000 in a 12-month period. Secondary Markets The Securities Exchange Act of 1934 governs secondary markets , or what is typically referred to as the “stock market.” In contrast to the primary market , which involves the initial sale of a security, such as through an initial public offering (IPO) , secondary markets involve subsequent buyers and sellers of securities. One key difference is that primary market prices are set in advance, while secondary market prices are subject to constantly changing market valuations, as determined by supply and demand and investor expectations. For example, when Facebook initiated its IPO in May of 2012, the price was $38 per share, and technical issues on the NASDAQ complicated the offering. After the IPO, the stock traded sideways , meaning that it stayed within a range that did not indicate strong upward or downward movement. However, Facebook has gone on to trade at values more than four times its initial IPO valuation, due to investor beliefs and expectations. Not all stocks go up in value after their IPO; some vacillate between highs and lows and frustrate investors with their unstable valuation swings. Reporting Requirements The Securities Exchange Act of 1934 created numerous reporting requirements for public companies. The purpose of these requirements was transparency , that is, keeping the public up to date and informed of changes that might impact securities prices. Public companies with securities registered under Section 12 or that are subject to Section 15(d) must file reports with the SEC. Section 12 requires the registration of certain securities and outlines the procedures necessary to do so. Information required by Section 12 includes the nature of the business, its financial structure, the different classes of securities, the names of officers and directors along with their salaries and bonus arrangements, and financial statements. Section 15 requires brokers and dealers to register with the SEC. Individuals who buy and sell securities are considered traders, and therefore, are not subject to filing under Section 15. Section 15(d) requires registered companies to file periodic reports, such as the the annual Form 10-K and the quarterly Form 10-Q. These reports will be explained in detail in the next section of this chapter. The SEC Commission makes these reports available to all investors through the EDGAR website to help them make informed investment decisions. Registration Requirements The Securities Act of 1933 required companies initiating securities offers and exchanges to register with the SEC, unless they met exemption criteria. Section 5 of the Securities Exchange Act of 1934 built upon this foundation and made it unlawful to transact on unregistered exchanges and specifically extended this regulation to the usage of the mail and interstate commerce. 15 U.S. Code § 78f states that exchanges must not only register with the SEC, but they must also have rules that “prevent fraudulent and manipulative acts and practices, to promote just and equitable principles of trade, to foster cooperation and coordination with persons engaged in regulating, clearing, settling, processing information with respect to, and facilitating transactions in securities, to remove impediments to and perfect the mechanism of a free and open market and a national market system, and, in general, to protect investors and the public interest …” Blue Sky Laws When the Securities Exchange Act is discussed, blue sky laws are often mentioned. In 1911, Kansas bank commissioner J.N. Dolley became concerned about what he called “swindles,” in which investors at the time lost money by investing in “fake mines” or “a Central American plantation that was nine parts imagination.” Therefore, he lobbied for the first “comprehensive” securities law in the United States because, as he phrased it, these investments were backed by nothing except the blue skies of Kansas. So, state-level securities laws aimed to combat fraud are called blue sky laws. The SEC does not have jurisdiction over activities within states and does not enforce blue sky laws.
biology
Chapter Outline 43.1 Reproduction Methods 43.2 Fertilization 43.3 Human Reproductive Anatomy and Gametogenesis 43.4 Hormonal Control of Human Reproduction 43.5 Human Pregnancy and Birth 43.6 Fertilization and Early Embryonic Development 43.7 Organogenesis and Vertebrate Formation Introduction Animal reproduction is necessary for the survival of a species. In the animal kingdom, there are innumerable ways that species reproduce. Asexual reproduction produces genetically identical organisms (clones), whereas in sexual reproduction, the genetic material of two individuals combines to produce offspring that are genetically different from their parents. During sexual reproduction the male gamete (sperm) may be placed inside the female’s body for internal fertilization, or the sperm and eggs may be released into the environment for external fertilization. Seahorses, like the one shown in Figure 43.1 , provide an example of the latter. Following a mating dance, the female lays eggs in the male seahorse’s abdominal brood pouch where they are fertilized. The eggs hatch and the offspring develop in the pouch for several weeks.
[ { "answer": { "ans_choice": 0, "ans_text": "asexual" }, "bloom": null, "hl_context": "Animals produce offspring through asexual and / or sexual reproduction . Both methods have advantages and disadvantages . Asexual reproduction produces offspring that are genetically identical to the parent because the offspring are all clones of the original parent . A single individual can produce offspring asexually and large numbers of offspring can be produced quickly . <hl> In a stable or predictable environment , asexual reproduction is an effective means of reproduction because all the offspring will be adapted to that environment . <hl> In an unstable or unpredictable environment asexually-reproducing species may be at a disadvantage because all the offspring are genetically identical and may not have the genetic variation to survive in new or different conditions . On the other hand , the rapid rates of asexual reproduction may allow for a speedy response to environmental changes if individuals have mutations . An additional advantage of asexual reproduction is that colonization of new habitats may be easier when an individual does not need to find a mate to reproduce .", "hl_sentences": "In a stable or predictable environment , asexual reproduction is an effective means of reproduction because all the offspring will be adapted to that environment .", "question": { "cloze_format": "The form of reproduction that is thought to be best in a stable environment is ___.", "normal_format": "Which form of reproduction is thought to be best in a stable environment?", "question_choices": [ "asexual", "sexual", "budding", "parthenogenesis" ], "question_id": "fs-idm62799008", "question_text": "Which form of reproduction is thought to be best in a stable environment?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 1, "ans_text": "fragmentation" }, "bloom": null, "hl_context": "<hl> For example , in many sea stars , asexual reproduction is accomplished by fragmentation . <hl> <hl> Figure 43.4 illustrates a sea star for which an arm of the individual is broken off and regenerates a new sea star . <hl> Fisheries workers have been known to try to kill the sea stars eating their clam or oyster beds by cutting them in half and throwing them back into the ocean . Unfortunately for the workers , the two parts can each regenerate a new half , resulting in twice as many sea stars to prey upon the oysters and clams . Fragmentation also occurs in annelid worms , turbellarians , and poriferans . <hl> Fragmentation is the breaking of the body into two parts with subsequent regeneration . <hl> <hl> If the animal is capable of fragmentation , and the part is big enough , a separate individual will regrow . <hl>", "hl_sentences": "For example , in many sea stars , asexual reproduction is accomplished by fragmentation . Figure 43.4 illustrates a sea star for which an arm of the individual is broken off and regenerates a new sea star . Fragmentation is the breaking of the body into two parts with subsequent regeneration . If the animal is capable of fragmentation , and the part is big enough , a separate individual will regrow .", "question": { "cloze_format": "The form of reproduction that can result from damage to the original animal is ___.", "normal_format": "Which form of reproduction can result from damage to the original animal?", "question_choices": [ "asexual", "fragmentation", "budding", "parthenogenesis" ], "question_id": "fs-idp65241328", "question_text": "Which form of reproduction can result from damage to the original animal?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 3, "ans_text": "hermaphroditism" }, "bloom": null, "hl_context": "Hermaphroditism occurs in animals where one individual has both male and female reproductive parts . Invertebrates such as earthworms , slugs , tapeworms and snails , shown in Figure 43.5 , are often hermaphroditic . <hl> Hermaphrodites may self-fertilize or may mate with another of their species , fertilizing each other and both producing offspring . <hl> <hl> Self fertilization is common in animals that have limited mobility or are not motile , such as barnacles and clams . <hl>", "hl_sentences": "Hermaphrodites may self-fertilize or may mate with another of their species , fertilizing each other and both producing offspring . Self fertilization is common in animals that have limited mobility or are not motile , such as barnacles and clams .", "question": { "cloze_format": "The form of reproduction that is useful to an animal with little mobility that reproduces sexually is ___.", "normal_format": "Which form of reproduction is useful to an animal with little mobility that reproduces sexually?", "question_choices": [ "fission", "budding", "parthenogenesis", "hermaphroditism" ], "question_id": "fs-idm47940992", "question_text": "Which form of reproduction is useful to an animal with little mobility that reproduces sexually?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 0, "ans_text": "sexual reproduction" }, "bloom": null, "hl_context": "<hl> Sexual reproduction is the combination of ( usually haploid ) reproductive cells from two individuals to form a third ( usually diploid ) unique offspring . <hl> <hl> Sexual reproduction produces offspring with novel combinations of genes . <hl> This can be an adaptive advantage in unstable or unpredictable environments . As humans , we are used to thinking of animals as having two separate sexes — male and female — determined at conception . However , in the animal kingdom , there are many variations on this theme . <hl> During sexual reproduction the genetic material of two individuals is combined to produce genetically diverse offspring that differ from their parents . <hl> The genetic diversity of sexually produced offspring is thought to give species a better chance of surviving in an unpredictable or changing environment . Species that reproduce sexually must maintain two different types of individuals , males and females , which can limit the ability to colonize new habitats as both sexes must be present .", "hl_sentences": "Sexual reproduction is the combination of ( usually haploid ) reproductive cells from two individuals to form a third ( usually diploid ) unique offspring . Sexual reproduction produces offspring with novel combinations of genes . During sexual reproduction the genetic material of two individuals is combined to produce genetically diverse offspring that differ from their parents .", "question": { "cloze_format": "Genetically unique individuals are produced through ________.", "normal_format": "Through what are genetically unique individuals produced?", "question_choices": [ "sexual reproduction", "parthenogenesis", "budding", "fragmentation" ], "question_id": "fs-idm82695104", "question_text": "Genetically unique individuals are produced through ________." }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 0, "ans_text": "aquatic" }, "bloom": null, "hl_context": "<hl> External fertilization in an aquatic environment protects the eggs from drying out . <hl> Broadcast spawning can result in a greater mixture of the genes within a group , leading to higher genetic diversity and a greater chance of species survival in a hostile environment . For sessile aquatic organisms like sponges , broadcast spawning is the only mechanism for fertilization and colonization of new environments . The presence of the fertilized eggs and developing young in the water provides opportunities for predation resulting in a loss of offspring . Therefore , millions of eggs must be produced by individuals , and the offspring produced through this method must mature rapidly . The survival rate of eggs produced through broadcast spawning is low . <hl> External fertilization usually occurs in aquatic environments where both eggs and sperm are released into the water . <hl> After the sperm reaches the egg , fertilization takes place . Most external fertilization happens during the process of spawning where one or several females release their eggs and the male ( s ) release sperm in the same area , at the same time . The release of the reproductive material may be triggered by water temperature or the length of daylight . Nearly all fish spawn , as do crustaceans ( such as crabs and shrimp ) , mollusks ( such as oysters ) , squid , and echinoderms ( such as sea urchins and sea cucumbers ) . Figure 43.6 shows salmon spawning in a shallow stream . Frogs , like those shown in Figure 43.7 , corals , squid , and octopuses also spawn . Pairs of fish that are not broadcast spawners may exhibit courtship behavior . This allows the female to select a particular male . The trigger for egg and sperm release ( spawning ) causes the egg and sperm to be placed in a small area , enhancing the possibility of fertilization .", "hl_sentences": "External fertilization in an aquatic environment protects the eggs from drying out . External fertilization usually occurs in aquatic environments where both eggs and sperm are released into the water .", "question": { "cloze_format": "The type of environment that external fertilization occurs in is the ___.", "normal_format": "External fertilization occurs in which type of environment?", "question_choices": [ "aquatic", "forested", "savanna", "steppe" ], "question_id": "fs-idm65505280", "question_text": "External fertilization occurs in which type of environment?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 2, "ans_text": "ovoviparity" }, "bloom": null, "hl_context": "<hl> In ovoviparity , fertilized eggs are retained in the female , but the embryo obtains its nourishment from the egg ’ s yolk and the young are fully developed when they are hatched . <hl> This occurs in some bony fish ( like the guppy Lebistes reticulatus ) , some sharks , some lizards , some snakes ( such as the garter snake Thamnophis sirtalis ) , some vipers , and some invertebrate animals ( like the Madagascar hissing cockroach Gromphadorhina portentosa ) .", "hl_sentences": "In ovoviparity , fertilized eggs are retained in the female , but the embryo obtains its nourishment from the egg ’ s yolk and the young are fully developed when they are hatched .", "question": { "cloze_format": "___ is a term that applies to egg development within the female with nourishment derived from a yolk.", "normal_format": "Which term applies to egg development within the female with nourishment derived from a yolk?", "question_choices": [ "oviparity", "viviparity", "ovoviparity", "ovovoparity" ], "question_id": "fs-idp176671776", "question_text": "Which term applies to egg development within the female with nourishment derived from a yolk?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 0, "ans_text": "oviparity" }, "bloom": "1", "hl_context": "Internal fertilization occurs most often in land-based animals , although some aquatic animals also use this method . There are three ways that offspring are produced following internal fertilization . <hl> In oviparity , fertilized eggs are laid outside the female ’ s body and develop there , receiving nourishment from the yolk that is a part of the egg . <hl> This occurs in most bony fish , many reptiles , some cartilaginous fish , most amphibians , two mammals , and all birds . Reptiles and insects produce leathery eggs , while birds and turtles produce eggs with high concentrations of calcium carbonate in the shell , making them hard . Chicken eggs are an example of this second type .", "hl_sentences": "In oviparity , fertilized eggs are laid outside the female ’ s body and develop there , receiving nourishment from the yolk that is a part of the egg .", "question": { "cloze_format": "___ is a term that applies to egg development outside the female with nourishment derived from a yolk.", "normal_format": "Which term applies to egg development outside the female with nourishment derived from a yolk?", "question_choices": [ "oviparity", "viviparity", "ovoviparity", "ovovoparity" ], "question_id": "fs-idp325930864", "question_text": "Which term applies to egg development outside the female with nourishment derived from a yolk?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 2, "ans_text": "seminiferous tubules" }, "bloom": null, "hl_context": "<hl> Sperm mature in seminiferous tubules that are coiled inside the testes , as illustrated in Figure 43.8 . <hl> The walls of the seminiferous tubules are made up of the developing sperm cells , with the least developed sperm at the periphery of the tubule and the fully developed sperm in the lumen . The sperm cells are mixed with “ nursemaid ” cells called Sertoli cells which protect the germ cells and promote their development . Other cells mixed in the wall of the tubules are the interstitial cells of Leydig . These cells produce high levels of testosterone once the male reaches adolescence . <hl> Sperm mature in seminiferous tubules in the testes . <hl>", "hl_sentences": "Sperm mature in seminiferous tubules that are coiled inside the testes , as illustrated in Figure 43.8 . Sperm mature in seminiferous tubules in the testes .", "question": { "cloze_format": "Sperm are produced in the ________.", "normal_format": "Where are sperm produced?", "question_choices": [ "scrotum", "seminal vesicles", "seminiferous tubules", "prostate gland" ], "question_id": "fs-idp135004256", "question_text": "Sperm are produced in the ________." }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 0, "ans_text": "primary spermatocyte" }, "bloom": null, "hl_context": "<hl> Spermatogenesis , illustrated in Figure 43.12 , occurs in the wall of the seminiferous tubules ( Figure 43.8 ) , with stem cells at the periphery of the tube and the spermatozoa at the lumen of the tube . <hl> <hl> Immediately under the capsule of the tubule are diploid , undifferentiated cells . <hl> <hl> These stem cells , called spermatogonia ( singular : spermatagonium ) , go through mitosis with one offspring going on to differentiate into a sperm cell and the other giving rise to the next generation of sperm . <hl> <hl> Meiosis starts with a cell called a primary spermatocyte . <hl> At the end of the first meiotic division , a haploid cell is produced called a secondary spermatocyte . This cell is haploid and must go through another meiotic cell division . The cell produced at the end of meiosis is called a spermatid and when it reaches the lumen of the tubule and grows a flagellum , it is called a sperm cell . Four sperm result from each primary spermatocyte that goes through meiosis . Gametogenesis , the production of sperm and eggs , takes place through the process of meiosis . During meiosis , two cell divisions separate the paired chromosomes in the nucleus and then separate the chromatids that were made during an earlier stage of the cell ’ s life cycle . Meiosis produces haploid cells with half of each pair of chromosomes normally found in diploid cells . <hl> The production of sperm is called spermatogenesis and the production of eggs is called oogenesis . <hl>", "hl_sentences": "Spermatogenesis , illustrated in Figure 43.12 , occurs in the wall of the seminiferous tubules ( Figure 43.8 ) , with stem cells at the periphery of the tube and the spermatozoa at the lumen of the tube . Immediately under the capsule of the tubule are diploid , undifferentiated cells . These stem cells , called spermatogonia ( singular : spermatagonium ) , go through mitosis with one offspring going on to differentiate into a sperm cell and the other giving rise to the next generation of sperm . Meiosis starts with a cell called a primary spermatocyte . The production of sperm is called spermatogenesis and the production of eggs is called oogenesis .", "question": { "cloze_format": "The ___ cell in spermatogenesis is diploid.", "normal_format": "Which of the following cells in spermatogenesis is diploid?", "question_choices": [ "primary spermatocyte", "secondary spermatocyte", "spermatid", "sperm" ], "question_id": "fs-idm81430816", "question_text": "Which of the following cells in spermatogenesis is diploid?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 0, "ans_text": "clitoris" }, "bloom": "1", "hl_context": "The reproductive tissues of male and female humans develop similarly in utero until a low level of the hormone testosterone is released from male gonads . Testosterone causes the undeveloped tissues to differentiate into male sexual organs . When testosterone is absent , the tissues develop into female sexual tissues . Primitive gonads become testes or ovaries . <hl> Tissues that produce a penis in males produce a clitoris in females . <hl> The tissue that will become the scrotum in a male becomes the labia in a female ; that is , they are homologous structures .", "hl_sentences": "Tissues that produce a penis in males produce a clitoris in females .", "question": { "cloze_format": "The female organ that has the same embryonic origin as the penis is the ___.", "normal_format": "Which female organ has the same embryonic origin as the penis?", "question_choices": [ "clitoris", "labia majora", "greater vestibular glands", "vagina" ], "question_id": "fs-idm30849536", "question_text": "Which female organ has the same embryonic origin as the penis?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 3, "ans_text": "uterus" }, "bloom": null, "hl_context": "<hl> The uterus is a structure about the size of a woman ’ s fist . <hl> <hl> This is lined with an endometrium rich in blood vessels and mucus glands . <hl> <hl> The uterus supports the developing embryo and fetus during gestation . <hl> The thickest portion of the wall of the uterus is made of smooth muscle . Contractions of the smooth muscle in the uterus aid in passing the baby through the vagina during labor . A portion of the lining of the uterus sloughs off during each menstrual period , and then builds up again in preparation for an implantation . Part of the uterus , called the cervix , protrudes into the top of the vagina . The cervix functions as the birth canal .", "hl_sentences": "The uterus is a structure about the size of a woman ’ s fist . This is lined with an endometrium rich in blood vessels and mucus glands . The uterus supports the developing embryo and fetus during gestation .", "question": { "cloze_format": "The female organ that has an endometrial lining that will support a developing baby is the ___.", "normal_format": "Which female organ has an endometrial lining that will support a developing baby?", "question_choices": [ "labia minora", "breast", "ovaries", "uterus" ], "question_id": "fs-idp148194704", "question_text": "Which female organ has an endometrial lining that will support a developing baby?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 0, "ans_text": "one" }, "bloom": "2", "hl_context": "Egg production begins before birth , is arrested during meiosis until puberty , and then individual cells continue through at each menstrual cycle . <hl> One egg is produced from each meiotic process , with the extra chromosomes and chromatids going into polar bodies that degenerate and are reabsorbed by the body . <hl> 43.4 Hormonal Control of Human Reproduction Learning Objectives By the end of this chapter , you will be able to :", "hl_sentences": "One egg is produced from each meiotic process , with the extra chromosomes and chromatids going into polar bodies that degenerate and are reabsorbed by the body .", "question": { "cloze_format": "The amount of eggs that are produced as a result of one meiotic series of cell divisions is ___.", "normal_format": "How many eggs are produced as a result of one meiotic series of cell divisions?", "question_choices": [ "one", "two", "three", "four" ], "question_id": "fs-idm37013456", "question_text": "How many eggs are produced as a result of one meiotic series of cell divisions?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 0, "ans_text": "FSH" }, "bloom": null, "hl_context": "At the onset of puberty , the hypothalamus causes the release of FSH and LH into the male system for the first time . <hl> FSH enters the testes and stimulates the Sertoli cells to begin facilitating spermatogenesis using negative feedback , as illustrated in Figure 43.14 . <hl> <hl> LH also enters the testes and stimulates the interstitial cells of Leydig to make and release testosterone into the testes and the blood . <hl> Gametogenesis , the production of sperm and eggs , takes place through the process of meiosis . During meiosis , two cell divisions separate the paired chromosomes in the nucleus and then separate the chromatids that were made during an earlier stage of the cell ’ s life cycle . Meiosis produces haploid cells with half of each pair of chromosomes normally found in diploid cells . <hl> The production of sperm is called spermatogenesis and the production of eggs is called oogenesis . <hl>", "hl_sentences": "FSH enters the testes and stimulates the Sertoli cells to begin facilitating spermatogenesis using negative feedback , as illustrated in Figure 43.14 . LH also enters the testes and stimulates the interstitial cells of Leydig to make and release testosterone into the testes and the blood . The production of sperm is called spermatogenesis and the production of eggs is called oogenesis .", "question": { "cloze_format": "The ___ hormone causes Leydig cells to make testosterone.", "normal_format": "Which hormone causes Leydig cells to make testosterone?", "question_choices": [ "FSH", "LH", "inhibin", "estrogen" ], "question_id": "fs-idp21199008", "question_text": "Which hormone causes Leydig cells to make testosterone?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 2, "ans_text": "GnRH" }, "bloom": null, "hl_context": "The control of reproduction in females is more complex . <hl> As with the male , the anterior pituitary hormones cause the release of the hormones FSH and LH . <hl> In addition , estrogens and progesterone are released from the developing follicles . Estrogen is the reproductive hormone in females that assists in endometrial regrowth , ovulation , and calcium absorption ; it is also responsible for the secondary sexual characteristics of females . These include breast development , flaring of the hips , and a shorter period necessary for bone maturation . Progesterone assists in endometrial re-growth and inhibition of FSH and LH release . The human male and female reproductive cycles are controlled by the interaction of hormones from the hypothalamus and anterior pituitary with hormones from reproductive tissues and organs . In both sexes , the hypothalamus monitors and causes the release of hormones from the pituitary gland . <hl> When the reproductive hormone is required , the hypothalamus sends a gonadotropin-releasing hormone ( GnRH ) to the anterior pituitary . <hl> <hl> This causes the release of follicle stimulating hormone ( FSH ) and luteinizing hormone ( LH ) from the anterior pituitary into the blood . <hl> Note that the body must reach puberty in order for the adrenals to release the hormones that must be present for GnRH to be produced . Although FSH and LH are named after their functions in female reproduction , they are produced in both sexes and play important roles in controlling reproduction . Other hormones have specific functions in the male and female reproductive systems .", "hl_sentences": "As with the male , the anterior pituitary hormones cause the release of the hormones FSH and LH . When the reproductive hormone is required , the hypothalamus sends a gonadotropin-releasing hormone ( GnRH ) to the anterior pituitary . This causes the release of follicle stimulating hormone ( FSH ) and luteinizing hormone ( LH ) from the anterior pituitary into the blood .", "question": { "cloze_format": "The hormone that causes FSH and LH to be released is ___.", "normal_format": "Which hormone causes FSH and LH to be released?", "question_choices": [ "testosterone", "estrogen", "GnRH", "progesterone" ], "question_id": "fs-idm55845888", "question_text": "Which hormone causes FSH and LH to be released?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 1, "ans_text": "LH" }, "bloom": null, "hl_context": "In females , FSH stimulates development of egg cells , called ova , which develop in structures called follicles . Follicle cells produce the hormone inhibin , which inhibits FSH production . <hl> LH also plays a role in the development of ova , induction of ovulation , and stimulation of estradiol and progesterone production by the ovaries . <hl> Estradiol and progesterone are steroid hormones that prepare the body for pregnancy . Estradiol produces secondary sex characteristics in females , while both estradiol and progesterone regulate the menstrual cycle .", "hl_sentences": "LH also plays a role in the development of ova , induction of ovulation , and stimulation of estradiol and progesterone production by the ovaries .", "question": { "cloze_format": "The hormone that signals ovulation is ___.", "normal_format": "Which hormone signals ovulation?", "question_choices": [ "FSH", "LH", "inhibin", "estrogen" ], "question_id": "fs-idm171491232", "question_text": "Which hormone signals ovulation?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 3, "ans_text": "progesterone" }, "bloom": null, "hl_context": "Following ovulation , the ovarian cycle enters its luteal phase , illustrated in Figure 43.15 and the menstrual cycle enters its secretory phase , both of which run from about day 15 to 28 . The luteal and secretory phases refer to changes in the ruptured follicle . The cells in the follicle undergo physical changes and produce a structure called a corpus luteum . The corpus luteum produces estrogen and progesterone . <hl> The progesterone facilitates the regrowth of the uterine lining and inhibits the release of further FSH and LH . <hl> <hl> The uterus is being prepared to accept a fertilized egg , should it occur during this cycle . <hl> The inhibition of FSH and LH prevents any further eggs and follicles from developing , while the progesterone is elevated . The level of estrogen produced by the corpus luteum increases to a steady level for the next few days . The control of reproduction in females is more complex . As with the male , the anterior pituitary hormones cause the release of the hormones FSH and LH . In addition , estrogens and progesterone are released from the developing follicles . Estrogen is the reproductive hormone in females that assists in endometrial regrowth , ovulation , and calcium absorption ; it is also responsible for the secondary sexual characteristics of females . These include breast development , flaring of the hips , and a shorter period necessary for bone maturation . <hl> Progesterone assists in endometrial re-growth and inhibition of FSH and LH release . <hl>", "hl_sentences": "The progesterone facilitates the regrowth of the uterine lining and inhibits the release of further FSH and LH . The uterus is being prepared to accept a fertilized egg , should it occur during this cycle . Progesterone assists in endometrial re-growth and inhibition of FSH and LH release .", "question": { "cloze_format": "The ___ hormone causes the re-growth of the endometrial lining of the uterus.", "normal_format": "Which hormone causes the re-growth of the endometrial lining of the uterus?", "question_choices": [ "testosterone", "estrogen", "GnRH", "progesterone" ], "question_id": "fs-idm71478992", "question_text": "Which hormone causes the re-growth of the endometrial lining of the uterus?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 1, "ans_text": "diffusion through the endometrium" }, "bloom": null, "hl_context": "The gestation period is divided into three equal periods or trimesters . <hl> During the first two to four weeks of the first trimester , nutrition and waste are handled by the endometrial lining through diffusion . <hl> <hl> As the trimester progresses , the outer layer of the embryo begins to merge with the endometrium , and the placenta forms . <hl> <hl> This organ takes over the nutrient and waste requirements of the embryo and fetus , with the mother ’ s blood passing nutrients to the placenta and removing waste from it . <hl> Chemicals from the fetus , such as bilirubin , are processed by the mother ’ s liver for elimination . Some of the mother ’ s immunoglobulins will pass through the placenta , providing passive immunity against some potential infections .", "hl_sentences": "During the first two to four weeks of the first trimester , nutrition and waste are handled by the endometrial lining through diffusion . As the trimester progresses , the outer layer of the embryo begins to merge with the endometrium , and the placenta forms . This organ takes over the nutrient and waste requirements of the embryo and fetus , with the mother ’ s blood passing nutrients to the placenta and removing waste from it .", "question": { "cloze_format": "Nutrient and waste requirements for the developing fetus are handled during the first few weeks by ___ .", "normal_format": "By what, nutrient and waste requirements for the developing fetus are handled during the first few weeks?", "question_choices": [ "the placenta", "diffusion through the endometrium", "the chorion", "the blastocyst" ], "question_id": "fs-idp80601616", "question_text": "Nutrient and waste requirements for the developing fetus are handled during the first few weeks by:" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 0, "ans_text": "placenta" }, "bloom": null, "hl_context": "During the second trimester , the fetus grows to about 30 cm ( 12 inches ) , as shown in Figure 43.20 . It becomes active and the mother usually feels the first movements . All organs and structures continue to develop . <hl> The placenta has taken over the functions of nutrition and waste and the production of estrogen and progesterone from the corpus luteum , which has degenerated . <hl> <hl> The placenta will continue functioning up through the delivery of the baby . <hl> The gestation period is divided into three equal periods or trimesters . During the first two to four weeks of the first trimester , nutrition and waste are handled by the endometrial lining through diffusion . <hl> As the trimester progresses , the outer layer of the embryo begins to merge with the endometrium , and the placenta forms . <hl> <hl> This organ takes over the nutrient and waste requirements of the embryo and fetus , with the mother ’ s blood passing nutrients to the placenta and removing waste from it . <hl> Chemicals from the fetus , such as bilirubin , are processed by the mother ’ s liver for elimination . Some of the mother ’ s immunoglobulins will pass through the placenta , providing passive immunity against some potential infections .", "hl_sentences": "The placenta has taken over the functions of nutrition and waste and the production of estrogen and progesterone from the corpus luteum , which has degenerated . The placenta will continue functioning up through the delivery of the baby . As the trimester progresses , the outer layer of the embryo begins to merge with the endometrium , and the placenta forms . This organ takes over the nutrient and waste requirements of the embryo and fetus , with the mother ’ s blood passing nutrients to the placenta and removing waste from it .", "question": { "cloze_format": "Progesterone is made during the third trimester by the ___ .", "normal_format": "By which, progesterone is made during the third trimester?", "question_choices": [ "placenta", "endometrial lining", "chorion", "corpus luteum" ], "question_id": "fs-idp58574848", "question_text": "Progesterone is made during the third trimester by the:" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 3, "ans_text": "abstinence" }, "bloom": null, "hl_context": "Compliance with the contraceptive method is a strong contributor to the success or failure rate of any particular method . <hl> The only method that is completely effective at preventing conception is abstinence . <hl> The choice of contraceptive method depends on the goals of the woman or couple . Tubal ligation and vasectomy are considered permanent prevention , while other methods are reversible and provide short-term contraception .", "hl_sentences": "The only method that is completely effective at preventing conception is abstinence .", "question": { "cloze_format": "The contraceptive method that is 100 percent effective at preventing pregnancy is (a) ___ .", "normal_format": "Which contraceptive method is 100 percent effective at preventing pregnancy?", "question_choices": [ "condom", "oral hormonal methods", "sterilization", "abstinence" ], "question_id": "fs-idm43088464", "question_text": "Which contraceptive method is 100 percent effective at preventing pregnancy?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 1, "ans_text": "hormonal" }, "bloom": null, "hl_context": "<hl> Hormonal methods use synthetic progesterone ( sometimes in combination with estrogen ) , to inhibit the hypothalamus from releasing FSH or LH , and thus prevent an egg from being available for fertilization . <hl> <hl> The method of administering the hormone affects failure rate . <hl> <hl> The most reliable method , with a failure rate of less than 1 percent , is the implantation of the hormone under the skin . <hl> The same rate can be achieved through the sterilization procedures of vasectomy in the man or of tubal ligation in the woman , or by using an intrauterine device ( IUD ) . IUDs are inserted into the uterus and establish an inflammatory condition that prevents fertilized eggs from implanting into the uterine wall .", "hl_sentences": "Hormonal methods use synthetic progesterone ( sometimes in combination with estrogen ) , to inhibit the hypothalamus from releasing FSH or LH , and thus prevent an egg from being available for fertilization . The method of administering the hormone affects failure rate . The most reliable method , with a failure rate of less than 1 percent , is the implantation of the hormone under the skin .", "question": { "cloze_format": "The type of short term contraceptive method that is generally more effective than others is ___.", "normal_format": "Which type of short term contraceptive method is generally more effective than others?", "question_choices": [ "barrier", "hormonal", "natural family planning", "withdrawal" ], "question_id": "fs-idm175851088", "question_text": "Which type of short term contraceptive method is generally more effective than others?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 0, "ans_text": "oxytocin" }, "bloom": "1", "hl_context": "<hl> Labor is the physical efforts of expulsion of the fetus and the placenta from the uterus during birth ( parturition ) . <hl> <hl> Toward the end of the third trimester , estrogen causes receptors on the uterine wall to develop and bind the hormone oxytocin . <hl> At this time , the baby reorients , facing forward and down with the back or crown of the head engaging the cervix ( uterine opening ) . This causes the cervix to stretch and nerve impulses are sent to the hypothalamus , which signals for the release of oxytocin from the posterior pituitary . The oxytocin causes the smooth muscle in the uterine wall to contract . At the same time , the placenta releases prostaglandins into the uterus , increasing the contractions . A positive feedback relay occurs between the uterus , hypothalamus , and the posterior pituitary to assure an adequate supply of oxytocin . As more smooth muscle cells are recruited , the contractions increase in intensity and force .", "hl_sentences": "Labor is the physical efforts of expulsion of the fetus and the placenta from the uterus during birth ( parturition ) . Toward the end of the third trimester , estrogen causes receptors on the uterine wall to develop and bind the hormone oxytocin .", "question": { "cloze_format": "The ___ hormone is primarily responsible for the contractions during labor.", "normal_format": "Which hormone is primarily responsible for the contractions during labor?", "question_choices": [ "oxytocin", "estrogen", "β-HCG", "progesterone" ], "question_id": "fs-idp160654912", "question_text": "Which hormone is primarily responsible for the contractions during labor?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 1, "ans_text": "first trimester" }, "bloom": null, "hl_context": "<hl> Internal organs and body structures begin to develop during the first trimester . <hl> By five weeks , limb buds , eyes , the heart , and liver have been basically formed . By eight weeks , the term fetus applies , and the body is essentially formed , as shown in Figure 43.19 . The individual is about five centimeters ( two inches ) in length and many of the organs , such as the lungs and liver , are not yet functioning . Exposure to any toxins is especially dangerous during the first trimester , as all of the body ’ s organs and structures are going through initial development . Anything that affects that development can have a severe effect on the fetus ’ survival .", "hl_sentences": "Internal organs and body structures begin to develop during the first trimester .", "question": { "cloze_format": "Major organs begin to develop during the ___ of human gestation.", "normal_format": "Major organs begin to develop during which part of human gestation?", "question_choices": [ "fertilization", "first trimester", "second trimester", "third trimester" ], "question_id": "fs-idp71215264", "question_text": "Major organs begin to develop during which part of human gestation?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 1, "ans_text": "The trophoblast is a germ layer." }, "bloom": "4", "hl_context": "<hl> The three germs layers , shown in Figure 43.26 , are the endoderm , the ectoderm , and the mesoderm . <hl> The ectoderm gives rise to the nervous system and the epidermis . The mesoderm gives rise to the muscle cells and connective tissue in the body . The endoderm gives rise to columnar cells found in the digestive system and many internal organs . <hl> The typical blastula is a ball of cells . <hl> The next stage in embryonic development is the formation of the body plan . The cells in the blastula rearrange themselves spatially to form three layers of cells . This process is called gastrulation . During gastrulation , the blastula folds upon itself to form the three layers of cells . Each of these layers is called a germ layer and each germ layer differentiates into different organ systems . In mammals , the blastula forms the blastocyst in the next stage of development . <hl> Here the cells in the blastula arrange themselves in two layers : the inner cell mass , and an outer layer called the trophoblast . <hl> <hl> The inner cell mass is also known as the embryoblast and this mass of cells will go on to form the embryo . <hl> At this stage of development , illustrated in Figure 43.25 the inner cell mass consists of embryonic stem cells that will differentiate into the different cell types needed by the organism . The trophoblast will contribute to the placenta and nourish the embryo .", "hl_sentences": "The three germs layers , shown in Figure 43.26 , are the endoderm , the ectoderm , and the mesoderm . The typical blastula is a ball of cells . Here the cells in the blastula arrange themselves in two layers : the inner cell mass , and an outer layer called the trophoblast . The inner cell mass is also known as the embryoblast and this mass of cells will go on to form the embryo .", "question": { "cloze_format": "It is false that ___.", "normal_format": "Which of the following is false?", "question_choices": [ "The endoderm, mesoderm, ectoderm are germ layers.", "The trophoblast is a germ layer.", "The inner cell mass is a source of embryonic stem cells.", "The blastula is often a hollow ball of cells." ], "question_id": "fs-idm4742656", "question_text": "Which of the following is false?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 3, "ans_text": "does not change significantly" }, "bloom": null, "hl_context": "The development of multi-cellular organisms begins from a single-celled zygote , which undergoes rapid cell division to form the blastula . <hl> The rapid , multiple rounds of cell division are termed cleavage . <hl> Cleavage is illustrated in ( Figure 43.24 a ) . After the cleavage has produced over 100 cells , the embryo is called a blastula . The blastula is usually a spherical layer of cells ( the blastoderm ) surrounding a fluid-filled or yolk-filled cavity ( the blastocoel ) . Mammals at this stage form a structure called the blastocyst , characterized by an inner cell mass that is distinct from the surrounding blastula , shown in Figure 43.24 b . <hl> During cleavage , the cells divide without an increase in mass ; that is , one large single-celled zygote divides into multiple smaller cells . <hl> Each cell within the blastula is called a blastomere . Cleavage can take place in two ways : holoblastic ( total ) cleavage or meroblastic ( partial ) cleavage . The type of cleavage depends on the amount of yolk in the eggs . In placental mammals ( including humans ) where nourishment is provided by the mother ’ s body , the eggs have a very small amount of yolk and undergo holoblastic cleavage . Other species , such as birds , with a lot of yolk in the egg to nourish the embryo during development , undergo meroblastic cleavage .", "hl_sentences": "The rapid , multiple rounds of cell division are termed cleavage . During cleavage , the cells divide without an increase in mass ; that is , one large single-celled zygote divides into multiple smaller cells .", "question": { "cloze_format": "During cleavage, the mass of cells ___.", "normal_format": "How the mass of cells changes during cleavage?", "question_choices": [ "increases", "decreases", "doubles with every cell division", "does not change significantly" ], "question_id": "fs-idp11431424", "question_text": "During cleavage, the mass of cells:" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 0, "ans_text": "ectoderm" }, "bloom": null, "hl_context": "Organs form from the germ layers through the process of differentiation . During differentiation , the embryonic stem cells express specific sets of genes which will determine their ultimate cell type . <hl> For example , some cells in the ectoderm will express the genes specific to skin cells . <hl> As a result , these cells will differentiate into epidermal cells . The process of differentiation is regulated by cellular signaling cascades .", "hl_sentences": "For example , some cells in the ectoderm will express the genes specific to skin cells .", "question": { "cloze_format": "The ___ gives rise to the skin cells.", "normal_format": "Which of the following gives rise to the skin cells?", "question_choices": [ "ectoderm", "endoderm", "mesoderm", "none of the above" ], "question_id": "fs-idm29405328", "question_text": "Which of the following gives rise to the skin cells?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 3, "ans_text": "somites" }, "bloom": null, "hl_context": "The mesoderm that lies on either side of the vertebrate neural tube will develop into the various connective tissues of the animal body . <hl> A spatial pattern of gene expression reorganizes the mesoderm into groups of cells called somites with spaces between them . <hl> <hl> The somites , illustrated in Figure 43.29 will further develop into the ribs , lungs , and segmental ( spine ) muscle . <hl> The mesoderm also forms a structure called the notochord , which is rod-shaped and forms the central axis of the animal body .", "hl_sentences": "A spatial pattern of gene expression reorganizes the mesoderm into groups of cells called somites with spaces between them . The somites , illustrated in Figure 43.29 will further develop into the ribs , lungs , and segmental ( spine ) muscle .", "question": { "cloze_format": "The ribs form from the ________.", "normal_format": "From what do the ribs form?", "question_choices": [ "notochord", "neural plate", "neural tube", "somites" ], "question_id": "fs-idp40022656", "question_text": "The ribs form from the ________." }, "references_are_paraphrase": null } ]
43
43.1 Reproduction Methods Learning Objectives By the end of this section, you will be able to: Describe advantages and disadvantages of asexual and sexual reproduction Discuss asexual reproduction methods Discuss sexual reproduction methods Animals produce offspring through asexual and/or sexual reproduction. Both methods have advantages and disadvantages. Asexual reproduction produces offspring that are genetically identical to the parent because the offspring are all clones of the original parent. A single individual can produce offspring asexually and large numbers of offspring can be produced quickly. In a stable or predictable environment, asexual reproduction is an effective means of reproduction because all the offspring will be adapted to that environment. In an unstable or unpredictable environment asexually-reproducing species may be at a disadvantage because all the offspring are genetically identical and may not have the genetic variation to survive in new or different conditions. On the other hand, the rapid rates of asexual reproduction may allow for a speedy response to environmental changes if individuals have mutations. An additional advantage of asexual reproduction is that colonization of new habitats may be easier when an individual does not need to find a mate to reproduce. During sexual reproduction the genetic material of two individuals is combined to produce genetically diverse offspring that differ from their parents. The genetic diversity of sexually produced offspring is thought to give species a better chance of surviving in an unpredictable or changing environment. Species that reproduce sexually must maintain two different types of individuals, males and females, which can limit the ability to colonize new habitats as both sexes must be present. Asexual Reproduction Asexual reproduction occurs in prokaryotic microorganisms (bacteria) and in some eukaryotic single-celled and multi-celled organisms. There are a number of ways that animals reproduce asexually. Fission Fission , also called binary fission, occurs in prokaryotic microorganisms and in some invertebrate, multi-celled organisms. After a period of growth, an organism splits into two separate organisms. Some unicellular eukaryotic organisms undergo binary fission by mitosis. In other organisms, part of the individual separates and forms a second individual. This process occurs, for example, in many asteroid echinoderms through splitting of the central disk. Some sea anemones and some coral polyps ( Figure 43.2 ) also reproduce through fission. Budding Budding is a form of asexual reproduction that results from the outgrowth of a part of a cell or body region leading to a separation from the original organism into two individuals. Budding occurs commonly in some invertebrate animals such as corals and hydras. In hydras, a bud forms that develops into an adult and breaks away from the main body, as illustrated in Figure 43.3 , whereas in coral budding, the bud does not detach and multiplies as part of a new colony. Link to Learning Watch a video of a hydra budding. Click to view content Fragmentation Fragmentation is the breaking of the body into two parts with subsequent regeneration. If the animal is capable of fragmentation, and the part is big enough, a separate individual will regrow. For example, in many sea stars, asexual reproduction is accomplished by fragmentation. Figure 43.4 illustrates a sea star for which an arm of the individual is broken off and regenerates a new sea star. Fisheries workers have been known to try to kill the sea stars eating their clam or oyster beds by cutting them in half and throwing them back into the ocean. Unfortunately for the workers, the two parts can each regenerate a new half, resulting in twice as many sea stars to prey upon the oysters and clams. Fragmentation also occurs in annelid worms, turbellarians, and poriferans. Note that in fragmentation, there is generally a noticeable difference in the size of the individuals, whereas in fission, two individuals of approximate size are formed. Parthenogenesis Parthenogenesis is a form of asexual reproduction where an egg develops into a complete individual without being fertilized. The resulting offspring can be either haploid or diploid, depending on the process and the species. Parthenogenesis occurs in invertebrates such as water flees, rotifers, aphids, stick insects, some ants, wasps, and bees. Bees use parthenogenesis to produce haploid males (drones). If eggs are fertilized, diploid females develop, and if the fertilized eggs are fed special diet (so called royal jelly), a queen is produced. Some vertebrate animals—such as certain reptiles, amphibians, and fish—also reproduce through parthenogenesis. Although more common in plants, parthenogenesis has been observed in animal species that were segregated by sex in terrestrial or marine zoos. Two female Komodo dragons, a hammerhead shark, and a blacktop shark have produced parthenogenic young when the females have been isolated from males. Sexual Reproduction Sexual reproduction is the combination of (usually haploid) reproductive cells from two individuals to form a third (usually diploid) unique offspring. Sexual reproduction produces offspring with novel combinations of genes. This can be an adaptive advantage in unstable or unpredictable environments. As humans, we are used to thinking of animals as having two separate sexes—male and female—determined at conception. However, in the animal kingdom, there are many variations on this theme. Hermaphroditism Hermaphroditism occurs in animals where one individual has both male and female reproductive parts. Invertebrates such as earthworms, slugs, tapeworms and snails, shown in Figure 43.5 , are often hermaphroditic. Hermaphrodites may self-fertilize or may mate with another of their species, fertilizing each other and both producing offspring. Self fertilization is common in animals that have limited mobility or are not motile, such as barnacles and clams. Sex Determination Mammalian sex determination is determined genetically by the presence of X and Y chromosomes. Individuals homozygous for X (XX) are female and heterozygous individuals (XY) are male. The presence of a Y chromosome causes the development of male characteristics and its absence results in female characteristics. The XY system is also found in some insects and plants. Avian sex determination is dependent on the presence of Z and W chromosomes. Homozygous for Z (ZZ) results in a male and heterozygous (ZW) results in a female. The W appears to be essential in determining the sex of the individual, similar to the Y chromosome in mammals. Some fish, crustaceans, insects (such as butterflies and moths), and reptiles use this system. The sex of some species is not determined by genetics but by some aspect of the environment. Sex determination in some crocodiles and turtles, for example, is often dependent on the temperature during critical periods of egg development. This is referred to as environmental sex determination, or more specifically as temperature-dependent sex determination. In many turtles, cooler temperatures during egg incubation produce males and warm temperatures produce females. In some crocodiles, moderate temperatures produce males and both warm and cool temperatures produce females. In some species, sex is both genetic- and temperature-dependent. Individuals of some species change their sex during their lives, alternating between male and female. If the individual is female first, it is termed protogyny or “first female,” if it is male first, its termed protandry or “first male.” Oysters, for example, are born male, grow, and become female and lay eggs; some oyster species change sex multiple times. 43.2 Fertilization Learning Objectives By the end of this section, you will be able to: Discuss internal and external methods of fertilization Describe the methods used by animals for development of offspring during gestation Describe the anatomical adaptions that occurred in animals to facilitate reproduction Sexual reproduction starts with the combination of a sperm and an egg in a process called fertilization. This can occur either inside ( internal fertilization ) or outside ( external fertilization ) the body of the female. Humans provide an example of the former whereas seahorse reproduction is an example of the latter. External Fertilization External fertilization usually occurs in aquatic environments where both eggs and sperm are released into the water. After the sperm reaches the egg, fertilization takes place. Most external fertilization happens during the process of spawning where one or several females release their eggs and the male(s) release sperm in the same area, at the same time. The release of the reproductive material may be triggered by water temperature or the length of daylight. Nearly all fish spawn, as do crustaceans (such as crabs and shrimp), mollusks (such as oysters), squid, and echinoderms (such as sea urchins and sea cucumbers). Figure 43.6 shows salmon spawning in a shallow stream. Frogs, like those shown in Figure 43.7 , corals, squid, and octopuses also spawn. Pairs of fish that are not broadcast spawners may exhibit courtship behavior. This allows the female to select a particular male. The trigger for egg and sperm release (spawning) causes the egg and sperm to be placed in a small area, enhancing the possibility of fertilization. External fertilization in an aquatic environment protects the eggs from drying out. Broadcast spawning can result in a greater mixture of the genes within a group, leading to higher genetic diversity and a greater chance of species survival in a hostile environment. For sessile aquatic organisms like sponges, broadcast spawning is the only mechanism for fertilization and colonization of new environments. The presence of the fertilized eggs and developing young in the water provides opportunities for predation resulting in a loss of offspring. Therefore, millions of eggs must be produced by individuals, and the offspring produced through this method must mature rapidly. The survival rate of eggs produced through broadcast spawning is low. Internal Fertilization Internal fertilization occurs most often in land-based animals, although some aquatic animals also use this method. There are three ways that offspring are produced following internal fertilization. In oviparity , fertilized eggs are laid outside the female’s body and develop there, receiving nourishment from the yolk that is a part of the egg. This occurs in most bony fish, many reptiles, some cartilaginous fish, most amphibians, two mammals, and all birds. Reptiles and insects produce leathery eggs, while birds and turtles produce eggs with high concentrations of calcium carbonate in the shell, making them hard. Chicken eggs are an example of this second type. In ovoviparity , fertilized eggs are retained in the female, but the embryo obtains its nourishment from the egg’s yolk and the young are fully developed when they are hatched. This occurs in some bony fish (like the guppy Lebistes reticulatus ), some sharks, some lizards, some snakes (such as the garter snake Thamnophis sirtalis ), some vipers, and some invertebrate animals (like the Madagascar hissing cockroach Gromphadorhina portentosa ). In viviparity the young develop within the female, receiving nourishment from the mother’s blood through a placenta. The offspring develops in the female and is born alive. This occurs in most mammals, some cartilaginous fish, and a few reptiles. Internal fertilization has the advantage of protecting the fertilized egg from dehydration on land. The embryo is isolated within the female, which limits predation on the young. Internal fertilization enhances the fertilization of eggs by a specific male. Fewer offspring are produced through this method, but their survival rate is higher than that for external fertilization. The Evolution of Reproduction Once multicellular organisms evolved and developed specialized cells, some also developed tissues and organs with specialized functions. An early development in reproduction occurred in the Annelids. These organisms produce sperm and eggs from undifferentiated cells in their coelom and store them in that cavity. When the coelom becomes filled, the cells are released through an excretory opening or by the body splitting open. Reproductive organs evolved with the development of gonads that produce sperm and eggs. These cells went through meiosis, an adaption of mitosis, which reduced the number of chromosomes in each reproductive cell by half, while increasing the number of cells through cell division. Complete reproductive systems were developed in insects, with separate sexes. Sperm are made in testes and then travel through coiled tubes to the epididymis for storage. Eggs mature in the ovary. When they are released from the ovary, they travel to the uterine tubes for fertilization. Some insects have a specialized sac, called a spermatheca , which stores sperm for later use, sometimes up to a year. Fertilization can be timed with environmental or food conditions that are optimal for offspring survival. Vertebrates have similar structures, with a few differences. Non-mammals, such as birds and reptiles, have a common body opening, called a cloaca , for the digestive, excretory and reproductive systems. Coupling between birds usually involves positioning the cloaca openings opposite each other for transfer of sperm. Mammals have separate openings for the systems in the female and a uterus for support of developing offspring. The uterus has two chambers in species that produce large numbers of offspring at a time, while species that produce one offspring, such as primates, have a single uterus. Sperm transfer from the male to the female during reproduction ranges from releasing the sperm into the watery environment for external fertilization, to the joining of cloaca in birds, to the development of a penis for direct delivery into the female’s vagina in mammals. 43.3 Human Reproductive Anatomy and Gametogenesis Learning Objectives By the end of this section, you will be able to: Describe human male and female reproductive anatomies Discuss the human sexual response Describe spermatogenesis and oogenesis and discuss their differences and similarities As animals became more complex, specific organs and organ systems developed to support specific functions for the organism. The reproductive structures that evolved in land animals allow males and females to mate, fertilize internally, and support the growth and development of offspring. Human Reproductive Anatomy The reproductive tissues of male and female humans develop similarly in utero until a low level of the hormone testosterone is released from male gonads. Testosterone causes the undeveloped tissues to differentiate into male sexual organs. When testosterone is absent, the tissues develop into female sexual tissues. Primitive gonads become testes or ovaries. Tissues that produce a penis in males produce a clitoris in females. The tissue that will become the scrotum in a male becomes the labia in a female; that is, they are homologous structures. Male Reproductive Anatomy In the male reproductive system, the scrotum houses the testicles or testes (singular: testis), including providing passage for blood vessels, nerves, and muscles related to testicular function. The testes are a pair of male reproductive organs that produce sperm and some reproductive hormones. Each testis is approximately 2.5 by 3.8 cm (1.5 by 1 in) in size and divided into wedge-shaped lobules by connective tissue called septa. Coiled in each wedge are seminiferous tubules that produce sperm. Sperm are immobile at body temperature; therefore, the scrotum and penis are external to the body, as illustrated in Figure 43.8 so that a proper temperature is maintained for motility. In land mammals, the pair of testes must be suspended outside the body at about 2 ° C lower than body temperature to produce viable sperm. Infertility can occur in land mammals when the testes do not descend through the abdominal cavity during fetal development. Visual Connection Which of the following statements about the male reproductive system is false? The vas deferens carries sperm from the testes to the penis. Sperm mature in seminiferous tubules in the testes. Both the prostate and the bulbourethral glands produce components of the semen. The prostate gland is located in the testes. Sperm mature in seminiferous tubules that are coiled inside the testes, as illustrated in Figure 43.8 . The walls of the seminiferous tubules are made up of the developing sperm cells, with the least developed sperm at the periphery of the tubule and the fully developed sperm in the lumen. The sperm cells are mixed with “nursemaid” cells called Sertoli cells which protect the germ cells and promote their development. Other cells mixed in the wall of the tubules are the interstitial cells of Leydig. These cells produce high levels of testosterone once the male reaches adolescence. When the sperm have developed flagella and are nearly mature, they leave the testicles and enter the epididymis, shown in Figure 43.8 . This structure resembles a comma and lies along the top and posterior portion of the testes; it is the site of sperm maturation. The sperm leave the epididymis and enter the vas deferens (or ductus deferens), which carries the sperm, behind the bladder, and forms the ejaculatory duct with the duct from the seminal vesicles. During a vasectomy, a section of the vas deferens is removed, preventing sperm from being passed out of the body during ejaculation and preventing fertilization. Semen is a mixture of sperm and spermatic duct secretions (about 10 percent of the total) and fluids from accessory glands that contribute most of the semen’s volume. Sperm are haploid cells, consisting of a flagellum as a tail, a neck that contains the cell’s energy-producing mitochondria, and a head that contains the genetic material. Figure 43.9 shows a micrograph of human sperm as well as a diagram of the parts of the sperm. An acrosome is found at the top of the head of the sperm. This structure contains lysosomal enzymes that can digest the protective coverings that surround the egg to help the sperm penetrate and fertilize the egg. An ejaculate will contain from two to five milliliters of fluid with from 50–120 million sperm per milliliter. The bulk of the semen comes from the accessory glands associated with the male reproductive system. These are the seminal vesicles, the prostate gland, and the bulbourethral gland, all of which are illustrated in Figure 43.8 . The seminal vesicles are a pair of glands that lie along the posterior border of the urinary bladder. The glands make a solution that is thick, yellowish, and alkaline. As sperm are only motile in an alkaline environment, a basic pH is important to reverse the acidity of the vaginal environment. The solution also contains mucus, fructose (a sperm mitochondrial nutrient), a coagulating enzyme, ascorbic acid, and local-acting hormones called prostaglandins. The seminal vesicle glands account for 60 percent of the bulk of semen. The penis , illustrated in Figure 43.8 , is an organ that drains urine from the renal bladder and functions as a copulatory organ during intercourse. The penis contains three tubes of erectile tissue running through the length of the organ. These consist of a pair of tubes on the dorsal side, called the corpus cavernosum, and a single tube of tissue on the ventral side, called the corpus spongiosum. This tissue will become engorged with blood, becoming erect and hard, in preparation for intercourse. The organ is inserted into the vagina culminating with an ejaculation. During intercourse, the smooth muscle sphincters at the opening to the renal bladder close and prevent urine from entering the penis. An orgasm is a two-stage process: first, glands and accessory organs connected to the testes contract, then semen (containing sperm) is expelled through the urethra during ejaculation. After intercourse, the blood drains from the erectile tissue and the penis becomes flaccid. The walnut-shaped prostate gland surrounds the urethra, the connection to the urinary bladder. It has a series of short ducts that directly connect to the urethra. The gland is a mixture of smooth muscle and glandular tissue. The muscle provides much of the force needed for ejaculation to occur. The glandular tissue makes a thin, milky fluid that contains citrate (a nutrient), enzymes, and prostate specific antigen (PSA). PSA is a proteolytic enzyme that helps to liquefy the ejaculate several minutes after release from the male. Prostate gland secretions account for about 30 percent of the bulk of semen. The bulbourethral gland , or Cowper’s gland, releases its secretion prior to the release of the bulk of the semen. It neutralizes any acid residue in the urethra left over from urine. This usually accounts for a couple of drops of fluid in the total ejaculate and may contain a few sperm. Withdrawal of the penis from the vagina before ejaculation to prevent pregnancy may not work if sperm are present in the bulbourethral gland secretions. The location and functions of the male reproductive organs are summarized in Table 43.1 . Male Reproductive Anatomy Organ Location Function Scrotum External Carry and support testes Penis External Deliver urine, copulating organ Testes Internal Produce sperm and male hormones Seminal Vesicles Internal Contribute to semen production Prostate Gland Internal Contribute to semen production Bulbourethral Glands Internal Clean urethra at ejaculation Table 43.1 Female Reproductive Anatomy A number of reproductive structures are exterior to the female’s body. These include the breasts and the vulva, which consists of the mons pubis, clitoris, labia majora, labia minora, and the vestibular glands, all illustrated in Figure 43.10 . The location and functions of the female reproductive organs are summarized in Table 43.2 . The vulva is an area associated with the vestibule which includes the structures found in the inguinal (groin) area of women. The mons pubis is a round, fatty area that overlies the pubic symphysis. The clitoris is a structure with erectile tissue that contains a large number of sensory nerves and serves as a source of stimulation during intercourse. The labia majora are a pair of elongated folds of tissue that run posterior from the mons pubis and enclose the other components of the vulva. The labia majora derive from the same tissue that produces the scrotum in a male. The labia minora are thin folds of tissue centrally located within the labia majora. These labia protect the openings to the vagina and urethra. The mons pubis and the anterior portion of the labia majora become covered with hair during adolescence; the labia minora is hairless. The greater vestibular glands are found at the sides of the vaginal opening and provide lubrication during intercourse. Female Reproductive Anatomy Organ Location Function Clitoris External Sensory organ Mons pubis External Fatty area overlying pubic bone Labia majora External Covers labia minora Labia minora External Covers vestibule Greater vestibular glands External Secrete mucus; lubricate vagina Breast External Produce and deliver milk Ovaries Internal Carry and develop eggs Oviducts (Fallopian tubes) Internal Transport egg to uterus Uterus Internal Support developing embryo Vagina Internal Common tube for intercourse, birth canal, passing menstrual flow Table 43.2 The breasts consist of mammary glands and fat. The size of the breast is determined by the amount of fat deposited behind the gland. Each gland consists of 15 to 25 lobes that have ducts that empty at the nipple and that supply the nursing child with nutrient- and antibody-rich milk to aid development and protect the child. Internal female reproductive structures include ovaries, oviducts, the uterus , and the vagina, shown in Figure 43.10 . The pair of ovaries is held in place in the abdominal cavity by a system of ligaments. Ovaries consist of a medulla and cortex: the medulla contains nerves and blood vessels to supply the cortex with nutrients and remove waste. The outer layers of cells of the cortex are the functional parts of the ovaries. The cortex is made up of follicular cells that surround eggs that develop during fetal development in utero . During the menstrual period, a batch of follicular cells develops and prepares the eggs for release. At ovulation, one follicle ruptures and one egg is released, as illustrated in Figure 43.11 a . The oviducts , or fallopian tubes, extend from the uterus in the lower abdominal cavity to the ovaries, but they are not in contact with the ovaries. The lateral ends of the oviducts flare out into a trumpet-like structure and have a fringe of finger-like projections called fimbriae, illustrated in Figure 43.10 b . When an egg is released at ovulation, the fimbrae help the non-motile egg enter into the tube and passage to the uterus. The walls of the oviducts are ciliated and are made up mostly of smooth muscle. The cilia beat toward the middle, and the smooth muscle contracts in the same direction, moving the egg toward the uterus. Fertilization usually takes place within the oviducts and the developing embryo is moved toward the uterus for development. It usually takes the egg or embryo a week to travel through the oviduct. Sterilization in women is called a tubal ligation; it is analogous to a vasectomy in males in that the oviducts are severed and sealed. The uterus is a structure about the size of a woman’s fist. This is lined with an endometrium rich in blood vessels and mucus glands. The uterus supports the developing embryo and fetus during gestation. The thickest portion of the wall of the uterus is made of smooth muscle. Contractions of the smooth muscle in the uterus aid in passing the baby through the vagina during labor. A portion of the lining of the uterus sloughs off during each menstrual period, and then builds up again in preparation for an implantation. Part of the uterus, called the cervix, protrudes into the top of the vagina. The cervix functions as the birth canal. The vagina is a muscular tube that serves several purposes. It allows menstrual flow to leave the body. It is the receptacle for the penis during intercourse and the vessel for the delivery of offspring. It is lined by stratified squamous epithelial cells to protect the underlying tissue. Sexual Response during Intercourse The sexual response in humans is both psychological and physiological. Both sexes experience sexual arousal through psychological and physical stimulation. There are four phases of the sexual response. During phase one, called excitement, vasodilation leads to vasocongestion in erectile tissues in both men and women. The nipples, clitoris, labia, and penis engorge with blood and become enlarged. Vaginal secretions are released to lubricate the vagina to facilitate intercourse. During the second phase, called the plateau, stimulation continues, the outer third of the vaginal wall enlarges with blood, and breathing and heart rate increase. During phase three, or orgasm, rhythmic, involuntary contractions of muscles occur in both sexes. In the male, the reproductive accessory glands and tubules constrict placing semen in the urethra, then the urethra contracts expelling the semen through the penis. In women, the uterus and vaginal muscles contract in waves that may last slightly less than a second each. During phase four, or resolution, the processes described in the first three phases reverse themselves and return to their normal state. Men experience a refractory period in which they cannot maintain an erection or ejaculate for a period of time ranging from minutes to hours. Gametogenesis (Spermatogenesis and Oogenesis) Gametogenesis, the production of sperm and eggs, takes place through the process of meiosis. During meiosis, two cell divisions separate the paired chromosomes in the nucleus and then separate the chromatids that were made during an earlier stage of the cell’s life cycle. Meiosis produces haploid cells with half of each pair of chromosomes normally found in diploid cells. The production of sperm is called spermatogenesis and the production of eggs is called oogenesis . Spermatogenesis Spermatogenesis, illustrated in Figure 43.12 , occurs in the wall of the seminiferous tubules ( Figure 43.8 ), with stem cells at the periphery of the tube and the spermatozoa at the lumen of the tube. Immediately under the capsule of the tubule are diploid, undifferentiated cells. These stem cells, called spermatogonia (singular: spermatagonium), go through mitosis with one offspring going on to differentiate into a sperm cell and the other giving rise to the next generation of sperm. Meiosis starts with a cell called a primary spermatocyte. At the end of the first meiotic division, a haploid cell is produced called a secondary spermatocyte. This cell is haploid and must go through another meiotic cell division. The cell produced at the end of meiosis is called a spermatid and when it reaches the lumen of the tubule and grows a flagellum, it is called a sperm cell. Four sperm result from each primary spermatocyte that goes through meiosis. Stem cells are deposited during gestation and are present at birth through the beginning of adolescence, but in an inactive state. During adolescence, gonadotropic hormones from the anterior pituitary cause the activation of these cells and the production of viable sperm. This continues into old age. Link to Learning Visit this site to see the process of spermatogenesis. Oogenesis Oogenesis, illustrated in Figure 43.13 , occurs in the outermost layers of the ovaries. As with sperm production, oogenesis starts with a germ cell, called an oogonium (plural: oogonia), but this cell undergoes mitosis to increase in number, eventually resulting in up to about one to two million cells in the embryo. The cell starting meiosis is called a primary oocyte, as shown in Figure 43.13 . This cell will start the first meiotic division and be arrested in its progress in the first prophase stage. At the time of birth, all future eggs are in the prophase stage. At adolescence, anterior pituitary hormones cause the development of a number of follicles in an ovary. This results in the primary oocyte finishing the first meiotic division. The cell divides unequally, with most of the cellular material and organelles going to one cell, called a secondary oocyte, and only one set of chromosomes and a small amount of cytoplasm going to the other cell. This second cell is called a polar body and usually dies. A secondary meiotic arrest occurs, this time at the metaphase II stage. At ovulation, this secondary oocyte will be released and travel toward the uterus through the oviduct. If the secondary oocyte is fertilized, the cell continues through the meiosis II, producing a second polar body and a fertilized egg containing all 46 chromosomes of a human being, half of them coming from the sperm. Egg production begins before birth, is arrested during meiosis until puberty, and then individual cells continue through at each menstrual cycle. One egg is produced from each meiotic process, with the extra chromosomes and chromatids going into polar bodies that degenerate and are reabsorbed by the body. 43.4 Hormonal Control of Human Reproduction Learning Objectives By the end of this chapter, you will be able to: Describe the roles of male and female reproductive hormones Discuss the interplay of the ovarian and menstrual cycles Describe the process of menopause The human male and female reproductive cycles are controlled by the interaction of hormones from the hypothalamus and anterior pituitary with hormones from reproductive tissues and organs. In both sexes, the hypothalamus monitors and causes the release of hormones from the pituitary gland. When the reproductive hormone is required, the hypothalamus sends a gonadotropin-releasing hormone (GnRH) to the anterior pituitary. This causes the release of follicle stimulating hormone (FSH) and luteinizing hormone (LH) from the anterior pituitary into the blood. Note that the body must reach puberty in order for the adrenals to release the hormones that must be present for GnRH to be produced. Although FSH and LH are named after their functions in female reproduction, they are produced in both sexes and play important roles in controlling reproduction. Other hormones have specific functions in the male and female reproductive systems. Male Hormones At the onset of puberty, the hypothalamus causes the release of FSH and LH into the male system for the first time. FSH enters the testes and stimulates the Sertoli cells to begin facilitating spermatogenesis using negative feedback, as illustrated in Figure 43.14 . LH also enters the testes and stimulates the interstitial cells of Leydig to make and release testosterone into the testes and the blood. Testosterone , the hormone responsible for the secondary sexual characteristics that develop in the male during adolescence, stimulates spermatogenesis. These secondary sex characteristics include a deepening of the voice, the growth of facial, axillary, and pubic hair, and the beginnings of the sex drive. A negative feedback system occurs in the male with rising levels of testosterone acting on the hypothalamus and anterior pituitary to inhibit the release of GnRH, FSH, and LH. The Sertoli cells produce the hormone inhibin , which is released into the blood when the sperm count is too high. This inhibits the release of GnRH and FSH, which will cause spermatogenesis to slow down. If the sperm count reaches 20 million/ml, the Sertoli cells cease the release of inhibin, and the sperm count increases. Female Hormones The control of reproduction in females is more complex. As with the male, the anterior pituitary hormones cause the release of the hormones FSH and LH. In addition, estrogens and progesterone are released from the developing follicles. Estrogen is the reproductive hormone in females that assists in endometrial regrowth, ovulation, and calcium absorption; it is also responsible for the secondary sexual characteristics of females. These include breast development, flaring of the hips, and a shorter period necessary for bone maturation. Progesterone assists in endometrial re-growth and inhibition of FSH and LH release. In females, FSH stimulates development of egg cells, called ova, which develop in structures called follicles. Follicle cells produce the hormone inhibin, which inhibits FSH production. LH also plays a role in the development of ova, induction of ovulation, and stimulation of estradiol and progesterone production by the ovaries. Estradiol and progesterone are steroid hormones that prepare the body for pregnancy. Estradiol produces secondary sex characteristics in females, while both estradiol and progesterone regulate the menstrual cycle. The Ovarian Cycle and the Menstrual Cycle The ovarian cycle governs the preparation of endocrine tissues and release of eggs, while the menstrual cycle governs the preparation and maintenance of the uterine lining. These cycles occur concurrently and are coordinated over a 22–32 day cycle, with an average length of 28 days. The first half of the ovarian cycle is the follicular phase shown in Figure 43.15 . Slowly rising levels of FSH and LH cause the growth of follicles on the surface of the ovary. This process prepares the egg for ovulation. As the follicles grow, they begin releasing estrogens and a low level of progesterone. Progesterone maintains the endometrium to help ensure pregnancy. The trip through the fallopian tube takes about seven days. At this stage of development, called the morula, there are 30-60 cells. If pregnancy implantation does not occur, the lining is sloughed off. After about five days, estrogen levels rise and the menstrual cycle enters the proliferative phase. The endometrium begins to regrow, replacing the blood vessels and glands that deteriorated during the end of the last cycle. Visual Connection Which of the following statements about hormone regulation of the female reproductive cycle is false? LH and FSH are produced in the pituitary, and estradiol and progesterone are produced in the ovaries. Estradiol and progesterone secreted from the corpus luteum cause the endometrium to thicken. Both progesterone and estradiol are produced by the follicles. Secretion of GnRH by the hypothalamus is inhibited by low levels of estradiol but stimulated by high levels of estradiol. Just prior to the middle of the cycle (approximately day 14), the high level of estrogen causes FSH and especially LH to rise rapidly, then fall. The spike in LH causes ovulation : the most mature follicle, like that shown in Figure 43.16 , ruptures and releases its egg. The follicles that did not rupture degenerate and their eggs are lost. The level of estrogen decreases when the extra follicles degenerate. Following ovulation, the ovarian cycle enters its luteal phase, illustrated in Figure 43.15 and the menstrual cycle enters its secretory phase, both of which run from about day 15 to 28. The luteal and secretory phases refer to changes in the ruptured follicle. The cells in the follicle undergo physical changes and produce a structure called a corpus luteum. The corpus luteum produces estrogen and progesterone. The progesterone facilitates the regrowth of the uterine lining and inhibits the release of further FSH and LH. The uterus is being prepared to accept a fertilized egg, should it occur during this cycle. The inhibition of FSH and LH prevents any further eggs and follicles from developing, while the progesterone is elevated. The level of estrogen produced by the corpus luteum increases to a steady level for the next few days. If no fertilized egg is implanted into the uterus, the corpus luteum degenerates and the levels of estrogen and progesterone decrease. The endometrium begins to degenerate as the progesterone levels drop, initiating the next menstrual cycle. The decrease in progesterone also allows the hypothalamus to send GnRH to the anterior pituitary, releasing FSH and LH and starting the cycles again. Figure 43.17 visually compares the ovarian and uterine cycles as well as the commensurate hormone levels. Visual Connection Which of the following statements about the menstrual cycle is false? Progesterone levels rise during the luteal phase of the ovarian cycle and the secretory phase of the uterine cycle. Menstruation occurs just after LH and FSH levels peak. Menstruation occurs after progesterone levels drop. Estrogen levels rise before ovulation, while progesterone levels rise after. Menopause As women approach their mid-40s to mid-50s, their ovaries begin to lose their sensitivity to FSH and LH. Menstrual periods become less frequent and finally cease; this is menopause . There are still eggs and potential follicles on the ovaries, but without the stimulation of FSH and LH, they will not produce a viable egg to be released. The outcome of this is the inability to have children. The side effects of menopause include hot flashes, heavy sweating (especially at night), headaches, some hair loss, muscle pain, vaginal dryness, insomnia, depression, weight gain, and mood swings. Estrogen is involved in calcium metabolism and, without it, blood levels of calcium decrease. To replenish the blood, calcium is lost from bone which may decrease the bone density and lead to osteoporosis. Supplementation of estrogen in the form of hormone replacement therapy (HRT) can prevent bone loss, but the therapy can have negative side effects. While HRT is thought to give some protection from colon cancer, osteoporosis, heart disease, macular degeneration, and possibly depression, its negative side effects include increased risk of: stroke or heart attack, blood clots, breast cancer, ovarian cancer, endometrial cancer, gall bladder disease, and possibly dementia. Career Connection Reproductive Endocrinologist A reproductive endocrinologist is a physician who treats a variety of hormonal disorders related to reproduction and infertility in both men and women. The disorders include menstrual problems, infertility, pregnancy loss, sexual dysfunction, and menopause. Doctors may use fertility drugs, surgery, or assisted reproductive techniques (ART) in their therapy. ART involves the use of procedures to manipulate the egg or sperm to facilitate reproduction, such as in vitro fertilization. Reproductive endocrinologists undergo extensive medical training, first in a four-year residency in obstetrics and gynecology, then in a three-year fellowship in reproductive endocrinology. To be board certified in this area, the physician must pass written and oral exams in both areas. 43.5 Human Pregnancy and Birth Learning Objectives By the end of this section, you will be able to: Explain fetal development during the three trimesters of gestation Describe labor and delivery Compare the efficacy and duration of various types of contraception Discuss causes of infertility and the therapeutic options available Pregnancy begins with the fertilization of an egg and continues through to the birth of the individual. The length of time of gestation varies among animals, but is very similar among the great apes: human gestation is 266 days, while chimpanzee gestation is 237 days, a gorilla’s is 257 days, and orangutan gestation is 260 days long. The fox has a 57-day gestation. Dogs and cats have similar gestations averaging 60 days. The longest gestation for a land mammal is an African elephant at 640 days. The longest gestations among marine mammals are the beluga and sperm whales at 460 days. Human Gestation Twenty-four hours before fertilization, the egg has finished meiosis and becomes a mature oocyte. When fertilized (at conception) the egg becomes known as a zygote. The zygote travels through the oviduct to the uterus ( Figure 43.18 ). The developing embryo must implant into the wall of the uterus within seven days, or it will deteriorate and die. The outer layers of the zygote (blastocyst) grow into the endometrium by digesting the endometrial cells, and wound healing of the endometrium closes up the blastocyst into the tissue. Another layer of the blastocyst, the chorion, begins releasing a hormone called human beta chorionic gonadotropin ( β -HCG) which makes its way to the corpus luteum and keeps that structure active. This ensures adequate levels of progesterone that will maintain the endometrium of the uterus for the support of the developing embryo. Pregnancy tests determine the level of β -HCG in urine or serum. If the hormone is present, the test is positive. The gestation period is divided into three equal periods or trimesters. During the first two to four weeks of the first trimester, nutrition and waste are handled by the endometrial lining through diffusion. As the trimester progresses, the outer layer of the embryo begins to merge with the endometrium, and the placenta forms. This organ takes over the nutrient and waste requirements of the embryo and fetus, with the mother’s blood passing nutrients to the placenta and removing waste from it. Chemicals from the fetus, such as bilirubin, are processed by the mother’s liver for elimination. Some of the mother’s immunoglobulins will pass through the placenta, providing passive immunity against some potential infections. Internal organs and body structures begin to develop during the first trimester. By five weeks, limb buds, eyes, the heart, and liver have been basically formed. By eight weeks, the term fetus applies, and the body is essentially formed, as shown in Figure 43.19 . The individual is about five centimeters (two inches) in length and many of the organs, such as the lungs and liver, are not yet functioning. Exposure to any toxins is especially dangerous during the first trimester, as all of the body’s organs and structures are going through initial development. Anything that affects that development can have a severe effect on the fetus’ survival. During the second trimester, the fetus grows to about 30 cm (12 inches), as shown in Figure 43.20 . It becomes active and the mother usually feels the first movements. All organs and structures continue to develop. The placenta has taken over the functions of nutrition and waste and the production of estrogen and progesterone from the corpus luteum, which has degenerated. The placenta will continue functioning up through the delivery of the baby. During the third trimester, the fetus grows to 3 to 4 kg (6 ½ -8 ½ lbs.) and about 50 cm (19-20 inches) long, as illustrated in Figure 43.21 . This is the period of the most rapid growth during the pregnancy. Organ development continues to birth (and some systems, such as the nervous system and liver, continue to develop after birth). The mother will be at her most uncomfortable during this trimester. She may urinate frequently due to pressure on the bladder from the fetus. There may also be intestinal blockage and circulatory problems, especially in her legs. Clots may form in her legs due to pressure from the fetus on returning veins as they enter the abdominal cavity. Link to Learning Visit this site to see the stages of human fetal development. Labor and Birth Labor is the physical efforts of expulsion of the fetus and the placenta from the uterus during birth (parturition). Toward the end of the third trimester, estrogen causes receptors on the uterine wall to develop and bind the hormone oxytocin. At this time, the baby reorients, facing forward and down with the back or crown of the head engaging the cervix (uterine opening). This causes the cervix to stretch and nerve impulses are sent to the hypothalamus, which signals for the release of oxytocin from the posterior pituitary. The oxytocin causes the smooth muscle in the uterine wall to contract. At the same time, the placenta releases prostaglandins into the uterus, increasing the contractions. A positive feedback relay occurs between the uterus, hypothalamus, and the posterior pituitary to assure an adequate supply of oxytocin. As more smooth muscle cells are recruited, the contractions increase in intensity and force. There are three stages to labor. During stage one, the cervix thins and dilates. This is necessary for the baby and placenta to be expelled during birth. The cervix will eventually dilate to about 10 cm. During stage two, the baby is expelled from the uterus. The uterus contracts and the mother pushes as she compresses her abdominal muscles to aid the delivery. The last stage is the passage of the placenta after the baby has been born and the organ has completely disengaged from the uterine wall. If labor should stop before stage two is reached, synthetic oxytocin, known as Pitocin, can be administered to restart and maintain labor. An alternative to labor and delivery is the surgical delivery of the baby through a procedure called a Caesarian section. This is major abdominal surgery and can lead to post-surgical complications for the mother, but in some cases it may be the only way to safely deliver the baby. The mother’s mammary glands go through changes during the third trimester to prepare for lactation and breastfeeding. When the baby begins suckling at the breast, signals are sent to the hypothalamus causing the release of prolactin from the anterior pituitary. Prolactin causes the mammary glands to produce milk. Oxytocin is also released, promoting the release of the milk. The milk contains nutrients for the baby’s development and growth as well as immunoglobulins to protect the child from bacterial and viral infections. Contraception and Birth Control The prevention of a pregnancy comes under the terms contraception or birth control. Strictly speaking, contraception refers to preventing the sperm and egg from joining. Both terms are, however, frequently used interchangeably. Contraceptive Methods Method Examples Failure Rate in Typical Use Over 12 Months Barrier male condom, female condom, sponge, cervical cap, diaphragm, spermicides 15 to 24% Hormonal oral, patch, vaginal ring 8% injection 3% implant less than 1% Other natural family planning 12 to 25% withdrawal 27% sterilization less than 1% Table 43.3 Table 43.3 lists common methods of contraception. The failure rates listed are not the ideal rates that could be realized, but the typical rates that occur. A failure rate is the number of pregnancies resulting from the method’s use over a twelve-month period. Barrier methods, such as condoms, cervical caps, and diaphragms, block sperm from entering the uterus, preventing fertilization. Spermicides are chemicals that are placed in the vagina that kill sperm. Sponges, which are saturated with spermicides, are placed in the vagina at the cervical opening. Combinations of spermicidal chemicals and barrier methods achieve lower failure rates than do the methods when used separately. Nearly a quarter of the couples using barrier methods, natural family planning, or withdrawal can expect a failure of the method. Natural family planning is based on the monitoring of the menstrual cycle and having intercourse only during times when the egg is not available. A woman’s body temperature may rise a degree Celsius at ovulation and the cervical mucus may increase in volume and become more pliable. These changes give a general indication of when intercourse is more or less likely to result in fertilization. Withdrawal involves the removal of the penis from the vagina during intercourse, before ejaculation occurs. This is a risky method with a high failure rate due to the possible presence of sperm in the bulbourethral gland’s secretion, which may enter the vagina prior to removing the penis. Hormonal methods use synthetic progesterone (sometimes in combination with estrogen), to inhibit the hypothalamus from releasing FSH or LH, and thus prevent an egg from being available for fertilization. The method of administering the hormone affects failure rate. The most reliable method, with a failure rate of less than 1 percent, is the implantation of the hormone under the skin. The same rate can be achieved through the sterilization procedures of vasectomy in the man or of tubal ligation in the woman, or by using an intrauterine device (IUD). IUDs are inserted into the uterus and establish an inflammatory condition that prevents fertilized eggs from implanting into the uterine wall. Compliance with the contraceptive method is a strong contributor to the success or failure rate of any particular method. The only method that is completely effective at preventing conception is abstinence. The choice of contraceptive method depends on the goals of the woman or couple. Tubal ligation and vasectomy are considered permanent prevention, while other methods are reversible and provide short-term contraception. Termination of an existing pregnancy can be spontaneous or voluntary. Spontaneous termination is a miscarriage and usually occurs very early in the pregnancy, usually within the first few weeks. This occurs when the fetus cannot develop properly and the gestation is naturally terminated. Voluntary termination of a pregnancy is an abortion. Laws regulating abortion vary between states and tend to view fetal viability as the criteria for allowing or preventing the procedure. Infertility Infertility is the inability to conceive a child or carry a child to birth. About 75 percent of causes of infertility can be identified; these include diseases, such as sexually transmitted diseases that can cause scarring of the reproductive tubes in either men or women, or developmental problems frequently related to abnormal hormone levels in one of the individuals. Inadequate nutrition, especially starvation, can delay menstruation. Stress can also lead to infertility. Short-term stress can affect hormone levels, while long-term stress can delay puberty and cause less frequent menstrual cycles. Other factors that affect fertility include toxins (such as cadmium), tobacco smoking, marijuana use, gonadal injuries, and aging. If infertility is identified, several assisted reproductive technologies (ART) are available to aid conception. A common type of ART is in vitro fertilization (IVF) where an egg and sperm are combined outside the body and then placed in the uterus. Eggs are obtained from the woman after extensive hormonal treatments that prepare mature eggs for fertilization and prepare the uterus for implantation of the fertilized egg. Sperm are obtained from the man and they are combined with the eggs and supported through several cell divisions to ensure viability of the zygotes. When the embryos have reached the eight-cell stage, one or more is implanted into the woman’s uterus. If fertilization is not accomplished by simple IVF, a procedure that injects the sperm into an egg can be used. This is called intracytoplasmic sperm injection (ICSI) and is shown in Figure 43.22 . IVF procedures produce a surplus of fertilized eggs and embryos that can be frozen and stored for future use. The procedures can also result in multiple births. 43.6 Fertilization and Early Embryonic Development Learning Objectives By the end of this section, you will be able to: Discuss how fertilization occurs Explain how the embryo forms from the zygote Discuss the role of cleavage and gastrulation in animal development The process in which an organism develops from a single-celled zygote to a multi-cellular organism is complex and well-regulated. The early stages of embryonic development are also crucial for ensuring the fitness of the organism. Fertilization Fertilization, pictured in Figure 43.23 a is the process in which gametes (an egg and sperm) fuse to form a zygote. The egg and sperm each contain one set of chromosomes. To ensure that the offspring has only one complete diploid set of chromosomes, only one sperm must fuse with one egg. In mammals, the egg is protected by a layer of extracellular matrix consisting mainly of glycoproteins called the zona pellucida . When a sperm binds to the zona pellucida, a series of biochemical events, called the acrosomal reactions , take place. In placental mammals, the acrosome contains digestive enzymes that initiate the degradation of the glycoprotein matrix protecting the egg and allowing the sperm plasma membrane to fuse with the egg plasma membrane, as illustrated in Figure 43.23 b . The fusion of these two membranes creates an opening through which the sperm nucleus is transferred into the ovum. The nuclear membranes of the egg and sperm break down and the two haploid genomes condense to form a diploid genome. To ensure that no more than one sperm fertilizes the egg, once the acrosomal reactions take place at one location of the egg membrane, the egg releases proteins in other locations to prevent other sperm from fusing with the egg. If this mechanism fails, multiple sperm can fuse with the egg, resulting in polyspermy . The resulting embryo is not genetically viable and dies within a few days. Cleavage and Blastula Stage The development of multi-cellular organisms begins from a single-celled zygote, which undergoes rapid cell division to form the blastula. The rapid, multiple rounds of cell division are termed cleavage. Cleavage is illustrated in ( Figure 43.24 a ). After the cleavage has produced over 100 cells, the embryo is called a blastula. The blastula is usually a spherical layer of cells (the blastoderm) surrounding a fluid-filled or yolk-filled cavity (the blastocoel). Mammals at this stage form a structure called the blastocyst, characterized by an inner cell mass that is distinct from the surrounding blastula, shown in Figure 43.24 b . During cleavage, the cells divide without an increase in mass; that is, one large single-celled zygote divides into multiple smaller cells. Each cell within the blastula is called a blastomere. Cleavage can take place in two ways: holoblastic (total) cleavage or meroblastic (partial) cleavage. The type of cleavage depends on the amount of yolk in the eggs. In placental mammals (including humans) where nourishment is provided by the mother’s body, the eggs have a very small amount of yolk and undergo holoblastic cleavage. Other species, such as birds, with a lot of yolk in the egg to nourish the embryo during development, undergo meroblastic cleavage. In mammals, the blastula forms the blastocyst in the next stage of development. Here the cells in the blastula arrange themselves in two layers: the inner cell mass , and an outer layer called the trophoblast . The inner cell mass is also known as the embryoblast and this mass of cells will go on to form the embryo. At this stage of development, illustrated in Figure 43.25 the inner cell mass consists of embryonic stem cells that will differentiate into the different cell types needed by the organism. The trophoblast will contribute to the placenta and nourish the embryo. Link to Learning Visit the Virtual Human Embryo project at the Endowment for Human Development site to step through an interactive that shows the stages of embryo development, including micrographs and rotating 3-D images. Gastrulation The typical blastula is a ball of cells. The next stage in embryonic development is the formation of the body plan. The cells in the blastula rearrange themselves spatially to form three layers of cells. This process is called gastrulation . During gastrulation, the blastula folds upon itself to form the three layers of cells. Each of these layers is called a germ layer and each germ layer differentiates into different organ systems. The three germs layers, shown in Figure 43.26 , are the endoderm, the ectoderm, and the mesoderm. The ectoderm gives rise to the nervous system and the epidermis. The mesoderm gives rise to the muscle cells and connective tissue in the body. The endoderm gives rise to columnar cells found in the digestive system and many internal organs. Everyday Connection Are Designer Babies in Our Future? If you could prevent your child from getting a devastating genetic disease, would you do it? Would you select the sex of your child or select for their attractiveness, strength, or intelligence? How far would you go to maximize the possibility of resistance to disease? The genetic engineering of a human child, the production of "designer babies" with desirable phenotypic characteristics, was once a topic restricted to science fiction. This is the case no longer: science fiction is now overlapping into science fact. Many phenotypic choices for offspring are already available, with many more likely to be possible in the not too distant future. Which traits should be selected and how they should be selected are topics of much debate within the worldwide medical community. The ethical and moral line is not always clear or agreed upon, and some fear that modern reproductive technologies could lead to a new form of eugenics. Eugenics is the use of information and technology from a variety of sources to improve the genetic makeup of the human race. The goal of creating genetically superior humans was quite prevalent (although controversial) in several countries during the early 20 th century, but fell into disrepute when Nazi Germany developed an extensive eugenics program in the 1930's and 40's. As part of their program, the Nazis forcibly sterilized hundreds of thousands of the so-called "unfit" and killed tens of thousands of institutionally disabled people as part of a systematic program to develop a genetically superior race of Germans known as Aryans. Ever since, eugenic ideas have not been as publicly expressed, but there are still those who promote them. Efforts have been made in the past to control traits in human children using donated sperm from men with desired traits. In fact, eugenicist Robert Klark Graham established a sperm bank in 1980 that included samples exclusively from donors with high IQs. The "genius" sperm bank failed to capture the public's imagination and the operation closed in 1999. In more recent times, the procedure known as prenatal genetic diagnosis (PGD) has been developed. PGD involves the screening of human embryos as part of the process of in vitro fertilization, during which embryos are conceived and grown outside the mother's body for some period of time before they are implanted. The term PGD usually refers to both the diagnosis, selection, and the implantation of the selected embryos. In the least controversial use of PGD, embryos are tested for the presence of alleles which cause genetic diseases such as sickle cell disease, muscular dystrophy, and hemophilia, in which a single disease-causing allele or pair of alleles has been identified. By excluding embryos containing these alleles from implantation into the mother, the disease is prevented, and the unused embryos are either donated to science or discarded. There are relatively few in the worldwide medical community that question the ethics of this type of procedure, which allows individuals scared to have children because of the alleles they carry to do so successfully. The major limitation to this procedure is its expense. Not usually covered by medical insurance and thus out of reach financially for most couples, only a very small percentage of all live births use such complicated methodologies. Yet, even in cases like these where the ethical issues may seem to be clear-cut, not everyone agrees with the morality of these types of procedures. For example, to those who take the position that human life begins at conception, the discarding of unused embryos, a necessary result of PGD, is unacceptable under any circumstances. A murkier ethical situation is found in the selection of a child's sex, which is easily performed by PGD. Currently, countries such as Great Britain have banned the selection of a child's sex for reasons other than preventing sex-linked diseases. Other countries allow the procedure for "family balancing", based on the desire of some parents to have at least one child of each sex. Still others, including the United States, have taken a scattershot approach to regulating these practices, essentially leaving it to the individual practicing physician to decide which practices are acceptable and which are not. Even murkier are rare instances of disabled parents, such as those with deafness or dwarfism, who select embryos via PGD to ensure that they share their disability. These parents usually cite many positive aspects of their disabilities and associated culture as reasons for their choice, which they see as their moral right. To others, to purposely cause a disability in a child violates the basic medical principle of Primum non nocere, "first, do no harm." This procedure, although not illegal in most countries, demonstrates the complexity of ethical issues associated with choosing genetic traits in offspring. Where could this process lead? Will this technology become more affordable and how should it be used? With the ability of technology to progress rapidly and unpredictably, a lack of definitive guidelines for the use of reproductive technologies before they arise might make it difficult for legislators to keep pace once they are in fact realized, assuming the process needs any government regulation at all. Other bioethicists argue that we should only deal with technologies that exist now, and not in some uncertain future. They argue that these types of procedures will always be expensive and rare, so the fears of eugenics and "master" races are unfounded and overstated. The debate continues. 43.7 Organogenesis and Vertebrate Formation Learning Objectives By the end of this section, you will be able to: Describe the process of organogenesis Identify the anatomical axes formed in vertebrates Gastrulation leads to the formation of the three germ layers that give rise, during further development, to the different organs in the animal body. This process is called organogenesis . Organogenesis is characterized by rapid and precise movements of the cells within the embryo. Organogenesis Organs form from the germ layers through the process of differentiation. During differentiation, the embryonic stem cells express specific sets of genes which will determine their ultimate cell type. For example, some cells in the ectoderm will express the genes specific to skin cells. As a result, these cells will differentiate into epidermal cells. The process of differentiation is regulated by cellular signaling cascades. Scientists study organogenesis extensively in the lab in fruit flies ( Drosophila ) and the nematode Caenorhabditis elegans . Drosophila have segments along their bodies, and the patterning associated with the segment formation has allowed scientists to study which genes play important roles in organogenesis along the length of the embryo at different time points. The nematode C.elegans has roughly 1000 somatic cells and scientists have studied the fate of each of these cells during their development in the nematode life cycle. There is little variation in patterns of cell lineage between individuals, unlike in mammals where cell development from the embryo is dependent on cellular cues. In vertebrates, one of the primary steps during organogenesis is the formation of the neural system. The ectoderm forms epithelial cells and tissues, and neuronal tissues. During the formation of the neural system, special signaling molecules called growth factors signal some cells at the edge of the ectoderm to become epidermis cells. The remaining cells in the center form the neural plate. If the signaling by growth factors were disrupted, then the entire ectoderm would differentiate into neural tissue. The neural plate undergoes a series of cell movements where it rolls up and forms a tube called the neural tube , as illustrated in Figure 43.28 . In further development, the neural tube will give rise to the brain and the spinal cord. The mesoderm that lies on either side of the vertebrate neural tube will develop into the various connective tissues of the animal body. A spatial pattern of gene expression reorganizes the mesoderm into groups of cells called somites with spaces between them. The somites, illustrated in Figure 43.29 will further develop into the ribs, lungs, and segmental (spine) muscle. The mesoderm also forms a structure called the notochord, which is rod-shaped and forms the central axis of the animal body. Vertebrate Axis Formation Even as the germ layers form, the ball of cells still retains its spherical shape. However, animal bodies have lateral-medial (left-right), dorsal-ventral (back-belly), and anterior-posterior (head-feet) axes, illustrated in Figure 43.30 . How are these established? In one of the most seminal experiments ever to be carried out in developmental biology, Spemann and Mangold took dorsal cells from one embryo and transplanted them into the belly region of another embryo. They found that the transplanted embryo now had two notochords: one at the dorsal site from the original cells and another at the transplanted site. This suggested that the dorsal cells were genetically programmed to form the notochord and define the axis. Since then, researchers have identified many genes that are responsible for axis formation. Mutations in these genes leads to the loss of symmetry required for organism development. Animal bodies have externally visible symmetry. However, the internal organs are not symmetric. For example, the heart is on the left side and the liver on the right. The formation of the central left-right axis is an important process during development. This internal asymmetry is established very early during development and involves many genes. Research is still ongoing to fully understand the developmental implications of these genes.
introduction_to_sociology
Learning Objectives 11.1 Racial, Ethnic, and Minority Groups Understand the difference between race and ethnicity Define a majority group (dominant group) Define a minority group (subordinate group) 11.2 Stereotypes, Prejudice, and Discrimination Explain the difference between stereotypes, prejudice, discrimination, and racism Identify different types of discrimination 11.3 Theories of Race and Ethnicity Describe how major sociological perspectives view race and ethnicity Identify examples of culture of prejudice 11.4 Intergroup Relationships Explain different intergroup relations in terms of their relative levels of tolerance Give historical and/or contemporary examples of each type of intergroup relation 11.5 Race and Ethnicity in the United States Compare and contrast the different experiences of various ethnic groups in the United States Apply theories of intergroup relations and race and ethnicity to different subordinate groups Introduction to Race and Ethnicity In a mixed vocational/academic high school, Ms. Ellis grades papers for her large, diverse, 11 th grade English class. She is currently looking at the papers of three students: Jose, who is Dominican, Kim, who is Vietnamese, and Anthony, who is Italian American. Jose’s grasp of English is weak, and he doesn’t show a high degree of understanding of the themes of Hamlet . However, Ms. Ellis knows that Jose tried hard, and she also believes that, like many of his fellow Hispanic students, he will probably not go to college and continue any studies of English literature. His parents do not speak English and are not overly involved in his schooling. Jose excels in Automotive Shop, which prepares him for a job in that industry, so Ms. Ellis feels that to push him in English will not help him. She gives him a C+ and a few neutral words of encouragement without spending a lot of time pointing out where he could improve. Ms. Ellis wishes she could have more students like Kim. Kim is unfailingly polite, interested, and hardworking, even though her English still needs work. Her paper on Hamlet is far from perfect, but Ms. Ellis knows that she probably worked harder on it than anyone in the class. As is the case with most of Ms. Ellis’s Asian students, both of Kim’s parents are anxious for Kim to go to college, so even though Kim’s paper does not show much more understanding of Hamlet than Jose’s, Ms. Ellis gives her a B and writes ample comments for areas of improvement. Anthony is a thorn in Ms. Ellis’s side. In this school where most of the teachers and vocational instructors are Irish American or Italian American, Anthony has always felt at home and overconfident. His uncle is on the staff, and he has several siblings and cousins who have gone through the school. He is aggressive and disruptive in class, distracting other students and causing Ms. Ellis to spend an inordinate amount of time on maintaining discipline. Anthony’s paper is about the same level as Jose’s and Kim’s, but since English is his first language, he really should be able to perform better. Ms. Ellis gives him a C- and a few curt comments. Ms. Ellis graded three similar papers very differently. She didn’t grade them only on their merits; she relied heavily on her own knowledge of and feelings about the students themselves. Ms. Ellis was guided by her prejudices: her preconceived notions of the students’ work, attitudes, and abilities. To the extent that her prejudices affected her actions, Ms. Ellis also practiced discrimination. But what do these terms mean? Does everyone have prejudices? Is everyone guilty of discrimination? How does our society foster institutional prejudice and discrimination?
[ { "answer": { "ans_choice": 3, "ans_text": "any of the above" }, "bloom": "1", "hl_context": "<hl> The next 150 years saw the rise of American slavery , with black Africans being kidnapped from their own lands and shipped to the New World on the trans-Atlantic journey known as the Middle Passage . <hl> Once in the Americas , the black population grew until American-born blacks outnumbered those born in Africa . <hl> But colonial ( and later , American ) slave codes declared that the child of a slave was a slave , so the slave class was created . <hl> By 1869 , the slave trade was internal in the United States , with slaves being bought and sold across state lines like livestock . <hl> If Native Americans are the only minority group whose subordinate status occurred by conquest , African Americans are the exemplar minority group in the United States whose ancestors did not come here by choice . <hl> A Dutch sea captain brought the first Africans to the Virginia colony of Jamestown in 1619 and sold them as indentured servants . This was not an uncommon practice for either blacks or whites , and indentured servants were in high demand . For the next century , black and white indentured servants worked side by side . But the growing agricultural economy demanded greater and cheaper labor , and by 1705 , Virginia passed the slave codes declaring that any foreign-born non-Christian could be a slave , and that slaves were considered property . The social construction of race is also reflected in the way that names for racial categories change with changing times . It ’ s worth noting that race , in this sense , is also a system of labeling that provides a source of identity ; specific labels fall in and out of favor during different social eras . <hl> For example , the category ” negroid , ” popular in the 19th century , evolved into the term “ negro ” by the 1960s , and then this term fell from use and was replaced with “ African American . ” This latter term was intended to celebrate the multiple identities that a black person might hold , but the word choice is a poor one : it lumps together a large variety of ethnic groups under an umbrella term while excluding others who could accurately be described by the label but who do not meet the spirit of the term . <hl> For example , actress Charlize Theron is a blonde-haired , blue-eyed “ African American . ” She was born in South Africa and later became a U . S . citizen . Is her identity that of an “ African American ” as most of us understand the term ?", "hl_sentences": "The next 150 years saw the rise of American slavery , with black Africans being kidnapped from their own lands and shipped to the New World on the trans-Atlantic journey known as the Middle Passage . But colonial ( and later , American ) slave codes declared that the child of a slave was a slave , so the slave class was created . If Native Americans are the only minority group whose subordinate status occurred by conquest , African Americans are the exemplar minority group in the United States whose ancestors did not come here by choice . For example , the category ” negroid , ” popular in the 19th century , evolved into the term “ negro ” by the 1960s , and then this term fell from use and was replaced with “ African American . ” This latter term was intended to celebrate the multiple identities that a black person might hold , but the word choice is a poor one : it lumps together a large variety of ethnic groups under an umbrella term while excluding others who could accurately be described by the label but who do not meet the spirit of the term .", "question": { "cloze_format": "The racial term “African American” can refer to ___.", "normal_format": "What can the racial term “African American” refer to?", "question_choices": [ "a black person living in America", "people whose ancestors came to America through the slave trade", "a white person who originated in Africa and now lives in the United States", "any of the above" ], "question_id": "fs-id2103582", "question_text": "The racial term “African American” can refer to:" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 2, "ans_text": "Lack of power" }, "bloom": "1", "hl_context": "<hl> Note that being a numerical minority is not a characteristic of being a minority group ; sometimes larger groups can be considered minority groups due to their lack of power . <hl> It is the lack of power that is the predominant characteristic of a minority , or subordinate group . For example , consider Apartheid in South Africa , in which a numerical majority ( the black inhabitants of the country ) were exploited and oppressed by the white minority . Sociologist Louis Wirth ( 1945 ) defined a minority group as “ any group of people who , because of their physical or cultural characteristics , are singled out from the others in the society in which they live for differential and unequal treatment , and who therefore regard themselves as objects of collective discrimination . ” The term minority connotes discrimination , and in its sociological use , the term subordinate can be used interchangeably with the term minority , while the term dominant is often substituted for the group that ’ s in the majority . <hl> These definitions correlate to the concept that the dominant group is that which holds the most power in a given society , while subordinate groups are those who lack power compared to the dominant group . <hl>", "hl_sentences": "Note that being a numerical minority is not a characteristic of being a minority group ; sometimes larger groups can be considered minority groups due to their lack of power . These definitions correlate to the concept that the dominant group is that which holds the most power in a given society , while subordinate groups are those who lack power compared to the dominant group .", "question": { "cloze_format": "___ is the one defining feature of a minority group.", "normal_format": "What is the one defining feature of a minority group?", "question_choices": [ "Self-definition", "Numerical minority", "Lack of power", "Strong cultural identity" ], "question_id": "fs-id1491488", "question_text": "What is the one defining feature of a minority group?" }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 3, "ans_text": "any of the above" }, "bloom": "1", "hl_context": "<hl> Ethnicity is a term that describes shared culture — the practices , values , and beliefs of a group . <hl> <hl> This might include shared language , religion , and traditions , among other commonalities . <hl> Like race , the term ethnicity is difficult to describe and its meaning has changed over time . And like race , individuals may be identified or self-identify to ethnicities in complex , even contradictory , ways . For example , ethnic groups such as Irish , Italian American , Russian , Jewish , and Serbian might all be groups whose members are predominantly included in the racial category “ white . ” Conversely , the ethnic group British includes citizens from a multiplicity of racial backgrounds : black , white , Asian , and more , plus a variety of race combinations . These examples illustrate the complexity and overlap of these identifying terms . Ethnicity , like race , continues to be an identification method that individuals and institutions use today — whether through the census , affirmative action initiatives , non-discrimination laws , or simply in personal day-to-day relations .", "hl_sentences": "Ethnicity is a term that describes shared culture — the practices , values , and beliefs of a group . This might include shared language , religion , and traditions , among other commonalities .", "question": { "cloze_format": "Ethnicity describes shared ___ .", "normal_format": "What does ethnicity describe as shared?", "question_choices": [ "beliefs", "language", "religion", "any of the above" ], "question_id": "fs-id1386692", "question_text": "Ethnicity describes shared:" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 3, "ans_text": "Blacks under Apartheid in South Africa" }, "bloom": "1", "hl_context": "Note that being a numerical minority is not a characteristic of being a minority group ; sometimes larger groups can be considered minority groups due to their lack of power . <hl> It is the lack of power that is the predominant characteristic of a minority , or subordinate group . <hl> <hl> For example , consider Apartheid in South Africa , in which a numerical majority ( the black inhabitants of the country ) were exploited and oppressed by the white minority . <hl>", "hl_sentences": "It is the lack of power that is the predominant characteristic of a minority , or subordinate group . For example , consider Apartheid in South Africa , in which a numerical majority ( the black inhabitants of the country ) were exploited and oppressed by the white minority .", "question": { "cloze_format": "___ is an example of a numerical majority being treated as a subordinate group.", "normal_format": "Which of the following is an example of a numerical majority being treated as a subordinate group?", "question_choices": [ "Jewish people in Germany", "Creoles in New Orleans", "White people in Brazil", "Blacks under Apartheid in South Africa" ], "question_id": "fs-id1588910", "question_text": "Which of the following is an example of a numerical majority being treated as a subordinate group?" }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 1, "ans_text": "dominant groups blame subordinate groups for their problems" }, "bloom": "1", "hl_context": "<hl> Scapegoat theory , developed initially from Dollard ’ s ( 1939 ) Frustration-Aggression theory , suggests that the dominant group will displace their unfocused aggression onto a subordinate group . <hl> History has shown us many examples of the scapegoating of a subordinate group . <hl> An example from the last century is the way that Adolf Hitler was able to use the Jewish people as scapegoats for Germany ’ s social and economic problems . <hl> In the United States , recent immigrants have frequently been the scapegoat for the nation ’ s — or an individual ’ s — woes . Many states have enacted laws to disenfranchise immigrants ; these laws are popular because they let the dominant group scapegoat a subordinate group .", "hl_sentences": "Scapegoat theory , developed initially from Dollard ’ s ( 1939 ) Frustration-Aggression theory , suggests that the dominant group will displace their unfocused aggression onto a subordinate group . An example from the last century is the way that Adolf Hitler was able to use the Jewish people as scapegoats for Germany ’ s social and economic problems .", "question": { "cloze_format": "Scapegoat theory shows that ___ .", "normal_format": "What does scapegoat theory show?", "question_choices": [ "subordinate groups blame dominant groups for their problems", "dominant groups blame subordinate groups for their problems", "some people are predisposed to prejudice", "all of the above" ], "question_id": "fs-id1291763", "question_text": "Scapegoat theory shows that:" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 3, "ans_text": "all of the above" }, "bloom": "1", "hl_context": "As stated above , stereotypes are oversimplified ideas about groups of people . <hl> Stereotypes can be based on race , ethnicity , age , gender , sexual orientation — almost any characteristic . <hl> They may be positive ( usually about one ’ s own group , such as when women suggest they are less likely to complain about physical pain ) but are often negative ( usually toward other groups , such as when members of a dominant racial group suggest that a subordinate racial group is stupid or lazy ) . In either case , the stereotype is a generalization that doesn ’ t take individual differences into account .", "hl_sentences": "Stereotypes can be based on race , ethnicity , age , gender , sexual orientation — almost any characteristic .", "question": { "cloze_format": "Stereotypes can be based on ___.", "normal_format": "What can stereotypes be based on?", "question_choices": [ "race", "ethnicity", "gender", "all of the above" ], "question_id": "fs-id1363101", "question_text": "Stereotypes can be based on:" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 1, "ans_text": "Biased actions against an individual or group" }, "bloom": "1", "hl_context": "<hl> While prejudice refers to biased thinking , discrimination consists of actions against a group of people . <hl> Discrimination can be based on age , religion , health , and other indicators ; race-based discrimination and antidiscrimination laws strive to address this set of social problems .", "hl_sentences": "While prejudice refers to biased thinking , discrimination consists of actions against a group of people .", "question": { "cloze_format": "Discrimination is (the) ___.", "normal_format": "What is discrimination?", "question_choices": [ "Biased thoughts against an individual or group", "Biased actions against an individual or group", "Belief that a race different from yours is inferior", "Another word for stereotyping" ], "question_id": "fs-id2839132", "question_text": "What is discrimination?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 2, "ans_text": "It does not need the actions of individuals to continue." }, "bloom": null, "hl_context": "However , discrimination cannot be erased from our culture just by enacting laws to abolish it . Even if a magic pill managed to eradicate racism from each individual ’ s psyche , society itself would maintain it . <hl> Sociologist Émile Durkheim calls racism a social fact , meaning that it does not require the action of individuals to continue . <hl> The reasons for this are complex and relate to the educational , criminal , economic , and political systems that exist . For example , when a newspaper prints the race of individuals accused of a crime , it may enhance stereotypes of a certain minority . Another example of racist practices is racial steering , in which real estate agents direct prospective homeowners toward or away from certain neighborhoods based on their race . Racist attitudes and beliefs are often more insidious and hard to pin down than specific racist practices .", "hl_sentences": "Sociologist Émile Durkheim calls racism a social fact , meaning that it does not require the action of individuals to continue .", "question": { "cloze_format": "The best explanation of racism as a social fact is that ___ .", "normal_format": "Which of the following is the best explanation of racism as a social fact?", "question_choices": [ "It needs to be eradicated by laws.", "It is like a magic pill.", "It does not need the actions of individuals to continue.", "None of the above" ], "question_id": "fs-id1306686", "question_text": "Which of the following is the best explanation of racism as a social fact?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 2, "ans_text": "white privilege" }, "bloom": null, "hl_context": "<hl> Institutional discrimination can also involve the promotion of a group ’ s status , such as occurs with white privilege . <hl> While most white people are willing to admit that non-white people live with a set of disadvantages due to the color of their skin , very few white people are willing to acknowledge the benefits they receive simply by being white . <hl> White privilege refers to the fact that dominant groups often accept their experience as the normative ( and hence , superior ) experience . <hl> <hl> Failure to recognize this “ normality ” as race-based is an example of a dominant group institutionalizing racism . <hl> Feminist sociologist Peggy McIntosh ( 1988 ) described several examples of “ white privilege . ” For instance , white women can easily find makeup that matches their skin tone . White people can be assured that , most of the time , they will be dealing with authority figures of their own race . How many other examples of white privilege can you think of ?", "hl_sentences": "Institutional discrimination can also involve the promotion of a group ’ s status , such as occurs with white privilege . White privilege refers to the fact that dominant groups often accept their experience as the normative ( and hence , superior ) experience . Failure to recognize this “ normality ” as race-based is an example of a dominant group institutionalizing racism .", "question": { "cloze_format": "As a Caucasian in the United States, being reasonably sure that you will be dealing with authority figures of the same race as you is a result of (the) ___ .", "normal_format": "As a Caucasian in the United States, being reasonably sure that you will be dealing with authority figures of the same race as you is a result of what?", "question_choices": [ "intersection theory", "conflict theory", "white privilege", "scapegoating theory" ], "question_id": "fs-id2274870", "question_text": "As a Caucasian in the United States, being reasonably sure that you will be dealing with authority figures of the same race as you is a result of:" }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 1, "ans_text": "stereotyping" }, "bloom": "1", "hl_context": "Culture of prejudice refers to the theory that prejudice is embedded in our culture . We grow up surrounded by images of stereotypes and casual expressions of racism and prejudice . <hl> Consider the casually racist imagery on grocery store shelves or the stereotypes that fill popular movies and advertisements . <hl> <hl> It is easy to see how someone living in the Northeastern United States , who may know no Mexican Americans personally , might gain a stereotyped impression from such sources as Speedy Gonzalez or Taco Bell ’ s talking Chihuahua . <hl> Because we are all exposed to these images and thoughts , it is impossible to know to what extent they have influenced our thought processes . 11.4 Intergroup Relationships", "hl_sentences": "Consider the casually racist imagery on grocery store shelves or the stereotypes that fill popular movies and advertisements . It is easy to see how someone living in the Northeastern United States , who may know no Mexican Americans personally , might gain a stereotyped impression from such sources as Speedy Gonzalez or Taco Bell ’ s talking Chihuahua .", "question": { "cloze_format": "Speedy Gonzalez is an example of ___.", "normal_format": "What is Speedy Gonzalez an example of?", "question_choices": [ "intersection theory", "stereotyping", "interactionist view", "culture of prejudice" ], "question_id": "fs-id2368853", "question_text": "Speedy Gonzalez is an example of:" }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 2, "ans_text": "Genocide" }, "bloom": null, "hl_context": "Intergroup relations ( relationships between different groups of people ) range along a spectrum between tolerance and intolerance . The most tolerant form of intergroup relations is pluralism , in which no distinction is made between minority and majority groups , but instead there ’ s equal standing . <hl> At the other end of the continuum are amalgamation , expulsion , and even genocide — stark examples of intolerant intergroup relations . <hl>", "hl_sentences": "At the other end of the continuum are amalgamation , expulsion , and even genocide — stark examples of intolerant intergroup relations .", "question": { "cloze_format": "The intergroup relation that displays the least tolerance is ___.", "normal_format": "Which intergroup relation displays the least tolerance?", "question_choices": [ "Segregation", "Assimilation", "Genocide", "Expulsion" ], "question_id": "fs-id1169033060750", "question_text": "Which intergroup relation displays the least tolerance?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 3, "ans_text": "Separate but equal" }, "bloom": "1", "hl_context": "<hl> Segregation refers to the physical separation of two groups , particularly in residence , but also in workplace and social functions . <hl> <hl> It is important to distinguish between de jure segregation ( segregation that is enforced by law ) and de facto segregation ( segregation that occurs without laws but because of other factors ) . <hl> <hl> A stark example of de jure segregation is the apartheid movement of South Africa , which existed from 1948 to 1994 . <hl> Under apartheid , black South Africans were stripped of their civil rights and forcibly relocated to areas that segregated them physically from their white compatriots . Only after decades of degradation , violent uprisings , and international advocacy was apartheid finally abolished .", "hl_sentences": "Segregation refers to the physical separation of two groups , particularly in residence , but also in workplace and social functions . It is important to distinguish between de jure segregation ( segregation that is enforced by law ) and de facto segregation ( segregation that occurs without laws but because of other factors ) . A stark example of de jure segregation is the apartheid movement of South Africa , which existed from 1948 to 1994 .", "question": { "cloze_format": "The ___ doctrine justified legal segregation in the South.", "normal_format": "What doctrine justified legal segregation in the South?", "question_choices": [ "Jim Crow", "Plessey v. Ferguson", "De jure", "Separate but equal" ], "question_id": "fs-id1169033068658", "question_text": "What doctrine justified legal segregation in the South?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 1, "ans_text": "Pluralism" }, "bloom": null, "hl_context": "<hl> Pluralism is represented by the ideal of the United States as a “ salad bowl ” : a great mixture of different cultures where each culture retains its own identity and yet adds to the flavor of the whole . <hl> True pluralism is characterized by mutual respect on the part of all cultures , both dominant and subordinate , creating a multicultural environment of acceptance . In reality , true pluralism is a difficult goal to reach . In the United States , the mutual respect required by pluralism is often missing , and the nation ’ s past pluralist model of a melting pot posits a society where cultural differences aren ’ t embraced as much as erased .", "hl_sentences": "Pluralism is represented by the ideal of the United States as a “ salad bowl ” : a great mixture of different cultures where each culture retains its own identity and yet adds to the flavor of the whole .", "question": { "cloze_format": "The intergroup relationship that is represented by the “salad bowl” metaphor is called ___.", "normal_format": "What intergroup relationship is represented by the “salad bowl” metaphor?", "question_choices": [ "Assimilation", "Pluralism", "Amalgamation", "Segregation" ], "question_id": "fs-id1169033058285", "question_text": "What intergroup relationship is represented by the “salad bowl” metaphor?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 0, "ans_text": "melting pot" }, "bloom": null, "hl_context": "<hl> Amalgamation is the process by which a minority group and a majority group combine to form a new group . <hl> <hl> Amalgamation creates the classic “ melting pot ” analogy ; unlike the “ salad bowl , ” in which each culture retains its individuality , the “ melting pot ” ideal sees the combination of cultures resulting in a new culture entirely . <hl>", "hl_sentences": "Amalgamation is the process by which a minority group and a majority group combine to form a new group . Amalgamation creates the classic “ melting pot ” analogy ; unlike the “ salad bowl , ” in which each culture retains its individuality , the “ melting pot ” ideal sees the combination of cultures resulting in a new culture entirely .", "question": { "cloze_format": "Amalgamation is represented by the _____________ metaphor.", "normal_format": "What metaphor represents Amalgamation?", "question_choices": [ "melting pot", "Statue of Liberty", "salad bowl", "separate but equal" ], "question_id": "fs-id1169033063966", "question_text": "Amalgamation is represented by the _____________ metaphor." }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 3, "ans_text": "They are the only group that did not come here as immigrants." }, "bloom": "1", "hl_context": "<hl> However , Native Americans ( some of whom now wished to be called American Indians so as to avoid the “ savage ” connotations of the term “ native ” ) still suffer the effects of centuries of degradation . <hl> Long-term poverty , inadequate education , cultural dislocation , and high rates of unemployment contribute to Native American populations falling to the bottom of the economic spectrum . Native Americans also suffer disproportionately with lower life expectancies than most groups in the United States . <hl> The only nonimmigrant ethnic group in the United States , Native Americans were once a large population but by 2010 made up only 0.9 percent of U . S . populace ( U . S . Census 2010 ) . <hl>", "hl_sentences": "However , Native Americans ( some of whom now wished to be called American Indians so as to avoid the “ savage ” connotations of the term “ native ” ) still suffer the effects of centuries of degradation . The only nonimmigrant ethnic group in the United States , Native Americans were once a large population but by 2010 made up only 0.9 percent of U . S . populace ( U . S . Census 2010 ) .", "question": { "cloze_format": "The reason that makes Native Americans unique as a subordinate group in the United States is that ___ .", "normal_format": "What makes Native Americans unique as a subordinate group in the United States?", "question_choices": [ "They are the only group that experienced expulsion.", "They are the only group that was segregated.", "They are the only group that was enslaved.", "They are the only group that did not come here as immigrants." ], "question_id": "fs-id2316262", "question_text": "What makes Native Americans unique as a subordinate group in the United States?" }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 1, "ans_text": "Asian Americans" }, "bloom": "1", "hl_context": "<hl> Asian Americans certainly have been subject to their share of racial prejudice , despite the seemingly positive stereotype as the model minority . <hl> <hl> The model minority stereotype is applied to a minority group that is seen as reaching significant educational , professional , and socioeconomic levels without challenging the existing establishment . <hl>", "hl_sentences": "Asian Americans certainly have been subject to their share of racial prejudice , despite the seemingly positive stereotype as the model minority . The model minority stereotype is applied to a minority group that is seen as reaching significant educational , professional , and socioeconomic levels without challenging the existing establishment .", "question": { "cloze_format": "The subordinate group ___ is often referred to as the “model minority\".", "normal_format": "Which subordinate group is often referred to as the “model minority?”", "question_choices": [ "African Americans", "Asian Americans", "White ethnic Americans", "Native Americans" ], "question_id": "fs-id2401704", "question_text": "Which subordinate group is often referred to as the “model minority?”" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 0, "ans_text": "The Bracero Program" }, "bloom": "1", "hl_context": "<hl> For several decades , Mexican workers crossed the long border into America , both legally and illegally , to work in the fields that provided produce for the developing United States . <hl> <hl> Western growers needed a steady supply of labor , and the 1940s and 1950s saw the official federal Bracero Program ( bracero is Spanish for strong-arm ) that offered protection to Mexican guest workers . <hl> Interestingly , 1954 also saw the enactment of “ Operation Wetback , ” which deported thousands of illegal Mexican workers . <hl> From these examples , we can see that the U . S . treatment of immigration from Mexico has been ambivalent at best . <hl> <hl> Not only are there wide differences among the different origins that make up the Hispanic American population , there are also different names for the group itself . <hl> <hl> The 2010 U . S . Census states that “ Hispanic ” or “ Latino ” refers to a person of Cuban , Mexican , Puerto Rican , South or Central American , or other Spanish culture or origin regardless of race . ” There have been some disagreements over whether Hispanic or Latino is the correct term for a group this diverse , and whether it would be better for people to refer to themselves as being of their origin specifically , for example , Mexican American or Dominican American . <hl> This section will compare the experiences of Mexican Americans and Cuban Americans .", "hl_sentences": "For several decades , Mexican workers crossed the long border into America , both legally and illegally , to work in the fields that provided produce for the developing United States . Western growers needed a steady supply of labor , and the 1940s and 1950s saw the official federal Bracero Program ( bracero is Spanish for strong-arm ) that offered protection to Mexican guest workers . From these examples , we can see that the U . S . treatment of immigration from Mexico has been ambivalent at best . Not only are there wide differences among the different origins that make up the Hispanic American population , there are also different names for the group itself . The 2010 U . S . Census states that “ Hispanic ” or “ Latino ” refers to a person of Cuban , Mexican , Puerto Rican , South or Central American , or other Spanish culture or origin regardless of race . ” There have been some disagreements over whether Hispanic or Latino is the correct term for a group this diverse , and whether it would be better for people to refer to themselves as being of their origin specifically , for example , Mexican American or Dominican American .", "question": { "cloze_format": "___ is the federal act or program that was designed to allow more Hispanic American immigration, not block it.", "normal_format": "Which federal act or program was designed to allow more Hispanic American immigration, not block it?", "question_choices": [ "The Bracero Program", "Immigration Reform and Control Act", "Operation Wetback", "SB 1070" ], "question_id": "fs-id1364602", "question_text": "Which federal act or program was designed to allow more Hispanic American immigration, not block it?" }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 2, "ans_text": "Islamophobia" }, "bloom": "1", "hl_context": "<hl> Although the rate of hate crimes against Arab Americans has slowed , Arab Americans are still victims of racism and prejudice . <hl> <hl> Racial profiling has proceeded against Arab Americans as a matter of course since 9/11 . <hl> Particularly when engaged in air travel , being young and Arab-looking is enough to warrant a special search or detainment . <hl> This Islamophobia ( irrational fear of or hatred against Muslims ) does not show signs of abating . <hl> Scholars noted that white domestic terrorists like Timothy McVeigh , who detonated a bomb at an Oklahoma courthouse in 1995 , have not inspired similar racial profiling or hate crimes against whites .", "hl_sentences": "Although the rate of hate crimes against Arab Americans has slowed , Arab Americans are still victims of racism and prejudice . Racial profiling has proceeded against Arab Americans as a matter of course since 9/11 . This Islamophobia ( irrational fear of or hatred against Muslims ) does not show signs of abating .", "question": { "cloze_format": "Many Arab Americans face _______________, especially after 9/11.", "normal_format": "What do many Arab Americans face, especially after 9/11?", "question_choices": [ "racism", "segregation", "Islamophobia", "prejudice" ], "question_id": "fs-id2620520", "question_text": "Many Arab Americans face _______________, especially after 9/11." }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 2, "ans_text": "Because they were forced out of their own countries" }, "bloom": "3", "hl_context": "The Irish immigrants of the same time period were not always as well off financially , especially after the Irish Potato Famine of 1845 . Irish immigrants settled mainly in the cities of the East Coast , where they were employed as laborers and where they faced significant discrimination . German and Irish immigration continued into the late 19th century and earlier 20th century , at which point the numbers for Southern and Eastern European immigrants started growing as well . Italians , mainly from the Southern part of the country , began arriving in large numbers in the 1890s . Eastern European immigrants — people from Russia , Poland , Bulgaria , and Austria-Hungary — started arriving around the same time . <hl> Many of these Eastern Europeans were peasants forced into a hardscrabble existence in their native lands ; political unrest , land shortages , and crop failures drove them to seek better opportunities in the United States . <hl> The Eastern European immigration wave also included Jewish people escaping pogroms ( anti-Jewish uprisings ) of Eastern Europe and the Pale of Settlement in what was then Poland and Russia . <hl> White Ethnic Americans <hl>", "hl_sentences": "Many of these Eastern Europeans were peasants forced into a hardscrabble existence in their native lands ; political unrest , land shortages , and crop failures drove them to seek better opportunities in the United States . White Ethnic Americans", "question": { "cloze_format": "Most white ethnic Americans came to the United States ___.", "normal_format": "Why did most white ethnic Americans come to the United States?", "question_choices": [ "For a better life", "To escape oppression", "Because they were forced out of their own countries", "a and b only" ], "question_id": "fs-id1381364", "question_text": "Why did most white ethnic Americans come to the United States?" }, "references_are_paraphrase": null } ]
11
11.1 Racial, Ethnic, and Minority Groups While many students first entering a sociology classroom are accustomed to conflating the terms “race,” “ethnicity,” and “minority group,” these three terms have distinct meanings for sociologists. The idea of race refers to superficial physical differences that a particular society considers significant, while ethnicity is a term that describes shared culture. And minority groups describe groups that are subordinate, or lacking power in society regardless of skin color or country of origin. For example, in modern U.S. history, the elderly might be considered a minority group due to a diminished status resulting from popular prejudice and discrimination against them. The World Health Organization’s research on elderly maltreatment shows that 10 percent of nursing home staff admit to physically abusing an elderly person in the past year, and 40 percent admit to psychological abuse (2011). As a minority group, the elderly are also subject to economic, social, and workplace discrimination. What Is Race? Historically, the concept of race has changed across cultures and eras, eventually becoming less connected with ancestral and familial ties, and more concerned with superficial physical characteristics. In the past, theorists have posited categories of race based on various geographic regions, ethnicities, skin colors, and more. Their labels for racial groups have connoted regions (Mongolia and the Caucus Mountains, for instance) or denoted skin tones (black, white, yellow, and red, for example). However, this typology of race developed during early racial science has fallen into disuse, and the social construction of race is a far more common way of understanding racial categories. According to this school of thought, race is not biologically identifiable. When considering skin color, for example, the social construction of race perspective recognizes that the relative darkness or fairness of skin is an evolutionary adaptation to the available sunlight in different regions of the world. Contemporary conceptions of race, therefore, which tend to be based on socioeconomic assumptions, illuminate how far removed modern race understanding is from biological qualities. In modern society, some people who consider themselves “white” actually have more melanin (a pigment that determines skin color) in their skin than other people who identify as ”black.” Consider the case of the actress Rashida Jones. She is the daughter of a black man (Quincy Jones) but she does not play a black woman in her television or film roles. In some countries, such as Brazil, class is more important than skin color in determining racial categorization. People with high levels of melanin in their skin may consider themselves "white" if they enjoy a middle-class lifestyle. On the other hand, someone with low levels of melanin in their skin might be assigned the identity of "black" if they have little education or money. The social construction of race is also reflected in the way that names for racial categories change with changing times. It’s worth noting that race, in this sense, is also a system of labeling that provides a source of identity; specific labels fall in and out of favor during different social eras. For example, the category ”negroid,” popular in the 19th century, evolved into the term “negro” by the 1960s, and then this term fell from use and was replaced with “African American.” This latter term was intended to celebrate the multiple identities that a black person might hold, but the word choice is a poor one: it lumps together a large variety of ethnic groups under an umbrella term while excluding others who could accurately be described by the label but who do not meet the spirit of the term. For example, actress Charlize Theron is a blonde-haired, blue-eyed “African American.” She was born in South Africa and later became a U.S. citizen. Is her identity that of an “African American” as most of us understand the term? What Is Ethnicity? Ethnicity is a term that describes shared culture—the practices, values, and beliefs of a group. This might include shared language, religion, and traditions, among other commonalities. Like race, the term ethnicity is difficult to describe and its meaning has changed over time. And like race, individuals may be identified or self-identify to ethnicities in complex, even contradictory, ways. For example, ethnic groups such as Irish, Italian American, Russian, Jewish, and Serbian might all be groups whose members are predominantly included in the racial category “white.” Conversely, the ethnic group British includes citizens from a multiplicity of racial backgrounds: black, white, Asian, and more, plus a variety of race combinations. These examples illustrate the complexity and overlap of these identifying terms. Ethnicity, like race, continues to be an identification method that individuals and institutions use today—whether through the census, affirmative action initiatives, non-discrimination laws, or simply in personal day-to-day relations. What Are Minority Groups? Sociologist Louis Wirth (1945) defined a minority group as “any group of people who, because of their physical or cultural characteristics, are singled out from the others in the society in which they live for differential and unequal treatment, and who therefore regard themselves as objects of collective discrimination.” The term minority connotes discrimination, and in its sociological use, the term subordinate can be used interchangeably with the term minority, while the term dominant is often substituted for the group that’s in the majority. These definitions correlate to the concept that the dominant group is that which holds the most power in a given society, while subordinate groups are those who lack power compared to the dominant group. Note that being a numerical minority is not a characteristic of being a minority group; sometimes larger groups can be considered minority groups due to their lack of power. It is the lack of power that is the predominant characteristic of a minority, or subordinate group. For example, consider Apartheid in South Africa, in which a numerical majority (the black inhabitants of the country) were exploited and oppressed by the white minority. According to Charles Wagley and Marvin Harris (1958), a minority group is distinguished by five characteristics: (1) unequal treatment and less power over their lives, (2) distinguishing physical or cultural traits like skin color or language, (3) involuntary membership in the group, (4) awareness of subordination, and (5) high rate of in-group marriage. Additional examples of minority groups might include the LBGT community, religious practitioners whose faith is not widely practiced where they live, and people with disabilities. Scapegoat theory , developed initially from Dollard’s (1939) Frustration-Aggression theory, suggests that the dominant group will displace their unfocused aggression onto a subordinate group. History has shown us many examples of the scapegoating of a subordinate group. An example from the last century is the way that Adolf Hitler was able to use the Jewish people as scapegoats for Germany’s social and economic problems. In the United States, recent immigrants have frequently been the scapegoat for the nation’s—or an individual’s—woes. Many states have enacted laws to disenfranchise immigrants; these laws are popular because they let the dominant group scapegoat a subordinate group. Multiple Identities Prior to the 20th century, racial intermarriage (referred to as miscegenation) was extremely rare, and in many places, illegal. While the sexual subordination of slaves did result in children of mixed race, these children were usually considered black, and therefore, property. There was no question of multiple racial identities with the possible exception of the Creole. Creole society developed in the port city of New Orleans, where a mixed-race culture grew from French and African inhabitants. Unlike in other parts of the country, “Creoles of color” had greater social, economic, and educational opportunities than most African Americans. Increasingly during the modern era, the removal of miscegenation laws and a trend toward equal rights and legal protection against racism have steadily reduced the social stigma attached to racial exogamy (exogamy refers to marriage outside of one’s core social unit). It is now common for the children of racially mixed parents to acknowledge and celebrate their various ethnic identities. Golfer Tiger Woods, for instance, has Chinese, Thai, African American, Native American, and Dutch heritage; he jokingly refers to his ethnicity as “Cablinasian,” a term he coined to combine several of his ethnic backgrounds. While this is the trend, it is not yet evident in all aspects of our society. For example, the U.S. Census only recently added additional categories for people to identify themselves, such as non-white Hispanic. A growing number of people chose multiple races to describe themselves on the 2010 Census, paving the way for the 2020 Census to provide yet more choices. 11.2 Stereotypes, Prejudice, and Discrimination Stereotypes The terms stereotype, prejudice, discrimination, and racism are often used interchangeably in everyday conversation. But when discussing these terms from a sociological perspective, it is important to define them: stereotypes are oversimplified ideas about groups of people, prejudice refers to thoughts and feelings about those groups, while discrimination refers to actions toward them. Racism is a type of prejudice that involves set beliefs about a specific racial group. As stated above, stereotypes are oversimplified ideas about groups of people. Stereotypes can be based on race, ethnicity, age, gender, sexual orientation—almost any characteristic. They may be positive (usually about one’s own group, such as when women suggest they are less likely to complain about physical pain) but are often negative (usually toward other groups, such as when members of a dominant racial group suggest that a subordinate racial group is stupid or lazy). In either case, the stereotype is a generalization that doesn’t take individual differences into account. Where do stereotypes come from? In fact new stereotypes are rarely created; rather, they are recycled from subordinate groups that have assimilated into society and are reused to describe newly subordinate groups. For example, many stereotypes that are currently used to characterize black people were used earlier in American history to characterize Irish and Eastern European immigrants. Prejudice and Racism Prejudice refers to beliefs, thoughts, feelings, and attitudes that someone holds about a group. A prejudice is not based on experience; instead, it is a prejudgment, originating outside of actual experience. Racism is a type of prejudice that is used to justify the belief that one racial category is somehow superior or inferior to others. The Ku Klux Klan is an example of a racist organization; its members’ belief in white supremacy has encouraged over a century of hate crime and hate speech. Discrimination While prejudice refers to biased thinking , discrimination consists of actions against a group of people. Discrimination can be based on age, religion, health, and other indicators; race-based discrimination and antidiscrimination laws strive to address this set of social problems. Discrimination based on race or ethnicity can take many forms, from unfair housing practices to biased hiring systems. Overt discrimination has long been part of U.S. history. In the late 19th century, it was not uncommon for business owners to hang signs that read, “Help Wanted: No Irish Need Apply.” And of course, southern Jim Crow laws, with their “Whites Only” signs, exemplified overt discrimination that is not tolerated today. However, discrimination cannot be erased from our culture just by enacting laws to abolish it. Even if a magic pill managed to eradicate racism from each individual’s psyche, society itself would maintain it. Sociologist Émile Durkheim calls racism a social fact, meaning that it does not require the action of individuals to continue. The reasons for this are complex and relate to the educational, criminal, economic, and political systems that exist. For example, when a newspaper prints the race of individuals accused of a crime, it may enhance stereotypes of a certain minority. Another example of racist practices is racial steering , in which real estate agents direct prospective homeowners toward or away from certain neighborhoods based on their race. Racist attitudes and beliefs are often more insidious and hard to pin down than specific racist practices. Prejudice and discrimination can overlap and intersect in many ways. To illustrate, here are four examples of how prejudice and discrimination can occur. Unprejudiced nondiscriminators are open-minded, tolerant, and accepting individuals. Unprejudiced discriminators might be those who, unthinkingly, practice sexism in their workplace by not considering females for certain positions that have traditionally been held by men. Prejudiced nondiscriminators are those who hold racist beliefs but don’t act on them, such as a racist store owner who serves minority customers. Prejudiced discriminators include those who actively make disparaging remarks about others or who perpetuate hate crimes. Discrimination also manifests in different ways. The illustrations above are examples of individual discrimination, but other types exist. Institutional discrimination is when a societal system has developed with an embedded disenfranchisement of a group, such as the U.S. military’s historical nonacceptance of minority sexualities as recently experienced surrounding the “don’t ask, don’t tell” policy. Institutional discrimination can also involve the promotion of a group’s status, such as occurs with white privilege. While most white people are willing to admit that non-white people live with a set of disadvantages due to the color of their skin, very few white people are willing to acknowledge the benefits they receive simply by being white. White privilege refers to the fact that dominant groups often accept their experience as the normative (and hence, superior) experience. Failure to recognize this “normality” as race-based is an example of a dominant group institutionalizing racism. Feminist sociologist Peggy McIntosh (1988) described several examples of “white privilege.” For instance, white women can easily find makeup that matches their skin tone. White people can be assured that, most of the time, they will be dealing with authority figures of their own race. How many other examples of white privilege can you think of? The Confederate Flag vs. the First Amendment In January 2006, two girls walked into Burleson High School in Texas carrying purses that displayed large images of Confederate flags. School administrators told the girls that they were in violation of the dress code, which prohibited apparel with inappropriate symbolism or clothing that discriminated based on race. To stay in school, they’d have to have someone pick up their purses or leave them in the office. The girls chose to go home for the day, but proceeded on a path of challenging the action, appealing first to the principal, then to the district superintendent, then to the U.S. District Court, and finally to the Fifth Circuit Court of Appeals. Why did the school ban the purses, and why did they stand behind that ban, even when being sued? Why did the girls, identified anonymously in court documents as A.M. and A.T., pursue such strong legal measures for their right to carry the purses? The issue, of course, is not the purses: it is the Confederate flag that adorns them. This case, A.M. and A.T. v Burleson Independent School District et al. (2009), joins a long line of people and institutions that have fought for their right to display the Confederate flag. In the end, the court sided with the district and noted that the Confederate flag carried symbolism significant enough to disrupt normal school activities. While many young Americans like to believe that racism is mostly in the country’s past, this case illustrates how racism and discrimination are quite alive today. If the Confederate flag is synonymous with slavery, is there any place for its display in modern society? Those who fight for their right to display the flag say that such a display should be covered by the First Amendment: the right to free speech. But others say that the flag is equivalent to hate speech, which is not covered by the First Amendment. Do you think that displaying the Confederate flag should considered free speech or hate speech? 11.3 Theories of Race and Ethnicity Theoretical Perspectives Issues of race and ethnicity can be observed through three major sociological perspectives: functionalism, conflict theory, and symbolic interactionism. As you read through these theories, ask yourself which one makes the most sense, and why. Is more than one theory needed to explain racism, prejudice, stereotypes, and discrimination? Functionalism In the view of functionalism, racial and ethnic inequalities must have served an important function in order to exist as long as they have. This concept, of course, is problematic. How can racism and discrimination contribute positively to society? Sociologists who adhere to the functionalist view argue that racism and discrimination do contribute positively, but only to the dominant group. Historically, it has indeed served dominant groups well to discriminate against subordinate groups. Slavery, of course, was beneficial to slaveholders. Holding racist views can benefit those who want to deny rights and privileges to people they view as inferior to them, but over time, racism harms society. Outcomes of race-based disenfranchisement—such as poverty levels, crime rates, and discrepancies in employment and education opportunities—illustrate the long-term (and clearly negative) results of slavery and racism in American society. Conflict Theory Conflict theories are often applied to inequalities of gender, social class, education, race, and ethnicity. A conflict theory perspective of U.S. history would examine the numerous past and current struggles between the white ruling class and racial and ethnic minorities, noting specific conflicts that have arisen when the dominant group perceived a threat from the minority group. In the late 19th century, the rising power of black Americans after the Civil War resulted in draconian Jim Crow laws that severely limited black political and social power. The years since then have showed a pattern of attempted disenfranchisement, with gerrymandering and voter suppression efforts aimed at predominantly minority neighborhoods. Feminist sociologist Patricia Hill Collins (1990) developed intersection theory , which suggests we cannot separate the effects of race, class, gender, sexual orientation, and other attributes. When we examine race and how it can bring us both advantages and disadvantages, it is important to acknowledge that the way we experience race is shaped, for example, by our gender and class. Multiple layers of disadvantage intersect to create the way we experience race. For example, if we want to understand prejudice, we must understand that the prejudice focused on a white woman because of her gender is very different from the layered prejudice focused on a poor Asian woman, who is affected by stereotypes related to being poor, being a woman, and her ethnic status. Interactionism For symbolic interactionists, race and ethnicity provide strong symbols as sources of identity. In fact, some interactionists propose that the symbols of race, not race itself, are what lead to racism. Famed Interactionist Herbert Blumer (1958) suggested that racial prejudice is formed through interactions between members of the dominant group: Without these interactions, individuals in the dominant group would not hold racist views. These interactions contribute to an abstract picture of the subordinate group that allows the dominant group to support its view of the subordinate group, thus maintaining the status quo. An example of this might be an individual whose beliefs about a particular group are based on images conveyed in popular media, and those are unquestionably believed because the individual has never personally met a member of that group. Culture of Prejudice Culture of prejudice refers to the theory that prejudice is embedded in our culture. We grow up surrounded by images of stereotypes and casual expressions of racism and prejudice. Consider the casually racist imagery on grocery store shelves or the stereotypes that fill popular movies and advertisements. It is easy to see how someone living in the Northeastern United States, who may know no Mexican Americans personally, might gain a stereotyped impression from such sources as Speedy Gonzalez or Taco Bell’s talking Chihuahua. Because we are all exposed to these images and thoughts, it is impossible to know to what extent they have influenced our thought processes. 11.4 Intergroup Relationships Intergroup relations (relationships between different groups of people) range along a spectrum between tolerance and intolerance. The most tolerant form of intergroup relations is pluralism, in which no distinction is made between minority and majority groups, but instead there’s equal standing. At the other end of the continuum are amalgamation, expulsion, and even genocide—stark examples of intolerant intergroup relations. Genocide Genocide , the deliberate annihilation of a targeted (usually subordinate) group, is the most toxic intergroup relationship. Historically, we can see that genocide has included both the intent to exterminate a group and the function of exterminating of a group, intentional or not. Possibly the most well-known case of genocide is Hitler’s attempt to exterminate the Jewish people in the first part of the 20th century. Also known as the Holocaust, the explicit goal of Hitler’s “Final Solution” was the eradication of European Jewry, as well as the decimation of other minority groups such as Catholics, people with disabilities, and homosexuals. With forced emigration, concentration camps, and mass executions in gas chambers, Hitler’s Nazi regime was responsible for the deaths of 12 million people, six million of whom were Jewish. Hitler’s intent was clear, and the high Jewish death toll certainly indicates that Hitler and his regime committed genocide. But how do we understand genocide that is not so overt and deliberate? During the European colonization of the United States, some historians estimate that Native American populations dwindled from approximately 12 million people in the year 1500 to barely 237,000 Native Americans by the year 1900 (Lewy 2004). European settlers coerced American Indians off their own lands, often causing thousands of deaths in forced removals, such as occurred in the Cherokee or Potawatomi Trail of Tears. Settlers also enslaved Native Americans and forced them to give up their religious and cultural practices. But the major cause of Native American death was neither slavery nor war nor forced removal: it was the introduction of European diseases and Indians’ lack of immunity to them. Smallpox, diphtheria, and measles flourished among indigenous American tribes who had no exposure to the diseases and no ability to fight them. Quite simply, these diseases decimated the tribes. How planned this genocide was remains a topic of contention. Some argue that the spread of disease was an unintended effect of conquest, while others believe it was intentional with rumors of smallpox-infected blankets being distributed as “gifts” to tribes. Importantly, genocide is not a just a historical concept, but one practiced today. Recently, ethnic and geographic conflicts in the Darfur region of Sudan have led to hundreds of thousands of deaths. As part of an ongoing land conflict, the Sudanese government and their state-sponsored Janjaweed militia have led a campaign of killing, forced displacement, and systematic rape of Darfuri people. Although a treaty was signed in 2011, the peace is fragile and may break under pressure. Expulsion Expulsion refers to a subordinate group being forced, by a dominant group, to leave a certain area or country. As seen in the examples of the Trail of Tears and the Holocaust, expulsion can be a factor in genocide. However, it can also stand on its own as a destructive group interaction. Expulsion has often occurred historically with an ethnic or racial basis. In the United States, President Franklin D. Roosevelt issued Executive Order 9066 in 1942, after the Japanese government’s attack on Pearl Harbor. The Order authorized the establishment of internment camps for anyone with as little as one-eighth Japanese ancestry (i.e., one great-grandparent who was Japanese). Over 120,000 legal Japanese residents and Japanese American citizens, many of them children, were held in these camps for up to four years, despite the fact that there was never any evidence of collusion or espionage. (In fact, many Japanese Americans continued to demonstrate their loyalty to the United States by serving in the American military during the War.) In the 1990s, the U.S. executive branch issued a formal apology for this expulsion; reparation efforts continue today. Segregation Segregation refers to the physical separation of two groups, particularly in residence, but also in workplace and social functions. It is important to distinguish between de jure segregation (segregation that is enforced by law) and de facto segregation (segregation that occurs without laws but because of other factors). A stark example of de jure segregation is the apartheid movement of South Africa, which existed from 1948 to 1994. Under apartheid, black South Africans were stripped of their civil rights and forcibly relocated to areas that segregated them physically from their white compatriots. Only after decades of degradation, violent uprisings, and international advocacy was apartheid finally abolished. De jure segregation occurred in the United States for many years after the Civil War. During this time, many former Confederate states passed “Jim Crow” laws that required segregated facilities for blacks and whites. These laws were codified in 1896’s landmark Supreme Court case Plessey v. Ferguson , which stated that “separate but equal” facilities were constitutional. For the next five decades, blacks were subjected to legalized discrimination, forced to live, work, and go to school in separate—but unequal —facilities. It wasn’t until 1954 and the Brown v. Board of Education case that the Supreme Court declared that “separate educational facilities are inherently unequal,” thus ending de jure segregation in the United States. De facto segregation, however, cannot be abolished by any court mandate. Segregation is still alive and well in the United States, with different racial or ethnic groups often segregated by neighborhood, borough, or parish. Sociologists use segregation indices to measure racial segregation of different races in different areas. The indices employ a scale from zero to 100, where zero is the most integrated and 100 is the least. In the New York metropolitan area, for instance, the black-white segregation index was 79 for the years 2005–2009. This means that 79 percent of either blacks or whites would have to move in order for each neighborhood to have the same racial balance as the whole metro region (Population Studies Center 2010). Pluralism Pluralism is represented by the ideal of the United States as a “salad bowl”: a great mixture of different cultures where each culture retains its own identity and yet adds to the flavor of the whole. True pluralism is characterized by mutual respect on the part of all cultures, both dominant and subordinate, creating a multicultural environment of acceptance. In reality, true pluralism is a difficult goal to reach. In the United States, the mutual respect required by pluralism is often missing, and the nation’s past pluralist model of a melting pot posits a society where cultural differences aren’t embraced as much as erased. Assimilation Assimilation describes the process by which a minority individual or group gives up its own identity by taking on the characteristics of the dominant culture. In the United States, which has a history of welcoming and absorbing immigrants from different lands, assimilation has been a function of immigration. Most Americans have immigrant ancestors. In relatively recent history, between 1890 and 1920, the United States became home to around 24 million immigrants. In the decades since then, further waves of immigrants have come to these shores and have eventually been absorbed into American culture, sometimes after facing extended periods of prejudice and discrimination. Assimilation may lead to the loss of the minority group’s cultural identity as they become absorbed into the dominant culture, but assimilation has minimal to no impact on the majority group’s cultural identity. Some groups may keep only symbolic gestures of their original ethnicity. For instance, many Irish Americans may celebrate Saint Patrick’s Day, many Hindu Americans enjoy a Diwali festival, and many Mexican Americans may celebrate Cinco de Mayo (a May 5th commemoration of Mexican independence and heritage). However, for the rest of the year, other aspects of their originating culture may be forgotten. Assimilation is antithetical to the “salad bowl” created by pluralism; rather than maintaining their own cultural flavor, subordinate cultures give up their own traditions in order to conform to their new environment. Sociologists measure the degree to which immigrants have assimilated to a new culture with four benchmarks: socioeconomic status, spatial concentration, language assimilation, and intermarriage. When faced with racial and ethnic discrimination, it can be difficult for new immigrants to fully assimilate. Language assimilation, in particular, can be a formidable barrier, limiting employment and educational options and therefore constraining growth in socioeconomic status. Amalgamation Amalgamation is the process by which a minority group and a majority group combine to form a new group. Amalgamation creates the classic “melting pot” analogy; unlike the “salad bowl,” in which each culture retains its individuality, the “melting pot” ideal sees the combination of cultures resulting in a new culture entirely. Amalgamation, also known as miscegenation, is achieved through intermarriage between races. In the United States, anti-miscegenation laws flourished in the South during the Jim Crow era. It wasn’t until 1967’s Loving v. Virginia that the last antimiscegenation law was struck from the books, making these laws unconstitutional. 11.5 Race and Ethnicity in the United States When colonists came to the New World, they found a land that did not need “discovering” since it was already occupied. While the first wave of immigrants came from Western Europe, eventually the bulk of people entering North America were from Northern Europe, then Eastern Europe, then Latin America and Asia. And let us not forget the forced immigration of African slaves. Most of these groups underwent a period of disenfranchisement in which they were relegated to the bottom of the social hierarchy before they managed (for those who could) to achieve social mobility. Today, our society is multicultural, although the extent to which this multiculturality is embraced varies, and the many manifestations of multiculturalism carry significant political repercussions. The sections below will describe how several groups became part of American society, discuss the history of intergroup relations for each faction, and assess each group’s status today. Native Americans The only nonimmigrant ethnic group in the United States, Native Americans were once a large population but by 2010 made up only 0.9 percent of U.S. populace (U.S. Census 2010). Sociology in the Real World Sports Teams with Native American Names The sports world abounds with team names like the Indians, the Warriors, the Braves, and even the Savages and Redskins. These names arise from historically prejudiced views of Native Americans as fierce, brave, and strong savages: attributes that would be beneficial to a sports team, but are not necessarily beneficial to Americans who should be seen as more than just fierce savages. Since the civil rights movement of the 1960s, the National Congress of American Indians (NCAI) has been campaigning against the use of such mascots, asserting that the “warrior savage myth . . . reinforces the racist view that Indians are uncivilized and uneducated and it has been used to justify policies of forced assimilation and destruction of Indian culture” (NCAI Resolution #TUL-05-087 2005). The campaign has met with only limited success. While some teams have changed their names, hundreds of professional, college, and K–12 school teams still have names derived from this stereotype. Another group, American Indian Cultural Support (AICS), is especially concerned with such names at K-12 schools, grades where children should be gaining a fuller and more realistic understanding of Native Americans than such stereotypes supply. What do you think about such names? Should they be allowed or banned? What argument would a symbolic interactionist make on this topic? How and Why They Came The earliest immigrants to America arrived millennia before European immigrants. Dates of the migration are debated with estimates ranging from between 45,000 and 12,000 BCE. It is thought that early Indians migrated to this new land in search of big game to hunt, which they found in huge herds of grazing herbivores in the Americas. Over the centuries and then the millennia, Native American culture blossomed into an intricate web of hundreds of interconnected tribes, each with its own customs, traditions, languages, and religions. History of Intergroup Relations Native American culture prior to European settlement is referred to as Pre-Columbian: that is, prior to the coming of Christopher Columbus in 1492. Mistakenly believing that he had landed in the East Indies, Columbus named the indigenous people “Indians:” a name that has persisted for centuries despite it being a geographical misnomer used to homogenously label over 500 distinct people groups who have their own languages and traditions. The history of intergroup relations between European colonists and Native Americans is a brutal one that most Americans are familiar with. As discussed in the section on genocide, the effect of European settlement of the Americans was to nearly destroy the indigenous population. And although Native Americans’ lack of immunity to European diseases caused the most deaths, overt mistreatment of Native Americans by Europeans was equally devastating. From the first Spanish colonists to the French, English, and Dutch who followed, European settlers took what land they wanted, expanding across the continent at will. If indigenous people tried to retain their stewardship of the land, Europeans fought them off with superior weapons. A key element of this issue is the indigenous view of land and land ownership. Most tribes considered the earth a living entity whose resources they were stewards of, the concepts of land ownership and conquest didn’t exist in Native American society. Europeans’ domination of the Americas was indeed a conquest; one scholar points out that Native Americans are the only minority group in the United States whose subordination occurred purely through conquest by the dominant group (Marger 1993). After the establishment of the United States government, discrimination against Native Americans was codified and formalized in a series of laws intended to subjugate them and keep them from gaining any power. Some of the most impactful laws are as follows: The Indian Removal Act of 1930 forced the relocation of any native tribes east of the Mississippi River to lands west of the river. The Indian Appropriation Acts funded further removals and declared that no Indian tribe could be recognized as an independent nation, tribe, or power with which the American government would have to make treaties. This made it even easier for the U.S. government to take land it wanted. The Dawes Act of 1887 reversed the policy of isolating Native Americans on reservations, instead forcing them onto individual properties that were intermingled with white settlers, thereby reducing their capacity for power as a group. Native American culture was further eroded by the establishment of Indian boarding schools in the late 19th century. These schools, run by both Christian missionaries and the United States government, had the express purpose of “civilizing” Native American children and assimilating them into white society. The boarding schools were located off-reservation to ensure that children were separated from their families and culture. Schools forced children to cut their hair, speak English, and practice Christianity. Physical and sexual abuses were rampant for decades; only in 1987 did the Bureau of Indian Affairs issue a policy on sexual abuse in boarding schools. Some scholars argue that many of the problems that Native Americans face today result from almost a century of mistreatment at these boarding schools. Current Status The eradication of Native American culture continued until the 1960s, when Native Americans were able to participate in and benefit from the civil rights movement. The Indian Civil Rights Act of 1968 guaranteed Indian tribes most of the rights of the United States Bill of Rights. New laws like the Indian Self-Determination Act of 1975 and the Education Assistance Act of the same year recognized tribal governments and gave them more power. Indian boarding schools have dwindled to only a few, and Native American cultural groups are striving to preserve and maintain old traditions to keep them from being lost forever. However, Native Americans (some of whom now wished to be called American Indians so as to avoid the “savage” connotations of the term “native”) still suffer the effects of centuries of degradation. Long-term poverty, inadequate education, cultural dislocation, and high rates of unemployment contribute to Native American populations falling to the bottom of the economic spectrum. Native Americans also suffer disproportionately with lower life expectancies than most groups in the United States. African Americans As discussed in the section on race, the term African American can be a misnomer for many individuals. Many people with dark skin may have their more recent roots in Europe or the Caribbean, seeing themselves as Dominican American or Dutch American. Further, actual immigrants from Africa may feel that they have more of a claim to the term African American than those who are many generations removed from ancestors who originally came to this country. This section will focus on the experience of the slaves who were transported from Africa to the United States, and their progeny. How and Why They Came If Native Americans are the only minority group whose subordinate status occurred by conquest, African Americans are the exemplar minority group in the United States whose ancestors did not come here by choice. A Dutch sea captain brought the first Africans to the Virginia colony of Jamestown in 1619 and sold them as indentured servants. This was not an uncommon practice for either blacks or whites, and indentured servants were in high demand. For the next century, black and white indentured servants worked side by side. But the growing agricultural economy demanded greater and cheaper labor, and by 1705, Virginia passed the slave codes declaring that any foreign-born non-Christian could be a slave, and that slaves were considered property. The next 150 years saw the rise of American slavery, with black Africans being kidnapped from their own lands and shipped to the New World on the trans-Atlantic journey known as the Middle Passage. Once in the Americas, the black population grew until American-born blacks outnumbered those born in Africa. But colonial (and later, American) slave codes declared that the child of a slave was a slave, so the slave class was created. By 1869, the slave trade was internal in the United States, with slaves being bought and sold across state lines like livestock. History of Intergroup Relations There is no starker illustration of the dominant-subordinate group relationship than that of slavery. In order to justify their severely discriminatory behavior, slaveholders and their supporters had to view blacks as innately inferior. Slaves were denied even the most basic rights of citizenship, a crucial factor for slaveholders and their supporters. Slavery poses an excellent example of conflict theory’s perspective on race relations; the dominant group needed complete control over the subordinate group in order to maintain its power. Whippings, executions, rapes, denial of schooling and health care were all permissible and widely practiced. Slavery eventually became an issue over which the nation divided into geographically and ideologically distinct factions, leading to the Civil War. And while the abolition of slavery on moral grounds was certainly a catalyst to war, it was not the only driving force. Students of American history will know that the institution of slavery was crucial to the Southern economy, whose production of crops like rice, cotton, and tobacco relied on the virtually limitless and cheap labor that slavery provided. In contrast, the North didn’t benefit economically from slavery, resulting in an economic disparity tied to racial/political issues. A century later, the civil rights movement was characterized by boycotts, marches, sit-ins, and freedom rides: demonstrations by a subordinate group that would no longer willingly submit to domination. The major blow to America’s formally institutionalized racism was the Civil Rights Act of 1964. This Act, which is still followed today, banned discrimination based on race, color, religion, sex, or national origin. Some sociologists, however, would argue that institutionalized racism persists. Current Status Although government-sponsored, formalized discrimination against African Americans has been outlawed, true equality does not yet exist. The National Urban League’s 2011 Equality Index reports that blacks’ overall equality level with whites has dropped in the past year, from 71.5 percent to 71.1 percent in 2010. The Index , which has been published since 2005, notes a growing trend of increased inequality with whites, especially in the areas of unemployment, insurance coverage, and incarceration. Blacks also trail whites considerably in the areas of economics, health, and education. To what degree do racism and prejudice contribute to this continued inequality? The answer is complex. 2008 saw the election of this country’s first African American president: Barack Hussein Obama. Despite being popularly identified as black, we should note that President Obama is of a mixed background that is equally white, and although all presidents have been publicly mocked at times (Gerald Ford was depicted as a klutz, Bill Clinton as someone who could not control his libido), a startling percentage of the critiques of Obama have been based on his race. The most blatant of these was the controversy over his birth certificate, where the “birther” movement questioned his citizenship and right to hold office. Although blacks have come a long way from slavery, the echoes of centuries of disempowerment are still evident. Asian Americans Like many groups this section discusses, Asian Americans represent a great diversity of cultures and backgrounds. The experience of a Japanese American whose family has been in the United States for three generations will be drastically different from a Laotian American who has only been in the U.S. for a few years. This section primarily discusses Chinese, Japanese, and Vietnamese immigrants and shows the differences between their experiences. How and Why They Came The national and ethnic diversity of Asian American immigration history is reflected in the variety of their experiences in joining American society. Asian immigrants have come to the United States in waves, at different times, and for different reasons. The first Asian immigrants to come to the United States in the mid-19th century were Chinese. These immigrants were primarily men whose intention was to work for several years in order to earn incomes to support their families in China. Their main destination was the American West, where the Gold Rush was drawing people with its lure of abundant money. The construction of the Transcontinental Railroad was underway at this time, and the Central Pacific section hired thousands of migrant Chinese men to complete the laying of rails across the rugged Sierra Nevada mountain range. Chinese men also engaged in other manual labor like mining and agricultural work. The work was grueling and underpaid, but like many immigrants, they persevered. Japanese immigration began in the 1880s, on the heels of the Chinese Exclusion Act of 1882. Many Japanese immigrants came to Hawaii to participate in the sugar industry; others came to the mainland, especially to California. Unlike the Chinese, however, the Japanese had a strong government that negotiated with the United States government to ensure the well-being of their immigrants. Japanese men were able to bring their wives and families to the United States, and were thus able to produce second- and third-generation Japanese Americans more quickly than their Chinese counterparts. The most recent large-scale Asian immigration came from Korea and Vietnam and largely took place during the second half of the 20th century. While Korean immigration has been fairly gradual, Vietnamese immigration occurred primarily post-1975, after the fall of Saigon and the establishment of restrictive communist policies in Vietnam. Whereas many Asian immigrants came to the United States to seek better economic opportunities, Vietnamese immigrants came as political refugees, seeking asylum from harsh conditions in their homeland. The Refugee Act of 1980 helped them to find a place to settle in the United States. History of Intergroup Relations Chinese immigration came to an abrupt end with the Chinese Exclusion Act of 1882. This act was a result of anti-Chinese sentiment burgeoned by a depressed economy and loss of jobs. White workers blamed Chinese migrants for taking jobs, and the passage of the Act meant the number of Chinese workers decreased. Chinese men did not have the funds to return to China or to bring their families to America, so they remained physically and culturally segregated in the Chinatowns of large cities. Later legislation, the Immigration Act of 1924, further curtailed Chinese immigration. The Act included the race-based National Origins Act, which was aimed at keeping American ethnic stock as undiluted as possible by reducing “undesirable” immigrants. It was not until after the Immigration and Nationality Act of 1965 that Chinese immigration again increased and many Chinese families were reunited. Although Japanese Americans have deep, long-reaching roots in the U.S., their history here has not always been smooth. The California Alien Land Law of 1913 was aimed at them and other Asian immigrants, and it prohibited aliens from owning land. An even uglier action was the Japanese internment camps of World War II, discussed earlier as an illustration of expulsion. Current Status Asian Americans certainly have been subject to their share of racial prejudice, despite the seemingly positive stereotype as the model minority. The model minority stereotype is applied to a minority group that is seen as reaching significant educational, professional, and socioeconomic levels without challenging the existing establishment. This stereotype is typically applied to Asian groups in the United States, and it can result in unrealistic expectations, putting a stigma on members of this group that do not meet the expectations. Stereotyping all Asians as smart and capable can also lead to a lack of much-needed government assistance and to educational and professional discrimination. Hispanic Americans Like the individuals comprising many “groups,” Hispanic Americans have a wide range of backgrounds and nationalities. According to the 2010 U.S. Census, about 75 percent of the respondents who identify as Hispanic report being of Mexican, Puerto Rican, or Cuban origin. Of the total Hispanic group, 60 percent reported as Mexican, 44 percent reported as Cuban, and nine percent reported as Puerto Rican. Remember that the U.S. Census allows people to report as being more than one ethnicity. Not only are there wide differences among the different origins that make up the Hispanic American population, there are also different names for the group itself. The 2010 U.S. Census states that “Hispanic” or “Latino” refers to a person of Cuban, Mexican, Puerto Rican, South or Central American, or other Spanish culture or origin regardless of race.” There have been some disagreements over whether Hispanic or Latino is the correct term for a group this diverse, and whether it would be better for people to refer to themselves as being of their origin specifically, for example, Mexican American or Dominican American. This section will compare the experiences of Mexican Americans and Cuban Americans. How and Why They Came Mexican Americans form the largest Hispanic subgroup and also the oldest. Mexican migration to the United States started in the early 1900s in response to the need for cheap agricultural labor. Mexican migration was often circular; workers would stay for a few years, and then go back to Mexico with more money than they could have made in their country of origin. The length of Mexico’s shared border with the United States has made immigration easier than for many other immigrant groups. Cuban Americans are the second-largest Hispanic subgroup, and their history is quite different from that of Mexican Americans. The main wave of Cuban immigration to the United States started after Fidel Castro came to power in 1959 and reached its crest with the Mariel boatlift in 1980. Castro’s Cuban Revolution ushered in an era of communism that continues to this day. To avoid having their assets seized by the government, many wealthy and educated Cubans migrated north, generally to the Miami area. History of Intergroup Relations For several decades, Mexican workers crossed the long border into America, both legally and illegally, to work in the fields that provided produce for the developing United States. Western growers needed a steady supply of labor, and the 1940s and 1950s saw the official federal Bracero Program ( bracero is Spanish for strong-arm ) that offered protection to Mexican guest workers. Interestingly, 1954 also saw the enactment of “Operation Wetback,” which deported thousands of illegal Mexican workers. From these examples, we can see that the U.S. treatment of immigration from Mexico has been ambivalent at best. Sociologist Douglas Massey (2006) suggests that although the average standard of living in Mexico may be lower in the United States, it is not so low as to make permanent migration the goal of most Mexicans. However, the strengthening of the border that began with 1986’s Immigration Reform and Control Act has made one-way migration the rule for most Mexicans. Massey argues that the rise of illegal one-way immigration of Mexicans is a direct outcome of the law that was intended to reduce it. Cuban Americans, perhaps because of their relative wealth and education level at the time of immigration, have fared better than many immigrants. Further, because they were fleeing a Communist country, they were given refugee status and offered protection and social services. The Cuban Migration Agreement of 1995 has curtailed legal immigration from Cuba, leading many Cubans to try to immigrate illegally by boat. According to a 2009 report from the Congressional Research Service, the U.S. government applies a “wet foot/dry foot” policy toward Cuban immigrants; Cubans who are intercepted while still at sea will be returned to Cuba, while those who reach the shore will be permitted to stay in the United States. Current Status Mexican Americans, especially those who are here illegally, are at the center of a national debate about immigration. Myers (2007) observes that no other minority group (except the Chinese) has immigrated to the United States in such an environment of illegality. He notes that in some years, three times as many Mexican immigrants may have entered the United States illegally as those who arrived legally. It should be noted that this is due to enormous disparity of economic opportunity on two sides of an open border, not because of any inherent inclination to break laws. In his report, “Measuring Immigrant Assimilation in the United States,” Jacob Vigdor (2008) states that Mexican immigrants experience relatively low rates of economic and civil assimilation. He further suggests that “the slow rates of economic and civic assimilation set Mexicans apart from other immigrants, and may reflect the fact that the large numbers of Mexican immigrants residing in the United States illegally have few opportunities to advance themselves along these dimensions.” By contrast, Cuban Americans are often seen as a model minority group within the larger Hispanic group. Many Cubans had higher socioeconomic status when they arrived in this country, and their anti-Communist agenda has made them welcome refugees to this country. In south Florida, especially, Cuban Americans are active in local politics and professional life. As with Asian Americans, however, being a model minority can mask the issue of powerlessness that these minority groups face in U.S. society. Social Policy and Debate Arizona’s Senate Bill 1070 As both legal and illegal immigrants, and with high population numbers, Mexican Americans are often the target of stereotyping, racism, and discrimination. A harsh example of this is in Arizona, where a new stringent immigration law—known as SB 1070 (for Senate Bill 1070)—has caused a nationwide controversy. The law requires that during a lawful stop, detention, or arrest, Arizona police officers must establish the immigration status of anyone they suspect may be here illegally. The law makes it a crime for individuals to fail to have documents confirming their legal status, and it gives police officers the right to detain people they suspect may be in the country illegally. To many, the most troublesome aspect of this law is the latitude it affords police officers in terms of whose citizenship they may question. Having “reasonable suspicion that the person is an alien who is unlawfully present in the United States” is reason enough to demand immigration papers (Senate Bill 1070 2010). Critics say this law will encourage racial profiling (the illegal practice of law enforcement using race as a basis for suspecting someone of a crime), making it hazardous to be caught “Driving While Brown,” a takeoff on the legal term Driving While Intoxicated (DWI) or the slang reference of “Driving While Black.” Driving While Brown refers to the likelihood of getting pulled over just for being nonwhite. SB 1070 has been the subject of many lawsuits, from parties as diverse as Arizona police officers, the American Civil Liberties Union, and even the federal government, which is suing on the basis of Arizona contradicting federal immigration laws (ACLU 2011). The future of SB 1070 is uncertain, but many other states have tried or are trying to pass similar measures. Do you think such measures are appropriate? Arab Americans If ever a category was hard to define, the various groups lumped under the name “Arab American” is it. After all, Hispanic Americans or Asian Americans are so designated because of their counties of origin. But for Arab Americans, their country of origin—Arabia—has not existed for centuries. In addition, Arab Americans represent all religious practices, despite there being a stereotype of them as Islamic. As Myers (2007) asserts, not all Arabs are Muslim, and not all Muslims are Arab, complicating the stereotype of what it means to be an Arab American. Geographically, the Arab region comprises the Middle East and parts of northern Africa. People whose ancestry lies in that area or who speak primarily Arabic may consider themselves Arabs. The U.S. Census has struggled with the issue of Arab identity. The 2010 Census, as in previous years, did not offer an “Arab” box to check under the question of race. Individuals who want to be counted as Arabs had to check the box for “Some other race” and then write in their race. However, when the Census data is tallied, they will be marked as white. This is problematic, however, denying Arab Americans opportunities for federal assistance. Why They Came The first Arab immigrants came to this country in the late 19th and early 20th century. They were predominantly Syrian, Lebanese, and Jordanian Christians, and they came to escape persecution and to make a better life. These early immigrants and their descendants, who were more likely to think of themselves as Syrian or Lebanese than Arab, represent almost half of the Arab American population today (Myers 2007). Restrictive immigration policies from the 1920s until 1965 curtailed all immigration, but Arab immigration since 1965 has been steady. Immigrants from this time period have been more likely to be Muslim and more highly educated, escaping political unrest and looking for better opportunities. History of Intergroup Relations Relations between Arab Americans and the dominant majority have been marked by mistrust, misinformation, and deeply entrenched beliefs. Helen Samhan of the Arab American Institute suggests that Arab-Israeli conflicts in the 1970s contributed significantly to cultural and political anti-Arab sentiment in the United States (2001). The United States has historically supported the State of Israel, while some Middle Eastern countries deny the existence of the Israeli state. Disputes over these issues have involved Egypt, Syria, Iraq, Jordan, Lebanon, and Palestine. As is often the case with stereotyping and prejudice, the actions of extremists come to define the entire group, regardless of the fact that most U.S. citizens with ties to the Middle Eastern community condemn terrorist actions, as do most inhabitants of the Middle East. Would it be fair to judge all Catholics by the events of the Inquisition? Of course, the United States was deeply affected by the events of September 11, 2001. This event has left a deep scar on the American psyche, and it has fortified anti-Arab sentiment for a large percentage of Americans. In the first month after 9/11, hundreds of hate crimes were perpetrated against people who looked like they might be of Arab descent. Current Status Although the rate of hate crimes against Arab Americans has slowed, Arab Americans are still victims of racism and prejudice. Racial profiling has proceeded against Arab Americans as a matter of course since 9/11. Particularly when engaged in air travel, being young and Arab-looking is enough to warrant a special search or detainment. This Islamophobia (irrational fear of or hatred against Muslims) does not show signs of abating. Scholars noted that white domestic terrorists like Timothy McVeigh, who detonated a bomb at an Oklahoma courthouse in 1995, have not inspired similar racial profiling or hate crimes against whites. White Ethnic Americans As we have seen, there is no minority group that fits easily in a category or that can be described simply. While sociologists believe that individual experiences can often be understood in light of their social characteristics (such as race, class, or gender), we must balance this perspective with awareness that no two individuals’ experiences are alike. Making generalizations can lead to stereotypes and prejudice. The same is true for white ethnic Americans, who come from diverse backgrounds and have had a great variety of experiences. In this section, we will focus on German, Irish, Italian, and Eastern European immigrants. Why They Came White ethnic Europeans formed the second and third great waves of immigration, from the early 19th century to the mid-20th century. They joined a newly minted United States that was primarily made up of white Protestants from England. While most immigrants came searching for a better life, their experiences were not all the same. The first major influx of European immigrants came from Germany and Ireland, starting in the 1820s. Germans came both for economic opportunity and to escape political unrest and military conscription, especially after the Revolutions of 1848. Many German immigrants of this period were political refugees: liberals who wanted to escape from an oppressive government. They were well-off enough to make their way inland, and they formed heavily German enclaves in the Midwest that exist to this day. The Irish immigrants of the same time period were not always as well off financially, especially after the Irish Potato Famine of 1845. Irish immigrants settled mainly in the cities of the East Coast, where they were employed as laborers and where they faced significant discrimination. German and Irish immigration continued into the late 19th century and earlier 20th century, at which point the numbers for Southern and Eastern European immigrants started growing as well. Italians, mainly from the Southern part of the country, began arriving in large numbers in the 1890s. Eastern European immigrants—people from Russia, Poland, Bulgaria, and Austria-Hungary—started arriving around the same time. Many of these Eastern Europeans were peasants forced into a hardscrabble existence in their native lands; political unrest, land shortages, and crop failures drove them to seek better opportunities in the United States. The Eastern European immigration wave also included Jewish people escaping pogroms (anti-Jewish uprisings) of Eastern Europe and the Pale of Settlement in what was then Poland and Russia. History of Intergroup Relations In a broad sense, German immigrants were not victimized to the same degree as many of the other subordinate groups this section discusses. While they may not have been welcomed with open arms, they were able to settle in enclaves and establish roots. A notable exception to this was during the lead up to World War I and through World War II, when anti-German sentiment was virulent. Irish immigrants, many of whom were very poor, were more of an underclass than the Germans. In Ireland, the English had oppressed the Irish for centuries, eradicating their language and culture and discriminating against their religion (Catholicism). Although the Irish had a larger population than the English, they were a subordinate group. This dynamic reached into the new world, where Anglo Americans saw Irish immigrants as a race apart: dirty, lacking ambition, and suitable for only the most menial jobs. In fact, Irish immigrants were subject to criticism identical to that with which the dominant group characterized African Americans. By necessity, Irish immigrants formed tight communities segregated from their Anglo neighbors. The later wave of immigrants from Southern and Eastern Europe was also subject to intense discrimination and prejudice. In particular, the dominant group—which now included second- and third-generation Germans and Irish—saw Italian immigrants as the dregs of Europe and worried about the purity of the American race (Myers 2007). Italian immigrants lived in segregated slums in Northeastern cities, and in some cases were even victims of violence and lynchings similar to what African Americans endured. They worked harder and were paid less than other workers, often doing the dangerous work that other laborers were reluctant to take on. Current Status The U.S. Census from 2008 shows that 16.5 percent of respondents reported being of German descent: the largest group in the country. For many years, German Americans endeavored to maintain a strong cultural identity, but they are now culturally assimilated into the dominant culture. There are now more Irish Americans in the United States than there are Irish in Ireland. One of the country’s largest cultural groups, Irish Americans have slowly achieved acceptance and assimilation into the dominant group. Myers (2007) states that Italian Americans’ cultural assimilation is “almost complete, but with remnants of ethnicity.” The presence of “Little Italy” neighborhoods—originally segregated slums where Italians congregated in the 19th century—exist today. While tourists flock to the saints’ festivals in Little Italies, most Italian Americans have moved to the suburbs at the same rate as other white groups.
introduction_to_sociology
Learning Objectives 7.1 Deviance and Control Define deviance and explain the nature of deviant behavior Differentiate between methods of social control 7.2 Theoretical Perspectives on Deviance Describe the functionalist view of deviance in society through four sociologist’s theories Explain how conflict theory understands deviance and crime in society Describe the symbolic interactionist approach to deviance, including labeling and other theories 7.3 Crime and the Law Identify and differentiate between different types of crimes Evaluate U.S. crime statistics Understand the three branches of the U.S. criminal justice system Introduction to Deviance, Crime, and Social Control Philip Hudson entered Morehouse College at age 19 wearing men’s jeans and long hair tied back in dreadlocks. “The first day I got to campus, I was a boy,” Philip recalled a few years later. He said he was “trying to be this masculine boy, real cool and real quiet.” By the end of his sophomore year, Philip had swapped his jeans for skirts and found himself the target of a strong backlash (King 2010). Morehouse College made national news for its response to the teen’s lifestyle, establishing a schoolwide ban on the wearing of women’s clothing by men (Chen 2010). Morehouse College, an all-male college in Atlanta, Georgia, has a prestigious history. Established in 1867 as a place of higher learning for former slaves, Morehouse is the alma mater of great leaders such as “Dr. Martin Luther King, Jr. and Howard Thurman, and celebrities such as Samuel L. Jackson and Spike Lee” (Mungin 2009). The sense of revolution is what brought Philip to Morehouse, a place where he hoped he could be himself. After a difficult upbringing where his gendered-ness resulted in abuse and rape, he realized that he identified as a female and wanted to express that aspect of his person. He began taking female hormones to start his biological transition to the female sex. Although Philip initially halted his treatment once he began college, he soon found others like himself. At Morehouse, he met Diamond Poulin, a student who defined himself as a man who felt comfortable in women’s clothes. Joined by a handful of others, Philip and Diamond donned skirts, high heels, and other traditionally female attire on campus in an attempt to be themselves. They were jeered at and ridiculed—even attacked. Then came the school’s shocking decision in late 2009. The new rules, titled the “Appropriate Attire Policy,” banned cross-dressing anywhere on the campus grounds. Those who broke the rules were not allowed to attend class unless they changed their clothing, and multiple transgressions led to disciplinary action and suspension. Diamond left Morehouse that fall, but returned once in the spring to visit his friends. He found himself escorted off campus by school security for violating the dress code. Philip remained at Morehouse for another year before leaving because of stress. He now plans to resume his studies at a larger university in Florida. What he’s most looking forward to is walking around in public without being verbally attacked. “They’ll stare,” Philip says with resignation, “but I’m used to that” (King 2010).
[ { "answer": { "ans_choice": 3, "ans_text": "Deviance is socially defined." }, "bloom": "1", "hl_context": "What , exactly , is deviance ? And what is the relationship between deviance and crime ? <hl> As Philip Hudson found out , some behaviors , such as wearing clothes of the opposite sex , can be deviant in certain places , criminal in some places , and perfectly acceptable elsewhere . <hl> <hl> According to sociologist William Graham Sumner , deviance is a violation of established contextual , cultural , or social norms , whether folkways , mores , or codified law ( 1906 ) . <hl> <hl> It can be as minor as picking one ’ s nose in public or as major as committing murder . <hl> Although the word “ deviance ” has a negative connotation in everyday language , sociologists recognize that deviance is not necessarily bad ( Schoepflin 2011 ) . In fact , from a structural functionalist perspective , one of the positive contributions of deviance is that it fosters social change . For example , during the U . S . civil rights movement , Rosa Parks violated social norms when she refused to move to the “ black section ” of the bus , and the Little Rock Nine broke customs of segregation to attend an Arkansas public school .", "hl_sentences": "As Philip Hudson found out , some behaviors , such as wearing clothes of the opposite sex , can be deviant in certain places , criminal in some places , and perfectly acceptable elsewhere . According to sociologist William Graham Sumner , deviance is a violation of established contextual , cultural , or social norms , whether folkways , mores , or codified law ( 1906 ) . It can be as minor as picking one ’ s nose in public or as major as committing murder .", "question": { "cloze_format": "Deviance is best described as ___ .", "normal_format": "Which of the following best describes how deviance is defined?", "question_choices": [ "Deviance is defined by federal, state, and local laws.", "Deviance’s definition is determined by one’s religion.", "Deviance occurs whenever someone else is harmed by an action.", "Deviance is socially defined." ], "question_id": "fs-id1370636", "question_text": "Which of the following best describes how deviance is defined?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 1, "ans_text": "An act of deviance" }, "bloom": null, "hl_context": "Although deviance is a violation of social norms , it ’ s not always punishable , and it ’ s not necessarily bad . Crime , on the other hand , is a behavior that violates official law and is punishable through formal sanctions . Walking to class backwards is a deviant behavior . Driving with a blood alcohol percentage over the state ’ s limit is a crime . <hl> Like other forms of deviance , however , ambiguity exists concerning what constitutes a crime and whether all crimes are , in fact , “ bad ” and deserve punishment . <hl> <hl> For example , during the 1960s , civil rights activists often violated laws intentionally as part of their effort to bring about racial equality . <hl> <hl> In hindsight , we recognize that the laws that deemed many of their actions crimes — for instance , Rosa Parks taking a seat in the “ whites only ” section of the bus — were inconsistent with social equality . <hl> What , exactly , is deviance ? And what is the relationship between deviance and crime ? As Philip Hudson found out , some behaviors , such as wearing clothes of the opposite sex , can be deviant in certain places , criminal in some places , and perfectly acceptable elsewhere . According to sociologist William Graham Sumner , deviance is a violation of established contextual , cultural , or social norms , whether folkways , mores , or codified law ( 1906 ) . It can be as minor as picking one ’ s nose in public or as major as committing murder . Although the word “ deviance ” has a negative connotation in everyday language , sociologists recognize that deviance is not necessarily bad ( Schoepflin 2011 ) . <hl> In fact , from a structural functionalist perspective , one of the positive contributions of deviance is that it fosters social change . <hl> <hl> For example , during the U . S . civil rights movement , Rosa Parks violated social norms when she refused to move to the “ black section ” of the bus , and the Little Rock Nine broke customs of segregation to attend an Arkansas public school . <hl>", "hl_sentences": "Like other forms of deviance , however , ambiguity exists concerning what constitutes a crime and whether all crimes are , in fact , “ bad ” and deserve punishment . For example , during the 1960s , civil rights activists often violated laws intentionally as part of their effort to bring about racial equality . In hindsight , we recognize that the laws that deemed many of their actions crimes — for instance , Rosa Parks taking a seat in the “ whites only ” section of the bus — were inconsistent with social equality . In fact , from a structural functionalist perspective , one of the positive contributions of deviance is that it fosters social change . For example , during the U . S . civil rights movement , Rosa Parks violated social norms when she refused to move to the “ black section ” of the bus , and the Little Rock Nine broke customs of segregation to attend an Arkansas public school .", "question": { "cloze_format": "During the civil rights movement, Rosa Parks and other black protestors spoke out against segregation by refusing to sit at the back of the bus. This is an example of ________.", "normal_format": "During the civil rights movement, Rosa Parks and other black protestors spoke out against segregation by refusing to sit at the back of the bus. Which is this an example of?", "question_choices": [ "An act of social control", "An act of deviance", "A social norm", "Criminal mores" ], "question_id": "fs-id1303155", "question_text": "During the civil rights movement, Rosa Parks and other black protestors spoke out against segregation by refusing to sit at the back of the bus. This is an example of ________." }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 0, "ans_text": "formal sanctions" }, "bloom": null, "hl_context": "As you learned previously , all societies have informal and formal ways of maintaining social control . <hl> Within these systems of norms , societies have legal codes that maintain formal social control through laws , which are rules adopted and enforced by a political authority . <hl> Those who violate these rules incur negative formal sanctions . Normally , punishments are relative to the degree of the crime and the importance to society of the value underlying the law . As we will see , however , there are other factors that influence criminal sentencing .", "hl_sentences": "Within these systems of norms , societies have legal codes that maintain formal social control through laws , which are rules adopted and enforced by a political authority .", "question": { "cloze_format": "Societies practice social control to maintain ________.", "normal_format": "Societies practice social control to maintain what?", "question_choices": [ "formal sanctions", "social order", "cultural deviance", "sanction labeling" ], "question_id": "fs-id3135713", "question_text": "Societies practice social control to maintain ________." }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 1, "ans_text": "A senator" }, "bloom": "1", "hl_context": "<hl> In his book The Power Elite ( 1956 ) , sociologist C . Wright Mills described the existence of what he dubbed the power elite , a small group of wealthy and influential people at the top of society who hold the power and resources . <hl> <hl> Wealthy executives , politicians , celebrities , and military leaders often have access to national and international power , and in some cases , their decisions affect everyone in society . <hl> Because of this , the rules of society are stacked in favor of a privileged few who manipulate them to stay on top . It is these people who decide what is criminal and what is not , and the effects are often felt most by those who have little power . Mills ’ theories explain why celebrities such as Chris Brown and Paris Hilton , or once-powerful politicians such as Eliot Spitzer and Tom DeLay , can commit crimes with little or no legal retribution .", "hl_sentences": "In his book The Power Elite ( 1956 ) , sociologist C . Wright Mills described the existence of what he dubbed the power elite , a small group of wealthy and influential people at the top of society who hold the power and resources . Wealthy executives , politicians , celebrities , and military leaders often have access to national and international power , and in some cases , their decisions affect everyone in society .", "question": { "cloze_format": "According to C. Wright Mills, the person that is most likely to be a member of the power elite is ___.", "normal_format": "According to C. Wright Mills, which of the following people is most likely to be a member of the power elite?", "question_choices": [ "A war veteran", "A senator", "A professor", "A mechanic" ], "question_id": "fs-id1366105", "question_text": "According to C. Wright Mills, which of the following people is most likely to be a member of the power elite?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 0, "ans_text": "A community where neighbors don’t know each other very well" }, "bloom": null, "hl_context": "<hl> Developed by researchers at the University of Chicago in the 1920s and 1930s , social disorganization theory asserts that crime is most likely to occur in communities with weak social ties and the absence of social control . <hl> An individual who grows up in a poor neighborhood with high rates of drug use , violence , teenage delinquency , and deprived parenting is more likely to become a criminal than an individual from a wealthy neighborhood with a good school system and families who are involved positively in the community .", "hl_sentences": "Developed by researchers at the University of Chicago in the 1920s and 1930s , social disorganization theory asserts that crime is most likely to occur in communities with weak social ties and the absence of social control .", "question": { "cloze_format": "According to social disorganization theory, crime is most likely to occur in ___.", "normal_format": "According to social disorganization theory, crime is most likely to occur where?", "question_choices": [ "A community where neighbors don’t know each other very well", "A neighborhood with mostly elderly citizens", "A city with a large minority population ", "A college campus with students who are very competitive" ], "question_id": "fs-id909380", "question_text": "According to social disorganization theory, crime is most likely to occur where?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 3, "ans_text": "wealth" }, "bloom": "1", "hl_context": "<hl> The theory of Shaw and McKay has been further tested and expounded upon by Robert Sampson and Byron Groves ( 1989 ) . <hl> <hl> They found that poverty , ethnic diversity , and family disruption in given localities had a strong positive correlation with social disorganization . <hl> They also determined that social disorganization was , in turn , associated with high rates of crime and delinquency — or deviance . Recent studies Sampson conducted with Lydia Bean ( 2006 ) revealed similar findings . High rates of poverty and single-parent homes correlated with high rates of juvenile violence . Cultural deviance theory suggests that conformity to the prevailing cultural norms of lower-class society causes crime . <hl> Researchers Clifford Shaw and Henry McKay ( 1942 ) studied crime patterns in Chicago in the early 1900s . <hl> <hl> They found that violence and crime were at their worst in the middle of the city and gradually decreased the farther one traveled from the urban center toward the suburbs . <hl> Shaw and McKay noticed that this pattern matched the migration patterns of Chicago citizens . New immigrants , many of them poor and lacking knowledge of English , lived in neighborhoods inside the city . As the urban population expanded , wealthier people moved to the suburbs , leaving behind the less privileged .", "hl_sentences": "The theory of Shaw and McKay has been further tested and expounded upon by Robert Sampson and Byron Groves ( 1989 ) . They found that poverty , ethnic diversity , and family disruption in given localities had a strong positive correlation with social disorganization . Researchers Clifford Shaw and Henry McKay ( 1942 ) studied crime patterns in Chicago in the early 1900s . They found that violence and crime were at their worst in the middle of the city and gradually decreased the farther one traveled from the urban center toward the suburbs .", "question": { "cloze_format": "Shaw and McKay found that crime is linked primarily to ________.", "normal_format": "Shaw and McKay found that crime is linked primarily to which of the following?", "question_choices": [ "power", "master status", "family values", "wealth" ], "question_id": "fs-id1824438", "question_text": "Shaw and McKay found that crime is linked primarily to ________." }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 1, "ans_text": "Because his fame protects him from retribution" }, "bloom": "4", "hl_context": "<hl> In his book The Power Elite ( 1956 ) , sociologist C . Wright Mills described the existence of what he dubbed the power elite , a small group of wealthy and influential people at the top of society who hold the power and resources . <hl> <hl> Wealthy executives , politicians , celebrities , and military leaders often have access to national and international power , and in some cases , their decisions affect everyone in society . <hl> Because of this , the rules of society are stacked in favor of a privileged few who manipulate them to stay on top . It is these people who decide what is criminal and what is not , and the effects are often felt most by those who have little power . <hl> Mills ’ theories explain why celebrities such as Chris Brown and Paris Hilton , or once-powerful politicians such as Eliot Spitzer and Tom DeLay , can commit crimes with little or no legal retribution . <hl>", "hl_sentences": "In his book The Power Elite ( 1956 ) , sociologist C . Wright Mills described the existence of what he dubbed the power elite , a small group of wealthy and influential people at the top of society who hold the power and resources . Wealthy executives , politicians , celebrities , and military leaders often have access to national and international power , and in some cases , their decisions affect everyone in society . Mills ’ theories explain why celebrities such as Chris Brown and Paris Hilton , or once-powerful politicians such as Eliot Spitzer and Tom DeLay , can commit crimes with little or no legal retribution .", "question": { "cloze_format": "According to the concept of the power elite, the reason a celebrity such as Charlie Sheen would commit a crime is ___ .", "normal_format": "According to the concept of the power elite, why would a celebrity such as Charlie Sheen commit a crime?", "question_choices": [ "Because his parents committed similar crimes", "Because his fame protects him from retribution", "Because his fame disconnects him from society", "Because he is challenging socially accepted norms" ], "question_id": "fs-id1674578", "question_text": "According to the concept of the power elite, why would a celebrity such as Charlie Sheen commit a crime?" }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 0, "ans_text": "The offender has been labeled deviant by society and has accepted a new master status." }, "bloom": "3", "hl_context": "Sometimes , in more extreme cases , primary deviance can morph into secondary deviance . <hl> Secondary deviance occurs when a person ’ s self-concept and behavior begin to change after his or her actions are labeled as deviant by members of society . <hl> <hl> The person may begin to take on and fulfill the role of a “ deviant ” as an act of rebellion against the society that has labeled that individual as such . <hl> For example , consider a high school student who often cuts class and gets into fights . The student is reprimanded frequently by teachers and school staff , and soon enough , he develops a reputation as a “ troublemaker . ” As a result , the student starts acting out even more and breaking more rules ; he has adopted the “ troublemaker ” label and embraced this deviant identity . <hl> Secondary deviance can be so strong that it bestows a master status on an individual . <hl> A master status is a label that describes the chief characteristic of an individual . Some people see themselves primarily as doctors , artists , or grandfathers . Others see themselves as beggars , convicts , or addicts .", "hl_sentences": "Secondary deviance occurs when a person ’ s self-concept and behavior begin to change after his or her actions are labeled as deviant by members of society . The person may begin to take on and fulfill the role of a “ deviant ” as an act of rebellion against the society that has labeled that individual as such . Secondary deviance can be so strong that it bestows a master status on an individual .", "question": { "cloze_format": "A convicted sexual offender is released on parole and arrested two weeks later for repeated sexual crimes. Labeling theory would explain that ___ .", "normal_format": "A convicted sexual offender is released on parole and arrested two weeks later for repeated sexual crimes. How would labeling theory explain this?", "question_choices": [ "The offender has been labeled deviant by society and has accepted a new master status.", "The offender has returned to his old neighborhood and so reestablished his former habits.", "The offender has lost the social bonds he made in prison and feels disconnected from society.", "The offender is poor and responding to the different cultural values that exist in his community." ], "question_id": "fs-id2916966", "question_text": "A convicted sexual offender is released on parole and arrested two weeks later for repeated sexual crimes. How would labeling theory explain this?" }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 2, "ans_text": "Primary; does not" }, "bloom": "1", "hl_context": "Sociologist Edwin Lemert expanded on the concepts of labeling theory , identifying two types of deviance that affect identity formation . <hl> Primary deviance is a violation of norms that does not result in any long-term effects on the individual ’ s self-image or interactions with others . <hl> Speeding is a deviant act , but receiving a speeding ticket generally does not make others view you as a bad person , nor does it alter your own self-concept . Individuals who engage in primary deviance still maintain a feeling of belonging in society and are likely to continue to conform to norms in the future .", "hl_sentences": "Primary deviance is a violation of norms that does not result in any long-term effects on the individual ’ s self-image or interactions with others .", "question": { "cloze_format": "______ deviance is a violation of norms that ______result in a person being labeled a deviant.", "normal_format": "What deviance is a violation of norms? And does it result in a person being labeled a deviant? ", "question_choices": [ "Secondary; does not", "Negative; does", "Primary; does not", "Primary; may or may not" ], "question_id": "fs-id2732159", "question_text": "______ deviance is a violation of norms that ______result in a person being labeled a deviant." }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 0, "ans_text": "Embezzlement" }, "bloom": null, "hl_context": "When we think of crime , we often picture street crime , or offenses committed by ordinary people against other people or organizations , usually in public spaces . An often overlooked category is corporate crime , or crime committed by white-collar workers in a business environment . <hl> Embezzlement , insider trading , and identity theft are all types of corporate crime . <hl> Although these types of offenses rarely receive the same amount of media coverage as street crimes , they can be far more damaging . The current economic recession in the United States is the ultimate result of a financial collapse triggered by corporate crime .", "hl_sentences": "Embezzlement , insider trading , and identity theft are all types of corporate crime .", "question": { "cloze_format": "___ is an example of corporate crime.", "normal_format": "Which of the following is an example of corporate crime?", "question_choices": [ "Embezzlement", "Larceny", "Assault", "Burglary" ], "question_id": "fs-id2885117", "question_text": "Which of the following is an example of corporate crime?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 2, "ans_text": "violent crime" }, "bloom": null, "hl_context": "Not all crimes are given equal weight . Society generally socializes its members to view certain crimes as more severe than others . For example , most people would consider murdering someone to be far worse than stealing a wallet and would expect a murderer to be punished more severely than a thief . In modern American society , crimes are classified as one of two types based on their severity . <hl> Violent crimes ( also known as “ crimes against a person ” ) are based on the use of force or the threat of force . <hl> <hl> Rape , murder , and armed robbery fall under this category . <hl> Nonviolent crimes involve the destruction or theft of property , but do not use force or the threat of force . Because of this , they are also sometimes called “ property crimes . ” Larceny , car theft , and vandalism are all types of nonviolent crimes . If you use a crowbar to break into a car , you are committing a nonviolent crime ; if you mug someone with the crowbar , you are committing a violent crime .", "hl_sentences": "Violent crimes ( also known as “ crimes against a person ” ) are based on the use of force or the threat of force . Rape , murder , and armed robbery fall under this category .", "question": { "cloze_format": "Spousal abuse is an example of a ________.", "normal_format": "What is spousal abuse an example of?", "question_choices": [ "street crime", "corporate crime", "violent crime", "nonviolent crime" ], "question_id": "fs-id1003194", "question_text": "Spousal abuse is an example of a ________." }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 0, "ans_text": "Rates of violent and nonviolent crimes are decreasing." }, "bloom": "1", "hl_context": "While neither of these publications can take into account all of the crimes committed in the country , some general trends may be noted . <hl> Crime rates were on the rise after 1960 , but following an all-time high in the 1980s and 1990s , rates of violent and non-violent crimes once again started to decline . <hl>", "hl_sentences": "Crime rates were on the rise after 1960 , but following an all-time high in the 1980s and 1990s , rates of violent and non-violent crimes once again started to decline .", "question": { "cloze_format": "The situation that best describes crime trends in the United States is that ___.", "normal_format": "Which of the following situations best describes crime trends in the United States?", "question_choices": [ "Rates of violent and nonviolent crimes are decreasing.", "Rates of violent crimes are decreasing, but there are more nonviolent crimes now than ever before.", "Crime rates have skyrocketed since the 1970s due to lax corrections laws.", "Rates of street crime have gone up, but corporate crime has gone down." ], "question_id": "fs-id2071330", "question_text": "Which of the following situations best describes crime trends in the United States?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 1, "ans_text": "The NCVS may be unable to reach important groups, such as those without phones." }, "bloom": "1", "hl_context": "<hl> Though the NCVS is a critical source of statistical information , disadvantages exist . <hl> <hl> “ Non-response , ” or a victim ’ s failure to participate in the survey or a particular question , is among them . <hl> <hl> Inability to contact important demographics , such as those who don ’ t have access to phones or frequently relocate , also skews the data . <hl> For those who participate , memory issues can be problematic for the data sets . Some victims ’ recollection of the crimes can be inaccurate or simply forgotten over time ( Cantor and Lynch 2000 ) .", "hl_sentences": "Though the NCVS is a critical source of statistical information , disadvantages exist . “ Non-response , ” or a victim ’ s failure to participate in the survey or a particular question , is among them . Inability to contact important demographics , such as those who don ’ t have access to phones or frequently relocate , also skews the data .", "question": { "cloze_format": "A disadvantage of the National Crime Victimization Survey (NCVS) is that ___.", "normal_format": "What is a disadvantage of the National Crime Victimization Survey (NCVS)?", "question_choices": [ "The NCVS doesn’t include demographic data, such as age or gender.", "The NCVS may be unable to reach important groups, such as those without phones.", "The NCVS doesn’t address the relationship between the criminal and the victim.", "The NCVS only includes information collected by police officers." ], "question_id": "fs-id2913595", "question_text": "What is a disadvantage of the National Crime Victimization Survey (NCVS)?" }, "references_are_paraphrase": null } ]
7
7.1 Deviance and Control What, exactly, is deviance? And what is the relationship between deviance and crime? As Philip Hudson found out, some behaviors, such as wearing clothes of the opposite sex, can be deviant in certain places, criminal in some places, and perfectly acceptable elsewhere. According to sociologist William Graham Sumner, deviance is a violation of established contextual, cultural, or social norms, whether folkways, mores, or codified law (1906). It can be as minor as picking one’s nose in public or as major as committing murder. Although the word “deviance” has a negative connotation in everyday language, sociologists recognize that deviance is not necessarily bad (Schoepflin 2011). In fact, from a structural functionalist perspective, one of the positive contributions of deviance is that it fosters social change. For example, during the U.S. civil rights movement, Rosa Parks violated social norms when she refused to move to the “black section” of the bus, and the Little Rock Nine broke customs of segregation to attend an Arkansas public school. “What is deviant behavior?” cannot be answered in a straightforward manner. Whether an act is labeled deviant or not depends on many factors, including location, audience, and the individual committing the act (Becker 1963). Listening to your iPod on the way to class is considered acceptable behavior. Listening to your iPod during your 2 o’clock sociology lecture is considered rude. Listening to your iPod when on the witness stand before a judge may cause you to be held in contempt of court, and consequently fined or jailed. As norms vary across culture and time, it makes sense that notions of deviance change also. Fifty years ago, public schools in the United States had strict dress codes that, among other stipulations, often banned women from wearing pants to class. Today, it’s socially acceptable for women to wear pants, but less so for men to wear skirts. In a time of war, acts usually considered morally reprehensible, such as taking the life of another, may actually be rewarded. Whether an act is deviant or not depends on society’s response to that act. Why I Drive a Hearse When sociologist Todd Schoepflin ran into his childhood friend Bill, he was shocked to see him driving a hearse. A professionally trained researcher, Schoepflin wondered what effect driving a hearse had on his friend and what effect it might have on others on the road. Would using such a vehicle for everyday errands be considered deviant by most people? Schoepflin interviewed Bill, curious first to know why he drove such an unconventional car. Bill had simply been on the lookout for a reliable winter car; on a tight budget, he searched used car ads and stumbled upon one for the hearse. The car ran well and the price was right, so he bought it. Bill admitted that others’ reactions to the car had been mixed. His parents were appalled and he received odd stares from his coworkers. A mechanic once refused to work on it, stating that it was “a dead person machine.” On the whole, however, Bill received mostly positive reactions. Strangers gave him a thumbs-up on the highway and stopped him in parking lots to chat about his car. His girlfriend loved it, his friends wanted to take it tailgating, and people offered to buy it. Could it be that driving a hearse isn’t really so deviant after all? Schoepflin theorized that, although viewed as outside conventional norms, driving a hearse is such a mild form of deviance that it actually becomes a mark of distinction. Conformists find the choice of vehicle intriguing or appealing, while nonconformists see a fellow oddball to whom they can relate. As one of Bill’s friends remarked, “Every guy wants to own a unique car like this and you can certainly pull it off.” Such anecdotes remind us that although deviance is often viewed as a violation of norms, it’s not always viewed in a negative light (Schoepflin 2011). Social Control When a person violates a social norm, what happens? A driver caught speeding can receive a speeding ticket. A student who wears a bathrobe to class gets a warning from a professor. An adult belching loudly is avoided. All societies practice social control , the regulation and enforcement of norms. The underlying goal of social control is to maintain social order , an arrangement of practices and behaviors on which society’s members base their daily lives. Think of social order as an employee handbook and social control as a manager. When a worker violates a workplace guideline, the manager steps in to enforce the rules. The means of enforcing rules are known as sanctions . Sanctions can be positive as well as negative. Positive sanctions are rewards given for conforming to norms. A promotion at work is a positive sanction for working hard. Negative sanctions are punishments for violating norms. Being arrested is a punishment for shoplifting. Both types of sanctions play a role in social control. Sociologists also classify sanctions as formal or informal. Although shoplifting, a form of social deviance, may be illegal, there are no laws dictating the proper way to scratch one’s nose. That doesn’t mean picking your nose in public won’t be punished; instead, you will encounter informal sanctions . Informal sanctions emerge in face-to-face social interactions. For example, wearing flip-flops to an opera or swearing loudly in church may draw disapproving looks or even verbal reprimands, whereas behavior that is seen as positive—such as helping an old man carry grocery bags across the street—may receive positive informal reactions, such as a smile or pat on the back. Formal sanctions , on the other hand, are ways to officially recognize and enforce norm violations. If a student violates her college’s code of conduct, for example, she might be expelled. Someone who speaks inappropriately to the boss could be fired. Someone who commits a crime may be arrested or imprisoned. On the positive side, a soldier who saves a life may receive an official commendation. The table below shows the relationship between different types of sanctions. Informal Formal Positive An expression of thanks A promotion at work Negative An angry comment A parking fine Table 7.1 Informal/Formal Sanctions Formal and informal sanctions may be positive or negative. Informal sanctions arise in social interactions, whereas formal sanctions officially enforce norms. 7.2 Theoretical Perspectives on Deviance Why does deviance occur? How does it affect a society? Since the early days of sociology, scholars have developed theories attempting to explain what deviance and crime mean to society. These theories can be grouped according to the three major sociological paradigms: functionalism, symbolic interactionism, and conflict theory. Functionalism Sociologists who follow the functionalist approach are concerned with how the different elements of a society contribute to the whole. They view deviance as a key component of a functioning society. Strain theory, social disorganization theory, and cultural deviance theory represent three functionalist perspectives on deviance in society. Émile Durkheim: The Essential Nature of Deviance Émile Durkheim believed that deviance is a necessary part of a successful society. One way deviance is functional, he argued, is that it challenges people’s present views (1893). For instance, when black students across the United States participated in “sit-ins” during the civil rights movement, they challenged society’s notions of segregation. Moreover, Durkheim noted, when deviance is punished, it reaffirms currently held social norms, which also contributes to society (1893). Seeing a student given detention for skipping class reminds other high schoolers that playing hooky isn’t allowed and that they, too, could get detention. Robert Merton: Strain Theory Sociologist Robert Merton agreed that deviance is an inherent part of a functioning society, but he expanded on Durkheim’s ideas by developing strain theory , which notes that access to socially acceptable goals plays a part in determining whether a person conforms or deviates. From birth, we’re encouraged to achieve the “American Dream” of financial success. A woman who attends business school, receives her MBA, and goes on to make a million-dollar income as CEO of a company is said to be a success. However, not everyone in our society stands on equal footing. A person may have the socially acceptable goal of financial success but lack a socially acceptable way to reach that goal. According to Merton’s theory, an entrepreneur who can’t afford to launch his own company may be tempted to embezzle from his employer for start-up funds. Merton defined five ways that people respond to this gap between having a socially accepted goal but no socially accepted way to pursue it. Conformity : Those who conform choose not to deviate. They pursue their goals to the extent that they can through socially accepted means. Innovation : Those who innovate pursue goals they cannot reach through legitimate means by instead using criminal or deviant means. Ritualism : People who ritualize lower their goals until they can reach them through socially acceptable ways. These members of society focus on conformity rather than attaining a distant dream. Retreatism : Others retreat and reject society’s goals and means. Some beggars and street people have withdrawn from society’s goal of financial success. Rebellion : A handful of people rebel, replacing a society’s goals and means with their own. Terrorists or freedom fighters look to overthrow a society’s goals through socially unacceptable means. Social Disorganization Theory Developed by researchers at the University of Chicago in the 1920s and 1930s, social disorganization theory asserts that crime is most likely to occur in communities with weak social ties and the absence of social control. An individual who grows up in a poor neighborhood with high rates of drug use, violence, teenage delinquency, and deprived parenting is more likely to become a criminal than an individual from a wealthy neighborhood with a good school system and families who are involved positively in the community. Social disorganization theory points to broad social factors as the cause of deviance. A person isn’t born a criminal, but becomes one over time, often based on factors in his or her social environment. Research into social disorganization theory can greatly influence public policy. For instance, studies have found that children from disadvantaged communities who attend preschool programs that teach basic social skills are significantly less likely to engage in criminal activity. Clifford Shaw and Henry McKay: Cultural Deviance Theory Cultural deviance theory suggests that conformity to the prevailing cultural norms of lower-class society causes crime. Researchers Clifford Shaw and Henry McKay (1942) studied crime patterns in Chicago in the early 1900s. They found that violence and crime were at their worst in the middle of the city and gradually decreased the farther one traveled from the urban center toward the suburbs. Shaw and McKay noticed that this pattern matched the migration patterns of Chicago citizens. New immigrants, many of them poor and lacking knowledge of English, lived in neighborhoods inside the city. As the urban population expanded, wealthier people moved to the suburbs, leaving behind the less privileged. Shaw and McKay concluded that socioeconomic status correlated to race and ethnicity resulted in a higher crime rate. The mix of cultures and values created a smaller society with different ideas of deviance, and those values and ideas were transferred from generation to generation. The theory of Shaw and McKay has been further tested and expounded upon by Robert Sampson and Byron Groves (1989). They found that poverty, ethnic diversity, and family disruption in given localities had a strong positive correlation with social disorganization. They also determined that social disorganization was, in turn, associated with high rates of crime and delinquency—or deviance. Recent studies Sampson conducted with Lydia Bean (2006) revealed similar findings. High rates of poverty and single-parent homes correlated with high rates of juvenile violence. Conflict Theory Conflict theory looks to social and economic factors as the causes of crime and deviance. Unlike functionalists, conflict theorists don’t see these factors as positive functions of society, but as evidence of inequality in the system. They also challenge social disorganization theory and control theory, arguing that both ignore racial and socioeconomic issues and oversimplify social trends (Akers 1991). Conflict theorists also look for answers to the correlation of gender and race with wealth and crime. Karl Marx: An Unequal System Conflict theory is derived greatly from the work of sociologist, philosopher, and revolutionary Karl Marx. Marx divided the general population into two rigid social groups: the proletariat and the bourgeois. The bourgeois are a small and wealthy segment of society who controls the means of production, while the proletariat is composed of the workers who rely on those means of production for employment and survival. By centralizing these vital resources into few hands, the bourgeois also has the means to control the way society is regulated—from laws, to government, to other authority agencies—which gives the bourgeois the opportunity to maintain and expand their power in society. Though Marx spoke little of deviance, his ideas created the foundation for conflict theorists who study the intersection of deviance and crime with wealth and power. C. Wright Mills: The Power Elite In his book The Power Elite (1956), sociologist C. Wright Mills described the existence of what he dubbed the power elite , a small group of wealthy and influential people at the top of society who hold the power and resources. Wealthy executives, politicians, celebrities, and military leaders often have access to national and international power, and in some cases, their decisions affect everyone in society. Because of this, the rules of society are stacked in favor of a privileged few who manipulate them to stay on top. It is these people who decide what is criminal and what is not, and the effects are often felt most by those who have little power. Mills’ theories explain why celebrities such as Chris Brown and Paris Hilton, or once-powerful politicians such as Eliot Spitzer and Tom DeLay, can commit crimes with little or no legal retribution. Crime and Social Class While crime is often associated with the underprivileged, crimes committed by the wealthy and powerful remain an under-punished and costly problem within society. The FBI reported that victims of burglary, larceny, and motor vehicle theft lost a total of $15.3 billion dollars in 2009 (FB1 2010). In comparison, when Bernie Madoff was arrested in 2008, the US Securities and Exchange Commission reported that the estimated losses of his financial Ponzi scheme fraud were close to $50 billion (SEC 2009). This imbalance based on class power is also found within US criminal law. In the 1980s, the use of crack cocaine (cocaine in its purest form) quickly became an epidemic sweeping the country’s poorest urban communities. Its pricier counterpart, cocaine, was associated with upscale users and was a drug of choice for the wealthy. The legal implications of being caught by authorities with crack versus cocaine were starkly different. In 1986, federal law mandated that being caught in possession of 50 grams of crack was punishable by a 10-year prison sentence. An equivalent prison sentence for cocaine possession, however, required possession of 5,000 grams. In other words, the sentencing disparity was 1 to 100 (New York Times Editorial Staff 2011). This inequality in the severity of punishment for crack versus cocaine paralleled the unequal social class of respective users. A conflict theorist would note that those in society who hold the power are also the ones who make the laws concerning crime. In doing so, they make laws that will benefit them, while the powerless classes who lack the resources to make such decisions suffer the consequences. The crack-cocaine punishment disparity remained until 2010, when President Obama signed the Fair Sentencing Act, which decreased the disparity to 1 to 18 (The Sentencing Project 2010). Symbolic Interactionism Symbolic interactionism is a theoretical approach that can be used to explain how societies and/or social groups come to view behaviors as deviant or conventional. Labeling theory, differential association, social disorganization theory, and control theory fall within the realm of symbolic interactionism. Labeling Theory Although all of us violate norms from time to time, few people would consider themselves deviant. Those who do, however, have often been labeled “deviant” by society and have gradually come to believe it themselves. Labeling theory examines the ascribing of a deviant behavior to another person by members of society. Thus, what is considered deviant is determined not so much by the behaviors themselves or the people who commit them, but by the reactions of others to these behaviors. As a result, what is considered deviant changes over time and can vary significantly across cultures. Sociologist Edwin Lemert expanded on the concepts of labeling theory, identifying two types of deviance that affect identity formation. Primary deviance is a violation of norms that does not result in any long-term effects on the individual’s self-image or interactions with others. Speeding is a deviant act, but receiving a speeding ticket generally does not make others view you as a bad person, nor does it alter your own self-concept. Individuals who engage in primary deviance still maintain a feeling of belonging in society and are likely to continue to conform to norms in the future. Sometimes, in more extreme cases, primary deviance can morph into secondary deviance. Secondary deviance occurs when a person’s self-concept and behavior begin to change after his or her actions are labeled as deviant by members of society. The person may begin to take on and fulfill the role of a “deviant” as an act of rebellion against the society that has labeled that individual as such. For example, consider a high school student who often cuts class and gets into fights. The student is reprimanded frequently by teachers and school staff, and soon enough, he develops a reputation as a “troublemaker.” As a result, the student starts acting out even more and breaking more rules; he has adopted the “troublemaker” label and embraced this deviant identity. Secondary deviance can be so strong that it bestows a master status on an individual. A master status is a label that describes the chief characteristic of an individual. Some people see themselves primarily as doctors, artists, or grandfathers. Others see themselves as beggars, convicts, or addicts. Social Policy and Debate The Right to Vote Before she lost her job as an administrative assistant, Leola Strickland postdated and mailed a handful of checks for amounts ranging from $90 to $500. By the time she was able to find a new job, the checks had bounced, and she was convicted of fraud under Mississippi law. Strickland pleaded guilty to a felony charge and repaid her debts; in return, she was spared from serving prison time. Strickland appeared in court in 2001. More than ten years later, she is still feeling the sting of her sentencing. Why? Because Mississippi is one of 12 states in the United States that bans convicted felons from voting (ProCon 2011). To Strickland, who said she had always voted, the news came as a great shock. She isn’t alone. Some 5.3 million people in the United States are currently barred from voting because of felony convictions (ProCon 2009). These individuals include inmates, parolees, probationers, and even people who have never been jailed, such as Leola Strickland. Under the Fourteenth Amendment, states are allowed to deny voting privileges to individuals who have participated in “rebellion or other crime” (Krajick 2004). Although there are no federally mandated laws on the matter, most states practice at least one form of felony disenfranchisement . At present, it’s estimated that approximately 2.4 percent of the possible voting population is disfranchised, that is, lacking the right to vote (ProCon 2011). Is it fair to prevent citizens from participating in such an important process? Proponents of disfranchisement laws argue that felons have a debt to pay to society. Being stripped of their right to vote is part of the punishment for criminal deeds. Such proponents point out that voting isn’t the only instance in which ex-felons are denied rights; state laws also ban released criminals from holding public office, obtaining professional licenses, and sometimes even inheriting property (Lott and Jones 2008). Opponents of felony disfranchisement in the United States argue that voting is a basic human right and should be available to all citizens regardless of past deeds. Many point out that felony disfranchisement has its roots in the 1800s, when it was used primarily to block black citizens from voting. Even nowadays, these laws disproportionately target poor minority members, denying them a chance to participate in a system that, as a social conflict theorist would point out, is already constructed to their disadvantage (Holding 2006). Those who cite labeling theory worry that denying deviants the right to vote will only further encourage deviant behavior. If ex-criminals are disenfranchised from voting, are they being disenfranchised from society? Edwin Sutherland: Differential Association In the early 1900s, sociologist Edwin Sutherland sought to understand how deviant behavior developed among people. Since criminology was a young field, he drew on other aspects of sociology including social interactions and group learning (Laub 2006). His conclusions established differential association theory , stating that individuals learn deviant behavior from those close to them who provide models of and opportunities for deviance. According to Sutherland, deviance is less a personal choice and more a result of differential socialization processes. A tween whose friends are sexually active is more likely to view sexual activity as acceptable. Sutherland’s theory may account for why crime is multigenerational. A longitudinal study beginning in the 1960s found that the best predictor of antisocial and criminal behavior in children was whether their parents had been convicted of a crime (Todd and Jury 1996). Children who were younger than 10 when their parents were convicted were more likely than other children to engage in spousal abuse and criminal behavior by their early thirties. Even when taking socioeconomic factors such as dangerous neighborhoods, poor school systems, and overcrowded housing into consideration, researchers found that parents were the main influence on the behavior of their offspring (Todd and Jury 1996). Travis Hirschi: Control Theory Continuing with an examination of large social factors, control theory states that social control is directly affected by the strength of social bonds and that deviance results from a feeling of disconnection from society. Individuals who believe they are a part of society are less likely to commit crimes against it. Travis Hirschi (1969) identified four types of social bonds that connect people to society: Attachment measures our connections to others. When we are closely attached to people, we worry about their opinions of us. People conform to society’s norms in order to gain approval (and prevent disapproval) from family, friends, and romantic partners. Commitment refers to the investments we make in the community. A well-respected local businesswoman who volunteers at her synagogue and is a member of the neighborhood block organization has more to lose from committing a crime than a woman who doesn’t have a career or ties to the community. Similarly, levels of involvement , or participation in socially legitimate activities, lessen a person’s likelihood of deviance. Children who are members of little league baseball teams have fewer family crises. The final bond, belief , is an agreement on common values in society. If a person views social values as beliefs, he or she will conform to them. An environmentalist is more likely to pick up trash in a park because a clean environment is a social value to him (Hirschi 1969). 7.3 Crime and the Law On December 16, 2011, 20-year-old Colton Harris-Moore was sentenced to seven years in prison by an Island County judge after pleading guilty to dozens of charges including burglary, fraud, and identity theft. Harris-Moore, dubbed the “Barefoot Bandit,” spent two years evading the police by means of transportation theft and squatting, frequently leaving a trail of bare footprints in his wake (Johnson 2011). "Colton's very pleased (with the sentence)," his attorney John Henry Browne told the New York Times . "He was expecting the worst." The son of an alcoholic mother, Harris-Moore’s life was filled with physical and verbal abuse, and a series of convict boyfriends frequently inhabited the Harris-Moore home. After dropping out of school in the ninth grade, Harris Moore’s crimes increased in severity. His antics gained worldwide media attention after he began stealing and successfully piloting planes, though he’d had no aviation training. When authorities caught him, he was driving a stolen boat off the coast of the Bahamas (Yardley 2010). "This case is a tragedy in many ways,” said Judge Churchill, “but it's a triumph of the human spirit in other ways. I could have been reading about the history of a mass murderer. I could have been reading about a drug abusive, alcoholic young man. That is the triumph of Colton Harris-Moore: He has survived" (Johnson 2011). Though the judge’s ruling was largely sympathetic, Harris-Moore had immediate regrets. "Let me put it this way,” said his attorney. “He wishes he had done things a little differently in his life" (CNN News Wire Staff 2010). Although deviance is a violation of social norms, it’s not always punishable, and it’s not necessarily bad. Crime , on the other hand, is a behavior that violates official law and is punishable through formal sanctions. Walking to class backwards is a deviant behavior. Driving with a blood alcohol percentage over the state’s limit is a crime. Like other forms of deviance, however, ambiguity exists concerning what constitutes a crime and whether all crimes are, in fact, “bad” and deserve punishment. For example, during the 1960s, civil rights activists often violated laws intentionally as part of their effort to bring about racial equality. In hindsight, we recognize that the laws that deemed many of their actions crimes—for instance, Rosa Parks taking a seat in the “whites only” section of the bus—were inconsistent with social equality. As you learned previously, all societies have informal and formal ways of maintaining social control. Within these systems of norms, societies have legal codes that maintain formal social control through laws, which are rules adopted and enforced by a political authority. Those who violate these rules incur negative formal sanctions. Normally, punishments are relative to the degree of the crime and the importance to society of the value underlying the law. As we will see, however, there are other factors that influence criminal sentencing. Types of Crimes Not all crimes are given equal weight. Society generally socializes its members to view certain crimes as more severe than others. For example, most people would consider murdering someone to be far worse than stealing a wallet and would expect a murderer to be punished more severely than a thief. In modern American society, crimes are classified as one of two types based on their severity. Violent crimes (also known as “crimes against a person”) are based on the use of force or the threat of force. Rape, murder, and armed robbery fall under this category. Nonviolent crimes involve the destruction or theft of property, but do not use force or the threat of force. Because of this, they are also sometimes called “property crimes.” Larceny, car theft, and vandalism are all types of nonviolent crimes. If you use a crowbar to break into a car, you are committing a nonviolent crime; if you mug someone with the crowbar, you are committing a violent crime. When we think of crime, we often picture street crime , or offenses committed by ordinary people against other people or organizations, usually in public spaces. An often overlooked category is corporate crime , or crime committed by white-collar workers in a business environment. Embezzlement, insider trading, and identity theft are all types of corporate crime. Although these types of offenses rarely receive the same amount of media coverage as street crimes, they can be far more damaging. The current economic recession in the United States is the ultimate result of a financial collapse triggered by corporate crime. An often-debated third type of crime is victimless crime . These are called victimless because the perpetrator is not explicitly harming another person. As opposed to battery or theft, which clearly have a victim, a crime like drinking a beer at age 20 or selling a sexual act do not result in injury to anyone other than the individual who engages in them, although they are illegal. While some claim acts like these are victimless, others argue that they actually do harm society. Prostitution may foster abuse toward women by clients or pimps. Drug use may increase the likelihood of employee absences. Such debates highlight how the deviant and criminal nature of actions develops through ongoing public discussion. Big Picture Hate Crimes On the evening of October 3, 2010, a 17-year-old boy from the Bronx was abducted by a group of young men from his neighborhood and taken to an abandoned row house. After being beaten, the boy admitted he was gay. His attackers seized his partner and beat him as well. Both victims were drugged, sodomized, and forced to burn one another with cigarettes. When questioned by police, the ringleader of the crime explained that the victims were gay and “looked like [they] liked it” (Wilson and Baker 2010). Attacks based on a person’s race, religion, or other characteristics are known as hate crimes . Hate crimes in the United States evolved from the time of early European settlers and their violence toward Native Americans. Such crimes weren’t investigated until the early 1900s, when the Ku Klux Klan began to draw national attention for its activities against blacks and other groups. The term “hate crime,” however, didn’t become official until the1980s (Federal Bureau of Investigations 2011). An average of 195,000 Americans fall victim to hate crimes each year, but fewer than five percent ever report the crime (FBI 2010). The majority of hate crimes are racially motivated, but many are based on religious (especially anti-Semitic) prejudice (FBI 2010). After incidents like the murder of Matthew Shepard in Wyoming in 1998 and the tragic suicide of Rutgers University student Tyler Clementi in 2010, there has been a growing awareness of hate crimes based on sexual orientation. Crime Statistics What crimes are people in the United States most likely to commit, and who is most likely to commit them? To understand criminal statistics, you must first understand how these statistics are collected. Since 1930, the Federal Bureau of Investigation has been collecting and publishing an archive of crime statistics. Known as Uniform Crime Reports (UCR), these annual publications contain data from approximately 17,000 law enforcement agencies (FBI 2011). Although the UCR contains comprehensive data on police reports, it fails to take into account the fact that many crimes go unreported due to the victim’s unwillingness to report them, largely based on fear, shame, or distrust of the police. The quality of the data collected by the UCR also varies greatly. Because officers’ approaches to gathering victims’ accounts frequently differed, important details were not always asked for or reported (Cantor and Lynch 2000). To offset this publication, in 1973 the U.S. Bureau of Justice Statistics began to publish a separate report known as the National Crime Victimization Survey (NCVS). The NCVS is a self-report study . A self-report study is a collection of data acquired using voluntary response methods, such as questionnaires or telephone interviews. Each year, survey data are gathered from approximately 135,000 people in the United States on the frequency and type of crime they experience in their daily lives (BJS 2011). The surveys are thorough, providing a wider scope of information than was previously available. This allows researchers to examine crime from more detailed perspectives and to analyze the data based on factors such as the relationship between victims and offenders, the consequences of the crimes, and substance abuse involved in the crimes. Demographics are also analyzed, such as age, race, gender, location, and income level (National Archive of Criminal Justice Data 2010). The NCVS reports a higher rate of crime than the UCR. Though the NCVS is a critical source of statistical information, disadvantages exist. “Non-response,” or a victim’s failure to participate in the survey or a particular question, is among them. Inability to contact important demographics, such as those who don’t have access to phones or frequently relocate, also skews the data. For those who participate, memory issues can be problematic for the data sets. Some victims’ recollection of the crimes can be inaccurate or simply forgotten over time (Cantor and Lynch 2000). While neither of these publications can take into account all of the crimes committed in the country, some general trends may be noted. Crime rates were on the rise after 1960, but following an all-time high in the 1980s and 1990s, rates of violent and non-violent crimes once again started to decline. In 2009, approximately 4.3 million violent crimes occurred in the United States, the majority being assault and robbery. An estimated 15.6 million nonviolent crimes took place, the most common being larceny. Less than half of all violent and nonviolent crimes were reported to the police (BJS 2010). In general, demographic patterns tend to correlate with crime: factors such as sex and socioeconomic status may relate to a person’s chances of being a crime victim or a perpetrator. Women are much more likely than men to be victimized by someone they know, such as a family member or friend, and one-fourth of all nonfatal attacks on women are carried out by a romantic partner (BJS 2011b). The United States Criminal Justice System A criminal justice system is an organization that exists to enforce a legal code. There are three branches of the United States criminal justice system: the police, the courts, and the corrections system. Police Police are a civil force in charge of enforcing laws and public order at a federal, state, or community level. No unified national police force exists in the United States, although there are federal law enforcement officers. Federal officers operate under specific government agencies such as the Federal Bureau of Investigations (FBI); the Bureau of Alcohol, Tobacco, Firearms, and Explosives (ATF); and the Department of Homeland Security (DHS). Federal officers can only deal with matters that are explicitly within the power of the federal government, and their field of expertise is usually narrow. A county police officer may spend time responding to emergency calls, working at the local jail, or patrolling areas as needed, whereas a federal officer would be more likely to investigate suspects in firearms trafficking or provide security for government officials. State police have the authority to enforce statewide laws, including regulating traffic on highways. Local or county police, on the other hand, have a limited jurisdiction with authority only in the town or county in which they serve. Courts Once a crime has been committed and a violator is identified by the police, the case goes to the court. A court is a system that has the authority to make decisions based on law. Similar to the police, the U.S. judicial system is divided into federal courts and state courts. As the name implies, federal courts (including the U.S. Supreme Court) deal with federal matters, including trade disputes, military justice, and government lawsuits. Judges who preside over federal courts are selected by the president with the consent of Congress. State courts vary in their structure, but generally include three levels: trial courts, appellate courts, and state supreme courts. Unlike the large courtroom trials in TV shows, most noncriminal cases are decided by a judge without a jury present. Traffic court and small claims court are both types of trial courts that handle specific civil matters. Criminal cases are heard by trial courts that handle general jurisdictions. Usually, a judge and jury are both present. It is the jury’s responsibility to determine guilt, and the judge’s responsibility to determine the penalty, though in some states, the jury may also decide the penalty. Unless a defendant is found “not guilty,” any member of the prosecution or defense can appeal the case to a higher court. In some states, the case then goes to a special appellate court; in others, it goes to the highest state court, often known as the state supreme court. Corrections The corrections system , more commonly known as the prison system, is tasked with supervising individuals who have been arrested, convicted, and sentenced for a criminal offense. At the end of 2010, approximately seven million Americans were behind bars (BJS 2011d). The United States incarceration rate has grown considerably in the last hundred years. In 2008, more than 1 in 100 U.S. adults were in jail or prison, the highest benchmark in our nation’s history. And while Americans account for 5 percent of the global population, we have 25 percent of the world’s inmates, the largest number of prisoners in the world (Liptak 2008b). Prison is different from jail. A jail provides temporary confinement, usually while an individual awaits trial or parole. Prisons are facilities built for individuals serving sentences of more than a year. Whereas jails are small and local, prisons are large and run by either the state or the federal government. Parole refers to a temporary release from prison or jail that requires supervision and the consent of officials. Parole is different from probation, which is supervised time used as an alternative to prison. Probation and parole can both follow a period of incarceration in prison, especially if the prison sentence is shortened.
principles_of_accounting,_volume_1:_financial_accounting
Summary 7.1 Define and Describe the Components of an Accounting Information System An accounting information system is a set of business processes that record transactions using journals and ledgers (a paper-based system) or computer files (using a computerized system) to keep track of a company’s money and other assets. The key steps in an accounting information system are input, processing, and output. Input: This is any way to record the transaction. Processing: This is a method of combining similar kinds of information (like adding all cash sales together to get a total that is separate from all credit sales; and then adding everything to find total sales). Output: Any way used to display the results of the processing is output. Source document: This is a record that a transaction has taken place; it is often used at the input stage. Storage: This is any method used to save the results generated by the system. Data that is stored is retrieved and used in the input, processing, or output stage. Additional data and information are also stored during these processes. 7.2 Describe and Explain the Purpose of Special Journals and Their Importance to Stakeholders We use special journals to keep track of similar types of transactions. We use special journals to save time because the same types of transactions occur over and over. To decide which special journal to use, first ask, “Is cash involved?” If the answer is “Yes,” then use either the cash receipts or cash disbursements journal. The cash receipts journal always debits cash but can credit almost anything (primarily sales, Accounts Receivable, or a new loan from the bank). The cash disbursements journal always credits cash but can debit almost anything (Accounts Payable, Notes Payable, sales returns and allowances, telephone expense, etc.). The sales journal always debits Accounts Receivable and always credits Sales. If the company uses a perpetual inventory method, it also debits cost of goods sold and credits inventory. The purchases journal always debits Purchases (if using the periodic inventory method) or Inventory (if using the perpetual inventory method) and credits Accounts Payable. We post the monthly balance from each of the special journals to the general ledger at the end of the month. We post from all journals to the subsidiary ledgers daily. We use the general journal for transactions that do not fit anywhere else—generally, for adjusting and closing entries, and can be for sales returns and/or purchase returns. The accounts receivable subsidiary ledger contains all of the details about individual accounts. The total of the accounts receivable subsidiary ledger must equal the total in the Accounts Receivable general ledger account. The accounts payable subsidiary ledger contains all of the details about individual accounts payable accounts. The total of the accounts payable subsidiary ledger must equal the total in the Accounts Payable general ledger account. 7.3 Analyze and Journalize Transactions Using Special Journals Rules of cash receipts journals: Use any time you receive cash. Always debit Cash and credit Accounts Receivable or some other account. Rules of cash disbursements journals: Any time a check is issued, there should be a credit to cash and a debit to AP or typically an expense. Always credit Cash and debit Accounts Payable or some other account. Rules of sales journals: Use only for sales of goods on credit (when customers charge the amount). Always debit Accounts Receivable and credit Sales and debit Cost of Goods Sold and credit Merchandise Inventory when using a perpetual inventory system. Rules of purchases journals: Use only for purchase of goods (inventory) on credit (when you charge the amount). Always debit Merchandise Inventory when using a perpetual inventory system (or Purchases when using a periodic inventory system) and credit Accounts Payable. Post daily to the subsidiary ledgers. Monthly, at the end of each month, after totaling all of the columns in each journal, post to the general ledger accounts which include the Accounts Receivable and Accounts Payable (general ledger) controlling accounts. Note that the only column that you do not post the total to the general ledger account is the Other Accounts column. There is no general ledger account called Other accounts. As mentioned, each entry in that column is posted individually to its respective account. 7.4 Prepare a Subsidiary Ledger A schedule of accounts receivable is a list of all individual accounts and balances that make up accounts receivable. A schedule of accounts payable is a list of all individual accounts and balances that make up accounts payable. 7.5 Describe Career Paths Open to Individuals with a Joint Education in Accounting and Information Systems Data analytics, artificial intelligence systems, data security credentials, blockchain applications, and forensic accounting are some of the areas that provide newer career avenues for accounting professionals. Taxes will continue to be prepared using software that pulls information from the accounting information system. Integrating accounting software with inventory management and electronic payment as used by Walmart and Amazon will set new standards of business process automation. Forensic accounting, data security, artificial intelligence, and data analytics, are all areas for which companies and government agencies will be seeking accounting graduates who are also knowledgeable about information systems.
Chapter Outline 7.1 Define and Describe the Components of an Accounting Information System 7.2 Describe and Explain the Purpose of Special Journals and Their Importance to Stakeholders 7.3 Analyze and Journalize Transactions Using Special Journals 7.4 Prepare a Subsidiary Ledger 7.5 Describe Career Paths Open to Individuals with a Joint Education in Accounting and Information Systems Why It Matters Shane was a talented tennis player at his university. He had a hard time finding a job in his field upon graduation. While he worked toward finding employment, he spent time on a tennis court playing, and parents began asking if he would give lessons to their kids. Excited for the opportunity and income, he started giving lessons and kept track of sessions and payments by printing out notes and piling them on his desk. When it came time to file a tax return, though, he realized that he should have been keeping up with his bookkeeping all along, either manually in some sort of ledger or electronically on his computer. Rather quickly, his student pool grew. Some clients paid up front for lessons, others paid after a few lessons were complete, and still others were not sure if they had paid yet. These various payment methods created a record-keeping challenge for Shane. With winter coming, Shane was exploring the idea of securing court time at an indoor facility to continue teaching and knew he would need to consider court time rental costs in his lesson expenses. Additionally, Shane planned to offer group lessons as well as camps and would need to hire another coach. As Shane’s impromptu business blossomed, it came with additional sources and types of revenues as well as new expenses. He needed a better system to keep track of the financial aspects of his business. A friend told him he needed an accounting information system to organize the financial aspects of his business and to allow him to measure the financial performance of his growing business. But what did Shane’s friend mean? What is an accounting information system? In this chapter, we explain accounting information systems, their evolution from paper-based to digital formats, and how a company—whether small like Shane’s tennis lesson venture or large like a major corporation—uses these systems to stay on top of its finances and to inform important business decisions.
[ { "answer": { "ans_choice": 3, "ans_text": "D" }, "bloom": null, "hl_context": "Firms are also developing and using artificial intelligence ( AI ) systems to perform tasks previously performed by accounting professionals , but now are freeing up the professionals to perform higher-level tasks requiring analysis and judgment . Finally , security of all of this available data is a very important issue , and there are a number of career paths and certifications that information technology professionals can attain . The Information Systems Audit and Control Association ( ISACA ) offers several certifications including Certified Information Systems Auditor ( CISA ) , Certified in Risk and Information System Controls ( CRISC ) , Certified Information Security Manager ( CISM ) , and others . There is so much technology that we are inundated with more information than we can use . <hl> Because the information is being generated by a machine , we generally trust the computation ( although there are cases where a bug in the program can even cause problems with simple math ) , but we also know the old saying , “ garbage in , garbage out . ” The computer does not always know that your typo is garbage . <hl> <hl> If you enter the wrong number , the system processes it as if it were the right number . <hl> That means we have to build some way into the program to control what is input into the system . For example , if you fill out a form online and it asks for your zip code , does it let you enter just four digits ? No — the computer knows that it should only go to the next step if you enter five digits . However , you can enter the wrong digits and it might not catch it . It is critical that we build as many internal controls into our computerized systems as possible so that we can find errors at the input stage before they get into our system . In other words , by using these “ preventive ” controls , we do not allow “ garbage ” data to get into our system .", "hl_sentences": "Because the information is being generated by a machine , we generally trust the computation ( although there are cases where a bug in the program can even cause problems with simple math ) , but we also know the old saying , “ garbage in , garbage out . ” The computer does not always know that your typo is garbage . If you enter the wrong number , the system processes it as if it were the right number .", "question": { "cloze_format": "So far, computer systems cannot yet ________.", "normal_format": "So far, what can computer systems not yet?", "question_choices": [ "receive data and instructions from input devices such as a scanner.", "decide how to record a business transaction.", "communicate with other computers electronically.", "recognize that you made a mistake entering $100 when you meant to enter $101." ], "question_id": "fs-idm458596784", "question_text": "So far, computer systems cannot yet ________." }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 2, "ans_text": "output" }, "bloom": null, "hl_context": "AISs , whether computerized or manual , generally involve three stages : input , processing , and output . <hl> We enter raw data into our system at the input stage and try to correct any errors prior to going on to the next stage of processing the data . <hl> <hl> We ultimately produce “ output , ” which is in the form of useful information . <hl>", "hl_sentences": "We enter raw data into our system at the input stage and try to correct any errors prior to going on to the next stage of processing the data . We ultimately produce “ output , ” which is in the form of useful information .", "question": { "cloze_format": "Any device used to provide the results of processing data is a(n) ________ device.", "normal_format": "What is a(n) device used to provide the results of processing data?", "question_choices": [ "sources", "input", "output", "storage" ], "question_id": "fs-idm209030288", "question_text": "Any device used to provide the results of processing data is a(n) ________ device." }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 2, "ans_text": "C" }, "bloom": null, "hl_context": "<hl> Businesses need a way to input data from the source document such as a sales invoice or purchase order . <hl> <hl> This was previously done with pen and paper and is currently done by keying it in on a computer keyboard ; scanning , with a scanner such as one that reads MICR ( magnetic ink character recognition ) symbols ( found on bank checks ) or POS system scanners at cash registers that scan product bar codes / UPC symbols ; or receiving it by e-transmission ( or electronic funds transfer [ EFT ] ) . <hl> Input often involves the use of hardware such as scanners , keypads , keyboards , touch screens , or fingerprint readers called biometric devices . Once data has been input , it must be processed in order to be useful .", "hl_sentences": "Businesses need a way to input data from the source document such as a sales invoice or purchase order . This was previously done with pen and paper and is currently done by keying it in on a computer keyboard ; scanning , with a scanner such as one that reads MICR ( magnetic ink character recognition ) symbols ( found on bank checks ) or POS system scanners at cash registers that scan product bar codes / UPC symbols ; or receiving it by e-transmission ( or electronic funds transfer [ EFT ] ) .", "question": { "cloze_format": "Source documents ________.", "normal_format": "What are source documents?", "question_choices": [ "are input devices", "are output devices", "do not have to be on paper", "cannot be electronic files" ], "question_id": "fs-idm176579696", "question_text": "Source documents ________." }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 3, "ans_text": "software to process the source data" }, "bloom": null, "hl_context": "<hl> Input : This includes entering the data from the source document on the computer keyboard , electronically scanning the bar code of each product purchased at the grocery store ( at checkout counter and to receive goods from vendor off the truck ) , maybe fingerprinting at the time clock , or keying in a price on the register . <hl> <hl> Businesses need a way to input data from the source document such as a sales invoice or purchase order . <hl> <hl> This was previously done with pen and paper and is currently done by keying it in on a computer keyboard ; scanning , with a scanner such as one that reads MICR ( magnetic ink character recognition ) symbols ( found on bank checks ) or POS system scanners at cash registers that scan product bar codes / UPC symbols ; or receiving it by e-transmission ( or electronic funds transfer [ EFT ] ) . <hl> <hl> Input often involves the use of hardware such as scanners , keypads , keyboards , touch screens , or fingerprint readers called biometric devices . <hl> Once data has been input , it must be processed in order to be useful .", "hl_sentences": "Input : This includes entering the data from the source document on the computer keyboard , electronically scanning the bar code of each product purchased at the grocery store ( at checkout counter and to receive goods from vendor off the truck ) , maybe fingerprinting at the time clock , or keying in a price on the register . Businesses need a way to input data from the source document such as a sales invoice or purchase order . This was previously done with pen and paper and is currently done by keying it in on a computer keyboard ; scanning , with a scanner such as one that reads MICR ( magnetic ink character recognition ) symbols ( found on bank checks ) or POS system scanners at cash registers that scan product bar codes / UPC symbols ; or receiving it by e-transmission ( or electronic funds transfer [ EFT ] ) . Input often involves the use of hardware such as scanners , keypads , keyboards , touch screens , or fingerprint readers called biometric devices .", "question": { "cloze_format": "All of the following can provide source data except ________.", "normal_format": "Which of the following cannot provide source data?", "question_choices": [ "a scanning device at the grocery store", "a utility bill received in the mail", "a bar code reader", "software to process the source data" ], "question_id": "fs-idm465768128", "question_text": "All of the following can provide source data except ________." }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 3, "ans_text": "D" }, "bloom": null, "hl_context": "<hl> Some companies send paper bills in the mail , often asking the recipient to tear off part of the bill and return it with the payment . <hl> <hl> This tear-off portion is a turn-around document and helps ensure that the payment is applied to the correct customer account and invoice . <hl> Generally , this document began as printed output , an invoice , from the billing part of the AIS . When the customer tears off a part of it and returns it in the envelope with a check to the company , it has now been “ turned around ” and will be used as an input source document , called a remittance advice . A remittance advice is a document that customers send along with checks and informs the recipient as to which invoice the customer is paying for . Figure 7.4 is an example of a turn-around document .", "hl_sentences": "Some companies send paper bills in the mail , often asking the recipient to tear off part of the bill and return it with the payment . This tear-off portion is a turn-around document and helps ensure that the payment is applied to the correct customer account and invoice .", "question": { "cloze_format": "A document that asks you to return an identifying part of it with your payment is a(n) ________.", "normal_format": "What document asks you to return an identifying part of it with your payment?", "question_choices": [ "source document", "cloud document", "point-of-sale document", "turn-around document" ], "question_id": "fs-idm196998080", "question_text": "A document that asks you to return an identifying part of it with your payment is a(n) ________." }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 1, "ans_text": "They prevent errors and stop employees from stealing inventory." }, "bloom": null, "hl_context": "<hl> Interestingly , the term accounting information system predates computers . <hl> <hl> Technically , an AIS is a system or set of processes for collecting data about accounting transactions ; recording , organizing , and summarizing the data ; and culminating with the preparation of financial statements and other reports for internal and external users . <hl> These systems or processes can exist as a series of paper ledgers , computer databases , or some combination of the two . Examples of external users include banks that might lend the company money , investors , and the Securities and Exchange Commission ( SEC ) , which requires that publicly traded companies submit audited financial statements . Since business enterprises needed to produce financial statements long before computers existed , they used manual accounting systems to gather the data needed . Data is the term for parts of accounting transactions that constitute the input to an AIS . You have examined many forms of data in this course , for example , the cash received upon the sale of an item is one data point , the reduction of the inventory account related to that specific sold item is another data point , and both the revenue and the cost of goods sold would be additional data points associated with that single transaction of a sale . These data points are summarized and aggregated ( in other words “ processed ” ) into more meaningful and useful numbers that appear in the financial statements , and all this data is typically referred to as financial information . A company that may have used a manual AIS years ago likely uses a computerized AIS today . It is important to remember that a computerized accounting system does not change what we do with accounting transactions , it only changes how we do it , and how we can present the information to different users .", "hl_sentences": "Interestingly , the term accounting information system predates computers . Technically , an AIS is a system or set of processes for collecting data about accounting transactions ; recording , organizing , and summarizing the data ; and culminating with the preparation of financial statements and other reports for internal and external users .", "question": { "cloze_format": "It is false about accounting information systems that ___.", "normal_format": "Which of the following is false about accounting information systems?", "question_choices": [ "They provide reports that people analyze.", "They prevent errors and stop employees from stealing inventory.", "They are designed to gather data about the company’s transactions.", "They consist of processes that involve input of data from source documents, processing, output, and storage." ], "question_id": "fs-idm236075968", "question_text": "Which of the following is false about accounting information systems?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 2, "ans_text": "C" }, "bloom": null, "hl_context": "<hl> All of the amounts owed to the company in the accounts receivable subsidiary ledger must equal the amounts in the accounts receivable general ledger account . <hl>", "hl_sentences": "All of the amounts owed to the company in the accounts receivable subsidiary ledger must equal the amounts in the accounts receivable general ledger account .", "question": { "cloze_format": "The sum of all the accounts in the accounts receivable subsidiary ledger should ________.", "normal_format": "The sum of all the accounts in the accounts receivable subsidiary ledger should what?", "question_choices": [ "equal the accounts receivable account balance in the general ledger before posting any amounts", "equal the accounts payable account balance in the general ledger before posting any amounts", "equal the accounts receivable account balance in the general ledger after posting all amounts", "equal the cash account balance in the general ledger after posting all amounts" ], "question_id": "fs-idm364136464", "question_text": "The sum of all the accounts in the accounts receivable subsidiary ledger should ________." }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 0, "ans_text": "A" }, "bloom": null, "hl_context": "<hl> The use of a reference code in any of the special journals is very important . <hl> <hl> Remember , after a sale is recorded in the sales journal , it is posted to the accounts receivable subsidiary ledger , and the use of a reference code helps link the transactions between the journals and ledgers . <hl> Recall that the accounts receivable subsidiary ledger is a record of each customer ’ s account . It looked like Figure 7.16 for Baker Co .", "hl_sentences": "The use of a reference code in any of the special journals is very important . Remember , after a sale is recorded in the sales journal , it is posted to the accounts receivable subsidiary ledger , and the use of a reference code helps link the transactions between the journals and ledgers .", "question": { "cloze_format": "You just posted a debit to ABC Co. in the accounts receivable subsidiary ledger. The journal from which it came from is the ___ .", "normal_format": "You just posted a debit to ABC Co. in the accounts receivable subsidiary ledger. Which special journal did it come from?", "question_choices": [ "sales journal", "cash receipts journal", "purchases journal", "cash disbursements journal", "general journal" ], "question_id": "fs-idm319013520", "question_text": "You just posted a debit to ABC Co. in the accounts receivable subsidiary ledger. Which special journal did it come from?" }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 0, "ans_text": "sales journal" }, "bloom": null, "hl_context": "In addition to the four special journals , there are two special ledgers , the accounts receivable subsidiary ledger and the accounts payable subsidiary ledger . The accounts receivable subsidiary ledger gives details about each person who owes the company money , as shown in Figure 7.13 . Each colored block represents an individual ’ s account and shows only the amount that person owes the company . <hl> Notice that the subsidiary ledger provides the date of the transaction and a reference column to link the transaction to the same information posted in one of the special journals ( or general journal if special journals are not used ) — this reference is usually a code that references the special journal such as SJ for the sales special journal , as well as the amounts owed in the debit column and the payments made in the credit column . <hl> The amounts owed by all of the individuals , as indicated in the subsidiary ledger , are added together to form the accounts receivable control total , and this should equal the Accounts Receivable balance reported in the general ledger as shown in Figure 7.14 . Key points about the accounts receivable subsidiary ledger are :", "hl_sentences": "Notice that the subsidiary ledger provides the date of the transaction and a reference column to link the transaction to the same information posted in one of the special journals ( or general journal if special journals are not used ) — this reference is usually a code that references the special journal such as SJ for the sales special journal , as well as the amounts owed in the debit column and the payments made in the credit column .", "question": { "cloze_format": "You just posted a credit to Stars Inc. in the accounts receivable subsidiary ledger. The special journal which it came from is the ___ .", "normal_format": "You just posted a credit to Stars Inc. in the accounts receivable subsidiary ledger. Which special journal did it come from?", "question_choices": [ "sales journal", "cash receipts journal", "purchases journal", "cash disbursements journal", "general journal" ], "question_id": "fs-idm362017728", "question_text": "You just posted a credit to Stars Inc. in the accounts receivable subsidiary ledger. Which special journal did it come from?" }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 1, "ans_text": "B" }, "bloom": null, "hl_context": "When the customer pays the amount owed , ( generally using a check ) , bookkeepers use another shortcut to record its receipt . <hl> They use a second special journal , the cash receipts journal . <hl> <hl> The cash receipts journal is used to record all receipts of cash ( recorded by a debit to Cash ) . <hl> In the preceding example , if Baker Co . paid the $ 1,450 owed , there would be a debit to Cash for $ 1,450 and a credit to Accounts Receivable . A notation would be made in the reference column to indicate the payment had been posted to Baker Co . ’ s accounts receivable subsidiary ledger . After Baker Co . ’ s payment , the cash receipts journal would appear as in Figure 7.21 .", "hl_sentences": "They use a second special journal , the cash receipts journal . The cash receipts journal is used to record all receipts of cash ( recorded by a debit to Cash ) .", "question": { "cloze_format": "You just posted a debit to Cash in the general ledger. The special journal which it came from is the ___ .", "normal_format": "You just posted a debit to Cash in the general ledger. Which special journal did it come from?", "question_choices": [ "sales journal", "cash receipts journal", "purchases journal", "cash disbursements journal", "general journal" ], "question_id": "fs-idm631941488", "question_text": "You just posted a debit to Cash in the general ledger. Which special journal did it come from?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 1, "ans_text": "cash receipts journal" }, "bloom": null, "hl_context": "<hl> In the cash receipts journal , the credit can be to Accounts Receivable when a customer pays on an account , or Sales , in the case of a cash sale , or to some other account when cash is received for other reasons . <hl> For example , if we overpaid our electric bill , we could get a refund check in the mail . We would use the cash receipts journal because we are receiving cash , but the credit would be to our Utility Expense account . If you look at the example in Figure 7.23 , you see that there is no column for Utility Expense , so how would it be recorded ? We would use some generic column title such as “ other ” to represent those cash transactions in the subsidiary ledger though the specific accounts would actually be identified by account number in the special journal . We would look up the account number for Utility Expense and credit the account for the amount of the check . If we received a refund from the electric company on January 28 in the amount of $ 100 , we would find the account number for utility expense ( say it is 615 ) and record it . At the end of the month , we total the Cash column in the cash receipts journal and debit the Cash account in the general ledger for the total . In this case there were two entries in the cash receipts journal , the cash received from Baker and the refund check for an overpayment on utilities for a total cash received and recorded in the cash receipts journal of $ 1,550 , as shown in Figure 7.24 .", "hl_sentences": "In the cash receipts journal , the credit can be to Accounts Receivable when a customer pays on an account , or Sales , in the case of a cash sale , or to some other account when cash is received for other reasons .", "question": { "cloze_format": "You just posted a credit to Accounts Receivable. The special journal which it came from is the ___ .", "normal_format": "You just posted a credit to Accounts Receivable. Which special journal did it come from?", "question_choices": [ "sales journal", "cash receipts journal", "purchases journal", "cash disbursements journal", "general journal" ], "question_id": "fs-idm628978928", "question_text": "You just posted a credit to Accounts Receivable. Which special journal did it come from?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 1, "ans_text": "B" }, "bloom": null, "hl_context": "Most companies have four special journals , but there can be more depending on the business needs . The four main special journals are the sales journal , purchases journal , cash disbursements journal , and cash receipts journal . These special journals were designed because some journal entries occur repeatedly . <hl> For example , selling goods for cash is always a debit to Cash and a credit to Sales recorded in the cash receipts journal . <hl> Likewise , we would record a sale of goods on credit in the sales journal , as a debit to accounts receivable and a credit to sales . Companies using a perpetual inventory system also record a second entry for a sale with a debit to cost of goods sold and a credit to inventory . You can see sample entries in Figure 7.9 .", "hl_sentences": "For example , selling goods for cash is always a debit to Cash and a credit to Sales recorded in the cash receipts journal .", "question": { "cloze_format": "You just posted a credit to Sales and a debit to Cash. The special journal from which it came from is the ___ .", "normal_format": "You just posted a credit to Sales and a debit to Cash. Which special journal did it come from?", "question_choices": [ "sales journal", "cash receipts journal", "purchases journal", "cash disbursements journal", "general journal" ], "question_id": "fs-idm631601440", "question_text": "You just posted a credit to Sales and a debit to Cash. Which special journal did it come from?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 2, "ans_text": "is a large, company-wide integrated accounting information system that connects all of a company’s applications" }, "bloom": null, "hl_context": "Later in the section on how to Prepare a Subsidiary Ledger , you will be provided with a series of transactions for a small business and you will be asked to first enter the transactions manually into the appropriate journal , post the information from the journals to the general ledger , prepare trial balances , adjusting and closing entries , and manually produce financial statements just as Macy ’ s or any other business would have done prior to the use of various computer technologies . You will then perform the same tasks using QuickBooks , a popular accounting software program used by many small and medium-sized businesses . A company as large as Macy ’ s has stores in locations all over the country and a large volume of transactions , so it is more likely to use a software package designed to meet the needs of a very large business . <hl> This is often referred to as an enterprise resource planning ( ERP ) system which stands for enterprise resource planning ( ERP ) system . <hl> <hl> An ERP system integrates all of the company ’ s computerized systems including accounting systems and nonaccounting systems . <hl> That is , large companies have various accounting subsystems such as the revenue system ( sales / accounts receivable / cash receipts ) , the expenditure system ( purchasing / accounts payable / cash disbursements ) , the production system , the payroll system , and the general ledger system . Nonaccounting systems might include research and development , marketing , and human resources , which , while not an integral part of the accounting system , in a large companywide ERP system are integrated with the accounting modules . Examples of popular ERP software systems are PeopleSoft and SAP .", "hl_sentences": "This is often referred to as an enterprise resource planning ( ERP ) system which stands for enterprise resource planning ( ERP ) system . An ERP system integrates all of the company ’ s computerized systems including accounting systems and nonaccounting systems .", "question": { "cloze_format": "An enterprise resource planning (ERP) system ________.", "normal_format": "What is an enterprise resource planning (ERP) system?", "question_choices": [ "is software to help you prepare your tax return", "requires that you pay ransom before you can operate it", "is a large, company-wide integrated accounting information system that connects all of a company’s applications", "is part of the darknet" ], "question_id": "fs-idm757178432", "question_text": "An enterprise resource planning (ERP) system ________." }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 0, "ans_text": "to find business trends" }, "bloom": null, "hl_context": "We use accounting information to make decisions about the business . Computer applications now provide so much data that data analytics is one of the newest career areas in business . Universities are beginning to offer degrees in data analysis . Software companies have created different applications to analyze data including SAS , Apache Hadoop , Apache Spark , SPSS , RapidMiner , Power BI , ACL , IDEA , and many more to help companies discover useful information from the transactions that occur . <hl> Big data refers to the availability of large amounts of data from various sources , including the internet . <hl> <hl> For example , social media sites contain tremendous amounts of data that marketing companies analyze to determine how popular a product is , and how best to market it . <hl> <hl> There is so much data to analyze that new ways of mining it for predictive value have evolved . <hl>", "hl_sentences": "Big data refers to the availability of large amounts of data from various sources , including the internet . For example , social media sites contain tremendous amounts of data that marketing companies analyze to determine how popular a product is , and how best to market it . There is so much data to analyze that new ways of mining it for predictive value have evolved .", "question": { "cloze_format": "Big data is mined ________.", "normal_format": "Why is big data mined?", "question_choices": [ "to find business trends", "to record transactions", "as an alternative to creating an accounting information system", "as an alternative to the darknet" ], "question_id": "fs-idm204034528", "question_text": "Big data is mined ________." }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 1, "ans_text": "B" }, "bloom": null, "hl_context": "<hl> Firms are also developing and using artificial intelligence ( AI ) systems to perform tasks previously performed by accounting professionals , but now are freeing up the professionals to perform higher-level tasks requiring analysis and judgment . <hl> Finally , security of all of this available data is a very important issue , and there are a number of career paths and certifications that information technology professionals can attain . The Information Systems Audit and Control Association ( ISACA ) offers several certifications including Certified Information Systems Auditor ( CISA ) , Certified in Risk and Information System Controls ( CRISC ) , Certified Information Security Manager ( CISM ) , and others . There is so much technology that we are inundated with more information than we can use . Because the information is being generated by a machine , we generally trust the computation ( although there are cases where a bug in the program can even cause problems with simple math ) , but we also know the old saying , “ garbage in , garbage out . ” The computer does not always know that your typo is garbage . If you enter the wrong number , the system processes it as if it were the right number . That means we have to build some way into the program to control what is input into the system . For example , if you fill out a form online and it asks for your zip code , does it let you enter just four digits ? No — the computer knows that it should only go to the next step if you enter five digits . However , you can enter the wrong digits and it might not catch it . It is critical that we build as many internal controls into our computerized systems as possible so that we can find errors at the input stage before they get into our system . In other words , by using these “ preventive ” controls , we do not allow “ garbage ” data to get into our system .", "hl_sentences": "Firms are also developing and using artificial intelligence ( AI ) systems to perform tasks previously performed by accounting professionals , but now are freeing up the professionals to perform higher-level tasks requiring analysis and judgment .", "question": { "cloze_format": "Artificial intelligence refers to ________.", "normal_format": "What does artificial intelligence refer to?", "question_choices": [ "tutorials that can make humans smarter than they naturally are", "programming computers to mimic human reasoning and perform tasks previously performed by humans", "humans that do not possess reasonably high IQs", "a concept that exists only in science fiction but has not yet been achieved today" ], "question_id": "fs-idm215563008", "question_text": "Artificial intelligence refers to ________." }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 3, "ans_text": "involves the use of a single shared ledger between the many parties that may be involved in a transaction." }, "bloom": null, "hl_context": "Another emerging area involves cryptocurrency , or the use of a digital currency that uses encryption technologies that make these cryptocurrencies impossible to counterfeit . The use of cryptocurrency does not require a bank to transfer or clear funds as is the case with other currencies . Bitcoin is the most well-known cryptocurrency . Blockchain is the platform on which Bitcoin is built . <hl> Blockchain serves as a shared ledger for Bitcoin but is also the foundation of many other applications . <hl> <hl> Simply put , blockchain offers different parties to a transaction ( e . g . , a buyer and a seller ) the opportunity to use a shared ledger rather than each having their own separate ledgers as is the case with traditional systems . <hl> Bitcoin is currently accepted by some large , well-known companies including PwC and EY ( the two largest of the “ big 4 ” accounting firms ) , and Overstock.com .", "hl_sentences": "Blockchain serves as a shared ledger for Bitcoin but is also the foundation of many other applications . Simply put , blockchain offers different parties to a transaction ( e . g . , a buyer and a seller ) the opportunity to use a shared ledger rather than each having their own separate ledgers as is the case with traditional systems .", "question": { "cloze_format": "Blockchain is a technology that ________.", "normal_format": "Which of the following is correct about blockchain?", "question_choices": [ "is in the early stages of being developed", "was a failed attempt to change the way we do business", "refers to an application developed strictly for the real estate business", "involves the use of a single shared ledger between the many parties that may be involved in a transaction." ], "question_id": "fs-idm216256096", "question_text": "Blockchain is a technology that ________." }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 3, "ans_text": "D" }, "bloom": null, "hl_context": "Another emerging area involves cryptocurrency , or the use of a digital currency that uses encryption technologies that make these cryptocurrencies impossible to counterfeit . <hl> The use of cryptocurrency does not require a bank to transfer or clear funds as is the case with other currencies . <hl> <hl> Bitcoin is the most well-known cryptocurrency . <hl> Blockchain is the platform on which Bitcoin is built . Blockchain serves as a shared ledger for Bitcoin but is also the foundation of many other applications . Simply put , blockchain offers different parties to a transaction ( e . g . , a buyer and a seller ) the opportunity to use a shared ledger rather than each having their own separate ledgers as is the case with traditional systems . <hl> Bitcoin is currently accepted by some large , well-known companies including PwC and EY ( the two largest of the “ big 4 ” accounting firms ) , and Overstock.com . <hl>", "hl_sentences": "The use of cryptocurrency does not require a bank to transfer or clear funds as is the case with other currencies . Bitcoin is the most well-known cryptocurrency . Bitcoin is currently accepted by some large , well-known companies including PwC and EY ( the two largest of the “ big 4 ” accounting firms ) , and Overstock.com .", "question": { "cloze_format": "It is not true about cybercurrency that ___.", "normal_format": "Which of the following is not true about cybercurrency?", "question_choices": [ "Bitcoin is one of several cybercurrencies.", "It is an alternate currency that does not go through the banking system.", "It does not involve the actual exchange of physical currency.", "It is not accepted by any legitimate businesses." ], "question_id": "fs-idm203836800", "question_text": "Which of the following is not true about cybercurrency?" }, "references_are_paraphrase": null } ]
7
7.1 Define and Describe the Components of an Accounting Information System Today, when we refer to an accounting information system (AIS) , we usually mean a computerized accounting system, because computers and computer software that help us process accounting transactions have become relatively inexpensive. The benefits of using a computerized accounting system outweigh the costs of purchasing one, and almost all companies, even very small ones, can afford to and do use a computerized accounting system. That is not to say that paper-based or manual accounting systems and processes have disappeared. Most businesses have some form of both noncomputerized and computerized systems. QuickBooks is an example of a relatively inexpensive accounting software application that is popular with small and medium-sized businesses. Manual and Computerized Accounting Information Systems Interestingly, the term accounting information system predates computers. Technically, an AIS is a system or set of processes for collecting data about accounting transactions; recording, organizing, and summarizing the data; and culminating with the preparation of financial statements and other reports for internal and external users. These systems or processes can exist as a series of paper ledgers, computer databases, or some combination of the two. Examples of external users include banks that might lend the company money, investors, and the Securities and Exchange Commission (SEC), which requires that publicly traded companies submit audited financial statements. Since business enterprises needed to produce financial statements long before computers existed, they used manual accounting systems to gather the data needed. Data is the term for parts of accounting transactions that constitute the input to an AIS. You have examined many forms of data in this course, for example, the cash received upon the sale of an item is one data point, the reduction of the inventory account related to that specific sold item is another data point, and both the revenue and the cost of goods sold would be additional data points associated with that single transaction of a sale. These data points are summarized and aggregated (in other words “processed”) into more meaningful and useful numbers that appear in the financial statements, and all this data is typically referred to as financial information. A company that may have used a manual AIS years ago likely uses a computerized AIS today. It is important to remember that a computerized accounting system does not change what we do with accounting transactions, it only changes how we do it, and how we can present the information to different users. Let’s consider the example of a company that came into existence before we had computers, the department store Macy’s , which currently operates stores in nearly all fifty US states. Macy’s began as a small, fancy dry goods store that opened in New York City in 1858, became a department store, R.H. Macy & Co., in 1877 using the same red star logo it still uses today. We can assume that even one hundred years ago, Macy’s needed to perform the same tasks it does today: purchase merchandise inventory to sell to customers; record returns of some of the inventory; record sales made to customers at the sales price; record the cost of the goods sold at the amount Macy’s paid to purchase them; record payments from customers; record returns from customers; purchase other kinds of items needed for operations, like office supplies and fixed assets; pay for prior purchases; pay for rent, utilities, and other services; pay employees; enter all of these transactions; post all transactions; record adjusting journal entries; record closing journal entries; keep track of its receivables, payables, and inventory; and produce financial statements for internal and external users as well as other reports useful to managers in assessing various performance measures needed to evaluate the success of the company. As you might imagine, doing all this without computers is quite different than performing these tasks with the aid of computers. In a manual system, each business transaction is recorded, in the form of a journal entry in the general journal or one of the four common other special journals described in Describe and Explain the Purpose of Special Journals and Their Importance to Stakeholders , using pen and paper. Journal entries are then posted to a general ledger; balances would be computed by hand or with an adding machine/calculator for each general ledger account; a trial balance is prepared; adjusting journal entries are prepared; and finally financial statements prepared, all manually. Concepts In Practice Modernization of Accounting Systems In 1955, in one of the earliest uses of a true computer to facilitate accounting tasks, General Electric Company used a UNIVAC computer to process its payroll. Initially it took the computer forty hours just to process payroll for one pay period. The first modern era spreadsheet software for personal computers, VisiCalc, became available in 1978. Thus, between these time periods there were minor improvements to the use of computerized accounting tools, but it was not until the mid-1980s that comprehensive computerized accounting programs became widely used. Thus, prior to the mid-1980s, much accounting was done manually or using a variety of less-advanced computer systems in conjunction with manual systems. Imagine the number of bookkeepers it would take to record the transactions of many companies. For example, on the first day of business at Macy’s in 1858, the store had revenues of $11.06. 1 The actual accounting ledger used to record those sales is shown in Figure 7.2 , which seems quite simple. Today Macy’s has over $24 billion in sales revenue—can you imagine accounting for all of those transactions (along with all expenses) by hand? 1 Fraser Sherman. “The History of Computerized Accounting.” Career Trend. January 14, 2019. https://careertrend.com/about-6328213-history-computerized-accounting.html Today, Macy’s and other large and small companies perform the same accounting tasks using computer hardware (computers, printers, and keyboards), and software. For example, cashiers can enter transactions into a computer using a keyboard, scanner, or touch screen. The screen displays the data entered or fields available for data entry. As an example, most retail stores have a point-of-sale system (POS) that enters the sale by scanning the item at the point of sale , meaning at the time the transaction is made. This system records the sale and at the same time updates inventory by reducing it based on the number of items purchased. Later in the section on how to Prepare a Subsidiary Ledger , you will be provided with a series of transactions for a small business and you will be asked to first enter the transactions manually into the appropriate journal, post the information from the journals to the general ledger, prepare trial balances, adjusting and closing entries, and manually produce financial statements just as Macy’s or any other business would have done prior to the use of various computer technologies. You will then perform the same tasks using QuickBooks, a popular accounting software program used by many small and medium-sized businesses. A company as large as Macy’s has stores in locations all over the country and a large volume of transactions, so it is more likely to use a software package designed to meet the needs of a very large business. This is often referred to as an enterprise resource planning (ERP) system which stands for enterprise resource planning (ERP) system. An ERP system integrates all of the company’s computerized systems including accounting systems and nonaccounting systems. That is, large companies have various accounting subsystems such as the revenue system (sales/accounts receivable/cash receipts), the expenditure system (purchasing/accounts payable/cash disbursements), the production system, the payroll system, and the general ledger system. Nonaccounting systems might include research and development, marketing, and human resources, which, while not an integral part of the accounting system, in a large companywide ERP system are integrated with the accounting modules. Examples of popular ERP software systems are PeopleSoft and SAP. Like many businesses today, Macy’s also maintains a company website and engages in e-commerce by offering the sale of many company products online. Accounting software companies like QuickBooks and larger software vendors have upgraded the ways in which they can provide AIS software to meet these needs. For example, a small local retail shoe store can purchase QuickBooks software provided on an electronic storage device such as a CD and upload it to be stored on the hard drive of the company’s computers, or the store can purchase a “cloud” version. The cloud version provides the shoe store purchasing the software with access to the QuickBooks software online via a user ID and password with no need to load the software on the store’s computers. QuickBooks updates the software when new versions are released and stores the company’s accounting data in the cloud. Cloud computing refers to using the internet to access software and information storage facilities provided by companies rather than, or in addition to, storing this data on the company’s computer hard drive or in paper form. An advantage of cloud computing is that company employees can access the software and enter transactions from any device with an internet connection at any location. The company pays a monthly fee for access to updated software, which can be less costly than buying software stored on individual computers. Potential disadvantages include security concerns because an outside company is storing company programs and data, and if the hosting company experiences technical difficulties, companies paying for these services may temporarily be unable to access their own data or conduct business. Nevertheless, cloud services are increasingly popular. Here, we illustrate the concepts and practices of an AIS using Intuit QuickBooks, a popular and widely used AIS. While a company typically selects an AIS to suit its specific needs, all systems should have components capable of: inputting/entering data (e.g., entering a sale to a customer); storing data; processing data and computing additional amounts related to transactions (e.g., computing sales tax on the sale, as well as shipping costs and insurance fees; computing an employee’s pay by multiplying hours worked by hourly pay rate; processing inventory changes from both inventory purchases and inventory sales and data from any other transaction that occurs in the business); aggregating/summarizing data (e.g., computing total sales for the year); presenting data (e.g., producing a balance sheet and other financial statements and reports for the year); and storing data (such as the customer’s name, address, shipping address, and credit limit). AISs, whether computerized or manual, generally involve three stages: input, processing, and output. We enter raw data into our system at the input stage and try to correct any errors prior to going on to the next stage of processing the data. We ultimately produce “output,” which is in the form of useful information. Inputting/Entering Data A source document is the original document that provides evidence that a transaction occurred. If you hire a company to paint your house, it will most likely provide a document showing how much you owe. That is the company’s sales document and your invoice. When you pay, your check or digital transaction record is also a source document for the company that provided the service, in this case, the home painter. Assume you go into the university bookstore to purchase a school sweatshirt, and it is sold out. You then fill out a document ordering a size medium sweatshirt in blue. The form you fill out is a purchase order to you, and it is a sales order to the university bookstore. It is also a source document that provides evidence that you have ordered the sweatshirt. Assume the bookstore does not ask you to pay in advance because it is not sure it will be able to obtain the sweatshirt for you. At that point, no sale has been made, and you owe no money to the bookstore. A few days later, the bookstore manages to acquire the sweatshirt you ordered and sends you an email notifying you of this. When you return to the bookstore, you are presented with the sweatshirt and an invoice (also known as a bill) that you must pay in order to take your sweatshirt home. This invoice/bill is also a source document. It provides evidence of the sale and your obligation to pay that amount. Let’s look at an example. Figure 7.3 is a source document—an invoice (bill) from Symmetry Mold Design for mold design services. Note the terms (agreements about payments) are listed at the top and how the company calculates those outcomes at the bottom. Some companies send paper bills in the mail, often asking the recipient to tear off part of the bill and return it with the payment. This tear-off portion is a turn-around document and helps ensure that the payment is applied to the correct customer account and invoice. Generally, this document began as printed output, an invoice, from the billing part of the AIS. When the customer tears off a part of it and returns it in the envelope with a check to the company, it has now been “turned around” and will be used as an input source document, called a remittance advice. A remittance advice is a document that customers send along with checks and informs the recipient as to which invoice the customer is paying for. Figure 7.4 is an example of a turn-around document. Both manual and computerized accounting systems utilized source documents. E-commerce systems have some additional source documents related to online transactions. Source documents help to establish an audit trail , which is a trail of evidence documenting the history of a specific transaction starting from its inception/source document and showing all the steps it went through until its final disposition. The trail of source documents and other records (the audit trail) makes it easier to investigate errors or questions by customers, vendors, employees, and others. For example, when a customer places an order by phone, by mail, or online, the sales order becomes the source document. If the customer does not receive the product ordered, the company can locate the original order, see if a picking ticket was generated (a picking ticket tells warehouse employees what inventory items the customer ordered, that now need to be picked off the shelf), locate the shipping documents, which provide evidence that the product was given to the shipper, and check for customer signature confirming receipt of goods. The trail of documents and entries in journals and ledgers and their electronic equivalent generated by this transaction provides evidence of all the steps that took place along the way. This makes it easy for anyone to verify or investigate, and perhaps find the weak links, where the process may have broken down. It allows the company to identify the reason why the customer never received the goods ordered. Maybe the order was never shipped because the company was out of stock of this specific product, maybe it was shipped and left at the customer’s doorstep with no signature requested, or maybe the order was shipped to the wrong customer or to an incorrect address. An audit trail will help company personnel investigate any of these common issues. It should also help them identify weaknesses in their processes and precipitate improvements. Businesses need a way to input data from the source document such as a sales invoice or purchase order. This was previously done with pen and paper and is currently done by keying it in on a computer keyboard; scanning, with a scanner such as one that reads MICR (magnetic ink character recognition) symbols (found on bank checks) or POS system scanners at cash registers that scan product bar codes/UPC symbols; or receiving it by e-transmission (or electronic funds transfer [EFT]). Input often involves the use of hardware such as scanners, keypads, keyboards, touch screens, or fingerprint readers called biometric devices. Once data has been input, it must be processed in order to be useful. Processing Data Companies need the accounting system to process the data that has been entered and transform it into useful information. In manual accounting systems, employees process all transaction data by journalizing, posting, and creating financial reports using paper. However, as technology has advanced, it became easier to keep records by using computers with software programs specifically developed for accounting transactions. Computers are good at repetition and calculations, both of which are involved in accounting, and computers can perform these calculations and analyses more quickly, and with fewer errors, thus making them a very effective tool for accounting from both an input and an output standpoint. Link to Learning See a list of popular bookkeeping software packages. With this information, potential options for sample accounting software options can be evaluated. Output: Presenting Information An AIS should provide a way to present system output (printed page, screen image, e-transmission). Any accounting software application such as that used by large companies (an ERP system) or one used by smaller businesses (QuickBooks) can easily print financial statements and other documents as well as display them on the screen. Some financial information must be provided to other sources such as banks or government agencies, and though in past decades everything was presented and submitted on paper, today, most of this information is submitted electronically, and AISs help facilitate having the information in the necessary electronic format. Many banks require electronic data, and the Internal Revenue System (IRS) accepts your information as a digital transmission instead of a paper form. In 2017, 92 percent of all taxpayers who filed their own taxes did so electronically. 2 Most corporations choose to file their taxes electronically, and those with assets over $10 million are required to file electronically with the IRS. 3 Since May 5, 1996, all publicly traded companies are required to submit their filings, such as financial statements and stock offerings, to the SEC electronically. 4 The SEC places all the data into an electronic database known as the Electronic Data Gathering, Analysis, and Retrieval System (EDGAR) . This database allows anyone to search the database for financial and other information about any publicly traded company. Thus, AISs facilitate not only internal access to financial information, but the sharing of that information externally as needed or required. Just as the EDGAR system used by the SEC stores data for retrieval, an AIS must provide a way to store and retrieve data. 2 Income Tax Return Statistics. eFile. May 2018. https://www.efile.com/efile-tax-return-direct-deposit-statistics/ 3 Income Tax Return Statistics. eFile. May 2018. https://www.efile.com/efile-tax-return-direct-deposit-statistics/ 4 There is a hardship exemption for companies that cannot file their documents electronically. See U.S. Securities and Exchange Commission. Important Information about EDGAR. February 16, 2010. https://www.sec.gov/edgar/aboutedgar.htm Storing Data Data can be stored by an AIS in paper, digital, or cloud formats. Before computers were widely used, financial data was stored on paper, like the journal and ledger shown in Figure 7.5 . As technology has evolved, so have storage systems—from floppy disks to CDs, thumb drives, and the cloud. The hard drive on your computer is a data storage device, as is an external hard drive you can purchase. Data that is stored must have the ability to be retrieved when needed. As you can see from Figure 7.6 , stored data comes from and/or flows through the three main functions of an AIS (input, processes, and output) with the end result being the use of the data in forms needed for decision-making, such as financial statements. Access to the ability to input data, manage processes, or retrieve data requires adequate controls to prevent fraud or unauthorized access and requires the implementation of data security measures. Figure 7.6 illustrates the key functions performed by an AIS. Your Turn The Steps in an Accounting Information System The three steps of an accounting information system are input, processing, and output. Data is the raw ingredient used in these processes. Some of the data may be obtained from a source document, and other data is obtained from the database where it had previously been stored. When the data has been processed, the final result is usually information. Information is more useful than data. Take, for example, another process that a bakery might use to bake chocolate chip cookies. While computers might not necessarily need to be involved, we begin the process by assembling a bunch of raw ingredients such as eggs, sugar, flour, chocolate chips, and oil, in a large bowl. Taking a spoonful of what is in the bowl at the time is not very pleasing to the taste buds or “useful” to someone craving a chocolate chip cookie. We process the raw ingredients by mixing them well and turning them into dough, cutting them into shapes, baking them, and glazing them. Similarly, raw data about a single sale contained on the sales invoice, such as customer name, date of sale, and amount of sale, is individually not very useful to a financial statement user such as an investor. However, by processing the data related to the sale, making sure it is correct by checking that the number of items ordered were in stock and actually shipped, aggregating it with other sales for the period, and producing an income statement containing the sales for the period is substantially more useful than the individual pieces of data relating to a single sale. Can you give an example of each of the three steps, as well as a source document that might be used in the input stage and stored data that might be used in the input and processing stages, first for a grocery store, and then a medical office? Solution Grocery store: Source Document: This would include a check to be deposited; totals from each cash register, including total cash; an invoice for produce; an application for employment by a potential new employee; time card information; a W-4 form (employment information); and so on. Input: This includes entering the data from the source document on the computer keyboard, electronically scanning the bar code of each product purchased at the grocery store (at checkout counter and to receive goods from vendor off the truck), maybe fingerprinting at the time clock, or keying in a price on the register. Processing: A cash register processes (accumulates and totals) different categories of items (coupons, checks, and charges) by the user; inventory can be tracked by RFID (radio-frequency identification); and software programs can process information gathered by individual cash registers as well as employee information. Output: Data that has been processed can be viewed on a computer screen, printed as a hard copy (paper output), or sent as electronic output from the cash register to the computer (can be done wirelessly or with a cable). Storage: Data can be stored in the company database on its computer hard drive or as cloud storage. Hopefully the store is also paying for safe backup storage offsite (in case of fire at the store or hackers attempting to obtain information), generally accessed through the internet and stored in “the cloud.” Otherwise, storage can be on paper printouts, the computer hard drive, disks, or external drives. The data that is stored may be retrieved and used at the input, processing, and output stages. Doctor’s office: Source Document: This includes a check to be deposited from the patient; the patient’s insurance information on file; a doctor’s record of the diagnosis and procedures performed on the patient, to be submitted to the insurance company; and an invoice for medical supplies. Input: Data from the source document, for example, containing the diagnosis and a treatment plan, would be entered on the computer keyboard. Processing: The system might retrieve the treatment codes corresponding to every procedure the doctor performed, so it contains the appropriate information for the insurance company. Output: The treatment form is printed and then mailed to the insurance company for payment. Storage: The diagnosis and treatment plan are stored on the computer database for retrieval on the next visit for this patient. The form to be sent to the insurance company is also stored electronically so there can be follow-up until the payment from the insurance company is received. Also note that during processing, the system had to retrieve the treatment codes from a file of all of the codes that was stored in the database. Your Turn The Accounting Information System (AIS) What are some of the types of information the accounting information system should be able to provide to the owners, managers, and employees of business, at the end of the day, or week, or month, which they in turn may need to provide to other external users? Solution Information for internal purposes will include total sales and how much it cost to generate the sales. Also considered is how much inventory is on hand so a decision can be made as to whether or not to order more inventory. The company will need to record all of the economic events of the business in order to find total sales, cost of goods sold, expenses, and net income, as well as the number of hours employees worked, the employee’s social security number, and how much the company promised to pay the employee per hour. Information for external users, such as the IRS or state and local government agencies, would include income tax returns and sales and payroll tax forms. The business owners and managers will need all sales and expenses, sales tax collected, and employees’ earnings. In other words, the company needs an AIS. While an AIS has the primary functions of input, processing, output, and storage, each company or system will decide on the exact steps and processes under each of these broad functions. We know that data is used to create the types of information needed by users to make decisions. One way in which a retail organization may obtain, input, process, and store data related to a sales transaction is through a point-of-sale system (POS) . When a customer is ready to buy an item, the cashier scans the product being purchased, the price is retrieved from the price file, the sale is recorded, and inventory is updated. Most POS systems include a scanner, a computer screen, or a tablet with a touch screen. Customer payments are stored in the cash drawer. For noncash sales, credit card readers allow customers to insert, swipe, or tap their cards to pay (which also helps prevent keyboard input errors and keeps the information safer). Ethical Considerations Ethical Standards in Retail Stores Professional sales employees operate the POS systems. There is an ethical code for sales professionals created by the Association of Professional Sales to help sales professionals maintain good judgment. 5 The organization sets forth standards such as the following: 5 Association of Professional Sales. “APS Sales Code of Conduct.” n.d. https://www.associationofprofessionalsales.com/professional-development/sales-code-conduct-aps-ethical-professional/aps-sales-code-conduct/ Maintain the highest standards of integrity in all business relationships. Provide our customers with a buying experience in which we “do the right thing and thereby help get the right results.” Promote and protect good sales practices. Always act in line with my organization’s codes and within the law. Accountants can assist sales professionals in creating an ethical environment. The ethical environment will permit the users of accounting data to make solid business decisions and to better operate a company. However, the POS is just part of the AIS. As each sale is entered into the register, other data is collected, recorded, and processed by the AIS and becomes information. Data about each sale is recorded in the information system: what was sold, how much it cost, the sales price, and any sales tax. It also records the time of day, the clerk, and anything else the company programmed the cash register to record. When all the sales for the day are totaled, it provides information in the form of organized and processed data with meaning to the company. A business might want to see which hour of the day resulted in the most sales, or to know which product was the best seller. An AIS can provide this information. A system is created when processes work together to generate information for the business. The sales process accesses customers, accounts receivable, and inventory data and updates the appropriate files. The purchases process also accesses inventory and accounts payable and updates them, because most companies buy goods on credit. Since no two companies operate exactly the same way, you would expect each company to have a slightly different AIS. Some businesses do not have a cash register, but they will still have a Sales account. Some companies only have cash sales, so they would not have an Accounts Receivable account. Regardless of the type of business—retail, manufacturing, or service—an AIS is an important component of the business as it is this system that provides the information needed by internal and external decision-makers. Concepts In Practice Is This an Accounting Information System? Do you think your average food truck proprietor has an accounting information system? Food trucks will have some type of accounting information system whether paper based or electronic. One common method of creating an accounting information system in this type of business environment is to use an app, such as Square Point of Sale ( Square Inc. ). The Square Point of Sale (POS) software system keeps track of the sales. With this type of system, a food truck will likely have a Square Stand (a tablet-based POS), a cash drawer, and printers. The information input into the Square Stand is stored on Square servers using the cloud (online storage space offered by different companies and products) and is accessible by the company via an online dashboard. This system allows the handling of both cash sales and credit card sales. These components—the Square Point of Sale software, the Square Stand, cash drawer, and the printers—make up part of the accounting information system for a food truck. IFRS Connection Accounting Information Systems in an International Business Environment All companies, regardless of whether they are domestic or international, will have an accounting information system with the features described in this chapter. It would be easy to assume that the accounting information systems created by public companies in the United States are created based on US generally accepted accounting principles (GAAP). This implies that these companies design their processes and controls so that in addition to meeting the reporting and monitoring goals of the company, the system also collects, measures, and reports the information that is required under US GAAP. But is this true? What about companies that have subsidiaries or a portion of their operations in another country? Do purely international companies use accounting information systems similar to their US counterparts? As previously indicated, all companies will create some sort of accounting information system. General Electric (GE) , as a US-based manufacturer, uses an accounting information system that allows it to record, collect, produce, and analyze the operations of its various businesses. Since GE is a US corporation, headquartered in Boston, Massachusetts, its accounting information system is designed around the rules set out by US GAAP. Fiat Chrysler Automobiles (FCA) is headquartered in the United Kingdom, and it designs its accounting information system to produce financials under International Financial Reporting Standards (IFRS). On the surface, it looks as though each company will create an information system based on the accounting rules in its own home country. However, it is not quite that simple. Today, companies take advantage of the ability to borrow money across borders. The lenders often require the financial statements of the borrower to be presented using the accounting rules required by the lender’s country. For example, if GE wanted to borrow money from the Royal Bank of Scotland , it would likely have to present its financial statements based on IFRS rules. Similarly, if FCA wanted to borrow from Citibank , it would need its financial statements in US GAAP form. Borrowing is not the only reason a company may need to present financial statements based on a different set of accounting principles. As of 2017, GE had over 130 subsidiaries, and these businesses were located across 130 countries. A subsidiary is a business over which the parent company has decision-making control, usually indicated by an ownership interest of more than 50 percent. Many of these GE subsidiaries established their accounting information systems based on the accepted accounting principles in the countries in which they were located, as required in order to be in compliance with local regulations such as for local taxes. Thus, GE must convert the financial information obtained from the subsidiary’s accounting information system, often based on IFRS, to US GAAP in order to consolidate the transactions and operations of all of the subsidiaries with those of the parent company to create one set of financial statements. We have basically become a two GAAP world—IFRS and US GAAP—and many companies will find it necessary to have accounting information systems that can handle both sets of rules due to the global nature of business and the global nature of raising money through borrowing and issuing stock. This may seem crazy, to have two systems, but a little over ten years ago there were more than seventy different GAAP. Today, since many countries now use IFRS, the quality and consistency of financial reporting have improved. As a result, the cost associated with having accounting information systems that can combine many different sets of accounting rules has decreased. 7.2 Describe and Explain the Purpose of Special Journals and Their Importance to Stakeholders The larger the business, the greater the likelihood that that business will have a large volume of transactions that need to be recorded in and processed by the company’s accounting information system. You’ve learned that each transaction is recorded in the general journal, which is a chronological listing of transactions. In other words, transactions are recorded into the general journal as they occur. While this is correct accounting methodology, it also can create a cumbersome general journal with which to work and may make finding specific pieces of information very challenging. For example, assume customer John Smith charged an item for $100 on June 1. In the general journal, the company would record the following. This journal entry would be followed by a journal entry for every other transaction the company had for the remainder of the period. Suppose, on June 27, Mr. Smith asked, “How much do I owe?” To answer this question, the company would need to review all of the pages of the general journal for nearly an entire month to find all of the sales transactions relating to Mr. Smith. And if Mr. Smith said, “I thought I paid part of that two weeks ago,” the company would have to go through the general journal to find all payment entries for Mr. Smith. Imagine if there were 1,000 similar credit sales transactions for the month, each one would be written in the general journal in a similar fashion, and all other transactions, such as the paying of bills, or the buying of inventory, would also be recorded, in chronological order, in the general journal. Thus, recording all transactions to the general journal makes it difficult to find the particular tidbits of information that are needed for one of our customers, Mr. Smith. The use of special journal and subsidiary ledgers can make the accounting information system more effective and allow for certain types of information to be obtained more easily. Your Turn Using General Ledger (Control) Accounts Here is the information from the accounts payable subsidiary ledger: What should the total be in the Accounts Payable Control Total? Here is the information from the accounts receivable subsidiary ledger. What should the total be in the Accounts Receivable Control Total? Solution Accounts Payable Control Total is: 1,362 + 4,468 + 8,167 = 13,997 Accounts Receivable Control Total is: 2,250 + 0 + 1,500 + 8,160 = 11,910 Special Journals Instead of having just one general journal, companies group transactions of the same kind together and record them in special journals rather than in the general journal. This makes it easier and more efficient to find a specific type of transaction and speeds up the process of posting these transactions. In each special journal, all transactions are totaled at the end of the month, and these totals are posted to the general ledger. In addition, instead of one person entering all of the transactions in all of the journals, companies often assign a given special journal’s entries to one person. The relationship between the special journals, the general journal, and the general ledger can be seen in Figure 7.8 . Most companies have four special journals, but there can be more depending on the business needs. The four main special journals are the sales journal , purchases journal , cash disbursements journal , and cash receipts journal . These special journals were designed because some journal entries occur repeatedly. For example, selling goods for cash is always a debit to Cash and a credit to Sales recorded in the cash receipts journal. Likewise, we would record a sale of goods on credit in the sales journal, as a debit to accounts receivable and a credit to sales. Companies using a perpetual inventory system also record a second entry for a sale with a debit to cost of goods sold and a credit to inventory. You can see sample entries in Figure 7.9 . Note there is a column to enter the date the transaction took place; a column to indicate the customer to whom the transaction pertains; an invoice number that should match the number on the invoice given (in paper or electronically) to the customer; a reference box that indicates the transaction has been posted to the customer’s account and can include something as simple as a check mark or a code that links the transaction to other journals and ledgers; and the last two columns that indicate the accounts and amounts debited and credited. Purchases of inventory on credit would be recorded in the purchases journal ( Figure 7.10 ) with a debit to Merchandise Inventory and a credit to Accounts Payable. Paying bills is recorded in the cash disbursements journal ( Figure 7.11 ) and is always a debit to Accounts Payable (or another payable or expense) and a credit to Cash. The receipt of cash from the sale of goods, as payment on accounts receivable or from other transactions, is recorded in a cash receipts journal ( Figure 7.12 ) with a debit to cash and a credit to the source of the cash, whether that is from sales revenue, payment on an account receivable, or some other account. Table 7.1 summarizes the typical transactions in the special journals previously illustrated. Types and Purposes of Special Journals Journal Name Journal Purpose Account(s) Debited Account(s) Credited Sales Journal Sales on credit Accounts Receivable, Cost of Goods Sold Sales, Inventory Purchases Journal Purchases on credit Inventory Accounts Payable Cash Disbursements Journal Paying cash Could be: Accounts Payable, or other accounts Cash Cash Receipts Journal Receiving cash Cash Could be: Sales, Accounts Receivable, or other accounts General Journal Any transaction not covered previously; adjusting and closing entries Could be: Depreciation Expense Could be: Accumulated Depreciation Table 7.1 How will you remember all of this? Remember, “Cash Is King,” so we consider cash transactions first. If you receive cash, regardless of the source of the transaction, and even if it is only a part of the transaction, it goes in the cash receipts journal . For example, if the company made a sale for $1,000 and the customer gave $300 in cash and promised to pay the remaining balance in the future, the entire transaction would go into the cash receipts journal, because some cash was received, even if it was only part of a transaction. You could not split this journal entry between two journals, because each transaction’s debits must equal the credits or else your journal totals will not balance at the end of the month. You might consider splitting this transaction into two separate transactions and considering it a cash sale for $300 and a sale on account for $700, but that would also be inappropriate. Although the balances in the general ledger accounts would technically be correct if you did that, this is not the right approach. Good internal control dictates that this is a single transaction, associated with one invoice number on a given date, and should be recorded in its entirety in a single journal, which in this case is the cash receipts journal. If any cash is received, even if it is only a part of the transaction, the entire transaction is entered in the cash receipts journal. For this example, the transaction entered in the cash receipts journal would have a debit to cash for $300, a debit to Accounts Receivable for $700, and a credit to Sales for $1,000. If you pay cash (usually by writing a check), for any reason, even if it is only a part of the transaction, the entire transaction is recorded in the cash disbursements journal . For example, if the company purchased a building for $500,000 and gave a check for $100,000 as a down payment, the entire transaction would be recorded in the cash disbursements journal as a credit to cash for $100,000, a credit to mortgage payable for $400,000, and a debit to buildings for $500,000. If the transaction does not involve cash, it will be recorded in one of the other special journals. If it is a credit sale (also known as a sale on account), it is recorded in the sales journal. If it is a credit purchase (also known as a purchase on account), it is recorded in the purchases journal. If it is none of the above, it is recorded in the general journal. Continuing Application Accounting Information Systems Let’s consider what Gearhead Outfitters ’ accounting information system might look like. What information will company management find important? Likewise, what information might external users of Gearhead’s financial reports need? Do regulatory requirements dictate what Gearhead needs to track in its accounting system? Gearhead will want to know its financial position, results of operations, and cash flows. Such data will help management make decisions about the company. Likewise, external users want this data (balance sheet, income statement, and statement of cash flows) to make decisions such as whether or not to extend credit to Gearhead . To keep accurate records, company operations must be considered. For example, inventory is purchased, sales are made, customers are billed, cash is collected, employees work and need to be paid, and other expenses are incurred. All of these operations involve different recording processes. Inventory will require a purchases journal. Sales will require a sales journal, cash receipts journal, and accounts receivable subsidiary ledger (discussed later) journal. Payroll and other disbursements will require their own journals to accurately track transactions. Such journals allow a company to record accounting information and generate financial statements. The data also provides management with the information needed to make sound business decisions. For example, subsidiary ledgers, such as the accounts receivable ledger, provide data about the aging and collectability of receivables. Thus, the proper design, implementation, and maintenance of the accounting information system are vital to a company’s sustainability. What other questions can be answered through the analysis of information gathered by the accounting information system? Think in terms of the timing of inventory orders and cash flow needs. Is there nonfinancial information to extract from the accounting system? An accounting information system should provide the information needed for a business to meet its goals. Subsidiary Ledgers In addition to the four special journals, there are two special ledgers, the accounts receivable subsidiary ledger and the accounts payable subsidiary ledger. The accounts receivable subsidiary ledger gives details about each person who owes the company money, as shown in Figure 7.13 . Each colored block represents an individual’s account and shows only the amount that person owes the company. Notice that the subsidiary ledger provides the date of the transaction and a reference column to link the transaction to the same information posted in one of the special journals (or general journal if special journals are not used)—this reference is usually a code that references the special journal such as SJ for the sales special journal, as well as the amounts owed in the debit column and the payments made in the credit column. The amounts owed by all of the individuals, as indicated in the subsidiary ledger, are added together to form the accounts receivable control total, and this should equal the Accounts Receivable balance reported in the general ledger as shown in Figure 7.14 . Key points about the accounts receivable subsidiary ledger are: Accounts Receivable in the general ledger is the total of all of the individual account totals that are listed in the accounts receivable subsidiary ledger. All of the amounts owed to the company in the accounts receivable subsidiary ledger must equal the amounts in the accounts receivable general ledger account. Ethical Considerations Subsidiary Ledger Fraud 6 Subsidiary ledgers have to balance and agree with the general ledger. Accountants using QuickBooks and other accounting systems may not have to perform this step, because in these systems the subsidiary ledger updates the general ledger automatically. However, a dishonest person might manipulate accounting records by recording a smaller amount of cash receipts in the control account than is recorded on the subsidiary ledger cards. The ethical accountant must be vigilant to ensure that the ledgers remain balanced and that proper internal controls are in place to ensure the soundness of the accounting system. 6 Joseph R. Dervaes. “Accounts Receivable Fraud, Part Five: Other Accounting Manipulations.” Fraud Magazine . July/August, 2004. http://www.fraud-magazine.com/article.aspx?id=4294967822 The accounts payable subsidiary ledger holds the details about all of the amounts a company owes to people and/or companies. In the accounts payable subsidiary ledger, each vendor (the person or company from whom you purchased inventory or other items) has an account that shows the details of all transactions. Similar to the accounts receivable subsidiary ledger, the purchases subsidiary journal indicates the date on which a transaction took place; a reference column used in the same manner as previously described for accounts receivable subsidiary ledgers; and finally, the subsidiary ledger shows the amount charged or the amount paid. Following are the transactions for ABC Inc. and XYZ Inc. The final balance indicated on each subsidiary purchases journal shows the amount the company owes ABC and XYZ. If the two amounts are added together, the company owes $305 in total to the two companies. The $305 is the amount that will show in the Accounts Payable general ledger account. Your Turn Using the Accounts Payable Subsidiary Ledger Find the balance in each account in the accounts payable subsidiary ledger that follows. Note that each vendor account has a unique account number or AP No. Solution 7.3 Analyze and Journalize Transactions Using Special Journals Accounting information systems were paper based until the introduction of the computer, so special journals were widely used. When accountants used a paper system, they had to write the same number in multiple places and thus could make a mistake. Now that most businesses use digital technology, the step of posting to journals is performed by the accounting software. The transactions themselves end up on transaction files rather than in paper journals, but companies still print or make available on the screen something that closely resembles the journals. Years ago, all accounting record keeping was manual. If a company had many transactions, that meant many journal entries to be recorded in the general journal. People soon realized that certain types of transactions occurred more frequently than any other types of transaction, so to save time, they designed a special journal for each type that occurs frequently (e.g., credit sales, credit purchases, receipts of cash, and disbursements of cash). We would enter these four types of transactions into their own journals, respectively, rather than in the general journal. Thus, in addition to the general journal, we also have the sales journal, cash receipts journal, purchases journal, and cash disbursements journals. The main difference between special journals using the perpetual inventory method and the periodic inventory method is that the sales journal in the perpetual method, as you have seen in the prior examples in the chapter, will have a column to record a debit to Cost of Goods Sold and a credit to Inventory. In the purchases journal, using the perpetual method will require we debit Inventory instead of Purchases. Another difference is that the perpetual method will include freight charges in the Inventory account, while the periodic method will have a special Freight-in account that will be added when Cost of Goods Sold will be computed. For a refresher on perpetual versus periodic and related accounts such as freight-in, please refer to Merchandising Transactions . Think It Through Which Journal? If you received a check from Mr. Jones for $500 for work you performed last week, which journal would you use to record receipt of the amount they owed you? What would be recorded? The Sales Journal The sales journal is used to record sales on account (meaning sales on credit or credit sale). Selling on credit always requires a debit to Accounts Receivable and a credit to Sales. Because every credit sales transaction is recorded in the same way, recording all of those transactions in one place simplifies the accounting process. Figure 7.15 shows an example of a sales journal. Note there is a single column for both the debit to Accounts Receivable and the credit to Sales, although we need to post to both Accounts Receivable and Sales at the end of each month. There is also a single column for the debit to Cost of Goods Sold and the credit to Merchandise Inventory, though again, we need to post to both of those. In addition, for companies using the perpetual inventory method, there is another column representing a debit to Cost of Goods Sold and a credit to Merchandise Inventory, since two entries are made to record a sale on account under the perpetual inventory method. The information in the sales journal was taken from a copy of the sales invoice, which is the source document representing the sale. The sales invoice number is entered so the bookkeeper could look up the sales invoice and assist the customer. One benefit of using special journals is that one person can work with this journal while someone else works with a different special journal. At the end of the month, the bookkeeper, or computer program, would total the A/R Dr and Sales Cr column and post the amount to the Accounts Receivable control account in the general ledger and the Sales account in the general ledger. The Accounts Receivable control account in the general ledger is the total of all of the amounts customers owed the company. Also at the end of the month, the total debit in the cost of goods sold column and the total credit to the merchandise inventory column would be posted to their respective general ledger accounts. The company could have made these entries in the general journal instead of the special journal, but if it had, this would have likely caused the sales transactions to be separated from each other and spread throughout the journal, making it harder to find and keep track of them. When a sales journal is used, if the company is one where sales tax is collected from the customer, then the journal entry would be a debit to Accounts Receivable and a credit to Sales and Sales Tax Payable, and this would require an additional column in the sales journal to record the sales tax. For example, a $100 sale with $10 additional sales tax collected would be recorded as a debit to Accounts Receivable for $110, a credit to Sales for $100 and a credit to Sales Tax Payable for $10. The use of a reference code in any of the special journals is very important. Remember, after a sale is recorded in the sales journal, it is posted to the accounts receivable subsidiary ledger, and the use of a reference code helps link the transactions between the journals and ledgers. Recall that the accounts receivable subsidiary ledger is a record of each customer’s account. It looked like Figure 7.16 for Baker Co. Using the reference information, if anyone had a question about this entry, he or she would go to the sales journal, page 26, transactions #45321 and #45324. This helps to create an audit trail, or a way to go back and find the original documents supporting a transaction. Your Turn Which Journal Do You Use? Match each of the transactions in the right column with the appropriate journal from the left column. A. Purchases journal i. Sales on account B. Cash receipts journal ii. Adjusting entries C. Cash disbursements journal iii. Receiving cash from a charge customer D. Sales journal iv. Buying inventory on credit E. General journal v. Paying the electric bill Solution A. iv; B. iii; C. v; D. i; E. ii. Comprehensive Example Let us return to the sales journal, shown in Figure 7.17 that includes information about Baker Co. as well as other companies with whom the company does business. At the end of the month, the total Sales on credit were $2,775. The transactions would be posted in chronological order in the sales journal. As you can see, the first transaction is posted to Baker Co., the second one to Alpha Co., then Tau Inc., and then another to Baker Co. On the date each transaction is posted in the sales journal, the appropriate information would be posted in the subsidiary ledger for each of the customers. As an example, on January 3, amounts related to invoices 45321 and 45322 are posted to Baker’s and Alpha’s accounts, respectively, in the appropriate subsidiary ledger. At the end of the month, the total of $2,775 would be posted to the Accounts Receivable control account in the general ledger. Baker Co.’s account in the subsidiary ledger would show that they owe $1,450; Alpha Co. owes $625; and Tau Inc. owes $700 ( Figure 7.18 ). At the end of the month, we would post the totals from the sales journal to the general ledger ( Figure 7.19 ). Altogether, the three individual accounts owe the company $2,775, which is the amount shown in the Accounts Receivable control account. It is called a control total because it helps keep accurate records, and the total in the accounts receivable must equal the balance in Accounts Receivable in the general ledger. If the amount of all the individual accounts receivable accounts did not add up to the total in the Accounts Receivable general ledger/control account, it would indicate that we made a mistake. Figure 7.20 shows how the accounts and amounts are posted. The Cash Receipts Journal When the customer pays the amount owed, (generally using a check), bookkeepers use another shortcut to record its receipt. They use a second special journal, the cash receipts journal . The cash receipts journal is used to record all receipts of cash (recorded by a debit to Cash). In the preceding example, if Baker Co. paid the $1,450 owed, there would be a debit to Cash for $1,450 and a credit to Accounts Receivable. A notation would be made in the reference column to indicate the payment had been posted to Baker Co.’s accounts receivable subsidiary ledger. After Baker Co.’s payment, the cash receipts journal would appear as in Figure 7.21 . And the accounts receivable subsidiary ledger for Baker Co. would also show the payment had been posted ( Figure 7.22 ). In the cash receipts journal, the credit can be to Accounts Receivable when a customer pays on an account, or Sales, in the case of a cash sale, or to some other account when cash is received for other reasons. For example, if we overpaid our electric bill, we could get a refund check in the mail. We would use the cash receipts journal because we are receiving cash, but the credit would be to our Utility Expense account. If you look at the example in Figure 7.23 , you see that there is no column for Utility Expense, so how would it be recorded? We would use some generic column title such as “other” to represent those cash transactions in the subsidiary ledger though the specific accounts would actually be identified by account number in the special journal. We would look up the account number for Utility Expense and credit the account for the amount of the check. If we received a refund from the electric company on January 28 in the amount of $100, we would find the account number for utility expense (say it is 615) and record it. At the end of the month, we total the Cash column in the cash receipts journal and debit the Cash account in the general ledger for the total. In this case there were two entries in the cash receipts journal, the cash received from Baker and the refund check for an overpayment on utilities for a total cash received and recorded in the cash receipts journal of $1,550, as shown in Figure 7.24 . Any accounts used in the Other Accounts column must be entered separately in the general ledger to the appropriate account. Figure 7.25 shows how the refund would be posted to the utilities expense account in the general ledger. The Cash Disbursements Journal Many transactions involve cash. We enter all cash received into the cash receipts journal, and we enter all cash payments into the cash disbursements journal , sometimes also known as the cash payments journal . Good internal control dictates the best rule is that all cash received by a business should be deposited, and all cash paid out for monies owed by the business should be made by check. Money paid out is recorded in the cash disbursements journal, which is generally kept in numerical order by check number and includes all of the checks recorded in the checkbook register. If we paid this month’s phone bill of $135 with check #4011, we would enter it as shown in Figure 7.26 in the cash disbursements journal. The total of all of the cash disbursements for the month would be recorded in the general ledger Cash account ( Figure 7.27 ) as follows. Note that the information for both the cash receipts journal and the cash disbursements journal are recorded in the general ledger Cash account. The Purchases Journal Many companies enter only purchases of inventory on account in the purchases journal . Some companies also use it to record purchases of other supplies on account. However, in this chapter we use the purchases journal for purchases of inventory on account, only. It will always have a debit to Merchandise Inventory if you are using the perpetual inventory method and a credit to Accounts Payable, or a debit to Purchases and a credit to Accounts Payable if using the periodic inventory method. It is similar to the sales journal because it has a corresponding subsidiary ledger, the accounts payable subsidiary ledger. Since the purchases journal is only for purchases of inventory on account, it means the company owes money. To keep track of whom the company owes money to and when payment is due, the entries are posted daily to the accounts payable subsidiary ledger. Accounts Payable in the general ledger becomes a control account just like Accounts Receivable. If we ordered inventory from Jones Mfg. (account number 789) using purchase order #123 and received the bill for $250, this would be recorded in the purchases journal as shown in Figure 7.28 . The posting reference would be to indicate that we had entered the amount in the accounts payable subsidiary ledger ( Figure 7.29 ). The total of all accounts payable subsidiary ledgers would be posted at the end of the month to the general ledger Accounts Payable control account. The sum of all the subsidiary ledgers must equal the amount reported in the general ledger. General Journal Why use a general journal if we have all the special journals? The reason is that some transactions do not fit in any special journal. In addition to the four special journals presented previously (sales, cash receipts, cash disbursements, and purchases), some companies also use a special journal for Sales returns and allowances and another special journal for Purchase returns and allowances if they have many sales returns and purchase returns transactions. However, most firms enter those transactions in the general journal, along with other transactions that do not fit the description of the specific types of transactions contained in the four special journals. The general journal is also necessary for adjusting entries (such as to recognize depreciation, prepaid rent, and supplies that we have consumed) and closing entries. Your Turn Using the Sales and Cash Receipts Journals You own and operate a business that sells goods to other businesses. You allow established customers to buy goods from you on account, meaning you let them charge purchases and offer terms of 2/10, n/30. Record the following transactions in the sales journal and cash receipts journal: Jan. 3 Sales on credit to VJ Armitraj, Ltd., amount of $7,200, Invoice # 317745 Jan. 9 Sales on credit to M. Baghdatis Inc., amount of $5,200, Invoice # 317746 Jan. 16 Receive $7,200 from VJ Armitraj, Ltd. (did not receive during the discount period) Jan. 17 Sales on credit to A. Ashe Inc., amount of $3,780, Invoice #317747 Jan. 18 Receive the full amount owed from M. Baghdatis Inc. within the discount period Solution Ensure that the total of all individual accounts receivable equals the total of accounts receivable, or: 0 + $3,780 + 0 = $3,780. 7.4 Prepare a Subsidiary Ledger Now that you have seen four special journals and two special ledgers, it is time to put all the pieces together. Record the following transactions for Store Inc. in the special journals and post to the general ledger provided. Also post to the subsidiary ledgers provided. Beginning account balances are shown below. Use the perpetual inventory method and the gross method of dealing with sales terms. First, enter these transactions manually by creating the relevant journals and subsidiary ledgers. Then enter them using QuickBooks. Transactions for Store Inc. Jan. 2 Issued check #629 for January store rent: $350.00 Jan. 3 Received check from PB&J in payment for December sale on credit, $915.00 Jan. 4 Issued check #630 to D & D in payment for December purchase on credit of $736.00 Jan. 5 Sold goods for $328.00 to Jones Co. on credit, Invoice #234 (Note: COGS is $164) Jan. 6 Bought goods from BSA for $4,300.00, Purchase Order #71, terms: 2/10, net/30 Jan. 8 Sold goods on credit to Black & White Inc. for $2,100, Invoice #235, terms: 1/10, net/30 (Note: COGS is $1,050) Jan. 9 Issued check #63 for telephone bill received today, $72.00 Jan. 10 Issued check #632 to pay BSA in full, PO 71. Jan. 15 Received full payment from Black & White, Inc., Invoice #235 Jan. 20 Bought merchandise from Dow John, $525.00 payable in 30 days, Purchase Order #72 Jan. 26 Returned $100 of merchandise to Dow John, relating to Purchase Order #72 Jan. 31 Recorded cash sales for the month of $3,408 (Note: COGS is $1,704) Jan. 31 Recognized that half of the Prepaid Insurance has been consumed Table 7.2 Record all transactions using the sales journal, purchases journal, cash receipts journal, cash disbursements journal, and the general journal and post to the accounts receivable and accounts payable subsidiary ledgers. Then prepare a schedule of accounts receivable and a schedule of accounts payable. Explanation: Jan. 3 The company received payment from PB&J; thus, a cash receipt is recorded. Jan. 15 The company received payment on goods that were sold on Jan. 8 with credit terms if paid within the discount period. The payment was received within the discount period. Jan. 31 Cash sales are recorded. Explanation: Jan. 26 The company returns merchandise (inventory) previously purchased. Since the company is using the perpetual method, a credit is made to Inventory. Jan. 31 An adjusting entry is made to recognize insurance expense for the current month that had previously been prepaid. Explanation: Jan. 8 Sales on credit are recorded Explanation: Jan. 2 Rent for the month is paid. Jan. 4 Payment is made for inventory purchased on account in a prior month. Jan. 9 Paid the telephone bill. Jan. 10 Paid for inventory purchased earlier on account. The payment arrangement had credit terms; the invoice was paid within the time allowed, and the discount was taken. Explanation: Jan. 6 Inventory is purchased on account. Jan. 20 Inventory is purchased on account. At the end of the month, each of the previous journal totals are posted to the appropriate account in the general ledger, and any individual account postings, such as to Rent Expense (Jan. 2 transaction) would also be posted to the general ledger. Note that each account used by the company has its own account section in the general ledger. If you check Accounts Receivable in the general ledger, you see the balance is $2,989, and the balance in Accounts Payable is $6,071. If the numbers did not match, we would have to find out where the error was and then fix it. The purpose of keeping subsidiary ledger s is for accuracy and efficiency. They aid us in keeping accurate records. Since the total of the accounts receivable subsidiary ledger must agree with the balance shown in the accounts receivable general ledger account, the system helps us find mistakes. Since bookkeeping using ledgers is older than the United States, it was an ingenious way to double-check without having to actually do everything twice. It provided an internal control over record keeping. Today, computerized accounting information systems use the same method to store and total amounts, but it takes a lot less time. 7.5 Describe Career Paths Open to Individuals with a Joint Education in Accounting and Information Systems We use accounting information to make decisions about the business. Computer applications now provide so much data that data analytics is one of the newest career areas in business. Universities are beginning to offer degrees in data analysis. Software companies have created different applications to analyze data including SAS, Apache Hadoop, Apache Spark, SPSS, RapidMiner, Power BI, ACL, IDEA, and many more to help companies discover useful information from the transactions that occur. Big data refers to the availability of large amounts of data from various sources, including the internet. For example, social media sites contain tremendous amounts of data that marketing companies analyze to determine how popular a product is, and how best to market it. There is so much data to analyze that new ways of mining it for predictive value have evolved. Another emerging area involves cryptocurrency , or the use of a digital currency that uses encryption technologies that make these cryptocurrencies impossible to counterfeit. The use of cryptocurrency does not require a bank to transfer or clear funds as is the case with other currencies. Bitcoin is the most well-known cryptocurrency. Blockchain is the platform on which Bitcoin is built. Blockchain serves as a shared ledger for Bitcoin but is also the foundation of many other applications. Simply put, blockchain offers different parties to a transaction (e.g., a buyer and a seller) the opportunity to use a shared ledger rather than each having their own separate ledgers as is the case with traditional systems. Bitcoin is currently accepted by some large, well-known companies including PwC and EY (the two largest of the “big 4” accounting firms), and Overstock.com . Enterprise resource planning (ERP) software is a collection of integrated programs that track all operations in a company, from payroll to accounts payable, manufacturing, and maintaining electronic connections with suppliers. For example, companies that sell goods to Walmart , have access to Walmart’s electronic inventory records so the vendors can make sure Walmart has the right amount of goods on hand. Having such a close relationship brings rewards. They will probably receive payment sooner, using EFT (electronic funds transfer). The use of accounting information system s (AISs) has drastically changed the way we prepare tax returns. Software is now written to walk anyone through preparing his or her own tax return using an expert system . An expert system asks questions like: are you married? If the answer is yes, the software knows to use the married tax tables, and if the answer is no, it uses the single tables. Based on this answer, it will know what kind of question to ask next. Accountants who understand expert systems and tax will be writing and auditing tax software programs. Firms are also developing and using artificial intelligence (AI) systems to perform tasks previously performed by accounting professionals, but now are freeing up the professionals to perform higher-level tasks requiring analysis and judgment. Finally, security of all of this available data is a very important issue, and there are a number of career paths and certifications that information technology professionals can attain. The Information Systems Audit and Control Association (ISACA) offers several certifications including Certified Information Systems Auditor (CISA) , Certified in Risk and Information System Controls (CRISC) , Certified Information Security Manager (CISM) , and others. There is so much technology that we are inundated with more information than we can use. Because the information is being generated by a machine, we generally trust the computation (although there are cases where a bug in the program can even cause problems with simple math), but we also know the old saying, “garbage in, garbage out.” The computer does not always know that your typo is garbage. If you enter the wrong number, the system processes it as if it were the right number. That means we have to build some way into the program to control what is input into the system. For example, if you fill out a form online and it asks for your zip code, does it let you enter just four digits? No—the computer knows that it should only go to the next step if you enter five digits. However, you can enter the wrong digits and it might not catch it. It is critical that we build as many internal controls into our computerized systems as possible so that we can find errors at the input stage before they get into our system. In other words, by using these “preventive” controls, we do not allow “garbage” data to get into our system. Computerized AISs have also brought changes to the audit trail. In the past, accountants had a set of books that were paper based. You could see where a transaction was recorded and posted (and see if it had been erased). Once you enter it into a computer, it becomes part of an electronic audit trail, but the trail is only as good as the program that runs it. The screen could show you one number, but the system could be working with a different number all together. In fact, there have been criminal cases in which people wrote programs to cover up fraud. One such program functioned so that when an item was scanned, the correct amount displayed to the customer, but it was recorded in the books as a smaller amount, so the company paid less in sales tax and much less in income tax. AISs have become more important because information and technology are more important. Concepts In Practice Is Technology Always Better? Technology allows one person to do a job that once took a dozen people to do. However, that can also lead to problems. For example, years ago, one person working in the accounts receivable department at Burlington Industries would have been in charge of a few customers. If those customers were not paying their bills on time, a person would be aware of it. Today, one person might be in charge of all accounts receivable. That person may not have time to call individual customers, so everything is preprogrammed. If the customer wanted to place a large order that caused them to go over their limit, the software would deny it instead of having a person weigh the risk of extending more credit. A risk inherent in an AIS is that one person has access to a lot of information, and sometimes the information crosses department lines. Companies have to figure out ways to mitigate the risk, because AISs are truly essential to businesses today, especially with the growth of e-business and e-commerce. Think of the different business processes when a purchase is made through Amazon.com . Their AIS must be able to access inventory records, access customer information and records, process credit cards, calculate delivery dates, handle coupons or discounts, and remember where to ship the goods. Amazon would not be what it is today without all of its systems working together. Seeing what Amazon has accomplished opens the door for other companies to follow, and they will need people who understand the system. Forensic accounting involves the use of accounting skills to inspect the accounting records in order to determine if fraud or embezzlement have occurred. Many universities are offering forensic accounting degrees to prepare students who can testify to criminal activity present in the accounting records. Concepts In Practice The Founding of the Securities and Exchange Commission In 1933 and 1934, the US Congress passed two acts that established the Securities and Exchange Commission (SEC) , giving it the right to regulate and enforce the regulations concerning commerce in the United States. The website of the SEC (https://www.SEC.gov/) allows you to view all public company financial reporting and provides a link to all current litigation against individuals and companies that have been accused of breaking an SEC regulation. If you go to the site and look for the Litigation Releases section, you can click on individual cases and find that some cases of fraud involve the use of an accounting information system. The Patriot Act also came out of the 9/11 attacks (signed October 26, 2001). The letters in Patriot stand for the following: providing appropriate tools required to intercept and obstruct terrorism. The goal of the act was to prevent any other attacks on the United States by allowing enhanced surveillance procedures. The act gave law enforcement officials the right to access computers to track IP addresses, websites visited, credit card information provided electronically, and so on, in an effort to uncover terrorism before an attack was made. Several parts of the act call for banks to report suspected money laundering activities. Money laundering is an attempt to hide the facts of the original transaction and would involve an accountant. If you were selling drugs for cash and then tried to deposit that much cash in a bank, the bank would report it, so you would try to cover up where the cash came from and run it through a legitimate company. That is money laundering. The Patriot Act also includes a section requiring auditors to verify that a company has controls in place to prevent an attack on its accounting information system and that the company has a disaster plan including backup records in case of a disaster. The AIS enables a company to record all of its business transactions. Systems are different depending on the company’s needs. The AIS holds a lot of the information used to run a business. One system can provide everything needed for external reporting to government agencies involving payroll and income taxation. The same system can provide the data needed for managerial analysis used for pricing, budgeting, decision-making, and efficiency studies. Every company is required to keep records of their financial activity, and this means job security for people who are knowledgeable about AISs.
psychology
Summary 16.1 Mental Health Treatment: Past and Present It was once believed that people with psychological disorders, or those exhibiting strange behavior, were possessed by demons. These people were forced to take part in exorcisms, were imprisoned, or executed. Later, asylums were built to house the mentally ill, but the patients received little to no treatment, and many of the methods used were cruel. Philippe Pinel and Dorothea Dix argued for more humane treatment of people with psychological disorders. In the mid-1960s, the deinstitutionalization movement gained support and asylums were closed, enabling people with mental illness to return home and receive treatment in their own communities. Some did go to their family homes, but many became homeless due to a lack of resources and support mechanisms. Today, instead of asylums, there are psychiatric hospitals run by state governments and local community hospitals, with the emphasis on short-term stays. However, most people suffering from mental illness are not hospitalized. A person suffering symptoms could speak with a primary care physician, who most likely would refer him to someone who specializes in therapy. The person can receive outpatient mental health services from a variety of sources, including psychologists, psychiatrists, marriage and family therapists, school counselors, clinical social workers, and religious personnel. These therapy sessions would be covered through insurance, government funds, or private (self) pay. 16.2 Types of Treatment Psychoanalysis was developed by Sigmund Freud. Freud’s theory is that a person’s psychological problems are the result of repressed impulses or childhood trauma. The goal of the therapist is to help a person uncover buried feelings by using techniques such as free association and dream analysis. Play therapy is a psychodynamic therapy technique often used with children. The idea is that children play out their hopes, fantasies, and traumas, using dolls, stuffed animals, and sandbox figurines. In behavior therapy, a therapist employs principles of learning from classical and operant conditioning to help clients change undesirable behaviors. Counterconditioning is a commonly used therapeutic technique in which a client learns a new response to a stimulus that has previously elicited an undesirable behavior via classical conditioning. Principles of operant conditioning can be applied to help people deal with a wide range of psychological problems. Token economy is an example of a popular operant conditioning technique. Cognitive therapy is a technique that focuses on how thoughts lead to feelings of distress. The idea behind cognitive therapy is that how you think determines how you feel and act. Cognitive therapists help clients change dysfunctional thoughts in order to relieve distress. Cognitive-behavioral therapy explores how our thoughts affect our behavior. Cognitive-behavioral therapy aims to change cognitive distortions and self-defeating behaviors. Humanistic therapy focuses on helping people achieve their potential. One form of humanistic therapy developed by Carl Rogers is known as client-centered or Rogerian therapy. Client-centered therapists use the techniques of active listening, unconditional positive regard, genuineness, and empathy to help clients become more accepting of themselves. Often in combination with psychotherapy, people can be prescribed biologically based treatments such as psychotropic medications and/or other medical procedures such as electro-convulsive therapy. 16.3 Treatment Modalities There are several modalities of treatment: individual therapy, group therapy, couples therapy, and family therapy are the most common. In an individual therapy session, a client works one-on-one with a trained therapist. In group therapy, usually 5–10 people meet with a trained group therapist to discuss a common issue (e.g., divorce, grief, eating disorders, substance abuse, or anger management). Couples therapy involves two people in an intimate relationship who are having difficulties and are trying to resolve them. The couple may be dating, partnered, engaged, or married. The therapist helps them resolve their problems as well as implement strategies that will lead to a healthier and happier relationship. Family therapy is a special form of group therapy. The therapy group is made up of one or more families. The goal of this approach is to enhance the growth of each individual family member and the family as a whole. 16.4 Substance-Related and Addictive Disorders: A Special Case Addiction is often viewed as a chronic disease that rewires the brain. This helps explain why relapse rates tend to be high, around 40%–60% (McLellan, Lewis, & O’Brien, & Kleber, 2000). The goal of treatment is to help an addict stop compulsive drug-seeking behaviors. Treatment usually includes behavioral therapy, which can take place individually or in a group setting. Treatment may also include medication. Sometimes a person has comorbid disorders, which usually means that they have a substance-related disorder diagnosis and another psychiatric diagnosis, such as depression, bipolar disorder, or schizophrenia. The best treatment would address both problems simultaneously. 16.5 The Sociocultural Model and Therapy Utilization The sociocultural perspective looks at you, your behaviors, and your symptoms in the context of your culture and background. Clinicians using this approach integrate cultural and religious beliefs into the therapeutic process. Research has shown that ethnic minorities are less likely to access mental health services than their White middle-class American counterparts. Barriers to treatment include lack of insurance, transportation, and time; cultural views that mental illness is a stigma; fears about treatment; and language barriers.
Chapter Outline 16.1 Mental Health Treatment: Past and Present 16.2 Types of Treatment 16.3 Treatment Modalities 16.4 Substance-Related and Addictive Disorders: A Special Case 16.5 The Sociocultural Model and Therapy Utilization Introduction What comes to mind when you think about therapy for psychological problems? You might picture someone lying on a couch talking about his childhood while the therapist sits and takes notes, à la Sigmund Freud. But can you envision a therapy session in which someone is wearing virtual reality headgear to conquer a fear of snakes? In this chapter, you will see that approaches to therapy include both psychological and biological interventions, all with the goal of alleviating distress. Because psychological problems can originate from various sources—biology, genetics, childhood experiences, conditioning, and sociocultural influences—psychologists have developed many different therapeutic techniques and approaches. The Ocean Therapy program shown in Figure 16.1 uses multiple approaches to support the mental health of veterans in the group.
[ { "answer": { "ans_choice": 1, "ans_text": "medieval priests" }, "bloom": null, "hl_context": "<hl> In the 19th century , Dorothea Dix led reform efforts for mental health care in the United States ( Figure 16.6 ) . <hl> She investigated how those who are mentally ill and poor were cared for , and she discovered an underfunded and unregulated system that perpetuated abuse of this population ( Tiffany , 1891 ) . Horrified by her findings , Dix began lobbying various state legislatures and the U . S . Congress for change ( Tiffany , 1891 ) . Her efforts led to the creation of the first mental asylums in the United States . <hl> In the late 1700s , a French physician , Philippe Pinel , argued for more humane treatment of the mentally ill . <hl> He suggested that they be unchained and talked to , and that ’ s just what he did for patients at La Salpêtrière in Paris in 1795 ( Figure 16.5 ) . Patients benefited from this more humane treatment , and many were able to leave the hospital . For much of history , the mentally ill have been treated very poorly . It was believed that mental illness was caused by demonic possession , witchcraft , or an angry god ( Szasz , 1960 ) . <hl> For example , in medieval times , abnormal behaviors were viewed as a sign that a person was possessed by demons . <hl> <hl> If someone was considered to be possessed , there were several forms of treatment to release spirits from the individual . <hl> The most common treatment was exorcism , often conducted by priests or other religious figures : Incantations and prayers were said over the person ’ s body , and she may have been given some medicinal drinks . Another form of treatment for extreme cases of mental illness was trephining : A small hole was made in the afflicted individual ’ s skull to release spirits from the body . Most people treated in this manner died . In addition to exorcism and trephining , other practices involved execution or imprisonment of people with psychological disorders . Still others were left to be homeless beggars . Generally speaking , most people who exhibited strange behaviors were greatly misunderstood and treated cruelly . The prevailing theory of psychopathology in earlier history was the idea that mental illness was the result of demonic possession by either an evil spirit or an evil god because early beliefs incorrectly attributed all unexplainable phenomena to deities deemed either good or evil .", "hl_sentences": "In the 19th century , Dorothea Dix led reform efforts for mental health care in the United States ( Figure 16.6 ) . In the late 1700s , a French physician , Philippe Pinel , argued for more humane treatment of the mentally ill . For example , in medieval times , abnormal behaviors were viewed as a sign that a person was possessed by demons . If someone was considered to be possessed , there were several forms of treatment to release spirits from the individual .", "question": { "cloze_format": "____ does not support the humane and improved treatment of mentally ill persons.", "normal_format": "Who of the following does not support the humane and improved treatment of mentally ill persons?", "question_choices": [ "Philippe Pinel", "medieval priests", "Dorothea Dix", "All of the above" ], "question_id": "fs-idm9640640", "question_text": "Who of the following does not support the humane and improved treatment of mentally ill persons?" }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 0, "ans_text": "deinstitutionalization" }, "bloom": "1", "hl_context": "Starting in 1954 and gaining popularity in the 1960s , antipsychotic medications were introduced . These proved a tremendous help in controlling the symptoms of certain psychological disorders , such as psychosis . Psychosis was a common diagnosis of individuals in mental hospitals , and it was often evidenced by symptoms like hallucinations and delusions , indicating a loss of contact with reality . Then in 1963 , Congress passed and John F . Kennedy signed the Mental Retardation Facilities and Community Mental Health Centers Construction Act , which provided federal support and funding for community mental health centers ( National Institutes of Health , 2013 ) . This legislation changed how mental health services were delivered in the United States . <hl> It started the process of deinstitutionalization , the closing of large asylums , by providing for people to stay in their communities and be treated locally . <hl> In 1955 , there were 558,239 severely mentally ill patients institutionalized at public hospitals ( Torrey , 1997 ) . By 1994 , by percentage of the population , there were 92 % fewer hospitalized individuals ( Torrey , 1997 ) .", "hl_sentences": "It started the process of deinstitutionalization , the closing of large asylums , by providing for people to stay in their communities and be treated locally .", "question": { "cloze_format": "The process of closing large asylums and providing for people to stay in the community to be treated locally is known as ________.", "normal_format": "What is the process of closing large asylums and providing for people to stay in the community to be treated locally known as?", "question_choices": [ "deinstitutionalization", "exorcism", "deactivation", "decentralization" ], "question_id": "fs-idm83080272", "question_text": "The process of closing large asylums and providing for people to stay in the community to be treated locally is known as ________." }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 0, "ans_text": "involuntary" }, "bloom": "1", "hl_context": "Some people seek therapy because the criminal justice system referred them or required them to go . For some individuals , for example , attending weekly counseling sessions might be a condition of parole . If an individual is mandated to attend therapy , she is seeking services involuntarily . <hl> Involuntary treatment refers to therapy that is not the individual ’ s choice . <hl> Other individuals might voluntarily seek treatment . Voluntary treatment means the person chooses to attend therapy to obtain relief from symptoms .", "hl_sentences": "Involuntary treatment refers to therapy that is not the individual ’ s choice .", "question": { "cloze_format": "Joey was convicted of domestic violence. As part of his sentence, the judge has ordered that he attend therapy for anger management. This is considered ________ treatment.", "normal_format": "Joey was convicted of domestic violence. As part of his sentence, the judge has ordered that he attend therapy for anger management. What treatment is this considered to be?", "question_choices": [ "involuntary", "voluntary", "forced", "mandatory" ], "question_id": "fs-idm100302928", "question_text": "Joey was convicted of domestic violence. As part of his sentence, the judge has ordered that he attend therapy for anger management. This is considered ________ treatment." }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 2, "ans_text": "are an imminent threat to themselves or others" }, "bloom": null, "hl_context": "Today , instead of asylums , there are psychiatric hospitals run by state governments and local community hospitals focused on short-term care . In all types of hospitals , the emphasis is on short-term stays , with the average length of stay being less than two weeks and often only several days . This is partly due to the very high cost of psychiatric hospitalization , which can be about $ 800 to $ 1000 per night ( Stensland , Watson , & Grazier , 2012 ) . Therefore , insurance coverage often limits the length of time a person can be hospitalized for treatment . <hl> Usually individuals are hospitalized only if they are an imminent threat to themselves or others . <hl>", "hl_sentences": "Usually individuals are hospitalized only if they are an imminent threat to themselves or others .", "question": { "cloze_format": "Today, most people with psychological problems are not hospitalized. Typically they are only hospitalized if they ________.", "normal_format": "Today, most people with psychological problems are not hospitalized. When are they only typically hospitalized?", "question_choices": [ "have schizophrenia", "have insurance", "are an imminent threat to themselves or others", "require therapy" ], "question_id": "fs-idm9089504", "question_text": "Today, most people with psychological problems are not hospitalized. Typically they are only hospitalized if they ________." }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 0, "ans_text": "cognitive therapy" }, "bloom": null, "hl_context": "<hl> Cognitive therapy is a form of psychotherapy that focuses on how a person ’ s thoughts lead to feelings of distress . <hl> <hl> The idea behind cognitive therapy is that how you think determines how you feel and act . <hl> Cognitive therapists help their clients change dysfunctional thoughts in order to relieve distress . They help a client see how they misinterpret a situation ( cognitive distortion ) . For example , a client may overgeneralize . Because Ray failed one test in his Psychology 101 course , he feels he is stupid and worthless . These thoughts then cause his mood to worsen . Therapists also help clients recognize when they blow things out of proportion . Because Ray failed his Psychology 101 test , he has concluded that he ’ s going to fail the entire course and probably flunk out of college altogether . These errors in thinking have contributed to Ray ’ s feelings of distress . His therapist will help him challenge these irrational beliefs , focus on their illogical basis , and correct them with more logical and rational thoughts and beliefs .", "hl_sentences": "Cognitive therapy is a form of psychotherapy that focuses on how a person ’ s thoughts lead to feelings of distress . The idea behind cognitive therapy is that how you think determines how you feel and act .", "question": { "cloze_format": "The idea behind ________ is that how you think determines how you feel and act.", "normal_format": "How you think determines how you feel and act. Is the idea behind what?", "question_choices": [ "cognitive therapy", "cognitive-behavioral therapy", "behavior therapy", "client-centered therapy" ], "question_id": "fs-idm128445200", "question_text": "The idea behind ________ is that how you think determines how you feel and act." }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 2, "ans_text": "bipolar disorder" }, "bloom": null, "hl_context": "<hl> Lithium , Depakote , Lamictal , Tegretol <hl> Different types and classes of medications are prescribed for different disorders . <hl> A depressed person might be given an antidepressant , a bipolar individual might be given a mood stabilizer , and a schizophrenic individual might be given an antipsychotic . <hl> <hl> These medications treat the symptoms of a psychological disorder . <hl> They can help people feel better so that they can function on a daily basis , but they do not cure the disorder . Some people may only need to take a psychotropic medication for a short period of time . Others with severe disorders like bipolar disorder or schizophrenia may need to take psychotropic medication for a long time . Table 16.2 shows the types of medication and how they are used .", "hl_sentences": "Lithium , Depakote , Lamictal , Tegretol A depressed person might be given an antidepressant , a bipolar individual might be given a mood stabilizer , and a schizophrenic individual might be given an antipsychotic . These medications treat the symptoms of a psychological disorder .", "question": { "cloze_format": "Mood stabilizers, such as lithium, are used to treat ________.", "normal_format": "What are mood stabilizers, such as lithium, used to treat?", "question_choices": [ "anxiety disorders", "depression", "bipolar disorder", "ADHD" ], "question_id": "fs-idm113610720", "question_text": "Mood stabilizers, such as lithium, are used to treat ________." }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 2, "ans_text": "group therapy" }, "bloom": null, "hl_context": "<hl> In group therapy , a clinician meets together with several clients with similar problems ( Figure 16.16 ) . <hl> When children are placed in group therapy , it is particularly important to match clients for age and problems . One benefit of group therapy is that it can help decrease a client ’ s shame and isolation about a problem while offering needed support , both from the therapist and other members of the group ( American Psychological Association , 2014 ) . A nine-year-old sexual abuse victim , for example , may feel very embarrassed and ashamed . If he is placed in a group with other sexually abused boys , he will realize that he is not alone . A child struggling with poor social skills would likely benefit from a group with a specific curriculum to foster special skills . A woman suffering from post-partum depression could feel less guilty and more supported by being in a group with similar women .", "hl_sentences": "In group therapy , a clinician meets together with several clients with similar problems ( Figure 16.16 ) .", "question": { "cloze_format": "A treatment modality in which 5–10 people with the same issue or concern meet together with a trained clinician is known as ________.", "normal_format": "What is a treatment modality in which 5–10 people with the same issue or concern meet together with a trained clinician known as?", "question_choices": [ "family therapy", "couples therapy", "group therapy", "self-help group" ], "question_id": "fs-idm161631280", "question_text": "A treatment modality in which 5–10 people with the same issue or concern meet together with a trained clinician is known as ________." }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 0, "ans_text": "The therapist gathers specific information to address the client’s immediate needs such as the presenting problem, the client’s support system, and insurance status. The therapist informs the client about confidentiality, fees, and what to expect in a therapy session." }, "bloom": "2", "hl_context": "Once a person seeks treatment , whether voluntarily or involuntarily , he has an intake done to assess his clinical needs . <hl> An intake is the therapist ’ s first meeting with the client . <hl> <hl> The therapist gathers specific information to address the client ’ s immediate needs , such as the presenting problem , the client ’ s support system , and insurance status . <hl> <hl> The therapist informs the client about confidentiality , fees , and what to expect in treatment . <hl> Confidentiality means the therapist cannot disclose confidential communications to any third party unless mandated or permitted by law to do so . During the intake , the therapist and client will work together to discuss treatment goals . Then a treatment plan will be formulated , usually with specific measurable objectives . Also , the therapist and client will discuss how treatment success will be measured and the estimated length of treatment . There are several different modalities of treatment ( Figure 16.14 ): Individual therapy , family therapy , couples therapy , and group therapy are the most common .", "hl_sentences": "An intake is the therapist ’ s first meeting with the client . The therapist gathers specific information to address the client ’ s immediate needs , such as the presenting problem , the client ’ s support system , and insurance status . The therapist informs the client about confidentiality , fees , and what to expect in treatment .", "question": { "cloze_format": "The following happens during an intake: ____.", "normal_format": "What happens during an intake?", "question_choices": [ "The therapist gathers specific information to address the client’s immediate needs such as the presenting problem, the client’s support system, and insurance status. The therapist informs the client about confidentiality, fees, and what to expect in a therapy session.", "The therapist guides what happens in the therapy session and designs a detailed approach to resolving each member’s presenting problem.", "The therapist meets with a couple to help them see how their individual backgrounds, beliefs, and actions are affecting their relationship.", "The therapist examines and discusses with the family the boundaries and structure of the family: For example, who makes the rules, who sleeps in the bed with whom, and how decisions are made." ], "question_id": "fs-idm109208208", "question_text": "What happens during an intake?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 0, "ans_text": "3 months" }, "bloom": null, "hl_context": "Specific factors make substance-related treatment much more effective . One factor is duration of treatment . <hl> Generally , a person with addict needs to be in treatment for at least three months to achieve a positive outcome ( Simpson , 1981 ; Simpson , Joe , & Bracy , 1982 ; NIDA , 2012 ) . <hl> This is due to the psychological , physiological , behavioral , and social aspects of abuse ( Simpson , 1981 ; Simpson et al . , 1982 ; NIDA , 2012 ) . While in treatment , a person with addiction might receive behavior therapy , which can help motivate the person with addiction to participate in the treatment program and teach strategies for dealing with cravings and how to prevent relapse . Also , treatment needs to be holistic and address multiple needs , not just the drug addiction . This means that treatment will address factors such as communication , stress management , relationship issues , parenting , vocational concerns , and legal concerns ( McGovern & Carroll , 2003 ; NIDA , 2012 ) . While individual therapy is used in the treatment of substance-related disorders , group therapy is the most widespread treatment modality ( Weiss , Jaffee , de Menil , & Cogley , 2004 ) . The rationale behind using group therapy for addiction treatment is that people with addiction are much more likely to maintain sobriety in a group format . It has been suggested that this is due to the rewarding and therapeutic benefits of the group , such as support , affiliation , identification , and even confrontation ( Center for Substance Abuse Treatment , 2005 ) . For teenagers , the whole family often needs to participate in treatment to address issues such as family dynamics , communication , and relapse prevention . Family involvement in teen drug addiction is vital . Research suggests that greater parental involvement is correlated with a greater reduction in use by teen substance abusers . Also , mothers who participated in treatment displayed better mental health and greater warmth toward their children ( Bertrand et al . , 2013 ) . However , neither individual nor group therapy has been found to be more effective ( Weiss et al . , 2004 ) . Regardless of the type of treatment service , the primary focus is on abstinence or at the very least a significant reduction in use ( McGovern & Carroll , 2003 ) . Treatment also usually involves medications to detox a person with addiction safely after an overdose , to prevent seizures and agitation that often occur in detox , to prevent reuse of the drug , and to manage withdrawal symptoms . Getting off drugs often involves the use of drugs — some of which can be just as addictive . Detox can be difficult and dangerous . Link to Learning", "hl_sentences": "Generally , a person with addict needs to be in treatment for at least three months to achieve a positive outcome ( Simpson , 1981 ; Simpson , Joe , & Bracy , 1982 ; NIDA , 2012 ) .", "question": { "cloze_format": "The minimum amount of time addicts should receive treatment is ___ if they are to achieve a desired outcome.", "normal_format": "What is the minimum amount of time addicts should receive treatment if they are to achieve a desired outcome?", "question_choices": [ "3 months", "6 months", "9 months", "12 months" ], "question_id": "fs-idm135992096", "question_text": "What is the minimum amount of time addicts should receive treatment if they are to achieve a desired outcome?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 1, "ans_text": "comorbid disorder" }, "bloom": null, "hl_context": "Frequently , a person with an addiction to drugs and / or alcohol has an additional psychological disorder . <hl> Saying a person has comorbid disorders means the individual has two or more diagnoses . <hl> <hl> This can often be a substance-related diagnosis and another psychiatric diagnosis , such as depression , bipolar disorder , or schizophrenia . <hl> These individuals fall into the category of mentally ill and chemically addicted ( MICA ) — their problems are often chronic and expensive to treat , with limited success . Compared with the overall population , substance abusers are twice as likely to have a mood or anxiety disorder . Drug abuse can cause symptoms of mood and anxiety disorders and the reverse is also true — people with debilitating symptoms of a psychiatric disorder may self-medicate and abuse substances . In cases of comorbidity , the best treatment is thought to address both ( or multiple ) disorders simultaneously ( NIDA , 2012 ) . Behavior therapies are used to treat comorbid conditions , and in many cases , psychotropic medications are used along with psychotherapy . For example , evidence suggests that bupropion ( trade names : Wellbutrin and Zyban ) , approved for treating depression and nicotine dependence , might also help reduce craving and use of the drug methamphetamine ( NIDA , 2011 ) . However , more research is needed to better understand how these medications work — particularly when combined in patients with comorbidities . 16.5 The Sociocultural Model and Therapy Utilization Learning Objectives By the end of this section , you will be able to :", "hl_sentences": "Saying a person has comorbid disorders means the individual has two or more diagnoses . This can often be a substance-related diagnosis and another psychiatric diagnosis , such as depression , bipolar disorder , or schizophrenia .", "question": { "cloze_format": "When an individual has two or more diagnoses, which often includes a substance-related diagnosis and another psychiatric diagnosis, this is known as ________.", "normal_format": "When an individual has two or more diagnoses, which often includes a substance-related diagnosis and another psychiatric diagnosis, this is known as which of the following?", "question_choices": [ "bipolar disorder", "comorbid disorder", "codependency", "bi-morbid disorder" ], "question_id": "fs-idm132593184", "question_text": "When an individual has two or more diagnoses, which often includes a substance-related diagnosis and another psychiatric diagnosis, this is known as ________." }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 3, "ans_text": "relapse" }, "bloom": null, "hl_context": "Specific factors make substance-related treatment much more effective . One factor is duration of treatment . Generally , a person with addict needs to be in treatment for at least three months to achieve a positive outcome ( Simpson , 1981 ; Simpson , Joe , & Bracy , 1982 ; NIDA , 2012 ) . This is due to the psychological , physiological , behavioral , and social aspects of abuse ( Simpson , 1981 ; Simpson et al . , 1982 ; NIDA , 2012 ) . While in treatment , a person with addiction might receive behavior therapy , which can help motivate the person with addiction to participate in the treatment program and teach strategies for dealing with cravings and how to prevent relapse . Also , treatment needs to be holistic and address multiple needs , not just the drug addiction . This means that treatment will address factors such as communication , stress management , relationship issues , parenting , vocational concerns , and legal concerns ( McGovern & Carroll , 2003 ; NIDA , 2012 ) . While individual therapy is used in the treatment of substance-related disorders , group therapy is the most widespread treatment modality ( Weiss , Jaffee , de Menil , & Cogley , 2004 ) . The rationale behind using group therapy for addiction treatment is that people with addiction are much more likely to maintain sobriety in a group format . It has been suggested that this is due to the rewarding and therapeutic benefits of the group , such as support , affiliation , identification , and even confrontation ( Center for Substance Abuse Treatment , 2005 ) . <hl> For teenagers , the whole family often needs to participate in treatment to address issues such as family dynamics , communication , and relapse prevention . <hl> Family involvement in teen drug addiction is vital . Research suggests that greater parental involvement is correlated with a greater reduction in use by teen substance abusers . Also , mothers who participated in treatment displayed better mental health and greater warmth toward their children ( Bertrand et al . , 2013 ) . However , neither individual nor group therapy has been found to be more effective ( Weiss et al . , 2004 ) . Regardless of the type of treatment service , the primary focus is on abstinence or at the very least a significant reduction in use ( McGovern & Carroll , 2003 ) . <hl> Treatment also usually involves medications to detox a person with addiction safely after an overdose , to prevent seizures and agitation that often occur in detox , to prevent reuse of the drug , and to manage withdrawal symptoms . <hl> <hl> Getting off drugs often involves the use of drugs — some of which can be just as addictive . <hl> <hl> Detox can be difficult and dangerous . <hl> Link to Learning", "hl_sentences": "For teenagers , the whole family often needs to participate in treatment to address issues such as family dynamics , communication , and relapse prevention . Treatment also usually involves medications to detox a person with addiction safely after an overdose , to prevent seizures and agitation that often occur in detox , to prevent reuse of the drug , and to manage withdrawal symptoms . Getting off drugs often involves the use of drugs — some of which can be just as addictive . Detox can be difficult and dangerous .", "question": { "cloze_format": "John was drug-free for almost six months. Then he started hanging out with his addict friends, and he has now started abusing drugs again. This is an example of ________.", "normal_format": "John was drug-free for almost six months. Then he started hanging out with his addict friends, and he has now started abusing drugs again. What is this an example of?", "question_choices": [ "release", "reversion", "re-addiction", "relapse" ], "question_id": "fs-idm44869248", "question_text": "John was drug-free for almost six months. Then he started hanging out with his addict friends, and he has now started abusing drugs again. This is an example of ________." }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 2, "ans_text": "culture and background" }, "bloom": null, "hl_context": "<hl> The sociocultural perspective looks at you , your behaviors , and your symptoms in the context of your culture and background . <hl> For example , José is an 18 - year-old Hispanic male from a traditional family . José comes to treatment because of depression . During the intake session , he reveals that he is gay and is nervous about telling his family . He also discloses that he is concerned because his religious background has taught him that homosexuality is wrong . How does his religious and cultural background affect him ? How might his cultural background affect how his family reacts if José were to tell them he is gay ?", "hl_sentences": "The sociocultural perspective looks at you , your behaviors , and your symptoms in the context of your culture and background .", "question": { "cloze_format": "The sociocultural perspective looks at you, your behaviors, and your symptoms in the context of your ________.", "normal_format": "In which context, the sociocultural perspective looks at you, your behaviors, and your symptoms?", "question_choices": [ "education", "socioeconomic status", "culture and background", "age" ], "question_id": "fs-idp27071728", "question_text": "The sociocultural perspective looks at you, your behaviors, and your symptoms in the context of your ________." }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 3, "ans_text": "being a member of the ethnic majority" }, "bloom": "1", "hl_context": "Statistically , ethnic minorities tend to utilize mental health services less frequently than White , middle-class Americans ( Alegría et al . , 2008 ; Richman , Kohn-Wood , & Williams , 2007 ) . Why is this so ? Perhaps the reason has to do with access and availability of mental health services . Ethnic minorities and individuals of low socioeconomic status ( SES ) report that barriers to services include lack of insurance , transportation , and time ( Thomas & Snowden , 2002 ) . However , researchers have found that even when income levels and insurance variables are taken into account , ethnic minorities are far less likely to seek out and utilize mental health services . <hl> And when access to mental health services is comparable across ethnic and racial groups , differences in service utilization remain ( Richman et al . , 2007 ) . <hl>", "hl_sentences": "And when access to mental health services is comparable across ethnic and racial groups , differences in service utilization remain ( Richman et al . , 2007 ) .", "question": { "cloze_format": "___ is not listed as a barrier to mental health treatment.", "normal_format": "Which of the following was not listed as a barrier to mental health treatment?", "question_choices": [ "fears about treatment", "language", "transportation", "being a member of the ethnic majority" ], "question_id": "fs-idm127432976", "question_text": "Which of the following was not listed as a barrier to mental health treatment?" }, "references_are_paraphrase": 0 } ]
16
16.1 Mental Health Treatment: Past and Present Learning Objectives By the end of this section, you will be able to: Explain how people with psychological disorders have been treated throughout the ages Discuss deinstitutionalization Discuss the ways in which mental health services are delivered today Distinguish between voluntary and involuntary treatment Before we explore the various approaches to therapy used today, let’s begin our study of therapy by looking at how many people experience mental illness and how many receive treatment. According to the U.S. Department of Health and Human Services (2013), 19% of U.S. adults experienced mental illness in 2012. For teens (ages 13–18), the rate is similar to that of adults, and for children ages 8–15, current estimates suggest that 13% experience mental illness in a given year (National Institute of Mental Health [NIMH], n.d.-a) With many different treatment options available, approximately how many people receive mental health treatment per year? According to the Substance Abuse and Mental Health Services Administration (SAMHSA), in 2008, 13.4% of adults received treatment for a mental health issue (NIMH, n.d.-b). These percentages, shown in Figure 16.2 , reflect the number of adults who received care in inpatient and outpatient settings and/or used prescription medication for psychological disorders. Children and adolescents also receive mental health services. The Centers for Disease Control and Prevention's National Health and Nutrition Examination Survey (NHANES) found that approximately half (50.6%) of children with mental disorders had received treatment for their disorder within the past year (NIMH, n.d.-c). However, there were some differences between treatment rates by category of disorder ( Figure 16.3 ). For example, children with anxiety disorders were least likely to have received treatment in the past year, while children with ADHD or a conduct disorder were more likely to receive treatment. Can you think of some possible reasons for these differences in receiving treatment? Considering the many forms of treatment for mental health disorders available today, how did these forms of treatment emerge? Let’s take a look at the history of mental health treatment from the past (with some questionable approaches in light of modern understanding of mental illness) to where we are today. Treatment in the Past For much of history, the mentally ill have been treated very poorly. It was believed that mental illness was caused by demonic possession, witchcraft, or an angry god (Szasz, 1960). For example, in medieval times, abnormal behaviors were viewed as a sign that a person was possessed by demons. If someone was considered to be possessed, there were several forms of treatment to release spirits from the individual. The most common treatment was exorcism, often conducted by priests or other religious figures: Incantations and prayers were said over the person’s body, and she may have been given some medicinal drinks. Another form of treatment for extreme cases of mental illness was trephining: A small hole was made in the afflicted individual’s skull to release spirits from the body. Most people treated in this manner died. In addition to exorcism and trephining, other practices involved execution or imprisonment of people with psychological disorders. Still others were left to be homeless beggars. Generally speaking, most people who exhibited strange behaviors were greatly misunderstood and treated cruelly. The prevailing theory of psychopathology in earlier history was the idea that mental illness was the result of demonic possession by either an evil spirit or an evil god because early beliefs incorrectly attributed all unexplainable phenomena to deities deemed either good or evil. From the late 1400s to the late 1600s, a common belief perpetuated by some religious organizations was that some people made pacts with the devil and committed horrible acts, such as eating babies (Blumberg, 2007). These people were considered to be witches and were tried and condemned by courts—they were often burned at the stake. Worldwide, it is estimated that tens of thousands of mentally ill people were killed after being accused of being witches or under the influence of witchcraft (Hemphill, 1966) By the 18th century, people who were considered odd and unusual were placed in asylums ( Figure 16.4 ). Asylums were the first institutions created for the specific purpose of housing people with psychological disorders, but the focus was ostracizing them from society rather than treating their disorders. Often these people were kept in windowless dungeons, beaten, chained to their beds, and had little to no contact with caregivers. In the late 1700s, a French physician, Philippe Pinel , argued for more humane treatment of the mentally ill. He suggested that they be unchained and talked to, and that’s just what he did for patients at La Salpêtrière in Paris in 1795 ( Figure 16.5 ). Patients benefited from this more humane treatment, and many were able to leave the hospital. In the 19th century, Dorothea Dix led reform efforts for mental health care in the United States ( Figure 16.6 ). She investigated how those who are mentally ill and poor were cared for, and she discovered an underfunded and unregulated system that perpetuated abuse of this population (Tiffany, 1891). Horrified by her findings, Dix began lobbying various state legislatures and the U.S. Congress for change (Tiffany, 1891). Her efforts led to the creation of the first mental asylums in the United States. Despite reformers’ efforts, however, a typical asylum was filthy, offered very little treatment, and often kept people for decades. At Willard Psychiatric Center in upstate New York, for example, one treatment was to submerge patients in cold baths for long periods of time. Electroshock treatment was also used, and the way the treatment was administered often broke patients’ backs; in 1943, doctors at Willard administered 1,443 shock treatments (Willard Psychiatric Center, 2009). (Electroshock is now called electroconvulsive treatment, and the therapy is still used, but with safeguards and under anesthesia. A brief application of electric stimulus is used to produce a generalized seizure. Controversy continues over its effectiveness versus the side effects.) Many of the wards and rooms were so cold that a glass of water would be frozen by morning (Willard Psychiatric Center, 2009). Willard’s doors were not closed until 1995. Conditions like these remained commonplace until well into the 20th century. Starting in 1954 and gaining popularity in the 1960s, antipsychotic medications were introduced. These proved a tremendous help in controlling the symptoms of certain psychological disorders, such as psychosis. Psychosis was a common diagnosis of individuals in mental hospitals, and it was often evidenced by symptoms like hallucinations and delusions, indicating a loss of contact with reality. Then in 1963, Congress passed and John F. Kennedy signed the Mental Retardation Facilities and Community Mental Health Centers Construction Act, which provided federal support and funding for community mental health centers (National Institutes of Health, 2013). This legislation changed how mental health services were delivered in the United States. It started the process of deinstitutionalization , the closing of large asylums, by providing for people to stay in their communities and be treated locally. In 1955, there were 558,239 severely mentally ill patients institutionalized at public hospitals (Torrey, 1997). By 1994, by percentage of the population, there were 92% fewer hospitalized individuals (Torrey, 1997). Mental Health Treatment Today Today, there are community mental health centers across the nation. They are located in neighborhoods near the homes of clients, and they provide large numbers of people with mental health services of various kinds and for many kinds of problems. Unfortunately, part of what occurred with deinstitutionalization was that those released from institutions were supposed to go to newly created centers, but the system was not set up effectively. Centers were underfunded, staff was not trained to handle severe illnesses such as schizophrenia, there was high staff burnout, and no provision was made for the other services people needed, such as housing, food, and job training. Without these supports, those people released under deinstitutionalization often ended up homeless. Even today, a large portion of the homeless population is considered to be mentally ill ( Figure 16.7 ). Statistics show that 26% of homeless adults living in shelters experience mental illness (U.S. Department of Housing and Urban Development [HUD], 2011). Another group of the mentally ill population is involved in the corrections system. According to a 2006 special report by the Bureau of Justice Statistics (BJS), approximately 705,600 mentally ill adults were incarcerated in the state prison system, and another 78,800 were incarcerated in the federal prison system. A further 479,000 were in local jails. According to the study, “people with mental illnesses are overrepresented in probation and parole populations at estimated rates ranging from two to four times the general population” (Prins & Draper, 2009, p. 23). The Treatment Advocacy Center reported that the growing number of mentally ill inmates has placed a burden on the correctional system (Torrey et al., 2014). Today, instead of asylums, there are psychiatric hospitals run by state governments and local community hospitals focused on short-term care. In all types of hospitals, the emphasis is on short-term stays, with the average length of stay being less than two weeks and often only several days. This is partly due to the very high cost of psychiatric hospitalization, which can be about $800 to $1000 per night (Stensland, Watson, & Grazier, 2012). Therefore, insurance coverage often limits the length of time a person can be hospitalized for treatment. Usually individuals are hospitalized only if they are an imminent threat to themselves or others. Link to Learning View this timeline showing the history of mental institutions in the United States. Most people suffering from mental illnesses are not hospitalized. If someone is feeling very depressed, complains of hearing voices, or feels anxious all the time, he or she might seek psychological treatment. A friend, spouse, or parent might refer someone for treatment. The individual might go see his primary care physician first and then be referred to a mental health practitioner. Some people seek treatment because they are involved with the state’s child protective services—that is, their children have been removed from their care due to abuse or neglect. The parents might be referred to psychiatric or substance abuse facilities and the children would likely receive treatment for trauma. If the parents are interested in and capable of becoming better parents, the goal of treatment might be family reunification. For other children whose parents are unable to change—for example, the parent or parents who are heavily addicted to drugs and refuse to enter treatment—the goal of therapy might be to help the children adjust to foster care and/or adoption ( Figure 16.8 ). Some people seek therapy because the criminal justice system referred them or required them to go. For some individuals, for example, attending weekly counseling sessions might be a condition of parole. If an individual is mandated to attend therapy, she is seeking services involuntarily. Involuntary treatment refers to therapy that is not the individual’s choice. Other individuals might voluntarily seek treatment. Voluntary treatment means the person chooses to attend therapy to obtain relief from symptoms. Psychological treatment can occur in a variety of places. An individual might go to a community mental health center or a practitioner in private or community practice. A child might see a school counselor, school psychologist, or school social worker. An incarcerated person might receive group therapy in prison. There are many different types of treatment providers, and licensing requirements vary from state to state. Besides psychologists and psychiatrists, there are clinical social workers, marriage and family therapists, and trained religious personnel who also perform counseling and therapy. A range of funding sources pay for mental health treatment: health insurance, government, and private pay. In the past, even when people had health insurance, the coverage would not always pay for mental health services. This changed with the Mental Health Parity and Addiction Equity Act of 2008, which requires group health plans and insurers to make sure there is parity of mental health services (U.S. Department of Labor, n.d.). This means that co-pays, total number of visits, and deductibles for mental health and substance abuse treatment need to be equal to and cannot be more restrictive or harsher than those for physical illnesses and medical/surgical problems. Finding treatment sources is also not always easy: there may be limited options, especially in rural areas and low-income urban areas; waiting lists; poor quality of care available for indigent patients; and financial obstacles such as co-pays, deductibles, and time off from work. Over 85% of the l,669 federally designated mental health professional shortage areas are rural; often primary care physicians and law enforcement are the first-line mental health providers (Ivey, Scheffler, & Zazzali, 1998), although they do not have the specialized training of a mental health professional, who often would be better equipped to provide care. Availability, accessibility, and acceptability (the stigma attached to mental illness) are all problems in rural areas. Approximately two-thirds of those with symptoms receive no care at all (U.S. Department of Health and Human Services, 2005; Wagenfeld, Murray, Mohatt, & DeBruiynb, 1994). At the end of 2013, the U.S. Department of Agriculture announced an investment of $50 million to help improve access and treatment for mental health problems as part of the Obama administration’s effort to strengthen rural communities. 16.2 Types of Treatment Learning Objectives By the end of this section, you will be able to: Distinguish between psychotherapy and biomedical therapy Recognize various orientations to psychotherapy Discuss psychotropic medications and recognize which medications are used to treat specific psychological disorders One of the goals of therapy is to help a person stop repeating and reenacting destructive patterns and to start looking for better solutions to difficult situations. This goal is reflected in the following poem: Autobiography in Five Short Chapters by Portia Nelson (1993) Chapter One I walk down the street. There is a deep hole in the sidewalk. I fall in. I am lost. . . . I am helpless. It isn't my fault. It takes forever to find a way out. Chapter Two I walk down the same street. There is a deep hole in the sidewalk. I pretend I don't see it. I fall in again. I can't believe I am in this same place. But, it isn't my fault. It still takes a long time to get out. Chapter Three I walk down the same street. There is a deep hole in the sidewalk. I see it is there. I still fall in . . . it's a habit . . . but, my eyes are open. I know where I am. It is my fault. I get out immediately. Chapter Four I walk down the same street. There is a deep hole in the sidewalk. I walk around it. Chapter Five I walk down another street. Two types of therapy are psychotherapy and biomedical therapy. Both types of treatment help people with psychological disorders, such as depression, anxiety, and schizophrenia. Psychotherapy is a psychological treatment that employs various methods to help someone overcome personal problems, or to attain personal growth. In modern practice, it has evolved ino what is known as psychodynamic therapy, which will be discussed later. Biomedical therapy involves medication and/or medical procedures to treat psychological disorders. First, we will explore the various psychotherapeutic orientations outlined in Table 16.1 (many of these orientations were discussed in the Introduction chapter). Type Description Example Psychodynamic psychotherapy Talk therapy based on belief that the unconscious and childhood conflicts impact behavior Patient talks about his past Play therapy Psychoanalytical therapy wherein interaction with toys is used instead of talk; used in child therapy Patient (child) acts out family scenes with dolls Behavior therapy Principles of learning applied to change undesirable behaviors Patient learns to overcome fear of elevators through several stages of relaxation techniques Cognitive therapy Awareness of cognitive process helps patients eliminate thought patterns that lead to distress Patient learns not to overgeneralize failure based on single failure Cognitive-behavioral therapy Work to change cognitive distortions and self-defeating behaviors Patient learns to identify self-defeating behaviors to overcome an eating disorder Humanistic therapy Increase self-awareness and acceptance through focus on conscious thoughts Patient learns to articulate thoughts that keep her from achieving her goals Table 16.1 Various Psychotherapy Techniques Psychotherapy Techniques: Psychoanalysis Psychoanalysis was developed by Sigmund Freud and was the first form of psychotherapy. It was the dominant therapeutic technique in the early 20th century, but it has since waned significantly in popularity. Freud believed most of our psychological problems are the result of repressed impulses and trauma experienced in childhood, and he believed psychoanalysis would help uncover long-buried feelings. In a psychoanalyst’s office, you might see a patient lying on a couch speaking of dreams or childhood memories, and the therapist using various Freudian methods such as free association and dream analysis ( Figure 16.9 ). In free association , the patient relaxes and then says whatever comes to mind at the moment. However, Freud felt that the ego would at times try to block, or repress, unacceptable urges or painful conflicts during free association. Consequently, a patient would demonstrate resistance to recalling these thoughts or situations. In dream analysis , a therapist interprets the underlying meaning of dreams. Psychoanalysis is a therapy approach that typically takes years. Over the course of time, the patient reveals a great deal about himself to the therapist. Freud suggested that during this patient-therapist relationship, the patient comes to develop strong feelings for the therapist—maybe positive feelings, maybe negative feelings. Freud called this transference : the patient transfers all the positive or negative emotions associated with the patient’s other relationships to the psychoanalyst. For example, Crystal is seeing a psychoanalyst. During the years of therapy, she comes to see her therapist as a father figure. She transfers her feelings about her father onto her therapist, perhaps in an effort to gain the love and attention she did not receive from her own father. Today, Freud’s psychoanalytical perspective has been expanded upon by the developments of subsequent theories and methodologies: the psychodynamic perspective. This approach to therapy remains centered on the role of people’s internal drives and forces, but treatment is less intensive than Freud’s original model. Link to Learning View a brief video that presents an overview of psychoanalysis theory, research, and practice. Psychotherapy: Play Therapy Play therapy is often used with children since they are not likely to sit on a couch and recall their dreams or engage in traditional talk therapy. This technique uses a therapeutic process of play to “help clients prevent or resolve psychosocial difficulties and achieve optimal growth” (O’Connor, 2000, p. 7). The idea is that children play out their hopes, fantasies, and traumas while using dolls, stuffed animals, and sandbox figurines ( Figure 16.10 ). Play therapy can also be used to help a therapist make a diagnosis. The therapist observes how the child interacts with toys (e.g., dolls, animals, and home settings) in an effort to understand the roots of the child’s disturbed behavior. Play therapy can be nondirective or directive. In nondirective play therapy, children are encouraged to work through their problems by playing freely while the therapist observes (LeBlanc & Ritchie, 2001). In directive play therapy, the therapist provides more structure and guidance in the play session by suggesting topics, asking questions, and even playing with the child (Harter, 1977). Psychotherapy: Behavior Therapy In psychoanalysis , therapists help their patients look into their past to uncover repressed feelings. In behavior therapy , a therapist employs principles of learning to help clients change undesirable behaviors—rather than digging deeply into one’s unconscious. Therapists with this orientation believe that dysfunctional behaviors, like phobias and bedwetting, can be changed by teaching clients new, more constructive behaviors. Behavior therapy employs both classical and operant conditioning techniques to change behavior. One type of behavior therapy utilizes classical conditioning techniques. Therapists using these techniques believe that dysfunctional behaviors are conditioned responses. Applying the conditioning principles developed by Ivan Pavlov, these therapists seek to recondition their clients and thus change their behavior. Emmie is eight years old, and frequently wets her bed at night. She’s been invited to several sleepovers, but she won’t go because of her problem. Using a type of conditioning therapy, Emmie begins to sleep on a liquid-sensitive bed pad that is hooked to an alarm. When moisture touches the pad, it sets off the alarm, waking up Emmie. When this process is repeated enough times, Emmie develops an association between urinary relaxation and waking up, and this stops the bedwetting. Emmie has now gone three weeks without wetting her bed and is looking forward to her first sleepover this weekend. One commonly used classical conditioning therapeutic technique is counterconditioning : a client learns a new response to a stimulus that has previously elicited an undesirable behavior. Two counterconditioning techniques are aversive conditioning and exposure therapy. Aversive conditioning uses an unpleasant stimulus to stop an undesirable behavior. Therapists apply this technique to eliminate addictive behaviors, such as smoking, nail biting, and drinking. In aversion therapy, clients will typically engage in a specific behavior (such as nail biting) and at the same time are exposed to something unpleasant, such as a mild electric shock or a bad taste. After repeated associations between the unpleasant stimulus and the behavior, the client can learn to stop the unwanted behavior. Aversion therapy has been used effectively for years in the treatment of alcoholism (Davidson, 1974; Elkins, 1991; Streeton & Whelan, 2001). One common way this occurs is through a chemically based substance known as Antabuse. When a person takes Antabuse and then consumes alcohol, uncomfortable side effects result including nausea, vomiting, increased heart rate, heart palpitations, severe headache, and shortness of breath. Antabuse is repeatedly paired with alcohol until the client associates alcohol with unpleasant feelings, which decreases the client’s desire to consume alcohol. Antabuse creates a conditioned aversion to alcohol because it replaces the original pleasure response with an unpleasant one. In exposure therapy , a therapist seeks to treat clients’ fears or anxiety by presenting them with the object or situation that causes their problem, with the idea that they will eventually get used to it. This can be done via reality, imagination, or virtual reality. Exposure therapy was first reported in 1924 by Mary Cover Jones, who is considered the mother of behavior therapy. Jones worked with a boy named Peter who was afraid of rabbits. Her goal was to replace Peter’s fear of rabbits with a conditioned response of relaxation, which is a response that is incompatible with fear ( Figure 16.11 ). How did she do it? Jones began by placing a caged rabbit on the other side of a room with Peter while he ate his afternoon snack. Over the course of several days, Jones moved the rabbit closer and closer to where Peter was seated with his snack. After two months of being exposed to the rabbit while relaxing with his snack, Peter was able to hold the rabbit and pet it while eating (Jones, 1924). Thirty years later, Joseph Wolpe (1958) refined Jones’s techniques, giving us the behavior therapy technique of exposure therapy that is used today. A popular form of exposure therapy is systematic desensitization , wherein a calm and pleasant state is gradually associated with increasing levels of anxiety-inducing stimuli. The idea is that you can’t be nervous and relaxed at the same time. Therefore, if you can learn to relax when you are facing environmental stimuli that make you nervous or fearful, you can eventually eliminate your unwanted fear response (Wolpe, 1958) ( Figure 16.12 ). How does exposure therapy work? Jayden is terrified of elevators. Nothing bad has ever happened to him on an elevator, but he’s so afraid of elevators that he will always take the stairs. That wasn’t a problem when Jayden worked on the second floor of an office building, but now he has a new job—on the 29th floor of a skyscraper in downtown Los Angeles. Jayden knows he can’t climb 29 flights of stairs in order to get to work each day, so he decided to see a behavior therapist for help. The therapist asks Jayden to first construct a hierarchy of elevator-related situations that elicit fear and anxiety. They range from situations of mild anxiety such as being nervous around the other people in the elevator, to the fear of getting an arm caught in the door, to panic-provoking situations such as getting trapped or the cable snapping. Next, the therapist uses progressive relaxation. She teaches Jayden how to relax each of his muscle groups so that he achieves a drowsy, relaxed, and comfortable state of mind. Once he’s in this state, she asks Jayden to imagine a mildly anxiety-provoking situation. Jayden is standing in front of the elevator thinking about pressing the call button. If this scenario causes Jayden anxiety, he lifts his finger. The therapist would then tell Jayden to forget the scene and return to his relaxed state. She repeats this scenario over and over until Jayden can imagine himself pressing the call button without anxiety. Over time the therapist and Jayden use progressive relaxation and imagination to proceed through all of the situations on Jayden’s hierarchy until he becomes desensitized to each one. After this, Jayden and the therapist begin to practice what he only previously envisioned in therapy, gradually going from pressing the button to actually riding an elevator. The goal is that Jayden will soon be able to take the elevator all the way up to the 29th floor of his office without feeling any anxiety. Sometimes, it’s too impractical, expensive, or embarrassing to re-create anxiety- producing situations, so a therapist might employ virtual reality exposure therapy by using a simulation to help conquer fears. Virtual reality exposure therapy has been used effectively to treat numerous anxiety disorders such as the fear of public speaking, claustrophobia (fear of enclosed spaces), aviophobia (fear of flying), and post-traumatic stress disorder (PTSD), a trauma and stressor-related disorder (Gerardi, Cukor, Difede, Rizzo, & Rothbaum, 2010). Link to Learning A new virtual reality exposure therapy is being used to treat PTSD in soldiers. Virtual Iraq is a simulation that mimics Middle Eastern cities and desert roads with situations similar to those soldiers experienced while deployed in Iraq. This method of virtual reality exposure therapy has been effective in treating PTSD for combat veterans. Approximately 80% of participants who completed treatment saw clinically significant reduction in their symptoms of PTSD, anxiety, and depression (Rizzo et al., 2010). Watch this Virtual Iraq video showing soldiers being treated via simulation. Some behavior therapies employ operant conditioning. Recall what you learned about operant conditioning: We have a tendency to repeat behaviors that are reinforced. What happens to behaviors that are not reinforced? They become extinguished. These principles can be applied to help people with a wide range of psychological problems. For instance, operant conditioning techniques designed to reinforce positive behaviors and punish unwanted behaviors have been an effective tool to help children with autism (Lovaas, 1987, 2003; Sallows & Graupner, 2005; Wolf & Risley, 1967). This technique is called Applied Behavior Analysis (ABA). In this treatment, child-specific reinforcers (e.g., stickers, praise, candy, bubbles, and extra play time) are used to reward and motivate autistic children when they demonstrate desired behaviors such as sitting on a chair when requested, verbalizing a greeting, or making eye contact. Punishment such as a timeout or a sharp “No!” from the therapist or parent might be used to discourage undesirable behaviors such as pinching, scratching, and pulling hair. One popular operant conditioning intervention is called the token economy . This involves a controlled setting where individuals are reinforced for desirable behaviors with tokens, such as a poker chip, that can be exchanged for items or privileges. Token economies are often used in psychiatric hospitals to increase patient cooperation and activity levels. Patients are rewarded with tokens when they engage in positive behaviors (e.g., making their beds, brushing their teeth, coming to the cafeteria on time, and socializing with other patients). They can later exchange the tokens for extra TV time, private rooms, visits to the canteen, and so on (Dickerson, Tenhula, & Green-Paden, 2005). Psychotherapy: Cognitive Therapy Cognitive therapy is a form of psychotherapy that focuses on how a person’s thoughts lead to feelings of distress. The idea behind cognitive therapy is that how you think determines how you feel and act. Cognitive therapists help their clients change dysfunctional thoughts in order to relieve distress. They help a client see how they misinterpret a situation (cognitive distortion). For example, a client may overgeneralize. Because Ray failed one test in his Psychology 101 course, he feels he is stupid and worthless. These thoughts then cause his mood to worsen. Therapists also help clients recognize when they blow things out of proportion. Because Ray failed his Psychology 101 test, he has concluded that he’s going to fail the entire course and probably flunk out of college altogether. These errors in thinking have contributed to Ray’s feelings of distress. His therapist will help him challenge these irrational beliefs, focus on their illogical basis, and correct them with more logical and rational thoughts and beliefs. Cognitive therapy was developed by psychiatrist Aaron Beck in the 1960s. His initial focus was on depression and how a client’s self-defeating attitude served to maintain a depression despite positive factors in her life (Beck, Rush, Shaw, & Emery, 1979) ( Figure 16.13 ). Through questioning, a cognitive therapist can help a client recognize dysfunctional ideas, challenge catastrophizing thoughts about themselves and their situations, and find a more positive way to view things (Beck, 2011). Link to Learning View a brief video in which Judith Beck talks about cognitive therapy and conducts a session with a client. Psychotherapy: Cognitive-Behavioral Therapy Cognitive-behavioral therapists focus much more on present issues than on a patient’s childhood or past, as in other forms of psychotherapy. One of the first forms of cognitive-behavioral therapy was rational emotive therapy (RET) , which was founded by Albert Ellis and grew out of his dislike of Freudian psychoanalysis (Daniel, n.d.). Behaviorists such as Joseph Wolpe also influenced Ellis’s therapeutic approach (National Association of Cognitive-Behavioral Therapists, 2009). Cognitive-behavioral therapy (CBT) helps clients examine how their thoughts affect their behavior. It aims to change cognitive distortions and self-defeating behaviors. In essence, this approach is designed to change the way people think as well as how they act. It is similar to cognitive therapy in that CBT attempts to make individuals aware of their irrational and negative thoughts and helps people replace them with new, more positive ways of thinking. It is also similar to behavior therapies in that CBT teaches people how to practice and engage in more positive and healthy approaches to daily situations. In total, hundreds of studies have shown the effectiveness of cognitive-behavioral therapy in the treatment of numerous psychological disorders such as depression, PTSD, anxiety disorders, eating disorders, bipolar disorder, and substance abuse (Beck Institute for Cognitive Behavior Therapy, n.d.). For example, CBT has been found to be effective in decreasing levels of hopelessness and suicidal thoughts in previously suicidal teenagers (Alavi, Sharifi, Ghanizadeh, & Dehbozorgi, 2013). Cognitive-behavioral therapy has also been effective in reducing PTSD in specific populations, such as transit workers (Lowinger & Rombom, 2012). Cognitive-behavioral therapy aims to change cognitive distortions and self-defeating behaviors using techniques like the ABC model. With this model, there is an A ction (sometimes called an activating event), the B elief about the event, and the C onsequences of this belief. Let’s say, Jon and Joe both go to a party. Jon and Joe each have met a young woman at the party: Jon is talking with Megan most of the party, and Joe is talking with Amanda. At the end of the party, Jon asks Megan for her phone number and Joe asks Amanda. Megan tells Jon she would rather not give him her number, and Amanda tells Joe the same thing. Both Jon and Joe are surprised, as they thought things were going well. What can Jon and Joe tell themselves about why the women were not interested? Let’s say Jon tells himself he is a loser, or is ugly, or “has no game.” Jon then gets depressed and decides not to go to another party, which starts a cycle that keeps him depressed. Joe tells himself that he had bad breath, goes out and buys a new toothbrush, goes to another party, and meets someone new. Jon’s belief about what happened results in a consequence of further depression, whereas Joe’s belief does not. Jon is internalizing the attribution or reason for the rebuffs, which triggers his depression. On the other hand, Joe is externalizing the cause, so his thinking does not contribute to feelings of depression. Cognitive-behavioral therapy examines specific maladaptive and automatic thoughts and cognitive distortions. Some examples of cognitive distortions are all-or-nothing thinking, overgeneralization, and jumping to conclusions. In overgeneralization, someone takes a small situation and makes it huge—for example, instead of saying, “This particular woman was not interested in me,” the man says, “I am ugly, a loser, and no one is ever going to be interested in me.” All or nothing thinking, which is a common type of cognitive distortion for people suffering from depression, reflects extremes. In other words, everything is black or white. After being turned down for a date, Jon begins to think, “No woman will ever go out with me. I’m going to be alone forever.” He begins to feel anxious and sad as he contemplates his future. The third kind of distortion involves jumping to conclusions—assuming that people are thinking negatively about you or reacting negatively to you, even though there is no evidence. Consider the example of Savannah and Hillaire, who recently met at a party. They have a lot in common, and Savannah thinks they could become friends. She calls Hillaire to invite her for coffee. Since Hillaire doesn’t answer, Savannah leaves her a message. Several days go by and Savannah never hears back from her potential new friend. Maybe Hillaire never received the message because she lost her phone or she is too busy to return the phone call. But if Savannah believes that Hillaire didn’t like Savannah or didn’t want to be her friend, she is demonstrating the cognitive distortion of jumping to conclusions. How effective is CBT? One client said this about his cognitive-behavioral therapy: I have had many painful episodes of depression in my life, and this has had a negative effect on my career and has put considerable strain on my friends and family. The treatments I have received, such as taking antidepressants and psychodynamic counseling, have helped [me] to cope with the symptoms and to get some insights into the roots of my problems. CBT has been by far the most useful approach I have found in tackling these mood problems. It has raised my awareness of how my thoughts impact on my moods. How the way I think about myself, about others and about the world can lead me into depression. It is a practical approach, which does not dwell so much on childhood experiences, whilst acknowledging that it was then that these patterns were learned. It looks at what is happening now, and gives tools to manage these moods on a daily basis. (Martin, 2007, n.p.) Psychotherapy: Humanistic Therapy Humanistic psychology focuses on helping people achieve their potential. So it makes sense that the goal of humanistic therapy is to help people become more self-aware and accepting of themselves. In contrast to psychoanalysis, humanistic therapists focus on conscious rather than unconscious thoughts. They also emphasize the patient’s present and future, as opposed to exploring the patient’s past. Psychologist Carl Rogers developed a therapeutic orientation known as Rogerian , or client-centered therapy . Note the change from patients to clients . Rogers (1951) felt that the term patient suggested the person seeking help was sick and looking for a cure. Since this is a form of nondirective therapy , a therapeutic approach in which the therapist does not give advice or provide interpretations but helps the person to identify conflicts and understand feelings, Rogers (1951) emphasized the importance of the person taking control of his own life to overcome life’s challenges. In client-centered therapy, the therapist uses the technique of active listening. In active listening, the therapist acknowledges, restates, and clarifies what the client expresses. Therapists also practice what Rogers called unconditional positive regard , which involves not judging clients and simply accepting them for who they are. Rogers (1951) also felt that therapists should demonstrate genuineness, empathy, and acceptance toward their clients because this helps people become more accepting of themselves, which results in personal growth. Evaluating Various Forms of Psychotherapy How can we assess the effectiveness of psychotherapy? Is one technique more effective than another? For anyone considering therapy, these are important questions. According to the American Psychological Association, three factors work together to produce successful treatment. The first is the use of evidence-based treatment that is deemed appropriate for your particular issue. The second important factor is the clinical expertise of the psychologist or therapist. The third factor is your own characteristics, values, preferences, and culture. Many people begin psychotherapy feeling like their problem will never be resolved; however, psychotherapy helps people see that they can do things to make their situation better. Psychotherapy can help reduce a person’s anxiety, depression, and maladaptive behaviors. Through psychotherapy, individuals can learn to engage in healthy behaviors designed to help them better express emotions, improve relationships, think more positively, and perform more effectively at work or school. Many studies have explored the effectiveness of psychotherapy. For example, one large-scale study that examined 16 meta-analyses of CBT reported that it was equally effective or more effective than other therapies in treating PTSD, generalized anxiety disorder, depression, and social phobia (Butlera, Chapmanb, Formanc, & Becka, 2006). Another study found that CBT was as effective at treating depression (43% success rate) as prescription medication (50% success rate) compared to the placebo rate of 25% (DeRubeis et al., 2005). Another meta-analysis found that psychodynamic therapy was also as effective at treating these types of psychological issues as CBT (Shedler, 2010). However, no studies have found one psychotherapeutic approach more effective than another (Abbass, Kisely, & Kroenke, 2006; Chorpita et al., 2011), nor have they shown any relationship between a client’s treatment outcome and the level of the clinician’s training or experience (Wampold, 2007). Regardless of which type of psychotherapy an individual chooses, one critical factor that determines the success of treatment is the person’s relationship with the psychologist or therapist. Biomedical Therapies Individuals can be prescribed biologically based treatments or psychotropic medications that are used to treat mental disorders. While these are often used in combination with psychotherapy, they also are taken by individuals not in therapy. This is known as biomedical therapy . Medications used to treat psychological disorders are called psychotropic medications and are prescribed by medical doctors, including psychiatrists. In Louisiana and New Mexico, psychologists are able to prescribe some types of these medications (American Psychological Association, 2014). Different types and classes of medications are prescribed for different disorders. A depressed person might be given an antidepressant, a bipolar individual might be given a mood stabilizer, and a schizophrenic individual might be given an antipsychotic. These medications treat the symptoms of a psychological disorder. They can help people feel better so that they can function on a daily basis, but they do not cure the disorder. Some people may only need to take a psychotropic medication for a short period of time. Others with severe disorders like bipolar disorder or schizophrenia may need to take psychotropic medication for a long time. Table 16.2 shows the types of medication and how they are used. Type of Medication Used to Treat Brand Names of Commonly Prescribed Medications How They Work Side Effects Antipsychotics (developed in the 1950s) Schizophrenia and other types of severe thought disorders Haldol, Mellaril, Prolixin, Thorazine Treat positive psychotic symptoms such as auditory and visual hallucinations, delusions, and paranoia by blocking the neurotransmitter dopamine Long-term use can lead to tardive dyskinesia, involuntary movements of the arms, legs, tongue and facial muscles, resulting in Parkinson’s-like tremors Atypical Antipsychotics (developed in the late 1980s) Schizophrenia and other types of severe thought disorders Abilify, Risperdal, Clozaril Treat the negative symptoms of schizophrenia, such as withdrawal and apathy, by targeting both dopamine and serotonin receptors; newer medications may treat both positive and negative symptoms Can increase the risk of obesity and diabetes as well as elevate cholesterol levels; constipation, dry mouth, blurred vision, drowsiness, and dizziness Anti-depressants Depression and increasingly for anxiety Paxil, Prozac, Zoloft (selective serotonin reuptake inhibitors, [SSRIs]); Tofranil and Elavil (tricyclics) Alter levels of neurotransmitters such as serotonin and norepinephrine SSRIs: headache, nausea, weight gain, drowsiness, reduced sex drive Tricyclics: dry mouth, constipation, blurred vision, drowsiness, reduced sex drive, increased risk of suicide Anti-anxiety agents Anxiety and agitation that occur in OCD, PTSD, panic disorder, and social phobia Xanax, Valium, Ativan Depress central nervous system activity Drowsiness, dizziness, headache, fatigue, lightheadedness Mood Stabilizers Bipolar disorder Lithium, Depakote, Lamictal, Tegretol Treat episodes of mania as well as depression Excessive thirst, irregular heartbeat, itching/rash, swelling (face, mouth, and extremities), nausea, loss of appetite Stimulants ADHD Adderall, Ritalin Improve ability to focus on a task and maintain attention Decreased appetite, difficulty sleeping, stomachache, headache Table 16.2 Commonly Prescribed Psychotropic Medications Another biologically based treatment that continues to be used, although infrequently, is electroconvulsive therapy (ECT) (formerly known by its unscientific name as electroshock therapy). It involves using an electrical current to induce seizures to help alleviate the effects of severe depression. The exact mechanism is unknown, although it does help alleviate symptoms for people with severe depression who have not responded to traditional drug therapy (Pagnin, de Queiroz, Pini, & Cassano, 2004). About 85% of people treated with ECT improve (Reti, n.d.). However, the memory loss associated with repeated administrations has led to it being implemented as a last resort (Donahue, 2000; Prudic, Peyser, & Sackeim, 2000). A more recent alternative is transcranial magnetic stimulation (TMS), a procedure approved by the FDA in 2008 that uses magnetic fields to stimulate nerve cells in the brain to improve depression symptoms; it is used when other treatments have not worked (Mayo Clinic, 2012). Dig Deeper Evidence-based Practice A buzzword in therapy today is evidence-based practice. However, it’s not a novel concept but one that has been used in medicine for at least two decades. Evidence-based practice is used to reduce errors in treatment selection by making clinical decisions based on research (Sackett & Rosenberg, 1995). In any case, evidence-based treatment is on the rise in the field of psychology. So what is it, and why does it matter? In an effort to determine which treatment methodologies are evidenced-based, professional organizations such as the American Psychological Association (APA) have recommended that specific psychological treatments be used to treat certain psychological disorders (Chambless & Ollendick, 2001). According to the APA (2005), “Evidence-based practice in psychology (EBPP) is the integration of the best available research with clinical expertise in the context of patient characteristics, culture, and preferences” (p. 1). The foundational idea behind evidence based treatment is that best practices are determined by research evidence that has been compiled by comparing various forms of treatment (Charman & Barkham, 2005). These treatments are then operationalized and placed in treatment manuals—trained therapists follow these manuals. The benefits are that evidence-based treatment can reduce variability between therapists to ensure that a specific approach is delivered with integrity (Charman & Barkham, 2005). Therefore, clients have a higher chance of receiving therapeutic interventions that are effective at treating their specific disorder. While EBPP is based on randomized control trials, critics of EBPP reject it stating that the results of trials cannot be applied to individuals and instead determinations regarding treatment should be based on a therapist’s judgment (Mullen & Streiner, 2004). 16.3 Treatment Modalities Learning Objectives By the end of this section, you will be able to: Distinguish between the various modalities of treatment Discuss benefits of group therapy Once a person seeks treatment, whether voluntarily or involuntarily, he has an intake done to assess his clinical needs. An intake is the therapist’s first meeting with the client. The therapist gathers specific information to address the client’s immediate needs, such as the presenting problem, the client’s support system, and insurance status. The therapist informs the client about confidentiality, fees, and what to expect in treatment. Confidentiality means the therapist cannot disclose confidential communications to any third party unless mandated or permitted by law to do so. During the intake, the therapist and client will work together to discuss treatment goals. Then a treatment plan will be formulated, usually with specific measurable objectives. Also, the therapist and client will discuss how treatment success will be measured and the estimated length of treatment. There are several different modalities of treatment ( Figure 16.14 ): Individual therapy, family therapy, couples therapy, and group therapy are the most common. Individual Therapy In individual therapy , also known as individual psychotherapy or individual counseling, the client and clinician meet one-on-one (usually from 45 minutes to 1 hour). These meetings typically occur weekly or every other week, and sessions are conducted in a confidential and caring environment ( Figure 16.15 ). The clinician will work with clients to help them explore their feelings, work through life challenges, identify aspects of themselves and their lives that they wish to change, and set goals to help them work towards these changes. A client might see a clinician for only a few sessions, or the client may attend individual therapy sessions for a year or longer. The amount of time spent in therapy depends on the needs of the client as well as her personal goals. Group Therapy In group therapy , a clinician meets together with several clients with similar problems ( Figure 16.16 ). When children are placed in group therapy, it is particularly important to match clients for age and problems. One benefit of group therapy is that it can help decrease a client’s shame and isolation about a problem while offering needed support, both from the therapist and other members of the group (American Psychological Association, 2014). A nine-year-old sexual abuse victim, for example, may feel very embarrassed and ashamed. If he is placed in a group with other sexually abused boys, he will realize that he is not alone. A child struggling with poor social skills would likely benefit from a group with a specific curriculum to foster special skills. A woman suffering from post-partum depression could feel less guilty and more supported by being in a group with similar women. Group therapy also has some specific limitations. Members of the group may be afraid to speak in front of other people because sharing secrets and problems with complete strangers can be stressful and overwhelming. There may be personality clashes and arguments among group members. There could also be concerns about confidentiality: Someone from the group might share what another participant said to people outside of the group. Another benefit of group therapy is that members can confront each other about their patterns. For those with some types of problems, such as sexual abusers, group therapy is the recommended treatment. Group treatment for this population is considered to have several benefits: Group treatment is more economical than individual, couples, or family therapy. Sexual abusers often feel more comfortable admitting and discussing their offenses in a treatment group where others are modeling openness. Clients often accept feedback about their behavior more willingly from other group members than from therapists. Finally, clients can practice social skills in group treatment settings. (McGrath, Cumming, Burchard, Zeoli, & Ellerby, 2009) Groups that have a strong educational component are called psycho-educational groups. For example, a group for children whose parents have cancer might discuss in depth what cancer is, types of treatment for cancer, and the side effects of treatments, such as hair loss. Often, group therapy sessions with children take place in school. They are led by a school counselor, a school psychologist, or a school social worker. Groups might focus on test anxiety, social isolation, self-esteem, bullying, or school failure (Shechtman, 2002). Whether the group is held in school or in a clinician’s office, group therapy has been found to be effective with children facing numerous kinds of challenges (Shechtman, 2002). During a group session, the entire group could reflect on an individual’s problem or difficulties, and others might disclose what they have done in that situation. When a clinician is facilitating a group, the focus is always on making sure that everyone benefits and participates in the group and that no one person is the focus of the entire session. Groups can be organized in various ways: some have an overarching theme or purpose, some are time-limited, some have open membership that allows people to come and go, and some are closed. Some groups are structured with planned activities and goals, while others are unstructured: There is no specific plan, and group members themselves decide how the group will spend its time and on what goals it will focus. This can become a complex and emotionally charged process, but it is also an opportunity for personal growth (Page & Berkow, 1994). Couples Therapy Couples therapy involves two people in an intimate relationship who are having difficulties and are trying to resolve them ( Figure 16.17 ). The couple may be dating, partnered, engaged, or married. The primary therapeutic orientation used in couples counseling is cognitive-behavioral therapy (Rathus & Sanderson, 1999). Couples meet with a therapist to discuss conflicts and/or aspects of their relationship that they want to change. The therapist helps them see how their individual backgrounds, beliefs, and actions are affecting their relationship. Often, a therapist tries to help the couple resolve these problems, as well as implement strategies that will lead to a healthier and happier relationship, such as how to listen, how to argue, and how to express feelings. However, sometimes, after working with a therapist, a couple will realize that they are too incompatible and will decide to separate. Some couples seek therapy to work out their problems, while others attend therapy to determine whether staying together is the best solution. Counseling couples in a high-conflict and volatile relationship can be difficult. In fact, psychologists Peter Pearson and Ellyn Bader, who founded the Couples Institute in Palo Alto, California, have compared the experience of the clinician in couples’ therapy to be like “piloting a helicopter in a hurricane” (Weil, 2012, para. 7). Family Therapy Family therapy is a special form of group therapy, consisting of one or more families. Although there are many theoretical orientations in family therapy, one of the most predominant is the systems approach. The family is viewed as an organized system, and each individual within the family is a contributing member who creates and maintains processes within the system that shape behavior (Minuchin, 1985). Each member of the family influences and is influenced by the others. The goal of this approach is to enhance the growth of each family member as well as that of the family as a whole. Often, dysfunctional patterns of communication that develop between family members can lead to conflict. A family with this dynamic might wish to attend therapy together rather than individually. In many cases, one member of the family has problems that detrimentally affect everyone. For example, a mother’s depression, teen daughter’s eating disorder, or father’s alcohol dependence could affect all members of the family. The therapist would work with all members of the family to help them cope with the issue, and to encourage resolution and growth in the case of the individual family member with the problem. With family therapy, the nuclear family (i.e., parents and children) or the nuclear family plus whoever lives in the household (e.g., grandparent) come into treatment. Family therapists work with the whole family unit to heal the family. There are several different types of family therapy. In structural family therapy , the therapist examines and discusses the boundaries and structure of the family: who makes the rules, who sleeps in the bed with whom, how decisions are made, and what are the boundaries within the family. In some families, the parents do not work together to make rules, or one parent may undermine the other, leading the children to act out. The therapist helps them resolve these issues and learn to communicate more effectively. Link to Learning Watch this video to view a structural family session. In strategic family therapy , the goal is to address specific problems within the family that can be dealt with in a relatively short amount of time. Typically, the therapist would guide what happens in the therapy session and design a detailed approach to resolving each member’s problem (Madanes, 1991). 16.4 Substance-Related and Addictive Disorders: A Special Case Learning Objectives By the end of this section, you will be able to: Recognize the goal of substance-related and addictive disorders treatment Discuss what makes for effective treatment Describe how comorbid disorders are treated Addiction is often viewed as a chronic disease ( Figure 16.18 ). The choice to use a substance is initially voluntary; however, because chronic substance use can permanently alter the neural structure in the prefrontal cortex, an area of the brain associated with decision-making and judgment, a person becomes driven to use drugs and/or alcohol (Muñoz-Cuevas, Athilingam, Piscopo, & Wilbrecht, 2013). This helps explain why relapse rates tend to be high. About 40%–60% of individuals relapse , which means they return to abusing drugs and/or alcohol after a period of improvement (National Institute on Drug Abuse [NIDA], 2008). The goal of substance-related treatment is to help a person with an addiction stop compulsive drug-seeking behaviors (NIDA, 2012). This means a person with addction will need long-term treatment, similar to a person battling a chronic physical disease such as hypertension or diabetes. Treatment usually includes behavioral therapy and/or medication, depending on the individual (NIDA, 2012). Specialized therapies have also been developed for specific types of substance-related disorders, including alcohol, cocaine, and opioids (McGovern & Carroll, 2003). Substance-related treatment is considered much more cost-effective than incarceration or not treating those with addictions (NIDA, 2012) ( Figure 16.19 ). What Makes Treatment Effective? Specific factors make substance-related treatment much more effective. One factor is duration of treatment. Generally, a person with addict needs to be in treatment for at least three months to achieve a positive outcome (Simpson, 1981; Simpson, Joe, & Bracy, 1982; NIDA, 2012). This is due to the psychological, physiological, behavioral, and social aspects of abuse (Simpson, 1981; Simpson et al., 1982; NIDA, 2012). While in treatment, a person with addiction might receive behavior therapy, which can help motivate the person with addiction to participate in the treatment program and teach strategies for dealing with cravings and how to prevent relapse. Also, treatment needs to be holistic and address multiple needs, not just the drug addiction. This means that treatment will address factors such as communication, stress management, relationship issues, parenting, vocational concerns, and legal concerns (McGovern & Carroll, 2003; NIDA, 2012). While individual therapy is used in the treatment of substance-related disorders, group therapy is the most widespread treatment modality (Weiss, Jaffee, de Menil, & Cogley, 2004). The rationale behind using group therapy for addiction treatment is that people with addiction are much more likely to maintain sobriety in a group format. It has been suggested that this is due to the rewarding and therapeutic benefits of the group, such as support, affiliation, identification, and even confrontation (Center for Substance Abuse Treatment, 2005). For teenagers, the whole family often needs to participate in treatment to address issues such as family dynamics, communication, and relapse prevention. Family involvement in teen drug addiction is vital. Research suggests that greater parental involvement is correlated with a greater reduction in use by teen substance abusers. Also, mothers who participated in treatment displayed better mental health and greater warmth toward their children (Bertrand et al., 2013). However, neither individual nor group therapy has been found to be more effective (Weiss et al., 2004). Regardless of the type of treatment service, the primary focus is on abstinence or at the very least a significant reduction in use (McGovern & Carroll, 2003). Treatment also usually involves medications to detox a person with addiction safely after an overdose, to prevent seizures and agitation that often occur in detox, to prevent reuse of the drug, and to manage withdrawal symptoms. Getting off drugs often involves the use of drugs—some of which can be just as addictive. Detox can be difficult and dangerous. Link to Learning Watch this video to find out more about treating substance-related disorders using the biological, behavioral, and psychodynamic approaches. Comorbid Disorders Frequently, a person with an addiction to drugs and/or alcohol has an additional psychological disorder. Saying a person has comorbid disorders means the individual has two or more diagnoses. This can often be a substance-related diagnosis and another psychiatric diagnosis, such as depression, bipolar disorder, or schizophrenia. These individuals fall into the category of mentally ill and chemically addicted (MICA)—their problems are often chronic and expensive to treat, with limited success. Compared with the overall population, substance abusers are twice as likely to have a mood or anxiety disorder. Drug abuse can cause symptoms of mood and anxiety disorders and the reverse is also true—people with debilitating symptoms of a psychiatric disorder may self-medicate and abuse substances. In cases of comorbidity , the best treatment is thought to address both (or multiple) disorders simultaneously (NIDA, 2012). Behavior therapies are used to treat comorbid conditions, and in many cases, psychotropic medications are used along with psychotherapy. For example, evidence suggests that bupropion (trade names: Wellbutrin and Zyban), approved for treating depression and nicotine dependence, might also help reduce craving and use of the drug methamphetamine (NIDA, 2011). However, more research is needed to better understand how these medications work—particularly when combined in patients with comorbidities. 16.5 The Sociocultural Model and Therapy Utilization Learning Objectives By the end of this section, you will be able to: Explain how the sociocultural model is used in therapy Discuss barriers to mental health services among ethnic minorities The sociocultural perspective looks at you, your behaviors, and your symptoms in the context of your culture and background. For example, José is an 18-year-old Hispanic male from a traditional family. José comes to treatment because of depression. During the intake session, he reveals that he is gay and is nervous about telling his family. He also discloses that he is concerned because his religious background has taught him that homosexuality is wrong. How does his religious and cultural background affect him? How might his cultural background affect how his family reacts if José were to tell them he is gay? As our society becomes increasingly multiethnic and multiracial, mental health professionals must develop cultural competence ( Figure 16.20 ), which means they must understand and address issues of race, culture, and ethnicity. They must also develop strategies to effectively address the needs of various populations for which Eurocentric therapies have limited application (Sue, 2004). For example, a counselor whose treatment focuses on individual decision making may be ineffective at helping a Chinese client with a collectivist approach to problem solving (Sue, 2004). Multicultural counseling and therapy aims to offer both a helping role and process that uses modalities and defines goals consistent with the life experiences and cultural values of clients. It strives to recognize client identities to include individual, group, and universal dimensions, advocate the use of universal and culture-specific strategies and roles in the healing process, and balancs the importance of individualism and collectivism in the assessment, diagnosis, and treatment of client and client systems (Sue, 2001). This therapeutic perspective integrates the impact of cultural and social norms, starting at the beginning of treatment. Therapists who use this perspective work with clients to obtain and integrate information about their cultural patterns into a unique treatment approach based on their particular situation (Stewart, Simmons, & Habibpour, 2012). Sociocultural therapy can include individual, group, family, and couples treatment modalities. Link to Learning Watch this short video to learn more about cultural competence and sociocultural treatments. Barriers to Treatment Statistically, ethnic minorities tend to utilize mental health services less frequently than White, middle-class Americans (Alegría et al., 2008; Richman, Kohn-Wood, & Williams, 2007). Why is this so? Perhaps the reason has to do with access and availability of mental health services. Ethnic minorities and individuals of low socioeconomic status (SES) report that barriers to services include lack of insurance, transportation, and time (Thomas & Snowden, 2002). However, researchers have found that even when income levels and insurance variables are taken into account, ethnic minorities are far less likely to seek out and utilize mental health services. And when access to mental health services is comparable across ethnic and racial groups, differences in service utilization remain (Richman et al., 2007). In a study involving thousands of women, it was found that the prevalence rate of anorexia was similar across different races, but that bulimia nervosa was more prevalent among Hispanic and African American women when compared with non-Hispanic whites (Marques et al., 2011). Although they have similar or higher rates of eating disorders, Hispanic and African American women with these disorders tend to seek and engage in treatment far less than Caucasian women. These findings suggest ethnic disparities in access to care, as well as clinical and referral practices that may prevent Hispanic and African American women from receiving care, which could include lack of bilingual treatment, stigma, fear of not being understood, family privacy, and lack of education about eating disorders. Perceptions and attitudes toward mental health services may also contribute to this imbalance. A recent study at King’s College, London, found many complex reasons why people do not seek treatment: self-sufficiency and not seeing the need for help, not seeing therapy as effective, concerns about confidentiality, and the many effects of stigma and shame (Clement et al., 2014). And in another study, African Americans exhibiting depression were less willing to seek treatment due to fear of possible psychiatric hospitalization as well as fear of the treatment itself (Sussman, Robins, & Earls, 1987). Instead of mental health treatment, many African Americans prefer to be self-reliant or use spiritual practices (Snowden, 2001; Belgrave & Allison, 2010). For example, it has been found that the Black church plays a significant role as an alternative to mental health services by providing prevention and treatment-type programs designed to enhance the psychological and physical well-being of its members (Blank, Mahmood, Fox, & Guterbock, 2002). Additionally, people belonging to ethnic groups that already report concerns about prejudice and discrimination are less likely to seek services for a mental illness because they view it as an additional stigma (Gary, 2005; Townes, Cunningham, & Chavez-Korell, 2009; Scott, McCoy, Munson, Snowden, & McMillen, 2011). For example, in one recent study of 462 older Korean Americans (over the age of 60) many participants reported suffering from depressive symptoms. However, 71% indicated they thought depression was a sign of personal weakness, and 14% reported that having a mentally ill family member would bring shame to the family (Jang, Chiriboga, & Okazaki, 2009). Language differences are a further barrier to treatment. In the previous study on Korean Americans’ attitudes toward mental health services, it was found that there were no Korean-speaking mental health professionals where the study was conducted (Orlando and Tampa, Florida) (Jang et al., 2009). Because of the growing number of people from ethnically diverse backgrounds, there is a need for therapists and psychologists to develop knowledge and skills to become culturally competent (Ahmed, Wilson, Henriksen, & Jones, 2011). Those providing therapy must approach the process from the context of the unique culture of each client (Sue & Sue, 2007). Dig Deeper Treatment Perceptions By the time a child is a senior in high school, 20% of his classmates—that is 1 in 5—will have experienced a mental health problem (U.S. Department of Health and Human Services, 1999), and 8%—about 1 in 12—will have attempted suicide (Centers for Disease Control and Prevention, 2014). Of those classmates experiencing mental disorders, only 20% will receive professional help (U.S. Public Health Service, 2000). Why? It seems that the public has a negative perception of children and teens with mental health disorders. According to researchers from Indiana University, the University of Virginia, and Columbia University, interviews with over 1,300 U.S. adults show that they believe children with depression are prone to violence and that if a child receives treatment for a psychological disorder, then that child is more likely to be rejected by peers at school. Bernice Pescosolido, author of the study, asserts that this is a misconception. However, stigmatization of psychological disorders is one of the main reasons why young people do not get the help they need when they are having difficulties. Pescosolido and her colleagues caution that this stigma surrounding mental illness, based on misconceptions rather than facts, can be devastating to the emotional and social well-being of our nation’s children. This warning played out as a national tragedy in the 2012 shootings at Sandy Hook Elementary. In her blog, Suzy DeYoung (2013), co-founder of Sandy Hook Promise (the organization parents and concerned others set up in the wake of the school massacre) speaks to treatment perceptions and what happens when children do not receive the mental health treatment they desperately need. I've become accustomed to the reaction when I tell people where I'm from. Eleven months later, it's as consistent as it was back in January. Just yesterday, inquiring as to the availability of a rental house this holiday season, the gentleman taking my information paused to ask, “Newtown, CT? Isn't that where that...that thing happened? A recent encounter in the Massachusetts Berkshires, however, took me by surprise. It was in a small, charming art gallery. The proprietor, a woman who looked to be in her 60s, asked where we were from. My response usually depends on my present mood and readiness for the inevitable dialogue. Sometimes it's simply, Connecticut. This time, I replied, Newtown, CT. The woman's demeanor abruptly shifted from one of amiable graciousness to one of visible agitation. “Oh my god,” she said wide eyed and open mouthed. “Did you know her?” . . . . “Her?” I inquired That woman,” she replied with disdain, “that woman that raised that monster.” “That woman's” name was Nancy Lanza. Her son, Adam, killed her with a rifle blast to the head before heading out to kill 20 children and six educators at Sandy Hook Elementary School in Newtown, CT last December 14th. When Nelba Marquez Greene, whose beautiful 6-year-old daughter, Ana, was killed by Adam Lanza, was recently asked how she felt about “that woman,” this was her reply: “She's a victim herself. And it's time in America that we start looking at mental illness with compassion, and helping people who need it. “This was a family that needed help, an individual that needed help and didn't get it. And what better can come of this, of this time in America, than if we can get help to people who really need it?” (pars. 1–7, 10–15) Fortunately, we are starting to see campaigns related to the destigmatization of mental illness and an increase in public education and awareness. Join the effort by encouraging and supporting those around you to seek help if they need it. To learn more, visit the National Alliance on Mental Illness (NAMI) website (http://www.nami.org/). The nation’s largest nonprofit mental health advocacy and support organization is NAMI.
u.s._history
Summary 21.1 The Origins of the Progressive Spirit in America In its first decade, the Progressive Era was a grassroots effort that ushered in reforms at state and local levels. At the beginning of the twentieth century, however, Progressive endeavors captured the attention of the federal government. The challenges of the late nineteenth century were manifold: fast-growing cities that were ill-equipped to house the working poor, hands-off politicians shackled into impotence by their system of political favors, and rural Americans struggling to keep their farms afloat. The muckraking journalists of the era published books and articles highlighting the social inequities of the day and extolling everyday Americans to help find solutions. Educated, middle-class, Anglo-Saxon Protestants dominated the movement, but Progressives were not a homogenous group: The movement counted African Americans, both women and men, and urban as well as rural dwellers among its ranks. Progressive causes ranged from anti-liquor campaigns to fair pay. Together, Progressives sought to advance the spread of democracy, improve efficiency in government and industry, and promote social justice. 21.2 Progressivism at the Grassroots Level Progressive campaigns stretched from the hurricane-ruined townships of Texas to the slums of New York, from the factory floor to the saloon door. But what tied together these disparate causes and groups was the belief that the country was in dire need of reform, and that answers were to be found within the activism and expertise of predominantly middle-class Americans on behalf of troubled communities. Some efforts, such as the National Child Labor Committee, pushed for federal legislation; however, most Progressive initiatives took place at the state and local levels, as Progressives sought to harness public support to place pressure on politicians. At the beginning of the twentieth century, a more radical, revolutionary breed of Progressivism began to evolve. While these radical Progressives generally shared the goals of their more mainstream counterparts, their strategies differed significantly. Mainstream Progressives and many middle-class Americans feared groups such as the Socialist Party of America and the Industrial Workers of the World, which emphasized workers’ empowerment and direct action. 21.3 New Voices for Women and African Americans The Progressive commitment to promoting democracy and social justice created an environment within which the movements for women’s and African American rights grew and flourished. Emergent leaders such as Elizabeth Cady Stanton, Susan B. Anthony, Carrie Chapman Catt, and Alice Paul spread the cause of woman suffrage, drawing in other activists and making the case for a constitutional amendment ensuring a woman’s right to vote. African Americans—guided by leaders such as Booker T. Washington and W. E. B. Du Bois—strove for civil rights and economic opportunity, although their philosophies and strategies differed significantly. In the women’s and civil rights movements alike, activists both advanced their own causes and paved the way for later efforts aimed at expanding equal opportunity and citizenship. 21.4 Progressivism in the White House Theodore Roosevelt became president only by historical accident, but his activism in the executive branch spoke to the Progressive spirit in the nation and transformed the president’s office for the twentieth century. The courage he displayed in his confrontation of big business and willingness to side with workers in capital-labor disputes, as well as his commitment to the preservation of federal lands, set an agenda his successors had to match. Like Roosevelt, William Howard Taft pushed antitrust rulings and expanded federal oversight of interstate commerce. But estrangement from his predecessor and mentor left Taft in a difficult position for reelection. Roosevelt’s third-party challenge as a Progressive split the Republican vote and handed Woodrow Wilson the presidency in 1912. A Progressive like his predecessors, Wilson was also a political creature who understood the need to do more in order to ensure his reelection. He, too, sought to limit the power of big businesses and stabilize the economy, and he ushered in a wave of Progressive legislation that grassroots Progressives had long called for. The nation’s entanglement in World War I, however, soon shunted the Progressive goals of democracy, efficiency, regulation, and social justice to the back burner. The nation’s new priorities included national security and making the world “safe for democracy.”
Chapter Outline 21.1 The Origins of the Progressive Spirit in America 21.2 Progressivism at the Grassroots Level 21.3 New Voices for Women and African Americans 21.4 Progressivism in the White House Introduction Women’s suffrage was one of many causes that emerged in the Progressive Era, as Americans confronted the numerous challenges of the late nineteenth century. Starting in the late 1800s, women increasingly were working outside the home—a task almost always done for money, not empowerment—as well as pursuing higher education, both at universities that were beginning to allow women to enroll and at female-only schools. Often, it was educated middle-class women with more time and resources that took up causes such as child labor and family health. As more women led new organizations or institutions, such as the settlement houses, they grew to have a greater voice on issues of social change. By the turn of the century, a strong movement had formed to advocate for a woman’s right to vote. For three decades, suffragist groups pushed for legislation to give women the right to vote in every state. As the illustration above shows ( Figure 21.1 ), the western states were the first to grant women the right to vote; it would not be until 1920 that the nation would extend that right to all women.
[ { "answer": { "ans_choice": 1, "ans_text": "B" }, "bloom": null, "hl_context": "Beginning in the second half of the nineteenth century , these Progressive journalists sought to expose critical social problems and exhort the public to take action . In his book , How the Other Half Lives ( 1890 ) , journalist and photographer Jacob Riis used photojournalism to capture the dismal and dangerous living conditions in working-class tenements in New York City ( Figure 21.3 ) . <hl> Ida Tarbell , perhaps the most well-known female muckraker , wrote a series of articles on the dangers of John D . Rockefeller ’ s powerful monopoly , Standard Oil . <hl> Her articles followed Henry Demarest Lloyd ’ s book , Wealth Against Commonwealth , published in 1894 , which examined the excesses of Standard Oil . Other writers , like Lincoln Steffens , explored corruption in city politics , or , like Ray Stannard Baker , researched unsafe working conditions and low pay in the coal mines .", "hl_sentences": "Ida Tarbell , perhaps the most well-known female muckraker , wrote a series of articles on the dangers of John D . Rockefeller ’ s powerful monopoly , Standard Oil .", "question": { "cloze_format": "Ida Tarbell wrote publicly about ___.", "normal_format": "What did Ida Tarbell publicly write about?", "question_choices": [ "the need for better housing in rural America", "the sinister business practices of Standard Oil", "the need for a national temperance movement", "the women’s suffrage cause in the American West" ], "question_id": "fs-idm6317264", "question_text": "Ida Tarbell wrote publicly about" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 0, "ans_text": "land reform" }, "bloom": null, "hl_context": "<hl> Progressive groups made tremendous strides on issues involving democracy , efficiency , and social justice . <hl> <hl> But they found that their grassroots approach was ill-equipped to push back against the most powerful beneficiaries of growing inequality , economic concentration , and corruption — big business . <hl> In their fight against the trusts , Progressives needed the leadership of the federal government , and they found it in Theodore Roosevelt in 1901 , through an accident of history . Muckrakers drew public attention to some of the most glaring inequities and scandals that grew out of the social ills of the Gilded Age and the hands-off approach of the federal government since the end of Reconstruction . These writers by and large addressed a White , middle-class and elite , native-born audience , even though Progressive movements and organizations involved a diverse range of Americans . What united these Progressives beyond their different backgrounds and causes was a set of uniting principles , however . Most strove for a perfection of democracy , which required the expansion of suffrage to worthy citizens and the restriction of political participation for those considered “ unfit ” on account of health , education , or race . <hl> Progressives also agreed that democracy had to be balanced with an emphasis on efficiency , a reliance on science and technology , and deference to the expertise of professionals . <hl> <hl> They repudiated party politics but looked to government to regulate the modern market economy . <hl> <hl> And they saw themselves as the agents of social justice and reform , as well as the stewards and guides of workers and the urban poor . <hl> Often , reformers ’ convictions and faith in their own expertise led them to dismiss the voices of the very people they sought to help .", "hl_sentences": "Progressive groups made tremendous strides on issues involving democracy , efficiency , and social justice . But they found that their grassroots approach was ill-equipped to push back against the most powerful beneficiaries of growing inequality , economic concentration , and corruption — big business . Progressives also agreed that democracy had to be balanced with an emphasis on efficiency , a reliance on science and technology , and deference to the expertise of professionals . They repudiated party politics but looked to government to regulate the modern market economy . And they saw themselves as the agents of social justice and reform , as well as the stewards and guides of workers and the urban poor .", "question": { "cloze_format": "____ was not a key area of focus for the Progressives.", "normal_format": "Which of the following was not a key area of focus for the Progressives?", "question_choices": [ "land reform", "democracy", "business regulation", "social justice" ], "question_id": "fs-idm22827856", "question_text": "Which of the following was not a key area of focus for the Progressives?" }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 2, "ans_text": "candidate selection by convention delegates" }, "bloom": null, "hl_context": "<hl> The first law involved the creation of the direct primary . <hl> <hl> Prior to this time , the only people who had a hand in selecting candidates for elections were delegates at conventions . <hl> <hl> Direct primaries allowed party members to vote directly for a candidate , with the nomination going to the one with the most votes . <hl> This was the beginning of the current system of holding a primary election before a general election . South Carolina adopted this system for statewide elections in 1896 ; in 1901 , Florida became the first state to use the direct primary in nominations for the presidency . It is the method currently used in three-quarters of U . S . states .", "hl_sentences": "The first law involved the creation of the direct primary . Prior to this time , the only people who had a hand in selecting candidates for elections were delegates at conventions . Direct primaries allowed party members to vote directly for a candidate , with the nomination going to the one with the most votes .", "question": { "cloze_format": "The direct primary replaced ____.", "normal_format": "What system did the direct primary replace?", "question_choices": [ "candidate selection by secret ballots", "candidate selection by machine bosses", "candidate selection by convention delegates", "an indirect primary" ], "question_id": "fs-idm62784336", "question_text": "What system did the direct primary replace?" }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 1, "ans_text": "B" }, "bloom": null, "hl_context": "What do you think about William Shepherd ’ s description ? What effect do you think it had on newspaper readers in the Midwest ? <hl> Another cause that garnered support from a key group of Progressives was the prohibition of liquor . <hl> <hl> This crusade , which gained followers through the Woman ’ s Christian Temperance Union ( WCTU ) and the Anti-Saloon League , directly linked Progressivism with morality and Christian reform initiatives , and saw in alcohol both a moral vice and a practical concern , as workingmen spent their wages on liquor and saloons , often turning violent towards each other or their families at home . <hl> The WCTU and Anti-Saloon League moved the efforts to eliminate the sale of alcohol from a bar-to-bar public opinion campaign to one of city-to-city and state-by-state votes ( Figure 21.9 ) . Through local option votes and subsequent statewide initiatives and referendums , the Anti-Saloon League succeeded in urging 40 percent of the nation ’ s counties to “ go dry ” by 1906 , and a full dozen states to do the same by 1909 . Their political pressure culminated in the passage of the Eighteenth Amendment to the U . S . Constitution , ratified in 1919 , which prohibited the manufacture , sale , and transportation of alcoholic beverages nationwide . <hl> Florence Kelley , a Progressive supporter of the NCLC , championed other social justice causes as well . <hl> <hl> As the first general secretary of the National Consumers League , which was founded in 1899 by Jane Addams and others , Kelley led one of the original battles to try and secure safety in factory working conditions . <hl> She particularly opposed sweatshop labor and urged the passage of an eight-hour-workday law in order to specifically protect women in the workplace . Kelley ’ s efforts were initially met with strong resistance from factory owners who exploited women ’ s labor and were unwilling to give up the long hours and low wages they paid in order to offer the cheapest possible product to consumers . But in 1911 , a tragedy turned the tide of public opinion in favor of Kelley ’ s cause . On March 25 of that year , a fire broke out at the Triangle Shirtwaist Company on the eighth floor of the Asch building in New York City , resulting in the deaths of 146 garment workers , most of them young , immigrant women ( Figure 21.8 ) . Management had previously blockaded doors and fire escapes in an effort to control workers and keep out union organizers ; in the blaze , many died due to the crush of bodies trying to evacuate the building . Others died when they fell off the flimsy fire escape or jumped to their deaths to escape the flames . This tragedy provided the National Consumers League with the moral argument to convince politicians of the need to pass workplace safety laws and codes . <hl> The Progressives ’ work towards social justice took many forms . <hl> <hl> In some cases , it was focused on those who suffered due to pervasive inequality , such as African Americans , other ethnic groups , and women . <hl> In others , the goal was to help those who were in desperate need due to circumstance , such as poor immigrants from southern and eastern Europe who often suffered severe discrimination , the working poor , and those with ill health . Women were in the vanguard of social justice reform . Jane Addams , Lillian Wald , and Ellen Gates Starr , for example , led the settlement house movement of the 1880s ( discussed in a previous chapter ) . <hl> Their work to provide social services , education , and health care to working-class women and their children was among the earliest Progressive grassroots efforts in the country . <hl>", "hl_sentences": "Another cause that garnered support from a key group of Progressives was the prohibition of liquor . This crusade , which gained followers through the Woman ’ s Christian Temperance Union ( WCTU ) and the Anti-Saloon League , directly linked Progressivism with morality and Christian reform initiatives , and saw in alcohol both a moral vice and a practical concern , as workingmen spent their wages on liquor and saloons , often turning violent towards each other or their families at home . Florence Kelley , a Progressive supporter of the NCLC , championed other social justice causes as well . As the first general secretary of the National Consumers League , which was founded in 1899 by Jane Addams and others , Kelley led one of the original battles to try and secure safety in factory working conditions . The Progressives ’ work towards social justice took many forms . In some cases , it was focused on those who suffered due to pervasive inequality , such as African Americans , other ethnic groups , and women . Their work to provide social services , education , and health care to working-class women and their children was among the earliest Progressive grassroots efforts in the country .", "question": { "cloze_format": "___ is not an example of social justice Progressivism.", "normal_format": "Which of the following is not an example of social justice Progressivism?", "question_choices": [ "anti-liquor campaigns", "referendums", "workplace safety initiatives", "improvements in education" ], "question_id": "fs-idp1462368", "question_text": "Which of the following is not an example of social justice Progressivism?" }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 2, "ans_text": "immediate protests for equal rights" }, "bloom": null, "hl_context": "Yet , many African Americans disagreed with Washington ’ s approach . Much in the same manner that Alice Paul felt the pace of the struggle for women ’ s rights was moving too slowly under the NAWSA , some within the African American community felt that immediate agitation for the rights guaranteed under the Thirteenth , Fourteenth , and Fifteenth Amendments , established during the immediate aftermath of the Civil War , was necessary . In 1905 , a group of prominent civil rights leaders , led by W . E . B . Du Bois , met in a small hotel on the Canadian side of Niagara Falls — where segregation laws did not bar them from hotel accommodations — to discuss what immediate steps were needed for equal rights ( Figure 21.15 ) . Du Bois , a professor at the all-Black Atlanta University and the first African American with a doctorate from Harvard , emerged as the prominent spokesperson for what would later be dubbed the Niagara Movement . <hl> By 1905 , he had grown wary of Booker T . Washington ’ s calls for African Americans to accommodate White racism and focus solely on self-improvement . <hl> <hl> Du Bois , and others alongside him , wished to carve a more direct path towards equality that drew on the political leadership and litigation skills of the Black , educated elite , which he termed the “ talented tenth . ” At the meeting , Du Bois led the others in drafting the “ Declaration of Principles , ” which called for immediate political , economic , and social equality for African Americans . <hl> These rights included universal suffrage , compulsory education , and the elimination of the convict lease system in which tens of thousands of Blacks had endured slavery-like conditions in southern road construction , mines , prisons , and penal farms since the end of Reconstruction . Within a year , Niagara chapters had sprung up in twenty-one states across the country . By 1908 , internal fights over the role of women in the fight for African American equal rights lessened the interest in the Niagara Movement . But the movement laid the groundwork for the creation of the National Association for the Advancement of Colored People ( NAACP ) , founded in 1909 . Du Bois served as the influential director of publications for the NAACP from its inception until 1933 . As the editor of the journal The Crisis , Du Bois had a platform to express his views on a variety of issues facing African Americans in the later Progressive Era , as well as during World War I and its aftermath . In both Washington and Du Bois , African Americans found leaders to push forward the fight for their place in the new century , each with a very different strategy . Both men cultivated ground for a new generation of African American spokespeople and leaders who would then pave the road to the modern civil rights movement after World War II . 21.4 Progressivism in the White House Learning Objectives By the end of this section , you will be able to : In a speech delivered at the Cotton States and International Exposition in Atlanta in 1895 , which was meant to promote the economy of a “ New South , ” Washington proposed what came to be known as the Atlanta Compromise ( Figure 21.14 ) . <hl> Speaking to a racially mixed audience , Washington called upon African Americans to work diligently for their own uplift and prosperity rather than preoccupy themselves with political and civil rights . <hl> <hl> Their success and hard work , he implied , would eventually convince southern Whites to grant these rights . <hl> Not surprisingly , most Whites liked Washington ’ s model of race relations , since it placed the burden of change on Blacks and required nothing of them . Wealthy industrialists such as Andrew Carnegie and John D . Rockefeller provided funding for many of Washington ’ s self-help programs , as did Sears , Roebuck & Co . co-founder Julius Rosenwald , and Washington was the first African American invited to the White House by President Roosevelt in 1901 . At the same time , his message also appealed to many in the Black community , and some attribute this widespread popularity to his consistent message that social and economic growth , even within a segregated society , would do more for African Americans than an all-out agitation for equal rights on all fronts . <hl> Born into slavery in Virginia in 1856 , Booker T . Washington became an influential African American leader at the outset of the Progressive Era . <hl> In 1881 , he became the first principal for the Tuskegee Normal and Industrial Institute in Alabama , a position he held until he died in 1915 . Tuskegee was an all-Black “ normal school ” — an old term for a teachers ’ college — teaching African Americans a curriculum geared towards practical skills such as cooking , farming , and housekeeping . Graduates would often then travel through the South , teaching new farming and industrial techniques to rural communities . Washington extolled the school ’ s graduates to focus on the Black community ’ s self-improvement and prove that they were productive members of society even in freedom — something White Americans throughout the nation had always doubted .", "hl_sentences": "By 1905 , he had grown wary of Booker T . Washington ’ s calls for African Americans to accommodate White racism and focus solely on self-improvement . Du Bois , and others alongside him , wished to carve a more direct path towards equality that drew on the political leadership and litigation skills of the Black , educated elite , which he termed the “ talented tenth . ” At the meeting , Du Bois led the others in drafting the “ Declaration of Principles , ” which called for immediate political , economic , and social equality for African Americans . Speaking to a racially mixed audience , Washington called upon African Americans to work diligently for their own uplift and prosperity rather than preoccupy themselves with political and civil rights . Their success and hard work , he implied , would eventually convince southern Whites to grant these rights . Born into slavery in Virginia in 1856 , Booker T . Washington became an influential African American leader at the outset of the Progressive Era .", "question": { "cloze_format": "____ was not a feature of Booker T. Washington's strategy to improve the lives of African Americans.", "normal_format": "Which of the following was not a feature of Booker T. Washington’s strategy to improve the lives of African Americans?", "question_choices": [ "self-help", "accommodating/tolerating White racism", "immediate protests for equal rights", "learning new trades/skills" ], "question_id": "fs-idm4273328", "question_text": "Which of the following was not a feature of Booker T. Washington’s strategy to improve the lives of African Americans?" }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 3, "ans_text": "D" }, "bloom": null, "hl_context": "For some in the NAWSA , however , the pace of change was too slow . Frustrated with the lack of response by state and national legislators , Alice Paul , who joined the organization in 1912 , sought to expand the scope of the organization as well as to adopt more direct protest tactics to draw greater media attention . When others in the group were unwilling to move in her direction , Paul split from the NAWSA to create the Congressional Union for Woman Suffrage , later renamed the National Woman ’ s Party , in 1913 . <hl> Known as the Silent Sentinels ( Figure 21.12 ) , Paul and her group picketed outside the White House for nearly two years , starting in 1917 . <hl> In the latter stages of their protests , many women , including Paul , were arrested and thrown in jail , where they staged a hunger strike as self-proclaimed political prisoners . Prison guards ultimately force-fed Paul to keep her alive . At a time — during World War I — when women volunteered as army nurses , worked in vital defense industries , and supported Wilson ’ s campaign to “ make the world safe for democracy , ” the scandalous mistreatment of Paul embarrassed President Woodrow Wilson . Enlightened to the injustice toward all American women , he changed his position in support of a woman ’ s constitutional right to vote . While Catt and Paul used different strategies , their combined efforts brought enough pressure to bear for Congress to pass the Nineteenth Amendment , which prohibited voter discrimination on the basis of sex , during a special session in the summer of 1919 . Subsequently , the required thirty-six states approved its adoption , with Tennessee doing so in August of 1920 , in time for that year ’ s presidential election .", "hl_sentences": "Known as the Silent Sentinels ( Figure 21.12 ) , Paul and her group picketed outside the White House for nearly two years , starting in 1917 .", "question": { "cloze_format": "The \"Silent Sentinels\" were ___.", "normal_format": "Who were the “Silent Sentinels”?", "question_choices": [ "a group of progressive African Americans who drafted the Declaration of Principles", "anti-suffrage women", "an offshoot of the Industrial Workers of the World", "suffragists who protested outside the White House" ], "question_id": "fs-idm55137504", "question_text": "Who were the “Silent Sentinels”?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 0, "ans_text": "A" }, "bloom": null, "hl_context": "In 1902 , Roosevelt launched his administration ’ s first antitrust suit against the Northern Securities Trust Company , which included powerful businessmen , like John D . Rockefeller and J . P . Morgan , and controlled many of the large midwestern railroads . The suit wound through the judicial system , all the way to the U . S . Supreme Court . In 1904 , the highest court in the land ultimately affirmed the ruling to break up the trust in a narrow five-to-four vote . For Roosevelt , that was enough of a mandate ; he immediately moved against other corporations as well , including the American Tobacco Company and — most significantly — Rockefeller ’ s Standard Oil Company . Although Roosevelt enjoyed the nickname “ the Trustbuster , ” he did not consider all trusts dangerous to the public welfare . The “ good trusts , ” Roosevelt reasoned , used their power in the marketplace and economies of scale to deliver goods and services to customers more cheaply . For example , he allowed Morgan ’ s U . S . Steel Corporation to continue its operations and let it take over smaller steel companies . At the same time , Roosevelt used the presidency as a “ bully pulpit ” to publicly denounce “ bad trusts ” — those corporations that exploited their market positions for short-term gains — before he ordered prosecutions by the Justice Department . In total , Roosevelt initiated over two dozen successful anti-trust suits , more than any president before him . Roosevelt also showed in other contexts that he dared to face the power of corporations . <hl> When an anthracite coal strike gripped the nation for much of the year in 1902 , Roosevelt directly intervened in the dispute and invited both sides to the White House to negotiate a deal that included minor wage increases and a slight improvement in working hours . <hl> For Roosevelt , his intervention in the matter symbolized his belief that the federal government should adopt a more proactive role and serve as a steward of all Americans ( Figure 21.17 ) . This stood in contrast to his predecessors , who had time and again bolstered industrialists in their fight against workers ’ rights with the deployment of federal troops .", "hl_sentences": "When an anthracite coal strike gripped the nation for much of the year in 1902 , Roosevelt directly intervened in the dispute and invited both sides to the White House to negotiate a deal that included minor wage increases and a slight improvement in working hours .", "question": { "cloze_format": "Roosevelt interceded in the Anthracite Coal Strike of 1902 ___.", "normal_format": "How did Roosevelt intercede in the Anthracite Coal Strike of 1902?", "question_choices": [ "He invited strikers and workers to the White House.", "He urged the owners to negotiate a deal.", "He threatened to send in the army to work the mines.", "He ordered the National Guard to protect the strikers." ], "question_id": "fs-idp6155392", "question_text": "How did Roosevelt intercede in the Anthracite Coal Strike of 1902?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 3, "ans_text": "the Payne-Aldrich Act" }, "bloom": null, "hl_context": "Political infighting within his own party exposed the limitations of Taft ’ s presidential authority , especially on the issue of protective tariffs . <hl> When House Republicans passed a measure to significantly reduce tariffs on several imported goods , Taft endorsed the Senate version , later known as the Payne-Aldrich Act of 1909 , which raised tariff rates on over eight hundred products in the original bill . <hl> <hl> Taft also angered Progressives in his own party when he created the U . S . Chamber of Commerce in 1912 , viewed by many as an attempt to offset the growing influence of the labor union movement at the time . <hl> The rift between Taft and his party ’ s Progressives widened when the president supported conservative party candidates for the 1910 House and Senate elections . Taft ’ s biggest political blunder came in the area of land conservation . In 1909 , Taft ’ s Secretary of the Interior , Richard Ballinger , approved the sale of millions of acres of federal land to a company for which he had previously worked over Gifford Pinchot ’ s objections . Pinchot publicly criticized the secretary for violating the principle of conservation and for his conflict of interest — a charge that in the public debate also reflected on the president . Taft fired Pinchot , a move that widened the gap between him and the former president . Upon his return from Africa , Roosevelt appeared primed to attack . He referred to the sitting president as a “ fathead ” and a “ puzzlewit , ” and announced his intention to “ throw my hat in the ring for the 1912 presidential election . ”", "hl_sentences": "When House Republicans passed a measure to significantly reduce tariffs on several imported goods , Taft endorsed the Senate version , later known as the Payne-Aldrich Act of 1909 , which raised tariff rates on over eight hundred products in the original bill . Taft also angered Progressives in his own party when he created the U . S . Chamber of Commerce in 1912 , viewed by many as an attempt to offset the growing influence of the labor union movement at the time .", "question": { "cloze_format": "___ was a key Progressive item passed by Taft.", "normal_format": "Which of the following was a key Progressive item passed by Taft?", "question_choices": [ "the Pure Food and Drug Act", "the U.S. Forestry Service", "the Mann-Elkins Act", "the Payne-Aldrich Act" ], "question_id": "fs-idm81830848", "question_text": "Which of the following was a key Progressive item passed by Taft?" }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 3, "ans_text": "D" }, "bloom": null, "hl_context": "When Wilson took office in March 1913 , he immediately met with Congress to outline his New Freedom agenda for how progressive interests could be best preserved . His plan was simple : regulate the banks and big businesses , and lower tariff rates to increase international trade , increasing competition in the interest of consumers . <hl> Wilson took the unusual step of calling a special session of Congress in April 1913 to tackle the tariff question , which resulted in the Revenue Act of 1913 , also known as the Underwood Tariff Act . <hl> <hl> This legislation lowered tariff rates across the board by approximately 15 percent and completely eliminated tariffs on several imports , including steel , iron ore , woolen products , and farm tools . <hl> To offset the potential loss of federal revenue , this new law reinstituted the federal income tax , which followed the ratification of the Sixteenth Amendment . This first income tax required married couples who earned $ 4000 or more , and single people who earned $ 3000 or more , to pay a 1 - percent , graduated income tax , with the tax rate getting progressively higher for those who earned more .", "hl_sentences": "Wilson took the unusual step of calling a special session of Congress in April 1913 to tackle the tariff question , which resulted in the Revenue Act of 1913 , also known as the Underwood Tariff Act . This legislation lowered tariff rates across the board by approximately 15 percent and completely eliminated tariffs on several imports , including steel , iron ore , woolen products , and farm tools .", "question": { "cloze_format": "___ was not an outcome of the Underwood Tariff Act.", "normal_format": "Which of the following was not an outcome of the Underwood Tariff Act?", "question_choices": [ "It reduced tariffs 15 percent across all imports.", "It eliminated tariffs for steel.", "It eliminated tariffs for iron ore.", "It established a federal banking system to oversee tariffs." ], "question_id": "fs-idp96060096", "question_text": "Which of the following was not an outcome of the Underwood Tariff Act?" }, "references_are_paraphrase": null } ]
21
21.1 The Origins of the Progressive Spirit in America Learning Objectives By the end of this section, you will be able to: Describe the role that muckrakers played in catalyzing the Progressive Era Explain the main features of Progressivism The Progressive Era was a time of wide-ranging causes and varied movements, where activists and reformers from diverse backgrounds and with very different agendas pursued their goals of a better America. These reformers were reacting to the challenges that faced the country at the end of the nineteenth century: rapid urban sprawl, immigration, corruption, industrial working conditions, the growth of large corporations, women’s rights, and surging anti-Black violence and White supremacy in the South. Investigative journalists of the day uncovered social inequality and encouraged Americans to take action. The campaigns of the Progressives were often grassroots in their origin. While different causes shared some underlying elements, each movement largely focused on its own goals, be it the right of women to vote, the removal of alcohol from communities, or the desire for a more democratic voting process. THE MUCKRAKERS A group of journalists and writers collectively known as muckrakers provided an important spark that ignited the Progressive movement. Unlike the “yellow journalists” who were interested only in sensationalized articles designed to sell newspapers, muckrakers exposed problems in American society and urged the public to identify solutions. Whether those problems were associated with corrupt machine politics, poor working conditions in factories, or the questionable living conditions of the working class (among others), muckrakers shined a light on the problem and provoked outraged responses from Americans. President Theodore Roosevelt knew many of these investigative journalists well and considered himself a Progressive. Yet, unhappy with the way they forced agendas into national politics, he was the one who first gave them the disparaging nickname “muckrakers,” invoking an ill-spirited character obsessed with filth from The Pilgrim’s Progress , a 1678 Christian allegory written by John Bunyan. Beginning in the second half of the nineteenth century, these Progressive journalists sought to expose critical social problems and exhort the public to take action. In his book, How the Other Half Lives (1890), journalist and photographer Jacob Riis used photojournalism to capture the dismal and dangerous living conditions in working-class tenements in New York City ( Figure 21.3 ). Ida Tarbell, perhaps the most well-known female muckraker, wrote a series of articles on the dangers of John D. Rockefeller’s powerful monopoly, Standard Oil. Her articles followed Henry Demarest Lloyd’s book, Wealth Against Commonwealth , published in 1894, which examined the excesses of Standard Oil. Other writers, like Lincoln Steffens, explored corruption in city politics, or, like Ray Stannard Baker, researched unsafe working conditions and low pay in the coal mines. The work of the muckrakers not only revealed serious problems in American society, but also agitated, often successfully, for change. Their articles, in magazines such as McClure’s , as well as books garnered attention for issues such as child labor, anti-trust, big business break-ups, and health and safety. Progressive activists took up these causes and lobbied for legislation to address some of the ills troubling industrial America. THE FEATURES OF PROGRESSIVISM Muckrakers drew public attention to some of the most glaring inequities and scandals that grew out of the social ills of the Gilded Age and the hands-off approach of the federal government since the end of Reconstruction. These writers by and large addressed a White, middle-class and elite, native-born audience, even though Progressive movements and organizations involved a diverse range of Americans. What united these Progressives beyond their different backgrounds and causes was a set of uniting principles, however. Most strove for a perfection of democracy, which required the expansion of suffrage to worthy citizens and the restriction of political participation for those considered “unfit” on account of health, education, or race. Progressives also agreed that democracy had to be balanced with an emphasis on efficiency, a reliance on science and technology, and deference to the expertise of professionals. They repudiated party politics but looked to government to regulate the modern market economy. And they saw themselves as the agents of social justice and reform, as well as the stewards and guides of workers and the urban poor. Often, reformers’ convictions and faith in their own expertise led them to dismiss the voices of the very people they sought to help. The expressions of these Progressive principles developed at the grassroots level. It was not until Theodore Roosevelt unexpectedly became president in 1901 that the federal government would engage in Progressive reforms. Before then, Progressivism was work done by the people, for the people. What knit Progressives together was the feeling that the country was moving at a dangerous pace in a dangerous direction and required the efforts of everyday Americans to help put it back on track. 21.2 Progressivism at the Grassroots Level Learning Objectives By the end of this section, you will be able to: Identify specific examples of grassroots Progressivism relating to the spread of democracy, efficiency in government, and social justice Describe the more radical movements associated with the Progressive Era A wide variety of causes fell under the Progressive label. For example, Wisconsin’s Robert M. (“Fighting Bob”) La Follette, one of the most Progressive politicians of his day, fought hard to curb the power of special interests in politics and reform the democratic process at state and local levels. Others sought out safer working conditions for factory workers. Different groups prioritized banning the sale of alcohol, which, they believed, was the root of much of the trouble for the working poor. No matter what the cause, Progressive campaigns often started with issues brought to the public’s attention by muckraking journalists. EXPANDING DEMOCRACY One of the key ideals that Progressives considered vital to the growth and health of the country was the concept of a perfected democracy. They felt, quite simply, that Americans needed to exert more control over their government. This shift, they believed, would ultimately lead to a system of government that was better able to address the needs of its citizens. Grassroots Progressives pushed forward their agenda of direct democracy through the passage of three state-level reforms . The first law involved the creation of the direct primary . Prior to this time, the only people who had a hand in selecting candidates for elections were delegates at conventions. Direct primaries allowed party members to vote directly for a candidate, with the nomination going to the one with the most votes. This was the beginning of the current system of holding a primary election before a general election. South Carolina adopted this system for statewide elections in 1896; in 1901, Florida became the first state to use the direct primary in nominations for the presidency. It is the method currently used in three-quarters of U.S. states. Another series of reforms pushed forward by Progressives that sought to sidestep the power of special interests in state legislatures and restore the democratic political process were three election innovations—the initiative , referendum , and recall . The first permitted voters to enact legislation by petitioning to place an idea, or initiative, on the ballot. In 1898, South Dakota became the first state to allow initiatives to appear on a ballot. By 1920, twenty states had adopted the procedure. The second innovation allowed voters to counteract legislation by holding a referendum—that is, putting an existing law on the ballot for voters to either affirm or reject. Currently twenty-four states allow some form of initiative and referendum. The third element of this direct democracy agenda was the recall. The recall permitted citizens to remove a public official from office through a process of petition and vote, similar to the initiative and referendum. While this measure was not as widely adopted as the others, Oregon, in 1910, became the first state to allow recalls. By 1920, twelve states had adopted this tool. It has only been used successfully a handful of times on the statewide level, for example, to remove the governor of North Dakota in 1921, and, more recently, the governor of California in 2003. Progressives also pushed for democratic reform that affected the federal government. In an effort to achieve a fairer representation of state constituencies in the U.S. Congress, they lobbied for approval of the Seventeenth Amendment to the U.S. Constitution, which mandated the direct election of U.S. senators. The Seventeenth Amendment replaced the previous system of having state legislatures choose senators. William Jennings Bryan, the 1896 Democratic presidential candidate who received significant support from the Populist Party, was among the leading Progressives who championed this cause. EXPERTISE AND EFFICIENCY In addition to making government more directly accountable to the voters, Progressives also fought to rid politics of inefficiency, waste, and corruption. Progressives in large cities were particularly frustrated with the corruption and favoritism of machine politics, which wasted enormous sums of taxpayer money and ultimately stalled the progress of cities for the sake of entrenched politicians, like the notorious Democratic Party Boss William Tweed in New York’s Tammany Hall. Progressives sought to change this corrupt system and had success in places like Galveston, Texas, where, in 1901, they pushed the city to adopt a commission system. A hurricane the previous year ( Figure 21.4 ) had led to the collapse of the old city government, which had proved incapable of leading the city through the natural disaster. The storm claimed over eight thousand lives—the highest death toll from a natural disaster in the history of the country—and afterwards, the community had no faith that the existing government could rebuild. The commission system involved the election of a number of commissioners, each responsible for one specific operation of the city, with titles like water commissioner, fire commissioner, police commissioner, and so on. With no single political “boss” in charge, the prevalence of graft and corruption greatly decreased. The commissioner system is widely used in modern cities throughout the United States. Another model of municipal government reform took shape in Staunton, Virginia, in 1908, where the citizens switched to the city manager form of government. Designed to avoid the corruption inherent in political machines, the city manager system separated the daily operations of the city from both the electoral process and political parties. In this system, citizens elected city councilors who would pass laws and handle all legislative issues. However, their first job was to hire a city manager to deal with the daily management operation of the city. This person, unlike the politicians, was an engineer or businessman who understood the practical elements of city operations and oversaw city workers. Currently, over thirty-seven hundred cities have adopted the city manager system, including some of the largest cities in the country, such as Austin, Dallas, and Phoenix. At the state level, perhaps the greatest advocate of Progressive government was Robert La Follette ( Figure 21.5 ). During his time as governor, from 1901 through 1906, La Follette introduced the Wisconsin Idea , wherein he hired experts to research and advise him in drafting legislation to improve conditions in his state. “Fighting Bob” supported numerous Progressive ideas while governor: He signed into law the first workman’s compensation system, approved a minimum wage law, developed a progressive tax law, adopted the direct election of U.S. senators before the subsequent constitutional amendment made it mandatory, and advocated for women’s suffrage. La Follette subsequently served as a popular U.S. senator from Wisconsin from 1906 through 1925, and ran for president on the Progressive Party ticket in 1924. Many Progressive reformers were also committed to the principle of efficiency in business as well as in government. The growth of large corporations at the time fostered the emergence of a class of professional managers. Fredrick Winslow Taylor, arguably the first American management consultant, laid out his argument of increased industrial efficiency through improvements in human productivity in his book The Principles of Scientific Management (1911). Through time-motion studies and the principles of standardization, Taylor sought to place workers in the most efficient positions of the industrial process. Management, he argued, should determine the work routine, leaving workers to simply execute the task at hand. The image below ( Figure 21.6 ) shows a machinist in a factory where Taylor had consulted; he is alone and focused solely on his job. Progressive in its emphasis on efficiency, the use of science, and the reliance on experts, Taylorism , as scientific management became known, was not widely popular among workers who resented managerial authority and the loss of autonomy over their work. Many workers went on strikes in response, although some favored Taylor’s methods, since their pay was directly linked to the productivity increases that his methods achieved and since increased efficiency allowed companies to charge consumers lower prices. SOCIAL JUSTICE The Progressives’ work towards social justice took many forms. In some cases, it was focused on those who suffered due to pervasive inequality, such as African Americans, other ethnic groups, and women. In others, the goal was to help those who were in desperate need due to circumstance, such as poor immigrants from southern and eastern Europe who often suffered severe discrimination, the working poor, and those with ill health. Women were in the vanguard of social justice reform. Jane Addams, Lillian Wald, and Ellen Gates Starr, for example, led the settlement house movement of the 1880s (discussed in a previous chapter). Their work to provide social services, education, and health care to working-class women and their children was among the earliest Progressive grassroots efforts in the country. Building on the successes of the settlement houses, social justice reformers took on other, related challenges. The National Child Labor Committee (NCLC), formed in 1904, urged the passage of labor legislation to ban child labor in the industrial sector. In 1900, U.S. census records indicated that one out of every six children between the ages of five and ten were working, a 50-percent increase over the previous decade. If the sheer numbers alone were not enough to spur action, the fact that managers paid child workers noticeably less for their labor gave additional fuel to the NCLC’s efforts to radically curtail child labor. The committee employed photographer Lewis Hine to engage in a decade-long pictorial campaign to educate Americans on the plight of children working in factories ( Figure 21.7 ). Although low-wage industries fiercely opposed any federal restriction on child labor, the NCLC did succeed in 1912, urging President William Howard Taft to sign into law the creation of the U.S. Children’s Bureau. As a branch of the Department of Labor, the bureau worked closely with the NCLC to bring greater awareness to the issue of child labor. In 1916, the pressure from the NCLC and the general public resulted in the passage of the Keating-Owen Act, which prohibited the interstate trade of any goods produced with child labor. Although the U.S. Supreme Court later declared the law unconstitutional, Keating-Owen reflected a significant shift in the public perception of child labor. Finally, in 1938, the passage of the Fair Labor Standards Act signaled the victory of supporters of Keating-Owen. This new law outlawed the interstate trade of any products produced by children under the age of sixteen. Florence Kelley, a Progressive supporter of the NCLC, championed other social justice causes as well. As the first general secretary of the National Consumers League, which was founded in 1899 by Jane Addams and others, Kelley led one of the original battles to try and secure safety in factory working conditions. She particularly opposed sweatshop labor and urged the passage of an eight-hour-workday law in order to specifically protect women in the workplace. Kelley’s efforts were initially met with strong resistance from factory owners who exploited women’s labor and were unwilling to give up the long hours and low wages they paid in order to offer the cheapest possible product to consumers. But in 1911, a tragedy turned the tide of public opinion in favor of Kelley’s cause. On March 25 of that year, a fire broke out at the Triangle Shirtwaist Company on the eighth floor of the Asch building in New York City, resulting in the deaths of 146 garment workers, most of them young, immigrant women ( Figure 21.8 ). Management had previously blockaded doors and fire escapes in an effort to control workers and keep out union organizers; in the blaze, many died due to the crush of bodies trying to evacuate the building. Others died when they fell off the flimsy fire escape or jumped to their deaths to escape the flames. This tragedy provided the National Consumers League with the moral argument to convince politicians of the need to pass workplace safety laws and codes. My Story William Shepherd on the Triangle Shirtwaist Factory Fire The tragedy of the Triangle Shirtwaist Factory fire was a painful wake-up call to a country that was largely ignoring issues of poor working conditions and worker health and safety. While this fire was far from the only instance of worker death, the sheer number of people killed—almost one hundred fifty—and the fact they were all young women, made a strong impression. Furthering the power of this tragedy was the first-hand account shared by William Shepherd, a United Press reporter who was on the scene, giving his eyewitness account over a telephone. His account appeared, just two days later, in the Milwaukee Journal , and word of the tragedy spread from there. Public outrage over their deaths was enough to give the National Consumers League the power it needed to push politicians to get involved. I saw every feature of the tragedy visible from outside the building. I learned a new sound—a more horrible sound than description can picture. It was the thud of a speeding, living body on a stone sidewalk. Thud-dead, thud-dead, thud-dead, thud-dead.Sixty-two thud-deads. I call them that, because the sound and the thought of death came to me each time, at the same instant. There was plenty of chance to watch them as they came down. The height was eighty feet. The first ten thud-deads shocked me. I looked up—saw that there were scores of girls at the windows. The flames from the floor below were beating in their faces. Somehow I knew that they, too, must come down. . . . A policeman later went about with tags, which he fastened with wires to the wrists of the dead girls, numbering each with a lead pencil, and I saw him fasten tag no. 54 to the wrist of a girl who wore an engagement ring. A fireman who came downstairs from the building told me that there were at least fifty bodies in the big room on the seventh floor. Another fireman told me that more girls had jumped down an air shaft in the rear of the building. I went back there, into the narrow court, and saw a heap of dead girls. . . . The floods of water from the firemen’s hose that ran into the gutter were actually stained red with blood. I looked upon the heap of dead bodies and I remembered these girls were the shirtwaist makers. I remembered their great strike of last year in which these same girls had demanded more sanitary conditions and more safety precautions in the shops. These dead bodies were the answer. What do you think about William Shepherd’s description? What effect do you think it had on newspaper readers in the Midwest? Another cause that garnered support from a key group of Progressives was the prohibition of liquor. This crusade, which gained followers through the Woman’s Christian Temperance Union (WCTU) and the Anti-Saloon League, directly linked Progressivism with morality and Christian reform initiatives, and saw in alcohol both a moral vice and a practical concern, as workingmen spent their wages on liquor and saloons, often turning violent towards each other or their families at home. The WCTU and Anti-Saloon League moved the efforts to eliminate the sale of alcohol from a bar-to-bar public opinion campaign to one of city-to-city and state-by-state votes ( Figure 21.9 ). Through local option votes and subsequent statewide initiatives and referendums, the Anti-Saloon League succeeded in urging 40 percent of the nation’s counties to “go dry” by 1906, and a full dozen states to do the same by 1909. Their political pressure culminated in the passage of the Eighteenth Amendment to the U.S. Constitution, ratified in 1919, which prohibited the manufacture, sale, and transportation of alcoholic beverages nationwide. RADICAL PROGRESSIVES The Progressive Era also witnessed a wave of radicalism, with leaders who believed that America was beyond reform and that only a complete revolution of sorts would bring about the necessary changes. The radicals had early roots in the labor and political movements of the mid-nineteenth century but soon grew to feel that the more moderate Progressive ideals were inadequate. Conversely, one reason why mainstream Progressives felt the need to succeed on issues of social inequity was because radicals offered remedies that middle-class Americans considered far more dangerous. The two most prominent radical movements to emerge at the beginning of the century were the Socialist Party of America (SPA), founded in 1901, and the Industrial Workers of the World (IWW), founded in 1905, whose emphasis on worker empowerment deviated from the more paternalistic approach of Progressive reformers. Labor leader Eugene Debs, disenchanted with the failures of the labor movement, was a founding member and prominent leader of the SPA ( Figure 21.10 ). Advocating for change via the ballot box, the SPA sought to elect Socialists to positions at the local, state, and federal levels in order to initiate change from within. Between 1901 and 1918, the SPA enjoyed tremendous success, electing over seventy Socialist mayors, over thirty state legislators, and two U.S. congressmen, Victor Berger from Wisconsin and Meyer London from New York. Debs himself ran for president as the SPA candidate in five elections between 1900 and 1920, twice earning nearly one million votes. As had been true for the Populist and Progressive movements, the radical movement suffered numerous fissures. Although Debs established a tenuous relationship with Samuel Gompers and the American Federation of Labor, some within the Socialist Party favored a more radical political stance than Debs’s craft union structure. As a result, William “Big Bill” Haywood formed the more radical IWW, or Wobblies , in 1905. Although he remained an active member of the Socialist Party until 1919, Haywood appreciated the outcry of the more radical arm of the party that desired an industrial union approach to labor organization. The IWW advocated for direct action and, in particular, the general strike, as the most effective revolutionary method to overthrow the capitalist system. By 1912, the Wobblies had played a significant role in a number of major strikes, including the Paterson Silk Strike, the Lawrence Textile Strike, and the Mesabi Range Iron Strike. The government viewed the Wobblies as a significant threat, and in a response far greater than their actions warranted, targeted them with arrests, tar-and-featherings, shootings, and lynchings. Both the Socialist Party and the IWW reflected elements of the Progressive desire for democracy and social justice. The difference was simply that for this small but vocal minority in the United States, the corruption of government at all levels meant that the desire for a better life required a different approach. What they sought mirrored the work of all grassroots Progressives, differing only in degree and strategy. 21.3 New Voices for Women and African Americans Learning Objectives By the end of this section, you will be able to: Understand the origins and growth of the women’s rights movement Identify the different strands of the early African American civil rights movement The Progressive drive for a more perfect democracy and social justice also fostered the growth of two new movements that attacked the oldest and most long-standing betrayals of the American promise of equal opportunity and citizenship—the disfranchisement of women and civil rights for African Americans. African Americans across the nation identified an agenda for civil rights and economic opportunity during the Progressive Era, but they disagreed strongly on how to meet these goals in the face of universal discrimination and disfranchisement, segregation, and racial violence in the South. And beginning in the late nineteenth century, the women’s movement cultivated a cadre of new leaders, national organizations, and competing rationales for women’s rights—especially the right to vote. LEADERS EMERGE IN THE WOMEN’S MOVEMENT Women like Jane Addams and Florence Kelley were instrumental in the early Progressive settlement house movement, and female leaders dominated organizations such as the WCTU and the Anti-Saloon League. From these earlier efforts came new leaders who, in their turn, focused their efforts on the key goal of the Progressive Era as it pertained to women: the right to vote. Women had first formulated their demand for the right to vote in the Declaration of Sentiments at a convention in Seneca Falls, New York, in 1848, and saw their first opportunity of securing suffrage during Reconstruction when legislators—driven by racial animosity—sought to enfranchise women to counter the votes of Black men following the ratification of the Fifteenth Amendment. By 1900, the western frontier states of Colorado, Idaho, Utah, and Wyoming had already responded to women’s movements with the right to vote in state and local elections, regardless of gender. They conceded to the suffragists’ demands, partly in order to attract more women to these male-dominated regions. But women’s lives in the West also rarely fit with the nineteenth-century ideology of “separate spheres” that had legitimized the exclusion of women from the rough-and-tumble party competitions of public politics. In 1890, the National American Women’s Suffrage Association (NAWSA) organized several hundred state and local chapters to urge the passage of a federal amendment to guarantee a woman’s right to vote. Its leaders, Elizabeth Cady Stanton and Susan B. Anthony, were veterans of the women’s suffrage movement and had formulated the first demand for the right to vote at Seneca Falls in 1848 ( Figure 21.11 ). Under the subsequent leadership of Carrie Chapman Catt, beginning in 1900, the group decided to make suffrage its first priority. Soon, its membership began to grow. Using modern marketing efforts like celebrity endorsements to attract a younger audience, the NAWSA became a significant political pressure group for the passage of an amendment to the U.S. Constitution. For some in the NAWSA, however, the pace of change was too slow. Frustrated with the lack of response by state and national legislators, Alice Paul, who joined the organization in 1912, sought to expand the scope of the organization as well as to adopt more direct protest tactics to draw greater media attention. When others in the group were unwilling to move in her direction, Paul split from the NAWSA to create the Congressional Union for Woman Suffrage, later renamed the National Woman’s Party, in 1913. Known as the Silent Sentinels ( Figure 21.12 ), Paul and her group picketed outside the White House for nearly two years, starting in 1917. In the latter stages of their protests, many women, including Paul, were arrested and thrown in jail, where they staged a hunger strike as self-proclaimed political prisoners. Prison guards ultimately force-fed Paul to keep her alive. At a time—during World War I—when women volunteered as army nurses, worked in vital defense industries, and supported Wilson’s campaign to “make the world safe for democracy,” the scandalous mistreatment of Paul embarrassed President Woodrow Wilson. Enlightened to the injustice toward all American women, he changed his position in support of a woman’s constitutional right to vote. While Catt and Paul used different strategies, their combined efforts brought enough pressure to bear for Congress to pass the Nineteenth Amendment, which prohibited voter discrimination on the basis of sex, during a special session in the summer of 1919. Subsequently, the required thirty-six states approved its adoption, with Tennessee doing so in August of 1920, in time for that year’s presidential election. Defining American The Anti-Suffragist Movement The early suffragists may have believed that the right to vote was a universal one, but they faced waves of discrimination and ridicule from both men and women. The image below ( Figure 21.13 ) shows one of the organizations pushing back against the suffragist movement, but much of the anti-suffrage campaign was carried out through ridiculing postcards and signs that showed suffragists as sexually wanton, grasping, irresponsible, or impossibly ugly. Men in anti-suffragist posters were depicted as henpecked, crouching to clean the floor, while their suffragist wives marched out the door to campaign for the vote. They also showed cartoons of women gambling, drinking, and smoking cigars, that is, taking on men’s vices, once they gained voting rights. Other anti-suffragists believed that women could better influence the country from outside the realm of party politics, through their clubs, petitions, and churches. Many women also opposed women’s suffrage because they thought the dirty world of politics was a morass to which ladies should not be exposed. The National Association Opposed to Woman Suffrage formed in 1911; around the country, state representatives used the organization’s speakers, funds, and literature to promote the anti-suffragist cause. As the link below illustrates, the suffragists endured much prejudice and backlash in their push for equal rights. LEADERS EMERGE IN THE EARLY CIVIL RIGHTS MOVEMENT Racial mob violence against African Americans permeated much of the “New South”—and, to a lesser extent, the West, where Mexican Americans and other immigrant groups also suffered severe discrimination and violence—by the late nineteenth century. The Ku Klux Klan and a system of Jim Crow laws governed much of the South (discussed in a previous chapter). White middle-class reformers were appalled at the violence of race relations in the nation but typically shared the belief in racial characteristics and the superiority of Anglo-Saxon Whites over African Americans, Asians, “ethnic” Europeans, Native Americans, and Latin American populations. Southern reformers considered segregation a Progressive solution to racial violence; across the nation, educated middle-class Americans enthusiastically followed the work of eugenicists who identified virtually all human behavior as inheritable traits and issued awards at county fairs to families and individuals for their “racial fitness.” It was against this tide that African American leaders developed their own voice in the Progressive Era, working along diverse paths to improve the lives and conditions of African Americans throughout the country. Born into slavery in Virginia in 1856, Booker T. Washington became an influential African American leader at the outset of the Progressive Era. In 1881, he became the first principal for the Tuskegee Normal and Industrial Institute in Alabama, a position he held until he died in 1915. Tuskegee was an all-Black “normal school”—an old term for a teachers’ college—teaching African Americans a curriculum geared towards practical skills such as cooking, farming, and housekeeping. Graduates would often then travel through the South, teaching new farming and industrial techniques to rural communities. Washington extolled the school’s graduates to focus on the Black community’s self-improvement and prove that they were productive members of society even in freedom—something White Americans throughout the nation had always doubted. In a speech delivered at the Cotton States and International Exposition in Atlanta in 1895, which was meant to promote the economy of a “New South,” Washington proposed what came to be known as the Atlanta Compromise ( Figure 21.14 ). Speaking to a racially mixed audience, Washington called upon African Americans to work diligently for their own uplift and prosperity rather than preoccupy themselves with political and civil rights. Their success and hard work, he implied, would eventually convince southern Whites to grant these rights. Not surprisingly, most Whites liked Washington’s model of race relations, since it placed the burden of change on Blacks and required nothing of them. Wealthy industrialists such as Andrew Carnegie and John D. Rockefeller provided funding for many of Washington’s self-help programs, as did Sears, Roebuck & Co. co-founder Julius Rosenwald, and Washington was the first African American invited to the White House by President Roosevelt in 1901. At the same time, his message also appealed to many in the Black community, and some attribute this widespread popularity to his consistent message that social and economic growth, even within a segregated society, would do more for African Americans than an all-out agitation for equal rights on all fronts. Yet, many African Americans disagreed with Washington’s approach. Much in the same manner that Alice Paul felt the pace of the struggle for women’s rights was moving too slowly under the NAWSA, some within the African American community felt that immediate agitation for the rights guaranteed under the Thirteenth, Fourteenth, and Fifteenth Amendments, established during the immediate aftermath of the Civil War, was necessary. In 1905, a group of prominent civil rights leaders, led by W. E. B. Du Bois, met in a small hotel on the Canadian side of Niagara Falls—where segregation laws did not bar them from hotel accommodations—to discuss what immediate steps were needed for equal rights ( Figure 21.15 ). Du Bois, a professor at the all-Black Atlanta University and the first African American with a doctorate from Harvard, emerged as the prominent spokesperson for what would later be dubbed the Niagara Movement . By 1905, he had grown wary of Booker T. Washington’s calls for African Americans to accommodate White racism and focus solely on self-improvement. Du Bois, and others alongside him, wished to carve a more direct path towards equality that drew on the political leadership and litigation skills of the Black, educated elite, which he termed the “talented tenth.” At the meeting, Du Bois led the others in drafting the “Declaration of Principles,” which called for immediate political, economic, and social equality for African Americans. These rights included universal suffrage, compulsory education, and the elimination of the convict lease system in which tens of thousands of Blacks had endured slavery-like conditions in southern road construction, mines, prisons, and penal farms since the end of Reconstruction. Within a year, Niagara chapters had sprung up in twenty-one states across the country. By 1908, internal fights over the role of women in the fight for African American equal rights lessened the interest in the Niagara Movement. But the movement laid the groundwork for the creation of the National Association for the Advancement of Colored People ( NAACP ), founded in 1909. Du Bois served as the influential director of publications for the NAACP from its inception until 1933. As the editor of the journal The Crisis , Du Bois had a platform to express his views on a variety of issues facing African Americans in the later Progressive Era, as well as during World War I and its aftermath. In both Washington and Du Bois, African Americans found leaders to push forward the fight for their place in the new century, each with a very different strategy. Both men cultivated ground for a new generation of African American spokespeople and leaders who would then pave the road to the modern civil rights movement after World War II. 21.4 Progressivism in the White House Learning Objectives By the end of this section, you will be able to: Explain the key features of Theodore Roosevelt’s “Square Deal” Explain the key features of William Howard Taft’s Progressive agenda Identify the main pieces of legislation that Woodrow Wilson’s “New Freedom” agenda comprised Progressive groups made tremendous strides on issues involving democracy, efficiency, and social justice. But they found that their grassroots approach was ill-equipped to push back against the most powerful beneficiaries of growing inequality, economic concentration, and corruption—big business. In their fight against the trusts, Progressives needed the leadership of the federal government, and they found it in Theodore Roosevelt in 1901, through an accident of history. In 1900, a sound economic recovery, a unifying victory in the Spanish-American War, and the annexation of the Philippines had helped President William McKinley secure his reelection with the first solid popular majority since 1872. His new vice president was former New York Governor and Assistant Secretary of the Navy, Theodore Roosevelt. But when an assassin shot and killed President McKinley in 1901 ( Figure 21.16 ) at the Pan-American Exposition in Buffalo, New York, Theodore Roosevelt unexpectedly became the youngest president in the nation’s history. More importantly, it ushered in a new era of progressive national politics and changed the role of the presidency for the twentieth century. BUSTING THE TRUSTS Roosevelt’s early career showed him to be a dynamic leader with a Progressive agenda. Many Republican Party leaders disliked Roosevelt’s Progressive ideas and popular appeal and hoped to end his career with a nomination to the vice presidency—long considered a dead end in politics. When an assassin’s bullet toppled this scheme, Mark Hanna, a prominent Republican senator and party leader, lamented, “Now look! That damned cowboy is now president!” As the new president, however, Roosevelt moved cautiously with his agenda while he finished out McKinley’s term. Roosevelt kept much of McKinley’s cabinet intact, and his initial message to Congress gave only one overriding Progressive goal for his presidency: to eliminate business trusts. In the three years prior to Roosevelt’s presidency, the nation had witnessed a wave of mergers and the creation of mega-corporations. To counter this trend, Roosevelt created the Department of Commerce and Labor in 1903, which included the Bureau of Corporations, whose job it was to investigate trusts. He also asked the Department of Justice to resume prosecutions under the Sherman Antitrust Act of 1890. Intended to empower federal prosecutors to ban monopolies as conspiracies against interstate trade, the law had run afoul of a conservative Supreme Court. In 1902, Roosevelt launched his administration’s first antitrust suit against the Northern Securities Trust Company, which included powerful businessmen, like John D. Rockefeller and J. P. Morgan, and controlled many of the large midwestern railroads. The suit wound through the judicial system, all the way to the U.S. Supreme Court. In 1904, the highest court in the land ultimately affirmed the ruling to break up the trust in a narrow five-to-four vote. For Roosevelt, that was enough of a mandate; he immediately moved against other corporations as well, including the American Tobacco Company and—most significantly—Rockefeller’s Standard Oil Company. Although Roosevelt enjoyed the nickname “the Trustbuster,” he did not consider all trusts dangerous to the public welfare. The “good trusts,” Roosevelt reasoned, used their power in the marketplace and economies of scale to deliver goods and services to customers more cheaply. For example, he allowed Morgan’s U.S. Steel Corporation to continue its operations and let it take over smaller steel companies. At the same time, Roosevelt used the presidency as a “bully pulpit” to publicly denounce “bad trusts”—those corporations that exploited their market positions for short-term gains—before he ordered prosecutions by the Justice Department. In total, Roosevelt initiated over two dozen successful anti-trust suits, more than any president before him. Roosevelt also showed in other contexts that he dared to face the power of corporations. When an anthracite coal strike gripped the nation for much of the year in 1902, Roosevelt directly intervened in the dispute and invited both sides to the White House to negotiate a deal that included minor wage increases and a slight improvement in working hours. For Roosevelt, his intervention in the matter symbolized his belief that the federal government should adopt a more proactive role and serve as a steward of all Americans ( Figure 21.17 ). This stood in contrast to his predecessors, who had time and again bolstered industrialists in their fight against workers’ rights with the deployment of federal troops. THE SQUARE DEAL Roosevelt won his second term in 1904 with an overwhelming 57 percent of the popular vote. After the election, he moved quickly to enact his own brand of Progressivism, which he called a Square Deal for the American people. Early in his second term, Roosevelt read muckraker Upton Sinclair’s 1905 novel and exposé on the meatpacking industry, The Jungle . Although Roosevelt initially questioned the book due to Sinclair’s professed Socialist leanings, a subsequent presidential commission investigated the industry and corroborated the deplorable conditions under which Chicago’s meatpackers processed meats for American consumers. Alarmed by the results and under pressure from an outraged public disgusted with the revelations, Roosevelt moved quickly to protect public health. He urged the passage of two laws to do so. The first, the Meat Inspection Act of 1906, established a system of government inspection for meat products, including grading the meat based on its quality. This standard was also used for imported meats. The second was the Pure Food and Drug Act of 1906, which required labels on all food and drug products that clearly stated the materials in the product. The law also prohibited any “adulterated” products, a measure aimed at some specific, unhealthy food preservatives. For Sinclair, this outcome was a disappointment nonetheless, since he had sought to draw attention to the plight of workers in the slaughterhouses, not the poor quality of the meat products. “I aimed at the public’s heart, and by accident I hit it in the stomach,” he concluded with frustration. Another key element of Roosevelt’s Progressivism was the protection of public land ( Figure 21.18 ). Roosevelt was a longtime outdoorsman, with an interest that went back to his childhood and college days, as well as his time cattle ranching in the West, and he chose to appoint his good friend Gifford Pinchot as the country’s first chief of the newly created U.S. Forestry Service. Under Pinchot’s supervision, the department carved out several nature habitats on federal land in order to preserve the nation’s environmental beauty and protect it from development or commercial use. Apart from national parks like Oregon’s Crater Lake or Colorado’s Mesa Verde, and monuments designed for preservation, Roosevelt conserved public land for regulated use for future generations. To this day, the 150 national forests created under Roosevelt’s stewardship carry the slogan “land of many uses.” In all, Roosevelt established eighteen national monuments, fifty-one federal bird preserves, five national parks, and over one hundred fifty national forests, which amounted to about 230 million acres of public land. In his second term in office, Roosevelt signed legislation on Progressive issues such as factory inspections, child labor, and business regulation. He urged the passage of the Elkins Act of 1903 and the Hepburn Act of 1906, both of which strengthened the position of the Interstate Commerce Commission to regulate railroad prices. These laws also extended the Commission’s authority to regulate interstate transportation on bridges, ferries, and even oil pipelines. As the 1908 election approached, Roosevelt was at the height of popularity among the American public, if not among the big businesses and conservative leaders of his own Republican Party. Nonetheless, he promised on the night of his reelection in 1904 that he would not seek a third term. Roosevelt stepped aside as the election approached, but he did hand-pick a successor—Secretary of War and former Governor General of the Philippines William Howard Taft of Ohio—a personal friend who, he assured the American public, would continue the path of the “Square Deal” ( Figure 21.19 ). With such a ringing endorsement, Taft easily won the 1908 presidential election, defeating three-time Democratic presidential nominee William Jennings Bryan, whose ideas on taxes and corporate regulations reminded voters of the more far-reaching Populist platforms of Bryan’s past candidacies. THE TAFT PRESIDENCY Although six feet tall and nearly 340 pounds, as Roosevelt’s successor, Taft had big shoes to fill. The public expected much from Roosevelt’s hand-picked replacement, as did Roosevelt himself, who kept a watchful eye over Taft’s presidency. The new president’s background suggested he would be a strong administrator. He had previously served as the governor of the Philippines following the Spanish-American War , had a distinguished judicial career, and served as Roosevelt’s Secretary of War from 1904 to 1908. Republican leaders, however, were anxious to reestablish tighter control over the party after Roosevelt’s departure, and they left Taft little room to maneuver. He stayed the course of his predecessor by signing the Mann-Elkins Act of 1910, which extended the authority of the Interstate Commerce Commission over telephones and telegraphs. Additionally, during his tenure, Congress proposed constitutional amendments to authorize a federal income tax and mandate the direct election of U.S. senators. But even though Taft initiated twice as many antitrust suits against big business as Roosevelt, he lacked the political negotiating skills and focus on the public good of his predecessor, who felt betrayed when Taft took J.P. Morgan’s U.S. Steel Corporation to court over an acquisition that Roosevelt had promised Morgan would not result in a prosecution. Political infighting within his own party exposed the limitations of Taft’s presidential authority, especially on the issue of protective tariffs. When House Republicans passed a measure to significantly reduce tariffs on several imported goods, Taft endorsed the Senate version, later known as the Payne-Aldrich Act of 1909, which raised tariff rates on over eight hundred products in the original bill. Taft also angered Progressives in his own party when he created the U.S. Chamber of Commerce in 1912, viewed by many as an attempt to offset the growing influence of the labor union movement at the time. The rift between Taft and his party’s Progressives widened when the president supported conservative party candidates for the 1910 House and Senate elections. Taft’s biggest political blunder came in the area of land conservation. In 1909, Taft’s Secretary of the Interior, Richard Ballinger, approved the sale of millions of acres of federal land to a company for which he had previously worked over Gifford Pinchot’s objections. Pinchot publicly criticized the secretary for violating the principle of conservation and for his conflict of interest—a charge that in the public debate also reflected on the president. Taft fired Pinchot, a move that widened the gap between him and the former president. Upon his return from Africa, Roosevelt appeared primed to attack. He referred to the sitting president as a “fathead” and a “puzzlewit,” and announced his intention to “throw my hat in the ring for the 1912 presidential election.” THE 1912 PRESIDENTIAL ELECTION Although not as flamboyant or outwardly progressive as Roosevelt, Taft’s organizational skills and generally solid performance as president aligned with the party leadership’s concerns over another Roosevelt presidency and secured for him the Republican Party’s nomination. Angry over this snub, in 1912, Roosevelt and the other Progressive Republicans bolted from the Republican Party and formed the Progressive Party . His popularity had him hoping to win the presidential race as a third-party candidate. When he survived an assassination attempt in Milwaukee, Wisconsin, in October 1912—the assassin’s bullet hit his eyeglass case and only injured him superficially—he turned the near-death experience into a political opportunity. Insisting upon delivering the speech before seeking medical attention, he told the crowd, “It takes more than a bullet to kill a bull moose!” The moniker stuck, and Roosevelt’s Progressive Party would be known as the Bull Moose Party for the remainder of the campaign ( Figure 21.20 ). The Democrats realized that a split Republican Party gave them a good chance of regaining the White House for the first time since 1896. They found their candidate in the Progressive governor of New Jersey, Woodrow Wilson. A former history professor and president at Princeton University, Wilson had an academic demeanor that appealed to many Progressive reformers. Many Democrats also viewed Wilson as a Washington outsider who had made far fewer political enemies than Roosevelt and Taft. Taft never truly campaigned for the post, did not deliver a single speech, and did not seem like a serious contender. In their campaigns, Roosevelt and Wilson formulated competing Progressive platforms. Wilson described his more moderate approach as one of New Freedom , which stood for a smaller federal government to protect public interests from the evils associated with big businesses and banks. Roosevelt campaigned on the promise of New Nationalism , a charge that he said required a vigorous and powerful federal government to protect public interests. He sought to capitalize on the stewardship approach that he had made famous during his previous administration. Wilson won the 1912 election with over six million votes, with four million votes going to Roosevelt and three and one-half million for Taft. The internal split among Republicans not only cost them the White House but control of the Senate as well—and Democrats had already won a House majority in 1910. Wilson won the presidency with just 42 percent of the popular vote, which meant that he would have to sway a large number of voters should he have any aspirations for a second term. Defining American The Unprecedented Election of 1912 In his 2002 article on the 1912 election, historian Sidney M. Milkis writes, The Progressive Party’s “compromise” with public opinion in the United States points to its legacy for American politics and government. Arguably, the failure of the 1912 experiment and the Progressive Party’s demise underscore the incoherence of the Progressive movement. Nevertheless, it was neither the Democrats, nor the Republicans, nor the Socialists who set the tone of the 1912 campaign. It was the Progressives. Beyond the 1912 election, their program of political and social reform has been an enduring feature of American political discourse and electoral struggle. The Progressive Party forged a path of reform that left both social democracy and conservatism—Taft’s constitutional sobriety—behind. Similarly, T.R.’s celebrity, and the popularity of the Progressive doctrine of the people’s right to rule, tended to subordinate the more populist to the more plebiscitary schemes in the platform, such as the initiative, the referendum, and the direct primary, which exalted not the “grass roots” but mass opinion. Indeed, in the wake of the excitement aroused by the Progressive Party, Wilson, whose New Freedom campaign was far more sympathetic to the decentralized state of courts and parties than T.R.’s, felt compelled, as president, to govern as a New Nationalist Progressive. It is interesting to think of how this most unusual election—one with three major candidates that pitted a former president against an incumbent and a major party contender—related to the larger Progressive movement. The cartoon below is only one of many cartoons of that era that sought to point out the differences between the candidates ( Figure 21.21 ). While Roosevelt and the Progressive Party ultimately lost the election, they required the dialogue of the campaign to remain on the goals of Progressivism, particularly around more direct democracy and business regulation. The American public responded with fervor to Roosevelt’s campaign, partly because of his immense popularity, but partly also because he espoused a kind of direct democracy that gave people a voice in federal politics. Although Wilson and his New Freedom platform won the election, his presidency undertook a more activist role than his campaign suggested. The American public had made clear that, no matter who sat in the White House, they were seeking a more progressive America. WILSON’S NEW FREEDOM When Wilson took office in March 1913, he immediately met with Congress to outline his New Freedom agenda for how progressive interests could be best preserved. His plan was simple: regulate the banks and big businesses, and lower tariff rates to increase international trade, increasing competition in the interest of consumers. Wilson took the unusual step of calling a special session of Congress in April 1913 to tackle the tariff question, which resulted in the Revenue Act of 1913, also known as the Underwood Tariff Act. This legislation lowered tariff rates across the board by approximately 15 percent and completely eliminated tariffs on several imports, including steel, iron ore, woolen products, and farm tools. To offset the potential loss of federal revenue, this new law reinstituted the federal income tax, which followed the ratification of the Sixteenth Amendment. This first income tax required married couples who earned $4000 or more, and single people who earned $3000 or more, to pay a 1-percent, graduated income tax, with the tax rate getting progressively higher for those who earned more. Late in 1913, Wilson signed the Federal Reserve Act to regulate the banking industry and establish a federal banking system ( Figure 21.22 ). Designed to remove power over interest rates from the hands of private bankers, the new system created twelve privately owned regional reserve banks regulated by a presidentially appointed Federal Reserve Board. The Board, known informally as the Fed, regulated the interest rate at which reserve banks loaned or distributed money to other banks around the country. Thus, when economic times were challenging, such as during a recession, the Fed could lower this “discount rate” and encourage more borrowing, which put more currency in circulation for people to spend or invest. Conversely, the Fed could curb inflationary trends with interest hikes that discouraged borrowing. This system is still the basis for the country’s modern banking model. In early 1914, Wilson completed his New Freedom agenda with the passage of the Clayton Antitrust Act. This law expanded the power of the original Sherman Antitrust Act in order to allow the investigation and dismantling of more monopolies. The new act also took on the “interlocking directorates”—competing companies that still operated together in a form of oligopoly or conspiracy to restrain trade. His New Freedom agenda complete, Wilson turned his attention to foreign affairs, as war was quickly encompassing Europe. THE FINAL VESTIGES OF PROGRESSIVISM As the 1916 election approached, Wilson’s focus on foreign affairs, as well as the natural effect of his small government agenda, left the 60 percent of the American public who had not voted for him the first time disinclined to change their minds and keep him in office. Realizing this, Wilson began a flurry of new Progressive reforms that impressed the voting public and ultimately proved to be the last wave of the Progressive Era. Some of the important measures that Wilson undertook to pass included the Federal Farm Act, which provided oversight of low-interest loans to millions of farmers in need of debt relief; the Keating-Owen Child Labor Act, which, although later deemed unconstitutional by the U.S. Supreme Court, prohibited the interstate distribution of products by child workers under the age of fourteen; and the Adamson Act, which put in place the first federally mandated eight-hour workday for railroad workers. Wilson also gained significant support from Jewish voters with his 1916 appointment of the first Jewish U.S. Supreme Court justice, Louis D. Brandeis. Popular among social justice Progressives, Brandeis went on to become one of the most renowned justices on the court for his defense of freedom of speech and right to privacy issues. Finally, Wilson gained the support of many working-class voters with his defense of labor and union rights during a violent coal strike in Ludlow, Colorado, as well as his actions to forestall a potential railroad strike with the passage of the aforementioned Adamson Act. Wilson’s actions in 1916 proved enough, but barely. In a close presidential election, he secured a second term by defeating former New York governor Charles Evans Hughes by a scant twenty-three electoral votes, and less than 600,000 popular votes. Influential states like Minnesota and New Hampshire were decided by less than four hundred votes. Despite the fact that he ran for reelection with the slogan, “He Kept Us Out of the War,” Wilson could not avoid the reach of World War I much longer. For Wilson and the American public, the Progressive Era was rapidly winding down. Although a few Progressive achievements were still to come in the areas of women’s suffrage and prohibition, the country would soon be gripped by the war that Wilson had tried to avoid during his first term in office. When he took the oath for his second term, on March 4, 1917, Wilson was barely five weeks away from leading the United States in declaring war on Germany, a move that would put an end to the Progressive Era.
anatomy_and_physiology
Chapter Objectives After studying this chapter, you will be able to: List and explain the steps involved in fertilization Describe the major events in embryonic development Describe the major events in fetal development Discuss the adaptations of a woman’s body to pregnancy Describe the physiologic adjustments that the newborn must make in the first hours of extrauterine life Summarize the physiology of lactation Classify and describe the different patterns of inheritance Introduction In approximately nine months, a single cell—a fertilized egg—develops into a fully formed infant consisting of trillions of cells with myriad specialized functions. The dramatic changes of fertilization, embryonic development, and fetal development are followed by remarkable adaptations of the newborn to life outside the womb. An offspring’s normal development depends upon the appropriate synthesis of structural and functional proteins. This, in turn, is governed by the genetic material inherited from the parental egg and sperm, as well as environmental factors.
[ { "answer": { "ans_choice": 0, "ans_text": "most do not reach the oocyte" }, "bloom": "1", "hl_context": "Fertilization is a numbers game . <hl> During ejaculation , hundreds of millions of sperm ( spermatozoa ) are released into the vagina . <hl> <hl> Almost immediately , millions of these sperm are overcome by the acidity of the vagina ( approximately pH 3.8 ) , and millions more may be blocked from entering the uterus by thick cervical mucus . <hl> <hl> Of those that do enter , thousands are destroyed by phagocytic uterine leukocytes . <hl> <hl> Thus , the race into the uterine tubes , which is the most typical site for sperm to encounter the oocyte , is reduced to a few thousand contenders . <hl> Their journey — thought to be facilitated by uterine contractions — usually takes from 30 minutes to 2 hours . If the sperm do not encounter an oocyte immediately , they can survive in the uterine tubes for another 3 – 5 days . Thus , fertilization can still occur if intercourse takes place a few days before ovulation . In comparison , an oocyte can survive independently for only approximately 24 hours following ovulation . Intercourse more than a day after ovulation will therefore usually not result in fertilization .", "hl_sentences": "During ejaculation , hundreds of millions of sperm ( spermatozoa ) are released into the vagina . Almost immediately , millions of these sperm are overcome by the acidity of the vagina ( approximately pH 3.8 ) , and millions more may be blocked from entering the uterus by thick cervical mucus . Of those that do enter , thousands are destroyed by phagocytic uterine leukocytes . Thus , the race into the uterine tubes , which is the most typical site for sperm to encounter the oocyte , is reduced to a few thousand contenders .", "question": { "cloze_format": "Although the male ejaculate contains hundreds of millions of sperm, ________.", "normal_format": "Which of the following is true, although the male ejaculate contains hundreds of millions of sperm?", "question_choices": [ "most do not reach the oocyte", "most are destroyed by the alkaline environment of the uterus", "it takes millions to penetrate the outer layers of the oocyte", "most are destroyed by capacitation" ], "question_id": "fs-id1407729", "question_text": "Although the male ejaculate contains hundreds of millions of sperm, ________." }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 1, "ans_text": "corona radiata" }, "bloom": "1", "hl_context": "As it is swept along the distal uterine tube , the oocyte encounters the surviving capacitated sperm , which stream toward it in response to chemical attractants released by the cells of the corona radiata . <hl> To reach the oocyte itself , the sperm must penetrate the two protective layers . <hl> <hl> The sperm first burrow through the cells of the corona radiata . <hl> Then , upon contact with the zona pellucida , the sperm bind to receptors in the zona pellucida . This initiates a process called the acrosomal reaction in which the enzyme-filled “ cap ” of the sperm , called the acrosome , releases its stored digestive enzymes . These enzymes clear a path through the zona pellucida that allows sperm to reach the oocyte . Finally , a single sperm makes contact with sperm-binding receptors on the oocyte ’ s plasma membrane ( Figure 28.2 ) . The plasma membrane of that sperm then fuses with the oocyte ’ s plasma membrane , and the head and mid-piece of the “ winning ” sperm enter the oocyte interior .", "hl_sentences": "To reach the oocyte itself , the sperm must penetrate the two protective layers . The sperm first burrow through the cells of the corona radiata .", "question": { "cloze_format": "As sperm first reach the oocyte, they will contact the ________.", "normal_format": "As sperm first reach the oocyte, which will they contact?", "question_choices": [ "acrosome", "corona radiata", "sperm-binding receptors", "zona pellucida" ], "question_id": "fs-id2346687", "question_text": "As sperm first reach the oocyte, they will contact the ________." }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 2, "ans_text": "fertilization" }, "bloom": "1", "hl_context": "Recall that at the point of fertilization , the oocyte has not yet completed meiosis ; all secondary oocytes remain arrested in metaphase of meiosis II until fertilization . Only upon fertilization does the oocyte complete meiosis . The unneeded complement of genetic material that results is stored in a second polar body that is eventually ejected . At this moment , the oocyte has become an ovum , the female haploid gamete . The two haploid nuclei derived from the sperm and oocyte and contained within the egg are referred to as pronuclei . They decondense , expand , and replicate their DNA in preparation for mitosis . <hl> The pronuclei then migrate toward each other , their nuclear envelopes disintegrate , and the male - and female-derived genetic material intermingles . <hl> <hl> This step completes the process of fertilization and results in a single-celled diploid zygote with all the genetic instructions it needs to develop into a human . <hl>", "hl_sentences": "The pronuclei then migrate toward each other , their nuclear envelopes disintegrate , and the male - and female-derived genetic material intermingles . This step completes the process of fertilization and results in a single-celled diploid zygote with all the genetic instructions it needs to develop into a human .", "question": { "cloze_format": "Fusion of pronuclei occurs during ________.", "normal_format": "During which of the following fusion of pronuclei occurs?", "question_choices": [ "spermatogenesis", "ovulation", "fertilization", "capacitation" ], "question_id": "fs-id1288730", "question_text": "Fusion of pronuclei occurs during ________." }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 0, "ans_text": "capacitation" }, "bloom": "1", "hl_context": "During the journey , fluids in the female reproductive tract prepare the sperm for fertilization through a process called capacitation , or priming . The fluids improve the motility of the spermatozoa . They also deplete cholesterol molecules embedded in the membrane of the head of the sperm , thinning the membrane in such a way that will help facilitate the release of the lysosomal ( digestive ) enzymes needed for the sperm to penetrate the oocyte ’ s exterior once contact is made . <hl> Sperm must undergo the process of capacitation in order to have the “ capacity ” to fertilize an oocyte . <hl> If they reach the oocyte before capacitation is complete , they will be unable to penetrate the oocyte ’ s thick outer layer of cells .", "hl_sentences": "Sperm must undergo the process of capacitation in order to have the “ capacity ” to fertilize an oocyte .", "question": { "cloze_format": "Sperm must first complete ________ to enable the fertilization of an oocyte.", "normal_format": "What must sperm first complete to enable the fertilization of an oocyte?", "question_choices": [ "capacitation", "the acrosomal reaction", "the cortical reaction", "the fast block" ], "question_id": "fs-id2111179", "question_text": "Sperm must first complete ________ to enable the fertilization of an oocyte." }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 3, "ans_text": "blastomeres" }, "bloom": "1", "hl_context": "Following fertilization , the zygote and its associated membranes , together referred to as the conceptus , continue to be projected toward the uterus by peristalsis and beating cilia of the epithelial cells of the Fallopian tube . During its journey to the uterus , the zygote undergoes five or six rapid mitotic cell divisions . Although each cleavage results in more cells , it does not increase the total volume of the conceptus ( Figure 28.4 ) . <hl> Each daughter cell produced by cleavage is called a blastomere ( blastos = “ germ , ” in the sense of a seed or sprout ) . <hl>", "hl_sentences": "Each daughter cell produced by cleavage is called a blastomere ( blastos = “ germ , ” in the sense of a seed or sprout ) .", "question": { "cloze_format": "Cleavage produces daughter cells called ________.", "normal_format": "What are cleavage produces daughter cells?", "question_choices": [ "trophoblasts", "blastocysts", "morulae", "blastomeres" ], "question_id": "fs-id2282515", "question_text": "Cleavage produces daughter cells called ________." }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 1, "ans_text": "divides" }, "bloom": null, "hl_context": "Approximately 3 days after fertilization , a 16 - cell conceptus reaches the uterus . The cells that had been loosely grouped are now compacted and look more like a solid mass . The name given to this structure is the morula ( morula = “ little mulberry ” ) . <hl> Once inside the uterus , the conceptus floats freely for several more days . <hl> <hl> It continues to divide , creating a ball of approximately 100 cells , and consuming nutritive endometrial secretions called uterine milk while the uterine lining thickens . <hl> The ball of now tightly bound cells starts to secrete fluid and organize themselves around a fluid-filled cavity , the blastocoel . At this developmental stage , the conceptus is referred to as a blastocyst . Within this structure , a group of cells forms into an inner cell mass , which is fated to become the embryo . The cells that form the outer shell are called trophoblasts ( trophe = “ to feed ” or “ to nourish ” ) . These cells will develop into the chorionic sac and the fetal portion of the placenta ( the organ of nutrient , waste , and gas exchange between mother and the developing offspring ) .", "hl_sentences": "Once inside the uterus , the conceptus floats freely for several more days . It continues to divide , creating a ball of approximately 100 cells , and consuming nutritive endometrial secretions called uterine milk while the uterine lining thickens .", "question": { "cloze_format": "The conceptus, upon reaching the uterus, first ________.", "normal_format": "What does the conceptus, upon reaching the uterus, do first?", "question_choices": [ "implants", "divides", "disintegrates", "hatches" ], "question_id": "fs-id2483344", "question_text": "The conceptus, upon reaching the uterus, first ________." }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 0, "ans_text": "embryo" }, "bloom": null, "hl_context": "Approximately 3 days after fertilization , a 16 - cell conceptus reaches the uterus . The cells that had been loosely grouped are now compacted and look more like a solid mass . The name given to this structure is the morula ( morula = “ little mulberry ” ) . Once inside the uterus , the conceptus floats freely for several more days . It continues to divide , creating a ball of approximately 100 cells , and consuming nutritive endometrial secretions called uterine milk while the uterine lining thickens . The ball of now tightly bound cells starts to secrete fluid and organize themselves around a fluid-filled cavity , the blastocoel . <hl> At this developmental stage , the conceptus is referred to as a blastocyst . <hl> <hl> Within this structure , a group of cells forms into an inner cell mass , which is fated to become the embryo . <hl> The cells that form the outer shell are called trophoblasts ( trophe = “ to feed ” or “ to nourish ” ) . These cells will develop into the chorionic sac and the fetal portion of the placenta ( the organ of nutrient , waste , and gas exchange between mother and the developing offspring ) .", "hl_sentences": "At this developmental stage , the conceptus is referred to as a blastocyst . Within this structure , a group of cells forms into an inner cell mass , which is fated to become the embryo .", "question": { "cloze_format": "The inner cell mass of the blastocyst is destined to become the ________.", "normal_format": "What is the inner cell mass of the blastocyst destined to become?", "question_choices": [ "embryo", "trophoblast", "chorionic villi", "placenta" ], "question_id": "fs-id2521627", "question_text": "The inner cell mass of the blastocyst is destined to become the ________." }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 1, "ans_text": "ectoderm" }, "bloom": "1", "hl_context": "Each of these germ layers will develop into specific structures in the embryo . Whereas the ectoderm and endoderm form tightly connected epithelial sheets , the mesodermal cells are less organized and exist as a loosely connected cell community . <hl> The ectoderm gives rise to cell lineages that differentiate to become the central and peripheral nervous systems , sensory organs , epidermis , hair , and nails . <hl> Mesodermal cells ultimately become the skeleton , muscles , connective tissue , heart , blood vessels , and kidneys . The endoderm goes on to form the epithelial lining of the gastrointestinal tract , liver , and pancreas , as well as the lungs ( Figure 28.10 ) .", "hl_sentences": "The ectoderm gives rise to cell lineages that differentiate to become the central and peripheral nervous systems , sensory organs , epidermis , hair , and nails .", "question": { "cloze_format": "The primary germ layer that gave rise to the cells that eventually became the central nervous system is the ___.", "normal_format": "Which primary germ layer gave rise to the cells that eventually became the central nervous system?", "question_choices": [ "endoderm", "ectoderm", "acrosome", "mesoderm" ], "question_id": "fs-id2569816", "question_text": "Which primary germ layer gave rise to the cells that eventually became the central nervous system?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 2, "ans_text": "Menses would flush the blastocyst out of the uterus." }, "bloom": "3", "hl_context": "When implantation succeeds and the blastocyst adheres to the endometrium , the superficial cells of the trophoblast fuse with each other , forming the syncytiotrophoblast , a multinucleated body that digests endometrial cells to firmly secure the blastocyst to the uterine wall . In response , the uterine mucosa rebuilds itself and envelops the blastocyst ( Figure 28.6 ) . <hl> The trophoblast secretes human chorionic gonadotropin ( hCG ) , a hormone that directs the corpus luteum to survive , enlarge , and continue producing progesterone and estrogen to suppress menses . <hl> These functions of hCG are necessary for creating an environment suitable for the developing embryo . As a result of this increased production , hCG accumulates in the maternal bloodstream and is excreted in the urine . Implantation is complete by the middle of the second week . Just a few days after implantation , the trophoblast has secreted enough hCG for an at-home urine pregnancy test to give a positive result . At the end of the first week , the blastocyst comes in contact with the uterine wall and adheres to it , embedding itself in the uterine lining via the trophoblast cells . Thus begins the process of implantation , which signals the end of the pre-embryonic stage of development ( Figure 28.5 ) . Implantation can be accompanied by minor bleeding . The blastocyst typically implants in the fundus of the uterus or on the posterior wall . However , if the endometrium is not fully developed and ready to receive the blastocyst , the blastocyst will detach and find a better spot . <hl> A significant percentage ( 50 – 75 percent ) of blastocysts fail to implant ; when this occurs , the blastocyst is shed with the endometrium during menses . <hl> The high rate of implantation failure is one reason why pregnancy typically requires several ovulation cycles to achieve .", "hl_sentences": "The trophoblast secretes human chorionic gonadotropin ( hCG ) , a hormone that directs the corpus luteum to survive , enlarge , and continue producing progesterone and estrogen to suppress menses . A significant percentage ( 50 – 75 percent ) of blastocysts fail to implant ; when this occurs , the blastocyst is shed with the endometrium during menses .", "question": { "cloze_format": "If the trophoblast did not secrete hCG upon implantation of the blastocyst ___.", "normal_format": "What would happen if the trophoblast did not secrete hCG upon implantation of the blastocyst?", "question_choices": [ "The cells would not continue to divide.", "The corpus luteum would continue to produce progesterone and estrogen.", "Menses would flush the blastocyst out of the uterus.", "The uterine mucosa would not envelop the blastocyst." ], "question_id": "fs-id2325889", "question_text": "What would happen if the trophoblast did not secrete hCG upon implantation of the blastocyst?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 0, "ans_text": "embryonic folding" }, "bloom": "1", "hl_context": "<hl> The embryo , which begins as a flat sheet of cells , begins to acquire a cylindrical shape through the process of embryonic folding ( Figure 28.14 ) . <hl> The embryo folds laterally and again at either end , forming a C-shape with distinct head and tail ends . The embryo envelops a portion of the yolk sac , which protrudes with the umbilical cord from what will become the abdomen . The folding essentially creates a tube , called the primitive gut , that is lined by the endoderm . <hl> The amniotic sac , which was sitting on top of the flat embryo , envelops the embryo as it folds . <hl>", "hl_sentences": "The embryo , which begins as a flat sheet of cells , begins to acquire a cylindrical shape through the process of embryonic folding ( Figure 28.14 ) . The amniotic sac , which was sitting on top of the flat embryo , envelops the embryo as it folds .", "question": { "cloze_format": "The amnion envelops the embryo during the ___ process.", "normal_format": "During what process does the amnion envelop the embryo?", "question_choices": [ "embryonic folding", "gastrulation", "implantation", "organogenesis" ], "question_id": "fs-id2583932", "question_text": "During what process does the amnion envelop the embryo?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 2, "ans_text": "the mother’s endometrium and the embryo’s chorionic membrane" }, "bloom": "1", "hl_context": "<hl> The maternal portion of the placenta develops from the deepest layer of the endometrium , the decidua basalis . <hl> <hl> To form the embryonic portion of the placenta , the syncytiotrophoblast and the underlying cells of the trophoblast ( cytotrophoblast cells ) begin to proliferate along with a layer of extraembryonic mesoderm cells . <hl> <hl> These form the chorionic membrane , which envelops the entire conceptus as the chorion . <hl> <hl> The chorionic membrane forms finger-like structures called chorionic villi that burrow into the endometrium like tree roots , making up the fetal portion of the placenta . <hl> The cytotrophoblast cells perforate the chorionic villi , burrow farther into the endometrium , and remodel maternal blood vessels to augment maternal blood flow surrounding the villi . Meanwhile , fetal mesenchymal cells derived from the mesoderm fill the villi and differentiate into blood vessels , including the three umbilical blood vessels that connect the embryo to the developing placenta ( Figure 28.11 ) . During the first several weeks of development , the cells of the endometrium — referred to as decidual cells — nourish the nascent embryo . During prenatal weeks 4 – 12 , the developing placenta gradually takes over the role of feeding the embryo , and the decidual cells are no longer needed . <hl> The mature placenta is composed of tissues derived from the embryo , as well as maternal tissues of the endometrium . <hl> The placenta connects to the conceptus via the umbilical cord , which carries deoxygenated blood and wastes from the fetus through two umbilical arteries ; nutrients and oxygen are carried from the mother to the fetus through the single umbilical vein . The umbilical cord is surrounded by the amnion , and the spaces within the cord around the blood vessels are filled with Wharton ’ s jelly , a mucous connective tissue .", "hl_sentences": "The maternal portion of the placenta develops from the deepest layer of the endometrium , the decidua basalis . To form the embryonic portion of the placenta , the syncytiotrophoblast and the underlying cells of the trophoblast ( cytotrophoblast cells ) begin to proliferate along with a layer of extraembryonic mesoderm cells . These form the chorionic membrane , which envelops the entire conceptus as the chorion . The chorionic membrane forms finger-like structures called chorionic villi that burrow into the endometrium like tree roots , making up the fetal portion of the placenta . The mature placenta is composed of tissues derived from the embryo , as well as maternal tissues of the endometrium .", "question": { "cloze_format": "The placenta is formed from ________.", "normal_format": "From what is the placenta formed?", "question_choices": [ "the embryo’s mesenchymal cells", "the mother’s endometrium only", "the mother’s endometrium and the embryo’s chorionic membrane", "the mother’s endometrium and the embryo’s umbilical cord" ], "question_id": "fs-id2036445", "question_text": "The placenta is formed from ________." }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 1, "ans_text": "lungs" }, "bloom": "1", "hl_context": "Although the fetal liver is semifunctional , the fetal lungs are nonfunctional . <hl> The fetal circulation therefore bypasses the lungs by shifting some of the blood through the foramen ovale , a shunt that directly connects the right and left atria and avoids the pulmonary trunk altogether . <hl> Most of the rest of the blood is pumped to the right ventricle , and from there , into the pulmonary trunk , which splits into pulmonary arteries . However , a shunt within the pulmonary artery , the ductus arteriosus , diverts a portion of this blood into the aorta . This ensures that only a small volume of oxygenated blood passes through the immature pulmonary circuit , which has only minor metabolic requirements . Blood vessels of uninflated lungs have high resistance to flow , a condition that encourages blood to flow to the aorta , which presents much lower resistance . The oxygenated blood moves through the foramen ovale into the left atrium , where it mixes with the now deoxygenated blood returning from the pulmonary circuit . This blood then moves into the left ventricle , where it is pumped into the aorta . Some of this blood moves through the coronary arteries into the myocardium , and some moves through the carotid arteries to the brain .", "hl_sentences": "The fetal circulation therefore bypasses the lungs by shifting some of the blood through the foramen ovale , a shunt that directly connects the right and left atria and avoids the pulmonary trunk altogether .", "question": { "cloze_format": "The foramen ovale causes the fetal circulatory system to bypass the ________.", "normal_format": "The foramen ovale causes the fetal circulatory system to bypass what?", "question_choices": [ "liver", "lungs", "kidneys", "gonads" ], "question_id": "fs-id2294217", "question_text": "The foramen ovale causes the fetal circulatory system to bypass the ________." }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 2, "ans_text": "It adds to the amniotic fluid." }, "bloom": "1", "hl_context": "At the beginning of the second week , the cells of the inner cell mass form into a two-layered disc of embryonic cells , and a space — the amniotic cavity — opens up between it and the trophoblast ( Figure 28.8 ) . Cells from the upper layer of the disc ( the epiblast ) extend around the amniotic cavity , creating a membranous sac that forms into the amnion by the end of the second week . The amnion fills with amniotic fluid and eventually grows to surround the embryo . <hl> Early in development , amniotic fluid consists almost entirely of a filtrate of maternal plasma , but as the kidneys of the fetus begin to function at approximately the eighth week , they add urine to the volume of amniotic fluid . <hl> Floating within the amniotic fluid , the embryo — and later , the fetus — is protected from trauma and rapid temperature changes . It can move freely within the fluid and can prepare for swallowing and breathing out of the uterus .", "hl_sentences": "Early in development , amniotic fluid consists almost entirely of a filtrate of maternal plasma , but as the kidneys of the fetus begin to function at approximately the eighth week , they add urine to the volume of amniotic fluid .", "question": { "cloze_format": "When the kidneys begin to function, it happens to the urine excreted by the fetus that ___.", "normal_format": "What happens to the urine excreted by the fetus when the kidneys begin to function?", "question_choices": [ "The umbilical cord carries it to the placenta for removal.", "The endometrium absorbs it.", "It adds to the amniotic fluid.", "It is turned into meconium." ], "question_id": "fs-id2311187", "question_text": "What happens to the urine excreted by the fetus when the kidneys begin to function?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 0, "ans_text": "bone marrow begins to assume erythrocyte production" }, "bloom": "1", "hl_context": "<hl> Other Organ Systems During weeks 9 – 12 of fetal development , the brain continues to expand , the body elongates , and ossification continues . <hl> <hl> Fetal movements are frequent during this period , but are jerky and not well-controlled . <hl> <hl> The bone marrow begins to take over the process of erythrocyte production — a task that the liver performed during the embryonic period . <hl> The liver now secretes bile . The fetus circulates amniotic fluid by swallowing it and producing urine . The eyes are well-developed by this stage , but the eyelids are fused shut . The fingers and toes begin to develop nails . By the end of week 12 , the fetus measures approximately 9 cm ( 3.5 in ) from crown to rump . Weeks 13 – 16 are marked by sensory organ development . The eyes move closer together ; blinking motions begin , although the eyes remain sealed shut . The lips exhibit sucking motions . The ears move upward and lie flatter against the head . The scalp begins to grow hair . The excretory system is also developing : the kidneys are well-formed , and meconium , or fetal feces , begins to accumulate in the intestines . Meconium consists of ingested amniotic fluid , cellular debris , mucus , and bile .", "hl_sentences": "Other Organ Systems During weeks 9 – 12 of fetal development , the brain continues to expand , the body elongates , and ossification continues . Fetal movements are frequent during this period , but are jerky and not well-controlled . The bone marrow begins to take over the process of erythrocyte production — a task that the liver performed during the embryonic period .", "question": { "cloze_format": "During weeks 9–12 of fetal development, ________.", "normal_format": "What happens during weeks 9–12 of fetal development?", "question_choices": [ "bone marrow begins to assume erythrocyte production", "meconium begins to accumulate in the intestines", "surfactant production begins in the fetal lungs", "the spinal cord begins to be myelinated" ], "question_id": "fs-id1893042", "question_text": "During weeks 9–12 of fetal development, ________." }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 2, "ans_text": "FSH and LH" }, "bloom": "1", "hl_context": "<hl> The placenta takes over the synthesis and secretion of progesterone throughout pregnancy as the corpus luteum degenerates . <hl> <hl> Like estrogen , progesterone suppresses FSH and LH . <hl> It also inhibits uterine contractions , protecting the fetus from preterm birth . This hormone decreases in late gestation , allowing uterine contractions to intensify and eventually progress to true labor . The placenta also produces hCG . In addition to promoting survival of the corpus luteum , hCG stimulates the male fetal gonads to secrete testosterone , which is essential for the development of the male reproductive system .", "hl_sentences": "The placenta takes over the synthesis and secretion of progesterone throughout pregnancy as the corpus luteum degenerates . Like estrogen , progesterone suppresses FSH and LH .", "question": { "cloze_format": "Progesterone secreted by the placenta suppresses ________ to prevent maturation of ovarian follicles.", "normal_format": "What does Progesterone secreted by the placenta suppress to prevent maturation of ovarian follicles?", "question_choices": [ "LH and estrogen", "hCG and FSH", "FSH and LH", "estrogen and hCG" ], "question_id": "fs-id2102462", "question_text": "Progesterone secreted by the placenta suppresses ________ to prevent maturation of ovarian follicles." }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 1, "ans_text": "decreased intestinal peristalsis" }, "bloom": "1", "hl_context": "<hl> Nausea and vomiting , sometimes triggered by an increased sensitivity to odors , are common during the first few weeks to months of pregnancy . <hl> <hl> This phenomenon is often referred to as “ morning sickness , ” although the nausea may persist all day . <hl> The source of pregnancy nausea is thought to be the increased circulation of pregnancy-related hormones , specifically circulating estrogen , progesterone , and hCG . <hl> Decreased intestinal peristalsis may also contribute to nausea . <hl> By about week 12 of pregnancy , nausea typically subsides .", "hl_sentences": "Nausea and vomiting , sometimes triggered by an increased sensitivity to odors , are common during the first few weeks to months of pregnancy . This phenomenon is often referred to as “ morning sickness , ” although the nausea may persist all day . Decreased intestinal peristalsis may also contribute to nausea .", "question": { "cloze_format": "___ is a possible culprit of “morning sickness”.", "normal_format": "Which of the following is a possible culprit of “morning sickness”?", "question_choices": [ "increased minute respiration", "decreased intestinal peristalsis", "decreased aldosterone secretion", "increased blood volume" ], "question_id": "fs-id805292", "question_text": "Which of the following is a possible culprit of “morning sickness”?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 3, "ans_text": "decreasing the inhibition of uterine contractility" }, "bloom": "2", "hl_context": "<hl> First , recall that progesterone inhibits uterine contractions throughout the first several months of pregnancy . <hl> As the pregnancy enters its seventh month , progesterone levels plateau and then drop . Estrogen levels , however , continue to rise in the maternal circulation ( Figure 28.20 ) . The increasing ratio of estrogen to progesterone makes the myometrium ( the uterine smooth muscle ) more sensitive to stimuli that promote contractions ( because progesterone no longer inhibits them ) . Moreover , in the eighth month of pregnancy , fetal cortisol rises , which boosts estrogen secretion by the placenta and further overpowers the uterine-calming effects of progesterone . Some women may feel the result of the decreasing levels of progesterone in late pregnancy as weak and irregular peristaltic Braxton Hicks contractions , also called false labor . These contractions can often be relieved with rest or hydration . The placenta takes over the synthesis and secretion of progesterone throughout pregnancy as the corpus luteum degenerates . <hl> Like estrogen , progesterone suppresses FSH and LH . <hl> <hl> It also inhibits uterine contractions , protecting the fetus from preterm birth . <hl> <hl> This hormone decreases in late gestation , allowing uterine contractions to intensify and eventually progress to true labor . <hl> The placenta also produces hCG . In addition to promoting survival of the corpus luteum , hCG stimulates the male fetal gonads to secrete testosterone , which is essential for the development of the male reproductive system .", "hl_sentences": "First , recall that progesterone inhibits uterine contractions throughout the first several months of pregnancy . Like estrogen , progesterone suppresses FSH and LH . It also inhibits uterine contractions , protecting the fetus from preterm birth . This hormone decreases in late gestation , allowing uterine contractions to intensify and eventually progress to true labor .", "question": { "cloze_format": "The decrease in progesterone at the last weeks of pregnancy help to bring on labor by ___.", "normal_format": "How does the decrease in progesterone at the last weeks of pregnancy help to bring on labor?", "question_choices": [ "stimulating FSH production", "decreasing the levels of estrogens", "dilating the cervix", "decreasing the inhibition of uterine contractility" ], "question_id": "fs-id1978449", "question_text": "How does the decrease in progesterone at the last weeks of pregnancy help to bring on labor?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 3, "ans_text": "vertex occiput posterior" }, "bloom": null, "hl_context": "The expulsion stage begins when the fetal head enters the birth canal and ends with birth of the newborn . It typically takes up to 2 hours , but it can last longer or be completed in minutes , depending in part on the orientation of the fetus . <hl> The vertex presentation known as the occiput anterior vertex is the most common presentation and is associated with the greatest ease of vaginal birth . <hl> <hl> The fetus faces the maternal spinal cord and the smallest part of the head ( the posterior aspect called the occiput ) exits the birth canal first . <hl>", "hl_sentences": "The vertex presentation known as the occiput anterior vertex is the most common presentation and is associated with the greatest ease of vaginal birth . The fetus faces the maternal spinal cord and the smallest part of the head ( the posterior aspect called the occiput ) exits the birth canal first .", "question": { "cloze_format": "The fetal presentation that is the easiest for vaginal birth is a ___.", "normal_format": "Which of these fetal presentations is the easiest for vaginal birth?", "question_choices": [ "complete breech", "vertex occiput anterior", "frank breech", "vertex occiput posterior" ], "question_id": "fs-id1474295", "question_text": "Which of these fetal presentations is the easiest for vaginal birth?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 0, "ans_text": "foramen ovale" }, "bloom": "3", "hl_context": "Although the fetal liver is semifunctional , the fetal lungs are nonfunctional . <hl> The fetal circulation therefore bypasses the lungs by shifting some of the blood through the foramen ovale , a shunt that directly connects the right and left atria and avoids the pulmonary trunk altogether . <hl> Most of the rest of the blood is pumped to the right ventricle , and from there , into the pulmonary trunk , which splits into pulmonary arteries . However , a shunt within the pulmonary artery , the ductus arteriosus , diverts a portion of this blood into the aorta . This ensures that only a small volume of oxygenated blood passes through the immature pulmonary circuit , which has only minor metabolic requirements . Blood vessels of uninflated lungs have high resistance to flow , a condition that encourages blood to flow to the aorta , which presents much lower resistance . The oxygenated blood moves through the foramen ovale into the left atrium , where it mixes with the now deoxygenated blood returning from the pulmonary circuit . This blood then moves into the left ventricle , where it is pumped into the aorta . Some of this blood moves through the coronary arteries into the myocardium , and some moves through the carotid arteries to the brain .", "hl_sentences": "The fetal circulation therefore bypasses the lungs by shifting some of the blood through the foramen ovale , a shunt that directly connects the right and left atria and avoids the pulmonary trunk altogether .", "question": { "cloze_format": "The ___ shunt exists between the right and left atria.", "normal_format": "Which of these shunts exists between the right and left atria?", "question_choices": [ "foramen ovale", "ductus venosus", "ductus arteriosis", "foramen venosus" ], "question_id": "fs-id810682", "question_text": "Which of these shunts exists between the right and left atria?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 1, "ans_text": "It can be broken down to generate heat for thermoregulation." }, "bloom": "1", "hl_context": "<hl> The breakdown of brown fat occurs automatically upon exposure to cold , so it is an important heat regulator in newborns . <hl> During fetal development , the placenta secretes inhibitors that prevent metabolism of brown adipose fat and promote its accumulation in preparation for birth . <hl> Newborns , however , do have a special method for generating heat : nonshivering thermogenesis , which involves the breakdown of brown adipose tissue , or brown fat , which is distributed over the back , chest , and shoulders . <hl> Brown fat differs from the more familiar white fat in two ways :", "hl_sentences": "The breakdown of brown fat occurs automatically upon exposure to cold , so it is an important heat regulator in newborns . Newborns , however , do have a special method for generating heat : nonshivering thermogenesis , which involves the breakdown of brown adipose tissue , or brown fat , which is distributed over the back , chest , and shoulders .", "question": { "cloze_format": "Brown fat is important because ___ .", "normal_format": "Why is brown fat important?", "question_choices": [ "It is the newborn’s primary source of insulation.", "It can be broken down to generate heat for thermoregulation.", "It can be broken down for energy between feedings.", "It can be converted to white fat." ], "question_id": "fs-id1390282", "question_text": "Why is brown fat important?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 2, "ans_text": "elevates carbon dioxide levels in the blood" }, "bloom": "1", "hl_context": "Although the fetus “ practices ” breathing by inhaling amniotic fluid in utero , there is no air in the uterus and thus no true opportunity to breathe . ( There is also no need to breathe because the placenta supplies the fetus with all the oxygenated blood it needs . ) During gestation , the partially collapsed lungs are filled with amniotic fluid and exhibit very little metabolic activity . Several factors stimulate newborns to take their first breath at birth . <hl> First , labor contractions temporarily constrict umbilical blood vessels , reducing oxygenated blood flow to the fetus and elevating carbon dioxide levels in the blood . <hl> High carbon dioxide levels cause acidosis and stimulate the respiratory center in the brain , triggering the newborn to take a breath .", "hl_sentences": "First , labor contractions temporarily constrict umbilical blood vessels , reducing oxygenated blood flow to the fetus and elevating carbon dioxide levels in the blood .", "question": { "cloze_format": "Constriction of umbilical blood vessels during vaginal birth ________.", "normal_format": "Which of the following causes are true about constriction of umbilical blood vessels during vaginal birth?", "question_choices": [ "causes respiratory alkalosis", "inhibits the respiratory center in the brain", "elevates carbon dioxide levels in the blood", "both a and b" ], "question_id": "fs-id23202320", "question_text": "Constriction of umbilical blood vessels during vaginal birth ________." }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 1, "ans_text": "lactiferous ducts" }, "bloom": null, "hl_context": "Mammary glands are modified sweat glands . The non-pregnant and non-lactating female breast is composed primarily of adipose and collagenous tissue , with mammary glands making up a very minor proportion of breast volume . The mammary gland is composed of milk-transporting lactiferous ducts , which expand and branch extensively during pregnancy in response to estrogen , growth hormone , cortisol , and prolactin . Moreover , in response to progesterone , clusters of breast alveoli bud from the ducts and expand outward toward the chest wall . <hl> Breast alveoli are balloon-like structures lined with milk-secreting cuboidal cells , or lactocytes , that are surrounded by a net of contractile myoepithelial cells . <hl> Milk is secreted from the lactocytes , fills the alveoli , and is squeezed into the ducts . <hl> Clusters of alveoli that drain to a common duct are called lobules ; the lactating female has 12 – 20 lobules organized radially around the nipple . <hl> <hl> Milk drains from lactiferous ducts into lactiferous sinuses that meet at 4 to 18 perforations in the nipple , called nipple pores . <hl> The small bumps of the areola ( the darkened skin around the nipple ) are called Montgomery glands . They secrete oil to cleanse the nipple opening and prevent chapping and cracking of the nipple during breastfeeding .", "hl_sentences": "Breast alveoli are balloon-like structures lined with milk-secreting cuboidal cells , or lactocytes , that are surrounded by a net of contractile myoepithelial cells . Clusters of alveoli that drain to a common duct are called lobules ; the lactating female has 12 – 20 lobules organized radially around the nipple . Milk drains from lactiferous ducts into lactiferous sinuses that meet at 4 to 18 perforations in the nipple , called nipple pores .", "question": { "cloze_format": "Alveoli are connected to the lactiferous sinuses by ________.", "normal_format": "By what are alveol connected to the lactiferous sinuses?", "question_choices": [ "lactocytes", "lactiferous ducts", "nipple pores", "lobules" ], "question_id": "fs-id14839790", "question_text": "Alveoli are connected to the lactiferous sinuses by ________." }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 0, "ans_text": "It helps boost the newborn’s immune system." }, "bloom": "3", "hl_context": "Colostrum is secreted during the first 48 – 72 hours postpartum . Only a small volume of colostrum is produced — approximately 3 ounces in a 24 - hour period — but it is sufficient for the newborn in the first few days of life . <hl> Colostrum is rich with immunoglobulins , which confer gastrointestinal , and also likely systemic , immunity as the newborn adjusts to a nonsterile environment . <hl>", "hl_sentences": "Colostrum is rich with immunoglobulins , which confer gastrointestinal , and also likely systemic , immunity as the newborn adjusts to a nonsterile environment .", "question": { "cloze_format": "Colostrum is most important to a newborn because ___ .", "normal_format": "How is colostrum most important to a newborn?", "question_choices": [ "It helps boost the newborn’s immune system.", "It provides much needed fat.", "It satisfies the newborn’s thirst.", "It satisfies the infant’s appetite." ], "question_id": "fs-id2348104", "question_text": "How is colostrum most important to a newborn?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 3, "ans_text": "has more fat than cow’s milk" }, "bloom": "1", "hl_context": "<hl> After about the third postpartum day , the mother secretes transitional milk that represents an intermediate between mature milk and colostrum . <hl> This is followed by mature milk from approximately postpartum day 10 ( see Table 28.3 ) . <hl> As you can see in the accompanying table , cow ’ s milk is not a substitute for breast milk . <hl> <hl> It contains less lactose , less fat , and more protein and minerals . <hl> <hl> Moreover , the proteins in cow ’ s milk are difficult for an infant ’ s immature digestive system to metabolize and absorb . <hl>", "hl_sentences": "After about the third postpartum day , the mother secretes transitional milk that represents an intermediate between mature milk and colostrum . As you can see in the accompanying table , cow ’ s milk is not a substitute for breast milk . It contains less lactose , less fat , and more protein and minerals . Moreover , the proteins in cow ’ s milk are difficult for an infant ’ s immature digestive system to metabolize and absorb .", "question": { "cloze_format": "Mature breast milk ________.", "normal_format": "Which of the following is correct about mature breast milk?", "question_choices": [ "has more sodium than cow’s milk", "has more calcium than cow’s milk", "has more protein than cow’s milk", "has more fat than cow’s milk" ], "question_id": "fs-id2242284", "question_text": "Mature breast milk ________." }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 2, "ans_text": "multiple alleles" }, "bloom": "1", "hl_context": "In the simplest scenario , a single pair of genes will determine a single heritable characteristic . However , it is quite common for multiple genes to interact to confer a feature . For instance , eight or more genes — each with their own alleles — determine eye color in humans . <hl> Moreover , although any one person can only have two alleles corresponding to a given gene , more than two alleles commonly exist in a population . <hl> <hl> This phenomenon is called multiple alleles . <hl> <hl> For example , there are three different alleles that encode ABO blood type ; these are designated I A , I B , and i . <hl>", "hl_sentences": "Moreover , although any one person can only have two alleles corresponding to a given gene , more than two alleles commonly exist in a population . This phenomenon is called multiple alleles . For example , there are three different alleles that encode ABO blood type ; these are designated I A , I B , and i .", "question": { "cloze_format": "In addition to codominance, the ABO blood group antigens are also an example of ________.", "normal_format": "In addition to codominance, what are the ABO blood group antigens also an example of?", "question_choices": [ "incomplete dominance", "X-linked recessive inheritance", "multiple alleles", "recessive lethal inheritance" ], "question_id": "fs-id1340094", "question_text": "In addition to codominance, the ABO blood group antigens are also an example of ________." }, "references_are_paraphrase": null } ]
28
28.1 Fertilization Learning Objectives By the end of this section, you will be able to: Describe the obstacles that sperm must overcome to reach an oocyte Explain capacitation and its importance in fertilization Summarize the events that occur as a sperm fertilizes an oocyte Fertilization occurs when a sperm and an oocyte (egg) combine and their nuclei fuse. Because each of these reproductive cells is a haploid cell containing half of the genetic material needed to form a human being, their combination forms a diploid cell. This new single cell, called a zygote , contains all of the genetic material needed to form a human—half from the mother and half from the father. Transit of Sperm Fertilization is a numbers game. During ejaculation, hundreds of millions of sperm (spermatozoa) are released into the vagina. Almost immediately, millions of these sperm are overcome by the acidity of the vagina (approximately pH 3.8), and millions more may be blocked from entering the uterus by thick cervical mucus. Of those that do enter, thousands are destroyed by phagocytic uterine leukocytes. Thus, the race into the uterine tubes, which is the most typical site for sperm to encounter the oocyte, is reduced to a few thousand contenders. Their journey—thought to be facilitated by uterine contractions—usually takes from 30 minutes to 2 hours. If the sperm do not encounter an oocyte immediately, they can survive in the uterine tubes for another 3–5 days. Thus, fertilization can still occur if intercourse takes place a few days before ovulation. In comparison, an oocyte can survive independently for only approximately 24 hours following ovulation. Intercourse more than a day after ovulation will therefore usually not result in fertilization. During the journey, fluids in the female reproductive tract prepare the sperm for fertilization through a process called capacitation , or priming. The fluids improve the motility of the spermatozoa. They also deplete cholesterol molecules embedded in the membrane of the head of the sperm, thinning the membrane in such a way that will help facilitate the release of the lysosomal (digestive) enzymes needed for the sperm to penetrate the oocyte’s exterior once contact is made. Sperm must undergo the process of capacitation in order to have the “capacity” to fertilize an oocyte. If they reach the oocyte before capacitation is complete, they will be unable to penetrate the oocyte’s thick outer layer of cells. Contact Between Sperm and Oocyte Upon ovulation, the oocyte released by the ovary is swept into—and along—the uterine tube. Fertilization must occur in the distal uterine tube because an unfertilized oocyte cannot survive the 72-hour journey to the uterus. As you will recall from your study of the oogenesis, this oocyte (specifically a secondary oocyte) is surrounded by two protective layers. The corona radiata is an outer layer of follicular (granulosa) cells that form around a developing oocyte in the ovary and remain with it upon ovulation. The underlying zona pellucida (pellucid = “transparent”) is a transparent, but thick, glycoprotein membrane that surrounds the cell’s plasma membrane. As it is swept along the distal uterine tube, the oocyte encounters the surviving capacitated sperm, which stream toward it in response to chemical attractants released by the cells of the corona radiata. To reach the oocyte itself, the sperm must penetrate the two protective layers. The sperm first burrow through the cells of the corona radiata. Then, upon contact with the zona pellucida, the sperm bind to receptors in the zona pellucida. This initiates a process called the acrosomal reaction in which the enzyme-filled “cap” of the sperm, called the acrosome , releases its stored digestive enzymes. These enzymes clear a path through the zona pellucida that allows sperm to reach the oocyte. Finally, a single sperm makes contact with sperm-binding receptors on the oocyte’s plasma membrane ( Figure 28.2 ). The plasma membrane of that sperm then fuses with the oocyte’s plasma membrane, and the head and mid-piece of the “winning” sperm enter the oocyte interior. How do sperm penetrate the corona radiata? Some sperm undergo a spontaneous acrosomal reaction, which is an acrosomal reaction not triggered by contact with the zona pellucida. The digestive enzymes released by this reaction digest the extracellular matrix of the corona radiata. As you can see, the first sperm to reach the oocyte is never the one to fertilize it. Rather, hundreds of sperm cells must undergo the acrosomal reaction, each helping to degrade the corona radiata and zona pellucida until a path is created to allow one sperm to contact and fuse with the plasma membrane of the oocyte. If you consider the loss of millions of sperm between entry into the vagina and degradation of the zona pellucida, you can understand why a low sperm count can cause male infertility. When the first sperm fuses with the oocyte, the oocyte deploys two mechanisms to prevent polyspermy , which is penetration by more than one sperm. This is critical because if more than one sperm were to fertilize the oocyte, the resulting zygote would be a triploid organism with three sets of chromosomes. This is incompatible with life. The first mechanism is the fast block, which involves a near instantaneous change in sodium ion permeability upon binding of the first sperm, depolarizing the oocyte plasma membrane and preventing the fusion of additional sperm cells. The fast block sets in almost immediately and lasts for about a minute, during which time an influx of calcium ions following sperm penetration triggers the second mechanism, the slow block. In this process, referred to as the cortical reaction , cortical granules sitting immediately below the oocyte plasma membrane fuse with the membrane and release zonal inhibiting proteins and mucopolysaccharides into the space between the plasma membrane and the zona pellucida. Zonal inhibiting proteins cause the release of any other attached sperm and destroy the oocyte’s sperm receptors, thus preventing any more sperm from binding. The mucopolysaccharides then coat the nascent zygote in an impenetrable barrier that, together with hardened zona pellucida, is called a fertilization membrane . The Zygote Recall that at the point of fertilization, the oocyte has not yet completed meiosis; all secondary oocytes remain arrested in metaphase of meiosis II until fertilization. Only upon fertilization does the oocyte complete meiosis. The unneeded complement of genetic material that results is stored in a second polar body that is eventually ejected. At this moment, the oocyte has become an ovum, the female haploid gamete. The two haploid nuclei derived from the sperm and oocyte and contained within the egg are referred to as pronuclei. They decondense, expand, and replicate their DNA in preparation for mitosis. The pronuclei then migrate toward each other, their nuclear envelopes disintegrate, and the male- and female-derived genetic material intermingles. This step completes the process of fertilization and results in a single-celled diploid zygote with all the genetic instructions it needs to develop into a human. Most of the time, a woman releases a single egg during an ovulation cycle. However, in approximately 1 percent of ovulation cycles, two eggs are released and both are fertilized. Two zygotes form, implant, and develop, resulting in the birth of dizygotic (or fraternal) twins. Because dizygotic twins develop from two eggs fertilized by two sperm, they are no more identical than siblings born at different times. Much less commonly, a zygote can divide into two separate offspring during early development. This results in the birth of monozygotic (or identical) twins. Although the zygote can split as early as the two-cell stage, splitting occurs most commonly during the early blastocyst stage, with roughly 70–100 cells present. These two scenarios are distinct from each other, in that the twin embryos that separated at the two-cell stage will have individual placentas, whereas twin embryos that form from separation at the blastocyst stage will share a placenta and a chorionic cavity. Everyday Connection In Vitro Fertilization IVF, which stands for in vitro fertilization, is an assisted reproductive technology. In vitro, which in Latin translates to “in glass,” refers to a procedure that takes place outside of the body. There are many different indications for IVF. For example, a woman may produce normal eggs, but the eggs cannot reach the uterus because the uterine tubes are blocked or otherwise compromised. A man may have a low sperm count, low sperm motility, sperm with an unusually high percentage of morphological abnormalities, or sperm that are incapable of penetrating the zona pellucida of an egg. A typical IVF procedure begins with egg collection. A normal ovulation cycle produces only one oocyte, but the number can be boosted significantly (to 10–20 oocytes) by administering a short course of gonadotropins. The course begins with follicle-stimulating hormone (FSH) analogs, which support the development of multiple follicles, and ends with a luteinizing hormone (LH) analog that triggers ovulation. Right before the ova would be released from the ovary, they are harvested using ultrasound-guided oocyte retrieval. In this procedure, ultrasound allows a physician to visualize mature follicles. The ova are aspirated (sucked out) using a syringe. In parallel, sperm are obtained from the male partner or from a sperm bank. The sperm are prepared by washing to remove seminal fluid because seminal fluid contains a peptide, FPP (or, fertilization promoting peptide), that—in high concentrations—prevents capacitation of the sperm. The sperm sample is also concentrated, to increase the sperm count per milliliter. Next, the eggs and sperm are mixed in a petri dish. The ideal ratio is 75,000 sperm to one egg. If there are severe problems with the sperm—for example, the count is exceedingly low, or the sperm are completely nonmotile, or incapable of binding to or penetrating the zona pellucida—a sperm can be injected into an egg. This is called intracytoplasmic sperm injection (ICSI). The embryos are then incubated until they either reach the eight-cell stage or the blastocyst stage. In the United States, fertilized eggs are typically cultured to the blastocyst stage because this results in a higher pregnancy rate. Finally, the embryos are transferred to a woman’s uterus using a plastic catheter (tube). Figure 28.3 illustrates the steps involved in IVF. IVF is a relatively new and still evolving technology, and until recently it was necessary to transfer multiple embryos to achieve a good chance of a pregnancy. Today, however, transferred embryos are much more likely to implant successfully, so countries that regulate the IVF industry cap the number of embryos that can be transferred per cycle at two. This reduces the risk of multiple-birth pregnancies. The rate of success for IVF is correlated with a woman’s age. More than 40 percent of women under 35 succeed in giving birth following IVF, but the rate drops to a little over 10 percent in women over 40. Interactive Link Go to this site to view resources covering various aspects of fertilization, including movies and animations showing sperm structure and motility, ovulation, and fertilization. 28.2 Embryonic Development Learning Objectives By the end of this section, you will be able to: Distinguish the stages of embryonic development that occur before implantation Describe the process of implantation List and describe four embryonic membranes Explain gastrulation Describe how the placenta is formed and identify its functions Explain how an embryo transforms from a flat disc of cells into a three-dimensional shape resembling a human Summarize the process of organogenesis Throughout this chapter, we will express embryonic and fetal ages in terms of weeks from fertilization, commonly called conception. The period of time required for full development of a fetus in utero is referred to as gestation (gestare = “to carry” or “to bear”). It can be subdivided into distinct gestational periods. The first 2 weeks of prenatal development are referred to as the pre-embryonic stage. A developing human is referred to as an embryo during weeks 3–8, and a fetus from the ninth week of gestation until birth. In this section, we’ll cover the pre-embryonic and embryonic stages of development, which are characterized by cell division, migration, and differentiation. By the end of the embryonic period, all of the organ systems are structured in rudimentary form, although the organs themselves are either nonfunctional or only semi-functional. Pre-implantation Embryonic Development Following fertilization, the zygote and its associated membranes, together referred to as the conceptus , continue to be projected toward the uterus by peristalsis and beating cilia of the epithelial cells of the Fallopian tube. During its journey to the uterus, the zygote undergoes five or six rapid mitotic cell divisions. Although each cleavage results in more cells, it does not increase the total volume of the conceptus ( Figure 28.4 ). Each daughter cell produced by cleavage is called a blastomere (blastos = “germ,” in the sense of a seed or sprout). Approximately 3 days after fertilization, a 16-cell conceptus reaches the uterus. The cells that had been loosely grouped are now compacted and look more like a solid mass. The name given to this structure is the morula (morula = “little mulberry”). Once inside the uterus, the conceptus floats freely for several more days. It continues to divide, creating a ball of approximately 100 cells, and consuming nutritive endometrial secretions called uterine milk while the uterine lining thickens. The ball of now tightly bound cells starts to secrete fluid and organize themselves around a fluid-filled cavity, the blastocoel . At this developmental stage, the conceptus is referred to as a blastocyst . Within this structure, a group of cells forms into an inner cell mass , which is fated to become the embryo. The cells that form the outer shell are called trophoblasts (trophe = “to feed” or “to nourish”). These cells will develop into the chorionic sac and the fetal portion of the placenta (the organ of nutrient, waste, and gas exchange between mother and the developing offspring). The inner mass of embryonic cells is totipotent during this stage, meaning that each cell has the potential to differentiate into any cell type in the human body. Totipotency lasts for only a few days before the cells’ fates are set as being the precursors to a specific lineage of cells. As the blastocyst forms, the trophoblast excretes enzymes that begin to degrade the zona pellucida. In a process called “hatching,” the conceptus breaks free of the zona pellucida in preparation for implantation. Interactive Link View this time-lapse movie of a conceptus starting at day 3. What is the first structure you see? At what point in the movie does the blastocoel first appear? What event occurs at the end of the movie? Implantation At the end of the first week, the blastocyst comes in contact with the uterine wall and adheres to it, embedding itself in the uterine lining via the trophoblast cells. Thus begins the process of implantation , which signals the end of the pre-embryonic stage of development ( Figure 28.5 ). Implantation can be accompanied by minor bleeding. The blastocyst typically implants in the fundus of the uterus or on the posterior wall. However, if the endometrium is not fully developed and ready to receive the blastocyst, the blastocyst will detach and find a better spot. A significant percentage (50–75 percent) of blastocysts fail to implant; when this occurs, the blastocyst is shed with the endometrium during menses. The high rate of implantation failure is one reason why pregnancy typically requires several ovulation cycles to achieve. When implantation succeeds and the blastocyst adheres to the endometrium, the superficial cells of the trophoblast fuse with each other, forming the syncytiotrophoblast , a multinucleated body that digests endometrial cells to firmly secure the blastocyst to the uterine wall. In response, the uterine mucosa rebuilds itself and envelops the blastocyst ( Figure 28.6 ). The trophoblast secretes human chorionic gonadotropin (hCG) , a hormone that directs the corpus luteum to survive, enlarge, and continue producing progesterone and estrogen to suppress menses. These functions of hCG are necessary for creating an environment suitable for the developing embryo. As a result of this increased production, hCG accumulates in the maternal bloodstream and is excreted in the urine. Implantation is complete by the middle of the second week. Just a few days after implantation, the trophoblast has secreted enough hCG for an at-home urine pregnancy test to give a positive result. Most of the time an embryo implants within the body of the uterus in a location that can support growth and development. However, in one to two percent of cases, the embryo implants either outside the uterus (an ectopic pregnancy ) or in a region of uterus that can create complications for the pregnancy. If the embryo implants in the inferior portion of the uterus, the placenta can potentially grow over the opening of the cervix, a condition call placenta previa . Disorders of the... Development of the Embryo In the vast majority of ectopic pregnancies, the embryo does not complete its journey to the uterus and implants in the uterine tube, referred to as a tubal pregnancy. However, there are also ovarian ectopic pregnancies (in which the egg never left the ovary) and abdominal ectopic pregnancies (in which an egg was “lost” to the abdominal cavity during the transfer from ovary to uterine tube, or in which an embryo from a tubal pregnancy re-implanted in the abdomen). Once in the abdominal cavity, an embryo can implant into any well-vascularized structure—the rectouterine cavity (Douglas’ pouch), the mesentery of the intestines, and the greater omentum are some common sites. Tubal pregnancies can be caused by scar tissue within the tube following a sexually transmitted bacterial infection. The scar tissue impedes the progress of the embryo into the uterus—in some cases “snagging” the embryo and, in other cases, blocking the tube completely. Approximately one half of tubal pregnancies resolve spontaneously. Implantation in a uterine tube causes bleeding, which appears to stimulate smooth muscle contractions and expulsion of the embryo. In the remaining cases, medical or surgical intervention is necessary. If an ectopic pregnancy is detected early, the embryo’s development can be arrested by the administration of the cytotoxic drug methotrexate, which inhibits the metabolism of folic acid. If diagnosis is late and the uterine tube is already ruptured, surgical repair is essential. Even if the embryo has successfully found its way to the uterus, it does not always implant in an optimal location (the fundus or the posterior wall of the uterus). Placenta previa can result if an embryo implants close to the internal os of the uterus (the internal opening of the cervix). As the fetus grows, the placenta can partially or completely cover the opening of the cervix ( Figure 28.7 ). Although it occurs in only 0.5 percent of pregnancies, placenta previa is the leading cause of antepartum hemorrhage (profuse vaginal bleeding after week 24 of pregnancy but prior to childbirth). Embryonic Membranes During the second week of development, with the embryo implanted in the uterus, cells within the blastocyst start to organize into layers. Some grow to form the extra-embryonic membranes needed to support and protect the growing embryo: the amnion, the yolk sac, the allantois, and the chorion. At the beginning of the second week, the cells of the inner cell mass form into a two-layered disc of embryonic cells, and a space—the amniotic cavity —opens up between it and the trophoblast ( Figure 28.8 ). Cells from the upper layer of the disc (the epiblast ) extend around the amniotic cavity, creating a membranous sac that forms into the amnion by the end of the second week. The amnion fills with amniotic fluid and eventually grows to surround the embryo. Early in development, amniotic fluid consists almost entirely of a filtrate of maternal plasma, but as the kidneys of the fetus begin to function at approximately the eighth week, they add urine to the volume of amniotic fluid. Floating within the amniotic fluid, the embryo—and later, the fetus—is protected from trauma and rapid temperature changes. It can move freely within the fluid and can prepare for swallowing and breathing out of the uterus. On the ventral side of the embryonic disc, opposite the amnion, cells in the lower layer of the embryonic disk (the hypoblast ) extend into the blastocyst cavity and form a yolk sac . The yolk sac supplies some nutrients absorbed from the trophoblast and also provides primitive blood circulation to the developing embryo for the second and third week of development. When the placenta takes over nourishing the embryo at approximately week 4, the yolk sac has been greatly reduced in size and its main function is to serve as the source of blood cells and germ cells (cells that will give rise to gametes). During week 3, a finger-like outpocketing of the yolk sac develops into the allantois , a primitive excretory duct of the embryo that will become part of the urinary bladder. Together, the stalks of the yolk sac and allantois establish the outer structure of the umbilical cord. The last of the extra-embryonic membranes is the chorion , which is the one membrane that surrounds all others. The development of the chorion will be discussed in more detail shortly, as it relates to the growth and development of the placenta. Embryogenesis As the third week of development begins, the two-layered disc of cells becomes a three-layered disc through the process of gastrulation , during which the cells transition from totipotency to multipotency. The embryo, which takes the shape of an oval-shaped disc, forms an indentation called the primitive streak along the dorsal surface of the epiblast. A node at the caudal or “tail” end of the primitive streak emits growth factors that direct cells to multiply and migrate. Cells migrate toward and through the primitive streak and then move laterally to create two new layers of cells. The first layer is the endoderm , a sheet of cells that displaces the hypoblast and lies adjacent to the yolk sac. The second layer of cells fills in as the middle layer, or mesoderm . The cells of the epiblast that remain (not having migrated through the primitive streak) become the ectoderm ( Figure 28.9 ). Each of these germ layers will develop into specific structures in the embryo. Whereas the ectoderm and endoderm form tightly connected epithelial sheets, the mesodermal cells are less organized and exist as a loosely connected cell community. The ectoderm gives rise to cell lineages that differentiate to become the central and peripheral nervous systems, sensory organs, epidermis, hair, and nails. Mesodermal cells ultimately become the skeleton, muscles, connective tissue, heart, blood vessels, and kidneys. The endoderm goes on to form the epithelial lining of the gastrointestinal tract, liver, and pancreas, as well as the lungs ( Figure 28.10 ). Development of the Placenta During the first several weeks of development, the cells of the endometrium—referred to as decidual cells—nourish the nascent embryo. During prenatal weeks 4–12, the developing placenta gradually takes over the role of feeding the embryo, and the decidual cells are no longer needed. The mature placenta is composed of tissues derived from the embryo, as well as maternal tissues of the endometrium. The placenta connects to the conceptus via the umbilical cord , which carries deoxygenated blood and wastes from the fetus through two umbilical arteries; nutrients and oxygen are carried from the mother to the fetus through the single umbilical vein. The umbilical cord is surrounded by the amnion, and the spaces within the cord around the blood vessels are filled with Wharton’s jelly, a mucous connective tissue. The maternal portion of the placenta develops from the deepest layer of the endometrium, the decidua basalis. To form the embryonic portion of the placenta, the syncytiotrophoblast and the underlying cells of the trophoblast (cytotrophoblast cells) begin to proliferate along with a layer of extraembryonic mesoderm cells. These form the chorionic membrane , which envelops the entire conceptus as the chorion. The chorionic membrane forms finger-like structures called chorionic villi that burrow into the endometrium like tree roots, making up the fetal portion of the placenta. The cytotrophoblast cells perforate the chorionic villi, burrow farther into the endometrium, and remodel maternal blood vessels to augment maternal blood flow surrounding the villi. Meanwhile, fetal mesenchymal cells derived from the mesoderm fill the villi and differentiate into blood vessels, including the three umbilical blood vessels that connect the embryo to the developing placenta ( Figure 28.11 ). The placenta develops throughout the embryonic period and during the first several weeks of the fetal period; placentation is complete by weeks 14–16. As a fully developed organ, the placenta provides nutrition and excretion, respiration, and endocrine function ( Table 28.1 and Figure 28.12 ). It receives blood from the fetus through the umbilical arteries. Capillaries in the chorionic villi filter fetal wastes out of the blood and return clean, oxygenated blood to the fetus through the umbilical vein. Nutrients and oxygen are transferred from maternal blood surrounding the villi through the capillaries and into the fetal bloodstream. Some substances move across the placenta by simple diffusion. Oxygen, carbon dioxide, and any other lipid-soluble substances take this route. Other substances move across by facilitated diffusion. This includes water-soluble glucose. The fetus has a high demand for amino acids and iron, and those substances are moved across the placenta by active transport. Maternal and fetal blood does not commingle because blood cells cannot move across the placenta. This separation prevents the mother’s cytotoxic T cells from reaching and subsequently destroying the fetus, which bears “non-self” antigens. Further, it ensures the fetal red blood cells do not enter the mother’s circulation and trigger antibody development (if they carry “non-self” antigens)—at least until the final stages of pregnancy or birth. This is the reason that, even in the absence of preventive treatment, an Rh − mother doesn’t develop antibodies that could cause hemolytic disease in her first Rh + fetus. Although blood cells are not exchanged, the chorionic villi provide ample surface area for the two-way exchange of substances between maternal and fetal blood. The rate of exchange increases throughout gestation as the villi become thinner and increasingly branched. The placenta is permeable to lipid-soluble fetotoxic substances: alcohol, nicotine, barbiturates, antibiotics, certain pathogens, and many other substances that can be dangerous or fatal to the developing embryo or fetus. For these reasons, pregnant women should avoid fetotoxic substances. Alcohol consumption by pregnant women, for example, can result in a range of abnormalities referred to as fetal alcohol spectrum disorders (FASD). These include organ and facial malformations, as well as cognitive and behavioral disorders. Functions of the Placenta Nutrition and digestion Respiration Endocrine function Mediates diffusion of maternal glucose, amino acids, fatty acids, vitamins, and minerals Stores nutrients during early pregnancy to accommodate increased fetal demand later in pregnancy Excretes and filters fetal nitrogenous wastes into maternal blood Mediates maternal-to-fetal oxygen transport and fetal-to-maternal carbon dioxide transport Secretes several hormones, including hCG, estrogens, and progesterone, to maintain the pregnancy and stimulate maternal and fetal development Mediates the transmission of maternal hormones into fetal blood and vice versa Table 28.1 Organogenesis Following gastrulation, rudiments of the central nervous system develop from the ectoderm in the process of neurulation ( Figure 28.13 ). Specialized neuroectodermal tissues along the length of the embryo thicken into the neural plate . During the fourth week, tissues on either side of the plate fold upward into a neural fold . The two folds converge to form the neural tube . The tube lies atop a rod-shaped, mesoderm-derived notochord , which eventually becomes the nucleus pulposus of intervertebral discs. Block-like structures called somites form on either side of the tube, eventually differentiating into the axial skeleton, skeletal muscle, and dermis. During the fourth and fifth weeks, the anterior neural tube dilates and subdivides to form vesicles that will become the brain structures. Folate, one of the B vitamins, is important to the healthy development of the neural tube. A deficiency of maternal folate in the first weeks of pregnancy can result in neural tube defects, including spina bifida—a birth defect in which spinal tissue protrudes through the newborn’s vertebral column, which has failed to completely close. A more severe neural tube defect is anencephaly, a partial or complete absence of brain tissue. The embryo, which begins as a flat sheet of cells, begins to acquire a cylindrical shape through the process of embryonic folding ( Figure 28.14 ). The embryo folds laterally and again at either end, forming a C-shape with distinct head and tail ends. The embryo envelops a portion of the yolk sac, which protrudes with the umbilical cord from what will become the abdomen. The folding essentially creates a tube, called the primitive gut, that is lined by the endoderm. The amniotic sac, which was sitting on top of the flat embryo, envelops the embryo as it folds. Within the first 8 weeks of gestation, a developing embryo establishes the rudimentary structures of all of its organs and tissues from the ectoderm, mesoderm, and endoderm. This process is called organogenesis . Like the central nervous system, the heart also begins its development in the embryo as a tube-like structure, connected via capillaries to the chorionic villi. Cells of the primitive tube-shaped heart are capable of electrical conduction and contraction. The heart begins beating in the beginning of the fourth week, although it does not actually pump embryonic blood until a week later, when the oversized liver has begun producing red blood cells. (This is a temporary responsibility of the embryonic liver that the bone marrow will assume during fetal development.) During weeks 4–5, the eye pits form, limb buds become apparent, and the rudiments of the pulmonary system are formed. During the sixth week, uncontrolled fetal limb movements begin to occur. The gastrointestinal system develops too rapidly for the embryonic abdomen to accommodate it, and the intestines temporarily loop into the umbilical cord. Paddle-shaped hands and feet develop fingers and toes by the process of apoptosis (programmed cell death), which causes the tissues between the fingers to disintegrate. By week 7, the facial structure is more complex and includes nostrils, outer ears, and lenses ( Figure 28.15 ). By the eighth week, the head is nearly as large as the rest of the embryo’s body, and all major brain structures are in place. The external genitalia are apparent, but at this point, male and female embryos are indistinguishable. Bone begins to replace cartilage in the embryonic skeleton through the process of ossification. By the end of the embryonic period, the embryo is approximately 3 cm (1.2 in) from crown to rump and weighs approximately 8 g (0.25 oz). Interactive Link Use this interactive tool to view the process of embryogenesis from fertilization through pregnancy to birth. Can you identify when neurulation occurs in the embryo? 28.3 Fetal Development Learning Objectives By the end of this section, you will be able to: Differentiate between the embryonic period and the fetal period Briefly describe the process of sexual differentiation Describe the fetal circulatory system and explain the role of the shunts Trace the development of a fetus from the end of the embryonic period to birth As you will recall, a developing human is called a fetus from the ninth week of gestation until birth. This 30-week period of development is marked by continued cell growth and differentiation, which fully develop the structures and functions of the immature organ systems formed during the embryonic period. The completion of fetal development results in a newborn who, although still immature in many ways, is capable of survival outside the womb. Sexual Differentiation Sexual differentiation does not begin until the fetal period, during weeks 9–12. Embryonic males and females, though genetically distinguishable, are morphologically identical ( Figure 28.16 ). Bipotential gonads, or gonads that can develop into male or female sexual organs, are connected to a central cavity called the cloaca via Müllerian ducts and Wolffian ducts. (The cloaca is an extension of the primitive gut.) Several events lead to sexual differentiation during this period. During male fetal development, the bipotential gonads become the testes and associated epididymis. The Müllerian ducts degenerate. The Wolffian ducts become the vas deferens, and the cloaca becomes the urethra and rectum. During female fetal development, the bipotential gonads develop into ovaries. The Wolffian ducts degenerate. The Müllerian ducts become the uterine tubes and uterus, and the cloaca divides and develops into a vagina, a urethra, and a rectum. The Fetal Circulatory System During prenatal development, the fetal circulatory system is integrated with the placenta via the umbilical cord so that the fetus receives both oxygen and nutrients from the placenta. However, after childbirth, the umbilical cord is severed, and the newborn’s circulatory system must be reconfigured. When the heart first forms in the embryo, it exists as two parallel tubes derived from mesoderm and lined with endothelium, which then fuse together. As the embryo develops into a fetus, the tube-shaped heart folds and further differentiates into the four chambers present in a mature heart. Unlike a mature cardiovascular system, however, the fetal cardiovascular system also includes circulatory shortcuts, or shunts. A shunt is an anatomical (or sometimes surgical) diversion that allows blood flow to bypass immature organs such as the lungs and liver until childbirth. The placenta provides the fetus with necessary oxygen and nutrients via the umbilical vein. (Remember that veins carry blood toward the heart. In this case, the blood flowing to the fetal heart is oxygenated because it comes from the placenta. The respiratory system is immature and cannot yet oxygenate blood on its own.) From the umbilical vein, the oxygenated blood flows toward the inferior vena cava, all but bypassing the immature liver, via the ductus venosus shunt ( Figure 28.17 ). The liver receives just a trickle of blood, which is all that it needs in its immature, semifunctional state. Blood flows from the inferior vena cava to the right atrium, mixing with fetal venous blood along the way. Although the fetal liver is semifunctional, the fetal lungs are nonfunctional. The fetal circulation therefore bypasses the lungs by shifting some of the blood through the foramen ovale , a shunt that directly connects the right and left atria and avoids the pulmonary trunk altogether. Most of the rest of the blood is pumped to the right ventricle, and from there, into the pulmonary trunk, which splits into pulmonary arteries. However, a shunt within the pulmonary artery, the ductus arteriosus , diverts a portion of this blood into the aorta. This ensures that only a small volume of oxygenated blood passes through the immature pulmonary circuit, which has only minor metabolic requirements. Blood vessels of uninflated lungs have high resistance to flow, a condition that encourages blood to flow to the aorta, which presents much lower resistance. The oxygenated blood moves through the foramen ovale into the left atrium, where it mixes with the now deoxygenated blood returning from the pulmonary circuit. This blood then moves into the left ventricle, where it is pumped into the aorta. Some of this blood moves through the coronary arteries into the myocardium, and some moves through the carotid arteries to the brain. The descending aorta carries partially oxygenated and partially deoxygenated blood into the lower regions of the body. It eventually passes into the umbilical arteries through branches of the internal iliac arteries. The deoxygenated blood collects waste as it circulates through the fetal body and returns to the umbilical cord. Thus, the two umbilical arteries carry blood low in oxygen and high in carbon dioxide and fetal wastes. This blood is filtered through the placenta, where wastes diffuse into the maternal circulation. Oxygen and nutrients from the mother diffuse into the placenta and from there into the fetal blood, and the process repeats. Other Organ Systems During weeks 9–12 of fetal development, the brain continues to expand, the body elongates, and ossification continues. Fetal movements are frequent during this period, but are jerky and not well-controlled. The bone marrow begins to take over the process of erythrocyte production—a task that the liver performed during the embryonic period. The liver now secretes bile. The fetus circulates amniotic fluid by swallowing it and producing urine. The eyes are well-developed by this stage, but the eyelids are fused shut. The fingers and toes begin to develop nails. By the end of week 12, the fetus measures approximately 9 cm (3.5 in) from crown to rump. Weeks 13–16 are marked by sensory organ development. The eyes move closer together; blinking motions begin, although the eyes remain sealed shut. The lips exhibit sucking motions. The ears move upward and lie flatter against the head. The scalp begins to grow hair. The excretory system is also developing: the kidneys are well-formed, and meconium , or fetal feces, begins to accumulate in the intestines. Meconium consists of ingested amniotic fluid, cellular debris, mucus, and bile. During approximately weeks 16–20, as the fetus grows and limb movements become more powerful, the mother may begin to feel quickening , or fetal movements. However, space restrictions limit these movements and typically force the growing fetus into the “fetal position,” with the arms crossed and the legs bent at the knees. Sebaceous glands coat the skin with a waxy, protective substance called vernix caseosa that protects and moisturizes the skin and may provide lubrication during childbirth. A silky hair called lanugo also covers the skin during weeks 17–20, but it is shed as the fetus continues to grow. Extremely premature infants sometimes exhibit residual lanugo. Developmental weeks 21–30 are characterized by rapid weight gain, which is important for maintaining a stable body temperature after birth. The bone marrow completely takes over erythrocyte synthesis, and the axons of the spinal cord begin to be myelinated, or coated in the electrically insulating glial cell sheaths that are necessary for efficient nervous system functioning. (The process of myelination is not completed until adolescence.) During this period, the fetus grows eyelashes. The eyelids are no longer fused and can be opened and closed. The lungs begin producing surfactant, a substance that reduces surface tension in the lungs and assists proper lung expansion after birth. Inadequate surfactant production in premature newborns may result in respiratory distress syndrome, and as a result, the newborn may require surfactant replacement therapy, supplemental oxygen, or maintenance in a continuous positive airway pressure (CPAP) chamber during their first days or weeks of life. In male fetuses, the testes descend into the scrotum near the end of this period. The fetus at 30 weeks measures 28 cm (11 in) from crown to rump and exhibits the approximate body proportions of a full-term newborn, but still is much leaner. Interactive Link Visit this site for a summary of the stages of pregnancy, as experienced by the mother, and view the stages of development of the fetus throughout gestation. At what point in fetal development can a regular heartbeat be detected? The fetus continues to lay down subcutaneous fat from week 31 until birth. The added fat fills out the hypodermis, and the skin transitions from red and wrinkled to soft and pink. Lanugo is shed, and the nails grow to the tips of the fingers and toes. Immediately before birth, the average crown-to-rump length is 35.5–40.5 cm (14–16 in), and the fetus weighs approximately 2.5–4 kg (5.5–8.8 lbs). Once born, the newborn is no longer confined to the fetal position, so subsequent measurements are made from head-to-toe instead of from crown-to-rump. At birth, the average length is approximately 51 cm (20 in). Disorders of the... Developing Fetus Throughout the second half of gestation, the fetal intestines accumulate a tarry, greenish black meconium. The newborn’s first stools consist almost entirely of meconium; they later transition to seedy yellow stools or slightly formed tan stools as meconium is cleared and replaced with digested breast milk or formula, respectively. Unlike these later stools, meconium is sterile; it is devoid of bacteria because the fetus is in a sterile environment and has not consumed any breast milk or formula. Typically, an infant does not pass meconium until after birth. However, in 5–20 percent of births, the fetus has a bowel movement in utero, which can cause major complications in the newborn. The passage of meconium in the uterus signals fetal distress, particularly fetal hypoxia (i.e., oxygen deprivation). This may be caused by maternal drug abuse (especially tobacco or cocaine), maternal hypertension, depletion of amniotic fluid, long labor or difficult birth, or a defect in the placenta that prevents it from delivering adequate oxygen to the fetus. Meconium passage is typically a complication of full-term or post-term newborns because it is rarely passed before 34 weeks of gestation, when the gastrointestinal system has matured and is appropriately controlled by nervous system stimuli. Fetal distress can stimulate the vagus nerve to trigger gastrointestinal peristalsis and relaxation of the anal sphincter. Notably, fetal hypoxic stress also induces a gasping reflex, increasing the likelihood that meconium will be inhaled into the fetal lungs. Although meconium is a sterile substance, it interferes with the antibiotic properties of the amniotic fluid and makes the newborn and mother more vulnerable to bacterial infections at birth and during the perinatal period. Specifically, inflammation of the fetal membranes, inflammation of the uterine lining, or neonatal sepsis (infection in the newborn) may occur. Meconium also irritates delicate fetal skin and can cause a rash. The first sign that a fetus has passed meconium usually does not come until childbirth, when the amniotic sac ruptures. Normal amniotic fluid is clear and watery, but amniotic fluid in which meconium has been passed is stained greenish or yellowish. Antibiotics given to the mother may reduce the incidence of maternal bacterial infections, but it is critical that meconium is aspirated from the newborn before the first breath. Under these conditions, an obstetrician will extensively aspirate the infant’s airways as soon as the head is delivered, while the rest of the infant’s body is still inside the birth canal. Aspiration of meconium with the first breath can result in labored breathing, a barrel-shaped chest, or a low Apgar score. An obstetrician can identify meconium aspiration by listening to the lungs with a stethoscope for a coarse rattling sound. Blood gas tests and chest X-rays of the infant can confirm meconium aspiration. Inhaled meconium after birth could obstruct a newborn’s airways leading to alveolar collapse, interfere with surfactant function by stripping it from the lungs, or cause pulmonary inflammation or hypertension. Any of these complications will make the newborn much more vulnerable to pulmonary infection, including pneumonia. 28.4 Maternal Changes During Pregnancy, Labor, and Birth Learning Objectives By the end of this section, you will be able to: Explain how estrogen, progesterone, and hCG are involved in maintaining pregnancy List the contributors to weight gain during pregnancy Describe the major changes to the maternal digestive, circulatory, and integumentary systems during pregnancy Summarize the events leading to labor Identify and describe each of the three stages of childbirth A full-term pregnancy lasts approximately 270 days (approximately 38.5 weeks) from conception to birth. Because it is easier to remember the first day of the last menstrual period (LMP) than to estimate the date of conception, obstetricians set the due date as 284 days (approximately 40.5 weeks) from the LMP. This assumes that conception occurred on day 14 of the woman’s cycle, which is usually a good approximation. The 40 weeks of an average pregnancy are usually discussed in terms of three trimesters , each approximately 13 weeks. During the second and third trimesters, the pre-pregnancy uterus—about the size of a fist—grows dramatically to contain the fetus, causing a number of anatomical changes in the mother ( Figure 28.18 ). Effects of Hormones Virtually all of the effects of pregnancy can be attributed in some way to the influence of hormones—particularly estrogens, progesterone, and hCG. During weeks 7–12 from the LMP, the pregnancy hormones are primarily generated by the corpus luteum. Progesterone secreted by the corpus luteum stimulates the production of decidual cells of the endometrium that nourish the blastocyst before placentation. As the placenta develops and the corpus luteum degenerates during weeks 12–17, the placenta gradually takes over as the endocrine organ of pregnancy. The placenta converts weak androgens secreted by the maternal and fetal adrenal glands to estrogens, which are necessary for pregnancy to progress. Estrogen levels climb throughout the pregnancy, increasing 30-fold by childbirth. Estrogens have the following actions: They suppress FSH and LH production, effectively preventing ovulation. (This function is the biological basis of hormonal birth control pills.) They induce the growth of fetal tissues and are necessary for the maturation of the fetal lungs and liver. They promote fetal viability by regulating progesterone production and triggering fetal synthesis of cortisol, which helps with the maturation of the lungs, liver, and endocrine organs such as the thyroid gland and adrenal gland. They stimulate maternal tissue growth, leading to uterine enlargement and mammary duct expansion and branching. Relaxin, another hormone secreted by the corpus luteum and then by the placenta, helps prepare the mother’s body for childbirth. It increases the elasticity of the symphysis pubis joint and pelvic ligaments, making room for the growing fetus and allowing expansion of the pelvic outlet for childbirth. Relaxin also helps dilate the cervix during labor. The placenta takes over the synthesis and secretion of progesterone throughout pregnancy as the corpus luteum degenerates. Like estrogen, progesterone suppresses FSH and LH. It also inhibits uterine contractions, protecting the fetus from preterm birth. This hormone decreases in late gestation, allowing uterine contractions to intensify and eventually progress to true labor. The placenta also produces hCG. In addition to promoting survival of the corpus luteum, hCG stimulates the male fetal gonads to secrete testosterone, which is essential for the development of the male reproductive system. The anterior pituitary enlarges and ramps up its hormone production during pregnancy, raising the levels of thyrotropin, prolactin, and adrenocorticotropic hormone (ACTH). Thyrotropin, in conjunction with placental hormones, increases the production of thyroid hormone, which raises the maternal metabolic rate. This can markedly augment a pregnant woman’s appetite and cause hot flashes. Prolactin stimulates enlargement of the mammary glands in preparation for milk production. ACTH stimulates maternal cortisol secretion, which contributes to fetal protein synthesis. In addition to the pituitary hormones, increased parathyroid levels mobilize calcium from maternal bones for fetal use. Weight Gain The second and third trimesters of pregnancy are associated with dramatic changes in maternal anatomy and physiology. The most obvious anatomical sign of pregnancy is the dramatic enlargement of the abdominal region, coupled with maternal weight gain. This weight results from the growing fetus as well as the enlarged uterus, amniotic fluid, and placenta. Additional breast tissue and dramatically increased blood volume also contribute to weight gain ( Table 28.2 ). Surprisingly, fat storage accounts for only approximately 2.3 kg (5 lbs) in a normal pregnancy and serves as a reserve for the increased metabolic demand of breastfeeding. During the first trimester, the mother does not need to consume additional calories to maintain a healthy pregnancy. However, a weight gain of approximately 0.45 kg (1 lb) per month is common. During the second and third trimesters, the mother’s appetite increases, but it is only necessary for her to consume an additional 300 calories per day to support the growing fetus. Most women gain approximately 0.45 kg (1 lb) per week. Contributors to Weight Gain During Pregnancy Component Weight (kg) Weight (lb) Fetus 3.2–3.6 7–8 Placenta and fetal membranes 0.9–1.8 2–4 Amniotic fluid 0.9–1.4 2–3 Breast tissue 0.9–1.4 2–3 Blood 1.4 4 Fat 0.9–4.1 3–9 Uterus 0.9–2.3 2–5 Total 10–16.3 22–36 Table 28.2 Changes in Organ Systems During Pregnancy As the woman’s body adapts to pregnancy, characteristic physiologic changes occur. These changes can sometimes prompt symptoms often referred to collectively as the common discomforts of pregnancy. Digestive and Urinary System Changes Nausea and vomiting, sometimes triggered by an increased sensitivity to odors, are common during the first few weeks to months of pregnancy. This phenomenon is often referred to as “morning sickness,” although the nausea may persist all day. The source of pregnancy nausea is thought to be the increased circulation of pregnancy-related hormones, specifically circulating estrogen, progesterone, and hCG. Decreased intestinal peristalsis may also contribute to nausea. By about week 12 of pregnancy, nausea typically subsides. A common gastrointestinal complaint during the later stages of pregnancy is gastric reflux, or heartburn, which results from the upward, constrictive pressure of the growing uterus on the stomach. The same decreased peristalsis that may contribute to nausea in early pregnancy is also thought to be responsible for pregnancy-related constipation as pregnancy progresses. The downward pressure of the uterus also compresses the urinary bladder, leading to frequent urination. The problem is exacerbated by increased urine production. In addition, the maternal urinary system processes both maternal and fetal wastes, further increasing the total volume of urine. Circulatory System Changes Blood volume increases substantially during pregnancy, so that by childbirth, it exceeds its preconception volume by 30 percent, or approximately 1–2 liters. The greater blood volume helps to manage the demands of fetal nourishment and fetal waste removal. In conjunction with increased blood volume, the pulse and blood pressure also rise moderately during pregnancy. As the fetus grows, the uterus compresses underlying pelvic blood vessels, hampering venous return from the legs and pelvic region. As a result, many pregnant women develop varicose veins or hemorrhoids. Respiratory System Changes During the second half of pregnancy, the respiratory minute volume (volume of gas inhaled or exhaled by the lungs per minute) increases by 50 percent to compensate for the oxygen demands of the fetus and the increased maternal metabolic rate. The growing uterus exerts upward pressure on the diaphragm, decreasing the volume of each inspiration and potentially causing shortness of breath, or dyspnea. During the last several weeks of pregnancy, the pelvis becomes more elastic, and the fetus descends lower in a process called lightening . This typically ameliorates dyspnea. The respiratory mucosa swell in response to increased blood flow during pregnancy, leading to nasal congestion and nose bleeds, particularly when the weather is cold and dry. Humidifier use and increased fluid intake are often recommended to counteract congestion. Integumentary System Changes The dermis stretches extensively to accommodate the growing uterus, breast tissue, and fat deposits on the thighs and hips. Torn connective tissue beneath the dermis can cause striae (stretch marks) on the abdomen, which appear as red or purple marks during pregnancy that fade to a silvery white color in the months after childbirth. An increase in melanocyte-stimulating hormone, in conjunction with estrogens, darkens the areolae and creates a line of pigment from the umbilicus to the pubis called the linea nigra ( Figure 28.19 ). Melanin production during pregnancy may also darken or discolor skin on the face to create a chloasma, or “mask of pregnancy.” Physiology of Labor Childbirth, or parturition , typically occurs within a week of a woman’s due date, unless the woman is pregnant with more than one fetus, which usually causes her to go into labor early. As a pregnancy progresses into its final weeks, several physiological changes occur in response to hormones that trigger labor. First, recall that progesterone inhibits uterine contractions throughout the first several months of pregnancy. As the pregnancy enters its seventh month, progesterone levels plateau and then drop. Estrogen levels, however, continue to rise in the maternal circulation ( Figure 28.20 ). The increasing ratio of estrogen to progesterone makes the myometrium (the uterine smooth muscle) more sensitive to stimuli that promote contractions (because progesterone no longer inhibits them). Moreover, in the eighth month of pregnancy, fetal cortisol rises, which boosts estrogen secretion by the placenta and further overpowers the uterine-calming effects of progesterone. Some women may feel the result of the decreasing levels of progesterone in late pregnancy as weak and irregular peristaltic Braxton Hicks contractions , also called false labor. These contractions can often be relieved with rest or hydration. A common sign that labor will be short is the so-called “bloody show.” During pregnancy, a plug of mucus accumulates in the cervical canal, blocking the entrance to the uterus. Approximately 1–2 days prior to the onset of true labor, this plug loosens and is expelled, along with a small amount of blood. Meanwhile, the posterior pituitary has been boosting its secretion of oxytocin, a hormone that stimulates the contractions of labor. At the same time, the myometrium increases its sensitivity to oxytocin by expressing more receptors for this hormone. As labor nears, oxytocin begins to stimulate stronger, more painful uterine contractions, which—in a positive feedback loop—stimulate the secretion of prostaglandins from fetal membranes. Like oxytocin, prostaglandins also enhance uterine contractile strength. The fetal pituitary also secretes oxytocin, which increases prostaglandins even further. Given the importance of oxytocin and prostaglandins to the initiation and maintenance of labor, it is not surprising that, when a pregnancy is not progressing to labor and needs to be induced, a pharmaceutical version of these compounds (called pitocin) is administered by intravenous drip. Finally, stretching of the myometrium and cervix by a full-term fetus in the vertex (head-down) position is regarded as a stimulant to uterine contractions. The sum of these changes initiates the regular contractions known as true labor , which become more powerful and more frequent with time. The pain of labor is attributed to myometrial hypoxia during uterine contractions. Stages of Childbirth The process of childbirth can be divided into three stages: cervical dilation, expulsion of the newborn, and afterbirth ( Figure 28.21 ). Cervical Dilation For vaginal birth to occur, the cervix must dilate fully to 10 cm in diameter—wide enough to deliver the newborn’s head. The dilation stage is the longest stage of labor and typically takes 6–12 hours. However, it varies widely and may take minutes, hours, or days, depending in part on whether the mother has given birth before; in each subsequent labor, this stage tends to be shorter. True labor progresses in a positive feedback loop in which uterine contractions stretch the cervix, causing it to dilate and efface, or become thinner. Cervical stretching induces reflexive uterine contractions that dilate and efface the cervix further. In addition, cervical dilation boosts oxytocin secretion from the pituitary, which in turn triggers more powerful uterine contractions. When labor begins, uterine contractions may occur only every 3–30 minutes and last only 20–40 seconds; however, by the end of this stage, contractions may occur as frequently as every 1.5–2 minutes and last for a full minute. Each contraction sharply reduces oxygenated blood flow to the fetus. For this reason, it is critical that a period of relaxation occur after each contraction. Fetal distress, measured as a sustained decrease or increase in the fetal heart rate, can result from severe contractions that are too powerful or lengthy for oxygenated blood to be restored to the fetus. Such a situation can be cause for an emergency birth with vacuum, forceps, or surgically by Caesarian section. The amniotic membranes rupture before the onset of labor in about 12 percent of women; they typically rupture at the end of the dilation stage in response to excessive pressure from the fetal head entering the birth canal. Expulsion Stage The expulsion stage begins when the fetal head enters the birth canal and ends with birth of the newborn. It typically takes up to 2 hours, but it can last longer or be completed in minutes, depending in part on the orientation of the fetus. The vertex presentation known as the occiput anterior vertex is the most common presentation and is associated with the greatest ease of vaginal birth. The fetus faces the maternal spinal cord and the smallest part of the head (the posterior aspect called the occiput) exits the birth canal first. In fewer than 5 percent of births, the infant is oriented in the breech presentation, or buttocks down. In a complete breech, both legs are crossed and oriented downward. In a frank breech presentation, the legs are oriented upward. Before the 1960s, it was common for breech presentations to be delivered vaginally. Today, most breech births are accomplished by Caesarian section. Vaginal birth is associated with significant stretching of the vaginal canal, the cervix, and the perineum. Until recent decades, it was routine procedure for an obstetrician to numb the perineum and perform an episiotomy , an incision in the posterior vaginal wall and perineum. The perineum is now more commonly allowed to tear on its own during birth. Both an episiotomy and a perineal tear need to be sutured shortly after birth to ensure optimal healing. Although suturing the jagged edges of a perineal tear may be more difficult than suturing an episiotomy, tears heal more quickly, are less painful, and are associated with less damage to the muscles around the vagina and rectum. Upon birth of the newborn’s head, an obstetrician will aspirate mucus from the mouth and nose before the newborn’s first breath. Once the head is birthed, the rest of the body usually follows quickly. The umbilical cord is then double-clamped, and a cut is made between the clamps. This completes the second stage of childbirth. Afterbirth The delivery of the placenta and associated membranes, commonly referred to as the afterbirth , marks the final stage of childbirth. After expulsion of the newborn, the myometrium continues to contract. This movement shears the placenta from the back of the uterine wall. It is then easily delivered through the vagina. Continued uterine contractions then reduce blood loss from the site of the placenta. Delivery of the placenta marks the beginning of the postpartum period—the period of approximately 6 weeks immediately following childbirth during which the mother’s body gradually returns to a non-pregnant state. If the placenta does not birth spontaneously within approximately 30 minutes, it is considered retained, and the obstetrician may attempt manual removal. If this is not successful, surgery may be required. It is important that the obstetrician examines the expelled placenta and fetal membranes to ensure that they are intact. If fragments of the placenta remain in the uterus, they can cause postpartum hemorrhage. Uterine contractions continue for several hours after birth to return the uterus to its pre-pregnancy size in a process called involution , which also allows the mother’s abdominal organs to return to their pre-pregnancy locations. Breastfeeding facilitates this process. Although postpartum uterine contractions limit blood loss from the detachment of the placenta, the mother does experience a postpartum vaginal discharge called lochia . This is made up of uterine lining cells, erythrocytes, leukocytes, and other debris. Thick, dark, lochia rubra (red lochia) typically continues for 2–3 days, and is replaced by lochia serosa, a thinner, pinkish form that continues until about the tenth postpartum day. After this period, a scant, creamy, or watery discharge called lochia alba (white lochia) may continue for another 1–2 weeks. 28.5 Adjustments of the Infant at Birth and Postnatal Stages Learning Objectives By the end of this section, you will be able to: Discuss the importance of an infant’s first breath Explain the closing of the cardiac shunts Describe thermoregulation in the newborn Summarize the importance of intestinal flora in the newborn From a fetal perspective, the process of birth is a crisis. In the womb, the fetus was snuggled in a soft, warm, dark, and quiet world. The placenta provided nutrition and oxygen continuously. Suddenly, the contractions of labor and vaginal childbirth forcibly squeeze the fetus through the birth canal, limiting oxygenated blood flow during contractions and shifting the skull bones to accommodate the small space. After birth, the newborn’s system must make drastic adjustments to a world that is colder, brighter, and louder, and where he or she will experience hunger and thirst. The neonatal period (neo- = “new”; -natal = “birth”) spans the first to the thirtieth day of life outside of the uterus. Respiratory Adjustments Although the fetus “practices” breathing by inhaling amniotic fluid in utero, there is no air in the uterus and thus no true opportunity to breathe. (There is also no need to breathe because the placenta supplies the fetus with all the oxygenated blood it needs.) During gestation, the partially collapsed lungs are filled with amniotic fluid and exhibit very little metabolic activity. Several factors stimulate newborns to take their first breath at birth. First, labor contractions temporarily constrict umbilical blood vessels, reducing oxygenated blood flow to the fetus and elevating carbon dioxide levels in the blood. High carbon dioxide levels cause acidosis and stimulate the respiratory center in the brain, triggering the newborn to take a breath. The first breath typically is taken within 10 seconds of birth, after mucus is aspirated from the infant’s mouth and nose. The first breaths inflate the lungs to nearly full capacity and dramatically decrease lung pressure and resistance to blood flow, causing a major circulatory reconfiguration. Pulmonary alveoli open, and alveolar capillaries fill with blood. Amniotic fluid in the lungs drains or is absorbed, and the lungs immediately take over the task of the placenta, exchanging carbon dioxide for oxygen by the process of respiration. Circulatory Adjustments The process of clamping and cutting the umbilical cord collapses the umbilical blood vessels. In the absence of medical assistance, this occlusion would occur naturally within 20 minutes of birth because the Wharton’s jelly within the umbilical cord would swell in response to the lower temperature outside of the mother’s body, and the blood vessels would constrict. Natural occlusion has occurred when the umbilical cord is no longer pulsating. For the most part, the collapsed vessels atrophy and become fibrotic remnants, existing in the mature circulatory system as ligaments of the abdominal wall and liver. The ductus venosus degenerates to become the ligamentum venosum beneath the liver. Only the proximal sections of the two umbilical arteries remain functional, taking on the role of supplying blood to the upper part of the bladder ( Figure 28.22 ). The newborn’s first breath is vital to initiate the transition from the fetal to the neonatal circulatory pattern. Inflation of the lungs decreases blood pressure throughout the pulmonary system, as well as in the right atrium and ventricle. In response to this pressure change, the flow of blood temporarily reverses direction through the foramen ovale, moving from the left to the right atrium, and blocking the shunt with two flaps of tissue. Within 1 year, the tissue flaps usually fuse over the shunt, turning the foramen ovale into the fossa ovalis. The ductus arteriosus constricts as a result of increased oxygen concentration, and becomes the ligamentum arteriosum. Closing of the ductus arteriosus ensures that all blood pumped to the pulmonary circuit will be oxygenated by the newly functional neonatal lungs. Thermoregulatory Adjustments The fetus floats in warm amniotic fluid that is maintained at a temperature of approximately 98.6°F with very little fluctuation. Birth exposes newborns to a cooler environment in which they have to regulate their own body temperature. Newborns have a higher ratio of surface area to volume than adults. This means that their body has less volume throughout which to produce heat, and more surface area from which to lose heat. As a result, newborns produce heat more slowly and lose it more quickly. Newborns also have immature musculature that limits their ability to generate heat by shivering. Moreover, their nervous systems are underdeveloped, so they cannot quickly constrict superficial blood vessels in response to cold. They also have little subcutaneous fat for insulation. All these factors make it harder for newborns to maintain their body temperature. Newborns, however, do have a special method for generating heat: nonshivering thermogenesis , which involves the breakdown of brown adipose tissue , or brown fat, which is distributed over the back, chest, and shoulders. Brown fat differs from the more familiar white fat in two ways: It is highly vascularized. This allows for faster delivery of oxygen, which leads to faster cellular respiration. It is packed with a special type of mitochondria that are able to engage in cellular respiration reactions that produce less ATP and more heat than standard cellular respiration reactions. The breakdown of brown fat occurs automatically upon exposure to cold, so it is an important heat regulator in newborns. During fetal development, the placenta secretes inhibitors that prevent metabolism of brown adipose fat and promote its accumulation in preparation for birth. Gastrointestinal and Urinary Adjustments In adults, the gastrointestinal tract harbors bacterial flora—trillions of bacteria that aid in digestion, produce vitamins, and protect from the invasion or replication of pathogens. In stark contrast, the fetal intestine is sterile. The first consumption of breast milk or formula floods the neonatal gastrointestinal tract with beneficial bacteria that begin to establish the bacterial flora. The fetal kidneys filter blood and produce urine, but the neonatal kidneys are still immature and inefficient at concentrating urine. Therefore, newborns produce very dilute urine, making it particularly important for infants to obtain sufficient fluids from breast milk or formula. Homeostatic Imbalances Homeostasis in the Newborn: Apgar Score In the minutes following birth, a newborn must undergo dramatic systemic changes to be able to survive outside the womb. An obstetrician, midwife, or nurse can estimate how well a newborn is doing by obtaining an Apgar score. The Apgar score was introduced in 1952 by the anesthesiologist Dr. Virginia Apgar as a method to assess the effects on the newborn of anesthesia given to the laboring mother. Healthcare providers now use it to assess the general wellbeing of the newborn, whether or not analgesics or anesthetics were used. Five criteria—skin color, heart rate, reflex, muscle tone, and respiration—are assessed, and each criterion is assigned a score of 0, 1, or 2. Scores are taken at 1 minute after birth and again at 5 minutes after birth. Each time that scores are taken, the five scores are added together. High scores (out of a possible 10) indicate the baby has made the transition from the womb well, whereas lower scores indicate that the baby may be in distress. The technique for determining an Apgar score is quick and easy, painless for the newborn, and does not require any instruments except for a stethoscope. A convenient way to remember the five scoring criteria is to apply the mnemonic APGAR, for “appearance” (skin color), “pulse” (heart rate), “grimace” (reflex), “activity” (muscle tone), and “respiration.” Of the five Apgar criteria, heart rate and respiration are the most critical. Poor scores for either of these measurements may indicate the need for immediate medical attention to resuscitate or stabilize the newborn. In general, any score lower than 7 at the 5-minute mark indicates that medical assistance may be needed. A total score below 5 indicates an emergency situation. Normally, a newborn will get an intermediate score of 1 for some of the Apgar criteria and will progress to a 2 by the 5-minute assessment. Scores of 8 or above are normal. 28.6 Lactation Learning Objectives By the end of this section, you will be able to: Describe the structure of the lactating breast Summarize the process of lactation Explain how the composition of breast milk changes during the first days of lactation and in the course of a single feeding Lactation is the process by which milk is synthesized and secreted from the mammary glands of the postpartum female breast in response to an infant sucking at the nipple. Breast milk provides ideal nutrition and passive immunity for the infant, encourages mild uterine contractions to return the uterus to its pre-pregnancy size (i.e., involution), and induces a substantial metabolic increase in the mother, consuming the fat reserves stored during pregnancy. Structure of the Lactating Breast Mammary glands are modified sweat glands. The non-pregnant and non-lactating female breast is composed primarily of adipose and collagenous tissue, with mammary glands making up a very minor proportion of breast volume. The mammary gland is composed of milk-transporting lactiferous ducts, which expand and branch extensively during pregnancy in response to estrogen, growth hormone, cortisol, and prolactin. Moreover, in response to progesterone, clusters of breast alveoli bud from the ducts and expand outward toward the chest wall. Breast alveoli are balloon-like structures lined with milk-secreting cuboidal cells, or lactocytes, that are surrounded by a net of contractile myoepithelial cells. Milk is secreted from the lactocytes, fills the alveoli, and is squeezed into the ducts. Clusters of alveoli that drain to a common duct are called lobules; the lactating female has 12–20 lobules organized radially around the nipple. Milk drains from lactiferous ducts into lactiferous sinuses that meet at 4 to 18 perforations in the nipple, called nipple pores. The small bumps of the areola (the darkened skin around the nipple) are called Montgomery glands. They secrete oil to cleanse the nipple opening and prevent chapping and cracking of the nipple during breastfeeding. The Process of Lactation The pituitary hormone prolactin is instrumental in the establishment and maintenance of breast milk supply. It also is important for the mobilization of maternal micronutrients for breast milk. Near the fifth week of pregnancy, the level of circulating prolactin begins to increase, eventually rising to approximately 10–20 times the pre-pregnancy concentration. We noted earlier that, during pregnancy, prolactin and other hormones prepare the breasts anatomically for the secretion of milk. The level of prolactin plateaus in late pregnancy, at a level high enough to initiate milk production. However, estrogen, progesterone, and other placental hormones inhibit prolactin-mediated milk synthesis during pregnancy. It is not until the placenta is expelled that this inhibition is lifted and milk production commences. After childbirth, the baseline prolactin level drops sharply, but it is restored for a 1-hour spike during each feeding to stimulate the production of milk for the next feeding. With each prolactin spike, estrogen and progesterone also increase slightly. When the infant suckles, sensory nerve fibers in the areola trigger a neuroendocrine reflex that results in milk secretion from lactocytes into the alveoli. The posterior pituitary releases oxytocin, which stimulates myoepithelial cells to squeeze milk from the alveoli so it can drain into the lactiferous ducts, collect in the lactiferous sinuses, and discharge through the nipple pores. It takes less than 1 minute from the time when an infant begins suckling (the latent period) until milk is secreted (the let-down). Figure 28.23 summarizes the positive feedback loop of the let-down reflex . The prolactin-mediated synthesis of milk changes with time. Frequent milk removal by breastfeeding (or pumping) will maintain high circulating prolactin levels for several months. However, even with continued breastfeeding, baseline prolactin will decrease over time to its pre-pregnancy level. In addition to prolactin and oxytocin, growth hormone, cortisol, parathyroid hormone, and insulin contribute to lactation, in part by facilitating the transport of maternal amino acids, fatty acids, glucose, and calcium to breast milk. Changes in the Composition of Breast Milk In the final weeks of pregnancy, the alveoli swell with colostrum , a thick, yellowish substance that is high in protein but contains less fat and glucose than mature breast milk ( Table 28.3 ). Before childbirth, some women experience leakage of colostrum from the nipples. In contrast, mature breast milk does not leak during pregnancy and is not secreted until several days after childbirth. Compositions of Human Colostrum, Mature Breast Milk, and Cow’s Milk (g/L) Human colostrum Human breast milk Cow’s milk* Total protein 23 11 31 Immunoglobulins 19 0.1 1 Fat 30 45 38 Lactose 57 71 47 Calcium 0.5 0.3 1.4 Phosphorus 0.16 0.14 0.90 Sodium 0.50 0.15 0.41 Table 28.3 *Cow’s milk should never be given to an infant. Its composition is not suitable and its proteins are difficult for the infant to digest. Colostrum is secreted during the first 48–72 hours postpartum. Only a small volume of colostrum is produced—approximately 3 ounces in a 24-hour period—but it is sufficient for the newborn in the first few days of life. Colostrum is rich with immunoglobulins, which confer gastrointestinal, and also likely systemic, immunity as the newborn adjusts to a nonsterile environment. After about the third postpartum day, the mother secretes transitional milk that represents an intermediate between mature milk and colostrum. This is followed by mature milk from approximately postpartum day 10 (see Table 28.3 ). As you can see in the accompanying table, cow’s milk is not a substitute for breast milk. It contains less lactose, less fat, and more protein and minerals. Moreover, the proteins in cow’s milk are difficult for an infant’s immature digestive system to metabolize and absorb. The first few weeks of breastfeeding may involve leakage, soreness, and periods of milk engorgement as the relationship between milk supply and infant demand becomes established. Once this period is complete, the mother will produce approximately 1.5 liters of milk per day for a single infant, and more if she has twins or triplets. As the infant goes through growth spurts, the milk supply constantly adjusts to accommodate changes in demand. A woman can continue to lactate for years, but once breastfeeding is stopped for approximately 1 week, any remaining milk will be reabsorbed; in most cases, no more will be produced, even if suckling or pumping is resumed. Mature milk changes from the beginning to the end of a feeding. The early milk, called foremilk , is watery, translucent, and rich in lactose and protein. Its purpose is to quench the infant’s thirst. Hindmilk is delivered toward the end of a feeding. It is opaque, creamy, and rich in fat, and serves to satisfy the infant’s appetite. During the first days of a newborn’s life, it is important for meconium to be cleared from the intestines and for bilirubin to be kept low in the circulation. Recall that bilirubin, a product of erythrocyte breakdown, is processed by the liver and secreted in bile. It enters the gastrointestinal tract and exits the body in the stool. Breast milk has laxative properties that help expel meconium from the intestines and clear bilirubin through the excretion of bile. A high concentration of bilirubin in the blood causes jaundice. Some degree of jaundice is normal in newborns, but a high level of bilirubin—which is neurotoxic—can cause brain damage. Newborns, who do not yet have a fully functional blood–brain barrier, are highly vulnerable to the bilirubin circulating in the blood. Indeed, hyperbilirubinemia, a high level of circulating bilirubin, is the most common condition requiring medical attention in newborns. Newborns with hyperbilirubinemia are treated with phototherapy because UV light helps to break down the bilirubin quickly. 28.7 Patterns of Inheritance Learning Objectives By the end of this section, you will be able to: Differentiate between genotype and phenotype Describe how alleles determine a person’s traits Summarize Mendel’s experiments and relate them to human genetics Explain the inheritance of autosomal dominant and recessive and sex-linked genetic disorders We have discussed the events that lead to the development of a newborn. But what makes each newborn unique? The answer lies, of course, in the DNA in the sperm and oocyte that combined to produce that first diploid cell, the human zygote. From Genotype to Phenotype Each human body cell has a full complement of DNA stored in 23 pairs of chromosomes. Figure 28.24 shows the pairs in a systematic arrangement called a karyotype . Among these is one pair of chromosomes, called the sex chromosomes , that determines the sex of the individual (XX in females, XY in males). The remaining 22 chromosome pairs are called autosomal chromosomes . Each of these chromosomes carries hundreds or even thousands of genes, each of which codes for the assembly of a particular protein—that is, genes are “expressed” as proteins. An individual’s complete genetic makeup is referred to as his or her genotype . The characteristics that the genes express, whether they are physical, behavioral, or biochemical, are a person’s phenotype . You inherit one chromosome in each pair—a full complement of 23—from each parent. This occurs when the sperm and oocyte combine at the moment of your conception. Homologous chromosomes—those that make up a complementary pair—have genes for the same characteristics in the same location on the chromosome. Because one copy of a gene, an allele , is inherited from each parent, the alleles in these complementary pairs may vary. Take for example an allele that encodes for dimples. A child may inherit the allele encoding for dimples on the chromosome from the father and the allele that encodes for smooth skin (no dimples) on the chromosome from the mother. Although a person can have two identical alleles for a single gene (a homozygous state), it is also possible for a person to have two different alleles (a heterozygous state). The two alleles can interact in several different ways. The expression of an allele can be dominant, for which the activity of this gene will mask the expression of a nondominant, or recessive, allele. Sometimes dominance is complete; at other times, it is incomplete. In some cases, both alleles are expressed at the same time in a form of expression known as codominance. In the simplest scenario, a single pair of genes will determine a single heritable characteristic. However, it is quite common for multiple genes to interact to confer a feature. For instance, eight or more genes—each with their own alleles—determine eye color in humans. Moreover, although any one person can only have two alleles corresponding to a given gene, more than two alleles commonly exist in a population. This phenomenon is called multiple alleles. For example, there are three different alleles that encode ABO blood type; these are designated I A , I B , and i. Over 100 years of theoretical and experimental genetics studies, and the more recent sequencing and annotation of the human genome, have helped scientists to develop a better understanding of how an individual’s genotype is expressed as their phenotype. This body of knowledge can help scientists and medical professionals to predict, or at least estimate, some of the features that an offspring will inherit by examining the genotypes or phenotypes of the parents. One important application of this knowledge is to identify an individual’s risk for certain heritable genetic disorders. However, most diseases have a multigenic pattern of inheritance and can also be affected by the environment, so examining the genotypes or phenotypes of a person’s parents will provide only limited information about the risk of inheriting a disease. Only for a handful of single-gene disorders can genetic testing allow clinicians to calculate the probability with which a child born to the two parents tested may inherit a specific disease. Mendel’s Theory of Inheritance Our contemporary understanding of genetics rests on the work of a nineteenth-century monk. Working in the mid-1800s, long before anyone knew about genes or chromosomes, Gregor Mendel discovered that garden peas transmit their physical characteristics to subsequent generations in a discrete and predictable fashion. When he mated, or crossed, two pure-breeding pea plants that differed by a certain characteristic, the first-generation offspring all looked like one of the parents. For instance, when he crossed tall and dwarf pure-breeding pea plants, all of the offspring were tall. Mendel called tallness dominant because it was expressed in offspring when it was present in a purebred parent. He called dwarfism recessive because it was masked in the offspring if one of the purebred parents possessed the dominant characteristic. Note that tallness and dwarfism are variations on the characteristic of height. Mendel called such a variation a trait . We now know that these traits are the expression of different alleles of the gene encoding height. Mendel performed thousands of crosses in pea plants with differing traits for a variety of characteristics. And he repeatedly came up with the same results—among the traits he studied, one was always dominant, and the other was always recessive. (Remember, however, that this dominant–recessive relationship between alleles is not always the case; some alleles are codominant, and sometimes dominance is incomplete.) Using his understanding of dominant and recessive traits, Mendel tested whether a recessive trait could be lost altogether in a pea lineage or whether it would resurface in a later generation. By crossing the second-generation offspring of purebred parents with each other, he showed that the latter was true: recessive traits reappeared in third-generation plants in a ratio of 3:1 (three offspring having the dominant trait and one having the recessive trait). Mendel then proposed that characteristics such as height were determined by heritable “factors” that were transmitted, one from each parent, and inherited in pairs by offspring. In the language of genetics, Mendel’s theory applied to humans says that if an individual receives two dominant alleles, one from each parent, the individual’s phenotype will express the dominant trait. If an individual receives two recessive alleles, then the recessive trait will be expressed in the phenotype. Individuals who have two identical alleles for a given gene, whether dominant or recessive, are said to be homozygous for that gene (homo- = “same”). Conversely, an individual who has one dominant allele and one recessive allele is said to be heterozygous for that gene (hetero- = “different” or “other”). In this case, the dominant trait will be expressed, and the individual will be phenotypically identical to an individual who possesses two dominant alleles for the trait. It is common practice in genetics to use capital and lowercase letters to represent dominant and recessive alleles. Using Mendel’s pea plants as an example, if a tall pea plant is homozygous, it will possess two tall alleles ( TT ). A dwarf pea plant must be homozygous because its dwarfism can only be expressed when two recessive alleles are present ( tt ). A heterozygous pea plant ( Tt ) would be tall and phenotypically indistinguishable from a tall homozygous pea plant because of the dominant tall allele. Mendel deduced that a 3:1 ratio of dominant to recessive would be produced by the random segregation of heritable factors (genes) when crossing two heterozygous pea plants. In other words, for any given gene, parents are equally likely to pass down either one of their alleles to their offspring in a haploid gamete, and the result will be expressed in a dominant–recessive pattern if both parents are heterozygous for the trait. Because of the random segregation of gametes, the laws of chance and probability come into play when predicting the likelihood of a given phenotype. Consider a cross between an individual with two dominant alleles for a trait ( AA ) and an individual with two recessive alleles for the same trait ( aa ). All of the parental gametes from the dominant individual would be A , and all of the parental gametes from the recessive individual would be a ( Figure 28.25 ). All of the offspring of that second generation, inheriting one allele from each parent, would have the genotype Aa , and the probability of expressing the phenotype of the dominant allele would be 4 out of 4, or 100 percent. This seems simple enough, but the inheritance pattern gets interesting when the second-generation Aa individuals are crossed. In this generation, 50 percent of each parent’s gametes are A and the other 50 percent are a . By Mendel’s principle of random segregation, the possible combinations of gametes that the offspring can receive are AA , Aa , aA (which is the same as Aa ), and aa . Because segregation and fertilization are random, each offspring has a 25 percent chance of receiving any of these combinations. Therefore, if an Aa × Aa cross were performed 1000 times, approximately 250 (25 percent) of the offspring would be AA ; 500 (50 percent) would be Aa (that is, Aa plus aA ); and 250 (25 percent) would be aa . The genotypic ratio for this inheritance pattern is 1:2:1. However, we have already established that AA and Aa (and aA ) individuals all express the dominant trait (i.e., share the same phenotype), and can therefore be combined into one group. The result is Mendel’s third-generation phenotype ratio of 3:1. Mendel’s observation of pea plants also included many crosses that involved multiple traits, which prompted him to formulate the principle of independent assortment. The law states that the members of one pair of genes (alleles) from a parent will sort independently from other pairs of genes during the formation of gametes. Applied to pea plants, that means that the alleles associated with the different traits of the plant, such as color, height, or seed type, will sort independently of one another. This holds true except when two alleles happen to be located close to one other on the same chromosome. Independent assortment provides for a great degree of diversity in offspring. Mendelian genetics represent the fundamentals of inheritance, but there are two important qualifiers to consider when applying Mendel’s findings to inheritance studies in humans. First, as we’ve already noted, not all genes are inherited in a dominant–recessive pattern. Although all diploid individuals have two alleles for every gene, allele pairs may interact to create several types of inheritance patterns, including incomplete dominance and codominance. Secondly, Mendel performed his studies using thousands of pea plants. He was able to identify a 3:1 phenotypic ratio in second-generation offspring because his large sample size overcame the influence of variability resulting from chance. In contrast, no human couple has ever had thousands of children. If we know that a man and woman are both heterozygous for a recessive genetic disorder, we would predict that one in every four of their children would be affected by the disease. In real life, however, the influence of chance could change that ratio significantly. For example, if a man and a woman are both heterozygous for cystic fibrosis, a recessive genetic disorder that is expressed only when the individual has two defective alleles, we would expect one in four of their children to have cystic fibrosis. However, it is entirely possible for them to have seven children, none of whom is affected, or for them to have two children, both of whom are affected. For each individual child, the presence or absence of a single gene disorder depends on which alleles that child inherits from his or her parents. Autosomal Dominant Inheritance In the case of cystic fibrosis, the disorder is recessive to the normal phenotype. However, a genetic abnormality may be dominant to the normal phenotype. When the dominant allele is located on one of the 22 pairs of autosomes (non-sex chromosomes), we refer to its inheritance pattern as autosomal dominant . An example of an autosomal dominant disorder is neurofibromatosis type I, a disease that induces tumor formation within the nervous system that leads to skin and skeletal deformities. Consider a couple in which one parent is heterozygous for this disorder (and who therefore has neurofibromatosis), Nn , and one parent is homozygous for the normal gene, nn . The heterozygous parent would have a 50 percent chance of passing the dominant allele for this disorder to his or her offspring, and the homozygous parent would always pass the normal allele. Therefore, four possible offspring genotypes are equally likely to occur: Nn , Nn , nn , and nn . That is, every child of this couple would have a 50 percent chance of inheriting neurofibromatosis. This inheritance pattern is shown in Figure 28.26 , in a form called a Punnett square , named after its creator, the British geneticist Reginald Punnett. Other genetic diseases that are inherited in this pattern are achondroplastic dwarfism, Marfan syndrome, and Huntington’s disease. Because autosomal dominant disorders are expressed by the presence of just one gene, an individual with the disorder will know that he or she has at least one faulty gene. The expression of the disease may manifest later in life, after the childbearing years, which is the case in Huntington’s disease (discussed in more detail later in this section). Autosomal Recessive Inheritance When a genetic disorder is inherited in an autosomal recessive pattern, the disorder corresponds to the recessive phenotype. Heterozygous individuals will not display symptoms of this disorder, because their unaffected gene will compensate. Such an individual is called a carrier . Carriers for an autosomal recessive disorder may never know their genotype unless they have a child with the disorder. An example of an autosomal recessive disorder is cystic fibrosis (CF), which we introduced earlier. CF is characterized by the chronic accumulation of a thick, tenacious mucus in the lungs and digestive tract. Decades ago, children with CF rarely lived to adulthood. With advances in medical technology, the average lifespan in developed countries has increased into middle adulthood. CF is a relatively common disorder that occurs in approximately 1 in 2000 Caucasians. A child born to two CF carriers would have a 25 percent chance of inheriting the disease. This is the same 3:1 dominant:recessive ratio that Mendel observed in his pea plants would apply here. The pattern is shown in Figure 28.27 , using a diagram that tracks the likely incidence of an autosomal recessive disorder on the basis of parental genotypes. On the other hand, a child born to a CF carrier and someone with two unaffected alleles would have a 0 percent probability of inheriting CF, but would have a 50 percent chance of being a carrier. Other examples of autosome recessive genetic illnesses include the blood disorder sickle-cell anemia, the fatal neurological disorder Tay–Sachs disease, and the metabolic disorder phenylketonuria. X-linked Dominant or Recessive Inheritance An X-linked transmission pattern involves genes located on the X chromosome of the 23rd pair ( Figure 28.28 ). Recall that a male has one X and one Y chromosome. When a father transmits a Y chromosome, the child is male, and when he transmits an X chromosome, the child is female. A mother can transmit only an X chromosome, as both her sex chromosomes are X chromosomes. When an abnormal allele for a gene that occurs on the X chromosome is dominant over the normal allele, the pattern is described as X-linked dominant . This is the case with vitamin D–resistant rickets: an affected father would pass the disease gene to all of his daughters, but none of his sons, because he donates only the Y chromosome to his sons (see Figure 28.28 a ). If it is the mother who is affected, all of her children—male or female—would have a 50 percent chance of inheriting the disorder because she can only pass an X chromosome on to her children (see Figure 28.28 b ). For an affected female, the inheritance pattern would be identical to that of an autosomal dominant inheritance pattern in which one parent is heterozygous and the other is homozygous for the normal gene. X-linked recessive inheritance is much more common because females can be carriers of the disease yet still have a normal phenotype. Diseases transmitted by X-linked recessive inheritance include color blindness, the blood-clotting disorder hemophilia, and some forms of muscular dystrophy. For an example of X-linked recessive inheritance, consider parents in which the mother is an unaffected carrier and the father is normal. None of the daughters would have the disease because they receive a normal gene from their father. However, they have a 50 percent chance of receiving the disease gene from their mother and becoming a carrier. In contrast, 50 percent of the sons would be affected ( Figure 28.29 ). With X-linked recessive diseases, males either have the disease or are genotypically normal—they cannot be carriers. Females, however, can be genotypically normal, a carrier who is phenotypically normal, or affected with the disease. A daughter can inherit the gene for an X-linked recessive illness when her mother is a carrier or affected, or her father is affected. The daughter will be affected by the disease only if she inherits an X-linked recessive gene from both parents. As you can imagine, X-linked recessive disorders affect many more males than females. For example, color blindness affects at least 1 in 20 males, but only about 1 in 400 females. Other Inheritance Patterns: Incomplete Dominance, Codominance, and Lethal Alleles Not all genetic disorders are inherited in a dominant–recessive pattern. In incomplete dominance , the offspring express a heterozygous phenotype that is intermediate between one parent’s homozygous dominant trait and the other parent’s homozygous recessive trait. An example of this can be seen in snapdragons when red-flowered plants and white-flowered plants are crossed to produce pink-flowered plants. In humans, incomplete dominance occurs with one of the genes for hair texture. When one parent passes a curly hair allele (the incompletely dominant allele) and the other parent passes a straight-hair allele, the effect on the offspring will be intermediate, resulting in hair that is wavy. Codominance is characterized by the equal, distinct, and simultaneous expression of both parents’ different alleles. This pattern differs from the intermediate, blended features seen in incomplete dominance. A classic example of codominance in humans is ABO blood type. People are blood type A if they have an allele for an enzyme that facilitates the production of surface antigen A on their erythrocytes. This allele is designated I A . In the same manner, people are blood type B if they express an enzyme for the production of surface antigen B. People who have alleles for both enzymes ( I A and I B ) produce both surface antigens A and B. As a result, they are blood type AB. Because the effect of both alleles (or enzymes) is observed, we say that the I A and I B alleles are codominant. There is also a third allele that determines blood type. This allele ( i ) produces a nonfunctional enzyme. People who have two i alleles do not produce either A or B surface antigens: they have type O blood. If a person has I A and i alleles, the person will have blood type A. Notice that it does not make any difference whether a person has two I A alleles or one I A and one i allele. In both cases, the person is blood type A. Because I A masks i , we say that I A is dominant to i . Table 28.4 summarizes the expression of blood type. Expression of Blood Types Blood type Genotype Pattern of inheritance A I A I A or I A i I A is dominant to i B I B I B or I B i I B is dominant to i AB I A I B I A is co-dominant to I B O ii Two recessive alleles Table 28.4 Certain combinations of alleles can be lethal, meaning they prevent the individual from developing in utero, or cause a shortened life span. In recessive lethal inheritance patterns, a child who is born to two heterozygous (carrier) parents and who inherited the faulty allele from both would not survive. An example of this is Tay–Sachs, a fatal disorder of the nervous system. In this disorder, parents with one copy of the allele for the disorder are carriers. If they both transmit their abnormal allele, their offspring will develop the disease and will die in childhood, usually before age 5. Dominant lethal inheritance patterns are much more rare because neither heterozygotes nor homozygotes survive. Of course, dominant lethal alleles that arise naturally through mutation and cause miscarriages or stillbirths are never transmitted to subsequent generations. However, some dominant lethal alleles, such as the allele for Huntington’s disease, cause a shortened life span but may not be identified until after the person reaches reproductive age and has children. Huntington’s disease causes irreversible nerve cell degeneration and death in 100 percent of affected individuals, but it may not be expressed until the individual reaches middle age. In this way, dominant lethal alleles can be maintained in the human population. Individuals with a family history of Huntington’s disease are typically offered genetic counseling, which can help them decide whether or not they wish to be tested for the faulty gene. Mutations A mutation is a change in the sequence of DNA nucleotides that may or may not affect a person’s phenotype. Mutations can arise spontaneously from errors during DNA replication, or they can result from environmental insults such as radiation, certain viruses, or exposure to tobacco smoke or other toxic chemicals. Because genes encode for the assembly of proteins, a mutation in the nucleotide sequence of a gene can change amino acid sequence and, consequently, a protein’s structure and function. Spontaneous mutations occurring during meiosis are thought to account for many spontaneous abortions (miscarriages). Chromosomal Disorders Sometimes a genetic disease is not caused by a mutation in a gene, but by the presence of an incorrect number of chromosomes. For example, Down syndrome is caused by having three copies of chromosome 21. This is known as trisomy 21. The most common cause of trisomy 21 is chromosomal nondisjunction during meiosis. The frequency of nondisjunction events appears to increase with age, so the frequency of bearing a child with Down syndrome increases in women over 36. The age of the father matters less because nondisjunction is much less likely to occur in a sperm than in an egg. Whereas Down syndrome is caused by having three copies of a chromosome, Turner syndrome is caused by having just one copy of the X chromosome. This is known as monosomy. The affected child is always female. Women with Turner syndrome are sterile because their sexual organs do not mature. Career Connection Genetic Counselor Given the intricate orchestration of gene expression, cell migration, and cell differentiation during prenatal development, it is amazing that the vast majority of newborns are healthy and free of major birth defects. When a woman over 35 is pregnant or intends to become pregnant, or her partner is over 55, or if there is a family history of a genetic disorder, she and her partner may want to speak to a genetic counselor to discuss the likelihood that their child may be affected by a genetic or chromosomal disorder. A genetic counselor can interpret a couple’s family history and estimate the risks to their future offspring. For many genetic diseases, a DNA test can determine whether a person is a carrier. For instance, carrier status for Fragile X, an X-linked disorder associated with mental retardation, or for cystic fibrosis can be determined with a simple blood draw to obtain DNA for testing. A genetic counselor can educate a couple about the implications of such a test and help them decide whether to undergo testing. For chromosomal disorders, the available testing options include a blood test, amniocentesis (in which amniotic fluid is tested), and chorionic villus sampling (in which tissue from the placenta is tested). Each of these has advantages and drawbacks. A genetic counselor can also help a couple cope with the news that either one or both partners is a carrier of a genetic illness, or that their unborn child has been diagnosed with a chromosomal disorder or other birth defect. To become a genetic counselor, one needs to complete a 4-year undergraduate program and then obtain a Master of Science in Genetic Counseling from an accredited university. Board certification is attained after passing examinations by the American Board of Genetic Counseling. Genetic counselors are essential professionals in many branches of medicine, but there is a particular demand for preconception and prenatal genetic counselors. Interactive Link Visit the National Society of Genetic Counselors website for more information about genetic counselors. Interactive Link Visit the American Board of Genetic Counselors, Inc., website for more information about genetic counselors.
biology
Chapter Outline 40.1 Overview of the Circulatory System 40.2 Components of the Blood 40.3 Mammalian Heart and Blood Vessels 40.4 Blood Flow and Blood Pressure Regulation Introduction Most animals are complex multicellular organisms that require a mechanism for transporting nutrients throughout their bodies and removing waste products. The circulatory system has evolved over time from simple diffusion through cells in the early evolution of animals to a complex network of blood vessels that reach all parts of the human body. This extensive network supplies the cells, tissues, and organs with oxygen and nutrients, and removes carbon dioxide and waste, which are byproducts of respiration. At the core of the human circulatory system is the heart. The size of a clenched fist, the human heart is protected beneath the rib cage. Made of specialized and unique cardiac muscle, it pumps blood throughout the body and to the heart itself. Heart contractions are driven by intrinsic electrical impulses that the brain and endocrine hormones help to regulate. Understanding the heart’s basic anatomy and function is important to understanding the body’s circulatory and respiratory systems. Gas exchange is one essential function of the circulatory system. A circulatory system is not needed in organisms with no specialized respiratory organs because oxygen and carbon dioxide diffuse directly between their body tissues and the external environment. However, in organisms that possess lungs and gills, oxygen must be transported from these specialized respiratory organs to the body tissues via a circulatory system. Therefore, circulatory systems have had to evolve to accommodate the great diversity of body sizes and body types present among animals.
[ { "answer": { "ans_choice": 0, "ans_text": "They use less metabolic energy." }, "bloom": null, "hl_context": "The circulatory system is effectively a network of cylindrical vessels : the arteries , veins , and capillaries that emanate from a pump , the heart . In all vertebrate organisms , as well as some invertebrates , this is a closed-loop system , in which the blood is not free in a cavity . In a closed circulatory system , blood is contained inside blood vessels and circulates unidirectionally from the heart around the systemic circulatory route , then returns to the heart again , as illustrated in Figure 40.2 a . As opposed to a closed system , arthropods — including insects , crustaceans , and most mollusks — have an open circulatory system , as illustrated in Figure 40.2 b . In an open circulatory system , the blood is not enclosed in the blood vessels but is pumped into a cavity called a hemocoel and is called hemolymph because the blood mixes with the interstitial fluid . As the heart beats and the animal moves , the hemolymph circulates around the organs within the body cavity and then reenters the hearts through openings called ostia . This movement allows for gas and nutrient exchange . <hl> An open circulatory system does not use as much energy as a closed system to operate or to maintain ; however , there is a trade-off with the amount of blood that can be moved to metabolically active organs and tissues that require high levels of oxygen . <hl> In fact , one reason that insects with wing spans of up to two feet wide ( 70 cm ) are not around today is probably because they were outcompeted by the arrival of birds 150 million years ago . Birds , having a closed circulatory system , are thought to have moved more agilely , allowing them to get food faster and possibly to prey on the insects .", "hl_sentences": "An open circulatory system does not use as much energy as a closed system to operate or to maintain ; however , there is a trade-off with the amount of blood that can be moved to metabolically active organs and tissues that require high levels of oxygen .", "question": { "cloze_format": "The reason open circulatory systems are advantageous to some animals is that ___ .", "normal_format": "Why are open circulatory systems advantageous to some animals?", "question_choices": [ "They use less metabolic energy.", "They help the animal move faster.", "They do not need a heart.", "They help large insects develop." ], "question_id": "fs-idm300553744", "question_text": "Why are open circulatory systems advantageous to some animals?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 3, "ans_text": "None of the above" }, "bloom": null, "hl_context": "The circulatory system varies from simple systems in invertebrates to more complex systems in vertebrates . <hl> The simplest animals , such as the sponges ( Porifera ) and rotifers ( Rotifera ) , do not need a circulatory system because diffusion allows adequate exchange of water , nutrients , and waste , as well as dissolved gases , as shown in Figure 40.3 a . <hl> Organisms that are more complex but still only have two layers of cells in their body plan , such as jellies ( Cnidaria ) and comb jellies ( Ctenophora ) also use diffusion through their epidermis and internally through the gastrovascular compartment . Both their internal and external tissues are bathed in an aqueous environment and exchange fluids by diffusion on both sides , as illustrated in Figure 40.3 b . Exchange of fluids is assisted by the pulsing of the jellyfish body . For more complex organisms , diffusion is not efficient for cycling gases , nutrients , and waste effectively through the body ; therefore , more complex circulatory systems evolved . Most arthropods and many mollusks have open circulatory systems . In an open system , an elongated beating heart pushes the hemolymph through the body and muscle contractions help to move fluids . The larger more complex crustaceans , including lobsters , have developed arterial-like vessels to push blood through their bodies , and the most active mollusks , such as squids , have evolved a closed circulatory system and are able to move rapidly to catch prey . Closed circulatory systems are a characteristic of vertebrates ; however , there are significant differences in the structure of the heart and the circulation of blood between the different vertebrate groups due to adaptation during evolution and associated differences in anatomy . Figure 40.4 illustrates the basic circulatory systems of some vertebrates : fish , amphibians , reptiles , and mammals . As illustrated in Figure 40.4 a Fish have a single circuit for blood flow and a two-chambered heart that has only a single atrium and a single ventricle . The atrium collects blood that has returned from the body and the ventricle pumps the blood to the gills where gas exchange occurs and the blood is re-oxygenated ; this is called gill circulation . The blood then continues through the rest of the body before arriving back at the atrium ; this is called systemic circulation . This unidirectional flow of blood produces a gradient of oxygenated to deoxygenated blood around the fish ’ s systemic circuit . The result is a limit in the amount of oxygen that can reach some of the organs and tissues of the body , reducing the overall metabolic capacity of fish . In amphibians , reptiles , birds , and mammals , blood flow is directed in two circuits : one through the lungs and back to the heart , which is called pulmonary circulation , and the other throughout the rest of the body and its organs including the brain ( systemic circulation ) . In amphibians , gas exchange also occurs through the skin during pulmonary circulation and is referred to as pulmocutaneous circulation . Chapter Outline 40.1 Overview of the Circulatory System 40.2 Components of the Blood 40.3 Mammalian Heart and Blood Vessels 40.4 Blood Flow and Blood Pressure Regulation Introduction Most animals are complex multicellular organisms that require a mechanism for transporting nutrients throughout their bodies and removing waste products . <hl> The circulatory system has evolved over time from simple diffusion through cells in the early evolution of animals to a complex network of blood vessels that reach all parts of the human body . <hl> This extensive network supplies the cells , tissues , and organs with oxygen and nutrients , and removes carbon dioxide and waste , which are byproducts of respiration . At the core of the human circulatory system is the heart . The size of a clenched fist , the human heart is protected beneath the rib cage . Made of specialized and unique cardiac muscle , it pumps blood throughout the body and to the heart itself . Heart contractions are driven by intrinsic electrical impulses that the brain and endocrine hormones help to regulate . Understanding the heart ’ s basic anatomy and function is important to understanding the body ’ s circulatory and respiratory systems . Gas exchange is one essential function of the circulatory system . A circulatory system is not needed in organisms with no specialized respiratory organs because oxygen and carbon dioxide diffuse directly between their body tissues and the external environment . However , in organisms that possess lungs and gills , oxygen must be transported from these specialized respiratory organs to the body tissues via a circulatory system . Therefore , circulatory systems have had to evolve to accommodate the great diversity of body sizes and body types present among animals .", "hl_sentences": "The simplest animals , such as the sponges ( Porifera ) and rotifers ( Rotifera ) , do not need a circulatory system because diffusion allows adequate exchange of water , nutrients , and waste , as well as dissolved gases , as shown in Figure 40.3 a . The circulatory system has evolved over time from simple diffusion through cells in the early evolution of animals to a complex network of blood vessels that reach all parts of the human body .", "question": { "cloze_format": "Some animals use diffusion instead of a circulatory system. Examples include ___.", "normal_format": "What is an example of an animal that uses diffusion instead of a circulatory system?", "question_choices": [ "birds and jellyfish", "flatworms and arthropods", "mollusks and jellyfish", "None of the above" ], "question_id": "fs-idm216101712", "question_text": "Some animals use diffusion instead of a circulatory system. Examples include:" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 2, "ans_text": "pulmonary circulation" }, "bloom": null, "hl_context": "The circulatory system varies from simple systems in invertebrates to more complex systems in vertebrates . The simplest animals , such as the sponges ( Porifera ) and rotifers ( Rotifera ) , do not need a circulatory system because diffusion allows adequate exchange of water , nutrients , and waste , as well as dissolved gases , as shown in Figure 40.3 a . Organisms that are more complex but still only have two layers of cells in their body plan , such as jellies ( Cnidaria ) and comb jellies ( Ctenophora ) also use diffusion through their epidermis and internally through the gastrovascular compartment . Both their internal and external tissues are bathed in an aqueous environment and exchange fluids by diffusion on both sides , as illustrated in Figure 40.3 b . Exchange of fluids is assisted by the pulsing of the jellyfish body . For more complex organisms , diffusion is not efficient for cycling gases , nutrients , and waste effectively through the body ; therefore , more complex circulatory systems evolved . Most arthropods and many mollusks have open circulatory systems . In an open system , an elongated beating heart pushes the hemolymph through the body and muscle contractions help to move fluids . The larger more complex crustaceans , including lobsters , have developed arterial-like vessels to push blood through their bodies , and the most active mollusks , such as squids , have evolved a closed circulatory system and are able to move rapidly to catch prey . Closed circulatory systems are a characteristic of vertebrates ; however , there are significant differences in the structure of the heart and the circulation of blood between the different vertebrate groups due to adaptation during evolution and associated differences in anatomy . Figure 40.4 illustrates the basic circulatory systems of some vertebrates : fish , amphibians , reptiles , and mammals . As illustrated in Figure 40.4 a Fish have a single circuit for blood flow and a two-chambered heart that has only a single atrium and a single ventricle . The atrium collects blood that has returned from the body and the ventricle pumps the blood to the gills where gas exchange occurs and the blood is re-oxygenated ; this is called gill circulation . The blood then continues through the rest of the body before arriving back at the atrium ; this is called systemic circulation . This unidirectional flow of blood produces a gradient of oxygenated to deoxygenated blood around the fish ’ s systemic circuit . The result is a limit in the amount of oxygen that can reach some of the organs and tissues of the body , reducing the overall metabolic capacity of fish . <hl> In amphibians , reptiles , birds , and mammals , blood flow is directed in two circuits : one through the lungs and back to the heart , which is called pulmonary circulation , and the other throughout the rest of the body and its organs including the brain ( systemic circulation ) . <hl> In amphibians , gas exchange also occurs through the skin during pulmonary circulation and is referred to as pulmocutaneous circulation .", "hl_sentences": "In amphibians , reptiles , birds , and mammals , blood flow is directed in two circuits : one through the lungs and back to the heart , which is called pulmonary circulation , and the other throughout the rest of the body and its organs including the brain ( systemic circulation ) .", "question": { "cloze_format": "Blood flow that is directed through the lungs and back to the heart is called ________.", "normal_format": "What is blood flow called that is directed through the lungs and back to the heart?", "question_choices": [ "unidirectional circulation", "gill circulation", "pulmonary circulation", "pulmocutaneous circulation" ], "question_id": "fs-idm225583056", "question_text": "Blood flow that is directed through the lungs and back to the heart is called ________." }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 3, "ans_text": "All of the above" }, "bloom": null, "hl_context": "The morphology of white blood cells differs significantly from red blood cells . They have nuclei and do not contain hemoglobin . The different types of white blood cells are identified by their microscopic appearance after histologic staining , and each has a different specialized function . <hl> The two main groups , both illustrated in Figure 40.7 are the granulocytes , which include the neutrophils , eosinophils , and basophils , and the agranulocytes , which include the monocytes and lymphocytes . <hl> <hl> White blood cells , also called leukocytes ( leuko = white ) , make up approximately one percent by volume of the cells in blood . <hl> <hl> The role of white blood cells is very different than that of red blood cells : they are primarily involved in the immune response to identify and target pathogens , such as invading bacteria , viruses , and other foreign organisms . <hl> White blood cells are formed continually ; some only live for hours or days , but some live for years .", "hl_sentences": "The two main groups , both illustrated in Figure 40.7 are the granulocytes , which include the neutrophils , eosinophils , and basophils , and the agranulocytes , which include the monocytes and lymphocytes . White blood cells , also called leukocytes ( leuko = white ) , make up approximately one percent by volume of the cells in blood . The role of white blood cells is very different than that of red blood cells : they are primarily involved in the immune response to identify and target pathogens , such as invading bacteria , viruses , and other foreign organisms .", "question": { "cloze_format": "White blood cells ___ .", "normal_format": "White blood cells are what?", "question_choices": [ "can be classified as granulocytes or agranulocytes", "defend the body against bacteria and viruses", "are also called leucocytes", "All of the above" ], "question_id": "fs-idm6200624", "question_text": "White blood cells:" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 2, "ans_text": "when platelets are attracted to a site of blood vessel damage" }, "bloom": null, "hl_context": "Blood must clot to heal wounds and prevent excess blood loss . <hl> Small cell fragments called platelets ( thrombocytes ) are attracted to the wound site where they adhere by extending many projections and releasing their contents . <hl> These contents activate other platelets and also interact with other coagulation factors , which convert fibrinogen , a water-soluble protein present in blood serum into fibrin ( a non-water soluble protein ) , causing the blood to clot . Many of the clotting factors require vitamin K to work , and vitamin K deficiency can lead to problems with blood clotting . <hl> Many platelets converge and stick together at the wound site forming a platelet plug ( also called a fibrin clot ) , as illustrated in Figure 40.8 b . <hl> The plug or clot lasts for a number of days and stops the loss of blood . Platelets are formed from the disintegration of larger cells called megakaryocytes , like that shown in Figure 40.8 a . For each megakaryocyte , 2000 – 3000 platelets are formed with 150,000 to 400,000 platelets present in each cubic millimeter of blood . Each platelet is disc shaped and 2 – 4 μm in diameter . They contain many small vesicles but do not contain a nucleus .", "hl_sentences": "Small cell fragments called platelets ( thrombocytes ) are attracted to the wound site where they adhere by extending many projections and releasing their contents . Many platelets converge and stick together at the wound site forming a platelet plug ( also called a fibrin clot ) , as illustrated in Figure 40.8 b .", "question": { "cloze_format": "The point at which platelet plug formation occurs is ___ .", "normal_format": "Platelet plug formation occurs at which point?", "question_choices": [ "when large megakaryocytes break up into thousands of smaller fragments", "when platelets are dispersed through the blood stream", "when platelets are attracted to a site of blood vessel damage", "none of the above" ], "question_id": "fs-idm26244160", "question_text": "Platelet plug formation occurs at which point?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 2, "ans_text": "25 percent" }, "bloom": null, "hl_context": "Hemoglobin is responsible for distributing oxygen , and to a lesser extent , carbon dioxide , throughout the circulatory systems of humans , vertebrates , and many invertebrates . The blood is more than the proteins , though . Blood is actually a term used to describe the liquid that moves through the vessels and includes plasma ( the liquid portion , which contains water , proteins , salts , lipids , and glucose ) and the cells ( red and white cells ) and cell fragments called platelets . Blood plasma is actually the dominant component of blood and contains the water , proteins , electrolytes , lipids , and glucose . The cells are responsible for carrying the gases ( red cells ) and immune the response ( white ) . The platelets are responsible for blood clotting . Interstitial fluid that surrounds cells is separate from the blood , but in hemolymph , they are combined . <hl> In humans , cellular components make up approximately 45 percent of the blood and the liquid plasma 55 percent . <hl> Blood is 20 percent of a person ’ s extracellular fluid and eight percent of weight . The Role of Blood in the Body", "hl_sentences": "In humans , cellular components make up approximately 45 percent of the blood and the liquid plasma 55 percent .", "question": { "cloze_format": "In humans, the plasma comprises a percentage of ___ of the blood.", "normal_format": "In humans, the plasma comprises what percentage of the blood?", "question_choices": [ "45 percent", "55 percent", "25 percent", "90 percent" ], "question_id": "fs-idm67048352", "question_text": "In humans, the plasma comprises what percentage of the blood?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 2, "ans_text": "they have nuclei" }, "bloom": null, "hl_context": "Red blood cells , or erythrocytes ( erythro - = “ red ” ; - cyte = “ cell ” ) , are specialized cells that circulate through the body delivering oxygen to cells ; they are formed from stem cells in the bone marrow . In mammals , red blood cells are small biconcave cells that at maturity do not contain a nucleus or mitochondria and are only 7 – 8 µm in size . <hl> In birds and non-avian reptiles , a nucleus is still maintained in red blood cells . <hl> The red coloring of blood comes from the iron-containing protein hemoglobin , illustrated in Figure 40.6 a . The principal job of this protein is to carry oxygen , but it also transports carbon dioxide as well . Hemoglobin is packed into red blood cells at a rate of about 250 million molecules of hemoglobin per cell . Each hemoglobin molecule binds four oxygen molecules so that each red blood cell carries one billion molecules of oxygen . There are approximately 25 trillion red blood cells in the five liters of blood in the human body , which could carry up to 25 sextillion ( 25 × 10 21 ) molecules of oxygen in the body at any time . In mammals , the lack of organelles in erythrocytes leaves more room for the hemoglobin molecules , and the lack of mitochondria also prevents use of the oxygen for metabolic respiration . Only mammals have anucleated red blood cells , and some mammals ( camels , for instance ) even have nucleated red blood cells . The advantage of nucleated red blood cells is that these cells can undergo mitosis . Anucleated red blood cells metabolize anaerobically ( without oxygen ) , making use of a primitive metabolic pathway to produce ATP and increase the efficiency of oxygen transport .", "hl_sentences": "In birds and non-avian reptiles , a nucleus is still maintained in red blood cells .", "question": { "cloze_format": "The red blood cells of birds differ from mammalian red blood cells because ___ .", "normal_format": "Why do the red blood cells of birds differ from mammalian red blood cells?", "question_choices": [ "they are white and have nuclei", "they do not have nuclei", "they have nuclei", "they fight disease" ], "question_id": "fs-idm93132096", "question_text": "The red blood cells of birds differ from mammalian red blood cells because:" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 1, "ans_text": "the excitation of cardiac muscle cells at the sinoatrial node followed by the atrioventricular node" }, "bloom": null, "hl_context": "<hl> The autonomous beating of cardiac muscle cells is regulated by the heart ’ s internal pacemaker that uses electrical signals to time the beating of the heart . <hl> The electrical signals and mechanical actions , illustrated in Figure 40.14 , are intimately intertwined . The internal pacemaker starts at the sinoatrial ( SA ) node , which is located near the wall of the right atrium . Electrical charges spontaneously pulse from the SA node causing the two atria to contract in unison . The pulse reaches a second node , called the atrioventricular ( AV ) node , between the right atrium and right ventricle where it pauses for approximately 0.1 second before spreading to the walls of the ventricles . From the AV node , the electrical impulse enters the bundle of His , then to the left and right bundle branches extending through the interventricular septum . Finally , the Purkinje fibers conduct the impulse from the apex of the heart up the ventricular myocardium , and then the ventricles contract . This pause allows the atria to empty completely into the ventricles before the ventricles pump out the blood . The electrical impulses in the heart produce electrical currents that flow through the body and can be measured on the skin using electrodes . This information can be observed as an electrocardiogram ( ECG ) — a recording of the electrical impulses of the cardiac muscle . <hl> The pumping of the heart is a function of the cardiac muscle cells , or cardiomyocytes , that make up the heart muscle . <hl> Cardiomyocytes , shown in Figure 40.13 , are distinctive muscle cells that are striated like skeletal muscle but pump rhythmically and involuntarily like smooth muscle ; they are connected by intercalated disks exclusive to cardiac muscle . They are self-stimulated for a period of time and isolated cardiomyocytes will beat if given the correct balance of nutrients and electrolytes .", "hl_sentences": "The autonomous beating of cardiac muscle cells is regulated by the heart ’ s internal pacemaker that uses electrical signals to time the beating of the heart . The pumping of the heart is a function of the cardiac muscle cells , or cardiomyocytes , that make up the heart muscle .", "question": { "cloze_format": "The heart’s internal pacemaker beats by ___.", "normal_format": "How does the heart’s internal pacemaker beat by?", "question_choices": [ "an internal implant that sends an electrical impulse through the heart", "the excitation of cardiac muscle cells at the sinoatrial node followed by the atrioventricular node", "the excitation of cardiac muscle cells at the atrioventricular node followed by the sinoatrial node", "the action of the sinus" ], "question_id": "fs-idp26179632", "question_text": "The heart’s internal pacemaker beats by:" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 0, "ans_text": "contracting" }, "bloom": null, "hl_context": "The main purpose of the heart is to pump blood through the body ; it does so in a repeating sequence called the cardiac cycle . The cardiac cycle is the coordination of the filling and emptying of the heart of blood by electrical signals that cause the heart muscles to contract and relax . The human heart beats over 100,000 times per day . <hl> In each cardiac cycle , the heart contracts ( systole ) , pushing out the blood and pumping it through the body ; this is followed by a relaxation phase ( diastole ) , where the heart fills with blood , as illustrated in Figure 40.12 . <hl> The atria contract at the same time , forcing blood through the atrioventricular valves into the ventricles . Closing of the atrioventricular valves produces a monosyllabic “ lup ” sound . Following a brief delay , the ventricles contract at the same time forcing blood through the semilunar valves into the aorta and the artery transporting blood to the lungs ( via the pulmonary artery ) . Closing of the semilunar valves produces a monosyllabic “ dup ” sound .", "hl_sentences": "In each cardiac cycle , the heart contracts ( systole ) , pushing out the blood and pumping it through the body ; this is followed by a relaxation phase ( diastole ) , where the heart fills with blood , as illustrated in Figure 40.12 .", "question": { "cloze_format": "During the systolic phase of the cardiac cycle, the heart is ________.", "normal_format": "During the systolic phase of the cardiac cycle, what is the heart doing?", "question_choices": [ "contracting", "relaxing", "contracting and relaxing", "filling with blood" ], "question_id": "fs-idm153328976", "question_text": "During the systolic phase of the cardiac cycle, the heart is ________." }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 3, "ans_text": "they are striated" }, "bloom": null, "hl_context": "The pumping of the heart is a function of the cardiac muscle cells , or cardiomyocytes , that make up the heart muscle . <hl> Cardiomyocytes , shown in Figure 40.13 , are distinctive muscle cells that are striated like skeletal muscle but pump rhythmically and involuntarily like smooth muscle ; they are connected by intercalated disks exclusive to cardiac muscle . <hl> They are self-stimulated for a period of time and isolated cardiomyocytes will beat if given the correct balance of nutrients and electrolytes .", "hl_sentences": "Cardiomyocytes , shown in Figure 40.13 , are distinctive muscle cells that are striated like skeletal muscle but pump rhythmically and involuntarily like smooth muscle ; they are connected by intercalated disks exclusive to cardiac muscle .", "question": { "cloze_format": "Cardiomyocytes are similar to skeletal muscle because ___ .", "normal_format": "Why are cardiomyocytes similar to skeletal muscle?", "question_choices": [ "they beat involuntarily", "they are used for weight lifting", "they pulse rhythmically", "they are striated" ], "question_id": "fs-idm232681600", "question_text": "Cardiomyocytes are similar to skeletal muscle because:" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 0, "ans_text": "Arteries have thicker smooth muscle layers to accommodate the changes in pressure from the heart." }, "bloom": "2", "hl_context": "Veins and arteries both have two further tunics that surround the endothelium : the middle tunic is composed of smooth muscle and the outermost layer is connective tissue ( collagen and elastic fibers ) . The elastic connective tissue stretches and supports the blood vessels , and the smooth muscle layer helps regulate blood flow by altering vascular resistance through vasoconstriction and vasodilation . <hl> The arteries have thicker smooth muscle and connective tissue than the veins to accommodate the higher pressure and speed of freshly pumped blood . <hl> The veins are thinner walled as the pressure and rate of flow are much lower . In addition , veins are structurally different than arteries in that veins have valves to prevent the backflow of blood . Because veins have to work against gravity to get blood back to the heart , contraction of skeletal muscle assists with the flow of blood back to the heart . 40.4 Blood Flow and Blood Pressure Regulation Learning Objectives By the end of this section , you will be able to :", "hl_sentences": "The arteries have thicker smooth muscle and connective tissue than the veins to accommodate the higher pressure and speed of freshly pumped blood .", "question": { "cloze_format": "Arteries differ from veins because ___.", "normal_format": "How do arteries differ from veins?", "question_choices": [ "Arteries have thicker smooth muscle layers to accommodate the changes in pressure from the heart.", "Arteries carry blood.", "Arteries have thinner smooth muscle layers and valves and move blood by the action of skeletal muscle.", "Arteries are thin walled and are used for gas exchange." ], "question_id": "fs-idm25699712", "question_text": "How do arteries differ from veins?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 0, "ans_text": "a high cardiac output and high peripheral resistance" }, "bloom": null, "hl_context": "Cardiac output is the volume of blood pumped by the heart in one minute . It is calculated by multiplying the number of heart contractions that occur per minute ( heart rate ) times the stroke volume ( the volume of blood pumped into the aorta per contraction of the left ventricle ) . Therefore , cardiac output can be increased by increasing heart rate , as when exercising . However , cardiac output can also be increased by increasing stroke volume , such as if the heart contracts with greater strength . Stroke volume can also be increased by speeding blood circulation through the body so that more blood enters the heart between contractions . During heavy exertion , the blood vessels relax and increase in diameter , offsetting the increased heart rate and ensuring adequate oxygenated blood gets to the muscles . <hl> Stress triggers a decrease in the diameter of the blood vessels , consequently increasing blood pressure . <hl> <hl> These changes can also be caused by nerve signals or hormones , and even standing up or lying down can have a great effect on blood pressure . <hl> The pressure of the blood flow in the body is produced by the hydrostatic pressure of the fluid ( blood ) against the walls of the blood vessels . Fluid will move from areas of high to low hydrostatic pressures . In the arteries , the hydrostatic pressure near the heart is very high and blood flows to the arterioles where the rate of flow is slowed by the narrow openings of the arterioles . During systole , when new blood is entering the arteries , the artery walls stretch to accommodate the increase of pressure of the extra blood ; during diastole , the walls return to normal because of their elastic properties . The blood pressure of the systole phase and the diastole phase , graphed in Figure 40.19 , gives the two pressure readings for blood pressure . For example , 120/80 indicates a reading of 120 mm Hg during the systole and 80 mm Hg during diastole . Throughout the cardiac cycle , the blood continues to empty into the arterioles at a relatively even rate . <hl> This resistance to blood flow is called peripheral resistance . <hl> Long necked animals , such as giraffes , need to pump blood upward from the heart against gravity . The blood pressure required from the pumping of the left ventricle would be equivalent to 250 mm Hg ( mm Hg = millimeters of mercury , a unit of pressure ) to reach the height of a giraffe ’ s head , which is 2.5 meters higher than the heart . However , if checks and balances were not in place , this blood pressure would damage the giraffe ’ s brain , particularly if it was bending down to drink . <hl> These checks and balances include valves and feedback mechanisms that reduce the rate of cardiac output . <hl> Long-necked dinosaurs such as the sauropods had to pump blood even higher , up to ten meters above the heart . This would have required a blood pressure of more than 600 mm Hg , which could only have been achieved by an enormous heart . Evidence for such an enormous heart does not exist and mechanisms to reduce the blood pressure required include the slowing of metabolism as these animals grew larger . It is likely that they did not routinely feed on tree tops but grazed on the ground .", "hl_sentences": "Stress triggers a decrease in the diameter of the blood vessels , consequently increasing blood pressure . These changes can also be caused by nerve signals or hormones , and even standing up or lying down can have a great effect on blood pressure . This resistance to blood flow is called peripheral resistance . These checks and balances include valves and feedback mechanisms that reduce the rate of cardiac output .", "question": { "cloze_format": "High blood pressure would be a result of ________.", "normal_format": "What would high blood pressure be a result of?", "question_choices": [ "a high cardiac output and high peripheral resistance", "a high cardiac output and low peripheral resistance", "a low cardiac output and high peripheral resistance", "a low cardiac output and low peripheral resistance" ], "question_id": "fs-idm95376912", "question_text": "High blood pressure would be a result of ________." }, "references_are_paraphrase": null } ]
40
40.1 Overview of the Circulatory System Learning Objectives By the end of this section, you will be able to: Describe an open and closed circulatory system Describe interstitial fluid and hemolymph Compare and contrast the organization and evolution of the vertebrate circulatory system. In all animals, except a few simple types, the circulatory system is used to transport nutrients and gases through the body. Simple diffusion allows some water, nutrient, waste, and gas exchange into primitive animals that are only a few cell layers thick; however, bulk flow is the only method by which the entire body of larger more complex organisms is accessed. Circulatory System Architecture The circulatory system is effectively a network of cylindrical vessels: the arteries, veins, and capillaries that emanate from a pump, the heart. In all vertebrate organisms, as well as some invertebrates, this is a closed-loop system, in which the blood is not free in a cavity. In a closed circulatory system , blood is contained inside blood vessels and circulates unidirectionally from the heart around the systemic circulatory route, then returns to the heart again, as illustrated in Figure 40.2 a . As opposed to a closed system, arthropods—including insects, crustaceans, and most mollusks—have an open circulatory system, as illustrated in Figure 40.2 b . In an open circulatory system , the blood is not enclosed in the blood vessels but is pumped into a cavity called a hemocoel and is called hemolymph because the blood mixes with the interstitial fluid . As the heart beats and the animal moves, the hemolymph circulates around the organs within the body cavity and then reenters the hearts through openings called ostia . This movement allows for gas and nutrient exchange. An open circulatory system does not use as much energy as a closed system to operate or to maintain; however, there is a trade-off with the amount of blood that can be moved to metabolically active organs and tissues that require high levels of oxygen. In fact, one reason that insects with wing spans of up to two feet wide (70 cm) are not around today is probably because they were outcompeted by the arrival of birds 150 million years ago. Birds, having a closed circulatory system, are thought to have moved more agilely, allowing them to get food faster and possibly to prey on the insects. Circulatory System Variation in Animals The circulatory system varies from simple systems in invertebrates to more complex systems in vertebrates. The simplest animals, such as the sponges (Porifera) and rotifers (Rotifera), do not need a circulatory system because diffusion allows adequate exchange of water, nutrients, and waste, as well as dissolved gases, as shown in Figure 40.3 a . Organisms that are more complex but still only have two layers of cells in their body plan, such as jellies (Cnidaria) and comb jellies (Ctenophora) also use diffusion through their epidermis and internally through the gastrovascular compartment. Both their internal and external tissues are bathed in an aqueous environment and exchange fluids by diffusion on both sides, as illustrated in Figure 40.3 b . Exchange of fluids is assisted by the pulsing of the jellyfish body. For more complex organisms, diffusion is not efficient for cycling gases, nutrients, and waste effectively through the body; therefore, more complex circulatory systems evolved. Most arthropods and many mollusks have open circulatory systems. In an open system, an elongated beating heart pushes the hemolymph through the body and muscle contractions help to move fluids. The larger more complex crustaceans, including lobsters, have developed arterial-like vessels to push blood through their bodies, and the most active mollusks, such as squids, have evolved a closed circulatory system and are able to move rapidly to catch prey. Closed circulatory systems are a characteristic of vertebrates; however, there are significant differences in the structure of the heart and the circulation of blood between the different vertebrate groups due to adaptation during evolution and associated differences in anatomy. Figure 40.4 illustrates the basic circulatory systems of some vertebrates: fish, amphibians, reptiles, and mammals. As illustrated in Figure 40.4 a Fish have a single circuit for blood flow and a two-chambered heart that has only a single atrium and a single ventricle. The atrium collects blood that has returned from the body and the ventricle pumps the blood to the gills where gas exchange occurs and the blood is re-oxygenated; this is called gill circulation . The blood then continues through the rest of the body before arriving back at the atrium; this is called systemic circulation . This unidirectional flow of blood produces a gradient of oxygenated to deoxygenated blood around the fish’s systemic circuit. The result is a limit in the amount of oxygen that can reach some of the organs and tissues of the body, reducing the overall metabolic capacity of fish. In amphibians, reptiles, birds, and mammals, blood flow is directed in two circuits: one through the lungs and back to the heart, which is called pulmonary circulation , and the other throughout the rest of the body and its organs including the brain (systemic circulation). In amphibians, gas exchange also occurs through the skin during pulmonary circulation and is referred to as pulmocutaneous circulation . As shown in Figure 40.4 b , amphibians have a three-chambered heart that has two atria and one ventricle rather than the two-chambered heart of fish. The two atria (superior heart chambers) receive blood from the two different circuits (the lungs and the systems), and then there is some mixing of the blood in the heart’s ventricle (inferior heart chamber), which reduces the efficiency of oxygenation. The advantage to this arrangement is that high pressure in the vessels pushes blood to the lungs and body. The mixing is mitigated by a ridge within the ventricle that diverts oxygen-rich blood through the systemic circulatory system and deoxygenated blood to the pulmocutaneous circuit. For this reason, amphibians are often described as having double circulation . Most reptiles also have a three-chambered heart similar to the amphibian heart that directs blood to the pulmonary and systemic circuits, as shown in Figure 40.4 c . The ventricle is divided more effectively by a partial septum, which results in less mixing of oxygenated and deoxygenated blood. Some reptiles (alligators and crocodiles) are the most primitive animals to exhibit a four-chambered heart. Crocodilians have a unique circulatory mechanism where the heart shunts blood from the lungs toward the stomach and other organs during long periods of submergence, for instance, while the animal waits for prey or stays underwater waiting for prey to rot. One adaptation includes two main arteries that leave the same part of the heart: one takes blood to the lungs and the other provides an alternate route to the stomach and other parts of the body. Two other adaptations include a hole in the heart between the two ventricles, called the foramen of Panizza, which allows blood to move from one side of the heart to the other, and specialized connective tissue that slows the blood flow to the lungs. Together these adaptations have made crocodiles and alligators one of the most evolutionarily successful animal groups on earth. In mammals and birds, the heart is also divided into four chambers: two atria and two ventricles, as illustrated in Figure 40.4 d . The oxygenated blood is separated from the deoxygenated blood, which improves the efficiency of double circulation and is probably required for the warm-blooded lifestyle of mammals and birds. The four-chambered heart of birds and mammals evolved independently from a three-chambered heart. The independent evolution of the same or a similar biological trait is referred to as convergent evolution. 40.2 Components of the Blood Learning Objectives By the end of this section, you will be able to: List the basic components of the blood Compare red and white blood cells Describe blood plasma and serum Hemoglobin is responsible for distributing oxygen, and to a lesser extent, carbon dioxide, throughout the circulatory systems of humans, vertebrates, and many invertebrates. The blood is more than the proteins, though. Blood is actually a term used to describe the liquid that moves through the vessels and includes plasma (the liquid portion, which contains water, proteins, salts, lipids, and glucose) and the cells (red and white cells) and cell fragments called platelets . Blood plasma is actually the dominant component of blood and contains the water, proteins, electrolytes, lipids, and glucose. The cells are responsible for carrying the gases (red cells) and immune the response (white). The platelets are responsible for blood clotting. Interstitial fluid that surrounds cells is separate from the blood, but in hemolymph, they are combined. In humans, cellular components make up approximately 45 percent of the blood and the liquid plasma 55 percent. Blood is 20 percent of a person’s extracellular fluid and eight percent of weight. The Role of Blood in the Body Blood, like the human blood illustrated in Figure 40.5 is important for regulation of the body’s systems and homeostasis. Blood helps maintain homeostasis by stabilizing pH, temperature, osmotic pressure, and by eliminating excess heat. Blood supports growth by distributing nutrients and hormones, and by removing waste. Blood plays a protective role by transporting clotting factors and platelets to prevent blood loss and transporting the disease-fighting agents or white blood cells to sites of infection. Red Blood Cells Red blood cells , or erythrocytes (erythro- = “red”; -cyte = “cell”), are specialized cells that circulate through the body delivering oxygen to cells; they are formed from stem cells in the bone marrow. In mammals, red blood cells are small biconcave cells that at maturity do not contain a nucleus or mitochondria and are only 7–8 µm in size. In birds and non-avian reptiles, a nucleus is still maintained in red blood cells. The red coloring of blood comes from the iron-containing protein hemoglobin, illustrated in Figure 40.6 a . The principal job of this protein is to carry oxygen, but it also transports carbon dioxide as well. Hemoglobin is packed into red blood cells at a rate of about 250 million molecules of hemoglobin per cell. Each hemoglobin molecule binds four oxygen molecules so that each red blood cell carries one billion molecules of oxygen. There are approximately 25 trillion red blood cells in the five liters of blood in the human body, which could carry up to 25 sextillion (25 × 10 21 ) molecules of oxygen in the body at any time. In mammals, the lack of organelles in erythrocytes leaves more room for the hemoglobin molecules, and the lack of mitochondria also prevents use of the oxygen for metabolic respiration. Only mammals have anucleated red blood cells, and some mammals (camels, for instance) even have nucleated red blood cells. The advantage of nucleated red blood cells is that these cells can undergo mitosis. Anucleated red blood cells metabolize anaerobically (without oxygen), making use of a primitive metabolic pathway to produce ATP and increase the efficiency of oxygen transport. Not all organisms use hemoglobin as the method of oxygen transport. Invertebrates that utilize hemolymph rather than blood use different pigments to bind to the oxygen. These pigments use copper or iron to the oxygen. Invertebrates have a variety of other respiratory pigments. Hemocyanin, a blue-green, copper-containing protein, illustrated in Figure 40.6 b is found in mollusks, crustaceans, and some of the arthropods. Chlorocruorin, a green-colored, iron-containing pigment is found in four families of polychaete tubeworms. Hemerythrin, a red, iron-containing protein is found in some polychaete worms and annelids and is illustrated in Figure 40.6 c . Despite the name, hemerythrin does not contain a heme group and its oxygen-carrying capacity is poor compared to hemoglobin. The small size and large surface area of red blood cells allows for rapid diffusion of oxygen and carbon dioxide across the plasma membrane. In the lungs, carbon dioxide is released and oxygen is taken in by the blood. In the tissues, oxygen is released from the blood and carbon dioxide is bound for transport back to the lungs. Studies have found that hemoglobin also binds nitrous oxide (NO). NO is a vasodilator that relaxes the blood vessels and capillaries and may help with gas exchange and the passage of red blood cells through narrow vessels. Nitroglycerin, a heart medication for angina and heart attacks, is converted to NO to help relax the blood vessels and increase oxygen flow through the body. A characteristic of red blood cells is their glycolipid and glycoprotein coating; these are lipids and proteins that have carbohydrate molecules attached. In humans, the surface glycoproteins and glycolipids on red blood cells vary between individuals, producing the different blood types, such as A, B, and O. Red blood cells have an average life span of 120 days, at which time they are broken down and recycled in the liver and spleen by phagocytic macrophages, a type of white blood cell. White Blood Cells White blood cells, also called leukocytes (leuko = white), make up approximately one percent by volume of the cells in blood. The role of white blood cells is very different than that of red blood cells: they are primarily involved in the immune response to identify and target pathogens, such as invading bacteria, viruses, and other foreign organisms. White blood cells are formed continually; some only live for hours or days, but some live for years. The morphology of white blood cells differs significantly from red blood cells. They have nuclei and do not contain hemoglobin. The different types of white blood cells are identified by their microscopic appearance after histologic staining, and each has a different specialized function. The two main groups, both illustrated in Figure 40.7 are the granulocytes, which include the neutrophils, eosinophils, and basophils, and the agranulocytes, which include the monocytes and lymphocytes. Granulocytes contain granules in their cytoplasm; the agranulocytes are so named because of the lack of granules in their cytoplasm. Some leukocytes become macrophages that either stay at the same site or move through the blood stream and gather at sites of infection or inflammation where they are attracted by chemical signals from foreign particles and damaged cells. Lymphocytes are the primary cells of the immune system and include B cells, T cells, and natural killer cells. B cells destroy bacteria and inactivate their toxins. They also produce antibodies. T cells attack viruses, fungi, some bacteria, transplanted cells, and cancer cells. T cells attack viruses by releasing toxins that kill the viruses. Natural killer cells attack a variety of infectious microbes and certain tumor cells. One reason that HIV poses significant management challenges is because the virus directly targets T cells by gaining entry through a receptor. Once inside the cell, HIV then multiplies using the T cell’s own genetic machinery. After the HIV virus replicates, it is transmitted directly from the infected T cell to macrophages. The presence of HIV can remain unrecognized for an extensive period of time before full disease symptoms develop. Platelets and Coagulation Factors Blood must clot to heal wounds and prevent excess blood loss. Small cell fragments called platelets (thrombocytes) are attracted to the wound site where they adhere by extending many projections and releasing their contents. These contents activate other platelets and also interact with other coagulation factors, which convert fibrinogen, a water-soluble protein present in blood serum into fibrin (a non-water soluble protein), causing the blood to clot. Many of the clotting factors require vitamin K to work, and vitamin K deficiency can lead to problems with blood clotting. Many platelets converge and stick together at the wound site forming a platelet plug (also called a fibrin clot), as illustrated in Figure 40.8 b . The plug or clot lasts for a number of days and stops the loss of blood. Platelets are formed from the disintegration of larger cells called megakaryocytes, like that shown in Figure 40.8 a . For each megakaryocyte, 2000–3000 platelets are formed with 150,000 to 400,000 platelets present in each cubic millimeter of blood. Each platelet is disc shaped and 2–4 μm in diameter. They contain many small vesicles but do not contain a nucleus. Plasma and Serum The liquid component of blood is called plasma, and it is separated by spinning or centrifuging the blood at high rotations (3000 rpm or higher). The blood cells and platelets are separated by centrifugal forces to the bottom of a specimen tube. The upper liquid layer, the plasma, consists of 90 percent water along with various substances required for maintaining the body’s pH, osmotic load, and for protecting the body. The plasma also contains the coagulation factors and antibodies. The plasma component of blood without the coagulation factors is called the serum . Serum is similar to interstitial fluid in which the correct composition of key ions acting as electrolytes is essential for normal functioning of muscles and nerves. Other components in the serum include proteins that assist with maintaining pH and osmotic balance while giving viscosity to the blood. The serum also contains antibodies, specialized proteins that are important for defense against viruses and bacteria. Lipids, including cholesterol, are also transported in the serum, along with various other substances including nutrients, hormones, metabolic waste, plus external substances, such as, drugs, viruses, and bacteria. Human serum albumin is the most abundant protein in human blood plasma and is synthesized in the liver. Albumin, which constitutes about half of the blood serum protein, transports hormones and fatty acids, buffers pH, and maintains osmotic pressures. Immunoglobin is a protein antibody produced in the mucosal lining and plays an important role in antibody mediated immunity. Evolution Connection Blood Types Related to Proteins on the Surface of the Red Blood Cells Red blood cells are coated in antigens made of glycolipids and glycoproteins. The composition of these molecules is determined by genetics, which have evolved over time. In humans, the different surface antigens are grouped into 24 different blood groups with more than 100 different antigens on each red blood cell. The two most well known blood groups are the ABO, shown in Figure 40.9 , and Rh systems. The surface antigens in the ABO blood group are glycolipids, called antigen A and antigen B. People with blood type A have antigen A, those with blood type B have antigen B, those with blood type AB have both antigens, and people with blood type O have neither antigen. Antibodies called agglutinougens are found in the blood plasma and react with the A or B antigens, if the two are mixed. When type A and type B blood are combined, agglutination (clumping) of the blood occurs because of antibodies in the plasma that bind with the opposing antigen; this causes clots that coagulate in the kidney causing kidney failure. Type O blood has neither A or B antigens, and therefore, type O blood can be given to all blood types. Type O negative blood is the universal donor. Type AB positive blood is the universal acceptor because it has both A and B antigen. The ABO blood groups were discovered in 1900 and 1901 by Karl Landsteiner at the University of Vienna. The Rh blood group was first discovered in Rhesus monkeys. Most people have the Rh antigen (Rh+) and do not have anti-Rh antibodies in their blood. The few people who do not have the Rh antigen and are Rh– can develop anti-Rh antibodies if exposed to Rh+ blood. This can happen after a blood transfusion or after an Rh– woman has an Rh+ baby. The first exposure does not usually cause a reaction; however, at the second exposure, enough antibodies have built up in the blood to produce a reaction that causes agglutination and breakdown of red blood cells. An injection can prevent this reaction. Link to Learning Play a blood typing game on the Nobel Prize website to solidify your understanding of blood types. 40.3 Mammalian Heart and Blood Vessels Learning Objectives By the end of this section, you will be able to: Describe the structure of the heart and explain how cardiac muscle is different from other muscles Describe the cardiac cycle Explain the structure of arteries, veins, and capillaries, and how blood flows through the body The heart is a complex muscle that pumps blood through the three divisions of the circulatory system: the coronary (vessels that serve the heart), pulmonary (heart and lungs), and systemic (systems of the body), as shown in Figure 40.10 . Coronary circulation intrinsic to the heart takes blood directly from the main artery (aorta) coming from the heart. For pulmonary and systemic circulation, the heart has to pump blood to the lungs or the rest of the body, respectively. In vertebrates, the lungs are relatively close to the heart in the thoracic cavity. The shorter distance to pump means that the muscle wall on the right side of the heart is not as thick as the left side which must have enough pressure to pump blood all the way to your big toe. Visual Connection Which of the following statements about the circulatory system is false? Blood in the pulmonary vein is deoxygenated. Blood in the inferior vena cava is deoxygenated. Blood in the pulmonary artery is deoxygenated. Blood in the aorta is oxygenated. Structure of the Heart The heart muscle is asymmetrical as a result of the distance blood must travel in the pulmonary and systemic circuits. Since the right side of the heart sends blood to the pulmonary circuit it is smaller than the left side which must send blood out to the whole body in the systemic circuit, as shown in Figure 40.11 . In humans, the heart is about the size of a clenched fist; it is divided into four chambers: two atria and two ventricles. There is one atrium and one ventricle on the right side and one atrium and one ventricle on the left side. The atria are the chambers that receive blood, and the ventricles are the chambers that pump blood. The right atrium receives deoxygenated blood from the superior vena cava , which drains blood from the jugular vein that comes from the brain and from the veins that come from the arms, as well as from the inferior vena cava which drains blood from the veins that come from the lower organs and the legs. In addition, the right atrium receives blood from the coronary sinus which drains deoxygenated blood from the heart itself. This deoxygenated blood then passes to the right ventricle through the atrioventricular valve or the tricuspid valve , a flap of connective tissue that opens in only one direction to prevent the backflow of blood. The valve separating the chambers on the left side of the heart valve is called the biscuspid or mitral valve. After it is filled, the right ventricle pumps the blood through the pulmonary arteries, by-passing the semilunar valve (or pulmonic valve) to the lungs for re-oxygenation. After blood passes through the pulmonary arteries, the right semilunar valves close preventing the blood from flowing backwards into the right ventricle. The left atrium then receives the oxygen-rich blood from the lungs via the pulmonary veins. This blood passes through the bicuspid valve or mitral valve (the atrioventricular valve on the left side of the heart) to the left ventricle where the blood is pumped out through aorta , the major artery of the body, taking oxygenated blood to the organs and muscles of the body. Once blood is pumped out of the left ventricle and into the aorta, the aortic semilunar valve (or aortic valve) closes preventing blood from flowing backward into the left ventricle. This pattern of pumping is referred to as double circulation and is found in all mammals. Visual Connection Which of the following statements about the heart is false? The mitral valve separates the left ventricle from the left atrium. Blood travels through the bicuspid valve to the left atrium. Both the aortic and the pulmonary valves are semilunar valves. The mitral valve is an atrioventricular valve. The heart is composed of three layers; the epicardium, the myocardium, and the endocardium, illustrated in Figure 40.11 . The inner wall of the heart has a lining called the endocardium . The myocardium consists of the heart muscle cells that make up the middle layer and the bulk of the heart wall. The outer layer of cells is called the epicardium , of which the second layer is a membranous layered structure called the pericardium that surrounds and protects the heart; it allows enough room for vigorous pumping but also keeps the heart in place to reduce friction between the heart and other structures. The heart has its own blood vessels that supply the heart muscle with blood. The coronary arteries branch from the aorta and surround the outer surface of the heart like a crown. They diverge into capillaries where the heart muscle is supplied with oxygen before converging again into the coronary veins to take the deoxygenated blood back to the right atrium where the blood will be re-oxygenated through the pulmonary circuit. The heart muscle will die without a steady supply of blood. Atherosclerosis is the blockage of an artery by the buildup of fatty plaques. Because of the size (narrow) of the coronary arteries and their function in serving the heart itself, atherosclerosis can be deadly in these arteries. The slowdown of blood flow and subsequent oxygen deprivation that results from atherosclerosis causes severe pain, known as angina , and complete blockage of the arteries will cause myocardial infarction : the death of cardiac muscle tissue, commonly known as a heart attack. The Cardiac Cycle The main purpose of the heart is to pump blood through the body; it does so in a repeating sequence called the cardiac cycle. The cardiac cycle is the coordination of the filling and emptying of the heart of blood by electrical signals that cause the heart muscles to contract and relax. The human heart beats over 100,000 times per day. In each cardiac cycle, the heart contracts ( systole ), pushing out the blood and pumping it through the body; this is followed by a relaxation phase ( diastole ), where the heart fills with blood, as illustrated in Figure 40.12 . The atria contract at the same time, forcing blood through the atrioventricular valves into the ventricles. Closing of the atrioventricular valves produces a monosyllabic “lup” sound. Following a brief delay, the ventricles contract at the same time forcing blood through the semilunar valves into the aorta and the artery transporting blood to the lungs (via the pulmonary artery). Closing of the semilunar valves produces a monosyllabic “dup” sound. The pumping of the heart is a function of the cardiac muscle cells, or cardiomyocytes, that make up the heart muscle. Cardiomyocytes , shown in Figure 40.13 , are distinctive muscle cells that are striated like skeletal muscle but pump rhythmically and involuntarily like smooth muscle; they are connected by intercalated disks exclusive to cardiac muscle. They are self-stimulated for a period of time and isolated cardiomyocytes will beat if given the correct balance of nutrients and electrolytes. The autonomous beating of cardiac muscle cells is regulated by the heart’s internal pacemaker that uses electrical signals to time the beating of the heart. The electrical signals and mechanical actions, illustrated in Figure 40.14 , are intimately intertwined. The internal pacemaker starts at the sinoatrial (SA) node , which is located near the wall of the right atrium. Electrical charges spontaneously pulse from the SA node causing the two atria to contract in unison. The pulse reaches a second node, called the atrioventricular (AV) node, between the right atrium and right ventricle where it pauses for approximately 0.1 second before spreading to the walls of the ventricles. From the AV node, the electrical impulse enters the bundle of His, then to the left and right bundle branches extending through the interventricular septum. Finally, the Purkinje fibers conduct the impulse from the apex of the heart up the ventricular myocardium, and then the ventricles contract. This pause allows the atria to empty completely into the ventricles before the ventricles pump out the blood. The electrical impulses in the heart produce electrical currents that flow through the body and can be measured on the skin using electrodes. This information can be observed as an electrocardiogram (ECG) —a recording of the electrical impulses of the cardiac muscle. Link to Learning Visit this site and select the dropdown “Your Heart’s Electrical System” to see the heart’s “pacemaker” in action. Arteries, Veins, and Capillaries The blood from the heart is carried through the body by a complex network of blood vessels ( Figure 40.15 ). Arteries take blood away from the heart. The main artery is the aorta that branches into major arteries that take blood to different limbs and organs. These major arteries include the carotid artery that takes blood to the brain, the brachial arteries that take blood to the arms, and the thoracic artery that takes blood to the thorax and then into the hepatic, renal, and gastric arteries for the liver, kidney, and stomach, respectively. The iliac artery takes blood to the lower limbs. The major arteries diverge into minor arteries, and then smaller vessels called arterioles , to reach more deeply into the muscles and organs of the body. Arterioles diverge into capillary beds. Capillary beds contain a large number (10 to 100) of capillaries that branch among the cells and tissues of the body. Capillaries are narrow-diameter tubes that can fit red blood cells through in single file and are the sites for the exchange of nutrients, waste, and oxygen with tissues at the cellular level. Fluid also crosses into the interstitial space from the capillaries. The capillaries converge again into venules that connect to minor veins that finally connect to major veins that take blood high in carbon dioxide back to the heart. Veins are blood vessels that bring blood back to the heart. The major veins drain blood from the same organs and limbs that the major arteries supply. Fluid is also brought back to the heart via the lymphatic system. The structure of the different types of blood vessels reflects their function or layers. There are three distinct layers, or tunics, that form the walls of blood vessels ( Figure 40.16 ). The first tunic is a smooth, inner lining of endothelial cells that are in contact with the red blood cells. The endothelial tunic is continuous with the endocardium of the heart. In capillaries, this single layer of cells is the location of diffusion of oxygen and carbon dioxide between the endothelial cells and red blood cells, as well as the exchange site via endocytosis and exocytosis. The movement of materials at the site of capillaries is regulated by vasoconstriction , narrowing of the blood vessels, and vasodilation , widening of the blood vessels; this is important in the overall regulation of blood pressure. Veins and arteries both have two further tunics that surround the endothelium: the middle tunic is composed of smooth muscle and the outermost layer is connective tissue (collagen and elastic fibers). The elastic connective tissue stretches and supports the blood vessels, and the smooth muscle layer helps regulate blood flow by altering vascular resistance through vasoconstriction and vasodilation. The arteries have thicker smooth muscle and connective tissue than the veins to accommodate the higher pressure and speed of freshly pumped blood. The veins are thinner walled as the pressure and rate of flow are much lower. In addition, veins are structurally different than arteries in that veins have valves to prevent the backflow of blood. Because veins have to work against gravity to get blood back to the heart, contraction of skeletal muscle assists with the flow of blood back to the heart. 40.4 Blood Flow and Blood Pressure Regulation Learning Objectives By the end of this section, you will be able to: Describe the system of blood flow through the body Describe how blood pressure is regulated Blood pressure (BP) is the pressure exerted by blood on the walls of a blood vessel that helps to push blood through the body. Systolic blood pressure measures the amount of pressure that blood exerts on vessels while the heart is beating. The optimal systolic blood pressure is 120 mmHg. Diastolic blood pressure measures the pressure in the vessels between heartbeats. The optimal diastolic blood pressure is 80 mmHg. Many factors can affect blood pressure, such as hormones, stress, exercise, eating, sitting, and standing. Blood flow through the body is regulated by the size of blood vessels, by the action of smooth muscle, by one-way valves, and by the fluid pressure of the blood itself. How Blood Flows Through the Body Blood is pushed through the body by the action of the pumping heart. With each rhythmic pump, blood is pushed under high pressure and velocity away from the heart, initially along the main artery, the aorta. In the aorta, the blood travels at 30 cm/sec. As blood moves into the arteries, arterioles, and ultimately to the capillary beds, the rate of movement slows dramatically to about 0.026 cm/sec, one-thousand times slower than the rate of movement in the aorta. While the diameter of each individual arteriole and capillary is far narrower than the diameter of the aorta, and according to the law of continuity, fluid should travel faster through a narrower diameter tube, the rate is actually slower due to the overall diameter of all the combined capillaries being far greater than the diameter of the individual aorta. The slow rate of travel through the capillary beds, which reach almost every cell in the body, assists with gas and nutrient exchange and also promotes the diffusion of fluid into the interstitial space. After the blood has passed through the capillary beds to the venules, veins, and finally to the main venae cavae, the rate of flow increases again but is still much slower than the initial rate in the aorta. Blood primarily moves in the veins by the rhythmic movement of smooth muscle in the vessel wall and by the action of the skeletal muscle as the body moves. Because most veins must move blood against the pull of gravity, blood is prevented from flowing backward in the veins by one-way valves. Because skeletal muscle contraction aids in venous blood flow, it is important to get up and move frequently after long periods of sitting so that blood will not pool in the extremities. Blood flow through the capillary beds is regulated depending on the body’s needs and is directed by nerve and hormone signals. For example, after a large meal, most of the blood is diverted to the stomach by vasodilation of vessels of the digestive system and vasoconstriction of other vessels. During exercise, blood is diverted to the skeletal muscles through vasodilation while blood to the digestive system would be lessened through vasoconstriction. The blood entering some capillary beds is controlled by small muscles, called precapillary sphincters, illustrated in Figure 40.17 . If the sphincters are open, the blood will flow into the associated branches of the capillary blood. If all of the sphincters are closed, then the blood will flow directly from the arteriole to the venule through the thoroughfare channel (see Figure 40.17 ). These muscles allow the body to precisely control when capillary beds receive blood flow. At any given moment only about 5-10% of our capillary beds actually have blood flowing through them. Visual Connection Varicose veins are veins that become enlarged because the valves no longer close properly, allowing blood to flow backward. Varicose veins are often most prominent on the legs. Why do you think this is the case? Link to Learning See the circulatory system’s blood flow. Click to view content Proteins and other large solutes cannot leave the capillaries. The loss of the watery plasma creates a hyperosmotic solution within the capillaries, especially near the venules. This causes about 85% of the plasma that leaves the capillaries to eventually diffuses back into the capillaries near the venules. The remaining 15% of blood plasma drains out from the interstitial fluid into nearby lymphatic vessels ( Figure 40.18 ). The fluid in the lymph is similar in composition to the interstitial fluid. The lymph fluid passes through lymph nodes before it returns to the heart via the vena cava. Lymph nodes are specialized organs that filter the lymph by percolation through a maze of connective tissue filled with white blood cells. The white blood cells remove infectious agents, such as bacteria and viruses, to clean the lymph before it returns to the bloodstream. After it is cleaned, the lymph returns to the heart by the action of smooth muscle pumping, skeletal muscle action, and one-way valves joining the returning blood near the junction of the venae cavae entering the right atrium of the heart. Evolution Connection Vertebrate Diversity in Blood Circulation Blood circulation has evolved differently in vertebrates and may show variation in different animals for the required amount of pressure, organ and vessel location, and organ size. Animals with longs necks and those that live in cold environments have distinct blood pressure adaptations. Long necked animals, such as giraffes, need to pump blood upward from the heart against gravity. The blood pressure required from the pumping of the left ventricle would be equivalent to 250 mm Hg (mm Hg = millimeters of mercury, a unit of pressure) to reach the height of a giraffe’s head, which is 2.5 meters higher than the heart. However, if checks and balances were not in place, this blood pressure would damage the giraffe’s brain, particularly if it was bending down to drink. These checks and balances include valves and feedback mechanisms that reduce the rate of cardiac output. Long-necked dinosaurs such as the sauropods had to pump blood even higher, up to ten meters above the heart. This would have required a blood pressure of more than 600 mm Hg, which could only have been achieved by an enormous heart. Evidence for such an enormous heart does not exist and mechanisms to reduce the blood pressure required include the slowing of metabolism as these animals grew larger. It is likely that they did not routinely feed on tree tops but grazed on the ground. Living in cold water, whales need to maintain the temperature in their blood. This is achieved by the veins and arteries being close together so that heat exchange can occur. This mechanism is called a countercurrent heat exchanger. The blood vessels and the whole body are also protected by thick layers of blubber to prevent heat loss. In land animals that live in cold environments, thick fur and hibernation are used to retain heat and slow metabolism. Blood Pressure The pressure of the blood flow in the body is produced by the hydrostatic pressure of the fluid (blood) against the walls of the blood vessels. Fluid will move from areas of high to low hydrostatic pressures. In the arteries, the hydrostatic pressure near the heart is very high and blood flows to the arterioles where the rate of flow is slowed by the narrow openings of the arterioles. During systole, when new blood is entering the arteries, the artery walls stretch to accommodate the increase of pressure of the extra blood; during diastole, the walls return to normal because of their elastic properties. The blood pressure of the systole phase and the diastole phase, graphed in Figure 40.19 , gives the two pressure readings for blood pressure. For example, 120/80 indicates a reading of 120 mm Hg during the systole and 80 mm Hg during diastole. Throughout the cardiac cycle, the blood continues to empty into the arterioles at a relatively even rate. This resistance to blood flow is called peripheral resistance . Blood Pressure Regulation Cardiac output is the volume of blood pumped by the heart in one minute. It is calculated by multiplying the number of heart contractions that occur per minute (heart rate) times the stroke volume (the volume of blood pumped into the aorta per contraction of the left ventricle). Therefore, cardiac output can be increased by increasing heart rate, as when exercising. However, cardiac output can also be increased by increasing stroke volume, such as if the heart contracts with greater strength. Stroke volume can also be increased by speeding blood circulation through the body so that more blood enters the heart between contractions. During heavy exertion, the blood vessels relax and increase in diameter, offsetting the increased heart rate and ensuring adequate oxygenated blood gets to the muscles. Stress triggers a decrease in the diameter of the blood vessels, consequently increasing blood pressure. These changes can also be caused by nerve signals or hormones, and even standing up or lying down can have a great effect on blood pressure.
microbiology
Summary 18.1 Overview of Specific Adaptive Immunity Adaptive immunity is an acquired defense against foreign pathogens that is characterized by specificity and memory. The first exposure to an antigen stimulates a primary response , and subsequent exposures stimulate a faster and strong secondary response. Adaptive immunity is a dual system involving humoral immunity (antibodies produced by B cells) and cellular immunity (T cells directed against intracellular pathogens). Antigens , also called immunogens , are molecules that activate adaptive immunity. A single antigen possesses smaller epitopes , each capable of inducing a specific adaptive immune response. An antigen’s ability to stimulate an immune response depends on several factors, including its molecular class, molecular complexity, and size. Antibodies ( immunoglobulins ) are Y-shaped glycoproteins with two Fab sites for binding antigens and an Fc portion involved in complement activation and opsonization. The five classes of antibody are IgM , IgG , IgA , IgE , and IgD , each differing in size, arrangement, location within the body, and function. The five primary functions of antibodies are neutralization, opsonization, agglutination, complement activation, and antibody-dependent cell-mediated cytotoxicity (ADCC). 18.2 Major Histocompatibility Complexes and Antigen-Presenting Cells Major histocompatibility complex (MHC) is a collection of genes coding for glycoprotein molecules expressed on the surface of all nucleated cells. MHC I molecules are expressed on all nucleated cells and are essential for presentation of normal “self” antigens. Cells that become infected by intracellular pathogens can present foreign antigens on MHC I as well, marking the infected cell for destruction. MHC II molecules are expressed only on the surface of antigen-presenting cells (macrophages, dendritic cells, and B cells). Antigen presentation with MHC II is essential for the activation of T cells. Antigen-presenting cells (APCs) primarily ingest pathogens by phagocytosis, destroy them in the phagolysosomes, process the protein antigens, and select the most antigenic/immunodominant epitopes with MHC II for presentation to T cells. Cross-presentation is a mechanism of antigen presentation and T-cell activation used by dendritic cells not directly infected by the pathogen; it involves phagocytosis of the pathogen but presentation on MHC I rather than MHC II. 18.3 T Lymphocytes and Cellular Immunity Immature T lymphocytes are produced in the red bone marrow and travel to the thymus for maturation. Thymic selection is a three-step process of negative and positive selection that determines which T cells will mature and exit the thymus into the peripheral bloodstream. Central tolerance involves negative selection of self-reactive T cells in the thymus, and peripheral tolerance involves anergy and regulatory T cells that prevent self-reactive immune responses and autoimmunity. The TCR is similar in structure to immunoglobulins, but less complex. Millions of unique epitope-binding TCRs are encoded through a process of genetic rearrangement of V, D, and J gene segments. T cells can be divided into three classes— helper T cells, cytotoxic T cells, and regulatory T cells— based on their expression of CD4 or CD8, the MHC molecules with which they interact for activation, and their respective functions. Activated helper T cells differentiate into T H 1, T H 2, T H 17 , or memory T cell subtypes . Differentiation is directed by the specific cytokines to which they are exposed. T H 1, T H 2, and T H 17 perform different functions related to stimulation of adaptive and innate immune defenses. Memory T cells are long-lived cells that can respond quickly to secondary exposures. Once activated, cytotoxic T cells target and kill cells infected with intracellular pathogens. Killing requires recognition of specific pathogen epitopes presented on the cell surface using MHC I molecules. Killing is mediated by perforin and granzymes that induce apoptosis. Superantigens are bacterial or viral proteins that cause a nonspecific activation of helper T cells, leading to an excessive release of cytokines ( cytokine storm ) and a systemic, potentially fatal inflammatory response. 18.4 B Lymphocytes and Humoral Immunity B lymphocytes or B cells produce antibodies involved in humoral immunity. B cells are produced in the bone marrow, where the initial stages of maturation occur, and travel to the spleen for final steps of maturation into naïve mature B cells. B-cell receptors (BCRs) are membrane-bound monomeric forms of IgD and IgM that bind specific antigen epitopes with their Fab antigen-binding regions. Diversity of antigen binding specificity is created by genetic rearrangement of V, D, and J segments similar to the mechanism used for TCR diversity. Protein antigens are called T-dependent antigens because they can only activate B cells with the cooperation of helper T cells. Other molecule classes do not require T cell cooperation and are called T-independent antigens . T cell-independent activation of B cells involves cross-linkage of BCRs by repetitive nonprotein antigen epitopes. It is characterized by the production of IgM by plasma cells and does not produce memory B cells. T cell-dependent activation of B cells involves processing and presentation of protein antigens to helper T cells, activation of the B cells by cytokines secreted from activated T H 2 cells, and plasma cells that produce different classes of antibodies as a result of class switching . Memory B cells are also produced. Secondary exposures to T-dependent antigens result in a secondary antibody response initiated by memory B cells. The secondary response develops more quickly and produces higher and more sustained levels of antibody with higher affinity for the specific antigen. 18.5 Vaccines Adaptive immunity can be divided into four distinct classifications: natural active immunity, natural passive immunity, artificial passive immunity, and artificial active immunity. Artificial active immunity is the foundation for vaccination and vaccine development. Vaccination programs not only confer artificial immunity on individuals, but also foster herd immunity in populations. Variolation against smallpox originated in the 10 th century in China, but the procedure was risky because it could cause the disease it was intended to prevent. Modern vaccination was developed by Edward Jenner, who developed the practice of inoculating patients with infectious materials from cowpox lesions to prevent smallpox. Live attenuated vaccines and inactivated vaccines contain whole pathogens that are weak, killed, or inactivated. Subunit vaccines, toxoid vaccines, and conjugate vaccines contain acellular components with antigens that stimulate an immune response.
Chapter Outline 18.1 Overview of Specific Adaptive Immunity 18.2 Major Histocompatibility Complexes and Antigen-Presenting Cells 18.3 T Lymphocytes and Cellular Immunity 18.4 B Lymphocytes and Humoral Immunity 18.5 Vaccines Introduction People living in developed nations and born in the 1960s or later may have difficulty understanding the once heavy burden of devastating infectious diseases. For example, smallpox , a deadly viral disease, once destroyed entire civilizations but has since been eradicated. Thanks to the vaccination efforts by multiple groups, including the World Health Organization, Rotary International, and the United Nations Children’s Fund (UNICEF), smallpox has not been diagnosed in a patient since 1977. Polio is another excellent example. This crippling viral disease paralyzed patients, who were often kept alive in “iron lung wards” as recently as the 1950s ( Figure 18.1 ). Today, vaccination against polio has nearly eradicated the disease. Vaccines have also reduced the prevalence of once-common infectious diseases such as chickenpox , German measles , measles , mumps , and whooping cough . The success of these and other vaccines is due to the very specific and adaptive host defenses that are the focus of this chapter. Innate Nonspecific Host Defenses described innate immunity against microbial pathogens. Higher animals, such as humans, also possess an adaptive immune defense, which is highly specific for individual microbial pathogens. This specific adaptive immunity is acquired through active infection or vaccination and serves as an important defense against pathogens that evade the defenses of innate immunity.
[ { "answer": { "ans_choice": 0, "ans_text": "A" }, "bloom": null, "hl_context": "Once a B cell is activated , it undergoes clonal proliferation and daughter cells differentiate into plasma cells . <hl> Plasma cells are antibody factories that secrete large quantities of antibodies . <hl> After differentiation , the surface BCRs disappear and the plasma cell secretes pentameric IgM molecules that have the same antigen specificity as the BCRs ( Figure 18.21 ) .", "hl_sentences": "Plasma cells are antibody factories that secrete large quantities of antibodies .", "question": { "cloze_format": "Antibodies are produced by ________.", "normal_format": "What produced Antibodies? ", "question_choices": [ "plasma cells", "T cells", "bone marrow", "Macrophages" ], "question_id": "fs-id1167660323124", "question_text": "Antibodies are produced by ________." }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 1, "ans_text": "B" }, "bloom": null, "hl_context": "As explained in Overview of Specific Adaptive Immunity , the antibodies involved in humoral immunity often bind pathogens and toxins before they can attach to and invade host cells . Thus , humoral immunity is primarily concerned with fighting pathogens in extracellular spaces . However , pathogens that have already gained entry to host cells are largely protected from the humoral antibody-mediated defenses . <hl> Cellular immunity , on the other hand , targets and eliminates intracellular pathogens through the actions of T lymphocytes , or T cells ( Figure 18.13 ) . <hl> T cells also play a more central role in orchestrating the overall adaptive immune response ( humoral as well as cellular ) along with the cellular defenses of innate immunity .", "hl_sentences": "Cellular immunity , on the other hand , targets and eliminates intracellular pathogens through the actions of T lymphocytes , or T cells ( Figure 18.13 ) .", "question": { "cloze_format": "Cellular adaptive immunity is carried out by ________.", "normal_format": "What is cellular adaptive immunity carried out by?", "question_choices": [ "B cells", "T cells", "bone marrow", "neutrophils" ], "question_id": "fs-id1167662771044", "question_text": "Cellular adaptive immunity is carried out by ________." }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 3, "ans_text": "D" }, "bloom": null, "hl_context": "One reason the three-dimensional complexity of antigens is so important is that antibodies and T cells do not recognize and interact with an entire antigen but with smaller exposed regions on the surface of antigens called epitopes . <hl> A single antigen may possess several different epitopes ( Figure 18.3 ) , and different antibodies may bind to different epitopes on the same antigen ( Figure 18.4 ) . <hl> For example , the bacterial flagellum is a large , complex protein structure that can possess hundreds or even thousands of epitopes with unique three-dimensional structures . Moreover , flagella from different bacterial species ( or even strains of the same species ) contain unique epitopes that can only be bound by specific antibodies .", "hl_sentences": "A single antigen may possess several different epitopes ( Figure 18.3 ) , and different antibodies may bind to different epitopes on the same antigen ( Figure 18.4 ) .", "question": { "cloze_format": "A single antigen molecule may be composed of many individual ________.", "normal_format": "An single antigen molecule may be dcomposed into what?", "question_choices": [ "T-cell receptors", "B-cell receptors", "MHC II", "epitopes" ], "question_id": "fs-id1167662665461", "question_text": "A single antigen molecule may be composed of many individual ________." }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 2, "ans_text": "C" }, "bloom": null, "hl_context": "Antigens may belong to any number of molecular classes , including carbohydrates , lipids , nucleic acids , proteins , and combinations of these molecules . Antigens of different classes vary in their ability to stimulate adaptive immune defenses as well as in the type of response they stimulate ( humoral or cellular ) . <hl> The structural complexity of an antigenic molecule is an important factor in its antigenic potential . <hl> <hl> In general , more complex molecules are more effective as antigens . <hl> <hl> For example , the three-dimensional complex structure of proteins make them the most effective and potent antigens , capable of stimulating both humoral and cellular immunity . <hl> In comparison , carbohydrates are less complex in structure and therefore less effective as antigens ; they can only stimulate humoral immune defenses . Lipids and nucleic acids are the least antigenic molecules , and in some cases may only become antigenic when combined with proteins or carbohydrates to form glycolipids , lipoproteins , or nucleoproteins .", "hl_sentences": "The structural complexity of an antigenic molecule is an important factor in its antigenic potential . In general , more complex molecules are more effective as antigens . For example , the three-dimensional complex structure of proteins make them the most effective and potent antigens , capable of stimulating both humoral and cellular immunity .", "question": { "cloze_format": "The class of molecules that is the most antigenic are ___.", "normal_format": "Which class of molecules is the most antigenic?", "question_choices": [ "polysaccharides", "lipids", "proteins", "carbohydrates" ], "question_id": "fs-id1167660276851", "question_text": "Which class of molecules is the most antigenic?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 0, "ans_text": "A" }, "bloom": null, "hl_context": "<hl> MHC I molecules , found on all normal , healthy , nucleated cells , signal to the immune system that the cell is a normal “ self ” cell . <hl> In a healthy cell , proteins normally found in the cytoplasm are degraded by proteasomes ( enzyme complexes responsible for degradation and processing of proteins ) and processed into self-antigen epitopes ; these self-antigen epitopes bind within the MHC I antigen-binding cleft and are then presented on the cell surface . Immune cells , such as NK cells , recognize these self-antigens and do not target the cell for destruction . <hl> However , if a cell becomes infected with an intracellular pathogen ( e . g . , a virus ) , protein antigens specific to the pathogen are processed in the proteasomes and bind with MHC I molecules for presentation on the cell surface . <hl> <hl> This presentation of pathogen-specific antigens with MHC I signals that the infected cell must be targeted for destruction along with the pathogen . <hl>", "hl_sentences": "MHC I molecules , found on all normal , healthy , nucleated cells , signal to the immune system that the cell is a normal “ self ” cell . However , if a cell becomes infected with an intracellular pathogen ( e . g . , a virus ) , protein antigens specific to the pathogen are processed in the proteasomes and bind with MHC I molecules for presentation on the cell surface . This presentation of pathogen-specific antigens with MHC I signals that the infected cell must be targeted for destruction along with the pathogen .", "question": { "cloze_format": "MHC I molecules present ___.", "normal_format": "What do MHC I molecules present?", "question_choices": [ "processed foreign antigens from proteasomes.", "processed self-antigens from phagolysosome.", "antibodies.", "T cell antigens." ], "question_id": "fs-id1167662450417", "question_text": "MHC I molecules present" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 1, "ans_text": "B" }, "bloom": null, "hl_context": "After a dendritic cell recognizes and attaches to a pathogen cell , the pathogen is internalized by phagocytosis and is initially contained within a phagosome . <hl> Lysosomes containing antimicrobial enzymes and chemicals fuse with the phagosome to create a phagolysosome , where degradation of the pathogen for antigen processing begins . <hl> <hl> Proteases ( protein-degrading ) are especially important in antigen processing because only protein antigen epitopes are presented to T cells by MHC II ( Figure 18.12 ) . <hl>", "hl_sentences": "Lysosomes containing antimicrobial enzymes and chemicals fuse with the phagosome to create a phagolysosome , where degradation of the pathogen for antigen processing begins . Proteases ( protein-degrading ) are especially important in antigen processing because only protein antigen epitopes are presented to T cells by MHC II ( Figure 18.12 ) .", "question": { "cloze_format": "MHC II molecules present ___.", "normal_format": "What do MHC II molecules present?", "question_choices": [ "processed self-antigens from proteasomes.", "processed foreign antigens from phagolysosomes.", "antibodies.", "T cell receptors." ], "question_id": "fs-id1167660364789", "question_text": "MHC II molecules present" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 1, "ans_text": "B" }, "bloom": null, "hl_context": "There are two classes of MHC molecules involved in adaptive immunity , MHC I and MHC II ( Figure 18.11 ) . <hl> MHC I molecules are found on all nucleated cells ; they present normal self-antigens as well as abnormal or nonself pathogens to the effector T cells involved in cellular immunity . <hl> In contrast , MHC II molecules are only found on macrophages , dendritic cells , and B cells ; they present abnormal or nonself pathogen antigens for the initial activation of T cells .", "hl_sentences": "MHC I molecules are found on all nucleated cells ; they present normal self-antigens as well as abnormal or nonself pathogens to the effector T cells involved in cellular immunity .", "question": { "cloze_format": "___ is/are a type of antigen-presenting molecule that is found on all nucleated cells.", "normal_format": "Which type of antigen-presenting molecule is found on all nucleated cells?", "question_choices": [ "MHC II", "MHC I", "antibodies", "B-cell receptors" ], "question_id": "fs-id1167660619092", "question_text": "Which type of antigen-presenting molecule is found on all nucleated cells?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 1, "ans_text": "B" }, "bloom": null, "hl_context": "There are two classes of MHC molecules involved in adaptive immunity , MHC I and MHC II ( Figure 18.11 ) . MHC I molecules are found on all nucleated cells ; they present normal self-antigens as well as abnormal or nonself pathogens to the effector T cells involved in cellular immunity . <hl> In contrast , MHC II molecules are only found on macrophages , dendritic cells , and B cells ; they present abnormal or nonself pathogen antigens for the initial activation of T cells . <hl>", "hl_sentences": "In contrast , MHC II molecules are only found on macrophages , dendritic cells , and B cells ; they present abnormal or nonself pathogen antigens for the initial activation of T cells .", "question": { "cloze_format": "The antigen-presenting molecule ___ is found only on macrophages, dendritic cells, and B cells.", "normal_format": "Which type of antigen-presenting molecule is found only on macrophages, dendritic cells, and B cells?", "question_choices": [ "MHC I", "MHC II", "T-cell receptors", "B-cell receptors" ], "question_id": "fs-id1167662747086", "question_text": "Which type of antigen-presenting molecule is found only on macrophages, dendritic cells, and B cells?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 3, "ans_text": "D" }, "bloom": null, "hl_context": "<hl> The mechanism of T cell activation by superantigens involves their simultaneous binding to MHC II molecules of APCs and the variable region of the TCR β chain . <hl> This binding occurs outside of the antigen-binding cleft of MHC II , so the superantigen will bridge together and activate MHC II and TCR without specific foreign epitope recognition ( Figure 18.19 ) . <hl> The result is an excessive , uncontrolled release of cytokines , often called a cytokine storm , which stimulates an excessive inflammatory response . <hl> This can lead to a dangerous decrease in blood pressure , shock , multi-organ failure , and potentially , death .", "hl_sentences": "The mechanism of T cell activation by superantigens involves their simultaneous binding to MHC II molecules of APCs and the variable region of the TCR β chain . The result is an excessive , uncontrolled release of cytokines , often called a cytokine storm , which stimulates an excessive inflammatory response .", "question": { "cloze_format": "A superantigen is ___.", "normal_format": "What is a superantigen?", "question_choices": [ "a protein that is highly efficient at stimulating a single type of productive and specific T cell response", "a protein produced by antigen-presenting cells to enhance their presentation capabilities", "a protein produced by T cells as a way of increasing the antigen activation they receive from antigen-presenting cells", "a protein that activates T cells in a nonspecific and uncontrolled manner" ], "question_id": "fs-id11676603890420", "question_text": "What is a superantigen?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 1, "ans_text": "B" }, "bloom": null, "hl_context": "<hl> Helper T cells can only be activated by APCs presenting processed foreign epitopes in association with MHC II . <hl> <hl> The first step in the activation process is TCR recognition of the specific foreign epitope presented within the MHC II antigen-binding cleft . <hl> <hl> The second step involves the interaction of CD4 on the helper T cell with a region of the MHC II molecule separate from the antigen-binding cleft . <hl> This second interaction anchors the MHC II-TCR complex and ensures that the helper T cell is recognizing both the foreign ( “ nonself ” ) epitope and “ self ” antigen of the APC ; both recognitions are required for activation of the cell . In the third step , the APC and T cell secrete cytokines that activate the helper T cell . The activated helper T cell then proliferates , dividing by mitosis to produce clonal naïve helper T cells that differentiate into subtypes with different functions ( Figure 18.17 ) .", "hl_sentences": "Helper T cells can only be activated by APCs presenting processed foreign epitopes in association with MHC II . The first step in the activation process is TCR recognition of the specific foreign epitope presented within the MHC II antigen-binding cleft . The second step involves the interaction of CD4 on the helper T cell with a region of the MHC II molecule separate from the antigen-binding cleft .", "question": { "cloze_format": "The TCR of a helper T cell binds ___ .", "normal_format": "To what does the TCR of a helper T cell bind?", "question_choices": [ "antigens presented with MHC I molecules", "antigens presented with MHC II molecules", "free antigen in a soluble form", "haptens only" ], "question_id": "fs-id1167662849721", "question_text": "To what does the TCR of a helper T cell bind?" }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 0, "ans_text": "A" }, "bloom": null, "hl_context": "<hl> Helper T cells can only be activated by APCs presenting processed foreign epitopes in association with MHC II . <hl> <hl> The first step in the activation process is TCR recognition of the specific foreign epitope presented within the MHC II antigen-binding cleft . <hl> <hl> The second step involves the interaction of CD4 on the helper T cell with a region of the MHC II molecule separate from the antigen-binding cleft . <hl> This second interaction anchors the MHC II-TCR complex and ensures that the helper T cell is recognizing both the foreign ( “ nonself ” ) epitope and “ self ” antigen of the APC ; both recognitions are required for activation of the cell . In the third step , the APC and T cell secrete cytokines that activate the helper T cell . The activated helper T cell then proliferates , dividing by mitosis to produce clonal naïve helper T cells that differentiate into subtypes with different functions ( Figure 18.17 ) .", "hl_sentences": "Helper T cells can only be activated by APCs presenting processed foreign epitopes in association with MHC II . The first step in the activation process is TCR recognition of the specific foreign epitope presented within the MHC II antigen-binding cleft . The second step involves the interaction of CD4 on the helper T cell with a region of the MHC II molecule separate from the antigen-binding cleft .", "question": { "cloze_format": "Cytotoxic T cells will bind with their TCR to ___ .", "normal_format": "Cytotoxic T cells will bind with their TCR to which of the following?", "question_choices": [ "antigens presented with MHC I molecules", "antigens presented with MHC II molecules", "free antigen in a soluble form", "haptens only" ], "question_id": "fs-id1167662684321", "question_text": "Cytotoxic T cells will bind with their TCR to which of the following?" }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 3, "ans_text": "D" }, "bloom": null, "hl_context": "<hl> All T cells produce cluster of differentiation ( CD ) molecules , cell surface glycoproteins that can be used to identify and distinguish between the various types of white blood cells . <hl> Although T cells can produce a variety of CD molecules , CD4 and CD8 are the two most important used for differentiation of the classes . Helper T cells and regulatory T cells are characterized by the expression of CD4 on their surface , whereas cytotoxic T cells are characterized by the expression of CD8 .", "hl_sentences": "All T cells produce cluster of differentiation ( CD ) molecules , cell surface glycoproteins that can be used to identify and distinguish between the various types of white blood cells .", "question": { "cloze_format": "A ________ molecule is a glycoprotein used to identify and distinguish white blood cells.", "normal_format": "Which molecule is a glycoprotein used to identify and distinguish white blood cells?\n", "question_choices": [ "T-cell receptor", "B-cell receptor", "MHC I", "cluster of differentiation" ], "question_id": "fs-id1167660257688", "question_text": "A ________ molecule is a glycoprotein used to identify and distinguish white blood cells." }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 1, "ans_text": "B" }, "bloom": null, "hl_context": "<hl> T H 2 cells play an important role in orchestrating the humoral immune response through their secretion of cytokines that activate B cells and direct B cell differentiation and antibody production . <hl> Various cytokines produced by T H 2 cells orchestrate antibody class switching , which allows B cells to switch between the production of IgM , IgG , IgA , and IgE as needed to carry out specific antibody functions and to provide pathogen-specific humoral immune responses .", "hl_sentences": "T H 2 cells play an important role in orchestrating the humoral immune response through their secretion of cytokines that activate B cells and direct B cell differentiation and antibody production .", "question": { "cloze_format": "The T helper cell subset involved in antibody production is ___.", "normal_format": "Name the T helper cell subset involved in antibody production.", "question_choices": [ "TH1", "TH2", "TH17", "CTL" ], "question_id": "fs-id1167662795181", "question_text": "Name the T helper cell subset involved in antibody production." }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 2, "ans_text": "C" }, "bloom": null, "hl_context": "Activation of B cells occurs through different mechanisms depending on the molecular class of the antigen . Activation of a B cell by a protein antigen requires the B cell to function as an APC , presenting the protein epitopes with MHC II to helper T cells . <hl> Because of their dependence on T cells for activation of B cells , protein antigens are classified as T-dependent antigens . <hl> In contrast , polysaccharides , lipopolysaccharides , and other nonprotein antigens are considered T-independent antigens because they can activate B cells without antigen processing and presentation to T cells .", "hl_sentences": "Because of their dependence on T cells for activation of B cells , protein antigens are classified as T-dependent antigens .", "question": { "cloze_format": "___ would be a T-dependent antigen.", "normal_format": "Which of the following would be a T-dependent antigen?", "question_choices": [ "lipopolysaccharide", "glycolipid", "protein", "carbohydrate" ], "question_id": "fs-id1167663529755", "question_text": "Which of the following would be a T-dependent antigen?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 3, "ans_text": "D" }, "bloom": null, "hl_context": "Like T cells , B cells possess antigen-specific receptors with diverse specificities . Although they rely on T cells for optimum function , B cells can be activated without help from T cells . <hl> B-cell receptors ( BCRs ) for naïve mature B cells are membrane-bound monomeric forms of IgD and IgM . <hl> They have two identical heavy chains and two identical light chains connected by disulfide bonds into a basic “ Y ” shape ( Figure 18.20 ) . The trunk of the Y-shaped molecule , the constant region of the two heavy chains , spans the B cell membrane . The two antigen-binding sites exposed to the exterior of the B cell are involved in the binding of specific pathogen epitopes to initiate the activation process . It is estimated that each naïve mature B cell has upwards of 100,000 BCRs on its membrane , and each of these BCRs has an identical epitope-binding specificity .", "hl_sentences": "B-cell receptors ( BCRs ) for naïve mature B cells are membrane-bound monomeric forms of IgD and IgM .", "question": { "cloze_format": "___ would be a BCR.", "normal_format": "Which of the following would be a BCR?", "question_choices": [ "CD4", "MHC II", "MHC I", "IgD" ], "question_id": "fs-id1167661419638", "question_text": "Which of the following would be a BCR?" }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 1, "ans_text": "B" }, "bloom": null, "hl_context": "T cell-dependent activation of B cells plays an important role in both the primary and secondary responses associated with adaptive immunity . With the first exposure to a protein antigen , a T cell-dependent primary antibody response occurs . The initial stage of the primary response is a lag period , or latent period , of approximately 10 days , during which no antibody can be detected in serum . <hl> This lag period is the time required for all of the steps of the primary response , including naïve mature B cell binding of antigen with BCRs , antigen processing and presentation , helper T cell activation , B cell activation , and clonal proliferation . <hl> The end of the lag period is characterized by a rise in IgM levels in the serum , as T H 2 cells stimulate B cell differentiation into plasma cells . IgM levels reach their peak around 14 days after primary antigen exposure ; at about this same time , T H 2 stimulates antibody class switching , and IgM levels in serum begin to decline . Meanwhile , levels of IgG increase until they reach a peak about three weeks into the primary response ( Figure 18.23 ) .", "hl_sentences": "This lag period is the time required for all of the steps of the primary response , including naïve mature B cell binding of antigen with BCRs , antigen processing and presentation , helper T cell activation , B cell activation , and clonal proliferation .", "question": { "cloze_format": "(The) ___ does not occur during the lag period of the primary antibody response.", "normal_format": "Which of the following does not occur during the lag period of the primary antibody response?", "question_choices": [ "activation of helper T cells", "class switching to IgG", "presentation of antigen with MHC II", "binding of antigen to BCRs" ], "question_id": "fs-id1167661409386", "question_text": "Which of the following does not occur during the lag period of the primary antibody response?" }, "references_are_paraphrase": 0 } ]
18
18.1 Overview of Specific Adaptive Immunity Learning Objectives Define memory, primary response, secondary response, and specificity Distinguish between humoral and cellular immunity Differentiate between antigens, epitopes, and haptens Describe the structure and function of antibodies and distinguish between the different classes of antibodies Clinical Focus Part 1 Olivia, a one-year old infant, is brought to the emergency room by her parents, who report her symptoms: excessive crying, irritability, sensitivity to light, unusual lethargy, and vomiting. A physician feels swollen lymph nodes in Olivia’s throat and armpits. In addition, the area of the abdomen over the spleen is swollen and tender. What do these symptoms suggest? What tests might be ordered to try to diagnose the problem? Jump to the next Clinical Focus box. Adaptive immunity is defined by two important characteristics: specificity and memory . Specificity refers to the adaptive immune system’s ability to target specific pathogens, and memory refers to its ability to quickly respond to pathogens to which it has previously been exposed. For example, when an individual recovers from chickenpox, the body develops a memory of the infection that will specifically protect it from the causative agent, the varicella-zoster virus, if it is exposed to the virus again later. Specificity and memory are achieved by essentially programming certain cells involved in the immune response to respond rapidly to subsequent exposures of the pathogen. This programming occurs as a result of the first exposure to a pathogen or vaccine, which triggers a primary response . Subsequent exposures result in a secondary response that is faster and stronger as a result of the body’s memory of the first exposure ( Figure 18.2 ). This secondary response, however, is specific to the pathogen in question. For example, exposure to one virus (e.g., varicella-zoster virus) will not provide protection against other viral diseases (e.g., measles, mumps, or polio). Adaptive specific immunity involves the actions of two distinct cell types: B lymphocytes ( B cells ) and T lymphocytes ( T cells ). Although B cells and T cells arise from a common hematopoietic stem cell differentiation pathway (see Figure 17.12 ), their sites of maturation and their roles in adaptive immunity are very different. B cells mature in the bone marrow and are responsible for the production of glycoproteins called antibodies , or immunoglobulins . Antibodies are involved in the body’s defense against pathogens and toxins in the extracellular environment. Mechanisms of adaptive specific immunity that involve B cells and antibody production are referred to as humoral immunity . The maturation of T cells occurs in the thymus . T cells function as the central orchestrator of both innate and adaptive immune responses. They are also responsible for destruction of cells infected with intracellular pathogens. The targeting and destruction of intracellular pathogens by T cells is called cell-mediated immunity, or cellular immunity . Check Your Understanding List the two defining characteristics of adaptive immunity. Explain the difference between a primary and secondary immune response. How do humoral and cellular immunity differ? Antigens Activation of the adaptive immune defenses is triggered by pathogen-specific molecular structures called antigens . Antigens are similar to the pathogen-associated molecular patterns (PAMPs) discussed in Pathogen Recognition and Phagocytosis ; however, whereas PAMPs are molecular structures found on numerous pathogens, antigens are unique to a specific pathogen. The antigens that stimulate adaptive immunity to chickenpox, for example, are unique to the varicella-zoster virus but significantly different from the antigens associated with other viral pathogens. The term antigen was initially used to describe molecules that stimulate the production of antibodies; in fact, the term comes from a combination of the words anti body and gen erator, and a molecule that stimulates antibody production is said to be antigenic . However, the role of antigens is not limited to humoral immunity and the production of antibodies; antigens also play an essential role in stimulating cellular immunity, and for this reason antigens are sometimes more accurately referred to as immunogens . In this text, however, we will typically refer to them as antigens. Pathogens possess a variety of structures that may contain antigens. For example, antigens from bacterial cells may be associated with their capsules, cell walls, fimbriae, flagella, or pili. Bacterial antigens may also be associated with extracellular toxins and enzymes that they secrete. Viruses possess a variety of antigens associated with their capsids, envelopes, and the spike structures they use for attachment to cells. Antigens may belong to any number of molecular classes, including carbohydrates, lipids, nucleic acids, proteins, and combinations of these molecules. Antigens of different classes vary in their ability to stimulate adaptive immune defenses as well as in the type of response they stimulate (humoral or cellular). The structural complexity of an antigenic molecule is an important factor in its antigenic potential. In general, more complex molecules are more effective as antigens. For example, the three-dimensional complex structure of proteins make them the most effective and potent antigens, capable of stimulating both humoral and cellular immunity. In comparison, carbohydrates are less complex in structure and therefore less effective as antigens; they can only stimulate humoral immune defenses. Lipids and nucleic acids are the least antigenic molecules, and in some cases may only become antigenic when combined with proteins or carbohydrates to form glycolipids, lipoproteins, or nucleoproteins. One reason the three-dimensional complexity of antigens is so important is that antibodies and T cells do not recognize and interact with an entire antigen but with smaller exposed regions on the surface of antigens called epitopes . A single antigen may possess several different epitopes ( Figure 18.3 ), and different antibodies may bind to different epitopes on the same antigen ( Figure 18.4 ). For example, the bacterial flagellum is a large, complex protein structure that can possess hundreds or even thousands of epitopes with unique three-dimensional structures. Moreover, flagella from different bacterial species (or even strains of the same species) contain unique epitopes that can only be bound by specific antibodies. An antigen’s size is another important factor in its antigenic potential. Whereas large antigenic structures like flagella possess multiple epitopes, some molecules are too small to be antigenic by themselves. Such molecules, called haptens , are essentially free epitopes that are not part of the complex three-dimensional structure of a larger antigen. For a hapten to become antigenic, it must first attach to a larger carrier molecule (usually a protein) to produce a conjugate antigen. The hapten-specific antibodies produced in response to the conjugate antigen are then able to interact with unconjugated free hapten molecules. Haptens are not known to be associated with any specific pathogens, but they are responsible for some allergic responses. For example, the hapten urushiol , a molecule found in the oil of plants that cause poison ivy , causes an immune response that can result in a severe rash (called contact dermatitis). Similarly, the hapten penicillin can cause allergic reactions to drugs in the penicillin class. Check Your Understanding What is the difference between an antigen and an epitope? What factors affect an antigen’s antigenic potential? Why are haptens typically not antigenic, and how do they become antigenic? Antibodies Antibodies (also called immunoglobulins) are glycoproteins that are present in both the blood and tissue fluids. The basic structure of an antibody monomer consists of four protein chains held together by disulfide bonds ( Figure 18.5 ). A disulfide bond is a covalent bond between the sulfhydryl R groups found on two cysteine amino acids. The two largest chains are identical to each other and are called the heavy chains . The two smaller chains are also identical to each other and are called the light chains . Joined together, the heavy and light chains form a basic Y-shaped structure. The two ‘arms’ of the Y-shaped antibody molecule are known as the Fab region , for “fragment of antigen binding.” The far end of the Fab region is the variable region, which serves as the site of antigen binding . The amino acid sequence in the variable region dictates the three-dimensional structure, and thus the specific three-dimensional epitope to which the Fab region is capable of binding. Although the epitope specificity of the Fab regions is identical for each arm of a single antibody molecule, this region displays a high degree of variability between antibodies with different epitope specificities. Binding to the Fab region is necessary for neutralization of pathogens, agglutination or aggregation of pathogens, and antibody-dependent cell-mediated cytotoxicity. The constant region of the antibody molecule includes the trunk of the Y and lower portion of each arm of the Y. The trunk of the Y is also called the Fc region , for “fragment of crystallization,” and is the site of complement factor binding and binding to phagocytic cells during antibody-mediated opsonization . Check Your Understanding Describe the different functions of the Fab region and the Fc region. Antibody Classes The constant region of an antibody molecule determines its class, or isotype . The five classes of antibodies are IgG, IgM, IgA, IgD, and IgE. Each class possesses unique heavy chains designated by Greek letters γ, μ, α, δ, and ε, respectively. Antibody classes also exhibit important differences in abundance in serum, arrangement, body sites of action, functional roles, and size ( Figure 18.6 ). IgG is a monomer that is by far the most abundant antibody in human blood, accounting for about 80% of total serum antibody. IgG penetrates efficiently into tissue spaces, and is the only antibody class with the ability to cross the placental barrier , providing passive immunity to the developing fetus during pregnancy. IgG is also the most versatile antibody class in terms of its role in the body’s defense against pathogens. IgM is initially produced in a monomeric membrane-bound form that serves as an antigen-binding receptor on B cells. The secreted form of IgM assembles into a pentamer with five monomers of IgM bound together by a protein structure called the J chain . Although the location of the J chain relative to the Fc regions of the five monomers prevents IgM from performing some of the functions of IgG, the ten available Fab sites associated with a pentameric IgM make it an important antibody in the body’s arsenal of defenses. IgM is the first antibody produced and secreted by B cells during the primary and secondary immune responses, making pathogen-specific IgM a valuable diagnostic marker during active or recent infections. IgA accounts for about 13% of total serum antibody, and secretory IgA is the most common and abundant antibody class found in the mucus secretions that protect the mucous membranes. IgA can also be found in other secretions such as breast milk , tears , and saliva . Secretory IgA is assembled into a dimeric form with two monomers joined by a protein structure called the secretory component. One of the important functions of secretory IgA is to trap pathogens in mucus so that they can later be eliminated from the body. Similar to IgM, IgD is a membrane-bound monomer found on the surface of B cells, where it serves as an antigen-binding receptor. However, IgD is not secreted by B cells, and only trace amounts are detected in serum. These trace amounts most likely come from the degradation of old B cells and the release of IgD molecules from their cytoplasmic membranes. IgE is the least abundant antibody class in serum. Like IgG, it is secreted as a monomer, but its role in adaptive immunity is restricted to anti-parasitic defenses . The Fc region of IgE binds to basophils and mast cells . The Fab region of the bound IgE then interacts with specific antigen epitopes, causing the cells to release potent pro-inflammatory mediators. The inflammatory reaction resulting from the activation of mast cells and basophils aids in the defense against parasites, but this reaction is also central to allergic reactions (see Diseases of the Immune System . Check Your Understanding What part of an antibody molecule determines its class? What class of antibody is involved in protection against parasites? Describe the difference in structure between IgM and IgG. Antigen-Antibody Interactions Different classes of antibody play important roles in the body’s defense against pathogens. These functions include neutralization of pathogens, opsonization for phagocytosis, agglutination, complement activation, and antibody-dependent cell-mediated cytotoxicity. For most of these functions, antibodies also provide an important link between adaptive specific immunity and innate nonspecific immunity. Neutralization involves the binding of certain antibodies (IgG, IgM, or IgA) to epitopes on the surface of pathogens or toxins, preventing their attachment to cells. For example, Secretory IgA can bind to specific pathogens and block initial attachment to intestinal mucosal cells. Similarly, specific antibodies can bind to certain toxins, blocking them from attaching to target cells and thus neutralizing their toxic effects. Viruses can be neutralized and prevented from infecting a cell by the same mechanism ( Figure 18.7 ). As described in Chemical Defenses , opsonization is the coating of a pathogen with molecules, such as complement factors, C-reactive protein , and serum amyloid A , to assist in phagocyte binding to facilitate phagocytosis . IgG antibodies also serve as excellent opsonins, binding their Fab sites to specific epitopes on the surface of pathogens. Phagocytic cells such as macrophages , dendritic cells , and neutrophils have receptors on their surfaces that recognize and bind to the Fc portion of the IgG molecules; thus, IgG helps such phagocytes attach to and engulf the pathogens they have bound ( Figure 18.8 ). Agglutination or aggregation involves the cross-linking of pathogens by antibodies to create large aggregates ( Figure 18.9 ). IgG has two Fab antigen-binding sites , which can bind to two separate pathogen cells, clumping them together. When multiple IgG antibodies are involved, large aggregates can develop; these aggregates are easier for the kidneys and spleen to filter from the blood and easier for phagocytes to ingest for destruction. The pentameric structure of IgM provides ten Fab binding sites per molecule, making it the most efficient antibody for agglutination. Another important function of antibodies is activation of the complement cascade . As discussed in the previous chapter, the complement system is an important component of the innate defenses, promoting the inflammatory response, recruiting phagocytes to site of infection, enhancing phagocytosis by opsonization, and killing gram-negative bacterial pathogens with the membrane attack complex (MAC) . Complement activation can occur through three different pathways (see Figure 17.9 ), but the most efficient is the classical pathway , which requires the initial binding of IgG or IgM antibodies to the surface of a pathogen cell, allowing for recruitment and activation of the C1 complex . Yet another important function of antibodies is antibody-dependent cell-mediated cytotoxicity (ADCC) , which enhances killing of pathogens that are too large to be phagocytosed. This process is best characterized for natural killer cells ( NK cells ), as shown in Figure 18.10 , but it can also involve macrophages and eosinophils . ADCC occurs when the Fab region of an IgG antibody binds to a large pathogen; Fc receptors on effector cells (e.g., NK cells) then bind to the Fc region of the antibody, bringing them into close proximity with the target pathogen. The effector cell then secretes powerful cytotoxins (e.g., perforin and granzymes ) that kill the pathogen. Check Your Understanding Where is IgA normally found? Which class of antibody crosses the placenta, providing protection to the fetus? Compare the mechanisms of opsonization and antibody-dependent cell-mediated cytotoxicity. 18.2 Major Histocompatibility Complexes and Antigen-Presenting Cells Learning Objectives Identify cells that express MHC I and/or MHC II molecules and describe the structures and cellular location of MHC I and MHC II molecules Identify the cells that are antigen-presenting cells Describe the process of antigen processing and presentation with MHC I and MHC II As discussed in Cellular Defenses , major histocompatibility complex (MHC) molecules are expressed on the surface of healthy cells, identifying them as normal and “self” to natural killer (NK) cells . MHC molecules also play an important role in the presentation of foreign antigens, which is a critical step in the activation of T cells and thus an important mechanism of the adaptive immune system. Major Histocompatibility Complex Molecules The major histocompatibility complex ( MHC ) is a collection of genes coding for MHC molecules found on the surface of all nucleated cells of the body. In humans, the MHC genes are also referred to as human leukocyte antigen (HLA) genes . Mature red blood cells , which lack a nucleus, are the only cells that do not express MHC molecules on their surface. There are two classes of MHC molecules involved in adaptive immunity, MHC I and MHC II ( Figure 18.11 ). MHC I molecules are found on all nucleated cells; they present normal self-antigens as well as abnormal or nonself pathogens to the effector T cells involved in cellular immunity. In contrast, MHC II molecules are only found on macrophages , dendritic cells , and B cells ; they present abnormal or nonself pathogen antigens for the initial activation of T cells. Both types of MHC molecules are transmembrane glycoproteins that assemble as dimers in the cytoplasmic membrane of cells, but their structures are quite different. MHC I molecules are composed of a longer α protein chain coupled with a smaller β 2 microglobulin protein, and only the α chain spans the cytoplasmic membrane. The α chain of the MHC I molecule folds into three separate domains: α 1 , α 2 and α 3 . MHC II molecules are composed of two protein chains (an α and a β chain) that are approximately similar in length. Both chains of the MHC II molecule possess portions that span the plasma membrane, and each chain folds into two separate domains: α 1 and α 2 , and β 1 , and β 2 . In order to present abnormal or non-self-antigens to T cells, MHC molecules have a cleft that serves as the antigen-binding site near the “top” (or outermost) portion of the MHC-I or MHC-II dimer. For MHC I, the antigen-binding cleft is formed by the α 1 and α 2 domains, whereas for MHC II, the cleft is formed by the α 1 and β 1 domains ( Figure 18.11 ). Check Your Understanding Compare the structures of the MHC I and MHC II molecules. Antigen-Presenting Cells (APCs) All nucleated cells in the body have mechanisms for processing and presenting antigens in association with MHC molecules. This signals the immune system, indicating whether the cell is normal and healthy or infected with an intracellular pathogen. However, only macrophages, dendritic cells, and B cells have the ability to present antigens specifically for the purpose of activating T cells; for this reason, these types of cells are sometimes referred to as antigen-presenting cells (APCs) . While all APCs play a similar role in adaptive immunity, there are some important differences to consider. Macrophages and dendritic cells are phagocytes that ingest and kill pathogens that penetrate the first-line barriers (i.e., skin and mucous membranes). B cells, on the other hand, do not function as phagocytes but play a primary role in the production and secretion of antibodies. In addition, whereas macrophages and dendritic cells recognize pathogens through nonspecific receptor interactions (e.g., PAMPs , toll-like receptors , and receptors for opsonizing complement or antibody), B cells interact with foreign pathogens or their free antigens using antigen-specific immunoglobulin as receptors (monomeric IgD and IgM ). When the immunoglobulin receptors bind to an antigen, the B cell internalizes the antigen by endocytosis before processing and presentting the antigen to T cells. Antigen Presentation with MHC II Molecules MHC II molecules are only found on the surface of APCs. Macrophages and dendritic cells use similar mechanisms for processing and presentation of antigens and their epitopes in association with MHC II; B cells use somewhat different mechanisms that will be described further in B Lymphocytes and Humoral Immunity . For now, we will focus on the steps of the process as they pertain to dendritic cells. After a dendritic cell recognizes and attaches to a pathogen cell, the pathogen is internalized by phagocytosis and is initially contained within a phagosome . Lysosomes containing antimicrobial enzymes and chemicals fuse with the phagosome to create a phagolysosome, where degradation of the pathogen for antigen processing begins. Proteases (protein-degrading) are especially important in antigen processing because only protein antigen epitopes are presented to T cells by MHC II ( Figure 18.12 ). APCs do not present all possible epitopes to T cells; only a selection of the most antigenic or immunodominant epitopes are presented. The mechanism by which epitopes are selected for processing and presentation by an APC is complicated and not well understood; however, once the most antigenic, immunodominant epitopes have been processed, they associate within the antigen-binding cleft of MHC II molecules and are translocated to the cell surface of the dendritic cell for presentation to T cells. Check Your Understanding What are the three kinds of APCs? What role to MHC II molecules play in antigen presentation? What is the role of antigen presentation in adaptive immunity? Antigen Presentation with MHC I Molecules MHC I molecules, found on all normal, healthy, nucleated cells , signal to the immune system that the cell is a normal “self” cell. In a healthy cell, proteins normally found in the cytoplasm are degraded by proteasomes (enzyme complexes responsible for degradation and processing of proteins) and processed into self-antigen epitopes ; these self-antigen epitopes bind within the MHC I antigen-binding cleft and are then presented on the cell surface. Immune cells, such as NK cells, recognize these self-antigens and do not target the cell for destruction. However, if a cell becomes infected with an intracellular pathogen (e.g., a virus), protein antigens specific to the pathogen are processed in the proteasomes and bind with MHC I molecules for presentation on the cell surface. This presentation of pathogen-specific antigens with MHC I signals that the infected cell must be targeted for destruction along with the pathogen. Before elimination of infected cells can begin, APCs must first activate the T cells involved in cellular immunity. If an intracellular pathogen directly infects the cytoplasm of an APC, then the processing and presentation of antigens can occur as described (in proteasomes and on the cell surface with MHC I). However, if the intracellular pathogen does not directly infect APCs, an alternative strategy called cross-presentation is utilized. In cross-presentation, antigens are brought into the APC by mechanisms normally leading to presentation with MHC II (i.e., through phagocytosis), but the antigen is presented on an MHC I molecule for CD8 T cells. The exact mechanisms by which cross-presentation occur are not yet well understood, but it appears that cross-presentation is primarily a function of dendritic cells and not macrophages or B cells. Check Your Understanding Compare and contrast antigen processing and presentation associated with MHC I and MHC II molecules. What is cross-presentation, and when is it likely to occur? 18.3 T Lymphocytes and Cellular Immunity Learning Objectives Describe the process of T-cell maturation and thymic selection Explain the genetic events that lead to diversity of T-cell receptors Compare and contrast the various classes and subtypes of T cells in terms of activation and function Explain the mechanism by which superantigens effect unregulated T-cell activation As explained in Overview of Specific Adaptive Immunity , the antibodies involved in humoral immunity often bind pathogens and toxins before they can attach to and invade host cells. Thus, humoral immunity is primarily concerned with fighting pathogens in extracellular spaces. However, pathogens that have already gained entry to host cells are largely protected from the humoral antibody-mediated defenses. Cellular immunity, on the other hand, targets and eliminates intracellular pathogens through the actions of T lymphocytes, or T cells ( Figure 18.13 ). T cells also play a more central role in orchestrating the overall adaptive immune response (humoral as well as cellular) along with the cellular defenses of innate immunity. T Cell Production and Maturation T cells, like all other white blood cells involved in innate and adaptive immunity, are formed from multipotent hematopoietic stem cells (HSCs) in the bone marrow (see Figure 17.12 ). However, unlike the white blood cells of innate immunity, eventual T cells differentiate first into lymphoid stem cells that then become small, immature lymphocytes, sometimes called lymphoblasts . The first steps of differentiation occur in the red marrow of bones ( Figure 18.14 ), after which immature T lymphocytes enter the bloodstream and travel to the thymus for the final steps of maturation ( Figure 18.15 ). Once in the thymus, the immature T lymphocytes are referred to as thymocytes . The maturation of thymocytes within the thymus can be divided into three critical steps of positive and negative selection, collectively referred to as thymic selection . The first step of thymic selection occurs in the cortex of the thymus and involves the development of a functional T-cell receptor (TCR) that is required for activation by APCs. Thymocytes with defective TCRs are removed by negative selection through the induction of apoptosis (programmed controlled cell death). The second step of thymic selection also occurs in the cortex and involves the positive selection of thymocytes that will interact appropriately with MHC molecules. Thymocytes that can interact appropriately with MHC molecules receive a positive stimulation that moves them further through the process of maturation, whereas thymocytes that do not interact appropriately are not stimulated and are eliminated by apoptosis . The third and final step of thymic selection occurs in both the cortex and medulla and involves negative selection to remove self-reacting thymocytes , those that react to self-antigens, by apoptosis. This final step is sometimes referred to as central tolerance because it prevents self-reacting T cells from reaching the bloodstream and potentially causing autoimmune disease , which occurs when the immune system attacks healthy “self” cells. Despite central tolerance, some self-reactive T cells generally escape the thymus and enter the peripheral bloodstream. Therefore, a second line of defense called peripheral tolerance is needed to protect against autoimmune disease. Peripheral tolerance involves mechanisms of anergy and inhibition of self-reactive T cells by regulatory T cells . Anergy refers to a state of nonresponsiveness to antigen stimulation. In the case of self-reactive T cells that escape the thymus, lack of an essential co-stimulatory signal required for activation causes anergy and prevents autoimmune activation. Regulatory T cells participate in peripheral tolerance by inhibiting the activation and function of self-reactive T cells and by secreting anti-inflammatory cytokines. It is not completely understood what events specifically direct maturation of thymocytes into regulatory T cells. Current theories suggest the critical events may occur during the third step of thymic selection, when most self-reactive T cells are eliminated. Regulatory T cells may receive a unique signal that is below the threshold required to target them for negative selection and apoptosis. Consequently, these cells continue to mature and then exit the thymus, armed to inhibit the activation of self-reactive T cells. It has been estimated that the three steps of thymic selection eliminate 98% of thymocytes. The remaining 2% that exit the thymus migrate through the bloodstream and lymphatic system to sites of secondary lymphoid organs/tissues, such as the lymph nodes , spleen , and tonsils ( Figure 18.15 ), where they await activation through the presentation of specific antigens by APCs. Until they are activated, they are known as mature naïve T cells . Check Your Understanding What anatomical sites are involved in T cell production and maturation? What are the three steps involved in thymic selection? Why are central tolerance and peripheral tolerance important? What do they prevent? Classes of T Cells T cells can be categorized into three distinct classes: helper T cells , regulatory T cells, and cytotoxic T cells . These classes are differentiated based on their expression of certain surface molecules, their mode of activation, and their functional roles in adaptive immunity ( Table 18.1 ). All T cells produce cluster of differentiation (CD) molecules , cell surface glycoproteins that can be used to identify and distinguish between the various types of white blood cells. Although T cells can produce a variety of CD molecules, CD4 and CD8 are the two most important used for differentiation of the classes. Helper T cells and regulatory T cells are characterized by the expression of CD4 on their surface, whereas cytotoxic T cells are characterized by the expression of CD8. Classes of T cells can also be distinguished by the specific MHC molecules and APCs with which they interact for activation. Helper T cells and regulatory T cells can only be activated by APCs presenting antigens associated with MHC II . In contrast, cytotoxic T cells recognize antigens presented in association with MHC I , either by APCs or by nucleated cells infected with an intracellular pathogen. The different classes of T cells also play different functional roles in the immune system. Helper T cells serve as the central orchestrators that help activate and direct functions of humoral and cellular immunity. In addition, helper T cells enhance the pathogen-killing functions of macrophages and NK cells of innate immunity. In contrast, the primary role of regulatory T cells is to prevent undesirable and potentially damaging immune responses. Their role in peripheral tolerance , for example, protects against autoimmune disorders , as discussed earlier. Finally, cytotoxic T cells are the primary effector cells for cellular immunity. They recognize and target cells that have been infected by intracellular pathogens , destroying infected cells along with the pathogens inside. Classes of T Cells Class Surface CD Molecules Activation Functions Helper T cells CD4 APCs presenting antigens associated with MHC II Orchestrate humoral and cellular immunity Involved in the activation of macrophages and NK cells Regulatory T cells CD4 APCs presenting antigens associated with MHC II Involved in peripheral tolerance and prevention of autoimmune responses Cytotoxic T cells CD8 APCs or infected nucleated cells presenting antigens associated with MHC I Destroy cells infected with intracellular pathogens Table 18.1 Check Your Understanding What are the unique functions of the three classes of T cells? Which T cells can be activated by antigens presented by cells other than APCs? T-Cell Receptors For both helper T cells and cytotoxic T cells, activation is a complex process that requires the interactions of multiple molecules and exposure to cytokines. The T-cell receptor (TCR) is involved in the first step of pathogen epitope recognition during the activation process. The TCR comes from the same receptor family as the antibodies IgD and IgM, the antigen receptors on the B cell membrane surface, and thus shares common structural elements. Similar to antibodies, the TCR has a variable region and a constant region , and the variable region provides the antigen-binding site ( Figure 18.16 ). However, the structure of TCR is smaller and less complex than the immunoglobulin molecules ( Figure 18.5 ). Whereas immunoglobulins have four peptide chains and Y-shaped structures, the TCR consists of just two peptide chains (α and β chains), both of which span the cytoplasmic membrane of the T cell. TCRs are epitope-specific, and it has been estimated that 25 million T cells with unique epitope-binding TCRs are required to protect an individual against a wide range of microbial pathogens. Because the human genome only contains about 25,000 genes, we know that each specific TCR cannot be encoded by its own set of genes. This raises the question of how such a vast population of T cells with millions of specific TCRs can be achieved. The answer is a process called genetic rearrangement , which occurs in the thymus during the first step of thymic selection . The genes that code for the variable regions of the TCR are divided into distinct gene segments called variable (V), diversity (D), and joining (J) segments . The genes segments associated with the α chain of the TCR consist 70 or more different V α segments and 61 different J α segments. The gene segments associated with the β chain of the TCR consist of 52 different V β segments, two different D β segments, and 13 different J β segments. During the development of the functional TCR in the thymus, genetic rearrangement in a T cell brings together one V α segment and one J α segment to code for the variable region of the α chain. Similarly, genetic rearrangement brings one of the V β segments together with one of the D β segments and one of thetJ β segments to code for the variable region of the β chain. All the possible combinations of rearrangements between different segments of V, D, and J provide the genetic diversity required to produce millions of TCRs with unique epitope-specific variable regions. Check Your Understanding What are the similarities and differences between TCRs and immunoglobulins? What process is used to provide millions of unique TCR binding sites? Activation and Differentiation of Helper T Cells Helper T cells can only be activated by APCs presenting processed foreign epitopes in association with MHC II . The first step in the activation process is TCR recognition of the specific foreign epitope presented within the MHC II antigen-binding cleft . The second step involves the interaction of CD4 on the helper T cell with a region of the MHC II molecule separate from the antigen-binding cleft. This second interaction anchors the MHC II-TCR complex and ensures that the helper T cell is recognizing both the foreign (“nonself”) epitope and “self” antigen of the APC; both recognitions are required for activation of the cell. In the third step, the APC and T cell secrete cytokines that activate the helper T cell. The activated helper T cell then proliferates, dividing by mitosis to produce clonal naïve helper T cells that differentiate into subtypes with different functions ( Figure 18.17 ). Activated helper T cells can differentiate into one of four distinct subtypes, summarized in Table 18.2 . The differentiation process is directed by APC-secreted cytokines . Depending on which APC-secreted cytokines interact with an activated helper T cell, the cell may differentiate into a T helper 1 (T H 1) cell, a T helper 2 (T H 2) cell, or a memory helper T cell. The two types of helper T cells are relatively short-lived effector cells , meaning that they perform various functions of the immediate immune response. In contrast, memory helper T cells are relatively long lived; they are programmed to “remember” a specific antigen or epitope in order to mount a rapid, strong, secondary response to subsequent exposures. T H 1 cells secrete their own cytokines that are involved in stimulating and orchestrating other cells involved in adaptive and innate immunity. For example, they stimulate cytotoxic T cells, enhancing their killing of infected cells and promoting differentiation into memory cytotoxic T cells . T H 1 cells also stimulate macrophages and neutrophils to become more effective in their killing of intracellular bacteria. They can also stimulate NK cells to become more effective at killing target cells. T H 2 cells play an important role in orchestrating the humoral immune response through their secretion of cytokines that activate B cells and direct B cell differentiation and antibody production . Various cytokines produced by T H 2 cells orchestrate antibody class switching , which allows B cells to switch between the production of IgM, IgG, IgA, and IgE as needed to carry out specific antibody functions and to provide pathogen-specific humoral immune responses. A third subtype of helper T cells called T H 17 cells was discovered through observations that immunity to some infections is not associated with T H 1 or T H 2 cells. T H 17 cells and the cytokines they produce appear to be specifically responsible for the body’s defense against chronic mucocutaneous infections. Patients who lack sufficient T H 17 cells in the mucosa (e.g., HIV patients) may be more susceptible to bacteremia and gastrointestinal infections. 1 1 Blaschitz C., Raffatellu M. “Th17 cytokines and the gut mucosal barrier.” J Clin Immunol. 2010 Mar; 30(2):196-203. doi: 10.1007/s10875-010-9368-7. Subtypes of Helper T Cells Subtype Functions T H 1 cells Stimulate cytotoxic T cells and produce memory cytotoxic T cells Stimulate macrophages and neutrophils (PMNs) for more effective intracellular killing of pathogens Stimulate NK cells to kill more effectively T H 2 cells Stimulate B cell activation and differentiation into plasma cells and memory B cells Direct antibody class switching in B cells T H 17 cells Stimulate immunity to specific infections such as chronic mucocutaneous infections Memory helper T cells “Remember” a specific pathogen and mount a strong, rapid secondary response upon re-exposure Table 18.2 Activation and Differentiation of Cytotoxic T Cells Cytotoxic T cells (also referred to as cytotoxic T lymphocytes , or CTLs) are activated by APCs in a three-step process similar to that of helper T cells. The key difference is that the activation of cytotoxic T cells involves recognition of an antigen presented with MHC I (as opposed to MHC II) and interaction of CD8 (as opposed to CD4) with the receptor complex. After the successful co-recognition of foreign epitope and self-antigen, the production of cytokines by the APC and the cytotoxic T cell activate clonal proliferation and differentiation. Activated cytotoxic T cells can differentiate into effector cytotoxic T cells that target pathogens for destruction or memory cells that are ready to respond to subsequent exposures. As noted, proliferation and differentiation of cytotoxic T cells is also stimulated by cytokines secreted from T H 1 cells activated by the same foreign epitope. The co-stimulation that comes from these T H 1 cells is provided by secreted cytokines. Although it is possible for activation of cytotoxic T cells to occur without stimulation from T H 1 cells, the activation is not as effective or long-lasting. Once activated, cytotoxic T cells serve as the effector cells of cellular immunity, recognizing and kill cells infected with intracellular pathogens through a mechanism very similar to that of NK cells . However, whereas NK cells recognize nonspecific signals of cell stress or abnormality, cytotoxic T cells recognize infected cells through antigen presentation of pathogen-specific epitopes associated with MHC I . Once an infected cell is recognized, the TCR of the cytotoxic T cell binds to the epitope and releases perforin and granzymes that destroy the infected cell ( Figure 18.18 ). Perforin is a protein that creates pores in the target cell, and granzymes are proteases that enter the pores and induce apoptosis . This mechanism of programmed cell death is a controlled and efficient means of destroying and removing infected cells without releasing the pathogens inside to infect neighboring cells, as might occur if the infected cells were simply lysed. Link to Learning In this video , you can see a cytotoxic T cell inducing apoptosis in a target cell. Check Your Understanding Compare and contrast the activation of helper T cells and cytotoxic T cells. What are the different functions of helper T cell subtypes? What is the mechanism of CTL-mediated destruction of infected cells? Superantigens and Unregulated Activation of T Cells When T cell activation is controlled and regulated, the result is a protective response that is effective in combating infections. However, if T cell activation is unregulated and excessive, the result can be life-threatening. Certain bacterial and viral pathogens produce toxins known as superantigens (see Virulence Factors of Bacterial and Viral Pathogens ) that can trigger such an unregulated response. Known bacterial superantigens include toxic shock syndrome toxin (TSST) , staphylococcal enterotoxins , streptococcal pyrogenic toxins , streptococcal superantigen , and the streptococcal mitogenic exotoxin . Viruses known to produce superantigens include Epstein-Barr virus (human herpesvirus 4), cytomegalovirus (human herpesvirus 5), and others. The mechanism of T cell activation by superantigens involves their simultaneous binding to MHC II molecules of APCs and the variable region of the TCR β chain. This binding occurs outside of the antigen-binding cleft of MHC II, so the superantigen will bridge together and activate MHC II and TCR without specific foreign epitope recognition ( Figure 18.19 ). The result is an excessive, uncontrolled release of cytokines, often called a cytokine storm , which stimulates an excessive inflammatory response. This can lead to a dangerous decrease in blood pressure, shock, multi-organ failure, and potentially, death. Check Your Understanding What are examples of superantigens? How does a superantigen activate a helper T cell? What effect does a superantigen have on a T cell? Case in Point Superantigens Melissa, an otherwise healthy 22-year-old woman, is brought to the emergency room by her concerned boyfriend. She complains of a sudden onset of high fever, vomiting, diarrhea, and muscle aches. In her initial interview, she tells the attending physician that she is on hormonal birth control and also is two days into the menstruation portion of her cycle. She is on no other medications and is not abusing any drugs or alcohol. She is not a smoker. She is not diabetic and does not currently have an infection of any kind to her knowledge. While waiting in the emergency room, Melissa’s blood pressure begins to drop dramatically and her mental state deteriorates to general confusion. The physician believes she is likely suffering from toxic shock syndrome (TSS) . TSS is caused by the toxin TSST-1, a superantigen associated with Staphylococcus aureus , and improper tampon use is a common cause of infections leading to TSS. The superantigen inappropriately stimulates widespread T cell activation and excessive cytokine release, resulting in a massive and systemic inflammatory response that can be fatal. Vaginal or cervical swabs may be taken to confirm the presence of the microbe, but these tests are not critical to perform based on Melissa’s symptoms and medical history. The physician prescribes rehydration, supportive therapy, and antibiotics to stem the bacterial infection. She also prescribes drugs to increase Melissa’s blood pressure. Melissa spends three days in the hospital undergoing treatment; in addition, her kidney function is monitored because of the high risk of kidney failure associated with TSS. After 72 hours, Melissa is well enough to be discharged to continue her recovery at home. In what way would antibiotic therapy help to combat a superantigen? Clinical Focus Part 2 Olivia’s swollen lymph nodes, abdomen, and spleen suggest a strong immune response to a systemic infection in progress. In addition, little Olivia is reluctant to turn her head and appears to be experiencing severe neck pain. The physician orders a complete blood count, blood culture, and lumbar puncture. The cerebrospinal fluid (CSF) obtained appears cloudy and is further evaluated by Gram stain assessment and culturing for potential bacterial pathogens. The complete blood count indicates elevated numbers of white blood cells in Olivia’s bloodstream. The white blood cell increases are recorded at 28.5 K/µL (normal range: 6.0–17.5 K/µL). The neutrophil percentage was recorded as 60% (normal range: 23–45%). Glucose levels in the CSF were registered at 30 mg/100 mL (normal range: 50–80 mg/100 mL). The WBC count in the CSF was 1,163/mm 3 (normal range: 5–20/mm 3 ). Based on these results, do you have a preliminary diagnosis? What is a recommended treatment based on this preliminary diagnosis? Jump to the next Clinical Focus box. Go back to the previous Clinical Focus box. 18.4 B Lymphocytes and Humoral Immunity Learning Objectives Describe the production and maturation of B cells Compare the structure of B-cell receptors and T-cell receptors Compare T-dependent and T-independent activation of B cells Compare the primary and secondary antibody responses Humoral immunity refers to mechanisms of the adaptive immune defenses that are mediated by antibodies secreted by B lymphocytes, or B cells. This section will focus on B cells and discuss their production and maturation, receptors, and mechanisms of activation. B Cell Production and Maturation Like T cells, B cells are formed from multipotent hematopoietic stem cells (HSCs) in the bone marrow and follow a pathway through lymphoid stem cell and lymphoblast (see Figure 17.12 ). Unlike T cells, however, lymphoblasts destined to become B cells do not leave the bone marrow and travel to the thymus for maturation. Rather, eventual B cells continue to mature in the bone marrow. The first step of B cell maturation is an assessment of the functionality of their antigen-binding receptors. This occurs through positive selection for B cells with normal functional receptors. A mechanism of negative selection is then used to eliminate self-reacting B cells and minimize the risk of autoimmunity . Negative selection of self-reacting B cells can involve elimination by apoptosis , editing or modification of the receptors so they are no longer self-reactive, or induction of anergy in the B cell. Immature B cells that pass the selection in the bone marrow then travel to the spleen for their final stages of maturation. There they become naïve mature B cells , i.e., mature B cells that have not yet been activated. Check Your Understanding Compare the maturation of B cells with the maturation of T cells. B-Cell Receptors Like T cells, B cells possess antigen-specific receptors with diverse specificities. Although they rely on T cells for optimum function, B cells can be activated without help from T cells. B-cell receptors (BCRs) for naïve mature B cells are membrane-bound monomeric forms of IgD and IgM . They have two identical heavy chains and two identical light chains connected by disulfide bonds into a basic “Y” shape ( Figure 18.20 ). The trunk of the Y-shaped molecule, the constant region of the two heavy chains, spans the B cell membrane. The two antigen-binding sites exposed to the exterior of the B cell are involved in the binding of specific pathogen epitopes to initiate the activation process. It is estimated that each naïve mature B cell has upwards of 100,000 BCRs on its membrane, and each of these BCRs has an identical epitope-binding specificity. In order to be prepared to react to a wide range of microbial epitopes, B cells, like T cells, use genetic rearrangement of hundreds of gene segments to provide the necessary diversity of receptor specificities. The variable region of the BCR heavy chain is made up of V, D, and J segments , similar to the β chain of the TCR. The variable region of the BCR light chain is made up of V and J segments, similar to the α chain of the TCR. Genetic rearrangement of all possible combinations of V-J-D (heavy chain) and V-J (light chain) provides for millions of unique antigen-binding sites for the BCR and for the antibodies secreted after activation. One important difference between BCRs and TCRs is the way they can interact with antigenic epitopes. Whereas TCRs can only interact with antigenic epitopes that are presented within the antigen-binding cleft of MHC I or MHC II , BCRs do not require antigen presentation with MHC; they can interact with epitopes on free antigens or with epitopes displayed on the surface of intact pathogens. Another important difference is that TCRs only recognize protein epitopes, whereas BCRs can recognize epitopes associated with different molecular classes (e.g., proteins, polysaccharides, lipopolysaccharides). Activation of B cells occurs through different mechanisms depending on the molecular class of the antigen. Activation of a B cell by a protein antigen requires the B cell to function as an APC, presenting the protein epitopes with MHC II to helper T cells. Because of their dependence on T cells for activation of B cells , protein antigens are classified as T-dependent antigens . In contrast, polysaccharides, lipopolysaccharides, and other nonprotein antigens are considered T-independent antigens because they can activate B cells without antigen processing and presentation to T cells. Check Your Understanding What types of molecules serve as the BCR? What are the differences between TCRs and BCRs with respect to antigen recognition? Which molecule classes are T-dependent antigens and which are T-independent antigens? T Cell-Independent Activation of B cells Activation of B cells without the cooperation of helper T cells is referred to as T cell-independent activation and occurs when BCRs interact with T-independent antigens. T-independent antigens (e.g., polysaccharide capsules, lipopolysaccharide) have repetitive epitope units within their structure, and this repetition allows for the cross-linkage of multiple BCRs, providing the first signal for activation ( Figure 18.21 ). Because T cells are not involved, the second signal has to come from other sources, such as interactions of toll-like receptors with PAMPs or interactions with factors from the complement system . Once a B cell is activated, it undergoes clonal proliferation and daughter cells differentiate into plasma cells. Plasma cells are antibody factories that secrete large quantities of antibodies. After differentiation, the surface BCRs disappear and the plasma cell secretes pentameric IgM molecules that have the same antigen specificity as the BCRs ( Figure 18.21 ). The T cell-independent response is short-lived and does not result in the production of memory B cells . Thus it will not result in a secondary response to subsequent exposures to T-independent antigens. Check Your Understanding What are the two signals required for T cell-independent activation of B cells? What is the function of a plasma cell? T Cell-Dependent Activation of B cells T cell-dependent activation of B cells is more complex than T cell-independent activation, but the resulting immune response is stronger and develops memory. T cell-dependent activation can occur either in response to free protein antigens or to protein antigens associated with an intact pathogen. Interaction between the BCRs on a naïve mature B cell and a free protein antigen stimulate internalization of the antigen, whereas interaction with antigens associated with an intact pathogen initiates the extraction of the antigen from the pathogen before internalization. Once internalized inside the B cell, the protein antigen is processed and presented with MHC II . The presented antigen is then recognized by helper T cells specific to the same antigen. The TCR of the helper T cell recognizes the foreign antigen, and the T cell’s CD4 molecule interacts with MHC II on the B cell. The coordination between B cells and helper T cells that are specific to the same antigen is referred to as linked recognition . Once activated by linked recognition, T H 2 cells produce and secrete cytokines that activate the B cell and cause proliferation into clonal daughter cells. After several rounds of proliferation, additional cytokines provided by the T H 2 cells stimulate the differentiation of activated B cell clones into memory B cells , which will quickly respond to subsequent exposures to the same protein epitope, and plasma cells that lose their membrane BCRs and initially secrete pentameric IgM ( Figure 18.22 ). After initial secretion of IgM, cytokines secreted by T H 2 cells stimulate the plasma cells to switch from IgM production to production of IgG , IgA , or IgE . This process, called class switching or isotype switching , allows plasma cells cloned from the same activated B cell to produce a variety of antibody classes with the same epitope specificity. Class switching is accomplished by genetic rearrangement of gene segments encoding the constant region , which determines an antibody’s class. The variable region is not changed, so the new class of antibody retains the original epitope specificity. Check Your Understanding What steps are required for T cell-dependent activation of B cells? What is antibody class switching and why is it important? Primary and Secondary Responses T cell-dependent activation of B cells plays an important role in both the primary and secondary responses associated with adaptive immunity. With the first exposure to a protein antigen, a T cell-dependent primary antibody response occurs. The initial stage of the primary response is a lag period , or latent period , of approximately 10 days, during which no antibody can be detected in serum. This lag period is the time required for all of the steps of the primary response, including naïve mature B cell binding of antigen with BCRs, antigen processing and presentation, helper T cell activation, B cell activation, and clonal proliferation. The end of the lag period is characterized by a rise in IgM levels in the serum, as T H 2 cells stimulate B cell differentiation into plasma cells . IgM levels reach their peak around 14 days after primary antigen exposure; at about this same time, T H 2 stimulates antibody class switching, and IgM levels in serum begin to decline. Meanwhile, levels of IgG increase until they reach a peak about three weeks into the primary response ( Figure 18.23 ). During the primary response, some of the cloned B cells are differentiated into memory B cells programmed to respond to subsequent exposures. This secondary response occurs more quickly and forcefully than the primary response. The lag period is decreased to only a few days and the production of IgG is significantly higher than observed for the primary response ( Figure 18.23 ). In addition, the antibodies produced during the secondary response are more effective and bind with higher affinity to the targeted epitopes. Plasma cells produced during secondary responses live longer than those produced during the primary response, so levels of specific antibody remain elevated for a longer period of time. Check Your Understanding What events occur during the lag period of the primary antibody response? Why do antibody levels remain elevated longer during the secondary antibody response? 18.5 Vaccines Learning Objectives Compare the various kinds of artificial immunity Differentiate between variolation and vaccination Describe different types of vaccines and explain their respective advantages and disadvantages For many diseases, prevention is the best form of treatment, and few strategies for disease prevention are as effective as vaccination. Vaccination is a form of artificial immunity. By artificially stimulating the adaptive immune defenses, a vaccine triggers memory cell production similar to that which would occur during a primary response . In so doing, the patient is able to mount a strong secondary response upon exposure to the pathogen—but without having to first suffer through an initial infection. In this section, we will explore several different kinds of artificial immunity along with various types of vaccines and the mechanisms by which they induce artificial immunity. Classifications of Adaptive Immunity All forms of adaptive immunity can be described as either active or passive. Active immunity refers to the activation of an individual’s own adaptive immune defenses, whereas passive immunity refers to the transfer of adaptive immune defenses from another individual or animal. Active and passive immunity can be further subdivided based on whether the protection is acquired naturally or artificially. Natural active immunity is adaptive immunity that develops after natural exposure to a pathogen ( Figure 18.24 ). Examples would include the lifelong immunity that develops after recovery from a chickenpox or measles infection (although an acute infection is not always necessary to activate adaptive immunity). The length of time that an individual is protected can vary substantially depending upon the pathogen and antigens involved. For example, activation of adaptive immunity by protein spike structures during an intracellular viral infection can activate lifelong immunity, whereas activation by carbohydrate capsule antigens during an extracellular bacterial infection may activate shorter-term immunity. Natural passive immunity involves the natural passage of antibodies from a mother to her child before and after birth. IgG is the only antibody class that can cross the placenta from mother’s blood to the fetal blood supply. Placental transfer of IgG is an important passive immune defense for the infant, lasting up to six months after birth. Secretory IgA can also be transferred from mother to infant through breast milk . Artificial passive immunity refers to the transfer of antibodies produced by a donor (human or animal) to another individual. This transfer of antibodies may be done as a prophylactic measure (i.e., to prevent disease after exposure to a pathogen) or as a strategy for treating an active infection. For example, artificial passive immunity is commonly used for post-exposure prophylaxis against rabies , hepatitis A, hepatitis B , and chickenpox (in high risk individuals). Active infections treated by artificial passive immunity include cytomegalovirus infections in immunocompromised patients and Ebola virus infections. In 1995, eight patients in the Democratic Republic of the Congo with active Ebola infections were treated with blood transfusions from patients who were recovering from Ebola. Only one of the eight patients died (a 12.5% mortality rate), which was much lower than the expected 80% mortality rate for Ebola in untreated patients. 2 Artificial passive immunity is also used for the treatment of diseases caused by bacterial toxins, including tetanus , botulism , and diphtheria . 2 K. Mupapa, M. Massamba, K. Kibadi, K. Kivula, A. Bwaka, M. Kipasa, R. Colebunders, J. J. Muyembe-Tamfum. “Treatment of Ebola Hemorrhagic Fever with Blood Transfusions from Convalescent Patients.” Journal of Infectious Diseases 179 Suppl. (1999): S18–S23. Artificial active immunity is the foundation for vaccination . It involves the activation of adaptive immunity through the deliberate exposure of an individual to weakened or inactivated pathogens, or preparations consisting of key pathogen antigens. Check Your Understanding What is the difference between active and passive immunity? What kind of immunity is conferred by a vaccine? Herd Immunity The four kinds of immunity just described result from an individual’s adaptive immune system. For any given disease, an individual may be considered immune or susceptible depending on his or her ability to mount an effective immune response upon exposure. Thus, any given population is likely to have some individuals who are immune and other individuals who are susceptible. If a population has very few susceptible individuals, even those susceptible individuals will be protected by a phenomenon called herd immunity . Herd immunity has nothing to do with an individual’s ability to mount an effective immune response; rather, it occurs because there are too few susceptible individuals in a population for the disease to spread effectively. Vaccination programs create herd immunity by greatly reducing the number of susceptible individuals in a population. Even if some individuals in the population are not vaccinated, as long as a certain percentage is immune (either naturally or artificially), the few susceptible individuals are unlikely to be exposed to the pathogen. However, because new individuals are constantly entering populations (for example, through birth or relocation), vaccination programs are necessary to maintain herd immunity. Eye on Ethics Vaccination: Obligation or Choice A growing number of parents are choosing not to vaccinate their children. They are dubbed “ antivaxxers ,” and the majority of them believe that vaccines are a cause of autism (or other disease conditions), a link that has now been thoroughly disproven. Others object to vaccines on religious or moral grounds (e.g., the argument that Gardasil vaccination against HPV may promote sexual promiscuity), on personal ethical grounds (e.g., a conscientious objection to any medical intervention), or on political grounds (e.g., the notion that mandatory vaccinations are a violation of individual liberties). 3 3 Elizabeth Yale. “Why Anti-Vaccination Movements Can Never Be Tamed.” Religion & Politics , July 22, 2014. http://religionandpolitics.org/2014/07/22/why-anti-vaccination-movements-can-never-be-tamed. It is believed that this growing number of unvaccinated individuals has led to new outbreaks of whooping cough and measles . We would expect that herd immunity would protect those unvaccinated in our population, but herd immunity can only be maintained if enough individuals are being vaccinated. Vaccination is clearly beneficial for public health. But from the individual parent’s perspective the view can be murkier. Vaccines, like all medical interventions, have associated risks, and while the risks of vaccination may be extremely low compared to the risks of infection, parents may not always understand or accept the consensus of the medical community. Do such parents have a right to withhold vaccination from their children? Should they be allowed to put their children—and society at large—at risk? Many governments insist on childhood vaccinations as a condition for entering public school, but it has become easy in most states to opt out of the requirement or to keep children out of the public system. Since the 1970s, West Virginia and Mississippi have had in place a stringent requirement for childhood vaccination, without exceptions, and neither state has had a case of measles since the early 1990s. California lawmakers recently passed a similar law in response to a measles outbreak in 2015, making it much more difficult for parents to opt out of vaccines if their children are attending public schools. Given this track record and renewed legislative efforts, should other states adopt similarly strict requirements? What role should health-care providers play in promoting or enforcing universal vaccination? Studies have shown that many parents’ minds can be changed in response to information delivered by health-care workers, but is it the place of health-care workers to try to persuade parents to have their children vaccinated? Some health-care providers are understandably reluctant to treat unvaccinated patients. Do they have the right to refuse service to patients who decline vaccines? Do insurance companies have the right to deny coverage to antivaxxers? These are all ethical questions that policymakers may be forced to address as more parents skirt vaccination norms. Variolation and Vaccination Thousands of years ago, it was first recognized that individuals who survived a smallpox infection were immune to subsequent infections. The practice of inoculating individuals to actively protect them from smallpox appears to have originated in the 10 th century in China, when the practice of variolation was described ( Figure 18.25 ). Variolation refers to the deliberate inoculation of individuals with infectious material from scabs or pustules of smallpox victims. Infectious materials were either injected into the skin or introduced through the nasal route. The infection that developed was usually milder than naturally acquired smallpox, and recovery from the milder infection provided protection against the more serious disease. Although the majority of individuals treated by variolation developed only mild infections, the practice was not without risks. More serious and sometimes fatal infections did occur, and because smallpox was contagious, infections resulting from variolation could lead to epidemics. Even so, the practice of variolation for smallpox prevention spread to other regions, including India, Africa, and Europe. Although variolation had been practiced for centuries, the English physician Edward Jenner (1749–1823) is generally credited with developing the modern process of vaccination. Jenner observed that milkmaids who developed cowpox , a disease similar to smallpox but milder, were immune to the more serious smallpox. This led Jenner to hypothesize that exposure to a less virulent pathogen could provide immune protection against a more virulent pathogen, providing a safer alternative to variolation. In 1796, Jenner tested his hypothesis by obtaining infectious samples from a milkmaid’s active cowpox lesion and injecting the materials into a young boy ( Figure 18.26 ). The boy developed a mild infection that included a low-grade fever, discomfort in his axillae (armpit) and loss of appetite. When the boy was later infected with infectious samples from smallpox lesions, he did not contract smallpox. 4 This new approach was termed vaccination , a name deriving from the use of cowpox (Latin vacca meaning “cow”) to protect against smallpox. Today, we know that Jenner’s vaccine worked because the cowpox virus is genetically and antigenically related to the Variola viruses that caused smallpox. Exposure to cowpox antigens resulted in a primary response and the production of memory cells that identical or related epitopes of Variola virus upon a later exposure to smallpox. 4 N. J. Willis. “Edward Jenner and the Eradication of Smallpox.” Scottish Medical Journal 42 (1997): 118–121. The success of Jenner’s smallpox vaccination led other scientists to develop vaccines for other diseases. Perhaps the most notable was Louis Pasteur , who developed vaccines for rabies , cholera , and anthrax . During the 20 th and 21 st centuries, effective vaccines were developed to prevent a wide range of diseases caused by viruses (e.g., chickenpox and shingles, hepatitis, measles, mumps, polio, and yellow fever) and bacteria (e.g., diphtheria, pneumococcal pneumonia, tetanus, and whooping cough,) . Check Your Understanding What is the difference between variolation and vaccination for smallpox? Explain why vaccination is less risky than variolation. Classes of Vaccines For a vaccine to provide protection against a disease, it must expose an individual to pathogen-specific antigens that will stimulate a protective adaptive immune response. By its very nature, this entails some risk. As with any pharmaceutical drug, vaccines have the potential to cause adverse effects. However, the ideal vaccine causes no severe adverse effects and poses no risk of contracting the disease that it is intended to prevent. Various types of vaccines have been developed with these goals in mind. These different classes of vaccines are described in the next section and summarized in Table 18.3 . Live Attenuated Vaccines Live attenuated vaccines expose an individual to a weakened strain of a pathogen with the goal of establishing a subclinical infection that will activate the adaptive immune defenses. Pathogens are attenuated to decrease their virulence using methods such as genetic manipulation (to eliminate key virulence factors) or long-term culturing in an unnatural host or environment (to promote mutations and decrease virulence). By establishing an active infection, live attenuated vaccines stimulate a more comprehensive immune response than some other types of vaccines. Live attenuated vaccines activate both cellular and humoral immunity and stimulate the development of memory for long-lasting immunity. In some cases, vaccination of one individual with a live attenuated pathogen can even lead to natural transmission of the attenuated pathogen to other individuals. This can cause the other individuals to also develop an active, subclinical infection that activates their adaptive immune defenses. Disadvantages associated with live attenuated vaccines include the challenges associated with long-term storage and transport as well as the potential for a patient to develop signs and symptoms of disease during the active infection (particularly in immunocompromised patients). There is also a risk of the attenuated pathogen reverting back to full virulence. Table 18.3 lists examples live attenuated vaccines. Inactivated Vaccines Inactivated vaccines contain whole pathogens that have been killed or inactivated with heat, chemicals, or radiation. For inactivated vaccines to be effective, the inactivation process must not affect the structure of key antigens on the pathogen. Because the pathogen is killed or inactive, inactivated vaccines do not produce an active infection, and the resulting immune response is weaker and less comprehensive than that provoked by a live attenuated vaccine. Typically the response involves only humoral immunity, and the pathogen cannot be transmitted to other individuals. In addition, inactivated vaccines usually require higher doses and multiple boosters, possibly causing inflammatory reactions at the site of injection. Despite these disadvantages, inactivated vaccines do have the advantages of long-term storage stability and ease of transport. Also, there is no risk of causing severe active infections. However, inactivated vaccines are not without their side effects. Table 18.3 lists examples of inactivated vaccines. Subunit Vaccines Whereas live attenuated and inactive vaccines expose an individual to a weakened or dead pathogen, subunit vaccines only expose the patient to the key antigens of a pathogen—not whole cells or viruses. Subunit vaccines can be produced either by chemically degrading a pathogen and isolating its key antigens or by producing the antigens through genetic engineering. Because these vaccines contain only the essential antigens of a pathogen, the risk of side effects is relatively low. Table 18.3 lists examples of subunit vaccines. Toxoid Vaccines Like subunit vaccines, toxoid vaccines do not introduce a whole pathogen to the patient; they contain inactivated bacterial toxins , called toxoids. Toxoid vaccines are used to prevent diseases in which bacterial toxins play an important role in pathogenesis. These vaccines activate humoral immunity that neutralizes the toxins. Table 18.3 lists examples of toxoid vaccines. Conjugate Vaccines A conjugate vaccine is a type of subunit vaccine that consists of a protein conjugated to a capsule polysaccharide. Conjugate vaccines have been developed to enhance the efficacy of subunit vaccines against pathogens that have protective polysaccharide capsules that help them evade phagocytosis , causing invasive infections that can lead to meningitis and other serious conditions. The subunit vaccines against these pathogens introduce T-independent capsular polysaccharide antigens that result in the production of antibodies that can opsonize the capsule and thus combat the infection; however, children under the age of two years do not respond effectively to these vaccines. Children do respond effectively when vaccinated with the conjugate vaccine, in which a protein with T-dependent antigens is conjugated to the capsule polysaccharide. The conjugated protein-polysaccharide antigen stimulates production of antibodies against both the protein and the capsule polysaccharide. Table 18.3 lists examples of conjugate vaccines. Classes of Vaccines Class Description Advantages Disadvantages Examples Live attenuated Weakened strain of whole pathogen Cellular and humoral immunity Difficult to store and transport Chickenpox, German measles, measles, mumps, tuberculosis, typhoid fever, yellow fever Long-lasting immunity Risk of infection in immunocompromised patients Transmission to contacts Risk of reversion Inactivated Whole pathogen killed or inactivated with heat, chemicals, or radiation Ease of storage and transport Weaker immunity (humoral only) Cholera, hepatitis A, influenza, plague, rabies No risk of severe active infection Higher doses and more boosters required Subunit Immunogenic antigens Lower risk of side effects Limited longevity Anthrax, hepatitis B, influenza, meningitis, papillomavirus, pneumococcal pneumonia, whooping cough Multiple doses required No protection against antigenic variation Toxoid Inactivated bacterial toxin Humoral immunity to neutralize toxin Does not prevent infection Botulism, diphtheria, pertussis, tetanus Conjugate Capsule polysaccharide conjugated to protein T-dependent response to capsule Costly to produce Meningitis ( Haemophilus influenzae , Streptococcus pneumoniae , Neisseria meningitides ) No protection against antigenic variation Better response in young children May interfere with other vaccines Table 18.3 Check Your Understanding What is the risk associated with a live attenuated vaccine? Why is a conjugated vaccine necessary in some cases? Micro Connections DNA Vaccines DNA vaccines represent a relatively new and promising approach to vaccination. A DNA vaccine is produced by incorporating genes for antigens into a recombinant plasmid vaccine. Introduction of the DNA vaccine into a patient leads to uptake of the recombinant plasmid by some of the patient’s cells, followed by transcription and translation of antigens and presentation of these antigens with MHC I to activate adaptive immunity. This results in the stimulation of both humoral and cellular immunity without the risk of active disease associated with live attenuated vaccines. Although most DNA vaccines for humans are still in development, it is likely that they will become more prevalent in the near future as researchers are working on engineering DNA vaccines that will activate adaptive immunity against several different pathogens at once. First-generation DNA vaccines tested in the 1990s looked promising in animal models but were disappointing when tested in human subjects. Poor cellular uptake of the DNA plasmids was one of the major problems impacting their efficacy. Trials of second-generation DNA vaccines have been more promising thanks to new techniques for enhancing cellular uptake and optimizing antigens. DNA vaccines for various cancers and viral pathogens such as HIV, HPV, and hepatitis B and C are currently in development. Some DNA vaccines are already in use. In 2005, a DNA vaccine against West Nile virus was approved for use in horses in the United States. Canada has also approved a DNA vaccine to protect fish from infectious hematopoietic necrosis virus. 5 A DNA vaccine against Japanese encephalitis virus was approved for use in humans in 2010 in Australia. 6 5 M. Alonso and J. C. Leong. “Licensed DNA Vaccines Against Infectious Hematopoietic Necrosis Virus (IHNV).” Recent Patents on DNA & Gene Sequences (Discontinued) 7 no. 1 (2013): 62–65, issn 1872-2156/2212-3431. doi 10.2174/1872215611307010009. 6 S.B. Halstead and S. J. Thomas. “New Japanese Encephalitis Vaccines: Alternatives to Production in Mouse Brain.” Expert Review of Vaccines 10 no. 3 (2011): 355–64. Clinical Focus Resolution Based on Olivia’s symptoms, her physician made a preliminary diagnosis of bacterial meningitis without waiting for positive identification from the blood and CSF samples sent to the lab. Olivia was admitted to the hospital and treated with intravenous broad-spectrum antibiotics and rehydration therapy. Over the next several days, her condition began to improve, and new blood samples and lumbar puncture samples showed an absence of microbes in the blood and CSF with levels of white blood cells returning to normal. During this time, the lab produced a positive identification of Neisseria meningitidis , the causative agent of meningococcal meningitis , in her original CSF sample. N. meningitidis produces a polysaccharide capsule that serves as a virulence factor. N. meningitidis tends to affect infants after they begin to lose the natural passive immunity provided by maternal antibodies. At one year of age, Olivia’s maternal IgG antibodies would have disappeared, and she would not have developed memory cells capable of recognizing antigens associated with the polysaccharide capsule of the N. meningitidis. As a result, her adaptive immune system was unable to produce protective antibodies to combat the infection, and without antibiotics she may not have survived. Olivia’s infection likely would have been avoided altogether had she been vaccinated. A conjugate vaccine to prevent meningococcal meningitis is available and approved for infants as young as two months of age. However, current vaccination schedules in the United States recommend that the vaccine be administered at age 11–12 with a booster at age 16. Go back to the previous Clinical Focus box. Link to Learning In countries with developed public health systems, many vaccines are routinely administered to children and adults. Vaccine schedules are changed periodically, based on new information and research results gathered by public health agencies. In the United States, the CDC publishes schedules and other updated information about vaccines.
u.s._history
Summary 15.1 The Origins and Outbreak of the Civil War The election of Abraham Lincoln to the presidency in 1860 proved to be a watershed event. While it did not cause the Civil War, it was the culmination of increasing tensions between the proslavery South and the antislavery North. Before Lincoln had even taken office, seven Deep South states had seceded from the Union to form the CSA, dedicated to maintaining racial slavery and White supremacy. Last-minute efforts to reach a compromise, such as the proposal by Senator Crittenden and the Corwin amendment, went nowhere. The time for compromise had come to an end. With the Confederate attack on Fort Sumter, the Civil War began. 15.2 Early Mobilization and War Many in both the North and the South believed that a short, decisive confrontation in 1861 would settle the question of the Confederacy. These expectations did not match reality, however, and the war dragged on into a second year. Both sides mobilized, with advantages and disadvantages on each side that led to a rough equilibrium. The losses of battles at Manassas and Fredericksburg, Virginia, kept the North from achieving the speedy victory its generals had hoped for, but the Union did make gains and continued to press forward. While they could not capture the Southern capital of Richmond, they were victorious in the Battle of Shiloh and captured New Orleans and Memphis. Thus, the Confederates lost major ground on the western front. 15.3 1863: The Changing Nature of the War The year 1863 proved decisive in the Civil War for two major reasons. First, the Union transformed the purpose of the struggle from restoring the Union to ending slavery. While Lincoln’s Emancipation Proclamation actually succeeded in freeing few of the enslaved, it made freedom for African Americans a cause of the Union. Second, the tide increasingly turned against the Confederacy. The success of the Vicksburg Campaign had given the Union control of the Mississippi River, and Lee’s defeat at Gettysburg had ended the attempted Confederate invasion of the North. 15.4 The Union Triumphant Having failed to win the support it expected from either Great Britain or France, the Confederacy faced a long war with limited resources and no allies. Lincoln won reelection in 1864, and continued to pursue the Union campaign, not only in the east and west, but also with a drive into the South under the leadership of General Sherman, whose March to the Sea through Georgia destroyed everything in its path. Cut off and outnumbered, Confederate general Lee surrendered to Union general Grant on April 9 at Appomattox Court House in Virginia. Within days of Lee’s surrender, Confederate troops had lay down their arms, and the devastating war came to a close.
Chapter Outline 15.1 The Origins and Outbreak of the Civil War 15.2 Early Mobilization and War 15.3 1863: The Changing Nature of the War 15.4 The Union Triumphant Introduction In May 1864, General Ulysses S. Grant ordered the Union’s Army of the Potomac to cross the Rapidan River in Virginia. Grant knew that Confederate general Robert E. Lee would defend the Confederate capital at Richmond at all costs, committing troops that might otherwise be sent to the Shenandoah or the Deep South to stop Union general William Tecumseh Sherman from capturing Atlanta, a key Confederate city. For two days, the Army of the Potomac fought Lee’s troops in the Wilderness, a wooded area along the Rapidan River. Nearly ten thousand Confederate soldiers were killed or wounded, as were more than seventeen thousand Union troops. A few weeks later, the armies would meet again at the Battle of Cold Harbor, where another fifteen thousand men would be wounded or killed. As in many battles, the bodies of those who died were left on the field where they fell. A year later, African Americans, who were often called upon to perform menial labor for the Union army ( Figure 15.1 ), collected the skeletal remains of the dead for a proper burial. The state of the graves of many Civil War soldiers partly inspired the creation of Memorial Day, a day set aside for visiting and decorating the graves of the dead.
[ { "answer": { "ans_choice": 0, "ans_text": "that the Five Civilized Tribes would be admitted into the Confederacy" }, "bloom": null, "hl_context": "<hl> The Confederacy also gained the backing of the Five Civilized Tribes , as they were called , in the Indian Territory . <hl> The Five Civilized Tribes comprised the Choctaws , Chickasaws , Creeks , Seminoles , and Cherokees . The tribes supported slavery and many members were enslavers . These Native American slaveholders , who had been forced from their lands in Georgia and elsewhere in the Deep South during the presidency of Andrew Jackson , now found unprecedented common cause with White slaveholders . The CSA even allowed them to send delegates to the Confederate Congress . Despite the ruptures and tensions , by the 1860s , some hope of healing the nation still existed . Before Lincoln took office , John Crittenden , a senator from Kentucky who had helped form the Constitutional Union Party during the 1860 presidential election , attempted to defuse the explosive situation by offering six constitutional amendments and a series of resolutions , known as the Crittenden Compromise . Crittenden ’ s goal was to keep the South from seceding , and his strategy was to transform the Constitution to explicitly protect slavery forever . <hl> Specifically , Crittenden proposed an amendment that would restore the 36 ° 30 ′ line from the Missouri Compromise and extend it all the way to the Pacific Ocean , protecting and ensuring slavery south of the line while prohibiting it north of the line ( Figure 15.3 ) . <hl> <hl> He further proposed an amendment that would prohibit Congress from abolishing slavery anywhere it already existed or from interfering with the interstate slave trade . <hl>", "hl_sentences": "The Confederacy also gained the backing of the Five Civilized Tribes , as they were called , in the Indian Territory . Specifically , Crittenden proposed an amendment that would restore the 36 ° 30 ′ line from the Missouri Compromise and extend it all the way to the Pacific Ocean , protecting and ensuring slavery south of the line while prohibiting it north of the line ( Figure 15.3 ) . He further proposed an amendment that would prohibit Congress from abolishing slavery anywhere it already existed or from interfering with the interstate slave trade .", "question": { "cloze_format": "It was not a provision of the Crittenden Compromise ___.", "normal_format": "Which was not a provision of the Crittenden Compromise?", "question_choices": [ "that the Five Civilized Tribes would be admitted into the Confederacy", "that the 36°30′ line from the Missouri Compromise would be restored and extended", "that Congress would be prohibited from abolishing slavery where it already existed", "that the interstate slave trade would be allowed to continue" ], "question_id": "fs-idp27020016", "question_text": "Which was not a provision of the Crittenden Compromise?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 3, "ans_text": "the ability to fight defensively, rather than offensively" }, "bloom": null, "hl_context": "<hl> The Union side held many advantages as well . <hl> <hl> Its larger population , bolstered by continued immigration from Europe throughout the 1860s , gave it greater manpower reserves to draw upon . <hl> <hl> The North ’ s greater industrial capabilities and extensive railroad grid made it far better able to mobilize men and supplies for the war effort . <hl> <hl> The Industrial Revolution and the transportation revolution , beginning in the 1820s and continuing over the next several decades , had transformed the North . <hl> Throughout the war , the North was able to produce more war materials and move goods more quickly than the South . Furthermore , the farms of New England , the Mid-Atlantic , the Old Northwest , and the prairie states supplied Northern civilians and Union troops with abundant food throughout the war . Food shortages and hungry civilians were common in the South , where the best land was devoted to raising cotton , but not in the North .", "hl_sentences": "The Union side held many advantages as well . Its larger population , bolstered by continued immigration from Europe throughout the 1860s , gave it greater manpower reserves to draw upon . The North ’ s greater industrial capabilities and extensive railroad grid made it far better able to mobilize men and supplies for the war effort . The Industrial Revolution and the transportation revolution , beginning in the 1820s and continuing over the next several decades , had transformed the North .", "question": { "cloze_format": "All the following were strengths of the Union except ________.", "normal_format": "Which of the following was not a strength of the Union?", "question_choices": [ "a large population", "substantial industry", "an extensive railroad", "the ability to fight defensively, rather than offensively" ], "question_id": "fs-idp121046624", "question_text": "All the following were strengths of the Union except ________." }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 3, "ans_text": "D" }, "bloom": null, "hl_context": "<hl> Unlike the South , however , which could hunker down to defend itself and needed to maintain relatively short supply lines , the North had to go forth and conquer . <hl> Union armies had to establish long supply lines , and Union soldiers had to fight on unfamiliar ground and contend with a hostile civilian population off the battlefield . Furthermore , to restore the Union — Lincoln ’ s overriding goal , in 1861 — the United States , after defeating the Southern forces , would then need to pacify a conquered Confederacy , an area of over half a million square miles with nearly nine million residents . In short , although it had better resources and a larger population , the Union faced a daunting task against the well-positioned Confederacy . <hl> The Confederates had the advantage of being able to wage a defensive war , rather than an offensive one . <hl> They had to protect and preserve their new boundaries , but they did not have to be the aggressors against the Union . <hl> The war would be fought primarily in the South , which gave the Confederates the advantages of the knowledge of the terrain and the support of the civilian population . <hl> Further , the vast coastline from Texas to Virginia offered ample opportunities to evade the Union blockade . <hl> And with the addition of the Upper South states , especially Virginia , North Carolina , Tennessee , and Arkansas , the Confederacy gained a much larger share of natural resources and industrial might than the Deep South states could muster . <hl>", "hl_sentences": "Unlike the South , however , which could hunker down to defend itself and needed to maintain relatively short supply lines , the North had to go forth and conquer . The Confederates had the advantage of being able to wage a defensive war , rather than an offensive one . The war would be fought primarily in the South , which gave the Confederates the advantages of the knowledge of the terrain and the support of the civilian population . And with the addition of the Upper South states , especially Virginia , North Carolina , Tennessee , and Arkansas , the Confederacy gained a much larger share of natural resources and industrial might than the Deep South states could muster .", "question": { "cloze_format": "All the following were strengths of the Confederacy except ________.", "normal_format": "Which of the following was not a strength of the Confederacy?", "question_choices": [ "the ability to wage a defensive war", "shorter supply lines", "the resources of the Upper South states", "a strong navy" ], "question_id": "fs-idm80927376", "question_text": "All the following were strengths of the Confederacy except ________." }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 1, "ans_text": "B" }, "bloom": null, "hl_context": "In keeping with their longstanding objective of keeping slavery out of the newly settled western territories , the Republicans in Congress ( the dominant party ) passed several measures in 1862 . <hl> First , the Homestead Act provided generous inducements for Northerners to relocate and farm in the West . <hl> Settlers could lay claim to 160 acres of federal land by residing on the property for five years and improving it . The act not only motivated free-labor farmers to move west , but it also aimed to increase agricultural output for the war effort . The federal government also turned its attention to creating a transcontinental railroad to facilitate the movement of people and goods across the country . Congress chartered two companies , the Union Pacific and the Central Pacific , and provided generous funds for these two businesses to connect the country by rail . One of the reasons that the Confederacy was so economically devastated was its ill-advised gamble that cotton sales would continue during the war . The government had high hopes that Great Britain and France , which both used cotton as the raw material in their textile mills , would ensure the South ’ s economic strength — and therefore victory in the war — by continuing to buy . Furthermore , the Confederate government hoped that Great Britain and France would make loans to their new nation in order to ensure the continued flow of raw materials . <hl> These hopes were never realized . <hl> <hl> Great Britain in particular did not wish to risk war with the United States , which would have meant the invasion of Canada . <hl> The United States was also a major source of grain for Britain and an important purchaser of British goods . Furthermore , the blockade made Southern trade with Europe difficult . <hl> Instead , Great Britain , the major consumer of American cotton , found alternate sources in India and Egypt , leaving the South without the income or alliance it had anticipated . <hl> The war efforts were costing the new nation dearly . Nevertheless , the Confederate Congress heeded the pleas of wealthy plantation owners and refused to place a tax on enslaved people or cotton , despite the Confederacy ’ s desperate need for the revenue that such a tax would have raised . Instead , the Confederacy drafted a taxation plan that kept the Southern elite happy but in no way met the needs of the war . <hl> The government also resorted to printing immense amounts of paper money , which quickly led to runaway inflation . <hl> Food prices soared , and poor , White Southerners faced starvation . In April 1863 , thousands of hungry people rioted in Richmond , Virginia ( Figure 15.10 ) . Many of the rioters were mothers who could not feed their children . The riot ended when President Davis threatened to have Confederate forces open fire on the crowds . The Confederate government in Richmond , Virginia , exercised sweeping powers to ensure victory , in stark contradiction to the states ’ rights sentiments held by many Southern leaders . <hl> The initial emotional outburst of enthusiasm for war in the Confederacy waned , and the Confederate government instituted a military draft in April 1862 . <hl> Under the terms of the draft , all men between the ages of eighteen and thirty-five would serve three years . The draft had a different effect on men of different socioeconomic classes . One loophole permitted men to hire substitutes instead of serving in the Confederate army . This provision favored the wealthy over the poor , and led to much resentment and resistance . Exercising its power over the states , the Confederate Congress denied state efforts to circumvent the draft .", "hl_sentences": "First , the Homestead Act provided generous inducements for Northerners to relocate and farm in the West . These hopes were never realized . Great Britain in particular did not wish to risk war with the United States , which would have meant the invasion of Canada . Instead , Great Britain , the major consumer of American cotton , found alternate sources in India and Egypt , leaving the South without the income or alliance it had anticipated . The government also resorted to printing immense amounts of paper money , which quickly led to runaway inflation . The initial emotional outburst of enthusiasm for war in the Confederacy waned , and the Confederate government instituted a military draft in April 1862 .", "question": { "cloze_format": "The North did not ___ to mobilize for war.", "normal_format": "Which of the following did the North not do to mobilize for war?", "question_choices": [ "institute a military draft", "form a military alliance with Great Britain", "print paper money", "pass the Homestead Act" ], "question_id": "fs-idp25495200", "question_text": "Which of the following did the North not do to mobilize for war?" }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 2, "ans_text": "C" }, "bloom": null, "hl_context": "Northern Democrats railed against Lincoln and the war . Republicans labeled these vocal opponents of the President Copperheads , a term that many antiwar Democrats accepted . As the anti-Lincoln poster below illustrates , his enemies tried to paint him as an untrustworthy and suspect leader ( Figure 15.18 ) . <hl> It seemed to most in the North that the Democratic candidate , General George B . McClellan , who did not support abolition and was replaced with another commander by Lincoln , would win the election . <hl> <hl> Despite the military successes for the Union army in 1863 , in 1864 , Lincoln ’ s status among many Northern voters plummeted . <hl> <hl> Citing the suspension of the writ of habeas corpus , many saw him as a dictator , bent on grabbing power while senselessly and uncaringly drafting more young men into combat . <hl> <hl> Arguably , his greatest liability , however , was the Emancipation Proclamation and the enlistment of African American soldiers . <hl> Many Whites in the North found this deeply offensive , since they still believed in racial inequality . The 1863 New York City Draft Riots illustrated the depth of White anger .", "hl_sentences": "It seemed to most in the North that the Democratic candidate , General George B . McClellan , who did not support abolition and was replaced with another commander by Lincoln , would win the election . Despite the military successes for the Union army in 1863 , in 1864 , Lincoln ’ s status among many Northern voters plummeted . Citing the suspension of the writ of habeas corpus , many saw him as a dictator , bent on grabbing power while senselessly and uncaringly drafting more young men into combat . Arguably , his greatest liability , however , was the Emancipation Proclamation and the enlistment of African American soldiers .", "question": { "cloze_format": "Many peaple did not oppose Lincoln's reelection in 1864 because ___.", "normal_format": "Which of the following is not a reason why many people opposed Lincoln’s reelection in 1864?", "question_choices": [ "He appeared to have overstepped his authority by suspending the writ of habeas corpus.", "He issued the Emancipation Proclamation.", "He had replaced General George B. McClellan.", "He was seen as a power-hungry dictator." ], "question_id": "fs-idp210630432", "question_text": "Which of the following is not a reason why many people opposed Lincoln’s reelection in 1864?" }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 0, "ans_text": "to destroy military and civilian resources wherever possible" }, "bloom": null, "hl_context": "The other major Union campaigns of 1864 were more successful and gave President Lincoln the advantage that he needed to win reelection in November . In August 1864 , the Union navy captured Mobile Bay . <hl> General Sherman invaded the Deep South , advancing slowly from Tennessee into Georgia , confronted at every turn by the Confederates , who were commanded by Johnston . <hl> When President Davis replaced Johnston with General John B . Hood , the Confederates made a daring but ultimately costly direct attack on the Union army that failed to drive out the invaders . Atlanta fell to Union forces on September 2 , 1864 . The fall of Atlanta held tremendous significance for the war-weary Union and helped to reverse the North ’ s sinking morale . In keeping with the logic of total war , Sherman ’ s forces cut a swath of destruction to Savannah . <hl> On Sherman ’ s March to the Sea , the Union army , seeking to demoralize the South , destroyed everything in its path , despite strict instructions regarding the preservation of civilian property . <hl> Although towns were left standing , houses and barns were burned . Homes were looted , food was stolen , crops were destroyed , orchards were burned , and livestock was killed or confiscated . Savannah fell on December 21 , 1864 — a Christmas gift for Lincoln , Sherman proclaimed . In 1865 , Sherman ’ s forces invaded South Carolina , capturing Charleston and Columbia . In Columbia , the state capital , the Union army burned slaveholders ’ homes and destroyed much of the city . From South Carolina , Sherman ’ s force moved north in an effort to join Grant and destroy Lee ’ s army .", "hl_sentences": "General Sherman invaded the Deep South , advancing slowly from Tennessee into Georgia , confronted at every turn by the Confederates , who were commanded by Johnston . On Sherman ’ s March to the Sea , the Union army , seeking to demoralize the South , destroyed everything in its path , despite strict instructions regarding the preservation of civilian property .", "question": { "cloze_format": "General Sherman's objective on his March to the Sea was ____.", "normal_format": "What was General Sherman’s objective on his March to the Sea?", "question_choices": [ "to destroy military and civilian resources wherever possible", "to free Black prisoners of war", "to join his army to that of General Grant", "to capture General Robert E. Lee" ], "question_id": "fs-idp151921552", "question_text": "What was General Sherman’s objective on his March to the Sea?" }, "references_are_paraphrase": null } ]
15
15.1 The Origins and Outbreak of the Civil War Learning Objectives By the end of this section, you will be able to: Explain the major events that occurred during the Secession Crisis Describe the creation and founding principles of the Confederate States of America The 1860 election of Abraham Lincoln was a turning point for the United States. Throughout the tumultuous 1850s, the Fire-Eaters of the southern states had been threatening to leave the Union. With Lincoln’s election, they prepared to make good on their threats. Indeed, the Republican president-elect appeared to be their worst nightmare. The Republican Party committed itself to keeping slavery out of the territories as the country expanded westward, a position that shocked southern sensibilities. Meanwhile, southern leaders suspected that Republican abolitionists would employ the violent tactics of John Brown to deprive southerners of their enslaved property. The threat posed by the Republican victory in the election of 1860 spurred eleven southern states to leave the Union to form the Confederate States of America, a new republic dedicated to maintaining and expanding slavery. The Union, led by President Lincoln, was unwilling to accept the departure of these states and committed itself to restoring the country. Beginning in 1861 and continuing until 1865, the United States engaged in a brutal Civil War that claimed the lives of over 600,000 soldiers. By 1863, the conflict had become not only a war to save the Union, but also a war to end slavery in the United States. Only after four years of fighting did the North prevail. The Union was preserved, and the institution of slavery had been destroyed in the nation. THE CAUSES OF THE CIVIL WAR Lincoln’s election sparked the southern secession fever into flame, but it did not cause the Civil War. For decades before Lincoln took office, the sectional divisions in the country had been widening. Both the Northern and southern states engaged in inflammatory rhetoric and agitation, and violent emotions ran strong on both sides. Several factors played into the ultimate split between the North and the South. One key irritant was the question of slavery’s expansion westward. The debate over whether new states would be slave or free reached back to the controversy over statehood for Missouri beginning in 1819 and Texas in the 1830s and early 1840s. This question arose again after the Mexican-American War (1846–1848), when the government debated whether slavery would be permitted in the territories taken from Mexico. Efforts in Congress to reach a compromise in 1850 fell back on the principle of popular sovereignty—letting the people in the new territories south of the 1820 Missouri Compromise line decide whether to allow slavery. This same principle came to be applied to the Kansas-Nebraska territories in 1854, a move that added fuel to the fire of sectional conflict by destroying the Missouri Compromise boundary and leading to the birth of the Republican Party. In the end, popular sovereignty proved to be no solution at all. This was especially true in “Bleeding Kansas” in the mid-1850s, as pro- and antislavery forces battled each another in an effort to gain the upper hand. The small but very vocal abolitionist movement further contributed to the escalating tensions between the North and the South. Since the 1830s, abolitionists, led by journalist and reformer William Lloyd Garrison, had cast slavery as a national sin and called for its immediate end. For three decades, the abolitionists—a minority even within the antislavery movement—had had a significant effect on American society by bringing the evils of slavery into the public consciousness. By the 1850s, some of the most radical abolitionists, such as John Brown, had resorted to violence in their efforts to destroy the institution of slavery. The formation of the Liberty Party (1840), the Free-Soil Party (1848), and the Republican Party (1854), all of which strongly opposed the spread of slavery to the West, brought the question solidly into the political arena. Although not all those who opposed the westward expansion of slavery had a strong abolitionist bent, the attempt to limit slaveholders’ control of their human property stiffened the resolve of southern leaders to defend their society at all costs. Prohibiting slavery’s expansion, they argued, ran counter to fundamental American property rights. Across the country, people of all political stripes worried that the nation’s arguments would cause irreparable rifts in the country. Despite the ruptures and tensions, by the 1860s, some hope of healing the nation still existed. Before Lincoln took office, John Crittenden, a senator from Kentucky who had helped form the Constitutional Union Party during the 1860 presidential election, attempted to defuse the explosive situation by offering six constitutional amendments and a series of resolutions, known as the Crittenden Compromise . Crittenden’s goal was to keep the South from seceding, and his strategy was to transform the Constitution to explicitly protect slavery forever. Specifically, Crittenden proposed an amendment that would restore the 36°30′ line from the Missouri Compromise and extend it all the way to the Pacific Ocean, protecting and ensuring slavery south of the line while prohibiting it north of the line ( Figure 15.3 ). He further proposed an amendment that would prohibit Congress from abolishing slavery anywhere it already existed or from interfering with the interstate slave trade. Republicans, including President-elect Lincoln, rejected Crittenden’s proposals because they ran counter to the party’s goal of keeping slavery out of the territories. The southern states also rejected Crittenden’s attempts at compromise, because it would prevent slaveholders from taking their human chattel north of the 36°30′ line. On December 20, 1860, only a few days after Crittenden’s proposal was introduced in Congress, South Carolina began the march towards war when it seceded from the United States. Three more states of the Deep South—Mississippi, Florida, and Alabama—seceded before the U.S. Senate rejected Crittenden’s proposal on January 16, 1861. Georgia, Louisiana, and Texas joined them in rapid succession on January 19, January 26, and February 1, respectively ( Figure 15.4 ). In many cases, these secessions occurred after extremely divided conventions and popular votes. A lack of unanimity prevailed in much of the South. THE CREATION OF THE CONFEDERATE STATES OF AMERICA The seven Deep South states that seceded quickly formed a new government. In the opinion of many Southern politicians, the federal Constitution that united the states as one nation was a contract by which individual states had agreed to be bound. However, they maintained, the states had not sacrificed their autonomy and could withdraw their consent to be controlled by the federal government. In their eyes, their actions were in keeping with the nature of the Constitution and the social contract theory of government that had influenced the founders of the American Republic. The new nation formed by these men would not be a federal union, but a confederation. In a confederation, individual member states agree to unite under a central government for some purposes, such as defense, but to retain autonomy in other areas of government. In this way, states could protect themselves, and slavery, from interference by what they perceived to be an overbearing central government. The constitution of the Confederate States of America (CSA), or the Confederacy , drafted at a convention in Montgomery, Alabama, in February 1861, closely followed the 1787 Constitution. The only real difference between the two documents centered on slavery. The Confederate Constitution declared that the new nation existed to defend and perpetuate racial slavery, and the leadership of the slaveholding class. Specifically, the constitution protected the interstate slave trade, guaranteed that slavery would exist in any new territory gained by the Confederacy, and, perhaps most importantly, in Article One, Section Nine, declared that “No . . . law impairing or denying the right of property in negro slaves shall be passed.” Beyond its focus on slavery, the Confederate Constitution resembled the 1787 U.S. Constitution. It allowed for a Congress composed of two chambers, a judicial branch, and an executive branch with a president to serve for six years. The convention delegates chose Jefferson Davis of Mississippi to lead the new provisional government as president and Alexander Stephens of Georgia to serve as vice president until elections could be held in the spring and fall of 1861. By that time, four new states—Virginia, Arkansas, Tennessee, and North Carolina—had joined the CSA. As 1861 progressed, the Confederacy claimed Missouri and Kentucky, even though no ordinance of secession had been approved in those states. Southern nationalism ran high, and the Confederacy, buoyed by its sense of purpose, hoped that their new nation would achieve eminence in the world. By the time Lincoln reached Washington, DC, in February 1861, the CSA had already been established. The new president confronted an unprecedented crisis. A conference held that month with delegates from the Southern states failed to secure a promise of peace or to restore the Union. On inauguration day, March 4, 1861, the new president repeated his views on slavery: “I have no purpose, directly or indirectly, to interfere with the institution of slavery in the States where it exists. I believe I have no lawful right to do so, and I have no inclination to do so.” His recognition of slavery in the South did nothing to mollify slaveholders, however, because Lincoln also pledged to keep slavery from expanding into the new western territories. Furthermore, in his inaugural address, Lincoln made clear his commitment to maintaining federal power against the secessionists working to destroy it. Lincoln declared that the Union could not be dissolved by individual state actions, and, therefore, secession was unconstitutional. FORT SUMTER President Lincoln made it clear to Southern secessionists that he would fight to maintain federal property and to keep the Union intact. Other politicians, however, still hoped to avoid the use of force to resolve the crisis. In February 1861, in an effort to entice the rebellious states to return to the Union without resorting to force, Thomas Corwin, a representative from Ohio, introduced a proposal to amend the Constitution in the House of Representatives. His was but one of several measures proposed in January and February 1861, to head off the impending conflict and save the United States. The proposed amendment would have made it impossible for Congress to pass any law abolishing slavery. The proposal passed the House on February 28, 1861, and the Senate passed the proposal on March 2, 1861. It was then sent to the states to be ratified. Once ratified by three-quarters of state legislatures, it would become law. In his inaugural address, Lincoln stated that he had no objection to the amendment, and his predecessor James Buchanan had supported it. By the time of Lincoln’s inauguration, however, seven states had already left the Union. Of the remaining states, Ohio ratified the amendment in 1861, and Maryland and Illinois did so in 1862. Despite this effort at reconciliation, the Confederate states did not return to the Union. Indeed, by the time of the Corwin amendment’s passage through Congress, Confederate forces in the Deep South had already begun to take over federal forts. The loss of Fort Sumter , in the harbor of Charleston, South Carolina, proved to be the flashpoint in the contest between the new Confederacy and the federal government. A small Union garrison of fewer than one hundred soldiers and officers held the fort, making it a vulnerable target for the Confederacy. Fire-Eaters pressured Jefferson Davis to take Fort Sumter and thereby demonstrate the Confederate government’s resolve. Some also hoped that the Confederacy would gain foreign recognition, especially from Great Britain, by taking the fort in the South’s most important Atlantic port. The situation grew dire as local merchants refused to sell food to the fort’s Union soldiers, and by mid-April, the garrison’s supplies began to run out. President Lincoln let it be known to Confederate leaders that he planned to resupply the Union forces. His strategy was clear: The decision to start the war would rest squarely on the Confederates, not on the Union. On April 12, 1861, Confederate forces in Charleston began a bombardment of Fort Sumter ( Figure 15.5 ). Two days later, the Union soldiers there surrendered. The attack on Fort Sumter meant war had come, and on April 15, 1861, Lincoln called upon loyal states to supply armed forces to defeat the rebellion and regain Fort Sumter. Faced with the need to choose between the Confederacy and the Union, border states and those of the Upper South, which earlier had been reluctant to dissolve their ties with the United States, were inspired to take action. They quickly voted for secession. A convention in Virginia that had been assembled earlier to consider the question of secession voted to join the Confederacy on April 17, two days after Lincoln called for troops. Arkansas left the Union on May 6 along with Tennessee one day later. North Carolina followed on May 20. Not all residents of the border states and the Upper South wished to join the Confederacy, however. Pro-Union feelings remained strong in Tennessee, especially in the eastern part of the state where the enslaved population was small and consisted largely of house servants owned by the wealthy. The state of Virginia—home of revolutionary leaders and presidents such as George Washington, Thomas Jefferson, James Madison, and James Monroe—literally was split on the issue of secession. Residents in the north and west of the state, where few slaveholders resided, rejected secession. These counties subsequently united to form “West Virginia,” which entered the Union as a free state in 1863. The rest of Virginia, including the historic lands along the Chesapeake Bay that were home to such early American settlements as Jamestown and Williamsburg, joined the Confederacy. The addition of this area gave the Confederacy even greater hope and brought General Robert E. Lee, arguably the best military commander of the day, to their side. In addition, the secession of Virginia brought Washington, DC, perilously close to the Confederacy, and fears that the border state of Maryland would also join the CSA, thus trapping the U.S. capital within Confederate territories, plagued Lincoln. The Confederacy also gained the backing of the Five Civilized Tribes, as they were called, in the Indian Territory. The Five Civilized Tribes comprised the Choctaws, Chickasaws, Creeks, Seminoles, and Cherokees. The tribes supported slavery and many members were enslavers. These Native American slaveholders, who had been forced from their lands in Georgia and elsewhere in the Deep South during the presidency of Andrew Jackson, now found unprecedented common cause with White slaveholders. The CSA even allowed them to send delegates to the Confederate Congress. While most slaveholding states joined the Confederacy, four crucial slave states remained in the Union ( Figure 15.6 ). Delaware, which was technically a slave state despite its tiny enslaved population, never voted to secede. Maryland, despite deep divisions, remained in the Union as well. Missouri became the site of vicious fighting and the home of pro-Confederate guerillas but never joined the Confederacy. Kentucky declared itself neutral, although that did little to stop the fighting that occurred within the state. In all, these four states deprived the Confederacy of key resources and soldiers. 15.2 Early Mobilization and War Learning Objectives By the end of this section, you will be able to: Assess the strengths and weaknesses of the Confederacy and the Union Explain the strategic importance of the Battle of Bull Run and the Battle of Shiloh In 1861, enthusiasm for war ran high on both sides. The North fought to restore the Union, which Lincoln declared could never be broken. The Confederacy, which by the summer of 1861 consisted of eleven states, fought for its independence from the United States. The continuation of slavery was a central issue in the war, of course, although abolitionism and western expansion also played roles, and Northerners and Southerners alike flocked eagerly to the conflict. Both sides thought it would be over quickly. Militarily, however, the North and South were more equally matched than Lincoln had realized, and it soon became clear that the war effort would be neither brief nor painless. In 1861, Americans in both the North and South romanticized war as noble and positive. Soon the carnage and slaughter would awaken them to the horrors of war. THE FIRST BATTLE OF BULL RUN After the fall of Fort Sumter on April 15, 1861, Lincoln called for seventy-five thousand volunteers from state militias to join federal forces. His goal was a ninety-day campaign to put down the Southern rebellion. The response from state militias was overwhelming, and the number of Northern troops exceeded the requisition. Also in April, Lincoln put in place a naval blockade of the South, a move that gave tacit recognition of the Confederacy while providing a legal excuse for the British and the French to trade with Southerners. The Confederacy responded to the blockade by declaring that a state of war existed with the United States. This official pronouncement confirmed the beginning of the Civil War. Men rushed to enlist, and the Confederacy turned away tens of thousands who hoped to defend the new nation. Many believed that a single, heroic battle would decide the contest. Some questioned how committed Southerners really were to their cause. Northerners hoped that most Southerners would not actually fire on the American flag. Meanwhile, Lincoln and military leaders in the North hoped a quick blow to the South, especially if they could capture the Confederacy’s new capital of Richmond, Virginia, would end the rebellion before it went any further. On July 21, 1861, the two armies met near Manassas, Virginia, along Bull Run Creek , only thirty miles from Washington, DC. So great was the belief that this would be a climactic Union victory that many Washington socialites and politicians brought picnic lunches to a nearby area, hoping to witness history unfolding before them. At the First Battle of Bull Run, also known as First Manassas, some sixty thousand troops assembled, most of whom had never seen combat, and each side sent eighteen thousand into the fray. The Union forces attacked first, only to be pushed back. The Confederate forces then carried the day, sending the Union soldiers and Washington, DC, onlookers scrambling back from Virginia and destroying Union hopes of a quick, decisive victory. Instead, the war would drag on for four long, deadly years ( Figure 15.7 ). BALANCE SHEET: THE UNION AND THE CONFEDERACY As it became clearer that the Union would not be dealing with an easily quashed rebellion, the two sides assessed their strengths and weaknesses. At the onset on the war, in 1861 and 1862, they stood as relatively equal combatants. The Confederates had the advantage of being able to wage a defensive war, rather than an offensive one. They had to protect and preserve their new boundaries, but they did not have to be the aggressors against the Union. The war would be fought primarily in the South, which gave the Confederates the advantages of the knowledge of the terrain and the support of the civilian population. Further, the vast coastline from Texas to Virginia offered ample opportunities to evade the Union blockade. And with the addition of the Upper South states, especially Virginia, North Carolina, Tennessee, and Arkansas, the Confederacy gained a much larger share of natural resources and industrial might than the Deep South states could muster. Still, the Confederacy had disadvantages. The South’s economy depended heavily on the export of cotton, but with the naval blockade, the flow of cotton to England, the region’s primary importer, came to an end. The blockade also made it difficult to import manufactured goods. Although the secession of the Upper South added some industrial assets to the Confederacy, overall, the South lacked substantive industry or an extensive railroad infrastructure to move men and supplies. To deal with the lack of commerce and the resulting lack of funds, the Confederate government began printing paper money, leading to runaway inflation ( Figure 15.8 ). The advantage that came from fighting on home territory quickly turned to a disadvantage when Confederate armies were defeated and Union forces destroyed Southern farms and towns, and forced Southern civilians to take to the road as refugees. Finally, the population of the South stood at fewer than nine million people, of whom nearly four million were enslaved Black people, compared to over twenty million residents in the North. These limited numbers became a major factor as the war dragged on and the death toll rose. The Union side held many advantages as well. Its larger population, bolstered by continued immigration from Europe throughout the 1860s, gave it greater manpower reserves to draw upon. The North’s greater industrial capabilities and extensive railroad grid made it far better able to mobilize men and supplies for the war effort. The Industrial Revolution and the transportation revolution, beginning in the 1820s and continuing over the next several decades, had transformed the North. Throughout the war, the North was able to produce more war materials and move goods more quickly than the South. Furthermore, the farms of New England, the Mid-Atlantic, the Old Northwest, and the prairie states supplied Northern civilians and Union troops with abundant food throughout the war. Food shortages and hungry civilians were common in the South, where the best land was devoted to raising cotton, but not in the North. Unlike the South, however, which could hunker down to defend itself and needed to maintain relatively short supply lines, the North had to go forth and conquer. Union armies had to establish long supply lines, and Union soldiers had to fight on unfamiliar ground and contend with a hostile civilian population off the battlefield. Furthermore, to restore the Union—Lincoln’s overriding goal, in 1861—the United States, after defeating the Southern forces, would then need to pacify a conquered Confederacy, an area of over half a million square miles with nearly nine million residents. In short, although it had better resources and a larger population, the Union faced a daunting task against the well-positioned Confederacy. MILITARY STALEMATE The military forces of the Confederacy and the Union battled in 1861 and early 1862 without either side gaining the upper hand. The majority of military leaders on both sides had received the same military education and often knew one another personally, either from their time as students at West Point or as commanding officers in the Mexican-American War. This familiarity allowed them to anticipate each other’s strategies. Both sides believed in the use of concentrated armies charged with taking the capital city of the enemy. For the Union, this meant the capture of the Confederate capital in Richmond, Virginia, whereas Washington, DC, stood as the prize for Confederate forces. After hopes of a quick victory faded at Bull Run, the months dragged on without any major movement on either side ( Figure 15.9 ). General George B. McClellan, the general in chief of the army, responsible for overall control of Union land forces, proved especially reluctant to engage in battle with the Confederates. In direct command of the Army of the Potomac , the Union fighting force operating outside Washington, DC, McClellan believed, incorrectly, that Confederate forces were too strong to defeat and was reluctant to risk his troops in battle. His cautious nature made him popular with his men but not with the president or Congress. By 1862, however, both President Lincoln and the new Secretary of War Edwin Stanton had tired of waiting. The Union put forward a new effort to bolster troop strength, enlisting one million men to serve for three-year stints in the Army of the Potomac. In January 1862, Lincoln and Stanton ordered McClellan to invade the Confederacy with the goal of capturing Richmond. To that end, General McClellan slowly moved 100,000 soldiers of the Army of the Potomac toward Richmond but stopped a few miles outside the city. As he did so, a Confederate force led by Thomas “Stonewall” Jackson moved north to take Washington, DC. To fend off Jackson’s attack, somewhere between one-quarter and one-third of McClellan’s soldiers, led by Major General Irvin McDowell, returned to defend the nation’s capital, a move that Jackson hoped would leave the remaining troops near Richmond more vulnerable. Having succeeding in drawing off a sizable portion of the Union force, he joined General Lee to launch an attack on McClellan’s remaining soldiers near Richmond. From June 25 to July 1, 1862, the two sides engaged in the brutal Seven Days Battles that killed or wounded almost twenty thousand Confederate and ten thousand Union soldiers. McClellan’s army finally returned north, having failed to take Richmond. General Lee, flush from his success at keeping McClellan out of Richmond, tried to capitalize on the Union’s failure by taking the fighting northward. He moved his forces into northern Virginia, where, at the Second Battle of Bull Run, the Confederates again defeated the Union forces. Lee then pressed into Maryland, where his troops met the much larger Union forces near Sharpsburg, at Antietam Creek. The ensuing one-day battle on September 17, 1862, led to a tremendous loss of life. Although there are varying opinions about the total number of deaths, eight thousand soldiers were killed or wounded, more than on any other single day of combat. Once again, McClellan, mistakenly believing that the Confederate troops outnumbered his own, held back a significant portion of his forces. Lee withdrew from the field first, but McClellan, fearing he was outnumbered, refused to pursue him. The Union army’s inability to destroy Lee’s army at Antietam made it clear to Lincoln that McClellan would never win the war, and the president was forced to seek a replacement. Lincoln wanted someone who could deliver a decisive Union victory. He also personally disliked McClellan, who referred to the president as a “baboon” and a “gorilla,” and constantly criticized his decisions. Lincoln chose General Ambrose E. Burnside to replace McClellan as commander of the Army of the Potomac, but Burnside’s efforts to push into Virginia failed in December 1862, as Confederates held their position at Fredericksburg and devastated Burnside’s forces with heavy artillery fire. The Union’s defeat at Fredericksburg harmed morale in the North but bolstered Confederate spirits. By the end of 1862, the Confederates were still holding their ground in Virginia. Burnside’s failure led Lincoln to make another change in leadership, and Joseph “Fighting Joe” Hooker took over command of the Army of the Potomac in January 1863. General Ulysses S. Grant’s Army of the West , operating in Kentucky, Tennessee, and the Mississippi River Valley, had been more successful. In the western campaign, the goal of both the Union and the Confederacy was to gain control of the major rivers in the west, especially the Mississippi. If the Union could control the Mississippi, the Confederacy would be split in two. The fighting in this campaign initially centered in Tennessee, where Union forces commanded by Grant pushed Confederate troops back and gained control of the state. The major battle in the western theater took place at Pittsburgh Landing, Tennessee, on April 6 and 7, 1862. Grant’s army was camped on the west side of the Tennessee River near a small log church called Shiloh, which gave the battle its name. On Sunday morning, April 6, Confederate forces under General Albert Sidney Johnston attacked Grant’s encampment with the goal of separating them from their supply line on the Tennessee River and driving them into the swamps on the river’s western side, where they could be destroyed. Union general William Tecumseh Sherman tried to rally the Union forces as Grant, who had been convalescing from an injured leg when the attack began and was unable to walk without crutches, called for reinforcements and tried to mount a defense. Many of Union troops fled in terror. Unfortunately for the Confederates, Johnston was killed on the afternoon of the first day. Leadership of the Southern forces fell to General P. G. T. Beauregard, who ordered an assault at the end of that day. This assault was so desperate that one of the two attacking columns did not even have ammunition. Heavily reinforced Union forces counterattacked the next day, and the Confederate forces were routed. Grant had maintained the Union foothold in the western part of the Confederacy. The North could now concentrate on its efforts to gain control of the Mississippi River, splitting the Confederacy in two and depriving it of its most important water route. In the spring and summer of 1862, the Union was successful in gaining control of part of the Mississippi River. In April 1862, the Union navy under Admiral David Farragut fought its way past the forts that guarded New Orleans and fired naval guns upon the below-sea-level city. When it became obvious that New Orleans could no longer be defended, Confederate major general Marshall Lovell sent his artillery upriver to Vicksburg, Mississippi. Armed civilians in New Orleans fought the Union forces that entered the city. They also destroyed ships and military supplies that might be used by the Union. Upriver, Union naval forces also bombarded Fort Pillow, forty miles from Memphis, Tennessee, a Southern industrial center and one of the largest cities in the Confederacy. On June 4, 1862, the Confederate defenders abandoned the fort. On June 6, Memphis fell to the Union after the ships defending it were destroyed. 15.3 1863: The Changing Nature of the War Learning Objectives By the end of this section, you will be able to: Explain what is meant by the term “total war” and provide examples Describe mobilization efforts in the North and the South Explain why 1863 was a pivotal year in the war Wars have their own logic; they last far longer than anyone anticipates at the beginning of hostilities. As they drag on, the energy and zeal that marked the entry into warfare often wane, as losses increase and people on both sides suffer the tolls of war. The American Civil War is a case study of this characteristic of modern war. Although Northerners and Southerners both anticipated that the battle between the Confederacy and the Union would be settled quickly, it soon became clear to all that there was no resolution in sight. The longer the war continued, the more it began to affect life in both the North and the South. Increased need for manpower, the issue of slavery, and the ongoing challenges of keeping the war effort going changed the way life on both sides as the conflict progressed. MASS MOBILIZATION By late 1862, the course of the war had changed to take on the characteristics of total war , in which armies attempt to demoralize the enemy by both striking military targets and disrupting their opponent’s ability to wage war through destruction of their resources. In this type of war, armies often make no distinction between civilian and military targets. Both the Union and Confederate forces moved toward total war, although neither side ever entirely abolished the distinction between military and civilian. Total war also requires governments to mobilize all resources, extending their reach into their citizens’ lives as never before. Another reality of war that became apparent in 1862 and beyond was the influence of combat on the size and scope of government. Both the Confederacy and the Union governments had to continue to grow in order to manage the logistics of recruiting men and maintaining, feeding, and equipping an army. Confederate Mobilization The Confederate government in Richmond, Virginia, exercised sweeping powers to ensure victory, in stark contradiction to the states’ rights sentiments held by many Southern leaders. The initial emotional outburst of enthusiasm for war in the Confederacy waned, and the Confederate government instituted a military draft in April 1862. Under the terms of the draft, all men between the ages of eighteen and thirty-five would serve three years. The draft had a different effect on men of different socioeconomic classes. One loophole permitted men to hire substitutes instead of serving in the Confederate army. This provision favored the wealthy over the poor, and led to much resentment and resistance. Exercising its power over the states, the Confederate Congress denied state efforts to circumvent the draft. In order to fund the war, the Confederate government also took over the South’s economy. The government ran Southern industry and built substantial transportation and industrial infrastructure to make the weapons of war. Over the objections of slaveholders, it impressed enslaved people, seizing these enslaved workers from their owners and forcing them to work on fortifications and rail lines. Concerned about the resistance to and unhappiness with the government measures, in 1862, the Confederate Congress gave President Davis the power to suspend the writ of habeas corpus , the right of those arrested to be brought before a judge or court to determine whether there is cause to hold the prisoner. With a stated goal of bolstering national security in the fledgling republic, this change meant that the Confederacy could arrest and detain indefinitely any suspected enemy without giving a reason. This growth of the Confederate central government stood as a glaring contradiction to the earlier states’ rights argument of pro-Confederate advocates. The war efforts were costing the new nation dearly. Nevertheless, the Confederate Congress heeded the pleas of wealthy plantation owners and refused to place a tax on enslaved people or cotton, despite the Confederacy’s desperate need for the revenue that such a tax would have raised. Instead, the Confederacy drafted a taxation plan that kept the Southern elite happy but in no way met the needs of the war. The government also resorted to printing immense amounts of paper money, which quickly led to runaway inflation. Food prices soared, and poor, White Southerners faced starvation. In April 1863, thousands of hungry people rioted in Richmond, Virginia ( Figure 15.10 ). Many of the rioters were mothers who could not feed their children. The riot ended when President Davis threatened to have Confederate forces open fire on the crowds. One of the reasons that the Confederacy was so economically devastated was its ill-advised gamble that cotton sales would continue during the war. The government had high hopes that Great Britain and France, which both used cotton as the raw material in their textile mills, would ensure the South’s economic strength—and therefore victory in the war—by continuing to buy. Furthermore, the Confederate government hoped that Great Britain and France would make loans to their new nation in order to ensure the continued flow of raw materials. These hopes were never realized. Great Britain in particular did not wish to risk war with the United States, which would have meant the invasion of Canada. The United States was also a major source of grain for Britain and an important purchaser of British goods. Furthermore, the blockade made Southern trade with Europe difficult. Instead, Great Britain, the major consumer of American cotton, found alternate sources in India and Egypt, leaving the South without the income or alliance it had anticipated. Dissent within the Confederacy also affected the South’s ability to fight the war. Confederate politicians disagreed over the amount of power that the central government should be allowed to exercise. Many states’ rights advocates, who favored a weak central government and supported the sovereignty of individual states, resented President Davis’s efforts to conscript troops, impose taxation to pay for the war, and requisition necessary resources. Governors in the Confederate states often proved reluctant to provide supplies or troops for the use of the Confederate government. Even Jefferson Davis’s vice president Alexander Stephens opposed conscription, the seizure of enslaved property to work for the Confederacy, and suspension of habeas corpus. Class divisions also divided Confederates. Poor White people resented the ability of wealthy slaveholders to excuse themselves from military service. Racial tensions plagued the South as well. On those occasions when free Black people volunteered to serve in the Confederate army, they were turned away, and enslaved African Americans were regarded with fear and suspicion, as White people whispered among themselves about the possibility of insurrections by enslaved people. Union Mobilization Mobilization for war proved to be easier in the North than it was in the South. During the war, the federal government in Washington, DC, like its Southern counterpart, undertook a wide range of efforts to ensure its victory over the Confederacy. To fund the war effort and finance the expansion of Union infrastructure, Republicans in Congress drastically expanded government activism, impacting citizens’ everyday lives through measures such as new types of taxation. The government also contracted with major suppliers of food, weapons, and other needed materials. Virtually every sector of the Northern economy became linked to the war effort. In keeping with their longstanding objective of keeping slavery out of the newly settled western territories, the Republicans in Congress (the dominant party) passed several measures in 1862. First, the Homestead Act provided generous inducements for Northerners to relocate and farm in the West. Settlers could lay claim to 160 acres of federal land by residing on the property for five years and improving it. The act not only motivated free-labor farmers to move west, but it also aimed to increase agricultural output for the war effort. The federal government also turned its attention to creating a transcontinental railroad to facilitate the movement of people and goods across the country. Congress chartered two companies, the Union Pacific and the Central Pacific, and provided generous funds for these two businesses to connect the country by rail. The Republican emphasis on free labor, rather than enslaved labor, also influenced the 1862 Land Grant College Act, commonly known as the Morrill Act after its author, Vermont Republican senator Justin Smith Morrill. The measure provided for the creation of agricultural colleges, funded through federal grants, to teach the latest agricultural techniques. Each state in the Union would be granted thirty thousand acres of federal land for the use of these institutions of higher education. Congress paid for the war using several strategies. They levied a tax on the income of the wealthy, as well as a tax on all inheritances. They also put high tariffs in place. Finally, they passed two National Bank Acts, one in 1863 and one in 1864, calling on the U.S. Treasury to issue war bonds and on Union banks to buy the bonds. A Union campaign to convince individuals to buy the bonds helped increase sales. The Republicans also passed the Legal Tender Act of 1862, calling for paper money—known as greenbacks —to be printed Figure 15.11 ). Some $150 million worth of greenbacks became legal tender, and the Northern economy boomed, although high inflation also resulted. Like the Confederacy, the Union turned to conscription to provide the troops needed for the war. In March 1863, Congress passed the Enrollment Act, requiring all unmarried men between the ages of twenty and twenty-five, and all married men between the ages of thirty-five and forty-five—including immigrants who had filed for citizenship—to register with the Union to fight in the Civil War. All who registered were subject to military service, and draftees were selected by a lottery system ( Figure 15.12 ). As in the South, a loophole in the law allowed individuals to hire substitutes if they could afford it. Others could avoid enlistment by paying $300 to the federal government. In keeping with the Supreme Court decision in Dred Scott v. Sandford , African Americans were not citizens and were therefore exempt from the draft. Like the Confederacy, the Union also took the step of suspending habeas corpus rights, so those suspected of pro-Confederate sympathies could be arrested and held without being given the reason. Lincoln had selectively suspended the writ of habeas corpus in the slave state of Maryland, home to many Confederate sympathizers, in 1861 and 1862, in an effort to ensure that the Union capital would be safe. In March 1863, he signed into law the Habeas Corpus Suspension Act, giving him the power to detain suspected Confederate operatives throughout the Union. The Lincoln administration also closed down three hundred newspapers as a national security measure during the war. In both the North and the South, the Civil War dramatically increased the power of the belligerent governments. Breaking all past precedents in American history, both the Confederacy and the Union employed the power of their central governments to mobilize resources and citizens. Women’s Mobilization As men on both sides mobilized for the war, so did women. In both the North and the South, women were forced to take over farms and businesses abandoned by their husbands as they left for war. Women organized themselves into ladies’ aid societies to sew uniforms, knit socks, and raise money to purchase necessities for the troops. In the South, women took wounded soldiers into their homes to nurse. In the North, women volunteered for the United States Sanitary Commission, which formed in June 1861. They inspected military camps with the goal of improving cleanliness and reducing the number of soldiers who died from disease, the most common cause of death in the war. They also raised money to buy medical supplies and helped with the injured. Other women found jobs in the Union army as cooks and laundresses. Thousands volunteered to care for the sick and wounded in response to a call by reformer Dorothea Dix, who was placed in charge of the Union army’s nurses. According to rumor, Dix sought respectable women over the age of thirty who were “plain almost to repulsion in dress” and thus could be trusted not to form romantic liaisons with soldiers. Women on both sides also acted as spies and, disguised as men, engaged in combat. EMANCIPATION Early in the war, President Lincoln approached the issue of slavery cautiously. While he disapproved of slavery personally, he did not believe that he had the authority to abolish it. Furthermore, he feared that making the abolition of slavery an objective of the war would cause the border slave states to join the Confederacy. His one objective in 1861 and 1862 was to restore the Union. Defining American Lincoln’s Evolving Thoughts on Slavery President Lincoln wrote the following letter to newspaper editor Horace Greeley on August 22, 1862. In it, Lincoln states his position on slavery, which is notable for being a middle-of-the-road stance. Lincoln’s later public speeches on the issue take the more strident antislavery tone for which he is remembered. I would save the Union. I would save it the shortest way under the Constitution. The sooner the national authority can be restored the nearer the Union will be “the Union as it was.” If there be those who would not save the Union unless they could at the same time save Slavery, I do not agree with them. If there be those who would not save the Union unless they could at the same time destroy Slavery, I do not agree with them. My paramount object in this struggle is to save the Union, and is not either to save or destroy Slavery. If I could save the Union without freeing any slave, I would do it, and if I could save it by freeing all the slaves, I would do it, and if I could save it by freeing some and leaving others alone, I would also do that. What I do about Slavery and the colored race, I do because I believe it helps to save this Union, and what I forbear, I forbear because I do not believe it would help to save the Union. I shall do less whenever I shall believe what I am doing hurts the cause, and I shall do more whenever I shall believe doing more will help the cause. I shall try to correct errors when shown to be errors; and I shall adopt new views so fast as they shall appear to be true views. I have here stated my purpose according to my view of official duty, and I intend no modification of my oft-expressed personal wish that all men, everywhere, could be free. Yours, A. LINCOLN. How would you characterize Lincoln’s public position in August 1862? What was he prepared to do for enslaved people, and under what conditions? Since the beginning of the war, thousands of enslaved people had fled to the safety of Union lines. In May 1861, Union general Benjamin Butler and others labeled these refugees from slavery contrabands . Butler reasoned that since Southern states had left the United States, he was not obliged to follow federal fugitive slave laws. Escaped enslaved people who made it through the Union lines were shielded by the U.S. military and not returned to slavery. The intent was not only to assist them but also to deprive the South of a valuable source of manpower. Congress began to define the status of formerly enslaved people in 1861 and 1862. In August 1861, legislators approved the Confiscation Act of 1861, empowering the Union to seize property, including the enslaved, used by the Confederacy. The Republican-dominated Congress took additional steps, abolishing slavery in Washington, DC, in April 1862. Congress passed a second Confiscation Act in July 1862, which extended freedom to escaped enslaved people and those captured by Union armies. In that month, Congress also addressed the issue of slavery in the West, banning the practice in the territories. This federal law made the 1846 Wilmot Proviso and the dreams of the Free-Soil Party a reality. However, even as the Union government took steps to aid enslaved individuals and to limit the practice of slavery, it passed no measure to address the institution of slavery as a whole. Lincoln moved slowly and cautiously on the issue of abolition. His primary concern was the cohesion of the Union and the bringing of the Southern states back into the fold. However, as the war dragged on and many thousands of contrabands made their way north, Republicans in Congress continued to call for the end of slavery. Throughout his political career, Lincoln’s plans for formerly enslaved people had been to send them to Liberia. As late as August 1862, he had hoped to interest African Americans in building a colony for formerly enslaved people in Central America, an idea that found favor neither with Black leaders nor with abolitionists, and thus was abandoned by Lincoln. Responding to Congressional demands for an end to slavery, Lincoln presented an ultimatum to the Confederates on September 22, 1862, shortly after the Confederate retreat at Antietam. He gave the Confederate states until January 1, 1863, to rejoin the Union. If they did, slavery would continue in the slave states. If they refused to rejoin, however, the war would continue and all of the enslaved would be freed at its conclusion. The Confederacy took no action. It had committed itself to maintaining its independence and had no interest in the president’s ultimatum. On January 1, 1863, Lincoln made good on his promise and signed the Emancipation Proclamation . It stated “That on the first day of January, in the year of our Lord one thousand eight hundred and sixty-three, all persons held as slaves within any State or designated part of a State, the people whereof shall then be in rebellion against the United States, shall be then, thenceforward, and forever free.” The proclamation did not immediately free the those enslaved in the Confederate states. Although they were in rebellion against the United States, the lack of the Union army’s presence in such areas meant that the president’s directive could not be enforced. The proclamation also did not free those enslaved in the border states, because these states were not, by definition, in rebellion. Lincoln relied on his powers as commander-in-chief in issuing the Emancipation Proclamation. He knew the proclamation could be easily challenged in court, but by excluding the territories still outside his control, slaveholders and slave governments could not sue him. Moreover, slave states in the Union, such as Kentucky, could not sue because the proclamation did not apply to them. Slaveholders in Kentucky knew full well that if the institution were abolished throughout the South, it would not survive in a handful of border territories. Despite the limits of the proclamation, Lincoln dramatically shifted the objective of the war increasingly toward ending slavery. The Emancipation Proclamation became a monumental step forward on the road to changing the character of the United States. The proclamation generated quick and dramatic reactions. The news created euphoria among enslaved people, as it signaled the eventual end of their bondage. Predictably, Confederate leaders raged against the proclamation, reinforcing their commitment to fight to maintain slavery, the foundation of the Confederacy. In the North, opinions split widely on the issue. Abolitionists praised Lincoln’s actions, which they saw as the fulfillment of their long campaign to strike down an immoral institution. But other Northerners, especially Irish, working-class, urban dwellers loyal to the Democratic Party and others with racist beliefs, hated the new goal of emancipation and found the idea of freed slaves repugnant. At its core, much of this racism had an economic foundation: Many Northerners feared competing with emancipated people for scarce jobs. In New York City, the Emancipation Proclamation, combined with unhappiness over the Union draft, which began in March 1863, fanned the flames of White racism. Many New Yorkers supported the Confederacy for business reasons, and, in 1861, the city’s mayor actually suggested that New York City leave the Union. On July 13, 1863, two days after the first draft lottery took place, this racial hatred erupted into violence. A volunteer fire company whose commander had been drafted initiated a riot, and the violence spread quickly across the city. The rioters chose targets associated either with the Union army or with African Americans. An armory was destroyed, as was a Brooks Brothers’ store, which supplied uniforms to the army. White mobs attacked and killed Black New Yorkers and destroyed an African American orphanage ( Figure 15.13 ). On the fourth day of the riots, federal troops dispatched by Lincoln arrived in the city and ended the violence. Millions of dollars in property had been destroyed. More than one hundred people died, approximately one thousand were left injured, and about one-fifth of the city’s African American population fled New York in fear. UNION ADVANCES The war in the west continued in favor of the North in 1863. At the start of the year, Union forces controlled much of the Mississippi River. In the spring and summer of 1862, they had captured New Orleans—the most important port in the Confederacy, through which cotton harvested from all the Southern states was exported—and Memphis. Grant had then attempted to capture Vicksburg, Mississippi, a commercial center on the bluffs above the Mississippi River. Once Vicksburg fell, the Union would have won complete control over the river. A military bombardment that summer failed to force a Confederate surrender. An assault by land forces also failed in December 1862. In April 1863, the Union began a final attempt to capture Vicksburg. On July 3, after more than a month of a Union siege, during which Vicksburg’s residents hid in caves to protect themselves from the bombardment and ate their pets to stay alive, Grant finally achieved his objective. The trapped Confederate forces surrendered. The Union had succeeded in capturing Vicksburg and splitting the Confederacy ( Figure 15.14 ). This victory inflicted a serious blow to the Southern war effort. As Grant and his forces pounded Vicksburg, Confederate strategists, at the urging of General Lee, who had defeated a larger Union army at Chancellorsville, Virginia, in May 1863, decided on a bold plan to invade the North. Leaders hoped this invasion would force the Union to send troops engaged in the Vicksburg campaign east, thus weakening their power over the Mississippi. Further, they hoped the aggressive action of pushing north would weaken the Union’s resolve to fight. Lee also hoped that a significant Confederate victory in the North would convince Great Britain and France to extend support to Jefferson Davis’s government and encourage the North to negotiate peace. Beginning in June 1863, General Lee began to move the Army of Northern Virginia north through Maryland. The Union army—the Army of the Potomac—traveled east to end up alongside the Confederate forces. The two armies met at Gettysburg, Pennsylvania, where Confederate forces had gone to secure supplies. The resulting battle lasted three days, July 1–3 ( Figure 15.15 ) and remains the biggest and costliest battle ever fought in North America. The climax of the Battle of Gettysburg occurred on the third day. In the morning, after a fight lasting several hours, Union forces fought back a Confederate attack on Culp’s Hill, one of the Union’s defensive positions. To regain a perceived advantage and secure victory, Lee ordered a frontal assault, known as Pickett’s Charge (for Confederate general George Pickett), against the center of the Union lines on Cemetery Ridge. Approximately fifteen thousand Confederate soldiers took part, and more than half lost their lives, as they advanced nearly a mile across an open field to attack the entrenched Union forces. In all, more than a third of the Army of Northern Virginia had been lost, and on the evening of July 4, Lee and his men slipped away in the rain. General George Meade did not pursue them. Both sides suffered staggering losses. Total casualties numbered around twenty-three thousand for the Union and some twenty-eight thousand among the Confederates. With its defeats at Gettysburg and Vicksburg, both on the same day, the Confederacy lost its momentum. The tide had turned in favor of the Union in both the east and the west. Following the Battle of Gettysburg, the bodies of those who had fallen were hastily buried. Attorney David Wills, a resident of Gettysburg, campaigned for the creation of a national cemetery on the site of the battlefield, and the governor of Pennsylvania tasked him with creating it. President Lincoln was invited to attend the cemetery’s dedication. After the featured orator had delivered a two-hour speech, Lincoln addressed the crowd for several minutes. In his speech, known as the Gettysburg Address , which he had finished writing while a guest in David Wills’ home the day before the dedication, Lincoln invoked the Founding Fathers and the spirit of the American Revolution. The Union soldiers who had died at Gettysburg, he proclaimed, had died not only to preserve the Union, but also to guarantee freedom and equality for all. Defining American Lincoln’s Gettysburg Address Several months after the battle at Gettysburg, Lincoln traveled to Pennsylvania and, speaking to an audience at the dedication of the new Soldiers’ National Ceremony near the site of the battle, he delivered his now-famous Gettysburg Address to commemorate the turning point of the war and the soldiers whose sacrifices had made it possible. The two-minute speech was politely received at the time, although press reactions split along party lines. Upon receiving a letter of congratulations from Massachusetts politician and orator William Everett, whose speech at the ceremony had lasted for two hours, Lincoln said he was glad to know that his brief address, now virtually immortal, was not “a total failure.” Four score and seven years ago our fathers brought forth on this continent, a new nation, conceived in Liberty, and dedicated to the proposition that all men are created equal. Now we are engaged in a great civil war, testing whether that nation, or any nation so conceived and so dedicated, can long endure. We are met on a great battle-field of that war. We have come to dedicate a portion of that field, as a final resting place for those who here gave their lives that that nation might live. It is altogether fitting and proper that we should do this. It is for us the living . . . to be here dedicated to the great task remaining before us—that from these honored dead we take increased devotion to that cause for which they gave the last full measure of devotion—that we here highly resolve that these dead shall not have died in vain—that this nation, under God, shall have a new birth of freedom—and that government of the people, by the people, for the people, shall not perish from the earth. —Abraham Lincoln, Gettysburg Address, November 19, 1863 What did Lincoln mean by “a new birth of freedom”? What did he mean when he said “a government of the people, by the people, for the people, shall not perish from the earth”? 15.4 The Union Triumphant Learning Objectives By the end of this section, you will be able to: Describe the reasons why many Americans doubted that Abraham Lincoln would be reelected Explain how the Union forces overpowered the Confederacy By the outset of 1864, after three years of war, the Union had mobilized its resources for the ongoing struggle on a massive scale. The government had overseen the construction of new railroad lines and for the first time used standardized rail tracks that allowed the North to move men and materials with greater ease. The North’s economy had shifted to a wartime model. The Confederacy also mobilized, perhaps to a greater degree than the Union, its efforts to secure independence and maintain slavery. Yet the Confederacy experienced ever-greater hardships after years of war. Without the population of the North, it faced a shortage of manpower. The lack of industry, compared to the North, undercut the ability to sustain and wage war. Rampant inflation as well as food shortages in the South lowered morale. THE RELATIONSHIP WITH EUROPE From the beginning of the war, the Confederacy placed great hope in being recognized and supported by Great Britain and France. European intervention in the conflict remained a strong possibility, but when it did occur, it was not in a way anticipated by either the Confederacy or the Union. Napoleon III of France believed the Civil War presented an opportunity for him to restore a French empire in the Americas. With the United States preoccupied, the time seemed ripe for action. Napoleon’s target was Mexico, and in 1861, a large French fleet took Veracruz. The French then moved to capture Mexico City, but the advance came to an end when Mexican forces defeated the French in 1862. Despite this setback, France eventually did conquer Mexico, establishing a regime that lasted until 1867. Rather than coming to the aid of the Confederacy, France used the Civil War to provide a pretext for efforts to reestablish its former eighteenth-century colonial holdings. Still, the Confederacy had great confidence that it would find an ally in Great Britain despite the antislavery sentiment there. Southerners hoped Britain’s dependence on cotton for its textile mills would keep the country on their side. The fact that the British proved willing to build and sell ironclad ships intended to smash through the Union naval blockade further raised Southern hopes. The Confederacy purchased two of these armored blockade runners, the CSS Florida and the CSS Alabama . Both were destroyed during the war. The Confederacy’s staunch commitment to slavery eventually worked against British recognition and support, since Great Britain had abolished slavery in 1833. The 1863 Emancipation Proclamation ended any doubts the British had about the goals of the Union cause. In the aftermath of the proclamation, many in Great Britain cheered for a Union victory. Ultimately, Great Britain, like France, disappointed the Confederacy’s hope of an alliance, leaving the outnumbered and out-resourced states that had left the Union to fend for themselves. AFRICAN AMERICAN SOLDIERS At the beginning of the war, in 1861 and 1862, Union forces had used contrabands, or escaped enslaved people, for manual labor. The Emancipation Proclamation, however, led to the enrollment of African American men as Union soldiers. Huge numbers of formerly enslaved as well as free Black people from the North enlisted, and by the end of the war in 1865, their numbers had swelled to over 190,000. Racism among White people in the Union army ran deep, however, fueling the belief that Black soldiers could never be effective or trustworthy. The Union also feared for the fate of captured Black soldiers. Although many Black soldiers saw combat duty, these factors affected the types of tasks assigned to them. Many Black regiments were limited to hauling supplies, serving as cooks, digging trenches, and doing other types of labor, rather than serving on the battlefield ( Figure 15.16 ). African American soldiers also received lower wages than their White counterparts: ten dollars per month, with three dollars deducted for clothing. White soldiers, in contrast, received thirteen dollars monthly, with no deductions. Abolitionists and their Republican supporters in Congress worked to correct this discriminatory practice, and in 1864, Black soldiers began to receive the same pay as White soldiers plus retroactive pay to 1863 ( Figure 15.17 ). For their part, African American soldiers welcomed the opportunity to prove themselves. Some 85 percent were formerly enslaved people who were fighting for the liberation of all of the enslaved and the end of slavery. When given the opportunity to serve, many Black regiments did so heroically. One such regiment, the Fifty-Fourth Regiment of Massachusetts Volunteers, distinguished itself at Fort Wagner in South Carolina by fighting valiantly against an entrenched Confederate position. They willingly gave their lives for the cause. The Confederacy, not surprisingly, showed no mercy to African American troops. In April 1864, Southern forces attempted to take Fort Pillow in Tennessee from the Union forces that had captured it in 1862. Confederate troops under Major General Nathan Bedford Forrest, the future founder of the Ku Klux Klan, quickly overran the fort, and the Union defenders surrendered. Instead of taking the African American soldiers prisoner, as they did the White soldiers, the Confederates executed them. The massacre outraged the North, and the Union refused to engage in any future exchanges of prisoners with the Confederacy. THE CAMPAIGNS OF 1864 AND 1865 In the final years of the war, the Union continued its efforts on both the eastern and western fronts while bringing the war into the Deep South. Union forces increasingly engaged in total war, not distinguishing between military and civilian targets. They destroyed everything that lay in their path, committed to breaking the will of the Confederacy and forcing an end to the war. General Grant, mastermind of the Vicksburg campaign, took charge of the war effort. He understood the advantage of having large numbers of soldiers at his disposal and recognized that Union soldiers could be replaced, whereas the Confederates, whose smaller population was feeling the strain of the years of war, could not. Grant thus pushed forward relentlessly, despite huge losses of men. In 1864, Grant committed his forces to destroying Lee’s army in Virginia. In the Virginia campaign, Grant hoped to use his larger army to his advantage. But at the Battle of the Wilderness, fought from May 5 to May 7, Confederate forces stopped Grant’s advance. Rather than retreating, he pushed forward. At the Battle of Spotsylvania on May 8 through 12, Grant again faced determined Confederate resistance, and again his advance was halted. As before, he renewed the Union campaign. At the Battle of Cold Harbor in early June, Grant had between 100,000 and 110,000 soldiers, whereas the Confederates had slightly more than half that number. Again, the Union advance was halted, if only momentarily, as Grant awaited reinforcements. An attack on the Confederate position on June 3 resulted in heavy casualties for the Union, and nine days later, Grant led his army away from Cold Harbor to Petersburg, Virginia, a rail center that supplied Richmond. The immense losses that Grant’s forces suffered severely hurt Union morale. The war seemed unending, and with the tremendous loss of life, many in the North began to question the war and desire peace. Undaunted by the changing opinion in the North and hoping to destroy the Confederate rail network in the Upper South, however, Grant laid siege to Petersburg for nine months. As the months wore on, both sides dug in, creating miles of trenches and gun emplacements. The other major Union campaigns of 1864 were more successful and gave President Lincoln the advantage that he needed to win reelection in November. In August 1864, the Union navy captured Mobile Bay. General Sherman invaded the Deep South, advancing slowly from Tennessee into Georgia, confronted at every turn by the Confederates, who were commanded by Johnston. When President Davis replaced Johnston with General John B. Hood, the Confederates made a daring but ultimately costly direct attack on the Union army that failed to drive out the invaders. Atlanta fell to Union forces on September 2, 1864. The fall of Atlanta held tremendous significance for the war-weary Union and helped to reverse the North’s sinking morale. In keeping with the logic of total war, Sherman’s forces cut a swath of destruction to Savannah. On Sherman’s March to the Sea , the Union army, seeking to demoralize the South, destroyed everything in its path, despite strict instructions regarding the preservation of civilian property. Although towns were left standing, houses and barns were burned. Homes were looted, food was stolen, crops were destroyed, orchards were burned, and livestock was killed or confiscated. Savannah fell on December 21, 1864—a Christmas gift for Lincoln, Sherman proclaimed. In 1865, Sherman’s forces invaded South Carolina, capturing Charleston and Columbia. In Columbia, the state capital, the Union army burned slaveholders’ homes and destroyed much of the city. From South Carolina, Sherman’s force moved north in an effort to join Grant and destroy Lee’s army. My Story Dolly Sumner Lunt on Sherman’s March to the Sea The following account is by Dolly Sumner Lunt, a widow who ran her Georgia cotton plantation after the death of her husband. She describes General Sherman’s march to Savannah, where he enacted the policy of total war by burning and plundering the landscape to inhibit the Confederates’ ability to keep fighting. Alas! little did I think while trying to save my house from plunder and fire that they were forcing my boys [slaves] from home at the point of the bayonet. One, Newton, jumped into bed in his cabin, and declared himself sick. Another crawled under the floor,—a lame boy he was,—but they pulled him out, placed him on a horse, and drove him off. Mid, poor Mid! The last I saw of him, a man had him going around the garden, looking, as I thought, for my sheep, as he was my shepherd. Jack came crying to me, the big tears coursing down his cheeks, saying they were making him go. I said: ‘Stay in my room.’ But a man followed in, cursing him and threatening to shoot him if he did not go; so poor Jack had to yield. . . . Sherman himself and a greater portion of his army passed my house that day. All day, as the sad moments rolled on, were they passing not only in front of my house, but from behind; they tore down my garden palings, made a road through my back-yard and lot field, driving their stock and riding through, tearing down my fences and desolating my home—wantonly doing it when there was no necessity for it. . . . About ten o’clock they had all passed save one, who came in and wanted coffee made, which was done, and he, too, went on. A few minutes elapsed, and two couriers riding rapidly passed back. Then, presently, more soldiers came by, and this ended the passing of Sherman’s army by my place, leaving me poorer by thirty thousand dollars than I was yesterday morning. And a much stronger Rebel! According to this account, what was the reaction of enslaved people to the arrival of the Union forces? What did the Union forces do with the enslaved? For Lunt, did the strategy of total war work as planned? THE ELECTION OF 1864 Despite the military successes for the Union army in 1863, in 1864, Lincoln’s status among many Northern voters plummeted. Citing the suspension of the writ of habeas corpus, many saw him as a dictator, bent on grabbing power while senselessly and uncaringly drafting more young men into combat. Arguably, his greatest liability, however, was the Emancipation Proclamation and the enlistment of African American soldiers. Many Whites in the North found this deeply offensive, since they still believed in racial inequality. The 1863 New York City Draft Riots illustrated the depth of White anger. Northern Democrats railed against Lincoln and the war. Republicans labeled these vocal opponents of the President Copperheads , a term that many antiwar Democrats accepted. As the anti-Lincoln poster below illustrates, his enemies tried to paint him as an untrustworthy and suspect leader ( Figure 15.18 ). It seemed to most in the North that the Democratic candidate, General George B. McClellan, who did not support abolition and was replaced with another commander by Lincoln, would win the election. The Republican Party also split over the issue of reelecting Lincoln. Those who found him timid and indecisive, and favored extending full rights to African Americans, as well as completely refashioning the South after its defeat, earned the name Radicals. A moderate faction of Republicans opposed the Radicals. For his part, Lincoln did not align himself with either group. The tide of the election campaign turned in favor of Lincoln, however, in the fall of 1864. Above all else, Union victories, including the fall of Atlanta in September and General Philip Sheridan’s successes in the Shenandoah Valley of Virginia, bolstered Lincoln’s popularity and his reelection bid. In November 1864, despite earlier forecasts to the contrary, Lincoln was reelected. Lincoln won all but three states—New Jersey and the border states of Delaware and Kentucky. To the chagrin of his opponent, McClellan, even Union army troops voted overwhelmingly for the incumbent President. THE WAR ENDS By the spring of 1865, it had become clear to both sides that the Confederacy could not last much longer. Most of its major cities, ports, and industrial centers—Atlanta, Savannah, Charleston, Columbia, Mobile, New Orleans, and Memphis—had been captured. In April 1865, Lee had abandoned both Petersburg and Richmond. His goal in doing so was to unite his depleted army with Confederate forces commanded by General Johnston. Grant effectively cut him off. On April 9, 1865, Lee surrendered to Grant at Appomattox Court House in Virginia ( Figure 15.19 ). By that time, he had fewer than 35,000 soldiers, while Grant had some 100,000. Meanwhile, Sherman’s army proceeded to North Carolina, where General Johnston surrendered on April 19, 1865. The Civil War had come to an end. The war had cost the lives of more than 600,000 soldiers. Many more had been wounded. Thousands of women were left widowed. Children were left without fathers, and many parents were deprived of a source of support in their old age. In some areas, where local volunteer units had marched off to battle, never to return, an entire generation of young women was left without marriage partners. Millions of dollars’ worth of property had been destroyed, and towns and cities were laid to waste. With the conflict finally over, the very difficult work of reconciling North and South and reestablishing the United States lay ahead.
microbiology
Summary 4.1 Prokaryote Habitats, Relationships, and Microbiomes Prokaryotes are unicellular microorganisms whose cells have no nucleus. Prokaryotes can be found everywhere on our planet, even in the most extreme environments. Prokaryotes are very flexible metabolically, so they are able to adjust their feeding to the available natural resources. Prokaryotes live in communities that interact among themselves and with large organisms that they use as hosts (including humans). The totality of forms of prokaryotes (particularly bacteria) living on the human body is called the human microbiome, which varies between regions of the body and individuals, and changes over time. The totality of forms of prokaryotes (particularly bacteria) living in a certain region of the human body (e.g., mouth, throat, gut, eye, vagina) is called the microbiota of this region. Prokaryotes are classified into domains Archaea and Bacteria. In recent years, the traditional approaches to classification of prokaryotes have been supplemented by approaches based on molecular genetics. 4.2 Proteobacteria Proteobacteria is a phylum of gram-negative bacteria discovered by Carl Woese in the 1980s based on nucleotide sequence homology. Proteobacteria are further classified into the classes alpha-, beta-, gamma-, delta- and epsilonproteobacteria, each class having separate orders, families, genera, and species. Alphaproteobacteria include several obligate and facultative intracellular pathogens, including the rickettsias. Some Alphaproteobacteria can convert atmospheric nitrogen to nitrites, making nitrogen usable for other forms of life. Betaproteobacteria are a diverse group of bacteria that include human pathogens of the genus Neisseria and the species Bordetella pertussis . Gammaproteobacteria are the largest and the most diverse group of Proteobacteria. Many are human pathogens that are aerobes or facultative anaerobes. Some Gammaproteobacteria are enteric bacteria that may be coliform or noncoliform. Escherichia coli , a member of Gammaproteobacteria, is perhaps the most studied bacterium. Deltaproteobacteria make up a small group able to reduce sulfate or elemental sulfur. Some are scavengers and form myxospores, with multicellular fruiting bodies. Epsilonproteobacteria make up the smallest group of Proteobacteria. The genera Campylobacter and Helicobacter are human pathogens. 4.3 Nonproteobacteria Gram-Negative Bacteria and Phototrophic Bacteria Gram-negative nonproteobacteria include the taxa spirochetes ; the Chlamydia , Cytophaga , Fusobacterium , Bacteroides group; Planctomycetes; and many representatives of phototrophic bacteria. Spirochetes are motile, spiral bacteria with a long, narrow body; they are difficult or impossible to culture. Several genera of spirochetes contain human pathogens that cause such diseases as syphilis and Lyme disease. Cytophaga , Fusobacterium , and Bacteroides are classified together as a phylum called the CFB group . They are rod-shaped anaerobic organoheterotrophs and avid fermenters. Cytophaga are aquatic bacteria with the gliding motility. Fusobacteria inhabit the human mouth and may cause severe infectious diseases. Bacteroides are present in vast numbers in the human gut, most of them being mutualistic but some are pathogenic. Planctomycetes are aquatic bacteria that reproduce by budding; they may form large colonies, and develop a holdfast. Phototrophic bacteria are not a taxon but, rather, a group categorized by their ability to use the energy of sunlight. They include Proteobacteria and nonproteobacteria, as well as sulfur and nonsulfur bacteria colored purple or green. Sulfur bacteria perform anoxygenic photosynthesis, using sulfur compounds as donors of electrons, whereas nonsulfur bacteria use organic compounds (succinate, malate) as donors of electrons. Some phototrophic bacteria are able to fix nitrogen, providing the usable forms of nitrogen to other organisms. Cyanobacteria are oxygen-producing bacteria thought to have played a critical role in the forming of the earth’s atmosphere. 4.4 Gram-Positive Bacteria Gram-positive bacteria are a very large and diverse group of microorganisms. Understanding their taxonomy and knowing their unique features is important for diagnostics and treatment of infectious diseases. Gram-positive bacteria are classified into high G+C gram-positive and low G+C gram-positive bacteria, based on the prevalence of guanine and cytosine nucleotides in their genome Actinobacteria is the taxonomic name of the class of high G+C gram-positive bacteria. This class includes the genera Actinomyces, Arthrobacter, Corynebacterium, Frankia, Gardnerella, Micrococcus, Mycobacterium, Nocardia , Propionibacterium, Rhodococcus, and Streptomyces . Some representatives of these genera are used in industry; others are human or animal pathogens. Examples of high G+C gram-positive bacteria that are human pathogens include Mycobacterium tuberculosis , which causes tuberculosis; M. leprae , which causes leprosy (Hansen’s disease); and Corynebacterium diphtheriae , which causes diphtheria. Clostridia spp. are low G+C gram-positive bacteria that are generally obligate anaerobes and can form endospores. Pathogens in this genus include C. perfringens (gas gangrene), C. tetani (tetanus), and C. botulinum (botulism). Lactobacillales include the genera Enterococcus , Lactobacillus , Leuconostoc , and Streptococcus. Streptococcus is responsible for many human diseases, including pharyngitis (strep throat), scarlet fever, rheumatic fever, glomerulonephritis, pneumonia, and other respiratory infections. Bacilli is a taxonomic class of low G+C gram-positive bacteria that include rod-shaped and coccus-shaped species, including the genera Bacillus and Staphylococcus . B. anthracis causes anthrax, B. cereus may cause opportunistic infections of the gastrointestinal tract, and S. aureus strains can cause a wide range of infections and diseases, many of which are highly resistant to antibiotics. Mycoplasma spp. are very small, pleomorphic low G+C gram-positive bacteria that lack cell walls. M. pneumoniae causes atypical pneumonia. 4.5 Deeply Branching Bacteria Deeply branching bacteria are phylogenetically the most ancient forms of life, being the closest to the last universal common ancestor. Deeply branching bacteria include many species that thrive in extreme environments that are thought to resemble conditions on earth billions of years ago Deeply branching bacteria are important for our understanding of evolution; some of them are used in industry 4.6 Archaea Archaea are unicellular, prokaryotic microorganisms that differ from bacteria in their genetics, biochemistry, and ecology. Some archaea are extremophiles, living in environments with extremely high or low temperatures, or extreme salinity. Only archaea are known to produce methane. Methane-producing archaea are called methanogens . Halophilic archaea prefer a concentration of salt close to saturation and perform photosynthesis using bacteriorhodopsin. Some archaea, based on fossil evidence, are among the oldest organisms on earth. Archaea do not live in great numbers in human microbiomes and are not known to cause disease.
Chapter Outline 4.1 Prokaryote Habitats, Relationships, and Microbiomes 4.2 Proteobacteria 4.3 Nonproteobacteria Gram-Negative Bacteria and Phototrophic Bacteria 4.4 Gram-Positive Bacteria 4.5 Deeply Branching Bacteria 4.6 Archaea Introduction Scientists have studied prokaryotes for centuries, but it wasn’t until 1966 that scientist Thomas Brock (1926–) discovered that certain bacteria can live in boiling water. This led many to wonder whether prokaryotes may also live in other extreme environments, such as at the bottom of the ocean, at high altitudes, or inside volcanoes, or even on other planets. Prokaryotes have an important role in changing, shaping, and sustaining the entire biosphere. They can produce proteins and other substances used by molecular biologists in basic research and in medicine and industry. For example, the bacterium Shewanella lives in the deep sea, where oxygen is scarce. It grows long appendages, which have special sensors used to seek the limited oxygen in its environment. It can also digest toxic waste and generate electricity. Other species of prokaryotes can produce more oxygen than the entire Amazon rainforest, while still others supply plants, animals, and humans with usable forms of nitrogen; and inhabit our body, protecting us from harmful microorganisms and producing some vitally important substances. This chapter will examine the diversity, structure, and function of prokaryotes.
[ { "answer": { "ans_choice": 1, "ans_text": "B" }, "bloom": null, "hl_context": "All living organisms are classified into three domains of life : Archaea , Bacteria , and Eukarya . In this chapter , we will focus on the domains Archaea and Bacteria . <hl> Archaea and bacteria are unicellular prokaryotic organisms . <hl> <hl> Unlike eukaryotes , they have no nuclei or any other membrane-bound organelles . <hl>", "hl_sentences": "Archaea and bacteria are unicellular prokaryotic organisms . Unlike eukaryotes , they have no nuclei or any other membrane-bound organelles .", "question": { "cloze_format": "The term prokaryotes refers to ___.", "normal_format": "The term prokaryotes refers to which of the following?", "question_choices": [ "very small organisms", "unicellular organisms that have no nucleus", "multicellular organisms", "cells that resemble animal cells more than plant cells" ], "question_id": "fs-id1172100562431", "question_text": "The term prokaryotes refers to which of the following?" }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 2, "ans_text": "C" }, "bloom": null, "hl_context": "<hl> One important achievement of the Human Microbiome Project is establishing the first reference database on microorganisms living in and on the human body . <hl> Many of the microbes in the microbiome are beneficial , but some are not . It was found , somewhat unexpectedly , that all of us have some serious microbial pathogens in our microbiota . For example , the conjunctiva of the human eye contains 24 genera of bacteria and numerous pathogenic species . 7 A healthy human mouth contains a number of species of the genus Streptococcus , including pathogenic species S . pyogenes and S . pneumoniae . 8 This raises the question of why certain prokaryotic organisms exist commensally in certain individuals but act as deadly pathogens in others . Also unexpected was the number of organisms that had never been cultured . For example , in one metagenomic study of the human gut microbiota , 174 new species of bacteria were identified . 9 7 Q . Dong et al . “ Diversity of Bacteria at Healthy Human Conjunctiva . ” Investigative Ophthalmology & Visual Science 52 no . 8 ( 2011 ): 5408 – 5413 . 8 F . E . Dewhirst et al . “ The Human Oral Microbiome . ” Journal of Bacteriology 192 no . 19 ( 2010 ): 5002 – 5017 . 9 J . C . Lagier et al . “ Microbial Culturomics : Paradigm Shift in the Human Gut Microbiome Study . ” Clinical Microbiology and Infection 18 no . 12 ( 2012 ): 1185 – 1193 . Scientists have coined the term microbiome to refer to all prokaryotic and eukaryotic microorganisms and their genetic material that are associated with a certain organism or environment . <hl> Within the human microbiome , there are resident microbiota and transient microbiota . <hl> <hl> The resident microbiota consists of microorganisms that constantly live in or on our bodies . <hl> <hl> The term transient microbiota refers to microorganisms that are only temporarily found in the human body , and these may include pathogenic microorganisms . <hl> Hygiene and diet can alter both the resident and transient microbiota . The resident microbiota is amazingly diverse , not only in terms of the variety of species but also in terms of the preference of different microorganisms for different areas of the human body . For example , in the human mouth , there are thousands of commensal or mutualistic species of bacteria . Some of these bacteria prefer to inhabit the surface of the tongue , whereas others prefer the internal surface of the cheeks , and yet others prefer the front or back teeth or gums . The inner surface of the cheek has the least diverse microbiota because of its exposure to oxygen . By contrast , the crypts of the tongue and the spaces between teeth are two sites with limited oxygen exposure , so these sites have more diverse microbiota , including bacteria living in the absence of oxygen ( e . g . , Bacteroides , Fusobacterium ) . Differences in the oral microbiota between randomly chosen human individuals are also significant . Studies have shown , for example , that the prevalence of such bacteria as Streptococcus , Haemophilus , Neisseria , and others was dramatically different when compared between individuals . 4 4 E . M . Bik et al . “ Bacterial Diversity in the Oral Cavity of 10 Healthy Individuals . ” The ISME Journal 4 no . 8 ( 2010 ): 962 – 974 .", "hl_sentences": "One important achievement of the Human Microbiome Project is establishing the first reference database on microorganisms living in and on the human body . Within the human microbiome , there are resident microbiota and transient microbiota . The resident microbiota consists of microorganisms that constantly live in or on our bodies . The term transient microbiota refers to microorganisms that are only temporarily found in the human body , and these may include pathogenic microorganisms .", "question": { "cloze_format": "The term microbiota refers to ___ .", "normal_format": "The term microbiota refers to which of the following?", "question_choices": [ "all microorganisms of the same species", "all of the microorganisms involved in a symbiotic relationship", "all microorganisms in a certain region of the human body", "all microorganisms in a certain geographic region" ], "question_id": "fs-id1172100771337", "question_text": "The term microbiota refers to which of the following?" }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 1, "ans_text": "B" }, "bloom": null, "hl_context": "When two species benefit from each other , the symbiosis is called mutualism ( or syntropy , or crossfeeding ) . For example , humans have a mutualistic relationship with the bacterium Bacteroides thetaiotaomicron , which lives in the intestinal tract . Bacteroides thetaiotaomicron digests complex polysaccharide plant materials that human digestive enzymes cannot break down , converting them into monosaccharides that can be absorbed by human cells . Humans also have a mutualistic relationship with certain strains of Escherichia coli , another bacterium found in the gut . E . coli relies on intestinal contents for nutrients , and humans derive certain vitamins from E . coli , particularly vitamin K , which is required for the formation of blood clotting factors . ( This is only true for some strains of E . coli , however . Other strains are pathogenic and do not have a mutualistic relationship with humans . ) A type of symbiosis in which one population harms another but remains unaffected itself is called amensalism . In the case of bacteria , some amensalist species produce bactericidal substances that kill other species of bacteria . The microbiota of the skin is composed of a variety of bacterial species , including Staphylococcus epidermidis and Propionibacterium acnes . Although both species have the potential to cause infectious diseases when protective barriers are breached , they both produce a variety of antibacterial bacteriocins and bacteriocin-like compounds . S . epidermidis and P . acnes are unaffected by the bacteriocins and bacteriocin-like compounds they produce , but these compounds can target and kill other potential pathogens . <hl> In another type of symbiosis , called commensalism , one organism benefits while the other is unaffected . <hl> This occurs when the bacterium Staphylococcus epidermidis uses the dead cells of the human skin as nutrients . Billions of these bacteria live on our skin , but in most cases ( especially when our immune system is healthy ) , we do not react to them in any way . S . epidermidis provides an excellent example of how the classifications of symbiotic relationships are not always distinct . One could also consider the symbiotic relationship of S . epidermidis with humans as mutualism . Humans provide a food source of dead skin cells to the bacterium , and in turn the production of bacteriocin can provide an defense against potential pathogens . If neither of the symbiotic organisms is affected in any way , we call this type of symbiosis neutralism . An example of neutralism is the coexistence of metabolically active ( vegetating ) bacteria and endospores ( dormant , metabolically passive bacteria ) . For example , the bacterium Bacillus anthracis typically forms endospores in soil when conditions are unfavorable . If the soil is warmed and enriched with nutrients , some B . anthracis endospores germinate and remain in symbiosis with other species of endospores that have not germinated . A type of symbiosis in which one organism benefits while harming the other is called parasitism . The relationship between humans and many pathogenic prokaryotes can be characterized as parasitic because these organisms invade the body , producing toxic substances or infectious diseases that cause harm . Diseases such as tetanus , diphtheria , pertussis , tuberculosis , and leprosy all arise from interactions between bacteria and humans . <hl> Prokaryotes live in a community , or a group of interacting populations of organisms . <hl> A population is a group of individual organisms belonging to the same biological species and limited to a certain geographic area . Populations can have cooperative interactions , which benefit the populations , or competitive interactions , in which one population competes with another for resources . The study of these interactions between microbial populations and their environment is called microbial ecology . <hl> Any interaction between different species that are associated with each other within a community is called symbiosis . <hl> Such interactions fall along a continuum between opposition and cooperation . Interactions in a symbiotic relationship may be beneficial or harmful , or have no effect on one or both of the species involved . Table 4.1 summarizes the main types of symbiotic interactions among prokaryotes .", "hl_sentences": "In another type of symbiosis , called commensalism , one organism benefits while the other is unaffected . Prokaryotes live in a community , or a group of interacting populations of organisms . Any interaction between different species that are associated with each other within a community is called symbiosis .", "question": { "cloze_format": "___ refers to the type of interaction between two prokaryotic populations in which one population benefits and the other is not affected.", "normal_format": "Which of the following refers to the type of interaction between two prokaryotic populations in which one population benefits and the other is not affected?", "question_choices": [ "mutualism", "commensalism", "parasitism", "neutralism" ], "question_id": "fs-id1172098549514", "question_text": "Which of the following refers to the type of interaction between two prokaryotic populations in which one population benefits and the other is not affected?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 0, "ans_text": "A" }, "bloom": null, "hl_context": "In 1987 , the American microbiologist Carl Woese ( 1928 – 2012 ) suggested that a large and diverse group of bacteria that he called “ purple bacteria and their relatives ” should be defined as a separate phylum within the domain Bacteria based on the similarity of the nucleotide sequences in their genome . <hl> 10 This phylum of gram-negative bacteria subsequently received the name Proteobacteria . <hl> It includes many bacteria that are part of the normal human microbiota as well as many pathogens . The Proteobacteria are further divided into five classes : Alphaproteobacteria , Betaproteobacteria , Gammaproteobacteria , Deltaproteobacteria , and Epsilonproteobacteria ( Appendix D ) . 10 C . R . Woese . “ Bacterial Evolution . ” Microbiological Review 51 no . 2 ( 1987 ): 221 – 271 .", "hl_sentences": "10 This phylum of gram-negative bacteria subsequently received the name Proteobacteria .", "question": { "cloze_format": "___ describes Proteobacteria in domain Bacteria.", "normal_format": "Which of the following describes Proteobacteria in domain Bacteria?", "question_choices": [ "phylum", "class", "species", "genus" ], "question_id": "fs-id1172098559637", "question_text": "Which of the following describes Proteobacteria in domain Bacteria?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 0, "ans_text": "A" }, "bloom": null, "hl_context": "<hl> Obligate intracellular bacteria ; transmitted by ticks ; may cause Rocky Mountain spotted fever and typhus <hl> <hl> Gram-negative , pleomorphic , flagellated coccobacillus <hl> <hl> Bartonella <hl>", "hl_sentences": "Obligate intracellular bacteria ; transmitted by ticks ; may cause Rocky Mountain spotted fever and typhus Gram-negative , pleomorphic , flagellated coccobacillus Bartonella", "question": { "cloze_format": "The Alphaproteobacteria that is the cause of Rocky Mountain spotted fever and typhus is ___ .", "normal_format": "Which of the following Alphaproteobacteria is the cause of Rocky Mountain spotted fever and typhus?", "question_choices": [ "Bartonella", "Coxiella", "Rickettsia", "Ehrlichia", "Brucella" ], "question_id": "fs-id1172098544345", "question_text": "Which of the following Alphaproteobacteria is the cause of Rocky Mountain spotted fever and typhus?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 3, "ans_text": "D" }, "bloom": null, "hl_context": "<hl> Neisseria <hl> <hl> Leptothrix <hl> <hl> Bordetella <hl> <hl> Class Betaproteobacteria <hl>", "hl_sentences": "Neisseria Leptothrix Bordetella Class Betaproteobacteria", "question": { "cloze_format": "Class Betaproteobacteria includes all but the genera of ___.", "normal_format": "Class Betaproteobacteria includes all but which of the following genera?", "question_choices": [ "Neisseria.", "Bordetella.", "Leptothrix.", "Campylobacter." ], "question_id": "fs-id1172098564103", "question_text": "Class Betaproteobacteria includes all but which of the following genera?" }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 2, "ans_text": "C" }, "bloom": null, "hl_context": "The Pasteurellaceae also includes several clinically relevant genera and species . This family includes several bacteria that are human and / or animal pathogens . For example , Pasteurella haemolytica causes severe pneumonia in sheep and goats . P . multocida is a species that can be transmitted from animals to humans through bites , causing infections of the skin and deeper tissues . <hl> The genus Haemophilus contains two human pathogens , H . influenzae and H . ducreyi . <hl> Despite its name , H . influenzae does not cause influenza ( which is a viral disease ) . <hl> H . influenzae can cause both upper and lower respiratory tract infections , including sinusitis , bronchitis , ear infections , and pneumonia . <hl> Before the development of effective vaccination , strains of H . influenzae were a leading cause of more invasive diseases , like meningitis in children . H . ducreyi causes the STI known as chancroid .", "hl_sentences": "The genus Haemophilus contains two human pathogens , H . influenzae and H . ducreyi . H . influenzae can cause both upper and lower respiratory tract infections , including sinusitis , bronchitis , ear infections , and pneumonia .", "question": { "cloze_format": "Haemophilus influenzae is a common cause of ___ .", "normal_format": "Haemophilus influenzae is a common cause of which of the following?", "question_choices": [ "influenza", "dysentery", "upper respiratory tract infections", "hemophilia" ], "question_id": "fs-id1172100577825", "question_text": "Haemophilus influenzae is a common cause of which of the following?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 1, "ans_text": "B" }, "bloom": null, "hl_context": "Spirochetes are characterized by their long ( up to 250 μm ) , spiral-shaped bodies . Most spirochetes are also very thin , which makes it difficult to examine gram-stained preparations under a conventional brightfield microscope . Darkfield fluorescent microscopy is typically used instead . <hl> Spirochetes are also difficult or even impossible to culture . <hl> <hl> They are highly motile , using their axial filament to propel themselves . <hl> The axial filament is similar to a flagellum , but it wraps around the cell and runs inside the cell body of a spirochete in the periplasmic space between the outer membrane and the plasma membrane ( Figure 4.13 ) .", "hl_sentences": "Spirochetes are also difficult or even impossible to culture . They are highly motile , using their axial filament to propel themselves .", "question": { "cloze_format": "The ___ is the organelle that spirochetes use to propel themselves.", "normal_format": "Which of the following is the organelle that spirochetes use to propel themselves?", "question_choices": [ "plasma membrane", "axial filament", "pilum", "fimbria" ], "question_id": "fs-id1172100831616", "question_text": "Which of the following is the organelle that spirochetes use to propel themselves?" }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 3, "ans_text": "D" }, "bloom": null, "hl_context": "Cytophaga are motile aquatic bacteria that glide . Fusobacteria inhabit the human mouth and may cause severe infectious diseases . <hl> The largest genus of the CFB group is Bacteroides , which includes dozens of species that are prevalent inhabitants of the human large intestine , making up about 30 % of the entire gut microbiome ( Figure 4.14 ) . <hl> One gram of human feces contains up to 100 billion Bacteroides cells . Most Bacteroides are mutualistic . They benefit from nutrients they find in the gut , and humans benefit from their ability to prevent pathogens from colonizing the large intestine . Indeed , when populations of Bacteroides are reduced in the gut — as often occurs when a patient takes antibiotics — the gut becomes a more favorable environment for pathogenic bacteria and fungi , which can cause secondary infections .", "hl_sentences": "The largest genus of the CFB group is Bacteroides , which includes dozens of species that are prevalent inhabitants of the human large intestine , making up about 30 % of the entire gut microbiome ( Figure 4.14 ) .", "question": { "cloze_format": "The bacteria that are the most prevalent in the human gut are ___.", "normal_format": "Which of the following bacteria are the most prevalent in the human gut?", "question_choices": [ "cyanobacteria", "staphylococci", "Borrelia", "Bacteroides" ], "question_id": "fs-id1172100770659", "question_text": "Which of the following bacteria are the most prevalent in the human gut?" }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 0, "ans_text": "A" }, "bloom": null, "hl_context": "The green nonsulfur bacteria are similar to green sulfur bacteria but they use substrates other than sulfides for oxidation . Chloroflexus is an example of a green nonsulfur bacterium . It often has an orange color when it grows in the dark , but it becomes green when it grows in sunlight . <hl> It stores bacteriochlorophyll in chlorosomes , similar to Chlorobium , and performs anoxygenic photosynthesis , using organic sulfites ( low concentrations ) or molecular hydrogen as electron donors , so it can survive in the dark if oxygen is available . <hl> Chloroflexus does not have flagella but can glide , like Cytophaga . It grows at a wide range of temperatures , from 35 ° C to 70 ° C , thus can be thermophilic .", "hl_sentences": "It stores bacteriochlorophyll in chlorosomes , similar to Chlorobium , and performs anoxygenic photosynthesis , using organic sulfites ( low concentrations ) or molecular hydrogen as electron donors , so it can survive in the dark if oxygen is available .", "question": { "cloze_format": "___ refers to photosynthesis performed by bacteria with the use of water as the donor of electrons.", "normal_format": "Which of the following refers to photosynthesis performed by bacteria with the use of water as the donor of electrons?", "question_choices": [ "oxygenic", "anoxygenic", "heterotrophic", "phototrophic" ], "question_id": "fs-id1172100936469", "question_text": "Which of the following refers to photosynthesis performed by bacteria with the use of water as the donor of electrons?" }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 0, "ans_text": "A" }, "bloom": null, "hl_context": "<hl> Based on their prevalence of guanine and cytosine nucleotides , gram-positive bacteria are also classified into low G + C and high G + C gram-positive bacteria . <hl> The low G + C gram-positive bacteria have less than 50 % of guanine and cytosine nucleotides in their DNA . They include human pathogens , such as those that cause anthrax ( Bacillus anthracis ) , tetanus ( Clostridium tetani ) , and listeriosis ( Listeria monocytogenes ) . <hl> High G + C gram-positive bacteria , which have more than 50 % guanine and cytosine nucleotides in their DNA , include the bacteria that cause diphtheria ( Corynebacterium diphtheriae ) , tuberculosis ( Mycobacterium tuberculosis ) , and other diseases . <hl>", "hl_sentences": "Based on their prevalence of guanine and cytosine nucleotides , gram-positive bacteria are also classified into low G + C and high G + C gram-positive bacteria . High G + C gram-positive bacteria , which have more than 50 % guanine and cytosine nucleotides in their DNA , include the bacteria that cause diphtheria ( Corynebacterium diphtheriae ) , tuberculosis ( Mycobacterium tuberculosis ) , and other diseases .", "question": { "cloze_format": "___ is/are a bacterial specie that is classified as high G+C gram-positive.", "normal_format": "Which of the following bacterial species is classified as high G+C gram-positive?", "question_choices": [ "Corynebacterium diphtheriae", "Staphylococcus aureus", "Bacillus anthracis", "Streptococcus pneumonia" ], "question_id": "fs-id1172100813972", "question_text": "Which of the following bacterial species is classified as high G+C gram-positive?" }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 1, "ans_text": "B" }, "bloom": null, "hl_context": "<hl> On a phylogenetic tree ( see A Systematic Approach ) , the trunk or root of the tree represents a common ancient evolutionary ancestor , often called the last universal common ancestor ( LUCA ) , and the branches are its evolutionary descendants . <hl> <hl> Scientists consider the deeply branching bacteria , such as the genus Acetothermus , to be the first of these non-LUCA forms of life produced by evolution some 3.5 billion years ago . <hl> When placed on the phylogenetic tree , they stem from the common root of life , deep and close to the LUCA root — hence the name “ deeply branching ” ( Figure 4.24 ) .", "hl_sentences": "On a phylogenetic tree ( see A Systematic Approach ) , the trunk or root of the tree represents a common ancient evolutionary ancestor , often called the last universal common ancestor ( LUCA ) , and the branches are its evolutionary descendants . Scientists consider the deeply branching bacteria , such as the genus Acetothermus , to be the first of these non-LUCA forms of life produced by evolution some 3.5 billion years ago .", "question": { "cloze_format": "The term “deeply branching” refers to ___ .", "normal_format": "The term “deeply branching” refers to which of the following?", "question_choices": [ "the cellular shape of deeply branching bacteria", "the position in the evolutionary tree of deeply branching bacteria", "the ability of deeply branching bacteria to live in deep ocean waters", "the pattern of growth in culture of deeply branching bacteria" ], "question_id": "fs-id1172100906155", "question_text": "The term “deeply branching” refers to which of the following?" }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 1, "ans_text": "B" }, "bloom": null, "hl_context": "<hl> Finally , the deeply branching bacterium Deinococcus radiodurans belongs to a genus whose name is derived from a Greek word meaning terrible berry . <hl> <hl> Nicknamed “ Conan the Bacterium , ” D . radiodurans is considered a polyextremophile because of its ability to survive under the many different kinds of extreme conditions — extreme heat , drought , vacuum , acidity , and radiation . <hl> It owes its name to its ability to withstand doses of ionizing radiation that kill all other known bacteria ; this special ability is attributed to some unique mechanisms of DNA repair . 4.6 Archaea", "hl_sentences": "Finally , the deeply branching bacterium Deinococcus radiodurans belongs to a genus whose name is derived from a Greek word meaning terrible berry . Nicknamed “ Conan the Bacterium , ” D . radiodurans is considered a polyextremophile because of its ability to survive under the many different kinds of extreme conditions — extreme heat , drought , vacuum , acidity , and radiation .", "question": { "cloze_format": "The deeply branching bacteria that is considered a polyextremophile is the ___.", "normal_format": "Which of these deeply branching bacteria is considered a polyextremophile?", "question_choices": [ "Aquifex pyrophilus", "Deinococcus radiodurans", "Staphylococcus aureus", "Mycobacterium tuberculosis" ], "question_id": "fs-id1172100937701", "question_text": "Which of these deeply branching bacteria is considered a polyextremophile?" }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 3, "ans_text": "D" }, "bloom": null, "hl_context": "<hl> Like organisms in the domain Bacteria , organisms of the domain Archaea are all unicellular organisms . <hl> However , archaea differ structurally from bacteria in several significant ways , as discussed in Unique Characteristics of Prokaryotic Cells . To summarize : All living organisms are classified into three domains of life : Archaea , Bacteria , and Eukarya . In this chapter , we will focus on the domains Archaea and Bacteria . <hl> Archaea and bacteria are unicellular prokaryotic organisms . <hl> Unlike eukaryotes , they have no nuclei or any other membrane-bound organelles .", "hl_sentences": "Like organisms in the domain Bacteria , organisms of the domain Archaea are all unicellular organisms . Archaea and bacteria are unicellular prokaryotic organisms .", "question": { "cloze_format": "Archaea and Bacteria are most similar in terms of their ________.", "normal_format": "Archaea and Bacteria are most similar in terms of what?", "question_choices": [ "genetics", "cell wall structure", "ecology", "unicellular structure" ], "question_id": "fs-id1172102014650", "question_text": "Archaea and Bacteria are most similar in terms of their ________." }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 1, "ans_text": "B" }, "bloom": null, "hl_context": "The phylum Euryarchaeota includes several distinct classes . Species in the classes Methanobacteria , Methanococci , and Methanomicrobia represent Archaea that can be generally described as methanogens . <hl> Methanogens are unique in that they can reduce carbon dioxide in the presence of hydrogen , producing methane . <hl> <hl> They can live in the most extreme environments and can reproduce at temperatures varying from below freezing to boiling . <hl> Methanogens have been found in hot springs as well as deep under ice in Greenland . Methanogens also produce gases in ruminants and humans . Some scientists have even hypothesized that methanogen s may inhabit the planet Mars because the mixture of gases produced by methanogens resembles the makeup of the Martian atmosphere . 26 26 R . R . Britt “ Crater Critters : Where Mars Microbes Might Lurk . ” http://www.space.com/1880-crater-critters-mars-microbes-lurk.html . Accessed April 7 , 2015 .", "hl_sentences": "Methanogens are unique in that they can reduce carbon dioxide in the presence of hydrogen , producing methane . They can live in the most extreme environments and can reproduce at temperatures varying from below freezing to boiling .", "question": { "cloze_format": "Of archaea that produce methane, the true statement is that ___ .", "normal_format": "Which of the following is true of archaea that produce methane?", "question_choices": [ "They reduce carbon dioxide in the presence of nitrogen.", "They live in the most extreme environments.", "They are always anaerobes.", "They have been discovered on Mars." ], "question_id": "fs-id1172097276615", "question_text": "Which of the following is true of archaea that produce methane?" }, "references_are_paraphrase": 0 } ]
4
4.1 Prokaryote Habitats, Relationships, and Microbiomes Learning Objectives Identify and describe unique examples of prokaryotes in various habitats on earth Identify and describe symbiotic relationships Compare normal/commensal/resident microbiota to transient microbiota Explain how prokaryotes are classified Clinical Focus Part 1 Marsha, a 20-year-old university student, recently returned to the United States from a trip to Nigeria, where she had interned as a medical assistant for an organization working to improve access to laboratory services for tuberculosis testing. When she returned, Marsha began to feel fatigue, which she initially attributed to jet lag. However, the fatigue persisted, and Marsha soon began to experience other bothersome symptoms, such as occasional coughing, night sweats, loss of appetite, and a low-grade fever of 37.4 °C (99.3 °F). Marsha expected her symptoms would subside in a few days, but instead, they gradually became more severe. About two weeks after returning home, she coughed up some sputum and noticed that it contained blood and small whitish clumps resembling cottage cheese. Her fever spiked to 38.2 °C (100.8 °F), and she began feeling sharp pains in her chest when breathing deeply. Concerned that she seemed to be getting worse, Marsha scheduled an appointment with her physician. Could Marsha’s symptoms be related to her overseas travel, even several weeks after returning home? Jump to the next Clinical Focus box. All living organisms are classified into three domains of life: Archaea , Bacteria , and Eukarya . In this chapter, we will focus on the domains Archaea and Bacteria. Archaea and bacteria are unicellular prokaryotic organisms. Unlike eukaryotes, they have no nuclei or any other membrane-bound organelles. Prokaryote Habitats and Functions Prokaryotes are ubiquitous. They can be found everywhere on our planet, even in hot springs, in the Antarctic ice shield, and under extreme pressure two miles under water. One bacterium, Paracoccus denitrificans , has even been shown to survive when scientists removed it from its native environment (soil) and used a centrifuge to subject it to forces of gravity as strong as those found on the surface of Jupiter. Prokaryotes also are abundant on and within the human body. According to a report by National Institutes of Health, prokaryotes , especially bacteria, outnumber human cells 10:1. 1 More recent studies suggest the ratio could be closer to 1:1, but even that ratio means that there are a great number of bacteria within the human body. 2 Bacteria thrive in the human mouth, nasal cavity, throat, ears, gastrointestinal tract, and vagina. Large colonies of bacteria can be found on healthy human skin, especially in moist areas (armpits, navel, and areas behind ears). However, even drier areas of the skin are not free from bacteria. 1 Medical Press. “Mouth Bacteria Can Change Their Diet, Supercomputers Reveal.” August 12, 2014. http://medicalxpress.com/news/2014-08-mouth-bacteria-diet-supercomputers-reveal.html. Accessed February 24, 2015. 2 A. Abbott. “Scientists Bust Myth That Our Bodies Have More Bacteria Than Human Cells: Decades-Old Assumption about Microbiota Revisited.” Nature. http://www.nature.com/news/scientists-bust-myth-that-our-bodies-have-more-bacteria-than-human-cells-1.19136. Accessed June 3, 2016. The existence of prokaryotes is very important for the stability and thriving of ecosystems. For example, they are a necessary part of soil formation and stabilization processes through the breakdown of organic matter and development of biofilms. One gram of soil contains up to 10 billion microorganisms (most of them prokaryotic) belonging to about 1,000 species. Many species of bacteria use substances released from plant roots, such as acids and carbohydrates, as nutrients. The bacteria metabolize these plant substances and release the products of bacterial metabolism back to the soil, forming humus and thus increasing the soil’s fertility. In salty lakes such as the Dead Sea ( Figure 4.2 ), salt-loving halobacteria decompose dead brine shrimp and nourish young brine shrimp and flies with the products of bacterial metabolism. In addition to living in the ground and the water, prokaryotic microorganisms are abundant in the air, even high in the atmosphere. There may be up to 2,000 different kinds of bacteria in the air, similar to their diversity in the soil. Prokaryotes can be found everywhere on earth because they are extremely resilient and adaptable. They are often metabolically flexible, which means that they might easily switch from one energy source to another, depending on the availability of the sources, or from one metabolic pathway to another. For example, certain prokaryotic cyanobacteria can switch from a conventional type of lipid metabolism, which includes production of fatty aldehydes, to a different type of lipid metabolism that generates biofuel, such as fatty acids and wax esters. Groundwater bacteria store complex high-energy carbohydrates when grown in pure groundwater, but they metabolize these molecules when the groundwater is enriched with phosphates. Some bacteria get their energy by reducing sulfates into sulfides, but can switch to a different metabolic pathway when necessary, producing acids and free hydrogen ions. Prokaryotes perform functions vital to life on earth by capturing (or “fixing”) and recycling elements like carbon and nitrogen. Organisms such as animals require organic carbon to grow, but, unlike prokaryotes, they are unable to use inorganic carbon sources like carbon dioxide. Thus, animals rely on prokaryotes to convert carbon dioxide into organic carbon products that they can use. This process of converting carbon dioxide to organic carbon products is called carbon fixation . Plants and animals also rely heavily on prokaryotes for nitrogen fixation , the conversion of atmospheric nitrogen into ammonia, a compound that some plants can use to form many different biomolecules necessary to their survival. Bacteria in the genus Rhizobium , for example, are nitrogen-fixing bacteria; they live in the roots of legume plants such as clover, alfalfa, and peas ( Figure 4.3 ). Ammonia produced by Rhizobium helps these plants to survive by enabling them to make building blocks of nucleic acids. In turn, these plants may be eaten by animals—sustaining their growth and survival—or they may die, in which case the products of nitrogen fixation will enrich the soil and be used by other plants. Another positive function of prokaryotes is in cleaning up the environment. Recently, some researchers focused on the diversity and functions of prokaryotes in manmade environments. They found that some bacteria play a unique role in degrading toxic chemicals that pollute water and soil. 3 3 A.M. Kravetz “Unique Bacteria Fights Man-Made Chemical Waste.” 2012. http://www.livescience.com/25181-bacteria-strain-cleans-up-toxins-nsf-bts.html. Accessed March 9, 2015. Despite all of the positive and helpful roles prokaryotes play, some are human pathogens that may cause illness or infection when they enter the body. In addition, some bacteria can contaminate food, causing spoilage or foodborne illness, which makes them subjects of concern in food preparation and safety. Less than 1% of prokaryotes (all of them bacteria) are thought to be human pathogens, but collectively these species are responsible for a large number of the diseases that afflict humans. Besides pathogens, which have a direct impact on human health, prokaryotes also affect humans in many indirect ways. For example, prokaryotes are now thought to be key players in the processes of climate change . In recent years, as temperatures in the earth’s polar regions have risen, soil that was formerly frozen year-round (permafrost) has begun to thaw. Carbon trapped in the permafrost is gradually released and metabolized by prokaryotes. This produces massive amounts of carbon dioxide and methane, greenhouse gases that escape into the atmosphere and contribute to the greenhouse effect. Check Your Understanding In what types of environments can prokaryotes be found? Name some ways that plants and animals rely on prokaryotes. Symbiotic Relationships As we have learned, prokaryotic microorganisms can associate with plants and animals. Often, this association results in unique relationships between organisms. For example, bacteria living on the roots or leaves of a plant get nutrients from the plant and, in return, produce substances that protect the plant from pathogens. On the other hand, some bacteria are plant pathogens that use mechanisms of infection similar to bacterial pathogens of animals and humans. Prokaryotes live in a community , or a group of interacting populations of organisms. A population is a group of individual organisms belonging to the same biological species and limited to a certain geographic area. Populations can have cooperative interactions , which benefit the populations, or competitive interactions , in which one population competes with another for resources. The study of these interactions between microbial populations and their environment is called microbial ecology . Any interaction between different species that are associated with each other within a community is called symbiosis . Such interactions fall along a continuum between opposition and cooperation. Interactions in a symbiotic relationship may be beneficial or harmful, or have no effect on one or both of the species involved. Table 4.1 summarizes the main types of symbiotic interactions among prokaryotes. Types of Symbiotic Relationships Type Population A Population B Mutualism Benefitted Benefitted Amensalism Harmed Unaffected Commensalism Benefitted Unaffected Neutralism Unaffected Unaffected Parasitism Benefitted Harmed Table 4.1 When two species benefit from each other, the symbiosis is called mutualism (or syntropy, or crossfeeding). For example, humans have a mutualistic relationship with the bacterium Bacteroides thetaiotaomicron , which lives in the intestinal tract. Bacteroides thetaiotaomicron digests complex polysaccharide plant materials that human digestive enzymes cannot break down, converting them into monosaccharides that can be absorbed by human cells. Humans also have a mutualistic relationship with certain strains of Escherichia coli , another bacterium found in the gut. E. coli relies on intestinal contents for nutrients, and humans derive certain vitamins from E. coli, particularly vitamin K, which is required for the formation of blood clotting factors. (This is only true for some strains of E. coli , however. Other strains are pathogenic and do not have a mutualistic relationship with humans.) A type of symbiosis in which one population harms another but remains unaffected itself is called amensalism . In the case of bacteria, some amensalist species produce bactericidal substances that kill other species of bacteria. The microbiota of the skin is composed of a variety of bacterial species, including Staphylococcus epidermidis and Propionibacterium acnes . Although both species have the potential to cause infectious diseases when protective barriers are breached, they both produce a variety of antibacterial bacteriocins and bacteriocin-like compounds. S. epidermidis and P. acnes are unaffected by the bacteriocins and bacteriocin-like compounds they produce, but these compounds can target and kill other potential pathogens. In another type of symbiosis, called commensalism , one organism benefits while the other is unaffected. This occurs when the bacterium Staphylococcus epidermidis uses the dead cells of the human skin as nutrients. Billions of these bacteria live on our skin, but in most cases (especially when our immune system is healthy), we do not react to them in any way. S. epidermidis provides an excellent example of how the classifications of symbiotic relationships are not always distinct. One could also consider the symbiotic relationship of S. epidermidis with humans as mutualism. Humans provide a food source of dead skin cells to the bacterium, and in turn the production of bacteriocin can provide an defense against potential pathogens. If neither of the symbiotic organisms is affected in any way, we call this type of symbiosis neutralism . An example of neutralism is the coexistence of metabolically active (vegetating) bacteria and endospores (dormant, metabolically passive bacteria). For example, the bacterium Bacillus anthracis typically forms endospores in soil when conditions are unfavorable. If the soil is warmed and enriched with nutrients, some B. anthracis endospores germinate and remain in symbiosis with other species of endospores that have not germinated. A type of symbiosis in which one organism benefits while harming the other is called parasitism . The relationship between humans and many pathogenic prokaryotes can be characterized as parasitic because these organisms invade the body, producing toxic substances or infectious diseases that cause harm. Diseases such as tetanus, diphtheria, pertussis, tuberculosis, and leprosy all arise from interactions between bacteria and humans. Scientists have coined the term microbiome to refer to all prokaryotic and eukaryotic microorganisms and their genetic material that are associated with a certain organism or environment. Within the human microbiome , there are resident microbiota and transient microbiota . The resident microbiota consists of microorganisms that constantly live in or on our bodies. The term transient microbiota refers to microorganisms that are only temporarily found in the human body, and these may include pathogenic microorganisms. Hygiene and diet can alter both the resident and transient microbiota. The resident microbiota is amazingly diverse, not only in terms of the variety of species but also in terms of the preference of different microorganisms for different areas of the human body. For example, in the human mouth, there are thousands of commensal or mutualistic species of bacteria. Some of these bacteria prefer to inhabit the surface of the tongue, whereas others prefer the internal surface of the cheeks, and yet others prefer the front or back teeth or gums. The inner surface of the cheek has the least diverse microbiota because of its exposure to oxygen. By contrast, the crypts of the tongue and the spaces between teeth are two sites with limited oxygen exposure, so these sites have more diverse microbiota, including bacteria living in the absence of oxygen (e.g., Bacteroides , Fusobacterium ). Differences in the oral microbiota between randomly chosen human individuals are also significant. Studies have shown, for example, that the prevalence of such bacteria as Streptococcus , Haemophilus , Neisseria , and others was dramatically different when compared between individuals. 4 4 E.M. Bik et al. “Bacterial Diversity in the Oral Cavity of 10 Healthy Individuals.” The ISME Journal 4 no. 8 (2010):962–974. There are also significant differences between the microbiota of different sites of the same human body. The inner surface of the cheek has a predominance of Streptococcus , whereas in the throat, the palatine tonsil, and saliva, there are two to three times fewer Streptococcus , and several times more Fusobacterium . In the plaque removed from gums, the predominant bacteria belong to the genus Fusobacterium. However, in the intestine, both Streptococcus and Fusobacterium disappear, and the genus Bacteroides becomes predominant. Not only can the microbiota vary from one body site to another, the microbiome can also change over time within the same individual. Humans acquire their first inoculations of normal flora during natural birth and shortly after birth. Before birth, there is a rapid increase in the population of Lactobacillus spp. in the vagina, and this population serves as the first colonization of microbiota during natural birth. After birth, additional microbes are acquired from health-care providers, parents, other relatives, and individuals who come in contact with the baby. This process establishes a microbiome that will continue to evolve over the course of the individual’s life as new microbes colonize and are eliminated from the body. For example, it is estimated that within a 9-hour period, the microbiota of the small intestine can change so that half of the microbial inhabitants will be different. 5 The importance of the initial Lactobacillus colonization during vaginal child birth is highlighted by studies demonstrating a higher incidence of diseases in individuals born by cesarean section , compared to those born vaginally. Studies have shown that babies born vaginally are predominantly colonized by vaginal lactobacillus, whereas babies born by cesarean section are more frequently colonized by microbes of the normal skin microbiota, including common hospital-acquired pathogens. 5 C.C. Booijink et al. “High Temporal and Intra-Individual Variation Detected in the Human Ileal Microbiota.” Environmental Microbiology 12 no. 12 (2010):3213–3227. Throughout the body, resident microbiotas are important for human health because they occupy niches that might be otherwise taken by pathogenic microorganisms. For instance, Lactobacillus spp. are the dominant bacterial species of the normal vaginal microbiota for most women. lactobacillus produce lactic acid, contributing to the acidity of the vagina and inhibiting the growth of pathogenic yeasts. However, when the population of the resident microbiota is decreased for some reason (e.g., because of taking antibiotics), the pH of the vagina increases, making it a more favorable environment for the growth of yeasts such as Candida albicans . Antibiotic therapy can also disrupt the microbiota of the intestinal tract and respiratory tract, increasing the risk for secondary infections and/or promoting the long-term carriage and shedding of pathogens. Check Your Understanding Explain the difference between cooperative and competitive interactions in microbial communities. List the types of symbiosis and explain how each population is affected. Taxonomy and Systematics Assigning prokaryotes to a certain species is challenging. They do not reproduce sexually, so it is not possible to classify them according to the presence or absence of interbreeding. Also, they do not have many morphological features. Traditionally, the classification of prokaryotes was based on their shape, staining patterns, and biochemical or physiological differences. More recently, as technology has improved, the nucleotide sequences in genes have become an important criterion of microbial classification. In 1923, American microbiologist David Hendricks Bergey (1860–1937) published A Manual in Determinative Bacteriology. With this manual, he attempted to summarize the information about the kinds of bacteria known at that time, using Latin binomial classification. Bergey also included the morphological, physiological, and biochemical properties of these organisms. His manual has been updated multiple times to include newer bacteria and their properties. It is a great aid in bacterial taxonomy and methods of characterization of bacteria. A more recent sister publication, the five-volume Bergey’s Manual of Systematic Bacteriology , expands on Bergey’s original manual. It includes a large number of additional species, along with up-to-date descriptions of the taxonomy and biological properties of all named prokaryotic taxa. This publication incorporates the approved names of bacteria as determined by the List of Prokaryotic Names with Standing in Nomenclature (LPSN). Link to Learning The 7th edition (published in 1957) of Bergey’s Manual of Determinative Bacteriology is now available . More recent, updated editions are available in print. You can also access a searchable database of microbial reference strains, published by the American Type Culture Collection (ATCC). Classification by Staining Patterns According to their staining patterns , which depend on the properties of their cell walls, bacteria have traditionally been classified into gram-positive, gram-negative, and “atypical,” meaning neither gram-positive nor gram-negative. As explained in Staining Microscopic Specimens , gram-positive bacteria possess a thick peptidoglycan cell wall that retains the primary stain (crystal violet) during the decolorizing step; they remain purple after the gram-stain procedure because the crystal violet dominates the light red/pink color of the secondary counterstain, safranin. In contrast, gram-negative bacteria possess a thin peptidoglycan cell wall that does not prevent the crystal violet from washing away during the decolorizing step; therefore, they appear light red/pink after staining with the safranin. Bacteria that cannot be stained by the standard Gram stain procedure are called atypical bacteria . Included in the atypical category are species of Mycoplasma and Chlamydia . Rickettsia are also considered atypical because they are too small to be evaluated by the Gram stain. More recently, scientists have begun to further classify gram-negative and gram-positive bacteria. They have added a special group of deeply branching bacteria based on a combination of physiological, biochemical, and genetic features. They also now further classify gram-negative bacteria into Proteobacteria , Cytophaga-Flavobacterium-Bacteroides (CFB) , and spirochetes . The deeply branching bacteria are thought to be a very early evolutionary form of bacteria (see Deeply Branching Bacteria ). They live in hot, acidic, ultraviolet-light-exposed, and anaerobic (deprived of oxygen) conditions. Proteobacteria is a phylum of very diverse groups of gram-negative bacteria; it includes some important human pathogens (e.g., E. coli and Bordetella pertussis ). The CFB group of bacteria includes components of the normal human gut microbiota, like Bacteroides . The spirochetes are spiral-shaped bacteria and include the pathogen Treponema pallidum , which causes syphilis. We will characterize these groups of bacteria in more detail later in the chapter. Based on their prevalence of guanine and cytosine nucleotides, gram-positive bacteria are also classified into low G+C and high G+C gram-positive bacteria . The low G+C gram-positive bacteria have less than 50% of guanine and cytosine nucleotides in their DNA. They include human pathogens, such as those that cause anthrax ( Bacillus anthracis ), tetanus ( Clostridium tetani ), and listeriosis ( Listeria monocytogenes ). High G+C gram-positive bacteria, which have more than 50% guanine and cytosine nucleotides in their DNA, include the bacteria that cause diphtheria ( Corynebacterium diphtheriae ), tuberculosis ( Mycobacterium tuberculosis ), and other diseases. The classifications of prokaryotes are constantly changing as new species are being discovered. We will describe them in more detail, along with the diseases they cause, in later sections and chapters. Check Your Understanding How do scientists classify prokaryotes? Micro Connections Human Microbiome Project The Human Microbiome Project was launched by the National Institutes of Health (NIH) in 2008. One main goal of the project is to create a large repository of the gene sequences of important microbes found in humans, helping biologists and clinicians understand the dynamics of the human microbiome and the relationship between the human microbiota and diseases. A network of labs working together has been compiling the data from swabs of several areas of the skin, gut, and mouth from hundreds of individuals. One of the challenges in understanding the human microbiome has been the difficulty of culturing many of the microbes that inhabit the human body. It has been estimated that we are only able to culture 1% of the bacteria in nature and that we are unable to grow the remaining 99%. To address this challenge, researchers have used metagenomic analysis , which studies genetic material harvested directly from microbial communities, as opposed to that of individual species grown in a culture. This allows researchers to study the genetic material of all microbes in the microbiome, rather than just those that can be cultured. 6 6 National Institutes of Health. “Human Microbiome Project. Overview.” http://commonfund.nih.gov/hmp/overview. Accessed June 7, 2016. One important achievement of the Human Microbiome Project is establishing the first reference database on microorganisms living in and on the human body. Many of the microbes in the microbiome are beneficial, but some are not. It was found, somewhat unexpectedly, that all of us have some serious microbial pathogens in our microbiota. For example, the conjunctiva of the human eye contains 24 genera of bacteria and numerous pathogenic species. 7 A healthy human mouth contains a number of species of the genus Streptococcus , including pathogenic species S. pyogenes and S. pneumoniae . 8 This raises the question of why certain prokaryotic organisms exist commensally in certain individuals but act as deadly pathogens in others. Also unexpected was the number of organisms that had never been cultured. For example, in one metagenomic study of the human gut microbiota, 174 new species of bacteria were identified. 9 7 Q. Dong et al. “Diversity of Bacteria at Healthy Human Conjunctiva.” Investigative Ophthalmology & Visual Science 52 no. 8 (2011):5408–5413. 8 F.E. Dewhirst et al. “The Human Oral Microbiome.” Journal of Bacteriology 192 no. 19 (2010):5002–5017. 9 J.C. Lagier et al. “Microbial Culturomics: Paradigm Shift in the Human Gut Microbiome Study.” Clinical Microbiology and Infection 18 no. 12 (2012):1185–1193. Another goal for the near future is to characterize the human microbiota in patients with different diseases and to find out whether there are any relationships between the contents of an individual’s microbiota and risk for or susceptibility to specific diseases. Analyzing the microbiome in a person with a specific disease may reveal new ways to fight diseases. 4.2 Proteobacteria Learning Objectives Describe the unique features of each class within the phylum Proteobacteria: Alphaproteobacteria, Betaproteobacteria, Gammaproteobacteria, Deltaproteobacteria, and Epsilonproteobacteria Give an example of a bacterium in each class of Proteobacteria In 1987, the American microbiologist Carl Woese (1928–2012) suggested that a large and diverse group of bacteria that he called “purple bacteria and their relatives” should be defined as a separate phylum within the domain Bacteria based on the similarity of the nucleotide sequences in their genome. 10 This phylum of gram-negative bacteria subsequently received the name Proteobacteria . It includes many bacteria that are part of the normal human microbiota as well as many pathogens. The Proteobacteria are further divided into five classes: Alphaproteobacteria, Betaproteobacteria, Gammaproteobacteria, Deltaproteobacteria, and Epsilonproteobacteria ( Appendix D ). 10 C.R. Woese. “Bacterial Evolution.” Microbiological Review 51 no. 2 (1987):221–271. Alphaproteobacteria The first class of Proteobacteria is the Alphaproteobacteria , many of which are obligate or facultative intracellular bacteria. Some species are characterized as oligotroph s, organisms capable of living in low-nutrient environments such as deep oceanic sediments, glacial ice, or deep undersurface soil. Among the Alphaproteobacteria are rickettsias, obligate intracellular pathogen s, that require part of their life cycle to occur inside other cells called host cells. When not growing inside a host cell, Rickettsia are metabolically inactive outside the host cell. They cannot synthesize their own adenosine triphosphate (ATP), and, therefore, rely on cells for their energy needs. Rickettsia spp. include a number of serious human pathogens. For example, R. rickettsii causes Rocky Mountain spotted fever , a life-threatening form of meningoencephalitis (inflammation of the membranes that wrap the brain). R. rickettsii infects ticks and can be transmitted to humans via a bite from an infected tick ( Figure 4.4 ). Another species of Rickettsia , R. prowazekii , is spread by lice. It causes epidemic typhus , a severe infectious disease common during warfare and mass migrations of people. R. prowazekii infects human endothelium cells, causing inflammation of the inner lining of blood vessels, high fever, abdominal pain, and sometimes delirium. A relative, R. typhi , causes a less severe disease known as murine or endemic typhus, which is still observed in the southwestern United States during warm seasons. Table 4.2 summarizes the characteristics of important genera of Alphaproteobacteria. C. trachomatis is a human pathogen that causes trachoma , a disease of the eyes, often leading to blindness. C. trachomatis also causes the sexually transmitted disease lymphogranuloma venereum (LGV). This disease is often mildly symptomatic, manifesting as regional lymph node swelling, or it may be asymptomatic, but it is extremely contagious and is common on college campuses. Class Alphaproteobacteria Genus Microscopic Morphology Unique Characteristics Agrobacterium Gram-negative bacillus Plant pathogen; one species, A. tumefaciens , causes tumors in plants Bartonella Gram-negative, pleomorphic, flagellated coccobacillus Facultative intracellular bacteria, transmitted by lice and fleas, cause trench fever and cat scratch disease in humans Brucella Gram-negative, small, flagellated coccobacillus Facultative intracellular bacteria, transmitted by contaminated milk from infected cows, cause brucellosis in cattle and humans Caulobacter Gram-negative bacillus Used in studies on cellular adaptation and differentiation because of its peculiar life cycle (during cell division, forms “swarm” cells and “stalked” cells) Coxiella Small, gram-negative bacillus Obligatory intracellular bacteria; cause Q fever; potential for use as biological weapon Ehrlichia Very small, gram-negative, coccoid or ovoid bacteria Obligatory intracellular bacteria; can be transported from cell to cell; transmitted by ticks; cause ehrlichiosis (destruction of white blood cells and inflammation) in humans and dogs Hyphomicrobium Gram-negative bacilli; grows from a stalk Similar to Caulobacter Methylocystis Gram-negative, coccoid or short bacilli Nitrogen-fixing aerobic bacteria Rhizobium Gram-negative, rectangular bacilli with rounded ends forming clusters Nitrogen-fixing bacteria that live in soil and form symbiotic relationship with roots of legumes (e.g., clover, alfalfa, and beans) Rickettsia Gram-negative, highly pleomorphic bacteria (may be cocci, rods, or threads) Obligate intracellular bacteria; transmitted by ticks; may cause Rocky Mountain spotted fever and typhus Table 4.2 Check Your Understanding What is a common characteristic among the human pathogenic Alphaproteobacteria? Betaproteobacteria Betaproteobacteria are a diverse group of bacteria. The different bacterial species within this group utilize a wide range of metabolic strategies and can survive in a range of environments. Some genera include species that are human pathogens, able to cause severe, sometimes life-threatening disease. The genus Neisseria , for example, includes the bacteria N. gonorrhoeae, the causative agent of the STI gonorrhea , and N. meningitides , the causative agent of bacterial meningitis . Neisseria are cocci that live on mucosal surfaces of the human body. They are fastidious, or difficult to culture, and they require high levels of moisture, nutrient supplements, and carbon dioxide. Also, Neisseria are microaerophilic, meaning that they require low levels of oxygen. For optimal growth and for the purposes of identification, Neisseria spp. are grown on chocolate agar (i.e., agar supplemented by partially hemolyzed red blood cells). Their characteristic pattern of growth in culture is diplococcal: pairs of cells resembling coffee beans ( Figure 4.5 ). The pathogen responsible for pertussis ( whooping cough ) is also a member of Betaproteobacteria. The bacterium Bordetella pertussis , from the order Burkholderiales , produces several toxins that paralyze the movement of cilia in the human respiratory tract and directly damage cells of the respiratory tract, causing a severe cough. Table 4.3 summarizes the characteristics of important genera of Betaproteobacteria. Class Betaproteobacteria Example Genus Microscopic Morphology Unique Characteristics Bordetella A small, gram-negative coccobacillus Aerobic, very fastidious; B. pertussis causes pertussis (whooping cough) Burkholderia Gram-negative bacillus Aerobic, aquatic, cause diseases in horses and humans (especially patients with cystic fibrosis); agents of nosocomial infections Leptothrix Gram-negative, sheathed, filamentous bacillus Aquatic; oxidize iron and manganese; can live in wastewater treatment plants and clog pipes Neisseria Gram-negative, coffee bean-shaped coccus forming pairs Require moisture and high concentration of carbon dioxide; oxidase positive, grow on chocolate agar; pathogenic species cause gonorrhea and meningitis Thiobacillus Gram-negative bacillus Thermophilic, acidophilic, strictly aerobic bacteria; oxidize iron and sulfur Table 4.3 Check Your Understanding Why are Neisseria classified as microaerophilic? Clinical Focus Part 2 When Marsha finally went to the doctor’s office, the physician listened to her breathing through a stethoscope. He heard some crepitation (a crackling sound) in her lungs, so he ordered a chest radiograph and asked the nurse to collect a sputum sample for microbiological evaluation and cytology. The radiologic evaluation found cavities, opacities, and a particular pattern of distribution of abnormal material ( Figure 4.6 ). What are some possible diseases that could be responsible for Marsha’s radiograph results? Jump to the next Clinical Focus box. Go back to the previous Clinical Focus box. Gammaproteobacteria The most diverse class of gram-negative bacteria is Gammaproteobacteria , and it includes a number of human pathogens. For example, a large and diverse family, Pseudomonaceae , includes the genus Pseudomonas . Within this genus is the species P. aeruginosa , a pathogen responsible for diverse infections in various regions of the body. P. aeruginosa is a strictly aerobic, nonfermenting, highly motile bacterium. It often infects wounds and burns, can be the cause of chronic urinary tract infections, and can be an important cause of respiratory infections in patients with cystic fibrosis or patients on mechanical ventilators. Infections by P. aeruginosa are often difficult to treat because the bacterium is resistant to many antibiotics and has a remarkable ability to form biofilms. Other representatives of Pseudomonas include the fluorescent (glowing) bacterium P. fluorescens and the soil bacteria P. putida , which is known for its ability to degrade xenobiotics (substances not naturally produced or found in living organisms). The Pasteurellaceae also includes several clinically relevant genera and species. This family includes several bacteria that are human and/or animal pathogens. For example, Pasteurella haemolytica causes severe pneumonia in sheep and goats. P. multocida is a species that can be transmitted from animals to humans through bites, causing infections of the skin and deeper tissues. The genus Haemophilus contains two human pathogens, H. influenzae and H. ducreyi . Despite its name, H. influenzae does not cause influenza (which is a viral disease). H. influenzae can cause both upper and lower respiratory tract infections, including sinusitis, bronchitis, ear infections, and pneumonia. Before the development of effective vaccination, strains of H. influenzae were a leading cause of more invasive diseases, like meningitis in children. H. ducreyi causes the STI known as chancroid . The order Vibrionales includes the human pathogen Vibrio cholerae . This comma-shaped aquatic bacterium thrives in highly alkaline environments like shallow lagoons and sea ports. A toxin produced by V. cholerae causes hypersecretion of electrolytes and water in the large intestine, leading to profuse watery diarrhea and dehydration. V. parahaemolyticus is also a cause of gastrointestinal disease in humans, whereas V. vulnificus causes serious and potentially life-threatening cellulitis (infection of the skin and deeper tissues) and blood-borne infections. Another representative of Vibrionales, Aliivibrio fischeri , engages in a symbiotic relationship with squid. The squid provides nutrients for the bacteria to grow and the bacteria produce bioluminescence that protects the squid from predators ( Figure 4.7 ). The genus Legionella also belongs to the Gammaproteobacteria. L. pneumophila, the pathogen responsible for Legionnaires disease , is an aquatic bacterium that tends to inhabit pools of warm water, such as those found in the tanks of air conditioning units in large buildings ( Figure 4.8 ). Because the bacteria can spread in aerosols, outbreaks of Legionnaires disease often affect residents of a building in which the water has become contaminated with Legionella. In fact, these bacteria derive their name from the first known outbreak of Legionnaires disease, which occurred in a hotel hosting an American Legion veterans’ association convention in Philadelphia in 1976. Enterobacteriaceae is a large family of enteric (intestinal) bacteria belonging to the Gammaproteobacteria . They are facultative anaerobes and are able to ferment carbohydrates. Within this family, microbiologists recognize two distinct categories. The first category is called the coliforms, after its prototypical bacterium species, Escherichia coli . Coliforms are able to ferment lactose completely (i.e., with the production of acid and gas). The second category, noncoliforms , either cannot ferment lactose or can only ferment it incompletely (producing either acid or gas, but not both). The noncoliforms include some notable human pathogens, such as Salmonella spp ., Shigella spp ., and Yersinia pestis . E. coli has been perhaps the most studied bacterium since it was first described in 1886 by Theodor Escherich (1857–1911). Many strains of E. coli are in mutualistic relationships with humans. However, some strains produce a potentially deadly toxin called Shiga toxin. Shiga toxin is one of the most potent bacterial toxins identified. Upon entering target cells, Shiga toxin interacts with ribosomes, stopping protein synthesis. Lack of protein synthesis leads to cellular death and hemorrhagic colitis, characterized by inflammation of intestinal tract and bloody diarrhea. In the most severe cases, patients can develop a deadly hemolytic uremic syndrome. Other E. coli strains may cause traveler’s diarrhea, a less severe but very widespread disease. The genus Salmonella , which belongs to the noncoliform group of Enterobacteriaceae , is interesting in that there is still no consensus about how many species it includes. Scientists have reclassified many of the groups they once thought to be species as serotypes (also called serovars ), which are strains or variations of the same species of bacteria. Their classification is based on patterns of reactivity by animal antisera against molecules on the surface of the bacterial cells. A number of serotypes of Salmonella can cause salmonellosis , characterized by inflammation of the small and the large intestine, accompanied by fever, vomiting, and diarrhea. The species S. enterobacterica (serovar typhi ) causes typhoid fever , with symptoms including fever, abdominal pain, and skin rashes ( Figure 4.9 ). Table 4.4 summarizes the characteristics of important genera of Gammaproteobacteria. Class Gammaproteobacteria Example Genus Microscopic Morphology Unique Characteristics Beggiatoa Gram-negative bacteria; disc-shaped or cylindrical Aquatic, live in water with high content of hydrogen disulfide; can cause problems for sewage treatment Enterobacter Gram-negative bacillus Facultative anaerobe; cause urinary and respiratory tract infections in hospitalized patients; implicated in the pathogenesis of obesity Erwinia Gram-negative bacillus Plant pathogen causing leaf spots and discoloration; may digest cellulose; prefer relatively low temperatures (25–30 °C) Escherichia Gram-negative bacillus Facultative anaerobe; inhabit the gastrointestinal tract of warm-blooded animals; some strains are mutualists, producing vitamin K; others, like serotype E. coli O157:H7, are pathogens; E. coli has been a model organism for many studies in genetics and molecular biology Hemophilus Gram-negative bacillus Pleomorphic, may appear as coccobacillus, aerobe, or facultative anaerobe; grow on blood agar; pathogenic species can cause respiratory infections, chancroid, and other diseases Klebsiella Gram-negative bacillus; appears rounder and thicker than other members of Enterobacteriaceae Facultative anaerobe, encapsulated, nonmotile; pathogenic species may cause pneumonia, especially in people with alcoholism Legionella Gram-negative bacillus Fastidious, grow on charcoal-buffered yeast extract; L. pneumophila causes Legionnaires disease Methylomonas Gram-negative bacillus Use methane as source of carbon and energy Proteus Gram-negative bacillus (pleomorphic) Common inhabitants of the human gastrointestinal tract; motile; produce urease; opportunistic pathogens; may cause urinary tract infections and sepsis Pseudomonas Gram-negative bacillus Aerobic; versatile; produce yellow and blue pigments, making them appear green in culture; opportunistic, antibiotic-resistant pathogens may cause wound infections, hospital-acquired infections, and secondary infections in patients with cystic fibrosis Serratia Gram-negative bacillus Motile; may produce red pigment; opportunistic pathogens responsible for a large number of hospital-acquired infections Shigella Gram-negative bacillus Nonmotile; dangerously pathogenic; produce Shiga toxin, which can destroy cells of the gastrointestinal tract; can cause dysentery Vibrio Gram-negative, comma- or curved rod-shaped bacteria Inhabit seawater; flagellated, motile; may produce toxin that causes hypersecretion of water and electrolytes in the gastrointestinal tract; some species may cause serious wound infections Yersinia Gram-negative bacillus Carried by rodents; human pathogens; Y. pestis causes bubonic plague and pneumonic plague; Y. enterocolitica can be a pathogen causing diarrhea in humans Table 4.4 Check Your Understanding List two families of Gammaproteobacteria. Deltaproteobacteria The Deltaproteobacteria is a small class of gram-negative Proteobacteria that includes sulfate-reducing bacteria (SRBs), so named because they use sulfate as the final electron acceptor in the electron transport chain. Few SRBs are pathogenic. However, the SRB Desulfovibrio orale is associated with periodontal disease (disease of the gums). Deltaproteobacteria also includes the genus Bdellovibrio , species of which are parasites of other gram-negative bacteria. Bdellovibrio invades the cells of the host bacterium, positioning itself in the periplasm, the space between the plasma membrane and the cell wall, feeding on the host’s proteins and polysaccharides. The infection is lethal for the host cells. Another type of Deltaproteobacteria, myxobacteria , lives in the soil, scavenging inorganic compounds. Motile and highly social, they interact with other bacteria within and outside their own group. They can form multicellular, macroscopic “ fruiting bodies ” ( Figure 4.10 ), structures that are still being studied by biologists and bacterial ecologists. 11 These bacteria can also form metabolically inactive myxospores . 11 H. Reichenbach. “Myxobacteria, Producers of Novel Bioactive Substances.” Journal of Industrial Microbiology & Biotechnology 27 no. 3 (2001):149–156. Table 4.5 summarizes the characteristics of several important genera of Deltaproteobacteria. Class Deltaproteobacteria Genus Microscopic Morphology Unique characteristics Bdellovibrio Gram-negative, comma-shaped rod Obligate aerobes; motile; parasitic (infecting other bacteria) Desulfovibrio (formerly Desufuromonas ) Gram-negative, comma-shaped rod Reduce sulfur; can be used for removal of toxic and radioactive waste Myxobacterium Gram-negative, coccoid bacteria forming colonies (swarms) Live in soil; can move by gliding; used as a model organism for studies of intercellular communication (signaling) Table 4.5 Check Your Understanding What type of Deltaproteobacteria forms fruiting bodies? Epsilonproteobacteria The smallest class of Proteobacteria is Epsilonproteobacteria , which are gram-negative microaerophilic bacteria (meaning they only require small amounts of oxygen in their environment). Two clinically relevant genera of Epsilonproteobacteria are Campylobacter and Helicobacter , both of which include human pathogens. Campylobacter can cause food poisoning that manifests as severe enteritis (inflammation in the small intestine). This condition, caused by the species C. jejuni , is rather common in developed countries, usually because of eating contaminated poultry products. Chickens often harbor C. jejuni in their gastrointestinal tract and feces, and their meat can become contaminated during processing. Within the genus Helicobacter, the helical, flagellated bacterium H. pylori has been identified as a beneficial member of the stomach microbiota, but it is also the most common cause of chronic gastritis and ulcers of the stomach and duodenum ( Figure 4.11 ). Studies have also shown that H. pylori is linked to stomach cancer. 12 H. pylori is somewhat unusual in its ability to survive in the highly acidic environment of the stomach. It produces urease and other enzymes that modify its environment to make it less acidic. 12 S. Suerbaum, P. Michetti. “ Helicobacter pylori infection.” New England Journal of Medicine 347 no. 15 (2002):1175–1186. Table 4.6 summarizes the characteristics of the most clinically relevant genera of Epsilonproteobacteria. Class Epsilonproteobacteria Example Genus Microscopic Morphology Unique Characteristics Campylobacter Gram-negative, spiral-shaped rod Aerobic (microaerophilic); often infects chickens; may infect humans via undercooked meat, causing severe enteritis Helicobacter Gram-negative, spiral-shaped rod Aerobic (microaerophilic) bacterium; can damage the inner lining of the stomach, causing chronic gastritis, peptic ulcers, and stomach cancer Table 4.6 Check Your Understanding Name two Epsilonproteobacteria that cause gastrointestinal disorders. 4.3 Nonproteobacteria Gram-Negative Bacteria and Phototrophic Bacteria Learning Objectives Describe the unique features of nonproteobacteria gram-negative bacteria Give an example of a nonproteobacteria bacterium in each category Describe the unique features of phototrophic bacteria Identify phototrophic bacteria The majority of the gram-negative bacteria belong to the phylum Proteobacteria, discussed in the previous section. Those that do not are called the nonproteobacteria . In this section, we will describe four classes of gram-negative nonproteobacteria: Chlamydia , the spirochetes, the CFB group, and the Planctomycetes. A diverse group of phototrophic bacteria that includes Proteobacteria and nonproteobacteria will be discussed at the end of this section. Chlamydia Chlamydia is another taxon of the Alphaproteobacteria. Members of this genus are gram-negative, obligate intracellular pathogens that are extremely resistant to the cellular defenses, giving them the ability to spread from host to host rapidly via elementary bodies. The metabolically and reproductively inactive elementary bodies are the endospore-like form of intracellular bacteria that enter an epithelial cell, where they become active. Figure 4.12 illustrates the life cycle of Chlamydia . Spirochetes Spirochetes are characterized by their long (up to 250 μm), spiral-shaped bodies. Most spirochetes are also very thin, which makes it difficult to examine gram-stained preparations under a conventional brightfield microscope. Darkfield fluorescent microscopy is typically used instead. Spirochetes are also difficult or even impossible to culture. They are highly motile, using their axial filament to propel themselves. The axial filament is similar to a flagellum, but it wraps around the cell and runs inside the cell body of a spirochete in the periplasmic space between the outer membrane and the plasma membrane ( Figure 4.13 ). Several genera of spirochetes include human pathogens. For example, the genus Treponema includes a species T. pallidum , which is further classified into four subspecies: T. pallidum pallidum , T. pallidum pertenue, T. pallidum carateum, and T. pallidum endemicum . The subspecies T. pallidum pallidum causes the sexually transmitted infection known as syphilis , the third most prevalent sexually transmitted bacterial infection in the United States, after chlamydia and gonorrhea. The other subspecies of T. pallidum cause tropical infectious diseases of the skin, bones, and joints. Another genus of spirochete, Borrelia , contains a number of pathogenic species. B. burgdorferi causes Lyme disease , which is transmitted by several genera of ticks (notably Ixodes and Amblyomma ) and often produces a “bull’s eye” rash, fever, fatigue, and, sometimes, debilitating arthritis. B. recurrens causes a condition known as relapsing fever. Appendix D lists the genera, species, and related diseases for spirochetes. Check Your Understanding Why do scientists typically use darkfield fluorescent microscopy to visualize spirochetes? Cytophaga , Fusobacterium , and Bacteroides The gram-negative nonproteobacteria of the genera Cytophaga , Fusobacterium , and Bacteroides are classified together as a phylum and called the CFB group . Although they are phylogenetically diverse, bacteria of the CFB group share some similarities in the sequence of nucleotides in their DNA. They are rod-shaped bacteria adapted to anaerobic environments, such as the tissue of the gums, gut, and rumen of ruminating animals. CFB bacteria are avid fermenters, able to process cellulose in rumen, thus enabling ruminant animals to obtain carbon and energy from grazing. Cytophaga are motile aquatic bacteria that glide. Fusobacteria inhabit the human mouth and may cause severe infectious diseases. The largest genus of the CFB group is Bacteroides , which includes dozens of species that are prevalent inhabitants of the human large intestine, making up about 30% of the entire gut microbiome ( Figure 4.14 ). One gram of human feces contains up to 100 billion Bacteroides cells. Most Bacteroides are mutualistic. They benefit from nutrients they find in the gut, and humans benefit from their ability to prevent pathogens from colonizing the large intestine. Indeed, when populations of Bacteroides are reduced in the gut—as often occurs when a patient takes antibiotics—the gut becomes a more favorable environment for pathogenic bacteria and fungi, which can cause secondary infections. Only a few species of Bacteroides are pathogenic. B. melaninogenicus , for example, can cause wound infections in patients with weakened immune systems. Check Your Understanding Why are Cytophaga , Fusobacterium , and Bacteroides classified together as the CFB group? Planctomycetes The Planctomycetes are found in aquatic environments, inhabiting freshwater, saltwater, and brackish water. Planctomycetes are unusual in that they reproduce by budding, meaning that instead of one maternal cell splitting into two equal daughter cells in the process of binary fission, the mother cell forms a bud that detaches from the mother cell and lives as an independent cell. These so-called swarmer cells are motile and not attached to a surface. However, they will soon differentiate into sessile (immobile) cells with an appendage called a holdfast that allows them to attach to surfaces in the water ( Figure 4.15 ). Only the sessile cells are able to reproduce. Table 4.7 summarizes the characteristics of some of the most clinically relevant genera of nonproteobacteria. Nonproteobacteria Example Genus Microscopic Morphology Unique Characteristics Chlamydia Gram-negative, coccoid or ovoid bacterium Obligatory intracellular bacteria; some cause chlamydia, trachoma, and pneumonia Bacteroides Gram-negative bacillus Obligate anaerobic bacteria; abundant in the human gastrointestinal tract; usually mutualistic, although some species are opportunistic pathogens Cytophaga Gram-negative bacillus Motile by gliding; live in soil or water; decompose cellulose; may cause disease in fish Fusobacterium Gram-negative bacillus with pointed ends Anaerobic; form; biofilms; some species cause disease in humans (periodontitis, ulcers) Leptospira Spiral-shaped bacterium (spirochetes); gram negative-like (better viewed by darkfield microscopy); very thin Aerobic, abundant in shallow water reservoirs; infect rodents and domestic animals; can be transmitted to humans by infected animals’ urine; may cause severe disease Borrelia Gram-negative-like spirochete; very thin; better viewed by darkfield microscopy B. burgdorferi causes Lyme disease and B. recurrens causes relapsing fever Treponema Gram-negative-like spirochete; very thin; better viewed by darkfield microscopy Motile; do not grow in culture; T. pallidum (subspecies T. pallidum pallidum ) causes syphilis Table 4.7 Check Your Understanding How do Planctomycetes reproduce? Phototrophic Bacteria The phototrophic bacteria are a large and diverse category of bacteria that do not represent a taxon but, rather, a group of bacteria that use sunlight as their primary source of energy. This group contains both Proteobacteria and nonproteobacteria . They use solar energy to synthesize ATP through photosynthesis . When they produce oxygen, they perform oxygenic photosynthesis. When they do not produce oxygen, they perform anoxygenic photosynthesis. With the exception of some cyanobacteria, the majority of phototrophic bacteria perform anoxygenic photosynthesis. One large group of phototrophic bacteria includes the purple or green bacteria that perform photosynthesis with the help of bacteriochlorophylls , which are green, purple, or blue pigments similar to chlorophyll in plants. Some of these bacteria have a varying amount of red or orange pigments called carotenoids . Their color varies from orange to red to purple to green ( Figure 4.16 ), and they are able to absorb light of various wavelengths. Traditionally, these bacteria are classified into sulfur and nonsulfur bacteria ; they are further differentiated by color. The sulfur bacteria perform anoxygenic photosynthesis, using sulfites as electron donors and releasing free elemental sulfur. Nonsulfur bacteria use organic substrates, such as succinate and malate, as donors of electrons. The purple sulfur bacteria oxidize hydrogen sulfide into elemental sulfur and sulfuric acid and get their purple color from the pigments bacteriochlorophylls and carotenoids. Bacteria of the genus Chromatium are purple sulfur Gammaproteobacteria . These microorganisms are strict anaerobes and live in water. They use carbon dioxide as their only source of carbon, but their survival and growth are possible only in the presence of sulfites, which they use as electron donors. Chromatium has been used as a model for studies of bacterial photosynthesis since the 1950s. 13 13 R.C. Fuller et al. “Carbon Metabolism in Chromatium .” Journal of Biological Chemistry 236 (1961):2140–2149. The green sulfur bacteria use sulfide for oxidation and produce large amounts of green bacteriochlorophyll. The genus Chlorobium is a green sulfur bacterium that is implicated in climate change because it produces methane, a greenhouse gas. These bacteria use at least four types of chlorophyll for photosynthesis . The most prevalent of these, bacteriochlorophyll, is stored in special vesicle-like organelles called chlorosomes . Purple nonsulfur bacteria are similar to purple sulfur bacteria, except that they use hydrogen rather than hydrogen sulfide for oxidation. Among the purple nonsulfur bacteria is the genus Rhodospirillum . These microorganisms are facultative anaerobes, which are actually pink rather than purple, and can metabolize (“fix”) nitrogen. They may be valuable in the field of biotechnology because of their potential ability to produce biological plastic and hydrogen fuel. 14 14 T.T. Selao et al. “Comparative Proteomic Studies in Rhodospirillum rubrum Grown Under Different Nitrogen Conditions.” Journal of Proteome Research 7 no. 8 (2008):3267–3275. The green nonsulfur bacteria are similar to green sulfur bacteria but they use substrates other than sulfides for oxidation. Chloroflexus is an example of a green nonsulfur bacterium. It often has an orange color when it grows in the dark, but it becomes green when it grows in sunlight. It stores bacteriochlorophyll in chlorosomes, similar to Chlorobium , and performs anoxygenic photosynthesis , using organic sulfites (low concentrations) or molecular hydrogen as electron donors, so it can survive in the dark if oxygen is available. Chloroflexus does not have flagella but can glide, like Cytophaga . It grows at a wide range of temperatures, from 35 °C to 70 °C, thus can be thermophilic. Another large, diverse group of phototrophic bacteria compose the phylum Cyanobacteria ; they get their blue-green color from the chlorophyll contained in their cells ( Figure 4.17 ). Species of this group perform oxygenic photosynthesis, producing megatons of gaseous oxygen. Scientists hypothesize that cyanobacteria played a critical role in the change of our planet’s anoxic atmosphere 1–2 billion years ago to the oxygen-rich environment we have today. 15 15 A. De los Rios et al. “Ultrastructural and Genetic Characteristics of Endolithic Cyanobacterial Biofilms Colonizing Antarctic Granite Rocks.” FEMS Microbiology Ecology 59 no. 2 (2007):386–395. Cyanobacteria have other remarkable properties. Amazingly adaptable, they thrive in many habitats, including marine and freshwater environments, soil, and even rocks. They can live at a wide range of temperatures, even in the extreme temperatures of the Antarctic. They can live as unicellular organisms or in colonies, and they can be filamentous, forming sheaths or biofilms. Many of them fix nitrogen, converting molecular nitrogen into nitrites and nitrates that other bacteria, plants, and animals can use. The reactions of nitrogen fixation occur in specialized cells called heterocysts . Photosynthesis in Cyanobacteria is oxygenic, using the same type of chlorophyll a found in plants and algae as the primary photosynthetic pigment. Cyanobacteria also use phycocyanin and cyanophycin , two secondary photosynthetic pigments that give them their characteristic blue color. They are located in special organelles called phycobilisomes and in folds of the cellular membrane called thylakoids , which are remarkably similar to the photosynthetic apparatus of plants. Scientists hypothesize that plants originated from endosymbiosis of ancestral eukaryotic cells and ancestral photosynthetic bacteria. 16 Cyanobacteria are also an interesting object of research in biochemistry, 17 with studies investigating their potential as biosorbents 18 and products of human nutrition. 19 16 T. Cavalier-Smith. “Membrane Heredity and Early Chloroplast Evolution.” Trends in Plant Science 5 no. 4 (2000):174–182. 17 S. Zhang, D.A. Bryant. “The Tricarboxylic Acid Cycle in Cyanobacteria.” Science 334 no. 6062 (2011):1551–1553. 18 A. Cain et al. “Cyanobacteria as a Biosorbent for Mercuric Ion.” Bioresource Technology 99 no. 14 (2008):6578–6586. 19 C.S. Ku et al. “Edible Blue-Green Algae Reduce the Production of Pro-Inflammatory Cytokines by Inhibiting NF-κB Pathway in Macrophages and Splenocytes.” Biochimica et Biophysica Acta 1830 no. 4 (2013):2981–2988. Unfortunately, cyanobacteria can sometimes have a negative impact on human health. Genera such as Microcystis can form harmful cyanobacterial blooms , forming dense mats on bodies of water and producing large quantities of toxins that can harm wildlife and humans. These toxins have been implicated in tumors of the liver and diseases of the nervous system in animals and humans. 20 20 I. Stewart et al. Cyanobacterial Poisoning in Livestock, Wild Mammals and Birds – an Overview. Advances in Experimental Medicine and Biology 619 (2008):613–637. Table 4.8 summarizes the characteristics of important phototrophic bacteria. Phototrophic Bacteria Phylum Class Example Genus or Species Common Name Oxygenic or Anoxygenic Sulfur Deposition Cyanobacteria Cyanophyceae Microcystis aeruginosa Blue-green bacteria Oxygenic None Chlorobi Chlorobia Chlorobium Green sulfur bacteria Anoxygenic Outside the cell Chloroflexi (Division) Chloroflexi Chloroflexus Green nonsulfur bacteria Anoxygenic None Proteobacteria Alphaproteobacteria Rhodospirillum Purple nonsulfur bacteria Anoxygenic None Betaproteobacteria Rhodocyclus Purple nonsulfur bacteria Anoxygenic None Gammaproteobacteria Chromatium Purple sulfur bacteria Anoxygenic Inside the cell Table 4.8 Check Your Understanding What characteristic makes phototrophic bacteria different from other prokaryotes? 4.4 Gram-Positive Bacteria Learning Objectives Describe the unique features of each category of high G+C and low G+C gram-positive bacteria Identify similarities and differences between high G+C and low G+C bacterial groups Give an example of a bacterium of high G+C and low G+C group commonly associated with each category Prokaryotes are identified as gram-positive if they have a multiple layer matrix of peptidoglycan forming the cell wall. Crystal violet, the primary stain of the Gram stain procedure, is readily retained and stabilized within this matrix, causing gram-positive prokaryotes to appear purple under a brightfield microscope after Gram staining. For many years, the retention of Gram stain was one of the main criteria used to classify prokaryotes, even though some prokaryotes did not readily stain with either the primary or secondary stains used in the Gram stain procedure. Advances in nucleic acid biochemistry have revealed additional characteristics that can be used to classify gram-positive prokaryotes, namely the guanine to cytosine ratios (G+C) in DNA and the composition of 16S rRNA subunits. Microbiologists currently recognize two distinct groups of gram-positive, or weakly staining gram-positive, prokaryotes. The class Actinobacteria comprises the high G+C gram-positive bacteria , which have more than 50% guanine and cytosine nucleotides in their DNA. The class Bacilli comprises low G+C gram-positive bacteria , which have less than 50% of guanine and cytosine nucleotides in their DNA. Actinobacteria: High G+C Gram-Positive Bacteria The name Actinobacteria comes from the Greek words for rays and small rod , but Actinobacteria are very diverse. Their microscopic appearance can range from thin filamentous branching rods to coccobacilli. Some Actinobacteria are very large and complex, whereas others are among the smallest independently living organisms. Most Actinobacteria live in the soil, but some are aquatic. The vast majority are aerobic. One distinctive feature of this group is the presence of several different peptidoglycans in the cell wall. The genus Actinomyces is a much studied representative of Actinobacteria. Actinomyces spp. play an important role in soil ecology, and some species are human pathogens. A number of Actinomyces spp. inhabit the human mouth and are opportunistic pathogens, causing infectious diseases like periodontitis (inflammation of the gums) and oral abscesses. The species A. israelii is an anaerobe notorious for causing endocarditis (inflammation of the inner lining of the heart) ( Figure 4.18 ). The genus Mycobacterium is represented by bacilli covered with a mycolic acid coat. This waxy coat protects the bacteria from some antibiotics, prevents them from drying out, and blocks penetration by Gram stain reagents (see Staining Microscopic Specimens ). Because of this, a special acid-fast staining procedure is used to visualize these bacteria. The genus Mycobacterium is an important cause of a diverse group of infectious diseases. M. tuberculosis is the causative agent of tuberculosis , a disease that primarily impacts the lungs but can infect other parts of the body as well. It has been estimated that one-third of the world’s population has been infected with M. tuberculosis and millions of new infections occur each year. Treatment of M. tuberculosis is challenging and requires patients to take a combination of drugs for an extended time. Complicating treatment even further is the development and spread of multidrug-resistant strains of this pathogen. Another pathogenic species, M. leprae , is the cause of Hansen’s disease ( leprosy ), a chronic disease that impacts peripheral nerves and the integrity of the skin and mucosal surface of the respiratory tract. Loss of pain sensation and the presence of skin lesions increase susceptibility to secondary injuries and infections with other pathogens. Bacteria in the genus Corynebacterium contain diaminopimelic acid in their cell walls, and microscopically often form palisades , or pairs of rod-shaped cells resembling the letter V. Cells may contain metachromatic granules , intracellular storage of inorganic phosphates that are useful for identification of Corynebacterium . The vast majority of Corynebacterium spp. are nonpathogenic; however, C. diphtheria is the causative agent of diphtheria , a disease that can be fatal, especially in children ( Figure 4.18 ). C. diphtheria produces a toxin that forms a pseudomembrane in the patient’s throat, causing swelling, difficulty breathing, and other symptoms that can become serious if untreated. The genus Bifidobacterium consists of filamentous anaerobes, many of which are commonly found in the gastrointestinal tract, vagina, and mouth. In fact, Bifidobacterium spp. constitute a substantial part of the human gut microbiota and are frequently used as probiotics and in yogurt production. The genus Gardnerella , contains only one species, G. vaginalis . This species is defined as “gram-variable” because its small coccobacilli do not show consistent results when Gram stained ( Figure 4.18 ). Based on its genome, it is placed into the high G+C gram-positive group. G. vaginalis can cause bacterial vaginosis in women; symptoms are typically mild or even undetectable, but can lead to complications during pregnancy. Table 4.9 summarizes the characteristics of some important genera of Actinobacteria. Additional information on Actinobacteria appears in Appendix D . Actinobacteria: High G+C Gram-Positive Example Genus Microscopic Morphology Unique Characteristics Actinomyces Gram-positive bacillus; in colonies, shows fungus-like threads (hyphae) Facultative anaerobes; in soil, decompose organic matter; in the human mouth, may cause gum disease Arthrobacter Gram-positive bacillus (at the exponential stage of growth) or coccus (in stationary phase) Obligate aerobes; divide by “snapping,” forming V-like pairs of daughter cells; degrade phenol, can be used in bioremediation Bifidobacterium Gram-positive, filamentous actinobacterium Anaerobes commonly found in human gut microbiota Corynebacterium Gram-positive bacillus Aerobes or facultative anaerobes; form palisades; grow slowly; require enriched media in culture; C. diphtheriae causes diphtheria Frankia Gram-positive, fungus-like (filamentous) bacillus Nitrogen-fixing bacteria; live in symbiosis with legumes Gardnerella Gram-variable coccobacillus Colonize the human vagina, may alter the microbial ecology, thus leading to vaginosis Micrococcus Gram-positive coccus, form microscopic clusters Ubiquitous in the environment and on the human skin; oxidase-positive (as opposed to morphologically similar S. aureus ); some are opportunistic pathogens Mycobacterium Gram-positive, acid-fast bacillus Slow growing, aerobic, resistant to drying and phagocytosis; covered with a waxy coat made of mycolic acid; M. tuberculosis causes tuberculosis; M. leprae causes leprosy Nocardia Weakly gram-positive bacillus; forms acid-fast branches May colonize the human gingiva; may cause severe pneumonia and inflammation of the skin Propionibacterium Gram-positive bacillus Aerotolerant anaerobe; slow-growing; P. acnes reproduces in the human sebaceous glands and may cause or contribute to acne Rhodococcus Gram-positive bacillus Strict aerobe; used in industry for biodegradation of pollutants; R. fascians is a plant pathogen, and R. equi causes pneumonia in foals Streptomyces Gram-positive, fungus-like (filamentous) bacillus Very diverse genus (>500 species); aerobic, spore-forming bacteria; scavengers, decomposers found in soil (give the soil its “earthy” odor); used in pharmaceutical industry as antibiotic producers (more than two-thirds of clinically useful antibiotics) Table 4.9 Check Your Understanding What is one distinctive feature of Actinobacteria? Low G+C Gram-positive Bacteria The low G+C gram-positive bacteria have less than 50% guanine and cytosine in their DNA, and this group of bacteria includes a number of genera of bacteria that are pathogenic. Clinical Focus Part 3 Based on her symptoms, Marsha’s doctor suspected that she had a case of tuberculosis. Although less common in the United States, tuberculosis is still extremely common in many parts of the world, including Nigeria. Marsha’s work there in a medical lab likely exposed her to Mycobacterium tuberculosis , the bacterium that causes tuberculosis. Marsha’s doctor ordered her to stay at home, wear a respiratory mask, and confine herself to one room as much as possible. He also said that Marsha had to take one semester off school. He prescribed isoniazid and rifampin, antibiotics used in a drug cocktail to treat tuberculosis, which Marsha was to take three times a day for at least three months. Why did the doctor order Marsha to stay home for three months? Jump to the next Clinical Focus box. Go back to the previous Clinical Focus box. Clostridia One large and diverse class of low G+C gram-positive bacteria is Clostridia. The best studied genus of this class is Clostridium . These rod-shaped bacteria are generally obligate anaerobes that produce endospores and can be found in anaerobic habitats like soil and aquatic sediments rich in organic nutrients. The endospores may survive for many years. Clostridium spp. produce more kinds of protein toxins than any other bacterial genus, and several species are human pathogens. C. perfringens is the third most common cause of food poisoning in the United States and is the causative agent of an even more serious disease called gas gangrene . Gas gangrene occurs when C. perfringens endospores enter a wound and germinate, becoming viable bacterial cells and producing a toxin that can cause the necrosis (death) of tissue. C. tetani , which causes tetanus , produces a neurotoxin that is able to enter neurons, travel to regions of the central nervous system where it blocks the inhibition of nerve impulses involved in muscle contractions, and cause a life-threatening spastic paralysis. C. botulinum produces botulinum neurotoxin , the most lethal biological toxin known. Botulinum toxin is responsible for rare but frequently fatal cases of botulism . The toxin blocks the release of acetylcholine in neuromuscular junctions, causing flaccid paralysis. In very small concentrations, botulinum toxin has been used to treat muscle pathologies in humans and in a cosmetic procedure to eliminate wrinkles. C. difficile is a common source of hospital-acquired infections ( Figure 4.19 ) that can result in serious and even fatal cases of colitis (inflammation of the large intestine). Infections often occur in patients who are immunosuppressed or undergoing antibiotic therapy that alters the normal microbiota of the gastrointestinal tract. Appendix D lists the genera, species, and related diseases for Clostridia. Lactobacillales The order Lactobacillales comprises low G+C gram-positive bacteria that include both bacilli and cocci in the genera Lactobacillus , Leuconostoc , Enterococcus , and Streptococcus . Bacteria of the latter three genera typically are spherical or ovoid and often form chains. Streptococcus , the name of which comes from the Greek word for twisted chain , is responsible for many types of infectious diseases in humans. Species from this genus, often referred to as streptococci , are usually classified by serotypes called Lancefield groups, and by their ability to lyse red blood cells when grown on blood agar. S. pyogenes belongs to the Lancefield group A, β-hemolytic Streptococcus . This species is considered a pyogenic pathogen because of the associated pus production observed with infections it causes ( Figure 4.20 ). S. pyogenes is the most common cause of bacterial pharyngitis ( strep throat ); it is also an important cause of various skin infections that can be relatively mild (e.g., impetigo ) or life threatening (e.g., necrotizing fasciitis , also known as flesh eating disease), life threatening. The nonpyogenic (i.e., not associated with pus production) streptococci are a group of streptococcal species that are not a taxon but are grouped together because they inhabit the human mouth. The nonpyogenic streptococci do not belong to any of the Lancefield groups. Most are commensals, but a few, such as S. mutans , are implicated in the development of dental caries. S. pneumoniae (commonly referred to as pneumococcus), is a Streptococcus species that also does not belong to any Lancefield group . S. pneumoniae cells appear microscopically as diplococci, pairs of cells, rather than the long chains typical of most streptococci. Scientists have known since the 19th century that S. pneumoniae causes pneumonia and other respiratory infections. However, this bacterium can also cause a wide range of other diseases, including meningitis, septicemia, osteomyelitis, and endocarditis, especially in newborns, the elderly, and patients with immunodeficiency. Bacilli The name of the class Bacilli suggests that it is made up of bacteria that are bacillus in shape, but it is a morphologically diverse class that includes bacillus-shaped and cocccus-shaped genera. Among the many genera in this class are two that are very important clinically: Bacillus and Staphylococcus . Bacteria in the genus Bacillus are bacillus in shape and can produce endospores . They include aerobes or facultative anaerobes. A number of Bacillus spp. are used in various industries, including the production of antibiotics (e.g., barnase), enzymes (e.g., alpha-amylase, BamH1 restriction endonuclease), and detergents (e.g., subtilisin). Two notable pathogens belong to the genus Bacillus. B. anthracis is the pathogen that causes anthrax , a severe disease that affects wild and domesticated animals and can spread from infected animals to humans. Anthrax manifests in humans as charcoal-black ulcers on the skin, severe enterocolitis, pneumonia, and brain damage due to swelling. If untreated, anthrax is lethal. B. cereus , a closely related species, is a pathogen that may cause food poisoning. It is a rod-shaped species that forms chains. Colonies appear milky white with irregular shapes when cultured on blood agar ( Figure 4.21 ). One other important species is B. thuringiensis . This bacterium produces a number of substances used as insecticides because they are toxic for insects. The genus Staphylococcus also belongs to the class Bacilli, even though its shape is coccus rather than a bacillus. The name Staphylococcus comes from a Greek word for bunches of grapes , which describes their microscopic appearance in culture ( Figure 4.22 ). Staphylococcus spp. are facultative anaerobic, halophilic, and nonmotile. The two best-studied species of this genus are S. epidermidis and S. aureus . S. epidermidis , whose main habitat is the human skin, is thought to be nonpathogenic for humans with healthy immune systems, but in patients with immunodeficiency, it may cause infections in skin wounds and prostheses (e.g., artificial joints, heart valves) . S. epidermidis is also an important cause of infections associated with intravenous catheters. This makes it a dangerous pathogen in hospital settings, where many patients may be immunocompromised. Strains of S. aureus cause a wide variety of infections in humans, including skin infections that produce boils, carbuncles, cellulitis, or impetigo. Certain strains of S. aureus produce a substance called enterotoxin , which can cause severe enteritis, often called staph food poisoning. Some strains of S. aureus produce the toxin responsible for toxic shock syndrome , which can result in cardiovascular collapse and death. Many strains of S. aureus have developed resistance to antibiotics. Some antibiotic-resistant strains are designated as methicillin-resistant S. aureus ( MRSA ) and vancomycin-resistant S. aureus (VRSA) . These strains are some of the most difficult to treat because they exhibit resistance to nearly all available antibiotics, not just methicillin and vancomycin. Because they are difficult to treat with antibiotics, infections can be lethal. MRSA and VRSA are also contagious, posing a serious threat in hospitals, nursing homes, dialysis facilities, and other places where there are large populations of elderly, bedridden, and/or immunocompromised patients. Appendix D lists the genera, species, and related diseases for bacilli. Mycoplasmas Although Mycoplasma spp. do not possess a cell wall and, therefore, are not stained by Gram-stain reagents, this genus is still included with the low G+C gram-positive bacteria. The genus Mycoplasma includes more than 100 species, which share several unique characteristics. They are very small cells, some with a diameter of about 0.2 μm, which is smaller than some large viruses. They have no cell walls and, therefore, are pleomorphic , meaning that they may take on a variety of shapes and can even resemble very small animal cells. Because they lack a characteristic shape, they can be difficult to identify. One species, M. pneumoniae , causes the mild form of pneumonia known as “ walking pneumonia ” or “ atypical pneumonia .” This form of pneumonia is typically less severe than forms caused by other bacteria or viruses. Table 4.10 summarizes the characteristics of notable genera low G+C Gram-positive bacteria. Bacilli: Low G+C Gram-Positive Bacteria Example Genus Microscopic Morphology Unique Characteristics Bacillus Large, gram-positive bacillus Aerobes or facultative anaerobes; form endospores; B. anthracis causes anthrax in cattle and humans, B. cereus may cause food poisoning Clostridium Gram-positive bacillus Strict anaerobes; form endospores; all known species are pathogenic, causing tetanus, gas gangrene, botulism, and colitis Enterococcus Gram-positive coccus; forms microscopic pairs in culture (resembling Streptococcus pneumoniae ) Anaerobic aerotolerant bacteria, abundant in the human gut, may cause urinary tract and other infections in the nosocomial environment Lactobacillus Gram-positive bacillus Facultative anaerobes; ferment sugars into lactic acid; part of the vaginal microbiota; used as probiotics Leuconostoc Gram-positive coccus; may form microscopic chains in culture Fermenter, used in food industry to produce sauerkraut and kefir Mycoplasma The smallest bacteria; appear pleomorphic under electron microscope Have no cell wall; classified as low G+C Gram-positive bacteria because of their genome; M. pneumoniae causes “walking” pneumonia Staphylococcus Gram-positive coccus; forms microscopic clusters in culture that resemble bunches of grapes Tolerate high salt concentration; facultative anaerobes; produce catalase; S. aureus can also produce coagulase and toxins responsible for local (skin) and generalized infections Streptococcus Gram-positive coccus; forms chains or pairs in culture Diverse genus; classified into groups based on sharing certain antigens; some species cause hemolysis and may produce toxins responsible for human local (throat) and generalized disease Ureaplasma Similar to Mycoplasma Part of the human vaginal and lower urinary tract microbiota; may cause inflammation, sometimes leading to internal scarring and infertility Table 4.10 Check Your Understanding Name some ways in which streptococci are classified. Name one pathogenic low G+C gram-positive bacterium and a disease it causes. Clinical Focus Resolution Marsha’s sputum sample was sent to the microbiology lab to confirm the identity of the microorganism causing her infection. The lab also performed antimicrobial susceptibility testing (AST) on the sample to confirm that the physician has prescribed the correct antimicrobial drugs. Direct microscopic examination of the sputum revealed acid-fast bacteria (AFB) present in Marsha’s sputum. When placed in culture, there were no signs of growth for the first 8 days, suggesting that microorganism was either dead or growing very slowly. Slow growth is a distinctive characteristic of M. tuberculosis . After four weeks, the lab microbiologist observed distinctive colorless granulated colonies ( Figure 4.23 ). The colonies contained AFB showing the same microscopic characteristics as those revealed during the direct microscopic examination of Marsha’s sputum. To confirm the identification of the AFB, samples of the colonies were analyzed using nucleic acid hybridization, or direct nucleic acid amplification (NAA) testing. When a bacterium is acid-fast, it is classified in the family Mycobacteriaceae . DNA sequencing of variable genomic regions of the DNA extracted from these bacteria revealed that it was high G+C. This fact served to finalize Marsha’s diagnosis as infection with M. tuberculosis . After nine months of treatment with the drugs prescribed by her doctor, Marsha made a full recovery. Go back to the previous Clinical Focus box. Eye on Ethics Biopiracy and Bioprospecting In 1969, an employee of a Swiss pharmaceutical company was vacationing in Norway and decided to collect some soil samples. He took them back to his lab, and the Swiss company subsequently used the fungus Tolypocladium inflatum in those samples to develop cyclosporine A, a drug widely used in patients who undergo tissue or organ transplantation. The Swiss company earns more than $1 billion a year for production of cyclosporine A, yet Norway receives nothing in return—no payment to the government or benefit for the Norwegian people. Despite the fact the cyclosporine A saves numerous lives, many consider the means by which the soil samples were obtained to be an act of “biopiracy,” essentially a form of theft. Do the ends justify the means in a case like this? Nature is full of as-yet-undiscovered bacteria and other microorganisms that could one day be used to develop new life-saving drugs or treatments. 21 Pharmaceutical and biotechnology companies stand to reap huge profits from such discoveries, but ethical questions remain. To whom do biological resources belong? Should companies who invest (and risk) millions of dollars in research and development be required to share revenue or royalties for the right to access biological resources? 21 J. Andre. Bioethics as Practice . Chapel Hill, NC: University of North Carolina Press, 2002. Compensation is not the only issue when it comes to bioprospecting. Some communities and cultures are philosophically opposed to bioprospecting, fearing unforeseen consequences of collecting genetic or biological material. Native Hawaiians, for example, are very protective of their unique biological resources. For many years, it was unclear what rights government agencies, private corporations, and citizens had when it came to collecting samples of microorganisms from public land. Then, in 1993, the Convention on Biological Diversity granted each nation the rights to any genetic and biological material found on their own land. Scientists can no longer collect samples without a prior arrangement with the land owner for compensation. This convention now ensures that companies act ethically in obtaining the samples they use to create their products. 4.5 Deeply Branching Bacteria Learning Objectives Describe the unique features of deeply branching bacteria Give examples of significant deeply branching bacteria On a phylogenetic tree (see A Systematic Approach ), the trunk or root of the tree represents a common ancient evolutionary ancestor, often called the last universal common ancestor (LUCA) , and the branches are its evolutionary descendants. Scientists consider the deeply branching bacteria , such as the genus Acetothermus , to be the first of these non-LUCA forms of life produced by evolution some 3.5 billion years ago. When placed on the phylogenetic tree, they stem from the common root of life, deep and close to the LUCA root—hence the name “deeply branching” ( Figure 4.24 ). The deeply branching bacteria may provide clues regarding the structure and function of ancient and now extinct forms of life. We can hypothesize that ancient bacteria, like the deeply branching bacteria that still exist, were thermophiles or hyperthermophiles , meaning that they thrived at very high temperatures. Acetothermus paucivorans , a gram-negative anaerobic bacterium discovered in 1988 in sewage sludge, is a thermophile growing at an optimal temperature of 58 °C. 22 Scientists have determined it to be the deepest branching bacterium, or the closest evolutionary relative of the LUCA ( Figure 4.24 ). 22 G. Dietrich et al. “ Acetothermus paucivorans , gen. nov., sp. Nov., a Strictly Anaerobic, Thermophilic Bacterium From Sewage Sludge, Fermenting Hexoses to Acetate, CO 2 , and H 2 .” Systematic and Applied Microbiology 10 no. 2 (1988):174–179. The class Aquificae includes deeply branching bacteria that are adapted to the harshest conditions on our planet, resembling the conditions thought to dominate the earth when life first appeared. Bacteria from the genus Aquifex are hyperthermophiles, living in hot springs at a temperature higher than 90 °C. The species A. pyrophilus thrives near underwater volcanoes and thermal ocean vents, where the temperature of water (under high pressure) can reach 138 °C. Aquifex bacteria use inorganic substances as nutrients. For example, A. pyrophilus can reduce oxygen, and it is able to reduce nitrogen in anaerobic conditions. They also show a remarkable resistance to ultraviolet light and ionizing radiation. Taken together, these observations support the hypothesis that the ancient ancestors of deeply branching bacteria began evolving more than 3 billion years ago, when the earth was hot and lacked an atmosphere, exposing the bacteria to nonionizing and ionizing radiation. The class Thermotogae is represented mostly by hyperthermophilic, as well as some mesophilic (preferring moderate temperatures), anaerobic gram-negative bacteria whose cells are wrapped in a peculiar sheath-like outer membrane called a toga . The thin layer of peptidoglycan in their cell wall has an unusual structure; it contains diaminopimelic acid and D-lysine. These bacteria are able to use a variety of organic substrates and produce molecular hydrogen, which can be used in industry. The class contains several genera, of which the best known is the genus Thermotoga . One species of this genus, T. maritima , lives near the thermal ocean vents and thrives in temperatures of 90 °C; another species, T. subterranea , lives in underground oil reservoirs. Finally, the deeply branching bacterium Deinococcus radiodurans belongs to a genus whose name is derived from a Greek word meaning terrible berry . Nicknamed “ Conan the Bacterium ,” D. radiodurans is considered a polyextremophile because of its ability to survive under the many different kinds of extreme conditions—extreme heat, drought, vacuum, acidity, and radiation. It owes its name to its ability to withstand doses of ionizing radiation that kill all other known bacteria; this special ability is attributed to some unique mechanisms of DNA repair. 4.6 Archaea Learning Objectives Describe the unique features of each category of Archaea Explain why archaea might not be associated with human microbiomes or pathology Give common examples of archaea commonly associated with unique environmental habitats Like organisms in the domain Bacteria, organisms of the domain Archaea are all unicellular organisms. However, archaea differ structurally from bacteria in several significant ways, as discussed in Unique Characteristics of Prokaryotic Cells . To summarize: The archaeal cell membrane is composed of ether linkages with branched isoprene chains (as opposed to the bacterial cell membrane, which has ester linkages with unbranched fatty acids). Archaeal cell walls lack peptidoglycan, but some contain a structurally similar substance called pseudopeptidoglycan or pseudomurein . The genomes of Archaea are larger and more complex than those of bacteria. Domain Archaea is as diverse as domain Bacteria, and its representatives can be found in any habitat. Some archaea are mesophiles , and many are extremophiles , preferring extreme hot or cold, extreme salinity, or other conditions that are hostile to most other forms of life on earth. Their metabolism is adapted to the harsh environments, and they can perform methanogenesis , for example, which bacteria and eukaryotes cannot. The size and complexity of the archaeal genome makes it difficult to classify. Most taxonomists agree that within the Archaea, there are currently five major phyla: Crenarchaeota , Euryarchaeota , Korarchaeota , Nanoarchaeota , and Thaumarchaeota . There are likely many other archaeal groups that have not yet been systematically studied and classified. With few exceptions, archaea are not present in the human microbiota, and none are currently known to be associated with infectious diseases in humans, animals, plants, or microorganisms. However, many play important roles in the environment and may thus have an indirect impact on human health. Crenarchaeota Crenarchaeota is a class of Archaea that is extremely diverse, containing genera and species that differ vastly in their morphology and requirements for growth. All Crenarchaeota are aquatic organisms, and they are thought to be the most abundant microorganisms in the oceans. Most, but not all, Crenarchaeota are hyperthermophiles; some of them (notably, the genus Pyrolobus ) are able to grow at temperatures up to 113 °C. 23 23 E. Blochl et al.“ Pyrolobus fumani , gen. and sp. nov., represents a novel group of Archaea, extending the upper temperature limit for life to 113 ° C.” Extremophiles 1 (1997):14–21. Archaea of the genus Sulfolobus ( Figure 4.26 ) are thermophiles that prefer temperatures around 70–80°C and acidophiles that prefer a pH of 2–3. 24 Sulfolobus can live in aerobic or anaerobic environments. In the presence of oxygen, Sulfolobus spp. use metabolic processes similar to those of heterotrophs. In anaerobic environments, they oxidize sulfur to produce sulfuric acid, which is stored in granules. Sulfolobus spp. are used in biotechnology for the production of thermostable and acid-resistant proteins called affitins . 25 Affitins can bind and neutralize various antigens (molecules found in toxins or infectious agents that provoke an immune response from the body). 24 T.D. Brock et al. “ Sulfolobus : A New Genus of Sulfur-Oxidizing Bacteria Living at Low pH and High Temperature.” Archiv für Mikrobiologie 84 no. 1 (1972):54–68. 25 S. Pacheco et al. “Affinity Transfer to the Archaeal Extremophilic Sac7d Protein by Insertion of a CDR.” Protein Engineering Design and Selection 27 no. 10 (2014):431-438. Another genus, Thermoproteus , is represented by strictly anaerobic organisms with an optimal growth temperature of 85 °C. They have flagella and, therefore, are motile. Thermoproteus has a cellular membrane in which lipids form a monolayer rather than a bilayer, which is typical for archaea. Its metabolism is autotrophic. To synthesize ATP, Thermoproteus spp. reduce sulfur or molecular hydrogen and use carbon dioxide or carbon monoxide as a source of carbon. Thermoproteus is thought to be the deepest-branching genus of Archaea, and thus is a living example of some of our planet’s earliest forms of life. Check Your Understanding What types of environments do Crenarchaeota prefer? Euryarchaeota The phylum Euryarchaeota includes several distinct classes. Species in the classes Methanobacteria, Methanococci, and Methanomicrobia represent Archaea that can be generally described as methanogens. Methanogens are unique in that they can reduce carbon dioxide in the presence of hydrogen, producing methane. They can live in the most extreme environments and can reproduce at temperatures varying from below freezing to boiling. Methanogens have been found in hot springs as well as deep under ice in Greenland. Methanogens also produce gases in ruminants and humans. Some scientists have even hypothesized that methanogen s may inhabit the planet Mars because the mixture of gases produced by methanogens resembles the makeup of the Martian atmosphere. 26 26 R.R. Britt “Crater Critters: Where Mars Microbes Might Lurk.” http://www.space.com/1880-crater-critters-mars-microbes-lurk.html. Accessed April 7, 2015. The class Halobacteria (which was named before scientists recognized the distinction between Archaea and Bacteria) includes halophilic (“salt-loving”) archaea. Halobacteria require a very high concentrations of sodium chloride in their aquatic environment. The required concentration is close to saturation, at 36%; such environments include the Dead Sea as well as some salty lakes in Antarctica and south-central Asia. One remarkable feature of these organisms is that they perform photosynthesis using the protein bacteriorhodopsin , which gives them, and the bodies of water they inhabit, a beautiful purple color ( Figure 4.27 ). Notable species of Halobacteria include Halobacterium salinarum , which may be the oldest living organism on earth; scientists have isolated its DNA from fossils that are 250 million years old. 27 Another species, Haloferax volcanii , shows a very sophisticated system of ion exchange, which enables it to balance the concentration of salts at high temperatures. 27 H. Vreeland et al. “Fatty acid and DA Analyses of Permian Bacterium Isolated From Ancient Salt Crystals Reveal Differences With Their Modern Relatives.” Extremophiles 10 (2006):71–78. Check Your Understanding Where do Halobacteria live? Micro Connections Finding a Link Between Archaea and Disease Archaea are not known to cause any disease in humans, animals, plants, bacteria, or in other archaea. Although this makes sense for the extremophiles, not all archaea live in extreme environments. Many genera and species of Archaea are mesophiles, so they can live in human and animal microbiomes, although they rarely do. As we have learned, some methanogens exist in the human gastrointestinal tract. Yet we have no reliable evidence pointing to any archaean as the causative agent of any human disease. Still, scientists have attempted to find links between human disease and archaea. For example, in 2004, Lepp et al. presented evidence that an archaean called Methanobrevibacter oralis inhabits the gums of patients with periodontal disease. The authors suggested that the activity of these methanogens causes the disease. 28 However, it was subsequently shown that there was no causal relationship between M. oralis and periodontitis. It seems more likely that periodontal disease causes an enlargement of anaerobic regions in the mouth that are subsequently populated by M. oralis . 29 28 P.W. Lepp et al. “Methanogenic Archaea and Human Gum Disease.” Proceedings of the National Academies of Science of the United States of America 101 no. 16 (2004):6176–6181. 29 R.I. Aminov. “Role of Archaea in Human Disease.” Frontiers in Cellular and Infection Microbiology 3 (2013):42. There remains no good answer as to why archaea do not seem to be pathogenic, but scientists continue to speculate and hope to find the answer.
anatomy_and_physiology
Chapter Objectives After studying this chapter, you will be able to: Identify and describe the interior and exterior parts of the human heart Describe the path of blood through the cardiac circuits Describe the size, shape, and location of the heart Compare cardiac muscle to skeletal and smooth muscle Explain the cardiac conduction system Describe the process and purpose of an electrocardiogram Explain the cardiac cycle Calculate cardiac output Describe the effects of exercise on cardiac output and heart rate Name the centers of the brain that control heart rate and describe their function Identify other factors affecting heart rate Describe fetal heart development Introduction In this chapter, you will explore the remarkable pump that propels the blood into the vessels. There is no single better word to describe the function of the heart other than “pump,” since its contraction develops the pressure that ejects blood into the major vessels: the aorta and pulmonary trunk. From these vessels, the blood is distributed to the remainder of the body. Although the connotation of the term “pump” suggests a mechanical device made of steel and plastic, the anatomical structure is a living, sophisticated muscle. As you read this chapter, try to keep these twin concepts in mind: pump and muscle. Although the term “heart” is an English word, cardiac (heart-related) terminology can be traced back to the Latin term, “kardia.” Cardiology is the study of the heart, and cardiologists are the physicians who deal primarily with the heart.
[ { "answer": { "ans_choice": 3, "ans_text": "endocardium" }, "bloom": "1", "hl_context": "When the myocardium of the ventricle contracts , pressure within the ventricular chamber rises . Blood , like any fluid , flows from higher pressure to lower pressure areas , in this case , toward the pulmonary trunk and the atrium . <hl> To prevent any potential backflow , the papillary muscles also contract , generating tension on the chordae tendineae . <hl> <hl> This prevents the flaps of the valves from being forced into the atria and regurgitation of the blood back into the atria during ventricular contraction . <hl> Figure 19.11 shows papillary muscles and chordae tendineae attached to the tricuspid valve .", "hl_sentences": "To prevent any potential backflow , the papillary muscles also contract , generating tension on the chordae tendineae . This prevents the flaps of the valves from being forced into the atria and regurgitation of the blood back into the atria during ventricular contraction .", "question": { "cloze_format": "___ is/are not important in preventing backflow of blood.", "normal_format": "Which of the following is not important in preventing backflow of blood?", "question_choices": [ "chordae tendineae", "papillary muscles", "AV valves", "endocardium" ], "question_id": "fs-id2627639", "question_text": "Which of the following is not important in preventing backflow of blood?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 0, "ans_text": "mitral" }, "bloom": "1", "hl_context": "<hl> Located at the opening between the left atrium and left ventricle is the mitral valve , also called the bicuspid valve or the left atrioventricular valve . <hl> Structurally , this valve consists of two cusps , compared to the three cusps of the tricuspid valve . In a clinical setting , the valve is referred to as the mitral valve , rather than the bicuspid valve . The two cusps of the mitral valve are attached by chordae tendineae to two papillary muscles that project from the wall of the ventricle . After exchange of gases in the pulmonary capillaries , blood returns to the left atrium high in oxygen via one of the four pulmonary veins . While the left atrium does not contain pectinate muscles , it does have an auricle that includes these pectinate ridges . Blood flows nearly continuously from the pulmonary veins back into the atrium , which acts as the receiving chamber , and from here through an opening into the left ventricle . Most blood flows passively into the heart while both the atria and ventricles are relaxed , but toward the end of the ventricular relaxation period , the left atrium will contract , pumping blood into the ventricle . This atrial contraction accounts for approximately 20 percent of ventricular filling . <hl> The opening between the left atrium and ventricle is guarded by the mitral valve . <hl>", "hl_sentences": "Located at the opening between the left atrium and left ventricle is the mitral valve , also called the bicuspid valve or the left atrioventricular valve . The opening between the left atrium and ventricle is guarded by the mitral valve .", "question": { "cloze_format": "The valve that separates the left atrium from the left ventricle is the ___.", "normal_format": "Which valve separates the left atrium from the left ventricle?", "question_choices": [ "mitral", "tricuspid", "pulmonary", "aortic" ], "question_id": "fs-id2367256", "question_text": "Which valve separates the left atrium from the left ventricle?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 0, "ans_text": "tricuspid, pulmonary semilunar, bicuspid, aortic semilunar" }, "bloom": "1", "hl_context": "<hl> At the base of the aorta is the aortic semilunar valve , or the aortic valve , which prevents backflow from the aorta . <hl> It normally is composed of three flaps . When the ventricle relaxes and blood attempts to flow back into the ventricle from the aorta , blood will fill the cusps of the valve , causing it to close and producing an audible sound . <hl> Located at the opening between the left atrium and left ventricle is the mitral valve , also called the bicuspid valve or the left atrioventricular valve . <hl> Structurally , this valve consists of two cusps , compared to the three cusps of the tricuspid valve . In a clinical setting , the valve is referred to as the mitral valve , rather than the bicuspid valve . The two cusps of the mitral valve are attached by chordae tendineae to two papillary muscles that project from the wall of the ventricle . <hl> A transverse section through the heart slightly above the level of the atrioventricular septum reveals all four heart valves along the same plane ( Figure 19.12 ) . <hl> <hl> The valves ensure unidirectional blood flow through the heart . <hl> <hl> Between the right atrium and the right ventricle is the right atrioventricular valve , or tricuspid valve . <hl> It typically consists of three flaps , or leaflets , made of endocardium reinforced with additional connective tissue . The flaps are connected by chordae tendineae to the papillary muscles , which control the opening and closing of the valves . <hl> Emerging from the right ventricle at the base of the pulmonary trunk is the pulmonary semilunar valve , or the pulmonary valve ; it is also known as the pulmonic valve or the right semilunar valve . <hl> The pulmonary valve is comprised of three small flaps of endothelium reinforced with connective tissue . When the ventricle relaxes , the pressure differential causes blood to flow back into the ventricle from the pulmonary trunk . This flow of blood fills the pocket-like flaps of the pulmonary valve , causing the valve to close and producing an audible sound . Unlike the atrioventricular valves , there are no papillary muscles or chordae tendineae associated with the pulmonary valve .", "hl_sentences": "At the base of the aorta is the aortic semilunar valve , or the aortic valve , which prevents backflow from the aorta . Located at the opening between the left atrium and left ventricle is the mitral valve , also called the bicuspid valve or the left atrioventricular valve . A transverse section through the heart slightly above the level of the atrioventricular septum reveals all four heart valves along the same plane ( Figure 19.12 ) . The valves ensure unidirectional blood flow through the heart . Between the right atrium and the right ventricle is the right atrioventricular valve , or tricuspid valve . Emerging from the right ventricle at the base of the pulmonary trunk is the pulmonary semilunar valve , or the pulmonary valve ; it is also known as the pulmonic valve or the right semilunar valve .", "question": { "cloze_format": "____ lists the valves in the order through which the blood flows from the vena cava through the heart.", "normal_format": "Which of the following lists the valves in the order through which the blood flows from the vena cava through the heart?", "question_choices": [ "tricuspid, pulmonary semilunar, bicuspid, aortic semilunar", "mitral, pulmonary semilunar, bicuspid, aortic semilunar", "aortic semilunar, pulmonary semilunar, tricuspid, bicuspid", "bicuspid, aortic semilunar, tricuspid, pulmonary semilunar" ], "question_id": "fs-id1228297", "question_text": "Which of the following lists the valves in the order through which the blood flows from the vena cava through the heart?" }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 2, "ans_text": "right atrium" }, "bloom": "1", "hl_context": "<hl> The right atrium serves as the receiving chamber for blood returning to the heart from the systemic circulation . <hl> The two major systemic veins , the superior and inferior venae cavae , and the large coronary vein called the coronary sinus that drains the heart myocardium empty into the right atrium . The superior vena cava drains blood from regions superior to the diaphragm : the head , neck , upper limbs , and the thoracic region . It empties into the superior and posterior portions of the right atrium . The inferior vena cava drains blood from areas inferior to the diaphragm : the lower limbs and abdominopelvic region of the body . It , too , empties into the posterior portion of the atria , but inferior to the opening of the superior vena cava . Immediately superior and slightly medial to the opening of the inferior vena cava on the posterior surface of the atrium is the opening of the coronary sinus . This thin-walled vessel drains most of the coronary veins that return systemic blood from the heart . The majority of the internal heart structures discussed in this and subsequent sections are illustrated in Figure 19.9 . The human heart consists of four chambers : The left side and the right side each have one atrium and one ventricle . <hl> Each of the upper chambers , the right atrium ( plural = atria ) and the left atrium , acts as a receiving chamber and contracts to push blood into the lower chambers , the right ventricle and the left ventricle . <hl> The ventricles serve as the primary pumping chambers of the heart , propelling blood to the lungs or to the rest of the body .", "hl_sentences": "The right atrium serves as the receiving chamber for blood returning to the heart from the systemic circulation . Each of the upper chambers , the right atrium ( plural = atria ) and the left atrium , acts as a receiving chamber and contracts to push blood into the lower chambers , the right ventricle and the left ventricle .", "question": { "cloze_format": "The chamber that initially receives blood from the systemic circuit is the ___ .", "normal_format": "Which chamber initially receives blood from the systemic circuit?", "question_choices": [ "left atrium", "left ventricle", "right atrium", "right ventricle" ], "question_id": "fs-id2002743", "question_text": "Which chamber initially receives blood from the systemic circuit?" }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 1, "ans_text": "endocardium" }, "bloom": "1", "hl_context": "<hl> Once regarded as a simple lining layer , recent evidence indicates that the endothelium of the endocardium and the coronary capillaries may play active roles in regulating the contraction of the muscle within the myocardium . <hl> <hl> The endothelium may also regulate the growth patterns of the cardiac muscle cells throughout life , and the endothelins it secretes create an environment in the surrounding tissue fluids that regulates ionic concentrations and states of contractility . <hl> <hl> Endothelins are potent vasoconstrictors and , in a normal individual , establish a homeostatic balance with other vasoconstrictors and vasodilators . <hl> <hl> The innermost layer of the heart wall , the endocardium , is joined to the myocardium with a thin layer of connective tissue . <hl> The endocardium lines the chambers where the blood circulates and covers the heart valves . It is made of simple squamous epithelium called endothelium , which is continuous with the endothelial lining of the blood vessels ( see Figure 19.5 ) .", "hl_sentences": "Once regarded as a simple lining layer , recent evidence indicates that the endothelium of the endocardium and the coronary capillaries may play active roles in regulating the contraction of the muscle within the myocardium . The endothelium may also regulate the growth patterns of the cardiac muscle cells throughout life , and the endothelins it secretes create an environment in the surrounding tissue fluids that regulates ionic concentrations and states of contractility . Endothelins are potent vasoconstrictors and , in a normal individual , establish a homeostatic balance with other vasoconstrictors and vasodilators . The innermost layer of the heart wall , the endocardium , is joined to the myocardium with a thin layer of connective tissue .", "question": { "cloze_format": "The ________ layer secretes chemicals that help to regulate ionic environments and strength of contraction and serve as powerful vasoconstrictors.", "normal_format": "Which layer secretes chemicals that help to regulate ionic environments and strength of contraction and serve as powerful vasoconstrictors?", "question_choices": [ "pericardial sac", "endocardium", "myocardium", "epicardium" ], "question_id": "fs-id2515169", "question_text": "The ________ layer secretes chemicals that help to regulate ionic environments and strength of contraction and serve as powerful vasoconstrictors." }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 1, "ans_text": "left ventricle" }, "bloom": "1", "hl_context": "<hl> Recall that , although both sides of the heart will pump the same amount of blood , the muscular layer is much thicker in the left ventricle compared to the right ( see Figure 19.8 ) . <hl> Like the right ventricle , the left also has trabeculae carneae , but there is no moderator band . The mitral valve is connected to papillary muscles via chordae tendineae . There are two papillary muscles on the left — the anterior and posterior — as opposed to three on the right . <hl> Although the ventricles on the right and left sides pump the same amount of blood per contraction , the muscle of the left ventricle is much thicker and better developed than that of the right ventricle . <hl> In order to overcome the high resistance required to pump blood into the long systemic circuit , the left ventricle must generate a great amount of pressure . The right ventricle does not need to generate as much pressure , since the pulmonary circuit is shorter and provides less resistance . Figure 19.8 illustrates the differences in muscular thickness needed for each of the ventricles . <hl> The middle and thickest layer is the myocardium , made largely of cardiac muscle cells . <hl> It is built upon a framework of collagenous fibers , plus the blood vessels that supply the myocardium and the nerve fibers that help regulate the heart . It is the contraction of the myocardium that pumps blood through the heart and into the major arteries . The muscle pattern is elegant and complex , as the muscle cells swirl and spiral around the chambers of the heart . They form a figure 8 pattern around the atria and around the bases of the great vessels . Deeper ventricular muscles also form a figure 8 around the two ventricles and proceed toward the apex . More superficial layers of ventricular muscle wrap around both ventricles . This complex swirling pattern allows the heart to pump blood more effectively than a simple linear pattern would . Figure 19.7 illustrates the arrangement of muscle cells . <hl> The wall of the heart is composed of three layers of unequal thickness . <hl> <hl> From superficial to deep , these are the epicardium , the myocardium , and the endocardium ( see Figure 19.5 ) . <hl> The outermost layer of the wall of the heart is also the innermost layer of the pericardium , the epicardium , or the visceral pericardium discussed earlier .", "hl_sentences": "Recall that , although both sides of the heart will pump the same amount of blood , the muscular layer is much thicker in the left ventricle compared to the right ( see Figure 19.8 ) . Although the ventricles on the right and left sides pump the same amount of blood per contraction , the muscle of the left ventricle is much thicker and better developed than that of the right ventricle . The middle and thickest layer is the myocardium , made largely of cardiac muscle cells . The wall of the heart is composed of three layers of unequal thickness . From superficial to deep , these are the epicardium , the myocardium , and the endocardium ( see Figure 19.5 ) .", "question": { "cloze_format": "The myocardium would be the thickest in the ________.", "normal_format": "In what would the myocardium be the thickest?", "question_choices": [ "left atrium", "left ventricle", "right atrium", "right ventricle" ], "question_id": "fs-id2300602", "question_text": "The myocardium would be the thickest in the ________." }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 2, "ans_text": "atrioventricular septum" }, "bloom": null, "hl_context": "<hl> The septum between the atria and ventricles is known as the atrioventricular septum . <hl> <hl> It is marked by the presence of four openings that allow blood to move from the atria into the ventricles and from the ventricles into the pulmonary trunk and aorta . <hl> Located in each of these openings between the atria and ventricles is a valve , a specialized structure that ensures one-way flow of blood . The valves between the atria and ventricles are known generically as atrioventricular valves . The valves at the openings that lead to the pulmonary trunk and aorta are known generically as semilunar valves . The interventricular septum is visible in Figure 19.9 . In this figure , the atrioventricular septum has been removed to better show the bicuspid and tricuspid valves ; the interatrial septum is not visible , since its location is covered by the aorta and pulmonary trunk . Since these openings and valves structurally weaken the atrioventricular septum , the remaining tissue is heavily reinforced with dense connective tissue called the cardiac skeleton , or skeleton of the heart . It includes four rings that surround the openings between the atria and ventricles , and the openings to the pulmonary trunk and aorta , and serve as the point of attachment for the heart valves . The cardiac skeleton also provides an important boundary in the heart electrical conduction system .", "hl_sentences": "The septum between the atria and ventricles is known as the atrioventricular septum . It is marked by the presence of four openings that allow blood to move from the atria into the ventricles and from the ventricles into the pulmonary trunk and aorta .", "question": { "cloze_format": "The septum in which it is normal to find openings in the adult is the ___.", "normal_format": "In which septum is it normal to find openings in the adult?", "question_choices": [ "interatrial septum", "interventricular septum", "atrioventricular septum", "all of the above" ], "question_id": "fs-id1795973", "question_text": "In which septum is it normal to find openings in the adult?" }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 2, "ans_text": "Only cardiac muscle is capable of autorhythmicity" }, "bloom": "1", "hl_context": "<hl> Recall that cardiac muscle shares a few characteristics with both skeletal muscle and smooth muscle , but it has some unique properties of its own . <hl> Not the least of these exceptional properties is its ability to initiate an electrical potential at a fixed rate that spreads rapidly from cell to cell to trigger the contractile mechanism . <hl> This property is known as autorhythmicity . <hl> Neither smooth nor skeletal muscle can do this . Even though cardiac muscle has autorhythmicity , heart rate is modulated by the endocrine and nervous systems .", "hl_sentences": "Recall that cardiac muscle shares a few characteristics with both skeletal muscle and smooth muscle , but it has some unique properties of its own . This property is known as autorhythmicity .", "question": { "cloze_format": "It is unique to cardiac muscle cells that ___.", "normal_format": "Which of the following is unique to cardiac muscle cells?", "question_choices": [ "Only cardiac muscle contains a sarcoplasmic reticulum.", "Only cardiac muscle has gap junctions.", "Only cardiac muscle is capable of autorhythmicity", "Only cardiac muscle has a high concentration of mitochondria." ], "question_id": "fs-id2481331", "question_text": "Which of the following is unique to cardiac muscle cells?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 3, "ans_text": "calcium" }, "bloom": "1", "hl_context": "<hl> Calcium ions play two critical roles in the physiology of cardiac muscle . <hl> <hl> Their influx through slow calcium channels accounts for the prolonged plateau phase and absolute refractory period that enable cardiac muscle to function properly . <hl> Calcium ions also combine with the regulatory protein troponin in the troponin-tropomyosin complex ; this complex removes the inhibition that prevents the heads of the myosin molecules from forming cross bridges with the active sites on actin that provide the power stroke of contraction . This mechanism is virtually identical to that of skeletal muscle . Approximately 20 percent of the calcium required for contraction is supplied by the influx of Ca 2 + during the plateau phase . The remaining Ca 2 + for contraction is released from storage in the sarcoplasmic reticulum .", "hl_sentences": "Calcium ions play two critical roles in the physiology of cardiac muscle . Their influx through slow calcium channels accounts for the prolonged plateau phase and absolute refractory period that enable cardiac muscle to function properly .", "question": { "cloze_format": "The ion of which the influx accounts for the plateau phase is ___.", "normal_format": "The influx of which ion accounts for the plateau phase?", "question_choices": [ "sodium", "potassium", "chloride", "calcium" ], "question_id": "fs-id2050334", "question_text": "The influx of which ion accounts for the plateau phase?" }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 3, "ans_text": "none of the above: atrial repolarization is masked by ventricular depolarization" }, "bloom": "1", "hl_context": "<hl> Contraction of the atria follows depolarization , represented by the P wave of the ECG . <hl> As the atrial muscles contract from the superior portion of the atria toward the atrioventricular septum , pressure rises within the atria and blood is pumped into the ventricles through the open atrioventricular ( tricuspid , and mitral or bicuspid ) valves . At the start of atrial systole , the ventricles are normally filled with approximately 70 – 80 percent of their capacity due to inflow during diastole . Atrial contraction , also referred to as the “ atrial kick , ” contributes the remaining 20 – 30 percent of filling ( see Figure 19.27 ) . Atrial systole lasts approximately 100 ms and ends prior to ventricular systole , as the atrial muscle returns to diastole . There are five prominent points on the ECG : the P wave , the QRS complex , and the T wave . <hl> The small P wave represents the depolarization of the atria . <hl> The atria begin contracting approximately 25 ms after the start of the P wave . The large QRS complex represents the depolarization of the ventricles , which requires a much stronger electrical signal because of the larger size of the ventricular cardiac muscle . The ventricles begin to contract as the QRS reaches the peak of the R wave . Lastly , the T wave represents the repolarization of the ventricles . The repolarization of the atria occurs during the QRS complex , which masks it on an ECG .", "hl_sentences": "Contraction of the atria follows depolarization , represented by the P wave of the ECG . The small P wave represents the depolarization of the atria .", "question": { "cloze_format": "The portion of the ECG that corresponds to repolarization of the atria is the ___ .", "normal_format": "Which portion of the ECG corresponds to repolarization of the atria?", "question_choices": [ "P wave", "QRS complex", "T wave", "none of the above: atrial repolarization is masked by ventricular depolarization" ], "question_id": "fs-id2042928", "question_text": "Which portion of the ECG corresponds to repolarization of the atria?" }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 3, "ans_text": "Purkinje fibers" }, "bloom": "1", "hl_context": "The pattern of prepotential or spontaneous depolarization , followed by rapid depolarization and repolarization just described , are seen in the SA node and a few other conductive cells in the heart . Since the SA node is the pacemaker , it reaches threshold faster than any other component of the conduction system . It will initiate the impulses spreading to the other conducting cells . The SA node , without nervous or endocrine control , would initiate a heart impulse approximately 80 – 100 times per minute . Although each component of the conduction system is capable of generating its own impulse , the rate progressively slows as you proceed from the SA node to the Purkinje fibers . <hl> Without the SA node , the AV node would generate a heart rate of 40 – 60 beats per minute . <hl> <hl> If the AV node were blocked , the atrioventricular bundle would fire at a rate of approximately 30 – 40 impulses per minute . <hl> <hl> The bundle branches would have an inherent rate of 20 – 30 impulses per minute , and the Purkinje fibers would fire at 15 – 20 impulses per minute . <hl> While a few exceptionally trained aerobic athletes demonstrate resting heart rates in the range of 30 – 40 beats per minute ( the lowest recorded figure is 28 beats per minute for Miguel Indurain , a cyclist ) , for most individuals , rates lower than 50 beats per minute would indicate a condition called bradycardia . Depending upon the specific individual , as rates fall much below this level , the heart would be unable to maintain adequate flow of blood to vital tissues , initially resulting in decreasing loss of function across the systems , unconsciousness , and ultimately death .", "hl_sentences": "Without the SA node , the AV node would generate a heart rate of 40 – 60 beats per minute . If the AV node were blocked , the atrioventricular bundle would fire at a rate of approximately 30 – 40 impulses per minute . The bundle branches would have an inherent rate of 20 – 30 impulses per minute , and the Purkinje fibers would fire at 15 – 20 impulses per minute .", "question": { "cloze_format": "The component of the heart conduction system that would have the slowest rate of firing is the ___.", "normal_format": "Which component of the heart conduction system would have the slowest rate of firing?", "question_choices": [ "atrioventricular node", "atrioventricular bundle", "bundle branches", "Purkinje fibers" ], "question_id": "fs-id2060782", "question_text": "Which component of the heart conduction system would have the slowest rate of firing?" }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 3, "ans_text": "isovolumic contraction" }, "bloom": "1", "hl_context": "<hl> Initially , as the muscles in the ventricle contract , the pressure of the blood within the chamber rises , but it is not yet high enough to open the semilunar ( pulmonary and aortic ) valves and be ejected from the heart . <hl> <hl> However , blood pressure quickly rises above that of the atria that are now relaxed and in diastole . <hl> <hl> This increase in pressure causes blood to flow back toward the atria , closing the tricuspid and mitral valves . <hl> <hl> Since blood is not being ejected from the ventricles at this early stage , the volume of blood within the chamber remains constant . <hl> <hl> Consequently , this initial phase of ventricular systole is known as isovolumic contraction , also called isovolumetric contraction ( see Figure 19.27 ) . <hl>", "hl_sentences": "Initially , as the muscles in the ventricle contract , the pressure of the blood within the chamber rises , but it is not yet high enough to open the semilunar ( pulmonary and aortic ) valves and be ejected from the heart . However , blood pressure quickly rises above that of the atria that are now relaxed and in diastole . This increase in pressure causes blood to flow back toward the atria , closing the tricuspid and mitral valves . Since blood is not being ejected from the ventricles at this early stage , the volume of blood within the chamber remains constant . Consequently , this initial phase of ventricular systole is known as isovolumic contraction , also called isovolumetric contraction ( see Figure 19.27 ) .", "question": { "cloze_format": "The cardiac cycle consists of a distinct relaxation and contraction phase. The term that is typically used to refer ventricular contraction while no blood is being ejected is ___.", "normal_format": "The cardiac cycle consists of a distinct relaxation and contraction phase. Which term is typically used to refer ventricular contraction while no blood is being ejected?", "question_choices": [ "systole", "diastole", "quiescent", "isovolumic contraction" ], "question_id": "fs-id2001918", "question_text": "The cardiac cycle consists of a distinct relaxation and contraction phase. Which term is typically used to refer ventricular contraction while no blood is being ejected?" }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 1, "ans_text": "atrial diastole" }, "bloom": "1", "hl_context": "Contraction of the atria follows depolarization , represented by the P wave of the ECG . <hl> As the atrial muscles contract from the superior portion of the atria toward the atrioventricular septum , pressure rises within the atria and blood is pumped into the ventricles through the open atrioventricular ( tricuspid , and mitral or bicuspid ) valves . <hl> <hl> At the start of atrial systole , the ventricles are normally filled with approximately 70 – 80 percent of their capacity due to inflow during diastole . <hl> Atrial contraction , also referred to as the “ atrial kick , ” contributes the remaining 20 – 30 percent of filling ( see Figure 19.27 ) . Atrial systole lasts approximately 100 ms and ends prior to ventricular systole , as the atrial muscle returns to diastole .", "hl_sentences": "As the atrial muscles contract from the superior portion of the atria toward the atrioventricular septum , pressure rises within the atria and blood is pumped into the ventricles through the open atrioventricular ( tricuspid , and mitral or bicuspid ) valves . At the start of atrial systole , the ventricles are normally filled with approximately 70 – 80 percent of their capacity due to inflow during diastole .", "question": { "cloze_format": "Most blood enters the ventricle during ________.", "normal_format": "During what do most blood enter the ventricle?", "question_choices": [ "atrial systole", "atrial diastole", "ventricular systole", "isovolumic contraction" ], "question_id": "fs-id2321229", "question_text": "Most blood enters the ventricle during ________." }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 2, "ans_text": "closing of the atrioventricular valves" }, "bloom": null, "hl_context": "<hl> In a normal , healthy heart , there are only two audible heart sounds : S 1 and S 2 . <hl> <hl> S 1 is the sound created by the closing of the atrioventricular valves during ventricular contraction and is normally described as a “ lub , ” or first heart sound . <hl> The second heart sound , S 2 , is the sound of the closing of the semilunar valves during ventricular diastole and is described as a “ dub ” ( Figure 19.29 ) . In both cases , as the valves close , the openings within the atrioventricular septum guarded by the valves will become reduced , and blood flow through the opening will become more turbulent until the valves are fully closed . There is a third heart sound , S 3 , but it is rarely heard in healthy individuals . It may be the sound of blood flowing into the atria , or blood sloshing back and forth in the ventricle , or even tensing of the chordae tendineae . S 3 may be heard in youth , some athletes , and pregnant women . If the sound is heard later in life , it may indicate congestive heart failure , warranting further tests . Some cardiologists refer to the collective S 1 , S 2 , and S 3 sounds as the “ Kentucky gallop , ” because they mimic those produced by a galloping horse . The fourth heart sound , S 4 , results from the contraction of the atria pushing blood into a stiff or hypertrophic ventricle , indicating failure of the left ventricle . S 4 occurs prior to S 1 and the collective sounds S 4 , S 1 , and S 2 are referred to by some cardiologists as the “ Tennessee gallop , ” because of their similarity to the sound produced by a galloping horse with a different gait . A few individuals may have both S 3 and S 4 , and this combined sound is referred to as S 7 .", "hl_sentences": "In a normal , healthy heart , there are only two audible heart sounds : S 1 and S 2 . S 1 is the sound created by the closing of the atrioventricular valves during ventricular contraction and is normally described as a “ lub , ” or first heart sound .", "question": { "cloze_format": "The ___ is the portion of the cardiac cycle that the first heart sound represents.", "normal_format": "The first heart sound represents which portion of the cardiac cycle?", "question_choices": [ "atrial systole", "ventricular systole", "closing of the atrioventricular valves", "closing of the semilunar valves" ], "question_id": "fs-id2672256", "question_text": "The first heart sound represents which portion of the cardiac cycle?" }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 1, "ans_text": "ventricular repolarization" }, "bloom": "1", "hl_context": "<hl> Ventricular relaxation , or diastole , follows repolarization of the ventricles and is represented by the T wave of the ECG . <hl> It too is divided into two distinct phases and lasts approximately 430 ms .", "hl_sentences": "Ventricular relaxation , or diastole , follows repolarization of the ventricles and is represented by the T wave of the ECG .", "question": { "cloze_format": "Ventricular relaxation immediately follows ________.", "normal_format": "What does ventricular relaxation immediately follow?", "question_choices": [ "atrial depolarization", "ventricular repolarization", "ventricular depolarization", "atrial repolarization" ], "question_id": "fs-id2060926", "question_text": "Ventricular relaxation immediately follows ________." }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 1, "ans_text": "afterload" }, "bloom": "1", "hl_context": "<hl> Afterload refers to the tension that the ventricles must develop to pump blood effectively against the resistance in the vascular system . <hl> <hl> Any condition that increases resistance requires a greater afterload to force open the semilunar valves and pump the blood . <hl> Damage to the valves , such as stenosis , which makes them harder to open will also increase afterload . Any decrease in resistance decreases the afterload . Figure 19.34 summarizes the major factors influencing SV , Figure 19.35 summarizes the major factors influencing CO , and Table 19.3 and Table 19.4 summarize cardiac responses to increased and decreased blood flow and pressure in order to restore homeostasis . Many of the same factors that regulate HR also impact cardiac function by altering SV . While a number of variables are involved , SV is ultimately dependent upon the difference between EDV and ESV . <hl> The three primary factors to consider are preload , or the stretch on the ventricles prior to contraction ; the contractility , or the force or strength of the contraction itself ; and afterload , the force the ventricles must generate to pump blood against the resistance in the vessels . <hl> These factors are summarized in Table 19.1 and Table 19.2 .", "hl_sentences": "Afterload refers to the tension that the ventricles must develop to pump blood effectively against the resistance in the vascular system . Any condition that increases resistance requires a greater afterload to force open the semilunar valves and pump the blood . The three primary factors to consider are preload , or the stretch on the ventricles prior to contraction ; the contractility , or the force or strength of the contraction itself ; and afterload , the force the ventricles must generate to pump blood against the resistance in the vessels .", "question": { "cloze_format": "The force the heart must overcome to pump blood is known as ________.", "normal_format": "What is the force the heart must overcome to pump blood?", "question_choices": [ "preload", "afterload", "cardiac output", "stroke volume" ], "question_id": "fs-id2187635", "question_text": "The force the heart must overcome to pump blood is known as ________." }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 0, "ans_text": "medulla oblongata" }, "bloom": "1", "hl_context": "<hl> Nervous control over HR is centralized within the two paired cardiovascular centers of the medulla oblongata ( Figure 19.32 ) . <hl> The cardioaccelerator regions stimulate activity via sympathetic stimulation of the cardioaccelerator nerves , and the cardioinhibitory centers decrease heart activity via parasympathetic stimulation as one component of the vagus nerve , cranial nerve X . During rest , both centers provide slight stimulation to the heart , contributing to autonomic tone . This is a similar concept to tone in skeletal muscles . Normally , vagal stimulation predominates as , left unregulated , the SA node would initiate a sinus rhythm of approximately 100 bpm .", "hl_sentences": "Nervous control over HR is centralized within the two paired cardiovascular centers of the medulla oblongata ( Figure 19.32 ) .", "question": { "cloze_format": "The area of the brain in which the cardiovascular centers are located is the ___.", "normal_format": "The cardiovascular centers are located in which area of the brain?", "question_choices": [ "medulla oblongata", "pons", "mesencephalon (midbrain)", "cerebrum" ], "question_id": "fs-id2161526", "question_text": "The cardiovascular centers are located in which area of the brain?" }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 1, "ans_text": "It decreases." }, "bloom": "3", "hl_context": "Initially , physiological conditions that cause HR to increase also trigger an increase in SV . During exercise , the rate of blood returning to the heart increases . However as the HR rises , there is less time spent in diastole and consequently less time for the ventricles to fill with blood . Even though there is less filling time , SV will initially remain high . However , as HR continues to increase , SV gradually decreases due to decreased filling time . CO will initially stabilize as the increasing HR compensates for the decreasing SV , but at very high rates , CO will eventually decrease as increasing rates are no longer able to compensate for the decreasing SV . Consider this phenomenon in a healthy young individual . Initially , as HR increases from resting to approximately 120 bpm , CO will rise . As HR increases from 120 to 160 bpm , CO remains stable , since the increase in rate is offset by decreasing ventricular filling time and , consequently , SV . <hl> As HR continues to rise above 160 bpm , CO actually decreases as SV falls faster than HR increases . <hl> So although aerobic exercises are critical to maintain the health of the heart , individuals are cautioned to monitor their HR to ensure they stay within the target heart rate range of between 120 and 160 bpm , so CO is maintained . The target HR is loosely defined as the range in which both the heart and lungs receive the maximum benefit from the aerobic workout and is dependent upon age . <hl> Cardiac output ( CO ) is a measurement of the amount of blood pumped by each ventricle in one minute . <hl> <hl> To calculate this value , multiply stroke volume ( SV ) , the amount of blood pumped by each ventricle , by heart rate ( HR ) , in contractions per minute ( or beats per minute , bpm ) . <hl> It can be represented mathematically by the following equation :", "hl_sentences": "As HR continues to rise above 160 bpm , CO actually decreases as SV falls faster than HR increases . Cardiac output ( CO ) is a measurement of the amount of blood pumped by each ventricle in one minute . To calculate this value , multiply stroke volume ( SV ) , the amount of blood pumped by each ventricle , by heart rate ( HR ) , in contractions per minute ( or beats per minute , bpm ) .", "question": { "cloze_format": "In a healthy young adult, when heart rate increases above 160 bpm, the effect on the cardiac output is that ___.", "normal_format": "In a healthy young adult, what happens to cardiac output when heart rate increases above 160 bpm?", "question_choices": [ "It increases.", "It decreases.", "It remains constant.", "There is no way to predict." ], "question_id": "fs-id2049139", "question_text": "In a healthy young adult, what happens to cardiac output when heart rate increases above 160 bpm?" }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 3, "ans_text": "heart" }, "bloom": "1", "hl_context": "<hl> The human heart is the first functional organ to develop . <hl> It begins beating and pumping blood around day 21 or 22 , a mere three weeks after fertilization . This emphasizes the critical nature of the heart in distributing blood through the vessels and the vital exchange of nutrients , oxygen , and wastes both to and from the developing baby . The critical early development of the heart is reflected by the prominent heart bulge that appears on the anterior surface of the embryo .", "hl_sentences": "The human heart is the first functional organ to develop .", "question": { "cloze_format": "The earliest organ to form and begin function within the developing human is the ________.", "normal_format": "What is the earliest organ to form and begin function within the developing human?", "question_choices": [ "brain", "stomach", "lungs", "heart" ], "question_id": "fs-id1532146", "question_text": "The earliest organ to form and begin function within the developing human is the ________." }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 2, "ans_text": "mesoderm" }, "bloom": "1", "hl_context": "The heart forms from an embryonic tissue called mesoderm around 18 to 19 days after fertilization . <hl> Mesoderm is one of the three primary germ layers that differentiates early in development that collectively gives rise to all subsequent tissues and organs . <hl> The heart begins to develop near the head of the embryo in a region known as the cardiogenic area . Following chemical signals called factors from the underlying endoderm ( another of the three primary germ layers ) , the cardiogenic area begins to form two strands called the cardiogenic cords ( Figure 19.36 ) . As the cardiogenic cords develop , a lumen rapidly develops within them . At this point , they are referred to as endocardial tubes . The two tubes migrate together and fuse to form a single primitive heart tube . The primitive heart tube quickly forms five distinct regions . From head to tail , these include the truncus arteriosus , bulbus cordis , primitive ventricle , primitive atrium , and the sinus venosus . Initially , all venous blood flows into the sinus venosus , and contractions propel the blood from tail to head , or from the sinus venosus to the truncus arteriosus . This is a very different pattern from that of an adult .", "hl_sentences": "Mesoderm is one of the three primary germ layers that differentiates early in development that collectively gives rise to all subsequent tissues and organs .", "question": { "cloze_format": "Of the three germ layers that give rise to all adult tissues and organs, the ___ gives rise to the heart.", "normal_format": "Of the three germ layers that give rise to all adult tissues and organs, which gives rise to the heart?", "question_choices": [ "ectoderm", "endoderm", "mesoderm", "placenta" ], "question_id": "fs-id1883900", "question_text": "Of the three germ layers that give rise to all adult tissues and organs, which gives rise to the heart?" }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 0, "ans_text": "bulbus cordis" }, "bloom": "1", "hl_context": "<hl> The five regions of the primitive heart tube develop into recognizable structures in a fully developed heart . <hl> The truncus arteriosus will eventually divide and give rise to the ascending aorta and pulmonary trunk . <hl> The bulbus cordis develops into the right ventricle . <hl> The primitive ventricle forms the left ventricle . The primitive atrium becomes the anterior portions of both the right and left atria , and the two auricles . The sinus venosus develops into the posterior portion of the right atrium , the SA node , and the coronary sinus .", "hl_sentences": "The five regions of the primitive heart tube develop into recognizable structures in a fully developed heart . The bulbus cordis develops into the right ventricle .", "question": { "cloze_format": "The primitive area of the heart that will give rise to the right ventricle is the ___.", "normal_format": "Which primitive area of the heart will give rise to the right ventricle?", "question_choices": [ "bulbus cordis", "primitive ventricle", "sinus venosus", "truncus arteriosus" ], "question_id": "fs-id2189685", "question_text": "Which primitive area of the heart will give rise to the right ventricle?" }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 3, "ans_text": "truncus arteriosus" }, "bloom": "1", "hl_context": "The five regions of the primitive heart tube develop into recognizable structures in a fully developed heart . <hl> The truncus arteriosus will eventually divide and give rise to the ascending aorta and pulmonary trunk . <hl> The bulbus cordis develops into the right ventricle . The primitive ventricle forms the left ventricle . The primitive atrium becomes the anterior portions of both the right and left atria , and the two auricles . The sinus venosus develops into the posterior portion of the right atrium , the SA node , and the coronary sinus .", "hl_sentences": "The truncus arteriosus will eventually divide and give rise to the ascending aorta and pulmonary trunk .", "question": { "cloze_format": "The primitive heart structure the pulmonary trunk and aorta are derived from is the ___.", "normal_format": "The pulmonary trunk and aorta are derived from which primitive heart structure?", "question_choices": [ "bulbus cordis", "primitive ventricle", "sinus venosus", "truncus arteriosus" ], "question_id": "fs-id1846332", "question_text": "The pulmonary trunk and aorta are derived from which primitive heart structure?" }, "references_are_paraphrase": 0 } ]
19
19.1 Heart Anatomy Learning Objectives By the end of this section, you will be able to: Describe the location and position of the heart within the body cavity Describe the internal and external anatomy of the heart Identify the tissue layers of the heart Relate the structure of the heart to its function as a pump Compare systemic circulation to pulmonary circulation Identify the veins and arteries of the coronary circulation system Trace the pathway of oxygenated and deoxygenated blood thorough the chambers of the heart The vital importance of the heart is obvious. If one assumes an average rate of contraction of 75 contractions per minute, a human heart would contract approximately 108,000 times in one day, more than 39 million times in one year, and nearly 3 billion times during a 75-year lifespan. Each of the major pumping chambers of the heart ejects approximately 70 mL blood per contraction in a resting adult. This would be equal to 5.25 liters of fluid per minute and approximately 14,000 liters per day. Over one year, that would equal 10,000,000 liters or 2.6 million gallons of blood sent through roughly 60,000 miles of vessels. In order to understand how that happens, it is necessary to understand the anatomy and physiology of the heart. Location of the Heart The human heart is located within the thoracic cavity, medially between the lungs in the space known as the mediastinum. Figure 19.2 shows the position of the heart within the thoracic cavity. Within the mediastinum, the heart is separated from the other mediastinal structures by a tough membrane known as the pericardium, or pericardial sac, and sits in its own space called the pericardial cavity . The dorsal surface of the heart lies near the bodies of the vertebrae, and its anterior surface sits deep to the sternum and costal cartilages. The great veins, the superior and inferior venae cavae, and the great arteries, the aorta and pulmonary trunk, are attached to the superior surface of the heart, called the base. The base of the heart is located at the level of the third costal cartilage, as seen in Figure 19.2 . The inferior tip of the heart, the apex, lies just to the left of the sternum between the junction of the fourth and fifth ribs near their articulation with the costal cartilages. The right side of the heart is deflected anteriorly, and the left side is deflected posteriorly. It is important to remember the position and orientation of the heart when placing a stethoscope on the chest of a patient and listening for heart sounds, and also when looking at images taken from a midsagittal perspective. The slight deviation of the apex to the left is reflected in a depression in the medial surface of the inferior lobe of the left lung, called the cardiac notch . Everyday Connection CPR The position of the heart in the torso between the vertebrae and sternum (see Figure 19.2 for the position of the heart within the thorax) allows for individuals to apply an emergency technique known as cardiopulmonary resuscitation (CPR) if the heart of a patient should stop. By applying pressure with the flat portion of one hand on the sternum in the area between the line at T4 and T9 ( Figure 19.3 ), it is possible to manually compress the blood within the heart enough to push some of the blood within it into the pulmonary and systemic circuits. This is particularly critical for the brain, as irreversible damage and death of neurons occur within minutes of loss of blood flow. Current standards call for compression of the chest at least 5 cm deep and at a rate of 100 compressions per minute, a rate equal to the beat in “Staying Alive,” recorded in 1977 by the Bee Gees. If you are unfamiliar with this song, a version is available on www.youtube.com. At this stage, the emphasis is on performing high-quality chest compressions, rather than providing artificial respiration. CPR is generally performed until the patient regains spontaneous contraction or is declared dead by an experienced healthcare professional. When performed by untrained or overzealous individuals, CPR can result in broken ribs or a broken sternum, and can inflict additional severe damage on the patient. It is also possible, if the hands are placed too low on the sternum, to manually drive the xiphoid process into the liver, a consequence that may prove fatal for the patient. Proper training is essential. This proven life-sustaining technique is so valuable that virtually all medical personnel as well as concerned members of the public should be certified and routinely recertified in its application. CPR courses are offered at a variety of locations, including colleges, hospitals, the American Red Cross, and some commercial companies. They normally include practice of the compression technique on a mannequin. Interactive Link Visit the American Heart Association website to help locate a course near your home in the United States. There are also many other national and regional heart associations that offer the same service, depending upon the location. Shape and Size of the Heart The shape of the heart is similar to a pinecone, rather broad at the superior surface and tapering to the apex (see Figure 19.2 ). A typical heart is approximately the size of your fist: 12 cm (5 in) in length, 8 cm (3.5 in) wide, and 6 cm (2.5 in) in thickness. Given the size difference between most members of the sexes, the weight of a female heart is approximately 250–300 grams (9 to 11 ounces), and the weight of a male heart is approximately 300–350 grams (11 to 12 ounces). The heart of a well-trained athlete, especially one specializing in aerobic sports, can be considerably larger than this. Cardiac muscle responds to exercise in a manner similar to that of skeletal muscle. That is, exercise results in the addition of protein myofilaments that increase the size of the individual cells without increasing their numbers, a concept called hypertrophy. Hearts of athletes can pump blood more effectively at lower rates than those of nonathletes. Enlarged hearts are not always a result of exercise; they can result from pathologies, such as hypertrophic cardiomyopathy . The cause of an abnormally enlarged heart muscle is unknown, but the condition is often undiagnosed and can cause sudden death in apparently otherwise healthy young people. Chambers and Circulation through the Heart The human heart consists of four chambers: The left side and the right side each have one atrium and one ventricle . Each of the upper chambers, the right atrium (plural = atria) and the left atrium, acts as a receiving chamber and contracts to push blood into the lower chambers, the right ventricle and the left ventricle. The ventricles serve as the primary pumping chambers of the heart, propelling blood to the lungs or to the rest of the body. There are two distinct but linked circuits in the human circulation called the pulmonary and systemic circuits. Although both circuits transport blood and everything it carries, we can initially view the circuits from the point of view of gases. The pulmonary circuit transports blood to and from the lungs, where it picks up oxygen and delivers carbon dioxide for exhalation. The systemic circuit transports oxygenated blood to virtually all of the tissues of the body and returns relatively deoxygenated blood and carbon dioxide to the heart to be sent back to the pulmonary circulation. The right ventricle pumps deoxygenated blood into the pulmonary trunk , which leads toward the lungs and bifurcates into the left and right pulmonary arteries . These vessels in turn branch many times before reaching the pulmonary capillaries , where gas exchange occurs: Carbon dioxide exits the blood and oxygen enters. The pulmonary trunk arteries and their branches are the only arteries in the post-natal body that carry relatively deoxygenated blood. Highly oxygenated blood returning from the pulmonary capillaries in the lungs passes through a series of vessels that join together to form the pulmonary veins —the only post-natal veins in the body that carry highly oxygenated blood. The pulmonary veins conduct blood into the left atrium, which pumps the blood into the left ventricle, which in turn pumps oxygenated blood into the aorta and on to the many branches of the systemic circuit. Eventually, these vessels will lead to the systemic capillaries, where exchange with the tissue fluid and cells of the body occurs. In this case, oxygen and nutrients exit the systemic capillaries to be used by the cells in their metabolic processes, and carbon dioxide and waste products will enter the blood. The blood exiting the systemic capillaries is lower in oxygen concentration than when it entered. The capillaries will ultimately unite to form venules, joining to form ever-larger veins, eventually flowing into the two major systemic veins, the superior vena cava and the inferior vena cava , which return blood to the right atrium. The blood in the superior and inferior venae cavae flows into the right atrium, which pumps blood into the right ventricle. This process of blood circulation continues as long as the individual remains alive. Understanding the flow of blood through the pulmonary and systemic circuits is critical to all health professions ( Figure 19.4 ). Membranes, Surface Features, and Layers Our exploration of more in-depth heart structures begins by examining the membrane that surrounds the heart, the prominent surface features of the heart, and the layers that form the wall of the heart. Each of these components plays its own unique role in terms of function. Membranes The membrane that directly surrounds the heart and defines the pericardial cavity is called the pericardium or pericardial sac . It also surrounds the “roots” of the major vessels, or the areas of closest proximity to the heart. The pericardium, which literally translates as “around the heart,” consists of two distinct sublayers: the sturdy outer fibrous pericardium and the inner serous pericardium. The fibrous pericardium is made of tough, dense connective tissue that protects the heart and maintains its position in the thorax. The more delicate serous pericardium consists of two layers: the parietal pericardium, which is fused to the fibrous pericardium, and an inner visceral pericardium, or epicardium , which is fused to the heart and is part of the heart wall. The pericardial cavity, filled with lubricating serous fluid, lies between the epicardium and the pericardium. In most organs within the body, visceral serous membranes such as the epicardium are microscopic. However, in the case of the heart, it is not a microscopic layer but rather a macroscopic layer, consisting of a simple squamous epithelium called a mesothelium , reinforced with loose, irregular, or areolar connective tissue that attaches to the pericardium. This mesothelium secretes the lubricating serous fluid that fills the pericardial cavity and reduces friction as the heart contracts. Figure 19.5 illustrates the pericardial membrane and the layers of the heart. Disorders of the... Heart: Cardiac Tamponade If excess fluid builds within the pericardial space, it can lead to a condition called cardiac tamponade, or pericardial tamponade. With each contraction of the heart, more fluid—in most instances, blood—accumulates within the pericardial cavity. In order to fill with blood for the next contraction, the heart must relax. However, the excess fluid in the pericardial cavity puts pressure on the heart and prevents full relaxation, so the chambers within the heart contain slightly less blood as they begin each heart cycle. Over time, less and less blood is ejected from the heart. If the fluid builds up slowly, as in hypothyroidism, the pericardial cavity may be able to expand gradually to accommodate this extra volume. Some cases of fluid in excess of one liter within the pericardial cavity have been reported. Rapid accumulation of as little as 100 mL of fluid following trauma may trigger cardiac tamponade. Other common causes include myocardial rupture, pericarditis, cancer, or even cardiac surgery. Removal of this excess fluid requires insertion of drainage tubes into the pericardial cavity. Premature removal of these drainage tubes, for example, following cardiac surgery, or clot formation within these tubes are causes of this condition. Untreated, cardiac tamponade can lead to death. Surface Features of the Heart Inside the pericardium, the surface features of the heart are visible, including the four chambers. There is a superficial leaf-like extension of the atria near the superior surface of the heart, one on each side, called an auricle —a name that means “ear like”—because its shape resembles the external ear of a human ( Figure 19.6 ). Auricles are relatively thin-walled structures that can fill with blood and empty into the atria or upper chambers of the heart. You may also hear them referred to as atrial appendages. Also prominent is a series of fat-filled grooves, each of which is known as a sulcus (plural = sulci), along the superior surfaces of the heart. Major coronary blood vessels are located in these sulci. The deep coronary sulcus is located between the atria and ventricles. Located between the left and right ventricles are two additional sulci that are not as deep as the coronary sulcus. The anterior interventricular sulcus is visible on the anterior surface of the heart, whereas the posterior interventricular sulcus is visible on the posterior surface of the heart. Figure 19.6 illustrates anterior and posterior views of the surface of the heart. Layers The wall of the heart is composed of three layers of unequal thickness. From superficial to deep, these are the epicardium, the myocardium, and the endocardium (see Figure 19.5 ). The outermost layer of the wall of the heart is also the innermost layer of the pericardium, the epicardium, or the visceral pericardium discussed earlier. The middle and thickest layer is the myocardium , made largely of cardiac muscle cells. It is built upon a framework of collagenous fibers, plus the blood vessels that supply the myocardium and the nerve fibers that help regulate the heart. It is the contraction of the myocardium that pumps blood through the heart and into the major arteries. The muscle pattern is elegant and complex, as the muscle cells swirl and spiral around the chambers of the heart. They form a figure 8 pattern around the atria and around the bases of the great vessels. Deeper ventricular muscles also form a figure 8 around the two ventricles and proceed toward the apex. More superficial layers of ventricular muscle wrap around both ventricles. This complex swirling pattern allows the heart to pump blood more effectively than a simple linear pattern would. Figure 19.7 illustrates the arrangement of muscle cells. Although the ventricles on the right and left sides pump the same amount of blood per contraction, the muscle of the left ventricle is much thicker and better developed than that of the right ventricle. In order to overcome the high resistance required to pump blood into the long systemic circuit, the left ventricle must generate a great amount of pressure. The right ventricle does not need to generate as much pressure, since the pulmonary circuit is shorter and provides less resistance. Figure 19.8 illustrates the differences in muscular thickness needed for each of the ventricles. The innermost layer of the heart wall, the endocardium , is joined to the myocardium with a thin layer of connective tissue. The endocardium lines the chambers where the blood circulates and covers the heart valves. It is made of simple squamous epithelium called endothelium , which is continuous with the endothelial lining of the blood vessels (see Figure 19.5 ). Once regarded as a simple lining layer, recent evidence indicates that the endothelium of the endocardium and the coronary capillaries may play active roles in regulating the contraction of the muscle within the myocardium. The endothelium may also regulate the growth patterns of the cardiac muscle cells throughout life, and the endothelins it secretes create an environment in the surrounding tissue fluids that regulates ionic concentrations and states of contractility. Endothelins are potent vasoconstrictors and, in a normal individual, establish a homeostatic balance with other vasoconstrictors and vasodilators. Internal Structure of the Heart Recall that the heart’s contraction cycle follows a dual pattern of circulation—the pulmonary and systemic circuits—because of the pairs of chambers that pump blood into the circulation. In order to develop a more precise understanding of cardiac function, it is first necessary to explore the internal anatomical structures in more detail. Septa of the Heart The word septum is derived from the Latin for “something that encloses;” in this case, a septum (plural = septa) refers to a wall or partition that divides the heart into chambers. The septa are physical extensions of the myocardium lined with endocardium. Located between the two atria is the interatrial septum . Normally in an adult heart, the interatrial septum bears an oval-shaped depression known as the fossa ovalis , a remnant of an opening in the fetal heart known as the foramen ovale . The foramen ovale allowed blood in the fetal heart to pass directly from the right atrium to the left atrium, allowing some blood to bypass the pulmonary circuit. Within seconds after birth, a flap of tissue known as the septum primum that previously acted as a valve closes the foramen ovale and establishes the typical cardiac circulation pattern. Between the two ventricles is a second septum known as the interventricular septum . Unlike the interatrial septum, the interventricular septum is normally intact after its formation during fetal development. It is substantially thicker than the interatrial septum, since the ventricles generate far greater pressure when they contract. The septum between the atria and ventricles is known as the atrioventricular septum . It is marked by the presence of four openings that allow blood to move from the atria into the ventricles and from the ventricles into the pulmonary trunk and aorta. Located in each of these openings between the atria and ventricles is a valve , a specialized structure that ensures one-way flow of blood. The valves between the atria and ventricles are known generically as atrioventricular valves . The valves at the openings that lead to the pulmonary trunk and aorta are known generically as semilunar valves . The interventricular septum is visible in Figure 19.9 . In this figure, the atrioventricular septum has been removed to better show the bicuspid and tricuspid valves; the interatrial septum is not visible, since its location is covered by the aorta and pulmonary trunk. Since these openings and valves structurally weaken the atrioventricular septum, the remaining tissue is heavily reinforced with dense connective tissue called the cardiac skeleton , or skeleton of the heart. It includes four rings that surround the openings between the atria and ventricles, and the openings to the pulmonary trunk and aorta, and serve as the point of attachment for the heart valves. The cardiac skeleton also provides an important boundary in the heart electrical conduction system. Disorders of the... Heart: Heart Defects One very common form of interatrial septum pathology is patent foramen ovale, which occurs when the septum primum does not close at birth, and the fossa ovalis is unable to fuse. The word patent is from the Latin root patens for “open.” It may be benign or asymptomatic, perhaps never being diagnosed, or in extreme cases, it may require surgical repair to close the opening permanently. As much as 20–25 percent of the general population may have a patent foramen ovale, but fortunately, most have the benign, asymptomatic version. Patent foramen ovale is normally detected by auscultation of a heart murmur (an abnormal heart sound) and confirmed by imaging with an echocardiogram. Despite its prevalence in the general population, the causes of patent ovale are unknown, and there are no known risk factors. In nonlife-threatening cases, it is better to monitor the condition than to risk heart surgery to repair and seal the opening. Coarctation of the aorta is a congenital abnormal narrowing of the aorta that is normally located at the insertion of the ligamentum arteriosum, the remnant of the fetal shunt called the ductus arteriosus. If severe, this condition drastically restricts blood flow through the primary systemic artery, which is life threatening. In some individuals, the condition may be fairly benign and not detected until later in life. Detectable symptoms in an infant include difficulty breathing, poor appetite, trouble feeding, or failure to thrive. In older individuals, symptoms include dizziness, fainting, shortness of breath, chest pain, fatigue, headache, and nosebleeds. Treatment involves surgery to resect (remove) the affected region or angioplasty to open the abnormally narrow passageway. Studies have shown that the earlier the surgery is performed, the better the chance of survival. A patent ductus arteriosus is a congenital condition in which the ductus arteriosus fails to close. The condition may range from severe to benign. Failure of the ductus arteriosus to close results in blood flowing from the higher pressure aorta into the lower pressure pulmonary trunk. This additional fluid moving toward the lungs increases pulmonary pressure and makes respiration difficult. Symptoms include shortness of breath (dyspnea), tachycardia, enlarged heart, a widened pulse pressure, and poor weight gain in infants. Treatments include surgical closure (ligation), manual closure using platinum coils or specialized mesh inserted via the femoral artery or vein, or nonsteroidal anti-inflammatory drugs to block the synthesis of prostaglandin E2, which maintains the vessel in an open position. If untreated, the condition can result in congestive heart failure. Septal defects are not uncommon in individuals and may be congenital or caused by various disease processes. Tetralogy of Fallot is a congenital condition that may also occur from exposure to unknown environmental factors; it occurs when there is an opening in the interventricular septum caused by blockage of the pulmonary trunk, normally at the pulmonary semilunar valve. This allows blood that is relatively low in oxygen from the right ventricle to flow into the left ventricle and mix with the blood that is relatively high in oxygen. Symptoms include a distinct heart murmur, low blood oxygen percent saturation, dyspnea or difficulty in breathing, polycythemia, broadening (clubbing) of the fingers and toes, and in children, difficulty in feeding or failure to grow and develop. It is the most common cause of cyanosis following birth. The term “tetralogy” is derived from the four components of the condition, although only three may be present in an individual patient: pulmonary infundibular stenosis (rigidity of the pulmonary valve), overriding aorta (the aorta is shifted above both ventricles), ventricular septal defect (opening), and right ventricular hypertrophy (enlargement of the right ventricle). Other heart defects may also accompany this condition, which is typically confirmed by echocardiography imaging. Tetralogy of Fallot occurs in approximately 400 out of one million live births. Normal treatment involves extensive surgical repair, including the use of stents to redirect blood flow and replacement of valves and patches to repair the septal defect, but the condition has a relatively high mortality. Survival rates are currently 75 percent during the first year of life; 60 percent by 4 years of age; 30 percent by 10 years; and 5 percent by 40 years. In the case of severe septal defects, including both tetralogy of Fallot and patent foramen ovale, failure of the heart to develop properly can lead to a condition commonly known as a “blue baby.” Regardless of normal skin pigmentation, individuals with this condition have an insufficient supply of oxygenated blood, which leads to cyanosis, a blue or purple coloration of the skin, especially when active. Septal defects are commonly first detected through auscultation, listening to the chest using a stethoscope. In this case, instead of hearing normal heart sounds attributed to the flow of blood and closing of heart valves, unusual heart sounds may be detected. This is often followed by medical imaging to confirm or rule out a diagnosis. In many cases, treatment may not be needed. Some common congenital heart defects are illustrated in Figure 19.10 . Right Atrium The right atrium serves as the receiving chamber for blood returning to the heart from the systemic circulation. The two major systemic veins, the superior and inferior venae cavae, and the large coronary vein called the coronary sinus that drains the heart myocardium empty into the right atrium. The superior vena cava drains blood from regions superior to the diaphragm: the head, neck, upper limbs, and the thoracic region. It empties into the superior and posterior portions of the right atrium. The inferior vena cava drains blood from areas inferior to the diaphragm: the lower limbs and abdominopelvic region of the body. It, too, empties into the posterior portion of the atria, but inferior to the opening of the superior vena cava. Immediately superior and slightly medial to the opening of the inferior vena cava on the posterior surface of the atrium is the opening of the coronary sinus. This thin-walled vessel drains most of the coronary veins that return systemic blood from the heart. The majority of the internal heart structures discussed in this and subsequent sections are illustrated in Figure 19.9 . While the bulk of the internal surface of the right atrium is smooth, the depression of the fossa ovalis is medial, and the anterior surface demonstrates prominent ridges of muscle called the pectinate muscles . The right auricle also has pectinate muscles. The left atrium does not have pectinate muscles except in the auricle. The atria receive venous blood on a nearly continuous basis, preventing venous flow from stopping while the ventricles are contracting. While most ventricular filling occurs while the atria are relaxed, they do demonstrate a contractile phase and actively pump blood into the ventricles just prior to ventricular contraction. The opening between the atrium and ventricle is guarded by the tricuspid valve. Right Ventricle The right ventricle receives blood from the right atrium through the tricuspid valve. Each flap of the valve is attached to strong strands of connective tissue, the chordae tendineae , literally “tendinous cords,” or sometimes more poetically referred to as “heart strings.” There are several chordae tendineae associated with each of the flaps. They are composed of approximately 80 percent collagenous fibers with the remainder consisting of elastic fibers and endothelium. They connect each of the flaps to a papillary muscle that extends from the inferior ventricular surface. There are three papillary muscles in the right ventricle, called the anterior, posterior, and septal muscles, which correspond to the three sections of the valves. When the myocardium of the ventricle contracts, pressure within the ventricular chamber rises. Blood, like any fluid, flows from higher pressure to lower pressure areas, in this case, toward the pulmonary trunk and the atrium. To prevent any potential backflow, the papillary muscles also contract, generating tension on the chordae tendineae. This prevents the flaps of the valves from being forced into the atria and regurgitation of the blood back into the atria during ventricular contraction. Figure 19.11 shows papillary muscles and chordae tendineae attached to the tricuspid valve. The walls of the ventricle are lined with trabeculae carneae , ridges of cardiac muscle covered by endocardium. In addition to these muscular ridges, a band of cardiac muscle, also covered by endocardium, known as the moderator band (see Figure 19.9 ) reinforces the thin walls of the right ventricle and plays a crucial role in cardiac conduction. It arises from the inferior portion of the interventricular septum and crosses the interior space of the right ventricle to connect with the inferior papillary muscle. When the right ventricle contracts, it ejects blood into the pulmonary trunk, which branches into the left and right pulmonary arteries that carry it to each lung. The superior surface of the right ventricle begins to taper as it approaches the pulmonary trunk. At the base of the pulmonary trunk is the pulmonary semilunar valve that prevents backflow from the pulmonary trunk. Left Atrium After exchange of gases in the pulmonary capillaries, blood returns to the left atrium high in oxygen via one of the four pulmonary veins. While the left atrium does not contain pectinate muscles, it does have an auricle that includes these pectinate ridges. Blood flows nearly continuously from the pulmonary veins back into the atrium, which acts as the receiving chamber, and from here through an opening into the left ventricle. Most blood flows passively into the heart while both the atria and ventricles are relaxed, but toward the end of the ventricular relaxation period, the left atrium will contract, pumping blood into the ventricle. This atrial contraction accounts for approximately 20 percent of ventricular filling. The opening between the left atrium and ventricle is guarded by the mitral valve. Left Ventricle Recall that, although both sides of the heart will pump the same amount of blood, the muscular layer is much thicker in the left ventricle compared to the right (see Figure 19.8 ). Like the right ventricle, the left also has trabeculae carneae, but there is no moderator band. The mitral valve is connected to papillary muscles via chordae tendineae. There are two papillary muscles on the left—the anterior and posterior—as opposed to three on the right. The left ventricle is the major pumping chamber for the systemic circuit; it ejects blood into the aorta through the aortic semilunar valve. Heart Valve Structure and Function A transverse section through the heart slightly above the level of the atrioventricular septum reveals all four heart valves along the same plane ( Figure 19.12 ). The valves ensure unidirectional blood flow through the heart. Between the right atrium and the right ventricle is the right atrioventricular valve , or tricuspid valve . It typically consists of three flaps, or leaflets, made of endocardium reinforced with additional connective tissue. The flaps are connected by chordae tendineae to the papillary muscles, which control the opening and closing of the valves. Emerging from the right ventricle at the base of the pulmonary trunk is the pulmonary semilunar valve, or the pulmonary valve ; it is also known as the pulmonic valve or the right semilunar valve. The pulmonary valve is comprised of three small flaps of endothelium reinforced with connective tissue. When the ventricle relaxes, the pressure differential causes blood to flow back into the ventricle from the pulmonary trunk. This flow of blood fills the pocket-like flaps of the pulmonary valve, causing the valve to close and producing an audible sound. Unlike the atrioventricular valves, there are no papillary muscles or chordae tendineae associated with the pulmonary valve. Located at the opening between the left atrium and left ventricle is the mitral valve , also called the bicuspid valve or the left atrioventricular valve . Structurally, this valve consists of two cusps, compared to the three cusps of the tricuspid valve. In a clinical setting, the valve is referred to as the mitral valve, rather than the bicuspid valve. The two cusps of the mitral valve are attached by chordae tendineae to two papillary muscles that project from the wall of the ventricle. At the base of the aorta is the aortic semilunar valve, or the aortic valve , which prevents backflow from the aorta. It normally is composed of three flaps. When the ventricle relaxes and blood attempts to flow back into the ventricle from the aorta, blood will fill the cusps of the valve, causing it to close and producing an audible sound. In Figure 19.13 a , the two atrioventricular valves are open and the two semilunar valves are closed. This occurs when both atria and ventricles are relaxed and when the atria contract to pump blood into the ventricles. Figure 19.13 b shows a frontal view. Although only the left side of the heart is illustrated, the process is virtually identical on the right. Figure 19.14 a shows the atrioventricular valves closed while the two semilunar valves are open. This occurs when the ventricles contract to eject blood into the pulmonary trunk and aorta. Closure of the two atrioventricular valves prevents blood from being forced back into the atria. This stage can be seen from a frontal view in Figure 19.14 b . When the ventricles begin to contract, pressure within the ventricles rises and blood flows toward the area of lowest pressure, which is initially in the atria. This backflow causes the cusps of the tricuspid and mitral (bicuspid) valves to close. These valves are tied down to the papillary muscles by chordae tendineae. During the relaxation phase of the cardiac cycle, the papillary muscles are also relaxed and the tension on the chordae tendineae is slight (see Figure 19.13 b ). However, as the myocardium of the ventricle contracts, so do the papillary muscles. This creates tension on the chordae tendineae (see Figure 19.14 b ), helping to hold the cusps of the atrioventricular valves in place and preventing them from being blown back into the atria. The aortic and pulmonary semilunar valves lack the chordae tendineae and papillary muscles associated with the atrioventricular valves. Instead, they consist of pocket-like folds of endocardium reinforced with additional connective tissue. When the ventricles relax and the change in pressure forces the blood toward the ventricles, the blood presses against these cusps and seals the openings. Interactive Link Visit this site to observe an echocardiogram of actual heart valves opening and closing. Although much of the heart has been “removed” from this gif loop so the chordae tendineae are not visible, why is their presence more critical for the atrioventricular valves (tricuspid and mitral) than the semilunar (aortic and pulmonary) valves? Disorders of the... Heart Valves When heart valves do not function properly, they are often described as incompetent and result in valvular heart disease, which can range from benign to lethal. Some of these conditions are congenital, that is, the individual was born with the defect, whereas others may be attributed to disease processes or trauma. Some malfunctions are treated with medications, others require surgery, and still others may be mild enough that the condition is merely monitored since treatment might trigger more serious consequences. Valvular disorders are often caused by carditis, or inflammation of the heart. One common trigger for this inflammation is rheumatic fever, or scarlet fever, an autoimmune response to the presence of a bacterium, Streptococcus pyogenes , normally a disease of childhood. While any of the heart valves may be involved in valve disorders, mitral regurgitation is the most common, detected in approximately 2 percent of the population, and the pulmonary semilunar valve is the least frequently involved. When a valve malfunctions, the flow of blood to a region will often be disrupted. The resulting inadequate flow of blood to this region will be described in general terms as an insufficiency. The specific type of insufficiency is named for the valve involved: aortic insufficiency, mitral insufficiency, tricuspid insufficiency, or pulmonary insufficiency. If one of the cusps of the valve is forced backward by the force of the blood, the condition is referred to as a prolapsed valve. Prolapse may occur if the chordae tendineae are damaged or broken, causing the closure mechanism to fail. The failure of the valve to close properly disrupts the normal one-way flow of blood and results in regurgitation, when the blood flows backward from its normal path. Using a stethoscope, the disruption to the normal flow of blood produces a heart murmur. Stenosis is a condition in which the heart valves become rigid and may calcify over time. The loss of flexibility of the valve interferes with normal function and may cause the heart to work harder to propel blood through the valve, which eventually weakens the heart. Aortic stenosis affects approximately 2 percent of the population over 65 years of age, and the percentage increases to approximately 4 percent in individuals over 85 years. Occasionally, one or more of the chordae tendineae will tear or the papillary muscle itself may die as a component of a myocardial infarction (heart attack). In this case, the patient’s condition will deteriorate dramatically and rapidly, and immediate surgical intervention may be required. Auscultation, or listening to a patient’s heart sounds, is one of the most useful diagnostic tools, since it is proven, safe, and inexpensive. The term auscultation is derived from the Latin for “to listen,” and the technique has been used for diagnostic purposes as far back as the ancient Egyptians. Valve and septal disorders will trigger abnormal heart sounds. If a valvular disorder is detected or suspected, a test called an echocardiogram, or simply an “echo,” may be ordered. Echocardiograms are sonograms of the heart and can help in the diagnosis of valve disorders as well as a wide variety of heart pathologies. Interactive Link Visit this site for a free download, including excellent animations and audio of heart sounds. Career Connection Cardiologist Cardiologists are medical doctors that specialize in the diagnosis and treatment of diseases of the heart. After completing 4 years of medical school, cardiologists complete a three-year residency in internal medicine followed by an additional three or more years in cardiology. Following this 10-year period of medical training and clinical experience, they qualify for a rigorous two-day examination administered by the Board of Internal Medicine that tests their academic training and clinical abilities, including diagnostics and treatment. After successful completion of this examination, a physician becomes a board-certified cardiologist. Some board-certified cardiologists may be invited to become a Fellow of the American College of Cardiology (FACC). This professional recognition is awarded to outstanding physicians based upon merit, including outstanding credentials, achievements, and community contributions to cardiovascular medicine. Interactive Link Visit this site to learn more about cardiologists. Career Connection Cardiovascular Technologist/Technician Cardiovascular technologists/technicians are trained professionals who perform a variety of imaging techniques, such as sonograms or echocardiograms, used by physicians to diagnose and treat diseases of the heart. Nearly all of these positions require an associate degree, and these technicians earn a median salary of $49,410 as of May 2010, according to the U.S. Bureau of Labor Statistics. Growth within the field is fast, projected at 29 percent from 2010 to 2020. There is a considerable overlap and complementary skills between cardiac technicians and vascular technicians, and so the term cardiovascular technician is often used. Special certifications within the field require documenting appropriate experience and completing additional and often expensive certification examinations. These subspecialties include Certified Rhythm Analysis Technician (CRAT), Certified Cardiographic Technician (CCT), Registered Congenital Cardiac Sonographer (RCCS), Registered Cardiac Electrophysiology Specialist (RCES), Registered Cardiovascular Invasive Specialist (RCIS), Registered Cardiac Sonographer (RCS), Registered Vascular Specialist (RVS), and Registered Phlebology Sonographer (RPhS). Interactive Link Visit this site for more information on cardiovascular technologists/technicians. Coronary Circulation You will recall that the heart is a remarkable pump composed largely of cardiac muscle cells that are incredibly active throughout life. Like all other cells, a cardiomyocyte requires a reliable supply of oxygen and nutrients, and a way to remove wastes, so it needs a dedicated, complex, and extensive coronary circulation. And because of the critical and nearly ceaseless activity of the heart throughout life, this need for a blood supply is even greater than for a typical cell. However, coronary circulation is not continuous; rather, it cycles, reaching a peak when the heart muscle is relaxed and nearly ceasing while it is contracting. Coronary Arteries Coronary arteries supply blood to the myocardium and other components of the heart. The first portion of the aorta after it arises from the left ventricle gives rise to the coronary arteries. There are three dilations in the wall of the aorta just superior to the aortic semilunar valve. Two of these, the left posterior aortic sinus and anterior aortic sinus, give rise to the left and right coronary arteries, respectively. The third sinus, the right posterior aortic sinus, typically does not give rise to a vessel. Coronary vessel branches that remain on the surface of the artery and follow the sulci are called epicardial coronary arteries . The left coronary artery distributes blood to the left side of the heart, the left atrium and ventricle, and the interventricular septum. The circumflex artery arises from the left coronary artery and follows the coronary sulcus to the left. Eventually, it will fuse with the small branches of the right coronary artery. The larger anterior interventricular artery , also known as the left anterior descending artery (LAD), is the second major branch arising from the left coronary artery. It follows the anterior interventricular sulcus around the pulmonary trunk. Along the way it gives rise to numerous smaller branches that interconnect with the branches of the posterior interventricular artery, forming anastomoses. An anastomosis is an area where vessels unite to form interconnections that normally allow blood to circulate to a region even if there may be partial blockage in another branch. The anastomoses in the heart are very small. Therefore, this ability is somewhat restricted in the heart so a coronary artery blockage often results in death of the cells (myocardial infarction) supplied by the particular vessel. The right coronary artery proceeds along the coronary sulcus and distributes blood to the right atrium, portions of both ventricles, and the heart conduction system. Normally, one or more marginal arteries arise from the right coronary artery inferior to the right atrium. The marginal arteries supply blood to the superficial portions of the right ventricle. On the posterior surface of the heart, the right coronary artery gives rise to the posterior interventricular artery , also known as the posterior descending artery. It runs along the posterior portion of the interventricular sulcus toward the apex of the heart, giving rise to branches that supply the interventricular septum and portions of both ventricles. Figure 19.15 presents views of the coronary circulation from both the anterior and posterior views. Diseases of the... Heart: Myocardial Infarction Myocardial infarction (MI) is the formal term for what is commonly referred to as a heart attack. It normally results from a lack of blood flow (ischemia) and oxygen (hypoxia) to a region of the heart, resulting in death of the cardiac muscle cells. An MI often occurs when a coronary artery is blocked by the buildup of atherosclerotic plaque consisting of lipids, cholesterol and fatty acids, and white blood cells, primarily macrophages. It can also occur when a portion of an unstable atherosclerotic plaque travels through the coronary arterial system and lodges in one of the smaller vessels. The resulting blockage restricts the flow of blood and oxygen to the myocardium and causes death of the tissue. MIs may be triggered by excessive exercise, in which the partially occluded artery is no longer able to pump sufficient quantities of blood, or severe stress, which may induce spasm of the smooth muscle in the walls of the vessel. In the case of acute MI, there is often sudden pain beneath the sternum (retrosternal pain) called angina pectoris, often radiating down the left arm in males but not in female patients. Until this anomaly between the sexes was discovered, many female patients suffering MIs were misdiagnosed and sent home. In addition, patients typically present with difficulty breathing and shortness of breath (dyspnea), irregular heartbeat (palpations), nausea and vomiting, sweating (diaphoresis), anxiety, and fainting (syncope), although not all of these symptoms may be present. Many of the symptoms are shared with other medical conditions, including anxiety attacks and simple indigestion, so differential diagnosis is critical. It is estimated that between 22 and 64 percent of MIs present without any symptoms. An MI can be confirmed by examining the patient’s ECG, which frequently reveals alterations in the ST and Q components. Some classification schemes of MI are referred to as ST-elevated MI (STEMI) and non-elevated MI (non-STEMI). In addition, echocardiography or cardiac magnetic resonance imaging may be employed. Common blood tests indicating an MI include elevated levels of creatine kinase MB (an enzyme that catalyzes the conversion of creatine to phosphocreatine, consuming ATP) and cardiac troponin (the regulatory protein for muscle contraction), both of which are released by damaged cardiac muscle cells. Immediate treatments for MI are essential and include administering supplemental oxygen, aspirin that helps to break up clots, and nitroglycerine administered sublingually (under the tongue) to facilitate its absorption. Despite its unquestioned success in treatments and use since the 1880s, the mechanism of nitroglycerine is still incompletely understood but is believed to involve the release of nitric oxide, a known vasodilator, and endothelium-derived releasing factor, which also relaxes the smooth muscle in the tunica media of coronary vessels. Longer-term treatments include injections of thrombolytic agents such as streptokinase that dissolve the clot, the anticoagulant heparin, balloon angioplasty and stents to open blocked vessels, and bypass surgery to allow blood to pass around the site of blockage. If the damage is extensive, coronary replacement with a donor heart or coronary assist device, a sophisticated mechanical device that supplements the pumping activity of the heart, may be employed. Despite the attention, development of artificial hearts to augment the severely limited supply of heart donors has proven less than satisfactory but will likely improve in the future. MIs may trigger cardiac arrest, but the two are not synonymous. Important risk factors for MI include cardiovascular disease, age, smoking, high blood levels of the low-density lipoprotein (LDL, often referred to as “bad” cholesterol), low levels of high-density lipoprotein (HDL, or “good” cholesterol), hypertension, diabetes mellitus, obesity, lack of physical exercise, chronic kidney disease, excessive alcohol consumption, and use of illegal drugs. Coronary Veins Coronary veins drain the heart and generally parallel the large surface arteries (see Figure 19.15 ). The great cardiac vein can be seen initially on the surface of the heart following the interventricular sulcus, but it eventually flows along the coronary sulcus into the coronary sinus on the posterior surface. The great cardiac vein initially parallels the anterior interventricular artery and drains the areas supplied by this vessel. It receives several major branches, including the posterior cardiac vein, the middle cardiac vein, and the small cardiac vein. The posterior cardiac vein parallels and drains the areas supplied by the marginal artery branch of the circumflex artery. The middle cardiac vein parallels and drains the areas supplied by the posterior interventricular artery. The small cardiac vein parallels the right coronary artery and drains the blood from the posterior surfaces of the right atrium and ventricle. The coronary sinus is a large, thin-walled vein on the posterior surface of the heart lying within the atrioventricular sulcus and emptying directly into the right atrium. The anterior cardiac veins parallel the small cardiac arteries and drain the anterior surface of the right ventricle. Unlike these other cardiac veins, it bypasses the coronary sinus and drains directly into the right atrium. Disorders of the... Heart: Coronary Artery Disease Coronary artery disease is the leading cause of death worldwide. It occurs when the buildup of plaque—a fatty material including cholesterol, connective tissue, white blood cells, and some smooth muscle cells—within the walls of the arteries obstructs the flow of blood and decreases the flexibility or compliance of the vessels. This condition is called atherosclerosis, a hardening of the arteries that involves the accumulation of plaque. As the coronary blood vessels become occluded, the flow of blood to the tissues will be restricted, a condition called ischemia that causes the cells to receive insufficient amounts of oxygen, called hypoxia. Figure 19.16 shows the blockage of coronary arteries highlighted by the injection of dye. Some individuals with coronary artery disease report pain radiating from the chest called angina pectoris, but others remain asymptomatic. If untreated, coronary artery disease can lead to MI or a heart attack. The disease progresses slowly and often begins in children and can be seen as fatty “streaks” in the vessels. It then gradually progresses throughout life. Well-documented risk factors include smoking, family history, hypertension, obesity, diabetes, high alcohol consumption, lack of exercise, stress, and hyperlipidemia or high circulating levels of lipids in the blood. Treatments may include medication, changes to diet and exercise, angioplasty with a balloon catheter, insertion of a stent, or coronary bypass procedure. Angioplasty is a procedure in which the occlusion is mechanically widened with a balloon. A specialized catheter with an expandable tip is inserted into a superficial vessel, normally in the leg, and then directed to the site of the occlusion. At this point, the balloon is inflated to compress the plaque material and to open the vessel to increase blood flow. Then, the balloon is deflated and retracted. A stent consisting of a specialized mesh is typically inserted at the site of occlusion to reinforce the weakened and damaged walls. Stent insertions have been routine in cardiology for more than 40 years. Coronary bypass surgery may also be performed. This surgical procedure grafts a replacement vessel obtained from another, less vital portion of the body to bypass the occluded area. This procedure is clearly effective in treating patients experiencing a MI, but overall does not increase longevity. Nor does it seem advisable in patients with stable although diminished cardiac capacity since frequently loss of mental acuity occurs following the procedure. Long-term changes to behavior, emphasizing diet and exercise plus a medicine regime tailored to lower blood pressure, lower cholesterol and lipids, and reduce clotting are equally as effective. 19.2 Cardiac Muscle and Electrical Activity Learning Objectives By the end of this section, you will be able to: Describe the structure of cardiac muscle Identify and describe the components of the conducting system that distributes electrical impulses through the heart Compare the effect of ion movement on membrane potential of cardiac conductive and contractile cells Relate characteristics of an electrocardiogram to events in the cardiac cycle Identify blocks that can interrupt the cardiac cycle Recall that cardiac muscle shares a few characteristics with both skeletal muscle and smooth muscle, but it has some unique properties of its own. Not the least of these exceptional properties is its ability to initiate an electrical potential at a fixed rate that spreads rapidly from cell to cell to trigger the contractile mechanism. This property is known as autorhythmicity . Neither smooth nor skeletal muscle can do this. Even though cardiac muscle has autorhythmicity, heart rate is modulated by the endocrine and nervous systems. There are two major types of cardiac muscle cells: myocardial contractile cells and myocardial conducting cells. The myocardial contractile cells constitute the bulk (99 percent) of the cells in the atria and ventricles. Contractile cells conduct impulses and are responsible for contractions that pump blood through the body. The myocardial conducting cells (1 percent of the cells) form the conduction system of the heart. Except for Purkinje cells, they are generally much smaller than the contractile cells and have few of the myofibrils or filaments needed for contraction. Their function is similar in many respects to neurons, although they are specialized muscle cells. Myocardial conduction cells initiate and propagate the action potential (the electrical impulse) that travels throughout the heart and triggers the contractions that propel the blood. Structure of Cardiac Muscle Compared to the giant cylinders of skeletal muscle, cardiac muscle cells, or cardiomyocytes, are considerably shorter with much smaller diameters. Cardiac muscle also demonstrates striations, the alternating pattern of dark A bands and light I bands attributed to the precise arrangement of the myofilaments and fibrils that are organized in sarcomeres along the length of the cell ( Figure 19.17 a ). These contractile elements are virtually identical to skeletal muscle. T (transverse) tubules penetrate from the surface plasma membrane, the sarcolemma, to the interior of the cell, allowing the electrical impulse to reach the interior. The T tubules are only found at the Z discs, whereas in skeletal muscle, they are found at the junction of the A and I bands. Therefore, there are one-half as many T tubules in cardiac muscle as in skeletal muscle. In addition, the sarcoplasmic reticulum stores few calcium ions, so most of the calcium ions must come from outside the cells. The result is a slower onset of contraction. Mitochondria are plentiful, providing energy for the contractions of the heart. Typically, cardiomyocytes have a single, central nucleus, but two or more nuclei may be found in some cells. Cardiac muscle cells branch freely. A junction between two adjoining cells is marked by a critical structure called an intercalated disc , which helps support the synchronized contraction of the muscle ( Figure 19.17 b ). The sarcolemmas from adjacent cells bind together at the intercalated discs. They consist of desmosomes, specialized linking proteoglycans, tight junctions, and large numbers of gap junctions that allow the passage of ions between the cells and help to synchronize the contraction ( Figure 19.17 c ). Intercellular connective tissue also helps to bind the cells together. The importance of strongly binding these cells together is necessitated by the forces exerted by contraction. Cardiac muscle undergoes aerobic respiration patterns, primarily metabolizing lipids and carbohydrates. Myoglobin, lipids, and glycogen are all stored within the cytoplasm. Cardiac muscle cells undergo twitch-type contractions with long refractory periods followed by brief relaxation periods. The relaxation is essential so the heart can fill with blood for the next cycle. The refractory period is very long to prevent the possibility of tetany, a condition in which muscle remains involuntarily contracted. In the heart, tetany is not compatible with life, since it would prevent the heart from pumping blood. Everyday Connection Repair and Replacement Damaged cardiac muscle cells have extremely limited abilities to repair themselves or to replace dead cells via mitosis. Recent evidence indicates that at least some stem cells remain within the heart that continue to divide and at least potentially replace these dead cells. However, newly formed or repaired cells are rarely as functional as the original cells, and cardiac function is reduced. In the event of a heart attack or MI, dead cells are often replaced by patches of scar tissue. Autopsies performed on individuals who had successfully received heart transplants show some proliferation of original cells. If researchers can unlock the mechanism that generates new cells and restore full mitotic capabilities to heart muscle, the prognosis for heart attack survivors will be greatly enhanced. To date, myocardial cells produced within the patient ( in situ ) by cardiac stem cells seem to be nonfunctional, although those grown in Petri dishes ( in vitro ) do beat. Perhaps soon this mystery will be solved, and new advances in treatment will be commonplace. Conduction System of the Heart If embryonic heart cells are separated into a Petri dish and kept alive, each is capable of generating its own electrical impulse followed by contraction. When two independently beating embryonic cardiac muscle cells are placed together, the cell with the higher inherent rate sets the pace, and the impulse spreads from the faster to the slower cell to trigger a contraction. As more cells are joined together, the fastest cell continues to assume control of the rate. A fully developed adult heart maintains the capability of generating its own electrical impulse, triggered by the fastest cells, as part of the cardiac conduction system. The components of the cardiac conduction system include the sinoatrial node, the atrioventricular node, the atrioventricular bundle, the atrioventricular bundle branches, and the Purkinje cells ( Figure 19.18 ). Sinoatrial (SA) Node Normal cardiac rhythm is established by the sinoatrial (SA) node , a specialized clump of myocardial conducting cells located in the superior and posterior walls of the right atrium in close proximity to the orifice of the superior vena cava. The SA node has the highest inherent rate of depolarization and is known as the pacemaker of the heart. It initiates the sinus rhythm , or normal electrical pattern followed by contraction of the heart. This impulse spreads from its initiation in the SA node throughout the atria through specialized internodal pathways , to the atrial myocardial contractile cells and the atrioventricular node. The internodal pathways consist of three bands (anterior, middle, and posterior) that lead directly from the SA node to the next node in the conduction system, the atrioventricular node (see Figure 19.18 ). The impulse takes approximately 50 ms (milliseconds) to travel between these two nodes. The relative importance of this pathway has been debated since the impulse would reach the atrioventricular node simply following the cell-by-cell pathway through the contractile cells of the myocardium in the atria. In addition, there is a specialized pathway called Bachmann’s bundle or the interatrial band that conducts the impulse directly from the right atrium to the left atrium. Regardless of the pathway, as the impulse reaches the atrioventricular septum, the connective tissue of the cardiac skeleton prevents the impulse from spreading into the myocardial cells in the ventricles except at the atrioventricular node. Figure 19.19 illustrates the initiation of the impulse in the SA node that then spreads the impulse throughout the atria to the atrioventricular node. The electrical event, the wave of depolarization, is the trigger for muscular contraction. The wave of depolarization begins in the right atrium, and the impulse spreads across the superior portions of both atria and then down through the contractile cells. The contractile cells then begin contraction from the superior to the inferior portions of the atria, efficiently pumping blood into the ventricles. Atrioventricular (AV) Node The atrioventricular (AV) node is a second clump of specialized myocardial conductive cells, located in the inferior portion of the right atrium within the atrioventricular septum. The septum prevents the impulse from spreading directly to the ventricles without passing through the AV node. There is a critical pause before the AV node depolarizes and transmits the impulse to the atrioventricular bundle (see Figure 19.19 , step 3). This delay in transmission is partially attributable to the small diameter of the cells of the node, which slow the impulse. Also, conduction between nodal cells is less efficient than between conducting cells. These factors mean that it takes the impulse approximately 100 ms to pass through the node. This pause is critical to heart function, as it allows the atrial cardiomyocytes to complete their contraction that pumps blood into the ventricles before the impulse is transmitted to the cells of the ventricle itself. With extreme stimulation by the SA node, the AV node can transmit impulses maximally at 220 per minute. This establishes the typical maximum heart rate in a healthy young individual. Damaged hearts or those stimulated by drugs can contract at higher rates, but at these rates, the heart can no longer effectively pump blood. Atrioventricular Bundle (Bundle of His), Bundle Branches, and Purkinje Fibers Arising from the AV node, the atrioventricular bundle , or bundle of His , proceeds through the interventricular septum before dividing into two atrioventricular bundle branches , commonly called the left and right bundle branches. The left bundle branch has two fascicles. The left bundle branch supplies the left ventricle, and the right bundle branch the right ventricle. Since the left ventricle is much larger than the right, the left bundle branch is also considerably larger than the right. Portions of the right bundle branch are found in the moderator band and supply the right papillary muscles. Because of this connection, each papillary muscle receives the impulse at approximately the same time, so they begin to contract simultaneously just prior to the remainder of the myocardial contractile cells of the ventricles. This is believed to allow tension to develop on the chordae tendineae prior to right ventricular contraction. There is no corresponding moderator band on the left. Both bundle branches descend and reach the apex of the heart where they connect with the Purkinje fibers (see Figure 19.19 , step 4). This passage takes approximately 25 ms. The Purkinje fibers are additional myocardial conductive fibers that spread the impulse to the myocardial contractile cells in the ventricles. They extend throughout the myocardium from the apex of the heart toward the atrioventricular septum and the base of the heart. The Purkinje fibers have a fast inherent conduction rate, and the electrical impulse reaches all of the ventricular muscle cells in about 75 ms (see Figure 19.19 , step 5). Since the electrical stimulus begins at the apex, the contraction also begins at the apex and travels toward the base of the heart, similar to squeezing a tube of toothpaste from the bottom. This allows the blood to be pumped out of the ventricles and into the aorta and pulmonary trunk. The total time elapsed from the initiation of the impulse in the SA node until depolarization of the ventricles is approximately 225 ms. Membrane Potentials and Ion Movement in Cardiac Conductive Cells Action potentials are considerably different between cardiac conductive cells and cardiac contractive cells. While Na + and K + play essential roles, Ca 2+ is also critical for both types of cells. Unlike skeletal muscles and neurons, cardiac conductive cells do not have a stable resting potential. Conductive cells contain a series of sodium ion channels that allow a normal and slow influx of sodium ions that causes the membrane potential to rise slowly from an initial value of −60 mV up to about –40 mV. The resulting movement of sodium ions creates spontaneous depolarization (or prepotential depolarization ). At this point, calcium ion channels open and Ca 2+ enters the cell, further depolarizing it at a more rapid rate until it reaches a value of approximately +15 mV. At this point, the calcium ion channels close and K + channels open, allowing outflux of K + and resulting in repolarization. When the membrane potential reaches approximately −60 mV, the K + channels close and Na + channels open, and the prepotential phase begins again. This phenomenon explains the autorhythmicity properties of cardiac muscle ( Figure 19.20 ). Membrane Potentials and Ion Movement in Cardiac Contractile Cells There is a distinctly different electrical pattern involving the contractile cells. In this case, there is a rapid depolarization, followed by a plateau phase and then repolarization. This phenomenon accounts for the long refractory periods required for the cardiac muscle cells to pump blood effectively before they are capable of firing for a second time. These cardiac myocytes normally do not initiate their own electrical potential but rather wait for an impulse to reach them. Contractile cells demonstrate a much more stable resting phase than conductive cells at approximately −80 mV for cells in the atria and −90 mV for cells in the ventricles. Despite this initial difference, the other components of their action potentials are virtually identical. In both cases, when stimulated by an action potential, voltage-gated channels rapidly open, beginning the positive-feedback mechanism of depolarization. This rapid influx of positively charged ions raises the membrane potential to approximately +30 mV, at which point the sodium channels close. The rapid depolarization period typically lasts 3–5 ms. Depolarization is followed by the plateau phase, in which membrane potential declines relatively slowly. This is due in large part to the opening of the slow Ca 2+ channels, allowing Ca 2+ to enter the cell while few K + channels are open, allowing K + to exit the cell. The relatively long plateau phase lasts approximately 175 ms. Once the membrane potential reaches approximately zero, the Ca 2+ channels close and K + channels open, allowing K + to exit the cell. The repolarization lasts approximately 75 ms. At this point, membrane potential drops until it reaches resting levels once more and the cycle repeats. The entire event lasts between 250 and 300 ms ( Figure 19.21 ). The absolute refractory period for cardiac contractile muscle lasts approximately 200 ms, and the relative refractory period lasts approximately 50 ms, for a total of 250 ms. This extended period is critical, since the heart muscle must contract to pump blood effectively and the contraction must follow the electrical events. Without extended refractory periods, premature contractions would occur in the heart and would not be compatible with life. Calcium Ions Calcium ions play two critical roles in the physiology of cardiac muscle. Their influx through slow calcium channels accounts for the prolonged plateau phase and absolute refractory period that enable cardiac muscle to function properly. Calcium ions also combine with the regulatory protein troponin in the troponin-tropomyosin complex; this complex removes the inhibition that prevents the heads of the myosin molecules from forming cross bridges with the active sites on actin that provide the power stroke of contraction. This mechanism is virtually identical to that of skeletal muscle. Approximately 20 percent of the calcium required for contraction is supplied by the influx of Ca 2+ during the plateau phase. The remaining Ca 2+ for contraction is released from storage in the sarcoplasmic reticulum. Comparative Rates of Conduction System Firing The pattern of prepotential or spontaneous depolarization, followed by rapid depolarization and repolarization just described, are seen in the SA node and a few other conductive cells in the heart. Since the SA node is the pacemaker, it reaches threshold faster than any other component of the conduction system. It will initiate the impulses spreading to the other conducting cells. The SA node, without nervous or endocrine control, would initiate a heart impulse approximately 80–100 times per minute. Although each component of the conduction system is capable of generating its own impulse, the rate progressively slows as you proceed from the SA node to the Purkinje fibers. Without the SA node, the AV node would generate a heart rate of 40–60 beats per minute. If the AV node were blocked, the atrioventricular bundle would fire at a rate of approximately 30–40 impulses per minute. The bundle branches would have an inherent rate of 20–30 impulses per minute, and the Purkinje fibers would fire at 15–20 impulses per minute. While a few exceptionally trained aerobic athletes demonstrate resting heart rates in the range of 30–40 beats per minute (the lowest recorded figure is 28 beats per minute for Miguel Indurain, a cyclist), for most individuals, rates lower than 50 beats per minute would indicate a condition called bradycardia. Depending upon the specific individual, as rates fall much below this level, the heart would be unable to maintain adequate flow of blood to vital tissues, initially resulting in decreasing loss of function across the systems, unconsciousness, and ultimately death. Electrocardiogram By careful placement of surface electrodes on the body, it is possible to record the complex, compound electrical signal of the heart. This tracing of the electrical signal is the electrocardiogram (ECG) , also commonly abbreviated EKG (K coming kardiology, from the German term for cardiology). Careful analysis of the ECG reveals a detailed picture of both normal and abnormal heart function, and is an indispensable clinical diagnostic tool. The standard electrocardiograph (the instrument that generates an ECG) uses 3, 5, or 12 leads. The greater the number of leads an electrocardiograph uses, the more information the ECG provides. The term “lead” may be used to refer to the cable from the electrode to the electrical recorder, but it typically describes the voltage difference between two of the electrodes. The 12-lead electrocardiograph uses 10 electrodes placed in standard locations on the patient’s skin ( Figure 19.22 ). In continuous ambulatory electrocardiographs, the patient wears a small, portable, battery-operated device known as a Holter monitor, or simply a Holter, that continuously monitors heart electrical activity, typically for a period of 24 hours during the patient’s normal routine. A normal ECG tracing is presented in Figure 19.23 . Each component, segment, and interval is labeled and corresponds to important electrical events, demonstrating the relationship between these events and contraction in the heart. There are five prominent points on the ECG: the P wave, the QRS complex, and the T wave. The small P wave represents the depolarization of the atria. The atria begin contracting approximately 25 ms after the start of the P wave. The large QRS complex represents the depolarization of the ventricles, which requires a much stronger electrical signal because of the larger size of the ventricular cardiac muscle. The ventricles begin to contract as the QRS reaches the peak of the R wave. Lastly, the T wave represents the repolarization of the ventricles. The repolarization of the atria occurs during the QRS complex, which masks it on an ECG. The major segments and intervals of an ECG tracing are indicated in Figure 19.23 . Segments are defined as the regions between two waves. Intervals include one segment plus one or more waves. For example, the PR segment begins at the end of the P wave and ends at the beginning of the QRS complex. The PR interval starts at the beginning of the P wave and ends with the beginning of the QRS complex. The PR interval is more clinically relevant, as it measures the duration from the beginning of atrial depolarization (the P wave) to the initiation of the QRS complex. Since the Q wave may be difficult to view in some tracings, the measurement is often extended to the R that is more easily visible. Should there be a delay in passage of the impulse from the SA node to the AV node, it would be visible in the PR interval. Figure 19.24 correlates events of heart contraction to the corresponding segments and intervals of an ECG. Interactive Link Visit this site for a more detailed analysis of ECGs. Everyday Connection ECG Abnormalities Occassionally, an area of the heart other than the SA node will initiate an impulse that will be followed by a premature contraction. Such an area, which may actually be a component of the conduction system or some other contractile cells, is known as an ectopic focus or ectopic pacemaker. An ectopic focus may be stimulated by localized ischemia; exposure to certain drugs, including caffeine, digitalis, or acetylcholine; elevated stimulation by both sympathetic or parasympathetic divisions of the autonomic nervous system; or a number of disease or pathological conditions. Occasional occurances are generally transitory and nonlife threatening, but if the condition becomes chronic, it may lead to either an arrhythmia, a deviation from the normal pattern of impulse conduction and contraction, or to fibrillation, an uncoordinated beating of the heart. While interpretation of an ECG is possible and extremely valuable after some training, a full understanding of the complexities and intricacies generally requires several years of experience. In general, the size of the electrical variations, the duration of the events, and detailed vector analysis provide the most comprehensive picture of cardiac function. For example, an amplified P wave may indicate enlargement of the atria, an enlarged Q wave may indicate a MI, and an enlarged suppressed or inverted Q wave often indicates enlarged ventricles. T waves often appear flatter when insufficient oxygen is being delivered to the myocardium. An elevation of the ST segment above baseline is often seen in patients with an acute MI, and may appear depressed below the baseline when hypoxia is occurring. As useful as analyzing these electrical recordings may be, there are limitations. For example, not all areas suffering a MI may be obvious on the ECG. Additionally, it will not reveal the effectiveness of the pumping, which requires further testing, such as an ultrasound test called an echocardiogram or nuclear medicine imaging. It is also possible for there to be pulseless electrical activity, which will show up on an ECG tracing, although there is no corresponding pumping action. Common abnormalities that may be detected by the ECGs are shown in Figure 19.25 . Interactive Link Visit this site for a more complete library of abnormal ECGs. Everyday Connection External Automated Defibrillators In the event that the electrical activity of the heart is severely disrupted, cessation of electrical activity or fibrillation may occur. In fibrillation, the heart beats in a wild, uncontrolled manner, which prevents it from being able to pump effectively. Atrial fibrillation (see Figure 19.25 b ) is a serious condition, but as long as the ventricles continue to pump blood, the patient’s life may not be in immediate danger. Ventricular fibrillation (see Figure 19.25 d ) is a medical emergency that requires life support, because the ventricles are not effectively pumping blood. In a hospital setting, it is often described as “code blue.” If untreated for as little as a few minutes, ventricular fibrillation may lead to brain death. The most common treatment is defibrillation, which uses special paddles to apply a charge to the heart from an external electrical source in an attempt to establish a normal sinus rhythm ( Figure 19.26 ). A defibrillator effectively stops the heart so that the SA node can trigger a normal conduction cycle. Because of their effectiveness in reestablishing a normal sinus rhythm, external automated defibrillators (EADs) are being placed in areas frequented by large numbers of people, such as schools, restaurants, and airports. These devices contain simple and direct verbal instructions that can be followed by nonmedical personnel in an attempt to save a life. A heart block refers to an interruption in the normal conduction pathway. The nomenclature for these is very straightforward. SA nodal blocks occur within the SA node. AV nodal blocks occur within the AV node. Infra-Hisian blocks involve the bundle of His. Bundle branch blocks occur within either the left or right atrioventricular bundle branches. Hemiblocks are partial and occur within one or more fascicles of the atrioventricular bundle branch. Clinically, the most common types are the AV nodal and infra-Hisian blocks. AV blocks are often described by degrees. A first-degree or partial block indicates a delay in conduction between the SA and AV nodes. This can be recognized on the ECG as an abnormally long PR interval. A second-degree or incomplete block occurs when some impulses from the SA node reach the AV node and continue, while others do not. In this instance, the ECG would reveal some P waves not followed by a QRS complex, while others would appear normal. In the third-degree or complete block, there is no correlation between atrial activity (the P wave) and ventricular activity (the QRS complex). Even in the event of a total SA block, the AV node will assume the role of pacemaker and continue initiating contractions at 40–60 contractions per minute, which is adequate to maintain consciousness. Second- and third-degree blocks are demonstrated on the ECG presented in Figure 19.25 . When arrhythmias become a chronic problem, the heart maintains a junctional rhythm, which originates in the AV node. In order to speed up the heart rate and restore full sinus rhythm, a cardiologist can implant an artificial pacemaker , which delivers electrical impulses to the heart muscle to ensure that the heart continues to contract and pump blood effectively. These artificial pacemakers are programmable by the cardiologists and can either provide stimulation temporarily upon demand or on a continuous basis. Some devices also contain built-in defibrillators. Cardiac Muscle Metabolism Normally, cardiac muscle metabolism is entirely aerobic. Oxygen from the lungs is brought to the heart, and every other organ, attached to the hemoglobin molecules within the erythrocytes. Heart cells also store appreciable amounts of oxygen in myoglobin. Normally, these two mechanisms, circulating oxygen and oxygen attached to myoglobin, can supply sufficient oxygen to the heart, even during peak performance. Fatty acids and glucose from the circulation are broken down within the mitochondria to release energy in the form of ATP. Both fatty acid droplets and glycogen are stored within the sarcoplasm and provide additional nutrient supply. (Seek additional content for more detail about metabolism.) 19.3 Cardiac Cycle Learning Objectives By the end of this section, you will be able to: Describe the relationship between blood pressure and blood flow Summarize the events of the cardiac cycle Compare atrial and ventricular systole and diastole Relate heart sounds detected by auscultation to action of heart’s valves The period of time that begins with contraction of the atria and ends with ventricular relaxation is known as the cardiac cycle ( Figure 19.27 ). The period of contraction that the heart undergoes while it pumps blood into circulation is called systole . The period of relaxation that occurs as the chambers fill with blood is called diastole . Both the atria and ventricles undergo systole and diastole, and it is essential that these components be carefully regulated and coordinated to ensure blood is pumped efficiently to the body. Pressures and Flow Fluids, whether gases or liquids, are materials that flow according to pressure gradients—that is, they move from regions that are higher in pressure to regions that are lower in pressure. Accordingly, when the heart chambers are relaxed (diastole), blood will flow into the atria from the veins, which are higher in pressure. As blood flows into the atria, the pressure will rise, so the blood will initially move passively from the atria into the ventricles. When the action potential triggers the muscles in the atria to contract (atrial systole), the pressure within the atria rises further, pumping blood into the ventricles. During ventricular systole, pressure rises in the ventricles, pumping blood into the pulmonary trunk from the right ventricle and into the aorta from the left ventricle. Again, as you consider this flow and relate it to the conduction pathway, the elegance of the system should become apparent. Phases of the Cardiac Cycle At the beginning of the cardiac cycle, both the atria and ventricles are relaxed (diastole). Blood is flowing into the right atrium from the superior and inferior venae cavae and the coronary sinus. Blood flows into the left atrium from the four pulmonary veins. The two atrioventricular valves, the tricuspid and mitral valves, are both open, so blood flows unimpeded from the atria and into the ventricles. Approximately 70–80 percent of ventricular filling occurs by this method. The two semilunar valves, the pulmonary and aortic valves, are closed, preventing backflow of blood into the right and left ventricles from the pulmonary trunk on the right and the aorta on the left. Atrial Systole and Diastole Contraction of the atria follows depolarization, represented by the P wave of the ECG. As the atrial muscles contract from the superior portion of the atria toward the atrioventricular septum, pressure rises within the atria and blood is pumped into the ventricles through the open atrioventricular (tricuspid, and mitral or bicuspid) valves. At the start of atrial systole, the ventricles are normally filled with approximately 70–80 percent of their capacity due to inflow during diastole. Atrial contraction, also referred to as the “atrial kick,” contributes the remaining 20–30 percent of filling (see Figure 19.27 ). Atrial systole lasts approximately 100 ms and ends prior to ventricular systole, as the atrial muscle returns to diastole. Ventricular Systole Ventricular systole (see Figure 19.27 ) follows the depolarization of the ventricles and is represented by the QRS complex in the ECG. It may be conveniently divided into two phases, lasting a total of 270 ms. At the end of atrial systole and just prior to ventricular contraction, the ventricles contain approximately 130 mL blood in a resting adult in a standing position. This volume is known as the end diastolic volume (EDV) or preload . Initially, as the muscles in the ventricle contract, the pressure of the blood within the chamber rises, but it is not yet high enough to open the semilunar (pulmonary and aortic) valves and be ejected from the heart. However, blood pressure quickly rises above that of the atria that are now relaxed and in diastole. This increase in pressure causes blood to flow back toward the atria, closing the tricuspid and mitral valves. Since blood is not being ejected from the ventricles at this early stage, the volume of blood within the chamber remains constant. Consequently, this initial phase of ventricular systole is known as isovolumic contraction , also called isovolumetric contraction (see Figure 19.27 ). In the second phase of ventricular systole, the ventricular ejection phase , the contraction of the ventricular muscle has raised the pressure within the ventricle to the point that it is greater than the pressures in the pulmonary trunk and the aorta. Blood is pumped from the heart, pushing open the pulmonary and aortic semilunar valves. Pressure generated by the left ventricle will be appreciably greater than the pressure generated by the right ventricle, since the existing pressure in the aorta will be so much higher. Nevertheless, both ventricles pump the same amount of blood. This quantity is referred to as stroke volume. Stroke volume will normally be in the range of 70–80 mL. Since ventricular systole began with an EDV of approximately 130 mL of blood, this means that there is still 50–60 mL of blood remaining in the ventricle following contraction. This volume of blood is known as the end systolic volume (ESV) . Ventricular Diastole Ventricular relaxation, or diastole, follows repolarization of the ventricles and is represented by the T wave of the ECG. It too is divided into two distinct phases and lasts approximately 430 ms. During the early phase of ventricular diastole, as the ventricular muscle relaxes, pressure on the remaining blood within the ventricle begins to fall. When pressure within the ventricles drops below pressure in both the pulmonary trunk and aorta, blood flows back toward the heart, producing the dicrotic notch (small dip) seen in blood pressure tracings. The semilunar valves close to prevent backflow into the heart. Since the atrioventricular valves remain closed at this point, there is no change in the volume of blood in the ventricle, so the early phase of ventricular diastole is called the isovolumic ventricular relaxation phase , also called isovolumetric ventricular relaxation phase (see Figure 19.27 ). In the second phase of ventricular diastole, called late ventricular diastole, as the ventricular muscle relaxes, pressure on the blood within the ventricles drops even further. Eventually, it drops below the pressure in the atria. When this occurs, blood flows from the atria into the ventricles, pushing open the tricuspid and mitral valves. As pressure drops within the ventricles, blood flows from the major veins into the relaxed atria and from there into the ventricles. Both chambers are in diastole, the atrioventricular valves are open, and the semilunar valves remain closed (see Figure 19.27 ). The cardiac cycle is complete. Figure 19.28 illustrates the relationship between the cardiac cycle and the ECG. Heart Sounds One of the simplest, yet effective, diagnostic techniques applied to assess the state of a patient’s heart is auscultation using a stethoscope. In a normal, healthy heart, there are only two audible heart sounds : S 1 and S 2 . S 1 is the sound created by the closing of the atrioventricular valves during ventricular contraction and is normally described as a “lub,” or first heart sound. The second heart sound, S 2 , is the sound of the closing of the semilunar valves during ventricular diastole and is described as a “dub” ( Figure 19.29 ). In both cases, as the valves close, the openings within the atrioventricular septum guarded by the valves will become reduced, and blood flow through the opening will become more turbulent until the valves are fully closed. There is a third heart sound, S 3 , but it is rarely heard in healthy individuals. It may be the sound of blood flowing into the atria, or blood sloshing back and forth in the ventricle, or even tensing of the chordae tendineae. S 3 may be heard in youth, some athletes, and pregnant women. If the sound is heard later in life, it may indicate congestive heart failure, warranting further tests. Some cardiologists refer to the collective S 1 , S 2 , and S 3 sounds as the “Kentucky gallop,” because they mimic those produced by a galloping horse. The fourth heart sound, S 4 , results from the contraction of the atria pushing blood into a stiff or hypertrophic ventricle, indicating failure of the left ventricle. S 4 occurs prior to S 1 and the collective sounds S 4 , S 1 , and S 2 are referred to by some cardiologists as the “Tennessee gallop,” because of their similarity to the sound produced by a galloping horse with a different gait. A few individuals may have both S 3 and S 4 , and this combined sound is referred to as S 7 . The term murmur is used to describe an unusual sound coming from the heart that is caused by the turbulent flow of blood. Murmurs are graded on a scale of 1 to 6, with 1 being the most common, the most difficult sound to detect, and the least serious. The most severe is a 6. Phonocardiograms or auscultograms can be used to record both normal and abnormal sounds using specialized electronic stethoscopes. During auscultation, it is common practice for the clinician to ask the patient to breathe deeply. This procedure not only allows for listening to airflow, but it may also amplify heart murmurs. Inhalation increases blood flow into the right side of the heart and may increase the amplitude of right-sided heart murmurs. Expiration partially restricts blood flow into the left side of the heart and may amplify left-sided heart murmurs. Figure 19.30 indicates proper placement of the bell of the stethoscope to facilitate auscultation. 19.4 Cardiac Physiology Learning Objectives By the end of this section, you will be able to: Relate heart rate to cardiac output Describe the effect of exercise on heart rate Identify cardiovascular centers and cardiac reflexes that regulate heart function Describe factors affecting heart rate Distinguish between positive and negative factors that affect heart contractility Summarize factors affecting stroke volume and cardiac output Describe the cardiac response to variations in blood flow and pressure The autorhythmicity inherent in cardiac cells keeps the heart beating at a regular pace; however, the heart is regulated by and responds to outside influences as well. Neural and endocrine controls are vital to the regulation of cardiac function. In addition, the heart is sensitive to several environmental factors, including electrolytes. Resting Cardiac Output Cardiac output (CO) is a measurement of the amount of blood pumped by each ventricle in one minute. To calculate this value, multiply stroke volume (SV) , the amount of blood pumped by each ventricle, by heart rate (HR) , in contractions per minute (or beats per minute, bpm). It can be represented mathematically by the following equation: CO = HR × SV SV is normally measured using an echocardiogram to record EDV and ESV, and calculating the difference: SV = EDV – ESV. SV can also be measured using a specialized catheter, but this is an invasive procedure and far more dangerous to the patient. A mean SV for a resting 70-kg (150-lb) individual would be approximately 70 mL. There are several important variables, including size of the heart, physical and mental condition of the individual, sex, contractility, duration of contraction, preload or EDV, and afterload or resistance. Normal range for SV would be 55–100 mL. An average resting HR would be approximately 75 bpm but could range from 60–100 in some individuals. Using these numbers, the mean CO is 5.25 L/min, with a range of 4.0–8.0 L/min. Remember, however, that these numbers refer to CO from each ventricle separately, not the total for the heart. Factors influencing CO are summarized in Figure 19.31 . SVs are also used to calculate ejection fraction , which is the portion of the blood that is pumped or ejected from the heart with each contraction. To calculate ejection fraction, SV is divided by EDV. Despite the name, the ejection fraction is normally expressed as a percentage. Ejection fractions range from approximately 55–70 percent, with a mean of 58 percent. Exercise and Maximum Cardiac Output In healthy young individuals, HR may increase to 150 bpm during exercise. SV can also increase from 70 to approximately 130 mL due to increased strength of contraction. This would increase CO to approximately 19.5 L/min, 4–5 times the resting rate. Top cardiovascular athletes can achieve even higher levels. At their peak performance, they may increase resting CO by 7–8 times. Since the heart is a muscle, exercising it increases its efficiency. The difference between maximum and resting CO is known as the cardiac reserve . It measures the residual capacity of the heart to pump blood. Heart Rates HRs vary considerably, not only with exercise and fitness levels, but also with age. Newborn resting HRs may be 120 bpm. HR gradually decreases until young adulthood and then gradually increases again with age. Maximum HRs are normally in the range of 200–220 bpm, although there are some extreme cases in which they may reach higher levels. As one ages, the ability to generate maximum rates decreases. This may be estimated by taking the maximal value of 220 bpm and subtracting the individual’s age. So a 40-year-old individual would be expected to hit a maximum rate of approximately 180, and a 60-year-old person would achieve a HR of 160. Disorders of the... Heart: Abnormal Heart Rates For an adult, normal resting HR will be in the range of 60–100 bpm. Bradycardia is the condition in which resting rate drops below 60 bpm, and tachycardia is the condition in which the resting rate is above 100 bpm. Trained athletes typically have very low HRs. If the patient is not exhibiting other symptoms, such as weakness, fatigue, dizziness, fainting, chest discomfort, palpitations, or respiratory distress, bradycardia is not considered clinically significant. However, if any of these symptoms are present, they may indicate that the heart is not providing sufficient oxygenated blood to the tissues. The term relative bradycardia may be used with a patient who has a HR in the normal range but is still suffering from these symptoms. Most patients remain asymptomatic as long as the HR remains above 50 bpm. Bradycardia may be caused by either inherent factors or causes external to the heart. While the condition may be inherited, typically it is acquired in older individuals. Inherent causes include abnormalities in either the SA or AV node. If the condition is serious, a pacemaker may be required. Other causes include ischemia to the heart muscle or diseases of the heart vessels or valves. External causes include metabolic disorders, pathologies of the endocrine system often involving the thyroid, electrolyte imbalances, neurological disorders including inappropriate autonomic responses, autoimmune pathologies, over-prescription of beta blocker drugs that reduce HR, recreational drug use, or even prolonged bed rest. Treatment relies upon establishing the underlying cause of the disorder and may necessitate supplemental oxygen. Tachycardia is not normal in a resting patient but may be detected in pregnant women or individuals experiencing extreme stress. In the latter case, it would likely be triggered by stimulation from the limbic system or disorders of the autonomic nervous system. In some cases, tachycardia may involve only the atria. Some individuals may remain asymptomatic, but when present, symptoms may include dizziness, shortness of breath, lightheadedness, rapid pulse, heart palpations, chest pain, or fainting (syncope). While tachycardia is defined as a HR above 100 bpm, there is considerable variation among people. Further, the normal resting HRs of children are often above 100 bpm, but this is not considered to be tachycardia Many causes of tachycardia may be benign, but the condition may also be correlated with fever, anemia, hypoxia, hyperthyroidism, hypersecretion of catecholamines, some cardiomyopathies, some disorders of the valves, and acute exposure to radiation. Elevated rates in an exercising or resting patient are normal and expected. Resting rate should always be taken after recovery from exercise. Treatment depends upon the underlying cause but may include medications, implantable cardioverter defibrillators, ablation, or surgery. Correlation Between Heart Rates and Cardiac Output Initially, physiological conditions that cause HR to increase also trigger an increase in SV. During exercise, the rate of blood returning to the heart increases. However as the HR rises, there is less time spent in diastole and consequently less time for the ventricles to fill with blood. Even though there is less filling time, SV will initially remain high. However, as HR continues to increase, SV gradually decreases due to decreased filling time. CO will initially stabilize as the increasing HR compensates for the decreasing SV, but at very high rates, CO will eventually decrease as increasing rates are no longer able to compensate for the decreasing SV. Consider this phenomenon in a healthy young individual. Initially, as HR increases from resting to approximately 120 bpm, CO will rise. As HR increases from 120 to 160 bpm, CO remains stable, since the increase in rate is offset by decreasing ventricular filling time and, consequently, SV. As HR continues to rise above 160 bpm, CO actually decreases as SV falls faster than HR increases. So although aerobic exercises are critical to maintain the health of the heart, individuals are cautioned to monitor their HR to ensure they stay within the target heart rate range of between 120 and 160 bpm, so CO is maintained. The target HR is loosely defined as the range in which both the heart and lungs receive the maximum benefit from the aerobic workout and is dependent upon age. Cardiovascular Centers Nervous control over HR is centralized within the two paired cardiovascular centers of the medulla oblongata ( Figure 19.32 ). The cardioaccelerator regions stimulate activity via sympathetic stimulation of the cardioaccelerator nerves, and the cardioinhibitory centers decrease heart activity via parasympathetic stimulation as one component of the vagus nerve, cranial nerve X. During rest, both centers provide slight stimulation to the heart, contributing to autonomic tone . This is a similar concept to tone in skeletal muscles. Normally, vagal stimulation predominates as, left unregulated, the SA node would initiate a sinus rhythm of approximately 100 bpm. Both sympathetic and parasympathetic stimulations flow through a paired complex network of nerve fibers known as the cardiac plexus near the base of the heart. The cardioaccelerator center also sends additional fibers, forming the cardiac nerves via sympathetic ganglia (the cervical ganglia plus superior thoracic ganglia T1–T4) to both the SA and AV nodes, plus additional fibers to the atria and ventricles. The ventricles are more richly innervated by sympathetic fibers than parasympathetic fibers. Sympathetic stimulation causes the release of the neurotransmitter norepinephrine (NE) at the neuromuscular junction of the cardiac nerves. NE shortens the repolarization period, thus speeding the rate of depolarization and contraction, which results in an increase in HR. It opens chemical- or ligand-gated sodium and calcium ion channels, allowing an influx of positively charged ions. NE binds to the beta-1 receptor. Some cardiac medications (for example, beta blockers) work by blocking these receptors, thereby slowing HR and are one possible treatment for hypertension. Overprescription of these drugs may lead to bradycardia and even stoppage of the heart. Parasympathetic stimulation originates from the cardioinhibitory region with impulses traveling via the vagus nerve (cranial nerve X). The vagus nerve sends branches to both the SA and AV nodes, and to portions of both the atria and ventricles. Parasympathetic stimulation releases the neurotransmitter acetylcholine (ACh) at the neuromuscular junction. ACh slows HR by opening chemical- or ligand-gated potassium ion channels to slow the rate of spontaneous depolarization, which extends repolarization and increases the time before the next spontaneous depolarization occurs. Without any nervous stimulation, the SA node would establish a sinus rhythm of approximately 100 bpm. Since resting rates are considerably less than this, it becomes evident that parasympathetic stimulation normally slows HR. This is similar to an individual driving a car with one foot on the brake pedal. To speed up, one need merely remove one’s foot from the break and let the engine increase speed. In the case of the heart, decreasing parasympathetic stimulation decreases the release of ACh, which allows HR to increase up to approximately 100 bpm. Any increases beyond this rate would require sympathetic stimulation. Figure 19.33 illustrates the effects of parasympathetic and sympathetic stimulation on the normal sinus rhythm. Input to the Cardiovascular Center The cardiovascular center receives input from a series of visceral receptors with impulses traveling through visceral sensory fibers within the vagus and sympathetic nerves via the cardiac plexus. Among these receptors are various proprioreceptors, baroreceptors, and chemoreceptors, plus stimuli from the limbic system. Collectively, these inputs normally enable the cardiovascular centers to regulate heart function precisely, a process known as cardiac reflexes . Increased physical activity results in increased rates of firing by various proprioreceptors located in muscles, joint capsules, and tendons. Any such increase in physical activity would logically warrant increased blood flow. The cardiac centers monitor these increased rates of firing, and suppress parasympathetic stimulation and increase sympathetic stimulation as needed in order to increase blood flow. Similarly, baroreceptors are stretch receptors located in the aortic sinus, carotid bodies, the venae cavae, and other locations, including pulmonary vessels and the right side of the heart itself. Rates of firing from the baroreceptors represent blood pressure, level of physical activity, and the relative distribution of blood. The cardiac centers monitor baroreceptor firing to maintain cardiac homeostasis, a mechanism called the baroreceptor reflex . With increased pressure and stretch, the rate of baroreceptor firing increases, and the cardiac centers decrease sympathetic stimulation and increase parasympathetic stimulation. As pressure and stretch decrease, the rate of baroreceptor firing decreases, and the cardiac centers increase sympathetic stimulation and decrease parasympathetic stimulation. There is a similar reflex, called the atrial reflex or Bainbridge reflex , associated with varying rates of blood flow to the atria. Increased venous return stretches the walls of the atria where specialized baroreceptors are located. However, as the atrial baroreceptors increase their rate of firing and as they stretch due to the increased blood pressure, the cardiac center responds by increasing sympathetic stimulation and inhibiting parasympathetic stimulation to increase HR. The opposite is also true. Increased metabolic byproducts associated with increased activity, such as carbon dioxide, hydrogen ions, and lactic acid, plus falling oxygen levels, are detected by a suite of chemoreceptors innervated by the glossopharyngeal and vagus nerves. These chemoreceptors provide feedback to the cardiovascular centers about the need for increased or decreased blood flow, based on the relative levels of these substances. The limbic system can also significantly impact HR related to emotional state. During periods of stress, it is not unusual to identify higher than normal HRs, often accompanied by a surge in the stress hormone cortisol. Individuals experiencing extreme anxiety may manifest panic attacks with symptoms that resemble those of heart attacks. These events are typically transient and treatable. Meditation techniques have been developed to ease anxiety and have been shown to lower HR effectively. Doing simple deep and slow breathing exercises with one’s eyes closed can also significantly reduce this anxiety and HR. Disorders of the... Heart: Broken Heart Syndrome Extreme stress from such life events as the death of a loved one, an emotional break up, loss of income, or foreclosure of a home may lead to a condition commonly referred to as broken heart syndrome. This condition may also be called Takotsubo cardiomyopathy, transient apical ballooning syndrome, apical ballooning cardiomyopathy, stress-induced cardiomyopathy, Gebrochenes-Herz syndrome, and stress cardiomyopathy. The recognized effects on the heart include congestive heart failure due to a profound weakening of the myocardium not related to lack of oxygen. This may lead to acute heart failure, lethal arrhythmias, or even the rupture of a ventricle. The exact etiology is not known, but several factors have been suggested, including transient vasospasm, dysfunction of the cardiac capillaries, or thickening of the myocardium—particularly in the left ventricle—that may lead to the critical circulation of blood to this region. While many patients survive the initial acute event with treatment to restore normal function, there is a strong correlation with death. Careful statistical analysis by the Cass Business School, a prestigious institution located in London, published in 2008, revealed that within one year of the death of a loved one, women are more than twice as likely to die and males are six times as likely to die as would otherwise be expected. Other Factors Influencing Heart Rate Using a combination of autorhythmicity and innervation, the cardiovascular center is able to provide relatively precise control over HR. However, there are a number of other factors that have an impact on HR as well, including epinephrine, NE, and thyroid hormones; levels of various ions including calcium, potassium, and sodium; body temperature; hypoxia; and pH balance ( Table 19.1 and Table 19.2 ). After reading this section, the importance of maintaining homeostasis should become even more apparent. Major Factors Increasing Heart Rate and Force of Contraction Factor Effect Cardioaccelerator nerves Release of norepinephrine by cardioinhibitory nerves Proprioreceptors Increased firing rates of proprioreceptors (e.g. during exercise) Chemoreceptors Chemoreceptors sensing decreased levels of O 2 or increased levels of H + , CO 2 and lactic acid Baroreceptors Decreased firing rates of baroreceptors (indicating falling blood volume/pressure) Limbic system Anticipation of physical exercise or strong emotions by the limbic system Catecholamines Decreased epinephrine and norepinephrine release by the adrenal glands Thyroid hormones Increased T 3 and T 4 in the blood (released by thyroid) Calcium Decrease in calcium ions in the blood Potassium Decrease in potassium ions in the blood Sodium Decrease in sodium ions in the blood Body temperature Increase in body temperature Nicotine and caffeine Presence of nicotine, caffeine or other stimulants Table 19.1 Factors Decreasing Heart Rate and Force of Contraction Factor Effect Cardioinhibitor nerves (vagus) Release of acetylcholine by cardioaccelerator nerves Proprioreceptors Decreased firing rates of proprioreceptors (e.g. during rest) Chemoreceptors Chemoreceptors sensing increased levels of O 2 or decreased levels of H + , CO 2 and lactic acid Baroreceptors Increased firing rates of baroreceptors (indicating rising blood volume/pressure) Limbic system Anticipation of relaxation by the limbic system Catecholamines Decreased epinephrine and norepinephrine release by the adrenal glands Thyroid hormones Decreased T 3 and T 4 in the blood (released by thyroid) Calcium Decrease in calcium ions in the blood Potassium Increase in potassium ions in the blood Sodium Increase in sodium ions in the blood Body temperature Decrease in body temperature Opiates and tranquilizers Presence of opiates (heroin), tranquilizers or other depressants Table 19.2 Epinephrine and Norepinephrine The catecholamines, epinephrine and NE, secreted by the adrenal medulla form one component of the extended fight-or-flight mechanism. The other component is sympathetic stimulation. Epinephrine and NE have similar effects: binding to the beta-1 receptors, and opening sodium and calcium ion chemical- or ligand-gated channels. The rate of depolarization is increased by this additional influx of positively charged ions, so the threshold is reached more quickly and the period of repolarization is shortened. However, massive releases of these hormones coupled with sympathetic stimulation may actually lead to arrhythmias. There is no parasympathetic stimulation to the adrenal medulla. Thyroid Hormones In general, increased levels of thyroid hormone, or thyroxin, increase cardiac rate and contractility. The impact of thyroid hormone is typically of a much longer duration than that of the catecholamines. The physiologically active form of thyroid hormone, T 3 or triiodothyronine, has been shown to directly enter cardiomyocytes and alter activity at the level of the genome. It also impacts the beta adrenergic response similar to epinephrine and NE described above. Excessive levels of thyroxin may trigger tachycardia. Calcium Calcium ion levels have great impacts upon both HR and contractility; as the levels of calcium ions increase, so do HR and contractility. High levels of calcium ions (hypercalcemia) may be implicated in a short QT interval and a widened T wave in the ECG. The QT interval represents the time from the start of depolarization to repolarization of the ventricles, and includes the period of ventricular systole. Extremely high levels of calcium may induce cardiac arrest. Drugs known as calcium channel blockers slow HR by binding to these channels and blocking or slowing the inward movement of calcium ions. Caffeine and Nicotine Caffeine and nicotine are not found naturally within the body. Both of these nonregulated drugs have an excitatory effect on membranes of neurons in general and have a stimulatory effect on the cardiac centers specifically, causing an increase in HR. Caffeine works by increasing the rates of depolarization at the SA node, whereas nicotine stimulates the activity of the sympathetic neurons that deliver impulses to the heart. Although it is the world’s most widely consumed psychoactive drug, caffeine is legal and not regulated. While precise quantities have not been established, “normal” consumption is not considered harmful to most people, although it may cause disruptions to sleep and acts as a diuretic. Its consumption by pregnant women is cautioned against, although no evidence of negative effects has been confirmed. Tolerance and even physical and mental addiction to the drug result in individuals who routinely consume the substance. Nicotine, too, is a stimulant and produces addiction. While legal and nonregulated, concerns about nicotine’s safety and documented links to respiratory and cardiac disease have resulted in warning labels on cigarette packages. Factors Decreasing Heart Rate HR can be slowed when a person experiences altered sodium and potassium levels, hypoxia, acidosis, alkalosis, and hypothermia (see Table 19.1 ). The relationship between electrolytes and HR is complex, but maintaining electrolyte balance is critical to the normal wave of depolarization. Of the two ions, potassium has the greater clinical significance. Initially, both hyponatremia (low sodium levels) and hypernatremia (high sodium levels) may lead to tachycardia. Severely high hypernatremia may lead to fibrillation, which may cause CO to cease. Severe hyponatremia leads to both bradycardia and other arrhythmias. Hypokalemia (low potassium levels) also leads to arrhythmias, whereas hyperkalemia (high potassium levels) causes the heart to become weak and flaccid, and ultimately to fail. Acidosis is a condition in which excess hydrogen ions are present, and the patient’s blood expresses a low pH value. Alkalosis is a condition in which there are too few hydrogen ions, and the patient’s blood has an elevated pH. Normal blood pH falls in the range of 7.35–7.45, so a number lower than this range represents acidosis and a higher number represents alkalosis. Recall that enzymes are the regulators or catalysts of virtually all biochemical reactions; they are sensitive to pH and will change shape slightly with values outside their normal range. These variations in pH and accompanying slight physical changes to the active site on the enzyme decrease the rate of formation of the enzyme-substrate complex, subsequently decreasing the rate of many enzymatic reactions, which can have complex effects on HR. Severe changes in pH will lead to denaturation of the enzyme. The last variable is body temperature. Elevated body temperature is called hyperthermia, and suppressed body temperature is called hypothermia. Slight hyperthermia results in increasing HR and strength of contraction. Hypothermia slows the rate and strength of heart contractions. This distinct slowing of the heart is one component of the larger diving reflex that diverts blood to essential organs while submerged. If sufficiently chilled, the heart will stop beating, a technique that may be employed during open heart surgery. In this case, the patient’s blood is normally diverted to an artificial heart-lung machine to maintain the body’s blood supply and gas exchange until the surgery is complete, and sinus rhythm can be restored. Excessive hyperthermia and hypothermia will both result in death, as enzymes drive the body systems to cease normal function, beginning with the central nervous system. Stroke Volume Many of the same factors that regulate HR also impact cardiac function by altering SV. While a number of variables are involved, SV is ultimately dependent upon the difference between EDV and ESV. The three primary factors to consider are preload, or the stretch on the ventricles prior to contraction; the contractility, or the force or strength of the contraction itself; and afterload, the force the ventricles must generate to pump blood against the resistance in the vessels. These factors are summarized in Table 19.1 and Table 19.2 . Preload Preload is another way of expressing EDV. Therefore, the greater the EDV is, the greater the preload is. One of the primary factors to consider is filling time , or the duration of ventricular diastole during which filling occurs. The more rapidly the heart contracts, the shorter the filling time becomes, and the lower the EDV and preload are. This effect can be partially overcome by increasing the second variable, contractility, and raising SV, but over time, the heart is unable to compensate for decreased filling time, and preload also decreases. With increasing ventricular filling, both EDV or preload increase, and the cardiac muscle itself is stretched to a greater degree. At rest, there is little stretch of the ventricular muscle, and the sarcomeres remain short. With increased ventricular filling, the ventricular muscle is increasingly stretched and the sarcomere length increases. As the sarcomeres reach their optimal lengths, they will contract more powerfully, because more of the myosin heads can bind to the actin on the thin filaments, forming cross bridges and increasing the strength of contraction and SV. If this process were to continue and the sarcomeres stretched beyond their optimal lengths, the force of contraction would decrease. However, due to the physical constraints of the location of the heart, this excessive stretch is not a concern. The relationship between ventricular stretch and contraction has been stated in the well-known Frank-Starling mechanism or simply Starling’s Law of the Heart. This principle states that, within physiological limits, the force of heart contraction is directly proportional to the initial length of the muscle fiber. This means that the greater the stretch of the ventricular muscle (within limits), the more powerful the contraction is, which in turn increases SV. Therefore, by increasing preload, you increase the second variable, contractility. Otto Frank (1865–1944) was a German physiologist; among his many published works are detailed studies of this important heart relationship. Ernest Starling (1866–1927) was an important English physiologist who also studied the heart. Although they worked largely independently, their combined efforts and similar conclusions have been recognized in the name “Frank-Starling mechanism.” Any sympathetic stimulation to the venous system will increase venous return to the heart, which contributes to ventricular filling, and EDV and preload. While much of the ventricular filling occurs while both atria and ventricles are in diastole, the contraction of the atria, the atrial kick, plays a crucial role by providing the last 20–30 percent of ventricular filling. Contractility It is virtually impossible to consider preload or ESV without including an early mention of the concept of contractility. Indeed, the two parameters are intimately linked. Contractility refers to the force of the contraction of the heart muscle, which controls SV, and is the primary parameter for impacting ESV. The more forceful the contraction is, the greater the SV and smaller the ESV are. Less forceful contractions result in smaller SVs and larger ESVs. Factors that increase contractility are described as positive inotropic factors , and those that decrease contractility are described as negative inotropic factors (ino- = “fiber;” -tropic = “turning toward”). Not surprisingly, sympathetic stimulation is a positive inotrope, whereas parasympathetic stimulation is a negative inotrope. Sympathetic stimulation triggers the release of NE at the neuromuscular junction from the cardiac nerves and also stimulates the adrenal cortex to secrete epinephrine and NE. In addition to their stimulatory effects on HR, they also bind to both alpha and beta receptors on the cardiac muscle cell membrane to increase metabolic rate and the force of contraction. This combination of actions has the net effect of increasing SV and leaving a smaller residual ESV in the ventricles. In comparison, parasympathetic stimulation releases ACh at the neuromuscular junction from the vagus nerve. The membrane hyperpolarizes and inhibits contraction to decrease the strength of contraction and SV, and to raise ESV. Since parasympathetic fibers are more widespread in the atria than in the ventricles, the primary site of action is in the upper chambers. Parasympathetic stimulation in the atria decreases the atrial kick and reduces EDV, which decreases ventricular stretch and preload, thereby further limiting the force of ventricular contraction. Stronger parasympathetic stimulation also directly decreases the force of contraction of the ventricles. Several synthetic drugs, including dopamine and isoproterenol, have been developed that mimic the effects of epinephrine and NE by stimulating the influx of calcium ions from the extracellular fluid. Higher concentrations of intracellular calcium ions increase the strength of contraction. Excess calcium (hypercalcemia) also acts as a positive inotropic agent. The drug digitalis lowers HR and increases the strength of the contraction, acting as a positive inotropic agent by blocking the sequestering of calcium ions into the sarcoplasmic reticulum. This leads to higher intracellular calcium levels and greater strength of contraction. In addition to the catecholamines from the adrenal medulla, other hormones also demonstrate positive inotropic effects. These include thyroid hormones and glucagon from the pancreas. Negative inotropic agents include hypoxia, acidosis, hyperkalemia, and a variety of synthetic drugs. These include numerous beta blockers and calcium channel blockers. Early beta blocker drugs include propranolol and pronethalol, and are credited with revolutionizing treatment of cardiac patients experiencing angina pectoris. There is also a large class of dihydropyridine, phenylalkylamine, and benzothiazepine calcium channel blockers that may be administered decreasing the strength of contraction and SV. Afterload Afterload refers to the tension that the ventricles must develop to pump blood effectively against the resistance in the vascular system. Any condition that increases resistance requires a greater afterload to force open the semilunar valves and pump the blood. Damage to the valves, such as stenosis, which makes them harder to open will also increase afterload. Any decrease in resistance decreases the afterload. Figure 19.34 summarizes the major factors influencing SV, Figure 19.35 summarizes the major factors influencing CO, and Table 19.3 and Table 19.4 summarize cardiac responses to increased and decreased blood flow and pressure in order to restore homeostasis. Cardiac Response to Decreasing Blood Flow and Pressure Due to Decreasing Cardiac Output Baroreceptors (aorta, carotid arteries, venae cavae, and atria) Chemoreceptors (both central nervous system and in proximity to baroreceptors) Sensitive to Decreasing stretch Decreasing O 2 and increasing CO 2 , H + , and lactic acid Target Parasympathetic stimulation suppressed Sympathetic stimulation increased Response of heart Increasing heart rate and increasing stroke volume Increasing heart rate and increasing stroke volume Overall effect Increasing blood flow and pressure due to increasing cardiac output; homeostasis restored Increasing blood flow and pressure due to increasing cardiac output; homeostasis restored Table 19.3 Cardiac Response to Increasing Blood Flow and Pressure Due to Increasing Cardiac Output Baroreceptors (aorta, carotid arteries, venae cavae, and atria) Chemoreceptors (both central nervous system and in proximity to baroreceptors) Sensitive to Increasing stretch Increasing O 2 and decreasing CO 2 , H + , and lactic acid Target Parasympathetic stimulation increased Sympathetic stimulation suppressed Response of heart Decreasing heart rate and decreasing stroke volume Decreasing heart rate and decreasing stroke volume Overall effect Decreasing blood flow and pressure due to decreasing cardiac output; homeostasis restored Decreasing blood flow and pressure due to decreasing cardiac output; homeostasis restored Table 19.4 19.5 Development of the Heart Learning Objectives By the end of this section, you will be able to: Describe the embryological development of heart structures Identify five regions of the fetal heart Relate fetal heart structures to adult counterparts The human heart is the first functional organ to develop. It begins beating and pumping blood around day 21 or 22, a mere three weeks after fertilization. This emphasizes the critical nature of the heart in distributing blood through the vessels and the vital exchange of nutrients, oxygen, and wastes both to and from the developing baby. The critical early development of the heart is reflected by the prominent heart bulge that appears on the anterior surface of the embryo. The heart forms from an embryonic tissue called mesoderm around 18 to 19 days after fertilization. Mesoderm is one of the three primary germ layers that differentiates early in development that collectively gives rise to all subsequent tissues and organs. The heart begins to develop near the head of the embryo in a region known as the cardiogenic area . Following chemical signals called factors from the underlying endoderm (another of the three primary germ layers), the cardiogenic area begins to form two strands called the cardiogenic cords ( Figure 19.36 ). As the cardiogenic cords develop, a lumen rapidly develops within them. At this point, they are referred to as endocardial tubes . The two tubes migrate together and fuse to form a single primitive heart tube . The primitive heart tube quickly forms five distinct regions. From head to tail, these include the truncus arteriosus, bulbus cordis, primitive ventricle, primitive atrium, and the sinus venosus. Initially, all venous blood flows into the sinus venosus, and contractions propel the blood from tail to head, or from the sinus venosus to the truncus arteriosus. This is a very different pattern from that of an adult. The five regions of the primitive heart tube develop into recognizable structures in a fully developed heart. The truncus arteriosus will eventually divide and give rise to the ascending aorta and pulmonary trunk. The bulbus cordis develops into the right ventricle. The primitive ventricle forms the left ventricle. The primitive atrium becomes the anterior portions of both the right and left atria, and the two auricles. The sinus venosus develops into the posterior portion of the right atrium, the SA node, and the coronary sinus. As the primitive heart tube elongates, it begins to fold within the pericardium, eventually forming an S shape, which places the chambers and major vessels into an alignment similar to the adult heart. This process occurs between days 23 and 28. The remainder of the heart development pattern includes development of septa and valves, and remodeling of the actual chambers. Partitioning of the atria and ventricles by the interatrial septum, interventricular septum, and atrioventricular septum is complete by the end of the fifth week, although the fetal blood shunts remain until birth or shortly after. The atrioventricular valves form between weeks five and eight, and the semilunar valves form between weeks five and nine.
microbiology
Summary 14.1 History of Chemotherapy and Antimicrobial Discovery Antimicrobial drugs produced by purposeful fermentation and/or contained in plants have been used as traditional medicines in many cultures for millennia. The purposeful and systematic search for a chemical “magic bullet” that specifically target infectious microbes was initiated by Paul Ehrlich in the early 20th century. The discovery of the natural antibiotic , penicillin, by Alexander Fleming in 1928 started the modern age of antimicrobial discovery and research. Sulfanilamide, the first synthetic antimicrobial , was discovered by Gerhard Domagk and colleagues and is a breakdown product of the synthetic dye, prontosil. 14.2 Fundamentals of Antimicrobial Chemotherapy Antimicrobial drugs can be bacteriostatic or bactericidal , and these characteristics are important considerations when selecting the most appropriate drug. The use of narrow-spectrum antimicrobial drugs is preferred in many cases to avoid superinfection and the development of antimicrobial resistance. Broad-spectrum antimicrobial use is warranted for serious systemic infections when there is no time to determine the causative agent, when narrow-spectrum antimicrobials fail, or for the treatment or prevention of infections with multiple types of microbes. The dosage and route of administration are important considerations when selecting an antimicrobial to treat and infection. Other considerations include the patient’s age, mass, ability to take oral medications, liver and kidney function, and possible interactions with other drugs the patient may be taking. 14.3 Mechanisms of Antibacterial Drugs Antibacterial compounds exhibit selective toxicity , largely due to differences between prokaryotic and eukaryotic cell structure. Cell wall synthesis inhibitors, including the β-lactams , the glycopeptides , and bacitracin , interfere with peptidoglycan synthesis, making bacterial cells more prone to osmotic lysis. There are a variety of broad-spectrum, bacterial protein synthesis inhibitors that selectively target the prokaryotic 70S ribosome, including those that bind to the 30S subunit ( aminoglycosides and tetracyclines ) and others that bind to the 50S subunit ( macrolides , lincosamides , chloramphenicol , and oxazolidinones ). Polymyxins are lipophilic polypeptide antibiotics that target the lipopolysaccharide component of gram-negative bacteria and ultimately disrupt the integrity of the outer and inner membranes of these bacteria. The nucleic acid synthesis inhibitors rifamycins and fluoroquinolones target bacterial RNA transcription and DNA replication, respectively. Some antibacterial drugs are antimetabolites , acting as competitive inhibitors for bacterial metabolic enzymes. Sulfonamides and trimethoprim are antimetabolites that interfere with bacterial folic acid synthesis. Isoniazid is an antimetabolite that interferes with mycolic acid synthesis in mycobacteria. 14.4 Mechanisms of Other Antimicrobial Drugs Because fungi, protozoans, and helminths are eukaryotic organisms like human cells, it is more challenging to develop antimicrobial drugs that specifically target them. Similarly, it is hard to target viruses because human viruses replicate inside of human cells. Antifungal drugs interfere with ergosterol synthesis, bind to ergosterol to disrupt fungal cell membrane integrity, or target cell wall-specific components or other cellular proteins. Antiprotozoan drugs increase cellular levels of reactive oxygen species, interfere with protozoal DNA replication (nuclear versus kDNA, respectively), and disrupt heme detoxification. Antihelminthic drugs disrupt helminthic and protozoan microtubule formation; block neuronal transmissions; inhibit anaerobic ATP formation and/or oxidative phosphorylation; induce a calcium influx in tapeworms, leading to spasms and paralysis; and interfere with RNA synthesis in schistosomes. Antiviral drugs inhibit viral entry, inhibit viral uncoating, inhibit nucleic acid biosynthesis, prevent viral escape from endosomes in host cells, and prevent viral release from infected cells. Because it can easily mutate to become drug resistant, HIV is typically treated with a combination of several antiretroviral drugs , which may include reverse transcriptase inhibitors, protease inhibitors, integrase inhibitors , and drugs that interfere with viral binding and fusion to initiate infection. 14.5 Drug Resistance Antimicrobial resistance is on the rise and is the result of selection of drug-resistant strains in clinical environments, the overuse and misuse of antibacterials, the use of subtherapeutic doses of antibacterial drugs, and poor patient compliance with antibacterial drug therapies. Drug resistance genes are often carried on plasmids or in transposons that can undergo vertical transfer easily and between microbes through horizontal gene transfer. Common modes of antimicrobial drug resistance include drug modification or inactivation, prevention of cellular uptake or efflux, target modification, target overproduction or enzymatic bypass, and target mimicry. Problematic microbial strains showing extensive antimicrobial resistance are emerging; many of these strains can reside as members of the normal microbiota in individuals but also can cause opportunistic infection. The transmission of many of these highly resistant microbial strains often occurs in clinical settings, but can also be community-acquired. 14.6 Testing the Effectiveness of Antimicrobials The Kirby-Bauer disk diffusion test helps determine the susceptibility of a microorganism to various antimicrobial drugs. However, the zones of inhibition measured must be correlated to known standards to determine susceptibility and resistance, and do not provide information on bactericidal versus bacteriostatic activity, or allow for direct comparison of drug potencies. Antibiograms are useful for monitoring local trends in antimicrobial resistance/susceptibility and for directing appropriate selection of empiric antibacterial therapy. There are several laboratory methods available for determining the minimum inhibitory concentration (MIC) of an antimicrobial drug against a specific microbe. The minimal bactericidal concentration (MBC) can also be determined, typically as a follow-up experiment to MIC determination using the tube dilution method. 14.7 Current Strategies for Antimicrobial Discovery Current research into the development of antimicrobial drugs involves the use of high-throughput screening and combinatorial chemistry technologies. New technologies are being developed to discover novel antibiotics from soil microorganisms that cannot be cultured by standard laboratory methods. Additional strategies include searching for antibiotics from sources other than soil, identifying new antibacterial targets, using combinatorial chemistry to develop novel drugs, developing drugs that inhibit resistance mechanisms, and developing drugs that target virulence factors and hold infections in check.
Chapter Outline 14.1 History of Chemotherapy and Antimicrobial Discovery 14.2 Fundamentals of Antimicrobial Chemotherapy 14.3 Mechanisms of Antibacterial Drugs 14.4 Mechanisms of Other Antimicrobial Drugs 14.5 Drug Resistance 14.6 Testing the Effectiveness of Antimicrobials 14.7 Current Strategies for Antimicrobial Discovery Introduction In nature, some microbes produce substances that inhibit or kill other microbes that might otherwise compete for the same resources. Humans have successfully exploited these abilities, using microbes to mass-produce substances that can be used as antimicrobial drugs. Since their discovery, antimicrobial drugs have saved countless lives, and they remain an essential tool for treating and controlling infectious disease. But their widespread and often unnecessary use has had an unintended side effect: the rise of multidrug-resistant microbial strains. In this chapter, we will discuss how antimicrobial drugs work, why microbes develop resistance, and what health professionals can do to encourage responsible use of antimicrobials.
[ { "answer": { "ans_choice": 0, "ans_text": "A" }, "bloom": null, "hl_context": "A few decades later , German scientists Josef Klarer , Fritz Mietzsch , and Gerhard Domagk discovered the antibacterial activity of a synthetic dye , prontosil , that could treat streptococcal and staphylococcal infections in mice . Domagk ’ s own daughter was one of the first human recipients of the drug , which completely cured her of a severe streptococcal infection that had resulted from a poke with an embroidery needle . Gerhard Domagk ( 1895 – 1964 ) was awarded the Nobel Prize in Medicine in 1939 for his work with prontosil and sulfanilamide , the active breakdown product of prontosil in the body . <hl> Sulfanilamide , the first synthetic antimicrobial created , served as the foundation for the chemical development of a family of sulfa drugs . <hl> A synthetic antimicrobial is a drug that is developed from a chemical not found in nature . The success of the sulfa drugs led to the discovery and production of additional important classes of synthetic antimicrobials , including the quinolines and oxazolidinones .", "hl_sentences": "Sulfanilamide , the first synthetic antimicrobial created , served as the foundation for the chemical development of a family of sulfa drugs .", "question": { "cloze_format": "The antimicrobial drug ___ is synthetic.", "normal_format": "Which of the following antimicrobial drugs is synthetic?", "question_choices": [ "sulfanilamide", "penicillin", "actinomycin", "neomycin" ], "question_id": "fs-id1167659391042", "question_text": "Which of the following antimicrobial drugs is synthetic?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 1, "ans_text": "B" }, "bloom": null, "hl_context": "<hl> The risk associated with using broad-spectrum antimicrobials is that they will also target a broad spectrum of the normal microbiota , increasing the risk of a superinfection , a secondary infection in a patient having a preexisting infection . <hl> <hl> A superinfection develops when the antibacterial intended for the preexisting infection kills the protective microbiota , allowing another pathogen resistant to the antibacterial to proliferate and cause a secondary infection ( Figure 14.6 ) . <hl> Common examples of superinfections that develop as a result of antimicrobial usage include yeast infections ( candidiasis ) and pseudomembranous colitis caused by Clostridium difficile , which can be fatal .", "hl_sentences": "The risk associated with using broad-spectrum antimicrobials is that they will also target a broad spectrum of the normal microbiota , increasing the risk of a superinfection , a secondary infection in a patient having a preexisting infection . A superinfection develops when the antibacterial intended for the preexisting infection kills the protective microbiota , allowing another pathogen resistant to the antibacterial to proliferate and cause a secondary infection ( Figure 14.6 ) .", "question": { "cloze_format": "The combination that would most likely contribute to the development of a superinfection is the ___ .", "normal_format": "Which of the following combinations would most likely contribute to the development of a superinfection?", "question_choices": [ "long-term use of narrow-spectrum antimicrobials", "long-term use of broad-spectrum antimicrobials", "short-term use of narrow-spectrum antimicrobials", "short-term use of broad-spectrum antimicrobials" ], "question_id": "fs-id1167660261866", "question_text": "Which of the following combinations would most likely contribute to the development of a superinfection?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 0, "ans_text": "A" }, "bloom": null, "hl_context": "<hl> The route of administration , the method used to introduce a drug into the body , is also an important consideration for drug therapy . <hl> <hl> Drugs that can be administered orally are generally preferred because patients can more conveniently take these drugs at home . <hl> However , some drugs are not absorbed easily from the gastrointestinal ( GI ) tract into the bloodstream . These drugs are often useful for treating diseases of the intestinal tract , such as tapeworms treated with niclosamide , or for decontaminating the bowel , as with colistin . Some drugs that are not absorbed easily , such as bacitracin , polymyxin , and several antifungals , are available as topical preparations for treatment of superficial skin infections . Sometimes , patients may not initially be able to take oral medications because of their illness ( e . g . , vomiting , intubation for respirator ) . When this occurs , and when a chosen drug is not absorbed in the GI tract , administration of the drug by a parenteral route ( intravenous or intramuscular injection ) is preferred and typically is performed in health-care settings . For most drugs , the plasma levels achieved by intravenous administration is substantially higher than levels achieved by oral or intramuscular administration , and this can also be an important consideration when choosing the route of administration for treating an infection ( Figure 14.7 ) .", "hl_sentences": "The route of administration , the method used to introduce a drug into the body , is also an important consideration for drug therapy . Drugs that can be administered orally are generally preferred because patients can more conveniently take these drugs at home .", "question": { "cloze_format": "The route of administration that would be appropriate and convenient for home administration of an antimicrobial to treat a systemic infection is ___.", "normal_format": "Which of the following routes of administration would be appropriate and convenient for home administration of an antimicrobial to treat a systemic infection?", "question_choices": [ "oral", "intravenous", "topical", "parenteral" ], "question_id": "fs-id1167660323716", "question_text": "Which of the following routes of administration would be appropriate and convenient for home administration of an antimicrobial to treat a systemic infection?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 2, "ans_text": "C" }, "bloom": null, "hl_context": "The spectrum of activity of an antibacterial drug relates to diversity of targeted bacteria . A narrow-spectrum antimicrobial targets only specific subsets of bacterial pathogens . For example , some narrow-spectrum drugs only target gram-positive bacteria , whereas others target only gram-negative bacteria . <hl> If the pathogen causing an infection has been identified , it is best to use a narrow-spectrum antimicrobial and minimize collateral damage to the normal microbiota . <hl> A broad-spectrum antimicrobial targets a wide variety of bacterial pathogens , including both gram-positive and gram-negative species , and is frequently used as empiric therapy to cover a wide range of potential pathogens while waiting on the laboratory identification of the infecting pathogen . Broad-spectrum antimicrobials are also used for polymicrobic infections ( mixed infection with multiple bacterial species ) , or as prophylactic prevention of infections with surgery / invasive procedures . Finally , broad-spectrum antimicrobials may be selected to treat an infection when a narrow-spectrum drug fails because of development of drug resistance by the target pathogen . Most people associate the term chemotherapy with treatments for cancer . However , chemotherapy is actually a broader term that refers to any use of chemicals or drugs to treat disease . Chemotherapy may involve drugs that target cancerous cells or tissues , or it may involve antimicrobial drugs that target infectious microorganisms . <hl> Antimicrobial drugs typically work by destroying or interfering with microbial structures and enzymes , either killing microbial cells or inhibiting of their growth . <hl> But before we examine how these drugs work , we will briefly explore the history of humans ’ use of antimicrobials for the purpose of chemotherapy .", "hl_sentences": "If the pathogen causing an infection has been identified , it is best to use a narrow-spectrum antimicrobial and minimize collateral damage to the normal microbiota . Antimicrobial drugs typically work by destroying or interfering with microbial structures and enzymes , either killing microbial cells or inhibiting of their growth .", "question": { "cloze_format": "The clinical situation that would be appropriate for treatment with a narrow-spectrum antimicrobial drug is ___ .", "normal_format": "Which clinical situation would be appropriate for treatment with a narrow-spectrum antimicrobial drug?", "question_choices": [ "treatment of a polymicrobic mixed infection in the intestine", "prophylaxis against infection after a surgical procedure", "treatment of strep throat caused by culture identified Streptococcus pyogenes", "empiric therapy of pneumonia while waiting for culture results" ], "question_id": "fs-id1167660131926", "question_text": "Which clinical situation would be appropriate for treatment with a narrow-spectrum antimicrobial drug?" }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 3, "ans_text": "D" }, "bloom": null, "hl_context": "<hl> An important quality for an antimicrobial drug is selective toxicity , meaning that it selectively kills or inhibits the growth of microbial targets while causing minimal or no harm to the host . <hl> Most antimicrobial drugs currently in clinical use are antibacterial because the prokaryotic cell provides a greater variety of unique targets for selective toxicity , in comparison to fungi , parasites , and viruses . Each class of antibacterial drugs has a unique mode of action ( the way in which a drug affects microbes at the cellular level ) , and these are summarized in Figure 14.9 and Table 14.1 .", "hl_sentences": "An important quality for an antimicrobial drug is selective toxicity , meaning that it selectively kills or inhibits the growth of microbial targets while causing minimal or no harm to the host .", "question": { "cloze_format": "The terms that refers to the ability of an antimicrobial drug to harm the target microbe without harming the host is ___.", "normal_format": "Which of the following terms refers to the ability of an antimicrobial drug to harm the target microbe without harming the host?", "question_choices": [ "mode of action", "therapeutic level", "spectrum of activity", "selective toxicity" ], "question_id": "fs-id1167661429067", "question_text": "Which of the following terms refers to the ability of an antimicrobial drug to harm the target microbe without harming the host?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 1, "ans_text": "B" }, "bloom": null, "hl_context": "<hl> Similar to the penicillins , cephalosporins contain a β-lactam ring ( Figure 14.10 ) and block the transpeptidase activity of penicillin-binding proteins . <hl> However , the β-lactam ring of cephalosporins is fused to a six-member ring , rather than the five-member ring found in penicillins . This chemical difference provides cephalosporins with an increased resistance to enzymatic inactivation by β-lactamases . The drug cephalosporin C was originally isolated from the fungus Cephalosporium acremonium in the 1950s and has a similar spectrum of activity to that of penicillin against gram-positive bacteria but is active against more gram-negative bacteria than penicillin . Another important structural difference is that cephalosporin C possesses two R groups , compared with just one R group for penicillin , and this provides for greater diversity in chemical alterations and development of semisynthetic cephalosporins . The family of semisynthetic cephalosporins is much larger than the penicillins , and these drugs have been classified into generations based primarily on their spectrum of activity , increasing in spectrum from the narrow-spectrum , first-generation cephalosporins to the broad-spectrum , fourth-generation cephalosporins . A new fifth-generation cephalosporin has been developed that is active against methicillin-resistant Staphylococcus aureus ( MRSA ) . <hl> Penicillin , the first antibiotic discovered , is one of several antibacterials within a class called β-lactams . <hl> <hl> This group of compounds includes the penicillins , cephalosporins , monobactams , and carbapenems , and is characterized by the presence of a β-lactam ring found within the central structure of the drug molecule ( Figure 14.10 ) . <hl> The β-lactam antibacterials block the crosslinking of peptide chains during the biosynthesis of new peptidoglycan in the bacterial cell wall . They are able to block this process because the β-lactam structure is similar to the structure of the peptidoglycan subunit component that is recognized by the crosslinking transpeptidase enzyme , also known as a penicillin-binding protein ( PBP ) . Although the β-lactam ring must remain unchanged for these drugs to retain their antibacterial activity , strategic chemical changes to the R groups have allowed for development of a wide variety of semisynthetic β-lactam drugs with increased potency , expanded spectrum of activity , and longer half-lives for better dosing , among other characteristics .", "hl_sentences": "Similar to the penicillins , cephalosporins contain a β-lactam ring ( Figure 14.10 ) and block the transpeptidase activity of penicillin-binding proteins . Penicillin , the first antibiotic discovered , is one of several antibacterials within a class called β-lactams . This group of compounds includes the penicillins , cephalosporins , monobactams , and carbapenems , and is characterized by the presence of a β-lactam ring found within the central structure of the drug molecule ( Figure 14.10 ) .", "question": { "cloze_format": "___ is not a type of β-lactam antimicrobial.", "normal_format": "Which of the following is not a type of β-lactam antimicrobial?", "question_choices": [ "penicillins", "glycopeptides", "cephalosporins", "monobactams" ], "question_id": "fs-id1167661298496", "question_text": "Which of the following is not a type of β-lactam antimicrobial?" }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 0, "ans_text": "A" }, "bloom": null, "hl_context": "<hl> The drug chloramphenicol represents yet another structurally distinct class of antibacterials that also bind to the 50S ribosome , inhibiting peptide bond formation . <hl> Chloramphenicol , produced by Streptomyces venezuelae , was discovered in 1947 ; in 1949 , it became the first broad-spectrum antibiotic that was approved by the FDA . Although it is a natural antibiotic , it is also easily synthesized and was the first antibacterial drug synthetically mass produced . As a result of its mass production , broad-spectrum coverage , and ability to penetrate into tissues efficiently , chloramphenicol was historically used to treat a wide range of infections , from meningitis to typhoid fever to conjunctivitis . Unfortunately , serious side effects , such as lethal gray baby syndrome , and suppression of bone marrow production , have limited its clinical role . Chloramphenicol also causes anemia in two different ways . <hl> One mechanism involves the targeting of mitochondrial ribosomes within hematopoietic stem cells , causing a reversible , dose-dependent suppression of blood cell production . <hl> Once chloramphenicol dosing is discontinued , blood cell production returns to normal . This mechanism highlights the similarity between 70S ribosomes of bacteria and the 70S ribosomes within our mitochondria . The second mechanism of anemia is idiosyncratic ( i . e . , the mechanism is not understood ) , and involves an irreversible lethal loss of blood cell production known as aplastic anemia . This mechanism of aplastic anemia is not dose dependent and can develop after therapy has stopped . Because of toxicity concerns , chloramphenicol usage in humans is now rare in the United States and is limited to severe infections unable to be treated by less toxic antibiotics . Because its side effects are much less severe in animals , it is used in veterinary medicine . <hl> The lincosamides include the naturally produced lincomycin and semisynthetic clindamycin . <hl> <hl> Although structurally distinct from macrolides , lincosamides are similar in their mode of action to the macrolides through binding to the 50S ribosomal subunit and preventing peptide bond formation . <hl> Lincosamides are particularly active against streptococcal and staphylococcal infections .", "hl_sentences": "The drug chloramphenicol represents yet another structurally distinct class of antibacterials that also bind to the 50S ribosome , inhibiting peptide bond formation . One mechanism involves the targeting of mitochondrial ribosomes within hematopoietic stem cells , causing a reversible , dose-dependent suppression of blood cell production . The lincosamides include the naturally produced lincomycin and semisynthetic clindamycin . Although structurally distinct from macrolides , lincosamides are similar in their mode of action to the macrolides through binding to the 50S ribosomal subunit and preventing peptide bond formation .", "question": { "cloze_format": "___ does not bind to the 50S ribosomal subunit.", "normal_format": "Which of the following does not bind to the 50S ribosomal subunit?", "question_choices": [ "tetracyclines", "lincosamides", "macrolides", "chloramphenicol" ], "question_id": "fs-id1167661403800", "question_text": "Which of the following does not bind to the 50S ribosomal subunit?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 2, "ans_text": "C" }, "bloom": null, "hl_context": "One member of the quinolone family , a group of synthetic antimicrobials , is nalidixic acid . It was discovered in 1962 as a byproduct during the synthesis of chloroquine , an antimalarial drug . <hl> Nalidixic acid selectively inhibits the activity of bacterial DNA gyrase , blocking DNA replication . <hl> Chemical modifications to the original quinolone backbone have resulted in the production of fluoroquinolones , like ciprofloxacin and levofloxacin , which also inhibit the activity of DNA gyrase . Ciprofloxacin and levofloxacin are effective against a broad spectrum of gram-positive or gram-negative bacteria , and are among the most commonly prescribed antibiotics used to treat a wide range of infections , including urinary tract infections , respiratory infections , abdominal infections , and skin infections . However , despite their selective toxicity against DNA gyrase , side effects associated with different fluoroquinolones include phototoxicity , neurotoxicity , cardiotoxicity , glucose metabolism dysfunction , and increased risk for tendon rupture .", "hl_sentences": "Nalidixic acid selectively inhibits the activity of bacterial DNA gyrase , blocking DNA replication .", "question": { "cloze_format": "The antimicrobial that inhibits the activity of DNA gyrase is ___ .", "normal_format": "Which of the following antimicrobials inhibits the activity of DNA gyrase?", "question_choices": [ "polymyxin B", "clindamycin", "nalidixic acid", "rifampin" ], "question_id": "fs-id1167661401393", "question_text": "Which of the following antimicrobials inhibits the activity of DNA gyrase?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 2, "ans_text": "C" }, "bloom": null, "hl_context": "<hl> Beyond targeting ergosterol in fungal cell membranes , there are a few antifungal drugs that target other fungal structures ( Figure 14.14 ) . <hl> The echinocandins , including caspofungin , are a group of naturally produced antifungal compounds that block the synthesis of β ( 1 → 3 ) glucan found in fungal cell walls but not found in human cells . This drug class has the nickname “ penicillin for fungi . ” Caspofungin is used for the treatment of aspergillosis as well as systemic yeast infections . The most common mode of action for antifungal drugs is the disruption of the cell membrane . Antifungals take advantage of small differences between fungi and humans in the biochemical pathways that synthesize sterols . The sterols are important in maintaining proper membrane fluidity and , hence , proper function of the cell membrane . For most fungi , the predominant membrane sterol is ergosterol . <hl> Because human cell membranes use cholesterol , instead of ergosterol , antifungal drugs that target ergosterol synthesis are selectively toxic ( Figure 14.13 ) . <hl>", "hl_sentences": "Beyond targeting ergosterol in fungal cell membranes , there are a few antifungal drugs that target other fungal structures ( Figure 14.14 ) . Because human cell membranes use cholesterol , instead of ergosterol , antifungal drugs that target ergosterol synthesis are selectively toxic ( Figure 14.13 ) .", "question": { "cloze_format": "___ is not an appropriate target for antifungal drugs.", "normal_format": "Which of the following is not an appropriate target for antifungal drugs?", "question_choices": [ "ergosterol", "chitin", "cholesterol", "β(1→3) glucan" ], "question_id": "fs-id1167661364965", "question_text": "Which of the following is not an appropriate target for antifungal drugs?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 1, "ans_text": "B" }, "bloom": null, "hl_context": "<hl> The avermectins are members of the macrolide family that were first discovered from a Japanese soil isolate , Streptomyces avermectinius . <hl> <hl> A more potent semisynthetic derivative of avermectin is ivermectin , which binds to glutamate-gated chloride channels specific to invertebrates including helminths , blocking neuronal transmission and causing starvation , paralysis , and death of the worms . <hl> Ivermectin is used to treat roundworm diseases , including onchocerciasis ( also called river blindness , caused by the worm Onchocerca volvulus ) and strongyloidiasis ( caused by the worm Strongyloides stercoralis or S . fuelleborni ) . Ivermectin also can also treat parasitic insects like mites , lice , and bed bugs , and is nontoxic to humans .", "hl_sentences": "The avermectins are members of the macrolide family that were first discovered from a Japanese soil isolate , Streptomyces avermectinius . A more potent semisynthetic derivative of avermectin is ivermectin , which binds to glutamate-gated chloride channels specific to invertebrates including helminths , blocking neuronal transmission and causing starvation , paralysis , and death of the worms .", "question": { "cloze_format": "The drug class that specifically inhibits neuronal transmission in helminths is ___.", "normal_format": "Which of the following drug classes specifically inhibits neuronal transmission in helminths?", "question_choices": [ "quinolines", "avermectins", "amantadines", "imidazoles" ], "question_id": "fs-id1167664003689", "question_text": "Which of the following drug classes specifically inhibits neuronal transmission in helminths?" }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 3, "ans_text": "D" }, "bloom": null, "hl_context": "<hl> The reverse transcriptase inhibitors block the early step of converting viral RNA genome into DNA , and can include competitive nucleoside analog inhibitors ( e . g . , azidothymidine / zidovudine , or AZT ) and non-nucleoside noncompetitive inhibitors ( e . g . , etravirine ) that bind reverse transcriptase and cause an inactivating conformational change . <hl> Drugs called protease inhibitors ( e . g . , ritonavir ) block the processing of viral proteins and prevent viral maturation . Protease inhibitors are also being developed for the treatment of other viral types . 18 For example , simeprevir ( Olysio ) has been approved for the treatment of hepatitis C and is administered with ribavirin and interferon in combination therapy . The integrase inhibitors ( e . g . , raltegravir ) , block the activity of the HIV integrase responsible for the recombination of a DNA copy of the viral genome into the host cell chromosome . Additional drug classes for HIV treatment include the CCR 5 antagonists and the fusion inhibitors ( e . g . , enfuviritide ) , which prevent the binding of HIV to the host cell coreceptor ( chemokine receptor type 5 [ CCR 5 ] ) and the merging of the viral envelope with the host cell membrane , respectively . Table 14.10 shows the various therapeutic classes of antiviral drugs , categorized by mode of action , with examples of each . 18 B . L . Pearlman . “ Protease Inhibitors for the Treatment of Chronic Hepatitis C Genotype - 1 Infection : The New Standard of Care . ” Lancet Infectious Diseases 12 no . 9 ( 2012 ): 717 – 728 .", "hl_sentences": "The reverse transcriptase inhibitors block the early step of converting viral RNA genome into DNA , and can include competitive nucleoside analog inhibitors ( e . g . , azidothymidine / zidovudine , or AZT ) and non-nucleoside noncompetitive inhibitors ( e . g . , etravirine ) that bind reverse transcriptase and cause an inactivating conformational change .", "question": { "cloze_format": "___ is a nucleoside analog commonly used as a reverse transcriptase inhibitor in the treatment of HIV.", "normal_format": "Which of the following is a nucleoside analog commonly used as a reverse transcriptase inhibitor in the treatment of HIV?", "question_choices": [ "acyclovir", "ribavirin", "adenine-arabinoside", "azidothymidine" ], "question_id": "fs-id1167661294856", "question_text": "Which of the following is a nucleoside analog commonly used as a reverse transcriptase inhibitor in the treatment of HIV?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 0, "ans_text": "A" }, "bloom": null, "hl_context": "<hl> Artemisinin , a plant-derived antifungal first discovered by Chinese scientists in the 1970s , is quite effective against malaria . <hl> Semisynthetic derivatives of artemisinin are more water soluble than the natural version , which makes them more bioavailable . <hl> Although the exact mechanism of action is unclear , artemisinins appear to act as prodrugs that are metabolized by target cells to produce reactive oxygen species ( ROS ) that damage target cells . <hl> Due to the rise in resistance to antimalarial drugs , artemisinins are also commonly used in combination with other antimalarial compounds in artemisinin-based combination therapy ( ACT ) .", "hl_sentences": "Artemisinin , a plant-derived antifungal first discovered by Chinese scientists in the 1970s , is quite effective against malaria . Although the exact mechanism of action is unclear , artemisinins appear to act as prodrugs that are metabolized by target cells to produce reactive oxygen species ( ROS ) that damage target cells .", "question": { "cloze_format": "___ is an antimalarial drug that is thought to increase ROS levels in target cells.", "normal_format": "Which of the following is an antimalarial drug that is thought to increase ROS levels in target cells?", "question_choices": [ "artemisinin", "amphotericin b", "praziquantel", "pleconaril" ], "question_id": "fs-id1167659329127", "question_text": "Which of the following is an antimalarial drug that is thought to increase ROS levels in target cells?" }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 2, "ans_text": "C" }, "bloom": null, "hl_context": "<hl> Resistance genes may code for enzymes that chemically modify an antimicrobial , thereby inactivating it , or destroy an antimicrobial through hydrolysis . <hl> Resistance to many types of antimicrobials occurs through this mechanism . For example , aminoglycoside resistance can occur through enzymatic transfer of chemical groups to the drug molecule , impairing the binding of the drug to its bacterial target . For β-lactams , bacterial resistance can involve the enzymatic hydrolysis of the β-lactam bond within the β-lactam ring of the drug molecule . Once the β-lactam bond is broken , the drug loses its antibacterial activity . <hl> This mechanism of resistance is mediated by β-lactamases , which are the most common mechanism of β-lactam resistance . <hl> <hl> Inactivation of rifampin commonly occurs through glycosylation , phosphorylation , or adenosine diphosphate ( ADP ) ribosylation , and resistance to macrolides and lincosamides can also occur due to enzymatic inactivation of the drug or modification . <hl>", "hl_sentences": "Resistance genes may code for enzymes that chemically modify an antimicrobial , thereby inactivating it , or destroy an antimicrobial through hydrolysis . This mechanism of resistance is mediated by β-lactamases , which are the most common mechanism of β-lactam resistance . Inactivation of rifampin commonly occurs through glycosylation , phosphorylation , or adenosine diphosphate ( ADP ) ribosylation , and resistance to macrolides and lincosamides can also occur due to enzymatic inactivation of the drug or modification .", "question": { "cloze_format": "The resistance mechanism that describes the function of β-lactamase is the ___ .", "normal_format": "Which of the following resistance mechanisms describes the function of β-lactamase?", "question_choices": [ "efflux pump", "target mimicry", "drug inactivation", "target overproduction" ], "question_id": "fs-id1167661397905", "question_text": "Which of the following resistance mechanisms describes the function of β-lactamase?" }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 0, "ans_text": "A" }, "bloom": null, "hl_context": "From a clinical perspective , our greatest concerns are multidrug-resistant microbes ( MDRs ) and cross resistance . MDRs are colloquially known as “ superbugs ” and carry one or more resistance mechanism ( s ) , making them resistant to multiple antimicrobials . <hl> In cross-resistance , a single resistance mechanism confers resistance to multiple antimicrobial drugs . <hl> <hl> For example , having an efflux pump that can export multiple antimicrobial drugs is a common way for microbes to be resistant to multiple drugs by using a single resistance mechanism . <hl> In recent years , several clinically important superbugs have emerged , and the CDC reports that superbugs are responsible for more than 2 million infections in the US annually , resulting in at least 23,000 fatalities . 19 Several of the superbugs discussed in the following sections have been dubbed the ESKAPE pathogens . This acronym refers to the names of the pathogens ( Enterococcus faecium , Staphylococcus aureus , Klebsiella pneumoniae , Acinetobacter baumannii , Pseudomonas aeruginosa and Enterobacter spp . ) but it is also fitting in that these pathogens are able to “ escape ” many conventional forms of antimicrobial therapy . As such , infections by ESKAPE pathogens can be difficult to treat and they cause a large number of nosocomial infections . 19 Centers for Disease Control and Prevention . “ Antibiotic / Antimicrobial Resistance . ” http://www.cdc.gov/drugresistance/index.html . Accessed June 2 , 2016 .", "hl_sentences": "In cross-resistance , a single resistance mechanism confers resistance to multiple antimicrobial drugs . For example , having an efflux pump that can export multiple antimicrobial drugs is a common way for microbes to be resistant to multiple drugs by using a single resistance mechanism .", "question": { "cloze_format": "The resistance mechanism that is commonly effective against a wide range of antimicrobials in multiple classes is the ___.", "normal_format": "Which of the following resistance mechanisms is commonly effective against a wide range of antimicrobials in multiple classes?", "question_choices": [ "efflux pump", "target mimicry", "target modification", "target overproduction" ], "question_id": "fs-id1167661424151", "question_text": "Which of the following resistance mechanisms is commonly effective against a wide range of antimicrobials in multiple classes?" }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 3, "ans_text": "D" }, "bloom": null, "hl_context": "Microbes may develop resistance mechanisms that involve inhibiting the accumulation of an antimicrobial drug , which then prevents the drug from reaching its cellular target . This strategy is common among gram-negative pathogens and can involve changes in outer membrane lipid composition , porin channel selectivity , and / or porin channel concentrations . For example , a common mechanism of carbapenem resistance among Pseudomonas aeruginosa is to decrease the amount of its OprD porin , which is the primary portal of entry for carbapenems through the outer membrane of this pathogen . <hl> Additionally , many gram-positive and gram-negative pathogenic bacteria produce efflux pump s that actively transport an antimicrobial drug out of the cell and prevent the accumulation of drug to a level that would be antibacterial . <hl> <hl> For example , resistance to β-lactams , tetracyclines , and fluoroquinolones commonly occurs through active efflux out of the cell , and it is rather common for a single efflux pump to have the ability to translocate multiple types of antimicrobials . <hl>", "hl_sentences": "Additionally , many gram-positive and gram-negative pathogenic bacteria produce efflux pump s that actively transport an antimicrobial drug out of the cell and prevent the accumulation of drug to a level that would be antibacterial . For example , resistance to β-lactams , tetracyclines , and fluoroquinolones commonly occurs through active efflux out of the cell , and it is rather common for a single efflux pump to have the ability to translocate multiple types of antimicrobials .", "question": { "cloze_format": "The resistance mechanism that is the most nonspecific to a particular class of antimicrobials is the ___.", "normal_format": "Which of the following resistance mechanisms is the most nonspecific to a particular class of antimicrobials?", "question_choices": [ "drug modification", "target mimicry", "target modification", "efflux pump" ], "question_id": "fs-id1167661737849", "question_text": "Which of the following resistance mechanisms is the most nonspecific to a particular class of antimicrobials?" }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 0, "ans_text": "A" }, "bloom": null, "hl_context": "<hl> The occurrence of carbapenem-resistant Enterobacteriaceae ( CRE ) and carbapenem resistance among other gram-negative bacteria ( e . g . , P . aeruginosa , Acinetobacter baumannii , Stenotrophomonas maltophila ) is a growing health-care concern . <hl> These pathogens develop resistance to carbapenems through a variety of mechanisms , including production of carbapenemases ( broad-spectrum β-lactamases that inactivate all β-lactams , including carbapenems ) , active efflux of carbapenems out of the cell , and / or prevention of carbapenem entry through porin channels . Similar to concerns with ESBLs , carbapenem-resistant , gram-negative pathogens are usually resistant to multiple classes of antibacterials , and some have even developed pan-resistance ( resistance to all available antibacterials ) . Infections with carbapenem-resistant , gram-negative pathogens commonly occur in health-care settings through interaction with contaminated individuals or medical devices , or as a result of surgery . <hl> Gram-negative pathogens that produce extended-spectrum β-lactamases ( ESBLs ) show resistance well beyond just penicillins . <hl> The spectrum of β-lactams inactivated by ESBLs provides for resistance to all penicillins , cephalosporins , monobactams , and the β-lactamase-inhibitor combinations , but not the carbapenems . An even greater concern is that the genes encoding for ESBLs are usually found on mobile plasmids that also contain genes for resistance to other drug classes ( e . g . , fluoroquinolones , aminoglycosides , tetracyclines ) , and may be readily spread to other bacteria by horizontal gene transfer . <hl> These multidrug-resistant bacteria are members of the intestinal microbiota of some individuals , but they are also important causes of opportunistic infections in hospitalized patients , from whom they can be spread to other people . <hl> <hl> Vancomycin is only effective against gram-positive organisms , and it is used to treat wound infections , septic infections , endocarditis , and meningitis that are caused by pathogens resistant to other antibiotics . <hl> It is considered one of the last lines of defense against such resistant infections , including MRSA . With the rise of antibiotic resistance in the 1970s and 1980s , vancomycin use increased , and it is not surprising that we saw the emergence and spread of vancomycin-resistant enterococci ( VRE ) , vancomycin-resistant S . aureus ( VRSA ) , and vancomycin-intermediate S . aureus ( VISA ) . The mechanism of vancomycin resistance among enterococci is target modification involving a structural change to the peptide component of the peptidoglycan subunits , preventing vancomycin from binding . These strains are typically spread among patients in clinical settings by contact with health-care workers and contaminated surfaces and medical equipment . Methicillin , a semisynthetic penicillin , was designed to resist inactivation by β-lactamases . Unfortunately , soon after the introduction of methicillin to clinical practice , methicillin-resistant strains of S . aureus appeared and started to spread . The mechanism of resistance , acquisition of a new low-affinity PBP , provided S . aureus with resistance to all available β-lactams . <hl> Strains of methicillin-resistant S . aureus ( MRSA ) are widespread opportunistic pathogens and a particular concern for skin and other wound infections , but may also cause pneumonia and septicemia . <hl> <hl> Although originally a problem in health-care settings ( hospital-acquired MRSA [ HA-MRSA ] ) , MRSA infections are now also acquired through contact with contaminated members of the general public , called community-associated MRSA ( CA-MRSA ) . <hl> Approximately one-third of the population carries S . aureus as a member of their normal nasal microbiota without illness , and about 6 % of these strains are methicillin resistant . 20 21 20 A . S . Kalokhe et al . “ Multidrug-Resistant Tuberculosis Drug Susceptibility and Molecular Diagnostic Testing : A Review of the Literature . American Journal of the Medical Sciences 345 no . 2 ( 2013 ): 143 – 148 . 21 Centers for Disease Control and Prevention . “ Methicillin-Resistant Staphylococcus aureus ( MRSA ): General Information About MRSA in the Community . ” http://www.cdc.gov/mrsa/community/index.html . Accessed June 2 , 2016", "hl_sentences": "The occurrence of carbapenem-resistant Enterobacteriaceae ( CRE ) and carbapenem resistance among other gram-negative bacteria ( e . g . , P . aeruginosa , Acinetobacter baumannii , Stenotrophomonas maltophila ) is a growing health-care concern . Gram-negative pathogens that produce extended-spectrum β-lactamases ( ESBLs ) show resistance well beyond just penicillins . These multidrug-resistant bacteria are members of the intestinal microbiota of some individuals , but they are also important causes of opportunistic infections in hospitalized patients , from whom they can be spread to other people . Vancomycin is only effective against gram-positive organisms , and it is used to treat wound infections , septic infections , endocarditis , and meningitis that are caused by pathogens resistant to other antibiotics . Strains of methicillin-resistant S . aureus ( MRSA ) are widespread opportunistic pathogens and a particular concern for skin and other wound infections , but may also cause pneumonia and septicemia . Although originally a problem in health-care settings ( hospital-acquired MRSA [ HA-MRSA ] ) , MRSA infections are now also acquired through contact with contaminated members of the general public , called community-associated MRSA ( CA-MRSA ) .", "question": { "cloze_format": "The type of drug-resistant bacteria that does not typically persist in individuals as a member of their intestinal microbiota is ___.", "normal_format": "Which of the following types of drug-resistant bacteria do not typically persist in individuals as a member of their intestinal microbiota?", "question_choices": [ "MRSA", "VRE", "CRE", "ESBL-producing bacteria" ], "question_id": "fs-id1167663931670", "question_text": "Which of the following types of drug-resistant bacteria do not typically persist in individuals as a member of their intestinal microbiota?" }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 0, "ans_text": "A" }, "bloom": null, "hl_context": "<hl> The Kirby-Bauer disk diffusion test has long been used as a starting point for determining the susceptibility of specific microbes to various antimicrobial drugs . <hl> The Kirby-Bauer assay starts with a Mueller-Hinton agar plate on which a confluent lawn is inoculated with a patient ’ s isolated bacterial pathogen . Filter paper disks impregnated with known amounts of antibacterial drugs to be tested are then placed on the agar plate . As the bacterial inoculum grows , antibiotic diffuses from the circular disk into the agar and interacts with the growing bacteria . Antibacterial activity is observed as a clear circular zone of inhibition around the drug-impregnated disk , similar to the disk-diffusion assay depicted in Figure 13.31 . <hl> The diameter of the zone of inhibition , measured in millimeters and compared to a standardized chart , determines the susceptibility or resistance of the bacterial pathogen to the drug . <hl>", "hl_sentences": "The Kirby-Bauer disk diffusion test has long been used as a starting point for determining the susceptibility of specific microbes to various antimicrobial drugs . The diameter of the zone of inhibition , measured in millimeters and compared to a standardized chart , determines the susceptibility or resistance of the bacterial pathogen to the drug .", "question": { "cloze_format": "In the Kirby-Bauer disk diffusion test, the _______ of the zone of inhibition is measured and used for interpretation.", "normal_format": "In the Kirby-Bauer disk diffusion test, what of the zone of inhibition is measured and used for interpretation?", "question_choices": [ "diameter", "microbial population", "circumference", "depth" ], "question_id": "fs-id1167659011346", "question_text": "In the Kirby-Bauer disk diffusion test, the _______ of the zone of inhibition is measured and used for interpretation." }, "references_are_paraphrase": 0 }, { "answer": { "ans_choice": 2, "ans_text": "C" }, "bloom": null, "hl_context": "<hl> As discussed , the limitations of the Kirby-Bauer disk diffusion test do not allow for a direct comparison of antibacterial potencies to guide selection of the best therapeutic choice . <hl> <hl> However , antibacterial dilution tests can be used to determine a particular drug ’ s minimal inhibitory concentration ( MIC ) , the lowest concentration of drug that inhibits visible bacterial growth , and minimal bactericidal concentration ( MBC ) , the lowest drug concentration that kills ≥ 99.9 % of the starting inoculum . <hl> Determining these concentrations helps identify the correct drug for a particular pathogen . For the macrobroth dilution assay , a dilution series of the drug in broth is made in test tubes and the same number of cells of a test bacterial strain is added to each tube ( Figure 14.19 ) . The MIC is determined by examining the tubes to find the lowest drug concentration that inhibits visible growth ; this is observed as turbidity ( cloudiness ) in the broth . Tubes with no visible growth are then inoculated onto agar media without antibiotic to determine the MBC . Generally , serum levels of an antibacterial should be at least three to five times above the MIC for treatment of an infection .", "hl_sentences": "As discussed , the limitations of the Kirby-Bauer disk diffusion test do not allow for a direct comparison of antibacterial potencies to guide selection of the best therapeutic choice . However , antibacterial dilution tests can be used to determine a particular drug ’ s minimal inhibitory concentration ( MIC ) , the lowest concentration of drug that inhibits visible bacterial growth , and minimal bactericidal concentration ( MBC ) , the lowest drug concentration that kills ≥ 99.9 % of the starting inoculum .", "question": { "cloze_format": "The technique that cannot be used to determine the minimum inhibitory concentration of an antimicrobial drug against a particular microbe is the ___.", "normal_format": "Which of the following techniques cannot be used to determine the minimum inhibitory concentration of an antimicrobial drug against a particular microbe?", "question_choices": [ "Etest", "microbroth dilution test", "Kirby-Bauer disk diffusion test", "macrobroth dilution test" ], "question_id": "fs-id1167663964408", "question_text": "Which of the following techniques cannot be used to determine the minimum inhibitory concentration of an antimicrobial drug against a particular microbe?" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 3, "ans_text": "D" }, "bloom": null, "hl_context": "Recently , studies have shown that antibiograms are useful tools in the decision-making process of selecting appropriate empiric therapy . <hl> An antibiogram is a compilation of local antibiotic susceptibility data broken down by bacterial pathogen . <hl> In a November 2014 study published in the journal Infection Control and Hospital Epidemiology , researchers determined that 85 % of the prescriptions ordered in skilled nursing facilities were decided upon empirically , but only 35 % of those prescriptions were deemed appropriate when compared with the eventual pathogen identification and susceptibility profile obtained from the clinical laboratory . However , in one nursing facility where use of antibiograms was implemented to direct selection of empiric therapy , appropriateness of empiric therapy increased from 32 % before antibiogram implementation to 45 % after implementation of antibiograms . 24 Although these data are preliminary , they do suggest that health-care facilities can reduce the number of inappropriate prescriptions by using antibiograms to select empiric therapy , thus benefiting patients and minimizing opportunities for antimicrobial resistance to develop . 24 J . P . Furuno et al . “ Using Antibiograms to Improve Antibiotic Prescribing in Skilled Nursing Facilities . ” Infection Control and Hospital Epidemiology 35 no . Suppl S3 ( 2014 ): S56 – 61 .", "hl_sentences": "An antibiogram is a compilation of local antibiotic susceptibility data broken down by bacterial pathogen .", "question": { "cloze_format": "The utility of an antibiogram is that it shows antimicrobial susceptibility trends ___ .", "normal_format": "How the utility of an antibiogram shows antimicrobial susceptibility trends?", "question_choices": [ "over a large geographic area.", "for an individual patient.", "in research laboratory strains.", "in a localized population." ], "question_id": "fs-id1167661481139", "question_text": "The utility of an antibiogram is that it shows antimicrobial susceptibility trends" }, "references_are_paraphrase": null }, { "answer": { "ans_choice": 3, "ans_text": "D" }, "bloom": null, "hl_context": "<hl> Although soils have been widely examined , other environmental niches have not been tested as fully . <hl> Since 70 % of the earth is covered with water , marine environments could be mined more fully for the presence of antimicrobial-producing microbes . <hl> In addition , researchers are using combinatorial chemistry , a method for making a very large number of related compounds from simple precursors , and testing them for antimicrobial activity . <hl> An additional strategy that needs to be explored further is the development of compounds that inhibit resistance mechanisms and restore the activity of older drugs , such as the strategy described earlier for β-lactamase inhibitors like clavulanic acid . Finally , developing inhibitors of virulence factor production and function could be a very important avenue . Although this strategy would not be directly antibacterial , drugs that slow the progression of an infection could provide an advantage for the immune system and could be used successfully in combination with antimicrobial drugs .", "hl_sentences": "Although soils have been widely examined , other environmental niches have not been tested as fully . In addition , researchers are using combinatorial chemistry , a method for making a very large number of related compounds from simple precursors , and testing them for antimicrobial activity .", "question": { "cloze_format": "___ has/have yielded compounds with the most antimicrobial activity.", "normal_format": "Which of the following has yielded compounds with the most antimicrobial activity?", "question_choices": [ "water", "air", "volcanoes", "soil" ], "question_id": "fs-id1167661463241", "question_text": "Which of the following has yielded compounds with the most antimicrobial activity?" }, "references_are_paraphrase": null } ]
14
14.1 History of Chemotherapy and Antimicrobial Discovery Learning Objectives Compare and contrast natural, semisynthetic, and synthetic antimicrobial drugs Describe the chemotherapeutic approaches of ancient societies Describe the historically important individuals and events that led to the development of antimicrobial drugs Clinical Focus Part 1 Marisa, a 52-year-old woman, was suffering from severe abdominal pain, swollen lymph nodes, fatigue, and a fever. She had just returned home from visiting extended family in her native country of Cambodia. While abroad, she received medical care in neighboring Vietnam for a compressed spinal cord. She still had discomfort when leaving Cambodia, but the pain increased as her trip home continued and her husband drove her straight from the airport to the emergency room. Her doctor considers whether Marisa could be suffering from appendicitis, a urinary tract infection (UTI), or pelvic inflammatory disease (PID). However, each of those conditions is typically preceded or accompanied by additional symptoms. He considers the treatment she received in Vietnam for her compressed spinal cord, but abdominal pain is not usually associated with spinal cord compression. He examines her health history further. What type of infection or other condition may be responsible? What type of lab tests might the doctor order? Jump to the next Clinical Focus box. Most people associate the term chemotherapy with treatments for cancer. However, chemotherapy is actually a broader term that refers to any use of chemicals or drugs to treat disease. Chemotherapy may involve drugs that target cancerous cells or tissues, or it may involve antimicrobial drugs that target infectious microorganisms. Antimicrobial drugs typically work by destroying or interfering with microbial structures and enzymes, either killing microbial cells or inhibiting of their growth. But before we examine how these drugs work, we will briefly explore the history of humans’ use of antimicrobials for the purpose of chemotherapy. Use of Antimicrobials in Ancient Societies Although the discovery of antimicrobials and their subsequent widespread use is commonly associated with modern medicine, there is evidence that humans have been exposed to antimicrobial compounds for millennia. Chemical analyses of the skeletal remains of people from Nubia 2 (now found in present-day Sudan) dating from between 350 and 550 AD have shown residue of the antimicrobial agent tetracycline in high enough quantities to suggest the purposeful fermentation of tetracycline-producing Streptomyces during the beer-making process. The resulting beer , which was thick and gruel-like, was used to treat a variety of ailments in both adults and children, including gum disease and wounds. The antimicrobial properties of certain plants may also have been recognized by various cultures around the world, including Indian and Chinese herbalists ( Figure 14.2 ) who have long used plants for a wide variety of medical purposes. Healers of many cultures understood the antimicrobial properties of fungi and their use of moldy bread or other mold-containing products to treat wounds has been well documented for centuries. 3 Today, while about 80% of the world’s population still relies on plant-derived medicines, 4 scientists are now discovering the active compounds conferring the medicinal benefits contained in many of these traditionally used plants. 2 M.L. Nelson et al. “Brief Communication: Mass Spectroscopic Characterization of Tetracycline in the Skeletal Remains of an Ancient Population from Sudanese Nubia 350–550 CE.” American Journal of Physical Anthropology 143 no. 1 (2010):151–154. 3 M. Wainwright. “Moulds in Ancient and More Recent Medicine.” Mycologist 3 no. 1 (1989):21–23. 4 S. Verma, S.P. Singh. “Current and Future Status of Herbal Medicines.” Veterinary World 1 no. 11 (2008):347–350. Check Your Understanding Give examples of how antimicrobials were used in ancient societies. The First Antimicrobial Drugs Societies relied on traditional medicine for thousands of years; however, the first half of the 20th century brought an era of strategic drug discovery. In the early 1900s, the German physician and scientist Paul Ehrlich (1854–1915) set out to discover or synthesize chemical compounds capable of killing infectious microbes without harming the patient. In 1909, after screening more than 600 arsenic-containing compounds, Ehrlich’s assistant Sahachiro Hata (1873–1938) found one such “magic bullet.” Compound 606 targeted the bacterium Treponema pallidum , the causative agent of syphilis. Compound 606 was found to successfully cure syphilis in rabbits and soon after was marketed under the name Salvarsan as a remedy for the disease in humans ( Figure 14.3 ). Ehrlich’s innovative approach of systematically screening a wide variety of compounds remains a common strategy for the discovery of new antimicrobial agents even today. A few decades later, German scientists Josef Klarer , Fritz Mietzsch , and Gerhard Domagk discovered the antibacterial activity of a synthetic dye, prontosil , that could treat streptococcal and staphylococcal infections in mice. Domagk’s own daughter was one of the first human recipients of the drug, which completely cured her of a severe streptococcal infection that had resulted from a poke with an embroidery needle. Gerhard Domagk (1895–1964) was awarded the Nobel Prize in Medicine in 1939 for his work with prontosil and sulfanilamide , the active breakdown product of prontosil in the body. Sulfanilamide, the first synthetic antimicrobial created, served as the foundation for the chemical development of a family of sulfa drugs. A synthetic antimicrobial is a drug that is developed from a chemical not found in nature. The success of the sulfa drugs led to the discovery and production of additional important classes of synthetic antimicrobials, including the quinolines and oxazolidinones . A few years before the discovery of prontosil, scientist Alexander Fleming (1881–1955) made his own accidental discovery that turned out to be monumental. In 1928, Fleming returned from holiday and examined some old plates of staphylococci in his research laboratory at St. Mary’s Hospital in London. He observed that contaminating mold growth (subsequently identified as a strain of Penicillium notatum ) inhibited staphylococcal growth on one plate. Fleming, therefore, is credited with the discovery of penicillin , the first natural antibiotic , ( Figure 14.4 ). Further experimentation showed that penicillin from the mold was antibacterial against streptococci, meningococci, and Corynebacterium diphtheriae , the causative agent of diphtheria. Fleming and his colleagues were credited with discovering and identifying penicillin, but its isolation and mass production were accomplished by a team of researchers at Oxford University under the direction of Howard Florey (1898–1968) and Ernst Chain (1906–1979) ( Figure 14.4 ). In 1940, the research team purified penicillin and reported its success as an antimicrobial agent against streptococcal infections in mice. Their subsequent work with human subjects also showed penicillin to be very effective. Because of their important work, Fleming, Florey, and Chain were awarded the Nobel Prize in Physiology and Medicine in 1945. In the early 1940s, scientist Dorothy Hodgkin (1910–1994), who studied crystallography at Oxford University, used X-rays to analyze the structure of a variety of natural products. In 1946, she determined the structure of penicillin, for which she was awarded the Nobel Prize in Chemistry in 1964. Once the structure was understood, scientists could modify it to produce a variety of semisynthetic penicillins. A semisynthetic antimicrobial is a chemically modified derivative of a natural antibiotic. The chemical modifications are generally designed to increase the range of bacteria targeted, increase stability, decrease toxicity, or confer other properties beneficial for treating infections. Penicillin is only one example of a natural antibiotic. Also in the 1940s, Selman Waksman (1888–1973) ( Figure 14.5 ), a prominent soil microbiologist at Rutgers University, led a research team that discovered several antimicrobials, including actinomycin , streptomycin , and neomycin . The discoveries of these antimicrobials stemmed from Waksman’s study of fungi and the Actinobacteria , including soil bacteria in the genus Streptomyces , known for their natural production of a wide variety of antimicrobials. His work earned him the Nobel Prize in Physiology and Medicine in 1952. The actinomycetes are the source of more than half of all natural antibiotics 5 and continue to serve as an excellent reservoir for the discovery of novel antimicrobial agents. Some researchers argue that we have not yet come close to tapping the full antimicrobial potential of this group. 6 5 J. Berdy. “Bioactive Microbial Metabolites.” The Journal of Antibiotics 58 no. 1 (2005):1–26. 6 M. Baltz. “Antimicrobials from Actinomycetes: Back to the Future.” Microbe 2 no. 3 (2007):125–131. Check Your Understanding Why is the soil a reservoir for antimicrobial resistance genes? 14.2 Fundamentals of Antimicrobial Chemotherapy Learning Objectives Contrast bacteriostatic versus bactericidal antibacterial activities Contrast broad-spectrum drugs versus narrow-spectrum drugs Explain the significance of superinfections Discuss the significance of dosage and the route of administration of a drug Identify factors and variables that can influence the side effects of a drug Describe the significance of positive and negative interactions between drugs Several factors are important in choosing the most appropriate antimicrobial drug therapy, including bacteriostatic versus bactericidal mechanisms, spectrum of activity , dosage and route of administration , the potential for side effects , and the potential interactions between drugs. The following discussion will focus primarily on antibacterial drugs , but the concepts translate to other antimicrobial classes. Bacteriostatic Versus Bactericidal Antibacterial drugs can be either bacteriostatic or bactericidal in their interactions with target bacteria. Bacteriostatic drugs cause a reversible inhibition of growth, with bacterial growth restarting after elimination of the drug. By contrast, bactericidal drugs kill their target bacteria. The decision of whether to use a bacteriostatic or bactericidal drugs depends on the type of infection and the immune status of the patient. In a patient with strong immune defenses, bacteriostatic and bactericidal drugs can be effective in achieving clinical cure. However, when a patient is immunocompromised, a bactericidal drug is essential for the successful treatment of infections. Regardless of the immune status of the patient, life-threatening infections such as acute endocarditis require the use of a bactericidal drug. Spectrum of Activity The spectrum of activity of an antibacterial drug relates to diversity of targeted bacteria. A narrow-spectrum antimicrobial targets only specific subsets of bacterial pathogens. For example, some narrow-spectrum drugs only target gram-positive bacteria , whereas others target only gram-negative bacteria . If the pathogen causing an infection has been identified, it is best to use a narrow-spectrum antimicrobial and minimize collateral damage to the normal microbiota. A broad-spectrum antimicrobial targets a wide variety of bacterial pathogens, including both gram-positive and gram-negative species, and is frequently used as empiric therapy to cover a wide range of potential pathogens while waiting on the laboratory identification of the infecting pathogen. Broad-spectrum antimicrobials are also used for polymicrobic infections (mixed infection with multiple bacterial species), or as prophylactic prevention of infections with surgery/invasive procedures. Finally, broad-spectrum antimicrobials may be selected to treat an infection when a narrow-spectrum drug fails because of development of drug resistance by the target pathogen. The risk associated with using broad-spectrum antimicrobials is that they will also target a broad spectrum of the normal microbiota, increasing the risk of a superinfection , a secondary infection in a patient having a preexisting infection. A superinfection develops when the antibacterial intended for the preexisting infection kills the protective microbiota , allowing another pathogen resistant to the antibacterial to proliferate and cause a secondary infection ( Figure 14.6 ). Common examples of superinfections that develop as a result of antimicrobial usage include yeast infections ( candidiasis ) and pseudomembranous colitis caused by Clostridium difficile , which can be fatal. Check Your Understanding What is a superinfection and how does one arise? Dosage and Route of Administration The amount of medication given during a certain time interval is the dosage , and it must be determined carefully to ensure that optimum therapeutic drug levels are achieved at the site of infection without causing significant toxicity ( side effects ) to the patient. Each drug class is associated with a variety of potential side effects, and some of these are described for specific drugs later in this chapter. Despite best efforts to optimize dosing, allergic reactions and other potentially serious side effects do occur. Therefore, the goal is to select the optimum dosage that will minimize the risk of side effects while still achieving clinical cure, and there are important factors to consider when selecting the best dose and dosage interval. For example, in children, dose is based upon the patient’s mass. However, the same is not true for adults and children 12 years of age and older, for which there is typically a single standard dose regardless of the patient’s mass. With the great variability in adult body mass, some experts have argued that mass should be considered for all patients when determining appropriate dosage. 7 An additional consideration is how drugs are metabolized and eliminated from the body. In general, patients with a history of liver or kidney dysfunction may experience reduced drug metabolism or clearance from the body, resulting in increased drug levels that may lead to toxicity and make them more prone to side effects. 7 M.E. Falagas, D.E. Karageorgopoulos. “Adjustment of Dosing of Antimicrobial Agents for Bodyweight in Adults.” The Lancet 375 no. 9710 (2010):248–251. There are also some factors specific to the drugs themselves that influence appropriate dose and time interval between doses. For example, the half-life , or rate at which 50% of a drug is eliminated from the plasma, can vary significantly between drugs. Some drugs have a short half-life of only 1 hour and must be given multiple times a day, whereas other drugs have half-lives exceeding 12 hours and can be given as a single dose every 24 hours. Although a longer half-life can be considered an advantage for an antibacterial when it comes to convenient dosing intervals, the longer half-life can also be a concern for a drug that has serious side effects because drug levels may remain toxic for a longer time. Last, some drugs are dose dependent, meaning they are more effective when administered in large doses to provide high levels for a short time at the site of infection. Others are time dependent, meaning they are more effective when lower optimum levels are maintained over a longer period of time. The route of administration , the method used to introduce a drug into the body, is also an important consideration for drug therapy. Drugs that can be administered orally are generally preferred because patients can more conveniently take these drugs at home. However, some drugs are not absorbed easily from the gastrointestinal (GI) tract into the bloodstream. These drugs are often useful for treating diseases of the intestinal tract, such as tapeworms treated with niclosamide , or for decontaminating the bowel, as with colistin . Some drugs that are not absorbed easily, such as bacitracin , polymyxin , and several antifungals, are available as topical preparations for treatment of superficial skin infections. Sometimes, patients may not initially be able to take oral medications because of their illness (e.g., vomiting, intubation for respirator). When this occurs, and when a chosen drug is not absorbed in the GI tract, administration of the drug by a parenteral route (intravenous or intramuscular injection) is preferred and typically is performed in health-care settings. For most drugs, the plasma levels achieved by intravenous administration is substantially higher than levels achieved by oral or intramuscular administration, and this can also be an important consideration when choosing the route of administration for treating an infection ( Figure 14.7 ). Check Your Understanding List five factors to consider when determining the dosage of a drug. Name some typical side effects associated with drugs and identify some factors that might contribute to these side effects. Drug Interactions For the optimum treatment of some infections, two antibacterial drugs may be administered together to provide a synergistic interaction that is better than the efficacy of either drug alone. A classic example of synergistic combinations is trimethoprim and sulfamethoxazole ( Bactrim ). Individually, these two drugs provide only bacteriostatic inhibition of bacterial growth, but combined, the drugs are bactericidal . Whereas synergistic drug interactions provide a benefit to the patient, antagonistic interactions produce harmful effects. Antagonism can occur between two antimicrobials or between antimicrobials and nonantimicrobials being used to treat other conditions. The effects vary depending on the drugs involved, but antagonistic interactions may cause loss of drug activity, decreased therapeutic levels due to increased metabolism and elimination, or increased potential for toxicity due to decreased metabolism and elimination. As an example, some antibacterials are absorbed most effectively from the acidic environment of the stomach. If a patient takes antacids, however, this increases the pH of the stomach and negatively impacts the absorption of these antimicrobials, decreasing their effectiveness in treating an infection. Studies have also shown an association between use of some antimicrobials and failure of oral contraceptives. 8 8 B.D. Dickinson et al. “Drug Interactions between Oral Contraceptives and Antibiotics.” Obstetrics & Gynecology 98, no. 5 (2001):853–860. Check Your Understanding Explain the difference between synergistic and antagonistic drug interactions. Eye on Ethics Resistance Police In the United States and many other countries, most antimicrobial drugs are self-administered by patients at home. Unfortunately, many patients stop taking antimicrobials once their symptoms dissipate and they feel better. If a 10-day course of treatment is prescribed, many patients only take the drug for 5 or 6 days, unaware of the negative consequences of not completing the full course of treatment. A shorter course of treatment not only fails to kill the target organisms to expected levels, it also selects for drug-resistant variants within the target population and within the patient’s microbiota. Patients’ nonadherence especially amplifies drug resistance when the recommended course of treatment is long. Treatment for tuberculosis (TB) is a case in point, with the recommended treatment lasting from 6 months to a year. The CDC estimates that about one-third of the world’s population is infected with TB, most living in underdeveloped or underserved regions where antimicrobial drugs are available over the counter. In such countries, there may be even lower rates of adherence than in developed areas. Nonadherence leads to antibiotic resistance and more difficulty in controlling pathogens. As a direct result, the emergence of multidrug-resistant and extensively drug-resistant strains of TB is becoming a huge problem. Overprescription of antimicrobials also contributes to antibiotic resistance. Patients often demand antibiotics for diseases that do not require them, like viral colds and ear infections. Pharmaceutical companies aggressively market drugs to physicians and clinics, making it easy for them to give free samples to patients, and some pharmacies even offer certain antibiotics free to low-income patients with a prescription. In recent years, various initiatives have aimed to educate parents and clinicians about the judicious use of antibiotics. However, a recent study showed that, between 2000 and 2013, the parental expectation for antimicrobial prescriptions for children actually increased ( Figure 14.8 ). One possible solution is a regimen called directly observed therapy (DOT) , which involves the supervised administration of medications to patients. Patients are either required to visit a health-care facility to receive their medications, or health-care providers must administer medication in patients’ homes or another designated location. DOT has been implemented in many cases for the treatment of TB and has been shown to be effective; indeed, DOT is an integral part of WHO’s global strategy for eradicating TB. 9 , 10 But is this a practical strategy for all antibiotics? Would patients taking penicillin, for example, be more or less likely to adhere to the full course of treatment if they had to travel to a health-care facility for each dose? And who would pay for the increased cost associated with DOT? When it comes to overprescription, should someone be policing physicians or drug companies to enforce best practices? What group should assume this responsibility, and what penalties would be effective in discouraging overprescription? 9 Centers for Disease Control and Prevention. “Tuberculosis (TB).” http://www.cdc.gov/tb/education/ssmodules/module9/ss9reading2.htm. Accessed June 2, 2016. 10 World Health Organization. “Tuberculosis (TB): The Five Elements of DOTS.” http://www.who.int/tb/dots/whatisdots/en/. Accessed June 2, 2016. 14.3 Mechanisms of Antibacterial Drugs Learning Objective Describe the mechanisms of action associated with drugs that inhibit cell wall biosynthesis, protein synthesis, membrane function, nucleic acid synthesis, and metabolic pathways An important quality for an antimicrobial drug is selective toxicity , meaning that it selectively kills or inhibits the growth of microbial targets while causing minimal or no harm to the host. Most antimicrobial drugs currently in clinical use are antibacterial because the prokaryotic cell provides a greater variety of unique targets for selective toxicity, in comparison to fungi, parasites, and viruses. Each class of antibacterial drugs has a unique mode of action (the way in which a drug affects microbes at the cellular level), and these are summarized in Figure 14.9 and Table 14.1 . Common Antibacterial Drugs by Mode of Action Mode of Action Target Drug Class Inhibit cell wall biosynthesis Penicillin-binding proteins β-lactams: penicillins, cephalosporins, monobactams, carbapenems Peptidoglycan subunits Glycopeptides Peptidoglycan subunit transport Bacitracin Inhibit biosynthesis of proteins 30S ribosomal subunit Aminoglycosides, tetracyclines 50S ribosomal subunit Macrolides, lincosamides, chloramphenicol, oxazolidinones Disrupt membranes Lipopolysaccharide, inner and outer membranes Polymyxin B, colistin, daptomycin Inhibit nucleic acid synthesis RNA Rifamycin DNA Fluoroquinolones Antimetabolites Folic acid synthesis enzyme Sulfonamides, trimethoprim Mycolic acid synthesis enzyme Isonicotinic acid hydrazide Mycobacterial adenosine triphosphate (ATP) synthase inhibitor Mycobacterial ATP synthase Diarylquinoline Table 14.1 Inhibitors of Cell Wall Biosynthesis Several different classes of antibacterials block steps in the biosynthesis of peptidoglycan , making cells more susceptible to osmotic lysis ( Table 14.2 ). Therefore, antibacterials that target cell wall biosynthesis are bactericidal in their action. Because human cells do not make peptidoglycan, this mode of action is an excellent example of selective toxicity. Penicillin, the first antibiotic discovered, is one of several antibacterials within a class called β-lactams . This group of compounds includes the penicillins , cephalosporins , monobactams , and carbapenems , and is characterized by the presence of a β-lactam ring found within the central structure of the drug molecule ( Figure 14.10 ). The β-lactam antibacterials block the crosslinking of peptide chains during the biosynthesis of new peptidoglycan in the bacterial cell wall. They are able to block this process because the β-lactam structure is similar to the structure of the peptidoglycan subunit component that is recognized by the crosslinking transpeptidase enzyme, also known as a penicillin-binding protein (PBP) . Although the β-lactam ring must remain unchanged for these drugs to retain their antibacterial activity, strategic chemical changes to the R groups have allowed for development of a wide variety of semisynthetic β-lactam drugs with increased potency , expanded spectrum of activity , and longer half-lives for better dosing, among other characteristics. Penicillin G and penicillin V are natural antibiotics from fungi and are primarily active against gram-positive bacterial pathogens, and a few gram-negative bacterial pathogens such as Pasteurella multocida . Figure 14.10 summarizes the semisynthetic development of some of the penicillins. Adding an amino group (-NH 2 ) to penicillin G created the aminopenicillins (i.e., ampicillin and amoxicillin ) that have increased spectrum of activity against more gram-negative pathogens. Furthermore, the addition of a hydroxyl group (-OH) to amoxicillin increased acid stability, which allows for improved oral absorption. Methicillin is a semisynthetic penicillin that was developed to address the spread of enzymes ( penicillinases ) that were inactivating the other penicillins. Changing the R group of penicillin G to the more bulky dimethoxyphenyl group provided protection of the β-lactam ring from enzymatic destruction by penicillinases, giving us the first penicillinase-resistant penicillin. Similar to the penicillins, cephalosporins contain a β-lactam ring ( Figure 14.10 ) and block the transpeptidase activity of penicillin-binding proteins. However, the β-lactam ring of cephalosporins is fused to a six-member ring, rather than the five-member ring found in penicillins. This chemical difference provides cephalosporins with an increased resistance to enzymatic inactivation by β-lactamases . The drug cephalosporin C was originally isolated from the fungus Cephalosporium acremonium in the 1950s and has a similar spectrum of activity to that of penicillin against gram-positive bacteria but is active against more gram-negative bacteria than penicillin . Another important structural difference is that cephalosporin C possesses two R groups, compared with just one R group for penicillin, and this provides for greater diversity in chemical alterations and development of semisynthetic cephalosporins. The family of semisynthetic cephalosporins is much larger than the penicillins, and these drugs have been classified into generations based primarily on their spectrum of activity, increasing in spectrum from the narrow-spectrum, first-generation cephalosporins to the broad-spectrum, fourth-generation cephalosporins. A new fifth-generation cephalosporin has been developed that is active against methicillin-resistant Staphylococcus aureus (MRSA) . The carbapenems and monobactams also have a β-lactam ring as part of their core structure, and they inhibit the transpeptidase activity of penicillin-binding proteins. The only monobactam used clinically is aztreonam . It is a narrow-spectrum antibacterial with activity only against gram-negative bacteria. In contrast, the carbapenem family includes a variety of semisynthetic drugs ( imipenem , meropenem , and doripenem ) that provide very broad-spectrum activity against gram-positive and gram-negative bacterial pathogens. The drug vancomycin , a member of a class of compounds called the glycopeptides , was discovered in the 1950s as a natural antibiotic from the actinomycete Amycolatopsis orientalis . Similar to the β-lactams, vancomycin inhibits cell wall biosynthesis and is bactericidal. However, in contrast to the β-lactams, the structure of vancomycin is not similar to that of cell-wall peptidoglycan subunits and does not directly inactivate penicillin-binding proteins. Rather, vancomycin is a very large, complex molecule that binds to the end of the peptide chain of cell wall precursors, creating a structural blockage that prevents the cell wall subunits from being incorporated into the growing N-acetylglucosamine and N-acetylmuramic acid (NAM-NAG) backbone of the peptidoglycan structure ( transglycosylation ). Vancomycin also structurally blocks transpeptidation . Vancomycin is bactericidal against gram-positive bacterial pathogens, but it is not active against gram-negative bacteria because of its inability to penetrate the protective outer membrane. The drug bacitracin consists of a group of structurally similar peptide antibiotics originally isolated from Bacillus subtilis . Bacitracin blocks the activity of a specific cell-membrane molecule that is responsible for the movement of peptidoglycan precursors from the cytoplasm to the exterior of the cell, ultimately preventing their incorporation into the cell wall. Bacitracin is effective against a wide range of bacteria, including gram-positive organisms found on the skin, such as Staphylococcus and Streptococcus . Although it may be administered orally or intramuscularly in some circumstances, bacitracin has been shown to be nephrotoxic (damaging to the kidneys). Therefore, it is more commonly combined with neomycin and polymyxin in topical ointments such as Neosporin . Drugs that Inhibit Bacterial Cell Wall Synthesis Mechanism of Action Drug Class Specific Drugs Natural or Semisynthetic Spectrum of Activity Interact directly with PBPs and inhibit transpeptidase activity Penicillins Penicillin G, penicillin V Natural Narrow-spectrum against gram-positive and a few gram-negative bacteria Ampicillin, amoxicillin Semisynthetic Narrow-spectrum against gram-positive bacteria but with increased gram-negative spectrum Methicillin Semisynthetic Narrow-spectrum against gram-positive bacteria only, including strains producing penicillinase Cephalosporins Cephalosporin C Natural Narrow-spectrum similar to penicillin but with increased gram-negative spectrum First-generation cephalosporins Semisynthetic Narrow-spectrum similar to cephalosporin C Second-generation cephalosporins Semisynthetic Narrow-spectrum but with increased gram-negative spectrum compared with first generation Third- and fourth-generation cephalosporins Semisynthetic Broad-spectrum against gram-positive and gram-negative bacteria, including some β-lactamase producers Fifth-generation cephalosporins Semisynthetic Broad-spectrum against gram-positive and gram-negative bacteria, including MRSA Monobactams Aztreonam Semisynthetic Narrow-spectrum against gram-negative bacteria, including some β-lactamase producers Carbapenems Imipenem, meropenem, doripenem Semisynthetic Broadest spectrum of the β-lactams against gram-positive and gram-negative bacteria, including many β-lactamase producers Large molecules that bind to the peptide chain of peptidoglycan subunits, blocking transglycosylation and transpeptidation Glycopeptides Vancomycin Natural Narrow spectrum against gram-positive bacteria only, including multidrug-resistant strains Block transport of peptidoglycan subunits across cytoplasmic membrane Bacitracin Bacitracin Natural Broad-spectrum against gram-positive and gram-negative bacteria Table 14.2 Check Your Understanding Describe the mode of action of β-lactams. Inhibitors of Protein Biosynthesis The cytoplasmic ribosomes found in animal cells (80S) are structurally distinct from those found in bacterial cells (70S), making protein biosynthesis a good selective target for antibacterial drugs. Several types of protein biosynthesis inhibitors are discussed in this section and are summarized in Figure 14.11 . Protein Synthesis Inhibitors That Bind the 30S Subunit Aminoglycosides are large, highly polar antibacterial drugs that bind to the 30S subunit of bacterial ribosomes, impairing the proofreading ability of the ribosomal complex. This impairment causes mismatches between codons and anticodons, resulting in the production of proteins with incorrect amino acids and shortened proteins that insert into the cytoplasmic membrane. Disruption of the cytoplasmic membrane by the faulty proteins kills the bacterial cells. The aminoglycosides , which include drugs such as streptomycin , gentamicin , neomycin , and kanamycin , are potent broad-spectrum antibacterials. However, aminoglycosides have been shown to be nephrotoxic (damaging to kidney), neurotoxic (damaging to the nervous system), and ototoxic (damaging to the ear). Another class of antibacterial compounds that bind to the 30S subunit is the tetracyclines . In contrast to aminoglycosides, these drugs are bacteriostatic and inhibit protein synthesis by blocking the association of tRNAs with the ribosome during translation. Naturally occurring tetracyclines produced by various strains of Streptomyces were first discovered in the 1940s, and several semisynthetic tetracyclines, including doxycycline and tigecycline have also been produced. Although the tetracyclines are broad spectrum in their coverage of bacterial pathogens, side effects that can limit their use include phototoxicity , permanent discoloration of developing teeth, and liver toxicity with high doses or in patients with kidney impairment. Protein Synthesis Inhibitors That Bind the 50S Subunit There are several classes of antibacterial drugs that work through binding to the 50S subunit of bacterial ribosomes. The macrolide antibacterial drugs have a large, complex ring structure and are part of a larger class of naturally produced secondary metabolites called polyketides , complex compounds produced in a stepwise fashion through the repeated addition of two-carbon units by a mechanism similar to that used for fatty acid synthesis. Macrolides are broad-spectrum, bacteriostatic drugs that block elongation of proteins by inhibiting peptide bond formation between specific combinations of amino acids. The first macrolide was erythromycin . It was isolated in 1952 from Streptomyces erythreus and prevents translocation. Semisynthetic macrolides include azithromycin and telithromycin. Compared with erythromycin, azithromycin has a broader spectrum of activity, fewer side effects, and a significantly longer half-life (1.5 hours for erythromycin versus 68 hours for azithromycin) that allows for once-daily dosing and a short 3-day course of therapy (i.e., Zpac formulation) for most infections. Telithromycin is the first semisynthetic within the class known as ketolides. Although telithromycin shows increased potency and activity against macrolide-resistant pathogens, the US Food and Drug Administration (FDA) has limited its use to treatment of community-acquired pneumonia and requires the strongest “black box warning” label for the drug because of serious hepatotoxicity. The lincosamides include the naturally produced lincomycin and semisynthetic clindamycin . Although structurally distinct from macrolides, lincosamides are similar in their mode of action to the macrolides through binding to the 50S ribosomal subunit and preventing peptide bond formation. Lincosamides are particularly active against streptococcal and staphylococcal infections. The drug chloramphenicol represents yet another structurally distinct class of antibacterials that also bind to the 50S ribosome, inhibiting peptide bond formation. Chloramphenicol, produced by Streptomyces venezuelae , was discovered in 1947; in 1949, it became the first broad-spectrum antibiotic that was approved by the FDA. Although it is a natural antibiotic, it is also easily synthesized and was the first antibacterial drug synthetically mass produced. As a result of its mass production, broad-spectrum coverage, and ability to penetrate into tissues efficiently, chloramphenicol was historically used to treat a wide range of infections, from meningitis to typhoid fever to conjunctivitis . Unfortunately, serious side effects, such as lethal gray baby syndrome , and suppression of bone marrow production, have limited its clinical role. Chloramphenicol also causes anemia in two different ways. One mechanism involves the targeting of mitochondrial ribosomes within hematopoietic stem cells, causing a reversible, dose-dependent suppression of blood cell production. Once chloramphenicol dosing is discontinued, blood cell production returns to normal. This mechanism highlights the similarity between 70S ribosomes of bacteria and the 70S ribosomes within our mitochondria. The second mechanism of anemia is idiosyncratic (i.e., the mechanism is not understood), and involves an irreversible lethal loss of blood cell production known as aplastic anemia . This mechanism of aplastic anemia is not dose dependent and can develop after therapy has stopped. Because of toxicity concerns, chloramphenicol usage in humans is now rare in the United States and is limited to severe infections unable to be treated by less toxic antibiotics. Because its side effects are much less severe in animals, it is used in veterinary medicine. The oxazolidinones , including linezolid , are a new broad-spectrum class of synthetic protein synthesis inhibitors that bind to the 50S ribosomal subunit of both gram-positive and gram-negative bacteria. However, their mechanism of action seems somewhat different from that of the other 50S subunit-binding protein synthesis inhibitors already discussed. Instead, they seem to interfere with formation of the initiation complex (association of the 50S subunit, 30S subunit, and other factors) for translation, and they prevent translocation of the growing protein from the ribosomal A site to the P site. Table 14.3 summarizes the protein synthesis inhibitors. Drugs That Inhibit Bacterial Protein Synthesis Molecular Target Mechanism of Action Drug Class Specific Drugs Bacteriostatic or Bactericidal Spectrum of Activity 30S subunit Causes mismatches between codons and anticodons, leading to faulty proteins that insert into and disrupt cytoplasmic membrane Aminoglycosides Streptomycin, gentamicin, neomycin, kanamycin Bactericidal Broad spectrum Blocks association of tRNAs with ribosome Tetracyclines Tetracycline, doxycycline, tigecycline Bacteriostatic Broad spectrum 50S subunit Blocks peptide bond formation between amino acids Macrolides Erythromycin, azithromycin, telithromycin Bacteriostatic Broad spectrum Lincosamides Lincomycin, clindamycin Bacteriostatic Narrow spectrum Not applicable Chloramphenicol Bacteriostatic Broad spectrum Interferes with the formation of the initiation complex between 50S and 30S subunits and other factors. Oxazolidinones Linezolid Bacteriostatic Broad spectrum Table 14.3 Check Your Understanding Compare and contrast the different types of protein synthesis inhibitors. Inhibitors of Membrane Function A small group of antibacterials target the bacterial membrane as their mode of action ( Table 14.4 ). The polymyxins are natural polypeptide antibiotics that were first discovered in 1947 as products of Bacillus polymyxa ; only polymyxin B and polymyxin E ( colistin ) have been used clinically. They are lipophilic with detergent-like properties and interact with the lipopolysaccharide component of the outer membrane of gram-negative bacteria, ultimately disrupting both their outer and inner membranes and killing the bacterial cells. Unfortunately, the membrane-targeting mechanism is not a selective toxicity , and these drugs also target and damage the membrane of cells in the kidney and nervous system when administered systemically. Because of these serious side effects and their poor absorption from the digestive tract, polymyxin B is used in over-the-counter topical antibiotic ointments (e.g., Neosporin ), and oral colistin was historically used only for bowel decontamination to prevent infections originating from bowel microbes in immunocompromised patients or for those undergoing certain abdominal surgeries. However, the emergence and spread of multidrug-resistant pathogens has led to increased use of intravenous colistin in hospitals, often as a drug of last resort to treat serious infections. The antibacterial daptomycin is a cyclic lipopeptide produced by Streptomyces roseosporus that seems to work like the polymyxins, inserting in the bacterial cell membrane and disrupting it. However, in contrast to polymyxin B and colistin, which target only gram-negative bacteria, daptomycin specifically targets gram-positive bacteria. It is typically administered intravenously and seems to be well tolerated, showing reversible toxicity in skeletal muscles. Drugs That Inhibit Bacterial Membrane Function Mechanism of Action Drug Class Specific Drugs Spectrum of Activity Clinical Use Interacts with lipopolysaccharide in the outer membrane of gram-negative bacteria, killing the cell through the eventual disruption of the outer membrane and cytoplasmic membrane Polymyxins Polymyxin B Narrow spectrum against gram-negative bacteria, including multidrug-resistant strains Topical preparations to prevent infections in wounds Polymyxin E (colistin) Narrow spectrum against gram-negative bacteria, including multidrug-resistant strains Oral dosing to decontaminate bowels to prevent infections in immunocompromised patients or patients undergoing invasive surgery/procedures. Intravenous dosing to treat serious systemic infections caused by multidrug-resistant pathogens Inserts into the cytoplasmic membrane of gram-positive bacteria, disrupting the membrane and killing the cell Lipopeptide Daptomycin Narrow spectrum against gram-positive bacteria, including multidrug-resistant strains Complicated skin and skin-structure infections and bacteremia caused by gram-positive pathogens, including MRSA Table 14.4 Check Your Understanding How do polymyxins inhibit membrane function? Inhibitors of Nucleic Acid Synthesis Some antibacterial drugs work by inhibiting nucleic acid synthesis ( Table 14.5 ). For example, metronidazole is a semisynthetic member of the nitroimidazole family that is also an antiprotozoan. It interferes with DNA replication in target cells. The drug rifampin is a semisynthetic member of the rifamycin family and functions by blocking RNA polymerase activity in bacteria. The RNA polymerase enzymes in bacteria are structurally different from those in eukaryotes, providing for selective toxicity against bacterial cells. It is used for the treatment of a variety of infections, but its primary use, often in a cocktail with other antibacterial drugs, is against mycobacteria that cause tuberculosis . Despite the selectivity of its mechanism, rifampin can induce liver enzymes to increase metabolism of other drugs being administered (antagonism), leading to hepatotoxicity (liver toxicity) and negatively influencing the bioavailability and therapeutic effect of the companion drugs. One member of the quinolone family, a group of synthetic antimicrobials, is nalidixic acid . It was discovered in 1962 as a byproduct during the synthesis of chloroquine , an antimalarial drug. Nalidixic acid selectively inhibits the activity of bacterial DNA gyrase, blocking DNA replication. Chemical modifications to the original quinolone backbone have resulted in the production of fluoroquinolones , like ciprofloxacin and levofloxacin , which also inhibit the activity of DNA gyrase. Ciprofloxacin and levofloxacin are effective against a broad spectrum of gram-positive or gram-negative bacteria, and are among the most commonly prescribed antibiotics used to treat a wide range of infections, including urinary tract infections, respiratory infections, abdominal infections, and skin infections. However, despite their selective toxicity against DNA gyrase, side effects associated with different fluoroquinolones include phototoxicity , neurotoxicity , cardiotoxicity , glucose metabolism dysfunction, and increased risk for tendon rupture. Drugs That Inhibit Bacterial Nucleic Acid Synthesis Mechanisms of Action Drug Class Specific Drugs Spectrum of activity Clinical Use Inhibits bacterial RNA polymerase activity and blocks transcription, killing the cell Rifamycin Rifampin Narrow spectrum with activity against gram-positive and limited numbers of gram-negative bacteria. Also active against Mycobacterium tuberculosis. Combination therapy for treatment of tuberculosis Inhibits the activity of DNA gyrase and blocks DNA replication, killing the cell Fluoroquinolones Ciprofloxacin, ofloxacin, moxifloxacin Broad spectrum against gram-positive and gram-negative bacteria Wide variety of skin and systemic infections Table 14.5 Check Your Understanding Why do inhibitors of bacterial nucleic acid synthesis not target host cells? Inhibitors of Metabolic Pathways Some synthetic drugs control bacterial infections by functioning as antimetabolites , competitive inhibitors for bacterial metabolic enzymes ( Table 14.6 ). The sulfonamides ( sulfa drugs ) are the oldest synthetic antibacterial agents and are structural analogues of para -aminobenzoic acid (PABA), an early intermediate in folic acid synthesis ( Figure 14.12 ). By inhibiting the enzyme involved in the production of dihydrofolic acid, sulfonamides block bacterial biosynthesis of folic acid and, subsequently, pyrimidines and purines required for nucleic acid synthesis. This mechanism of action provides bacteriostatic inhibition of growth against a wide spectrum of gram-positive and gram-negative pathogens. Because humans obtain folic acid from food instead of synthesizing it intracellularly, sulfonamides are selectively toxic for bacteria. However, allergic reactions to sulfa drugs are common. The sulfones are structurally similar to sulfonamides but are not commonly used today except for the treatment of Hansen’s disease ( leprosy ). Trimethoprim is a synthetic antimicrobial compound that serves as an antimetabolite within the same folic acid synthesis pathway as sulfonamides. However, trimethoprim is a structural analogue of dihydrofolic acid and inhibits a later step in the metabolic pathway ( Figure 14.12 ). Trimethoprim is used in combination with the sulfa drug sulfamethoxazole to treat urinary tract infection s, ear infection s, and bronchitis . As discussed, the combination of trimethoprim and sulfamethoxazole is an example of antibacterial synergy. When used alone, each antimetabolite only decreases production of folic acid to a level where bacteriostatic inhibition of growth occurs. However, when used in combination, inhibition of both steps in the metabolic pathway decreases folic acid synthesis to a level that is lethal to the bacterial cell. Because of the importance of folic acid during fetal development, sulfa drugs and trimethoprim use should be carefully considered during early pregnancy. The drug isoniazid is an antimetabolite with specific toxicity for mycobacteria and has long been used in combination with rifampin or streptomycin in the treatment of tuberculosis . It is administered as a prodrug, requiring activation through the action of an intracellular bacterial peroxidase enzyme, forming isoniazid-nicotinamide adenine dinucleotide (NAD) and isoniazid-nicotinamide adenine dinucleotide phosphate (NADP), ultimately preventing the synthesis of mycolic acid, which is essential for mycobacterial cell walls. Possible side effects of isoniazid use include hepatotoxicity , neurotoxicity , and hematologic toxicity ( anemia ). Antimetabolite Drugs Metabolic Pathway Target Mechanism of Action Drug Class Specific Drugs Spectrum of Activity Folic acid synthesis Inhibits the enzyme involved in production of dihydrofolic acid Sulfonamides Sulfamethoxazole Broad spectrum against gram-positive and gram-negative bacteria Sulfones Dapsone Inhibits the enzyme involved in the production of tetrahydrofolic acid Not applicable Trimethoprim Broad spectrum against gram-positive and gram-negative bacteria Mycolic acid synthesis Interferes with the synthesis of mycolic acid Not applicable Isoniazid Narrow spectrum against Mycobacterium spp., including M. tuberculosis Table 14.6 Check Your Understanding How do sulfonamides and trimethoprim selectively target bacteria? Inhibitor of ATP Synthase Bedaquiline, representing the synthetic antibacterial class of compounds called the diarylquinolines , uses a novel mode of action that specifically inhibits mycobacterial growth. Although the specific mechanism has yet to be elucidated, this compound appears to interfere with the function of ATP synthases, perhaps by interfering with the use of the hydrogen ion gradient for ATP synthesis by oxidative phosphorylation , leading to reduced ATP production. Due to its side effects , including hepatotoxicity and potentially lethal heart arrhythmia, its use is reserved for serious, otherwise untreatable cases of tuberculosis . Link to Learning To learn more about the general principles of antimicrobial therapy and bacterial modes of action, read this article for a general overview of antimicrobial therapy strategies and read this article on the mechanism of action of antimicrobial classes. Clinical Focus Part 2 Reading thorough Marisa’s health history, the doctor noticed that during her hospitalization in Vietnam, she was catheterized and received the antimicrobial drugs ceftazidime and metronidazole . Upon learning this, the doctor ordered a CT scan of Marisa’s abdomen to rule out appendicitis; the doctor also requested blood work to see if she had an elevated white blood cell count, and ordered a urine analysis test and urine culture to look for the presence of white blood cells, red blood cells, and bacteria. Marisa’s urine sample came back positive for the presence of bacteria, indicating a urinary tract infection (UTI). The doctor prescribed ciprofloxacin. In the meantime, her urine was cultured to grow the bacterium for further testing. What types of antimicrobials are typically prescribed for UTIs? Based upon the antimicrobial drugs she was given in Vietnam, which of the antimicrobials for treatment of a UTI would you predict to be ineffective? Jump to the next Clinical Focus box. Go back to the previous Clinical Focus box. 14.4 Mechanisms of Other Antimicrobial Drugs Learning Objective Explain the differences between modes of action of drugs that target fungi, protozoa, helminths, and viruses Because fungi, protozoa, and helminths are eukaryotic, their cells are very similar to human cells, making it more difficult to develop drugs with selective toxicity. Additionally, viruses replicate within human host cells, making it difficult to develop drugs that are selectively toxic to viruses or virus-infected cells. Despite these challenges, there are antimicrobial drugs that target fungi, protozoa, helminths, and viruses, and some even target more than one type of microbe. Table 14.7 , Table 14.8 , Table 14.9 , and Table 14.10 provide examples for antimicrobial drugs in these various classes. Antifungal Drugs The most common mode of action for antifungal drugs is the disruption of the cell membrane. Antifungals take advantage of small differences between fungi and humans in the biochemical pathways that synthesize sterols. The sterols are important in maintaining proper membrane fluidity and, hence, proper function of the cell membrane. For most fungi, the predominant membrane sterol is ergosterol . Because human cell membranes use cholesterol , instead of ergosterol, antifungal drugs that target ergosterol synthesis are selectively toxic ( Figure 14.13 ). The imidazoles are synthetic fungicides that disrupt ergosterol biosynthesis; they are commonly used in medical applications and also in agriculture to keep seeds and harvested crops from molding. Examples include miconazole , ketoconazole , and clotrimazole , which are used to treat fungal skin infections such as ringworm , specifically tinea pedis ( athlete’s foot ), tinea cruris ( jock itch ), and tinea corporis . These infections are commonly caused by dermatophytes of the genera Trichophyton , Epidermophyton , and Microsporum . Miconazole is also used predominantly for the treatment of vaginal yeast infections caused by the fungus Candida , and ketoconazole is used for the treatment of tinea versicolor and dandruff , which both can be caused by the fungus Malassezia . The triazole drugs, including fluconazole , also inhibit ergosterol biosynthesis. However, they can be administered orally or intravenously for the treatment of several types of systemic yeast infections, including oral thrush and cryptococcal meningitis , both of which are prevalent in patients with AIDS. The triazoles also exhibit more selective toxicity , compared with the imidazoles, and are associated with fewer side effects. The allylamines , a structurally different class of synthetic antifungal drugs, inhibit an earlier step in ergosterol biosynthesis. The most commonly used allylamine is terbinafine (marketed under the brand name Lamisil ), which is used topically for the treatment of dermatophytic skin infections like athlete’s foot , ringworm , and jock itch . Oral treatment with terbinafine is also used for the treatment of fingernail and toenail fungus, but it can be associated with the rare side effect of hepatotoxicity . The polyenes are a class of antifungal agents naturally produced by certain actinomycete soil bacteria and are structurally related to macrolides . These large, lipophilic molecules bind to ergosterol in fungal cytoplasmic membranes, thus creating pores. Common examples include nystatin and amphotericin B . Nystatin is typically used as a topical treatment for yeast infections of the skin, mouth, and vagina, but may also be used for intestinal fungal infections. The drug amphotericin B is used for systemic fungal infections like aspergillosis , cryptococcal meningitis , histoplasmosis , blastomycosis , and candidiasis . Amphotericin B was the only antifungal drug available for several decades, but its use is associated with some serious side effects, including nephrotoxicity (kidney toxicity). Amphotericin B is often used in combination with flucytosine , a fluorinated pyrimidine analog that is converted by a fungal-specific enzyme into a toxic product that interferes with both DNA replication and protein synthesis in fungi. Flucytosine is also associated with hepatotoxicity (liver toxicity) and bone marrow depression. Beyond targeting ergosterol in fungal cell membranes, there are a few antifungal drugs that target other fungal structures ( Figure 14.14 ). The echinocandins , including caspofungin, are a group of naturally produced antifungal compounds that block the synthesis of β(1→3) glucan found in fungal cell walls but not found in human cells. This drug class has the nickname “penicillin for fungi.” Caspofungin is used for the treatment of aspergillosis as well as systemic yeast infections. Although chitin is only a minor constituent of fungal cell walls, it is also absent in human cells, making it a selective target. The polyoxins and nikkomycins are naturally produced antifungals that target chitin synthesis. Polyoxins are used to control fungi for agricultural purposes, and nikkomycin Z is currently under development for use in humans to treat yeast infections and Valley fever ( coccidioidomycosis ), a fungal disease prevalent in the southwestern US. 12 12 Centers for Disease Control and Prevention. “Valley Fever: Awareness Is Key.” http://www.cdc.gov/features/valleyfever/. Accessed June 1, 2016. The naturally produced antifungal griseofulvin is thought to specifically disrupt fungal cell division by interfering with microtubules involved in spindle formation during mitosis. It was one of the first antifungals, but its use is associated with hepatotoxicity . It is typically administered orally to treat various types of dermatophytic skin infections when other topical antifungal treatments are ineffective. There are a few drugs that act as antimetabolites against fungal processes. For example, atovaquone , a representative of the naphthoquinone drug class, is a semisynthetic antimetabolite for fungal and protozoal versions of a mitochondrial cytochrome important in electron transport. Structurally, it is an analog of coenzyme Q , with which it competes for electron binding. It is particularly useful for the treatment of Pneumocystis pneumonia caused by Pneumocystis jirovecii . The antibacterial sulfamethoxazole-trimethoprim combination also acts as an antimetabolite against P. jirovecii . Table 14.7 shows the various therapeutic classes of antifungal drugs, categorized by mode of action, with examples of each. Common Antifungal Drugs Mechanism of Action Drug Class Specific Drugs Clinical Uses Inhibit ergosterol synthesis Imidazoles Miconazole, ketoconazole, clotrimazole Fungal skin infections and vaginal yeast infections Triazoles Fluconazole Systemic yeast infections, oral thrush, and cryptococcal meningitis Allylamines Terbinafine Dermatophytic skin infections (athlete’s foot, ring worm, jock itch), and infections of fingernails and toenails Bind ergosterol in the cell membrane and create pores that disrupt the membrane Polyenes Nystatin Used topically for yeast infections of skin, mouth, and vagina; also used for fungal infections of the intestine Amphotericin B Variety systemic fungal infections Inhibit cell wall synthesis Echinocandins Caspofungin Aspergillosis and systemic yeast infections Not applicable Nikkomycin Z Coccidioidomycosis (Valley fever) and yeast infections Inhibit microtubules and cell division Not applicable Griseofulvin Dermatophytic skin infections Table 14.7 Check Your Understanding How is disruption of ergosterol biosynthesis an effective mode of action for antifungals? Case in Point Treating a Fungal Infection of the Lungs Jack, a 48-year-old engineer, is HIV positive but generally healthy thanks to antiretroviral therapy (ART) . However, after a particularly intense week at work, he developed a fever and a dry cough. He assumed that he just had a cold or mild flu due to overexertion and didn’t think much of it. However, after about a week, he began to experience fatigue, weight loss, and shortness of breath. He decided to visit his physician, who found that Jack had a low level of blood oxygenation. The physician ordered blood testing, a chest X-ray, and the collection of an induced sputum sample for analysis. His X-ray showed a fine cloudiness and several pneumatoceles (thin-walled pockets of air), which indicated Pneumocystis pneumonia (PCP), a type of pneumonia caused by the fungus Pneumocystis jirovecii . Jack’s physician admitted him to the hospital and prescribed Bactrim , a combination of sulfamethoxazole and trimethoprim , to be administered intravenously. P. jirovecii is a yeast-like fungus with a life cycle similar to that of protozoans. As such, it was classified as a protozoan until the 1980s. It lives only in the lung tissue of infected persons and is transmitted from person to person, with many people exposed as children. Typically, P. jirovecii only causes pneumonia in immunocompromised individuals. Healthy people may carry the fungus in their lungs with no symptoms of disease. PCP is particularly problematic among HIV patients with compromised immune systems. PCP is usually treated with oral or intravenous Bactrim, but atovaquone or pentamidine (another antiparasitic drug) are alternatives. If not treated, PCP can progress, leading to a collapsed lung and nearly 100% mortality. Even with antimicrobial drug therapy, PCP still is responsible for 10% of HIV-related deaths. The cytological examination, using direct immunofluorescence assay (DFA), of a smear from Jack’s sputum sample confirmed the presence of P. jirovecii ( Figure 14.15 ). Additionally, the results of Jack’s blood tests revealed that his white blood cell count had dipped, making him more susceptible to the fungus. His physician reviewed his ART regimen and made adjustments. After a few days of hospitalization, Jack was released to continue his antimicrobial therapy at home. With the adjustments to his ART therapy, Jack’s CD4 counts began to increase and he was able to go back to work. Antiprotozoan Drugs There are a few mechanisms by which antiprotozoan drugs target infectious protozoans ( Table 14.9 ). Some are antimetabolites , such as atovaquone , proguanil , and artemisinins. Atovaquone, in addition to being antifungal, blocks electron transport in protozoans and is used for the treatment of protozoan infections including malaria , babesiosis , and toxoplasmosis . Proguanil is another synthetic antimetabolite that is processed in parasitic cells into its active form, which inhibits protozoan folic acid synthesis. It is often used in combination with atovaquone, and the combination is marketed as Malarone for both malaria treatment and prevention. Artemisinin, a plant-derived antifungal first discovered by Chinese scientists in the 1970s, is quite effective against malaria. Semisynthetic derivatives of artemisinin are more water soluble than the natural version, which makes them more bioavailable. Although the exact mechanism of action is unclear, artemisinins appear to act as prodrugs that are metabolized by target cells to produce reactive oxygen species (ROS) that damage target cells. Due to the rise in resistance to antimalarial drugs, artemisinins are also commonly used in combination with other antimalarial compounds in artemisinin-based combination therapy (ACT). Several antimetabolites are used for the treatment of toxoplasmosis caused by the parasite Toxoplasma gondii . The synthetic sulfa drug sulfadiazine competitively inhibits an enzyme in folic acid production in parasites and can be used to treat malaria and toxoplasmosis. Pyrimethamine is a synthetic drug that inhibits a different enzyme in the folic acid production pathway and is often used in combination with sulfadoxine (another sulfa drug) for the treatment of malaria or in combination with sulfadiazine for the treatment of toxoplasmosis . Side effects of pyrimethamine include decreased bone marrow activity that may cause increased bruising and low red blood cell counts. When toxicity is a concern, spiramycin , a macrolide protein synthesis inhibitor, is typically administered for the treatment of toxoplasmosis. Two classes of antiprotozoan drugs interfere with nucleic acid synthesis: nitroimidazoles and quinolines . Nitroimidazoles, including semisynthetic metronidazole , which was discussed previously as an antibacterial drug, and synthetic tinidazole , are useful in combating a wide variety of protozoan pathogens, such as Giardia lamblia , Entamoeba histolytica , and Trichomonas vaginalis . Upon introduction into these cells in low-oxygen environments, nitroimidazoles become activated and introduce DNA strand breakage, interfering with DNA replication in target cells. Unfortunately, metronidazole is associated with carcinogenesis (the development of cancer) in humans. Another type of synthetic antiprotozoan drug that has long been thought to specifically interfere with DNA replication in certain pathogens is pentamidine . It has historically been used for the treatment of African sleeping sickness (caused by the protozoan Trypanosoma brucei ) and leishmaniasis (caused by protozoa of the genus Leishmania ), but it is also an alternative treatment for the fungus Pneumocystis . Some studies indicate that it specifically binds to the DNA found within kinetoplasts (kDNA; long mitochondrion-like structures unique to trypanosomes ), leading to the cleavage of kDNA. However, nuclear DNA of both the parasite and host remain unaffected. It also appears to bind to tRNA, inhibiting the addition of amino acids to tRNA, thus preventing protein synthesis. Possible side effects of pentamidine use include pancreatic dysfunction and liver damage. The quinolines are a class of synthetic compounds related to quinine , which has a long history of use against malaria. Quinolines are thought to interfere with heme detoxification, which is necessary for the parasite’s effective breakdown of hemoglobin into amino acids inside red blood cells. The synthetic derivatives chloroquine, quinacrine (also called mepacrine ), and mefloquine are commonly used as antimalarials, and chloroquine is also used to treat amebiasis typically caused by Entamoeba histolytica . Long-term prophylactic use of chloroquine or mefloquine may result in serious side effects, including hallucinations or cardiac issues. Patients with glucose-6-phosphate dehydrogenase deficiency experience severe anemia when treated with chloroquine. Common Antiprotozoan Drugs Mechanism of Action Drug Class Specific Drugs Clinical Uses Inhibit electron transport in mitochondria Naphthoquinone Atovaquone Malaria, babesiosis, and toxoplasmosis Inhibit folic acid synthesis Not applicable Proquanil Combination therapy with atovaquone for malaria treatment and prevention Sulfonamide Sulfadiazine Malaria and toxoplasmosis Not applicable Pyrimethamine Combination therapy with sulfadoxine (sulfa drug) for malaria Produces damaging reactive oxygen species Not applicable Artemisinin Combination therapy to treat malaria Inhibit DNA synthesis Nitroimidazoles Metronidazole, tinidazole Infections caused by Giardia lamblia, Entamoeba histolytica, and Trichomonas vaginalis Not applicable Pentamidine African sleeping sickness and leishmaniasis Inhibit heme detoxification Quinolines Chloroquine Malaria and infections with E. histolytica Mepacrine, mefloquine Malaria Table 14.8 Check Your Understanding List two modes of action for antiprotozoan drugs. Antihelminthic Drugs Because helminths are multicellular eukaryotes like humans, developing drugs with selective toxicity against them is extremely challenging. Despite this, several effective classes have been developed ( Table 14.9 ). Synthetic benzimidazoles , like mebendazole and albendazole , bind to helminthic β-tubulin, preventing microtubule formation. Microtubules in the intestinal cells of the worms seem to be particularly affected, leading to a reduction in glucose uptake. Besides their activity against a broad range of helminths, benzimidazoles are also active against many protozoans, fungi, and viruses, and their use for inhibiting mitosis and cell cycle progression in cancer cells is under study. 13 Possible side effects of their use include liver damage and bone marrow suppression. 13 B. Chu et al. “A Benzimidazole Derivative Exhibiting Antitumor Activity Blocks EGFR and HER2 Activity and Upregulates DR5 in Breast Cancer Cells.” Cell Death and Disease 6 (2015):e1686 The avermectins are members of the macrolide family that were first discovered from a Japanese soil isolate, Streptomyces avermectinius . A more potent semisynthetic derivative of avermectin is ivermectin , which binds to glutamate-gated chloride channels specific to invertebrates including helminths, blocking neuronal transmission and causing starvation, paralysis, and death of the worms. Ivermectin is used to treat roundworm diseases, including onchocerciasis (also called river blindness , caused by the worm Onchocerca volvulus ) and strongyloidiasis (caused by the worm Strongyloides stercoralis or S. fuelleborni ). Ivermectin also can also treat parasitic insects like mites, lice, and bed bugs, and is nontoxic to humans. Niclosamide is a synthetic drug that has been used for over 50 years to treat tapeworm infections. Although its mode of action is not entirely clear, niclosamide appears to inhibit ATP formation under anaerobic conditions and inhibit oxidative phosphorylation in the mitochondria of its target pathogens. Niclosamide is not absorbed from the gastrointestinal tract, thus it can achieve high localized intestinal concentrations in patients. Recently, it has been shown to also have antibacterial, antiviral, and antitumor activities. 14 15 16 14 J.-X. Pan et al. “Niclosamide, An Old Antihelminthic Agent, Demonstrates Antitumor Activity by Blocking Multiple Signaling Pathways of Cancer Stem Cells.” Chinese Journal of Cancer 31 no. 4 (2012):178–184. 15 F. Imperi et al. “New Life for an Old Drug: The Anthelmintic Drug Niclosamide Inhibits Pseudomonas aeruginosa Quorum Sensing.” Antimicrobial Agents and Chemotherapy 57 no. 2 (2013):996-1005. 16 A. Jurgeit et al. “Niclosamide Is a Proton Carrier and Targets Acidic Endosomes with Broad Antiviral Effects.” PLoS Pathogens 8 no. 10 (2012):e1002976. Another synthetic antihelminthic drug is praziquantel , which used for the treatment of parasitic tapeworms and liver flukes , and is particularly useful for the treatment of schistosomiasis (caused by blood flukes from three genera of Schistosoma ). Its mode of action remains unclear, but it appears to cause the influx of calcium into the worm, resulting in intense spasm and paralysis of the worm. It is often used as a preferred alternative to niclosamide in the treatment of tapeworms when gastrointestinal discomfort limits niclosamide use. The thioxanthenones , another class of synthetic drugs structurally related to quinine , exhibit antischistosomal activity by inhibiting RNA synthesis. The thioxanthenone lucanthone and its metabolite hycanthone were the first used clinically, but serious neurological, gastrointestinal, cardiovascular, and hepatic side effects led to their discontinuation. Oxamniquine, a less toxic derivative of hycanthone, is only effective against S. mansoni , one of the three species known to cause schistosomiasis in humans. Praziquantel was developed to target the other two schistosome species, but concerns about increasing resistance have renewed interest in developing additional derivatives of oxamniquine to target all three clinically important schistosome species. Common Antihelminthic Drugs Mechanism of Action Drug Class Specific Drugs Clinical Uses Inhibit microtubule formation, reducing glucose uptake Benzimidazoles Mebendazole, albendazole Variety of helminth infections Block neuronal transmission, causing paralysis and starvation Avermectins Ivermectin Roundworm diseases, including river blindness and strongyloidiasis, and treatment of parasitic insects Inhibit ATP production Not applicable Niclosamide Intestinal tapeworm infections Induce calcium influx Not applicable Praziquantel Schistosomiasis (blood flukes) Inhibit RNA synthesis Thioxanthenones Lucanthone, hycanthone, oxamniquine Schistosomiasis (blood flukes) Table 14.9 Check Your Understanding Why are antihelminthic drugs difficult to develop? Antiviral Drugs Unlike the complex structure of fungi, protozoa, and helminths, viral structure is simple, consisting of nucleic acid, a protein coat, viral enzymes, and, sometimes, a lipid envelope. Furthermore, viruses are obligate intracellular pathogens that use the host’s cellular machinery to replicate. These characteristics make it difficult to develop drugs with selective toxicity against viruses. Many antiviral drugs are nucleoside analogs and function by inhibiting nucleic acid biosynthesis. For example, acyclovir (marketed as Zovirax ) is a synthetic analog of the nucleoside guanosine ( Figure 14.16 ). It is activated by the herpes simplex viral enzyme thymidine kinase and, when added to a growing DNA strand during replication, causes chain termination. Its specificity for virus-infected cells comes from both the need for a viral enzyme to activate it and the increased affinity of the activated form for viral DNA polymerase compared to host cell DNA polymerase. Acyclovir and its derivatives are frequently used for the treatment of herpes virus infections, including genital herpes , chickenpox , shingles , Epstein-Barr virus infections, and cytomegalovirus infections. Acyclovir can be administered either topically or systemically, depending on the infection. One possible side effect of its use includes nephrotoxicity . The drug adenine-arabinoside , marketed as vidarabine , is a synthetic analog to deoxyadenosine that has a mechanism of action similar to that of acyclovir. It is also effective for the treatment of various human herpes viruses. However, because of possible side effects involving low white blood cell counts and neurotoxicity , treatment with acyclovir is now preferred. Ribavirin, another synthetic guanosine analog, works by a mechanism of action that is not entirely clear. It appears to interfere with both DNA and RNA synthesis, perhaps by reducing intracellular pools of guanosine triphosphate (GTP). Ribavarin also appears to inhibit the RNA polymerase of hepatitis C virus. It is primarily used for the treatment of the RNA viruses like hepatitis C (in combination therapy with interferon) and respiratory syncytial virus . Possible side effects of ribavirin use include anemia and developmental effects on unborn children in pregnant patients. In recent years, another nucleotide analog, sofosbuvir ( Solvaldi ), has also been developed for the treatment of hepatitis C. Sofosbuvir is a uridine analog that interferes with viral polymerase activity. It is commonly coadministered with ribavirin, with and without interferon . Inhibition of nucleic acid synthesis is not the only target of synthetic antivirals. Although the mode of action of amantadine and its relative rimantadine are not entirely clear, these drugs appear to bind to a transmembrane protein that is involved in the escape of the influenza virus from endosomes. Blocking escape of the virus also prevents viral RNA release into host cells and subsequent viral replication. Increasing resistance has limited the use of amantadine and rimantadine in the treatment of influenza A. Use of amantadine can result in neurological side effects, but the side effects of rimantadine seem less severe. Interestingly, because of their effects on brain chemicals such as dopamine and NMDA (N-methyl D-aspartate), amantadine and rimantadine are also used for the treatment of Parkinson’s disease . Neuraminidase inhibitors, including olsetamivir ( Tamiflu ), zanamivir ( Relenza ), and peramivir ( Rapivab ), specifically target influenza viruses by blocking the activity of influenza virus neuraminidase , preventing the release of the virus from infected cells. These three antivirals can decrease flu symptoms and shorten the duration of illness, but they differ in their modes of administration: olsetamivir is administered orally, zanamivir is inhaled, and peramivir is administered intravenously. Resistance to these neuraminidase inhibitors still seems to be minimal. Pleconaril is a synthetic antiviral under development that showed promise for the treatment of picornaviruses . Use of pleconaril for the treatment of the common cold caused by rhinoviruses was not approved by the FDA in 2002 because of lack of proven effectiveness, lack of stability, and association with irregular menstruation. Its further development for this purpose was halted in 2007. However, pleconaril is still being investigated for use in the treatment of life-threatening complications of enteroviruses , such as meningitis and sepsis . It is also being investigated for use in the global eradication of a specific enterovirus, polio . 17 Pleconaril seems to work by binding to the viral capsid and preventing the uncoating of viral particles inside host cells during viral infection. 17 M.J. Abzug. “The Enteroviruses: Problems in Need of Treatments.” Journal of Infection 68 no. S1 (2014):108–14. Viruses with complex life cycles, such as HIV , can be more difficult to treat. First, HIV targets CD4-positive white blood cells, which are necessary for a normal immune response to infection. Second, HIV is a retrovirus , meaning that it converts its RNA genome into a DNA copy that integrates into the host cell’s genome, thus hiding within host cell DNA. Third, the HIV reverse transcriptase lacks proofreading activity and introduces mutations that allow for rapid development of antiviral drug resistance. To help prevent the emergence of resistance, a combination of specific synthetic antiviral drugs is typically used in ART for HIV ( Figure 14.17 ). The reverse transcriptase inhibitors block the early step of converting viral RNA genome into DNA, and can include competitive nucleoside analog inhibitors (e.g., azidothymidine/zidovudine , or AZT) and non-nucleoside noncompetitive inhibitors (e.g., etravirine ) that bind reverse transcriptase and cause an inactivating conformational change. Drugs called protease inhibitors (e.g., ritonavir ) block the processing of viral proteins and prevent viral maturation. Protease inhibitors are also being developed for the treatment of other viral types. 18 For example, simeprevir ( Olysio ) has been approved for the treatment of hepatitis C and is administered with ribavirin and interferon in combination therapy. The integrase inhibitors (e.g., raltegravir ), block the activity of the HIV integrase responsible for the recombination of a DNA copy of the viral genome into the host cell chromosome. Additional drug classes for HIV treatment include the CCR5 antagonists and the fusion inhibitors (e.g., enfuviritide ), which prevent the binding of HIV to the host cell coreceptor (chemokine receptor type 5 [CCR5]) and the merging of the viral envelope with the host cell membrane, respectively. Table 14.10 shows the various therapeutic classes of antiviral drugs, categorized by mode of action, with examples of each. 18 B.L. Pearlman. “Protease Inhibitors for the Treatment of Chronic Hepatitis C Genotype-1 Infection: The New Standard of Care.” Lancet Infectious Diseases 12 no. 9 (2012):717–728. Common Antiviral Drugs Mechanism of Action Drug Clinical Uses Nucleoside analog inhibition of nucleic acid synthesis Acyclovir Herpes virus infections Azidothymidine/zidovudine (AZT) HIV infections Ribavirin Hepatitis C virus and respiratory syncytial virus infections Vidarabine Herpes virus infections Sofosbuvir Hepatitis C virus infections Non-nucleoside noncompetitive inhibition Etravirine HIV infections Inhibit escape of virus from endosomes Amantadine, rimantadine Infections with influenza virus Inhibit neuraminadase Olsetamivir, zanamivir, peramivir Infections with influenza virus Inhibit viral uncoating Pleconaril Serious enterovirus infections Inhibition of protease Ritonavir HIV infections Simeprevir Hepatitis C virus infections Inhibition of integrase Raltegravir HIV infections Inhibition of membrane fusion Enfuviritide HIV infections Table 14.10 Check Your Understanding Why is HIV difficult to treat with antivirals? Link to Learning To learn more about the various classes of antiretroviral drugs used in the ART of HIV infection, explore each of the drugs in the HIV drug classes provided by US Department of Health and Human Services at this website. 14.5 Drug Resistance Learning Objectives Explain the concept of drug resistance Describe how microorganisms develop or acquire drug resistance Describe the different mechanisms of antimicrobial drug resistance Antimicrobial resistance is not a new phenomenon. In nature, microbes are constantly evolving in order to overcome the antimicrobial compounds produced by other microorganisms. Human development of antimicrobial drugs and their widespread clinical use has simply provided another selective pressure that promotes further evolution. Several important factors can accelerate the evolution of drug resistance . These include the overuse and misuse of antimicrobials, inappropriate use of antimicrobials, subtherapeutic dosing, and patient noncompliance with the recommended course of treatment. Exposure of a pathogen to an antimicrobial compound can select for chromosomal mutations conferring resistance, which can be transferred vertically to subsequent microbial generations and eventually become predominant in a microbial population that is repeatedly exposed to the antimicrobial. Alternatively, many genes responsible for drug resistance are found on plasmids or in transposons that can be transferred easily between microbes through horizontal gene transfer (see How Asexual Prokaryotes Achieve Genetic Diversity ). Transposons also have the ability to move resistance genes between plasmids and chromosomes to further promote the spread of resistance. Mechanisms for Drug Resistance There are several common mechanisms for drug resistance, which are summarized in Figure 14.18 . These mechanisms include enzymatic modification of the drug, modification of the antimicrobial target, and prevention of drug penetration or accumulation. Drug Modification or Inactivation Resistance genes may code for enzymes that chemically modify an antimicrobial, thereby inactivating it, or destroy an antimicrobial through hydrolysis. Resistance to many types of antimicrobials occurs through this mechanism. For example, aminoglycoside resistance can occur through enzymatic transfer of chemical groups to the drug molecule, impairing the binding of the drug to its bacterial target. For β-lactams , bacterial resistance can involve the enzymatic hydrolysis of the β-lactam bond within the β-lactam ring of the drug molecule. Once the β-lactam bond is broken, the drug loses its antibacterial activity. This mechanism of resistance is mediated by β-lactamases , which are the most common mechanism of β-lactam resistance. Inactivation of rifampin commonly occurs through glycosylation , phosphorylation , or adenosine diphosphate (ADP) ribosylation, and resistance to macrolides and lincosamides can also occur due to enzymatic inactivation of the drug or modification. Prevention of Cellular Uptake or Efflux Microbes may develop resistance mechanisms that involve inhibiting the accumulation of an antimicrobial drug, which then prevents the drug from reaching its cellular target. This strategy is common among gram-negative pathogens and can involve changes in outer membrane lipid composition, porin channel selectivity, and/or porin channel concentrations. For example, a common mechanism of carbapenem resistance among Pseudomonas aeruginosa is to decrease the amount of its OprD porin, which is the primary portal of entry for carbapenems through the outer membrane of this pathogen. Additionally, many gram-positive and gram-negative pathogenic bacteria produce efflux pump s that actively transport an antimicrobial drug out of the cell and prevent the accumulation of drug to a level that would be antibacterial. For example, resistance to β-lactams, tetracyclines , and fluoroquinolones commonly occurs through active efflux out of the cell, and it is rather common for a single efflux pump to have the ability to translocate multiple types of antimicrobials. Target Modification Because antimicrobial drugs have very specific targets, structural changes to those targets can prevent drug binding, rendering the drug ineffective. Through spontaneous mutations in the genes encoding antibacterial drug targets, bacteria have an evolutionary advantage that allows them to develop resistance to drugs. This mechanism of resistance development is quite common. Genetic changes impacting the active site of penicillin-binding proteins (PBPs) can inhibit the binding of β-lactam drugs and provide resistance to multiple drugs within this class. This mechanism is very common among strains of Streptococcus pneumoniae , which alter their own PBPs through genetic mechanisms. In contrast, strains of Staphylococcus aureus develop resistance to methicillin ( MRSA ) through the acquisition of a new low-affinity PBP, rather than structurally alter their existing PBPs. Not only does this new low-affinity PBP provide resistance to methicillin but it provides resistance to virtually all β-lactam drugs, with the exception of the newer fifth-generation cephalosporins designed specifically to kill MRSA. Other examples of this resistance strategy include alterations in ribosome subunits, providing resistance to macrolides, tetracyclines, and aminoglycosides; lipopolysaccharide (LPS) structure, providing resistance to polymyxins ; RNA polymerase, providing resistance to rifampin ; DNA gyrase, providing resistance to fluoroquinolones; metabolic enzymes, providing resistance to sulfa drugs , sulfones , and trimethoprim ; and peptidoglycan subunit peptide chains, providing resistance to glycopeptides . Target Overproduction or Enzymatic Bypass When an antimicrobial drug functions as an antimetabolite, targeting a specific enzyme to inhibit its activity, there are additional ways that microbial resistance may occur. First, the microbe may overproduce the target enzyme such that there is a sufficient amount of antimicrobial-free enzyme to carry out the proper enzymatic reaction. Second, the bacterial cell may develop a bypass that circumvents the need for the functional target enzyme. Both of these strategies have been found as mechanisms of sulfonamide resistance . Vancomycin resistance among S. aureus has been shown to involve the decreased cross-linkage of peptide chains in the bacterial cell wall, which provides an increase in targets for vancomycin to bind to in the outer cell wall. Increased binding of vancomycin in the outer cell wall provides a blockage that prevents free drug molecules from penetrating to where they can block new cell wall synthesis. Target Mimicry A recently discovered mechanism of resistance called target mimicry involves the production of proteins that prevent drugs from binding to their bacterial cellular targets. For example, fluoroquinolone resistance by Mycobacterium tuberculosis can involve the production of a protein that resembles DNA. This protein is called MfpA (Mycobacterium fluoroquinolone resistance protein A). The mimicry of DNA by MfpA results in DNA gyrase binding to MfpA, preventing the binding of fluoroquinolones to DNA gyrase. Check Your Understanding List several mechanisms for drug resistance. Multidrug-Resistant Microbes and Cross Resistance From a clinical perspective, our greatest concerns are multidrug-resistant microbes (MDRs) and cross resistance. MDRs are colloquially known as “ superbugs ” and carry one or more resistance mechanism(s), making them resistant to multiple antimicrobials. In cross-resistance , a single resistance mechanism confers resistance to multiple antimicrobial drugs. For example, having an efflux pump that can export multiple antimicrobial drugs is a common way for microbes to be resistant to multiple drugs by using a single resistance mechanism. In recent years, several clinically important superbugs have emerged, and the CDC reports that superbugs are responsible for more than 2 million infections in the US annually, resulting in at least 23,000 fatalities. 19 Several of the superbugs discussed in the following sections have been dubbed the ESKAPE pathogens . This acronym refers to the names of the pathogens ( Enterococcus faecium , Staphylococcus aureus , Klebsiella pneumoniae , Acinetobacter baumannii , Pseudomonas aeruginosa and Enterobacter spp. ) but it is also fitting in that these pathogens are able to “escape” many conventional forms of antimicrobial therapy. As such, infections by ESKAPE pathogens can be difficult to treat and they cause a large number of nosocomial infections. 19 Centers for Disease Control and Prevention. “Antibiotic/Antimicrobial Resistance.” http://www.cdc.gov/drugresistance/index.html. Accessed June 2, 2016. Methicillin-Resistant Staphylococcus aureus (MRSA) Methicillin, a semisynthetic penicillin, was designed to resist inactivation by β-lactamases. Unfortunately, soon after the introduction of methicillin to clinical practice, methicillin-resistant strains of S. aureus appeared and started to spread. The mechanism of resistance, acquisition of a new low-affinity PBP, provided S. aureus with resistance to all available β-lactams. Strains of methicillin-resistant S. aureus (MRSA) are widespread opportunistic pathogens and a particular concern for skin and other wound infections, but may also cause pneumonia and septicemia . Although originally a problem in health-care settings (hospital-acquired MRSA [HA-MRSA]), MRSA infections are now also acquired through contact with contaminated members of the general public, called community-associated MRSA (CA-MRSA). Approximately one-third of the population carries S. aureus as a member of their normal nasal microbiota without illness, and about 6% of these strains are methicillin resistant. 20 21 20 A.S. Kalokhe et al. “Multidrug-Resistant Tuberculosis Drug Susceptibility and Molecular Diagnostic Testing: A Review of the Literature. American Journal of the Medical Sciences 345 no. 2 (2013):143–148. 21 Centers for Disease Control and Prevention. “Methicillin-Resistant Staphylococcus aureus (MRSA): General Information About MRSA in the Community.” http://www.cdc.gov/mrsa/community/index.html. Accessed June 2, 2016 Micro Connections Clavulanic Acid: Penicillin’s Little Helper With the introduction of penicillin in the early 1940s, and its subsequent mass production, society began to think of antibiotics as miracle cures for a wide range of infectious diseases. Unfortunately, as early as 1945, penicillin resistance was first documented and started to spread. Greater than 90% of current S. aureus clinical isolates are resistant to penicillin. 22 22 F.D. Lowy. “Antimicrobial Resistance: The Example of Staphylococcus aureus .” Journal of Clinical Investigation 111 no. 9 (2003):1265–1273. Although developing new antimicrobial drugs is one solution to this problem, scientists have explored new approaches, including the development of compounds that inactivate resistance mechanisms. The development of clavulanic acid represents an early example of this strategy. Clavulanic acid is a molecule produced by the bacterium Streptococcus clavuligerus . It contains a β-lactam ring , making it structurally similar to penicillin and other β-lactams , but shows no clinical effectiveness when administered on its own. Instead, clavulanic acid binds irreversibly within the active site of β-lactamases and prevents them from inactivating a coadministered penicillin. Clavulanic acid was first developed in the 1970s and was mass marketed in combination with amoxicillin beginning in the 1980s under the brand name Augmentin. As is typically the case, resistance to the amoxicillin-clavulanic acid combination soon appeared. Resistance most commonly results from bacteria increasing production of their β-lactamase and overwhelming the inhibitory effects of clavulanic acid, mutating their β-lactamase so it is no longer inhibited by clavulanic acid, or from acquiring a new β-lactamase that is not inhibited by clavulanic acid. Despite increasing resistance concerns, clavulanic acid and related β-lactamase inhibitors (sulbactam and tazobactam) represent an important new strategy: the development of compounds that directly inhibit antimicrobial resistance-conferring enzymes. Vancomycin-Resistant Enterococci and Staphylococcus aureus Vancomycin is only effective against gram-positive organisms, and it is used to treat wound infections, septic infections, endocarditis, and meningitis that are caused by pathogens resistant to other antibiotics. It is considered one of the last lines of defense against such resistant infections, including MRSA. With the rise of antibiotic resistance in the 1970s and 1980s, vancomycin use increased, and it is not surprising that we saw the emergence and spread of vancomycin-resistant enterococci (VRE) , vancomycin-resistant S. aureus (VRSA) , and vancomycin-intermediate S. aureus (VISA) . The mechanism of vancomycin resistance among enterococci is target modification involving a structural change to the peptide component of the peptidoglycan subunits, preventing vancomycin from binding. These strains are typically spread among patients in clinical settings by contact with health-care workers and contaminated surfaces and medical equipment. VISA and VRSA strains differ from each other in the mechanism of resistance and the degree of resistance each mechanism confers. VISA strains exhibit intermediate resistance, with a minimum inhibitory concentration (MIC) of 4–8 μg/mL, and the mechanism involves an increase in vancomycin targets. VISA strains decrease the crosslinking of peptide chains in the cell wall, providing an increase in vancomycin targets that trap vancomycin in the outer cell wall. In contrast, VRSA strains acquire vancomycin resistance through horizontal transfer of resistance genes from VRE, an opportunity provided in individuals coinfected with both VRE and MRSA. VRSA exhibit a higher level of resistance, with MICs of 16 μg/mL or higher. 23 In the case of all three types of vancomycin-resistant bacteria, rapid clinical identification is necessary so proper procedures to limit spread can be implemented. The oxazolidinones like linezolid are useful for the treatment of these vancomycin-resistant, opportunistic pathogens, as well as MRSA. 23 Centers for Disease Control and Prevention. “Healthcare-Associated Infections (HIA): General Information about VISA/VRSA.” http://www.cdc.gov/HAI/organisms/visa_vrsa/visa_vrsa.html. Accessed June 2, 2016. Extended-Spectrum β-Lactamase–Producing Gram-Negative Pathogens Gram-negative pathogens that produce extended-spectrum β-lactamases (ESBLs) show resistance well beyond just penicillins. The spectrum of β-lactams inactivated by ESBLs provides for resistance to all penicillins , cephalosporins , monobactams , and the β-lactamase-inhibitor combinations, but not the carbapenems . An even greater concern is that the genes encoding for ESBLs are usually found on mobile plasmids that also contain genes for resistance to other drug classes (e.g., fluoroquinolones , aminoglycosides , tetracyclines ), and may be readily spread to other bacteria by horizontal gene transfer . These multidrug-resistant bacteria are members of the intestinal microbiota of some individuals, but they are also important causes of opportunistic infections in hospitalized patients, from whom they can be spread to other people. Carbapenem-Resistant Gram-Negative Bacteria The occurrence of carbapenem-resistant Enterobacteriaceae (CRE) and carbapenem resistance among other gram-negative bacteria (e.g., P. aeruginosa , Acinetobacter baumannii , Stenotrophomonas maltophila ) is a growing health-care concern. These pathogens develop resistance to carbapenems through a variety of mechanisms, including production of carbapenemases (broad-spectrum β-lactamases that inactivate all β-lactams, including carbapenems), active efflux of carbapenems out of the cell, and/or prevention of carbapenem entry through porin channels . Similar to concerns with ESBLs, carbapenem-resistant, gram-negative pathogens are usually resistant to multiple classes of antibacterials, and some have even developed pan-resistance (resistance to all available antibacterials). Infections with carbapenem-resistant, gram-negative pathogens commonly occur in health-care settings through interaction with contaminated individuals or medical devices, or as a result of surgery. Multidrug-Resistant Mycobacterium tuberculosis The emergence of multidrug-resistant Mycobacterium tuberculosis (MDR-TB) and extensively drug-resistant Mycobacterium tuberculosis ( XDR-TB ) is also of significant global concern. MDR-TB strains are resistant to both rifampin and isoniazid , the drug combination typically prescribed for treatment of tuberculosis. XDR-TB strains are additionally resistant to any fluoroquinolone and at least one of three other drugs ( amikacin , kanamycin , or capreomycin ) used as a second line of treatment, leaving these patients very few treatment options. Both types of pathogens are particularly problematic in immunocompromised persons, including those suffering from HIV infection. The development of resistance in these strains often results from the incorrect use of antimicrobials for tuberculosis treatment, selecting for resistance. Check Your Understanding How does drug resistance lead to superbugs? Link to Learning To learn more about the top 18 drug-resistant threats to the US, visit the CDC’s website. Micro Connections Factory Farming and Drug Resistance Although animal husbandry has long been a major part of agriculture in America, the rise of concentrated animal feeding operations (CAFOs) since the 1950s has brought about some new environmental issues, including the contamination of water and air with biological waste, and ethical issues regarding animal rights also are associated with growing animals in this way. Additionally, the increase in CAFOs involves the extensive use of antimicrobial drugs in raising livestock. Antimicrobials are used to prevent the development of infectious disease in the close quarters of CAFOs; however, the majority of antimicrobials used in factory farming are for the promotion of growth—in other words, to grow larger animals. The mechanism underlying this enhanced growth remains unclear. These antibiotics may not necessarily be the same as those used clinically for humans, but they are structurally related to drugs used for humans. As a result, use of antimicrobial drugs in animals can select for antimicrobial resistance, with these resistant bacteria becoming cross-resistant to drugs typically used in humans. For example, tylosin use in animals appears to select for bacteria also cross-resistant to other macrolides, including erythromycin, commonly used in humans. Concentrations of the drug-resistant bacterial strains generated by CAFOs become increased in water and soil surrounding these farms. If not directly pathogenic in humans, these resistant bacteria may serve as a reservoir of mobile genetic elements that can then pass resistance genes to human pathogens. Fortunately, the cooking process typically inactivates any antimicrobials remaining in meat, so humans typically are not directly ingesting these drugs. Nevertheless, many people are calling for more judicious use of these drugs, perhaps charging farmers user fees to reduce indiscriminate use. In fact, in 2012, the FDA published guidelines for farmers who voluntarily phase out the use of antimicrobial drugs except under veterinary supervision and when necessary to ensure animal health. Although following the guidelines is voluntary at this time, the FDA does recommend what it calls “judicious” use of antimicrobial drugs in food-producing animals in an effort to decrease antimicrobial resistance. Clinical Focus Part 3 Unfortunately, Marisa’s urinary tract infection did not resolve with ciprofloxacin treatment. Laboratory testing showed that her infection was caused by a strain of Klebsiella pneumoniae with significant antimicrobial resistance. The resistance profile of this K. pneumoniae included resistance to the carbapenem class of antibacterials, a group of β-lactams that is typically reserved for the treatment of highly resistant bacteria. K. pneumoniae is an opportunistic, capsulated, gram-negative rod that may be a member of the normal microbiota of the intestinal tract, but may also cause a number of diseases, including pneumonia and UTIs. Specific laboratory tests looking for carbapenemase production were performed on Marisa’s samples and came back positive. Based upon this result, in combination with her health history, production of a carbapenemase known as the New Delhi Metallo-β-lactamase (NDM) was suspected. Although the origin of the NDM carbapenemase is not completely known, many patients infected with NDM-containing strains have travel histories involving hospitalizations in India or surrounding countries. How would doctors determine which types of antimicrobial drugs should be administered? Jump to the next Clinical Focus box. Go back to the previous Clinical Focus box. 14.6 Testing the Effectiveness of Antimicrobials Learning Objectives Describe how the Kirby-Bauer disk diffusion test determines the susceptibility of a microbe to an antibacterial drug. Explain the significance of the minimal inhibitory concentration and the minimal bactericidal concentration relative to the effectiveness of an antimicrobial drug. Testing the effectiveness of antimicrobial drugs against specific organisms is important in identifying their spectrum of activity and the therapeutic dosage . This type of test, generally described as antimicrobial susceptibility testing (AST) , is commonly performed in a clinical laboratory. In this section, we will discuss common methods of testing the effectiveness of antimicrobials. The Kirby-Bauer Disk Diffusion Test The Kirby-Bauer disk diffusion test has long been used as a starting point for determining the susceptibility of specific microbes to various antimicrobial drugs. The Kirby-Bauer assay starts with a Mueller-Hinton agar plate on which a confluent lawn is inoculated with a patient’s isolated bacterial pathogen. Filter paper disks impregnated with known amounts of antibacterial drugs to be tested are then placed on the agar plate. As the bacterial inoculum grows, antibiotic diffuses from the circular disk into the agar and interacts with the growing bacteria. Antibacterial activity is observed as a clear circular zone of inhibition around the drug-impregnated disk, similar to the disk-diffusion assay depicted in Figure 13.31 . The diameter of the zone of inhibition, measured in millimeters and compared to a standardized chart, determines the susceptibility or resistance of the bacterial pathogen to the drug. There are multiple factors that determine the size of a zone of inhibition in this assay, including drug solubility, rate of drug diffusion through agar, the thickness of the agar medium, and the drug concentration impregnated into the disk. Due to a lack of standardization of these factors, interpretation of the Kirby-Bauer disk diffusion assay provides only limited information on susceptibility and resistance to the drugs tested. The assay cannot distinguish between bacteriostatic and bactericidal activities, and differences in zone sizes cannot be used to compare drug potencies or efficacies. Comparison of zone sizes to a standardized chart will only provide information on the antibacterials to which a bacterial pathogen is susceptible or resistant. Check Your Understanding How does one use the information from a Kirby-Bauer assay to predict the therapeutic effectiveness of an antimicrobial drug in a patient? Micro Connections Antibiograms: Taking Some of the Guesswork Out of Prescriptions Unfortunately, infectious diseases don’t take a time-out for lab work. As a result, physicians rarely have the luxury of conducting susceptibility testing before they write a prescription. Instead, they rely primarily on the empirical evidence (i.e., the signs and symptoms of disease) and their professional experience to make an educated guess as to the diagnosis, causative agent(s), and drug most likely to be effective. This approach allows treatment to begin sooner so the patient does not have to wait for lab test results. In many cases, the prescription is effective; however, in an age of increased antimicrobial resistance, it is becoming increasingly more difficult to select the most appropriate empiric therapy. Selecting an inappropriate empiric therapy not only puts the patient at risk but may promote greater resistance to the drug prescribed. Recently, studies have shown that antibiograms are useful tools in the decision-making process of selecting appropriate empiric therapy. An antibiogram is a compilation of local antibiotic susceptibility data broken down by bacterial pathogen. In a November 2014 study published in the journal Infection Control and Hospital Epidemiology , researchers determined that 85% of the prescriptions ordered in skilled nursing facilities were decided upon empirically, but only 35% of those prescriptions were deemed appropriate when compared with the eventual pathogen identification and susceptibility profile obtained from the clinical laboratory. However, in one nursing facility where use of antibiograms was implemented to direct selection of empiric therapy, appropriateness of empiric therapy increased from 32% before antibiogram implementation to 45% after implementation of antibiograms. 24 Although these data are preliminary, they do suggest that health-care facilities can reduce the number of inappropriate prescriptions by using antibiograms to select empiric therapy, thus benefiting patients and minimizing opportunities for antimicrobial resistance to develop. 24 J.P. Furuno et al. “Using Antibiograms to Improve Antibiotic Prescribing in Skilled Nursing Facilities.” Infection Control and Hospital Epidemiology 35 no. Suppl S3 (2014):S56–61. Link to Learning Visit this website to view an interactive antibiogram provided by Stanford University. Dilution Tests As discussed, the limitations of the Kirby-Bauer disk diffusion test do not allow for a direct comparison of antibacterial potencies to guide selection of the best therapeutic choice. However, antibacterial dilution tests can be used to determine a particular drug’s minimal inhibitory concentration (MIC) , the lowest concentration of drug that inhibits visible bacterial growth, and minimal bactericidal concentration (MBC) , the lowest drug concentration that kills ≥99.9% of the starting inoculum. Determining these concentrations helps identify the correct drug for a particular pathogen. For the macrobroth dilution assay, a dilution series of the drug in broth is made in test tubes and the same number of cells of a test bacterial strain is added to each tube ( Figure 14.19 ). The MIC is determined by examining the tubes to find the lowest drug concentration that inhibits visible growth; this is observed as turbidity (cloudiness) in the broth. Tubes with no visible growth are then inoculated onto agar media without antibiotic to determine the MBC. Generally, serum levels of an antibacterial should be at least three to five times above the MIC for treatment of an infection. The MIC assay can also be performed using 96-well microdilution trays, which allow for the use of small volumes and automated dispensing devices, as well as the testing of multiple antimicrobials and/or microorganisms in one tray ( Figure 14.20 ). MICs are interpreted as the lowest concentration that inhibits visible growth, the same as for the macrobroth dilution in test tubes. Growth may also be interpreted visually or by using a spectrophotometer or similar device to detect turbidity or a color change if an appropriate biochemical substrate that changes color in the presence of bacterial growth is also included in each well. The Etest is an alternative method used to determine MIC, and is a combination of the Kirby-Bauer disk diffusion test and dilution methods. Similar to the Kirby-Bauer assay, a confluent lawn of a bacterial isolate is inoculated onto the surface of an agar plate. Rather than using circular disks impregnated with one concentration of drug, however, commercially available plastic strips that contain a gradient of an antibacterial are placed on the surface of the inoculated agar plate ( Figure 14.21 ). As the bacterial inoculum grows, antibiotic diffuses from the plastic strips into the agar and interacts with the bacterial cells. Because the rate of drug diffusion is directly related to concentration, an elliptical zone of inhibition is observed with the Etest drug gradient, rather than a circular zone of inhibition observed with the Kirby-Bauer assay. To interpret the results, the intersection of the elliptical zone with the gradient on the drug-containing strip indicates the MIC. Because multiple strips containing different antimicrobials can be placed on the same plate, the MIC of multiple antimicrobials can be determined concurrently and directly compared. However, unlike the macrobroth and microbroth dilution methods, the MBC cannot be determined with the Etest. Check Your Understanding Compare and contrast MIC and MBC. Clinical Focus Resolution Marisa’s UTI was likely caused by the catheterizations she had in Vietnam. Most bacteria that cause UTIs are members of the normal gut microbiota, but they can cause infections when introduced to the urinary tract, as might have occurred when the catheter was inserted. Alternatively, if the catheter itself was not sterile, bacteria on its surface could have been introduced into Marisa’s body. The antimicrobial therapy Marisa received in Cambodia may also have been a complicating factor because it may have selected for antimicrobial-resistant strains already present in her body. These bacteria would have already contained genes for antimicrobial resistance, either acquired by spontaneous mutation or through horizontal gene transfer, and, therefore, had the best evolutionary advantage for adaptation and growth in the presence of the antimicrobial therapy. As a result, one of these resistant strains may have been subsequently introduced into her urinary tract. Laboratory testing at the CDC confirmed that the strain of Klebsiella pneumoniae from Marisa’s urine sample was positive for the presence of NDM, a very active carbapenemase that is beginning to emerge as a new problem in antimicrobial resistance. While NDM-positive strains are resistant to a wide range of antimicrobials, they have shown susceptibility to tigecycline (structurally related to tetracycline ) and the polymyxins B and E ( colistin ). To prevent her infection from spreading, Marisa was isolated from the other patients in a separate room. All hospital staff interacting with her were advised to follow strict protocols to prevent surface and equipment contamination. This would include especially stringent hand hygiene practices and careful disinfection of all items coming into contact with her. Marisa’s infection finally responded to tigecycline and eventually cleared. She was discharged a few weeks after admission, and a follow-up stool sample showed her stool to be free of NDM-containing K. pneumoniae , meaning that she was no longer harboring the highly resistant bacterium. Go back to the previous Clinical Focus box. 14.7 Current Strategies for Antimicrobial Discovery Learning Objectives Describe the methods and strategies used for discovery of new antimicrobial agents. With the continued evolution and spread of antimicrobial resistance, and now the identification of pan-resistant bacterial pathogens, the search for new antimicrobials is essential for preventing the postantibiotic era. Although development of more effective semisynthetic derivatives is one strategy, resistance to them develops rapidly because bacterial pathogens are already resistant to earlier-generation drugs in the family and can easily mutate and develop resistance to the new semisynthetic drugs. Today, scientists continue to hunt for new antimicrobial compounds and explore new avenues of antimicrobial discovery and synthesis. They check large numbers of soils and microbial products for antimicrobial activity by using high-throughput screening methods , which use automation to test large numbers of samples simultaneously. The recent development of the iChip 25 allows researchers to investigate the antimicrobial-producing capabilities of soil microbes that are difficult to grow by standard cultivation techniques in the laboratory. Rather than grow the microbes in the laboratory, they are grown in situ—right in the soil. Use of the iChip has resulted in the discovery of teixobactin , a novel antimicrobial from Mount Ararat, Turkey. Teixobactin targets two distinct steps in gram-positive cell wall synthesis and for which antimicrobial resistance appears not yet to have evolved. 25 L. Losee et al. “A New Antibiotic Kills Pathogens Without Detectable Resistance.” Nature 517 no. 7535 (2015):455–459. Although soils have been widely examined, other environmental niches have not been tested as fully. Since 70% of the earth is covered with water, marine environments could be mined more fully for the presence of antimicrobial-producing microbes. In addition, researchers are using combinatorial chemistry, a method for making a very large number of related compounds from simple precursors, and testing them for antimicrobial activity. An additional strategy that needs to be explored further is the development of compounds that inhibit resistance mechanisms and restore the activity of older drugs, such as the strategy described earlier for β-lactamase inhibitors like clavulanic acid . Finally, developing inhibitors of virulence factor production and function could be a very important avenue. Although this strategy would not be directly antibacterial, drugs that slow the progression of an infection could provide an advantage for the immune system and could be used successfully in combination with antimicrobial drugs. Check Your Understanding What are new sources and strategies for developing drugs to fight infectious diseases? Eye on Ethics The (Free?) Market for New Antimicrobials There used to be plenty of antimicrobial drugs on the market to treat infectious diseases. However, the spread of antimicrobial resistance has created a need for new antibiotics to replace those that are no longer as effective as they once were. Unfortunately, pharmaceutical companies are not particularly motivated to fill this need. As of 2009, all but five pharmaceutical companies had moved away from antimicrobial drug development. 26 As a result, the number of FDA approvals of new antimicrobials has fallen drastically in recent decades ( Figure 14.22 ). 26 H.W. Boucher et al. “Bad Bugs, No Drugs: No ESKAPE! An Update from the Infectious Diseases Society of America.” Clinical Infectious Diseases 48 no. 1 (2009):1–12. Given that demand usually encourages supply, one might expect pharmaceutical companies to be rushing to get back in the business of developing new antibiotics. But developing new drugs is a lengthy process and requires large investments in research and development. Pharmaceutical companies can typically get a higher return on their investment by developing products for chronic, nonmicrobial diseases like diabetes; such drugs must be taken for life, and therefore generate more long-term revenue than an antibiotic that does its job in a week or two. But what will happen when drugs like vancomycin, a superantimicrobial reserved for use as a last resort, begin to lose their effectiveness against ever more drug-resistant superbugs? Will drug companies wait until all antibiotics have become useless before beginning to look for new ones? Recently, it has been suggested that large pharmaceutical companies should be given financial incentives to pursue such research. In September 2014, the White House released an executive order entitled “Combating Antibiotic Resistant Bacteria,” calling upon various government agencies and the private sector to work together to “accelerate basic and applied research and development for new antimicrobials, other therapeutics, and vaccines.” 27 As a result, as of March 2015, President Obama’s proposed fiscal year 2016 budget doubled the amount of federal funding to $1.2 billion for “combating and preventing antibiotic resistance,” which includes money for antimicrobial research and development. 28 Similar suggestions have also been made on a global scale. In December 2014, a report chaired by former Goldman Sachs economist Jim O’Neill was published in The Review on Antimicrobial Resistance . 29 27 The White House. National Action Plan for Combating Antibiotic-Resistant Bacteria. Washington, DC: The White House, 2015. 28 White House Office of the Press Secretary. “Fact Sheet: Obama Administration Releases National Action Plan to Combat Antibiotic-Resistant Bacteria.” March 27, 2015. https://www.whitehouse.gov/the-press-office/2015/03/27/fact-sheet-obama-administration-releases-national-action-plan-combat-ant 29 Review on Antimicrobial Resistance. http://amr-review.org. Accessed June 1, 2016. These developments reflect the growing belief that for-profit pharmaceutical companies must be subsidized to encourage development of new antimicrobials. But some ask whether pharmaceutical development should be motivated by profit at all. Given that millions of lives may hang in the balance, some might argue that drug companies have an ethical obligation to devote their research and development efforts to high-utility drugs, as opposed to highly profitable ones. Yet this obligation conflicts with the fundamental goals of a for-profit company. Are government subsidies enough to ensure that drug companies make the public interest a priority, or should government agencies assume responsibility for developing critical drugs that may have little or no return on investment? Link to Learning To further examine the scope of the problem, view this video. To learn more about the history of antimicrobial drug discovery, visit Michigan State University’s Antimicrobial Resistance Learning Site.